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Notes: Abstract A Danish genetic study showed increased risk of cluster headache (CH) among relatives of CH patients. We studied the families of 191 CH patients (118 males, 73 females; mean age 45.9 years) attending the Milan Headache Center. Information on 3589 relatives was collected by direct interview of the probands (n = 118) or by mailed questionnaire (n = 73). The diagnostic criteria of the IHS were used. A positive family history was found in 19% (37 of 191) of the families. A total of 32 first-degree (32 of 1036, 3.1%) and 15 second-degree (15 of 2553, 0.6%) relatives were affected. The relative risk of CH was 26.89 (95% CI, 17.57–36.21) in the first-degree relatives and 4.35 (95% CI, 2.13–5.21) in second-degree relatives. This study shows increased familial risk of cluster headache in an Italian population and confirms that cluster headache is, in some families, and inherited disorder.

Notes: Abstract Migraine carries a significant hereditary determination. Familial hemiplegic migraine (FHM) has been recently linked to mutations in the CACNA1A gene on chromosome 19. CACNA1A codes for a subunit of a neural calcium channel. Other linkage loci on chromosome 1q21-23 and 1q31 have been reported. Several linkage and association studies have been performed to determine the role of the CACNA1A gene, and of other candidate genes implicated in the metabolism of serotonin and dopamine, in the more common types of migraine. Co-morbidity of migraine with vascular events has been analysed versus genetic prothrombotic factors and mitochondrial DNA, and genes involved in the inflammatory cascade have been explored. Though no definite conclusions have emerged from these studies as yet, molecular genetics of migraine can be expected to unravel the complex aetiologies of these fascinating diseases.

Notes: Abstract Molecular genetics offers a novel approach to the understanding and management of migraine since the disorder is known to have a strong genetic component. In recent studies, polymorphisms in the genes for dopamine receptors have been evaluated. Both positive and negative association studies have been reported. In particular, these data suggest that activation of the DRD2 receptor plays a modifying role in the pathophysiology of migraine. As a result, existing data provide a molecular rationale for the documented efficacy of dopamine D2 receptor antagonists in the treatment of migraine. Therefore, at the present time, molecular genetic data provide support for the hypothesis that susceptibility to migraine may be modified, in part, by variations in dopamine DRD2 receptor function.

Notes: Abstract Pathophysiological studies have dominated migraine research for several years. However, these studies are difficult to interpret because it is difficult to decide whether the observed phenomena are primary or secondary to the migraine attack. For that reason it is important that future migraine research focus on studies that concern migrain etiology. Migraine is a paroxysmal disorder. It is most likely and ion-channel disorder like familial hemiplegic migraine. The present paper focuses on genetic factors in migraine and chronic tension-type headache.

Notes: Abstract  Von Hippel-Lindau disease (VHL) is a hereditary cancer syndrome caused by germline mutations of the VHL tumor suppressor gene. Major progress has been made in the last decade in both clinical and fundamental aspects of VHL. The VHL gene product, pVHL, has major and multiple functions: pVHL regulates not only first angiogenesis but also extracellular matrix formation and the cell cycle. A molecular diagnosis of VHL is now available, leading to a transformation in clinical management of patients and their families. Diagnosis of VHL has to be suspected in patients with a VHL-related tumor without familial history and especially in case of hemangioblastoma or endolymphatic sac tumors. Such patients should be systematically investigated for clinical and molecular evidence of VHL disease. Treatment of symptomatic hemangioblastomas remains mainly neurosurgical, often in emergency, but stereotactic radiosurgery is emerging as an alternative therapeutic procedure. In the future, antiangiogenic drugs could represent a potential medical treatment of CNS hemangioblastomas in view of their highly vascular structure. Lastly, visceral manifestations of VHL disease are also of critical importance and require early detection for effective treatment.

Notes: Abstract Migraine is a common chronic disorder with an etiology still mostly unknown. Several neurotransmitters such as dopamine and serotonin are considered to be involved in the pathogenesis of the disease and the study of their systems is crucial in the understanding of migraine. Dopaminergic receptors are variously represented in human CNS and periphery. The hypothesis that a hypersensitivity of the dopaminergic system may have a role in migraine is based on clinical and genetic data. Genetic data are represented by association studies using dopaminergic genes as candidate genes which show that the D2 receptor gene appears to be involved in the pathogenesis of migraine.

Notes: Abstract Human leukocyte Antigens (HLA) are encoded by genes located on chromosome 6p21. Genes important in migraine are being recognized in two basic ways: association studies and linkage analysis. One of the strongest associations is with the HLA region. Actually, genome scan studies suggest that multiple genes are involved in both migraine without aura (MWoA) and migraine with aura (MWA). However, both MWoA and MWA are disorders in which multiple factors, including environmental and genetic factors, confer disease susceptibility. Linkage analysis is identifying new candidate genes that will help to explain the etiology of migraine. In this review previous studies regarding genetic susceptibility to migraine are analyzed, particularly those related to the HLA region. I discuss evidence that HLA shared-hyplotypes in MWoA-affected pairs in different than that expected, that HLA-DR2 antigen provides additional basis for the proposed genetic heterogeneity between MWoA and MWA, and lastly that TNFB gene studies seem to play an important role in the susceptibility to MWoA. In the past years, major advances hae been made in understanding the genetic foundation of MWoA and MWA. Our reported genome-scan studies support the concept that MWoA/MWA are coinherited with a particular HLA region. However, the examination of candidate genes (Ca2+ channel, vascular, CNS, etc.) in a large migraine population seems to be the correct direction in which we have to move. More MWoA/MWa gene studies are needed to test this developing hypothesis and to further establish the complete genetic scenario of migraine.

Notes: ABSTRACT¶Parkinson's disease (PD) is a neurodegenerative disease with clinical features resulting from deficiency of dopamine in the nigrostriatal system. Most PD cases are sporadic and the primary cause of the disease is still unknown. Recently, familial PD and parkinsonism have received much attention because these forms of the disease might provide clues to the genetic risk factors involved in the pathogenesis of idiopathic PD. To date, two causative genes, α-synuclein and the parkin gene, have been identified. α-Synuclein is involved in the pathogenesis of an autosomal dominant form of PD and constitutes a major component of the Lewy body, which is a pathological hallmark of idiopathic PD. In addition, mutations in the parkin gene have been identified as the cause of autosomal recessive juvenile parkinsonism (AR-JP). AR-JP manifests itself as a highly selective degeneration of the substantia nigra and the locus coeruleus, but without Lewy body formation. In addition to these two genes, four chromosomal loci have been linked to other forms of familial PD. Furthermore, there are a number of other pedigrees of familial PD in which linkage to known genetic loci has been excluded. Molecular cloning of these disease genes and elucidation of the function of their gene products will greatly contribute to our understanding of the pathogenesis of idiopathic PD.

Notes: Abstract  Mechanisms underlying susceptibility to skin irritants are not clearly understood. Cytokines play a key role in inflammation, and functional polymorphisms in cytokine genes may affect responses to irritants. We investigated the relationship between polymorphism in the tumor necrosis factor (TNF) α-chain gene and responses to irritants. Volunteers (n=221) tested with sodium dodecyl sulfate (SDS) and benzalkonium chloride (BKC) were divided into responders and nonresponders and high and low irritant-threshold groups. DNA was assayed for the TNF-308 polymorphism by a polymerase chain reaction-restriction fragment length polymorphism method. There was a significant increase in the A allele (P=0.030) and AA genotype (P=0.023) in both the SDS low irritant-threshold group and in SDS responders (A allele P=0.022, AA genotype P=0.048). In the BKC low irritant-threshold group, we found a significant increase in the A allele (P=0.002) and AA genotype (P=0.016). Individuals with a low threshold to both irritants demonstrated a significant increase (P=0.002) in the A allele. This is the first description of a nonatopic genetic marker for irritant susceptibility in normal individuals. Genotyping for theTNF-308 polymorphism may thus contribute to screening of individuals deemed at risk of developing irritant contact dermatitis.

Notes: Abstract Risk of critical illness is determined both by genetic and environmental influences, particularly those relating to infectious and cardiovascular diseases. Physiologically-based scoring systems cannot measure prior risk because they do not quantify physiological reserve independently of the acute illness. Genetic profiling could be useful for risk assessment. Early detection of critical illness involves identifying physiological ’triggers' for referral; this requires the education of nursing and medical staff in their significance. Analysis of the relationship between risk factors and interventions may need complex modelling techniques. Therapeutic strategies depend on the nature of the underlying problem: the most useful are likely to be those which enhance tissue oxygen delivery and resistance to infection.

Notes: Abstract  Two newborns with glomerulocystic kidney disease manifesting as late onset oligohydramnion and neonatal anuria, yet without severe respiratory distress, are presented. They had a similar perinatal course and associated clinical manifestations. No associated congenital or inherited malformation syndrome could be defined. Both infants’ parents were first degree cousins and belonged to the same small Bedouin tribe, and neither they nor the infants’ siblings had polycystic kidneys or renal insufficiency, pointing to either a possible genetic etiology or a common external toxic exposure.

Notes: Abstract Thanks to the World Wide Web, most results of research in genetics are made available in public databases. At the present time there are resources on genetic diseases, genes and their location, mutations of already cloned genes and on laboratories performing the mutation analysis. The main resources on phenotypes are On-line Mendelian Inheritance in Man (OMIM), Pedbase, GeneClinics, London Dysmorphology Database (LDDB) and Orphanet. The main resources on human genes are, in addition to OMIM, the Genome Database, Genatlas and Genecard. There are also two major sequence databases. All of them can be queried using the OMIM number of the disease. Central databases of mutations, as well as locus specific databases have been created. Their list is maintained at the Human Genome Organisation mutation database initiative website. Several initiative have been taken to integrate all these data and help the clinician to find out quickly what he/she needs. The website of the National Center for Biotechnology Information is the best example of such an effort with sections on diseases, a genome guide, and locus links. Several databases of genetic testing resources have been established. GeneTests is an on-line genetics resource that contains a directory of North American laboratories providing testing for heritable disorders. Orphanet is a similar database on French services which is in the process of becoming a European database. Conclusion Even if clinicians do not have as many services at their disposal as the molecular geneticists, various useful databases already exist and should no longer be ignored in practice.

Notes: Abstract Over the last decade mild hyperhomocysteinaemia has widely been recognised as a new risk factor for arteriosclerosis and thrombosis. Main regulating enzymes of homocysteine (Hcy) metabolism are cystathionine β-synthase (CBS), methionine synthase and methylenetetrahydrofolate reductase (MTHFR). Early studies on patients with vascular disease described elevated Hcy concentrations after methionine loading and decreased CBS activity, resembling heterozygotes for CBS deficiency. Therefore, heterozygosity for CBS deficiency was proposed as the main cause of mild hyperhomocysteinaemia. However, more recent enzymatic and molecular genetic studies have demonstrated that heterozygosity for CBS deficiency is not or only a very minor cause of mild hyperhomocysteinaemia in vascular disease. We discovered two common genetic causes of mild hyperhomocysteinaemia, the 677C 〉 T and the 1298A 〉 C mutations in the coding region of MTHFR. The 677C 〉 T mutation causes reduced enzyme activity with thermolabile protein properties, elevated Hcy and low-normal or decreased plasma folate levels. The 1298A 〉 C mutation relates also to decreased enzyme activity, but not to thermolabile protein, and Hcy and folate levels are not influenced. However, compound heterozygosity for these two mutations, i.e. individuals with the 677CT/1298AC genotype, have elevated Hcy and decreased plasma folate levels. Gene-enviroment interactions between 677C 〉 T and folate is demonstrated in individuals with the 677TT genotype. Those with low-normal folate have elevated Hcy, whereas those with high-normal folate have normal Hcy concentrations. The elevated Hcy levels due to these mutations can be normalised by administration of folate, but whether folate reduces the risk of cardiovascular disease remains to be established. Conclusion Heterozygosity for cystathionine β-synthase deficiency is a minor cause of hyperhomocysteinaemia. The current data on mutations in the methylenetetrahydrofolate reductase gene do not tell us whether elevated plasma homocysteine plays a causal role in vascular disease. Low cellular vitamin status may be a possible cause and homocysteine may just be a marker for this situation.

Notes: Abstract The epidemic diffusion of obesity in industrialised countries has promoted research on the aetiopathogenesis of this disorder. The purpose of this review is to focus mainly on the contribution that European research has made to this field. Available evidence suggests that obesity results from multiple interactions between genes and environment. Parents obesity is the most important risk factor for childhood obesity. Twin, adoption, and family studies indicated that inheritance is able to account for 25% to 40% of inter-individual difference in adiposity. Single gene defects leading to obesity have been discovered in animals and, in some cases, confirmed in humans as congenital leptin deficiency or congenital leptin receptor deficiency. However, in most cases, genes involved in weight gain do not directly cause obesity but they increase the susceptibility to fat gain in subjects exposed to a specific environment. Both genetic and environmental factors promote a positive energy balance which cause obesity. The relative inefficiency of self-adapting energy intake to energy requirements is responsible for fat gain in predisposed individuals. The role of the environment in the development of obesity is suggested by the rapid increase of the prevalence of obesity accompanying the rapid changes in the lifestyle of the population in the second half of this century. Early experiences with food, feeding practices and family food choices affect children's nutritional habits. In particular, the parents are responsible for food availability and accessibility in the home and they affect food preferences of their children. Diet composition, in particular fat intake, influences the development of obesity. The high energy density and palatability of fatty foods as well as their less satiating properties promotes food consumption. TV viewing, an inactivity and food intake promoter, was identified as a relevant risk factor for obesity in children. Sedentarity, i.e. a low physical activity level, is accompanied by a low fat oxidation rate in muscle and a low fat oxidation rate is a risk factor of fat gain or fat re-gain after weight loss. Conclusion Further research is needed to identify new risk factors of childhood obesity, both in the genetic and environmental areas, which may help to develop more effective strategies for the prevention and treatment of obesity.

Notes: Abstract The mechanisms underlying motor neuron degeneration in amyotrophic lateral sclerosis are not fully understood. Recent studies suggest that apoptosis is involved in the abnormal neural death that occurs in this devastating disease. Presenilin-1, a transmembrane protein, seems to be implicated in apoptosis. To determine whether presenilin-1 intron 8 polymorphism has an influence in the course of amyotrophic lateral sclerosis, we examined this polymorphism genotypes in a large group of patients (n=72) with amyotrophic lateral sclerosis and in a random sample of 213 healthy individuals. The results showed a significant difference in genotype (P 〈 0.04) and allele (P 〈 0.03) distribution between patients and controls. These results suggest a possible intervention of presenilin-1 in the pathogenesis of amyotrophic lateral sclerosis.

Notes: Abstract This review describes differing profiles of vascular risk factors in different types of dementia. Although vascular risk factors are related to various types of strokes, their independent effect on the occurrence of poststroke dementia appears to be small. Various risk factors have been identified for microangiopathy-related cerebral abnormalities, such as white matter changes and lacunae, which are the core lesions for the development of a vascular dementia syndrome without stroke symptoms. Most consistently, arterial hypertension and diabetes mellitus have been found to be associated with such brain abnormalities. Diastolic blood pressure seems to be of particular importance as recent investigations demonstrate that this factor is related to the course of multiple lacunar strokes and the progression of white matter disease. Epidemiological studies report that various vascular risk factors including arterial hypertension, diabetes mellitus, and atrial fibrillation may also be associated with Alzheimer’s disease. There is also evidence of a direct relationship between Alzheimer’s disease and general atherosclerosis. Further investigations are needed to determine whether these associations are due to the weakness of diagnostic criteria, or whether vascular risk factors indeed modulate the clinical expression of primary degenerative dementia. Common susceptibility genes leading to shared risk factors may be one of the reasons for a higher coincidence of Alzheimer’s disease and vascular dementia than can be expected by chance. A modulatory effect of vascular risk factors in the development of primary degenerative dementia may extend treatment options.

Notes: Abstract Monoamine oxidase B (MAOB) metabolises dopamine and activates neurotoxins known to induce parkinsonism in humans and primates. Therefore the MAOB gene (MAOB; Xp15.21–4) is a candidate gene for Parkinson’s disease (PD). Longer length dinucleotide repeat sequences in a highly polymorphic GT repeat region of intron 2 of this gene showed an association with PD in an Australian cohort. We repeated this allele-association study in a population of 176 Chinese PD patients ¶(90 men, 86 women) and 203 age-matched controls (99 men, 104 women). Genomic DNA was extracted from venous blood and the polymerase chain reaction was used to amplify the appropriate regions of the MAOB gene. The length of each (GT) repeat sequence was determined by 5% polyacrylamide denaturing gel electrophoresis. There was no significant difference in allele frequencies of the (GT) repeat allelic variation between patients and controls (χ2 = 2.48; df = 5, P 〈 0.75). Therefore the longer length GT repeat alleles are not associated with PD in this Chinese population. Possible reasons for the discrepancy between Chinese and Australian populations include a different interaction between this genetic factor and environmental factors in the two populations and the possibility that the long length GT repeat alleles may represent a marker mutation, genetically linked to another susceptibility allele in whites but not in Chinese. Methodological differences in the ascertainment of cases and controls in this cohort could also explain the observed differences. Further study is required to determine whether the longer length GT repeat alleles are true susceptibility alleles in PD.

Notes: Abstract Genetic studies have detected an association between the presence of the τ gene A0 allele and patients with progressive supranuclear palsy (PSP). This study examined whether patients with this polymorphism exhibit distinct demographic or clinical characteristics. We studied 26 patients who fulfilled clinical criteria for the diagnosis of PSP, 20 who had the A0/A0 genotype and 6 who had other genotypes. A questionnaire on demographic data, past medical history, familial history, and initial symptoms was completed as part of the consultation. A complete neurological examination was performed and PSP symptoms were quantified following Golbe’s PSP disability scale. We found a significant difference in the age at onset of PSP symptoms, which was 65.9 ± 5.3 years in the A0/A0 group and 71.2 ± 5.6 in the non-A0/A0 group (P = 0.016). There were no significant differences in the years from disease onset between the two groups. Symptom severity did not differ significantly in patients with the different A0/A0 genotypes. The detection of significantly lower age at onset with the A0/A0 alleles is consistent with the known association of this genotype as a risk factor for PSP. No significant differences were detected in symptom severity between the two groups of patients.

Notes: Abstract We found that 19% (9/47) of healthy siblings of patients with clinically definite multiple sclerosis had an intrathecal immunological reaction with two or more 2 CSF-enriched oligoclonal bands (OCBs), in contrast to (4%) (2/50) unrelated healthy controls. Furthermore, in this group of nine healthy sibs the measles CSF IgG antibody titers were higher than that of the other sibs and that of controls. There were also differences in the serum titers for measles IgG antibody, which were higher in the group of all healthy sibs than in healthy volunteers, and (as with CSF titers) higher in the subgroup of healthy sibs with two or more 2 CSF-enriched OCBs than the other sibs. Thus a significant proportion of healthy siblings to MS patients have a partially hyperimmune condition similar to that occurring in MS, which in 19% manifested itself as an OCB reaction, in 9% as increased CSF measles IgG antibody titers, and in 21% as increased serum measles IgG antibody titers, these phenomena tending to occur in the same individuals. This condition is characterized by CSF-enriched OCBs with undefined specificity, although some increased antiviral reactivity is found both in the serum and CSF. While it needs further characterization, a genetic trait interacting with common infections is suggested. The recurrence risk of this condition is approximately five times higher than the 3–4% recurrence risk for manifest MS reported for sibs.

Notes: Abstract  The new millennium beckons for novel advances in the diagnosis and treatment of pediatric neurosurgical conditions. Almost every aspect of pediatric neurosurgery has changed over the last decade. Undoubtedly with the application of knowledge in molecular biology to human disease many aspects of neurosurgery, especially neuro-oncology and the field of neuro-developmental anomalies, will change appreciably over the next decade. Overall, the trend in surgery in general and neurosurgery in particular is toward less invasive procedures and possibly non-surgical interventions. This review will briefly cover many of the important areas of pediatric neurosurgery. We will describe the state-of-the-art of our subspecialty and discuss possible future directions.

Notes: Abstract  The (in)compatibility genotypes of two self-compatible sweet cherry selections, JI 2420 and JI 2434, originating from the John Innes Institute were re-examined. The selections and seedlings derived from them were analysed for stylar ribonucleases, which are known to correlate with S alleles, and the outcome of test crosses was recorded. JI 2420, which had been reported previously as S 3 S 4 ", where " indicates loss of pollen activity, was deduced to have the genotype S 4 S 4 ’. For JI 2434, which had been reported previously as S 3 S 4 0 , S 3 S 3 0 or S 3 S 3 ", where 0 indicates loss of pollen and stylar activity, two different clones were identified. One, at East Malling, was deduced to be S 3 "S 4 ; the other, at Ahrensburg, appeared to be S 3 S 3 " or S 3 S 3 0 .

Notes: Abstract  An enriched microsatellite library of the mangrove species Avicennia marina was constructed, in which 85.8% of the clones contained microsatellite sequences. Of the microsatellite repeat sequences isolated, 55.0% were di-nucleotides, 34.2% were tri-nucleotides, 50.0% were perfect, 24.2% were imperfect, and 15.0% were compound. Four different di-nucleotide repeats were isolated with repeat lengths ranging from 5 to 33; ten different tri-nucleotide repeats were isolated with repeat lengths ranging from 3 to 25. The most common di-nucleotide was the AC/TG repeat; the most common tri-nucleotide was the CCG/GGC repeat. Sixteen microsatellite sequences were selected for primer design, and 6 primers were selected to investigate the polymorphism detected among 15 individuals of A. marina from three natural populations in Australia. A total of 40 alleles were detected at 6 microsatellite loci. The number of alleles per microsatellite locus ranged from 5 to 13. On average, 7 alleles were detected per locus. All microsatellite loci showed high levels of gene diversity (heterozygosity), with values ranging from 0.53 to 0.88; the mean value of gene diversity was 0.70. Microsatellite loci were also tested for conservation across Avicennia species. There was a decline in amplification success with increasing divergence between Avicennia species. The results indicate that microsatellites are abundant in the Avicennia genome and can be valuable genetic markers for assessing the effects of deforestation and forest fragmentation in mangrove communities, which is an important issue for mangrove conservation and afforestation schemes.

Notes: Abstract In the search for genetic factors contributing to tardive dyskinesia, dopamine receptor genes are considered major candidates. The dopamine D3 receptor is of primary interest as dopamine D3 receptor knock-out mice show locomotor hyperactivation resembling extrapyramidal side-effects of neuroleptic treatment. Furthermore, Steen and colleagues (1997) recently reported an association between tardive dyskinesia and a dopamine D3 receptor gene variant. In the present study we tried to replicate this finding. We investigated 157 patients with schizophrenia or schizoaffective disorder receiving long-term neuroleptic medication who never or persistently displayed tardive dyskinesia. As advanced age is a main risk factor for tardive dyskinesia, we also compared older patients with a long duration of schizophrenia not displaying tardive dyskinesia to younger patients with a shorter duration of the illness displaying tardive dyskinesia. However, we found no evidence that the dopamine D3 receptor gene is likely to confer susceptibility to the development of tardive dyskinesia.

Notes: Abstract An association between long alleles of a variable number tandem repeat (VNTR) polymorphism in the dopamine receptor D4 gene and the extraversion related personality traits Excitement and Novelty Seeking has been reported in healthy subjects. In an attempt to replicate the previous findings, 256 healthy Caucasian volunteers were analysed for a potential relationship between the dopamine receptor D4 exon III VNTR polymorphism and Extraversion as assessed by the Revised Neo Personality Inventory (NEO PI-R). The present study did not yield evidence for an association between Extraversion and the dopamine receptor D4 polymorphism.

Notes: Abstract An increased amount of the intercellular adhesion molecule (ICAM) 1 molecule has been found in the blood of actively relapsing multiple sclerosis (MS) patients, but is unclear whether this enhanced expression is partially causative of the MS process, or whether it is merely an epiphenomenon of the inflammatory-immunological reaction. Using the transmission disequilibrium test (TDT), we studied exon 4 and exon 6 polymorphism of the ICAM-1 gene from 157 families with both parents, one affected and one healthy sib coming from Sardinia, an Italian island having a high incidence and prevalence of MS. TDT did not show variation in the expected 50:50 frequency in transmission in either healthy or affected sibs, using phenotypic or genotypic analysis. Moreover, independence from the predisposing HLA-DRB1-DQA1-DQB1 haplotype was confirmed by TDT analysis performed on the patients stratified according to the presence or absence of the HLA-DRB1, DQA1, DQB1 Sardinian predisposing haplotypes. Our data suggest that the increased expression of the ICAM-1 molecule observed in both blood and periplaque microvessels may be considered a consequence of the inflammatory process rather than the result of a genetic variation.

Notes: Abstract  The potato cultivar ’Shepody’ is susceptible to a number of potato viruses including potato virus Y (PVY, potyvirus) but was found to possess extreme resistance to another potyvirus, potato virus A (PVA). ’Shepody’ plants were resistant to PVA infection in manual and graft inoculations. PVA replication was not detected in any of the inoculated plants by ELISA, an infectivity assay and RT-PCR. However, ’Shepody’ plants grafted with shoots containing PVA developed a novel symptomology which resembled a virus infection in appearance and in rate of translocation to the entire plant. Efforts to transmit the symptom-inducing agent manually failed. Graft-inoculation to potato virus indicator plants and PVA-susceptible potato plants showed that the symptom inducer was PVA at an extremely low concentration, detected using RT-PCR followed by Southern blot assay. Tubers from grafted but resistant ’Shepody’ plants had necrotic surfaces and internal spots. PVA was detected from necrotic areas but not from the non-necrotic ones. However, plants resulting from necrotic tubers were free from aerial leaf symptoms observed in grafted plants and produced non-necrotic normal tubers. A trace-back of the parental lineage of ’Shepody’ indicated that the resistance had been introgressed from the cultivar ’Bake King’. Analysis of progeny of a cross of resistant ’Shepody’ to the susceptible ’Goldrus’ indicated that this resistance is controlled by two independent dominant complementary genes in contrast to monogenic resistance reported for other potato viruses.

Notes: Abstract The importance of visual evoked potential (VEPs) and electroencephalography for diagnosing and distinghishing the infantile (INCL), late-infantile (LINCL) and juvenile (JNCL) forms of neuronal ceroid lipofuscinoses (NCL) is well established. Variant forms with protracted clinical courses and atypical symptoms have been described recently, whose neurophysiological characteristics sometimes overlap those of LINCL and JNCL. It is unclear whether these variant forms are due to phenotypic variability of known genetic defects, or represent new mutations. Twenty-eight NCL patients have been diagnosed at our institute; a proportion of them were investigated genetically. In 17 we performed neurophysiological investigations including VEPs, brainstem auditory (BAEP) and upper limb somatosensory (SEP) evoked potentials. We found typical and diagnostic electrophysiological involvement of the visual system in 8 patients with classic forms of NCL. Furthermore, the distinctive features of the multimodal evoked potentials in most of the six patients with variant NCL suggest that these are distinct genetic entities.

Notes: Abstract We performed a clinical and genetic study of patients affected by cavernous angiomas (CA) of the nervous system. We examined initial signs and symptoms in sporadic and familial cases. We obtained clinical, neuroimaging and genetic data on 15 Italian patients with CA of the nervous system with positive, doubtful or apparently negative family history. Genetic markers surrounding three different gene regions (7q, 3q and 7p) were analysed. In one small family, genetic linkage was consistent with all chromosome loci. In another family with the unusual association of cerebral and spinal CA, linkage with chromosome 7q and, likely, 7p was excluded, while linkage with locus 3q was possible. Our results indicate that Italian families with CA may show genetic heterogeneity. Non-specific and subtle onset symptoms hide the presence of CA within families. Patients with multiple CA may have silent cerebral lesions confirming the low penetrance of clinical signs in spite of radiological ones.

Notes: Abstract We present the clinical profile of a group of patients with myoclonus and dystonia sensitive to alcohol and address these cases in the context of essential myoclonus. Six patients from 4 families were selected: 4 men and 2 women with myoclonus affecting predominantly the arms. Active movements of these segments elicited the dystonic and myoclonic movements. A marked improvement with alcohol intake was seen. Laboratory findings including EEG, SSEP, and cranial CT and MRI were normal. Surface EMG recording showed bursts with duration of 30–112 ms in 3 patients. One patient showed a triphasic recording pattern (agonist-antagonist-agonist) of ballistic type. Our findings suggest that the myoclonus-dystonia disorder is present in Brazilian patients.

Notes: During recent years attempts have been made to formulate a viscosity-concentration relationship. The method of Huggins, in introducing a factor k′ as a hydrodynamic correction factor is examined, and in particular the attempts to draw conclusions relating k′ to the thermodynamic properties of the solution. An explanation is offered to correlate the experimental viscosity-concentration relationship and the change of solvent. A possible method for the actual calculation of concentration effects has been applied to the case of a suspension of spherical particles, for which, as a first approximation, a value of 10.6 for the coefficient of the c2 term has been obtained.

Notes: Tensile strengths of natural rubber samples quantitatively crosslinked with decamethylene dis-methyl azodicarboxylate have been determined. The proportion of the azo vulcanizing agent was varied 80-fold, the fraction p of cross-linked units in the products ranging from 0.10x 10-2 to 8.0 x 10-2. In spite of the small dimensions of the test specimen (cross section 0.10 in. by about 0.005 in.), the average error for a single observation is similar to that obtained in conventional testing procedures applied to specimens vulcanized with sulfur and accelerators. Deviations from the mean for 262 tests on 15 different cures are well represented by a Gaussian error function; a slight intimation of skewness is evident only at the extremities of the distribution of deviations. These results are incompatible with the commonly held view that rupture of the sample takes place at the “weakest link” in the series of flaws inevitably occurring along the specimen. It would appear that the ability to withstand tensile stress (applied in a specified manner) is an inherent characteristic of the bulk material. The rapid increase in tensile strength with the degree of crosslinking p for small values of this quantity is consistent with the conclusion, previously reached in the investigation of the physical properties of butyl rubber (6) that the tensile strength is directly related to the fraction of the structure which is permanently oriented by stretching. At higher degrees of cross-linking (at ρ x 100 = 1.0 to 1.5, depending on the molecular weight of the rubber) the tensile strength passes through a maximum and then declines steadily to quite low values for higher ρ's. This adverse effect of higher degrees of cross-linking is believed to result from the diminished elongation at which crystallization sets in and, hence, the smaller fraction of the network elements sufficiently oriented to participate in crystallite formation. Modification of up to 7% of the isoprene units of the rubber with the monofunctional compound, ethyl azodicarboxylate, depresses the tensile strength of the disazo vulcanized rubber relatively little. Evidently, the limited extent to which these modified (or copolymer) chains may enter into crystallization is adequate to bring about high tensile strength. Lack of direct correlation between modulus and tensile strength for rubbers vulcanized with various sulfur-accelerator combinations can only be explained by assuming that conventional vulcanization processes are accompanied to varying degrees by chain scission reactions. When vulcanized rubber is “over-cured,” or heat aged, chain scission becomes excessive.

Notes: The infrared and ultraviolet absorption spectra of Koresin are very similar to those of an acid-catalyzed p-tert-butylphenol-acetal- dehyde polymer. This is believed to be evidence that Koresin has Structure I. A variety of phenol-aldehyde resins have been prepared for comparison with Koresin. The ratings of some of these materials as tackifiers have been reported. These furnish further evidence that the molecular weight of a phenol-aldehyde resin is important in its tackifying action. An alkaline-catalyzed condensation product of acetylene and p-tert-butylphenol shows no tackifying action and has no free hydroxyl in the polymer as judged by its infrared pattern.

Notes: The paper deals with a tentative plan to extend quantitative x-ray measurements for determining the degree of crystallinity of polymers (as used earlier in cellulose determinations), to the investigation of rubber, polythene, and a polyamide. Strictly monochromatized copper radiation was used. The results show that further work along these lines may be promising. The raw rubber sample used was identical with one of those investigated by Goppel and by Arlman. It yielded a crystallinity figure higher than that reported by Goppel, but conformed with that found by Arlman. The figures obtained for polythene at different temperatures are compared with those derived from density and heat capacity measurements by other workers. The degree of crystallinity of polythene at room temperature is found to be ∼ 55%, and in samples of polyhexamethylene sebacamide, previously treated in different ways, figures between ∼50 and 70% are obtained. It is shown that the possibility of using the background intensity as a measure of the disordered fraction is confined to not too high angles of diffraction. A method is described (and experimentally checked) allowing for reducing the curves of intensity distribution as a function of 2θ as observed in various polymers to a comparable scale. It is further emphasized that, in polymers where hydrogen bonds play a decisive role in intermolecular cohesion, the x-ray results suggest that the “crystalline” or ordered fraction may to a considerable extent involve states of two-dimensional order.

Notes: o-Hydroxystyrene did not copolymerize with styrene and butadiene in GR-S-type systems. A terpolymer of these three monomers was obtained by copolymerizing o-acetoxystyrene, styrene and butadiene in carbon tetrachloride solution by the action of stannic chloride followed by hydrolysis of the acetate groups in the polymer with dilute hydrochloric acid in dioxane solution. The polymer thus obtained did not improve the tack of GR-S.

Notes: During a definite polymerization time the rate of uncatalyzed polymerization of styrene may be decreased by the use of activated carbon. The intrinsic viscosities of the polymers formed may be either increased or decreased by the addition of active carbon, depending upon the activity of the carbon sample used.

Notes: Refractive index-temperature and volume-temperature data for polyvinyl acetate and polybutyl acrylate have been determined and used to calculate the specific refractivity as a function of temperature by the Lorentz-Lorentz and the Eyckman equations. The results show a variation of specific refractivity with temperature which exceeds experimental error. The variation is evident as an increase of specific refractivity with temperature above Tm and suggests experiments which will show the increase more clearly. A theoretical justification for the increase of specific refractivity with temperature in polymers is discussed.

Notes: Various mechanisms which have been proposed for the reaction between ferrous iron and hydrogen peroxide are reviewed. Two of these mechanisms appear equally satisfactory on the basis of present evidence: that of Bray and Gorin, involving formation of tetravalent (ferryl) iron, and that of Haber and Weiss, involving formation ofhydroxyl and perhydroxyl radicals. Mechanisms involving these intermediates have been developed for the ferric iron-catalyzed decomposition of hydrogen peroxide; the mechanism of Bray and Gorin appears satisfactory, while that of Haber and Weiss leads to certain inconsistencies. A mechanism with ferrous iron and hydroxyl and perhydroxyl radicals as intermediates is presented, which accounts for the experimental observations in the ferric iron-catalyzed decomposition of hydrogen peroxide. The reaction between hydrogen peroxide and ferrous iron induces the reaction between hydrogen peroxide and various organic compounds; this induced reaction (termed a Fenton reaction) is a chain reaction which is initiated by the active intermediates (ferryl iron or hydroxyl radical) formed in the primary reaction. The determination of hydrogen peroxide by reaction with ferrous iron, if carried out in the presence of various organic compounds (termed promoters), gives incorrect results, due to induced oxidation of the promoters; other compounds, termed suppressors, reduce the extent of this induced oxidation of promoters. It appears that both types of compounds react with ferryl iron or hydroxyl radical to form radicals, which if formed from promoters, reduce ferric iron or hydrogen peroxide, while the radicals formed from suppressors oxidize ferrous iron. These considerations are of particular importance in the determination of organic hydroperoxides. The reaction between hydrogen peroxide or organic peroxides and ferrous iron can induce, or initiate, the polymerization of vinyl monomers; this is an example of redox polymerization, which is of considerable practical importance at present.

Notes: Cellobiose wird als Glykolsäure-glykosid nach der Azid-methode mit Protein kondensiert. Ferner werden aus Lacto-bionsäure und Proteinen nach der Azid-methode Lacto-bionyl-proteine synthetisiert.

Notes: 2-Chlorbutadien-1,3 (Chloropren) bildet schon bei niedrigen Temperaturen mit molekularem Sauerstoff ein Peroxyd. Die Bildungsgeschwindigkeit dieses Peroxyds ist so groß, daß es schwierig ist, peroxydfreies Chloropren herzustellen. Dies gelingt durch sorgfältige Destillation unter reinstem Stickstoff.Die Versuche zur Isolierung des Chloroprenperoxyds ergaben wegen seiner leichten Zersetzlichkeit keine befriedigenden Ergebnisse. Die quantitative Bestimmung des Peroxyds in Chloropren gelingt nach den üblichen Methoden nicht oder nur sehr schwierig. Chloroprenperoxyd oxydiert Antioxydantien, wie z. B. Phenyl-β-naphthylamin, zu gefärbten Produkten. Da Phenyl-β-naphthylamin die weitere Autoxydation des Chloroprens unterbindet, kann auf dieser Grundlage eine photometrische Bestimmung des Peroxyds durchgeführt werden.Die Geschwindigkeit der Sauerstoffaufnahme von Chloropren bei 0°C wurde volumetrisch gemessen. Die Sauerstoffaufnahme ist ein autokatalytischer, gleichförmig beschleunigter Vorgang. Er wird von Tetralinperoxyd stark beschleunigt, nicht aber von Benzoylperoxyde. Es wurden andere katalytisch wirkende Stoffe und der Einfluß des Lichtes untersucht.Da Chloroprenperoxyd die Polymerisation des Chloroprens auslöst und stark beschleunigt, ist es zweckmäßig, für die Stabilisierung dieser ungesättigten Verbindung solche Stoffe anzuwenden, die nicht nur die Polymerisation, sondern auch die Autoxydation hemmen. Die stabilisierende Wirkung der Antioxydantien wird bei Anwesenheit von Chloroprenperoxyd und Chlorwasserstoff nach einer Induktionsperiode durchbrochen. Dies kann dadurch erklärt werden, daß Phenyl-β-naphthylamin im Falle des Chloroprenperoxyds durch Oxydation, im Falle des Chlorwasserstoffs als Salz unwirksam gemacht wird.

Notes: Es wird ein einfaches Verfahren angegeben, den Transport von Wasser durch Textilfaserschichten zu messen, die einerseits in Wasser tauchen und andererseits an Luft mittlerer relativer Feuchtigkeit grenzen. Proteinfasern transportieren das Wasser langsam, Baumwolle rascher und Viskosekunstfasern sehr rasch.

Notes: Es wird der Einfluß von Seitenketten auf die Höhe der Viskositätszahl Zη von niedermolekularen Estern untersucht. Bei Dicetylmalonestern und Dicetylessigestern hat die Länge der Estergruppe keinen Einfluß auf die Höhe der Viskositätszahl. Bei substituierten Malonsäuredicetylestern resp. Disterylestern ändert sich dagegen die Viskositätszahl mit der Länge der in die CH2-Gruppe substituierten Alkylreste, und zwar ist sie bei kurzkettigen Substituenten kleiner, bei langgliedrigen größer als bei den unsubstituierten Verbindungen gleicher Kettenlänge. Das gleiche Verhalten zeigen β-alkylsubstituierte Stearinsäureester. Es wird weiter versucht, inwieweit das Einsteinsche Viskositätsgesetz in veränderter Fassung zur Klärung dieses Viskositätsverhaltens herangezogen werden kann.

Notes: Da nach den üblichen technischen Verfahren die Isolierung von Pektinen unvermeidlich mit einem gewissen Abbau verbunden ist, wurden die schonendsten Bedingungen festgestellt, unter denen es noch möglich ist, Pektin aus dem Fruchtfleisch von Äpfeln in ausreichender Menge zu gewinnen. Durch Wahl des günstigsten Reifezustandes, Ausschaltung einer Enzymtätigkeit, Einhaltung möglichst neidriger Extraktionstemperaturen und eines geeigneten pH konnte ein wenig abgebautes Pektin crhalten werden, dessen Methoxylgehalt dem für eine vollständig veresterte Polygalakturonsäure berechneten sehr nahe kommt. Die Molekulargröße wurde viskosimetrisch an einem aus diesem Material gewonnenen Pektinnitrat bestimmt, das nach einer schonenderen Nitrierungsmethode als der bisher üblichen hergestellt war. Die erhaltenen Werte liegen über den bisher beobachteten. Das im Apfelsaft vorhandene „freie Pektin“ wurde als niedriger molekular befunden.

Notes: Aus einer Zusammenstellung von Viskositätsmessungen an niedermolekularen Kettenmolekülen mit Doppelbindungen geht hervor, daß die trans-Formen eine höhere und die cis-Formen eine niedrigere Viskosität haben als die analogen gesättigten Verbindungen. Die verschiedene Viskosität von trans-, cis- und gesättigten Verbindungen kann mit der verschiedenen Form und Elastizität der Kettenmoleküle erklärt werden. Maleinsäureester und Maleinsäurepolyester lassen sich mit Brom als Katalysator in die entsprechenden Fumarester umlagern.

Notes: Es wurde die Polymerisationsgeschwindigkeit des Vinylchlorids bei 50° unter Zusatz verschiedener Mengen Benzoylperoxyd als Katalysator untersucht, indem der Umsatz das Molekulargewicht und die Zeitdauer beginnender Trübung durch Ausfallen des Polymerisats bestimmt wurde.Der Umsatz steigt zunächst langsam, dann schneller mit der Zeit an; über 80 - 90% nimmt er nur noch sehr langsam zu, so daß die letzten 1 - 2% praktisch nicht mehr polymerisieren. Mit sinkender Katalysatorkonzentration wird die Reaktion langsamer, derart, daß sich die Umsatzzeitkurven durch Dehnung der Zeitachse proportional der Wurzel aus der ursprünglichen Katalysatorkonzentration zur Deckung bringen lassen. Bis zu 70 - 80% läßt sich der Umsatz durch die Gl. u = (eat  -  1)b gut darstellen, wobei b = 0,1 und a = 0,240 · √c20 zu setzen ist.  -  Gegen Ende der Reaktion ließ sich im restlichen Monomeren Salzsäure nachweisen.Das Molekulargewicht nimmt mit steigender Menge Benzoylperoxyd und Sauerstoff deutlich ab; bei mäßigen Peroxydkonzentrationen wird dieser Effekt in der Streuung der Versuchswerte nicht sichtbar.  -  Die Zeit bis zur beginnenden Trübung ändert sich umgekehrt proportional der Wurzel aus der Katalysatorkonzentration und ist ferner unter reinem Sauerstoff größer, unter Stickstoff kleiner als unter Luft.Der Katalysator verschwindet während der Polymerisation, und zwar in um so stärkerem Maße, je höher seine ursprüngliche Konzentration, und um so weniger, je größer die Menge an Sauerstoff ist.  -  Mit Kaliumpersulfat erfolgt die Polymerisation nur in der wäßrigen Phase.Mit den Beobachtungen im Einklang steht das folgende Reaktionsschema (B = Benzoylperoxyd, M = monomeres Vinylchlorid). Die Hemmung der Polymerisation durch eine Anzahl von dritten Stoffen wurde orientierend, etwas eingehender die durch Styrol untersucht. Schwache Reduktionsmittel, Vinylderivate und einige anorganische Stoffe hemmen die Polymerisation, während chemisch indifferente Stoff sie nicht beeinflussen. Die Hemmung beruht vermutlich auf vorzeitigem Kettenabbruch.

Notes: Der bei Pektinpräparaten festzustellende P2O5-Gehalt in der Asche stammt teils von anorganischen und organischen Begleitstoffen (Phosphatiden), teils aber auch von Veresterungen der Pektinketten durch H3PO4; im Protopektin der Pflanzen hat man Vernetzungen der Pektinketten durch H3PO4-Brücken zu „Übermolekülen“ anzunehmen, die zahlenmäßig jedoch gegenüber den Vernetzungen durch mehrwertige Metallionen über die Karboxylgruppen zurücktreten.

Notes: 1Die Untersuchungen von Ohara (1933) über das polarisationsoptische Verhalten des Seidenfibroins wurden einer kritischen Betrachtung unterzogen und dabei Abweichungen von der Wienerschen Theorie festgestellt.2Die Hauptbrechungsindizes von Fibroinfäden, die 40 Stunden bei 100°C über P2O5 getrocknet worden waren, wurden nach der Immersionsmethode von Becke gemessen und zu für eine Wellenlänge von 589 mμ gefunden. Daraus resultiert eine Doppelbrechung von 0,0506 und für den Schwerpunkt des weißen Lichtes bei 550 mμ eine solche von 0,0514.3Imbibitionsversuche an trockenem und feuchtem Fibroin ergeben eindeutig das Fehlen eines Stäbchendoppelbrechungseffektes. Dies steht im Gegensatz zu den Untersuchungen von Ohara. Der mit Hilfe der Imbibitionsmethode gefundene Wert der Doppelbrechung stimmt mit dem der Immersionsmethode gut überein.4Die Abweichungen von diesem Wert in Wasser und wäßrigen Gemischen als Imbibitionsmedien lassen sich weitgehend mit Hilfe der Quellung erklären.5Durch Quellung und nachfolgende Imbibition kann keine Verstärkung eines etwa nur schwach entwickelten Stäbchendoppelbrechungseffektes erreicht werden.6Elektronenoptische Aufnahmen vermitteln Einblick in den Feinbau des Fibroins, welches aus feinen Fibrillen mit ganz verschiedenen Durchmessern besteht, die sehr fest und dicht gepackt sind.

Notes: Die molekulare Ultraschallgeschwindigkeit ist eine additive Eigenschaft für substanzen mit niedrigem Molekulargewicht und ergibt sich mit großer Annäherung aus der Summe der Geschwindigkeiten der verschiedenen Radikale, die das Molekül bilden.Die Übereinstimmung zwischen der experimentell festgestellten Geschwindigkeit und der auf Grund der Geschwindigkeiten der Radikale berechneten scheint besser zu sein als die auf Grund der Bindungsgeschwindigkeiten nach Lagemann und Corry berechneten. Wie schon von diesen Forschern angegeben, liefern die Bindungsgeschwindigkeiten zufriedenstellende Ergebnisse nur für unverzweigte Verbindungen.In den Verbindungen mit niedrigen Molekulargewichten führt die Gegenwart von Verzweigungen in den Molekülen zu einer Erniedrigung der molekularen Ultraschallgeschwindigkeit, die jedoch sehr geringfügig ist (12 Einheiten für die Methyl- und 20 für die Äthylgruppe in anderen Stellungen als  - 1 und  - 2).Für Verbindungen mit hohem Molekulargewicht und unverzweigter Kette stimmt der Wert der grundmolekularen Ultraschallgeschwindigkeit, d. h. bezogen auf die Grundgruppe, mit den auf Grund der Bindungsgeschwindigkeiten und auch mit den auf Grund der Radikalgeschwindigkeiten berechneten überein. Für verzweigte Moleküle ist die Übereinstimmung für die Radikalgeschwindigkeit besser, wobei die Erniedrigung der grundmolekularen Geschwindigkeit infolge der Verzweigungen höher ist im Falle von Verbindungen mit hohem als mit niedrigem Molekulargewicht.Die Bestimmung des Verhältnisses zwischen der experimentellen und berechneten Geschwindigkeit kann ein Mittel darstellen, um Anzahl und Größe der Verzweigungen zu bestimmen. Diesem Verhältnis ist die Bezeichnung „Formfaktor“ gegeben worden.Der Formfaktor ist gleich 1 oder etwas höher für die unverzweigten oder wenig verzweigten Verbindungen mit hohem Molekulargewicht (Paraffine, Polyäthylene, Polyäthylenoxyd, Nylon), niedriger als 1 für die verzweigten Verbindungen: 0,90 im Naturgummi, der eine Methylverzweigung an jedem vierten Kohlenstoffatom in den langen Ketten trägt, und 0,79-0,80 in den Polyisobutylenen mit zwei Methylverzweigungen an jedem zweiten Kohlenstoffatom in der Kette.Niedrigere Werte als der Naturgummi und unwesentlich höhere als die Polyisobutylene weisen die Formfaktoren des Polyalfabutylens und des Polystyrols auf (0,82), die eine äthylische, bzw, eine phenylische Gruppe auf jedes zweite Kohlenstoffatom in der langen Kette besitzen; dies beweist auch einen Einfluß der Länge der Verzweigungen auf den Formfaktor in dem Sinne, daß letzterer um so mehr erniedrigt wird, je größer die Verzweigung ist.Der Einfluß der Häufigkeit der Verzweigungen und ihrer Länge auf den Formfaktor wird beim Polymethylmetakrylat bestätigt, da diese Verbindung den niedrigsten von uns festgestellten Formfaktor aufweist; diese Verbindung besitzt nämlich zwei Verzweigungen an jedem zweiten Kohlenstoffatom der Kette, und zwar eine Methylgruppe und eine methylierte Karboxylgruppe.Die Übereinstimmung der Formfaktoren des Buna und des hydrierten Buna mit dem des Polyalfabutylens ist ein weiterer Beweis, daß die nicht bei niedriger Temperatur ausgeführte Polymerisierung des Butadiens in den Stellungen 1 - 2 oder 2 - 3 und nicht in der Stellung 1 - 4 stattfindet. Dies steht im Einklang mit den kürzlich mitgeteilten Versuchsergebnissen von Hanson und Halverson bei gestrecktem Buna.Der niedrige Formfaktor des Polyvinylisobutyläthers (0,79) kann ein Zeichen für den Einfluß der sekundären Verzweigungen auf den Formfaktor sein.Schließlich bestätigt die Unveränderlichkeit des Formfaktors für alle untersuchten Polyisobutylene mit verschiedenen Molekulargewichten, daß für hochmolekulare Verbindungen die grundmolekulare Ultraschallgeschwindigkeit und demzufolge der Formfaktor vom Molekulargewicht unabhängig ist.

Notes: Durch Untersuchung der Kettenlängenverteilung von oxydative in Kupferoxydammoniaklösung abgebauten Buchen- und Fichtencellulosen wird gezeigt, daß ebenso wie bei Baumwoll- und Ramiecellulosen eine Vereinheitlichung bei Polymerisationsgraden zwischen 400 und 500 eintritt. Auch bei hydrolytisch abgebauten Produkten ist dieser Effekt zu bemerken, läßt sich jedoch wegen der Viskositätsanomalien nicht quantitativ auswerten. Aus den Befunden wird geschlossen, daß auch in Holzcellulosen im Abstand von ca. 500 Glucoseresten Lockerstellen vorhanden sind, die durch Oxydationsmittel und Säuren erheblich schneller gespalten werden als die β-glucosidischen Bindungen. Diese periodische Struktur ist für alle bisher untersuchten Cellulosearten im Abstand der Lockerstellen identisch, jedoch unterschieden durch das Verhältnis der Spaltungsgeschwindigkeiten. Aus elektronenmikroskopischen Aufnahmen wird geschlossen, daß die Lockerstellen in Ebenen senkrecht zur Faserrichtung angeordnet sind.

Notes: The conductance of a series of salts made by the addition of n-butyl bromide to 4-vinylpyridine-styrene copolymers (1.5 to 90 mole per cent vinylpyridine) has been measured in dioxane (∊′ = 2.2), ethylene dichloride (∊′ = 10.2), and a series of nitromethane-dioxane mixtures (16.0 ≤ ∊′ ≤ 39.4). Three independent arguments deduced from the data show that ionic association under the influence of interionic electrostatic forces must occur in solutions of polyelectrolytes in such a way that a certain average fraction of the counter ions accompany the large polycation and contribute nothing to conductance. First, the conductance at fixed copolymer composition and fixed salt concentration decreases with decreasing dielectric constant of the solvent medium. Second, at a given counter ion concentration in a given solvent, the conductance decreases with increasing pyridonium content of the chain. Third, for a given salt and solvent, the conductance decreases with increasing salt concentration at a rate much slower than that characteristic of simple electrolytes.

Notes: The method for the evaluation of the percentage crystallinity in cellulose preparations from x-ray intensity measurements, previously described in detail (J. Appl. Phys., in press) is reviewed briefly and new material presented consisting of crystallinity percentages between 8% and 70%. Cotton, flax, and ramie possess equal crystallinity (70%) and so do the majority of rayons, independent of their degree of orientation and including cuprammonium and Lilienfeld rayons. Cellulose acetates saponified under varying conditions also yield almost the same value as rayon (40%). The New product Fiber G (du Pont) holds an exceptional position with 53% crystalline substance. In the series of native celluloses, wood pulp has about 65%, Valonia 65-70%, and bacterial cellulose about 40%. By dry grinding of rayon, a powder was obtained containing only slightly less than 10% crystalline substance, which on recrystallization in water, yields 2 product having the same crystallinity as rayon. The difference between the heats of wetting of the criginal and the recrystallized powder affords additional support of the results obtained.

Notes: The discrepancies in the published work on the interaction of acetone and cellulose nitrate are discussed and explained. Vapor phase adsorption isotherms for the adsorption of acetone by cellulose nitrate have been determined with an adsorption balance. They have been shown to be independent of the crystalline-amorphous ratio of the polymer but dependent upon its nitrogen content. In cellulose nitrates which are completely soluble in acetone, no limiting adsorption has been found. Adsorption analysis (a modification of chromatography) has been applied to the determination of the liquid phase adsorption by cellulose nitrate of acetone from mixtures with petroleum ether. In terms of the liquid mixture concentrations, there appears to be limited adsorption, but this is shown to be due to the nonideal nature of the solutions of acetone and petroleum ether. When allowance is made for this, the liquid and vapor phase isotherms are the same within experimental error and do not support the existence of compounds of acetone and cellulose nitrate.

Notes: By means of chain transfer agents such as dodecyl mercaptan, polyisoprenes whose number-average molecular weights range between 300-1200 and which are liquid at room temperature have been prepared. The structure and physical properties of these substances have been investigated. Vulcanization of these liquids to rubberlike materials at room temperature and above is described.

Notes: The construction of a thermostated osmometer of the Fuoss-Mead pattern is described. The technique of preparation of bacterial cellulose membranes for osmotic measurements on high polymer systems is given. The permeability of such membranes may be controlled by growth to a thickness of 4-5 mm., drying in contact with a stainless steel surface, and reswelling in water or alcohol-water mixtures. The degree of reswelling required to give membranes suitable for use with polymers of a range of molecular weights is given. The factors affecting the behaviour of the membranes in the osmometer are discussed.

Notes: Le cas le plus simple pour calculer l'écart quadratique moyen entre les extrémités d'une chaǐne macromoléculaire est celui oùtoutes les rotations sont libres. Mais cette condition n'est généralement pas réalisée, aussi avons nous examiné dans cet article les résultats obtenus en introduisant une fonction de répartition symétrique pour les positions de chaque atome de la chaîne sur le cercle de base du cǒne de valence. Nous comparons les formules proposées jusqu'ici en représentant graphiquement leurs résultats (figs. 2 et 3). Cette comparaison montre que la formule de Kuhn et Taylor (8,9) est une approximation de celle que nous avons établié dans un article précédent (7) et a, de ce fait, un domaine de validité plus restreint. Ce domaine augmente avec le nombre des chaǐnons de la chaîne. En utilisant les fonctions de répartition proposées par Taylor nous représentons les valeurs de l'écart quadratique moyen en fonction de l'énergie d'interaction (figs. 6 et 7). Nous montrons ensuite que cette énergie d'interaction ne peut avoir la valeur calculée pour les vapeurs de carbures aliphatiques normaux mais est la somme de plusieurs termes et doit varier avec la nombre de chaǐnons et la température. Les formules établies permettent de prévoir deux aspects différents de la précipitation suivant qu'elle est effectuée par abaissement de la température ou adjonction d'un précipitant. Enfin, lorsque dans leurs rotations les atomes de la chaîne doivent passer par dessus des barrières de potentiel on peut prévoir des anomalies dans son comportement.

Notes: The strong ultraviolet absorption in the wave-length region 280-330 mμ shown by copolymers of acenaphthylene with styrene or methyl methacrylate is due to acenaphthylene residues. The spectra of samples of copolymer containing a small percentage of acenaphthylene are different from the spectrum of polyacenaphthylene. As a result of the comparison of the spectra of these copolymers with the spectra of acenaphthene and with the two forms of 1,1′-biacenaphthyl it is concluded that spectra of the copolymers can be explained as arising from the presence of pairs of acenaphthylene groups. Finally it is shown that the spectra can be used to estimate the acenaphthylene contents of the copolymers.

Notes: Es werdenn für cine Reihe von Erscheinungen bei Lösungen mit Fadenmolekülen, wie die künstliche Doppelbrechung, die Viskosität, den Depolarisationsgrad des molekularen Streulichtes, die Abhängigkeit vom Polymerisationsgrad und von der Form (Stäbchenform und statistische Grenzfälle) angegeben. Ferner werden Methoden zur Untersuchung von Verzweigungen und zur Betimmung der Mikroform mitgeteilt.

Notes: The osmotic pressures of two samples of poly-4-vinyl-N-n-butylpyridonium bromide (average D. P. 730 and 1900) were measured in 93% ethanol in the concentration range 0.02-0.20 g./100 cc. The osmotic pressures were higher than those of the corresponding parent polymers, due to partial dissociation of bromide ions. Because of the low dielectric constant ( ε′ = 28) of the solvent and the high concentration of positive charge in the polycations, however, a large fraction of the bromide ions (≥ 95%) were bound by electrostatic attraction to the cations and contributed neither to osmotic pressure nor to conductance. Unlike neutral polymers, the ratio (osmotic pressure over concentration) increases with dilution, due to increasing dissociation with dilution. Addition of an excess of a simple one-one electrolyte (lithium bromide) almost completely suppressed the dissociation of the polysalt and gave osmotic pressures of the same order of magnitude as those of the neutral polymers. The resulting curves were linear, with a considerably smaller slope than for the parent polymer. Combining the results on osmotic pressure with conductance data, the transference numbers of the polycations were estimated to be 0.28 and 0.52 for degrees of polymerization 730 and 1900 respectively. The conductance of lithium bromide is decreased by the addition of these polyelectrolytes, possible due to the association of an excess of anions to the polycations under the influence of their electrostatic fields.

Notes: The production of monomer during degradation of polystyrene in vacuo below 310°C. has been investigated. A mechanism has been proposed which explains the dependence of monomer formation on the initial breaks in the chain. The degradation in presence of oxygen has been studied. A mechanism for this reaction has been proposed which accounts for the type of curves obtained experimentally. The role of antioxidants has been briefly indicated. The elementary steps for the degradation in vacuo and in the presence of oxygen have been discussed.

Notes: Measurement of the infrared absorption spectrum of the lowmolecular liquid polymer formed at room temperature from gaseous isobutene using BF3 as a catalyst and D2O as a cocatalyst indicates that the dominant end groups in the final polymer are (CH3)3C and , and that the cocatalyst D2O undergoes partial conversation to H2O during reaction. These results substantiate the mechanism advanced by Polanyi and others, namely: (a) initiation through formation of the trimethyl carbonium ion by acceptance by isobutene of a proton (or deuteron) from the catalyst-cocatalyst complex, and (b) termination by explusion of a proton from a methyl group to the anionic complex fragment, with corresponding catalyst regeneration, i.e.:

Notes: An apparatus has been constructed which enables one to follow continuously the formation of monomer during degradation in vacuum. Experimental results are presented on the degradation of fractionated and unfractionated polystyrene over a range of temperatures from 340-400°C. in vacuum. A mechanism has been proposed which accounts satisfactorily for the apparent zero-order reaction and for the dependence of the rate of degradation on chain length. This mechanism allows one to estimate relative number average molecular weights and the number of weak points per original chain. The influence of a platinum surface on degradation has been indicated. The degradation of poly-alpha-methylstyrene has been investigated over a range of temperatures from 281 to 363°C. in vacuum. The mechanism of the degradation of branched polymer chains has been discussed. The degradation of cross-linked polystyrene containing various amount of m-divinylbenzene has been studied at 364°C. in vacuum. The reaction shows long induction periods depending on the amount of m-divinylbenzene and on the presence of benzoyl peroxide during polymerization. The degradation of polyethylene shows this polymer to be more heat resistant than polystyrene. Various grades of different average molecular weight have been investigated over a range of temperatures from 375 to 436°C. in vacuum. The energy of activation has been found dependent on chain length. A mechanism has been suggested to account for the observed experimental results.

Notes: Quantum yields for the inactivation of crystalline swine pepsin have been determined as a function of pH at 2537 A. The quantum yield is near a minimum at pH 4.08, at which point a value of 0.0019 was found, rises rapidly above pH 6, and shows a slight maximum near pH 2.7. The maximum is more pronounced with polychromatic light. The quantum yield (at pH 2.01) was found to be the same with either hemoglobin or casein as a substrate. Urea had no effect on the quantum yield although urea alone, 7 M, inactivates pepsin at an appreciable rate. Urea and light denaturation do not modify the absorption spectrum of pepsin in the same way. The data of Gates has been recalculated; it shows an increase of quantum yields with decreasing wave length. It has been concluded, from experiments with model substances, that inactivation can occur by the absorption of a quantum by any aromatic group in pepsin.

Notes: A relationship between tack temperature and molecular weight has been deduced and illustrated with polyvinyl acetate polymers. Provided the molecular weight is high enough to prevent cohesive failure, the adhesion of polyvinyl acetate to cellulose and aluminum is independent of molecular weight. The influence of humidity on adhesion of polymers to cellulose is shown. The influence of polymer composition on adhesion is illustrated with copolymers of vinyl acetate and methyl vinyl ketone and with styrene and methyl vinyl ketone. Above a mole fraction of ketone of 0.8, adhesion increases rapidly. The interdependence of tack temperature and composition on adhesion is exemplified with ethylene - vinyl chloride copolymers. A temperature dependence of adhesion is cited for copolymers containing maleic acid.

Notes: A number of equations are suggested for estimating intrinsic viscosity from one measurement of relative viscosity at a convenient concentration. Experimental data illustrate the validity of the equations.

Notes: The effect of increasing and decreasing temperature on the light transmission of polythene has been measured. On raising the temperature of a sheet of polymer the light transmitted increases steadily at an increasing rate until the sample becomes glass clear at the melting point (ca. 112°C.). On cooling from the melt the specimen becomes very opaque a few degrees below the melting point, then becomes much more transparent and thereafter the light transmission decreases as temperature falls, the transmission-temperature curve approximating to the curve for rising temperature. Changes in the spherulite structure of polythene film on heating and cooling have been observed under the microscope and recorded on a cinéfilm. Decay of spherulites on heating is seen not to occur by the reverse of the process by which they are formed from the melt, and the light transmission results are discussed in relation to the spherulitic structure of the polymer.

Notes: Die Polystyrole unterscheiden sich von anderen Vinylpolymeren dadurch, daß sie in guten Lösungsmitteln dem Staudingerschen Viskositätsgesetz gehorchen, wobei allerdings der Wert der Km -Konstante von den bei der Polymerisation vorliegenden Bedingungen abhängt. Die hierfür geltenden Beziehungen werden an Hand eines umfangreichen, aus zahlreichen Arbeiten entnommenen Materials geklärt.In schlechten Lösungsmitteln verhalten sich Polystyrole genau so wie andere Vinylpolymere (etwa zahlenmäßig übereinstimmend mit den Polyisobutylenen). Es gilt dann für sie die Gleichung von W. Kuhn.Zur Deutung der verschiedenen Km -Wurde bisher eine Verzweigung der Kettenmoleküle angenommen. Anknüpfend an Überlegungen von W. Kern und M. L. Huggins wird eine andere Deutung vorgeschlagen, die darauf beruht, daß jedes Monomere in einer 1- oder einer d-Form addiert werden kann. Bei tiefer Temperatur entstehen Kettenmoleküle mit alternierenden 1- und d-Bindungen, welche in guten Lösungsmitteln ziemlich steif und daher nur schwach geknäult sind. Bei höheren Temperaturen entstehen d-d- (bzw. 1-1-)Gruppierungen, die zu scharfen und starren Winkelungen der Kettenmoleküle Anlaß geben und dadurch die Km -Konstante herabsetzen. - Bei peroxydischer Polymerisation treten außerdem Verzweigungen auf.

Notes: Verbindungen zwischen Glucose und Eiweißstoffen lassen sich durch Kondensation der letzteren mit Tetracetyl-1-cyanato-d-glucose oder bequemer mit d-Glucose-1-cyanamid gewinnen. Der Umsatz mit d-Glucose-1-cyan-amid ist proportional dem Lysingehalt des Proteins und führt sehr wahrscheinlich zu d-Glucose-guanido-proteinen.

Notes: Oxy-cellulose wird nach der Azid-methode an Eiweißstoffe gebunden. In ihrer Kettenlänge nicht abgebaute Cellulose wird über ihre Glykolsäure-äther nach der Azid-methode mit Proteinen kondensiert. Es werden zwei Typen von Stoffen erhalten. Bei den kohlenhydratarmen ist jedes Cellulosemolekül von mehreren Proteinmolekülen umgeben. Bei den kohlenhydratreichen treffen mehrere Cellulosemoleküle auf jedes Proteinmolekül.

Notes: Durch Verestern von Gummi arabicum und Kuppeln nach der Azid-methode an Proteine wurden Arabicyl-proteine erhalten. Diese sind bei pH 7,5 - 8 gut löslich in Wasser, enthalten erhebliche Mengen an Polysaccharid und können bei pH 6 - 6,5 ausgefällt werden.

Notes: Vanadinpentoxydstäbchen wurden aus einem Sol in dicker Schicht auf Glas aufgetragen. Die Oberfläche des Belages wurde nach dem Polystyrol-Quarzabdruckverfahren elektronenmikroskopisch untersucht. Die Stäbehen sind einzeln sichtbar. Das Abdruckverfahren gibt aber die Stäbchengröße und -gestalt etwas verzerrt wieder.

Notes: The polymerization reaction which occurs when butene vapor is mixed with boron trifluoride gas has been studied under various conditions. It has been found that this polymerization occurs only if a third component, or cocatalyst, is present. The function of the cocatalyst has been investigated, and the mechanism of the polymerization reaction is discussed.