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Biomedical subjects

A Violante

Publications and source records attributed to A Violante.

At least 19 recordsLinked to original sources
PubMed1997

Oxygen radicals can induce preconditioning in rabbit hearts.

Indirect evidence suggests that oxygen radicals may contribute to ischemic preconditioning. We directly investigated whether exposure to oxygen radicals per se, in the absence of ischemia, could reproduce the beneficial effects of ischemic preconditioning on infarct size and on postischemic contractile dysfunction. In one branch of the study, isolated rabbit hearts underwent 30 minutes of total global ischemia and 45 minutes of reperfusion (n=6, control group). A second group, before ischemia/reperfusion, was exposed for 5 minutes to a low flux of oxygen radicals generated by purine/xanthine oxidase (P/XO), followed by a 15-minute washout (n=6). Oxygen radical pretreatment significantly improved postischemic recovery of contractile function. We then investigated in another branch of the study whether this preconditioning effect would also reduce infarct size and whether it was mediated by protein kinase C activation. Control hearts were subjected to coronary artery occlusion for 30 minutes, followed by 2.5 hours of reperfusion (n=6). A second group, before coronary occlusion, was exposed to oxygen radicals and washout as described (n=8). A third group was subjected to oxygen radical infusion, but an inhibitor of protein kinase C (polymyxin B, 50 micromol/L) was administered throughout subsequent ischemia (n=7). A fourth group was exposed to oxygen radicals in the presence of scavengers (superoxide dismutase, 250 U/mL; catalase 500, U/mL; n=8). Pretreatment with oxygen radicals markedly reduced infarct size, from 65+/-19% of risk region in controls to 12+/-4% (P<.05). Protein kinase C inhibition significantly attenuated this effect (infarct size, 37+/-9% of risk region; P<.05 versus P/XO; P=NS versus controls). Oxygen radical-induced preconditioning was prevented by scavengers (infarct size, 55+/-14% of risk region; P<.05 versus P/XO; P=NS versus P/XO+polymyxin B). Our data show that in the absence of ischemia, exposure to low concentrations of oxygen radicals can reproduce the beneficial effects of ischemic preconditioning on infarct size and postischemic recovery of left ventricular function. Thus, oxygen radicals might be potential contributors to ischemic preconditioning.

Analysis of Variance↗
PubMed1997

Attributable risks for kidney cancer in northern Italy.

The percent population attributable risk (AR) for kidney cancer was estimated in relation to smoking habits, beta-carotene intake, history of cystitis and family history of kidney cancer, using data from a case-control study conducted between 1985 and 1989 in Milan, northern Italy. The data comprised 133 histologically confirmed cases of incident kidney cancer and 392 controls, admitted to hospital for a wide range of acute, non-neoplastic, non-smoking-related diseases. On the basis of multivariate odds ratios (ORs), smoking habits accounted for about 26% of cases, a low beta-carotene intake for 18%, a history of cystitis for 7%, and a family history of kidney cancer in first-degree relatives for 3% of cases. Ever smoking and low beta-carotene intake combined explained 38% of all kidney cancers, and the combination of these two factors plus a history of cystitis and a family history of kidney cancer explained 45% of the incidence of the disease. Thus, even if available, dietary information was limited and the AR estimates were based on somewhat arbitrary assumptions. A considerable proportion of kidney cancers could be avoided simply by eliminating smoking and increasing consumption of fruit and vegetables in this Italian population. This would mean that about 1,500 kidney cancer deaths every year in the whole of Italy could be avoided.

Adolescent↗
PubMed1991

Normal serum biochemical and hematological parameters in Macaca fascicularis.

The effects of age, sex, pregnancy, were analyzed and data from fasted and fed animals were compared in a population of cynomolgus macaques. No significant sex effects were observed for biochemical values and no changes were found in male hematological parameters in relation to age. Most values of females during pregnancy were within normal ranges. Comparison between fed and fasted animals showed that several biochemical parameters (e.g., ALT, glucose, CPK, LDH) and several hematological parameters (e.g., monocytes, eosinophils, basophils, hemoglobin, MCV, MCHC, and MCH) were affected by food intake.

Age Factors↗
PubMed1990

Pituitary granuloma and pyoderma gangrenosum.

Pyoderma gangrenosum is a rare chronic and recurrent skin disease characterized by progressing lesions from papulopustules to large necrotic sterile ulcers. Its definite etiology remains unknown. In a 40-year-old woman with typical pyoderma gangrenosum an intrasellar mass with suprasellar extension was diagnosed and removed by transsphenoidal surgery. Histopathological features of the lesion were those of a nonspecific granulomatous hypophysitis. Five months postoperatively the patient experienced visual defects and hypopituitarism demonstrated by endocrine evaluation. Computerized tomography showed the recurrence of the intrasellar expanding mass. Extensive and repeated evaluation failed to find any evidence of sarcoidosis, tuberculosis or histiocytosis. Corticosteroid therapy was preferred to surgery and 80 mg daily prednisone produced a dramatic shrinkage of the pituitary pseudotumor. Long-term follow-up studies did not disclose any recurrence of the pituitary granulomatous process nor objective evidence of underlying disease even after steroid dosage has been tapered. The hypothesis of a pituitary localization of pyoderma gangrenosum is suggested by the similarity between the histopathologic findings of the two conditions and the excellent response to steroid therapy.

Adult↗
PubMed1990

[Relation between the production of deoxynivalenol and zearalenone and the mycelial growth of Fusarium graminearum on solid natural substrates].

A toxicogenic strain of Fusarium graminearum which produces DON and ZEA was cultivated on natural solid substrates (wheat, polished rice and hulled rice) under different environmental conditions. The production of both toxins and mycelium growth (in terms of glucosamine) were evaluated to establish the relation between the production of DON and ZEA and the different mycelium growth on the substrates mentioned above. Polished rice was the substrate on which most production of both toxins was obtained. Comparing the three substrates studied, the highest quantities of DON were obtained at a temperature of 27 degrees C during incubation period, being indifferent to the presence of light except in the case of hulled rice. Whereas for ZEA the best conditions in wheat and polished rice were medium temperatures (17 degrees-21 degrees C respectively) and darkness. While in hulled rice the ideal conditions for the production of both toxins were temperature of 27 degrees C and the presence of light. Concerning the mycelium growth, this was very scarce when cultivated in hulled rice, increasing in polished rice and being largest in wheat. The increase or reduction of the mycelium growth in the different substrates was not proportional to the increase or decrease of the production of both toxins. Therefore, production of DON and ZEA could be subjected to the nature of the substrate and environmental conditions, more than the rate of development of Fusarium graminearum in cereal grains.

Food Microbiology↗
PubMed1983

[Capillary networks and osmotic uptake in fungiform papillae].

In the research it has been tested the ability of convoluted capillary network of the fungiform papillae to act as countercurrent ionic exchanger and therefore to give rise a water uptake from the external environment. Manometric determinations of the water inflow during immersion of the tongue in solutions of different osmolality have shown a conspicuous water uptake, osmotic in nature and largely supported by the Na+ absorbed from the external solutions. The Na+ inhibits also the receptor electrical response to the stimulating Ca++ solutions. These observations show that the papillae can be considered as osmotic devices and emphasise also that the Na+ is directly involved in the papillary functional activity.

Animals↗
PubMed1983

[Effect of metavanadate on papillary water uptake].

It has been examined the influence of vanadium on the papillary osmotic water-salts uptake in order to differentiate it from water flow of other biological substrates as amphibia epithelia. Between the different vanadium compounds only the metavanadate is active and only after administration in the abdominal vein. The general influence of metavanadate is a facilitating one and concerns: electrical receptor afferent discharge, osmotic water uptake and ciliary motility. At the papillary level therefore vanadium is not at all an inhibitory agent as observed in many biological substrates. This observation rule out any analogy in the processes of water inflow operating respectively at the fungiform papillae and amphibia epithelia.

Animals↗
PubMed1982

[The electrical activity of olfactory bulb II in the frog].

The paper refers to the extracellular field potentials of frog's olfactory secondary bulb elicited by means of electrical stimulation of vomero-nasal nerve. These potentials become evident as compound waveform both in situ and in vitro and their components are easily reliable to the activity of intrinsic neuronal circuitry of the bulb. The similarity of the field potentials in the olfactory primary and secondary bulbs is discussed.

Animals↗
PubMed1980

[Effect of section of the hypoglossal nerve on the glossopharyngeal-hypoglossal reflex in the frog].

This research concerns the modulation by lingual afferences of the reflex activity of frog XII nucleus. Some informations on the processes utilized to obtain this effect has been achieved by comparing the glossopharyngeal-hypoglossal reflex evoked bilaterally after excision of one hypoglossal nerve. The reflex response and electrotonic potential become more intense omolaterally to the section of XII at the IV-V day; However these effects disappear later (XII-XV day). These observations completely disagree with the presence of a large injury normally produced in the nucleus of XII by retrograde motoneuron degeneration. The reflex facilitation has been attributed therefore to the degeneration of the afferent component which is associated in the amphibia to the XII and exerts centrally a PAD effects.

Animals↗
PubMed1980

[Importance of the degeneration of afferent components of the hypoglossal nerve on the reflex activity of the nucleus of the hypoglossal nerve in the frog].

The section of frog XII cranial nerve facilitates the reflex activity given by its nucleus. Since this positive effects is not dependent upon any motoneurons degeneration, the hypothesis has been put forward that only the afferent component of the XII nerve is able to modulate the reflex activity by means of PAD effect at the solitarius nucleus. This hypothesis has been tested examining the effect both on the glossopharyngeal reflex response and on the DRR following excision respectively of the dorsal root and of the whole hypoglossal nerve. In preparations with a XII dorsal root transected, electrical stimulation of the homolateral glossopharyngeus nerve evoked a much more intense reflex response than at the intact side. The same effect was evident after the section of the whole nerve.

Animals↗
PubMed1980

Functional importance of the taste papillae of Phormia regina M.

Electrophysiological recording from taste papillae of Phormia regina M. after stimulation with sugar (sucrose, glucose, fructose and galactose) and salt solutions (NaCl, KCl, KNO3 and CaCl2) has indicated that: 1) in all cases the responses showed a phasic onset about 30 sec in duration; 2) after sugar stimulation the phasic onset of the response was followed by a slow adapting tonic period; 3) no tonic period was present after NaCl, KCl, or KNO3 stimulation; 4) CaCl2 evoked a typical volleying activity that can be explained by a greater spatial spreading of electrotonic currents. These results indicate that the proboscis can only be maintained in an extended position (enabling food to be ingested) by rithmic firing from the papillae.

Animals↗
PubMed1980

[Activation of afferent pathways and of control frog olfactory bulb and extracellular field potentials].

It has been recorded the extracellular field potentials of the frog's olfactory bulb produced by electrical stimulation of the commissura anterior and small branches of the olfactory nerve. The activation of the commissural system obtain a positive, long-lasting field potential generated at the soma of the granular cells. The olfactory nerve stimulation produce also a positive surface wave bath at the end of bulbar reply: this effect can be attributed to the activation of the bulbar component of commissural system at the NOA. The recognizable electrical effects of the commissural system allow to make clear the sources of the extracellular field potentials in the bulbar neuronal circuits.

Action Potentials↗