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Biomedical subjects

R M Stewart

Publications and source records attributed to R M Stewart.

104 records · Page 6Linked to original sources
PubMed1976

Glutamate accumulation by human gliomas and meningiomas in tissue culture.

The rapid accumulation of radioactive glutamate was studied in human brain tumor cells grown in tissue culture. The MGH-LM line of human astrocytoma demonstrated both a high (apparent Km = 20 muM) and a low (apparent Km = 0.2 mM) affinity component for the uptake of glutamate. The high affinity component was sodium-, temperature-, and energy-dependent and was present during the confluent (stationary) but not the log phase of cell growth. A study of confluent monolayer cultures of several other human brain tumors revealed that a similar high affinity uptake of glutamate occurred in 7 out of malignant astrocytomas and appeared to be independent of the grade of malignancy. In 3 optic gliomas and 5 meningiomas studied, low but not high affinity uptake of glutamate was found. These studies suggest that glial cells in the human brain may in some instances possess uptake characteristics for glutamate similar to those previously ascribed to nerve endings.

Astrocytoma↗
PubMed1976

Regional lung function in ankylosing spondylitis.

Xenon-133 was used to study regional pulmonary function in nine patients with chest cage rigidity due to ankylosing spondylitis. In comparison with normal subjects, the patients showed an overall diminution in lung volume and the proportion of inhaled xenon reaching the lung apices was reduced but the distribution of injected xenon was normal. The possible relationship between these findings and apical lung disease in ankylosing spondylitis is mentioned.

Adult↗
PubMed1976

Regional lung function in unilateral diaphragmatic paralysis.

Radioactive xenon-133 was used to study the regional lung function of five patients with unilateral diaphragmatic paralysis unassociated with intrathoracic disease. All patients showed a reduction in total lung capacity to which the affected side contributed an average of 37%. There was a decrease in the amount of inhaled xenon and a lesser decrease in the amount of injected xenon reaching the lung base on the paralysed side.The distribution in the opposite lung did not differ significantly from that found in normal subjects although the proportion of inhaled xenon reaching the lung base was rather less than in the normal group. The washout of injected xenon was normal except for slight impairment at the lung base on the paralysed side in one patient and at both bases in another.

Adult↗
PubMed1976

The pituitary-thyroid axis in adults with phenylketonuria.

Serum thyroxine and triiodothyronine levels in 15 adult phenylketonuric patients on an unrestricted diet were normal despite reduced circulating tyrosine levels. Serum thyrotropin levels were normal in the basal state or in response to thyrotropin-releasing hormone in selected patients tested. These results support and extend previous observations of normal thyroid function in phenylketonuria.

Adolescent↗
PubMed1976

Myoclonus after 5-hydroxytryptophan in rats with lesions of indoleamine neurons in the central nervous system.

A myoclonic syndrome consisting of tremor, myoclonus, and seizures was produced following the systemic administration of 5-hydroxytryptophan to adult rats previously given intracisternal injections of 5,7-dihydroxytryptamine and systemic desmethylimipramine, but not in their controls. This behavioral response was blocked by pretreatment with the putative serotonin receptor blocking agents methysergide, lysergic acid diethylamide, and bromolysergic and diethylamide, as well as centrally effective doses of the aromatic amino acid decarboxylase inhibitor Ro4-4602. Blockers of receptors of other neurotransmitters had little effect. This neurologic response in the adult rat may be relevant to some forms of clinical myoclonus and may be useful in testing potential agonists and antagonists of serotonin receptors in the mammalian central nervous system.

5-Hydroxytryptophan↗
PubMed1975

Lissencephaly and Pachygyria: an architectonic and topographical analysis.

The architectonic features of abnormal cerebral cortex in a brain with lissencephaly and pachygyria suggest that neuronal migration was interrupted by cortical and subcortical laminar necrosis in the fourth fetal month. The severest cortical abnormality lies in the distal perfusion fields of the major cerebral arteries, while the normal areas are located in the proximal perfusion fields. These architectonic and topographic features suggest that intra-uterine hypoxia or perfusion failure may be a pathogenetic mechanism leading to lissencephaly and pachygyria.

Brain↗
PubMed1971

Fitness to fly?

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Aerospace Medicine↗