Quantitative determination of nitroglycerin in human plasma by capillary gas chromatography negative ion chemical ionization mass spectrometry

A quantitative method for determination of nitroglycerin in human plasma was developed. Nitroglycerin and the internal standard (butane-1,2,4-triyl trinitrate) were extracted from plasma with pentane. The extracts were analysed by gas chromatography mass spectrometry using fused silica capillary columns and electron capture negative ion chemical ionization. The quantitation limit of the method was about 50 pg ml-1. Linear calibration curves were obtained in the range of 50-1600 pg ml-1. Precision at the level of 100 pg ml-1 was 4%.     

Blood leukocyte and spleen lymphocyte immune responses in chronically physically active and sedentary hamsters

This study was designed to evaluate the effects of chronic physical activity on the immune response of spleen lymphocytes and whole blood leukocytes of hamsters. Animals were kept sedentary or allowed to exercise spontaneously on running wheels for eight weeks. Physically active animals averaged 12 kilometers per day. The immune response of spleen lymphocytes and whole blood leukocytes was evaluated by 3H-thymidine incorporation in response to Concanavalin A or lipopolysaccharide. There was no treatment effect between physically active and sedentary hamsters in the response of spleen lymphocytes. The immune response of whole blood leukocytes to these mitogens was significantly greater (p less than 0.05) in physically active vs. sedentary hamsters. These results demonstrate that chronic physical activity has the capacity to modulate immunoresponses.     

Urbanicity and Paediatric Bacteraemia in Ghana—A Case-Control Study within a Rural-Urban Transition Zone

Background

Systemic bacterial infections are a major cause of paediatric febrile illness in sub-Saharan Africa. Aim of this study was to assess the effects of social and geographical determinants on the risk of bacteraemia in a rural-urban transition zone in Ghana.

Methods

Children below 15 years of age with fever were recruited at an outpatient department in the suburban belt of Kumasi, Ghana’s second largest city. Blood was taken for bacterial culture and malaria diagnostics. The socio-economic status of participants was calculated using Principle Component Analysis. A scale, based on key urban characteristics, was established to quantify urbanicity for all communities in the hospital catchment area. A case-control analysis was conducted, where children with and without bacteraemia were cases and controls, respectively.

Results

Bacteraemia was detected in 72 (3.1%) of 2,306 hospital visits. Non-typhoidal Salmonella (NTS; n = 24; 33.3%) and Salmonella typhi (n = 18; 25.0%) were the most common isolates. Logistic regression analysis showed that bacteraemia was negatively associated with urbanicity (odds ratio [OR] = 0.8; 95% confidence interval [CI]: 0.7–1.0) and socio-economic status (OR = 0.8; 95% CI: 0.6–0.9). Both associations were stronger if only NTS infections were used as cases (OR = 0.5; 95% CI: 0.3–0.8 and OR = 0.6; 95% CI: 0.4–1.0, respectively).

Conclusions

The results of this study highlight the importance of individual as well as community factors as independent risk factors for invasive bacterial infection (IBI) and especially NTS. Epidemiological data support physicians, public health experts and policy makers to identify disease prevention and treatment needs in order to secure public health in the transitional societies of developing countries.     

Plasma free and sulfoconjugated catecholamines during sustained exercise

Previous research established a relationship between circulating sulfoconjugated norepinephrine (NE-SO4) and oxygen consumption at various exercise intensities. In this study, the stability of the NE-SO4 response was examined during sustained exercise at a constant relative intensity. Seven trained men bicycled at 78 +/- 3% of their maximal O2 consumption for 28 min and then rested on the ergometer for a comparable duration. After a 30-min rest, plasma samples were collected through an indwelling catheter at 7-min intervals during the exercise and recovery periods. Free NE and epinephrine increased sixfold during exercise. These changes were accompanied by increases in sulfoconjugated catecholamines, but only NE-SO4 achieved statistical significance (rest, 712 +/- 602; exercise, 1,329 +/- 1,163 pg/ml). This occurred at three collection periods (14, 21, and 28 min). Approximately 35, 52, and 95% of NE, epinephrine, and dopamine, respectively, existed as sulfoconjugated during exercise. Subject variation was present in the sulfoconjugated catecholamine response that could not be attributed to corresponding differences in circulating free catecholamine release. These findings implicate blood flow as a factor in the sulfoconjugation of NE, but not epinephrine or dopamine.     

Plasma free and sulfoconjugated catecholamine responses to varying exercise intensity

Plasma free catecholamines rise during exercise, but sulfoconjugated catecholamines reportedly fall. This study examined the relationship between exercise intensity and circulating levels of sulfoconjugated norepinephrine, epinephrine, and dopamine. Seven exercise-trained men biked at approximately 30, 60, and 90% of their individual maximal oxygen consumption (VO2max) for 8 min. The 90% VO2max period resulted in significantly increased plasma free norepinephrine (rest, 219 +/- 85; exercise, 2,738 +/- 1,149 pg/ml; P less than or equal to 0.01) and epinephrine (rest, 49 +/- 49; exercise, 555 +/- 516 pg/ml; P less than or equal to 0.05). These changes were accompanied by consistent increases in sulfoconjugated norepinephrine at both the 60% (rest, 852 +/- 292; exercise, 1,431 +/- 639; P less than or equal to 0.05) and 90% (rest, 859 +/- 311; exercise, 2,223 +/- 1,015; P less than or equal to 0.05) VO2max periods. Plasma sulfoconjugated epinephrine and dopamine displayed erratic changes at the three exercise intensities. These findings suggest that sulfoconjugated norepinephrine rises during high-intensity exercise.