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Biomedical subjects

M Jay

Publications and source records attributed to M Jay.

At least 163 records · Page 9Linked to original sources
PubMed1985

Purification, properties and kinetic mechanism of flavonol 8-O-methyltransferase from Lotus corniculatus L.

A novel O-methyltransferase catalyzing the transfer of the methyl group of S-adenosyl-L-methionine to the 8-hydroxyl group of flavonols was purified about 1200-fold from Lotus flower buds, by precipitation with ammonium sulfate and successive chromatography on columns of Sephadex G-100, S-adenosyl-L-homocysteine--Agarose, hydroxyapatite and Polybuffer ion exchanger. The enzyme exhibited strict specificity for position 8 of 8-hydroxyquercetin and 8-hydroxykaempferol, a pH optimum at 7.9, a pI value of 5.5, an Mr of 55 X 10(3) and required Mg2+ and SH groups for activity. The Km values for 8-hydroxykaempferol and S-adenosyl-L-methionine were 1.3 microM and 53 microM, respectively. The data obtained from substrate interaction and product inhibition studies are expected for a steady-state ordered bi-bi mechanism, with 8-hydroxyflavonol binding before S-adenosyl-L-methionine followed by the release of S-adenosyl-L-homocysteine and 8-methoxyflavonol. An alternative mechanism that may also fit the data is the mono-iso Theorell-Chance with the inverse binding sequence and an isomerization step of the free enzyme.

Buffers↗
PubMed1985

In vivo dissolution measurement with indium-111 summation peak ratios.

Dissolution of [111In]labeled tablets was measured in vivo in a totally noninvasive manner by using a modification of the perturbed angular correlation technique known as the summation peak ratio method. This method, which requires the incorporation of only 10-12 microCi into the dosage form, provided reliable dissolution data after oral administration of [111In]lactose tablets. These results were supported by in vitro experiments which demonstrated that the dissolution rate as measured by the summation peak ratio method was in close agreement with the dissolution rate of salicylic acid in a [111In]salicylic acid tablet. The method has the advantages of using only one detector, thereby avoiding the need for complex coincidence counting systems, requiring less radioactivity, and being potentially applicable to a gamma camera imaging system.

Indium↗
PubMed1985

Elastin fragment-induced monocyte chemotaxis. The role of desmosines.

Elastin fragments generated by the digestion of human and bovine elastin were compared to fragments which had been treated with sodium borohydride for their ability to induce monocyte chemotaxis. No significant decrease in the number of migratory cells was observed between the two groups. Elastin fragments denatured with 8 M urea were devoid of chemotactic activity. These results support the premise that the tertiary structure of elastin fragments and not desmosine content is the most important structural determinant in the induction of elastin fragment-induced monocyte chemotaxis.

Amino Acids↗
PubMed1985

Interaction of ethanol with 111In-labelled membranes: evaluation by the perturbed angular correlation-sum peak ratio method.

The interaction of ethanol with erythrocyte ghosts and vesicles composed of brain lipid extracts labelled with indium-111 was studied using the sum peak ratio method of perturbed angular correlation measurements. Membranes from animals that were fed diets containing ethanol for 10 days demonstrated resistance to the decrease in sum peak ratio values observed in control animals. Thus, repeated administration of ethanol induces changes in the properties of biological membranes, possibly by altering phospholipid composition, which is reflected in the anisotropy of membrane-associated 111In-labelled nuclei as measured by sum peak ratios.

Animals↗
PubMed1985

Disposition of radiolabelled suppositories in humans.

The disposition of Witepsol H 15 suppositories radiolabelled with [99mTc] technetium hydroxymethyldiphosphonate was studied after rectal administration in volunteers. The migration of the radiolabel was monitored continuously by external scintigraphy. The resulting scintiphotos were superimposed on lower GI radiographs to determine the extent of spreading of the dosage form in the rectum. The dosage form migrated approximately 5-7 cm into the rectum in nearly all of the studies and was, in general, confined to the lower and middle regions of the rectum. Since the venous supply to the lower rectum leads primarily to the inferior vena cava, the data presented here indicate that the metabolism of drugs sensitive to the 'first-pass' effect may be partially avoided by their rectal administration.

Adult↗
PubMed1985

Lung myeloperoxidase as a measure of pulmonary leukostasis in rabbits.

Pulmonary leukostasis can be associated with acute lung injury. We studied lung peroxidase activity using myeloperoxidase (MPO) as a granulocyte marker to quantitate pulmonary leukostasis in rabbits. Lungs were homogenized in detergent, freeze-thawed, sonified, and centrifuged, and supernatants were assayed for MPO. Seven extractions were performed, and greater than 80% of cumulative MPO was found in the first three extractions. By use of a three-extraction procedure, the mean lung MPO (delta A X min-1 X g tissue-1) was determined in normal [20.9 +/- 5.2 (SE)], granulocyte-depleted (6.5 +/- 2.0), saline-injected (22.2 +/- 5.6), and pneumococcus (PNC)-challenged (69.7 +/- 10.6) animals. Lung MPO was significantly decreased in granulocyte-depleted compared with normal animals (P less than 0.005) and significantly increased in PNC-challenged compared with saline-injected animals (P less than 0.001). MPO extracted from granulocytes and lungs from normal as well as PNC-challenged animals were all biochemically identical. Lung extract did not inhibit MPO, and no MPO was detected in bronchoalveolar lavage fluid obtained from leukostatic lungs. Lung MPO significantly (P less than 0.01) correlated with intravascular intrapulmonary granulocytes. Determination of lung MPO is a relatively simple quantitative method that can be used to detect pulmonary leukostasis.

Animals↗
PubMed1985

Recombinant DNA technology.

The advent of new techniques in the study of DNA has generated great interest among clinicians in their application to genetic disorders. These new techniques are outlined, and their application in the study of X-linked disorders, in particular X-linked retinitis pigmentosa (RP), is described. This concerns chiefly the use of probes in studying DNA sequences on a given chromosome and the basic principles which govern their application.

Alleles↗
PubMed1985

Bone scanning in Waldenstrom's macroglobulinemia.

We present a case report of a remarkably positive bone scan in a patient known to be suffering from Waldenstrom's macroglobulinemia. Although bone involvement in this disease was originally thought not to be present, reports of bone involvement are becoming more frequent. Documenting the presence and extent of bone involvement is important because local palliative radiotherapy and/or orthopedic measures, similar to those recommended for patients suffering from multiple myeloma, may be required to prevent pathologic fractures and patient discomfort.

Aged↗
PubMed1983

The Eisdell pedigree. Congenital stationary night-blindness with myopia.

A pedigree of X-linked congenital stationary night-blindness, originally published by Nettleship, is presented with abstracts from his private correspondence. An affected descendant has supplied letters and the original working pedigree which led to the publication of the extended pedigree in 1912.

Female↗
PubMed1983

DNA probes in X-linked retinitis pigmentosa.

Informative members of more than twenty families with X-linked retinitis pigmentosa have been sampled by venipuncture and DNA extracted from peripheral blood leucocytes and lymphoblastoid cell lines. X chromosome-specific recombinant DNA probes have been isolated from an X chromosomal genomic DNA library obtained by flow-sorting human chromosomes. These, and similar probes obtained from other laboratories, are being used to identify restriction fragment length polymorphisms in retinitis pigmentosa obligate heterozygotes. By analysis of linkage relationships in the offspring of double heterozygotes, it may be possible to localize the gene(s) responsible for this disorder to a particular subregion of the X-chromosome. Such probes are potentially useful for carrier detection and prenatal diagnosis.

Adolescent↗
PubMed1982

Enhanced entrapment of a quaternary ammonium compound in liposomes by ion-pairing.

The encapsulation of a quaternary ammonium compound by multilamellar liposomes was enhanced by formation of ion-pairs with a counterion. Thus, [14C]methantheline bromide was synthesized and paired with a 25 M excess of trichloroacetate. Under these conditions, the amount of radioactivity entrapped by phosphatidylcholine liposomes was three times greater than when no trichloroacetate was present. The increased liposomal loading was probably due to the solubilization of the ion-pair in the lipid membrane of the liposome.

Chemical Phenomena↗
PubMed1982

On the heredity of retinitis pigmentosa.

The aims of this study are: (1) to determine the frequencies of the various genetic forms of retinitis pigmentosa; and (2) to perform segregation analysis on autosomal dominant, autosomal recessive, and X-linked families. The families studied consisted of 2 series of patients at Moorfields Eye Hospital: (1) 426 families seen in the Genetic Clinic; and (2) 289 families seen in the Electrodiagnostic Department. Comparison between the 2 series identified biases of ascertainment, and it was estimated that the combined series included 53% of simplex cases and a minimum of 15% of X-linked families. Segregation analysis of the Genetic Clinic series showed good agreement with expectation in autosomal dominant and X-linked families, but indicated that no more than 70% of all simplex cases were autosomal recessive. The rest of the simplex cases were mildly affected and may represent fresh autosomal dominant mutations, autosomal dominant transmission with reduced penetrance, the heterozygous state of X-linked disease in some of the females, and phenocopies.

Female↗
PubMed1982

Linkage and chromosomal studies in congenital cataract.

The methods used in linkage and chromosomal studies in congenital cataract are described. These are: classical pedigree analysis with the detection of recombinants among the offspring of informative matings, and somatic cell hybridization. The recently developed methods using recombinant DNA techniques are briefly mentioned.

Cataract↗
PubMed1980

Angiographic evaluation of post-sternotomy arteriovenous fistula of the internal mammary artery and vein.

An arteriovenous fistula of the right internal mammary artery and vein following median sternotomy was demonstrated by angiography. This surgical complication has not been previously reported in the literature, despite the recent increase in cardiac surgery via median sternotomy. Clinical and radiologic awareness of this iatrogenic shunt and of its potential delayed appearance and cardiovascular effects are important. Arteriovenous fistulas are usually treated by surgical ligation and excision, or by transcatheter occlusion therapy.

Aged↗