Naloxone decreases the inhibitory effect of ethanol on the release of arginine-vasopressin induced by physical exercise in man.

To establish whether ethanol and/or endogenous opioids play a role in the control of arginine-vasopressin (AVP) response to physical exercise, six healthy men underwent six bicycle-ergometer tests until exhaustion [exercise control test; exercise plus ethanol (50 of 110 ml proof whiskey orally), exercise plus naloxone (2 mg injected plus 5 mg infused or 4 mg injected plus 10 mg infused intravenously] or exercise plus ethanol plus naloxone). Plasma AVP levels, physiological and biochemical variables were measured during tests. Physiological and biochemical variables were similar in all tests. During the control test, exercise significantly increased plasma AVP levels, with a peak value five times higher than baseline. The AVP response to exercise was similar in the presence of naloxone, whereas it was abolished by ethanol. When ethanol tests were repeated in the presence of naloxone, at both lower and higher dose, ethanol inhibition on AVP secretion was only partial, with mean peak responses 2.5 times higher than basal values. Results indicate an ethanol involvement in regulation of the AVP response to physical exercise. Furthermore, naloxone-sensitive endogenous opioids appear to play a role in the mechanism underlying ethanol inhibitory action, but not in mediation of the AVP response to physical exercise.

Negative energy modes and gravitational instability of interpenetrating fluids.

We study the longitudinal instabilities of two interpenetrating fluids interacting only through gravity. When one of the constituents is of relatively low density, it is possible to have a band of unstable wavenumbers well separated from those involved in the usual Jeans instability. If the initial streaming is large enough, and there is no linear instability, the indefinite sign of the free energy has the possible consequence of explosive interactions between positive and negative energy modes in the nonlinear regime. The effect of dissipation on the negative energy modes is also examined.

Difference between diabetic and nondiabetic smokers in the pituitary response to physical exercise.

The growth hormone (GH), cortisol, and arginine vasopressin (AVP) responses to bicycle ergometry (with increasing workload until exhaustion) were measured in 20 patients affected by insulin-dependent diabetes mellitus (IDDM) (10 habitual smokers and 10 nonsmokers) and 20 nondiabetic subjects (normal controls) (10 habitual smokers and 10 nonsmokers). Cardiorespiratory parameters such as heart rate, blood pressure, ventilation, frequency of breathing, tidal volume, oxygen consumption (Vo(2)), carbondioxide production (Vco(2)), and respiratory exchange ratio (R) were monitored before and during exercise tests. No significant differences between groups were observed; furthermore, there were no differences in circulating somatomedin-C (SM-C) and free fatty acids (FFA) levels between groups. Blood glucose levels were similar before exercise and followed a similar pattern during tests in diabetic smokers and nonsmokers. Basal GH, cortisol, and AVP levels were similar in diabetic smokers, diabetic nonsmokers, normal smokers, and normal nonsmokers. In all groups, exercise induced a significant increase in the serum concentrations of all examined hormones. Increments were significantly higher in diabetic than in nondiabetic groups. No significant differences were observed between diabetic smokers and nonsmokers for all examined hormones. AVP responses during tests were similar in normal smokers and nonsmokers. In contrast, exercise-induced GH and cortisol increments were significantly lower in normal smokers than in normal nonsmokers. These data support the hypothesis that in normal subjects habitual nicotine consumption may attenuate both GH and cortisol responses to a releasing stimulation, such as physical exercise. This phenomenon may represent an expression of adaptation of nicotinic neurotransmission to chronic stimulation. Furthermore, the data show that the effect induced by habitual smoking is absent in diabetics, probably because of diabetes-induced neuroendocrine alterations in the central nervous system.

Pattern of human blood spermidine and spermine in prematurity.

Blood polyamines have been determined in preterm newborns (24-37 gestation weeks) during the first hours of life and until 20 days after birth. The most elevated polyamine concentrations were found in preterm newborns from the 24th-33rd gestational week. In all preterms, however, polyamine concentrations are higher than in full term newborns. In preterm infants two different patterns of blood polyamines appear in relation to the gestational age: in infants born at 24-34 wk, spermidine reaches the peak at 12 h and spermine shows high concentrations between 12 and 48 h. In infants born at 35-37 wk maximal concentrations of polyamines were reached at 12 h. Successively, in both groups the polyamines progressively decrease up to the 20th day, with some individual variations. Our results may provide a further support to the suggestion of a fetal genesis of polyamines and their involvement in fetal growth.

Changes of polyamine concentrations in infants during the first six months of life.

Polyamines were detected in the blood of infants during the first six months of life. The highest spermidine levels were found at the 2nd and the 4th month after birth. Spermine, on the contrary, does not show significant differences. Different types of diet produced no changes in the polyamine pattern.

Separation and characterization of histones and acidic proteins from heart muscle and calf thymus.

A method for the isolation of histones and acidic proteins extracted from rabbit heart and calf thymus chromatins has been studied. The histones present five major electrophoretic fractions in both tissues. Only lysine rich fraction in the heart splits into three peptides of different mobility. Amino acid composition of total histones shows values very similar in almost all components. The acidic proteins of rabbit heart and calf thymus have been characterized by sodium dodecyl sulphate polyacrylamide gel electrophoresis and by amino acid composition. The electrophoretic pattern reveals reproducible heterogeneous banding pattern from the two sources with different degree of phosphorylation. The amino acid composition of total acidic proteins is quite similar with the exception of serine content that in the heart is most elevated.

Tissue polyamine concentrations in the European sea bass (Dicentrarchus labrax L.): change with age and season of the year.

Independently of the age of the European sea bass, putrescine and spermidine are much higher in liver and brain than in muscles, while spermine concentrations are more similar to one another. The polyamine concentrations are higher in 2 years old sea bass than in 1 year old fish except for heart spermidine and liver spermine. Lowering in water temperature causes a decrease in the concentration of spermidine and spermine in all tissues examined. Putrescine, however, increases in heart, caudal muscle, liver and brain and it is unchanged in red and dorsal muscles.

Effect of naloxone on somatostatin inhibition of arginine vasopressin response to physical exercise in normal men.

To establish whether somatostatin (SRIH) and/or endogenous opioids play a role in the control of arginine-vasopressin (AVP) response to physical exercise, eight healthy men underwent four bicycle-ergometer tests until exhaustion: exercise control test; exercise plus SRIH, naloxone or SRIH plus naloxone. Serum AVP levels, physiological and biochemical variables were measured during tests. Physiological and biochemical variables were similar in all tests. During control test exercise significantly increased serum AVP levels, with a peak value 4.1 times higher than baseline. The AVP response to exercise was similar in the presence of naloxone, whereas it was significantly reduced by SRIH (AVP peak was only 2.8 times higher than baseline). When SRIH and naloxone were given together, the exercise-induced AVP rise was comparable to that observed in the control test. Results indicate a somatostatinergic involvement in the regulation of the AVP response to physical exercise. Furthermore, naloxone-sensitive endogenous opioids appear to play a role in the mechanism underlying SRIH inhibitory action, but not in mediation of the AVP response to physical exercise.

Free fatty acids inhibit adrenocorticotropin and cortisol secretion stimulated by physical exercise in normal men.

BACKGROUND: The basal circulating levels of ACTH and cortisol, but not the ACTH/cortisol response to hCRH, are significantly reduced by free fatty acid (FFA) infusion. OBJECTIVE: To verify whether FFA infusion modifies the ACTH/cortisol response to physical exercise, a well-known activator of the HPA axis at suprapituitary level. DESIGN: Exercise tests on a bicycle ergometer during infusion of a lipid-heparin emulsion (LHE) (experimental test) or normal saline (NaCl 0.9%) (control test). SETTING: Department of Cardiology at the University-Hospital. SUBJECTS: Seven healthy male subjects aged 25-33 years. INTERVENTIONS: On two mornings, at weekly intervals, LHE or saline were infused for 60 min; infusion started 10 min before exercise test on a bicycle ergometer, which lasted about 15 min. MAIN OUTCOME MEASURES: Circulating ACTH/cortisol levels and physiological variables during physical exercise. RESULTS: FFA levels (0.4 +/- 0.1 mEq/l) remained constant during control test, whereas they progressively rose (peak at 60 min, 2.7 +/- 1.0 mEq/l) during LHE infusion. Neither basal nor exercise-induced changes in physiological variables were modified by LHE infusion. Both ACTH and cortisol increased during exercise, with peak levels at 20 min and 30 min (control test: 103% and 42%, P < 0.001; experimental test: 28.5% and 18.6%, P < 0.05 higher than baseline, respectively). Both ACTH and cortisol responses were significantly lower in the experimental than in the control test (at 20 min P < 0.002 and at 30 min P < 0.05 for ACTH; at 20 min P < 0.05 and at 30 min, 40 min and 50 min P < 0.001 for cortisol). CONCLUSIONS: These data represent the first demonstration of an inhibitory action of increased circulating FFA levels on the HPA axis under stimulatory conditions (i.e. physical exercise, a challenge acting at suprapituitary level). In contrast, previous studies did not show FFA effects on the CRH-induced ACTH/cortisol response. Therefore, our data suggest negative effects of FFAs on the HPA axis at hypothalamic or higher centres in the central nervous system.

Correlates of HIV, HBV, and HCV infections in a prison inmate population: results from a multicentre study in Italy.

A cross-sectional study was undertaken on the correlates of infection for the human immunodeficiency virus (HIV) and hepatitis viruses B and C (HBV and HCV) in a sample of inmates from eight Italian prisons. A total of 973 inmates were enrolled [87.0% males, median age of 36 years, 30.4% intravenous drug users (IDUs), 0.6% men who have sex with men (MSWM)]. In this sample, high seroprevalence rates were found (HIV: 7.5%; HCV: 38.0%; anti-HBc: 52.7%; HBsAg: 6.7%). HIV and HCV seropositivity were associated strongly with intravenous drug use (OR: 5.9 for HIV; 10.5 for HCV); after excluding IDUs and male homosexuals, the HIV prevalence remained nonetheless relatively high (2.6%). HIV prevalence was higher for persons from Northern Italy and Sardinia. The age effect was U-shaped for HIV and HCV infections; HBV prevalence increased with age. Tattoos were associated with HCV positivity (OR: 2.9). The number of imprisonments was associated with HIV infection, whereas the duration of imprisonment was only associated with anti-HBc. The probability of being HIV-seropositive was higher for HCV-seropositive individuals, especially if IDUs. In conclusion, a high prevalence of HIV, HCV, and HBV infections among inmates was observed: these high rates are in part attributable to the high proportion of IDUs. Frequency of imprisonment and tattoos were associated, respectively, with HIV and HCV positivity. Although it is possible that the study population is not representative of Italy's prison inmate population, the results stress the need to improve infection control measures users was prisons.

[Changes in the specific activity and content of free nucleotides and polyamines of the infarct and pre-infarct area of the revascularized dog heart]. / Variazioni nell'attività specifica e nel contenuto dei nucleotidi liberi e delle poliamine dell'area infartuale e perinfartuale del cuore di cane rivascolarizzatto?29H

Changes on specific radioactivity and levels of free nucleotides and polyamines in infarcted and borderline tissue of reperfused dog heart. The changes on specific radioactivity and levels of free nucleotides and polyamines, spermine and spermidine, of reperfused heart show a different behaviour of the anoxic myocardium. An increase of both specific activity and levels of free nucleotides and polyamines after 30 minutes of ischemia is observed. A longer period of anoxia (6 hours) causes a decreased synthesis and concentration of free nucleotides and polyamines. A remarkable recovery of specific activity of these compounds after reperfusion is noted. The borderline tissue shows a similar behaviour but with smaller changes. Therefore, in our experimental conditions, ischemia does not cause an irreversible alteration in protein synthesis mechanism of myocardial cells. In addition, the reperfusion may cause a recovery of biochemical mechanisms that control the functional capacity of the cell. The polyamine changes may postulate a central role of these amines in both anoxic and reperfused heart.

[Circadian rhythm of poly A polymerase in rat liver nuclei]. / Ritmo circadiano dell'attività poli (A) polimerasica in nuclei di fegato di ratto.

Isolated nuclei from the liver of rats maintained under daily scheduled conditions of light (12 hrs) and food (8 hrs) showed a peak of Mn2+-dependent poly (A) polymerase activity 6 hrs after the beginning of the feeding period, as shown by DNA dependent RNA polymerase B. In fasting animals the peak of poly (A) polymerase occurs at 18.00.

[Circadian rhythm of poly A polymerase in chromatin and nucleoplasmatic extract of rat liver]. / Ritmo circadiano dell'attività poli (A) polimerasi in cromatina ed estratto nucleoplasmatico di fegato di ratto.

Chromatin preparations from the liver of rats accustomed to eating during the first 8 hrs of a daily 12 hrs dark period exhibit the same fluctuations of poly (A) polymerase as whole nuclei (a peak at 15.00 in fed rats, a peak at 18.00 in fasting ones). Nucleoplasmic activity was detectable only on addition of exogenous primer.