Biomedical subjects
Publications and source records attributed to R L Bowman.
Nuclear magnetic resonance principles have been applied to measure biological blood flow. The method is non-intrusive and can be used to measure peripheral blood flow or blood flow from various organs. The mechanisms of NMR are described and studies of blood flow in limbs and the head are discussed.
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A flow-through centrifuge without rotating seals enables the use of polymer phase systems for chromatographic separation of macromolecules. The capability of the technique is demonstrated on partition of polynucleotides.
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We have developed an optical scanning instrument which may become a valuable aid in a variety of cell studies. Cell multiplication can be readily monitored with the instrument. By varying the chemical environment in which the cells are tested, questions of research and clinical interest may be quickly and conveniently answered. It appears possible to investigate the chemotherapeutic value of experimental agents, and to scan the sensitivity of a given population of neoplastic cells to a variety of chemotherapeutic agents at several concentrations. The optical scanning system may also be used to investigate certain metabolic pathways of cells in tissue culture, to determine drug resistance, and to assess the effects of medium composition on cell growth. Our studies of BrdU resistance in mouse lymphoma cells were done primarily to demonstrate the potential of this optical scanning method, and we do not intend to continue the cytokinetic studies at present. We trust that others will be stimulated to investigate further applications of this instrumental approach to problems in cell biology.
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We have developed a new method of countercurrent chromatography which employs a vertical helical tube in the centrifugal field. The helical tube is arranged so that it does not rotate as it revolves, thus eliminating the need for rotating seals. When the gyrating tube is filled with either phase and the other phase is introduced into the tube in the proper direction, an equilibrium state results in which the two phases are split into multiple alternating segments within the coil. Each phase oscillates to and fro with the rotation as the moving phase is steadily eluted out through the other end of the tube. Consequently, solutes introduced into the tube are subjected to a rapid partition process, resulting in an efficient chromatographic separation without the complications arising from solid supports. The method is illustrated by the microanalytical separation of dinitrophenyl amino acids and can be used on a preparative scale.
A new form of countercurrent chromatography, named droplet counter-current chromatography, has been developed. This all-liquid separation technique is based on the partitioning of solute between a steady stream of droplets of moving phase and a column of surrounding stationary liquid phase. Milligram quantities of dinitrophenyl (DNP) amino acids were separated with an efficiency comparable to that of gas chromatography.
The liquid-liquid partition chromatographic system reported here involves a long helix of narrow-bore tubing. When the coiled tube is filled with one phase of a two-phase system and fed with the other phase, phase-interchange takes place in each turn of the coil, leaving a segment of the former phase as the stationary phase. Consequently, solutes present in either phase are subjected to a multistep partition process. The column efficiency, estimated on a separation of dinitrophenyl amino acids, is comparable to that of gas chromatography.
A premature lamb fetus was totally sustained by extracorporeal perfusion with the use of a silicone-membrane blood oxygenator and parenteral nutritional support. The fetus remained in a metabolically stable state lasting several days.
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Growing microcolonies of bacteria can be detected by their light-scattering property. We have described a system in which growing bacteria in glass capillaries filled with nutrient agar are counted as the capillaries move through a narrow beam of light. Increased counts after incubation indicate the presence of viable organisms in the original sample; the equipment can detect colonies when they grow to a diameter of 8 microm. Aerobic, anaerobic, and facultative organisms can grow in the capillary environment. The sensitivities of several organisms to antibiotics were determined by adding antibiotics to the agar before the capillaries were filled.
A mixer made from a bundle of glass tubules can mix two solutions within 30 microseconds, with a total-solution flow rate of 1.33 milliliters per second. One solution passes through the interstices of the bundle; the other moves through the lumens of the tubes.
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