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Biomedical subjects

G Shaw

Publications and source records attributed to G Shaw.

At least 253 records · Page 14Linked to original sources

Sporopollenin. A novel, naturally occurring support for solid phase peptide synthesis.

Sporopollenin from Lycopodium clavatum has been found to be capable of acting as a solid support for peptide synthesis. It is stable to chloromethylation and to the standard deblocking procedures and its constant mesh size, ready commercial availability, and constant molecular structure give it potential important practical advantages over synthetic resins.

Biopolymers↗

Growth cone formation in cultures of sensory neurons.

Three experimental situations have been found in which cultured sensory neurons from embryonic chicken will form growth cones from positions along the length of the neurite. If the neurons are dissected with a remaining short axonal stump and plated into serum-free medium, they can form a morphologically normal growth cone from the stump within 15 min, even in the presence of cycloheximide or puromycin. When neurites growing in culture media with low levels of serum are cut at any point with microneedles, growth cones are produced quickly from the amputated stump, usually within 20 min. Treatment of growing neurons with low concentrations of colchicine, Colcemid, or podophyllotoxin results in the progressive appearance of lateral filopodia and regions of flattened cytoplasm that closely resemble growth cones except for their preterminal positions. These observations show that the potential to form growth cones is distributed throughout the neuron and suggest that this normally repressed in some way by the neuronal microtubules.

Axons↗

Some effects of mazindol, an anorectic drug, on rat brain monoaminergic systems.

Mazindol was devoid of effect both on rat brain steady state levels of 5-HT, 5-HIAA and tryptophan and on the rate of synthesis of 5-HT in the rat brain. Mazindol had no effect on rat brain 5-HT uptake in vivo as determined by the effect of drug pretreatment on the ability of p-chloroamphetamine to lower central 5-HT levels. A large dose of mazindol caused a slight transient decrease in rat brain levels of NA and DA. Blockade of rat brain catecholamine uptake was quantified by studying drug effects on the ability of intraventricularly administered 6-hydroxydopamine to lower brain NA and DA content. Mazindol was an extremely potent inhibitor of rat brain NA uptake in vivo, being 4-5 times more potent than desipramine. Mazindol also blocked rat brain DA uptake. Doses of mazindol needed to release alpha-methyl-m-tyramine from the rat striatum were appreciably greater than the corresponding doses of d-amphetamine. The neurochemical profile of mazindol bears a much closer resemblance to that of d-amphetamine than to that of fenfluramine.

Animals↗

Purification and properties of an enzyme duet, phosphoribosylaminoimidazole carboxylase and phosphoribosylaminoimidazolesuccinocarboxamide synthetase, involved in the biosynthesis of purine nucleotides de novo.

Purification and some properties of an adjacent pair of enzymes in the biosynthetic pathway to AMP, phosphoribosylaminoimidazole carboxylase (EC 4.1.1.21) and phosphoribosylaminoimidazolesuccinocarboxamide synthetase (EC 6.3.2.6), are described. The enzymes form a duet, which may be regarded as a single molecule with a dual function, or as two very similar substances.

Adenosine Monophosphate↗