Cachetin/TNF-alpha in septic shock and septic adult respiratory distress syndrome.
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Animals↗
Biomedical subjects
S F Lowry
Publications and source records attributed to S F Lowry.
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↗
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↗
Cachectin/TNF mediates the pathophysiological effects of bacterial endotoxin/lipopolysaccharide (LPS).
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Animals↗
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↗
Effect of the route of nutrient administration on whole-body protein kinetics in man.
The kinetic mechanism resulting in nitrogen (N) retention during oral or continuous intravenous feeding (IVF) was investigated in normal subjects and hospitalized patients. The whole-body protein turnover rate (Q) in these adult subjects was estimated using a primed-constant infusion of 15N-glycine and measuring the isotope enrichments in urinary urea and ammonia. Based on a stochastic model, the total protein synthesis (S) and breakdown (C) rates were calculated from N excretion and intake. These protein kinetic responses were studied either after brief (two or three days) or extended (ten days) fasting or during the fourth day of defined formula oral feeding or the tenth to 14th day of parenteral repletion by IVF. The mean daily intake during feeding was 270 +/- 7 mg N/kg and 28 +/- 2 nonprotein kcal/kg. The results from a total of 120 studies are summarized. In the absence of any N intake, depleted patients with cancer demonstrated a higher Q (+16%), with increased S (+25%) than depleted patients without cancer or acutely depleted normals. In all groups, protein kinetics were increased to a greater extent by oral feeding, compared to IVF. All subjects are in positive N balance during feeding and the mean N retention is 32 +/- 3%, which is not different among groups. Protein accretion during oral feeding is due to an increase in S and a similar decrease in C of body protein. During IVF this is achieved by a larger decrease in C with relatively little or no change in S.
Administration, Oral↗
Cachectin: a pluripotent hormone released during the host response to invasion.
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Animals↗
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↗
Effect of hormonal and substrate backgrounds on cell membrane function in normal males.
Hormonal and substrate influences on in vivo cellular membrane function were evaluated in 15 healthy male volunteers. Each subject underwent serial evaluations of membrane function in the anterior tibialis muscle, as assessed by transcutaneous measurement of resting membrane potential (Em). Group A subjects (n = 9) underwent measurement of resting Em in the basal state and again during the 10th day of intravenous feeding (IVF). Group B subjects (n = 6) underwent measurement of resting Em in the basal state during epinephrine infusion and again during epinephrine infusion on the 7th day of IVF. Percutaneous needle biopsy of the vastus lateralis muscle permitted calculation of transmembrane electrolyte distribution from the Nernst equation, using the measured Em and the chloride space method. Hospitalization with intake of a defined-formula enteral diet for 3 days resulted in depolarization (P less than 0.05) of resting Em (-75.3 +/- 1.6 mV) compared with normal (-79.8 +/- 0.9 mV). Despite 10 days of subsequent IVF, further depolarization (P less than 0.05) of resting Em (-71.2 +/- 1.2 mV) was observed. In the dual presence of IVF and exogenous epinephrine infusion, there was an increase (P less than 0.05) in intracellular potassium concentration and repolarization of resting Em (-80.6 +/- 0.8 mV) to normal levels. These data indicate that hormonal background and substrate availability contribute to the in vivo modulation of cellular membrane function in human skeletal muscle, possibly through facilitation of sodium-dependent amino acid transport across the cell membrane.
Adult↗
Cachectin/tumor necrosis factor induces lethal shock and stress hormone responses in the dog.
Cachectin/tumor necrosis factor has been implicated as a mediator of lethal endotoxemia, but the metabolic and hemodynamic responses to this macrophage-derived peptide have been incompletely characterized. Cachectin was administered by intra-arterial infusion in two groups of beagle dogs at lethal (100 micrograms per kilogram) and sublethal (10 micrograms per kilogram) doses. The infusion produced serum cachectin levels (1 to 50 nanomoles per liter) similar to those achieved after experimental endotoxemia. The lethal response to cachectin was characterized by progressive hypotension, shock and death within three hours. Histopathologic findings included acute inflammation of the pulmonary interstitium, intravascular thrombosis with hemorrhagic necrosis, adrenal medullary necrosis and acute renal tubular necrosis. Cachectin infusion precipitated significant increases of plasma catecholamines, cortisol and glucagon in a dose response manner. Cachectin infused directly into the isolated hindlimb mediated reductions of skeletal muscle resting transmembrane potential and stimulated lactate efflux. Cachectin appears to occupy a crucial role in physiopathologic responses to infection, and likely participates in the mobilization of host energy stores, intravascular depletion and shock after lethal endotoxemia.
Animals↗
Comparison of numerical and phenotypic leukocyte changes during constant hydrocortisone infusion in normal humans with those in thermally injured patients.
Twenty-four to 48 hours after thermal injury, percentages and number of T X mu or T4 lymphocytes decrease with little or no change in T X gamma or T8 cells. Additionally, the plasma hydrocortisone level is extremely elevated. Since administration of hydrocortisone to normal humans also produces a specific decrease in T X mu or T4 lymphocytes, it was hypothesized that burn induced elevations of hydrocortisone were responsible for the decrease in T X mu/T4 cells. In this study, normal humans were administered constant infusions of hydrocortisone for six hours, such that plasma levels were increased to an extent that mimics those 24 to 48 hours after thermal injury. Before, during and after infusion, percentages and numbers of lymphocytes, monocytes, granulocytes and T3, T4, T8, T11, HLA-DR and Leu7 lymphocytes were quantified by flow cytometry. Results were compared with those for patients with burns. The plasma hydrocortisone level rose to 49.0 micrograms per deciliter during infusion, similar to the mean of 47.5 micrograms per deciliter for patients with burns. Infused volunteers showed significant lymphopenia, monocytopenia and granulocytosis. Additionally, there were significant decreases in percentages of T3, T4 and T11 lymphocytes, no significant changes in percentages of T8 or HLA-DR and an increase in percentages of Leu7+ cells. These changes in lymphocyte subsets mimicked those of burn patients. Numbers of T3, T4 and T11 cells significantly decreased during hydrocortisone infusion while numbers of T8, HLA-DR and Leu7 lymphocytes did not change. Burn patients showed decreased numbers of T3 and T4 cells, but this T3/T4 lymphopenia was not as great as during hydrocortisone infusion. These results support the hypothesis that elevation of hydrocortisone is responsible for the lymphocyte phenotypic changes that occur in the early postburn period.
Adult↗
Shock and tissue injury induced by recombinant human cachectin.
Cachectin (tumor necrosis factor), a protein produced in large quantities by endotoxin-activated macrophages, has been implicated as an important mediator of the lethal effect of endotoxin. Recombinant human cachectin was infused into rats in an effort to determine whether cachectin, by itself, can elicit the derangements of host physiology caused by administration of endotoxin. When administered in quantities similar to those produced endogenously in response to endotoxin, cachectin causes hypotension, metabolic acidosis, hemoconcentration, and death within minutes to hours, as a result of respiratory arrest. Hyperglycemia and hyperkalemia were also observed after infusion. At necropsy, diffuse pulmonary inflammation and hemorrhage were apparent on gross and histopathologic examination, along with ischemic and hemorrhagic lesions of the gastrointestinal tract, and acute renal tubular necrosis. Thus, it appears that a single protein mediator (cachectin) is capable of inducing many of the deleterious effects of endotoxin.
Animals↗
Cachectin/tumor necrosis factor mediates changes of skeletal muscle plasma membrane potential.
Lethal infections are associated with cellular dysfunction as evidenced by a decrease in the resting transmembrane potential difference (Em) of skeletal muscle fibers. Endotoxin stimulation of macrophages evokes production of cachectin, a protein that has been implicated as a mediator of the lethal effects of endotoxemia. In the present study, rat skeletal muscle fiber Em decreased when incubated with recombinant human cachectin. The reduction of Em induced by cachectin occurred in a dose-related fashion and was inhibited by mAb against the monokine. Infusion of cachectin induced a decline of skeletal muscle Em in vivo, and suggests that cachectin may acutely mediate alterations of skeletal muscle membrane function after infection.
Animals↗
Peripheral tissue metabolism in man with varied disease states and similar weight loss.
The purpose of this study was to identify the effects of tumor burden and benign inflammatory disease on peripheral tissue metabolism independent of antecedent weight loss. This was accomplished by comparing forearm substrate flux profiles in cachectic cancer and benign disease patients to those of normal subjects before and after 10 days of total protein calorie depletion. Tumor-bearing patients (CA), benign disease patients (BD), and starved (ST) normal volunteers had similar weight loss. Resting energy expenditure was not significantly different between the study populations. Efflux of total amino acids (TAA [nmole/100 ml tissue-min]) decreased significantly (P less than 0.05) in the normals after 10 days of starvation (-886 +/- 185 postabsorptive (PA) vs -278 +/- 60 (ST]. CA patients had TAA efflux of -428 +/- 52 which was significantly (P less than 0.05) less than PA normals. In contrast, BD patients had a significantly (P less than 0.05) elevated TAA efflux of -895 +/- 165 compared to ST normals. CA patients had a significantly (P less than 0.05) elevated glucose uptake and lactate efflux compared to ST normals (glucose: +1.12 +/- 0.21 (CA) vs +0.11 +/- 0.09 (ST), lactate: -0.84 +/- 0.13 (CA) vs -0.38 +/- 0.13 (ST) [mumole/100 ml tissue-min]). The data suggest that tumor-bearing patients are able to maintain their peripheral tissue protein sparing adaptation to nutritional depletion in the presence of accelerated glucose utilization. However, clinically stable patients with benign disease do not demonstrate this adaptation and may be at greater risk for lean tissue dissolution than previously appreciated.
Adult↗
Cancer cachexia and the rate of whole body lipolysis in man.
While malnutrition attending cancer cachexia may be associated with variable losses of body fat, lipid metabolism has been only minimally studied. To clarify potential aberrations of lipid metabolism in weight losing cancer patients, the whole body rate of lipolysis was determined in 9 cancer patients in the postabsorptive state and compared to that in 5 normal subjects. A primed-three stage infusion of glycerol was used to measure plasma glycerol clearance and turnover. A positive correlation between glycerol turnover and plasma concentration was demonstrated in both cancer patients (r = 0.72) and in normal subjects (r = 0.81). Glycerol turnover rate in cancer patients (2.05 +/- 0.14 mumol X kg-1 X min-1) was not different from that in normals (2.31 +/- 0.50); while glycerol clearance in cancer patients (1.72 +/- 0.13 L/min) was significantly lower (P less than 0.025) by 32% than that in normals. This study demonstrates that the whole body lipolytic rate in cancer patients is not different from healthy normals. As a consequence, the loss of body fat in patients with cancer cachexia may be due to a reduced rate of lipogenesis rather than augmented lipolysis as is observed in nonmalignant malnutrition, starvation, or injury.
Adult↗
Influence of increasing dietary intake on whole body protein kinetics in normal man.
The whole body protein kinetic response to increasing dietary intake was studied in 20 normal adult male subjects receiving a defined formula diet orally. Each person received the same amount for 5 days at the rate ranging from 150 to 330 mgN/kg. day and 16 to 34 kcal/kg. day, keeping the calorie to nitrogen ratio as constant. Whole body protein flux was measured using a primed constant infusion of 15N glycine and determining isotopic enrichments in the urinary urea and ammonia. Whole body protein synthesis and breakdown rates were calculated from the flux measurement and nitrogen excretion and intake. The mean protein turnover (Q), synthesis (S) and breakdown (C) rates for all subjects were 3.72+/-0.42, 2.47+/-0.47 and 2.12+/-0.39 g protein/kg. day. These values increased with increasing dietary nitrogen intake up to 270+/-4 mgN/kg. day which is twice the daily recommended protein requirement for a normal adult man and then tended to decrease. Nitrogen intake in the range of 150 to 270 mg N/kg. day showed significant positive correlations with nitrogen balance, Q, S and S/C and the protein accretion was due to a relatively large increase in S compared to that in C. When the intake rate exceeded 270 mg N/kg. day, the nitrogen balance was still positive but now due to a larger decrease in C. These results show that the kinetic parameters of whole body protein metabolism in adult man appear to exhibit a maximum at a dietary nitrogen intake twice the daily requirement level. The mechanism of the maintenance of protein balance changes at this threshold.
Journal Article↗
Total parenteral nutrition in patients with insulin-requiring diabetes mellitus.
The clinical course of 24 patients with insulin-requiring diabetes mellitus who had received total parenteral nutrition (TPN) was retrospectively analyzed. Routine nutritional assessment disclosed significant depression of anthropometric indices and secretory protein levels in patients with chronic renal failure complicating juvenile onset diabetes mellitus (JODM). Biochemical complications including hypo- or hyperglycemia were significantly more frequent (p less than 0.001) in JODM than in maturity-onset diabetes and found to a lesser degree in patients with renal failure. The catheter infection rate was substantially higher (17%) than usually encountered in TPN therapy. Positive nitrogen balance was achieved in the majority of patients with an average 84% and 92% of estimated protein and caloric requirements being provided. Close monitoring and a protocol of infusion plus supplemental subcutaneous regular insulin was useful in providing adequate TPN safely to these high-risk patients.
Acute Kidney Injury↗
Extremity amino acid metabolism during starvation and intravenous refeeding in humans.
This study was designed to evaluate peripheral tissue amino acid metabolism in normal subjects who underwent starvation followed by intravenous administration of a nutritional repletion regimen with varying nonprotein caloric sources. Extremity amino acid (AA), arteriovenous differences, and blood flow were measured across forearm and/or leg of 12 healthy male subjects. Plasma AA flux [(arterial concentration - venous concentration) X flow X (1 - hematocrit); ml X min-1 X 100 ml tissue-1] was determined postabsorptively (PA), after 10 days of starvation (ST) and on the 10th day of intravenous feeding (IVF). There was a significant (P less than 0.05) decrease in efflux of total amino acids during the starvation study (-345 +/- 74) compared with the PA study (-1,463 +/- 263). Peripheral tissue AA uptake increased significantly (P less than 0.05) after 10 days of IVF (+276 +/- 79) compared with both PA and ST studies. There were no significant differences in extremity AA flux between those subjects who received 100% dextrose and those receiving 50% dextrose-50% lipid as a nonprotein caloric source. Linear relationships of AA infusion rate (IR) to AA flux (r = 0.845, P less than 0.001) and AA IR to [AA]art IVF (r = 0.842, p less than 0.001) were observed during IVF. Results of this study suggest that extremity flux determinations during IVF cannot be interpreted without correction for AA availability as reflected by AA infusion rate.
Amino Acids↗