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R Gamboa

Publications and source records attributed to R Gamboa.

49 records · Page 3Linked to original sources
PubMedDate not supplied

Immunogenetics and clinical aspects of Takayasu's arteritis patients in a Mexican Mestizo population.

OBJECTIVE: The aim of the present work was to study the association between HLA alleles and Takayasu's arteritis in Mexican Mestizo patients. METHODS: The study included 26 Mexican Mestizo patients with Takayasu's arteritis and 99 healthy unrelated individuals. HLA-A, -B and -DR alleles were determined by polymerase chain reaction PCR-SSP RESULTS: Increased gene frequencies were demonstrated for HLA-B15(p=0.009,pC=0.020,OR=3.24,EF=11.9%) and HLA-B52 (p=0.008, pC=0.027, OR=5.16, EF=7.7%), and a decreased frequency for the HLA-A24 allele in patients compared to normal controls (p=0.035, pC=NS, PF=11.1%). When HLA typing was correlated to clinicalfeatures in 24 cases, wefound an increasedfrequencies of HLA-DR14 in patients with systemic arterial hypertension (p=0.005, pC=0.004, OR=24.6, EF=38.3%) and HLA-A2 on patients with pulmonary involvement (p=0.034, pC=0.036, OR=3.67, EF=40.4%) when compared to patients without these clinical manifestations. CONCLUSION: These data confirm HLA-B52 as a relevant susceptibility allele for Takayasu's arteritis and suggest that HLA-B15 could be important as a marker of the disease in Mexican patients. Other class I and/or class II alleles could also be relevant as markers for the clinical features present in these patients.

Adolescent↗
PubMedDate not supplied

[Alleles of the major histocompatibility system associated with susceptibility to the development of Takayasu's arteritis].

OBJECTIVE: Since 1972, the relationship between HLA alleles and the susceptibility for Takayasu arteritis (TA) has been studied on different populations. Hence the results up to date are heterogeneous, the objective of the present review is to analyze the relationship between the presence of HLA alleles and the susceptibility for the development of TA considering the ethnic origin of the studied populations. MATERIAL AND METHODS: We carried out a bibliographic review from clinical articles of case and controls studies on different populations on which the relationship between HLA alleles and the susceptibility for TA was studied, published since 1972 until February 2000. RESULTS: We reviewed articles of studies on Asian, Arab, North-American and Mexican Mestizo populations. On Asian populations TA was associated with HLA-A31, -B52, -B39, -B5 and -DR2, on Arabs with HLA-A2, -A9, -B35 and -DR7, on North-Americans with HLA-DR4 and on Mexican Mestizo with HLA-B5, -B52 and -DR6. On the other hand, recent reports establish that several HLA-B alleles (HLA-B52 and HLA-B39) associated with the disease share some residues important on the antigen presentation. CONCLUSIONS: Hence the heterogeneity of the results obtained up to date, it stands out the increase on HLA-B52 and HLA-DR4 reported on ethnically different populations. More recent data point the possible participation of an epitope located on the peptide-binding site of the HLA-B molecule (positions 63 and 67) that seems to be shared by several alleles associated with the disease. These residues might be participating on the presentation of an unknown antigen that would unchain the disease on the genetically susceptible individuals group.

Alleles↗
PubMedDate not supplied

[Effects of adenosine on automaticity and post-potential oscillations in Purkinje fibers of mammals].

The aim of the present paper was to study the effects of adenosine (ADO) on automaticity and after potential oscillations on canine cardiac Purkinje fibers. ADO concentrations from 10(-8) to 10(-5) M were used. The intracellular electrical activity was recorded with conventional microelectrodes. ADO increased during the first two minutes the basic cycle length (BLC) with concentrations higher than 10(-8) M, to a value 50% above control, later there is a progression to a steady state. The dose-response curve in the steady state is sigmoidal and resembles those of receptor occupation. The slopes of pacemaker potentials have a tendency to decrease along with the increase in BLC length. After potential oscillations decrease with 10(-8) M of ADO but not with larger concentrations. There results supports the hypothesis that ADO produces an increase in the time independent potassium current similar to the one described for atrial and ventricular myocytes. This effect probably depends on specific receptor stimulation. The biphasic time course suggests the existence of subtypes of A1 receptor with different dissociation constants and affinities but with similar actions. The idea that the ADO effects depend mainly on the potassium currents and not on I(f) is supported by the absence of a dose-dependent effects in the oscillatory after potentials.

Adenosine↗
PubMedDate not supplied

[Barium ion blockade on an inward rectifying potassium current in oocytes of the frog Xenopus laevis].

The effect of barium (Ba2+) on inward rectifier K+ current endogenous (IRK-endo) was characterized in Xenopus laevis oocytes with two microelectrodes voltage clamp technique. Varying [K+]o caused a shift in the reversal potential and a change in the straight pert of the slope as expected for K+ current. External Ba2+ blocked IRK-endo displayed lower affinity in the channel in two different forms. The blockade of the peak current was voltage independent, and had a Kd of 0.9 +/- 0.1 mM. In contrast, a second effect on the late current (80 ms). Was both time and voltage dependent, with a Kd that display monoexponential voltage dependence (tau = 50 +/- mV.) These observations suggest the presence of two different binding sites for Ba2+, one in the external vestibule of the channel and another lying within the channel. Our results demonstrate the existence of an endogenous K+ current in Xenopus laevis oocytes with characteristics that resemble other inward rectifier K+ channels found in other species.

Animals↗