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Biomedical subjects

J Luis

Publications and source records attributed to J Luis.

47 records · Page 3Linked to original sources
PubMed1979

The effect of peritoneal macrophages from mice injected with Leishmania braziliensis on the in vitro growth of tumor cells.

Leishmania braziliensis reportedly is capable of producing a reduction in the growth of solid and ascites murine leukemia and lymphomas. The possibility that the inhibitory effect on the ascites tumor was produced by the activation of the macrophage peritoneal cell population was explored. It was observed that adherent cells from the peritoneal cavity of L. braziliensis injected mice caused a marked inhibitory effect on the in vitro growth of the 6C3HED lymphoma and EL-4 leukemia cells. This effect was dependent on the degree of the macrophage activation, was not produced by supernatants from cultures of activated macrophages, and it seems that contact cell between target and effector cells is necessary. In addition to being cytostatic, this effect was also cytotoxic. The L. braziliensis activated macrophages were also capable of suppressing the multiplication of normal cells induced by mitogen, but this was not observed if the cells were already undergoing multiplication. A similar cytostatic effect on the tumor cells was observed to be produced by the peritoneal non-adherent cell population of the L. braziliensis injected mice.

Animals↗
PubMed1972

[Not Available].

Explore the source record for details and available documents.

Europe↗
PubMedDate not supplied

Characterization of VIP- and helodermin-preferring receptors on human small cell lung carcinoma cell lines.

We investigated the molecular and pharmacologic characteristics of VIP receptors on two human SCLC cell lines: NCI-N592 and NCI-H345. With NCI-N592 cell, the order of potency of VIP-related peptides in inhibiting 125I-VIP binding and in stimulating cAMP production was typical of the human VIP receptor. By covalent cross-linking, a polypeptide of Mr 62,300 was obtained. Conversely, the behavior of NCI-H345 cell line was totally different: helodermin was the most potent peptide, VIP and PHI were equipotent, while hGRF and secretin were totally ineffective. These results suggest that NCI-N592 cells possess a typical VIP receptor while NCI-H345 cells possess a helodermin-preferring receptor, and that the natural target of helodermin might not be the VIP receptor.

Carcinoma, Small Cell↗
PubMedDate not supplied

Glycosylation of VIP receptors: a molecular basis for receptor heterogeneity.

Apparent molecular weights of VIP-binding proteins differ greatly according to species and to tissue. In this study, we used plasma membranes from various species (human, rat, pig) and tissues (melanoma, intestine, liver), which display major 125I-VIP-labeled components with molecular weights ranging from M(r) = 51,800 to 66,800. With the exception of porcine receptor, the various VIP receptors had similar apparent molecular weights after removal of their N-linked carbohydrates. In addition to differences in the amount of asparagine-linked glycans, our results also revealed differences in the composition of the oligosaccharide chains, which can also account for the heterogeneity in the molecular weights of the VIP receptor.

Animals↗
PubMedDate not supplied

Characterization of the oligosaccharide moiety of VIP receptor from the human pancreatic cell line BxPC-3.

The human pancreatic cell line BxPC-3 displays two classes of binding sites with high and low affinity for VIP. The order of potency of VIP-related peptides in inhibiting either [125I]VIP or [125I]N-AcPACAP27 binding and in stimulating cAMP production was typical of the human VIP receptor. By combining affinity labeling with glycosidase treatments, we have characterized the VIP receptor as a M(r) = 68,200 glycoprotein, consisting of a M(r) = 39,300 polypeptide core with at least three N-linked oligosaccharide chains. In addition, our results revealed the presence of a low amount of sialic acid residues in the carbohydrate moiety of receptor.

Adenocarcinoma↗
PubMedDate not supplied

[Bone mineral density in children with osteogenesis imperfecta].

OBJECT: Osteogenesis imperfecta is the term used for a group of disorders of collagen synthesis which cause increased bone fragility. The aim of our study was to evaluate the BMD in patients with OI. MATERIAL AND METHODS: We used dual-energy x ray absorptiometry, Hologic QDR 4500W (DEXA), to compare the bone mineral density (BMD) of 8 patients aged from 3 years to 20 years who had osteogenesis imperfecta with an age and sex matched control group. RESULTS: DEXA detected highly significant differences in BMD respecting control group. The mean BMD in the patients with osteogenesis imperfecta was 62.6 % of normal in lumbar spine (p < 0.01) and 63.01 % of normal in the femoral neck (p < 0.01) using Wilcoxon test. CONCLUSION: DEXA is an objective, reproductible and sensitive method of measurement of BMD in children. It may help to stablish the diagnosis, to asses prognosis and possibly to monitor the response to different types of treatment.

Absorptiometry, Photon↗
PubMedDate not supplied

Lebecetin, a C-lectin protein from the venom of Macrovipera lebetina that inhibits platelet aggregation and adhesion of cancerous cells.

A novel C-lectin protein, lebecetin, was purified and characterized from the venom of Macrovipera lebetina. It is a disulfide-linked heterodimer of 15 and 16 kD. The subunits are homologous to each other and to the other snake venom proteins of the C-type (Ca(2+)-dependent) lectin superfamily. Lebecetin shows a potent inhibitory effect on whole blood and washed platelets induced by different agonists. It inhibits the agglutination of human fixed platelets in the presence of ristocetin. Lebecetin also interferes with the adhesion of IGR39 melanoma and HT29D4 adenocarcinoma cells. These two lines adhere to lebecetin used as matrix. Lebecetin is also able to strongly reduce IGR39 and HT29D4 cell adhesion to fibrinogen and laminin, but not to fibronectin and collagen types I and IV, respectively. Adhesion properties of lebecetin may thus involve integrin receptors.

Animals↗
PubMedDate not supplied

Serum factors inhibit melanoma cell surface expression of type I and type II IGF receptors.

We have identified one class of IGF-I-binding sites and two classes of IGF-II-binding sites at the surface of the melanoma cell line IGR39. By means of affinity labeling with 125I-IGF-I, 290-300 kDa form was characterized. Using 125I-IGF-II, a 270 kDa polypeptide was labeled, corresponding to the type II IGF receptor. In the two serials of experiments, the order of potency in inhibiting 125I-IGF-I or 125I-IGF-II labeling of IGF-related peptides and alpha IR3, an antibody directed against type I receptor alpha subunit, was the same as in competition experiments. When IGR39 cells were cultured in a serum-free medium, the number of both high affinity IGF-II and IGF-I binding sites was increased, by 8- and 5-fold respectively, without any significant change in Kd values. In both culture conditions, we found IGFBP-2, -3 -4 and a 30 kDa form which Mr was consistent with IGFBP-5 or -6. Except for IGFBP-2, the amount of secreted IGFBPs was modified depending on culture conditions: in conditioned medium from cells cultured with 10% FCS, the amount of IGFBP-3 or -4 was higher, and the amount of the 30 kDa IGFBP was lower when compared to conditioned medium from cells cultured in serum-free medium.

Affinity Labels↗
PubMedDate not supplied

[The biology of the volcano mouse (N. a. alstoni). XXI. Reproductive capacity of wild females in 15 successive matings].

This study comprises an investigation on the reproductive capacity of wild females of the volcano mouse (Neotomodon alstoni alstoni), in 15 successive matings. The neotomodon were captured in the Sierra del Volcán Ajusco (Cerro Pelado, Parres, D.F.). The animals were kept under environmental laboratory conditions, being fed ALBI-LAB pellets and tap water. The matings were performed from may 1985 to August 1988 by pairs and at random, during 12 days. The females were weighed on the day 1 of the mating; the young were sexed on the 7th day of life, and weaned at the 30th day of age. The results were: the mean of the percentages of pregnancy in the 15 matings was 39.6 +/- 3.0, being the highest percentages in Spring-Summer. The size of the litter varied from 1 to 6 young, with a mode of 3 and a global average of 2.7. The means of the percentages of survival at the first week of life and at weaning were 72.9 +/- 3.6 and 70.3 +/- 3.3, respectively. The proportion males-females was 1.2:1. There was not found a significant positive correlation between the weight of the mothers at day 1 of the mating and the size of the litter (r = 0.65, p less than 0.05). These results allow to conclude that in the laboratory the wild volcano mouse exhibits a high reproductive capacity, which demonstrates that this rodent posseses very positive qualities in order to make out of him a new experimental animal.

Animals↗