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Biomedical subjects

J M Kauffman

Publications and source records attributed to J M Kauffman.

At least 19 recordsLinked to original sources
PubMed2000

Fluorocholesterols, in contrast to hydroxycholesterols, exhibit interfacial properties similar to cholesterol.

We used an automated Langmuir-Pockels surface balance to characterize the air-water interfacial properties of cholesterol (CH) and its derivatives with hydrophilic OH and F substitutions at isologous sites on the sterol body or side chain. We studied 6-fluorocholesterol, 25-fluorocholesterol, 25,26,26,26,27,27,27-heptafluorocholesterol, 7alpha-hydroxycholesterol, 7beta-hydroxycholesterol, 25-hydroxycholesterol and 27-hydroxycholesterol, alone and in mixtures with 1-palmitoyl-2-oleoyl-sn-3-glycero-phosphocholine (POPC). Pressure;-area isotherms of the fluorocholesterols were essentially indistinguishable from CH and all condensed POPC monomolecular layers (monolayers) to variable degrees. Both nucleus-substituted hydroxycholesterols formed expanded monolayers, with lift-offs from baseline 22-26 A(2)/molecule larger than CH, suggesting interfacial tilting; furthermore, in binary mixtures, they condensed POPC monolayers less than CH. In contrast, the side chain hydroxylated CHs were oriented horizontally in the interface at large molecular areas, and became vertical below 140 A(2)/molecule with the side chain-OH rather than 3-OH group anchored in the subphase, as evidenced by low collapse pressures and smaller molecular areas than CH. Both side chain hydroxycholesterols expanded POPC monolayers at molar ratios <30%, but induced condensation with higher ratios, suggesting that OH-acyl chain (POPC) repulsion is superceded at higher mole fractions by lateral phase separation and intersteroidal H-bonding. These studies predict that fluorocholesterols should exhibit intramembrane spatial occupancy nearly identical to CH, whereas nucleus and especially side chain hydroxycholesterols will perturb membrane lipid packing notably.

Cholesterol↗
PubMed1994

Places of change: special education's power and identity in an era of educational reform.

Special education is in danger of disintegration due to (a) justified criticisms of implementational failures, and (b) unjustified criticisms from reformers and detractors, mostly having to do with its conceptualization and the separate placement of some students with disabilities. Needed reforms in special education include (a) constructing defensible rival philosophies, (b) improving the preparation and support of special education teachers, and (c) putting educational methods on a sound scientific footing.

Adolescent↗
PubMed1993

Personnel training: a key aspect of a quality program in the chemical process industry.

Effective training is key to quality improvement activities and should be organized as a system which integrates core company principles, has high professional standards, is appropriate to the technology, has management support, and meets employee needs. This paper deals with a training and awareness program required for quality assurance systems in the chemical process industry. Practical examples are provided.

Chemical Industry↗
PubMed1990

Synthesis and structure-activity relationships of anti-inflammatory 9,10-dihydro-9-oxo-2-acridine-alkanoic acids and 4-(2-carboxyphenyl)aminobenzenealkanoic acids.

Eighteen test compounds, in three chemical series, were prepared as potential anti-inflammatory agents and evaluated by the rat hindpaw carrageenan-induced edema assay. The compounds, isosteric with known anti-inflammatory and antiallergic cyclo-oxygenase and lipoxygenase inhibitors, are 10-methyl-9,10-dihydro-9-oxo-2-acridinealkanoic acids, 9,10-dihydro-9-oxo-2-acridinealkanoic acids, and 4-(2-carboxyphenyl)aminobenzenealkanoic acids. Compounds within each of these series differ in the structure of the alkanoic acid side chain. Compounds containing the acetic acid and the branched 2-propionic acid side chain showed inhibition of carrageenan-induced edema. The activity of compounds with these side chains and the inactivity of those with carboxy, oxyacetic, thioacetic, and 3-propionic acid side chains is in accordance with the proposed template model of Appleton and Brown for the active site of cyclo-oxygenase, rather than with the alternative active site model proposed by Gund and Shen. One compound, (+-)-2-[N-(2-carboxyphenyl)-4-aminophenyl]propionic acid (3c), showed edema inhibition at 50 mg/kg po, comparable to that of an equivalent dose level of (+)-naproxen. Compounds 4a and 5a, which contain a carboxylic acid side chain, exhibited inhibition of soybean 12-lipoxygenase with IC50 values of 17.2 and 8.4 microM, respectively. The inhibition observed for the control drug, naproxen, was 24 microM.

Acridines↗
PubMed1986

Cocoa butter biosynthesis. Purification and characterization of a soluble sn-glycerol-3-phosphate acyltransferase from cocoa seeds.

Glycerol-3-phosphate acyltransferase has been purified from the post-microsomal supernatant of cocoa seeds using differential ammonium sulfate solubility along with anion exchange and gel filtration chromatography. Chromatofocusing and isoelectric focusing revealed a series of proteins with acyltransferase activity having isoelectric points close to 5.2. Gel filtration on Sephacryl S-300 in 500 mM NaCl, along with polyacrylamide gel electrophoresis (denaturing and non-denaturing) and immunochemical analysis, gave evidence that the native enzyme has a molecular weight of 2 X 10(5) and consists of an aggregate of 10 Mr 20,000 subunits. The highly purified enzyme carries an acyl donor, probably acyl-CoA, although this is not firmly established. The hydrophobic nature of the purified enzyme was demonstrated by its firm binding to octyl-Sepharose. Mass spectrometric analysis of reaction products revealed the presence of both palmitic and stearic acids. Considering that 1) the fatty acids were derived from the purified enzyme; 2) they were found exclusively in the 1-position of glycerol 3-phosphate; 3) the fatty acid positioning and composition is consistent with that found in cocoa butter, the major storage product of cocoa seeds; and 4) the enzyme is found in the post-microsomal supernatant, it seems reasonable to conclude that the first step in cocoa butter biosynthesis is catalyzed by glycerol-3-phosphate acyltransferase in the cytoplasm of cocoa cotyledon cells.

Acyltransferases↗
PubMed1983

Synthesis and antileukemic activity of 2-(2-methylthio-2-aminovinyl)-1-methylquinolinium iodides.

Reaction of 2-bis(2-methylthio)vinyl-1-methylquinolinium iodide with several heterocyclic aliphatic amines at 30-70 degrees resulted in replacement of one methylthio group to give the title compounds. Reaction with pyrrolidine gave an unidentified product lacking sulfur. Antileukemic screening against P-388 lymphocytic leukemia showed positive activity only with the 6-methyl-morpholino derivative, whereas the 6-unsubstituted morpholino derivative was inactive. This result is in contrast to previous testing results with the 2-bis(2-methylthio)vinyl compounds where both 6-substituted and 6-unsubstituted derivatives showed activity.

Animals↗
PubMed1983

Insulin resistance in uremia. Characterization of insulin action, binding, and processing in isolated hepatocytes from chronic uremic rats.

We have developed a model in the rat that leads to a predictable degree of severe uremia to study the role of the liver in the insulin-resistant state of uremia. The uremic animals were euglycemic and had increased serum immunoreactive insulin when compared with their pair-fed controls. Insulin action, binding, internalization, and degradation were characterized in freshly isolated hepatocytes from uremic animals, sham-operated pair-fed, and ad lib.-fed controls. The basal rate of aminoisobutyric acid (AIB) uptake was increased in hepatocytes from both uremic and pair-fed control rats. However, while hepatocytes from uremic animals were refractory to insulin with regard to AIB uptake, there was no significant difference in the absolute increment above basal AIB uptake by hepatocytes from pair-fed and fed ad lib. animals at any insulin concentration studied. 125I-Insulin binding at 24 degrees C was higher in hepatocytes from uremic rats at every insulin concentration studied when compared with fed ad lib. controls. The time course of 125I-insulin binding to the cell and to the fractions that were membrane bound or internalized were studied at 37 degrees C. An increase in membrane-bound 125I-insulin at 37 degrees C was present also in hepatocytes from uremic animals. The same fraction of membrane-bound 125I-insulin was internalized in hepatocytes from all groups of animals. Extracellular and receptor-mediated 125I-insulin degradation at the plasma membrane and after internalization was studied at 37 degrees C by gel chromatography. There was a delayed and decreased rate of 125I-insulin degradation in hepatocytes from uremic rats in the three compartments. We conclude: (a) In chronic uremia the liver is refractory to insulin with regard to AIB uptake. (b) Insulin resistance in uremic rat liver is not due to defects in insulin binding or internalization. (c) Despite the high level of circulating immunoreactive insulin, hepatocytes from uremic rats did not show the expected "down regulation" of their insulin receptors or an increased rate of insulin degradation. These studies further emphasize the primary role of postbinding events in the regulation of insulin binding and degradation. The mechanism as to how the coordinated steps of insulin metabolism in the liver are disrupted in a pathological state is presently unknown.

Animals↗
PubMed1982

Synthesis of omega-(4-aminophenylsulfonamido)alkyl disulfides and thiosulfates and their activity against dihydropteroate synthetase from sulfanilamide-resistant Neisseria gonorrhoeae.

A series of omega-(4-aminophenylsulfonamido)alkyl disulfides and omega-(4-aminophenylsulfonamido)alkanethiosulfates was synthesized from the reaction of p-acetamidobenzenesulfanilyl chloride and either the aminoalkyl disulfide dihydrobromide or the aminoalkyl bromide hydrobromide followed by sodium thiosulfate. Several of the compounds showed inhibitory activity against dihydropteroate synthetase isolated from a sulfanilamide-resistant strain of Neisseria gonorrhoeae of the same order of activity as that of sulfanilamide. An increase in the hydrophobic nature of the sulfanilamide structure did not increase inhibitory activity against this enzyme.

Chemical Phenomena↗
PubMed1980

Antileukemic activity of 2-bis(2-methylthio)vinyl-1-methylquinolinium iodides.

Reaction of 1-methylquinolinium-2-dithioacetic acid zwitterions with excess methyl iodide in dimethylformamide gave the corresponding bis(2-methylthio)vinyl derivatives. These compounds were more soluble in both aqueous and organic media than the dithioacetic acid zwitterions but showed comparable antileukemic activity in mice. Reaction with morpholine converted a bis(2-methylthio)vinyl derivative almost quantitatively to the 2-mono(methylthio)-2-morpholino derivative. Leukemia cell culture studies of the 6-methyl derivative showed no effect on cell cycle processes.

Animals↗