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Biomedical subjects

G Cavallo

Publications and source records attributed to G Cavallo.

At least 37 records · Page 2Linked to original sources
PubMed1994

Presence of murine retroviral sequences in human cell line transplanted in immunosuppressed SCID-mice.

The SCID-hu mouse, a severe combined immunodeficient mouse transplanted with human hematopoietic cells, has been proposed as an experimental model for HIV-1 infection. However, like other animal models for infectious diseases, the SCID-hu mouse should provide the replication of the experimental agent without conferring any alteration during growth in the host. In this study using Southern blot hybridization, in situ hybridization and PCR analysis we demonstrate the presence of specific murine retroviral sequences in human cells recovered from the in vivo passages in SCID mice. Since the acquisition of endogenous retrovirus by human cells was demonstrated after their growth in nude mice, the data reported here extend this observation to the SCID model.

Animals↗
PubMed1994

[Videoproctography in the study of rectal intussusception. The authors' own experience].

Videoproctography has proved to be a useful diagnostic technique to investigate anorectal disorders; it can provide morphological and functional information which no other diagnostic method yields. From a series of 898 videoproctographs, the findings of 117 patients with rectal intussusception were retrospectively reviewed. The most common symptoms were an incomplete emptying feeling (93% of cases), obstructed defecation (78%), and a feeling of upright rectal weighting (71%). Of the three known types of rectal intussusception, the most common type was distal intussusception (44%), followed by the rectoanal type (38%) and finally by the proximal type (19%). The three types of intussusception were frequently (42%) associated with other disorders of rectal ampulla and especially with rectocele (15%), mucosal prolapse (8%), and descending perineum syndrome (12%); they had different clinical correlations and proctographic patterns and could be recognized in different defecation phases. In our personal experience, proctography with videorecording was a useful diagnostic tool in the dynamic assessment of this morphofunctional disorder which represents one of its major indications.

Adult↗
PubMed1993

Preparation and characterization of four new variously deacetylated lysogangliosides, breakdown products of GM1.

Four new deacylated lysogangliosides were obtained through alkaline hydrolysis of either C18 or C20 sphingosine homologues of GM1. By this procedure, both the fatty acids residue and the N-acetyl group of sialic acid were removed to give mono-N-acetyl-lysoGM1 (C18 and C20); the additional loss of the N-acetyl group of the acetylgalactosamine moiety gave de-N-acetyl-lysoGM1 (C18 and C20) with three free amino groups. The structures of four deacetylated lysogangliosides were unambiguously characterized by chemical analysis and 1H and 13C NMR spectroscopy as well as by negative ion FABMS. The aim of this study was to isolate pure breakdown products of gangliosides, enabling the evaluation of the mechanism of action of glycosphingolipids through their cleavage and identification of structures of potential pharmacological activity. These new substances were prepared as candidates to influence eicosanoid production and the mechanisms dependent on protein kinase C and phospholipase A2.

Animals↗
PubMed1993

Antiplatelet effects of a new de-N-acetyl-lyso-glycosphingolipid.

Gal beta 1-->3GalN beta 1-->4Gal(3<--2 alpha Neu)beta 1-->4Glc beta-->1Sph (WILD20), a new glycosphingolipid, a breakdown product of the monosialoganglioside GM1 obtained through alkaline hydrolysis, shows dose-dependent platelet anti-aggregating properties in vitro and in vivo. This effect is agonist- and species-independent. The family of lysosphingolipids, to which the compound belongs, is present in platelets particularly after thrombin treatment. WILD20 antiplatelet effect is due to the interference with ADP or thrombin-induced aggregation, probably via phospholipase A2 (PLA2) blockade; the substance is also effective when arachidonic acid is used as an agonist. Serotonin blood levels are also reduced. The substance, orally active at dosages of 0.1-0.01 mg/kg as antiplatelets agent, prolonged bleeding time without interfering with the coagulative or fibrinolytic processes.

Animals↗
PubMed1993

Involvement of phospholipase A2 activation and arachidonic acid metabolism in the cytotoxic functions of rat NK cells.

Arachidonic acid (AA) release via phospholipase A2 (PLA2) activation and generation of eicosanoids have been implicated as playing signaling roles in a variety of cell types. Here we show evidence that interaction of fresh NK cells with membranes from sensitive or antibody (Ab)-coated targets generates eicosanoids through both cyclooxygenase (CO) and lipoxygenase (LO) pathways. Eicosanoid generation is attributable to PLA2 activation since pretreatment with PLA2 irreversible inhibitors, such as mepacrine or para-bromophenacylbromide (pBPB), completely blocks AA metabolite generation. The involvement of PLA2 or AA metabolites in the cytotoxic functions of rat NK cells has also been investigated. Treatment of effector cells with mepacrine or pBPB resulted in complete, irreversible, dose-dependent inhibition of both NK and ADCC activities, which were completely reversed by the addition of exogenous PLA2 or its hydrolysis products, AA and lysophosphatidylcholine (lysoPC). Among the metabolites of AA released by NK cells, the 5-LO product leukotriene B4 (LTB4) seems to play an important role in cytolytic activities of NK cells. Indeed, the LO inhibitor, nordihydroguaiaretic acid (NDGA), totally abrogated both NK and ADCC activities, which were restored by the addition of exogenous LTB4. However, the failure of LTB4 to reverse mepacrine or pBPB-induced inhibition of NK and ADCC suggests that its effects could be mediated by PLA2. The results are consistent with a crucial role for the target-stimulated AA release as a fundamental step in the signal transduction pathway in NK cell. Moreover, LTB4 generation seems to be responsible for further PLA2 activation in a second step leading to the amplification of response.

Animals↗
PubMed1993

Effect of a new de-N-acetyl-lysoglycosphingolipid on chemically-induced inflammatory bowel disease: possible mechanism of action.

A new, orally active de-N-acetylated lysoglycosphingolipid (WILD20) was evaluated as antiinflammatory agent using a model of chemically-induced inflammatory bowel disease (IBD) in the rat to mimic human ulcerative colitis and Chron's disease. IBD was induced by hapten trinitrobenzenesulphonic acid (TNB). WILD20, orally administered as preventive or curative, was demonstrated to be efficacious at daily dosages of 0.1-1 mg/kg for 4-5 days. Damage scores, body weight, spleen weight, colonic tissular levels of LTB4, myeloperoxidase (MPO) and malondialdehyde (MDA) are influenced and brought into parameters of normality. Histological observation demonstrated quicker healing, better repair, reduced inflammation, and poor eosinophil degranulation. The mechanisms underlying WILD20 antiinflammatory effects were investigated: whereas WILD20 fails to show a direct effect on PKC, it reduces PKC translocation to the membrane; cellular PLA2 was consequently greatly reduced through this mechanism and thought to be responsible for WILD20 efficacy towards chemically-induced IBD.

Animals↗
PubMed1993

Functional intraperineal pouch of rectal wall (posterior rectocele).

We have identified 18 cases of functional pouch of the posterior rectal wall visualized by defecography. In the absence of previous evidence in the literature, we named this anomaly "posterior rectocele" and studied it from the clinical, radiologic, and endoscopic points of view.

Adult↗
PubMed1992

Impaired transcription of the poly rI:rC- and interferon-activatable 202 gene in mice and cell lines from the C57BL/6 strain.

Activation of 202 and (2'-5')(A)n synthetase genes after injection of interferon (IFN)-inducing, double-stranded, poly rI:rC was compared in various mouse strains. The 202 mRNA level increased 4.5- to 10-fold in DBA/2, BALB/c, and C3H/HeJ mice, whereas in C57BL/6 mice it rose only to about that in untreated DBA/2, BALB/c, and C3H/HeJ mice. To determine whether this low level was due to a reduced transcription rate, a nuclear "run-on" assay was performed with NIH 3T3 cells or BLK cells derived from C57BL/6 mice. IFN-alpha increased the 202 mRNA transcription severalfold in NIH 3T3 cells only, and that of a (2'-5')(A)n synthetase gene in both cell lines. The possibility that an alteration in transacting factors could be responsible for this difference was examined. For this purpose the 5' terminal flanking region (called the b segment, about 0.8 kb) of the 202 gene was linked to a heterologous reporter gene--chloramphenicolacetyl-transferase (CAT) and transfected into normal or transformed NIH 3T3 cells and into various C57BL/6-derived cell lines. IFN-alpha induced strong CAT activity in transfected normal or transformed NIH 3T3 cells, but a much lower activity in those from C57BL/6 mice. The b segment contains an IFN-responsive element (ISRE) (35 bp) homologous to that present in several other IFN-inducible genes. Three tandem copies of the 202 ISRE were linked to an enhancerless SV40 early promoter driving an influenza virus hemagglutinin (HA) cDNA segment. No increase in HA mRNA expression was detected in the transfected BLK cell line derived from C57BL/6 mice following IFN treatment, whereas in the NIH 3T3 cell line, the IFN treatment resulted in a 2.5-fold increase. These and other results suggest that C57BL/6 mice and cell lines derived from them might carry defective transacting factors impairing the ability of IFN-alpha to activate the 202 gene without impairing its ability to activate a (2'-5')(A)n synthetase gene.

2',5'-Oligoadenylate Synthetase↗
PubMed1992

Demonstration of the formation of hydroxyl radicals in acute myocardial infarction in man using salicylate as probe.

Dihydroxybenzoic acid (DHBA) derivatives of acetylsalicylic acid (ASA) are formed in vivo by the action of the hydroxyl radical (OH.). In order to evaluate the possible formation of OH(.) in acute myocardial infarction (AMI) in man, 9 consecutive patients with a first episode of AMI (8 males, 1 female, mean age 50.3 years), treated with rt-PA, and 8 healthy volunteers (7 males, 1 female, mean age 29.8 years) were studied. All subjects received 100 mg ASA p.o. daily; venous blood samples were taken 30 min after the first dose (time 0) and then at 3-, 6-, 12-, 24- and 48 h and 5 days. Serum was analyzed by HPLC and electrochemical detection for 2,3- and 2,5-DHBA contents. 2,3-DHBA was present in all subjects with AMI and undetectable in healthy volunteers at all time points studied. Serum levels of 2,5-DHBA did not show statistically significant differences between AMI patients and healthy volunteers. These data support the hypothesis that hydroxyl radicals are formed during AMI in man.

Aspirin↗
PubMed1992

Effects of interferon alpha on murine cytomegalovirus replication.

The present study examined the protective effect of IFN-alpha against mouse cytomegalovirus (MCMV) infection in embryo fibroblasts (MEF) of genetically resistant (C3H/HeJ) and susceptible (C57BL/6) mouse strains. At a M.O.I. of 1 IFN-alpha was protective in C3H/HeJ-MEF but not in C57BL/6-MEF. Dot-blot analysis during MCMV replication in C3H/HeJ-MEF showed that IFN-alpha pretreatment reduced the steady state level of immediate early and late mRNAs but partially reduced early gene expression.

Animals↗
PubMed1991

Activation of interferon-inducible genes in mice by poly rI:rC or alloantigens.

We have examined the effects of synthetic dsRNA (poly rI:rC) treatment or of immunization with irradiated allogeneic cells on the expression in vivo of several interferon (IFN)-inducible genes. For this purpose, DBA/2 mice were injected i.p. once with poly rI:rC, or once and then again 3 weeks later, with irradiated C3H/He spleen cells and the effect of these treatments on the levels of the following mRNAs was determined: 202, 2',5'-oligoadenylate synthetase (2-5A synthetase), class I and class II major histocompatibility antigens, and beta-actin. After poly rl:rC treatment, the levels of the 202 and 2-5A synthetase mRNAs in the spleen and in the bone marrow peaked between 12 and 24 h and decreased thereafter. The class I mRNA levels started to increase at 12 h, peaked at 24 h, and declined thereafter. No increase in class II mRNA expression was observed after poly rl:rC injection, whereas beta-actin levels remained unchanged. Pretreatment of DBA/2 mice with sheep anti-murine IFN-alpha/beta antibodies before poly rI:rC injection strongly diminished the induction of 202 mRNA, indicating that IFN-alpha/beta mediated this induction. When irradiated C3H/He spleen cells were injected into DBA/2 mice, the class I and class II mRNAs in the spleen, but not in the bone marrow, started to increase at 12 h, peaked between 48 and 96 h, and decreased thereafter. No increase in the levels of 202 and 2-5A synthetase mRNAs was detected, whereas beta-actin levels remained unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)

2',5'-Oligoadenylate Synthetase↗
PubMed1991

Interferon action: binding of viral RNA to the 40-kilodalton 2'-5'-oligoadenylate synthetase in interferon-treated HeLa cells infected with encephalomyocarditis virus.

The 40-kDa 2'-5'-oligoadenylate [(2'-5') (A)n] synthetase isoenzyme was proven to be a mediator of the inhibition of encephalomyocarditis virus (EMCV) replication by interferon (IFN). When activated by double-stranded RNA, this enzyme converts ATP into 2'-5'-oligoadenylate [(2'-5') (A)n], and (2'-5') (A)n was found to accumulate in IFN-treated, EMCV-infected cells. The only known function of (2'-5') (A)n is the activation of RNase L, a latent RNase, and this was also implicated in the inhibition of EMCV replication. Intermediates or side products in EMCV RNA replication, presumed to be partially double stranded, were shown to activate (2'-5') (A)n synthetase in vitro. These findings served as the basis of the long-standing hypothesis that the activator of (2'-5') (A)n synthetase in IFN-treated, EMCV-infected cells is the viral RNA. To test this hypothesis, we have generated a polyclonal rabbit antiserum to the human 40-kDa (2'-5') (A)n synthetase. The antiserum immunoprecipitated, from IFN-treated HeLa cells that had been infected with EMCV, the 40-kDa (2'-5') (A)n synthetase protein in complex with both strands of EMCV RNA. The immunoprecipitate was active in (2'-5') (A)n synthesis even without addition of double-stranded RNA, whereas the immunoprecipitate from IFN-treated, uninfected cells was not. These and other results demonstrate that in IFN-treated, EMCV-infected cells, viral RNA is bound to the (2'-5') (A)n synthetase and suggest that the agent activating the (2'-5') (A)n synthetase is the bound viral RNA.

2',5'-Oligoadenylate Synthetase↗
PubMed1991

In-vitro interaction of cephalosporin and the immune system.

In this study we have evaluated the effects of an antibiotic, such as cefonicid, on some immune reactivities in vitro. The following immune parameters have been analyzed: i) interferon-gamma and interleukin-2 production and ii) lymphocyte proliferation following mitogen stimulation in the presence of cefonicid concentrations ranging from 50 to 500 microg/ml. No. decrease in lymphokine production in the presence of cefonicid concentrations up to 250 microg/ml was observed between untreated or antibiotic-treated lymphocyte cultures. When lymphocyte proliferation upon Con A stimulation, as evaluated by 3H-dHtd incorporation, was measured in the presence of cefonicid, no differences were observed with untreated controls. These results demonstrate that the in vitro interaction of cefonicid with the immune system does not lead to a decrease of the immune response.

Cefonicid↗
PubMed1991

Interactions of antibiotics with phagocytes in vitro.

The goal of antimicrobial therapy is to eliminate invading bacteria both in the extracellular and intracellular environment. Thus, recent work has focused on the ability of various antibiotics to enter phagocytic cells and kill intracellular pathogens, since bacteria which survive within phagocytes may often produce prolonged or recurrent infections. In the last ten years the antibiotic modulation of phagocytic cell functions has become the subject of our major investigational activity. Taking into account that entry of antibiotics into phagocytes is necessary for activity against intracellular organisms, we examined the uptake of 11 radiolabelled antibiotics by macrophages. Penicillins and cephalosporins were taken up poorly by phagocytes. Teicoplanin was efficiently concentrated by macrophages, achieving intracellular concentrations higher than those in the surrounding extracellular medium. Roxithromycin was more markedly accumulated within phagocytes than was erythromycin, depending upon an active transport mechanism. Antitubercular drugs were concentrated approximately twofold in the macrophages. Besides, since antibiotics that act on phagocytosed bacteria have clinical advantages, we evaluated the direct action of the above mentioned drugs on the macrophage, by determining their interference with its functions or their potentiation of both phagocytosis and killing of bacteria.

Anti-Bacterial Agents↗
PubMed1991

Activation of interferon-inducible genes in vivo by synthetic double-stranded RNA, poly rI:rC.

We analyzed the effects of synthetic dsRNA (poly rI:rC) treatment on the expression in vivo of two interferon (IFN)-inducible genes. DBA/2 mice were injected i.p. with poly rI:rC and its effect on the levels of the following mRNAs was determined; 202, 2'-5' oligoadenylate synthetase (2-5A synthetase) and beta-actin. After poly rI:rC treatment the levels of the 202 and 2-5A synthetase mRNAs in the spleen and in bone marrow peaked between 12 and 24 h and decreased thereafter, whereas beta-actin levels remained unchained unchanged. Pretreatment of DBA/2 mice with sheep anti-murine IFN-alpha/beta antibodies before rI:rC injection strongly diminished the induction of 202 mRNA indicating that IFN-alpha/beta mediated this induction.

Animals↗
PubMed1990

Cell and type specificity of interferon action. Unusual characteristics of the transcriptional control of gene expression by interferon-gamma in T cells.

We have examined the mechanisms by which interferon (IFN)-gamma and IFN-alpha regulate the expression of 2'-5'-oligoadenylate synthetase (2-5A synthetase) and class I major histocompatibility complex antigens in murine T cells and in cell types of other histological origin. When treated with IFN-alpha both fibroblasts and T cell lines displayed a marked increase of the 2-5A synthetase activity and of the corresponding mRNA. The augmentation of the enzyme activity in T cells was induced by IFN-alpha at the transcriptional level, as determined by nuclear run-on analysis. In contrast IFN-gamma was capable of increasing 2-5A synthetase activity only in fibroblasts, but not in T cells. Nuclear run-on assays revealed that the 2-5A synthetase gene in T cells is not transcriptionally activated by IFN-gamma. After IFN-alpha and -gamma treatment we also observed a significant increase in class I gene expression in fibroblasts and T cell lines as measured both on the cell surface and by cytoplasmic RNA accumulation. In the case of the T cell line, DO1110, the observed increase in the steady-state levels of class I transcripts was a consequence of a high rate of H-2 gene transcription as demonstrated by run-on analysis. However, the molecular mechanisms involved in this IFN-dependent H-2 gene transcriptional activation are different between IFN-alpha and IFN-gamma. When the T cell lines DO1110, L12-R4 and EL4 were transfected with a plasmid containing a reporter gene (chloramphenicol acetyltransferase) under the control of a regulatory IFN-responsive DNA element of 237 bp or 1.4 kb, IFN-alpha was able to activate the transcription of these constructs. In contrast, IFN-gamma did not recognize the IFN-responsive element which, by itself, activated transcription of the reporter gene in response to IFN-gamma in other cellular types of non-T cell origin. Therefore, in the T cell lines examined, IFN-gamma increases the H-2 gene expression by acting on DNA elements located upstream of the regulatory segment used in this study or downstream of the cap site. This suggests a possible cell specificity in the activation of an IFN-responsive element, that in turn may regulate the IFN-inducible gene expression in a cell-specific fashion. Thus, the differential biological activities of IFN-gamma on T cells could be generated by a differential gene activation at the transcriptional level.

2',5'-Oligoadenylate Synthetase↗
PubMed1990

Augmentation of mouse natural killer (NK) activity by GM-1/P, a processed form of monosialoganglioside GM-1.

We describe the immunomodulatory activity of GM-1/P a processed form of GM-1 (monosialoganglioside) extracted from ox brain, purified and physically modified. We examined the effect of in vivo and in vitro treatment of GM-1/P on natural (NK) activity and its ability to induce the production of interleukin-2 (IL-2) in the mouse. In vivo treatment with GM-1/P (1 mg/Kg, i.v., day-1) resulted in a marked increase and in a change of distribution of NK activity, which was associated with lower density Percoll fractions. Marked increase was already observed at 18 hrs and then declined by day 4. In vitro treatment with GM-1/P (2 micrograms/ml) enhanced NK activity of B6 spleen cells, already after 6 hours of incubation, remaining at plateau levels within 18 hours. A role of IL-2 in this enhancement was suggested by the ability of an anti-IL-2 rabbit antiserum to abolish in vitro increased cytotoxicity. The presence of IL-2 in the supernatants of splenocytes from GM-1/P (1mg/Kg, i.v., ,day-1) treated mice stimulated with Con A or Con A plus TPA for 48 hrs was evaluated by proliferation of an IL-2 dependent CTLL cell line. GM-1/P by itself was unable to stimulate IL-2 production; however it markedly increased IL-2 production induced by Con A or Con A plus TPA.

Adjuvants, Immunologic↗