Ultraviolet radiation properties as applied to photoclimatherapy at the Dead Sea.

BACKGROUND: The Dead Sea basin, the lowest terrestrial point on earth, is recognized as a natural treatment center for patients with various cutaneous and rheumatic diseases. Psoriasis is the major skin disease treated at the Dead Sea with excellent improvement to complete clearance exceeding 85% after 4 weeks of treatment. These results were postulated to be associated with a unique spectrum of ultraviolet radiation present in the Dead Sea area. METHODS: The UVB and UVA radiation at two sites is measured continuously by identical sets of broad-band Solar Light Co. Inc. meters (Philadelphia, PA). The spectral selectivity within the UVB and UVA spectrum was determined using a narrow-band spectroradiometer, UV-Optronics 742 (Orlando, FL). The optimum exposure time intervals for photoclimatherapy, defined as the minimum ratio of erythema to therapeutic radiation intensities, were also determined using a Solar Light Co. Inc. Microtops II, Ozone Monitor-Sunphotometer. RESULTS: The ultraviolet radiation at the Dead Sea is attenuated relative to Beer Sheva as a result of the increased optical path length and consequent enhanced scattering. The UVB radiation is attenuated to a greater extent than UVA and the shorter erythema UVB spectral range decreased significantly compared with the longer therapeutic UVB wavelengths. CONCLUSIONS: It was demonstrated that the relative attenuation within the UVB spectral range is greatest for the shorter erythema rays and less for the longer therapeutic UVB wavelengths, thus producing a greater proportion of the longer therapeutic UVB wavelengths in the ultraviolet spectrum. These measurements can be utilized to minimize the exposure to solar radiation by correlating the cumulative UVB radiation dose to treatment efficacy and by formulating a patient sun exposure treatment protocol for Dead Sea photoclimatherapy.

Treatment of psoriasis at a Dead Sea dermatology clinic.

BACKGROUND: The Dead Sea, with its unique optical, chemical, and atmospheric properties, provides an effective alternative treatment for psoriasis. METHODS: The records of 1448 consecutive psoriasis patients treated at a Dead Sea psoriasis clinic were retrospectively evaluated concerning their treatment response and demographic characteristics. RESULTS: Clearing of 80-100% was observed in 88% of the patients treated, including almost 58%, who had complete clearing. The demographic data studied that included gender, previous treatment at the Dead Sea, prior history of hospitalization for psoriasis, prior PUVA treatment, or a history of arthritis did not reveal any significant relationships, although overseas patients responded considerably better than Israelis. CONCLUSIONS: The overall response in a large cohort of psoriasis patients treated at the Dead Sea was excellent. Further prospective studies and basic investigations are essential to understand the mechanism(s) involved and the relationships between other demographic data and the treatment response.

Ventricular and atrial defibrillation using new transvenous tripolar and bipolar leads with 5 French electrodes and 8 French subcutaneous catheters.

This study evaluated the use of new small transvenous atrial and ventricular leads for converting atrial fibrillation (AF) and ventricular fibrillation (VF) in 10 adult male mongrel dogs. Five dogs (group A) received a right atrial "J" (AJ) and right ventricular (RV) active fixation tripolar lead, each consisting of a platinized platinum pacing tip, anode band, and braided defibrillation electrode. The remaining five dogs (group B) received one bipolar RV lead and one tripolar AJ lead. The RV leads were implanted in the right ventricular apex (RVA) and the AJ leads were placed in the atrial appendage. Additionally all dogs received two 8 French subcutaneous defibrillation catheters in the fifth and seventh intercostal spaces. Twenty asymmetric biphasic shocks consisting of five randomized voltage levels were used to convert VF in groups A and B. The bipolar RV lead (group B) had a significantly higher probability of success in converting VF than the tripolar RV lead (group A). In group A defibrillation thresholds for converting AF were obtained using two electrode configurations. No significant difference was observed between the two electrode configurations used to convert AF. Pacing and sensing thresholds were satisfactory for bipolar and tripolar lead configuration.

Efficacy and safety of monophasic and biphasic waveform shocks using a braided endocardial defibrillation lead system.

Endocardial lead systems for implantable cardioverter-defibrillators utilize large (12F) rigid catheters with spring defibrillation electrodes, and lead system failure has been observed during long-term implant. We evaluated a novel flexible 8F braided electrode catheter for pacing and defibrillation in canine experiments. Active fixation and pacing were accomplished using a screw-in distal electrode, and defibrillation pulses were delivered through a braided electrode. Two braided electrode catheters were positioned in the right ventricular apex (6 cm2) and in the superior vena cava-right atrial junction (5 cm2), respectively. An elliptical 13 cm2 surface area patch electrode was positioned along the left lateral cardiac border. Ventricular fibrillation (VF) was induced and monophasic and asymmetric biphasic shocks (leading voltages 260 to 1000 V) were delivered via dual and triple electrode configurations in each animal using a prospective randomized crossover study design. Mean right ventricular pacing threshold was 0.5 +/- 0.2 mA, with a mean electrogram amplitude of 11.1 +/- 2.8 mV during sinus rhythm prior to fibrillation and defibrillation. Two hundred seven VF inductions (mean 30 +/- 4 per animal) were analyzed. The mean defibrillation threshold could be reduced to 8.0 +/- 3.2 joules with biphasic shocks from 12.9 +/- 5.1 joules obtained for monophasic shocks using a dual electrode system (p less than 0.004). Mean shock leading voltage was correspondingly reduced to 488 +/- 100 V from 691 +/- 154 V (p less than 0.0006).(ABSTRACT TRUNCATED AT 250 WORDS)

The ventricular depolarization gradient: effects of exercise, pacing rate, epinephrine, and intrinsic heart rate control on the right ventricular evoked response.

A new pacing technique is described that permits high fidelity recording of the paced ventricular evoked response, including cardiac depolarization. Integration of the paced R wave yields the ventricular depolarization gradient (GD), which is dependent on activation sequence and the spatial dispersion of activation times. GD was studied in 27 dogs to determine the effects of treadmill exercise at fixed rate pacing (n = 10), elevation of heart rate in the absence of stress (n = 20), epinephrine at fixed rate (n = 6), and exercise in the presence of normal chronotrophic response (n = 7). Low level exercise (1 mph, 2 min, 15 degrees) at a fixed heart rate produced significant (P less than 0.0005) decreases in GD that averaged -10.8 +/- 4.0% (mean +/- SD). The rate of change in GD was faster at the onset of exercise than at its cessation (P less than 0.0005). Artificial elevation of heart rate at rest produced significant (P less than 0.0005) increases in GD; mean sensitivity of GD to rate was 0.27 +/- 0.12%/beats/min. Intravenous injection of epinephrine produced significant (P less than 0.001) decreases in GD at two dosage levels (2.5 and 5.0 micrograms/kg) when evaluated at two baseline pacing rates (150 and 190 beats/min); mean changes in GD were -20.64 +/- 0.53% (2.5 micrograms/kg at 150 beats/min), -25.19 +/- 4.20% (5.0 micrograms/kg at 150 beats/min), -14.18 +/- 5.19% (2.5 micrograms/kg at 190 beats/min), and -24.22 +/- 4.94% (5.0 micrograms/kg at 190 beats/min). Sensitivity of GD to epinephrine was dose-dependent (P less than 0.01) at each baseline rate, but was independent (P greater than 0.05) of the rate itself. In the presence of a normal chronotropic response, GD remained unchanged (P greater than 0.5) during exercise in spite of significant elevation in heart rate (105.0 to 167.1 beats/min, P less than 0.001). These data suggest the presence of an intrinsic negative-feedback control mechanism that maintains GD constant in the healthy heart during homeostatic disturbance. Applications in closed-loop rate adaptive pacing are described.

Psoriasis treatment at the Dead Sea: a natural selective ultraviolet phototherapy.

A naturally filtered ultraviolet spectrum of sunlight along with other natural factors are utilized in the management of psoriasis at the Dead Sea area in Israel. In 110 patients with psoriasis, 85.5% achieved complete clearing or excellent improvement. These results compare favorably with other therapeutic regimens used today in the treatment of psoriasis. Since systemic medications are avoided, the potential risks may be considerably lessened. Therefore, this therapeutic modality may be considered in the management spectrum of psoriasis.