Biomedical subjects
Publications and source records attributed to R Bowman.
The toposcopic catheter is an everting tube that advances within a vessel without moving over the endothelium. It easily passed through simulated tortuous vessels which other catheters could not negotiate and was also successful in the external carotid, vertebral, hepatic, renal and coronary arteries in dogs. The catheter advances to its full length (30 cm) or until wedged in small peripheral arteries.
The mechanism by which gentamicin augments the uptake of p-aminohippurate (PAH) by rat renal cortical slices was investigated. In all experiments, gentamicin was administered as gentamicin sulfate at 100 mg/kg b.wt. per day for 2 days; control rats were injected with saline. The effect of gentamicin on the metabolism of PAH to p-aminobenzoic acid (PABA), acetyl-PABA and acetyl-PAH was studied by high performance liquid chromatography. No metabolites of PAH were detected in renal slices of gentamicin-injected or control rats incubated in medium containing PAH. Efflux of 14C-PAH was measured after incubating renal cortical slices for 2 hours in medium containing 8 X 10(-5) M 14C-PAH. The efflux rate constant was 0.080 +/- 0.003/min in control slices and 0.059 +/- 0.003/min in gentamicin slices, P less than .001. No significant difference in the diffusible pool of PAH was found between the two groups which supports an argument against increased tissue-binding of PAH as the explanation for the augmented uptake of PAH by slices of gentamicin-injected rats. Active PAH transport was assessed in terms of Michaelis-Menten kinetics. Vmax was 0.93 +/- 0.08 micronmol/g/15 min in control slices and 1.37 +/- 0.10 micronmol/g/15 min in gentamicin slices (P less than .005). The apparent reaction rate constant (Km) was not different; Km was 0.25 +/- 0.03 and 0.29 +/- 0.04 mM in control and gentamicin slices, respectively (P less than .4). In contrast to PAH, gentamicin did not alter uptake of N'-methynicotinamide, an organic base; nor did it alter the efflux rate constant or diffusible pool of N'-methylnicotinamide. Increased PAH uptake was still evident when slices of gentamicin-injected rats were incubated in medium without acetate. These studies indicate that gentamicin stimulates active PAH transport and decreases PAH efflux in rat renal cortical slices. Both changes implicate an effect of gentamicin at the antiluminal membrane of proximal tubular cells. The finding of an increase in Vmax without a change in Km raises the possibility that gentamicin increases the amount or availability of carrier protein-mediating PAH transport.
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Because of recent increases in bone marrow transplantation, the lack of available matched sibling donors has become a problem. This study investigated the feasibility of obtaining volunteer bone marrow donors unrelated to the patient. A program was developed to inform potential donors and obtain their consent for listing in a bone marrow donor registry. Sixty-six percent of whole blood or apheresis donors agreed to participate in the program. There were no demographic differences between those who accepted or declined to participate. Religion, experiences with medical practices, and the attitude of the potential donor's spouse were important factors in the decision to participate. A search for donors was initiated for 127 patients. Thirty searches were not completed, primarily because of patient-related problems. A total of 713 HLA-A and -B antigen-identical donors was located for 63 of the 97 (65%) patients. A total of 40 HLA-A, -B, and -DR antigen-identical donors was located for 18 of these 63 patients. Six of these 18 patients then had one or more donors (total, 9) whose lymphocytes did not react in mixed lymphocyte culture. Thus, using the file of 2147 donors, an HLA-identical donor was located for 6 percent of the 97 patients. None of these patients has yet received a transplant; in four cases this was due to patient-related and in two cases donor-related reasons. The cost to establish the donor program averaged $33.46 (1984) per donor for donors already typed for HLA-A and -B antigens. This experience indicated that, given thorough information about bone marrow donation and transplantation, a majority of blood and apheresis donors will volunteer to donate bone marrow, without feeling pressure to do so. A relatively small donor file provided donors for 6 percent of patients. The long-term value of bone marrow transplantation using unrelated donors and the optimum size of the donor file remain to be established.