Employing TDMA Protocol in Neural Nanonetworks in Case of Neuron Specific Faults.

Many neurodegenerative diseases arise from the malfunctioning neurons in the pathway where the signal is carried. In this paper, we propose neuron specific TDMA/multiplexing and demultiplexing mechanisms to convey the spikes of a receptor neuron over a neighboring path in case of an irreversible path fault existing in its original path. The multiplexing mechanism depends on neural delay box (NDB) which is composed of a relay unit and a buffering unit. The relay unit can be realized as a nanoelectronic device. The buffering unit can be implemented either via neural delay lines as employed in optical switching systems or via nanoelectronic delay lines, i.e., delay flip flops. Demultiplexing is realized by a demultiplexer unit according to the time slot assignment information. Besides, we propose the use of neural interfaces in the NDBs and the demultiplexer unit for detecting and stimulating the generation of spikes. The objective of the proposed mechanisms is to substitute a malfunctioning path, increase the number of spikes delivered and correctly deliver the spikes to the intended part of the somatosensory cortex. The results demonstrate that significant performance improvement on the successively delivered number of spikes is achievable when delay lines are employed as neural buffers in NDBs.

Bortezomib: a new therapeutic option for POEMS syndrome.

OBJECTIVE: POEMS syndrome with its classical five findings (Polyneuropathy, Organomegaly, Endocrinopathy, M protein, and Skin changes) is a rare multisystem disease. Proinflammatory and proangiogenic cytokines play important roles in its pathogenesis. Treatment options are still debated. METHODS: We present a 65-year-old man with POEMS syndrome who was successfully treated with bortezomib. RESULTS: After seven cycles of this protocol, serum M protein level declined to normal range, and near-to-complete remission was achieved. His symptoms of polyneuropathy improved dramatically. CONCLUSION: Bortezomib may be an effective and safe therapeutic option for patients with POEMS syndrome.

Diurnal blood pressure abnormalities are related to endothelial dysfunction in patients with non-complicated type 1 diabetes.

Patients with diabetes have an increased cardiovascular morbidity and mortality despite interventions to prevent these outcomes. Abnormalities in diurnal blood pressure patterns are also associated with excess cardiovascular mortality. The aim of this study was to determine the effects of diurnal blood pressure patterns on endothelial function and oxidative stress in patients with uncomplicated type 1 diabetes mellitus. Thirty-two normotensive and normoalbuminuric type 1 diabetic patients (21 dipper and 11 nondipper) and 37 healthy (27 dipper and 10 nondipper) volunteers underwent 24-h ambulatory blood pressure monitoring. Their endothelial functions were evaluated using flow mediated dilatation (FMD) and by measuring nitric oxide and thiobarbituric acid reactive substances (TBARS). Dippers were defined as subjects who exhibited an average reduction in both systolic and diastolic blood pressure of greater than 10% between day and night periods. Nondipper type 1 diabetic patients and controls had nighttime systolic and diastolic blood pressure values that were significantly higher than those of dipper diabetic patients (p<0.05) and dipper controls (p<0.01). Values of FMD for nondipper diabetic patients (5.12+/-2.2%) were significantly lower than those in dipper diabetic patients (10.19+/-2.5%, p<0.01), nondipper (10.08+/-2.9%, p<0.001) and dipper controls (11.76+/-3.8%, p<0.001). Additionally, levels of TBARS in the dipper diabetic group and dipper controls were significantly lower than those in the nondipper diabetic group (p<0.05). In conclusion, only type 1 diabetic patients with a nondipping pattern of blood pressure exhibited changes that may lead to endothelial dysfunction and atherosclerosis. (Hypertens Res 2008; 31: 2065-2073).

Interaction between C-reactive protein and endothelin-1 in coronary artery disease.

BACKGROUND: Increased concentrations of serum C-reactive protein (CRP) have been reported to predict major cardiovascular events in patients with coronary artery disease (CAD). Increased concentrations of endothelin-1 (ET-1) are also associated with poor prognosis after myocardial infarction. HYPOTHESIS: We tested the hypothesis that ET-1 might contribute to CRP in prediction of adverse outcome in CAD. METHODS: Serum high sensitive CRP and plasma ET-1 levels of 40 patients who have stable CAD and 25 control subjects were measured, and correlation analysis between these molecules was performed. RESULTS: Mean high sensitive CRP was 8.64 +/- 12.73 mg/l, and mean ET-1 was 8.24 +/- 7.06 pg/ml in the CAD group. We found that there was no statistically significant correlation between high sensitive CRP and ET-1 in either CAD group (p = 0.82), or the control group (p = 0.85). In a subgroup of 13 patients who were not under statin treatment, we found a strong correlation between the levels of these molecules (p = 0.01). CONCLUSION: Our study does not clearly support or exclude a link between CRP and ET-1 in patients who have stable CAD.

Peripartum cardiomyopathy presenting with repetitive monomorphic ventricular tachycardia.

A 30-year-old asymptomatic pregnant woman at 38 weeks' gestation was noticed to have repetitive monomorphic ventricular tachycardia. A dilated left ventricle with moderately reduced systolic function was found on echocardiographic examination. To the best of our knowledge, a case of peripartum cardiomyopathy presenting with repetitive monomorphic ventricular tachycardia has not been previously reported.

Inferior vena cava diameter determines left ventricular geometry in continuous ambulatory peritoneal dialysis patients: an echocardiographic study.

BACKGROUND: Changes in left ventricular (LV) geometry are frequent in patients with continuous ambulatory peritoneal dialysis (CAPD). Geometric adaptation of LV to various stimuli was reported to have adverse prognosis. This study aimed to identify independent risk factors, which contribute to the development of LV geometric remodelling in CAPD patients. METHODS: The left ventricles of 69 CAPD patients were classified echocardiographically into four different geometric patterns on the basis of LV mass and relative wall thickness. With respect to volume factor, we measured inferior vena cava (IVC) diameter and its decrease on deep inspiration [collapsibility index (CI)] by echocardiography. We modelled a stepwise multiple regression analysis to determine the predictors of LV geometry. RESULTS: All four geometric models of LV were identified in our group of 69 CAPD patients. Eccentric left ventricular hypertrophy (eLVH) was observed in 32 (46%), concentric LVH (cLVH) in 19 (28%), normal geometry (NG) in 10 (14%) and concentric remodelling (CR) in eight (12%) CAPD patients. Mean IVC index of the eLVH group (10.72 +/- 2.19 mm/m(2)) was significantly higher than corresponding indexes of NG (7.90 +/- 1.54 mm/m(2)), CR (8.51 +/- 1.28 mm/m(2)) and cLVH (8.04 +/- 2.00 mm/m(2)) groups (P < 0.001 for each comparisons). The eLVH group also had significantly lower mean CI value (0.48 +/- 0.11) than CR (0.58 +/- 0.09) and cLVH (0.57 +/- 0.07) groups (ANOVA P = 0.008). Stepwise multiple regression analysis revealed that IVC index, CI and haemoglobin were the independent predictors of LV geometric stratification (R2 = 0.36, P < 0.001). CONCLUSION: Hypervolaemia, identified by IVC index and CI, and anaemia contribute independently to LV geometry in CAPD patients. Echocardiography as a non-invasive tool is not only useful to determine LV geometry, but also to assess the volume status of CAPD patients.

Effect of angiotensin-converting enzyme inhibition on endothelial function and insulin sensitivity in hypertensive patients.

INTRODUCTION: Evidence suggests an association between insulin resistance, hypertension and impaired endothelial function. Studies have shown that insulin resistance precedes the development of hypertension. By improving insulin sensitivity, it may be possible to improve hypertension and the subsequent damage to vessel walls. Some data indicates beneficial effects of angiotensin-converting enzyme (ACE) inhibitors on insulin sensitivity and endothelial function. We aimed to investigate these effects of ACE inhibition in the same group of patients with essential hypertension. MATERIALS AND METHODS: Nine non-smoking, untreated hypertensive patients (38.3+9 years, 4/5 male/female) and 12 age-matched healthy subjects (35.2+6.7 years, 5/7 male/female) were included in the study. Hypertensive patients were given enalapril maleate (5 40 mg/day) for six months. The following parameters were studied at baseline and at the end of treatment period. Whole body insulin sensitivity was measured by a formula derived from an oral glucose tolerance test and named as the insulin sensitivity index (ISI). Insulin was measured by chemiluminescence and glucose by a glucose oxidase method. Endothelial function was evaluated as flow-mediated dilatation (FMD) of the brachial artery by ultrasonography and expressed as a percentage change relative to baseline diameter. Endothelial- independent vasodilatation was measured after sublingual nitroglycerine. RESULTS: FMD was impaired in the hypertensive group compared with healthy subjects (7.3+3.1% vs. 15.3+4.8%, p<0.0005), and ISI values were 1.18+0.6 vs. 4.4+0.9 (p<0.0001) respectively. Both insulin sensitivity and FMD improved after the treatment period compared with baseline values, FMD increased from 7.3+3.1% to 16.0+2.9% (p<0.0005) and ISI from 1.18+0.6 to 4.2+1.0 (p<0.0001). FMD and ISI showed a significant positive correlation (r=0.67, p<0.001) in the hypertensive group. CONCLUSIONS: Patients with essential hypertension have impaired endothelial function and decreased whole body insulin sensitivity compared with healthy subjects. Treatment for six months with enalapril maleate seems to improve both FMD and ISI. This study confirms the beneficial effects of ACE inhibition on both endothelial function and insulin sensitivity tested in the same group of essential hypertensive patients. The mechanism of these favourable effects of ACE inhibition needs to be clarified.

Uncontrolled hypertension due to volume overload contributes to higher left ventricular mass index in CAPD patients.

BACKGROUND: Hypertension (HT) is common in patients on continuous ambulatory peritoneal dialysis (CAPD) and is responsible for increased cardiovascular morbidity and mortality. In this study, we aimed to determine the prevalence of 'uncontrolled HT' during background therapy in CAPD patients by using office measurements and ambulatory blood pressure monitoring (ABPM). We further determined whether intravascular volume status, assessed by inferior vena cava diameter (IVCD) index, contributes to higher blood pressure (BP) and increased left ventricular mass index (LVMI). METHODS: Seventy-four CAPD patients were included in the final analysis. All patients underwent echocardiographic examination and received ABPM. Patients undergoing CAPD were categorized into two groups: 'uncontrolled HT' (Group A) and 'normotensive and controlled HT' (Group B). Intravascular volume status was determined using the IVCD index and collapsibility index (CI) on the same day as ABPM. RESULTS: The prevalence of HT was 84% when using office measurements and 82% when using daytime ABPM. Daytime BP was 147/92 mm Hg by office measurements and 145/91 mm Hg by ABPM (P>0.05). The prevalence of 'uncontrolled HT' measured by ABPM was 73% (n=54). Patients with uncontrolled HT (Group A) were taking more antihypertensive medications than patients with 'normotension and controlled HT' (Group B, n=20; 1.0+/-0.8 vs 0.5+/-0.7, P=0.008). The IVCD index was higher in Group A than in Group B (9.2+/-2.1 vs 7.7+/-1.9 mm/m(2), P=0.007). There was no correlation between IVCD index and office BP, ABPM measurements or LVMI. The LVMI was also higher in Group A than in Group B (145+/-39 vs 118+/-34 g/m(2), P<0.01). Stepwise multiple regression analysis revealed that 24 h diastolic BP and haemoglobin were independent determinants of LVMI. CONCLUSION: Uncontrolled HT on background therapy is highly prevalent among volume overloaded CAPD patients. Further long-term prospective studies examining effects of salt restriction and ultrafiltration on BP control and left ventricle wall thickness are warranted.

QT dispersion in renal transplant recipients.

An increased QT dispersion (QTd) is associated with a variety of cardiac diseases and predicts sudden death. Although chronic renal failure patients and patients on hemodialysis are shown to have an increased QTd, evidence of increased QTd in renal transplant patients is scarce. In this study, renal transplant patients were evaluated to find out if they had an increased QTd. Thirty-four renal transplant recipients aged 35 +/- 8 years and 34 healthy control subjects aged 34 +/- 8 years were included in the study. The mean time after transplantation was 51.8 +/- 40.4 (range 5-154) months. The QT interval was measured by 12-lead electrocardiogram, and the QTd was defined as the difference between the maximum and minimum QT interval. Bazett's formula was used to correct for the heart rate (QTc). Both QTd and QTc dispersion (QTcd) in renal transplant patients were compared with those of control subjects. All patients underwent transthoracic echocardiographic assessment and 24-hour ambulatory blood pressure monitoring. Renal transplant recipients had similar QTd (37 +/- 15 vs. 39 +/- 17 ms) and QTcd (50 +/- 18 vs. 55 +/- 20 ms) compared to control subjects. QTd and QTcd were similar in patients with and without left ventricular hypertrophy (QTd 37 +/- 14 vs. 36 +/- 17 ms and QTcd 50 +/- 14 vs. 49 +/- 21 ms, respectively). No association was found between QTd and left ventricular mass index or blood pressure measurements. The QTd was not found to be increased in renal transplant recipients as compared with that of healthy controls in this study. Normalization of the QTd after renal transplantation may be through the correction of several factors responsible for increased QTd in uremic patients.