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PubMed1996

Novel alleles HLA-B*7802 and B*51022: evidence for convergency in the HLA-B5 family.

We have characterized two novel HLA-B alleles, B*7802 and B*51022. The Caucasian-derived variant B*7802 most resembles the African-derived variant B*7801, from which B*7802 differs by two nucleotides. Only one of these modifications, however, is translated: a tyrosine for aspartate substitution occurs at residue 74 in B*7802, while the second nucleotide difference reflects a proximal synonymous substitution in codon 23. A second variant, B*51022, differs synonymously only at codon 23 from B*51021. Comparative analysis of the B5 CREG demonstrates that other pairs of B5 alleles differ synonymously only at codon 23 or synonymously at codon 23 and non-synonymously at a second more distal location. Contrary to the genesis of like pairs of B5 alleles via introduction of coordinate yet distant mutagenic events onto a single B5 progenitor, we postulate that synonymously different B5 progenitor molecules, B5ATT and B5ATC, are evolving in convergence to generate homologous B5 allele pairs differing silently at codon 23. Our finding that B*7802 is a single amino acid away from complete convergence with B*7801 and that B*51022 and B*51021 are in complete convergence is exemplary of such evolution.

Alleles↗
PubMed1997

Analysis of VH gene diversity in rainbow trout (Oncorhynchus mykiss): both nonsynonymous and synonymous nucleotide changes are more frequent in CDRs than in FRs.

Forty-six immunoglobulin VH gene sequences of rainbow trout were compiled to analyze the extent of variations and the frequency of nucleotide changes in CDRs and FRs. The results show that the frequency of nonsynonymous (amino acid replacing) changes (Ka) are on average 4.9 times higher in complementarity determining regions (CDRs) than in FRs, thus contributing more diversity in CDRs. Unexpectedly, however, the frequency of synonymous (silent) changes (Ks) show the same tendency: it was 5.3 times higher in CDRs than in framework regions (FRs). The distribution of Ks/Ka ratios of each comparison shows no segregation between CDRs and FRs. The same analysis applied to five germline VH genes of Heterodontus francisci shows the same result as was found with the rainbow trout. In contrast, the results from mouse data show that, while the CDR/FR ratio for Ka is much higher (7.4), the CDR/FR ratio for Ks is only slightly higher (1.8). The distribution of Ks/Ka ratios in mouse indicates clear segregation between CDRs and FRs. This suggests that CDR germline diversity is largely generated by gene conversion in VHs of lower vertebrates such as rainbow trout or shark. This mechanism might be advantageous to lower vertebrates in generating V gene diversity faster than other mechanisms such as point mutation and selection.

Animals↗
PubMed2006

Expression and diversity of Echinococcus multilocularis AgB genes in secondarily infected mice: evaluating the influence of T-cell immune selection on antigenic variation.

The T-cell-mediated immune response exhibits a crucial function in the control of the intrahepatic proliferation of Echinococcus multilocularis larvae in mice and humans, both being natural intermediate hosts of the parasite. Antigen B (AgB), a metabolized Echinococcus spp. lipoprotein, contributes to the modulation of the T-cell immune response, and distinct sites of the corresponding AgB1, AgB3 and AgB4 genes were shown to be under positive selection pressure. Since several AgB gene variants are present in a single Echinococcus metacestode, we used secondary E. multilocularis infections in BALB/c and in athymic nude mice (devoid of T-cell responses) to analyze the effect of the cellular immune response on the expression and diversity of EmAgB1-EmAgB4 genes. We demonstrated hereby that EmAgB transcripts were less abundant in nude mice during the early phase of infection (at one month post-infection), and that EmAgB2 is simultaneously down-regulated when compared to the other three genes. A negative relationship exists between the level of transcription and diversity of EmAgB genes. Moreover, no excess of non-synonymous substitutions was found among the distinct EmAgB alleles from a single host. Together, these results pointed to the effect of purifying selection, which seemed to eliminate the detrimental AgB variants generated during the development of the metacestode within the peritoneal cavity of its intermediate host.

Animals↗
PubMed2004

Analysis of factors shaping codon usage in the mitochondrion genome of Oryza sativa.

In this paper, the main factors shaping codon usage in the mitochondrion genome of rice were reported. Correspondence analysis, a commonly used multivariate statistical approach, was carried out to analyze synonymous codon usage bias. The results showed that the main trend was strongly correlated with the gene expression level assessed by the 'Codon Adaptation Index' value, a result that was confirmed by the distribution of genes along the first axis. From the results that there were two significant correlations between axis 1 coordinates and the GC, GC3s content at silent sites of each sequence, and clearly significant correlations between the 'Effective Number of Codons' values and GC, GC3s content, we inferred that codon usage bias was affected by gene nucleotide composition also. In addition, the hydrophobicity of each protein also played some roles in shaping codon usage in this organelle, which could be confirmed by the significant correlation between the positions of genes placed on the first axis and the hydrophobicity value of each protein. In summary, natural selection played a crucial role, nucleotide mutational bias and amino acid composition only in a minor way, in shaping codon usage in the mitochondrion genome of rice. Notably, 21 codons defined firstly as 'optimal codons' might provide some more useful information for gene engineering and/or evolution studying.

Journal Article↗
PubMed1994

Codon usage and bias among individual genes of the coccidia and piroplasms.

Codon usage has been analysed in individual gene sequences, derived from a variety of parasitic protozoa in the class Sporozoa of the phylum Apicomplexa using metric multidimensional scaling. The two groups of codon usage patterns detected reflect the two main subgroups of organisms studied (the coccidia and the piroplasms), and it is the pattern of usage of synonymous codons that has the largest influence on overall codon usage in the individual genes, rather than being the pattern of amino acid composition of the gene product. The magnitude of the codon usage bias in the sequences was determined using three commonly used indices-NC, GC3S and B. In general, although relatively low levels of codon usage bias were detected in these gene sequences, codon usage bias does explain at least some of the codon usage patterns observed. Codon usage bias was observed to be dependent on the overall base composition of the genes analysed, which in turn was reflected in the types of codons that were either over- or under-represented in the nucleotide sequences. In keeping with observations on prokaryotic organisms, it is speculated that the codon usage patterns detected in these parasitic protozoa are the result of directional mutation pressure on the base composition of the genomic DNA.

Animals↗
PubMed1985

NTP Toxicology and Carcinogenesis Studies of Diallylphthalate (CAS No. 131-17-9) in F344/N Rats (Gavage Studies).

Diallylphthalate is widely used as a crosslinking agent for unsaturated polyesters. Diallylphthalate or diallylphthalate polyester blends are used primarily as plasticizers and carriers for adding catalysts and pigments to polyesters and in molding, electrical parts, laminating compounds, and impregnation of metal castings. Rubber compounds, epoxy formulations, and polyurethane foams may also contain diallylphthalate. Precise figures are not currently available, although annual production of diallylphthalate in the United States is known to exceed 5,000 pounds, and an estimated 57,000 pounds were imported into the United States in 1982. Toxicology and carcinogenesis studies of diallylphthalate (approximately 99% pure) were conducted by administering the test chemical in corn oil by gavage to groups of 50 male and 50 female F344/N rats at doses of 0 (vehicle control), 50, or 100 mg/kg 5 days per week for 103 weeks. The diallylphthalate doses used in the 2-year studies were chosen on the basis of 13-week studies, wherein doses of 200 or 400 mg/kg caused death, reductions in body weight gains, or periportal hepatocellular necrosis and fibrosis in both sexes. Mean body weights and survival of male and female rats administered diallylphthalate were essentially the same as those of the vehicle controls throughout the 2-year studies, although hepatotoxicity was produced in both sexes by the 100 mg/kg dose. Based on the results of the prechronic studies and the effects on the liver in the 2-year studies, the doses used in the 2-year studies were considered to be adequate for carcinogenicity testing. Male and female rats receiving the 100 mg/kg dose of diallylphthalate in the 2-year studies developed chronic liver diseases characterized by periportal fibrosis, periportal accumulation of pigment, and severe bile duct hyperplasia. Pigment accumulation also occurred at the 50 mg/kg dose in both sexes. Diallylphthalate administration increased the occurrence of mononuclear cell leukemia in female rats (P<0.05 by trend tests), and the increase in the 100 mg/kg dose female rats was greater (P</=0.05) than in the vehicle controls by pairwise comparisons (vehicle control, 15/50, 30%; low dose, 15/43, 35%; high dose, 25/49, 51%). An increased occurrence of mononuclear cell leukemia was not observed in male rats receiving diallylphthalate. A previous NTP carcinogenesis study (NTP TR 242) reported an increased incidence of lymphomas in male B6C3F1 mice receiving diallylphthalate by gavage for 2 years at doses of 0, 150, or 300 mg/kg. This increase was considered to be equivocally related to diallylphthalate administration. The incidences of hyperplasia and inflammatory lesions of the forestomach were increased in a dose-related fashion in both sexes of mice in that study, and uncommon forestomach papillomas were observed in 0%, 2%, and 4% of both sexes of mice. Because of the numerical increase in forestomach papillomas, the concomitant presence of forestomach hyperplasia, and the rarity of forestomach papillomas in vehicle control (corn oil gavage) B6C3F1 mice, the development of these proliferative lesions of the forestomach in mice may have been related to diallylphthalate administration. In the current study in rats, a squamous cell carcinoma was found in one high dose male rat. Diallylphthalate was not mutagenic in Salmonella typhimurium strains TA98, TA100, TA1535, or TA1537 with or without activation by a 9,000 x g supernatant fraction from the livers of Aroclor 1254-treated male Sprague-Dawley rats or Syrian hamsters. Diallylphthalate did not induce sex-linked recessive lethal mutations in Drosophila melanogaster. An audit of the experimental data was conducted for these carcinogenicity studies on diallylphthalate. No data discrepancies were found that influenced the final interpretations. Under the conditions of this study, the administration of diallylphthalate by gavage in corn oil to male and female F344/N rats for 2 years caused chronic liver disease characterized by periportal fibrosis and pigment accumulation and an increasetal fibrosis and pigment accumulation and an increased severity of bile duct hyperplasia. The incidence of mononuclear cell leukemia was significantly increased in female rats receiving 100 mg/kg. Because of the variability in the incidence of this neoplasm in aged Fisher 344 rats and the difficulty in definitively diagnosing this lesion in Fisher 344 rats, this increase was considered to be equivocal evidence of carcinogenicity of diallylphthalate in female rats. There was no evidence of carcinogenicity in male rats. Synonym: DAP

Journal Article↗
PubMed2006

Analysis of codon usage pattern in the radioresistant bacterium Deinococcus radiodurans.

The main factors shaping codon usage bias in the Deinococcus radiodurans genome were reported. Correspondence analysis (COA) was carried out to analyze synonymous codon usage bias. The results showed that the main trend was strongly correlated with gene expression level assessed by the "Codon Adaptation Index" (CAI) values, a result that was confirmed by the distribution of genes along the first axis. The results of correlation analysis, variance analysis and neutrality plot indicated that gene nucleotide composition was clearly contributed to codon bias. CDS length was also key factor in dictating codon usage variation. A general tendency of more biased codon usage of genes with longer CDS length to higher expression level was found. Further, the hydrophobicity of each protein also played a role in shaping codon usage in this organism, which could be confirmed by the significant correlation between the positions of genes placed on the first axis and the hydrophobicity values (r=-0.100, P<0.01). In summary, gene expression level played a crucial role, nucleotide mutational bias, CDS length and the hydrophobicity of each protein just in a minor way in shaping the codon usage pattern of D. radiodurans. Notably, 19 codons firstly defined as "optimal codons" may provide useful clues for molecular genetic engineering and evolutionary studying.

Codon↗
PubMed2005

Clinical aspects of hemochromatosis.

The term hemochromatosis is commonly used as synonymous with HFE-associated genetic iron overload but several rarer causes of an identical clinicopathological syndrome have been described in recent years. The most common symptoms are lethargy and arthralgia, and the major complications of end-stage disease are cirrhosis, diabetes, and cardiac and endocrine manifestations. However, with the development of cascade screening for family members of affected probands as well as screening for common diseases at health checks, hemochromatosis is being detected at increasingly early stages, often when there are only biochemical abnormalities. The available evidence from screening studies strongly suggests that approximately 75% of C282Y homozygous subjects have biochemical expression. Hepatic iron overload is present in approximately 56% and 34% of men and women, respectively, advanced hepatic fibrosis in 18.7% and 5.4%, respectively, and cirrhosis in 5.8% and 1.9%, respectively. In subjects with severe expression of the disease, additional modifying genetic mutations have been described including those in hepcidin and hemojuvelin. Treatment is by regular phlebotomy which, if instituted before the development of cirrhosis, results in normal life expectancy.

Genetic Predisposition to Disease↗
PubMed1999

NTP Toxicology and Carcinogenesis Studies of Isobutyraldehyde (CAS No. 78-84-2) in F344/N Rats and B6C3F1 Mice (Inhalation Studies).

Isobutyraldehyde, a branched alkyl aldehyde, is used as a chemical intermediate and flavoring agent. It was nominated by the National Cancer Institute for toxicity and carcinogenicity studies by the NTP. Reasons for nomination and selection of isobutyraldehyde for study included its high potential for human exposure as suggested by its high production volume, its use as a chemical intermediate and food flavoring agent, suspicion of carcinogenicity due to an increased incidence of cancer at an aldehyde manufacturing plant where workers were exposed to a variety of aldehydes, its structural relationship to formaldehyde (a nasal carcinogen in rats), and the lack of toxicity and carcinogenicity studies on isobutyraldehyde in animals. Although human exposure occurs orally, dermally, or via inhalation, the inhalation route of exposure was selected for these animal studies because of the instability of isobutyraldehyde in water and feed. Male and female F344/N rats and B6C3F1 mice were exposed to isobutyraldehyde (approximately 99% pure) by inhalation for 13 weeks or 2 years. Genetic toxicology studies were conducted in vitro in Salmonella typhimurium, L5178Y mouse lymphoma cells, and cultured Chinese hamster ovary cells; in vivo tests were conducted in Drosophila melanogaster germ cells and bone marrow cells of rats and mice. 13-WEEK STUDY IN RATS: Groups of 10 male and 10 female F344/N rats were exposed to 0, 500, 1,000, 2,000, 4,000, or 8,000 ppm isobutyraldehyde by inhalation, 6 hours per day, 5 days a week, for 13 weeks. All rats exposed to 8,000 ppm died before the end of the study. Three male rats and six female rats in the 4,000 ppm groups and one female in the 500 ppm group died before the end of the study. The final mean body weight of male rats in the 4,000 ppm group and the body weight gains of 4,000 ppm males and females were significantly less than those of the chamber controls. Clinical findings in rats exposed to 4,000 or 8,000 ppm included abnormal respiratory sounds, decreased activity, nasal discharge, prostration, and slowed respiration. A minimal mature neutrophilia, evidenced by increased segmented neutrophil numbers, occurred in exposed groups of male and female rats. Exposure to isobutyraldehyde resulted in minimal increases in alanine aminotransferase activity in all groups of male and female rats. Spermatozoal motility in 500 and 1,000 ppm males was significantly reduced and females exposed to 4,000 ppm differed significantly from the chamber control females in the relative time spent in the estrous stages. No gross lesions were observed at necropsy that could be associated with isobutyraldehyde exposure. In the 8,000 ppm groups, severe necrosis of the epithelium, and occasionally of the entire mucosa, of the nasal turbinates accompanied by an acute inflammatory reaction was observed. Increased incidences of squamous metaplasia and mild acute inflammation occurred in male and female rats exposed to 4,000 ppm. Minimal to mild degeneration of the olfactory epithelium was observed in all male rats in the 2,000 and 4,000 ppm groups. Male rats exposed to 4,000 or 8,000 ppm and females exposed to 4,000 ppm had mild osteodystrophy of the turbinate bone. The incidences of necrosis/degeneration of the larynx and trachea were increased in male rats in the 8,000 ppm group. The incidences of mild to moderate lymphoid depletion of the spleen and thymus and lymphoid necrosis of the thymus were significantly increased in male and female rats exposed to 8,000 ppm. 13-WEEK STUDY IN MICE: Ten male and 10 female B6C3F1 mice were exposed to 0, 500, 1,000, 2,000, 4,000, or 8,000 ppm isobutyraldehyde by inhalation, 6 hours per day, 5 days per week, for 13 weeks. One male in the chamber control group, one male in the 1,000 ppm group, nine males and all females in the 4,000 ppm groups, and all males and females in the 8,000 ppm groups died before the end of the study. The final mean body weight and body weight gain of female mice in the 1,000 ppm group were significantly less than those of the chamber controls. Clinical findal findings included decreased activity, tremors, prostration, and slower and labored respiration. The absolute and relative kidney weights of males in the 1,000 and 2,000 ppm groups were significantly increased. There were no gross lesions observed at necropsy that could be associated with isobutyraldehyde exposure. Histopathologically, the nasal cavity and lymphopoietic tissues were considered target organs, with changes similar, but not identical, to those observed in rats. Increased incidences of nonneoplastic lesions of the nasal cavity were observed in male and female mice exposed to 1,000 ppm or greater. These lesions included necrosis, inflammation, hyperplasia, and squamous metaplasia of the epithelium; serous and suppurative exudate within the nasal passages; olfactory epithelial degeneration; and osteodystrophy of the turbinate bone. Mild to moderate lymphoid depletion and/or lymphoid necrosis were observed in the thymus of male and female mice exposed to 8,000 ppm. 2-YEAR STUDY IN RATS: Groups of 50 male and 50 female F344/N rats were exposed to 0, 500, 1,000, or 2,000 ppm isobutyraldehyde by inhalation, 6 hours per day, 5 days per week, for 105 weeks Survival, Body Weights, and Clinical Findings No differences in survival rates between exposed and chamber control rats were found. The mean body weights of male and female rats were generally similar to those of the chamber controls throughout the study. Pathology Findings No increase in neoplasm incidences that could be attributed to exposure to isobutyraldehyde was observed in male or female rats. Nonneoplastic lesions related to isobutyraldehyde exposure were limited to the nose and consisted of squamous metaplasia of the respiratory epithelium, degeneration of the olfactory epithelium, and suppurative inflammation. Incidences of minimal to mild squamous metaplasia in 1,000 and 2,000 ppm males and females and in 500 ppm females were significantly greater than those in the chamber controls. Another lesion associated with isobutyraldehyde exposure was minimal to mild degeneration of the olfactory epithelium in 2,000 ppm males and females. The incidences of suppurative inflammation (rhinitis) in male and female rats exposed to 2,000 ppm were increased compared to the chamber controls. 2-YEAR STUDY IN MICE: Groups of 50 male and 50 female B6C3F1 mice were exposed to 0, 500, 1,000, or 2,000 ppm isobutyraldehyde by inhalation, 6 hours per day, 5 days per week, for 105 weeks. Survival, Body Weights, and Clinical Findings There was an exposure-related decrease in survival of male mice, and the survival of males exposed to 2,000 ppm was marginally lower than that of the chamber controls. The mean body weights of female mice exposed to 1,000 or 2,000 ppm were lower than those of the chamber controls during the second year of the study. Pathology Findings No neoplasms that could be attributed to iso butyraldehyde exposure were observed in mice. Non neoplastic lesions related to isobutyraldehyde exposure were limited to the nose. The incidences of olfactory epithelial degeneration in 1,000 and 2,000 ppm males and females were significantly greater than in the chamber controls. GENETIC TOXICOLOGY: Isobutyraldehyde is mutagenic in vitro and in vivo, with the strongest responses observed in mammalian cell assays that measured chromosomal damage. Results of an initial mutagenicity test in S. typhimurium were negative; a second test, con ducted with different strains and varying concentrations of induced S9 activation enzymes, gave equivocal results. Strongly positive responses were obtained in the mouse lymphoma assay for mutation induction in L5178Y cells without S9 and in cytogenetic tests for induction of sister chromatid exchanges and chromosomal aberrations in cultured Chinese hamster ovary cells. Sister chromatid exchanges were significantly increased with and without S9, but induction of chromosomal aberrations was noted unequivocally only in the absence of S9. No induction of sex-linked recessive lethal mutations was observed in germ cells of male D. melanogaster administered isobutyraldehyde by feeding or by injection. In vivo, isobutyraldehyde was demonstrated to induce chromosomal aberrations in bone marrow cells of male mice, but no increases in micronuclei were observed in bone marrow cells of mice or rats after administration of isobutyraldehyde. All these in vivo cytogenetic studies used doses that reached lethality CONCLUSIONS: Under the conditions of these 2-year inhalation studies, there was no evidence of carcinogenic activity of isobutyraldehyde in male or female F344/N rats or male or female B6C3F1 mice exposed to 500, 1,000, or 2,000 ppm isobutyraldehyde. In male and female rats, exposure to isobutyraldehyde induced squamous metaplasia and suppurative inflammation of the nasal respiratory epithelium and degeneration of the nasal olfactory epithelium. In male and female mice, exposure to isobutyraldehyde caused degeneration of the nasal olfactory epithelium. Synonyms: Dimethylacetaldehyde; 2-formylpropane; isobutanal; isobutylcarboxaldehyde; isobutyral; isobutyric aldehyde; isobutyrylaldehyde; isopropylformaldehyde; 2-methylpropanal; 2-methyl-1-propanal; a-methylpropionaldehyde; 2-methylpropionaldehyde; valine aldehyde

Journal Article↗
PubMed2000

Identification of a naturally occurring Pro385-Ser385 substitution in the GABA(A) receptor alpha6 subunit gene in alcoholics and healthy volunteers.

In the rat, variation in alcohol and benzodiazepine sensitivity has been correlated with an inherited variant of the GABA(A)alpha6 receptor. Our goal was to identify polymorphisms in the human GABA(A)alpha6 receptor gene and determine whether a variant of the receptor is associated with alcoholism. The GABA(A)alpha6 receptor gene coding region was screened in 80 unrelated patients with alcoholism using single strand conformational polymorphism analysis. For rapid genotyping, a Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) assay was developed. A relatively abundant amino acid substitution and three synonymous DNA substitutions were detected. The synonymous variants, 35A>G, 665A>G, and 1031G>C had rare-allele frequencies of 0.25, 0.02, and 0.47, respectively. The Pro385Ser substitution is located in the second intracellular domain of the receptor adjacent to a putative phosphorylation site. Pro385Ser has rarer allele frequencies of 3.3% and 4.8% in 196 Finnish alcoholic patients and 189 controls, respectively (P = NS). A naturally occurring non-conservative Pro385Ser was detected in the GABA(A)alpha6 receptor. The variant is not associated with alcoholism.

Alcoholism↗
PubMed1991

Low nucleotide diversity in man.

The nucleotide diversity (pi) in humans is studied by using published cDNA and genomic sequences that have been carefully checked for sequencing accuracy. This measure of genetic variability is defined as the number of nucleotide differences per site between two randomly chosen sequences from a population. A total of more than 75,000 base pairs from 49 loci are compared. The DNA regions studied are the 5' and 3' untranslated regions and the amino acid coding regions. The coding regions are divided into nondegenerate sites (i.e., sites at which all possible changes are nonsynonymous), twofold degenerate sites (i.e., sites at each of which one of the three possible changes is synonymous) and fourfold degenerate sites (i.e., sites at which all three possible changes are synonymous). The pi values estimated are, respectively, 0.03 and 0.04% for the 5' and 3' UT regions, and 0.03, 0.06 and 0.11% for nondegenerate, twofold degenerate and fourfold degenerate sites. Since the highest pi value is only 0.11%, which is about one order of magnitude lower than those in Drosophila populations, the nucleotide diversity in humans is very low. The low diversity is probably due to a relatively small long-term effective population size rather than any severe bottleneck during human evolution.

Animals↗
PubMed2005

Human SNPs reveal no evidence of frequent positive selection.

We compared the single-nucleotide polymorphisms (SNPs) in humans in 182 housekeeping and 148 tissue-specific genes. SNPs were divided into rare and common polymorphisms based on their frequencies. We found that housekeeping genes tend to be less polymorphic than tissue-specific genes for both rare and common SNPs. Using mouse as a second species for computing sequence divergences, we found no evidence of positive selection: for both housekeeping and tissue-specific genes, the ratio of nonsynonymous to synonymous common SNPs per site showed no significant difference from that of divergence. Similarly, we observed no evidence of positive selection for the 289 and 149 genes that have orthologs available for divergence calculation between humans and chimpanzees and between humans and Old World monkeys, respectively. A comparison with previous SNP studies suggests that approximately 20% of the nonsynonymous SNPs in the human population are nearly neutral and that positive selection in the human genome might not be as frequent as previously thought.

Animals↗
PubMed1999

NTP Toxicology and Carcinogenesis Studies of Oleic Acid Diethanolamine Condensate (CAS No. 93-83-4) in F344/N Rats and B6C3F1 Mice (Dermal Studies).

Oleic acid diethanolamine condensate is widely used as an emollient, thickener, and foam stabilizer present in cosmetic formulations of bath additives, shampoos, conditioners, lipsticks, and hair dyes. Male and female F344/N rats and B6C3F1 mice received dermal applications of diethanolamine in 95% ethanol for 13 weeks or 2 years. Genetic toxicology studies were performed in Salmonella typhimurium and L5178Y mouse lymphoma cells. 13-WEEK STUDY IN RATS: Groups of 10 male and 10 female rats were admin istered 0, 25, 50, 100, 200, or 400 mg oleic acid diethanolamine condensate/kg body weight in ethanol dermally for 13 weeks. All male and female rats survived until the end of the study. The final mean body weights and body weight gains of 200 and 400 mg/kg males and the mean body weight gain of 400 mg/kg females were significantly less than those of the vehicle controls. The only chemical-related clinical finding was irritation of the skin at the site of application in most males administered 100 mg/kg or greater and in all females administered 50 mg/kg or greater. Segmented neutrophil counts were increased relative to the vehicle controls in the 400 mg/kg male group on days 5 and 19, in the 200 mg/kg female group on day 19 and at week 13, and in the 400 mg/kg female group on days 5 and 19 and at week 13. Alkaline phosphatase concentrations were significantly increased in the 200 mg/kg male group on day 19, the 200 mg/kg female group at week 13, and in the 400 mg/kg groups of males and females at week 13. Kidney weights of 200 and 400 mg/kg females were significantly greater than those of the vehicle controls. Lesions of the skin at the site of application included epidermal hyperplasia, parakeratosis, chronic active dermal inflammation, suppurative epidermal inflammation, and sebaceous gland hypertrophy in dosed rats. The severities of these lesions generally increased with increasing dose. 13-WEEK STUDY IN MICE: Groups of 10 male and 10 female mice were admin istered 0, 50, 100, 200, 400, or 800 mg oleic acid diethanolamine condensate/kg body weight in ethanol dermally for 13 weeks. All male and female mice except one 800 mg/kg male survived until the end of the study. Final mean body weights and body weight gains of 800 mg/kg males and females and 400 mg/kg females were significantly less than those of the vehicle controls. Clinical findings in dosed mice included irritation of the skin at the site of application. Irritation occurred in all surviving dosed males and in most females administered 100 mg/kg or greater and progressed to ulcer in one 800 mg/kg male. The heart weights of 400 and 800 mg/kg males and females and 200 mg/kg females and the kidney weights of 50, 100, and 400 mg/kg males were significantly greater than those of the vehicle controls. Relative to the vehicle controls, the liver weights were increased in all dosed groups. Lesions of the skin at the site of application in dosed mice included epidermal hyperplasia, parakeratosis, suppurative epidermal inflammation, chronic active dermal inflammation, sebaceous gland hypertrophy, and ulcer. The severities of these lesions generally increased with increasing dose. 2-YEAR STUDY IN RATS: Groups of 50 male and 50 female rats were administered 0, 50, or 100 mg oleic acid diethanolamine condensate/kg body weight in ethanol dermally for 2 years. Survival, Body Weights, and Clinical Findings: Survival of dosed male and female rats was similar to that of the vehicle control groups. Mean body weights of 100 mg/kg males were slightly less than those of the vehicle controls throughout most of the study. Mean body weights of 100 mg/kg females were less than those of the vehicle controls beginning at week 24. The only significant treatment-related clinical finding was mild to moderate irritation of the skin at the site of application in dosed males and females. Pathology Findings: The predominant effects of oleic acid diethanolamine condensate administration were minimal to moderate nonneoplastic lesions of the skin at the site of application in dosed rats. These lesioe lesions included epidermal hyperplasia, sebaceous gland hyperplasia, hyperkeratosis, parakeratosis, chronic active dermal inflammation, and ulcer. 2-YEAR STUDY IN MICE: Groups of 55 male and 55 female mice were administered 0, 15, or 30 mg oleic acid diethanolamine condensate/kg body weight in ethanol dermally for 2 years. Five animals from each group were evaluated at 3 months for gross lesions and skin histopathology. Survival, Body Weights, and Clinical Findings: Survival of dosed male and female mice was similar to that of the vehicle control groups. Mean body weights of dosed males and of 15 mg/kg females were similar to those of the vehicle controls throughout the study. Mean body weights of 30 mg/kg females were less than those of the vehicle controls from week 76 until the end of the study. The only significant treatment-related clinical finding was irritation of the skin at the site of application in 30 mg/kg males. Pathology Findings: The incidences of epidermal hyperplasia, sebaceous gland hyperplasia, and chronic active inflammation of the dermis in all dosed groups were significantly increased relative to the vehicle controls at 3 months and at 2 years. The increased incidences of hyperkeratosis in dosed males at 3 months and in dosed males and females at 2 years, of parakeratosis in 30 mg/kg males at 3 months and 2 years, and of ulcer in 30 mg/kg males and exudate in 30 mg/kg males and females at 2 years were also attributed to chem ical administration. GENETIC TOXICOLOGY: Oleic acid diethanolamine condensate was not mutagenic in S. typhimurium strain TA97, TA98, TA100, or TA1535, with or without S9 metabolic activation enzymes. In addition, it did not induce mutations in mouse L5178Y lymphoma cells treated with or without S9. CONCLUSIONS: Under the conditions of these 2-year dermal studies, there was no evidence of carcinogenic activity of oleic acid diethanolamine condensate in male or female F344/N rats administered 50 or 100 mg/kg or in male or female B6C3F1 mice administered 15 or 30 mg/kg. Dermal administration of oleic acid diethanolamine condensate to male and female rats was associated with epidermal hyperplasia, sebaceous gland hyper plasia, hyperkeratosis, parakeratosis, chronic active inflammation of the dermis, and ulceration of the skin at the site of application. Dermal administration of oleic acid diethanolamine condensate to mice was associated with epidermal hyperplasia, sebaceous gland hyperplasia, hyperkeratosis, chronic active inflammation of the dermis, and exudate of the skin at the site of application in males and females and parakeratosis and ulcer of the skin at the site of application in males. Synonyms: Diethanolamine oleate; diethanolammonium oleate; (Z)-9-octadecenoic acid, compound with 2,2.-imnobis(ethanol) (1:1); oleamide diethanolamine

Journal Article↗
PubMed1992

NTP Toxicology and Carcinogenesis Studies of Methyl Bromide (CAS: 74-83-9) in B6C3F1 Mice (Inhalation Studies).

Methyl bromide is widely used as a fumigant and pesticide. Toxicology and carcinogenesis studies were conducted by exposing groups of male and female B6C3F1 mice to methyl bromide (99.8% pure) by inhalation 6 hours per day, 5 days per week, for 14 days, 6 weeks, 13 weeks, or 2 years. Six-week and 13-week inhalation toxicity studies in F344/N rats were conducted concurrently with the mouse studies. Hematology parameters were measured during the 6-week, 13-week, and 2-year studies. Quantitative neurobehavioral testing was performed during the 14-day, 13-week and 2-year studies. Genetic toxicology studies were conducted for gene mutation induction in Salmonella typhimurium and for induction of sister chromatid exchanges in mouse bone marrow cells and of micronuclei from peripheral blood erythrocytes. 14-Day Studies: Groups of five B6C3F1 mice of each sex were exposed to 0, 12, 25, 50, 100, or 200 ppm methyl bromide by inhalation 6 hours per day, 5 days per week for 2 weeks. Only four female mice and one male mouse survived 10 exposures at 200 ppm. No deaths occurred at the lower doses. Neurobehavioral effects including trembling and paralysis were noted in all groups, but were most pronounced in the three highest dose groups. Red urine was noted in the mice exposed to 200 ppm. 13-Week Studies : Groups of 10 mice of each sex were exposed to 0, 10, 20, 40, 80, or 120 ppm methyl bromide by inhalation 6 hours per day, 5 days per week for 13 weeks. Additional groups of eight to 17 mice were concurrently exposed for neurobehavioral and genetic toxicology studies. The final mean body weight of males exposed to 120 ppm was significantly (12%) lower than that of the controls. Four of 24 males exposed to 120 ppm died during the study. Groups of 10 rats of each sex were exposed to 0, 30, 60, or 120 ppm methyl bromide by inhalation 6 hours per day, 5 days per week for 13 weeks. Additional groups of eight rats were concurrently exposed for neurobehavioral studies. Final mean body weights of rats exposed to 120 ppm were 12% lower than those of the controls for males and 13% lower for females. No rats died as a result of methyl bromide exposure during the studies. Special 6-Week Target Organ Toxicity Studies: Neither the 14-day nor the 13-week studies provided strong evidence for specific organ toxicity. Six-week studies were therefore conducted to identify target organs for the 2-year studies. Groups of 20 rats and mice of each sex were exposed to methyl bromide by inhalation for 6 hours per day, 5 days per week for 6 weeks at a dose of 160 ppm. Mortality rates exceeded 50% in the male mice after eight exposures, in female mice after six exposures, and in male rats after 14 exposures. Only the female rat group survived 30 exposures with less than 50% mortality. The study identified the brain, kidney, nasal cavity, heart, adrenal gland, liver, and testis as the primary organs to examine for toxicity in the 2-year methyl bromide inhalation studies. 2-Year Studies: Groups of 70 B6C3F1 mice of each sex were exposed to methyl bromide by inhalation at 0, 10, 33, or 100 ppm for 6 hours per day, 5 days per week for up to 103 weeks. Additional groups of 16 mice were included for neurobehavioral evaluations throughout the 2-year studies. By 20 weeks (139 days), 27 males and 7 females exposed to 100 ppm had died and methyl bromide exposure was discontinued for the remaining mice in this dose group. Ten female mice from the 100 ppm group predesignated for the 15-month interim evaluation were killed on schedule and all other high-dose animals were allowed to live to term (24 months) for evaluation of chronic toxicity and carcinogenicity. Clinical signs indicative of neurotoxicity, including tremors, abnormal posture, tachypnea, and hind leg paralysis, persisted in these high-dose mice until the end of the studies. Final mean body weights of surviving 100 ppm males and females were markedly lower (33% and 31%) than those of the controls. Neurobehavioral changes occurred in male and female mice initially exposed to 100 ppm methyl bromide, with more prnitially exposed to 100 ppm methyl bromide, with more pronounced changes observed in males. In general, these animals were less active and manifested a heightened sensitivity in the startle response than mice in other dose groups. Exposure to methyl bromide was not carcinogenic under the conditions of these studies. However, there was an increase in the incidence of several nonneoplastic lesions in the brain, heart, bone (sternum), and nose. Degenerative changes in the cerebellum and cerebrum occurred in males and females exposed to 100 ppm. Myocardial degeneration and cardiomyopathy were observed in the hearts of mice exposed to 100 ppm. An increased incidence of sternal dysplasia was seen in treated animals, particularly in those exposed to 100 ppm. An increased incidence of olfactory epithelial necrosis and metaplasia within the nasal cavity was seen in the mice exposed to 100 ppm, particularly males. Genetic Toxicology: Methyl bromide was positive for induction of gene mutations in Salmonella typhimuriumstrain TA100, with and without exogenous metabolic activation; negative results were obtained with TA98 in this assay. In vivo, methyl bromide induced sister chromatid exchanges in bone marrow cells and micronuclei in peripheral erythrocytes of female mice exposed by inhalation for 14 days. No significant increase in either sister chromatid exchanges or micronuclei was observed in male or female mice exposed to methyl bromide by inhalation for 4, 8, or 12 weeks. Conclusions: Under the conditions of these 2-year inhalation studies, methyl bromide caused degenerative changes in the cerebellum and cerebrum, myocardial degeneration and cardiomyopathy, sternal dysplasia, and olfactory epithelial necrosis and metaplasia. Toxic effects persisted although exposure to methyl bromide in the 100 ppm group terminated after 20 weeks. There was no evidence of carcinogenic activity of methyl bromide in male or female B6C3F1 mice exposed to 10, 33, or 100 ppm. Synonym: Bromomethane

Journal Article↗
PubMed1993

NTP Toxicology and Carcinogenesis Studies of Ethylene Glycol (CAS No. 107-21-1) in B6C3F1 Mice (Feed Studies).

Ethylene glycol is a major constituent of motor vehicle antifreeze-coolant fluids and is also found in other commercial products including hydraulic brake fluids, adhesives, printer's inks, and wood stains. It is used in the manufacture of polyester films and fibers, polyethylene terephthalate (PET) solid state resins, plasticizers, elastomers, cellophane, and other products. Previous 13-week and 2-year studies of ethylene glycol in F344 rats were considered adequate to evaluate the toxicology and carcinogenicity of ethylene glycol in this species and strain; therefore, the present studies were conducted in mice only. Toxicology and carcinogenesis studies were conducted by administering ethylene glycol (greater than 99% pure) in feed to male and female B6C3F1 mice for 13 weeks and 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium, mouse lymphoma L5178Y cells, and Chinese hamster ovary cells. 13-Week Studies: Groups of 10 male and 10 female mice received feed containing 0, 3,200, 6,300, 12,500, 25,000 or 50,000 ppm ethylene glycol. All mice survived to the end of the studies. Final mean body weights of dosed male and female mice and feed consumption of dosed males were similar to those of the controls. Feed consumption of dosed females was significantly greater than that of controls. Absolute and relative organ weights of mice administered ethylene glycol were generally similar to those of controls throughout the study. No chemical-related clinical findings were observed. Chemical-related kidney and liver lesions, seen only in 25,000 and 50,000 ppm male mice, consisted of nephropathy and centrilobular hepatocellular hyaline degeneration (cytoplasmic accumulation of non-birefringent, eosinophilic, globular, or crystalline material resembling erythrocyte fragments). 2-Year Studies: Groups of 60 mice received diets containing ethylene glycol for up to 103 weeks (males: 0, 6,250, 12,500, or 25,000 ppm; females: 0, 12,500, 25,000, or 50,000 ppm). These concentrations correspond to daily doses of approximately 1,500, 3,000, or 6,000 mg/kg body weight for male mice and 3,000, 6,000, or 12,000 mg/kg for females. Dietary concentrations greater than 50,000 ppm have the potential to affect the nutritional value of the feed. Interim evaluations were performed on six males and nine or ten females from each dose group at 15 months. Survival, Body Weights, Feed Consumption, and Clinical Findings in the 2-Year Studies: At the end of the 2-year studies, survival rates of male and female mice exposed to ethylene glycol were similar to those of controls. Mean body weights and feed consumption of exposed male and female groups were also similar to those of controls. No clinical findings associated with the administration of ethylene glycol were observed. Pathology Findings: No chemical-related neoplasms were observed in male or female mice in these studies. Hepatocellular hyaline degeneration was seen in mid- and high-dose male and high-dose female mice. Pulmonary arterial medial hyperplasia was observed at an increased incidence in exposed females but not in exposed males. Incidence and severity of nephropathy were not affected by treatment in either sex. Small numbers of oxalate-like crystals, calculi, or both were noted in renal tubules, urethrae, and/or urinary bladders in a few high-dose male mice. Genetic Toxicology: Ethylene glycol did not induce gene mutations in Salmonella typhimurium strains TA98, TA100, TA1535, and TA1537, trifluorothymidine resistance in mouse L5178Y lymphoma cells, or sister chromatid exchanges or chromosomal aberrations in Chinese hamster ovary cells. All tests were conducted with and without exogenous metabolic activation (S9). Conclusions: Under the conditions of these 2-year feed studies, there was no evidence of carcinogenic activity of ethylene glycol in male B6C3F1 mice receiving 6,250, 12,500, or 25,000 ppm, or in female B6C3F1 mice receiving 12,500, 25,000, or 50,000 ppm. Administration of ethylene glycol resulted in hepatocellular hyaline degeneration in male mice fed diets diets containing 12,500 or 25,000 ppm and in female mice fed diets containing 50,000 ppm. An increased incidence of medial hyperplasia of small pulmonary arteries and arterioles occurred in female mice fed diets containing 12,500, 25,000, or 50,000 ppm ethylene glycol. Synonyms: 1,2-dihydroxyethane; ethane-1,2-diol; 1,2-ethanediol; ethylene alcohol; ethylene dihydrate; glycol; glycol alcohol; 2-hydroxyethanol; monoethylene glycol

Journal Article↗
PubMed2005

Synonymous SNPs provide evidence for selective constraint on human exonic splicing enhancers.

The human SNP database was used to detect selection on 238 hexamers previously identified as exonic splicing enhancers (ESEs). We compared the distribution of the 238 putative ESEs in biallelic and triallelic SNPs within five different functional categories of the SNP database: synonymous, nonsynonymous, introns, UTRs, and nongenic SNPs. Since true ESEs do not function outside of exons, SNPs that disrupt ESE motifs were expected to be more common in nonexonic portions of the genome. Our results supported this expectation: ESEs were least prevalent within synonymous SNPs and most common in nongenic SNPs. There were approximately 11% fewer ESEs within synonymous biallelic SNPs than expected under no selective constraint. We also compared the frequency of neutral SNPs, those where neither allele was an ESE, with deleterious SNPs, those where one or more alleles was an ESE, across the five different functional classes of SNPs. In comparison with the other functional classes of SNPs, synonymous SNPs contained an excess of neutral variants (+1.64% and +6.04% for biallelic and triallelic SNPs, respectively) and a dearth of deleterious variants (-13.11% and -52.39% for biallelic and triallelic SNPs, respectively). The observed patterns were consistent with purifying selection on the 238 hexamers to maintain their function as ESEs. However, in contrast to previous work, we did not find evidence for selection to maintain ESE function at nonsynonymous SNPs because selection at the protein level probably obscured any difference at the level of ESE function.

Alternative Splicing↗
PubMed1992

Polymorphism and balancing selection at major histocompatibility complex loci.

Amino acid replacements in the peptide-binding region (PBR) of the functional major histocompatibility complex (Mhc) genes appear to be driven by balancing selection. Of the various types of balancing selection, we have examined a model equivalent to overdominance that confers heterozygote advantage. As discussed by A. Robertson, overdominance selection tends to maintain alleles that have more or less the same degree of heterozygote advantage. Because of this symmetry, the model makes various testable predictions about the genealogical relationships among different alleles and provides ways of analyzing DNA sequences of Mhc alleles. In this paper, we analyze DNA sequences of 85 alleles at the HLA-A, -B, -C, -DRB1 and -DQB1 loci with respect to the number of alleles and extent of nucleotide differences at the PBR, as well as at the synonymous (presumably neutral) sites. Theory suggests that the number of alleles that differ at the sites targeted by selection (presumably the nonsynonymous sites in the PBR) should be equal to the mean number of nucleotide substitutions among pairs of alleles. We also demonstrate that the nucleotide substitution rate at the targeted sites relative to that of neutral sites may be much larger than 1. The predictions of the presented model are in surprisingly good agreement with the actual data and thus provide means for inferring certain population parameters. For overdominance selection in a finite population at equilibrium, the product of selection intensity (s) against homozygotes and the effective population size (N) is estimated to be 350-3000, being largest at the B locus and smallest at the C locus. We argue that N is of the order of 10(5) and s is several percent at most, if the mutation rate per site per generation is 10(-8).

Alleles↗
PubMed2002

Vanishing GC-rich isochores in mammalian genomes.

To understand the origin and evolution of isochores-the peculiar spatial distribution of GC content within mammalian genomes-we analyzed the synonymous substitution pattern in coding sequences from closely related species in different mammalian orders. In primate and cetartiodactyls, GC-rich genes are undergoing a large excess of GC --> AT substitutions over AT --> GC substitutions: GC-rich isochores are slowly disappearing from the genome of these two mammalian orders. In rodents, our analyses suggest both a decrease in GC content of GC-rich isochores and an increase in GC-poor isochores, but more data will be necessary to assess the significance of this pattern. These observations question the conclusions of previous works that assumed that base composition was at equilibrium. Analysis of allele frequency in human polymorphism data, however, confirmed that in the GC-rich parts of the genome, GC alleles have a higher probability of fixation than AT alleles. This fixation bias appears not strong enough to overcome the large excess of GC --> AT mutations. Thus, whatever the evolutionary force (neutral or selective) at the origin of GC-rich isochores, this force is no longer effective in mammals. We propose a model based on the biased gene conversion hypothesis that accounts for the origin of GC-rich isochores in the ancestral amniote genome and for their decline in present-day mammals.

Alleles↗