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Biomedical subjects

G De Luca

Publications and source records attributed to G De Luca.

At least 181 records · Page 10Linked to original sources
PubMedDate not supplied

The interaction of haemoglobin, magnesium, organic phosphates and band 3 protein in nucleated and anucleated erythrocytes.

The anion influx was measured in order to study the interaction among organic phosphates, magnesium, haemoglobin and the N-terminal of the cytoplasmic domain of band 3 protein in human, chicken and trout erythrocytes. The rate constant for SO(4)(2-) influx in human and trout erythrocytes increased significantly when it was measured with an increased concentration of intracellular Mg(2+). The SO(4)(2-) influx was also measured in human erythrocyte ghosts in the presence and absence of Mg(2+). The smaller activation provoked by Mg(2+) in ghosts could be caused by the presence of a small quantity of haemoglobin which remained inside. The SO(4)(2-) uptake in chicken erythrocytes in the presence and in absence of Mg(2+) was characterized by very similar rate constants. The results suggest that the small increase in intracellular Mg(2+) in the erythrocytes involves an increase in the formation of Mg(2+)-ATP and Mg(2+)-2,3 BPG complexes reducing the affinity of the organic phosphates for Hb. This new situation may influence the functions of the anion transporter with consequent variations of SO(4)(2-) influx throughout the erythrocyte membrane in human and in trout erythrocytes, whereas in chicken RBCs this function cannot occur and, in fact, no increase in sulphate influx was noticeable. The measurement of Hb/O(2) affinity by the use of alternating fixed and variable concentrations of organic phosphates and Mg(2+), confirms the interactions between these elements and their effect on the mechanism of the affinity. When we measured the sulphate influx in the presence of DIDS we found some differences in the three types of cells.

2,3-Diphosphoglycerate↗
PubMedDate not supplied

Correlation between the effects of retinoic acid and dexamethasone on liver tyrosine aminotransferase.

A single dose of 50 microg of trans-retinoic acid administered to rats significantly raised the level of hepatic tyrosine after a few hours. This effect was compared with that of dexamethasone and a possible correlation between these effectors was also investigated. An equal increase in enzyme activity level caused by retinoic acid was observed in adrenalectomized rats, leading to the suggestion that the effect of retinoic acid on liver tyrosine aminotransferase is independent of glucocorticoids. However, the study of the binding activity of the liver nuclear glucocorticoid receptors vs dexamethasone showed that this activity is favoured by retinoic acid, whereas no variation was evidenced for retinoic acid receptors caused by dexamethasone. In the adrenalectomized rat, the synergistic effect produced by the association of retinoic acid and dexamethasone at the lowest doses used led us to conclude that retinoic acid is an efficient effector of liver tyrosine aminotransferase. It probably affects tyrosine aminotransferase activity in a dependent and an independent way, regulated respectively by the glucorticoid status and by the provision of retinoic acid.

Adrenalectomy↗
PubMedDate not supplied

Reactivity models of 1-N-vinyluracil and synthesis of a new class of potential antiviral agents by the use of 1,3-dipolar cycloaddition reactions.

By the use of a convergent approach based on 1,3-dipolar cycloaddition reactions between N-protected formylnitrones generated in situ and 1-N-vinyluracil, a new class of 4'-aza-analogues of 2',3'-dideoxynucleosides is synthesized. Competitive reaction for the endocyclic bond of uracil also brings to a new isoxazolidine derivative fused with the pyrimidine nucleus.

Antiviral Agents↗
PubMedDate not supplied

Pathophysiology of gastroesophageal reflux and distal esophageal motility in children with gastroesophageal reflux disease.

We investigated the mechanisms of gastroesophageal reflux (GER) and esophageal motility during endogenous esophageal acid exposure in 17 patients with reflux disease alone (age range 3-20 months) (group A) and in 10 patients with reflux disease complicated by esophagitis (age range 4-19 months) (group B), by simultaneous recording distal esophageal sphincter relaxation was the predominant mechanism of reflux in both groups of subjects; however, it was more frequent in group B patients (Bpts), whereas reflux episodes due to appropriate sphincter relaxation were detected more frequently in group A patients (Apts). During endogenous acid exposure, primary peristalsis was the most frequent esophageal motor event in all patients; furthermore, its amplitude was significantly higher in Apts as compared with Bpts. Primary peristalsis was more efficacious (rise of intraluminal pH by at least 0.5 unit) in patients with reflux disease alone, whereas nonspecific motor irregularities were more common in children with reflux esophagitis. It is concluded that the major mechanism of GER in patients with reflux esophagitis is an inappropriate sphincter relaxation; reflux due to appropriate sphincter relaxation is associated with less severe reflux disease; and patients with esophagitis exhibit a deranged esophageal motility during spontaneous acid exposure.

Electromyography↗
PubMedDate not supplied

Effects of short-term high-dose testosterone propionate administration on medium molecular-weight proteins of human seminal plasma.

Effects of short-term high-dose testosterone propionate treatment on medium molecular-weight proteins (lactoferrin, albumin, prostatic acid phosphatase, prostate specific antigen) and on zinc and fructose levels were investigated in the seminal plasma of seven normal volunteers. A significant reduction in levels of prostatic-acid phosphatase, zinc and, to a lesser degree, prostate-specific antigen, lactoferrin and fructose was observed on the 14th day of androgen treatment, concomitantly with the maximal increase in free androgen-circulating levels. The data obtained suggest that testosterone administration may induce a reduction in the sex accessory-gland secretion. Indeed, this effect tends to disappear with withdrawal of hormone treatment. Therefore, the authors suggest a close follow-up of prostatic and vesicular function during the long-term high-dose testosterone intake, used frequently as anabolic treatment by athletes and body builders.

Acid Phosphatase↗
PubMedDate not supplied

Indole-3-pyruvic acid as a possible hypnotic agent in insomniac subjects.

In a single-blind study six male patients (mean age 39.5 years) with moderate insomnia were treated with placebo for three nights, 100 mg indole-3-pyruvic acid (IPA) for three nights, 200 mg IPA for three nights, 100 mg IPA for two nights and placebo for two nights. Polygraphic recordings were made and total sleep time, sleep efficiency, sleep latency, slow wave sleep latency, rapid eye movement (REM) sleep latency, number of arousals (greater than 1 min), percentage and duration of wakefulness after sleep onset, percentage and duration of wakefulness after sleep onset, percentage and duration of sleep stages 1, 2, 3, 4 and REM were recorded. At the end of 13 days, total sleep time, duration of stage 2 sleep and total non-REM were significantly increased when compared with baseline. Total sleep time and duration of stage 2 and total non-REM sleep on completion were significantly decreased when compared with after 200 mg IPA (night 9). Results suggest an action of IPA on human sleep similar to that of exogenous melatonin and L-tryptophan, thus confirming that IPA could be used to increase serotonin and melatonin turnover.

Adult↗