Fluctuations in depression and well-being are associated with sexual risk episodes among HIV-positive men

Peer reviewedPostprin

Body size and digestive system shape resource selection by ungulates : a cross-taxa test of the forage maturation hypothesis

The forage maturation hypothesis (FMH) states that energy intake for ungulates is maximised when forage biomass is at intermediate levels. Nevertheless, metabolic allometry and different digestive systems suggest that resource selection should vary across ungulate species. By combining GPS relocations with remotely sensed data on forage characteristics and surface water, we quantified the effect of body size and digestive system in determining movements of 30 populations of hindgut fermenters (equids) and ruminants across biomes. Selection for intermediate forage biomass was negatively related to body size, regardless of digestive system. Selection for proximity to surface water was stronger for equids relative to ruminants, regardless of body size. To be more generalisable, we suggest that the FMH explicitly incorporate contingencies in body size and digestive system, with small-bodied ruminants selecting more strongly for potential energy intake, and hindgut fermenters selecting more strongly for surface water.DATA AVAILABILITY STATEMENT : The dataset used in our analyses is available via Dryad repository (https://doi.org/10.5061/dryad.jsxksn09f) following a year-long embargo from publication of the manuscript. The coordinates associated with mountain zebra data are not provided in an effort to protect critically endangered black rhino (Diceros bicornis) locations. Interested researchers can contact the data owner (Minnesota Zoo) directly for inquiries.https://wileyonlinelibrary.com/journal/elehj2022Mammal Research InstituteZoology and Entomolog

Cultivation of Methanogens from Shallow Marine Sediments at Hydrate Ridge, Orego

Little is known about the methanogenic degradation of acetate, the fate of molecular hydrogen and formate or the ability of methanogens to grow and produce methane in cold, anoxic marine sediments. The microbes that produce methane were examined in permanently cold, anoxic marine sediments at Hydrate Ridge (44°35\u27 N, 125°10\u27 W, depth 800 m). Sediment samples (15 to 35 cm deep) were collected from areas of active methane ebullition or areas where methane hydrates occurred. The samples were diluted into enrichment medium with formate, acetate or trimethylamine as catabolic substrate. After 2 years of incubation at 4 °C to 15 °C, enrichment cultures produced methane. PCR amplification and sequencing of the rRNA genes from the highest dilutions with growth suggested that each enrichment culture contained a single strain of methanogen. The level of sequence similarity (91 to 98%) to previously characterized prokaryotes suggested that these methanogens belonged to novel genera or species within the orders Methanomicrobiales and Methanosarcinales. Analysis of the 16S rRNA gene libraries from DNA extracted directly from the sediment samples revealed phylotypes that were either distantly related to cultivated methanogens or possible anaerobic methane oxidizers related to the ANME-1 and ANME-2 groups of the Archaea. However, no methanogenic sequences were detected, suggesting that methanogens represented only a small proportion of the archaeal community

Mechanism of Resistance to Dietary Cholesterol

Background. Alterations in expression of hepatic genes that could contribute to resistance to dietary cholesterol were investigated in Sprague-Dawley rats, which are known to be resistant to the serum cholesterol raising action of dietary cholesterol. Methods. Microarray analysis was used to provide a comprehensive analysis of changes in hepatic gene expression in rats in response to dietary cholesterol. Changes were confirmed by RT-PCR analysis. Western blotting was employed to measure changes in hepatic cholesterol 7α hydroxylase protein. Results. Of the 28,000 genes examined using the Affymetrix rat microarray, relatively few were significantly altered. As expected, decreases were observed for several genes that encode enzymes of the cholesterol biosynthetic pathway. The largest decreases were seen for squalene epoxidase and lanosterol 14α demethylase (CYP 51A1). These changes were confirmed by quantitative RT-PCR. LDL receptor expression was not altered by dietary cholesterol. Critically, the expression of cholesterol 7α hydroxylase, which catalyzes the rate-limiting step in bile acid synthesis, was increased over 4-fold in livers of rats fed diets containing 1% cholesterol. In contrast, mice, which are not resistant to dietary cholesterol, exhibited lower hepatic cholesterol 7α hydroxylase (CYP7A1) protein levels, which were not increased in response to diets containing 2% cholesterol

Mechanism of Resistance to Dietary Cholesterol

Background. Alterations in expression of hepatic genes that could contribute to resistance to dietary cholesterol were investigated in Sprague-Dawley rats, which are known to be resistant to the serum cholesterol raising action of dietary cholesterol. Methods. Microarray analysis was used to provide a comprehensive analysis of changes in hepatic gene expression in rats in response to dietary cholesterol. Changes were confirmed by RT-PCR analysis. Western blotting was employed to measure changes in hepatic cholesterol 7α hydroxylase protein. Results. Of the 28,000 genes examined using the Affymetrix rat microarray, relatively few were significantly altered. As expected, decreases were observed for several genes that encode enzymes of the cholesterol biosynthetic pathway. The largest decreases were seen for squalene epoxidase and lanosterol 14α demethylase (CYP 51A1). These changes were confirmed by quantitative RT-PCR. LDL receptor expression was not altered by dietary cholesterol. Critically, the expression of cholesterol 7α hydroxylase, which catalyzes the rate-limiting step in bile acid synthesis, was increased over 4-fold in livers of rats fed diets containing 1% cholesterol. In contrast, mice, which are not resistant to dietary cholesterol, exhibited lower hepatic cholesterol 7α hydroxylase (CYP7A1) protein levels, which were not increased in response to diets containing 2% cholesterol

Fluctuations in Depression and Well-Being Are Associated with Sexual Risk Episodes Among HIV-Positive Men NIH Public Access Author Manuscript

Abstract Objective-Research has suggested a weak association between depression and sexual risk behavior in men who have sex with men (MSM). The purpose of this study is to investigate the relationship between within-person fluctuations in depression and well-being and episodes of sexual risk-taking among HIV-positive MSM. Methods-One hundred and six sexually active HIV-positive MSM living in New York City completed a structured weekly survey over six weeks. In weeks 1, 3, and 5, they responded to items assessing their sexual behavior, depression and well-being in the prior week. Multi-level logistic regression analyses were conducted to explore the relationship between changes in levels of depression and well-being and episodes of unprotected anal intercourse (UAI). Results-Within-person deviations from participants' average levels of depression and wellbeing were associated with the probability of risk. The probability of a risk episode was higher in weeks when depression was higher than participants' average levels (any UAI episode: OR = 1.71, 95% CI [1.00-2.90], p < .05; serodiscordant UAI episode: OR = 2.49, 95% CI [1.31-4.73], p < . 05). The probability of a risk episode was lower in weeks when well-being was higher than participants' average levels (any UAI: OR = 0.40, 95% CI [0.22-0.74], p < .05; serodiscordant UAI: OR = 0.42, 95% CI [0.22-0.81], p < .05). Between-person differences in depression and well-being were not associated with risk episodes (all ps > .05). Conclusions-This study is among the first to examine the association of within-person changes in depression and well-being with sexual risk behavior in a diverse sample. It contributes new evidence to literature exploring the relationship between depression and sexual risk. Future research should employ longitudinal designs to explore pathways linking within-person changes in depression with risk behavior. Keywords depression; well-being; HIV/AIDS; men who have sex with men; sexual risk behavio