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Prevailing Hypothesis (prevailing + hypothesis)
Selected AbstractsDental trait anxiety and pain sensitivity as predictors of expected and experienced pain in stressful dental proceduresEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 6 2004Ulrich Klages A prevailing hypothesis suggests that exaggerated pain expectations in dentally anxious and pain-sensitive patients might usually be disconfirmed by a lower level of pain experienced during treatment. The present study was conducted to investigate whether this contention also holds during stressful dental procedures. Patients reporting high and low levels of dental fear and of pain sensitivity were compared in their expected and experienced pain and in the concordance between the two measures. Participants were 97 patients undergoing extraction and root canal treatment. The measuring instruments used were the Dental Anxiety Scale (DAS), the Pain Sensitivity Index (PSI), affective and sensory pain descriptor scales, and a numerical pain-intensity scale. The results demonstrated that patients, in general, expected more pain than they subsequently experienced. Subjects with a high DAS score both expected and experienced more pain than those with a low DAS score. Within the group of subjects with a high DAS score, those indicating high pain sensitivity expected and experienced more pain than their counterparts; additionally, only those reporting low pain sensitivity disconfirmed their high pain expectancies. The results suggest that during stressful dental procedures, patients indicating dental anxiety and pain sensitivity above median levels are especially at risk of stabilizing exaggerated pain expectations and dental fear. [source] Human Heart Cytosolic Reductases and Anthracycline CardiotoxicityIUBMB LIFE, Issue 1 2001Alvaro Mordente Abstract Anthracyclines are a class of antitumor drugs widely used for the treatment of a variety of malignancy, including leukemias, lymphomas, sarcomas, and carcinomas. Different mechanisms have been proposed for anthracycline antitumor effects including freeradical generation, DNA intercalation/binding, activation of signaling pathways, inhibition of topoisomerase II and apoptosis. A life-threatening form of cardiomyopathy hampers the clinical use of anthracyclines. According to the prevailing hypothesis, anthracyclines injure the heart by generating damaging free radicals through iron-catalyzed redox cycling. Although the "iron and freeradical hypothesis" can explain some aspects of anthracycline acute toxicity, it is nonetheless disappointing when referred to chronic cardiomyopathy. An alternative hypothesis implicates C-13 alcohol metabolites of anthracyclines as mediators of myocardial contractile dysfunction ("metabolite hypothesis"). Hydroxy metabolites are formed upon two-electron reduction of the C-13 carbonyl group in the side chain of anthracyclines by cytosolic NADPH-dependent reductases. Anthracycline alcohol metabolites can affect myocardial energy metabolism, ionic gradients, and Ca 2+ movements, ultimately impairing cardiac contraction and relaxation. In addition, alcohol metabolites can impair cardiac intracellular iron handling and homeostasis, by delocalizing iron from the [4Fe-4S] cluster of cytoplasmic aconitase. Chronic cardiotoxicity induced by C-13 alcohol metabolite might be primed by oxidative stress generated by anthracycline redox cycling ("unifying hypothesis"). Putative cardioprotective strategies should be aimed at decreasing C-13 alcohol metabolite production by means of efficient inhibitors of anthracycline reductases, as short-chain coenzyme Q analogs and chalcones that compete with anthracyclines for the enzyme active site, or by developing novel anthracyclines less susceptible to reductive metabolism. [source] Nuclear and chloroplast microsatellites reveal extreme population differentiation and limited gene flow in the Aegean endemic Brassica cretica (Brassicaceae)MOLECULAR ECOLOGY, Issue 23 2007KRISTINA EDH Abstract Nuclear and chloroplast microsatellite markers were used to study population structure and gene flow among seven Cretan populations of the Aegean endemic plant species Brassica cretica (Brassicaceae). Both nuclear and chloroplast markers revealed exceptionally high levels of population differentiation (overall FST = 0.628 and 1.000, respectively) and relatively little within-population diversity (overall HS = 0.211 and 0.000, respectively). Maximum-likelihood estimates of directional migration rates were low among all pairs of populations (average Nm = 0.286). There was no evidence that differences in flower colour between populations had any influence on historical levels of gene flow. In addition, a haplotype network showed that all five chloroplast haplotypes found in the sample were closely related. Together, these results suggest that current patterns of diversification in B. cretica are mainly a result of genetic drift during the last half million years. The main conclusions from the present study are consistent with the prevailing hypothesis that plant diversification in the Aegean region is driven by random rather than adaptive differentiation among isolated populations. [source] An evolution revolution provides further revelationBIOESSAYS, Issue 12 2007James R. Lupski The extent of copy-number variation (CNV) in the human genome has been appreciated only recently. Nevertheless, for almost four decades, gene duplication has been a prevailing hypothesis for evolutionary change. Recently, gene CNV spanning 60 million years of human and primate evolution has been determined1 enabling lineage-specific gene CNV to be identified. Primate lineage-specific gene CNV studies reveal that almost one third of all human genes exhibit a copy-number change in one or more primate species. Intriguingly, human lineage-specific gene amplification can be correlated to the emergence of human-specific traits such as cognition and endurance running. © 2007 Wiley Periodicals, Inc. BioEssays 29:1182,1184, 2007. © 2007 Wiley Periodicals, Inc. [source] Selected gene polymorphisms and their interaction with maternal smoking, as risk factors for gastroschisis,,BIRTH DEFECTS RESEARCH, Issue 10 2006Claudine P. Torfs Abstract BACKGROUND: Gastroschisis is a severe birth defect in which the infant is born with a portion of the intestines extruding through a small tear in the abdominal wall, usually to the right of the umbilical cord. Its etiology is unknown, but the prevailing hypothesis is that it results from a vascular accident at the time of involution of the right umbilical vein or of the development of the superior mesenteric artery. METHODS: In a case-control study of 57 cases of gastroschisis and 506 controls, we tested DNA for polymorphisms of 32 genes representing enzymes involved in angiogenesis, blood vessel integrity, inflammation, wound repair, and dermal or epidermal strength. RESULTS: In logistic regression, controlling for maternal ethnicity, and using the homozygote wild-type as referent, the following gene polymorphisms were associated with an increased risk for a gastroschisis for heterozygotes: ICAM1 gly241arg (odds ratio [OR], 1.9; 95% confidence interval [CI], 1.1 ,3.4); NOS3 glu298asp (OR, 1.9; 95% CI, 1.1,3.4); NPPA 2238T > C (OR, 1.9; 95% CI, 1.0,3.4); and ADD1 gly460trp (OR, 1.5; 95% CI, 0.8,2.8). Additionally, for the NPPA and ADD1 single-nucleotide polymorphisms (SNPs), the homozygote variants had a significantly higher risk than the heterozygotes (OR, 7.5; 95% CI, 1.7,33.5 and OR, 4.9; 95% CI, 1.9,12.9, respectively). Three SNPs showed a strong interaction with maternal smoking. The risk for smokers with 1 or 2 variant alleles compared to nonsmokers with the wild-type allele were: NOS3 (OR, 5.2; 95% CI, 2.4,11.4); ICAM1 (OR, 5.2; 95% CI, 2.1,12.7); and NPPA (OR, 6.4; 95% CI, 2.8,14.6). CONCLUSIONS: These results support the hypothesis of a vascular compromise as part of a multifactorial etiology of gastroschisis involving both genes and environmental factors. Birth Defects Research (Part A) 76:723,730, 2006. © 2006 Wiley-Liss, Inc. [source] | ||||||||||