Dihydrotestosterone: Biochemistry, Physiology, and Clinical Implications of Elevated Blood Levels.

Benefits associated with lowered serum DHT levels after 5α-reductase inhibitor (5AR-I) therapy in men have contributed to a misconception that circulating DHT levels are an important stimulus for androgenic action in target tissues (e.g., prostate).

Specificity and predictive value of circulating testosterone assessed by tandem mass spectrometry for the diagnosis of polycystic ovary syndrome by the National Institutes of Health 1990 criteria.

Objective: To determine whether liquid chromatography-tandem mass spectrometry (LC-MS/MS) determination of total (TT) and free (FT) testosterone is more specific than extraction chromatography-radioimmunoassay (RIA) for distinguishing women with polycystic ovary syndrome (PCOS) from controls and whether differing cutoff values should be used depending on the setting.

Design: Prospective case-control cohort study.

Setting: Tertiary care center and reference laboratory.

Novel lipoprotein subfraction and size measurements in prediction of mortality in maintenance hemodialysis patients.

Background And Objectives: Conventional lipid profiles usually cannot predict cardiovascular outcomes in chronic disease states. We hypothesized that novel lipoprotein subfraction concentrations and LDL particle size measurements better predict mortality in maintenance hemodialysis (MHD) patients.

Design, Setting, Participants, & Measurements: Mortality-predictability of LDL particle diameter and lipoprotein subfraction concentrations, measured by novel ion mobility, was examined in a cohort of 235 hemodialysis patients who were followed for up to 6 years using Cox models with adjustment for important covariables.

Well differentiated follicular thyroid neoplasia: impact of molecular and technological advances on detection, monitoring and treatment.

Our understanding of the molecular mechanisms responsible for follicular thyroid cell oncogenesis has been advanced significantly in recent years. Specific genetic alterations and the molecular pathways they affect have been associated with particular histologic subtypes of well-differentiated thyroid cancer and are now being evaluated for their utility as clinical tools with diagnostic, prognostic and even therapeutic relevance. This paper focuses on the most common and clinically relevant genetic alterations shown to be consistently associated with well-differentiated thyroid carcinoma.

Validation of a total testosterone assay using high-turbulence liquid chromatography tandem mass spectrometry: total and free testosterone reference ranges.

Accurate measurement of testosterone concentration is of critical importance when diagnosing and treating male hypogonadism, congenital adrenal hyperplasia, premature or delayed puberty, and androgen excess in polycystic ovary syndrome or other virilizing conditions. However, some assays have inherent limitations and biases that affect measurement of low-testosterone values. Therefore, we developed a highly specific online mass spectrometry method.

Ion mobility analysis of lipoprotein subfractions identifies three independent axes of cardiovascular risk.

Objective: Whereas epidemiological studies show that levels of low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) predict incident cardiovascular disease (CVD), there is limited evidence relating lipoprotein subfractions and composite measures of subfractions to risk for CVD in prospective cohort studies.

Methods And Results: We tested whether combinations of lipoprotein subfractions independently predict CVD in a prospective cohort of 4594 initially healthy men and women (the Malmö Diet and Cancer Study, mean follow-up 12.2 years, 377 incident cardiovascular events).

Interlaboratory comparison study of serum total testosterone [corrected] measurements performed by mass spectrometry methods.

Background: Though mass spectrometry (MS) assays are increasingly used for routine clinical measurements of serum total testosterone (TT), information about the variability of results is limited. This study assessed the variability of TT measurement results from routine MS assays.

Methods: Twenty serum samples (12 females, 8 males) were analyzed on 2 days by seven high performance liquid chromatography (HPLC), and one gas chromatography (GC)-tandem mass spectrometry (HPLC-MS/MS, GC-MS/MS) assays.

Direct determination of lipoprotein particle sizes and concentrations by ion mobility analysis.

Background: Current methods for measuring the concentrations of lipoprotein particles and their distributions in particle subpopulations are not standardized. We describe here and validate a new gas-phase differential electrophoretic macromolecular mobility-based method (ion mobility, or IM) for direct quantification of lipoprotein particles, from small, dense HDL to large, buoyant, very-low-density lipoprotein (VLDL).

Methods: After an ultracentrifugation step to remove albumin, we determined the size and concentrations of lipoprotein particles in serum samples using IM.

Evidence for a role of glycogen synthase kinase-3 beta in rodent spermatogenesis.

Glycogen synthase kinase-3 beta (GSK-3 beta) regulates cell metabolism, cell cycle, and cell fate through the phosphorylation of a diverse array of substrates. Herein, we provide evidence that supports a role for GSK-3 in mammalian meiosis and spermatogenesis. Immunostaining of testis sections showed that while GSK-3 alpha was ubiquitous in the seminiferous tubules, GSK-3 beta was expressed in premeiotic type B spermatogonia, in both meiotic preleptotene and leptotene spermatocytes, as well as in Sertoli cells in both the mouse and rat.

Spermatogenetic expression of RNA-binding motif protein 7, a protein that interacts with splicing factors.

We have previously shown that a ubiquitously expressed RNA splicing factor, RNA-binding motif 7 (RBM7), cloned from a testis complementary DNA library, enhances messenger RNA (mRNA) splicing in vitro and is expressed in a cell-restricted fashion. Herein, we detail its mRNA and protein expression in the rodent testis. RNA in situ hybridization shows that Rbm7 expression in rat germ cells closely parallels the entry and progression of meiosis.