Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0020672 (hypothermia)
 17,327 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hepatocytes from isolated rat livers were hypothermically incubated (5 degrees C) in an oxygenated environment with continuous shaking (to simulate organ perfusion preservation). The incubation solution was either a tissue culture medium (L-15), an organ preservation perfusate (UW gluconate), or a simple cold-storage solution used for organ preservation (UW lactobionate). Hepatocyte viability was assessed from the release of lactate dehydrogenase (LDH) into the incubation medium. Cell swelling (due to the uptake of water) was also measured. Within 24 hr, hepatocytes hypothermically stored in each of the three incubation solutions became swollen (30 to 40% water gain) and lost a significant amount of LDH (as much as 60%). The addition of polyethylene glycol (PEG; relative molecular mass 8000; 5 g%) to the solutions suppressed cell swelling and allowed the incubated hepatocytes to remain relatively well preserved (30% LDH release) for as long as 120 hr. Adding either dextran (relative molecular mass 10,000 to 78,000; 5 g%) or saccharides (100 mmol/liter) instead of PEG neither prevented cell swelling nor prevented the cells from dying. The results of this study suggest (i) there is a direct correlation (r = 0.873) between hypothermia-induced cell swelling and cell death (i.e., the suppression of cell swelling prevents cell death); (ii) the mechanism by which PEG prevents cell swelling (and thus maintains cell viability) is not related to the osmotic or oncotic properties of the molecule but instead is apparently related to some unknown interaction between PEG and the cell, an interaction that provides stability during hypothermic incubation; and (iii) hypothermia-induced cell swelling must be prevented if isolated hepatocytes are to be used as a model for studying the mechanism by which cell damage occurs during hypothermic organ preservation. By eliminating cell death due to cell swelling, the biochemical mechanisms of cell death can be studied.
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PMID:Hypothermic preservation of hepatocytes. I. Role of cell swelling. 248 Aug 65

The release of oxygen free radicals from ischemic myocardium has been implicated as a causative factor of cardiac dysfunction after thermal injury. In this study, isolated coronary perfused guinea pig hearts were used to determine if free radical scavengers improve left ventricular (LV) intrinsic contractile response to burn shock. Parameters measured included peak isovolumic LV pressure (LVP) and maximal rate of LVP rise (+dP/dtmax) and fall (-dP/dtmax) at a constant preload. Control animals were immersed in body temperature water and divided into four groups: Group 1, untreated N = 10; Group 2, control animals treated with unbound superoxide dismutase (SOD), N = 5; Group 3, control animals treated with ficoll-SOD, N = 5; and Group 4, control animals treated with PEG-SOD, N = 5. Scald burn equivalent to 45% of total body surface area was produced in 64 animals. Fluid resuscitation was initiated immediately after burn in all animals, and animals were then divided into seven burn experimental groups. In Group 5, 10 animals were treated with fluid alone, lactated Ringer's, 4 mL/kg/% burn. Burned animals in Group 6 (N = 10) received a reduced volume of Ringer's 2 mL/kg/% burn plus unbound-SOD, 50 mg/kg; 10 animals in Group 7 received this volume of Ringer's plus ficoll-SOD, 50 mg/kg. In groups 8, 9, and 10 animals were given fluid, lactated Ringer's, 2 mL/kg/% burn plus varying doses of PEG-SOD (Group 8: N = 9, 1,000 U; Group 9: N = 10, 6,000 U; Group 10: N = 5, 12,000 U). In Group 11 (N = 10), animals received SOD-PEG, 6,000 U, plus catalase, CAT-PEG, 6,000 U, given with 4 mL/kg/% burn lactated Ringer's solution. Hypotension, hypothermia, and hemoconcentration were similar in all animals after thermal injury, regardless of treatment regimen. Burn hearts showed significantly lower LVP, +dP/dt max, and -dP/dt max than control hearts (P less than 0.05). Compared to controls, coronary pressure and coronary vascular resistance were significantly higher in all treated burn groups. There was no significant difference in heart rate or time to peak pressure or time to maximal contraction or relaxation among the groups. Left ventricular function curves for burned hearts were shifted downward and to the right of curves obtained from control hearts (P less than 0.01), regardless of scavenger treatment. PEG-SOD, 6,000 U, improved left ventricular contractility (+dP/dt) at maximal levels of end-diastolic pressure but deficits in left ventricular pressure and relaxation persisted.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:The role of oxygen-derived free radicals in burn-induced myocardial contractile depression. 322 Aug 65

Hypothermic cardiopulmonary bypass alters platelet function and hypothermia is associated with postoperative myocardial ischemia. Thrombogenic surfaces such as extracorporeal circuits, vascular graft materials, and components of atherosclerotic plaque induce activation of platelets. The effects of human hemoglobin (Hb) covalently modified to carry S-nitric oxide (NO) functional groups (SNO-Hb), polyethylene glycol (PEG-Hb), and SNO-PEG-Hb on platelet activation were studied. Platelet activation was assessed by cytometric analysis of GPIIb-IIIa activation and P-selectin expression at hypothermic condition (22 degrees C) after stimulation with Hb derivatives. Platelet adhesion and aggregation were measured in a parallel glass plate chamber coated with unmodified Hb, SNO-Hb, PEG-Hb, SNO-PEG-Hb, and collagen. Platelet binding of antibodies to GPIIb-IIIa and P-selectin was significantly enhanced by hypothermic condition and by unmodified Hb. There was significantly less platelet binding of antibodies to GPIIb-IIIa and P-selectin with SNO-Hb, PEG-Hb, and SNO-PEG-Hb compared with unmodified Hb. There was significantly less platelet attachment, adhesion, and aggregation on the SNO-Hb, PEG-Hb and SNO-PEG-Hb coated surfaces compared with unmodified Hb-coated and -uncoated surfaces. SNO-Hb, PEG-Hb, and SNO-PEG-Hb induced less platelet activation at hypothermic temperature, and induced less platelet adhesion and aggregation on thrombogenic surfaces compared with unmodified Hb. The inhibitory effect may be derived from antiadhesive properties of Hb, antiplatelet actions of NO, and molecular barrier action of PEG.
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PMID:Attenuation of hypothermia-induced platelet activation and platelet adhesion to artificial surfaces in vitro by modification of hemoglobin to carry S-nitric oxide and polyethylene glycol. 1115 32

Preservation of the heart for transplantation after infusion of cardioplegia and extirpation of a cardiac allograft results in an ischemic insult to the myocardium. This ischemic insult may lead to a loss of function in the transplanted heart. Hypothermic perfusion preservation with an oxygen hemoglobin carrying solution may avert ischemic injury and lead to improved recovery of cardiac function. The purpose of this study was to compare cardiac function after 8 hours of continuous hypothermic perfusion with a unique polyethylene-glycol-hemoglobin (PEG-Hb) solution to hearts preserved by 4 hours of hypothermic ischemic storage. Freshly extirpated hearts served as functional controls. The hearts of 26 anesthetized and intubated New Zealand white rabbits were harvested after cold cardioplegic arrest. Group I (n = 12) hearts were perfused with a PEG-Hb solution at 20 degrees C and 30 mm Hg for 8 hours. PO2 was maintained > or = 500 mm Hg. Group II (n = 7) hearts were preserved by cold ischemic storage for 4 hours at 4 degrees C. Group III (n = 7) were tested immediately after harvest. Left ventricular (LV) function was measured in the nonworking state at 15 minutes, 1 hour, and 2 hours after transfer to a standard crystalloid Langendorff circuit. Measurement of LV developed pressure, peak + dP/dt and -dP/dt revealed a superior trend between Group I and Group II hearts in comparison with freshly extirpated hearts. Heart rate was similar among all groups throughout testing (p = ns). Coronary blood flow was not significantly different between groups. Continuous perfusion preservation of rabbit hearts for 8 hours with PEG-Hb solution at 30 mm Hg and 20 degrees C yielded LV function that was similar to 4 hours of ischemic hypothermic storage. Furthermore, return of cardiac function after 8 hours of perfusion preservation using this PEG-Hb solution may be superior to that obtained in freshly extirpated hearts. These data suggest that some recovery of myocardial function may occur during perfusion preservation with this PEG-Hb solution after the ischemic insult of cardioplegic arrest. Continuous perfusion preservation using this PEG-Hb solution deserves further investigation in large animal transplant models.
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PMID:Recovery of cardiac function after standard hypothermic storage versus preservation with Peg-hemoglobin. 1137 56

Renal preservation at for 24 hours at hypothermia was studied in a rabbit model after flush cooling with sucrose-based solution (SBS), compared with a standard preservation solution (in this case, Marshall's Hypertonic Citrate solution - HCA). Polyethylene glycol supplementation to SBS (SBS-PEG) was also investigated. Renal function was measured by plasma creatinine assays during 1 months post transplantation, and pathology of the explanted kidneys was undertaken. Results showed that survival at 28 days was similar in all groups, (HCA - 3 out of 6; SBS - 2 out of 5; SBS-PEG - 3 out of 5), and there were no differences in recovery of plasma creatinine values. Histopathological evaluation of the grafts indicated that SBS preservation resulted in more severe damage after transplantation (P less than 0.05 in both corticomedullary region and medulla compared to HCA), whilst addition of PEG reduced the damage score to that seen with HCA. SBS can be used as a simple, inexpensive preservation solution for kidney cold storage provided that PEG is used as an additional colloid.
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PMID:Hypothermic renal preservation with a sucrose/ polyethylene glycol solution in a rabbit renal transplant model. 1679 44