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Biomedical subjects

S H Allen

Publications and source records attributed to S H Allen.

At least 55 records · Page 3Linked to original sources
PubMed1978

A comparison of the malate dehydrogenase of the propionic acid bacteria with the mammalian soluble and mitochondrial isoenzymes.

1. Like the malate dehydrogenases of eucaryotic cells, the Propionibacterium shermanii enzyme is a dimer consisting of two 35,000 molecular weight subunits. 2. In electrophoretic behavior, resistance to substrate inhibition and stability to heating and dilution the P. shermanii MDH is more similar to the s-MDH than to the m-MDH of pig heart. 3. The P. shermanii MDH has a high turnover number (ca. 140,000) as well as Km values for both L-malate and oxalacetate which are four times higher than the mammalian isoenzymes. 4. A coupled assay for MDH using the malate-lactate transhydrogenase and diaphorase is described in which both substrates, L-malate and NAD, are regenerated.

Animals↗
PubMed1978

Conformational prediction and circular dichroism studies on ribosomal protein S4 from Escherichia coli.

The conformation of ribosomal protein S4 from Escherichia coli has been studied by circular dichroism (CD) and shown to possess unique conformation free in solution. The near ultraviolet spectrum suggests the existence of unique tertiary structural environment for the aromatic amino acid residues. The far ultraviolet spectrum gives an estimation of its secondary structure which is 32% alpha-helix and 14% beta-structure in reconstitution buffer at 25 degrees C. The conformation of S4 has been predicted from its sequence, and two models are presented here. An attempt is made to correlate these two molecular models with the available physicochemical data concerning the shape, conformation, and possible RNA binding site of protein S4.

Bacterial Proteins↗
PubMed1975

An abnormality of the bone marrow associated with vitamin E deficiency in sheep.

1. Sheep fed on a maintenance ration of wheaten-hay chaff or of wheaten-hay chaff-lucerne-hay chaff (I : I, W/W) became deficient or incipiently deficient in vitamin E. 2. Degenerative changes were observed in bone marrow and muscle, and liver function was imparied in some animals. These abnormalities were not influenced by the vitamin B12 status of the animals or by a shortage of cobalt in the rumen. 3. Plasma ascorbic acid levels may not have been optimum, and folic may not have been fully utilized by some sheep. 4. Liver function responded faily rapidly to alpha-tocopheryl acetate, but skeletal muscle had not returned to normal after 28 weeks of treatment. A variable trend towards normal cellularity was found in bone marrow following supplementation with alpha-tocopheryl acetate. 5. A secondary deficiency or, alternatively, inefficient excretion or metabolism of a toxic material, may occur in vitamin E deficiency as a result of degenerative changes in the absorptive or excretory areas of the intestinal tract and be responsible for the bone marrow abnormality.

Animal Feed↗
PubMed1975

Fitting Richards' Curve to data of diverse origins.

Published techniques for fitting data to nonlinear growth curves are briefly reviewed; most techniques require knowledge of the shape of the curve. A flexible growth curve developed by Richards (1959) is discussed as an alternative when the shape is unknown. The shape of this curve is governed by a specific parameter, which can be estimated from the data. We describe in detail the fitting of a diverse set of longitudinal and cross-sectional data to Richards' growth curve for the purpose of determining the age of red fox (Vulpes vulpes) pups on the basis of right hind foot length. The fitted curve is found suitable for pups less than approximately 80 days old. The curve is extrapolated to pre-natal growth and shown to be appropriate only for about 10 days prior to birth.

Age Factors↗
PubMed1970

Factors affecting formiminoglutamic acid excretion in vitamin B 12 deficiency.

1. Formiminoglutamic acid, a product of the catabolism of histidine, is excreted in abnormally large amounts in the urines of vitamin B(12)-deficient rats and of vitamin B(12)-deficient sheep; the excretion is reduced to negligible amounts after administration of vitamin B(12). 2. After administration of certain methyl donors to vitamin B(12)-deficient rats or sheep urinary excretion of formiminoglutamic acid is temporarily decreased. 3. Irrespective of the pteroylglutamic acid status of the animals neither vitamin B(12)-deficient rats nor vitamin B(12)-deficient sheep have the ability to deal efficiently with histidine. 4. In sheep, urinary excretion of formiminoglutamic acid is increased after administration of aminopterin; treatment with pteroylglutamic acid restores the ability of the animal to deal with the catabolic products of histidine. 5. The possible functions of vitamin B(12) and methionine in relieving a virtual deficiency of pteroylglutamic acid are discussed.

Aminopterin↗