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Association Between the Fatigue and Sleep Quality of Kidney Transplant Recipients: The Mediating Role of Rumination. J Nerv Ment Dis 2023; 211:23-28. [PMID: 35926188 DOI: 10.1097/nmd.0000000000001564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
ABSTRACT Sleep disorders persist in renal transplant patients. Previous studies have showed that fatigue and rumination are an important determinant of sleep quality. However, very few studies have explored the mediating role of rumination in the relationship between fatigue and sleep quality in kidney transplant recipients. A descriptive cross-sectional research design was implemented, and 192 kidney transplant patients completed the short questionnaire about their recent experiences of fatigue, rumination, and sleep quality. The prevalence of sleep disorders among kidney transplant recipients was 19.3%. With rumination as a partial mediator, fatigue indirectly affected the patients' sleep quality. This indirect effect was 0.10 (95% confidence interval, 0.154-0.419). Our results indicate that the incidence of sleep disorders after renal transplantation was high, and the more tired kidney transplant recipients become, the more likely they are to ruminate, which leads to a decline in sleep quality.
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miR-1293 Suppresses Tumor Malignancy by Targeting Hydrocyanic Oxidase 2: Therapeutic Potential of a miR-1293/Hydrocyanic Oxidase 2 Axis in Renal Cell Carcinoma. Cancer Biother Radiopharm 2020; 35:377-386. [PMID: 31971830 DOI: 10.1089/cbr.2019.2957] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Renal cell carcinoma (RCC) is a common cancer, and extensive research suggests that microRNA may play an important role in the progression of RCC. The emphasis of this article was to reveal the function and mechanism of microRNA-1293(miR-1293) in the development of RCC tumors. First, the authors carried out bioinformatics analysis. The differential expression of miR-1293 in RCC tumor and normal cells was analyzed using the data from The Cancer Genome Atlas database, and Kaplan-Meier survival analysis was carried out to test the survival rate. Subsequently, the miR-1293 expression in RCC cell lines was examined by quantitative real-time PCR. Then Cell counting kit-8 and Transwell assays were executed to detect the function of miR-1293 in RCC. Bioinformatics prediction, western blotting, and dual-luciferase reporter assay were set to check the target gene of miR-1293. Finally, they conducted rescue experiments to verify whether the regulation of miR-1293 on the biological function of RCC cells was achieved by regulating hydrocyanic oxidase 2 (HAO2). Bioinformatics results showed that miR-1293 was highly expressed in RCC, and the miR-1293 high-expression group showed a lower survival rate than the miR-1293 low-expression group, which suggested that the high expression of miR-1293 was related to unfavorable prognosis in RCC. Subsequent assays evidenced that upregulation of miR-1293 expression significantly increased the cell viability and promoted cell migration and invasion in RCC. Silencing miR-1293 expression showed opposite results. Furthermore, HAO2 was confirmed to be a direct target gene of miR-1293 by dual-luciferase reporter assay, and miR-1293 negatively regulated the expression of HAO2. Moreover, rescue experiments evidenced that miR-1293 reduced the cell viability, invasion, and migration of RCC by regulating HAO2. In sum, miR-1293 can regulate the viability, invasion, and migration of RCC tumor cells by targeting HAO2, suggesting that miR-1293 can be used as a new biomarker for clinical treatment of RCC.
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[A cross-sectional survey of receiving no methadone maintenance treatment in HIV infected injecting drug users in Dehong Dai and Jingpo autonomous prefecture, Yunnan province]. ZHONGHUA LIU XING BING XUE ZA ZHI = ZHONGHUA LIUXINGBINGXUE ZAZHI 2017; 38:336-340. [PMID: 28329935 DOI: 10.3760/cma.j.issn.0254-6450.2017.03.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Objective: To understand the current status of receiving no methadone maintenance treatment (MMT) and influencing factors in HIV infected injecting drug users (IDUs) in Dehong Dai and Jingpo autonomous prefectures, Yunnan province. Methods: Data of survival of IDUs with AIDS in Dehong were collected from " Chinese National Comprehensive HIV/AIDS and Care Information System" in December, 2014. Results: There were 987 IDUs who should receive MMT, the majority of them were males (94.6%, 934/987), aged 35-44 years (53.0%, 523/987) and farmers (77.2%, 762/987). Among the 987 IDUs, 60.2% (592/987) received no MMT. Multivariate logistic regression analysis showed that being female (OR=2.66, 95%CI: 1.21-5.87), in Jingpo ethnic group (OR=3.05, 95% CI: 1.97-4.71) were the major risk factors for receiving no MMT; not being farmers (OR=0.46, 95%CI: 0.31-0.70), in Dai ethnic group (OR=0.53, 95%CI: 0.36-0.79), diagnosed HIV infection history ≥10 years (OR=0.60, 95%CI: 0.45-0.81) were the major protective factors for receiving no MMT. The reasons for receiving no MMT included long distance journey (289, 48.8%), fear of exposure (124, 20.9%), poor daily medication compliance (59, 10.0%), fear of side effects (47, 7.9%), others (73, 12.3%). Conclusions: The proportion of receiving no MMT in IDUs with AIDS in Dehong was high. Being female and farmer, in Jingpo ethnic group, low educational level, short diagnosed HIV infection history were influencing factors for receiving no MMT. The effective intervention measures should be taken to further improve MMT coverage according to the different characteristics of the patients.
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Predictive factors for open conversion of laparoscopic adrenalectomy: a 13-year review of 456 cases. J Endourol 2008; 21:1333-7. [PMID: 18042025 DOI: 10.1089/end.2006.450] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND AND PURPOSE Laparoscopic adrenalectomy has largely replaced open adrenalectomy for the treatment of adrenal tumor. However, certain cases still require conversion to open procedures. Identifying the risk of conversion remains difficult. This study identified risk factors that may predict conversion from a laparoscopic to an open procedure. PATIENTS AND METHODS From January 1993 to September 2006, a total of 456 laparoscopic adrenalectomies were performed at two urologic centers. A retrospective analysis of parameters, including tumor size, patient age, American Society of Anesthesiology classification, body mass index (BMI), sex, laparoscopic approach, previous abdominal surgery, laterality, type of tumor, laparoscopist experience, and surgeon, was performed. Multivariate logistic regression was used to identify those variables predicting conversion. RESULTS A total of 25 (5.5%) laparoscopic adrenalectomies required conversion. Significant predictors of conversion according to univariate analysis were tumor size > or =5 cm, BMI > or =24 kg/m(2), and pheochromocytoma. Multivariate analysis showed that the significant independent predictive factors for conversion were tumor size > or =5 cm (8.884 greater odds ratio [OR] of conversion; 95% confidence interval 3.543, 22.277; P < 0.001), BMI > or = 24 kg/m(2) (OR 3.632; 95% confidence interval 1.367, 9.648; P = 0.010), and pheochromocytoma (OR 3.068; 95% confidence interval 1.175, 8.007; P = 0.022). CONCLUSIONS Knowledge of tumor size, BMI, and tumor type can help in counseling patients undergoing laparoscopic adrenalectomy with regard to the probability of conversion. The size of the tumor was found to be the most important predictor.
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The E-cadherin gene polymorphism 160C->A and cancer risk: A HuGE review and meta-analysis of 26 case-control studies. Am J Epidemiol 2008; 167:7-14. [PMID: 17971340 DOI: 10.1093/aje/kwm264] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
A single nucleotide polymorphism, - 160C-->A, has been identified in the promoter region of the E-cadherin gene and has been shown to alter its transcriptional activity. To assess susceptibility of -160A allele carriers to seven types of cancers, the authors conducted a comprehensive meta-analysis, up to November 2006, of 26 case-control studies comprising 7,042 cases and 7,011 controls. Pooled odds ratios and 95% confidence intervals were calculated by using the random-effects model. Publication bias, subgroup, and sensitivity analyses were also performed, which showed that -160A allele carriers, compared with noncarriers, had about a 17-19% increased risk of several invasive/metastatic tumors. Analyses of various types of cancers revealed that, in Europeans, the -160AA homozygote was associated with an increased risk of urothelial cancer, carriers of -160A were at increased risk of lung and prostate cancers, and carriers of -160A with gastric cancer were found to suffer a significantly increased risk, whereas their Asian counterparts seemed to be tolerant. No evidence was found that the -160A allele predisposed its carriers to breast, colorectal, or esophageal cancers. These findings indicate that -160A of the E-cadherin gene is emerging as a low-penetrance tumor susceptibility allele for the development of gastric, lung, prostate, and urothelial cancers.
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High frequency of level II-V lymph node involvement in RET/PTC positive papillary thyroid carcinoma. Eur J Surg Oncol 2007; 34:77-81. [PMID: 17954023 DOI: 10.1016/j.ejso.2007.08.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2007] [Accepted: 08/28/2007] [Indexed: 10/22/2022] Open
Abstract
AIMS To investigate the frequency and clinical significance of RET rearrangement in Chinese patients with papillary thyroid carcinoma (PTC) and discuss the role of RET rearrangement in therapeutic decision-making after the performance of level VI lymph node dissection and the 2002 AJCC staging system. METHODS RET/PTC-1 and RET/PTC-3 were detected in 126 PTCs using reverse transcription-polymerase chain reaction (RT-PCR) and direct sequencing. RESULTS RET rearrangement was detected in 18 cases of PTC. The patient group aged < 20 years had the highest frequency (3/6) of RET rearrangement among the age groups (< 20 years, 20-40 years and > or = 40 years; P=0.03). RET/PTC-1 positive patients were more likely to suffer from Hashimoto's thyroiditis simultaneously (P=0.02) while RET/PTC-3 positive patients had a higher frequency of extrathyroidal extension (P<0.01) and advanced T classification (P<0.01). RET rearrangement (OR=8.70, 95% CI 1.69-44.81), male (OR=3.88, 95% CI 1.41-10.69), age (OR=0.96, 95% CI 0.93-0.99), multifocality (OR=3.54, 95% CI 1.33-9.41) and advanced T classification (OR=7.32, 95% CI 2.91-18.40) were all identified as risk factors of level II-V lymph node involvement in the multivariate analysis. CONCLUSIONS The frequency of RET rearrangement in Chinese patients is low and age related. RET/PTC-1 and RET/PTC-3 are associated with different clinical pathological characteristics but not with lymph node involvement. The RET/PTC positive patients should receive more attention to lateral neck in the management of PTC.
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Abstract
Uncovering genetic control of variation in ethanol tolerance in natural populations of yeast Saccharomyces cerevisiae is essential for understanding the evolution of fermentation, the dominant lifestyle of the species, and for improving efficiency of selection for strains with high ethanol tolerance, a character of great economic value for the brewing and biofuel industries. To date, as many as 251 genes have been predicted to be involved in influencing this character. Candidacy of these genes was determined from a tested phenotypic effect following gene knockout, from an induced change in gene function under an ethanol stress condition, or by mutagenesis. This article represents the first genomics approach for dissecting genetic variation in ethanol tolerance between two yeast strains with a highly divergent trait phenotype. We developed a simple but reliable experimental protocol for scoring the phenotype and a set of STR/SNP markers evenly covering the whole genome. We created a mapping population comprising 319 segregants from crossing the parental strains. On the basis of the data sets, we find that the tolerance trait has a high heritability and that additive genetic variance dominates genetic variation of the trait. Segregation at five QTL detected has explained approximately 50% of phenotypic variation; in particular, the major QTL mapped on yeast chromosome 9 has accounted for a quarter of the phenotypic variation. We integrated the QTL analysis with the predicted candidacy of ethanol resistance genes and found that only a few of these candidates fall in the QTL regions.
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Comparative proteomics of apoptosis initiation induced by 5-fluorouracil in human gastric cancer. CHINESE J PHYSIOL 2006; 49:31-8. [PMID: 16900703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/11/2023] Open
Abstract
5-Fluorouracil is the first choice chemotherapeutic drug for patients with gastric cancer, but the mechanism that 5-fluorouracil plays the anti-tumor role remains unclear. The aim of this study was to clarify correlated [corrected] proteins induced by 5-fluorouracil in the apoptosis-initiation of human gastric cancer (MGC-803) cells. The time point of apoptosis-initiation induced by 5-fluorouracil in MGC-803 cells was determinated using 5-fluorouracil-withdrawal. Two-dimensional electrophoreses (2-DE) were employed to compare the differentials of protein expressions of the MGC-803 cells at the apoptosis-initiation phase and those of the MGC-803 cells untreated with 5-fluorouracil. The differential proteins included 14 upregulated proteins and 8 downregulated proteins. They indicated a more-than-doubled alteration. These proteins were digested in gels by trypsin and the mass of generated peptides were measured by matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS). The data obtained from peptide mass fingerprinting (PMF) were searched out using the internet available database mascot (http://www.matrixscience.com). The results showed that proteomics analyses have evidenced that many kinds of proteins are involved in the apoptosis initiation of human gastric cancer MGC-803 cells. These proteins are related to metabolism, oxidation, cytoskeleton and signal transduction and other aspects of cells. In conclusion, the experiment model of apoptosis-initiation of human gastric cancer MGC-803 cells induced by 5-fluorouracil based on proteomic analysis has been established, giving an impetus to researches of the mechanism of apoptosis in human gastric cancer, and laying a foundation for the selection of potential drug precursors specific for inducing apoptosis-initiation in human gastric cancer.
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Abstract
An international consortium has launched the whole-genome sequencing of potato, the fourth most important food crop in the world. Construction of genetic linkage maps is an inevitable step for taking advantage of the genome projects for the development of novel cultivars in the autotetraploid crop species. However, linkage analysis in autopolyploids, the kernel of linkage map construction, is theoretically challenging and methodologically unavailable in the current literature. We present here a theoretical analysis and a statistical method for tetrasomic linkage analysis with dominant and/or codominant molecular markers. The analysis reveals some essential properties of the tetrasomic model. The method accounts properly for double reduction and incomplete information of marker phenotype in regard to the corresponding phenotype in estimating the coefficients of double reduction and recombination frequency and in testing their significance by using the marker phenotype data. Computer simulation was developed to validate the analysis and the method and a case study with 201 AFLP and SSR markers scored on 228 full-sib individuals of autotetraploid potato is used to illustrate the utility of the method in map construction in autotetraploid species.
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Novel microdeletion in the transforming growth factor β type II receptor gene is associated with giant and large cell variants of nonsmall cell lung carcinoma. Genes Chromosomes Cancer 2006; 46:192-201. [PMID: 17117417 DOI: 10.1002/gcc.20400] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Mutations in the tumor suppressor gene transforming growth factor beta (TGFB) Type II receptor (TGFBR2) are frequently found in many cancers with microsatellite instability, but are less common in lung cancer. In the present study, we looked for mutations in TGFBR2 in nonsmall cell lung carcinoma (NSCLC) cells and tissues. A novel homozygous microdeletion (c.492_507del) was identified in two cell lines derived from the same giant cell carcinoma (GCC) and was confirmed in the corresponding tumor tissues. Furthermore, a heterozygous c.492_507del was found in the germ-line of one patient, as well as in the other GCC cases and some large cell carcinomas (LCC) but not in other subtypes of NSCLC. The 16 bp-microdeletion introduced a premature stop codon at positions 590-592 of the cDNA, resulting in a truncated TGFBR2 protein with a mutated transmembrane domain and loss of kinase domain. The GCC cells were characterized as being unresponsive to TGFB induction both in growth inhibition and stimulation of extracellular matrix protein. Moreover, after the reconstitution of wild-type TGFBR2 expression, the sensitivity to TGFB was restored. Therefore, mutated TGFBR2 seems to play an important role in the abrogation of TGFB signal transduction in GCC cells.
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Abstract
Allozyme and PCR-based molecular markers have been widely used to investigate genetic diversity and population genetic structure in autotetraploid species. However, an empirical but inaccurate approach was often used to infer marker genotype from the pattern and intensity of gel bands. Obviously, this introduces serious errors in prediction of the marker genotypes and severely biases the data analysis. This article developed a theoretical model to characterize genetic segregation of alleles at genetic marker loci in autotetraploid populations and a novel likelihood-based method to estimate the model parameters. The model properly accounts for segregation complexities due to multiple alleles and double reduction at autotetrasomic loci in natural populations, and the method takes appropriate account of incomplete marker phenotype information with respect to genotype due to multiple-dosage allele segregation at marker loci in tetraploids. The theoretical analyses were validated by making use of a computer simulation study and their utility is demonstrated by analyzing microsatellite marker data collected from two populations of sycamore maple (Acer pseudoplatanus L.), an economically important autotetraploid tree species. Numerical analyses based on simulation data indicate that the model parameters can be adequately estimated and double reduction is detected with good power using reasonable sample size.
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Theoretical basis for genetic linkage analysis in autotetraploid species. Proc Natl Acad Sci U S A 2004; 101:7040-5. [PMID: 15100415 PMCID: PMC406462 DOI: 10.1073/pnas.0304482101] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2003] [Accepted: 03/15/2004] [Indexed: 11/18/2022] Open
Abstract
Linkage analysis in autotetraploid species has been an historical challenge in quantitative genetics theory and is a stumbling block that urgently needs to be removed in the rapidly emerging genome research on this species, such as cultivated potato. This article presents theory of a full model of tetrasomic linkage and develops a statistical framework for the linkage analysis. The model considers both double reduction and recombination, the most essential features of tetrasomic inheritance with linked loci, whereas the statistical method takes appropriate account of the major complexities in analyzing both dominant and codominant molecular marker data during map reconstruction in tetraploid species. These complexities include the problems arising from multiple dosage of allelic inheritance, the null allele, allelic segregation distortion, mixed bivalent and quadrivalent pairing in meiosis, and incomplete information of marker phenotype data. The theoretical analysis established the relationship between the coefficients of double reduction at linked loci, which is essential in the present tetrasomic linkage analysis and in assessing the impact of double reduction on the evolution of tetraploid populations. The statistical method, based on the combination of theoretical analysis and a computer-based algorithm, provided analytical tools for predicting the maximum-likelihood estimates of the model parameters. A simulation study showed the feasibility of a practical implementation of the method, detailed the procedure of the analysis, validated the power and reliability in the parameter estimation, and compared the present method with those proposed in the current literature.
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Defective Expression of Transforming Growth Factor β Receptor Type II Is Associated with CpG Methylated Promoter in Primary Non-Small Cell Lung Cancer. Clin Cancer Res 2004; 10:2359-67. [PMID: 15073112 DOI: 10.1158/1078-0432.ccr-0959-3] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE Reduced expression of the transforming growth factor beta receptor type II (TGF beta RII), a key inhibitor of epithelial cell growth and tumor suppressor gene, was reported frequently in many types of tumors including non-small cell lung cancer (NSCLC). This study explored the significance of the TGF beta RII gene in NSCLC carcinogenesis. EXPERIMENTAL DESIGN With 43 independent pairs of tumor and paracarcinoma tissue samples from patients with primary NSCLC, we carried out PCR-denaturing gradient gel electrophoresis screening for DNA variants over the coding sequence of the TGF beta RII gene, immunohistochemical assay of TGF beta RII expression, methylation-specific PCR analysis, and semiquantitative reverse transcription-PCR. RESULTS The PCR-denaturing gradient gel electrophoresis did not detect variation in the whole coding sequence of the TGF beta RII gene, but the immunohistochemistry experiment revealed reduced or lost expression of the gene in 44% (19 of 43) of the tumor samples. The methylation analysis on the 19 pairs detected the frequent occurrence of methylated TGF beta RII promoter in tumor tissues, whereas most of the paracarcinoma tissues were free of methylation. The reduced TGF beta RII expression was highly significantly associated with the methylation event (P < 10(-4)). The reverse transcription-PCR analysis demonstrated a clear agreement between reduced TGF beta RII expression and decreased mRNA level of the gene in the tumor tissue samples. CONCLUSIONS TGF beta RII plays an important role as a tumor suppressor in NSCLC carcinogenesis. The defective expression may serve as one of most important molecular mechanisms in explaining progression of the disease. In particular, aberrant 5' CpG methylation of the gene has explained the down-regulation of the gene at a transcriptional level.
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Mutational analysis of the transforming growth factor beta receptor type I gene in primary non-small cell lung cancer. Lung Cancer 2003; 40:281-7. [PMID: 12781426 DOI: 10.1016/s0169-5002(03)00121-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Transforming growth factor-beta receptor-dependent signals are critical for cell growth and differentiation and are often disrupted during tumorigenesis. The entire coding region of TGFbetaRI and flanking intron sequences from 53 primary non-small cell lung cancer (NSCLC) tissues were examined for alterations using SSCP and direct sequencing. No somatic point mutations other than two silent mutations and a polymorphism were found in the TGFbetaRI gene. The two silent mutations located at codon 344 (AAT to AAC) and codon 406 (TTA to CTA), respectively, and the polymorphism was at the 24th base of intron 7 (G to A). To investigate whether the presence of this polymorphism is associated with NSCLC, we determined its allele distribution in all the 53 carcinomas and 89 normal controls. Interestingly, we found that the subjects with homozygous genotype A/A displayed more than 3-fold increased risk of developing NSCLC than the common wild genotype G/G. As the first report, the present study showed that TGFbetaRI gene is not a frequent site of spontaneous mutational inactivation while the detected polymorphism is frequent in the pathogenesis of NSCLC.
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Factors governing selective formation of specific disulfides in synthetic variants of alpha-conotoxin. Biochemistry 1991; 30:11343-8. [PMID: 1958670 DOI: 10.1021/bi00111a021] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
alpha-Conotoxin GI is a snail toxin protein consisting of 13 amino acids cross-linked by 2 intramolecular disulfide bridges. This toxin is an antagonist of acetylcholine receptors. The native sequence has been synthesized, along with nine additional variants in which non-cysteine residues are replaced by alanine or the cysteine positions are altered. Each reduced peptide has been oxidized by reaction with oxygen or glutathione both in a folding buffer and in 6 M guanidine hydrochloride. Purified products of oxidation have been characterized with respect to molecular weights and the positions of disulfides. The four cysteines in conotoxin can form two intramolecular disulfides in three different combinations. Relative yields of each of the three isomers have been determined, thereby permitting evaluation of the roles of non-cysteine residues and cysteine placements in the folding of conotoxin. Cysteine positions dominate factors directing formation of the nativelike isomer in a manner that may be predicted from equilibrium constants for loop formation in model peptides containing two cysteines. Alanine substitutions at several positions which are conserved in naturally occurring conotoxins affect the discrimination between the two most favored disulfide arrangements. Substitutions at three nonconserved positions have no structural effect on isomer yields. It therefore is possible to vary these latter three positions in a manner which might help to generate a functional binding surface which is complementary to receptors in the specific prey of a particular species of snail, without affecting the toxin's folding.
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Dependence of formation of small disulfide loops in two-cysteine peptides on the number and types of intervening amino acids. J Biol Chem 1989; 264:18472-9. [PMID: 2808384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Microscopic disulfide-exchange rate constants have been measured for the formation and opening of small disulfide loops in reactions between glutathione and peptides containing 2 cysteines. Twelve cysteine-Xm-cysteine peptides have been studied, where X is an amino acid and m is the number of amino acids between the cysteines. Homopolymers of alanine for m equaling 0-5 are evaluated, as well as X1 and X2 series employing glycine, valine, or proline. Equilibrium constants Kc for loop closing are only slightly dependent on the nature of X. Loops with even values of m generally are favored relative to loops with odd values. Kc increases in the rank order X1, X3, X0, X5, X4, and X2. Formation of a disulfide between sequentially adjacent cysteines therefore is not especially difficult. The dependence of Kc on the odd-even nature of m is compared with similar patterns observed both in statistics of disulfide formation in naturally occurring proteins and in theoretical studies of peptide cyclization. The relative equilibrium populations of intramolecular disulfides in peptides containing cysteine-cysteine-cysteine and cysteine-serine-cysteine-serine-cysteine clusters are consistent with predictions based on the values of Kc in the two-cysteine peptides.
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Dependence of formation of small disulfide loops in two-cysteine peptides on the number and types of intervening amino acids. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(18)51490-3] [Citation(s) in RCA: 97] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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[Diagnosis and treatment of old ruptures of lateral ligament of the ankle joint (author's transl)]. ZHONGHUA WAI KE ZA ZHI [CHINESE JOURNAL OF SURGERY] 1981; 19:668-70. [PMID: 7346046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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[Early diagnosis and treatment of rupture of the lateral ligament of the ankle (author's transl)]. ZHONGHUA WAI KE ZA ZHI [CHINESE JOURNAL OF SURGERY] 1980; 18:339-41. [PMID: 6777127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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