Factor VII Transcription Correlates with Hepatocyte Proliferation and Hepatocyte Growth Factor Expression in a Rodent Extrahepatic Portal Vein Obstruction Model

Prostasin and hepatocyte growth factor B in factor VIIa generation: Serine protease knockdowns in zebrafish

BACKGROUND

Blood clotting in humans is initiated by the binding of tissue factor to activated coagulation factor VII (FVIIa) in the plasma. Previous studies have reported that hepsin and factor VII (FVII)-activating protease are responsible for generating FVIIa.

OBJECTIVES

We aimed to identify other proteases that may activate FVII using zebrafish as a model.

METHODS

We screened 179 genes encoding serine protease domains using the piggyback knockdown method to identify genes involved in the activation of zebrafish Fvii. A prolonged kinetic prothrombin time (kPT) assay was used to detect gene knockdown effects.

RESULTS

In the primary screen, 21 genes showed prolonged kPT. In the secondary screen, 14 of 21 genes showed positive results. In the tertiary screen, all 14 genes showed prolonged kPT. These 14 genes were knocked down again to estimate relative levels of zebrafish Fviia. Six genes, including known genes, such as f10 and novel prostasin and hepatocyte growth factor B (hgfb), showed lower Fviia levels. Fvii levels were affected only by the knockdown of f7 and not by the knockdown of the other five genes.

CONCLUSIONS

Prostasin and hgfb are involved in generating Fviia. We hypothesize that prostasin exerts serine protease activity directly or indirectly to activate Fvii. As Hgfb has a mutated serine protease domain, it may not cleave Fvii but may bind to Fvii to induce autoactivation. The approach developed here may be extended to design other large-scale knockdown screens.

Review article: portal vein obstruction--epidemiology, pathogenesis, natural history, prognosis and treatment

BACKGROUND

Portal vein obstruction may be due to portal vein thrombosis (PVT) or its sequale, the portal cavernoma. PVT is a common complication in liver cirrhosis, however, it may also occur as a primary vascular disorder, in absence of any liver disease.

AIM

To review the current knowledge on nomenclature, etiology, pathophysiology, clinical presentation, diagnostic workup and management of adult patients with obstruction in the portal vein, either as a primary vascular disease in adults, or as a complication of liver cirrhosis.

METHODS

A structured search in PubMed was performed using defined keywords (portal vein obstruction, extra-hepatic portal vein obstruction, PVT and portal cavernoma), including full text articles and abstracts in English language.

RESULTS

Several causes, operating both at local and systemic level, might play an important role in the pathogenesis of PVT. Frequently, more than one risk factor could be identified; however, occasionally no single factor is discernible. Diagnosis of portal vein obstruction depends on clinical presentation, imaging and laboratory investigations. Prompt treatment greatly affects the patient's outcome.

CONCLUSIONS

Portal vein obstruction occurring either due to thrombosis in the portal vein or due to the portal cavernoma, can contribute to significant morbidity and mortality in patients with or without cirrhosis. In recent years our understanding of etio-pathogenesis of portal vein obstruction has evolved tremendously, which has led to significant improvement in treatment outcomes. There are still areas where more studies are needed to better clarify the management issues of portal vein obstruction.

Congenital portosystemic vascular malformations

Congenital portosystemic shunts are developmental abnormalities of the portal venous system resulting in the diversion of portal blood away from the liver to the systemic venous system. Such malformations are believed to come from an insult occurring between the fourth and eighth week of gestation during the development of hepatic and systemic venous systems, and could explain their frequent association with cardiac and other vascular anomalies. They are currently categorized into end-to-side shunts (type I) or side-to-side shunts (type II). This article aims to review the common symptoms and complications encountered in congenital portosystemic shunts, the surgical and endovascular treatment, and the role of liver transplantation in this disease. We will also focus on the current controversies and the areas where there is potential for future studies.

Growth impairment in children with extrahepatic portal vein obstruction is improved by mesenterico-left portal vein bypass

BACKGROUND

Extrahepatic portal vein obstruction (EHPVO) has been associated with growth impairment in children. We hypothesized that growth parameters improve after reversal of portal hypertension and restoration of mesenteric venous blood flow to the liver by the mesenterico-left portal vein bypass (MLPVB).

METHODS

A retrospective review of 45 children with idiopathic EHPVO who underwent MLPVB between 1997 and 2007 and had follow-up data for analysis was carried out. Growth was assessed using SD scores (z scores) for height, weight, and body mass index (BMI) at the time of operation and at early (5-12 months) and late (13-24 months) follow-up.

RESULTS

The mean height and weight of children with EHPVO was significantly lower than the general population before surgery. Mean BMI was also lower, although statistically insignificant. All parameters increased significantly after MLPVB as follows: height from -0.42 before surgery to -0.12 (P = .027) at 5 to 12 months and -0.14 (P = .026) at 13 to 24 months; weight from -0.49 before surgery to 0.03 (P < .001) at 5 to 12 months and 0.35 (P < .001) at 13 to 24 months; and BMI from -0.22 before surgery to 0.17 (P = .001) at 5 to 12 months and 0.48 (P < .001) at 13 to 24 months.

CONCLUSION

Restoration of portal blood flow to the liver by MLPVB improves growth in children with EHPVO.