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Biomedical subjects

K J Tracey

Publications and source records attributed to K J Tracey.

At least 109 records · Page 6Linked to original sources
PubMed1989

Cachectin/TNF or IL-1 alpha induces cachexia with redistribution of body proteins.

Macrophage secretory products are suspected to participate in the severe lean tissue wasting related to chronic illness. The protein metabolic effects of chronic, 7-day cachectin/tumor necrosis factor (cachectin) or interleukin 1 alpha (IL-1 alpha) administration in vivo were studied in male Wistar rats that were 1) freely fed, 2) pair fed, 3) total protein and calorie starved, 4) twice daily lipopolysaccharide (LPS) administered, 5) twice daily cachectin administered, and 6) twice daily IL-1 alpha administered. LPS, cachectin, or IL-1 alpha administration produced anorexia; weight loss in these groups was comparable to respective pair-fed animals. However, LPS, cachectin, or IL-1 alpha accelerated peripheral protein wasting while preserving liver protein content, unlike the pattern in the pair-fed or starved animals in which loss of liver proteins and relative preservation of skeletal muscle protein were observed. The decrease in skeletal muscle protein content in LPS- or cytokine-treated animals was associated with coordinate decreases in muscle mRNA levels for the myofibrillar proteins myosin heavy chain, myosin light chain, actin, and in the 18S and 28S subunits of ribosomal RNA. We conclude that chronic exposure to the cytokines, IL-1 alpha or cachectin, can simulate those body and muscle protein changes seen in experimental LPS administration or chronic disease and markedly differ from the pattern of protein redistribution due to caloric restriction.

Animals↗
PubMed1989

Intravenous refeeding blocks growth hormone (GH)-provoked rises in serum free fatty acids and blunting of somatotroph response to GH-releasing hormone in normal men.

We measured the serum GH responses to GHRH (1 micrograms/kg) in six normal men who had been rendered hyperinsulinemic and hypolipidemic by 10 days of total parenteral nutrition (TPN subjects) with a 25% dextrose-amino acid solution. The men underwent GHRH testing after 3 h of infusion of NaCl or Met-human (h) GH (2 micrograms/kg.h). The results of these tests were compared with those of five men tested in the post-absorptive state (PA subjects). The serum GH response to GHRH during NaCl infusion was significantly lower in the TPN subjects than in the PA subjects. During the Met-hGH infusion, the serum GH response to GHRH in the PA subjects was significantly lower than that after the NaCl infusion, whereas in the TPN subjects the response was similar to that during the NaCl infusion. The mean integrated areas under the GH response-time curve after GHRH treatment were 3963 +/- 2086 min/micrograms.L following NaCl infusion and 413 +/- 64 min/micrograms.L following Met-hGH infusion in PA subjects; they were 1127 +/- 500 min/micrograms.L following NaCl infusion and 1456 +/- 682 min/micrograms.L during Met-hGH infusion in the TPN subjects. The Met-hGH infusions resulted in a significant increase in serum FFA concentrations in the PA, but not the TPN, subjects. These results suggest that hyperalimentation induces a metabolic background which inhibits GH secretion, as manifested by a diminished serum GH response to GHRH administered after NaCl infusion. The absent FFA response to Met-hGH infusion in the TPN subjects may explain why the Met-hGH infusion in them did not result in a reduced serum GH response to GHRH as occurred in the PA subjects. Hence, FFA may play an important role in the effects of short term Met-hGH infusion on GH secretion.

Adult↗
PubMed1988

Cachectin/tumor necrosis factor induces cachexia, anemia, and inflammation.

Cachexia is a potentially lethal syndrome of unknown etiology characterized by anorexia, weight loss, and protein wasting that frequently complicates the treatment of chronic inflammation and cancer. Cachectin/TNF was isolated during the search for a humoral mediator of cachexia and found to stimulate the breakdown of energy stores from adipocytes and myocytes in vitro, but the chronic effects of the monokine in vivo are not known. Sublethal doses of recombinant human cachectin administered twice daily for 7-10 d caused cachexia in rats, as evidenced by reduced food intake, weight loss, and depletion of whole-body lipid and protein stores. Significant anemia is also observed and found to be the result of decreased red blood cell mass, not expanded plasma volume. Leukocytosis and histopathological evidence of tissue injury and inflammation are observed in several organs, including omentum, liver, spleen, and heart. These data suggests that the exposure of the normal host to cachectin is capable of inducing a pathophysiological syndrome of cachexia, anemia, and inflammation similar to that observed during inflammatory states or malignancy.

Anemia↗
PubMed1988

Tumor necrosis factor-enhanced leukotriene B4 generation and chemotaxis in human neutrophils.

In an in vivo study of five normal volunteers infused with endotoxin (20 U/kg of US reference endotoxin lot EC-5), increased neutrophil (PMN) generation of leukotriene B4 and chemotaxis to leukotriene B4 were found concomitantly with elevated plasma tumor necrosis factor (TNF) levels. To clarify the role of TNF in PMN activation, neutrophil responsiveness after in vitro treatment with TNF was examined. Neutrophils from seven normal subjects were incubated with TNF for 30 minutes and tested for chemotaxis to leukotriene B4, formyl-methionyl-leucyl-phenylalanine and zymosan-activated serum, or the calcium ionophore A23187 to assess leukotriene B4 generation. A range of 10(-13) to 10(-9) mol/L of TNF was used for these assays. When 10(-9) mol/L of TNF was used, the amount of leukotriene B4 that was produced was significantly greater than in control cells. The effect of TNF on PMN chemotaxis was uniformly inhibitory for the three stimuli at 10(-10) mol/L compared with untreated cells. At a picomolar range, PMN migration to leukotriene B4, but not to zymosan-activated serum or formyl-methionyl-leucyl-phenylalanine, was significantly increased over that of PMNs not exposed to TNF. This suggests that TNF has a specific facilitatory effect on PMN responsiveness for both leukotriene B4 production and chemotaxis to leukotriene B4 and may be the same signal for this phenomenon in endotoxemic patients.

Calcimycin↗
PubMed1988

Influence of substrate background on peripheral tissue responses to growth hormone.

To evaluate the effects of substrate and hormonal background on the peripheral response to methionyl human growth hormone (met-hGH), metabolic measurements were performed in 10 normal subjects before and at the end of a 6-hr infusion of met-hGH. Five subjects were studied in the postabsorptive state and five were studied on the 10th day of intravenous repletion. Measurements of hormonal levels, serum amino acid levels, and free fatty acid levels, as well as extremity amino acid and free fatty acid fluxes, were performed. Met-hGH in the postabsorptive setting had no effect on extremity amino acid flux but significantly increased extremity free fatty acid efflux. In contrast, met-hGH in the background of intravenous feeding produced a significant extremity uptake of total amino acids but had no effect on free fatty acid flux. These data suggest a relationship between the substrate background and the actions of met-hGH on both peripheral protein and lipid metabolism. Therefore, the adequacy and composition of the feeding regimen may be important when considering growth hormone as an adjunct to nutritional therapy.

Adult↗
PubMed1988

Protein and substrate metabolism during starvation and parenteral refeeding.

1. Healthy male volunteers underwent 10 days of hospitalized protein-calorie starvation and a subsequent 10 day repletion phase with complete intravenous nutritional support (IVF). Non-protein calories were provided as either all D-glucose or as 50% D-glucose/50% lipid. 2. In comparison with starvation, whole-body protein breakdown, as assessed by [15N]glycine, [13C]leucine and urinary excretion of 3-methylhistidine (3-MH), was diminished during IVF. The administration of parenteral nutrition did not specifically suppress peripheral tissue protein breakdown, as measured by extremity 3-MH efflux. 3. Despite the differential insulin response to D-glucose/amino acid (50 +/- 6 m-units/ml) as compared with the D-glucose/lipid/amino acid regimen (25 +/- 4 m-units/ml), there was no difference in nitrogen retention between the regimens. Indirect calorimetric determinations revealed that oxidation of substrate during IVF was related to the proportion of D-glucose and lipid infusion.

Adult↗
PubMed1988

Cachectin: a hormone that triggers acute shock and chronic cachexia.

Septic shock and invasive infection are diseases caused by humoral mediators of both exogenous and endogenous origin. The search for and identification of these factors has led to the discovery and molecular cloning of cachectin. This pyrogenic cytokine is identical to tumor necrosis factor (TNF) and, when released into the circulation, causes profound shock and multiple organ injury. Cachectin antibodies protect against the lethal effects of mice given endotoxin and baboons given E. coli, a result suggesting that this mediator is both necessary and sufficient to provoke septic shock. Cachectin is produced in humans after endotoxin infusion; the infusion of small doses of TNF is associated with fever, rigors, headache, and hypotension. Septicemic patients also produce cachectin, and during meningococcal infection, patients with the highest serum levels of cachectin die. Chronic cachectin production causes a potentially lethal syndrome of cachexia, anemia, and protein and lipid wasting. Future investigation is being directed toward the development of cachectin antibodies for use in treating the humorally mediated systemic complications of infectious disease.

Animals↗
PubMed1988

Submaximal exercise during intravenous hyperalimentation of depleted subjects.

The peripheral nitrogen wasting and loss of functional capacity caused by the malnutrition of disease and the immobilization of hospitalization may not be readily reversed by refeeding alone. In order to examine submaximal exercise as an adjunctive anabolic stimulus to intravenous refeeding (IVF) in depleted subjects, 14 volunteers were studied in the postabsorptive (PA) state, after 10 days of total starvation, and again after 10 days of nutritional repletion with I.V. feedings. The subjects were randomized to one group that received IVF alone and one group that performed 1 hour of submaximal (51% of VO2max) stationary bicycle exercise daily during IVF. The exercised group was not significantly different from the nonexercised group in urinary nitrogen balance, resting energy expenditure, extremity amino acid flux, or maximal oxygen consumption. Acute exercise did not induce significant derangements in electrolytes or counter-regulatory hormone concentrations. Ten days of submaximal exercise does not appear to be detrimental in this population recovering from moderate hospitalized malnutrition, but additional anabolic stimulae may be needed for improvements in protein accrual or functional capacity.

Adult↗
PubMed1988

Differential neutrophil activation before and after endotoxin infusion in enterally versus parenterally fed volunteers.

This study was done to determine whether or not increased susceptibility to infection seen in enterally versus parenterally fed patients was caused by altered neutrophil (PMN) responsiveness. To determine the differential effects of route of feeding on human PMN activation, plasma C3a levels, circulating PMN counts, PMN migration to leukotriene B4 (LTB4), the peptide, N-formyl-methionyl-leucyl-phenylalanine (FMLP) and zymosan activated serum (ZAS) and generation of LTB4 were assayed before and after and infusion of endotoxin. Nine normal volunteers were enterally (n=4) or parenterally (n=5) fed a diet sufficient to maintain body weight for seven days prior to a standard challenge of endotoxin. Samples were taken prior to the infusion and hourly thereafter for six hours. Prior to the injection of endotoxin, significant differences were seen in the two feeding groups. Plasma C3a levels, absolute circulating PMN counts and chemotaxis to LTB4 were all significantly (p less than 0.02) elevated in the enterally fed group. Generation of LTB4 was higher in the intravenously fed group at base line than the orally fed group (p less than 0.05). Plasma C3a levels rose in the enterally fed group, but not in the intravenously fed group, at two hours after infusion. Neutrophil counts rose in both feeding groups after endotoxin infusion; but the change in percentage was greater in the enterally fed group than in the intravenously fed group. Chemotaxis to FMLP and ZAS was not different during the study and did not differ between the two feeding can have significant impact on neutrophil function and that parenteral nutrition may impair host responsiveness.

Chemotaxis↗
PubMed1988

Cytokine appearance in human endotoxemia and primate bacteremia.

The results of recent work have demonstrated that endotoxin elicits the production of several immunopeptide cytokines that likely mediate the development of septic shock. Bolus injection of endotoxin (20 units per kilogram of body weight) to four volunteers resulted in peak serum cachetin/tumor necrosis factor (TNF) levels of 358 +/- 166 picograms per milliliter within 90 minutes after challenge (p less than 0.05 versus base line) and peak serum interleukin-1 levels of 2.14 +/- 0.89 units per milliliter within two hours after challenge. By contrast, the infusion of a lethal dose of live Escherichia coli to four baboons revealed peak serum cachectin/TNF levels of 20,500 +/- 9,890 picograms per milliliter within 90 minutes after bacteria were given (p less than 0.05 versus base line) and peak interleukin-1 levels of 14.2 +/- 10.1 units per milliliter three hours after bacterial challenge. No detectable monokine levels were observed in either model six hours after challenge. Interferon-gamma levels reached a peak of 2.67 +/- 1.66 nanograms per milliliter in baboon sera at eight hours after bacterial infusion and was no longer detectable by 12 hours. Interferon-gamma was not detected in the sera of humans. These results suggest that the transient release of cachectin/TNF, followed by interleukin-1 and interferon-gamma, may participate in the cascade of events noted in overwhelming bacterial invasion.

Adult↗
PubMed1988

The effect of starvation and total parenteral nutrition on skeletal muscle amino acid content and membrane potential difference in normal man.

Skeletal muscle intracellular amino acids and transmembrane potential difference (Em) were measured in hospitalized volunteers during starvation and refeeding with total parenteral nutrition (TPN). Healthy volunteers underwent extremity amino acid flux measurement, percutaneous skeletal muscle biopsy and determination of skeletal muscle Em after ten days of starvation (ST), and after a subsequent ten day period of TPN. ST produced a significant (p less than 0.05) decrease in plasma essential amino acids when compared with normal ambulatory volunteers. Subsequent administration of TPN produced a significant extremity uptake of all essential amino acids except for threonine and uptake of the nonessential amino acids taurine, glutamate, tyrosine and arginine. ST produced a significant reduction in skeletal muscle free intracellular glutamine and a significant increase in isoleucine and leucine. These changes in free intracellular amino acids were not reversed by administration of TPN. At the conclusion of ten days of ST and ten days of TPN, there was a significant reduction (p less than 0.05) in skeletal muscle Em. The results demonstrate that abnormalities of intracellular amino acid concentrations and reduction of muscle Em are not specific to stress conditions, but rather they can be present during both unstressed ST and intravenous nutritional repletion.

Adult↗
PubMed1987

Physiological responses to cachectin.

Mammals infected with parasitic, bacterial or viral organisms or bearing tumours characteristically display a catabolic state and weight loss which can advance to cachexia (or wasting), shock and death. Although the phenomenon is commonly observed in many parasitic diseases its mechanism is not understood. We have identified and isolated a macrophage protein, cachectin, as the molecule that may be responsible for cachexia and shock. Cachectin is produced by macrophages in response to endotoxin or a number of other bacterial or protozoal products. The released cachectin acts as a hormone, binding to specific high affinity receptors and eliciting biological responses. In the adipocyte anabolic enzymes such as lipoprotein lipase are suppressed through the selective inhibition of mRNA production. An intriguing aspect of cachectin is its pivotal role in the pathogenesis of endotoxin-induced shock. Cachectin causes fever and anorexia and can induce lethal shock and tissue injury in experimental animals. During its chemical characterization cachectin was shown to be identical to tumour necrosis factor (TNF), a macrophage protein that kills tumour cells. This finding emphasizes the extensive range of effects associated with this protein. Cachectin has many properties in common with interleukin 1 but binds to a different receptor and lacks structural homology. Presumably, low levels of cachectin help the host in its battle to remove invasive pathogens, but extensive production of cachectin can lead to shock and catabolic stress hormone responses. These findings have added a new dimension to the biological properties of cachectin, its production, and its role in cachexia and shock.

Animals↗
PubMed1987

Thermogenic and nitrogen response to submaximal exercise in parenterally repleted normal man.

To determine whole-body energy and nitrogen responses to submaximal exercise during repletion levels of intravenous feeding (IVF), five normal male volunteers were hospitalized and underwent serial changes in nutritional intake consisting of weight-maintaining oral feeding (4 d), starvation (10 d), and weight-increasing parenteral feeding (10 d). Twelve-hour aliquots for urinary nitrogen, creatinine, and 3-methylhistidine were collected during the final 36 h of oral feeding and IVF. During these experimental periods, indirect calorimetry was utilized to determine resting oxygen consumption and that occurring during a 1-h period of submaximal (40% of maximal) upright, bicycle exercise. Despite differences in the route of nutrient delivery, oxygen uptake during a fixed rate of exercise (75 W) was similar during oral (16.7 +/- 0.4 mL X kg-1 X min-1) and IVF (14.7 +/- 1.0 mL X kg-1 X min-1). When compared with basal urinary losses, submaximal exercise resulted in diminished nitrogen (p less than 0.01, oral) and 3-methylhistidine (p less than 0.05, oral; p less than 0.01, IVF) excretion during a 12-h post-exercise recovery period.

Adult↗