Search

The metabolome of the model species Chlamydomonas reinhardtii has been analyzed during 120 h of sulfur depletion to induce anaerobic hydrogen (H(2)) production, using NMR spectroscopy, gas chromatography coupled to mass spectrometry, and TLC. The results indicate that these unicellular green algae consume freshly supplied acetate in the medium to accumulate energy reserves during the first 24 h of sulfur depletion. In addition to the previously reported accumulation of starch, large amounts of triacylglycerides were deposited in the cells. During the early 24- to 72-h time period fermentative energy metabolism lowered the pH, H(2) was produced, and amino acid levels generally increased. In the final phase from 72 to 120 h, metabolism slowed down leading to a stabilization of pH, even though some starch and most triacylglycerides remained. We conclude that H(2) production does not slow down due to depletion of energy reserves but rather due to loss of essential functions resulting from sulfur depletion or due to a build-up of the toxic fermentative products formate and ethanol.

OBJECTIVE: The objective of the study was to explore the maternal-fetal pharmacokinetics of intraamniotic (IA), intravenous (IV), or intramuscular (IM) administration of erythromycin or azithromycin in a pregnant sheep model. STUDY DESIGN: Pregnant ewes of 115-121 days’ gestation received a single maternal IV infusion (5 mg/kg over 60 min), a single IM injection, or a single IA injection (3.2 mg/kg fetal weight) of either erythromycin lactobionate or azithromycin. Maternal/fetal blood and amniotic fluid (AF) samples were collected across 48 h for macrolide assay by liquid chromatography and tandem mass spectrometry. RESULTS: Maternal administration achieved therapeutic maternal plasma macrolide concentrations (0.5 g/mL) with low concentrations in AF equivalent to less than 7% transfer; fetal plasma levels were even lower (1.5% transfer). The IA administration achieved therapeutic concentrations in AF and sustained for 48 h, with poor maternal-fetal transfer (1% maternal, 0.3% fetal). Modest pharmacokinetic differences were evident between erythromycin and azithromycin. CONCLUSION: Maternal macrolide administration achieves subtherapeutic concentrations in AF or fetal plasma, whereas a single IA injection achieves therapeutic concentrations in AF but not in maternal-fetal circulations. Combined maternal and single IA administration of macrolides may be a more effective regimen for treatment of intrauterine, but not fetal, infection.