Individual isotopic specializations predict subsequent inter-individual variation in movement in a freshwater fish.

Despite many similarities and intuitive links between individual dietary specialization and behavioral inter-individual variation, these phenomena have been studied in isolation, and empirical data confirming relationships between these intraspecific variance sources are lacking. Here we use stable isotope analysis and acoustic telemetry to test the hypothesis that individual specialization in trophic (δ15 N) and littoral/pelagic prey reliance (δ13 C) covary with inter-individual variation in movement in a group of 34 free-swimming burbot (Lota lota). By performing stable isotope analysis on tissues with differing isotopic turnover rates (anal fin and dorsal muscle), in 24 lethally sampled burbot, we demonstrate that individual specialization in trophic niche (δ15 N) and littoral/pelagic prey reliance (δ13 C) occurred within the population. By performing stable isotope analysis on anal fins of a group of telemetry tagged burbot, we were able to show that interactions between trophic niche and littoral/pelagic prey reliance, explained a significant proportion of the subsequent between-individual variance in mean movement rates. These findings demonstrate an empirical connection between behavioral inter-individual variation and dietary specialization, thus providing a substantial expansion of our understanding of the wider ecological consequences of these interesting phenomena.

Temporal plasticity in thermal-habitat selection of burbot Lota lota a diel-migrating winter-specialist.

In this study, animal-borne telemetry with temperature sensors was coupled with extensive habitat temperature monitoring in a dimictic reservoir, to test the following hypotheses: behavioural thermoregulation occurs throughout the year and temperature selection varies on a diel and seasonal basis, in a winter-specialist diel-migrating fish. Burbot Lota lota demonstrated nightly behavioural thermoregulation throughout the year, with a large seasonal shift between selection for very cold temperatures (<2° C) optimal for reproduction during the spawning period and selection for warmer temperatures (12-14° C) optimal for hunting and feeding during non-reproductive periods. During daylight hours, while L. lota avoided habitats warmer than optimal for reproduction and feeding during the spawning and non-reproductive periods, respectively, active selection was limited to selection for 4-6° C habitat during the prespawning period. Although behavioural thermoregulation explained the night-time migration, behavioural thermoregulation only partially explained daytime behaviour, indicating that diel migration is best explained by a combination of factors. Thus, thermal-habitat selection was a good predictor of night-time habitat occupancy in a diel-migrating species. Together, these results show that thermal-habitat selection by fishes may be important throughout the year and a more seasonally plastic behaviour than previously recognized.

Comparison of scoring systems and outcome of patients admitted to a liver intensive care unit of a tertiary referral centre with severe variceal bleeding.

BACKGROUND: Acute variceal haemorrhage (AVH) is associated with significant mortality. AIMS: To determine outcome and factors associated with hospital mortality (HM) in patients with AVH admitted to intensive care unit (ICU) and to compare outcomes of patients requiring transfer to a tertiary ICU (transfer group, TG) to a local in-patient group (LG). METHODS: A retrospective study of all adult patients (N = 177) admitted to ICU with AVH from 2000-2008 was performed. RESULTS: Median age was 48 years (16-80). Male represented 58%. Median MELD score was 16 (6-39), SOFA score was 8 (6-11). HM was higher in patients who had severe liver disease or critical illness measured by MELD, SOFA, APACHE II scores and number of failed organs (NFO), P < 0.05. Patients with day-1 lactate ≥ 2 mmol/L had increased HM (P < 0.001). MELD score performed as well as APACHE II, SOFA and NFO (P < 0.001) in predicting HM (AUROC = 0.84, 0.81, 0.79 and 0.82, respectively P > 0.05 for pair wise comparisons). Re-bleeding was associated with increased HM (56.9% vs. 31.6%, P = 0.002). The TG (n = 124) had less severe liver disease and critical illness and consequently had lower HM than local patients (32% vs. 57%, P = 0.002). TG patients with ≥2 endoscopies prior to transfer had increased 6-week mortality (P = 0.03). Time from bleeding to transfer ≥3 days was associated with re-bleeding (OR = 2.290, P = 0.043). CONCLUSIONS: MELD score was comparable to ICU prognostic models in predicting mortality. Blood lactate was also predictive of hospital mortality. Delays in referrals and repeated endoscopy were associated with increased re-bleeding and mortality in this group.

Do steatosis and steatohepatitis impact on sustained virological response (SVR) rates in patients receiving pegylated interferon and ribavirin for chronic hepatitis C infection?

The impact of steatosis on treatment response in chronic hepatitis C infection is controversial. The aim of this study was to determine whether steatosis +/- steatohepatitis on pre-treatment liver biopsy influenced sustained virological response (HCV RNA negative 6 months after completing therapy) in patients with chronic hepatitis C infection treated with pegylated interferon-alpha and ribavirin. One hundred and seventy-nine patients, median age 46 years (interquartile range 40-52), treated between 2001 and 2005. Histological evidence of steatosis was present in 93 patients (52%) and steatohepatitis in 33 patients (18%), 31 patients (17.3%) were cirrhotic. There were 106 (59%) responders, who were similar to non-responders in respect to gender, age, and pre-treatment ALT. On univariate analysis, infection with genotype 2 or 3 was associated with sustained virological response (odds ratio 6.5 (95% CI, 3.3-12.5); P < 0.0001), whereas cirrhosis and patient weight were associated with a reduced response (odds ratios 0.23 (95% CI, 0.11-0.48); P < 0.0001, and 0.97 (95% CI, 0.95-0.99); P < 0.01, respectively); steatohepatitis but not steatosis impacted on the likelihood of achieving sustained virological response (odds ratio 0.37 (95% CI, 0.17-0.77); P = 0.009, and P = 0.18, respectively). Multivariate analysis revealed that infection with genotype 1 or 4 (odds ratio 0.09 (95% CI, 0.03-0.32); P < 0.001) and pre-treatment weight (odds ratio 0.94 (95% CI, 0.90-0.98); P = 0.002) were the only variables associated independently with sustained virological response. In chronic hepatitis C infection, although steatosis was associated with steatohepatitis, neither was shown to affect sustained virological response, which was influenced by genotype, patient weight and the presence of cirrhosis.

Prospective comparison of Fibroscan, King's score and liver biopsy for the assessment of cirrhosis in chronic hepatitis C infection.

Historically, liver biopsy (LB) was the sole method to evaluate the severity of hepatic fibrosis in patients with chronic hepatitis C infection. However, LB is expensive and associated with a risk of severe complications. Therefore, noninvasive tests have been developed to assess the severity of liver fibrosis. The accuracy of Fibroscan (FS) and King's score (KS) was evaluated individually and in combination using liver histology as the reference standard. One hundred and eighty-seven patients were identified who had undergone a biopsy with a diagnosis of chronic hepatitis C virus (HCV) mono-infection (HCV RNA-positive by RT-PCR), attending King's College Hospital (n = 88) or the Royal Free Hospital (n = 99) (London) between May 2006 and December 2007. Liver fibrosis was scored using the Ishak method; significant fibrosis was defined as Ishak fibrosis stage F3-F6, and cirrhosis defined as Ishak fibrosis F5-F6. The diagnostic accuracy of each test was assessed by area under receiver operator characteristic curves (AUROC). Median age was 49 years (43-54) and 115 (61%) were male. The AUROC for FS, KS and FS + KS for the diagnosis of Ishak F3-F6 were 0.83, 0.82 and 0.85, respectively and for the diagnosis of cirrhosis (>or=F5) were 0.96, 0.89 and 0.93, respectively. The negative predictive values for the diagnosis of cirrhosis using the optimal cut-off results for fibrsocan (10.05 kPa), KS (24.3) and the two combined (26.1) were 98%, 91% and 94%, respectively. The noninvasive markers and, particularly, FS were effective tests for the prediction of cirrhosis in chronic hepatitis C. Both KS and FS also had clinical utility for the prediction of Ishak fibrosis stages F3-F6.

A simple, noninvasive test for the diagnosis of liver fibrosis in patients with hepatitis C recurrence after liver transplantation.

Recurrent hepatitis C is a common cause of graft loss in patients undergoing liver transplantation, and serial protocol liver biopsies have been used to identify patients at risk of graft loss from rapid fibrosis progression. The aim of this study was to derive a simple noninvasive index to predict fibrosis in patients with recurrent hepatitis C post-transplant. A retrospective study was performed assessing serial liver biopsies for post-transplant chronic hepatitis C infection. One hundred eighty-five patients were included in the analysis; median age 53 years (interquartile range 48-59) and 140 (76%) were male. Liver histology showed 53 (29%) had Ishak fibrosis stages F0/F1, 31 (17%) had F2, 29 (16%) had F3, 19 (10%) had F4 and 53 (29%) had F5/F6. The London Transplant Centres' (LTC) score was derived combining aspartate aminotransferase (AST IU/L), time from liver transplant (TFLT months), international normalized ratio and platelets. Diagnostic accuracy of the LTC score was assessed using area under receiver-operating characteristic (ROC) curves. The area under the ROC curve for moderate fibrosis (F >or= 2) was 0.78 (95% CI, 0.70-0.86; P < 0.0001), for advanced fibrosis (F4-6) was 0.80 (95% CI, 0.72-0.87; P < 0.0001) and for cirrhosis was 0.80 (95% CI, 0.72-0.88; P < 0.0001). An optimal cut-off value of 6.3 distinguished patients with no or mild fibrosis (F

The impact of hepatic steatosis on the natural history of chronic hepatitis C infection.

Since patients with hepatitis C virus (HCV) often have hepatic steatosis, this retrospective analysis aimed to assess whether steatosis influences fibrosis progression. We studied 112 HCV RNA positive subjects (median age 44, IQR 39-51 years), who had two liver biopsies performed (median biopsy interval 50, 34-74 months). Fibrosis was staged using the Ishak method and steatosis by the Kleiner system (<5% steatosis = S0, 5-33% = S1, 33-66% = S2, and >66% = S3). The subjects were untreated because they had mild fibrosis (n = 59), declined therapy (n = 48), or had co-existing disease precluding treatment (n = 5). On first liver biopsy, 60 (54%) had S0, 34 (30%) had S1, 12 (11%) had S2, and 6 (5%) had S3. Steatosis was associated with genotype 3, odds ratio 4.8 (95% CI 1.3-16.7, P = 0.02). Twenty-three patients (21%) had disease progression on the second biopsy, defined as an increase in Ishak score by > or =1 stage. On univariate analysis, fibrosis progression was associated with older age (P = 0.004), higher AST (P = 0.04), and steatosis (P = 0.005) but on multivariate analysis, only baseline steatosis was significant, odds ratio 14.3 (2.1-111.1, P = 0.006). Kaplan-Meier analysis demonstrated that steatosis impacted on time to progression to both significant fibrosis (Ishak > or =F3) and cirrhosis (Ishak F5-6) (P = 0.001 and P = 0.049, respectively). The finding that steatosis was significantly associated with fibrosis progression indicates that, independent of baseline fibrosis stage, patients should be considered for anti-viral treatment if steatosis is present. Furthermore, strategies to reduce steatosis may have a beneficial effect on fibrosis progression and, therefore, patient outcome.

Current and future management of chronic hepatitis C infection.

Current treatment for patients with chronic hepatitis C virus (HCV) infection consists of the combination of pegylated interferon and ribavirin. This treatment regimen achieves a sustained virological response, defined as undetectable HCV RNA 6 months after treatment cessation, in 50% of patients overall. There is therefore a need for new treatments to improve the sustained virological response rate and reduce the number of adverse effects associated with pegylated interferon and ribavirin. This review examines the current management of chronic HCV infection, including who is eligible for treatment, the optimum duration of treatment, and management of side effects. New drugs in development, such as HCV-specific protease inhibitors, polymerase inhibitors, immune modulators and ribavirin analogues, are outlined, and their role in the treatment armamentarium is discussed, whether used alone or in combination with existing treatments.

Myeloma associated amyloidosis presenting as subacute liver failure.

Multiple myeloma related amyloidosis is rare and its presentation with subacute liver failure (SALF) has not been reported. A case is described of a 46 year old woman presenting with a six week history of nausea, abdominal pain, and jaundice. Routine tests failed to establish a cause. Computed tomography showed a small volume liver consistent with SALF. Emergency liver transplantation was not undertaken because of the suspicion of underlying malignancy. At necropsy, liver biopsy showed amyloid deposition and bone marrow biopsy showed multiple myeloma. Thus, amyloidosis should be added to the list of potential causes of SALF.

Characteristics of autoimmune hepatitis in patients who are not of European Caucasoid ethnic origin.

BACKGROUND: Significant diversity in disease severity has been identified for autoimmune disorders among different ethnic groups but there is a lack of data on autoimmune hepatitis (AIH) in populations other than those of European Caucasoid (EC) or Japanese extraction. AIMS: To assess the clinical features, response to therapy, and eventual outcome in AIH patients of non-EC ethnicity. METHODS: A retrospective review of a regularly updated database of patients with AIH referred to liver outpatient clinics at King's College Hospital, London, since 1983. RESULTS: Twelve patients were identified (10 female; six African, five Asian, one Arabic; median age at presentation 30 years (range 12-58)) who satisfied international criteria for type 1 (11 cases) or type 2 (one case) AIH. Nine (75%) had cholestatic serum biochemistry and three (25%) had mild biliary changes on liver biopsy without definitive features of primary biliary cirrhosis or cholangiographic evidence of primary sclerosing cholangitis. Four showed a complete biochemical response to standard prednisolone with or without azathioprine therapy, three partial, and five no response. Four have required liver transplantation for intractable disease. By comparison with 180 EC patients with definite AIH attending during the same period, the non-EC patients were younger (p<0.05), presented with cholestatic biochemistry (p=0.014), and morphological biliary features more frequently (p<0.0005) and showed a poorer initial response to standard therapy (p<0.0005). CONCLUSIONS: Clinical expression of AIH in non-EC patients seems to differ in important respects from that in EC or Japanese patients. Management of such patients is challenging and may require alternative or more aggressive treatment strategies.

Crystal structure of manganese catalase from Lactobacillus plantarum.

BACKGROUND: Catalases are important antioxidant metalloenzymes that catalyze disproportionation of hydrogen peroxide, forming dioxygen and water. Two families of catalases are known, one having a heme cofactor, and the other, a structurally distinct family containing nonheme manganese. We have solved the structure of the mesophilic manganese catalase from Lactobacillus plantarum and its azide-inhibited complex. RESULTS: The crystal structure of the native enzyme has been solved at 1.8 A resolution by molecular replacement, and the azide complex of the native protein has been solved at 1.4 A resolution. The hexameric structure of the holoenzyme is stabilized by extensive intersubunit contacts, including a beta zipper and a structural calcium ion crosslinking neighboring subunits. Each subunit contains a dimanganese active site, accessed by a single substrate channel lined by charged residues. The manganese ions are linked by a mu1,3-bridging glutamate carboxylate and two mu-bridging solvent oxygens that electronically couple the metal centers. The active site region includes two residues (Arg147 and Glu178) that appear to be unique to the Lactobacillus plantarum catalase. CONCLUSIONS: A comparison of L. plantarum and T. thermophilus catalase structures reveals the existence of two distinct structural classes, differing in monomer design and the organization of their active sites, within the manganese catalase family. These differences have important implications for catalysis and may reflect distinct biological functions for the two enzymes, with the L. plantarum enzyme serving as a catalase, while the T. thermophilus enzyme may function as a catalase/peroxidase.

The high-resolution X-ray crystallographic structure of the ferritin (EcFtnA) of Escherichia coli; comparison with human H ferritin (HuHF) and the structures of the Fe(3+) and Zn(2+) derivatives.

The high-resolution structure of the non-haem ferritin from Escherichia coli (EcFtnA) is presented together with those of its Fe(3+) and Zn(2+) derivatives, this being the first high-resolution X-ray analysis of the iron centres in any ferritin. The binding of both metals is accompanied by small changes in the amino acid ligand positions. Mean Fe(A)(3+)-Fe(B)(3+) and Zn(A)(2+)-Zn(B)(2+) distances are 3.24 A and 3.43 A, respectively. In both derivatives, metal ions at sites A and B are bridged by a glutamate side-chain (Glu50) in a syn-syn conformation. The Fe(3+) derivative alone shows a third metal site (Fe( C)( 3+)) joined to Fe(B)(3+) by a long anti-anti bidentate bridge through Glu130 (mean Fe(B)(3+)-Fe(C)(3+) distance 5.79 A). The third metal site is unique to the non-haem bacterial ferritins. The dinuclear site lies at the inner end of a hydrophobic channel connecting it to the outside surface of the protein shell, which may provide access for dioxygen and possibly for metal ions shielded by water. Models representing the possible binding mode of dioxygen to the dinuclear Fe(3+) pair suggest that a gauche micro-1,2 mode may be preferred stereochemically. Like those of other ferritins, the 24 subunits of EcFtnA are folded as four-helix bundles that assemble into hollow shells and both metals bind at dinuclear centres in the middle of the bundles. The structural similarity of EcFtnA to the human H chain ferritin (HuHF) is remarkable (r.m.s. deviation of main-chain atoms 0.66 A) given the low amino acid sequence identity (22 %). Many of the conserved residues are clustered at the dinuclear centre but there is very little conservation of residues making inter-subunit interactions.

Conformational propagation with prion-like characteristics in a simple model of protein folding.

Protein refolding/misfolding to an alternative form plays an aetiologic role in many diseases in humans, including Alzheimer's disease, the systemic amyloidoses, and the prion diseases. Here we have discovered that such refolding can occur readily for a simple lattice model of proteins in a propagatable manner without designing for any particular alternative native state. The model uses a simple contact energy function for interactions between residues and does not consider the peculiarities of polypeptide geometry. In this model, under conditions where the normal (N) native state is marginally stable or unstable, two chains refold from the N native state to an alternative multimeric energetic minimum comprising a single refolded conformation that can then propagate itself to other protein chains. The only requirement for efficient propagation is that a two-faced mode of packing must be in the ground state as a dimer (a higher-energy state for this packing leads to less efficient propagation). For random sequences, these ground-state dimeric configurations tend to have more beta-sheet-like extended structure than almost any other sort of dimeric ground-state assembly. This implies that propagating states (such as for prions) are beta-sheet rich because the only likely propagating forms are beta-sheet rich. We examine the details of our simulations to see to what extent the observed properties of prion propagation can be predicted by a simple protein folding model. The formation of the alternative state in the present model shows several distinct features of amyloidogenesis and of prion propagation. For example, an analog of the phenomenon of conformationally distinct strains in prions is observed. We find a parallel between 'glassy' behavior in liquids and the formation of a propagatable state in proteins. This is the first report of simulation of conformational propagation using any heteropolymer model. The results imply that some (but not most) small protein sequences must maintain a sequence signal that resists refolding to propagatable alternative native states and that the ability to form such states is not limited to polypeptides (or reliant on regular hydrogen bonding per se) but can occur for other protein-like heteropolymers.

Digging for dead genes: an analysis of the characteristics of the pseudogene population in the Caenorhabditis elegans genome.

Pseudogenes are non-functioning copies of genes in genomic DNA, which may either result from reverse transcription from an mRNA transcript (processed pseudogenes) or from gene duplication and subsequent disablement (non-processed pseudogenes). As pseudogenes are apparently 'dead', they usually have a variety of obvious disablements (e.g., insertions, deletions, frameshifts and truncations) relative to their functioning homologs. We have derived an initial estimate of the size, distribution and characteristics of the pseudogene population in the Caenorhabditis elegans genome, performing a survey in 'molecular archaeology'. Corresponding to the 18 576 annotated proteins in the worm (i.e., in Wormpep18), we have found an estimated total of 2168 pseudogenes, about one for every eight genes. Few of these appear to be processed. Details of our pseudogene assignments are available from http://bioinfo.mbb.yale.edu/genome/worm/pseudogene. The population of pseudogenes differs significantly from that of genes in a number of respects: (i) pseudogenes are distributed unevenly across the genome relative to genes, with a disproportionate number on chromosome IV; (ii) the density of pseudogenes is higher on the arms of the chromosomes; (iii) the amino acid composition of pseudogenes is midway between that of genes and (translations of) random intergenic DNA, with enrichment of Phe, Ile, Leu and Lys, and depletion of Asp, Ala, Glu and Gly relative to the worm proteome; and (iv) the most common protein folds and families differ somewhat between genes and pseudogenes-whereas the most common fold found in the worm proteome is the immunoglobulin fold and the most common 'pseudofold' is the C-type lectin. In addition, the size of a gene family bears little overall relationship to the size of its corresponding pseudogene complement, indicating a highly dynamic genome. There are in fact a number of families associated with large populations of pseudogenes. For example, one family of seven-transmembrane receptors (represented by gene B0334.7) has one pseudogene for every four genes, and another uncharacterized family (represented by gene B0403.1) is approximately two-thirds pseudogenic. Furthermore, over a hundred apparent pseudogenic fragments do not have any obvious homologs in the worm.

Management and outcome of pregnancy in autoimmune hepatitis.

BACKGROUND: There is a paucity of data in the literature on the risks associated with, and optimal management of, pregnancy in patients with autoimmune hepatitis (AIH). AIMS: To assess maternal and fetal outcomes in relation to clinical management of pregnancy in a large cohort of patients with well defined AIH. METHODS: A review of all known pregnancies in 162 females with definite AIH attending our clinics between 1983 and 1998, with respect to treatment, natural history, and outcome. RESULTS: Thirty one live births (one twin) resulted from 35 pregnancies in 18 women (seven with cirrhosis). Median age at conception was 28 years (range 18-36). Two patients presented with AIH de novo during pregnancy. At conception, in 15 pregnancies patients had been receiving azathioprine alone or (in nine) with prednisolone, in seven prednisolone alone, and in one cyclosporin. Fetal loss at > or =20 weeks' gestation occurred in two instances. Flares in disease activity occurred during four pregnancies and within three months of delivery in a further four. Among the 31 children born (median follow up 10 years) only two abnormalities have been identified: Perthes' disease in one and severe mental and physical handicap in a second who was born prematurely following decompensation of the mother's liver disease. Neither mother was receiving azathioprine. CONCLUSIONS: Successful completion of pregnancy is a realistic expectation for patients with well controlled AIH. Treatment options vary, but azathioprine appears to be generally safe and without adverse outcomes for mother or baby. Vigilance is required, however, and patients need to be monitored carefully during pregnancy and for several months post partum.

Regulation of HGF/SF gene expression in MRC-5 cells by N-acetylcysteine.

The effect of N-acetylcysteine (NAC) on levels of hepatocyte growth factor/scatter factor (HGF/SF) gene transcripts was investigated in the human lung embryonic fibroblast cell line, MRC-5. NAC increased expression of HGF/SF mRNA, in a dose- and time-dependent fashion, by a mechanism independent of glutathione synthesis but sensitive to oxidant stress induced by H(2)O(2). Using actinomycin D to block RNA synthesis, it was observed that NAC had no effect on the stability of the HGF/SF mRNA transcripts. NAC increased HGF/SF promoter activity in cells transiently transfected with chloramphenicol acetyltransferase (CAT) reporter genes driven by HGF/SF gene 5'-flanking sequences. Primer extension analysis demonstrated that NAC enhanced the expression of HGF/SF mRNA transcribed from the main transcription initiation site. Although the 5' flanking region of the HGF/SF gene contains a sequence at -1019 to -1011 with homology to the NF-kappaB response element, electrophoretic mobility shift assay demonstrated that this site did not bind nuclear factors in MRC-5 cells in the presence or absence of NAC. In contrast to the effect on HGF/SF mRNA, NAC did not increase HGF/SF protein production by MRC-5 cells.

A prospective, randomized comparison of the ease and safety of variceal ligation using a multiband vs. a conventional ligation device.

BACKGROUND AND STUDY AIMS: Recent advances in endoscopic technology have led to the development of multiple-banding devices which avoid the use of an overtube in endoscopic variceal ligation. In the present study we prospectively examined the safety and efficacy of one such device compared with the conventional single-band ligator. PATIENTS AND METHODS: A total of 45 patients undergoing band ligation were randomly assigned to receive ligation using conventional techniques (n = 22), or multiband ligation (n = 23). RESULTS: The use of the multiband device was associated with a significant reduction in sedation requirements (midazolam 7.1 mg vs. 9.9 mg, P < 0.01, multiband vs. conventional, respectively), less discomfort (4% vs. 23% severe discomfort, P < 0.05). The total time of the endoscopic session was reduced in the multiband group (8 minutes 25 seconds vs. 12 minutes 21 seconds, P < 0.01), as was the time required for application of all the bands (2 minutes 22 seconds vs. 5 minutes 34 seconds, P < 0.001), and average time taken per individual band application (36 seconds vs. 1 minute 36 secs, P < 0.01). In three patients who underwent ligation using the conventional method, the procedure was stopped because of trauma secondary to overtube application. CONCLUSIONS: Multiband ligation is safer, quicker, and associated with less patient discomfort and morbidity when compared with conventional ligation.

Pathogenesis of ascites in cirrhosis and portal hypertension.

Disturbance of the circulatory system frequently occurs in patients with cirrhosis. Cardiac index and plasma volume increase whereas mean arterial blood pressure and systemic vascular resistance decrease. Marked disturbance in vasoconstrictor and natriuretic systems also exist with activation mediators such as plasma renin, plasma noradrenaline, antidiuretic hormone and endothelin. Renal factors contribute to the pathogenesis of ascites formation although the exact mechanisms are yet to be elucidated. Several theories exist in relation to pathogenesis although none to date fully explain all of the findings observed in clinical practice. In this review, we examine the mechanisms that contribute to the development of ascites in patients with cirrhosis and portal hypertension.

Ataxia in prion protein (PrP)-deficient mice is associated with upregulation of the novel PrP-like protein doppel.

The novel locus Prnd is 16 kb downstream of the mouse prion protein (PrP) gene Prnp and encodes a 179 residue PrP-like protein designated doppel (Dpl). Prnd generates major transcripts of 1.7 and 2.7 kb as well as some unusual chimeric transcripts generated by intergenic splicing with Prnp. Like PrP, Dpl mRNA is expressed during embryogenesis but, in contrast to PrP, it is expressed minimally in the CNS. Unexpectedly, Dpl is upregulated in the CNS of two PrP-deficient (Prnp(0/0)) lines of mice, both of which develop late-onset ataxia, suggesting that Dpl may provoke neurodegeneration. Dpl is the first PrP-like protein to be described in mammals, and since Dpl seems to cause neurodegeneration similar to PrP, the linked expression of the Prnp and Prnd genes may play a previously unrecognized role in the pathogenesis of prion diseases or other illnesses.

Prevention of bile duct cancer in primary sclerosing cholangitis.

Patients with primary sclerosing cholangitis (PSC) have a substantial predisposition to develop bile duct carcinoma. The mechanism is still unclear but the observation that patients with chronic Clonorchis sinensis infection are also prone to cholangiocarcinoma suggests a role for long standing inflammation. However, there is still no effective medical therapy which can halt the progression of the disease or prevent the development of cholangiocarcinoma. The only effective treatment for advanced PSC is orthotopic liver transplantation (OLT) which in the absence of cholangiocarcinoma has a 5 year survival of 89%. Patients with cholangiocarcinoma who undergo liver transplantation have a high risk of recurrence and a dramatically worse survival. Therefore, the identification of patients with a sufficient deterioration in liver function to warrant OLT before they develop cholangiocarcinoma remains a central goal in the management of PSC. Ideally, screening patients with PSC would allow the identification of those with dysplastic change in the biliary epithelia before the development of overt carcinoma. However, although serum tumour markers such as CA 19.9 and CEA can be of value in aiding the diagnosis of cholangiocarcinoma in PSC there is currently no evidence that they are helpful in identifying those patients with premalignant changes of the biliary epithelia who would benefit from surgery. There are also no genetic markers to identify those at particular risk of malignant change. A recent report has suggested that regular biliary cytology sampling to detect dysplasia can predict the development of cholangiocarcinoma. However, regular instrumentation of the biliary tree to obtain cytology is unlikely to be widely adopted.