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Biomedical subjects

T S Sandhu

Publications and source records attributed to T S Sandhu.

At least 19 recordsLinked to original sources
PubMed1986

Measurement of blood flow using temperature decay: effect of thermal conduction.

Within the framework of the bioheat equation, we studied the effect of conduction on the thermal washout curve for a model tissue configuration subjected to a thermal perturbation such as hyperthermia treatment. In particular, we studied the implications of the assumption made by many investigators to neglect the effect of thermal conduction while analyzing the temperature decay curve for measuring blood perfusion. The present analysis suggests that during the localized hyperthermia treatments, this assumption can lead to inaccurate values for the blood perfusion parameter. This is particularly so under non-steady state conditions when the temperature distribution is changing. In addition to the value of blood flow, the shape of the temperature decay curve depends on the temperature distribution at the start of temperature decay.

Blood Flow Velocity↗
PubMed1985

Practical thermal dosimetry.

A relatively simple means of thermal dose documentation is presented. It has the advantage of greatly condensing the vast amount of data collected during a course of hyperthermia treatments. The formulation incorporates both temporal and spatial temperature transients and is applicable when comparing hyperthermia devices and in quality control for prospective hyperthermia treatment protocols.

Humans↗
PubMed1985

The frequency of salmonellae on duck eggs.

Total plate counts on washed duck eggs from a breeder farm on Long Island were less than 30/shell during the winter (January to February) of 1982. Clean unwashed eggs had counts less than 9 X 10(1)/shell, whereas dirty unwashed eggs had counts as high as 9 X 10(5)/shell. Our results showed that washing with a chlorine sanitizer (under commercial conditions) was highly effective in reducing surface bacterial counts on egg shells. Prolonged storage reduced bacterial counts on clean eggs, but it did not significantly affect loads on dirty eggs. No salmonellae could be detected on shells or in the magma of all eggs examined. In a second trial (March 1982) bacterial loads on washed and clean duck eggs from six different breeder farms were low, ranging from too few to count to 10(2)/shell. A higher proportion of dirty eggs were heavily contaminated with counts ranging from 10(5) to 10(6)/shell, but no salmonellae were detected either on shells or in magma. In the third trial (May 1982) bacterial determinations on eggs from breeder ducks that were not confined followed the pattern of the second trial. However, in this trial Salmonella enteritidis was detected on dirty egg shells in four of six farms. In a fourth trial (May 1983), bacterial loads on washed and nest-clean eggs from the same breeder farms (not confined) ranged between 10(2) to 10(3)/shell and 10(2) to 10(4)/shell, respectively. S. enteritidis and S. badar were recovered from washed, nest clean, and dirty eggs in two of six farms. We conclude that proper egg washing and confinement of duck breeders should minimize the problem of salmonellosis in ducklings.

Animals↗
PubMed1982

Results of a phase I/II clinical trial of fractionated hyperthermia in combination with low dose ionizing radiation.

This paper addresses, in part, the current status of hyperthermia as a new clinical modality and reports the results of a large, prospective clinical trial employing microwave hyperthermia in combination with low doses of ionizing radiation. In the protocol employed, each treated area received 8 hyperthermia treatments of 1.5 hour combined with 1600 rad over a total period of 5 weeks. Patients were heated with microwaves of 915 or 300 MHz employing external applicators or internal intracavitary antennas. The results of this fractionation scheme are encouraging since in 121 fields that were treated completely according to protocol and were available for follow-up for at least 2 months, complete responses were observed in 65% of all cases, partial response in 30% and no response in only 5%. It is also important to note that toxicity was minimal throughout the study.

Clinical Trials as Topic↗
PubMed1980

Effects of hyperthermia on normal and tumor microenvironment.

The effects of hyperthermia on pH, local blood flow (LBF) and tissue oxygen tension (TpO2) in several normal and tumor tissues were studied. It was found that TpO2, local blood flow and pH are inhomogeneous in tumor tissue. TpO2 is very low in certain areas which also seem deprived of blood flow and are at very low pH. Hyperthermia has a dual effect: at temperatures below 41 degrees C, it increases blood flow and TpO2 while above 41 degrees C, it causes a collapse in blood flow, lower TpO2 and a shift of the tissue pH towards acidosis from the already low pH values found in tumors.

Adenocarcinoma↗
PubMed1980

Effect of chemotherapeutic agents on Pasteurella anatipestifer infection in White Pekin ducklings.

In a series of experiments, various chemotherapeutic agents administered in feed were evaluated for their efficacy against experimental Pasteurella anatipestifer (PA) infection in White Pekin ducklings. The feeding of medicated diets was started 3 days prior to challenge and continued throughout each experiment. Novobiocin and lincomycin, when fed at adequate concentrations, were the most effective medicaments tested. Mortality in treated groups was 0-18% compared with 45-92% mortality in controls. Sulfadimethoxine-ormetoprim, sulfaquinoxaline, and lincomycin-spectinomycin were moderately effective. Drugs that were not effective included chlortetracycline, tylosin-sulfamethazine, fosfomycin, furazolidone, nihydrazone, penicillin, bacitracin, and erythromycin. Six antibiotics were tested parenterally against experimental PA infection in another series of experiments. A single dose of an antibiotic was injected subcutaneously 5 to 6 hr after infection except in one experiment in which treatment was delayed until 24 hr after infection. When given 5 to 6 hr after infection, lincomycin-spectinomycin, penicillin-streptomycin, penicillin, oxytetracycline, and spectinomycin significantly reduced mortality. Gentamicin tested under the same conditions was ineffective. Drugs injected 24 hr after infection were not effective.

Animals↗
PubMed1977

Production and characterization of Moraxella bovis hemolysin.

Moraxella bovis hemolysin was produced in trypticase soy broth and maximum hemolytic activity of the culture was observed during the logarithmic phase of growth. The hemolysin was filterable through a 0.22-micrometer (APD) membrane filter, heat labile, and destroyed by treatment with formalin or trypsin. There was no difference in the amount of hemolysin production by rough or smooth colony types of an isolate, although differences were observed between 2 different isolates. Partial requirement of a sulfhydryl group and divalent cations were suggestive of an enzymatic nature of M bovis hemolysin.

Calcium↗
PubMed1976

The structlre of pili (fimbriae) of Moraxella bovis.

Cells from rough and smooth colonies of Moraxella bovis were examined by electron microscopy utilizing both shadowing and thin sectioning techniques. Pili were found on the surfaces of cells from rough but not smooth colonies. Pili had a peritrichoud distribution and appeared as delicate (6.5-8.5 nm in diameter), elongated unbranched filaments. When bacteria were sectioned pili did not contain central pores and appeared to originate from opacities on the surface of the cell wall.

Animals↗
PubMed1976

Extracellular antigens of Moraxella bovis.

The extracellular antigens of 2 isolates of Moraxella bovis were isolated by ammonium sulfate precipitation of cell-free culture filtrate, purified by filtration and differentiated by immunodiffusion and immunoelectrophoretic techniques. The extracellular filtrate from rough types had 2 specific extracellular antigens in addition to those in the culture filtrate of smooth-type cells of the same isolate. The extracellular antigens produced by smooth-type cells were identical in all isolates of Moraxella bovis. The serotype-specific extracellular antigens of 2 isolates were serologically identical but were different from those of a 3rd isolate. The possibility of serotyping M bovis isolates, on the basis of their extracellular rough-type antigens, was suggested. Although both serotype-specific antigens were destroyed by trypsin treatment, 1 antigen was also heat-labile and partially destroyed by formalin treatment.

Antigens, Bacterial↗
PubMed1972

Evaluation of a macroscopic plate test and an indirect immunofluorescence test to detect leptospiral antibodies in bovine serum.

A macroscopic plate test was found to be reliable and convenient for detection of Leptospira serotype pomona antibodies in bovine sera. However, the procedure was unreliable for detecting L. serotype canicola antibodies because of false positive reactions. An indirect immunofluorescence test and the microscopic agglutination test provided comparable results and they effectively detected serotype pomona antibodies in bovine sera.

Agglutination Tests↗