Association analysis of genes in the renin‐angiotensin system with subclinical cardiovascular disease in families with Type 2 diabetes mellitus: The Diabetes Heart Study

Aims Cardiovascular disease (CVD) is a major complication of Type 2 diabetes mellitus. The renin‐angiotensin system (RAS) and nitric oxide production are both important regulators of vascular function and blood pressure. Genes encoding proteins involved in these pathways are candidates for a contribution to CVD in diabetic patients. We have investigated variants of the angiotensinogen (AGT), angiotensin converting enzyme (ACE), angiotensin type 1 receptor (AT1R) and endothelial nitric oxide synthase (NOS3) genes for association with subclinical measures of CVD in families with Type 2 diabetes mellitus (T2DM). Methods Atherosclerosis was measured by carotid intima‐media thickness and calcification of the carotid and coronary arteries in 620 European Americans and 117 African Americans in the Diabetes Heart Study. Because of the role of these systems in blood pressure regulation, blood pressure was also investigated. Results Compelling evidence of association was not detected with any of the SNPs with any outcome measures after adjustments for covariates despite sufficient power to detect relatively small differences in traits for specific genotype combinations. Conclusions Genetic variation of the RAS and NOS3 genes do not appear to strongly influence subclinical cardiovascular disease or blood pressure in this diabetic population.     

Platelet cold agglutinins: a flow cytometric analysis.

Spontaneous EDTA-independent cold platelet agglutination is a rare phenomenon that produces pseudothrombocytopenia when blood samples are analyzed in automated cell counters. We report a case of platelet cold agglutinins and an analysis by flow cytometry. A 49 year old woman presented with abnormal vaginal bleed secondary to uterine fibroids. Platelet clumping was observed in blood samples taken in EDTA-, heparin- and citrate-containing tubes. In flow cytometric tests, patient serum agglutinated 16% of normal platelets at 22 degrees C, and 7% of platelets after incubation at 37 degrees C; in contrast, 3% and < 1% of platelets were agglutinated at 22 and 37 degrees C, respectively, after incubation with normal serum. Minimal agglutination (< 10%) was observed with patient serum at a titre of 1:5 or at temperatures > 30 degrees C. After incubation at 4 degrees C, IgM antibody and C3 were increased on the patient's platelets; no significant amount of IgM or C3 was detected on normal platelets. The specificity of the platelet cold agglutinin was determined by competitive inhibition by monoclonal anti-CD41(GPIIbIIIa). Before the addition of monoclonal antibody, patient's serum agglutinated 16% of normal platelets at 22 degrees C; after addition of anti-CD41 only 2% of the platelets were agglutinated. This blocking effect was not observed with anti-CD42. The patient's platelets functioned normally as determined by CD62 and CD63 expression in response to thrombin, normal platelet aggregation in response to collagen, ADP, and ristocetin, and a normal template bleeding time. In summary, platelet agglutination by a platelet cold agglutinin was quantitated by flow cytometry, the responsible antibody was characterized as a low titre IgM with minimal activity > 30 degrees C, and competitive binding studies supported the GPIIbIIIa complex as the binding site for the antibody. Since the antibody did not affect platelet function, we believe that these patients will not suffer complications from their platelet cold agglutinin, but it could pose a problem under circumstances such as cardiac surgery with hypothermia.     

Coronary venous retroperfusion of arterial blood for the treatment of acute myocardial ischemia

Synchronized coronary venous retroperfusion of autologous arterial blood was offered to patients referred for medically refractory unstable angina or evolving myocardial infarction with contraindications to thrombolytic therapy. Primary endpoints of angina, ST segment deviation, and two-dimensional echocardiographic systolic wall motion were followed to determine the efficacy of retroperfusion in patients prior to and then during angioplasty, surgical intervention, or pharmacological management, as the clinical picture warranted. Over a 12 month period, 21 patients were referred and 15 received retroperfusion. All experienced full relief of angina (p = 0·008). ST segment deviations and systolic wall motion of ischemic zones were observed to improve (p = 0·06 ST changes; p = 0·0001 wall motion changes) with synchronized retrograde perfusion. During attempts to remove patients from retroperfusion, statistically significant (p < 0·01) reproducible changes in these same endpoints were documented. Retroperfusion appears to improve acute myocardial ischemia. This technique functions well in the intensive care unit environment with only fluoroscopy as technical imaging support.     

Codistribution of a sensory gating deficit and schizophrenia in multi-affected families.

Because the clinical diagnosis of schizophrenia has not generally been an adequate phenotypic marker to detect the genes that convey risk for schizophrenia, efforts have been directed toward the identification of more elementary neuronal dysfunctions in schizophrenic patients and their families. Psychophysiological studies of sensory gating and selective attention suggest that defects in these brain functions are present in schizophrenic patients and some of their relatives. This study examines one of these defects in sensory gating, failure to suppress the P50 evoked response to repeated auditory stimuli. Six pedigrees, chosen because of the presence of large sibships containing several cases of schizophrenia, were studied. A mathematical model was developed to assess the familial association of the P50 defect with schizophrenia. The model preserves the quantitative nature of the data and is suitable for use in a sample with small numbers of pedigrees comprising many individuals. It is thus suitable for the evaluation of putative phenotypes in families to be studied by linkage analysis with polymorphic genetic markers. The results suggest that the P50 defect is familially associated with schizophrenia.     

Gating of the Auditory Evoked Potential in Children and Adults

Auditory evoked potentials were recorded from 163 subjects, aged IS months to 55 years. A conditioning-testing paradigm was used to assess sensory gating. In this paradigm, click stimuli are presented in pairs to the subjects with a 0.5-second intrapair interval. In normal adults, the first stimulus activates or “conditions” sensory gating mechanisms. The strength of these mechanisms is “tested” by the second stimulus, which produces a response whose amplitude is significantly suppressed. This aspect of sensory gating was not reliably observed in our subjects until age 18 years. Younger subjects varied widely in their ability to demonstrate sensory gating. Mean levels of suppression increased during late childhood and adolescence, with no relationship to other changes in evoked potential amplitude and latency. Sensory gating would appear to be a late developing aspect of human sensory physiology.     

Cellular immune mechanisms in chronic autoimmune thrombocytopenic purpura (ATP).

Chronic autoimmune thrombocytopenic purpura (ATP) is a common autoimmune-mediated bleeding disease in which autoantibodies are directed against platelets, resulting in their enhanced Fc-mediated destruction by macrophages in the spleen. While there has been extensive studies relating to the autoantibodies in this autoimmune disorder, relatively few have dealt with cell-mediated immunoregulation of the anti-platelet autoantibody response. Nonetheless, there is accumulating evidence that suggests the production of these anti-platelet autoantibodies is under the influence of several abnormal lymphocyte-mediated mechanisms, i.e. enhanced anti-platelet T helper cell activity with concomitant reduced T suppressor cell activity. This review focuses on these cellular events and presents a working model which attempts to explain their close interrelationships.     

Cardiovascular risk in parents of children with extreme lipoprotein cholesterol levels: the Bogalusa Heart Study

Fasting serum lipids, lipoprotein cholesterol, and other cardiovascular disease risk factors were examined in 321 natural parents of children with low and/or high levels of beta- and pre-beta-lipoprotein cholesterol. Parents of children from low pre-beta-lipoprotein groups had elevated alpha- and lower pre-beta-lipoprotein cholesterol levels. Parents whose children had high beta-lipoprotein cholesterol levels also had high serum total and beta-lipoprotein cholesterol levels. Parents of children with high levels of both beta- and pre-beta-lipoprotein cholesterol had a high prevalence of both abnormal risk factor levels, as well as clinical evidence of early coronary artery disease (before age 50 years). These observations show that parents of children with high beta- and/or pre-beta-lipoprotein cholesterol levels have greatly enhanced risk for cardiovascular disease, and children mirror their parents' lipoprotein cholesterol levels. These observations emphasize the need for cardiovascular risk evaluation early in life, especially in high-risk families.     

Hormone replacement therapy is associated with increased C-reactive protein in women with Type 2 diabetes in the Diabetes Heart Study.

AIMS: Increased levels of inflammatory biomarkers, especially C-reactive protein (CRP), are associated with increased risk for cardiovascular disease (CVD) events, such as myocardial infarction, stroke, peripheral vascular disease, and sudden cardiac death. Medical interventions that increase CRP levels, such as hormone replacement therapy (HRT) in post-menopausal women, are under increasing scrutiny. The effect of HRT on CRP levels in women with Type 2 diabetes (T2DM) is not well documented, and conflicting conclusions have been reported. The aim of this study was to determine the influence of HRT on women with diabetes in a large cross-sectional study. METHODS: Three hundred and twenty-seven post-menopausal women with T2DM from the Diabetes Heart Study participated. Current use of HRT was determined and serum CRP levels were measured using a high-sensitivity ELISA kit. Generalized estimating equation methods were used to assess the relationship of multiple clinical and lifestyle (e.g. smoking) measures on CRP levels including differences between women taking HRT (HRT+) and not taking HRT (HRT-). RESULTS: Overall serum CRP levels were strongly associated with body mass index (P < 0.0001) and age (P < 0.0001). Of the women, 243 were not using HRT and 84 were using HRT. HRT+ and HRT- women did not differ significantly in measures of clinical traits, with the exception of higher mean low-density lipoprotein cholesterol in HRT- women (P = 0.004). In all models tested, HRT+ women had significantly higher circulating CRP levels, with P-values ranging from 0.0045 to 0.010. CONCLUSIONS: In this study of serum CRP concentration as a function of HRT in women with Type 2 diabetes, there was consistent evidence for increased circulating CRP levels in women receiving oestrogen-containing HRT. Whether HRT-induced increases in CRP can account for the adverse cardiovascular effects of HRT remains to be established; however, based on these data, there is little reason to believe that diabetic women would be spared from such an effect.