Electrical impedance of the liver during experimental long-term liver preservation

Measurements of electrical impedance were performed to assess ischemic damage in the rabbit liver during long-term preservation with University of Wisconsin (UW) or histidine-tryptophan-ketoglutarate (HTK) solution. The impedance was measured at a frequency of 200 Hz after in situ perfusion and after cold storage for 24 and 48 hours in UW or HTK solution (six livers per group). Z(200 Hz) was significantly higher (P < .01) after 48 compared with 24 hours of cold storage with both protection solutions without significant differences between the livers preserved with both solutions. Electrical impedance was observed to be a sensitive indicator of liver damage during long-term protection, showing similar preservation quality for both preservation solutions.     

Evaluation of cytoprotective drugs for liver preservation by pyridine nucleotide fluorometry

The cytoprotective effects of membrane-stabilizing drugs, such as chlorpromazine, allopurinol, dibucaine, phenoxybenzamine, and OP41483 (prostacyclin analogue), administered to perfusate and preservation medium were studied in rat liver, after 24 hours' preservation, by assessment of pyridine nucleotide fluorescence. On the fluorometric trace curve, amplitude (RxA) and velocity (RxV) from oxidation to reduction were determined. Percent decrease of RxA (%RxA) and that of RxV (%RxV) after 24 hours' preservation were calculated. At the end of preservation, the concentration of total adenine nucleotides of the liver, hepatic adenylate energy charge, and prepared mitochondrial oxidative phosphorylative activity were also measured. In the groups given phenoxybenzamine, dibucaine, and allopurinol, there was no significant difference among these parameters. In the chlorpromazine group, energy charge and %RxV were higher than in the drug-free group (p less than 0.05). In the OP41483 group, both energy charge and phosphorylation rate were significantly higher (p less than 0.05) and %RxV was significantly high (p less than 0.01) at concentrations of more than 3 nmol/L, compared with the values for those without drugs. These results suggest that the Redoximeter can provide accurate information on the effectiveness of cytoprotective drugs. It is also suggested that OP41483 has potential application for maintaining graft viability for human liver transplantation.     

The impact of extended preservation on clinical liver transplantation

The introduction of UW solution into clinical transplantation has permitted extended cold storage preservation of the liver. Over a 46-month period, we have performed 308 orthotopic liver transplants (266 primary, 42 retransplants) in 266 recipients. Our experience is divided into cold-storage preservation in Eurocollins (163 transplants in 140 recipients) and UW (145 transplants in 131 recipients) solutions. Donor and recipient factors were comparable between the two groups. The use of UW solution has permitted an increase in the mean preservation time from 5.2 +/- 1.0 [EC] to 12.8 +/- 4.3 [UW] hr (P less than 0.001). The mean total operating time was reduced but intraoperative blood loss was unchanged with UW preservation. The number of transplants performed during the daytime hours has increased dramatically (21.5% [EC] vs. 71% [UW], P less than 0.001). The incidence of primary nonfunction, hepatic artery thrombosis, 1-month graft survival, and early retransplantation were similar in the 2 groups. Initial allograft function as determined by bile production, histology, and clinical assessment were likewise similar. Mean serum bilirubin, transaminase, and prothrombin levels were virtually identical by 5 days posttransplant. The enhanced margin of safety afforded by extended preservation has increased the capability for distant organ procurement and sharing, minimized organ wastage, and improved the efficiency of organ retrieval. With the relaxation of logistical constraints, our rate of liver import has nearly doubled (20.9% [EC] vs. 39.3% [UW], P less than 0.001). Extended preservation has permitted the development of reduced-size liver grafting (n = 12), resulting in a significant reduction in the number of deaths occurring while awaiting transplantation. Therefore, we advocate the use of UW solution with selective extension of preservation based not only on donor and recipient factors but also on manpower, resource, and logistical considerations.     

Thermal and morphological effects of hepatic blood flow variations during liver resections with the Nd-YAG laser

Observations are presented on the thermal and anatomical effects of variations in hepatic blood flow during partial hepatic resection with the neodymium-doped yttrium aluminium garnet (Nd-YAG) laser in a comparative series of 21 pigs. Occlusion of the hepatic vessels both accelerates and prolongs the increase in parenchymal temperature, increases the thickness of surface necrosis and induces clotting in the underlying veins. On postoperative day 3, there is inflammatory cell and fibroblast migration which lasts until day 15. Between days 10 and 60, new vessel formation is apparent in the fibrous tissue underlying the resection site. The inflammatory reaction is less marked when hepatic blood flow is left intact. Clamping the hepatic vessels enhances tumour-cell death during surgery, promotes a local inflammatory response and may enhance the effects of local chemotherapy.

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Les effets thermiques et morphologiques des variations du flux sanguin pédiculaire sur les résections hépatiques partielles au laser YAG-Nd

Résumé Les auteurs présentent les effets thermiques et anatomiques dûs aux variations du flux sanguin hépatique lors des résections partielles du foie au laser YAG-Nd sur une série comparative de 21 porcs. Le clampage pédiculaire augmente l'amplitude et la durée de la réponse thermique, majore l'épaisseur de la nécrose de surface et induit un effet de blocage sur les veines avoisinant la résection. Il entraîne dès le troisième jour post-opératoire (J 3) un afflux de cellules inflammatoires et une fibrose qui s'élargit jusqu'à J15. De J 10 à 2 mois, une importante néovascularisation se développe sur la surface du foie réséqué. Le flux sanguin étant conservé, ces réactions sont retardées et moins intenses. Le clampage est donc proposé pour augmenter la destruction des cellules tumorales lors d'une résection, pour accroître les défenses locales ultérieures et pour faciliter l'action de la chimiothérapie.

     

奥曲肽对兔肝脏缺血-再灌注损伤的保护作用

目的 研究奥曲肽对兔肝脏缺血再灌注(I-R)损伤的保护作用.方法 24只新西兰大白兔随机均分为肝脏I-R组(R组)、奥曲肽预适应组(T组)和假手术组(C组).观察三组肝门阻断前(T1)、阻断后15 min(T2)、30 min(T3)、再灌注15 min(T4)、30 min(T5)、60 min(T6)、120 min(T7)、240 min(T8)的MAP和HR变化及T1、T3、T5、T6、T7、T8各时点丙氨酸氨基转移酶(ALT)、天冬氨酸氨基转移酶(AST)、乳酸脱氢酶(LDH)、内毒素(ET)以及肿瘤坏死因子α(TNF-α)、白细胞介素-1β(IL-1β)的变化.结果 R组T2～T6、T组T2～T4时MAP明显低于、HR明显慢于C组(P<0.05),R组在T2～T6时MAP明显低于、HR明显慢于T组(P<0.05);T3、T5～T8时,R、T两组ALT、AST、LDH、ET均明显高于C组(P<0.05);R组明显高于T组(P<0.05),R组T3、T5～T8、T组T5～T8日血浆TNF-α、IL-1β明显高于C组(P<0.05),且T组T3、T7、T8时血浆TNF-α明显低于R组,T5、T6时明显高于R组(P<0.05).T组T3、T5～T8时血浆IL-1β明显低于R组(P<0.05).结论 奥曲肽对兔肝脏1-R损伤有明显的保护作用,其机制可能与下调TNF-α、IL-1β等炎性介质和降低血浆中ET水平有关.     

Cold-inducible RNA binding protein agonist enhances the cardioprotective effect of UW solution during extended heart preservation

In heart transplantation, time restriction is an unavoidable thorny problem during cardiac transport. Cold storage is an important organ preservation method in donor heart transport. Cold-inducible RNA binding protein (CIRBP) has been proven to play a protective role under cold stress. In this study, we investigated the role of CIRBP in hypothermic cardioprotection during heart preservation in UW solution and explored a new approach to extend the heart preservation time. Cirbp-knockout (Cirbp^−/−), Cirbp-transgenic (Cirbp-Tg), and wild-type rats were, respectively, randomized into two groups based on various heart preservation times (6 or 12-hour group) (n = 8 per group). After preservation in UW solution, all hearts were mounted on a Langendorff apparatus and underwent measurement of cardiac parameters, histological analysis, and molecular study. Within the 6-hour preservation group, no significant difference was found in cardiac functions and histological changes between different rat species. However, after 12 hours of preservation, Cirbp^−/− rat hearts showed more apoptosis and worse cardiac function, but less apoptosis and better cardiac function were observed in Cirbp-Tg rat hearts. Furthermore, we found CIRBP-mediated cardiac ubiquinone (CoQ₁₀) biosynthesis plays an important role in extending heart preservation, and ubiquinone biosynthesis protein COQ9 was an essential down-stream regulator during this process. Finally, we found that zr17-2, a CIRBP agonist, could enhance the expression of CIRBP, which further enhances the synthesis of CoQ₁₀ and promotes scavenging of reactive oxygen species and ATP production to extend heart preservation. This study demonstrated that CIRBP-enhanced CoQ₁₀ biosynthesis during hypothermic heart preservation and zr17-2-supplemented UW solution could be a promising approach to ameliorate heart damage and extend heart preservation during cardiac transport.     

奥曲肽预处理对围术期肝脏缺血-再灌注损伤保护作用的临床研究

目的探讨奥曲肽预处理对围术期肝脏缺血-再灌注损伤保护作用及可能的机制。方法选择88例肝脏手术患者,随机分为研究组45例,对照组43例,术中行肝门阻断。研究组患者于手术前1h给予奥曲肽0.2mg皮下注射,对照组于手术前1h给予生理盐水1ml皮下注射。观察术前(T0)、术后6h(T1)、24h(T2)及7d(T3)时血清丙氨酸氨基转移酶(ALT)、天冬氨酸氨基转移酶(AST)、乳酸脱氢酶(LDH),肿瘤坏死因子α(TNF-α)及白细胞介素1β(IL-1β)的变化,手术部位切除后取标本行超氧化物歧化酶(SOD)、髓过氧化物酶(MPO)的检测。采用TUNEL法检测肝组织中的凋亡细胞数。结果 T0时两组之间ALT、AST、LDH及TNF-α、IL-1β差异无统计学意义。T1时两组ALT、AST、LDH及TNF-α、IL-1β明显高于T0时(P<0.05),对照组又明显高于研究组(P<0.05)。T2时两组ALT、AST、LDH开始下降,但仍然高于T0时(P<0.05),T3时恢复正常范围,而T2、T3时TNF-α、IL-1β降至正常范围。研究组肝组织MPO明显低于对照组(P<0.05),而SOD明显高于对照组(P<0.05)。肝组织中的凋亡细胞数对照组为(67.79±5.25)明显高于研究组(44.32±5.16)(P<0.01)。结论奥曲肽对围术期肝脏缺血-再灌注损伤有保护作用,其可能的机制为稳定细胞膜、抑制炎性反应及细胞凋亡。     

The effect of amrinone on liver regeneration in experimental hepatic resection model

BACKGROUND: The phosphodiesterase inhibitors (PDEIs) have been proposed to improve hepatic reperfusion injury and hepatosplanchnic circulation, but the effects of these agents on liver regeneration have not been investigated thoroughly. The aim of this study was to investigate the effect of amrinone, a PDEI, on liver regeneration in rats. MATERIALS AND METHODS: Sixty rats were divided into two groups, control and amrinone. Each group was then divided into three groups (n=10). An infusion of amrinone to the study group and of 0.9% NaCl to the control group was performed. Seventy percent liver resection was performed to the rats during the first hour of infusion. The infusion was maintained for 17 h after resection. A total of 18 h infusion was performed. Rats were allowed to survive for 24, 48, and 72 h, and then they were sacrificed. Biochemical, morphological, hematological, and histopathologic measurements and assessments were performed. RESULTS: There were statistically significant differences between the amrinone and control groups in alkaline phosphatase and relative liver weights at 24, 48, and 72 h (P<0.05). There also were statistically significant differences between the groups in AST, bilirubin, and albumine levels at 24 h, ALT and prothrombine time levels at 48 h, and aspartate aminotransferase and alanine aminotransferase levels at 72 h (P<0.05). Hepatic ATP levels, mitotic index, and proliferating cell nuclear antigen labeling index were significantly higher in amrinone group compared with control group at all three time intervals (P<0.05). CONCLUSIONS: Amrinone improves both morphological and functional liver regeneration after liver resection.     

Assessment of hepatic viability during cold ischemic preservation

A reliable and easy method for assessing the viability of a cold ischemia-preserved donor liver prior to transplanation into the recepient is needed. Based on an earlier study, we hypothesized that liver free fatty acid (FFA) leakage into the preservation fluid may be a useful, atraumatic indicator of irreversible ischemic injury. The aim of the present study was to determine the time course and magnitude of liver FFA release into the preservation solution and its correlation with the duration of cold ischemic preservation compatible with survival after transplantation. Rat livers (n=48) were flushed and preserved with University of Wisconsin (UW) solution at 4°C for 0, 12, 24, and 48 h. Thereafter, half of the livers were analyzed for preservation fluid FFA (gas-liquid chromatography) and protein. The other half were perfused with Krebs-Henseleit (KH) solution at 37°C for 1 h. Bile secretion and liver enzyme release (SGOT, SGPT, and LDH) were measured in addition to perfusate FFA and protein. Total FFA in the preservation fluid was 24 g/g wet tissue after 12 h; it increased sharply 2.6-fold after 24 h and 3.7-fold after 48 h of preservation. Bile production was normal after 12 h of preservation but fell by 20% and 54% after 24 h and 48 h, respectively. LDH release rose from a value of 20 U/l at 0 time to 120 U/l and 260 U/l after 24 h and 48 h of preservation. These results suggest that liver viability declines sharply between 12 and 24 h of cold ischemic preservation, which corresponds with a sharp decrease in the 1-week survival from 100% to 33% after 12 h and 24 h, respectively, of cold ischemic preservation. We conclude that measuring FFA and LDH in the preservation solution of donor livers may be a useful means of assessing the quality of the cold-preserved liver before insertion into the recipient. We also speculate that a threshold FFA level in the UW preservation fluid indicating irreversible damage may be in the order of 35 g total FFA/g liver. Studies on the clinical applicability of our findings are currently under way.     

Hemodynamics and coagulation in experimental auxiliary liver transplantation during fulminant hepatic failure.

In pigs, ischemic liver cell necrosis was induced by 6 hours' occlusion of the hepatic artery and the portal vein 3 days after construction of a side-to-side portacaval shunt and division of the hepatic ligaments. Two thirds of the liver of an MLC-compatible donor was heterotopically transplanted 13 hours (group I), and 3 hours (group II) after induction of liver failure. In group I (N = 11), three animals died of liver failure before or shortly after induction of anesthesia. Of the remaining pigs, two animals survived more than 2 weeks. In group II (N = 10), intraoperative hypotension was prevented by reduction of the interval between liver failure and transplantation and by thermodilution catheter monitored fluid replacement. A significant decrease in cardiac output and an increase of pulmonary and systemic vascular resistance were observed during auxiliary partial liver transplantation (APLT). In the immediate postoperative period, six pigs died of deficiencies in hemostasis that were caused by consumptive coagulopathy related to severe host liver damage rather than fibrinolysis. Two pigs in group II survived in good condition 12 and 42 days after APLT. In the longer surviving pigs of both groups, either the graft or the host liver recovered. Processes that might be responsible for the observed hemodynamic changes and coagulation disorders are discussed. These results indicate that APLT is technically feasible in severely ill pigs with acute hepatic failure.     

Local liberation of cytokines during liver preservation

In order to investigate locally produced mediators during the process of organ storage in liver transplantation, we collected the liver preservation solution effluent of 15 transplanted livers and compared it with serum samples taken preoperatively from donor and recipient, as well as 60 min after reperfusion. The mean ischemia time ± SEM was 10 h 10 min ± 53 min. Mean concentrations in University of Wisconsin preservation solution effluent were: interleukin-(IL-)1β 154 ± 77 pg/ml; IL-1 receptor antagonist (IL-1 ra) 1281 ± 309 pg/ml; IL-6 412 ± 90 pg/ml; and for tumor necrosis factor-(TNF-)α 74 ± 21 pg/ml. Cytokine levels in the donors were lower than those detected in the effluent. All measured cytokines showed higher concentrations in the effluent compared to those of the recipient prior to the operation. With respect to a comparison of donor and recipient values, no correlation is evident. Likewise, the ischemic time does not correlate with effluent values. Further development of liver preservation concepts requires information about the state of the graft before reperfusion. Data on cytokine liberation may serve as a helpful tool for the further development of preservation concepts because they enable an estimation of cell activation during preservation. Received: 2 June 1997 Accepted: 10 November 1998     

Protective effect of fructose-1,6-bisphosphate in the cold storage solution for liver preservation in rat hepatic transplantation

Fructose-1,6-bisphosphate (FBP) has been reported to have a protective effect on liver injury following ischemic/reperfusion periods. FBP maintains ATP levels and thereby cellular energy metabolism, which is important to the liver during cold preservation. In the present study, we evaluated the effects of FBP on the composition of storage solutions for cold liver preservation. Adult male Wistar rats were randomly divided into three experimental groups. Hepatic perfusion and preservation were performed with UW, UW plus 10 mmol/L FBP (UWM), and FBP 10 mmol/L (FBPS) alone solutions. Biochemical measurements of AST, ALT, and TBARS were performed on samples of the cold storage solution at 0, 12, 18, and 24 hours preservation. FBPS and UW solutions showed similar preservation grades during 18 hours. Addition of 10 mmol/L of FBP to UW solution induced liver injury and a poor preservation grade. FBP appears to protect the liver from injury caused by free radicals when the preservation time is less than 18 hours. Therefore, FBP may exert a protective effect for the preservation of livers during cold storage, and could represent an important component of new cold storage solutions.     

Protection of the liver during hepatic surgery

Very few areas in medicine have seen as many controversies as the evaluation and treatment of patients with liver diseases. Many novel therapies, often marketed before conclusive demonstration of their efficacy, have been developed to enable selective destruction of liver tumors to minimize the risk of liver failure associated with major surgery. Whether these techniques are effective and result in lesser complications often remains speculative. Persisting challenges in selecting the optimal therapy are the evaluation of the risk of surgery in patients with normal or diseased liver and the preparation for surgery. A panel of hepato-biliary surgeons experienced in the management of complex cases convened at the annual meeting of the American Hepato-Pancreato-Biliary Association in Boston, MA, to address the rapidly evolving field of protective strategies for hepatic surgery.     

冷保存大鼠部分肝移植模型的建立

目的　建立稳定的大鼠部分肝移植模型 ,研究冷保存对部分肝移植后肝再生的影响。方法　采用雄性SD大鼠 ,双袖套法行部分肝移植 ,观察不同冷保存时间受体生存状况以及各组手术情况。结果　各组移植肝平均体积为 62 % -64 % ,无肝期为 14 -15min。长时间冷保存后大鼠 7d存活率明显下降 ,生存分析显示各组间差异有显著性。 8h冷保存后大鼠 7d存活率为 40 % ,与临床辟裂式肝移植 1年生存率相似。结论　 8h保存大鼠部分肝移植模型是研究冷保存对部分肝移植肝再生影响的较好模型