Free radicals are considered to be important factors involved in many physiopathological processes. Several methods have been proposed for studying the mechanisms of antioxidant protection against free radical-induced injury, including the measurement of the total antioxidant capacity (TAC) in body fluids, based on enhanced chemiluminescence. This technique is calibrated against Trolox and assay results are expressed as mumol/L of Trolox equivalents. Since many of the complications induced by diabetes appear to be mediated by oxygen free radical generation, we have investigated serum antioxidant capacity in a group of healthy subjects and in insulin-dependent diabetic (IDDM) subjects. A statistically significant difference was noticed in TAC values between the IDDM group and the young control group. Even if the biological meaning of this significant reduction in TAC remains to be explained, an overproduction of precursors of reactive oxygen free radicals and/or a decreased scavenger systems efficiency can be associated with the increased risk of atherosclerotic cardiovascular disease in diabetic patients.

Adult↗

PubMedDate not supplied

Measurement of seminal LDH-X and transferrin in normal and infertile men.

LDH-X, an isoenzyme of lactate dehydrogenase specific for germinal epithelium activity, has been measured in the seminal plasma of infertile subjects whose infertility had different origins. In the same samples, seminal transferrin, an index of Sertoli cell function, was also measured. In this investigation, seminal LDH-X was not detectable in the vasectomized subjects, in patients with azoospermia due to seminiferous tubular damage, nor in patients who showed a marked decrease in sperm concentration (less than 1 X 10(6)/ml). In oligozoospermic patients (sperm concentration less than 20 X 10(6)/ml) seminal LDH-X levels were reduced to about one-third of those found in normal controls. Seminal LDH-X levels correlated (r = 0.7237) with total sperm count better than seminal transferrin levels (r = 0.5511), while no correlation was found between these two biochemical parameters and sperm motility, viability and morphology. To study their spontaneous variations with time, LDH-X and transferrin were also measured in semen specimens collected monthly from five healthy men, over 1 year. In these samples (N = 60), sperm count variability (43.1%, calculated in terms of the coefficient of variation), was similar to that of LDH-X (40.4%) and higher than for transferrin (23.0%).

Adult↗

PubMedDate not supplied

Simultaneous determination of testosterone, dihydrotestosterone and 5 alpha-androstan-3 alpha,-17 beta-diol by isotopic dilution mass spectrometry in plasma and prostatic tissue of patients affected by benign prostatic hyperplasia. Effects of 3-month treatment with a GnRH analog.

This article reports an isotope dilution mass spectrometric method for the simultaneous measurement of testosterone (T), dihydrotestosterone (DHT), and 5 alpha-androstan-3 alpha, 17 beta-diol (3 alpha-diol) in human plasma and prostatic tissue. After addition of tri-deuterated steroids as internal standards to prostatic tissue homogenates or plasma samples, extraction was performed with diethylether. The extracts were purified by two chromatographic steps (Sep-Pak C 18 cartridge and Sephadex LH-20) and injected into a gas chromatograph coupled with a mass spectrometer after derivatization with heptafluorobutyric acid. This method was highly specific and showed good precision, accuracy, reproducibility and sensitivity. T, DHT, and 3 alpha-diol were measured in human plasma and in prostatic tissue of seven patients with benign prostatic hyperplasia (BPH) treated for 3 months with a long acting GnRH analog before surgery. Plasma levels of T, DHT, and 3 alpha-diol were reduced by GnRH analog treatment to castrate levels. The tissue concentrations of the same steroids, compared with those obtained from 19 untreated patients, showed a mean reduction of about 90% for DHT and 3 alpha-diol, and about 75% for T. These results suggest that about 90% of prostatic DHT and 3 alpha-diol depend on testicular activity because they are dramatically reduced after pharmacologic castration.

Androstane-3,17-diol↗

PubMedDate not supplied

Vasopressin receptors in human seminal vesicles: identification, pharmacologic characterization, and comparison with the vasopressin receptors present in the human kidney.

Because of the presence of a high density of vasopressin receptors in the epithelial cells of porcine seminal vesicles similar to the V2 vasopressin receptors of renal tubules, human seminal vesicles and kidney were investigated using quantitative binding and adenylate cyclase studies. Tissues were obtained at surgery from 17 patients with urologic diseases. A homogeneous class of vasopressin binding sites have been found in both seminal vesicles and renal medulla. However, the vasopressin receptors present in these tissues are different in terms of ligand specificity and adenylate cyclase activation. In seminal vesicles, the V1 vasopressin antagonist d(CH2)5 TyrMeAVP is 36-fold, more potent than the V2 agonist dVDAVP in displacing [3H]AVP binding, while in the medullopapillary portion of kidney dVDAVP is 24-fold, more selective than d(CH2)5 TyrMeAVP for the arginine vasopressin binding site. Furthermore, arginine vasopressin induces a dose-dependent increase in adenylate cyclase activity in renal membranes, while it was ineffective in seminal vesicle membranes. These results indicate that a very high affinity (0.2 nM), low capacity (14 fmoles/mg protein) class of vasopressin receptors is present in human seminal vesicles, having pharmacologic characteristics similar to the V1 subtype of vasopressin receptors. The presence of a high affinity (1.6 nM), high capacity (350 fmoles/mg protein) V2 subtype of vasopressin receptors in human renal membranes is also confirmed. The density of the vasopressin receptors present in human seminal vesicles is inversely correlated with patient age, consistent with a physiologic role for vasopressin in the regulation of accessory sex gland activity.

Adenylyl Cyclases↗

PubMedDate not supplied

Hypoglycemia unawareness in a patient with dumping syndrome: report of a case.

We report the case of a 49-yr-old man affected by coma and hypoglycemia unawareness following repetitive hypoglycemic episodes due to dumping syndrome. The dumping syndrome, which was due to partial gastrectomy and vagotomy performed for recurrent peptic ulcer, was responsible for reactive hyperinsulinemia as demonstrated by an oral glucose tolerance test. While the glucose counterregulatory hormones were all normally sensitive to specific stimulation tests, insulin-induced hypoglycemia failed to induce an adequate counterregulatory response, causing no response in plasma norepinephrine, a slight and short increase in plasma cortisol, ACTH and glucagon and an insufficient increase in plasma epinephrine and GH. This case demonstrates that hypoglycemia unawareness has to be taken into account not only in patients affected by IDDM or insulinoma but also in any case of reactive hypoglycemia.

Adrenocorticotropic Hormone↗

PubMedDate not supplied

5 alpha-reductase deficiency in humans: support to the theory that 5 alpha-reduction of testosterone is an essential step in the control of LH secretion.

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3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗

PubMedDate not supplied

A study on human adrenal secretion. Measurement of epinephrine, norepinephrine, dopamine and cortisol in peripheral and adrenal venous blood under surgical stress.

Epinephrine (E), norepinephrine (NE), dopamine (DA) and cortisol (F) were measured in samples drawn simultaneously by direct venepuncture from the brachial and the adrenal vein of 12 patients undergoing surgery for left kidney diseases. In 7 patients the influence of anesthesia on peripheral plasma levels was also assessed. Catecholamines were measured by a radioenzymatic assay and F by radioimmunoassay. Compared to basal values (mean +/- SE) (E: 53.6 +/- 6.2 pg/ml; NE: 209.4 +/- 24.4 pg/ml; DA: 24.5 +/- 3.3 pg/ml; F: 12.9 +/- 1.2 micrograms/dl) only NE peripheral levels were significantly modified by anesthesia (NE: 343.7 +/- 67.4 pg/ml p less than 0.05), whereas under surgery a significant increase in the peripheral levels was found for every substance measured (mean +/- SE) (E: 332.5 +/- 46.6 pg/ml p less than 0.001; NE: 633.6 +/- 114.2 pg/ml p less than 0.005; DA: 85.8 +/- 15.7 pg/ml p less than 0.005; F: 21.3 +/- 1.9 micrograms/dl p less than 0.01). Catecholamine and F levels in adrenal vein showed a high variability suggesting an intermittent secretion. In the adrenal venous blood E levels were, in the mean, 381 times higher, NE levels 45 times, DA levels 27 times and F levels 23 times higher than in peripheral blood. E, NE and DA concentrations in the adrenal vein were all significantly correlated to the others but not to cortisol, suggesting that the medulla secrets E, NE and DA in rather constant ratios and that the cortex and the medulla respond differently to surgical stress.

Adrenal Glands↗

PubMedDate not supplied

Isolation and characterization by conventional methods and genetic transformation of Psychrobacter and Acinetobacter from fresh and spoiled meat, milk and cheese.

Of 126 samples of fresh and spoiled meat and dairy products, 40% were positive for the presence of Moraxella-like bacteria and 64% of Acinetobacter; 279 and 466 strains, respectively, were isolated and a part of these were tested by biochemical methods and DNA transformation assays. In some cases, the Moraxellaceae in the samples examined reached considerable quantitative levels, but their percentage in the microflora was generally low. Moraxella-like bacteria were predominant in fresh meat, Acinetobacter in spoiled meat and milk. Most acinetobacters belonged to biotype lwoffii (sensu lato) and all 90 strains tested were positive for DNA transformation with an auxotrophic Acinetobacter. Moraxella-like bacteria were identified as Psychrobacter immobilis in 96% of 103 transformation assays. Moraxellaceae show lipolytic activity but they are considered of low incidence in food spoilage. Only 3.7% of acinetobacters from dairy sources was able to produce ropy milk. Unlike strains from clinical isolates, psychrobacters and acinetobacters isolated from food often do not grow at 37 degrees C.

Acinetobacter↗

PubMedDate not supplied

Vasodilatation induced by capsaicin in rat mesenteric vessels is probably independent of nitric oxide synthesis.

Vasal relaxation induced by capsaicin was investigated on perfused mesenteric vascular bed prepared from Wistar rats. Bolus infusion of capsaicin, from 3.5 to 16 nmol, elicited a dose-dependent vasal relaxation effect, which was antagonized by pretreatment with 3 x 10(-6) M calcitonin gene-related peptide (CGRP) (8-37), an antagonist of CGRP. In order to test whether NO-release is involved in vasorelaxant response to capsaicin, a preparation of mesenteric vascular bed was perfused and superfused for 1 h by N omega-nitro-L-arginine methyl ester (L-NAME) (3 x 10(-3) M), an NO-synthase inhibitor. Vasodilatation induced by capsaicin remained unchanged, while that induced by acetylcholine, used as control, was significantly reduced. The results indicate that in the mesenteric bed, capsaicin-induced vasodilatation is probably independent of the NO-synthesis mechanism and possibly mediated by CGRP.

Amino Acid Oxidoreductases↗