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Biomedical subjects

F Rossi

Publications and source records attributed to F Rossi.

At least 19 recordsLinked to original sources
PubMed1992

Interactive role of L-glutamate and vasopressin, at the level of the PAG area, for cardiovascular tone and stereotyped behaviour.

The periaqueductal gray (PAG) area may modulate cardiovascular functions and trigger several stereotyped behavioural responses through a mechanism mediated by the interaction of L-glutamate with arginine vasopressin (AVP). Moreover, only the NMDA- but not the non-NMDA-glutamergic subtype receptors might participate in the control of these neurovegetative functions also modifying the homeostasis of the hypothalamic-neurohypophysis system. This latter effect may be due to the tight connections between the PAG area neurons to the more cephalic nuclei within the brainstem.

Animals↗
PubMed1992

Pregnenolone sulfate increases the convulsant potency of N-methyl-D-aspartate in mice.

The neurosteroid pregnenolone sulfate is known to specifically enhance NMDA-gated currents in spinal cord neurons. The response does not appear to be mediated by the glycine/NMDA modulatory site. Here we found that pregnenolone sulfate significantly increased the convulsant potency of N-methyl-D-aspartate (NMDA), but not of pentylenetetrazol (PTZ). In agreement with previous in vitro reports showing that the glutamergic NMDA receptor is also specifically modulated by steroids, our findings suggest that pregnenolone sulfate selectively activates the NMDA receptors involved in convulsions in the intact animal.

Animals↗
PubMed1992

Plasmid transformation of Ruminococcus albus by means of high-voltage electroporation.

To apply recombinant DNA techniques to the genetic manipulation of cellulolytic ruminal bacteria, a plasmid vector transformation system must be available. The objective of this work was to develop a system for plasmid transformation of Ruminococcus albus. Using high voltage electrotransformation, pSC22 and pCK17 plasmid vectors, derived from lactic acid bacteria plasmids and replicating via single-stranded DNA intermediate, were successfully introduced into three freshly isolated R. albus strains and into R. albus type strain ATCC 27210. The optimization of the electrotransformation condition raised the electroporation efficiency up to 3 x 10(5) transformants per microgram of pSC22 plasmid.

DNA, Bacterial↗
PubMed1992

Evidence for the involvement of distinct signal transduction pathways in the regulation of constitutive and interferon gamma-dependent gene expression of NADPH oxidase components (gp91-phox, p47-phox, and p22-phox) and high-affinity receptor for IgG (Fc gamma R-I) in human polymorphonuclear leukocytes.

We recently showed that mRNA levels coding the high-affinity Fc gamma receptor for IgG (Fc gamma R-I, CD64) and two of the components of the phagocytic superoxide anion-generating system--the heavy-chain subunit of cytochrome b558 (gp91-phox) and the 47-Kd cytosolic factor (p47-phox)--are modulated by interferon gamma (IFN-gamma). In this study, we examined whether dexamethasone (DEX) affects gp91-phox and p47-phox mRNA expression of human polymorphonuclear leukocytes (PMN), treated or not with IFN-gamma. We also investigated whether staurosporine, a general inhibitor of protein kinases, influences gp91-phox, p47-phox, and Fc gamma R-I gene expression in PMN treated with or without IFN-gamma. We found that (1) gp91-phox mRNA steady-state levels, expressed in control or IFN-gamma-treated PMN, were significantly inhibited, in a dose-dependent fashion, by both DEX and staurosporine; (2) p47-phox mRNA steady-state levels, expressed in control or IFN-gamma-treated PMN, were not influenced by DEX, but were markedly depressed by staurosporine; (3) no changes of spectrophotometric cytochrome b558 were found in PMN treated for up to 20 hours with the inhibitors, regardless of the presence of IFN-gamma; (4) both DEX and staurosporine dose-dependently inhibited IFN-gamma-induced Fc gamma R-I mRNA and protein expression; and (5) stability of gp91-phox and Fc gamma R-I messages in IFN-gamma-treated PMN was not altered by the presence of DEX. Our results demonstrate that gp91-phox, p47-phox, and Fc gamma R-I gene expression of PMN is governed by specific and independent biochemical pathways. Moreover, IFN-gamma activates different signal transduction pathways to modulate mRNA expression of gp91-phox, p47-phox, and Fc gamma R-I.

Alkaloids↗
PubMed1992

Prevalence of hereditary ataxias and spastic paraplegias in Molise, a region of Italy.

An epidemiological survey of hereditary ataxias and paraplegias was conducted in Molise, a region of Italy (335, 211 inhabitants on 1 January 1989). Total prevalence was 7.5 x 10(-5) inhabitants (95% confidence limits 4.8-11.1). There were 7 patients with Friedreich's disease, 5 with early onset cerebellar ataxia with retained tendon reflexes, 4 with ataxia-telangiectasia, 9 with hereditary spastic paraplegias (2 autosomal dominant and 7 autosomal recessive cases). There was no patient with autosomal dominant cerebellar ataxia.

Adolescent↗
PubMed1992

Participation of arginine vasopressin-mediated and adrenergic system-mediated mechanisms in the hypertension induced by intracerebroventricular administration of NMDA in freely moving rats.

Effects of intracerebroventricular (third ventricle) injection of N-methyl-D-aspartate (NMDA) on arterial blood pressure, on heart rate, on arginine vasopressin (AVP) and levels of catecholamines in plasma and on the behaviour of normotensive freely-moving rats have been evaluated. N-Methyl-D-aspartate significantly (P less than 0.01) increased arterial blood pressure and levels of catecholamines and AVP in plasma. With 0.1-1.0 micrograms/rat all animals presented psychomotor agitation, stereotyped movements, hyperexcitability, exophthalmus, dyspnoea, jumping, rearing and teething. The selective antagonist for NMDA receptors, 2-APV injected in the third ventricle, significantly (P less than 0.01) antagonized the hypertension, the increase in levels of catecholamines and AVP in plasma and behavioural effects. An antagonist of alpha 1 adrenergic receptors, prazosin (i.v.), an agonist of alpha 2 adrenergic receptors, clonidine (i.c.v.) and a relatively selective antagonist of V1 subtype of receptor of AVP, CGP 25838 (i.c.v. and i.v.), 15 min before NMDA, significantly (P less than 0.01) decreased the effects induced by the injections of NMDA. On the contrary, an antagonist of opiate receptors, naloxone (i.v.), 15 min before NMDA, significantly (P less than 0.01) increased the NMDA-induced modifications. Pretreatment with the antagonists at these doses, did not significantly modify the basal values of arterial blood pressure and behaviour. Only 2-APV sometimes induced ataxia, lasting about 5 min. This study points out an increase in the central sympathetic efferent activity and in release of AVP involved in the NMDA-induced cardiovascular and behavioural effects.

2-Amino-5-phosphonovalerate↗
PubMed1992

Molecular dynamics simulation in vacuo and in solution of [Aib5,6-D-Ala8] cyclolinopeptide A: a conformational and comparative study.

The conformation of a Cyclolinopeptide A analogue, c-(Pro-Pro-Phe-Phe-Aib-Aib-Ile-D-Ala-Val), has been investigated by means of molecular dynamics simulations, in various molecular environments. The molecular dynamics results are compared with that obtained for Cyclolinopeptide A and a detailed analysis of the different behaviour for the two compounds is reported. A complete analysis of hydrogen bonds is presented.

Amino Acid Sequence↗
PubMed1992

Effects of teicoplanin on human platelet aggregation in vitro and ex vivo.

The effects of teicoplanin on adenosine-diphosphate (ADP)-induced human platelet aggregation in vitro and on both ADP- and ristocetin-induced human platelet aggregation ex vivo were investigated. In the in vitro study carried out on platelets from 7 healthy volunteers, teicoplanin had no effect on platelet function even at a concentration (1 mg/ml) 10 times higher than the peak level found in the in vivo state, but at the highest concentration (10 mg/ml), which is 100 times higher than that reached in vivo, it inhibited ADP-induced platelet aggregation. In the ex vivo studies carried out in 10 healthy volunteers, teicoplanin, following single intravenous doses of 400 mg and 800 mg, did not produce any effect on platelet function up to 6 hours after administration. After 12 hours, teicoplanin, when given at 800 mg i.v., reduced ADP-induced platelet aggregation.

Adult↗
PubMed1992

Generation of signals activating neutrophil functions by leukocyte integrins: LFA-1 and gp150/95, but not CR3, are able to stimulate the respiratory burst of human neutrophils.

To address the question whether leukocyte integrins are able to generate signals activating neutrophil functions, we investigated the capability of mAbs against the common beta chain (CD18), or the distinct alpha chains of CR3, LFA-1, or gp150/95, to activate neutrophil respiratory burst. These investigations were performed with mAbs bound to protein A immobilized to tissue culture polystyrene. Neutrophils plated in wells coated with the anti-CD18 mAbs IB4 and 60.3 released H2O2; H2O2 release did not occur when neutrophils were plated in wells coated with an irrelevant, isotype-matched mAb (OKDR), or with mAbs against other molecules (CD16, beta 2-microglobulin) expressed on the neutrophil surface at the same density of CD18. Four different mAbs, OKM1, OKM9, OKM10, 60.1, which recognize distinct epitopes of CR3 were unable to trigger H2O2 or O2- release from neutrophils. However, mAbs against LFA-1 or gp150/95 triggered both H2O2 and O2- release from neutrophils. Stimulation of neutrophils respiratory burst by both anti-CD18, and anti-LFA-1 or gp150/95 mAbs was totally inhibited by the microfilaments disrupting agent, cytochalasin B, and by a permeable cAMP analogue. While the capability to activate neutrophil respiratory burst was restricted to anti-LFA-1 and gp150/95 mAbs, we observed that mAbs against all members of leukocyte integrins, including CR3, were able to trigger neutrophil spreading. These findings indicate that, in neutrophils, all three leukocyte integrins can generate signals activating spreading, but only LFA-1 and gp150/95 can generate signals involved in activation of the respiratory burst. This observation can be relevant to understand the mechanisms responsible for the activation of neutrophil respiratory burst by tumor necrosis factor-alpha, which has been shown to be strictly dependent on expression of leukocyte integrins (Nathan, C., S. Srimal, C. Farber, E. Sanchez, L. Kabbash, A. Asch, J. Gailit, and S. Wright. 1989. J. Cell Biol. 109:13411349.

Antibodies, Monoclonal↗
PubMed1992

The effect of intermittent exposure to cold on the development of hypertension in the rat.

Continuous exposure to a cold (5 degrees C) environment has been shown to induce hypertension in rats. The total time required for the first significant elevation of blood pressure is dependent on a number of factors, including the ambient temperature and the weight of the rat at the time of exposure to cold. The present study was also concerned with the minimal time of daily exposure to cold that would result in a significant elevation of blood pressure. To achieve this, we used four groups of rats. One was exposed to cold for 4 h daily (09:00 to 13:00), a second group was exposed to cold for 8 h daily (09:00 to 17:00), and a third was exposed for 24 h daily. The fourth group remained at 25 degrees C. Systolic blood pressures of the group exposed to continuous cold became elevated significantly above pre-cold exposure level within 2 weeks of cold exposure. Blood pressures of the groups exposed to cold for 4 and 8 h daily became elevated significantly above the level of the warm-adapted control group by day 27 of exposure to cold, but failed to reach the level of the chronically cold-exposed group even after 42 days of exposure to cold. There was a sigmoid-type relationship between the hours per day exposed to cold and systolic blood pressure at the end of the experiment. Thus, graded elevations of systolic blood pressure occur with increasing daily duration of exposure to cold.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Translational modulation in hepatitis B virus preS-S open reading frame expression.

A series of hepatitis B virus open reading frame (ORF) preS-S variants, including mutants in which the relative order of the in-frame start codons (AUG1, AUG2 and AUG3) and nearby sequences had been altered, was expressed both in vivo (in HepG2 hepatoblastoma cells) and in vitro (by T7 promoter-driven transcription followed by translation in a rabbit reticulocyte lysate). The ratio of the synthesis of the large, middle (M) and major (S) proteins or their chimeric counterparts was analysed to study the translational regulation of ORF expression. As expected on the basis of the ribosome scanning model, the AUG sequence context was found to be a prominent factor in determining the different translational behaviour of the two preS-S-specific mRNAs of 2.4 kb (predominantly translated from AUG1) and 2.1 kb (which includes AUG2 and/or AUG3 and can be translated from either). Results from both experimental systems suggested that initiation at internal AUGs in the 2.4 kb RNA is possible. In experiments in vitro, preS-S mutants bearing lesions in a region 5' to AUG2, which has been implicated in AUG2/AUG3 cis repression, showed no increase in the utilization of internal AUGs. In addition, the chimeric envelope polypeptides produced in transfected HepG2 cells in this study were informative with respect to preS-mediated endoplasmic retention: replacement of the preS2 N terminus with that from preS1 generated a chimeric M protein that was glycosylated within the putative preS1 retention sequence ad was not secreted. Thus, the preS1 retention sequence most likely acts inside the lumen of endoplasmic reticulum and its function is insensitive to glycosylation. A similar element might be active at the N terminus of M protein.

Base Sequence↗
PubMed1992

Responsiveness and sensitivity to cholinergic agonists and antagonists in bovine isolated bronchial muscle.

1. Airways derived from different levels of the lung exhibit a difference in the reactivity and sensitivity to agonists. We have evaluated the effect of acetylcholine and cholinergic selective (pirenzepine, gallamine and 4-dipherylacetoxymethyl piperidine [4-DAMP]) and non-selective (atropine) antagonists on bovine proximal and distal smooth muscle preparations. 2. The distal preparations are more sensitive to acetylcholine than proximal bronchi. The relaxant effect of three selective antagonists on the distal and proximal tissues was the same when the results for each drug were compared. 3. Atropine and 4-DAMP were more potent than pirenzepine and gallamine in relaxing both proximal and distal bovine smooth muscle preparations. 4. These data suggest that the muscarinic sites on the smooth muscle of bovine airways are of the M3 subtype.

Acetylcholine↗