A blood-borne antigen induces rapid T-B cell contact: a potential mechanism for tolerance induction

Understanding the difference between the development of a productive T‐cell response and tolerance is central to discerning how the immune system functions. Intravenous injection of soluble protein is thought to mimic the presentation of self‐serum and orally introduced antigens. It is generally toleragenic. The current view is that this outcome reflects the failure of ‘immunogenic’ dendritic cells to relocate to the T‐cell zone of the secondary lymphoid tissues. Here, using a peptide/I‐E^k tetramer and antibodies to stain splenic sections, we showed that antigen‐specific T cells were activated in the spleen within hours of injection or feeding of protein. The activated T cells were found to be located at the T–B junction, the bridging zone and the B‐cell area, interacting directly with B cells. In addition, B cells gain the ability to present antigen. Our results suggest a way for T cells to be stimulated by blood‐borne antigen presented by naïve B cells, a potential mechanism of tolerance induction.     

Knowledge and Attitudes About Pre-Exposure Prophylaxis Among Young Adults Experiencing Homelessness in Seven U.S. Cities

Purpose

Evidence suggests that young adults experiencing homelessness (YEH) are at elevated risk of HIV compared to housed youth. Given the limited research on pre-exposure prophylaxis (PrEP) awareness among YEH, this study examined their PrEP knowledge and attitudes.

社会、经济与环境因素对老年健康和死亡的影响——基于中国22省份的抽样调查

基于全国22省市886个县15 973位老人2002—2005年跟踪调查数据,本文应用多水平多元logit模型,对社会、经济和环境因素对老年健康和死亡的影响进行了分析。结果表明,控制了个人层面相关变量后,空气污染显著增加了老人ADL（日常生活自理能力）残障、认知功能差与累计健康亏损指数上升的可能性。降雨量的增加则显著降低了老人ADL残障和认知功能差的风险。极低的气温显著增加了老人ADL残障的风险与死亡风险,而极高的气温显著增加了老人认知功能差和累计健康亏损指数上升的可能性。居住在山区的老人ADL残障风险较低,累计健康亏损指数亦较低。此外,人均GDP、15～64岁人口的劳动参与率以及文盲率对中国老年人的生理健康、心理健康、整体健康水平以及死亡风险有显著的、作用方向不同的影响。最后,得出如下结论：保护自然环境、改善社会经济状况的干预措施将有利于改善老人健康、降低老人死亡风险。     

Selenium-Enriched Agaricus bisporus Mushroom Protects against Increase in Gut Permeability ex vivo and Up-Regulates Glutathione Peroxidase 1 and 2 in Hyperthermally-Induced Oxidative Stress in Rats

Dietary effects of organic Se supplementation in the form of Se-enriched Agaricus bisporus mushroom on ileal mucosal permeability and antioxidant selenoenzymes status in heat induced oxidative stress in rats were evaluated. Acute heat stress (40 °C, 21% relative humidity, 90 min exposure) increased ileum baseline short circuit current (Isc; 2.40-fold) and epithelial conductance (Ge; 2.74-fold). Dietary supplementation with Se-enriched A. bisporus (1 µg Se/g feed) reduced (p < 0.05) ileum Isc and Ge during heat stress to 1.74 and 1.91 fold, respectively, indicating protection from heat stress-induced mucosal permeability increase. The expression of ileum glutathione peroxidase (GPx-) 1 and 2 mRNAs were up-regulated (p < 0.05) by 1.90 and 1.87-fold, respectively, for non-heat stress rats on the Se-enriched diet relative to the control. The interplay between heat stress and dietary Se is complex. For rats on the control diet, heat stress alone increased ileum expression of GPx-1 (2.33-fold) and GPx-2 (2.23-fold) relative to thermoneutral conditions. For rats on the Se-enriched diet, heat stress increased (p < 0.05) GPx-1 expression only. Rats on Se-enriched + α-tocopherol diet exhibited increased expression of both genes (p < 0.05). Thus, dietary Se-enriched A. bisporus protected against increase in ileum permeability and up-regulated GPx-1 and GPx-2 expression, selenoenzymes relevant to mitigating oxidative stress.     

Overlap syndrome of autoimmune chronic liver diseases: MRI findings

Purpose:

To describe the MR findings of overlap syndromes of autoimmune chronic liver diseases.

Methods:

Review of clinical and radiological databases between March 2001 and July 2008 for patients with a clinical diagnosis and liver biopsy features compatible with overlap syndrome who had also undergone an abdominal MRI yielded 15 adult patients. MR features of overlap syndrome were reviewed by two radiologists by consensus. Two radiologists independently reviewed the studies in a blinded fashion for primary sclerosing cholangitis (PSC)‐type or non‐PSC‐type features to assess interobserver agreement.

Results:

PSC‐type and non‐PSC‐type overlap syndrome had distinctive MR features. In the consensus review, all 12 patients with PSC‐type overlap syndrome were correctly identified. Imaging findings included central macroregeneration (N = 9), peripheral atrophy (N = 7), biliary duct beading (N = 12), biliary dilation (N = 10), or a combination of all four findings (N = 7). The presence of any of the first three features had 100% specificity for a PSC‐type overlap syndrome. Patients with non‐PSC‐type overlap (N = 3) showed relatively normal liver morphology (N = 3) and minimal biliary ductal dilatation in one patient. There was good interobserver agreement (kappa = 0.76).

Conclusion:

Patients with serologic or pathologic evidence of AIH or PBC with imaging features of PSC may have PSC‐type overlap syndrome. J. Magn. Reson. Imaging 2010; 31: 383–389. © 2010 Wiley‐Liss, Inc.     

Prevalence of cryptosporidiosis in Dammam and Alkhobar, Saudi Arabia

This report presents results from a 6-month study over the period 16 November 1986 to 15 May 1987 which was designed to investigate the prevalence of cryptosporidiosis in Dammam and Alkhobar, Saudi Arabia. A total of 209 stool specimens from children and 112 from adults with diarrhoea were examined. Only two (1%) of the children, both aged 2 years, were positive for Cryptosporidium spp. Giardia lamblia was found in 13 (4%) cases and was found to be the most common protozoan parasite, whereas Salmonella spp. was seen in 19 (6%) cases. Stool specimens were examined for rotavirus from children under 2 years of age; 31 (41%) of the specimens were positive.     

Competing risk of household expansion or institutionalization in late life

OBJECTIVES: The purpose of this study was to evaluate predictors of change in household size and institutionalization in late life. METHODS: The Duke Established Populations for Epidemiologic Studies of the Elderly cohort (n = 3730) was assessed annually (1986-1996). Independent variables included home ownership, income, cognitive and functional ability, chronic illness, mood, household size, social support, and stressful life events. Competing risk of household expansion or institutionalization was modeled using (a) hazard of either event and (b) odds of household expansion or institutionalization among elders who experienced an event. RESULTS: Hazard of either event was associated with younger age, Black race, lower income, cognitive problems and stability, functional abilities and deterioration, low chronic illness burden, being unmarried, having more living children, and recent life events. Among those who reported either event, odds of institutionalization (vs. household expansion) were associated with older age, White race, cognitive and functional problems, high chronic illness burden, being married, having fewer living children, smaller household size, social isolation, and exits of nonspouse coresidents. DISCUSSION: Modeling separate effects of whether there was a household expansion or institutionalization, and if so, which type of event occurred, and taking into account acute and evolving states, enabled more precise understanding of the complex mechanisms involved in determining continued community residence or institutionalization.