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Biomedical subjects

M D O'Brien

Publications and source records attributed to M D O'Brien.

At least 55 records · Page 3Linked to original sources
PubMed1980

Neuralgic amyotrophy.

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Brachial Plexus Neuritis↗
PubMed1980

Studies of the structure-function relationships of Neurospora pyruvate kinase: denaturation by urea and the effect of ligands on the refolding and renaturation process.

1. The renaturation of Neurospora pyruvate kinase following denaturation with urea was investigated. 2. The substrates, phosphoenol pyruvate and adenosine diphosphate, were observed to stabilize the enzyme against urea-induced structural disorganization. 3. It was demonstrated that for refolding/reactivation of the denatured protein the allosteric activator, fructose-1,6-diphosphate and a sulphydryl protectant are required. 4. The enzyme recovered following renaturation showed complete immunological identity with the native enzyme in Ouchterlony double diffusion tests.

Adenosine Diphosphate↗
PubMed1980

Studies of the structure--function relationships of Neurospora crassa pyruvate kinase: interaction with blue dextran--sepharose and Cibacron blue 3G-A.

Blue dextran--Sepharose and Cibacron blue 3G-A interact with pyruvate kinase of Neurospora crassa. The enzyme is readily released from the substituted Sepharose column by elution with 0.17 M potassium phosphate buffer (pH 7.9), or 2 mM fructose 1,6-diphosphate (FDP), but not with either of the substrates, ADP and phosphoenolpyruvate (PEP), at 2 mM. Cibacron blue 3G A is a noncompetitive inhibitor of pyruvate kinase with respect to both substrates. It appears to compete with the allosteric effector, FDP, for binding to the enzyme surface. A lack of elution of the enzyme from the immobilized blue dextran matrix by adenine nucleotides and the absence of a difference spectrum in the 650- to 700-nm range suggest that a "dinucleotide-fold" substructure is not implicated in the dye binding sites on pyruvate kiase. The interaction of Cibacron blue 3G-A and this enzyme can be followed fluorometrically; incremental additon of the dye to the enzyme solution results in a progressive decrease in the fluorescence of surface tryptophanyl residues. The quenching of fluorescence of exposed aromatic groups is subject to reversal following addition of FDP to the pyruvte kinase--Cibacron blue complex.

Adenosine Diphosphate↗
PubMed1979

Embolization of traumatic aneurysm of the maxillary artery.

An expanding false aneurysm in the infratemporal fossa followed this patient's complicated jaw fracture. Successful Gelfoam embolization of the maxillary artery has controlled haemorrhage, treated the aneurysm, and avoided the hazards of local operative intervention. The technique of embolization has a place in the management of various difficult vascular problems.

Adolescent↗
PubMed1978

Diabetes and the family.

The reaction of the family to the presence of chronic illness depends on the composition of the family, the presence of significant others, the cultural background, the education of family members, the stage of family development, and finally the health-belief model adopted by the family.

Adaptation, Psychological↗
PubMed1977

Investigation of the quaternary structure of Neurospora pyruvate kinase by cross-linking with bifunctional reagents: the effect of substrates and allosteric ligands.

Pyruvate kinase (EC 2.7.1.40) of Neurospora, a tetramer composed of apparently identical subunits, has been shown to be a dimer of dimers by interprotomeric cross-linking experiments in which bifunctional reagents were used. An analysis of the polyacrylamide gel profiles of the enzyme after cross-linking with glutaraldehyde, dimethyl suberimidate, and dimethyl adipimidate shows that the extent of intersubunit cross-linking is influenced markedly by the ligand bound to the enzyme. Bifunctional cross-linking reagents with a shorter distance between the two functional groups form cross-links effectively in the unliganded enzyme. In the FDP-pyruvate kinase complex, cross-linking was observed over longer distances compared with the unliganded enzyme. It is demonstrated that covalent cross-linkers cah be used as sensitive indicators of conformational changes induced in pyruvate kinase by substrates and allosteric ligands.

Adipates↗
PubMed1975

Failure to confirm a vascular cause of muscular dystrophy.

The vascular hypothesis of the cause of muscular dystrophy suggests that ischemia is responsible for the muscle fiber necrosis. A xenon 133 clearance study of muscle blood flow in Duchenne and other muscular dystrophies showed no obvious difference between the response to exercise and arterial occlusion compared with control subjects. Radioautographic study of distribution of 4-125l-antipyrine in skeletal muscle of mice with muscular dystrophy showed no abnormal areas of ischemia. A statistical examination was also made of the grouping of damaged fibers, one of the observations on which the vascular hypothesis was based. Only 0.9% of fibers undergoing phagocytosis occurred in groups of four or more fibers in greater frequency than would have been expected by chance, and 70% of such fibers were isolated. These studies argue strongly against the vascular hypothesis of the cause of muscular dystrophy.

Adult↗