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Biomedical subjects

R H Thomas

Publications and source records attributed to R H Thomas.

At least 73 records · Page 4Linked to original sources
PubMed1983

Response of colony-forming units-spleen to heavy charged particles.

Survival of colony-forming units-spleen (CFU-S) was measured after single doses of photons or heavy charged particles from the BEVALAC. The purposes were to define the radiosensitivity to heavy ions used medically and to evaluate relationships between relative biological effectiveness (RBE) and dose-averaged linear energy transfer (LET infinity). In in vitro irradiation experiments. CFU-S suspensions were exposed to 220 kVp X rays or to 20Ne (372 MeV/micron) or 40Ar (447 MeV/micron) particles in the plateau portion of the Bragg curve. In in vivo irradiation experiments, donor mice from which CFU-S were harvested were exposed to 12C (400 MeV/micron). 20Ne (400 or 670 MeV/micron), or 40Ar (570 MeV/micron) particles in Bragg peaks spread to 4 or 10 cm by spiral ridge filters. Based on RBE at 10 survival, the maximum RBE of 2.1 was observed for 40Ar particles characterized by an LET infinity of approximately 100 keV/micron. Lower RBEs were determined at lower or higher estimated values of LET infinity and ranged from 1.1 for low energy 40Ar particles to 1.5-1.6 for low energy 12C and 20Ne. The responses of CFU-S are compared with responses of other model systems to heavy charged particles and with the reported sensitivity of CFU-S to neutrons of various energies. The maximum RBE reported here, 2.1 for high energy 40Ar particles, is somewhat lower than values reported for fission-spectrum neutrons, and is appreciably lower than values for monoenergetic 0.43-1.8 MeV neutrons. Low energy 12C and 20Ne particles have RBEs in the range of values reported for 14.7 MeV neutrons.

Animals↗
PubMed1979

Portal vein invasion demonstrated by ultrasound.

Two patients evaluated by ultrasound for abdominal masses were found to have thrombus within their central portal veins. Their cases are presented with angiographic correlation. Both are proven cases of hepatocellular carcinoma. The importance of evaluation of the portal vein in patients with liver neoplasms is discussed.

Aged↗
PubMed1978

Persistant corpus luteum cyst of pregnancy: sonographic evaluation of cause of third trimester bleeding.

Corpus luteum cysts are frequently observed in pregnant patients evaluated with diagnostic ultrasound. They are usually regarded as incidental findings because of their limited size and usual pattern of regression by ten weeks. The presence and persistence of larger corpus luteum cysts or other extrauterine masses may complicate pregnancy. A case of a large persistent corpus luteum cyst associated with third trimester bleeding is presented.

Adult↗
PubMed1977

The atrophic postmenopausal uterus.

The size of postmenopausal uterus varies, but after 65 years of age, it routinely appears atrophic. A pelvic mass in this age group should not be assumed to be within the uterus unless a careful search excludes an atrophic uterus. Single sweep longitudinal ultrasound sections are the best method of localizing a small uterus, but sometimes gain settings must be varied to demonstrate the organ.

Aged↗
PubMed1977

The effect of alcohol upon "muscle pull" of mice.

Equipment is described for measuring the pull exerted by mice to escape tail restraint and enter a black box. Alcohol, at doses exceeding about 2.5 g/kg, intraperitoneally, significantly decreased "muscle pull", measured 5-60 min after administration. Fifty per cent depression of muscle pull was obtained with doses of about 3.04, 3.18 and 3.55 g/kg of alcohol, 15, 30 and 60 min after alcohol administration, respectively. Depression of muscle pull correlated with alcohol concentrations in the blood plasma. The data show that muscle pull was decreased in only a few animals with plasma alcohol concentrations of less than about 250 mg%, but was significantly depressed in animals with plasma alcohol concentrations of 350 mg% or more. Although differing from it in some respects, the method described is similar to the tilting-plane method which has been used in studies dealing with the effect of alcohol in rats and mice.

Animals↗