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C C Sweeley

Publications and source records attributed to C C Sweeley.

At least 91 records · Page 5Linked to original sources
PubMed1976

The free-falling drop detector--a nover fluorescence detector for high-performance liquid chromatography.

A novel fluorescence detector for high-performance liquid chromatography has been designed to minimize the instrumental limitations of conventional flow-through, fluorometers. This unit contributes less than 5 mul to the "dead volume" of the chromatographic system. Sensitivity comparable to that of existing flow-through fluorometers has been attained without optimizing instrumental parameters. Performance of the unit has been evaluated with reference samples containing saccharides typical of glycosphingolipids. Future improvements are discussed.

Carbohydrates↗
PubMed1975

Identification of p-hydroxybenzaldehyde as the ligand in the green form of old yellow enzyme.

We have previously reported the isolation of old yellow enzyme complexed with a ligand of low molecular weight which imparts a distinctive charge-transfer absorption to the enzyme, making it green in color (Matthews, R. G., and Massey, V. (1969) J. Biol. Chem. 244, 1779-1789). This ligand has now been identified as p-hydroxybenzaldehyde by removal from the enzyme and characterization of its optical spectrum and subsequent mass spectral analysis. Similar compounds which are also bound to old yellow enzyme have been isolated from yeast extract and identified. These compounds give rise to complexes with old yellow enzyme which are characterized by broad long wavelength absorption bands, and they lead to inhibition of the NADPH-O2 oxidoreductase activity catalyzed by old yellow enzyme.

Benzaldehydes↗
PubMed1975

Metabolism of neutral glycosphingolipids in plasma of a normal human and a patient with Fabry's disease.

[6-2H2]Glucose was used as a tracer for a comparative study on the metabolism of the neutral glycosylceramides in plasma of a control subject and a patient with Fabry's disease. The incorporation of the tracer into the glucosyl and galactosyl moieties of the glycosphingolipids was measured by gas chromatography-mass spectrometry of the tetra-0-acetyl methyl glycoside derivatives. Experiments on the precision and accuracy for measurements of [6,6-2H2]hexose in a sample demonstrated that incorporation of 0.2% or more of [6,6-2H2]glucose could be detected with a 95% confidence limit of +/-0.16%. The labeled substrate (35g) was infused into each subject with a 5-g priming dose and the remainder administered at a constant rate of 3 g/hour over a 10-hour period. During the infusion, the plasma glucose of each subject attained a concentration of about 30% [6,6-2H2]glucose which diminished rapidly after the administration of substrate was complete. A concentration of 0.8% [6,6-2H2]glucose was observed in glucosylceramide (GL-la) from plasma of both subjects between 48 and 72 hours after the infusion began. The label disappeared from this lipid at a logarithmic rate and 0.2% or less of the molecules were labeled 9 days after the experiment began. In contrast to the results with GL-la, the maximum incorporation of [6,6-2H2]hexose into lactosylceramide (galactosyl-(beta1 leads to 4)-glucosylceramide) was 2-fold higher in the Fabry patient (1.6%) than in the control (0.8%). The trihexosylceramide (galactosyl-(alpha1 leads to 4)-galactosyl-(beta1 leads to 4)-glucosylceramide, GL-3a) from plasma of the control reached a maximum of 0.4% [6,6-2H2]hexose in both the glucosyl and galactosyl moieties whereas the GL-3a from the Fabry patient was not significantly labeled. The maximal labeling of the GL-4a fraction (N-acetyl-galactosaminyl-galactosyl-galactosyl-glucosylceramide) was slightly depressed in the Fabry patient (0.4%) as compared to the control (0.7%). Turnover times for the glycosphingolipids of plasma were calculated to be from 4 to 8 days and the turnover rates were from 1 to 6 mumol/day.

Adult↗
PubMed1975

Glycosphingolipid glycosyl hydrolases and glycosidases of synchronized human KB cells.

KB cells were synchronized by a double thymidine block procedure. An investigation was made of the activities of alpha-L-fucosidase (EC 3.2.1.51), alpha-D-galactosidase (EC 3.2.1.22), beta-D-galactosidase (ec 3.2.1.23), alpha-D-glucosidase (EC 3.2.1.20), beta-D-glucosidase (EC 3.2.1.21), alpha-D-mannosidase (EC 3.2.1.24), beta-D-N-acetylgalactosaminidase (EC 3.2.1.53), and beta-D-N-acetylglucosaminidase (EC 3.2.1.52) from synchronized cultures, using appropriate artificial substrates. Ceramide glucosidase (EC 3.2.1.45) and ceramide trihexosidase levels (EC 3.2.1.47) were also investigated at various stages in the cell cycle, using appropriate glycosphingolipid substrates. Whereas each of these enzymes exhibited some activity throughout the cell cycle, peak activity (2- to 6-fold increase) occurred late in the S phase. Two molecular forms of ceramide glucosidase (optimal activity at pH 4.0 and pH 6.0) and two forms of ceramide trihexosidase (pH 4.0 and pH 7.5) were identified. Peak levels of the forms that preferred the relatively acid pH occurred earlier in the S phase of the cell cycle than those of the forms that were more active at the higher pH. The possibility that the forms with optimal activity at pH 4 are precursors of those with optimal activity at pH 6 to 7.5 is discussed. Precipitation of beta-galactosidase of synchronized KB cells with specific antibody revealed that changes in the activity of this enzyme during the cell cycle were the result of fluctuations in the amount of the enzyme.

Acetylgalactosamine↗
PubMed1975

Glycosphingolipids of human KB cells grown in monolayer, suspension, and synchronized cultures.

Studies have been carried out on the glycosphingolipids of human KB cells grown in monolayer and suspension culture, and by synchronization of the latter with a double thymidine (2mM) block. Glycosphingolipids were identified tentatively by thin layer chromatography, gas-liquid chromatography, and combined gas-liquid chromatography and mass spectrometry. The predominant gangliosides in the these cells were AcNeu-Gal-Glc-Cer and AcNeu-Gal-GalNAc-Gal-(AcNeu). Glc-Cer. Theprincipal neutral glycosphingolipids were Glc-Cer, Gal-Glc-Cer, Gal-Gal-Glc-Cer, and GalNAc-Gal-Gal-Glc-Cer. Incubation of KB cells (grown in monolayer and subsequently in suspension culture) for 48 hours with D-[1-14Clgalactose resulted in appreciable incorporation of radioactivity into all of the principal glycosphingolipids of these cells. These experiments confirmed that KB cells are capable of synthesizing their constituent glycosphingolipids. KB cells grown in suspension culture showed A 2- to 3-fold increase inthe concentration of Glc-Cer, Gal-Glc-Cer, GalNAc-Gal-Gal-Glc-Cer, and AcNeu-Gal1NAc-Gal-Gal-Glc-Cer, and AcNeu-Gal-Ga1NAcGal-(AcNeu)-Glc-Cer. Thus, the occurrence of tissue culture-dependent changes in the level of glycosphingolipids is demonstrated. Perhaps messages governing the synthesis of glycosphingolipids are translated earlier in thecell cycle under certain conditions of growth and are affected by cell-cell contact and cell adhesion.

Carbon Radioisotopes↗
PubMed1975

beta-Hydroxy fatty acid production during fatty acid oxidation by heart mitochondria.

The effect of various incubation conditions on the production of beta-hydroxylaurate, -myristate, and -palmitate by isolated rabbit heart mitochondria oxidizing palmityl carnitine was studied. A gas chromatographic-mass spectrometric method was developed to identify and measure submicrogram quantities of methyl esters of these beta-hydroxy fatty acids (FA). Alpha-Deuterated esters of beta-hydroxy-FA served as internal standards. The total amount of the three beta-hydroxy-FA in fresh mitochondria was 0.045 mug/mg of protein. Malate, ATP, rotenone, and 1-carnitine together effected an NADH:NAD ratio of 8 and the accumulation of 0.896 mug of beta-hydroxylpalmitate. Omission of carnitine decreased the beta-hydroxy-FA by 65 percent. Omission of palmityl carnitine resulted in no beta-hydroxy-FA. Without rotenone the NADH:NAD ratio was 0.5 and there accumulated only 0.085 mug of beta-hydroxy-FA/mg of protein/10 min. Succinate, in place of malate, effected an NADH:NAD ratio greater than 10 but only 0.465 mug of beta-hydroxy-FA/mg of protein/10 min. We conclude that elevated mitochondrial NADH:NAD ratios facilitate beta-hydroxy-FA accumulation by slowing beta-hydroxyacyl-CoA oxidation. Cardiac hypoxia may prompt beta-hydroxy-FA accumulation and/or release.

Animals↗
PubMed1975

Fatty acid oxidation by ischemic myocardium.

Ischemia markedly depresses fatty acid oxidation and increases fatty acyl-CoA and fatty acylcarnitine levels in the isolated heart during palmitate oxidation. Evidence suggests that the major defect is impaired beta-oxidation due to decreased electron transport rather than to diminished fatty acyl uptake, activation, or intramitochondrial transfer. Important metabolic effects may include decreased mitochondrial adenine nucleotide translocation and altered carnitine-palmity-l-CoA transferase activity.

Animals↗