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  • 1995-1999  (6,591)
  • 1985-1989  (7,557)
  • Organic Chemistry  (6,182)
  • Chemical Engineering  (5,177)
  • Theoretical, Physical and Computational Chemistry  (1,576)
  • Genetics  (1,213)
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  • 1
    Electronic Resource
    Electronic Resource
    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
    Keywords: Key words Mitochondrial DNA ; Genetics ; Maternally inherited diabetes mellitus ; Deafness ; np 3243 mutation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s005920050161
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  • 2
    Electronic Resource
    Electronic Resource
    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
    Keywords: Key words Simple sequence repeat (SSR) ; Microsatellites ; Molecular markers ; Genetics ; Fingerprinting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220051209
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  • 3
    Electronic Resource
    Electronic Resource
    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
    Keywords: Schlüsselwörter Rhadomyosarkom ; Klassifizierung ; Immunhistochemie ; Genetik ; Prognose ; Key words Rhabdomyosarcoma ; Classification ; Immunohistochemistry ; Genetics ; Prognosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: 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.
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002920050326
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  • 4
    Electronic Resource
    Electronic Resource
    Etiology of the inflammatory bowel diseases (1999)
    Springer
    International journal of colorectal disease 14 (1999), S. 2-9 
    Details
    ISSN: 1432-1262
    Keywords: Key words Inflammatory bowel disease ; Crohn's disease ; Ulcerative colitis ; Epidemiology ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003840050175
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  • 5
    Electronic Resource
    Electronic Resource
    Genetik schizophrener Störungen Neuere Konzepte und Befunde (1999)
    Springer
    Der Nervenarzt 70 (1999), S. 955-969 
    Details
    ISSN: 1433-0407
    Keywords: Schlüsselwörter Schizophrenie ; Genetik ; Schizophrenes Spektrum ; Kopplungsuntersuchungen ; Assoziationsuntersuchungen ; Key words Schizophrenia ; Genetics ; Schizophrenia spectrum ; Linkage studies ; Association studies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: 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.
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001150050524
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  • 6
    Electronic Resource
    Electronic Resource
    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
    Keywords: Key words Frontotemporal dementia ; Genetics ; Progressive supranuclear palsy ; Tauopathy ; Exon ; amplifcation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010051052
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  • 7
    Electronic Resource
    Electronic Resource
    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
    Keywords: Tax ; HTLV-1 ; Trans-activation ; Phosphorylation ; Mutagenesis ; Transcription ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02255904
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  • 8
    Electronic Resource
    Electronic Resource
    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
    Keywords: Key words Cytokinesis ; Kinase ; Mitosis ; Schizosaccharomyces pombe ; Cell division ; Phosphatase ; Mutant ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002940050455
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  • 9
    Electronic Resource
    Electronic Resource
    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
    Keywords: Key words Congenital heart disease ; Pulmonary atresia and ventricular septal defect ; Genetics ; Monosomy 22q11.2
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004310051077
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  • 10
    Electronic Resource
    Electronic Resource
    Linkage analysis of candidate myelin genes in familial multiple sclerosis (1999)
    Springer
    Neurogenetics 2 (1999), S. 155-162 
    Details
    ISSN: 1364-6753
    Keywords: Key words Multiple sclerosis ; Genetics ; Myelin basic protein ; Myelin oligodendrocyte glycoprotein ; Proteolipid protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100480050076
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  • 11
    Electronic Resource
    Electronic Resource
    Management of mantle cell lymphoma (1999)
    Springer
    Annals of hematology 78 (1999), S. 485-494 
    Details
    ISSN: 1432-0584
    Keywords: Key words Mantle cell lymphoma ; Classification ; Pathology ; Prognosis ; Immunology ; Genetics ; Antineoplastic agents ; Combined ; Therapeutic use ; Radiotherapy ; Hematopoietic stem cell transplantation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002770050545
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  • 12
    Electronic Resource
    Electronic Resource
    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
    Keywords: Key words Acute leukemia ; Genetics ; Sex ; ABO Blood group
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002770050507
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  • 13
    Electronic Resource
    Electronic Resource
    The neurofibromatoses. An overview (1999)
    Springer
    Italian journal of neurological sciences 20 (1999), S. 89-108 
    Details
    ISSN: 1126-5442
    Keywords: Key words Neurofibromatosis ; Nf1 ; Nf2 ; Mosaic/segmental neurofibromatosis ; Variants ; Classification ; Neurological manifestations ; Genetics ; Childhood ; Adulthood
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100720050017
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  • 14
    Electronic Resource
    Electronic Resource
    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
    Keywords: Key words Diabetes ; Genetics ; Phosphofructokinase ; Glycogenosis ; NIDDM ; PFK
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001090050311
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  • 15
    Electronic Resource
    Electronic Resource
    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
    Keywords: Key words Amyotrophic lateral sclerosis ; Genetics ; Glutamate transporter gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004150050532
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  • 16
    Electronic Resource
    Electronic Resource
    Early diagnosis and the clinical genetics of Alzheimer’s disease (1999)
    Springer
    Journal of neurology 246 (1999), S. 69-72 
    Details
    ISSN: 1432-1459
    Keywords: Key words Alzheimer’s disease ; Genetics ; Genetic counseling ; Predictive testing ; Diagnosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004150050310
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  • 17
    Electronic Resource
    Electronic Resource
    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
    Keywords: Key words Passiflora ; Self-incompatibility ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220051105
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  • 18
    Electronic Resource
    Electronic Resource
    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
    Keywords: Key words Almond ; Compatibility ; Genetics ; Prunus dulcis ; Ribonucleases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: 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 .
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220051299
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  • 19
    Electronic Resource
    Electronic Resource
    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
    Keywords: Key words Craniosynostosis ; Genetics ; FGFR ; Msx2 ; Development ; Skull
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003810050457
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  • 20
    Electronic Resource
    Electronic Resource
    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
    Keywords: Key words Honeybee ; Apis mellifera ; Division of labor ; Genetics ; Pollen foraging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002650050607
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  • 21
    Electronic Resource
    Electronic Resource
    Erbliche Ursachen und Risikofaktoren der Alzheimer-Krankheit (1999)
    Springer
    Der Nervenarzt 70 (1999), S. 195-205 
    Details
    ISSN: 1433-0407
    Keywords: Schlüsselwörter Alzheimer-Krankheit ; Genetik ; Risikofaktoren ; Genetische Beratung ; Key words Alzheimer’s disease ; Genetics ; Risk factors ; Genetic counseling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: 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.
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001150050423
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  • 22
    Electronic Resource
    Electronic Resource
    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
    Keywords: Key words BB rat ; Diabetes ; Genetics ; Crossing study
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s005920050114
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  • 23
    Electronic Resource
    Electronic Resource
    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
    Keywords: Key words Non-insulin-dependent diabetes mellitus ; MODY ; Hepatocyte nuclear factor-1α ; Genetics ; Microsatellite polymorphism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s005920050120
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  • 24
    Electronic Resource
    Electronic Resource
    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
    Keywords: Key words Honey bee ; Behavior ; Genetics ; Neurobiology ; Foraging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003590050196
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  • 25
    Electronic Resource
    Electronic Resource
    Genetics of psoriasis (1998)
    Springer
    Archives of dermatological research 290 (1998), S. 463-476 
    Details
    ISSN: 1432-069X
    Keywords: Key words Psoriasis ; Genetics ; HLA ; Linkage ; Epidemiology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004030050338
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  • 26
    Electronic Resource
    Electronic Resource
    Recent advances in genetic research on schizophrenia (1998)
    Springer
    Journal of biomedical science 5 (1998), S. 28-30 
    Details
    ISSN: 1423-0127
    Keywords: Genetics ; Schizophrenia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02253353
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  • 27
    Electronic Resource
    Electronic Resource
    Prediction of febrile seizures in siblings: a practical approach (1998)
    Springer
    European journal of pediatrics 157 (1998), S. 340-344 
    Details
    ISSN: 1432-1076
    Keywords: Key words Febrile seizures ; Genetics ; Family ; Risk factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004310050824
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  • 28
    Electronic Resource
    Electronic Resource
    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
    Keywords: Key words Alzheimer disease ; Risk factors ; Parental age ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100480050041
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  • 29
    Electronic Resource
    Electronic Resource
    Recent progress in the genetics of human epilepsies (1998)
    Springer
    Neurogenetics 1 (1998), S. 153-163 
    Details
    ISSN: 1364-6753
    Keywords: Key words Epilepsy ; Genetics ; Linkage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100480050024
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  • 30
    Electronic Resource
    Electronic Resource
    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
    Keywords: Key words Simple sequence repeat (SSR) ; Microsatellites ; Molecular markers ; Genetics ; Kiwifruit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220051019
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  • 31
    Electronic Resource
    Electronic Resource
    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
    Keywords: Key words Fruit trees ; Genetics ; Almond ; Prunus amygdalus ; Breeding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220050777
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  • 32
    Electronic Resource
    Electronic Resource
    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
    Keywords: Key words Cupressus sempervirens ; Cytology ; Megasporogenesis ; Megagametogenesis ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220050801
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  • 33
    Electronic Resource
    Electronic Resource
    Patient regrets after bilateral prophylactic mastectomy (1998)
    Springer
    Annals of surgical oncology 5 (1998), S. 603-606 
    Details
    ISSN: 1534-4681
    Keywords: Breast cancer ; Genetics ; Prophylactic mastectomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02303829
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  • 34
    Electronic Resource
    Electronic Resource
    Autosomal recessive polycystic kidney disease (1998)
    Springer
    Journal of molecular medicine 76 (1998), S. 303-309 
    Details
    ISSN: 1432-1440
    Keywords: Key words Autosomal recessive polycystic kidney disease ; Linkage study ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001090050221
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    Electronic Resource
    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
    Keywords: Neural networks ; Associative memory ; Brain functions ; Disordered systems ; Genetics ; Synergetics ; Self-organization ; Vitreous state
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005071706864
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    Electronic Resource
    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
    Keywords: Genetics ; body mass index ; adolescents ; race ; sex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Psychology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021619329904
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    Electronic Resource
    Neuronal ceroid lipofuscinoses: a review (1998)
    Springer
    Neurological sciences 19 (1998), S. 271-276 
    Details
    ISSN: 1590-3478
    Keywords: Neuronal ceroid lipofuscinosis ; Clinical features ; Classification ; Diagnosis ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: 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.
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00713852
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    Unexpected rate enhancement in the intramolecular carboxylic acid-catalyzed cleavage of o-carboxybenzohydroxamic acid (1998)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 11 (1998), S. 216-222 
    Details
    ISSN: 0894-3230
    Keywords: o-carboxybenzohydroxamic acid ; phthalic anhydride ; phthalic acid ; hydrolysis ; intramolecular acid catalysis ; kinetics ; activation parameters ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Phthalic anhydride was detected spectrophotometrically in the hydrolysis of o-carboxybenzohydroxamic acid (OCBA) in CH3CN-H2O solvent containing 0.03 mol dm-3 HCl. Pseudo-first-order rate constants (k1) for hydrolysis of OCBA are almost independent of the change in CH3CN content from 10 to 80% (v/v) in mixed aqueous solvents. The rate constants k1 are more than 10-fold larger than the corresponding rate constants for hydrolysis of phthalamic acid. These observations are explained in terms of a mechanism slightly different from the mechanism for hydrolysis of phthalamic acid. The activation parameters, ΔH* and ΔS*, are not affected appreciably by an increase in CH3CN content from 10 to 80% in mixed aqueous solvents. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 4 Ill.
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  • 39
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    Electronic Resource
    Solute-solvent and solvent-solvent interactions in binary solvent mixtures. Part 7. Comparison of the enhancement of the water structure in alcohol-water mixtures measured by solvatochromic indicators (1998)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 11 (1998), S. 185-192 
    Details
    ISSN: 0894-3230
    Keywords: solute-solvent interactions ; solvent-solvent interactions ; binary solvents ; alcohol-water mixtures ; water structure ; solvatochromic indicators ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A preferential solvation model that takes into account the enhancement of the structure of water when small amounts of alcohol are added was applied to solvatochromic data for binary mixtures of water with 2-methylpropan-2-ol, propan-2-ol, ethanol and methanol. Application of the model allows the calculation of the effect of the enhancement of the water structure on solvatochromic solvent properties. It is demonstrated that the enhancement of water structure increases the solvent dipolarity/polarizability and hydrogen-bond donor acidity and decreases the solvent hydrogen-bond acceptor basicity. The effect decreases in the order 2-methylpropan-2-ol-water, propan-2-ol-water, ethanol-water and methanol-water. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 5 Ill.
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  • 40
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    Electronic Resource
    Structural dependence of heterolytic bond dissociation energy of carbon-carbon σ bonds in hydrocarbons (1998)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 11 (1998), S. 157-170 
    Details
    ISSN: 0894-3230
    Keywords: heterolytic bond dissociation energy ; carbon-carbon σ bonds ; hydrocarbons ; structural dependence ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The coordination of a resonance-stabilized hydrocarbon cation and anion yielded a series of unprecedented hydrocarbons, which are susceptible to thermal heterolytic cleavage of carbon-carbon σ bonds in polar media, generating the original ions under reversible conditions. When the component ions were sufficiently stabilized, some ion pairs were even isolated as solids, thus providing the first examples of hydrocarbon salts. The direct observation of the heterolysis by means of spectroscopy permitted reliable thermodynamic treatments of the observed degree of ionic dissociation. Correlation of the free energy of heterolysis with solvent dielectric constants and parameters of ion stabilities such as pKHA, pKR+ and redox potentials revealed the importance of the thermodynamic stabilities of ions, the degree of solvation and steric congestion in the starting molecule as major controlling factors in the heterolysis. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 16 Ill.
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  • 41
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    Correlation of the rates of solvolysis of the N,N-diphenylcarbamoylpyridinium ion (1998)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 11 (1998), S. 273-276 
    Details
    ISSN: 0894-3230
    Keywords: N,N-diphenylcarbamoylpyridinium ion ; solvolysis ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Solvolyses of the N,N-diphenylcarbamoylpyridinium ion are subject to specific and/or general base catalysis, which can be eliminated by addition of perchloric acid or increased, especially in fluoroalcohol-containing solvents, by addition of pyridine. The uncatalyzed solvolyses in aqueous methanol and aqueous ethanol involve a weakly nucleophilically assisted (l  =  0.22) heterolysis and the solvolyses in the pure alcohols are anomalously slow. © 1998 John Wiley & Sons, Ltd.
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  • 42
    Electronic Resource
    Electronic Resource
    Effects of ionic and non-ionic micelles on rate of hydroxide ion-catalyzed hydrolysis of securinine (1998)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 11 (1998), S. 209-215 
    Details
    ISSN: 0894-3230
    Keywords: securinine ; cationic micelles ; anionic micelle ; non-ionic micelle ; alkaline hydrolysis ; kinetics ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effects of micelles of cetyltrimethylammonium bromide (CTABr), tetradecyltrimethylammonium bromide (TTABr), sodium dodecyl sulfate (SDS) and polyoxyethylene 10 lauryl ether (C12E10) on the rates of alkaline hydrolysis of securinine were studied at a constant [-OH] (0.05 M). An increase in the total concentrations of CTABr, TTABr, SDS and C12E10 from 0.0 to 0.2 M causes a decrease in the observed pseudo-first-order rate constants (kobs) by factors of ca 2.5, 3, 7 and 4, respectively. The observed data are explained in terms of pseudophase and pseudophase ion-exchange (PIE) models of micelle. The binding constants, KS, of securinine with SDS, C12E10, CTABr and TTABr micelles are 32.4, 14.8, 22.1, and 9.1 M-1, respectively. The magnitudes of the second-order rate constants, kM, for the reactions in the micellar pseudophase are negligible compared with the corresponding rate constant, kW, for the reaction occurring in the aqueous pseudophase for CTABr, TTABr, SDS and C12E10. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 3 Ill.
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    Electronic Resource
    Colloidal CdS-induced photocatalytic reaction of 2-methylindole - mechanistic analysis of oxidation of indoles (1998)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 11 (1998), S. 277-282 
    Details
    ISSN: 0894-3230
    Keywords: colloidal CdS-induced photochemical reactions ; photocatalytic reactions ; photooxidation ; 2-methylindole ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 2-Methylindole (2-MI) is adsorbed on the surface of colloidal CdS particles with an adsorption intensity of 0.6 × 103 dm3 mol-1. A new emission band at 530 nm is produced by forming an exciplex between excited CdS and 2-MI and the red emission due to CdS is simultaneously quenched. The emission maxima of green bands for different indoles increase in the order indole 〈 tryptophan 〈 2-MI 〈 3-MI and are observed at 508, 520, 530 and 540 nm, respectively. The shift in emission maxima is related to the oxidation potential of these substrates. The irradiation of an aerated reaction mixture containing CdS and 2-MI with visible light induces the oxidation of adsorbed 2-MI by photogenerated holes to produce 2-methyl-3-indolinone and 2-acetamidobenzaldehyde. The latter product is formed due to oxidative C - C bond cleavage of the pyrrole ring. The reactivity of trapped holes towards the adsorbed 2-MI is evidenced by a decrease in the lifetime of the red emission of CdS in the presence of 2-MI. In this reaction the possibility of the participation of singlet oxygen is ruled out. A general mechanism of CdS-induced oxidation of indoles is discussed. © 1998 John Wiley & Sons, Ltd.
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    The Menschutkin reaction of benzyl p-toluenesulfonates with N,N-dimethylanilines. Evidence for the duality of SN1 and SN2 mechanisms (1998)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 11 (1998), S. 254-260 
    Details
    ISSN: 0894-3230
    Keywords: Menschutkin reaction ; duality of SN1, SN2 mechanisms ; benzyl tosylates ; Yukawa-Tsuno equation ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The rate data for the Menschutkin reaction between strongly activated Z-substituted benzyl p-toluenesulfonates and Y-substituted N,N-dimethylanilines in acetonitrile at 35 °C fit the equation, kobs  =  k1 + k2 [DMA], which is consistent with concurrent first- and second-order processes. The k1 and k2 values for each substrate were separated based on the above equation. The SN1 rate constant, k1, is unaffected by the nature of the nucleophile, whereas the SN2 rate constant, k2, increased with the electron-donating substituent of the N,N-dimethylaniline. The substituent effect on the k1 values is linearly correlated by the Yukawa-Tsuno equation with ρ  =  -5.2 and r  =  1.3. The unimolecular reaction can be regarded as a classical SN1 mechanism. In contrast, that on the k2 values shows an upward curvature when analyzed by the Brown σ+ treatment. These results are ascribed to the simultaneous and independent occurrence of SN1 and SN2 mechanisms in the present Menschutkin reaction. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 6 Ill.
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    Editorial (1998)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 11 (1998), S. 231-231 
    Details
    ISSN: 0894-3230
    Keywords: Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: No Abstract
    Type of Medium: Electronic Resource
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  • 46
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    Solvent effects on infrared spectroscopic and calorimetric characteristics of aliphatic ketones in binary solvent mixtures (1998)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 11 (1998), S. 283-289 
    Details
    ISSN: 0894-3230
    Keywords: calorimetry ; IR spectra ; ketones ; solvation ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Solution enthalpies of n-hexane, acetone, butan-2-one and octan-2-one in a series of tetrachloromethane-acetonitrile mixtures and the carbonyl stretching absorption frequencies in the IR spectra of these ketones were determined. It was found that over the whole range of concentrations (varying from neat tetrachloromethane up to neat acetonitrile) the solvation enthalpy of these compounds can be obtained additively from the contributions of the alkyl and carbonyl fragments. The solvent effect on the solvation enthalpy of the carbonyl group was found to be satisfactorily correlated with the corresponding IR frequency shifts of the C=O group. It was also found that the sensitivities of the carbonyl IR frequencies to the solvent composition are different for various ketones. From both IR and calorimetric data, the preferential solvation parameters were evaluated. The differences between the IR spectroscopic and calorimetric data are discussed. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 4 Ill.
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  • 47
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    Solvent effects on C=O stretching frequencies of some 1-substituted 2-pyrrolidinones (1998)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 11 (1998), S. 261-272 
    Details
    ISSN: 0894-3230
    Keywords: 1-substituted 2-pyrrolidinones ; C=O stretching frequencies ; solvent effects ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In an effort to model solute-solvent interactions, the C=O stretching frequencies of five 1-substituted 2-pyrrolidinones and four other carbonyl-containing compounds were measured for 30 common solvents. These were then correlated with four empirical parameter sets and one theoretical (computational) parameter set. While an empirical parameter set gave the best correlation equations, the theoretical parameter equations are physically and statistically significant. Solvent volume, polarizability and hydrogen bond donor acidity (capacity) terms are significant in the correlation equations. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 14 Tab.
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  • 48
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    Molecular orbital calculations on the P - S bond cleavage step in the hydroperoxidolysis of nerve agent VX (1998)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 11 (1998), S. 232-240 
    Details
    ISSN: 0894-3230
    Keywords: P - S bond cleavage ; hydroperoxidolysis ; nerve agent VX ; molecular orbital calculations ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The P - S bond cleavage process in the hydroperoxidolysis of a model system for the nerve agent VX was studied using ab initio and semiempirical molecular orbital methods. Aqueous solvation effects were included through single-point calculations using the semiempirical SM5.2PD/A continuum solvation model and geometries optimized at the HF/MIDI! level of theory. The predominant pathway for P - S bond cleavage involves pseudorotation of a low-energy trigonal bipyramidal intermediate followed by apical ligand ejection. In aqueous solution, the free energy barriers for these processes are found to be 14.3 and 4.6 kcal mol-1, respectively, with electronic energies calculated at the MP2/cc-pVDZ//HF/MIDI! level of theory. By comparison with another continuum model of solvation (PCM), it is concluded that the SM5.2PD/A model performs well even for hypervalent phosphorus species, in spite of not having included any such molecules in the model's parameterization set. © 1998 John Wiley & Sons, Ltd.
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    Conformational analysis of a 12-membered crown dithioether in the solid state and in solution (1998)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 11 (1998), S. 241-253 
    Details
    ISSN: 0894-3230
    Keywords: crown dithioether ; conformational analysis ; multicomponent equilibrium ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The solid-state molecular structure and the conformational behaviour in solution of the 12-membered crown dithioether 8-methyl-1,4-dioxa-7,10-dithiacyclododecane-5,12-dione were studied by x-ray crystallography, 1H and 13C NMR spectroscopy and molecular mechanics. The conformational rigidity of some constituent structural fragments allowed a detailed analysis of the structure and distribution of the conformers. A protocol for studies of multiconformational equilibrium was developed by means of the combined use of structure calculations and dynamic NMR measurements. © 1998 John Wiley & Sons, Ltd.
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  • 50
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    Metal-catalyzed carbenoid reactions with iodonium and sulfonium ylides (1998)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 11 (1998), S. 321-333 
    Details
    ISSN: 0894-3230
    Keywords: metal-catalyzed carbenoid reactions ; iodonium ylides ; sulfonium ylides ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Transition metal-catalyzed decomposition of phenyliodonium and diphenylsulfonium ylides was investigated with regard to application in asymmetric carbenoid reactions. Phenyliodonium ylides react in the presence of Rh(II) catalysts with the same selectivity in inter- and intramolecular cyclopropanations as the corresponding diazo compounds, and intramolecular CH insertions proceed with identical enantioselectivities. With diphenylsulfonium ethoxycarbonylmethylide the Cu(I)-catalyzed cyclopropanation of olefins affords trans/cis ratios and asymmetric inductions identical with those of diazo compounds, but with Rh(II) catalysts some small, although significant, selectivity variations occur, which are ascribed to coordination of diphenyl sulfide to one of the coordination sites of the catalyst. © 1998 John Wiley & Sons, Ltd.
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    In vivo formation of C - S bonds in biotin. An example of radical chemistry under reducing conditions (1998)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 11 (1998), S. 529-535 
    Details
    ISSN: 0894-3230
    Keywords: biotin ; in vivo C - S bond formation ; radical chemistry ; reducing conditions ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The last step in the biosynthesis of biotin involves the formation of carbon-sulfur bonds at non-activated carbons catalyzed by biotin synthase. S-Adenosylmethionine (AdoMet) and an electron source are essential for activity in cell-free systems. This important finding connects biotin synthase to a family of enzymes, namely pyruvate-formate lyase, anaerobic ribonucleotide reductase and lysine 2,3-aminomutase, which use the same cofactors. Additional experimental data led to the proposition of the following general mechanism. The carbons to be functionalized are first activated by homolytic cleavage of the C - H bonds, initiated by the deoxyadenosyl radical produced by a monoelectronic reductive cleavage of AdoMet with NADPH as electron source. The electron transfer system involves flavoproteins and very likely the [Fe - S] center of biotin synthase. NADPH and the flavoproteins can be replaced by photoreduced deazaflavin. By using a deuterated substrate, a deuterium transfer into deoxyadenosine has been observed, indicating that biotin synthase should be closely related to lysine 2,3-aminomutase, which uses AdoMet as a surrogate of vitamin B12. The source of sulfur, the nature of the immediate sulfur donor and hence the mechanism of trapping of the intermediate radicals are still unknown. © 1998 John Wiley & Sons, Ltd.
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    Chemistry of secologanin. Part 5. Graphical analysis of the acidic deglycosylation of vincoside derivatives (1998)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 11 (1998), S. 622-631 
    Details
    ISSN: 0894-3230
    Keywords: secologanin ; vincoside derivatives ; acidic deglycosylation ; graphical analysis ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Acidic hydrolysis and cyclization were studied in vincoside glycosides (‘natural’ series) and their dihydro derivatives (‘dihydro’ series) in which either one or both N atoms were free or blocked by an alkyl group. For interpretation of the results, a graph was constructed in which 25 points (actually circles) represent a maximum of 81 aglycone types and 40 arrows indicate 131 possible cyclizations. The reaction matrix of the graph was under thermodynamic control and in most cases afforded the thermodynamically most stable product aglycones. In addition to the deglycosylation, two types of cyclization were observed. In azacyclizations, the preferred nucleophilic site is N-4 over N-1, and the preferred electrophilic site is C-22 in the glycosides, C-21 over C-19 and C-17 in aglycones. In oxacyclizations, the preferred nucleophilic site is O-17 over C-18 and C-21, and the preferred electrophilic site is C-19 over C-21 and C-17 in the ‘natural’ series, C-21 over C-17 in the ‘dihydro’ series. In one case, the kinetically favoured aglycone types which had been generated in the reaction mixture were trapped in a subsequent reaction (outside the graph) before thermodynamic equilibrium was attained. With the help of graphical analysis it was possible to justify the formation of the most favourable and actually isolated products and pathways out of a large number of possibilities. © 1998 John Wiley & Sons, Ltd.
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    Reactant-solute encounters in aqueous solutions studied by kinetic methods: hydration cosphere overlap and camouflage effects (1998)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 11 (1998), S. 841-846 
    Details
    ISSN: 0894-3230
    Keywords: reactant-solute encounters ; aqueous solutions ; water ; kinetic methods ; hydration cosphere destructive overlap ; camouflage effects ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Rates of chemical reactions in aqueous solutions are often sensitive to low concentrations of added solutes such as ureas, alcohols, α-amino acids and carbohydrates. In this work, several simple chemical reactions were used to probe this sensitivity, which arises from interactions between added solute and the reacting solute. It was found that derived interaction parameters provide a novel insight into interactions between solute molecules in aqueous solution. For example, it was possible to identify two interesting effects, which are termed (i) ‘destructive overlap’ of hydration cospheres and (ii) ‘camouflage effects’ by water-solute interactions. Copyright © 1998 John Wiley & Sons, Ltd.
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    Absolute proton affinities of some substituted toluenes: the additivity rule of thumb for ipso attack (1998)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 11 (1998), S. 663-669 
    Details
    ISSN: 0894-3230
    Keywords: ipso proton affinities ; additivity ; disubstituted toluenes ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The problem of the ipso protonation of toluene and its predominantly disubstituted derivatives was considered by the MP2(fc)/6-31G**//HF/6-31G*+ZPE(HF/6-31G*) theoretical model. The substituents involved covered a wide range of different donor-acceptor capabilities. It is shown that the calculated MP2 ipso proton affinities of substituted toluenes follow mutatis mutandis the same additivity rule which was found earlier to be operative in polysubstituted benzenes, naphthalenes and biphenylenes. The additivity equation is both intuitively appealing and useful, being able to offer quantitative estimates of the proton affinity by very simple calculation. It is based on the concept of the increment, which in turn describes the influence of a single substituent on the proton affinity. Any substituent behaves as a rule as if the other were non-existent, thus giving rise to the independent substituent approximation (ISA). The performance of the additivity rule of thumb is very good, as evidenced by the average absolute deviation of 1 kcal mol-1. Larger deviations are possible, but they rarely occur, being indicative of a difference in interactions between substituents in the initial neutral base and in the final cationic conjugate acid. Finally, it follows as a corollary of the present analysis that protonation ipso to the CH3 group is never thermodynamically the most favourable site of proton attack in the benzene ring, provided that there is a single unsubstituted carbon atom within the aromatic moiety. The relevance of ipso protonation in persubstituted benzenes is briefly discussed. © 1998 John Wiley & Sons, Ltd.
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    Photoinduced electron transfer and strand cleavage in pyrenyl-DNA complexes and adducts (1998)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 11 (1998), S. 561-565 
    Details
    ISSN: 0894-3230
    Keywords: pyrenyl-DNA complexes and adducts ; photoinduced electron transfer ; strand cleavage ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The fluorescence of pyrenyl residues in complexes with the nucleic acid bases G, C and T, but not A, is strongly quenched by photoinduced electron transfer mechanisms. Site-specifically modified 11-mer oligonucleotide duplexes containing a single modified guanosyl base G* bearing a covalently attached pyrenyl residue were prepared in order to probe for photochemical damage associated with these photoinduced electron transfer reactions. When the pyrenyl residue positioned at G* is photoexcited with 355 nm light, direct strand cleavage is observed at that site with low quantum yield. Frank strand breaks are also observed up to five base pairs away from G*, suggesting that intrastrand migration of a reactive intermediate from base to base is occurring. © 1998 John Wiley & Sons, Ltd.
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    From olefin cyclopropanation to olefin metathesis through catalyst engineering: recent applications of olefin metathesis to fine organic synthesis and to polymer chemistry (1998)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 11 (1998), S. 602-609 
    Details
    ISSN: 0894-3230
    Keywords: olefin metathesis ; olefin cyclopropanation ; catalyst engineering ; fine organic synthesis ; polymer chemistry ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An overview of the recent synthetic breakthroughs brought about by the discovery of new, functional group tolerant late transition metal (Rh and Ru)-based catalysts is proposed. Whereas dirhodium(II)-based complexes promote only carbene transfer reactions to olefins (i.e. olefin cyclopropanation), a few ruthenium-based catalysts can be engineered and fine tuned so as to mediate either carbene-transfer reactions or olefin metathesis. The different outcome of the reactions can be rationalized by the capability of the metal center to coordinate or not both the carbene and the olefin. This quite simple-minded approach indicates that several available coordination sites at the metal center favors metathesis reactions to the prejudice of olefin cyclopropanation. Examples of recent applications in ring opening metathesis polymerizations and copolymerizations include the formation of postpolymers of polydienes, of carbohydrate-substituted polymers and of telechelic oligomers. Application of the same ruthenium-based catalysts in ring-closing metathesis is illustrated by the formation of crown ether analogs, of unsaturated peptides and amino acids, of β-lactams, and of different bicyclic systems.
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    Imperatives for enzymatic catalysis of isomerization of sugars and sugar phosphates (1998)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 11 (1998), S. 512-518 
    Details
    ISSN: 0894-3230
    Keywords: sugar isomerization ; sugar phosphate isomerization ; enzymatic catalysis ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The relative yields of the products of isomerization of D,L-glyceraldehyde in D2O with intramolecular transfer of a hydride ([1-1H]DHA) and with proton transfer ([1-2H]DHA) were determined by high-resolution 1H NMR analyses. A study of the catalysis of this isomerization by deuteroxide ion, buffer anions and Zn2+ established the following: (1) isomerization with proton and hydride transfer occurs at approximately equal rates in dilute solutions of sodium deuteroxide; (2) Brønsted bases catalyze isomerization with proton transfer in a bimolecular reaction; (3) Zn2+ catalyzes isomerization with hydride transfer in a bimolecular reaction; and (4) Zn2+ and acetate ion react in concert to catalyze isomerization with proton transfer in a termolecular reaction. These results show that the various pathways for isomerization with proton and hydride transfer proceed via transition states of similar energies, so that there is no strong imperative for enzymatic catalysis by any particular reaction mechanism. The relevance of these results to the mechanism of action of xylose isomerase is discussed briefly. © 1998 John Wiley & Sons, Ltd.
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    Selective arylation of exocyclic N-position of 2-pyrimidylnitrenium ion photolytically generated from tetrazolo-[1,5-a]pyrimidine in the presence of trifluoroacetic acid (1998)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 11 (1998), S. 478-484 
    Details
    ISSN: 0894-3230
    Keywords: Selective arylation ; exocyclic N-position ; 2-pyrimidylnitrenium ion ; tetrazolo[1,5a]pyrimidine ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Photo-reactions of tetrazolo[1,5-a]pyrimidine (1) with benzene (2a) and substituted benzenes (2b-f) in the presence of trifluoroacetic acid (TFA) gave 2-(2-, 3- and 4-substituted anilino)pyrimidines (3-5) together with 2-aminopyridine (6) and biphenyl (7) or diarylmethanes (8b, 8c and 8e). From the effect of heavy-atom solvent on the reactions, it is reasonable to assume that 3-5 are formed via a singlet species, but 6-8 via a triplet species. The intermediacy of 2-pyrimidylnitrenium ion is consistent with the evidence derived by the above effect, by a Hammett plot with ρ = -2.9 and by effects of solvent nucleophilicity and counter-anions. The selective exocyclic N-arylation giving 3-5 is discussed. © 1998 John Wiley & Sons, Ltd.
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    Kinetics of the hydrolysis of cyclic N-substituted sulfamides: 4-amino-2-cyclohexyl- and 4-amino-2-phenethyl-2,3-dihydro-3-oxo-1,2,5-thiadiazole 1,1-dioxides (1998)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 11 (1998), S. 489-494 
    Details
    ISSN: 0894-3230
    Keywords: Cyclic N-substituted sulfonamides ; 1,2,5-thiadiazole 1,1-dioxide derivatives ; hydrolysis ; kinetics ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The hydrolysis reactions of 4-amino-2-phenethyl- and 4-amino-2-cyclohexyl-2,3-dihydro-3-oxo-1,2,5-thiadiazole 1,1-dioxide (Ia and Ib) were investigated in the range 24-73 °C in buffered aqueous solutions. The observed rate constants (kobs) are independent of pH in the range ca 1-4 pH, but increase with increase in pH above ca 4. A linear log kobs vs pH profile with unit slope is observed from pH ca 4 up to the highest experimental pH (ca 10). The products are the corresponding new compounds: 2-amino-2-[(N-substituted-sulfamoyl)imino]acetic acid salts. The C=N bond of these compounds hydrolyses further, in a slow reaction, to the sulfamide and oxalic acid derivatives. The substrates decompose to the final products without accumulation of the acetic acid derivatives under these experimental conditions. A mechanism is proposed. Rate constants and activation parameters are given for the first reaction step. Owing to steric effects, the reaction rate is higher for the N-phenethyl-substituted derivative than for the 2-cyclohexyl-substituted derivative. © 1998 John Wiley & Sons, Ltd.
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    Rate enhancement of 1,3-dipolar cycloaddition of N-methylindole: the singular role of Grignard reagents (1998)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 11 (1998), S. 455-466 
    Details
    ISSN: 0894-3230
    Keywords: 1,3-dipolar cycloaddition ; N-methylindole ; Grignard reagents ; rate enhancement ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The reactions of 2-N-methylindolyl and 2- and 3-benzo[b]thiophenyl anions with nitrile oxides and nitrilimines were performed in order to investigate whether the use of anionic dipolarophiles modifies a classical 1,3-dipolar cycloaddition. When lithium compounds were used as bases, the heterocyclic anions invariably acted as nucleophilic species; in contrast, when a Grignard reagent was employed, the N-methylindole gave cycloaddition products with an extraordinary rate enhancement. The hypothesis that N-methylindole and ethylmagnesium bromide give an adduct much more reactive than N-methylindole itself was supported by the results of a theoretical investigation. The structure and electron distribution of the adduct were determined by ab initio calculations and compared with those of known Grignard complexes with nitrogen ligands. The performance of different basis sets was tested. The quantum theory of atoms in molecules was used to determine atomic charges and to describe the nature of bonds in terms of the properties of the electron density at the bond critical points. © 1998 John Wiley & Sons, Ltd.
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    The ring inversion of silacycloheptatriene and cycloheptatriene. Comparison of the ‘aromaticity’ of planar and boat conformers estimated by nucleus-independent chemical shift (1998)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 11 (1998), S. 475-477 
    Details
    ISSN: 0894-3230
    Keywords: cycloheptatriene ; silacycloheptatriene ; ring inversion ; aromaticity ; ab initio calculation ; nucleus-independent chemical shift ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Nucleus-independent chemical shifts (NICS) of boat and planar structure of silepins (1) and cycloheptatriene (2) were calculated at the HF/6-31+G* level for the Becke3LYP/6-31G* optimized geometries in order to investigate the correlation between the inversion barrier and aromatic nature in the boat and planar forms of 1 and 2. The NICS of unsubstituted silepin 1a indicated that there is almost no stabilization in the boat form (NICS, -0.5) and that the planar form (NICS, 3.5) is relatively destabilized in comparison with the boat form. On the other hand, the NICS of 2 showed that there is considerable homoconjugative stabilization in the boat form (NICS, -4.2) and destabilization in the planar form (NICS, 8.2). In addition to the geometrical effects resulting from angle strain, these electronic effects are considered to affect the energy barriers for ring inversion, which have been calculated to be 0.9 kcal mol-1 for 1a and 5.2 kcal mol-1 for 2. © 1998 John Wiley & Sons, Ltd.
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    Hydrogen-bonding-based thermochromic phenol-amine complexes (1998)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 11 (1998), S. 737-742 
    Details
    ISSN: 0894-3230
    Keywords: thermochromism ; proton transfer ; hydrogen bond ; phenol ; amine ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Variable-temperature UV-vis, 13C NMR and IR studies showed that proton-transferred complexes were formed between phenols and amines in apolar solvents at low temperature. Upon cooling a solution of p-nitrophenol and diisopropylamine in toluene, the colour of the solution changed from colourless to yellow. This thermochromism was ascribed to the proton transfer in the hydrogen-bonding complex. Under UV-vis conditions, butylamine and imidazole also caused similar thermochromism upon complexation with p-nitrophenol, while triethylamine, quinuclidine and pyridine did not. The thermochromic behaviour was particularly dependent on the stoichiometry of the amine and the phenol: a solution of 3,3′-dibromo-5,5′-dinitro-2,2′-biphenyldiol and diisopropylamine with a molar ratio of 1:1 showed no thermochromism, while solutions with 1:2 or higher ratios showed thermochromism, indicating that excess amine is required to obtain the proton-transferred species. These results revealed that the proton-transferred species forms in apolar solvents at low temperature if an appropriate hydrogen-bonding network between the phenol and the amine can stabilize it. © 1998 John Wiley & Sons, Ltd.
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    Double fragmentation in cation radicals. An example in the NADH analogues series (1998)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 11 (1998), S. 774-780 
    Details
    ISSN: 0894-3230
    Keywords: double fragmentation ; cation radicals ; NADH analogues ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The cation radical of 9-tert-butyl-N-methylacridan, generated electrochemically or photochemically, offers, in the presence of strong bases, a remarkable example of a double fragmentation. Whereas in acidic or weakly basic media the tert-butyl radical is cleaved with concomitant formation of the methylacridinium cation, the presence of a strong base triggers the cleavage of both the methyl group borne by the nitrogen atom and the tert-butyl group on C-9 leading to acridine, formaldehyde and the tert-butyl anion, even though methylacridinium cation is stable under these conditions. The origin of this unprecedented behavior resides in the prior deprotonation of the methyl group borne by the nitrogen atom which outruns the usual deprotonation at the 9-carbon because this is slowed by the steric hindrance due to the presence of the tert-butyl group. © 1998 John Wiley & Sons, Ltd.
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    Effect of sulfuric acid on reactions of peroxymonosulfate ion with sulfides and thiol esters (1998)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 11 (1998), S. 803-808 
    Details
    ISSN: 0894-3230
    Keywords: peroxymonosulfate ion ; oxidation ; sulfuric acid ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Peroxymonosulfate ion, HSO5-, as Oxone in aqueous H2SO4, oxidizes sulfides [MeSC6H4X(p), X = Me, H, NO2] to sulfoxides and converts aryl thiobenzoates [PhCOSC6H4X(p), X = Me, H] and thiol phosphorus(V) esters [Ph2POSPh, (EtO)2POSPh, Ph2POSEt, Ph(EtO)POSEt] into the acids and sulfonate ions. Second-order rate constants increase with increasing concentration of H2SO4 (10-53 wt%), owing to the high polarity of the medium rather than to acid catalysis. The rate increases fit the Grunwald-Winstein equation based on YOTs solvent parameters derived from rate effects on SN1 solvolyses. © 1998 John Wiley & Sons, Ltd.
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    Cation radical cycloaddition polymerization: Diels-Alder copolymerization (1998)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 11 (1998), S. 825-830 
    Details
    ISSN: 0894-3230
    Keywords: cation radical cycloaddition polymerization ; Diels-Alder copolymerization ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The Diels-Alder cycloaddition copolymerization of a bis(diene) with ionizable bis(dienophiles) via a cation radical mechanism has been accomplished using tris(4-bromophenyl)aminium hexachloroantimonate as a catalyst in dichloromethane solvent. The reactions occur at 0°C and yield Diels-Alder polymers of MW up to ca. 10,000 and a polydispersity index ca. 2. © 1998 John Wiley & Sons, Ltd.
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    Molecular imprinting technology: challenges and prospects for the future (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 195-209 
    Details
    ISSN: 0899-0042
    Keywords: molecular imprinting ; molecular recognition ; chirality ; chromatography ; catalysis ; biosensor ; immunoassay ; antibody mimic ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Molecular imprinting is a technique for the fabrication of biomimetic polymeric recognition sites or “plastic antibodies/receptors” which is attracting rapidly increasing interest. By this technology, recognition matrices can be prepared which possess high substrate selectivity and specificity. In the development of this technology, several applications have been foreseen in which imprinted materials may be exchanged for natural recognition elements. Thus, molecularly imprinted polymers have been used as antibody/receptor binding mimics in immunoassay-type analyses, as enzyme mimics in catalytic applications and as recognition matrices in biosensors. The best developed application area for imprinted materials, though, has been as stationary phases for chromatography, in general, and chiral chromatography, in particular. This review seeks to highlight some of the more intriguing advantages of the technique as well as pointing out some of the difficulties encountered. The prospects for future development will also be considered. Chirality 10:195-209, 1998. © 1998 Wiley-Liss, Inc.
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    Separation of (R)- and (S)-tert-butyl 2-tert-butyl-4-methoxy-2,5-dihydro-1,3-imidazole-1-carboxylate (building block for amino acid synthesis) by preparative high performance liquid chromatography on a polysaccharide stationary phase (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 217-222 
    Details
    ISSN: 0899-0042
    Keywords: amylose ; 3,5-dimethylphenyl-carbamate ; polysaccharide phase ; tert-butyl 2-tert-butyl-4-methoxy-2,5-dihydro-1,3-imidazole-1-carboxylate; amino acid ester synthesis ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The preparative separation of the enantiomers of the title compound, a versatile chiral building block for the synthesis of unnatural amino acid esters, by high performance liquid chromatography on a chiral stationary phase (CSP), is reported for the first time. The CSP consists of amylose-(3,5-dimethylphenyl-carbamate), which has been coated onto the surface of macroporous aminopropyl-functionalized silica gel. The effect of mobile phase composition and the amount of amylose derivative on the silica gel has been thoroughly investigated. Using 2-propanol as organic modifier in hexane as mobile phase, on a semi-preparative column (200 mm × 40 mm ID, containing 192 g of stationary phase) about 200 mg of the racemate was separated per injection. Running the equipment under automatic conditions with repetitive injection mode allowed for the separation of 30 g per day. Both enantiomers were obtained with enantiopurities 〉99.75:0.25. Chirality 10:217-222, 1998. © 1998 Wiley-Liss, Inc.
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    Species-dependent enantioselective pharmacokinetics of PNU-103017, a Pyrone HIV protease inhibitor (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 210-216 
    Details
    ISSN: 0899-0042
    Keywords: enantiospecific assay ; rat ; dog ; human ; enantiomer disposition ; HIV protease inhibitor ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: PNU-103017, 4-Cyano-N-(3-(cyclopropyl(5,6,7,8,9,10-hexahydro-4-hydroxy-2-oxo-2H-cycloocta(b) pyran-3-yl)methyl)phenyl)-benzenesulfonamide, is a selective HIV aspartyl protease inhibitor under evaluation as a potential oral treatment of Acquired Immunodeficiency Diseases. PNU-103017 is a racemic mixture of two enantiomers, designated PNU-103264 (R-) and PNU-103265 (S-). Stereoselective pharmacokinetics of the two enantiomers of PNU-103017 were observed in the dog, rat, and human after single and multiple dose administration of the racemate and were apparently species-dependent. Mean enantiomeric ratios of plasma concentrations (R-/S-) at each time point were greater than 1 in the dog, ranging from 1.22 to 3.06, but less than 1 in the rat and in the human, ranging from 0.44 to 0.80 and 0.23 to 0.73, respectively. A trend towards increased or decreased (farther from 1:1, R-/S-) enantiomeric ratio of plasma concentrations with time after each administration was also observed. The enantiomeric ratio remained unchanged after multiple dose administration in the rat, dog, and human although enzyme induction and increased plasma clearance were observed for both enantiomers. Chirality 10:210-216, 1998. © 1998 Wiley-Liss, Inc.
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    Chiral interaction and stochastic kinetics in stirred crystallization of amino acids (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 238-245 
    Details
    ISSN: 0899-0042
    Keywords: chiral selectivity ; amino acid crystallization ; molecular recognition ; stochastic kinetics ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A study of chirally selective interaction in the stirred crystallization of glutamic acid and lysine is presented. The crystallization of S-glutamic acid is influenced by the presence of S-lysine but not R-lysine. Crystal nuclei in stirred systems are produced due to secondary nucleation. Secondary nucleation is an autocatalytic process in which a crystal produces secondary nuclei due to fluid motion, and due to crystal stirrer and crystal-crystal collisions. As a result of this autocatalysis, small fluctuations in the nucleation rates are amplified and the kinetics show a marked stochastic behavior. We investigate the stochastic behavior in detail and propose a kinetic mechanism that explains both the increase and the statistical distribution of the crystallization times of S-glutamic acid due to the presence of S-Lysine. Chirality 10:238-245, 1998. © 1998 Wiley-Liss, Inc.
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    Enantiomers of thalidomide: blood distribution and the influence of serum albumin on chiral inversion and hydrolysis (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 223-228 
    Details
    ISSN: 0899-0042
    Keywords: thalidomide enantiomers ; in vitro kinetics ; blood distribution ; human serum albumin ; chiral inversion ; plasma protein binding ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The aim of this investigation was to elucidate the distribution and reactions of the enantiomers of thalidomide at their main site of biotransformation in vivo, i.e., in human blood. Plasma protein binding, erythrocyte: plasma distribution, and the kinetics of chiral inversion and degradation in buffer, plasma, and solutions of human serum albumin (HSA) were studied by means of a stereospecific HPLC assay. The enantiomers of thalidomide were not extensively bound to blood or plasma components. The geometric mean plasma protein binding was 55% and 66%, respectively, for (+)-(R)- and (-)-(S)-thalidomide. The corresponding geometric mean blood:plasma concentration ratios were 0.86 and 0.95 (at a haematocrit of 0.37) and erythrocyte:plasma distributions were 0.58 and 0.87. The rates of inversion and hydrolysis of the enantiomers increased with pH over the range 7.0-7.5. HSA, and to a lesser extent human plasma, catalysed the chiral inversion, but not the degradation, of (+)-(R)- and (-)-(S)-thalidomide. The addition of capric acid or preincubation of HSA with acetylsalicylic acid or physostigmine impaired the catalysis to varying extents. Correction for distribution in blood enhances previously observed differences between the pharmacokinetics of the enantiomers in vivo. The findings also support the notion that chiral inversion in vivo takes place mainly in the circulation and in albumin-rich extravascular spaces while hydrolysis occurs more uniformly in the body. In addition, the chiral inversion and hydrolysis of thalidomide apparently occur by several different mechanisms. Chirality 10:223-228, 1998. © 1998 Wiley-Liss, Inc.
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    Mechanistic aspects of the biogenesis of rose oxide in Pelargonium graveolens L'Héritier (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 229-237 
    Details
    ISSN: 0899-0042
    Keywords: deuterium labelling ; menthocitronellol ; citronellol ; enantioselective multidimensional gas chromatography-mass spectrometry (enantio-MDGC-MS) ; dynamic headspace analysis ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mechanistic aspects of the biogenesis of the chiral monoterpenoid rose oxide in Pelargonium graveolens L'Héritier are investigated using deuterium-labelled precursors. After administration of the precursors using the cut-stem method, the dynamic headspace extracts of the plants are analysed using multidimensional gas chromatography-mass spectrometry (enantio-MDGC-MS). It is unequivocally shown that this plant is able to convert citronellol and menthocitronellol into cis-/trans-rose oxide. Menthocitronellol is converted into rose oxide with a clearly detectable enantiodiscrimination. These facts may be explained with the presence of an oxidase, which is able to oxidize citronellol and menthocitronellol in allylic position. A photooxygenation mechanism including singlet oxygen as the oxidizing agent is rather unlikely. Chirality 10:229-237, 1998. © 1998 Wiley-Liss, Inc.
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    Chloroperoxidase-induced asymmetric sulfoxidation of some conformationally restricted sulfides (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 246-252 
    Details
    ISSN: 0899-0042
    Keywords: sulfoxides ; chloroperoxidase ; asymmetric oxidation ; enantioselective ; episulfide ; gas chromatography ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Asymmetric sulfoxidation by means of a chloroperoxidase from Caldariomyces fumago and hydrogen peroxide as the oxygen source was studied for a series of sterically well-defined substrates. The stereochemistry of the sulfoxidation was the same for all substrates studied. While 2,3-dihydrobenzo[b]thiophene (1) is an excellent substrate (giving 99.5% yield and 99% e.e. of the (R)-sulfoxide), replacement of a methylene group by either a more sterically demanding group or a heteroatom caused a substantial decrease in reactivity or in reactivity as well as enantioselectivity. A further investigation of the lowered catalytic efficiency of chloroperoxidase with these substrates has been carried out in a series of competitive reactions. Thus, benzo[1,3]oxathiole (5) acted as a competitive inhibitor of the enzyme, whereas 1-thiochroman (2) and 1-thiochroman-4-one (3) were shown to be too sterically demanding to significantly compete for the active site. For the oxidation of 2, 3, and 5, it was found that in the low CPO concentration range the chemical yield after 60 min reaction time increased almost linearly with the amount of CPO used. The products from 2 and 3 could be obtained in over 80% yield with an e.e. exceeding 96%. Chloroperoxidase was also found to be an effective catalyst in the oxidation of labile episulfides, yielding the corresponding anti-sulfoxides quantitatively and giving 12% e.e. of (1R, 2R)-sulfoxide in the oxidation of propylene sulfide. Chirality 10:246-252, 1998. © 1998 Wiley-Liss, Inc.
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    1997 Chirality Medal (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 281-281 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract.
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    Circular dichroism of axially chiral methaqualone, 3-Aryl-2-mercapto- and 3-aryl-2-alkylthio-4(3H)-quinazolinones: conformational dependence of CD and assignment of absolute configuration (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 253-261 
    Details
    ISSN: 0899-0042
    Keywords: chiroptical properties ; Cotton effect ; atropisomerism ; quantum-mechanical calculation ; AM1 ; CNDO/S ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rotational strengths calculated on the basis of quantum-mechanically obtained minimum energy geometries were used to determine the absolute configurations of axially chiral 3-aryl-4(3H)-quinazolinones from the sign of the observed Cotton effects (CEs). For the spectral data, CNDO/S calculations were used; for the geometries, ab initio (RHF/6-31G) and semiempirical (AM1) theories were used. Oscillator and rotational strengths of all excited states down to 200 nm were compared to experimental absorption and circular dichroism (CD) data. It was found that the sign of the 1Lb Cotton effects obtained for the enantiomers of methaqualone and derivatives of 3-aryl-2-alkylthio-4(3H)-quinazolinones can be correlated unambiguously with the absolute configuration. Furthermore, the sign of the Cotton effect of the π-π* transition of the thiocarbonyl chromophore of 3-aryl-2-mercapto-4(3H)-quinazolinones is suitable for a successful stereochemical correlation. Chirality 10:253-261, 1998. © 1998 Wiley-Liss, Inc.
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    Sympathomimetic enantiomers and asthma (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 262-272 
    Details
    ISSN: 0899-0042
    Keywords: airway ; beta2-agonist ; racemic ; eutomer ; distomer ; hyperreactivity ; bronchospasm ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Airways of asthma patients can become hyperresponsive to airway spasmogens following regular use of isoprenaline or β2-selective sympathomimetics. Hyperreactivity that results from acute exposure of animals to these drugs is pre-empted by vagal section (a procedure which does not influence spasmolytic efficacy of sympathomimetics), is not diminished by antagonism of β2-adrenoceptors and is not associated with loss of responsivity of β2-adrenoceptors in the airways. Since activation, modulation, or blockade of β2-adrenoceptors does not determine this form of hyperreactivity, the possibility that distomers may induce hyperreactivity must be considered. Ocular and vascular responses to distomers of sympathomimetics have long been recognised and, more recently, comparable observations have been made for the airways. Thus, reactivity of guinea-pig airways to spasmogens was increased following exposure to S-isoprenaline, S-salbutamol, or S-terbutaline and exposure to S-isoprenaline or S-salbutamol can intensify symptoms in asthmatics. Regular exposure to the racemate, especially during or following an allergic reaction, predisposes to expression of hyperreactivity, which is nullified, acutely, by the eutomer. These observations imply that biological effects of sympathomimetic distomers may contribute to morbidity and mortality in asthma patients. Chirality 10:262-272, 1998. © 1998 Wiley-Liss, Inc.
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    Immobilized vancomycin as chiral stationary phase in packed capillary liquid chromatography (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 273-280 
    Details
    ISSN: 0899-0042
    Keywords: direct chiral separation ; mobile phase composition ; NSAIDs ; retention model ; vancomycin ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Fused silica-packed capillary columns containing vancomycin immobilized by reductive amination on an aldehyde-silica were used to separate enantiomers of some non-steroidal anti-inflammatory drugs. Attempts have been made to qualitatively explain the influence of various mobile phase compositions on the enantioselective retention. The effects of mobile phase pH, buffer, and organic modifier concentrations were investigated as well as the influence of salts of hydrophobic ions added to the mobile phase to induce ion pair retention. Chirality 10:273-280, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 8 Ill.
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  • 77
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    Carbamates of cellulose bonded on silica gel: Chiral discrimination ability as HPLC chiral stationary phases (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 283-288 
    Details
    ISSN: 0899-0042
    Keywords: chiral HPLC ; cellulose carbamates ; enantiomeric resolution ; warfarin ; flurbiprofen ; lorazepam ; oxazepam ; pindolol ; tertatolol ; nicardipine ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Four cellulose mixed 10-undecenoate/carbamate derivatives, simultaneously bearing 10-undecenoyl and variously substituted phenylaminocarbonyl groups, were chemically bonded on allylsilica gel. The study of the effect of these substitutions on the performance of the resulting chiral supports, and a comparison with the recently described 10-undecenoate/3,5-dimethylphenylcarbamate derivative, are presented. In this study heptane/2-propanol or heptane/chloroform mixtures were used as mobile phases. Chirality 10:283-288, 1998. © 1998 Wiley-Liss, Inc.
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    Correlation between time reversal symmetry and chirality in certain molecular processes (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 289-293 
    Details
    ISSN: 0899-0042
    Keywords: chirality ; time reversal symmetry ; asymmetric synthesis ; enantiomerism ; isomerism ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: If a molecule is identified not only by its static spatial constructions, but also by the motions at the sub-molecular level, application of time reversal symmetry operation to a certain molecule could lead to another distinguishable from the original in the sense of sub-molecular motions, a phenomenon now defined as time reversal isomerism. Assessment of the consideration of certain enantiomers as distinguishable time reversal isomers is suggested in order to evoke a comprehensive interpretation of a likely correlation between the two types of isomerisms. The conceptual basis of a connection between absolute asymmetric synthesis under the influence of external fields and the intrinsic time reversal symmetry violation at the molecular level is also established to encourage new experimental investigations on this theme. Chirality 10:289-293, 1998. © 1998 Wiley-Liss, Inc.
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  • 79
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    Synthesis of regioselectively substituted cellulose derivatives and applications in chiral chromatography (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 294-306 
    Details
    ISSN: 0899-0042
    Keywords: cellulose ; regioselective derivatization ; chiral stationary phases ; liquid chromatography ; enantioseparation ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Various cellulose-2,3-bis-arylcarbamate-6-O-arylesters and cellulose-2,3-bis-arylester-6-O-arylcarbamates, designed to test the possible combined effects of the known tris-arylcarbamate and tris-arylester classes, were synthesized with high regioselectivity at O-C(6), and their use as CSPs in liquid chromatography for enantiomeric separations was investigated. The separations obtained with the synthesized CSPs were compared to the separations achieved on a self-packed reference column, consisting of cellulose-tris-(3,5-dimethylphenyl-carbamate) as CSP standard. Among the synthesized, regioselectively substituted cellulose derivatives, 2,3-bis-O-(3,5-dimethylphenylcarbamate)-6-O-benzoate-cellulose and 2,3-bis-O-(benzoate)-6-O-(3,5-dichlorophenylcarbamate)-cellulose gave the best CSPs for the separation of the test racemates. CSPs from regioselectively substituted cellulose derivatives seem to exhibit higher selectivities than cellulose-tris-(3,5-dimethylphenylcarbamate) for certain classes of racemic compounds. Chirality 10:294-306, 1998. © 1998 Wiley-Liss, Inc.
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  • 80
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    Enantiomeric separation of rac-indoprofen by a biocatalytic procedure (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 321-324 
    Details
    ISSN: 0899-0042
    Keywords: NSAID ; esterification ; resolution ; Candida antarctica lipase ; rac-Indoprofen ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Lipase from Candida antarctica, commercially available immobilised on acrylic resin as Novozym® 435, allows for enantioselective esterification of rac-indoprofen (±)-1, with methanol in a dioxane-toluene solvent system. A double esterification process affords methyl ester (-)-(R)-2 in 85% e.e. and enantiopure (+)-(S)-1, both in good chemical yield. Chirality 10:321-324, 1998. © 1998 Wiley-Liss, Inc.
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    Kinetics of racemization of (+)- and (-)-diethylpropion: Studies in aqueous solution, with and without the addition of cyclodextrins, in organic solvents and in human plasma (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 307-315 
    Details
    ISSN: 0899-0042
    Keywords: configurational stability ; pH ; temperature ; ionic strength ; phosphate buffer concentration ; plasma protein affinity ; native cyclodextrins ; cyclodextrin derivatives ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The configurational stability of (+)- and (-)-diethylpropion [(+)- and (-)-2-(diethyl)-1-phenyl-1-propanone or (+)- and (-)-DEP] was investigated systematically from chemical, pharmaceutical, and pharmacological aspects. The enantiomeric ratio was monitored directly with a recently developed stability-indicating enantioselective HPLC method.In aqueous solutions, the rate of racemization increased non-linearly with increasing pH and with increasing phosphate buffer concentration. The racemization rate showed a positive slope with increasing temperature and decreasing ionic strength.The racemization rates of (+)- and (-)-DEP in the presence of cyclodextrins (CDs) did not differ significantly. CDs that were added to (+)- and (-)-DEP in a molar ratio 5:1 showed the following effects after dissolution in 10 mM phosphate buffer (final pH 6.7): sulfobutyl ether-β-CD (SBE-β-CD) and methylated-β-CD (Me-β-CD) retarded racemization; whereas hydroxypropyl-β-CD (HP-β-CD), acetyl-γ-CD (Ac-γ-CD), acetyl-β-CD (Ac-β-CD), γ-CD, and β-CD showed a weak destabilising effect. In contrast to the described CDs, α-CD distinctly accelerated the rate of racemization.The configurational stability of (+)- and (-)-DEP was also studied under physiological conditions. The half-life of racemization in heparinised human plasma was for both enantiomers determined to be approximately 23-25 min.In phosphate buffer (10 mM, pH 7.4), rac-DEP showed a high, but unselective affinity towards human α1-acid glycoprotein (orosomucoid) immobilised on silica (Chiral AGP).The rate of racemization of the free base of (-)-DEP dissolved in organic solutions generally increases with the polarity of the solvating agent. Chirality 10:307-315, 1998. © 1998 Wiley-Liss, Inc.
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    Determination of the rotational barriers of atropisomeric polychlorinated biphenyls (PCBs) by a novel stopped-flow multidimensional gas chromatographic technique (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 316-320 
    Details
    ISSN: 0899-0042
    Keywords: atropisomeric polychlorinated biphenyls (PCBs) ; Chirasil-Dex ; rotational barrier ; stopped-flow multidimensional gas chromatographic technique ; on-line enantiomerization kinetics ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rotational barriers ΔG
    Additional Material: 3 Ill.
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    Discrimination in resolving systems. III: Pseudoephedrine-mandelic acid (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 325-337 
    Details
    ISSN: 0899-0042
    Keywords: diastereomeric salts ; molecular recognition ; hydrogen bonding ; thermal analysis ; crystallography ; solubility ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (+)-(1S;2S)-Pseudoephedrine and racemic mandelic acid form three distinct diastereomeric salts from solutions in 95% ethanol. The least-soluble phase, a hemihydrate, contains the (2R)-mandelate. A salt phase of intermediate solubility is the unsolvated double salt, containing both the (2R)- and the (2S)-mandelate. The most-soluble salt phase contains the (2S)-mandelate. Mandelate configuration and order of solubility (based on the heats of fusion) is inverted from that found in the same system synthesized from chiral base and acid, and then crystallized from benzene solution. The (2R)-mandelate hemihydrate (-H2O at 349.5K, mp 391K), monoclinic, P21, a = 6.788(5), b = 29.415(35), c = 9.488(10)Å, β = 108.91(8)°, Z = 4 (2 ion-pairs/asymmetric unit). Intermediate double salt (2S)- and (2R)-mandelate, mp 377.6K, anorthic, P1, a = 7.758(4), b = 9.966(5), c = 13.366(6)Å, α = 72.99(4), β = 79.98(4), γ = 70.51(4)°, Z = 1 (2 ion-pairs/asymmetric unit). The (2S)-mandelate (mp 386.2K), orthorhombic, P212121, a = 7.079(6), b = 13.443(10), c = 18.820(14)Å, Z = 4 is identical to a salt made from a combination of enantiomeric moieties from benzene solution. While differing from ephedrine mandelates in configuration at one center, solubilities of pseudoephedrine mandelates in 95% ethanol are much larger. A comparison of molecular structure (non-polar and H-bonding) regions of pseudoephedrine and ephedrine mandelates shows similarities and differences that are tentatively linked to crystal properties. This study reemphasizes the necessity for consistency in solvent use in resolution and in phase identification and comparison because the phases produced are frequently dependent upon the solvent. Chirality 10:325-337, 1998. © 1998 Wiley-Liss, Inc.
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    Manipulation of chiral resolution for isoxazoline-based IIb/IIIa receptor antagonists using various mobile phase additives in subcritical fluid chromatography (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 338-342 
    Details
    ISSN: 0899-0042
    Keywords: additive ; selectivity ; efficiency ; modifier ; subcritical fluid chromatography ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Subcritical fluid chromatography (SubFC) using a carbon dioxide-methanol mobile phase is used for the chiral resolution of IIb/IIIa receptor antagonist enantiomers. The chiral resolution of three analogs, each containing two chiral centers, is optimized using various mobile phase additives. The effects that acidic, basic, and neutral additives have on retention, efficiency, and resolution are examined. The additive that gives the best resolution was found to be dependent upon the functionality and charge of the chiral analyte. For charged analytes, additives that act as competing ions of the same charge as the chiral analyte dramatically improve efficiency and resolution. Resolution of neutral chiral analyte enantiomers is also greatly affected by the choice of mobile phase additive. Chirality 10:338-342, 1998. © 1998 Wiley-Liss, Inc.
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    Mechanism of chiral asymmetry generation by chiral autocatalysis in the preparation of chiral octahedral cobalt complex (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 343-348 
    Details
    ISSN: 0899-0042
    Keywords: chiral asymmetry generation ; chiral autocatalysis ; primary nucleation ; secondary nucleation ; chiral cobalt complex ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chiral asymmetry generation, the predominant production of one enantiomer in a non-chiral environment, could occur in the production of the chiral complex cis-[CoBr(NH3)(en)2]Br2 by the reaction of [Co(H2O)2{(OH)2Co(en)2}2](SO4)2 with ammonium bromide in an aqueous medium. The main kinetic steps in the reaction system have been determined. During the reaction, the product crystallizes at an early stage. When a very small amount of crystalline enantiomer was added to the reaction system at an early stage, the same enantiomer was produced preferentially; in addition, the enantiomeric excess of the product increased with increasing the stirring rate. Thus, it seems that each enantiomer generates chiral crystals that could self-replicate through secondary nucleation when the solution is stirred; these crystals in turn enhance the production of the same enantiomer. With a computer code that simulates such a kinetic mechanism, it is shown that enantiomeric excess observed in the experiments could be reproduced. Chirality 10:343-348, 1998. © 1998 Wiley-Liss, Inc.
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    Stereoselective renal secretion of carbenicillin in rabbits: Role of the organic anion transporter at the renal brush border membrane (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 349-357 
    Details
    ISSN: 0899-0042
    Keywords: carbenicillin ; stereoselective ; secretion ; transport ; rabbit ; membrane vesicles ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Stereoselectivity in the renal secretion of carbenicillin (CBPC) was studied in rabbits. Significant renal secretion of CBPC was observed in vivo, with the secretion of the S-epimer being greater than that of the R-epimer. Stereoselective transport of CBPC was further studied in vitro using basolateral and brush border membrane vesicles prepared from rabbit kidneys. The transport of CBPC by the organic anion transporter into the basolateral membrane vesicles (BLMV) was not stereoselective. In contrast, a distinct stereoselectivity was observed in the transport of CBPC by the organic anion transporter into the brush border membrane vesicles (BBMV), with the transport of the S-epimer being more favorable. Significant epimer-epimer interactions were also observed in the transport into BBMV. The stereoselectivity of the transport of CBPC was calculated from the kinetic parameters with consideration of epimer-epimer interactions and was similar to that observed in vivo. It was concluded that the observed stereoselectivity in the renal secretion of CBPC in vivo reflected that of transport via the organic anion transporter located at the brush border membrane. Chirality 10:349-357, 1998. © 1998 Wiley-Liss, Inc.
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    Emanuel Gil-Av honorary issue of Chirality (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 371-372 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract.
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    Determination of the enantiomeric purity of commercial Jacobsen's catalyst samples (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 362-363 
    Details
    ISSN: 0899-0042
    Keywords: Jacobsen's catalyst ; enantiomeric purity determination ; chiral HPLC ; cyclodextrin chiral stationary phases ; enantioseparation ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A HPLC method is described for the chiral analysis of the commercially available Jacobsen's catalyst. A hydroxypropyl β-cyclodextrin stationary phase was used in conjunction with a nonaqueous, polar-organic mobile phase. The method can be applied to control the enantiomeric purity of the catalyst, which is of great importance for quality control of that product. High accuracy in the determination of trace levels of the unwanted enantiomer in the presence of large amounts of the desired enantiomer is demonstrated. Chirality 10:362-363, 1998. © 1998 Wiley-Liss, Inc.
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    Enantiomeric separation of several cyclic imides on a macrocyclic antibiotic (vancomycin) chiral stationary phase under normal and reversed phase conditions (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 358-361 
    Details
    ISSN: 0899-0042
    Keywords: cyclic imides ; barbiturates ; piperidine-2,6-diones ; mephenytoin ; chiral recognition ; enantioselectivity ; vancomycin chiral stationary phase ; normal-phase mode ; reversed-phase mode ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several cyclic imidic compounds (barbiturates, piperidine-2,6-diones, and mephenytoin) are enantiomerically resolved via high-performance liquid chromatography (HPLC) on a macrocyclic antibiotic covalently bonded to a silica gel support. The Chirobiotic V chiral stationary phase (CSP) column contains the antibiotic vancomycin as the chiral selector. The results of the analysis show that the substituents at the chiral carbon position of the racemic drugs affect chiral resolution. In addition, ring size may also play a role when considering the formation of analyte-CSP inclusion complexes. Contrary to the piperidine-2,6-diones, the chromatographic parameters for the barbiturates are much the same under normal- or reversed-phase conditions. The details of these results are discussed. Chirality 10:358-361, 1998. © 1998 Wiley-Liss, Inc.
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    Emanuel Gil-Av (1916-1996): A man with a legacy (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 373-374 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract.
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  • 91
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    Separation of nicotine and nornicotine enantiomers via normal phase HPLC on derivatized cellulose chiral stationary phases (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 364-369 
    Details
    ISSN: 0899-0042
    Keywords: (±)nicotine ; (±)nornicotine ; chiral separation ; enantiomers ; normal phase HPLC ; mobile phase additive ; cellulose-based chiral stationary phase ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This paper describes the enantiorecognition of (±)nicotine and (±)nornicotine by high-performance liquid chromatography using two derivatized cellulose chiral stationary phases (CSPs) operated in the normal phase mode. It was found that different substituents linked to the cellulose backbone significantly influence the chiral selectivity of the derivatized CSP. The results showed that, in general, the tris(4-methylbenzoyl) cellulose CSP (Chiralcel OJ) surpasses tris(3,5-dimethylphenyl carbamoyl) cellulose CSP (Chiralcel OD). On the former column, the resolution (±)nicotine and (±)nornicotine enantiomers depended largely on mobile phase compositions. For the separation of the nicotine enantiomers, the addition of trifluoroacetic acid to a 95:5 hexane/alcohol mobile phase greatly improved the enantioresolution, probably due to enhanced hydrogen bonding interactions between the protonated analytes and the CSP. For (±)nornicotine separation, a reduction in the concentration of alcohol in the mobile phase was more effective than the addition of trifluoroacetic acid. Possible solute-mobile phase-stationary phase interactions are discussed to explain how different additives in the mobile phase and different substituents on the cellulose glucose units of the CSPs affect the separation of both pairs of enantiomers. Chirality 10:364-369, 1998. Published 1998 Wiley-Liss, Inc.This article is a US Government work and, as such, is in the public domain in the United States of America.
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  • 92
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    Chiral separation of enantiomers via selector/selectand hydrogen bondings (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 382-395 
    Details
    ISSN: 0899-0042
    Keywords: selector/selectand associates ; hydrogen bonding ; chiral separation ; chiral phases ; enantioselectivity ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The progress made in the development of chiral stationary phases based on hydrogen-bonding selector/selectand associates is reviewed here. The structure of the different selectand/selector systems was established through X-ray diffraction and other spectroscopic techniques. The structure of the energetically more stable diastereomeric-associate was then correlated to the chromatographic results, namely to the elution order and the enantioselectivity of each of the systems. Chirality 10:382-395, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 11 Ill.
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  • 93
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    A closer study of chiral retention mechanisms (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 375-381 
    Details
    ISSN: 0899-0042
    Keywords: retention mechanisms ; separation of enantiomers ; chiral stationary phases ; equilibrium isotherms ; bonding ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The retention mechanisms and the separation of enantiomers on the classes of chiral stationary phases which are made by bonding isolated groups on the surface of an adsorbent are discussed. It is shown that retention on these phases originates from mixed mechanisms and how the individual contributions of these two mechanisms can be separated, by determining and modeling the equilibrium isotherms. A contribution originating from interactions of the isomers with the nonselective sites (type-I) and another one due to interactions with the enantioselective sites (type-II) can be determined and their importance studied as a function of several parameters, e.g., temperature or pH. This approach is illustrated with results obtained with different pairs of enantiomers on bovine serum albumin, 4-methylcellulose tribenzoate, or cellobiohydrolase immobilized on silica. Chirality 10:375-381, 1998. © 1998 Wiley-Liss, Inc.
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  • 94
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    Electronic Resource
    Tripodal trispeptide selector as a model for establishing the importance of hydrogen-bonding in enantiomer-separation (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 396-404 
    Details
    ISSN: 0899-0042
    Keywords: chirality ; helicity ; GC-stationary phase ; conformations ; 1H-NMR-studies ; molecular mechanics calculations ; enantiomer separation ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The manner of hydrogen-bonding to peptide selectors in enantiomer separation is examined with the help of a structural model. This model relies on a C3-symmetric trispeptide selector, which is stabilized by a network of distinct intramolecular hydrogen bonds. A combination of experimental and theoretical tools enables us to identify the lowest-energy conformation of the trispeptide selector and the sites of selector-substrate interactions. Experimental tools include temperature dependent 1H-NMR studies, 1D-NOE-measurements, and titration experiments, with the theoretical tools being EFF and CFF91 molecular mechanics calculations. The structural information deduced from these investigations is shown to bear on the enantioseparation of the corresponding chiral stationary phase towards derivatized amino acids. These observations, taken together, help to rationalize the mode of enantiomer-separation by amide phases as involving predominantly C7-hydrogen bonding sites. Chirality 10:396-404, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
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  • 95
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    Electronic Resource
    The chiral code: From DNA primary structures to quaternary assemblies (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 405-414 
    Details
    ISSN: 0899-0042
    Keywords: chiral-discrimination ; homochirality ; stereospecificity ; self-assembly ; supercoiling ; cholesteric mesophase ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nucleic acids are characterized by a predominant right-handed helical configuration that derives from the chirality of the sugar moiety. Hitherto, only “local” effects of this helical asymmetry, exemplified by DNA interactions with small compounds, have been documented. The results described in this study indicate that an enhanced asymmetry is required for the manifestation of chiral effects in DNA self-assembly processes or for chiral discrimination upon interactions with peptides. Two cases in which the intrinsic DNA asymmetry is enhanced are reported: rod-like superhelical species derived from linear DNA molecules, and topologically constrained supercoiled DNA. In the first case, the superhelical grooves within the DNA rods allow for a stereospecific complexation with peptides, resulting in chiral discrimination. In the second case, it is shown that the properties of cholesteric assemblies derived from supercoiled DNA are strictly determined by the enhanced asymmetry associated with molecular supercoiling. The results allow for new reflections on the concept of molecular complementarity, and indicate that spontaneously obtained chiral DNA mesophases might have played a key role in determining terrestrial homochirality. Chirality 10:405-414, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 8 Ill.
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  • 96
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    Aspects of spontaneous separation of enantiomers in two- and three-dimensional crystals (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 415-424 
    Details
    ISSN: 0899-0042
    Keywords: chiral separation ; two- and three-dimensional crystals ; grazing incidence X-ray diffraction ; atomic force microscopy ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Spontaneous separation of enantiomers in two- and three-dimensional crystals is driven by the same thermodynamic and kinetic factors. However, amphiphilic crystalline monolayers at an interface cannot possess a center of inversion, the most common symmetry element in bulk crystals. This fact should, in principle, lead to better chances for spontaneous separation in the Langmuir or Langmuir-Blodgett monomolecular films. On the other hand, the monolayers of most amphiphiles studied to date incorporate long aliphatic chains that have an intrinsic tendency to pack in a herring-bone motif requiring glide plane symmetry, thus creating a bias towards racemate formation. Moreover, 2-D crystals supposedly have a much higher degree of molecular and therefore enantiomeric disorder compared to bulk crystals. All these factors necessitate a careful choice of molecules to guarantee enantiomeric separation in two dimensions. Unambiguous detection of spontaneous resolution in 2-D appears to require atomic resolution of molecular packing arrangement, which can in principle be obtained by grazing incidence X-ray diffraction or atomic force microscopy, whereas in bulk solids spontaneous resolution can be easily detected by various macroscopic methods. This short review provides analogies between spontaneous separation in 3-D and recent examples in 2-D, showing that spontaneous separation generally depends upon subtle differences in molecular structure. Chirality 10:415-424, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 8 Ill.
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  • 97
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    Determination of the rotational barriers of atropisomeric polychlorinated biphenyls (PCBs) by a novel stopped-flow multidimensional gas chromatographic techniqueThis article was orginally published in Chirality, Volume 10, Number 4, pages 316-320. As it is suited to the theme of this issue, this article appears again here. All citations to this article should use the original volume, issue, and page range. (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 425-429 
    Details
    ISSN: 0899-0042
    Keywords: atropisomeric polychlorinated biphenyls (PCBs) ; Chirasil-Dex ; rotational barrier ; stopped-flow multidimensional gas chromatographic technique ; on-line enantiomerization kinetics ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rotational barriers ΔG† (T) of the four atropisomeric polychlorinated biphenyls (PCBs) 2,2′,3,5′,6-pentachlorobiphenyl (PCB 95), 2,2′3,3′,4,6′-hexachlorobiphenyl (PCB 132), 2,2′,3,3′,6,6′-hexachlorobiphenyl (PCB 136), and 2,2′,3,4′,5′,6-hexachlorobiphenyl (PCB 149) were determined via on-line enantiomerization kinetics by a new stopped-flow multidimensional gas chromatographic technique (stopped-flow MDGC) employing Chirasil-Dex as chiral stationary phase for enantiomer separation. The calculated rotational barriers ΔG† (T) of the trichloro-ortho-substituted atropisomers are 184 ± 2 kJ/mol for PCB 95, 189 ± 4 kJ/mol for PCB 132, and 184 ± 1 kJ/mol for PCB 149 at 300°C. The rotational barrier ΔG† (T) of tetrachloro-ortho-substituted PCB 136 is at least (or higher than) 210 kJ/mol at 320°C. Chirality 10:425-429, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
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  • 98
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    Electronic Resource
    Chiral recognition of phthalides and lactams (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 430-433 
    Details
    ISSN: 0899-0042
    Keywords: Whelk-O 1 ; chromatography ; HPLC ; enantiodifferentiation ; heterocycles ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In concert with a larger study of the processes by which chiral stationary phase CSP 1 differentiates between enantiomers, we have investigated the chromatographic separation of the enantiomers of a series of aryl-substituted heterocycles of systematically varied structure. A mechanistic picture of how these and similar resolutions occur is emerging. The mechanistic hypothesis described herein is of predictive value. Chirality 10:430-433, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
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  • 99
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    Highly enantioselective HPLC separations using the covalently bonded macrocyclic antibiotic, ristocetin A, chiral stationary phase (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 434-483 
    Details
    ISSN: 0899-0042
    Keywords: ristocetin A ; macrocyclic antibiotic ; enantiomeric separations ; underivatized amino acids ; chiral stationary phase ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The macrocyclic glycopeptide, ristocetin A, was covalently bonded to a silica gel support and evaluated as a liquid chromatographic (LC) chiral stationary phase (CSP). Over 230 racemates were resolved in either the reversed-phase mode, the normal-phase mode, or the polar-organic mode. The retention behavior and selectivity of this CSP were examined in each mode. Optimization of separations on this column is discussed. The ristocetin A CSP appeared to be complimentary to other glycopeptide CSPs (i.e., vancomycin and teicoplanin). Column stability was excellent. The CSP was not irreversibly altered when going from one mobile phase mode to another. Chirality 10:434-483, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 10 Ill.
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  • 100
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    Determination of the enantiomers of albuterol in human and canine plasma by enantioselective high-performance liquid chromatography on a teicoplanin-based chiral stationary phase (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 484-491 
    Details
    ISSN: 0899-0042
    Keywords: salbutamol ; chiral separation ; validated assay ; fluorescence detection ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A sensitive enantioselective high-performance chromatographic (HPLC) method was developed and validated to determine low levels of (-)-R and (+)-S-albuterol in plasma. Baseline resolution was achieved by using a teicoplanin-based chiral stationary phase with a polar organic mobile phase consisting of methanol/acetonitrile/glacial acetic acid/diethylamine, 40:60:0.3:0.2, (v/v/v/v) and a flow-rate of 1.0 ml/min. Enantioselectivity (α) equaled 1.18 and resolution (Rs) equaled 1.8. By using fluorescence detection maximized at 230 and 310 nm for excitation and emission, respectively, concentrations of each enantiomer could be measured down to 125 pg/ml from a 1-ml plasma sample. Initially, the method was applied to plasma samples from a small single-dose inhalation study of racemic albuterol in a human volunteer and, later, to in vivo samples from a canine inhalation study of the single enantiomer, (-)-R-albuterol. Results from the canine study showed that no chiral inversion of (-)-R-albuterol occurs in the dog. Chirality 10:484-491, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
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