[Strategies for the prevention of hepatocellular carcinoma in the context of chronic viral hepatitis]. / Strategien zur Prävention des hepatozellulären Karzinoms bei der Hepatitis-Virus-Infektion.

Liver cirrhosis induced by HBV and HCV infections is the main risk factor for the development of hepatocellular carcinoma (HCC). Therefore, prevention of chronic infection with hepatitis viruses and prevention of the development of cirrhosis are essential for the primary prevention of HCC. A consequent vaccination program for HBV is suitable to reduce the rate of infections and the HCC-associated mortality. Since no vaccine is available for HCV, the reduction of risky behaviour and the improvement of hygiene standards are the mainstays for prevention of HCV. An efficient antiviral therapy aimed at the durable suppression of the viral load reduces the risk of progression to cirrhosis and development of HCC in precirrhotic stages of chronic HBV or HCV infections. In cirrhotic patients, the risk of developing HCC remains elevated even if a sustained virological response is achieved, thus requiring further screening with the intention of the early detection of HCC. It is too early to judge whether virological nonresponders profit from continued antiviral therapy. Therefore, the early diagnosis of chronic HBV or HCV infection is the single most important factor for the prevention of HCC. Secondary prevention after surgical resection or local ablative therapy may reduce the frequency of late recurrence. Liver transplantation is today the most effective measure of secondary prevention for selected patients with HCC. Due to its antiproliferative effects, the immunosuppressive drug sirolimus may play a role for secondary prevention of HCC following transplantation.

Association of TLR7 single nucleotide polymorphisms with chronic HCV-infection and response to interferon-a-based therapy.

An efficient immune response against hepatitis C virus (HCV) is necessary to clear infection. As HCV is a single-stranded RNA virus, a role for TLR7 in the immune response against HCV is possible, and early clinical studies have demonstrated an antiviral effect of TLR7 stimulation. We tested the hypothesis that genetic variations of TLR7 are associated with chronic HCV-infection and outcome of therapy. The prevalence of three TLR7 variations was analysed in 978 patients with chronic HCV-infection, 898 patients with chronic liver disease of other aetiologies, and in 203 healthy controls. The prevalence of TLR7 variations was correlated with the response to interferon-alpha-based treatment in 544 patients with chronic HCV-infection. We analysed TLR7 polymorphisms by melting curve analysis and reconstructed haplotypes. The c.32A>T variation was over-represented in female patients with chronic HCV-infection compared to patients with other chronic liver diseases and to healthy controls (P < 0.05). In contrast, c.2403 G>A was less prevalent in male patients with chronic HCV-infection (P < 0.05). No association was observed for the third variant, c.1-120T>G. Haplotype analysis confirmed the differential distribution of TLR7 variants between the groups. Within the group of female patients with chronic HCV-infection, c.32T was predictive of an unfavourable outcome of interferon-alpha therapy (P < 0.05). This study reports the association of TLR7 variants with chronic HCV-infection and with the response to interferon-alpha therapy in patients with chronic HCV-infection. Our results suggest that variations of TLR7 impair the immune response to HCV and imply a gender-specific effect of this X-chromosomal variation.

Percutaneous transjugular direct porto-caval shunt in patients with Budd-Chiari syndrome.

The purpose of the study was to evaluate the feasibility and effectiveness of direct porto-caval shunts in patients with Budd-Chiari syndrome (BCS) in whom there is no access to the hepatic veins during transjugular intrahepatic portosystemic shunt (TIPSS). We included six consecutive patients with fulminant/acute Budd-Chiari syndrome (mean age: 35 years) in whom a conventional TIPSS was not possible due to inaccessible hepatic veins. We performed a direct porto-caval shunt via a transhepatic approach. Patients were followed up by means of clinical examination, laboratory investigations, and Doppler ultrasound. TIPSS implantation from the inferior vena cava (IVC) was successful in all six patients (100%). The median transhepatic shunt length was 9 cm (8-10 cm). No procedure-related complications were observed in our patients. Early shunt occlusion occurred in three out of six patients (50%). In all three of these patients, the stent used to stabilize the shunt ended 1-2 cm before reaching the IVC. All occlusions were successfully recanalized. One of these patients developed recurrent early shunt as well as mesenteric and splenic vein occlusions. She died 7 days after TIPSS placement due to an unmanageable coagulation disorder. The remaining five patients were followed up by planned clinical examination and laboratory investigations (mean follow-up time was 15 months; patient 1 was followed up for 13 months, patient 2 for 14 months, patient 3 for 15 months, and patients 4 and 5 for 16 months) and all displayed a complete and durable resolution of liver failure and ascites without reintervention. In patients with acute liver failure originating from BCS and inaccessible hepatic veins, a direct transhepatic porto-caval shunt can be performed safely and effectively under ultrasound guidance. Future studies in larger patient groups should investigate if the patency of transcaval TIPSS with long transhepatic shunt segments is similar compared to conventional TIPSS via the hepatic vein.

Risk factors for the acquisition of hepatitis C.

About 170 million people are estimated to be chronically infected with hepatitis C worldwide. Despite intense research efforts and considerable improvement of antiviral therapy sustained virological response can only be achieved in a minority of patients due to viral non-response or relapse, contraindications against therapy and high costs. Chronic hepatitis C is the leading cause for end-stage liver disease, hepatocellular carcinoma and liver transplantation in developed countries. To limit the incidence of new infections knowledge about potential transmission pathways and risk factors is crucial. This article aims to summarize recent advances in understanding transmission pathways and outlines future prevention strategies.

Differential mechanisms of neuroprotection by 17 beta-estradiol in apoptotic versus necrotic neurodegeneration.

The major goal of this study was to compare mechanisms of the neuroprotective potential of 17 beta-estradiol in two models for oxidative stress-independent apoptotic neuronal cell death with that in necrotic neuronal cell death in primary neuronal cultures derived from rat hippocampus, septum, or cortex. Neuronal apoptosis was induced either by staurosporine or ethylcholine aziridinium (AF64A), as models for necrotic cell death glutamate exposure or oxygen-glucose deprivation (OGD) were applied. Long-term (20 hr) pretreatment (0.1 microm 17 beta-estradiol) was neuroprotective in apoptotic neuronal cell death induced by AF64A (40 microm) only in hippocampal and septal neuronal cultures and not in cortical cultures. The neuroprotective effect was blocked by the estrogen antagonists ICI 182,780 and tamoxifen and the phosphatidylinositol 3-kinase (PI3-K) inhibitor LY294002. In glutamate and OGD-induced neuronal damage, long-term pretreatment was not effective. In contrast, short-term (1 hr) pretreatment with 17 beta-estradiol in the dose range of 0.5-1.0 microm significantly reduced the release of lactate dehydrogenase and improved morphology of cortical cultures exposed to glutamate or OGD but was not effective in the AF64A model. Staurosporine-induced apoptosis was not prevented by either long- or short-term pretreatment. The strong expression of the estrogen receptor-alpha and the modulation of Bcl proteins by 17 beta-estradiol in hippocampal and septal but not in cortical cultures indicates that the prevention of apoptotic, but not of necrotic, neuronal cell death by 17 beta-estradiol possibly depends on the induction of Bcl proteins and the density of estrogen receptor-alpha.

Serotonin uptake and release mechanisms in developing cultures of rat embryonic raphe neurons: age- and region-specific differences.

The development of serotonergic neurons of the rat raphe was followed in primary neuronal cell cultures taken at embryonic days embryonic day 13 and embryonic day 14 from three different raphe sub-groups, topographically defined with respect to their position to the isthmus as rostral (R1), intermediate (R2) and caudal (R3). In neurons cultivated from embryonic day 13 raphe serotonin, immunoreactivity was detected after only two days in vitro in the rostral R1 and the intermediate R2 sub-groups. Within two weeks of cultivation the number of serotonergic neurons as well as the dendritic branching continuously increased in all three sub-groups. In cultures obtained from embryonic day 13 raphe a specific uptake of [3H]serotonin could not be detected during the first days in vitro. Specific uptake as well as regulated serotonin release, however, was clearly discernible in these cultures after nine days in vitro, indicating developmental differentiation of the initially immature serotonergic neurons in culture. In contrast, serotonergic neurons obtained from the three raphe sub-groups at embryonic day 14 took up and released [3H]serotonin, as early as after two days in culture. Basal as well as stimulated serotonin release was diminished when preincubating the cells with tetanus toxin, which cleaves synaptobrevin thereby blocking exocytosis. Our data indicate that the differential development of serotonergic neurons in the various raphe sub-groups in vivo is also sustained in culture. The differences observed when comparing neurons from embryonic days 13 and 14 suggest that a short time-period of about 24h appears to be crucial for the developmental upregulation of serotonin uptake, storage and release.

Melatonin is protective in necrotic but not in caspase-dependent, free radical-independent apoptotic neuronal cell death in primary neuronal cultures.

To assess the neuroprotective potential of melatonin in apoptotic neuronal cell death, we investigated the efficacy of melatonin in serum-free primary neuronal cultures of rat cortex by using three different models of caspase-dependent apoptotic, excitotoxin-independent neurodegeneration and compared it to that in necrotic neuronal damage. Neuronal apoptosis was induced by either staurosporine or the neurotoxin ethylcholine aziridinium (AF64A) with a delayed occurrence of apoptotic cell death (within 72 h). The apoptotic component of oxygen-glucose deprivation (OGD) unmasked by glutamate antagonists served as a third model. As a model for necrotic cell death, OGD was applied. Neuronal injury was quantified by LDH release and loss of metabolic activity. Although melatonin (0.5 mM) partly protected cortical neurons from OGD-induced necrosis, as measured by a significant reduction in LDH release, it was not effective in all three models of apoptotic cell death. In contrast, exaggeration of neuronal damage by melatonin was observed in native cultures as well as after induction of apoptosis. The present data suggest that the neuroprotectiveness of melatonin strongly depends on the model of neuronal cell death applied. As demonstrated in three different models of neuronal apoptosis, the progression of the apoptotic type of neuronal cell death cannot be withhold or is even exaggerated by melatonin, in contrast to its beneficial effect in the necrotic type of cell death.

Induction of ischemic tolerance in rat cortical neurons by 3-nitropropionic acid: chemical preconditioning.

Sublethal ischemia leads to increased tolerance against subsequent ischemia. We investigated whether tolerance could also be elicited by mild respiratory-chain inhibition (chemical hypoxia) in a rat neuronal-cell enriched culture system. 3-Nitropropionic acid (3-NPA) caused a concentration-dependent inhibition of succinate-dehydrogenase. Two hours preconditioning with 3-NPA 24-48 h before oxygen-glucose deprivation (OGD) reduced neuronal damage morphologically and reduced lactate deydrogenase (LDH) release up to 72% compared to sham-treated sister cultures without 3-NPA. In an attempt to elucidate transcriptional mechanisms, we found no rapid translocation of the hypoxia-sensitive transcription factors N F-KB or hypoxia-inducible factor-I (HIF-I) at 3-NPA concentrations sufficient to trigger tolerance against OGD. In accordance to previous in vivo and brain slice data, we conclude that 3-NPA chemically induces tolerance against oxygen-glucose deprivation in vitro. However, the underlying mechanisms remain elusive.

Attenuated stroke severity after prodromal TIA: a role for ischemic tolerance in the brain?

BACKGROUND AND PURPOSE: Ischemic tolerance has been extensively studied in experimental models of heart and brain ischemia. While there is some clinical evidence of ischemic tolerance in the heart, it is not known whether the same is true for the human brain. METHODS: We conducted a retrospective case-control study in 148 stroke patients with and without antecedent TIA. RESULTS: Despite no significant differences in baseline characteristics, independence (Rankin scale score of 0 to 1) and favorable outcome (Glasgow Coma Scale score of 5) were significantly associated with prior TIA in univariate analysis. After correction for other cardiovascular risk factors, TIA before stroke also was an independent predictor of mild stroke (Canadian Neurological Scale score of > or= 6.5) in multivariate models (absolute difference 21.6%; P=0.01). CONCLUSIONS: Assuming that a TIA represents an adequate stimulus to elicit ischemic tolerance, our results suggest that ischemic tolerance might occur in the human brain.

Induction of tolerance in rat cortical neurons: hypoxic preconditioning.

Sublethal ischemia leads to increased tolerance against subsequent prolonged cerebral ischemia in vivo. In the present study we modeled preconditioning mechanisms in a neuronal-enriched culture. Damage was significantly reduced (up to 72%) with 1.5 h of oxygen-glucose deprivation 48-72 h before 3 h oxygen-glucose deprivation. Tolerance was also elicited by Na+-K+-ATPase inhibition. No damage was observed when astroglial or endothelial cells were exposed to hypoxia for 3 and 6 h, respectively. We conclude that hypoxic preconditioning is a robust neuronal phenomenon in vitro with a similar temporal pattern and selective cellular vulnerability as the ischemic tolerance phenomenon shown in vivo.