High Accuracy of Automatic Detection of Atrial Fibrillation Using Wavelet Transform of Heart Rate Intervals

DUVERNEY, D., et al. : High Accuracy of Automatic Detection of Atrial Fibrillation Using Wavelet Transform of Heart Rate Intervals. Permanent and paroxysmal AF is a risk factor for the occurrence and the recurrence of stroke, which can occur as its first manifestation. However, its automatic identification is still unsatisfactory. In this study, a new mathematical approach was evaluated to automate AF identification. A derivation set of 30 24-hour Holter recordings, 15 with chronic AF (CAF) and 15 with sinus rhythm (SR), allowed the authors to establish specific RR variability characteristics using wavelet and fractal analysis. Then, a validation set of 50 subjects was studied using these criteria, 19 with CAF, 16 with SR, and 15 with paroxysmal AF (PAF); and each QRS was classified as true or false sinus or AF beat. In the SR group, specificity reached 99.9%; in the CAF group, sensitivity reached 99.2%; in the PAF group, sensitivity reached 96.1%, and specificity 92.6%. However, classification on a patient basis provided a sensitivity of 100%. This new approach showed a high sensitivity and a high specificity for automatic AF detection, and could be used in screening for AF in large populations at risk.     

Atrial Natriuretic Factor Release During Exercise in Patients Successively Paced in DDD and Rate Matched Ventricular Pacing

Dual chamber pacemakers were implanted in nine patients with permanent second or third degree AV block feight had complete retrograde block). Two identical exercise tests were performed after at least 1 month after implantation. During the first test (T₁) the pacemaker was programmed to the DDD mode and heart rates were recorded every 15 to 30 seconds during exercise and 30 minutes after exercise. Following 30 minutes of rest, the implanted pacemaker was programmed to the VVT mode and driven by an external pacemaker via a skin electrode. The second exercise test (T₂) was then performed and the rate of the external pacemaker was progressively changed to reproduce exactly the rate observed during T₁ at the same exercise stress. Atrial natriuretic factor (ANF) levels were determined at rest, at regular intervals during exercise, and 30 minutes after exercise. ANF levels and release were statistically higher during rate matched ventricular, than DDD pacing. It is concluded that preservation of AV synchrony reduces ANF release induced by heart rate acceleration during exercise.     

Augmentation of neutrophilic granulocyte progenitors in the bone marrow of mice with tumor-induced neutrophilia: cytochemical study of in vitro colonies

Transplantation of CE mammary carcinoma into mice has been shown to produce marked neutrophilia. Previous studies in vivo indicated a significant increase in marrow neutrophil production in these mice, but regulatory mechanisms of this neutrophilia have not been well understood. In order to obtain information about neutrophil production mechanisms at the progenitor cell level, the profile of marrow granulocyte-macrophage progenitors in mice with neutrophilia induced by this tumor was quantitatively analyzed by cytochemical staining of in vitro colonies to distinguish colonies of neutrophils (N-colony), macrophages (M-colony), and mixed cells (NM-colony). Cell cycle kinetics of progenitors were studied by in vivo administration of cytocidal drugs. The absolute number of N-colonies in a femur increased significantly and reached three times normal three to four weeks after tumor implantation. The number of NM-colonies also increased significantly by the fourth week, but the number of M-colonies was unchanged. The number of N-colonies in a femur related directly to the degree of neutrophilia. The increased number of N-colonies from the marrow of tumor-bearing mice was not attributed to a different time course of colony growth nor to a different sensitivity to CSA; instead, a significantly larger fraction of neutrophilic progenitors from the tumor-bearing mice were in active cell cycle than were those of normal mice. The day 14 tumor-bearing mouse serum demonstrated N-colony stimulating activity while the sera of normal mice and day 7 tumor- bearing mice were inhibitory for in vitro colony growth. These studies demonstrated an increase in the numbers and turnover rate of marrow neutrophilic progenitors in CE tumor-induced neutrophilia, suggesting that this tumor stimulates proliferation of these progenitors in vivo.     

Elevated serum levels of neopterin in adult patients with polymyositis/dermatomyositis

We determined serum concentrations of neopterin, soluble tumour necrosis factor (55 kDa) receptor (sTNF-R) and soluble interleukin-2 receptor (sIL-2R) in plasma of 44 patients with polymyositis (PM)/dermatomyositis (DM), including 15 patients with primary PM, 13 patients with primary DM, and 16 patients with myositis and systemic sclerosis in overlap. Concentrations of neopterin, sTNF-R and sIL-2R were measured using commercially available immunoassays. Serum neopterin was increased in 35 of 44 PM/DM patients (80%), sTNF-R in 14 (32%) and sIL-2R in 18 (41%) patients, respectively. There were significant correlations between serum neopterin and sTNF-R, sIL-2R and erythrocyte sedimentation rate (all P < 0.001). Neopterin, as well as sTNF-R and sIL-2R, did not correlate with clinical (neuromuscular and activities of daily living scores) and laboratory (creatine kinase levels) manifestations of myositis. Increased serum levels of neopterin were associated with non-muscular manifestations of PM/DM. In conclusion, serum neopterin appears to be a useful laboratory marker for ongoing immune activation and global disease activity in PM/DM.      

Hippocampal glutamate-glutamine (Glx) in adults with Down syndrome: a preliminary study using in vivo proton magnetic resonance spectroscopy (1H MRS)

Background

Down syndrome (DS), or trisomy 21, is one of the most common autosomal mutations. People with DS have intellectual disability (ID) and are at significantly increased risk of developing Alzheimer’s disease (AD). The biological associates of both ID and AD in DS are poorly understood, but glutamate has been proposed to play a key role. In non-DS populations, glutamate is essential to learning and memory and glutamate-mediated excitotoxicity has been implicated in AD. However, the concentration of hippocampal glutamate in DS individuals with and without dementia has not previously been directly investigated. Proton magnetic resonance spectroscopy (¹H MRS) can be used to measure in vivo the concentrations of glutamate-glutamine (Glx). The objective of the current study was to examine the hippocampal Glx concentration in non-demented DS (DS-) and demented DS (DS+) individuals.

Methods

We examined 46 adults with DS (35 without dementia and 11 with dementia) and 39 healthy controls (HC) using ¹H MRS and measured their hippocampal Glx concentrations.

Results

There was no significant difference in the hippocampal Glx concentration between DS+ and DS-, or between either of the DS groups and the healthy controls. Also, within DS, there was no significant correlation between hippocampal Glx concentration and measures of overall cognitive ability. Last, a sample size calculation based on the effect sizes from this study showed that it would have required 6,257 participants to provide 80% power to detect a significant difference between the groups which would indicate that there is a very low likelihood of a type 2 error accounting for the findings in this study.

Conclusions

Individuals with DS do not have clinically detectable differences in hippocampal Glx concentration. Other pathophysiological processes likely account for ID and AD in people with DS.