Ethical dilemmas in managed care.
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Ethics, Medical↗
Biomedical subjects
J E Fischer
Publications and source records attributed to J E Fischer.
Sepsis increases skeletal muscle sodium, potassium-adenosinetriphosphatase activity without affecting messenger RNA or protein levels.
BACKGROUND: Previous studies suggest that sodium, potassium-adenosinetriphosphatase (Na+, K(+)-ATPase) activity in skeletal muscle is increased during sepsis, but the molecular mechanisms are not well understood. We tested the hypothesis that increased muscle Na+,K(+)-ATPase activity during sepsis is associated with increased expression of messenger RNA for the Na+,K(+)-ATPase alpha-1, alpha-2, and beta-1 subunits and increased amounts of the enzyme protein. STUDY DESIGN: Extensor digitorum longus muscles were harvested from rats 16 hours after induction of sepsis by cecal ligation and puncture or sham operation. The Na+,K(+)-ATPase activity was determined spectrophotometrically. Messenger RNA levels for the alpha-1, alpha-2, and beta-1 subunits of Na+,K(+)-ATPase were determined by Northern blot analysis. Enzyme protein levels were measured by Western blot analysis and tritium-ouabain binding assay. RESULTS: Muscle Na+,K(+)-ATPase activity was 46 percent higher in rats that had sepsis than in rats that underwent sham operation (p < .05). No significant differences between septic and control groups were noted in messenger RNA levels for the Na+,K(+)-ATPase subunits. Western blot analysis and tritium-ouabain binding revealed no difference in enzyme protein expression between septic and control animals. CONCLUSIONS: Results suggest that sepsis increases skeletal muscle Na+,K(+)-ATPase activity without affecting enzyme messenger RNA or protein levels. The results are consistent with an increased catalytic constant for individual Na+,K(+)-ATPase protein units, an atypical mechanism for this enzyme.
Animals↗
Refractory hypothalamic adenylate cyclase in anorectic tumor-bearing rats: implications for NPY-induced feeding.
Although isoproterenol stimulated adenylate cyclase activity in hypothalamic membranes taken from freely-feeding, food-restricted or nonanorectic tumor-bearing rats, the response was greatly reduced in anorectic tumor-bearing rats. The addition of NPY to the membrane preparation inhibited adenylate cyclase activity in hypothalamus taken from freely-feeding and food-restricted rats, but NPY-inhibitory activity was significantly reduced in both groups of tumor-bearing rats. These results suggest that cyclic AMP formation is refractory in anorectic tumor-bearing rats, and that NPY-induced inhibition of hypothalamic adenylate cyclase is reduced in tumor-bearing rats prior to the onset of significant anorexia. Therefore, NPY-induced feeding may be reduced in tumor-bearing organisms due to a dysfunction in the cyclic AMP second messenger system.
Adenylyl Cyclases↗
Coronary angioplasty compared with bypass grafting.
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Angioplasty, Balloon, Coronary↗
We hold these truths....
It is traditional in an address of this kind in surgical organizations for a great social, national, professional issue to be analyzed, often quite correctly and brilliantly. A clarion call for a plan of action is outlined, actions that are succinctly and brilliantly captured. If you peruse most of the Presidential Addresses of surgical organizations, you will find that as a pattern. I am not certain I can do that very well. I am not sure I know what to tell you about the nation's and the world's problems. I am not sure that if I had an action plan, it would have any credibility or that anybody would follow it, however correct it might be. And so, rather than making pronouncements about the all too real issues that confront us, what I would like to talk about are some matters that underlie all that we do--the constants--those aspects that at least I perceive as truths underlying what we do. Some of you may argue that these matters have little or nothing to do with the scientific organization or scientific meeting and will not convey anything of value. I hope to prove you incorrect. I hope at the end of this brief talk that you will take something away from it. Certainly I am sincere in my offering. I am not trying to sound arrogant or accomplished, nor do I presume to know all the answers. These are merely observations and things I think about.
General Surgery↗
Differential expression of intestinal and splenic cytokines after parenteral nutrition.
OBJECTIVE: To determine the effect of parenteral nutrition (PN) on the expression of message for inflammatory cytokines in the spleen and different segments of the intestine. DESIGN: Randomized controlled trial. PARTICIPANTS: Eleven adult male Sprague-Dawley rats weighing 250 to 300 g. INTERVENTIONS: All rats underwent central venous cannulation and were randomized to two groups. Group 1 (n = 6) received saline solution infusion and chow ad libitum; group 2 (n = 5) received lipid-free PN with no oral feeding. After 7 days, the animals were killed and the spleens and segments of small and large intestine were removed. MAIN OUTCOME MEASURES: The expression of message for tumor necrosis factor alpha (TNF-alpha), interleukin-6 (IL-6), and IL-1 in the spleen and intestine was determined using a semiquantitative reverse transcription polymerase reaction. Splenic macrophages were isolated and cultured for 24 hours with and without lipopolysaccharide. Production of TNF-alpha and IL-6 was determined by bioassay followed by enzyme-linked immunosorbent assay. RESULTS: After 7 days of infusion, messenger RNA (mRNA) expression for TNF-alpha, IL-1, and IL-6 was increased in the jejunum (P < .05), and TNF-alpha mRNA and IL-6 mRNA expression was decreased in the spleen (P < .01) of PN-fed animals when compared with saline/chow controls. In addition, TNF-alpha mRNA expression was increased in the cecum (P < .05), IL-1 mRNA expression was increased in the ileum (P < .05), and IL-6 mRNA expression was increased in the cecum (P < .05) and Peyer's patches (P < .007) in the PN-fed animals. Production of TNF-alpha and IL-6 by splenic macrophages was decreased following PN infusion in both lipopolysaccharide-treated and untreated cultures (P < .05). CONCLUSIONS: Infusion of lipid-free PN induces a differential mRNA expression for inflammatory cytokines in the spleen and intestine with an overall up-regulation of the expression of inflammatory cytokines in the intestine and a down-regulation in the spleen. These data provide evidence that the regulatory mechanisms for cytokine production are different in the intestine and the spleen. Further study is needed to elaborate the mechanism of this differential expression following lipid-free PN infusion.
Animals↗
Nitric oxide inhibits LPS-induced IL-6 production in enterocytes.
In recent studies, production of interleukin-6 (IL-6) in cultured enterocytes was stimulated by lipolysaccharide (LPS). In other cell types, IL-6 production was inhibited by nitric oxide (NO). We tested the hypothesis that LPS-induced IL-6 production in the enterocyte is regulated, at least in part, by NO. IEC-6 cells (a rat intestinal epithelial cell line) were cultured for 3 days with different combinations of LPS (1-10 micrograms/ml), the NO synthase inhibitor N-omega-nitro-L-arginine (NNA, 3-300 microM), L-arginine (10 mM), the NO donor sodium nitroprusside (SNP, 0.5-1 microM), or medium alone as control. IL-6 levels in the culture medium were determined by the B9 murine hybridoma bioassay. Nitrite, a stable end product of NO metabolism, was measured by HPLC. PCR was performed to determine inducible NO synthase (iNOS) mRNA expression in the IEC-6 cells. Treatment of IEC-6 cells with LPS stimulated IL-6 production. LPS-induced IL-6 production was further increased by NNA in a dose-dependent fashion. This effect of NNA was abolished by the addition of L-arginine. SNP caused a dose-dependent decrease in IL-6 production. Nitrite production was increased in a dose-dependent fashion after LPS treatment. PCR revealed an increase in iNOS mRNA expression in IEC-6 cells after administration of 1 microgram/ml LPS. The results suggest that NO inhibits LPS-induced IL-6 production in the enterocyte. NO may be an important regulator of intestinal cytokine response during sepsis and endotoxemia.
Animals↗
Anticatabolic effect of the beta 2-agonist cimaterol in vivo in tumor-bearing animals.
Loss of lean body mass occurs in cancer and may adversely affect outcome. The beta 2-agonist cimaterol increases muscle mass and protein content in tumor-bearing animals, in part by decreasing protein degradation, but the effect of the drug on protein synthesis remains uncertain. To determine the influence of cimaterol on protein synthesis, a methylcholanthrene sarcoma was transplanted sc into the dorsum of male Fischer-344 rats. After 3 weeks of tumor growth, tumor-bearing and control animals received daily sc injections of the beta 2-agonist cimaterol (0.15 mg/kg) for 5 days. Rate of protein synthesis was measured using iv [3H]-phenylalanine (25 microCi/100 g body wt) and cold phenylalanine (150 mumole/100 g body wt) in a flooding dose. Extensor digitorum longus muscles were harvested 10 min later, homogenized, and assayed for [3H]-phenylalanine uptake (bound) (dpm/mg muscle) and tissue-specific (free) radioactivity to determine protein synthesis rate (Ks: %/24 hr). There was a significant increase in protein synthesis rate in control and tumor-bearing animals receiving cimaterol compared to that in freely feeding, food-deprived, or matched-carcass-weight nontumor-bearing controls, as well as compared to that in tumor-bearing controls. We conclude that the anabolic effects of cimaterol are due to both decreased protein degradation and increased muscle protein synthesis. Therefore, beta 2-agonists may prove useful in prevention and/or treatment of cancer cachexia.
Adrenergic beta-Agonists↗
The increased potential for the production of inflammatory cytokines by Kupffer cells and splenic macrophages eight days after thermal injury.
Burn patients often experience a devastating inflammatory response to infection within the first two weeks after thermal injury. The inflammatory cytokines IL-6, TNF and IL-1 have been implicated in this condition but most studies have focused on the abnormal levels of cytokines in the plasma. In this study the production of cytokines was compared for Kupffer cells versus splenic macrophages; endotoxin (LPS) stimulation versus no stimulation; and burn (post burn days 1, 3 and 8) versus no burn (control). Corresponding serum levels of IL-6 were also determined. Kupffer cells from normal or burned animals were shown to produce much higher amounts of the inflammatory cytokines than that produced by splenic macrophages. An exception to this was the equal production of TNF by LPS-stimulated hepatic and splenic cells. Both LPS-stimulated Kupffer cells and splenic macrophages produced larger amounts of the cytokines than that produced by the unstimulated cells. There was a significant effect of thermal injury on cytokine production by LPS-stimulated Kupffer cells at post burn day 8 and on TNF production by stimulated splenic macrophages also at post burn day eight. Although there was a statistically significant effect of thermal injury at post burn day 8 on IL-1 production by unstimulated splenic macrophages, the absolute amount of cytokine produced was very small. The results suggest that by post burn day 8 the cells may have become primed to respond to a stimulus such as endotoxin (LPS), a condition that could arise in a burn patient from sepsis. Strangely, the large spike in serum IL-6 level occurred at post burn day one and the level of the cytokine returned nearly to the control value on post burn days 3 and 8.
Animals↗
Anorectic and neurochemical effects of pituitary adenylate cyclase activating polypeptide in rats.
Pretreatment of rats with intrahypothalamic injections of pituitary adenylate cyclase activating peptide (PACAP) 10 min prior to the injection of neuropeptide Y (NPY) significantly reduced food and water intake during the 4-h measurement period. Intrahypothalamic injection of PACAP in schedule-fed rats also reduced food and water intake for 2 h. A smaller 1-h reduction of water intake was observed in water-deprived rats, suggesting that the anticonsummatory effects of PACAP were primarily against food intake. PACAP treatment did not alter hypothalamic concentration of NPY, nor were neurotransmitters, precursors, or metabolites altered substantially in corpus striatum or nucleus accumbens regions. These results demonstrate primary anorectic effects of intrahypothalamic injection of PACAP. The demonstration of these anorectic effects may suggest a role of cyclic AMP activation and inhibition in the control of satiety and hunger.
Adenylyl Cyclases↗
Sepsis and endotoxemia stimulate intestinal interleukin-6 production.
BACKGROUND: Endotoxemia stimulates tumor necrosis factor (TNF) and interleukin-1 (IL-1) production in mucosa of the small intestine, but the effect on IL-6 production is not known. Intestinal IL-6 may be especially important, considering its role in the acute phase response. We tested the influence of endotoxemia and sepsis in mice on intestinal IL-6 and IL-6 messenger RNA (mRNA) levels. METHODS: Mice were injected with lipopolysaccharide (LPS 10 mg/kg) or saline solution. In some experiments animals were pretreated with indomethacin (5 mg/kg) or N-nitro-L-arginine (NNA, 100 mg/kg) before LPS injection. In other experiments, sepsis was induced by cecal ligation and puncture (CLP); controls were sham operated. Serum and jejunal mucosa were harvested at intervals during 16 hours, and IL-6 levels were determined by enzyme-linked immunosorbent assay. IL-6 mRNA was detected by polymerase chain reaction. RESULTS: Endotoxemia and sepsis increased serum and mucosal IL-6 and IL-6 mRNA, with maximum levels noted at 1 and 4 hours after LPS and at 8 hours after CLP. Pretreatment of endotoxemic mice with indomethacin or NNA blunted the increase in mucosal IL-6. CONCLUSIONS: Results suggest that sepsis and endotoxemia stimulate IL-6 production in small intestinal mucosa and that this response may be transcriptionally regulated. The effect of endotoxemia may be partly mediated by prostaglandins and nitric oxide. The results also suggest that the intestinal mucosa may be a participant in the cytokine response, rather than just a passive bystander.
Animals↗
Protein synthesis in isolated enterocytes from septic or endotoxaemic rats: regulation by glutamine.
1. We studied the effect of sepsis and the regulation by glutamine of protein synthesis in enterocytes isolated from the small intestine of rats. 2. Sepsis was induced by caecal ligation and puncture; control rats were sham operated. Enterocytes were isolated from the jejunum and incubated in a medium containing [3H]phenylalanine. 3. Sixteen hours after caecal ligation and puncture, protein synthesis, measured as incorporation of radioactivity into protein, was increased by 65%, 89% and 137% respectively in enterocytes from the tips and mid-portions of the villi and from the crypts. 4. Addition of glutamine to incubated enterocytes stimulated protein synthesis in a dose-dependent manner, and this effect was most pronounced in crypt cells from septic rats. The effect of glutamine on protein synthesis was duplicated by equimolar concentrations of acetoacetate or 3-hydroxybutyrate, both of which may serve as fuel for enterocytes, and was blocked by the glutaminase inhibitor 6-diazo-5-oxo-L-norleucine. 5. The results suggest that sepsis stimulates protein synthesis in enterocytes and that glutamine regulates protein synthesis in the same cells, probably by energy provision.
Animals↗
Differential effects of tumor and parenteral nutrition on jejunal mucosal polyamines.
Nutritional repletion of tumor-bearing (TB) organisms by means of total parenteral nutrition (TPN) has been associated with gut atrophy, immunosuppression, and increased infection rate. To assess possible molecular mechanisms of intestinal atrophy during TPN, jejunal mucosal polyamine concentrations and biosynthetic activity were assessed in non-TB (NTB) and TB rats maintained on rat chow or TPN for eight days. As expected, jejunal mucosal protein content was decreased in both groups of rats maintained on TPN. Although mucosal concentration of putrescine was decreased in TB groups and in the NTB group maintained on TPN, levels of spermidine and spermine were decreased only in the NTB-TPN group. Spermidine levels were elevated significantly in both TB groups. The concentration of spermine was also elevated in the TB-TPN group but was not changed in the TB group maintained on chow. Activity of ornithine decarboxylase was increased in the NTB-TPN group but was not altered significantly in either TB group. S-adenosylmethionine decarboxylase activity was decreased significantly in TB rats maintained on chow and was increased back to control level in the TB-TPN group. These results suggest that jejunal mucosal polyamines are decreased in NTB rats maintained on TPN. Additionally, it appears that enzyme activity is induced in NTB-TPN rats, perhaps in response to the reduction in polyamines and gut atrophy. The absence of similar changes in TB rats maintained on TPN suggests that regulatory mechanisms of polyamine biosynthesis, such as product inhibition, may be refractory. In addition, polyamine biosynthesis from other sources, such as tumor tissue, may be affecting the control of intestinal polyamine biosynthesis.
Adenosylmethionine Decarboxylase↗
The metabolic response to laparoscopic cholecystectomy.
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Cholecystectomy, Laparoscopic↗
Neuropeptide Y and the development of cancer anorexia.
OBJECTIVE: The authors determined whether radioligand binding of neuropeptide Y (NPY) to hypothalamus taken from nonanorectic and anorectic tumor-bearing rats was altered as compared with similar tissue taken from freely-feeding and food-restricted control rats. SUMMARY BACKGROUND DATA: Previous results indicate that tumor-bearing rats exhibit a refractory feeding response to NPY, the most potent feeding stimulus known. Additional studies indicate that the concentration of NPY in the hypothalamus of anorectic tumor-bearing rats is decreased as compared with freely-feeding or food-restricted control rats. METHODS: Because these observations of decreased response to exogenous peptide in the presence of decreased endogenous levels suggest an alteration in hypothalamic NPY receptors, this study investigated binding of 125I-NPY to hypothalamic membranes of tumor-bearing and control rats. RESULTS: Determinations of receptor affinity for NPY (half maximal concentration for displacement) indicated a 20-fold decrease in affinity with the development of anorexia, which changed to an 80-fold decrease during severe anorexia. Receptor density, as indicated by specific binding, exhibited only a 30% decrease, even during severe anorexia. CONCLUSIONS: These results suggest major alterations in NPY receptor mechanisms in experimental cancer anorexia, with receptor affinity being decreased progressively as the rats become more anorectic. The absence of a compensatory up-regulation in receptor density in the presence of decreased endogenous NPY concentrations indicate dysfunction in receptor regulatory mechanisms. This receptor aberration may be the central nervous system basis for the etiology of cancer anorexia.
Animals↗
Prolonged studies of perfluorocarbon associated gas exchange and of the resumption of conventional mechanical ventilation.
OBJECTIVE: To determine whether oxygenation and lung mechanics are preserved during perfluorocarbon associated gas exchange of 24 hrs duration and after evaporation of perfluorocarbon. DESIGN: Prospective, experimental animal trials. SETTING: Animal laboratory in a university setting. SUBJECTS: Ten normal, neonatal piglets weighing 2.5 to 4.5 kg. INTERVENTIONS: Ten piglets were anesthetized with fentanyl (25 micrograms/kg/hr), paralyzed with metocurine iodide (0.3 mg/kg) and placed on volume regulated continuous positive pressure breathing instituted at an FIO2 setting of 1.0, tidal volume of 15 mL/kg, respiratory rate of 25 breaths/min and positive end-expiratory pressure of 4 cm H2O. Perfluorocarbon associated gas exchange was initiated by intratracheal instillation of perflouorooctylbromide (30 mL/kg) followed by gas ventilation at the same settings. Evaporative losses were replaced by intratracheal instillation of 2.5 mL/kg/hr of perfluorocarbon. In one group of five piglets, evaporative losses were replaced for 24 hrs until the end of the study. In the other group of five piglets, replacement of perfluorocarbon was discontinued after 2 hrs, although gas ventilation was continued for 24 hrs. Blood gases and lung mechanics were measured in both groups. Histologic evaluation of lungs from both groups of animals was performed. MEASUREMENTS AND MAIN RESULTS: Airway pressures and blood gases were stable throughout the 24-hr study period in both groups. Airway pressures in the evaporative group increased as evaporation of perfluorocarbon neared completion. There was no hemodynamic deterioration during the 24-hr study period. Histology showed good preservation of lung architecture in both groups. CONCLUSIONS: Perfluorocarbon associated gas exchange was safe and effective in normal piglets for a period of 24 hrs. Evaporation of perfluorocarbon and resumption of continuous positive pressure breathing was well tolerated.
Animals↗
The mRNA expression and in vitro production of cytokines and other proteins by hepatocytes and Kupffer cells following thermal injury.
Inflammatory cytokines and acute-phase proteins are closely interrelated, and their levels of production by various cells are increased by thermal injury. It was hypothesized that burn-mediated increases in the production of TNF and IL-6 by Kupffer cells and the production of acute phase proteins by hepatocytes are paralleled by increases in the corresponding message RNA levels in these cells. The mRNA expression of the cytokines, IL-6 and TNF alpha, and acute phase proteins, alpha-1 acid glycoprotein (alpha-1 AGP), and albumin in liver tissue were determined in rats 24 h after thermal injury. Also IL-6 and TNF alpha from in vitro cultured Kupffer cells, and alpha-1 AGP and albumin from in vitro cultured hepatocytes, and the serum levels of these proteins, were determined. An increased expression of IL-6 mRNA in liver tissue from animals of the burned group was accompanied by an elevation of IL-6 released from cultured Kupffer cells and by increased serum levels of this cytokine. Thermal injury caused a decrease in TNF mRNA but no change in the production of this cytokine by Kupffer cells, and TNF could not be found in the serum. Also, an increase in alpha-1 AGP mRNA expression following thermal injury was consistent with the increase of alpha-1 AGP production by hepatocytes and with the elevated serum level of this acute phase protein. Thermal injury caused no change in albumin mRNA expression or in the in vitro production of this negative acute phase protein, however, the serum level of albumin increased. The results suggest that thermal injury may cause alterations in the cytokine and acute phase protein mRNA levels in liver, which may cause alterations in the cellular production and serum levels of the corresponding proteins.(ABSTRACT TRUNCATED AT 250 WORDS)
Acute-Phase Proteins↗
Ethical dilemmas in managed care.
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Cost Allocation↗