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Biomedical subjects

L R Solomon

Publications and source records attributed to L R Solomon.

67 records · Page 4Linked to original sources
PubMed1980

Treatment of essential hypertension with a combination of propranolol and bendrofluazide.

The effect of conventional propranolol and bendrofluazide tablets given twice daily has been compared with an equivalent dosage combined in a single capsule given twice daily in fourteen patients with essential hypertension. Good blood pressure control was achieved on both regimes in the majority of patients and there was no significant difference in treatment response between the two regimes. Use of the combined capsule is convenient and may improve patient compliance.

Adult↗
PubMed1979

Regulation of vitamin B6 metabolism in human red cells.

The effects of pyridoxine and pyridoxal 5-phosphate (PLP) administration on pyridoxine kinase (PnK) and asparate aminotransferase (EGOT), a PLP-dependent enzyme, were studied in human red cells separated into young and old populations by density centrifugation. After a delay of 48 hr, both pyridoxine and PLP increase EGOT activity in mature red cells by activating preformed GOT apoenzyme. In addition, in young erythroid cells, pyridoxine therapy induces synthesis of PnK, while both pyridoxine and PLP induce synthesis of GOT apoprotein. Thus, PLP stimulates EGOT induction without a change in PnK activity, suggesting that PLP enters erythroid precursor cells without prior dephosphorylation. However, with both pyridoxine and PLP, the full induction of enzyme activities reflect the gradual replacement of circulating red cells by newly formed cells with higher enzyme levels. Therefore, the use of EGOT as a measure of vitamin B6 nutritional status requires recognition of the complexities of intracellular enzyme regulation.

Alanine Transaminase↗
PubMed1979

Vitamin B6 metabolism in idiopathic sideroblastic anaemia and related disorders.

Patients with idiopathic anaemias associated with abnormal sideroblasts were defined according to morphologic and ferrokinetic criteria and the haematologic and biochemical effects of vitamin B6 therapy were evaluated. While all patients presented similar clinical pictures, peripheral blood changes and bone marrow abnormalities, two distinct groups were identified by sideroblast morphology and ferrokinetics. Patients with more than 5% true ring sideroblasts in the marrow (IRSA) uniformly had marked ineffective erythropoiesis, while those with abnormal sideroblasts but few true ring forms were hypoproliferative. Measurements of red cell pyridoxine kinase (PnK) and intracellular pyridoxal 5-phosphate availability (PLP) as assessed by the activity of the PLP-dependent enzyme asparate aminotransferase (EGOT), revealed slightly decreased PnK levels in IRSA subjects but normal intracellular PLP activities in both groups. Furthermore, when treated with pyridoxine, all patients showed increases in both red cell PnK and EGOT activities which were similar to those seen in normal subjects. Treatment with PLP also effectively increased erythrocyte vitamin B6 activity. Even so, neither pyridoxine nor intramuscular PLP improved erythropoiesis as determined by serial haematocrits, reticulocyte counts and erythron iron turnover measurements.However, since both therapies increased red cell protoporphyrin levels and the excretion of urinary coproporphyrin in a number of subjects, the possibility that impaired haem synthesis in the sideroblastic anaemias is associated with abnormal vitamin B6 metabolism at the level of the mitochondrion must still be considered.

Adolescent↗
PubMed1979

Vitamin B6 metabolism in anaemic and alcoholic man.

Physiological and pathological factors affecting intracellular red cell vitamin B6 metabolism in normal, anaemic and alcoholic man were studied using a new assay for pyridoxine kinase (PnK) together with saturated and total aspartate aminotransferase (EGOT) activities as indirect indices of intracellular pyridoxal 5-phosphate (PLP) availability. In studies of anaemic states, subjects with iron deficiency anaemia demonstrated elevated levels of both PnK and saturated EGOT, while seven out of 17 subjects with inflammatory anaemia had subnormal PnK but variable saturated EGOT activities. Despite a high incidence of complicating inflammatory disease, alcoholic subjects with or without ring sideroblastic anaemia had elevated levels of both PnK and saturated EGOT. As judged from the saturated EGOT and the ratio unsaturated EGOT/saturated EGOT, intracellular PLP availability was always appropriate to the higher levels of PnK activity.

Alcoholism↗
PubMed1978

Vitamin B6 metabolism in human red cells. I. Variations in normal subjects.

Physiologic and pharmacologic factors affecting intracellular red cell vitamin B6 metabolism in normal human subjects were studied using a new assay for pyridoxine kinase (PnK) together with saturated and total aspartate aminotransferase (AST) activities as indirect indices of intracellular pyridoxal 5-phosphate (PLP) availability. The presence of reduced PnK activity in Blacks was confirmed but this could not be explained on the basis of increased enzyme inactivation during red cell aging in vivo. Racial differences were also noted in the metabolism of AST and, in Caucasians, net dissociation of PLP from the apoprotein was demonstrated to occur in vivo. Despite the wide variation in Pn5 activity, AST levels were maintained within relatively narrow limits. However, when pharmacologic doses of pyridoxine were administered, PnK and AST activities increased proportionately. These findings suggest that when the supply of B6 vitamers is not limiting, PnK may play a role in regulating red cell PLP levels.

Asian People↗
PubMed1978

Controlled trial of methotrexate and Bacillus Calmette-Guérin therapy for advanced head and neck cancer.

Thirty-eight patients with advanced, inoperable squamous cell carcinoma of the head and neck were randomized to receive methotrexate alone or methotrexate with Bacillus Calmette-Guérin. The response rates with methotrexate (3 of 19) and methotrexate plus B. Calmette-Guérin (4 of 16) were similar, as was the duration of response and survival of the two groups. The results of in vitro immunological studies of lymphocytes were assessed. Marked weight loss, poor performance status, and distant metastases were the most important prognostic factors. The presence of anergy was significantly correlated with weight loss. This study also indicated that a large tumor burden is a frequent occurrence in advanced head and neck cancer and may account for the lack of efficacy of B. Calmette-Guérin.

B-Lymphocytes↗
PubMed1977

Effect of calcitonin treatment on deafness due to Paget's disease of bone.

Seventeen patients with Paget's disease of the skull and deafness were followed for nine to 18 months. Patients who received calcitonin treatment showed less deterioration in hearing than untreated patients. Calcitonin treatment may retard the progression of deafness in Paget's disease, and further studies are indicated.

Aged↗
PubMed1971

Pseudouridylate synthetase of Escherichia coli: a catabolite-repressible enzyme.

The growth on pseudouridine of two pyrimidine auxotrophs of Escherichia coli (Bu(-) and W63-86) was markedly enhanced when glycerol replaced glucose as a carbon source or when adenosine 3':5'-cyclic monophosphoric acid was added to medium containing glucose. These results indicated that an enzyme catalyzing a reaction in the pathway of pseudouridine conversion to uracil was sensitive to catabolite repression. The following pathway is proposed for pseudouridine utilization: [Formula: see text] [Formula: see text] Pseudouridylate synthetase was sensitive to catabolite repression in strains Bu(-) and W63-86. In contrast, strains B5RU and W5RU, mutants of Bu(-) and W63-86 which were selected for their ability to grow rapidly on pseudouridine in the presence of glucose, had high levels of pseudouridylate synthetase in the presence of glucose. In the case of B5RU but not W5RU, synthetase activity was greater in cells grown on glycerol or on glucose plus adenosine 3':5-cyclic monophosphoric acid than on glucose.

Carbon Isotopes↗