Favourable association of leg fat with cardiovascular risk factors.

OBJECTIVES: To assess the association of trunk and leg fat mass (FM) and leg lean tissue mass (LTM) with conventional cardiovascular risk factors. DESIGN: Cross-sectional study. SETTING AND SUBJECTS: We studied 1249 men and 3007 women (age 20-79 years) who attended a research institute for a health checkup between October 1995 and February 2004. MAIN OUTCOME MEASURES: Body mass index, waist circumference (WC), hip circumference (HC), systolic and diastolic blood pressure, total cholesterol, HDL cholesterol, triglycerides, glucose and haemoglobin A(1C) were measured. Trunk FM, leg FM and leg LTM were obtained by dual-energy X-ray absorptiometry. We evaluated the associations between the indices for regional body composition and cardiovascular risk factors, which included hypertension, hypercholesterolaemia, hypo-HDL cholesterolaemia, hypertriglyceridaemia, dyslipidaemia and diabetes mellitus. RESULTS: Increase in WC and HC respectively showed increase and decrease in odds ratios of cardiovascular risk factors. Increase in trunk FM by 1 kg significantly increased the risk of the cardiovascular risk factors with the odds ratios ranging between 1.11 and 1.45. Increase in leg FM by 1 kg significantly decreased the risk with the odds ratios ranging between 0.52 and 0.90, except for the nonsignificant results for hypercholesterolaemia and hypo-HDL cholesterolaemia in men. Odds ratios of 1 kg increase in leg LTM were only significant for dyslipidaemia in men and hypercholesterolaemia in women (both 0.93). CONCLUSIONS: WC and HC showed opposite and independent associations with cardiovascular risk factors. The favourable association of HC was mainly attributable to that of leg FM.

Excess accumulation of body fat is related to dyslipidemia in normal-weight subjects.

OBJECTIVE: To assess the relationship of fat mass (FM) and its distribution to hypertension and dyslipidemia in normal-weight Japanese individuals. DESIGN: Cross-sectional study. SUBJECTS: Apparently healthy Japanese subjects with a body mass index (BMI) between 20 and 23.5 kg/m(2) (265 males and 741 females, age 21-69 y). MEASUREMENTS: BMI, waist circumference (WC), waist-hip ratio (WHR), systolic and diastolic blood pressure, serum levels of total cholesterol (TC), high-density lipoprotein-cholesterol (HDL-C) and triglyceride (TG) were measured. Low-density lipoprotein-cholesterol (LDL-C) was calculated by the Friedewald formula. Percentage fat mass (%FM) and trunk fat mass-leg fat mass ratio (FM(trunk)/FM(legs)) were obtained by dual-energy X-ray absorptiometry. RESULTS: WC, WHR, %FM and FM(trunk)/FM(legs) were significantly correlated with TC, LDL-C, HDL-C and TG with the tendency of FM(trunk)/FM(legs) to show the strongest correlations. For %FM and FM(trunk)/FM(legs) in both sexes, odds ratios (ORs) of the third tertiles with respect to the first tertiles increased for LDL-C elevation, TG elevation and dyslipidemia. In males, ORs of the third tertiles of WC were significantly high for LDL-C elevation and dyslipidemia whereas those of WHR were high for TG elevation and dyslipidemia. ORs of the third tertiles of WC and WHR were significantly high for TG elevation in females. BMI was not associated with the risk of abnormal lipid levels. ORs for hypertension showed significant increases in none of the variables of obesity. CONCLUSIONS: Excess accumulation of FM, especially to the upper body, was related to dyslipidemia in normal-weight subjects. Simple anthropometric variables, WC and WHR, may be useful for screening and management of dyslipidemia in these subjects.

Comparison of stepwise and simultaneous estimations of population pharmacokinetics and pharmacodynamics of TS-943.

The prediction performances of population pharmacokinetic-pharmacodynamic analysis of the two methods (a stepwise and a simultaneous estimations) were evaluated with respect to their accuracies and precisions. A study was designed to investigate the safety and efficacy of TS-943 by a 4 hours constant infusion in 36 healthy male subjects. Population analysis was performed using pharmacokinetic and pharmacodynamic models with NONMEM. The mean of the prediction error (MPE) and the root mean squared error (RMSE) served as a measure of accuracy and precision. In addition, a bootstrap validation was also performed. The results indicate that those population pharmacokinetic-pharmacodynamic parameters for the two methods were comparable. The results of simultaneous estimations are similar to those obtained using a stepwise estimation. The mean parameter estimates obtained with the additional 200 bootstrap replicates of data were within 15% of those obtained with the final model in both methods. The present results demonstrated that the accuracy of pharmacodynamic evaluations using a stepwise end a simultaneous estimations was comparable.

Detection of cardiovascular risk factors by indices of obesity obtained from anthropometry and dual-energy X-ray absorptiometry in Japanese individuals.

OBJECTIVE: To determine the cut-off points of indices of obesity for detecting hypertension, dyslipidemia and diabetes mellitus in Japanese individuals. DESIGN: Cross-sectional study. SUBJECTS: A total of 2728 Japanese individuals (768 males and 1960 females, aged 20-79 y) who attended the Fukuoka Health Promotion Center, Japan for health check-up. MEASUREMENTS: Body mass index (BMI), waist circumference (WC) and waist-hip ratio (WHR) were measured. Percentage fat mass (%FM), trunk fat mass (FM(trunk)) and trunk fat mass-leg fat mass ratio (FM(trunk)/FM(legs)) were obtained by dual-energy X-ray absorptiometry (DXA). Cardiovascular risk factors were determined by blood pressure, serum lipids, fasting blood glucose and hemoglobin A(1C). RESULTS: The cut-off points of BMI, WC and WHR were around 23.5 kg/m(2), 84 cm and 0.9 for males, and 22.5 kg/m(2), 72 cm and 0.8 for females. The cut-off points of %FM, FM(trunk) and FM(trunk)/FM(legs) were around 24%, 8 kg and 1.6 for males, and 35%, 9 kg and 1.4 for females. WHR and FM(trunk)/FM(legs) most accurately detected the risk factors. CONCLUSIONS: For Japanese individuals, the cut-off points for detecting cardiovascular risk factors are lower than the criteria by the World Health Organization. Indices of fat distribution detected the cardiovascular risk factors more accurately than those of overall adiposity. The accuracy of detecting the risk factors was comparable between the anthropometric indices and indices obtained by DXA.

Pharmacokinetic and pharmacodynamic analysis of TS-943, a selective non-peptide platelet glycoprotein-IIb/IIIa (GPIIb/IIIa) receptor antagonist, using a nonlinear mixed effect model in dogs.

A simultaneous analysis of the pharmacokinetics and pharmacodynamics of TS-943, a selective nonpeptide platelet glycoprotein-IIb/IIIa (GPIIb/IIIa) receptor antagonist, was made in dogs using a nonlinear mixed effect model. Plasma concentrations of TS-943 were determined after bolus intravenous injection, constant infusion and bolus plus constant infusion. Pharmacokinetic/pharmacodynamic data were fitted using NONMEM software. The pharmacokinetics of TS-943 fitted a two-compartment open model with first-order elimination. The pharmacodynamic model that best fitted platelet aggregation was an inhibitory sigmoid Emax model. The final estimates for E0 (baseline effect), Emax (maximum effect), IC50 (50% inhibitory concentration) and gamma (Hill coefficient) were 66.3%, 64.3%, 104 ng mL(-1) and 1.37, respectively. Correlations between TS-943 plasma concentration and extension of template bleeding time were examined by fitting with an exponential model. The TS-943 plasma concentration necessary to double bleeding time (C2-BTE) was approximately 209 ng mL(-1). The model estimated that the C2-BTE/IC50 (inhibition of platelet aggregation) ratio was approximately 2.0-fold in dogs. Our results suggest that the ratio values for dogs and man are comparable. A nonlinear mixed effect model was a useful tool for exploring the concentration-effect relationship for both efficacy and safety of TS-943 in dogs and man. In this study, the dog was found to be a useful model for screening of efficacy and safety of TS-943 in man.

Determination of pibutidine metabolites in human plasma by LC-MS/MS.

A novel metabolite-screening procedure for pibutidine. an H2-receptor antagonist, which uses high-performance liquid chromatography/tandem mass spectrometry (LC-MS/MS), demonstrated the presence of pibutidine and its four metabolites in plasma from volunteers who received a single dose of pibutidine hydrochloride. In order to quantitatively examine the metabolism of pibutidine, an assay based on LC-MS/MS was subsequently developed for the simultaneous determination of its metabolites in human plasma. Target analytes consisted of M-5, M-7 and M-8, which were prominently detected by the screening procedure, and M-9, which has pharmacological activity as an H2-receptor antagonist. Metabolites and their deuterated internal standards were extracted from human plasma using an Oasis HLB extraction cartridge, and chromatographed on a Monitor C18M column. No isotope effects on chromatographic retention time were observed for any deuterated compounds, which were ionized using an electrospray ionization (ESI)- interface and detected by MS/MS in the selected reaction-monitoring (SRM) mode simultaneously with the corresponding metabolites. The assay was validated over the concentration range of 0.1 to 25.6 ng ml(-1) and used to determine the plasma levels of metabolites in volunteers following oral administration of a 20-mg dose of pibutidine hydrochloride.

Population pharmacokinetics and pharmacodynamics of TS-943 for selective nonpeptide platelet glycoprotein IIb/IIIa receptor antagonist in normal healthy subjects.

The pharmacokinetics and pharmacodynamics of TS-943 were evaluated with use of NONMEM in 36 healthy male subjects after constant infusion of five different single-dose regimens. Population analysis showed the plasma concentration-time profiles of TS-943 to be best-fit characterized by a two-compartment open model with constant infusion and first-order elimination. The pharmacodynamic model that best fitted the platelet aggregation was a sigmoid Emax model. The final estimates for baseline effect, 50% inhibitory concentration (IC50), and the Hill coefficient were 79.4%, 23.4 ng/mL and 1.63, respectively. The maximum effect (Emax) was fixed at 80% (submaximal aggregation response). In addition, correlations between TS-943 plasma concentration and extension of template bleeding time were examined by fitting with an exponential model. The model estimates that the TS-943 plasma concentration necessary to double template bleeding time is approximately 63 ng/mL (ie, 2.7-fold greater than the IC50). The population approaches for pharmacokinetic-pharmacodynamic investigation can be useful for the analysis of concentration-effect relationships and concentration-adverse event relationships for a platelet glycoprotein IIb/IIIa receptor antagonist.

Development and validation of a liquid chromatographic-tandem mass spectrometric method for the determination of pibutidine in human urine.

A liquid chromatographic-tandem mass spectrometric method for the rapid quantitative determination of pibutidine, an H2-receptor antagonist, in human urine has been developed and validated over the concentration range 0.1-25.6 microg ml(-1). Urine samples were prepared based on a simple dilution with 0.05% acetic acid, followed by reversed-phase liquid chromatographic separation. Pibutidine and its internal standard (2H10-pibutidine) were ionized using an electrospray ionization interface and detected by tandem mass spectrometry in the selected reaction-monitoring mode. Completed validation demonstrated the method to be robust, accurate, precise and specific for the direct quantification of pibutidine in human urine. This method has enabled investigation of the urinary excretion of pibutidine following oral administration of pibutidine hydrochloride to healthy subjects.

Utility of postcolumn addition of 2-(2-methoxyethoxy)ethanol, a signal-enhancing modifier, for metabolite screening with liquid chromatography and negative ion electrospray ionization mass spectrometry.

A strategy for highly sensitive metabolite screening by liquid chromatography-electrospray ionization (ESI) mass spectrometry with the negative-ion mode that involves the use of a reversed-phase column in gradient-elution mode and postcolumn addition of 2-(2-methoxyethoxy)ethanol (2-MEE), a novel signal-enhancing modifier, has been described. When a mobile phase of 50 mM ammonium acetate/acetic acid buffer (pH 4.4) at a flow rate of 100 microL/min was employed, poor ESI response of ibuprofen as a model drug, probably due to both the high surface tension of the mobile phase and the ion-suppression effect of acetate anion in the mobile phase, was observed. On the other hand, the postcolumn addition of 2-MEE (50 microL/min) into the mobile phase counteracted the ion suppression as well as the surface tension problem, resulting in approximately 100-fold signal enhancement of the analyte. The metabolite screening of ibuprofen in human urine was subsequently carried out comparing the results with and without postcolumn addition of 2-MEE. The results indicated that the postcolumn addition of 2-MEE dramatically improved the ESI responses of all urinary metabolites detected without affecting the chromatographic separation.

Ultrasensitive determination of NE-100, a novel sigma ligand, in human plasma by liquid chromatography and electrospray ionization tandem mass spectrometry combined with a column-switching technique.

For the highly sensitive and selective determination of NE-100, a novel sigma ligand, at levels of low picogram per milliliter of human plasma, a method with excellent reliability employing liquid chromatography (LC)-electrospray ionization (ESI) tandem mass spectrometry (MS-MS) combined with a column-switching technique has been developed. The method involves the use of a stable isotope labeled compound as the internal standard (I.S.), liquid-solid extraction of a plasma specimen with a C8 cartridge, automated on-line clean-up on a short trapping column, subsequent separation on a micro-bore C18 column and detection with ESI-MS-MS using m/z 356 ([M+H]+) as a precursor ion and m/z 105 as a product ion in a selected reaction monitoring mode. The detection and the quantification limits of NE-100 in plasma were 0.5 pg/ml with a signal-to-noise ratio (S/N) of 3 and 2.3 pg/ml, respectively, with an S/N of 21. The good linearity of the calibration graph was obtained in the range of 2.3 to approximately 907.0 pg/ml with excellent reliability. The developed method was applied to the determination of NE-100 in plasma obtained from the clinical trail.

Rapid characterization of urinary metabolites of pibutidine hydrochloride in humans by liquid chromatography/electrospray ionization tandem mass spectrometry.

The metabolic products of pibutidine hydrochloride, a new H(2)-receptor antagonist, in human urine after oral administration of 40 mg/man were characterized by high-performance liquid chromatography/tandem mass spectrometry (LC/MS/MS) with electrospray ionization (ESI). Two-stage collision-induced dissociation (CID) experiments, with in-source CID by increasing the octapole offset voltage and collision-cell CID, were performed in order to develop a very rapid screening procedure that enhanced selectivity toward pibutidine-related compounds. It was possible to detect metabolites of pibutidine directly from a crude biological matrix without prior extraction, enabling confirmation of the identity of eight metabolites in urine. In addition, the linear range in ESI for pibutidine-related compounds was studied to determine the urinary excretion of pibutidine and its metabolites in humans.

Determination of gallopamil in human plasma by selected ion monitoring.

A gas chromatographic mass spectrometric procedure using selected ion monitoring is described for the quantification of gallopamil in human plasma. Gas chromatographic separation of gallopamil from phenolic metabolite isomers is made possible by treatment with ethyl chloroformate. The detection limit for the quantitation by the present method is 0.09 ng/ml of plasma. The method has sufficient sensitivity to permit pharmacokinetic studies with human subjects following the oral administration of gallopamil hydrochloride.

Age-related decreases in cardiac receptor control of forearm vascular resistance in humans.

We examined 1) the relationship between the magnitudes of reflex forearm vasoconstriction during lower body negative pressure (LBNP) at -10 mmHg and ages in 59 subjects whose ages ranged from 24 to 77 years old, and 2) the slopes of the regression lines relating changes in forearm vascular resistance and those in central venous pressure in the three age-groups; those younger than 35 years old (n = 15), those between 35 and 55 years old (n = 12) and those older than 55 years old (n = 12). Forearm blood flow was measured using a strain gauge plethysmograph and forearm vascular resistance was calculated from forearm blood flow and mean blood pressure. There was a significant negative correlation (r = -0.512, p less than 0.01) between age and the magnitude of reflex forearm vasoconstriction during LBNP at -10 mmHg. The slope of the regression line in the old age-group was less (p less than 0.05) than that in the young or middle age-group. Forearm vascular responses to the cold pressor test did not differ among the three age-groups. These results suggest that cardiac receptor control of forearm vascular resistance decreases with aging in humans.

Exercise training augments cardiopulmonary baroreflex control of forearm vascular resistance in middle-aged subjects.

Nine subjects (average age 56 +/- 7 years old) underwent sitting cycle ergometer exercise for four months. Exercise capacity and maximal VO2 increased after exercise training in these subjects. Forearm vascular responses to lower body negative pressure (LBNP) at -10 and -40 mmHg were compared before and after exercise training. The magnitude of reflex forearm vasoconstriction in response to LBNP at -10 mmHg was greater after exercise training than before. The decreases in central venous pressure during LBNP at -10 mmHg were similar before and after exercise training. The pressor and forearm vasoconstrictive responses to the cold pressor test also did not differ before and after exercise training. These results suggest that mild exercise training in middle-aged subjects augments the tonic inhibitory influence of the cardiopulmonary receptors on forearm vascular resistance.

Augmented cardiopulmonary baroreflex control of forearm vascular resistance in young athletes.

The aim of this study was to examine the effect of exercise training on reflex control of vascular resistance in human males. Forearm vascular responses to lower body negative pressure (LBNP) at -10 and -40 mm Hg were compared between highly trained young athletes (21.5 +/- 0.5 years old, n = 14) and age-matched nonathletes (20.7 +/- 0.5 years old, n = 16). Resting heart rate was lower in athletes than in nonathletes. Resting blood pressure, central venous pressure, forearm blood flow, and forearm vascular resistance were not different between the two groups. The magnitude of reflex forearm vasoconstriction in response to LBNP at -10 mm Hg, which decreased central venous pressure but did not alter blood pressure or heart rate, was greater in athletes than in nonathletes. The slope of the regression line relating changes in central venous pressure and forearm vascular resistance was steeper in athletes than in nonathletes. Vasoconstrictive responses to intraarterially administered norepinephrine and angiotensin II did not differ between athletes and nonathletes. These results suggest that the tonic inhibitory influence of the cardiopulmonary receptors is augmented in athletes. This augmentation may contribute to some of cardiovascular and endocrine adaptations that occur with exercise training.

Active substance of Histoplasma capsulatum that inhibits blastogenic response of lymphocytes.

A substance inhibiting blast transformation of murine spleen lymphocytes stimulated with various mitogens, such as LPS, PHA, and PWM, was obtained from yeast-form cells of Histoplasma capsulatum. This active substance was partially purified from the cell-free extract by DEAE-Sepharose CL-6B column chromatography. As a result of this partial purification, the inhibitory activity was 1.26 micrograms/ml in terms of ID50. Materials from H. capsulatum also inhibited blast transformation of murine spleen lymphocytes stimulated with the antigen PPD as well as mitogens LPS, PHA, and PWM. However, the con A-induced proliferative response was only slightly affected. A similar result was observed for the MLR. These inhibitory activities were abolished by heating at 70 C for 30 min. These results suggest that the heat-labile active substance produced by H. capsulatum might directly affect the lymphocytes, leading to inhibition of their blast transformation.