842 resultados para Sima, Guang, 1019-1086.
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Although gene by environment interactions may play a key role in the maintenance of genetic polymorphisms, little is known about the ecological factors involved in these interactions. We investigated whether food supply and parasites can mediate covariation between the degree of adult pheomelanin-based coloration, a heritable trait, and offspring body mass in the tawny owl (Strix aluco). We swapped clutches between nests to allocate genotypes randomly among environments. Three weeks after hatching, we challenged the immune system of 80 unrelated nestlings with either a phytohemagglutinin (PHA) or a lipopolysaccharide, surrogates of alternative parasites, and then fed them ad lib. or food-restricted them during the following 6 days in the laboratory. Whatever the immune challenge, nestlings fed ad lib. converted food more efficiently into body mass when their biological mother was dark pheomelanic. In contrast, food-restricted nestlings challenged with PHA lost less body mass when their biological mother was pale pheomelanic. Nestling tawny owls born from differently melanic mothers thus show differing reaction norms relative to food availability and parasitism. This suggests that dark and pale pheomelanic owls reflect alternative adaptations to food availability and parasites, factors known to vary in space and time.
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Abstract The maintenance of genetic variation is a long-standing issue because the adaptive value of life-history strategies associated with each genetic variant is usually unknown. However, evidence for the coexistence of alternative evolutionary fixed strategies at the population level remains scarce. Because in the tawny owl (Strix aluco) heritable melanin-based coloration shows different physiological and behavioral norms of reaction, we investigated whether coloration is associated with investment in maintenance and reproduction. Light melanic owls had lower adult survival compared to dark melanic conspecifics, and color variation was related to the trade-off between offspring number and quality. When we experimentally enlarged brood size, light melanic males produced more fledglings but in poorer condition, and they were less often recruited in the local breeding population than those of darker melanic conspecifics. Our results also suggest that dark melanic males allocate a constant effort to raise their brood independently of environmental conditions, whereas lighter melanic males finely adjust reproductive effort in relation to changes in environmental conditions. Color traits can therefore be associated with life-history strategies, and stochastic environmental perturbation can temporarily favor one phenotype over others. The existence of fixed strategies implies that some phenotypes can sometimes display a "maladapted" strategy. Long-term population monitoring is therefore vital for a full understanding of how different genotypes deal with trade-offs.
Charles Bally et Gustav Shpet en conversation intellectuelle: reconstruire les archives de l'époque.
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English summary: Idea of appeal and the credibility of testimony in the Court of Appeal (s. 1085-1086)
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BACKGROUND: Variables influencing serum hepatitis C virus (HCV) RNA levels and genotype distribution in individuals with human immunodeficiency virus (HIV) infection are not well known, nor are factors determining spontaneous clearance after exposure to HCV in this population. METHODS: All HCV antibody (Ab)-positive patients with HIV infection in the EuroSIDA cohort who had stored samples were tested for serum HCV RNA, and HCV genotyping was done for subjects with viremia. Logistic regression was used to identify variables associated with spontaneous HCV clearance and HCV genotype 1. RESULTS: Of 1940 HCV Ab-positive patients, 1496 (77%) were serum HCV RNA positive. Injection drug users (IDUs) were less likely to have spontaneously cleared HCV than were homosexual men (20% vs. 39%; adjusted odds ratio [aOR], 0.36 [95% confidence interval {CI}, 0.24-0.53]), whereas patients positive for hepatitis B surface antigen (HBsAg) were more likely to have spontaneously cleared HCV than were those negative for HBsAg (43% vs. 21%; aOR, 2.91 [95% CI, 1.94-4.38]). Of patients with HCV viremia, 786 (53%) carried HCV genotype 1, and 53 (4%), 440 (29%), and 217 (15%) carried HCV genotype 2, 3, and 4, respectively. A greater HCV RNA level was associated with a greater chance of being infected with HCV genotype 1 (aOR, 1.60 per 1 log higher [95% CI, 1.36-1.88]). CONCLUSIONS: More than three-quarters of the HIV- and HCV Ab-positive patients in EuroSIDA showed active HCV replication. Viremia was more frequent in IDUs and, conversely, was less common in HBsAg-positive patients. Of the patients with HCV viremia analyzed, 53% were found to carry HCV genotype 1, and this genotype was associated with greater serum HCV RNA levels.
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BACKGROUND: We investigated the incidence and outcome of progressive multifocal leukoencephalopathy (PML) in human immunodeficiency virus (HIV)-infected individuals before and after the introduction of combination antiretroviral therapy (cART) in 1996. METHODS: From 1988 through 2007, 226 cases of PML were reported to the Swiss HIV Cohort Study. By chart review, we confirmed 186 cases and recorded all-cause and PML-attributable mortality. For the survival analysis, 25 patients with postmortem diagnosis and 2 without CD4+ T cell counts were excluded, leaving a total of 159 patients (89 before 1996 and 70 during 1996-2007). RESULTS: The incidence rate of PML decreased from 0.24 cases per 100 patient-years (PY; 95% confidence interval [CI], 0.20-0.29 cases per 100 PY) before 1996 to 0.06 cases per 100 PY (95% CI, 0.04-0.10 cases per 100 PY) from 1996 onward. Patients who received a diagnosis before 1996 had a higher frequency of prior acquired immunodeficiency syndrome-defining conditions (P = .007) but similar CD4+ T cell counts (60 vs. 71 cells/microL; P = .25), compared with patients who received a diagnosis during 1996 or thereafter. The median time to PML-attributable death was 71 days (interquartile range, 44-140 days), compared with 90 days (interquartile range, 54-313 days) for all-cause mortality. The PML-attributable 1-year mortality rate decreased from 82.3 cases per 100 PY (95% CI, 58.8-115.1 cases per 100 PY) during the pre-cART era to 37.6 cases per 100 PY (95% CI, 23.4.-60.5 cases per 100 PY) during the cART era. In multivariate models, cART was the only factor associated with lower PML-attributable mortality (hazard ratio, 0.18; 95% CI, 0.07-0.50; P < .001), whereas all-cause mortality was associated with baseline CD4+ T cell count (hazard ratio per increase of 100 cells/microL, 0.52; 95% CI, 0.32-0.85; P = .010) and cART use (hazard ratio, 0.37; 95% CI, 0.19-0.75; P = .006). CONCLUSIONS: cART reduced the incidence and PML-attributable 1-year mortality, regardless of baseline CD4+ T cell count, whereas overall mortality was dependent on cART use and baseline CD4+ T cell count.
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Down syndrome (DS) is characterized by extensive phenotypic variability, with most traits occurring in only a fraction of affected individuals. Substantial gene-expression variation is present among unaffected individuals, and this variation has a strong genetic component. Since DS is caused by genomic-dosage imbalance, we hypothesize that gene-expression variation of human chromosome 21 (HSA21) genes in individuals with DS has an impact on the phenotypic variability among affected individuals. We studied gene-expression variation in 14 lymphoblastoid and 17 fibroblast cell lines from individuals with DS and an equal number of controls. Gene expression was assayed using quantitative real-time polymerase chain reaction on 100 and 106 HSA21 genes and 23 and 26 non-HSA21 genes in lymphoblastoid and fibroblast cell lines, respectively. Surprisingly, only 39% and 62% of HSA21 genes in lymphoblastoid and fibroblast cells, respectively, showed a statistically significant difference between DS and normal samples, although the average up-regulation of HSA21 genes was close to the expected 1.5-fold in both cell types. Gene-expression variation in DS and normal samples was evaluated using the Kolmogorov-Smirnov test. According to the degree of overlap in expression levels, we classified all genes into 3 groups: (A) nonoverlapping, (B) partially overlapping, and (C) extensively overlapping expression distributions between normal and DS samples. We hypothesize that, in each cell type, group A genes are the most dosage sensitive and are most likely involved in the constant DS traits, group B genes might be involved in variable DS traits, and group C genes are not dosage sensitive and are least likely to participate in DS pathological phenotypes. This study provides the first extensive data set on HSA21 gene-expression variation in DS and underscores its role in modulating the outcome of gene-dosage imbalance.
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Staphylococcus aureus is one of the most common causative pathogens of bloodstream infections (BSIs). In approximately one-half of patients with S. aureus BSI, no portal of entry can be documented. This group of patients has a high risk of developing septic metastases. Similarly, patient populations at high risk of S. aureus BSI and BSI-associated complications include patients receiving hemodialysis, injection drug users, patients with diabetes, and patients with preexisting cardiac conditions or other comorbidities. One of the most severe complications of S. aureus BSI is infective endocarditis, and S. aureus is now the most common cause of infective endocarditis in the developed world. Patients with methicillin-resistant S. aureus BSI or infective endocarditis have higher rates of mortality, compared with patients with methicillin-susceptible S. aureus infection. Nasal carriage is the most important source of S. aureus BSI. Better eradication and control strategies, including nasal decolonization and more-active antibiotics, are needed to combat S. aureus BSIs.
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Von seltenen Erkrankungen, die definitionsgemässeine Prävalenz von unter 1/2000 aufweisen, sindschätzungsweise 5 bis 6 % der Bevölkerung betroffen,d. h. in der Schweiz rund 500 000 Menschen.Eine breit angelegte Umfrage hat erstmals dieSchwierigkeiten und Bedürfnisse der betroffenenPatientinnen und Patienten genau erfasst und aufgezeigt,dass diese Menschen nicht optimal versorgtwerden. In den meisten europäischen Ländernbestehen bereits nationale Pläne für seltene Erkrankungenoder werden in den nächsten Jahren entwickelt.Die Schweiz weist in diesem Bereich einenRückstand von mehreren Jahren auf, der jedoch aufgeholtwerden könnte, falls die kürzlich eingeleitetenInitiativen breite Unterstützung erhalten. BeiOrphan-Medikamenten, die für eine kleine Zahl vonPatientinnen und Patienten bestimmt, aber oft sehrteuer sind, kann das Einzelinteresse dem Allgemeininteresseentgegenstehen. Die seltenen Erkrankungenund ihre Behandlung werfen ethische, gesellschaftliche,ökonomische, aber auch wissenschaftlicheund klinische Fragen auf und zeigen die Grenzendes Wissens und der Mittel auf. Sie sind ein Problemfür das Gesundheitswesen, und eine Herausforderung,der sich die Schweiz stellen sollte.
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Human immunodeficiency virus (HIV)-infected men who have sex with men (MSM) were enrolled in an anorectal Chlamydia trachomatis screening study. Anorectal Chlamydia DNA was detected in 16 (10.9%) of 147 men, mainly among asymptomatic patients and patients having >20 sexual partners. These results support routine anorectal Chlamydia screening in HIV-infected MSM who report unprotected anal intercourse.
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Définies par une prévalence inférieure à 1⁄2000, lesmaladies rares toucheraient 5 à 6 % de la population,soit environ 500 000 personnes en Suisse. Une vasteenquête européenne a révélé pour la première foisavec précision les difficultés et les besoins despatients atteints, et montré que leur prise en chargen'est pas optimale. Des plans nationaux pour lesmaladies rares ont été développés ou vont l'être aucours de prochaines années dans la plupart des payseuropéens. La Suisse a un retard de plusieurs annéesdans ce domaine, mais des initiatives récentespourraient permettre de le combler si elles sontlargement soutenues. Les médicaments orphelins,destinés à un petit nombre de patients mais souventextrêmement coûteux, sont une source potentiellede tensions entre intérêt individuel et intérêt collectif.Entité éthique, sociale, économique, mais aussiscientifique et clinique, les maladies rares et leurstraitements confrontent aux limites des connaissanceset des ressources. Elles constituent un enjeu de santépublique et un défi que la Suisse est invitée à relever.