bluuebunny/crossref_metadata_2025 huggingface dataset:
A genome‐wide scan for a simulated data set using two newly developed methods
Authors: Hsu Li , Aragaki Corinne , Quiaoit Filemon , Wang Xiangjing , Xu Xiubin , Zhao Lue Ping
Published: November 2013

A genome‐wide scan of a simulated data set for fictitious disease genes was conducted using both semiparametric and nonparametric methods. The semiparametric model‐based method, which tests for linkage/linkage disequilibrium separately and together, correctly identified all three underlying disease loci along with two false positives through the linkage analysis. However, the nonparametric model‐free method which tests combined linkage/linkage disequilibrium, failed to yield any results due to the lack of linkage disequilibrium information in the data.
Environmental covariates: Effects on the power of sib‐pair linkage methods
Authors: Mandal Diptasri M. , Sorant Alexa J. M. , Pugh Elizabeth W. , Marcus Sherry E. , Klein Alison P. , Mathias Rasika A. , O'Neill Jennifer , Temiyakarn Loyrirk F. , Wilson Alexander F. , Bailey‐Wilson Joan E.
Published: November 2013

The effect of inclusion of environmental risk factors on the power of sib‐pair linkage methods was tested for a qualitative trait. It was found that inclusion of an environmental variable did not increase the power of the Haseman‐Elston (H‐E) sib‐pair nonparametric linkage analysis test. However, a significant increase in power was observed for both the H‐E and affected‐sib‐pair tests, even in small samples, when persons unexposed to the environmental risk factor were coded as unknown.
The effect of phenotype variation on detection of linkage in the COGA data
Authors: Birznieks Gunther , Ghosh Soumitra , Watanabe Richard M. , Mitchell Braxton D.
Published: November 2013

Error in phenotypic measurement can significantly compromise ability to detect linkage. We assessed the impact of introducing phenotypic measurement error on our ability to detect a quantitative trait locus in the Collaborative Study on the Genetics of Alcoholism (COGA) data. The impact of introducing three different types of errors was evaluated: 1) errors generated by sampling from a normal distribution; 2) errors generated by permuting phenotype values between subjects; and 3) errors generated by sampling from a uniform error distribution.
An evaluation of affected‐sib‐pair methods and transmission/disequilibrium tests for detecting genes underlying a complex trait
Authors: Shugart Yin Yao , Wehman Pat , Collins Andrew
Published: November 2013

For the analysis of complex traits, it is of interest to compare a few nonparametric methods such as affected‐sib‐pair (ASP) analyses and transmission/disequilibrium tests (TDT). The affected‐sib‐pair approaches we have examined here are ASP and ALL‐SP which are implemented in SIBPAIR program. We also applied the BETA program which has not so far been extensively compared with other methods. The study indicates that the ASP program and the BETA program give concordant results although BETA tends to give higher lod scores. However, when all sibs were included in the analysis (ALL‐SP), linkage signals became weaker, compared with ASP and BETA. The TDT detected 66 positive signals at a significance level of 0.05 and identified a true locus. Overall, our results suggest that affected‐sib‐pair analysis has reasonable power (p < 0.0001) to detect linkage given the disease model and the family structure specified in the GAW11 Problem 2 data set.
Oligogenic model selection using the bayesian information criterion: Linkage analysis of the P300 Cz event‐related brain potential
Authors: Blangero John , Williams Jeff T. , Iturria Stephen J. , Almasy Laura
Published: November 2013

The traditional likelihood‐based approach to hypothesis testing may not be an optimal strategy for evaluating oligogenic models of inheritance. Under oligogenic inheritance the number of possible multilocus models can become very large; there may be several competing linkage models having similar likelihoods; and comparisons among non‐nested models can be required to determine if a given multilocus model provides a significantly better fit to observed phenotypic variation than an alternative model. We propose an efficient Bayesian approach to oligogenic model selection that makes use of existing model likelihoods, and show how model uncertainty can be incorporated into parameter estimation.
Stratification techniques to explore genotype environment interactions
Authors: Wilk J.B. , Premkumar S. , Nicolaou M. , Myers R.H. , Maher N.E. , Harmon M.D. , Farrer L.A. , Destefano A.L. , Cupples L.A. , Couropmitree N.N.
Published: November 2013

Linkage analysis was performed on the GAW11 Problem 2 data set using stratification to explore the effects of the environmental risk factors and the differences between mild and severe phenotypes. Analysis of the four study populations stratified by the two risk factors identified regions on chromosomes 3 and 5 with significant evidence for linkage. Other loci were sought by removing families consistent with linkage to the chromosome 3 locus. Our studies identified a locus on chromosome 3 (markers 43–46) associated with the mild phenotype in the presence of risk factor 1 and with the severe phenotype independent of risk factor 1. This suggests that distinct allelic variants at the chromosome 3 locus may cause different forms of disease. The locus identified on chromosome 5 (markers 36–39) was linked to the severe phenotype, but exposure to factor 1 or 2 may have a protective effect. The regions on chromosomes 3 and 5 appeared to have independent roles in disease etiology. Evidence for two loci on chromosome 1 linked to the mild form was found. The methods successfully identified linkages and interaction consistent with the generating model.
Significant evidence for linkage of a simulated trait to D1G024–A conclusion reached using multiallelic transmission/disequilibrium tests
Authors: Ziegler Andreas , Hebebrand Johannes , Kastner Christian , Müller‐Myhsok Bertram
Published: November 2013

We applied three versions of the transmission/disequilibrium test (TDT) for detecting linkage in nuclear families using the a priori information of possibly present association. For our analyses we employed all marker data for a simulated trait. Results for replicate 11 showed significant linkage to D1G024 using the multiallelic Tmhet statistic and the extended TDT. The TDT for the most frequent parental allele which had been applied successfully in previous studies failed to detect linkage. This result may have happened because the data did not arise from a realistic simulation of the evolution of a real population, where mutations might be expected to occur against a specific haplotype. Simulation studies are required to elucidate the applicability of the TDT for the most frequent parental allele in realistic situations. Furthermore, guidelines have to be developed for how to pool categories in large, sparse contingency tables to obtain larger cell frequencies and lower degrees of freedom.
Cleaning genotype data
Authors: Broman Karl W.
Published: November 2013

The identification of genes contributing to variation in complex phenotypes requires genetic data of high fidelity. Thus, the identification of pedigree and genotyping errors is a crucial prerequisite to the analysis of data from a genome scan for disease genes. The problem has been given little attention in most gene hunting papers; the focus has often been on eliminating mendelian inconsistencies in order that the analysis may proceed, rather than on achieving the best possible data. Though a number of computer programs are available to assist in the identification of genotyping and pedigree errors, the process is still not completely automated. While the Collaborative Study on the Genetics of Alcoholism (COGA) data set for GAW11 is completely compatible with Mendel's rules, there are still some errors present. We inspected the COGA data for the presence of additional errors, and identified five possible pedigree errors.
A low density genome‐wide search for loci involved in alcohol dependence using the transmission/disequilibrium test, sib‐tdt, and two combined tests
Authors: Camp Nicola J. , Bansal Aruna
Published: November 2013

The transmission/disequilibrium test (TDT), sib‐TDT and two combined tests have been implemented in an attempt to identify loci across the genome that may be involved in alcohol dependence. Since these tests are based on the existence of association between marker and disease loci, the low‐density map used (13 cM) will have missed any disease loci situated between markers. Nevertheless, genome‐wide suggestive linkage results were found at three markers ‐ D6S474, D8S1715, and D12S372 ‐ two of which also gave nominally significant evidence by two‐point linkage analysis. These are regions that deserve further investigation with respect to their involvement in alcohol dependence, and in order to evaluate the relative efficacy of the different methods used.
Genetic analysis of personality traits and alcoholism using a mixed discrete continuous trait variance component model
Authors: Czerwinski Stefan A. , Mahaney Michael C. , Williams Jeff T. , Almasy Laura , Blangero John
Published: November 2013

Bivariate analyses can improve power to detect linkage. This paper describes one application of a bivariate variance component method for estimating joint likelihoods of a continuous and a discrete trait. This method is applied to the Collaborative Study on the Genetics of Alcoholism data set to investigate the relationship between personality traits derived from the tridimensional personality questionnaire (TPQ) and alcoholism. The results indicate that the novelty‐seeking subscale of the TPQ and alcoholism share a strong and significant genetic correlation (ρG = 0.83) and modest environmental correlation (ρE = 0.31). When both traits are considered jointly in a multipoint linkage model compared with the alcoholism trait alone, there is an improvement in the ability to detect and localize a quantitative trait locus on chromosome 4.
Exploring the impact of extended phenotype in stratified samples
Authors: Kovac Ilija , Rouillard Eric , Mérette Chantai , Palmour Roberta
Published: November 2013

We have performed initial nonparametric sib‐pair genome scans in the early (N = 52) and late (N = 53) onset subgroups of the COGA pedigrees, stratified near the median value of pedigree mean age of onset for ALDX1 diagnosis of alcoholism. Because the early group contained a higher proportion of smokers, traits of alcoholism, smoking, and addiction (defined as either alcoholism or smoking) were examined. Subgroups and phenotypic definitions influenced initial linkage results, corrected for the number of analyzed traits. Evidence for linkage to the ALDX1 alcoholism phenotype at the ADH3 functional candidate gene was increased in the late onset subgroup (Bonferroni corrected significance level < 0.002), as compared with the unstratified sample that replicated COGA linkage obtained in the same analysis; there was no evidence for linkage at this locus in the early onset subgroup. The theoretical implication of this result is that the loss of power due to contracting sample size through stratification may in some cases be more than offset by extraction of a more homogenous subgroup from the etiologically complex trait.
A multiple locus analysis of the collaborative study on the genetics of alcoholism data set
Authors: Lin Shili , Irwin Mark E. , Wright Fred A.
Published: November 2013

Parametric and nonparametric statistical methods have been applied to the alcohol dependence data set collected in the Collaborative Study on the Genetics of Alcoholism (COGA). Our nonparametric linkage analyses (NPL) were based on the Sall statistic of GENEHUNTER [Kruglyak et al., 1996] and the improved NPL statistic of GENEHUNTER‐PLUS [Kong and Cox, 1997]. Based on likely regions for alcohol susceptibility genes identified from our nonparametric analyses, we reanalyzed the data using several two‐locus models. We used the TMLINK program [Lathrop and Ott, 1990] in the LINKAGE package for these parametric analyses.
Exploring linkage for alcoholism using affection status and quantitative event related potential phenotypes
Authors: Lunetta Kathryn L. , Wilcox Marsha , Smoller Jordan , Neuberg Donna
Published: November 2013

Using genome‐scan data from the Collaborative Study on the Genetics of Alcoholism (COGA), we compared results of linkage analyses using a qualitative alcoholism phenotype to results of linkage analyses using event related potential (ERP) quantitative phenotypes, and compared our results to the results of Reich et al. [1998] and Begleiter et al. [1998]. We describe a general and simple strategy for identifying regions of the genome which may harbor genes involved in alcohol dependence which takes into consideration the results of both the affection status and ERP linkage analyses.
Evidence of linkage in subtypes of alcoholism
Authors: Mérette Chantai , Cayer Mireille , Rouillard Eric , Roy‐Gagnon Marie‐Hèlène , Guibord Pascal , Kovac Ilija , Ghazzali Nadia , Szatmari Peter , Roy Marc‐André , Maziade Michel , Palmour Roberta
Published: November 2013

We believed that subtyping alcoholism might be an efficient strategy for mapping susceptibility genes. Cluster analysis is one of the possible statistical techniques for such a purpose. We required that, ideally, the variables to be used in cluster analysis should be: 1) related to alcoholism, 2) related to the severity of alcoholism, and 3) familial, i.e., correlated within families. Only three variables met all three conditions. Those included age of onset of ALDX1, smoking, and TPQ‐HA. A global score of symptoms of alcoholism was systematically introduced as one of the variables composing a subset for cluster analysis, although this score did not show any familial aggregation. Our strategy led to a strong evidence of linkage at D15S230 in only 20 families whose members are mainly characterized by heavy smoking.
Sex‐based linkage analysis of alcoholism
Authors: Paterson Andrew D. , Petronis Arturas
Published: November 2013

A high degree of locus heterogeneity is likely in alcoholism, and linkage heterogeneity analysis may be helpful in mapping susceptibility loci. The genetic contribution to alcoholism in females may be higher than in males, and therefore sex of affected individuals was used in linkage analysis. Families with female alcoholics demonstrated evidence for linkage to chromosomes 1 Op 11‐p15 and 21q22.1‐q22.2 while those with male alcoholics did not provide evidence for linkage to these regions. Sharing of maternal and paternal alleles was also investigated separately, and evidence for linkage of maternal alleles on chromosomes 1 and 8, and paternal alleles on chromosome 2 was observed, suggesting parental origin effects. Mapping of complex traits may benefit from tests of linkage heterogeneity based on sex, and parental origin.
A genome‐wide search for susceptibility genes linked to alcohol dependence
Authors: Peterson L.E. , Barnholtz J.S. , Page G.P. , King T.M. , de Andrade M. , Amos C.I.
Published: November 2013

We performed two‐point linkage analysis during a genome‐wide search for susceptibility genes that predispose to alcohol dependence with the Collaborative Study on the Genetics on Alcoholism (COGA) data made available for the Genetic Analysis Workshop 11 (GAW11). For chromosomes 1 and 4 our findings supported results reported by Reich et al. [1998] based on the same data. We found similarity between our findings in regions on chromosomes 8 and 10 and reported results for schizophrenia linkage studies. Differences between our results with COGA data and those obtained by Reich et al. [1998] are due to our use of a lod score method versus their use of the affected relative pair (sib pair) method.
Analysis of principal component based quantitative phenotypes for alcoholism
Authors: Scholz Michael , Schmidt Silke , Loesgen Sabine , Bickeböller Heike
Published: November 2013

Principal component analysis was used to construct quantitative phenotypes for alcoholism. These were analyzed for linkage to genomic regions with a variance components approach. The four phenotypes considered were a factor describing medical symptoms of alcohol dependency, a factor describing a psychological profile correlated with susceptibility to alcoholism, monoamine oxidase B (MAOB) activity and an average measurement of the P3 component of event‐related potentials (ERP) at the Fp electrode placements. One region (around marker GATA123C09 on chromosome 3) with suggestive evidence for linkage was detected for the P3 (Fp) measurement. For three of the four distinct phenotypes, modest evidence for linkage to a similar region (around marker ADH3 on chromosome 4) was found.
Family density of alcoholism and linkage information in the analysis of the COGA data
Authors: Turecki Gustavo , Rouleau Guy A. , Alda Martin
Published: November 2013

In this study of GAW11 Problem 1, we analyzed the genome scan data in families weighted according to the density of alcoholism among the probands' siblings. We hypothesized that certain disease‐predisposing alleles may be common in the general population, rendering high‐density sibships less informative for linkage. Three types of families were found in the data, with the prevalence of alcoholism of 1.0, 0.78, and 0.24 in the probands' sibships. The linkage results showed several peak lod scores on chromosomes 1, 2, 4, 8, 11, 19, and 21, the majority of which originated in only one or two types of families. However, for almost all markers, the maximum lod scores observed without the weights were equal to or exceeded the values obtained for any single type of family. These results indicate that although the stratification of families may be theoretically justified, in practice the best strategy is to use all available information.
Genetic linkage analysis of simulated complex disease data
Authors: Alarcón Maricela , Wang Yaping , Rotter Jerome I. , Yang Huiying
Published: November 2013

The purpose of this analysis was to apply current analytic methods to a simulated data set with a recognized genetic model in order to identify the loci that affect a complex disease, detect evidence for the interaction among two of the loci, and detect the gene‐environment interaction. The following analytic tools were used: two multipoint linkage analysis programs, a stratification strategy based on the results of the multipoint analysis, and a case‐control analysis using discordant sib pair data. The results were consistent with the underlying genetic model: a disease due to a major gene on chromosome 3 associated with an environmental risk factor, and two minor interacting loci on chromosomes 1 and 5.
Complete genomic screen for disease susceptibility loci in nuclear families
Authors: Anderson J.L. , Hauser E.R. , Martin E.R. , Scott W.K. , Ashley‐Koch A. , Kim K.J. , Monks S.A. , Haynes C.S. , Speer M.C. , Pericak‐Vance M.A.
Published: November 2013

We performed genome‐wide model dependent and independent analyses on a simulated data set of 400 families segregating for a rare disorder. Regions on chromosomes 1, 3, and 5 were consistently indicated across the various analyses performed. Follow‐up analyses included stratification for locus heterogeneity and clinical phenotype and studies of gene×gene and gene×environment interaction. The region around D1G024 was most notable, showing strong association and linkage with the trait. We also identified regions D3G043–46 and D5G037–39 by strong linkage and association findings and region D1G001–09 by linkage analysis. A complex statistical interaction was suggested between D1G024, D3G046 and environmental factor 1. This report suggests that traditional methods of analysis can be implemented to analyze and describe the mechanisms that may underlie the more complex genetic disorders.
Strategies for detecting susceptibility genes in a complex disease
Authors: Babron Marie‐Claude , Barillot Emmanuel , Margaritte‐Jeannin Patricia , Clerget‐Darpoux Françoise
Published: November 2013

One of the current issues in genetic epidemiology is detecting susceptibility genes on the genome. It is common now to undertake systematic screening of the genome using approaches based on a measure of the haplotype sharing in sib pairs. Here, we compare the efficiency of two statistics, the maximum likelihood score (MLS) and the nonparametric linkage score (NPLa) on the simulated data provided for GAW11. A question often raised is whether it is better to perform a single‐step or a two‐step strategy. For the simulated model, and whatever the strategy used, we show here that the answer is not unequivocal. In both cases, the power to detect susceptibility genes in a single replicate with MLS or NPL is extremely low. With two replicates, only one of the four simulated loci could be detected with reasonable power. When gametic disequilibrium is suspected, methods testing for both linkage and association might be more powerful.
A simple allele sharing statistic for multiple locus systems
Authors: Barmada M. Michael , Aston Christopher E. , Feingold Eleanor
Published: November 2013

For complex disorders where the actions of several interacting loci must be taken into account, current methods of joint linkage analysis are problematic. We have undertaken an exploration of simultaneous search statistics originally proposed by Dupuis et al. [1995]. Additionally, we have extended these methods slightly and propose here a simple simultaneous search statistic based upon the single‐point allele sharing statistic calculated from GENEHUNTER (GH). The use of conditional search techniques is also explored.
Evaluation of the contribution of environmental factors
Authors: Darlington Gerarda A. , Shin Janey , Paterson Andrew D. , Liu Ying , Fallah Shafagh , Toma Camil
Published: November 2013

For the simulated data of GAW11, the roles of two environmental factors, E1 and E2, were investigated. Logistic regression analyses measuring the association between outcome (either mild or severe disease versus no disease) and E1 and E2 exposure indicated that E1 was a risk factor for disease (either mild or severe) but that E2 was not associated with outcome. Linkage analyses were performed for strata defined by E1 and E2 exposure. A specific disease locus was identified in these stratified analyses where this locus would not have been identified with an unstratified linkage analysis. Finally, stratified generalized transmission disequilibrium test analyses yielded several false positive results.
Search for susceptibility genes, gene×gene interactions, and gene×environment interactions utilizing nonparametric linkage analysis
Authors: Ehm Margaret Gelder , Karnoub Maha Chabhar , Jean Pamela St.
Published: November 2013

There may be a different genetic basis for the two forms of the disease simulated in Problem 2 and the complex disease may be affected by environmental factors. Hence, we investigate the effects of two environmental factors. We selected 400 nuclear families from the data generated for Problem 2. Affection status was investigated in several ways. Individuals with severe and mild forms of the disease were both considered affected, individuals with only the severe form were considered affected while those with the mild form were considered unknown, and individuals with only the mild form were considered affected while those with the severe form were considered unknown. We found evidence of linkage between putative disease loci and markers in the D3G042‐D3G049 and D5G031‐D5G042 regions when we considered severely and mildly affected individuals as affected and also in the region D1G004‐D1G013 when mildly affected individuals were considered unknown. We observed interactions between the first environmental factor and D1G043 among healthy sib pairs.
Detection and modeling of disease susceptibility locus effects: How much can be learned from contrast of populations?
Authors: Génin Emmanuelle , Guyon Frédéric , Margaritte‐Jeannin Patricia , Quesneville Hadi , Clerget‐Darpoux Françoise
Published: November 2013

We report the results of our analyses of the GAW11 Problem 2 data set, using information from three different populations. In the first part of the paper, we used classical population genetic tests to compare affected individuals from the different populations, stratifying on the environmental factors. Thanks to existing linkage disequilibrium in one population, we found one of the disease susceptibility loci. In the second part of the paper, we used the marker association segregation χ2 method to model the role of this disease susceptibility locus in the different populations and draw some inferences regarding the model used at that locus to generate the data.
Meta‐analysis of genetic linkage to quantitative trait loci with study‐specific covariates: A mixed‐effects model
Authors: Gu Chi , Province M. , Rao D.C.
Published: November 2013

A method of meta‐analysis was used to combine summary linkage information from four hypothetical study groups simulated in GAW11 Problem 2 with no knowledge of the answer. Five replication studies were selected from each group, and a pool of 20 primary studies was used for combining. Using a mixed‐effects model with the among‐study variation as random effects, we pooled results from all the 20 studies and detected strong linkage signals on chromosome 5 at D5G38 and on chromosome 3 near D3G45. We also found suggestive signals on chromosome 1 near D1G9, and possible interaction of D1G24 with the selection for the severe form of the disease.
Men with negative results of guaiac‐based fecal occult blood test have higher prevalences of colorectal neoplasms than women with positive results
Authors: Brenner Hermann , Hoffmeister Michael , Birkner Berndt , Stock Christian
Published: November 2013

Guaiac‐based fecal occult blood tests (gFOBTs) are the most commonly applied tests for colorectal cancer screening globally but have relatively poor sensitivity to detect colorectal neoplasms. Men have higher prevalences of colorectal neoplasms than women. In case of a positive gFOBT result, participants are referred to colonoscopy, independent of sex. To assess performance of gFOBT in routine screening practice, we assessed age and sex specific prevalences (age groups: 55–59, 60–64, 65–69 and 70–74) of colorectal neoplasms in 182,956 women and men undergoing colonoscopy for primary screening and in 20,884 women and men undergoing colonoscopy to follow‐up a positive gFOBT in Bavaria, Germany, in 2007–2009. We conducted model calculations to estimate prevalences among gFOBT negative individuals. Analogous model calculations were performed for women and men tested positive or negative with fecal immunochemical tests. In all age groups (55–59, 60–64, 65–69 and 70–74 years), men undergoing colonoscopy for primary screening had substantially higher prevalences of any colorectal neoplasms and essentially the same prevalences of advanced colorectal neoplasms compared to women undergoing colonoscopy to follow‐up a positive gFOBT. Model calculations suggest that men with negative gFOBT likewise have substantially higher prevalences of colorectal neoplasms than gFOBT positive women in each age group. Model calculations further indicate that no such sex paradoxon occurs, and a much clearer risk stratification can be achieved with fecal immunochemical tests. Our findings underline need to move forward from and overcome shortcomings of gFOBT‐based colorectal cancer screening.
Phosphate and Silica Adsorption and Desorption from Soils
Authors: Kafkafi U. , Giskin M. , Hagin J.
Published: November 2013

Phosphate adsorption and desorption in conjunction with silica desorption, were studied on soils of two field experiments. The soil samples were taken from control plots and plots that had received a total of 14 ton/ha superphosphate over a three‐year period. Initially, silica desorption was increased by P added in the past as fertilizer and that added in equilibration solutions. Subsequently, after repeated washings, the rate of silica desorption was independent of the previous phosphate treatment. The adsorbed P was completely leached from the high P fertilized samples but not from those of the control. The slow reaction of phosphate with the soil was accompanied by a release of silica to the equilibrium solution. Most of the slow reaction product was not isotopically exchangeable in 48 hr.
Weathering Products of Basalt in the Galilee. I. Rock‐Soil Interface Weathering
Authors: Singer A.
Published: November 2013

The most common weathering form of the cover basalt in the Galilee is a thin weathering crust characterized by a sharp concentration change of some of the chemical constituents across the rock‐soil interface. Large losses of Mg, Ca, Na, K and smaller ones of Si have occurred in the clay fraction of the crust and are accompanied by the nearly complete disappearance of mafic minerals. Plagioclase persists in part in the clay fraction of the crust indicating a greater stability of this mineral. Clay minerals formed in the course of the weathering include smectite, halloysite and kaolinite. The chemical and mineralogical transitions across the sharply defined weathering front are associated with changes in the pH environment of the unaltered rock, of the crust and of the soil.
The Structure of N‐(Alkoxycarbonyl)Guanidines
Authors: Hoffmann E. , Laub C.
Published: November 2013

A number of N‐(alkoxycarbonyl)guanidines have been synthesized and their IR spectra determined. These spectra show the compounds to exist in the acylimino form. The corresponding UV and NMR spectra—though not conclusive by themselves — are in agreement with this result.
Direct Selective Tosylation of Some Pentosides
Authors: Friedman Noga , Cohen S. , Bergmann E.D.
Published: November 2013

Direct selective tosylation of benzyl α‐D‐xylopyranoside leads first to the 3‐O‐tosyl, then to the 2,3‐di‐O‐tosyl derivative. The same procedure applied to benzyl β‐D‐arabinopyranoside leads first to the 2‐O‐tosyl then to the 2,3‐di‐O‐tosyl derivatives. The ease of preparation and separation of these products offers a definite advantage over indirect methods that rely on the use of temporary masking groups.
Attempted Skeletal Rearrangements in the Lanostane Series
Authors: Levy E. C. , Lavie D.
Published: November 2013

The conversion of a lanostane skeleton into a cucurbitane (C‐9β‐Me) has been explored. Several derivatives with an oxirane ring in the appropriate location to induce a methyl migration (while having an adjacent oxygen function as required in the cucurbitacins) have been treated with SnCl4. The reaction took however, a different course and the products have been analysed and identified. During treatment with SnCl4 of the epoxy‐lanostane derivative having a diosphenol system in ring A, an acid stable organo‐tin complex was observed to be formed. Base hydrolysis of this complex produced compounds similar to those obtained in the previous examples.
Ozonide and Hydroperoxy Radicals in Flash Photolysis of Hydrogenperoxide
Authors: Behar D. , Czapski G.
Published: November 2013

The properties of ozonide and hydroperoxy radicals were studied in the flash photolysis of H2O2. Evidence for the reaction magnified image was found. The spectrum of O−2 is given with λmax = 240 nm and ϵ340 = 1900 ± 100 M−1 cm−1. No evidence was found for the existence of H2O+2. The recombination kinetics of the hydroperoxy radical are discussed. It was shown that O−3 has no absorption in the UV. The reaction of O−3 with H2O2 was shown to proceed via dissociation of O−3 into O−, and the product of the reaction was identified as O−2. No ozone is found in the decay of O−3.
Synthetic Peptides Related to Horse Heart Cytochrome C VI. Peptides Corresponding to Positions 85–104
Authors: Wolman Y. , Klausner Y. S.
Published: November 2013

Synthesis is described of an eicosapeptide which corresponds to positions 85‐104 of the primary structure of horse heart Cytochrome C. The synthesis of the peptide L‐isoleucyl‐L‐lysyl‐L‐lysyl‐L‐lysyl‐L‐threonyl‐L‐glutamyl‐L‐arginyl‐L‐glutamyl‐L‐aspartyl‐L‐leucyl‐L‐isoleucyl‐L‐alanyl‐L‐tyrosyl‐L‐leucyl‐L‐lysyl‐L‐lysyl‐L‐alanyl‐L‐threonyl‐L‐asparaginyl‐L‐glutamic acid is described.
Kinetic Salt Effects and Structure of the Aqueous Solution
Authors: Indelli A.
Published: November 2013

The salt effects in many reactions between anions are compared with the predictions of the Brønsted‐Debye theory, and with the assumption of formation of reactive ion pairs; both approaches appear to be inadequate. Clear evidence is available (change of activation energy, effect of organic ions, effect of complex ions) that at least part of the salt effects is non‐electrostatic in nature, so that the introduction of appropriate structural parameters in a general electrostatic treatment is required for their explanation. The Debye‐Hückel theory cannot be used as a frame for the introduction of such parameters, but a more flexible and self‐consistent theory is required. Evidence is presented that the Mayer theory can interpret thermodynamic properties even in cases where the Debye‐Hückel theory fails, and a method is suggested whereby the Mayer theory is used to interpret the salt effect and to give a structural meaning to the empirical parameters which must be introduced.
Decomposition of H2O2 by Iron Centered Catalysts
Authors: Kremer M.L.
Published: November 2013

The kinetics and mechanism of the catalytic decomposition of H2O2 by Fe3+ ion, haemin and catalase are discussed. A general mechanism is set up. The kinetic features of the three catalytic systems are discussed in terms of this mechanism.
Potential Practical Applications of Basic Research in Molecular Dynamics
Authors: Bernstein R.B.
Published: November 2013

The chemical technology of the future will require a deeper knowledge of fundamental molecular‐dynamical processes. It will no longer suffice to be able to systematize (and even calculate) static properties of simple molecules in equilibrium or to produce tables of Arrhenius kinetic parameters characterizing the rate constants of a host of elementary chemical reactions. In order to make significant gains, in the sense of “breakthrough technology”, an intimate knowledge of basic molecular dynamical behavior will be needed. Such insight is derivable from a new class of experiments at the atomic and molecular level and from new theoretical‐computational approaches to molecular‐dynamical problems. To illustrate these new requirements, and the potential practical applications of an improved understanding at the basic level, examples are presented in the areas of combustion and atmospheric pollution, atmospheric and ionospheric chemistry, synthetic applications of selective excitation, lasers in chemistry and chemical‐to‐radiation energy conversion.
Ionization Processes in Polar Solution of Tryptophan at 77° K
Authors: Moan J.
Published: November 2013

The triplet absorption spectrum of tryptophan in ethylene‐glycol/water glass at 77°K has been registered. It is demonstrated that light of wavelength 250 nm produces trapped electrons by a two‐photon process in this system. In both UV‐ and X‐ray‐induced ionization the probability that an ejected electron will recombine with its mother ion is around 0.5. Bleaching with visible light causes the trapped electrons to react with the solvent and there is also a considerable degree of retrapping. The retrapping becomes more probable when the temperature increases.
The Potassium Permanganate Oxidation of Methylated and Unmethylated Humic Acids Extracted from Solonetz, Solod and Chernozem Ah Horizons
Authors: Khan S.U. , Schnitzer M.
Published: November 2013

Humic acids were extracted from Ah horizons of a Solonetz, a Solod, and a Chernozem soil. A portion of each extracted humic acid was methylated in order to make it more resistant to attack by electrophilic KMnO4. Both the methylated and unmethylated humic acids were then oxidized with KMnO4. The oxidation products were extracted into ethyl acetate and separated by preparative gas chromatography into relatively pure components, which were then analyzed by mass spectrometry and micro‐infrared spectrophotometry. A matching of the mass and IR spectra and gas chromatographic retention times of the isolated components with those of authentic specimens led to their identification.

The most prominent compounds produced by the oxidation of methylated humic acids were 1,3,5‐benzenetricarboxylic acid and a complex phenolic acid, tentatively identified as propanone‐hydroxy‐methyl acetoxy‐benzene‐dicarboxylic acid. These two compounds accounted for between 18 and 23% of the original methylated humic acids. The main products resulting from the oxidation of unmethylated humic acids were benzenetri‐, benzenetetra‐ and benzenepenta‐carboxylic acids, which constituted between 10 and 12% of the weights of the original unmethylated humic acids. The results show that methylation of humic acids prior to oxidation is a useful procedure which substantially increases the yields and types of oxidation products. From the similarities in analytical data and in the quality of the oxidation products, we conclude that the three humic acids have similar chemical structures, yielding benzenecarboxylic and phenolic acids on oxidation. These compounds either originate from more complex structures or they exist in the humic acids in the forms in which they were isolated, held together by hydrogen bonds.
The Molecular and Crystal Structure of Photochemically Formed 1‐H1 : 1,2‐H2‐Trans‐2‐Bromovinyl‐μ‐Bromobis(Tricarbonyliron) (Fe‐Fe) A Carbonyliron‐π‐Complex of the 1‐Ferra‐Allylic System
Authors: Krüger C. , Tsay Y. H. , Grevels F. W. , Von Gustorf E. Koerner
Published: November 2013

The molecular structure of 1‐h1: 1,2‐h2‐trans‐2‐bromovinyl‐μ‐bromo‐bis(tricarbonyliron) (Fe‐Fe), Fe2Br2C8O6H2, has been determined from 1970 absorption‐corrected diffractometer intensity data by Patterson and Fourier methods and refined anisotropically by least‐squares methods to a final R‐value of 6.07%, including anomalous‐dispersion corrections. The molecular framework consists of two distorted octahedral Fe(CO)3 moieties linked together by a slightly asymmetric bromine bridge, an Fe‐Fe bridge (2.525 Å) and a π‐bonded bromovinyl group. The bonding features of the organic ligand suggest the formation of a 1‐ferra‐π‐allyl system. Within the irontricarbonyl fragments, strong trans effects are observed. Cell data are: a = 9.373(4) b = 23.716(12) c = 6.671(4) Å β= 113.96(4)°, Z = 4. Space group Cc (No. 9). A mechanism for the formation of the compound is suggested.
Relative Dipole Moments of Excited Singlet and Triplet States in Molecules
Authors: Coulson C. A.
Published: November 2013

The availability of experimental values of molecular dipole moments in electronically excited states suggests the desirability of establishing some general principles. Three such principles are proposed, as a means of explaining the observed values of the dipole moment in corresponding singlet and triplet states, where the relevant molecular orbitals are very similar. The general conclusion is that we shall usually expect μGS ‐ μT to be larger than μGS ‐ μS, where μGS, μT, μS are the dipole moments in the ground state, the excited triplet and singlet states respectively. The principles are illustrated by specific reference to NF, CO, BeO, formaldehyde, methylene and azulene. Some difficulties arise with larger molecules, and also when configuration interaction plays an unusually important rǒle.
Thione Photochemistry: On Thiobenzophenone Photoannelation
Authors: De Mayo P. , Nicholson A. A.
Published: November 2013

The photochemistry of the reaction of thiobenzophenone with acrylonitrile, following excitation into both the n, π* and π, π* absorption bands, has been examined. The products obtained are different, indicating dual mechanisms. It has been shown that the thietane is not a primary product, but is the result of thermal decomposition of a 1,3‐dithiane which can be isolated at low temperatures. This is the main product at the shorter wavelengths, but at longer wavelengths a 1,4‐dithiane and a thiatetrahydronaphthalene are obtained. A disulphide is also produced as a result of a secondary photochemical attack of thiobenzophenone on the thietane. The mechanistic implications of these results are discussed.
Preliminary Experiments on Solid/Gas Reactions by the Fluidized Bed Method; Preparation of 1,4‐Dicyanobuta‐1,3‐Diene from 2,3‐Dibromo‐1,4‐Dicyanobutane
Authors: Friedman G. , Cohen C. , Wolf D. , Schmidt G. M. J.
Published: November 2013

Preliminary experiments on the fluidized bed reaction of gaseous ammonia with solid 2,3‐dibromo‐1,4‐dicyanobutane to yield 1,4‐dicyanobuta‐1,3‐diene are described.
The Thermal Reaction of Substituted Vinylcyclopropanes with Iron Pentacarbonyl
Authors: Sarel S. , Ben‐Shoshan R. , Kirson B.
Published: November 2013

The thermal reactions of 1‐aryl‐1‐cyclopropylethylenes and 1,1‐dicyclopropylethylene with pentacarbonyliron are investigated. Reactions of the former substrates yield 2‐aryl‐1,3‐pentadiene‐tricarbonyliron complexes via cyclopropane ring opening, hydrogen migration and coordination to iron. Reaction with the latter substrate gives 2‐cyclopropyl‐1,3‐pentadienetricarbonyliron in similar fashion, and, in addition, 3‐(1′‐propenyl)‐cyclohex‐2‐enone tricarbonyliron derived from the opening of the second ring coupled with carbon monoxide insertion. The cyclopropane ring serves as a two π‐electron donor in these reactions, and the vinylcyclopropane system emerges as a novel source of four π‐electrons which are available to coordination in direct analogy to reactions of formal diene systems with iron carbonyls.
The Reduction of Ferricytochrome c Studied by Pulse Radiolysis
Authors: Nilsson Karen
Published: November 2013

The formation of ferrocytochrome c upon pulse radiolysis of aqueous solutions of ferricytochrome c has been studied by following spectral shifts at 550 nm and 700 nm. The reaction between ferricytochrome c and hydrated electrons was studied by following the decay of hydrated electrons as well as the ferrocytochrome c formation. The two processes proceed with the same rate which indicate diffusion‐controlled processes with a second order rate constant of 1.1 × 1011 M−1 sec−1. The reaction between ferricytochrome c and H atoms was studied in a system containing H atoms only and found to be a second order reaction with a rate constant of 1.5 × 1010 M−1 sec−1. The formation of ferrocytochrome c by reaction between ferricytochrome c and OH radicals proceed by a first step with a second order rate constant of 1.4 × 1010 M−1 sec−1 during which OH radicals react with the protein part of ferricytochrome c forming an organic radical. Some of these radicals then undergo intramolecular reduction with a rate constant of 3.1 × 103 sec−1.
Mechanisms of Radiation‐Induced Strand Break Formation in DNA
Authors: Ward J. F.
Published: November 2013

The mechanisms by which γ‐radiation produces strand breaks in DNA were investigated using model systems: breakage of the sugar phosphate bond of deoxynucleotides irradiated in aqueous solution was equated to a reaction which would produce a strand break in DNA. Release of inorganic phosphate from 5′ deoxynucleotides is caused by a radiation‐produced hydroxyl radical abstracting a hydrogen atom from the deoxyribose moiety. Decay of the sugar radical so formed leads to phosphate release. After release of inorganic phosphate from deoxycytidylic acid two products are formed which consist of the cytosine base moiety attached to two or three carbon atoms of the sugar. Radioprotective sulphydryl compounds can repair the sugar radical by donation of a hydrogen atom to the damaged site. In thymidine 3′5′ diphosphate, reaction of OH* radicals with the base moiety as well as with the sugar can lead to inorganic phosphate release, both reactions leading to breakage of both 3′ and 5′ sugar phosphate bonds in the same molecule. When thymidine 3′5′ diphosphate is irradiated in the presence of oxygen, labile phosphate esters are produced in yields which are large compared to the inorganic phosphate yield. Reaction of 5‐bromouracil moieties in DNA with hydrated electrons can also lead to strand break production. Transfer of the electron to 5‐bromouracil from the thymine anion radical was found to be an efficient reaction. Other species such as HCO2−, O2−, and the cytosine anion radical can also donate electrons to 5‐bromouracil. The results and conclusions of these experiments are discussed with reference to reactions which could occur in DNA.
Mechanism of Sensitization to UV Radiation by 5‐Br‐Uracil Substituted DNA
Authors: Lion M.
Published: November 2013

DNA, in which thymine is substituted by 5‐bromouracil is sensitized to the effect of ultraviolet light. Various chemical changes produced in the DNA are described. These include single and double strand breaks, base loss, protein DNA crosslinks as well as the influence of the three dimensional structure of DNA on some of these changes.
The Hydrated Electron, The Hydroxyl Radical, and Hydrogen Peroxide in Radiation Damage in Cells
Authors: Powers E. L.
Published: November 2013

Spores of Bacillus megaterium, in suspension, are used to study the biological effects of the three principal products of radiolysis of water, i.e., e−aq, OH and H2 O2. A model is proposed accounting for the action of OH and H2 O2. This model involves two reactions:

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in which RH2 is a “target” molecule, and \documentclass{article}\pagestyle{empty}\begin{document}$ \[ \underline {\rm R} \] $\end{document} is a lethally damaged molecule. Experimental evidence is given supporting this model. These studies of the effects of radiolysis products of water are extended by studies using sensitizers such as biacetyl, NO−3, and Ag+ in varying concentrations. Evidence for a possible relationship between peak sensitivities in anoxic conditions and chemical properties of the sensitizers is discussed. These results are also discussed with regard to the oxygen effect, and the general chemical characteristics of an efficient tumor sensitizer are outlined.
Mechanism of Phage Inactivation by Radiation
Authors: Dewey D. L.
Published: November 2013

Bacteriophage show two completely different types of response to radiation depending on whether they are irradiated in dilute aqueous solution, where the major lethal event is due to external radicals formed in the water, or whether they are irradiated in nutrient broth or some other radical scavenging medium; under these protected conditions a major lethal event is double strand breaks in the DNA. Single strand breaks do not appear to matter but the contribution of base damage has not yet been directly measured. In dilute solution the most effective radical for phage inactivation is the hydrogen atom followed by the OH radical and the hydrated electron, in that order. The mechanism of inactivation appears to be a radical attack on the phage tail causing a premature release of the DNA from the phage head. It is suggested that the energy for DNA release is stored in the tail and that the hydrogen atom triggers the release of this energy.
A Conductometric Study of Complexation of Macrocyclic Polyethers with Sodium Salts
Authors: Shchori E. , Jagur‐Grodzinski J.
Published: November 2013

The complexation of sodium ions with the macrocyclic polyethers dibenzo‐18‐crown‐6 (DBC), cis‐4,4′‐dinitro‐dibenzo‐18‐crown‐6 (NDBC) and cis‐4,4′‐diamino‐dibenzo‐18‐crown‐6 (AmDBC) has been investigated conductometrically in the temperature range 10–40°C. A computer program based on iteration procedure has been used for the calculation of the equilibrium constants. In DMF, KNDBC < KDBC ≅ KAmDBC (at 30°, KNDBC = 100 M−1, KAmDBC = 580M−1). In dimethoxyethane (DME), values of K's for the complexation of DBC with free sodium ions and with the sodium tetraphenylboron ion pairs have been shown to be nearly identical (at 30° Kf = 4.5 × 103M−1, Kip = 4.2 × 103M−1). The complexation reaction in DME is both entropy and enthalpy driven. Fuoss plots has been used in the calculations of the dissociation constants of the complexed and of the solvated sodium tetraphenylboron in DME at 10–40°C. The apparent ionic radius of the sodium ion complexed with DBC has been found to be about 4.5Å. A significant contribution of the DME molecules to the solvation of sodium ions complexed with DBC seem to be ruled out on the basis of the analysis of the thermodynamic parameters of the system.