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Biomedical subjects

F Rossi

Publications and source records attributed to F Rossi.

At least 289 records · Page 16Linked to original sources
PubMed1996

[Heart surgery, cardiopulmonary bypass, and organic inflammatory response. Part II: changes in leukocytes, arachidonic acid derivatives, and hormones].

The use of cardiopulmonary bypass for surgical cardiac procedures is characterized by a whole-body inflammatory reaction due to the contact of blood through nonendothelialized surfaces; this stimulates the organism to recognize the cardiopulmonary bypass system as "nonself" and to activate specific (immune) and nonspecific (inflammatory) responses. These responses are then related with postoperative damage to many body systems of the body, like pulmonary, renal or brain dysfunction, excessive bleeding and postoperative sepsis. In this paper, present knowledge on untoward responses of the patient to cardiopulmonary bypass in cardiac surgery is reviewed and discussed, particularly focusing on the perturbation of the leukocytes, of the hormones and of the products of the arachidonic acid cascade.

Arachidonic Acids↗
PubMed1996

Antiarrhythmic effects of LR-A/113 a new calcium antagonistic drug.

LR-A/113 is a benzothiazepine drug similar to diltiazem with Ca(2+)-antagonist properties. Our previous studies showed that LR-A/113 determines anthypertensive effects comparable to diltiazem in normotensive and hypertensive rats. The aim of this study is to determine LR-A/113 effects respect to verapamil and diltiazem on CaCl2, aconitine and ouabain arrhythmias. Experiments were carried out on normotensive anesthetized rats and guinea pigs treated with CaCl2, aconitine and ouabaine and pretreated or not with verapamil, diltiazem or LR-A/113. Verapamil, diltiazem and LR-A/113, significantly delayed onset of arrhythmias and cardiac standstill induced by CaCl2 and aconitine. Moreover, pretreatments with verapamil, diltiazem or LR-A/113 reduced occurrence of arrhythmias in animals. In our models of arrhythmias LR-A/113 showed a significant antiarrhythmic effect of a magnitude almost similar to diltiazem but lower than for verapamil.

Aconitine↗
PubMed1996

[Effects of hyperbaric oxygenation in skin and pulmonary infections caused by Pseudomonas aeruginosa].

About 80% of nosocomial infections are caused by aerobic bacteria. The Pseudomonas aeruginosa is a Gram-negative bacterium pertaining to the Pseudomonadaceae family. P. aeruginosa is responsible for 6-22% of all hospital infections. The aim of this paper is to evaluate the efficacy of both hyperbaric oxygen-therapy (HBO 2 Atm x 35 min/day) alone for 8 days and when associated to the chemoantibiotic therapy (amikacine 15 mg/kg/day for 8 days intraperitoneal), in rats infected through pulmonary and subcutaneous intake. In rats affected by P. aeruginosa, HBO induces a significant reduction in mortality and morbility with bacteria eradication in blood culture findings, bronchial aspirate and skin biopsies. These effects were increased by the use of amikacine which is an antibiotic used for the treatment of Gram-negative bacteria.

Amikacin↗
PubMed1996

[The therapy of arterial hypertension: a comparison between ACE inhibitors and angiotensin-II-receptor antagonists].

The efficaciousness of ACE inhibitors in arterial blood hypertension is well known. These drugs decreased the incidence of hypertension and myocardial infarction in population. However, they increase tissue levels of some kinines, that may be responsible of some adverse reactions (cough, etc.). Angiotensin-receptor antagonists can minimize the adverse reactions due to kinine accumulation and may increase the safety of the antihypertensive drug-treatment. Pharmacological and clinical aspects of angiotensin-receptor antagonists are discussed.

Angiotensin Receptor Antagonists↗
PubMed1995

Characterization of human DNA ligase I expressed in a baculovirus-insect cell system.

The baculovirus expression system was used to overexpress human DNA ligase I (hLig I). Approx. 2 mg of recombinant hLig I was produced per 10(8) Spodoptera frugiperda Sf9 insect cells infected with the recombinant baculovirus. The optimum time point for the production of biologically active recombinant hLig I was 48 h post-infection. Lig I activity was demonstrated by auto-adenylating, polynucleotide joining and DNA relaxation assays. The baculovirus system has the advantage over previously described methods for producing hLig I of generating large amounts of a full-length active protein.

Animals↗
PubMed1995

Metabotropic and ionotropic glutamate receptors mediate opposite effects on periaqueductal gray matter.

Microinjections, into the dorso-lateral periaqueductal gray matter, of N-methyl-D-aspartic acid (NMDA, 0.07-7 nmol/rat) significantly (P < 0.01) increased arterial blood pressure in a dose-related manner. Pretreatment, 5 min before NMDA (7 nmol/rat), in the same area with 2-amino-5-phosphonovaleric acid (2-APV, 5 nmol/rat), a selective antagonist of NMDA receptors, significantly (P < 0.01) reduced NMDA-induced arterial hypertension. trans-(+/-)-1-Amino-1,3-cyclopentanedicarboxylic acid (t-ACPD, 6-30 nmol/rat), an agonist of metabotropic glutamate receptors (mGlu receptors), significantly (P < 0.01) decreased arterial blood pressure when microinjected into the dorsal-lateral periaqueductal gray matter. Pretreatment, 5 min before t-ACPD (30 nmol/rat), in the same area with L-2-amino-3-phosphono-propionate (L-AP-3, 30 nmol/rat), a putative antagonist of the mGlu receptors, was not able to prevent t-ACPD-induced hypotension. Microinjections of L-AP-3 (30 nmol/rat) induced a hypotension similar to the one obtained with t-ACPD at the dose of 6 nmol/rat. From these data we can suggest that mGlu receptors act inversely to the NMDA receptors in the dorso-lateral periaqueductal gray area and that L-AP-3 is a partial agonist rather than an antagonist of mGlu receptors within the periaqueductal gray area.

2-Amino-5-phosphonovalerate↗
PubMed1995

Pupillary and cardiovascular responses to the cold-pressor test.

Little is known about the structures and mechanisms involved in the autonomic response to sensory and nociceptive stimulation. In this study, we recorded simultaneously pupil diameter, blood pressure, heart rate and pain levels during a cold-pressor test in 10 healthy subjects. The aim was to evaluate the different components of the Autonomic Nervous System involved in the response to a thermal-painful stimulus. A biphasic pupillary response was observed: an initial, short-lasting mydriasis, followed by a miotic phase, this latter characterized by rhythmic fluctuations of pupil diameter. The blood pressure response was monophasic with a moderate increase observed from the second minute of the test. Pain intensities remained stable on medium-high levels throughout the test. The topical application of thymoxamine and homatropine clarified some aspects of the pupillary response. The systemic administration of naloxone suggested a role of opiates in the modulation of pupillary and cardiovascular response to the cold-pressor test.

Administration, Topical↗
PubMed1995

Role of 55- and 75-kDa TNF receptors in the potentiation of Fc-mediated phagocytosis in human neutrophils.

Human neutrophils respond with an increased phagocytosis when exposed to TNF. Two types of TNF receptors have been identified, namely 55 kDa (TR55) and 75 kDa (TR75). We addressed the problem of the role of these receptors in the priming effect of TNF. By using monoclonal antibodies (MoAbs) directed either against TR55 or TR75, we have shown that 1) only TR55 is the signaling receptor for the potentiation of Fc-mediated phagocytosis and upregulation of beta 2-integrin CD11b/CD18; 2) TR75 may control the function of TR55 by regulating the binding of TNF to the signaling receptor.

Antibodies, Monoclonal↗
PubMed1995

Differential regenerative response of Purkinje cell and inferior olivary axons confronted with embryonic grafts: environmental cues versus intrinsic neuronal determinants.

Regeneration of severed central axons is supposed to depend on two factors: a permissive local environment and the particular intrinsic properties of axotomized neurones. To assess the role of each of these factors in axonal regeneration, the capability of two particular axon populations of the adult mouse cerebellum to grow into target-specific (cerebellum) and target-unspecific (neocortex) embryonic grafts was determined. Purkinje cell and inferior olivary axons were transected by passing a microscalpel through the axial white matter of the cerebellar folia, particularly those of the anterior lobe. Immediately after the injury, solid transplants were placed in the lesion cavity. Purkinje cell axons were labelled by using anticalbindin immunocytochemistry, and olivocerebellar fibres were visualized by biotinylated dextran amine anterograde axonal tracing. Following axotomy, Purkinje cell axons appeared as thickened processes ending with large terminal clubs. Their morphology and number did not change up to the longest survival time considered (2 months), thereby confirming previous demonstrations that Purkinje cells survive axon injury (I. Dusart and C. Sotelo, 1994, J. Comp. Neurol. 347:211-232). Inferior olivary axons were thinner and bore smaller terminal bulbs. When embryonic cerebellar grafts, containing cortical and deep nuclear precursors, were placed close to the injured axons, olivocerebellar fibres vigorously regenerated into the transplants and ended in new climbing fibres along the dendrites of grafted Purkinje cells. By contrast, host Purkinje cell axons never showed any outgrowth towards the graft. Similarly, these axons failed to regenerate into grafts containing solely the rostromedial portion of the cerebellar anlage, mostly consisting of deep nuclear neurones, their main targets. Comparable results were obtained by transplanting embryonic neocortical tissue: inferior olivary axons also regenerated into the grafts, although with distinct terminal arbours without the climbing fibre phenotype, whereas Purkinje cell axons always failed to grow. These results provide the first direct demonstration that severed inferior olivary axons are able to regenerate. In addition, they show that the growth-permissive/-promoting conditions created by embryonic nervous tissue are not sufficient to induce the regeneration of every axonal type and allow us to hypothesise that successful regeneration depends on the interplay between environmental cues and intrinsic properties of the axotomized neurones.

Animals↗
PubMed1995

alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionate receptors modulate dopamine release in rat hippocampus and striatum.

The effects of infusing the glutamate receptor agonist alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) on the release of dopamine (DA) has been studied in rat hippocampus and striatum in vivo. In hippocampus, AMPA (1-10 microM) produced a dose related increase in dialysate DA, but at 100 microM AMPA a sustained decrease in extracellular DA was observed. However, when samples were collected at 5-min intervals 100 microM AMPA infusion revealed a brief increase in hippocampal dialysate DA. Infusion of 100 microM AMPA and 500 microM diazoxide, which blocks AMPA receptor desensitization, led to a marked increase in extracellular DA, as did diazoxide alone, although to a lesser extent. The AMPA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3,-dione (CNQX; 200 microM) reversed the effect of AMPA and/or diazoxide infusion on dialysate DA and when infused alone, CNQX also decreased hippocampal dialysate DA. AMPA (50-500 microM) increased striatal DA release. The effect of AMPA on extracellular DA was reversed by CNQX (200 microM). Diazoxide infusion caused a decrease in striatal DA release, and this was not affected by CNQX. These data suggest that hippocampal, but not striatal AMPA receptor desensitization may play a role in regulating DA release.

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMed1995

Disruption of base-paired U4.U6 small nuclear RNAs induced by mammalian heterogeneous nuclear ribonucleoprotein C protein.

Due to 3' end modifications, mammalian U6 small nuclear RNA (snRNA) is heterogeneous in size. The major form terminates with five U residues and a 2',3'-cyclic phosphate, but multiple RNAs containing up to 12 U residues have a 3'-OH end. They are labeled in the presence of [alpha-32P]UTP by the terminal uridylyl transferase activity present in HeLa cell nuclear extracts. That these forms all enter the U6 snRNA-containing particles, U4.U6, U4.U5.U6, and the spliceosome, has been demonstrated previously. Here, we report an interaction between the heterogeneous nuclear ribonucleoprotein (hnRNP) C protein, an abundant nuclear pre-mRNA binding protein, and the U6 snRNAs that have the longest uridylate stretches. This U6 snRNA subset is free of any one of the other snRNPs, since anti-Sm antibodies failed to immunoprecipitate hnRNP C protein. Furthermore, isolated U4.U6 snRNPs containing U6 snRNAs with long oligouridylate stretches are disrupted upon binding of hnRNP C protein either purified from HeLa cells or produced as recombinant protein from Escherichia coli. In view of these data and our previous proposal that the U6 snRNA active in splicing has 3'-OH end, we discuss a model where the hnRNP C protein has a decisive function in the catalytic activation of the spliceosome by allowing the release of U4 snRNP.

Base Composition↗
PubMed1995

Different climbing fibres innervate separate dendritic regions of the same Purkinje cell in hypogranular cerebellum.

Electrophysiological experiments have shown that in hypogranular cerebella the Purkinje cells are innervated by several climbing fibres. The aim of this paper is to provide morphological evidence for this multiple innervation and to describe the topographical distribution of the different climbing fibres onto the somadendritic region of the Purkinje cell. Experiments have been performed in hypogranular adult Wistar rats lesioned during the first postnatal week by methylazoxymethanol (MAM) or by X-irradiation. Purkinje cells were labelled by an anti-calbindin antibody, whereas climbing fibres were visualised by means of Phaseolus vulgaris leucoagglutinin. Purkinje cells showed variable degrees of abnormality and displacement. Climbing fibres made contact with the dendrites of all kinds of Purkinje cells, including those ectopically positioned whose dendrites branched in the white matter. This shows that Purkinje cells can develop dendritic branching in the absence of granule cells and maintain the capability of interacting with their proper afferents, even when they are severely affected and displaced. In four Purkinje cells we have been able to follow the course of two climbing fibre terminal arbourisations. Almost no terminal branches were present around the Purkinje cell soma, and the whole arbour covered the proximal two-thirds of the Purkinje cell dendritic tree. These arbourisations, after an initial common course along the primary dendrite, distributed to separate dendritic regions. The observation of a single labelled climbing fibre covering a limited region of the dendritic tree was more common. As this finding is never observed in control material, it is concluded that the remaining region is covered by another unlabelled climbing fibre belonging to a different inferior olive neurone. These results represent a morphological demonstration of multiple climbing fibre innervation of the adult Purkinje cell. The maintenance of polyinnervation in the adult, which is consequent to the loss of granule cells, is not associated with a defect in the peridendritic translocation of the olivary arbour. In addition, the strict segregation of the different climbing fibres to distinct territories of the Purkinje cell dendritic tree suggests that each terminal arbourisation acts as a functionally independent unit and prevents other competitors from invading its own target domain.

Afferent Pathways↗
PubMed1995

Mechanisms of NADPH oxidase activation in human neutrophils: p67phox is required for the translocation of rac 1 but not of rac 2 from cytosol to the membranes.

NADPH oxidase is the enzyme complex responsible for the production of oxygen radicals in phagocytes. On neutrophil stimulation, the cytosolic components of NADPH oxidase, p67phox and p47phox, as well as the Ras-related G-protein rac 2, are translocated from the cytosol to cell membranes where they associate with a flavocytochrome b to form a functional complex. Besides rac 2, rac 1 G-protein is also involved in the activation of the NADPH oxidase, but, to date, it has not been documented whether it is also translocated in activated neutrophils. In this paper we show that: (a) in neutrophils stimulated with formylmethionyl-leucylphenylalanine, concanavalin A or phorbol 12-myristate 13-acetate, both rac 1 and rac 2 are translocated from cytosol to the membranes; (b) in neutrophils from a patient with a form of chronic granulomatous disease in which p67phox is absent, rac 2 and p47phox were translocated as in normal neutrophils on stimulation with the above agonists, but rac 1 failed to be translocated from the cytosol to the membranes. This is the first demonstration that, in activated neutrophils, rac 1 is translocated from the cytosol to the membranes and this translocation requires p67phox. These results, coupled with those showing that rac 2 is not translocated in activated neutrophils lacking p47phox [El Benna, Ruedi and Babior (1994) J. Biol. Chem. 269, 6729-6734], may suggest that the assembly of the cytosolic components of NADPH oxidase on the plasma membrane takes place through selective coupling of activated rac 1 and rac 2 with p67phox and p47phox respectively.

Blotting, Western↗
PubMed1995

[Aib5,6-D-Ala8]-cyclolinopeptide A, grown from a benzene/acetonitrile mixture.

cyclo-(Prolyl-prolyl-phenylalanyl-phenylalanyl- alpha-aminoisobutyryl-alpha-aminoisobutyryl-isoleucyl-D-alan yl-valyl) ([Aib5,6-D-Ala8]-cyclolinopeptide A), grown from benzene/acetonitrile mixture, crystallizes with one acetonitrile and two water molecules. The molecular structure is almost identical to that obtained from methanol/water. The dimension of the solvent channels found in these structures is reduced in the present one, but the intramolecular hydrogen-bond pattern is preserved. The Pro1-Pro2 peptide unit is cis (omega = 8 degrees); all others are trans.

Acetonitriles↗