Left ventricular filling pressure in male patients with type 2 diabetes and normal versus low total testosterone levels

Background: Heart failure is a common complication of diabetes characterized by an elevation in left ventricular filling pressures (LVF) that often develops in the absence of clinical symptoms. Diastolic dysfunction in the setting of low total testosterone (LTT) occurs through changes in the regulation of peripheral hemodynamics. LTT is highly prevalent among individuals with type 2 diabetes. The aim of this study was to compare LVF in male diabetic pa­tients with no structural heart disease and normal serum testosterone levels vs. those with LTT. Methods: Type 2 diabetic patients were assessed using tissue Doppler imaging to evalu­ate LVF and other conventional parameters of diastolic function. The E/e’ ratio was used to estimate LVF through the ratio of peak passive trans-mitral left ventricular inflow velocity to the peak passive inflow velocity at the lateral mitral annulus. Patients were assigned to one of two groups based upon their total testosterone levels. Group A consisted of low (< 3.5 ng/mL) testosterone levels and group B consisted of normal (> 3.5 ng/mL) testosterone levels. Results: A total of 148 male patients were included: group A — 47 (32%) patients; group B — 101 (68%) patients, respectively. Mean age was 58 ± 5.8 years and mean time of diabetes evolution was 7 ± 3.1 years. There were no significant differences between the groups regarding age, duration of diabetes evolution, hypertension, weight, heart rate, body mass index, and echocardiographic parameters. The E/e’ ratio for group A was 8.05 ± 1.9 vs. 6.1 ± 1.7 for group B (p < 0.0001). The E/A ratio was 0.94 ± 0.10 vs. 1.19 ± 0.12 (p = 0.01), deceleration time 242 ± 7.4 ms vs. 205 ± 9 ms (p = 0.026) and systolic pulmonary artery pressure 27 ± ± 2.2 mm Hg vs. 22 ± 1.7 mm Hg (p = 0.11). Conclusions: Patients with type 2 diabetes and LTT have a higher E/e’ ratio demonstrating a pre-clinical increase in LVF when compared to similar patients with normal testosterone levels. This finding is independent of time of diabetes evolution, hypertension and other echocardiographic parameters

Mechanisms of Allergen-Antibody Interaction of Cockroach Allergen Bla g 2 with Monoclonal Antibodies That Inhibit IgE Antibody Binding

BACKGROUND: Cockroach allergy is strongly associated with asthma, and involves the production of IgE antibodies against inhaled allergens. Reports of conformational epitopes on inhaled allergens are limited. The conformational epitopes for two specific monoclonal antibodies (mAb) that interfere with IgE antibody binding were identified by X-ray crystallography on opposite sites of the quasi-symmetrical cockroach allergen Bla g 2. METHODOLOGY/PRINCIPAL FINDINGS: Mutational analysis of selected residues in both epitopes was performed based on the X-ray crystal structures of the allergen with mAb Fab/Fab' fragments, to investigate the structural basis of allergen-antibody interactions. The epitopes of Bla g 2 for the mAb 7C11 or 4C3 were mutated, and the mutants were analyzed by SDS-PAGE, circular dichroism, and/or mass spectrometry. Mutants were tested for mAb and IgE antibody binding by ELISA and fluorescent multiplex array. Single or multiple mutations of five residues from both epitopes resulted in almost complete loss of mAb binding, without affecting the overall folding of the allergen. Preventing glycosylation by mutation N268Q reduced IgE binding, indicating a role of carbohydrates in the interaction. Cation-π interactions, as well as electrostatic and hydrophobic interactions, were important for mAb and IgE antibody binding. Quantitative differences in the effects of mutations on IgE antibody binding were observed, suggesting heterogeneity in epitope recognition among cockroach allergic patients. CONCLUSIONS/SIGNIFICANCE: Analysis by site-directed mutagenesis of epitopes identified by X-ray crystallography revealed an overlap between monoclonal and IgE antibody binding sites and provided insight into the B cell repertoire to Bla g 2 and the mechanisms of allergen-antibody recognition, including involvement of carbohydrates

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Atom-atom structure factors of hydrogen halides: A molecular approach revisited

6 pags., 5 figs., 3 tabs.The aim of this paper is to explore the possibilities of a novel molecular integral equation approach to produce information on the atom-atom microscopic structure of molecular fluids via multidimensional integration of the molecular pair distribution function. In particular, atom-atom structure factors for hydrogen halides (HCl and HI) are computed from the integral equation for heteronuclear fluids modeled by a two-center Lennard-Jones potential with and without multipole terms. Theoretical results are compared both with experimental partial structure factors and computer simulation results. Theory and simulation agree remarkably well both for thermodynamics and microscopic structure. The comparison with experimental partial structure factors is satisfactory within the limitations due to the rough modeling used for describing the real fluid. © 1995 American Institute of Physics.This research was financially supported by the Spanish Direccion General de Investigacion Cientıfica y Tecnica ~DGICYT! under Grant No. PB91-0110