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Biomedical subjects

M Marinelli

Publications and source records attributed to M Marinelli.

At least 73 records · Page 4Linked to original sources
PubMed1994

Gene relaxation and aging: changes in the abundance of rat ventral prostate SGP-2 (clusterin) and ornithine decarboxylase mRNAs.

Sulfated glycoprotein 2 (SGP-2) mRNA progressively increased in the ventral prostate of the aging rat, reaching, at 24 months, 4-fold higher than at 3 months. Ornithine decarboxylase (ODC) mRNA peaked at 6 months (4-fold increase), and at 12 and 24 months was maintained at higher levels than at 3 months. ODC enzymatic activity was enhanced at 6 months to a much smaller extent than its own mRNA, the values at 12 and 24 months dropping to below those at 3 months. Putrescine (Put), spermidine (Spd) and spermine (Sp) concentrations also peaked at 6 months (100% increase for Put, 50% for Sp and Spd). At 24 months, Put and Spd were diminished, and Sp was unchanged with respect to the 3-month values. Under the same conditions, glyceraldehyde-3-phosphate dehydrogenase mRNA did not undergo significant alterations.

Aging↗
PubMed1994

Interactions between the renin-angiotensin system and prostanoids in modulating renal function in potassium-depleted healthy women.

Plasma renin activity (PRA) and urinary aldosterone excretion were determined in healthy women with normal potassium balance (N, n = 20) or experimental potassium depletion (KD). KD was induced by natriuretic treatment--associated with replacement of net NaCl and water losses--and low dietary potassium intake (< or = 10 mmol/d). By using different depletion patterns, three groups were obtained with cumulative potassium deficits (mean +/- SEM) of 160 +/- 43 (KD1, n = 8), 198 +/- 22 (KD2, n = 6) and 215 +/- 54 mmol (KD3, n = 6). The renal function by the clearance (cl.) method and urinary concentrations of prostaglandin E2 (PGE2), 6-keto-PGF1 alpha (6KPGF), and thromboxane B2 (TXB2) by the RIA method were estimated during hypotonic polyuria (oral water load) and subsequent moderate antidiuresis induced by low-dose infusion of lysine-8-vasopressin (LVP). 1. In all KD groups the depletion treatment significantly reduced both potassium plasma concentration (PK) and urinary potassium excretion while it increased basal PRA; the basal urinary aldosterone excretion was not significantly different from normokalemic controls. In the KD3 vs KD1 group the P kappa value was significantly lower. 2. In both KD2 and KD3 groups as compared to the N group, several hypokalemic-like renal dysfunctions--absent in the KD1 group--occurred. Particularly, in the KD2 + KD3 vs N group the renal ability in both urine diluting (water load) and concentrating (LVP infusion) was significantly impaired.(ABSTRACT TRUNCATED AT 250 WORDS)

6-Ketoprostaglandin F1 alpha↗
PubMed1994

Effects of angiotensin-converting enzyme inhibition on renal dysfunction induced by moderate potassium depletion in healthy women.

The role of the renin-angiotensin system in renal hypokalaemic dysfunction has been investigated by evaluating the effects of the angiotensin (AT)-converting enzyme inhibition by enalapril. Healthy women were studied either in normal potassium balance (N3, n = 6) or moderate potassium depletion (KD3, n = 6). Potassium depletion (KD) was induced by low potassium dietary intake (greater than or equal to 10 mmol per day) and natriuretic treatment associated with replacement of net NaCl and water losses; the cumulative potassium deficit achieved was 214 +/- 54 mmol. The renal function and the urinary excretions of some prostanoids (PGE2, 6-keto-PGF1 alpha, TxB2) were evaluated during hypotonic polyuria (oral water load) and subsequent moderate antidiuresis (lysine-8-vasopressin (LVP) low-dose infusion). Paired studies were performed in absence (control) and presence of enalapril. Basal plasma renin activity (PRA) and urinary aldosterone excretion were determined before the water load of control studies. Renal dysfunction typical of chronic KD occurred in the KD3 group, i.e. increase in PRA, decrease in creatinine clearance, depression of the diuretic response to water load, inhibition of distal fractional chloride reabsorption, and blunted efficacy of LVP in increasing the urinary solute concentration. The urinary prostanoid excretions were reduced. Basal urinary aldosterone excretion was not changed significantly. In KD3 group enalapril decreased mean arterial pressure (MAP), increased the plasma potassium concentration, improved the diuretic response to water load and corrected the impairment of the distal fractional chloride reabsorption. Despite the decrease in MAP enalapril did not affect significantly the creatinine clearance. Neither urinary prostanoid excretions nor the renal response to LVP were affected by the drug. The data suggest that in KD the increased activity of the renin-angiotensin system affected the renal function both through direct effects and through effects dependent on the angiotensin-supported secretions of aldosterone and probably of vasopressin. Finally, by comparing the effects of enalapril and indomethacin in experimental groups with an equivalent degree of KD, evidence is provided in favour of the interaction between renin-angiotensin and prostanoid systems in controlling the glomerular filtration rate and the salt and water handling by renal tubules.

Adult↗
PubMed1994

Cortisol, testosterone, and free testosterone in athletes performing a marathon at 4,000 m altitude.

Cortisol, testosterone, free testosterone and the ratio between free testosterone and cortisol (FTCR) were monitored in six athletes participating in a marathon starting at 3,860 and finishing at 3,400 m, having reached the top at 5,100 m altitude. Blood was drawn at sea level before the departure for the mountain area, after a week of acclimatization, immediately after the marathon and after a 24-hour recovery period from the run. Cortisol increased after acclimatization and especially after the marathon; it decreased to normal values after recovery. Testosterone decreased after acclimatization, especially after the run; it presented a partial recovery 24 h after the race. Free testosterone did not decrease after acclimatization and presented partial recovery. FTCR could also be useful for monitoring fitness, overtraining and overstrain in strenuous and ultraendurance exercise.

Adult↗
PubMed1994

Growth hormone and insulin-like growth factor I in athletes performing a marathon at 4000 m of altitude.

Human growth hormone (hGH) characteristically increases during physical exercise. In sports medicine, hGH changes have mostly been described in short-term performances under standardized laboratory procedures. We studied hGH and insulin-like growth factor I (IGF-I) under field conditions in 7 runners performing a marathon at 4000 m of altitude, to study the hormonal changes under extreme endurance effort and to evaluate the release of 22 kDa and 20 kDa monomers under these conditions, in comparison with a control group. The blood samples were taken at sea level, after 1 week of acclimatization, immediately after the run, and after a recovery of 24 h from the marathon. hGH was quantified by using a polyclonal method, a 22 kDa specific monoclonal method and a monoclonal method recognizing both 22 kDa and 20 kDa isoforms. A significant increase in hGH was noted using all methods after the marathon, followed by a significant decrease after recovery. Significant differences between athletes and controls were found only for the measurement after the marathon. No statistically reliable decrease of IGF-I was observed in athletes and controls. We obtained more limited hGH rises than previously described in athletes; the importance of lactate levels indicates that the use of physical exercise as a stimulation test for hGH should be closely standardized. The 20 kDa monomer and other hGH molecular forms played a limited role in the hormone increase: in our experience, elevation of hGH in heavy exercise corresponds mostly to the 22 kDa isoform. We suggest that the evaluation of hGH elevation in sports medicine could be accurately performed using specific 22 kDa monoclonal assays.

Adult↗
PubMed1994

Corticosterone circadian secretion differentially facilitates dopamine-mediated psychomotor effect of cocaine and morphine.

Studies of intravenous self-administration and psychomotor effects of drugs have recently suggested that stress-induced corticosterone secretion may be an important factor determining vulnerability to drugs of abuse. In this report, we studied if basal physiological corticosterone secretion modulates sensitivity to cocaine and morphine, and if changes in the reactivity of mesolimbic dopaminergic (DA) neurons, one of the principal substrates of drug-reinforcing effects, are involved. For this purpose we determined the psychomotor effects of these drugs in animals in which corticosterone secretion was suppressed by adrenalectomy and in adrenalectomized animals submitted to different corticosterone replacement therapies designed to mimic (1) only the diurnal levels of the hormone, obtained by the subcutaneous implantation of 50 mg corticosterone pellets; (2) only the nocturnal levels, obtained by adding corticosterone (50 micrograms/ml) to the drinking solution during the dark period; and (3) the entire circadian fluctuation, obtained by combining the two previous treatments. Locomotor response to cocaine and morphine was studied after both systemic and central injections, into the nucleus accumbens for cocaine and into the ventral tegmental area for morphine. These sites were chosen because stimulant effects of cocaine and morphine injected in these structures are dopamine dependent. Our results show that suppression of corticosterone by adrenalectomy reduced the locomotor response to cocaine and morphine, injected both systemically and centrally. The reinstatement of diurnal levels of corticosterone totally reversed adrenalectomy's effects on the behavioral response to cocaine, whereas the reestablishment of the entire corticosterone circadian fluctuation (diurnal plus nocturnal levels) was necessary to reverse the response to morphine.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenalectomy↗
PubMed1993

Progeny of mothers drinking corticosterone during lactation has lower stress-induced corticosterone secretion and better cognitive performance.

In order to test the hypothesis that maternal corticosterone influences hypothalamus-pituitary-adrenal (HPA) system activity in the adult rat and behaviors related to it, we induced a moderate increase in maternal plasma level of corticosterone by adding the hormone to the drinking water of the dams (200 micrograms/ml) from the day after delivery to weaning. Our previous experiments have shown that this procedure produces plasma levels of the hormone in the range of those following a mild psychic stress (from 4.3 +/- 0.5 to 9.5 +/- 1.8 micrograms/100 ml in the dams, and from 0.7 +/- 0.1 to 1.2 +/- 0.2 micrograms/100 ml in the pups at 10 days of lactation). Adrenal weights were slightly and temporarily decreased by treatment in both mothers and offspring. Only the male progeny was investigated in this study. Corticosterone-nursed rats had significantly less corticosterone and ACTH in basal conditions and after a 2 min restraint stress at 3 months of age, and showed better performances at weaning and at 1, 2 and 3 months of life in the Morris water maze. Our results demonstrate that a moderate increase in maternal corticosterone during lactation influences the activity of HPA axis and improves spatial learning ability of the adult offspring.

Adrenal Glands↗
PubMed1993

Usefulness of free testosterone/cortisol ratio during a season of elite speed skating athletes.

Free testosterone/cortisol ratio (FTCR) was used in eight elite speed skaters (five males, three females), during an eight-month season, to study the effectiveness of the hormonal parameter as a marker of the condition of overstrain and/or incomplete recovery. We did not find values lower than 0.35 x 10(-3). We confirmed the reliability of the criterion of FTCR decrease of 30% or more to indicate temporary incomplete recovery from intensive training and residual weariness and, consequently, of reduced effectiveness for competitive purposes; a formula was used in this case to calculate FTCR. When FTCR was calculated by using directly measured FT, we remarked that such threshold criterion could not be used and the significant decrease was of 18% or more. The major problem of FTCR is the limitation of its use to male athletes, although the trend found in females was similar to that presented in males. FTCR is a useful index in elite speed skaters: broader application of this index and further investigation are required to set testing times, to use direct measurement of free testosterone and, finally, to find an equivalent support for women.

Adult↗
PubMed1993

A personal dosimeter prototype for static magnetic fields.

A personal dosimeter prototype, for static magnetic fields with three Hall probes, has been designed and built to provide a reliable instrument for long-term analysis. The probe output signals, proportional to the magnetic flux density components of the vector B, are filtered, sampled, and stored in a buffer memory sufficient to cover a whole worker shift. The data sampling rate is high enough to record the operator movements within the fringes of the magnetic field. The content of the buffer memory is then transferred on a personal computer and registered on individual dosimetric cards. The data can be used for personal exposure monitoring.

Electromagnetic Fields↗