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

The implantation and one hour post-transplant renal biopsies from three types of allograft recipients were compared with a blind grading system: (1) 25 cadaver kidneys preserved by pulsatile perfusion, (2) seven cadaver kidneys preserved by simple hypothermia following electrolyte solution flush, (3) 18 kidneys from living-related donors. Significant lesions were found only in cadaver kidneys which had received pulsatile preservation. Microscopic findings were correlated with perfusing agent, length of perfusion and its characteristics, and subsequent clinical course of the patient. Perfusion-related injury was found to be morphologically identical to hyperacute rejection, although the lesion is produced by quite different mechanisms. Pulsatile preservation appears to be associated with a spectrum of mechanical endothelial injury ranging from minute breaks visible only ultrastructurally to areas of complete denudation baring the basement membrane. The exposed collagen activates the clotting sequence resulting in platelet and fibrin deposition, whereas in classical hyperacute rejection the triggering mechanism is cytotoxic recipient antibody. The extent of perfusion-related injury correlates well with length of preservation, quantity of fibrin deposited, and, most importantly, with both the immediate and long-term post-transplant failure rate. In some patients the injury appears to be produced by cytotoxic antibodies in the plasma perfusate, which combine with antigens in the kidney ex vivo. The Ag-Ab complex activates complement and coagulation sequences in vivo after reimplantation. Early results with albumin or purified plasma fraction perfusates suggest this portion of perfusion-related injury can be eliminated. Comparison of pre- and postimplantation biopsies of the kidneys preserved by simple hypothermia or by pulsatile preservation suggests that perfusion-related injury is much more common than is true hyperacute rejection mediated by recipient cytotoxic antibodies. We suggest that the term "hyperacute rejection" be reserved for situations where significant endothelial drainage has been excluded by preimplantation biopsy and where recipient cytotoxic antibodies can be proved.
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PMID:Perfusion-related injury in renal transplantation. 76 23

Potential morbidity remains substantial in aortic root replacement. The tissues are often fragile, contributing to the risk of haemorrhage and postoperative complications. In the past surgery has been directed towards minimising haemorrhage by wraparound techniques and the right atrial fistula method of Cabrol. However, recent use of aortic homografts, collagen-impregnated grafts and tissue glues have reduced bleeding and simplified operative technique. Profound hypothermia and total circulatory arrest allows aneurysm resection to extend into the aortic arch. Between 1986 and 1991 25 aortic root replacements were carried out at the Oxford Heart Centre in 21- to 76-year-olds, 13 for aorto-annular ectasia (4 due to Marfan's syndrome), 7 for aortic dissection (2 Marfan's syndrome) and 2 for complications of previous aortic valve replacement. Three patients had homograft root replacement for aortic root endocarditis. We implanted 14 Medtronic composite grafts, 1 St Jude conduit and 7 collagen-coated Dacron grafts (Hemashield, Meadox) into which a Starr-Edwards valve was sewn, as well as 3 homografts. One patient with a massive chronic dissection following previous aortic valve replacement required an interposition graft to the coronary ostia. In the others, the coronary ostia were mobilised from the native aorta and directly implanted into the conduit. In dissections a ring of pericardium or GoreTex was used to buttress the coronary anastomoses. Six patients also required coronary artery grafting. Native aorta was excised and not wrapped around the conduit. Coagulation defects were corrected aggressively with platelets, fresh frozen plasma and cryoprecipitate.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Aortic root replacement: modifications of technique with improvements in technology. 138 78

In the feline intestine studies have implicated superoxide (O.-) and other oxygen derived free radicals as initiators of injury as measured by increased capillary permeability during the reperfusion period. Biochemical mechanisms of this free radical generation include: xanthine oxidase dependent O.- production, hydrogen peroxide (H2O2) formation by superoxide dismutase (SOD), hydroxyl radical (OH-) production via the Haber-Weiss reaction, and lipid radical formation from membrane peroxidation. Pathological consequences of these events include inflammatory neutrophil infiltration, damage to the collagen and mucosal basement membrane, increased capillary permeability, edema, cell degeneration and necrosis. Animal models of neonatal necrotizing enterocolitis (NNEC) indicate that intestinal injury occurs after the etiologic factors (hypothermia, hypoxia) are removed. In order to determine the role of active oxygen species in the pathogenesis of NNEC, weanling hamsters and neonatal piglets were cold stressed and activities of pro/antioxidant enzymes were determined, and histopathologic and ultrastructural studies were performed. Cold stressed weanling hamsters showed a 55.7% (P less than 0.05) decrease in xanthine dehydrogenase/xanthine oxidase activity ratio. Light microscopy revealed scattered colonic mucosal erosions and submucosal edema in 50% of cold stressed animals. Transmission electron microscopy demonstrated degeneration of colonic mucosal epithelial cells, enlarged intracellular spaces, cytoplasmic vacuolization, and nuclear membrane swelling. The colonic serosa was also edematous and infiltrated with bacteria. Large intestinal tissue from cold stressed neonatal piglets showed a significant increase (P less than 0.05) in Mn and Cu, Zn, SOD, CAT, GSH-Red, total GSH, and Glc6-PD at 0 and 12 hrs. post stress.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Intestinal post-ischemic reperfusion injury: studies with neonatal necrotizing enterocolitis. 259 24

The authors describe a patient who presented from birth on a severe involvement of connective tissues with pathological fractures, lack of auricular cartilage, hyperlaxity of fingers and cutis laxa with deep folds, all suggestive of derangements of collagen and elastin. Hypothermia at 24 hours of age should have already indicated the possibility of Menkes' syndrome. From the 3rd month on, the patient presents a neurological deterioration and a myoclonic epilepsy which is resistant to treatment. Craniocerebral tomodensitometry revealed, with time, a cerebral atrophy and subdural hematomas. Angiodysplasia of a coronary artery was seen at cardiac echocardiography. Undetectable levels of serum copper and ceruloplasmin, and an increased uptake of copper by fibroblasts in vitro confirmed the diagnosis of Menkes' syndrome. Electron microscopy of a skin biopsy disclosed a desmosomal anomaly in the epidermis. Desmosomes stay apart suggesting an alteration of the interdesmosomal cement.
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PMID:[Menkes disease. Report of a case with pronounced involvement of connective tissues and changes in epidermal desmosomes]. 270 74

Changes in fibrinolysis, platelets and coagulation during hypothermia were investigated in anesthetized dogs. Strong activation of plasma fibrinolysis was observed in the hypothermia group. The maximum fibrinolytic activity determined with standard fibrin plates was markedly higher than that of the control sample (mean values: 67 and 15 mm2/0.03 ml plasma, respectively). On the other hand, no fibrinolysis was observed by the plasminogen free plate method. Activation was not observed in the control group or the hypothermia group premedicated with chlorpromazine. The platelet count was decreased from 100% to 14.7% and the collagen induced platelet aggregability from 61% to 2.3% during hypothermia. Recovery from both reductions occurred on rewarming. In the control and premedicated groups, the recalcification time was reduced progressively (from 93.6 to 60.9 sec and from 101.1 to 71.8 sec as mean times, respectively). The tendency towards shortening of the recalcification time was not related to the core temperature.
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PMID:Changes in coagulation and fibrinolysis occurring in dogs during hypothermia. 398 6

A number of hemostasis parameters were studied in a total of 63 patients undergoing cardiopulmonary bypass (CPB) for open heart surgery. In 33 patients fibrinogen, Factors II, V, VIII:C, X, XI, antithrombin, plasminogen, alpha 2-antiplasmin, and platelet counts were assayed before surgery, during maximal hypothermia, at the end of the bypass procedure, before and after protamine sulfate infusion, in the intensive care unit, and 48 hours postoperatively. All factors assayed decreased markedly when the patients were placed on the bypass machine, the drop fairly well paralleling the decrease in hematocrit. During bypass the factors remained low, although a slight tendency toward an increase was noted. Only platelet counts remained low with a decreasing trend until the end of bypass. In the intensive care unit a second decrease in fibrinogen, Factors II and V and antithrombin was noted. This drop was unrelated to four patients who experienced a greater blood loss during this time than the others. Forty-eight hours postoperatively, a marked increase could be found in all clotting factors and near normal levels were measured. Platelet counts remained low, however. The decrease in factors rarely dropped into a range where one would expect a compromised hemostasis (less than 30%). Although antithrombin levels decreased below 60%, no difficulties with heparinization were encountered. Several factors were assayed manually and by automated analyzer (Multistat III), and excellent correlations were found between both procedures. Also a good correlation was found between the activated whole blood clotting times and quantitative heparin assays. In 30 additional patients platelet function was studied before surgery, after thoracotomy, after heparin administration, after initiation of bypass, at maximal hypothermia, before and after protamine sulfate infusion, and 24 hours postoperatively. Platelet counts once again decreased as patients were placed on the CPB machine and remained low throughout the procedure. Mean platelet volumes were unchanged until protamine was given. At that time, a significant drop in mean platelet volume was recorded. Twenty-four hours postoperatively the volumes were normal again. Platelet aggregation studies were performed on a whole blood aggregometer using two concentrations of ADP, collagen, and ristocetin as aggregation inducers. A significant decrease in aggregability was seen when the patients were connected to the CPB apparatus.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Hemostasis changes during cardiopulmonary bypass surgery. 404 52

The effects of high-energy shock waves (HESW) on the human renal cell carcinoma were examined. The kidneys were available from 32 patients treated by radical nephrectomy due to renal cell carcinoma. Immediately after nephrectomy the kidneys were perfused with cold HTK solution and stored for a maximum of 4 h in hypothermia at 8 degrees C. The tumors were treated with 4,000 shocks (65 mPa = 0.6 mJ/mm2) in an electromagnetic lithotriptor (Siemens Co., Erlangen, Germany). Microscopic and immunohistological examinations of the tumors were performed after treatment, and cell proliferation rates of treated and untreated specimens were analyzed by cell cultures in 10 cases. HESW induce severe microscopic damage in the tumor tissue as complete rupture of the vessel walls and destruction of the tubular-formed tumor masses in the focal area. Immunohistochemistry shows intact immune reactive endothelial cells by factor 8-associated antibodies until the border to histological damage. Around this region a zone of negative antibody reaction against collagen type 4 is found. In cell cultures the proliferation rates of treated specimens were significantly lower compared to untreated. The human renal cell carcinoma seems to be susceptible for treatment with shock waves. HESW induce direct damage of tumor cells and vascular damage in the tumor which may be the primary cause of tumor necrosis.
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PMID:Treatment of human renal cell carcinoma with high-energy shock waves--a new in vivo/in vitro model. 757 Nov 74

To increase the storage time of livers for transplantation, a better understanding of hypothermia-induced hepatocyte damage is necessary. To this end, we have characterized the effects of hypothermia on long-term function and cytoskeletal organization of hepatocytes cultured in the collagen sandwich configuration, which maintains the expression of liver-specific functions for several weeks. In these studies, cultured hepatocytes (maintained at 37 degrees C for 7 days) were exposed to 4 degrees C in Leibovitz-15 (L15), University of Wisconsin (UW) solution, or L15 supplemented with 2.5 g% polyethylene glycol (PEG) for various time periods followed by a return to normothermia. When L15 medium was used, the long-term albumin secretion rate of cultured hepatocytes was decreased by 50% after 4 h, and by 95% after 24 h of exposure to 4 degrees C. Amorphous precipitates of F-actin and fragmented short microtubules were also observed after 4 and 12 h of hypothermia, respectively. Similar results were obtained when hepatocytes were stored in UW solution. However, in L15 supplemented with PEG, no significant reduction in long-term albumin secretion rates and intact actin and microtubule morphology was observed even after 24 h of exposure to 4 degrees C. The membrane integrity and long-term albumin secretion of hepatocytes stored in the presence of PEG were decreased to approximately 50% only after 48 h of exposure to 4 degrees C. Thus, PEG may be a useful additive in preservation solutions for hepatocytes in hepatocyte-based liver support systems and for intact tissue as well.
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PMID:Effects of hypothermia on the function, membrane integrity, and cytoskeletal structure of hepatocytes. 765 72

Hypothermic cardiopulmonary bypass (CPB) has been associated with both coagulation defects and hemorrhage. The influence of temperature on platelet function and the benefits of aprotinin in this situation were studied in 60 patients undergoing elective aortocoronary bypass grafting. The patients were randomly divided into four groups (15 patients per group): group 1, normothermic CPB (nasopharyngeal temperature > 34 degrees C); group 2, normothermic bypass and administration of high-dose aprotinin (2 million IU before CPB, 500,000 IU/h until the end of the operation, and 2 million IU added to the prime); group 3, hypothermic CPB (nasopharyngeal temperature < 28 degrees C); and group 4, hypothermic CPB and aprotinin. Platelet function was evaluated by aggregometry (turbidimetric technique), and aggregation was induced by adenosine diphosphate (1 and 2 mumol/L), collagen (4 micrograms/L), and epinephrine (25 mumol/L) before, during, and after CPB into the first postoperative day. Starting from comparable baseline values, maximum platelet aggregation and maximum gradient of platelet aggregation were significantly most reduced after CPB in group 3 (hypothermic CPB without aprotinin) (ranging from -30% to -53% relative to baseline values). In comparison with the other groups, platelet function in this group also recovered less quickly in the later post-bypass period. Hypothermic CPB with aprotinin resulted in less-altered platelet function than hypothermic CPB without aprotinin. Platelet aggregation in aprotinin-treated patients was comparable overall with that in patients undergoing normothermic CPB. On the first postoperative day, aggregation variables had returned to or exceeded baseline values.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Platelet function in cardiac surgery: influence of temperature and aprotinin. 750 60

We have experienced graft replacement of a thoracic aortic aneurysm in a 42-year-old man with Ehlers-Danlos syndrome. The patient received graft replacement of the abdominal aortic aneurysm 1 year before this thoracic operation but had no abnormality in his outside appearance. Thoracic CT scan revealed a thoracic aortic aneurysm of 80 mm in maximal diameter. We performed a graft replacement of the thoracic aorta from the ascending aorta to the proximal descending thoracic aorta using deep hypothermia and retrograde cerebral perfusion. The aortic wall was so thin that we used Teflon felt for reinforcement of graft anastomosis at the outside wall of the aortic stump. Type III collagen stain of the resected aortic wall showed deficiency of type III collage, which was consistent with Ehlers-Danlos syndrome (type IV). Postoperative course was uneventful, and the patient returned to his ordinary life.
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PMID:[Successful graft replacement of a thoracic aortic aneurysm in a patient with Ehlers-Danlos syndrome]. 852 72


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