Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0036690 (sepsis)
 59,461 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We investigated the ability of pentoxifylline (PTX) to modulate protein synthesis and degradation in the presence and absence of insulin during incubation of epitrochlearis muscle, 2 or 6 days after injection of Escherichia coli. On days 2 and 6 after infection, protein synthesis was inhibited by 25%, whereas proteolysis was enhanced by 75%. Insulin (2 nM) in vitro stimulated protein synthesis in muscles from infected rats to the same extent as in controls. The ability of insulin to limit protein degradation was severely blunted 48 h after infection. On day 6 after infection, insulin inhibited proteolysis to a greater extent than on day 2. PTX suppressed the increase in plasma concentrations of tumor necrosis factor more than 600-fold after injection of bacteria, and partially prevented the inhibition of protein synthesis and stimulation of protein degradation during sepsis. Moreover, PTX administration maintained the responsiveness of protein degradation to insulin during sepsis. Thus cytokines may influence skeletal muscle protein metabolism during sepsis, both indirectly through inhibition of the effects of insulin on proteolysis, and directly on the protein synthesis and degradation machinery.
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PMID:Pentoxifylline improves insulin action limiting skeletal muscle catabolism after infection. 1049 2

Insulin deficiency (e.g., in acute diabetes or fasting) is associated with enhanced protein breakdown in skeletal muscle leading to muscle wasting. Because recent studies have suggested that this increased proteolysis is due to activation of the ubiquitin-proteasome (Ub-proteasome) pathway, we investigated whether diabetes is associated with an increased rate of Ub conjugation to muscle protein. Muscle extracts from streptozotocin-induced insulin-deficient rats contained greater amounts of Ub-conjugated proteins than extracts from control animals and also 40-50% greater rates of conjugation of (125)I-Ub to endogenous muscle proteins. This enhanced Ub-conjugation occurred mainly through the N-end rule pathway that involves E2(14k) and E3alpha. A specific substrate of this pathway, alpha-lactalbumin, was ubiquitinated faster in the diabetic extracts, and a dominant negative form of E2(14k) inhibited this increase in ubiquitination rates. Both E2(14k) and E3alpha were shown to be rate-limiting for Ub conjugation because adding small amounts of either to extracts stimulated Ub conjugation. Furthermore, mRNA for E2(14k) and E3alpha (but not E1) were elevated 2-fold in muscles from diabetic rats, although no significant increase in E2(14k) and E3alpha content could be detected by immunoblot or activity assays. The simplest interpretation of these results is that small increases in both E2(14k) and E3alpha in muscles of insulin-deficient animals together accelerate Ub conjugation and protein degradation by the N-end rule pathway, the same pathway activated in cancer cachexia, sepsis, and hyperthyroidism.
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PMID:Ubiquitin conjugation by the N-end rule pathway and mRNAs for its components increase in muscles of diabetic rats. 1056 3

Endotoxin (LPS), a membrane component of gram-negative bacteria produces multiple endocrine and metabolic effects that mimic those seen in acute sepsis. It induces species-dependent alterations of the growth hormone (GH) axis that may participate in the shift of the metabolism towards catabolic events. Humans and sheep show increased GH secretion in response to LPS, as opposed to rats, which have been the most studied. The purpose of our work was to evaluate the effects in intact rams of an acute intravenous administration of a high dose of LPS on the insulin-like growth factor (IGF)-I/IGF-binding proteins (IGFBPs) system and to analyse the temporal relationship of GH axis changes with those of several hormonal and metabolic parameters such as somatostatin, cortisol, insulin, and glucose. LPS induced a late moderate decrease of total IGF-I plasma levels following a 5-h steady-state period (-26.6+/-4. 2%, P<0.05, 9 h after LPS), despite a biphasic and sustained increase of GH secretion in the same animals (2.48+/-0.39 ng/ml 2 h after LPS and 2.7+/-0.37 ng/ml 5 h after LPS vs 0.77+/-0.10 before LPS; Briard et al. 1998a). Western ligand blot analysis in IGFBPs showed an early short-lasting increase in IGFBP-1 (188.8+/-39% P<0. 05, 3 h after LPS). No significant change was seen for either IGFBP-2, -3 or -4. We observed a marked and sustained increase in cortisol (128.18+/-7.21 ng/ml 3 h after LPS, vs 21.17+/-4.22 before LPS). Insulin also increased (27.69+/-3.90 microU/ml 3 h after LPS, vs 13.48+/-1.69 before LPS) and its burst coincided with that of IGFBP-1. Moderately decreased IGF-I and increased IGFBP-1 plasma levels contrasted with the sustained increase in GH secretion that we recently described, thereby suggesting that endotoxin causes a state of resistance to GH. This may be exacerbated by reduced IGF-I bioavailability and/or action, and which may participate in the pathophysiology of the catabolic state seen in sepsis. The temporal analysis of hormone responses suggests that endotoxin-induced alterations of the IGF-I/IGFBPs system may involve the prolonged and substantial somatostatin rise that we recently demonstrated, together with an increase in glucocorticoid and cytokine as more generally assumed.
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PMID:IGF-I/IGFBPs system response to endotoxin challenge in sheep. 1069 76

In the critically ill, glucocorticoids induce myopathy, combining profound protein catabolism and mild myotubular death. Insulin-like growth factors (IGFs) inhibit muscle catabolism through activation of phosphatidylinositol 3-kinase (PI3K). Using rat L6 myoblasts, we show that IGF-I also acts through PI3K to inhibit apoptosis induced by hyperosmolar metabolic stress with 300 mM mannitol. We find that the glucocorticoid dexamethasone inhibits this antiapoptotic effect of IGF-I by impairing PI3K signaling. Dexamethasone induces overexpression of the PI3K subunit p85alpha, which, in turn, competes with the complete PI3K heterodimer for binding at insulin receptor substrate-1, inhibiting PI3K activation. Dexamethasone blocks IGF-I-induced phosphorylation of Akt, a PI3K-dependent process. Increased cellular p85alpha abundance, induced by either 10 microM dexamethasone or transient transfection with a plasmid coding for p85alpha, significantly inhibits IGF-I rescue from apoptosis induced by mannitol, as indicated by both loss of cell viability and increased activity of caspase-3 by fluorogenic assay. Conversely, constitutively active PI3K inhibits death induced by mannitol, even in the presence of dexamethasone. These findings may have particular relevance in the pathogenesis of acute steroid myopathy in critical illness, in which catabolic glucocorticoid effects combine with acute metabolic stressors, including sepsis, fasting, and chemical denervation.
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PMID:Dexamethasone inhibits insulin-like growth factor signaling and potentiates myoblast apoptosis. 1091 83

Insulin-like growth factor (IGF) binding protein-1 (IGFBP-1) is a 28-kDa plasma protein that binds to IGF-I and IGF-II with high affinity. IGFBP-1 is elevated in the blood as a result of sepsis, AIDS, excessive alcohol consumption, and diabetes and may, in part, be responsible for the wasting observed during these pathophysiological conditions. The liver is the principal site of IGFBP-1 synthesis, and we have previously shown that proinflammatory cytokines can directly stimulate IGFBP-1 secretion in a human hepatoma cell line (HepG2). The purpose of the present study was to investigate the role of the MAP kinase pathway in regulating IGFBP-1 synthesis by IL-1beta. We show that IL-1beta stimulates the phosphorylation of ERK-1 and -2 in a time- and dose-dependent manner. In addition, the MAP kinase-kinase MEK-1 and the ribosomal S6-kinase RSK-1 are also phosphorylated in response to IL-1beta. The transcription factor CREB, a potential substrate of both protein kinase A (PKA) and RSK-1, is phosphorylated in response to IL-1beta and cAMP in HepG2 cells. The ability of IL-1beta to stimulate the expression of IGFBP-1 and the phosphorylation of the above kinases was specifically inhibited by PD98059, a MEK-1 inhibitor. cAMP also stimulated IGFBP-1 synthesis, but PD98059 failed to block the cAMP effect. Conversely, a PKA inhibitor (H-89) inhibited the ability of cAMP, but not IL-1beta to stimulate IGFBP-1 synthesis. The effect of IL-1beta and cAMP on IGFBP-1 messenger RNA (mRNA) accumulation was additive. IL-1beta, cAMP, PD98059, and H-89 had similar effects on the accumulation of IGFBP-1 protein and mRNA. IL-1beta and cAMP did not change the half-life of IGFBP-1 mRNA, but PD98059 and SB202190, a p38 MAP kinase inhibitor, destabilized IGFBP-1 mRNA and blocked the phosphorylation of RSK-1 in response to IL-1beta. Our data demonstrate that the MAP kinase signal transduction pathway plays an important role in the regulation of IGFBP-1 synthesis by IL-1beta.
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PMID:Stimulation of insulin-like growth factor binding protein-1 synthesis by interleukin-1beta: requirement of the mitogen-activated protein kinase pathway. 1096 86

The vascular actions of insulin may contribute to the increase in glucose uptake by skeletal muscle. We have recently shown that when capillary recruitment by insulin is blocked in vivo, an acute state of insulin resistance is induced. Another agent that may have vascular effects is the inflammatory cytokine tumor necrosis factor-alpha (TNF-alpha), which has been reported to play an important role in the insulin resistance of obesity, type 2 diabetes, and sepsis in both animals and humans. Thus, in the present study, we have investigated the effect of an intravenous 3-h TNF treatment (0.5 microg x h(1) x kg(-1)) in control and euglycemic-hyperinsulinemic-clamped (10 mU x min(-1) x kg(-1) for 2 h) anesthetized rats. Hind-leg glucose uptake, muscle uptake of 2-deoxyglucose (2-DG), femoral blood flow (FBF), vascular resistance (VR), and capillary recruitment as measured by metabolism of infused 1-methylxanthine (1-MX) were assessed. Insulin alone caused a significant (P < 0.05) increase in FBF (1.7-fold) and capillary recruitment (2.5-fold), with a significant decrease in VR. In addition, hind-leg glucose uptake was increased (fourfold), as was 2-DG uptake in the soleus and plantaris muscles. TNF completely prevented the insulin-mediated changes in FBF, VR, and capillary recruitment and significantly reduced (P < 0.05) the insulin-mediated increase in total hind-leg glucose uptake (by 61%) and muscle 2-DG uptake (by at least 50%). TNF alone had no significant effect on any of these variables. It is concluded that acute administration in vivo of TNF completely blocks the hemodynamic actions of insulin on rat skeletal muscle vasculature and blocks approximately half of the glucose uptake by muscle. It remains to be determined whether these two effects are interdependent.
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PMID:Acute impairment of insulin-mediated capillary recruitment and glucose uptake in rat skeletal muscle in vivo by TNF-alpha. 1107 58

Changes in cell hydration are critically important for the signalling towards metabolic responses to hormones, substrates and reactive oxygen intermediates. In liver insulin-induced cell swelling is due to a net K(+)-uptake resulting from the concerted activation of Na(+)/K(+)/2Cl(-) cotransport, Na(+)/H(+) exchange and the Na(+)/K(+)-ATPase. Insulin-induced swelling is essential for generating the antiproteolytic response to the hormone, which depends on activation of the MAP-kinase p38. Recent investigations show, that cell swelling induced by either hypoosmolarity or insulin triggers the activation of signalling cascades. Cell swelling by insulin is Ptdins-3-kinase mediated and contributes to the activation of Erk- and p38-type MAP-kinases. Conditions dehydrating insulin target tissues such as hyperosmolarity or amino acid deprivation are frequently associated with insulin resistance. In liver, hyperosmolarity impairs the Ptdins-3-kinase-dependent K(+) uptake and cell swelling in response to insulin, leading to resistance of MAP-kinases and proteolysis to regulation by insulin. Likewise, a reduction of insulin-induced swelling by the loop diuretics furosemide and bumetanide cause insulin resistance shown by the levels of cell swelling, MAP-kinase activation and proteolysis control. Blockage of the cell volume response to insulin may be the common denominator in dehydration-induced insulin resistance found in clinical settings such as sepsis, burn injury and diabetes mellitus.
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PMID:Cell hydration and insulin signalling. 1112 22

The risk of mortality or significant moridity is high among long-stay intensive care unit (ICU) patients. Sepsis, polyneuropathy and multiple organ failure are prominent causes of mortality and morbidity in the ICU. Many ICU patients are hyperglycaemic, presumably reflecting an adaptive development of insulin resistance. We hypothesized that this hyperglycaemia predisposes patients to many of the typical ICU complications, prolonged intensive care dependence and excess mortality. Insulin therapy directed at establishing normoglycaemia was investigated in a series of 1548 ICU patients. An intensive treatment group received insulin infusion tailored to control blood glucose levels in the range 4.4-6.1 mmol/l (80-110 mg/dl), whereas the conventional treatment group only received insulin when glucose levels exceeded 11.1 mmol/l (200 mg/dl) and in that event were maintained in a target range of 10.0-11.1 mmol/l (180-200 mg/dl). Intensive management of blood glucose levels was reflected in a 43% reduction in intensive care mortality risk (P=0.036 after correction for interim analyses) and a 34% reduction in hospital mortality (P=0.01). A reduced risk of infection was reflected in a 46% reduction in the risk of septicaemia (P=0.003) and a 35% reduction in the need for prolonged (>10 d) antibiotic therapy (P<0.001). Regression analysis suggests that control of glucose levels, rather than insulin administration itself, was responsible for the clinical benefits observed. Use of insulin infusion to control glucose levels in ICU patients, at least in populations similar to those in our study, can be expected to achieve clinically welcome improvements in outcome. An algorithm is proposed for implementing this. Further data are needed to establish the applicability of this strategy to other patient groups in the ICU and in general hospital care.
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PMID:Beyond diabetes: saving lives with insulin in the ICU. 1217 17

Diabetic ketoacidosis (DKA) and pancreatic pseudocysts are rare complications following treatment of hematological malignancies with L-asparaginase (L-asp). Persistent hyperglycemia with recurrent DKA presenting as a long-term complication of L-asp-induced pancreatitis is even rarer. A 21-year-old man with pre-B-type acute lymphoblastic leukemia (ALL) developed pancreatic pseudocysts, DKA and persistent hyperglycemia after L-asp therapy. The patient was treated with oral hypoglycemic agents (OHA) for sugar control thereafter. Ten months later, another episode of DKA developed during relapsed ALL without having obvious precipitating factors. Insulin was then instituted for control of his blood sugar until death. The leukemic process may play some role in glucose homeostasis and may be considered as a precipitating factor for DKA. The patient finally died of disease progression of ALL and sepsis 2 years after the initial diagnosis of ALL.
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PMID:Diabetic ketoacidosis and persistent hyperglycemia as long-term complications of L-asparaginase-induced pancreatitis. 1243 31

Skeletal muscle atrophy occurs in multiple clinical settings, including cancer, AIDS and sepsis, and is caused in part by an increase in the rate of ATP-dependent ubiquitin-mediated proteolysis. The expression of two recently identified genes encoding ubiquitin-protein ligases, MAFbx/Atrogin-1 and MuRF1, has been shown to increase during muscle atrophy. Mouse knockout studies have demonstrated that MAFbx and MuRF1 are required for muscle atrophy, and thus might be targets for clinical intervention. A second strategy for blocking atrophy involves the stimulation of pathways leading to skeletal muscle hypertrophy. Insulin-like growth factor 1 (IGF-1) is a protein growth factor that can induce skeletal muscle hypertrophy by activating the phosphatidylinositol 3-kinase (PI3K)-Akt pathway. The pathways modulating hypertrophy and atrophy will be further discussed, to highlight potential targets for clinical intervention.
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PMID:Molecular mechanisms modulating muscle mass. 1292 36


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