Association between high-fat diet feeding and male fertility in high reproductive performance mice.

The increasing worldwide prevalence of metabolic syndrome (MetS), especially in younger populations, is a risk factor for fertility disorders. However, a direct correlation of MetS with male infertility still remains unclear. In this work, we evaluated whether MetS has a negative impact on fertility of hybrid male mice with high reproductive performance. To induce a MetS-like condition, (C57BL/6xBALB/c) F1 male mice were fed a high-fat diet (HFD, 30% fat) for 19 weeks, while controls received a normal-fat diet (NFD, 6% fat). HFD-fed animals exhibited increased body weight, hypercholesterolemia, hyperglycemia and glucose intolerance. In vivo fertilisation assays performed along the treatment period showed no differences in fertilisation nor in vitro embryo development rates between groups. While testicular weight and morphology were similar in both groups, HFD-fed mice presented lighter epididymides and higher amounts of gonadal fat. Moreover, sperm count was lower in HFD-fed mice, despite normal sperm viability, morphology, motility or acrosome reaction. Finally, no differences were observed in in vitro fertilisation rates between groups. In summary, although HFD feeding altered some reproductive parameters, it did not impair male fertility in high performance breeders suggesting the possibility that a fertility impairment could be the result of the cumulative combination of environmental and/or genetic factors.

Manual MGIT™ system for the detection of Mycobacterium tuberculosis: insights from a high TB burden setting.

OBJECTIVE: To evaluate the diagnostic performance of manual MGIT™ (MMGIT) compared to the gold standard, Löwenstein-Jensen (LJ), in the diagnosis of pulmonary tuberculosis (TB) in a high-burden setting. METHODS: Individuals with suspected TB enrolled in parallel diagnostic trials during 2007-2011 were included. Two samples were obtained from each patient and inoculated into MMGIT and LJ medium. Diagnostic tests were performed, and the incremental yield of a second test and time to detection (TTD) were calculated. Analyses were performed per patient and per sample. Gold standard was based on LJ culture. RESULTS: In the per patient and per sample analysis, we evaluated 1436 patients and 4142 samples. The sensitivity and specificity for smear and MMGIT per sample were respectively 89.9%/92.2% and 97.1%/98.9%. Contamination was observed in 1.4% of samples on MMGIT. The mean TTD (days) was 11.8 for MMGIT and 22.9 for LJ. The sensitivity and specificity for smear and MMGIT per patient were respectively 89.9% and 92.2% and 97.1% and 98.3%. A second MMGIT culture had an incremental yield of 1.6%. CONCLUSIONS: MMGIT has high sensitivity and specificity, regardless of smear result, with a 50% reduction in TTD compared to LJ. These features make MMGIT an acceptable TB diagnostic method for use in resource-limited settings.

Oxygen diffusion-concentration in erythrocyte plasma membranes studied by the fluorescence quenching of anionic and cationic pyrene derivatives.

Fluorescence quenching by oxygen of cationic [pyrene-(CH2)nN(CH3)3+; n = 1, 4, and 11] and anionic [pyrene-(CH2)nCO2-, n = 3, 8, 11, and 15] probes was investigated in erythrocyte plasma membranes (leaky) in order to assess the ability of oxygen molecules to interact with solutes located at different positions in the membrane. The pseudounimolecular quenching rate constants measured increase, both for cationic and anionic probes, when n increases. These results are interpreted in terms of an increased oxygen solubility toward the center of the membrane interior, and imply that lateral diffusion contributes more than transverse diffusion to total oxygen mobility. For all of the probes considered, quenching rates increase when n-alkanols are added. The effect observed increases when n decreases and when the size of the n-alkanol alkyl chain increases. Arrhenius-type plots for the quenching rate constants show noticeable downward curvatures. Average (0-40 degrees C) activation energies are approximately 6 kcal/mol.

On the characteristics of the visible chemiluminescence following free radical lipid peroxidation.

The characteristics of the visible luminescence that follows the lipid peroxidative process were investigated either in the autoxidation of rat brain homogenates or in the azo-bis-amidinopropane initiated lipid peroxidation of erythrocyte plasma membranes and liver microsomes. In these systems the luminescence decay observed after total inhibition of the lipid peroxidation is not an iron-catalyzed process, and follows a complex kinetics comprising fast and slow components. The slow component of the decay lasts for several hours at 27 degrees C and amounts to nearly half of the total intensity measured prior to the inhibition of the oxidative process by propyl gallate. The addition of thiols (diethyldithiocarbamate, penicillamine or dithiothreitol) to a lipid peroxidizing system inhibits the chain oxidation and catalyzes the dark decomposition of one (or several) of the luminescence precursors, following first order kinetics. The effect of temperature on the slow luminescence decay corresponds to an activation energy of 18.5 kcal/mol.

Antioxidant capacity of desferrioxamine and ferrioxamine in the chemically-initiated lipid peroxidation of rat erythrocyte ghost membranes.

2,2'-Azo-bis-(2-amidinopropane) induces the thermal lipid peroxidation of red blood cells membranes by a mechanism that is not iron dependent. The peroxidation rate, as assessed by oxygen uptake or visible chemiluminescence measurements, can be diminished by micromolar concentrations of desferrioxamine (DF), with a median inhibitory concentration (the concentration of DF that reduces the lipid peroxidation rate to 50% of that observed without scavengers addition) of 10 microM. In these conditions, the DF/Fe3+ (1:2) complex is nearly five times less efficient than DF. The present data show that DF is able to trap the initiator radicals and/or the free radicals involved in the lipid peroxidative chain at micromolar concentrations, range in which the agent cannot be used as a general test for iron involvement.

Visible chemiluminescence from rat brain homogenates undergoing autoxidation. II. Kinetics of the luminescence decay.

The visible luminescence emitted in the autoxidation of brain homogenates is only partially quenched when antioxidants are added at concentrations such that further oxidation is prevented. From the time course of the emission after antioxidant addition, it can be estimated that nearly 50% of the light arises from an intermediate that decays with a first order kinetics and with a lifetime of ca. 40 s at 32 degrees C. The remaining light arises from the decomposition of one or several intermediates, and show a kinetics that is independent of the incubation time. From the data obtained it is concluded that bimolecular free radical processes, such as the recombination of peroxy radicals, do not significantly contribute to the observed luminescence.

Visible chemiluminescence from rat brain homogenates undergoing autoxidation. I. Effect of additives and products accumulation.

Rat brain homogenate autoxidation was assessed from thiobarbituric acid reactant accumulation (TBAR), light emission, and oxygen uptake. The effect of several additives upon TBAR accumulation and light intensity suggests that these parameters can be employed as a reliable measure of the lipoperoxidation extent. From the different time profiles of TBAR accumulation and light emission, it is concluded that instantaneous light emission is not a measure of the lipoperoxidation rate but it is related to the accumulation of products. The time dependence of the light emitted after addition to an incubated sample of an excess of free radical scavengers indicates that at least two intermediates of widely different lifetimes are contributing to the observed light emission.