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Biomedical subjects

F Snyder

Publications and source records attributed to F Snyder.

At least 145 records · Page 8Linked to original sources
PubMed1979

Subcellular site and mechanism of synthesis of disaturated phosphatidylcholine in alveolar type II cell adenomas.

The site of synthesis of 1,2-disaturated-(diacyl)-sn-glycero-3-phosphocholine (Sat2PC) in mouse alveolar type II cell adenomas has been studied by conducting pulse-chase experiments. Isolation of microsomal and lamellar body fractions from adenomas after a 20-min pulse with [methyl-3H]choline demonstrates that Sat2PC first appears in the microsomal fraction, and after a short lag subsequently appears in the lamellar body fraction. The kinetics of labeling of Sat2PC are consistent with the microsomal membranes functioning as the subcellular site of synthesis for this pulmonary surfactant phospholipid. Short term labeling experiments with [9,10-3H]palmitate demonstrate that this fatty acid is incorporated into the sn-2 position of Sat2PC at a faster rate than its incorporation into the sn-1 position. This finding indicates that the synthesis of Sat2PC occurs by a deacylation-reacylation mechanism.

Adenoma↗
PubMed1979

Quantitative chromatographic method for the determination of low levels of nitrilotriacetic and ethylenediaminetetraacetic acids in diethylenetriaminepentaacetic acid.

A quantitative method for determination of low levels (0.05%, w/w) of nitrilotriacetic and ethylenediaminetetraacetic acids in diethylenetriaminepentaacetic acid is described. Palmitic acid is added to the chelator as an internal standard before esterification with methanol containing 2%(v/v)H2SO4. The methyl esters of palmitic, nitrilotriacetic, and ethylenediaminetetraacetic acids are first separated from diethylenetriaminepentaacetate by silicic acid column chromatography and are subsequently quantitated by gas-liquid chromatography. The method is both accurate and reproducible with less than 10% relative error. Thin-layer chromatographic separations of the methyl esters, and quantitation at the 1% level, are also described.

Acetates↗
PubMed1979

Successful separation of depressed, normal, and insomniac subjects by EEG sleep data.

Data from all-night EEG sleep studies were used to distinguish normal subjects, primary depressed patients, and primary insomniac patients. In part 1, we compared 41 normal subjects, 56 depressed patients, and 18 insomniacs. In a univariate comparison with normal subjects, depressed patients showed less total sleep, longer sleep latency, more early morning awake time, more intermittent awake time, less delta sleep, less sleep efficiency, and shorter rapid eye movement (REM) latencies; compared with insomniacs, depressed patients showed greater early morning awake time, shorter REM latency, greater REM index, and greater REM density. Using multivariate discriminant analysis, 82% of the sample were correctly classified by diagnosis: 100% of the normal subjects, 72% of the depressed patients, and 77% of the insomniacs. Eight variables contributed to the multivariate separation of depressed individuals from insomniacs and normals: total sleep time, total recording period, sleep efficiency, sleep latency, early morning awake time, awake time, REM time and REM%. When the discriminant functions were applied to a second group of 18 primary depressed patients, 82% were correctly classified as depressed. These results suggest that primary depressed patients and primary insomniac patients may show relatively characteristic patterns of sleep abnormality.

Adult↗
PubMed1979

Acyl-CoA reductase specificity and synthesis of wax esters in mouse preputial gland tumors.

Long-chain alcohols are synthesized in the mouse preputial gland tumor (ESR-586) by NADPH:acyl-CoA oxidoreductase. In this study, a series of labeled acids was tested as substrates for the oxidoreductase in a cell-free system from the tumor, and the distribution of label into alcohols, waxes, and other products was determined. The system contained the labeled acid, an acyl-CoA-generating system, an NADPH-generating system, and tumor homogenate. The highest rates of alcohol synthesis were obtained with palmitic (16:0), heptadecanoic (17:0), stearic (18:0), myristic (14:0), elaidic (18:1 trans), and linoleic (18:2) acids, which yielded, respectively, 151, 124, 102, 76, 65, and 35 pmol alcohol/min per mg protein. Decanoic (10:0), lauric (12:0), oleic (18:1 cis), linolenic (18:3), arachidonic (20:4), and behenic (22:0) acids all gave lower activities. Acyl-CoA formation did not appear to be rate limiting with any of the substrates tested except behenic acid. In addition to the fatty alcohol product, a small amount of fatty aldehyde was formed in the system. Incorporation of the labeled fatty acids into wax esters was examined and the distribution of label between the alcohol and acid components of the waxes was determined. Incubation of [1-(14)C]palmitic acid yielded 3.4% free alcohol, 8.3% alcohol esterified in waxes, and 7.7% palmitoyl groups esterified into waxes, whereas, at the other extreme, [1-(14)C]linolenic acid yielded 0.8%, 0.6%, and 38%, respectively, into the homologous components.-Wykle, R. L., B. Malone, and F. Snyder. Acyl-CoA reductase specificity and synthesis of wax esters in mouse preputial gland tumors.

Animals↗
PubMed1978

The relationship between changes in REM sleep and clinical improvement in depressed patients treated with amitriptyline.

EEG sleep recordings were obtained on consecutive nights from six hospitalized depressed patients before, during, and after treatment with amitriptyline for a total of 370 nights of data, about 85% of all nights of the study. Amitriptyline significantly reduced time spent in rapid eye movement (REM) sleep and prolonged the REM latency throughout the treatment period. Three patients who improved during treatment showed a REM rebound when amitriptyline was discontinued, whereas three patients who did not improve showed no REM rebound.

Aged↗
PubMed1978

Effect of a choline inhibitor (N-isopropylethanolamine) on cellular metabolism of L-M cells.

N-Isopropylethanolamine, a choline analog, is incorporated into L-M cell lipids as 1,2-diacyl-sn-glycero-3-phosphoisopropylethanolamine de novo and not by base exchange. In addition, the N-isopropylethanolamine effectively blocks choline uptake, which is a reversible process. The following specific time-dependent changes in cell metabolism also occur when N-isopropylethanolamine is present: (1) a decrease in total content of phosphatidylcholine, (2) inhibition of both the cellular uptake of [3H]choline and its incorporation into phosphatidycholine, (3) a decrease in the incorporation of [3H]thymidine into DNA as early as 2 h after initiating the N-isopropylethanolamine block, (4) inhibition of the cellular uptake of [3H]uridine and incorporation into RNA 16--24 h after addition of the N-isopropylethanolamine, and (5) stimulation of the cellular uptake of [3H]leucine and an inhibition of its incorporation into protein, which reached a maximum (68% of controls) 8 h after N-isopropylethanolamine treatment.

Cells, Cultured↗
PubMed1978

Membrane lipid modifications: biosynthesis and identification of phosphatidyl-N-methyl-N-isopropylethanolamine in rat liver microsomes.

In previous studies on the modification of polar head groups of membrane phospholipids with the unnatural base analog, N-isopropylethanolamine, we reported an unidentified phospholipid in addition to phosphatidyl-N-isopropylethanolamine in the various membrane fractions of rat liver. The structure of this phospholipid has now been identified as phosphatidyl-N-methyl-N-isopropylethanolamine by nuclear magnetic resonance spectroscopy, and by chromatographic and enzymic analysis. In addition, we found that when rats were injected intraperitoneally with the N-methyl-N-isopropylethanolamine, 19% of the liver microsomal phospholipid was phosphatidyl-N-methyl-N-isopropylethanolamine.

Animals↗
PubMed1977

Evidence for participation of cytochrome b5 in microsomal delta-6 desaturation of fatty acids.

The delta-6 desaturation of linoleic acid to gamma-linolenic acid and oleic acid to 6,9-octadecadienoic acid by rat liver microsomes was investigated. Using a specific antibody prepared against purified rat liver cytochrome b5, we demonstrated that cytochrome b5 participated in delta-6 desaturation of both fatty acids. The reaction products were identified as their methyl ester derivatives by argentation thin-layer chromatography, gas-liquid chromatography, and reductive ozonolysis followed by gas-liquid chromatography.

Animals↗
PubMed1977

Properties of dihydroxyacetone phosphate acyltransferase in the harderian gland.

We have used a microsomal preparation from the pink portion of the rabbit harderian gland to study the properties of dihydroxyacetone-P acyltransferase. The enzymatic activity in the microsomes is latent and is stimulated approximately 20-fold by the addition of detergent to the assay system. Both deoxycholate and cholate stimulated the enzyme at concentrations considerably below the critical micellar concentration of these detergents. The acyltransferase was not solubilized by treatment with these detergent concentrations. In addition, we have shown that the acyltransferase is sensitive to proteolytic digestion in the presence of deoxycholate concentrations that render the microsomal vesicles permeable to the protease, but is insensitive to the protease treatment in the absence of detergent. Collectively, these data indicate that the active site of dihydroxyacetone-P acyltransferase is exposed to the lumenal surface of the microsomal vesicles. This enzyme is distinct from the glycerol-P acyltransferase in that the dihydroxyacetone-P acyltransferase is sensitive to protease digestion only in the presence of deoxycholate, is not inhibited by sulfhydryl reagents, and is not competitively inhibited by sn-glycerol-3-P.

Acyltransferases↗