Role of CYP27A in cholesterol and bile acid metabolism

The CYP27A gene encodes a mitochondrial cytochrome P450 enzyme, sterol 27-hydroxylase, that is expressed in many different tissues and plays an important role in cholesterol and bile acid metabolism. In humans, CYP27A deficiency leads to cerebrotendinous xanthomatosis. To gain insight into the roles of CYP27A in the regulation of cholesterol and bile acid metabolism, cyp27A gene knockout heterozygous, homozygous, and wild-type littermate mice were studied. In contrast to homozygotes, heterozygotes had increased body weight and were mildly hypercholesterolemic, with increased numbers of lipoprotein particles in the low density lipoprotein size range. Cyp7A expression was not increased in heterozygotes but was in homozygotes, suggesting that parts of the homozygous phenotype are secondary to increased cyp7A expression and activity. Homozygotes exhibited pronounced hepatomegaly and dysregulation in hepatic cholesterol, bile acid, and fatty acid metabolism. Hepatic cholesterol synthesis and synthesis of bile acid intermediates were increased; however, side chain cleavage was impaired, leading to decreased bile salt concentrations in gallbladder bile. Expression of Na-taurocholate cotransporting polypeptide, the major sinusoidal bile salt transporter, was increased, and that of bile salt export pump, the major canalicular bile salt transporter, was decreased. Gender played a modifying role in the homozygous response to cyp27A deficiency, with females being gen

Sense and sensibilities: Schoolboys talk about sex in the private conversational space

This article focuses on the narratives of 18 adolescent boys as they engaged with issues of sex, sexuality and peer relations in their daily lives. The ethnographic research was conducted in two public secondary schools in a working-class community within KwaZulu-Natal, South Africa. Participants were boys aged between 16 and 19 years, who self-identified as either Black African or Indian. Theories of positioning are employed in this paper to delve into the complexity and intricacies of boys enacting their masculinities and sexual identities within a one-to-one interview space with one of the researchers. Identity performance in this private space is read in relation to public positions (in the company of peers), exposing the malleable nature of positioning and its subjective use in different spaces. Findings suggest that boys’ struggle with the concept and social practice of ‘masculinity’, and that while they may not want to be seen as aspiring to certain ideals regarding male sexuality, these values remain a standard against which to evaluate self and other. In the individual interviews, authenticity as a heterosexual man is negotiated through various rhetorical strategies, namely a tendency to self-position as mature and sensible. It is argued that positionality is a useful conceptual tool for highlighting diversities in the performance of masculinities, and that intervention strategies need to pay attention to how spaces are constructed and nurtured for boys to engage with the ideological dilemmas in their identity development

Adolescent girls and young women: key populations for HIV epidemic control.

CAPRISA, 2015.Abstract available in pdf