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Biomedical subjects

R A Nelson

Publications and source records attributed to R A Nelson.

At least 109 records · Page 6Linked to original sources
PubMed1980

Ocular toxicity in beagle dogs with an experimental fluoromethane-sulfonanilide sympathomimetic agent.

ocular lesions were detected in Beagle dogs receiving high doses of BA6650, an experimental fluoremethane-sulfonanilide sympathomimetic agent, during a preclinical safety evaluation study. The oral dose of BA6650 was increased during the 14-day study from 20 mg/kg twice daily (bid) for days 1-3 to 30 mg/kg bid for days 4-6 and finally to 40 mg/kg bid for days 7-14. Two males and two females received BA6650 while one male and one female were not dosed. Intraocular pressure in the untreated controls fluctuated during the study between 17 and 22 mmHg. Intraocular pressure decreased in 3 of 4 BA6650 treated dogs from an initial mean value of 17 to a final mean value of 8 mmHg. Ocular lesions consisting of conjunctival hyperemia, corneal opacities, epiphora, mydriasis followed by miosis, corneal herniation, hypopyon, ptosis, and anterior synechia developed in three of the animals.

Animals↗
PubMed1980

Appearance of D-alloisoleucine in the blood plasma of laying hens.

Two strains of laying chickens were used to investigate the effects of amino acid additions, including D-alloisoleucine, to a low protein corn-soy diet on plasma free amino acids and egg albumen amino acid composition. Intake of .1% D-alloisoleucine with the L-form in the mixture resulted in appearance of this compound in the plasma but not in egg albumen. The concentration of plasma valine was significantly increased when the amino acid (.2% D-L) was added to the 10% protein diet. Threonine and arginine additions did not increase the concentration of the respective amino acid in the plasma significantly. The amino acid composition of egg albumen remained unaffected by dietary supplementation. Production data along with amino acid composition of egg albumen showed that the laying hen reduces production rather than altering amino acid composition of egg albumen protein in its response to reduced uptake. No apparent strain differences were noted.

Animal Feed↗
PubMed1980

Protein and fat metabolism in hibernating bears.

Hibernation in the bear (Ursus americanus) is unique in that it is continuous for 3 to 7 months and occurs at near normal body temperature, yet the bear does not eat, drink, urinate, or defecate. During hibernation there is no loss of lean body mass because amino acids enter protein synthetic pathways at increased rates producing reciprocal decreases in entry into the urea cycle. The urea that is formed is hydrolyzed and the nitrogen released is combined with glycerol to form amino acids, which reenter protein synthetic pathways. Body fat supplies the substrate for metabolism (400 kilocalories/day). Ketosis does not occur. Metabolic water is sufficient to maintain normal hydration. About 100 ml of urine is filtered daily by the kidneys but the baldder wall transports water and solute back into blood at a rate about equal to their entry into the bladder. The bear cannot duplicate its winter adaptation in summer when housed in the cold and dark. During hibernation the bear shows hypothalamic hypothyroidism and increased testosterone production. These changes appear necessary for developing the selective states of anabolism and catabolism found in the hibernating bear.

Animals↗
PubMed1979

Effect of winter sleep on pituitary-thyroid axis in American black bear.

During winter sleep the black bear has decreased levels of serum total and free thyroxine (T4) and triiodothyronine (T3) and a prolonged, delayed response of serum thyrotropin (TSH) (bioassay) to thyrotropin-releasing hormone (TRH). Four weeks after the end of winter sleep, levels of serum thyroid hormones increase, and TSH response to TRH is short and brisk. Serum T4 and T3 rise after TRH administration both during and after winter sleep; however, the maximum increment in serum T3 is greater during winter sleep when the TSH rise is also prolonged and exaggerated. These observations suggest that transient hypothyroidism of possible hypothalamic origin occurs in bears during winter sleep.

Animals↗
PubMed1979

Stapes surgery at the Otologic Medical Group.

We reviewed the records of 498 primary stapedectomy cases in regard to duration of disease, age at surgery, oval window pathology, hearing results, dizziness, and tinnitus. Ninety percent of the cases in which a tissue graft had been used as an oval window covering obtained a postoperative hearing level within 10 dB of the preoperative bone conduction. Postoperative sensorineural hearing impairment occurred infrequently and was two to three times more common in cases in which Gelfoam had been used as an oval window covering as compared to tissue grafts. Postoperative dizziness of one degree or another persisted at four months in 2 percent of the cases and was a problem for the patient in two cases (0.4%). This dizziness was likewise more common in Gelfoam cases. We concluded that tissue grafts are a better covering for the oval window than Gelfoam both in regard to hearing improvement and lack of postoperative complications.

Adult↗
PubMed1978

High fiber diet in hyperlipemia. Comparison with cholestyramine treatment in type IIA hyperlipoproteinemia.

Fourteen patients with type IIa hyperlipoproteinemia were treated with a high fiber intake (powdered cellulose or soy hulls or both) for six months. Eight of the patients were treated with 16 g of cholestyramine resin daily without the high fiber intake for an additional six months. The cholesterol intake was comparable in both treatment programs. The mean serum cholesterol levels decreased during both, but the decrease occurred and was more pronounced in all patients treated with cholestyramine. Responsiveness to the high fiber diet was not related to an increased responsiveness to cholestyramine treatment. In most patients the serum triglyceride levels increased, and the fasting plasma glucose level did not change substantially during either treatment program. Both regimens were free of adverse side effects.

Adult↗
PubMed1978

Combined deficiency of glucose-6-phosphatase and fructose-1, 6-diphosphatase. Studies of glucagon secretion and fuel utilization.

An adult woman with hypoglycemia, hyperlactatemia, hyperuricemia, hypertriglyceridemia, hyperketonemia and inability to make new glucose from galactose, fructose, glycerol and alanine was found to have no hepatic glucose-6-phosphatase and deficient fructose-1,6-diphosphatase. Nonautonomous hyperglucagonemia was demonstrated and shown to contribute to the hyperlactatemia and hyperketonemia. A paradoxic hyperlactatemic response to glucose and galactose was observed. Studies of substrate utilization showed prompt adaptation to changes in dietary supply of energy which probably accounted for her never having experienced symptoms of hypoglycemia.

Adult↗
PubMed1977

Sucrose sensitivity of patients with coronary artery disease.

Various loads of simple carbohydrates were fed to 148 patients with known coronary-artery disease (CAD) for 4 days in the Clinical Research Center. The 148 patients were grouped according to the diet regimen tested-sucrose (low and high), glucose, and fructose. A high-sucrose diet was fed to 29 control subjects. Diets containing 2 g of simple carbohydrate (predominantly either sucrose or glucose) per kilogram of body weight per day had no significant effect on fasting plasma glucose, serum triglycerides, or serum free fatty acids. However, diets containing 4 g of simple carbohydrate (predominantly sucrose) or 2 g fructose per kilogram of body weight per day produced a significant rise in serum triglycerides with decreases in fasting plasma glucose and free fatty acids. Serum cholesterol diminished in all the diet groups, probably because of the decrease fat and cholesterol intakes. The increase of serum triglycerides in CAD patients receiving simple carbohydrate at the 4-g/kg rate was significantly greater than in the normal control subjects fed the same diet, suggesting a sensitivity of CAD patients to this stimulus. No significant correlation could be demonstrated between changes in serum triglycerides and the extent of CAD (one, two, or three vessels) as determined from coronary angiograms.

Adult↗
PubMed1977

Morphogenesis of bacteriophage phi 29 of Bacillus subtilis: mapping and functional analysis of the head fiber gene.

A set of mutants of Bacillus subtilis bacteriophage phi29 unable to synthesize the head fiber protein has been identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography. Infectious phage are produced during restrictive infection. We have focused on mutant sus 8.5(900) because the mutation is suppressible by both the su(+3) and su(+44) hosts, and it can be mapped by three- and four-factor crosses. After restrictive infection with mutant sus 8.5(900), a fragment about 70% of the size of the normal fiber is produced as well as particles that are fast-sedimenting in sucrose gradients relative to phi29(+). These particles have the buoyant density of particles with the fibers removed and have the absolute plating efficiency of phi29(+). Fiber protein is absent from prohead as well as virion. A second set of mutants produces fiber protein with a slightly altered electrophoretic mobility. This type of fiber protein is either present or absent on both prohead and virion. A third class of mutants, typified by 914, produces a "normal" fiber, but a major head protein of altered electrophoretic mobility. After infection by this mutant, the fiber is absent from both prohead and virion, and the biological and physical properties of the 914(-) particle are similar to those of particles produced after infection of the su(-) host by sus8.5(900). These observations suggest that the head fiber is not an essential component of the prohead or virion and that the assembly process is efficient in the absence of fiber protein. Three- and four-factor genetic crosses have established the order sus8(769)-8(914)-sus8.5(900)-sus9(756) and indicate that cistrons 8 and 8.5 code for the major head protein and head fiber protein, respectively.

Bacillus subtilis↗
PubMed1976

Comparison of serum cholesterol in children fed high, moderate, or low cholesterol milk diets during neonatal period.

The long-term effects of milk diets in infancy on the blood serum cholesterol concentrations were studied in 97 school children 7-12 yr of age. Detailed histories were available for these children with respect to their diets during infancy. The major criterion for inclusion in the study was milk (human milk, cow's milk, or commercial formula) as the exclusive source of diet cholesterol during the first 3 mo of life. Fasting blood cholesterol and triglycerides were measured in these 97 school children, and the current diets of 29 of the 97 were evaluated for daily cholesterol intake. A 7-day diet diary was recorded, the food intake was measured and analyzed for nutrients, and validity of the diets was verified by determination of urinary nitrogen excretion. Results of the study showed that the school children fed a low cholesterol formula during infancy had a mean serum cholesterol value 7-12 yr later that was lower than the mean values of the groups fed greater amounts of cholesterol in infancy. Analysis of current diets of 29 of the 97 school children showed that their current dietary intake of cholesterol was low. Dietary intake of cholesterol did not have a noticeable effect on the serum cholesterol levels of the 29 children.

Animals↗