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Sample records for group gstm1 null

  1. Use of site-directed mutagenesis of allele-specific PCR primers to identify the GSTM1 A, GSTM1 B, GSTM1 A,B and GSTM1 null polymorphisms at the glutathione S-transferase, GSTM1 locus.

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    Fryer, A A; Zhao, L.; Alldersea, J; Pearson, W R; Strange, R C

    1993-01-01

    We describe the identification of the GSTM1 null, GSTM1 A, GSTM1 B and GSTM1 A,B polymorphisms at the glutathione S-transferase GSTM1 locus using a single-step PCR method. Target DNA was amplified using primers to intron 6 and exon 7 with site-directed mutagenesis being used to introduce a restriction site in DNA amplified from GSTM1 *A, thereby allowing differentiation of this allele and GSTM1 *B. The accuracy of this approach in identifying the GSTM1 A, GSTM1 B, GSTM1 A,B and GSTM1 null pol...

  2. The GSTM1 null genotype increased risk of gastric cancer: a meta-analysis based on 46 studies.

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    Yi Zhao

    Full Text Available BACKGROUND: Glutathione S-transferases M1 (GSTM1 is an important phase II metabolizing enzyme. The null genotype of GSTM1 causes total loss of GSTM1 enzyme activity and numerous studies have investigated the association between GSTM1 null genotype and gastric cancer risk. METHODS: This meta-analysis was designed to investigate the relationship between GSTM1 null genotype and susceptibility to gastric cancer and assess the influence of Helicobacter pylori infection, smoking, Lauren's classification, and other factors. Odds ratios (ORs and 95% confidence intervals (CIs were calculated to estimate the association strength. RESULTS: A total of 46 eligible studies were indentified and analyzed in this meta-analysis, including 8138 cases of gastric cancer and 13867 controls. Pooled results showed that the GSTM1 null genotype was associated with a significantly increased risk of gastric cancer (OR=1.217, 95% CI: 1.113-1.331, P(heterogeneity<0.001. Sub-group analysis suggested that the significant association was only observed in Asians (OR=1.273, 95%: 1.137-1.426, P(heterogeneity= 0.002, but not in Caucasians. The increased risk was found among H. pylori positive population (OR=1.928, 95% CI: 1.028-3.615, P(heterogeneity=0.065, while no association was found among H. pylori negative population (OR=0.969, 95% CI: 0.618-1.521, P(heterogeneity=0.168. For smoking status, the GSTM1 null genotype increased risk of gastric cancer in both ever-smokers and non-smokers. Source of control, sample size, location of tumor and Lauren's classification did not modify the association. CONCLUSIONS: In this meta-analysis based on 46 epidemiological studies, we show that the GSTM1 null genotype is associated with an increased risk of gastric cancer among Asians but not among Caucasians. H. pylori infection but not smoking status could modify the association.

  3. Assessment of the association between GSTM1 null genotype and risk of type 2 diabetes.

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    Yi, Ran; Liu, Bin; Dong, Qi

    2013-06-01

    Many studies have investigated the association between Glutathione S-Transferase M1 (GSTM1) null genotype and risk of diabetes mellitus, but the impact of GSTM1 null genotype on diabetes mellitus is unclear owing to the obvious inconsistence among those studies. This study aimed to quantify the strength of association between GSTM1 null genotype and risk of diabetes mellitus. We searched the PubMed, Embase and Wangfang databases for studies relating the association between GSTM1 null genotype and risk of diabetes mellitus. We estimated summary odds ratio (OR) with their 95 % confidence interval (95 % CI) to assess the association. Subgroup analyses were performed by type of diabetes and ethnicity. 10 case-control studies with 7, 054 subjects were included into this meta-analysis. Meta-analysis of total 10 studies showed GSTM1 null genotype was associated increased risk of diabetes mellitus (OR = 1.59, 95 % CI 1.14-2.22, P = 0.007). Subgroup analyses by type of diabetes mellitus suggested GSTM1 null genotype was associated increased risk of type 2 diabetes (OR = 1.90, 95 % CI 1.37-2.64, P null genotype and increased risk of type 2 diabetes. The cumulative meta-analyses showed a trend of obvious association between GSTM1 null genotype and risk of type 2 diabetes as information accumulated. No evidence of publication bias was observed. Thus, evidence from current meta-analysis suggests an association between GSTM1 null genotype and risk of type 2 diabetes.

  4. Susceptibility to hepatocellular carcinoma associated with null genotypes of GSTM1 and GSTT1

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    Jian Chao Bian; Fu Min Shen; Li Shen; Tian Ru Wang; Xiao Hong Wang; Gong Chao Chen; Jin Bing Wang

    2000-01-01

    ALM In order to study the association between the null genotypes of GSTM1 and GSTT1 and the genetic susceptibility to hepatocellular carcinoma (HCC). METHODS The genotypes of GSTM1 and GSTT1 of 63 cases of HCC and 88 controls were detected with the multiple PCR technique. RESULTS The frequency of GSTM1 null genotype was 57.1% among the cases, and 42.0% among the controls, the difference being statistically significant (x2 = 3.35, P = 0.067),but X2 value approaching the significance level.The odds ratio was 1.84 (95% Cl=0.91 - 3.37).The frequency of GSTT1 non-null genotype was 87.3% among the cases and 62.5% among the controls, the difference being statistically significant (X2=11.42, P=0.0007274). The odds ratio was 4.13 (95% Cl = 1.64 - 10.70).According to the cross analysis, the GSTT1 nonnull genotype was more closely associated with HCC than GSTM1 null genotype, and these two factors play an approximate addlitive interaction in the occurrence of HCC. CONCLUSION The persons with GSTM1 nullgenotype and GSTT1 non-null genotype have the increased risk to HCC.

  5. GSTM1 and GSTT1 null polymorphisms and childhood acute leukemia risk: evidence from 26 case-control studies.

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    Qiuqin Tang

    Full Text Available Several molecular epidemiological studies have been conducted to examine the association between glutathione S-transferase mu-1 (GSTM1 and glutathione S-transferase theta-1 (GSTT1 null polymorphisms and childhood acute leukemia; however, the conclusions remain controversial. We performed an extensive meta-analysis on 26 published case-control studies with a total of 3252 cases and 5024 controls. Crude odds ratios (ORs with 95% confidence interval were used to assess the strength of association between childhood acute leukemia risk and polymorphisms of GSTM1 and GSTT1. With respect to GSTM1 polymorphism, significantly increased risk of childhood acute leukemia was observed in the overall analysis (OR = 1.30; 95%CI, 1.11-1.51. Furthermore, a stratification analysis showed that the risk of GSTM1 polymorphism are associated with childhood acute leukemia in group of Asians (OR = 1.94; 95%CI, 1.53-2.46, Blacks (OR = 1.76; 95%CI, 1.07-2.91, ALL (OR = 1.33; 95%CI, 1.13-1.58, '< 100 cases and <100 controls' (OR = 1.79; 95%CI, 1.21-2.64, '≥ 100 cases and ≥ 100 controls' (OR = 1.25; 95%CI, 1.02-1.52, and population-based control source (OR = 1.40; 95%CI, 1.15-1.69. With respect to GSTT1 polymorphism, significant association with childhood acute leukemia risk was only found in subgroup of Asian. This meta-analysis supports that GSTM1 null polymorphism is capable of causing childhood acute leukemia susceptibility.

  6. Combined Effects of GSTM1 Null Allele and APOL1 Renal Risk Alleles in CKD Progression in the African American Study of Kidney Disease and Hypertension Trial.

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    Bodonyi-Kovacs, Gabor; Ma, Jennie Z; Chang, Jamison; Lipkowitz, Michael S; Kopp, Jeffrey B; Winkler, Cheryl Ann; Le, Thu H

    2016-10-01

    Apolipoprotein L-1 (APOL1) high-risk alleles and the glutathione-S-transferase-μ1 (GSTM1) null allele have been shown separately to associate with CKD progression in the African American Study of Kidney Disease and Hypertension (AASK) trial participants. Here, we determined combined effects of GSTM1 null and APOL1 high-risk alleles on clinical outcomes in 682 AASK participants who were classified into four groups by GSTM1 null or active genotype and APOL1 high- or low-risk genotype. We assessed survival differences among these groups by log-rank test and Cox regression adjusted for important clinical variables for time to GFR event (change in GFR of 50% or 25-ml/min per 1.73 m(2) decline), incident ESRD, death, or composite outcomes. The groups differed significantly in event-free survival for incident ESRD and composite outcomes (P≤0.001 by log-rank test). Compared with the reference GSTM1 active/APOL1 low-risk group, other groups had these hazard ratios for the composite outcome of incident ESRD and change in GFR: GSTM1 active/APOL1 high-risk hazard ratio, 2.13; 95% confidence interval, 0.76 to 5.90 (P=0.15); GSTM1 null/APOL1 low-risk hazard ratio, 2.05; 95% confidence interval, 1.08 to 3.88 (P=0.03); and GSTM1 null/APOL1 high-risk hazard ratio, 3.0; 95% confidence interval, 1.51 to 5.96 (P=0.002). In conclusion, GSTM1 null and APOL1 high-risk alleles deleteriously affect CKD progression among blacks with hypertension, and subjects with both GSTM1 null and APOL1 high-risk genotypes had highest risk of adverse renal outcomes. Larger cohorts are needed to fully explore interactions of GSTM1 and APOL1 genotypes in other subgroups.

  7. Null genotypes of GSTM1 and GSTT1 contribute to increased risk of diabetes mellitus: a meta-analysis.

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    Zhang, Jingwen; Liu, Hu; Yan, Hongyi; Huang, Guoliang; Wang, Bin

    2013-04-15

    Diabetes mellitus (DM) is a common disease which results from various causes including genetic and environmental factors. Glutathione S-Transferase M1 (GSTM1) and Glutathione S-Transferase T1 (GSTT1) genes are polymorphic in human and the null genotypes lead to the absence of enzyme function. Many studies assessed the associations between GSTM1/GSTT1 null genotypes and DM risk but reported conflicting results. In order to get a more precise estimate of the associations of GSTM1/GSTT1 null genotypes with DM risk, we performed this meta-analysis. Published literature from PubMed, Embase and China Biology Medicine (CBM) databases was searched for eligible studies. Pooled odds ratios (OR) and corresponding 95% confidence intervals (95%CI) were calculated using a fixed- or random-effects model. 11 publications (a total of 2577 cases and 4572 controls) were finally included into this meta-analysis. Meta-analyses indicated that null genotypes of GSTM1/GSTT1 and dual null genotype of GSTM1-GSTT1 were all associated with increased risk of DM (GSTM1: OR random-effects=1.60, 95%CI 1.10-2.34, POR=0.014; GSTT1: OR random-effects=1.47, 95%CI 1.12-1.92, POR=0.005; GSTM1-GSTT1: OR fixed-effects=1.83, 95%CI 1.30-2.59, POR=0.001). Subgroup by ethnicity suggested significant associations between null genotypes of GSTM1 and GSTT1 and DM risk among Asians (GSTM1: OR random-effects=1.77, 95%CI 1.24-2.53, POR=0.002; GSTT1: OR random-effects=1.58, 95%CI 1.09-2.27, POR=0.015). This meta-analysis suggests null genotypes of GSTM1/GSTT1 and dual null genotype of GSTM1-GSTT1 are all associated with increased risk of DM, and null genotypes of GSTM1/GSTT1 and dual null genotype of GSTM1-GSTT1 are potential biomarkers of DM.

  8. GSTM1 null genotype and susceptibility to cervical cancer in the Chinese population: An updated meta-analysis

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    Ping Sun

    2016-01-01

    Conclusion: This meta-analysis provides the evidence that GSTM1 null genotype may contribute to the CC development in Chinese and studies with large sample size and wider spectrum of population are warranted to verify this finding.

  9. GSTM1 null genotype and gastric cancer risk in the Chinese population: an updated meta-analysis and review.

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    Zhang, Xi-Liang; Cui, Yong-Hui

    2015-01-01

    Although a number of studies have been conducted on the association between the GSTM1 null genotype and gastric cancer in People's Republic of China, this association remains elusive and controversial. To clarify the effects of the GSTM1 null genotype on the risk of gastric cancer, an updated meta-analysis was performed in the Chinese population. Related studies were identified from PubMed, Springer Link, Ovid, Chinese Wanfang Data Knowledge Service Platform, Chinese National Knowledge Infrastructure (CNKI), and Chinese Biology Medicine (CBM) up to November 5, 2014. A total of 25 studies including 3,491 cases and 5,921 controls were included in this meta-analysis. Overall, a significant association (odds ratio [OR] =1.47, 95% CI: 1.28-1.69) was found between the null GSTM1 and gastric cancer risk when all studies in Chinese population were pooled into the meta-analysis. In subgroup analyses stratified by quality score, geographic area, and source of controls, the same results were observed. Additionally, a significant association was found both in smokers and non-smokers. This meta-analysis showed that the null GSTM1 may be a potential biomarker for gastric cancer risk in Chinese, and further studies with gene-gene and gene-environment interactions are required for definite conclusions.

  10. Enhancement of systemic and sputum granulocyte response to inhaled endotoxin in people with the GSTM1 null genotype

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    To determine if the GSTM1 null genotype is a risk factor for increased inflammatory response to inhaled endotoxin. Methods 35 volunteers who had undergone inhalation challenge with a 20 000 endotoxin unit dose of Clinical Center Reference Endotoxin (CCRE) were genotyped for the G...

  11. Association of GSTM1 null allele with prostate cancer risk: evidence from 36 case-control studies.

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    Bingbing Wei

    Full Text Available BACKGROUND: Glutathione S-transferase M1 (GSTM1 is thought to be involved in detoxifying several carcinogens and may play a vital role in tumorigenesis. Numerous studies have evaluated the association between GSTM1 null/present polymorphism and risk of prostate cancer (PCa. However, the results remain inconsistent. To derive a more precise estimation, we performed a meta-analysis. METHODOLOGY/PRINCIPAL FINDINGS: A comprehensive search was conducted to identify all eligible case-control studies. We used odds ratios (ORs with 95% confidence intervals (CIs to assess the strength of the association. The overall association was significant (OR = 1.28, 95% CI: 1.11-1.48, P = 0.001. Moreover, subgroup analyses showed GSTM1 null genotype significantly associated with PCa risk among Asians (OR = 1.35, 95% CI: 1.03-1.78, P = 0.03 but not among Caucasians (OR = 1.12, 95% CI: 0.96-1.31, P = 0.16. In addition, we did not find that smoking modified the genotype effect on the risk of PCa. CONCLUSIONS/SIGNIFICANCE: The present meta-analysis suggested that GSTM1 null allele was a low-penetrant risk factor for PCa among Asians.

  12. GSTM1 null genotype and gastric cancer risk in the Chinese population: an updated meta-analysis and review

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    Zhang XL

    2015-04-01

    Full Text Available Xi-Liang Zhang, Yong-Hui Cui Department of Gastroenterology, The First People’s Hospital of Shangqiu City, Shangqiu, Henan, People’s Republic of China Abstract: Although a number of studies have been conducted on the association between the GSTM1 null genotype and gastric cancer in People’s Republic of China, this association remains elusive and controversial. To clarify the effects of the GSTM1 null genotype on the risk of gastric cancer, an updated meta-analysis was performed in the Chinese population. Related studies were identified from PubMed, Springer Link, Ovid, Chinese Wanfang Data Knowledge Service Platform, Chinese National Knowledge Infrastructure (CNKI, and Chinese Biology Medicine (CBM up to November 5, 2014. A total of 25 studies including 3,491 cases and 5,921 controls were included in this meta-analysis. Overall, a significant association (odds ratio [OR] =1.47, 95% CI: 1.28–1.69 was found between the null GSTM1 and gastric cancer risk when all studies in Chinese population were pooled into the meta-analysis. In subgroup analyses stratified by quality score, geographic area, and source of controls, the same results were observed. Additionally, a significant association was found both in smokers and non-smokers. This meta-analysis showed that the null GSTM1 may be a potential biomarker for gastric cancer risk in Chinese, and further studies with gene–gene and gene–environment interactions are required for definite conclusions. Keywords: meta-analysis, GSTM1, polymorphism, gastric cancer

  13. CYP1A1 (Ile462Val), CYP1B1 (Ala119Ser and Val432Leu), GSTM1 (null), and GSTT1 (null) polymorphisms and bladder cancer risk in a Turkish population.

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    Berber, Ufuk; Yilmaz, Ismail; Yilmaz, Omer; Haholu, Aptullah; Kucukodaci, Zafer; Ates, Ferhat; Demirel, Dilaver

    2013-01-01

    We aimed to investigate bladder cancer risk with reference to polymorphic variants of cytochrome p450 (CYP) 1A1, CYP1B1, glutathione S-transferase (GST) M1, and GSTT1 genes in a case control study. Polymorphisms were examined in 114 bladder cancer patients and 114 age and sex-matched cancer-free subjects. Genotypes were determined using allele specific PCR for CYP1A1 and CYP1B1 genes, and by multiplex PCR and melting curve analysis for GSTM1 and GSTT1 genes. Our results revealed a statistically significant increased bladder cancer risk for GSTT1 null genotype carriers with an odds ratio of 3.06 (95% confidence interval=1.39-6.74, p=0.006). Differences of CYP1A1, CYP1B1 and GSTM1 genotype frequencies were not statistically significant between patients and controls. However, the specific combination of GSTM1 null, GSTT1 null, and CYP1B1 codon 119 risk allele carriers and specific combination of GSTM1 present, GSTT1 null, and CYP1B1 432 risk allele carriers exhibited increased cancer risk in the combined analysis. We did not observe any association between different genotype groups and prognostic tumor characteristics of bladder cancer. Our results indicate that inherited absence of GSTT1 gene may be associated with bladder cancer susceptibility, and specific combinations of GSTM1, GSTT1 and CYP1B1 gene polymorphisms may modify bladder cancer risk in the Turkish population, without any association being observed for CYP1A1 gene polymorphism and bladder cancer risk.

  14. Combined GSTM1-Null, GSTT1-Active, GSTA1 Low-Activity and GSTP1-Variant Genotype Is Associated with Increased Risk of Clear Cell Renal Cell Carcinoma.

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    Coric, Vesna M; Simic, Tatjana P; Pekmezovic, Tatjana D; Basta-Jovanovic, Gordana M; Savic Radojevic, Ana R; Radojevic-Skodric, Sanja M; Matic, Marija G; Dragicevic, Dejan P; Radic, Tanja M; Bogdanovic, Ljiljana M; Dzamic, Zoran M; Pljesa-Ercegovac, Marija S

    2016-01-01

    The aim of this study was to evaluate specific glutathione S-transferase (GST) gene variants as determinants of risk in patients with clear cell renal cell carcinoma (cRCC), independently or simultaneously with established RCC risk factors, as well as to discern whether phenotype changes reflect genotype-associated risk. GSTA1, GSTM1, GSTP1 and GSTT1 genotypes were determined in 199 cRCC patients and 274 matched controls. Benzo(a)pyrene diolepoxide (BPDE)-DNA adducts were determined in DNA samples obtained from cRCC patients by ELISA method. Significant association between GST genotype and risk of cRCC development was found for the GSTM1-null and GSTP1-variant genotype (p = 0.02 and pnull, GSTT1-active, GSTA1-low activity and GSTP1-variant genotype, exhibiting 9.32-fold elevated cRCC risk compared to the reference genotype combination (p = 0.04). Significant association between GST genotype and cRCC risk in smokers was found only for the GSTP1 genotype, while GSTM1-null/GSTP1-variant/GSTA1 low-activity genotype combination was present in 94% of smokers with cRCC, increasing the risk of cRCC up to 7.57 (p = 0.02). Furthermore, cRCC smokers with GSTM1-null genotype had significantly higher concentration of BPDE-DNA adducts in comparison with GSTM1-active cRCC smokers (p = 0.05). GSTM1, GSTT1, GSTA1 and GSTP1 polymorphisms might be associated with the risk of cRCC, with special emphasis on GSTM1-null and GSTP1-variant genotypes. Combined GSTM1-null, GSTT1-active, GSTA1 low activity and GSTP1-variant genotypes might be considered as "risk-carrying genotype combination" in cRCC.

  15. The glutathione-S-transferase mu 1 (GSTM1) null genotype and increased neutrophil response to low-level ozone (0.06 ppm).

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    Background: Exposure of healthy young adults to 03 modulates immune cell biology in the airways and causes a significant increase in neutrophilic inflammation which can vary considerably in magnitude across individuals. The GSTM1null genotype modulates Oj-induced inflammation, bu...

  16. The glutathione-S-transferase mu 1 (GSTM1) null genotype and increased neutrophil response to low-level ozone (0.06 ppm).

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    Background: Exposure of healthy young adults to 03 modulates immune cell biology in the airways and causes a significant increase in neutrophilic inflammation which can vary considerably in magnitude across individuals. The GSTM1null genotype modulates Oj-induced inflammation, bu...

  17. No association between GSTM1 and GSTT1 genetic polymorphisms and susceptibility to opium sap dependence.

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    Saify, Khyber; Khalighinasab, Mohammad Rashid; Saadat, Mostafa

    2016-03-01

    Glutathione S-transferases (GSTs; EC: 2.5.1.18) are a ubiquitous family of eukaryotic and prokaryotic phase II metabolic isozymes. Genes encoding GSTM1 (OMIM: 138350), and GSTT1 (OMIM: 600436) are members of class mu and theta, respectively. The most common polymorphism in the GSTM1 is a deletion of the whole GSTM1 gene with a lack of enzyme activity. A homozygous deletion in the GSTT1 has also been reported (null genotypes of GSTT1). The aim of the present study was to investigate the association between GSTM1 and GSTT1 polymorphisms and risk of dependency to opium sap. The present study was performed in Shiraz (southern Iran). In total, 71 males dependent to opium sap and 590 healthy males (as a control group) were included in this study. The genotypes of GSTM1 and GSTT1 polymorphisms were determined by PCR. Our data indicate that neither GSTM1 (OR=0.78, 95% CI: 0.47-1.27, P=0.325) nor GSTT1 (OR=1.25, 95% CI: 0.70-2.21, P=0.442) null genotypes significantly associated with the risk of opium sap dependence. There is no additive effect of the null genotypes of GSTT1 and GSTM1 in relation to the risk of dependency to opium sap. The present study indicated that the null genotypes of GSTT1 and GSTM1 are not risk factor for opium sap dependence.

  18. GSTT1 Null Genotype Is a Risk Factor for Diabetic Retinopathy in Caucasians with Type 2 Diabetes, whereas GSTM1 Null Genotype Might Confer Protection against Retinopathy

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    Ines Cilenšek

    2012-01-01

    Full Text Available Aim: Substantial data indicate that oxidative stress is involved in the development of diabetic retinopathy (DR. The aim of the present study was to investigate whether the genetic polymorphisms: polymorphic deletions of glutathione S-transferases M1 (GSTM1 and T1 (GSTT1 and Ile105Val of the GSTP1 are associated with DR in Slovenian patients with type 2 diabetes.

  19. Correlation of CYP1A1 and GSTM1 gene polymorphisms and environmental factors to familial aggregation of esophageal cancer among the Kazakh ethnic group in Xinjiang.

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    Zeng, M; Lv, Y; Wang, H F; Yiguli, H A; Zhang, J R; Yisikandaer, A

    2015-12-29

    This study aimed to investigate the correlation of CYP1A1 and GSTM1 gene polymorphisms and environmental factors to familial aggregation of esophageal cancer (EC) among the Kazakh ethnic group in Xinjiang. CYP1A1 and GSTM1 gene polymorphisms were detected using peripheral blood from 86 subjects belonging to families with EC and 82 control subjects. Additionally, a questionnaire survey was conducted to ascertain environmental risk factors. Combined effects of CYP1A1 and GSTM1 gene polymorphisms and environmental factors in familial aggregation of EC were evaluated. Distribution frequencies of CYP1A1 MspI and GSTM1 genotypes between EC and control families showed significant differences (P = 0.002, P = 0.001). Contribution of interaction between CYP1A1 MspI mutant and GSTM1 deletion polymorphisms to familial aggregation of EC was significant, with OR = 3.571 (95%CI = 1.738-3.346). Logistic multivariate analysis indicated that familial aggregation of EC is correlated with 3 factors: drinking water, intake of fresh vegetables and fruits, and CYP1A1 MspI polymorphism (P = 0.005, P = 0.013, and P = 0.001). Sufficient intake of fresh vegetables and fruits (OR = 0.278, 95%CI = 0.137-0.551) protected against familial aggregation of EC, while drinking water (OR = 3.468, 95%CI = 1.562-6.551) and CYP1A1 MspI polymorphism (OR = 2.732, 95%CI = 1.741-3.886) were the risk factors. In conclusion, CYP1A1 and GSTM1 gene polymorphisms affect familial aggregation of EC among the Kazakh ethnic group in Xinjiang. River water intake and CYP1A1 MspI polymorphism were risk factors that likely contributed to high incidence of EC among families.

  20. GSTM1 and XRCC3 Polymorphisms: Effects on Levels of Aflatoxin B1-DNA Adducts

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    Xi-dai Long; Yun Ma; Zhou-lin Deng

    2009-01-01

    Objective: Aflatoxin B1 (AFB1), which can cause the formation of AFB1-DNA adducts, is a known human carcinogen. AFB1-exposure individuals with inherited susceptible carcinogen-metabolizing or repairing genotypes may experience an increased risk of genotoxicity. This study was designed to investigate whether the polymorphisms of two genes, the metabolic gene Glutathione S-transferase M1 (GSTM1) and DNA repair gene x-ray repair cross-complementing group 3 (XRCC3), can affect the levels of AFB1-DNA adducts in Guangxi Population (n= 966) from an AFB1-exposure area.Methods: AFB1-DNA adducts were measured by ELISA, and GSTM1 and XRCC3 codon 241 genotypes were identified by PCR-RFLP.Results: The GSTM1-null genotype [adjusted odds ratio (OR) = 2.09; 95% confidence interval (CI) = 1.61(2.71] and XRCC3 genotypes with 241 Met alleles [i.e., XRCC3-TM and -MM, adjusted ORs (95% CI) were 1.43 (1.08(1.89) and 2.42 (1.13(5.22), respectively] were significantly associated with higher levels of AFB1-DNA adducts. Compared with those individuals who did not express any putative risk genotypes as reference (OR = 1), individuals featuring all of the putative risk genotypes did experience a significantly higher DNA-adduct levels (adjusted ORs were 2.87 for GSTM1-null and XRCC3-TM; 5.83 for GSTM1-null and XRCC3-MM). Additionally, there was a positive joint effect between XRCC3 genotypes and long-term AFB1 exposure in the formation of AFB1-DNA adducts.Conclusion: These results suggest that individuals with susceptible genotypes GSTM1-null, XRCC3-TM, or XRCC3-MM may experience an increased risk of DNA damage elicited by AFB1 exposure.

  1. GSTT1,GSTM 1 and CYP2E1 genetic polymorphisms in gastric cancer and chronic gastritis in a Brazilian population

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    Jucimara Colombo; Andréa Regina Baptista Rossit; Alaor Caetano; Aldenis Albaneze Borim; Durval Wornrath; Ana Elizabete Silva

    2004-01-01

    AIM: To test the hypothesis that, in the Southeastern Brazilian population, the GSTT1, GSTM1 and CYP2E1polymorphisms and putative risk factors are associated with an increased risk for gastric cancer.METHODS: We conducted a study on 100 cases of gastric cancer (GC), 100 cases of chronic gastritis (CG), and 150controls (C). Deletion of the GSTT1 and GSTM1 genes was assessed by multiplex PCR. CYP2E1/PstI genotyping was performed using a PCR-RFLP assay.RESULTS: No relationship between GSTT1/GSTM1 deletion and the c1/c2 genotype of CYP2E1 was observed among the three groups. However, a significant difference between CG and C was observed, due to a greater number of GSTT1/GSTM1 positive genotypes in the CG group. The GSTT1 null genotype occurred more frequently in Negroid subjects, and the GSTM1 null genotype in Caucasians, while the GSTM1 positive genotype was observed mainly in individuals with chronic gastritis infected with H pylori.CONCLUSION: Our findings indicate that there is no obvious relationship between the GSTT1, GSTM1 and CYP2E1 polymorphisms and gastric cancer.

  2. Association between primary open angle glaucoma and genetic polymorphisms GSTM1/GSTT1 in patients from Goiânia Central-West Region of Brazil.

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    Silva, C T X; Costa, N B; Silva, K S F; Silva, R E; Moura, K K V O

    2014-10-31

    In this study, we evaluated the genotype profile of GSTM1 and GSTT1 polymorphisms in patient carriers of primary open-angle glaucoma in the population of Goiânia, GO, Brazil. This case-control study included 100 Brazilian patients with glaucoma and 53 patients without glaucoma. Blood samples were genotyped for polymorphisms in GST genes using polymerase chain reaction-based methods. Polymorphism frequencies were compared using the X(2) test and odds ratio (α = 0.05). The GSTM1-present genotype was 40% in the glaucoma group and 71.6% in the control group, while the GSTM1 null genotype was 60 and 28.3% in the same groups, respectively. The GSTT1-present genotype was 52% in the primary open-angle glaucoma group and 66% in the control group; the null genotype was 48% in the case group and 34% in the control group. The GSTM1 null genotype was more frequent in the glaucoma group than in the control group (P = 0.0004; odds ratio = 6.7; 95% confidence interval = 2.7- 20.3). The combined GSTM1 null and GSTT1-present genotypes were more frequent in the primary open-angle glaucoma group compared to the control group (P = 0.02; odds ratio = 3.1; 95% confidence interval = 1.2-7.9).

  3. Low level maternal smoking and infant birthweight reduction: genetic contributions of GSTT1 and GSTM1 polymorphisms.

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    Danileviciute, Asta; Grazuleviciene, Regina; Paulauskas, Algimantas; Nadisauskiene, Ruta; Nieuwenhuijsen, Mark J

    2012-12-26

    Genetic susceptibility to tobacco smoke might modify the effect of smoking on pregnancy outcomes. We conducted a case-control study of 543 women who delivered singleton live births in Kaunas (Lithuania), examining the association between low-level tobacco smoke exposure (mean: 4.8 cigarettes/day) during pregnancy, GSTT1 and GSTM1 polymorphisms and birthweight of the infant. Multiple linear-regression analysis was performed adjusting for gestational age, maternal education, family status, body mass index, blood pressure, and parity. Subsequently, we tested for the interaction effect of maternal smoking, GSTT1 and GSTM1 genes polymorphisms with birthweight by adding all the product terms in the regression models. The findings suggested a birthweight reduction among light-smoking with the GSTT1-null genotype (-162.9 g, P = 0.041) and those with the GSTM1-null genotype (-118.7 g, P = 0.069). When a combination of these genotypes was considered, birthweight was significantly lower for infants of smoking women the carriers of the double-null genotypes (-311.2 g, P = 0.008). The interaction effect of maternal smoking, GSTM1 and GSTT1 genotypes was marginally significant on birthweight (-234.5 g, P = 0.078). Among non-smokers, genotype did not independently confer an adverse effect on infant birthweight. The study shows the GSTT1-null genotype, either presents only one or both with GSTM1-null genotype in a single subject, have a modifying effect on birthweight among smoking women even though their smoking is low level. Our data also indicate that identification of the group of susceptible subjects should be based on both environmental exposure and gene polymorphism. Findings of this study add additional evidence on the interplay among two key GST genes and maternal smoking on birth weight of newborns.

  4. Glutathione S-transferase mu 1 (GSTM1 and theta 1 (GSTT1 genetic polymorphisms and atopic asthma in children from Southeastern Brazil

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    Carmen Silvia Passos Lima

    2010-01-01

    Full Text Available Xenobiotics can trigger degranulation of eosinophils and mast cells. In this process, the cells release several substances leading to bronchial hyperactivity, the main feature of atopic asthma (AA. GSTM1 and GSTT1 genes encode enzymes involved in the inactivation of these compounds. Both genes are polymorphic in humans and have a null variant genotype in which both the gene and corresponding enzyme are absent. An increased risk for disease in individuals with the null GST genotypes is therefore, but this issue is controversial. The aim of this study was to investigate the influence of the GSTM1 and GSTT1 genotypes on the occurrence of AA, as well as on its clinical manifestations. Genomic DNA from 86 patients and 258 controls was analyzed by polymerase chain reaction. The frequency of the GSTM1 null genotype in patients was higher than that found in controls (60.5% versus 40.3%, p = 0.002. In individuals with the GSTM1 null genotype the risk of manifested AA was 2.3-fold higher (95%CI: 1.4-3.7 than for others. In contrast, similar frequencies of GSTT1 null and combined GSTM1 plus GSTT1 null genotypes were seen in both groups. No differences in genotype frequencies were perceived in patients stratified by age, gender, ethnic origin, and severity of the disease. These results suggest that the inherited absence of the GSTM1 metabolic pathway may alter the risk of AA in southeastern Brazilian children, although this must be confirmed by further studies with a larger cohort of patients and age-matched controls from the distinct regions of the country.

  5. Genotype and allele frequencies of isoniazid-metabolizing enzymes NAT2 and GSTM1 in Latvian tuberculosis patients.

    Science.gov (United States)

    Igumnova, Viktorija; Capligina, Valentina; Krams, Alvils; Cirule, Andra; Elferts, Didzis; Pole, Ilva; Jansone, Inta; Bandere, Dace; Ranka, Renate

    2016-07-01

    Pharmacogenomic testing of tuberculosis drug-metabolizing enzyme genes was proposed as a strategy to identify patients at risk for suboptimal responses to medications. However, variations of the genotype frequencies among ethnic groups exist and new alleles are been identified. The aim of this study was to identify polymorphisms of genes encoding metabolic enzymes NAT2 and GSTM1 in tuberculosis patients in Latvia and to estimate the frequency of NAT2 slow acetylator and GSTM1 null genotypes. In total, 85 DNA samples were genotyped, all individuals were Caucasian. An ethnic heterogeneity reflecting the multiethnic population of the country was observed. 49 patients were Latvians, 30 were Russians and 6 of other ethnicity. In total, 7 NAT2 alleles were identified: *4, *5, *6, *7, *11, *12, * and *13. The most frequent was the slow acetylation allele NAT2*6 (frequency 0.388) followed by the slow acetylation allele NAT2*5 and the rapid acetylation allele NAT2*4 (frequencies 0.306 and 0.194, respectively). The predominance of slow (51.8%) and intermediate (43.5%) acetylators compared with rapid acetylators (4.7%) was observed. The GSTM1 null genotype was detected in 48.2% of tuberculosis patients. When subgroup analysis was performed according to ethnicity, the results showed that neither NAT2 allele frequencies nor GSTM1 null genotype frequency did not differ significantly in TB patients of Latvian or Russian ethnicity. Overall, genotyping results were similar with previous reports of a NAT2 gene variation and GSTM1 null genotype frequency in Caucasians. Our findings have a contribution for the pharmacogenetics-based tuberculosis therapy in Latvia in future.

  6. Association between GSTM1 and GSTT1 allelic variants and head and neck squamous cell cancinoma.

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    Yang Zhang

    Full Text Available BACKGROUNDS: GSTM1 and GSTT1 are involved in the detoxification of carcinogens such as smoking by-products, and polymorphisms in these two genes with a result of loss of enzyme activity may increase risk of carcinogenesis. Although many epidemiological studies have investigated the association between GSTM1 or GSTT1 null genotype and head and neck squamous cell carcinoma (HNSCC, the results remain conflicting. To elucidate the overall association of GSTM1, GSTT1 and HNSCC, we included all available studies and performed this meta-analysis. METHODOLOGY/PRINCIPAL FINDINGS: A dataset including 42 articles for GSTM1, 32 articles for GSTT1, and 15 articles for GSTM1 and GSTT1 in combination were identified by a search in PubMed. Associations beween HNSCC and polymorphisms of GSTM1 and GSTT1 alone and in combination were analysed by software RevMan 5.1. Stratification analysis on ethnicity and smoking status, sensitivity analysis, heterogeneity among studies and their publication bias were also tested. Association was found in overall analysis between HNSCC and GSTM1 and GSTT1 null genotype. Stratified by ethnicity, we found increased risks of HNSCC in carriers with GSTM1 null genotype in Asian, GSTT1 null genotype in South American, and dual null genotype in European and Asian. When stratified by smoking, a more significant association of GSTM1 null genotype with HNSCC risk was observed in smokers. CONCLUSIONS/SIGNIFICANCE: This meta-analysis presented additional evidence of the association between GSTM1 and GSTT1 polymorphisms and HNSCC risk.

  7. Droplet Digital PCR Analysis of GSTM1 Deletion Polymorphism in Psoriatic Subjects Treated with Goeckerman Therapy

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    Martin Beránek

    2016-08-01

    Full Text Available Goeckerman therapy (GT represents an effective treatment of psoriasis including a combination of pharmaceutical grade crude coal tar (CCT and ultraviolet irradiation (UV-R. Coal tar contains a mixture of polycyclic aromatic hydrocarbons. The best known carcinogenic polyaromate – benzo[a]pyrene is metabolized into a highly reactive benzo[a]pyrene-7,8-diol-9,10-epoxide (BPDE. Glutathione S-transferase M1 (GSTM1 catalyses the conjugation of drugs, toxins and products of oxidative stress with glutathione. The aim of the study is to found possible associations between GSTM1 genotypes and the level of BPDE-DNA adducts in 46 psoriatic patients treated with GT. For genotyping, droplet digital PCR was applied. The GSTM1 copy number was normalized to β-globin reference gene. In five GSTM1*1/*1 subjects, the GSTM1 to β-globin ratio moved from 0.99 to 1.03 with a median of 1.01. GSTM1*0/*1 heterozygotes (n = 20 contained only one GSTM1 function allele which conditioned the ratio 0.47–0.53 (median 0.50. GSTM1*0/*0 individuals (n = 21 showed no amplification of the null variants because of the large deletion in GSTM1. BPDE-DNA concentrations ranged from 1.8 to 66.3 ng/µg with a median of 12.3 ng/µg. GSTM1*0/*0 and GSTM1*0/*1 genotypes showed non-significantly higher concentrations of BPDE-DNA adducts than the GSTM1*1/*1 one (12.3 and 12.4 vs 7.8 ng/µg. The non-significant relationship between BPDE-DNA adducts and GSTM1 genotypes in psoriatic patients could be associated with relatively low doses of CCT and short-term UV-R exposures used in GT.

  8. Meta-analysis of association between GSTM1 gene polymorphism and cervical cancer

    Institute of Scientific and Technical Information of China (English)

    Ying Liu; Liang-Zhi Xu

    2012-01-01

    Objective:To investigate association between glutathione S-transferases (GSTs) and cervical cancer.Methods:Published literature from PubMed, EMBASE, and other databases were retrieved. All studies evaluating the association betweenGSTM1/GSTT1 polymorphisms and cervical were included. Pooled odds ratio (OR) and95% confidence interval (CI) were calculated using fixed- or random-effects model.Results:A total of15 case-control studies were included in the meta-analysis of GSTM1 genotypes (1 825 cases and2 104 controls). The overall result showed that the association betweenGSTM1 null genotype and risk for cervical cancer was statistically significant (OR=1.53, 95%CI=1.18-2.00). Great heterogeneity was found between studies. Subgroup analysises were performed based on smoking and ethnicity. Our results showed that smokers with nullGSTM1 genotype had higher risk of cervical cancer (OR=1.56,95%CI=1.01-2.41). For the ethnicity stratification, significant increased risk of nullGSTM1 genotype was found in Chinese and Indian population, but no increased risk in other population.Conclusions:This meta-analysis provides strong evidence that theGSTM1 null genotype is associated with the development of cervical cancer, and especially in Chinese and Indian population, and smoking shows a modification on the association between GSTM1 null genotype and cervical cancer.

  9. CYP1A1, GSTM1, GSTT1 and TP53 Polymorphisms and Risk of Gallbladder Cancer in Bolivians.

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    Sakai, Kazuaki; Loza, Ernesto; Roig, Guido Villa-Gomez; Nozaki, Ryoko; Asai, Takao; Ikoma, Toshikazu; Tsuchiya, Yasuo; Kiyohara, Chikako; Yamamoto, Masaharu; Nakamura, Kazutoshi

    2016-01-01

    The Plurinational State of Bolivia (Bolivia) has a high incidence rate of gallbladder cancer (GBC). However, the genetic and environmental risk factors for GBC development are not well understood. We aimed to assess whether or not cytochrome P450 (CYP1A1), glutathione S-transferase mu 1 (GSTM1), theta 1 (GSTT1) and tumor suppressor protein p53 (TP53) genetic polymorphisms modulate GBC susceptibility in Bolivians. This case-control study covered 32 patients with GBC and 86 healthy subjects. GBC was diagnosed on the basis of histological analysis of tissues at the Instituto de Gastroenterologia Boliviano-Japones (IGBJ); the healthy subjects were members of the staff at the IGBJ. Distributions of the CYP1A1 rs1048943 and TP53 rs1042522 polymorphisms were assayed using PCR-restriction fragment length polymorphism assay. GSTM1 and GSTT1 deletion polymorphisms were detected by a multiplex PCR assay. The frequency of the GSTM1 null genotype was significantly higher in GBC patients than in the healthy subjects (odds ratio [OR], 2.35; 95% confidence interval [CI], 1.03-5.37; age-adjusted OR, 3.53; 95% CI, 1.29-9.66; age- and sex-adjusted OR, 3.40; 95% CI, 1.24-9.34). No significant differences were observed in the frequencies of CYP1A1, GSTT1, or TP53 polymorphisms between the two groups. The GSTM1 null genotype was associated with increased GBC risk in Bolivians. Additional studies with larger control and case populations are warranted to confirm the association between the GSTM1 deletion polymorphism and GBC risk suggested in the present study.

  10. Genotype frequencies of polymorphic GSTM1, GSTT1, and cytochrome P450 CYP1A1 in Mexicans.

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    Montero, Regina; Araujo, Antonio; Carranza, Paloma; Mejía-Loza, Vanessa; Serrano, Luis; Albores, Arnulfo; Salinas, Juan E; Camacho-Carranza, Rafael

    2007-06-01

    The genotype frequencies of three metabolic polymorphisms were determined in a sample of a typical community in central Mexico. CYP1A1*3, GSTM1, and GSTT1 polymorphisms were studied in 150 donors born in Mexico and with Mexican ascendants; with respect to ethnicity the subjects can be considered Mestizos. PCR reactions were used to amplify specific fragments of the selected genes from genomic DNA. An unexpected 56.7% frequency of the CYP1A1*3 allele (which depends on the presence of a Val residue in the 462 position of the enzyme, instead of Ile) was found, the highest described for open populations of different ethnic origins (i.e., Caucasian, Asian, African, or African American). The GSTM1 null genotype was found with a frequency of 42.6%, which is not different from other ethnicities, whereas the GSTT1 null genotype had a frequency of 9.3%, one of the lowest described for any ethnic group but comparable to the frequency found in India (9.7%). The frequency of the combined genotype CYP1A1*3/*3 and the GSTM1 null allele is one of the highest observed to date (or perhaps the highest): 13.7% among all the ethnicities studied, including Caucasians and Asians, whereas the combination of CYP1A1*3/*3 with the GSTT1 null allele reached only 2.8%. The GSTM1 null allele combined with the GSTT1 null allele, on the other hand, has one of the lowest frequencies described, 4.24%, comparable to the frequencies found in African Americans and Indians. Finally, the combined CYP1A1*3/*3, GSTM1 null allele, and GSTT1 null allele genotype could not be found in the sample studied; it is assumed that the frequency of carriers of these combined genotypes is less than 1%. CYP1A1*3 and CYP1A1*2 polymorphisms were also evaluated in 50 residents in a community of northern Mexico; the CYP1A1*3 frequency was 54%, similar to that found in the other community studied, and the CYP1A1*2 frequency was 40%, which is high compared to Caucasians and Asians but comparable to the frequency found in

  11. Ethnicity and glutathione S-transferase (GSTM1/GSTT1 polymorphisms in a Brazilian population

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    G.J.F. Gattás

    2004-04-01

    Full Text Available The distribution of polymorphisms related to glutathione S-transferases (GST has been described in different populations, mainly for white individuals. We evaluated the distribution of GST mu (GSTM1 and theta (GSTT1 genotypes in 594 individuals, by multiplex PCR-based methods, using amplification of the exon 7 of CYP1A1 gene as an internal control. In São Paulo, 233 whites, 87 mulattos, and 137 blacks, all healthy blood-donor volunteers, were tested. In Bahia, where black and mulatto populations are more numerous, 137 subjects were evaluated. The frequency of the GSTM1 null genotype was significantly higher among whites (55.4% than among mulattos (41.4%; P = 0.03 and blacks (32.8%; P < 0.0001 from São Paulo, or Bahian subjects in general (35.7%; P = 0.0003. There was no statistically different distribution among any non-white groups. The distribution of GSTT1 null genotype among groups did not differ significantly. The agreement between self-reported and interviewer classification of skin color in the Bahian group was low. The interviewer classification indicated a gradient of distribution of the GSTM1 null genotype from whites (55.6% to light mulattos (40.4%, dark mulattos (32.0% and blacks (28.6%. However, any information about race or ethnicity should be considered with caution regarding the bias introduced by different data collection techniques, specially in countries where racial admixture is intense, and ethnic definition boundaries are loose. Because homozygous deletions of GST gene might be associated with cancer risk, a better understanding of chemical metabolizing gene distribution can contribute to risk assessment of humans exposed to environmental carcinogens.

  12. Genetic Polymorphism in Glutathione Transferases (GST): Population distribution of GSTM1, T1, and P1 conjugating activity.

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    Ginsberg, Gary; Smolenski, Susan; Hattis, Dale; Guyton, Kathryn Z; Johns, Douglas O; Sonawane, Babasaheb

    2009-01-01

    Glutathione transferases (GST) catalyze the conjugation of glutathione (GSH) with electrophiles, many of which may otherwise interact with protein or DNA. In select cases such as halogenated solvents, GST-mediated conjugation may lead to a more toxic or mutagenic metabolite. Polymorphisms that exert substantial effects on GST function were noted in human populations for several isozymes. This analysis focuses on three well-characterized isozymes, GSTM1, T1, and P1, in which polymorphisms were extensively studied with respect to DNA adducts and cancer in molecular epidemiologic studies. The current review and analysis focused upon how polymorphisms in these GST contributed to population variability in GST function. The first step in developing this review was to characterize the influence of genotype on phenotype (enzyme function) and the frequency of the polymorphisms across major population groups for all three GST. This information was then incorporated into Monte Carlo simulations to develop population distributions of enzyme function. These simulations were run separately for GSTM1, T1, and P1, and also for the combination of these isozymes, to assess the possibility of overlapping substrate specificity. Monte Carlo simulations indicated large interindividual variability for GSTM1 and T1 due to the presence of the null (zero activity) genotype, which is common in all populations studied. Even for GSTM1 or T1 non-null individuals, there was considerable interindividual variability with a bimodal distribution of enzyme activity evident. GSTP1 polymorphisms are associated with somewhat less variability due to the absence of null genotypes. However, in all cases simulated, the estimated variability is sufficiently large to warrant consideration of GST function distributions in assessments involving GST-mediated activation or detoxification of xenobiotics. Ideally, such assessments would involve physiologically based toxicokinetic (PBTK) modeling to assess

  13. Combination Effect of GSTM1, GSTT1 and GSTP1 Polymorphisms and Risk of Systemic Lupus Erythematosus

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    Saeedeh SALIMI

    2015-10-01

    Full Text Available Background: Progression of systemic lupus erythematosus (SLE could be due to oxidative stress especially through reactive oxygen species (ROS. Detoxification of ROS is largely performed by Glutathione S-transferases (GSTs, therefore polymorphisms of GSTM1, GSTT1 and GSTP1 genes which decrease enzymes activity could affect SLE susceptibility. The aim of this study was to determine the effects of GSTM1 (deletion, GSTT1 (deletion and GSTP1 (Ile105Val polymorphisms on SLE susceptibility.Methods: Genomic DNA was extracted from blood samples of 163 SLE patients and 180 age, sex and ethnically matched controls. GSTs genotypes were determined by polymerase chain reaction (PCR-multiplex procedure or pol-ymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP analysis.Results: GSTT1 null genotype frequency was higher in SLE patients than controls. NO association observed between GSTM1 null genotype or GSTP1 Ile105Val polymorphism with SLE. Nevertheless combination of GSTT1 null/ GSTM1 null genotypes showed 2.8-fold increase in risk of SLE. Moreover the combination of GSTT1 null/ GSTM1 null/GSTP1 Ile/Val and Val/Val genotypes increased the SLE risk about 8 fold.Conclusion: Present data suggest that GSTT1 null/ GSTM1 null/GSTP1 Ile/Val and Val/Val genotypes might large-ly contribute to the pathogenesis of SLE.

  14. 自发性不育男性中谷胱甘肽S转移酶Mu-1基因的缺失使其精子和精浆的氧化损伤程度增加%Increased oxidative damage of sperm and seminal plasma in men with idiopathic infertility is higher in patients with glutathione S-transferase Mu-1 null genotype

    Institute of Scientific and Technical Information of China (English)

    B.Aydemir; I.Onaran; A.R.Kiziler; B.Alici; M.C.Akyolcu

    2007-01-01

    Aim:To examine whether a relationship exists between glutathione S-transferase Mu-1 (GSTM1) gene polymorphism and the susceptibility of sperm and seminal plasma from patients with idiopathic infertility to oxidative stress.Methods: Fifty-two men with idiopathic infertility and 60 healthy fertile men were recruited to this study. GSTM1 gene polymorphism was determined by polymerase chain reaction (PCR) and both the infertile and control individuals were divided into GSTM1 null and GSTM1 positive groups according to their GSTM1 gene structure. We compared reactive oxygen species (ROS) generation, malondialdehyde (MDA), protein carbonyls and glutathione (GSH) concentrations, and glutathione S-transferase (GST) activity in seminal plasma and spermatozoa from infertile patients and controls with respect to GSTM1 genotype. Results: Significantly higher levels of oxidative stress and damage markers were found in idiopathic infertile men with the GSTM1 null genotype compared with those with the GSTM1 positive genotype. There was no significant difference in genotype distribution for the GSTM1 variant between the idiopathic infertile subjects and fertile subjects. Patients with the GSTM1 null genotype also had lower sperm concentrations than those with GSTM1 positive genotype. Conclusion: Our results suggest that the susceptibility of sperm and seminal plasma to oxidative stress is significantly greater in idiopathic infertile men with the GSTM1 null genotype compared with those possessing the gene. Therefore, in patients with idiopathic infertility,GSTM1 polymorphism might be an important source of variation in susceptibility of spermatozoa to oxidative damage.

  15. Associations of GSTM1*0 and GSTA1*A genotypes with the risk of cardiovascular death among hemodialyses patients.

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    Suvakov, Sonja; Damjanovic, Tatjana; Pekmezovic, Tatjana; Jakovljevic, Jovana; Savic-Radojevic, Ana; Pljesa-Ercegovac, Marija; Radovanovic, Slavica; Simic, Dragan V; Pljesa, Steva; Zarkovic, Milos; Mimic-Oka, Jasmina; Dimkovic, Nada; Simic, Tatjana

    2014-01-14

    The presence of glutathione transferase (GST) M1 null genotype (GSTM1-null) in end-stage renal disease (ESRD) patients is associated with lower overall survival rate in comparison to those with GSTM1-active variants. We examined association between GSTM1 and GSTT1 deletion polymorphisms as well as SNPs in GSTA1/rs3957357 and GSTP1/rs1695 genes with overall and cause-specific cardiovascular mortality in ESRD patients. Total of 199 patients undergoing hemodialysis were included in the study. Median value of time elapsed from dialysis initiation until the death, or the end of follow-up was 8 ± 5 years. The effect of GSTM1, GSTT1, GSTP1 and GSTA1 gene polymorphisms on predicting overall and specific cardiovascular outcomes (myocardial infarction, MI or stroke) was analyzed using Cox regression model, and differences in survival were determined by Kaplan-Meier. GSTM1-null genotype in ESRD patients was found to be independent predictor of overall and cardiovascular mortality. However, after false discovery rate and Bonferroni corrections this effect was lost. The borderline effect modification by wild-type GSTA1*A/*A genotype on associations between GSTM1-null and analyzed outcomes was found only for death from stroke. Homozygous carriers of combined GSTM1*0/GSTA1*A genotype exhibited significantly shorter time to death of stroke or MI in comparison with carriers of either GSTM1-active or at least one GSTA1*B gene variant. The best survival rate regarding cardiovascular outcome was found for ESRD patients with combined GSTM1-active and mutant GSTA1*B/*B genotype. Combined GSTM1*0/GSTA1*A genotypes might be considered as genetic markers for cardiovascular death risk in ESRD patients, which may permit targeting of preventive and early intervention.

  16. GSTT1 and GSTM1 gene polymorphisims in sarcoidosis.

    Science.gov (United States)

    Coskun, Funda; Karkucak, Mutlu; Yilmaz, Dilber; Yakut, Tahsin; Uzaslan, Esra

    2016-10-07

    Sarcoidosis is a granulomatous disease of unknown cause, which affects all systems, especially the lungs and the lymphatic system. Genetic and environmental factors are held accountable for the etiology. Based on the general opinion, sarcoidosis develops after exposure to a specific environmental agent by genetically susceptible individuals.  The present study aimed to evaluate the disease susceptibility of the GSTT1 and GSTM1 gene polymorphisms in the patients with sarcoidosis. The present study included 78 patients; 38 patients with histopathologically verified sarcoidosis and 40 control subjects. Multiplex PCR method was used to determine the GSTT1 and GSTM1 gene polymorphisms. The genotype was determined based on the bands formed in the agarose gel electrophoresis. The statistical analysis was done using the chi-square test. The positive/negative genotype rates were 79%/21% and 53%/47%, respectively in the case group for the GSTT1 and GSTM1 gene polymorphisms, whereas the positive/negative genotype rates were 77%/23% and 55%/45% in the control group. There was no statistically significant difference in the positive and negative genotypes compared with the case group and the control group for the GSTT1 and GSTM1 gene polymorphisms (p > 0.05). The results from the present study suggest that there is not any association with the control group for the disease susceptibility of the GSTT1 and GSTM1 gene polymorphisms in patients with sarcoidosis, and this result should be supported by large-scale studies because of the limited number of cases in the present study.

  17. Glutathione S-transferase gene polymorphisms (GSTM1, GSTT1, and GSTP1) in Egyptian pediatric patients with sickle cell disease.

    Science.gov (United States)

    Shiba, Hala Fathy; El-Ghamrawy, Mona Kamal; Shaheen, Iman Abd El-Mohsen; Ali, Rasha Abd El-Ghani; Mousa, Somaia Mohammed

    2014-01-01

    Sickle cell disease (SCD) complications are associated with oxidative stress. Glutathione S-transferases (GSTs) are a group of enzymes that protect against oxidative stress. The aims of this study was to evaluate the prevalence of GSTM1, GSTT1, and GSTP1 gene polymorphisms among homozygous sickle cell anemia patients and to investigate the possible association between the presence of these polymorphisms and SCD severity and complications. Genotyping the polymorphisms in GSTT1 and GSTM1 genes was performed using the multiplex polymerase chain reaction (PCR) method. The GSTP1 ILe105Val polymorphism was determined using PCR-restriction fragment length polymorphism. GSTM1 null genotype was significantly associated with increased risk of severe vaso-occlusive crises (VOC) (odds ratio  =  1.52, 95% confidence interval  =  0.42-5.56, P  =  0.005). We found no significant association between GST genotypes and frequency of sickle cell-related pain, transfusion frequency, disease severity, or hydroxyurea treatment. GSTM1 gene polymorphism may be associated with risk of severe VOC among Egyptian SCD patients.

  18. Association of glutathione S-transferase polymorphisms (GSTM1 and GSTT1) with primary open-angle glaucoma: an evidence-based meta-analysis.

    Science.gov (United States)

    Huang, Wenbin; Wang, Wei; Zhou, Minwen; Chen, Shida; Zhang, Xiulan

    2013-09-10

    Studies investigating the associations between glutathione S-transferase (GST) genetic polymorphisms and primary open-angle glaucoma (POAG) have reported controversial results. Therefore, a meta-analysis was performed to clarify the effects of GSTM1 and GSTT1 polymorphisms on POAG risk. Published literatures from PubMed, EMBASE, ISI Web of Science and CBM databases were retrieved. All studies evaluating the association between GSTM1/GSTT1 polymorphisms and POAG were included. Pooled odds ratio (OR) and 95% confidence interval (CI) were calculated using fixed- or random-effects model. Eleven studies on GSTM1 (1339 cases and 1412 controls) and seven studies on GSTT1 (958 cases, 1003 controls) were included. Overall analysis showed that the association between GSTM1 and GSTT1 null genotype and POAG risk is not statistically significant. Subgroup analyses showed that the null genotype of GSTM1 increased the risk of POAG in Asians. In GSTM1-GSTT1 interaction analysis, individuals with dual null genotype were associated with a significantly increased risk of POAG when compared with the dual present genotype. In conclusion, the present meta-analysis suggested that GSTM1 null genotypes are associated with increased POAG risk in Asian populations but not in Caucasian and mixed populations. Dual null genotype of GSTM1/GSTT1 is associated with increased risk of POAG. Given the limited sample size, the finding on GST polymorphisms needs further investigation.

  19. Polimorfismos GSTT1 e GSTM1 em indivíduos tabagistas com carcinoma espinocelular de cabeça e pescoço GSTT1 and GSTM1 polymorphism in cigarette smokers with head and neck squamous cell carcinoma

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    Joice Matos Biselli

    2006-10-01

    . The GSTT1 null genotype was found in 33.3% of the Experimental Group and 23.3% of the Control Group (p= 0.311. Experimental and Control Groups had GSTM1 null genotype frequencies of 35% and 48.3% (p=0.582. No association between alcohol consumption and GSTT1 and GSTMI null genotypes was found in these groups (p-values>0.05. There were more men, and alcohol consumption was prevalent in both groups. CONCLUSION: In this study we were unable to show a correlation between GSTM1 and GSTT1 genotypes and the development of head and neck squamous cell carcinomas in cigarette smokers.

  20. Nullity of GSTT1/GSTM1 related to pesticides is associated with Parkinson's disease

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    Marcela Augusta de Souza Pinhel

    2013-08-01

    Full Text Available Genetic and environmental factors affect the pathogenesis of Parkinson's disease (PD. Genetic variants of the enzyme glutathione S-transferases (GST may be related to the disease. This study aimed to evaluate the influence of genetic variants of GST (GSTT1/GSTM1 and their association with the exposure to environmental toxins in PD patients. We studied 254 patients with PD and 169 controls. The GSTM1/GSTT1 variants were analyzed by polymerase chain reaction. We applied the Fisher's exact test and the χ2 test for statistical analysis (p<0.05. The present and absence for GSTT1 and GSTM1 were similar in patients and controls. The null for GSTT1 and GSTM1 (0/0 and exposure to pesticides prevailed in patients (18% compared to controls (13%, p=0.014. This study suggests the association between PD and previous exposure to pesticides, whose effect may be enhanced in combination with null for GSTT1/GSTM1.

  1. 甲母痣恶变易感性与谷胱苷肽S转移酶M1、谷胱苷肽S转移酶T1基因缺失的关系%Relationship between the deletion of GSTM1, GSTT1 genes and susceptibility to malignant of nail matrix naevus

    Institute of Scientific and Technical Information of China (English)

    谢锋; 张正文; 李振鲁; 侴海燕; 李磊; 李昊

    2010-01-01

    目的 探讨谷胱苷肽S转移酶M1(GSTM1)、谷胱苷肽S转移酶T1(GSTT1)基因缺失与甲母痣恶变之间的关系.方法 采用聚合酶链反应(PCR)技术检测77例甲母痣恶变患者和107例甲母痣患者中GSTM1、GSTT1基因缺失的频率.结果 病例组GSTM1基因缺失的频率为58.4%,显著高于对照组的缺失频率42.1%(x2=4.811,P<0.05),危险度分析得出OR=1.938,95%CI为1.070~3.509;病例组GSTT1基因缺失的频率为57.1%,接近对照组50.5%的水平(x2=0.802,P>0.05).联合分析表明两基因在甲母痣恶变发生中具有协同作用.结论 GSTM1基因缺失或GSTM1、GSTT1基因联合缺失在甲母痣恶变患者中发生频率增高,能增加甲母痣恶变的易感性.%Objective To study the relationship between the deletion of glutathione S transferase M1 ( GSTM1), glutathione S transferase T1 ( GSTT1 ) and susceptibility to Malignant of nail matrix naevus and its mechanism. Methods Using the method of PCR to detect the genotypes of GSTM1 and GSTT1 in 77 Malignant of nail matrix naevus patients and 107 nail matrix naevns people. Results There were 58.4% (45/77) malignant patients with GSTM1 null genotype in all cases and 42. 1% (45/107) persons with GSTM1 null genotype in the nail matrix naevus people, and there was significant difference between the two groups (x2 = 4. 811, P < 0. 05 ), and its OR was 1. 938 (95% CI 1. 095-3. 581 ); There were 57. 1% (44/77) malignant patients with GSTT1 null genotype in all cases and 50. 5% (54/107) persons with GSTT1 null genotype in the nail matrix naevus people, and there wasnt significant difference between the two groups (x2 = 0. 802, P > 0. 05 ) ;There were 26 cases with GSTM1 null/GSTT1 null genotype in malignant patients which was significantly higher than those in the nail matrix naevus people, and its OR was2.451 (95%CI 1.067-5.633). Conclusion GSTM1 null genotype and GSTM1/GSTT1 combined null genotype laid in much more malignant of nail matrix naevus patients

  2. Association Study of Glutathione S-transferases Gene Polymorphisms (GSTM1 and GSTT1 with Ulcerative Colitis and Crohn's Disease in the South of Iran

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    Maryam Moini

    2017-01-01

    Full Text Available Background: Inflammatory bowel diseases (IBDs, including ulcerative colitis (UC and Crohn's disease (CD, are chronic inflammatory disorders of the gastrointestinal tract. A combination of environmental factors and interactions with a genetic predisposition are suggested to play an important role in the etiology and pathogenesis of the IBD. Glutathione S-transferases (GSTs are multifunctional enzymes involved in the cellular oxidative stress handling. Possible associations between GSTs gene polymorphisms and susceptibility to UC and CD have been reported in different population. The relationship between GSTM1 and GSTT1 deletion polymorphisms and susceptibility to UC and CD were investigated in the Iranian population. Materials and Methods: The study was performed in 106 IBD patients and 243 age- and sex-matched healthy Iranian controls consulting the IBD registry center of the Motahari Clinic, Shiraz University of Medical Sciences, Shiraz, Iran, between 2011 and 2013. GSTM1 and GSTT1 genotyping were performed using multiplex polymerase chain reaction and differences in the distribution of gene polymorphisms were analyzed statistically between the studied groups. Results: Statistically significant higher frequency of GSTM1 null genotype was observed in IBD patients (P = 0.01 and in the subgroup of patients with UC (P = 0.04 compared to healthy controls, whereas this was not true for CD patients. No significant association was found between GSTT1 gene polymorphism and UC or CD. Conclusions: Absence of GSTT1 functional gene does not play an important role in the pathophysiology and development of IBD, UC, and CD in Iranian population whereas GSTM1 null genotype could be considered as a possible genetic predisposing factor for more susceptibility to IBD and UC.

  3. Null structure groups in eleven dimensions

    CERN Document Server

    Cariglia, M; Conamhna, Oisin A. P. Mac

    2004-01-01

    We classify all the structure groups which arise as subgroups of the isotropy group, $(Spin(7)\\ltimes\\mathbb{R}^8)\\times\\mathbb{R}$, of a single null Killing spinor in eleven dimensions. We construct the spaces of spinors fixed by these groups. We determine the conditions under which structure subgroups of the maximal null strucuture group $(Spin(7)\\ltimes\\mathbb{R}^8)\\times\\mathbb{R}$ may also be embedded in SU(5), and hence the conditions under which supersymmetric spacetime admits only null, or both timelike and null, Killing spinors. This concludes, for spacetimes admitting at least one null Killing spinor, the first, purely algebraic, phase of the refined G-structure classification of supersymmetric spacetimes in eleven dimensions, the objective of which is the derivation of the general local bosonic solution of the Killing spinor equation of eleven dimensional supergravity. Finally, we discuss how the second phase of the classification, involving the direct analysis of the Killing spinor equation, may b...

  4. Interaction models of CYP1A1, GSTM1 polymorphisms and tobacco smoking in intestinal gastric cancer

    Institute of Scientific and Technical Information of China (English)

    Jing Shen; Run-Tian Wang; Yao-Chu Xu; Li-Wei Wang; Xin-Ru Wang

    2005-01-01

    AIM: To explore the interaction models of the cytochrome P-450 (CYP) 1A1 Valv ariant and glutathione S-transferase (GST)M1 null polymorphisms with tobacco smoking in the occurrence of intestinal gastric cancer.METHODS: A community-based case-control study was conducted in Yangzhong. Subjects included 114 intestinal types of gastric cancer with endoscopic and pathological diagnosis during January 1997 and December 1998, and 693 controls selected from their spouse, siblings or siblingsin-law who had no history of digestive system cancer.Logistic regression was used to estimate the interaction models.RESULTS: The frequency of the CYP1A1 Val variant allele in cases did not differ from that in controls. The OR of GSTM1 null genotype was 2.0 (95% confidence interval [95%CI]: 1.2-3.1, P<0.01). It showed a significant type 2 form of interaction model when both CYP1A1 Val variant allele and former tobacco smoking existed (i.e., among the multiplicative effects, the disease risk is increased by the tobacco exposure alone but not by the CYP1A1 variant alone). The interaction index γ was 2.8, and OReg (95%CI)was 5.0 (1.9-13.4). GSTM1 null genotype and former tobacco smoking were significant in a type 4 interaction model (i.e.,the disease risk is increased by GSTM1 null genotype or tobacco exposure alone among the multiplicative effects).The interaction index γ and OReg (95%CI) were 3.4 and 8.4 (3.4-20.9), respectively.CONCLUSION: Different interaction models of CYP1A1 Val variant allele and GSTM1 null genotype with tobacco smoking will contribute to understanding carcinogenic mechanism, but there is a need to further investigate in larger scale studies.

  5. Association of genetic polymorphism of glutathione S-transferase (GSTM1, GSTT1, GSTP1) with bladder cancer susceptibility.

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    Safarinejad, Mohammad Reza; Safarinejad, Saba; Shafiei, Nayyer; Safarinejad, Shiva

    2013-10-01

    The glutathione-S-transferases (GSTs) comprise a class of enzymes that detoxify carcinogenic compounds by conjugating glutathione to facilitate their removal. Polymorphisms in GSTM1, GSTT1, and GSTP1 genes have been related to risk for bladder cancer. Studies focusing on GSTs gene variants relationship with the risk of bladder cancer have produced conflicting and inconsistent results. We examine the association between genetic polymorphism of glutathione S-transferase P1, GSTM1, GSTT1 genes and development of bladder transitional cell carcinoma (TCC). The study population consisted of 166 histologically confirmed male bladder TCC cases and 332 healthy male controls. Genotyping was done using the polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) method and also investigated combined gene interactions. The GSTP1 Val/Val genotype was significantly associated with bladder cancer (OR = 4.32, 95% CI: 2.64-6.34), whereas the association observed for GSTM1 null (OR = 1.32, 95% CI: 0.82-2.62; P = 0.67) and GSTT1 null genotype (OR = 1.18, 95% CI: 0.79-1.67; P = 0.74) did not reach statistical significance. There was a significant multiple interaction between GSTM1, GSTT1, and GSTP1 genotypes in risk of bladder cancer (P for interaction = 0.02). The risk associated with the concurrent presence of GSTM1 positive and GSTP1 Ile/Val or Val/Val (OR = 3.71, 95% CI: 2.34-5.54) and GSTT1 positive and GSTP1 Ile/Val or Val/Val (OR = 2.66, 95% CI: 1.54-4.72) was statistically significant. Patients carrying GSTP1 Val/Val genotype were at increased risk for developing high-grade (OR = 7.68, 95% CI: 4.73-19.25) and muscle invasive (OR = 10.67, 95% CI: 6.34-21.75) bladder cancer. High risk for bladder TCC also was observed with respect to combined GSTT1 null/GSTP1 Ile/Val or Val/Val (OR = 4.76, 95% CI: 2.68-18.72) and GSTM1 null/GSTT1 null/GSTP1 Ile/Val or Val/Val (OR = 6.42, 95% CI: 4.76-14.72) genotype variant. This study suggests that the GSTP1 polymorphism

  6. Genetic polymorphisms of GSTM1, GSTP1 and GSTT1 genes and lung cancer susceptibility in the Bangladeshi population

    Institute of Scientific and Technical Information of China (English)

    Mir Muhammad Nasir Uddin; Maizbha Uddin Ahmed; Mohammad Safiqul Islam; Mohammad Siddiqul Islam; Muhammad Shahdaat Bin Sayeed; Yearul Kabir; Abul Hasnat

    2014-01-01

    To verify possible associations between polymorphisms of glutathione S-transferase Mu (GSTM1), glutathione S-transferase θ (GSTT1) and glutathione S-transferase Pi (GSTP1) genes and susceptibility to lung cancer. Methods: A total of 106 lung cancer patients and 116 controls were enrolled in a case-control study. The GSTM1 and GSTT1 were analyzed using PCR while GSTP1 was analyzed using PCR-restriction fragment length polymorphism. Risk of lung cancer was estimated as odds ratio at 95% confidence interval using unconditional logistic regression models adjusting for age, sex, and tobacco use. Results: GSTM1 null and GSTT1 null genotypes did not show a significant risk for developing lung cancer. A significantly elevated lung cancer risk was associated with GSTP1 heterozygous, mutant and combined heterozygous+mutant variants of rs1695. When classified by tobacco consumption status, no association with risk of lung cancer was found in case of tobacco smokers and nonsmokers carrying null and present genotypes of GSTM1 and GSTT1. There is a three-fold (approximately) increase in the risk of lung cancer in case of both heterozygous (AG) and heterozygous+mutant homozygous (AG+GG) genotypes whereas there is an eight-fold increase in risk of lung cancer in cases of GG with respect to AA genotype in smokers. Conclusions: Carrying the GSTM1 and GSTT1 null genotype is not a risk factor for lung cancer and GSTP1Ile105Val is associated with elevated risk of lung cancer.

  7. Genetic polymorphisms of GSTM1,GSTP1 and GSTT1 genes and lung cancer susceptibility in the Bangladeshi population

    Institute of Scientific and Technical Information of China (English)

    Mir; Muhammad; Nasir; Uddin; Maizbha; Uddin; Ahmed; Mohammad; Safiqul; Islam; Mohammad; Siddiqul; Islam; Muhammad; Shahdaat; Bin; Sayeed; Yearul; Kabir; Abul; Hasnat

    2014-01-01

    Objective:To verify possible associations between polymorphisms of glutathione S-transferase Mu(GSTM1),glutathione S-transferase θ(GSTT1) and glutathione S-transferase Pi(GSTP1)genes and susceptibility to lung cancer.Methods:A total of 106 lung cancer patients and 116 controls were enrolled in a case-control study.The GSTM1 and GSTT1 were analyzed using PCR while GSTP1 was analyzed using PCR-restriction fragment length polymorphism.Risk of lung cancer was estimated as odds ratio at 95%confidence interval using unconditional logistic regression models adjusting for age,sex,and tobacco use.Results:GSTM1 null and GSTT1 null genotypes did not show a significant risk for developing lung cancer.A significandy elevated lung cancer risk was associated with GSTP1 heterozygous,mutant and combined heterozygous+mutant variants of rs1695.When classified by tobacco consumption status,no association with risk of lung cancer was found in case of tobacco smokers and nonsmokers carrying null and present genotypes of GSTM1 and GSTTL There is a three-fold(approximately) increase in the risk of lung cancer in case of both heterozygous(AG) and heterozygous+mutant homozygous(AG+GG) genotypes whereas there is an eightfold increase in risk of lung cancer in cases of GG with respect to AA genotype in smokers.Conclusions:Carrying the GSTM1 and GSTT1 null genotype is not a risk factor for lung cancer and GSTP1Ile105 Val is associated with elevated risk of lung cancer.

  8. GSTP1, GSTM1, and GSTT1 genetic polymorphisms in patients with cryptogenic liver cirrhosis.

    Science.gov (United States)

    Ghobadloo, Shahrokh Mohammadzadeh; Yaghmaei, Bahram; Bakayev, Valery; Goudarzi, Hossein; Noorinayer, Babak; Rad, Farhad Haghighi; Samiy, Saeed; Aghabozorghi, Sohrab; Zali, Mohammad Reza

    2004-01-01

    We investigated glutathione S-transferase (GST) P1 Ile (105) Val, T1, and M1 polymorphisms in 45 patients with documented cryptogenic cirrhosis and 56 healthy control subjects. Polymerase chain reaction-based procedures were performed in the studied populations to confirm the genotypes of GSTT1, M1, and P1. Ile/Val and Val/Val GSTP1 genotypes were more frequent in the patients with cirrhosis (n=39, 87%) than in the control subjects (n=10; 18%) (odds ratio [OR] 34.04; 95% confidence interval [CI] 10.70 to 108.31, Pcirrhosis, 16 were heterozygous and 23 were homozygous, whereas only one person in the control group was homozygous. The GSTM1 null genotype was also more prevalent in cirrhotic patients than in healthy control subjects (OR 6.83, 95% CI 2.53 to 18.42, Pcirrhosis by unknown mechanisms. The significant association of cryptogenic cirrhosis with Val/Val GSTP1 genotype encoding a low detoxification activity protein implicates this polymorphism as a risk factor for the occurrence of the disease.

  9. Association between GSTM1 and GSTT1 polymorphisms and esophageal squamous cell carcinoma: results from a case-control study in Kashmir, India.

    Science.gov (United States)

    Makhdoomi, Muzamil Ashraf; Shah, Idrees Ayoub; Bhat, Gulzar Ahmad; Amin, Shajrul; Lone, Mohd Maqbool; Islami, Farhad; Dar, Nazir Ahmad

    2015-04-01

    Polymorphisms in glutathione-S-transferases (GSTs), the phase II xenobiotic detoxifying enzymes, have been associated with increased cancer risk. In this study, we assessed the association of functional polymorphisms in GSTM1 and GSTT1 with esophageal cancer in Kashmir, India, an area with a high incidence of esophageal squamous cell carcinoma (ESCC). We analyzed genotypes of GSTM1 and GSTT1 using a multiplex PCR in 492 pairs of ESCC cases and individually matched controls. The associations between polymorphisms in these genes and ESCC risk were examined by conditional logistic regression models adjusted for multiple potential confounders. In addition, the interaction between these genes and several environmental exposures with regard to ESCC risk was assessed. Our results showed an association between the GSTT1 null genotype and ESCC risk (odds ratio (OR) = 1.58; 95% confidence interval (CI) 1.04-2.39). Although GSTM1 alone was not associated with ESCC risk, individuals with the GSTM1 (-)/GSTT1 (+) genotype showed an inverse relation with ESCC risk (OR = 0.55; 95% CI 0.32-0.93), compared to GSTM1 (+)/GSTT1 (+) individuals. We found a significant interaction between the GSTT1 and GSTM1 genotypes with regard to ESCC risk (P = 0.001); however, there were no interactions between environmental factors and GSTT1 and GSTM1 genotypes. This study indicates that GSTT1 null genotype is associated with ESCC risk in Kashmiri population. The association between GSTM1 and ESCC risk needs further investigations. Interactions of these genotypes with environmental exposures should be examined in multicentric studies with bigger sample sizes.

  10. Análise dos genes GSTM1 e GSTT1 em pacientes com câncer de cabeça e pescoço GSTM1 and GSTT1 genes analysis in head and neck cancer patients

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    Cássia Veridiana Dourado Leme

    2010-01-01

    multiplex polymerase chain reaction. For statistical analysis, data were tabulated and compared by the Fisher’s exact test, the Chi-square test and multiple logistic regression were also used. RESULTS: There was prevalence of smokers (OR = 5.32, CI 95% CI = 2.04-13.86 p = 0.0006, alcohol drinkers (OR = 5.04, CI 95% = 2.19-11.59 p = 0.0001 in head and neck cancer patients . The GSTT1 null genotype was found in 47% of the patient and 41% of the control group (OR = 0.67; CI 95%= 0.34-1.35; p = 0.2648. Likewise , the GSTM1 null genotype was found in 66% of the patient and 75% of the control group (OR = 2.25; CI 95%= 1.05 - 4.84; p = 0.0368. The combined GSTT1 and GSTM1 gene null genotype shown association between GSTM1*0/GSTT1 and occurrence of head and neck carcinoma (OR = 7.64; CI 95%= 1.72-34.04; p = 0.0076. Analysis of clinical-pathological features showed association between GSTT1 null genotype and larynx, the inverse relation between this genotype and pharynx. CONCLUSION: In our study it was possible to establish association between GSTM1 null genotypes and head and neck cancer.

  11. Combined effect of prenatal solvent exposure and GSTT1 or GSTM1 polymorphisms in the risk of birth defects.

    Science.gov (United States)

    Garlantézec, Ronan; Chevrier, Cécile; Coiffec, Isabelle; Celebi, Catherine; Cordier, Sylvaine

    2012-06-01

    Exposure to solvents during pregnancy has long been suspected to increase the risk of congenital malformations. Glutathione S-transferases (GSTs) are enzymes essential for the detoxification of various chemicals. Our objective here was to assess whether GST polymorphisms might modify the association between maternal solvent exposure and the risk of birth defects. A prospective cohort included 3421 pregnant women in Brittany, France (2002-2006). Occupational exposure to solvents was assessed from a job-exposure matrix. Congenital malformations were diagnosed among livebirths, stillbirths, and medical pregnancy terminations. Using a nested case-control design, 32 babies with major birth defects were compared to 348 normal births for babies' cord blood genotypes (at GSTT1 and GSTM1) and maternal occupational solvent exposure. Logistic models were used to adjust for potential confounders. The risk of major defects increased significantly in women with solvent exposure (20% of controls and 34% of cases). Frequencies of the null genotype of both the GSTT1 and GSTM1 genes were similar among controls and cases. There was a significantly increased risk of birth defects in GSTM1 not-null cord-blood genotype in pregnancies exposed to solvents (odds ratio [OR], 1.0 for not-null, not-exposed; OR, 4.0 for not-null, exposed; 95% confidence interval [CI], 1.4-11.2; OR, 1.6 for null, not-exposed; 95% CI, 0.6-3.9; OR, 1.0 for null, exposed; 95% CI, 0.2-4.7; p = 0.05). This nested case-control study suggests that the child's GSTM1 genotype modifies the risk of major birth defects among offspring of solvent-exposed women. Replication and additional investigations are necessary to confirm and elucidate these findings.

  12. Cruciferous vegetable supplementation in a controlled diet study alters the serum peptidome in a GSTM1-genotype dependent manner

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    Chen Chu

    2011-01-01

    Full Text Available Abstract Background Cruciferous vegetable intake is inversely associated with the risk of several cancers. Isothiocyanates (ITC are hypothesized to be the major bioactive constituents contributing to these cancer-preventive effects. The polymorphic glutathione-S-transferase (GST gene family encodes several enzymes which catalyze ITC degradation in vivo. Methods We utilized high throughput proteomics methods to examine how human serum peptides (the "peptidome" change in response to cruciferous vegetable feeding in individuals of different GSTM1 genotypes. In two randomized, crossover, controlled feeding studies (EAT and 2EAT participants consumed a fruit- and vegetable-free basal diet and the basal diet supplemented with cruciferous vegetables. Serum samples collected at the end of the feeding period were fractionated and matrix assisted laser desorption/ionization-time of flight (MALDI-TOF mass spectrometry spectra were obtained. Peak identification/alignment computer algorithms and mixed effects models were used to analyze the data. Results After analysis of spectra from EAT participants, 24 distinct peaks showed statistically significant differences associated with cruciferous vegetable intake. Twenty of these peaks were driven by their GSTM1 genotype (i.e., GSTM1+ or GSTM1- null. When data from EAT and 2EAT participants were compared by joint processing of spectra to align a common set, 6 peaks showed consistent changes in both studies in a genotype-dependent manner. The peaks at 6700 m/z and 9565 m/z were identified as an isoform of transthyretin (TTR and a fragment of zinc α2-glycoprotein (ZAG, respectively. Conclusions Cruciferous vegetable intake in GSTM1+ individuals led to changes in circulating levels of several peptides/proteins, including TTR and a fragment of ZAG. TTR is a known marker of nutritional status and ZAG is an adipokine that plays a role in lipid mobilization. The results of this study present evidence that the GSTM1

  13. GSTM1 and APE1 genotypes affect arsenic-induced oxidative stress: a repeated measures study

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    Quamruzzaman Quazi

    2007-12-01

    Full Text Available Abstract Background Chronic arsenic exposure is associated with an increased risk of skin, bladder and lung cancers. Generation of oxidative stress may contribute to arsenic carcinogenesis. Methods To investigate the association between arsenic exposure and oxidative stress, urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG was evaluated in a cohort of 97 women recruited from an arsenic-endemic region of Bangladesh in 2003. Arsenic exposure was measured in urine, toenails, and drinking water. Drinking water and urine samples were collected on three consecutive days. Susceptibility to oxidative stress was evaluated by genotyping relevant polymorphisms in glutathione-s transferase mu (GSTM1, human 8-oxoguanine glycosylase (hOGG1 and apurinic/apyrimidinic endonuclease (APE1 genes using the Taqman method. Data were analyzed using random effects Tobit regression to account for repeated measures and 8-OHdG values below the detection limit. Results A consistent negative effect for APE1 was observed across water, toenail and urinary arsenic models. APE1 148 glu/glu + asp/glu genotype was associated with a decrease in logged 8-OHdG of 0.40 (95%CI -0.73, -0.07 compared to APE1 148 asp/asp. An association between total urinary arsenic and 8-OHdG was observed among women with the GSTM1 null genotype but not in women with GSTM1 positive. Among women with GSTM1 null, a comparison of the second, third, and fourth quartiles of total urinary arsenic to the first quartile resulted in a 0.84 increase (95% CI 0.27, 1.42, a 0.98 increase (95% CI 033, 1.66 and a 0.85 increase (95% CI 0.27, 1.44 in logged 8-OHdG, respectively. No effects between 8-OHdG and toenail arsenic or drinking water arsenic were observed. Conclusion These results suggest the APE1 variant genotype decreases repair of 8-OHdG and that arsenic exposure is associated with oxidative stress in women who lack a functional GSTM1 detoxification enzyme.

  14. Genetic polymorphisms of GSTM1, GSTT1, and GSTP1 with prostate cancer risk: a meta-analysis of 57 studies.

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    Mancheng Gong

    Full Text Available BACKGROUND AND OBJECTIVES: The GSTM1, GSTT1 and GSTP1 polymorphisms might be involved in inactivation of procarcinogens that contribute to the genesis and progression of cancers. However, studies investigating the association between GSTM1, GSTT1 or GSTP1 polymorphisms and prostate cancer (PCa risk report conflicting results, therefore, we conducted a meta-analysis to re-examine the controversy. METHODS: Published literature from PubMed, Embase, Google Scholar and China National Knowledge Infrastructure (CNKI were searched (updated to June 2, 2012. According to our inclusion criteria, studies that observed the association between GSTM1, GSTT1 or GSTP1 polymorphisms and PCa risk were included. The principal outcome measure was the odds ratio (OR with 95% confidence interval (CI for the risk of PCa associated with GSTM1, GSTT1 and GSTP1 polymorphisms. RESULTS: Fifty-seven studies involving 11313 cases and 12934 controls were recruited. The overall OR, which was 1.2854 (95% CI = 1.1405-1.4487, revealed a significant risk of PCa and GSTM1 null genotype, and the similar results were observed when stratified by ethnicity and control source. Further, the more important is that the present study first reported the high risks of PCa for people who with dual null genotype of GSTM1 and GSTT1 (OR = 1.4353, 95% CI = 1.0345-1.9913, or who with GSTT1 null genotype and GSTP1 A131G polymorphism (OR = 1.7335, 95% CI = 1.1067-2.7152. But no association was determined between GSTT1 null genotype (OR = 1.102, 95% CI = 0.9596-1.2655 or GSTP1 A131G polymorphism (OR = 1.0845, 95% CI = 0.96-1.2251 and the PCa risk. CONCLUSIONS: Our meta-analysis suggested that the people with GSTM1 null genotype, with dual null genotype of GSTM1 and GSTT1, or with GSTT1 null genotype and GSTP1 A131G polymorphism are associated with high risks of PCa, but no association was found between GSTT1 null genotype or GSTP1 A131G polymorphism and the risk of

  15. GSTT1 and GSTM1 polymorphisms and myelodysplastic syndrome risk: a systematic review and meta-analysis.

    Science.gov (United States)

    Dahabreh, Issa J; Giannouli, Stavroula; Gota, Vaia; Voulgarelis, Michael

    2010-04-01

    Glutathione-S-transferace polymorphisms may make hematopoietic lineage cells susceptible to genotoxicity following exposure to heavy metals or benzene. We conducted a systematic review and meta-analysis to define the effect of GSTM1 and GSTT1 null polymorphisms on MDS risk. We searched the PubMed and SCOPUS databases to identify peer-reviewed published case-control studies investigating the association between GSTT1 and/or GSTM1 null genotypes and development of MDS. Between-study heterogeneity was assessed using Cochran's Q statistic and the I(2) statistic. Odds ratios from individual studies were pooled using fixed and random effects models. Thirteen studies were considered eligible for the GSTT1 meta-analysis (1471 cases, 1907 controls) and 10 were considered eligible for the GSTM1 meta-analysis (1161 cases, 1668 controls). For the GSTT1 polymorphism, there was moderate between study heterogeneity (p(Q) = 0.01; I(2) = 52.3%) and the null genotype was significantly associated with increased risk of MDS development, random effects OR = 1.43 (95% CI, 1.09-1.89); p = 0.01. For the GSTM1 polymorphisms there was moderate between-study heterogeneity (p = 0.07; I(2) = 43.1%) and the random effects OR = 1.02 (95% CI, 0.82-1.28) was non-significant (p = 0.85). The GSTT1 null genotype is a significant risk factor for MDS development. Gene-environment interactions need to be further explored.

  16. [CYP1A1 polymorphisms, lack of glutathione S-transferase M1 (GSTM1), cooking oil fumes and lung cancer risk in non-smoking women].

    Science.gov (United States)

    Zhu, Xiao-Xia; Hu, Cheng-Ping; Gu, Qi-Hua

    2010-11-01

    to study the correlation of polymorphisms of CYP1A1 MspI, GSTM1 null genotype, cooking oil fumes independently and in combination with the risk of non-smoking lung cancer in females. one hundred and sixty female non-smoking patients with primary lung cancer and 160 controls were enrolled from Xiangya Hospital of Central South University. PCR-RELP and PCR were used to detect the distribution of CYP1A1 MspI and GSTM1 genotypes respectively. The correlation of these genes and cooking oil fumes with the susceptibility to lung cancer was analyzed. There was a significant difference in the frequencies of cooking oil fumes exposure between cancer cases and controls (χ(2) = 10.734, P 0.05). The combination of CYP1A1 polymorphisms and cooking oil fumes significantly increased the risk of lung cancer. The frequencies of GSTM1 null genotype was significantly different between cancer cases and controls (χ(2) = 0.518, P cooking fumes had a higher risk of cancer than those with only one of them, the OR being 3.617 (95%CI 1.899 - 6.891). The combination of the two genes significantly increased the risk of lung cancer. cooking oil fumes exposure was a risk factor for non-smoking lung cancer in females. The combination of CYP1A1 with cooking oil fume increased the risk of female lung cancer. GSTM1 null genotype was associated with risk of lung cancer in non-smoking females. The combination of GSTM1 null genotype and cooking oil fumes significantly increased the risk of female lung cancer. The combination of CYP1A1 and GSTM1 significantly increased the risk of lung cancer.

  17. Relationship of GSTM1 and GSTT1 genetic variant and markers of oxidative stress and inflammation in smokers with coronary artery disease

    Institute of Scientific and Technical Information of China (English)

    ChanggaoZhou; Jianjin Tang; Mingwei Wang; Jianjun Yan; Qiming Wang; Jun Zhu; Zhijian Yang; Liansheng Wang

    2009-01-01

    Objective: To investigate the role of glutathione S-transferase (GST) genetic variants and markcrs of oxidative stress and inflammation in smoking-related coronary artery disease (CAD) patients. Methods: Five hundred and thirty-five Chinese CAD patients were successfully gcnotyped. Plasma total antioxidant status (TAOS), glutathione, C-reactive protein (CRP), fibfinogen(FIB) and white blood cell count (WBC) were determined to evaluate the oxidative stress and inflammatory response. Results: GSTM1-0/ GSTT1-0 subjects had a higher CRP, FIB, WBC and GSH and a lower TAOS compared to patients with wild-type GSTM1/GSTT1 genes, but there was significant difference only with regards to TAOS. Smokers with the null genotype of GSTT1 had the highest CRP and the lowest TAOS and GSH when compared to the GSTT1-1 genotype with smoking status, or the GSTT1-0 genotype with non-smoking stares, or the GSTT1-1 genotypc with non-smoking status. However, we found no significant difference between these groups. Also, no significant interaction was observed between genotypes and smoking stares in determining CRP levels. Conclusion: Our results suggest that GST polymorphisms do not modify the effect of smoking on markers of oxidative stress and inflammation in Chinese CAD patients.

  18. GSTM1, GSTT1, and NQO1 polymorphisms in cervical carcinogenesis.

    Science.gov (United States)

    Nunobiki, Osamu; Ueda, Masatsugu; Akise, Hikari; Izuma, Shinji; Torii, Kiyo; Okamoto, Yoshiaki; Tanaka, Ichiro; Noda, Sadamu; Akashi, Kyoko; Higashida, Taro

    2015-07-01

    The aim of the study is to investigate the clinical significance of glutathione-S-transferase GSTM1, GSTT1, and NQO1 c.609C>T (rs1800566) genetic polymorphisms in cervical carcinogenesis. GSTM1, GSTT1, and NQO1 polymorphisms together with human papillomavirus (HPV) types were examined in a total of 192 cervical smear in exfoliated cervical cell samples using polymerase chain reaction (PCR) system and real-time polymerase chain reaction (PCR) system. The 19 patients with high-grade squamous intraepithelial lesion had statistically higher frequency of null GSTT1 genotype than 9 with low-grade squamous intraepithelial lesion (LSIL) among the 67 patients with high-risk HPV (P = 0.024). The 24 patients with HSIL had also statistically higher frequency of NQO1 (CT+TT) genotype than 14 with LSIL among the 67 patients with high-risk HPV (P = 0.024). GSTT1 null and NQO1 genotype in cervical cell samples may be associated with more severe precancerous lesions of the cervix in a Japanese population.

  19. Interactions among GSTM1, GSTT1 and GSTP1 polymorphisms, cruciferous vegetable intake and breast cancer risk.

    Science.gov (United States)

    Steck, S E; Gaudet, M M; Britton, J A; Teitelbaum, S L; Terry, M B; Neugut, A I; Santella, R M; Gammon, M D

    2007-09-01

    Isothiocyanates are anticarcinogenic phytochemicals found in cruciferous vegetables that both induce and are substrates for the gluthatione S-transferases (GSTs). The GSTs are phase II metabolizing enzymes involved in metabolism of various bioactive compounds. Functional polymorphisms in GST genes have been identified and may interact with cruciferous vegetable intake to affect cancer risk. We examined this hypothesis using data from the Long Island Breast Cancer Study Project, a population-based case-control study conducted in Long Island, NY, from 1996 to 1997. Cruciferous vegetable intake in the previous year was assessed via modified Block food frequency questionnaire. DNA was extracted from blood samples (n = 1052 cases and n = 1098 controls) and genotyped for GSTM1 deletion, GSTT1 deletion and GSTP1 Ile105Val using multiplex polymerase chain reaction and Taqman assays. Unconditional logistic regression was used to estimate adjusted odds ratios (ORs) and 95% confidence intervals (CI). We found an 86% increase in the OR for breast cancer among carriers of the GSTM1 null, GSTT1 null and GSTP 105Ile/Ile genotypes (OR = 1.86, 95% CI = 1.12, 3.08) and a 36% decrease in the OR among carriers of GSTM1 present, GSTT1 null and GSTP1 105Ile/Val + Val/Val genotypes (OR = 0.64, 95% CI = 0.42, 0.97) compared with GSTM1 present, GSTT1 present and GSTP1 105Ile/Ile carriers. We found no joint effects among GST polymorphisms and cruciferous vegetable intake and breast cancer risk. In conclusion, we found associations between specific combinations of three GST gene polymorphisms and breast cancer risk but these did not modify the association between cruciferous vegetable intake and breast cancer. Additional studies are needed to confirm the associations observed.

  20. Genetic polymorphisms of glutathione S-transferase genes GSTM1, GSTT1 and risk of hepatocellular carcinoma.

    Directory of Open Access Journals (Sweden)

    Kang Song

    Full Text Available BACKGROUND: A number of case-control studies were conducted to investigate the association of glutathione S-transferase (GST genetic polymorphisms and hepatocellular carcinoma (HCC risk. However, these studies have yielded contradictory results. We therefore performed a meta-analysis to derive a more precise estimation of the association between polymorphisms on GSTM1, GSTT1 and HCC. METHODOLOGY/PRINICPAL FINDINGS: PubMed, EMBASE, ISI web of science and the CNKI databases were systematically searched to identify relevant studies. Data were abstracted independently by two reviewers. Odds ratios (ORs and 95% confidence intervals (95% CIs were used to assess the strength of association. Potential sources of heterogeneity were also assessed by subgroup analysis and meta-regression. Funnel plots and Egger's linear regression were used to test publication bias among the articles. A total of 34 studies including 4,463 cases and 6,857 controls were included in this meta-analysis. In a combined analysis, significantly increased HCC risks were found for null genotype of GSTM1 (OR = 1.29, 95% CI: 1.06-1.58; P = 0.01 and GSTT1 (OR = 1.43, 95% CI: 1.22-1.68; P<10(-5. Potential sources of heterogeneity were explored by subgroup analysis and meta-regression. Significant results were found in East Asians and Indians when stratified by ethnicity; whereas no significant associations were found among Caucasians and African populations. By pooling data from 12 studies that considered combinations of GSTT1 and GSTM1 null genotypes, a statistically significant increased risk for HCC (OR = 1.88, 95% CI: 1.41-2.50; P<10(-4 was detected for individuals with combined deletion mutations in both genes compared with positive genotypes. CONCLUSIONS/SIGNIFICANCE: This meta-analysis suggests that the GSTM1 and GSTT1 null genotype may slightly increase the risk of HCC and that interaction between unfavourable GSTs genotypes may exist.

  1. GSTM1 genotype influences the susceptibility of men to sperm DNA damage associated with exposure to air pollution.

    Science.gov (United States)

    Rubes, Jiri; Selevan, Sherry G; Sram, Radim J; Evenson, Donald P; Perreault, Sally D

    2007-12-01

    Previous studies have provided evidence for an association between exposure to high levels of air pollution and increased DNA damage in human sperm. In these studies DNA damage was measured using the sperm chromatin structure assay (SCSA) wherein the percentage of sperm with abnormal chromatin/fragmented DNA is determined and expressed as % DNA fragmentation index (%DFI). Here we extend these observations to address the following hypothesis: men who are homozygous null for glutathione-S-transferase M1 (GSTM1-) are less able to detoxify reactive metabolites of carcinogenic polycyclic aromatic hydrocarbons (c-PAHs) found in air pollution. Consequently they are more susceptible to the effects of air pollution on sperm chromatin. Using a longitudinal study design in which men provided semen samples during periods of both low (baseline) and episodically high air pollution, this study revealed a statistically significant association between GSTM1 null genotype and increased SCSA-defined %DFI (beta=0.309; 95% CI: 0.129, 0.489). Furthermore, GSTM1 null men also showed higher %DFI in response to exposure to intermittent air pollution (beta=0.487; 95% CI: 0.243, 0.731). This study thus provides novel evidence for a gene-environment interaction between GSTM1 and air pollution (presumably c-PAHs). The significance of the findings in this study with respect to fertility status is unknown. However, it is biologically plausible that increases in %DFI induced by such exposures could impact the risk of male sub/infertility, especially in men who naturally exhibit high levels of %DFI.

  2. Polymorphisms of GSTM1 and CYP1A1 genes and their genetic susceptibility to prostate cancer in Chinese men

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Background Variation in prostate cancer incidence between different racial groups has been well documented,for which genetic polymorphisms are hypothesized to be an explanation.We evaluated the association between polymorphisms in the cytochrome P-450 CYP1A1(CYP1A1)and glutathione S-transferase M1(GSTM1)genes and genetic susceptibility to prostate cancer in Chinese men.Methods Two hundred and eight prostate cancer patients and 230 age matched controls were enrolled in this study.All DNA samples from peripheral blood lymphocytes were genotyped for common genetic polymorphisms of the CYP1A1 and GSTM1 genes using the oligonucleotide microarray(DNA chip)technique and the polymorphism results confirmed by sequencing.The different polymorphisms in prostate cancer patients were also analyzed according to age at diagnosis,prostate specific antigen level,cancer stage and grade(Gleason score).Results The prevalence of the GSTM1(0/0)genotype was significantly higher in prostate cancer patients(58.2%)than in controls(41.7%,P<0.05).Further analysis demonstrated that the prostate cancer patients with a GSTM1(0/0)genotype were younger than those with the GSTM1(+/+)genotype(P=0.024).No significant differences in the frequency distributions of CYP1A1 polymorphisms were observed between prostate cancer patients and controls.Conclusion GSTM1(0/0)gene polymorphism may be linked to prostate cancer risk and early age of onset in Chinese.

  3. Association of glutathione S-transferase (GSTM1, T1 and P1 gene polymorphisms with type 2 diabetes mellitus in north Indian population

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    Bid H

    2010-01-01

    Full Text Available Background: Diabetes mellitus is associated with an increased production of reactive oxygen species (ROS and a reduction in antioxidant defense. The oxidative stress becomes evident as a result of accumulation of ROS in conditions of inflammation and Type 2 diabetes mellitus (T2DM. The genes involved in redox balance, which determines the susceptibility to T2DM remain unclear. In humans, the glutathione S-transferase (GST family comprises several classes of GST isozymes, the polymorphic variants of GSTM1, T1 and P1 genes result in decreased or loss of enzyme activity. Aims: The present study evaluated the effect of genetic polymorphisms of the GST gene family on the risk of developing T2DM in the North Indian population. Settings and Design: GSTM1, T1 and P1 polymorphisms were genotyped in 100 T2DM patients and 200 healthy controls from North India to analyze their association with T2DM susceptibility. Materials and Methods: Analysis of GSTM1 and GSTT1 gene polymorphisms was performed by multiplex polymerase chain reaction (PCR and GSTP1 by PCR-Restriction Fragment Length Polymorphism (RFLP. Statistical Analysis: Fisher′s exact test and χ2 statistics using SPSS software (Version-15.0. Results: We observed significant association of GSTM1 null (P=0.004, OR= 2.042, 95%CI= 1.254-3.325 and GSTP1 (I/V (P=0.001, OR= 0.397, 95%CI=0.225-0.701 with T2DM and no significant association with GSTT1 (P=0.493. The combined analysis of the three genotypes GSTM1 null, T1 present and P1 (I/I demonstrated an increase in T2DM risk (P= 0.005, OR= 2.431 95% CI=1.315-4.496. Conclusions: This is the first study showing the association of a combined effect of GSTM1, T1 and P1 genotypes in a representative cohort of Indian patients with T2DM. Since significant association was seen in GSTM1 null and GSTP1 (I/V and multiple association in GSTM1 null, T1 present and P1 (I/I, these polymorphisms can be screened in the population to determine the diabetic risk.

  4. [Lymphocyte metabolism in patients with acute pancreatitis with different genotypes of GSTM1 and GSTT1 genes].

    Science.gov (United States)

    Markova, E V; Zotova, N V; Savchenko, A A; Titova, N M; Slepov, E V; Cherdantsev, D V; Konovalenko, A N

    2006-01-01

    In this study, we have investigated correlation between enzymatic activity of NAD(P)-dependent dehydrogenases of lymphocytes and polymorphic variants of glutathione S-transferase M1 (GSTM1) and T1 (GSTT1) genes in the group of unrelated patients with acute pancreatitis in comparison with healthy Russians from Krasnoyarsk. Thus, genotype GSTM1 0/0 is the marker of predisposition to the acute pancreatitis, wheras polymorphism of the GSTT1 gene is not involved in the development of the pancreatitis, at least in our group. The bioluminescence analysis showed statistically significant decrease of the levels of G3PD, NAD(+)MDH and the increase of NADH(+)LDH, NAD(+)GDH, NADH(+)GDH in lymphocytes of pancreatic group. Development of pancreatitis in patients with different genotypes GSTM1 and GSTT1 genes showed the rearrangement of the basic intracellular processes: dominance of a plastic metabolism in the patients with GSTM1--deletions and predominance of energetic processes at GSTT1 0 - pancreatitis.

  5. Influence of CYP2C9, GSTM1, GSTT1 and NAT2 genetic polymorphisms on DNA damage in workers occupationally exposed to organophosphate pesticides.

    Science.gov (United States)

    Singh, Satyender; Kumar, Vivek; Singh, Priyanka; Banerjee, Basu Dev; Rautela, Rajender Singh; Grover, Shyam Sunder; Rawat, Devendra Singh; Pasha, Syed Tazeen; Jain, Sudhir Kumar; Rai, Arvind

    2012-01-24

    Previous studies have revealed that organophosphate pesticides (OPs) are primarily metabolized by xenobiotic metabolizing enzymes (XMEs). Very few studies have explored genetic polymorphisms of XMEs and their association with DNA damage in pesticides-exposed workers. Present study was designed to determine the influence of CYP2C9, GSTM1, GSTT1 and NAT2 genetic polymorphisms on DNA damage in workers occupationally exposed to OPs. We examined 268 subjects including 134 workers occupationally exposed to OPs and an equal number of normal healthy controls. The DNA damage was evaluated using alkaline comet assay and genotyping was done using individual polymerase chain reaction (PCR) or polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Acetylcholinesterase and paraoxonase activity were found to be significantly lowered in workers as compared to control subjects which were analyzed as biomarkers of toxicity due to OPs exposure (p<0.001). Workers showed significantly higher DNA tail moment (TM) compared to control subjects (14.32±2.17 vs. 6.24±1.37 tail % DNA, p<0.001). GSTM1 null genotype was found to influence DNA TM in workers (p<0.05). DNA TM was also found to be increased with concomitant presence of NAT2 slow acetylation and CYP2C9*3/*3 or GSTM1 null genotypes (p<0.05). DNA TM was found increased in NAT2 slow acetylators with mild and heavy smoking habits in control subjects and workers, respectively (p<0.05). The results of this study suggest that GSTM1 null genotypes, and an association of NAT2 slow acetylation genotypes with CYP2C9*3/*3 or GSTM1 null genotypes may modulate DNA damage in workers occupationally exposed to OPs.

  6. Genetic polymorphisms in folate pathway enzymes, DRD4 and GSTM1 are related to temporomandibular disorder

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    Mayor-Olea Alvaro

    2011-05-01

    Dehydrogenase (MTHFD rs2236225 (OR = 3.09; 95%CI 1.27, 7.50; p = 0.016 and allele A of Methionine Synthase Reductase (MTRR rs1801394 (OR = 2.35; 95CI 1.10, 5.00; p = 0.037. An inflammatory oxidative stress enzyme, Gluthatione S-Tranferase Mu-1(GSTM1, null allele (OR = 2.21; 95%CI 1.24, 4.36; p = 0.030 and a neurotransmission receptor, Dopamine Receptor D4 (DRD4, long allele of 48 bp-repeat (OR = 3.62; 95%CI 0.76, 17.26; p = 0.161. Conclusions Some genetic polymorphisms related to folates metabolism, inflammatory oxidative stress, and neurotransmission responses to pain, has been significantly associated to TMD syndrome

  7. Modulation of human serum glutathione S-transferase A1/2 concentration by cruciferous vegetables in a controlled feeding study is influenced by GSTM1 and GSTT1 genotypes.

    Science.gov (United States)

    Navarro, Sandi L; Chang, Jyh-Lurn; Peterson, Sabrina; Chen, Chu; King, Irena B; Schwarz, Yvonne; Li, Shuying S; Li, Lin; Potter, John D; Lampe, Johanna W

    2009-11-01

    Glutathione S-transferases (GST) detoxify a wide range of carcinogens. Isothiocyanates (ITC), from cruciferous vegetables, are substrates for and inducers of GST. GST variants may alter ITC clearance such that response to crucifers varies by genotype. In a randomized cross-over trial, we tested the hypothesis that changes in serum GSTA1/2 concentration in response to cruciferous vegetable feeding depends on GSTM1/GSTT1 genotype. Thirty-three men and 34 women (age 20-40 years) ate four 14-day controlled diets--basal (vegetable-free), basal supplemented with two different doses of crucifers ("single dose" and "double dose"), and single-dose cruciferous-plus-apiaceous vegetables--fed per kilogram of body weight. Fasting bloods from days 0, 7, 11, and 14 of each diet period were analyzed for serum GSTA1/2 by ELISA. GSTA1/2 increased with single- and double-dose cruciferous compared with basal diet (10% and 13%, respectively; P = 0.02 and 0.004), but cruciferous-plus-apiaceous did not differ from basal (P = 0.59). Overall, GSTA1/2 was higher in GSTM1-null/GSTT1-null than GSTM1+/GSTT1+ individuals (4,198 +/- 338 and 3,372 +/- 183 pg/mL; P = 0.03). The formal interaction of genotype-by-diet was not statistically significant, but the GSTA1/2 increase during the single-dose cruciferous diet was among GSTM1-null/GSTT1-null individuals (by 28%; P = 0.008), largely explained by GSTM1-null/GSTT1-null men (by 41%; P = 0.01). GSTA1/2 increased during the double-dose cruciferous diet in both GSTM1-null/GSTT1-null men (by 35%; P = 0.04) and GSTM1+/GSTT1+ men (by 26%; P = 0.01) but not in women. In summary, cruciferous vegetable supplementation increased GSTA1/2, but the effect was most marked in GSTM1-null/GSTT1-null men.

  8. Polymorphisms in GSTM1, GSTT1, GSTP1, and GSTM3 genes and breast cancer risk in northeastern Mexico.

    Science.gov (United States)

    Jaramillo-Rangel, G; Ortega-Martínez, M; Cerda-Flores, R M; Barrera-Saldaña, H A

    2015-06-11

    Glutathione S-transferases (GSTs) are a family of phase II metabolizing enzymes involved in carcinogen detoxification and the metabolism of various bioactive compounds. Several genes that code for these enzymes are polymorphic in an ethnicity-dependent manner, with particular genotypes previously associated with an increased risk of breast cancer. The purpose of this study was to determine the frequencies of polymorphisms in the genes GSTM1, GSTT1, GSTP1, and GSTM3 and to investigate whether an association exists between these genes and breast cancer risk in subjects from northeastern Mexico. Genotypes were determined for 243 women with histologically confirmed breast cancer and 118 control subjects. Gene polymorphisms were analyzed using a DNA microarray. We found an increased breast cancer risk associated with the GSTM1 gene deletion polymorphism (OR = 2.19; 95%CI = 1.50-3.21; P = 0.001). No associations between the GSTT1, GSTP1, and GSTM3 genotypes and neoplasia risk were observed. In conclusion, we determined the genotype distribution of GST polymorphisms in control subjects and breast cancer patients from northeastern Mexico. The GSTM1 null genotype was associated with breast cancer risk. Our findings may be used to individualize breast cancer screening and therapeutic intervention in our population, which displays ethnic characteristics that differentiate it from other populations in Mexico.

  9. Resistance to acetaminophen-induced hepatotoxicity in glutathione S-transferase Mu 1-null mice.

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    Arakawa, Shingo; Maejima, Takanori; Fujimoto, Kazunori; Yamaguchi, Takashi; Yagi, Masae; Sugiura, Tomomi; Atsumi, Ryo; Yamazoe, Yasushi

    2012-01-01

    We investigated the role of glutathione S-transferases Mu 1 (GSTM1) in acetaminophen (APAP)-induced hepatotoxicity using Gstm1-null mice. A single oral administration of APAP resulted in a marked increase in plasma alanine aminotransferase accompanied by hepatocyte necrosis 24 hr after administration in wild-type mice, but its magnitude was unexpectedly attenuated in Gstm1-null mice. Therefore, it is suggested that Gstm1-null mice are resistant to APAP-induced hepatotoxicity. To examine the mechanism of this resistance in Gstm1-null mice, we measured phosphorylation of c-jun N-terminal kinase (JNK), which mediates the signal of APAP-induced hepatocyte necrosis, by Western blot analysis 2 and 6 hr after APAP administration. A marked increase in phosphorylated JNK was observed in wild-type mice, but the increase was markedly suppressed in Gstm1-null mice. Therefore, it is suggested that suppressed phosphorylation of JNK may be a main mechanism of the resistance to APAP-induced hepatotoxicity in Gstm1-null mice, although other possibilities of the mechanism cannot be eliminated. Additionally, phosphorylation of glycogen synthase kinase-3β and mitogen-activated protein kinase kinase 4, which are upstream kinases of JNK in APAP-induced hepatotoxicity, were also suppressed in Gstm1-null mice. A decrease in liver total glutathione 2 hr after APAP administration, which is an indicator for exposure to N-acetyl-p-benzoquinoneimine, the reactive metabolite of APAP, were similar in wild-type and Gstm1-null mice. In conclusion, Gstm1-null mice are considered to be resistant to APAP-induced hepatotoxicity perhaps by the suppression of JNK phosphorylation. This study indicates the novel role of GSTM1 as a factor mediating the cellular signal for APAP-induced hepatotoxicity.

  10. Relationship of glutathione S-transferase M1 and T1 polymorphisms with the susceptibility of primary angle-closure glaucoma of Chinese Han population in Chongqing%GSTT1和GSTM1基因多态性与重庆地区汉族人群中原发性闭角型青光眼易感性的关系

    Institute of Scientific and Technical Information of China (English)

    陈瑾; 侯胜平; 高小劲; 胡泊; 李平华

    2013-01-01

    Objective To investigate the relationship of genetic polymorphisms of glutathione S-trans-ferase M1 (GSTM1),and glutathione S-transferase T1 (GSTT1) with the susceptibility of primary angleclosure glaucoma in Chinese Han population.Methods Blood samples were collected from 211 Han patients with primary angle-closure glaucoma (PACG) and 422 health volunteers (control),and the 211 PACG patients were separated into an acute PACG (APACG) group and a chronic PACG (CPACG) group according to diagnostic criteria.Furthermore,multiple allele-specific polymerase chain reaction (multiplex PCR) was employed to detect the genetic polymorphisms of GSTT1 and GSTM1.Results The distribution frequencies of GSTT1null genotype were 53.1% and 53.8% in the PACG group and control group,respectively,but no significant difference was found (Chi square =0.028 6,P =0.866).Furthermore,the distribution frequencies of GSTT1-null genotype in the APACG group and CPACG group were 46.3% and 55.4%,respectively,which were not significantly different from that of the control group (Chi square =0.126 7,P =0.722; Chi square =0.036 2,P =0.849).The distribution frequencies of GSTM1-null genotype were 58.3% and 56.3% in the PACG group and control group,respectively,but no significant difference was found (Chi square =0.206 3,P =0.650).The distribution frequencies of GSTM1 were 61.1% and 56.3% in the APACG group and CPACG group,respectively,but no significant difference was found as compared with the control group (Chi square =0.027 9,P =0.867 ; Chi square =0.006 4,P =0.936).Moreover,the combined analysis of GSTT1 and GSTM1 genotypes showed that no significant difference was found in comparison of the four genotypes of GSTT1 and GSTM1 between the PACG (APACG and CPACG) group and control group.Conclusion In Han population with PACG in Chongqing area of China,no relationship is found between the null genotypes of GSTT1 and GSTM1 and PACG susceptibility,and the correlation of genetic

  11. Association of GSTM1 and GSTT1 polymorphisms with noise-induced hearing loss: a meta-analysis%GSTM1和GSTT1基因多态性与听力损失相关性的Meta分析

    Institute of Scientific and Technical Information of China (English)

    周思静; 王苒; 周俊生; 刘胜萍; 周斌; 操磊

    2014-01-01

    目的 了解谷胱甘肽硫转移酶M1(GSTM1)和T1(GSTT1)基因多态性与噪声相关性听力损失的关系.方法 检索Cochrane图书馆、PubMed、OVID、EMBASE、Springer、万方数据库、维普数据库、中国期刊全文数据库及中国生物医学文献数据库,收集GSTM1或GSTT1与噪声相关性听力损失的病例对照研究.按照纳入标准选择文献,提取数据,应用Revman5.0软件进行统计学处理.结果 共纳入中外文献5篇,Meta分析及亚组分析显示,GSTM1缺失型较野生型患噪声相关性听力损失风险增高(缺失型/野生型,OR=1.37,95%CI:1.13~1.66),中国人群GSTM1基因缺失型患噪声相关性听力损失风险增高(OR=1.5,95%CI:1.2~1.86);GSTT1缺失型较野生型发生噪声导致的听力损失风险无明显增高.结论 GSTM1基因多态性与噪声相关性听力损失有关,GSTT1基因多态性与噪声相关性听力损失无关.%Objective To evaluate the association of glutathione S-transferase M1 (GSTM1) and glutathione S-transferase T1 (GSTT1) polymorphisms with noise-induced hearing loss.Methods The Cochrane library,PubMed,OVID,EMBASE,Springer,Wanfang Data,VIP,CNKI,and CBM were searched to collect case-control studies on GSTM1 or GSTT1 polymorphism and noise-induced hearing loss.The articles meeting the inclusion criteria were reviewed systematically,and the reported data were aggregated using Revman 5.0.Results Five studies were included in the meta-analysis.The meta-analysis and subgroup analysis showed that the persons with GSTM 1 null genotype had an increased risk of noise-induced hearing loss compared with those with GSTM1 wild genotype (OR=1.37,95%C1:1.13~1.66); in the Chinese population,the risk of noise-induced hearing loss was higher in persons with GSTM1 null genotype than in those with GSTM1 wild genotype (OR=1.5,95%C1:1.2~1.86); there was no significant difference in the risk of noise-induced hearing loss between persons with GSTT1 null and wild

  12. Dietary intake of vegetables and fruits and the modification effects of GSTM1 and NAT2 genotypes on bladder cancer risk.

    Science.gov (United States)

    Lin, Jie; Kamat, Ashish; Gu, Jian; Chen, Meng; Dinney, Colin P; Forman, Michele R; Wu, Xifeng

    2009-07-01

    We analyzed the association between intakes of vegetables and fruits as defined by the U.S. Department of Agriculture pyramid food groups and bladder cancer risk using data collected in a large case-control study. The study included 884 histologically confirmed bladder cancer cases and 878 healthy controls matched to cases by age (+/-5 years), gender, and ethnicity. Significant inverse associations were observed for intakes of total vegetables, cruciferous vegetables, orange vegetables, dark green vegetables, and bladder cancer risk. Compared with those in the lowest quartile of total vegetable intake, the odds ratios for the 2nd, 3rd, and 4th quartiles of total vegetable intake were 0.84 [95% confidence interval (95% CI), 0.64-1.10], 0.71 (95% CI, 0.54-0.95), and 0.67 (95% CI, 0.50-0.90), respectively (P for trend = 0.004). Compared with those in the lowest quartile, those in the highest quartile of cruciferous vegetable intake had an odds ratio of 0.69 (95% CI, 0.52-0.92; P for trend = 0.001) and those in the highest quartile of orange vegetable intake had an odds ratio of 0.68 (95% CI, 0.52-0.91; P for trend = 0.006). Furthermore, the protective effect of cruciferous vegetables was more evident in subjects carrying GSTM1-null (odds ratio, 0.43; 95% CI, 0.25-0.73 for the 4th quartile of intake) and NAT2-slow genotypes (odds ratio, 0.56; 95% CI, 0.33-0.97 for the 4th quartile of intake). No association was observed for intakes of total fruits or citrus fruits. Our data strongly support that high vegetable consumption, especially cruciferous vegetable intake, may protect against bladder cancer and that genetic variants of GSTM1 and NAT2 may modify the association.

  13. Glutathione S-transferase M1 (GSTM1) genotype but not GSTT1 or MC1R genotype influences erythemal sensitivity to narrow band (TL-01) UVB phototherapy.

    Science.gov (United States)

    Smith, Gillian; Weidlich, Simone; Dawe, Robert S; Ibbotson, Sally H

    2011-04-01

    Although a majority of psoriasis patients respond to treatment with narrow band ultraviolet B radiation (TL-01) phototherapy, it is currently not possible to predict erythemal sensitivity, or to identify treatment responders. A variety of antioxidant enzymes, including the polymorphic glutathione S-transferase GSTM1 and GSTT1 genes, protect the cell from UVR-induced oxidative challenge. GSTM1 and GSTT1 are deleted in approximately 50 and 20% of the Caucasian population, respectively, and GST null genotype has been associated with increased sunburn sensitivity and reduced minimal erythemal dose (MED) after broadband UVR exposure in healthy volunteers and with susceptibility to skin cancer. Another polymorphic determinant of UVR sensitivity is the melanocortin 1 receptor (MC1R), which protects cells from UVR-induced apoptosis and photodamage. Our aim was therefore to investigate whether GST or MC1R genotype influenced erythemal sensitivity to narrow band (TL-01) ultraviolet B radiation phototherapy in patients with psoriasis. We used TaqMan quantitative gene copy and allelic discrimination assays to determine GST and MC1R genotypes, and looked for possible associations between genotype and threshold erythemal sensitivity (MED) and treatment outcomes in patients with psoriasis (n=256). We showed that GSTM1 genotype, but not GSTT1 or MC1R genotype influences erythemal sensitivity to TL-01 phototherapy, with a significantly lower MED observed in GSTM1 null individuals [χ(2 d.f.)=8.862, P=0.012]. None of the genotypes studied were associated with TL-01 treatment outcomes or relapse rates. GSTM1 genotype may have clinical utilityin the prediction of photosensitivity and/or in identifying patients at increased risk of treatment-related side effects.

  14. Broccoli consumption interacts with GSTM1 to perturb oncogenic signalling pathways in the prostate.

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    Maria Traka

    Full Text Available BACKGROUND: Epidemiological studies suggest that people who consume more than one portion of cruciferous vegetables per week are at lower risk of both the incidence of prostate cancer and of developing aggressive prostate cancer but there is little understanding of the underlying mechanisms. In this study, we quantify and interpret changes in global gene expression patterns in the human prostate gland before, during and after a 12 month broccoli-rich diet. METHODS AND FINDINGS: Volunteers were randomly assigned to either a broccoli-rich or a pea-rich diet. After six months there were no differences in gene expression between glutathione S-transferase mu 1 (GSTM1 positive and null individuals on the pea-rich diet but significant differences between GSTM1 genotypes on the broccoli-rich diet, associated with transforming growth factor beta 1 (TGFbeta1 and epidermal growth factor (EGF signalling pathways. Comparison of biopsies obtained pre and post intervention revealed more changes in gene expression occurred in individuals on a broccoli-rich diet than in those on a pea-rich diet. While there were changes in androgen signalling, regardless of diet, men on the broccoli diet had additional changes to mRNA processing, and TGFbeta1, EGF and insulin signalling. We also provide evidence that sulforaphane (the isothiocyanate derived from 4-methylsuphinylbutyl glucosinolate that accumulates in broccoli chemically interacts with TGFbeta1, EGF and insulin peptides to form thioureas, and enhances TGFbeta1/Smad-mediated transcription. CONCLUSIONS: These findings suggest that consuming broccoli interacts with GSTM1 genotype to result in complex changes to signalling pathways associated with inflammation and carcinogenesis in the prostate. We propose that these changes may be mediated through the chemical interaction of isothiocyanates with signalling peptides in the plasma. This study provides, for the first time, experimental evidence obtained in humans to

  15. 原发性闭角型青光眼易感性与GSTM1和GSTT1基因多态性的关系%Relationship of susceptibility of primary angle-closure glaucoma with glutathione S-transferase T1 and M1 polymorphisms

    Institute of Scientific and Technical Information of China (English)

    罗丽丹

    2015-01-01

    目的:研究原发性闭角型青光眼易感性与谷胱甘肽硫转移酶T1( GSTT1)与谷胱甘肽硫转移酶M1( GSTM1)的关系。  方法:将300例原发性闭角型青光眼患者作为观察对象,同时随机选择300例健康志愿者的血液标本作为对照,并将观察组患者分为慢性、急性两亚组,采用PCR技术检测GSTM1和GSTT1基因多态性。  结果:GSTT1缺失基因型在观察组中的分布频率为54.3%,在对照组的分布频率为54.0%,两组差异无统计学意义(χ2=0.053, P>0.05);观察组中慢性组GSTT1缺失基因型分布频率为54.9%,急性组GSTT1缺失基因型分布频率为48.6%,急性组与对照组相比,差异无统计学意义(χ2=0.064,P>0.05),慢性组与对照组差异无统计学意义(χ2=0.037,P>0.05);观察组GSTM1缺失基因型分布频率为59.0%,对照组为55.7%,两组差别无统计学意义(χ2=0.013, P>0.05);GSTM1缺失基因型在观察组急性和慢性两亚组的分布频率分别为62.3%和58.1%,慢性组与对照组差异无统计学意义(χ2=0.047,P>0.05),急性组与对照组差异无统计学意义(χ2=0.005,P>0.05)。  结论:原发性闭角型青光眼易感性与GSTM1和GSTT1基因多态性间不存在明显相关性。%•AlM:To investigate the relationship of susceptibility of primary angle- closure glaucoma with glutathione S-transferase T1 ( GSTT1 ) and M1 ( GSTM1 ) polymorphisms. • METHODS: Totally, 300 cases were collected from primary angle-closure glaucoma patients and 300 health volunteers were served as control group. The observation group were divided into chronic and acute primary angle-closure glaucoma groups, then multiplex PCR technology was used to detect the genetic polymorphisms of GSTM1 and GSTT1. •RESULTS:The distribution frequencies of GSTT1-null genotype were 54. 3%, while it was 54. 0% in the control group, statistically no significance between control group and observation group (χ2 = 0. 053, P > 0. 05 ) ; The frequency GSTT

  16. Lack of participation of the GSTM1 polymorphism in cervical cancer development in Northeast Thailand.

    Science.gov (United States)

    Natphopsuk, Sitakan; Settheetham-Ishida, Wannapa; Settheetham, Dariwan; Ishida, Takafumi

    2015-01-01

    The potential association between the GSTM1 deletion polymorphism and risk of cervical cancer was investigated in Northeastern Thailand. DNA was extracted from buffy coat specimens of 198 patients with squamous cell carcinoma of the cervix and 198 age-matched healthy controls. Genotyping of the GSTM1 was conducted by using two PCR methods, a short- and a long-PCR. Distribution of the GSTM1 genotypes in between the cases and the controls was not significantly different (p>0.5 by χ2 test). The results suggest that the GSTM1 deletion polymorphism is not a risk factor for squamous cell carcinoma of the cervix in the northeast Thai women.

  17. Relationship of tobacco smoking, CYP1A1, GSTM1 gene polymorphism and esophageal cancer in Xi'an

    Institute of Scientific and Technical Information of China (English)

    An-Hui Wang; Chang-Sheng Sun; Liang-Shou Li; Jiu-Yi Huang; Qing-Shu Chen

    2002-01-01

    AIM: To analyze the association of tobacco smoking,polymorphism of CYP1A1 (7th exon ) and GSTM1 genotypeand esophageal cancer(EC) in Xi'an.METHODS: A hospital based case-control study, withmolecular epidemiological method, was carried out.Polymorphism of CYP1A1 and GSTM1 of samples from 127EC cases and 101 controls were detected by PCR method.RESULTS: There were no significant difference of age andgender between cases and controls. Tobacco smokingwas the main risk factor(OR= 1.97 ;95% Cl = 1.12-3.48)for EC in Xi'an. The proportions of CYP1A1 lle/lle, lle/Val and Val/Val gene types in cases and controls was19.7%, 45.7%, 34.6% and 30.7%, 47.5%, 21.8%respectively( P= 0.049). Individuals with CYP1A1 Val/Valgenotype compared to those with CYP1A1 lle/llegenotype had higher risk for EC increased (OR = 2.48,95% Cl = 1.12-5.54). The proportions of GSTM1 deletiongenotype in cases and controls were 58.3% and 43.6%(OR= 1.81, 95%Cl = 1.03-3.18, P = 0.028). Analysis ofgene-environment interaction showed that tobaccosmoking and CYP1A1 Val/Val genotype; tobacco smokingand GSTM1 deletion genotype had synergism interactionrespectively. Analysis of gene-gene interaction did notfind synergistic interaction between these two genes. Butin GSTM1 deletion group, there was significant differenceof distribution of CYP1A1 genotype between cases andcontrols (P=0.011).CONCLUSION: CYP1A1 Val/Val and GSrM1 deletiongenotypes are genetic susceptibility biomarkers for EC. Therisk increases, when person with CYP1A1 Val/Val and/orGSTM1 deletion genotype. And these two-metabolic enzymesseem to have interactions with tobacco smoking, in which themechanism still needs further study.

  18. Joint effect among p53, CYP1A1, GSTM1 polymorphism combinations and smoking on prostate cancer risk: an exploratory genotype-environment interaction study%p53、CYP1A1、GSTM1多态性组合和吸烟对前列腺癌风险的联合效应:基因型和环境相互作用的探测性研究

    Institute of Scientific and Technical Information of China (English)

    Luis A.Qui(n)ones; Carlos E.Irarrázabal; Claudio R.Rojas; Cristian E.Orellana; Cristian Acevedo; Christian Huidobro; Nelson E.Varela; Dante D.Cáceres

    2006-01-01

    Aim: To assess the role of several genetic factors in combination with an environmental factor as modulators of prostate cancer risk. We focus on allele variants of low-penetrance genes associated with cell control, the detoxification processes and smoking. Methods: In a case-control study we compared people carrying p53cd72 Pro allele,CYP1A1 M1 allele and GSTM1 null genotypes with their prostate cancer risk. Results: The joint risk for smokers carrying Pro* and M1*, Pro* and GSTMlnull or GSTM1 null and CYP1A1 M1* variants was significantly higher (odds ratio [OR]: 13.13, 95% confidence interval [CI]: 2.41-71.36; OR: 3.97, 95% CI: 1.13-13.95 and OR: 6.87,95% CI: 1.68-27.97, respectively) compared with that for the reference group, and for non-smokers was not significant.OR for combinations among p53cd72, GSTM1 and CYP1A1 M1 in smokers were positively and significantly associated with prostate cancer risk compared with non-smokers and compared with the putative lowest risk group (OR: 8.87, 95% CI: 1.25-62.71). Conclusion: Our results suggest that a combination of p53cd72, CYP1A1, GSTM1 alleles and smoking plays a significant role in modified prostate cancer risk on the study population, which means that smokers carrying susceptible genotypes might have a significantly higher risk than those carrying non-susceptible genotypes.%目的:评估若干遗传学因素与一个环境因素对患前列腺癌风险的联合调节作用.本文重点关注与细胞调控有关的低外显基因的等位变体、解毒过程和吸烟这几个因素.方法:本研究设了病例对照.研究分析了携p53cd72 Pro等位基因、CYP1A1 M1等位基因和GSTM1 null基因型的人群与他们患前列腺癌的风险之间的关联.结果:携Pro*和M1*,Pro*和GSTM1null或GSTM1 null和CYP1A1 M1*等位变体的吸烟者的联合患病风险显著高于对照组(优势比[odds ratio:OR]:13.13,95%置信区间[CI]:2.41-71.36;OR:3.97,95%CI:1.13-13.95;OR:6.87,95%CI:1.68-27.97),非吸烟组的

  19. GSTM1, GSTT1, and GSTP1 polymorphisms, breast cancer risk factors and mammographic density in women submitted to breast cancer screening Polimorfismos GSTM1, GSTT1 e GSTP1, fatores de risco para câncer de mama e densidade mamográfica em mulheres submetidas a rastreamento mamográfico

    Directory of Open Access Journals (Sweden)

    Ernestina Silva de Aguiar

    2012-06-01

    Full Text Available Genetic polymorphisms in genes related to the metabolism of xenobiotics, such as genes of the glutathione S-transferases (GSTM1, GSTT1, and GSTP1 superfamily have been associated with an increased risk for breast cancer (BC. Considering the high incidence of BC in the city of Porto Alegre in southern Brazil, the purpose of this study was to characterize genotypic and allelic frequencies of polymorphisms in GSTM1, GSTT1, and GSTP1, and correlate these molecular findings with established risk factors for breast cancer including mammographic density, in a sample of 750 asymptomatic women undergoing mammographic screening. Molecular tests were performed using the multiplex polymerase chain reaction (PCR for GSTM1 and GSTT1, and quantitative PCR for GSTP1 polymorphisms. Overall, the frequencies of GSTM1 and GSTT1 null genotypes were 45% and 21%, respectively. For GSTP1 polymorphism, genotypic frequencies were 44% for the Ile/Ile genotype, 44% for the Ile/Val genotype, and 12% for Val/Val genotype, with an allelic frequency of 66% for the wild type allele in this population, similar to results of previous international publications. There was a statistically significant association between the combined GSTM1 and GSTT1 null genotypes (M-/T- and mammographic density in post menopausal women (p = 0.031. When the GSTT1 null (T- genotype was analyzed isolated, the association with mammographic density in post menopausal women and in the overall sample was also statistically significant (p = 0.023 and p = 0.027, respectively. These findings suggest an association of GSTM1 and GSTT1 null genotypes with mammographic density.Polimorfismos genéticos em genes relacionados com o metabolismo de xenobióticos, como os genes da superfamília das glutationa S-transferases (GSTM1, GSTT1 e GSTP1 têm sido associados com o aumento do risco para câncer de mama (CM. Considerando a alta incidência de CM na cidade de Porto Alegre, região Sul do Brasil, a proposta deste

  20. Association between Glutathione S-Transferase GSTM1-T1 and P1 Polymorphisms with Metabolic Syndrome in Zoroastrians in Yazd, Iran

    Science.gov (United States)

    AFRAND, Mohammadhosain; BASHARDOOST, Nasrollah; SHEIKHHA, Mohammad Hasan; AFKHAMI-ARDEKANI, Mohammad

    2015-01-01

    Background: The aim of this study was to assess the possible association between genetic polymorphisms of the glutathione S-transferase (GST) gene family and the risk of the development of metabolic syndrome (MS) in Zoroastrian females in Yazd, Iran. Methods: In this case-control study, GSTM1, T1, and P1 polymorphisms were genotyped in 51 randomly selected MS patients and 50 randomly selected healthy controls on February 2014 among Zoroastrian females whose ages ranged from 40 to 70 yr. DNA was extracted from peripheral blood. Data were analyzed with SPSS version 17. Results: We observed a significant association of GSTP1-I/V (Isoleucine/Valine) allele and GSTP1-V/V (Valine / Valine) allele with MS (P = 0.047 and P = 0.044, respectively). The combined analysis of the two genotypes, the present genotype of GSTT1, I/V and V/V alleles of GSTP1 genotype demonstrated a decrease in the risk of acquiring MS (OR = 0.246, P = 0.031). The null genotype of GSTM1, I/V, and V/V alleles of the GSTP1 genotype showed a lower risk in double combinations (OR = 0.15, P = 0.028 and OR = 0.13, P = 0.013, respectively). The combinations of the GSTM1 null genotypes and GSTT1 present genotypes and the GSTP1 I/V and V/V alleles together were associated with decreased risk of having MS in triple combinations (OR = 0.071, P = 0.039 and OR = 0.065, P = 0.022, respectively). Conclusion: GSTP1-I/V and V/V alleles, alone or in association with GSTM1 null and GSTT1 present genotypes, are related with decreased susceptibility to the development of MS in Zoroastrian females. PMID:26284209

  1. Association between Glutathione S-Transferase GSTM1-T1 and P1 Polymorphisms with Metabolic Syndrome in Zoroastrians in Yazd, Iran.

    Directory of Open Access Journals (Sweden)

    Mohammadhosain Afrand

    2015-05-01

    Full Text Available The aim of this study was to assess the possible association between genetic polymorphisms of the glutathione S-transferase (GST gene family and the risk of the development of metabolic syndrome (MS in Zoroastrian females in Yazd, Iran.In this case-control study, GSTM1, T1, and P1 polymorphisms were genotyped in 51 randomly selected MS patients and 50 randomly selected healthy controls on February 2014 among Zoroastrian females whose ages ranged from 40 to 70 yr. DNA was extracted from peripheral blood. Data were analyzed with SPSS version 17.We observed a significant association of GSTP1-I/V (Isoleucine/Valine allele and GSTP1-V/V (Valine / Valine allele with MS (P = 0.047 and P = 0.044, respectively. The combined analysis of the two genotypes, the present genotype of GSTT1, I/V and V/V alleles of GSTP1 genotype demonstrated a decrease in the risk of acquiring MS (OR = 0.246, P = 0.031. The null genotype of GSTM1, I/V, and V/V alleles of the GSTP1 genotype showed a lower risk in double combinations (OR = 0.15, P = 0.028 and OR = 0.13, P = 0.013, respectively. The combinations of the GSTM1 null genotypes and GSTT1 present genotypes and the GSTP1 I/V and V/V alleles together were associated with decreased risk of having MS in triple combinations (OR = 0.071, P = 0.039 and OR = 0.065, P = 0.022, respectively.GSTP1-I/V and V/V alleles, alone or in association with GSTM1 null and GSTT1 present genotypes, are related with decreased susceptibility to the development of MS in Zoroastrian females.

  2. Association of GSTM1, GSTT1, GSTP1-ILE105VAL and ACE I/D polymorphisms with ankylosing spondylitis.

    Science.gov (United States)

    İnal, Esra Erkol; Görükmez, Orhan; Eroğlu, Selma; Görükmez, Özlem; Solak, Özlem; Topak, Ali; Yakut, Tahsin

    2016-01-01

    Ankylosing spondylitis (AS) is a chronic inflammatory disease of unknown origin. The aim of this study is to clarify the relationships between susceptibility and severity of AS and GST-mu1 (GSTM1), GST-theta1 (GSTT1), GST-pi1 (GSTP1)-Ile105Val and angiotensin-converting enzyme (ACE) I/D polymorphisms in AS patients. One hundred thirty-eight AS patients and seventy-one healthy controls were enrolled in this study. Erythrocyte sedimentation rate and C-reactive protein (CRP) levels of the AS patients were recorded. The scores of the numeric rating scale (NRS) pain, the Bath Ankylosing Spondylitis Activity Index, the Bath Ankylosing Spondylitis Metrology Index and the Bath Ankylosing Spondylitis Functional Index were calculated. The genotypes distributions and allele frequencies of GSTM1, GSTT1, GSTP1-Ile105Val and ACE I/D polymorphisms were compared between patients and healthy controls. The Multiplex polymerase chain reaction (PCR) and the PCR-restriction fragment length polymorphism methods were used to detect the polymorphisms of ACE I/D, the GSTT1 and GSTM1 genes and the GSTP1-Ile105Val polymorphism, respectively. There were significantly higher levels of the GSTT1 null and the ACE II genotypes in AS patients compared to those in healthy controls (p = 0.002 and 0.005, respectively). We found significantly higher levels of CRP and the NRS pain scores in the patients with ACE ID or DD genotypes compared to those in the patients with ACE II genotypes (p = 0.005 and 0.035, respectively). The present results showed that genes involved in protection from oxidative stress and ACE gene may influence disease development and course in AS.

  3. 南京地区青年乳腺癌患者GSTM1、GSTT1基因多态性与易感性的初步研究%A Preliminary Study on the Relationship between Genetic Polymorphism of Glutathione-S transferases T1, M1genes and Susceptibility of Young Female Breast Cancer in Nanjing Area

    Institute of Scientific and Technical Information of China (English)

    范滨; 唐金海; 吴建中; 王卓; 薛琏

    2012-01-01

    目的:研究GSTM1、GSTT1基因多态性与乳腺癌遗传易感性的关系.方法:应用PCR技术检测乳腺癌组和对照组人群GSTM1和GST T1基因.结果:GSTM 1和GSTT 1基因缺失率在乳腺癌组分别为63.4%(59/93)和54.8%(51/93),对照组分别为39.3% (35/89)和33.7% (30/89),两组比较,差异有统计学意义(P<0.01或P<0.05).结论:GSTM1和GST T1缺失为乳腺癌遗传易感因素.%Objective: To examine the relationship of genetic polymorphisms of glutathione S-transferase (GST) including GSTM1 and GSTT1 and the susceptibility to breastcancer. Methods: A case-control study was designed and the absence of GSTM 1 and GSTT1 genes were detected with PCR technique in 93 cases and 89 conrols. Results: The results showed that the ratios of GSTM1 null genotype in cases was 63. 4%(59/ 93) and the ratios of GSTT1 null genotype in cases was 54. 8%(51/93), while, those of controls were 39.3% (35/ 89) or 33.7% (30/89), P< 0.05. Conclusion: GSTM1 and GSTT1 null may be an important host risk factor for breastcancer.

  4. CYP1A1 and GSTM1 polymorphisms in relation to lung cancer risk in Chinese women

    Energy Technology Data Exchange (ETDEWEB)

    Yang, X.H.R.; Wacholder, S.; Xu, Z.Y.; Dean, M.; Clark, V.; Gold, B.; Brown, L.M.; Stone, B.J.; Fraumeni, J.F.; Caporaso, N.E. [NCI, Bethesda, MD (US). Division of Epidemiology and Genetics

    2004-10-28

    We examined CYP1A1 (1462V) and GSTM1 null polymorphisms in 200 female cases and 144 female controls selected from a population-based case-control study of lung cancer conducted in northeast China, where the rates of lung cancer among Chinese women are especially high. The CYP1A1 codon 462 point mutation in exon 7 (I462V) causes an Ile-Val substitution near the heme binding site. This mutation correlates with inducibility of aryl hydrocarbon hydrolase (AHH) activity, which activates polycyclic aromatic hydrocarbons (PAHs) in tobacco smoke and in indoor air pollution from coal-burning stoves, a risk factor for lung cancer in this study population. We found that the CYP1A1 I462V genotype (combined ile/val and val/val) was significantly associated with lung cancer risk. The odds ratio (OR) was 2.5 (95% confidence interval (CI), 1.55-4.03) after adjustment for significant risk factors such as age, ever smoking status, family history of cancer, and eye irritation when cooking. The association was more pronounced among non-smokers (OR= 3.67; 95% Cl, 1.85-7.28) than among smokers (OR= 1.74, 95% CI, 0.85-3.54). In contrast, we did not find a significant association with the GSTM1 null genotype. In summary, our case-control study of lung cancer among women in northeast China revealed an elevated risk associated with the CYP1A1 I462V genotype, but no interaction with smoking or indoor air pollution was found.

  5. Glutathione S-transferase M1 null genotype related to poor prognosis of colorectal cancer.

    Science.gov (United States)

    Yan, Shushan; Wang, Zengfang; Wang, Zengyan; Duan, Quanhong; Wang, Xiaochen; Li, Jun; Sun, Beicheng

    2016-08-01

    Published studies showed controversial findings about the relationship between glutathione S-transferase M1 (GSTM1) null genotype and clinical outcomes of patients with colorectal cancer. We performed a meta-analysis to quantitatively assess the association between GSTM1 null genotype and prognosis of patients with colorectal cancer. We systematically searched Pubmed, Embase, and Web of Science to identify prospective or retrospective cohort studies assessing the association of GSTM1 null genotype with overall survival (OS) or disease-free survival (DFS) in colorectal cancer. The hazard ratios (HRs) and 95 % confidence intervals (95 % CIs) were used to assess the association of GSTM1 null genotype with OS or DFS. Finally, 15 studies from 14 publications with 4326 colorectal cancer patients were included into the meta-analysis. There was no heterogeneity in the meta-analysis relating OS (I (2) = 0 %) and DFS (I (2) = 0 %). Overall, GSTM1 null genotype was significantly associated with poor OS in patients with colorectal cancer (HR = 1.18, 95 % CI 1.07-1.30, P = 0.001). In addition, GSTM1 null genotype was also significantly associated with poor DFS in patients with colorectal cancer (HR = 1.15, 95 % CI 1.03-1.28, P = 0.015). No obvious risk of publication bias was observed. GSTM1 null genotype is significantly associated with poor OS and DFS in patients with colorectal cancer, which suggests that GSTM1 null genotype confers poor effect on the prognosis of colorectal cancer.

  6. GSTM1, GSTT1, GSTP1 and CYP1A1 genetic polymorphisms and susceptibility to esophageal cancer in a French population:Different pattern of squamous cell carcinoma and adenocarcinoma

    Institute of Scientific and Technical Information of China (English)

    Ahmed Abbas; Karine Delvinquière; Mathilde Lechevrel; Pierre Lebailly; Pascal Gauduchon; Guy Launoy; Fran(c)ois Sichel

    2004-01-01

    AIM: To evaluate the association between CYP1A1 and GSTs genetic polymorphisms and susceptibility to esophageal squamous cell carcinoma (SCC) and esophageal adenocarcinoma (ADC) in a high risk area of northwest of France.METHODS: A case-control study was conducted to investigate the genetic polymorphisms of these enzymes (CYP1A1 *2C and GSTP1 exon 7 Val alleles, GSTM1*2/*2and GSTT1*2/*2 null genotypes). A total of 79 esophageal cancer cases and 130 controls were recruited.RESULTS: GSTM1*2/*2 and CYP1A1*1A/*2C genotype frequencies were higher among squamous cell carcinomas at a level close to statistical significance (OR = 1.83, 95% CI 0.88-3.83, P= 0.11; OR = 3.03, 95% CI 0.93-9.90, P= 0.07,respectively). For GSTP1 polymorphism, no difference was found between controls and cases, whatever their histological status. Lower frequency of GSTT1 deletion was observed in ADC group compared to controls with a statistically significant difference (OR = 13.31, 95% CI 1.66-106.92, P<0.01).CONCLUSION: In SCC, our results are consistent with the strong association of this kind of tumour with tobacco exposure. In ADC, our results suggest 3 distinct hypotheses:(1) activation of exogenous procarcinogens, such as small halogenated compounds by GSTT1; (2) contribution of GSTT1 to the inflammatory response of esophageal mucosa, which is known to be a strong risk factor for ADC,possibly through leukotriene synthesis; (3) higher sensitivity to the inflammatory process associated with intracellular depletion of glutathione.

  7. 谷胱甘肽S-转移酶GSTT1、GSTM1基因多态性与老年性耳聋遗传易感性的关联性分析%Association analysis of GSTT1 and GSTM1 genes with hereditary susceptibility to age-related hearing loss among Chinese

    Institute of Scientific and Technical Information of China (English)

    朱玉华; 戴朴; 袁慧军; 翟所强

    2011-01-01

    Objective To determine the relationship between GSTM1 and GSTT1 genetic polymorphisms and hereditary susceptibility to age-related hearing loss. Methods Specimens in this study were selected from the database at the Deafness Molecular Diagnosis Center, Institute of Otorhinolaryngology, Chinese PLA General Hospital for genomic DNA extraction. The genetic polymorphisms of GSTM1 and GSTT1 were detected by multiplex polymerase chain reaction. The results were compared to the control and x2 test was used to determine the frequency and association of genotype of GSTM1 and GSTT1. Results This study included 224 specimens, including those from cases of age-related hearing loss (n= 110, PTA = 51 ± 11 dB HL) and from age-matched controls(n= 114, PTA = 18±4dB HL) All subjects were between 60° to 80 years of age. The average age of the age related hearing loss group (77 males and 33 females) was 72.93 ± 5.08 years, and that of the control group (76 males and 38 females) was 73.10 ± 5.787 years. Cenotyping and statistical analysis revealed no difference between patients with age related hearing loss and the controls regarding GSTM1, GSTT1 genotype positive rate and frequencies of GSTT1+/GSTW+, GSTT1+/GSTM1-, GSTT1-/GSTT1+ and GSTT1-/GSTM1- genotypes (P> 0.05). Conclusion We are unable to detect a strong association between GSTM1, GSTT1 gene and age related hearing loss in this Chinese population.%目的 探讨谷胱甘肽S-转移酶(glutathione S-transferase,GST)GSTT1和GSTM1基因多态性是否与老年性耳聋遗传易感性相关.方法 在解放军总医院耳鼻咽喉科研究所聋病分子诊断中心样本库中选取本研究的研究对象,提取基因组DNA;利用多重PCR(Polymerase chain reaction,PCR)的方法 同时扩增所有研究对象GSTT/GSTM基因编码区并进行GSTM1和GSTT1基因多态性的分型;通过病例-对照关联性分析方法 进行统计学分析,明确GSTT1和GSTM1的多态性和老年性耳聋遗传易感性是否相关.结果

  8. Association between glutathione S-transferase M1 null genotype and risk of gallbladder cancer: a meta-analysis.

    Science.gov (United States)

    Sun, Hong-Li; Han, Bing; Zhai, Hong-Peng; Cheng, Xin-Hua; Ma, Kai

    2014-01-01

    Glutathione S-transferases (GSTs) are a family of enzymes which are involved in the detoxification of potential carcinogens. Glutathione S-transferase M1 (GSTM1) null genotype can impair the enzyme activity of GSTs and is suspected to increase the susceptibility to gallbladder cancer. Previous studies investigating the association between GSTM1 null genotype and risk of gallbladder cancer reported inconsistent findings. To quantify the association between GSTM1 null genotype and risk of gallbladder cancer, we performed a meta-analysis of published studies. We searched PubMed, Embase, and Wanfang databases for all possible studies. We estimated the pooled odds ratio (OR) with its 95% confidence interval (95% CI) to assess the association. Meta-analysis of total included studies showed that GSTM1 null genotype was not associated with gallbladder cancer risk (OR = 1.13, 95% CI 0.88-1.46, P = 0.332). Subgroup analysis by ethnicity showed that there was no association between GSTM1 null genotype and risk of gallbladder cancer in both Caucasians and Asians. However, meta-analysis of studies with adjusted estimations showed that GSTM1 null genotype was associated with increased risk of gallbladder cancer (OR = 1.46, 95% CI 1.02-2.09, P = 0.038). Thus, this meta-analysis shows that GSTM1 null genotype is likely to be associated with risk of gallbladder cancer. More studies with well design and large sample size are needed to further validate the association between GSTM1 null genotype and gallbladder cancer.

  9. Detection of GSTM1, GSTT1 and the Ile105Val GSTP1 gene variants

    DEFF Research Database (Denmark)

    Buchard, Anders; Sanchez, Juan J.; Dalhoff, Kim;

    2008-01-01

    We have developed a PCR multiplex method that in a fast, inexpensive and reliable manner can detect if a person has two, one or no GSTM1 and GSTT1 genes and which at the same time can detect the allelic status of the GSTP1 Ile105Val genetic variant. A total of 200 Danes, 100 Somalis and 100 Green...

  10. Cigarette smoking, dietary habits and genetic polymorphisms in GSTT1, GSTM1 and CYP1A1 metabolic genes: A case-control study in oncohematological diseases

    Science.gov (United States)

    Cerliani, María Belén; Pavicic, Walter; Gili, Juan Antonio; Klein, Graciela; Saba, Silvia; Richard, Silvina

    2016-01-01

    AIM To analyze the association between oncohematological diseases and GSTT1/GSTM1/CYP1A1 polymorphisms, dietary habits and smoking, in an argentine hospital-based case-control study. METHODS This hospital-based case-control study involved 125 patients with oncohematological diseases and 310 control subjects. A questionnaire was used to obtain sociodemographic data and information about habits. Blood samples were collected, and DNA was extracted using salting out methods. Deletions in GSTT1 and GSTM1 (null genotypes) were addressed by PCR. CYP1A1 MspI polymorphism was detected by PCR-RFLP. Odds ratio (OR) and 95%CI were calculated to estimate the association between each variable studied and oncohematological disease. RESULTS Women showed lower risk of disease compared to men (OR 0.52, 95%CI: 0.34-0.82, P = 0.003). Higher levels of education (> 12 years) were significantly associated with an increased risk, compared to complete primary school or less (OR 3.68, 95%CI: 1.82-7.40, P tobacco, none of the smoking categories showed association with oncohematological diseases. Regarding dietary habits, consumption of grilled/barbecued meat 3 or more times per month showed significant association with an increased risk of disease (OR 1.72, 95%CI: 1.08-2.75, P = 0.02). Daily consumption of coffee also was associated with an increased risk (OR 1.77, 95%CI: 1.03-3.03, P = 0.03). Results for GSTT1, GSTM1 and CYP1A1 polymorphisms showed no significant association with oncohematological diseases. When analyzing the interaction between polymorphisms and tobacco smoking or dietary habits, no statistically significant associations that modify disease risk were found. CONCLUSION We reported an increased risk of oncohematological diseases associated with meat and coffee intake. We did not find significant associations between genetic polymorphisms and blood cancer. PMID:27777882

  11. Polimorfismos en los genes de desintoxicación CYP1A1, CYP2E1, GSTT1 y GSTM1 en la susceptibilidad al cáncer gástrico

    Directory of Open Access Journals (Sweden)

    Auxiliadora González

    2004-09-01

    cancer. Some polymorphisms of those enzymes have been associated specifically with susceptibility to gastric cancer. We conducted a study in a Costa Rican population, where gastric cancer incidence and mortality rates are among the highest in the world. We investigated whether such variations affected the risk of developing gastric cancer. Subjects included 31 with gastric cancer, 58 controls with gastric injures others than cancer and 51 normal controls confirmed by X-rays (double-contrast or endoscopic diagnostic. DNA from peripheral white blood cell was obtained from all subjects. Deletion of GSTT1 and GSTM1 was assessed by multiplex PCR and genotyping of CYP2E1 was performed using a PCR-based restriction fragment length polymorphism assay with the restriction enzyme PstI and the gene CYP1A1 using the restriction enzyme MspI. The prevalence of CYP1A1 MspI polymorphism, GSTT1 and GSTM1 null genotype was similar in the three groups of individuals (p=0.73, p=0.88 y p= 0.89 respectively. Our findings suggest that the polymorphism CYP2E1 PstI could be associated with a reduced risk of having gastric cancer (OR=0.09, IC95% :0.01 - 0.83. Rev. Biol. Trop. 52(3: 591-600. Epub 2004 Dic 15.

  12. Environmental air pollution and DNA adducts in Copenhagen bus drivers - effect of GSTM1 and NAT2 genotypes on adduct level

    DEFF Research Database (Denmark)

    Nielsen, Per Sabro; de Pater, Nettie; Okkels, Henrik

    1996-01-01

    The lymphocyte bulky PAH-DNA adduct levels have been studied in persons occupationally exposed to ambient air pollution. The exposure group consisted of 90 healthy, nonsmoking bus drivers from the Copenhagen area, divided into three exposure groups according to driving area, and 60 rural controls...... to levels of exposure to urban air pollution and indicated that these adducts might be helpful as a means of classifying better different exposure groups for epidemiological studies. Furthermore, it demonstrated the ability of 32P-postlabelling to discern small differences in low exposure to ambient air...... pollution and suggested a possible effect of GSTM1*0/0 on DNA adduct levels....

  13. GSTM1和GSTT1基因多态性对苯乙烯接触工人苯乙烯代谢的影响%Influence of Genetic Polymorphisms of GSTM1 and GSTT1 on Metabolism of Styrene in Styrene-exposed Workers

    Institute of Scientific and Technical Information of China (English)

    张放; 籍继颖; 邵华; 张志虎

    2011-01-01

    目的 探讨GSTM1和GSTT1基因多态性对苯乙烯接触工人苯乙烯代谢的影响.方法于2006年11月选择山东省某玻璃钢游艇生产企业喷漆车间工龄在1年以上、防护情况基本相同的全部工人共计56人作为研究对象.分别测定个体苯乙烯接触剂量、尿中代谢产物——苯乙烯巯基尿酸的浓度,采用多重PCR技术检测GSTM1和GSTT1基因多态性.结果 工人尿中苯乙烯巯基尿酸浓度均值为(19.80±13.25) mg/g Cr,苯乙烯8h时间加权平均浓度(8 h-TWA)均值为(133.28±95.81) mg/m3,两者间呈正相关(r=0.937,P<0.05).高暴露组(苯乙烯浓度>50 mg/m3)和低暴露组(苯乙烯浓度≤50 mg/m3)工人年龄、工龄、吸烟率、饮酒率以及GSTM1、GSTT1基因型的构成比间比较,差异均无统计学意义.无论在低暴露组还是高暴露组,携带GSTM1(+)基因型受试工人尿中的苯乙烯巯基尿酸浓度均高于携带GSTM1(-)基因型受试工人,差异均有统计学意义(P<0.05);但是在携带GSTT1不同基因型受试工人之间中未发现同等差异.结论CSTM1是苯乙烯的主要代谢酶之一,其基因多态性可影响苯乙烯在体内的代谢过程.%Objective To explore the influence of genetic polymorphisms of GSTM1 and GSTT1 on metabolism of styrene in styrene-exposed workers. Methods In November 2006,fifty-six styrene-exposed workers were chosen as the study subjects. Personal passive samplers were used to determine personal 8 -hour -time -weighted average (8h -TWA). The concentration of the phenyl-hydroxyethyl-mercapturic-acid (PHEMA) in urine was determined by Ellman spectrophotometry. The genetic polymorphisms of GSTT1 and GSTMl were detected by multiple PCR method. Results The mean concentration of PHEMA in urine,8-hour-TWA of styrene were (19.80±13.25) mg/g Cr,(133.28±95.81) mg/m3,respectively, with a positive correlation (r=0.937,P50 mg/m3) or low-exposed group (8h-TWAs≤50 mg/m3), there was a significant association between

  14. Correlation of the polymorphism of EC-SOD and GSTM1 and smoking with oral cancer risk%EC-SOD和GSTM1基因多态性及吸烟与口腔癌风险关系研究

    Institute of Scientific and Technical Information of China (English)

    张超贤; 郭李柯; 郭晓凤

    2012-01-01

    Objective To investigate the correlation of the polymorphisms of EC-SOD and GSTMl, as well as smoking, with oral cancer risk. Methods A case-control study and polymerase chain reaction (PCR) technique was used to identify the genotype of EC-SOD and GSTMl in 600 oral cancer cases and 600 controls. Logistic regression was conducted to evaluate the odds ratio of relative gene and the interaction between the genes and smoking with oral cancer. Results The frequencies of EC-SOD genotype in cases and controls were 61.17% and 78.50% for C/C, and 38.33% and 21.50% for C/G respectively (P < 0. 01 ) . EC-SOD ( C/G ) correlated with susceptible to oral cancer (OR =2. 27, 95% CI 1.73 -4.02). The frequency distribution of GSTM1 ( -) was significantly different in patients (69. 17% ) and controls (44. 17% ) (P <0. 01). GSTMl ( - ) increased the risk of developing oral cancer ( OR = 2. 84, 95% C/ 1. 95 - 4. 47 ). Combined polymorphism analysis showed that the percentage of EC-SOD (C/G) /GSTMl ( - ) for oral cancer and control groups was 30. 50% and 6. 67% respectively) (P <0. 01). The risk of developing oral cancer in those with EC-SOD( C/G)/GSTM1( - ) genotype was significantly higher than that with EC-SOD ( C/C )/GSTMl ( + ) genotype ( OR = 8. 16, 95% CI 3. 73 - 12. 91). There were significant differences in smoking rate between the two groups ( P <0. 01) , smoking correlated with susceptible to oral cancer(OR =2.66,95% CI 1.45-4.36), and statistical analysis suggested an interaction between smoking and EC-SOD(C/G)/GSTMl( - ) genotype, which increase the risk of oral cancer (OR = 25. 11, 95% CI 12. 37 - 36. 62). Conclusion EC-SOD(C/G) and GSTMl ( - ) are risk factors in oral cancer. Smoking is also related to the susceptibility to oral cancer. There may be a synergetic interaction among EC-SOD ( C/G) , GSTMl ( - ) and smoking on the elevated susceptibility of oral cancer.%目的 探讨细胞外超氧化物歧化酶( EC-SOD)和谷胱甘肽硫转移酶M1(GSTM1)基因多态性及

  15. Cytochrome P450 (CYP and glutathione S-transferases (GST polymorphisms (CYP1A1, CYP1B1, GSTM1, GSTP1 and GSTT1 and urinary levels of 1-hydroxypyrene in Turkish coke oven workers

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    Ahmet Oguz Ada

    2007-01-01

    Full Text Available Genetic polymorphisms of xenobiotic metabolizing enzymes have been associated with cancer risk. We evaluated the influences of genetic polymorphisms of polycyclic aromatic hydrocarbon (PAH metabolizing enzymes on urinary 1-hydroxypyrene (1-OHP excretion in Turkish coke oven workers. Urinary 1-OHP was analyzed by HPLC after enzymatic hydrolysis. Lymphocyte DNA was used for PCR-based genotyping of cytochrome P450 (CYP polymorphisms (CYP1A1 and CYP1B1 and glutathione S-transferases (GST polymorphisms (GSTM1, GSTT1 and GSTP1. The mean urinary 1-OHP levels of coke oven workers were significantly higher than that of controls. No significant difference was detected in the mean urinary 1-OHP levels of smokers and non-smokers either for coke oven workers or controls. Genetic polymorphisms of the CYPs and GSTs studied had no significant influence on 1-OHP excretion in coke oven workers, but in the control group the urinary 1-OHP levels of individuals carrying the GSTT1- genotype were significantly higher than those of individuals carrying GSTT1+ genotype. The duration of occupational exposure and metabolic genotype for GSTT1 were the significant predictors of urinary 1-OHP levels. The control individuals carrying combined GSTM1-/GSTT1- genotypes also had significantly higher levels of urinary 1-OHP than those of individuals carrying GSTM1+/GSTTI+, GSTM1-/GSTT1+, and GSTM1+/GSTT1- genotypes. These results indicate that urinary 1-OHP is a sensitive indicator of recent human exposure to PAHs and that genetic polymorphism of GSTT1 may also to some extent reflect the interindividual variation in susceptibility to PAHs only at low PAH exposure.

  16. 谷胱甘肽转硫酶M1、T1基因型及烟酒嗜好与胃癌易感性的关系%Influence GSTM1 and GSTT1 Genotypes and Smoking, Alcohol Exposure on the Occurrence of Gastric Cancer: Case-control Study from Nanjing,China

    Institute of Scientific and Technical Information of China (English)

    沈孝兵; 浦跃朴; 张娇; 朱良军

    2005-01-01

    -matched controls, who were selected from Nanjing Zhongda hospital and Jiangsu Province Cancer Hospital. Conditional logistic analysis was performed to elucidate the genetic and environmental risk (smoking and drinking) for gastric cancer. [ Results ] GSTM1 null genotype was more commonly observed in cases, but this was not statistically significant. The frequency of GSTM1 null genotype in cases and controls was 44.63% and 33.88%, respectively (χ2=2.6436, P > 0.05); that of GSTT1 was 52.89% and 44.63% respectively (x2= 1.1650, P > 0.05). Cigarette smoking and alcohol exposure were significantly associated with gastric cancer respectively, and the Odd Ratios(OR) were 2.538 (95%CI: 1.336~4.823) and 1.928 (95%CI: 1.011~3.667 ) respectively. An interaction was observed between GSTM1, GSTT1 genetic types and smoking, alcohol drinking to gastric cancer: People who carry GSTM1(-), GSTF1 (-) were prone to development of gastric cancer; OR=2.097 (95%CI: 1.025~4.291); people co-abused smoking and alcohol had a higher susceptibility to gastric cancer than those non-smoking and non-alcohol drinking, OR=2.330 (95%CI: 1.211~4.482); People who carry GSTM1(-), GSTT1(-) and exposed to smoking and alcohol had a higher susceptibility to gastric cancer than those with GSTM1(+), GSTF1(+) and non-smoking and non-alcohol drinking, (OR=3.600, 95%CI: 1.025-12.650). [ Conclusion ] Smoking and drinking habit are likely associated with the susceptibility to gastric cancer; interaction of GSTM1, GSTF1 genotype and smoking, alcohol drinking exists in the risk of gastric cancer.

  17. Polymorphism of CYPIA1 and GSTM1 genes associated with susceptibility of gastric cancer in Shandong Province of China

    Institute of Scientific and Technical Information of China (English)

    Hao Li; Xue-Liang Chen; Hui-Qing Li

    2005-01-01

    AIM: To explore whether polymorphisms of the CYPIA1 and GSTM1 genes are associated with susceptibility of stomach cancer.METHODS: A total of 102 stomach cancer cases and 62 healthy persons were diagnosed by pathology in 1998-2000 in the Qilu Hospital of Shandong University. Gene polymorphisms were detected by the PCR using sequence-specific primers. Data analysis of the case-control study was carried out using the unconditional logistic method.RESULTS: After adjustment for age, sex, educational levels, and occupation, the risk factors for stomach cancer were shown to be smoking, Helicobacter pylori(H pylori),and presence of the CYPIM G/G and GSTM1 O/O genotypes.Interaction was observed between the combined genotypes of either CYPIA1 G/G and GSTM1 O/O or H pylori infection,or GSTM1 O/O and H pylori infection or smoking.CONCLUSION: Polymorphisms of the CYPIA1 and GSTM1 genes, H pylori infection and smoking are related to susceptibility to stomach cancer.

  18. GSTM1, GSTT1 and GSTP1 gene polymorphism in polymorphous light eruption.

    Science.gov (United States)

    Zirbs, M; Pürner, C; Buters, J T M; Effner, R; Weidinger, S; Ring, J; Eberlein, B

    2013-02-01

    Polymorphous light eruption (PLE) is the most common chronic and idiopathic photodermatosis. PLE is assumed to represent an immunological hypersensitivity reaction to a radiation-induced cutaneous antigen involving reactive oxygen species (ROS) on the basis of a genetic predisposition. Among others, cellular protection against ROS is provided by glutathione S-transferases (GSTs). Different variants of the GST enzymes may influence the activity and efficiency of detoxification and biotransformation of unknown UV-induced skin-antigens and other factors that may play an important role in the pathogenesis of PLE. In this study the relationship between isoenzymes of the GST genes GSTM1, GSTT1 and GSTP1 and possible protective or predisposing effects on PLE was examined in 29 patients and 144 controls. Diagnosis of PLE was based on the presence of characteristic clinical features. No association between the functional polymorphisms of the GST gene family and PLE was found. Prevalence of certain GST isoenzymes or polymorphisms in patients with PLE did not differ from healthy controls. Our data do not support prevalence of GST isoenzymes or polymorphisms as a protective effect against PLE. Especially a higher carrier frequency of GSTP1 Val(105) as a protective factor against PLE which has been published before could not be proved. The GST genotypes GSTM1, GSTT1 and GSTP1 (including SNPs) seem to have no relevant association with PLE. © 2012 The Authors. Journal of the European Academy of Dermatology and Venereology © 2012 European Academy of Dermatology and Venereology.

  19. Clinical and pathological implications of GSTM1 and GSTT1 gene deletions in sporadic breast cancer

    Directory of Open Access Journals (Sweden)

    Maria Salete Costa Gurgel

    2011-12-01

    Full Text Available There is a lack of consensus about the influence of GST M1/T1 gene deletions (DEL on sporadic breast cancer (SBC. To evaluate the occurrence of DEL in 177 SBC cases and in 169 controls, and compare clinical and biological characteristics. A lower frequency of GSTM1 DEL was observed in mulatto women, OR=0.48 (0.24–0.98. The risk of nuclear grade 3 tumors (GN3 was lower in patients with GSTT1 DEL, OR=0.37 (0.15–0.90. DEL of at least one gene (ALOG was associated with women who had not breastfed, OR=0.41 (0.19–0.88, and with negative hormone receptor, HR–, ORadj=2.25 (1.03–4.90. Both genes deleted (BGD was associated with non-classic invasive ductal carcinoma (NCDC, ORadj=12.09 (1.03–142.03. Mulatto women with SBC had a lower frequency of GSTM1 DEL, while tumors differentiated were related to GSTT1 DEL. HRtumors were related with DEL ALOG, and the BGD was associated with a greater risk of NCDC.

  20. Dependence of Papanicolaou gradings of exfoliated urothelial cells upon GSTM1 and GSTT1 polymorphism in benzidine-exposed workers of the Shanghai dye industry

    Energy Technology Data Exchange (ETDEWEB)

    Lin Guofang; Ma Qingwen; Shen Jianhua; Zhang Dongsheng [Shanghai Inst. of Biological Sciences, Chinese Academy of Sciences, Shanghai (China); Chen Jigang; Xiang Cuiqing [Municipal Center for Disease Prevention and Control, Shanghai (China); Golka, K. [Institute of Occupational Physiology, Univ. of Dortmund (Germany)

    2001-11-01

    The distribution of the polymorphic alleles of the genes coding for glutathione S-transferases (GSTs) M1 and T1 was compared with the results of cytological grading of exfoliated urothelial cells (Pap test) in a non-diseased high-risk group of workers formerly exposed to benzidine in the Shanghai dyestuff industry (n=317). All subjects were genotyped for GSTT1 and M1 gene polymorphism by allele-specific PCR. Individuals were stratified according to their job and duration of exposure. A subgroup of 78 individuals with cytological gradings of grade III or higher in the Pap test showed a significant under-representation of the combination of GSTT1 0/0 and M1 0/0 genotypes compared with 238 subjects with a cytological classification lower than grade III (OR 0.55, 95% CI 0.31-0.98, P=0.04). These results suggest that neither the GSTM1 0/0 or GSTT1 0/0 genotype alone nor their combination had a clear association with cytopathological changes in exfoliated urothelial cells from individuals previously exposed to benzidine in Shanghai. This contradicts the results of studies indicating that the GSTM1 0/0 genotype is associated with an increased risk for bladder cancer in the general population, mostly outside China. (orig.)

  1. Association of the ACE, GSTM1, IL-6, NOS3, and CYP1A1 polymorphisms with susceptibility of mycoplasma pneumoniae pneumonia in Chinese children.

    Science.gov (United States)

    Zhao, Jie; Zhang, Wen; Shen, Li; Yang, Xiaomeng; Liu, Yi; Gai, Zhongtao

    2017-04-01

    Mycoplasma pneumoniae is a common cause of community-acquired pneumonia (CAP) and the clinical presentation of mycoplasma pneumoniae pneumonia (MPP) varies widely. Genetic variability affecting the host response may also influence the susceptibility to MPP. Several studies have investigated the association between single nucleotide polymorphism (SNP) of some genes and the risks of CAP; however, the results were inconsistent. Here, we investigated the association of 5 functional genes and the risks of MPP, including ACE (rs4340), GSTM1 (Ins/del), IL-6 (rs1800795), NOS3 (rs1799983), and CYP1A1 (rs2606345) in a total of 715 subjects (415 cases, 300 controls) by using tetra-primer allele-specific polymerase chain reaction (PCR) and Sanger sequencing. The gene-gene interactions were analyzed using the Multifactor Dimensionality Reduction and cumulative genetic risk score approaches. Our results showed that 3 SNPs of ACE rs4340, IL-6 rs1800795, and NOS3 rs1799983 were significantly associated with the risks of MPP, while no differences were observed in genotype frequencies of GSTM1 (Ins/del) and CYP1A1 rs2606345 between both groups. The combinations of ACE rs4340D/NOS3 rs1799983T/CYP1A1 rs2606345G and ACE rs4340D/NOS3 rs1799983T contribute to the genetic susceptibility of MPP in Chinese children.

  2. Genetic polymorphism of GSTM1 to lung cancer patients in north Sichuan of China%中国四川北部肺癌患者谷胱苷肽硫转移酶M1基因多态性分析

    Institute of Scientific and Technical Information of China (English)

    马代远; 杜国波; 谭榜宪; 柳弥; 赵妍丽; 杨明辉

    2011-01-01

    Objective To analyze the genetic polymorphism of GSTM1 to lung cancer patients in north Sichuan of China and compare with race from other district.Methods PCR-based technique was used to detect the genotypes of GSTM1 in lung cancer patients.Results In local lung cancer patients,the frequency of homozygous deletions(null genotype) for GSTM1 was 58.4 % (73/125).Among the patients,the frequencys of null genotype for GSTM1 were 62.5 % (20/32) in female,56.9 % (53/93) in male,56.1% (32/57)in patients with squamous cell carcinoma and 54.8 % (17/31) in patients with adenocarcinoma,respectively.The frequency of deletions of GSTM1 in lung cancer patients from north Sichuan of China is slightly exceeding those of Europe and Americas (P <0.05) and similar to the domestic result (P >0.05).Conclusion The genetic polymorphism of GSTM1 to lung cancer patients in north Sichuan of China dosen' t show distinguished feature for this district and race.%目的 分析中国四川北部地区汉族肺癌人群谷胱苷肽硫转移酶M1(GSTM1)基因多态性.方法 采用聚合酶链反应(PCR)技术检测该地区125例肺癌患者GSTM1基因缺失频率,并与文献报道的其他地区人群及人种进行比较.结果 中国四川北部地区肺癌患者CSTM1纯合缺失基因型58.4%(73/125),其中纯和缺失率女性为62.5%(20/32),男性为56.9%(53/93);鳞状细胞癌56.1%(32/57),腺癌54.8%(17/31).与国内外文献报道比较,中国四川北部地区肺癌患者GSTM1基因缺失频率略高于欧美,但仅与土耳其、巴西非裔美国人和印度北部人群差异有统计学意义(P<0.05),与国内人群相近(P>0.05).结论 中国四川北部地区汉族肺癌人群GSTM1基因多态性未呈现显著的地域和人种特征.

  3. Interação entre consumo alimentar e polimorfismos da GSTM1 e GSTT1 no risco para o câncer de cabeça e pescoço: estudo caso-controle em São Paulo, Brasil Interaction between dietary intake and GSTM1 and GSTT1 polymorphisms in head and neck cancer risk: a case-control study in São Paulo, Brazil

    Directory of Open Access Journals (Sweden)

    Dirce Maria Lobo Marchioni

    2011-02-01

    Full Text Available O objetivo foi investigar a interação entre fatores dietéticos e polimorfismos de enzimas de metabolização de xenobióticos (GSTM1 e GSTT1 associadas ao câncer de cabeça e pescoço em um estudo caso controle de base hospitalar, no Município de São Paulo, Brasil. Participaram 103 casos incidentes, histologicamente confirmados, e 101 controles. O consumo alimentar foi obtido por um questionário de frequência alimentar validado. Os polimorfismos GSTM1 e GSTT1 foram avaliados pelo método PCR. Observou-se aumento de risco no mais alto tercil de consumo de carne bovina na presença do alelo nulo da GSTM1 (OR = 10,79; IC95%: 2,17-53,64 e GSTT1 (OR = 3,41; IC95%: 0,43-27,21. Considerando-se a razão entre alimentos de origem animal e vegetal, verificou-se para o tercil intermediário a OR = 2,02 (IC95%: 0,24-16,0 e no tercil superior OR = 3,23 (IC95%: 0,40-25,92. Os resultados apontam para uma possível interação entre o consumo de carne e variantes polimórficas dos genes GSTM1 e GSTT1 na modulação do risco para o câncer de cabeça e pescoço, influenciados pelo consumo de alimentos de origem vegetal.A hospital-based case-control study was conducted to investigate the potential interaction between dietary factors and polymorphisms in phase II metabolic enzymes GSTM1 and GSTT1, associated with head and neck cancer risk. The study included 103 histologically confirmed incident cases and 101 controls. Food intake was estimated with a validated food frequency questionnaire. The gene polymorphisms were evaluated by PCR. Increased risk was observed in the highest tertile of beef consumption in the presence of the GSTM1 (OR = 10.79; 95%CI: 2.17-53.64 and GSTT1 null alleles (OR = 3.41; 95%CI: 0.43-27.21. Assessment of dietary intake considering the ratio between animal product and vegetable consumption showed OR = 2.35 (95%CI: 0.27-19.85 in the intermediate tertile and OR = 3.36 (95%CI: 0.41-27.03 in the highest tertile. The results suggest a

  4. Genetic polymorphisms of the CYP1A1, GSTM1, and GSTT1 enzymes and their influence on cardiovascular risk and lipid profile in people who live near a natural gas plant.

    Science.gov (United States)

    Pašalić, Daria; Marinković, Natalija

    2017-03-01

    The aim of this cross-sectional study was to see whether genetic polymorphisms of the enzymes CYP1A1, GSTM1, and GSTT1 are associated with higher risk of coronary artery disease (CAD) and whether they affect lipid profile in 252 subjects living near a natural gas plant, who are likely to be exposed to polycyclic aromatic hydrocarbons (PAHs). Fasting serum concentrations of biochemical parameters were determined with standard methods. Genetic polymorphisms of CYP 1A1 rs4646903, rs1048943, rs4986883, and rs1799814 were genotyped with polymerase chain reaction-restriction fragment length polymorphism (PCR-RFPL), while GSTM1 and GSTT1 deletions were detected with multiplex PCR. Cardiovascular risk was assessed with Framingham risk score, and the subjects divided in two groups: >10% risk and ≤10% risk. The two groups did not differ in the genotype frequencies. MANCOVA analysis, which included lipid parameters, glucose, and BMI with sex, age, hypertension and smoking status as covariates, showed a significant difference between the GSTT1*0 and GSTT1*1 allele carriers (p=0.001). UNIANCOVA with same covariates showed that total cholesterol and triglyceride levels were significantly higher in GSTT1*1 allele carriers than in GSTT1*0 carriers (p<0.001 and p=0.006, respectively). Our findings suggest that CYP1A1, GSTM1, and GSTT1 polymorphisms are not associated with the higher risk of CAD, but that GSTT1 affects lipid profile.

  5. Multiplex PCR detection of GSTM1, GSTT1, and GSTP1 gene variants: simultaneously detecting GSTM1 and GSTT1 gene copy number and the allelic status of the GSTP1 Ile105Val genetic variant

    DEFF Research Database (Denmark)

    Buchard, Anders; Sanchez Sanchez, Juan Jose; Dalhoff, Kim;

    2007-01-01

    The glutathione S-transferase (GST) genes GSTM1, GSTT1, and GSTP1 are involved in the detoxification of a broad range of toxic substances. Genetic polymorphisms in these genes have been studied intensively for their potential role in cancer susceptibility and drug response. In Caucasians, the enz...

  6. Cigarette smoking and colorectal cancer: APC mutations, hMLH1 Expression and GSTM1 and GSTT1 Polymorphisms

    NARCIS (Netherlands)

    Luchtenborg, M.; Weijenberg, M.P.; Kampman, E.; Muijen, van G.N.P.; Roemen, G.M.J.M.; Zeegers, M.; Goldbohm, R.A.; Veer, van 't P.; Goeij, de A.F.P.M.; Brandt, van den P.A.

    2005-01-01

    The contribution of cigarette smoking to sporadic colorectal cancer may differ according to molecular aspects of the tumor or according to glutathione S-transferase M1 (GSTM1) or glutathione S-transferase T1 (GSTT1) genotype. In the prospective Netherlands Cohort Study on Diet and Cancer, adjusted

  7. Cigarette smoking and colorectal cancer: APC mutations, hMLH1 expression, and GSTM1 and GSTT1 polymorphisms.

    NARCIS (Netherlands)

    Luchtenborg, M.; Weijenberg, M.P.; Kampman, E.; Muijen, G.N.P. van; Roemen, G.M.; Zeegers, M.P.; Goldbohm, R.A.; Veer, P. van 't; Goeij, A.F. de; Brandt, P.A. van den

    2005-01-01

    The contribution of cigarette smoking to sporadic colorectal cancer may differ according to molecular aspects of the tumor or according to glutathione S-transferase M1 (GSTM1) or glutathione S-transferase T1 (GSTT1) genotype. In the prospective Netherlands Cohort Study on Diet and Cancer, adjusted

  8. Frequency of glutathione-S-transferase null-M1 and null-T1 genotypes among the Turabah population in Saudi Arabia.

    Science.gov (United States)

    Mansour, A A; Saleh, O M; Askar, T; Salim, A M; Mergani, A

    2015-12-14

    Glutathione-S-transferases (GST) are key phase II detoxifying enzymes that play critical roles in protection against products of oxidative stress and against electrophiles. Glutathione S-transferase mu (GST-M1) and theta (GST-T1) are isoforms of glutathione transferase enzymes that participate in the metabolism of a wide range of chemicals. Deletion variants that are associated with a lack of enzyme function exist at both these loci. The frequencies of homozygous GSTM1 and GSTT1 deletion carriers are very high in most of the populations studied to date. The aim of this study was to investigate the frequencies of GSTM1 and GSTT1 genotypes among the Turabah population in Saudi Arabia in comparison with the data published for some other Arabic populations. The subjects consisted of 164 unrelated healthy individuals from the Turabah population. GST genotyping was performed by multiplex polymerase chain reaction-based methods. The GSTM1 deletion homozygosity was 56.1% and GSTT1 deletion homozygosity was 20.7%, while the GSTM1 and GSTT1 double-deletion homozygosity was 11.0%. Comparison with published data from Bahraini, Lebanese, and Tunisian populations demonstrated no significant difference for GSTM1 between these populations. The GSTT1 null-allele frequency was significantly lower than those for the Lebanese and Tunisian populations (P = 0.001) but similar to that for the Bahraini population (P = 0.099). Characterization of GST genetic polymorphisms in the Saudi population may aid in genetic studies on the association of GSTM1 and GSTT1 polymorphisms with disease risks and the pharmacogenetics of chemotherapy.

  9. The frequency of GSTT1 null genotype in Turkish population and lung cancer risk

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    Demir A

    2005-01-01

    Full Text Available BACKGROUND : Previous studies have suggested that Glutathione S -transferase (GST genotypes may play a role in determining susceptibility to lung cancer, though the data are often conflicting. In different ethnic groups variations in null allele frequency has been observed. AIMS: We aimed to evaluate whether genetic polymorphisms of Glutathione S -transferase theta (GSTT1 influence individual susceptibility to lung cancer in Turkish population. We tried to clarify the frequencies of GSTM1 gene polymorphisms in a Turkish population. METHODS: DNA samples, extracted from the whole blood were amplified using polymerase chain reaction (PCR method in all of the 68 cases, composed of 31 previously diagnosed lung cancer and 37 healthy controls. RESULTS: The prevalence of GSTT1 null genotype in the lung cancer patients was 29%, compared to 11% in control group. GSTT1 null genotype was found to be higher in cancer group compared to the control group, although it was not statistically significant (OR = 3.37, 95% CI = 0.92-12.32, P = 0.06. There was also no significant relation in GSTT1 genotypes among histopathology types of lung cancers. The frequency of GSTT1 was found to be 25.4% ( n = 952 when the studies of Turkish population were reviewed. CONCLUSION: It can be concluded that carrying the GSTT1 null genotype may be accepted as a weak risk factor for the susceptibility to lung cancer.

  10. Interaction between gas cooking and GSTM1 null genotype in bronchial responsiveness: results from the European Community Respiratory Health Survey.

    NARCIS (Netherlands)

    Amaral, A.F.S.; Ramasamy, A.; Castro-Giner, F.; Minelli, C.; Accordini, S.; Sorheim, I.C.; Pin, I.; Kogevinas, M.; Jögi, R.; Balding, D.J.; Norbäck, D.; Verlato, G.; Olivieri, M.; Probst-Hensch, N.; Janson, C.; Zock, J.P.; Heinrich, J.; Jarvis, D.L.

    2014-01-01

    Background: Increased bronchial responsiveness is characteristic of asthma. Gas cooking, which is a major indoor source of the highly oxidant nitrogen dioxide, has been associated with respiratory symptoms and reduced lung function. However, little is known about the effect of gas cooking on bronchi

  11. Cardiovascular Effects Caused by Increasing Concentrations of Diesel Exhaust in Middle-Aged Healthy GSTM1 Null Human Volunteers

    Science.gov (United States)

    ABSTRACT Objectives: Epidemiological studies have shown an association between the incidence of adverse cardiovascular effects and exposure to ambient particulate matter (PM). Diesel exhaust (DE) is a major contributor to ambient PM in urban areas. This study was designed to e...

  12. The interaction of glutathione S-transferase M1-null variants with tobacco smoke exposure and the development of childhood asthma

    DEFF Research Database (Denmark)

    Rogers, A J; Brasch-Andersen, C; Ionita-Laza, I;

    2009-01-01

    : To explore the joint interactive effects of GSTM1 copy number and tobacco smoke exposure on the development of asthma and asthma-related phenotypes in a family-based cohort of childhood asthmatics. METHODS: We performed quantitative PCR-based genotyping for GSTM1 copy number in children of self......BACKGROUND: The glutathione S-transferase M1 (GSTM1)-null variant is a common copy number variant associated with adverse pulmonary outcomes, including asthma and airflow obstruction, with evidence of important gene-by-environment interactions with exposures to oxidative stress. OBJECTIVE......-reported white ancestry with mild to moderate asthma in the Childhood Asthma Management Program. Questionnaire data regarding intrauterine (IUS) and post-natal, longitudinal smoke exposure were available. We performed both family-based and population-based tests of association for the interaction between GSTM1...

  13. Management Features of Asthma in Children Under the Deletion Polymorphism of Genes Gstt1 and Gstm1

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    Elena C. Koloskova

    2015-03-01

    Full Text Available It has been performed complex examination of 50 school-aged children with bronchial asthma, which included a study of acetylation phenotype and a determination of deletions in the genes of glutathione-S-transferase (GSTM1 and GSTT1. The study has shown that in children with slow acetylation phenotype and the absence of deletions in genes GSTT1 and GSTM1 аssociates with poor control of the disease that requires increased anti-inflammatory therapy with an emphasis on higher "step". When using the ACT test for the assessment of asthma control often determined by the underestimation of their child's condition, indicating that about the need for the objectification of control of the disease with the help of spirographic method and subsequent correction of the basic therapy.

  14. Influence of GSTM1, GSTT1, GSTP1, NAT1, NAT2, EPHX1, MTR and MTHFR polymorphism on chromosomal aberration frequencies in human lymphocytes.

    Science.gov (United States)

    Skjelbred, Camilla Furu; Svendsen, Marit; Haugan, Vera; Eek, Anette Kildal; Clausen, Kjell Oskar; Kure, Elin H; Tuimala, Jarno T; Svendsen, Martin Veel; Norppa, Hannu; Hansteen, Inger-Lise

    2011-03-01

    We have studied the influence of genetic polymorphisms in the xenobiotic-metabolizing genes GSTM1, GSTP1, GSTT1, EPHX1, NAT1 and NAT2 and the folate-metabolizing genes MTR and MTHFR on the frequencies of cells with chromosomal aberrations (CAs) in peripheral lymphocytes of Norwegian men. Log-linear Poisson regression models were applied on 357 subjects of whom data on all the polymorphisms examined were available. Total CAs and chromosome-type aberrations (CSAs) were significantly increased by higher age alone, whereas chromatid-type aberrations (CTAs) were elevated by the GSTT1-null genotype and MTHFR codon 222 variant allele and chromatid gaps (CTGs) by EPHX1 high activity genotype and occupational exposure. Stratification by smoking and age (<40 and ≥40 years) showed that the effect of the GSTT1 null and EPHX1 high activity genotypes only concerned (older) smokers, in agreement with the roles of the respective enzymes in detoxification and metabolic activation. The MTHFR codon 222 variant allele was associated with high CTGs in smokers, the MTR codon 919 variant allele with high CTAs in older smokers and the NAT2 fast acetylator genotype with high CTGs in older subjects. Among younger nonsmokers, however, carriers of the MTHFR codon 222 and MTR codon 919 variant alleles showed a decrease in the level of CTGs and total CAs, respectively. In conclusion, polymorphisms of GSTT1, EPHX1, MTHFR, MTR and NAT2 differentially affect the frequency of CTAs, CSAs and CTGs, showing interaction with smoking and age. It appears that CA subtypes rather than total CAs should be considered in this type of studies.

  15. Susceptibility to urinary bladder cancer: relevance of rs9642880[T], GSTM1 0/0 and occupational exposure.

    Science.gov (United States)

    Golka, Klaus; Hermes, Matthias; Selinski, Silvia; Blaszkewicz, Meinolf; Bolt, Hermann M; Roth, Gerhard; Dietrich, Holger; Prager, Hans-Martin; Ickstadt, Katja; Hengstler, Jan G

    2009-11-01

    Recently, a genome-wide single nucleotide polymorphism association study has identified a sequence variant 30 kb upstream of the c-Myc gene (allele T of rs9642880) that confers susceptibility to bladder cancer. However, the role of exposure to bladder carcinogens has not been considered. This prompted us to analyse the relevance of this polymorphism in 515 bladder cancer cases and 893 controls where the quality and quantity of occupational exposure to bladder carcinogens has been documented. When we analysed a hospital-based case-control series not selected for occupational exposure, rs9642880[T] was influential, in contrast to GSTM1 0/0. However, in a case-control series of patients that have been occupationally exposed to aromatic amines and polycyclic aromatic hydrocarbons, rs9642880[T] was not influential but GSTM1 0/0 was significantly associated with bladder cancer risk. Therefore, the degree to which rs9642880[T] and GSTM1 0/0 confer susceptibility to urinary bladder cancer seems to depend on the extent of exposure to urinary bladder carcinogens.

  16. Analysis of case-parent trios at a locus with a deletion allele: association of GSTM1 with autism

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    Wang Rong

    2006-02-01

    Full Text Available Abstract Background Certain loci on the human genome, such as glutathione S-transferase M1 (GSTM1, do not permit heterozygotes to be reliably determined by commonly used methods. Association of such a locus with a disease is therefore generally tested with a case-control design. When subjects have already been ascertained in a case-parent design however, the question arises as to whether the data can still be used to test disease association at such a locus. Results A likelihood ratio test was constructed that can be used with a case-parents design but has somewhat less power than a Pearson's chi-squared test that uses a case-control design. The test is illustrated on a novel dataset showing a genotype relative risk near 2 for the homozygous GSTM1 deletion genotype and autism. Conclusion Although the case-control design will remain the mainstay for a locus with a deletion, the likelihood ratio test will be useful for such a locus analyzed as part of a larger case-parent study design. The likelihood ratio test has the advantage that it can incorporate complete and incomplete case-parent trios as well as independent cases and controls. Both analyses support (p = 0.046 for the proposed test, p = 0.028 for the case-control analysis an association of the homozygous GSTM1 deletion genotype with autism.

  17. Analysis of case-parent trios at a locus with a deletion allele: association of GSTM1 with autism.

    Science.gov (United States)

    Buyske, Steven; Williams, Tanishia A; Mars, Audrey E; Stenroos, Edward S; Ming, Sue X; Wang, Rong; Sreenath, Madhura; Factura, Marivic F; Reddy, Chitra; Lambert, George H; Johnson, William G

    2006-02-10

    Certain loci on the human genome, such as glutathione S-transferase M1 (GSTM1), do not permit heterozygotes to be reliably determined by commonly used methods. Association of such a locus with a disease is therefore generally tested with a case-control design. When subjects have already been ascertained in a case-parent design however, the question arises as to whether the data can still be used to test disease association at such a locus. A likelihood ratio test was constructed that can be used with a case-parents design but has somewhat less power than a Pearson's chi-squared test that uses a case-control design. The test is illustrated on a novel dataset showing a genotype relative risk near 2 for the homozygous GSTM1 deletion genotype and autism. Although the case-control design will remain the mainstay for a locus with a deletion, the likelihood ratio test will be useful for such a locus analyzed as part of a larger case-parent study design. The likelihood ratio test has the advantage that it can incorporate complete and incomplete case-parent trios as well as independent cases and controls. Both analyses support (p = 0.046 for the proposed test, p = 0.028 for the case-control analysis) an association of the homozygous GSTM1 deletion genotype with autism.

  18. Effect of GSTM1, GSTT1, and GSTP1 IIe105Val polymorphisms on susceptiblity to gestational diabetes mellitus.

    Science.gov (United States)

    Qiu, Y H; Xu, Y L; Zhang, W H

    2016-06-03

    We investigate the role of the GSTM1, GSTT1, and GSTP1 IIe105Val genetic polymorphisms in the susceptibility to gestational diabetes mellitus. A total of 223 pregnant women with gestational diabetes mellitus and 265 healthy pregnant women were examined at The Second Affiliated Hospital of Shaanxi University of Chinese Medicine from May 2013 to November 2013. Genotyping for detection of GSTM1, GSTT1, and GSTP1 IIe105Val polymorphisms was conducted using the restriction fragment length polymorphism-polymerase chain reaction. There were statistically significant differences between patients with gestational diabetes mellitus and control subjects in terms of age (χ(2) = 6.68, P = 0.01) and BMI (t = 7.56, P gestational diabetes mellitus compared to the present genotype [adjusted OR (95%CI) = 1.85 (1.26-2.72)]. However, the unconditional logistic analysis revealed that GSTT1 and GSTP1 IIe105Val polymorphisms could not influence the risk of gestational diabetes mellitus in a Chinese population. In summary, we suggest that the GSTM1 gene polymorphism could influence the susceptibility to gestational diabetes mellitus in a Chinese population.

  19. Role of GSTM1 Copy Number Variant in the Prognosis of Thai Colorectal Cancer Patients Treated with 5-FU-based Chemotherapy

    Science.gov (United States)

    Pongtheerat, Tanett; Saelee, Pensri

    2016-10-01

    Background: Glutathione S-transferase M1 (GSTM1) is involved in the detoxification of carcinogenic agents. DNA copy number variants of GSTM1 may be associated with cancer progression and may result in reduced survival time of various cancers. Determination of DNA copy number variants was here used to assess the association between GSTM1 copy number variant and pathological status and survival time of colorectal-cancer patients treated with 5-fluorouracil-based chemotherapy. Methods: One hundred thirteen Thai colorectal-cancer patients were investigated for GSTM1 copy number variant by real-time PCR. Relationships between gene copy number variants and clinico-pathological parameters were determined. Result: Associations were evident between GSTM1 copy number and stage of tumor (P = 0.026) and metastasis at diagnosis (P = 0.049), with odds ratio values of 0.2 and 0.3 respectively. Conclusions: GSTM1 copy number variant was here not related with reduced overall survival for the colorectal-cancer patients receiving 5-FU-based chemotherapy. Creative Commons Attribution License

  20. Características mamográficas do câncer de mama associadas aos polimorfismos GSTM1 e GSTT1 Polymorphisms GSTM1 and GSTT1 and sporadic breast cancer mammographic features

    Directory of Open Access Journals (Sweden)

    Lívia Martins Tavares Scianni Morais

    2008-02-01

    Full Text Available INTRODUÇÃO: As enzimas do sistema da glutationa S-transferase (GST modulam os efeitos da exposição a vários agentes citotóxicos e genotóxicos. Os genes GSTM1 e GSTT1 são polimórficos em humanos e suas deleções têm sido associadas ao aumento do risco de várias neoplasias, dentre elas o câncer de mama. OBJETIVO: Comparar a freqüência das deleções dos genes GSTM1 e GSTT1 em mulheres sadias e com câncer de mama e comparar as características mamográficas do câncer entre mulheres portadoras e não portadoras das referidas deleções. MÉTODOS: Foram determinadas as freqüências das referidas deleções por PCR em 100 pacientes portadoras de câncer de mama esporádico tratadas de setembro de 2004 a junho de 2005 e em 169 mulheres sadias doadoras de sangue no mesmo período e comparadas através do odds ratio (OR com seus respectivos IC 95%. Foram revistos os prontuários e as mamografias das pacientes com câncer e avaliadas características mamográficas (padrão de distribuição do parênquima fibro-glandular, achados mamográficos ao diagnóstico e classificação BI-RADS, correlacionando-as às deleções gênicas através do cálculo da RP (razão de prevalência com seus respectivos IC 95%. RESULTADOS: O GSTM1 esteve deletado em 40% dos cânceres e em 44,4% dos controles (OR=1,20; IC 95% 0,70-2,04; p=0,5659 enquanto o GSTT1 em 20% e 19,5%, respectivamente (OR=0,73; IC 0,37-1,44; p=0,4124. O padrão mamográfico denso esteve associado à deleção homozigótica do GSTM1 (RP= 2,43; IC 1,11-4,08. Não se observou associação entre as deleções do sistema GST e achados mamográficos ao diagnóstico e classificação BI-RADS. CONCLUSÃO: A deleção homozigótica do gene GSTM1 associou-se ao padrão mamográfico denso.INTRODUCTION: Enzymes of the Glutathione S-transferase system (GST modulate the effects of exposure to several cytotoxic and genotoxic agents. The GSTM1 and GSTT1 genes are polymorphic in humans and their

  1. Can GSTM1 and GSTT1 polymorphisms predict clinical outcomes of chemotherapy in gastric and colorectal cancers? A result based on the previous reports

    Directory of Open Access Journals (Sweden)

    Liu H

    2016-06-01

    Full Text Available Haixia Liu,1,* Wei Shi,2,* Lianli Zhao,3 Dianlu Dai,4 Jinghua Gao,5 Xiangjun Kong6 1Department of Ultrasound, 2Office of Medical Statistics, 3Human Resource Department, 4Department of Surgical Oncology, 5Department of Medical Oncology, 6Central Laboratory, Cangzhou Central Hospital, Yunhe District, Cangzhou, People’s Republic of China *These authors contributed equally to this study and should be considered cofirst authors Background: Gastric and colorectal cancers remain the major causes of cancer-related death. Although chemotherapy improves the prognosis of the patients with gastrointestinal cancers, some patients do not benefit from therapy and are exposed to the adverse effects. The polymorphisms in genes including GSTM1 and GSTT1 have been explored to predict therapeutic efficacy; however, the results were inconsistent and inconclusive. Materials and methods: A systematic review and meta-analysis was performed by searching relevant studies about the association between the GSTM1 and GSTT1 polymorphisms and chemotherapy efficacy in gastrointestinal cancers in databases such as PubMed, EMBASE, Web of Science, Chinese National Knowledge Infrastructure, and Wanfang database up to January 10, 2016. Subgroup analyses were also performed according to ethnicity, cancer type, evaluation criteria, study type, chemotherapy type, and age. Results: A total of 19 articles containing 3,217 cases were finally included. Overall analysis suggested that no significance was found between overall toxicity, neurotoxicity, neutropenia, gastrointestinal toxicity, tumor response, and progression-free survival, and the polymorphisms in GSTM1 and GSTT1, while GSTM1 polymorphism associated with overall survival (OS; hazard ratio =1.213, 95% confidence interval =1.060–1.388, P=0.005. Subgroup analyses suggested that neurotoxicity was associated with GSTM1 polymorphism in the Asian population, neutropenia was associated with GSTM1 polymorphism in palliative

  2. Homozygosity for a null allele of SMIM1 defines the Vel-negative blood group phenotype.

    Science.gov (United States)

    Storry, Jill R; Jöud, Magnus; Christophersen, Mikael Kronborg; Thuresson, Britt; Åkerström, Bo; Sojka, Birgitta Nilsson; Nilsson, Björn; Olsson, Martin L

    2013-05-01

    The Vel antigen is present on red blood cells (RBCs) from all humans except rare Vel-negative individuals who can form antibodies to Vel in response to transfusion or pregnancy. These antibodies may cause severe hemolytic reactions in blood recipients. We combined SNP profiling and transcriptional network modeling to link the Vel-negative phenotype to SMIM1, located in a 97-kb haplotype block on chromosome 1p36. This gene encodes a previously undiscovered, evolutionarily conserved transmembrane protein expressed on RBCs. Notably, 35 of 35 Vel-negative individuals were homozygous for a frameshift deletion of 17 bp in exon 3. Functional studies using antibodies raised against SMIM1 peptides confirmed a null phenotype in RBC membranes, and SMIM1 overexpression induced Vel expression. Genotype screening estimated that ~1 of 17 Swedish blood donors is a heterozygous deletion carrier and ~1 of 1,200 is a homozygous deletion knockout and enabled identification of Vel-negative donors. Our results establish SMIM1 as a new erythroid gene and Vel as a new blood group system.

  3. GSTM1 modulation of IL-8 expression in human epithelial cells exposed to ozone

    Science.gov (United States)

    Exposure to the major air pollutant ozone can aggravate asthma and other lung diseases. Our recent study in humanvolunteers hasshown that the glutathione S-transferase Mu 1(GSTMI)-null genotype is associated with increased airway neutrophilic inflammation induced by inhaled ozone...

  4. Females with paired occurrence of cancers in the UADT and genital region have a higher frequency of either Glutathione S-transferase M1/T1 null genotype

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    Jhavar Sameer G

    2005-03-01

    Full Text Available Abstract Upper Aero digestive Tract (UADT is the commonest site for the development of second cancer in females after primary cervical cancer. Glutathione S-transferase (GSTM1 and / or T1 null genotype modulates the risk of developing UADT cancer (primary as well as second cancer. The aim of this study was to evaluate the difference in GST null genotype frequencies in females with paired cancers in the UADT and genital region as compared to females with paired cancers in the UADT and non-genital region. Forty-nine females with a cancer in the UADT and another cancer (at all sites-genital and non-genital were identified from a database of patients with multiple primary neoplasms and were analyzed for the GSTM1 and T1 genotype in addition to known factors such as age, tobacco habits, alcohol habits and family history of cancer. Frequencies of GSTM1 null, GSTT1 null, and either GSTM1/T1 null were higher in females with paired occurrence of cancer in the UADT and genital site (54%, 33% and 75% respectively in comparison to females with paired occurrence of cancer in the UADT and non-genital sites (22%, 6% and 24% respectively. The significantly higher inherited frequency of either GSTM1/T1 null genotype in females with a paired occurrence of cancers in UADT and genital region (p = 0.01, suggests that these females are more susceptible to damage by carcinogens as compared to females who have UADT cancers in association with cancers at non-genital sites.

  5. Association of polymorphisms in AhR, CYP1A1, GSTM1, and GSTT1 genes with levels of DNA damage in peripheral blood lymphocytes among coke-oven workers

    Energy Technology Data Exchange (ETDEWEB)

    Yongwen Chen; Yun Bai; Jing Yuan; Weihong Chen; Jianya Sun; Hong Wang; Huashan Liang; Liang Guo; Xiaobo Yang; Hao Tan; Yougong Su; Qingyi Wei; Tangchun Wu [Huazhong University of Science and Technology, Wuhan (China). Institute of Occupational Medicine and Ministry of Education Key Lab of Environment and Health

    2006-09-15

    Accumulating evidence has shown that both DNA damage caused by the metabolites of polycyclic aromatic hydrocarbons (PAH) and genetic polymorphisms in PAH-metabolic genes contribute to individual susceptibility to PAH-induced carcinogenesis. However, the functional relevance of genetic polymorphisms in PAH-metabolic genes in exposed individuals is still unclear. In this study of 240 coke-oven workers (the exposed group) and 123 non-coke-oven workers (the control group), we genotyped for polymorphisms in the AhR, CYP1A1, GSTM1, and GSTT1 genes by PCR methods, and determined the levels of DNA damage in peripheral blood lymphocytes using the alkaline comet assay. It was found that the ln-transformed Olive tail moment (Olive TM) values in the exposed group were significantly higher than those in the control group. Furthermore, in the exposed group, the Olive TM values in subjects with the AhR Lys{sup 554} variant genotype were higher than those with the AhR Arg{sup 554}/Arg{sup 554} genotype. Similarly, the Olive TM values in the non-coke-oven workers with the CYP1A1 MspI CC + CT genotype were lower than the values of those with the CYP1A1 MspI TT genotype. However, these differences were not evident for GSTM1 and GSTT1. These results suggested that the polymorphism of AhR might modulate the effects of PAHs in the exposed group; however, the underlying molecular mechanisms by which this polymorphism may have affected the levels of PAH-induced DNA damage warrant further investigation.

  6. Genetic Polymorphisms of Glutathione-Related Enzymes (GSTM1, GSTT1, and GSTP1 and Schizophrenia Risk: A Meta-Analysis

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    Su Kang Kim

    2015-08-01

    Full Text Available The association between polymorphisms of glutathione-related enzyme (GST genes and the risk of schizophrenia has been investigated in many published studies. However, their results were inconclusive. Therefore, we performed a meta-analysis to explore the association between the GSTM1, GSTT1, and GSTP1 polymorphisms and the risk of schizophrenia. Twelve case-control studies were included in this meta-analysis. The odds ratio (OR and 95% confidence interval (95% CI were used to investigate the strength of the association. Our meta-analysis results revealed that GSTM1, GSTT1, and GSTP1 polymorphisms were not related to risk of schizophrenia (p > 0.05 in each model. Further analyses based on ethnicity, GSTM polymorphism showed weak association with schizophrenia in East Asian population (OR = 1.314, 95% CI = 1.025–1.684, p = 0.031. In conclusion, our meta-analysis indicated the GSTM1 polymorphism may be the only genetic risk factor for schizophrenia in East Asian population. However, more meta-analysis with a larger sample size were needed to provide more precise evidence.

  7. Genome-wide CNV analysis replicates the association between GSTM1 deletion and bladder cancer: a support for using continuous measurement from SNP-array data

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    Marenne Gaëlle

    2012-07-01

    Full Text Available Abstract Background Structural variations such as copy number variants (CNV influence the expression of different phenotypic traits. Algorithms to identify CNVs through SNP-array platforms are available. The ability to evaluate well-characterized CNVs such as GSTM1 (1p13.3 deletion provides an important opportunity to assess their performance. Results 773 cases and 759 controls from the SBC/EPICURO Study were genotyped in the GSTM1 region using TaqMan, Multiplex Ligation-dependent Probe Amplification (MLPA, and Illumina Infinium 1 M SNP-array platforms. CNV callings provided by TaqMan and MLPA were highly concordant and replicated the association between GSTM1 and bladder cancer. This was not the case when CNVs were called using Illumina 1 M data through available algorithms since no deletion was detected across the study samples. In contrast, when the Log R Ratio (LRR was used as a continuous measure for the 5 probes contained in this locus, we were able to detect their association with bladder cancer using simple regression models or more sophisticated methods such as the ones implemented in the CNVtools package. Conclusions This study highlights an important limitation in the CNV calling from SNP-array data in regions of common aberrations and suggests that there may be added advantage for using LRR as a continuous measure in association tests rather than relying on calling algorithms.

  8. Enhanced glutathione depletion, protein adduct formation, and cytotoxicity following exposure to 4-hydroxy-2-nonenal (HNE) in cells expressing human multidrug resistance protein-1 (MRP1) together with human glutathione S-transferase-M1 (GSTM1).

    Science.gov (United States)

    Rudd, Lisa P; Kabler, Sandra L; Morrow, Charles S; Townsend, Alan J

    2011-11-15

    4-Hydroxy-2-nonenal (HNE) is one of the most reactive products of lipid peroxidation and has both cytotoxic and genotoxic effects in cells. Several enzymatic pathways have been reported to detoxify HNE, including conjugation by glutathione-S-transferases (GSTs). Removal of the resulting HNE-glutathione conjugate (HNE-SG) by an efflux transporter may be required for complete detoxification. We investigated the effect of expression of GSTM1 and/or the ABC efflux transporter protein, multidrug-resistance protein-1 (MRP1), on HNE-induced cellular toxicity. Stably transfected MCF7 cell lines were used to examine the effect of GSTM1 and/or MRP1 expression on HNE-induced cytotoxicity, GSH depletion, and HNE-protein adduct formation. Co-expression in the MCF7 cell line of GSTM1 with MRP1 resulted in a 2.3-fold sensitization to HNE cytotoxicity (0.44-fold IC(50) value relative to control) rather than the expected protection. Expression of either GSTM1 or MRP1 alone also resulted in slight sensitization to HNE cytotoxicity (0.79-fold and 0.71-fold decreases in IC(50) values, respectively). Co-expression of GSTM1 and MRP1 strongly enhanced the formation of HNE-protein adducts relative to the non-expressing control cell line, whereas expression of either MRP1 alone or GSTM1 alone yielded similarly low levels of HNE-protein adducts to that of the control cell line. Glutathione (GSH) levels were reduced by 10-20% in either the control cell line or the MCF7/GSTM1 cell line with the same HNE exposure for 60min. However, HNE induced >80% depletion of GSH in cells expressing MRP1 alone. Co-expression of both MRP1 and GSTM1 caused slightly greater GSH depletion, consistent with the greater protein adduct formation and cytotoxicity in this cell line. Since expression of GSTM1 or MRP1 alone did not strongly sensitize cells to HNE, or result in greater HNE-protein adducts than in the control cell line, these results indicate that MRP1 and GSTM1 collaborate to enhance HNE-protein adduct

  9. Effects of APOE rs429358, rs7412 and GSTM1/GSTT1 Polymorphism on Plasma and Erythrocyte Antioxidant Parameters and Cognition in Old Chinese Adults

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    Linhong Yuan

    2015-09-01

    Full Text Available Apolipoprotein E (APOE and oxidative damage were correlated with the risk of Alzheimer’s disease (AD. Glutathione S-transferase (GST polymorphism was proved to be associated with body antioxidant capacity and involved in the oxidative damage related chronic diseases. To explore the combined effects of APOE rs429358, rs7412 and GSTM1/T1 polymorphism on antioxidant parameters and cognition in old Chinese adults, a community-based cross-sectional study was carried out in 477 Chinese adults aged from 55 to 75. Information on demography and lifestyle of the participants was collected with a questionnaire. Cognitive function was measured by using a Montreal Cognitive Assessment (MoCA test. Fasting venous blood samples were collected for APOE rs429358, rs7412 and GSTM1/T1 genotyping, and parameter measurement. No association of APOE rs7412, rs429358 and GSTM1/T1 polymorphisms with cognition was detected in the old Chinese adults. APOE rs429358, rs7412 polymorphism was mainly associated with plasma α-tocopherol, low density lipoprotein cholesterol (LDL-C and plasma total antioxidant capacity (T-AOC levels (p < 0.05. Interaction of APOE rs429358 and GSTT1 genotype on the plasma triglyceride (TG level and erythrocyte catalase (CAT and GST enzyme activities were detected (p < 0.05. The subjects with APOE rs429358 T/C + C/C and GSTT1− genotype were found to have the highest plasma TG level, erythrocyte CAT enzyme activity, and the lowest GST enzyme activity compared to subjects with other genotypes (p < 0.05. Lowest erythrocyte CAT enzyme activity and highest glutathione peroxidase (GSH-Px enzyme activity were detected in the subjects with APOE rs7412 T/C + T/T and GSTM1+ genotype as compared with subjects with other genotypes. The levels of plasma and erythrocyte antioxidant parameters were APOE genotype associated. GSTM1 or GSTT1 genotype modified the influence of APOE rs7412, rs429358 polymorphism on antioxidant parameters.

  10. The effect of cigarette smoke and arsenic exposure on urothelial carcinoma risk is modified by glutathione S-transferase M1 gene null genotype

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Chi-Jung [Department of Health Risk Management, College of Public Health, China Medical University, Taichung, Taiwan (China); Department of Medical Research, China Medical University Hospital, Taichung, Taiwan (China); Huang, Chao-Yuan; Pu, Yeong-Shiau [Department of Urology, National Taiwan University Hospital, Taipei, Taiwan (China); Shiue, Horng-Sheng [Department of Chinese Medicine, Chang Gung Memorial Hospital, Taipei, Taiwan (China); Su, Chien-Tien [Department of Family Medicine, Taipei Medical University Hospital, Taipei, Taiwan (China); Hsueh, Yu-Mei, E-mail: ymhsueh@tmu.edu.tw [Department of Public Health, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan (China); School of Public Health, College of Public Health and Nutrition, Taipei Medical University, Taipei, Taiwan (China)

    2013-01-15

    Inter-individual variation in the metabolism of xenobiotics, caused by factors such as cigarette smoking or inorganic arsenic exposure, is hypothesized to be a susceptibility factor for urothelial carcinoma (UC). Therefore, our study aimed to evaluate the role of gene–environment interaction in the carcinogenesis of UC. A hospital-based case–control study was conducted. Urinary arsenic profiles were measured using high-performance liquid chromatography–hydride generator-atomic absorption spectrometry. Genotyping was performed using a polymerase chain reaction-restriction fragment length polymorphism technique. Information about cigarette smoking exposure was acquired from a lifestyle questionnaire. Multivariate logistic regression was applied to estimate the UC risk associated with certain risk factors. We found that UC patients had higher urinary levels of total arsenic, higher percentages of inorganic arsenic (InAs%) and monomethylarsonic acid (MMA%) and lower percentages of dimethylarsinic acid (DMA%) compared to controls. Subjects carrying the GSTM1 null genotype had significantly increased UC risk. However, no association was observed between gene polymorphisms of CYP1A1, EPHX1, SULT1A1 and GSTT1 and UC risk after adjustment for age and sex. Significant gene–environment interactions among urinary arsenic profile, cigarette smoking, and GSTM1 wild/null polymorphism and UC risk were observed after adjustment for potential risk factors. Overall, gene–environment interactions simultaneously played an important role in UC carcinogenesis. In the future, large-scale studies should be conducted using tag-SNPs of xenobiotic-metabolism-related enzymes for gene determination. -- Highlights: ► Subjects with GSTM1 null genotype had significantly increased UC risk. ► UC patients had poor arsenic metabolic ability compared to controls. ► GSTM1 null genotype may modify arsenic related UC risk.

  11. Relationship between GSTT1, GSTM1, NQO1, RAD51 and XRCC3 genes polymorphisms and chronic myeloid leukemia%GSTT1、GSTM1、NQO1、RAD51和XRCC3基因多态性与慢性粒细胞白血病发生关系的研究

    Institute of Scientific and Technical Information of China (English)

    杨琳; 徐世才; 刘旭平; 张美荣; 张悦; 肖志坚

    2006-01-01

    目的探讨GSTT1、GSTM1、NQO1、RAD51和XRCC3基因多态性与我国慢性粒细胞白血病(CML)发生遗传易感之间的关系.方法共120例CML患者和458名与患者无血缘关系的正常人,用多重PCR方法检测GSTT1和GSTM1基因型,用PCR-RFLP方法分析RAD51,XRCC3,NQO1基因型.结果CML患者GSTT1和GSTM1缺失型比例分别为50.8%和59.2%,与正常对照组无显著差异(分别为42.8%和53.1%).CML患者NQO1 C/T和T/T基因型的比例(60.0%)、RAD51 G135CG/C基因型比例(26.9%)和XRCC3-241Met杂合子缺失型(Thr/Met)的比例(9.2%)均与正常对照组(分别为65.3%,12.4%和9.2%)无统计学差异.结论本研究结果提示GSTT1、GSTM1、NQO1、RAD51和XRCC3基因型与我国CML的发生无显著相关性.

  12. Null surfaces of null curves on 3-null cone

    Science.gov (United States)

    Sun, Jianguo; Pei, Donghe

    2014-03-01

    The null surfaces of null curves on 3-null cone have the applications in the studying of horizon types. Via the pseudo-scalar product and Frenet equations, the differential geometry of null curves on 3-null cone is obtained. In the local sense, the curvature describes the contact of submanifolds with pseudo-spheres. We introduce the geometric properties of the curvatures and show the singularities of null surfaces, which are constructed over the null curves.

  13. Genetic polymorphisms of GSTM1, GSTT1 and GSTP1 and susceptibility to DNA damage in workers occupationally exposed to organophosphate pesticides.

    Science.gov (United States)

    Singh, Satyender; Kumar, Vivek; Singh, Priyanka; Thakur, Sachin; Banerjee, Basu Dev; Rautela, Rajender Singh; Grover, Shyam Sunder; Rawat, Devendra Singh; Pasha, Syed Tazeen; Jain, Sudhir Kumar; Rai, Arvind

    2011-10-09

    GSTM1, T1 and P1 are important enzymes of glutathione S-transferases (GSTs), involved in the metabolism of many endogenous and exogenous compounds. Individual genetic variation in these metabolizing enzymes may influence the metabolism of their substrates. The present study was designed to determine the genotoxic effects using DNA damage and its association with GSTM1, GSTT1, and GSTP1 (Ile105Val) genetic polymorphisms in workers occupationally exposed to organophosphate pesticides (OPs). We examined 230 subjects including 115 workers occupationally exposed to OPs and an equal number of normal healthy controls. The DNA damage was evaluated using the alkaline comet assay and genotyping was done using individual PCR or PCR-RFLP. Significantly higher DNA tail moment (TM) was observed in workers as compared to control subjects (14.41 ± 2.25 vs. 6.36 ± 1.41 tail % DNA, pdamage arises from the gene-environment interactions in workers occupationally exposed to OPs. 2011 Elsevier B.V. All rights reserved.

  14. CYP2D6, GST-M1 and GST-T1 enzymes: expression in parathyroid gland and association with the parathyroid hormone concentration during early renal replacement therapy

    Science.gov (United States)

    Yan, Feng-Xiang; Langub, M Chris; Ihnen, Mark A; Hornung, Carlton; Juronen, Erkki; Rayens, Mary K; Cai, Wei-Min; Wedlund, Peter J; Fanti, Paolo

    2003-01-01

    Aims The purpose of this research was to characterize CYP2D6, GST-M1 and GST-T1 enzyme expression in human parathyroid tissue, and to determine whether or not there is any association between deficiencies in these enzymes and serum parathyroid hormone concentrations in patients with end-stage renal disease. Methods Surgical human parathyroid tissue was obtained and evaluated by immunohistochemistry for cellular localization of CYP2D6, GST-M1 and GST-T1 and colocalization of CYP2D6 with parathyroid hormone. Blood samples were collected from 328 Caucasian patients with end-stage renal disease for genetic testing of CYP2D6*3, *4, *5, *6, *7 and GST-M1*0 and GST-T1*0 alleles. Clinical chemistry data and serum intact parathyroid hormone (iPTH) concentrations were obtained from patient medical records. In 277 of the patients, the same laboratory performed all clinical tests. Results CYP2D6, GST-M1 and GST-T1 were present in human parathyroid tissue. CYP2D6 was colocalized with parathyroid hormone in parathyroid chief cells. Within the end-stage renal disease population, a nonfunctional CYP2D6 genotype was present in 18.2%[95% confidence interval (CI) 8.0, 28.4] of patients in the 1st iPTH concentration quintile (iPTH 347 pg mL−1) (P = 0.001). Out of 12 CYP2D6-deficient females, seven were in the 1st iPTH concentration quintile and the remaining five were in the 5th quintile. Patients deficient in the GST-M1 and GST-T1 enzymes displayed a far more uniform frequency distribution relative to serum iPTH concentrations. Conclusions The presence of CYP2D6, GST-M1 and GST-T1 in parathyroid cells was observed. An association is reported between a lack of CYP2D6 and iPTH concentrations in newly diagnosed end-stage renal disease patients. Gender and concomitant deficiency in GST-M1 and/or GST-T1 appear to define this association further. It remains to be established whether these associations reflect a cause-effect relationship between deficient expression of metabolizing enzymes and severity of secondary manifestation of renal failure. PMID:12848777

  15. Point mutations and deletion responsible for the Bombay H null and the Reunion H weak blood groups.

    Science.gov (United States)

    Fernandez-Mateos, P; Cailleau, A; Henry, S; Costache, M; Elmgren, A; Svensson, L; Larson, G; Samuelsson, B E; Oriol, R; Mollicone, R

    1998-01-01

    Definition of the molecular basis of the Reunion and the Bombay red cell and salivary H-deficient phenotypes. Sequence and expression of FUT1 and FUT2 genes from H-deficient individuals. Family segregation analysis of the mutations responsible for the fucosyltransferase defects of H, secretor and Lewis systems. The Indian red cell H null Bombay phenotype depends on a new mutation of the FUT1 gene. T725-->G changing Leu242-->Arg. Their salivary nonsecretor phenotype is secondary to a complete deletion of the FUT2 gene. The red cell H weak Reunion phenotype depends on another new mutation of FUT1, C349-->T which induces a change of His117-->Tyr. Their salivary nonsecretor phenotype is due to the known Caucasian inactivating mutation G428-->A. Single prevalent FUT1 and FUT2 point mutations and a deletion are responsible for the Indian Bombay H null and the Reunion H weak phenotypes found on Reunion island. This is in contrast with other H-deficient phenotypes where sporadic nonprevalent inactivating mutations are the rule.

  16. Polymorphisms in CYP1B1, GSTM1, GSTT1 and GSTP1, and susceptibility to breast cancer.

    Science.gov (United States)

    Van Emburgh, Beth O; Hu, Jennifer J; Levine, Edward A; Mosley, Libyadda J; Perrier, Nancy D; Freimanis, Rita I; Allen, Glenn O; Rubin, Peter; Sherrill, Gary B; Shaw, Cindy S; Carey, Lisa A; Sawyer, Lynda R; Miller, Mark Steven

    2008-05-01

    Polymorphisms in the cytochrome P450 1B1 (CYP1B1) and glutathione S-transferase (GST) drug metabolic enzymes, which are responsible for metabolic activation/detoxification of estrogen and environmental carcinogens, were analyzed for their association with breast cancer risk in 541 cases and 635 controls from a North Carolina population. Each polymorphism, altering the catalytic function of their respective enzymes, was analyzed in Caucasian and African-American women. As reported in previous studies, individual polymorphisms did not significantly impact breast cancer risk in either Caucasian or African-American women. However, African-American women exhibited a trend towards a protective effect when they had at least one CYP1B1 119S allele (OR=0.53; 95% CI=0.20-1.40) and increased risk for those women harboring at least one CYP1B1 432V allele (OR=5.52; 95% CI=0.50-61.37). Stratified analyses demonstrated significant interactions in younger (age CYP1B1 119SS genotype (OR=3.09; 95% CI=1.22-7.84) and younger African-American women with the GSTT1 null genotype (OR=4.07; 95% CI=1.12-14.80). A notable trend was also found in Caucasian women with a history of smoking and at least one valine allele at GSTP1 114 (OR=2.12; 95% CI=1.02-4.41). In Caucasian women, the combined GSTP1 105IV/VV and CYP1B1 119AA genotypes resulted in a near 2-fold increase in risk (OR=1.96; 95% CI=1.04-3.72) and the three way combination of GSTP1 105IV/VV, CYP1B1 119AS/SS and GSTT1 null genotypes resulted in an almost 4-fold increase in risk (OR=3.97; 95% CI=1.27-12.40). These results suggest the importance of estrogen/carcinogen metabolic enzymes in the etiology of breast cancer, especially in women before the age of 60, as well as preventative measures such as smoking cessation.

  17. Null twisted geometries

    CERN Document Server

    Speziale, Simone

    2013-01-01

    We define and investigate a quantisation of null hypersurfaces in the context of loop quantum gravity on a fixed graph. The main tool we use is the parametrisation of the theory in terms of twistors, which has already proved useful in discussing the interpretation of spin networks as the quantization of twisted geometries. The classical formalism can be extended in a natural way to null hypersurfaces, with the Euclidean polyhedra replaced by null polyhedra with space-like faces, and SU(2) by the little group ISO(2). The main difference is that the simplicity constraints present in the formalims are all first class, and the symplectic reduction selects only the helicity subgroup of the little group. As a consequence, information on the shapes of the polyhedra is lost, and the result is a much simpler, abelian geometric picture. It can be described by an Euclidean singular structure on the 2-dimensional space-like surface defined by a foliation of space-time by null hypersurfaces. This geometric structure is na...

  18. Metabolism of isothiocyanates in individuals with positive and null GSTT1 and M1 genotypes after drinking watercress juice.

    Science.gov (United States)

    Dyba, Marcin; Wang, Antai; Noone, Anne-Michelle; Goerlitz, David; Shields, Peter; Zheng, Yun-Ling; Rivlin, Richard; Chung, Fung-Lung

    2010-12-01

    Isothiocyanates (ITCs) derived from cruciferous vegetables have been shown to be promising agents against cancer in human cell culture, animal models, and in epidemiological studies. Several epidemiological studies have demonstrated an inverse relationship between intake of dietary isothiocyanates and the risk of cancers, particularly lung, colon, and breast. More importantly, the protective effects of dietary ITCs appear to be influenced by glutathione S-transferase (GST) genotype; specifically, individuals with glutathione S-transferase theta 1 (GSTT1) and glutathione S-transferase Mu 1 (GSTM1) null are better protected than those with GSTT1 and M1 positive. Although the majority of studies, especially those conducted in populations exposed to ITC rich diets, demonstrated such effects, there are a few studies that showed opposite or no association. While evidence for the interactions of dietary ITCs with GST genes is relatively strong, the reasons for the differential effects remain unclear. In this study, we examined one possible mechanism: whether subjects with null genotypes excrete ITCs at a slower rate than those with positive genotypes after drinking watercress juice, a rich source of ITCs. A total of 48 subjects, 28 GSTT1 and M1 positive and 20 null genotypes were enrolled in the study. The rates of excretion were determined using five urine samples collected over a period of 24 h after drinking watercress juice. No statistically significant differences in the rates of isothiocyanate excretion and the time of peak excretion were observed between the two tested groups having positive and null genotypes. GSTT1 and M1 genotypes are not likely to be involved in the rate of excretion of ITCs in watercress. The demonstrated differences in protection among subjects with the two genotypes are not likely due to differences in overall ITC excretion rates, however, excretion rates of ITCs other than PEITC need to be investigated. Other yet to be identified mechanism

  19. Análise de polimorfismos nos genes CYP1A1, CYP17, COMT, GSTM1, receptor de estrogênios e progesterona em mulheres com carcinoma de ovário

    OpenAIRE

    Leite,Daniela Batista

    2009-01-01

    Objectives: To evaluate the association between polymorphisms of cytochrome P450c17 (CYP17), progesterone receptor (PROGINS), gluthatione S-transferase (GSTM1), Catechol-O-methyl transferase (COMT), and cytochrome P450c1A1 CYP1A1) genes in patients with and without ovarian cancer and to analyze the eventual association of these polymorphisms with clinical and pathological variables. Methods: A total of 103 ovarian cancer patients were seen at the Oncological Surgery Outpatients Clinic, Depart...

  20. Effects of genetic polymorphisms of CYP1A1, CYP2E1, GSTM1, and GSTT1 on the urinary levels of 1-hydroxypyrene and 2-naphthol in aircraft maintenance workers.

    Science.gov (United States)

    Lee, C Y; Lee, J Y; Kang, J W; Kim, H

    2001-09-15

    This study was undertaken to investigate the effects of genetic polymorphisms of the cytochrome P450 1A1 (CYP1A1) and 2E1 (CYP2E1), and glutathione S-transferases mu (GSTM1) and theta (GSTT1) on urinary 1-hydroxypyrene and 2-naphthol levels, and to estimate the level of exposure to polycyclic aromatic hydrocarbons (PAHs) in aircraft maintenance workers. In 218 Korean aircraft maintenance workers, the geometric means of urinary 1-hydroxypyrene and 2-naphthol were 0.32 and 3.25 micromol/mol creatinine, respectively. These urinary concentrations were approximately at the upper limit of the general population. Mean urinary 2-naphthol concentrations were significantly different between smokers and non-smokers. CYP1A1 and GSTM1 were statistically significant in analyses on both 1-hydroxypyrene and 2-naphthol levels among smokers. The results suggest that smoking has more profound effects on urinary PAH metabolites than does genetic polymorphisms in this population, and that CYP1A1 and GSTM1 activity might be related to the metabolism of 1-hydroxypyrene and 2-naphthol.

  1. Association of glutathione S-transferase T1 and M1 gene polymorphisms with ischemic stroke risk in the Chinese Han population

    Institute of Scientific and Technical Information of China (English)

    Rui Wang; Yan Wang; Junhong Wang; Kun Yang

    2012-01-01

    Atherosclerosis plays an important role in ischemic stroke, and oxidative stress participates in the entire process of atherosclerosis. Glutathione S-transferase (GST) acting with other antioxidant enzymes can eliminate reactive oxygen species and protect cells against oxidative damage. To assess the association of glutathione S-transferase (GSTT1 and GSTM1) gene polymorphisms with ischemic stroke in the Chinese Han population, the present study selected 315 patients with ischemic stroke and 210 healthy controls for comparison. GSTT1 and GSTM1 genotypes were determined using polymerase chain reactions, electrophoresis and imaging analysis. No obvious evidence of GSTT1-null, GSTM1-null and GSTT1/GSTM1-double null genotype distribution differences was found between case and control groups or between genders. Subgroup analysis showed that the risk of stroke was increased when hypertension was accompanied by GSTT1-null (odds ratio (OR) = 2.996, P < 0.001) and GSTM1-null (OR = 3.680, P < 0.001) genotypes; diabetes mellitus was accompanied by GSTT1-null (OR = 1.860, P = 0.031) and GSTM1-null (OR = 2.444, P = 0.002) genotypes, and smokers showed a GSTT1-null genotype (OR = 2.276, P = 0.003). GSTT1- and GSTM1-null genotypes may interact synergistically with hypertension, diabetes mellitus and smoking to increase the incidence risk of ischemic stroke.

  2. Genetic polymorphism of T6235C mutation in 3 non-coding region of CYP1A1 and GSTM1 genes and lung cancer susceptibility in the Mongolian population

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Objective To estimate the relative risk for lung cancer associated with genetic polymorphism of T6235C mutation in 3' non-coding region(MspⅠ)of cytochrome P450 1A1(CYP1A1)and glutathione S-transferase M1(GSTM1)in the Mongolian population in Inner Mongolian Region of China.Methods Polymerase chain reaction-restriction fragment length polymorphism(PCR-RFLP)and multiplex PCR methods were used to analyze blood samples obtained from 263 case subjects and 263 control subjects to determine their genotypes for CYP1...

  3. Cytogenetic damage in Turkish coke oven workers exposed to polycyclic aromatic hydrocarbons: Association with CYP1A1, CYP1B1, EPHX1, GSTM1, GSTT1, and GSTP1 gene polymorphisms.

    Science.gov (United States)

    Ada, Ahmet Oguz; Demiroglu, Canan; Yilmazer, Meltem; Suzen, Halit Sinan; Demirbag, Ali Eba; Efe, Sibel; Alemdar, Yilmaz; Iscan, Mumtaz; Burgaz, Sema

    2013-09-01

    The aim of this study was to determine the frequencies of chromosomal aberrations (CA) and cytochalasin-blocked micronuclei (CBMN) in peripheral blood lymphocytes from Turkish coke oven workers and the influence of CYP1A1, CYP1B1, EPHX1, GSTM1, GSTT1, and GSTP1 gene polymorphisms on these biomarkers. Cytogenetic analysis showed that occupational exposure significantly increased the CA and CBMN frequencies. Gene polymorphisms, on the other hand, did not affect CA or CBMN in either exposed or control subjects. However, due to the limited sample size, our findings need to be verified in future studies with a larger sample.

  4. In vitro generated Rh(null) red cells recapitulate the in vivo deficiency: a model for rare blood group phenotypes and erythroid membrane disorders.

    Science.gov (United States)

    Cambot, Marie; Mazurier, Christelle; Canoui-Poitrine, Florence; Hebert, Nicolas; Picot, Julien; Clay, Denis; Picard, Véronique; Ripoche, Pierre; Douay, Luc; Dubart-Kupperschmitt, Anne; Cartron, Jean-Pierre

    2013-05-01

    Lentiviral modification combined with ex vivo erythroid differentiation was used to stably inhibit RhAG expression, a critical component of the Rh(rhesus) membrane complex defective in the Rh(null) syndrome. The cultured red cells generated recapitulate the major alterations of native Rh(null) cells regarding antigen expression, membrane deformability, and gas transport function, providing the proof of principle for their use as model of Rh(null) syndrome and to investigate Rh complex biogenesis in human primary erythroid cells. Using this model, we were able to reveal for the first time that RhAG extinction alone is sufficient to explain ICAM-4 and CD47 loss observed on native Rh(null) RBCs. Together with the effects of RhAG forced expression in Rh(null) progenitors, this strongly strengthens the hypothesis that RhAG is critical to Rh complex formation. The strategy is also promising for diagnosis purpose in order to overcome the supply from rare blood donors and is applicable to other erythroid defects and rare phenotypes, providing models to dissect membrane biogenesis of multicomplex proteins in erythroid cells, with potential clinical applications in transfusion medicine.

  5. Genotipificación de polimorfismos moleculares en los genes CYP2E1, GSTM1 y GSTT1 para evaluar susceptibilidad a Cáncer gastrointestinal en una población paisa

    Directory of Open Access Journals (Sweden)

    Castaño CE.

    2001-06-01

    Full Text Available Entre los años 2001 y 2002 se recogieron 40 muestras de pacientes diagnosticados con cáncergastrointestinal en los departamentos de Antioquia y Caldas, a los cuales se les determinó elgenotipo molecular para los genes CYP2E1, GSTM1 y GSTT1 en sangre y se les realizó una entre-vista para analizar su consumo de alcohol, cigarrillo y alimentos quemados y/o embutidos, ya queestudios previos en otras poblaciones han sugerido la asociación de algunos polimorfismos de estos genes (en combinación o no con factores ambientales, con una predisposición a la enfermedad. Por tanto, se comparó estadísticamente las frecuencias genotípicas con las de unapoblación de controles sanos apareada con los casos por edad y sexo, y se observó la suscep-tibilidad a cáncer gastrointestinal, mediante el análisis de asociación a polimorfismos en los genesque codifican para las enzimas CYP2E1, GSTM1 Y GSTT1 del metabolismo de xenobióticos.

  6. THE STUDY OF THE RELATIONSHIP BETWEEN GLUTATHIONE'S-TRANSFERASE M1, T1 GENOTYPES AND THE ISK OF CERVICAL CANCER%GSTM1及GSTT1基因多态性与宫颈癌关系的研究

    Institute of Scientific and Technical Information of China (English)

    周芩; 王金桃; 邵淑丽; 马晓晨; 丁玲

    2006-01-01

    目的:探讨GSTM1及GSTT1基因多态性与宫颈癌发生的关系.方法:采用以医院为基础的病例对照及分子流行病学研究方法,应用多重PCR技术检测125例宫颈癌病例和125例子宫肌瘤对照的GSTM1和GSTT1基因型.结果:病例组GSTM1基因纯合缺失率为58.4%,显著高于对照组43.2%(x2=5.777,P=0.016);GSTT1基因纯合缺失率在病例组和对照组分别为53.6%和44.0%,差别无统计学意义(x2=2.305,P=0.129);GSTM1和GSTT1联合缺失者患宫颈癌的危险性是两基因同时存在者的2.588倍(95%CI=1.285~5.212).结论:GSTM1基因纯合缺失或GSTM1、GSTT1联合缺失可能与宫颈癌的发生有关.

  7. Genetic Polymorphisms of Phase II Metabolic Enzymes and Lung Cancer Susceptibility in a Population of Central South China

    Directory of Open Access Journals (Sweden)

    Han-chun Chen

    2006-01-01

    Full Text Available A case-control study was conducted for analyzing the genetic polymorphisms of phase II metabolic enzymes in 97 patients with lung cancer and 197 healthy subjects from Han ethnic group of Hunan Province located in Central South China. The results showed that the frequencies of glutathione S-transferase (GST M1-null (GSTM1- or GSTT1-null (GSTT1- genotype alone, or combined form of both in lung cancer patients were significantly higher than those of the controls. Genotypes of combining GSTP1 mutant/GSTM1(- or GSTP1 mutant/GSTT1(- led to high risk of lung cancer. Individuals carrying any two or all three of GSTM1(-, GSTT1(- and GSTP1 mutant genotypes have a distinctly increased risk of lung cancer when compared to those with GSTM1 present (GSTM1+: GSTM1+/+ or GSTM1+/−, GSTT1 present (GSTT1+: GSTT1+/+ or GSTT1+/− and GSTP1 wild genotypes. Furthermore, individuals possessing combined genotypes of N-acetyltransferase 2 (NAT2 rapid acetylator, GSTP1 mutant and both GSTT1(- and GSTM1(- have a remarkably higher lung cancer risk than those carrying combined NAT2 slow acetylator genotype, GSTP1 wild genotype and both GSTT1(+ and GSTM1(+ genotypes. All these findings suggest that the genetic polymorphisms of phase II metabolic enzymes affect the susceptibility of lung cancer in the Han ethnic group of Central South China.

  8. Geometry of null hypersurfaces

    CERN Document Server

    Jezierski, J

    2004-01-01

    We review some basic natural geometric objects on null hypersurfaces. Gauss-Codazzi constraints are given in terms of the analog of canonical ADM momentum which is a well defined tensor density on the null surface. Bondi cones are analyzed with the help of this object.

  9. GST null genotype and antioxidants: Risk indicators for oral pre-cancer and cancer

    Directory of Open Access Journals (Sweden)

    Bathi Renuka

    2009-01-01

    Full Text Available Objectives : This study was undertaken to detect the gene polymorphism of detoxification enzymes and estimate the antioxidant enzyme status in patients with oral cancer, oral leukoplakia and oral submucous fibrosis (OSF. Materials and Methods : The GSTM1 and GSTT1 gene polymorphism was evaluated using polymerase chain reaction; the antioxidant enzyme was estimated using biochemical methods. Statistical analyses were performed using student t-test and odds-ratio to estimate relative risk (RR. Results : The RR at 95% confidence interval (CI for GSTM1 and GSTT1 was statistically significant for all groups. The mean values of glutathione were significantly raised in all groups. The mean values of ceruloplasmin and malonaldehyde was statistically significant among cancer and OSF patients but was insignificant in smokers and cases with leukoplakia. Conclusion : Several genes perform the same function which implies the need to test for several genetic polymorphisms to identify individuals at high risk. The level of antioxidant enzymes correlate with the degree of oxidative damage. The need for further studies is emphasised.

  10. Verified Null-Move Pruning

    CERN Document Server

    David-Tabibi, Omid

    2008-01-01

    In this article we review standard null-move pruning and introduce our extended version of it, which we call verified null-move pruning. In verified null-move pruning, whenever the shallow null-move search indicates a fail-high, instead of cutting off the search from the current node, the search is continued with reduced depth. Our experiments with verified null-move pruning show that on average, it constructs a smaller search tree with greater tactical strength in comparison to standard null-move pruning. Moreover, unlike standard null-move pruning, which fails badly in zugzwang positions, verified null-move pruning manages to detect most zugzwangs and in such cases conducts a re-search to obtain the correct result. In addition, verified null-move pruning is very easy to implement, and any standard null-move pruning program can use verified null-move pruning by modifying only a few lines of code.

  11. Study on the Relationship between the Glutathiones-transferase Gene Deletion Environmental Factors and Susceptibility to Gastric Carcinoma%GSTM1基因多态性与环境暴露和胃癌易感性关系的研究

    Institute of Scientific and Technical Information of China (English)

    姜又红; 鞠振宇; 任常山; 吕庆点; 魏巍

    2000-01-01

    采用流行病学调查方法对41例胃癌患者及41例非消化道疾病和非肿瘤对照者,筛选出致胃癌的环境危险因素;应用多聚酶链式反应(polymerase chain reaction,PCR)方法对其外周血细胞进行GSTM1基因检测.结果发现胃癌组GSTM1基因缺失率为58.5%,对照组为34.1%,两组差异有统计学意义(X2=3.972,p<0.05,OR=2.724).同时暴露于吸烟,经常吃皮蛋、咸蛋,吃硬果类食物,吃臭豆腐、腐乳各环境危险因素中,病例组GSTM1基因缺失率均显著高与对照组(X2=4.628,p<0.05,OR=4.039;X2=4.426,P<0.05,OR=7.000;X2=6.312,P<0.05,OR=5.564;Fisher检验P=0.031,OR=4.550).提示GSTM1基因缺失与胃癌易感性有关;GSTM1基因缺失与吸烟,经常暴露于吃皮蛋、咸蛋,吃硕果类食物,吃臭豆腐、腐乳这些环境危险因素中对胃癌有协同作用.

  12. Influence of class M1 glutathione S-transferase (GST Mu) polymorphism on GST M1 gene expression level and tumor size in oral squamous cell carcinoma.

    Science.gov (United States)

    Koch, F P; Kämmerer, P W; Kämmerer, P; Al-Nawas, B; Brieger, J

    2010-02-01

    Glutathione S-transferases (GST) are antioxidant enzymes and oxidative stress markers in oral carcinogenesis. They present a system of polymorphic proteins. Some variants are associated with increased sensitivity to toxic compounds, as it is known for the GSTM1-null variant allele. However, the influence of the GSTM1 allele variant genotype on GSTM1-mRNA quantity in oral squamous cell carcinoma (OSCC) and normal mucosa as well as the impact on prognosis remains unclear. The genotype for GSTM1 (mutation vs. wild type) was determined by polymerase chain reaction (PCR) using genomic DNA extracted from peripheral blood from 28 OSCC patients. From the same patients, 28 pairs of OSCC cells and normal oral mucosal cells were obtained by brush biopsy. mRNA was extracted from these paired samples and the expression levels of GSTM1 were examined by real-time reverse transcriptase qPCR (RT-qPCR). The mRNA expression of the OSCC samples was normalized against an external standard, as well as to the corresponding normal mucosa. The coincidence of GSTM1 genotype and GSTM1-mRNA-expression level was examined. In 15 patients (54%), the null genotype GSTM1 was present. In the GSTM1-null allele group, the GSTM1 gene expression level was determined at 1.63 (mean: 3.08; SD 3.4) folds vs. 3.6 (mean: 10.5; SD 14.2) folds in the group with the positive genotype (p=0.06), if calibrated vs. individual normal mucosa. More T3 and T4 OSCCs (+38%), higher UICC stadia (+38%) and more lymphatic metastasis (+28%) were seen in the group with the negative allele. Furthermore, positive GSTM1 genotype and enhanced GSTM1 gene expression was accompanied with increased tumor size, lymphatic metastasis status and UICC stadium. A coincidence of null type GSTM1 and lowered GSTM1 gene expression was observed. The larger tumors and more frequent lymph node metastases in this group could be explained by the insufficient cell protection by GST.

  13. 中国人群GSTM1基因多态性与非吸烟肺癌发病风险的Meta分析%Correlation between glutathione S-transferase M1 polymorphism and risk of lung cancer in non-smoking Chinese: A meta-analysis

    Institute of Scientific and Technical Information of China (English)

    包晓玲; 杨磊

    2012-01-01

    Objective To assess the correlation between glutathione S-transferase Ml (GSTM1) polymorphism and risk of developing lung cancer in non-smoking Chinese by meta-analysis. Methods Papers on the correlation between GSTM1 polymorphism and risk of lung cancer in non-smoking Chinese were searched from CNKI (1979-2011), CQVIP (1989-2011), Chinese Biomedical Literature Database (1979-2011), Wanfang Database (1998-2011), EMbase (1900-2011) and PubMed (1966-2011). Results Sixteen papers on case-control study were included in this study, involving 818 non-smoking patients with lung cancer and 921 healthy controls. Meta-analysis showed that the risk of developing lung cancer was significantly higher in non-smoking Chinese with GSTM1 -deficit genotype than in those without GSTMl-deficit genotype (OR=1.65, 95%CI=1.34, 2.04). Egger's and Begg's analysis showed that the risk of developing lung cancer was 1.48-fold (95%CI=1.14, 1.91) and 2.03-fold (95%CI=1.42, 2.90) higher in Chinese of both South and North China with GSTMl-deficit genotype than that in controls. Conclusion The risk of developing lung cancer is significantly higher in non-smoking Chinese with GSTMl-deficit genotype.%目的 利用Meta 分析方法评价谷胱甘肽S- 转移酶M1(glutathione S-transferase M1,GSTM1) 基因多态性与中国人群非吸烟肺癌发病的相关性.方法 检索中国期刊全文数据库(1979-2011)、维普中文科技期刊数据库(1989-2011)、中国生物医学文献数据库(1979-2011)、万方数据库(1998-2011)、EMbase(1900-2011) 和PubMed (1966-2011) 数据库,收集有关中国人群GSTM1 基因多态性与非吸烟肺癌关系的研究.结果 共纳入16 篇文献对照研究,包括非吸烟肺癌患者818 例,对照组921 例.Meta 分析结果显示:GSTM1 缺失基因型的中国人群患非吸烟肺癌的风险明显增高(OR=1.65,95%CI=1.34,2.04).亚组分析发现,具有GSTM1 缺失基因型的中国南方和北方人群罹患非吸烟肺癌

  14. Visible Nulling Coronagraph

    Science.gov (United States)

    Shao, M.; Samuel, R.; Wallace, K.; Levine, B.

    2007-06-01

    To date, nulling coronography has achieved the deepest level of starlight suppression than any other coronagraphic technique. The terms starlight suppression and contrast are often used interchangeably and incorrectly. At 3.5 lambda/D the airy function sidelobes has dropped to 0.001 of the stellar flux. Starlight suppression of 1e-7 will then produce a speckle pattern with a contrast of 1e-10. This paper describes three topics in nulling coronagraphs. The first is starlight suppression of 1.1e-7 in laser light, the level of star light suppression needed for 1e-10 contrast. A similar experiment in broadband (16%) white light has demonstrated ~1.2e-6 suppression. Both experiments were starlight suppression using a single mode optical fiber. Starlight suppression to 1e-6~1e-7 requires wavefront measurements with sub-angstrom level accuracy. This is most easily done with a wavefront sensor that works with light after the coronagraph rather than the bright starlight in front of the coronagraph. Our nulling coronagraph uses a post coronagraphic interferometer to perform two functions, 1) measure the wavefront and provide an correction/error signal for the deformable mirror, and 2) post coronagraph PSF subtraction. We show that the post coronagraph interferometer has very significant SNR advantages over other post coronagraph approaches such as speckle nulling. A secondary function of the post coronagraphic wavefront sensor is that since it measures the amplitude and phase of the wavefront of the starlight after exiting the coronagraph, that amp*exp(i*phi) can be used to estimate the residual speckle pattern for subsequent PSF subtraction. By measuring the PSF at the same time as we're measuring the science image, the stability requirements can be relaxed by many orders of magnitude. (over rotating the telescope around the line of sight for example). The post coronagraph interferometer is being used in three projects, the PICTURE project (coronagraph behind a 60 cm

  15. Polymorphism of glutathione S-transferase mu 1 and theta 1 genes and hepatocellular carcinoma in southern Guangxi, China

    Institute of Scientific and Technical Information of China (English)

    Zhuo-Lin Deng; Yi-Ping Wei; Yun Ma

    2005-01-01

    AIM: Glutathione S-transferase mu 1 (GSTM1) and theta 1(GSTT1) genes are involved in the metabolism of a wide range of carcinogens, but deletions of the genes are commonly found in the population. The present study was undertaken to evaluate the association between GSTM1 and GSTT1 gene polymorphisms and hepatocellular carcinoma (HCC) risk.METHODS: The genetic polymorphisms were studied at an aflatoxin highly contaminated region in Guangxi, China.Polymerase chain reaction (PCR) technique was used to detect the presence or absence of the GSTM1 and GSTT1 genes in blood samples. The case group was composed of 181 patients of HCC identified by the pathologists and the control group was composed of 360 adults without any tumor.RFSULTS: The frequencies of GSTM1 and GSTT1 null genotypes in the control were 47.8% and 42.7%, while those in the HCC group were 64.6% and 59.7%, respectively. The differences between HCC group and control group were very significant (P<0.01). GSTM1 and GSTT1 combined null genotypes in HCC group and control group were 38.2% and 18.5%respectively, and the difference was significant (P<0.05).CONCLUSION: The GSTM1 and GSTT1 null genotypes are associated with an increased risk of HCC in a special geographic environment. Combination of the two null genotypes in an individual is substantially increased twice the risk of HCC.

  16. STUDY OF THE DELETION MUTATION OF GLUTATHIONE S TRANSFERASE M1 GENE AND ITS ROLE IN SUSCEPTIBILITY TO HEPATOCELLULAR CARCINOMA

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Objection: To investigate the glutathione S transferase M1 (GSTM1) gene inherent deletion and its relation to prevalence of hepatocellular carcinoma (HCC) in Guangxi, China. Methods: The GSTM1 gene polymorphism of 120 HCC patients and 100 healthy subjects both from the same high aflatoxin B1 (AFB1) contaminated area were detected using PCR technique with special primers. Another 40 patients from AFB1 low risk area were also tested. Results: In HCC high risk area, it was found that the frequencies of GSTM1 null genotype in HCC patients and healthy subjects were 59% and 51% respectively, with no significant difference. However, the frequency of GSTM1-null genotype in control group from AFB1 low risk area was lower than those from high risk area (P<0.01). Conclusion: Populations in this HCC endemic region show a higher rate of GSTM1-null genotype, which may be partially responsible for the susceptibility to AFB1 induced HCC. But the detoxification effect of GSTM1 alone is not sufficient to resist the genetic toxicity of AFB1, especially in those people who expose to excess AFB1. The GSTM1 gene deletion would not be suitable as an independent predictor of susceptibility to HCC.

  17. Radiant Temperature Nulling Radiometer

    Science.gov (United States)

    2002-01-01

    A nulling, self-calibrating infrared radiometer is being developed for use in noncontact measurement of temperature in any of a variety of industrial and scientific applications. This instrument is expected to be especially well-suited to measurement of ambient or near-ambient temperature and, even more specifically, for measuring the surface temperature of a natural body of water. Although this radiometer would utilize the long-wavelength infrared (LWIR) portion of the spectrum (wavelengths of 8 to 12 m), its basic principle of operation could also be applied to other spectral bands (corresponding to other temperature ranges) in which the atmosphere is transparent and in which design requirements for sensitivity and temperature-measurement accuracy could be satisfied. The underlying principle of nulling and self-calibration is the same as that of a typical microwave radiometer, but because of differences between the characteristics of signals in the infrared and microwave spectral regions, the principle must be implemented in a different way. A detailed description of the instrument including an infrared photodetector equipped with focusing input optics [e.g., lens(es) and/or mirrors] and an input LWIR band-pass filter is presented.

  18. Gravitational action with null boundaries

    CERN Document Server

    Lehner, Luis; Poisson, Eric; Sorkin, Rafael D

    2016-01-01

    We present a complete discussion of the boundary term in the action functional of general relativity when the boundary includes null segments in addition to the more usual timelike and spacelike segments. We confirm that ambiguities appear in the contribution from a null segment, because it depends on an arbitrary choice of parametrization for the generators. We also show that similar ambiguities appear in the contribution from a codimension-two surface at which a null segment is joined to another (spacelike, timelike, or null) segment. The parametrization ambiguity can be tamed by insisting that the null generators be affinely parametrized; this forces each null contribution to the boundary action to vanish, but leaves intact the fredom to rescale the affine parameter by a constant factor on each generator. Once a choice of parametrization is made, the ambiguity in the joint contributions can be eliminated by formulating well-motivated rules that ensure the additivity of the gravitational action. Enforcing t...

  19. Polymorphisms of the cytochrome P450 and glutathion s-transferase genes associated with lung cancer susceptibility for the residents in high radon-exposed area%肿瘤易感基因CYP4501A1和GSTm1多态性与高氡暴露地区居民肺癌关系研究

    Institute of Scientific and Technical Information of China (English)

    夏英; 王浩; 孙粉珍; 王海军; 巨雅洁; 毛玲; 王琳; 孙全富; 尚兵; 吕慧敏; 冯顺治; 程同心; 崔宏星; 齐雪松; 王利平

    2008-01-01

    目的 研究高氡暴露地区居民肺癌易感基因CYP4501A1和GSTm1多态性的变化规律,探讨这2种基因多态性与肺癌及环境因素之间的关系.方法 按病例-对照的研究方法从甘肃省庆阳地区选择原发性肺癌病例和相匹配的对照人群进行室内氡、钍射气的测量,并应用PCR-RFLP和PCR方法检测2种基因的多态性.结果 研究表明,携带杂合型CYP1A1(w/m)或缺失型GSTm1(-)基因与野生型基因的个体比较,肺癌发病风险分别为1.46倍(95%CI为0.72~2.95)和1.28倍(95%CI为0.67~2.41).同时携带两种突变基因型的个体,肺癌发病风险为2.00倍(95%CI为0.72~5.58),重度吸烟者肺癌的发病风险会增至2.14倍(95%CI为0.35~13.12).居住在室内氡、钍射气累积有效剂量50~100 mSv并携带突变型CYP1A1(w/m)或GSTm1(-)基因的个体患肺癌的风险分别为2.63倍(95%CI为0.21~31.34)和3.50倍(95%CI为0.31~39.12).有肿瘤家族史的人群肺癌发病风险是3.75倍(95%CI为1.51~9.29),差异有统计学意义.结论 杂合型CYP1A1(w/m)和突变型GSTm1(-)基因是较重要的肺癌风险因子,尤其在有效剂量50~100 mSy和2种突变基因的协同作用时.%Objective To investigate whether the CYP1A1 and GSTm1 genetic polymorphism are agsoaiate with lung cancer in the residents of high radon exposure area.Methods A case-control method was performed,lung cancer and control individials were selected from Qingyang county of Gansu Province.The indoor radon and thoron concentration were measured.CYP1A1 and GSTm1 genetic polymorphism were detected by PCR-RFLP or multiplex-PCR.Results The risk of developing lung cancer for people carried with heterozygous CYP1A1(w/m)and mutation genotype GSTm1(-)were 1.46(95%CI 0.72-2.95)and 1.28(95%CI 0.67-2.41)higher than wide type.respectively.The risk of lung carccr for combination of CYP1A1(w/m)and GSTm1(-)increased to 2.00 fold(95%CI 0.72-5.58),the heavy smokers who carried with heterozygous of CYP1A1(w

  20. A Null Space Approach for Solving Nonlinear Complementarity Problems

    Institute of Scientific and Technical Information of China (English)

    Pu-yan Nie

    2006-01-01

    In this work, null space techniques are employed to tackle nonlinear complementarity problems(NCPs). NCP conditions are transform into a nonlinear programming problem, which is handled by null space algorithms. The NCP conditions are divided into two groups. Some equalities and inequalities in an NCP are treated as constraints. While other equalities and inequalities in an NCP are to be regarded as objective function.Two groups are all updated in every step. Null space approaches are extended to nonlinear complementarity problems. Two different solvers are employed for an NCP in an algorithm.

  1. On the randomness of pulsar nulls

    Science.gov (United States)

    Redman, Stephen L.; Rankin, Joanna M.

    2009-05-01

    Pulsar nulling is not always a random process; most pulsars, in fact, null non-randomly. The Wald-Wolfowitz statistical runs test is a simple diagnostic that pulsar astronomers can use to identify pulsars that have non-random nulls. It is not clear at this point how the dichotomy in pulsar nulling randomness is related to the underlying nulling phenomenon, but its nature suggests that there are at least two distinct reasons that pulsars null.

  2. The Nullness Analyser of julia

    Science.gov (United States)

    Spoto, Fausto

    This experimental paper describes the implementation and evaluation of a static nullness analyser for single-threaded Java and Java bytecode programs, built inside the julia tool. Nullness analysis determines, at compile-time, those program points where the null value might be dereferenced, leading to a run-time exception. In order to improve the quality of software, it is important to prove that such situation does not occur. Our analyser is based on a denotational abstract interpretation of Java bytecode through Boolean logical formulas, strengthened with a set of denotational and constraint-based supporting analyses for locally non-null fields and full arrays and collections. The complete integration of all such analyses results in a correct system of very high precision whose time of analysis remains in the order of minutes, as we show with some examples of analysis of large software.

  3. NULL Convention Floating Point Multiplier

    OpenAIRE

    Anitha Juliette Albert; Seshasayanan Ramachandran

    2015-01-01

    Floating point multiplication is a critical part in high dynamic range and computational intensive digital signal processing applications which require high precision and low power. This paper presents the design of an IEEE 754 single precision floating point multiplier using asynchronous NULL convention logic paradigm. Rounding has not been implemented to suit high precision applications. The novelty of the research is that it is the first ever NULL convention logic multiplier, designed to p...

  4. Gravitational action with null boundaries

    Science.gov (United States)

    Lehner, Luis; Myers, Robert C.; Poisson, Eric; Sorkin, Rafael D.

    2016-10-01

    We present a complete discussion of the boundary term in the action functional of general relativity when the boundary includes null segments in addition to the more usual timelike and spacelike segments. We confirm that ambiguities appear in the contribution from a null segment, because it depends on an arbitrary choice of parametrization for the generators. We also show that similar ambiguities appear in the contribution from a codimension-two surface at which a null segment is joined to another (spacelike, timelike, or null) segment. The parametrization ambiguity can be tamed by insisting that the null generators be affinely parametrized; this forces each null contribution to the boundary action to vanish, but leaves intact the fredom to rescale the affine parameter by a constant factor on each generator. Once a choice of parametrization is made, the ambiguity in the joint contributions can be eliminated by formulating well-motivated rules that ensure the additivity of the gravitational action. Enforcing these rules, we calculate the time rate of change of the action when it is evaluated for a so-called "Wheeler-DeWitt patch" of a black hole in asymptotically anti de Sitter space. We recover a number of results cited in the literature, obtained with a less complete analysis.

  5. NULL Convention Floating Point Multiplier

    Directory of Open Access Journals (Sweden)

    Anitha Juliette Albert

    2015-01-01

    Full Text Available Floating point multiplication is a critical part in high dynamic range and computational intensive digital signal processing applications which require high precision and low power. This paper presents the design of an IEEE 754 single precision floating point multiplier using asynchronous NULL convention logic paradigm. Rounding has not been implemented to suit high precision applications. The novelty of the research is that it is the first ever NULL convention logic multiplier, designed to perform floating point multiplication. The proposed multiplier offers substantial decrease in power consumption when compared with its synchronous version. Performance attributes of the NULL convention logic floating point multiplier, obtained from Xilinx simulation and Cadence, are compared with its equivalent synchronous implementation.

  6. NULL convention floating point multiplier.

    Science.gov (United States)

    Albert, Anitha Juliette; Ramachandran, Seshasayanan

    2015-01-01

    Floating point multiplication is a critical part in high dynamic range and computational intensive digital signal processing applications which require high precision and low power. This paper presents the design of an IEEE 754 single precision floating point multiplier using asynchronous NULL convention logic paradigm. Rounding has not been implemented to suit high precision applications. The novelty of the research is that it is the first ever NULL convention logic multiplier, designed to perform floating point multiplication. The proposed multiplier offers substantial decrease in power consumption when compared with its synchronous version. Performance attributes of the NULL convention logic floating point multiplier, obtained from Xilinx simulation and Cadence, are compared with its equivalent synchronous implementation.

  7. Phase-Occultation Nulling Coronagraphy

    CERN Document Server

    Lyon, Richard G; Clampin, Mark; Petrone, Peter

    2015-01-01

    The search for life via characterization of earth-like planets in the habitable zone is one of the key scientific objectives in Astronomy. We describe a new phase-occulting (PO) interferometric nulling coronagraphy (NC) approach. The PO-NC approach employs beamwalk and freeform optical surfaces internal to the interferometer cavity to introduce a radially dependent plate scale difference between each interferometer arm (optical path) that nulls the central star at high contrast while transmitting the off-axis field. The design is readily implemented on segmented-mirror telescope architectures, utilizing a single nulling interferometer to achieve high throughput, a small inner working angle (IWA), sixth-order or higher starlight suppression, and full off-axis discovery space, a combination of features that other coronagraph designs generally must trade. Unlike previous NC approaches, the PO-NC approach does not require pupil shearing; this increases throughput and renders it less sensitive to on-axis common-mo...

  8. Analyses of Genetic Variations of Glutathione S-Transferase Mu1 and Theta1 Genes in Bangladeshi Tannery Workers and Healthy Controls

    Directory of Open Access Journals (Sweden)

    Jobaida Akther

    2016-01-01

    Full Text Available Glutathione S-transferases (GSTs belong to a group of multigene detoxification enzymes, which defend cells against oxidative stress. Tannery workers are at risk of oxidative damage that is usually detoxified by GSTs. This study investigated the genotypic frequencies of GST Mu1 (GSTM1 and GST Theta1 (GSTT1 in Bangladeshi tannery workers and healthy controls followed by their status of oxidative stress and total GST activity. Of the 188 individuals, 50.0% had both GSTM1 and GSTT1 (+/+, 12.2% had GSTM1 (+/−, 31.4% had GSTT1 (−/+ alleles, and 6.4% had null genotypes (−/− with respect to both GSTM1 and GSTT1 alleles. Among 109 healthy controls, 54.1% were double positive, 9.2% had GSTM1 allele, 32.1% had GSTT1 allele, and 4.6% had null genotypes. Out of 79 tannery workers, 44.3% were +/+, 16.8% were +/−, 30.5% were −/+, and 8.4% were −/−. Though the polymorphic genotypes or allelic variants of GSTM1 and GSTT1 were distributed among the study subjects with different frequencies, the differences between the study groups were not statistically significant. GST activity did not vary significantly between the two groups and also among different genotypes while level of lipid peroxidation was significantly higher in tannery workers compared to controls irrespective of their GST genotypes.

  9. Fracture characterisation using geoelectric null-arrays

    Science.gov (United States)

    Falco, Pierik; Negro, François; Szalai, Sándor; Milnes, Ellen

    2013-06-01

    The term "geoelectric null-array" is used for direct current electrode configurations yielding a potential difference of zero above a homogeneous half-space. This paper presents a comparative study of the behaviour of three null-arrays, midpoint null-array (MAN), Wenner-γ null-array and Schlumberger null-array in response to a fracture, both in profiling and in azimuthal mode. The main objective is to determine which array(s) best localise fractures or best identify their orientation. Forward modelling of the three null-arrays revealed that the Wenner-γ and Schlumberger null-arrays localise vertical fractures the most accurately, whilst the midpoint null-array combined with the Schlumberger null-array allows accurate orientation of a fracture. Numerical analysis then served as a basis to interpret the field results. Field test measurements were carried out above a quarry in Les Breuleux (Switzerland) with the three null-arrays and classical arrays. The results were cross-validated with quarry-wall geological mapping. In real field circumstances, the Wenner-γ null-array proved to be the most efficient and accurate in localising fractures. The orientations of the fractures according to the numerical results were most efficiently determined with the midpoint null-array, whilst the Schlumberger null-array adds accuracy to the results. This study shows that geoelectrical null-arrays are more suitable than classical arrays for the characterisation of fracture geometry.

  10. Null eikonal helices and Null eikonal slant helices in the 4-dimensional Lorentzian manifold

    OpenAIRE

    Zıplar, Evren

    2014-01-01

    In this paper, we define the notion of eikonal helix and eikonal slant helix for null curves in the 4-dimensional Lorentzian manifold M 1 4 and give a characterization for the null curve to be the null eikonal helix. Moreover, we indicate an important relation between the null eikonal helix and null eikonal slant helix and find the axis of the null eikonal helix. We obtain some relationships between the curvatures of these curves.

  11. Balloon Exoplanet Nulling Interferometer (BENI)

    Science.gov (United States)

    Lyon, Richard G.; Clampin, Mark; Woodruff, Robert A.; Vasudevan, Gopal; Ford, Holland; Petro, Larry; Herman, Jay; Rinehart, Stephen; Carpenter, Kenneth; Marzouk, Joe

    2009-01-01

    We evaluate the feasibility of using a balloon-borne nulling interferometer to detect and characterize exosolar planets and debris disks. The existing instrument consists of a 3-telescope Fizeau imaging interferometer with 3 fast steering mirrors and 3 delay lines operating at 800 Hz for closed-loop control of wavefront errors and fine pointing. A compact visible nulling interferometer is under development which when coupled to the imaging interferometer would in-principle allow deep suppression of starlight. We have conducted atmospheric simulations of the environment above 100,000 feet and believe balloons are a feasible path forward towards detection and characterization of a limited set of exoplanets and their debris disks. Herein we will discuss the BENI instrument, the balloon environment and the feasibility of such as mission.

  12. Parasitic interference in nulling interferometry

    CERN Document Server

    Matter, Alexis; Danchi, William C; Lopez, Bruno; Absil, Olivier

    2013-01-01

    Nulling interferometry aims to detect faint objects close to bright stars. Its principle is to produce a destructive interference along the line-of-sight so that the stellar flux is rejected, while the flux of the off-axis source can be transmitted. In practice, various instrumental perturbations can degrade the nulling performance. Any imperfection in phase, amplitude, or polarization produces a spurious flux that leaks to the interferometer output and corrupts the transmitted off-axis flux. One of these instrumental pertubations is the crosstalk phenomenon, which occurs because of multiple parasitic reflections inside transmitting optics, and/or diffraction effects related to beam propagation along finite size optics. It can include a crosstalk of a beam with itself, and a mutual crosstalk between different beams. This can create a parasitic interference pattern, which degrades the intrinsic transmission map - or intensity response - of the interferometer. In this context, we describe how this instrumental ...

  13. Null-field radiationless sources.

    Science.gov (United States)

    Hurwitz, Elisa; Gbur, Greg

    2014-11-15

    It is shown that it is in principle possible to produce combined sources of polarization and magnetization that are not only radiationless but that have any (and sometimes several) of the four microscopic or macroscopic electromagnetic fields exactly zero. The conditions that such a "null-field radiationless source" must satisfy are derived, and examples are given for several cases. The implications for transformation optics and invisibility physics in general are discussed.

  14. Stringy Resolutions of Null Singularities

    Energy Technology Data Exchange (ETDEWEB)

    Fabinger, Michal

    2003-02-06

    We study string theory in supersymmetric time-dependent backgrounds. In the framework of general relativity, supersymmetry for spacetimes without flux implies the existence of a covariantly constant null vector, and a relatively simple form of the metric. As a result, the local nature of any such spacetime can be easily understood. We show that we can view any such geometry as a sequence of solutions to lower-dimensional Euclidean gravity. If we choose the lower-dimensional solutions to degenerate at some light-cone time, we obtain null singularities, which may be thought of as generalizations of the parabolic orbifold singularity. We find that in string theory, many such null singularities get repaired by {alpha}{prime}-corrections--in particular, by worldsheet instantons. As a consequence, the resulting string theory solutions do not suffer from any instability. Even though the CFT description of these solutions is not always valid, they can still be well understood after taking the effects of light D-branes into account; the breakdown of the worldsheet conformal field theory is purely gauge-theoretic, not involving strong gravitational effects.

  15. An analysis of radio pulsar nulling statistics

    Science.gov (United States)

    Biggs, James D.

    1992-01-01

    Survival analysis methods are used to seek correlations between the fraction of null pulsars and other pulsar characteristics for an ensemble of 72 radio pulsars. The strongest correlation is found between the null fraction and the pulse period, suggesting that nulling is a manifestation of a faltering emission mechanism. Correlations are also found between the fraction of null pulses and other parameters that have a strong dependence on the pulse period. The results presented here suggest that nulling is broad-band and may ultimately be explained in terms of polar cap models of pulsar emission.

  16. Areas and volumes for null cones

    CERN Document Server

    Grant, James D E

    2010-01-01

    Motivated by recent work of Choquet-Bruhat, Chrusciel, and Martin-Garcia, we prove monotonicity properties and comparison results for the area of slices of the null cone of a point in a Lorentzian manifold. We also prove volume comparison results for subsets of the null cone analogous to the Bishop-Gromov relative volume monotonicity theorem and Guenther's volume comparison theorem. We briefly discuss how these estimates may be used to control the null second fundamental form of slices of the null cone in Ricci-flat Lorentzian four-manifolds with null curvature bounded above.

  17. Null Similar Curves with Variable Transformations in Minkowski 3-space

    OpenAIRE

    Önder, Mehmet

    2012-01-01

    In this study, we define a family of null curves in Minkowski 3-space and called null similar curves. We obtain some properties of these special curves. We show that two null curves are null similar curves if and only if these curves form a null Bertrand pair. Moreover, we obtain that the family of null geodesics and null helices form the families of null similar curves with variable transformation.

  18. Interpreting null findings from trials of alcohol brief interventions

    Directory of Open Access Journals (Sweden)

    Nick eHeather

    2014-07-01

    Full Text Available The effectiveness of alcohol brief intervention (ABI has been established by a succession of meta-analyses but, because the effects of ABI are small, null findings from randomized controlled trials are often reported and can sometimes lead to skepticism regarding the benefits of ABI in routine practice. This article first explains why null findings are likely to occur under null hypothesis significance testing (NHST due to the phenomenon known as ‘the dance of the p-values’. A number of misconceptions about null findings are then described, using as an example the way in which the results of the primary care arm of a recent cluster randomized trial of ABI in England (the SIPS project have been misunderstood. These misinterpretations include the fallacy of ‘proving the null hypothesis’ that lack of a significant difference between the means of sample groups can be taken as evidence of no difference between their population means, and the possible effects of this and related misunderstandings of the SIPS findings are examined. The mistaken inference that reductions in alcohol consumption seen in control groups from baseline to follow-up are evidence of real effects of control group procedures is then discussed and other possible reasons for such reductions, including regression to the mean, research participation effects, historical trends, and assessment reactivity, are described. From the standpoint of scientific progress, the chief problem about null findings under the conventional NHST approach is that it is not possible to distinguish ‘evidence of absence’ from ‘absence of evidence’. By contrast, under a Bayesian approach, such a distinction is possible and it is explained how this approach could classify ABIs in particular settings or among particular populations as either truly ineffective or as of unknown effectiveness, thus accelerating progress in the field of ABI research.

  19. Interpreting null findings from trials of alcohol brief interventions.

    Science.gov (United States)

    Heather, Nick

    2014-01-01

    The effectiveness of alcohol brief intervention (ABI) has been established by a succession of meta-analyses but, because the effects of ABI are small, null findings from randomized controlled trials are often reported and can sometimes lead to skepticism regarding the benefits of ABI in routine practice. This article first explains why null findings are likely to occur under null hypothesis significance testing (NHST) due to the phenomenon known as "the dance of the p-values." A number of misconceptions about null findings are then described, using as an example the way in which the results of the primary care arm of a recent cluster-randomized trial of ABI in England (the SIPS project) have been misunderstood. These misinterpretations include the fallacy of "proving the null hypothesis" that lack of a significant difference between the means of sample groups can be taken as evidence of no difference between their population means, and the possible effects of this and related misunderstandings of the SIPS findings are examined. The mistaken inference that reductions in alcohol consumption seen in control groups from baseline to follow-up are evidence of real effects of control group procedures is then discussed and other possible reasons for such reductions, including regression to the mean, research participation effects, historical trends, and assessment reactivity, are described. From the standpoint of scientific progress, the chief problem about null findings under the conventional NHST approach is that it is not possible to distinguish "evidence of absence" from "absence of evidence." By contrast, under a Bayesian approach, such a distinction is possible and it is explained how this approach could classify ABIs in particular settings or among particular populations as either truly ineffective or as of unknown effectiveness, thus accelerating progress in the field of ABI research.

  20. Cartan's Equivalence Method and Null coframes in General Relativity

    CERN Document Server

    Gallo, E; Kozameh, C; Gallo, Emanuel; Iriondo, Mirta; Kozameh, Carlos

    2004-01-01

    Using Cartan's equivalence method for point transformations we obtain from first principles the conformal geometry associated with third order ODEs and a special class of PDEs in two dimensions. We explicitly construct the null tetrads of a family of Lorentzian metrics, the conformal group in three and four dimensions and the so called normal metric connection. A special feature of this connection is that the non vanishing components of its torsion depend on one relative invariant, the (generalized) W\\"unschmann Invariant. We show that the above mentioned construction naturally contains the Null Surface Formulation of General Relativity.

  1. On the Penrose inequality along null hypersurfaces

    CERN Document Server

    Mars, Marc

    2015-01-01

    The null Penrose inequality, i.e. the Penrose inequality in terms of the Bondi energy, is studied by introducing a funtional on surfaces and studying its properties along a null hypersurface $\\Omega$ extending to past null infinity. We prove a general Penrose-type inequality which involves the limit at infinity of the Hawking energy along a specific class of geodesic foliations called Geodesic Asymptotic Bondi (GAB), which are shown to always exist. Whenever, this foliation approaches large spheres, this inequality becomes the null Penrose inequality and we recover the results of Ludvigsen-Vickers and Bergqvist. By exploiting further properties of the functional along general geodesic foliations, we introduce an approach to the null Penrose inequality called Renormalized Area Method and find a set of two conditions which implies the validity of the null Penrose inequality. One of the conditions involves a limit at infinity and the other a condition on the spacetime curvature along the flow. We investigate the...

  2. Agreement and Null Subjects in German L2 Development: New Evidence from Reaction-Time Experiments.

    Science.gov (United States)

    Clahsen, Harald; Hong, Upyong

    1995-01-01

    Reports on reaction time experiments investigating subject-verb agreement and null subjects in 33 Korean learners of German and a control group of 20 German native speakers. Results found that the two phenomena do not covary in the Korean learners, indicating that properties of agreement and null subjects are acquired separately from one another.…

  3. The Association between GSTT1 and GSTM1 Gene Polymorphism and Nerve Conduction Velocity in Workers Exposed to 1-Bromopropane%谷胱甘肽S转移酶基因多态性对1-溴丙烷接触者神经传导速度的影响

    Institute of Scientific and Technical Information of China (English)

    王强毅; 李卫华; 丁训诚; 金泰廙

    2007-01-01

    [目的]探讨谷胱甘肽S转移酶基因多态性对1-溴丙烷(1-BP)接触者神经传导速度的影响.[方法]选择116名1-BP接触工人为接触组,133名无1-BP接触史的工人为对照组,用神经电生理检测技术测定工人的运动神经传导速度(MCV)、感觉神经传导速度(SCV)和末端潜伏期(DL),用等位基因特异性扩增(ASA)方法检测两组GSTT1和GSTM1基因型的分布.[结果]GSTT1基因多态性和1-BP接触对工人的SCV和DL的影响有交互作用,SNK两两比较结果显示,与对照组GSTT1基因携带者相比,接触组中GSTT1基因缺失型工人的SCV明显减慢[分别为(45.3±5.0)m/s和(40.1±5.3)m/s]、DL明显延长[分别为(6.3±1.3)ms和(8.3±2.0)ms],差别有统计学意义(P<0.05);去除交互项后的两因素方差分析显示,GSTT1基因多态性对工人的MCV有独立的影响(P<0.05).未发现GSTM1基因多态性对接触者外周神经传导速度有影响.[结论]GSTT1基因多态性与接触者对1-BP外周神经毒性的易感性有关.

  4. The Importance of Proving the Null

    Science.gov (United States)

    Gallistel, C. R.

    2009-01-01

    Null hypotheses are simple, precise, and theoretically important. Conventional statistical analysis cannot support them; Bayesian analysis can. The challenge in a Bayesian analysis is to formulate a suitably vague alternative, because the vaguer the alternative is (the more it spreads out the unit mass of prior probability), the more the null is…

  5. Collapsing spherical null shells in general relativity

    Directory of Open Access Journals (Sweden)

    S Khakshournia

    2011-03-01

    Full Text Available In this work, the gravitational collapse of a spherically symmetric null shell with the flat interior and a charged Vaidya exterior spacetimes is studied. There is no gravitational impulsive wave present on the null hypersurface which is shear-free and contracting. It follows that there is a critical radius at which the shell bounces and starts expanding.

  6. Causal cells: spacetime polytopes with null hyperfaces

    CERN Document Server

    Neiman, Yasha

    2012-01-01

    We consider polyhedra and 4-polytopes in Minkowski spacetime - in particular, null polyhedra with zero volume, and 4-polytopes that have such polyhedra as their hyperfaces. We present the basic properties of several classes of null-faced 4-polytopes: 4-simplices, "tetrahedral diamonds" and 4-parallelotopes. We propose a "most regular" representative of each class. The most-regular parallelotope is of particular interest: its edges, faces and hyperfaces are all congruent, and it features both null hyperplanes and null segments. A tiling of spacetime with copies of this polytope can be viewed alternatively as a lattice with null edges, such that each point is at the intersection of four lightrays in a tetrahedral pattern. We speculate on the relevance of this construct for discretizations of curved spacetime and for quantum gravity.

  7. IRAN: interferometric remapped array nulling

    Science.gov (United States)

    Aristidi, Eric; Vakili, Farrokh; Abe, Lyu; Belu, Adrian; Lopez, Bruno; Lanteri, Henri; Schutz, A.; Menut, Jean-Luc

    2004-10-01

    This paper describes a method of beam-combination in the so-called hypertelescope imaging technique recently introduced by Labeyrie in optical interferometry. The method we propose is an alternative to the Michelson pupil reconfiguration that suffers from the loss of the classical object-image convolution relation. From elementary theory of Fourier optics we demonstrate that this problem can be solved by observing in a combined pupil plane instead of an image plane. The point-source intensity distribution (PSID) of this interferometric "image" tends towards a psuedo Airy disc (similar to that of a giant monolithic telescope) for a sufficiently large number of telescopes. Our method is applicable to snap-shot imaging of extended sources with a field comparable to the Airy pattern of single telescopes operated in a co-phased multi-aperture interferometric array. It thus allows to apply conveniently pupil plane coronagraphy. Our technique called Interferometric Remapped Array Nulling (IRAN) is particularly suitable for high dynamic imaging of extra-solar planetary companions, circumstellar nebulosities or extra-galactic objects where long baseline interferometry would closely probe the central regions of AGNs for instance.

  8. Magnetic Nulls in the Earth's Magnetotail

    Science.gov (United States)

    Eriksson, Elin; Vaivads, Andris; Khotyaintsev, Yuri; Markidis, Stefano; André, Mats; Fu, Huishan; Karlsson, Tomas

    2015-04-01

    Regions with vanishing magnetic field, also referred to as magnetic nulls, are of high interest in plasma physics. Near magnetic nulls particles become unmagnetized and can by interacting with electric fields be accelerated up to high energies. Magnetic nulls have been observed and studied before using different methods for a few events. Here we present a statistical study of magnetic nulls in the Earth's magnetotail. In addition we study the role of magnetic field disturbances on the magnetic null identification. We study the magnetic nulls using full resolution data from all of the Cluster satellites when their maximum separation is less than one ion inertial length (approximately 1000 km). This is only fulfilled in 2003 when the maximum spacecraft separation is approximately 250 km. The magnetic nulls are not found using the more common method of Poincaré index. Instead we create a box surrounding the tetrahedron defined by the positions of the spacecrafts. If the positions of the magnetic nulls, using Taylor expansion, are within this box, they are saved for further analysis. All together 23 time intervals are found using this method and two error constraints. We find most of the nulls in the magnetotail current sheet, but a few of them are found at the magnetopause. We identify magnetic null types and currents associated with them. We present a detailed analysis of one example from August 6, 2003 00:45:40:00 UT - 00:45:41:05 UT when the satellites are in the magnetotail. Based on a linear magnetic field model created using parameters taken from the real data, we demonstrate the effect of magnetic field disturbance on the magnetic null identification. We show that magnetic disturbances of large enough amplitude can lead to a change in the magnetic null type, consistent with the data example. Therefore we suggest that for magnetic null type identification an additional constraint based on magnetic field disturbance amplitude have to be introduced. The obtained

  9. Role of Plasmodium vivax Duffy-binding protein 1 in invasion of Duffy-null Africans.

    Science.gov (United States)

    Gunalan, Karthigayan; Lo, Eugenia; Hostetler, Jessica B; Yewhalaw, Delenasaw; Mu, Jianbing; Neafsey, Daniel E; Yan, Guiyun; Miller, Louis H

    2016-05-31

    The ability of the malaria parasite Plasmodium vivax to invade erythrocytes is dependent on the expression of the Duffy blood group antigen on erythrocytes. Consequently, Africans who are null for the Duffy antigen are not susceptible to P. vivax infections. Recently, P. vivax infections in Duffy-null Africans have been documented, raising the possibility that P. vivax, a virulent pathogen in other parts of the world, may expand malarial disease in Africa. P. vivax binds the Duffy blood group antigen through its Duffy-binding protein 1 (DBP1). To determine if mutations in DBP1 resulted in the ability of P. vivax to bind Duffy-null erythrocytes, we analyzed P. vivax parasites obtained from two Duffy-null individuals living in Ethiopia where Duffy-null and -positive Africans live side-by-side. We determined that, although the DBP1s from these parasites contained unique sequences, they failed to bind Duffy-null erythrocytes, indicating that mutations in DBP1 did not account for the ability of P. vivax to infect Duffy-null Africans. However, an unusual DNA expansion of DBP1 (three and eight copies) in the two Duffy-null P. vivax infections suggests that an expansion of DBP1 may have been selected to allow low-affinity binding to another receptor on Duffy-null erythrocytes. Indeed, we show that Salvador (Sal) I P. vivax infects Squirrel monkeys independently of DBP1 binding to Squirrel monkey erythrocytes. We conclude that P. vivax Sal I and perhaps P. vivax in Duffy-null patients may have adapted to use new ligand-receptor pairs for invasion.

  10. The Steinhaus property and Haar-null sets

    CERN Document Server

    Dodos, Pandelis

    2010-01-01

    It is shown that if $G$ is an uncountable Polish group and $A\\subseteq G$ is a universally measurable set such that $A^{-1}A$ is meager, then the set $T_l(A)=\\{\\mu\\in P(G): \\mu(gA)=0 \\text{for all} g\\in G\\}$ is co-meager. In particular, if $A$ is analytic and not left Haar-null, then $1\\in\\mathrm{Int}(A^{-1}AA^{-1}A)$.

  11. On smoothness-asymmetric null infinities

    Energy Technology Data Exchange (ETDEWEB)

    Valiente Kroon, Juan Antonio [School of Mathematical Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS (United Kingdom)

    2006-05-21

    We discuss the existence of asymptotically Euclidean initial data sets for the vacuum Einstein field equations which would give rise (modulo an existence result for the evolution equations near spatial infinity) to developments with a past and a future null infinity of different smoothness. For simplicity, the analysis is restricted to the class of conformally flat, axially symmetric initial data sets. It is shown how the free parameters in the second fundamental form of the data can be used to satisfy certain obstructions to the smoothness of null infinity. The resulting initial data sets could be interpreted as those of some sort of (nonlinearly) distorted Schwarzschild black hole. Their developments would be that they admit a peeling future null infinity, but at the same time have a polyhomogeneous (non-peeling) past null infinity.

  12. New null screen design for corneal topography

    Science.gov (United States)

    Campos-García, Manuel; Estrada-Molina, Amilcar; Díaz-Uribe, Rufino

    2011-09-01

    In this work we report the design of a null screen for corneal topography. Here we assume that the corneal surface is an ellipsoid with a diameter of 12 mm and a curvature radius of 7.8 mm. To avoid the difficulties in the alignment of the test system due to the face contour (eyebrows, nose, or eyelids), we design a conical null-screen with spots (similar to ellipses) drawn on it in such a way that its image, which is formed by reflection on the test surface, becomes an exact radial array of circular spots if the surface is perfect. Additionally, we performed a numerical simulation introducing Gaussian random errors in the coordinates of the centroids of the spots on the image plane, and in the coordinates of the sources (spots on the null-screen) in order to obtain the conical null-screen that reduces the error in the evaluation of the topography.

  13. Scientists Find a Magnetic Null in Nature

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ An international team has found the first in situ evidence for the existance of a null point in the central area of magnetic reconnection. The discovery was reported in the July issue of Nature Physics.

  14. High-contrast Nulling Interferometry Techniques Project

    Data.gov (United States)

    National Aeronautics and Space Administration — "We are developing rotating-baseline nulling-interferometry techniques and algorithms on the single-aperture Hale and Keck telescopes at near-infrared wavelengths,...

  15. Faddeev Null Plane Model of Proton

    CERN Document Server

    D'Araújo, W R B; Frederico, T

    1998-01-01

    The proton is formulated as a relativistic system of three constituent quarks interacting via a zero-range two-body force in the null-plane. The covariance of the null-plane Faddeev-like equation under kinematical front-form boosts is discussed. A simplified three-boson model of the nucleon wave-function is obtained numerically. The proton electric form-factor reproduces the experimental data for low momentum transfers and qualitatively describes the asymptotic region.

  16. Null vectors of the $WBC_2$ algebra

    CERN Document Server

    Bajnok, Z

    1994-01-01

    Using the fusion principle of Bauer et al. we give explicit expressions for some null vectors in the highest weight representations of the \\bc algebra in two different forms. These null vectors are the generalization of the Virasoro ones described by Benoit and Saint-Aubin and analogues of the $W_3$ ones constructed by Bowcock and Watts. We find connection between quantum Toda models and the fusion method.

  17. Characterization of Null Geodesics on Kerr Spacetimes

    CERN Document Server

    Paganini, Claudio F; Oancea, Marius A

    2016-01-01

    We consider null geodesics in the domain of outer communication of a sub-extremal Kerr spacetime. We show, that most fundamental properties of null geodesics can be represented in one plot. In particular one can see immediately that the ergoregion and trapping are separated in phase space. Furthermore we show that from the point of view of any timelike observer outside of a black hole, trapping can be understood as a smooth set of spacelike directions on the observers' celestial sphere.

  18. Null-sissemakse - eraisikule riskantne / Tõnu Tramm

    Index Scriptorium Estoniae

    Tramm, Tõnu, 1968-

    2005-01-01

    Ilmunud ka: Delovõje Vedomosti 20. apr. lk. 26. Hansaliising ja Ühisliising käivitasid kampaania, mille käigus pakutakse uusi kuni 250 000 krooni maksvaid autosid null-sissemaksega. Kommenteerib ASi SEB Ühisliising arendusdirektor Ove Muuk. Tabel: Null-sissemaksega auto tuleb kallim. Lisad: Kuidas saavutada võimalikult väike kuumakse?; Kuidas maksta võimalikult vähe intressi? Vt. samas: Argo Rebane: Liisingufirmast saab parema hinna

  19. Phase-only nulling for transmit antenna

    Science.gov (United States)

    Hussain, Moayyed A.; Yu, Kai-Bor

    1999-11-01

    This paper describes a technique for transmit antenna nulling for low-cost large sparse phased array radar system. Radar system described includes an array of elemental antennas, each with a transmit/receive (T/R) module. The T/R modules are operated at or near maximum output to achieve maximum CD-to-RF efficiency. A phase controller controls the phase shift, which are imparted by each module to its signal, to form a mainbeam and its associated sidelobes. A perturbation phase generator adds phase shifts computed, to form wide nulls in the sidelobe structure. The nulls are achieved at very minimal loss of gain, in the order of fraction of a dB. The speed of obtaining these nulls in real time allows a rapid steering of these nulls in a hostile environment. The thinned aperture allow designing a light weigh mobile system. In radar context, these nulls may be placed on a source of ground clutter, a set of jammers or a set of undesirable radio sources.

  20. The Curious Case of Null Warped Space

    CERN Document Server

    Anninos, Dionysios; de Buyl, Sophie; Detournay, Stéphane; Guica, Monica

    2010-01-01

    We initiate a comprehensive study of a set of solutions of topologically massive gravity known as null warped anti-de Sitter spacetimes. These are pp-wave extensions of three-dimensional anti-de Sitter space. We first perform a careful analysis of the linearized stability of black holes in these spacetimes. We find two qualitatively different types of solutions to the linearized equations of motion: the first set has an exponential time dependence, the second - a polynomial time dependence. The solutions polynomial in time induce severe pathologies and moreover survive at the non-linear level. In order to make sense of these geometries, it is thus crucial to impose appropriate boundary conditions. We argue that there exists a consistent set of boundary conditions that allows us to reject the above pathological modes from the physical spectrum. The asymptotic symmetry group associated to these boundary conditions consists of a centrally-extended Virasoro algebra. Using this central charge we can account for th...

  1. Modular Hamiltonians on the null plane and the Markov property of the vacuum state

    Science.gov (United States)

    Casini, Horacio; Testé, Eduardo; Torroba, Gonzalo

    2017-09-01

    We compute the modular Hamiltonians of regions having the future horizon lying on a null plane. For a CFT this is equivalent to regions with a boundary of arbitrary shape lying on the null cone. These Hamiltonians have a local expression on the horizon formed by integrals of the stress tensor. We prove this result in two different ways, and show that the modular Hamiltonians of these regions form an infinite dimensional Lie algebra. The corresponding group of unitary transformations moves the fields on the null surface locally along the null generators with arbitrary null line dependent velocities, but act non-locally outside the null plane. We regain this result in greater generality using more abstract tools on the algebraic quantum field theory. Finally, we show that modular Hamiltonians on the null surface satisfy a Markov property that leads to the saturation of the strong sub-additive inequality for the entropies and to the strong super-additivity of the relative entropy.

  2. The Emergence, Motion, and Disappearance of Magnetic Null Points

    OpenAIRE

    Murphy, Nicholas; Parnell, Clare; Haynes, Andrew; Pontin, David

    2013-01-01

    Magnetic reconnection frequently occurs at and around magnetic null points. We derive exact expressions for the motion of a magnetic null point in a smoothly varying magnetic field. We define xn as the position of a null, U = dxn/dt as the null's velocity, and M as the Jacobian matrix of the magnetic field at the null. By evaluating the derivative of the magnetic field following the motion of the null, we find the null velocity to be U = -M-1 ∂B/∂t with all quantities evaluated ...

  3. Null Subjects in European and Brazilian Portuguese

    Directory of Open Access Journals (Sweden)

    Pilar Barbosa

    2005-12-01

    Full Text Available The goals of this paper are twofold: a to provide a structural account of the effects of the informal ‘Avoid Pronoun Principle’, proposed in Chomsky (1981: 65 for the Null Subject Languages (NSLs, and b to compare, in European and Brazilian Portuguese (EP and BP, the distribution of the third person pronouns in its full and null forms, to check whether in written corpora BP incorporates signs of the ongoing loss of the null subject, largely attested in its contemporary spoken language. The strong theoretical claim is that in the Romance non-NSLs the pre-verbal subject is sitting in Spec of IP, while in the Romance NSLs it is Clitic Left-Dislocated (or is extracted by A-bar movement if it belongs to a restricted set of non-referential quantified expressions. The paper provides quantitative evidence that BP is losing the properties associated with the Null Subject Parameter. In its qualitative analysis, it shows that the contrasts between EP and BP are easily accounted for if the two derivations are assumed and if the null subjects in the two varieties are considered to be of a different nature: a pronoun in EP and a pronominal anaphor in BP.

  4. Two Roads to the Null Energy Condition

    CERN Document Server

    Parikh, Maulik

    2015-01-01

    The null energy condition has sweeping consequences in general relativity. I argue here that it has been misunderstood as a property exclusively of matter, when in fact it arises only in a theory of both matter and gravity. I then derive an equivalent geometric formulation of the null energy condition from worldsheet string theory, where it arises beautifully as simply Einstein's equations in two dimensions. But further, I show that this condition also has a thermodynamic origin, following from a local version of the second law of thermodynamics, applied to gravitational entropy. Thus, far from being an incidental property of matter, the validity of the null energy condition hints at the deep dual origins of gravity.

  5. Null Geodesics in Brane World Scenarios

    Institute of Scientific and Technical Information of China (English)

    ZHANG Li-Feng; ZHANG Yuan-Zhong

    2004-01-01

    We study the null bulk geodesic motion in the brane world in which the bulk metric has an un-stabilized extra spatial dimension. We find that the null bulk geodesic motion as observed on the 3-brane with Z2 symmetry would be a timelike geodesic motion even though there exists an extra non-gravitational force in contrast with the case of the stabilized extra spatial dimension. In other words the presence of the extra non-gravitational force would not violate thc Z2 symmetry.

  6. Magnetized Emergent Universe with Null Radiation Flow

    Science.gov (United States)

    Singh, J. K.; Rani, Sarita

    2016-01-01

    In this paper, we study the Bianchi type-I cosmological model in a different basic form incorporating with null radiation flow with the perfect fluid in the presence as well as absence of a source free magnetic field. A set of new exact solutions of Einstein field equations are obtained in both the cases. We observe that the emergent universe model with null radiation flow approaches to de-sitter universe at late time obeying the same rate of expansion in presence and absence of the magnetic field.

  7. Null Mutations of Group A Streptococcus Orphan Kinase RocA: Selection in Mouse Infection and Comparison with CovS Mutations in Alteration of In Vitro and In Vivo Protease SpeB Expression and Virulence.

    Science.gov (United States)

    Feng, Wenchao; Minor, Dylan; Liu, Mengyao; Li, Jinquan; Ishaq, Suzanne L; Yeoman, Carl; Lei, Benfang

    2017-01-01

    Group A Streptococcus (GAS) acquires mutations of the virulence regulator CovRS in human and mouse infections, and these mutations result in the upregulation of virulence genes and the downregulation of the protease SpeB. To identify in vivo mutants with novel phenotypes, GAS isolates from infected mice were screened by enzymatic assays for SpeB and the platelet-activating factor acetylhydrolase Sse, and a new type of variant that had enhanced Sse expression and normal levels of SpeB production was identified (the variants had a phenotype referred to as enhanced Sse activity [Sse(A+)] and normal SpeB activity [SpeB(A+)]). Sse(A+) SpeB(A+) variants had transcript levels of CovRS-controlled virulence genes comparable to those of a covS mutant but had no covRS mutations. Genome resequencing of an Sse(A+) SpeB(A+) isolate identified a C605A nonsense mutation in orphan kinase gene rocA, and 6 other Sse(A+) SpeB(A+) isolates also had nonsense mutations or small indels in rocA RocA and CovS mutants had similar levels of enhancement of the expression of CovRS-controlled virulence genes at the exponential growth phase; however, mutations of RocA but not mutations of CovS did not result in the downregulation of speB transcription at stationary growth phase or in subcutaneous infection of mice. GAS with RocA and CovS mutations caused greater enhancement of the expression of hasA than spyCEP in mouse skin infection than wild-type GAS did. RocA mutants ranked between wild-type GAS and CovS mutants in skin invasion, inhibition of neutrophil recruitment, and virulence in subcutaneous infection of mice. Thus, GAS RocA mutants can be selected in subcutaneous infections in mice and exhibit gene expression patterns and virulences distinct from those of CovS mutants. The findings provide novel information for understanding GAS fitness mutations in vivo, virulence gene regulation, in vivo gene expression, and virulence. Copyright © 2016 American Society for Microbiology.

  8. Molecular identification of rare FY*Null and FY*X alleles in Caucasian thalassemic family from Sardinia.

    Science.gov (United States)

    Manfroi, Silvia; Scarcello, Antonio; Pagliaro, Pasqualepaolo

    2015-10-01

    Molecular genetic studies on Duffy blood group antigens have identified mutations underlying rare FY*Null and FY*X alleles. FY*Null has a high frequency in Blacks, especially from sub-Saharan Africa, while its frequency is not defined in Caucasians. FY*X allele, associated with Fy(a-b+w) phenotype, has a frequency of 2-3.5% in Caucasian people while it is absent in Blacks. During the project of extensive blood group genotyping in patients affected by hemoglobinopathies, we identified FY*X/FY*Null and FY*A/FY*Null genotypes in a Caucasian thalassemic family from Sardinia. We speculate on the frequency of FY*X and FY*Null alleles in Caucasian and Black people; further, we focused on the association of FY*X allele with weak Fyb antigen expression on red blood cells and its identification performing high sensitivity serological typing methods or genotyping.

  9. Increased susceptibility of Nrf2-null mice to 1-bromopropane-induced hepatotoxicity.

    Science.gov (United States)

    Liu, Fang; Ichihara, Sahoko; Valentine, William M; Itoh, Ken; Yamamoto, Masayuki; Sheik Mohideen, Sahabudeen; Kitoh, Junzoh; Ichihara, Gaku

    2010-06-01

    1-Bromopropane (1-BP) was introduced as an alternative to ozone-depleting solvents. However, it was found to exhibit neurotoxicity, reproductive toxicity, and hepatotoxicity in rodents and neurotoxicity in human. However, the mechanisms underlying the toxicities of 1-BP remain elusive. The present study investigated the role of oxidative stress in 1-BP-induced hepatotoxicity using nuclear factor erythroid 2-related factor 2 (Nrf2)-null mice. Groups of 24 male Nrf2-null mice and 24 male wild-type (WT) C57BL/6J mice were each divided into three groups of eight and exposed to 1-BP at 0, 100, or 300 ppm for 8 h/day for 28 days by inhalation. Liver histopathology showed significantly larger area of necrosis in Nrf2-null mice relative to WT mice at the same exposure level. Nrf2-null mice also had greater malondialdehyde (MDA) levels, higher ratio of oxidized glutathione/reduced form of glutathione, and lower total glutathione content. The constitutive level and the increase in ratio per exposure level of glutathione S-transferase (GST) activity were lower in the liver of Nrf2-null mice than WT mice. Exposure to 1-BP at 300 ppm increased the messenger RNA levels of heme oxygenase-1 (HO-1), glutamate-cysteine ligase modifier subunit (GcLm), glutamate-cysteine synthetase (GcLc), glutathione reductase, and NAD(P)H: quinone oxidoreductase 1 (NQO1) in WT mice but not in Nrf2-null mice except for GST Yc2. Nrf2-null mice were more susceptible to 1-BP-induced hepatotoxicity. That oxidative stress plays a role in 1-BP hepatotoxicity is deduced from the low expression levels and activities of antioxidant enzymes and high MDA levels in Nrf2-null mice.

  10. The Emergence, Motion, and Disappearance of Magnetic Null Points

    Science.gov (United States)

    Murphy, Nicholas; Parnell, Clare; Haynes, Andrew; Pontin, David

    2013-10-01

    Magnetic reconnection frequently occurs at and around magnetic null points. We derive exact expressions for the motion of a magnetic null point in a smoothly varying magnetic field. We define xn as the position of a null, U = dxn/dt as the null's velocity, and M as the Jacobian matrix of the magnetic field at the null. By evaluating the derivative of the magnetic field following the motion of the null, we find the null velocity to be U = -M-1 ∂B/∂t with all quantities evaluated at the null point. For resistive MHD, this reduces to U =V (xn) - ηM-1∇2B. This expression indicates that any difference between the plasma flow velocity at the null and the velocity of the null itself is due to resistive diffusion of the magnetic field. Null points must diffuse in and out of existence. Null-null pairs first appear (or disappear) as a single degenerate null with singular M, and then instantaneously move apart (together) infinitely fast. An expression describing the motion of separators cannot depend solely on local parameters and must include information on connectivity changes due to reconnection along the entire field line.

  11. Infinite Blueshift of Charged Null Particles

    OpenAIRE

    Mann, R. B.; Sajko, W. N.

    1994-01-01

    We demonstrate that charged null particles can be infinitely blue\\-shifted in a Kerr-Newman spacetime. The surface of infinite blueshift can be outside of the ergosphere in a Kerr-Newman spacetime, and outside of the outer event horizon for a Reissner-Nordstrom spacetime. Implications for extensions of the standard model which incorporate charged neutrinos are discussed.

  12. Polarization nulling interferometry for exoplanet detection

    NARCIS (Netherlands)

    Spronck, J.; Pereira, S.F.; Braat, J.J.M.

    2006-01-01

    We introduce a new concept of nulling interferometer without any achromatic device, using polarization properties of light. This type of interferometer should enable a high rejection ratio in a theoretically unlimited spectral band. We analyze several consequences of the proposed design, notably, th

  13. The Null Hypothesis as the Research Hypothesis.

    Science.gov (United States)

    Myers, Barbara E.; Pohlmann, John T.

    A procedure was developed within hypothesis-testing logic that allows researchers to support a hypothesis that has traditionally been the statistical or null hypothesis. Four activities involved in attainment of this goal were discussed: (1) development of statistical logic needed to define the sampling distribution associated with the hypothesis…

  14. Gravitational collapse of a cylindrical null shell in vacuum

    Directory of Open Access Journals (Sweden)

    S. Khakshournia

    2008-03-01

    Full Text Available   Barrabès-Israel null shell formalism is used to study the gravitational collapse of a thin cylindrical null shell in vacuum. In general the lightlike matter shell whose history coincides with a null hypersurface is characterized by a surface energy density. In addition, a gravitational impulsive wave is present on this null hypersurface whose generators admit both the shear and expansion. In the case of imposing the cylindrical flatness the surface energy-momentum tensor of the matter shell on the null hypersurface vanishes and the null hyper- surface is just the history of the gravitational wave .

  15. Cardiac Characterization of sgca-Null Mice Using High Resolution Echocardiography.

    Science.gov (United States)

    Fayssoil, Abdallah; Renault, Gilles; Guerchet, Nicolas; Marchiol-Fournigault, Carmen; Fougerousse, Françoise; Richard, Isabelle

    2013-01-01

    Limb-girdle muscular dystrophy 2D (LGMD2D) is an inherited myogenic disorder belonging to the group of muscular dystrophies. Sgca-null mouse is a knock-out model of LGMD2D. Little is known about cardiac phenotype characterization in this model at different ages. We conducted a prospective study to characterize cardiac sgca-null mice phenotype using high resolution Doppler echocardiography at different ages. Conventional echocardiography was performed on anesthetised mice using a Vevo 770 (Visualsonics) with 30 MHz cardiac probe. Wild Type (WT) and sgca-null mice were scanned at 13, 15 and 17 months. From M-mode, we measured interventricular septal (IVS) wall thickness, posterior wall (PW) thickness, and end-left ventricular diameter in systolic and diastolic. From the above parameters, we calculated left ventricular (LV) shortening fraction (SF), LV ejection fraction (EF) and LV mass. At age 13 months, PW diastolic thickness was increased in sgca-null mice (0.89±0.14 mm vs 0.73±0.2 mm; P=0.020) and LV mass was higher in sgca-null mice (LV mass 205.2 mg vs 143 mg; P=0.001). We found also dilation of the LV (LVEDD: 4.84 mm vs 4.29 mm; P=0.019) in sgca-null mice. At age 15 months, dilation of the LV (LVEDD: 4.86 mm vs 4 mm; P=0.05) with an increase of the LV mass (165.7 mg vs 127.12; P=0.03) are found in sgca-null mice. At age 17 months, we found a decrease of the PW thickening (17% vs 30%; P=0.036). This work provides echocardiographic insights for the assessment of pharmaceutical therapies in sgca-null mice.

  16. Influence of choice of null network on small-world parameters of structural correlation networks.

    Science.gov (United States)

    Hosseini, S M Hadi; Kesler, Shelli R

    2013-01-01

    In recent years, coordinated variations in brain morphology (e.g., volume, thickness) have been employed as a measure of structural association between brain regions to infer large-scale structural correlation networks. Recent evidence suggests that brain networks constructed in this manner are inherently more clustered than random networks of the same size and degree. Thus, null networks constructed by randomizing topology are not a good choice for benchmarking small-world parameters of these networks. In the present report, we investigated the influence of choice of null networks on small-world parameters of gray matter correlation networks in healthy individuals and survivors of acute lymphoblastic leukemia. Three types of null networks were studied: 1) networks constructed by topology randomization (TOP), 2) networks matched to the distributional properties of the observed covariance matrix (HQS), and 3) networks generated from correlation of randomized input data (COR). The results revealed that the choice of null network not only influences the estimated small-world parameters, it also influences the results of between-group differences in small-world parameters. In addition, at higher network densities, the choice of null network influences the direction of group differences in network measures. Our data suggest that the choice of null network is quite crucial for interpretation of group differences in small-world parameters of structural correlation networks. We argue that none of the available null models is perfect for estimation of small-world parameters for correlation networks and the relative strengths and weaknesses of the selected model should be carefully considered with respect to obtained network measures.

  17. Statistics and accuracy of magnetic null identification in multispacecraft data

    Science.gov (United States)

    Eriksson, E.; Vaivads, A.; Khotyaintsev, Yu. V.; Khotyayintsev, V. M.; André, M.

    2015-09-01

    Complex magnetic topologies are ubiquitous in astrophysical plasmas. Analyzing magnetic nulls, regions of vanishing magnetic field, is one way to characterize 3-D magnetic topologies. Magnetic nulls are believed to be important in 3-D reconnection and turbulence. In the vicinity of a null, plasma particles become unmagnetized and can be accelerated to high energies by electric fields. We present the first statistical study of the occurrence of magnetic nulls and their types in the Earth's nightside magnetosphere. We are able to identify the nulls both in the tail and in the magnetopause current sheets. On average, we find one null for every few current sheet crossings. We show that the type identification of magnetic nulls may be sensitive to local fluctuations in the magnetic field. We develop and demonstrate a method to estimate the reliability of the magnetic null type identification.

  18. Dichotomies of the set of test measures of a Haar-null set

    CERN Document Server

    Dodos, Pandelis

    2010-01-01

    We prove that if $X$ is a Polish space and $F$ is a face of $P(X)$ with the Baire property, then $F$ is either a meager or a co-meager subset of $P(X)$. As a consequence we show that for every abelian Polish group $X$ and every analytic Haar-null set $A\\subseteq X$, the set of test measures $T(A)$ of $A$ is either meager or co-meager. We characterize the non-locally-compact groups as the ones for which there exists a closed Haar-null set $F\\subseteq X$ with $T(F)$ is meager. Moreover, we answer negatively a question of J. Mycielski by showing that for every non-locally-compact abelian Polish group and every $\\sigma$-compact subgroup $G$ of $X$ there exists a $G$-invariant $F_\\sigma$ subset of $X$ which is neither prevalent nor Haar-null.

  19. Statistics and accuracy of magnetic null identification in multispacecraft data

    OpenAIRE

    Eriksson, Elin; Vaivads, Andris; Khotyaintsev, Yuri V.; Khotyayintsev, V. M.; Andre, Mats

    2015-01-01

    Complex magnetic topologies are ubiquitous in astrophysical plasmas. Analyzing magnetic nulls, regions of vanishing magnetic field, is one way to characterize 3-D magnetic topologies. Magnetic nulls are believed to be important in 3-D reconnection and turbulence. In the vicinity of a null, plasma particles become unmagnetized and can be accelerated to high energies by electric fields. We present the first statistical study of the occurrence of magnetic nulls and their types in the Earth's nig...

  20. 'Proper acceleration' of a null geodesic in curved spacetime

    CERN Document Server

    Tian Gui Hua; Liang Can Bin

    2002-01-01

    Given a null geodesic in Minkowski spacetime, there exists a one-parameter family of observers in 'hyperbolic' motion which approaches the null geodesic as the parameter x sub 0 approaches zero. It is well known that the proper acceleration of the observers in the family approaches infinity as their world line approaches the null geodesic. The main purpose of this paper is to generalize this result to future-complete null geodesics in curved spacetimes.

  1. Blob dynamics in TORPEX poloidal null configurations

    Science.gov (United States)

    Shanahan, B. W.; Dudson, B. D.

    2016-12-01

    3D blob dynamics are simulated in X-point magnetic configurations in the TORPEX device via a non-field-aligned coordinate system, using an isothermal model which evolves density, vorticity, parallel velocity and parallel current density. By modifying the parallel gradient operator to include perpendicular perturbations from poloidal field coils, numerical singularities associated with field aligned coordinates are avoided. A comparison with a previously developed analytical model (Avino 2016 Phys. Rev. Lett. 116 105001) is performed and an agreement is found with minimal modification. Experimental comparison determines that the null region can cause an acceleration of filaments due to increasing connection length, but this acceleration is small relative to other effects, which we quantify. Experimental measurements (Avino 2016 Phys. Rev. Lett. 116 105001) are reproduced, and the dominant acceleration mechanism is identified as that of a developing dipole in a moving background. Contributions from increasing connection length close to the null point are a small correction.

  2. Latex allergy and filaggrin null mutations

    DEFF Research Database (Denmark)

    Carlsen, Berit C; Meldgaard, Michael; Hamann, Dathan

    2011-01-01

    Objectives Natural rubber latex (NRL) contains over 200 proteins of which 13 have been identified as allergens and the cause of type I latex allergy. Health care workers share a high occupational risk for developing latex allergy. Filaggrin null mutations increase the risk of type I sensitization...... in the cases in this study may not have occurred through direct skin contact but through the respiratory organs via latex proteins that are absorbed in glove powder and aerosolized......Objectives Natural rubber latex (NRL) contains over 200 proteins of which 13 have been identified as allergens and the cause of type I latex allergy. Health care workers share a high occupational risk for developing latex allergy. Filaggrin null mutations increase the risk of type I sensitizations...

  3. Collapse and bounce of null fluids

    CERN Document Server

    Creelman, Bradley

    2016-01-01

    Exact solutions describing the spherical collapse of null fluids can contain regions which violate the energy conditions. Physically the violations occur when the infalling matter continues to move inwards even when non-gravitational repulsive forces become stronger than gravity. In 1991 Ori proposed a resolution for these violations: spacetime surgery should be used to replace the energy condition violating region with an outgoing solution. The matter bounces. We revisit and implement this proposal for the more general Husain null fluids. We find that: 1) generically there is a thin shell discontinuity along the junction surface between ingoing and outgoing solutions, 2) there are special cases where the shell vanishes and 3) these conclusions also apply to charged Vaidya (the original paper argued that there were no shells at the junctions). Along the way we note an apparent error in the standard classification of energy condition violations for Type II stress-energy tensors.

  4. Compressional plasma flows near magnetic null points

    Energy Technology Data Exchange (ETDEWEB)

    Bulanov, S.V.; Ol' shanetskii, M.A.

    1985-06-01

    Self-similar solutions of the MHD equations describing time-varying plasma flows near magnetic null points are analyzed. Various classes of particular solutions are constructed. Special attention is paid to compressional flows which involve the development of sharp maxima. The stability of the self-similar solutions is studied. Solutions describing the motion of a vortex in MHD are constructed. The possibility of producing current sheets in nonuniform magnetic configurations is demonstrated.

  5. Collapse and bounce of null fluids

    OpenAIRE

    Creelman, Bradley; Booth, Ivan

    2016-01-01

    Exact solutions describing the spherical collapse of null fluids can contain regions which violate the energy conditions. Physically the violations occur when the infalling matter continues to move inwards even when non-gravitational repulsive forces become stronger than gravity. In 1991 Ori proposed a resolution for these violations: spacetime surgery should be used to replace the energy condition violating region with an outgoing solution. The matter bounces. We revisit and implement this p...

  6. A Conformal Extension Theorem based on Null Conformal Geodesics

    CERN Document Server

    Lübbe, Christian

    2008-01-01

    In this article we describe the formulation of null geodesics as null conformal geodesics and their description in the tractor formalism. A conformal extension theorem through an isotropic singularity is proven by requiring the boundedness of the tractor curvature and its derivatives to sufficient order along a congruence of null conformal geodesic. This article extends earlier work by Tod and Luebbe.

  7. Morphological Uniformity and the Null Subject Parameter in Adult SLA.

    Science.gov (United States)

    Davies, William D.

    1996-01-01

    Focuses on the application of the Null Subject Parameter. Data reveals that some second-language learners exhibit knowledge that English is morphologically nonuniform yet still accept English null subject sentences. Findings disprove the Morphological Uniformity Hypothesis, indicating that any reformulation of the Null Subject Parameter must…

  8. Null controllability and the algebraic Riccati equation in Banach Spaces

    NARCIS (Netherlands)

    Van Neerven, J.M.A.M.

    2005-01-01

    By a recent result of Priola and Zabczyk, a null controllable linear system [y'(t) = Ay(t) + Bu(t)] in a Hilbert space E is null controllable with vanishing energy if and only if it is null controllable and the only positive self-adjoint solution of the associated algebraic Riccati equation [XA + A*

  9. PHASE CLOSURE NULLING: THEORY AND PRACTICE

    Directory of Open Access Journals (Sweden)

    A. Chelli

    2009-01-01

    Full Text Available We provide a complete theory of the phase closure of a binary system in which a small, feeble, and unresolved companion acts as a perturbing parameter on the spatial frequency spectrum of a dominant, bright, resolved source. We demonstrate that the in uence of the companion can be measured with precision by measuring the phase closure of the system near the nulls of the primary visibility function. In these regions of phase closure nulling, frequency intervals always exist where the phase closure signature of the companion is larger than any systematic error and can thus be measured. We show that this technique allows retrieval of many astrophysically relevant properties of faint and close companions such as ux, position, and in favorable cases, spectrum. As a proof of concept, using the AMBER/VLTI instrument with 3 auxiliary telescopes of 1.8 m and only 15 minutes of on-sky integration, we detected the ve magnitudes fainter companion of HD 59717 at only 3.5 stellar radii distance from the primary. This is one of the highest contrast detected by interferometry between a companion and its parent star. We conclude by a rapid study of the potentialities of phase closure nulling observations with current interferometers and explore the requirements for a new type of dedicated instrument.

  10. Magnetic Null Points in Kinetic Simulations of Space Plasmas

    Science.gov (United States)

    Olshevsky, Vyacheslav; Deca, Jan; Divin, Andrey; Peng, Ivy Bo; Markidis, Stefano; Innocenti, Maria Elena; Cazzola, Emanuele; Lapenta, Giovanni

    2016-03-01

    We present a systematic attempt to study magnetic null points and the associated magnetic energy conversion in kinetic particle-in-cell simulations of various plasma configurations. We address three-dimensional simulations performed with the semi-implicit kinetic electromagnetic code iPic3D in different setups: variations of a Harris current sheet, dipolar and quadrupolar magnetospheres interacting with the solar wind, and a relaxing turbulent configuration with multiple null points. Spiral nulls are more likely created in space plasmas: in all our simulations except lunar magnetic anomaly (LMA) and quadrupolar mini-magnetosphere the number of spiral nulls prevails over the number of radial nulls by a factor of 3-9. We show that often magnetic nulls do not indicate the regions of intensive energy dissipation. Energy dissipation events caused by topological bifurcations at radial nulls are rather rare and short-lived. The so-called X-lines formed by the radial nulls in the Harris current sheet and LMA simulations are rather stable and do not exhibit any energy dissipation. Energy dissipation is more powerful in the vicinity of spiral nulls enclosed by magnetic flux ropes with strong currents at their axes (their cross sections resemble 2D magnetic islands). These null lines reminiscent of Z-pinches efficiently dissipate magnetic energy due to secondary instabilities such as the two-stream or kinking instability, accompanied by changes in magnetic topology. Current enhancements accompanied by spiral nulls may signal magnetic energy conversion sites in the observational data.

  11. System and Method for Null-Lens Wavefront Sensing

    Science.gov (United States)

    Hill, Peter C. (Inventor); Thompson, Patrick L. (Inventor); Aronstein, David L. (Inventor); Bolcar, Matthew R. (Inventor); Smith, Jeffrey S. (Inventor)

    2015-01-01

    A method of measuring aberrations in a null-lens including assembly and alignment aberrations. The null-lens may be used for measuring aberrations in an aspheric optic with the null-lens. Light propagates from the aspheric optic location through the null-lens, while sweeping a detector through the null-lens focal plane. Image data being is collected at locations about said focal plane. Light is simulated propagating to the collection locations for each collected image. Null-lens aberrations may extracted, e.g., applying image-based wavefront-sensing to collected images and simulation results. The null-lens aberrations improve accuracy in measuring aspheric optic aberrations.

  12. Null Object模式研究%Research on Null Object Pattern

    Institute of Scientific and Technical Information of China (English)

    吴清寿

    2013-01-01

    在许多面向对象的程序设计语言中,对象引用可能为空.在调用任何方法之前这些引用需要被检测以确保它们不为空.频繁的检测会引起代码的重复和系统的不稳定.Null Object模式能够用来解决这一问题.本文阐述了Null Object模式及其实现方式,针对空目标的单一实例化策略,给出了改进措施.Null Object模式对去除重复检测和减少空引用异常有较明显的效果.

  13. A note on inextensible flows of partially and pseudo null curves in E_1^4

    OpenAIRE

    Yuzbasi, Zuhal Kucukarslan; Bektas, Mehmet

    2013-01-01

    In this paper, we study inextensible flows of partially null and pseudo null curves in E_1^4. We give neccessary and sufficent conditions for inextensible flows of partially null and pseudo null curves in E_1^4

  14. Causal Space-Times on a Null Lattice

    CERN Document Server

    Schaden, Martin

    2015-01-01

    I investigate a model of quantum gravity based on the first order Hilbert Palatini action with cosmological constant, discretized on a causal null-lattice with SL(2,C) structure group. The description is coordinate invariant and foliates in a causal and physically transparent manner. Lattice variables and observables are constructed. Conditions for a lattice configuration to describe a triangulated causal manifold are derived and encoded by a topological lattice theory. An equivariant BRST-construction is used to partially localize the SL(2,C) structure group of this model to the compact SU(2) of local spatial rotations. The latter in turn is completely localized using the spinors of this formulation. The integration measure of this completely localized model is derived from the SL(2,C)-invariant integration measure and is expressed in terms of SL(2,C)-invariant variables. An invariant regularization of the lattice integration measure that suppresses configurations with small local four-volumes is proposed. N...

  15. Reconnection experiments with 3D magnetic nulls

    Science.gov (United States)

    Vrublevskis, A.; Egedal, J.; Le, A.; Montag, P.

    2011-10-01

    Three-dimensional effects have been crucial in explaining experiments at the Versatile Toroidal Facility (VTF) even in nominal axisymmetric plasmas with a non-vanishing toroidal field. In general, depending on the topological and geometric structure of the magnetic field, a rich collection of magnetic reconnection scenarios is possible in three dimensions. The new adjustable set of coils in VTF allows exploring reconnection in 2D and 3D geometries including configurations with magnetic null points. We present results of a numerical and experimental investigation of magnetic field topologies attainable in VTF. This work was supported by NSF CAREER Award 0844620.

  16. Polarization Null Characteristics of Simple Targets

    Science.gov (United States)

    1983-01-01

    O( - O, as desired. -12- We now want to find a canonical form of A under a unitary transformation. In Appendix 8.4, it is shown that A can be...P X 4 cos4- Degenerate case y =0,0- t;x’) s i2 ; --- 2v < -tx’ Vr tje -) *cos Degenerate case y - ,10-j•); tM ~cos1 );S cols 2 Ti ,f<’t1 , sin ;s . i0...the case for a typical radar target. We then expect the shape and centroid of the loci of Figure 5 to change as the null moves .around on the locus

  17. Recent developments with the visible nulling coronagraph

    Science.gov (United States)

    Hicks, Brian A.; Lyon, Richard G.; Bolcar, Matthew R.; Clampin, Mark; Petrone, Peter; Helmbrecht, Michael A.; Howard, Joseph M.; Miller, Ian J.

    2016-08-01

    A wide array of general astrophysics studies including detecting and characterizing habitable exoplanets could be enabled by a future large segmented telescope with sensitivity in the UV, optical, and infrared bands. When paired with a starshade or coronagraph, such an observatory could enable direct imaging and detailed spectroscopic observations of nearby Earth-like habitable zone planets. Over the past several years, a laboratory-based Visible Nulling Coronagraph (VNC) has evolved to reach requisite contrasts over a 1 nm bandwidth at narrow source angle separation using a segmented deformable mirror in one arm of a Mach-Zehnder layout. More recent efforts targeted broadband performance following the addition of two sets of half-wave Fresnel rhomb achromatic phase shifters (APS) with the goal of reaching 10-9 contrast, at a separation of 2λ/D, using a 40 nm (6%) bandwidth single mode fiber source. Here we present updates on the VNC broadband nulling effort, including approaches to addressing system contrast limitations.

  18. Averaged null energy condition from causality

    Science.gov (United States)

    Hartman, Thomas; Kundu, Sandipan; Tajdini, Amirhossein

    2017-07-01

    Unitary, Lorentz-invariant quantum field theories in flat spacetime obey mi-crocausality: commutators vanish at spacelike separation. For interacting theories in more than two dimensions, we show that this implies that the averaged null energy, ∫ duT uu , must be non-negative. This non-local operator appears in the operator product expansion of local operators in the lightcone limit, and therefore contributes to n-point functions. We derive a sum rule that isolates this contribution and is manifestly positive. The argument also applies to certain higher spin operators other than the stress tensor, generating an infinite family of new constraints of the form ∫ duX uuu··· u ≥ 0. These lead to new inequalities for the coupling constants of spinning operators in conformal field theory, which include as special cases (but are generally stronger than) the existing constraints from the lightcone bootstrap, deep inelastic scattering, conformal collider methods, and relative entropy. We also comment on the relation to the recent derivation of the averaged null energy condition from relative entropy, and suggest a more general connection between causality and information-theoretic inequalities in QFT.

  19. On the null origin of the ambitwistor string

    Science.gov (United States)

    Casali, Eduardo; Tourkine, Piotr

    2016-11-01

    In this paper we present the null string origin of the ambitwistor string. Classically, the null string is the tensionless limit of string theory, and so too is the ambitwistor string. Both have as constraint algebra the Galilean Conformal Algebra in two dimensions. But something interesting happens in the quantum theory since there is an ambiguity in quantizing the null string. We show that, given a particular choice of quantization scheme and a particular gauge, the null string coincides with the ambitwistor string both classically and quantum mechanically. We also show that the same holds for the spinning versions of the null string and ambitwistor string. With these results we clarify the relationship between the ambitwistor string, the null string, the usual string and the Hohm-Siegel-Zwiebach theory.

  20. Off-Axis Nulling Transfer Function Measurement: A First Assessment

    Science.gov (United States)

    Vedova, G. Dalla; Menut, J.-L.; Millour, F.; Petrov, R.; Cassaing, F.; Danchi, W. C.; Jacquinod, S.; Lhome, E.; Lopez, B.; Lozi, J.; hide

    2013-01-01

    We want to study a polychromatic inverse problem method with nulling interferometers to obtain information on the structures of the exozodiacal light. For this reason, during the first semester of 2013, thanks to the support of the consortium PERSEE, we launched a campaign of laboratory measurements with the nulling interferometric test bench PERSEE, operating with 9 spectral channels between J and K bands. Our objective is to characterise the transfer function, i.e. the map of the null as a function of wavelength for an off-axis source, the null being optimised on the central source or on the source photocenter. We were able to reach on-axis null depths better than 10(exp -4). This work is part of a broader project aiming at creating a simulator of a nulling interferometer in which typical noises of a real instrument are introduced. We present here our first results.

  1. Particle acceleration near magnetic nulls using MMS data

    Science.gov (United States)

    Eriksson, Elin; Vaivads, Andris; Khotyaintsev, Yuri; Graham, Daniel; Markidis, Stefano; Peng, Ivy Bo; André, Mats; Burch, James; Lindqvist, Per-Arne; Ergun, Robert; Torbert, Roy; Magnes, Werner; Russell, Christopher; Giles, Barbara; Pollock, Craig

    2016-04-01

    Regions with vanishing magnetic field, also referred to as magnetic nulls, are of high interest in plasma physics. Near magnetic nulls particles become unmagnetized and can by interacting with electric fields be accelerated up to high energies. Magnetic nulls have been observed and studied before using using Cluster data with different methods. Magnetic nulls found by Cluster have been obtained with spacecraft separation comparable to ion scales and particle instrumentation is not sufficient to resolve in detail physical processes of particle acceleration around the null. Now we use the MMS (Magnetospheric Multiscale) data to study these processes in detail. The MMS separation is well below the ion scale and data from particle instruments has sufficient resolution during burst mode to resolve these processes for our events. We study nulls in detail during phase 1a of the MMS mission. Burst data during this phase are mainly from the magnetopause, but some intervals cover the magnetosheath, bowshock, and solar wind. We particularly focus on magnetic nulls associated with strong currents, which can potentially be associated with the electron diffusion region of magnetic reconnection. There we also expect particle acceleration to occur. A preliminary study has already identified several nulls of high interest in the burst data. We present a detailed study of these nulls.

  2. Reconnection experiments including 3D magnetic nulls

    Science.gov (United States)

    Le, A.; Egedal, J.; Vrublevskis, A.

    2010-11-01

    A rich collection of magnetic reconnection scenarios is possible in three dimensions depending on the topological and geometric structure of the magnetic field [1]. In recent experiments at the Versatile Toroidal Facility (VTF) three-dimensional effects were essential even in nearly axisymmetric plasmas with a non-vanishing toroidal field [2]. To explore reconnection in 3D geometries including magnetic null points, a new adjustable set of coils will be installed in the vacuum chamber of VTF. The range of vacuum magnetic field topologies attainable in VTF will be explored numerically. Plasma reconnection experiments will be run in these configurations, and measurements will be presented if available. [4pt] [1] CE Parnell, et al., (2009) ``Three-Dimensional Magnetic Reconnection, in Magnetic Coupling between the Interior and the Atmosphere of the Sun,'' eds. S.S. Hasan and R.J. Rutten, Springer-Verlag, Heidelberg, Berlin. [0ex] [2] Katz, N. et al., (2010) Phys. Rev. Lett. 104, 255004.

  3. Wormholes minimally violating the null energy condition

    CERN Document Server

    Bouhmadi-Lopez, Mariam; Martin-Moruno, Prado

    2014-01-01

    We consider novel wormhole solutions supported by a matter content that minimally violates the null energy condition. More specifically, we consider an equation of state in which the sum of the energy density and radial pressure is proportional to a constant with a value smaller than that of the inverse area characterising the system, i.e., the area of the wormhole mouth. This approach is motivated by a recently proposed cosmological event, denoted "the little sibling of the big rip", where the Hubble rate and the scale factor blow up but the cosmic derivative of the Hubble rate does not [1]. By using the cut-and-paste approach, we match interior spherically symmetric wormhole solutions to an exterior Schwarzschild geometry, and analyze the stability of the thin-shell to linearized spherically symmetric perturbations around static solutions, by choosing suitable properties for the exotic material residing on the junction interface radius. Furthermore, we also consider an inhomogeneous generalisation of the eq...

  4. Null fluid collapse in brane world models

    CERN Document Server

    Harko, Tiberiu

    2013-01-01

    The brane world description of our universe entails a large extra dimension and a fundamental scale of gravity that may be lower than the Planck scale by several orders of magnitude. An interesting consequence of this scenario occurs in the nature of spherically-symmetric vacuum solutions to the brane gravitational field equations, which often have properties quite distinct from the standard black hole solutions of general relativity. In this paper, the spherically-symmetric collapse on the brane world of four types of null fluid, governed by the barotropic, polytropic, strange quark "bag" model and Hagedorn equations of state, is investigated. In each case, we solve the approximate gravitational field equations, obtained in the high density limit, determine the equation which governs the formation of apparent horizons and investigate the conditions for the formation of naked singularities. Though, naively, one would expect the increased effective energy density on the brane to favor the formation of black ho...

  5. Averaged Null Energy Condition from Causality

    CERN Document Server

    Hartman, Thomas; Tajdini, Amirhossein

    2016-01-01

    Unitary, Lorentz-invariant quantum field theories in flat spacetime obey microcausality: commutators vanish at spacelike separation. For interacting theories in more than two dimensions, we show that this implies that the averaged null energy, $\\int du T_{uu}$, must be positive. This non-local operator appears in the operator product expansion of local operators in the lightcone limit, and therefore contributes to $n$-point functions. We derive a sum rule that isolates this contribution and is manifestly positive. The argument also applies to certain higher spin operators other than the stress tensor, generating an infinite family of new constraints of the form $\\int du X_{uuu\\cdots u} \\geq 0$. These lead to new inequalities for the coupling constants of spinning operators in conformal field theory, which include as special cases (but are generally stronger than) the existing constraints from the lightcone bootstrap, deep inelastic scattering, conformal collider methods, and relative entropy. We also comment ...

  6. String spectra near some null cosmological singularities

    CERN Document Server

    Madhu, Kallingalthodi

    2009-01-01

    We construct cosmological spacetimes with null Kasner-like singularities as purely gravitational solutions with no other background fields turned on. These can be recast as anisotropic plane-wave spacetimes by coordinate transformations. We analyse string quantization to find the spectrum of string modes in these backgrounds. The classical string modes can be solved for exactly in these time-dependent backgrounds, which enables a detailed study of the near singularity string spectrum, (time-dependent) oscillator masses and wavefunctions. We find that for low lying string modes(finite oscillation number), the classical near-singularity string mode functions are non-divergent for various families of singularities. Furthermore, for any infinitesimal regularization of the vicinity of the singularity, we find a tower of string modes of ultra-high oscillation number which propagate essentially freely in the background. The resulting picture suggests that string interactions are non-negligible near the singularity.

  7. Dynamics of a probe null string in the gravitational field of a closed null string radially collapsing in the plane

    Science.gov (United States)

    Lelyakov, A. P.; Karpenko, A. S.

    2017-01-01

    We consider the dynamics of a probe null string in the gravitational field of a closed ( "thick") null string radially collapsing in a plane. Analysis of the obtained solutions suggests that there might exist several properties of a null-string gas interesting from the cosmological standpoint, such as acceleration of expansion or contraction, a granular structure of the gas, the emergence of stable polarized states, and a domain structure.

  8. MAGNETIC NULL POINTS IN KINETIC SIMULATIONS OF SPACE PLASMAS

    Energy Technology Data Exchange (ETDEWEB)

    Olshevsky, Vyacheslav; Innocenti, Maria Elena; Cazzola, Emanuele; Lapenta, Giovanni [Centre for Mathematical Plasma Astrophysics (CmPA), KU Leuven (Belgium); Deca, Jan [Laboratory for Atmospheric and Space Physics (LASP), University of Colorado Boulder, Boulder, CO (United States); Divin, Andrey [St. Petersburg State University, St. Petersburg (Russian Federation); Peng, Ivy Bo; Markidis, Stefano, E-mail: sya@mao.kiev.ua [High Performance Computing and Visualization (HPCViz), KTH Royal Institute of Technology, Stockholm (Sweden)

    2016-03-01

    We present a systematic attempt to study magnetic null points and the associated magnetic energy conversion in kinetic particle-in-cell simulations of various plasma configurations. We address three-dimensional simulations performed with the semi-implicit kinetic electromagnetic code iPic3D in different setups: variations of a Harris current sheet, dipolar and quadrupolar magnetospheres interacting with the solar wind, and a relaxing turbulent configuration with multiple null points. Spiral nulls are more likely created in space plasmas: in all our simulations except lunar magnetic anomaly (LMA) and quadrupolar mini-magnetosphere the number of spiral nulls prevails over the number of radial nulls by a factor of 3–9. We show that often magnetic nulls do not indicate the regions of intensive energy dissipation. Energy dissipation events caused by topological bifurcations at radial nulls are rather rare and short-lived. The so-called X-lines formed by the radial nulls in the Harris current sheet and LMA simulations are rather stable and do not exhibit any energy dissipation. Energy dissipation is more powerful in the vicinity of spiral nulls enclosed by magnetic flux ropes with strong currents at their axes (their cross sections resemble 2D magnetic islands). These null lines reminiscent of Z-pinches efficiently dissipate magnetic energy due to secondary instabilities such as the two-stream or kinking instability, accompanied by changes in magnetic topology. Current enhancements accompanied by spiral nulls may signal magnetic energy conversion sites in the observational data.

  9. Intimal hyperplasia in loop-injured carotid arteries is attenuated in transglutaminase 2-null mice.

    Science.gov (United States)

    Min, Seung-Kee; Min, Sang-Il; Jeong, Eui Man; Cho, Sung-Yup; Ha, Jongwon; Kim, Sang Joon; Kim, In-Gyu

    2014-03-01

    Arterial restenosis frequently develops after open or endovascular surgery due to intimal hyperplasia. Since tissue transglutaminase (TG2) is known to involve in fibrosis, wound healing, and extracellular matrix remodeling, we examined the role of TG2 in the process of intimal hyperplasia using TG2-null mice. The neointimal formation was compared between TG2-null and wild-type (C57BL/6) mice by two different injury models; carotid ligation and carotid loop injury. In ligation model, there was no difference in intimal thickness between two groups. In loop injury model, intimal hyperplasia developed in both groups and the intimal/medial area ratio was significantly reduced in TG2-null mice (P = 0.007). TG2 was intensely stained in neointimal cells in 2 weeks. In situ activity of TG2 in the injured arteries steadily increased until 4 weeks compared to uninjured arteries. Taken together, intimal hyperplasia was significantly reduced in TG2-null mice, indicating that TG2 has an important role in the development of intimal hyperplasia. This suggests that TG2 may be a novel target to prevent the arterial restenosis after vascular surgery.

  10. ENERGY DISSIPATION IN MAGNETIC NULL POINTS AT KINETIC SCALES

    Energy Technology Data Exchange (ETDEWEB)

    Olshevsky, Vyacheslav; Lapenta, Giovanni [Centre for Mathematical Plasma Astrophysics (CmPA), KU Leuven (Belgium); Divin, Andrey [Department of Physics, St. Petersburg State University (Russian Federation); Eriksson, Elin [Swedish Institute of Space Physics, Uppsala Division, Uppsala (Sweden); Markidis, Stefano, E-mail: sya@mao.kiev.ua [High Performance Computing and Visualization (HPCViz), KTH Royal Institute of Technology, Stockholm (Sweden)

    2015-07-10

    We use kinetic particle-in-cell and MHD simulations supported by an observational data set to investigate magnetic reconnection in clusters of null points in space plasma. The magnetic configuration under investigation is driven by fast adiabatic flux rope compression that dissipates almost half of the initial magnetic field energy. In this phase powerful currents are excited producing secondary instabilities, and the system is brought into a state of “intermittent turbulence” within a few ion gyro-periods. Reconnection events are distributed all over the simulation domain and energy dissipation is rather volume-filling. Numerous spiral null points interconnected via their spines form null lines embedded into magnetic flux ropes; null point pairs demonstrate the signatures of torsional spine reconnection. However, energy dissipation mainly happens in the shear layers formed by adjacent flux ropes with oppositely directed currents. In these regions radial null pairs are spontaneously emerging and vanishing, associated with electron streams and small-scale current sheets. The number of spiral nulls in the simulation outweighs the number of radial nulls by a factor of 5–10, in accordance with Cluster observations in the Earth's magnetosheath. Twisted magnetic fields with embedded spiral null points might indicate the regions of major energy dissipation for future space missions such as the Magnetospheric Multiscale Mission.

  11. Energy Dissipation in Magnetic Null Points at Kinetic Scales

    Science.gov (United States)

    Olshevsky, Vyacheslav; Divin, Andrey; Eriksson, Elin; Markidis, Stefano; Lapenta, Giovanni

    2015-07-01

    We use kinetic particle-in-cell and MHD simulations supported by an observational data set to investigate magnetic reconnection in clusters of null points in space plasma. The magnetic configuration under investigation is driven by fast adiabatic flux rope compression that dissipates almost half of the initial magnetic field energy. In this phase powerful currents are excited producing secondary instabilities, and the system is brought into a state of “intermittent turbulence” within a few ion gyro-periods. Reconnection events are distributed all over the simulation domain and energy dissipation is rather volume-filling. Numerous spiral null points interconnected via their spines form null lines embedded into magnetic flux ropes; null point pairs demonstrate the signatures of torsional spine reconnection. However, energy dissipation mainly happens in the shear layers formed by adjacent flux ropes with oppositely directed currents. In these regions radial null pairs are spontaneously emerging and vanishing, associated with electron streams and small-scale current sheets. The number of spiral nulls in the simulation outweighs the number of radial nulls by a factor of 5-10, in accordance with Cluster observations in the Earth's magnetosheath. Twisted magnetic fields with embedded spiral null points might indicate the regions of major energy dissipation for future space missions such as the Magnetospheric Multiscale Mission.

  12. Magnetic null points in kinetic simulations of space plasmas

    CERN Document Server

    Olshevsky, Vyacheslav; Divin, Andrey; Peng, Ivy Bo; Markidis, Stefano; Innocenti, Maria Elena; Cazzola, Emanuele; Lapenta, Giovanni

    2015-01-01

    We present a systematic attempt to study magnetic null points and the associated magnetic energy conversion in kinetic Particle-in-Cell simulations of various plasma configurations. We address three-dimensional simulations performed with the semi-implicit kinetic electromagnetic code iPic3D in different setups: variations of a Harris current sheet, dipolar and quadrupolar magnetospheres interacting with the solar wind; and a relaxing turbulent configuration with multiple null points. Spiral nulls are more likely created in space plasmas: in all our simulations except lunar magnetic anomaly and quadrupolar mini-magnetosphere the number of spiral nulls prevails over the number of radial nulls by a factor of 3-9. We show that often magnetic nulls do not indicate the regions of intensive energy dissipation. Energy dissipation events caused by topological bifurcations at radial nulls are rather rare and short-lived. The so-called X-lines formed by the radial nulls in the Harris current sheet and lunar magnetic ano...

  13. Gravity Degrees of Freedom on a Null Surface

    CERN Document Server

    Hopfmüller, Florian

    2016-01-01

    A canonical analysis for general relativity is performed on a null surface without fixing the diffeomorphism gauge, and the canonical pairs of configuration and momentum variables are derived. Next to the well-known spin-2 pair, also spin-1 and spin-0 pairs are identified. The boundary action for a null boundary segment of spacetime is obtained, including terms on codimension two corners.

  14. The Meaning of Null in Databases and Programming Languages

    OpenAIRE

    Baclawski, Kenneth

    2016-01-01

    The meaning of null in relational databases is a major source of confusion not only among database users but also among database textbook writers. The purpose of this article is to examine what database nulls could mean and to make some modest suggestions about how to reduce the confusion.

  15. Flow of geometries and instantons on the null orbifold

    Energy Technology Data Exchange (ETDEWEB)

    Berkooz, Micha [Weizmann Institute of Science, Rehovot 76100 (Israel); Komargodski, Zohar [Weizmann Institute of Science, Rehovot 76100 (Israel); Reichmann, Dori [Weizmann Institute of Science, Rehovot 76100 (Israel); Shpitalnik, Vadim [Weizmann Institute of Science, Rehovot 76100 (Israel)

    2005-12-15

    We study condensation of twisted sector states in the null orbifold geometry. As the singularity is time-dependent, we probe it using D-Instantons. We present evidence that the null-orbifold flows to the Z{sub N} orbifold. We also comment on the subtleties of quantizing the closed superstring in this background.

  16. Exact null controllability of degenerate evolution equations with scalar control

    Energy Technology Data Exchange (ETDEWEB)

    Fedorov, Vladimir E; Shklyar, Benzion

    2012-12-31

    Necessary and sufficient conditions for the exact null controllability of a degenerate linear evolution equation with scalar control are obtained. These general results are used to examine the exact null controllability of the Dzektser equation in the theory of seepage. Bibliography: 13 titles.

  17. Moving beyond traditional null hypothesis testing: evaluating expectations directly

    NARCIS (Netherlands)

    van de Schoot, R.; Hoijtink, H.J.A.; Romeijn, J.W.

    2011-01-01

    This mini-review illustrates that testing the traditional null hypothesis is not always the appropriate strategy. Half in jest, we discuss Aristotle's scientific investigations into the shape of the earth in the context of evaluating the traditional null hypothesis. We conclude that Aristotle was ac

  18. Logarithmic corrections to gravitational entropy and the null energy condition

    Science.gov (United States)

    Parikh, Maulik; Svesko, Andrew

    2016-10-01

    Using a relation between the thermodynamics of local horizons and the null energy condition, we consider the effects of quantum corrections to the gravitational entropy. In particular, we find that the geometric form of the null energy condition is not affected by the inclusion of logarithmic corrections to the Bekenstein-Hawking entropy.

  19. Logarithmic corrections to gravitational entropy and the null energy condition

    Directory of Open Access Journals (Sweden)

    Maulik Parikh

    2016-10-01

    Full Text Available Using a relation between the thermodynamics of local horizons and the null energy condition, we consider the effects of quantum corrections to the gravitational entropy. In particular, we find that the geometric form of the null energy condition is not affected by the inclusion of logarithmic corrections to the Bekenstein–Hawking entropy.

  20. Einstein equations in the null quasi-spherical gauge

    CERN Document Server

    Bartnik, R A

    1997-01-01

    The structure of the full Einstein equations in a coordinate gauge based on expanding null hypersurfaces foliated by metric 2-spheres is explored. The simple form of the resulting equations has many applications -- in the present paper we describe the structure of timelike boundary conditions; the matching problem across null hypersurfaces; and the propagation of gravitational shocks.

  1. Visual and Plastic Arts in Teaching Literacy: Null Curricula?

    Science.gov (United States)

    Wakeland, Robin Gay

    2010-01-01

    Visual and plastic arts in contemporary literacy instruction equal null curricula. Studies show that painting and sculpture facilitate teaching reading and writing (literacy), yet such pedagogy has not been formally adopted into USA curriculum. An example of null curriculum can be found in late 19th - early 20th century education the USA…

  2. DARWIN nulling interferometer breadboard II: design and manufacturing

    NARCIS (Netherlands)

    Vink, H.J.P.; Doelman, N.J.; Flatscher, R.; Sodnik, Z.

    2003-01-01

    Nulling interferometry is a direct method to detect earth-like planets. To determine whether a planet is earth-like spectrometry can be performed which requires a broadband optical input signal from the planet. Nulling interferometry should decrease the broadband (λ ≈ 6-18μm) star signal by about a

  3. A new dynamic null model for phylogenetic community structure

    NARCIS (Netherlands)

    Pigot, Alex L; Etienne, Rampal S

    2015-01-01

    Phylogenies are increasingly applied to identify the mechanisms structuring ecological communities but progress has been hindered by a reliance on statistical null models that ignore the historical process of community assembly. Here, we address this, and develop a dynamic null model of assembly by

  4. Glutathione S-transferases gene polymorphisms and risk of male idiopathic infertility: a systematic review and meta-analysis.

    Science.gov (United States)

    Li, Xin; Pan, Jinhong; Liu, Qigui; Xiong, Enqing; Chen, Zhiwen; Zhou, Zhansong; Su, Yongping; Lu, Gensheng

    2013-03-01

    The Glutathione S-transferases (GSTs) polymorphisms have been implicated in susceptibility to male idiopathic infertility, but study results are still controversial. To investigate the genetic associations between GSTs polymorphisms and risk of male idiopathic infertility, a systematic review and meta-analysis were performed. Meta-analysis was performed by pooling odds ratio (OR) with its corresponding 95 % confidence interval (95 % CI) form studies in electronic databases up to March 16, 2012. Glutathione S-transferase M 1 (GSTM1) null genotype, Glutathione S-transferase T 1 (GSTT1) null genotype, and dual null genotype of GSTM1/GSTT1 were analyzed independently. 14 eligible studies with a total of 1,845 idiopathic infertility males and 1,729 controls were included. There were 13 studies on GSTM1 polymorphism, 10 ones on GSTT1 polymorphism and 5 ones on GSTM1-GSTT1 interaction analysis. Meta-analyses of total relevant studies showed GSTM1 null genotype was significantly associated with an increased risk of male idiopathic infertility (OR = 1.40, 95 % CI 1.07-1.84, P OR = 0.015). The GSTM1-GSTT1 interaction analysis showed dual null genotype of GSTM1/GSTT1 was also significantly associated with increased risk of male idiopathic infertility (OR = 1.85, 95 % CI 1.07-3.21, P OR = 0.028). Subgroup analyses by ethnicity showed the associations above were still statistically significant in Caucasians (For GSTM1, OR = 1.51, 95 % CI 1.11-2.05, P OR = 0.009; For GSTM1/GSTT1, OR = 2.10, 95 % CI 1.51-2.91, P OR < 0.001). This meta-analysis suggests GSTM1 null genotype contributes to increased risk of male idiopathic infertility in Caucasians, and males with dual null genotype of GSTM1/GSTT1 are particularly susceptible to developing idiopathic infertility.

  5. Reconnection experiments with 3D magnetic nulls in different topologies

    Science.gov (United States)

    Vrublevskis, A.; Egedal, J.; Le, A.

    2012-10-01

    Magnetic reconnection has been predominantly investigated in two dimensions. However, depending on the topology and geometry of the magnetic field, a rich collection of magnetic reconnection scenarios is possible in 3D including reconnection at magnetic nulls. At the Versatile Toroidal Facility (VTF) we have implemented a new magnetic geometry with a pair of 3D null points in the background toroidal field. We form a flux rope along the background field and observe it to rapidly restructure and rewire as the nulls develop. We can adjust the topology of the configuration from one where a field line connects the nulls to one where the nulls are no longer linked. A suit of diagnostics will be deployed and results presented for how the topology affects the dynamics of the flux rope.

  6. Energy dissipation in magnetic null points at kinetic scales

    CERN Document Server

    Olshevsky, Vyacheslav; Eriksson, Elin; Markidis, Stefano; Lapenta, Giovanni

    2015-01-01

    We use kinetic particle-in-cell and magnetohydrodynamic simulations supported by an observational dataset to investigate magnetic reconnection in clusters of null points in space plasma. The magnetic configuration under investigation is driven by fast adiabatic flux rope compression that dissipates almost half of the initial magnetic field energy. In this phase powerful currents are excited producing secondary instabilities, and the system is brought into a state of `intermittent turbulence' within a few ion gyro-periods. Reconnection events are distributed all over the simulation domain and energy dissipation is rather volume-filling. Numerous spiral null points interconnected via their spines form null lines embedded into magnetic flux ropes; null point pairs demonstrate the signatures of torsional spine reconnection. However, energy dissipation mainly happens in the shear layers formed by adjacent flux ropes with oppositely directed currents. In these regions radial null pairs are spontaneously emerging an...

  7. Sidelobe Suppression with Null Steering by Independent Weight Control

    Directory of Open Access Journals (Sweden)

    Zafar-Ullah Khan

    2015-01-01

    Full Text Available A uniform linear array of n antenna elements can steer up to n-1 nulls. In situations where less than n-1 nulls are required to be steered, the existing algorithms have no criterion to utilize the remaining weights for sidelobe suppression. This work combines sidelobe suppression capability with null steering by independent weight control. For this purpose, the array factor is transformed as the product of two polynomials. One of the polynomials is used for null steering by independent weight control, while the second one is for sidelobe suppression whose coefficients or weights are determined by using convex optimization. Finally, a new structure is proposed to incorporate the product of two polynomials such that sidelobe suppression weights are decoupled from those of null steering weights. Simulation results validate the effectiveness of the proposed scheme.

  8. Estimating Relatedness in the Presence of Null Alleles.

    Science.gov (United States)

    Huang, Kang; Ritland, Kermit; Dunn, Derek W; Qi, Xiaoguang; Guo, Songtao; Li, Baoguo

    2016-01-01

    Studies of genetics and ecology often require estimates of relatedness coefficients based on genetic marker data. However, with the presence of null alleles, an observed genotype can represent one of several possible true genotypes. This results in biased estimates of relatedness. As the numbers of marker loci are often limited, loci with null alleles cannot be abandoned without substantial loss of statistical power. Here, we show how loci with null alleles can be incorporated into six estimators of relatedness (two novel). We evaluate the performance of various estimators before and after correction for null alleles. If the frequency of a null allele is 0.5, the potency of estimation is too low and such a locus should be excluded. We make available a software package entitled PolyRelatedness v1.6, which enables researchers to optimize these estimators to best fit a particular data set.

  9. Null hypersurfaces in generalized Robertson-Walker spacetimes

    Science.gov (United States)

    Navarro, Matias; Palmas, Oscar; Solis, Didier A.

    2016-08-01

    We study the geometry of null hypersurfaces M in generalized Robertson-Walker spacetimes. First we characterize such null hypersurfaces as graphs of generalized eikonal functions over the fiber and use this characterization to show that such hypersurfaces are parallel if and only if their fibers are also parallel. We further use this technique to construct several examples of null hypersurfaces in both de Sitter and anti de Sitter spaces. Then we characterize all the totally umbilical null hypersurfaces M in a Lorentzian space form (viewed as a quadric in a semi-Euclidean ambient space) as intersections of the space form with a hyperplane. Finally we study the totally umbilical spacelike hypersurfaces of null hypersurfaces in space forms and characterize them as planar sections of M.

  10. Null Models for Everyone: A Two-Step Approach to Teaching Null Model Analysis of Biological Community Structure

    Science.gov (United States)

    McCabe, Declan J.; Knight, Evelyn J.

    2016-01-01

    Since being introduced by Connor and Simberloff in response to Diamond's assembly rules, null model analysis has been a controversial tool in community ecology. Despite being commonly used in the primary literature, null model analysis has not featured prominently in general textbooks. Complexity of approaches along with difficulty in interpreting…

  11. 'Null method' determination of drug biophase concentration.

    Science.gov (United States)

    Tallarida, Ronald J; Lamarre, Neil; Raffa, Robert B

    2012-03-01

    PK/PD modeling is enhanced by improvements in the accuracy of its metrics. For PK/PD modeling of drugs and biologics that interact with enzymes or receptors, the equilibrium constant of the interaction can provide critical insight. Methodologies such as radioliogand binding and isolated tissue preparations can provide estimates of the equilibrium constants (as the dissociation constant, K value) for drugs and endogenous ligands that interact with specific enzymes and receptors. However, an impediment to further precision for PK/PD modeling is that it remains a problem to convert the concentration of drug in bulk solution (A) into an estimate of receptor occupation, since A is not necessarily the concentration (C) of drug in the biophase that yields fractional binding from the law of mass action, viz., C/(C + K). In most experimental studies A is much larger than K, so the use of administered instead of biophase concentration gives fractional occupancies very close to unity. We here provide a simple way to obtain an estimate of the factor that converts the total drug concentration into the biophase concentration in isolated tissue preparation. Our approach is an extension of the now classic 'null method' introduced and applied by Furchgott to determination of drug-receptor dissociation constants.

  12. A null model for Pearson coexpression networks.

    Science.gov (United States)

    Gobbi, Andrea; Jurman, Giuseppe

    2015-01-01

    Gene coexpression networks inferred by correlation from high-throughput profiling such as microarray data represent simple but effective structures for discovering and interpreting linear gene relationships. In recent years, several approaches have been proposed to tackle the problem of deciding when the resulting correlation values are statistically significant. This is most crucial when the number of samples is small, yielding a non-negligible chance that even high correlation values are due to random effects. Here we introduce a novel hard thresholding solution based on the assumption that a coexpression network inferred by randomly generated data is expected to be empty. The threshold is theoretically derived by means of an analytic approach and, as a deterministic independent null model, it depends only on the dimensions of the starting data matrix, with assumptions on the skewness of the data distribution compatible with the structure of gene expression levels data. We show, on synthetic and array datasets, that the proposed threshold is effective in eliminating all false positive links, with an offsetting cost in terms of false negative detected edges.

  13. Wormholes minimally violating the null energy condition

    Science.gov (United States)

    Bouhmadi-López, Mariam; Lobo, Francisco S. N.; Martín-Moruno, Prado

    2014-11-01

    We consider novel wormhole solutions supported by a matter content that minimally violates the null energy condition. More specifically, we consider an equation of state in which the sum of the energy density and radial pressure is proportional to a constant with a value smaller than that of the inverse area characterising the system, i.e., the area of the wormhole mouth. This approach is motivated by a recently proposed cosmological event, denoted "the little sibling of the big rip", where the Hubble rate and the scale factor blow up but the cosmic derivative of the Hubble rate does not [1]. By using the cut-and-paste approach, we match interior spherically symmetric wormhole solutions to an exterior Schwarzschild geometry, and analyse the stability of the thin-shell to linearized spherically symmetric perturbations around static solutions, by choosing suitable properties for the exotic material residing on the junction interface radius. Furthermore, we also consider an inhomogeneous generalization of the equation of state considered above and analyse the respective stability regions. In particular, we obtain a specific wormhole solution with an asymptotic behaviour corresponding to a global monopole.

  14. A null model for Pearson coexpression networks.

    Directory of Open Access Journals (Sweden)

    Andrea Gobbi

    Full Text Available Gene coexpression networks inferred by correlation from high-throughput profiling such as microarray data represent simple but effective structures for discovering and interpreting linear gene relationships. In recent years, several approaches have been proposed to tackle the problem of deciding when the resulting correlation values are statistically significant. This is most crucial when the number of samples is small, yielding a non-negligible chance that even high correlation values are due to random effects. Here we introduce a novel hard thresholding solution based on the assumption that a coexpression network inferred by randomly generated data is expected to be empty. The threshold is theoretically derived by means of an analytic approach and, as a deterministic independent null model, it depends only on the dimensions of the starting data matrix, with assumptions on the skewness of the data distribution compatible with the structure of gene expression levels data. We show, on synthetic and array datasets, that the proposed threshold is effective in eliminating all false positive links, with an offsetting cost in terms of false negative detected edges.

  15. Wormholes minimally violating the null energy condition

    Energy Technology Data Exchange (ETDEWEB)

    Bouhmadi-López, Mariam [Departamento de Física, Universidade da Beira Interior, 6200 Covilhã (Portugal); Lobo, Francisco S N; Martín-Moruno, Prado, E-mail: mariam.bouhmadi@ehu.es, E-mail: fslobo@fc.ul.pt, E-mail: pmmoruno@fc.ul.pt [Centro de Astronomia e Astrofísica da Universidade de Lisboa, Campo Grande, Edifício C8, 1749-016 Lisboa (Portugal)

    2014-11-01

    We consider novel wormhole solutions supported by a matter content that minimally violates the null energy condition. More specifically, we consider an equation of state in which the sum of the energy density and radial pressure is proportional to a constant with a value smaller than that of the inverse area characterising the system, i.e., the area of the wormhole mouth. This approach is motivated by a recently proposed cosmological event, denoted {sup t}he little sibling of the big rip{sup ,} where the Hubble rate and the scale factor blow up but the cosmic derivative of the Hubble rate does not [1]. By using the cut-and-paste approach, we match interior spherically symmetric wormhole solutions to an exterior Schwarzschild geometry, and analyse the stability of the thin-shell to linearized spherically symmetric perturbations around static solutions, by choosing suitable properties for the exotic material residing on the junction interface radius. Furthermore, we also consider an inhomogeneous generalization of the equation of state considered above and analyse the respective stability regions. In particular, we obtain a specific wormhole solution with an asymptotic behaviour corresponding to a global monopole.

  16. Null fluid collapse in brane world models

    Science.gov (United States)

    Harko, Tiberiu; Lake, Matthew J.

    2014-03-01

    The brane world description of our Universe entails a large extra dimension and a fundamental scale of gravity that may be lower than the Planck scale by several orders of magnitude. An interesting consequence of this scenario occurs in the nature of spherically symmetric vacuum solutions to the brane gravitational field equations, which often have properties quite distinct from the standard black hole solutions of general relativity. In this paper, the spherically symmetric collapse on the brane world of four types of null fluid, governed by the barotropic, polytropic, strange quark "bag" model and Hagedorn equations of state, is investigated. In each case, we solve the approximate gravitational field equations, obtained in the high-density limit, determine the equation which governs the formation of apparent horizons and investigate the conditions for the formation of naked singularities. Though, naively, one would expect the increased effective energy density on the brane to favor the formation of black holes over naked singularities, we find that, for the types of fluid considered, this is not the case. However, the black hole solutions differ substantially from their general-relativistic counterparts and brane world corrections often play a role analogous to charge in general relativity. As an astrophysical application of this work, the possibility that energy emission from a Hagedorn fluid collapsing to form a naked singularity may be a source of GRBs in the brane world is also considered.

  17. A Dynamical Systems Approach to Schwarzschild Null Geodesics

    CERN Document Server

    Belbruno, Edward

    2011-01-01

    The null geodesics of a Schwarzschild black hole are studied from a dynamical systems perspective. Written in terms of Kerr-Schild coordinates, the null geodesic equation takes on the simple form of a particle moving under the influence of a Newtonian central force with an inverse-cubic potential. We apply a McGehee transformation to these equations, which clearly elucidates the full phase space of solutions. All the null geodesics belong to one of four families of invariant manifolds and their limiting cases, further characterized by the angular momentum L of the orbit: for |L|>|L_c|, (1) the set that flow outward from the white hole, turn around, then fall into the black hole, (2) the set that fall inward from past null infinity, turn around outside the black hole to continue to future null infinity, and for |L|<|L_c|, (3) the set that flow outward from the white hole and continue to future null infinity, (4) the set that flow inward from past null infinity and into the black hole. The critical angular m...

  18. Frenet-Serret formalism for null world lines

    CERN Document Server

    Bini, Donato; Jantzen, Robert T

    2014-01-01

    The Frenet-Serret curve analysis is extended from nonnull to null trajectories in a generic spacetime using the Newman-Penrose formalism, recovering old results which are not well known and clarifying the associated Fermi-Walker transport which has been left largely unexplored in the literature. This machinery is then used to discuss null circular orbits in stationary axisymmetric spacetimes using the Kerr spacetime as a concrete example, and to integrate the equations of parallel transport along null geodesics in any spacetime.

  19. The Schwinger Model on the Null-Plane

    Science.gov (United States)

    Casana, R.; Pimentel, B. M.; Zambrano, G. E. R.

    We study the Schwinger Model on the null-plane using the Dirac method for constrained systems. The fermion field is analyzed using the natural null-plane projections coming from the γ-algebra and it is shown that the fermionic sector of the Schwinger Model has only second class constraints. However, the first class constraints are exclusively of the bosonic sector. Finally, we establish the graded Lie algebra between the dynamical variables, via generalized Dirac bracket in the null-plane gauge, which is consistent with every constraint of the theory.

  20. Null fields in the outer Jovian magnetosphere: Ulysses observations

    Science.gov (United States)

    Haynes, P. L.; Balogh, A.; Dougherty, M. K.; Southwood, D. J.; Fazakerley, A.; Smith, E. J.

    1994-01-01

    This paper reports on a magnetic field phenomenon, hereafter referred to as null fields, which were discovered during the inbound pass of the recent flyby of Jupiter by the Ulysses spacecraft. These null fields which were observed in the outer dayside magnetosphere are characterised by brief but sharp decreases of the field magnitude to values less than 1 nT. The nulls are distinguished from the current sheet signatures characteristic of the middle magnetosphere by the fact that the field does not reverse across the event. A field configuration is suggested that accounts for the observed features of the events.

  1. The Density of Coronal Null Points from Hinode and MDI

    CERN Document Server

    Longcope, Dana; DeForest, Craig

    2009-01-01

    Magnetic null points can be located numerically in a potential field extrapolation or their average density can be estimated from the Fourier spectrum of a magnetogram. We use both methods to compute the null point density from a quiet Sun magnetogram made with Hinode's NFI and from magnetograms from SOHO's MDI in both its high-resolution and low-resolution modes. All estimates of the super-chromospheric column density (z>1.5 Mm) agree with one another and with the previous measurements: 0.003 null points per square Mm of solar surface.

  2. The Importance of Phase in Nulling Interferometry and a Three Telescope Closure-Phase Nulling Interferometer Concept

    OpenAIRE

    Danchi, W. C.; Rajagopal, J.; Kuchner, M.; Richardson, J; Deming, D.

    2006-01-01

    We discuss the theory of the Bracewell nulling interferometer and explicitly demonstrate that the phase of the "white light" null fringe is the same as the phase of the bright output from an ordinary stellar interferometer. As a consequence a "closure phase" exists for a nulling interferometer with three or more telescopes. We calculate the phase offset as a function of baseline length for an Earth-like planet around the Sun at 10 pc, with a contrast ratio of $10^{-6}$ at 10 $\\mu$m. The magni...

  3. Waves and null congruences in a draining bathtub

    CERN Document Server

    Dempsey, David

    2016-01-01

    We study wave propagation in a draining bathtub: a fluid-mechanical black hole analogue in which perturbations are governed by a Klein-Gordon equation on an effective Lorentzian geometry. Like the Kerr spacetime, the draining bathtub geometry possesses an (effective) horizon, an ergosphere and null circular orbits. We propose that a `pulse' disturbance may be used to map out the light-cone of the effective geometry. First, we apply the eikonal approximation to elucidate the link between wavefronts, null geodesic congruences and the Raychaudhuri equation. Next, we solve the wave equation numerically in the time domain using the method of lines. Starting with Gaussian initial data, we demonstrate that a pulse will propagate along a null congruence and thus trace out the light-cone of the effective geometry. Our numerical results reveal features, such as wavefront intersections, frame-dragging, winding and interference effects, that are closely associated with the presence of null circular orbits and the ergosph...

  4. A new dynamic null model for phylogenetic community structure.

    Science.gov (United States)

    Pigot, Alex L; Etienne, Rampal S

    2015-02-01

    Phylogenies are increasingly applied to identify the mechanisms structuring ecological communities but progress has been hindered by a reliance on statistical null models that ignore the historical process of community assembly. Here, we address this, and develop a dynamic null model of assembly by allopatric speciation, colonisation and local extinction. Incorporating these processes fundamentally alters the structure of communities expected due to chance, with speciation leading to phylogenetic overdispersion compared to a classical statistical null model assuming equal probabilities of community membership. Applying this method to bird and primate communities in South America we show that patterns of phylogenetic overdispersion - often attributed to negative biotic interactions - are instead consistent with a species neutral model of allopatric speciation, colonisation and local extinction. Our findings provide a new null expectation for phylogenetic community patterns and highlight the importance of explicitly accounting for the dynamic history of assembly when testing the mechanisms governing community structure.

  5. Dynamics of a Spherical Null Shell within the Distributional Formalism

    OpenAIRE

    Khakshournia, Samad; Mansouri, Reza

    2004-01-01

    Dynamics of a null thin shell immersed in a generic spherically symmetric spacetime is obtained within the distributional formalism. It has been shown that the distributional formalism leads to the same result as in the conventional formalism.

  6. Estimating the Proportion of True Null Hypotheses for Multiple Comparisons

    National Research Council Canada - National Science Library

    Hongmei Jiang; RW Doerge

    2008-01-01

    ...) controlling procedures are too conservative. Although false discovery rate (FDR) procedures have been suggested as having greater power, the control itself is not exact and depends on the proportion of true null hypotheses...

  7. Glutathione-S-transferase M1 polymorphisms on the susceptibility to esophageal cancer among three Chinese minorities: Kazakh, Tajik and Uygur

    Institute of Scientific and Technical Information of China (English)

    Xiao-Mei Lu; Ting Yang; Shu-Yong Xu; Hao Wen; Xing Wang; Zhi-Hui Ren; Yan Zhang; Wei Wang

    2006-01-01

    AIM: To investigate the glutathione-S-transferase M1 (GSTM1) polymorphisms in three Chinese minorities,Kazakh, Uygur, and Tajik; and the pathological significance of GSTM1 polymorphisms in esophageal carcinogenesis in Kazakh.METHODS: A total of 1121 blood samples (442 males and 679 females) were obtained from healthy Kazakh (654), Uygur (412) and Tajik (55). Primary esophageal squamous cell cancer (ESCC) tissues from Kazakh were obtained from 116 patients who underwent surgery.GSTM1 polymorphisms were analyzed by a combined approach of PCR and electrophoresis techniques.RESULTS: GSTM1 null genotype was found in 62.63% Uygur, 50.91% Tajik and 47.40% Kazakh. A significantly higher frequency of GSTM1 null genotype in Uygur was observed compared with Kazakh (OR: 1.859, 95% CI: 1.445 -2.391, χ2 = 23.71, P = 0.000). In addition,GSTM1 null genotype was found in 23.53% of welldifferentiated ESCC in Kazakh, in 49.23% of poorly differentiated ESCC, with a significant difference (OR:3.152, 95% CI: 1.403-7.080, χ2 = 8.018, P = 0.007).CONCLUSION: There is a marked difference in the frequency of common GSTM1 null genotype between Uygur and Kazakh. GSTM1 null genotype is associated with differentiation of ESCC in Kazakh.

  8. Magnetoacoustic shock formation near a magnetic null point

    OpenAIRE

    Gruszecki, M. (Marcin); Vasheghani Farahani, Soheil; Nakariakov, V. M.; Arber, T. D.

    2011-01-01

    We investigate the interaction of nonlinear fast magnetoacoustic waves with a magnetic null point in connection with the triggering of solar flares. \\ud \\ud Methods. We model the propagation of fast, initially axisymmetric waves towards a two-dimensional isothermal magnetic null point in terms of ideal magnetohydrodynamic equations. The numerical simulations are carried out with the Lagrangian remap code Lare2D. \\ud \\ud Results. Dynamics of initially axisymmetric fast pulses of small amplitud...

  9. Development of New Sputter System by Magnetic Null Plasma

    OpenAIRE

    敦田, 悟; 楊, 鍾煥; 川尻, 晋平; 成, 烈[ブン; 本田, 親久; 大坪, 昌久

    2004-01-01

    Abstract ###A new type of plasma system based on the magnetic neutral loop discharge (NLD) concept ###has been developed for sputter application. This system is characterized by plasma production ###around the multi null magnetic field on the electrode surface, where a capacitive RF electric ###field is applied. From the experimental results and numerical analysis of electron behavior in ###this system, we found that electrons around the magnetic null region on the target surface ###moved in ...

  10. Magnetic null points in kinetic simulations of space plasmas

    OpenAIRE

    Olshevsky, Vyacheslav; Deca, Jan; Divin, Andrey; Peng, Ivy Bo; Markidis, Stefano; Innocenti, Maria Elena; Cazzola, Emanuele; Lapenta, Giovanni

    2015-01-01

    We present a systematic attempt to study magnetic null points and the associated magnetic energy conversion in kinetic Particle-in-Cell simulations of various plasma configurations. We address three-dimensional simulations performed with the semi-implicit kinetic electromagnetic code iPic3D in different setups: variations of a Harris current sheet, dipolar and quadrupolar magnetospheres interacting with the solar wind; and a relaxing turbulent configuration with multiple null points. Spiral n...

  11. Designing asynchronous circuits using NULL convention logic (NCL)

    CERN Document Server

    Smith, Scott

    2009-01-01

    Designing Asynchronous Circuits using NULL Convention Logic (NCL) begins with an introduction to asynchronous (clockless) logic in general, and then focuses on delay-insensitive asynchronous logic design using the NCL paradigm. The book details design of input-complete and observable dual-rail and quad-rail combinational circuits, and then discusses implementation of sequential circuits, which require datapath feedback. Next, throughput optimization techniques are presented, including pipelining, embedding registration, early completion, and NULL cycle reduction. Subsequently, low-power design

  12. Null controllability of a cascade system of Schrodinger equations

    Directory of Open Access Journals (Sweden)

    Marcos Lopez-Garcia

    2016-03-01

    Full Text Available This article presents a control problem for a cascade system of two linear N-dimensional Schrodinger equations. We address the problem of null controllability by means of a control supported in a region not satisfying the classical geometrical control condition. The proof is based on the application of a Carleman estimate with degenerate weights to each one of the equations and a careful analysis of the system in order to prove null controllability with only one control force.

  13. Using Multivalued Logic in Relational Database Containing Null Value

    Institute of Scientific and Technical Information of China (English)

    马宗民; YanLi

    1996-01-01

    In this paper,several kinds of multivalued logic for relational database and their developing process are presented on the basis of null value's semantics.A new 5 valued logic is led into relational database containing null value.The feasibility and necessity of using 5 valued logic are expounded.Comparative calculation and logical calculation under 5 valued logic are defined at the end of the paper.

  14. Shear-free Null Quasi-Spherical Spacetimes

    CERN Document Server

    Bartnik, R A

    1997-01-01

    The residual gauge freedom within the null quasi-spherical coordinate condition is studied, for spacetimes admitting an {\\em expanding, shear-free} null foliation. The freedom consists of a boost and rotation at each coordinate sphere, corresponding to a specification of inertial frame at each sphere. Explicit formulae involving arbitrary functions of two variables are obtained for the accelerated Minkowski, Schwarzschild, and Robinson-Trautman spacetimes. These examples will be useful as test metrics in numerical relativity.

  15. Overt and Null Subject Pronouns in Jordanian Arabic

    Directory of Open Access Journals (Sweden)

    Islam M. Al-Momani

    2015-08-01

    Full Text Available The paper aims at examining the role that morphology plays in allowing and/or motivating sentences in Jordanian Arabic (hereafter JA to be formed with or without subject pronouns. It also aims at giving a comprehensive and descriptive presentation of the distribution of overt and null subject pronouns in JA, and tries to determine to what extent there is optionality in its system. Keywords: null subject pronouns, overt subjects, pro-drop languages, verbal inflectional morphology

  16. The geometry of D=11 null killing spinors

    Energy Technology Data Exchange (ETDEWEB)

    Gauntlett, Jerome P.; Gutowski, Jan B. E-mail: gutowski@maths.ox.ac.uk; Stathis Pakis

    2003-12-01

    We determine the necessary and sufficient conditions on the metric and the four-form for the most general bosonic supersymmetric configurations of D=11 supergravity which admit a null Killing spinor i.e. a Killing spinor which can be used to construct a null Killing vector. This class covers all supersymmetric time-dependent configurations and completes the classification of the most general supersymmetric configurations initiated in hep-th/0212008. (author)

  17. The Geometry of D=11 Null Killing Spinors

    CERN Document Server

    Gauntlett, J P; Pakis, S

    2003-01-01

    We determine the necessary and sufficient conditions on the metric and the four-form for the most general bosonic supersymmetric configurations of D=11 supergravity which admit a null Killing spinor i.e. a Killing spinor which can be used to construct a null Killing vector. This class covers all supersymmetric time-dependent configurations and completes the classification of the most general supersymmetric configurations initiated in hep-th/0212008.

  18. Reconnection Experiments with Flux Ropes near 3D Magnetic Nulls

    Science.gov (United States)

    Vrublevskis, A.; Egedal, J.; Le, A.

    2012-12-01

    Magnetic reconnection has been predominantly investigated in two dimensions. However, depending on the topology and geometry of the magnetic field, a rich collection of magnetic reconnection scenarios is possible in 3D including reconnection at magnetic nulls. Nulls have been reported in the solar corona [1] and in Earth's magnetosphere [2], yet there are a limited number of laboratory observations. At the Versatile Toroidal Facility (VTF) we have implemented a new magnetic geometry with a pair of 3D null points in the background toroidal field. We form a flux rope along the background field and observe it to rapidly restructure and rewire as the nulls develop. We can adjust the topology of the configuration from one where a field line connects the nulls to one where the nulls are no longer linked. A suit of diagnostics will be deployed and results presented for the dynamics of the flux rope. [1] Fletcher et al., Astrophys. J. 554, 451(2001) [2] Xiao et al., Nat. Phys. 2, 478 (2006)

  19. Context-specific protection of TGFα null mice from osteoarthritis.

    Science.gov (United States)

    Usmani, Shirine E; Ulici, Veronica; Pest, Michael A; Hill, Tracy L; Welch, Ian D; Beier, Frank

    2016-07-26

    Transforming growth factor alpha (TGFα) is a growth factor involved in osteoarthritis (OA). TGFα induces an OA-like phenotype in articular chondrocytes, by inhibiting matrix synthesis and promoting catabolic factor expression. To better understand TGFα's potential as a therapeutic target, we employed two in vivo OA models: (1) post-traumatic and (2) aging related OA. Ten-week old and six-month old male Tgfa null mice and their heterozygous (control) littermates underwent destabilization of the medial meniscus (DMM) surgery. Disease progression was assessed histologically using the Osteoarthritis Research Society International (OARSI) scoring system. As well, spontaneous disease progression was analyzed in eighteen-month-old Tgfa null and heterozygous mice. Ten-week old Tgfa null mice were protected from OA progression at both seven and fourteen weeks post-surgery. No protection was seen however in six-month old null mice after DMM surgery, and no differences were observed between genotypes in the aging model. Thus, young Tgfa null mice are protected from OA progression in the DMM model, while older mice are not. In addition, Tgfa null mice are equally susceptible to spontaneous OA development during aging. Thus, TGFα might be a valuable therapeutic target in some post-traumatic forms of OA, however its role in idiopathic disease is less clear.

  20. Genetic polymorphisms of glutathione-s-transferase M1 and T1 genes with risk of diabetic retinopathy in Iranian population

    Directory of Open Access Journals (Sweden)

    Elham Moasser

    2014-05-01

    Full Text Available Objective(s:To the best of our knowledge, this is the first report on the contributions of GST genetic variants to the risk of diabetic retinopathy in an Iranian population. Therefore, the objective of this study was to determine whether sequence variation in glutathione S-transferase gene (GSTM1 and GSTT1 is associated with development of diabetic retinopathy in type 2 diabetes mellitus (T2DM Iranian patients. Materials and Methods: A total of 605 subjects were investigated in this case-control study; Study groups consisted of 201 patients with diabetic retinopathy (DR, 203 subjects with no clinically significant signs of DR and a group of 201 cases of healthy volunteers with no clinical evidence of diabetes mellitus or any other diseases. The GSTM1 and GSTT1 were genotyped by multiplex-polymerase chain reaction (multiplex-PCR analysis in all 404 T2DM patients and 201 healthy individuals served as control. Results: Increased odds ratio showed that GSTM1-null genotype had a moderately higher occurrence in T2DM patients (OR=1.43, 95% CI=1.01–2.04; P=0.03 than in healthy individuals. However, the frequency of GSTT1 genotype (OR=1.41; 95% CI=0.92-2.18; P=0.09 was not significantly different comparing both groups. Although, regression analysis in T2DM patients showed that GSTM1 and GSTT1 genotypes are not associated with T2DM retinopathy development. Conclusion: Our findings suggest that GSTM1 and GSTT1 genotypes might not be involved in the pathogenesis of type 2 diabetes mellitus retinopathy in the Southern Iranian population. However, further investigations are needed to confirm these results in other larger populations.

  1. Evaluation of hepatic glutathione transferase Mu 1 and Theta 1 activities in humans and mice using genotype information.

    Science.gov (United States)

    Arakawa, Shingo; Fujimoto, Kazunori; Kato, Ayako; Endo, Seiko; Fukahori, Aiko; Shinagawa, Akira; Fischer, Thomas; Mueller, Juergen; Takasaki, Wataru

    2012-03-01

    We investigated the impact of glutathione transferases Mu 1 (GSTM1)- and glutathione transferase Theta 1 (GSTT1)-null genotypes on hepatic GST activities in humans and compared the results with those of Gstm1- and Gstt1-null mice. In liver with GSTM1/Gstm1-null genotype, GST activity toward p-nitrobenzyl chloride (NBC) was significantly decreased in both humans and mice. In addition, in liver with GSTT1/Gstt1-null genotype, GST activity toward dichloromethane (DCM) was significantly decreased in both humans and mice. Therefore, null genotypes of GSTM1/Gstm1 and GSTT1/Gstt1 are considered to decrease hepatic GST activities toward NBC and DCM, respectively, in both humans and mice. This observation shows the functional similarity between humans and mice for GSTM1 and GSTT1 toward some substrates. In the case of NBC and DCM, Gst-null mice would be relevant models for humans with GST-null genotype. In addition, decreases in GST activities toward 1,2-dichloro-4-nitrobenzene, trans-4-phenyl-3-buten-2-one, and 1-chloro-2,4,-dinitrobenzene were observed in Gstm1-null mice, and a decrease in GST activity toward 1,2-epoxy-3-(p-nitrophenoxy)propane was observed in Gstt1-null mice. However, an impact of GST-null genotypes on GST activities toward these substrates was not observed in humans. In the case of these mouse-specific substrates, Gst-null mice may be relevant models for humans regardless of GST genotype, because GST activities, which are higher in wild-type mice than in humans, were eliminated in Gst-null mice. This study shows that comparison of hepatic GST activities between humans and mice using genotype information would be valuable in using Gst-null mice as human models.

  2. Three-dimensional magnetic reconnection through a moving magnetic null

    Directory of Open Access Journals (Sweden)

    V. S. Lukin

    2011-11-01

    Full Text Available A computational study of three-dimensional magnetic reconnection between two flux ropes through a moving reconnection site is presented. The configuration is considered in the context of two interacting spheromaks constrained by a perfectly conducting cylindrical boundary and oriented to form a single magnetic field null at its center. The initial magnetic field configuration is embedded into a uniform thermal plasma and is unstable to tilting. As the spheromaks tilt, their magnetic fields begin to reconnect at the null, subsequently displacing both the null and the reconnection site. The motion of the reconnection region and the magnetic null are shown to be correlated, with stronger correlation and faster reconnection observed in plasmas with lower thermal to magnetic pressure ratio. It is also shown that ion inertial effects allow for yet faster reconnection, but do not qualitatively change the dynamics of the process. Implications of the coupling between moving magnetic nulls and reconnection sites, as well as of possible mechanisms for fast reconnection through a moving reconnection region, are discussed. The simulations are conducted using both single-fluid and Hall MHD plasma models within the HiFi multi-fluid modeling framework.

  3. Three-dimensional magnetic reconnection through a moving magnetic null

    Science.gov (United States)

    Lukin, V. S.; Linton, M. G.

    2011-11-01

    A computational study of three-dimensional magnetic reconnection between two flux ropes through a moving reconnection site is presented. The configuration is considered in the context of two interacting spheromaks constrained by a perfectly conducting cylindrical boundary and oriented to form a single magnetic field null at its center. The initial magnetic field configuration is embedded into a uniform thermal plasma and is unstable to tilting. As the spheromaks tilt, their magnetic fields begin to reconnect at the null, subsequently displacing both the null and the reconnection site. The motion of the reconnection region and the magnetic null are shown to be correlated, with stronger correlation and faster reconnection observed in plasmas with lower thermal to magnetic pressure ratio. It is also shown that ion inertial effects allow for yet faster reconnection, but do not qualitatively change the dynamics of the process. Implications of the coupling between moving magnetic nulls and reconnection sites, as well as of possible mechanisms for fast reconnection through a moving reconnection region, are discussed. The simulations are conducted using both single-fluid and Hall MHD plasma models within the HiFi multi-fluid modeling framework.

  4. Long-term Observations of Three Nulling Pulsars

    CERN Document Server

    Young, N J; Stappers, B W; Lyne, A G; Kramer, M

    2015-01-01

    We present an analysis of approximately 200 hours of observations of the pulsars J1634$-$5107, J1717$-$4054 and J1853$+$0505, taken over the course of 14.7 yr. We show that all of these objects exhibit long term nulls and radio-emitting phases (i.e. minutes to many hours), as well as considerable nulling fractions (NFs) in the range $\\sim67\\,\\% - 90\\,\\%$. PSR J1717$-$4054 is also found to exhibit short timescale nulls ($1 - 40~P$) and burst phases ($\\lesssim 200~P$) during its radio-emitting phases. This behaviour acts to modulate the NF, and therefore the detection rate of the source, over timescales of minutes. Furthermore, PSR J1853$+$0505 is shown to exhibit a weak emission state, in addition to its strong and null states, after sufficient pulse integration. This further indicates that nulls may often only represent transitions to weaker emission states which are below the sensitivity thresholds of particular observing systems. In addition, we detected a peak-to-peak variation of $33\\pm1\\,\\%$ in the spin-...

  5. Visible Nulling Coronagraphy Testbed Development for Exoplanet Detection

    Science.gov (United States)

    Lyon, Richard G.; Clampin, Mark; Woodruff, Robert A.; Vasudevan, Gopal; Thompson, Patrick; Chen, Andrew; Petrone, Peter; Booth, Andrew; Madison, Timothy; Bolcar, Matthew; Noecker, M. Charley; Kendrick, Stephen; Melnick, Gary; Tolls, Volker

    2010-01-01

    Three of the recently completed NASA Astrophysics Strategic Mission Concept (ASMC) studies addressed the feasibility of using a Visible Nulling Coronagraph (VNC) as the prime instrument for exoplanet science. The VNC approach is one of the few approaches that works with filled, segmented and sparse or diluted aperture telescope systems and thus spans the space of potential ASMC exoplanet missions. NASA/Goddard Space Flight Center (GSFC) has a well-established effort to develop VNC technologies and has developed an incremental sequence of VNC testbeds to advance the this approach and the technologies associated with it. Herein we report on the continued development of the vacuum Visible Nulling Coronagraph testbed (VNT). The VNT is an ultra-stable vibration isolated testbed that operates under high bandwidth closed-loop control within a vacuum chamber. It will be used to achieve an incremental sequence of three visible light nulling milestones of sequentially higher contrasts of 10(exp 8) , 10(exp 9) and 10(exp 10) at an inner working angle of 2*lambda/D and ultimately culminate in spectrally broadband (>20%) high contrast imaging. Each of the milestones, one per year, is traceable to one or more of the ASMC studies. The VNT uses a modified Mach-Zehnder nulling interferometer, modified with a modified "W" configuration to accommodate a hex-packed MEMS based deformable mirror, a coherent fiber bundle and achromatic phase shifters. Discussed will be the optical configuration laboratory results, critical technologies and the null sensing and control approach.

  6. The causal topology of neutral 4-manifolds with null boundary

    CERN Document Server

    Georgiou, Nikos

    2016-01-01

    This paper considers aspects of 4-manifold topology from the point of view of a neutral metric, a point of view we call neutral causal topology. In particular, we construct and investigate neutral 4-manifolds with null boundary that arise from canonical 3- and 4-dimensional settings. A null hypersurface is foliated by its normal and, in the neutral case, inherits a pair of totally null planes at each point. This paper focuses on this structure in a number of classical settings The first construction is the conformal compactification of flat neutral 4-space into the 4-ball. The null foliation on the boundary in this case is the Hopf fibration on the 3-sphere and the totally null planes in the boundary are integrable. The metric on the 4-ball is a conformally flat, scalar-flat, positive Ricci curvature neutral metric. The second constructions are subsets of the 4-dimensional space of oriented geodesics in a 3-dimensional space-form, equipped with its canonical neutral metric. We consider all oriented geodesics ...

  7. The appearance, motion, and disappearance of three-dimensional magnetic null points

    CERN Document Server

    Murphy, Nicholas A; Haynes, Andrew L

    2015-01-01

    While theoretical models and simulations of magnetic reconnection often assume symmetry such that the magnetic null point when present is co-located with a flow stagnation point, the introduction of asymmetry typically leads to non-ideal flows across the null point. To understand this behavior, we present exact expressions for the motion of three-dimensional linear null points. The most general expression shows that linear null points move in the direction along which the vector field and its time derivative are antiparallel. Null point motion in resistive magnetohydrodynamics results from advection by the bulk plasma flow and resistive diffusion of the magnetic field, which allows non-ideal flows across topological boundaries. Null point motion is described intrinsically by parameters evaluated locally; however, global dynamics help set the local conditions at the null point. During a bifurcation of a degenerate null point into a null-null pair or the reverse, the instantaneous velocity of separation or conv...

  8. Association study of Glutathione S-Transferase polymorphisms and risk of endometriosis in an Iranian population

    Science.gov (United States)

    Hassani, Mina; Saliminejad, Kioomars; Heidarizadeh, Masood; Kamali, Koorosh; Memariani, Toktam; Khorram Khorshid, Hamid Reza

    2016-01-01

    Background: Endometriosis influenced by both genetic and environmental factors. Associations of glutathione S-transferases (GSTs) genes polymorphisms in endometriosis have been investigated by various researchers; however, the results are not consistent. Objective: We examined the associations of GSTM1 and GSTT1 null genotypes and GSTP1 313 A/G polymorphisms with endometriosis in an Iranian population. Materials and Methods: In this case-control study, 151 women with diagnosis of endometriosis and 156 normal healthy women as control group were included. The genotyping was determined using multiplex PCR and PCR- RFLP methods. Results: The GSTM1 null genotype was significantly higher (p=0.027) in the cases (7.3%) than the control group (1.3%). There was no significant difference between the frequency of GSTT1 genotypes between the cases and controls. The GSTP1 313 AG genotype was significantly lower (p=0.048) in the case (33.1%) than the control group (44.4%). Conclusion: Our results showed that GSTM1 and GSTP1 polymorphisms may be associated with susceptibility of endometriosis in Iranian women. PMID:27351025

  9. Thermodynamical interpretation of the geometrical variables associated with null surfaces

    CERN Document Server

    Chakraborty, Sumanta

    2015-01-01

    The emergent gravity paradigm interprets gravitational field equations as a describing the thermodynamic limit of the underlying statistical mechanics of microscopic degrees of freedom of the spacetime. The connection is established by attributing a heat density Ts to the null surfaces where T is the appropriate Davies-Unruh temperature and s is the entropy density. The field equations can be obtained from a thermodynamic variational principle which extremises the total heat density of all null surfaces. The explicit form of s determines the nature of the theory. We explore the consequences of this paradigm for an arbitrary null surface and highlight the thermodynamic significance of various geometrical quantities. In particular, we show that: (a) A conserved current, associated with the time development vector in a natural fashion, has direct thermodynamic interpretation in all Lanczos-Lovelock models of gravity. (b) One can generalize the notion of gravitational momentum, introduced in arXiv 1506.03814 to a...

  10. Characterizing the Properties of Coronal Magnetic Null Points

    Science.gov (United States)

    Barnes, Graham; DeRosa, Marc; Wagner, Eric

    2015-08-01

    The topology of the coronal magnetic field plays a role in a wide range of phenomena, from Coronal Mass Ejections (CMEs) through heating of the corona. One fundamental topological feature is the null point, where the magnetic field vanishes. These points are natural sites of magnetic reconnection, and hence the release of energy stored in the magnetic field. We present preliminary results of a study using data from the Helioseismic and Magnetic Imager aboard NASA's Solar Dynamics Observatory to characterize the properties and evolution of null points in a Potential Field Source Surface model of the coronal field. The main properties considered are the lifetime of the null points, their distribution with height, and how they form and subsequently vanish.This work is supported by NASA/LWS Grant NNX14AD45G, and by NSF/SHINE grant 1357018.

  11. Neutral evolution: A null model for language dynamics

    CERN Document Server

    Blythe, R A

    2011-01-01

    We review the task of aligning simple models for language dynamics with relevant empirical data, motivated by the fact that this is rarely attempted in practice despite an abundance of abstract models. We propose that one way to meet this challenge is through the careful construction of null models. We argue in particular that rejection of a null model must have important consequences for theories about language dynamics if modelling is truly to be worthwhile. Our main claim is that the stochastic process of neutral evolution (also known as genetic drift or random copying) is a viable null model for language dynamics. We survey empirical evidence in favour and against neutral evolution as a mechanism behind historical language changes, highlighting the theoretical implications in each case.

  12. Phase closure nulling: results from the 2009 campaign

    Science.gov (United States)

    Duvert, Gilles; Malbet, Fabien; Chelli, Alain; Millan-Gabet, Rafael; Monnier, John D.; Schaefer, Gail H.

    2010-07-01

    We present here a new observational technique, Phase Closure Nulling (PCN), which has the potential to obtain very high contrast detection and spectroscopy of faint companions to bright stars. PCN consists in measuring closure phases of fully resolved objects with a baseline triplet where one of the baselines crosses a null of the object visibility function. For scenes dominated by the presence of a stellar disk, the correlated flux of the star around nulls is essentially canceled out, and in these regions the signature of fainter, unresolved, scene object(s) dominates the imaginary part of the visibility in particular the closure phase. We present here the basics of the PCN method, the initial proof-of-concept observation, the envisioned science cases and report about the first observing campaign made on VLTI/AMBER and CHARA/MIRC using this technique.

  13. Phase Closure Nulling: results from the 2009 campaign

    CERN Document Server

    Duvert, Gilles; Chelli, Alain; Millan-Gabet, Rafael; Monnier, John D; Schaefer, Gail H

    2010-01-01

    We present here a new observational technique, Phase Closure Nulling (PCN), which has the potential to obtain very high contrast detection and spectroscopy of faint companions to bright stars. PCN consists in measuring closure phases of fully resolved objects with a baseline triplet where one of the baselines crosses a null of the object visibility function. For scenes dominated by the presence of a stellar disk, the correlated flux of the star around nulls is essentially canceled out, and in these regions the signature of fainter, unresolved, scene object(s) dominates the imaginary part of the visibility in particular the closure phase. We present here the basics of the PCN method, the initial proof-of-concept observation, the envisioned science cases and report about the first observing campaign made on VLTI/AMBER and CHARA/MIRC using this technique.

  14. Zn2+ Uptake in Streptococcus pyogenes: Characterization of adcA and lmb Null Mutants.

    Science.gov (United States)

    Tedde, Vittorio; Rosini, Roberto; Galeotti, Cesira L

    2016-01-01

    An effective regulation of metal ion homeostasis is essential for the growth of microorganisms in any environment and in pathogenic bacteria is strongly associated with their ability to invade and colonise their hosts. To gain a better insight into zinc acquisition in Group A Streptococcus (GAS) we characterized null deletion mutants of the adcA and lmb genes of Streptococcus pyogenes strain MGAS5005 encoding the orthologues of AdcA and AdcAII, the two surface lipoproteins with partly redundant roles in zinc homeostasis in Streptococcus pneumoniae. Null adcA and lmb mutants were analysed for their capability to grow in zinc-depleted conditions and were found to be more susceptible to zinc starvation, a phenotype that could be rescued by the addition of Zn2+ ions to the growth medium. Expression of AdcA, Lmb and HtpA, the polyhistidine triad protein encoded by the gene adjacent to lmb, during growth under conditions of limited zinc availability was examined by Western blot analysis in wild type and null mutant strains. In the wild type strain, AdcA was always present with little variation in expression levels between conditions of excess or limited zinc availability. In contrast, Lmb and HtpA were expressed at detectable levels only during growth in the presence of low zinc concentrations or in the null adcA mutant, when expression of lmb is required to compensate for the lack of adcA expression. In the latter case, Lmb and HtpA were overexpressed by several fold, thus indicating that also in GAS AdcA is a zinc-specific importer and, although it shares this function with Lmb, the two substrate-binding proteins do not show fully overlapping roles in zinc homeostasis.

  15. Nav 1.8-null mice show stimulus-dependent deficits in spinal neuronal activity

    Directory of Open Access Journals (Sweden)

    Wood John N

    2006-02-01

    Full Text Available Abstract Background The voltage gated sodium channel Nav 1.8 has a highly restricted expression pattern to predominantly nociceptive peripheral sensory neurones. Behaviourally Nav 1.8-null mice show an increased acute pain threshold to noxious mechanical pressure and also deficits in inflammatory and visceral, but not neuropathic pain. Here we have made in vivo electrophysiology recordings of dorsal horn neurones in intact anaesthetised Nav 1.8-null mice, in response to a wide range of stimuli to further the understanding of the functional roles of Nav 1.8 in pain transmission from the periphery to the spinal cord. Results Nav 1.8-null mice showed marked deficits in the coding by dorsal horn neurones to mechanical, but not thermal, -evoked responses over the non-noxious and noxious range compared to littermate controls. Additionally, responses evoked to other stimulus modalities were also significantly reduced in Nav 1.8-null mice where the reduction observed to pinch > brush. The occurrence of ongoing spontaneous neuronal activity was significantly less in mice lacking Nav 1.8 compared to control. No difference was observed between groups in the evoked activity to electrical activity of the peripheral receptive field. Conclusion This study demonstrates that deletion of the sodium channel Nav 1.8 results in stimulus-dependent deficits in the dorsal horn neuronal coding to mechanical, but not thermal stimuli applied to the neuronal peripheral receptive field. This implies that Nav 1.8 is either responsible for, or associated with proteins involved in mechanosensation.

  16. Optimization of myocardial nulling in pediatric cardiac MRI

    Energy Technology Data Exchange (ETDEWEB)

    Tham, Edythe B. [Stollery Children' s Hospital, University of Alberta, Department of Pediatrics, Division of Pediatric Cardiology, Edmonton, Alberta (Canada); Hung, Ryan W.; Crawley, Cinzia; Noga, Michelle L. [University of Alberta, Pediatric Radiology, Stollery Children' s Hospital, Edmonton (Canada); Myers, Kimberley A. [Alberta Children' s Hospital, Calgary (Canada)

    2012-04-15

    Current protocols to determine optimal nulling time in late enhancement imaging using adult techniques may not apply to children. To determine the optimal nulling time in anesthetised children, with the hypothesis that this occurs earlier than in adults. Sedated cardiac MRI was performed in 12 children (median age: 12 months, range: 1-60 months). After gadolinium administration, scout images at 2, 3, 4 and 10 min and phase sensitive inversion recovery (PSIR) images from 5 to 10 min were obtained. Signal-to-noise ratio (SNR) and inversion time (TI) were determined. Quality of nulling was assessed according to a grading score by three observers. Data was analysed using linear regression, Kruskal-Wallis and quadratic-weighted kappa statistics. One child with a cardiomyopathy had late enhancement. Good agreement in nulling occurred for scout images at 2 ({kappa} = 0.69) and 3 ({kappa} = 0.66) min and moderate agreement at 4 min ({kappa} = 0.57). Agreement of PSIR images was moderate at 7 min ({kappa} = 0.44) and poor-fair at other times. There were significant correlations between TI and scout time (r = 0.61, P < 0.0001), and SNR and kappa (r = 0.22, P = 0.017). Scout images at 2-4 min can be used to determine the TI with little variability. Image quality for PSIR images was highest at 7 min and SNR optimal at 7-9 min. TI increases with time and should be adjusted frequently during imaging. Thus, nulling times in children differ from nulling times in adults when using standard adult techniques. (orig.)

  17. Magnetoacoustic Waves in Stratified Atmospheres with a Magnetic Null Point

    Science.gov (United States)

    Tarr, Lucas A.; Linton, Mark; Leake, James E.

    2016-05-01

    Magnetic fields strongly modify the propagation of MHD waves from the photosphere to the low corona, as can be shown exactly for the most simple case of a uniform magnetic field and isothermally stratrified atmosphere. For slightly more realistic scenarios, where both the atmospheric parameters and the magnetic field vary spatially, the linear MHD equations typically cannot be solved analytically. We use the Lagrangian Remap code--a nonlinear, shock-capturing MHD code--to study the propagation of initially acoustic wavepackets through a model 2D atmosphere that includes a gravitationally stratified chromosphere, transition region, and low corona. The magnetic field is formed by three photospheric concentrations and includes a single magnetic null point, resulting in an inhomogeneous system with a magnetic dome topology. A portion of an introduced wavepacket will refract toward the null due to the varying Alfven speed. Waves incident on the equipartition contour surrounding the null, where the sound and Alfven speeds coincide, partially transmit, reflect, and mode convert between branches of the local dispersion relation. Outward propagating slow modes generated during conversion become strongly concentrated along the set of field lines passing near the null. Acoustic energy is beamed back downwards towards each photospheric foot point, and upwards along one separatrix that exits the top of the numerical domain. Changes in the dominant restoring force for the wavepacket, between the Lorentz and pressure gradient forces, lead to a buildup of current density along topologically important features of the system (the null point and its four separatrices) and can drive reconnection at the null point itself. Ohmic dissipation of the currents locally heats the plasma. We find that the amount of current accumulation depends on where the centroid of a wavepacket initial crosses the photosphere, but does not simply coincide with regions of open versus closed magnetic field or

  18. Null geodesics in a magnetically charged stringy black hole spacetime

    Science.gov (United States)

    Kuniyal, Ravi Shankar; Uniyal, Rashmi; Nandan, Hemwati; Purohit, K. D.

    2016-04-01

    We study the null geodesics of a four-dimensional magnetic charged black hole spacetime arising in string theory. The behaviour of effective potential in view of the different values of black hole parameters are analysed in the equatorial plane. The possible orbits for null geodesics are also discussed in view of the different values of the impact parameter. We have also calculated the frequency shift of photons in this spacetime. The results are compared to those obtained for the electrically charged stringy black hole spacetime and the Schwarzschild black hole spacetime in general relativity.

  19. Strength of the null singularity inside black holes

    CERN Document Server

    Burko, L M

    1999-01-01

    We study analytically the Cauchy horizon singularity inside spherically-symmetric charged black holes, coupled to a spherical self-gravitating, minimally-coupled, massless scalar field. We show that all causal geodesics terminate at the Cauchy horizon at a null singularity, which is weak according to the Tipler classification. The singularity is also deformationally-weak in the sense of Ori. Our results are valid at arbitrary points along the null singularity, in particular at late retarded times, when non-linear effects are crucial.

  20. $SQED_4$ and $QED_4$ on the null-plane

    CERN Document Server

    Casana, R; Zambrano, G E R

    2008-01-01

    We studied the scalar electrodynamics ($SQED_{4}$) and the spinor electrodynamics ($QED_{4}$) in the null-plane formalism. We followed the Dirac's technique for constrained systems to perform a detailed analysis of the constraint structure in both theories. We imposed the appropriated boundary conditions on the fields to fix the hidden subset first class constraints which generate improper gauge transformations and obtain an unique inverse of the second class constraint matrix. Finally, choosing the null-plane gauge condition, we determined the generalized Dirac brackets of the independent dynamical variables which via the correspondence principle give the (anti)-commutators for posterior quantization.

  1. On nulls of perturbed Fredholm operators and degenerate homoclinic bifurcations

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    It is known that small perturbations of a Fredholm operator L have nulls of dimension not larger than dirnN(L). In this paper for any given positive integer κ≤ dimN(L)we prove that there is a perturbation of L which has an exactlyκ-dimensional null. Actually,our proof gives a construction of the perturbation. We further apply our result to concrete examples of differential equations with degenerate homoclinic orbits, showing how many independent homoclinic orbits can be bifurcated from a perturbation.

  2. Magnetic Reconnection at a Three-dimensional Solar Null Point

    DEFF Research Database (Denmark)

    Frederiksen, Jacob Trier; Baumann, Gisela; Galsgaard, Klaus

    2012-01-01

    -like). The MHD simulations start out from a potential magnetic field containing a null-point, obtained from a SOHO magnetogram extrapolation approximately 8 hours before a C-class flare was observed. The magnetic field is stressed with a boundary motion pattern similar to the horizontal motions observed by SOHO......Using a specific solar null point reconnection case studied by Masson et al (2009; ApJ 700, 559) we investigate the dependence of the reconnection rate on boundary driving speed, numerical resolution, type of resistivity (constant or numerical), and assumed stratification (constant density or solar...

  3. Association of GST Genes Polymorphisms with Asthma in Tunisian Children

    Directory of Open Access Journals (Sweden)

    Chelbi Hanene

    2007-01-01

    Objective. We assessed whether polymorphisms of GST genes (GSTM1, GSTT1, and GSTP1 are associated with asthma and atopy among Tunisian children. Methods. 112 unrelated healthy individuals and 105 asthmatic (73 atopic and 32 nonatopic children were studied. Genotyping the polymorphisms in the GSTT1 and GSTM1 genes was performed using the multiplex PCR. The GSTP1 ILe105Val polymorphism was determined using PCR-RFLP. Results. GSTM1 null genotype was significantly associated with the increased risk of asthma (P=.002. Asthmatic children had a higher prevalence of the GSTP1Ile105 allele than the control group (43.8% and 33.5%, respectively; P=.002. Also, the presence of the GSTP1 homozygote Val/Val was less common in subjects with asthma than in control group. We have found that GSTT1 null genotype (GSTT10∗/0∗ was significantly associated with atopy (P=.008. Conclusion. Polymorphisms within genes of the GST superfamily were associated with risk of asthma and atopy in Tunisia.

  4. Novel FLG null mutations in Korean patients with atopic dermatitis and comparison of the mutational spectra in Asian populations.

    Science.gov (United States)

    Park, Joonhong; Jekarl, Dong Wook; Kim, Yonggoo; Kim, Jiyeon; Kim, Myungshin; Park, Young Min

    2015-09-01

    Filaggrin is essential for the development of the skin barrier. Mutations in the gene encoding filaggrin have been identified as major predisposing factors for atopic disorders. Molecular analysis of the FLG gene in this study showed nine null and one unclassified mutation in 13 of 81 Korean patients with atopic dermatitis (AD): five novel null mutations (i.e. p.S1405*, c.5671_5672delinsTA, p.W1947*, p.G2025* and p.E3070*); four reported null mutations (i.e. c.3321delA, p.S1515*, p.S3296* and p.K4022*); and one unclassified mutation (i.e. c.306delAAAGCACAG). These variants are nonsense, premature termination codon or in-frame deletion expected to cause loss-of-function of FLG. Genotype-phenotype correlation is not obvious in Korean AD patients with FLG null mutations. According to a review of the mutational spectra of the FLG gene in the Asian populations, FLG null mutations appeared to be unique in each population but some mutations such as p.R501*, c.3321delA, p.S1515*, p.S3296* and p.K4022* were commonly found in at least two of the selected Asian populations including Korean, Japanese, Chinese, Singaporean Chinese or Taiwanese. Further investigations on a larger group of Korean AD would be necessary to elucidate its clinical pathogenesis and mutational spectrum related to specific FLG null mutations for AD.

  5. GST M1-T1 null allele frequency patterns in geographically assorted human populations: a phylogenetic approach.

    Science.gov (United States)

    Kasthurinaidu, Senthilkumar Pitchalu; Ramasamy, Thirumurugan; Ayyavoo, Jayachitra; Dave, Dhvani Kirtikumar; Adroja, Divya Anantray

    2015-01-01

    Genetic diversity in drug metabolism and disposition is mainly considered as the outcome of the inter-individual genetic variation in polymorphism of drug-xenobiotic metabolizing enzyme (XME). Among the XMEs, glutathione-S-transferases (GST) gene loci are an important candidate for the investigation of diversity in allele frequency, as the deletion mutations in GST M1 and T1 genotypes are associated with various cancers and genetic disorders of all major Population Affiliations (PAs). Therefore, the present population based phylogenetic study was focused to uncover the frequency distribution pattern in GST M1 and T1 null genotypes among 45 Geographically Assorted Human Populations (GAHPs). The frequency distribution pattern for GST M1 and T1 null alleles have been detected in this study using the data derived from literatures representing 44 populations affiliated to Africa, Asia, Europe, South America and the genome of PA from Gujarat, a region in western India. Allele frequency counting for Gujarat PA and scattered plot analysis for geographical distribution among the PAs were performed in SPSS-21. The GST M1 and GST T1 null allele frequencies patterns of the PAs were computed in Seqboot, Gendist program of Phylip software package (3.69 versions) and Unweighted Pair Group method with Arithmetic Mean in Mega-6 software. Allele frequencies from South African Xhosa tribe, East African Zimbabwe, East African Ethiopia, North African Egypt, Caucasian, South Asian Afghanistan and South Indian Andhra Pradesh have been identified as the probable seven patterns among the 45 GAHPs investigated in this study for GST M1-T1 null genotypes. The patternized null allele frequencies demonstrated in this study for the first time addresses the missing link in GST M1-T1 null allele frequencies among GAHPs.

  6. GST M1-T1 null allele frequency patterns in geographically assorted human populations: a phylogenetic approach.

    Directory of Open Access Journals (Sweden)

    Senthilkumar Pitchalu Kasthurinaidu

    Full Text Available Genetic diversity in drug metabolism and disposition is mainly considered as the outcome of the inter-individual genetic variation in polymorphism of drug-xenobiotic metabolizing enzyme (XME. Among the XMEs, glutathione-S-transferases (GST gene loci are an important candidate for the investigation of diversity in allele frequency, as the deletion mutations in GST M1 and T1 genotypes are associated with various cancers and genetic disorders of all major Population Affiliations (PAs. Therefore, the present population based phylogenetic study was focused to uncover the frequency distribution pattern in GST M1 and T1 null genotypes among 45 Geographically Assorted Human Populations (GAHPs. The frequency distribution pattern for GST M1 and T1 null alleles have been detected in this study using the data derived from literatures representing 44 populations affiliated to Africa, Asia, Europe, South America and the genome of PA from Gujarat, a region in western India. Allele frequency counting for Gujarat PA and scattered plot analysis for geographical distribution among the PAs were performed in SPSS-21. The GST M1 and GST T1 null allele frequencies patterns of the PAs were computed in Seqboot, Gendist program of Phylip software package (3.69 versions and Unweighted Pair Group method with Arithmetic Mean in Mega-6 software. Allele frequencies from South African Xhosa tribe, East African Zimbabwe, East African Ethiopia, North African Egypt, Caucasian, South Asian Afghanistan and South Indian Andhra Pradesh have been identified as the probable seven patterns among the 45 GAHPs investigated in this study for GST M1-T1 null genotypes. The patternized null allele frequencies demonstrated in this study for the first time addresses the missing link in GST M1-T1 null allele frequencies among GAHPs.

  7. Gravitational Collapse of Null Radiation and a String fluid

    CERN Document Server

    Govinder, K S

    2003-01-01

    We consider the end state of collapsing null radiation with a string fluid. It is shown that, if the string is freely streaming, that a naked singularity can form (at least locally). The model has the advantage of not being asymptotically flat. We contrast this model with that of strange quark matter.

  8. MHD oscillations and waves near a magnetic null line

    Energy Technology Data Exchange (ETDEWEB)

    Bulanov, S.V.; Syrovatskii, S.I.

    1980-11-01

    An informative picture is drawn of the propagation of Alfven and magnetosonic waves in a two-dimensional magnetic field with a hyperbolic null point in the approximation of a cold plasma. The magnetosonic waves asymptotically transform into cylindrical waves. The wave amplitude increases toward the null point. A distortion of the plasma boundary produces excitation of noncylindrical magnetosonic waves. If the frequency of these waves is below the critical value, they will not penetrate into the plasma. Dissipation leads to a reflection of magnetosonic waves near the null line. Any arbitrarily slight dissipation leads to the appearance of a discrete spectrum of weakly damped Alfven oscillations. Oscillations of this type also occur in adiabatic confinement systems in which the magnetic field has null points. The nonlinear distortion of magnetosonic waves which leads to wave breaking and to the appearance of weak shock waves is studied. The amplitude of the magnetic field perturbations in a shock wave propagating toward the center asymptotically approaches a constant value.

  9. Magnetoacoustic shock formation near a magnetic null point

    Science.gov (United States)

    Gruszecki, M.; Vasheghani Farahani, S.; Nakariakov, , V. M.; Arber, T. D.

    2011-07-01

    Aims: We investigate the interaction of nonlinear fast magnetoacoustic waves with a magnetic null point in connection with the triggering of solar flares. Methods: We model the propagation of fast, initially axisymmetric waves towards a two-dimensional isothermal magnetic null point in terms of ideal magnetohydrodynamic equations. The numerical simulations are carried out with the Lagrangian remap code Lare2D. Results: Dynamics of initially axisymmetric fast pulses of small amplitude is found to be consistent with a linear analytical solution proposed earlier. The increase in the amplitude leads to the nonlinear acceleration of the compression pulse and deceleration of the rarefaction pulse and hence the distortion of the wave front. The pulse experiences nonlinear steepening in the radial direction either on the leading or the back slopes for the compression and rarefaction pulses, respectively. This effect is most pronounced in the directions perpendicular to the field. Hence, the nonlinear evolution of the fast pulse depends on the polar angle. The nonlinear steepening generates the sharp spikes of the electric current density. As in the uniform medium, the position of the shock formation also depends on the initial width of the pulse. Only sufficiently smooth and low-amplitude initial pulses can reach the vicinity of the null point, create there current density spikes, and initiate magnetic reconnection by seeding anomalous electrical resistivity. Steeper and higher amplitude initial pulses overturn at larger distance from the null point, and cannot trigger reconnection.

  10. Null point of discrimination in crustacean polarisation vision.

    Science.gov (United States)

    How, Martin J; Christy, John; Roberts, Nicholas W; Marshall, N Justin

    2014-07-15

    The polarisation of light is used by many species of cephalopods and crustaceans to discriminate objects or to communicate. Most visual systems with this ability, such as that of the fiddler crab, include receptors with photopigments that are oriented horizontally and vertically relative to the outside world. Photoreceptors in such an orthogonal array are maximally sensitive to polarised light with the same fixed e-vector orientation. Using opponent neural connections, this two-channel system may produce a single value of polarisation contrast and, consequently, it may suffer from null points of discrimination. Stomatopod crustaceans use a different system for polarisation vision, comprising at least four types of polarisation-sensitive photoreceptor arranged at 0, 45, 90 and 135 deg relative to each other, in conjunction with extensive rotational eye movements. This anatomical arrangement should not suffer from equivalent null points of discrimination. To test whether these two systems were vulnerable to null points, we presented the fiddler crab Uca heteropleura and the stomatopod Haptosquilla trispinosa with polarised looming stimuli on a modified LCD monitor. The fiddler crab was less sensitive to differences in the degree of polarised light when the e-vector was at -45 deg than when the e-vector was horizontal. In comparison, stomatopods showed no difference in sensitivity between the two stimulus types. The results suggest that fiddler crabs suffer from a null point of sensitivity, while stomatopods do not. © 2014. Published by The Company of Biologists Ltd.

  11. Design of a polarization nulling interferometer for exoplanet detection

    NARCIS (Netherlands)

    Spronck, J.; Vosteen, L.L.A.; Pereira, S.F.; Braat, J.J.M.

    2007-01-01

    We present the design of a new testbed experiment to demonstrate nulling interferometry using polarization properties. This three-beam set-up is perfectly symmetric with respect to the number of reflections and transmissions and should therefore allow a high rejection ratio in a wide spectral band.

  12. Nulling interferometry for exoplanet detection using polarization properties

    NARCIS (Netherlands)

    Spronck, J.; Pereira, S.F.; Braat, J.J.M.

    2006-01-01

    We present a new type of nulling interferometer that makes use of polarization properties to have on-axis destructive interference. The proposed design, which only involves commercial components and no achromatic device, is also suitable for internal modulation. This type of interferometer should en

  13. Compensation and optimization of dispersion in nulling interferometry

    NARCIS (Netherlands)

    Spronck, J.F.P.; Los, J.W.N.; Pereira, S.F.

    2008-01-01

    The optical properties of materials are wavelength-dependent. This property, called dispersion, affects the performance of a wide-band nulling interferometer by inducing wavelength-dependent phase differences between the arms of the interferometer. In this paper, we analyze the influence of dispersi

  14. Averaged null energy condition and quantum inequalities in curved spacetime

    CERN Document Server

    Kontou, Eleni-Alexandra

    2015-01-01

    The Averaged Null Energy Condition (ANEC) states that the integral along a complete null geodesic of the projection of the stress-energy tensor onto the tangent vector to the geodesic cannot be negative. ANEC can be used to rule out spacetimes with exotic phenomena, such as closed timelike curves, superluminal travel and wormholes. We prove that ANEC is obeyed by a minimally-coupled, free quantum scalar field on any achronal null geodesic (not two points can be connected with a timelike curve) surrounded by a tubular neighborhood whose curvature is produced by a classical source. To prove ANEC we use a null-projected quantum inequality, which provides constraints on how negative the weighted average of the renormalized stress-energy tensor of a quantum field can be. Starting with a general result of Fewster and Smith, we first derive a timelike projected quantum inequality for a minimally-coupled scalar field on flat spacetime with a background potential. Using that result we proceed to find the bound of a qu...

  15. Waves and null congruences in a draining bathtub

    Science.gov (United States)

    Dempsey, David; Dolan, Sam R.

    2016-04-01

    We study wave propagation in a draining bathtub: a black hole analogue in fluid mechanics whose perturbations are governed by a Klein-Gordon equation on an effective Lorentzian geometry. Like the Kerr spacetime, the draining bathtub geometry possesses an (effective) horizon, an ergosphere and null circular orbits. We propose here that a ‘pulse’ disturbance may be used to map out the light-cone of the effective geometry. First, we apply the eikonal approximation to elucidate the link between wavefronts, null geodesic congruences and the Raychaudhuri equation. Next, we solve the wave equation numerically in the time domain using the method of lines. Starting with Gaussian initial data, we demonstrate that a pulse will propagate along a null congruence and thus trace out the light-cone of the effective geometry. Our new results reveal features, such as wavefront intersections, frame-dragging, winding and interference effects, that are closely associated with the presence of null circular orbits and the ergosphere.

  16. Uniform Consistency for Nonparametric Estimators in Null Recurrent Time Series

    DEFF Research Database (Denmark)

    Gao, Jiti; Kanaya, Shin; Li, Degui

    2015-01-01

    This paper establishes uniform consistency results for nonparametric kernel density and regression estimators when time series regressors concerned are nonstationary null recurrent Markov chains. Under suitable regularity conditions, we derive uniform convergence rates of the estimators. Our...... results can be viewed as a nonstationary extension of some well-known uniform consistency results for stationary time series....

  17. Testing the null hypothesis: the forgotten legacy of Karl Popper?

    Science.gov (United States)

    Wilkinson, Mick

    2013-01-01

    Testing of the null hypothesis is a fundamental aspect of the scientific method and has its basis in the falsification theory of Karl Popper. Null hypothesis testing makes use of deductive reasoning to ensure that the truth of conclusions is irrefutable. In contrast, attempting to demonstrate the new facts on the basis of testing the experimental or research hypothesis makes use of inductive reasoning and is prone to the problem of the Uniformity of Nature assumption described by David Hume in the eighteenth century. Despite this issue and the well documented solution provided by Popper's falsification theory, the majority of publications are still written such that they suggest the research hypothesis is being tested. This is contrary to accepted scientific convention and possibly highlights a poor understanding of the application of conventional significance-based data analysis approaches. Our work should remain driven by conjecture and attempted falsification such that it is always the null hypothesis that is tested. The write up of our studies should make it clear that we are indeed testing the null hypothesis and conforming to the established and accepted philosophical conventions of the scientific method.

  18. Progress in broadband infrared nulling technology for TPF

    Science.gov (United States)

    Wallace, J. Kent; Brown, Ken; Bartos, Randall; Gappinger, Robert; Loya, Frank; Macdonald, Dan; Moser, Steve; Negron, John

    2005-01-01

    TPF-I has set for itself a host of challenging technical milestones along its path to demonstrating the feasibility of infrared nulling for planet detection Progress in each of these areas of technical development will be reviewed as well as progress in meeting the overarching technical milestones.

  19. Maxwell Fields and Shear-Free Null Geodesic Congruences

    CERN Document Server

    Newman, E

    2004-01-01

    We study and report on the class of vacuum Maxwell fields in Minkowski space that possess a non-degenerate, diverging, principle null vector field (null eigenvector field of the Maxwell tensor) that is tangent to a shear-free null geodesics congruence. These congruences can be either surface forming (the tangent vectors proportional to gradients) or not, i.e., the twisting congruences. In the non-twisting case, the associated Maxwell fields are precisely the Lienard-Wiechert fields, i.e., those Maxwell fields arising from an electric monopole moving on an arbitrary worldline. The null geodesic congruence is given by the generators of the light-cones with apex on the world-line. The twisting case is much richer, more interesting and far more complicated. In a twisting subcase, where our main interests lie, it can be given the following strange interpretation. If we allow the real Minkowski space to be complexified so that the real Minkowski coordinates x^a take complex values, i.e., x^a => z^a=x^a+iy^a with co...

  20. On the null distribution of Bayes factors in linear regression

    Science.gov (United States)

    We show that under the null, the 2 log (Bayes factor) is asymptotically distributed as a weighted sum of chi-squared random variables with a shifted mean. This claim holds for Bayesian multi-linear regression with a family of conjugate priors, namely, the normal-inverse-gamma prior, the g-prior, and...

  1. Entropy of Null Surfaces and Dynamics of Spacetime

    CERN Document Server

    Padmanabhan, T; Paranjape, Aseem

    2006-01-01

    The null surfaces of a spacetime act as one-way membranes and can block information for a corresponding family of observers (time-like curves). Since lack of information can be related to entropy, this suggests the possibility of assigning an entropy to the null surfaces of a spacetime. We motivate and introduce such an entropy functional in terms of the normal to the null surface and a fourth-rank divergence free tensor $P_{ab}^{cd}$ with the algebraic symmetries of the curvature tensor. Extremising this entropy then leads to field equations for the background metric of the spacetime. When $P_{ab}^{cd}$ is constructed from the metric alone, these equations are identical to Einstein's equations with an undetermined cosmological constant (which arises as an integration constant). More generally, if $P_{ab}^{cd}$ is allowed to depend on both metric and curvature in a polynomial form, one recovers the Lanczos-Lovelock gravity. In all these cases: (a) We only need to extremise the entropy associated with the null...

  2. Reassessing the Null-Subject Parameter in Second Language Acquisition.

    Science.gov (United States)

    Lantolf, James P.

    A study is presented that examines the null-subject parameter (NSP) and that seeks to attain the following objectives: (1) to assess the validity of the implicational hierarchy for the NSP, especially as proposed by Liceras (1989); and (2) to determine if there is any evidence to support the theory of the Weaker Logical Problem of Acquisition…

  3. Effectiveness of Null Signal Sky Localization in Pulsar Timing Arrays

    Science.gov (United States)

    Shafiq Hazboun, Jeffrey

    2017-01-01

    A null stream is constructed from the timing residuals of three pulsars by noting that the same source polarization amplitudes appear in the data stream from each pulsar. Linear combinations of a set of individual pulsar data streams can be shown to be a two-parameter family (the two sky position angles of the source) that can be minimized to determine the location of the source on the sky. Taking the product of a number of null streams allows for an even stronger localization of the gravitational wave's source; a large advantage in a PTA where there are more independent signals than other gravitational wave detectors. While a null stream contains the same information as any other data stream with the same number of pulsars, the statistics of a product of noisy signals is inherently different than for a sum of those same signals.A comparison of how null signal searches compare to other techniques for sky localization of PTA sources will be discussed, as well as an assessment of the types of searches for which the method may be useful.

  4. Null Lens Assembly for X-Ray Mirror Segments

    Science.gov (United States)

    Robinson, David W.

    2011-01-01

    A document discusses a null lens assembly that allows laser interferometry of 60 deg. slumped glass mirror segments used in x-ray mirrors. The assembly consists of four lenses in precise alignment to each other, with incorporated piezoelectric nanometer stepping actuators to position the lenses in six degrees of freedom for positioning relative to each other.

  5. Null Objects in Second Language Acquisition: Grammatical vs. Performance Models

    Science.gov (United States)

    Zyzik, Eve C.

    2008-01-01

    Null direct objects provide a favourable testing ground for grammatical and performance models of argument omission. This article examines both types of models in order to determine which gives a more plausible account of the second language data. The data were collected from second language (L2) learners of Spanish by means of four oral…

  6. Overt and Null Subject Pronouns in Jordanian Arabic

    Science.gov (United States)

    Al-Momani, Islam M.

    2015-01-01

    The paper aims at examining the role that morphology plays in allowing and/or motivating sentences in Jordanian Arabic (hereafter JA) to be formed with or without subject pronouns. It also aims at giving a comprehensive and descriptive presentation of the distribution of overt and null subject pronouns in JA, and tries to determine to what extent…

  7. Null controllability for a fourth order parabolic equation

    Institute of Scientific and Technical Information of China (English)

    YU Hang

    2009-01-01

    In the paper,the null interior controllability for a fourth order parabolic equation is obtained.The method Is based on Lebeau-Rabbiano inequality which is a quantitative unique continuation property for the sum of eigenfunctions of the Laplacian.

  8. Do Null Subjects (Mis-)Trigger Pro-Drop Grammars?

    Science.gov (United States)

    Frazier, Lyn

    2015-01-01

    Native speakers of English regularly hear sentences without overt subjects. Nevertheless, they maintain a [[superscript -]pro] grammar that requires sentences to have an overt subject. It is proposed that listeners of English recognize that speakers reduce predictable material and thus attribute null subjects to this process, rather than changing…

  9. Dispersion in nulling interferometry for exoplanet detection: experimental validation

    NARCIS (Netherlands)

    Spronck, J.F.P.; Los, J.W.N.; Pereira, S.F.

    2009-01-01

    It is well known that dispersion affects the performance of a wide-band nulling interferometer, since it induces wavelength-dependent phase differences between the arms of the interferometer. This property is used to create achromatic phase shift by combining several dielectric plates. In this paper

  10. An Approach for Search Based Testing of Null Pointer Exceptions

    NARCIS (Netherlands)

    Romano, D.; Di Penta, M.; Antoniol, G.

    2011-01-01

    Uncaught exceptions, and in particular null pointer exceptions (NPEs), constitute a major cause of crashes for software systems. Although tools for the static identification of potential NPEs exist, there is need for proper approaches able to identify system execution scenarios causing NPEs. This

  11. The appearance, motion, and disappearance of three-dimensional magnetic null points

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, Nicholas A., E-mail: namurphy@cfa.harvard.edu [Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138 (United States); Parnell, Clare E.; Haynes, Andrew L. [School of Mathematics and Statistics, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS (United Kingdom)

    2015-10-15

    While theoretical models and simulations of magnetic reconnection often assume symmetry such that the magnetic null point when present is co-located with a flow stagnation point, the introduction of asymmetry typically leads to non-ideal flows across the null point. To understand this behavior, we present exact expressions for the motion of three-dimensional linear null points. The most general expression shows that linear null points move in the direction along which the magnetic field and its time derivative are antiparallel. Null point motion in resistive magnetohydrodynamics results from advection by the bulk plasma flow and resistive diffusion of the magnetic field, which allows non-ideal flows across topological boundaries. Null point motion is described intrinsically by parameters evaluated locally; however, global dynamics help set the local conditions at the null point. During a bifurcation of a degenerate null point into a null-null pair or the reverse, the instantaneous velocity of separation or convergence of the null-null pair will typically be infinite along the null space of the Jacobian matrix of the magnetic field, but with finite components in the directions orthogonal to the null space. Not all bifurcating null-null pairs are connected by a separator. Furthermore, except under special circumstances, there will not exist a straight line separator connecting a bifurcating null-null pair. The motion of separators cannot be described using solely local parameters because the identification of a particular field line as a separator may change as a result of non-ideal behavior elsewhere along the field line.

  12. The appearance, motion, and disappearance of three-dimensional magnetic null points

    Science.gov (United States)

    Murphy, Nicholas A.; Parnell, Clare E.; Haynes, Andrew L.

    2015-10-01

    While theoretical models and simulations of magnetic reconnection often assume symmetry such that the magnetic null point when present is co-located with a flow stagnation point, the introduction of asymmetry typically leads to non-ideal flows across the null point. To understand this behavior, we present exact expressions for the motion of three-dimensional linear null points. The most general expression shows that linear null points move in the direction along which the magnetic field and its time derivative are antiparallel. Null point motion in resistive magnetohydrodynamics results from advection by the bulk plasma flow and resistive diffusion of the magnetic field, which allows non-ideal flows across topological boundaries. Null point motion is described intrinsically by parameters evaluated locally; however, global dynamics help set the local conditions at the null point. During a bifurcation of a degenerate null point into a null-null pair or the reverse, the instantaneous velocity of separation or convergence of the null-null pair will typically be infinite along the null space of the Jacobian matrix of the magnetic field, but with finite components in the directions orthogonal to the null space. Not all bifurcating null-null pairs are connected by a separator. Furthermore, except under special circumstances, there will not exist a straight line separator connecting a bifurcating null-null pair. The motion of separators cannot be described using solely local parameters because the identification of a particular field line as a separator may change as a result of non-ideal behavior elsewhere along the field line.

  13. Association between HLA-DRB1, HLA-DRQB1 alleles, and CD4(+)CD28(null) T cells in a Chinese population with coronary heart disease.

    Science.gov (United States)

    Sun, Wenjie; Cui, Ying; Zhen, Lihui; Huang, Lijuan

    2011-03-01

    CD4(+)CD28(null) T cells are present in increased numbers in the peripheral blood of patients with acute coronary syndrome. However, the triggers of expansion of these cells are unclear. Susceptibility to coronary heart disease (CHD) is strongly associated with alleles of human leukocyte antigen (HLA), but it is not equally strong in different human populations. The objective of the study was to investigate association between CD4(+)CD28(null) T cells and HLA-DRB1 alleles. The HLA alleles were determined by polymerase chain reaction with sequence-specific primers (PCR-SSP) method, in a group of CHD patients and control subjects from the same area. The number of CD4(+)CD28(null) T cells was measured using the flow cytometry technique. The HLA-DRB1*01 (RR = 4.705, P Chinese population, and increased numbers of CD4(+)CD28(null) T cells were found in association with HLA-DRB1*04 (17.1%) and DRB*01 (12.9%), while decreased numbers of CD4(+)CD28(null) T cells were present in subjects with DRB1*15 (0.8%). CHD in Chinese population is strongly associated with HLA-DRB1*01 and DRB1*04 haplotypes, and formation of CD4(+)CD28(null) T cells was related to HLA-DRB1*01, DRB1*04, and DRB1*15 alleles.

  14. Novel microsatellite markers for the oriental fruit moth Grapholita molesta (Lepidoptera: Tortricidae) and effects of null alleles on population genetics analyses.

    Science.gov (United States)

    Song, W; Cao, L-J; Wang, Y-Z; Li, B-Y; Wei, S-J

    2016-11-07

    The oriental fruit moth (OFM) Grapholita molesta (Lepidoptera: Tortricidae) is an important economic pest of stone and pome fruits worldwide. We sequenced the OFM genome using next-generation sequencing and characterized the microsatellite distribution. In total, 56,674 microsatellites were identified, with 11,584 loci suitable for primer design. Twenty-seven polymorphic microsatellites, including 24 loci with trinucleotide repeat and three with pentanucleotide repeat, were validated in 95 individuals from four natural populations. The allele numbers ranged from 4 to 40, with an average value of 13.7 per locus. A high frequency of null alleles was observed in most loci developed for the OFM. Three marker panels, all of the loci, nine loci with the lowest null allele frequencies, and nine loci with the highest null allele frequencies, were established for population genetics analyses. The null allele influenced estimations of genetic diversity parameters but not the OFM's genetic structure. Both a STRUCTURE analysis and a discriminant analysis of principal components, using the three marker panels, divided the four natural populations into three groups. However, more individuals were incorrectly assigned by the STRUCTURE analysis when the marker panel with the highest null allele frequency was used compared with the other two panels. Our study provides empirical research on the effects of null alleles on population genetics analyses. The microsatellites developed will be valuable markers for genetic studies of the OFM.

  15. GSTT1 null genotype contributes to lung cancer risk in asian populations: a meta-analysis of 23 studies.

    Directory of Open Access Journals (Sweden)

    Xin Yang

    Full Text Available BACKGROUND: Genetic variation in glutathione S-transferases (GSTs may contribute to lung cancer risk. Many studies have investigated the correlation between the Glutathione S-transferase T1 (GSTT1 null genotype and lung cancer risk in Asian population but yielded inconclusive results. METHODOLOGY/PRINCIPAL FINDINGS: We performed a meta-analysis of 23 studies including 4065 cases and 5390 controls. We assessed the strength of the association of GSTT1 with lung cancer risk and performed sub-group analyses by source of controls, smoking status, histological types, and sample size. A statistically significant correlation between GSTT1 null genotype and lung cancer in Asian population was observed (OR = 1.28, 95% CI = 1.10, 1.49; Pheterogeneity<0.001 and I(2 = 62.0%. Sub-group analysis revealed there was a statistically increased lung cancer risk in ever-smokers who carried the GSTT1 null genotype (OR = 1.94, 95% CI = 1.27, 2.96; P heterogeneity = 0.02 and I(2 = 58.1%. It was also indicated that GSTT1 null genotype could increase lung cancer risk among population-based studies (OR = 1.25, 95% CI = 1.04, 1.50; Pheterogeneity = 0.003 and I(2 = 56.8%. The positive association was also found in studies of sample size (≤500 participants (OR = 1.34, 95% CI = 1.10, 1.62; Pheterogeneity<0.001 and I(2 = 65.4%. CONCLUSIONS: These meta-analysis results suggest that GSTT1 null genotype is associated with a significantly increased risk of lung cancer in Asian population.

  16. Defective intestinal amino acid absorption in Ace2 null mice.

    Science.gov (United States)

    Singer, Dustin; Camargo, Simone M R; Ramadan, Tamara; Schäfer, Matthias; Mariotta, Luca; Herzog, Brigitte; Huggel, Katja; Wolfer, David; Werner, Sabine; Penninger, Josef M; Verrey, François

    2012-09-15

    Mutations in the main intestinal and kidney luminal neutral amino acid transporter B(0)AT1 (Slc6a19) lead to Hartnup disorder, a condition that is characterized by neutral aminoaciduria and in some cases pellagra-like symptoms. These latter symptoms caused by low-niacin are thought to result from defective intestinal absorption of its precursor L-tryptophan. Since Ace2 is necessary for intestinal B(0)AT1 expression, we tested the impact of intestinal B(0)AT1 absence in ace2 null mice. Their weight gain following weaning was decreased, and Na(+)-dependent uptake of B(0)AT1 substrates measured in everted intestinal rings was defective. Additionally, high-affinity Na(+)-dependent transport of L-proline, presumably via SIT1 (Slc6a20), was absent, whereas glucose uptake via SGLT1 (Slc5a1) was not affected. Measurements of small intestine luminal amino acid content following gavage showed that more L-tryptophan than other B(0)AT1 substrates reach the ileum in wild-type mice, which is in line with its known lower apparent affinity. In ace2 null mice, the absorption defect was confirmed by a severalfold increase of L-tryptophan and of other neutral amino acids reaching the ileum lumen. Furthermore, plasma and muscle levels of glycine and L-tryptophan were significantly decreased in ace2 null mice, with other neutral amino acids displaying a similar trend. A low-protein/low-niacin diet challenge led to differential changes in plasma amino acid levels in both wild-type and ace2 null mice, but only in ace2 null mice to a stop in weight gain. Despite the combination of low-niacin with a low-protein diet, plasma niacin concentrations remained normal in ace2 null mice and no pellagra symptoms, such as photosensitive skin rash or ataxia, were observed. In summary, mice lacking Ace2-dependent intestinal amino acid transport display no total niacin deficiency nor clear pellagra symptoms, even under a low-protein and low-niacin diet, despite gross amino acid homeostasis alterations.

  17. Proof of a Null Penrose Conjecture using a new Quasi-local Mass

    CERN Document Server

    Roesch, Henri

    2016-01-01

    We define an explicit quasi-local mass functional which is non-decreasing along all foliations (satisfying a convexity assumption) of null cones. We use this new functional to prove the null Penrose conjecture under fairly generic conditions.

  18. Magnetic Reconnection at a Three-dimensional Solar Null Point

    Science.gov (United States)

    Frederiksen, J. T.; Baumann, G.; Galsgaard, K.; Haugbølle, T.; Nordlund, Å.

    2012-04-01

    Using a specific solar null point reconnection case studied by Masson et al (2009; ApJ 700, 559) we investigate the dependence of the reconnection rate on boundary driving speed, numerical resolution, type of resistivity (constant or numerical), and assumed stratification (constant density or solar-like). The MHD simulations start out from a potential magnetic field containing a null-point, obtained from a SOHO magnetogram extrapolation approximately 8 hours before a C-class flare was observed. The magnetic field is stressed with a boundary motion pattern similar to the horizontal motions observed by SOHO during the period preceding the flare. The general behavior is nearly independent of driving speed and numerical resolution, and is also very similar in stratified and unstratified models, provided only that the boundary motions are slow enough.

  19. MHD Mode Conversion around a 2D Magnetic Null Point

    CERN Document Server

    McDougall, A M D; 10.1063/1.3099224

    2009-01-01

    Mode conversion occurs when a wave passes through a region where the sound and Alfven speeds are equal. At this point there is a resonance, which allows some of the incident wave to be converted into a different mode. We study this phenomenon in the vicinity of a two-dimensional, coronal null point. As a wave approaches the null it passes from low- to high-beta plasma, allowing conversion to take place. We simulate this numerically by sending in a slow magnetoacoustic wave from the upper boundary; as this passes through the conversion layer a fast wave can clearly be seen propagating ahead. Numerical simulations combined with an analytical WKB investigation allow us to determine and track both the incident and converted waves throughout the domain.

  20. Averaged-null-energy condition for electromagnetism in Minkowski spacetime

    Energy Technology Data Exchange (ETDEWEB)

    Folacci, A. (Universite de Corse, Faculte des Sciences, Boite Postale 52, 20250 Corti (France))

    1992-09-15

    We show, on four-dimensional Minkowski spacetime, that {l angle}{psi}{vert bar}{ital T}{sub {mu}{nu}}{vert bar}{psi}{r angle}, the renormalized expectation value in a general quantum state {vert bar}{psi}{r angle} of the stress-energy tensor for electromagnetism, satisfies the averaged-null-energy condition, i.e., that {integral}{ital d}{lambda}{l angle}{psi}{vert bar}{ital T}{sub {mu}{nu}}{vert bar}{psi}{r angle}{ital t}{sup {mu}}{ital t{nu}}{ge}0 where this integral is along complete null geodesics with an affine parameter {lambda} and tangent vector {ital t}{sup {mu}}.

  1. Avoid a Void: The Eradication of Null Dereferencing

    Science.gov (United States)

    Meyer, Bertrand; Kogtenkov, Alexander; Stapf, Emmanuel

    All object-oriented programs, but also those in C or Pascal as soon as they use pointers, are subject to the risk of run-time crash due to "null pointer dereferencing". Until recently this was the case even in statically typed languages. Tony Hoare has called this problem his "billion-dollar mistake". In the type system of ISO-standard Eiffel, the risk no longer exists: void safety (the absence of null pointer dereferencing) has become a property guaranteed by the type system and enforced by the compiler. The mechanism is fully implemented and major libraries and applications have been made void-safe. This presentation describes the principles of Eiffel's void safety, their implementation and the lessons gained.

  2. Null Fluids - A New Viewpoint of Galilean Fluids

    CERN Document Server

    Banerjee, Nabamita; Jain, Akash

    2015-01-01

    This article is a detailed version of our short letter `On equilibrium partition function for non-relativistic fluid' [arXiv:1505.05677] extended to include an anomalous $U(1)$ symmetry. We construct a relativistic system, which we call null fluid and show that it is in one-to-one correspondence with a Galilean fluid living in one lower dimension. The correspondence is based on light cone reduction, which is known to reduce the Poincare symmetry of a theory to Galilean in one lower dimension. We show that the proposed null fluid and the corresponding Galilean fluid have exactly same symmetries, thermodynamics, constitutive relations, and equilibrium partition to all orders in derivative expansion. We also devise a mechanism to introduce $U(1)$ anomaly in even dimensional Galilean theories using light cone reduction, and study its effect on the constitutive relations of a Galilean Fluid.

  3. Axon and muscle spindle hyperplasia in the myostatin null mouse.

    Science.gov (United States)

    Elashry, Mohamed I; Otto, Anthony; Matsakas, Antonios; El-Morsy, Salah E; Jones, Lisa; Anderson, Bethan; Patel, Ketan

    2011-02-01

    Germline deletion of the myostatin gene results in hyperplasia and hypertrophy of the tension-generating (extrafusal) fibres in skeletal muscle. As this gene is expressed predominantly in myogenic tissues it offers an excellent model with which to investigate the quantitative relationship between muscle and axonal development. Here we show that skeletal muscle hyperplasia in myostatin null mouse is accompanied by an increase in nerve fibres in major nerves of both the fore- and hindlimbs. We show that axons within these nerves undergo hypertrophy. Furthermore, we provide evidence that the age-related neural atrophic process is delayed in the absence of myostatin. Finally, we show that skeletal muscle hyperplasia in the myostatin null mouse is accompanied by an increase in the number of muscle spindles (also called stretch receptors or proprioceptors). However, our work demonstrates that the mechanisms regulating intrafusal fibre hyperplasia and hypertrophy differ from those that control the aetiology of extrafusal fibres.

  4. Nonparametric Regression Estimation for Multivariate Null Recurrent Processes

    Directory of Open Access Journals (Sweden)

    Biqing Cai

    2015-04-01

    Full Text Available This paper discusses nonparametric kernel regression with the regressor being a \\(d\\-dimensional \\(\\beta\\-null recurrent process in presence of conditional heteroscedasticity. We show that the mean function estimator is consistent with convergence rate \\(\\sqrt{n(Th^{d}}\\, where \\(n(T\\ is the number of regenerations for a \\(\\beta\\-null recurrent process and the limiting distribution (with proper normalization is normal. Furthermore, we show that the two-step estimator for the volatility function is consistent. The finite sample performance of the estimate is quite reasonable when the leave-one-out cross validation method is used for bandwidth selection. We apply the proposed method to study the relationship of Federal funds rate with 3-month and 5-year T-bill rates and discover the existence of nonlinearity of the relationship. Furthermore, the in-sample and out-of-sample performance of the nonparametric model is far better than the linear model.

  5. Advances in corneal topography measurements with conical null-screens

    Science.gov (United States)

    Campos-García, Manuel; Cossio-Guerrero, Cesar; Huerta-Carranza, Oliver; Moreno-Oliva, Víctor I.

    2015-09-01

    In this work we report the design of a null-screen for corneal topography. To avoid the difficulties in the alignment of the test system due to the face contour (eyebrows, nose, or eyelids), we design a conical null-screen with a novel radial points distribution drawn on it in such a way that its image, which is formed by reflection on the test surface, becomes an exact array of circular spots if the surface is perfect. Additionally, an algorithm to compute the sagittal and meridional radii of curvature for the corneal surface is presented. The sagittal radius is obtained from the surface normal, and the meridional radius is calculated from a function fitted to the derivative of the sagittal curvature by using the surfacenormals raw data. Experimental results for the testing a calibration spherical surface are shown. Also, we perform some corneal topography measurements.

  6. Defocusing of null rays in infinite derivative gravity

    Science.gov (United States)

    Conroy, Aindriú; Koshelev, Alexey S.; Mazumdar, Anupam

    2017-01-01

    Einstein's General theory of relativity permits spacetime singularities, where null geodesic congruences focus in the presence of matter, which satisfies an appropriate energy condition. In this paper, we provide a minimal defocusing condition for null congruences without assuming any ansatz-dependent background solution. The two important criteria are: (1) an additional scalar degree of freedom, besides the massless graviton must be introduced into the spacetime; and (2) an infinite derivative theory of gravity is required in order to avoid tachyons or ghosts in the graviton propagator. In this regard, our analysis strengthens earlier arguments for constructing non-singular bouncing cosmologies within an infinite derivative theory of gravity, without assuming any ansatz to solve the full equations of motion.

  7. Averaged null energy condition in Loop Quantum Cosmology

    CERN Document Server

    Li, Li-Fang

    2008-01-01

    Wormhole and time machine are very interesting objects in general relativity. However, they need exotic matters which are impossible in classical level to support them. But if we introduce the quantum effects of gravity into the stress-energy tensor, these peculiar objects can be constructed self-consistently. Fortunately, loop quantum cosmology (LQC) has the potential to serve as a bridge connecting the classical theory and quantum gravity. Therefore it provides a simple way for the study of quantum effect in the semiclassical case. As is well known, loop quantum cosmology is very successful to deal with the behavior of early universe. In the early stage, if taken the quantum effect into consideration, inflation is natural because of the violation of every kind of local energy conditions. Similar to the inflationary universe, the violation of the averaged null energy condition is the necessary condition for the traversable wormholes. In this paper, we investigate the averaged null energy condition in LQC in ...

  8. Analysis of nulling phase functions suitable to image plane coronagraphy

    CERN Document Server

    Henault, Francois; Verinaud, Christophe

    2016-01-01

    Coronagraphy is a very efficient technique for identifying and characterizing extra-solar planets orbiting in the habitable zone of their parent star, especially when used in a space environment. An important family of coronagraphs is based on phase plates located at an intermediate image plane of the optical system, that spread the starlight outside the "Lyot" exit pupil plane of the instrument. In this communication we present a set of candidate phase functions generating a central null at the Lyot plane, and study how it propagates to the image plane of the coronagraph. These functions include linear azimuthal phase ramps (the well-known optical vortex), azimuthally cosine-modulated phase profiles, and circular phase gratings. Numerical simulations of the expected null depth, inner working angle, sensitivity to pointing errors, effect of central obscuration located at the pupil or image planes, and effective throughput including image mask and Lyot stop transmissions are presented and discussed. The prelim...

  9. Null fluids: A new viewpoint of Galilean fluids

    Science.gov (United States)

    Banerjee, Nabamita; Dutta, Suvankar; Jain, Akash

    2016-05-01

    In this article, we study a Galilean fluid with a conserved U (1 ) current up to anomalies. We construct a relativistic system, which we call a null fluid and show that it is in one-to-one correspondence with a Galilean fluid living in one lower dimension. The correspondence is based on light cone reduction, which is known to reduce the Poincaré symmetry of a theory to Galilean in one lower dimension. We show that the proposed null fluid and the corresponding Galilean fluid have exactly same symmetries, thermodynamics, constitutive relations, and equilibrium partition to all orders in the derivative expansion. We also devise a mechanism to introduce U (1 ) anomaly in even dimensional Galilean theories using light cone reduction, and study its effect on the constitutive relations of a Galilean fluid.

  10. Quantization of black hole entropy from unstable circular null geodesics

    Science.gov (United States)

    Wei, Shao-Wen; Liu, Yu-Xiao; Fu, Chun-E.

    2016-04-01

    The quasinormal mode frequencies can be understood from the massless particles trapped at the unstable circular null geodesics and slowly leaking out to infinity. Based on this viewpoint, in this paper, we semiclassically construct the entropy spectrum of the static and stationary black holes from the null geodesics. The result shows that the spacing of the entropy spectrum only depends on the property of the black hole in the eikonal limit. Moreover, for a black hole far from the extremal case, the spacing is found to be smaller than 2πħ for any dimension, which is very different from the result of the previous work by using the usual quasinormal mode frequencies.

  11. Do electromagnetic waves always propagate along null geodesics?

    CERN Document Server

    Asenjo, Felipe A

    2016-01-01

    We find exact solutions to Maxwell equations written in terms of four-vector potentials in non--rotating, as well as in G\\"odel and Kerr spacetimes. Exact electromagnetic waves solutions are written on given gravitational field backgrounds where they evolve. We find that in non--rotating spherical symmetric spacetimes, electromagnetic plane waves travel along null geodesics. However, electromagnetic plane waves on G\\"odel and Kerr spacetimes do not exhibit that behavior.

  12. Three-dimensional magnetic reconnection through a moving magnetic null

    OpenAIRE

    Lukin, V. S.; Linton, M. G.

    2011-01-01

    A computational study of three-dimensional magnetic reconnection between two flux ropes through a moving reconnection site is presented. The configuration is considered in the context of two interacting spheromaks constrained by a perfectly conducting cylindrical boundary and oriented to form a single magnetic field null at its center. The initial magnetic field configuration is embedded into a uniform thermal plasma and is unstable to tilting. As the sphe...

  13. Three-dimensional magnetic reconnection through a moving magnetic null

    OpenAIRE

    Lukin, V. S.; Linton, M. G.

    2011-01-01

    A computational study of three-dimensional magnetic reconnection between two flux ropes through a moving reconnection site is presented. The configuration is considered in the context of two interacting spheromaks constrained by a perfectly conducting cylindrical boundary and oriented to form a single magnetic field null at its center. The initial magnetic field configuration is embedded into a uniform thermal plasma and is unstable to tilting. As the spheromaks tilt, their magnetic fi...

  14. (abstract) Ulysses Observations of Magnetic Nulls in the Solar Wind

    Science.gov (United States)

    Winterhalter, D.; Murphy, N.; Tsurutani, B. T.; Smith, E. J.; Balogh, A.; Erdos, G.

    1993-01-01

    High time resolution magnetic field measurements (1 vector/s) at radial distances out to 5.3 AU and heliographic latitudes from 0(deg) to > 35(deg) S reveal the presence of solitary pulses lasting tens of seconds in which the field magnitude approaches or reaches zero. The properties of these nulls, their spatial distribution and relation to solar wind structures and to similar-apppearing interplanetary and magnetospheric impulses will be discussed.

  15. Energy dissipation in magnetic null points at kinetic scales

    OpenAIRE

    Olshevsky, Vyacheslav; Divin, Andrey; Eriksson, Elin; Markidis, Stefano; Lapenta, Giovanni

    2015-01-01

    We use kinetic particle-in-cell and MHD simulations supported by an observational data set to investigate magnetic reconnection in clusters of null points in space plasma. The magnetic configuration under investigation is driven by fast adiabatic flux rope compression that dissipates almost half of the initial magnetic field energy. In this phase powerful currents are excited producing secondary instabilities, and the system is brought into a state of "intermittent turbulence" within a few io...

  16. 4-dimensional spacetimes from 2-dimensional conformal null data

    Science.gov (United States)

    Goswami, Rituparno; Ellis, George F. R.

    2017-03-01

    In this paper we investigate whether the holographic principle proposed in string theory has a classical counterpart in general relativity theory. We show that there is a partial correspondence: at least in the case of vacuum Petrov type D spacetimes that admit a non-trivial Killing tensor, which encompass all the astrophysical black hole spacetimes, there exists a one-to-one correspondence between gravity in bulk and a 2-dimensional classical conformal scalar field on a null boundary.

  17. Scalar $QCD_{4}$ on the null-plane

    CERN Document Server

    Casana, R; Zambrano, G E R

    2008-01-01

    We have studied the null-plane hamiltonian structure of the free Yang-Mills fields and the scalar chromodynamics ($SQCD_{4}$). Following the Dirac's procedure for constrained systems we have performed a detailed analysis of the constraint structure of both models and we give the generalized Dirac brackets for the physical variables. In the free Yang-Mills case, using the correspondence principle in the Dirac's brackets we obtain the same commutators present in the literature.

  18. Null controllability for linear parabolic cascade systems with interior degeneracy

    Directory of Open Access Journals (Sweden)

    Idriss Boutaayamou

    2016-11-01

    Full Text Available We study the null controllability problem for linear degenerate parabolic systems with one control force through Carleman estimates for the associated adjoint problem. The novelty of this article is that for the first time it is considered a problem with an interior degeneracy and a control set that only requires to contain an interval lying on one side of the degeneracy points. The obtained result improves and complements a number of earlier works. As a consequence, observability inequalities are established.

  19. Fresnel rhombs as achromatic phase shifters for infrared nulling interferometry

    OpenAIRE

    Mawet, D.; Hanot, Charles; Lenaers, C.; Riaud, Pierre; Defrere, Denis; Vandormael; Loicq, Jerôme; Fleury, K.; Plesseria, Jean-Yves; Surdej, Jean; Habraken, Serge

    2007-01-01

    We propose a new family of achromatic phase shifters for infrared nulling interferometry. These key optical components can be seen as optimized Fresnel rhombs, using the total internal reflection phenomenon, modulated or not. The total internal reflection indeed comes with a phase shift between the polarization components of the incident light. We propose a solution to implement this vectorial phase shift between interferometer arms to provide the destructive interference process needed to di...

  20. Nulling interferometry for exoplanet detection using polarization properties

    OpenAIRE

    Spronck, J.; Pereira, S.F.; Braat, J.J.M.

    2006-01-01

    We present a new type of nulling interferometer that makes use of polarization properties to have on-axis destructive interference. The proposed design, which only involves commercial components and no achromatic device, is also suitable for internal modulation. This type of interferometer should enable a high rejection ratio in a theoretically unlimited spectral band. We implemented that concept on a two-beam white-light interferometer and we present here the first experimental results

  1. Null-Tetradic treatment of the Relativistic Dynamics (II)

    Science.gov (United States)

    Gottlieb, I.; Maftei, Gh.

    The authors apply the Null-tetradic formalism as was given in the book by Kramer, Stephani, Herlt, Mac-Callum, Exact Solutions (1980) to some of the chapters of General Relativity which were not examined in the book above and such a way make a connection with another classic book in General Relativity: that of Landau and Lifchitz, Theorie des champs, Ed. Mir, Moscou (1989).

  2. Null controllability for a parabolic-elliptic coupled system

    CERN Document Server

    Fernández-Cara, E; de Menezes, S B

    2012-01-01

    In this paper, we prove the null controllability of some parabolic-elliptic systems. The control is distributed, locally supported in space and appears only in one PDE. The arguments rely on fixed-point reformulation and suitable Carleman estimates for the solutions to the adjoint system. Under appropriate assumptions, we also prove that the solution can be obtained as the asymptotic limit of some similar parabolic systems.

  3. Influence of metabolic genotypes on biomarkers of exposure to 1,3-butadiene in humans.

    Science.gov (United States)

    Fustinoni, Silvia; Soleo, Leonardo; Warholm, Margareta; Begemann, Petra; Rannug, Agneta; Neumann, Hans-G; Swenberg, James A; Vimercati, Luigi; Colombi, Antonio

    2002-10-01

    Carcinogenicity of 1,3-butadiene (BD) has been linked to its metabolic activation of genotoxic epoxides. The inherited variations in the activity of BD-metabolizing enzymes may be responsible for individual differences that modulate the effects of BD exposure. In this study, 40 Italian subjects (30 BD-exposed workers and 10 clerks) were investigated to evaluate the role of genetic polymorphism of cytochromes P450 2E1, microsomal epoxide hydrolase, glutathione transferases GSTM1, GSTP1, GSTT1, and alcohol dehydrogenase, on urinary N-acetyl-S-(3,4-hydroxybutyl)-L-cysteine (MI) and hemoglobin N-(2,3,4-trihydroxybutyl)-valine adducts (THBVal). Median urinary MI and THBVal levels were 1.71 mg/g creatinine and 37.0 pmol/g globin in BD-exposed workers (exposure range, 4-201 microg/m(3)) and 1.42 mg/g creatinine and 35.3 pmol/g globin in unexposed subjects. No difference between the two groups was observed. Among all subjects, MI and THBVal levels were significantly correlated (r = 0.333). Smoking positively influenced the formation of THBVal. Higher THBVal levels were found in subjects with GSTM1 null and GSTT1 null genotypes; borderline influences were also noticed for CYP2E1(G(-35)T). An additive effect of combined polymorphisms for CYP2E1, GSTM1, and GSTT1 genes on the THBVal levels was suggested. A multiple linear regression analysis, where each factor contributed significantly, correlated THBVal levels with smoking, CYP2E1(G(-35)T), GSTT1, and GSTM1 genotypes (r = 0.698). Our results indicate that the THBVal level is influenced by genotypes, and that the analysis of combined polymorphisms may be the key to a better understanding of the role played by polymorphism of BD-metabolizing enzymes.

  4. Role of glutathione S transferase polymorphism in COPD with special reference to peoples living in the vicinity of the open cast coal mine of Assam.

    Directory of Open Access Journals (Sweden)

    Tapan Dey

    Full Text Available BACKGROUND: COPD may develop due to variation in the functioning of antioxidants along with smoking and environmental factors in genetically susceptible individuals. Since there are different views about the antioxidants responsible for detoxifying xenobiotic compound in the human body whose functional variation may lead to obstructive disease, this associative study has been taken up between GST gene polymorphism and COPD in populations exposed to coal dusts. METHODS: Genotypes of the 70 COPD patients and 85 non COPD patients were determined by PCR based methods followed by multiplex PCR of GSTT1 and GSTM1 genes taking albumin gene as a control. Suspended particulate analyses were determined through the Respirable Dust sampler along with the FTIR analysis of the dust samples from the glass microfiber filters. RESULTS: Dust sampling analysis reveals higher level of respirable suspended particulate matter, non respirable particulate matter, SO2 and NO2 present in air of the study site. FTIR analysis also suggests a higher concentration of organic silicone and aliphatic C-F compounds present in air of the study site and when spirometry was done, low lung function was observed among most of the subjects. GSTM1 null type was significantly associated with low lung function in smoker groups and the presence of at least one active allele (either GSTM1/GSTT1 seemed to have a protective role in the development of COPD. CONCLUSIONS: GSTM1 (null genotype appeared to be a risk factor for lower lung function in smokers living in the vicinity of coal mines. Apart from polluted environment and genetic susceptibility, mixed coal dust exposure rich in organic silicone and aliphatic C-F compounds also appears to be a factor for the low lung function.

  5. Gene co-expression analyses differentiate networks associated with diverse cancers harbouring TP53 missense or null mutations

    Directory of Open Access Journals (Sweden)

    Kathleen Oros Klein

    2016-08-01

    Full Text Available In a variety of solid cancers, missense mutations in the well-established TP53 tumour suppressor gene may lead to presence of a partially-functioning protein molecule, whereas mutations affecting the protein encoding reading frame, often referred to as null mutations, result in the absence of p53 protein. Both types of mutations have been observed in the same cancer type. As the resulting tumour biology may be quite different between these two groups, we used RNA-sequencing data from The Cancer Genome Atlas (TCGA from four different cancers with poor prognosis, namely ovarian, breast, lung and skin cancers, to compare the patterns of co-expression of genes in tumours grouped according to their TP53 missense or null mutation status. We used Weighted Gene Coexpression Network analysis (WGCNA and a new test statistic built on differences between groups in the measures of gene connectivity. For each cancer, our analysis identified a set of genes showing differential coexpression patterns between the TP53 missense- and null mutation-carrying groups that was robust to the choice of the tuning parameter in WGCNA. After comparing these sets of genes across the four cancers, one gene (KIR3DL2 consistently showed differential coexpression patterns between the null and missense groups. KIR3DL2 is known to play an important role in regulating the immune response, which is consistent with our observation that this gene’s strongly-correlated partners implicated many immune-related pathways. Examining mutation-type-related changes in correlations between sets of genes may provide new insight into tumour biology.

  6. Zero emission city. Preliminary study; Null-Emissions-Stadt. Sondierungsstudie

    Energy Technology Data Exchange (ETDEWEB)

    Diefenbach, N.; Enseling, A.; Werner, P.; Flade, A.; Greiff, R.; Hennings, D.; Muehlich, E.; Wullkopf, U.; Sturm, P.; Kieslich, W.; Born, R.; Grossklos, M.; Hatteh, R.; Mueller, K.; Ratschow, A.; Valouch-Fornoff, C.

    2002-10-01

    The idea of a 'zero emission city' is investigated by the Institut Wohnen und Umwelt on behalf of the Federal Minister of Education and Research. After describing the current situation and defining the key parameters of a 'zero emission city', settlement structures, power supply, production processes and transportation are analyzed and linked with the communal action level to obtain a framework for research, activities and actions. The study ends with recommendations for a research programme 'zero emission city'. (orig.) [German] Die von den Staedten der Industrielaender ausgehenden Emissionen stellen im Hinblick auf die globalen Belastungen wie z.B. Treibhauseffekt, Ozonabbau und Versauerung das Hauptproblem dar. Aus diesem Grunde bietet es sich an, den Gedanken der 'Null-Emissions-Stadt', der Vision einer moeglichst emissionsfreien Stadt, aufzugreifen und auf seine Tragfaehigkeit fuer innovative Handlungsmodelle forschungsstrategisch zu ueberpruefen. Das Bundesministerium fuer Bildung und Forschung hat das Institut Wohnen und Umwelt beauftragt, in einer Sondierungsstudie dieser Fragestellung nachzugehen. Nach der Festlegung der Ausgangsbedingungen und Eckpunkte der Vision 'Null-Emissions-Stadt' und der Analyse der vier Handlungsfelder Siedlungsstrukturen, Energieversorgung, Produktionsprozesse (Kreislaufwirtschaft) und Verkehr werden diese aufgegriffen und mit der kommunalen Handlungsebene verknuepft und zu einem Forschungs-, Handlungs- und moeglichen Aktionsrahmen zusammengefuegt. Die Studie schliesst mit Hinweisen fuer die Gestaltung eines Forschungsprogramms 'Null-Emissions-Stadt'. (orig.)

  7. Retarded Fields of Null Particles and the Memory Effect

    CERN Document Server

    Tolish, Alexander

    2014-01-01

    We consider the retarded solution to the scalar, electromagnetic, and linearized gravitational field equations in Minkowski spacetime, with source given by a particle moving on a null geodesic. In the scalar case and in the Lorenz gauge in the electromagnetic and gravitational cases, the retarded integral over the infinite past of the source does not converge as a distribution, so we cut off the null source suitably at a finite time $t_0$ and then consider two different limits: (i) the limit as the observation point goes to null infinity at fixed $t_0$, from which the ``$1/r$'' part of the fields can be extracted and (ii) the limit $t_0 \\to - \\infty$ at fixed ``observation point.'' The limit (i) gives rise to a ``velocity kick'' on distant test particles in the scalar and electromagnetic cases, and it gives rise to a ``memory effect'' (i.e., a permanent change in relative separation of two test particles) in the linearized gravitational case, in agreement with previous analyses. Although the second limit does...

  8. Evaluating thermoregulation in reptiles: an appropriate null model.

    Science.gov (United States)

    Christian, Keith A; Tracy, Christopher R; Tracy, C Richard

    2006-09-01

    Established indexes of thermoregulation in ectotherms compare body temperatures of real animals with a null distribution of operative temperatures from a physical or mathematical model with the same size, shape, and color as the actual animal but without mass. These indexes, however, do not account for thermal inertia or the effects of inertia when animals move through thermally heterogeneous environments. Some recent models have incorporated body mass, to account for thermal inertia and the physiological control of warming and cooling rates seen in most reptiles, and other models have incorporated movement through the environment, but none includes all pertinent variables explaining body temperature. We present a new technique for calculating the distribution of body temperatures available to ectotherms that have thermal inertia, random movements, and different rates of warming and cooling. The approach uses a biophysical model of heat exchange in ectotherms and a model of random interaction with thermal environments over the course of a day to create a null distribution of body temperatures that can be used with conventional thermoregulation indexes. This new technique provides an unbiased method for evaluating thermoregulation in large ectotherms that store heat while moving through complex environments, but it can also generate null models for ectotherms of all sizes.

  9. "Time sweet time": circadian characterization of galectin-1 null mice

    Directory of Open Access Journals (Sweden)

    Rabinovich Gabriel A

    2010-04-01

    Full Text Available Abstract Background Recent evidence suggests a two-way interaction between the immune and circadian systems. Circadian control of immune factors, as well as the effect of immunological variables on circadian rhythms, might be key elements in both physiological and pathological responses to the environment. Among these relevant factors, galectin-1 is a member of a family of evolutionarily-conserved glycan-binding proteins with both extracellular and intracellular effects, playing important roles in immune cell processes and inflammatory responses. Many of these actions have been studied through the use of mice with a null mutation in the galectin-1 (Lgals1 gene. To further analyze the role of endogenous galectin-1 in vivo, we aimed to characterize the circadian behavior of galectin-1 null (Lgals1-/- mice. Methods We analyzed wheel-running activity in light-dark conditions, constant darkness, phase responses to light pulses (LP at circadian time 15, and reentrainment to 6 hour shifts in light-dark schedule in wild-type (WT and Lgals1-/- mice. Results We found significant differences in free-running period, which was longer in mutant than in WT mice (24.02 vs 23.57 h, p alpha (14.88 vs. 12.35 circadian h, p Conclusions Given the effect of a null mutation on circadian period and entrainment, we indicate that galectin-1 could be involved in the regulation of murine circadian rhythmicity. This is the first study implicating galectin-1 in the mammalian circadian system.

  10. Non-null annular subaperture stitching interferometry for aspheric test

    Science.gov (United States)

    Zhang, Lei; Liu, Dong; Shi, Tu; Yang, Yongying; Chong, Shiyao; Miao, Liang; Huang, Wei; Shen, Yibing; Bai, Jian

    2015-10-01

    A non-null annular subaperture stitching interferometry (NASSI), combining the subaperture stitching idea and non-null test method, is proposed for steep aspheric testing. Compared with standard annular subaperture stitching interferometry (ASSI), a partial null lens (PNL) is employed as an alternative to the transmission sphere, to generate different aspherical wavefronts as the references. The coverage subaperture number would thus be reduced greatly for the better performance of aspherical wavefronts in matching the local slope of aspheric surfaces. Instead of various mathematical stitching algorithms, a simultaneous reverse optimizing reconstruction (SROR) method based on system modeling and ray tracing is proposed for full aperture figure error reconstruction. All the subaperture measurements are simulated simultaneously with a multi-configuration model in a ray-tracing program, including the interferometric system modeling and subaperture misalignments modeling. With the multi-configuration model, full aperture figure error would be extracted in form of Zernike polynomials from subapertures wavefront data by the SROR method. This method concurrently accomplishes subaperture retrace error and misalignment correction, requiring neither complex mathematical algorithms nor subaperture overlaps. A numerical simulation exhibits the comparison of the performance of the NASSI and standard ASSI, which demonstrates the high accuracy of the NASSI in testing steep aspheric. Experimental results of NASSI are shown to be in good agreement with that of Zygo® VerifireTM Asphere interferometer.

  11. High-power, null-type, inverted pendulum thrust stand.

    Science.gov (United States)

    Xu, Kunning G; Walker, Mitchell L R

    2009-05-01

    This article presents the theory and operation of a null-type, inverted pendulum thrust stand. The thrust stand design supports thrusters having a total mass up to 250 kg and measures thrust over a range of 1 mN to 5 N. The design uses a conventional inverted pendulum to increase sensitivity, coupled with a null-type feature to eliminate thrust alignment error due to deflection of thrust. The thrust stand position serves as the input to the null-circuit feedback control system and the output is the current to an electromagnetic actuator. Mechanical oscillations are actively damped with an electromagnetic damper. A closed-loop inclination system levels the stand while an active cooling system minimizes thermal effects. The thrust stand incorporates an in situ calibration rig. The thrust of a 3.4 kW Hall thruster is measured for thrust levels up to 230 mN. The uncertainty of the thrust measurements in this experiment is +/-0.6%, determined by examination of the hysteresis, drift of the zero offset and calibration slope variation.

  12. Variational principle for gravity with null and non-null boundaries: a unified boundary counter-term

    Energy Technology Data Exchange (ETDEWEB)

    Parattu, Krishnamohan; Chakraborty, Sumanta; Padmanabhan, T. [IUCAA, Post Bag 4, Pune (India)

    2016-03-15

    It is common knowledge that the Einstein-Hilbert action does not furnish a well-posed variational principle. The usual solution to this problem is to add an extra boundary term to the action, called a counter-term, so that the variational principle becomes well-posed. When the boundary is spacelike or timelike, the Gibbons-Hawking-York counter-term is the most widely used. For null boundaries, we had proposed a counter-term in a previous paper. In this paper, we extend the previous analysis and propose a counter-term that can be used to eliminate variations of the ''off-the-surface'' derivatives of the metric on any boundary, regardless of its spacelike, timelike or null nature. (orig.)

  13. Variational Principle for Gravity with Null and Non-null boundaries: A Unified Boundary Counter-term

    CERN Document Server

    Parattu, Krishnamohan; Padmanabhan, T

    2016-01-01

    It is common knowledge that the Einstein-Hilbert action does not furnish a well-posed variational principle. The usual solution to this problem is to add an extra boundary term to the action, called a counter-term, so that the variational principle becomes well-posed. When the boundary is spacelike or timelike, the Gibbons-Hawking-York counter-term is the most widely used. For null boundaries, we had proposed a counter-term in a previous paper. In this paper, we extend the previous analysis and propose a counter-term that can be used to eliminate variations of the "off-the-surface" derivatives of the metric on any boundary, regardless of its spacelike, timelike or null nature.

  14. The gravitational exclusion principle and null states in anti-de Sitter space

    Energy Technology Data Exchange (ETDEWEB)

    Castro, Alejandra; Maloney, Alexander [Department of Physics, McGill University, Montreal, QC (Canada); Hartman, Thomas [School of Natural Sciences, Institute for Advanced Study, Princeton, NJ (United States)

    2011-10-07

    The holographic principle implies a vast reduction in the number of degrees of freedom of quantum gravity. This idea can be made precise in AdS{sub 3}, where the the stringy or gravitational exclusion principle asserts that certain perturbative excitations are not present in the exact quantum spectrum. We show that this effect is visible directly in the bulk gravity theory: the norm of the offending linearized state is zero or negative. When the norm is negative, the theory is signalling its own breakdown as an effective field theory; this provides a perturbative bulk explanation for the stringy exclusion principle. When the norm vanishes the bulk state is null rather than physical. This implies that certain non-trivial diffeomorphisms must be regarded as gauge symmetries rather than spectrum-generating elements of the asymptotic symmetry group. This leads to subtle effects in the computation of one-loop determinants for Einstein gravity, higher spin theories and topologically massive gravity in AdS{sub 3}. In particular, heat kernel methods do not capture the correct spectrum of a theory with null states. Communicated by S Ross

  15. Null Models and Modularity Based Community Detection in Multi-Layer Networks

    CERN Document Server

    Paul, Subhadeep

    2016-01-01

    Multi-layer networks are networks on a set of entities (nodes) with multiple types of relations (edges) among them where each type of relation/interaction is represented as a network layer. As with single layer networks, community detection is an important task in multi-layer networks. A large group of popular community detection methods in networks are based on optimizing a quality function known as the modularity score, which is a measure of presence of modules or communities in networks. Hence a first step in community detection is defining a suitable modularity score that is appropriate for the network in question. Here we introduce several multi-layer network modularity measures under different null models of the network, motivated by empirical observations in networks from a diverse field of applications. In particular we define the multi-layer configuration model, the multi-layer expected degree model and their various modifications as null models for multi-layer networks to derive different modulariti...

  16. Achieving Data Privacy through Secrecy Views and Null-Based Virtual Updates

    CERN Document Server

    Bertossi, Leopoldo

    2011-01-01

    There may be sensitive information in a relational database, and we might want to keep it hidden from a user or group thereof. In this work, sensitive data is characterized as the contents of a set of secrecy views. For a user without permission to access that sensitive data, the database instance he queries is updated to make the contents of the views empty or contain only tuples with null values. In particular, if this user poses a query about any of these views, no meaningful information is returned. Since the database is not expected to be physically changed to produce this result, the updates are only virtual. And also minimal in a precise way. These minimal updates are reflected in the secrecy view contents, and also in the fact that query answers, while being privacy preserving, are also maximally informative. Virtual updates are based on the use of null values as used in the SQL standard. We provide the semantics of secrecy views and the virtual updates. The different ways in which the underlying data...

  17. Vacuum Nuller Testbed Performance, Characterization and Null Control

    Science.gov (United States)

    Lyon, R. G.; Clampin, M.; Petrone, P.; Mallik, U.; Madison, T.; Bolcar, M.; Noecker, C.; Kendrick, S.; Helmbrecht, M. A.

    2011-01-01

    The Visible Nulling Coronagraph (VNC) can detect and characterize exoplanets with filled, segmented and sparse aperture telescopes, thereby spanning the choice of future internal coronagraph exoplanet missions. NASA/Goddard Space Flight Center (GSFC) has developed a Vacuum Nuller Testbed (VNT) to advance this approach, and assess and advance technologies needed to realize a VNC as a flight instrument. The VNT is an ultra-stable testbed operating at 15 Hz in vacuum. It consists of a MachZehnder nulling interferometer; modified with a "W" configuration to accommodate a hexpacked MEMS based deformable mirror (DM), coherent fiber bundle and achromatic phase shifters. The 2-output channels are imaged with a vacuum photon counting camera and conventional camera. Error-sensing and feedback to DM and delay line with control algorithms are implemented in a real-time architecture. The inherent advantage of the VNC is that it is its own interferometer and directly controls its errors by exploiting images from bright and dark channels simultaneously. Conservation of energy requires the sum total of the photon counts be conserved independent of the VNC state. Thus sensing and control bandwidth is limited by the target stars throughput, with the net effect that the higher bandwidth offloads stressing stability tolerances within the telescope. We report our recent progress with the VNT towards achieving an incremental sequence of contrast milestones of 10(exp 8) , 10(exp 9) and 10(exp 10) respectively at inner working angles approaching 2A/D. Discussed will be the optics, lab results, technologies, and null control. Shown will be evidence that the milestones have been achieved.

  18. DBI Genesis: An Improved Violation of the Null Energy Condition

    CERN Document Server

    Hinterbichler, Kurt; Khoury, Justin; Miller, Godfrey E J

    2013-01-01

    We show that the DBI conformal galileons, derived from the world-volume theory of a 3-brane moving in an AdS bulk, admit a background, stable under quantum corrections, which violates the Null Energy Condition (NEC). The perturbations around this background are stable and propagate subluminally. Unlike other known examples of NEC violation, such as ghost condensation and conformal galileons, this theory also admits a stable, Poincare-invariant vacuum, with a Lorentz-invariant S-matrix satisfying standard analyticity conditions. Like conformal galileons, perturbations around deformations of the Poincare invariant vacuum propagate superluminally.

  19. A Visualization of Null Geodesics for the Bonnor Massive Dipole

    CERN Document Server

    Oliva-Mercado, Guillermo Andree; Cordero-García, Iván; Frutos-Alfaro, Francisco

    2015-01-01

    In this work we simulate null geodesics for the Bonnor massive dipole metric by implementing a symbolic-numerical algorithm in Sage and Python. This program is also capable of visualizing in 3D, in principle, the geodesics for any given metric. Geodesics are launched from a common point, collectively forming a cone of light beams, simulating a solid-angle section of a point source in front of a massive object with a magnetic field. Parallel light beams also were considered, and their bending due to the curvature of the space-time was simulated.

  20. Conformal symmetry wormholes and the null energy condition

    CERN Document Server

    Kuhfittig, Peter K F

    2016-01-01

    In this paper we seek a relationship between the assumption of conformal symmetry and the exotic matter needed to hold a wormhole open. By starting with a Morris-Thorne wormhole having a constant energy density, it is shown that the conformal factor provides the extra degree of freedom sufficient to account for the exotic matter. The same holds for Morris-Thorne wormholes in a noncommutative-geometry setting. Applied to thin shells, there would exist a radius that results in a wormhole with positive surface density and negative surface pressure and which violates the null energy condition on the thin shell.

  1. Why is the null HBT result at RHIC so interesting?

    CERN Document Server

    Gyulassy, M

    2003-01-01

    Pion interferometry (HBT of A+A) data have posed a thorn in the theoretical interpretation of AA collisions at RHIC (sq root s = 130 AGeV). How can R sub o sub u sub t approx R sub s sub i sub d sub e approx R sub l sub o sub n sub g and remain so between AGS and RHIC? Where is the QGP Stall? Can elephants hide along the x sub 0 sup + dimension? We rummage old hydrodynamic scenarios and uncover some previously ignored NULL solutions. (author)

  2. A visualization of null geodesics for the bonnor massive dipole

    Directory of Open Access Journals (Sweden)

    G. Andree Oliva Mercado

    2015-08-01

    Full Text Available In this work we simulate null geodesics for the Bonnor massive dipole metric by implementing a symbolic-numerical algorithm in Sage and Python. This program is also capable of visualizing in 3D, in principle, the geodesics for any given metric. Geodesics are launched from a common point, collectively forming a cone of light beams, simulating a solid-angle section of a point source in front of a massive object with a magnetic field. Parallel light beams also were considered, and their bending due to the curvature of the space-time was simulated.

  3. An Efficient Null Model for Conformational Fluctuations in Proteins

    DEFF Research Database (Denmark)

    Harder, Tim Philipp; Borg, Mikael; Bottaro, Sandro

    2012-01-01

    limited to comparatively short timescales. TYPHON is a probabilistic method to explore the conformational space of proteins under the guidance of a sophisticated probabilistic model of local structure and a given set of restraints that represent nonlocal interactions, such as hydrogen bonds or disulfide...... bridges. The choice of the restraints themselves is heuristic, but the resulting probabilistic model is well-defined and rigorous. Conceptually, TYPHON constitutes a null model of conformational fluctuations under a given set of restraints. We demonstrate that TYPHON can provide information...

  4. Scale anomalies imply violation of the averaged null energy condition

    CERN Document Server

    Visser, M

    1994-01-01

    Considerable interest has recently been expressed regarding the issue of whether or not quantum field theory on a fixed but curved background spacetime satisfies the averaged null energy condition (ANEC). A comment by Wald and Yurtsever [Phys. Rev. D43, 403 (1991)] indicates that in general the answer is no. In this note I explore this issue in more detail, and succeed in characterizing a broad class of spacetimes in which the ANEC is guaranteed to be violated. Finally, I add some comments regarding ANEC violation in Schwarzschild spacetime.

  5. Midinfrared broadband achromatic astronomical beam combiner for nulling interferometry.

    Science.gov (United States)

    Hsiao, Hsien-kai; Winick, Kim A; Monnier, John D

    2010-12-10

    Integrated optic beam combiners offer many advantages over conventional bulk optic implementations for astronomical imaging. To our knowledge, integrated optic beam combiners have only been demonstrated at operating wavelengths below 4 μm. Operation in the midinfrared wavelength region, however, is highly desirable. In this paper, a theoretical design technique based on three coupled waveguides is developed to achieve fully achromatic, broadband, polarization-insensitive, lossless beam combining. This design may make it possible to achieve the very deep broadband nulls needed for exoplanet searching.

  6. MicroRNA Dysregulation in Liver and Pancreas of CMP-Neu5Ac Hydroxylase Null Mice Disrupts Insulin/PI3K-AKT Signaling

    Directory of Open Access Journals (Sweden)

    Deug-Nam Kwon

    2014-01-01

    Full Text Available CMP-Neu5Ac hydroxylase (Cmah-null mice fed with a high-fat diet develop fasting hyperglycemia, glucose intolerance, and pancreatic β-cell dysfunction and ultimately develop characteristics of type 2 diabetes. The precise metabolic role of the Cmah gene remains poorly understood. This study was designed to investigate the molecular mechanisms through which microRNAs (miRNAs regulate type 2 diabetes. Expression profiles of miRNAs in Cmah-null mouse livers were compared to those of control mouse livers. Liver miFinder miRNA PCR arrays (n=6 showed that eight miRNA genes were differentially expressed between the two groups. Compared with controls, seven miRNAs were upregulated and one miRNA was downregulated in Cmah-null mice. Specifically, miR-155-5p, miR-425-5p, miR-15a-5p, miR-503-5p, miR-16-5p, miR-29a-3p, and miR-29b-3p were significantly upregulated in the liver and pancreas of Cmah-null mice. These target miRNAs are closely associated with dysregulation of insulin/PI3K-AKT signaling, suggesting that the Cmah-null mice could be a useful model for studying diabetes.

  7. Possible associations between antioxidant enzyme polymorphisms and metabolic abnormalities in patients with schizophrenia

    Directory of Open Access Journals (Sweden)

    Saruwatari J

    2013-11-01

    GSTT1 present genotypes than in those with the present genotypes of both genes (odds ratio 3.60, P<0.01. The SOD2 Val16Ala polymorphism was not associated with risk of metabolic abnormalities in either group.Conclusion: The present study suggests that the GSTM1 null genotype, in combination with smoking status or GSTT1 genotype, might be associated with the metabolic abnormalities in patients with schizophrenia.Keywords: schizophrenia, metabolic syndrome, oxidative stress, glutathione S-transferase, superoxide dismutase 2, polymorphism

  8. Analysis of nulling phase functions suitable to image plane coronagraphy

    Science.gov (United States)

    Hénault, François; Carlotti, Alexis; Vérinaud, Christophe

    2016-07-01

    Coronagraphy is a very efficient technique for identifying and characterizing extra-solar planets orbiting in the habitable zone of their parent star, especially in a space environment. An important family of coronagraphs is actually based on phase plates located at an intermediate image plane of the optical system, and spreading the starlight outside the "Lyot" exit pupil plane of the instrument. In this commutation we present a set of candidate phase functions generating a central null at the Lyot plane, and study how it propagates to the image plane of the coronagraph. These functions include linear azimuthal phase ramps (the well-known optical vortex), azimuthally cosine-modulated phase profiles, and circular phase gratings. Nnumerical simulations of the expected null depth, inner working angle, sensitivity to pointing errors, effect of central obscuration located at the pupil or image planes, and effective throughput including image mask and Lyot stop transmissions are presented and discussed. The preliminary conclusion is that azimuthal cosine functions appear as an interesting alternative to the classical optical vortex of integer topological charge.

  9. Null Zig-Zag Wilson Loops in N=4 SYM

    CERN Document Server

    Xie, Zhifeng

    2009-01-01

    In planar ${\\cal N}=4$ supersymmetric Yang-Mills theory we have studied supersymmetric Wilson loops composed of a large number of light-like segments, i.e., null zig-zags. These contours oscillate around smooth underlying spacelike paths. At one-loop in perturbation theory we have compared the finite part of the expectation value of null zig-zags to the finite part of the expectation value of non-scalar-coupled Wilson loops whose contours are the underlying smooth spacelike paths. In arXiv:0710.1060 [hep-th] it was argued that these quantities are equal for the case of a rectangular Wilson loop. Here we present a modest extension of this result to zig-zags of circular shape and zig-zags following non-parallel, disconnected line segments and show analytically that the one-loop finite part is indeed that given by the smooth spacelike Wilson loop without coupling to scalars which the zig-zag contour approximates. We make some comments regarding the generalization to arbitrary shapes.

  10. Null Zig-Zag Wilson Loops in {N}=4 Sym

    Science.gov (United States)

    Xie, Zhifeng

    In planar {N}=4 supersymmetric Yang-Mills theory we have studied one kind of (locally) BPS Wilson loops composed of a large number of light-like segments, i.e. null zig-zags. These contours oscillate around smooth underlying spacelike paths. At one-loop in perturbation theory, we have compared the finite part of the expectation value of null zig-zags to the finite part of the expectation value of non-scalar-coupled Wilson loops whose contours are the underlying smooth spacelike paths. In arXiv:0710.1060 [hep-th] it was argued that these quantities are equal for the case of a rectangular Wilson loop. Here we present a modest extension of this result to zig-zags of circular shape and zig-zags following non-parallel, disconnected line segments and show analytically that the one-loop finite part is indeed that given by the smooth spacelike Wilson loop without coupling to scalars which the zig-zag contour approximates. We make some comments regarding the generalization to arbitrary shapes.

  11. Principal components null space analysis for image and video classification.

    Science.gov (United States)

    Vaswani, Namrata; Chellappa, Rama

    2006-07-01

    We present a new classification algorithm, principal component null space analysis (PCNSA), which is designed for classification problems like object recognition where different classes have unequal and nonwhite noise covariance matrices. PCNSA first obtains a principal components subspace (PCA space) for the entire data. In this PCA space, it finds for each class "i," an Mi-dimensional subspace along which the class' intraclass variance is the smallest. We call this subspace an approximate null space (ANS) since the lowest variance is usually "much smaller" than the highest. A query is classified into class "i" if its distance from the class' mean in the class' ANS is a minimum. We derive upper bounds on classification error probability of PCNSA and use these expressions to compare classification performance of PCNSA with that of subspace linear discriminant analysis (SLDA). We propose a practical modification of PCNSA called progressive-PCNSA that also detects "new" (untrained classes). Finally, we provide an experimental comparison of PCNSA and progressive PCNSA with SLDA and PCA and also with other classification algorithms-linear SVMs, kernel PCA, kernel discriminant analysis, and kernel SLDA, for object recognition and face recognition under large pose/expression variation. We also show applications of PCNSA to two classification problems in video--an action retrieval problem and abnormal activity detection.

  12. Preverbal subjects in null subject languages are not necessarily dislocated

    Directory of Open Access Journals (Sweden)

    João Costa

    2002-12-01

    Full Text Available In recent work on null subject languages it has been claimed that preverbal subjects are always (clitic-left dislocated. In this paper, we argue against this claim, on the grounds of empirical evidence from European Portuguese concerning agreement facts, asymmetries between preverbal subjects and clitic-left dislocated XPs with respect to minimality effects, the existence of languages with a mixed system (null expletive subjects and full referential ones, language acquisition data, the behavior of negative QPs and interpretation facts, and propose a non-uniform analysis of preverbal subjects and clitic-left dislocated XPs that derives their topic interpretation from a predication rule stated configurationally (section 2. Our account of the SVO and VSO orders displayed in European Portuguese relies on a specific formulation of the EPP parameter, on the locality constraint Attract Closest X and on the independently motivated claim that V-movement targets T in European Portuguese (section 3. Under our analysis, the computational system generates equally economical SVO and VSO derivations and discourse considerations, at the appropriate interface, rule out the unfelicitous ones.

  13. Partial rescue of the amelogenin null dental enamel phenotype.

    Science.gov (United States)

    Li, Yong; Suggs, Cynthia; Wright, J Timothy; Yuan, Zhi-an; Aragon, Melissa; Fong, Hanson; Simmons, Darrin; Daly, Bill; Golub, Ellis E; Harrison, Gerald; Kulkarni, Ashok B; Gibson, Carolyn W

    2008-05-30

    The amelogenins are the most abundant secreted proteins in developing dental enamel. Enamel from amelogenin (Amelx) null mice is hypoplastic and disorganized, similar to that observed in X-linked forms of the human enamel defect amelogenesis imperfecta resulting from amelogenin gene mutations. Both transgenic strains that express the most abundant amelogenin (TgM180) have relatively normal enamel, but strains of mice that express a mutated amelogenin (TgP70T), which leads to amelogenesis imperfecta in humans, have heterogeneous enamel structures. When Amelx null (KO) mice were mated with transgenic mice that produce M180 (TgM180), the resultant TgM180KO offspring showed evidence of rescue in enamel thickness, mineral density, and volume in molar teeth. Rescue was not observed in the molars from the TgP70TKO mice. It was concluded that a single amelogenin protein was able to significantly rescue the KO phenotype and that one amino acid change abrogated this function during development.

  14. Holographic Description of Negative Null Energy in Squeezed Vacuum States

    CERN Document Server

    Lee, Da-Shin

    2016-01-01

    Using the AdS/CFT duality, we study the expectation value of stress tensor in squeezed vacuum states of $2+1$-dimensional quantum critical theories with a general dynamical scaling $z$. The holographic dual theory is the theory of gravity in 3+1-dimensional Lifshitz backgrounds. We then adopt a consistent approach to obtain the boundary stress tensor from bulk construction, which satisfies the trace Ward identity associated with Lifshitz scaling symmetry. The scheme for holographic dual of squeezed vacuum states is found to be the gravity theory in the geometry perturbed by gravitational wave. For small squeezing parameters, the expectation value of stress tensor in squeezed vacuum states is obtained for both strongly coupled quantum critical fields and free relativistic fields. We find that, in both cases with $z=1$, the stress tensor satisfies the averaged null energy condition and is consistent with the quantum interest conjecture. In particular, the negative lower bound on null-contracted stress tensor, w...

  15. Pituitary null cell adenoma in a domestic llama (Lama glama).

    Science.gov (United States)

    Chalkley, M D; Kiupel, M; Draper, A C E

    2014-07-01

    Pituitary gland neoplasia has been reported rarely in camelids. A 12-year-old neutered male llama (Lama glama) presented with lethargy, inappetence and neurological signs. On physical examination, the llama was mentally dull and exhibited compulsive pacing and circling to the left. Complete blood count and serum biochemistry revealed haemoconcentration, mild hypophosphataemia, hyperglycaemia, hypercreatininaemia and hyperalbuminaemia. Humane destruction was elected due to rapid clinical deterioration and poor prognosis. Post-mortem examination revealed a pituitary macroadenoma and bilateral internal hydrocephalus. Microscopically, the pituitary tumour was composed of neoplastic chromophobic pituitary cells. Ultrastructural studies revealed similar neoplastic cells to those previously described in human null cell adenomas. Immunohistochemically, the neoplastic cells were strongly immunoreactive for neuroendocrine markers (synaptophysin and chromogranin A), but did not exhibit immunoreactivity for epithelial, mesenchymal, neuronal and all major pituitary hormone markers (adrenocorticotropic hormone, follicle stimulating hormone, growth hormone, luteinizing hormone, melanocyte-stimulating hormone, prolactin and thyroid stimulating hormone), consistent with the diagnosis of a pituitary null cell adenoma. This is the first report of pituitary neoplasia in a llama.

  16. Does horizon entropy satisfy a Quantum Null Energy Conjecture?

    CERN Document Server

    Fu, Zicao

    2016-01-01

    A modern version of the idea that the area of event horizons gives $4G$ times an entropy is the Hubeny-Rangamani Causal Holographic Information (CHI) proposal for holographic field theories. Given a region $R$ of a holographic QFTs, CHI computes $A/4G$ on a certain cut of an event horizon in the gravitational dual. The result is naturally interpreted as a coarse-grained entropy. CHI is known to be finitely greater than the fine-grained Hubeny-Rangamani-Takayanagi (HRT) entropy when $\\partial R$ lies on a Killing horizon of the QFT spacetime, and in this context satisfies other non-trivial properties expected of an entropy. Here we present evidence that it also satisfies the quantum null energy condition (QNEC), which bounds the second derivative of the entropy of a quantum field theory on one side of a non-expanding null surface by the flux of stress-energy across the surface. In particular, we show CHI to satisfy the QNEC in 1+1 holographic CFTs when evaluated in states dual to conical defects in AdS$_3$. Th...

  17. Glutathione S-transferase M1 and T1 genotypes and endometriosis risk: a case-controlled study

    Institute of Scientific and Technical Information of China (English)

    林俊; 张信美; 钱羽力; 叶英辉; 石一复; 徐开红; 徐键云

    2003-01-01

    Objective To investigate the correlation between glutathione S-transferase (GST) M1 and T1 genotypes and endometriosis risk (EM). Methods Polymerase chain reaction (PCR) technique was used to detect the presence or absence of the GSTM1 and GSTT1 genes in genomic DNA isolated from the blood samples of 68 Han Chinese women with endometriosis and 28 without endometriosis. Results The frequencies of GSTM1 and GSTT1 null genotypes in women with endometriosis were 0.721 (49/68) and 0.779 (53/68), respectively, and in women without endometriosis were 0.429 (12/28) and 0.321 (9/28), respectively. There was a significant difference with regard to the frequencies of GSTM1 and GSTT1 null genotypes between the women with and without endometriosis (P0.05). Conclusion GSTM1 and GSTT1 null genotypes may be risk factors for the development of endometriosis.

  18. GSTM1 and APE1 genotypes affect arsenic-induced oxidative stress: a repeated measures study

    National Research Council Canada - National Science Library

    Breton, Carrie V; Kile, Molly L; Catalano, Paul J; Hoffman, Elaine; Quamruzzaman, Quazi; Rahman, Mahmuder; Mahiuddin, Golam; Christiani, David C

    2007-01-01

    .... Generation of oxidative stress may contribute to arsenic carcinogenesis. To investigate the association between arsenic exposure and oxidative stress, urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG...

  19. Genotypes of GSTM1 and GSTT1: Useful determinants for clinical ...

    African Journals Online (AJOL)

    Journal Home > Vol 18, No 1 (2017) > ... Background: Incidence of bladder cancer has increased rapidly worldwide in the past few years. ... Method: Bladder cancer cases (236) and control blood samples (270) were screened using phenol ...

  20. Genotypes of GSTM1 and GSTT1: Useful determinants for clinical ...

    African Journals Online (AJOL)

    Saima Shakil Malik

    2016-04-28

    Apr 28, 2016 ... Commonly reported symptoms by the patients of bladder cancer were hematuria, ... risk factors for gastric, prostate, lung and head and neck can- cer due to their ... or obstructive symptoms (poor stream, hesitancy, terminal.

  1. Error analysis and system optimization of non-null aspheric testing system

    Science.gov (United States)

    Luo, Yongjie; Yang, Yongying; Liu, Dong; Tian, Chao; Zhuo, Yongmo

    2010-10-01

    A non-null aspheric testing system, which employs partial null lens (PNL for short) and reverse iterative optimization reconstruction (ROR for short) technique, is proposed in this paper. Based on system modeling in ray tracing software, the parameter of each optical element is optimized and this makes system modeling more precise. Systematic error of non-null aspheric testing system is analyzed and can be categorized into two types, the error due to surface parameters of PNL in the system modeling and the rest from non-null interferometer by the approach of error storage subtraction. Experimental results show that, after systematic error is removed from testing result of non-null aspheric testing system, the aspheric surface is precisely reconstructed by ROR technique and the consideration of systematic error greatly increase the test accuracy of non-null aspheric testing system.

  2. Survival of glucose phosphate isomerase null somatic cells and germ cells in adult mouse chimaeras.

    Science.gov (United States)

    Keighren, Margaret A; Flockhart, Jean H; West, John D

    2016-05-15

    The mouse Gpi1 gene encodes the glycolytic enzyme glucose phosphate isomerase. Homozygous Gpi1(-/-) null mouse embryos die but a previous study showed that some homozygous Gpi1(-/-) null cells survived when combined with wild-type cells in fetal chimaeras. One adult female Gpi1(-/-)↔Gpi1(c/c) chimaera with functional Gpi1(-/-) null oocytes was also identified in a preliminary study. The aims were to characterise the survival of Gpi1(-/-) null cells in adult Gpi1(-/-)↔Gpi1(c/c) chimaeras and determine if Gpi1(-/-) null germ cells are functional. Analysis of adult Gpi1(-/-)↔Gpi1(c/c) chimaeras with pigment and a reiterated transgenic lineage marker showed that low numbers of homozygous Gpi1(-/-) null cells could survive in many tissues of adult chimaeras, including oocytes. Breeding experiments confirmed that Gpi1(-/-) null oocytes in one female Gpi1(-/-)↔Gpi1(c/c) chimaera were functional and provided preliminary evidence that one male putative Gpi1(-/-)↔Gpi1(c/c) chimaera produced functional spermatozoa from homozygous Gpi1(-/-) null germ cells. Although the male chimaera was almost certainly Gpi1(-/-)↔Gpi1(c/c), this part of the study is considered preliminary because only blood was typed for GPI. Gpi1(-/-) null germ cells should survive in a chimaeric testis if they are supported by wild-type Sertoli cells. It is also feasible that spermatozoa could bypass a block at GPI, but not blocks at some later steps in glycolysis, by using fructose, rather than glucose, as the substrate for glycolysis. Although chimaera analysis proved inefficient for studying the fate of Gpi1(-/-) null germ cells, it successfully identified functional Gpi1(-/-) null oocytes and revealed that some Gpi1(-/-) null cells could survive in many adult tissues.

  3. Research on Null Verb Be in Chinese Based on Minimalist Program Theory

    Institute of Scientific and Technical Information of China (English)

    郭璐

    2013-01-01

    In this paper,based on the null categories and VP-shell light verb inthe Minimalist Program of Chomsky,the author proposed the concept of null verb be in Chinese and then studied the text of Moonlight over the Lotus Pondwritten by Zhuziqing to validate this assumption. The results indicate that null verb be could explain the classification of verbs and adjectives in Chinese as well as some other grammatical phenomena within the framework of Minimalist Program.

  4. Evolution of clustered magnetic nulls in a turbulent-like reconnection region in the magnetotail

    Science.gov (United States)

    Guo, Ruilong; Pu, Zuyin; Fu, Suiyan; Xie, Lun; Dunlop, Malcolm; Bogdanova, Yulia V.; He, Jiansen; Wang, Xin; Yao, Zhonghua

    2016-07-01

    Magnetic null points and flux ropes play important roles in the three-dimensional process of magnetic reconnection. In this study, a cluster of null points are reconstructed in the reconnection region in the magnetotail by applying a fitting-reconstruction method to measurements from the Cluster mission. The number of reconstructed null points varies rapidly, presenting a turbulent-like evolution of the magnetic structure. The electron density and the flux of the accelerated electrons were enhanced in this turbulent-like region. During this unstable reconnection process, a B-As-B null structure was formed, showing flux rope features and resembling a secondary island in the observation.

  5. How to Find Magnetic Nulls and Reconstruct Field Topology with MMS Data?

    Science.gov (United States)

    Fu, H.; Vaivads, A.; Khotyaintsev, Y. V.; Olshevsky, V.; Andre, M.; Cao, J.; Huang, S.; Retino, A.; Lapenta, G.

    2015-12-01

    In this study, we apply a new method—the first-order Taylor expansion (FOTE)—to find magnetic nulls and reconstruct magnetic field topology, in order to use it with the data from the forth-coming MMS mission. We compare this method with the previously used Poincare index (PI), and find that they are generally consistent, except that the PI method can only find a null inside the spacecraft (SC) tetrahedron, while the FOTE method can find a null both inside and outside the tetrahedron and also deduce its drift velocity. In addition, the FOTE method can (1) avoid limitations of the PI method such as data resolution, instrument uncertainty (Bz offset), and SC separation; (2) identify 3D null types (A, B, As, and Bs) and determine whether these types can degenerate into 2D (X and O); (3) reconstruct the magnetic field topology. We quantitively test the accuracy of FOTE in positioning magnetic nulls and reconstructing field topology, by using the data from 3D kinetic simulations. The influences of SC separation (0.05~1 di) and null-SC distance (0~1 di) on the accuracy are both considered. We find that: (1) for an isolated null, the method is accurate when the SC separation is smaller than 1 di, and the null-SC distance is smaller than 0.25~0.5 di; (2) for a null pair, the accuracy is same as in the isolated-null situation, except at the separator line, where the field is nonlinear. We define a parameter in terms of the eigenvalues of the null to quantify the quality of our method—the smaller this parameter the better the results. Comparing to the previously used one, this parameter is more relevant for null identification. Using the new method, we reconstruct the magnetic field topology around a radial-type null and a spiral-type null, and find that the topologies are well consistent with those predicted in theory. We therefore suggest using this method to find magnetic nulls and reconstruct field topology with four-point measurements, particularly from Cluster and

  6. Effects of osmolality on PLP-null myelin structure: Implications re axon damage

    OpenAIRE

    Rosenbluth, Jack; Schiff, Rolf; Lam, Pokman

    2008-01-01

    In order to test the adhesiveness of PLP-null compact myelin lamellae we soaked aldehyde-fixed CNS specimens from PLP-null and control mice overnight in distilled water, in Ringer’s solution or in Ringer’s solution with added 1M sucrose. Subsequent examination of the tissue by EM showed that both PLP-null and control white matter soaked in Ringer remained largely compact. After the distilled water soak, control myelin was virtually unchanged, but PLP-null myelin showed some decompaction, i.e....

  7. A TRUST REGION ALGORITHM WITH NULL SPACE TECHNIQUE FOR EQUALITY CONSTRAINED OPTIMIZATION

    Institute of Scientific and Technical Information of China (English)

    TONG Xiaojiao; LI Donghui

    2004-01-01

    This paper presents a trust region algorithm with null space technique fornonlinear equality constrained optimizationConsidering in the null space methods that,the convergent rate of range space step is faster than the null space step for the most cases,the proposed algorithm computes null steps more often than range space stepMoreover,the new algorithm is based on the reduced Hessian SQP methodGlobal convergence ofthe proposed algorithm is provedThe effectiveness of the method is demonstrated bysome numerical examples.

  8. Null quadrature domains and a free boundary problem for the Laplacian

    CERN Document Server

    Karp, Lavi

    2010-01-01

    Null quadrature domains are unbounded domains in $\\R^n$ ($n \\geq 2$) with external gravitational force zero in some generalized sense. In this paper we prove a quadratic growth estimate of the Schwarz potential of a null quadrature domain and conclude by a theorem of Caffarelli, Karp and Shahgolian that any null quadrature domain is the complement of a convex set with analytic boundary. Using this result we prove that a null quadrature domain with a non-zero upper Lebesgue density at infinity is half-space.

  9. Lung mechanics in the TIMP3 null mouse and its response to mechanical ventilation.

    Science.gov (United States)

    Martin, Erica L; Truscott, Emily A; Bailey, Timothy C; Leco, Kevin J; McCaig, Lynda A; Lewis, James F; Veldhuizen, Ruud A W

    2007-03-01

    Tissue inhibitor of metalloproteinase-3 (TIMP3) null mice develop emphysema-like airspace enlargement due to an enzymatic imbalance. This study investigates how these abnormalities alter lung mechanics and the response to 2 different mechanical ventilation strategies. Phenotypically, TIMP3 null mice had increased compliance, and decreased resistance, tissue damping, and tissue elastance over wild-type controls. Decreased compliance and increased resistance were observed following the injurious ventilation strategy; however, the TIMP3 null response to both ventilation strategies was similar to wild-type mice. In conclusion, TIMP3 null mice have significant alterations in lung mechanics; however, this does not affect their response to ventilation.

  10. Reduced infarct size in neuroglobin-null mice after experimental stroke in vivo

    DEFF Research Database (Denmark)

    Raida, Zindy; Hundahl, Christian Ansgar; Kelsen, Jesper;

    2012-01-01

    , then permanent cerebral ischemia would lead to larger infarct volumes in neuroglobin-null mice than in wild-type mice. METHODS: Using neuroglobin-null mice, we estimated the infarct volume 24 hours after permanent middle cerebral artery occlusion using Cavalieri's Principle, and compared the infarct volume...... in neuroglobin-null and wild-type mice. Neuroglobin antibody staining was used to examine neuroglobin expression in the infarct area of wild-type mice. RESULTS: Infarct volumes 24 hours after permanent middle cerebral artery occlusion were significantly smaller in neuroglobin-null mice than in wild-types (p 

  11. Alignment of optical system components using an ADM beam through a null assembly

    Science.gov (United States)

    Hayden, Joseph E. (Inventor); Olczak, Eugene G. (Inventor)

    2010-01-01

    A system for testing an optical surface includes a rangefinder configured to emit a light beam and a null assembly located between the rangefinder and the optical surface. The null assembly is configured to receive and to reflect the emitted light beam toward the optical surface. The light beam reflected from the null assembly is further reflected back from the optical surface toward the null assembly as a return light beam. The rangefinder is configured to measure a distance to the optical surface using the return light beam.

  12. Jet phenomena above null points of the coronal magnetic field

    Science.gov (United States)

    Filippov, B.; Koutchmy, S.; Golub, L.

    2009-12-01

    Short-lived plasma jets of various scales, from giant X-ray jets more than 300 Mm in extent to numerous small jets with sizes typical of macrospicules, are the phenomena observed in the solar corona in extreme ultraviolet and X-ray emission. Small jets are particularly prominent in polar coronal holes. They are close neighbors of tiny bright loops and coincide in time with their sudden brightening and increase in size. The geometric shape of the jets and their location suggest that they arise near singular null points of the coronal magnetic field. These points appear in coronal holes due to the emergence of small bipolar or unipolar magnetic structures within large-scale unipolar cells. Polar jets show a distinct vertical plasma motion in a coronal hole that introduces significant momentum and mass into the solar wind flow. Investigating the dynamics of polar jets can elucidate certain details in the problem of fast solar wind acceleration.

  13. Null polarimetry near shot noise limit at 1 Hz.

    Science.gov (United States)

    He, Dechao; Xie, Boya; Feng, Sheng

    2016-04-01

    We describe the principle and report on the realization of a null polarimeter with two demonstrated features: (1) the sensitivity of the system is near shot noise limit and (2) quasi-stationary signals at 1 Hz can be measured without signal modulation. The achieved single-pass sensitivity is 7 × 10(-9) rad/Hz with a pair of Glan-Taylor polarizers, which should be of great interest for experiments such as observation of vacuum magnetic birefringence and search for new particles. The system is brought near its shot noise limit by appropriate polarization control and coherent heterodyne detection of light, resulting in a sensitivity improvement by two orders of magnitude in comparison with the case of no control on light polarization.

  14. Null Geodesics in a Magnetically Charged Stringy Black Hole Spacetime

    CERN Document Server

    Kuniyal, Ravi Shankar; Nandan, Hemwati; Purohit, K D

    2015-01-01

    We study the geodesic motion of massless test particles in the background of a magnetic charged black hole spacetime in four dimensions in dilaton-Maxwell gravity. The behaviour of effective potential in view of the different values of black hole parameters is analysed in the equatorial plane. The possible orbits for null geodesics are also discussed in detail in view of the different values of the impact parameter. We have also calculated the frequency shift of photons in this spacetime. The results obtained are then compared with those for the electrically charged stringy black hole spacetime and the Schwarzschild black hole spacetime. It is observed that there exists no stable circular orbit outside the event horizon for massless test particles.

  15. Power spectrum nulls due to non-standard inflationary evolution

    CERN Document Server

    Goswami, Gaurav

    2010-01-01

    The simplest models of inflation based on slow roll produce nearly scale invariant primordial power spectra (PPS). But there are also numerous models that predict radically broken scale invariant PPS. In particular, markedly cuspy dips in the PPS correspond to nulls where the perturbation amplitude, hence PPS, goes through a zero at a specific wavenumber. Near this wavenumber, the true quantum nature of the generation mechanism of the primordial fluctuations may be revealed. Naively these features may appear to arise from fine tuned initial conditions. However, we show that this behavior arises under fairly generic set of conditions involving super-Hubble scale evolution of perturbation modes during inflation. We illustrate this with the well-studied examples of punctuated inflation and the Starobinsky-break model.

  16. From Satisfying to Violating the Null Energy Condition

    CERN Document Server

    Elder, Benjamin; Khoury, Justin

    2013-01-01

    We construct a theory which admits a time-dependent solution smoothly interpolating between a null energy condition (NEC)-satisfying phase at early times and a NEC-violating phase at late times. We first review earlier attempts to violate the NEC and an argument of Rubakov, presented in 1305.2614, which forbids the existence of such interpolating solutions in a single-field dilation-invariant theory. We then construct a theory which, in addition to possessing a Poincar\\'e-invariant vacuum, does admit such a solution. For a wide range of parameters, perturbations around this solution are at all times stable, comfortably subluminal and weakly-coupled. The theory requires us to explicitly break dilation-invariance, so it is unlikely that the theory is fully stable under quantum corrections, but we argue that the existence of a healthy interpolating solution is quantum-mechanically robust.

  17. Null-stream pointing with pulsar timing arrays

    CERN Document Server

    Hazboun, Jeffrey S

    2016-01-01

    Locating sources on the sky is one of the largest challenges in gravitational wave astronomy, owing to the omni-directional nature of gravitational wave detection techniques, and the often intrinsically weak signals being observed. Ground-based detectors can address the pointing problem by observing with a network of detectors, effectively triangulating signal locations by observing the arrival times across the network. Space-based detectors will observe long-lived sources that persist while the detector moves relative to their location on the sky, using Doppler shifts of the signal to locate the sky position. While these methods improve the pointing capability of a detector or network, the angular resolution is still coarse compared to the standards one expects from electromagnetic astronomy. Another technique that can be used for sky localization is null-stream pointing. In the case where multiple independent data streams exist, a single astrophysical source of gravitational waves will appear in each of the...

  18. Solar Particle Acceleration at Reconnecting 3D Null Points

    CERN Document Server

    Stanier, Adam J; Dalla, Silvia

    2012-01-01

    Context: The strong electric fields associated with magnetic reconnection in solar flares are a plausible mechanism to accelerate populations of high energy, non-thermal particles. One such reconnection scenario occurs at a 3D magnetic null point, where global plasma flows give rise to strong currents in the spine axis or fan plane. Aims: To understand the mechanism of charged particle energy gain in both the external drift region and the diffusion region associated with 3D magnetic reconnection. In doing so we evaluate the efficiency of resistive spine and fan models for particle acceleration, and find possible observables for each. Method: We use a full orbit test particle approach to study proton trajectories within electromagnetic fields that are exact solutions to the steady and incompressible magnetohydrodynamic equations. We study single particle trajectories and find energy spectra from many particle simulations. The scaling properties of the accelerated particles with respect to field and plasma para...

  19. A new interferometer architecture combining nulling with phase closure measurements

    CERN Document Server

    Lacour, S; Monnier, J D; Kotani, T; Gauchet, L; Labeye, P

    2013-01-01

    Imaging the direct light signal from a faint exoplanet against the overwhelming glare of its host star presents one of the fundamental challenges to modern astronomical instrumentation. Achieving sufficient signal-to-noise for detection by direct imaging is limited by three basic physical processes: aberration of the wavefronts (both instrumental and atmospheric), photon noise, and detector noise. In this paper, we advance a novel optical setup which synthesizes the advantages of two different techniques: nulling interferometry to mitigate photon noise, and closure phase to combat optical aberrations. Our design, which employs technology from integrated optics and photonics, is intended to combine the advantageous aspects of both a coronagraph and a non-redundant interferometer. We show that such an instrument would allow readout noise limited detection of exoplanets, even in the presence of residual co-phasing errors. As a result, this concept would be ideal for space interferometry and for ground based obse...

  20. Fresnel rhombs as achromatic phase shifters for infrared nulling interferometry

    Science.gov (United States)

    Mawet, D.; Hanot, C.; Lenaers, C.; Riaud, P.; Defrère, D.; Vandormael, D.; Loicq, J.; Fleury, K.; Plesseria, J. Y.; Surdej, J.; Habraken, S.

    2007-09-01

    We propose a new family of achromatic phase shifters for infrared nulling interferometry. These key optical components can be seen as optimized Fresnel rhombs, using the total internal reflection phenomenon, modulated or not. The total internal reflection indeed comes with a phase shift between the polarization components of the incident light. We propose a solution to implement this vectorial phase shift between interferometer arms to provide the destructive interference process needed to disentangle highly contrasted objects from one another. We also show that, modulating the index transition at the total internal reflection interface allows compensating for the intrinsic material dispersion in order to make the subsequent phase shift achromatic over especially broad bands. The modulation can be induced by a thin film of a well-chosen material or a subwavelength grating whose structural parameters are thoroughly optimized. We present results from theoretical simulations! together with preliminary fabrication outcomes and measurements for a prototype in Zinc Selenide.

  1. Linearized gravitational waves near space-like and null infinity

    CERN Document Server

    Beyer, Florian; Frauendiener, Jörg; Whale, Ben

    2013-01-01

    Linear perturbations on Minkowski space are used to probe numerically the remote region of an asymptotically flat space-time close to spatial infinity. The study is undertaken within the framework of Friedrich's conformal field equations and the corresponding conformal representation of spatial infinity as a cylinder. The system under consideration is the (linear) zero-rest-mass equation for a spin-2 field. The spherical symmetry of the underlying background is used to decompose the field into separate non-interacting multipoles. It is demonstrated that it is possible to reach null-infinity from initial data on an asymptotically Euclidean hyper-surface and that the physically important radiation field can be extracted accurately on $\\scri^+$.

  2. On the Null Trajectories in Conformal Weyl Gravity

    CERN Document Server

    Villanueva, J R

    2013-01-01

    In this work we find analytical solutions to the null geodesics around a black hole in the conformal Weyl gravity. Exact expressions for the horizons are found, and they depend on the cosmological constant and the coupling constants of the conformal Weyl gravity. Then, we study the radial motion from the point of view of the proper and coordinate frames, and compare it with that found in spacetimes of general relativity. The angular motion is also examined qualitatively by means of an effective potential; quantitatively, the equation of motion is solved in terms of $\\wp$-Weierstrass elliptic function. Thus, we find the deflection angle for photons without using any approximation, which is a novel result for this kind of gravity.

  3. An Operator Product Expansion for Polygonal null Wilson Loops

    CERN Document Server

    Alday, Luis F; Maldacena, Juan; Sever, Amit; Vieira, Pedro

    2010-01-01

    We consider polygonal Wilson loops with null edges in conformal gauge theories. We derive an OPE-like expansion when several successive lines of the polygon are becoming aligned. The limit corresponds to a collinear, or multicollinear, limit and we explain the systematics of all the subleading corrections, going beyond the leading terms that were previously considered. These subleading corrections are governed by excitations of high spin operators, or excitations of a flux tube that goes between two Wilson lines. The discussion is valid for any conformal gauge theory, for any coupling and in any dimension. For N=4 super Yang Mills we check this expansion at strong coupling and at two loops at weak coupling . We also make predictions for the remainder function at higher loops. In the process, we also derived a new version for the TBA integral equations that determine the strong coupling answer and present the area as the associated Yang-Yang functional.

  4. Surprising structures hiding in Penrose’s future null infinity

    Science.gov (United States)

    Newman, Ezra T.

    2017-07-01

    Since the late1950s, almost all discussions of asymptotically flat (Einstein-Maxwell) space-times have taken place in the context of Penrose’s null infinity, I+. In addition, almost all calculations have used the Bondi coordinate and tetrad systems. Beginning with a known asymptotically flat solution to the Einstein-Maxwell equations, we show first, that there are other natural coordinate systems, near I+, (analogous to light-cones in flat-space) that are based on (asymptotically) shear-free null geodesic congruences (analogous to the flat-space case). Using these new coordinates and their associated tetrad, we define the complex dipole moment, (the mass dipole plus i times angular momentum), from the l  =  1 harmonic coefficient of a component of the asymptotic Weyl tensor. Second, from this definition, from the Bianchi identities and from the Bondi-Sachs mass and linear momentum, we show that there exists a large number of results—identifications and dynamics—identical to those of classical mechanics and electrodynamics. They include, among many others, {P}=M{v}+..., {L}= {r} × {P} , spin, Newton’s second law with the rocket force term (\\dotM v) and radiation reaction, angular momentum conservation and others. All these relations take place in the rather mysterious H-space rather than in space-time. This leads to the enigma: ‘why do these well known relations of classical mechanics take place in H-space?’ and ‘What is the physical meaning of H-space?’

  5. Cadmium modulates adipocyte functions in metallothionein-null mice

    Energy Technology Data Exchange (ETDEWEB)

    Kawakami, Takashige; Nishiyama, Kaori; Kadota, Yoshito; Sato, Masao; Inoue, Masahisa; Suzuki, Shinya, E-mail: suzukis@ph.bunri-u.ac.jp

    2013-11-01

    Our previous study has demonstrated that exposure to cadmium (Cd), a toxic heavy metal, causes a reduction of adipocyte size and the modulation of adipokine expression. To further investigate the significance of the Cd action, we studied the effect of Cd on the white adipose tissue (WAT) of metallothionein null (MT{sup −/−}) mice, which cannot form atoxic Cd–MT complexes and are used for evaluating Cd as free ions, and wild type (MT{sup +/+}) mice. Cd administration more significantly reduced the adipocyte size of MT{sup −/−} mice than that of MT{sup +/+} mice. Cd exposure also induced macrophage recruitment to WAT with an increase in the expression level of Ccl2 (MCP-1) in the MT{sup −/−} mice. The in vitro exposure of Cd to adipocytes induce triglyceride release into culture medium, decrease in the expression levels of genes involved in fatty acid synthesis and lipid hydrolysis at 24 h, and at 48 h increase in phosphorylation of the lipid-droplet-associated protein perilipin, which facilitates the degradation of stored lipids in adipocytes. Therefore, the reduction in adipocyte size by Cd may arise from an imbalance between lipid synthesis and lipolysis. In addition, the expression levels of leptin, adiponectin and resistin decreased in adipocytes. Taken together, exposure to Cd may induce unusually small adipocytes and modulate the expression of adipokines differently from the case of physiologically small adipocytes, and may accelerate the risk of developing insulin resistance and type 2 diabetes. - Highlights: • Cd causes a marked reduction in adipocyte size in MT-null mice. • Cd enhances macrophage migration into adipose tissue and disrupt adipokine secretion. • MT gene alleviates Cd-induced adipocyte dysfunctions. • Cd enhances the degradation of stored lipids in adipocytes, mediated by perilipin. • Cd induces unusually small adipocytes and the abnormal expression of adipokines.

  6. Does horizon entropy satisfy a quantum null energy conjecture?

    Science.gov (United States)

    Fu, Zicao; Marolf, Donald

    2016-12-01

    A modern version of the idea that the area of event horizons gives 4G times an entropy is the Hubeny-Rangamani causal holographic information (CHI) proposal for holographic field theories. Given a region R of a holographic QFTs, CHI computes A/4G on a certain cut of an event horizon in the gravitational dual. The result is naturally interpreted as a coarse-grained entropy for the QFT. CHI is known to be finitely greater than the fine-grained Hubeny-Rangamani-Takayanagi (HRT) entropy when \\partial R lies on a Killing horizon of the QFT spacetime, and in this context satisfies other non-trivial properties expected of an entropy. Here we present evidence that it also satisfies the quantum null energy condition (QNEC), which bounds the second derivative of the entropy of a quantum field theory on one side of a non-expanding null surface by the flux of stress-energy across the surface. In particular, we show CHI to satisfy the QNEC in 1  +  1 holographic CFTs when evaluated in states dual to conical defects in AdS3. This surprising result further supports the idea that CHI defines a useful notion of coarse-grained holographic entropy, and suggests unprecedented bounds on the rate at which bulk horizon generators emerge from a caustic. To supplement our motivation, we include an appendix deriving a corresponding coarse-grained generalized second law for 1  +  1 holographic CFTs perturbatively coupled to dilaton gravity.

  7. Dinucleotide controlled null models for comparative RNA gene prediction

    Directory of Open Access Journals (Sweden)

    Gesell Tanja

    2008-05-01

    Full Text Available Abstract Background Comparative prediction of RNA structures can be used to identify functional noncoding RNAs in genomic screens. It was shown recently by Babak et al. [BMC Bioinformatics. 8:33] that RNA gene prediction programs can be biased by the genomic dinucleotide content, in particular those programs using a thermodynamic folding model including stacking energies. As a consequence, there is need for dinucleotide-preserving control strategies to assess the significance of such predictions. While there have been randomization algorithms for single sequences for many years, the problem has remained challenging for multiple alignments and there is currently no algorithm available. Results We present a program called SISSIz that simulates multiple alignments of a given average dinucleotide content. Meeting additional requirements of an accurate null model, the randomized alignments are on average of the same sequence diversity and preserve local conservation and gap patterns. We make use of a phylogenetic substitution model that includes overlapping dependencies and site-specific rates. Using fast heuristics and a distance based approach, a tree is estimated under this model which is used to guide the simulations. The new algorithm is tested on vertebrate genomic alignments and the effect on RNA structure predictions is studied. In addition, we directly combined the new null model with the RNAalifold consensus folding algorithm giving a new variant of a thermodynamic structure based RNA gene finding program that is not biased by the dinucleotide content. Conclusion SISSIz implements an efficient algorithm to randomize multiple alignments preserving dinucleotide content. It can be used to get more accurate estimates of false positive rates of existing programs, to produce negative controls for the training of machine learning based programs, or as standalone RNA gene finding program. Other applications in comparative genomics that require

  8. Is PMI the Hypothesis or the Null Hypothesis?

    Science.gov (United States)

    Tarone, Aaron M; Sanford, Michelle R

    2017-09-01

    Over the past several decades, there have been several strident exchanges regarding whether forensic entomologists estimate the postmortem interval (PMI), minimum PMI, or something else. During that time, there has been a proliferation of terminology reflecting this concern regarding "what we do." This has been a frustrating conversation for some in the community because much of this debate appears to be centered on what assumptions are acknowledged directly and which are embedded within a list of assumptions (or ignored altogether) in the literature and in case reports. An additional component of the conversation centers on a concern that moving away from the use of certain terminology like PMI acknowledges limitations and problems that would make the application of entomology appear less useful in court-a problem for lawyers, but one that should not be problematic for scientists in the forensic entomology community, as uncertainty is part of science that should and can be presented effectively in the courtroom (e.g., population genetic concepts in forensics). Unfortunately, a consequence of the way this conversation is conducted is that even as all involved in the debate acknowledge the concerns of their colleagues, parties continue to talk past one another advocating their preferred terminology. Progress will not be made until the community recognizes that all of the terms under consideration take the form of null hypothesis statements and that thinking about "what we do" as a null hypothesis has useful legal and scientific ramifications that transcend arguments over the usage of preferred terminology. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  9. iNOS null MRL+/+ mice show attenuation of trichloroethene-mediated autoimmunity: contribution of reactive nitrogen species and lipid-derived reactive aldehydes.

    Science.gov (United States)

    Wang, Gangduo; Wakamiya, Maki; Wang, Jianling; Ansari, G A S; Firoze Khan, M

    2015-12-01

    Earlier studies from our laboratory in MRL+/+ mice suggest that free radicals, especially overproduction of reactive nitrogen species (RNS) and lipid-derived reactive aldehydes (LDRAs), are associated with trichloroethene (TCE)-mediated autoimmune response. The current study was undertaken to further assess the contribution of RNS and LDRAs in TCE-mediated autoimmunity by using iNOS-null MRL+/+ mice. iNOS-null MRL+/+ mice were obtained by backcrossing iNOS-null mice (B6.129P2-Nos2(tm1Lau)/J) to MRL +/+ mice. Female MRL+/+ and iNOS-null MRL+/+ mice were given TCE (10 mmol/kg, i.p., every 4(th) day) for 6 weeks; their respective controls received corn oil only. TCE exposure led to significantly increased iNOS mRNA in livers, iNOS protein in livers and sera, increased nitrotyrosine (NT) formation in both livers and sera, induction of MDA-/HNE-protein adducts in livers and their respective antibodies in sera along with significant increases in serum antinuclear antibodies (ANA) and anti-dsDNA in MRL+/+ mice. Even though in iNOS-null MRL+/+ mice, the iNOS and NT levels were negligible in both TCE-treated and untreated groups, TCE treatment still led to significant increases in MDA-/HNE-protein adducts and their respective antibodies along with increases in serum ANA and anti-dsDNA compared to controls. Most remarkably, the increases in serum ANA and anti-dsDNA induced by TCE in the iNOS-null MRL+/+ mice were significantly less pronounced compared to that in MRL+/+ mice. Our results provide further evidence that both RNS and LDRAs contribute to TCE-induced autoimmunity in MRL+/+ mice, and iNOS deficiency attenuates this autoimmune response.

  10. Reconsidering the Null Hypothesis: Is Maternal Rank Associated with Birth Sex Ratios in Primate Groups?

    National Research Council Canada - National Science Library

    Gillian R. Brown; Joan B. Silk

    2002-01-01

    Trivers and Willard hypothesized that vertebrates adaptively vary the sex ratio of their offspring in response to the mother's physical condition [Trivers, R. L. & Willard, D. (1973) Science 179, 90-92...

  11. Over-fitting Time Series Models of Air Pollution Health Effects: Smoothing Tends to Bias Non-Null Associations Towards the Null.

    Science.gov (United States)

    Background: Simulation studies have previously demonstrated that time-series analyses using smoothing splines correctly model null health-air pollution associations. Methods: We repeatedly simulated season, meteorology and air quality for the metropolitan area of Atlanta from cyc...

  12. How to find magnetic null and construct field topology with MMS data?

    Science.gov (United States)

    Fu, Huishan; Vaivads, Andris; Khotyaintsev, Yuri; Olshevsky, Vyacheslav; Andre, Mats; Cao, Jinbin; Huang, Shiyong; Retino, Alessandro; Eastwood, Jonathan

    2015-04-01

    In this study, we apply a new method'Taylor expansion'to find magnetic null and construct magnetic field topology, in order to use it with the data from the forth-coming MMS mission. We compare this method with the previously used Poincare index (PI), and find that they are generally consistent, except that the PI method can only find a null inside the spacecraft (SC) tetrahedron, while the Taylor expansion can find a null both inside and outside the tetrahedron and also deduce its drift velocity. Taylor expansion can also: (1) avoid the limitations of PI method such as data resolution, instrument uncertainty (Bz offset), and SC separation; (2) identify 3D null types (A, B, As, and Bs) and determine whether these types can degenerate into 2D (X and O); (3) construct the magnetic field topology. We quantitively test the accurateness of Taylor expansion in positioning magnetic null and constructing field topology, by using the data from 3D kinetic simulations. The influences of SC separation (from 0.05 to 1 di) and null-SC distance (from 0 to 1 di) on the accurateness are both considered. We find that: (1) for single null, the method is accurate when the SC separation is smaller than 1 di, and the null-SC distance is smaller than 0.5 di (weakly chaotic reconnection) or 0.25 di (strongly chaotic reconnection); (2) for null pair, the accurateness is same as the single-null situation, except at the null-null line, where the field is nonlinear. We invent a parameter ξ ≡|(λ1 + λ2 + λ3)|/ |λ|max to quantify the quality of the method'the smaller this parameter the better the results. Comparing to the previously used one (η ≡|downtriangle -B|/ |downtriangle × B |), this parameter is more relevant. Using the new method, we construct the magnetic field topology around a radial-type null and a spiral-type null, and find that the topologies are well consistent with those predicted in theory. This means that our method is reliable. We therefore suggest using this

  13. Renal NHE expression and activity in neonatal NHE3- and NHE8-null mice.

    Science.gov (United States)

    Pirojsakul, Kwanchai; Gattineni, Jyothsna; Dwarakanath, Vangipuram; Baum, Michel

    2015-01-01

    Na(+)/H(+) exchanger (NHE)3 is the predominant NHE on the brush-border membrane of the proximal tubule in adult animals. NHE8 has been localized to the brush-border membrane of proximal tubules and is more highly expressed in neonates than in adult animals. However, the relative role of NHE8 in neonatal renal acidification is unclear. The present study examined if there was a compensatory increase in NHE3 in NHE8-null neonatal mice and whether there was a compensatory increase in NHE8 in NHE3-null neonatal mice. In addition, we examined whether wild-type, NHE3-null, and NHE8-null mice had an increase in NHE activity in response to metabolic acidosis. We found that at baseline, there was comparable renal NHE3 mRNA, total protein, and brush-border membrane protein abundance as in neonatal control and NHE8-null mice. There was comparable renal NHE8 mRNA, total protein, and brush-border membrane protein abundance in NHE3-null neonatal and control mice. Both NHE3- and NHE8-null mice had a comparable but lower rate of NHE activity than control mice. We next imposed metabolic acidosis in wild-type, NHE3-null, and NHE8-null mice. Acidemic NHE8-null mice had an increase in brush-border membrane vesicle NHE3 protein abundance and NHE activity compared with vehicle-treated mice. Likewise, NHE3-null mice had an increase in NHE8 brush-border membrane protein abundance and NHE activity in response to metabolic acidosis. In conclusion, both NHE3 and NHE8 likely play a role in neonatal acidification.

  14. null Faults, null Images

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Through the study of faults and their effects, much can be learned about the size and recurrence intervals of earthquakes. Faults also teach us about crustal...

  15. Null controllability of the viscous Camassa–Holm equation with moving control

    Indian Academy of Sciences (India)

    Peng Gao

    2016-02-01

    In this paper, we study the null controllability of the viscous Camassa–Holm equation on the one-dimensional torus. By using a moving distributed control, we obtain that the system is null controllable for a given data with certain regularity.

  16. The role of amplitude, phase, polarization and their interconnection in nulling interferometry

    NARCIS (Netherlands)

    Spronck, J.F.P.

    2008-01-01

    Nulling interferometry is a promising technique to directly detect Earth-like exoplanets. Unfortunately, it is extremely challenging to build a nulling interferometer and to meet the requirements needed for Earth-like planet detection. In this, thesis, we analyze the role of amplitude, phase and pol

  17. Chromatism compensation in wide-band nulling interferometry for exoplanet detection

    NARCIS (Netherlands)

    Spronck, J.; Pereira, S.F.; Braat, J.J.M.

    2006-01-01

    We introduce the concept of chromatism compensation in nulling interferometry that enables a high rejection ratio in a wide spectral band. Therefore the achromaticity condition considered in most nulling interferometers can be relaxed. We show that this chromatism compensation cannot be applied to a

  18. The effect of the longitudinal polarization component in multi-axial nulling interferometry for exoplanet detection

    NARCIS (Netherlands)

    Spronck, J.F.P.; Pereira, S.F.

    2009-01-01

    We show a fundamental limitation of multi-axial beam combiners in nulling interferometry. The longitudinal electric field induced by the focusing optics can drastically limit the performance of such a nulling interferometer. We further analyze the filtering capabilities of a single-mode optical fibe

  19. Toward quantifying uncertainty in travel time tomography using the null-space shuttle

    NARCIS (Netherlands)

    Wit, R.W.L. de; Trampert, J.; van der Hilst, R.D.

    2012-01-01

    The solution of large linear tomographic inverse problems is fundamentally non-unique. We suggest to explore the non-uniqueness explicitly by examining the null-space of the forward operator. We show that with the null-space shuttle it is possible to assess robustness in tomographic models, and we i

  20. Qualification of a Null Lens Using Image-Based Phase Retrieval

    Science.gov (United States)

    Bolcar, Matthew R.; Aronstein, David L.; Hill, Peter C.; Smith, J. Scott; Zielinski, Thomas P.

    2012-01-01

    In measuring the figure error of an aspheric optic using a null lens, the wavefront contribution from the null lens must be independently and accurately characterized in order to isolate the optical performance of the aspheric optic alone. Various techniques can be used to characterize such a null lens, including interferometry, profilometry and image-based methods. Only image-based methods, such as phase retrieval, can measure the null-lens wavefront in situ - in single-pass, and at the same conjugates and in the same alignment state in which the null lens will ultimately be used - with no additional optical components. Due to the intended purpose of a Dull lens (e.g., to null a large aspheric wavefront with a near-equal-but-opposite spherical wavefront), characterizing a null-lens wavefront presents several challenges to image-based phase retrieval: Large wavefront slopes and high-dynamic-range data decrease the capture range of phase-retrieval algorithms, increase the requirements on the fidelity of the forward model of the optical system, and make it difficult to extract diagnostic information (e.g., the system F/#) from the image data. In this paper, we present a study of these effects on phase-retrieval algorithms in the context of a null lens used in component development for the Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission. Approaches for mitigation are also discussed.

  1. Hypersensitivities for acetaldehyde and other agents among cancer cells null for clinically relevant Fanconi anemia genes.

    Science.gov (United States)

    Ghosh, Soma; Sur, Surojit; Yerram, Sashidhar R; Rago, Carlo; Bhunia, Anil K; Hossain, M Zulfiquer; Paun, Bogdan C; Ren, Yunzhao R; Iacobuzio-Donahue, Christine A; Azad, Nilofer A; Kern, Scott E

    2014-01-01

    Large-magnitude numerical distinctions (>10-fold) among drug responses of genetically contrasting cancers were crucial for guiding the development of some targeted therapies. Similar strategies brought epidemiological clues and prevention goals for genetic diseases. Such numerical guides, however, were incomplete or low magnitude for Fanconi anemia pathway (FANC) gene mutations relevant to cancer in FANC-mutation carriers (heterozygotes). We generated a four-gene FANC-null cancer panel, including the engineering of new PALB2/FANCN-null cancer cells by homologous recombination. A characteristic matching of FANCC-null, FANCG-null, BRCA2/FANCD1-null, and PALB2/FANCN-null phenotypes was confirmed by uniform tumor regression on single-dose cross-linker therapy in mice and by shared chemical hypersensitivities to various inter-strand cross-linking agents and γ-radiation in vitro. Some compounds, however, had contrasting magnitudes of sensitivity; a strikingly high (19- to 22-fold) hypersensitivity was seen among PALB2-null and BRCA2-null cells for the ethanol metabolite, acetaldehyde, associated with widespread chromosomal breakage at a concentration not producing breaks in parental cells. Because FANC-defective cancer cells can share or differ in their chemical sensitivities, patterns of selective hypersensitivity hold implications for the evolutionary understanding of this pathway. Clinical decisions for cancer-relevant prevention and management of FANC-mutation carriers could be modified by expanded studies of high-magnitude sensitivities.

  2. Learning How to License Null Noun-Class Prefixes in Sesotho

    Science.gov (United States)

    Demuth, Katherine; Machobane, Malillo; Moloi, Francina

    2009-01-01

    Noun-class prefixes are obligatory in most Bantu languages. However, the Sotho languages (Sesotho, Setswana, Sepedi) permit a subset of prefixes to be realized as null at the intersection of "unmarked" phonological, syntactic, and discourse conditions. This raises the question of how and when the licensing of null prefixes is learned. Using…

  3. The Thromboxane Receptor Antagonist S18886 influence the stability of atherosclerosis in ApoE Null Mice

    Institute of Scientific and Technical Information of China (English)

    Cong Hongliang; Xiang Nina; Chen Yingchong; Julie H

    2005-01-01

    Objectives To investigate whether thromboxane receptor antagonist S18886 inhibits infiltrating macrophages to vessel wall and influence the morphology of atherosclerotic plaque;The effective of S18886 compared to clopidegrol on the development of atherosclerosis, accumulation of lipidfilled macropha-ges in apoE null mice. Methods All mice were done cuffed common carotid artery and fed a Western-type atherogenic diet for 6 weeks from the day of surgery, at same time the therapy group mice were gavaged S18886 5 mg/Kg/day and clopidegrol respectively, the same volume water were gavaged as the placebo group. Results profound inhibition of lesion area growth after cuff of the right common carotid artery in mice with 5 mg/kg of S18886, markdely reduce intima to media ratio and intima to total wall area compare with clopidegrol or blank group; Macrophage infiltration into sites of arterial plaque was also markedly attenuated by ICAM-1 deficiency in the S18886 group, whereas inside the arterial wall plaque of placebo apoE null mice α-smooth muscle actin markedly attenuated. Treatment with 25 mg/kg/day clopidegrol reduced the level of ICAM-1 staining, both S18886 and clopidegrol didn't influence the α-smooth muscle actin inside plaque. Conclusions It was considered that the novel anti-thrombotic drug significant reduce macrophage infiltration in the sites of arterial plaque by ICAM- 1 deficiency, S 18886 not only reduce the size, but also stabilized the plaque.

  4. Fibrosis and inflammation are greater in muscles of beta-sarcoglycan-null mouse than mdx mouse.

    Science.gov (United States)

    Gibertini, Sara; Zanotti, Simona; Savadori, Paolo; Curcio, Maurizio; Saredi, Simona; Salerno, Franco; Andreetta, Francesca; Bernasconi, Pia; Mantegazza, Renato; Mora, Marina

    2014-05-01

    The Sgcb-null mouse, with knocked-down β-sarcoglycan, develops severe muscular dystrophy as in type 2E human limb girdle muscular dystrophy. The mdx mouse, lacking dystrophin, is the most used model for Duchenne muscular dystrophy (DMD). Unlike DMD, the mdx mouse has mild clinical features and shows little fibrosis in limb muscles. To characterize ECM protein deposition and the progression of muscle fibrosis, we evaluated protein and transcript levels of collagens I, III and VI, decorin, and TGF-β1, in quadriceps and diaphragm, at 2, 4, 8, 12, 26, and 52 weeks in Sgcb-null mice, and protein levels at 12, 26, and 52 weeks in mdx mice. In Sgcb-null mice, severe morphological disruption was present from 4 weeks in both quadriceps and diaphragm, and included conspicuous deposition of extracellular matrix components. Histopathological features of Sgcb-null mouse muscles were similar to those of age-matched mdx muscles at all ages examined, but, in the Sgcb-null mouse, the extent of connective tissue deposition was generally greater than mdx. Furthermore, in the Sgcb-null mouse, the amount of all three collagen isoforms increased steadily, while, in the mdx, they remained stable. We also found that, at 12 weeks, macrophages were significantly more numerous in mildly inflamed areas of Sgcb-null quadriceps compared to mdx quadriceps (but not in highly inflamed regions), while, in the diaphragm, macrophages did not differ significantly between the two models, in either region. Osteopontin mRNA was also significantly greater at 12 weeks in laser-dissected highly inflamed areas of the Sgcb-null quadriceps compared to the mdx quadriceps. TGF-β1 was present in areas of degeneration-regeneration, but levels were highly variable and in general did not differ significantly between the two models and controls. The roles of the various subtypes of macrophages in muscle repair and fibrosis in the two models require further study. The Sgcb-null mouse, which develops early fibrosis

  5. Current Structure and Non-Ideal Behavior at Magnetic Null Points in the Turbulent Magnetosheath

    Science.gov (United States)

    Wendel, D. E.; Adrian, M. L.

    2012-12-01

    The Poincaré index indicates the Cluster spacecraft tetrahedron entraps a number of magnetic nulls during an encounter with the turbulent magnetosheath. Previous researchers have found evidence for reconnection at one of the many filamentary current layers observed by Cluster in this region. We find that many of the entrained nulls are also associated with strong currents. We dissect the current structure of a pair of spiral nulls that may be topologically connected. At both nulls, we find a strong current along the spine, accompanied by a modest current perpendicular to the spine that tilts the axis of the spine toward the fan plane. At least one of the nulls manifests a non-ideal rotational flow pattern in the fan plane that is consistent with torsional spine reconnection as predicted by theory. These results emphasize the importance of examining the magnetic topology in interpreting the nature of currents and reconnection in three-dimensional turbulence.

  6. Current sheet formation and non-ideal behaviour at three-dimensional magnetic null points

    CERN Document Server

    Pontin, D I; Galsgaard, K

    2007-01-01

    The nature of the evolution of the magnetic field, and of current sheet formation, at three-dimensional (3D) magnetic null points is investigated. A kinematic example is presented which demonstrates that there is no possible choice of boundary conditions which renders the evolution of the field ideal at the null, when the ratios of the null eigenvalues are time-dependent. Resistive MHD simulations are described which demonstrate that this evolution is generic. A 3D null is subjected to boundary driving by shearing motions, and it is shown that a current sheet localised at the null is formed. The qualitative and quantitative properties of the current sheet are discussed. Accompanying the sheet development is the growth of a localised parallel electric field, one of the signatures of magnetic reconnection. Finally, the relevance of the results to a recent theory of turbulent reconnection are discussed.

  7. Continuous development of current sheets near and away from magnetic nulls

    Science.gov (United States)

    Kumar, Sanjay; Bhattacharyya, R.

    2016-04-01

    The presented computations compare the strength of current sheets which develop near and away from the magnetic nulls. To ensure the spontaneous generation of current sheets, the computations are performed congruently with Parker's magnetostatic theorem. The simulations evince current sheets near two dimensional and three dimensional magnetic nulls as well as away from them. An important finding of this work is in the demonstration of comparative scaling of peak current density with numerical resolution, for these different types of current sheets. The results document current sheets near two dimensional magnetic nulls to have larger strength while exhibiting a stronger scaling than the current sheets close to three dimensional magnetic nulls or away from any magnetic null. The comparative scaling points to a scenario where the magnetic topology near a developing current sheet is important for energetics of the subsequent reconnection.

  8. Computer generated hologram null test of a freeform optical surface with rectangular aperture

    Science.gov (United States)

    Su, Ping; Ma, Jianshe; Tan, Qiaofeng; Kang, Guoguo; Liu, Yi; Jin, Guofan

    2012-02-01

    In null computed generated hologram (CGH) test of optical elements, fitting method is needed in null CGH design to generate continuous phase function from the ray-traced discrete phase data. The null CGH for freeform testing usually has a deformed aperture and a high order phase function, because of the aberrations introduced by freeform wavefront propagation. With traditional Zernike polynomial fitting method, selection of an orthogonal basis set and choosing number of terms are needed before fitting. Zernike polynomial fitting method is not suitable in null CGH design for freeform testing; a novel CGH design method with cubic B-spline interpolation is developed. For a freeform surface with 18×18 mm2 rectangular aperture and 630 μm peak-to-valley undulation, the null CGH with a curved rectangular aperture is designed by using the method proposed. Simulation and experimental results proved the feasibility of the novel CGH design method.

  9. Proving the Achronal Averaged Null Energy Condition from the Generalized Second Law

    CERN Document Server

    Wall, Aron C

    2009-01-01

    A null line is a complete achronal null geodesic. It is proven that for any quantum fields minimally coupled to semiclassical Einstein gravity, the averaged null energy condition (ANEC) on null lines is a consequence of the generalized second law of thermodynamics for causal horizons. Auxiliary assumptions include CPT and the existence of a suitable renormalization scheme for the generalized entropy. Although the ANEC can be violated on general geodesics in curved spacetimes, as long as the ANEC holds on null lines there exist theorems showing that semiclassical gravity should satisfy positivity of energy, topological censorship, and should not admit closed timelike curves. It is pointed out that these theorems fail once the linearized graviton field is quantized, because then the renormalized shear squared term in the Raychaudhuri equation can be negative. A "shear-inclusive" generalization of the ANEC is proposed to remedy this, and is proven under an additional assumption about perturbations to horizons in...

  10. PSF and field of view characteristics of imaging and nulling interferometers

    Science.gov (United States)

    Hénault, François

    2010-07-01

    In this communication are presented some complements to a recent paper entitled "Simple Fourier optics formalism for high angular resolution systems and nulling interferometry" [1], dealing with imaging and nulling capacities of a few types of multi-aperture optical systems. Herein the characteristics of such systems in terms of Point Spread Function (PSF) and Field of View (FoV) are derived from simple analytical expressions that are further evaluated numerically for various configurations. We consider successively the general cases of Fizeau and Michelson interferometers, and those of a monolithic pupil, nulling telescope, of a nulling, Sheared-Pupil Telescope (SPT), and of a sparse aperture, Axially Combined Interferometer (ACI). The analytical formalism also allows establishing the exact Object-Image relationships applicable to nulling PSTs or ACIs that are planned for future space missions searching for habitable extra-solar planets.

  11. PSF and field of view characteristics of imaging and nulling interferometers

    CERN Document Server

    Hénault, François

    2010-01-01

    In this communication are presented some complements to a recent paper entitled "Simple Fourier optics formalism for high angular resolution systems and nulling interferometry", dealing with imaging and nulling capacities of a few types of multi-aperture optical systems. Herein the characteristics of such systems in terms of Point Spread Function (PSF) and Field of View (FoV) are derived from simple analytical expressions that are further evaluated numerically for various configurations. We consider successively the general cases of Fizeau and Michelson interferometers, and those of a monolithic pupil, nulling telescope, of a nulling, Sheared-Pupil Telescope (SPT), and of a sparse aperture, Axially Combined Interferometer (ACI). The analytical formalism also allows establishing the exact Object-Image relationships applicable to nulling PSTs or ACIs that are planned for future space missions searching for habitable extra-solar planets.

  12. Blind Null-space Tracking for MIMO Underlay Cognitive Radio Networks

    CERN Document Server

    Manolakos, Alexandros; Goldsmith, Andrea J

    2012-01-01

    Blind Null Space Learning (BNSL) has recently been proposed for fast and accurate learning of the null-space associated with the channel matrix between a secondary transmitter and a primary receiver. In this paper we propose a channel tracking enhancement of the algorithm, namely the Blind Null Space Tracking (BNST) algorithm that allows transmission of information to the Secondary Receiver (SR) while simultaneously learning the null-space of the time-varying target channel. Specifically, the enhanced algorithm initially performs a BNSL sweep in order to acquire the null space. Then, it performs modified Jacobi rotations such that the induced interference to the primary receiver is kept lower than a given threshold $P_{Th}$ with probability $p$ while information is transmitted to the SR simultaneously. We present simulation results indicating that the proposed approach has strictly better performance over the BNSL algorithm for channels with independent Rayleigh fading with a small Doppler frequency.

  13. A 3+1 perspective on null hypersurfaces and isolated horizons

    CERN Document Server

    Gourgoulhon, E

    2006-01-01

    The isolated horizon formalism recently introduced by Ashtekar et al. aims at providing a quasi-local concept of a black hole in equilibrium in an otherwise possibly dynamical spacetime. In this formalism, a hierarchy of geometrical structures is constructed on a null hypersurface. On the other side, the 3+1 formulation of general relativity provides a powerful setting for studying the spacetime dynamics, in particular gravitational radiation from black hole systems. We revisit the kinematics and dynamics of null hypersurfaces by making use of the 3+1 slicing. In particular, the additional structures induced on null hypersurfaces by the 3+1 slicing of spacetime permit a natural extension to the full spacetime of geometrical quantities defined on the null hypersurface. This 4-dimensional point of view facilitates the link between the null and spatial geometries. We proceed by reformulating the isolated horizon structure in this framework. We also reformulate previous works, such as Damour's black hole mechanic...

  14. Inheritance of 15 microsatellites in the Pacific oyster Crassostrea gigas: segregation and null allele identification for linkage analysis

    Institute of Scientific and Technical Information of China (English)

    LI Li; GUO Ximing; ZHANG Guofan

    2009-01-01

    Microsatellites were screened in a backcross family of the Pacific oyster, Crassostrea gigas. Fifteen microsatellite loci were distinguishable and polymorphic with 6 types of allele-combinations. Null alleles were detected in 46.7% of loci, accounting for 11.7% of the total alleles. Four loci did not segregate in Mendelian Ratios. Three linkage groups were identified among 7 of the 15 segregating loci. Fluorescence-based automated capillary electrophoresis (ABI 310 Genetic Analyzer) that used to detect the microsatellite loci, has been proved a fast, precise, and reliable method in microsatellite genotyping.

  15. Why Are Flare Ribbons Associated with the Spines of Magnetic Null Points Generically Elongated?

    Science.gov (United States)

    Pontin, David; Galsgaard, Klaus; Démoulin, Pascal

    2016-08-01

    Coronal magnetic null points exist in abundance, as demonstrated by extrapolations of the coronal field, and have been inferred to be important for a broad range of energetic events. These null points and their associated separatrix and spine field lines represent discontinuities of the field line mapping, making them preferential locations for reconnection. This field line mapping also exhibits strong gradients adjacent to the separatrix (fan) and spine field lines, which can be analysed using the "squashing factor", Q. In this article we analyse in detail the distribution of Q in the presence of magnetic nulls. While Q is formally infinite on both the spine and fan of the null, the decay of Q away from these structures is shown in general to depend strongly on the null-point structure. For the generic case of a non-radially-symmetric null, Q decays most slowly away from the spine or fan in the direction in which |{B}| increases most slowly. In particular, this demonstrates that the extended elliptical high-Q halo around the spine footpoints observed by Masson et al. ( Astrophys. J. 700, 559, 2009) is a generic feature. This extension of the Q halos around the spine or fan footpoints is important for diagnosing the regions of the photosphere that are magnetically connected to any current layer that forms at the null. In light of this, we discuss how our results can be used to interpret the geometry of observed flare ribbons in circular ribbon flares, in which typically a coronal null is implicated. We conclude that both the physics in the vicinity of the null and how this is related to the extension of Q away from the spine or fan can be used in tandem to understand observational signatures of reconnection at coronal null points.

  16. Electric currents in the solar atmosphere in the presence of magnetic null points

    Science.gov (United States)

    Carlo Santos, Jean; Büchner, Jörg; Otto, Antonius

    So far the role of magnetic null points in 3D reconnection was investigated mainly for the close vicinity of the null, with perturbations being applied at the nearby boundaries. In the solar atmosphere, however, electric currents are generated due to perturbations originating at the photosphere, far a way from coronal 3D nulls. We investigate the consequences of photospheric motion for the development of electric cur-rents in a coronal magnetic field configuration containing a null, located far away from the boundaries, and the influence of topological structures on their spatial distribution. We use a 3D resistive MHD code to investigate the consequences of photospheric plasma motion for the generation of currents in a coronal magnetic field containing a null. The plasma is consid-ered fully compressible and is initially in hydrostatic equilibrium. The initial magnetic field is current free (potential). Initially the photospheric plasma motion creates a magnetic field perturbation that propagates to the corona along the field lines at the local Alfvén speed. The shear Alfvenic wave pertur-e bation corresponds to a propagating current. The currents are mainly parallel to the magnetic field. The perturbations starting close to the foot points of the field lines that connect to the null eventually reach the vicinity of the null. Since the local Alfvén speed decreases as we approach the magnetic null point, the perturbations of the magnetic field never reach the null. Meanwhile, strong currents develop around the null point where the perturbations reach the intersection of two separatrices. On those regions, when there is an appropriate perturbation, a shear of the magnetic field is created in a length scale much smaller than the characteristic length scale of the system, generating a strong current channel.

  17. Gibberellins are involved in effect of near-null magnetic field on Arabidopsis flowering.

    Science.gov (United States)

    Xu, Chunxiao; Yu, Yang; Zhang, Yuxia; Li, Yue; Wei, Shufeng

    2017-01-01

    We previously found that flowering of Arabidopsis was suppressed by near-null magnetic field, which was related to the modification of cryptochrome. To disclose the physiological mechanism of this effect, we detected gibberellin (GA) levels and expressions of GA biosynthetic and signaling genes in wild type Arabidopsis plants and cryptochrome double mutant, cry1/cry2, grown in near-null magnetic field. We found that levels of GA4 , GA9 , GA34 , and GA51 in wild type plants in near-null magnetic field were significantly decreased compared with local geomagnetic field controls. However, GA levels in cry1/cry2 mutants in near-null magnetic field were similar to controls. Expressions of three GA20-oxidase (GA20ox) genes (GA20ox1, GA20ox2, and GA20ox3) and four GA3-oxidase (GA3ox) genes (GA3ox1, GA3ox2, GA3ox3, and GA3ox4) in wild type plants in near-null magnetic field were significantly reduced compared with controls, while expressions of GA20ox4, GA20ox5, GA2-oxidase (GA2ox) genes, and GA signaling-related genes in wild type plants in near-null magnetic field were not significantly different from controls. In contrast, expressions of all the detected GA biosynthetic and signaling genes in cry1/cry2 mutants were not affected by near-null magnetic field. Moreover, transcriptions of flowering-related genes, LFY and SOC1, in wild type plants were downregulated by near-null magnetic field, while they were not affected by near-null magnetic field in cry1/cry2 mutants. Our results suggest that the effect of near-null magnetic field on Arabidopsis flowering is GA-related, which is caused by cryptochrome-involved suppression of GA biosynthesis. Bioelectromagnetics. 38:1-10, 2017. © 2016 Wiley Periodicals, Inc.

  18. Abnormal Mammary Development in 129:STAT1-Null Mice is Stroma-Dependent.

    Science.gov (United States)

    Chen, Jane Q; Mori, Hidetoshi; Cardiff, Robert D; Trott, Josephine F; Hovey, Russell C; Hubbard, Neil E; Engelberg, Jesse A; Tepper, Clifford G; Willis, Brandon J; Khan, Imran H; Ravindran, Resmi K; Chan, Szeman R; Schreiber, Robert D; Borowsky, Alexander D

    2015-01-01

    Female 129:Stat1-null mice (129S6/SvEvTac-Stat1(tm1Rds) homozygous) uniquely develop estrogen-receptor (ER)-positive mammary tumors. Herein we report that the mammary glands (MG) of these mice have altered growth and development with abnormal terminal end buds alongside defective branching morphogenesis and ductal elongation. We also find that the 129:Stat1-null mammary fat pad (MFP) fails to sustain the growth of 129S6/SvEv wild-type and Stat1-null epithelium. These abnormalities are partially reversed by elevated serum progesterone and prolactin whereas transplantation of wild-type bone marrow into 129:Stat1-null mice does not reverse the MG developmental defects. Medium conditioned by 129:Stat1-null epithelium-cleared MFP does not stimulate epithelial proliferation, whereas it is stimulated by medium conditioned by epithelium-cleared MFP from either wild-type or 129:Stat1-null females having elevated progesterone and prolactin. Microarrays and multiplexed cytokine assays reveal that the MG of 129:Stat1-null mice has lower levels of growth factors that have been implicated in normal MG growth and development. Transplanted 129:Stat1-null tumors and their isolated cells also grow slower in 129:Stat1-null MG compared to wild-type recipient MG. These studies demonstrate that growth of normal and neoplastic 129:Stat1-null epithelium is dependent on the hormonal milieu and on factors from the mammary stroma such as cytokines. While the individual or combined effects of these factors remains to be resolved, our data supports the role of STAT1 in maintaining a tumor-suppressive MG microenvironment.

  19. Charged particle motion near a linear magnetic null

    Energy Technology Data Exchange (ETDEWEB)

    Kim, J.; Cary, J.R.

    1983-08-01

    Charged particle motion near the null of a two-dimensional magnetic field is studied. Specifically, the magnetic field is given by the vector potential A = zpsi/sub 0/((y/a)/sup 2/+(epsilonx/a)/sup 2/), in which psi/sub 0/,a, and epsilon are constants with epsilon parameterizing the ellipticity of the flux surfaces. Conservation of canonical z momentum p/sub z/ reduces the number of nontrivial degrees of freedom to two. Scaling reduces the number of parameters in the system to two, epsilon and sigma (the sign of p/sub z/ ). Analytical and numerical methods are used to study the nature of orbits. The results are expressed conveniently in terms of epsilon and Qequivalent(2mE)/sup 1/2//p/sub z/. When epsilon is unity, the additional symmetry implies integrability. When epsilon is less than unity (the case epsilon>1 is trivially related) three regimes are found: (1) For Vertical BarQVertical Bar>>1 particle orbits are regular, (2) for epsilon/sup 3/2/< or approx. =Vertical BarQVertical Bar< or approx. =1 most particle orbits are stochastic, and (3) for Vertical BarQVertical Bar<

  20. Magnetic flipping - Reconnection in three dimensions without null points

    Science.gov (United States)

    Priest, E. R.; Forbes, T. G.

    1992-01-01

    In three dimensions, magnetic reconnection may take place in a sheared magnetic field at any singular field line, where the nearby field has X-type topology in planes perpendicular to the field line and where an electric field is present parallel to the field line. In the ideal region around the singular line there will, in general, be singularities in the plasma flow and electric field, both at the singular line and at 'magnetic flipping layers', which are remnants of local magnetic separatrices. In the absence of a three-dimensional magnetic neutral point or null point, reconnection of field lines can still occur by a process of magnetic flipping, in which the plasma crosses the flipping layers but the field lines rapidly flip along them by magnetic diffusion. Depending on the boundary conditions, there may be two or four flipping layers which converge on the singular line. A boundary layer analysis of a flipping layer is given, in which the magnetic field parallel to the layer decreases as one crosses it while the plasma pressure (or magnetic pressure associated with the field along the singular line) increases. The width of the flipping layer decreases with distance from the singular line.

  1. Magnetic flipping: Reconnection in three-dimensions without null points

    Energy Technology Data Exchange (ETDEWEB)

    Priest, E.R.; Forbes, T.G. (Univ. of New Hampshire, Durham (United States))

    1992-02-01

    In three dimensions, magnetic reconnection may take place in a sheared magnetic field at any singular field line, where the nearby field has X-type topology in planes perpendicular to the field line and where an electric field is present parallel to the field line. In the ideal region around the singular line there will, in general, be singularities in the plasma flow and electric field, both at the singular line and at magnetic flipping layers, which are remnants of local magnetic separatrices. In the absence of a three-dimensional magnetic point or null point, reconnection of field lines can still occur by a process of magnetic flipping, in which the plasma crosses the flipping layers but the field lines rapidly flip along them by magnetic diffusion. Depending on the boundary conditions, there may be two or four flipping layers which converge on the singular line. A boundary layer analysis of a flipping layer is given, in which the magnetic field parallel to the layer decreases as one crosses it while the plasma pressure (or magnetic pressure associated with the field along the singular line) increases. The width of the flipping layer decreases with distance from the singular line.

  2. Strong subadditivity, null energy condition and charged black holes

    Energy Technology Data Exchange (ETDEWEB)

    Caceres, Elena [Facultad de Ciencias, Universidad de Colima,Bernal Diaz del Castillo 340, Colima (Mexico); Theory Group, Department of Physics, The University of Texas,Austin, TX 78712 (United States); Kundu, Arnab [Theory Group, Department of Physics, The University of Texas,Austin, TX 78712 (United States); Pedraza, Juan F.; Tangarife, Walter [Theory Group, Department of Physics, The University of Texas,Austin, TX 78712 (United States); Texas Cosmology Center, The University of Texas,Austin, TX 78712 (United States)

    2014-01-16

    Using the Hubeny-Rangamani-Takayanagi (HRT) conjectured formula for entanglement entropy in the context of the AdS/CFT correspondence with time-dependent backgrounds, we investigate the relation between the bulk null energy condition (NEC) of the stress-energy tensor with the strong sub-additivity (SSA) property of entanglement entropy in the boundary theory. In a background that interpolates between an AdS to an AdS-Reissner-Nordstrom-type geometry, we find that generically there always exists a critical surface beyond which the violation of NEC would naively occur. However, the extremal area surfaces that determine the entanglement entropy for the boundary theory, can penetrate into this forbidden region only for certain choices for the mass and the charge functions in the background. This penetration is then perceived as the violation of SSA in the boundary theory. We also find that this happens only when the critical surface lies above the apparent horizon, but not otherwise. We conjecture that SSA, which is thus non-trivially related to NEC, also characterizes the entire time-evolution process along which the dual field theory may thermalize.

  3. Metric-based Hamiltonians, null boundaries, and isolated horizons

    CERN Document Server

    Booth, I S

    2001-01-01

    We extend the quasilocal (metric-based) Hamiltonian formulation of general relativity so that it may be used to study regions of spacetime with null boundaries. In particular we use this generalized Brown-York formalism to study the physics of isolated horizons. We show that the first law of isolated horizon mechanics follows directly from the first variation of the Hamiltonian. This variation is not restricted to the phase space of solutions to the equations of motion but is instead through the space of all (off-shell) spacetimes that contain isolated horizons. We find two-surface integrals evaluated on the horizons that are consistent with the Hamiltonian and which define the energy and angular momentum of these objects. These are closely related to the corresponding Komar integrals and for Kerr-Newman spacetime are equal to the corresponding ADM/Bondi quantities. Thus, the energy of an isolated horizon calculated by this method is in agreement with that recently calculated by Ashtekar and collaborators but...

  4. Null Method’ Determination of Drug Biophase Concentration

    Science.gov (United States)

    Tallarida, Ronald J.; Lamarre, Neil

    2014-01-01

    PK/PD modeling is enhanced by improvements in the accuracy of its metrics. For PK/PD modeling of drugs and biologics that interact with enzymes or receptors, the equilibrium constant of the interaction can provide critical insight. Methodologies such as radioliogand binding and isolated tissue preparations can provide estimates of the equilibrium constants (as the dissociation constant, K value) for drugs and endogenous ligands that interact with specific enzymes and receptors. However, an impediment to further precision for PK/PD modeling is that it remains a problem to convert the concentration of drug in bulk solution (A) into an estimate of receptor occupation, since A is not necessarily the concentration (C) of drug in the biophase that yields fractional binding from the law of mass action, viz., C/(C + K). In most experimental studies A is much larger than K, so the use of administered instead of biophase concentration gives fractional occupancies very close to unity. We here provide a simple way to obtain an estimate of the factor that converts the total drug concentration into the biophase concentration in isolated tissue preparation. Our approach is an extension of the now classic ‘null method’ introduced and applied by Furchgott to determination of drug-receptor dissociation constants. PMID:22037914

  5. Muscular dystrophy in PTFR/cavin-1 null mice

    Science.gov (United States)

    Ding, Shi-Ying; Pilch, Paul F.

    2017-01-01

    ice and humans lacking the caveolae component polymerase I transcription release factor (PTRF, also known as cavin-1) exhibit lipo- and muscular dystrophy. Here we describe the molecular features underlying the muscle phenotype for PTRF/cavin-1 null mice. These animals had a decreased ability to exercise, and exhibited muscle hypertrophy with increased muscle fiber size and muscle mass due, in part, to constitutive activation of the Akt pathway. Their muscles were fibrotic and exhibited impaired membrane integrity accompanied by an apparent compensatory activation of the dystrophin-glycoprotein complex along with elevated expression of proteins involved in muscle repair function. Ptrf deletion also caused decreased mitochondrial function, oxygen consumption, and altered myofiber composition. Thus, in addition to compromised adipocyte-related physiology, the absence of PTRF/cavin-1 in mice caused a unique form of muscular dystrophy with a phenotype similar or identical to that seen in humans lacking this protein. Further understanding of this muscular dystrophy model will provide information relevant to the human situation and guidance for potential therapies.

  6. A null relationship between media multitasking and well-being.

    Directory of Open Access Journals (Sweden)

    Shui-I Shih

    Full Text Available There is a rapidly increasing trend in media-media multitasking or MMM (using two or more media concurrently. In a recent conference, scholars from diverse disciplines expressed concerns that indulgence in MMM may compromise well-being and/or cognitive abilities. However, research on MMM's impacts is too sparse to inform the general public and policy makers whether MMM should be encouraged, managed, or minimized. The primary purpose of the present study was to develop an innovative computerized instrument--the Survey of the Previous Day (SPD--to quantify MMM as well as media-nonmedia and nonmedia-nonmedia multitasking and sole-tasking. The secondary purpose was to examine whether these indices could predict a sample of well-being related, psychosocial measures. In the SPD, participants first recalled (typed what they did during each hour of the previous day. In later parts of the SPD, participants analysed activities and their timing and duration for each hour of the previous day, while relevant recall was on display. Participants also completed the Media Use Questionnaire. The results showed non-significant relationship between tasking measures and well-being related measures. Given how little is known about the associations between MMM and well-being, the null results may offer some general reassurance to those who are apprehensive about negative impacts of MMM.

  7. Strong Subadditivity, Null Energy Condition and Charged Black Holes

    CERN Document Server

    Caceres, Elena; Pedraza, Juan F; Tangarife, Walter

    2014-01-01

    Using the Hubeny-Rangamani-Takayanagi (HRT) conjectured formula for entanglement entropy in the context of the AdS/CFT correspondence with time-dependent backgrounds, we investigate the relation between the bulk null energy condition (NEC) of the stress-energy tensor with the strong sub-additivity (SSA) property of entanglement entropy in the boundary theory. In a background that interpolates between an AdS to an AdS-Reissner-Nordstrom-type geometry, we find that generically there always exists a critical surface beyond which the violation of NEC would naively occur. However, the extremal area surfaces that determine the entanglement entropy for the boundary theory, can penetrate into this forbidden region only for certain choices for the mass and the charge functions in the background. This penetration is then perceived as the violation of SSA in the boundary theory. We also find that this happens only when the critical surface lies above the apparent horizon, but not otherwise. We conjecture that SSA, which...

  8. Aspects of QCD current algebra on a null plane

    Science.gov (United States)

    Beane, S. R.; Hobbs, T. J.

    2016-09-01

    Consequences of QCD current algebra formulated on a light-like hyperplane are derived for the forward scattering of vector and axial-vector currents on an arbitrary hadronic target. It is shown that current algebra gives rise to a special class of sum rules that are direct consequences of the independent chiral symmetry that exists at every point on the two-dimensional transverse plane orthogonal to the lightlike direction. These sum rules are obtained by exploiting the closed, infinite-dimensional algebra satisfied by the transverse moments of null-plane axial-vector and vector charge distributions. In the special case of a nucleon target, this procedure leads to the Adler-Weisberger, Gerasimov-Drell-Hearn, Cabibbo-Radicati and Fubini-Furlan-Rossetti sum rules. Matching to the dispersion-theoretic language which is usually invoked in deriving these sum rules, the moment sum rules are shown to be equivalent to algebraic constraints on forward S-matrix elements in the Regge limit.

  9. Genetic variants and increased risk of meningioma: an updated meta-analysis

    Science.gov (United States)

    Han, Xiao-Yong; Wang, Wei; Wang, Lei-Lei; Wang, Xi-Rui; Li, Gang

    2017-01-01

    Purpose Various genetic variants have been reported to be linked to an increased risk of meningioma. However, no confirmed conclusion has been obtained. The purpose of the study was to investigate potential meningioma-associated gene polymorphisms, based on published evidence. Materials and methods An updated meta-analysis was performed in September 2016. After electronic database searching and study screening, we selected eligible case-control studies and extracted data for meta-analysis, using Mantel–Haenszel statistics. P-values, pooled odds ratios (ORs), and 95% confidence intervals were calculated. Results We finally selected eight genes with ten polymorphisms: MLLT10 rs12770228, CASP8 rs1045485, XRCC1 rs1799782, rs25487, MTHFR rs1801133, rs1801131, MTRR rs1801394, MTR rs1805087, GSTM1 null/present, and GSTT1 null/present. Results of meta-analyses showed that there was increased meningioma risk in case groups under all models of MLLT10 rs12770228 (all OR >1, P1, P1, P<0.05). However, no significantly increased meningioma risks were observed for CASP8 rs1045485, XRCC1 rs25487, rs1799782, MTHFR rs1801133, MTR rs1805087, or GSTM1/GSTT1 null mutations. Conclusion Our updated meta-analysis provided statistical evidence for the role of MLLT10 rs12770228, MTRR rs1801394, and MTHFR rs1801131 in increased susceptibility to meningioma. PMID:28405167

  10. Suppression of Arabidopsis flowering by near-null magnetic field is affected by light.

    Science.gov (United States)

    Xu, Chunxiao; Li, Yue; Yu, Yang; Zhang, Yuxia; Wei, Shufeng

    2015-09-01

    We previously reported that a near-null magnetic field suppressed Arabidopsis flowering in white light, which might be related to the function modification of cryptochrome (CRY). To further demonstrate that the effect of near-null magnetic field on Arabidopsis flowering is associated with CRY, Arabidopsis wild type and CRY mutant plants were grown in the near-null magnetic field under blue or red light with different light cycle and photosynthetic photon flux density. We found that Arabidopsis flowering was significantly suppressed by near-null magnetic field in blue light with lower intensity (10 µmol/m(2) /s) and shorter cycle (12 h period: 6 h light/6 h dark). However, flowering time of CRY1/CRY2 mutants did not show any difference between plants grown in near-null magnetic field and in local geomagnetic field under detected light conditions. In red light, no significant difference was shown in Arabidopsis flowering between plants in near-null magnetic field and local geomagnetic field under detected light cycles and intensities. These results suggest that changes of blue light cycle and intensity alter the effect of near-null magnetic field on Arabidopsis flowering, which is mediated by CRY.

  11. Why are flare ribbons generically elongated in configurations with magnetic null points?

    Science.gov (United States)

    Pontin, David Iain; Galsgaard, Klaus; Demoulin, Pascal

    2016-05-01

    Coronal magnetic null points exist in abundance as demonstrated by extrapolations of the coronal field, and have been inferred to be important for a broad range of energetic events. These null points and their associated separatrix and spine field lines represent discontinuities of the field line mapping, making them preferential locations for reconnection in the corona. In addition, the field line mapping in the vicinity of these null points exhibits strong gradients as measured by the “squashing factor”, Q. We demonstrate that the extension of the Q halos around the spine/fan footpoints is in general important for diagnosing the regions of the photosphere that are magnetically connected to any current layer that forms at the null. In light of this, we discuss the extent to which our results can be used to interpret the geometry of observed flare ribbons in events in which a coronal null is implicated. We conclude that together the physics in the vicinity of the null and how this is related to the extension of Q away from the spine/fan can be used in tandem to understand observational signatures of reconnection at coronal null points.

  12. Shocks and currents in stratified atmospheres with a magnetic null point

    Science.gov (United States)

    Tarr, Lucas A.; Linton, Mark

    2017-08-01

    We use the resistive MHD code LARE (Arber et al 2001) to inject a compressive MHD wavepacket into a stratified atmosphere that has a single magnetic null point, as recently described in Tarr et al 2017. The 2.5D simulation represents a slice through a small ephemeral region or area of plage. The strong gradients in field strength and connectivity related to the presence of the null produce substantially different dynamics compared to the more slowly varying fields typically used in simple sunspot models. The wave-null interaction produces a fast mode shock that collapses the null into a current sheet and generates a set of outward propagating (from the null) slow mode shocks confined to field lines near each separatrix. A combination of oscillatory reconnection and shock dissipation ultimately raise the plasma's internal energy at the null and along each separatrix by 25-50% above the background. The resulting pressure gradients must be balanced by Lorentz forces, so that the final state has contact discontinuities along each separatrix and a persistent current at the null. The simulation demonstrates that fast and slow mode waves localize currents to the topologically important locations of the field, just as their Alfvenic counterparts do, and also illustrates the necessity of treating waves and reconnection as coupled phenomena.

  13. Rac-null leukocytes are associated with increased inflammation-mediated alveolar bone loss.

    Science.gov (United States)

    Sima, Corneliu; Gastfreund, Shoshi; Sun, Chunxiang; Glogauer, Michael

    2014-02-01

    Periodontitis is characterized by altered host-biofilm interactions that result in irreversible inflammation-mediated alveolar bone loss. Genetic and epigenetic factors that predispose to ineffective control of biofilm composition and maintenance of tissue homeostasis are not fully understood. We elucidated how leukocytes affect the course of periodontitis in Rac-null mice. Mouse models of acute gingivitis and periodontitis were used to assess the early inflammatory response and patterns of chronicity leading to loss of alveolar bone due to inflammation in Rac-null mice. Leukocyte margination was differentially impaired in these mice during attachment in conditional Rac1-null (granulocyte/monocyte lineage) mice and during rolling and attachment in Rac2-null (all blood cells) mice. Inflammatory responses to subgingival ligatures, assessed by changes in peripheral blood differential leukocyte numbers, were altered in Rac-null compared with wild-type mice. In response to persistent subgingival ligature-mediated challenge, Rac-null mice had increased loss of alveolar bone with patterns of resorption characteristic of aggressive forms of periodontitis. These findings were partially explained by higher osteoclastic coverage of the bone-periodontal ligament interface in Rac-null compared with wild-type mice. In conclusion, this study demonstrates that leukocyte defects, such as decreased endothelial margination and tissue recruitment, are rate-limiting steps in the periodontal inflammatory process that lead to more aggressive forms of periodontitis.

  14. Observation of Magnetic Reconnection at a 3D Null Point Associated with a Solar Eruption

    Science.gov (United States)

    Sun, J. Q.; Zhang, J.; Yang, K.; Cheng, X.; Ding, M. D.

    2016-10-01

    Magnetic null has long been recognized as a special structure serving as a preferential site for magnetic reconnection (MR). However, the direct observational study of MR at null-points is largely lacking. Here, we show the observations of MR around a magnetic null associated with an eruption that resulted in an M1.7 flare and a coronal mass ejection. The Geostationary Operational Environmental Satellites X-ray profile of the flare exhibited two peaks at ∼02:23 UT and ∼02:40 UT on 2012 November 8, respectively. Based on the imaging observations, we find that the first and also primary X-ray peak was originated from MR in the current sheet (CS) underneath the erupting magnetic flux rope (MFR). On the other hand, the second and also weaker X-ray peak was caused by MR around a null point located above the pre-eruption MFR. The interaction of the null point and the erupting MFR can be described as a two-step process. During the first step, the erupting and fast expanding MFR passed through the null point, resulting in a significant displacement of the magnetic field surrounding the null. During the second step, the displaced magnetic field started to move back, resulting in a converging inflow and subsequently the MR around the null. The null-point reconnection is a different process from the current sheet reconnection in this flare; the latter is the cause of the main peak of the flare, while the former is the cause of the secondary peak of the flare and the conspicuous high-lying cusp structure.

  15. Magnetoacoustic Waves in a Stratified Atmosphere with a Magnetic Null Point

    Science.gov (United States)

    Tarr, Lucas A.; Linton, Mark; Leake, James

    2017-03-01

    We perform nonlinear MHD simulations to study the propagation of magnetoacoustic waves from the photosphere to the low corona. We focus on a 2D system with a gravitationally stratified atmosphere and three photospheric concentrations of magnetic flux that produce a magnetic null point with a magnetic dome topology. We find that a single wavepacket introduced at the lower boundary splits into multiple secondary wavepackets. A portion of the packet refracts toward the null owing to the varying Alfvén speed. Waves incident on the equipartition contour surrounding the null, where the sound and Alfvén speeds coincide, partially transmit, reflect, and mode-convert between branches of the local dispersion relation. Approximately 15.5% of the wavepacket’s initial energy (E input) converges on the null, mostly as a fast magnetoacoustic wave. Conversion is very efficient: 70% of the energy incident on the null is converted to slow modes propagating away from the null, 7% leaves as a fast wave, and the remaining 23% (0.036E input) is locally dissipated. The acoustic energy leaving the null is strongly concentrated along field lines near each of the null’s four separatrices. The portion of the wavepacket that refracts toward the null, and the amount of current accumulation, depends on the vertical and horizontal wavenumbers and the centroid position of the wavepacket as it crosses the photosphere. Regions that refract toward or away from the null do not simply coincide with regions of open versus closed magnetic field or regions of particular field orientation. We also model wavepacket propagation using a WKB method and find that it agrees qualitatively, though not quantitatively, with the results of the numerical simulation.

  16. Reliability assessment of null allele detection: inconsistencies between and within different methods.

    Science.gov (United States)

    Dąbrowski, M J; Pilot, M; Kruczyk, M; Żmihorski, M; Umer, H M; Gliwicz, J

    2014-03-01

    Microsatellite loci are widely used in population genetic studies, but the presence of null alleles may lead to biased results. Here, we assessed five methods that indirectly detect null alleles and found large inconsistencies among them. Our analysis was based on 20 microsatellite loci genotyped in a natural population of Microtus oeconomus sampled during 8 years, together with 1200 simulated populations without null alleles, but experiencing bottlenecks of varying duration and intensity, and 120 simulated populations with known null alleles. In the natural population, 29% of positive results were consistent between the methods in pairwise comparisons, and in the simulated data set, this proportion was 14%. The positive results were also inconsistent between different years in the natural population. In the null-allele-free simulated data set, the number of false positives increased with increased bottleneck intensity and duration. We also found a low concordance in null allele detection between the original simulated populations and their 20% random subsets. In the populations simulated to include null alleles, between 22% and 42% of true null alleles remained undetected, which highlighted that detection errors are not restricted to false positives. None of the evaluated methods clearly outperformed the others when both false-positive and false-negative rates were considered. Accepting only the positive results consistent between at least two methods should considerably reduce the false-positive rate, but this approach may increase the false-negative rate. Our study demonstrates the need for novel null allele detection methods that could be reliably applied to natural populations.

  17. Low frequency of filaggrin null mutations in Croatia and their relation with allergic diseases.

    Science.gov (United States)

    Sabolić Pipinić, I; Varnai, V M; Turk, R; Breljak, D; Kezić, S; Macan, J

    2013-06-01

    Filaggrin gene (FLG) null mutations are considered associated with atopic dermatitis. This study was conducted to determine the prevalence of FLG null mutations R501X, 2282del4, R2447X and S3247X in the Croatian population and their role in the occurrence of allergic diseases including atopic dermatitis, allergic rhinitis, asthma and allergic contact dermatitis (ACD). Study enrolled 440 freshmen with defined allergic diseases by means of both present symptoms in International Study of Asthma and Allergies in Childhood questionnaire (relevant respiratory and/or skin symptoms) and markers of allergic sensitization (positive skin prick and/or patch test). FLG null mutations were successfully genotyped in 423 students of which 11 (2.6%) were carriers of FLG null mutation: 1/423 (0.2%) was heterozygous for R501X and 10/423 (2.4%) were heterozygous for 2282del4. No carriers of R2447X and S3247X mutations were identified. In wild-type FLG carriers (412 subjects), atopic dermatitis was present in 45 (11%), allergic rhinitis in 70 (17%) and allergic asthma in 29 (7%) students. Twenty-five of 393 (7%) patch-tested wild-type FLG carriers had ACD. Among 11 FLG null mutation carriers, four had one or more allergic diseases, and five had reported skin symptoms without defined allergic sensitization (positive skin prick test and/or patch test). FLG null mutations were not confirmed as a predictor of analysed allergic diseases, but were confirmed as an independent predictor of skin symptoms (OR 17.19, 95% CI 3.41-86.6, P null mutations in the studied Croatian population supporting a theory of a latitude-dependent distribution of FGL null mutations in Europe, with a decreasing north-south gradient of R501X and 2282del4 mutation frequency. The relation between FLG null mutations and skin disorders was confirmed.

  18. 'True' null allele detection in microsatellite loci: a comparison of methods, assessment of difficulties and survey of possible improvements.

    Science.gov (United States)

    Dąbrowski, M J; Bornelöv, S; Kruczyk, M; Baltzer, N; Komorowski, J

    2015-05-01

    Null alleles are alleles that for various reasons fail to amplify in a PCR assay. The presence of null alleles in microsatellite data is known to bias the genetic parameter estimates. Thus, efficient detection of null alleles is crucial, but the methods available for indirect null allele detection return inconsistent results. Here, our aim was to compare different methods for null allele detection, to explain their respective performance and to provide improvements. We applied several approaches to identify the 'true' null alleles based on the predictions made by five different methods, used either individually or in combination. First, we introduced simulated 'true' null alleles into 240 population data sets and applied the methods to measure their success in detecting the simulated null alleles. The single best-performing method was ML-NullFreq_frequency. Furthermore, we applied different noise reduction approaches to improve the results. For instance, by combining the results of several methods, we obtained more reliable results than using a single one. Rule-based classification was applied to identify population properties linked to the false discovery rate. Rules obtained from the classifier described which population genetic estimates and loci characteristics were linked to the success of each method. We have shown that by simulating 'true' null alleles into a population data set, we may define a null allele frequency threshold, related to a desired true or false discovery rate. Moreover, using such simulated data sets, the expected null allele homozygote frequency may be estimated independently of the equilibrium state of the population.

  19. Tangential and sagittal curvature from the normals computed by the null screen method in corneal topography

    Science.gov (United States)

    Estrada-Molina, Amilcar; Díaz-Uribe, Rufino

    2011-08-01

    A new method for computing the tangential and sagittal curvatures from the normals to a cornea is proposed. The normals are obtained through a Null Screen method from the coordinates of the drops shaped spots at the null screen, the coordinates on a reference approximating surface and the centroids on the image plane. This method assumes that the cornea has rotational symmetry and our derivations will be carried out in the meridional plane that contains the symmetry axis. Experimental results are shown for a calibration spherical surface, using cylindrical null screens with radial point arrays.

  20. Simple computation of null-geodesics, with applications to vortex boundary detection

    Science.gov (United States)

    Serra, Mattia; Haller, George

    2016-11-01

    Recent results show that boundaries of coherent vortices (elliptic coherent structures) can be computed as closed null-geodesics of appropriate Lorentzian metrics defined on the physical domain of the underlying fluid. Here we derive a new method for computing null-geodesics of general Lorentzian metrics, founded on the geometry of geodesic flows. We also derive the correct set of initial conditions for the computation of closed null-geodesics, based on simple topological properties of planar closed curves. This makes the computation of coherent vortex boundaries fully automated, simpler and more accurate compared to the existing procedure. As an illustration, we compute objective coherent vortex boundaries in Oceanic and Atmospheric Flows.