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Biomedical subjects

M Campos

Publications and source records attributed to M Campos.

At least 163 records · Page 9Linked to original sources
PubMed1989

2'-5' oligo-A-synthetase activity in bovine peripheral blood leukocytes and alveolar macrophages exposed to recombinant interferons and tumor necrosis factor-alpha.

In vitro treatment of bovine peripheral blood mononuclear leukocytes, polymorphonuclear neutrophilic granulocytes and alveolar macrophages with recombinant bovine interferons -alpha 1 1, -beta 2 or -gamma induced an immediate increase in the intracellular level of 2'-5' oligoadenylate synthetase activity. The induction was dose-dependent, with interferon -alpha 1 1 and -beta 2 being more potent than interferon-gamma. Maximal levels were reached within 10-12 h with IFN-alpha 1 1, which corresponded well with findings in vivo. In contrast to what has been found in nonlymphoid bovine cells, tumour necrosis factor-alpha did not potentiate the induction of 2-5A synthetase by interferons, neither did it by itself induce the enzyme.

2',5'-Oligoadenylate Synthetase↗
PubMed1988

Binding of manganese ions to the Na+/K+-ATPase during phosphorylation by ATP.

The aim of the present work was to study the Mg2+-Na+/K+-ATPase interaction that was proposed to lead to the formation of a stable Mg-enzyme complex during phosphorylation from ATP. Instead of Mg we used Mn, which can replace Mg as essential activator of Na+/K+-ATPase activity. The amounts of steady-state Mn bound to the enzyme were estimated at 0 degree C on the basis of the 54Mn remaining in the effluent after passing the reaction mixture through a cation exchange resin column. As a function of the MnCl2 concentration, the amount of Mn retained by the enzyme in the absence and presence of ATP showed a saturable and a linear component; the slope of the linear component was the same in both instances (0.016 nmol/mg per microM). The ATP-dependent Mn binding could be adjusted to a hyperbolic function with a Km of 0.76 microM. The ratio [ATP-dependent E-Mn]/[E-P] measured at 5 microM MnCl2 and 5 microM ATP was not different from 1.0, both in native (Mn-E2-P) as well as in a chymotrypsin treated enzyme (Mn-E1-P). When the Mn.E-P complex was allowed to react with KCl (E2-P form) or ADP (E1-P form), the enzyme was dephosphorylated and simultaneously lost the strongly bound Mn in such a way that the ratio [ATP-dependent E-Mn]/[E-P] remained 1:1. These results show the existence of strongly bound Mn ions to Na+/K+-ATPase during phosphorylation by ATP. That binding is (i) of high affinity for Mn, (ii) probably on a single site, and (iii) with a stoichiometry Mn-Pi of 1:1.

Adenosine Triphosphate↗
PubMed1988

Phosphatase activity of Na+/K+-ATPase. Enzyme conformations from ligands interactions and Rb occlusion experiments.

The present work compares the effects of several ligands (phosphatase substrates, MgCl2, RbCl and inorganic phosphate) and temperature on the phosphatase activity and the E2(Rb) occluded conformation of Na+/K+-ATPase. Cooling from 37 degrees C to 20 degrees C and 0 degrees C (hydrolysis experiments) or from 20 degrees C to 0 degrees C (occlusion experiments) had the following consequences: (i) dramatically reduced the Vmax for p-nitrophenyl phosphate and acetyl phosphate hydrolysis but it produced little or no changes in the Km for the substrates; (ii) led to a 5-fold drop in the Km for the inorganic phosphate-induced di-occlusion of E2(Rb); (iii) reduced the K0.5 and curve sigmoidicity of the Rb-stimulated hydrolysis of p-nitrophenyl phosphate and acetyl phosphate and the Rb-promoted E2(Rb) formation. At 20 degrees C, in the presence of 1 mM RbCl and no Mg2+, acetyl phosphate did not affect E2(Rb); with 3 mM MgCl2, acetyl phosphate stimulated a release of Rb from E2(Rb) both in the presence and absence of RbCl in the incubation mixture. As a function of acetyl phosphate concentration the Km for iRb release was indistinguishable from the Km found for stimulation of hydrolysis and enzyme phosphorylation under identical experimental conditions; in addition, the extrapolated di-occluded fraction corresponding to maximal hydrolysis was not different from 100%. These results indicate that although E2(K) might be an intermediary in the phosphatase reaction, the most abundant enzyme conformation during phosphatase turnover is E2 which has no K+ occluded in it. The ligand interactions associated to phosphatase activity do not support an equivalence of this reaction with the dephosphorylation step in the Na+ + K+-dependent ATP hydrolysis; on the other hand, there are similarities with the reversible binding of inorganic phosphate in the presence of Mg2+ and K+ ions.

Animals↗
PubMed1988

Some total and partial reactions of Na+/K+-ATPase using ATP and acetyl phosphate as a substrate.

Acetyl phosphate, as a substrate of (Na+ + K+)-ATPase, was further characterized by comparing its effects with those of ATP on some total and partial reactions carried out by the enzyme. In the absence of Mg2+ acetyl phosphate could not induce disocclusion (release) of Rb+ from E2(Rb); nor did it affect the acceleration of Rb+ release by non-limiting concentrations of ADP. In K+-free solutions and at pH 7.4 sodium ions were essential for ATP hydrolysis by (Na+ + K+)-ATPase; when acetyl phosphate was the substrate a hydrolysis (inhibited by ouabain) was observed in the presence and absence of Na+. In liposomes with (Na+ + K+)-ATPase incorporated and exposed to extravesicular (intracellular) Na+, acetyl phosphate could sustain a ouabain-sensitive Rb+ efflux; the levels of that flux were similar to those obtained with micromolar concentrations of ATP. When the liposomes were incubated in the absence of extravesicular Na+ a ouabain-sensitive Rb+ efflux could not be detected with either substrate. Native (Na+ + K+)-ATPase was phosphorylated at 0 degrees C in the presence of NaCl (50 mM for ATP and 10 mM for acetyl phosphate); after phosphorylation had been stopped by simultaneous addition of excess trans-1,2-diaminocyclohexane-N,N,N',N' tetraacetic acid and 1 M NaCl net synthesis of ATP by addition of ADP was obtained with both phosphoenzymes. The present results show that acetyl phosphate can fuel the overall cycle of cation translocation by (Na+ + K+)-ATPase acting only at the catalytic substrate site; this takes place via the formation of phosphorylated intermediates which can lead to ATP synthesis in a way which is indistinguishable from that obtained with ATP.

Adenosine Triphosphate↗
PubMed1988

Studies on the in vitro biological activities of recombinant bovine tumor necrosis factor (rBoTNF) alpha. I. Synergistic antiviral efficacy of rBoTNF alpha, recombinant bovine interferon gamma (rBoIFN gamma) and their combination.

The recent demonstration of the antiviral activity of recombinant human TNF has launched an interest in the use of TNF alpha for antiviral therapy in veterinary medicine. In the precent report, we demonstrate that pretreatment of bovine cells with rBoTNF alpha reduces the yield of bovine herpesvirus type-1 (BHV-1) from infected cells. Reduction in yield was similar to that observed in the presence of rBoIFN gamma. Similarly, rBoTNF alpha was able to protect bovine cells from virus-induced cytopathology. Enhanced antiviral activity was demonstrated when rBoTNF alpha was administered in combination with rBoIFN gamma. Studies on the induction of 2',5'-oligoadenylate synthetase (2'-5' AS) production by cytokine-treated cells showed that although rBoTNF alpha by itself did not induce 2'-5' AS activity it was capable of enhancing the production of 2'-5' AS by rBoIFN gamma-treated cells. Combination of these two cytokines was also evident in the inhibition of proliferation of treated cells. In contrast, the cytotoxic effect of rBoTNF alpha towards actinomycin D-treated cells was not affected by the combination of rBoTNF alpha with rBoIFN gamma.

2',5'-Oligoadenylate Synthetase↗
PubMed1988

The sensitivity of domestic animal cell lines to eight recombinant human interferons.

The biological activities of eight recombinant human interferons (IFNs) were tested on permanent cell lines and low-passage embryonic cultures from domestic animal tissues. Each titer was compared to its titer on Madin-Darby bovine kidney (MDBK) cells. Although different cells within a species had different sensitivities to different IFNs, the order of sensitivity, in general, was ox, sheep, pig, cat, horse, and dog, the latter being quite insensitive to most IFNs.

Animals↗
PubMed1988

Induction of MHC class II antigens on bovine cells of nonlymphoid origin by recombinant bovine interferon-gamma and tumor necrosis factor-alpha.

To test a hypothesis that immune mechanisms may be involved in the disease process in cattle persistently infected with and immunotolerant to bovine viral diarrhea virus, the effect of interferon-alpha I 1 (IFN-alpha I 1) and -gamma (IFN-gamma) and tumor necrosis factor (TNF-alpha) on bovine endothelial, epithelial, and fibroblast cell class II major histocompatibility complex (MHC) gene product expression was investigated. Untreated control cultures did not express MHC class II antigens. However, following exposure to either recombinant bovine IFN-gamma or TNF-alpha (rBoIFN-gamma, rBoTNF-alpha) MHC class II (Ia) antigen expression was induced on these nonlymphoid cell types. rBoIFN-alpha I 1 did not induce class II antigens, but suppressed their induction by rBoIFN-gamma and TNF-alpha. Induction of Ia-antigen expression, which was dependent on de novo protein synthesis, showed dose- and time-dependency, but once induced, Ia-antigen expression appeared to be fairly stable. Bovine viral diarrhea virus, which, at least in vivo, can induce IFN-alpha, neither induced Ia-antigen expression in the nonlymphoid cell types, nor did the virus interfere with cytokine induction of Ia-antigen expression.

Animals↗
PubMed1988

Cholesteatoma of the middle ear and mastoid. A comparison of CT scan and operative findings.

High-resolution CT scanning accurately depicts the status of the structures of the temporal bone, allowing delineation of pathology prior to surgical exploration of ears with cholesteatoma. It provides information concerning location and extent of disease as well as possible anatomic variations and complications that may be encountered. The main advantages of CT scanning over polytomography are superior soft-tissue contrast resolution and improved spatial detail at a reduced radiation dose for the patient.

Bone Diseases↗
PubMed1988

Head and neck: high field magnetic resonance imaging versus computed tomography.

A comparative review of head and neck lesions examined with both CT and MRI showed that the location and extent of lesions can be more precisely evaluated with MRI. MRI allows better differentiation of neurogenic tumors from other lesions. Vascular structures are easily visualized on MRI without intravenous contrast and can easily be differentiated from lymph nodes. However, cystic lesions and necrotic nodes sometimes could not be differentiated from solid lesions when using MRI.

Branchioma↗
PubMed1988

Temporomandibular joint: role of direct sagittal CT air-contrast arthrogram and MRI.

Direct sagittal CT air-contrast arthrography can provide useful diagnostic information in the evaluation of disorders of the temporomandibular joint. The technique for the performance of this examination is practical and efficient, using a specifically designed head-holder, which is described. This technique effectively complements the clinical and imaging work-up of jaw dysfunction.

Adult↗
PubMed1987

Characterization of Leishmania species from Peru.

Twenty-six isolates of Leishmania parasites of Peruvian origin were studied by isoenzyme electrophoresis of four marker enzymes (ASAT, ALAT, G6PD and GPI), kinetoplast DNA hybridization and monoclonal antibody binding and compared with marker strains of the New World organisms L. b. braziliensis, L. b. guyanensis, L. m. mexicana and L. m. amazonensis. 12 of the isolates studied were of Andean origin; 11 of these were isolated from patients with Andean cutaneous leishmaniasis. The organisms originating from the Peruvian Amazonian forest were isolated from patients with cutaneous (12 cases) or mucocutaneous (2 cases) leishmaniasis. One of the Andean isolates was obtained from an infected phlebotomine vector. 25 of the new isolates were identified as L. braziliensis ssp. according to the three techniques employed. The results of monoclonal antibody binding showed that 23 of the isolates were indistinguishable from L. b. braziliensis. Two isolates identified as L. braziliensis ssp. according to their isoenzyme profiles and k-DNA hybridization patterns could not be classified at the subspecies level. The isolate obtained from the phlebotomine vector could not be identified. No evidence of the existence of parasites of the L. mexicana complex in Peruvian territory was found in this study. The results obtained show a remarkable similarity between Leishmania of Andean origin and L. b. braziliensis.

Alanine Transaminase↗
PubMed1987

Cytotoxic capabilities of bovine lymphocytes after lectin stimulation.

Bovine peripheral blood mononuclear leukocytes (PBML) were stimulated in vitro with the mitogenic lectins concanavalin A (Con A) and phytohemagglutinin. Their cytotoxic capabilities were evaluated in a 51Cr release assay. Lectin-activated bovine effector cells did not mediate antibody dependent cellular cytotoxicity (ADCC) nor direct killing against cultured tumor target cells. Nevertheless, activation of PBML with lectins consistently generated effector cells able to mediate lectin-dependent cellular cytotoxicity. Cultivation of Con A stimulated-PBML for 3 to 4 weeks in the presence of lymphokines-containing IL-2 generated cells with the ability to mediate lysis without using Con A-coated target cells. However, cytotoxic cultures capable of mediating direct lysis of target cells were not able to mediate ADCC.

Animals↗
PubMed1987

CT and MRI of orbital abnormalities in neurofibromatosis and selected craniofacial anomalies.

This article begins with a discussion of normal orbital anatomy and the terminology involved in the description of abnormalities of the orbit. Case reports of patients with neurofibromatosis or with a craniofacial anomaly are presented, and the characteristic orbital findings on both CT and MRI are reviewed. Thus the radiologist's role and the value of CT and MRI in the overall treatment of these often complex abnormalities are elucidated.

Adolescent↗
PubMed1986

A monoclonal antibody that identifies mature T lymphocytes of cattle.

Hybridomas to bovine leukocytes were produced by immunization of BALB/C mice with bovine lymphoblasts and fusion of the mouse spleen cells with mouse myeloma cells. Monoclonal antibodies (MABs) were tested against various cell populations by indirect fluorescent microscopy using fluorochrome conjugated antibodies to mouse immunoglobulins. MAB-15, one of the resulting MABs obtained after cloning antibody-producing hybridomas, reacted with 56.8 +/- 8.4% of peripheral blood mononuclear cells (PBMC). MAB-15 did not react with monocytes or B cells, but did react with T cells (fluorescein isothiocyanate-conjugated peanut agglutinin positive cells). MAB-15 reacted with 3.2% of thymocytes from adult cattle. In addition to reacting with T cells, MAB-15 reacted with neutrophils and eosinophils. MAB-15 was characterized as an IgM antibody that was unable to lyse PBMC in the presence of complement. Thus, MAB-15 is a useful marker of mature T cells in the mononuclear cell population.

Animals↗
PubMed1986

Production of monoclonal antibodies to metacyclic trypomastigotes of Trypanosoma cruzi.

Monoclonal antibodies were produced and characterized to the metacyclic trypomastigotes stage of Trypanosoma cruzi. All the monoclonal antibodies (GR-12C/5; GR-P2B/5; GR-F2B/1; GR-J2C/6; GR-E6B/3; GR-A5B/5) also recognized antigens of epimastigotes of T. cruzi. These antigens are associated with the plasma membrane, flagellum, and an intracellular structure located by the nucleus. Immunoprecipitation using the monoclonal antibodies GR-J2C/6 and GR-E6B/3 followed by SDS-PAGE analysis has led to the following results: GR-J2C/6 precipitated two molecules with apparent molecular weights of 58 and 60 kD; the antigen recognized by GR-E6B/3 was a molecule with molecular weight of 68 kD. Only two of the monoclonal antibodies (GR-12C/5 and GR-P2B/5) recognized antigens of promastigotes of both Leishmania mexicana and L. infantum, and are associated with the plasma membrane.

Antibodies, Monoclonal↗
PubMed1986

In vitro induction of cytotoxic lymphocytes from infectious bovine rhinotracheitis virus hyperimmune cattle.

Cytotoxic lymphocytes against infectious bovine rhinotracheitis virus (IBRV)-infected cells were induced by in vitro stimulation with IBRV antigen of peripheral blood leukocytes obtained from hyperimmune cattle. After one in vitro stimulation with IBRV, cytotoxicity was detected against IBRV-infected autologous target cells, but not against heterologous IBRV-infected or K562 target cells. After 4 in vitro IBRV stimulations at weekly intervals (in the presence of autologous feeder cells followed by interleukin 2 treatment at 2-day intervals), cytotoxicity was detected against autologous-, and to a lesser extent, heterologous-infected cells. Most cells in cytotoxic cultures were positive to a monoclonal antibody shown to react with bovine T lymphocytes.

Animals↗
PubMed1986

Cytotoxicity of bovine lymphocytes after treatment with lymphokines.

Cytotoxic lymphocytes were generated from bovine peripheral blood mononuclear leukocytes after in vitro stimulation with lymphokines that contained interleukin-2. Lymphokine-stimulated cultures were cytotoxic to K562 cells (human natural killer [NK] targets) and YAC-1 cells (mouse NK targets), but not to HSB-2 cells (human NK targets) in a 4-hour, 51Cr-release assay. Cells generated after lymphokine activation also mediated antibody-dependent cellular cytotoxicity to HSB-2 cells. Appearance of effector cells as a function of time in culture, method of stimulation, and cold target competition experiments strongly indicated that direct cytotoxicity and antibody-dependent cellular cytotoxicity may have been mediated by the same cell. Cells generated by similar conditions were able to mediate cytotoxicity against infectious bovine rhinotracheitis virus-infected target cells, especially in an 18-hour assay.

Animals↗