Treatment responses in Asians and Caucasians with chronic hepatitis C infection

AIM：To conduct a multicentre retrospective review of virological response rates in Asians infected with genotype 1 chronic hepatitis C（CHC） treated with combination interferon and ribavirin and then to compare their responses to that among Caucasians.
METHODS：Asian patients infected with genotype 1 CHC treated at 4 Australian centres between 2001 to 2005 were identified through hospital databases.Baseline demographic characteristics,biochemical,virological and histological data and details of treatment were collected.Sustained virological responses（SVR） in this cohort were then compared to that in Caucasian subjects,matched by genotype,age,gender and the stage of hepatic fibrosis.
RESULTS：A total of 108 Asians with genotype 1 CHC were identified.The end of treatment response（ETR） for the cohort was 79% while the SVR was 67%.Due to the relatively advanced age of the Asian cohort,only sixty-four subjects could be matched with Caucasians.The ETR among matched Asians and Caucasians was 81% and 56% respectively（P=0.003）,while the SVR rates were 73% and 36%（P 〈0.001） respectively.This difference remained significant after adjusting for other predictive variables.
CONCLUSION： Genotype 1 CHC in Asian subjects is associated with higher rates of virological response compared to that in Caucasians.     

Surveillance of Artemisinin Resistance in Plasmodium falciparum in India Using the kelch13 Molecular Marker

Malaria treatment in Southeast Asia is threatened with the emergence of artemisinin-resistant Plasmodium falciparum. Genome association studies have strongly linked a locus on P. falciparum chromosome 13 to artemisinin resistance, and recently, mutations in the kelch13 propeller region (Pfk-13) were strongly linked to resistance. To date, this information has not been shown in Indian samples. Pfk-13 mutations were assessed in samples from efficacy studies of artemisinin combination treatments in India. Samples were PCR amplified and sequenced from codon 427 to 727. Out of 384 samples, nonsynonymous mutations in the propeller region were found in four patients from the northeastern states, but their presence did not correlate with ACT treatment failures. This is the first report of Pfk-13 point mutations from India. Further phenotyping and genotyping studies are required to assess the status of artemisinin resistance in this region.     

Mutations disrupting the Kennedy phosphatidylcholine pathway in humans with congenital lipodystrophy and fatty liver disease

Phosphatidylcholine (PC) is the major glycerophospholipid in eukaryotic cells and is an essential component in all cellular membranes. The biochemistry of de novo PC synthesis by the Kennedy pathway is well established, but less is known about the physiological functions of PC. We identified two unrelated patients with defects in the Kennedy pathway due to biallellic loss-of-function mutations in phosphate cytidylyltransferase 1 alpha (PCYT1A), the rate-limiting enzyme in this pathway. The mutations lead to a marked reduction in PCYT1A expression and PC synthesis. The phenotypic consequences include some features, such as severe fatty liver and low HDL cholesterol levels, that are predicted by the results of previously reported liver-specific deletion of murine Pcyt1a. Both patients also had lipodystrophy, severe insulin resistance, and diabetes, providing evidence for an additional and essential role for PCYT1A-generated PC in the normal function of white adipose tissue and insulin action.All living cells are surrounded by a lipid membrane. Eukaryotic cells also contain several internal membrane-bound organelles, which enable them to compartmentalize related biological functions and thereby to enhance the efficiency of these processes. Phospholipids are the predominant component of these membranes. Their hydrophilic head groups interact with the cytosol, whereas their hydrophobic side chains are either buried within the hydrophobic interior of a typical membrane bilayer or interact with the hydrophobic neutral lipid core of lipoproteins and lipid droplets (LDs). Phospholipids are generally defined by their organic head group with phosphatidylcholine (PC) constituting over 50% of all membrane phospholipids. PC was first isolated in the 19th century and the major enzymatic pathway involved in its synthesis was revealed by Kennedy and Weiss (1) in the 1950s. Cells synthesize PC in three consecutive steps (Fig. 1A): choline kinase phosphorylates choline before choline phosphate cytidylyltransferase 1 α (encoded by the PCYT1A gene) generates the high-energy donor CDP-choline in the rate-limiting step of the pathway. In the last step, DAG:CDP-choline cholinephosphotransferase (CPT) uses CDP-choline and diacylglycerol (DAG) to form PC (2, 3).Open in a separate windowFig. 1.Cosegregation of biallelic PCYT1A mutations with fatty liver, low HDL cholesterol levels, lipodystrophy, insulin-resistant diabetes, and short stature. (A) Schematic illustration of the Kennedy PC synthesis pathway. CK, choline kinase; CPT, CDP-choline:1,2-diacylglycerol cholinephosphotransferase; PCYT1A, choline-phosphate cytidylyltransferase A, CTP:phosphocholine-cytidylyltransferase. (B) Family pedigrees of both probands demonstrating that only compound heterozygous carriers of PCYT1A mutations manifest fatty liver (red), low HDL cholesterol (blue), lipodystrophy (yellow), and insulin resistance/type 2 diabetes (T2DM) (green). PCYT1A mutation status, height (Ht.), and body mass index (BMI) are indicated below each individual’s symbol. ND, not determined; WT, wild type. (C) The location of PCYT1A mutations E280del, V142M, and 333fs in relation to known functional domains of PCYT1A. Domain M, membrane binding domain; domain P, phosphorylated region. (D) Conservation around the V142(red*) and E280(red*) mutation sites. Sequence alignment of representative metazoan sequences in the region surrounding the mutated residues. Hydrophobic (blue) and polar (green) residues interacting with V142 are highlighted. Only residues different from the human sequence are shown. Sequence IDs: human (Homo sapiens) {"type":"entrez-protein","attrs":{"text":"P49585","term_id":"166214967"}}P49585, zebrafish (Danio rerio) F1QEN6, sea squirt (Ciona intestinalis) {"type":"entrez-protein","attrs":{"text":"XP_002130773.1","term_id":"198437270"}}XP_002130773.1, sea urchin (Strongylocentrotus purpuratus) H3I3V9, water flee (Daphnia pulex) E9G1P5, Drosophila (D. melanogaster) Q9W0D9, Caenorhabditis (C. elegans) {"type":"entrez-protein","attrs":{"text":"P49583","term_id":"32172439"}}P49583, Trichoplax (T. adherens) B3RI62. (E and F) Structure of the catalytic domain of PCYT1A highlighting the role of V142M in the core packing. The two chains in the dimer are shown in yellow and gray; the residues and the secondary structure units are highlighted in color in the yellow monomer A: loop L3 with V142, red; α-helix, green; and the interacting β-sheet, blue. The residues packing with V142 are shown in ball-and-stick and space-filling representations, the dimer stabilizing R140 is shown in ball-and-stick colored according to the atom type. E is a global view, and F is a zoomed-in view of the catalytic core.Membrane phospholipids are a defining feature of advanced life-forms so it is perhaps not surprising that the pathways involved in their synthesis are ancient, and mutations affecting them are rarely tolerated in evolution. Here, we describe the identification and characterization of pathogenic human loss-of-function mutations affecting the eponymous Kennedy pathway.     

Spry1 as a novel regulator of erythropoiesis, EPO/EPOR target, and suppressor of JAK2

Sprouty proteins are established modifiers of receptor tyrosine kinase (RTK) signaling and play important roles in vasculogenesis, bone morphogenesis, and renal uteric branching. Little is understood, however, concerning possible roles for these molecular adaptors during hematopoiesis. Within erythroid lineage, Spry1 was observed to be selectively and highly expressed at CFU-e to erythroblast stages. In analyses of possible functional roles, an Mx1-Cre approach was applied to conditionally delete Spry1. At steady state, Spry1 deletion selectively perturbed erythroid development and led to reticulocytosis plus heightened splenic erythropoiesis. When challenged by hemolysis, Spry1-null mice exhibited worsened anemia and delayed recovery. During short-term marrow transplantation, Spry1-null donor marrow also failed to efficiently rescue the erythron. In each anemia model, however, hyperexpansion of erythroid progenitors was observed. Spry function depends on phosphorylation of a conserved N-terminal PY motif. Through an LC-MS/MS approach, Spry1 was discovered to be regulated via the erythropoietin receptor (EPOR), with marked EPO-induced Spry1-PY53 phosphorylation observed. When EPOR signaling pathways were analyzed within Spry1-deficient erythroid progenitors, hyperactivation of not only Erk1,2 but also Jak2 was observed. Studies implicate Spry1 as a novel regulator of erythropoiesis during anemia, transducer of EPOR signals, and candidate suppressor of Jak2 activity.     

Prospective study of histomorphometry,biochemical bone markers and bone densitometric response to pamidronate in β-thalassaemia presenting with osteopenia-osteoporosis syndrome

This study aimed to evaluate bone remodelling disorders in thalassaemia by using pamidronate (PD) infusion with or without hormone replacement therapy (HRT) as a diagnostic-therapeutic tool. In this prospective study, 24 adult thalassaemia major (TM) and 10 thalassaemia intermedia (TI) patients received either PD and HRT or HRT only (controls) for 3 years. Eugonadal patients with TI had PD only. Bone remodelling was assessed by dual energy X ray absorptiometry (DXA scan), type 1-collagen biochemical bone markers (BBM) and histomorphometry of iliac crest biopsy before and after PD. As a group, thalassaemics had a significant improvement in spinal and femoral bone mineral density Z scores following PD (P < 0·01) compared to the controls. Although BBM were comparable pre-therapy, they were significantly lower in the PD cohort (P < 0·001) compared to the control group. All patients had osteopenia, diminished osteoid formation and bone volume on histomorphometry pre-therapy with high turnover bone disease (HTO) in TM and low-turnover disease (LTO) in TI. In TM, bone volume improved significantly, whereas TI patients showed little or no response to PD. In conclusion, histomorphometry data suggest that TM patients have a distinct pathology of high turnover bone disease compared to TI patients, who have low-turnover disease.     

Screening and Management of Hepatocellular Carcinoma: The Australian Perspective

Hepatocellular cancer (HCC) remains relatively uncommon in Australia, however incidence rates have been progressively rising, as in many other western countries, over the last few decades. Currently, chronic hepatitis B (HBV) or hepatitis C (HCV) infections accounts for the majority of primary liver cancers, but as the incidence of HBV declines with the implementation of immunization programs and HCV is eradicated by direct acting anti viral therapies, more cases will be due to metabolic causes such as non-alcoholic fatty liver disease. The cornerstone of management involves identifying potential risk factors and implementing both preventative and therapeutic strategies. As we gain more knowledge about the pathogenesis of HCC, newer agents such as multikinase inhibtors have been developed to target specific pathways and have been shown to delay time to disease progression. Well defined screening, diagnostic and management algorithms will allow for standardisation of protocols and enable classification of patients and treatment modalities offering some prediction of outcome and prognosis. It is anticipated that effective screening and surveillance programs will enable the detection of tumours at an early stage thereby allowing for a wider range of therapeutic options with improved outcomes.     

Assessment of Hemodialysis Adequacy by Ionic Dialysance: Comparison to Standard Method of Urea Removal

Background. The hemodialysis adequacy is one of the most important issues influencing the survival of patients on maintenance hemodialysis (HD). Assessment of measuring the delivered dialysis dose using clearance × time/volume (Kt/V) index requires multiple blood sampling. New methods for assessment of dialysis dose based on ionic dialysance (ID) have been suggested. Online conductivity monitoring (using sodium flux as a surrogate for urea) allows the repeated noninvasive measurement of Kt/V on each HD treatment. In this study we have compared this method with the standard method of estimating Kt/V. Methods. We studied 24 established HD patients over a 4 week time period. Patients were dialyzed using Fresenius 4008S dialysis monitors, equipped with modules to measure ID. Data were manually collected and analyzed using the appropriate statistical software. Urea removal (UR) was measured once a week by a two-pool calculation, estimating an eKt/V. Results. The Kt/V measured by ID highly correlated with the one derived from the measurement of the UR (r = 0.8959, p< 0.0001). The ID underestimated UR by the mean of 6%. The ID varied greatly within individual patients with a median of 1.29 ± 0.22. If the eKt/V ≥ 1.2 is considered adequate, 33% of the patients would have been inadequately dialyzed. The mean HD duration to achieve an adequate dialysis was 4 hours and 47 minutes with high interpatient variability. Conclusion. The ID seems to be an easily obtained measure of the delivered dialysis dose, correlating well with standard UR method. Substantial individual variations imply that repeated measures (ideally for all treatments) are necessary to obtain a real answer to the mean treatment dose being delivered to the patients.