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K C Klasing

Publications and source records attributed to K C Klasing.

At least 55 records · Page 3Linked to original sources
PubMed1990

Rates of metallothionein synthesis, degradation and accretion in a chicken macrophage cell line.

To understand the regulation of metallothionein (MT) accretion in a chicken-macrophage cell line, fractional rates of MT synthesis (FRS) and degradation (FRD) were measured by following decay kinetics of [35S]cysteine in MT. To obtain valid measurements, we added various amounts of cysteine to medium to ensure that the isotope tracer was adequately diluted after MT was labeled in the presence of various levels of zinc. We also demonstrated that the measured fractional rate of MT accretion closely approximated the difference between FRS and FRD. All fractional rates were similar for the two MT isoforms isolated. FRD did not change during the 27-hr decay period, but FRS and fractional rate of MT accretion changed over time. FRS of MT was 0.097 and 0.012 hr-1 from 0 to 9 and 9 to 27 hr, respectively, after cells were incubated in medium supplemented with 50 microM zinc. FRD of MT was 0.020 hr-1. Addition of 1100 microM unlabeled cysteine to medium supplemented with 50 microM zinc increased FRD and decreased FRS and fractional rate of MT accretion, as compared with not adding cysteine. Overall, these results indicate that rates of MT synthesis and degradation can both regulate MT accretion. Further experiments with various amounts of zinc and cysteine added to medium suggested that the effect of added cysteine on MT fractional rates was due to chelation of unbound zinc. Elimination of the cysteine effect on MT fractional rates was accomplished by adding more zinc to cysteine-supplemented medium. Thus, the concentration of unbound zinc affects the rates of MT synthesis and degradation.

Animals↗
PubMed1988

On the application of compartmental models to radioactive tracer kinetic studies of in vivo protein turnover in animals.

A mathematical framework is presented for unifying and extending the various compartmental models and formulae used to calculate fractional protein synthesis and degradation rates in animals from data obtained by infusing labelled amino acids. It is shown how the various schemes can be derived as special cases of the product-precursor model or some three-pool variant. Three-compartment representations, which circumvent the need to measure the specific radioactivity of the precursor pool, are proposed. The mathematical solutions are generally presented in a form that is amenable to parameter estimation by non-linear least squares. The problems of measuring the true precursor pool for protein synthesis are addressed, and theoretical consideration is given to assaying aminoacyl-tRNA.

Animals↗
PubMed1988

Nutritional aspects of leukocytic cytokines.

Immune responses result in a variety of metabolic adjustments that are mediated by cytokines of leukocytic origin. Of the dozens of cytokines released during an immune response, interleukin-1 (IL-1), tumor necrosis factor alpha (TNF alpha) and interleukin-6 (IL-6) are the major mediators of intermediary metabolism. These three cytokines act in concert to decrease food intake, increase resting energy expenditure, gluconeogenesis, glucose oxidation, and hepatic synthesis of fatty acids and acute phase proteins, decrease fatty acid uptake by adipocytes and alter the distribution of zinc, iron and copper. Most of these activities result from direct interactions between the cytokine and the responding cells. IL-1, TNF alpha and IL-6 also affect changes in metabolism by changing levels of circulating insulin, glucagon and corticosterone. The nutritional impact of these metabolic changes is dependent upon age. In growing animals, increases in energy expenditure and oxidation of amino acids are balanced by lower needs associated with growth. In adult animals, energy and amino acid requirements are increased by an amount similar to the increased basal metabolic rate and amino acid oxidation. Nutrition also influences the release of cytokines and consequently affects regulation of the immune response. For example, protein deficiency results in decreased IL-1 release and impaired tissue responses to IL-1.

Animals↗
PubMed1988

Decreased amino acid requirements of growing chicks due to immunologic stress.

Experiments were conducted to determine the influence of immunologic stress on methionine and lysine requirements of growing chicks. Immunologic stress was elicited by injection of either Escherichia coli lipopolysaccharide or heat-killed Staphylococcus aureus every other day for 6 d. In the first experiment, diets were formulated to provide methionine levels of 0.30, 0.50 and 0.70%. In the second experiment, diets contained 0.75, 0.90 or 1.2% lysine. In chicks fed amino acid-sufficient diets, those chicks injected with immunogens had slower growth, lower feed intake and poorer efficiency of feed utilization than those injected with saline. The decreases due to immunogens were diminished in chicks fed amino acid-deficient diets. The methionine requirements of saline- and immunogen-injected chicks were above 0.5% and between 0.3 and 0.5%, respectively; the lysine requirements were greater than 0.95% and between 0.7 and 0.95%, respectively. Thus immunogen injection decreased methionine and lysine requirements, probably because of a decreased need of amino acids for growth and tissue accretion. Immunogen-induced depression in serum zinc and increase in serum copper levels were ameliorated by lysine or methionine deficiencies. Compared with saline-injected chicks, immunogen-injected chicks had significantly higher serum interleukin-1 (IL-1) activity by 53% when fed the methionine-sufficient diet, but they did not have significantly greater IL-1 levels when fed the methionine-deficient diet. These observations indicate that the diminished expression of immunologic stress in amino acid-deficient chicks is due to an impaired immune response.

Amino Acids↗
PubMed1988

Influence of acute feed deprivation or excess feed intake on immunocompetence of broiler chicks.

Immunocompetence was determined in chicks subjected to 24 h feed deprivation or excess intake by measuring 1) hemagglutinin titers in response to sheep red blood cell (SRBC) injections given either before or after dietary treatments, 2) delayed hypersensitivity to human gamma globulin (HGG), or 3) in vitro, phytohaemagglutinin-induced mitogenesis of spleen lymphocytes taken immediately or 24 h after dietary treatment. In Experiment 1, chicks were intubated six times during a 24-h period with an isolated soy protein-dextrose diet at either 100% (control) or 150% of ad libitum consumption. Following the period of excess intake, half of the chicks were prevented from making a compensatory decrease in intake by force-feeding (Hi-equal) and half were permitted to decrease their intake (Hi-adlib). All chicks not force-fed were sham-intubated. Imposing force-feeding (Hi-equal) before or after challenge with SRBC resulted in significantly (P less than .05) decreased hemagglutinin titers. Force-feeding (Hi-equal) 24 h prior to HGG injection significantly decreased delayed hypersensitivity. Hi-adlib chicks did not respond differently than controls. In Experiment 2, chicks were either fed ad libitum (control), fasted for 24 or 48 h and then fed ad libitum (Low24-adlib and Low48-adlib), or deprived of feed for 24 or 48 h and then restricted to normal intake (Low24-equal and Low48-equal). Imposing Low24-equal feeding prior to SRBC injection resulted in significantly greater (P less than .05) hemagglutinin titers after 7 days than observed in control chicks. No other differences were seen. These studies demonstrate that an acute period of uncompensated overconsumption or feed deprivation decreases and increases, respectively, selected aspects of the immune response.

Animal Nutritional Physiological Phenomena↗
PubMed1987

Influence of cell sources, stimulating agents, and incubation conditions on release of interleukin-1 from chicken macrophages.

Experiments were conducted to determine the cell source, stimulating agents, and incubation conditions that maximize interleukin-1 (IL-1) release by chicken macrophages/monocytes. Thymocyte co-mitogen proliferation was used to assay IL-1 activity of conditioned or partially purified supernatants. Monolayers of a transformed chicken macrophage cell line, HD11, released greater amounts of IL-1 than adherent cells isolated from peripheral blood, peritoneal cavity, or spleen. E. coli endotoxin and heat-killed S. aureus induced greater release of IL-1 by HD11 and splenic macrophages than latex or a super induction protocol with mezerien. Blocking macrophage eicosanoid synthesis with indomethacin did not influence IL-1 release from HD11 macrophages. Removing low molecular weight compounds from conditioned supernatants by dialysis did not influence IL-1 activity. IL-1 release was increased by incubating macrophages at 42 C compared to 39 C. Thymocyte co-mitogenic activity of IL-1 was increased by incubating thymocytes at 42 C compared to 39 C. Species cross reactivity between chicken and mammalian IL-1 was also investigated. Chicken IL-1 had slight co-stimulation activity on murine thymocytes, but murine and human IL-1 were without activity on chicken thymocytes.

Animals↗
PubMed1987

Immunologically mediated growth depression in chicks: influence of feed intake, corticosterone and interleukin-1.

The effects of an immune response on growth and feed efficiency in chicks and the role of interleukin-1 (IL-1) and corticosterone (Cort) as mediators of the response were investigated. Daily injections of either sheep red blood cells or the inflammatory agent Sephadex resulted in significantly (P less than 0.05) lower rates of weight gain, feed intake and efficiency of feed utilization than controls fed ad libitum, indicating an immunologically mediated stress. Feeding control chicks the same amount of diet as that consumed by immunologically challenged chicks did not completely equalize rates of weight gain. Injections of a crude preparation of IL-1, but not Cort, resulted in weight gain, feed intake and efficiency of feed utilization that were similar to those of immunologically challenged chicks. The concentrations of IL-1 and Cort, measured by bioassay and radioimmunoassay, respectively, in serum from immunologically challenged chicks were significantly higher than in nonchallenged chicks. To determine the influence of IL-1 and Cort on protein accretion in skeletal muscles, the extensor digiti communus and ulnaris lateralis were incubated in the presence of these two hormones at concentrations similar to that seen in serum after an immunologic challenge. Cort did not affect the rate of protein degradation but resulted in rates of protein synthesis that were significantly lower than controls. IL-1 did not affect the rate of protein synthesis but resulted in rates of protein degradation that were about 24% greater than controls.

Animals↗
PubMed1987

Presence of acute phase changes in zinc, iron, and copper metabolism in turkey embryos.

Acute phase changes in trace mineral metabolism were examined in turkey embryos. An endotoxin injection resulted in increased concentrations of serum copper and liver zinc and decreased concentrations of serum zinc in embryos incubated either in ovo or ex ovo. Changes in zinc and copper metabolism occurred when endotoxin either was injected intramuscularly, into the amnionic fluid, or administered onto the chorioallantoic membrane. Unlike poults, embryos did not respond to an inflammatory challenge with decreased serum iron concentrations. Acute phase changes in embryo serum zinc and copper as well as liver zinc concentrations were similar to those in poults. Increased liver zinc concentrations were associated with increased zinc in metallothionein (MT). An injection of a crude interleukin 1 preparation into embryos resulted in similar increases in hepatic zinc and MT concentrations as an endotoxin injection, suggesting a role for this cytokine in mediating the acute phase changes in embryonic zinc metabolism.

Acute-Phase Reaction↗
PubMed1987

Growth characteristics, protein synthesis, and protein degradation in muscles from fast and slow-growing chickens.

Developmental changes in muscle growth were studied in Single Comb White Leghorn (SCWL) and broiler-type (B) chickens. The extensor digiti communus (EDC) and ulnaris lateralis (UL) muscles were chosen for study because these muscles can be maintained in vitro, permitting the direct measurement of the fractional rate of protein synthesis (FSR) and the fractional rate of degradation (FDR). These muscles were removed from chicks at 1, 5, 10, and 20 days of age. Muscles for B were heavier, grew at a faster rate, and had greater fractional rates of growth than muscles from SCWL. Muscle protein concentrations were similar for SCWL and B. The deoxyribonucleic acid (DNA) concentrations were greater in EDC muscles from SCWL than B at all time periods. Concentrations of DNA were greater in UL muscles from SCWL than B after Day 1. The FSR and FDR were measured in muscles incubated in vitro. At 9 days of age, FSR in broiler and SCWL chicks was not significantly different in either muscle. The FDR was 12 and 19% lower in broiler EDC and UL muscles, respectively, demonstrating that broiler EDC and UL muscles accrete protein at a greater rate and more efficiently than SCWL muscles because of a slower rate of protein degradation. The FSR and FDR were also compared in B and SCWL chicks of 8 and 11 days, respectively, with equal DNA unit sizes. The FSR in B was 27 and 13% greater in EDC and UL muscles, respectively, demonstrating that protein synthesis per nucleus is greater in B chicks.

Animals↗
PubMed1985

Regulation of protein degradation in chick muscle by several hormones and metabolites.

Experiments were conducted to examine the effect of various regulatory agents on the rate of protein degradation in chick extensor digiti communis (EDC), and ulnaris lateralis (UL) muscles in vitro. Muscles were incubated in an oxygenated Krebs-Ringer bicarbonate buffer. Rates of protein degradation were calculated from the rate at which tyrosine was released from protein. Protein synthesis was blocked with cycloheximide to prevent reutilization of tyrosine. Insulin (bovine) decreased protein degradation in the EDC and UL muscles by 11.3 and 10.5%, respectively, when glucose was present in the incubation medium and by 11.0 and 10.3% when glucose was omitted. This suggested the action of insulin on protein degradation was not secondary to effects on glucose transport. Glucose alone decreased protein degradation by 17.3 and 14.8% in EDC and UL, respectively. Glucagon (bovine), cortisol, corticosterone, and dexamethasone did not have significant effects on the rate of protein degradation in either muscle. Branched chain amino acids (BCAA) decreased the rate of protein degradation by 21.6% in the presence of insulin but did not significantly change the rate when insulin was omitted. These results demonstrate that chicken muscle, like that of rats, responds to insulin, glucose, and BCAA by decreasing protein degradative rates. The rates of protein degradation in three muscles, EDC, UL, and extensor digitorum longus (EDL), were compared utilizing a medium containing insulin, glucose, and BCAA to minimize protein degradation. All three muscles released tyrosine at a linear rate for 2.25 hr of incubation. The rate of protein degradation in the slowest growing EDC muscle was significantly greater than that in the UL, whereas the fastest growing EDL had the slowest rate of protein degradation.

Adrenal Cortex Hormones↗
PubMed1984

Effect of inflammatory agents and interleukin 1 on iron and zinc metabolism.

Injection of either sheep red blood cells (SRBC), Escherichia coli, endotoxin, starch, or Sephadex into chicks significantly decreased plasma iron and zinc concentrations. After injection of E. coli or SRBC, plasma zinc was decreased maximally by 52% at 12 h and 15.7% at 48 h, respectively. A second exposure to SRBC or E. coli did not further decrease plasma iron or zinc. Injection of a crude preparation of interleukin 1 isolated from endotoxin-stimulated peritoneal monocytes induced hypozincemia, hypoferremia, increased the concentration of liver metallothionein, and increased liver-zinc concentrations. It is proposed that interleukin 1 mediates the changes in trace mineral metabolism that occur during inflammation and that loss of zinc from plasma is due in part to a sequestration of zinc by liver.

Animals↗
PubMed1984

The effects of intestinal Escherichia coli 263, intravenous infusion of Escherichia coli 263 culture filtrate and iron dextran supplementation on iron metabolism in the young pig.

An experiment using 32 pigs in a 2(3) factorial arrangement of treatments was used to determine the effects on the (1) level of iron dextran supplementation, (2) iv infusion of an Escherichia coli 263 culture filtrate and (3) presence of E. coli 263 in a ligated intestinal segment, on the ability of the young pig to limit systemic Fe availability. Iron dextran was administered im 3 d postpartum. Culture filtrate was infused iv, E. coli were injected into ligated intestines and blood sampling was started at 14 d postpartum. Blood was taken every 2 h for 22 h, after which pigs were euthanized and livers, spleens and kidneys were removed. Pigs receiving 400 mg of iron dextran (HiFe) exhibited greater serum Fe (SFe) and lower total Fe-binding capacity (TIBC) than pigs injected with 100 mg Fe (LoFe). The effects of the E. coli culture filtrate infusion appeared to be associated with endotoxin-induced circulatory shock. The presence of E. coli in the intestine increased TIBC in LoFe pigs, but not in HiFe pigs. The increase in TIBC coincided with the time of maximal fluid secretion into the intestine. Intestinal E. coli also caused an increase in liver Fe content, particularly in HiFe pigs. These data suggest that intestinal E. coli can cause a shift of Fe from the plasma to the reticuloendothelial system, and pigs receiving high supplemental dosages of Fe are less able to limit the availability of Fe to microorganisms.

Animals↗
PubMed1984

Changes in plasma, tissue, and urinary nitrogen metabolites due to an inflammatory challenge.

Studies were undertaken to define the changes in protein metabolism that result from stimulation of the immune system by noninfectious inflammatory agents. Chicks were injected with inflammatory agents and metabolite concentrations were determined between 4 and 48 hr postchallenge. Inflammatory agents resulted in a generalized decrease in the concentration of plasma nitrogen metabolites, including ammonia, uric acid, urea, and several amino acids. Escherichia coli and sheep red blood cell (SRBC) injections induced changes in the concentrations of tissue-free amino acids at 16 hr postchallenge. After E. coli injections, free amino acid concentrations were increased by 175% in muscle and decreased by approximately 25% in liver, spleen, and bursa. A SRBC challenge resulted in similar decreases in free amino acid concentrations in the spleen and bursa as did E. coli; however, muscle and liver free amino acid concentrations were mostly unchanged. Urinary ammonia was increased, urinary uric acid was decreased, and urinary amino acids were not affected by E. coli injection. These findings indicate that stimulation of the immune system by noninfectious inflammatory agents induces tissue-specific changes in nitrogen metabolism. Changes in amino acid pool sizes in various tissues suggest alterations in rates of protein synthesis or degradation.

Amino Acids↗
PubMed1984

Changes in protein synthesis due to an inflammatory challenge.

Rates of protein synthesis in various chick tissues were examined 16 hr after an inflammatory challenge. Protein synthetic rates were calculated from the rate at which [14C]leucine was incorporated into protein and the specific activity of [14C]leucine in the precursor pool. An injection of either Escherichia coli or sheep red blood cells (SRBC) decreased the rate of protein synthesis in the gastrocnemius muscle, and increased the rate in liver, bursa, spleen, and thymus. E. coli, but not SRBC, decreased protein synthesis in the pectoralis muscle. E. coli significantly decreased the aggregation of pectoralis muscle polysomes and increased the aggregation of polysomes in the thymus, bursa, and spleen. E. coli increased the aggregation of free, but not bound, polysomes in liver, suggesting an increase in synthesis of export proteins. SRBC significantly increased polysomal aggregation in bursa and spleen only. A crude preparation of leukocyte endogenous mediator, isolated from peritoneal macrophages, decreased muscle-polysomal aggregation. These studies indicate that tissue-specific changes in protein synthesis occur after a noninfectious inflammatory challenge. These changes may be part of a homeostatic mechanism which supports the immune response.

Animals↗
PubMed1984

Changes in protein degradation in chickens due to an inflammatory challenge.

Tissue-specific changes in protein catabolism were examined in chicks 16 hr following an inflammatory challenge. It was determined that tyrosine was not catabolized or converted to phenylalanine in muscle, thymus, bursa, or spleen. Therefore, rates of tyrosine release from protein were used to estimate rates of protein catabolism in these tissues. Arginine was not catabolized to urea by chick liver; consequently, arginine release from liver protein was used to measure protein catabolism in this tissue. An injection of sheep red blood cells (SRBC) or Escherichia coli did not change rates of protein catabolism in liver or bursa as compared to saline-injected controls. SRBC significantly increased protein catabolism in muscle and spleen by 29 and 15%, respectively. E. coli resulted in significant increases in muscle, spleen, and thymus of 43, 30, and 34%, respectively. These changes in protein catabolism, together with known changes in protein synthesis, suggest that an inflammatory response to SRBC and E. coli result in increased protein accretion in the bursa and liver, and net protein loss from muscle.

Animals↗
PubMed1982

Involvement of food intake and amino acid catabolism in the branched-chain amino acid antagonism in chicks.

The role of food intake and branched-chain amino acid (BCAA) catabolism in the branched-chain amino acid antagonism was investigated. A diet containing crystalline amino acids as the sole source of amino acids was formulated to contain adequate levels of all required nutrients. The basal diet contained 0.60% isoleucine, 0.82% valine and 1.2% leucine. Increasing dietary leucine to 5.0% resulted in reduced food consumption, weight gain, and efficiency of food utilization. These effects were prevented by increasing dietary isoleucine and valine to 0.80 and 1.07%, respectively. When L-[1-14C]isoleucine or L[1-14C]valine were included in the diet, the amont of 14CO2 exhaled was increased within 24 hours of feeding the 5% leucine diet. The excretion of 14C was unaffected by leucine. It was determined by force feeding that approximately 70% of the reduced growth rate in chicks fed the leucine-supplemented diet ad libitum could be accounted for by reduced food intake. A portion of the growth depression may be due to increased BCAA catabolism, limiting the availability of valine and isoleucine for growth.

Amino Acids↗
PubMed1980

Effects of iron on the anti-coli capacity of sow's milk in vitro and in ligated intestinal segments.

The effect of iron on the ability of sow's milk to suppress Escherichia coli was examined both in vitro and in ligated intestinal segments of neonatal pigs. Sow's milk from day 7 of lactation was diluted with NaHCO3/KH2PO4 and divided into four treatment groups: (1) diluted milk; (2) diluted milk + ferric citrate; (3) diluted milk heated at 100 degrees for 20 minutes, and (4) treatment 3 + ferric citrate. Treatment groups were tested for antibacterial activity in vitro after inoculation of 10(4) Escherichia coli (strain 263); counts after a 3-hour incubation were: 721, 9,290, 11,400 and 9,680 for treatments 1-4, respectively. The same four treatments were tested in ligated intestinal segments of 9-day-old pigs with or without the addition of 10(4) E. coli. The average total E. coli count (+10(5)) per centimeter of intestine for 16 pigs after 3 hours of incubation were: 11, 50, 84 and 249 for treatments 1-4, respectively, without additional E. coli and 14, 110, 314 and 535 with additional E. coli. The effects of exogenous iron on the in vitro anti-coli capacity of sow's milk were also examined at 3-day intervals throughout the first 21 days of lactation. Iron had a significant detrimental effect on the anti-coli capacity of sow's milk from days 6 to 18 of lactation. Iron did not have an effect on the anti-coli capacity of colostrum, which exhibited bactericidal activity, or on milk from the 21st day of lactation, which allowed good E. coli growth. Results from these studies suggest that iron reduces the capacity of sow's milk to repress E. coli concentrations both in vitro and in vivo.

Animals↗