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Biomedical subjects

M Campos

Publications and source records attributed to M Campos.

At least 145 records · Page 8Linked to original sources
PubMed1991

Antibacterial activity of bovine mammary gland lymphocytes following treatment with interleukin-2.

The antibacterial characteristics of bovine mammary gland lymphocytes were evaluated following in vitro activation with recombinant human interleukin-2. Mammary gland effector cell populations were prepared by enzymatic digestion of mammary tissue followed by centrifugation through a discontinuous Percoll gradient. Functional activity of cells cultured for 48 h with or without interleukin-2 were evaluated by direct cytotoxicity using K562 target cells and by antibacterial activity against Staphylococcus aureus. Cytotoxic activity of interleukin-2-treated mammary gland lymphocytes was enhanced compared with control cultures, which exhibited no cytotoxic capabilities following 48 h of culture. Bactericidal activity also was elevated in cells cultured in interleukin-2-supplemented media. Enhanced expression of major histocompatability complex class II molecules on the surface of interleukin-2-treated lymphocytes was associated with the higher level of cell activation. Phenotypic analyses of the recovered population showed that the majority of cells were lymphocytes bearing CD2 molecules. It may be possible to activate these effector cell populations in vivo and increase resistance of the mammary gland to bacterial infections in a nonspecific manner.

Animals↗
PubMed1991

Pathological changes in bovine mammary glands following intramammary infusion of recombinant interleukin-2.

Eighteen lactating dairy cows were used to evaluate the physiological response of mammary glands to increasing doses of recombinant bovine interleukin-2. Right front and rear quarters were intramammarily infused with five different doses (.1 to 100 micrograms per quarter) of interleukin-2 as either a single or multiple treatment. Left front and rear quarters were intramammarily infused with a saline placebo and served as within-animal controls. Milk secretion samples for compositional analysis were collected from each quarter prior to infusion and at 12, 24, 36, and 48 h following infusion. Animals were slaughtered by exsanguination immediately following the 48-h sampling period, and mammary gland tissue was obtained for morphometric analysis. No changes in milk composition were observed between control quarters and those infused with up to 10 micrograms of interleukin-2 per quarter, administered as either a single or multiple treatment. Quarters infused with a single 100-micrograms dose of interleukin-2 or three consecutive doses of 25 and 100 micrograms of interleukin-2 had significantly lower lactose concentrations; there was a concomitant increase in bovine serum albumin, pH, and SCC compared with preinfusion concentrations or with control quarters. Morphometric analysis of tissue demonstrated an increase in stroma, a decrease in lumenal area, and a marked increase in the number of infiltrating leukocytes in those quarters infused with the higher doses of interleukin-2. Results suggest that interleukin-2 can be intrammammarily infused at doses as high as 10 micrograms per quarter without adversely affecting milk quality or normal mammary gland function.

Animals↗
PubMed1991

Application of interferons in the control of infectious diseases of cattle.

Recovery from infection involves a number of complex interactions between specific cells of the immune system. Many of these interactions are mediated by cytokines, which can activate these cells to kill or reduce the replication rate of the pathogen. Availability of large quantities of recombinant cytokines has provided the opportunity to investigate the mechanism or mechanisms of action of each cytokine in vitro and in vivo. In the present review, we describe the application of interferons to reduce morbidity and mortality of cattle suffering from bovine respiratory disease and mastitis. The potential application of interferons in disease modulation as well as the impediments to their use are discussed.

Animals↗
PubMed1991

Immunopotentiation of bovine herpes virus subunit vaccination by interleukin-2.

Cattle were immunized with glycoprotein IV (gIV) from bovine herpes virus-1 (BHV-1). Groups of five animals were then given either 2, 3, 4, or 5 doses of interleukin-2 (IL-2) (0.5 microgram/kg) at 12-hr intervals. Animals that received no IL-2 exhibited specific immune responses that are typical for BHV-1 infection, i.e. enhanced specific cytotoxicity, lymphocyte proliferative responses to gIV, and increased gIV-specific (ELISA) and virus-neutralizing antibodies. Treatment of animals with five doses of IL-2 significantly augmented all of these responses except serum neutralization (P less than 0.05). Furthermore, the dose of IL-2 that was selected did not induce any non-specific responses, i.e. hypergamma-globulinaemia, changes in blood chemistry, increased lymphokine-activated killer (LAK) cell activity, changes in mitogen responsiveness or alterations in the phenotypic profile of circulating lymphocytes. Nor were there any clinical changes associated with IL-2 therapy (e.g. depression, pyrexia, diarrhea). Animals that were treated with less than five doses of IL-2 also exhibited elevated immune responses, but they were not significantly different from untreated immunized controls. Interestingly, animals given five doses of IL-2 responded to minor contaminants present in the gIV preparation. This allows speculation that this dose regimen of IL-2 is not only a potent adjuvant for conventional vaccine immunizing doses, but will also allow the use of minute quantities of antigen for immunization.

Adjuvants, Immunologic↗
PubMed1991

Cytokine activity in bovine mammary gland secretions during the periparturient period.

The presence of cytokine activity in periparturient bovine mammary secretions was evaluated. Mammary secretions were modified for use in biological assays for interleukin-2 (IL-2) like and antiviral activity. The level of IL-2 like activity in mammary gland secretions was lower during the last week of gestation when compared to levels detected approximately two weeks prepartum. Antiviral titers gradually increased as parturition approached. Results from Western blots indicated that the antiviral activity observed in prepartum secretions may be due to tumor necrosis factor (TNF). Interferons (IFN) were not detected in the colostrum samples.

Animals↗
PubMed1991

[Indirect criteria of coronary reperfusion and permeability in patients with acute myocardial infarction who have received thrombolytic therapy].

OBJECTIVE: To evaluate the value of some indirect reperfusion signs (IRS) as markers of coronary artery patency in patients (PTS) with acute myocardial infarction (AMI) submitted to intravenous (IV) thrombolytic therapy (TT). DESIGN: Retrospective study, with analysis of the sensibility (S), specificity (SP) and predictive value (PV) of three IRS: 1. Pain and ST resolution in the first three hours; 2. Peak CK in the first 13 hours; 3. accelerated idioventricular rhythm (AIVR) in the first three hours. SETTING: Coronary Care Unit (CCU) of the Santo António Hospital and Hemodynamic Laboratory of the S. João Hospital, Oporto. PATIENTS: Sixty seven PTS (mean age 53.4 +/- 10.6 years) with confirmed AMI, 62 male and five female, 34 with anterior and 33 with inferior infarction, TT started in the first three hours of the beginning of symptoms in 34 PTS and from three to six hours in 33 PTS, all submitted to coronary angiography in the hospital setting (7.6 +/- 5.9 days after AMI). INTERVENTIONS: IV administration of 1,500,000 U of streptokinase (SK) in 47 PTS and 30 U of APSAC in 20 PTS, preceded by 200 mg IV prednisolone and oral 100 mg acetilsalicylic acid, and followed by IV heparin therapy. Continuous electrocardiographic monitoring, and serial 12 leads ECG and enzymatic assays (at start and 1, 3, 7, 13 and 25 hours of TT). Analysis of the correlation of the three IRS (isolated and in association) with coronary artery patency (TIMI 2 or 3). MEASUREMENTS AND RESULTS: The total patency rate was 79.1%; there was no statistically significant difference with regard to AMI location, time of symptoms onset (0-3 vs 3-6 hours) or thrombolytic agent (SK vs APSAC). The first and second IRS had a high S and a low SP; together S = 79.2%, SP = 64.3% and PV = 89.4%. The third IRS with the first and/or the second one had a low S (about 25%) but SP and PV of 100%. The coronary patency rate of PTS without IRS was always greater than 50%. CONCLUSIONS: The analysed IRS although not very reliable are useful when considered in association. It is possible to assess PTA with high probability of reperfusion if AIVR is present. The absence of IRS does not exclude coronary artery patency. There is still missing more reliable no-invasive reperfusion markers.

Adult↗
PubMed1990

Halothane, isoflurane and enflurane potentiate the effect of noradrenaline on ventricular automaticity in the rat heart: evidence of the involvement of both alpha- and beta-adrenoceptors.

Direct evidence has been sought as to what extent the sensitization of heart to the arrhythmogenic action of sympathomimetic drugs in the presence of the inhalatory anaesthetics, halothane, isoflurane and enflurane, is mediated by either alpha- or beta-adrenoceptors. For this purpose, the effects of isoprenaline, noradrenaline and phenylephrine on ventricular automaticity induced by local injury have been studied in the isolated right ventricle of the rat. Isoprenaline was more potent in increasing ventricular automaticity than either phenylephrine or noradrenaline. The anaesthetic potentiated the effects of noradrenaline, as well as that of higher concentrations of phenylephrine, but not those of isoprenaline. These results support the contention that increases in ventricular automaticity induced by sympathomimetic drugs are mainly mediated by adrenoceptors of the beta-type. However, the simultaneous activation of both alpha- and beta-adrenoceptors seems to be necessary for the effect of the anaesthetics in sensitizing the heart to sympathomimetic drugs.

Anesthetics↗
PubMed1990

Inhibition of antigen-induced and interleukin-2-induced proliferation of bovine peripheral blood leukocytes by inactivated bovine herpes virus 1.

The mechanism by which bovine herpesvirus 1 (BHV-1) predisposes cattle to bacterial pneumonia was investigated by using an in vitro system to demonstrate immunosuppression. At a multiplicity of infection of 0.001, live or inactivated BHV-1 induced a 50% inhibition of the proliferative response of peripheral blood mononuclear leukocytes to antigen (vaccinia virus in vaccinia virus-immunized cattle which were BHV-1 negative) or interleukin-2. At this same multiplicity of infection, the mitogen-induced proliferation of peripheral blood mononuclear leukocytes was unaffected. This inhibition of antigen and interleukin-2-induced proliferative responses could not be reversed by the addition of excess amounts of interleukin-2 and could not be prevented by the addition of indomethacin to block prostaglandin production. Antibodies to BHV-1, especially those specific for glycoproteins gI and gIV, were able to block the inhibitory effect of BHV-1 in these in vitro assays. These results showed that antibody to BHV-1 blocks the immunosuppressive effect of the virus in vitro and suggested that an appropriate antibody response to BHV-1 could protect cattle from virus-induced immunosuppression leading to secondary bacterial pneumonia.

Animals↗
PubMed1990

Expression of tumor necrosis factor-alpha receptors on bovine macrophages, lymphocytes and polymorphonuclear leukocytes, internalization of receptor-bound ligand, and some functional effects.

Tumor necrosis factor-alpha (TNF) is a pluripotent protein produced by cells of the monocyte-macrophage lineage. It has important pro-inflammatory functions and is thought to be involved in the pathogenesis of viral-bacterial lung infections of cattle. Binding and internalization of gold-labeled TNF (TNF-G10) by bovine alveolar macrophages as well as by peripheral blood mononuclear leukocytes (PBML) and polymorphonuclear granulocytes (PMN) have therefore been investigated in conjunction with studies of the effect of TNF on some leukocyte functions. TNF-G10 bound to all leukocyte types to varying extents, which however, did not correlate with the influence of TNF on cell functions. Thus, PMN appeared to possess the lowest number of TNF-receptors, but were nevertheless the most sensitive to functional modulation by TNF. The expression of TNF-receptors appeared to be regulated by other cytokines such as IFN-gamma and IL-2, with IFN-gamma down-regulating receptor expression on all cell types, and IL-2 up-regulating receptor expression on lymphocytes. In macrophages internalization of TNF-G10 occurred via clathrin-coated structures, whereas in lymphocytes and PMN the endosomes appeared to lack distinct coating.

Animals↗
PubMed1990

Inactivation of beta-lactamase from Shigella flexneri UCSF-129 by 6-beta-iodopenicillanic acid: classification of the enzyme.

The beta-lactamase from Shigella flexneri UCSF-129 was irreversible inactivated by 6-beta-iodopenicillanic acid. Only one serine residue was modified, according to the spectra change and the amino acid analyses. A pH variation of 0.3 units was found when the chemically modified enzyme was submitted to isoelectric focusing. The inactivation constant of the fast time course reaction was 0.1 seg-1. Protection of 96% was obtained, using cephradine 2,830 times more concentrated than 6-beta-iodopenicillanic acid. It is suggested that this enzyme belongs to class A, according to Ambler (1980).

Hydrogen-Ion Concentration↗
PubMed1989

Role of interferon-gamma in inducing cytotoxicity of peripheral blood mononuclear leukocytes to bovine herpesvirus type 1 (BHV-1)-infected cells.

In the present study, the possible role of interferon (IFN)-gamma on the induction of cytotoxic activity of peripheral blood mononuclear leukocytes (PBML) from BHV-1-immune cattle was investigated. Supernatants obtained from BHV-1-immune PBML, stimulated under conditions similar to those required to demonstrate cytotoxicity, contained an antiviral substance capable of inducing 2'-5'-oligoadenylate synthetase activity in MDBK cells and MHC class II antigen expression on epithelial cells. These supernatants also contained IFN-alpha, but were devoid of tumor necrosis factor and interleukin-2 biological activities. Further studies during primary infection and hyperimmunization with BHV-1 showed that IFN-gamma production and non-MHC-restricted cytotoxicity against BHV-1-infected targets always occurred concomitantly, suggesting that they represent an important part of the detectable CMI responses mounted against this virus. Furthermore, it was also demonstrated that cytotoxicity of PBML against BHV-1-infected cells was reduced with the addition of antibodies to bovine IFN-gamma to the cytotoxic assay. Bovine recombinant IFN-gamma was able to enhance the in vitro cytotoxic activity of PBML from immune cattle, but not from their nonimmune counterparts. This suggests that other factors, in addition to IFN-gamma, may be essential in the development of non-MHC-restricted cytotoxic responses during BHV-1 infection.

Animals↗
PubMed1989

2',5' oligoadenylate synthetase activity in bovine peripheral blood mononuclear cells following bovine herpesvirus type-1-induced respiratory disease: a prognostic indicator?

Following aerosol-challenge of nonimmune calves with bovine herpesvirus type-1 (BHV-1) the levels of 2',5' oligoadenylate (2-5A) synthetase in peripheral blood mononuclear cells (PBML) increased significantly to peak 4-5 days after BHV-1 infection. This corresponded temporally to the period of highest susceptibility to secondary bacterial infection. Ten days post virus infection, the enzyme levels had returned to baseline values. Aerosol challenge with bacteria (Pasteurella haemolytica) did not induce 2-5A synthetase activity in PBML, neither did it influence the kinetics of 2-5A synthetase induction by virus infection during a dual viral-bacterial infection. Pretreatment of animals with bovine recombinant interferons (IFNs) 0-96 h prior to virus challenge curtailed the viral infection and thus reduced the levels of 2-5A synthetase induced by endogenously produced IFN. A relationship between 2-5A synthetase levels on day 5 post virus infection and clinical outcome of the dual infection was noted. Moreover, the high 2-5A synthetase levels could be correlated with low plasma Zn levels, another indicator of clinical respiratory disease. These results indicate that these two parameters, 2-5A synthetase and plasma Zn, in combination have potential prognostic value in viral-bacterial infections of the respiratory tract.

2',5'-Oligoadenylate Synthetase↗
PubMed1989

Bovine peripheral blood leukocyte population dynamics following treatment with recombinant bovine interferon-alpha I1.

The in vitro functional activity of bovine peripheral blood lymphocytes and the population dynamics of the major peripheral blood leukocyte subpopulations were investigated following the administration of recombinant bovine interferon-alpha I1 (rBoIFN-alpha I1). The intramuscular injection of rBoIFN-alpha I1 induced a 24-h lymphopenia characterized by a decrease in both circulating T and non-T/non-B lymphocytes. An increased CD4/CD8 ratio indicated that there was a relatively greater depletion of the CD8 equivalent subpopulation of T lymphocytes. These changes in lymphocyte trafficking were observed in the absence of a cortisolemia. Coincidental with the lymphopenia, there was a marked decrease in the amplitude of mitogen-induced lymphocyte proliferation responses that probably was caused by a numerical deficit rather than functional deficit in the responder T cells.

Animals↗
PubMed1989

A neutrophil-derived antiviral protein: induction requirements and biological properties.

Polymorphonuclear neutrophilic granulocytes (PMN) have been implicated as playing a role in antiviral defense. In addition to having phagocytic and cytotoxic activities, PMN may produce an antiviral substance with interferon (IFN)-like activity. The product, for which the name polyferon (PF) has been coined, is produced upon direct encounter of PMN with bovine herpesvirus 1 (BHV-1)-infected bovine cells or membranes thereof. Exposure to purified virus only does not induce PF. The intimate interaction between PMN and the membranes was also revealed by electron microscopy studies. Bovine cells infected with herpes simplex virus type 1 could also induce PF production by bovine PMN, whereas cells infected with BHV-2, herpes simplex virus type 2, equine herpesvirus 1, bovine respiratory syncytial virus, bovine viral diarrhea virus, or parainfluenza virus 3 were unable to do so. Results obtained in experiments using transfected cells expressing BHV-1 glycoproteins as well as blocking experiments using BHV-1 glycoprotein-monospecific antibodies suggested that a combination of both viral product(s) and host cell factor(s) unique to bovine cells is required for induction of PF production by PMN. PF, which appeared in detectable amounts 12 to 18 h after exposure of PMN to the appropriate inducer, could not be neutralized by antibodies to bovine IFN-alpha, -beta, and -gamma. PF may nevertheless belong to the IFN family of proteins, as indicated by its ability to induce 2',5'-oligoadenyl synthetase in various cell types that are responsive to bovine IFNs and by its antiviral spectrum. It does, however, differ from the other cytokines in most immunological characteristics tested so far, including major histocompatibility complex class II antigen induction, cell migration, and cytotoxicity.

Animals↗
PubMed1989

Effect of chronic administration of recombinant bovine tumor necrosis factor to cattle.

Cachectin/tumor necrosis factor-alpha (TNF), a protein produced by macrophages upon stimulation, has been implicated as an important mediator of inflammatory processes and of clinical manifestations in chronic infectious diseases. In order to study further the potential role of TNF in infectious diseases, a homologous system was employed in which recombinant Escherichia coli (E. coli) derived bovine TNF (rBoTNF) was injected in cattle, either as a single bolus or in a repetitive treatment-regime. No clinical signs were observed, although changes occurred in hematologic and immunologic parameters when less than 0.5 mg of TNF/100 kg body weight was administered twice daily for 18 days. Prolonged treatment with 0.05-0.5 mg/100 kg induced histologic but no gross changes in the kidneys and liver. When doses were increased above 0.5 mg/100 kg, depression, anorexia, cachexia, and diarrhea appeared rapidly. Pathologic changes were apparent in various tissues including liver, kidneys, and lymphoid organs; body fat depots were depleted. Most of these changes appeared to be reversible; return to normal tissue-morphology occurred within 3 weeks of withdrawal of rBoTNF. The clinical and pathologic changes induced by prolonged rBoTNF administration resembled those observed in some chronic parasitic and viral infections of cattle in which macrophage-activation characteristically occur. Our finding may be relevant to the elucidation of the pathogenesis of these and other chronic infections.

Animals↗
PubMed1989

[The risk factors for hepatitis B virus infection in hospital personnel].

Viral hepatitis is one of the leading causes of disease around the world. In Latin America is a severe public health problem. We conducted a case-control study in the Cayetano Heredia Hospital, Lima, Perú, seeking for risk factors for hepatitis B infection. We found 0.41% of frequency of HBsAg and 8.13% of anti-HBs in the 492 persons screened. Contact with blood was confirmed as a risk factor for hepatitis B infection; disposable needle-wash was also identified as a major risk factor. The personnel of the Sterilization Room is also in high risk for the infection. The nurse-aid personnel was also identified as a high-risk group. We suggest that the needle wash is a risk factor very easy to remove, and also stopping the rotation of the auxiliary personnel could reduce the incidence of the infection in the personnel at risk.

Age Factors↗
PubMed1989

[Risk factors for hepatitis B virus infection among hospital staff].

Viral Hepatitis is one of the leading causes of disease around the world. In Latin America is a severe public health problem. We conducted a case-control study in the Cayetano Heredia Hospital, Lima-Perú, seeking for risk factors for Hepatitis B infection. We found 0.41% of frequency of HBsAg and 8.13% of anti-HBs in the 492 persons screened. Contact with blood was confirmed as a risk factor for Hepatitis B infection; disposable needle-wash was also identified as a major risk factor. The personnel of the Sterilization Room is also in high risk for the infection. The nurse-aid personnel was also identified as a high risk group. We suggest that the needle wash is a risk factor very easy to remove, and also stopping the rotation of the auxiliary personnel could reduce the incidence of the infection in the personnel at risk.

Hepatitis B↗