Does Biliodigestive Anastomosis Have Any Effect on the Reversal of Hepatopulmonary Syndrome in a Biliary Cirrhosis Experimental Model?

BACKGROUND: Biliary cirrhosis is associated with hepatopulmonary syndrome (HPS), which is related to increased posttransplant morbidity and mortality. AIMS: This study aims to analyze the pathophysiology of biliary cirrhosis and the onset of HPS. METHODS: Twenty-one-day-old Wistar rats were subjected to common bile duct ligation and were allocated to two groups: group A (killed 2, 3, 4, 5, or 6 weeks after biliary obstruction) and group B (subjected to biliodigestive anastomosis 2, 3, 4, 5, or 6 weeks after the first procedure and killed 3 weeks later). At the killing, arterial blood was collected for the analyses, and samples from the liver and lungs were collected for histologic and molecular analyses. The gasometric parameters as well as the expression levels of ET-1, eNOS, and NOS genes in the lung tissue were evaluated. RESULTS: From a total of 42 blood samples, 15 showed hypoxemia (pO2 < 85 mmHg) and 17 showed an increased oxygen gradient [p (A-a) O2 > 18 mmHg]. The liver histology revealed increased ductular proliferation after common bile duct ligation, and reconstruction of bile flow promoted decreased ductular proliferation 5 and 6 weeks post-common bile duct ligation. Pulmonary alterations consisted of decreased parenchymal airspace and increased medial wall thickness. Biliary desobstruction promoted transitory improvements 5 weeks after biliary obstruction (increased parenchymal airspace and decreased MWT-p = 0.003 and p = 0.004, respectively) as well as increased endothelin expression levels (p = 0.009). CONCLUSIONS: The present model showed lung tissue alterations promoted by biliary obstruction. The biliodigestive anastomosis had no clear direct effects on these alterations.

Does a meso-caval shunt have positive effects in a pig large-for-size liver transplantation model?

In pediatric liver transplantations with LFS grafts, higher incidences of graft dysfunction probably occur due to IRI. It was postulated that increasing the blood supply to the graft by means of a meso-caval shunt could ameliorate the IRI. Eleven pigs underwent liver transplantation and were divided into two groups: LFS and LFS+SHUNT group. A series of flowmetric, metabolic, histologic, and molecular studies were performed. No significant metabolic differences were observed between the groups. One hour after reperfusion, portal flow was significantly lower in the recipients than in the donors, proving that the graft was maintained in low portal blood flow, although the shunt could promote a transient increase in the portal blood flow and a decrease in the arterial flow. Finally, it was verified that the shunt promoted a decrease in inflammation and steatosis scores and a decrease in the expression of the eNOS gene (responsible for the generation of nitric oxide in the vascular endothelium) and an increase in the expression of the proapoptotic gene BAX. The meso-caval shunt was responsible for some positive effects, although other deleterious flowmetric and molecular alterations also occurred.

Does Arterialization of Portal Vein Have Any Effects in Large-for-Size Liver Transplantation? Hemodynamic, Histological, and Biomolecular Experimental Studies.

BACKGROUND: In pediatric liver transplantation, the optimal size of the transplanted liver ranges between 0.8% and 4.0% of the recipient's weight. Sometimes, the graft weight exceeds this upper limit, characterizing the large-for-size condition potentially associated with reduced blood flow and worsening of ischemia-reperfusion injury. Therefore, it would be beneficial to increase the portal flow through arterialization of the portal vein. Materials and methods: Fifteen pigs underwent large-for-size liver transplants. They were divided into two groups: control (CTRL 6 animals - conventional technique) and arterialization - a shunt was established between the portal vein and the splenic artery (ART 9 animals). Hemodynamic, biochemical, histological, and molecular variables were compared. Results: Arterialization resulted in a significant increase in portal vein pressure but no changes in other hemodynamic variables, as shown in the analysis of variance. It was observed lower ALT values (p = 0.007), with no differences regarding the values of blood pH and lactate (p = 0.54 and p = 0.699 respectively) or histological variables (edema, steatosis, inflammation, necrosis, and IRI - p = 1.0, p = 0.943, p = 0.174, p = 0.832, p = 0.662, respectively). The molecular studies showed significantly increased expression of IL6 after 3 hours of reperfusion (p = 0.048) and decreased expression of ICAM immediately after reperfusion (p = 0.03). The regression analysis suggested a positive influence of portal flow and pressure on biochemical parameters. Conclusion: Arterialization of the portal vein showed no histological, biochemical, or molecular benefits in large-for-size transplantation.

Wound healing in weaning, adult, and old rats with provoked incisional hernias. A comparative study.

BACKGROUND: Incisional hernias are more frequent in adults than in children. It is hypothesized that a more efficient healing process in pediatric patients could explain this difference in incidence. Certain elements of healing such as neovascularization, degree of inflammation, percentage of mature and immature collagen, the proliferation of fibroblasts, and expression of certain genes could explain why healing in children is more efficient when compared to the adult and elderly populations. MATERIALS AND METHODS: Seventy-one rats of 3 different age groups (weaning, adult, and old) underwent surgery with 3 different incisions (vertical, oblique, and horizontal). During the procedure, the skin and abdominal wall of the animal were sectioned and only the skin was sutured to mimic incisional hernia in the animals. Four weeks after surgery, the rats were euthanized, their skin was removed, and the extent of scar tissue formed in the muscle opening was measured. In addition, samples of the scar tissue were collected for histological, immunohistochemical, and molecular analyzes. Nine rats served as controls. RESULTS: Shorter-length hernias were formed in weaning rats when compared to old ones when the surgical incision was horizontal (p = 0.03). There was a greater proliferation of fibroblasts in rats in the younger age groups, regardless of the type of incision. The Lox gene was more expressed in weaning rats with vertical and oblique incisions. CONCLUSIONS: These differences could explain the better healing and lower incidence of hernias in the pediatric population, although this aspect requires further studies.

Impact of Three Methods of Ischemic Preconditioning on Ischemia-Reperfusion Injury in a Pig Model of Liver Transplantation.

BACKGROUND: Ischemic preconditioning (IPC), either direct (DIPC) or remote (RIPC), is a procedure aimed at reducing the harmful effects of ischemia-reperfusion (I/R) injury. OBJECTIVES: To assess the local and systemic effects of DIPC, RIPC, and both combined, in the pig liver transplant model. MATERIALS AND METHODS: Twenty-four pigs underwent orthotopic liver transplantation and were divided into 4 groups: control, direct donor preconditioning, indirect preconditioning at the recipient, and direct donor with indirect recipient preconditioning. The recorded parameters were: donor and recipient weight, graft-to-recipient weight ratio (GRWR), surgery time, warm and cold ischemia time, and intraoperative hemodynamic values. Blood samples were collected before native liver removal (BL) and at 0 h, 1 h, 3 h, 6 h, 12 h, 18 h, and 24 h post-reperfusion for the biochemical tests: aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), gamma-glutamyl transferase (GGT), creatinine, BUN (blood urea nitrogen), lactate, total and direct bilirubin. Histopathological examination of liver, gut, kidney, and lung fragments were performed, as well as molecular analyses for expression of the apoptosis-related BAX (pro-apoptotic) and Bcl-XL (anti-apoptotic) genes, eNOS (endothelial nitric oxide synthase) gene, and IL-6 gene related to inflammatory ischemia-reperfusion injury, using real-time polymerase chain reaction (RT-PCR). RESULTS: There were no differences between the groups regarding biochemical and histopathological parameters. We found a reduced ratio between the expression of the BAX gene and Bcl-XL in the livers of animals with IPC versus the control group. CONCLUSIONS: DIPC, RIPC or a combination of both, produce beneficial effects at the molecular level without biochemical or histological changes.

Analysis of the reversibility of biliary cirrhosis in young rats submitted to biliary obstruction.

BACKGROUND/PURPOSE: Biliary atresia and other liver biliary obstructions are relevant conditions in pediatric surgery due to their progression to biliary cirrhosis and indication for liver transplantation. It is known that the period during which biliary obstruction persists determines the development of cirrhosis and its reversibility after a biliary drainage procedure. However, no time or histological markers of biliary cirrhosis reversibility have been established. MATERIALS AND METHODS: One hundred and twenty-nine young Wistar rats underwent surgery for ligation of the common bile duct and were maintained until 8weeks. A part of these animals was submitted to biliary drainage surgery at 2, 3, 4, 5, or 6weeks after the initial procedure. After cyst formation at the site of obstruction, cyst-jejunal anastomosis was performed to restore bile flow. After biliary obstruction and drainage, liver samples were collected for histological and molecular analysis of the genes responsible for collagen deposition and fibrosis. RESULTS: The mortality rates were 39.8% and 56.7% after the first and second procedures, respectively. Ductular proliferation (p=0.001) and collagen deposition increased according to the period under obstruction (p=0.0001), and both alterations were partially reduced after biliary drainage. There were no significant differences in the values of desmin and α-actin according to the period during which the animal remained with biliary obstruction (p=0.09 and p=0.3, respectively), although increased values of transforming growth factor beta 1 (TGFß1) occurred after 8weeks (p=0.000). Desmin levels decreased, and α-actin and TGFß1 levels increased according to the period under obstruction. The molecular alterations were partially reversed after biliary drainage. CONCLUSIONS: The histologic and molecular changes in the liver parenchyma promoted by biliary obstruction in the young animal can be partially reversed by a biliary drainage procedure.

Wound healing in weaning, adult, and old rats with provoked incisional hernias. A comparative study

Abstract Background: Incisional hernias are more frequent in adults than in children. It is hypothesized that a more efficient healing process in pediatric patients could explain this difference in incidence. Certain elements of healing such as neovascularization, degree of inflammation, percentage of mature and immature collagen, the proliferation of fibroblasts, and expression of certain genes could explain why healing in children is more efficient when compared to the adult and elderly populations. Materials and methods: Seventy-one rats of 3 different age groups (weaning, adult, and old) underwent surgery with 3 different incisions (vertical, oblique, and horizontal). During the procedure, the skin and abdominal wall of the animal were sectioned and only the skin was sutured to mimic incisional hernia in the animals. Four weeks after surgery, the rats were euthanized, their skin was removed, and the extent of scar tissue formed in the muscle opening was measured. In addition, samples of the scar tissue were collected for histological, immunohistochemical, and molecular analyzes. Nine rats served as controls. Results: Shorter-length hernias were formed in weaning rats when compared to old ones when the surgical incision was horizontal (p = 0.03). There was a greater proliferation of fibroblasts in rats in the younger age groups, regardless of the type of incision. The Lox gene was more expressed in weaning rats with vertical and oblique incisions. Conclusions: These differences could explain the better healing and lower incidence of hernias in the pediatric population, although this aspect requires further studies.