Gürbüz Çelebi

Electrodiagnostic methods for neurogenic dysphagia

OBJECTIVE Swallowing mechanisms and neurogenic dysphagia have not been systematically studied by the EMG technique. It is desirable to evaluate neurogenic dysphagia for diagnostic and possibly for therapeutic purposes using electrophysiological methods. METHODS The following methods were described: mechanical upward/downward movements of the larynx were detected using a piezoelectric sensor, while submental integrated EMG activity was recorded during dry and wet swallowing. The EMG activity of cricopharyngeal muscle of the upper oesophageal sphincter was also recorded in some normal subjects and patients. Piecemeal deglutition and the dysphagia limit were determined in all patients to detect dysphagia objectively. In this study 75 normal subjects and 177 neurological patients with various degrees of dysphagia were investigated. RESULTS Voluntarily triggered oropharyngeal swallowing was commonly pathological in the majority of patients, with or without overt dysphagia. The dysphagia limit appeared to be an objective measure of the degree of dysphagia in more than 90% of patients. Pathophysiological mechanisms were different in at least three groups of patients with neurogenic dysphagia. In the group of patients with muscular disorders, laryngeal elevators were involved while the CP-sphincter was intact. The second group included patients with the clinical signs of corticobulbar fibre involvement such as amyotrophic lateral sclerosis and pseudobulbar palsy. In these patients, there was incoordination between paretic laryngeal elevators and hyperreflexic CP-sphincter. In the third group (patients with Parkinsons disease), the swallowing reflex was delayed and prolonged. CONCLUSIONS EMG methods described in the present study are very useful for the diagnosis of neurogenic dysphagia, objectively and quickly. They are important to understand the physiological mechanisms for deglutition and its disorders.

An Electronic Device Measuring the Frequency of Spontaneous Swallowing: Digital Phagometer

A new and protable electronic device called the “Digital Phagometer” is described for the time-based counting of spontaneous swallowing. This device is composed of a piezoelectric sensor and a digital event counter/recorder which can be downloaded to any IBM-compatible PC. The sensor of Digital Phagometer is placed and fixed on the coniotomy region between the cricoid and thyroid cartilage. In this way, it is capable of sensing each upward and downward movement of the larynx produced by spontaneous movement as a function of time. Spontaneous swallowing was measured 1–4 h after lunch in 21 normal subjects and 21 patients with Parkinsons disease (PD). The mean frequency of spontaneous swallowing was 0.8 counts/min in PD patients and 1.18 counts/min in normal subjects (p<0.05). During the intake of 200 ml water, the mean frequency of voluntary swallowing did not differ significantly between the two groups (24.6 counts/min in normals vs. 22.3 counts/min in PD patients), but the time necessary to swallow the same volume of water was longer in the PD group.

The classification of human tremor signals using artificial neural network

Tremor is an involuntary movement characterized by regular or irregular oscillations of one or several body segments. Physiological and pathological tremor in motor control can be defined as roughly sinusoidal movements with particular amplitude and frequency profiles. The electrophysiological analysis of human tremor has a long tradition. Tremor time series belongs to stochastic signals. This because the mechanism of generating them is so complex and exposed to so many uncontrollable influence that mathematical equations describing them contain random quantities. In this study, we concerned with tremor classification for the purpose of medical diagnosis. Accelerometer based tremor signals belong to Parkinsonian, essential, and healthy subjects were considered for this aim. Following features were extracted from tremor signals for classification by artificial neural network (ANN); linear prediction coefficients, wavelet transform detail coefficients, wavelet transform based entropy and variance, power ratio, and higher-order cumulants. Scaled-conjugate (SCG) and BFGS (Broyden-Fletcher-Goldfarb-Shanno) gradient learning algorithms were used. Despite BFGS algorithm had more sensitivity value (92.27%), SCG algorithm had more specificity value (89.01%). According to overall performance, BFGS algorithm (91.02%) was better than SCG algorithm (88.48%).

Nonlinear analysis of heart rate variability

This article reports nonlinear analysis of ECG R-R interval time-series obtained from healthy individuals and some cardiac patients. The R-R interval time-series data from 6 healthy individuals and 3 cardiac patients were transformed into multidimensional phase-space vectors by time-delay embedding. The largest Lyapunov exponent and correlation dimension (CD) were calculated. Nonlinearity was tested by comparing the CDs obtained from the original data with those obtained from surrogate data sets. Results are discussed with reference to results obtained in previous studies.

Effects of sibutramine on thermogenesis in obese patients assessed via immersion calorimetry

Glucose utilization studies show that sibutramine-induced thermogenesis is mediated via selective sympathetic activation of brown adipose tissue. The goal of the present study was to use a new calorimetry method in which resting metabolic rate is enhanced to evaluate the effects of sibutramine treatment on thermogenesis. Sixty obese women were included in the study. Subjects were divided into 2 equal groups-the placebo and sibutramine treatment groups. The sibutramine group was given sibutramine 10 mg daily for 12 wk. At baseline and at the end of the 12-wk treatment period, thermogenic measurements were taken with the use of water immersion calorimetry. Subjects were examined at weeks 4, 8, and 12 of treatment to identify adverse effects. Body mass index, measured at 31.5±2.05 kg/m2 in the placebo group, decreased to 30.4±2.94 kg/m2 after 12 wk (P=.07). In the sibutramine group, it decreased from 33.5±4.1 kg/m2 to 30.9±4.8 kg/m2 (P < .05). In the sibutramine group, mean thermogenic response changed from a baseline value of 1.27±0.29 kcal/kg/h to 1.44±0.13 kcal/kg/h after 12 wk of treatment. In the placebo group, the baseline value was 1.56±0.27 kcal/kg/h; it changed to 1.33±0.36 kcal/kg/h at the end of 12 wk. The findings of this study suggest that sibutramine treatment promotes thermogenesis, thus facilitating weight loss. Calorimetry enhances resting metabolism through more efficient heat transfer from the body.

Electrodermal activity in patients with Parkinson's disease

Peripheral sympathetic activity was investigated in 25 Parkinsons disease (PD) patients and 27 healthy subjects by measuring the skin resistance level (SRL) and skin resistance response (SRR) at the palm of the hand during rest, auditory stimulation and patellar tendon tapping. Blood flow to the hand was also monitored. Normal responses were obtained from all the 27 healthy subjects with both stimuli. All but one of the 25 PD patients responded to sound, six patients failed to respond to patellar tendon tapping and one patient failed to respond to both stimuli. The SSRs (when detectable) of PD patients were always smaller in amplitude than those of normal subjects. It was also observed that while an electrodermal response was present, no vasomotor response could be elicited by either stimulus in some patients. The opposite was true in some other patients. When response latencies were evaluated, it was found that although the mean latency of the SRRs evoked by tendon tapping was shorter than the mean latency of responses to auditory stimuli in normal subjects, this was not the case in PD patients. SRR mean latency to patellar tendon tapping was significantly longer in PD patients compared with that in normal subjects. Mean latencies of responses to auditory stimuli were the same for both normal subjects and patients. The ratio of the SRR amplitude to SRL (i.e. relative change in SRL) during both types of stimulation was significantly smaller in PD patients than in normal subjects. All the above findings were also true when blood flow to the tissue was interrupted briefly. These findings support the conjecture that the abnormal peripheral sympathetic neural responses associated with PD may arise from a functional disorder in the basal ganglia that influence the efferent autonomic pathway, from impairment of the intermediolateral column of the spinal cord, and possibly from cognitive deficits.

Pressure distribution on the wall of experimental aneurysms

SummarySince it is known that turbulent flow exists in aneurysms, we have investigated whether pressure might be distributed unevenly on the aneurysmal wall, and whether it varies with the shape and size of the aneurysm and its orifice diameter as well as with the direction of blood flow in the parent vessel. It was found that in some instances, such as with aneurysms having narrow necks and situated at 90 degrees to the parent vessel blood flow, aneurysmal pressure is relatively low.

Early menopause association with employment, smoking, divorced marital status and low leptin levels.

Aims. The aims of this study were (1) to investigate the determining risk factors related to early menopause and (2) to compare the relationships between demographic characteristics and hormonal status and leptin levels in subjects with early (no surgical) and natural menopause. Study design. The prospective study was conducted on 500 women with early and 2700 women with natural menopause. Detailed information was collected about their employment status, past and present smoking habits, coffee and alcohol use, educational level and other factors relevant to health. Thirty participants with early menopause and 30 participants with natural menopause were evaluated for hormone and leptin levels. Results. Employment status (OR: 1.94), current smoking (OR: 1.80) and divorced marital status (OR: 1.79) were found to be significant risk factors for early menopause. Mean levels of leptin in natural and early menopause were measured 11.40 ± 4.1 ng/ml and 8.01 ± 3.9 ng/ml, respectively (p = 0001). Leptin levels in the early (r = 0.765, p = 0.001) and natural (r = 0.750, p = 0.001) menopause subjects correlated positively with oestradiol (E2) levels. Conclusion. This study shows that early onset of menopause is correlated with smoking, employment status, divorced marital status and lower leptin levels.

Investigation of the effects of 50 Hz magnetic fields on platelet aggregation using a modified aggregometer

Purpose: Electromagnetic fields have various effects on intracellular calcium levels, free oxygen radicals and various enzymes. The platelet activation pathway involves an increase in intracellular calcium levels and protein kinase C activation; and free oxygen radicals play a mediating role in this pathway. This study investigated whether 1 mT and 6 mT, 50 Hz magnetic fields had any effects on platelet aggregation. Materials and Methods: Blood from healthy volunteers was anticoagulated with either citrate or heparin. Each sample was divided in half and assigned to exposure and control groups. Platelet rich plasma samples in the exposure group were exposed to a 1 mT or a 6 mT, 50 Hz magnetic field for 1.5 or 1 h, respectively. The samples from both exposure and control groups were simultaneously evaluated using a modified optical aggregometer. Adenosine-diphosphate, collagen, and epinephrine were used as inducing agents. The slopes of the aggregation curve, the maximum values and the areas under the curves were recorded and compared. Results: A significant effect was observed only in the 1 mT-citrate group. It was found that magnetic field exposure significantly increased the maximum values and slopes of the collagen-induced aggregations. Conclusions: It was found that magnetic field exposure has an activating effect on platelet aggregation.

Automatic detection and classification of crackles by using a neural network

In this study a neural network has been Implemented to detect and classify crackle signals. The system has been observed to be superior to systems employing time domain features.