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Biomedical subjects

M Campos

Publications and source records attributed to M Campos.

At least 181 records · Page 10Linked to original sources
PubMed1986

The heterogeneity of type IIA von Willebrand's disease: studies with protease inhibitors.

The absence of large von Willebrand factor (vWF) multimers from plasma is a characteristic of Type IIA von Willebrand's disease (vWD) and is thought to contribute to the clinical expression of this disorder. Recently, three IIA patients have been reported in whom intermediate and large multimers could be restored if blood were collected in 5 mm EDTA, 6 mmol/L N-ethylmaleimide, and 1 mmol/L leupeptin. This suggested that absence of large multimers resulted from in vitro proteolysis. We have now collected blood from ten Type IIA vWD patients in these inhibitors but were not able to detect large multimers in the plasma of any of them. In addition, intermediate-sized multimers were reduced or completely absent in all. The inclusion of inhibitors in the citrate anticoagulant, as compared to citrate alone, was found to increase the relative proportion of intermediate multimers in some patients but had no effect in others, and in none did it restore large multimers to plasma. The results with platelet vWF were more varied. Four patients showed an absence or decrease of large multimers, whereas in seven patients large multimers were present. When compared with citrate anticoagulant alone, the inclusion of inhibitors in the anticoagulant had little or no effect on the platelet multimeric pattern. 1-Deamino-8-D-Arginine Vasopressin (DDAVP) was administered to six patients from five families. Two patients from one family showed complete correction and a third patient showed almost complete correction of her bleeding time. Two patients showed minimal correction and one showed no detectable correction. An increase in multimer size after DDAVP tended to be associated with correction of the bleeding time. However, in no case did the largest multimers appear in plasma even in patients with complete bleeding time correction. The presence or absence of inhibitors in the anticoagulant had little or no effect on the multimeric pattern after DDAVP. These results indicate that Type IIA vWD is a heterogeneous disorder in which absence of largest and intermediate multimers is an in vivo phenomenon.

Bleeding Time↗
PubMed1985

Inability to detect a K cell in bovine peripheral blood leukocytes.

Antibody-dependent cellular cytotoxicity to viral-infected cells, chicken red blood cells, and tumor cells was tested using different effector cell populations: polymorphonuclear cells, mononuclear cells, and mononuclear cells separated into adherent and nonadherent populations by Sephadex G-10. Polymorphonuclear cells were the most efficient mediators of antibody-dependent cellular cytotoxicity against most targets, although a combination of G-10 adherent and polymorphonuclear cells was more efficient in killing infectious bovine rhinotracheitis virus-infected cells than either single cell population. Removal of G-10 adherent cells from the mononuclear cell population removed all antibody-dependent cellular cytotoxicity from that population, indicating the lack of a typical K cell in bovine peripheral blood.

Animals↗
PubMed1985

Cell-mediated cytotoxicity of bovine mononuclear cells to IBRV-infected cells: dependence on Sephadex G-10 adherent cells.

Following intranasal inoculation of cattle with infectious bovine rhinotracheitis virus (IBRV) mononuclear cells that produced a genetically unrestricted cytotoxic response against IBRV-infected, but not against uninfected cells, were present in peripheral blood. Cytotoxicity was detected between 6 and 14 days after primary infection in a 20 h, but not in a 5 h, 51Cr-release assay. Cytotoxic activity was present in peripheral blood mononuclear cells from infected and subsequently hyperimmunized cattle for a considerably longer time. Neither natural cytotoxicity, antibody-dependent cell cytotoxicity, nor antibody produced during the assay was responsible for the cytotoxicity. However, cytotoxicity was dependent upon an adherent mononuclear cell that was partially removed by passage over nylon wool and completely removed by passage over Sephadex G-10.

Animals↗
PubMed1985

Physicochemical properties of a beta-lactamase from Streptomyces UCSM-104.

A purified beta-lactamase from Streptomyces UCSM-104 shows the presence of three subforms when stained for protein and/or for activity after polyacrylamide gel electrophoresis or after electrofocusing. The pI values of the three subforms were 5.45, 5.30 and 5.10, respectively. The respective electrophoretic mobilities were 4.6 X 10(-5), 5.2 X 10(-5) and 5.9 X 10(-5)m2/sV. Relative molecular mass of 14,900 was determined. The amino acid composition was established. Cysteine was not detected. A fairly high proline content (8.3%) differentiates this enzyme from other beta-lactamases. Lysine was the only N-terminal amino acid detected after dansylation. The possible origin of the subforms is discussed.

Amino Acids↗
PubMed1985

Isolation of bovine eosinophils by density gradient centrifugation.

A method for the isolation of an enriched population (greater than 60%) of bovine eosinophils was developed, using density gradient centrifugation. Eosinophils were isolated from peripheral blood by centrifugation on a density gradient medium of sp gr 1.092. Viability was greater than or equal to 95%, and the isolated eosinophils were found to be functional in chemokinetic and antibody-dependent cellular-cytotoxicity assays. This method represents a simple, rapid method for obtaining bovine eosinophils that can be used in a variety of assays of eosinophil function.

Animals↗
PubMed1984

Potassium-p-nitrophenyl phosphate interactions with (Na+ + K+)-ATPase. Their relevance to phosphatase activity.

The K+-dependent p-nitrophenylphosphatase activity catalyzed by purified (Na+ + K+)-ATPase from pig kidney shows substrate inhibition (Ki about 9.5 mM at 2.1 mM Mg2+). Potassium antagonizes and sodium favours this inhibition. In addition , K+ reduces the apparent affinity for substrate activation, whereas p-nitrophenyl phosphate reduces the apparent affinity for K+ activation. In the absence of Mg2+, p-nitrophenyl phosphate, as well as ATP, accelerates the release of Rb+ from the Rb+ occluded unphosphorylated enzyme. With no Mg2+ and with 0.5 mM KCl, trypsin inactivation of (Na+ + K+)-ATPase as a function of time follows a single exponential but is transformed into a double exponential when 1 mM ATP or 5 mM p-nitrophenyl phosphate are also present. In the presence of 3 mM MgCl2, 5 mM p-nitrophenyl phosphate and without KCl the trypsin inactivation pattern is that described for the E1 enzyme form; the addition of 10 mM KCl changes the pattern which, after about 6 min delay, follows a single exponential. These results suggest that (i) the shifting of the enzyme toward the E1 state is the basis for substrate inhibition of the p-nitrophenylphosphatase activity of(Na+ + K+)-ATPase, and (ii) the substrate site during phosphatase activity is distinct from the low-affinity ATP site.

Animals↗
PubMed1983

Role of progesterone on oocyte maturation in the egg-brooding hylid frog Gastrotheca riobambae (Fowler).

In the egg-brooding frog Gastrotheca riobambae (Fowler), oocyte maturation is comparable to the situation of other frog species. In isolated follicles, progesterone induces only germinal vesicle breakdown (GVBD), while human chorionic gonadotropin (hCG) induces GVBD and ovulation. In addition, defolliculated oocytes respond with GVBD to the treatment with progesterone, while hCG has no effect. As in other frogs, oocyte maturation in vitro depends on hormonal action and on the presence of divalent cations. In this frog, progesterone or a similar hormone conditions the brooding pouch for reproduction and induces pouch closure. Follicles from frogs with closed pouches showed GVBD after 15-17 hours of incubation with progesterone, while those from frogs with open pouches took 19-24 hours for GVBD. These findings suggest that follicles become stimulated for maturation when the pouch is closed and that this stimulated condition is maintained for several weeks in advance of the process of oocyte maturation. In G. riobambae, the external appearance of the pouch aperture indicates the reproductive condition of the ovary.

Animals↗
PubMed1982

Natural cell-mediated cytotoxicity of bovine mononuclear cells against virus-infected cells.

The ability of mononuclear cells (MC) from peripheral blood of normal cattle to lyse a variety of cells was tested in a 51Cr-release microcytotoxicity assay. Several types of bovine cells infected with parainfluenza 3 virus (PI3V) were susceptible to natural cytotoxicity. Bovine cells infected with infectious bovine rhinotracheitis virus or noncytopathogenic bovine viral diarrhea virus, uninfected bovine cells, and human cell lines MOLT-3, HSB-2, K562, and U-937 were not susceptible. The period of time that target cells need to be infected with PI3V to achieve maximal cytotoxicity was determined. Target cells were infected with PI3V and MC, added 1 h later. After the addition of effector cells, significant levels of cytotoxicity were recorded at 17 h. Maximal cytotoxicity occurred 22 to 24 h postinfection. To define the optimal time that MC must be present, cells were infected with PI3V for a total of 24 h, and MC were left in contact with target cells for various time intervals. Maximal cytotoxicity was recorded when effector cells were present for 20 h, suggesting that a period of activation was needed to stimulate effector cell function. Removal of adherent mononuclear cells on Sephadex G-10 columns did not reduce the low level of cytotoxicity against uninfected target cells, but markedly reduced the level of cytotoxicity against PI3V-infected cells. The effector cell was nonphagocytic and nonadherent. These characteristics and the fact that target cell lysis was independent of genetic restriction indicate that effector cells are similar to natural killer cells described in other species.

Animals↗
PubMed1981

A (Ca2+, Mg2+)-ATPase activity in plasma membrane fragments isolated from squid nerves.

A (Ca2+, Mg2+)-ATPase activity and a (Ca2+, Mg2+)-dependent phosphorylation from ATP have been found in plasma membrane fragments from squid optical nerves under conditions where contamination by intracellular organelles is unlikely. The properties of this (Ca2+, Mg2+)-ATPase activity are almost identical to those of the ATP-dependent uncoupled Ca2+ efflux observed in dialyzed squid giant axons. This gives further support to the notion that the mechanism responsible for maintaining the low levels of ionized Ca concentration in nerves at rest is not a Na+-Ca2+ exchange system but an ATP-driven uncoupled Ca2+ pump.

Adenosine Triphosphatases↗
PubMedDate not supplied

Appendiceal stump abscess.

Recurrence of traditionally treated appendicitis is rarely reported but known to surgeons and is probably underestimated. We described a case, illustrated by CT, of stump abscess 2 years after laparoscopic appendectomy. Sonography and CT are helpful in detecting pericecal changes, but diagnosis is confirmed by laparotomy.

Abdominal Abscess↗
PubMedDate not supplied

Sclerosing cholangitis associated to cryptosporidiosis in liver-transplanted children.

UNLABELLED: Three children of a series of 461 pediatric liver transplant recipients developed diffuse cholangitis associated with intestinal cryptosporidium carriage. All three received immunosuppression consisting of tacrolimus and prednisone. Cryprosporidium carriage was treated with paramomycin, while immunosuppression was decreased according to graft tolerance. No other infectious pathogens were found, and no vascular problems were detected. Bile duct anastomosis was reoperated in all three, but biliary cirrhosis developed in one patient, requiring retransplantation. All three patients are alive and well, and free of intestinal parasites on follow-up. CONCLUSION: Cryptosporidium intestinal infection may play a role in some cases of otherwise unexplained cholangiopathies in pediatric liver transplant recipients. This may lead to significant morbidity, including need for retransplantation.

Child↗