The effect of radiofrequency radiation generated by a Global System for Mobile Communications source on cochlear development in a rat model.

OBJECTIVE: This study aimed to determine the effect of radiofrequency radiation generated by 900 and 1800 MHz Global System for Mobile Communications sources on cochlear development in the rat model. METHODS: Eight pregnant albino Wistar rats were divided into three groups: control, 900 MHz and 1800 MHz. The latter two groups of pregnant rats were exposed to radiofrequency radiation for 1 hour per day starting on the 12th day of pregnancy until delivery. The rats in the control, 900 MHz and 1800 MHz groups gave birth to 24, 31 and 26 newborn rats respectively. Newborn rats in the 900 MHz and 1800 MHz groups were exposed to radiofrequency radiation for 1 hour per day for 21 days after delivery. Hearing evaluations of newborn rats were carried out using distortion product otoacoustic emissions testing. Eight newborn rats were randomly selected from each group for electron microscopic evaluation. RESULTS: Distortion product otoacoustic emission tests revealed no significant difference among the groups, but electron microscopic evaluation revealed significant differences among the groups with regard to the number of normal, apoptotic and necrotic cells. CONCLUSION: The findings indicated cellular structural damage in the cochlea caused by radiofrequency radiation exposure during cochlear development in the rat model.

Direct cardiac effects in isolated perfused rat hearts measured at increasing concentrations of morphine, alfentanil, fentanyl, ketamine, etomidate, thiopentone, midazolam and propofol.

The direct cardiac effects of morphine, alfentanil, ketamine, etomidate, thiopentone, midazolam and propofol were measured in isolated Wistar rat hearts. Experiments were performed using a multiple columnar Langendorff apparatus and the hearts were perfused with a modified Tyrode solution under constant pressure. Each drug was applied from a different column in rising concentrations at 5-min intervals. Dose ranges were chosen to compare effects at sub-clinical, clinically relevant and more than clinical concentrations. Six rat hearts were chosen at random for each drug. Only thiopentone reduced contractile force at a clinically relevant concentration: measured as g contractility per g heart weight-1 (mean +/- standard deviation), base-line contractility was 8.8 +/- 2.4, and contractility at 10(-4) mol litre-1 thiopentone was 7.1 +/- 1.5 (P < 0.01). Alfentanil was the only drug to have no significant effect on the isolated heart at any concentration. Propofol was not cardiodepressant at clinically relevant concentrations, but had a lower therapeutic range than the other drugs.

Comparative assessment of chordal preservation versus chordal resection in mitral valve replacement for mitral stenosis.

Mitral valve replacement with preserving all chordae tendineae in patients with mitral regurgitation has been proved to be beneficial for left ventricular performance in the postoperative period. To evaluate the effectiveness of this technique in patients with mitral stenosis a comparison of the hemodynamic and echocardiographic data between patients having operation with this technique (Group P, n = 15, mean age = 37.5 +/- 12 years), and those having operation with the conventional method of mitral valve replacement (Group C, n = 15, mean age = 39 +/- 10.4 years) was made. The study population was limited to patients who had no clinical evidence of coronary artery disease and if over 40 years of age had normal coronary artery anatomy on coronary arteriography; patients with no evidence of aortic stenosis and/or regurgitation; and patients who had pure mitral stenosis or mitral stenosis with slight regurgitation (Grade 2 or less) with a mean gradient across the mitral valve greater than 10 mmHg. Hemodynamic parameters improved in both groups after the operation. However, echocardiographic measurements obtained six months postoperatively revealed a significant decrease in left ventricular ejection fraction in Group C (61.33 +/- 9.29% preoperatively versus 53.2 +/- 10.3% postoperatively; p < 0.05). The difference between left ventricular ejection fraction diminution of the two groups was statistically significant (-0.71 +/- 6.28% in Group P versus -8.07 +/- 13.35% in Group C; p < 0.01). Left ventricular end systolic and end diastolic dimensions decreased in patients with preserved valves and increased in patients operated on with conventional method without reaching a statistical significance. Sizes of prosthetic valves inserted were in the same range and no significant differences were found in preoperative and postoperative comparison of the two groups in respect to effective mitral orifice area and transvalvular gradient. There were no evidence of prosthetic valve dysfunction and paravalvular leakage and no operative or late deaths. It is concluded that if it is suitable, mitral valve replacement with preservation of chordae tendineae is expected to have a beneficial effect on postoperative left ventricular performance in patients with mitral stenosis.