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Query: UMLS:C0020672 (hypothermia)
 17,327 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Moderate hypothermia may reduce subsequent neuronal damage after traumatic brain injury. Interleukin (IL)-6 may have a role in the pathogenesis of traumatic neuronal damage or repair. Using the enzyme-linked immunological sorbent assay (ELISA), we serially measured IL-6 levels in plasma obtained from the radial artery (systemic) and internal jugular vein (regional) in 13 cerebral trauma patients who underwent hypothermia of 32-33 degrees C ranged from 4-9 days postinjury and 10 head-injured patients who were maintained at normothermic levels (36-37 degrees C). In both patient populations, surface cooling was used since even in the normothermic group, cooling was needed to maintain patient temperature in the normothermic range. All patients were mechanically ventilated after injection of midazolam and vecuronium. The administration of these agents were continued until the end of the study. Hypothermia was typically maintained for four days, however, in some cases based upon CT findings and/or intra-cranial pressure change, the duration was prolonged. No significant differences were found between the two groups in age, gender and Glasgow Coma Scale upon admission. Further, no differences were found in terms of the classification of computed tomography findings or the occurrence of pupillary abnormalities on admission. The patients in this study had not sustained either abdominal or thoracic trauma. Before inducing hypothermia, IL-6 levels in the arterial and internal jugular venous blood exceeded the normal range. Specifically, the internal jugular plasma levels were significantly higher than those in the arterial plasma. While IL-6 levels in the normothermic group did not decrease even at 4 days postinjury, the plasma cytokine levels fell at both sites sharply after moderate hypothermia. The cytokine suppression found in the hypothermic group continued even after rewarming in these patients showing an improved clinical course, but not in those whose condition worsened. In addition to these changes in cytokine levels, the Glasgow Outcome Scale at 6 months postinjury was significantly higher in the hypothermic group than in the normothermia group. Based on the above, this clinical study with its small patient sample size suggests the need for further prospective randomized studies to examine the role of cytokine suppression in the beneficial effects of moderate hypothermia in patients with traumatic brain injury.
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PMID:Effect of moderate hypothermia on systemic and internal jugular plasma IL-6 levels after traumatic brain injury in humans. 1019 70

IFNgamma potentiates the production of serum cytokines and mortality induced by LPS, but these responses do not change in parallel, and the underlying mechanisms are not clear. Pretreatment of mice with 15 microg rrIFNgamma intraperitoneally (IP) resulted in potentiation of LPS-induced serum cytokine production and hypothermia, but these changes depended on the pretreatment time and did not occur in parallel. TNFalpha and IL1beta levels showed peak potentiation after 8-h-IFNgamma pretreatment which may result from a process of sensitization of mechanisms involved in LPS responses. IL6 levels were most markedly potentiated after 3- and 6-h-IFNgamma-pretreatment and hypothermia was markedly potentiated after 0-8 h pretreatments. These effects may result from an additional synergistic action of IFNgamma with other mediators when it is present at significant levels earlier after its injection, given that IFNgamma had little (hypothermia) or no effect (cytokines) alone. The degree of potentiation induced by 18-h-IFNgamma pretreatment was related to the dose of LPS, the maximum response having been increased. Two injections of IFNgamma at 42 and 18 h prior to LPS induced greater increases in TNFalpha and IL1beta production than 18-h pretreatment alone, but not in IL6 production or hypothermia. There may be a maximum level of IL6 production which was surpassed under these conditions. These findings suggest that a balance of sensitizing and synergistic actions of IFNgamma with other mediators such as IL1 and TNFalpha, are the major mechanisms underlying its potentiation of LPS responses in mice.
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PMID:Dual mechanisms of action of interferon-gamma in potentiating responses to LPS in mice: IL1, TNFalpha and IL6 production in serum and hypothermia. 1032 86

The systemic inflammatory response to cardiopulmonary bypass (CPB) is associated with increased production of cytokines. This systemic inflammatory response characterized by the activation of interleukin-6 (IL-6) and interleukin-8 (IL-8) during and after CPB is well documented. A prospective, randomized, double-blind study was performed so as to understand the effects of low-dose methyl prednisolone sodium succinate (MPSS) on the circulating levels of serum cytokines and clinical outcome. Twenty patients were randomly divided into two groups on the basis of the administration of low-dose (1 mg/kg) MPSS (n = 10) and placebo (n = 10) into the pump prime solution. All patients were scheduled to undergo a primary elective coronary artery bypass grafting operation. Patients receiving concurrent corticosteroids, salicylates, dipyridamol or anticoagulants were excluded from the study. Other exclusion criteria were concurrent chronic obstructive pulmonary disease, chronic renal failure, insulin-dependent diabetes, congestive cardiac failure, peptic ulcer history, prior cardiac operations, recent (in a one-month period) myocardial infarction and steroid dependency. Mild systemic hypothermia (30-32 degrees C, rectal) was assured during the CPB. Four blood samples were drawn from the radial artery catheter immediately before starting CPB (T1), following protamine administration (T2) and at 24 (T3) and 48 h (T4) after completion of CPB. In each sample, creatine kinase-myocardial band (CK-MB), white blood cell (WBC), IL-6 and IL-8 levels were measured. IL-6 and IL-8 concentrations were measured by enzyme immunoassay and enzyme-linked immunoabsorbant assay methods. Serum IL-6 T2 and serum IL-6 T3 levels were significantly higher than IL-6 T1 levels in both groups (p < 0.001) and (p < 0.01), and there was no significant elevation in serum IL-8 levels in either group. Serum IL-6 levels were significantly higher in the placebo group than in the MPSS group at T3 (p < 0.009). There was no significant difference in CK-MB T1 levels between the groups. Although there was no significant difference between CK-MB T1 and T2 levels in the MPSS group, the CK-MB T2 and CK-MB T3 levels were significantly higher than T1 levels in the placebo group (p < 0.001) and (p < 0.05). There was significant elevation of WBC levels at T2 and T3 in both groups without notable difference between the groups (p < 0.05). This study has shown that low-dose MPSS suppresses CPB-induced inflammatory response. Further clinical studies (on larger and higher risk groups) may reveal more information on relations between morbidity and cytokine levels which may have some predictive value on clinical outcome following CPB.
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PMID:Effect of low-dose methyl prednisolone on serum cytokine levels following extracorporeal circulation. 1041 Dec 50

Oral exposure to chlorpyrifos (CHP) in the rat results in an initial hypothermic response followed by a delayed fever. Fever from infection is mediated by the release of cytokines, including interleukin-6 (IL-6) and tumor necrosis factor (TNF alpha). This study determined if the CHP-induced fever involves cytokine-mediated mechanisms similar to that of infectious fevers. Long-Evans rats were gavaged with the corn oil vehicle or CHP (10-50 mg/kg). The rats were euthanized and blood collected at various times that corresponded with the hypothermic and febrile effects of CHP. Plasma IL-6, TNF alpha, cholinesterase activity (ChE), total iron, unsaturated iron binding capacity (UIBC), and zinc were measured. ChE activity was reduced by approximately 50% 4 h after CHP. There was no effect of CHP on IL-6 when measured during the period of CHP-induced hypothermia or fever. TNF alpha levels nearly doubled in female rats 48 h after 25 mg/kg CHP. The changes in plasma cytokine levels following CHP were relatively small when compared to > 1000-fold increase in IL-6 and > 10-fold rise in TNF alpha following lipopolysaccharide (E. coli; 50 microg/kg; i.p.)-induced fever. This does not preclude a role of cytokines in CHP-induced fever. Nonetheless, the data suggest that the delayed fever from CHP is unique, involving mechanisms other than TNF alpha and IL-6 release into the circulation characteristic of infectious fevers.
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PMID:Are circulating cytokines interleukin-6 and tumor necrosis factor alpha involved in chlorpyrifos-induced fever? 1041 84

Experimental studies have demonstrated that postischemic therapeutic interventions may delay rather than provide long-lasting neuroprotection. The purpose of this study was to determine whether mild hypothermia (33-34 degrees C) combined with the anti-inflammatory cytokine interleukin-10 (IL-10) would protect the CA1 hippocampus 2 months after ischemia. Rats were subjected to 12.5 min of normothermic (37 degrees C) forebrain ischemia by two-vessel occlusion followed immediately by: (a) 4 h of normothermic (37 degrees C) reperfusion (n = 5); (b) 4 h of postischemic hypothermia (33-34 degrees C) (n = 5); (c) 4 h of normothermia plus IL-10 (5 micrograms) treatment 30 min after ischemia and at 3 days (n = 5); or (d) 4 h of hypothermia plus IL-10 treatment (n = 5). Rats survived for 2 months and were perfusion fixed for quantitative histopathological assessment of CA1 hippocampus. Postischemic normothermia and hypothermia, as well as normothermia plus IL-10 treatment led to severe damage of the CA1 hippocampus. In contrast, the combined treatment of hypothermia with IL-10 treatment improved overall neuronal survival by 49% compared to normothermic ischemia (P < 0.01). These data emphasize the detrimental consequences of secondary inflammatory responses on ischemic neuronal damage after transient global ischemia. In postinjury settings where restricted durations of mild hypothermia can be induced, anti-inflammatory treatments, including IL-10, may promote chronic neuroprotection.
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PMID:Postischemic hypothermia and IL-10 treatment provide long-lasting neuroprotection of CA1 hippocampus following transient global ischemia in rats. 1041 51

Although sepsis causes significant morbidity and mortality, its basic pathology is still not well understood. We investigated the inflammatory and physiologic alterations of non-lethal sepsis using cecal ligation and puncture (CLP), a model that induces peritonitis due to mixed intestinal flora, reproducing the complex immunology of sepsis. Groups of mice were subjected to CLP (25G needle) or sham surgery, had minimitters implanted to continuously monitor temperature and activity, and were sacrificed daily for 6 days. There was significant hypothermia (6-13 hrs post-surgery), and decreases in activity (to day 4) and weight (to day 3) but no mortality in the CLP group. Blood analyses of the CLP-treated mice showed reduced hemoglobin, platelets, lymphocytes, monocytes, and neutrophils, compared to sham animals. Both groups had nearly equivalent neutrophil influx into the peritoneum. Plasma and peritoneal G-CSF, IL-6, as well as the murine chemokines KC and MIP2-alpha were significantly higher in the CLP-treated mice at day 1. Plasma and peritoneal TNF were low (<70 pg/mL). While there was elevated IL-1beta in the peritoneum of the CLP-treated mice, this cytokine was not detected in the plasma in either treatment group. Cytokines were not detected in the pulmonary airspace of the CLP-treated mice and PMNs were not recruited to this site. Our data shows altered immunopathology in non-lethal sepsis with significant blood and cytokine alterations. Since there was 100% survival, the inflammatory response was appropriate and probably even protective.
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PMID:Immunopathologic responses to non-lethal sepsis. 1044 92

We have demonstrated recently that therapeutic moderate hypothermia of 32-33 degrees C, induced by surface cooling under the administration of narcotics, sedatives and muscle relaxant, suppresses cytokine production after traumatic brain injury. We present here the first documented case report of augmented cytokine production in two accidental hypothermia patients, unconscious 84- (acute immersion) and 87- (non-immersion) year-old women, whose rectal temperatures were below 28 degrees C. The victims were artificially ventilated after sedation with midazolam and buprenorphine in accordance with our protocol. Rewarming at the rate of approximately 1 degrees C/h was done by blowing forced-air with appropriate fluid resuscitation. Plasma interleukin(IL)-6 and/or IL-8 levels were measured using ELISA in the patients. In both patients, plasma IL-6 levels on admission were already elevated and the cytokine levels further increased during and after the rewarming period. In the patient with the poorer prognosis, the plasma IL-8 level on admission was not elevated remarkably but after rewarming the level rose significantly. Augmented IL-6 production in accidental hypothermia was sustained for 6 days in the patient with the poorer prognosis but not in the subject with good recovery, who was treated with anti-thrombin III in the early phase. Since the mechanisms for developing accidental hypothermia were different, simple comparisons between the two cases should be limited. But, these findings may suggest a need for testing a hypothesis whether cytokine modulation could be a therapeutic approach worthy of consideration. The results presented here also suggest that in hypothermia, changes in cytokine release may vary depending on procedures such as the anesthetic drugs used, the duration of the therapy, or the rate of rewarming from hypothermia.
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PMID:Activated cytokine production in patients with accidental hypothermia. 1050 12

Chlorpyrifos (CHP), an OP-based pesticide, induces hypothermia in the rat followed by a fever that persists for several days. The cytokine, tumor necrosis factor-alpha (TNF), is induced by lipopolysaccharide (LPS) and released during fever and has both pyrogenic and cryogenic (i.e. antipyretic) properties. Administering antibodies to TNF (anti-TNF) is known to disrupt fever from infection. Thus, the purpose of this study was to examine whether anti-TNF also disrupts CHP-induced changes in body temperature of the female Long-Evans rat. A positive effect would suggest a role of TNF in the etiology of OP toxicity. In study one, rats were given either saline or anti-TNF (50,000 units, i.p.). Three hours later, animals were given corn oil (CO) or 25 mg/kg CHP by oral gavage in the morning. In study two, rats were given anti-TNF followed by CO or 10 mg/kg CHP in the afternoon. Core temperature and motor activity were monitored continuously by telemetry. In study one, anti-TNF (50,000 units) had no effect on the hypothermic response to 25 mg/kg CHP. However, anti-TNF treated animals maintained higher fevers 3 days (48-96 h post-injection) after CHP treatment. In study two, anti-TNF attenuated the hypothermic response induced by 10 mg/kg CHP but had no effect on the magnitude of the delayed fever. Overall, 25 mg/kg CHP elicited a longer period of hypothermia and delayed fever compared to 10 mg/kg CHP. Anti-TNF pretreatment attenuated the hypothermic response at the lower CHP dose and exacerbated the fever at the higher CHP dose. Anti-TNF also attenuated the hypothermic effect of high doses of LPS and exacerbated LPS-induced fever. These data indicate that endogenously produced TNF is involved in the etiology of CHP mediated hypothermia and fever.
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PMID:Tumor necrosis factor is involved in chlorpyrifos--induced changes in core temperature in the female rat. 1051 30

We investigated inflammatory and physiologic parameters in sepsis models of increasing lethality induced by cecal ligation and puncture (CLP). Mice received imipenem for antibiotic therapy, and groups were sacrificed at 2, 4, 8, 12, 16, 20, and 24 h after CLP. The severity of sepsis increased with needle puncture size (lethality with 18-gauge puncture [18G], 100%; 21G, 50%; 25G, 5%; sham treatment, 0%). While the temperature (at 12 h) and the activity and diurnal rhythm (at day 4) of the 25G-treated CLP group recovered to normal, the 21G and 18G treatment groups exhibited severe hypothermia along with decreased activities. A direct correlation was also observed between the severity of sepsis and cytokine (interleukin 1beta [IL-1beta], tumor necrosis factor [TNF], IL-6, and IL-10) concentrations in both the peritoneum and the plasma. There were substantially higher cytokine levels in the more severe CLP models than in the sham-treated one. Peritoneal and plasma TNF levels were always less than 40 pg/ml in all models. None of the cytokines in the septic mice peaked within the first hour, which is in contrast to the results of most endotoxin models. Chemokine (KC and macrophage inflammatory protein 2) profiles also correlated with the severity of sepsis. Except for the chemokines, levels of inflammatory mediators were always higher at the site of inflammation (peritoneum) than in the circulation. Our study demonstrated that sepsis of increasing severity induced increased cytokine levels both within the local environment (peritoneum) and systemically (plasma), which in turn correlated with morbidity and mortality.
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PMID:Immunopathologic alterations in murine models of sepsis of increasing severity. 1056 81

In the management of severe pediatric brain injury, attention has previously been paid to brain edema, ICP elevation and low cerebral perfusion pressure (CPP). However, in the acute stage within 3-6 hours after trauma, brain hypoxia and hyperglycemia associated with diffuse brain injury are often observed. We have pointed out brain thermo-pooling (elevation of brain tissue temperature) and brain hypoxia caused by defective release of oxygen from hemoglobin (due to decrease in red blood cell enzyme (DPG)) as a new mechanism of brain injury. To treat these pathologic changes, we have developed a brain hypothermia treatment, the major purpose of which is to prevent brain hypoxia, brain thermo-pooling, neurohormonal changes causing cytokine encephalopathy, and a selective, radical-mediated damage of the dopamine A10 nervous system. The brain tissue temperature is initially adjusted to 35 degrees C with adequate cerebral oxygenation, followed by brain hypothermia at 34 degrees C for 1 weeks to prevent brain hypoxia, free radical reactions, brain edema and ICP elevation. What is most difficult in the pediatric brain hypothermia treatment is to maintain metabolic balance in the injured brain tissue and pulmonary infections associated with an immune crisis. When a rapid elevation of serum glucose is noted it is critical to lower the value because glucose quickly penetrates the blood-brain barrier and increases pyruvate and lactate by inhibiting the TCA cycle metabolism. Thus, hyperglycemia during brain hypothermia treatment is one of the major target of management. Another problem is immune crisis associated with secondary pulmonary infections. To prevent them, early enteral nutrition and replacement of L-arginine were most useful, as well as preconditioning for rewarming as follows: serum albumin > 3.0 g/dl; lymphocyte > 1500/mm3; T-H (CD4) lymphocytes > 55%; serum glucose, 120-140 mg/dl; vitamin A > 50 mg/dl; Hb > 12 g/dl and 2,3 DPG, 10-15 mumol/gHb; O2 ER, 23-25% and AT-III, > 100%. The clinical benefit of this therapy is still controversial.
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PMID:[Brain hypothermia treatment for the management of severe pediatric brain injury]. 1072 86


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