Testosterone concentration in different functional compartments of the male reproductive tract.

The concentration of testosterone in testicular tissue (TT), spermatic vein blood (SVB), cubital blood (CB), and seminal fluid (SF) was estimated using a radioimmunoassay technique in a total of 50 normospermic, oligozoospermic, and azoospermic men. Testosterone was also determined in cauda epididymis-vas deferens ductus wash fluid (WF) in 6 normospermic men. In 2 oligozoospermic men the testosterone concentration in TT was 556 and 725 ng/g tissue, respectively. In 9 normospermic men the mean SVB testosterone concentration was 473 ng/ml. CB and SF concentrations of this steroid were 6.8 and 0.4 ng/ml in normospermic, 6.4 and 0.5 ng/ml in oligozoospermic, and 4.9 and 0.4 ng/ml in azoospermic men, respectively; the difference among the three groups was not significant. The SVB:CB and SVB:SF ratios in normospermic men were 71 and 1549, respectively, while the CB:SF ratio was 18 in normospermic, 18 in oligozoospermic, and 16.6 in azoospermic men. Testosterone could not be detected in individual specimens of WF, but after pooling of samples a concentration of 0.08 ng/ml WF was estimated. These results demonstrate the relative concentrations of testosterone in the different functional compartments of the reproductive tract in man and facilitate a better understanding of its function.     

The effect of energy intake and expenditure on the recovery of 13CO2 in the parenterally fed neonate during a 4-hour primed constant infusion of NAH13CO3

The use of 13CO2 excretion to measure the oxidation of 13CO2 labeled substrates is increasing as it is both noninvasive and lacks the radiation exposure associated with the use of 14C. No standards are available for 13CO2 recovery in breath from the bicarbonate pool in the neonate. A primed constant infusion of NaH13CO3 over 4 h was used with open circuit indirect calorimetry in 15 appropriate for gestational age newborn infants (gestational age 28-39 wk; postnatal age 2-52 days), on varying amounts of intravenous feeding (37-114 kcal X kg-1 X day-1). Following a bolus of 6.9 mumol X kg-1 of NaH13CO3, a maintenance infusion of 4.6 mumol X kg-1 X h-1 was started. The 13C enrichment in breath rose rapidly to reach a plateau by 90 min with less than 5% variation of the plateau. Recovery of the tracer in breath ranged from 69.6-83.5% and was significantly correlated with 1) energy intake (37-114 kcal X kg-1 X day-1); 2) metabolic rate (34.6-56.1 kcal X kg-1 X day-1); 3) VCO2 (4.86-7.43 ml X kg X -1 X min-1). There was no correlation with the level of protein or fat intake. We provide an equation that can be used to calculate the correction factor when doing constant infusion substrate oxidation studies with a 13C label in neonates.     

Expression of specific granule markers on the cell surface of neutrophil cytoplasts

The widespread assumption that cytoplasts generated from human polymorphonuclear leukocytes (PMNs) are vesicles consisting solely of cytoplasm surrounded by plasma membrane and devoid of granule activity remains to be tested. PMN cytoplasts were prepared by centrifugation of intact cells on a Ficoll step gradient in the presence of cytochalasin B. Two granule membrane markers, Mol, a fluorometrically detectable antigen, and cytochrome b, both of which have been shown to translocate to the plasma membrane during granule release, were compared for their activity in cytoplasts and intact PMNs. We found that the amount of Mol detected on the plasma membrane of intact PMNs, as compared with other membrane markers (such as antigens LFA-1 and beta 2m), increased 1.6- fold upon exposure of PMNs to Ficoll plus cytochalasin B prior to centrifugation. Another twofold increase in Mol expression occurred upon cytoplast preparation. Release of the granule enzymes, vitamin B12- binding protein, and lysozyme were also followed and correlated well (r = .78 and .92) with the amount of Mol antigen present on the cell surface. Cytochrome b was also found to be higher (1.4-fold) on plasma membranes isolated from cytoplasts than on plasma membranes isolated from intact control cells. These results indicate that some fusion of granule membranes and plasma membranes occurred during treatment of PMNs with Ficoll plus cytochalasin b and during cytoplast preparation.