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Biomedical subjects

P Griminger

Publications and source records attributed to P Griminger.

At least 19 recordsLinked to original sources
PubMed1990

Endocrine-nutrition interactions in birds.

This review will discuss the uses of avian models, particularly the chicken, to examine nutrition-endocrine interactions. The chicken has been employed extensively to examine nutritional effects. The effects of fasting, protein deficiency and calcium deficiency on endocrine status have been the subject of intense investigation in young chicks and adult female chickens. The ratio of circulating concentrations of triiodothyronine (T3) and thyroxine (T4) is substantially changed by fasting or protein deficiency. Similarly, protein deficiency reduces circulating concentrations of insulin-like growth factor I (IGFI) while protein deficiency increases growth hormone (GH). Moreover, protein deficiency increases the sensitivity and responsiveness of adrenocortical cells. The chicken also as advantages for studying diabetes, endocrine pancreatic functioning due to the splenic lobe of the pancreas being predominantly endocrine in nature, and the cellular mechanism of GH on chicken adipose tissue. The adult female chicken with its high calcium requirement is a unique system for examining nutritional effects on reproduction.

Adipose Tissue↗
PubMed1987

Control of energy balance during egg production in the laying hen.

The energetic costs of egg production are considered, as is the relationship between egg production and feed intake. Hens feed during the photophase with a peak in consumption prior to the scotophase. This pattern of intake, followed by nocturnal fast, would be expected to lead to an energy deficit at night. However, much of the energy requirement of the night is met by utilization of feed stored in the upper gastrointestinal tract. It is presumed that some nocturnal energy deficit occurs and is met by changes in metabolism and endocrine balance. The hormonal involvement in these changes in avian metabolism is discussed.

Animal Feed↗
PubMed1986

The effect of dried and fresh eggs on plasma cholesterol and atherosclerosis in chickens.

Oxidation products of cholesterol, which have been observed to be formed in powdered eggs and other dehydrated cholesterol-containing foods, have been suspected as the probable primary cause of atherosclerotic lesions. The feeding of powdered vs. fresh egg yolks to young male chickens up to 30 and 43 weeks of age, respectively, produced approximately the same increase in plasma cholesterol, liver fat, and liver cholesterol when compared to the feeding of a soybean-based cholesterol-free diet. Aortic atherosclerosis, however, was found to be more severe in a group of birds fed fresh egg yolks than in those fed powdered egg or the cholesterol-free diet. A previously demonstrated, enhanced feedback inhibition of cholesterol synthesis by oxidized cholesterol derivatives may at least partly explain these results.

Animals↗
PubMed1985

Nitrogen balance studies in aging rats.

Nitrogen balance studies were conducted to compare the protein requirements of aged (24-month-old) and mature (12-month-old) rats for possible age-related differences. Four diets with protein supplied as amino acid mixtures simulating casein protein at 4.5%, 4.5% plus 1.5% indispensable amino acids of casein, 4.5% plus 1.5% dispensable amino acids of casein or 6.0% casein protein were offered for one week each during a four-week counter-balanced dietary sequence. Lower food and nitrogen intake of aged rats resulted in a lower mean nitrogen balance compared to that of the mature animals. Calculations of the level of N intake necessary to provide for N equilibrium in the aged rats indicated an apparent increase in the actual net need for nitrogen and indispensable amino acids when compared with the needs of the mature animals.

Age Factors↗
PubMed1984

Improvement of nitrogen retention by arginine and glycine supplementation and its relation to collagen synthesis in traumatized mature and aged rats.

The effect of arginine and glycine supplementation on reducing body protein losses and on enhancing wound healing after trauma was studied in two age groups. Mature (4 month) and aged (24 month) Fischer 344 male rats were fed a diet containing 25% casein and 0.4% methionine with or without supplementation with 2.4% arginine . HCl and 1.0% glycine for 7 days before and after laparotomy. Nitrogen (N) balance studies (N intake - urinary N) were carried out during the last three pretrauma days and seven posttrauma days. The supplemented rats retained significantly more N than the controls and the mature rats significantly more than the aged rats. Polyvinyl alcohol sponges, implanted during surgery and removed from the rats on day 3 or 7 after surgery, were analyzed for hydroxyproline content and for the ratios of type III/type I collagen synthesized. Sponges obtained from the supplemented and the mature rats had more hydroxyproline and higher ratios of type III/type I collagen than those from the control and the aged rats. The beneficial effect of arginine and glycine supplementation on improving N retention in traumatized rats appears to be due, at least in part, to increased collagen synthesis in wounds.

Aging↗
PubMed1983

Long-term effects of activity and of calcium and phosphorus intake on bones and kidneys of female rats.

Over a 22-week period, young female rats in conventional cages gained significantly more weight than rats housed with free access to running wheels. A trend toward increased bone density was indicated in runners. In a second test, young female rats were housed under the same conditions for 30 weeks, but the active group was then forced to run in a treadmill for 30 minutes, 5 times a week, over a 43-week period. During this time rats were fed either diets providing adequate Ca (0.5%) and adequate P (0.4%) or high P (1.2%), or low Ca (0.3%) and high P (1.2%). Running appeared to benefit long bone density but could not completely compensate for a high P or a low Ca, high P intake. A bone that received only indirect stress during exercise (atlas) was not significantly affected by running. However, a high P diet significantly decreased atlas bone density, while the negative effect of this diet on the density of long bones was at a lower level of significance. A low Ca, high P diet clearly decreased bone density in all bones investigated. Running had no effect on kidney mineralization, but either a high P or low Ca, high P diet greatly increased the concentration of these minerals in the kidney.

Animals↗
PubMed1982

Effects of gradation in protein-calorie restriction on the hypothalo-pituitary-gonadal axis in young domestic fowl.

The effect of protein-calorie restriction on the circulating concentration of luteinizing hormone (LH) was investigated in the young domestic fowl. Two-week-old broiler chicks were fed isocaloric synthetic diets with varying levels of soy protein for a period of 14 days. Growth rate, as indicated by body weight, was decreased as the level of protein in the diet was reduced. Body weights of birds on a 3% protein diet were only 29.7% that of birds on a 24% protein diet. Severe protein-calorie restriction was also associated with depressed plasma LH levels in birds of both sexes, with male birds appearing to be more sensitive to this deficiency. A reduction of protein in the diet from 24% to 3% was associated with a 69% decrease in LH in males and a 43% decrease in females. In addition to lower circulating concentrations of LH, protein-calorie restriction was associated with a reduction in gonadal weight. Testes weights in birds on a 3% protein diet were only 16% of those on a 24% protein diet. Studies with synthetic luteinizing hormone releasing hormone (LHRH) indicated that protein-calorie restriction alters luteinizing hormone secretion via a hypothalamic effect.

Animals↗
PubMed1980

Effect of dietary carbohydrates and biotin level on cecal size and biotin concentration of growing chickens.

Growing chickens were fed three levels of biotin, 0, 20, and 100 micrograms/kg diet, and four different carbohydrates, glucose, dextrin, sucrose, and sorbitol, in order to study the effect of dietary carbohydrates on the level of cecal biotin. Dietary sorbitol was found to enhance the concentration of cecal biotin at suboptimal levels of dietary biotin, while dietary dextrin had the opposite effect. When the dietary requirement of biotin was met, cecal biotin greatly increased in the presence of dietary glucose, sorbitol, and sucrose but remained at a low level when dextrin was the dietary carbohydrate. Dietary sorbitol increased significantly the dry weight of ceca over those of birds fed other carbohydrates.

Animals↗
PubMed1977

Amino acid maintenance requirements of young women and of adult rats fed different dietary amino acid patterns.

Adult rats were fed isonitrogenous diets (5% protein equivalent) providing indispensable amino acids either in the whole-egg protein pattern or in the adult rat maintenance pattern of Smith and Johnson (S & J. Brit. J. Nutr. 21:17, 1967). In two separate experiments the threonine and the methionine (total sulfur amino acid) requirements were assessed. Similar responses were obtained with rats on the threonine experiment independent of the pattern of indispensable amino acids fed. In the methionine experiment the rats fed the S & J pattern showed a lower need for this amino acid than the rats fed the egg pattern. When the latter group was switched to the S & J pattern, they too required less methionine. In the experiment with college students (female) fed 7 g of nitrogen/subject per day, the lysine requirement on the whole-egg pattern was compared to the requirement on a pattern equal to twice the previously published requirements for young women. No evidence was obtained over the relatively short experimental period that the lysine requirement differed substantially with change in the pattern of indispensable amino acids.

Adult↗
PubMed1976

Effect of dietary copper, manganese, and zinc on nitrogen equilibrium and mineral distribution subsequent to trauma in mature rats.

Following fracture of the femur, changes in nitrogen retention and mineral tissue concentrations in response to graded levels of dietary copper, manganese, and zinc were investigated. Retained nitrogen and liver copper, manganese, zinc, nitrogen and glycogen were determined prior to trauma and at 48-hour intervals for 8 days posttrauma. The excretion of nitrogen increased, and liver copper,manganese, and zinc decreased, as did liver nitrogen and glycogen in response to fracture. Increasing dietary copper, manganese, or zinc increased liver copper, manganese, or zinc, respectively, and decreased nitrogen loss by traumatized rats. The data suggest that trauma induced a change in the concentrations of liver copper, manganese, and zinc which coincided with changes in liver nitrogen and glycogen. The results indicated that subsequent to femoral fracture, the nutritional requirement for copper, manganese, and zinc for minimal nitrogen loss were higher than the NRC requirements for the mature male rat.

Animals↗