Search PubMed⌕ Search

Biomedical subjects

Robert J Porte

Publications and source records attributed to Robert J Porte.

At least 19 recordsLinked to original sources
PubMed2006

Causes and consequences of ischemic-type biliary lesions after liver transplantation.

Biliary complications are a major source of morbidity, graft loss, and even mortality after liver transplantation. The most troublesome are the so-called ischemic-type biliary lesions (ITBL), with an incidence varying between 5% and 15%. ITBL is a radiological diagnosis, characterized by intrahepatic strictures and dilatations on a cholangiogram, in the absence of hepatic artery thrombosis. Several risk factors for ITBL have been identified, strongly suggesting a multifactorial origin. The main categories of risk factors for ITBL include ischemia-related injury; immunologically induced injury; and cytotoxic injury, induced by bile salts. However, in many cases no specific risk factor can be identified. Ischemia-related injury comprises prolonged ischemic times and disturbance in blood flow through the peribiliary vascular plexus. Immunological injury is assumed to be a risk factor based on the relationship of ITBL with ABO incompatibility, polymorphism in genes coding for chemokines, and pre-existing immunologically mediated diseases such as primary sclerosing cholangitis and autoimmune hepatitis. The clinical presentation of patients with ITBL is often not specific; symptoms may include fever, abdominal complaints, and increased cholestasis on liver function tests. Diagnosis is made by imaging studies of the bile ducts. Treatment starts with relieving the symptoms of cholestasis and dilatation by endoscopic retrograde cholangiopancreaticography (ERCP) or percutaneous transhepatic cholangiodrainage (PTCD), followed by stenting if possible. Eventually up to 50% of the patients with ITBL will require a retransplantation or may die. In selected patients, a retransplantation can be avoided or delayed by resection of the extra-hepatic bile ducts and construction of a hepaticojejunostomy. More research on the pathogenesis of ITBL is needed before more specific preventive or therapeutic strategies can be developed.

Bile Duct Diseases↗
PubMed2006

Bile salt toxicity aggravates cold ischemic injury of bile ducts after liver transplantation in Mdr2+/- mice.

Intrahepatic bile duct strictures are a serious complication after orthotopic liver transplantation (OLT). We examined the role of endogenous bile salt toxicity in the pathogenesis of bile duct injury after OLT. Livers from wild-type mice and mice heterozygous for disruption of the multidrug resistance 2 Mdr2 gene (Mdr2+/-) were transplanted into wild-type recipient mice. Mdr2+/- mice secrete only 50% of the normal amount of phospholipids into their bile, leading to an abnormally high bile salt/phospholipid ratio. In contrast to homozygous Mdr2-/- mice, the Mdr2+/- mice have normal liver histology and function under normal conditions. Two weeks after OLT, bile duct injury and cholestasis were assessed by light and electron microscopy, as well as through molecular and biochemical markers. There were no signs of bile duct injury or intrahepatic cholestasis in liver grafts from wild-type donors. Liver grafts from Mdr2+/- donors, however, had enlarged portal tracts with cellular damage, ductular proliferation, biliostasis, and a dense inflammatory infiltrate after OLT. Parallel to this observation, recipients of Mdr2+/- livers had significantly higher serum transaminases, alkaline phosphatase, total bilirubin, and bile salt levels, as compared with recipients of wild-type livers. In addition, hepatic bile transporter expression was compatible with the biochemical and histological cholestatic profile found in Mdr2+/- grafts after OLT. In conclusion, toxic bile composition, due to a high biliary bile salt/phospholipid ratio, acted synergistically with cold ischemia in the pathogenesis of bile duct injury after transplantation.

ATP Binding Cassette Transporter, Subfamily B↗
PubMed2006

Anastomotic biliary strictures after liver transplantation: causes and consequences.

We retrospectively studied the prevalence, presentation, results of treatment, and graft and patient survival of grafts developing an anastomotic biliary stricture (AS) in 531 adult liver transplantations performed between 1979 and 2003. Clinical and laboratory information was obtained from the hospital files, and radiological studies were re-evaluated. Twenty-one possible risk factors for the development of AS (variables of donor, recipient, surgical procedure, and postoperative course) were analyzed in a univariate and stepwise multivariate model. Forty-seven grafts showed an anastomotic stricture: 42 in duct-to-duct anastomoses, and 5 in hepaticojejunal Roux-en-Y anastomoses. The cumulative risk of AS after 1, 5, and 10 years was 6.6%, 10.6%, and 12.3% respectively. Postoperative bile leakage (P = 0.001), a female donor/male recipient combination (P = 0.010), and the era of transplantation (P = 0.006) were independent risk factors for the development of an AS. In 47% of cases, additional (radiologically minor) nonanastomotic strictures were diagnosed. All patients were successfully treated by 1 or more treatment modalities. As primary treatment, endoscopic retrograde cholangiopancreaticography (ERCP) was successful in 24 of 36 (67%) cases and percutaneous transhepatic cholangiodrainage in 4 of 11 (36%). In the end 15 patients (32%) were operated, all with long-term success. AS presenting more than 6 months after transplantation needed more episodes of stenting by ERCP, and more stents per episode compared to those presenting within 6 months and recurred more often. Graft and patient survival were not impaired by AS.

Adolescent↗
PubMed2006

Surgical injuries of postmortem donor livers: incidence and impact on outcome after adult liver transplantation.

The exact frequency and clinical consequences of surgical hepatic injuries during organ procurement are unknown. We analyzed the incidence, risk factors, and clinical outcome of surgical injuries in 241 adult liver grafts. Hepatic injuries were categorized as parenchymal, vascular, or biliary. Outcome variables were bleeding complications, hepatic artery thrombosis (HAT), and graft survival. In 82 livers (34%), 96 injuries were detected. Most injuries were minor, but clinically relevant injuries were detected in 6.6% (16/241) of the livers. Fifty (21%) liver grafts had some degree of parenchymal or capsular injury, 40 (17%) had vascular injury, and 6 (2%) had an injury to the bile duct. Procurement region was the only risk factor significantly associated with surgical injury. The rate of hepatic artery injury was significantly higher in livers with aberrant arterial anatomy. Bleeding complications were found in 18% of patients who received livers with a parenchymal or capsular injury in contrast to 9% without parenchymal injury (P = 0.065). HAT was found in 23% of the patients who received a liver with arterial injury compared to 4% without arterial injury (P = 0.001). Overall graft survival rates were not significantly different for grafts with or without anatomical injury. In conclusion, surgical injuries of donor livers are an underestimated problem in liver transplantation and can be observed in about one-third of all cases. Clinically relevant injuries are detected in 6.6% of all liver grafts. Arterial injuries are associated with an increased risk of HAT.

Adult↗
PubMed2006

Spatiotemporal expression of heme oxygenase-1 detected by in vivo bioluminescence after hepatic ischemia in HO-1/Luc mice.

Upregulation of heme oxygenase-1 (HO-1) has been proposed as a critical mechanism protecting against cellular stress during liver transplantation, providing a potential target for new therapeutic interventions. We investigated the feasibility of in vivo bioluminescence imaging (BLI) to noninvasively quantify the spatiotemporal expression of HO-1 after warm hepatic ischemia in living animals. Luciferase activity was measured by BLI as an index of HO-1 transcription in transgenic reporter mice (Ho1-luc) at standardized time points after 60 minutes of warm hepatic ischemia. HO-1 mRNA levels were measured in postischemic livers of mice sacrificed at the same time points in separate experiments. Bioluminescent signals from postischemic liver lobes were first detected at 3 hours after reperfusion. Peak levels were reached at 9 hours, after which bioluminescent activity declined and returned to baseline values at 48 hours after reperfusion. Upregulation of HO-1 as detected by in vivo BLI was preceded by increased HO-1 mRNA expression and confirmed by enhanced immunohistochemical staining of hepatocytes. In conclusion, this study shows that in vivo BLI allows a sensitive assessment of HO-1 expression after hepatic ischemia in living animals. The capability of whole-body temporal imaging of HO-1 expression provides a valuable tool in the development of novel strategies to modulate HO-1 expression in liver transplantation.

Animals↗
PubMed2006

Fluordeoxyglucose positron emission tomography contributes to management of pediatric liver transplantation candidates with fever of unknown origin.

Fever of unknown origin (FUO) frequently complicates the management of pediatric patients with terminal chronic liver failure during the pretransplantation period and may lead to increased morbidity and mortality. Nonhepatic origins of systemic infections may render the patient unsuitable for transplantation whereas infections within the liver may require organ resection for a cure. Therefore, accurate localization of the infection focus is critical for optimal management of children on the waiting list for liver transplantation. Here we report our experience using [18 F]fluordeoxyglucose (FDG)-positron emission tomography (PET) to detect the origin of infection in 11 children with biliary cirrhosis presenting with FUO during the waiting period for liver transplantation. In 5 children, positive intrahepatic FDG-PET signals correlated with bacterial cultures of the excised liver and/or anatomic or histologic signs of infection. Based on the FDG-PET findings, these patients underwent transplantation after continuous antibiotic treatment with ongoing, recurrent episodes of fever. In 6 children, no abnormal hepatic FDG-PET signals were found and no infections could be detected in the liver. Transplantation in these patients was performed only after becoming afebrile. Standard imaging techniques did not reveal abnormalities compatible with infection in any of the children. In conclusion, in children with biliary cirrhosis and FUO on the waiting list for liver transplantation, information obtained by FDG-PET imaging may be useful for decisions on therapy and suitability for liver transplantation.

Anti-Bacterial Agents↗
PubMed2006

Biliary complications after liver transplantation: a review.

After liver transplantation, the prevalence of complications related to the biliary system is 6-35%. In recent years, the diagnosis and treatment of biliary problems has changed markedly. The two standard methods of biliary reconstruction in liver transplant recipients are the duct-to-duct choledochocholedochostomy and the Roux-en-Y-hepaticojejunostomy. Biliary leakage occurs in approximately 5-7% of transplant cases. Leakage from the site of anastomosis, the T-tube exit site and donor or recipient remnant cystic duct is well described. Symptomatic bile leakage should be treated by stenting of the duct by endoscopic retrograde cholangiopancreatography (ERCP) or percutaneous transhepatic cholangiography (PTCD). Biliary strictures can occur at the site of the anastomosis (anastomotic stricture; AS) or at other locations in the biliary tree (non-anastomotic strictures; NAS). AS occur in 5-10% of cases and are due to fibrotic healing. Treatment by ERCP or PTCD with dilatation and progressive stenting is successful in the majority of cases. NAS can occur in the context of a hepatic artery thrombosis, or with an open hepatic artery (ischaemic type biliary lesions or ITBL). The incidence is 5-10%. NAS has been associated with various types of injury, e.g. macrovascular, microvascular, immunological and cytotoxic injury by bile salts. Treatment can be attempted with multiple sessions of dilatation and stenting of stenotic areas by ERCP or PTCD. In cases of localized diseased and good graft function, biliary reconstructive surgery is useful. However, a significant number of patients will need a re-transplant. When biliary strictures or ischaemia of the graft are present, stones, casts and sludge can develop.

Anastomosis, Roux-en-Y↗
PubMed2006

Analysis of differences in outcome of two European liver transplant centers.

Authors analyzed the differences in the outcome of two European liver transplant centers differing in case volume and experience. The first was the Transplantation and Surgical Clinic, Semmelweis University, Budapest, Hungary (SEB) and the second the University Medical Center Groningen, Groningen, The Netherlands (UMCG). We investigated if such differences could be explained. The 1-, 3- and 5-year patient survival in the UMCG was 86%, 80%, and 77% compared with 65%, 56%, and 55% in SEB. Graft survival at the same time points was 79%, 71%, and 66% in the UMCG and 62%, 55%, and 53% in SEB. Significant differences were present regarding the donor and recipient age, diagnosis mix, disease severity and operation variables, per-operative transfusion rate, vascular complications, postoperative infection rate, and need for renal replacement. To determine factors correlating with survival, a separate uni- and multivariate analysis was performed in each center individually, between study parameters and patient survival. In both centers, peri-operative red blood cell (RBC) transfusion rate was a significant predictor for patient survival. The difference in blood loss can be explained by different operation techniques and shorter operation time in SEB, with consequently less time spent on hemostasis. It was jointly concluded that measures to reduce blood loss by adapting the operation technique might lead to improved survival and reduced morbidity.

Adolescent↗
PubMed2006

Recombinant factor VIIa in patients with coagulopathy secondary to anticoagulant therapy, cirrhosis, or severe traumatic injury: review of safety profile.

BACKGROUND: In recent years, the hemostatic agent recombinant factor VIIa (rFVIIa) has emerged as a potentially new therapeutic agent for management of coagulopathy in patients with cirrhosis or following severe traumatic injury, a complex problem for clinicians in which standard treatment strategies are not always effective. As with other hemostatic agents, a primary safety concern of rFVIIa therapy is the theoretical possibility that systemic administration could confer an increased risk of thrombotic complications. So far, clinical experience indicates rFVIIa to be a safe treatment for currently approved indications within hemophilia. Little information is available, however, for patient populations outside this clinical setting. STUDY DESIGN AND METHODS: This article reviews critical safety data obtained from 13 Novo Nordisk-sponsored clinical trials of rFVIIa in patients with coagulopathy secondary to anticoagulant therapy, cirrhosis, or severe traumatic injury. RESULTS: Thrombotic adverse events were reported for 5.3 percent (23/430) of placebo-treated patients and 6.0 percent (45/748) of patients on active treatment. No significant difference was found between placebo-treated and rFVIIa-treated patients with respect to the incidence of thrombotic AEs, either on an individual trial basis or for these trial populations combined (p=0.57). CONCLUSION: An important determinant for the safety profile reported here is likely to be the specific mechanism of action of rFVIIa, shown in experimental studies to be localized to the site of vascular injury where tissue factor is exposed.

Anticoagulants↗
PubMed2005

P53 mutation analysis of colorectal liver metastases: relation to actual survival, angiogenic status, and p53 overexpression.

PURPOSE: To correlate TP53 mutations with angiogenic status of the tumor and prognosis after liver surgery in patients with colorectal liver metastases and to correlate immunohistochemical staining of p53 protein with TP53 gene mutations. EXPERIMENTAL DESIGN: Tumors of 44 patients with surgically treated colorectal liver metastases were analyzed for (a) TP53 mutations using denaturing gradient gel electrophoresis followed by sequencing, (b) microvessel density using the hot spot overlap technique, (c) apoptotic rate in tumor cells and endothelial cells of tumor microvessels using double immunostaining for anti-cleaved caspase 3 and anti-CD34, and (d) expression of p53 protein using immunohistochemistry. RESULTS: TP53 mutations were detected in 36% of the metastases and occurred more frequently in liver metastases from left-sided colon tumors than from right-sided colon tumors (P = 0.04). In metastases with TP53 mutations, microvessel density was higher compared with tumors with wild-type p53. Endothelial cell apoptosis was not different in tumor microvessels from TP53-mutated versus nonmutated tumors. The 5-year actual survival was not influenced by TP53 mutational status, microvessel density, or endothelial cell apoptotic rate of the tumors. Based on immunohistochemical p53 overexpression, the positive and negative predictive values of TP53 mutations were 61% and 82%. CONCLUSIONS: In patients with surgically treated colorectal liver metastases, TP53 mutations and angiogenic status did not influence prognosis. Immunohistochemistry is not a reliable technique for detecting TP53 mutations.

Aged↗
PubMed2005

Hepatic expression of ABC transporters G5 and G8 does not correlate with biliary cholesterol secretion in liver transplant patients.

The adenosine triphosphate (ATP)-binding cassette (ABC)-transporters ABCG5 and ABCG8 have been shown to mediate hepatic and intestinal excretion of cholesterol. In various (genetically modified) murine models, a strong relationship was found between hepatic expression of ABCG5/ABCG8 and biliary cholesterol content. Our study aimed to relate levels of hepatic expression of ABCG5 and ABCG8 to biliary excretion of cholesterol in man. From 24 patients who had received a liver transplant, bile samples were collected daily after transplantation over a 2-week period to determine biliary composition. Expression of ABCG5, ABCG8, MDR3, and BSEP was assessed by real-time polymerase chain reaction (PCR) in liver biopsy specimens collected before and after transplantation. Levels of hepatic ABCG5, ABCG8, and MDR3 messenger RNA (mRNA) were strongly correlated. After transplantation, the biliary secretion rate of cholesterol continuously increased, coinciding with gradual increases in bile salt and phospholipid secretion. In contrast, hepatic levels of ABCG5 and ABCG8 mRNA remained unchanged. Surprisingly, no correlation was found between the hepatic expression of ABCG5 and ABCG8 and rates of biliary cholesterol secretion, normalized for biliary phospholipid secretion. As expected, the concentration of biliary phospholipids correlated well with MDR3 expression. In conclusion, the strong relationship between ABCG5 and ABCG8 gene expression is consistent with the coordinate regulation of both genes, and in line with heterodimerization of both proteins into a functional transporter. Hepatic ABCG5/ABCG8 expression, at least during the early phase after transplantation, is not directly related to biliary cholesterol secretion in humans. This finding suggests the existence of alternative pathways for the hepatobiliary transport of cholesterol that are not controlled by ABCG5/ABCG8.

ATP Binding Cassette Transporter, Subfamily B↗
PubMed2005

Safety and efficacy of a single bolus administration of recombinant factor VIIa in liver transplantation due to chronic liver disease.

Orthotopic liver transplantation (OLT) can be associated with excessive blood loss. As a result, there may be increased risk of adverse outcomes. Activated recombinant factor VII (rFVIIa) has demonstrated the ability to improve hemostasis in a variety of disorders; however, there has been a limited amount of research into its use in OLT. The purpose of this dose-finding study was to examine the efficacy and safety of rFVIIa in the reduction of bleeding in patients undergoing OLT. In this double-blind trial, patients with end-stage liver disease scheduled for OLT were randomized to 1 of 4 parallel study groups. They received a single intravenous bolus of rFVIIa (20, 40, or 80 microg/kg) or placebo prior to surgery. The primary assessment endpoint was the total number of red blood cell (RBC) units transfused perioperatively. Safety was evaluated by adverse events reported. Eighty-three comparable patients were randomized to receive study product, with 82 ultimately undergoing OLT. There were no significant differences in required RBC units between the placebo and rFVIIa study groups. The number of adverse events was comparable between study groups. In conclusion, rFVIIa has a good safety profile in patients undergoing OLT. However, the doses studied did not have any effect on the number of RBC transfusions required.

Adult↗
PubMed2005

Sequential and simultaneous revascularization in adult orthotopic piggyback liver transplantation.

The aim of the study was to assess whether there is a difference in outcome after sequential or simultaneous revascularization during orthotopic liver transplantation (OLT) in terms of patient and graft survival, mortality, morbidity, and liver function. The study population consisted of 102 adult patients with primary full-size piggyback OLT transplanted between January 1998 and December 2001. In 71 patients (70%) the grafts were sequentially reperfused after completion of the portal vein anastomosis and subsequent arterial reconstruction was performed (sequential reperfusion [SeqR] group). In 31 patients (30%) the graft was reperfused simultaneously via the portal vein and hepatic artery (simultaneous reperfusion [SimR] group). Patient and graft survival at 1, 3, and 6 months and at 1 year did not differ between the SeqR group and the SimR group. The red blood cell (RBC) requirements were significantly higher in the SimR group (5.5 units; range 0-20) in comparison to the SeqR group (2 units; range 0-19) (P = 0.02). Apart from a higher number of biliary anastomotic complications and abdominal bleeding complications in the SimR group in comparison to the SeqR group (13% vs. 2% and 19% vs. 6%, respectively; P = 0.06), morbidity was not different between the groups. No differences between the groups were observed regarding the incidence of primary nonfunction (PNF), intensive care unit stay, and acute rejection. This was also true for the severity of rejections. Postoperative recuperation of liver function was not different between the groups. In conclusion, no advantage of either of the 2 reperfusion protocols could be observed in this analysis, especially with respect to the incidence of ischemic type biliary lesions (ITBL).

Adolescent↗
PubMed2005

The effect of HLA mismatches, shared cross-reactive antigen groups, and shared HLA-DR antigens on the outcome after pediatric liver transplantation.

The aim of this study was to analyze the effect of human leukocyte antigen (HLA) class I and HLA-DR mismatching, sharing cross-reactive antigen groups (CREGs), and sharing HLA-DR antigens on the outcome after pediatric liver transplantation. Outcome parameters were graft survival, acute rejection, and portal fibrosis. A distinction was made between full-size (FSLTx) and technical-variant liver transplantation (TVLTx). A total of 136 primary transplants were analyzed. The effect of HLA on the outcome parameters was analyzed by adjusted multivariate logistic and Cox regression analysis. HLA mismatches, shared CREGs, and shared HLA-DR antigens affected neither overall graft survival nor survival after FSLTx. Survival after TVLTx was superior in case of 2 mismatches at the HLA-DR locus compared to 0 or 1 mismatch (P = 0.01) and in case of no shared HLA-DR antigen compared to 1 shared HLA-DR antigen (P = 0.004). The incidence of acute rejection was not influenced by HLA. The incidence of portal fibrosis could be analyzed in 62 1-yr biopsies and was higher after TVLTx than FSLTx (P = 0.04). The incidence of portal fibrosis after TVLTx with 0 or 1 mismatch at the HLA-DR locus was 100% compared to 43% with 2 mismatches (P = 0.004). After multivariate analysis, matching for HLA-DR and matching for TVLTx were independent risk factors for portal fibrosis. In conclusion, an overall beneficial effect of HLA matching, sharing CREGs, or sharing HLA-DR antigens was not observed. A negative effect was present for HLA-DR matching and sharing HLA-DR antigens on survival after TVLTx. HLA-DR matching might be associated with portal fibrosis in these grafts.

Adolescent↗