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Biomedical subjects

M M de Bracco

Publications and source records attributed to M M de Bracco.

At least 19 recordsLinked to original sources
PubMed2001

Monocyte differentiation and HIV replication after prolonged culture of peripheral blood mononuclear cells from HIV-infected individuals.

Primary cultures of peripheral blood mononuclear cells (PBMC) from 51 HIV+ hemophiliac patients (HIV+ PBMC) were set up, allowing undisturbed cellular interaction in the absence of any exogenous stimuli. The optimum time for p24 detection was between 12 and 25 days. Infective virus was recovered from the culture supernatants (HIV+ SN) and the amount of p24 released ranged from 25 to 5300 pg/ml. Cells of the monocyte/macrophage (M/M) lineage were the main source of HIV in the HIV+ SN, as judged by intracellular staining of permeabilized cells with anti-p24 (KC57 monoclonal antibody) and flow cytometry analysis. M/M activation, differentiation, and proliferation occurred along the culture before the peak of in vitro HIV replication. Release of HIV p24 was highest in patients with >200 CD4+ T lymphocytes/mm3 who did not receive highly active antiretroviral therapy (HAART), but it was still detectable in 60-90% of patients who had responded to 1-2 years of HAART, reducing their plasma viral load to undetectable levels. It is proposed that this simple experimental system can be used to assess ongoing HIV infection of M/M with the patient's own viral variants.

Antiretroviral Therapy, Highly Active↗
PubMed2000

Nonhepatosplenic gamma delta T-cell lymphoma with initial testicular compromise.

We report here a case of nonhepatosplenic gammadelta T-cell lymphoma with undescribed initial localization in testis, without hepatosplenomegaly or adenopathies, and subsequent development in the maxillary sinus. The maxillar mass biopsy revealed a T-cell infiltration, and its immunologic characterization by flow cytometry showed a gammadelta T-cell phenotype (CD45+, CD3+, CD2+, TCR gammadelta+), without expression of CD7, CD5, CD1a, TdT, CD4, CD8, TCR alphabeta, or NK antigens (CD16, CD56, and CD57). Clonal gamma-chain gene rearrangement by polymerase chain reaction (PCR) was detected in testicular and maxillar biopsies. Epstein-Barr virus type 1 (EBV) sequences were detected by molecular biology in the biopsy material, suggesting that this oncogenic virus may play a role in the genesis of the clonal expansion of gammadelta T-cells. The patient was initially treated with standard chemotherapeutic protocols, with poor response and aggressive course.

Humans↗
PubMed1999

Tyrosine kinase regulatory action on ileal muscarinic effects of IFN-gamma.

Interferon-gamma (IFN-gamma) is a pleiotropic cytokine that has a large number of immunologic and nonimmunologic functions. We have described that IFN-gamma could activate muscarinic cholinergic receptors (mAchR) of rat intestine, stimulating ileal motility. We also observed that mAchR activation induced inhibition of cAMP levels and stimulation of cGMP formation. The objectives of our work were to clarify the signal transduction pathways involved in regulation of ileal motility through mAchR activation by IFN-gamma. Our results demonstrate that this cytokine produces an ileal cholinergic response through tyrosine kinase activity. The activation of tyrosine kinase mediates ileal contractility, phosphoinositide hydrolysis by phospholipase C, nitric oxide synthase via protein kinase C, and cGMP synthesis. The increment in ileal motility is probably due to hyperproduction of prostaglandin E2 (PGE2) by ileal tissue. This prostanoid is an important mediator because it stimulates ileal motility. We conclude that IFN-gamma not only immunomodulates the gut microenvironment but also exerts a local nonimmunologic regulation on intestinal motility.

Animals↗
PubMed1999

CD8 expression in a case of chronic lymphocytic leukemia with trisomy 12.

We report a case of B-cell chronic lymphocytic leukemia (B-CLL) with aberrant expression of the T-cell-associated antigen CD8, as revealed by two-color flow-cytometric analysis. DNA studies showed immunoglobulin heavy-chain gene rearrangement, but not of gamma-chain T-cell receptor, confirming the B-cell origin of the neoplastic cells. Ploidy analysis showed a tetraploid population and high S-phase fraction. B-CLL cells also carried trisomy 12, detected by fluorescence in situ hybridization. The identification of more cases with the same features would be necessary to establish the prognosis of this subtype of B-CLL.

Aged↗
PubMed1999

Protein kinase C regulates NO-cGMP pathway in muscarinic receptor activation by HIV+-IgA.

In this work we demostrate that IgA purified from HIV infected patients recognizes a band with a molecular weight corresponding to radiolabelled ileal muscarinic acethylcholine receptors (mAChR) by immunoblotting. HIV+-IgA triggers the signals that are the consequence of mAChR stimulation in the intestine, regulating protein kinase C (PKC) and nitric oxide synthase (NOS) activity as well as 3',5'-cyclic guanosine monophosphate (cGMP) formation. On the one hand PKC activation by HIV+-IgA induces NOS inhibition and as a consequence, low amounts of NO that could improve local immunosuppression in the intestine; on the other hand HIV+-IgA stimulates cGMP production which could potentiate ileal motility and loss of water/electrolytes involved in intestinal damage in AIDS.

Animals↗
PubMed1997

Macrophages, multinucleated giant cells, and apoptosis in HIV+ patients and normal blood donors.

Clearance of apoptotic debris is carried out by cells of the monocyte/macrophage lineage and, as other macrophage functions, it can be altered in AIDS, leading to the accumulation of apoptotic cells observed in this disease. In this study we evaluated the ability of macrophages from human immunodeficiency virus (HIV)-infected patients to differentiate and to clear apoptotic debris in prolonged in vitro cultures. Peripheral blood mononuclear cells (PBMC) from infected hemophilia patients were cultured in the absence of exogenously added stimulators and the organization and morphological characteristics of the cultures were analyzed and correlated with clinical staging of the patients. Cell aggregates of different sizes involving macrophages and lymphocytes were formed in cultures from asymptomatic HIV+ patients (CDC groups II-III) and controls and in 4/7 group IV C2 HIV+ patients. In order to obtain viable and organized cultures, cells had to be handled carefully, allowing contact and undisturbed sedimentation in round-bottom tubes. Multinucleated giant cells (MGC) were formed through macrophage fusion after 5 days of culture in HIV- controls, group II and III patients, and some of the group IV C2 patients, while scarce formation of MGC was observed in AIDS patients or patients with advanced HIV disease. This paucity was correlated with impaired dead cell removal and accumulation of apoptotic debris. Viability of macrophages and MGC was reduced after 15 days. MGC and the macrophages (either free or in cell aggregates) were able to remove dead cells, clearing the cultures of cell debris. Furthermore, in group II and III HIV+ hemophilic patients, increased macrophage-MGC phagocytic activity, suggesting in vivo activation, was frequently observed. In HIV+ patients with AIDS or advanced HIV disease (CDC groups IV A, IV C1, and IV D) dead cell removal was impaired and apoptotic debris accumulated. Long-term cultures of unstimulated PBMC are an interesting model for studying the role of macrophages and/or MGC in the removal of dead cells as well as examining the cellular milieu in which HIV replicates in an individual host.

Acquired Immunodeficiency Syndrome↗
PubMed1997

IgA from HIV+ haemophilic patients triggers intracellular signals coupled to the cholinergic system of the intestine.

IgA was obtained from HIV-infected haemophilic patients and the intracellular signals triggered by its reaction with isolated rat intestinal strips were studied. HIV+ IgA stained intestinal microvilli with a granular immunofluorescence pattern and bound to the muscarinic acetylcholine receptor (mAChR), displacing the specific muscarinic cholinergic antagonist QNB in a non-competitive manner. It triggered the signals that are the consequence of mAChR stimulation in the intestine. Thus, it decreased cAMP synthesis and increased guanosine 3':5'-cyclic monophosphate (cGMP) formation and phosphoinositide (PI) turnover of the intestine. In addition, it stimulated prostaglandin E2(PGE2) synthesis by intestinal strips. Through its effect on PGE2 synthesis, HIV+ IgA could have a dual action. On the one hand, it could enhance immunosuppression at a local level, favouring pathogen growth and subsequent intestinal dysfunction. On the other hand, PGE2 could directly increase intestinal motility and electrolyte/fluid loss. Both effects could be involved in intestinal damage in AIDS.

Animals↗
PubMed1996

Effects of IL-2 on the myocardium. Participation of the sympathetic system.

IL-2 is known to have various effects outside the frame of the immune system and it could have a role as an autocrine modulatory agent in certain cardiac dysfunctions associated to inflammatory cell infiltration of the heart. In this study, by means of binding assays on cardiac membranes or by evaluating contractility and cAMP levels of isolated rat atria in the presence of IL-2, we demonstrate that IL-2 may indirectly stimulate beta-adrenergic-mediated function by triggering the presynaptic release of norepinephrine (NE) on isolated rat atria. Thus it reacts with cardiac tissue inducing a positive inotropic response that can be blocked by the beta-adrenergic antagonist propranolol but not by phentolamine. Binding of the beta-adrenergic antagonist CGP 12177 is not affected by IL-2. Furthermore, chemical sympathectomy with 6-hydroxydopamine (6-OHDA) prevents the inotropic effect of IL-2, while cocaine treatment sensitizes atria to IL-2, indicating that NE secretion is required, and that the beta-adrenergic effect of IL-2 is presynaptic. In addition, IL-2 mimics beta-adrenergic stimulation increasing cAMP synthesis. Colchicine inhibited cAMP stimulation as well as positive inotropism, and both effects of IL-2 were additive with isoproterenol. However, cAMP synthesis could only be partially blocked by propranolol, suggesting that IL-2 stimulated cAMP synthesis both by a direct, beta-adrenergic independent mechanism and by a beta-adrenergic dependent pathway. We conclude that IL-2 induces a positive inotropic response in isolated rat atria through two different pathways: an indirect activation of myocardial beta-adrenergic receptors by releasing catecholamines and a direct action by increasing the production of the second messenger cAMP.

Animals↗
PubMed1996

Induction of ileum muscarinic cholinoceptor signal transduction pathways by rat interferon-gamma.

We have recently shown that rat interferon-gamma (IFN gamma) can trigger a cholinergic muscarinic response upon interaction with isolated rat atria, decreasing both the contractile tension and cAMP synthesis, and increasing cGMP production. Because the intestine is rich in cholinergic muscarinic receptors, and IFN gamma-producing cells are normal components of the mucosal immune system, we investigated whether IFN gamma could also modulate the muscarinic cholinergic activity of the intestine. Our results indicate that IFN gamma may interact with ileum cholinergic muscarinic receptors by inhibiting binding of the radiolabelled antagonist quinuclidinyl benzylate (3H-QNB), decreasing cAMP formation and increasing cGMP synthesis. These effects are associated with increased mechanical activity of the isolated ileum strips, and can be blunted by pretreatment of the tissue with atropine.

Animals↗
PubMed1995

Opposite effects of interleukin-2 (IL-2) and interferon gamma (IFN gamma) on rat atria contractility.

We have recently shown that interleukin 2 (IL-2) can increase the contractile strength or rat atrial muscle through the activation of phospholipases and protein kinase C. The results of this study confirm that the reaction of IL-2 with rat atria involves protein kinase C and not the Ca(++)-calmodulin dependent kinases. Phorbol 12-myristate 13-acetate (PMA), a tumor promoter that activates protein kinase C directly (bypassing the phosphoinositide turnover step), has effects that are similar to those of IL-2 on atrial contractility. Furthermore, preincubation of the tissue with PMA prevents the IL-2 effect, suggesting that the kinases activated by the tumor promoter and IL-2 share a common substrate. This effect of IL-2 on atrial contractility opposes the cholinomimetic inhibitory action of IFN gamma. Thus, preincubation of cardiac tissue with IL-2 or PMA eliminates the effects of IFN gamma and viceversa. Apparently, the inhibitory action of IL-2 on IFN gamma involves an impaired response or atria to cholinergic activation, as IL-2 shifts to the right the dose response curve of the tissue to the cholinergic muscarinic agonist carbachol. Protein kinase C is also necessary for the occurrence of the IL-2-IFN gamma interference. The results of this study suggest that, during an inflammatory reaction in the heart, the balance of the two lymphokines can determine changes in the response of the tissue to autonomous nervous system agonists or to the cytokines that mimic the effects of these neurotransmitters.

Animals↗
PubMed1993

Inhibition of normal natural killer cytotoxicity by sera from hemophilic patients.

In this study we searched for circulating antibodies or other serum factors that could account for the natural killer (NK) defect observed in hemophiliacs (He) infected with the human immunodeficiency virus (HIV). We analyzed the effect of negative or positive sera for HIV from He on normal NK activity. We showed that sera from He interfered with normal NK cytotoxicity. The inhibitory activity was higher in HIV+ sera and increased as the HIV disease progressed. HIV- sera also inhibited NK function, although to a lesser extent than HIV+, and it was probably due to isoimmunization through replacement treatment with plasma-derived concentrates. For each individual, no direct correlation was found between NK inhibition (NK-INH) of sera and the NK activity of He peripheral blood mononuclear cells (PBMC). Furthermore, He serum was poorly inhibitory on autologous PBMC. Preincubation of allogenic effector or target cells with He sera revealed that the inhibitory effect was the result of the reaction with these cells. A positive correlation was found by comparing NK-INH of whole He sera with the serum levels of circulating immune complexes. When the NK-INH assay was performed using the same concentration of DEAE-purified IgG from N, HIV- or HIV+, we found that HIV+ AIDS IgG was more inhibitory than the others.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Autoantibodies in HIV-infected patients that modulate the cholinergic activity of heart and gut tissue.

In human immune deficiency virus (HIV) disease, direct infection of heart tissue with HIV and repeated intestinal infections with opportunistic pathogens are thought to be the main cause of cardiac disease and diarrhoea respectively. A role for autoimmune phenomena may also be involved in the pathogeny of HIV disease. In this study, we demonstrate that immunoglobulins from the A and G classes from HIV positive patients are able to interfere with the function of the muscarinic cholinergic receptors from heart and gut. Both IgA and IgG HIV+ preparations decreased the tension of isolated atria and increased the tension of isolated ileum. The mechanical effect of carbachol was inhibited in both atria and ileum preparations, when they were preincubated with either IgA or IgG HIV+ fractions. An inhibitor of muscarinic cholinergic receptors (atropine) impaired the negative inotropic action of HIV+ immunoglobulins (Ig) on the heart and prevented the positive inotropic effect of HIV+ Igs on ileum. HIV+ IgA fraction was approximately ten fold more potent to interfere with the cholinergic function as compared to the IgG fraction. These results suggest that antibodies present in HIV+ serum may also modulate muscle's cholinergic activity in the heart and ileum from HIV+patients.

Animals↗
PubMed1992

Anti-leukocyte antibodies as a consequence of HIV infection in HIV+ individuals.

Antibodies (Ab) that induce antibody-dependent cell-mediated cytotoxicity (ADCC) against non-T lymphocytes, anti-HLA class II specific Ab and anti-PMN were tested in hemophilic (He) patients who were alloimmunized because they had received replacement treatment with blood derivates and become infected with HIV, as well as in those who remained seronegative. In addition, the serum reactivity of spouses of HIV+ individuals and their children was studied to determine the effect of HIV infection in the absence of concomitant alloimmunization. The results of this study indicate that ADCC Ab were already present in HIV- He, suggesting the influence of alloimmunization. Their titer increased after appearance of HIV disease. While low reactivity against class II antigens was observed in HIV- He, activity augmented sharply after HIV infection and increased further with disease progression. Anti-PMN reactivity followed a similar pattern. Anti-class II, ADCC Ab and anti-PMN were also detected in the asymptomatic HIV+ spouses of HIV+ patients in titers that were similar to those of asymptomatic HIV+ He. In children born to HIV+ mothers in whom HIV infection was confirmed, anti-class II, ADCC Ab and anti-PMN reactivity were also observed, and activity increased after the onset of disease. These results suggest that induction of anti-leukocyte Ab occurs in the absence of massive allostimulation after HIV infection. HIV infection may enhance preexisting class II and anti-leukocyte response in allostimulated individuals.

Adult↗
PubMed1992

[HIV-1 infection in patients with hemophilia. The Argentinian experience from 1983 to 1990].

We present studies on the evolution of HIV-1 infection in 638 hemophilic patients receiving commercial antihemophilic concentrates (CAH) at the Institute of Hematological Research and the Argentine Foundation of Hemophilia between 1983 and 1990. Positive serology for HIV-1 was detected in 30% of the patients studied. Prevalence of HIV-1 infection was higher (about 70%) in the group with severe hemophilia requiring more CAH, but there were no differences between patients with hemophilia A or B. Sexual transmission was demonstrated in 8/64 women (13%) with stable sexual relationship with HIV-1 + hemophilic patients. Three of them became pregnant, and HIV-1 infection was demonstrated in two of the three children. In general, the clinical evolution, as well as the hematologic and immunologic parameters of infected patients were similar to those described for the hemophilic population in other occidental countries. Opportunistic infections were also those observed elsewhere (with predominance of P. carinii pneumonia and disseminated Candida infections). However, the presence of fatal chagasic encephalitis in two of the patients with AIDS is unusual. Thus, central nervous system localization of T. cruzi (which can be observed during the acute period of T. cruzi infection or in immunosuppressed patients), must be considered as a possible severe complication of HIV-1 disease in T. cruzi infected patients.

AIDS-Related Opportunistic Infections↗
PubMed1991

Active alpha 2 and beta adrenoceptors in lymphocytes from patients with chronic lymphocytic leukemia.

A single population of alpha 2 adrenoceptors was characterized in intact B lymphocytes from patients with chronic lymphocytic leukemia (B-CLL) by binding and saturation studies with 3H labelled yohimbine and by competition studies with alpha adrenergic antagonists. While the affinity of B-CLL alpha 2 adrenoceptors was low (KD: 9.81 nM-20.98 nM), each cell expressed a large number of receptors. No binding of the alpha 1 adrenoceptor antagonist prazosin was observed and the binding properties of beta adrenergic receptors (assayed with 3H-labelled dihydroalprenolol), were similar to those described for normal lymphocytes. Reaction of B-CLL with the beta adrenergic agonist isoproterenol raised the levels of cAMP in 11/13 patients tested, and in 8 of these, incubation with the alpha 2 adrenergic agonist clonidine prevented the effect and reduced the basal cAMP levels. The presence of active alpha 2 adrenoceptors on B-CLL lymphocytes may be involved in the regulation of metabolic pathways that affect cell functions and favor neoplastic growth.

Aged↗