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排序方式: 共有771条查询结果,搜索用时 15 毫秒
1.
Francisco Alcaide Enric Brillas Pere-Lluı́s Cabot 《Journal of electroanalytical chemistry (Lausanne, Switzerland)》2004,566(1):235-240
A comparative study of an O2-diffusion cathode and a H2-diffusion anode has been performed to ascertain the limiting processes, when they are combined in a flow alkaline fuel cell with hydroperoxide ion generation. The linear sweep voltammograms and the impedance diagrams of both electrodes show large differences. The cathode reaction is charge transfer-controlled up to current densities of at least 1 A cm?2, whereas the dissociative adsorption, charge transfer and diffusion of H2 appear to limit the anode reaction. The anode, with limiting current densities of about 90 and 150 mA cm?2 for 1.0 and 6.0 M KOH, respectively, then clearly controls the hydroperoxide ion production in the fuel cell. Diffuse reflectance infrared Fourier transform spectroscopy and X-ray photoelectron spectroscopy reveal that, the carbon of the H2-diffusion anode does not undergo significant oxygen functionalisation during hydroperoxide ion generation in the fuel cell. 相似文献
2.
Josep Oriola Cristina Hernandez Rafael Simo Anna Barceló Roser Casamitjana Enric Vilardell & Francisca Rivera-Fillat 《Clinical endocrinology》1996,44(2):207-212
OBJECTIVE Genetic analysis is now essential for the accurate screening of families with multiple endocrine neoplasia type 2 (MEN2). We present the genetic analyses by both haplotype and direct RET proto-oncogene mutation analysis in seven Mediterranean MEN 2A families and have compared these results with biochemical screening tests and pathological examinations.
DESIGN Total DNA was extracted from leucocytes. Linkage analysis was performed using five RFLP systems from three loci that flank the MEN2A locus (FNRB, RBP3, D10S15). RET proto-oncogene analysis was carried out by automatic DNA sequencing and adequate digestion of PCR amplified products for exons 10 and 11. Screening for medullary thyroid carcinoma or C-cell hyperplasia was performed by the pentagastrin provocation test. Adrenal medullary function was assessed by measurements of 24-hour urinary excretion of catecholamines and their metabolites. Serum calcium and phosphate measurements were the initial screen for hyperparathyroidism. Serum PTH was determined only if hyperparathyroidism was suggested by the former determinations.
PATIENT Genetic study was performed in 59 individuals (39 at risk) from seven kindreds of Mediterranean origin with MEN 2A.
RESULTS Diagnosis by linkage analysis was not possible in 30% of individuals at risk, but RET proto-oncogene analysis identified all these individuals. Mutations of the RET proto-oncogene were detected in exon 10 (codon 618) in one MEN 2A kindred and in exon 11 (codon 634) in the others. The results of direct analysis were concordant with linkage studies in each case. Three individuals from different MEN 2A kindreds, who were subsequently shown not to be gene carriers, had false positive pentagastrin stimulation tests.
CONCLUSION Biochemical tests can be replaced by direct DNA mutation analysis as the first line screening test in order to identify gene carriers of MEN 2A. 相似文献
DESIGN Total DNA was extracted from leucocytes. Linkage analysis was performed using five RFLP systems from three loci that flank the MEN2A locus (FNRB, RBP3, D10S15). RET proto-oncogene analysis was carried out by automatic DNA sequencing and adequate digestion of PCR amplified products for exons 10 and 11. Screening for medullary thyroid carcinoma or C-cell hyperplasia was performed by the pentagastrin provocation test. Adrenal medullary function was assessed by measurements of 24-hour urinary excretion of catecholamines and their metabolites. Serum calcium and phosphate measurements were the initial screen for hyperparathyroidism. Serum PTH was determined only if hyperparathyroidism was suggested by the former determinations.
PATIENT Genetic study was performed in 59 individuals (39 at risk) from seven kindreds of Mediterranean origin with MEN 2A.
RESULTS Diagnosis by linkage analysis was not possible in 30% of individuals at risk, but RET proto-oncogene analysis identified all these individuals. Mutations of the RET proto-oncogene were detected in exon 10 (codon 618) in one MEN 2A kindred and in exon 11 (codon 634) in the others. The results of direct analysis were concordant with linkage studies in each case. Three individuals from different MEN 2A kindreds, who were subsequently shown not to be gene carriers, had false positive pentagastrin stimulation tests.
CONCLUSION Biochemical tests can be replaced by direct DNA mutation analysis as the first line screening test in order to identify gene carriers of MEN 2A. 相似文献
3.
Wolfram syndrome (WS) is an autosomal recessive neurodegenerative disorder characterised by early onset diabetes mellitus and progressive optic atrophy, as well as other clinical features such as deafness, diabetes insipida, renal tract abnormalities and diverse psychiatric illnesses. A gene responsible for WS was identified in 4p16.1 (WFS1). It encodes a putative 890 amino acid transmembrane protein expressed in a wide spectrum of tissues. Recently, a new locus for WS has been located on 4q22-24, providing additional evidence for the genetic heterogeneity of this syndrome. We have studied the presence of WFS1 variants in three groups of individuals: patients with diabetes mellitus, patients with deafness and patients with both conditions. A fourth group of healthy subjects was used as control. We have identified a total of 18 nucleotide changes in the WFS1 gene: three mutations and 15 polymorphisms. Six of these changes were previously undescribed. Four of the 15 polymorphisms studied among the patients group present statistical differences in the allelic and genotypic distribution when comparing affected vs control groups. 相似文献
4.
5.
Alonso J Frayle H Menéndez I López A García-Miguel P Abelairas J Sarret E Vendrell MT Navajas A Artigas M Indiano JM Carbone A Torrenteras C Palacios I Pestaña A 《Human mutation》2005,25(1):99
Constitutional mutations in the RB1 gene predispose to retinoblastoma development. Hence genetic screening of retinoblastoma patients and relatives is important for genetic counseling purposes. In addition, RB1 gene mutation studies may help decipher the molecular mechanisms leading to tumors with different degrees of penetrance or expressivity. In the course of genetically screening of 107 hereditary and non-hereditary retinoblastoma patients (11 familiar bilateral, 4 familiar unilateral, 49 sporadic bilateral and 43 sporadic unilateral) and kindred from Spain, Colombia and Cuba, using direct PCR sequencing, we observed 45 distinct mutations and four RB1 deletions in 53 patients (9 familiar bilateral, 2 familiar unilateral, 31 sporadic bilateral and 11 sporadic unilateral). Most of these mutations (26/45, 57%) have not been reported before. In 32 patients, the predisposing mutations correspond to nonsense (mainly CpG transitions) and small insertions or deletions whose expected outcome is a truncated Rb protein that lacks the functional pockets and tail. Five single aminoacid replacements and seventeen mutations affecting splicing sites were also observed in retinoblastoma patients. Two of these sixteen mutations are of unclear pathogenic nature. 相似文献
6.
7.
Variceal ligation plus nadolol compared with ligation for prophylaxis of variceal rebleeding: a multicenter trial 总被引:12,自引:0,他引:12
de la Peña J Brullet E Sanchez-Hernández E Rivero M Vergara M Martin-Lorente JL Garcia Suárez C 《Hepatology (Baltimore, Md.)》2005,41(3):572-578
beta-Blockers and endoscopic variceal ligation (EVL) have proven to be valuable methods in the prevention of variceal rebleeding. The aim of this study was to compare the efficacy of EVL combined with nadolol versus EVL alone as secondary prophylaxis for variceal bleeding. Patients admitted for acute variceal bleeding were treated during emergency endoscopy with EVL or sclerotherapy and received somatostatin for 5 days. At that point, patients were randomized to receive EVL plus nadolol or EVL alone. EVL sessions were repeated every 10 to 12 days until the varices were eradicated. Eighty patients with cirrhosis (alcoholic origin in 66%) were included (Child-Turcotte-Pugh A, 15%; B, 56%; C, 29%). The median follow-up period was 16 months (range, 1-24 months). The variceal bleeding recurrence rate was 14% in the EVL plus nadolol group and 38% in the EVL group (P = .006). Mortality was similar in both groups: five patients (11.6%) died in the combined therapy group and four patients (10.8%) died in the EVL group. There were no significant differences in the number of EVL sessions to eradicate varices: 3.2 +/- 1.3 in the combined therapy group versus 3.5 +/- 1.3 in the EVL alone group. The actuarial probability of variceal recurrence at 1 year was lower in the EVL plus nadolol group (54%) than in the EVL group (77%; P = .06). Adverse effects resulting from nadolol were observed in 11% of the patients. In conclusion, nadolol plus EVL reduces the incidence of variceal rebleeding compared with EVL alone. A combined treatment could lower the probability of variceal recurrence after eradication. 相似文献
8.
Enric Clos Ricard Pruna Matilda Lundblad Rosa Artells Nicola Maffulli 《Medical principles and practice》2021,30(1):92
IntroductionFootball is characterised by intermittent high-intensity efforts varying according to the field position of a player. We aimed to ascertain whether polymorphisms in the ACTN3 gene are associated with different playing positions in elite professional football players.Subjects and MethodsGenotyping of the ACTN3 gene was conducted in 43 elite professional football players of a single team. Playing position was recorded based on the player''s most frequent position.ResultsThe genotype distribution was not significant between positions (p = 0.057), while the allele distribution differed significantly (p = 0.035). Goalkeepers (p = 0.04, p = 0.03), central defenders (p = 0.03, p = 0.01), and central midfielders (p = 0.01, p = 0.00) had a significantly different allele distribution compared with wide midfielders and forward players.ConclusionsGenetic biomarkers may be important when analysing performance capability in elite professional football. Identifying the genetic characteristics of a player to adapt his playing position may lead to orientation of positions based on physical capabilities and tissue quality in young football players, and also to performance enhancement in those who are already playing in professional teams. 相似文献
9.
10.