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  • 2000-2004  (29)
  • 1995-1999  (16.515)
  • 1985-1989  (18.079)
  • Polymer and Materials Science  (31.432)
  • Atomic, Molecular and Optical Physics  (1.949)
  • Genetics  (1.242)
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  • 1
    Digitale Medien
    Digitale Medien
    Oligohydramnion, renal failure and no pulmonary hypoplasia in glomerulocystic kidney disease (2000)
    Springer
    Pediatric nephrology 14 (2000), S. 319-321 
    Details
    ISSN: 1432-198X
    Schlagwort(e): Key words Glomerulocystic kidney disease ; Oligohydramnion ; Renal failure-neonate ; Genetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  Two newborns with glomerulocystic kidney disease manifesting as late onset oligohydramnion and neonatal anuria, yet without severe respiratory distress, are presented. They had a similar perinatal course and associated clinical manifestations. No associated congenital or inherited malformation syndrome could be defined. Both infants’ parents were first degree cousins and belonged to the same small Bedouin tribe, and neither they nor the infants’ siblings had polycystic kidneys or renal insufficiency, pointing to either a possible genetic etiology or a common external toxic exposure.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s004670050767
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  • 2
    Digitale Medien
    Digitale Medien
    Susceptibility to critical illness: reserve, response and therapy (2000)
    Springer
    Intensive care medicine 26 (2000), S. S057 
    Details
    ISSN: 1432-1238
    Schlagwort(e): Key words Critical illness ; Intensive care ; Severity of illness ; Scoring systems ; Genetics ; Susceptibility ; Education
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Risk of critical illness is determined both by genetic and environmental influences, particularly those relating to infectious and cardiovascular diseases. Physiologically-based scoring systems cannot measure prior risk because they do not quantify physiological reserve independently of the acute illness. Genetic profiling could be useful for risk assessment. Early detection of critical illness involves identifying physiological ’triggers' for referral; this requires the education of nursing and medical staff in their significance. Analysis of the relationship between risk factors and interventions may need complex modelling techniques. Therapeutic strategies depend on the nature of the underlying problem: the most useful are likely to be those which enhance tissue oxygen delivery and resistance to infection.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001340051120
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  • 3
    Digitale Medien
    Digitale Medien
    Aetiology of overweight and obesity in children and adolescents (2000)
    Springer
    European journal of pediatrics 159 (2000), S. S35 
    Details
    ISSN: 1432-1076
    Schlagwort(e): Key words Obesity ; Genetics ; Child ; Nutrient balance ; Energy balance ; Environment
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The epidemic diffusion of obesity in industrialised countries has promoted research on the aetiopathogenesis of this disorder. The purpose of this review is to focus mainly on the contribution that European research has made to this field. Available evidence suggests that obesity results from multiple interactions between genes and environment. Parents obesity is the most important risk factor for childhood obesity. Twin, adoption, and family studies indicated that inheritance is able to account for 25% to 40% of inter-individual difference in adiposity. Single gene defects leading to obesity have been discovered in animals and, in some cases, confirmed in humans as congenital leptin deficiency or congenital leptin receptor deficiency. However, in most cases, genes involved in weight gain do not directly cause obesity but they increase the susceptibility to fat gain in subjects exposed to a specific environment. Both genetic and environmental factors promote a positive energy balance which cause obesity. The relative inefficiency of self-adapting energy intake to energy requirements is responsible for fat gain in predisposed individuals. The role of the environment in the development of obesity is suggested by the rapid increase of the prevalence of obesity accompanying the rapid changes in the lifestyle of the population in the second half of this century. Early experiences with food, feeding practices and family food choices affect children's nutritional habits. In particular, the parents are responsible for food availability and accessibility in the home and they affect food preferences of their children. Diet composition, in particular fat intake, influences the development of obesity. The high energy density and palatability of fatty foods as well as their less satiating properties promotes food consumption. TV viewing, an inactivity and food intake promoter, was identified as a relevant risk factor for obesity in children. Sedentarity, i.e. a low physical activity level, is accompanied by a low fat oxidation rate in muscle and a low fat oxidation rate is a risk factor of fat gain or fat re-gain after weight loss. Conclusion Further research is needed to identify new risk factors of childhood obesity, both in the genetic and environmental areas, which may help to develop more effective strategies for the prevention and treatment of obesity.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/PL00014361
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  • 4
    Digitale Medien
    Digitale Medien
    Bridging the gap between molecular genetics and metabolic medicine: access to genetic information (2000)
    Springer
    European journal of pediatrics 159 (2000), S. S183 
    Details
    ISSN: 1432-1076
    Schlagwort(e): Key words Database ; Genetics ; Information services ; Internet ; Mutation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Thanks to the World Wide Web, most results of research in genetics are made available in public databases. At the present time there are resources on genetic diseases, genes and their location, mutations of already cloned genes and on laboratories performing the mutation analysis. The main resources on phenotypes are On-line Mendelian Inheritance in Man (OMIM), Pedbase, GeneClinics, London Dysmorphology Database (LDDB) and Orphanet. The main resources on human genes are, in addition to OMIM, the Genome Database, Genatlas and Genecard. There are also two major sequence databases. All of them can be queried using the OMIM number of the disease. Central databases of mutations, as well as locus specific databases have been created. Their list is maintained at the Human Genome Organisation mutation database initiative website. Several initiative have been taken to integrate all these data and help the clinician to find out quickly what he/she needs. The website of the National Center for Biotechnology Information is the best example of such an effort with sections on diseases, a genome guide, and locus links. Several databases of genetic testing resources have been established. GeneTests is an on-line genetics resource that contains a directory of North American laboratories providing testing for heritable disorders. Orphanet is a similar database on French services which is in the process of becoming a European database. Conclusion Even if clinicians do not have as many services at their disposal as the molecular geneticists, various useful databases already exist and should no longer be ignored in practice.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/PL00014399
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  • 5
    Digitale Medien
    Digitale Medien
    Genetic determinants of hyperhomocysteinaemia: the roles of cystathionine β-synthase and 5,10-methylenetetrahydrofolate reductase (2000)
    Springer
    European journal of pediatrics 159 (2000), S. S208 
    Details
    ISSN: 1432-1076
    Schlagwort(e): Key words Cardiovascular disease ; Cystathionine β-synthase ; Genetics ; Methylenetetrahydrofolate reductase ; Mild hyperhomocysteinaemia
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Over the last decade mild hyperhomocysteinaemia has widely been recognised as a new risk factor for arteriosclerosis and thrombosis. Main regulating enzymes of homocysteine (Hcy) metabolism are cystathionine β-synthase (CBS), methionine synthase and methylenetetrahydrofolate reductase (MTHFR). Early studies on patients with vascular disease described elevated Hcy concentrations after methionine loading and decreased CBS activity, resembling heterozygotes for CBS deficiency. Therefore, heterozygosity for CBS deficiency was proposed as the main cause of mild hyperhomocysteinaemia. However, more recent enzymatic and molecular genetic studies have demonstrated that heterozygosity for CBS deficiency is not or only a very minor cause of mild hyperhomocysteinaemia in vascular disease. We discovered two common genetic causes of mild hyperhomocysteinaemia, the 677C 〉 T and the 1298A 〉 C mutations in the coding region of MTHFR. The 677C 〉 T mutation causes reduced enzyme activity with thermolabile protein properties, elevated Hcy and low-normal or decreased plasma folate levels. The 1298A 〉 C mutation relates also to decreased enzyme activity, but not to thermolabile protein, and Hcy and folate levels are not influenced. However, compound heterozygosity for these two mutations, i.e. individuals with the 677CT/1298AC genotype, have elevated Hcy and decreased plasma folate levels. Gene-enviroment interactions between 677C 〉 T and folate is demonstrated in individuals with the 677TT genotype. Those with low-normal folate have elevated Hcy, whereas those with high-normal folate have normal Hcy concentrations. The elevated Hcy levels due to these mutations can be normalised by administration of folate, but whether folate reduces the risk of cardiovascular disease remains to be established. Conclusion Heterozygosity for cystathionine β-synthase deficiency is a minor cause of hyperhomocysteinaemia. The current data on mutations in the methylenetetrahydrofolate reductase gene do not tell us whether elevated plasma homocysteine plays a causal role in vascular disease. Low cellular vitamin status may be a possible cause and homocysteine may just be a marker for this situation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/PL00014405
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  • 6
    Digitale Medien
    Digitale Medien
    Progress in the clinical and molecular genetics of familial parkinsonism (2000)
    Springer
    Neurogenetics 2 (2000), S. 207-218 
    Details
    ISSN: 1364-6753
    Schlagwort(e): Key words Parkinson's disease ; Familial Parkinson's disease ; Synuclein ; Parkin ; Genetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: ABSTRACT¶Parkinson's disease (PD) is a neurodegenerative disease with clinical features resulting from deficiency of dopamine in the nigrostriatal system. Most PD cases are sporadic and the primary cause of the disease is still unknown. Recently, familial PD and parkinsonism have received much attention because these forms of the disease might provide clues to the genetic risk factors involved in the pathogenesis of idiopathic PD. To date, two causative genes, α-synuclein and the parkin gene, have been identified. α-Synuclein is involved in the pathogenesis of an autosomal dominant form of PD and constitutes a major component of the Lewy body, which is a pathological hallmark of idiopathic PD. In addition, mutations in the parkin gene have been identified as the cause of autosomal recessive juvenile parkinsonism (AR-JP). AR-JP manifests itself as a highly selective degeneration of the substantia nigra and the locus coeruleus, but without Lewy body formation. In addition to these two genes, four chromosomal loci have been linked to other forms of familial PD. Furthermore, there are a number of other pedigrees of familial PD in which linkage to known genetic loci has been excluded. Molecular cloning of these disease genes and elucidation of the function of their gene products will greatly contribute to our understanding of the pathogenesis of idiopathic PD.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s100489900083
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  • 7
    Digitale Medien
    Digitale Medien
    Molecular variation within the dopamine receptor DRD2 gene in migraine (2000)
    Springer
    The journal of headache and pain 1 (2000), S. S147 
    Details
    ISSN: 1129-2377
    Schlagwort(e): Key words Dopamine ; Migraine ; Genetics ; DRD2
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Molecular genetics offers a novel approach to the understanding and management of migraine since the disorder is known to have a strong genetic component. In recent studies, polymorphisms in the genes for dopamine receptors have been evaluated. Both positive and negative association studies have been reported. In particular, these data suggest that activation of the DRD2 receptor plays a modifying role in the pathophysiology of migraine. As a result, existing data provide a molecular rationale for the documented efficacy of dopamine D2 receptor antagonists in the treatment of migraine. Therefore, at the present time, molecular genetic data provide support for the hypothesis that susceptibility to migraine may be modified, in part, by variations in dopamine DRD2 receptor function.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s101940070009
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  • 8
    Digitale Medien
    Digitale Medien
    Genetic factors in migraine and chronic tension-type headache (2000)
    Springer
    The journal of headache and pain 1 (2000), S. S157 
    Details
    ISSN: 1129-2377
    Schlagwort(e): Key words Migraine ; Chronic tension type headache ; Genetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Pathophysiological studies have dominated migraine research for several years. However, these studies are difficult to interpret because it is difficult to decide whether the observed phenomena are primary or secondary to the migraine attack. For that reason it is important that future migraine research focus on studies that concern migrain etiology. Migraine is a paroxysmal disorder. It is most likely and ion-channel disorder like familial hemiplegic migraine. The present paper focuses on genetic factors in migraine and chronic tension-type headache.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s101940070011
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  • 9
    Digitale Medien
    Digitale Medien
    A study of Italian families with cluster headache (2000)
    Springer
    The journal of headache and pain 1 (2000), S. S165 
    Details
    ISSN: 1129-2377
    Schlagwort(e): Key words Cluster headache ; Familial occurrence ; Genetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract A Danish genetic study showed increased risk of cluster headache (CH) among relatives of CH patients. We studied the families of 191 CH patients (118 males, 73 females; mean age 45.9 years) attending the Milan Headache Center. Information on 3589 relatives was collected by direct interview of the probands (n = 118) or by mailed questionnaire (n = 73). The diagnostic criteria of the IHS were used. A positive family history was found in 19% (37 of 191) of the families. A total of 32 first-degree (32 of 1036, 3.1%) and 15 second-degree (15 of 2553, 0.6%) relatives were affected. The relative risk of CH was 26.89 (95% CI, 17.57–36.21) in the first-degree relatives and 4.35 (95% CI, 2.13–5.21) in second-degree relatives. This study shows increased familial risk of cluster headache in an Italian population and confirms that cluster headache is, in some families, and inherited disorder.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s101940070012
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  • 10
    Digitale Medien
    Digitale Medien
    Molecular genetics and migraine (2000)
    Springer
    The journal of headache and pain 1 (2000), S. S135 
    Details
    ISSN: 1129-2377
    Schlagwort(e): Key words Migraine ; Headache ; Genetics ; Serotonin ; Dopamine ; Mitochondria
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Migraine carries a significant hereditary determination. Familial hemiplegic migraine (FHM) has been recently linked to mutations in the CACNA1A gene on chromosome 19. CACNA1A codes for a subunit of a neural calcium channel. Other linkage loci on chromosome 1q21-23 and 1q31 have been reported. Several linkage and association studies have been performed to determine the role of the CACNA1A gene, and of other candidate genes implicated in the metabolism of serotonin and dopamine, in the more common types of migraine. Co-morbidity of migraine with vascular events has been analysed versus genetic prothrombotic factors and mitochondrial DNA, and genes involved in the inflammatory cascade have been explored. Though no definite conclusions have emerged from these studies as yet, molecular genetics of migraine can be expected to unravel the complex aetiologies of these fascinating diseases.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s101940070007
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  • 11
    Digitale Medien
    Digitale Medien
    Dopamine genes and migraine (2000)
    Springer
    The journal of headache and pain 1 (2000), S. S153 
    Details
    ISSN: 1129-2377
    Schlagwort(e): Key words Migraine ; Genetics ; Dopamine ; Hypersensitivity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Migraine is a common chronic disorder with an etiology still mostly unknown. Several neurotransmitters such as dopamine and serotonin are considered to be involved in the pathogenesis of the disease and the study of their systems is crucial in the understanding of migraine. Dopaminergic receptors are variously represented in human CNS and periphery. The hypothesis that a hypersensitivity of the dopaminergic system may have a role in migraine is based on clinical and genetic data. Genetic data are represented by association studies using dopaminergic genes as candidate genes which show that the D2 receptor gene appears to be involved in the pathogenesis of migraine.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s101940070010
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  • 12
    Digitale Medien
    Digitale Medien
    HLA and migraine genes (2000)
    Springer
    The journal of headache and pain 1 (2000), S. S141 
    Details
    ISSN: 1129-2377
    Schlagwort(e): Key words Migraine ; Genetics ; Human leukocyte antigens ; Heredity ; Susceptibility
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Human leukocyte Antigens (HLA) are encoded by genes located on chromosome 6p21. Genes important in migraine are being recognized in two basic ways: association studies and linkage analysis. One of the strongest associations is with the HLA region. Actually, genome scan studies suggest that multiple genes are involved in both migraine without aura (MWoA) and migraine with aura (MWA). However, both MWoA and MWA are disorders in which multiple factors, including environmental and genetic factors, confer disease susceptibility. Linkage analysis is identifying new candidate genes that will help to explain the etiology of migraine. In this review previous studies regarding genetic susceptibility to migraine are analyzed, particularly those related to the HLA region. I discuss evidence that HLA shared-hyplotypes in MWoA-affected pairs in different than that expected, that HLA-DR2 antigen provides additional basis for the proposed genetic heterogeneity between MWoA and MWA, and lastly that TNFB gene studies seem to play an important role in the susceptibility to MWoA. In the past years, major advances hae been made in understanding the genetic foundation of MWoA and MWA. Our reported genome-scan studies support the concept that MWoA/MWA are coinherited with a particular HLA region. However, the examination of candidate genes (Ca2+ channel, vascular, CNS, etc.) in a large migraine population seems to be the correct direction in which we have to move. More MWoA/MWa gene studies are needed to test this developing hypothesis and to further establish the complete genetic scenario of migraine.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s101940070008
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  • 13
    Digitale Medien
    Digitale Medien
    A novel hypersensitive resistance response against potato virus A in cultivar ’Shepody’ (2000)
    Springer
    Theoretical and applied genetics 100 (2000), S. 401-408 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Key words Complementary genes ; Extreme virus resistance ; Genetics ; Necrotic tubers ; Restricted virus distribution ; Solanum tuberosum
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  The potato cultivar ’Shepody’ is susceptible to a number of potato viruses including potato virus Y (PVY, potyvirus) but was found to possess extreme resistance to another potyvirus, potato virus A (PVA). ’Shepody’ plants were resistant to PVA infection in manual and graft inoculations. PVA replication was not detected in any of the inoculated plants by ELISA, an infectivity assay and RT-PCR. However, ’Shepody’ plants grafted with shoots containing PVA developed a novel symptomology which resembled a virus infection in appearance and in rate of translocation to the entire plant. Efforts to transmit the symptom-inducing agent manually failed. Graft-inoculation to potato virus indicator plants and PVA-susceptible potato plants showed that the symptom inducer was PVA at an extremely low concentration, detected using RT-PCR followed by Southern blot assay. Tubers from grafted but resistant ’Shepody’ plants had necrotic surfaces and internal spots. PVA was detected from necrotic areas but not from the non-necrotic ones. However, plants resulting from necrotic tubers were free from aerial leaf symptoms observed in grafted plants and produced non-necrotic normal tubers. A trace-back of the parental lineage of ’Shepody’ indicated that the resistance had been introgressed from the cultivar ’Bake King’. Analysis of progeny of a cross of resistant ’Shepody’ to the susceptible ’Goldrus’ indicated that this resistance is controlled by two independent dominant complementary genes in contrast to monogenic resistance reported for other potato viruses.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001220050053
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  • 14
    Digitale Medien
    Digitale Medien
    Characterisation and analysis of microsatellite loci in a mangrove species, Avicennia marina (Forsk.) Vierh. (Avicenniaceae) (2000)
    Springer
    Theoretical and applied genetics 101 (2000), S. 279-285 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Key words Avicennia marina ; Microsatellite ; Mangrove ; Genetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  An enriched microsatellite library of the mangrove species Avicennia marina was constructed, in which 85.8% of the clones contained microsatellite sequences. Of the microsatellite repeat sequences isolated, 55.0% were di-nucleotides, 34.2% were tri-nucleotides, 50.0% were perfect, 24.2% were imperfect, and 15.0% were compound. Four different di-nucleotide repeats were isolated with repeat lengths ranging from 5 to 33; ten different tri-nucleotide repeats were isolated with repeat lengths ranging from 3 to 25. The most common di-nucleotide was the AC/TG repeat; the most common tri-nucleotide was the CCG/GGC repeat. Sixteen microsatellite sequences were selected for primer design, and 6 primers were selected to investigate the polymorphism detected among 15 individuals of A. marina from three natural populations in Australia. A total of 40 alleles were detected at 6 microsatellite loci. The number of alleles per microsatellite locus ranged from 5 to 13. On average, 7 alleles were detected per locus. All microsatellite loci showed high levels of gene diversity (heterozygosity), with values ranging from 0.53 to 0.88; the mean value of gene diversity was 0.70. Microsatellite loci were also tested for conservation across Avicennia species. There was a decline in amplification success with increasing divergence between Avicennia species. The results indicate that microsatellites are abundant in the Avicennia genome and can be valuable genetic markers for assessing the effects of deforestation and forest fragmentation in mangrove communities, which is an important issue for mangrove conservation and afforestation schemes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001220051480
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  • 15
    Digitale Medien
    Digitale Medien
    Re-examination of (in)compatibility genotypes of two John Innes self-compatible sweet cherry selections (2000)
    Springer
    Theoretical and applied genetics 101 (2000), S. 234-240 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Key words Cherry ; Genetics ; Compatibility ; Incompatibility ; Isoelectric focusing ; Prunus avium ; Ribonuclease
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  The (in)compatibility genotypes of two self-compatible sweet cherry selections, JI 2420 and JI 2434, originating from the John Innes Institute were re-examined. The selections and seedlings derived from them were analysed for stylar ribonucleases, which are known to correlate with S alleles, and the outcome of test crosses was recorded. JI 2420, which had been reported previously as S 3 S 4 ", where " indicates loss of pollen activity, was deduced to have the genotype S 4 S 4 ’. For JI 2434, which had been reported previously as S 3 S 4 0 , S 3 S 3 0 or S 3 S 3 ", where 0 indicates loss of pollen and stylar activity, two different clones were identified. One, at East Malling, was deduced to be S 3 "S 4 ; the other, at Ahrensburg, appeared to be S 3 S 3 " or S 3 S 3 0 .
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001220051474
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  • 16
    Digitale Medien
    Digitale Medien
    Association of TNFA gene polymorphism at position –308 with susceptibility to irritant contact dermatitis (2000)
    Springer
    Immunogenetics 51 (2000), S. 201-205 
    Details
    ISSN: 1432-1211
    Schlagwort(e): Key words Skin ; Genetics ; TNFA ; ¶Inflammation ; PCR-RFLP
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract  Mechanisms underlying susceptibility to skin irritants are not clearly understood. Cytokines play a key role in inflammation, and functional polymorphisms in cytokine genes may affect responses to irritants. We investigated the relationship between polymorphism in the tumor necrosis factor (TNF) α-chain gene and responses to irritants. Volunteers (n=221) tested with sodium dodecyl sulfate (SDS) and benzalkonium chloride (BKC) were divided into responders and nonresponders and high and low irritant-threshold groups. DNA was assayed for the TNF-308 polymorphism by a polymerase chain reaction-restriction fragment length polymorphism method. There was a significant increase in the A allele (P=0.030) and AA genotype (P=0.023) in both the SDS low irritant-threshold group and in SDS responders (A allele P=0.022, AA genotype P=0.048). In the BKC low irritant-threshold group, we found a significant increase in the A allele (P=0.002) and AA genotype (P=0.016). Individuals with a low threshold to both irritants demonstrated a significant increase (P=0.002) in the A allele. This is the first description of a nonatopic genetic marker for irritant susceptibility in normal individuals. Genotyping for theTNF-308 polymorphism may thus contribute to screening of individuals deemed at risk of developing irritant contact dermatitis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002510050032
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  • 17
    Digitale Medien
    Digitale Medien
    Progressive supranuclear palsy: earlier age of onset in patients with the τ protein A0/A0 genotype (2000)
    Springer
    Journal of neurology 247 (2000), S. 206-208 
    Details
    ISSN: 1432-1459
    Schlagwort(e): Key words Progressive ¶supranuclear palsy ; Genetics ; Clinical characteristics ; Parkinsonism
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Genetic studies have detected an association between the presence of the τ gene A0 allele and patients with progressive supranuclear palsy (PSP). This study examined whether patients with this polymorphism exhibit distinct demographic or clinical characteristics. We studied 26 patients who fulfilled clinical criteria for the diagnosis of PSP, 20 who had the A0/A0 genotype and 6 who had other genotypes. A questionnaire on demographic data, past medical history, familial history, and initial symptoms was completed as part of the consultation. A complete neurological examination was performed and PSP symptoms were quantified following Golbe’s PSP disability scale. We found a significant difference in the age at onset of PSP symptoms, which was 65.9 ± 5.3 years in the A0/A0 group and 71.2 ± 5.6 in the non-A0/A0 group (P = 0.016). There were no significant differences in the years from disease onset between the two groups. Symptom severity did not differ significantly in patients with the different A0/A0 genotypes. The detection of significantly lower age at onset with the A0/A0 alleles is consistent with the known association of this genotype as a risk factor for PSP. No significant differences were detected in symptom severity between the two groups of patients.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s004150050564
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  • 18
    Digitale Medien
    Digitale Medien
    Genotyping of presenilin-1 polymorphism in amyotrophic lateral sclerosis (2000)
    Springer
    Journal of neurology 247 (2000), S. 940-942 
    Details
    ISSN: 1432-1459
    Schlagwort(e): Key words Amyotrophic lateral sclerosis ; Genetics ; Presenilin-1 intron 8 polymorphism ; Apoptosis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The mechanisms underlying motor neuron degeneration in amyotrophic lateral sclerosis are not fully understood. Recent studies suggest that apoptosis is involved in the abnormal neural death that occurs in this devastating disease. Presenilin-1, a transmembrane protein, seems to be implicated in apoptosis. To determine whether presenilin-1 intron 8 polymorphism has an influence in the course of amyotrophic lateral sclerosis, we examined this polymorphism genotypes in a large group of patients (n=72) with amyotrophic lateral sclerosis and in a random sample of 213 healthy individuals. The results showed a significant difference in genotype (P 〈 0.04) and allele (P 〈 0.03) distribution between patients and controls. These results suggest a possible intervention of presenilin-1 in the pathogenesis of amyotrophic lateral sclerosis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s004150070050
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  • 19
    Digitale Medien
    Digitale Medien
    The monoamine oxidase B gene GT repeat polymorphism and Parkinson’s disease in a Chinese population (2000)
    Springer
    Journal of neurology 247 (2000), S. 52-55 
    Details
    ISSN: 1432-1459
    Schlagwort(e): Key words Parkinson’s disease ; Monoamine oxidase B ; Genetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Monoamine oxidase B (MAOB) metabolises dopamine and activates neurotoxins known to induce parkinsonism in humans and primates. Therefore the MAOB gene (MAOB; Xp15.21–4) is a candidate gene for Parkinson’s disease (PD). Longer length dinucleotide repeat sequences in a highly polymorphic GT repeat region of intron 2 of this gene showed an association with PD in an Australian cohort. We repeated this allele-association study in a population of 176 Chinese PD patients ¶(90 men, 86 women) and 203 age-matched controls (99 men, 104 women). Genomic DNA was extracted from venous blood and the polymerase chain reaction was used to amplify the appropriate regions of the MAOB gene. The length of each (GT) repeat sequence was determined by 5% polyacrylamide denaturing gel electrophoresis. There was no significant difference in allele frequencies of the (GT) repeat allelic variation between patients and controls (χ2 = 2.48; df = 5, P 〈 0.75). Therefore the longer length GT repeat alleles are not associated with PD in this Chinese population. Possible reasons for the discrepancy between Chinese and Australian populations include a different interaction between this genetic factor and environmental factors in the two populations and the possibility that the long length GT repeat alleles may represent a marker mutation, genetically linked to another susceptibility allele in whites but not in Chinese. Methodological differences in the ascertainment of cases and controls in this cohort could also explain the observed differences. Further study is required to determine whether the longer length GT repeat alleles are true susceptibility alleles in PD.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s004150050010
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  • 20
    Digitale Medien
    Digitale Medien
    ICAM-1 gene is not associated with multiple sclerosis in sardinian patients (2000)
    Springer
    Journal of neurology 247 (2000), S. 677-680 
    Details
    ISSN: 1432-1459
    Schlagwort(e): Key words Multiple sclerosis ; Genetics ; ICAM-1 gene
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract An increased amount of the intercellular adhesion molecule (ICAM) 1 molecule has been found in the blood of actively relapsing multiple sclerosis (MS) patients, but is unclear whether this enhanced expression is partially causative of the MS process, or whether it is merely an epiphenomenon of the inflammatory-immunological reaction. Using the transmission disequilibrium test (TDT), we studied exon 4 and exon 6 polymorphism of the ICAM-1 gene from 157 families with both parents, one affected and one healthy sib coming from Sardinia, an Italian island having a high incidence and prevalence of MS. TDT did not show variation in the expected 50:50 frequency in transmission in either healthy or affected sibs, using phenotypic or genotypic analysis. Moreover, independence from the predisposing HLA-DRB1-DQA1-DQB1 haplotype was confirmed by TDT analysis performed on the patients stratified according to the presence or absence of the HLA-DRB1, DQA1, DQB1 Sardinian predisposing haplotypes. Our data suggest that the increased expression of the ICAM-1 molecule observed in both blood and periplaque microvessels may be considered a consequence of the inflammatory process rather than the result of a genetic variation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s004150070109
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  • 21
    Digitale Medien
    Digitale Medien
    Vascular risk factors in dementia (2000)
    Springer
    Journal of neurology 247 (2000), S. 81-87 
    Details
    ISSN: 1432-1459
    Schlagwort(e): Key words Dementia ; Vascular ¶dementia ; Alzheimer’s disease ; Risk factors, stroke ; Genetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract This review describes differing profiles of vascular risk factors in different types of dementia. Although vascular risk factors are related to various types of strokes, their independent effect on the occurrence of poststroke dementia appears to be small. Various risk factors have been identified for microangiopathy-related cerebral abnormalities, such as white matter changes and lacunae, which are the core lesions for the development of a vascular dementia syndrome without stroke symptoms. Most consistently, arterial hypertension and diabetes mellitus have been found to be associated with such brain abnormalities. Diastolic blood pressure seems to be of particular importance as recent investigations demonstrate that this factor is related to the course of multiple lacunar strokes and the progression of white matter disease. Epidemiological studies report that various vascular risk factors including arterial hypertension, diabetes mellitus, and atrial fibrillation may also be associated with Alzheimer’s disease. There is also evidence of a direct relationship between Alzheimer’s disease and general atherosclerosis. Further investigations are needed to determine whether these associations are due to the weakness of diagnostic criteria, or whether vascular risk factors indeed modulate the clinical expression of primary degenerative dementia. Common susceptibility genes leading to shared risk factors may be one of the reasons for a higher coincidence of Alzheimer’s disease and vascular dementia than can be expected by chance. A modulatory effect of vascular risk factors in the development of primary degenerative dementia may extend treatment options.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s004150050021
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  • 22
    Digitale Medien
    Digitale Medien
    Incidence of CSF abnormalities in siblings of multiple sclerosis patients and unrelated controls (2000)
    Springer
    Journal of neurology 247 (2000), S. 616-622 
    Details
    ISSN: 1432-1459
    Schlagwort(e): Key words Multiple sclerosis ; Siblings ; Genetics ; Oligoclonal bands ; Measles
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We found that 19% (9/47) of healthy siblings of patients with clinically definite multiple sclerosis had an intrathecal immunological reaction with two or more 2 CSF-enriched oligoclonal bands (OCBs), in contrast to (4%) (2/50) unrelated healthy controls. Furthermore, in this group of nine healthy sibs the measles CSF IgG antibody titers were higher than that of the other sibs and that of controls. There were also differences in the serum titers for measles IgG antibody, which were higher in the group of all healthy sibs than in healthy volunteers, and (as with CSF titers) higher in the subgroup of healthy sibs with two or more 2 CSF-enriched OCBs than the other sibs. Thus a significant proportion of healthy siblings to MS patients have a partially hyperimmune condition similar to that occurring in MS, which in 19% manifested itself as an OCB reaction, in 9% as increased CSF measles IgG antibody titers, and in 21% as increased serum measles IgG antibody titers, these phenomena tending to occur in the same individuals. This condition is characterized by CSF-enriched OCBs with undefined specificity, although some increased antiviral reactivity is found both in the serum and CSF. While it needs further characterization, a genetic trait interacting with common infections is suggested. The recurrence risk of this condition is approximately five times higher than the 3–4% recurrence risk for manifest MS reported for sibs.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s004150070130
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  • 23
    Digitale Medien
    Digitale Medien
    Dopamine D4 receptor gene polymorphism and personality traits in healthy volunteers (2000)
    Springer
    European archives of psychiatry and clinical neuroscience 250 (2000), S. 203-206 
    Details
    ISSN: 1433-8491
    Schlagwort(e): Key words Dopamine receptor D4 ; Genetics ; Personality inventory ; Polymorphism ; Excitement-Seeking
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract An association between long alleles of a variable number tandem repeat (VNTR) polymorphism in the dopamine receptor D4 gene and the extraversion related personality traits Excitement and Novelty Seeking has been reported in healthy subjects. In an attempt to replicate the previous findings, 256 healthy Caucasian volunteers were analysed for a potential relationship between the dopamine receptor D4 exon III VNTR polymorphism and Extraversion as assessed by the Revised Neo Personality Inventory (NEO PI-R). The present study did not yield evidence for an association between Extraversion and the dopamine receptor D4 polymorphism.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s004060070025
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  • 24
    Digitale Medien
    Digitale Medien
    Dopamine D3 receptor variant and tardive dyskinesia (2000)
    Springer
    European archives of psychiatry and clinical neuroscience 250 (2000), S. 31-35 
    Details
    ISSN: 1433-8491
    Schlagwort(e): Key words Pharmacogenetics ; Genetics ; Risk factor ; Choreoathetotic movements
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract In the search for genetic factors contributing to tardive dyskinesia, dopamine receptor genes are considered major candidates. The dopamine D3 receptor is of primary interest as dopamine D3 receptor knock-out mice show locomotor hyperactivation resembling extrapyramidal side-effects of neuroleptic treatment. Furthermore, Steen and colleagues (1997) recently reported an association between tardive dyskinesia and a dopamine D3 receptor gene variant. In the present study we tried to replicate this finding. We investigated 157 patients with schizophrenia or schizoaffective disorder receiving long-term neuroleptic medication who never or persistently displayed tardive dyskinesia. As advanced age is a main risk factor for tardive dyskinesia, we also compared older patients with a long duration of schizophrenia not displaying tardive dyskinesia to younger patients with a shorter duration of the illness displaying tardive dyskinesia. However, we found no evidence that the dopamine D3 receptor gene is likely to confer susceptibility to the development of tardive dyskinesia.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/PL00007536
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  • 25
    Digitale Medien
    Digitale Medien
    Cavernous angiomas of the nervous system in Italy: clinical and genetic study (2000)
    Springer
    Neurological sciences 21 (2000), S. 129-134 
    Details
    ISSN: 1590-3478
    Schlagwort(e): Key words Nervous system ; Cavernous angiomas ; Genetics ; Onset symptoms
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We performed a clinical and genetic study of patients affected by cavernous angiomas (CA) of the nervous system. We examined initial signs and symptoms in sporadic and familial cases. We obtained clinical, neuroimaging and genetic data on 15 Italian patients with CA of the nervous system with positive, doubtful or apparently negative family history. Genetic markers surrounding three different gene regions (7q, 3q and 7p) were analysed. In one small family, genetic linkage was consistent with all chromosome loci. In another family with the unusual association of cerebral and spinal CA, linkage with chromosome 7q and, likely, 7p was excluded, while linkage with locus 3q was possible. Our results indicate that Italian families with CA may show genetic heterogeneity. Non-specific and subtle onset symptoms hide the presence of CA within families. Patients with multiple CA may have silent cerebral lesions confirming the low penetrance of clinical signs in spite of radiological ones.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s100720070087
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  • 26
    Digitale Medien
    Digitale Medien
    A pathophysiological study of neuronal ceroid lipofuscinoses in 17 patients: critical review and methodological proposal (2000)
    Springer
    Neurological sciences 21 (2000), S. S89 
    Details
    ISSN: 1590-3478
    Schlagwort(e): Key words Evoked potentials ; Ceroid lipofuscinoses ; Mutation ; Classification ; Genetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The importance of visual evoked potential (VEPs) and electroencephalography for diagnosing and distinghishing the infantile (INCL), late-infantile (LINCL) and juvenile (JNCL) forms of neuronal ceroid lipofuscinoses (NCL) is well established. Variant forms with protracted clinical courses and atypical symptoms have been described recently, whose neurophysiological characteristics sometimes overlap those of LINCL and JNCL. It is unclear whether these variant forms are due to phenotypic variability of known genetic defects, or represent new mutations. Twenty-eight NCL patients have been diagnosed at our institute; a proportion of them were investigated genetically. In 17 we performed neurophysiological investigations including VEPs, brainstem auditory (BAEP) and upper limb somatosensory (SEP) evoked potentials. We found typical and diagnostic electrophysiological involvement of the visual system in 8 patients with classic forms of NCL. Furthermore, the distinctive features of the multimodal evoked potentials in most of the six patients with variant NCL suggest that these are distinct genetic entities.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s100720070046
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  • 27
    Digitale Medien
    Digitale Medien
    Alcohol-sensitive hereditary essential myoclonus with dystonia: a study of 6 Brazilian patients (2000)
    Springer
    Neurological sciences 21 (2000), S. 373-377 
    Details
    ISSN: 1590-3478
    Schlagwort(e): Key words Myoclonus-dystonia ; Essential myoclonus ; Dystonia ; Alcohol ; Genetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We present the clinical profile of a group of patients with myoclonus and dystonia sensitive to alcohol and address these cases in the context of essential myoclonus. Six patients from 4 families were selected: 4 men and 2 women with myoclonus affecting predominantly the arms. Active movements of these segments elicited the dystonic and myoclonic movements. A marked improvement with alcohol intake was seen. Laboratory findings including EEG, SSEP, and cranial CT and MRI were normal. Surface EMG recording showed bursts with duration of 30–112 ms in 3 patients. One patient showed a triphasic recording pattern (agonist-antagonist-agonist) of ballistic type. Our findings suggest that the myoclonus-dystonia disorder is present in Brazilian patients.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s100720070053
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  • 28
    Digitale Medien
    Digitale Medien
    Central nervous system hemangioblastomas, endolymphatic sac tumors, and von Hippel-Lindau disease (2000)
    Springer
    Neurosurgical review 23 (2000), S. 1-22 
    Details
    ISSN: 1437-2320
    Schlagwort(e): Key words Von Hippel-Lindau disease ; Hemangioblastoma ; Endolymphatic sac tumor ; Angiogenesis ; Genetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  Von Hippel-Lindau disease (VHL) is a hereditary cancer syndrome caused by germline mutations of the VHL tumor suppressor gene. Major progress has been made in the last decade in both clinical and fundamental aspects of VHL. The VHL gene product, pVHL, has major and multiple functions: pVHL regulates not only first angiogenesis but also extracellular matrix formation and the cell cycle. A molecular diagnosis of VHL is now available, leading to a transformation in clinical management of patients and their families. Diagnosis of VHL has to be suspected in patients with a VHL-related tumor without familial history and especially in case of hemangioblastoma or endolymphatic sac tumors. Such patients should be systematically investigated for clinical and molecular evidence of VHL disease. Treatment of symptomatic hemangioblastomas remains mainly neurosurgical, often in emergency, but stereotactic radiosurgery is emerging as an alternative therapeutic procedure. In the future, antiangiogenic drugs could represent a potential medical treatment of CNS hemangioblastomas in view of their highly vascular structure. Lastly, visceral manifestations of VHL disease are also of critical importance and require early detection for effective treatment.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s101430050024
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  • 29
    Digitale Medien
    Digitale Medien
    Perspectives in pediatric neurosurgery (2000)
    Springer
    Child's nervous system 16 (2000), S. 809-820 
    Details
    ISSN: 1433-0350
    Schlagwort(e): Keywords Pediatric neurosurgery ; Molecular biology ; Genetics ; Novel therapeutics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  The new millennium beckons for novel advances in the diagnosis and treatment of pediatric neurosurgical conditions. Almost every aspect of pediatric neurosurgery has changed over the last decade. Undoubtedly with the application of knowledge in molecular biology to human disease many aspects of neurosurgery, especially neuro-oncology and the field of neuro-developmental anomalies, will change appreciably over the next decade. Overall, the trend in surgery in general and neurosurgery in particular is toward less invasive procedures and possibly non-surgical interventions. This review will briefly cover many of the important areas of pediatric neurosurgery. We will describe the state-of-the-art of our subspecialty and discuss possible future directions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s003810000345
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  • 30
    Digitale Medien
    Digitale Medien
    Mitochondrial DNA mutation at np 3243 in a family with maternally inherited diabetes mellitus (1999)
    Springer
    Acta diabetologica 36 (1999), S. 163-167 
    Details
    ISSN: 1432-5233
    Schlagwort(e): Key words Mitochondrial DNA ; Genetics ; Maternally inherited diabetes mellitus ; Deafness ; np 3243 mutation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Mitochondrial DNA (mtDNA) gene defects may play a role in the development of maternally inherited diabetes mellitus and deafness (MIDD). A family from Southern Italy who showed maternal transmission of type 2 diabetes mellitus with three individuals affected is described. A 10.4 kb deletion and mutations at nucleotide positions (np) 3243, 7445 and 11778 in the mtDNA of six relatives were sought. The mitochondrial np 3243 mutation of the tRNA Leu (UUR) gene was identified in a boy affected by optic atrophy and mental retardation, as well as in his diabetic mother. No other mutations or deletions were found. Our study points out the variable phenotypic expression of the np 3243 mtDNA mutation. This may suggest the presence of other mitochondrial or nuclear mutations required to modulate the phenotype. A clinical and metabolic follow-up of all family members was necessary to understand the role of the np 3243 mutation, especially in one child affected by optic atrophy and mental retardation. Further studies will be aimed at investigating the prevalence of mutations and deletions of mtDNA in type 2 diabetes mellitus.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s005920050161
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  • 31
    Digitale Medien
    Digitale Medien
    AC/GT and AG/CT microsatellite repeats in peach [Prunus persica (L) Batsch]: isolation, characterisation and cross-species amplification in Prunus (1999)
    Springer
    Theoretical and applied genetics 99 (1999), S. 65-72 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Key words Simple sequence repeat (SSR) ; Microsatellites ; Molecular markers ; Genetics ; Fingerprinting
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  We report the sequences of 17 primer pairs of microsatellite loci, which we have cloned and sequenced from two genomic libraries of peach [Prunus persica (L) Batsch] ‘Redhaven’, enriched for AC/GT and AG/CT repeats respectively. For ten of these microsatellite loci we were able to demonstrate Mendelian inheritance in a segregating back-cross population; the remainder did not segregate. The polymorphism of the microsatellites was evaluated in a panel of ten peach genotypes, including true-to-type peaches, nectarines and one canning-peach. Fifteen microsatellites (88%) were polymorphic showing 2–4 alleles each. The mean heterozygosity, averaged over all loci, was 0.32 and significantly higher than that reported in the literature for isozymes and molecular markers, such as RFLPs and RAPDs. We have also assayed the cross-species transportability and found that ten microsatellite (59%) gave apparently correct amplification in all Prunus species surveyed, namely P. domestica (European plum), P. salicina (Japanese plum), P. armeniaca (apricot), P. dulcis (almond), P. persica var. vulgaris (peach), P. persica var. laevis (nectarine), P. avium (sweet cherry) and P. cerasus (sour cherry), with three of them also being amplified in Malus (apple). The remaining microsatellites gave less-extensive amplification. Because of their appreciable polymorphism and wide cross-species transportability, most of these new markers can be integrated into the linkage maps which are currently being constructed in peach, as well as in other stone fruit crops, such as almond, apricot, cherry and plum.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001220051209
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  • 32
    Digitale Medien
    Digitale Medien
    Pathologie der Rhabdo- myosarkome des Kindes- und Adoleszentenalters Ein Bericht des Kindertumorregisters bei der Gesellschaft für Pädiatrische Onkologie und Hämatologie (GPOH) (1999)
    Springer
    Der Pathologe 20 (1999), S. 87-97 
    Details
    ISSN: 1432-1963
    Schlagwort(e): Schlüsselwörter Rhadomyosarkom ; Klassifizierung ; Immunhistochemie ; Genetik ; Prognose ; Key words Rhabdomyosarcoma ; Classification ; Immunohistochemistry ; Genetics ; Prognosis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Summary Rhabdomyosarcoma (RMS) is the most important and a very heterogeneous group of malignant soft tissue tumors of childhood and adolescence.The two major subtypes (embryonal and alveolar) share a common myogenic differentiation, but seem to be histogenetically not related. The so-called ’International Classification of Rhabdomyosarcoma’ includes, besides the two major subtypes, the botryoid and leiomyomatous subtypes of embryonal RMS which are associated with a better prognosis and are treated less aggressively according to current protocols. In addition, the solid variant of alveolar RMS is included in the alveolar group of RMS. The identification of the various subtypes is necessary and important because the treatment with the current protocols is also related to histology. Using conventional stains and immunohistochemistry, these subtypes are distinguishable. Genetic analysis can be helpful in the demonstration of t(2;13) or t(1;13) translocations in alveolar RMS. The identification of alveolar RMS with t(1;13) translocation might become important in the future, because this type of translocation seems to be related to a better prognosis as compared to tumors with a t(2;13) translocation.
    Notizen: Zusammenfassung Rhabdomyosarkome stellen eine heterogene Gruppe von ganz verschiedenartigen, histogenetisch wohl nicht zusammengehörenden Tumoren dar. Nach der heute verwendeten „Internationalen Klassifikation” der Rhabdomyosarkome werden neben der Unterteilung in embryonalen und alveoläre Rhabdomyossarkome auch Subtypen des embryonalen RMS identifiziert (botryoider und leiomyomatöser Subtyp), die durch eine günstigere Prognose und durch die Notwendigkeit einer weniger aggressive Therapie gekennzeichnet sind. Durch Einsatz von verschiedenen histologischen und immunhistochemischen Färbungen ist die Identifizierung der verschiedenen Typen der RMS heute möglich und auch zwingend notwendig, da die einzelnen Entitäten nach ganz unterschiedlichen Therapieprotokollen behandelt werden. Der Nachweis typischer molekulargenetischer Veränderungen kann in der Unterscheidung insbesondere von embryonalen und alveolären RMS hilfreich sein. In der Regel ist die Abgrenzung zwischen diesen beiden Entitäten auch an konventionell gefärbten Schnittpräparaten möglich. Die Identifizierung von alveolären RMS mit einer t(1;13)-Translokation könnte in Zukunft eine große Bedeutung haben, da diese genetische Veränderung möglicherweise mit einer günstigeren Prognose assoziert sein könnte als die t(2;13)-Translokation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002920050326
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  • 33
    Digitale Medien
    Digitale Medien
    Etiology of the inflammatory bowel diseases (1999)
    Springer
    International journal of colorectal disease 14 (1999), S. 2-9 
    Details
    ISSN: 1432-1262
    Schlagwort(e): Key words Inflammatory bowel disease ; Crohn's disease ; Ulcerative colitis ; Epidemiology ; Genetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Inflammatory bowel diseases (IBD) are complex disorders. While the exact etiology of these diseases remains unknown, recent progress in the epidemiology and genetics of IBD has clearly demonstrated both environmental and genetic factors to play a role in the development of the disease, and it is expected that some risk factors are common for both Crohn's disease (CD) and ulcerative colitis (UC). The environmental factor(s) are associated with the Western way of life in the second half of the twentieth century. Cigarette smoking is presently the best known environmental factor. However, the effect of tobacco is opposite in CD and UC. A familial history of IBD is the most important risk factor for developing the disease, suggesting a genetic predisposition to IBD. This hypothesis has recently been confirmed by the localization of at least two susceptibility loci on chromosomes 12 and 16. These genes seem to play a role in both CD and UC. They must now to be identified.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s003840050175
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  • 34
    Digitale Medien
    Digitale Medien
    Genetik schizophrener Störungen Neuere Konzepte und Befunde (1999)
    Springer
    Der Nervenarzt 70 (1999), S. 955-969 
    Details
    ISSN: 1433-0407
    Schlagwort(e): Schlüsselwörter Schizophrenie ; Genetik ; Schizophrenes Spektrum ; Kopplungsuntersuchungen ; Assoziationsuntersuchungen ; Key words Schizophrenia ; Genetics ; Schizophrenia spectrum ; Linkage studies ; Association studies
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Summary Schizophrenia is a genetic complex disease as it does not follow monogenic transmission while non-familial environmental factors have a strong additional impact. A heterogenous, continuous phenotype is transmitted in families which can now be more precisely characterized. Genes coding for proteins with presumed pathophysiological relevance are apparently not playing a major causal role. However, in the last three years several (currently seven) candidate regions have been identified in a replicable manner by linkage studies. These regions are likely to host susceptibility genes for schizophrenia, but none of them has been identified up to now. Given these findings, polygenic transmission has now become very likely. The candidate regions are currently being narrowed down by various promising techniques.
    Notizen: Zusammenfassung Die Schizophrenie gehört zu den genetisch komplexen Erkrankungen, die keinem monogenen Erbgang folgen und bei denen auch nichtfamiliäre Umgebungsfaktoren eine wichtige Rolle spielen. Dabei wird intrafamiliär ein heterogener, quantitativ variierender Phänotyp übertragen, der zunehmend genauer charakterisiert werden kann. Keines der bekannten Gene mit vermuteter pathophysiologischer Relevanz spielt nach den bisherigen Erkenntnissen eine substantielle Rolle. In den vergangenen drei Jahren ist es aber erstmals durch Kopplungsuntersuchungen gelungen, mehrere replizierbare Kandidatenregionen (derzeit sieben) auf dem Genom zu identifizieren, in denen vermutlich Suszeptibilitätsgene für Schizophrenie liegen. Keines dieser Gene wurde jedoch bislang identifiziert. Mit diesen Befunden ist eine polygene Übertragung der Schizophrenie sehr wahrscheinlich geworden. Verschiedene Techniken zur Eingrenzung der Kandidatenregionen werden derzeit erfolgreich angewandt.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001150050524
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  • 35
    Digitale Medien
    Digitale Medien
    A mutation at codon 279 (N279K) in exon 10 of the Tau gene causes a tauopathy with dementia and supranuclear palsy (1999)
    Springer
    Acta neuropathologica 98 (1999), S. 62-77 
    Details
    ISSN: 1432-0533
    Schlagwort(e): Key words Frontotemporal dementia ; Genetics ; Progressive supranuclear palsy ; Tauopathy ; Exon ; amplifcation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Recently intronic and exonic mutations in the Tau gene have been found to be associated with familial neurodegenerative syndromes characterized not only by a predominantly frontotemporal dementia but also by the presence of neurological signs consistent with the dysfunction of multiple subcortical neuronal circuitries. Among families, the symptomatology appears to vary in quality and severity in relation to the specific Tau gene mutation and often may include parkinsonism, supranuclear palsies, and/or myoclonus, in addition to dementia. We carried out molecular genetic and neuropathological studies on two patients from a French family presenting, early in their fifth decade, a cognitive impairment and supranuclear palsy followed by an akinetic rigid syndrome and dementia. The proband died severely demented 7 years after the onset of the symptoms; currently, his brother is still alive although his disease is progressing. In both patients, we found a Tau gene mutation in exon 10 at codon 279, resulting in an asparagine to lysine substitution (N279K). Neuropathologically, widespread neuronal and glial tau accumulation in the cortex, basal ganglia, brain stem nuclei as well as in the white matter were the hallmark of the disease. These deposits were shown by immunohistochemistry and immunoelectron microscopy, using a battery of antibodies to phosphorylation-dependent and phosphorylation-independent epitopes present in multiple tau regions. In the neocortex, tau-immunopositive glial cells were more numerous than immunopositive neurons; the deeper cortical layers as well as the white matter adjacent to the cortex contained the largest amount of immunolabeled glial cells. In contrast, some brain stem nuclei contained more neurons with tau deposits than immunolabeled glial cells. The correlation of clinical, neuropathological and molecular genetic findings emphasize the phenotypic heterogeneitiy of diseases caused by Tau gene mutations. Furthermore, to test the effect of the N279K mutation and compare it with the effect of the P301L exon 10 mutation on alternative splicing of Tau exon 10, we used an exon amplification assay. Our results suggest that the N279K mutation affects splicing similar to the intronic mutations, allowing exon 10 to be incorporated more frequently in the Tau transcript.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s004010051052
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  • 36
    Digitale Medien
    Digitale Medien
    Analysis of potential phosphorylation sites in human T cell leukemia virus type 1 Tax (1999)
    Springer
    Journal of biomedical science 6 (1999), S. 206-212 
    Details
    ISSN: 1423-0127
    Schlagwort(e): Tax ; HTLV-1 ; Trans-activation ; Phosphorylation ; Mutagenesis ; Transcription ; Genetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract The human T cell leukemia virus type 1 (HTLV-1) Tax is a phosphoprotein, however, the contribution of phosphorylation to Tax activity is unknown. Previous studies have shown that phosphorylation of Tax occurs on serine residue(s), within one tryptic fragment, in response to 4β-phorbol-12β-myristate-13α-acetate, in both mouse and human cells. Studies were conducted in multiple cell lines to identify the specific phosphorylated serines as a prelude to functional analysis. The phosphorylation pattern of Tax was found to be different in 293T and COS-7 cells in comparison with MT-4 and Px-1 cells. However, one tryptic fragment remained consistent in comigration analyses among all cell lines. Using selected Tax serine mutants a tryptic fragment containing a serine at residue 113 believed to be the site of phosphorylation of Tax did not comigrate with the common phosphorylated tryptic fragment. Analysis of selected Tax mutants for ability totrans-activate the cytomegalovirus promoter demonstrated mutation of serine 77 to alanine reducedtrans-activation by 90% compared to wild-type Tax. However, examination of the phosphorylation pattern of the serine 77 mutant demonstrated that it is not the site of phosphorylation. These studies demonstrate the importance of using relevant cell lines to characterize the role of phosphorylation in protein function.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02255904
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  • 37
    Digitale Medien
    Digitale Medien
    Controlling septation in fission yeast: finding the middle, and timing it right (1999)
    Springer
    Current genetics 35 (1999), S. 571-584 
    Details
    ISSN: 1432-0983
    Schlagwort(e): Key words Cytokinesis ; Kinase ; Mitosis ; Schizosaccharomyces pombe ; Cell division ; Phosphatase ; Mutant ; Genetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The fission yeast Schizosaccharomyces pombe provides a simple eukaryotic model for the study of cytokinesis. S. pombe cells are rod-shaped, grow mainly by elongation at their tips, and divide by binary fission after forming a centrally placed division septum. Analysis of mutants has begun to shed light upon how septum formation and cytokinesis are regulated both spatially and temporally. Some of the proteins involved in these events have been functionally conserved throughout eukaryotic evolution, suggesting that aspects of this control will be common to all eukaryotic cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002940050455
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  • 38
    Digitale Medien
    Digitale Medien
    Clinical relevance of monosomy 22q11.2 in children with pulmonary atresia and ventricular septal defect (1999)
    Springer
    European journal of pediatrics 158 (1999), S. 302-307 
    Details
    ISSN: 1432-1076
    Schlagwort(e): Key words Congenital heart disease ; Pulmonary atresia and ventricular septal defect ; Genetics ; Monosomy 22q11.2
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The purpose of our study was to describe the prevalence and the clinical spectrum of monosomy 22q11.2 in a population of patients with pulmonary atresia and ventricular septal defect. We examined all 44 patients with this conotruncal cardiac malformation who presented to our institution from January 1994 until December 1997. The type of collateral lung perfusion was recorded including anomalies of the pulmonary arteries as well as facial and immunological abnormalities. Molecular-cytogenetic testing for a 22q11.2 microdeletion was performed using the probes D22S75 and cHKAD26. Statistical differences were evaluated with the Fisher's Exact Test. Monosomy 22q11.2 was present in ten children (23%) with major aortopulmonary collateral arteries (group 1). The remaining 13 children (29%) with major aortopulmonary collateral arteries (group 2) and all 21 children (48%) with ductus arteriosus (group 3) were negative for this microdeletion. All children in group 1 had facial anomalies, six had mild immunological abnormalities including decreased CD 4+ or CD 8+ cells. Anomalies of the pulmonary vascular bed were significantly more frequent in children of group 1 (9/10) than in children of group 2 (4/13) or group 3 (0/21). Due to these pulmonary vascular anomalies, corrective surgery had been accomplished in fewer children with monosomy 22q11.2 (none in group 1) as compared to 7/13 children in group 2 and 14/21 children in group 3. Conclusion In children with pulmonary atresia and ventricular septal defect, monosomy 22q11.2 is preferentially associated with major aortopulmonary collateral arteries. Due to the higher incidence of pulmonary arterial abnormalities, successful surgical repair will require a different therapeutic approach in most patients with this microdeletion.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s004310051077
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  • 39
    Digitale Medien
    Digitale Medien
    Linkage analysis of candidate myelin genes in familial multiple sclerosis (1999)
    Springer
    Neurogenetics 2 (1999), S. 155-162 
    Details
    ISSN: 1364-6753
    Schlagwort(e): Key words Multiple sclerosis ; Genetics ; Myelin basic protein ; Myelin oligodendrocyte glycoprotein ; Proteolipid protein
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: ABSTRACT Multiple sclerosis (MS) is an autoimmune demyelinating disease of the central nervous system. A complex genetic etiology is thought to underlie susceptibility to this disease. The present study was designed to analyze whether differences in genes that encode myelin proteins influence susceptibility to MS. We performed linkage analysis of MS to markers in chromosomal regions that include the genes encoding myelin basic protein (MBP), proteolipid protein (PLP), myelin-associated glycoprotein (MAG), oligodendrocyte myelin glycoprotein (OMGP), and myelin oligodendrocyte glycoprotein (MOG) in a well-characterized population of 65 multiplex MS families consisting of 399 total individuals, 169 affected with MS and 102 affected sibpairs. Physical mapping data permitted placement of MAG and PLP genes on the Genethon genetic map; all other genes were mapped on the Genethon genetic map by linkage analysis. For each gene, at least one marker within the gene and/or two tightly linked flanking markers were analyzed. Marker data analysis employed a combination of genetic trait model-dependent (parametric) and model-independent linkage methods. Results indicate that MAG, MBP, OMGP, and PLP genes do not have a significant genetic effect on susceptibility to MS in this population. As MOG resides within the MHC, a potential role of the MOG gene could not be excluded.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s100480050076
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  • 40
    Digitale Medien
    Digitale Medien
    Management of mantle cell lymphoma (1999)
    Springer
    Annals of hematology 78 (1999), S. 485-494 
    Details
    ISSN: 1432-0584
    Schlagwort(e): Key words Mantle cell lymphoma ; Classification ; Pathology ; Prognosis ; Immunology ; Genetics ; Antineoplastic agents ; Combined ; Therapeutic use ; Radiotherapy ; Hematopoietic stem cell transplantation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002770050545
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  • 41
    Digitale Medien
    Digitale Medien
    Why is acute leukemia more common in males? A possible sex-determined risk linked to the ABO blood group genes (1999)
    Springer
    Annals of hematology 78 (1999), S. 233-236 
    Details
    ISSN: 1432-0584
    Schlagwort(e): Key words Acute leukemia ; Genetics ; Sex ; ABO Blood group
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  Acute leukemia is more common in males at almost every age, and this fact remains unexplained. A study was carried out in northeast peninsular Malaysia, where the population is predominantly Malay, to examine whether there was a difference in ABO blood group distribution between males and females with acute leukemia (AL). The ABO blood groups of 109 male and 79 female patients with AL (98 ALL, 90 AML) were compared with those of 1019 controls. In the control population, 39.7% were group O. Among males with AL, 39.4% were group O, whereas among females with AL, the proportion was 24.1% (p=0.03). The same trend to a lower proportion of group O among females was seen if the group was divided into adult/pediatric or lymphoblastic/myeloblastic groups, though these differences were not statistically significant. If these findings can be confirmed, they suggest the presence of a "sex-responsive" gene near to the ABO gene locus on chromosome 9, which relatively protects group O women against AL, at least in our population. The existence of such a gene might also partly explain why acute leukemia, and possibly other childhood cancers, are more common in males.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002770050507
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  • 42
    Digitale Medien
    Digitale Medien
    The neurofibromatoses. An overview (1999)
    Springer
    Italian journal of neurological sciences 20 (1999), S. 89-108 
    Details
    ISSN: 1126-5442
    Schlagwort(e): Key words Neurofibromatosis ; Nf1 ; Nf2 ; Mosaic/segmental neurofibromatosis ; Variants ; Classification ; Neurological manifestations ; Genetics ; Childhood ; Adulthood
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The last two decades have seen clinical and molecular delineation of the different forms of neurofibromatosis. Differentiation of these forms is not just an academic exercise: their natural history, management and genetic counselling are quite different. Of the numerical classifications of neurofibromatosis proposed in the past, only neurofibromatosis type 1 (Nf1) and neurofibromatosis type 2 (Nf2) are now well delineated clinically and have been shown to be distinct at the molecular level. For both forms of neurofibromatosis, patients with clinical generalised disease have been demonstrated to be mosaic at the molecular level, and features of segmental or mosaic Nf1 and Nf2 have been delineated. Other reported forms of neurofibromatosis are rarer; they include Watson syndrome, hereditary spinal neurofibromatosis, familial intestinal neurofibromatosis, autosomal dominant café-au-lait spots alone, autosomal dominant neurofibromas alone, and schwannomatosis, the latter believed to be a variant of Nf2. Further delineation is neeeded for individuals having overlapping features of Noonan's syndrome and neurofibromatosis (the so-called Noonan/neurofibromatosis syndrome) and the syndrome of “multiple naevi, multiple schwannomas and multiple vaginal leiomyomas”. In this article we review the forms of neurofibromatosis which we believe are true clinical entities. Particular attention is given to the neurological manifestations of neurofibromatosis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s100720050017
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  • 43
    Digitale Medien
    Digitale Medien
    Insulin resistance and impaired insulin secretion due to phosphofructo-1-kinase-deficiency in humans (1999)
    Springer
    Journal of molecular medicine 77 (1999), S. 96-103 
    Details
    ISSN: 1432-1440
    Schlagwort(e): Key words Diabetes ; Genetics ; Phosphofructokinase ; Glycogenosis ; NIDDM ; PFK
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The etiology of non-insulin-dependent diabetes mellitus (NIDDM) is usually explained as a combination of peripheral insulin resistance and impaired beta-cell function. Phosphofructo-1-kinase (PFK1) is a rate limiting enzyme in glycolysis, and its muscle subtype (PFK1-M) deficiency leads to an autosomal recessively inherited disorder known as glycogenosis type VII or Tarui’s disease. It was evaluated whether PFK1-M deficiency leads to NIDDM in humans. A core family of four was evaluated for PFK1-M deficiency by DNA- and enzyme-activity-analyses. All members underwent oral and intravenous glucose tolerance test (oGTT/ivgtt), as well as an insulin sensitivity test (IST) using octreotide. Results: Father (46 years, BMI 22.4 kg/m2) and older son (19 years, BMI 17.8 kg/m5) showed homozygous PFK1-M deficiency, while mother (47 years, BMI 28.4 kg/m5) and younger son (13 years, BMI 16.5 kg/m5) were shown to be heterozygously PFK1-M-deficient on enzyme activity levels. DNA analysis revealed an exon 5-missense-mutation at one allele of all four members, and an exon 22-frameshift-mutation at the other allele of the two homozygously affected individuals. By oGTT the father showed impaired glucose tolerance, and the mother clinical diabetes. By ivGTT both parents and the older son had a decreased first phase insulin secretion, and a diminished glucose disappearance rate. The IST showed marked insulin resistance in both parents and the older son, and moderate resistance in the younger son, previously not described. Conclusion: PFK1-M-deficiency leads to a metabolic state typical for early NIDDM in homozygously affected humans, especially concerning insulin resistance and loss of first phase beta-cell insulin secretion, and may contribute to the manifestation of NIDDM in a subgroup of patients.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001090050311
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  • 44
    Digitale Medien
    Digitale Medien
    Polymorphisms in the glutamate transporter gene EAAT2 in European ALS patients (1999)
    Springer
    Journal of neurology 246 (1999), S. 1140-1144 
    Details
    ISSN: 1432-1459
    Schlagwort(e): Key words Amyotrophic lateral sclerosis ; Genetics ; Glutamate transporter gene
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Amyotrophic lateral sclerosis (ALS) is a progressive neurological disorder characterised by degeneration of upper and lower motor neurons. Whilst the primary pathogenic trigger is unknown in most cases, evidence is mounting to implicate a role for glutamate-mediated neurotoxicity in the disorder. Recent studies have shown reduced levels of the mainly astroglial glutamate transporter EAAT2 in ALS motor cortex and spinal cord and multiple abnormal EAAT2 mRNA species in ALS brain tissue. One cause of the low EAAT2 levels may be that point mutations in the EAAT2 gene, EAAT2, result in an abnormal unstable protein. To test this hypothesis we analysed EAAT2 in 128 sporadic and 23 familial European ALS cases. No variants within the coding sequence of EAAT2 to affect the protein sequence nor in the consensus splice sites of the flanking intronic sequences were found in any cases, similar to findings in other reports. Frequent polymorphisms within the flanking intronic sequences of both exons 2 and 4 were seen but at similar frequencies in controls. Mechanisms other than mutations within the coding region of EAAT2 must therefore be responsible for the low levels of EAAT2 seen in most cases of ALS.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s004150050532
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  • 45
    Digitale Medien
    Digitale Medien
    Early diagnosis and the clinical genetics of Alzheimer’s disease (1999)
    Springer
    Journal of neurology 246 (1999), S. 69-72 
    Details
    ISSN: 1432-1459
    Schlagwort(e): Key words Alzheimer’s disease ; Genetics ; Genetic counseling ; Predictive testing ; Diagnosis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Alzheimer’s disease (AD) has a significant genetic background manifested as autosomal dominant inheritance in some early-onset families and as familial risk in late-onset cases. Three genes responsible for early-onset autosomal dominant AD have been identified, and one gene, apolipoprotein E, has been confirmed as a susceptibility gene for late-onset forms of the disorder. These findings raise the possibility of genetic testing, either for early diagnosis or prediction. For early-onset autosomal dominant AD genetic testing will have a limited but useful role in confirming diagnosis in established cases and in predictive counselling for relatives; a situation analogous to that for Huntington’s disease. For late-onset AD significant problems remain to be overcome before the advances in molecular genetics have a direct clinical application
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s004150050310
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  • 46
    Digitale Medien
    Digitale Medien
    Self-incompatibility in passion fruit: evidence of two locus genetic control (1999)
    Springer
    Theoretical and applied genetics 98 (1999), S. 564-568 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Key words Passiflora ; Self-incompatibility ; Genetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  The self-incompatibility in yellow passion fruit was previously described as homomorphic sporophytic with monofactorial inheritance. Five progenies were obtained by bud-selfing. The plants of these progenies were selfed, reciprocally crossed within each progeny and crossed with known incompatible phenotypes to identify their phenotypic group. Fruit set was evaluated at the 7th day after pollination. Two progenies consisted of two self-incompatible groups, the other three formed three suck groups. The groups were identified as S1, S2, S3, S4, S5 and S6. The results provide evidence that the self-incompatibility of passion fruit is controlled by two loci, the S-gene and another, whose expression needs to be investigated.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001220051105
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  • 47
    Digitale Medien
    Digitale Medien
    A stylar ribonuclease assay to detect self-compatible seedlings in almond progenies (1999)
    Springer
    Theoretical and applied genetics 99 (1999), S. 800-810 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Key words Almond ; Compatibility ; Genetics ; Prunus dulcis ; Ribonucleases
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  Six almond progenies, each the product of a cross between a self-compatible and a self-incompatible parent, were analysed for stylar ribonucleases. Proteins were extracted and separated using non-equilibrium pH gradient electrofocusing (NEPHGE), and the gels were stained for ribonuclease activity. Most seedlings showed either two principal bands, interpreted as corresponding to two incompatibility alleles, or a single band. The seedlings were also bagged in the field at flowering time to determine fruit set after selfing, and some were also examined for the growth of pollen-tubes in selfed styles using UV fluorescence microscopy. With very few exceptions, those seedlings showing single-banded zymograms were found to be self-compatible according to field and microscope studies, and those with two bands were found to be self-incompatible. We conclude that the allele for self-compatibility in almond does not code for ribonuclease activity and that the ribonuclease isoenzyme assay is a convenient technique for predicting self-compatibility in segregating progenies. A novel band in two derivatives of ’Ferrastar’ was ascribed to a new incompatibility allele, S 10 .
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001220051299
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  • 48
    Digitale Medien
    Digitale Medien
    Craniosynostosis: from a clinical description to an understanding of bone formation of the skull (1999)
    Springer
    Child's nervous system 15 (1999), S. 676-680 
    Details
    ISSN: 1433-0350
    Schlagwort(e): Key words Craniosynostosis ; Genetics ; FGFR ; Msx2 ; Development ; Skull
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  The genetic studies of syndromic craniosynostoses lead to the characterisation of genes that regulate the correct development of the bones of the skull. From these studies, it appears that FGF/FGFR signalling has a crucial role in this problem. Numerous mutations affecting the genes coding for FGFR1, 2 or 3 are responsible for these syndromes. It is interesting to note that some identical mutations produced various different phenotypes, suggesting that other genes modulate the phenotypic expressivity. The other involved genes in these syndromes code for such proteins as Msx2 or Twist that interact in the cellular pathways responsible for FGF action. From these genetic studies, it is now important to establish the role of these proteins during the development of the skull. Msx2 plays a repressive role in osteogenesis, whereas FGFRs act as promoting proteins. In the near future, it will be very important to improve our understanding of these phenomena in order to test specific treatments to prevent the development of such syndromes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s003810050457
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  • 49
    Digitale Medien
    Digitale Medien
    Division of labor in a dynamic environment: response by honeybees (Apis mellifera) to graded changes in colony pollen stores (1999)
    Springer
    Behavioral ecology and sociobiology 46 (1999), S. 171-179 
    Details
    ISSN: 1432-0762
    Schlagwort(e): Key words Honeybee ; Apis mellifera ; Division of labor ; Genetics ; Pollen foraging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  A fundamental requirement of task regulation in social groups is that it must allow colony flexibility. We tested assumptions of three task regulation models for how honeybee colonies respond to graded changes in need for a specific task, pollen foraging. We gradually changed colony pollen stores and measured behavioral and genotypic changes in the foraging population. Colonies did not respond in a graded manner, but in six of seven cases showed a stepwise change in foraging activity as pollen storage levels moved beyond a set point. Changes in colony performance resulted from changes in recruitment of new foragers to pollen collection, rather than from changes in individual foraging effort. Where we were able to track genotypic variation, increases in pollen foraging were accompanied by a corresponding increase in the genotypic diversity of pollen foragers. Our data support previous findings that genotypic variation plays an important role in task regulation. However, the stepwise change in colony behavior suggests that colony foraging flexibility is best explained by an integrated model incorporating genotypic variation in task choice, but in which colony response is amplified by social interactions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002650050607
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  • 50
    Digitale Medien
    Digitale Medien
    Erbliche Ursachen und Risikofaktoren der Alzheimer-Krankheit (1999)
    Springer
    Der Nervenarzt 70 (1999), S. 195-205 
    Details
    ISSN: 1433-0407
    Schlagwort(e): Schlüsselwörter Alzheimer-Krankheit ; Genetik ; Risikofaktoren ; Genetische Beratung ; Key words Alzheimer’s disease ; Genetics ; Risk factors ; Genetic counseling
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Summary A multifactorial etiology underlies the majority of cases of Alzheimer’s disease (AD). Both ill-defined environmental and genetic factors contribute to the development of the disease. Allele ɛ4 of ApoE is a genetic risk factor. Its presence increases the risk of developing AD. However, presence of e4 is neither necessary nor sufficient for the disease to arise. Apart from the common multifactorial forms of the disease, there are rare variants which are inherited as Mendelian traits. To date three genes are known that can be mutated in these rare forms of AD. Of these, mutations in the gene presenilin 1 on chromosome 14 are most frequent. In addition, mutations in the gene presenilin 2 on chromosome 1 and in the amyloid precursor protein gene (APP on chromosome 21) occur in autosomal dominant AD. This article reviews our present knowledge of the genetics of AD and discusses its relevance for patients with AD and their relatives.
    Notizen: Zusammenfassung Der Großteil der Fälle von Alzheimer-Krankheit (AK) hat eine multifaktorielle Ätiologie. Das bedeutet, bisher nicht genauer bekannte Umwelteinflüsse und genetische Faktoren spielen bei der Entwicklung der Krankheit eine wesentliche Rolle. Von seiten der Genetik unterscheidet man bei der AK gegenwärtig genetische Risikofaktroren und Mutationen. Der einzige bisher gesicherte genetische Risikofaktor ist das Allel ɛ4 des Gens für Apolipoprotein E auf Chromosom 19. Dieses Allel erhöht die Wahrscheinlichkeit, an der AK zu erkranken, ist jedoch weder eine notwendige noch eine hinreichende Bedingung. Neben den häufigen Formen mit multifaktorieller Ätiologie kommen seltene Varianten der Krankheit vor, die nach Mendelschen Regeln vererbt werden. Bisher sind 3 Gene bekannt, die bei diesen seltenen, in der Regel früh auftretenden und autosomal dominant vererbten Formen mutiert sein können. Am häufigsten findet sich bei den autosomal-dominanten Fällen eine Mutation im Gen präsenilin 1 auf Chromosom 14, seltener liegen Mutationen im Gen präsenilin 2 auf Chromosom 1 und im Gen des Amyloid- Vorläuferproteins auf Chromosom 21 vor. In diesem Beitrag geben wir eine Übersicht über gegenwärtige Befunde zur Genetik der AK und diskutieren die Bedeutung dieses Wissens für Patienten und deren Verwandte.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001150050423
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  • 51
    Digitale Medien
    Digitale Medien
    Crosses between diabetic BB/OK and wild rats confirm that a third gene is essential for diabetes development (1998)
    Springer
    Acta diabetologica 35 (1998), S. 109-111 
    Details
    ISSN: 1432-5233
    Schlagwort(e): Key words BB rat ; Diabetes ; Genetics ; Crossing study
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Several crossing studies with diabetic BB rats have shown that in addition to the lymphopenia (Iddm1) and the MHC class II genes of the RT1u haplotype (Iddm2) there are further non-MHC genes essential for diabetes development. Because diabetes-resistant inbred rat strains may be homozygous for one of the diabetogenic non-MHC genes, masking the expression of diabetogenic genes and leading to an underestimation of the number of diabetogenic genes, we crossed wild and diabetic BB/OK rats. The F1 hybrids were backcrossed onto diabetic female (BC1W-F, n=97) and male BB/OK rats (BC1W-M, n=98) transferred to a specified-pathogen-free environment and studied for the frequency and age at onset of diabetes up to an age of 30 weeks. Comparing the results of these BC1 W hybrids with similarly derived hybrids using diabetes-resistant DA rats (BC1DA-F, n=113; BC1DA-M, n=216), the diabetes frequency in total was comparable indicating the action of three recessive genes. The percentage of diabetics in Iddm1 and Iddm2 homozygotes confirmed the existence of the third gene, Iddm3, but there were some sex differences; significantly more male than female BC1W-F and significantly more BC1DA-M than BC1DA-F males were diabetic. Regarding the age at onset, the BC1W-F hybrids manifested not only significantly earlier, but also more uniformly than BC1DA-F and BC1-M hybrids.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s005920050114
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  • 52
    Digitale Medien
    Digitale Medien
    Hepatocyte nuclear factor-1a gene and non-insulin-dependent diabetes mellitus in the Japanese population (1998)
    Springer
    Acta diabetologica 35 (1998), S. 150-153 
    Details
    ISSN: 1432-5233
    Schlagwort(e): Key words Non-insulin-dependent diabetes mellitus ; MODY ; Hepatocyte nuclear factor-1α ; Genetics ; Microsatellite polymorphism
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Recently, hepatocyte nuclear factor-1α (HNF-1α, which is encoded by the TCF1 gene) mutations were reported in a subset of patients with maturity onset diabetes of the young (MODY3). We studied the contribution of TCF1 to genetic susceptibility to common non-insulin-dependent diabetes mellitus (type 2) in Japanese subjects by investigating allelic association with type 2 diabetes use of three markers. We also studied the frequency of the G191D mutation, the only mutation of TCF1 reported so far in late-onset type 2 diabetes. A total of 356 subjects were studied. There were no significant differences in allele frequency of the three markers between patients with type 2 diabetes and control subjects. A G191D mutation was not found in the subjects studied, giving a frequency of less than 0.4% in common type 2 diabetes. The lack of association of type 2 diabetes with three markers in and near TCF1 suggests that mutations in TCF1 derived from a limited number of founders are not a major cause of common type 2 diabetes even in the genetically homogeneous Japanese population. The data also indicate that the G191D mutation in TCF1 plays little, if any, role in susceptibility to common type 2 diabetes in the Japanese.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s005920050120
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  • 53
    Digitale Medien
    Digitale Medien
    The effect of genotype on response thresholds to sucrose and foraging behavior of honey bees (Apis mellifera L.) (1998)
    Springer
    Journal of comparative physiology 182 (1998), S. 489-500 
    Details
    ISSN: 1432-1351
    Schlagwort(e): Key words Honey bee ; Behavior ; Genetics ; Neurobiology ; Foraging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Honey bee foragers were tested for their proboscis extension response (PER) to water and varying solutions of sucrose. Returning pollen and nectar foragers were collected at the entrance of a colony and were assayed in the laboratory. Pollen foragers had a significantly higher probability of responding to water and to lower concentrations of sucrose. Bees derived from artificially selected high- and low-pollen-hoarding strains were also tested using the proboscis extension assay. Returning foragers were captured and tested for PERs to 30% sucrose. Results demonstrated a genotypic effect on PERs of returning foragers. The PERs of departing high- and low-strain foragers were consistent with those of returning foragers. The PERs were related to nectar and water reward perception of foragers. High strain bees were more likely to return with loads of water and lower concentrations of sucrose than foragers from the low pollen strain. Low-strain bees were more likely to return empty. We identified a previously mapped genomic region that contains a variable quantitative trait locus that appears to influence sucrose response thresholds. These studies demonstrate a gene-brain-behavior pathway that can be altered as a consequence of colony-level selection for quantities of stored food.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s003590050196
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  • 54
    Digitale Medien
    Digitale Medien
    Genetics of psoriasis (1998)
    Springer
    Archives of dermatological research 290 (1998), S. 463-476 
    Details
    ISSN: 1432-069X
    Schlagwort(e): Key words Psoriasis ; Genetics ; HLA ; Linkage ; Epidemiology
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Non-pustular psoriasis consists of two disease subtypes, type I and type II, which demonstrate distinct characteristics. Firstly the disease presents in different decades of life, in type I before the age of 40 years and later in type II. Secondly, contrasting frequencies of HLA alleles are found: type I patients express predominantly HLA-Cw6, -B57, and -DR7, whereas in type II patients HLA-Cw2 is overrepresented. Finally, familial inheritance is found in type I but not in type II psoriasis. The study of concomitant diseases in psoriasis contributes to deciphering the distinct patterns of the disease. Defence against invading microorganisms seems better developed in psoriatics than in controls. This evolutionary benefit may have caused the overall high incidence of psoriasis of 2%. Psoriasis is a multifactorial and heterogenetically inherited disease. The heterogeneity is evident by the diversity of genetically linked markers. The multifactorial component results from the observation of external trigger mechanisms, such as the Koebner phenomenon, stress and the intake of certain drugs. Twin studies have shown that environmental factors contribute to the onset of the disease. In type I psoriasis, special extended haplotypes such as EH57.1 (HLA-Cw6-B57-DRB1*0701-DQA1*0201-DQBl*0303) and EH65.1 (HLA-Cw8-B65-DRB1*0102-DQB1*0501) have been found to be increased. The application of microsatellite techniques has identified distinct positions on several chromosomes at which putative psoriasis genes may be located. Disease susceptibility genes are thought to be present on chromosomes 4q, 6p, 16q, 17q and 20p. Moreover, on chromosome 1q, genes regulating epidermal differentiation have been identified. Linkage to this area has been proposed. Furthermore, psoriasis gene loci on chromosomes 2, 8 and 20 have been suggested.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s004030050338
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  • 55
    Digitale Medien
    Digitale Medien
    Recent advances in genetic research on schizophrenia (1998)
    Springer
    Journal of biomedical science 5 (1998), S. 28-30 
    Details
    ISSN: 1423-0127
    Schlagwort(e): Genetics ; Schizophrenia
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Evidence for genetic factors in schizophrenia is reviewed with regard to family, twin and adoption studies, and recent advances in molecular genetic technology are applied to explore possible gene loci susceptible to schizophrenia. Application of neuropsychological and neuroimaging methodologies are also reviewed with an aim to develop criteria for defining phenotypes for genetic studies.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02253353
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  • 56
    Digitale Medien
    Digitale Medien
    Prediction of febrile seizures in siblings: a practical approach (1998)
    Springer
    European journal of pediatrics 157 (1998), S. 340-344 
    Details
    ISSN: 1432-1076
    Schlagwort(e): Key words Febrile seizures ; Genetics ; Family ; Risk factors
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract To quantify the risk of febrile seizures (FS) in relatives of children with FS and to predict the risk of FS in siblings, we calculated cumulative risks of FS in first degree relatives of 129 children with FS. The study was conducted as a prospective follow up study of FS recurrences at the outpatient clinic of the Sophia Children's Hospital in Rotterdam. Thirteen parents and 12 siblings had experienced FS, accounting for a 6-year cumulative risk of 7%. The risk of FS was increased in relatives of children with recurrent FS (12%). The risk of FS in siblings (10%) in our study was more than twice the average risk in a similar population (4%). A positive FS history in a parent, young age at onset in the proband, and recurrences in the proband were selected in a multivariable prediction model. If two or more of these risk factors were present, the risk of West European siblings to develop FS was 46% (hazard ratio 5.4). Conclusion The cumulative risk of FS in siblings of children with FS is increased. The age attained risk of FS can be estimated using a practical model incorporating three readily available risk factors.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s004310050824
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  • 57
    Digitale Medien
    Digitale Medien
    Paternal age is a risk factor for Alzheimer disease in the absence of a major gene (1998)
    Springer
    Neurogenetics 1 (1998), S. 277-280 
    Details
    ISSN: 1364-6753
    Schlagwort(e): Key words Alzheimer disease ; Risk factors ; Parental age ; Genetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: ABSTRACT We compared the parental age at birth of patients with Alzheimer disease (AD) with that of cognitively healthy control subjects. Within 206 carefully diagnosed AD patients, two groups were distinguished according to the likelihood of carrying a major gene for AD (MGAD). This likelihood was calculated by applying a Bayesian approach which incorporates data on aggregation of the disease, age at onset, and "censoring" ages within the family. All AD patients were ranked by MGAD probability. According to the sample's quartiles, two subgroups were defined representing the 52 individuals with the lowest and the 52 with the highest MGAD probability. Age at onset of dementia, education, and apolipoprotein E ε  4 allele frequencies were not statistically different between the two groups. Fathers of patients with a low MGAD probability were significantly older (35.7±8.1 years) than fathers of both other groups (high MGAD probability 31.3±6.9 years, P =0.004; controls 32.6±6.8 years, P =0.04, n=50). The differences for mothers were less pronounced and not statistically significant. These findings suggest that increased paternal age is a risk factor for AD in the absence of a major gene, whereas increased maternal age and AD are associated only weakly and independently of genetic disposition.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s100480050041
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  • 58
    Digitale Medien
    Digitale Medien
    Recent progress in the genetics of human epilepsies (1998)
    Springer
    Neurogenetics 1 (1998), S. 153-163 
    Details
    ISSN: 1364-6753
    Schlagwort(e): Key words Epilepsy ; Genetics ; Linkage
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: ABSTRACT Despite several lines of evidence indicating a strong genetic influence in the etiology of idiopathic epilepsies, progress in the mapping and identification of human epilepsy genes has been limited until recently. In addition to the localisation and/or isolation of several genes causing progressive epilepsies associated with cerebral degeneration, at least seven human genomic regions (6p, 8q, 10q, 15q, 16p, 19q, 20q) are now known to harbour genes implicated in idiopathic epilepsies. In the case of nocturnal frontal lobe epilepsy, mutations in a nicotinic acetylcholine receptor subunit gene have been identified. Systematic studies of rare epileptic disorders inherited as monogenic Mendelian traits, as well as studies on more complex polygenic idiopathic epilepsies, are still needed in order to identify all the epilepsy genes. This will allow better diagnosis and genetic counseling in families of affected individuals, a better understanding of both the pathophysiology of epilepsies and normal brain functioning, and the design of new pharmacological and genetic therapies.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s100480050024
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  • 59
    Digitale Medien
    Digitale Medien
    Microsatellite DNA in Actinidia chinensis: isolation, characterisation, and homology in related species (1998)
    Springer
    Theoretical and applied genetics 97 (1998), S. 1269-1278 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Key words Simple sequence repeat (SSR) ; Microsatellites ; Molecular markers ; Genetics ; Kiwifruit
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  We have isolated and sequenced 263 microsatellite-containing clones from two small insert libraries of Actinidia chinensis enriched for (AC/GT) and (AG/CT) repeats, respectively. Primer pairs were designed for 203 microsatellite loci and successfully amplified from both plasmid and A. chinensis genomic DNA. In this paper we report the sequences of 40 primer pairs for which we have demonstrated Mendelian segregation in the progeny from controlled crosses. The polymorphism of ten microsatellites of each type was evaluated in four diploid and six tetraploid genotypes of A. chinensis. All microsatellites proved to be polymorphic, the number of alleles per locus detected in polyacrylamide sequencing gels ranging from 9 to 17. The high degree of polymorphism in Actinidia renders these markers useful either for mapping in A. chinensis or for fingerprinting cultivars of both domesticated kiwifruit species (A. chinensis and A. deliciosa). While most primer pairs produced single amplification products, about 20% generated banding patterns consistent with the amplification of two different loci. This supports the hypothesis that diploid species of Actinidia (2n=2x=58) are polyploid in origin with a basic chromosome number x=14/15 and that chromosome duplication may have occurred during the evolution of the genus. Finally, we have assayed the cross-species transportability of primer pairs designed from A. chinensis sequences and have found extensive cross-species amplification within the genus Actinidia; 75% of primer pairs gave successful amplification in the eight species assayed (A. arguta, A. rufa, A. polygama, A. chrysantha, A. callosa, A. hemsleyana, A. eriantha, and A. deliciosa), which are representative of the four sections into which the genus is currently split.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001220051019
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  • 60
    Digitale Medien
    Digitale Medien
    Fruit tree genetics at a turning point: the almond example (1998)
    Springer
    Theoretical and applied genetics 96 (1998), S. 588-601 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Key words Fruit trees ; Genetics ; Almond ; Prunus amygdalus ; Breeding
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  The large size and the long generation time of fruit trees generally reduce the possibilities of obtaining genetic information on the transmission and heritability of useful agronomic traits in these species. However, from breeding work carried out with fruit trees, an important amount of data is now available, although large differences are apparent among the different species. There is not much information known about almond compared to what is available on other Prunus fruit species, but more data have been accumulated on it than on most of the other nut trees, thus making almond special among all the temperate fruit and nut species. Only five qualitative traits have been described in almond, with an additional two also possibly qualitative. Heritabilities have been estimated for an important number of quantitative traits, mainly phenological times and fruit characters. Important information is available on molecular markers, including enzymes, RFLPs, RAPDs and other recently developed markers. Linkages, however, have only been established among molecular markers, allowing accurate genetic maps to be built but not yet enabling agronomical characters to be located in these maps, probably because the latter have not been sufficiently studied. The effectiveness of the application of genetic maps in plant breeding will depend on the accuracy of the study of different agronomic traits and their expression, implying more field work and recognition of this work. Ultimately, any new fruit cultivar has to be grown in the field and has to allow the grower to make a profit.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001220050777
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  • 61
    Digitale Medien
    Digitale Medien
    Cytological basis for a tetraspory in Cupressus sempervirens L. megagametogenesis and its implications in genetic studies (1998)
    Springer
    Theoretical and applied genetics 96 (1998), S. 776-779 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Key words Cupressus sempervirens ; Cytology ; Megasporogenesis ; Megagametogenesis ; Genetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  The processes of megasporogenesis and early megagametogenesis were cytologically investigated in Cupressus sempervirens L. in order to elucidate, at the cellular level, the origin of the megagametophyte. After pollination, sporogenous tissue developed in the chalazal region of the nucellus, but only one megaspore mother cell differentiated and divided meiotically without cell-wall formation. This led to the development of a cell with four nuclei which directly functioned as a megaspore. The C. sempervirens megagametophyte is thus tetrasporic, in contrast to the majority of conifers where the megagametophyte is monosporic. The consequenses of this observation are discussed from a genetics point of view.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001220050801
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  • 62
    Digitale Medien
    Digitale Medien
    Patient regrets after bilateral prophylactic mastectomy (1998)
    Springer
    Annals of surgical oncology 5 (1998), S. 603-606 
    Details
    ISSN: 1534-4681
    Schlagwort(e): Breast cancer ; Genetics ; Prophylactic mastectomy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Background: The discovery of a cadre of breast cancer susceptibility genes has resulted in an increase in the number of women seeking information about prophylactic breast surgery, but virtually no large-scale prospective databases exist to assist women considering prophylactic mastectomy. Methods: The authors constructed a National Prophylactic Mastectomy Registry comprised of a volunteer population of 817 women from 43 states who have undergone prophylactic mastectomy. Results: In the registry, 370 women had undergone bilateral prophylactic mastectomy. Twenty-one (5%) women expressed regrets about the procedure. The median follow-up was 14.6 years (mean 14.8 years; range 0.2–51 years). Those with regrets were subsetted into those with major (n=10) or minor (n=7) regrets. Regrets were more common in those women with whom discussion about prophylactic mastectomy was initiated by a physician (19/255), compared with patients who initiated the discussion themselves (2/108;P〈.05). Conclusions: The overall satisfaction rate of 95% reported here may be explained by the voluntary nature of this registry. The most important factor that predicts an unfavorable outcome following bilateral prophylactic mastectomy is a physician-initiated discussion.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02303829
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  • 63
    Digitale Medien
    Digitale Medien
    Autosomal recessive polycystic kidney disease (1998)
    Springer
    Journal of molecular medicine 76 (1998), S. 303-309 
    Details
    ISSN: 1432-1440
    Schlagwort(e): Key words Autosomal recessive polycystic kidney disease ; Linkage study ; Genetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  Autosomal recessive polycystic kidney disease (ARPKD) is a rare inherited disorder which usually becomes clinically manifest in early childhood, although the spectrum of ARPKD is much more variable than generally known. Presentation of ARPKD at later ages and survival into adulthood have been observed in many cases. The responsible gene has been mapped to chromosome 6p. Thus there is no evidence of genetic heterogeneity. The most important indication for DNA diagnosis is the prenatal diagnosis in families with at least one affected child. The critical region has been narrowed with the use of recombinant families of about 4 cM. Several possible candidate genes have been excluded.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s001090050221
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  • 64
    Digitale Medien
    Digitale Medien
    The possibilities of modeling neural networks in the framework of the thermodynamics of genetically disordered systems (glasses) (1998)
    Springer
    Journal of biological physics 24 (1998), S. 41-58 
    Details
    ISSN: 1573-0689
    Schlagwort(e): Neural networks ; Associative memory ; Brain functions ; Disordered systems ; Genetics ; Synergetics ; Self-organization ; Vitreous state
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Physik
    Notizen: Abstract Non-spin glasses possess a number of specific features which, in structural and dynamic aspects, are close to conditions necessary for neural networks to function. In a disordered network there exists a plurality of structural parameters and a number of two-level states defined by double-well potentials. Their characteristics are specified by the conditions of glass formation, i.e. by genesis. The thermodynamic description of glass as a self-organizing system (that does not require introducing an interacting potential model) leads to an unambiguous conclusion that its frequency spectrum is predetermined by the structure, which is characterized by zero-point entropy. Glass is a natural system of oscillators which form a disordered network. In this sense, glass conforms to a known model of a disordered neural network formed by interconnected oscillators. If one assumes that in living organisms the structure of a neural network (the brain) is inherited according to a genetic mechanism, the quickness of learning and recognition of patterns, the stability of associative memory and other capabilities have to be inherited genetically. The more ordered a neural network formed by distinguishable neurons, the better its capabilities.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1005071706864
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  • 65
    Digitale Medien
    Digitale Medien
    Genetic and Shared Environmental Influences on Adolescent BMI: Interactions with Race and Sex (1998)
    Springer
    Behavior genetics 28 (1998), S. 265-278 
    Details
    ISSN: 1573-3297
    Schlagwort(e): Genetics ; body mass index ; adolescents ; race ; sex
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Psychologie
    Notizen: Abstract The present study uses a behavioral genetic design to investigate the genetic and environmental influences on variation in adolescent body mass index (BMI) and to determine whether the relative influences of genetic and environmental factors on variation in BMI are similar across racial groups and sexes. Data for the present study come from the National Longitudinal Study on Adolescent Health (Add Health), a large, nationally representative study of adolescent health and health-related behaviors. The Add Health sample contains a subset of sibling pairs that differs in levels of genetic relatedness, making it well suited for behavioral genetics analyses. The present study examines whether genetic and environmental influences on adolescent BMI are the same for males and females and for Black and White adolescents. Results indicate that genetic factors contribute substantially to individual differences in adolescent BMI, explaining between 45 and 85% of the variance in BMI. Furthermore, based on an analysis of opposite-sex sibling pairs, the genes that influence variation in adolescent BMI are similar for males and females. However, the relative importance of genetic and environmental influences on variation in BMI differs for males and females and for Blacks and Whites. Although parameter estimates could be constrained to be equal for Black and White males, they could not be constrained to be equal for Black and White females. Moreover, the best-fitting model for Black females was an ADE model, for White females it was an ACE model, and for males it was an AE model. Thus, shared environmental influences are significant for White female adolescents, but not for Black females or males. Likewise, nonadditive genetic influences are indicated for Black females, but not for White females or males. Implications of these results are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1021619329904
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  • 66
    Digitale Medien
    Digitale Medien
    Neuronal ceroid lipofuscinoses: a review (1998)
    Springer
    Neurological sciences 19 (1998), S. 271-276 
    Details
    ISSN: 1590-3478
    Schlagwort(e): Neuronal ceroid lipofuscinosis ; Clinical features ; Classification ; Diagnosis ; Genetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Sommario Le ceroido lipofuscinosi neuronali (NCL) sono tra le encefalopatie progressive più freguenti nell'infanzia ed interessano, seppure più raramente, l'adulto. Clinicamente sono caratterizzate da demenza, deficit visivo, epilessia e disturbi motori. Gli aspetti patologici specifici sono rappresentati da degenerazione neuronale ed accumulo lisosomiale di lipopigmento in differenti tipi cellulari. Il difetto biochimico della malattia non e noto. La classificazione delle NCL, basata su criteri clinici, distingue sei forme classiche ed altre forme atipiche. L'elettrofisiologia e la neuroradiologia sono di importante ausilio diagnostico, ma la diagnosi si fonda sull'identificazione dell'accumulo di lipopigmento the presenta pattern ultrastrutturali specifici. Differenti difetti genetici sono stati dimostrati in diverse forme cliniche, ma il meccanismo patogenetico molecolare rimane ancora da chiarire.
    Notizen: Abstract Neuronal ceroid lipofuscinoses (NCLs) are among the most common neurodegenerative diseases in childhood but rarely present in adulthood. The main symptoms are psychomotor deterioration, visual failure, epilepsy and motor disturbances. The NCLs are morphologically characterized by the accumulation of lipopigments within numerous cell types and loss of neurons. Pathogenesis is unknown. The current clinical classification recognizes six classic types of NCL and several atypical forms. Electrophysiological and neuroradiological findings may be of diagnostic significance, but disease recognition rests on the demonstration of a typical ultrastructural pattern. Genetic studies have demonstrated that several different genetic loci are involved in the pathogenesis of NCL, but the molecular mechanisms underlying neuronal death and lipopigment accumulation are not understood.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00713852
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  • 67
    Digitale Medien
    Digitale Medien
    Synthesis, homopolymerization, and block copolymerization of N-ethyl-2-ethynyl-pyridinium trifluoromethanesulfonate with styrene and butadiene (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 703-712 
    Details
    ISSN: 0887-624X
    Schlagwort(e): synthesis ; homopolymerization ; block copolymerization ; N-ethyl-2-ethyl-pyridinium ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A novel acetylenic monomer 2-N-ethyl pyridinium trifluoromethane sulfonate (2EPyEtTf) was synthesized and polymerized. Diblock copolymers of 2EPyEtTf with styrene and with butadiene were prepared. Initiation of the polymerization by living anionic polystyryl--Li+ and polybutadienyl--Li+ (Scheme 1) resulted in polystyrene-block-poly(N-ethyl-2-ethynylpyridinium trifluoromethanesulfonate) (PS57PA8), and polybutadiene -block-poly(N-ethyl-2-ethynylpyridinium trifluoromethanesulfonate) (PB30PA8). These amphiphilic block molecules contain rigid, conjugated, and strongly hydrophilic polyacetylene chain fragments attached to hydrophobic polystyrene or flexible polybutadiene chain fragments. The structure of these copolymers was studied by FTIR, UV-visible, and NMR spectroscopy. GPC and viscometry were also used to obtain information on the molecular mass and the molecular mass distribution. Thermal behavior was investigated by means of TGA and DSC. Both block copolymers were shown to form stable monolayers at the air-water interface. The positively charged rigid polyacetylene portion of the copolymer is believed to be partially submerged, while the more flexible hydrophobic chains are forced out of the water. Multilayers of PB30PA8 deposited using the Langmuir-Blodgett technique were found to be less uniform than in the case of the previously reported polystyrene-block-poly(2EPyMeTf) (PS12PA4) copolymer (Balogh et al., Macromolecules, 29, 1996). Polycation-polyanion self-assembly deposition was also investigated, using polystyrenesulfonate (PSS) as polyanion. While PS57PA8/PSS layer-by-layer deposition was not uniform, it was found that PB30PA8/PSS gave homogenous and stable films on hydrophilic glass substrates. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 703-712, 1998
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 68
    Digitale Medien
    Digitale Medien
    Kinetics of the photoinitiated inverse microemulsion polymerization of 2-methacryloyl oxyethyl trimethyl ammonium chloride (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 737-748 
    Details
    ISSN: 0887-624X
    Schlagwort(e): inverse microemulsion polymerization ; MADQUAT ; nucleation ; photopolymerization ; molecular weights ; flocculants ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The polymerization of inverse microemulsions of 2-methacryloyl oxyethyl trimethyl ammonium chloride stabilized by a blend of nonionic emulsifiers (a sorbitan sesquioleate and a sorbitan monooleate) and initiated by UV light in the presence of Azobis(isobutyronitrile) (AIBN) was investigated. The effect of initiator concentration, light intensity, emulsifier concentration, and dispersed phase weight fraction on the polymerization rate (Rp), number of polymer particles (Np), and polymer molecular weight (Mw) was studied. The application of this process to tubular reactors is discussed. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 737-748, 1998
    Zusätzliches Material: 15 Ill.
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  • 69
    Digitale Medien
    Digitale Medien
    Molecular weight distribution of crosslinked polymers produced in emulsion (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1127-1156 
    Details
    ISSN: 0887-624X
    Schlagwort(e): emulsion polymerization ; crosslinking and long-chain branching ; molecular weight distribution ; compartmentalization ; gel formation ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A kinetic model for evaluating the chain length distribution of a branched polymer produced in emulsion was developed. Chain branching occurring through any intermolecular mechanism is considered, namely, crosslinking, chain transfer to polymer and propagation to terminal double bond. The model accounts for active chain compartmentalization and, when coupled to a model able to describe the evolution of the polymerization system, allows evaluation of the cumulative properties of the produced polymer both in the pregel and postgel phases. The numerical difficulties related to the description of a rather wide polymer chain population and of gel formation are overcome by using the ‘numerical fractionation’ technique. A parametric analysis of both instantaneous and cumulative properties is reported and discussed, with special attention to the role of radical compartmentalization in determining the molecular weight properties of a polymer produced in emulsion. Significant differences with the molecular weights computed using models developed for homogeneous (non compartmentalized) systems have been found. A comparison with the predictions of Flory's statistical theory is also reported in terms of gel point and gel weight fraction. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1127-1156, 1998
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
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  • 70
    Digitale Medien
    Digitale Medien
    Cationic copolymerization of cyclic ketene acetals: The effect of substituents on reactivity (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 861-871 
    Details
    ISSN: 0887-624X
    Schlagwort(e): 2-methylene-1,3-dioxane ; 4-methyl-2-methylene-1,3-dioxane ; 4,4,6-trimethyl-2-methylene-1,3-dioxane ; 2-methylene-1,3-dioxolane ; 4-methyl-2-methylene-1,3-dioxolane ; 4,5-dimethyl-2-methylene-1,3-dioxolane ; cationic copolymerization ; reactivity ratio ; relative reactivity ; ring-retained polymerization ; cyclic ketene acetals ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Cationic copolymerizations of 4-methyl-2-methylene-1,3-dioxane, 2 (M1), with 2-methylene-1,3-dioxane, 1 (M2); of 4,4,6-trimethyl-2-methylene-1,3-dioxane, 3 (M1), with 2-methylene-1,3-dioxane, 1 (M2); of 4-methyl-2-methylene-1,3-dioxolane, 5 (M1), with 2-methylene-1,3-dioxolane, 4 (M2); and of 4,5-dimethyl-2-methylene-1,3-dioxolane, 6 (M1), with 2-methylene-1,3-dioxolane, 4 (M2) were conducted. The reactivity ratios for these four types of copolymerizations were r1 = 1.73 and r2 = 0.846; r1 = 2.26 and r2 = 0.310; r1 = 1.28 and r2 = 0.825; r1 = 2.23 and r2 = 0.515, respectively. The relative reactivities of these monomers towards cationic polymerization are: 3 〉 2 〉 1; and 6 〉 5 〉 4. With both five- and six-membered ring cyclic ketene acetals, the reactivity increased with increasing methyl substitution on the ring. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 861-871, 1998
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 71
    Digitale Medien
    Digitale Medien
    Enzymatic activity of trypsin adsorbed on temperature-sensitive composite polymer particles (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 883-888 
    Details
    ISSN: 0887-624X
    Schlagwort(e): temperature sensitive ; particle ; emulsion polymerization ; morphology ; adsorption ; enzyme ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Two kinds of temperature-sensitive composite polymer particles were prepared by seeded emulsion copolymerizations of (dimethylamino)ethyl methacrylate and ethylene glycol dimethacrylate with 0.14 μm-sized polystyrene and 0.26 μm-sized poly(methylmethacrylate) seed particles. To evaluate the usefulness as a carrier for biomolecules, the enzymatic activities of trypsin adsorbed on these two composite polymer particles were measured at temperatures above and below each lower critical solution temperature (LCST). In both cases, adsorbed trypsin retained its enzymatic activity during repeated adsorption/desorption measurements. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 883-888, 1998
    Zusätzliches Material: 7 Ill.
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  • 72
    Digitale Medien
    Digitale Medien
    Synthesis of (1→6)-2,5-anhydro-D-glucitol through cyclopolymerization of 3,4-di-O-allyl-1,2 : 5,6-dianhydro-D-mannitol and optical resolution ability of its derivative in HPLC (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 901-909 
    Details
    ISSN: 0887-624X
    Schlagwort(e): (1→6)-2,5-anhydro-D-glucitol ; HPLC ; optical resolution ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The cyclopolymerization of 3,4-di-O-allyl-1,2 : 5,6-dianhydro-D-mannitol (1) was carried out using BF3·OEt2 and t-BuOK. The polymer obtained by the polymerization with BF3·OEt2 mainly consisted of (1→6)-bonded 3,4-di-O-allyl-2,5-anhydro-D-glucitol as the five-membered constitutional repeating unit, though it contained a small amount of other cyclic repeating units. On the other hand, during the polymerization using t-BuOK, the stereoregular polymer (1→6)-linked 3,4-di-O-allyl-2,5-anhydro-D-glucitol (2) was synthesized via a regio- and stereoselective mechanism. Cleavage of the allyl ether linkage in polymer 2 occurred to produce the polymer consisting of only 2,5-anhydro-D-glucitol units, i.e., (1→6)-2,5-anhydro-D-glucitol (3). Chromatographic enantioseparation of chloroquine and tröger base has been performed on (3,5-dimethylphenyl)carbamate and 4-methylbenzoate derivatives of 3 as a chiral stationary phase for high-performance liquid chromatography. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 901-909, 1998
    Zusätzliches Material: 4 Ill.
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  • 73
    Digitale Medien
    Digitale Medien
    Model structures of thermoplastic polyesters having regularly alternated aromatic and fluorinated segments (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 939-947 
    Details
    ISSN: 0887-624X
    Schlagwort(e): fluorine ; perfluoropolyether ; polyester ; segmented ; thermoplastic ; interfacial synthesis ; thermal transitions ; dynamic-mechanical properties ; chemical resistance ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Linear segmented polyesters containing soft perfluoropolyether (PFPE) and hard aromatic segments are obtained by an interfacial polycondensation reaction of an acyl chloride-ended fluorinated prepolymer with various aromatic diphenols in the presence of phase transfer catalysts (PTC) as accelerators. Experimental conditions for reaching high molecular weights are discussed. The calorimetric analysis (DSC) of all the polyesters synthesized shows a typical biphasic morphology, where a very low Tg (〈 -110°C) corresponding to the segregated PFPE moiety, is always accompanied by another Tg or a higher melting temperature, depending on the nature of the hard phase. Dynamic-mechanical analysis (DMA) has been carried out confirming the DSC results and suggesting diversified mechanical behaviors at the various temperatures in line with the amorphous or semicrystalline nature of the polymer. Chemical resistance was finally tested by dipping in several solvents and chemicals. The new polyesters show high contact angles, a moderate swelling in many organic solvents and excellent stability in aggressive hydrolytic environments. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 939-947, 1998
    Zusätzliches Material: 6 Ill.
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  • 74
    Digitale Medien
    Digitale Medien
    Thermosensitive lactitol-based polyether polyol (LPEP) hydrogels (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 979-984 
    Details
    ISSN: 0887-624X
    Schlagwort(e): lactitol ; hydrogel ; polyether polyol ; PEO and PPO linkage ; swelling degree ; thermosensitivity ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A series of new thermosensitive polymer hydrogels were prepared by reacting acylated poly(ethylene glycol) bis(carboxymethyl) ether (PEGBCOCl) with lactitol-based polyether polyols (LPEP). The polyether polyols were generated from propoxylation of lactitol and have molecular weights ranging from 1337 to 4055 g/mol. The hydrogels absorb water up to 1000% of their dry weight and expel free water at temperatures at and above 30°C. The wide ranging swelling behavior and excellent thermosensitivity depend closely on the degree of crosslinking and the propylene oxide lengths in the polyols. Differential scanning calorimetry of the hydrogels showed two endotherms associated with the phase transitions of PO and EO segments in the hydrogel structures. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 979-984, 1998
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 75
    Digitale Medien
    Digitale Medien
    Kinetic and microstructure studies of poly(ethylene-co-p-methylstyrene) copolymers prepared by metallocene catalysts with constrained ligand geometry (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1017-1029 
    Details
    ISSN: 0887-624X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: This paper discusses the poly(ethylene-co-p-methylstyrene) copolymers prepared by metallocene catalysts, such as Et(Ind)2ZrCl2 and [C5Me4(SiMe2NtBu)]-TiCl2, with constrained ligand geometry. The copolymerization reaction was examined by comonomer reactivity (reactivity ratio and comonomer conversion versus time), copolymer microstructure (DSC and 13C-NMR analyses) and the comparisons between p-methylstyrene and other styrene-derivatives (styrene, o-methylstyrene and m-methylstyrene). The combined experimental results clearly show that p-methylstyrene performs distinctively better than styrene and its derivatives, due to the cationic coordination mechanism and spatially opened catalytic site in metallocene catalysts with constrained ligand geometry. A broad composition range of random poly(ethylene-co-p-methylstyrene)copolymers were prepared with narrow molecular weight and composition distributions. With the increase of p-methylstyrene concentration, poly(ethylene-co-p-ethylstyrene)copolymer shows systematical decrease of melting point and crystallinity and increase of glass transition temperature. At above 10 mol % of p-methylstyrene, the crystallinity of copolymer almost completely disappears. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1017-1029, 1998
    Zusätzliches Material: 8 Ill.
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  • 76
    Digitale Medien
    Digitale Medien
    Synthesis and spinning of a thermotropic liquid crystal copolyester containing a semirigid cycloaliphatic spacer (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1473-1480 
    Details
    ISSN: 0887-624X
    Schlagwort(e): thermotropic polymers ; liquid crystalline polymers ; semirigid spacers ; melt spinning ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A thermotropic, liquid crystalline copolyester, based on 2-chlorohydroquinone, 1,4-cyclohexanedimethanol and terephthaloyl chloride, has been synthesized and melt spun. The cyclohexanedimethylene moiety acts as a semirigid spacer, introducing flexibility while preserving the thermotropic nature of the polymer. Melt-spun fibers were observed to have a high degree of molecular alignment owing to the nematic nature of the melt. Both polymer and fiber properties have been characterized. Characterization techniques used to this end include elemental analysis, hot-stage polarized light microscopy, scanning electron microscopy, dilute solution viscometry, Fourier transform infrared spectroscopy, nuclear magnetic resonance, differential scanning calorimetry, and thermogravimetric analysis. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1473-1480, 1998
    Zusätzliches Material: 9 Ill.
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  • 77
    Digitale Medien
    Digitale Medien
    Synthesis and properties of copolymers from 2-hydroxyethyl methacrylate-linked nonsteroidal antiinflammatory agents with methacrylic acid (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1481-1490 
    Details
    ISSN: 0887-624X
    Schlagwort(e): ibuprofen ; ketoprofen ; naproxen ; copolymer reactivity ; thermal stability ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Three nonsteroidal antiinflammatory drugs, 2-(4-isobutylphenyl)-propionic acid (ibuprofen), 2-(3-benzoylphenyl)-propionic acid (ketoprofen), and 2-(6-methoxy-2-naphthyl)-propionic acid (naproxen), were covalently linked with 2-hydroxyethyl methacrylate (HEMA). The drug-linked HEMA (M1) (ibuprofen-linked HEMA abbreviated as HI; ketoprofen-linked HEMA as HK, and naproxen-linked HEMA as HN), were respectively copolymerized with methacrylic acid (M2), MA, to obtain macromolecular prodrugs. The compositions of the copolymers were determined by means of a 1H-NMR spectroscopy and monomer reactivity ratios were estimated using the Kelen-Tüdös linear differential equation. The reactivity ratios are: r1 = 0.101 ± 0.012, r2 = 1.071 ± 0.065 for HI-MA; r1 = 0.344 ± 0.066, r2 = 0.966 ± 0.032 for HN-MA, and r1 = 0.650 ± 0.182, r2 = 1.032 ± 0.106 for HK-MA, respectively. The monomer reactivity toward to MA radical estimated from 1/r2 values is almost same for all three monomers (1/r2 ∼ 1). The glass transition temperatures of three drug-linked homopolymers go hand in hand with the steric hindrance of three drugs, i.e., ketoprofen 〉 naproxen ≫ ibuprofen calculated the minimum energy by computer molecular modeling. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1481-1490, 1998
    Zusätzliches Material: 8 Ill.
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  • 78
    Digitale Medien
    Digitale Medien
    Liquid chromatography of macromolecules at the critical adsorption point. II. Role of column packing: Bare silica gel (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1363-1371 
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    ISSN: 0887-624X
    Schlagwort(e): liquid chromatography ; column packing ; bare silica gel ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Liquid chromatography of macromolecules at the critical adsorption point (LC CAP) presents a potentially very powerful method for molecular characterization of complex polymers. However, LC CAP applicability is limited due to various experimental problems. The pore sizes and surface chemistry of the column packings belong to the most important weak points of the method. The LC CAP behavior of poly(methyl methacrylate)s was investigated using bare silica gels of 6, 12, and 100 nm pore sizes and with various amounts of surface silanols. Tetrahydrofuran as the adsorption suppressing liquid and toluene as the adsorption promoting liquid were mixed to form the “nearly critical” eluents. Both pore size and surface chemistry of silica were found to strongly influence the retentive characteristics of the system in the critical adsorption area. Macromolecules that were large enough to be excluded from the packing pores hardly followed the LC CAP rules: their retention volumes changed irregularly with the polymer molar mass and their recovery dropped sharply. The narrow pore silica gel-packed column governed the elution patterns of the whole column set composed of silica gels with different pore sizes. This makes the conventional LC CAP characterization of common polymers with broader molar mass distribution impractical and even not feasible. A hybrid column system was proposed containing narrow pore nonadsorptive column added in series to the meso- and macroporous LC CAP silica gels. This narrow pore column would allow separation of gas, impurities, and system peaks from the polymer peaks. The possible successive changes of the surface of silica gel, e.g., due to formation of silanols by hydrolysis or due to irreversible adsorption of some admixtures from the sample or eluent may make the LC CAP irrepeatable. Pronounced peak broadening was observed in the critical adsorption area and this effect increased strongly with the polymer molar mass. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1363-1371, 1998
    Zusätzliches Material: 7 Ill.
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  • 79
    Digitale Medien
    Digitale Medien
    New polymer syntheses. XCVII. Hyperbranched LC-polyesters based on β-(4-hydroxyphenyl)propionic acid and 4-hydroxybenzoic acid (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1397-1405 
    Details
    ISSN: 0887-624X
    Schlagwort(e): hyperbranched polyesters ; nematic phase ; phloritic acid ; vectra ; melt rheology ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Two classes of liquid crystalline hyperbranched copolyesters were prepared by the copolycondensation of silylated 3,5-bis(acetoxy)benzoic acid with mixtures of mesogenic difunctional monomers. The first class of LC-copolyesters was obtained from 1 : 1 mixtures (molar ratio) of silylated β-(4-acetoxyphenyl)propionic acid and silylated 4-acetoxybenzoic acid (poly(HPPA/HBA)). The second class of LC-copolyesters was obtained by additional copolycondensation of silylated 6-acetoxy-2-naphthoic acid. The hyperbranched copolyesters of this ternary system poly(HPPA/HBA/HNA) proved to be less crystalline in contrast to the binary system. In both classes of LC-copolyesters the degree of branching was varied via the feed ratio of 3,5-dihydroxybenzoic acid. A minimum segment length of 6 difunctional monomer units between the branching points is required to establish a nematic phase. However, a greater segment length is needed to obtain a homogeneous LC-phase. The poly(HPPA/HBA) copolyesters were also characterized by melt rheology. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1397-1405, 1998
    Zusätzliches Material: 8 Ill.
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  • 80
    Digitale Medien
    Digitale Medien
    Polymerization of acrylates by atom transfer radical polymerization. Homopolymerization of 2-hydroxyethyl acrylate (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1417-1424 
    Details
    ISSN: 0887-624X
    Schlagwort(e): 2-hydroxyethyl acrylate ; poly(2-hydroxyethyl acrylate) ; atom transfer radical polymerization (ATRP) ; controlled free radical polymerization ; MALDI-MS ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The application of atom transfer radical polymerization (ATRP) to the homopolymerization of 2-hydroxyethyl acrylate, a functional monomer, is reported. The polymerizations exhibit first-order kinetics, and molecular weights increase linearly with conversion. Polydispersities remain low throughout the polymerization (Mw/Mn ≈ 1.2). Reactions were conducted in bulk and in 1 : 1 (by volume) aqueous solution; the latter demonstrates the resilience of ATRP to protic media. Analysis of poly(2-hydroxyethyl acrylate) by MALDI-MS and 1H-NMR shows Mn,exp to be much closer to Mn,th than those observed by SEC using polystyrene standards. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1417-1424, 1998
    Zusätzliches Material: 4 Ill.
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  • 81
    Digitale Medien
    Digitale Medien
    Unbridged bivalent lanthanidocenes for isotactic and stereomultiblock polymerization of methyl methacrylate (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1599-1606 
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    ISSN: 0887-624X
    Schlagwort(e): bivalent organolanthanides ; polymerization ; methyl methacrylate ; stereomultiblock polymer ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Bivalent organolanthanides with unbridged substituted indenyl or fluorenyl ligands (1-SiMe3Ind)2YTHF (I), (9-SiMe3Flu)2YTHF (II), were found to efficiently catalyze the stereoregular polymerization of methyl methacrylate. The microstructure of resultant polymers was shown to be dependent of a conformation that the ligands adopt at the polymerization temperature. The formation of isotactic rich PMMAs from complex II was proposed to be associated with the fluctuation of the 9-trimethylsilylfluorenyls around a C2 symmetric twisted-conformation. The formation of the multi(syndioPMMA-block-iso-PMMA) polymers from the mixture of rac- and meso-isomers of I was rationalized on the basis of competing conjugate addition and inversion of the metallocene conformation. Surprisingly, both rac- and meso-isomers of I were found to operate with similar activity and stereospecifity, although the stereospecific operation of the meso-form was not completely understandable. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1599-1606, 1998
    Zusätzliches Material: 1 Ill.
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  • 82
    Digitale Medien
    Digitale Medien
    Novel hydrogen-transfer polymerization of vinyl monomer derived from p-toluenesulfonyl isocyanate and acrylamide (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1491-1494 
    Details
    ISSN: 0887-624X
    Schlagwort(e): sulfonyl isocyanate ; acrylamide ; hydrogen-transfer polymerization ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: No abstract.
    Zusätzliches Material: 1 Ill.
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  • 83
    Digitale Medien
    Digitale Medien
    p-Nitrophenol permeability and temperature characteristics of an acryloyl-L-proline methyl ester-based porous gel membrane (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1495-1500 
    Details
    ISSN: 0887-624X
    Schlagwort(e): acryloyl-L-proline methyl ester (A-ProOMe) ; methacryloyl-L-proline methyl ester (MA-ProOMe) ; porous gel membranes ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Thermoresponsive porous gel membranes were synthesized by a simultaneously occurring process consisting of radiation-induced polymerization and crosslinking in aqueous solutions at various concentrations of acryloyl-L-proline methyl ester(A-ProOMe) without a crosslinker. Permeation of p-nitrophenol (PNP) through a thermoresponsive porous gel membrane obtained at a monomer concentration of 80% (w/w) drastically reduced around 14°C, the lower critical solution temperature (LCST) of linear poly(A-ProOMe) in water, from 0.60 × 10-3 cm/min at 10°C to no permeation at 18°C, accompanied by changes in both size and shape of pores associated with gel shrinkage. Moreover, it was found that porous gel membranes with a porosity of approximately 60% had a greater PNP permeability constant through porous gel membranes with mutually connected pores obtained at a monomer concentration of 50% (w/w) than individually supported pores obtained at a monomer concentration of 70% (w/w). © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1495-1500, 1998
    Zusätzliches Material: 9 Ill.
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  • 84
    Digitale Medien
    Digitale Medien
    Polymerization under a magnetic field. VI. Triplet dye-sensitized photopolymerization of acrylamide and methyl methacrylate (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1509-1513 
    Details
    ISSN: 0887-624X
    Schlagwort(e): methylene blue ; dye-sensitized photopolymerization ; magnetic field ; triplet state ; acrylamide ; methyl methacrylate ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Methylene blue sensitized photopolymerization of acrylamide (AM) and methyl methacrylate (MMA) using triethanolamine or the sodium salt of EDTA as a reducing agent has been investigated under the influence of a magnetic field (0-7.3 kG). There was no effect of the magnetic field (MF) on the polymerization of AM and MMA in aqueous medium. However, in the water-methanol mixture (1 : 1) the yield of polymer decreases and the molecular weight increases in both cases under MF. This has been explained on the basis of the triplet mechanism. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1509-1513, 1998
    Zusätzliches Material: 5 Tab.
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  • 85
    Digitale Medien
    Digitale Medien
    Porous monodisperse poly(divinylbenzene) microspheres by precipitation polymerization (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1543-1551 
    Details
    ISSN: 0887-624X
    Schlagwort(e): polymer microspheres ; monodisperse ; crosslinked ; porosity ; porogen ; precipitation polymerization ; divinylbenzene ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The precipitation polymerization of commercial divinylbenzene in acetonitrile containing up to 40 vol. % toluene or other cosolvents is shown to produce novel porous monodisperse poly(divinylbenzene) microspheres. These microspheres have diameters between 4 and 7 μm, total pore volumes of up to 0.52 cm3/g, and surface areas of up to 800 m2/g. As no surfactant nor stabilizer was used in the preparation of these particles, their surfaces are free of any such residues. The particles were slurry-packed into stainless steel columns for size exclusion chromatography evaluation, and the results show an exclusion limit at molecular weights of 500 g/mol. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1543-1551, 1998
    Zusätzliches Material: 6 Ill.
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  • 86
    Digitale Medien
    Digitale Medien
    (Diisopropylamido) bis (methylcyclopentadienyl) lanthanides as single-component initiators for polymerization of methyl methacrylate (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1593-1597 
    Details
    ISSN: 0887-624X
    Schlagwort(e): MMA ; polymerization ; (diisopropylamido)bis(methylcyclopentadienyl)lanthanides ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: It was first found that (diisopropylamido)bis(methylcyclopentadienyl)lanthanides (MeC5H4)2LnN(i-Pr)2(THF) (Ln = Yb (1), Er (2), Y (3)) exhibit extremely high catalytic activity in the polymerization of methyl methacrylate. The reactions can be carried out over a quite broad range of polymerization temperatures from -78 to 40°C. The catalytic activity of the complexes increases with an increase of ionic radii of the metal elements, i.e. Y 〉 Er 〉 Yb. The results of GPC (gel permeation chromatography) indicate that the number-average molecular weights (Mn) of polymers obtained exceed 100 × 103 and the molecular weight distribution (Mw/Mn) becomes broad with the increase of temperature. Furthermore highly syndiotactic PMMA (87.7%) can be obtained by lowering the reaction temperature to -78°C. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1593-1597, 1998
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  • 87
    Digitale Medien
    Digitale Medien
    Preparation and properties of poly(styrene-co-maleic anhydride)/silica hybrid materials by the in situ sol-gel process (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1607-1613 
    Details
    ISSN: 0887-624X
    Schlagwort(e): sol-gel ; hybrid material ; poly(styrene-co-maleic anhydride) ; tetraethoxysilane ; (3-aminopropyl)triethoxysilane ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Poly(styrene-co-maleic anhydride)/silica hybrid material has been successfully prepared from styrene-maleic anhydride copolymer and tetraethoxysilane (TEOS) in the presence of a coupling agent (3-aminopropyl)triethoxysilane (APTES) by an in situ sol-gel process. It was observed that the gel time of sol-gel solution was dramatically influenced by the amount of APTES. The hybrid material exhibits optical transparency almost as good as both silica gel and the copolymer. The covalent bonds between organic and inorganic phases were introduced by the aminolysis reaction of the amino group with maleic anhydride units of copolymer to form a copolymer bearing trimethoxysilyl groups, which undergo hydrolytic polycondensation with TEOS. The differential scanning calorimetry (DSC) showed that the glass transition temperature of the hybrid materials increases with increasing of SiO2 composition. Photographs of scanning electron microscopy (SEM) and atomic force microscopy (AFM) inferred that the size of the inorganic particles in the hybrid materials was less than 20 nm. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1607-1613, 1998
    Zusätzliches Material: 8 Ill.
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  • 88
    Digitale Medien
    Digitale Medien
    Influence of plasma treatment on the molar mass of poly(ethylene terephthalate) investigated by different chromatographic and spectroscopic methods (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1639-1648 
    Details
    ISSN: 0887-624X
    Schlagwort(e): poly(ethylene terephthalate) (PET) ; plasma ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The influence of different types of low and atmospheric pressure plasma on poly(ethylene terephthalate) (PET) has been studied in terms of changes in molar mass and molar mass distribution. Apart from a variation of plasma gases (oxygen, helium) different types of plasma (microwave, radio frequency, corona discharge) were used for the plasma surface modification. The changes in molar mass and types of functional end groups of lower molar mass products were investigated by means of matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOFMS), whereas the high-molar mass fraction was analyzed by means of size-exclusion chromatography (SEC). The formation of crosslinked products during exposure to a helium plasma, which emits preponderately energy-rich and intense ultraviolet radiation, was proved by means of thermal field-flow fractionation (ThFFF). This method combined with a multiangle laser light scattering (MALLS) detector allows detection of weakly crosslinked polymers and microgels. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1639-1648, 1998
    Zusätzliches Material: 9 Ill.
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  • 89
    Digitale Medien
    Digitale Medien
    Synthesis and properties of poly(ether imide)s derived from 2,6-bis(3,4-dicarboxyphenoxy)naphthalene dianhydride and aromatic diamines (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1657-1665 
    Details
    ISSN: 0887-624X
    Schlagwort(e): 2,6-bis(3,4-dicarboxyphenoxy)naphthalene dianhydride ; poly(ether imide)s ; thermal behavior ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A new naphthalene unit-containing bis(ether anhydride), 2,6-bis(3,4-dicarboxyphenoxy)naphthalene dianhydride, was synthesized in three steps starting from the nucleophilic nitrodisplacement reaction of 2,6-dihydroxynaphthalene and 4-nitrophthalonitrile in N,N-dimethylformamide (DMF) solution in the presence of potassium carbonate, followed by alkaline hydrolysis of the intermediate bis(ether dinitrile) and subsequent dehydration of the resulting bis(ether diacid). High-molar-mass aromatic poly(ether imide)s were prepared using a conventional two-step polymerization process from the bis(ether anhydride) and various aromatic diamines. The intermediate poly(ether amic acid)s had inherent viscosities of 0.65-2.03 dL/g. The films of poly(ether imide)s derived from two rigid diamines, i.e. p-phenylenediamine and benzidine, crystallized during the thermal imidization process. The other poly(ether imide)s belonged to amorphous materials and could be fabricated into transparent, flexible, and tough films. These aromatic poly(ether imide) films had yield strengths of 104-131 MPa, tensile strengths of 102-153 MPa, elongation to break of 8-87%, and initial moduli of 1.6-3.2 GPa. The glass transition temperatures (Tg's) of poly(ether imide)s were recorded in the range of 220-277°C depending on the nature of the diamine moiety. All polymers were stable up to 500°C, with 10% weight loss being recorded above 550°C in both air and nitrogen atmospheres. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1657-1665, 1998
    Zusätzliches Material: 2 Ill.
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  • 90
    Digitale Medien
    Digitale Medien
    A simple method for the anionic polymerization of α-carbonyl acids in water (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1683-1683 
    Details
    ISSN: 0887-624X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 1 Ill.
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  • 91
    Digitale Medien
    Digitale Medien
    Novel aromatic polyhydrazides and poly(amide-hydrazide)s based on “multiring” flexible dicarboxylic acids (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1847-1854 
    Details
    ISSN: 0887-624X
    Schlagwort(e): polyhydrazides ; poly-1,3,4-oxadiazoles ; thermal behavior ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Two flexible dicarboxylic acid monomers, 4,4′-[isopropylidenebis(1,4-phenylene)dioxy]dibenzoic acid (1) and 4,4′-[hexafluoroisopropylidenebis(1,4-phenylene)-dioxy]dibenzoic acid (3), were synthesized from readily available compounds in two steps in high yields. High molecular-weight polyhydrazides and poly(amide-hydra-zide)s were directly prepared from dicarboxylic acids 1 and 3 with terephthalic dihydrazide (5), isophthalic dihydrazide (6), and p-aminobenzhydrazide (7) by the phosphorylation reaction by means of diphenyl phosphite (DPP) and pyridine in N-methyl-2-pyrrolidone (NMP)/LiCl, or prepared from the diacyl chlorides of 1 and 3 with the hydrazide monomers 5-7 by the low-temperature solution polycondensation in NMP/LiCl. Less favorable results were obtained when using triphenyl phosphite (TPP) instead of DPP in the direct polycondensation reactions. Except for those derived from terephthalic dihydrazide, the resulting polyhydrazides and poly(amide-hydrazide)s could be cast into colorless, flexible, and tough films with good tensile strengths. All the hydrazide polymers and copolymers are amorphous in nature and are readily soluble in various polar solvents such as NMP and dimethyl sulfoxide (DMSO). Their Tgs were recorded in the range of 162-198°C and could be thermally cyclodehydrated into the corresponding polyoxadiazoles and poly(amide-oxadiazole)s approximately in the region of 300-380°C, as evidenced by the DSC thermograms. The oxadiazole polymers and copolymers showed a dramatically decreased solubility and higher Tg when compared to their respective hydrazide prepolymers. They exhibited Tgs of 190-216°C and were stable up to 450°C in air or nitrogen. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1847-1854, 1998
    Zusätzliches Material: 4 Ill.
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  • 92
    Digitale Medien
    Digitale Medien
    Novel polyisobutylene/poly(dimethylsiloxane) bicomponent networks. I. Synthesis and characterization (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1891-1899 
    Details
    ISSN: 0887-624X
    Schlagwort(e): polyisobutylene ; poly(dimethylsiloxane) ; hydrosilation ; bicomponent networks ; molecular weight between crosslinks ; network functionality ; sol fraction ; extractables ; model networks ; end-linking ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The synthesis of novel polyisobutylene (PIB)/poly(dimethylsiloxane) (PDMS) bicomponent networks is described. The synthesis strategy (see Figure 1) was to prepare well-defined and -characterized allyl-tritelechelic polyisobutylenes [φ(PIB - C - C=C)3] and SiH-ditelechelic poly(dimethylsiloxanes) (HSi-PDMS-SiH) and then crosslink these moieties by hydrosilation. The φ(PIB - C - C=C)3 was prepared by living isobutylene polymerization followed by end-quenching with allyltrimethylsilane, whereas the HSi-PDMS-SiH was obtained by equilibrium polymerization of octamethylcyclotetrasiloxane and tetramethyldisiloxane. The detailed structures of the starting polymers were characterized by GPC and 1H-NMR spectroscopy. A series of PIB/PDMS bicomponent networks of varying compositions and average molecular weights between crosslinks (Mc) of ∼ 20,000 g/mol were assembled. Optimum crosslinking conditions were defined in terms of H2PtCl6 catalyst concentration, nature of solvent, time, temperature, and stoichiometry of ∼ CH2CH=CH2/∼SiH groups, allowing for the convenient synthesis of well-defined model bicomponent networks. Swelling studies and elemental analysis confirm the correctness of the synthetic strategy. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1891-1899, 1998
    Zusätzliches Material: 6 Ill.
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  • 93
    Digitale Medien
    Digitale Medien
    Novel polyisobutylene/poly(dimethylsiloxane) bicomponent networks. II. Network structure and property characterization (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1901-1910 
    Details
    ISSN: 0887-624X
    Schlagwort(e): polyisobutylene ; poly(dimethylsiloxane) ; bicomponent networks ; network structure ; molecular weight between crosslinks ; network properties ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The first part of this series concerned the synthesis of novel polyisobutylene (PIB)/poly(dimethylsiloxane) (PDMS) bicomponent networks; the present paper concerns the structure and property characterization of a series of bicomponent networks of varying compositions (PIB wt %/PDMS wt % = 92/8, 70/30, 50/50, 35/65) having average molecular weights between crosslinks (Mc) of ˜ 20,000 g/mol. According to network structure analysis by uniaxial equilibrium stress-strain measurements, the experimental Mc's are in excellent agreement with theoretical values. Hydrosilation end-linking efficiency was quantitated by the amount of sol and functional group analysis by 1H-NMR spectroscopy. NMR evidence indicates double-bond isomerization during hydrosilation. Network compositions by elemental analysis together with the low sol fractions indicate efficient crosslinking. These data suggest highly efficient network formation and well-defined bicomponent network structures. While PIB and PDMS showed Tg's at -72 and -124°C, respectively, the bicomponent network did not exhibit clearly discernible phase transitions. The heat stability of bicomponent networks increased slightly with increasing PDMS content showing initial (10%) degradation temperatures at ˜ 380°C in nitrogen and ˜ 320°C in air. Tensile strengths and elongations were dependent on composition and varied in the 0.6-3.8 MPa and 600-1100% ranges, respectively. The swelling behavior was not much affected by composition. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1901-1910, 1998
    Zusätzliches Material: 8 Ill.
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  • 94
    Digitale Medien
    Digitale Medien
    Copolymerization of carbon monoxide and norbornene derivatives with ester groups by palladium catalyst (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1785-1790 
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    ISSN: 0887-624X
    Schlagwort(e): carbon monoxide ; norbornene ester ; glass transition temperature ; palladium catalyst ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: In this article we will discuss the synthesis of the new copolymers of norbornene derivatives with an ester group and carbon monoxide, using Pd(CH3CN)4(BF4)2 as a catalyst and 2,2′-bipyridine as a ligand in nitromethane/methanol at 60°C. Elementary analysis, infrared spectra, and NMR spectra indicated that copolymers contain ketone, ester, and bicyclic structures. Methanol functions as the coinitiator and chain transfer agent in copolymerization. A decrease in the molar ratio of [CH3OH]/[Pd] caused an increase in molecular weight and a decrease in yield of the copolymer. The number-average molecular weight of copolymers (Mn) ranged from 3800 to 5300, and the glass transition temperature (Tg) ranged from -32 to 117°C. Thermal analysis revealed that both T10%d and Tmaxd exceeded 180 and 230°C, respectively. Linear long-chain substituents such as n-C11H23C(O)—O—CH2— drastically reduced Tg to a value of -32°C. In general, copolymers having a longer linear side-chain substituents of ester on norbornene have a more desirable solubility. Moreover, X-ray diffraction demonstrated that the degree of crystallinity decreases with an increasing length of side chain substituents. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1785-1790, 1998
    Zusätzliches Material: 2 Ill.
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  • 95
    Digitale Medien
    Digitale Medien
    LC-polyimides XXXIV. Noncrystalline thermotropic copoly(ester-imide)s based on PET (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1813-1820 
    Details
    ISSN: 0887-624X
    Schlagwort(e): poly(ester-imide)s ; poly(ethylene terephthalate) ; transesterification, nematic phase ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Four series of copoly(ester-imide)s (co-PEIs) were prepared by transesterification of poly(ethylene terephthalate), PET, with N-(4-carboxyphenyl)trimellitimide and an acetylated diphenol. Methylhydroquinone, tert. butylhydroquinone, phenylhydroquinone, and 2,7-dihydroxynaphthalene were used as diphenols. The chemical structures of these co-PEIs were characterized by chemical analyses, 1H-, and 13C-NMR spectra. A low degree of crystallinity was observed when the PET content was above 85% mol %. Between 60 and 80 mol % PET all co-PEIs are biphasic, whereas below 60 mol % the co-PEIs form a homogeneous nematic melt and below the glass transition temperature (Tg) a nematic glass. The Tgs vary continously with the molar composition but the mechanical properties drop sharply when the nematic phase changes to an isotropic one. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1813-1820, 1998
    Zusätzliches Material: 7 Ill.
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  • 96
    Digitale Medien
    Digitale Medien
    Morphology and grafting of oxazoline-functional polymer particles with various carboxylic acids (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1821-1827 
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    ISSN: 0887-624X
    Schlagwort(e): morphology ; grafting ; oxazoline-functionalized polymer particles ; carbolic acids ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Oxazoline-functionalized, crosslinked PMMA-particles, prepared by free radical nonaqueous dispersion polymerization, were grafted with n-decanoic acid and carboxylic acid-terminated polystyrene. Oxazoline groups, separated by an alkylspacer from the PMMA backbone, showed enhanced mobility with respect to the backbone, as evaluated by solid-state NMR spectroscopy using a dipolar filter. As a function of molecular mass of the carboxylic acid, the oxazoline conversion varied from 70 mol % for n-decanoic acid to 1% for monocarboxylate-terminated polystyrene CT-PS with Mn: 15,900 g/mol. Morphological studies, performed by TEM, showed that reaction with acid terminated polystyrene results exclusively in interfacial grafting at the particle surface. At low grafting levels a raspberry-like morphology was obtained, whereas grafting levels exceeding 14 wt % CT-PS resulted in core-shell morphology. Core-shell morphology was also verified by static light scattering using toluene solvent, which is isorefractive to the PMMA core. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1821-1827, 1998
    Zusätzliches Material: 6 Ill.
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  • 97
    Digitale Medien
    Digitale Medien
    Aminolysis kinetics of model and polymer-bound anhydride moieties in low- and high-viscosity media (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1573-1582 
    Details
    ISSN: 0887-624X
    Schlagwort(e): amic acid ; secondary amine ; maleic anhydride ; melt reaction kinetics ; model compounds ; polymer-bound functional groups ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: This study examines the legitimacy of using the reaction kinetics of low molecular weight model compounds in solution to predict the chemical kinetics of polymer-bound species in a homogeneous melt. The reaction under study takes place between an aliphatic secondary amine, diisooctadecylamine (DiOA), and a 5-membered anhydride ring, saturated maleic anhydride (MA), forming an amic acid product. The MA species was present as a pendant graft on either a model compound, dodecane-g-(maleic anhydride) (dodecane-g-MA), or a polymer chain, linear low-density polyethylene-g-(maleic anhydride) (LLDPE-g-MA). Pseudo-second-order kinetics of the anhydride consumption are followed by infrared spectroscopy, either in situ in dodecane solution or by scanning frozen film samples taken from a linear low-density polyethylene melt. It was found that the LLDPE-g-MA/DiOA system reacted at a slightly slower rate than the dodecane-g-MA/DiOA system in the low-viscosity solution at 140°C. In the melt, the dodecane-g-MA/DiOA system experienced a small decrease in the overall reaction rate compared to the same reaction carried out in dodecane. However, the LLDPE-g-MA/DiOA system underwent a 65% decrease in the observed second-order rate constant on going from a solution to the melt. To explain these phenomena, the effects of diffusion, miscibility, and chain entanglements in the melt are examined here. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1573-1582, 1998
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 98
    Digitale Medien
    Digitale Medien
    New polymer syntheses. XC. A-B-A triblock copolymers with hyperbranched polyester A-blocks (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 31-38 
    Details
    ISSN: 0887-624X
    Schlagwort(e): triblock copolymers ; polycondensations ; telechelic character ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Telechelic oligo(ether-ketone)s containing two trimethylsiloxy end groups and one methyl group per repeating unit were prepared by polycondensation of 4-fluoro-2′-methyl-4′-(trimethylsiloxy)benzophenone. The telechelic character was achieved by cocondensation of a small amount of silylated bisphenol-P. The end groups of the silylated oligo(ether-ketone)s were acetylated by means of acetyl chloride. On the basis of 1H-NMR end group analyses two samples of α,ω-bis(acetoxy) oligo(ether-ketone)s with DP = 14 and DP ∼ 28 were obtained. These oligo(ether-ketone)s and a 70 or 140 fold molar amount of silylated 3,5-bis(acetoxy)benzoic acid were polycondensed at 270°C in bulk. The resulting A-B-A triblock copolymers were fractionated by dissolution in tetrahydrofuran. In three out of four experiments a small fraction of precipitated material rich in oligo(ether-ketone) was isolated. The purified triblock copolymers were characterized by inherent viscosities and NMR spectra. For those samples containing the long oligo(ether-ketone) block a low degree of crystallinity was observed after annealing. Four additional polycondensations were conducted with an initial reaction temperature of 290°C. In this way a completely soluble and amorphous triblock copolymer was obtained. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 31-38, 1998
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 99
    Digitale Medien
    Digitale Medien
    Liquid crystalline epoxy resins by polyaddition of diglycidyl ether of 4,4′-dihydroxybiphenyl and difunctional aromatic compounds (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 21-29 
    Details
    ISSN: 0887-624X
    Schlagwort(e): liquid crystalline polymers ; epoxy resins ; thermotropic ; polymer chain extension ; catalytic polyaddition ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: This work is a continuation of the authors' earlier investigations of liquid crystalline epoxy resins prepared from diglycidyl ether of 4,4′-dihydroxybiphenyl (DGE-DHBP), which was used as a mesogenic agent, and aliphatic dicarboxylic compounds, which were used as flexible spacers. In this paper, the synthesis and characterization of liquid crystalline epoxy resins, prepared from DGE-DHBP and difunctional aromatic compounds are described. Three series of liquid crystalline epoxy resins were prepared by chain extension of DGE-DHBP with isomeric hydroxybenzoic and benzenedicarboxylic acids as well as diphenols. An isophthalic-terminated polyether was applied to decrease the temperature of phase transitions. The syntheses were carried out by catalytic polyaddition in the melt. Triphenylphosphine was applied as the catalyst. The resulting epoxy resins were investigated by DSC, polarizing microscope as well as by X-ray and IR spectroscopy. The phase transition temperatures and the type of mesophase of the resulting products depend on the character of the functional groups in the chain extender and on the position of the functional groups in the aromatic ring. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 21-29, 1998
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 100
    Digitale Medien
    Digitale Medien
    Preparation and properties of new soluble aromatic polyimides from 2,2′-bis(3,4-dicarboxyphenoxy)biphenyl dianhydride and aromatic diamines (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2021-2027 
    Details
    ISSN: 0887-624X
    Schlagwort(e): 2,2′-bis(3,4-dicarboxyphenoxy)biphenyl dianhydride ; aromatic polyimides ; solubility ; thermal behavior ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A new aromatic tetracarboxylic dianhydride having a crank and twisted noncoplannar structure, 2,2′-bis(3,4-dicarboxyphenoxy)biphenyl dianhydride, was synthesized by the reaction of 4-nitrophthalonitrile with biphenyl-2,2′-diol, followed by hydrolysis and cyclodehydration. The biphenyl-2,2′-diyl-containing aromatic polyimides having inherent viscosities up to 0.66 dL/g were obtained by the conventional two-step procedure starting from the dianhydride monomer and various aromatic diamines. Most of the polyimides were readily soluble in amide-type solvents such as N,N-dimethylacetamide and N-methyl-2-pyrrolidone. The aromatic polyimides had glass transition temperatures in the range of 205-242°C, and began to lose weight around 415°C, with 10% weight loss being recorded at about 500°C in air. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2021-2027, 1998
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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