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Biomedical subjects

R L Hall

Publications and source records attributed to R L Hall.

At least 91 records · Page 5Linked to original sources
PubMed1977

Amoeboid movement as a correlated walk.

The movement of slime-mold amoebae under isotropic conditions in two dimensions is represented as a Correlated Walk with straight steps of variable length. The steps are correlated via the angle theta turned through from step to step. The hypotheses and predictions of the model compare favourably with experimental data for Dictyostelium discoideum amoebae.

Dictyostelium↗
PubMed1977

3-O-methyl sugars as constituents of glycoproteins. Identification of 3-O-methylgalactose and 3-O-methylmannose in pulmonate gastropod haemocyanins.

In addition to the already knownonosaccharides fucose, xylose, mannose, galactose, glucose, N-acetylgalactosamine and N-acetylglucosamine, the carbohydrate part of the haemocyanin from Helix pomatia (Roman snail) contains 3-O-methylgalactose, and that from Lymnaea stagnalis (a freshwater snail) 3-O-methylgalactose and 3-O-methylmannose. The 3-O-methyl sugars were identified by g.l.c.-mas spectrometry of the corresponding trimethylsilyl methyl glycosides and the alditol acetates, and by co-chromatography with the synthetic reference substances.

Animals↗
PubMed1976

Gallium-67 scintigraphy for the diagnosis and localization of perinephric abscesses.

Four patients with suspected perinephric abscess were evaluated by gallium-67 scintigraphy. Gallium-67 scintigraphs proved instrumental in correctly diagnosing and localizing 4 left perinephric abscesses. Roentgenographic examinations were negative in 2 cases. Gallium-67 scintigraphy can be a useful non-invasive technique to evaluate patients with suspected perinephric abscess.

Abscess↗
PubMed1975

Reduced nicotinamide adenine dinucleotide-nitrate reductase of Chlorella vulgaris. Purification, prosthetic groups, and molecular properties.

NADH:nitrate reductase (EC 1.6.6.1) from Chlorella vulgaris has been purified 640-fold with an over-all yield of 26% by a combination of protamine sulfate fractionation, ammonium sulfate fractionation, gel chromatography, density gradient centrifugation, and DEAE-chromatography. The purified enzyme is stable for more than 2 months when stored at minus 20 degrees in phosphate buffer (pH 6.9) containing 40% (v/v) glycerol. After the initial steps of the purification, a constant ratio of NADH:nitrate reductase activity to NADH:cytochrome c reductase and reduced methyl viologen:nitrate reductase activities was observed. One band of protein was detected after polyacrylamide gel electrophoresis of the purified enzyme. This band also gave a positive stain for heme, NADH dehydrogenase, and reduced methyl viologen:nitrate reductase. One band, corresponding to a molecular weight of 100, 000, was detected after sodium dodecyl sulfate polyacrylamide gel electrophoresis. The enzyme contains FAD, heme, and molybdenum in a 1:1:0.8 ratio. One "cyanide binding site" per molybdenum was found. No non-heme-iron or labile sulfide was detected. From a dry weight determination of the purified enzyme, a minimal molecular weight of 152, 000 per molecule of heme or FAD was calculated. An s20, w of 9.7 S for nitrate reductase was found by the use of sucrose density gradient centrifugation and a Stokes radius of 89 A was estimated by gel filtration techniques. From these values, and the assumption that the partial specific volume is 0.725 cc/g, a molecular weight of 356, 000 was estimated for the native enzyme. These data suggest that the native enzyme contains a minimum of 2 molecules each of FAD, heme, and molybdenum and is composed of at least three subunits.

Binding Sites↗
PubMed1972

The question of the primary electron acceptor in bacterial photosynthesis.

An electrophoretic purification of Rhodospirillum rubrum photoreceptor subunits prepared by alkaline urea-detergent disruption is described. Completely active photoreceptor subunits with less than 0.30 eq of iron (or any other transition metal) per phototrap can routinely be prepared. A new photoproduced electron paramagnetic resonance (EPR) signal has been detected in these preparations; it was shown to be due to a photoreduced species. It has a g-value of 2.0050 +/- 0.0003, a peak-peak width of 7.0 +/- 0.3 G, and a nearly Gaussian shape. The response of the new signal to microwave power is different from that of the EPR signal of the photoproduced primary electron donor of chromatophores. Quantum yield measurements of spin production show that the new signal is very efficiently formed (varphi = 0.6) simultaneously with the electron donor radical. No hyperfine structure (down to 0.1 G modulation amplitude) was observed in the new signal, either at room temperature or at the temperature of liquid nitrogen. The possible identity of this molecule is discussed.

Electron Spin Resonance Spectroscopy↗