Nonlinear analysis of heart rate variability of healthy subjects and patients with chronic obstructive pulmonary disease.

Chronic obstructive pulmonary disease (COPD) is one of the causes of mortality worldwide with an increasing prevalence. Heart rate variability (HRV) reflects the regulation mechanism of the cardiac activity by the autonomic nervous system. The assessment of HRV by using nonlinear methods is more sensitive for the detection of complexity when compared to linear methods. This study aims to get information about the autonomic dysfunction occurred in patients with COPD by analysing the complexity of HRV. Electrocardiogram signals recorded from healthy subjects, patients with moderate COPD and severe COPD (eight subjects per group) were analysed. The HRV signals were acquired from ECG signals. Signals were reconstructed in the phase space and largest Lyapunov exponent (LLE), correlation dimension, Hurst exponent and approximate entropy (ApEn) values were calculated. It has seen that for the patients with COPD LLE, correlation dimension, Hurst exponent and ApEn values were less than control group. According to this, HRV complexity decreases in the presence of COPD. However, there is no significant difference between COPD groups and the severity of COPD has no effect on the chaoticity of the system. The results revealed that autonomic dysfunction occurred in patients with COPD is associated with reduced HRV complexity.

Assessment of in vivo spinal cord conduction velocity in rats in an experimental model of ischemic spinal cord injury.

STUDY DESIGN: Experimental laboratory investigation of spinal cord conductivity alterations in a rat model of ischemic spinal cord injury (SCI). OBJECTIVE: To observe the epidural spinal cord stimulation-induced electromyography responses, and to investigate the possible alterations of spinal cord conduction velocity (SCCV) and compound muscle action potentials (CMAPs) after ischemic SCI in rats. SETTINGS: Adnan Menderes University, Institute of Health Science, Aydin, Turkey. METHODS: SCI was induced by transient occlusion of the abdominal aorta in male Sprague-Dawley rats. Spinal cord histopathology was examined to determine neuronal damage and Tarlov scale was used to grade locomotor functions. Epidural electrical stimulation of spinal cord was performed by monopolar needle electrodes sequentially at L1-L2 and L5-L6 levels, and CMAPs were recorded from the left gastrocnemius muscle by surface electrodes. Amplitudes and durations of CMAPs were evaluated and SCCVs were calculated by analyzing the latency difference of CMAPs. RESULTS: Ischemia-induced SCI resulted in significant reduction of Tarlov scores and a significant decline in number of viable neurons. Similarly, a significant decrement was observed in SCCV following spinal cord ischemia. CONCLUSION: This study demonstrated that measurement of SCCV via epidural electrical stimulation is possible and displays a significant decline after spinal cord ischemia in rats. We suggest that this method can be beneficial to quantify neuronal damage after experimental ischemic SCI.

Measurement of selected indoor physical environmental factors in hairdresser salons in a Turkish City.

OBJECTIVES: The purpose of this study was to determine electromagnetic fields, electric fields, humidity, temperature, and illumination levels in hairdresser salons located in the downtown area of Aydin, Turkey. Also some health problems which could be related with the occupational factors are evaluated. MATERIALS AND METHODS: The study was carried out in 30 hairdresser salons, all of which had been registered within the past 5 years. Electric and electromagnetic fields, illumination, temperature and humidity measurements were determined for hairdryers, hood hairdryers and depilatory heaters in the participating salons. A brief questionnaire about characteristics and the health status of hairdressers and workplace conditions was prepared and administered to the hairdressers at the salons. RESULTS: The mean electric fields of hairdryers, hood hairdryers and depilatory heaters were determined as 518 +/- 74, 1,123 +/- 199, and 648 +/- 146 in V/m, respectively, at 5 cm from the surface of each device. These appliances generate mean electromagnetic fields in excess of 0.25 microT at 5 cm: hand-held hairdryers, 5.0 +/- 0.7 microT; hood hairdryers, 1.6 +/- 0.3 microT; and depilatory heaters 1.9 +/- 0.6 microT. Total average of cumulative electric and electromagnetic fields, measured at a distance of 90 cm from the surface of these three devices was calculated to be 98.8 V/m and 0.5 microT, in the participating salons. CONCLUSIONS: This preliminary study suggests that physical environmental factors in the salons may be contributing to the health problems of the hairdressers, and the electrical equipment in the workplaces may have cumulative electric and electromagnetic effects.

Photosensitization of red blood cell hemolysis by lutetium texaphyrin.

Lutetium (III) texaphyrin photosensitizes postirradiation or "delayed" photohemolysis (DPH) of human and bovine red blood cells at 730 nm by a Type-2 pathway mediated by singlet molecular oxygen. The DPH rate increases with increasing incubation temperature and with the second power of the incident fluence. The experimental DPH curves are in good agreement with a multi-hit kinetics model based on target theory.