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Biomedical subjects

G Ortega

Publications and source records attributed to G Ortega.

At least 91 records · Page 5Linked to original sources
PubMed1989

Actions of cyclosporin A on cultured rat mesangial cells.

The effects of cyclosporin A (CsA) on planar surface area of cultured rat mesangial cells (PCSA) and cross-sectional area of isolated rat glomeruli (GCSA) were tested. The same experiments were performed after preincubation with platelet activating factor (PAF) antagonists (BN 52021, alprazolam) or calcium channel blockers (verapamil). Areas of cells or glomeruli were analyzed by a computer-assisted method. CsA reduced PCSA in a time-dependent (significant effects began at 15 min, about 12% of reduction with 10(-6) M CsA) and dose-dependent (no effect at 10(-9) M CsA, maximal reduction of about 30% at 60 min of incubation with 10(-7) M CsA) fashion. BN 52021 (5.10(-5) M) and alprazolam (10(-5) M) completely inhibited the reduction of mesangial cell area induced by CsA. Verapamil (10(-5) M) only partially inhibited this action. Glomerular cross-sectional area decreased after 30 minutes of incubation with 10(-6) M CsA (1.45 +/- 0.02 vs. 1.55 +/- 0.02 m2.10(-8), P less than 0.001), an effect that was inhibited by BN 52021 or verapamil. In addition, 10(-6) M CsA increased PAF production by isolated rat glomeruli (425 +/- 80 pg/mg vs. 198 +/- 13 pg/mg in control glomeruli, P less than 0.01), an effect which was not inhibited by verapamil. These results suggest that CsA could reduce GFR by decreasing the glomerular ultrafiltration coefficient, perhaps as a consequence of the contraction of mesangial cells. PAF seems to play a pivotal role in the genesis of this action.

Animals↗
PubMed1989

Interaction of bilirubin with gangliosides.

Gangliosides seem to play an important role in the interaction of the neurotoxic pigment bilirubin with the synaptosomal plasma membrane (Vázquez et al. [1988] J. Biol. Chem. 263, 1255-1265). In this report, a further characterization of the bilirubin-ganglioside interaction is presented. The interaction is fast, and it is observed at any pH in the range 7.0-9.0. The characteristics of the interaction are different from those observed with other membrane lipids, including sphingomyelin. A model of binding to a single population of sites is able to adequately fit the experimental data. This model predicts a decrease in the tendency of bilirubin to interact with gangliosides and an increase in the binding capacity as the pH is decreased from 8.0 to 7.0. Our data would suggest a role for gangliosides in explaining the preferential accumulation of bilirubin in some areas of the brain and the toxic effect of this pigment in neuronal membrane-related functions.

Animals↗
PubMed1989

[Corynebacterium D2-induced encrusted cystitis].

Two cases of patients with cystitis cystica secondary to urine infection, caused by resistant corynebacterium D2, are presented. The clinical features were important dysuria and frequency, alkaline urine Ph (Ph 8 and 9). The urine cultures were obtained with the standard techniques, after 72 hours of incubation. They were treated with vancomycin, ciprofloxacin and hydroxinamic acid with good response.

Aged↗
PubMed1989

[Ascites and pleural effusion. Study and follow-up of 79 patients].

We reviewed 79 patients with a picture of pleural effusion (EP) and ascites, who represented 8% of a total of 982 pleural effusions studied. Liver cirrhosis (CH), 37 cases (47%), disseminated carcinomatosis, 31 cases (39.5%), and congestive heart failure, 6 cases (7%), were the main causes. We made two groups of liver cirrhosis: A) liver cirrhosis with hydropic decompensation, 12 patients (15%), and B) liver cirrhosis with an additional complication added to the above, 25 patients (31.5%), this being infectious in 88% of the cases. In the B group there were cases of left hydrothorax, more features of effusion and a lower survival at 3 months of follow-up than in tha A group. Effusions of neoplastic origin were most frequently seen in tumors of the ovary, digestive system, lymphomas and undetermined origin. In malignant effusions, the cytology was positive in pleura in 60% and in ascites in 55%. Twenty percent of peritoneal fluids and 47% of pleural effusions were serohemorrhagic and 100% and 88%, respectively, were of exudative nature. In liver cirrhosis the ascites was serofibrinous and transudated (100% in group A and 85.5% in B) and the pleural effusion was a serofibrinous transudate except in the cases in which there was an added infection. We confirm the ominous prognosis of the coexistence of pleural effusion and ascites.

Adult↗
PubMed1988

A cost comparison analysis for screening and vaccination of hospital personnel with high- and low-prevalence hepatitis B virus antibodies in California.

We compared the cost of antibody screening and the projected cost for hepatitis B vaccination of antibody-negative individuals at hospitals with "high prevalence" and "low prevalence" rates for hepatitis B virus antibodies among their employees. The use of hepatitis B core antibody for screening and subsequent hepatitis B vaccination of antibody-negative personnel was most cost-effective for hospitals considered to have high prevalence for hepatitis B virus antibodies among its staff, although use of hepatitis B surface antibody in this setting only increased costs by 1.4%. In a hospital with low prevalence for hepatitis B virus antibodies among its staff, use of hepatitis B surface antibody and subsequent vaccination of antibody-negative individuals was the most cost-effective approach, while use of hepatitis B core antibody for the above purposes would have increased costs by 3.4%. The use of both hepatitis B surface antibody and core antibody in either setting followed by immunization was least economical, as costs were increased by 13% and 13.5% respectively. We concluded that hepatitis B core antibody should be used for screening in hospitals with high prevalence for hepatitis B virus antibodies among employees while hepatitis B surface antibody be used for screening in hospitals with low prevalence for hepatitis B virus antibodies among employees. A prediction of high and low prevalence for hepatitis B virus antibodies in hospital personnel may be made by knowledge of the distribution in ethnicity of staff.

Adolescent↗
PubMed1986

Role of Ly-6 in lymphocyte activation. I. Characterization of a monoclonal antibody to a nonpolymorphic Ly-6 specificity.

In studies with alloantisera and monoclonal antibodies (mAb) a number of antigenic determinants have been defined that are the products of the Ly-6 locus on murine chromosome 2 and that are expressed primarily on B and T lymphoid cells. It remains controversial whether these antigenic determinants are encoded by a single gene or a multigene complex. We have characterized a new rat mAb, D7, which recognizes a cell surface antigen whose expression on nonactivated peripheral lymphocytes varies from strain to strain. The phenotype of the staining profile, i.e., high or low percentage of D7-positive cells, mapped to the Ly-6 locus as assayed by strain distribution studies, RI lines, and Ly-6 congenic strains. The binding of D7 to Ly-6.1-positive strains could be inhibited by mAb directed to the Ly-6E.1 specificity, whereas D7 could inhibit the binding of mAb specific for Ly-6A.2 to cells from Ly-6.2-positive strains. Coprecipitation studies followed by Western blot analysis confirmed that D7 reacts with both Ly-6E.1- and Ly-6A.2-bearing molecules. The most likely explanation for these findings is that Ly-6A.2 and Ly-6E.1 represent allelic specificities. Further dissection of the complexity of the Ly-6 antigen system and determination of its possible functional importance in lymphocyte activation should be greatly facilitated by the availability of xenogeneic mAb that recognize framework determinants on multiple Ly-6 products.

Alleles↗
PubMed1986

Role of Ly-6 in lymphocyte activation. II. Induction of T cell activation by monoclonal anti-Ly-6 antibodies.

The Ly-6 locus controls the expression and/or encodes for alloantigenic specificities found primarily on subpopulations of murine T and B lymphocytes. We have recently identified and characterized a new rat mAb, D7, that recognizes a nonpolymorphic Ly-6 specificity. After crosslinking by anti-Ig reagents or by Fc receptor-bearing accessory cells, mAb D7 could induce IL-2 production from T cell hybridomas, and in the presence of PMA could trigger a vigorous proliferative response in resting peripheral T cells. The addition of mAb D7 to cultures of antigen- and alloantigen-, but not mitogen-stimulated T cells resulted in a marked augmentation of the proliferative response. A number of other well-characterized mAbs to Ly-6 locus products could also stimulate a T cell proliferative response after crosslinking by anti-Ig and in the presence of PMA. These results strongly suggest that Ly-6 molecules may play a critical role in the T cell activation cascade, either as receptors for an unidentified soluble or cell-associated ligand or as transducing molecules that modulate signals initiated by antigen stimulation of the T3-Ti complex.

Animals↗
PubMed1986

Analysis of transverse maxillary diameter. Using Mayoral's method, in Cuban and Namibian young people with normal occlusion.

The transverse maxillary diameter has been studied for several decades. Mayoral made a study to find the maxillary width by means of the intermolar and interbicuspid distances. We made a study of 540 14-, 15- and 16-year-old Europoid Cubans, Negroid Cubans, and Namibians. They were subdivided by sex and age, forming groups of 30 for each age, sex and ethnic group. The boys almost always had higher figures than the girls, and the Negroid groups always had higher figures than the Europoid Cubans. In almost no cases were significant differences found between the Negroid Cubans and the Namibians.

Adolescent↗