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A Renzetti

Publications and source records attributed to A Renzetti.

13 recordsLinked to original sources
PubMed1996

Rat astroglial P2Z (P2X7) receptors regulate intracellular calcium and purine release.

Treatment of rat astrocyte cultures with 2'- and 3'-O-(4-benzoylbenzoyl)-adenosine 5'-triphosphate (BzATP), a P2X7 agonist, but not with adenosine 5-[alpha, beta methylene] triphosphate (alpha, beta meATP), a P2X agonist, increased influx of extracellular Ca2+ and [Ca2+]i. Lucifer yellow, a small molecule which permeates P2X7 receptor-induced pores, entered BzATP-treated but not control astrocytes. BzATP also stimulated efflux of [3H]purine from cultured astrocytes. The P2X7 receptor antagonist oxidized ATP abolished the effects of BzATP on [Ca2+]i, lucifer yellow permeation and [3H]purine release, indicating that these effects were due to P2X7 receptor activation. In neurological diseases or injuries extracellular ATP may activate P2X7 receptors further enhancing [3H]purine release, with important pathophysiological consequences.

Animals↗
PubMed1996

Sex steroid modulation of AT2 receptors in human myometrium.

In contrast to the abundant expression of the AT2 subtype of angiotensin II (AII) receptors during fetal development, AT2 receptor in adult life is expressed in few tissues. We now report studies on the presence and hormonal regulation of AT2 receptor in human pregnant and nonpregnant myometrium obtained from a large study population (n = 50). AT2 receptor subtypes have been characterized using self- and cross-competition curves among [125I]CGP42112A (a selective AT2 ligand), [125I](Sar1,Ile8)AII (a unselective antagonist), the corresponding unlabeled ligands, and several peptidic and nonpeptidic analogs with different affinities for the AT1 and AT2 receptor subtypes. We found that the human nonpregnant uterus expresses almost exclusively the AT2 subtype, and that [125I]CGP42112A is a selective probe to study human AT2 receptor. By using [125I]CGP42112A, we demonstrated that the density of AT2 receptor in human myometrium is dramatically affected by the hormonal milieu. Indeed, in the estrogen-dominant uterus of normal cycling women in the proliferative phase and that of perimenopausal women with anovulatory cycles, the density of binding sites was very high [1565 +/- 246 fmol/mg protein (n = 11) and 2176 +/- 429 (n = 7), respectively]. The concomitant presence of progestogens blunted the estrogen effect [term pregnancy, 61 +/- 12 fmol/mg protein (n = 5); secretive phase of the cycle, 453 +/- 154 (n = 10); combined oral contraceptive, 243 +/- 74 fmol/mg protein (n = 6)]. Very low concentrations of binding sites are also present in the sex steroid-deprived uterus of postmenopausal women (100 +/- 12 fmol/mg protein; n = 8) and the uterus of fertile women chronically treated with GnRH agonists (199 +/- 100 fmol/mg protein; n = 3). Hence, these data confirm the presence of AT2 receptors in human uterus and indicate their regulation by sex steroids.

1-Sarcosine-8-Isoleucine Angiotensin II↗
PubMed1990

Insulin supplement in type 2 diabetic patients with secondary failure to oral agents ameliorates hepatic and peripheral insulin sensitivity but not insulin secretion.

In order to investigate the mechanism of amelioration of metabolic abnormalities with supplementary doses of insulin, islet B-cell function and insulin sensitivity were measured in 10 patients with Type 2 diabetes in secondary failure to oral agents. A small dose of ultralente insulin (0.26 +/- 0.07 U kg-ideal-body-weight-1) was added in the morning before breakfast. After 3 months insulin therapy and progressive improvement of metabolic control (HbA1 from 10.5 +/- 0.4 to 9.0 +/- 0.3% at the end of insulin treatment, p less than 0.001), basal C-peptide and incremental area during an oral glucose tolerance test were unchanged. In vivo peripheral insulin sensitivity (euglycaemic clamp with insulin infusion of 40, 160, and 600 mU m-2 min-1, respectively) was significantly improved (glucose requirement: to 4.7 +/- 1.0 from 3.0 +/- 0.6 mg kg-1 min-1, p less than 0.05 at first insulin level; to 10.8 +/- 0.5 from 9.3 +/- 0.7 mg kg-1 min-1, p less than 0.01 at second level; to 13.3 +/- 0.6 from 11.8 +/- 0.8 mg kg-1 min-1, p less than 0.025 at third level). Basal hepatic glucose production was also significantly reduced (from 4.3 +/- 0.4 to 3.3 +/- 0.3 mg kg-1 min-1, p less than 0.05), and residual glucose production further suppressed after insulin supplement (from 1.1 +/- 0.4 to 0.3 +/- 0.2 mg kg-1 min-1 after 120 min at 100 mU l-1 plasma insulin, p less than 0.05). Specific insulin binding to mononuclear leucocytes was unchanged (from 3.1 +/- 0.3 to 3.5 +/- 0.3%, NS).

C-Peptide↗
PubMed1984

Relationship between the 210Pb content of teeth and exposure to Rn and Rn daughters.

Existing data on 210Pb in human teeth are reviewed for various countries. The mean value of 210Pb in the teeth of population groups exposed to "normal" levels of radon-daughter exposure is about 2 mBq/g. A detailed analysis of 48 samples from a "normal" Italian population group revealed that smoking habits and age may have some influence on 210Pb content of teeth, while this is not the case for differences in sex. A group of 45 Austrians exposed to elevated levels of radon and radon daughters is compared with the Italian group. After subtraction of background levels of 210Pb as found for the normal Italian population, the incremental 210Pb tooth content due to excessive radon-daughter exposure has been correlated with the individual cumulative exposure corrected for background radon-daughter exposure. A statistical analysis shows the significance of the linear correlation at the alpha = 0.01 level. For the incremental increase of 210Pb in teeth, a value of 1.2 mBq/g has been used for a lifetime exposure to 1 WLM. This result is compared to corresponding data published in the literature, which are predominantly related to the 210Pb content of bone after short-time exposure at high levels, e.g. in uranium mines. The comparison seems to indicate the influence of the exposure rate and the need for a comprehensive model, which takes into account radon-daughter inhalation, radon dissolved in body fluids and 210Pb metabolism.

Adolescent↗
PubMed1976

Interactions between viruses and bacteria in patients with chronic bronchitis.

The possibility that viral infections of the respiratory tract might predispose to bacterial colonization or infection was studied in 120 patients with chronic obstructive pulmonary disease and 30 control subjects; these individuals were observed for seven years. The ratio of the number of observed to the number of expected associations between viruses and bacteria was 2.43 (P = 0.037) for the pair influenza virus and Streptococcus pneumoniae and was 2.06 (P = 0.056) for influenza virus and Haemophilus influenzae. Consistently positive, but not significant, associations were detected between rhinovirus and herpes simplex virus infections and isolations of S. pneumoniae and H. influenzae. In contrast, isolations of the nonpathogenic Haemophilus parainfluenzae could not be related to prior viral infections. Significant rises in titer of antibody to H. influenzae were detected on 76 occasions, and 20 (26%) of these antibody rises were associated with viral or mycoplasmal infections during the preceding 120 days. The expected number of such associations was 8.34 (ratio of number observed to number expected, 2.40; P = 0.08). These results suggest that viral infections of the respiratory tract in patients with chronic obstructive pulmonary disease are associated with increased colonization by potentially pathogenic bacteria and may also predispose to infections with H. influenzae.

Antibodies, Bacterial↗
PubMedDate not supplied

Beta-blockers in hypertensive non-insulin-dependent diabetics: comparison between penbutolol and propranolol on metabolic control and response to insulin-induced hypoglycemia.

In a single blind randomized study the effects of a 4-week administration of propranolol (160 mg/day) and penbutolol (40 mg/day) on metabolic control and insulin-induced hypoglycemia were tested in 8 non-insulin-dependent diabetics with diastolic blood pressure between 95 and 110 mmHg. The recovery from hypoglycemia was not delayed by either drug; hypoglycemic nadir and Conard's K did not change significantly. Symptoms of hypoglycemia were inhibited to a lesser extent and pulse rate decrease was lower after penbutolol vs baseline (65 +/- 2.4 vs 77 +/- 2.4 beats/min, p less than 0.01) than after propranolol vs baseline (61 +/- 1.06 vs 77 +/- 2.4 beats/min p less than 0.001). Both drugs produced similar and significant effects on blood pressure both systolic and diastolic. There were no significant effects on fasting plasma glucose concentration, HbA1c, IRI, urinary C-peptide, triglycerides, total and HDL cholesterol and FFA. IRG decreased after penbutolol vs baseline 60 min after insulin injection (170 +/- 30.8 vs 125 +/- 15.4 pmol/l, p less than 0.05). These results indicate that the use of beta-blockers, in particular penbutolol, for mild to moderate hypertension may be considered the treatment of choice also in non-insulin-dependent diabetics at the therapeutic doses employed.

Blood Glucose↗
PubMedDate not supplied

Eventual error caused by dehydration with pachometry.

Among the possible variables responsible for systemic errors in the acquisition of pachometric measurements, the corneal hydration condition plays a determinant role. In the present study, the authors have investigated the importance of this condition with two different pachometers (Storz Corneoscan II and Allergan Humphrey), reproducing an experimental dehydrated condition. The main datum arising from the comparison of the measurements obtained is represented by the different time course of the value of the measurement in the two groups. In fact, confronting the medium initial superimposed thickness value in the two tables (521 vs. 520 microm) there is a substantial difference in the final examination. For the first group of 60 corneas, the thickness values appear almost identical in the different intervals of time (medium initial thickness 521 vs. 512 microm final thickness). For the group examined with the solid-point machine, a decreasing thickness equal to 7% was evidenced (520 vs. 482 microm) with a significant decrease in the corneal thickness after only 45 s.

Adult↗