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Biomedical subjects

R G Brown

Publications and source records attributed to R G Brown.

At least 145 records · Page 8Linked to original sources
PubMed1976

Alaskan malamute chondrodysplasia. I. Bone composition studies.

Chondrodysplastic Alaskan Malamutes exhibit concentrations of calcium, phosphorus and magnesium in radius, ulna, and humerus bone segments similar to those of non-chondrodysplastic dogs of similar age. Significant differences in extractability of mineral components with 5% EDTA were observed in specific bone segments. Although these data suggest that a primary derangement in calcium and phosphorus was possible the magnitude of the differences strongly suggested it unlikely and stress or mechanical factors may account for some of the observed differences. The possibility that chondrodysplasia provides a model for human disorders such as fibrogenesis imperfecta ossium was discussed. These data presented support a previous hypothesis that the chondrodysplasia is not a vitamin D-resistant rickets syndrome.

Analysis of Variance↗
PubMed1976

Alaskan malamute chondrodysplasia. II. Urinary excretion of hydroxyproline, uronic acid and acid mucopolysaccharides.

The urinary excretion of free, total and non-dialyzable hydroxyproline appeared to be similar in both chondrodysplastic and non-chondrodysplastic Alaskan Malamutes of ages six and twenty-six weeks suggesting the metabolic defect was probably not related to a gross disturbance in collagen metabolism. Urinary hexuronic acids also appeared to be similar in levels for both populations. A four-fold increase in urinary mucopolysaccharide levels observed at age twenty-six weeks in the chondrodysplastic Alaskan Malamute suggested a deviation from normal. The magnitude and variability of deviation were not sufficient to indicate that this condition could serve as a model for the mucopolysaccharidosis of man but probably indicated a delayed maturation process.

Animals↗
PubMed1975

Characterization of two reserve glucans from Clostridium pasteurianum.

The reserve glucans of C. pasteurianum, previously assumed to be a single polysaccharide, have been fractionated into two polysaccharides which resemble amylopectin and dextran. Both polysaccharides are produced when cells are grown with sucrose, D-glucose, or D-fructose as carbon sources.

Amylopectin↗
PubMed1975

Intestinal calcium-binding protein in animals fed normal and rachitogenic diets: II. Pig studies.

Experiments were carried out in pigs to investigate the relationship between concentration of intestinal calcium-binding protein (CaBP) and the presence of rickets. Pigs made rachitic by a diet deficient in calcium and in vitamin D had concentrations of intestinal CaBP no less than values obtained on control pigs. These experiments, together with earlier work on rats (Can. J. Physiol. Pharmacol. 1975. 53, 137--143), demonstrate a poor inverse correlation between levels of intestinal CaBP and rickets.

Animals↗
PubMed1975

A study of thyroid activity in dwarf and non-dwarf female chicks during key physiological states of growth and reproduction.

Thyroid function, as indicated by the maximum percent uptake of iodine-131, was measured in non-dwarf and recessive, sex-linked dwarf White Leghorn female chickens at different ages. The rate of uptake and release of 131-I by the thyroid gland was closely monitored over a period of eight days after the injection of the isotope. No significant differences were observed in thyroid uptake value of dwarf chicks in one-week-old group (approximately equal to 11.5 per cent for each group). At the age of four weeks the maximum uptake was only 5.58 per cent in dwarfs compared to 10.11 per cent in non-dwarf chicks. Potassium thiocyanate treatment caused a significant reduction in the uptake of iodine-131 by the thyroid glands of both 4-week-old dwarf and non-dwarf chicks although there was no difference in the response pattern of either group to the treatment. Dwarf laying-hens had a significantly lower maximum thyroid uptake (1.4 per cent) when compared to non-dwarf laying hens (2.48 per cent). A consistantly slower rate of uptake by the thyroid glands of dwarf chickens was observed for all age groups than equivalent non-dwarfs but there were no apparent differences in the release rates of 131-I by dwarfs when compared to non-dwarfs. No significant differences were observed between the 131-I uptake by the ovaries or eggs of both dwarf and non-dwarf laying hens. A gradual decrease in thyroid activity was observed in both dwarf and non-dwarf chickens with increased age. From this study it was evident that the dwarf bird had significantly lower thyroid activity but with normal organification. The defect in thyroid function in the dwarf bird apparently was not at the level of synthesis but at the level of uptake of iodine.

Age Factors↗
PubMed1975

Alleviating mortality associated with a vitamin E-selenium deficiency by dietary ascorbic acid.

Adding ascorbic acid to a practical ration deficient in vitamin E and selenium for the growing duck substantially reduced associated mortality. The continued appearance of various myopathies but absence of vascular faults supported implication of a reduced de novo ascorbate synthesis as part of the syndrome. Presumably, alleviation of this induced secondary inadequacy with its more lethal pathology was the primary reason for the lower death rate.

Animal Feed↗
PubMed1975

Thyroid metabolism in the recessive sex-linked dwarf female chicken. 1. Age related changes in thyroid hormone synthesis and circulating thyroid hormone levels.

Age related changes in the levels of circulating thyroid hormones as well as the type of hormones synthesized in the thyroid glands from normal and sex-linked recessive dwarf, female chickens were studied. The impact of the presence of the dwarf gene on the parameters measured was minimal but significant alterations in the types of hormones produced in the thyroid gland with increasing age were observed. As the birds approached sexual maturity, the synthesis of triiodothyronine increased sharply such that the ratio of triiodothyronine (T3): tetraiodothyronine (T4) was approximately 15:1. This was in contrast to the T3:T4 ratio of younger birds which was approximately 0.7:1.0. This shift in hormone synthesis was reflected in relatively more circulating T3 in laying hens when compared with younger birds. It was also noted that four week old dwarf birds had higher circulating T3 values than those found for the normals.

Age Factors↗
PubMed1975

Thyroid metabolism in the recessive sex-linked dwarf female chicken. 2. Binding of thyroid hormones by serum proteins.

Serum protein profiles were studied together with serum binding sites and capacity for L-thyroxine in dwarf and non-dwarf White Leghorn and White Rock breeds at ages 1 wk., 4 wks. and in laying hens. Serum protein profiles varied with breed, strain and age. The percent gamma-globulin fraction was greater (P less than .05) in dwarf 1 wk. old and laying hens of the White Leghorn breed when compared with the normals. The only difference found in the White Rock breed was a decreased level of albumin in dwarf laying hens. There were no significant differences in the capacity or sites of binding of L-thyroxine to serum proteins although greater amounts of L-thyroxine were bound to globulin fractions in the dwarf. The data were interpreted to suggest that changes in serum protein profiles may have been the result of hypothyroidism at the cellular level but there was no reason to suspect abnormal binding of thyroid hormones to be the cause of that hypothyroidism.

Animals↗
PubMed1975

Thyroid metabolism in the recessive sex-linked dwarf female chicken. 4. The influence of exogenous thyroid hormones on amino acid uptake by plasma and tissues.

The influence of exogenous triiodothyronine (T3) or tetraiodothyronine (T4) on the incorporation of 3H-labelled methionine, alanine and lysine into plasma, liver and kidney was studied in 4 wk. old dwarf and non-dwarf female, White Leghorn chickens. The response to exogenous T3 or T4 of the birds was directly dependent on the dwarf status as well as the tissue and/or amino acid studied. In general, there was a decreased amino acid uptake by dwarfs and T3 and/or T4 depressed amino acid uptake in all combinations studied except for the uptake of lysine by the kidney of the dwarf. In that tissue, T4 administration caused a significant increase in lysine incorporation. The results found probably were due to different tissue amino compositions or rates of synthesis of proteins by dwarf birds when compared to normals and a differential sensitivity of dwarf birds to changed T3/T4 ratios.

Alanine↗
PubMed1975

Thyroid metabolism in the recessive sex-linked dwarf female chicken. 5. Effects of exogenous thyroid hormones on amino acid uptake by eggs.

The incorporation of L-methionine-3H(G) and L-lysine-4,5'3H(n) into egg albumen by dwarf and non-dwarf White Leghorn hens was studied together with the influence of exogenous triiodothyronine (T3) and tetraiodothyronine (T4) on those incorporation patterns. The results were influenced by the amino acid studied and by the strain of bird. The maximum uptake of methionine was a day 1 for the normal and at day 4 for the dwarf which suggested that the dwarf was storing methionine in the tissue first before incorporation into albumen. If the birds were given T3 the maximum for the normal was at day 1 and day 3 for the dwarfs. When T4 was given the maximum uptake was found at day 5 for normals, and at day 2 for dwarfs. In the dwarf, T4 administration essentially corrected the decreased rate uptake of methionine but markedly retarded its uptake by the normal birds. The results for lysine were quite different. The maximum uptake was on day 4 in control, day 3 for T3-treated and day 1 for T4-treated, normal birds. In dwarf birds, the maximum was at day 2 for the control and T4-treated, and day 4 for T3-treated groups. The data were interpreted to suggest strain differences in amino acid uptake patterns due to different rates of synthesis or composition of egg albumen and marked differences in response or recptor sites to thyroid hormones.

Amino Acids↗
PubMed1975

Transverse abdominal flaps and the deep epigastric arcade.

Further experience with the transverse abdominal flap, based on the deep epigastric arcade, is described. This flap is a logical extension of the concept of the deltopectoral flap (based on the internal mammary). The transverse abdominal flap derives its blood supply from the perforating branches of the deep epigastric arcade, and it can be used without a delay procedure when so constructed.

Abdomen↗