Decision-making for non-invasive prenatal testing for Down syndrome: Hong Kong Chinese women's preferences for individual vs relational autonomy.

Individual autonomy in antenatal screening is internationally recognized and supported. Policy and practice guidelines in various countries place emphasis on the woman's right to make her own decision and are related to concepts such as self-determination, independence, and self-sufficiency. In contrast, the dominant perspective in Chinese medical ethics suggests that the family is pivotal in making medical decisions, hence providing support for relational autonomy. This study explored Hong Kong Chinese pregnant women's preferences for individual vs relational autonomy for non-invasive prenatal testing (NIPT) for Down syndrome. A qualitative study was carried out using semi-structured interviews with 36 women who had undertaken NIPT in Hong Kong. The findings show that most Hong Kong Chinese women valued aspects of both relational and individual autonomy in decision-making for NIPT. Women expected support from doctors as experts on the topic and wanted to involve their husband in decision-making while retaining control over the outcome. Somewhat surprisingly, the findings do not provide support for the involvement of family members in decision-making for NIPT. The adequacy of current interpretations of autonomy in prenatal testing policies as an individual approach needs discussion, where policy developers need to find a balance between individual and relational approaches.

An updated Asia Pacific Consensus Recommendations on colorectal cancer screening.

OBJECTIVE: Since the publication of the first Asia Pacific Consensus on Colorectal Cancer (CRC) in 2008, there are substantial advancements in the science and experience of implementing CRC screening. The Asia Pacific Working Group aimed to provide an updated set of consensus recommendations. DESIGN: Members from 14 Asian regions gathered to seek consensus using other national and international guidelines, and recent relevant literature published from 2008 to 2013. A modified Delphi process was adopted to develop the statements. RESULTS: Age range for CRC screening is defined as 50-75 years. Advancing age, male, family history of CRC, smoking and obesity are confirmed risk factors for CRC and advanced neoplasia. A risk-stratified scoring system is recommended for selecting high-risk patients for colonoscopy. Quantitative faecal immunochemical test (FIT) instead of guaiac-based faecal occult blood test (gFOBT) is preferred for average-risk subjects. Ancillary methods in colonoscopy, with the exception of chromoendoscopy, have not proven to be superior to high-definition white light endoscopy in identifying adenoma. Quality of colonoscopy should be upheld and quality assurance programme should be in place to audit every aspects of CRC screening. Serrated adenoma is recognised as a risk for interval cancer. There is no consensus on the recruitment of trained endoscopy nurses for CRC screening. CONCLUSIONS: Based on recent data on CRC screening, an updated list of recommendations on CRC screening is prepared. These consensus statements will further enhance the implementation of CRC screening in the Asia Pacific region.

Multidisciplinary management strategies for acute non-variceal upper gastrointestinal bleeding.

BACKGROUND: The modern management of acute non-variceal upper gastrointestinal bleeding is centred on endoscopy, with recourse to interventional radiology and surgery in refractory cases. The appropriate use of intervention to optimize outcomes is reviewed. METHODS: A literature search was undertaken of PubMed and the Cochrane Central Register of Controlled Trials between January 1990 and April 2013 using validated search terms (with restrictions) relevant to upper gastrointestinal bleeding. RESULTS: Appropriate and adequate resuscitation, and risk stratification using validated scores should be initiated at diagnosis. Coagulopathy should be corrected along with blood transfusions, aiming for an international normalized ratio of less than 2·5 to proceed with possible endoscopic haemostasis and a haemoglobin level of 70 g/l (excluding patients with severe bleeding or ischaemia). Prokinetics and proton pump inhibitors (PPIs) can be administered while awaiting endoscopy, although they do not affect rebleeding, surgery or mortality rates. Endoscopic haemostasis using thermal or mechanical therapies alone or in combination with injection should be used in all patients with high-risk stigmata (Forrest I-IIb) within 24 h of presentation (possibly within 12 h if there is severe bleeding), followed by a 72-h intravenous infusion of PPI that has been shown to decrease further rebleeding, surgery and mortality. A second attempt at endoscopic haemostasis is generally made in patients with rebleeding. Uncontrolled bleeding should be treated with targeted or empirical transcatheter arterial embolization. Surgical intervention is required in the event of failure of endoscopic and radiological measures. Secondary PPI prophylaxis when indicated and Helicobacter pylori eradication are necessary to decrease recurrent bleeding, keeping in mind the increased false-negative testing rates in the setting of acute bleeding. CONCLUSION: An evidence-based approach with multidisciplinary collaboration is required to optimize outcomes of patients presenting with acute non-variceal upper gastrointestinal bleeding.

Early clinical experience of the safety and effectiveness of Hemospray in achieving hemostasis in patients with acute peptic ulcer bleeding.

BACKGROUND AND STUDY AIMS: Endoscopic therapy of upper gastrointestinal bleeding remains challenging with conventional endoscopic devices. Use of Hemospray, where a nanopowder with clotting abilities is sprayed onto the bleeding site, had been highly effective for management of arterial bleeding in a heparizined animal model. The safety and effectiveness of Hemospray for hemostasis of active peptic ulcer bleeding in humans was evaluated. PATIENTS AND METHODS: In a prospective, single-arm, pilot clinical study, consecutive adults with confirmed peptic ulcer bleeding (Forrest score Ia or Ib), who had all given informed consent to participation, underwent upper gastrointestinal endoscopy and application of Hemospray within 24 hours of hospital admission once hemodynamically stable. Up to two applications of Hemospray, not exceeding a total of 150 g were allowed. Bleeding recurrence was monitored post procedurally, by second-look endoscopy (72 hours post treatment), and by phone at 30 days. Rate of hemostasis, recurrent bleeding, mortality, need for surgical intervention, and treatment-related complications were assessed. RESULTS: 20 patients were recruited (18 men, 2 women; mean age 60.2 years). Acute hemostasis was achieved in 95 % (19 / 20) of patients; 1 patient had a pseudoaneurysm requiring arterial embolization. Bleeding recurred in 2 patients within 72 hours (shown by hemoglobin drop); neither had active bleeding identified at the 72-hour endoscopy. No mortality, major adverse events, or treatment- or procedure-related serious adverse events were reported during 30-day follow-up. CONCLUSION: These pilot results indicate that Hemospray is safe in humans. Hemospray was effective in achieving acute hemostasis in active peptic ulcer bleeding.

The broad-spectrum antiviral ribonucleoside ribavirin is an RNA virus mutagen.

The ribonucleoside analog ribavirin (1-beta-D-ribofuranosyl-1,2, 4-triazole-3-carboxamide) shows antiviral activity against a variety of RNA viruses and is used in combination with interferon-alpha to treat hepatitis C virus infection. Here we show in vitro use of ribavirin triphosphate by a model viral RNA polymerase, poliovirus 3Dpol. Ribavirin incorporation is mutagenic, as it templates incorporation of cytidine and uridine with equal efficiency. Ribavirin reduces infectious poliovirus production to as little as 0. 00001% in cell culture. The antiviral activity of ribavirin correlates directly with its mutagenic activity. These data indicate that ribavirin forces the virus into 'error catastrophe'. Thus, mutagenic ribonucleosides may represent an important class of anti-RNA virus agents.

Associations between biased threat interpretations, fear and avoidance of pain and pain-linked disability in adolescent chronic pain patients.

BACKGROUND: Biased interpretations of ambiguous bodily threat situations characterize youth with chronic pain, and have been associated with functional disability for this population. Despite predictions by the fear-avoidance model of chronic pain, that fear and avoidance of pain explain the association between threat perceptions and disability, this has not yet been explored in youth with chronic pain. This study aimed to address this gap by investigating these proposed relationships, in addition to the association between bodily threat interpretations and daily aspects of disability (as well as social, and emotional impairments). METHOD: Sixty-eight adolescents aged 11-18 years old with a clinical diagnosis of chronic pain completed an extended version of the Adolescent Interpretations of Bodily Threat task to assess interpretations of bodily and social threat situations, alongside measures of disability and fear and avoidance of pain. RESULTS: Using mediation analysis, fear and avoidance of pain statistically accounted for the relationship between negative bodily threat interpretations and functional disability. Significant associations were also demonstrated between negative bodily threat interpretations and adolescent-reported impairments in daily, emotional and social impairments. Data revealed a significant relationship between negative social interpretations and daily functional disability. CONCLUSIONS: Findings indicate the clinical relevance of bodily and social threat interpretations, and fear and avoidance of pain, for this population and raise further questions regarding the content-specificity of threat interpretations. SIGNIFICANCE: Psychological theories of pain-associated impact and disability point to fear and avoidance of pain, as well as information-processing biases. Here, we present novel data showing the clinical relevance of bodily and social threat interpretations in explaining pain-related disability amongst youth with chronic pain, potentially by shaping fear and avoidance of pain. Longitudinal designs will be required to assess these temporally sensitive mediation pathways.

Natural interferon alpha/beta-producing cells link innate and adaptive immunity.

Innate immune responses to pathogens critically impact the development of adaptive immune responses. However, it is not completely understood how innate immunity controls the initiation of adaptive immunities or how it determines which type of adaptive immunity will be induced to eliminate a given pathogen. Here we show that viral stimulation not only triggers natural interferon (IFN)-alpha/beta-producing cells (IPCs) to produce vast amounts of antiviral IFN-alpha/beta but also induces these cells to differentiate into dendritic cells (DCs). IFN-alpha/beta and tumor necrosis factor alpha produced by virus-activated IPCs act as autocrine survival and DC differentiation factors, respectively. The virus-induced DCs stimulate naive CD4(+) T cells to produce IFN-gamma and interleukin (IL)-10, in contrast to IL-3-induced DCs, which stimulate naive CD4(+) T cells to produce T helper type 2 cytokines IL-4, IL-5, and IL-10. Thus, IPCs may play two master roles in antiviral immune responses: directly inhibiting viral replication by producing large amounts of IFN-alpha/beta, and subsequently triggering adaptive T cell-mediated immunity by differentiating into DCs. IPCs constitute a critical link between innate and adaptive immunity.

Precut sphincterotomy using insulated angulotome.

A newly designed insulated angulotome was evaluated in a series of patients in whom biliary cannulation using conventional methods had failed and who required precut sphincterotomy. The new device consists of an insulated glass tip to prevent excessive electrocautery flow, and angulation to facilitate elevation of the papillary roof on cutting. A prospective series of patients with cholangitis or obstructive jaundice with failed biliary cannulation were recruited. The success of cannulation and complications following endoscopic retrograde cholangiopancreatography were analyzed. A total of 13 patients underwent precut sphincterotomy using the insulated angulotome. The immediate success of gaining biliary access after failed cannulation was 100 %. The mean size of the common bile duct on ultrasonography was 8.1 mm. The mean time to achieve biliary cannulation was 9 minutes 4 seconds, and there was no perforation or bleeding. This case series showed that precut sphincterotomy with the insulated angulotome can be safely performed without major complications.

Asia Pacific consensus recommendations for colorectal cancer screening.

Colorectal cancer (CRC) is rapidly increasing in Asia, but screening guidelines are lacking. Through reviewing the literature and regional data, and using the modified Delphi process, the Asia Pacific Working Group on Colorectal Cancer and international experts launch consensus recommendations aiming to improve the awareness of healthcare providers of the changing epidemiology and screening tests available. The incidence, anatomical distribution and mortality of CRC among Asian populations are not different compared with Western countries. There is a trend of proximal migration of colonic polyps. Flat or depressed lesions are not uncommon. Screening for CRC should be started at the age of 50 years. Male gender, smoking, obesity and family history are risk factors for colorectal neoplasia. Faecal occult blood test (FOBT, guaiac-based and immunochemical tests), flexible sigmoidoscopy and colonoscopy are recommended for CRC screening. Double-contrast barium enema and CT colonography are not preferred. In resource-limited countries, FOBT is the first choice for CRC screening. Polyps 5-9 mm in diameter should be removed endoscopically and, following a negative colonoscopy, a repeat examination should be performed in 10 years. Screening for CRC should be a national health priority in most Asian countries. Studies on barriers to CRC screening, education for the public and engagement of primary care physicians should be undertaken. There is no consensus on whether nurses should be trained to perform endoscopic procedures for screening of colorectal neoplasia.

Endoscopic submucosal dissection used for treating early neoplasia of the foregut using a combination of knives.

BACKGROUND: Endoscopic submucosal dissection (ESD) has emerged as a novel technique for achieving en bloc resection for early esophageal or gastric carcinoma limited to the mucosa. The authors report their experience with a combination of various devices to treat early neoplasia of the foregut using the ESD technique. METHODS: In this prospective case series, ESD was performed for early esophageal or gastric carcinoma limited to the mucosa. These lesions were staged by endoscopic ultrasonography before resection. Magnifying endoscopy and chromoendoscopy were used to locate the tumor and define the margin. The resection was accomplished with submucosal dissection using the insulated tip knife, the hook knife, and the triangular tip knife. The resected specimen was examined systematically for the lateral and deep margins. RESULTS: From January 2004 to March 2006, ESD was performed to manage 30 cases of early gastric or esophageal carcinoma. For 29 of these patients, R0 resection was successfully achieved. The mean operating time was 84.6 min. One patient experienced reactionary hemorrhage 12 h after resection, which was controlled endoscopically. There was no perforation. Most of the circumferential mucosal incisions were performed using the insulated tip knife (76.6%), whereas submucosal dissection was accomplished with a combination of various knives. One of the specimens showed involvement of the lateral margin, whereas another patient had two areas of new early gastric cancer 6 months after the initial procedure. These patients received salvage laparoscopically assisted gastrectomy. CONCLUSIONS: Endoscopic submucosal dissection to manage early neoplasia of the foregut can be achieved safely and effectively with a combination of knives.

Review article: Asia-Pacific consensus recommendations on endoscopic tissue acquisition for biliary strictures.

BACKGROUND: Pre-operative tissue diagnosis for suspected malignant biliary strictures remains challenging. AIM: To develop evidence-based consensus statements on endoscopic tissue acquisition for biliary strictures. METHODS: The initial draft of statements was prepared following a systematic literature review. A committee of 20 experts from Asia-Pacific region then reviewed, discussed, and modified the statements. Two rounds of independent voting were conducted to reach a final version. Consensus was considered to be achieved when 80% or more of voting members voted "agree completely" or "agree with some reservation." RESULTS: Eleven statements achieved consensus. The choice of tissue sampling modalities for biliary strictures depends on the clinical setting, the location of lesion, and availability of expertise. Detailed radiological and endoscopic evaluation is useful to guide the selection of appropriate tissue acquisition technique. Standard intraductal biliary brushing and/or forceps biopsy is the first option when endoscopic biliary drainage is required with an overall (range) sensitivity and specificity of 45% (26%-72%) and 99% (98%-100%), and 48% (15%-100%) and 99% (97%-100%), respectively, in diagnosing malignant biliary strictures. Probe-based confocal laser endomicroscopy and fluorescence in situ hybridisation using 4 fluorescent-labelled probes targeting chromosomes 3, 7, 17 and 9p21 locus may be added to improve the diagnostic yield. Cholangioscopy-guided biopsy and EUS-guided tissue acquisition can be considered after prior negative conventional tissue sampling with an overall (range) sensitivity and specificity of 60% (38%-88%) and 98% (83%-100%), and 80% (46%-100%) and 97% (92%-100%), respectively, in diagnosing malignant biliary strictures. CONCLUSION: These consensus statements provide evidence-based recommendations for endoscopic tissue acquisition of biliary strictures.

Stressed polystyrene causes increased membrane sensitivity of adherent cells to fluid shear force: technical note.

Adherent cells transduce signals from the extracellular matrix, which result in changes to various cell functions, including cell spreading and morphology. However, changes to mechanical properties of cell membranes due to adherence to a substratum have not been studied. Adherent Nara Bladder Tumour (NBT) II cells on polystyrene (PS) discs made from pure, atactic polystyrene react differently between the peripheral 1mm zone and centre of the disc. After application of a fluid shear force, cells on the peripheral zone resulted in 91.1-/+0.8% cell death due to instantaneous rupture of apical cell membrane, as determined by the Live/Dead cell assay, whereas cells on the disc's centre and surrounding glass surface showed 7.1-/+5.7% and 4.3-/+1.7% cell death, respectively. Under cross-polarized light, the edge of the PS disc showed a low degree of birefringence whereas the centre of the disc did not. We also detached the PS disc and applied various weights (0.0 g to 40 g) to the disc at 100 degrees C for 2 hours and then cooled rapidly at 4 degrees C. We found that birefringence developed with stress to PS. NBT II cells grown on stressed PS showed an average of 55.8-/+14.1% cell death after a fluid shear force while cells on the glass surfaces resulted in only 5.0-/+2.7% cell death. Interestingly, increased birefringence is associated with increased lipophilicity on stressed PS, as determined by Nile Red staining. We propose that NBT II cell interaction with certain molecular characteristics of stressed PS results in altered cell membrane sensitivity to mechanical forces.

Biased interpretations of ambiguous bodily threat information in adolescents with chronic pain.

Adult patients with chronic pain are consistently shown to interpret ambiguous health and bodily information in a pain-related and threatening way. This interpretation bias may play a role in the development and maintenance of pain and disability. However, no studies have yet investigated the role of interpretation bias in adolescent patients with pain, despite that pain often first becomes chronic in youth. We administered the Adolescent Interpretations of Bodily Threat (AIBT) task to adolescents with chronic pain (N = 66) and adolescents without chronic pain (N = 74). Adolescents were 10 to 18 years old and completed the study procedures either at the clinic (patient group) or at school (control group). We found that adolescents with chronic pain were less likely to endorse benign interpretations of ambiguous pain and bodily threat information than adolescents without chronic pain, particularly when reporting on the strength of belief in those interpretations being true. These differences between patients and controls were not evident for ambiguous social situations, and they could not be explained by differences in anxious or depressive symptoms. Furthermore, this interpretation pattern was associated with increased levels of disability among adolescent patients, even after controlling for severity of chronic pain and pain catastrophizing. The current findings extend our understanding of the role and nature of cognition in adolescent pain, and provide justification for using the AIBT task in longitudinal and training studies to further investigate causal associations between interpretation bias and chronic pain.

Child attention to pain and pain tolerance are dependent upon anxiety and attention control: An eye-tracking study.

BACKGROUND: Pain is common and can be debilitating in childhood. Theoretical models propose that attention to pain plays a key role in pain outcomes, however, very little research has investigated this in youth. This study examined how anxiety-related variables and attention control interacted to predict children's attention to pain cues using eye-tracking methodology, and their pain tolerance on the cold pressor test (CPT). METHODS: Children aged 8-17 years had their eye-gaze tracked whilst they viewed photographs of other children displaying painful facial expressions during the CPT, before completing the CPT themselves. Children also completed self-report measures of anxiety and attention control. RESULTS: Findings indicated that anxiety and attention control did not impact children's initial fixations on pain or neutral faces, but did impact how long they dwelled on pain versus neutral faces. For children reporting low levels of attention control, higher anxiety was associated with less dwell time on pain faces as opposed to neutral faces, and the opposite pattern was observed for children with high attention control. Anxiety and attention control also interacted to predict pain outcomes. For children with low attention control, increasing anxiety was associated with anticipating more pain and tolerating pain for less time. CONCLUSIONS: This is the first study to examine children's attention to pain cues using eye-tracking technology in the context of a salient painful experience. Data suggest that attention control is an important moderator of anxiety on multiple outcomes relevant to young people's pain experiences. SIGNIFICANCE: This study uses eye tracking to study attention to pain cues in children. Attention control is an important moderator of anxiety on attention bias to pain and tolerance of cold pressor pain in youth.

Mental Imagery-Based Training to Modify Mood and Cognitive Bias in Adolescents: Effects of Valence and Perspective.

Mental imagery has a powerful impact on emotion and cognitive processing in adults, and is implicated in emotional disorders. Research suggests the perspective adopted in mental imagery modulates its emotional impact. However, little is known about the impact of mental imagery in adolescence, despite adolescence being the key time for the onset of emotional dysfunction. We administered computerised positive versus mixed valence picture-word mental imagery training to male adolescent participants (N = 60, aged 11-16 years) across separate field and observer perspective sessions. Positive mood increased more following positive than mixed imagery; pleasantness ratings of ambiguous pictures increased following positive versus mixed imagery generated from field but not observer perspective; negative interpretation bias on a novel scrambled sentences task was smaller following positive than mixed imagery particularly when imagery was generated from field perspective. These findings suggest positive mental imagery generation alters mood and cognition in male adolescents, with the latter moderated by imagery perspective. Identifying key components of such training, such as imagery perspective, extends understanding of the relationship between mental imagery, mood, and cognition in adolescence.

The hepatitis C virus internal ribosome entry site adopts an ion-dependent tertiary fold.

Hepatitis C virus (HCV) contains an internal ribosome entry site (IRES) located in the 5' untranslated region of the genomic RNA that drives cap-independent initiation of translation of the viral message. The approximate secondary structure and minimum functional length of the HCV IRES are known, and extensive mutagenesis has established that nearly all secondary structural domains are critical for activity. However, the presence of an IRES RNA tertiary fold and its functional relevance have not been established. Using chemical and enzymatic probes of the HCV IRES RNA in solution, we show that the IRES adopts a unique three-dimensional structure at physiological salt concentrations in the absence of additional cofactors or the translation apparatus. Folding of the IRES involves cooperative uptake of magnesium and is driven primarily by charge neutralization. This tertiary structure contains at least two independently folded regions which closely correspond to putative binding sites for the 40 S ribosomal subunit and initiation factor 3 (eIF3). Point mutations that inhibit IRES folding also inhibit its function, suggesting that the IRES tertiary structure is essential for translation initiation activity. Chemical and enzymatic probing data and small-angle X-ray scattering (SAXS) experiments in solution show that upon folding, the IRES forms an extended structure in which functionally important loops are exposed. These results suggest that the 40 S ribosomal subunit and eIF3 bind an HCV IRES that is prefolded to spatially organize recognition domains.

Association between serrated polyps and the risk of synchronous advanced colorectal neoplasia in average-risk individuals.

BACKGROUND: Serrated polyps of the colorectum have distinct histological features and malignant potential. AIM: To assess the association between the presence of serrated polyps and synchronous advanced colorectal neoplasia. METHODS: Among 4989 asymptomatic Chinese individuals aged 50-70 years who underwent screening colonoscopy, 281 cases with advanced neoplasia (adenoma ≥1 cm, with tubulovillous/villous histology, with high-grade dysplasia, or invasive adenocarcinoma) were compared with 4708 controls without advanced neoplasia for age, sex, smoking history, body mass index, family history of colorectal cancer and the presence of serrated polyps. Independent predictors of advanced neoplasia were determined by multivariate logistic regression analysis. RESULTS: The prevalence of advanced neoplasia and serrated polyps (excluding small distal hyperplastic polyps) was 5.7% and 5.6%, respectively. 3.7% and 0.4% subjects had proximal and large (≥10 mm) serrated polyps, respectively. Independent predictors of synchronous advanced colorectal neoplasia were the presence of sessile serrated adenomas (OR: 4.52; 95% CI: 2.40-8.49), proximal serrated polyps (OR: 2.23, 95% CI: 1.38-3.60), large serrated polyps (OR: 59.25; 95% CI: 18.85-186.21), hyperplastic polyps (OR: 1.66; 95% CI: 1.03-2.67), three or more serrated polyps (OR: 4.86; 95% CI: 1.24-19.15) and one or more non-advanced tubular adenomas (OR: 3.58, 95% CI: 2.59-4.96). CONCLUSION: Detection of proximal, sessile and/or large serrated polyps at screening colonoscopy is independently associated with an increased risk for synchronous advanced neoplasia.

A novel recombinant single-chain hepatitis C virus NS3-NS4A protein with improved helicase activity.

Hepatitis C virus (HCV) nonstructural protein 3 (NS3) has been shown to possess protease and helicase activities and has also been demonstrated to spontaneously associate with nonstructural protein NS4A (NS4A) to form a stable complex. Previous attempts to produce the NS3/NS4A complex in recombinant baculovirus resulted in a protein complex that aggregated and precipitated in the absence of nonionic detergent and high salt. A single-chain form of the NS3/NS4A complex (His-NS4A21-32-GSGS-NS3-631) was constructed in which the NS4A core peptide is fused to the N-terminus of the NS3 protease domain as previously described (Taremi et al., 1998). This protein contains a histidine tagged NS4A peptide (a.a. 21-32) fused to the full-length NS3 (a.a. 3-631) through a flexible tetra amino acid linker. The recombinant protein was expressed to high levels in Escherichia coli, purified to homogeneity, and examined for NTPase, nucleic acid unwinding, and proteolytic activities. The single-chain recombinant NS3-NS4A protein possesses physiological properties equivalent to those of the NS3/NS4A complex except that this novel construct is stable, soluble and sixfold to sevenfold more active in unwinding duplex RNA. Comparison of the helicase activity of the single-chain recombinant NS3-NS4A with that of the full-length NS3 (without NS4A) and that of the helicase domain alone suggested that the presence of the protease domain and at least the NS4A core peptide are required for optimal unwinding activity.

Evolutionary relationship of hepatitis C, pesti-, flavi-, plantviruses, and newly discovered GB hepatitis agents.

Two flavivirus-like viruses, GB virus-A (GBV-A) and GB virus-B (GBV-B), were recently identified in the GB hepatitis agent, and are distinct from the hepatitis A to E viruses. The putative helicase domain of GBV-A and GBV-B was found to have amino acid sequence homology with hepatitis C virus (HCV), and distantly, is also related to pestiviruses, flaviviruses, and plant viruses. A phylogenetic tree construction showed that GBVs and HCV are closely related, and they are clustered with pestiviruses, flaviviruses and plant viruses in that order.