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Biomedical subjects

A L Laborde

Publications and source records attributed to A L Laborde.

24 records · Page 2Linked to original sources
PubMed1982

Oxidation of naphthalene by a multicomponent enzyme system from Pseudomonas sp. strain NCIB 9816.

The initial reactions in the oxidation of naphthalene by Pseudomonas sp. strain NCIB 9816 involves the enzymatic incorporation of one molecule of oxygen into the aromatic nucleus to form (+)-cis-(1R,2S)-dihydroxy-1,2-dihydronaphthalene. The enzyme catalyzing this reaction, naphthalene dioxygenase, was resolved into three protein components, designated A, B, and C, by DEAE-cellulose chromatography. Incubation of naphthalene with components A, B, and C in the presence of NADH resulted in the formation of (+)-cis-(1R,2S)-dihydroxy-1,2-dihydronaphthalene. The ratio of oxygen and NADH utilization to product formation was 1:1:1. NADPH also served as an electron donor for naphthalene oxygenation. However, its activity was less than 50% of that observed with NADH. Component A showed NAD(P)H-cytochrome c reductase activity which was stimulated by the addition of flavin adenine dinucleotide and flavin mononucleotide. A similar stimulation was observed when these flavin nucleotides were added to the naphthalene dioxygenase assay system. These preliminary observations indicate that naphthalene dioxygenase has properties in common with both monooxygenase and dioxygenase multicomponent enzyme systems.

Alcohol Oxidoreductases↗
PubMed1980

3-Trehalosamine, a new disaccharide antibiotic.

3-Amino-3-deoxy-alpha-D-glucopyranosyl-alpha-D-glucopyranoside (alpha, alpha--3-trehalosamine) was isolated from a culture of Nocardiopsis trehalosei sp. nov. (NRRL 12026). The structure was determined using a combination of spectroscopic techniques on derivatives of the component sugars, especially gas chromatography-mass spectrometry. The compound exhibited antibiotic activity against Gram-positive organisms at levels similar to what was found for the 2- and 4-trehalosamines.

Animals↗
PubMed1977

Metabolism of dibenzothiophene by a Beijerinckia species.

Beijerinckia B8/36 when grown with succinate in the presence of dibenzothiophene, accumulated (+)-cis-1,2-dihydroxy-1,2-dihydrodibenzothiophene and dibenzothiophene-5-oxide in the culture medium. Each metabolite was isolated in crystalline form and characterized by a variety of chemical techniques, cis-Naphthalene dihydrodiol dehydrogenase, isolated from Pseudomonas putida, oxidized (+)-cis-1,2-dihydroxy-1,2-dihydrodibenzothiophene to a compound that was tentatively identified as 1,2-dihydroxydibenzothiophene. The same product was formed when crude cell extracts of the parent strain of Beijerinckia oxidized (+)-cis-1,2-dihydroxy-1,2-dihydrodibenzothiophene under anaerobic conditions. Further metabolism of 1,2-dihydroxydibenzothiophene by heat-treated cell extracts led to the formation of 4[2-(3-hydroxy)-thionaphthenyl]-2-oxo-3-butenoic acid. The latter compound was metabolized by crude cell extracts to 3-hydroxy-2-formylthionaphthene. Further degradation of this metabolite was not observed.

Cell-Free System↗
PubMedDate not supplied

Interleukin-1 binding, internalization, and processing in a murine osteoblastic cell line, MC3T3.E1.

We have investigated the interaction of IL-1 and its receptor on a murine osteoblastic cell line, MC3T3.E1, with regard to binding, internalization, and the fate of the receptor-ligand complex following internalization. Binding experiments indicated that this cell line possesses a high affinity receptor (Kd 1.02 x 10(-10) M) that binds both IL-1 alpha and IL-1 beta, and has approximately 6500 receptors per cell. Cross-linking experiments indicated that the receptor has a molecular weight of 100,000 daltons. Binding of IL-1 to the receptor is inhibited by the Interleukin Receptor Antagonist Protein (IRAP). These characteristics suggest that the murine osteoblastic receptor resembles that found on T lymphocytes and fibroblasts. Internalization experiments showed that this process is fairly rapid and results in degradation of the ligand and subsequent loss of degraded IL-1 from the cell. In this respect, processing of the receptor-ligand complex mimics that observed with IL-1 receptors on murine bone marrow cells, pre-B cells, and macrophages. Although the reasons for these differences are unclear, it may be that, unlike fibroblasts, osteoblasts may function as an effector cell which rapidly removes IL-1 from the immediate environment via ligand degradation while at the same time initiating bone resorption via stimulation of osteopontin biosynthesis.

Animals↗
PubMedDate not supplied

A prospective comparison of ankle/brachial indices and color duplex imaging in surveillance of the in situ saphenous vein bypass.

We performed routine postoperative surveillance of 124 consecutive in situ saphenous vein bypasses, using both ankle-brachial indices and color flow duplex imaging. Using a combination of low and high velocity criteria, color flow duplex identified 97% (37/38) of bypass and native artery inflow stenoses subsequently demonstrated by angiography, including 20 of 21 severe stenoses. A reduction in ankle-brachial index by greater than 0.15 identified 43% (16/38) of all stenoses, and only 10 of 21 severe stenoses. Revisional operations were performed in 30 bypasses for abnormalities detected by surveillance, resulting in a 3-year cumulative secondary patency of 87%. Color flow duplex is a superior technique for in situ bypass surveillance when compared to alterations in ankle-brachial indices. The identification of a bypass or inflow stenosis by routine surveillance and its subsequent operative treatment result in satisfactory long-term patency.

Aged↗