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Biomedical subjects

G Forti

Publications and source records attributed to G Forti.

At least 145 records · Page 8Linked to original sources
PubMed1983

Effects of pharmacological doses of testosterone and dihydrotestosterone on the hypothalamic-pituitary axis function of Klinefelter patients.

Six patients affected by Klinefelter's syndrome (KS) were treated with testosterone propionate (TP) 100 mg im daily for 4 days and one month later the same patients received dihydrotestosterone propionate (DHTP) 100 mg im daily for 4 days. Plasma levels of LH, FSH, PRL, testosterone (T) and dihydrotestosterone (DHT) have been measured in these patients for 8 days during and after TP and DHTP treatment. TP administration reduced LH levels only transiently, while a more prolonged reduction was observed for FSH. DHTP administration produced a late and transient reduction of LH and a very late reduction of FSH. PRL levels increased significantly during and after TP administration. Our data suggest that in Klinefelter patients: i) DHT is less effective than T in suppressing gonadotropin concentrations, ii) the increased PRL levels observed during and after TP administration are not due to a pure androgenic effect, but are probably related to an increased conversion rate of T to estradiol.

Adolescent↗
PubMed1983

Interaction of ferredoxin and ferredoxin-NADP reductase with thylakoids.

Ferredoxin-NADP reductase accounts for about 50% of the NADPH diaphorase activity of spinach leaf homogenates. The enzyme is bound to thylakoid membranes, but can be slowly extracted by aqueous buffers. Ferredoxin-NADP reductase can be extracted from the membranes by a 1- to 2-min treatment with a low concentration of trypsin. This treatment completely inactivates NADP photoreduction but does not affect electron transport from water to ferredoxin. It is shown that the inactivation is due to solubilization of ferredoxin-NADP reductase: the activity can be restored by addition of a very large excess of soluble enzyme in pure form. When ferredoxin-NADP reductase is added as a soluble enzyme after extraction or inactivation (by a specific antibody) of the membrane-bound enzyme, NADP photoreduction requires a very large excess of this enzyme, and the apparent Km for ferredoxin is also increased. These observations are discussed as related to the interactions of thylakoids with ferredoxin-NADP reductase.

Chloroplasts↗
PubMed1983

Steroid secretion by the prepubertal human testis.

It has been demonstrated that the human testis secretes testosterone and, to a smaller extent and less constantly, also androstenedione. Testosterone, progesterone, 17 alpha-hydroxyprogesterone and 20 alpha-dihydroprogesterone have been measured in the spermatic and peripheral venous blood of prepubertal boys undergoing surgery for undescended testis or inguinal hernia repair. The spermatic plasma levels of testosterone and progesterone were significantly higher than peripheral levels. A significant spermatic-peripheral gradient was not found for 17 alpha-hydroxyprogesterone and 20 alpha-dihydroprogesterone. These studies demonstrate that the secretory pattern of the human prepubertal testis is different from that of the adults.

Androgens↗
PubMed1983

Spermatic and peripheral venous plasma concentrations of dehydroepiandrosterone sulfate in prepubertal and pubertal boys.

Dehydroepiandrosterone sulfate (DEAS), a major adrenal product, is quantitatively one of the most important steroids found in human testicular tissue. However, conflicting data have been reported about the testicular production of DEAS 'in vivo'. We have measured the spermatic and peripheral concentrations of testosterone (T) and DEAS in two groups of prepubertal (Group I, N = 18) and pubertal (Group II; N = 11) boys undergoing surgery for undescended testis, inguinal hernia or varicocele. Mean (+/- SE) spermatic concentrations of DEAS (77 +/- 16 and 113 +/- 19 micrograms/dl in Group I and II respectively) were not significantly different from peripheral concentrations (70 +/- 13 and 130 +/- 16 micrograms/dl in Group I and II respectively). Mean spermatic concentrations of T (153 +/- 101 and 7515 +/- 4314 ng/dl in Group I and II respectively) were significantly different from peripheral concentrations (9 +/- 1 and 149 +/- 53 ng/dl; P less than 0.001 in both groups). Spermatic and peripheral levels of T and DEAS found in prepubertal boys were significantly lower than those found in pubertal boys. Spermatic levels of DEAS were not significantly related with spermatic levels of T in both groups. Our data show that, as in adult subjects, no significant spermatic-peripheral DEAS gradient is present in prepubertal and pubertal boys.

Adolescent↗
PubMed1983

Effects of surgery and epidural or general anaesthesia on testosterone, 17-hydroxyprogesterone and cortisol plasma levels in prepubertal boys.

Testosterone (T), 17-hydroxyprogesterone (17P) and cortisol (F) plasma levels have been measured in two groups of prepubertal boys before and during surgery under general anaesthesia (Group 1) and epidural anaesthesia (Group 2) respectively. The mean plasma levels of T, 17P and F increased significantly (P less than 0.05; P less than 0.001; P less than 0.005, respectively) during surgery in Group 1; in Group 2 the plasma levels of T and F did not show any significant variation, whereas 17P significantly increased (P less than 0.05). However the mean level reached by 17P in Group 2 was significantly lower (P less than 0.005) than that observed in Group 1. No significant variation of LH and FSH plasma levels was observed in either group. Our report suggests that the modifications of T and 17P plasma levels observed during surgery under general anaesthesia (GA) are probably due to the stress induced adrenal response. This response can be inhibited or reduced by epidural anaesthesia (EA).

17-alpha-Hydroxyprogesterone↗
PubMed1983

Spermatic and peripheral venous plasma concentrations of progesterone, 17 alpha-hydroxyprogesterone, and 20 alpha-dihydroprogesterone in prepubertal boys.

Testosterone, progesterone, 17 alpha-hydroxyprogesterone, and 20 alpha-dihydroprogesterone have been measured in the spermatic and peripheral venous blood of 17 prepubertal boys undergoing surgery for undescended testis or inguinal hernia repair. Mean (+/-SE) spermatic testosterone and progesterone (538 +/- 212 and 704 +/- 110 pg/ml, respectively) were significantly higher (P less than 0.005) than peripheral levels (91 +/- 11 and 419 +/- 71 pg/ml, respectively). No significant spermatic-peripheral gradient was found for 17 alpha-hydroxyprogesterone and 20 alpha-dihydroprogesterone. These in vivo studies demonstrate that the secretory pattern of the prepubertal testis is different from the adult testis.

20-alpha-Dihydroprogesterone↗
PubMed1981

Effects of trypsin and cations on chloroplast membranes.

A mild tryptic digestion of chloroplast membranes eliminates the effects of saturating concentrations of cations (3 to 5 millimolar MgCl(2)) on chlorophyll fluorescence yield, membrane stacking, and photosystem II photochemical efficiency in spinach. At the same time, the negative surface potential of the membranes is increased (by trypsin) as revealed by studies with 9-aminoacridine. High concentrations of cations (25 to 100 millimolar MgCl(2)) added after trypsin digestion are effective in restoring high fluorescence yields and membrane stacking. High concentrations of cations added after trypsin treatment do not increase the photosystem II efficiency. It is concluded that the "diffuse electrical layer" hypothesis of Barber et al. (Barber J, J Mills, A Love, 1977 FEBS Lett 74: 174-181) satisfactorily explains the effect of trypsin in eliminating the influence of saturating concentrations of cations on chlorophyll fluorescence yield and membrane stacking. However, the effect on photosystem II photochemical efficiency seems to require another mechanism.

Journal Article↗
PubMed1981

Testosterone concentrations in spermatic venous blood plasma of prepubertal boys.

Testosterone concentration has been measured in spermatic and peripheral venous plasma obtained during surgery from a total of 25 prepubertal boys affected either by inguinal hernia (Group I; N = 6; age range 2-8 years) or unilateral undescended testis (Group II; N = 19; age range 5-11 years). Median spermatic venous testosterone level was 58.7 ng/dl) (range 14.0--120.8 ng/dl) in Group I and 43.2 ng/dl (range 12..2-267.5 ng/dl) in Group II; median peripheral testosterone level was 4.9 ng/dl (range 2.3-15.4 ng/dl) and 5.6 ng/dl (range 1.1-89.3 ng/dl) in Group I and II, respectively. The difference between the spermatic and peripheral level was statistically significant in both groups (P less than 0.01 in Group I and P less than 0.001 in Group II). These results indicate that the prepubertal human testis secretes testosterone, even if in a very low amount. It is also suggested that this secretion can be responsible for LH inhibition in prepubertal boys.

Child↗
PubMed1981

Spermatic and peripheral oestradiol levels in patients affected by azoospermia due to seminiferous tubular damage.

Plasma levels of testosterone, androstenedione and oestradiol were determined in the spermatic venous blood of both testes of 17 patient affected by azoospermia due to tubular damage (Group I). The results were compared with those found in 5 patients affected by azoospermia of obstructive origin and 5 patients with an inguinal hernia (Group II). Mean spermatic levels of testosterone and androstenedione were not significantly different in the two groups, while the mean (+/- SE) oestradiol spermatic level was significantly higher in patients of Group I (5.02 +/- 0.75 nM/l vs. 2.20 +/- 0.365 nM/l; P less than 0.05). Moreover, while the testosterone/androstenedione and the androstenedione/oestradiol ratios were not significantly different in the two groups, the mean (+/- SE) testosterone/oestradiol ratio was significantly lower in patients of Group I (552.71 +/- 80.94 vs. 939.86 +/- 129.45; P less than 0.025). Peripheral testosterone and androstenedione mean levels were not significantly different between the two groups while the mean peripheral oestradiol level (+/- SE) was significantly higher in Group I (0.107 +/- 0.021 nM/l vs. 0.038 +/- 0.05 nM/l; P less than 0.025). Peripheral oestradiol was not significantly related to peripheral FSH, nor to spermatic oestradiol in both groups. These results suggest the possibility that oestradiol may be involved in the pathogenesis of some cases of male infertility.

Adult↗
PubMed1981

Spermatic and peripheral plasma concentrations of testosterone and androstenedione in prepubertal boys.

Spermatic and peripheral plasma concentrations of testosterone (T) and androstenedione (A) have been measured in prepubertal boys affected by inguinal hernia (group I; n = 7) and unilateral undescended testis (group II; n = 18). Mean (+/- SE) spermatic T concentrations (47.7 +/- 14.8 ng/dl in group I; 36.3 +/- 3.4 ng/dl in group II) were significantly different from mean peripheral T concentrations (9.8 +/- 2.1 ng/dl in group I; 9.3 +/- 0.9 ng/dl in group II) in both groups (P less than 0.05 and P less than 0.0005, respectively). Mean spermatic A concentration (59.7 +/- 4.9 ng/dl) was significantly higher than mean peripheral A concentration (49.8 +/- 4.9 ng/dl) in group II (P less than 0.05) but not in group I. Mean spermatic and peripheral T and A values found in boys of group I were not significantly different from those found in group II. The mean spermatic/peripheral T ratio was higher (5.01 in group I; 4.42 in group II) than the corresponding mean spermatic/peripheral A ratio (1.27 in group I; 1.32 in group II) in both groups. Our data suggest that 1) although testicular T secretion is present in all prepubertal boys, A secretion is not constant and often negligible; 2) the contribution of testicular secretion to the circulating T is much more important than the contribution to the circulating A; 3) no significant differences were found between the testicular secretory pattern of prepubertal boys with inguinal hernia and unselected boys with unilateral undescended testis.

Androstenedione↗
PubMed1980

Plasma dehydroepiandrosterone sulphate in hypothyroid premenopausal women.

Plasma dehydroepiandrosterone sulphate (DHEAS), cortisol (F) and prolactin (PRL) were measured in seventeen premenopausal women with primary hypothyroidism and in fifteen normal premenopausal women. Significantly lower (P < 0.001) DHEAS levels were found in hypothyroid women while F and PRL were in the range of normal controls. No significant relation was found between DHEAS and total thyroxine (T4) and TSH. Our results support the hypothesis that DHEAS secretion is impaired in some women with primary hypothyroidism.

Adult↗
PubMed1980

Functional renal alterations in chronic liver diseases.

83 patients with chronic active hepatitis (CAH), 38 of them with cirrhosis, were studied and compared with 10 control subjects suffering from chronic persistent hepatitis (CPH). Tubular acidosis frequently was found in our cases. Renal plasma flow and glomerular filtration rate were significantly decreased in CAH when compared with CPH. Selective renal arteriography showed evident decrease of arterial flow in the outer cortex. Selective renal scan with 99mTc microspheres of human albumin showed a frequent escape of the tracer from the kidney to the lung. PGE1 and PGE2 levels appeared higher in the renal artery than in the vein and were significantly more elevated in 9 cases with cirrhosis vs. 13 controls. These results suggest the frequent functional impairment of the kidney also in the early stages of CAH, with an increase of PGE levels and an opening of intrarenal shunts.

Acidosis, Renal Tubular↗
PubMed1979

Evidence for a structural role for chlorophyll in chlorophyll-protein complexes.

1. Chymotrypsin treatment of spinach chloroplast membranes does not change the electrophoretic mobility of either chlorophyll-protein complex 1 or 2. 2. The extraction of lipids with 80% acetone after treatment of the membranes with chymotrypsin reveals that the polypeptide components of both chlorophyll-protein complexes had been extensively digested. The extraction of carotenes with petroleum ether under the same conditions does not change the electrophoretic mobility of the chlorophyll-protein complexes. 3. Fluorescence polarisation studies of chlorophyll-protein complex 2 reveal that the chymotrypsin digestion of this complex does not result in changes of mutual orientation or distance apart of chlorophyll a, chlorophyll b or carotenoid. 4. Two polypeptide components have been detected after lipid extraction of electrophoretically purified chlorophyll-protein complexes 1 and 2. The SDS molecular weights are 24 000 and 27 000 for complex 2, and 68 000 and 64 000 for complex 1. 5. We conclude that chlorophyll performs an important structural function in both chlorophyll-protein complexes.

Chlorophyll↗
PubMed1979

Partition zone penetration by chymotrypsin, and the localization of the chloroplast flavoprotein and photosystem II.

1. Chymotrypsin treatment of chloroplast membranes inactivates Photosystem II. The inactivation is higher when the activity is measured under low intensity actinic light, suggesting that primary photochemistry is preferentially inactivated. 2. Membrane stacking induced by Mg2+ protects Photosystem II against chymotrypsin inactivation. When the membranes are irreversible unstacked by brief treatment with trypsin, Mg2+ protection against chymotrypsin inactivation of Photosystem II is abolished. 3. The kinetics of inactivation by chymotrypsin of Photosystem II indicates that membrane stacking slows down, but does not prevent, the access of chymotrypsin to Photosystem II, which is mostly located within the partition zones. 4. It is concluded that a partition gap exists between stacked membranes of about 45 A, the size of the chymotrypsin molecule. 5. The kinetics of inhibition of the chloroplast flavoprotein, ferredoxin-NADP reductase, bt its specific antibody is not affected by membrane stacking. This indicates that this enzyme is located outside the partition zones.

Chloroplasts↗
PubMed1979

Seminal plasma levels of testosterone and 5 alpha-dihydrotestosterone in azoospermic patients.

Testosterone (T) and 5 alpha-dihydrotestosterone (DHT) have been measured in seminal plasma of sixteen azoospermic patients with tubular damage (germinal cell arrest or Sertoli cell only syndrome) and five patients affected by azoospermia of obstructive origin. In both groups T values were not significantly different from controls, while DHT was significantly lower in patients affected by azoospermia of obstructive origin.

Dihydrotestosterone↗
PubMed1978

Klinefelter's syndrome: a study of its hormonal plasma pattern.

Plasma testosterone (T), dihydrotestosterone (DHT), 17 beta-estradiol (E2), 17-hydroxyprogesterone (17-OHP), androstenedione (delta), dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulphate (DHEAS), 5-androstene-3 beta-17 beta-diol (A-diol) and cortisol (F) have been measured in a group of normal males and in a group of patients with Klinefelter's syndrome (KS) before and after hCG stimulation. Significantly lower baseline levels of T and DHT and significantly higher baseline levels of E2 were found in patients with KS. No significant differences were found between baseline levels of 17-OHP, delta, DHEA, DHEAS, A-diol, and F. After hCG stimulation between T, DHT, E2 and 17-OHP levels showed a significant increase in the two groups of subjects. The percentage variation of T and DHT, however, was much less important in Klinefeiter patients, while E2 and 17-OHP did not show a significantly different pattern from that of normal controls, hCG administration did not produce any significant variation of delta, DHEA, DHEAS, and F in the two groups of subjects, while A-diol levels increased significantly in normal subjects, but not in Klinefelter patients. Our data may be consistent with the hypothesis that testicular steroidogenesis in Klinefelter patients is impaired below the 21-C-steriod level not only at delta 4 but also at the delta 5 pathway.

Adolescent↗