[Genetic study of the vasovagal syncope associated to the Arg389Gly polymorphism of the beta1 adrenergic receptor]. / Estudio genético del síncope vasovagal asociado al polimorfismo Arg389Gly del receptor adrenérgico beta1.

The purpose of this study was to evaluate the correlation between the vasovagal syncope (VVS) and the beta1 adrenergic receptor polymorphism at the 389 position. Seventy individuals with VVS were selected. DNA was extracted from peripheral blood by salting out and subjected to the amplification-restriction test. Genotype identification was made by polyacrylamide gel electrophoresis. A higher frequency in genotype and allele frequencies were found in individuals with positive tilted table test respect individuals with negative test, as well as a marked preference of the GlyGly phenotype in women. Genotype Arg389Gly was the most frequent between individuals with positive response in passive phase with respect to those in the induced phase. When the genotype was analyzed based on the hemodynamic response (VASIS) a gradient is observed in the frequency of Arg389Gly with the highest major frequency in the cardio-inhibitory response followed by the mixed response, and finally the vasodepressor response. These results suggest that the SVV has a genetic component associated with the Arg389Gly polymorphism of the adrenergic receptor. The Gly allele has a high risk association and it is maintained in the population through heterozygosis.

Personal exposure to PM2.5 air pollution and heart rate variability in subjects with positive or negative head-up tilt test.

Particulate matter air pollution has been related to an increase in cardiopulmonary morbidity and mortality especially in susceptible subjects with a known cardiopulmonary disease. Recent studies suggest that PM(2.5) air pollution was associated with changes in heart rate variability (HRV). The purpose of this study was to identify and compare changes in HRV in positive or negative head-up tilt (HUT) participants. Fifty two subjects, 31 women and 21 men, 20-40 years old, underwent PM(2.5) personal monitoring and Holter-ECG monitoring in supine and orthostatic position, during active standing, in indoor and outdoor environments. All measurements were made between 8 and 11 AM in the same geographical location (southeast of Mexico City). Frequency domain indexes were estimated in absolute (ms(2)) and in normalized units (nu) (low frequencies (LF), high frequencies (HF) and low/high frequency ratio (LF/HF)) in 5 min periods by standard methods. Data were transformed into natural logarithmic scale (ln). Comparisons were made between genders and positive and negative HUT subjects. LF were larger and HF were smaller in negative HUT males. Multivariate analysis with GEE models, adjusted for each index, showed a significant decrease of HRV (LFln -0.194 95% CI, -0.4509, 0.0627, and HFln -0.298 95% CI, -0.5553, -0.0401) associated to an increase in PM(2.5) air pollution in positive and negative HUT subjects which was larger for HFln in outdoor environments. PM(2.5) air pollution was associated with changes in HRV in positive and negative HUT subjects without cardiopulmonary disease.

Estudio genético del síncope vasovagal asociado al polimorfismo Arg389Gly del receptor adrenérgico beta1 / Genetic study of the vasovagal syncope associated to the Arg389Gly polymorphism of the beta1 adrenergic receptor

The purpose of this study was to evaluate the correlation between the vasovagal syncope (VVS) and the beta1 adrenergic receptor polymorphism at the 389 position. Seventy individuals with VVS were selected. DNA was extracted from peripheral blood by salting out and subjected to the amplification-restriction test. Genotype identification was made by polyacrylamide gel electrophoresis. A higher frequency in genotype and allele frequencies were found in individuals with positive tilted table test respect individuals with negative test, as well as a marked preference of the GlyGly phenotype in women. Genotype Arg389Gly was the most frequent between individuals with positive response in passive phase with respect to those in the induced phase. When the genotype was analyzed based on the hemodynamic response (VASIS) a gradient is observed in the frequency of Arg389Gly with the highest major frequency in the cardio-inhibitory response followed by the mixed response, and finally the vasodepressor response. These results suggest that the SVV has a genetic component associated with the Arg389Gly polymorphism of the adrenergic receptor. The Gly allele has a high risk association and it is maintained in the population through heterozygosis.