Biomedical subjects
Publications and source records attributed to S P Mathur.
A simple, cost-effective, and accurate technique to measure the whole-body-averaged specific absorption rate (SAR) in Sprague-Dawley rat carcasses by a single-gradient-layer calorimeter is described. The results of SAR determinations showed a highly linear relation between the average power density of the incident field (1.25 GHz) and the normalized heat loading of the carcasses.
A hypothesis of microwave-induced circulatory under perfusion was tested in ketamine anesthetized rats whose heart rate, mean arterial pressure, pulse pressure, respiration rate, and body temperatures were monitored continuously. Fifty-eight ventral head and neck exposures in a waveguide consisted of sham-exposure and exposure to continuous wave (CW) and pulsed 1.25 GHz microwaves for 5 min. The 0.5 Hz (10 microseconds, 2 W average) and 16 Hz (1 microsecond, 6.4 W average) pulse-modulated microwaves were delivered at 400 kW peak power. The CW microwaves were 2 and 6.4 W. The average specific absorption rate was 4.75 W/kg per watt transmitted in the brain and 17.15 W/kg per watt transmitted in the neck. Respiration rate and mean arterial pressure were not altered. Changes in heart rate and pulse pressure were observed in rats exposed to higher power (16 Hz pulses and 6.4 W CW) but not to the lower average power microwaves (0.5 Hz pulses and 2 W CW). Depression of pulse pressure, an indication of a decrease in stroke volume, and increased (tachycardia) or decreased (bradycardia) heart rate were noted in presence of whole-body hyperthermia. The cardiac output of those animals exposed to higher average power microwaves was considered to be below normal as hypothesized. Decreased cardiac output and normal mean arterial pressure resulted in an increase in the total peripheral resistance which was contrary to the anticipated thermal response of animals.
A total of 138 eye specimens were processed for aerobic and anaerobic cultures. Clinical data were obtained from 50 patients with unilateral ophthalmic infection. Cultures from the uninfected eye of 38 of these 50 patients were also processed for comparison. In addition, 50 cultures were obtained from one or both eyes of 30 healthy controls who had no eye infection. Anaerobes and aerobes were isolated from infected eyes of 6 (12%) and 37 (74%) patients respectively. No growth was observed in infected eye of 8 (16%) patients. A mixture of aerobes and anaerobes were recovered only in 2 cases. Of the total 47 aerobic isolates from infected eye specimens, Staphylococcus aureus (11), coagulase negative staphylococci (12) and Streptococcus pneumoniae (9) were predominant isolates. Six anaerobes isolates included Gram positive nonsporing anaerobic bacilli (4 including Propionibacterium acne) as predominant isolates. Clostridium perfringens was isolated from a case of post operative endoophthalmitis. From the uninfected eye of same patients though the number and types of aerobic bacteria were similar, none grew any anaerobes. Aerobic and anaerobic bacteria were isolated in 70 and 6 per cent of eye swabs respectively from the healthy controls.
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Samples from three cultivated soils and one from a roadside, all in Ontario, were found to contain less than 1 to 68 ppb of 1,2-Benzanthracene (BA). Two plots subjected to stubble (residue of wheat crop) burning annually for 15 years did not contain significant amounts of BA, although polyaromatic hydrocarbons, including BA, result from pyrolysis of most organic matter.
A modified technique of sutureless Fasanella-Servat Operation (F.S.O.) using special curved haemostat for the correction of mild to moderate acquired ptosis with good Levator Palpebrae Superioris (L.P.S.) action (12 m.m.) was performed in a large series of 50 eyes. Excellent correction was achieved in 94.6% eyes with mild ptosis & 61.6% eyes with moderate ptosis. No operative and post operative complications were observed. The technique was found to be very safe, quick and effective.