Metabolic function of grafted liver in rats

We studied the metabolic variations in grafted livers at different times after transplant by measuring the hepatic energy and redox states. Five groups of rats were studied: control ungrafted Wistar (RT1y) rats (group 1), ungrafted Wistar rats with ligature of the hepatic artery (group 2), isografted Wistar rats (group 3), allografted Wistar rats with livers from ACI (RT1a) donors (group 4, long-term surviving rat strain combination), and allografted Wistar rats with livers from BN (RT1n) rats (group 5, rejector rats). The metabolism of grafted livers was studied for 7 days in groups 2 and 3, for 2 months in group 4, and at the time of rejection in group 5. Adenine nucleotide levels (ATP, ADP, AMP) were significantly impaired at 24 hr and at 48 hr from grafting in isografted and in allografted livers, and the reestablishment of normal values began at the 7th day from grafting. Cytoplasmic NAD+/NADH ratios were lowered at 24 hr from grafting in isografted and in allografted livers. Mitochondrial NAD+/NADH ratios were lowered at 24 hr in isografted livers and at 24 hr and 48 hr from grafting in allografted livers. The metabolic studies performed for 2 months revealed a significant correlation between well-maintained metabolic functions and transplant survival. On the contrary, an important energy loss was evidenced in livers of group 5, at the time of rejection.     

Role of immunosuppression in recurrence after liver transplantation for diethylnitrosamine-induced tumors in rats

Abstract Hepatocellular carcinoma is one of the world's most common malienant diseases, with an increasing incidence related to liver cirrhosis. The purpose of the study was to evaluate the role of immunosuppression in recurrence in rats transplanted after liver tumor induction by diethylnitrosamine (DENA), which has proved to be a reliable carcinogen. In 14-week-old Lewis rats weighing 200 g, tumors were induced by the oral administration (5 mg/100 ml in drinking water ad libitum) of DENA for 13 weeks. Orthotopic liver transplantation (OLT) was performed after 4 weeks' latency. In the Lewis/Lewis rats weighing 200 g, tumors sporin A (CsA) treatment, median survival was 199-days with no recurrence or metastasis. In the BN/Lewis group with no CsA (5 ats) median survival was 144 days. All rats died due to rejection. In the other BN/Lewis group (10 rats), OLT was followed by CsA administration (7.5 mg/kg). Median survival was 161 days. In three rats (218 days), there was liver tumor recurrence; in two rats (137.5 days), kidney and lung metastases were found. The remaining rats died of septic complications. In the Lewis/Lewis + CsA group (10 rats), median survival was 131 days with 5 recurrencies and/or metastases. Two rats are still surviving at 84 and 88 days. Our results suggest that the DENA model is reliable; it proved to have a similar carcinologic pattern to HCC in man. Moreover, immunosuppression seems to play an important role in determining recurrence. Further studies are needed to investigate the efficacy of chemotherapy agents pre- and post-transplantation.     

Mechanisms of cyclophosphamide-induced tolerance to IE-encoded alloantigens--evidence of clonal deletion in MHC antigen-reactive cells for skin allograft rejection.

Transplantation tolerance across H-2D plus IE antigen barriers has been achieved when B10.Thy1.1 (Kb, IAb, IE-, Db; Thy1.1) mice were primed i.v. with 9 x 10(7) spleen cells plus 3 x 10(7) bone marrow cells from B10.A(5R) (Kb, IAb, IEb, Dd; Thy1.2) and treated i.p. with 200 mg/kg of cyclophosphamide (CP) two days later. The tolerant state was confirmed by prolonged acceptance of donor-type skin grafts, and in vitro unresponsiveness to donor antigens. From the early stage of tolerant state, V beta 11+ or V beta 5+ T cells expressing CD4 or CD8 accessory molecules were markedly decreased in the periphery of the tolerant mice. Moreover, neither CD4+CD8- nor CD4-CD8+ thymocytes bearing a high density of V beta 11 or V beta 5 were detected in the chimeric thymus. The intrathymic clonal deletion appeared to be maintained in some of the recipient mice even after the disappearance of detectable mixed chimerism in the late stage. These results suggest that the mechanisms of the CP-induced tolerance include the destruction of the IE (and probably H-2D) reactive T cells in the periphery followed by the intrathymic clonal deletion of T cells reactive against these antigens. These results directly show the strong correlation between transplantation tolerance to H-2 alloantigens and the disappearance of alloreactive T cells in both the periphery and thymus.     

单已基甘氨酰二甲苯胺评估肝脏储备功能的实验研究

目的 通过检测大鼠肝损害不同阶段的血清单乙基甘氨酰二甲苯胺(MEGX),血清支链氨基酸/芳香氨基酸(BCAA/AAA)比值,探究能够敏感反映肝脏组织病理变化的肝储备功能指标.方法 将雄性Wistar大鼠40只分为实验组和对照组,实验组大鼠皮下注射60%四氯化碳橄榄油溶液,对照组则注射生理盐水橄榄油混合液,制备不同时期大鼠肝损害模型,分别在肝损害不同阶段检测血清MEGX,血清BCAA/AAA,常规肝功能,病理组织学检查.结果 随着肝细胞损害程度的加重,大鼠血清MEGX浓度逐级隆低,与肝组织病理学变化较相符;BCAA/AAA亦可反映肝损害的程度,但不及MEGX敏感;而常规肝功能试验与肝组织学变化不相符.结论 测定血清MEGX水平比检测血清BCAA/AAA能够更敏感的反映肝组织病理变化,是评估肝储备功能的较好指标.     

Mechanisms of working memory dysfunction after mild and moderate TBI: evidence from functional MRI and neurogenetics

Cognitive complaints are a frequent source of distress and disability after mild and moderate traumatic brain injury (TBI). While there are deficits in several cognitive domains, many aspects of these complaints and deficits suggest that problems in working memory (WM) play an important role. Functional imaging studies in healthy individuals have outlined the neural substrate of WM and have shown that regions important in WM circuitry overlap with regions commonly vulnerable to damage in TBI. Use of functional MRI (fMRI) in individuals with mild and moderate TBI suggests that they can have problems in the activation and allocation of WM, and several lines of evidence suggest that subtle alterations in central catecholaminergic sensitivity may underlie these problems. We review the evidence from fMRI and neurogenetic studies that support the role of catecholaminergic dysregulation in the etiology of WM complaints and deficits after mild and moderate TBI.     

预输注供者凋亡的脾细胞诱导大鼠肝移植免疫耐受的研究

目的探讨肝移植预输注地塞米松体内诱导凋亡的供体脾细胞诱导受体肝移植免疫耐受可能性。方法实验分5组,对照组,单纯供体地塞米松处理组,单纯输供者脾细胞组,地塞米松诱导供者凋亡脾细胞输注组,第三品系组。每组均做Wistar至SD的肝移植,每组各10只Wistar、SD大鼠。用地塞米松3mg/(kg·d)处理Wistar大鼠3d后,第4天取供体的脾细胞输注受体,第10天行大鼠肝移植。观察术后第7天肝功能(ALT、TBil)的变化、病理改变和受体生存期。结果肝移植预输注凋亡细胞组的ALT、TBil较其它各组显著低(P<0·05);生存期明显长(P<0·05),病理改变较轻。结论肝移植预输注地塞米松体内诱导供体凋亡的脾细胞能诱导受体大鼠对移植肝的免疫耐受。     

Sirolimus-based immunosuppression in liver transplantation for hepatocellular carcinoma: a meta-analysis

Sirolimus (SRL) is a novel immunosuppressant with antitumor properties. We performed a meta-analysis to determine whether SRL can improve patient survival and decrease the risks of tumor recurrence in patients with a pretransplant diagnosis of hepatocellular carcinoma (HCC). We searched databases for controlled clinical trials assessing the survival and oncological benefits of SRL for liver transplant recipients with pretransplant HCC. Five studies with a total of 2950 participants were included in this study. In comparison with SRL-free regimens, SRL-based regimens improved overall survival at 1 [odds ratio (OR) = 4.53, 95% confidence interval (95% CI) = 2.31-8.89], 3 (OR = 1.97, 95% CI = 1.29-3.00), and 5 years (OR = 2.47, 95% CI = 1.72-3.55). The pooled results showed that in comparison with SRL-free regimens, SRL-based regimens decreased tumor recurrence (OR = 0.42, 95% CI = 0.21-0.83). No significant differences in the frequencies of episodes of major posttransplant complications were observed between the groups. In conclusion, SRL is generally safe and prolongs patient survival in liver transplant recipients with pretransplant HCC.     

Safety of minimal immunosuppression in liver transplantation for hepatoblastoma

Background

Despite aggressive chemotherapy, recurrence of disease remains the leading cause of death after liver transplantation (LTx) for hepatoblastoma (HB). Unfortunately, little is known about the effects of immunosuppression on recurrence and posttransplant outcomes. We hypothesized that minimal immunosuppression can be safely used in these recipients.

Methods

In 2004, we adopted a minimal immunosuppression regimen using daclizumab induction and tacrolimus monotherapy. Kaplan-Meier survival curves were generated.

Results

From 2004 to 2006, 6 children underwent primary LTx for HB with neoadjuvant and adjuvant chemotherapy. Patient survival was 100% at 12 months and at 24 months, without graft loss. One patient died 28 months after transplantation. Recurrence-free survival was 83% at 12 months and at 24 months. Despite minimal immunosuppression (IS), 4 of 6 HB recipients remained rejection-free. When compared to other LTx recipients receiving minimal IS, HB recipients trended to have better rejection-free survival (HB, 83% at 12 months and 62.5% at 24 months vs all others, 36% and 36%, respectively; P = .19).

Conclusion

Our short-term patient and graft survival rates are comparable to those reported for all HB recipients in the United Network for Organ Sharing database. Although not statistically significant, our rejection-free survival data suggest that HB recipients may be less likely to reject than other recipients.     

Establishment of fully xenogeneic (mouse-->rat) bone marrow chimeras: evidence for normal development and clonal deletion of mouse T cells

BACKGROUND: Xenotransplantation is a potential solution to the critical shortage of transplantable organs. However, conventional immunosuppressive agents do not control the vigorous cellular and humoral rejection across species disparities. The induction of donor specific tolerance via bone marrow chimerism may be a method to avoid xenograft rejection. In xenogeneic chimeras, T cell repertoire selection plays an important role in the induction of tolerance. Until now a model of mouse-->rat multilineage chimerism has not been reported. This study reports the establishment of fully xenogeneic mouse-->rat multilineage chimeras and evaluates the role of T cell development and repertoire selection in tolerance induction in a xenogeneic environment. METHODS: Recipient rats were irradiated at a dose of total body irradiation ranging between 800-1100 cGy and injected with 120-300x10(6) donor mouse bone marrow cells. Chimeras were typed for engraftment at 4 weeks and then monthly thereafter. T cell repertoire was evaluated in chimeras using two-color flow cytometry and monoclonal antibodies directed against the variable portion of the beta chain of the T cell receptor. RESULTS: Fully xenogeneic multilineage bone marrow chimerism was produced in a mouse-->rat model by using ablative radiation and a high dose of donor cells. Mouse T cells develop in a phenotypically normal fashion in chimeric rats and the host rat is capable of deleting T cells that are reactive to the donor mouse strain. CONCLUSION: Long-term multilineage bone marrow chimerism can be produced in a mouse-->rat bone marrow transplant model. Mouse T cells develop in a phenotypically normal fashion and negative selection of specific T cell receptor-Vbeta occurs in a xenogeneic environment in a predictable fashion paralleling that for syngeneic or allogeneic transplantation.     

A useful model to audit liver resolution from cirrhosis in rats using functional proteomics

BACKGROUND: We conducted a rat cirrhosis and recovery model, on the basis of which proteomics was used to audit liver resolution from cirrhosis. MATERIALS AND METHODS: Micronodular cirrhosis was established using Sprague-Dawley rats fed thioacetamide, and spontaneous recovery from cirrhosis was acquired after thioacetamide withdrawal. RESULTS: Over the course of a 2-, 3-, and 6-week recovery, macronodular cirrhosis, uneven liver surface, and nearly normal liver surface were acquired, respectively. Specific liver enzymes, hepatitis activity index, hepatocytes apoptosis index, number of activated Kupffer cells and hepatic stellate cells, and area of fibrosis bands consistently peaked at the end of thioacetamide administration and decreased progressively during the recovery period. mRNA expression of proinflammatory cytokines and proapoptotic molecules peaked around the end of thioacetamide administration and decreased thereafter. Using two-dimensional gel electrophoresis, the seven most upregulated and six most downregulated protein spots were analyzed by matrix-assisted laser desorption/ionization time-of-flight. Of these, GST-P2 and its isoforms, GST-alpha and GST-M, were chosen for further validation using immunohistochemistry. Expression of GST-P peaked at the 2-week recovery, whereas GST-alpha and GST-M remained at strong levels at the 6-week recovery. CONCLUSIONS: The mechanism of resolution from cirrhosis can be extensively investigated using the presented model which, for example, showed GST isoforms performing their roles at different time phases.     

Mechanisms of hierarchical reinforcement learning in cortico-striatal circuits 2: evidence from fMRI

The frontal lobes may be organized hierarchically such that more rostral frontal regions modulate cognitive control operations in caudal regions. In our companion paper (Frank MJ, Badre D. 2011. Mechanisms of hierarchical reinforcement learning in corticostriatal circuits I: computational analysis. 22:509-526), we provide novel neural circuit and algorithmic models of hierarchical cognitive control in cortico-striatal circuits. Here, we test key model predictions using functional magnetic resonance imaging (fMRI). Our neural circuit model proposes that contextual representations in rostral frontal cortex influence the striatal gating of contextual representations in caudal frontal cortex. Reinforcement learning operates at each level, such that the system adaptively learns to gate higher order contextual information into rostral regions. Our algorithmic Bayesian "mixture of experts" model captures the key computations of this neural model and provides trial-by-trial estimates of the learner's latent hypothesis states. In the present paper, we used these quantitative estimates to reanalyze fMRI data from a hierarchical reinforcement learning task reported in Badre D, Kayser AS, D'Esposito M. 2010. Frontal cortex and the discovery of abstract action rules. Neuron. 66:315--326. Results validate key predictions of the models and provide evidence for an individual cortico-striatal circuit for reinforcement learning of hierarchical structure at a specific level of policy abstraction. These findings are initially consistent with the proposal that hierarchical control in frontal cortex may emerge from interactions among nested cortico-striatal circuits at different levels of abstraction.     

Mechanisms of joint damage in gout: evidence from cellular and imaging studies

The clinical course of gout is initially characterized by acute self-limited joint inflammation, but long-standing disease is often associated with chronic inflammation followed by the development of erosive joint damage, which can result in long-term functional impairment. Preventing joint damage is now a major focus of therapeutic intervention in gout. New light has been shed on the mechanisms leading to cartilage and bone damage in patients with this disease. Here, we discuss basic science studies focusing on the cellular immunology of bone and cartilage in gout and the effects of monosodium urate crystals on signaling pathways, cytokine release and the function of osteoclasts, osteoblasts and chondrocytes. We then explore the use of advanced imaging modalities (including MRI, ultrasonography, CT and dual-energy CT) to investigate pathology in gout, as they provide new ways to visualize joint tissues. These modalities vary in their ability to detect the various pathological features of gout and have different clinical applications. Imaging provides information about the inflammatory nature of the joint lesion, position and size of tophaceous deposits, and extent of bone and cartilage damage. Imaging is also increasingly being used to monitor the progression of joint damage and regression of tophi with effective urate-lowering therapy.     

Limb allotransplantation in rats: combined immunosuppression by FK-506 and 15-deoxyspergualin.

The immunosuppressive effect of combined therapy using FK-506 and 15-deoxyspergualin was investigated in rat limb allotransplantation. The right hindlimb of an inbred Dark Agouti rat (RT1a) was transplanted to a Lewis rat (RT1l) and observed for 120 days. Eighty-eight transplantations were performed. Rejection of the grafts was evaluated histologically as well as macroscopically. A pathologic grading system was used to rate the severity of rejection. Limb survival time in Lewis rats receiving FK-506 therapy for days was significantly prolonged by combined therapy with 15-deoxyspergualin. Histologic study showed practically no rejection in all the graft-composing tissues except the skin and bone marrow, in which there was rejection. These results suggest that tissues like bone, cartilage, and muscle may survive transplantation with short-term combination FK-506 and 15-deoxyspergualin therapy even after withdrawal of both agents.     

Allograft acceptance and rejection, mediated by a liver suppressor factor, LSF-1, purified from serum of liver transplanted rats

In certain rat strain combinations liver allografts are spontaneously accepted without immunosuppression and induce donor-specific tolerance to further skin and heart grafts in the recipient. Such an effect is also transferrable using serum from orthotopically liver transplanted rats (OLT serum). In the OLT serum of one such combination. DA (RT1^a) donor into PVG (RT1^c) recipient, a 40 kDa protein (liver suppressor factor, LSF-1) has been identified and shown to be immunosupressive in vitro. The aim of the present study is to investigate the immunological effect of LSF-1 and a polyclonal antibody (anti-LSF-1) against this molecule, in a rat heterotopic heart transplant (HHT) model and OLT model, respectively. Intramuscular injection of 300 μg of LSF-1, 1 h postoperatively, into a PVG recipient of either a DA or BN (RT1ⁿ) cardiac allograft caused significant prolongation of graft survival. Intravenous injection of polyclonal rabbit sera raised against an N-terminal peptide of LSF-1 (anti-LSF-1), within 1 h postoperatively, had variable effects on the survival of DA liver grafts in PVG recipients. In cases injection of between 1 and 2 ml of anti-LSF-1 resulted in death of the recipient. Histological examination of the liver showed severe rejection with lymphoid cell infiltration of the portal tract and sinusoids and extensive damage to the parenchyma. All control rats survived for more than 60 days without any signs of rejection. The anti-LSF-1 polyclonal antibody prevented the induction of tolerance in the normally tolerogenic model (DA into PVG). This, together with the in vivo results, suggests a role for LSF-1 in the induction of tolerance.     

人肝癌转移抑制基因存在的功能研究

目的 寻求人8号染色体上存在肝癌转移抑制基因的功能证据.方法 前期通过微细胞介导的染色体转移方法(MMCT),将正常人8号染色体导入到大鼠肝癌高转移细胞株C5F中获得的微细胞杂交克隆Ne08/C5F-1～10和大鼠肝癌细胞株CSF,分别被接种到6～7周龄雌性BALB/CA裸鼠皮下进行自发转移实验,观察皮下成瘤及肺部大体转移灶形成情况,肺组织连续切片并计数镜下转移灶,结果进行单因素方差分析.结果 所有微细胞杂交克隆均能皮下成瘤,微细胞杂交克隆的自发转移实验发现有6个杂交克隆出现肺转移表型的明显抑制(P<0.05),其中2个杂交克隆肺转移表型发生完全抑制.结论 人8号染色体对大鼠肝癌高转移细胞株CSF的成功导入改变了CSF的转移表型,提供了人8号染色体上存在肝癌转移抑制基因的直接的功能证据.