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 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The normal microvascular permeability of the ascending colon in horses and the microvascular permeability of that segment after ischemia and reperfusion were investigated. Microvascular permeability was estimated by the ratio of lymphatic protein to plasma protein concentration (Cl/Cp) at high lymph flow rates in 8 adult horses in 2 equal groups: normal and ischemic (2-hour period). Lymphatic flow rates and lymph and plasma protein concentrations were determined. Intestinal biopsy specimens were obtained at the end of each experiment. Flow independent values were selected and compared by one-way ANOVA, and the mean and SEM of these values were determined. The mean Cl/Cp ratios for the flow independent part of each data set were as follows: normal = 0.36 +/- 0.08; ischemic = 0.70 +/- 0.08. These groups were significantly different (P < or = 0.0001). Microscopic evaluation revealed mild congestion and edema in the normal group. The ischemic group had mild to moderate mucosal degeneration, with moderate to severe congestion and edema. We concluded that ischemia of the ascending colon, when followed by reperfusion, results in a significant increase in microvascular permeability.
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PMID:Microvascular permeability changes in ischemia/reperfusion injury in the ascending colon of horses. 142 57

We hypothesized that either through local myocardial or systemic effects, adenosine could be used to control hypotension during ischemia. Therefore, we compared the effects of systemic with intracoronary infusion of adenosine on myocardial hemodynamics and metabolism during ischemia in 27 dogs. Left anterior descending artery (LADa) flow was measured and the LADa constricted by a micrometer to restrict resting flow by 50%, 75%, and 100%. Adenosine was infused either systemically (n = 9), to maintain mean aortic pressure at 50-60 mm Hg, or directly into the LADa (n = 9), to create maximal coronary hyperperfusion; no adenosine was infused in the control group (n = 9). With systemic adenosine, during each constriction aortic pressure, left ventricular first derivative (LV dP/dt), and heart rate (HR) decreased: aortic pressure by 56.1% +/- 2.9% (mean +/- SEM), LV dP/dt by 36.2% +/- 2.2%, systemic resistance by 42.7% +/- 5%, and HR by 38.7% +/- 3% during 50% constriction (P less than 0.05 for each variable). Intracoronary adenosine decreased only aortic pressure, LV dP/dt, and HR, all to a lesser extent: aortic pressure by 5% +/- 2.8%, LV dP/dt by 15% +/- 1.2%, and HR by 4.6% +/- 1.7% (P less than 0.05, compared with systemic adenosine for each variable). With systemic adenosine only in the nonischemic area, regional myocardial blood flow increased and remained high, from 224.6 +/- 65.2 to 342 +/- 46.2 mL.min-1.100 g-1 during 50% constriction (P less than 0.05); with intracoronary adenosine, ischemic zone regional myocardial blood flow increased, but not consistently. In the ischemic area, O2 consumption was less with than without systemic adenosine; also, lactate flux production was less positive (-60.2 +/- 37.6 compared with 80.3 +/- 20.2 mmol.min-1.100 g-1 x 10(-3) during 50% constriction; P less than 0.05). Systemic infusion of adenosine during coronary hypoperfusion improves regional metabolism during ischemia and, thus, may mitigate myocardial ischemia. The mechanism by which systemic infusion improves metabolic status may be by decreases in both systemic pressure and systemic vascular resistance.
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PMID:Adenosine for controlled hypotension: systemic compared with intracoronary infusion in dogs. 151 Feb 51

In 12 open-chest dogs, cardiac sympathetic nervous activity (CSNA) was recorded before and after occlusion of the left anterior descending coronary artery as well as during reperfusion and ventricular fibrillation (VF). In 7 control animals, CSNA did not significantly differ from preocclusion levels when determined 20 min after occlusion (+3.5 +/- 1.5%, mean +/- SEM) and up to 15 min following reperfusion (+1.5 +/- 0.6%). However, VF was associated with a potential increase in CSNA by 106 +/- 15.5% (p less than 0.001). The effect of lidocaine (6 mg/kg) on cardiac sympathetic tone was examined in 5 additional animals. Lidocaine reduced control CSNA by 23 +/- 4.7% (p less than 0.001); subsequent ischemia and reperfusion did not substantially change the level of preocclusion activity. CSNA decreased significantly also during VF (52 +/- 4.2%, p less than 0.001). In conclusion, efferent CSNA was slightly altered in the course of acute myocardial ischemia and reperfusion, but significantly increased during VF. Lidocaine produced marked attenuation of CSNA in anesthetized dogs.
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PMID:Cardiac sympathetic nervous activity during myocardial ischemia, reperfusion and ventricular fibrillation in the dog--effects of intravenous lidocaine. 151 66

To determine the organ distribution of production of the three endothelin (ET) isopeptides, we have developed three ribonuclease protection assays specific for the messenger RNAs (mRNAs) of rat ETs 1, 2, and 3.12 organs from adult Sprague-Dawley rats were examined: heart, lung, liver, spleen, kidney, stomach, small intestine, large intestine, testis, muscle, salivary gland, and brain. The mRNA for ET1 was five times more abundant in the lung than in any other organ studied, moderate expression was seen in the large intestine, and lower levels of mRNA were detected in each of the other organs examined. ET2 was expressed at high level in both large and small intestine and at low level in stomach, muscle, and heart, but ET2 mRNA could not be detected elsewhere. ET3 mRNA was found in all organs, particularly in small intestine, lung, kidney, and large intestine. Because of reports suggesting that ETs might be involved in the hypoperfusion and hypofiltration observed in postischemic kidneys, we have also studied levels of mRNA in kidneys that had previously been subjected to 25 or 45 min of clamping of the renal pedicle. At 6 h after 45 min of ischemia, ET1 mRNA increased to a peak of 421 +/- 69% (mean +/- SEM, n = 3) of that in a standard renal RNA preparation. By contrast, ET3 mRNA decreased in the postischemic organ, falling to a value of 19 +/- 2% of standard at the same time point. The effects of ischemia on ET1 and ET3 mRNAs were long-lasting, with elevation of ET1 and depression of ET3 persisting for days. ET2 mRNA remained undetectable throughout. These findings (a) support a role for ET1 in postischemic renal vascular phenomena and (b) demonstrate a situation in which the expression of ET isoforms is clearly subject to differential regulation.
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PMID:Organ distribution of the three rat endothelin messenger RNAs and the effects of ischemia on renal gene expression. 152 10

Measurement of surface tissue pO2 (ptO2) with surface electrodes is increasingly applied in experimental medicine. Its use on the beating heart may seem to be problematic because transmural gradients of tissue pO2 would reduce the validity of pO2 determinations in the epicardial layers. This study attempted to determine whether ptO2 may be a valid and sensitive indicator of transmural myocardial oxygenation. In order to measure ptO2, two eight-channel Clark-type electrodes were placed on a beating porcine left ventricle (n = 13). Measurements were made at different degrees of acute stenosis of the left anterior descending artery (LAD). A 24-F cannula was inserted into the great cardiac vein, draining the poststenotic myocardium to obtain coronary venous blood samples. Transmural metabolic changes were detected simultaneously by coronary venous blood gas parameters and lactate levels. Epicardial tissue pO2 was 49 +/- 2 mm Hg (mean +/- SEM) before stenosis and decreased to a mean value of 25 +/- 2 mm Hg during stenosis. Different degrees of LAD stenosis (ptO2 range: 12-35 mm Hg) were substantial enough to alter arterio-coronary venous lactate difference (avd lactate) from +0.31 +/- 0.07 mmol/l (control) to -0.62 +/- 0.15 mmol/l (stenosis). A significant linear correlation between changes of ptO2 (delta ptO2) and changes of avd lactate (delta avd lactate) resulted (y = 0.59 + 0.62x; r = 0.86; p less than or equal to 0.001). However, linear regression analysis between delta ptO2 correlated with the corresponding data from coronary venous pO2 (delta pO2cv) oxygen content (delta O2contcv), and oxygen saturation (delta O2satcv) showed no significant correlations. We conclude that measurement of ptO2 is a sensitive and valuable indicator of transmural oxygenation in ischemic myocardium, whereas pO2cv, O2contcv and O2satcv do not seem to be valid predictors of ischemia in myocardial oxygenation.
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PMID:Myocardial oxygenation and transmural lactate metabolism during experimental acute coronary stenosis in pigs. 156 51

Tumor necrosis factor (TNF)-alpha has significant biologic actions in many circumstances, such as infectious diseases, ischemia/reperfusion injury, and delayed-type hypersensitivity reactions. Based on the hypothesis that manipulation of TNF can play an important role in treatment of heart transplant rejection, the objective of this study was to determine whether anti-TNF antibodies could prolong cardiac allograft survival. Hearts from brown rats were transplanted to the necks of recipient Lewis rats. Graft survival was determined by direct palpation of the heart; complete graft rejection was defined by cessation of contraction. In untreated rats, the hearts were rejected 6.8 +/- 0.6 days (n = 10; mean +/- SEM) after transplantation. The mononuclear cell infiltrate in the transplanted hearts stained intensely for TNF by immunohistochemistry, indicating that TNF was present within the inflammatory cells associated with the rejection process. In rats receiving a single injection of anti-TNF antibody at the time of transplantation (n = 6), however, graft survival was nearly doubled (12.7 +/- 1.4 days; p less than 0.001 vs controls). Prolonged cardiac graft survival was also evident if the anti-TNF treatment was delayed until 1 day (n = 5; rejection at 16.2 +/- 2.4 days; p less than 0.001 vs controls) or even 3 days after transplantation (n = 5; rejection at 11.4 +/- 2.3 days; p less than 0.005 vs controls). Treatment at 5 days after transplantation, however, was not effective (n = 3; rejection at 7.7 +/- 0.6 days; p, not significant vs controls). The data indicate that a single bolus of anti-TNF antibodies can delay heart transplant rejection, even when administered up to 3 days after implantation, supporting the potential utility of anti-TNF therapy for treatment of heart transplant rejection.
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PMID:Antibodies against tumor necrosis factor prolong cardiac allograft survival in the rat. 157 39

The present study examines whether leukocyte depletion can prevent postreperfusion ultrastructural injury in transplanted human hearts. Thirty-two patients undergoing orthotopic cardiac transplantation were randomized to receive either enriched, warm, whole blood (Group I; n = 16) or enriched, warm, leukocyte-depleted blood (Group II; n = 16) reperfusion. Donor hearts were arrested with 1 liter of 4 degrees C crystalloid cardioplegia and topically cooled. RV endomyocardial biopsies taken at end-ischemia and following reperfusion were assessed in a blinded fashion and graded according to injury (1 = minimal to 4 = severe). The mean ischemic time (Group I = 142 min, Group II = 153 min) was similar in the two groups. End-ischemic biopsies showed mild-moderate interstitial edema and mild capillary endothelial swelling in both groups with similar injury scores (Group 1 = 1.3 +/- 0.09 (means +/- SEM), Group 2 = 1.25 +/- 0.08). Postreperfusion biopsies in Group I showed nuclear chromatin clumping, moderate mitochondrial swelling, marked capillary endothelial swelling, and marked interstitial edema with a grade of 2.6 +/- 0.14 (P less than 0.001, paired t test). In contrast, postreperfusion biopsies in Group II showed minimal changes with a grade of 1.33 +/- 0.09, P less than 0.0001 in comparison to Group I Leukocyte-depleted reperfusion of human transplanted hearts prevents ultrastructural injury. This may allow safe extension of the ischemic period and result in improved graft function.
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PMID:Leukocyte-depleted reperfusion of transplanted human hearts prevents ultrastructural evidence of reperfusion injury. 159 67

The purpose of this study was to evaluate the significance of increased Tl-201 uptake by the lungs after oral dipyridamole testing. In conjunction with myocardial perfusion scintigraphy, intravenous dipyridamole has been recently approved as an alternative to exercise for the evaluation of coronary artery disease in patients who cannot adequately exercise, and it will largely replace oral dipyridamole testing. This study contributes to the understanding of the significance of increased lung thallium uptake during pharmacologic stress testing. Oral dipyridamole, 400 mg, was administered to 192 patients undergoing Tl-201 imaging for clinical indications. Mild adverse effects occurred in 31% of patients (chest pain, nausea, headache, or flushing). Dipyridamole had minimal hemodynamic effects. The lung/heart thallium activity ratio was determined in 152 patients. These were subdivided into four groups according to the presence or absence of ischemia, transient myocardial perfusion defect, or scar as indicated by a fixed myocardial perfusion defect. In 61 patients without transient myocardial perfusion defect or fixed myocardial perfusion defect (group 1), the lung/heart thallium activity ratio was 0.39 +/- 0.01 (mean +/- SEM). In 31 patients without transient myocardial perfusion defect but with fixed myocardial perfusion defect (group 2), the lung/heart thallium activity ratio was higher, 0.44 +/- 0.02 (P less than 0.05). In 27 patients with transient myocardial perfusion defect but no fixed myocardial perfusion defect (group 3) and in 33 patients with both transient myocardial perfusion defect and fixed myocardial perfusion defect (group 4), the lung/heart thallium activity ratio was 0.51 +/- 0.03 and 0.52 +/- 0.03, respectively, both significantly higher than either group 1 or group 2 (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Significance of increased Tl-201 uptake by the lungs in patients undergoing oral dipyridamole-thallium myocardial imaging. 161 45

In attempting to determine whether or not multiple injections of human chorionic gonadotropin (hCG) augment testis blood flow, adult male rats were injected with three doses of 10 IU of hCG every other day and testis blood flow was determined on day 5, the day of the final injection. Testis blood flow (mL/100 g testis tissue/min +/- SEM) as measured by the 133Xe washout method increased from 10.8 +/- 1.3 to 20.4 +/- 4.5 (p less than 0.05) after the three doses of hCG. These observations suggest that multiple injections of hCG appear to have the same effect as a single dose of hCG in increasing testis blood flow. This supports the hypothesis that hCG should be administered to all patients undergoing orchiopexy in the hope that the increased perfusion of the gonad will make it less susceptible to ischemia during the surgical procedure.
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PMID:Effects of multiple injections of HCG on testis blood flow. 162 19

During lung transplantation, a number of factors may cause endothelial injury to the donor organ, including ischemia, inadequate preservation, cardiopulmonary bypass, high potassium concentrations, and reperfusion. In this study, protein accumulation index (PAI) was used to assess pulmonary endothelial permeability (PEP) in ten patients immediately after lung transplantation. Six were studied sequentially every other day for ten days postoperatively. The PAI was also measured using the same technique in a group of 11 normal volunteers. Mean PAI x 10(-3)/min +/- (SEM) for ten patients measured within 36 h of transplantation was 1.27 (0.56) compared with 0.45 (0.08) for the normal group (p = 0.09). No correlation was found between preservation time and PAI following reperfusion. Three episodes of lung rejection were observed in two patients during the first ten postoperative days, during which PAI rose to 2.26 (0.26) compared with 0.73 (0.11) for all other studies in the group (p less than 0.01). We conclude that no increase in PEP could be demonstrated after graft reperfusion following lung transplantation as assessed by PAI in this small group of patients. However, further studies may show the technique to be useful in the detection of subsequent episodes of graft rejection.
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PMID:Pulmonary endothelial permeability following lung transplantation. 164 25


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