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Biomedical subjects

A Oradei

Publications and source records attributed to A Oradei.

27 records · Page 2Linked to original sources
PubMed1988

Differential effects of feeding on the ultradian variation of the growth hormone (GH) response to GH-releasing hormone in normal subjects and patients with obesity and anorexia nervosa.

Nutritional status and metabolic fuels are factors involved in the regulation of GH secretion and GH responses to GHRH. The effects of feeding on GHRH-induced GH release were studied in 13 normal women, 14 obese women, and 9 women with anorexia nervosa. GHRH-(1-44) (50 micrograms, iv) was administered at 0900 h after an overnight fast or at 1300 h after a normal meal at 0800 h, and at the same times 45 min after a 800-Cal meal on different days. The mean peak plasma GH responses to GHRH administered before a meal at 0900 h were 52.8 +/- 5.6 (+/- SE) micrograms/L in normal women, 8.2 +/- 1.3 micrograms/L in obese women, and 53.2 +/- 7.7 micrograms/L in anorexic women. When GHRH was administered before a meal at 1300 h, the mean peak plasma GH levels were lower than those at 0900 h; this reduction was -64.2% in normal women, -64.9% in obese women, and -55.8% in women with anorexia nervosa. After feeding, the plasma GH responses to GHRH were blunted in normal women at 0900 h (-60.9%) and 1300 h (-34.6%) compared with the fasting peak responses. In obese women the plasma GH response to GHRH after feeding was increased compared with that when these women had fasted (+60% at 0900 h and +406.9% at 1300 h). Finally, differential effects of feeding were present in anorexic women; the response was lower at 0900 h (-46.4%) and greater at 1300 h (+50.8%). We conclude that there is an ultradian variation in GHRH-stimulated GH secretion and that the responses differ according to nutritional status and body weight.

Adult↗
PubMed1985

In vitro effect of different ubiquinones on the scavenging of biologically generated O2-.

The ability of different homologues of Coenzyme Q to quench O2- was tested in vitro with three experimental systems known to generate O2-. Two of them were biological generators, namely the xanthine-xanthine oxidase system and the cyanide-insensitive NADPH oxidase of polymorphonuclear leucocytes. The third was a chemical generator of O2-, the NADH-phenazine methosulphate-nitroblue tetrazolium mixture. Short-side-chain ubiquinones were found to be the most potent scavengers of O2-, being effective at concentrations as low as 10(-7) M. This finding might be ascribed to the relatively greater water-solubility of the lower homologues of CoQ. We postulate that CoQ10 may well exert such an O2- -scavenging mechanisms in vivo where it is inserted in its natural phospholipid environment.

Humans↗
PubMed1984

Quenching of singlet oxygen by D-alpha-tocopherol in human granulocytes.

The ability of D-alpha-tocopherol to act as a quencher of (1)0(2) (singlet oxygen) was tested with a biological source of (1)0(2), namely the phagocytosis activated myeloperoxidase contained in the homogenate of human circulating polymorphonuclear leukocytes. With this system, the (1)0(2) quenching efficiency of exogenously added D-alpha-tocopherol was estimated from its inhibitory effect on the luminol amplified chemiluminescence. This inhibitory effect was dose dependent. D-alpha-tocopherol was also efficient in quenching the chemiluminescence generated through the H2O2-horseradish system. In both systems the quenching effect may be almost entirely "physical", since very little tocopherol was destroyed when compared to the relatively large amount of H2O2 consumed.

Humans↗
PubMedDate not supplied

Coenzyme Q10 in pregnancy.

Our objectives were to assess the plasma coenzyme Q10 (CoQ10) levels in normal pregnancy, in pregnancy with a spontaneous contractile event, in spontaneous abortion and in threatened abortion. Six hundred and fifteen CoQ10 levels were analyzed in 483 pregnant women: 350 patients were employed to design a normal curve; 66 patients with spontaneous contractile activity underwent two or more CoQ10 analyses in different trimesters; 49 patients presented spontaneous abortion, and 18 patients threatened abortion. The normal curve of plasma CoQ10 levels rises during each trimester of pregnancy, while there is a correspondence between a low CoQ10 level and spontaneous abortion. Furthermore we found a statistically significant difference between the plasma CoQ10 value in spontaneous contractile activity, mainly in the third trimester. We found an increase in the plasma CoQ10 level in relation to the contractile activity of the uterine muscle. Further studies are necessary to explain the involvement of this marker on pregnancy in clinical practice.

Abortion, Spontaneous↗
PubMedDate not supplied

Acetylcholinesterase inhibition by eserine: rate constants of reaction. Part II.

The inhibition of eel acetylcholinesterase by physostigmine at 20 degrees and 25 degrees C have been investigated. In our evaluation the unimolecular reactivation rate constant, k3, the carbamylation rate constant, k2, and the binding constant, Ka, are the first simultaneously determined. The mechanism of this reaction is discussed.

Animals↗
PubMedDate not supplied

A new simple method for determining the kinetic constants of inhibited acetylcholinesterase.

The authors, with a spectrophotometric procedure, have evaluated the kinetic constants of physostigmine, a cholinesterase inhibitor which assumes an important function when the degeneration of cholinergic projections is observed. This approach overcomes some of the difficulties encountered in measuring the binding and the carbamylation rate constants. A kinetic treatment, consistent with the experimental results observed in the enzyme-inhibitor system in the presence of substrate, is developed.

Acetylcholinesterase↗
PubMedDate not supplied

Coenzyme Q10 concentrations in normal and pathological human seminal fluid.

Coenzyme Q10 (CoQ10) levels were assayed in total seminal fluid or both in seminal fluid and seminal plasma in 77 subjects with normal or pathological findings at standard semen analysis. CoQ10 levels showed a significant correlation with sperm count and with sperm motility. An interesting exception was constituted by patients with varicocele, in whom the correlation with sperm concentration was preserved, whereas the correlation with sperm motility was lacking. Moreover, they showed an increased ratio of plasma CoQ to total seminal CoQ10 in comparison with the other subjects. These data suggest a pathophysiological meaning of CoQ10 in human seminal fluid and a possible molecular defect in varicocele patients. CoQ10 measurement could represent an important examination in infertile patients; moreover, from these results a rationale might arise for a possible treatment with exogenous CoQ10 in dyspermic patients.

Adult↗