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Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Infusing pigs with lipopolysaccharide (LPS) decreases superior mesenteric artery blood flow (Qsma), suggesting that mesenteric hypoperfusion may be responsible for LPS-induced alterations in gut mucosal permeability. To test this hypothesis, we studied four groups of anesthetized swine. Group 1 animals (N = 6) were infused with LPS (250 micrograms/kg over 1 hour beginning at 60 minutes) and continuously resuscitated with Ringer's lactate (48 mL/kg per hour). In group 2 (N = 5), Qsma was decreased by 50% by means of a mechanical occluder to mimic the LPS-induced alterations in Qsma observed in group I. Group 3 (N = 5) was included to document our ability to detect ischemia/reperfusion-induced alterations in mucosal permeability; in these pigs, Qsma was decreased in steps to zero flow (at 150 to 210 minutes) and then perfusion was restored (at 210 to 270 minutes). Pigs in group 4 (N = 6) served as normal controls; these animals were resuscitated with Ringer's lactate at the same rate as in group 1 but were not infused with LPS. To assess mucosal permeability, we measured plasma-to-lumen clearances for two markers, chromium 51-labeled edetic acid monohydrate (EDTA) and urea. Loading and maintenance infusions of the markers were given intravenously, and a 20-cm isolated segment of small intestine was continuously perfused at 2 mL/min with Ringer's lactate at 37 degrees C. Results were expressed as the ratio of the clearances for the two probes (CEDTA/CUREA). In group 3, CEDTA/CUREA was 999% +/- 355% of baseline at 270 minutes. In group 1, CEDTA/CUREA was 572% +/- 235% of baseline at 270 minutes. In groups 2 and 4, however, CEDTA/CUREA did not change significantly from the baseline value over the duration of the study. These data suggest that increased mucosal permeability after LPS is due to factors other than (or in addition to) mesenteric hypoperfusion.
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PMID:Increased intestinal permeability in endotoxic pigs. Mesenteric hypoperfusion as an etiologic factor. 189 58

Propionyl-CoA is formed principally during amino acid catabolism. It is then converted chiefly to succinate in a described three-step sequence. Free propionate is formed from propionyl-CoA to a very limited extent, but this anion can participate in a futile cycle of activation and hydrolysis, which can significantly deplete mitochondrial ATP. Free CoA and propionyl-CoA cannot enter or leave mitochondria, but propionyl groups are transferred between separate CoA pools by prior conversion to propionyl-L-carnitine. This reaction requires carnitine and carnitine acetyl transferase, an enzyme abundant in heart tissue. Propionyl-L-carnitine traverses both mitochondrial and cell membranes. Within the cell, this mobility helps to maintain the mitochondrial acyl-CoA/CoA ratio. When this ratio is increased, as in carnitine deficiency states, deleterious consequences ensue, which include deficient metabolism of fatty acids and urea synthesis. From outside the cell (in blood plasma), propionyl-L-carnitine can either be excreted in the urine or redistributed by entering other tissues. This process apparently occurs-without prior hydrolysis and reformation. It is suggested that heart tissue utilizes such exogenous propionyl-L-carnitine to stimulate the tricarboxylic acid cycle (via succinate synthesis) and that this may explain its known protective effect against ischemia.
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PMID:Propionyl-L-carnitine: biochemical significance and possible role in cardiac metabolism. 203 69

These experiments examine the transfer of urea, sodium, and sucrose from blood to brain in an animal model of newborn cerebral ischemia-reperfusion injury. Cerebral ischemia (20 min) was produced in anesthetized, ventilated piglets by increasing intracranial pressure above mean arterial blood pressure, thereby reducing cerebral perfusion pressure to zero. The blood to brain transfer of urea, sodium, and sucrose was then measured in sham control piglets and at 30 min and 2 hr of reperfusion following ischemia. At 30 min of reperfusion, urea and sodium transfer were increased while sucrose transfer was unchanged. However, at 2 hr of reperfusion, transfer of all three tracers was elevated. The difference in the time course of increased transport of these substances into the brain following ischemia cannot be explained by size differences, indicating that changes in the blood-brain barrier following ischemia are more complex than merely opening junctions between cells and creating leaky sites. Alterations in blood-brain barrier transport could participate in altered neuronal function after ischemia-reperfusion injury.
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PMID:Blood to brain transport after newborn cerebral ischemia/reperfusion injury. 206 19

We hypothesized that xanthine oxidase (XO)-derived hydrogen peroxide (H2O2) contributes to ischemic skeletal muscle injury during reperfusion. We found that after ischemia (3 h) and then reperfusion (4 h) rat gastrocnemius muscles had decreased contractile function following direct stimulation. Three lines of investigation suggested that XO-derived H2O2 contributes to reperfusion injury of ischemic skeletal muscle. First, treatment with dimethylthiurea (DMTU), a highly permeant O2 metabolite scavenger, but not urea, just before reperfusion improved muscle function in legs subjected to ischemia and then reperfusion. Second, gastrocnemius muscles from rats fed tungsten or allopurinol had negligible XO activities and increased muscle function after ischemia and reperfusion. Third, as assessed by measurement of skeletal muscle catalase activity in the presence of aminotriazole, H2O2 was measured during reperfusion of ischemic muscles from untreated or urea-treated rats but not during reperfusion of muscles from rats treated with DMTU, tungsten, or allopurinol.
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PMID:Xanthine oxidase-derived H2O2 contributes to reperfusion injury of ischemic skeletal muscle. 211 Jul 80

Calcium is believed to be responsible for initiating a deleterious cascade of events that leads to irreversible cell injury during prolonged ischemia. Theoretically, the calcium-dependent cascade of events can be interrupted at three distinct points: a) by reducing calcium inflow into the cytosol using a calcium channel blocker such as verapamil, b) by increasing the mitochondrial capacity to sequester calcium using ethane-1-hydroxy-1:1-diphosphonic acid (EHDP), and c) by inhibiting the activation of the calcium-calmodulin complex using trifluoperazine (TFP). To evaluate the protective role of these agents in prolonged ischemia, 190 unilaterally nephrectomized rats underwent total occlusion of the renal artery for 90 min. One hour before surgery, all the rats received an i.p. injection of either saline or one of the drugs. Of the 190 rats, 130 were used to determine survival and optimal drug doses; the remaining 60 rats were used to determine blood urea nitrogen and serum creatinine at 40 h and 5 days after surgery. Only 33% of the rats in the control group survived for 10 days. However, 87.5% (P less than 0.005), 90% (P less than 0.005), and 60% (P less than 0.01) of the rats pretreated with verapamil, TFP and EHDP respectively survived for 10 days. No differences, however, were seen in renal function tests among the control, TFP or EHDP groups. This suggests that calcium antagonists are successful in protecting the kidney from prolonged ischemic injury despite impaired renal function tests. It may also indicate that these agents delay or prevent the ischemic cells from undergoing irreversible damage.
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PMID:Blocking the calcium cascade in experimental acute renal failure. 211 82

We assessed the effect of 1,3-butanediol on cerebral energy metabolism and edema after inducing multifocal brain infarcts in 108 rats by the intracarotid injection of 50-microns carbonized microspheres. An ethanol dimer that induces systemic ketosis, 25 mmol/kg i.p. butanediol was injected every 3 hours to produce a sustained increase in the plasma level of beta-hydroxybutyrate. Treatment significantly attenuated ischemia-induced metabolic changes by increasing the concentrations of phosphocreatine, adenosine triphosphate, and glycogen and by reducing the concentrations of pyruvate and lactate. Lactate concentration 2, 6, and 12 hours after embolization decreased by 13%, 44%, and 46%, respectively. Brain water content increased from 78.63% in six unembolized rats to 80.93% in 12 saline-treated and 79.57% in seven butanediol-treated rats 12 hours after embolization. (p less than 0.05). The decrease in water content was associated with significant decreases in the concentrations of sodium and chloride. The antiedema effect of butanediol could not be explained by an osmotic mechanism since equimolar doses of urea or ethanol were ineffective. Our results support the hypothesis that the beneficial effect of butanediol is mediated through cerebral utilization of ketone bodies arising from butanediol metabolism, reducing the rate of glycolysis and the deleterious accumulation of lactic acid during ischemia.
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PMID:Beneficial effect of 1,3-butanediol on cerebral energy metabolism and edema following brain embolization in rats. 221 11

Recently we reported that maintaining rats on restricted dietary protein regimens prior to renal ischemia will significantly improve postischemic survival rates. This effect required a week or more of maintenance on a restricted protein diet prior to the renal insult and appeared to be independent of the postischemic dietary protein regimen. The present study was designed to evaluate the role of systemic toxicity in this protection. Adult male Sprague-Dawley rats were pair-fed by weight on restricted or high isocaloric protein diets for 8-10 days prior to 45 min of renal ischemia induced by renal pedicle clamping. When placed on a normal dietary protein regimen immediately following ischemia, the rats preconditioned to restricted dietary protein exhibited significantly less acidosis, less hyperkalemia, lower blood urea nitrogen values, and improved survival rates compared with rats preconditioned on a high dietary protein regimen. In order to separate the possible effects of prior dietary protein regimen on acute tubular necrosis suffered during renal ischemia from its effects on the uremic response, bilateral nephrectomies were performed on rats preconditioned for 14 days to low, normal, and high dietary protein regimens. Although all of the rats were placed on the same dietary protein regimen immediately following bilateral nephrectomy, those that had previously been on a lower dietary protein regimen exhibited a significantly reduced uremic response and lived longer. These findings indicate that dietary protein regimen prior to renal ischemia is a risk factor which can have a significant lingering effect on the severity of postischemic systemic toxicity.
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PMID:Dietary protein regimen prior to renal ischemia significantly affects the postischemic uremic response. 237 Sep 27

Normothermic ischemia tolerance is an important aspect of organ procurement and transplantation. The function of pancreas and kidney autografts was investigated in totally pancreatectomized or nephrectomized canine recipients. In 30 dogs the left limb (tail) of the pancreas was removed but left in the abdominal cavity after cessation of blood flow to produce warm ischemia for 30, 60, and 120 min (10 dogs at each time point), and then was flushed with cold Ringers' lactate and transplanted to the iliac vessels. Twenty dogs with fresh pancreatic transplants were controls. The success rate of pancreas transplants with warm ischemia of 1/2 and 1 hr was the same as that of controls (80%); however, after 1 hr normothermia 5/10 dogs had episodes of hyperglycemia for 1 week before glucose levels came back to normal. All but one graft with 2 hr warm ischemia failed. Intravenous glucose tolerance test (IVGTT) mean (+/- SEM) K values were not different in the successful groups, i.e., no warm ischemia: -1.55 +/- 0.15%; 1/2 hr warm ischemia: -1.81 +/- 0.18%; 1 hr warm ischemia: -1.64 +/- 0.09%. Amylase levels increased after transplant with maximum values at Day 2, then returned to normal, but the levels remained elevated in recipients of grafts subjected to longer normothermia with evidence of pancreatitis after 1 hr warm ischemia. Fifteen kidney grafts were treated similarly with warm ischemia exposure of 1/2 hr (n = 9) and 1 hr (n = 6) before being flushed and autotransplanted, and were compared to 16 fresh kidney transplants. After 1/2 hr warm ischemia none of the kidney grafts failed but 78% of the recipients had elevated serum creatinine and urea nitrogen levels which returned slowly to normal after 3 to 4 weeks. There was only one long-term survivor after 1 hr warm ischemia. Thus the pancreas seems to be more resistant to warm ischemia damage than is the kidney. This difference should be taken into consideration in regard to organ procurement for clinical transplantation.
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PMID:Definition of normothermic ischemia limits for kidney and pancreas grafts. 242 97

To determine the timing and location of renal cell regeneration after ischemic injury to the kidney and to assess whether exogenous epidermal growth factor (EGF) enhances this regenerative repair process to accelerate recovery of renal function, experiments were undertaken in rats undergoing 30 min of bilateral renal artery clamp ischemia followed by reperfusion for varying time intervals. Renal cell regeneration, as reflected by incorporation of radiolabeled thymidine within the kidney, began between 24 to 48 h and reached a peak at 72 h after renal ischemia. As demonstrated by histoautoradiography, renal thymidine incorporation was essentially confined to tubule cells. Morphometric analysis of histoautoradiograph sections of renal tissue demonstrated that the majority of labeled cells were found in renal cortex, but some labeled cells were also located in the inner stripe of the outer medulla, suggesting that injury to medullary thick ascending limbs also occurs in this ischemic model. Exogenous EGF administration produced increases in renal thymidine incorporation compared with non-treated animals at 24, 48, and 72 h after ischemic injury. This accelerated DNA replicative process was associated with significantly lower peak blood urea nitrogen (BUN) and serum creatinine levels, averaging 63 +/- 20 and 3.1 +/- 0.4 mg/dl in EGF-treated ischemic rats compared with 149 +/- 20 and 5.1 +/- 0.1 mg/dl, respectively, in nontreated ischemic rats, and was also associated with a return to near normal BUN and serum creatinine levels in EGF-treated animals approximately 4 d earlier than that observed in nontreated animals. This report is the first demonstration that EGF accelerates the repair process of a visceral organ after an injurious insult.
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PMID:Epidermal growth factor enhances renal tubule cell regeneration and repair and accelerates the recovery of renal function in postischemic acute renal failure. 259 59

A previous article (Part I) described the patient population and operative management of 666 patients who had surgery for nonruptured abdominal aortic aneurysms. This article details the perioperative complications and, by chi-square and logistic regression analysis, identifies the variables that are associated with each complication. In summarizing the results (below) the incidence of each complication is listed, along with the predictive risk factors in parentheses that have significance levels less than 0.05. Vascular morbidity data are as follows: intraoperative bleeding, 4.8%; postoperative bleeding requiring transfusion, 2.3% or repeat operation, 1.4% (large volume of blood transfusion and/or use of an autotransfusion device); intraoperative limb ischemia, 3.5%; graft thrombosis, 0.9% (femoropopliteal disease and/or distal anastomosis at the femoral level); distal thromboembolism, 3.3% (male sex, femoral popliteal disease, and/or intraoperative graft thrombosis); amputation, 1.2%; graft infection, 1 case. General morbidity data are as follows: cerebrovascular event, 0.6%; paraplegia, 1 case; cardiac event, 15.1% (age, previous episode of congestive heart failure, and/or electrocardiogram [ECG] evidence of a previous myocardial infarction); myocardial infarction, 5.2% (advancing age, angina, and/or prolonged aortic cross-clamp time); congestive heart failure, 8.9% (previous history of congestive heart failure, ECG evidence of ischemia, and/or chronic obstructive lung disease); arrhythmia requiring treatment, 10.5% (preoperative ventricular premature beats and/or respiratory failure requiring ventilation for more than 48 hours); new arrhythmia, 8.4% (angina and/or chronic obstructive lung disease); respiratory failure, 8.4% (chronic obstructive lung disease, large volume of blood transfused, and/or occurrence of postoperative bleeding, cerebrovascular accident, congestive heart failure, or myocardial infarction); renal damage with rise in creatinine or blood urea nitrogen, 5.4% and/or renal failure requiring dialysis, 0.6% (elevated preoperative creatinine, suprarenal aortic cross-clamping, and/or renal vein ligation); diarrhea without evidence of ischemia colitis, 7.1% and ischemic colitis, 0.6% (pelvic flow interrupted); prolonged ileus, 11.0% (aortoiliac occlusive disease, deterioration of renal function, prolonged ventilation, and/or preoperative history of angina); superficial wound infection, 1.5% and deep infection, 0.5% (femoral anastomosis and/or female sex); coagulopathy, 1.1% (large volume of blood transfused).(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Multicenter prospective study of nonruptured abdominal aortic aneurysm. Part II. Variables predicting morbidity and mortality. 264 60


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