Biomedical subjects

R W Rosebrough

Publications and source records attributed to R W Rosebrough.

At least 55 records · Page 3Linked to original sources

PubMed1991

Cardiac catecholamine metabolism in copper-deficient rats.

After parturition, Sprague-Dawley dams were fed diets containing either 0.6 (-Cu) or 6 (+Cu) mg of copper/kg of diet. Pups were weaned either to the diet of their dam or to the diet fed to dams in the other treatment group in a crossover design. At 7 wk of age, Cu-deficient rats were characterized by low tissue Cu and an enlarged heart with increased levels of dopamine (DA) and decreased levels of norepinephrine (NE). These changes resulting from Cu deficiency were independent of gender. In vivo synthesis of cardiac NE from DA in Cu-adequate rats was significantly greater than in Cu-deficient rats. Turnover of cardiac NE was estimated from the temporal change in the specific activity of [3H]NE. Fractional turnover rates (percentage per hour) of cardiac NE were similar in both dietary groups, although the cardiac turnover of NE (nanograms per hour) was 1.4-fold higher in Cu-adequate rats than in Cu-deficient rats. Repletion of Cu-deficient rats with dietary Cu increased the total amount of cardiac NE to 78 and 93% of control values after 1 and 2 d, respectively. Significant changes in the quantities of NE and DA in the heart of rats whose intake of Cu was restricted from birth were first detected at 4 wk of age, but cardiac hypertrophy was not observed until 5 wk of age. The data support the proposal that the altered levels of DA and NE in the heart of Cu-deficient rats are primarily the result of decreased activity of DA-B-monooxygenase and demonstrate that Cu supplementation rapidly repletes cardiac NE in Cu-deficient rats. Moreover, changes in the concentrations of NE and DA in the heart precede and may contribute to the development of cardiac hypertrophy.

Animals↗

PubMed1991

Identification of circulating growth hormone-binding proteins in domestic poultry: an initial characterization.

Multiple growth hormone (GH)-binding proteins (GHBPs) were identified in serum and plasma samples from domestic chickens and turkeys. Proteins were separated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis on 10% acrylamide, 2.7% bis discontinuous gels under reducing conditions and electrotransferred to nitrocellulose paper. Western blots were incubated with 125I-labelled recombinant chicken GH (cGH) or bovine GH and GHBPs visualized by means of autoradiography. In fresh samples (less than 2 h from collection to gel electrophoresis), multiple minor high Mr bands were evident between approximately 72,000 and 175,000. Two major bands were observed at approximately 69,500 and 27,500. The latter is consistent with previous reports for the rat and mouse serum GHBPs based on nucleotide sequence analysis. The minor bands were essentially undetectable after storage at -25 degrees C for several months, and an additional major band at Mr approximately 52,500 appeared. The Mr-69,500 major protein contained N-linked carbohydrate, as determined by a reduction in molecular size by treatment with peptide N-glycosidase F. Binding of 125I-labelled GH was partially inhibited by co-incubation with 50 micrograms unlabelled pituitary-derived cGH/ml and excess unlabelled porcine GH as well as ovine prolactin, but not by bovine insulin. Non-specific binding of 125I-labelled GH by serum albumin was also observed. A comparison was made between these GHBPs and the hepatic GH receptor (e.g. molecular weight estimates, affinity for homologous versus heterologous GHs, cross-reactivity with prolactin, presence of N-linked carbohydrate). The origin and relationship among the various molecular weight species of GHBPs identified, and their potential role in regulation of the biological activity of GH in birds, remain to be determined.

Animals↗

PubMed1991

Influence of time of injection of recombinant porcine somatotropin (rpST) relative to time of feeding on growth performance, hormone and metabolite status, and muscle RNA, DNA, and protein in pigs.

Thirty-six barrows were used in a 2 X 3 factorial treatment array to determine the effects of time of injection (0800 [AM] or 1800 [PM]) of recombinant porcine somatotropin (rpST) (0, 50, or 100 micrograms.kg BW.d-1 adjusted weekly) relative to time of feeding on growth performance, carcass composition, serum hormones and metabolites, and muscle RNA, DNA, and protein. Pigs were fed at 85% of ad libitum and allowed access to feed between 0800 and 1200. Treatments were initiated at 38 kg and continued until each pig consumed an average of 7.5 Mcal of DE/d. There was no significant effect of injection time for any measure of growth performance or composition of gain even though rpST treatment improved most criteria evaluated. Treatment with rpST increased ADG by 30%, improved feed:gain by 23%, reduced lipid accretion by 46%, increased protein accretion by 69%, and increased loin eye area (LEA) by 26%. Time of injection also had no effect on serum hormones or metabolites, except for nonesterified fatty acids (NEFA), which were 20% higher in the AM-injected animals. Treatment with rpST increased (P less than .05) RNA concentration (21%) and RNA/DNA (17%) in longissimus dorsi (LD) muscle. In semimembranosus (SM) muscle, however, rpST administration resulted in an increased (P less than .05) DNA concentration (10%) and a decreased DM content (4%). These results suggest that rpST influences growth differently in these two muscles. We conclude that time of rpST administration (AM vs PM) has no effect on its metabolic properties and, therefore, no effect on growth performance in the pig.

Adipose Tissue↗

PubMed1991

Assessment of body composition of poultry by nuclear magnetic resonance imaging and spectroscopy.

Nuclear magnetic resonance (NMR) imaging and spectroscopy were used to assess body composition of the chicken and turkey poult. The NMR imaging was performed using a clinical, whole-body imaging system operating at 1.5 tesla (T; 63 MHz). Three-dimensional reconstruction of cross-sectional images made along the transaxial plane was used to estimate mass of the Pectoralis muscle of chickens ranging in weight from 140 to 2,760 g. Results indicate that NMR imaging can be used to determine size of the Pectoralis muscle (R2 = .99) in the bird, thus permitting repetitive measurements during the growth and development of the bird. The NMR spectroscopy was performed using an imaging spectrometer operating at 4.7 T (200 MHz). Integral areas of the water and lipid proton peaks of the spectra were compared with the water and lipid content of the whole body as determined by chemical analysis. Regression analysis of measurements made on turkey poults, ranging in weight from 115 to 630 g (n = 6), resulted in R2 values of .94 for NMR water proton peak area and total body water, .93 for NMR lipid proton peak area and total body lipid, and .96 for NMR water proton peak area and total body protein. From NMR spectroscopy of chickens weighing 528 +/- 18 g (n = 6), the relative area of the lipid peak correlated with whole-body lipid (R2 = .97). Thus, whole-body spectroscopy of smaller birds can be used to measure total body water, protein, and lipid content.

Animals↗

PubMed1990

Glucose production and glycogen cycle enzyme activities in avian liver explants: procedural optimization.

1. There are few studies which both describe the in vitro regulation of glycogen metabolism in nonmammalian animals and list methods to optimize assay conditions for these studies. 2. A mechanical tissue chopper was used to obtain 25-65 mg liver explants from 14- to 28-day old domestic turkeys to determine assay conditions (substrates, buffers, time), regulators (metals, salts and hormones) and points of endogenous regulation of glycogenolysis (protein phosphorylation and enzyme activity). 3. High- and low-bicarbonate-based buffers (Earle's balanced salts, EBSS and Hanks' balanced salts, HBSS, respectively) were used to determine buffer effects. 4. Glucose release into the incubation environment was greater in HBSS than EBSS. Adding HEPES to further buffer conditions did not change release rates. Adding bicarbonate to HBSS resulted in release rates similar to EBSS. 5. Calcium increased glycogenolysis in the presence of absence of equimolar concentrations of EGTA; potassium had no effect. 6. Porcine insulin (100 ng/ml) did not inhibit glycogenolysis; however, glucose release was increased by dibutyryl cyclic AMP. A noted catecholamine-induced increase in in vitro glycogenolysis and phosphorylase activity indicates that points of regulation are under phosphorylation-dephosphorylation regulation.

Animals↗

PubMed1990

Cardiac and splenic levels of norepinephrine and dopamine in copper deficient pigs and rats.

1. Copper deficiency decreased the concentration and content of norepinephrine in the hearts of pigs and rats. 2. Concentration, but not content, of norepinephrine was decreased in spleen of copper-deficient pigs, while splenic norepinephrine levels in rats were not altered by copper deficiency. 3. Cardiac and splenic concentrations and contents of dopamine were elevated in copper-deficient pigs and rats. 4. Tissue concentrations of catecholamines and the magnitude of change due to copper deficiency were greater in pigs than rats.

Animals↗

PubMed1990

Protein and energy relations in the broiler chicken. 8. Comparison involving protein- and lysine-adequate and inadequate diets on lipid metabolism.

Chickens were fed on diets containing either 12.8 MJ, 150 g crude protein (nitrogen x 6.25)/kg or 12.8 MJ, 200 g crude protein/kg to determine differences in metabolism. The diet containing 12.8 MJ, 150 g crude protein/kg contained either 8 or 12 g lysine/kg. Treatment variables examined in vitro were lipogenesis, glucose production and hepatic enzyme activities to compare metabolism in chicks fed on a low-protein, lysine-supplemented diet and a diet formulated to contain the required amount of lysine from intact protein. Growth was similar in chicks fed on diets containing either 12.8 MJ, 154 g crude protein with 12 g lysine/kg or 12.8 MJ, 200 g crude protein/kg. Net glucose production was greater (P less than 0.05) in liver explants from chickens fed on diets containing either 12.8 MJ, 154 g crude protein with 12 g lysine/kg or 12.8 MJ, 200 g crude protein/kg than in explants from chickens fed on 12.8 MJ, 150 g crude protein with 8 g lysine/kg. Pyruvate use for glucose production was greater (P less than 0.05) in chickens fed on a diet containing 12.8 MJ, 150 g crude protein with 8 g lysine/kg. The findings from the present study suggest that crystalline and 'natural' lysine additions to chick diets may influence metabolism differently.

Animals↗

PubMed1990

Dietary crude protein levels and the effect of isoproterenol on in vitro lipogenesis in the chicken.

Experiments were conducted with male broiler breeder chickens to determine the metabolic effects of two levels of dietary crude protein fed during a protein-reversal regimen on subsequent responses to a beta-adrenergic agonist (isoproterenol) in vitro. Day-old chickens were fed diets containing either 12 or 20% crude protein until 14 d of age and then switched to the opposite diet until 28 d. In experiment 1, chickens were killed at 28 d, and in experiment 2, at intervals following the switch at 14 d. In vitro lipogenesis and lipolysis were determined. The hepatic enzymes isocitrate dehydrogenase, malic enzyme and fatty acid synthetase were determined during the 14 to 28 d of age growth period. Both in vitro lipogenesis and lipolysis were greater at 28 d when chickens were fed the 12% rather than the 20% protein diet. Neither 0 to 14 d of age dietary treatment influenced 28-d metabolic parameters. In contrast, the 12% protein diet during the first 14-d period depressed body weight (160 g vs. 320 g; p less than 0.05) and weight gain during the 14 to 28 d of age period regardless of dietary crude protein levels (508 g vs. 626 g; p less than 0.05). Lipogenesis and lipolysis were at their highest points 4 d following the dietary switch. Isoproterenol decreased in vitro lipogenesis 70% in all dietary treatment groups. Stimulated lipolysis was not affected by nutritional status and was twice the unstimulated rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗

PubMed1990

Influence of dietary protein and recombinant porcine somatotropin administration in young pigs: growth, body composition and hormone status.

The influence of dietary protein and recombinant porcine somatotropin (rpST) administration on growth and body composition was investigated in barrows. Ten groups of six pigs starting at 30 kg were restrictively fed (approximately 80% of ad libitum) one of five diets containing 11, 15, 19, 23 or 27% protein. Diets contained skim milk (12%). Soybean meal diluted with cornstarch was used as the supplemental source of dietary protein. Diets were isocaloric (3.8 Mcal DE/kg) and all contained the same amount of lysine (18 to 20 g/kg). Thirty pigs were treated daily with rpST (100 micrograms/kg) by i.m. injection; the remaining pigs were treated with sterile diluent (control) for 42 d. Growth rate was greater in rpST-treated pigs at all levels of protein intake; however, the magnitude of the response to rpST treatment was lowest among pigs fed the diet containing 11% protein. Feed:gain ratio, backfat depth and carcass fat content were decreased in rpST-treated pigs compared to respective controls. Additionally, the concentration of carcass fat decreased concomitantly with an increase in dietary protein intake. Concentration of carcass protein increased linearly as dietary protein increased in control and rpST-treated pigs. In contrast, treatment with rpST was associated with an increased visceral mass; the concentration of protein and fat in the viscera was influenced by protein intake but not by rpST. These results, characterized by few treatment interactions, suggest that when energy intake is kept constant and appropriately fed pigs serve as controls, dietary protein and rpST influence growth and body composition by independent mechanisms.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗

PubMed1989

Protein and energy relations in the broiler chicken. Chronic or acute effects of alternating protein or intermittent feeding regimens on broiler lipid metabolism.

1. Broiler chickens growing from 7 to 28 d of age were given: (1) a 210 g protein/kg control diet for the entire experimental period, (2) an intermittent feeding regimen (210 g protein/kg diet for either 1 or 2 d followed by a 1 d fast), or (3) a daily change in the dietary protein level from 120 to 300 g/kg diet. Treatment variables examined were lipogenesis and glucose production in vitro, and circulating concentrations of insulin, triiodothyronine (T3) and thyroxine (T4) to determine the effects of chronic or acute dietary treatments. 2. Giving the 300 g protein/kg diet or withholding feed for 1 d decreased (P less than 0.05) lipogenesis in vitro compared with controls. 3. Giving the 120 g protein/kg diet or refeeding with a 210 g protein/kg diet for 1 or 2 d increased (P less than 0.05) lipogenesis in vitro compared with controls. Glucose production was affected in the same manner. 4. Fasting decreased (P less than 0.05) plasma insulin and T3 and increased T4. Both refeeding and a low-protein diet increased T3. Refeeding increased and a low-protein diet decreased insulin. 5. Chronic use (7-28 d of age) of either an alternating protein or intermittent feeding regimen caused greater responses compared with acute bouts (single cycle) of either of the regimens.

Animals↗

PubMed1989

A diabetic-like condition of turkey embryos maintained in shell-less culture.

Serum insulin concentration and pancreatic insulin content were determined for turkey embryos incubated in ovo and in long-term shell-less culture (ex ovo). Insulin was undetectable (less than 10 pg) in serum from 87% of the ex ovo embryos compared with their in ovo counterparts. This was evident at all incubation ages, although insulin was detectable in more of the ex ovo embryos on Day 24. Insulin increased in the embryos incubated in ovo from 122 (Day 15) to levels exceeding 2000 pg/ml at hatching. Total pancreatic insulin content was greater in the cultured embryos on Days 15, 17, and 22 compared with their in ovo counterparts. Serum glucose was significantly greater (P less than 0.05) in the ex ovo embryos at all ages. In response to an infusion of L-arginine, serum insulin increased from 566 to 1256 pg/ml in the in ovo embryos, whereas no change was evident in the ex ovo embryos (233 vs 257 pg/ml). When embryos incubated in ovo were injected with insulin, a significant (P less than 0.05) reduction of serum glucose was observed at 60 min after injection. Serum glucose concentrations remained elevated in the embryos incubated ex ovo despite the insulin injection. Liver glucose 6-phosphatase activity, assessed on Days 15 and 22 of incubation, was found to be significantly (P less than 0.05) lower in the ex ovo embryos. Turkey embryos incubated in shell-less culture exhibited chronic hyperglycemia in concert with extremely low circulating levels of insulin. The pancreatic beta cells of these embryos were not responsive to arginine or elevated glucose. Taken together these findings suggest the occurrence of a diabetic-like condition in the ex ovo embryos. This defect in insulin secretion may, in part, be responsible for some of the developmental abnormalities characteristic of the turkey embryo cultured ex ovo.

Animals↗

PubMed1988

Effect of early feed restriction in male broiler chicks on plasma metabolic hormones during feed restriction and accelerated growth.

1. Plasma GH was greater (P less than 0.05) on day 12 in ad libitum-fed birds compared to restricted chicks. Conversely, maximum GH levels were found to occur in the nutrient restricted chicks during the period of accelerated growth (day 42). 2. A significant decline in circulating insulin concentrations with advancing age was evident in both ad libitum-fed and restricted chicks. 3. Feed restriction significantly suppressed circulating T3 in restricted chicks, with concentrations returning to control levels upon refeeding. 4. A significant increase in T4 with advancing age was evident in both treatment groups, with T4 being significantly greater in controls compared to restricted chicks at 54 days of age.

Age Factors↗

PubMed1988

Chicken hepatic metabolism in vitro. Protein and energy relations in the broiler chicken--VI. Effect of dietary protein and energy restrictions on in vitro carbohydrate and lipid metabolism and metabolic hormone profiles.

1. Ross male broiler chicks growing from 14 to 28 days of age were fed 14 and 20% protein diets (4 kcal day-1/body wt0.66) or 20 and 28% protein diets (2.8 kcal day-1/body wt0.66) in a 2 x 2 factorial arrangement to determine the effects of protein and energy intakes on in vitro lipogenesis (IVL) and net glucose production (NGP). Plasma concentrations of insulin, glucagon, thyroid hormones (T3 and T4) and somatomedin-C (Sm-C) were estimated by radioimmunoassay. 2. There was a significant (P less than 0.05) decrease in IVL in the chicks given the higher daily protein intake. 3. The higher protein intake increased (P less than 0.05) NGP while the lower energy intake decreased (P less than 0.05) NGP. 4. Insulin, both thyroid hormones and Sm-C were affected by dietary energy and protein intakes.

Animals↗

PubMed1988

Corticosterone implants and supplemental dietary ascorbic acid effects on lipid metabolism in broiler chicks.

Male broiler chicks were fed diets containing either 0 or 300 ppm ascorbic acid from hatch to 49 days of age. At 35 days of age, chicks were implanted with 50 mg of corticosterone to study a possible interaction between dietary ascorbic acid and corticosterone on body, liver, adrenal, and abdominal fat pad weights. In vitro lipogenesis was determined from the incorporation of 20 mM [2-14C] sodium acetate into hepatic lipids during a 2-h incubation at 37 C. The corticosterone implants increased (P less than .05) liver and abdominal fat pad weights and in vitro lipogenesis but decreased (P less than .05) body and adrenal weights. Dietary ascorbic acid had little affect upon these traits.

Adipose Tissue↗

PubMed1987

Characterization of the chicken muscle insulin receptor.

Insulin receptors are present in chicken skeletal muscle. Crude membrane preparations demonstrated specific 125I-insulin binding. The nonspecific binding was high (36-55% of total binding) and slightly lower affinity receptors were found than are typically observed for crude membrane insulin binding in other chicken tissues. Affinity crosslinking of 125I-insulin to crude membranes revealed insulin receptor alpha-subunits of Mr 128K, intermediate between those of liver (134K) and brain (124K). When solubilized and partially purified on wheat germ agglutinin (WGA) affinity columns, chicken muscle insulin receptors exhibited typical high affinity binding, with approximately 10(-10) M unlabeled insulin producing 50% inhibition of the specific 125I-insulin binding. WGA purified chicken muscle insulin receptors also exhibited insulin-stimulated autophosphorylation of the beta-subunit, which appeared as phosphorylated bands of 92- and 81K. Both bands were immunoprecipitated by anti-receptor antiserum (B10). WGA purified membranes also demonstrated dose-dependent insulin-stimulated phosphorylation of the exogenous substrate poly(Glu,Tyr)4:1. However, unlike chicken liver, chicken muscle insulin receptor number and tyrosine kinase activity were unaltered by 48 hr of fasting or 48 hr of fasting and 24 hr of refeeding. Thus, despite the presence of insulin receptors in chicken muscle showing normal coupling to receptor tyrosine kinase activity, nutritional alterations modulate these parameters in a tissue-specific manner in chickens.

Animals↗

PubMed1987

Insulin metabolism and its effect on blood electrolytes and glucose in the turkey hen.

Insulin half-life (T1/2) was determined to be similar between egg-laying and non-laying turkey hens, averaging 7.5 vs 8.7 min, respectively. Infused insulin lowered plasma glucose 25% in both groups although the time course of each response was different. Circulating phosphorous decreased 30 min following insulin treatment and returned to preinjection concentrations at the end of sampling. Insulin initiated immediate decreases in plasma calcium and magnesium. It is evident that insulin is involved in electrolyte metabolism as well as glucose metabolism in birds.

Animals↗

PubMed1987

Measurement of glucose and lipid metabolism in avian liver explants.

1. A mechanical tissue chopper was used to obtain 35-75 mg explants from 21- to 28-day-old chick liver to determine assay conditions (substrates, buffers, time), regulators (metals and hormones) and points of endogenous regulation of de novo lipogenesis (ATPase, reductive potential and protein phosphorylation). High- and low-bicarbonate-based buffers (Earl's balance salts, EBSS and Hanks' balanced salts, HBSS; respectively) were used in conjunction with sources and types of bovine serum albumin (BSA), divalent cations (Mg2+ or Ca2+), substrate (glucose or acetate) and hormones (insulin and catecholamines). 2. Neither EBSS nor HBSS changed in vitro lipogenesis, CO2 or glucose production when 20 mM HEPES was added to these salts. 3. Neither the presence nor the source of BSA (Sigma or Armour) affected metabolism. In contrast, reducing the vessel reaction surface area (5.1 vs 10.5 cm2) decreased metabolic rates. 4. Acetate was more readily utilized than glucose as an in vitro fatty acid precursor. Use of glucose was complicated by production of glucose from endogenous precursors and by label recycling. Divalent cations (Mg2+ or Ca2+) had little affect upon lipogenesis. 5. Chicken insulin (50 ng/ml) did not affect lipogenesis; however, incorporation of acetate into fatty acids was decreased by dibutyryl cyclic AMP. A catecholamine-induced decrease in vitro lipogenesis indicates that major points of regulation are under control of phosphorylation-dephosphorylation steps.

Acetates↗

PubMed1987

Effects of starvation and refeeding on tissue zinc, copper and iron in turkey poults.

The effects of starvation and refeeding of 2-wk-old turkey poults on serum and tissue levels of zinc, copper and iron were investigated. Serum concentrations of zinc and copper declined during 4 d of starvation. Refeeding for 24 h following a period of starvation restored serum copper to levels similar to those in the fed controls but failed to elevate zinc levels. Liver concentrations and total quantities of zinc, copper and iron increased throughout starvation. Refeeding the starved poults reduced hepatic metal concentrations but caused a further increase in total metal content. This was apparently related to the large increase in liver mass, and the effect was most pronounced in poults starved 1 d prior to refeeding. Starvation also caused an increased zinc concentration and content and a reduced copper content in the pancreas, duodenal mucosa and kidney. Iron content of the pancreas and kidney increased during starvation, but that of the duodenal mucosa declined. Starvation evoked a progressive increase in the cytosolic zinc concentration from liver, pancreas, duodenal mucosa and kidney. A major part of this increase was accounted for as zinc bound to metallothionein (MT). Refeeding rapidly reduced cytosolic and MT-bound zinc in each of these tissues. It was concluded that starvation and refeeding had major effects on tissue trace metal status. A function is proposed for MT during starvation as a mechanism for the conservation of body zinc stores. Zinc, released as a consequence of tissue catabolism, is repartitioned into a soluble storage site (MT), which can be rapidly mobilized to meet the demands of new tissue synthesis once anabolic metabolism resumes.

Animal Nutritional Physiological Phenomena↗