Angiotensin-converting enzyme gene variant and its levels: risk factors for myocardial infarction in a South Indian population

INTRODUCTION

Recently, there has been increasing evidence that genetic variation in the angiotensin-converting enzyme (ACE) plays an important role in myocardial infarction. Therefore, the present study was carried out with the aim of investigating the association of the ACE gene insertion/deletion (I /D) polymorphism and its levels in myocardial infarction patients and their first-degree relatives (FDRs).

METHODS

206 patients with myocardial infarction, 168 FDRs and 210 control subjects were enrolled in the study. ACE I /D polymorphism was determined using the polymerase chain reaction method. Serum ACE levels were measured using the photometric method.

RESULTS

The DD genotype and ACE activity were significantly higher in patients (p-value is 0.00006 and 0.0001, respectively) and FDRs (p-value is 0.003 and 0.04, respectively) compared with the controls.

CONCLUSION

ACE DD genotype and ACE levels are important risk factors for myocardial infarction. This study indicates that the higher frequency of the DD genotype and ACE levels observed in FDRs may increase susceptibility to developing myocardial infarction.

Regulation of cytokine gene expression in experimental autoimmune encephalomyelitis

We previously reported that recovery of Lewis rats from experimental autoimmune encephalomyelitis (EAE) is associated with the appearance of suppressor T cells (Ts). These Ts secrete TGF-beta which down-regulates the production of inflammatory cytokines by the effector T cells that mediate this disease. In the present study, we immunized Lewis rats with myelin basic protein (MBP)+CFA, and evaluated purified T cells and MBP-activated spleen cells (SpC) during the paralytic phase (day 12) and after recovery (days 30-33) for TGF-beta and interferon (IFN)-gamma mRNA. We used reverse transcriptase-polymerase chain reaction (RT-PCR), quantitated on the basis of beta-actin mRNA. Abundant IFN-gamma mRNA was present in MBP-activated SpC obtained on day 12. In contrast, only trace IFN-gamma mRNA was detected in day 30 activated SpC, and no IFN-gamma mRNA was present in purified, nonactivated T cells obtained at either time. The level of IFN-gamma mRNA correlated with secretion of IFN-gamma as determined by ELISA on SpC culture supernatants, and with severity of adoptively transferred EAE by the activated SpC. Thus, it appears that IFN-gamma mRNA is both transcribed and translated in response to antigen activation, resulting in secretion of IFN-gamma by the disease-inducing Te. In contrast, when we used RT-PCR to investigate the expression of TGF-beta mRNA, we found the transcript present in isolated T cells and MBP-activated SpC obtained from rats at both days 12 and 30. The presence of TGF-beta mRNA at time points corresponding to both clinical EAE and recovery suggests post-transcriptional regulation of the production of this immunoregulatory cytokine.

Left ventricular performance in coronary artery disease evaluated with systolic time intervals and echocardiography

Simultaneous determinations of systolic time intervals (preejection period index [PEPI], left ventricular ejection time index [LVETI] and ratio of preejection period to left ventricular ejection time [PEP/LVET]) and echographic measures of left ventricular performance (percent change in minor axis diameter [%delta D], circumferential shortening rate [Vcf] and end-diastolic diameter [Dd]) were obtained in 25 normal subjects and 37 patients with previously documented transmural myocardial infarction. The group with previous infarction demonstrated significant (P less than 0.001) differences from the normal group in each of the noninvasive measures. PEP/LVET and %deltaD were the most sensitive measures of left ventricular dysfunction. Deviation from the normal range in these measures occurred, respectively, in 70 and 65 percent of patients without dyspnea or fatigability (20 patients) and 85 percent of those without angina pectoris (13 patients). Abnormalities in systolic time interval and echocardiographic measures were related to the severity of dyspnea and fatigability but not to that of angina. Neither the presence of phonocardiographically documented third or fourth sound gallops nor an abnormal cardiothoracic ratio by chest roentgenogram reliably detected patients with abnormal left ventricular performance. The range of abnormality in left ventricular performance did not differ between patients with prior anterior or diaphragmatic myocardial infarction. The frequency of abnormal performance was greatest among patients with combined sites of prior infarction. Among 26 patients studied by coronary arteriography, abnormal left ventricular performance as determined by values for PEP/LVET and %deltaD occurred in fewer than 30 percent of those with 70 percent or greater obstruction of one coronary artery and in more than 80 percent of those with two or three vessel involvement. There was a high correlation between systolic time intervals, %delta D and Vcf, the closest correlation occurring between PEP/LVET and %deltaD (r = -0.93). These data document the sensitivity of the noninvasive systolic time intervals and echographic measures and their superiority over current clinical bedside methods in evaluating left ventricular performance in patients with prior myocardial infarction.