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Biomedical subjects

P Davalli

Publications and source records attributed to P Davalli.

29 records · Page 2Linked to original sources
PubMed1983

Peptide chain initiation and analysis of in vitro translation products in rat heart undergoing hypertrophic growth.

The cytosol fraction of rat heart contains an initiation factor-like protein component that behaves like the eukaryotic factor (eIF-2) in binding [35S]-Met-tRNAf in the presence of GTP. The ternary initiator complex thus formed is able to bind to heart ribosomes. In the left ventricle of rat heart undergoing hypertrophic growth upon constriction of the descending aorta, the [35S]-Met-tRNAf binding activity of the cytosol protein(s) gradually increases after the operation from 40%, at 48 h, to 90%, at 10 days; slightly lower activation is seen in the [35S]-Met-tRNAf binding to ribosomes. Polysomal RNA is extracted from sham operated and hypertrophic rat hearts and translated in a reticulocyte cell free system. The translation products are analyzed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis: no clearcut qualitative difference is observed in the pattern obtained from sham operated and hypertrophic animals.

Animals↗
PubMed1979

[Specific activity and release of norepinephrine in isolated and perfused rabbit hearts under various oxygen pressure].

The incorporation of 3H-tyrosine into norepinephrine of rabbit hearts perfused with Krebs-Henseleit solution containing 11 mM glucose and gassed with 95% O2 - 5% CO2 (control) or 80% O2 - 5% CO2 15% N2 (hypoxic) or 95% N2 - 5% CO2 (anoxic), was studied. In the control hearts a constant specific activity of norepinephrine without any release of catecholamine into coronary effluent was measured after 5, 15, 30, 60 minutes. The hypoxic perfusion while not causing any release of norepinephrine, produced a significant increase in tyrosine incorporation into norepinephrine. The specific activity of norepinephrine and its release into coronary effluent were increased by anoxic perfusion; this effect was most evident when the glucose was replaced with a solution containing 11 mM mannitol. These results suggest that the synthesis of norepinephrine in isolated hearts, lacking of sympathetic innervation, may be affected by different condition of oxygen supply.

Animals↗
PubMed1979

RNA and protein synthesis in rat brain during exercise. Effect of arginine and some phosphorylated amino acids.

RNA and protein synthesis is noticeably depressed in the brain of swimming rats. Repeated oral administration of phosphothreonine, phosphoserine or arginine is susceptible of improving brain macromolecular synthesis. A parallel induction is observed on spermine and spermidine accumulation, particularly evident when arginine is used. The anti-fatigue effect of phosphorylated amino acids or arginine may be associated with the observed restoration of brain macromolecular synthesis via polyamine accumulation.

Amino Acids↗
PubMedDate not supplied

Increased brain concentrations of polyamines in rats with encephalopathy due to a galactosamine-induced fulminant hepatic failure.

Polyamine concentrations including putrescine, spermidine and spermine were documented in two brain areas of rats with mild and severe stages of hepatic encephalopathy (HE) due to fulminant hepatic failure induced by galactosamine HC1 injection (3 g kg-1 i.p.). In the mild stage of HE putrescine increased by 3-4 times whereas spermidine and spermine showed a slight increase. The scenario, however, was found to be changed going from the mild to the severe stage of HE, since in this last stage spermidine and spermine showed a further rise while putrescine was found to be significantly lower than in the mild stage of HE in both the brain areas studied. The changes in the ratio among the three polyamines with an enhanced prevalence in the severe stage of HE of spermidine and spermine are likely to be related to the exhaustion of the synthetic pathway of putrescine or to a reduction of the interconversion to this polyamine from spermidine and spermine. Considering that these last two polyamines potentiate the N-methyl-D-aspartate glutamate receptor mediated toxicity and that they might exert neurotoxic effects per se, there are clear reasons for suspecting an implication of the described changes of polyamines in the neurochemical mechanism which sustain HE and to surmise a potential therapeutic effect in this pathology of non-competitive antagonists of polyamine-site on N-methyl-D-aspartate glutamate receptors.

Animals↗
PubMedDate not supplied

Increased levels of clusterin mRNA in the ventral prostate of the aging rat are associated to increases in cuboidal (atrophic) cell population and not to changes in apoptotic activity.

In the ventral prostate of the intact rat, clusterin mRNA is expressed in a small population of cuboidal epithelial cells undergoing apoptosis, but not in the columnar cells comprising the vast majority of the glandular epithelium. Upon castration, clusterin mRNA expression and apoptotic activity are turned off in the cuboidal cells and turned on in the columnar ones. We show here that the progressive enhancements in the abundance of clusterin mRNA, occurring in the rat ventral prostate upon aging, are based on increases of the cuboidal cells at the expense of the columnar ones. DNA fragmentation, a typical sign of apoptosis, assayed both by agarose gel electrophoresis and in situ staining, was undetectable in 3-month-old rats but was evident among the cuboidal cells of 24-month-old animals and columnar cells of 1-day castrates. The DNA content of the ventral prostate did not change significatively between young and old rats, indicating that no increase in the rate of cell death occurs within the age interval examined. It is concluded that the enhancement in cuboidal cell population, the consequent augmented accumulation of clusterin mRNA, and the increased frequency of DNA fragmentation that we have detected in the aging rat ventral prostate are not directly related to the rate of apoptosis.

Aging↗
PubMedDate not supplied

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.

Aging↗