Rapid hepatic metabolism of 7-ketocholesterol in vivo: implications for dietary oxysterols.

7-Ketocholesterol is a major dietary oxysterol and the predominant non-enzymically formed oxysterol in human atherosclerotic plaque. We tested the hypothesis that 7-ketocholesterol is preferentially retained by tissues relative to cholesterol in vivo. To ensure rapid tissue uptake, acetylated low density lipoprotein, labeled with esters of [(14)C]-7-ketocholesterol and [(3)H]cholesterol, was injected into rats via a jugular catheter. At timed intervals (2 min to 24 h) rats (n = 48 total) were exsanguinated and tissues were dissected and assayed for radioactivity. In two experiments the majority of both radiolabels appeared in the liver after 2 min. In all tissues, (14)C appeared transiently and did not accumulate. Rather, it was metabolized in the liver and excreted into the intestine mainly as aqueous-soluble metabolites (presumably bile acids). By 9 h, (14)C in the liver had decreased to 10% of the injected dose while 36% was present in the intestine. In contrast, at 9 h 38% of (3)H was evident in the liver while only 5% was found in the intestine. Unlike [(3)H]cholesterol, little (14)C was found to re-enter the circulation, indicating that enterohepatic recycling of 7-ketocholesterol was negligible.This is the first report of the distribution of an oxysterol relative to cholesterol, administered simultaneously, in a whole animal model. The finding that [(14)C]-7-ketocholesterol is rapidly metabolized and excreted by the liver suggests that diet may not be a major source of oxysterols in atherosclerotic plaque, and that perhaps dietary oxysterols make little or no contribution to atherogenesis.     

Global assessment of existing HIV and key population stigma indicators: A data mapping exercise to inform country-level stigma measurement

BackgroundStigma is an established barrier to the provision and uptake of HIV prevention, diagnostic, and treatment services. Despite consensus on the importance of addressing stigma, there are currently no country-level summary measures to characterize stigma and track progress in reducing stigma around the globe. This data mapping exercise aimed to assess the potential for existing data to be used to summarize and track stigma, including discrimination, related to HIV status, or key population membership at the country level.Methods and findingsThis study assessed existing indicators of stigma related to living with HIV or belonging to 1 of 4 key populations including gay men and other men who have sex with men, sex workers, people who use drugs, and transgender persons. UNAIDS Strategic Information Department led an initial drafting of possible domains, subdomains, and indicators, and a 3-week e-consultation was held to provide feedback. From the e-consultation, 44 indicators were proposed for HIV stigma; 14 for sexual minority stigma (including sexual behavior or orientation) related to men who have sex with men; 12 for sex work stigma; 10 for drug use stigma; and 17 for gender identity stigma related to transgender persons. We conducted a global data mapping exercise to identify and describe the availability and quality of stigma data across countries with the following sources: UNAIDS National Commitments and Policies Instrument (NCPI) database; Multiple Indicator Cluster Surveys (MICS); Demographic and Health Surveys (DHS); People Living with HIV Stigma Index surveys; HIV Key Populations Data Repository; Integrated Biological and Behavioral Surveys (IBBS); and network databases. Data extraction was conducted between August and November 2020. Indicators were evaluated based on the following: if an existing data source could be identified; the number of countries for which data were available for the indicator at present and in the future; variation in the indicator across countries; and considerations of data quality or accuracy. This mapping exercise resulted in the identification of 24 HIV stigma indicators and 10 key population indicators as having potential to be used at present in the creation of valid summary measures of stigma at the country level. These indicators may allow assessment of legal, societal, and behavioral manifestations of stigma across population groups and settings. Study limitations include potential selection bias due to available data sources to the research team and other biases due to the exploratory nature of this data mapping process.ConclusionsBased on the current state of data available, several indicators have the potential to characterize the level and nature of stigma affecting people living with HIV and key populations across countries and across time. This exercise revealed challenges for an empirical process reliant on existing data to determine how to weight and best combine indicators into indices. However, results for this study can be combined with participatory processes to inform summary measure development and set data collection priorities going forward.

Carrie Lyons and co-workers report on population-level indicators of stigma for people with or at risk of HIV infection.     

The DVR gene family in embryonic development.

The DVR gene family consists of at least 15 members, including decapentaplegic from Drosophila, Xenopus Vg1 and the mammalian bone morphogenetic protein genes, encoding secreted proteins closely related to transforming growth factor beta Genetic and biochemical evidence supports the idea that DVR proteins form part of a cascade of extracellular signalling molecules mediating inductive tissue interactions during development.     

The antigen-induced selective recruitment of specific T lymphocytes to the lung

The purpose of the present studies was to investigate the mechanisms by which specific T lymphocytes accumulate in the lung. After the intratracheal (IT) inoculation of influenza virus into guinea pigs, the detection of specific T lymphocytes in the lung coincided with the development of immunity in both hilar nodes and systemic lymphoid tissue. Animals immunized in the footpads with virus failed to develop immune responses in the lung unless rechallenged IT with immunogen. In adoptive transfer experiments, IT inoculation of influenza into nonimmune guinea pigs, followed immediately by the i.v. injection of a mixture of 3H-thymidine-labeled syngeneic T lymphocytes specific for influenza virus and 14C-thymidine-labeled syngeneic T lymphocytes specific for an irrelevant antigen resulted in the selective accumulation of the virus-specific T lymphocytes in the lung. Taken together, these studies indicate that the selective recruitment by antigen of circulating immune cells is one of the mechanisms by which specific T cells accumulate in the lung.     

Attachments by parasitic lampreys within the branchial cavities of their hosts

Silver Lamprey (Ichthyomyzon unicuspis) in the Wisconsin River attached within the branchial cavity of Paddlefish (Polyodon spathula) significantly more often (6.5% of 1,578 attachments) than would be expected by chance on the basis of its relative surface area (3.7%), with as many as four lampreys found together within the branchial cavity of the same Paddlefish. Similar behavior has occasionally been noted for lampreys in other systems, but the phenomenon may be underreported when the lampreys are concealed from view. As suggested previously for some parasitic trychomycterid catfishes, lampreys in the branchial cavity may benefit from accessing blood under pressure, especially in the ventral aorta. In addition, Silver Lamprey within the branchial cavities of Paddlefish may be relatively protected from any negative effects that might result from Paddlefish breaching.     

Nuclear protein redistribution in heat-shocked cells

An increase was observed in the total protein mass of nuclei isolated from Chinese hamster ovary cells heated at 45°C or 45.5°C. An increase in the fractional recovery of DNA polymerase α and β, and of DNA topoisomerase activity coincided with this increase in the protein mass of nuclei from heated cells. Nuclear protein mass which was soluble in 2.0 M NaCl decreased 0.5 fold, while DNA-associated and nuclear matrix-associated protein mass increased 2.2 and 3.4 fold, respectively. The results indicate that the increase in nuclear protein mass observed in nuclei from heated cells is due in part to an increased binding, or precipitation, of nuclear proteins onto the cell's DNA and nuclear matrix. © 1993 Wiley-Liss, Inc.