Biomedical subjects
R Blumhardt
Publications and source records attributed to R Blumhardt.
Tests of vitamin B 12 absorption.
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Plasmodium ovale malaria acquired in Viet-Nam.
Four cases of Plasmodium ovale malaria are reported among US servicemen stationed in Viet-Nam between January 1966 and March 1969. Taken together with other cases cited by the authors, these provide strong evidence of the existence (sometimes disputed) of this Plasmodium in continental South-East Asia.None of the men had served in any other area of endemic malaria and their travel and medical histories suggest that all 4 infections were acquired by mosquito transmission. They constitute only 0.066% of the 6036 malaria cases reported among servicemen returning from Viet-Nam during this period and represent only 0.11% of the blood films from 3686 individuals examined at the US National Malaria Repository during the same period.Serological testing for malaria antibodies with the indirect fluorescent technique corroborated the diagnosis of P. ovale in 1 case. Speciation was not possible in the other 3 cases since titres to P. vivax and P. ovale antigens were identical. Only 1 of the patients reported previous experience with vivax malaria.Most of the parasites seen in thin blood films were developing trophozoites and immature schizonts; ring forms and gametocytes were rare; mature schizonts were not found. The morphology of the parasites was typical of P. ovale, with more than 50% of the infected cells showing fimbriations, an oval shape or both.
Depression of poison ivy skin tests by measles vaccine.
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Distance and depth measurements of radioactive objects utilizing rotating slant-hole collimators.
It is desirable to have an accurate method to determine the depth of various organs which are commonly imaged in nuclear medicine. The method presented here utilizes the geometrical characteristics of the rotating slant-hole collimator to calculate distances and depth. The accuracy of the calculated distance was evaluated for point sources in air separated by 11 cm. The reproducibility of the calculated distance was evaluated as a function of the extent of collimator rotation between observations for angular differences of 45 degrees, 90 degrees, 135 degrees, and 180 degrees. The theory of the method is discussed and the relative error in distance calculation analyzed mathematically as a function of (1) collimator rotation angle error, (2) collimator slant angle error, and (3) position calculation error. Our findings indicate this method to be accurate to within 2% with a reproducibility range of 3%-5% for point sources.
Enhanced drug retention in VX2 tumors by use of degradable starch microspheres.
Twenty-nine rabbits with 12- to 14-day-old VX2 tumors in the hind leg were injected intraarterially with technetium-99m (99mTc) DTPA and various combinations of biodegradable starch microspheres, Spherex (Pharmacia, Sweden), to evaluate the efficacy of the microspheres in enhancing tumor retention of 99mTc DTPA. A gamma camera and nuclear medicine computer were used to generate time activity curves of 99mTc DTPA concentration in the tumors. Blood flow to the tumor and various muscles was also measured at intervals by left ventricular injection of 15 micron radiolabeled plastic microspheres. Ninety minutes following the administration of 99mTc DTPA, specimens from the tumor, plasma and different muscles were counted in a NaI well counter connected to a multichannel analyzer. When biodegradable microspheres mixed with 99mTc DTPA were injected and followed by a slow infusion of plain starch microspheres, the 99mTc DTPA was retained in the tumor at concentrations up to 11 times that seen when 99mTc DTPA alone was injected; the corresponding biological half-time was 13 times longer than control values. Additionally, the degree of drug retention was inversely related to blood flow, with retention increasing as blood flow decreased. The results have possible applications to the use of biodegradable microspheres in the intraarterial delivery of chemotherapeutic agents to solid tumors.