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Biomedical subjects

J Ralph

Publications and source records attributed to J Ralph.

7 recordsLinked to original sources
PubMed1991

Synthesis of methyl 5-O-trans-feruloyl-alpha-L-arabinofuranoside and its use as a substrate to assess feruloyl esterase activity.

A synthetic scheme was developed for the production of methyl 5-O-trans-feruloyl-alpha-L-arabinofuranoside (FA-Ara) in gram quantities. This molecule accurately models the chemical attachment of ferulic acid to polysaccharides found in cell walls of plants in the Gramineae family. It is therefore a realistic substrate that can be used to monitor feruloyl esterase activity. Ultraviolet spectral analysis indicated that FA-Ara has an absorption maximum distinct from the hydrolytic product, ferulic acid (FA), over a wide range of solution pH values. The log molar extinction coefficient ranges from 4.16 to 4.36 for FA-Ara and 4.16 to 4.33 for FA depending upon the pH of the buffered solution. Consequently a convenient spectrophotometric assay can be utilized to monitor esterase activity. Three different methods were developed for using this model substrate to assess esterase activity, including thin-layer chromatography, a spectrophotometric assay, and the use of high-performance liquid chromatography.

Arabinose↗
PubMed1990

Synthesis of affinity ligands and radioactive probes for isolation and study of myo-inositol 1,4,5-trisphosphate binding proteins.

To synthesize an affinity matrix for isolation of D-myo-inositol 1,4,5-trisphosphate binding proteins, racemic 3-cyclohexene-1-carboxaldehyde was oxidized and converted to a mixture of trans-3,4-di-hydroxycyclohexane-1-carboxylic acid methyl ester isomers, which was phosphorylated and separated into (+-)-(1R,3R,4R)- and (+-)-(1R,3S,4S)-trans-3,4-bis[(diphenoxyphosphoryl)oxy]cyclohex an e-1- carboxylic acid methyl esters. Each of these racemic compounds was hydrogenolyzed and reacted with ethylenediamine to give a monoamide, N-(2-aminoethyl)-bis(phosphonyloxy)cyclohexane-1-carboxamide, that was coupled to cyanogen bromide activated Sepharose 4B to provide the desired affinity matrices. The intermediate trans-3,4-bis[(diphenoxyphosphoryl)oxy]cyclohexane-1-carboxylic acid methyl ester was also reduced with lithium borotritide to give the (hydroxy[3H]methyl)cyclohexane derivative, which was phosphorylated and hydrogenolyzed to yield trans-3,4-bis(phosphonyloxy)-1-[(phosphonyloxy)[3H]methyl]cy clohexane, a radiolabeled analogue of inositol 1,4,5-trisphosphate. The carboxamide was also coupled to 4-azidosalicylic acid, and the product was iodinated to provide a 125I-radiolabeled photoactivatable cross-linking derivative of cyclohexanediol bisphosphate.

Calcium Channels↗
PubMed1989

Morphological alterations in cultured neuromuscular tissue induced by two anesthetic agents.

A diversity of pathogenic effects was observed in two complementary culture systems following their exposure to the anesthetic agents. Thiopental sodium and ketamine hydrochloride. The cytotoxic effects of both agents in these two culture types were reversible and dose-related. In organotypic spinal cord slice cultures, thiopental sodium caused general toxicity but no demyelination, while ketamine hydrochloride induced, to a varied extent, damage of the myelin sheath and degeneration of mitochondria into multilamellar bodies. In autologous nerve-muscle co-cultures both anaesthetic agents caused the arrest of muscle contractions. However, when added to skeletal muscle cultures, the drugs differed in their effect. Thiopental sodium did not inhibit spontaneous muscle contractions indicating, as in the case of Tubocurarine, a direct effect of the drug on the neuromuscular junction. Ketamine hydrochloride, in contrast, arrested spontaneous muscle contractions, implying that it did not directly affect the neuromuscular synapse.

Anesthetics↗
PubMedDate not supplied

Enhancing the coping skills of mothers with developmentally delayed children.

Recent studies have shown that mothers of developmentally delayed children are at risk for depression. During weekly psychoeducational group meetings, Roy's adaptation model was used to identify the focal, contextual, and residual stimuli that contributed to the mothers' depression. Nursing interventions that encouraged adaptation in the four modes were implemented by group facilitators providing parent education and emotional support. Implications for nurses in a variety of settings are given.

Adaptation, Psychological↗
PubMedDate not supplied

Operation cataract.

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Aged↗