Molecular mechanism of reduction in pregnenolone synthesis by cigarette smoke

Pharmacological regulation of the cholesterol transport machinery in steroidogenic cells of the testis

Reduced serum testosterone (T), or hypogonadism, is estimated to affect about 5 million American men, including both aging and young men. Low serum T has been linked to mood changes, worsening cognition, fatigue, depression, decreased lean body mass and bone mineral density, increased visceral fat, metabolic syndrome, decreased libido, and sexual dysfunction. Administering exogenous T, known as T-replacement therapy (TRT), reverses many of the symptoms of low T levels. However, this treatment can result in luteinizing hormone suppression which, in turn, can lead to reduced sperm numbers and infertility, making TRT inappropriate for men who wish to father children. Additionally, TRT may result in supraphysiologic T levels, skin irritation, and T transfer to others upon contact; and there may be increased risk of prostate cancer and cardiovascular disease, particularly in aging men. Therefore, the development of alternate therapies for treating hypogonadism would be highly desirable. To do so requires greater understanding of the series of steps leading to T formation and how they are regulated, and the identification of key steps that are amenable to pharmacological modulation so as to induce T production. We review herein our current understanding of mechanisms underlying the pharmacological induction of T formation in hypogonadal testis.

Pronounced risk of nontraumatic osteonecrosis of the femoral head among cigarette smokers who have never used oral corticosteroids: a multicenter case-control study in Japan

BACKGROUND

Cigarette smoking has been linked to an increased risk of nontraumatic osteonecrosis of the femoral head (ONFH) in previous studies. However, the effect of smoking amount, duration and cessation, and interaction with corticosteroids remains unclear. The purpose of this study was to precisely evaluate the effects of smoking and the interaction with corticosteroid use.

METHODS

This was a multicenter, matched case-control study in Japan. Cases were defined as patients who were newly diagnosed with ONFH at an initial visit or during the previous year if they were referred patients. For each case, matched controls were selected from patients without ONFH. The matching conditions were sex, age, and ethnicity. A logistic regression model was used to compute odds ratios (OR) and 95 % confidence intervals (95 % CI).

RESULTS

We compared 72 cases with 244 matched controls. ORs were 3.89 (95 % CI 1.46-10.4) for current smokers, 3.89 (1.22-12.4) for smokers consuming more than 20 cigarettes per day, 4.26 (1.32-13.7) for smokers with 26 pack-years or more, and 3.11 (0.92-11.5) for smokers with a history of 29 years or more, with significant or marginally significant dose-response relationships. OR for current smokers was 10.3 among those who had never used corticosteroids and 1.56 among past or current corticosteroid users (P for interaction 0.010).

CONCLUSIONS

Our results revealed that heavier cigarette smoking was associated with a higher risk of ONFH. The elevated risk from cigarette smoking was markedly pronounced among those who had never used oral corticosteroids.

Evaluation of in vitro assays for assessing the toxicity of cigarette smoke and smokeless tobacco

BACKGROUND

In vitro toxicology studies of tobacco and tobacco smoke have been used to understand why tobacco use causes cancer and to assess the toxicologic impact of tobacco product design changes. The need for toxicology studies has been heightened given the Food and Drug Administration's newly granted authority over tobacco products for mandating tobacco product performance standards and evaluate manufacturers' health claims about modified tobacco products. The goal of this review is to critically evaluate in vitro toxicology methods related to cancer for assessing tobacco products and to identify related research gaps.

METHODS

PubMed database searches were used to identify tobacco-related in vitro toxicology studies published since 1980. Articles published before 1980 with high relevance also were identified. The data were compiled to examine (a) the goals of the study, (b) the methods for collecting test substances, (c) experimental designs, (d) toxicologic end points, and (e) relevance to cancer risk.

RESULTS

A variety of in vitro assays are available to assess tobacco smoke that address different modes of action, mostly using non-human cell models. However, smokeless tobacco products perform poorly in these assays. Although reliable as a screening tool for qualitative assessments, the available in vitro assays have been poorly validated for quantitative comparisons of different tobacco products. Assay batteries have not been developed, although they exist for nontobacco assessments. Extrapolating data from in vitro studies to human risks remains hypothetical.

CONCLUSIONS

In vitro toxicology methods are useful for screening toxicity, but better methods are needed for today's context of regulation and evaluation of health claims.