Effect of nutritional constraints on the biosynthesis of the components of the phosphoenolpyruvate: sugar phosphotransferase system in a fresh isolate of Streptococcus mutans.

A procedure for the purification of enzyme I (EI) and the protein HPr, the general components of the phosphoenolpyruvate:sugar phosphotransferase system, from Streptococcus mutans serotype c is presented. The method was also applied successfully to the purification of EI and HPr from Streptococcus salivarius, Streptococcus sobrinus, and Streptococcus sanguis. Using specific antibodies obtained against the proteins purified from S. mutans DR0001, we determined quantitatively by rocket electrophoresis the cellular levels of EI and HPr in a freshly isolated strain of S. mutans grown under various conditions in continuous culture. The activity of a few specific EIIs was also determined by an in vitro phosphorylation test. Results indicated that maximum EII activities for glucose, mannose, and 2-deoxyglucose were obtained under conditions of glucose limitation, at pH 7.0 and low dilution rate (D = 0.057/h). Increasing the amount of glucose or the dilution rate (D = 0.40/h) or decreasing the pH from 7.0 to 5.5 resulted in a 1.4- to 24-fold decrease in these activities. The EII activity for fructose was not influenced by the growth conditions in the same way as the other EIIs. The fructose EII was highest at pH 5.5 and at high dilution rate under conditions of glucose or nitrogen limitation and was always repressed at pH 7.0 and at low dilution rates. The intracellular levels of EI were also dependent on the growth conditions. The highest concentration (0.65 nmol/mg of protein) was observed in cells grown under glucose limitation at pH 7.0 and high dilution rate, and the lowest concentration (0.12 nmol/mg of protein) was found in cells grown under glucose excess at pH 7.0 and high dilution rate. The other general component of the phosphoenolpyruvate:sugar phosphotransferase system, the protein HPr, was not influenced significantly by varying growth conditions.     

Episodic variations of prolactin, thyroid-stimulating hormone, luteinizing hormone, melatonin and cortisol in infertile women with subclinical hypothyroidism

Preliminary data have suggested that female infertility due to corpus luteum insufficiency may be caused by subclinical hypothyroidism [exaggerated thyroid-stimulating hormone (TSH) response to thyrotrophin- releasing hormone (TRH) stimulation]. L-Thyroxine supplementation has been recommended to achieve pregnancies in subclinical hypothyroid women. This controlled study was carried out in order to investigate the biochemical diagnosis of subclinical hypothyroidism as a possible infertility factor. Five infertile patients (aged 25-36 years) with subclinical hypothyroidism (n = 4, stimulated TSH >20 microU/ml) or primary hypothyroidism (n = 1) and five healthy controls (aged 22-39 years) with normal thyroid function (stimulated TSH <15 microU/ml), regular cycles and no history of infertility were studied in the early follicular phase. In the pre-study evaluation, eight of 23 volunteers (34.8%) had to be excluded because of subclinical hypothyroidism with stimulated TSH values (TSHs) >15 microU/ml. Cycle function of patients and controls was compared by the method of LH pulse pattern analysis. Therefore blood samples were drawn every 10 min during a 24 h period. Sleep was recorded from midnight to 7 a.m. Repetition of the TRH tests at the end of the 24 h blood sampling period confirmed the difference in stimulated TSH values of the two study groups. Pulse analysis for luteinizing hormone (LH), TSH and prolactin showed no differences between patients and controls for pulse frequency, amplitude, height, length, area under curve (AUC) and the 24 h mean. Even the hypothyroid patient had a normal LH pulse pattern. Additional measurement of melatonin in pooled sera every 30 min gave the well-documented diurnal profiles during day and night for both groups. Patients had significantly higher melatonin values at seven time points during the night. Peaks for LH, TSH, prolactin and cortisol were correlated with the sleep stages wake, rapid eye movement, 1 + 2 and 3 + 4. We concluded that corpus luteum insufficiency in female infertility cannot be explained by subclinical hypothyroidism and thus should not be treated with L-thyroxine for fertility reasons.