The growth of microorganisms in total parenteral nutrition admixtures

Total nutrient admixtures (TNAs) containing glucose, amino acids, and lipid emulsion in one container and amino acid/dextrose solutions [conventional total parenteral nutrition (TPN) formulations] were studied in a controlled laboratory experiment for their ability to support the growth of microorganisms. Both TNA and conventional TPN formulations for peripheral and central venous administration with standard additives were inoculated with microorganisms to provide 10(1)-10(2) colony-forming units/ml (CFU/ml) of Staphylococcus epidermidis, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Candida albicans. The admixtures were stored at room temperature and samples for quantitative microbiology were taken at time 0, 6, 12, 24, 48, 72, and 96 hr. K. pneumoniae, E. coli, and P. aeruginosa were able to proliferate in central TNAs, but the growth of these organisms was retarded in conventional TPN solutions. In the peripheral formulations, K. pneumoniae and E. coli proliferated in both the TNA and conventional TPN systems, whereas P. aeruginosa grew well only in the peripheral TNA. S. epidermidis was not able to grow in any admixtures tested; however, C. albicans grew well in all admixtures, but growth was slower in the conventional central TPN. In conclusion, peripheral and central TNAs supported the growth of microorganisms significantly better than conventional TPN solutions.     

Plasma endothelin-1 release during acute stress: role of ethnicity and sex

OBJECTIVES: The purposes of this study were to examine possible ethnic and sex differences in plasma ET-1 levels at rest and in response to acute stress and to examine relationships between ET-1 and vasoconstrictive-mediated BP reactivity to stress. METHODS: Two hundred twenty-two adolescents (mean age = 18.5 +/- 2.8 years; 130 [70 males] EAs and 92 [48 males] AAs) completed two stressors (video game, forehead cold). Hemodynamic measures and blood samples were collected at catheter insertion and before and immediately after the two stressors, separated by 20-minute rest periods. RESULTS: AAs and males exhibited higher levels of SBP and DBP and of TPRI and ET-1 at each sampling point compared with EAs and females, respectively (p values <.001). AAs and males exhibited greater increases in SBP, TPRI, and ET-1 in response to each stressor (p values <.05). Intraindividual correlations between ET-1 and hemodynamic parameters revealed that most individuals exhibited a positive association between ET-1, BP, and TPRI. However, some individuals exhibited a negative association between ET-1 and the above-mentioned hemodynamics, suggesting a compensatory vasodilation mechanism. CONCLUSION: The findings demonstrate significant sex and ethnicity differences in stress-induced vasoconstrictive peptide release and support the hypothesis that these differences may be important in explaining the ethnicity and sex differences in the prevalence of cardiovascular disease.