Marcos Silva

Hepatic venous reconstruction in pediatric living‐related donor liver transplantation – Experience of a single center

Abstract:u2002 In pediatric patients submitted to living related liver transplantation, hepatic venous reconstruction is critical because of the diameter of the hepatic veins and the potential risk of twisting of the graft over the line of the anastomosis. The aim of the present study is to present our experience in hepatic venous reconstruction performed in pediatric living related donor liver transplantation. Fifty‐four consecutive transplants were performed and two methods were utilized for the reconstruction of the hepatic vein: direct anastomosis of the orifice of the donor left or left and middle hepatic veins and the common orifice of the recipient left and middle hepatic veins (group 1–26 cases), and wide triangular anastomosis after creating a wide triangular orifice in the recipient inferior vena cava at the confluence of all the hepatic veins with an additional longitudinal incision in the inferior angle of the orifice (group 2–28 cases). In group 1, eight patients were excluded because of graft problems in the early postoperative period and five among the remaining 18 patients (27.7%) presented stricture at the site of the hepatic vein anastomosis. All these patients had to be submitted to two or three sessions of balloon dilatations of the anastomoses and in four of them a metal stent had to be placed. The liver histopathological changes were completely reversed by the placement of the stent. Among the 28 patients of the group 2, none of them presented hepatic vein stenosis (pu2003=u20030.01). The results of the present series lead to the conclusion that hepatic venous reconstruction in pediatric living donor liver transplantation must be preferentially performed by using a wide triangulation on the recipient inferior vena cava, including the orifices of the three hepatic veins. In cases of stenosis, the endovascular dilatation is the treatment of choice followed by stent placement in cases of recurrence.

Mycophenolate mofetil promotes prolonged improvement of renal dysfunction after pediatric liver transplantation: experience of a single center.

Abstract:u2002 Few studies have evaluated the long‐term use of MMF in liver transplanted children with renal dysfunction. The aim of this study is to report the experience of a pediatric transplantation center on the efficacy and security of long‐term use of a MMF immunosuppressant protocol with reduced doses of CNIs in stable liver transplanted children with renal dysfunction secondary to prolonged use of CsA or Tac. Between 1988 and 2003, 191 children underwent OLT and 11 patients developed renal dysfunction secondary to CNIs toxicity as evaluated by biochemical renal function parameters. The interval between liver transplantation and the introduction of the protocol varied from one to 12u2003yr. Renal function was evaluated by biochemical parameters in five phases: immediately prior to MMF administration; 3, 6, 12 and 24u2003months after the introduction of MMF. Among the patients, nine of them (82%) showed improvement of renal function parameters in comparison with the pretreatment values. The two patients that did not show any improvement were patients in whom the interval of time between OLT and the introduction of MMF was longer. All parameters of liver function remained unchanged. No episodes of acute or chronic rejection or increases in infection rates during the period were detected. Two patients developed transitory diarrhea and leukopenia that were reverted with reduction of MMF dosage. In conclusion, in liver transplanted pediatric patients with CNI‐induced chronic renal dysfunction, the administration of MMF in addition to reduced doses of CNIs promotes long‐term improvement in renal function parameters with no additional risks.

Successful treatment of de novo autoimmune hepatitis and cirrhosis after pediatric liver transplantation.

Abstract: Over a 15‐yr period of observation, among the 205 children who underwent liver transplantations, one of them developed a particular type of late graft dysfunction with clinical and histological similarity to autoimmune hepatitis. The patient had α1‐antitrypsin deficiency and did not previously have autoimmune hepatitis or any other autoimmune disease before transplantation. Infectious and surgical complications were excluded. After repeated episodes of unexplained fluctuations of liver function tests and liver biopsies demonstrating reactive or a biliary pattern, without any corresponding alteration of percutaneous cholangiography, a liver‐biopsy sample taken 4u2003yr after the transplant showed active chronic hepatitis progressing to cirrhosis, portal lymphocyte aggregates, and a large number of plasma cells. At that time, autoantibodies (gastric parietal cell antibody, liver–kidney microsomal antibody, and anti‐hepatic cytosol) were positive and serum IgG levels were high. Based on these findings of autoimmune disease, a diagnosis of ‘de novo autoimmune hepatitis’ was made. The treatment consisted of reducing the dose of cyclosporine, reintroduction of corticosteroids, and addition of mycophenolate mofetil. After 19 months of treatment, a new liver‐biopsy sample showed marked reduction of portal and lobular inflammatory infiltrate, with regression of fibrosis and of the architectural disruption. At that time, serum autoantibodies became negative. The last liver‐biopsy sample showed inactive cirrhosis and disappearance of interface hepatitis and of plasma cell infiltrate. Presently, 9u2003yr after the transplantation, the patient is doing well, with normal liver function tests and no evidence of cirrhosis. Her immunosuppressive therapy consists of tacrolimus, mycophenolate mofetil, and prednisolone. In conclusion, the present case demonstrates that de novo autoimmune hepatitis can appear in liver‐transplant patients despite appropriate anti‐rejection immunosuppression, and triple therapy with tacrolimus, mycophenolate mofetil, and prednisolone could sustain the graft and prevent retransplantation.

Management of biliary atresia in the liver transplantation era: a 15-year, single-center experience.

BACKGROUND/PURPOSEnThe aim of this study was to address the perioperative aspects of hepatoportoenterostomy (HPE) for biliary atresia (BA), through the study of a 15-year, single-center experience of the management of this disease.nnnMETHODSnOne hundred twenty-seven patients were divided into three groups, depending on the variant of HPE performed: group A (n = 53) underwent HPE with external diversion of the Roux-en-Y anastomosis; group B (n = 54) underwent HPE with a long (35 to 40 cm) Roux-en-Y anastomosis, without diversion; and group C (n = 20) underwent the same kind of HPE as group B, but with a modified, super extensive dissection of the porta hepatitis. Eleven children in group B had an intussusception type antireflux valve in the Roux-en-Y loop. The porta hepatitis of 105 children was histologically classified in types I to III and correlated with rate of postoperative bile flow and age at surgery. Liver transplantation was performed after HPE in 20 patients.nnnRESULTSnOverall, biliary drainage was achieved in 72.5% of the children after HPE and 26.8% of all patients became jaundice free. Porta hepatitis type III was associated with a significantly higher rate of biliary drainage post-HPE then types I and II. There was no difference in the rate of bile drainage, relative number of jaundice-free patients, and mean number of episodes of cholangitis per year among surgical groups A, B, C. In group A, 43.7% of the patients had complications related to the stoma. The actuarial survival of children who underwent HPE followed by liver transplantation was 85%.nnnCONCLUSIONSn(1) There is no correlation between type of porta hepatis and age at surgery for BA; (2) type III porta hepatis is associated with higher rates of bile drainage post-HPE; (3) children older than 16 weeks with BA should still be considered for HPE; (4) in these older patients, factors other than the type of porta hepatis, possibly the degree of liver damage, play a role in the lower rate of bile drainage observed; (5) external diversion of the Roux-en-Y in HPE is not beneficial and is detrimental because of stoma-related complications; (6) an antireflux valve in the Roux-en-Y loop does not reduce the incidence of cholangitis post-HPE; (7) Surgical reexploration does not restore biliary drainage; and (8) sequential therapy with HPE followed by liver transplantation remains the treatment of choice for BA.

Posterior reversible encephalopathy syndrome after liver transplantation in children: a rare complication related to calcineurin inhibitor effects.

Santos MM, Tannuri ACA, Gibelli NE, Ayoub AA, Maksoud‐Filho JG, Andrade WC, Velhote MCP, Silva MM, Pinho ML, Miyatani HT, Suzuki L, Tannuri U. Posterior reversible encephalopathy syndrome after liver transplantation in children: A rare complication related to calcineurin inhibitor effects.u2028Pediatr Transplantation 2011: 15:157–160.

Which is the best technique for hepatic venous reconstruction in pediatric living-donor liver transplantation? Experience from a single center

BACKGROUND/PURPOSEnThe introduction of the piggyback technique for reconstruction of the liver outflow in reduced-size liver transplants for pediatric patients has increased the incidence of hepatic venous outflow block (HVOB). Here, we proposed a new technique for hepatic venous reconstruction in pediatric living-donor liver transplantation.nnnMETHODSnThree techniques were used: direct anastomosis of the orifice of the donor hepatic veins and the orifice of the recipient hepatic veins (group 1); triangular anastomosis after creating a wide triangular orifice in the recipient inferior vena cava at the confluence of all the hepatic veins (group 2); and a new technique, which is a wide longitudinal anastomosis performed at the anterior wall of the inferior vena cava (group 3).nnnRESULTSnIn groups 1 and 2, the incidences of HVOB were 27.7% and 5.7%, respectively. In group 3, no patient presented HVOB (P = .001). No difference was noted between groups 2 and 3.nnnCONCLUSIONSnHepatic venous reconstruction in pediatric living-donor liver transplantation must be preferentially performed by using a wide longitudinal incision at the anterior wall of the recipient inferior vena cava. As an alternative technique, triangulation of the recipient inferior vena cava, including the orifices of the 3 hepatic veins, may be used.

An alternative method of arterial reconstruction in pediatric living donor liver transplantation with the recipient right gastroepiploic artery

Abstract:u2002 The classical method for arterial reconstruction in pediatric living donor liver transplantation using left lateral segment consists of end‐to‐end anastomosis between the donor left hepatic artery and the recipient right hepatic artery. In the present case, an intra‐operative hepatic artery thrombosis occurred because of extensive intima wall dissection of the recipient hepatic artery. The patient was a 6‐yr‐old boy with fulminant hepatic failure, who underwent living donor partial liver transplantation with left lateral segment from his father. The graft was irrigated by a left hepatic artery and an accessory left hepatic artery from gastric artery, both arteries with diameter of <2u2003mm. These arteries were anastomosed to the recipient right and left hepatic arteries, respectively. Before performing the bile duct reconstruction it was noted that these anastomoses were occluded by clots of blood. An extensive subintimal dissection of the recipient hepatic artery was the cause of this problem. The creation of a new anastomosis by using a more proximal part of this artery without subintimal dissection was judged impossible. Then, the right gastroepiploic artery was mobilized and an anastomosis was performed with the donor left hepatic artery in an end‐to‐end fashion. Arterial blood flow to the graft was established successfully and the patients postoperative recovery was excellent. Fifteen days after the transplantation, an angiotomography demonstrated a good hepatic arterial blood flow. The patient is now alive and well, 4u2003months after the transplantation. In conclusion, the method of hepatic graft arterialization described here is an important option for patients who undergo living donor or split liver transplantation.

A Framework for Authentication and Authorization Credentials in Cloud Computing

Security is a key concern when adopting cloud technology. Cloud solutions include not only issues inherited from related technologies, such as virtualization and distributed computing, but also new concerns associated to complexity of the cloud ecosystem, composed by the cloud entities and their interactions. One of the concerns is related to authentication and authorization in the cloud in order to provide robust mechanisms to identify entities and establish their permissions and roles in the cloud, controlling resource usage and promoting accounting and isolation. This paper identifies the state of the art in terms of credential management focusing on the cloud ecosystem. It proposes a credential classification and a framework for studying and developing solutions in this context, unifying concepts related to cloud deployment models, service types, entities and lifecycle controls.

Lightweight and escrow-less authenticated key agreement for the internet of things

Abstract Security is essential for wide wireless sensor network (WSN) deployments, such as the Internet of Things (IoT). However, the resource-constrained nature of sensors severely restricts the cryptographic algorithms and protocols that can be used in such platforms. Such restrictions apply especially to authenticated key agreement (AKA) protocols for bootstrapping keys between authorized nodes: in traditional networks, such schemes involve the transmission of quite large certificates and the execution of memory- and processing-intensive cryptographic algorithms, which are not suitable for WSNs. Whereas lightweight WSN-oriented schemes also exist, most of them focus on small deployments where key-escrow is possible (i.e., a fully trusted authority knows the private keys of all nodes). Aiming to identify AKA solutions suitable for the IoT scenario, in this article we assess lightweight and escrow-free schemes, evaluating their security and performance in terms of processing time and energy consumption in the TelosB platform. Besides proving that some very efficient schemes are actually flawed, we show that the combination of SMQV (strengthened-Menezes-Qu-Vanstone) with implicit certificates leads to a secure and lightweight AKA scheme.

Contemporaneidade e vida privada: olhares interdisciplinares sobre o Brasil

This article discusses the book Contrasts of Contemporary Intimacy. The text analyzes its divisions into periods, territorial criteria, conceptions of sociability, and other features of Historical methods. It points out conquests and limits in this dialogue between Social Sciences and Historical Knowledge.