992 resultados para Etiology.


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Includes an updated version (July 1970) of the Special Virus Cancer Program progress report no. 7, originally issued in May 1970.

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Bibliography: leaves 27-30.

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Literature: p. 1-63.

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The negative effects of very low birthweight on intellectual development have been well documented, and more recently this effect has been shown to generalise to birthweights within the normal range. In this study we investigate the etiology of this relationship by using a classical twin design to disentangle the contributions of genes and environment. A previous Dutch study (Boomsma et al., 2001) examining these effects indicated that genes were important in mediating the association of birthweight to full IQ measured at ages 7 and 10, but not at ages 5 and 12. Here the association between birthweight and IQ at age 16 is considered (N = 523 twin pairs). Using variance components modeling we found that the genetic variance in birthweight (4%) completely overlapped with that in verbal IQ but not performance or full IQ. Results further showed the importance of shared environmental effects on birthweight (similar to 60%) but not on IQ (with genes explaining up to 72% of IQ variance). Models incorporating a direction of causation parameter between birthweight and IQ provided adequate fit to the data in either causal direction for performance and full IQ, but the model with verbal 10 causing birthweight was preferred to one in which birthweight influenced verbal IQ. As the measurement of birthweight precedes the measurement of twins' IQ at age 16, the influence of verbal IQ might be better considered as a proxy for parents' 10 or education, and it is possible that brighter mothers provide better prenatal environments for their children.

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Research into the etiology of social phobia has lagged far behind that of descriptive and maintaining factors. The current paper reviews data from a variety of sources that have some bearing on questions of the origins of social fears. Areas examined include genetic factors, temperament, childrearing, negative life events, and adverse social experiences. Epidemiological data are examined in detail and factors associated with social phobia such as cognitive distortions and social skills are also covered. The paper concludes with an initial model that draws together some of the current findings and aims to provide a platform for future research directions. (C) 2004 Elsevier Ltd. All rights reserved.

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The incidence of preeclampsia is reduced by a third in smokers, but not in snuff users. Soluble Flt-1 (sFlt-1) and soluble endoglin (sEng) are increased prior to the clinical onset of preeclampsia. Animals exposed to high circulating levels of sFlt-1 and sEng elicit severe preeclampsia-like symptoms. Smokers have reduced circulating sFlt-1 and cigarette smoke extract decreases sFlt-1 release from placental villous explants. An anti-inflammatory enzyme, heme oxygenase-1 (HO-1) and its metabolite carbon monoxide (CO), inhibit sFlt-1 and sEng release. Women with preeclampsia exhale less CO than women with normal pregnancies and HO expression decreases as the severity of preeclampsia increases. In contrast, sFlt-1 levels increase with increasing severity. More importantly, chorionic villous sampling from women at eleven weeks gestation shows that HO-1 mRNA expression is decreased in women who go on to develop preeclampsia. Collectively, these facts provide compelling evidence to support the proposition that the pathogenesis of preeclampsia is largely due to loss of HO activity. This results in an increase in inflammation and excessive elevation of the two key anti-angiogenic factors responsible for the clinical signs of preeclampsia. These findings provide strong evidence for a protective role of HO-1 in pregnancy and identify HO as a target for the treatment of preeclampsia. The cardiovascular drugs, statins, stimulate HO-1 expression and inhibit sFlt-1 release in vivo and in vitro, thus, they have the potential to ameliorate early onset preeclampsia. The StAmP trial is underway to address this and if positive, its outcome will lead to the very first therapeutic intervention to prolong affected pregnancies.

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Acute respiratory infections caused by bacterial or viral pathogens are among the most common reasons for seeking medical care. Despite improvements in pathogen-based diagnostics, most patients receive inappropriate antibiotics. Host response biomarkers offer an alternative diagnostic approach to direct antimicrobial use. This observational cohort study determined whether host gene expression patterns discriminate noninfectious from infectious illness and bacterial from viral causes of acute respiratory infection in the acute care setting. Peripheral whole blood gene expression from 273 subjects with community-onset acute respiratory infection (ARI) or noninfectious illness, as well as 44 healthy controls, was measured using microarrays. Sparse logistic regression was used to develop classifiers for bacterial ARI (71 probes), viral ARI (33 probes), or a noninfectious cause of illness (26 probes). Overall accuracy was 87% (238 of 273 concordant with clinical adjudication), which was more accurate than procalcitonin (78%, P < 0.03) and three published classifiers of bacterial versus viral infection (78 to 83%). The classifiers developed here externally validated in five publicly available data sets (AUC, 0.90 to 0.99). A sixth publicly available data set included 25 patients with co-identification of bacterial and viral pathogens. Applying the ARI classifiers defined four distinct groups: a host response to bacterial ARI, viral ARI, coinfection, and neither a bacterial nor a viral response. These findings create an opportunity to develop and use host gene expression classifiers as diagnostic platforms to combat inappropriate antibiotic use and emerging antibiotic resistance.

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Progressive multifocal leukoencephalopathy (PML) caused by reactivation of the JC virus (JCV), a human polyomavirus, occurs in autoimmune disorders, most frequently in systemic lupus erythematosus (SLE). We describe a HIV-negative 34-year-old female with SLE who had been treated with immunosuppressant therapy (IST; steroids and azathioprine) since 2004. In 2011, she developed decreased sensation and weakness of the right hand, followed by vertigo and gait instability. The diagnosis of PML was made on the basis of brain MRI findings (posterior fossa lesions) and JCV isolation from the cerebrospinal fluid (700 copies/ml). IST was immediately discontinued. Cidofovir, mirtazapine, mefloquine and cycles of cytarabine were sequentially added, but there was progressive deterioration with a fatal outcome 1 year after disease onset. This report discusses current therapeutic choices for PML and the importance of early infection screening when SLE patients present with neurological symptoms. In the light of recent reports of PML in SLE patients treated with rituximab or belimumab, we highlight that other IST may just as well be implicated. We conclude that severe lymphopenia was most likely responsible for JCV reactivation in this patient and discuss how effective management of lymphopenia in SLE and PML therapy remains an unmet need.

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Background: Chronic kidney disease (CKD) patients often have gastrointestinal symptoms which may result in malnutrition and a negative impact on their quality of life. Modulation of the gut microbiota can be a strategy to promote host health and homeostasis. Case report: The authors present a case of chronic diarrhea in a hemodialysis (HD) patient with an unknown etiology. After about one year and several failed interventions, synbiotic therapy was performed. The diarrhea episodes ceased after three months of daily supplementation and both biochemical and nutritional parameters improved. Synbyotic therapy promoted clinical benefits in this patient. Discussion: Therefore, this simple therapy may be a promising alternative in CKD and it should be tested in larger studies.

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The interpretative framework presented here provides a rationale for many well-known features of cardiovascular diseases. Prolonged acidemia with high blood levels of free fatty acids is proposed to shape the basic context for formation of fatty acid micelles and vesicles with an acidic core that fuse with the endothelia, disrupt vital cell processes, and initiate atherosclerotic plaque formation. It offers an explanation for the distributed localization of atherosclerotic lesions, and how mild cases of occurrence of fatty acids vesicles formed within the heart and the arteries close to the heart may cause such lesions. It provides a rationale for how acute events, namely heart attacks and strokes, may arise from stormy development of fatty acid vesicles within the heart. Additionally, a process is proposed for clot development from the existing fatty acid vesicles.

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Primary Myelofibrosis (PMF) is the end-stage of Philadelphia-negative myeloproliferative neoplasms (MPN) and is characterized by fibrosis and hematopoietic failure in bone marrow, with a consequential migration of the malignant hematopoietic stem cells (HSC) in the spleen where they induce ineffective haematopoiesis. To date, available therapies for PMF are still palliative and do not halt the progression of this neoplasm. During my PhD years, our laboratory investigated the factors promoting the onset and progression of PMF. In our PMF mice model, Gata1low mouse, we studied the role of the interaction of HSC niche with megakaryocytes and HSC localization in the bone marrow during their division and cycle. We observed the inflammation and the main protagonists (LNC-2, CXCL1, and TGF-β) of this process and how their level changes before and after the onset of the disease. We investigated the different megakaryocyte populations in the fibrotic environment in different organs (lung and bone marrow) to define the megakaryocytes implicated in this process. In human samples, we described different ultrastructural abnormalities of megakaryocytes from the bone marrow and the spleen, identifying a possible different metabolism in those two populations. In conclusion, we highlighted the intricated crosstalk between the megakaryocytes, the niche and HSC in PMF. We identified megakaryocytes-dependent cytokines altering the homeostasis of the niche and HSC. Those cytokines could be used as alternative therapeutic targets. Furthermore, we observed different megakaryocytic populations in different organs, providing new prospective on the role of megakaryocytes in different microenvironments.