Enhanced external counterpulsation improves endothelial function and exercise capacity in patients with ischaemic left ventricular dysfunction

Enhanced external counterpulsation (EECP) therapy decreases angina episodes and improves quality of life in patients with left ventricular (LV) dysfunction (LVD). However, studies have not elucidated the mechanisms of action and overall effects of EECP in patients with LVD. The purpose of the present study was to investigate the effects of EECP on endothelial function in peripheral conduit arteries and exercise capacity (peak Vo ₂) in patients with LVD. Patients with ischaemic LVD (ejection fraction (EF) 34.5 ± 4.2%; n = 9) and patients with symptomatic coronary artery disease (CAD) and preserved LV function (EF 53.5 ± 6.6%; n = 15) were studied before and after 35 sessions (1 h) of EECP. Brachial and femoral artery flow‐mediated dilation (bFMD and fFMD, respectively) were evaluated using high‐resolution ultrasound. Enhanced external counterpulsation elicited similar significant improvements in the following FMD parameters in the CAD and LVD groups (P ≥ 0.05 between groups for all): absolute bFMD (+53% and +70%, respectively), relative bFMD (+50% and +74%, respectively), bFMD normalized for shear rate (+70% and +61%, respectively), absolute fFMD (+33% and +21%, respectively) and relative fFMD (+32% and +17%, respectively). In addition, EECP significantly improved plasma levels of nitrate/nitrite (+55% and +28%) and prostacyclin (+50% and +70%), as well as peak Vo ₂ (+36% and +21%), similarly in both the CAD and LVD groups (P ≥ 0.05 between groups for all). Despite reduced LV function, EECP therapy significantly improves peripheral vascular function and functional capacity in CAD patients with ischaemic LVD to a similar degree to that seen in CAD patients with preserved LV function.     

Heritability estimates for beta cell function and features of the insulin resistance syndrome in UK families with an increased susceptibility to Type 2 diabetes

Aims/hypothesis The aim of this study was to measure the heritability estimates for metabolic traits and the features of the insulin resistance syndrome in families with an increased genetic susceptibility to Type 2 diabetes.Methods A total of 811 non-diabetic relatives from 278 pedigrees of northern European extraction in which there was a sib-pair with Type 2 diabetes were recruited and studied at the six Diabetes UK Warren Type 2 diabetes centres. Heritability estimates were calculated, allowing for key covariates (age, sex, BMI and recruitment centre). Values greater than 0.10 were considered statistically significant in comparison to zero.Results Fasting glucose concentration and homeostasis model assessment of pancreatic beta cell function (HOMA %B) had the highest heritability estimates of 0.72 and 0.78 respectively. Heritability estimates for the features of the insulin resistance syndrome (BMI, WHR, systolic and diastolic blood pressure, serum lipids and homeostasis model assessment of insulin sensitivity [HOMA %S]) were also high. The heritability estimate for fasting glucose was markedly higher in the present study (0.77 vs 0.21 adjusted for age and sex; p<0.001) than in a comparable study of families from the same background population but with no increased susceptibility to diabetes. However, the estimates for the features of the insulin resistance syndrome were similar in the two studies.Conclusions/interpretation In families with a high risk of Type 2 diabetes, the heritability estimates for fasting glucose, pancreatic beta cell function and the features of the insulin resistance syndrome were all high. The higher heritability estimate for pancreatic beta cell function suggests that this resource may be most effective when investigating genetic susceptibility to beta cell dysfunction.Abbreviations HOMA %B homeostasis model assessment of beta cell function - HOMA %S homeostasis model assessment of insulin sensitivity - EIR early insulin response     

Body composition and hormonal responses to a carbohydrate-restricted diet

The few studies that have examined body composition after a carbohydrate-restricted diet have reported enhanced fat loss and preservation of lean body mass in obese individuals. The role of hormones in mediating this response is unclear. We examined the effects of a 6-week carbohydrate-restricted diet on total and regional body composition and the relationships with fasting hormone concentrations. Twelve healthy normal-weight men switched from their habitual diet (48% carbohydrate) to a carbohydrate-restricted diet (8% carbohydrate) for 6 weeks and 8 men served as controls, consuming their normal diet. Subjects were encouraged to consume adequate dietary energy to maintain body mass during the intervention. Total and regional body composition and fasting blood samples were assessed at weeks 0, 3, and 6 of the experimental period. Fat mass was significantly (P 相似文献   

Teaching cardiac examination skills

OBJECTIVE: To determine if structured teaching of bedside cardiac examination skills improves medical residents’ examination technique and their identification of key clinical findings. DESIGN: Firm-based single-blinded controlled trial. SETTING: Inpatient service at a university-affiliated public teaching hospital. PARTICIPANTS: Eighty Internal Medicine residents. METHODS: The study assessed 2 intervention groups that received 3-hour bedside teaching sessions during their 4-week rotation using either: (1) a traditional teaching method, “demonstration and practice” (DP) (n=26) or (2) an innovative method, “collaborative discovery” (CD) (n=24). The control group received their usual ward teaching sessions (n=25). The main outcome measures were scores on examination technique and correct identification of key clinical findings on an objective structured clinical examination (OSCE). RESULTS: All 3 groups had similar scores for both their examination technique and identification of key findings in the preintervention OSCE. After teaching, both intervention groups significantly improved their technical examination skills compared with the control group. The increase was 10% (95% confidence interval [CI] 4% to 17%) for CD versus control and 12% (95% CI 6% to 19%) for DP versus control (both P<.005) equivalent to an additional 3 to 4 examination skills being correctly performed. Improvement in key findings was limited to a 5% (95% CI 2% to 9%) increase for the CD teaching method, CD versus control P=.046, equivalent to the identification of an additional 2 key clinical findings. CONCLUSIONS: Both programs of bedside teaching increase the technical examination skills of residents but improvements in the identification of key clinical findings were modest and only demonstrated with a new method of teaching. The authors have no conflicts of interest to declare for this article. Financial support: This study was performed as part of a Faculty Development Program in Clinical Epidemiology and Research sponsored by the Collaborative Research Unit of John H. Stroger Jr. Hospital of Cook County i Rush Medical College.     

Mechanisms underlying the basal forebrain enhancement of top‐down and bottom‐up attention

Both attentional signals from frontal cortex and neuromodulatory signals from basal forebrain (BF) have been shown to influence information processing in the primary visual cortex (V1). These two systems exert complementary effects on their targets, including increasing firing rates and decreasing interneuronal correlations. Interestingly, experimental research suggests that the cholinergic system is important for increasing V1's sensitivity to both sensory and attentional information. To see how the BF and top‐down attention act together to modulate sensory input, we developed a spiking neural network model of V1 and thalamus that incorporated cholinergic neuromodulation and top‐down attention. In our model, activation of the BF had a broad effect that decreases the efficacy of top‐down projections and increased the reliance of bottom‐up sensory input. In contrast, we demonstrated how local release of acetylcholine in the visual cortex, which was triggered through top‐down gluatmatergic projections, could enhance top‐down attention with high spatial specificity. Our model matched experimental data showing that the BF and top‐down attention decrease interneuronal correlations and increase between‐trial reliability. We found that decreases in correlations were primarily between excitatory–inhibitory pairs rather than excitatory–excitatory pairs and suggest that excitatory–inhibitory decorrelation is necessary for maintaining low levels of excitatory–excitatory correlations. Increased inhibitory drive via release of acetylcholine in V1 may then act as a buffer, absorbing increases in excitatory–excitatory correlations that occur with attention and BF stimulation. These findings will lead to a better understanding of the mechanisms underyling the BF's interactions with attention signals and influences on correlations.