ISSN:0041-1337    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Background.Both livers and hepatocytes from pigs have been proposed for the treatment of end-stage liver diseases, as an alternative to allogeneic liver transplants. However, little is known of the capability of porcine hepatocytes to fulfill the biotransformation pathways of toxic compounds, including those released from livers in acute failure. We have studied the activity and expression of detoxifying enzymes in porcine livers and in cultured hepatocytes and their induction by phenobarbital.Methods.Cytochromes P450 (CYP) 1A, 2B, and 3A and GST-like activities were tested with the following specific substrates: 7-ethoxyresorufin, 7-pentoxyresorufin, nifedipine, testosterone, 1-chloro-2,4-dinitrobenzene, 1,2-dichloro-4-nitrobenzene, and ethacrinic acid. CYP 1A1/2-, 2B1/2-, 2E1- and 3A4-related and GSTα proteins were analyzed by Western blotting and CYP 1A1/2, 2B1/2, 2C6, 2E1, and 3A4, aldehyde dehydrogenase, epoxide hydrolase, and GSTα-like RNA by Northern blotting.Results.Enzymatic activities reflecting the expression of CYP 1A-, CYP 2B-, CYP 2E1-, and CYP 3A-like genes, that is, ethoxyresorufin-O-deethylase, pentoxyresorufin-O-deethylase, nifedipine oxidase and testosterone 6β-hydroxylase, and chlorzoxazone 6-hydroxylase, were identified in pig livers. CYP 1A and CYP 2E1, GSTα-like proteins, CYP 1A, 2C, and 2E, epoxide hydrolase, aldehyde dehydrogenase, and GST like RNA were expressed in vivo and in vitro. CYP 2B and CYP 3A RNA and proteins, and their associated activities were induced by phenobarbital.Conclusions.Porcine hepatocytes express the most important biotransformation enzymes and their corresponding activities and RNA. Thus, livers and hepatocytes from pigs can detoxify a large spectrum of exogenous and endogenous compounds, which makes them a convenient substitute for allogeneic transplants for patients with liver failure.

ISSN:0041-1337    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Background.Polarized arrest, induced by tetrodotoxin (TTX) at an optimal concentration of 22 μmol/L, has been shown to reduce ionic imbalance and improve myocardial preservation compared with hyperkalemic (depolarized) arrest. Additional pharmacologic manipulation of ionic changes (involving inhibition of Na+influx by the Na+/H+exchanger [HOE694] and Na+/K+/2Cl−cotransporter [furosemide], and calcium desensitization [BDM] may further improve long-term preservation. In this study, we (i) established optimal concentrations of each drug, (ii) determined additive effects of optimal concentrations of each drug and (iii) compared our optimal preservation solution to an established depolarizing cardioplegia (St Thomas' Hospital solution No 2: STH2) used during long-term hypothermic storage for clinical transplantation.Methods.The isolated working rat heart, perfused with Krebs Henseleit (KH) buffer was used; cardiac function was measured after 20 min aerobic working mode perfusion. The hearts (n=6/group) were arrested with a 2 ml infusion (for 30 sec) of the polarizing (control) solution (22 μmol/L TTX in KH) or control+drug and subjected to 5 hr or 8 hr of storage at 7.5°C in the arresting solution. Postischemic function during reperfusion was measured (expressed as percentage of preischemic function).Results.Dose-response studies established optimal concentrations of HOE694 (10 μmol/L), furosemide (1.0 μmol/L) and BDM (30 mmol/L) in the polarizing (control) solution. Sequential addition to the control solution (Group I) of optimal concentrations of HOE694 (Group II), furosemide (Group III), and BDM (Group IV) were compared with STH2 (Group V); postischemic recovery of aortic flow was 29±7%, 49±6%*, 56±2%*, 76±3%*, and 25±6%, respectively (*P<0.05 vs. I and V). Creatine kinase leakage was lowest, and myocardial ATP content was highest in Group IV.Conclusions.A polarizing preservation solution (KH+TTX) containing HOE694, furosemide, and BDM significantly enhanced long-term preservation compared with an optimized depolarizing solution (STH2) used clinically for long-term donor heart preservation.

ISSN:0041-1337    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Background.Neuroelectrophysiological abnormalities in diabetes indicate nervous function failure. Restoration of euglycemia by islet transplantation may prevent or reverse these abnormalities.Methods.Pancreatic islets were transplanted in inbred Lewis rats after 15 days (Ta12, primary prevention) or 8 months (Tb12, secondary prevention) from streptozotocin-induced diabetes. Transplanted and control (normal and diabetic) rats were followed for a total period of 12 months. Metabolic parameters, somato-sensory, brain-stem auditory, and visual evoked potentials were determined at the beginning and at the end of the study and before transplantation for secondary prevention.Results.The metabolic parameters in transplanted animals were similar to those of normal animals. Ta12 and normal group somato-sensory conduction velocities did not vary and were always significantly higher than those of diabetic animals. By contrast, Tb12 group conduction velocities showed only a partial improvement, values lying between those of diabetic and normal rats. Brain-stem auditory (waves I, II, and III) latencies in Ta12 group were similar to those of normal rats and significantly lower than those of diabetic animals (wave I:P<0.01; waves II and III:P<0.05). Tb12 group wave I and II latency values remained altered (P<0.005 andP<0.01 versus normal values respectively). Visual evoked potentials-P1 wave latencies in transplanted rats were always higher than those of normal and diabetic animals.Conclusions.After primary prevention, central and peripheral neurological alterations were abolished. After secondary prevention, transplantation beneficial effects were partial, occurring mainly at peripheral level. These results highlight the importance of early transplantation to prevent hyperglycemia-dependent neuroelectrophysiological alterations.

ISSN:0041-1337    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Background.The monocyte chemoattractant protein-1 (MCP-1) is produced during reperfusion injury and induces tissue factor that is the initiator of the clotting cascade. Neutrophil elastase is a crutial mediator of inflammatory tissue damage. Activation of the coagulation system stimulates cytokine production by activated leukocytes. We investigated the effects of neutrophil elastase and oxygen radicals generated by hypoxia associated with microthrombus formation on MCP-1 expression after ischemia/reperfusion in rat liver.Methods.In vitro MCP-1 production by macrophages after stimulation with human neutrophil elastase (HNE) or oxygen radicals generated by hypoxanthine and xanthine oxidase was examined. Liver ischemia was induced in rats by occluding the portal vein for 30 min. An inhibitor of human neutrophil elastase (ONO-5046·Na, 10 mg/kg) and antithrombin III (AT-III, 250 U/kg) were injected i.v. 5 min before vascular clamping. Serum concentrations of MCP-1 were measured by enzyme-linked immunosorbent assay.Results.Human neutrophil elastase or oxygen radicals significantly enhanced in vitro MCP-1 production by macrophages. Serum MCP-1 concentrations reached a peak at 6 hr after reperfusion and then gradually decreased. However, pretreatment of animals with AT-III or ONO-5046·Na alone resulted in significantly smaller increases in serum concentrations of MCP-1 after reperfusion. Pretreatment with both ONO-5046·Na and AT-III produced additive effects. The combined treatment with ONO-5046·Na and AT-III significantly reduced MCP-1 mRNA in liver after ischemia/reperfusion.Conclusions.MCP-1 production by macrophages is stimulated by neutrophil elastase and oxygen radicals generated by hypoxia, probably due to microthrombus formation after ischemia/reperfusion of the rat liver.

ISSN:0041-1337    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Background.Historically, ex vivo physiological evaluation of cadaveric renal allografts has been limited to assessing perfusate flow (PF) during hypothermic perfusion preservation (HPP). Using a small animal model, we have previously described a method for continuous monitoring of glomerular filtration rate (GFR) during HPP. Our study was undertaken to determine if monitoring GFR and PF during HPP distinguished kidneys subjected to preretrieval warm ischemic (WI) injury more reliably than PF alone.Methods.In situ WI was induced in Lewis rats (n=10) by extrinsic occlusion of the suprarenal aorta for 30 min. After in situ cold perfusion and retrieval, the left kidney underwent 16 hr of HPP. Nonischemic (NI) control kidneys (n=10) were retrieved in the absence of suprarenal aortic occlusion. Longitudinal changes in PF, GFR, and filtration fraction (FF) during HPP were compared in WI versus NI kidneys (FF=GFR/PF × 100%).Results.PF remained the same in both cohorts throughout HPP. GFR, however, increased to a significantly greater degree in WI versus NI kidneys during the first 4 hr of HPP (713±401 vs. 26±23%, respectively) (P<0.05). The increase in FF at 4 hr was 1203±696% in the WI kidneys versus 83±46% in the NI controls (P<0.05).Conclusions.In contrast to PF alone, measurement of both PF and GFR distinguished kidneys subjected to pre-WI from NI controls. The data provide a means to determine if monitoring of both GFR and PF during HPP will predict short- and long-term renal allograft function more reliably than PF alone.

ISSN:0041-1337    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Background.We determined whether the coupling between cerebral blood flow (CBF) and oxygen metabolism (CMRO2) is preserved during liver transplantation. Because of cerebrovascular dilatation, we hypothesized that cerebral metabolic autoregulation is impaired, because CBF becomes uncoupled from CMRO2during the reperfusion phase of the operation.Materials and Methods.In a prospective study, 13 patients (8 women, median age 46, range 21-56) with liver failure (10 with end-stage chronic liver disease and 3 with acute liver failure) were enrolled. Catheters were placed in a femoral artery and in the internal jugular vein for calculation of the cerebral arteriovenous oxygen content difference (AVDO2). CBF was recorded by the133Xenon injection technique, and by transcranial Doppler sonography determined mean flow velocity (Vmean) in the middle cerebral artery. The CMRO2was calculated as the AVDO2times CBF and the cerebrovascular resistance (CVR) as the mean arterial pressure to CBF ratio. An index of large cerebral artery diameter was expressed by the CBF to Vmeanratio.Results.From induction of anesthesia to the anhepatic period, CBF decreased from a median of 47 (interquartiles 31-55) to 41 (37-48) ml 100 g−1min−1, whereas the CMRO2remained unchanged (1.3 [0.9-2.5] vs. 1.7 [0.9-2.3] ml 100 g−1min−1). In the reperfusion phase, the CBF increased to 51 (45-54) ml 100 g−1min−1, whereas the CMRO2remained unchanged at 1.1 (1.0-2.5) ml 100 g−1min−1. The CVR decreased from 2.0 mm Hg (1.4-2.1) to 1.4 (1.1-1.8) mm Hg−1min 100 g ml. In the anhepatic phase, mean arterial pressure decreased from 92 mm Hg (84-98) to 85 (80-92) mm Hg and at reperfusion it was 80 (71-105) mm Hg. From the anhepatic to the reperfusion phase, the CBF increased 7% (0 to 26) for each mm Hg concomitant increase in PaCO2. The CBF to Vmeanratio remained stable (1.0 [0.8-1.2] vs. 0.9 [0.7-1.1] ml 100 g−1min−1cm−1sec).Conclusion.During the reperfusion phase of liver transplantations, cerebrovascular dilatation uncouples cerebral oxidative metabolism from blood flow. The increase in CBF is beyond what can be explained by changes in arterial carbon dioxide tension and arterial pressure.

ISSN:0041-1337    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Background.Determination of coronary flow reserve (CFR) is increasingly used to assess the functional significance of cardiac allograft vasculopathy. Although the relation between CFR and angiographically defined vasculopathy has been studied extensively, little is known about other factors determining CFR in heart transplant recipients without significant lesions by coronary angiography.Methods.Sixty consecutive patients were studied 0.5 to 148 months after heart transplantation with intracoronary Doppler and intravascular ultrasound. An endothelium-independent CFR≤2.5 was defined as abnormal. Stepwise logistic regression analysis was used to identify factors (demographic data of donor and recipient, lipid profile, epicardial vessel morphology by intravascular ultrasound, left ventricular hypertrophy, acute rejection episodes, and hemodynamics) potentially associated with a reduced CFR.Results.Only the presence of left ventricular hypertrophy (48% vs. 14%,P=0.007 andP=0.023, bivariate and multivariate analysis, respectively) and higher donor ages (41±12 vs. 29±11 years,P=0.002 andP=0.013, bivariate and multivariate analysis, respectively) showed an independent association with an abnormal flow reserve. CFR in patients with left ventricular hypertrophy was reduced due to higher baseline flow velocities (27±11 vs. 20±6 cm/sec,P=0.004). Furthermore, resting flow velocity increased as a function of donor age (r=0.264,P=0.047), while hyperemic flow velocity was not different. Other patient characteristics and hemodynamics did not affect CFR.Conclusion.The presence of left ventricular hypertrophy and higher donor ages independently contribute to a reduced CFR in patients after heart transplantation. This reduction in CFR is due to elevated baseline flow velocities rather than to a change in hyperemic flow velocities. These findings should be taken into account for the interpretation of reduced CFR values obtained by intracoronary Doppler in heart transplant recipients without angiographically overt coronary lesions.

ISSN:0041-1337    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Background.Little is known concerning gastric motility after renal transplantation and on the impact of immunosuppressants on gastric emptying.Methods.Gastric emptying was measured in renal transplant recipients, taking different immunosuppressive therapy (steroids and cyclosporine/azathioprine/FK-506), and compared with normal volunteers.Results.After renal transplantation, gastric emptying of liquids was normal, irrespective of the type of immunosuppression. However, solid gastric emptying was significantly faster in FK-506-treated patients compared with patients taking cyclosporine for all measured emptying parameters. Compared with normal volunteers solid gastric emptying was slower in patients taking cyclosporine, comparable in azathioprine treated patients, and characterized by an unusual short lag phase in patients taking FK-506.Conclusions.In stable renal transplant recipients gastric emptying of solids was significantly faster in patients on FK-506 compared with patients taking cyclosporine. Therefore, FK-506 may be the immunosuppressant of choice after solid organ transplantation in patients with problems related to gastroparesis.

ISSN:0041-1337    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Background.Severe liver disease, including fulminant hepatic failure and venoocclusive disease can occur after bone marrow transplantation (BMT). The aim of our study was to assess risk factors for veno occlusive disease and severe liver disease occurring within 6 months from BMT.Methods.A total of 193 consecutive patients from 15 BMT Centers were prospectively enrolled between January and June 1995. Data on donors and recipients before and after transplant were collected and included age, gender, alanine aminotransferase (ALT), hepatitis B (HBV), and hepatitis C virus (HCV) markers, hematological disease, status and type of BMT, conditioning regimen and graft versus host disease prophylaxis. Statistical analysis included univariate descriptive and multivariate analysis based on logistic regression on major end-points.Results.Forty-three of 193 patients died during the study period, and liver disease was the main cause of death (13 of 43, 30%). Incidence of severe veno occlusive disease was 8%, fulminant hepatic failure 0.5% and 12% of cases had ALT >500 U/L (normal ≤42 U/L). A de novo HBV or HCV infection occurred in 3.2 and 7% of patients respectively. Predictive risk factors for life-threatening liver disease were: unrelated donors (relative risk=5.8, confidence interval=1.7-19.8) and abnormal BMT donor ALT (relative risk=6.3, confidence interval=1.5-25.5).Conclusions.This study indicates that ongoing or previous infection with HBV or HCV in donor or recipient is not an absolute contraindication for BMT. However, abnormal ALT levels in BMT donors were a significant predictor of potentially lethal liver complications. The occurrence of de novo HBV or HCV infection did not correlate with severity of liver disease observed in the first 6 months posttransplant. These findings should be carefully evaluated before disregarding HBV or HCV positive siblings with normal transaminase levels in favor of unrelated donors.

ISSN:0041-1337    

出版商:OVID    

年代:1999

数据来源: OVID