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Biomedical subjects

R C Murphy

Publications and source records attributed to R C Murphy.

At least 199 records · Page 11Linked to original sources
PubMed1983

Studies on the physical state of water in living cells and model systems. II. NMR relaxation times of water protons in aqueous solutions of gelatin and oxygen-containing polymers which reduce the solvency of water for NA+, sugars, and free amino acids.

This communication reports our study of the NMR relaxation times, T1 and T2 of water protons in aqueous solutions of bovine serum albumin, gelatin, polyvinylpyrrolidone, poly(ethylene oxide), and polyvinylmethylether over a wide concentration range. In contrast to solutions of gelatin and bovine serum albumin, the T1/T2 ratio of the three synthetic polymers are close to unity over the entire range studied. When combined with earlier-reported data of water made "non-solvent" to Na salts, the present data provided the basis for calculating the T1 and T2 as well as the rotational correlation time tau c of the "non-solvent" water. It was shown that only a modest increase by a factor of about 3 of tau c is enough to produce water that is "non-solvent" for Na citrate and sulfate. The new data reconciles NMR data of living cells with the theory of the cell water given in the association-induction hypothesis. The variability of tau c of "non-solvent" water also offers explanations of apparently conflicting conclusions on the physical state of cell water from dielectric measurements.

Amino Acids↗
PubMed1982

Rapid extraction of leukotrienes from biologic fluids and quantitation by high-performance liquid chromatography.

Previous methods for the recovery and quantitation of leukotrienes have involved tedious extraction procedures, and high-performance liquid chromatographic (HPLC) techniques with significant limitations. We have designed a method to extract leukotrienes from biologic fluids using commercially available silica mini-columns requiring minimal preparation. Sample clarification is followed by a sensitive and reproducible HPLC technique which separates and quantifies the leukotrienes LTC4, LTD4, LTB4 (and at least three of their isomers). The entire procedure requires less than one hour per sample.

Cell Line↗
PubMed1982

Nonimmunological production of leukotrienes induced by platelet-activating factor.

Platelet-activating factor caused rapid pulmonary vasoconstriction and edema in isolated lungs perfused with albumin-free salt solution devoid of formed blood elements. These effects may be due in part to the action of leukotrienes D4 and C4, which were identified by bioassay and high-pressure liquid chromatography in the lung effluent after stimulation by platelet-activating factor. These findings help illuminate some of the deleterious effects that platelet-activating factor elicits in anaphylactic reactions and possibly in other forms of lung injury.

Animals↗
PubMed1982

Leukotriene C4 and D4 formation by particulate enzymes.

The homogenate of rat basophilic leukemia cells, when incubated with arachidonic acid, glutathione, and calcium, formed 3 isomers of 5,12-dihydroxyeicosatetraenoic acid and 2 isomers of 5,6-dihydroxyeicosatetraenoic acid, as well as leukotriene (LT) C4 and D4. The products were identified by high pressure liquid chromatography, ultraviolet spectral analysis, co-migration with standards, bioassay, and gas chromatography-mass spectrometry. The enzymes responsible for the formation of LTC4 and LTD4 from LTA4 were found in the 10,000 x g pellet and, therefore, appear to be particulate. The possibility that these enzymes are bound to the cell membrane suggest that the formation of these leukotrienes might be important in the basophil and mast cells release reaction.

Animals↗
PubMed1982

Leukotriene generation by eosinophils.

Horse eosinophils purified to greater than 98% generated slow reacting substance (SRS) when incubated with the calcium ionophore A23187. On a per cell basis, eosinophils generated four to five times the SRS produced by similarly treated horse neutrophils. Eosinophil SRS production was inhibited by 5,8,11,14-eicosatetraynoic acid and augmented by indomethacin and arachidonic acid, suggesting that it was a product(s) of the lipoxygenase pathway of arachidonic acid metabolism. Compounds with SRS activity were purified by high-pressure liquid chromatography (HPLC) and identified by ultraviolet spectra, spectral shift on treatment with lipoxygenase, incorporation of [14C]arachidonic acid, gas chromatography-mass spectrometry, and comparison of retention times on HPLC to authentic standards. The eosinophil products characterized were 5-(S), 12-(R)-dihydroxy-6-cis-8, 10-trans-14-cis-eicosatetraenoic acid (leukotriene B4) and its 5-(S), 12-(R)-6-trans and 5-(S), 12-(S)-6-trans isomers, 5-(S)-hydroxy-6-(R)-S-glutathionyl-7,9-trans-11, 14-cis-eicosatetraenoic acid (leukotriene C4) and its 11-trans isomer, and 5-(S)-hydroxy-6-(R)-S-cysteinylglycine-7,9-trans-11,14-cis-eicosatetraenoic acid (leukotriene D4).

Animals↗
PubMed1982

Comparison of biological-derived and synthetic leukotriene C4 by fast atom bombardment mass spectrometry.

The development of the technique of fast atom bombardment mass spectrometry (FAB-MS) has greatly expanded the capability to analyze non-volatile, complex biochemicals. The structure of leukotriene C4, a slow reacting substance of anaphylaxis, has recently been postulated as 6-glutathionyl-5-hydroxy-7,9,11,14-eicosatetraenoic acid. Even though LTC4 has been synthesized, it has not been possible to obtain direct mass spectrometric confirmation of this structure. FAB-MS has indicated that the biological LTC4 had a molecular weight of 625, identical to that of synthetic LTC4. The abundance of cationized species with one and two sodium atoms was the major difference between these leukotrienes which is probably a result of the difference in salt content of the purified molecules.

Mass Spectrometry↗
PubMed1981

Leukotrienes C and D induce aspirin-sensitive bronchoconstriction in the guinea-pig.

Branchoconstriction in the guinea-pig due to leukotrienes C4 and D4 in vivo and in vitro was suppressed by aspirin. Since contracting effects of putative mediators of bronchial asthma should be refractory to inhibition of cyclooxygenase, our results indicate that release of leukotrienes in the guinea-pig does not alone account for anaphylactic bronchoconstriction.

Airway Resistance↗