Enhanced Optical Fiber for Distributed Acoustic Sensing beyond the Limits of Rayleigh Backscattering.

We report on engineered fibers with enhanced optical backscattering that exceeds Rayleigh scattering limits by more than one order of magnitude. We measure attenuation less than 0.5 dB/km from 1,300 to 1,650 nm. By controlling the enhanced backscatter over a 1.5-km length, we compensate for this attenuation, resulting in a higher backscatter signal at the end of the fiber. We demonstrate that the scattering strength may be stabilized for operation at temperatures above 200°C for at least 3 weeks. We show that the deleterious signal distortion due to the Kerr nonlinearity is within 10% of standard fiber. We then report on the use of these fibers in distributed acoustic sensing (DAS) measurements. A significant increase in acoustic signal-to-noise ratio leads to the possibility of improved spatial resolution in the enhanced fiber DAS system.

B-type peptides to predict post-liver transplant mortality: systematic review and meta-analysis.

Background: Cirrhotic patients undergoing liver transplantation are at risk of cardiac complications. Brain natriuretic peptide (BNP) and amino terminal brain natriuretic peptide (NT-BNP) are used in cardiac risk stratification. Their significance in predicting mortality risk in cirrhotic patients during or after liver transplantation is unknown. We conducted a systematic review and meta-analysis to answer this question. Methods: An electronic search of EMBASE, MEDLINE, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews (2005-September 2016), Google Scholar, and study bibliographies was conducted. Study quality was determined, and demographic and outcome data were gathered. Random effects meta-analyses of mortality-based BNP and NT-BNP level or presence of post-transplant heart failure were conducted. Results: Seven studies including 2,010 patients were identified. Demographics were similar between patients with high or low BNP or NT-BNP levels. Hepatitis C was the most prevalent etiology of cirrhosis (38%). Meta-analysis revealed a pooled relative risk of 3.1 (95% CI 1.9% to 5.0%) for post-transplant mortality based on elevated BNP or NT-BNP level. Meta-analysis also revealed a pooled relative risk of 1.6 (95% CI 1.3% to 2.1%) for post-transplant mortality if patients had demonstrated post-transplant heart failure. Conclusions: Our analysis suggests that BNP or NT-BNP measurement may help in risk stratification and provides data on post-operative mortality in cirrhotic patients undergoing liver transplantation. Discriminatory thresholds are higher in cirrhotic patients relative to prior studies with non-cirrhotic patients. However, the number of analyzed studies is limited, and our findings should be validated further through larger, prospective studies.

Hepatocellular carcinoma screening practices among patients with chronic hepatitis B by Canadian gastroenterologists and hepatologists: An online survey.

BACKGROUND: xpert guidelines recommend hepatocellular carcinoma (HCC) surveillance among patients with high-risk chronic hepatitis B (CHB); however, physician screening practices are often variable. METHODS: An online survey of HCC screening practice was distributed to members of the Canadian Association for the Study of the Liver. Data were analyzed using appropriate statistical tests with p < .05 significance. RESULTS: Of 71 respondents, 86% (n = 61) were gastroenterologists or hepatologists, and 72% (n = 51) reported having been in clinical practice for more than 5 years. A significant number of survey respondents performed HCC screening without consideration of concomitant non-alcoholic fatty liver disease (50.7%); non-Asian, non-African ethnicity (46.4%); and family history of HCC (28.6%). Most (67.6%) performed screening with ultrasound (US) at the time of specialty clinic visits, 28.2% had an automatic recall system, and only 2.8% referred back to primary care physicians to organize screening. More than half (54.9%) included alpha-fetoprotein in screening. Obstacles to screening included lack of an automatic recall system (42.9%), patient non-compliance (30.0%), and limited US/MRI access (17.1%). CONCLUSIONS: HCC screening practices with hepatitis B patients vary widely among Canadian specialists, especially in unique populations with limited data to inform screening recommendations. Implementation of an automatic recall system could potentially increase HCC surveillance.

Transplantation of a Liver Allograft From a Hepatitis C Virus Seropositive Donor With Previous Sustained Virologic Response to an Uninfected Recipient Suffering Steroid Refractory Acute Graft Rejection With No Evidence of HCV Transmission.

BACKGROUND: The goal of treating chronic hepatitis C virus (HCV) infection is sustained virologic response (SVR). There is concern that despite achieving SVR, replication-competent HCV may be sequestered at low levels within the liver and could theoretically reactivate with immunosuppression. We report transplantation of a HCV-seropositive liver donor, who achieved SVR, into a seronegative patient without HCV reactivation despite profound immunosuppression. METHOD: Retrospective chart review. RESULTS: We present a 21-year-old male who was HCV seronegative and received a liver transplant from a donor who had been treated for HCV and achieved SVR. The liver recipient, despite developing severe acute graft rejection and undergoing intense immunosuppression with T cell-depleting antibodies, did not become HCV RNA-positive with a follow up period of 8 months. The recipient was HCV seronegative before transplant, but became HCV seropositive immediately posttransplant. The antibodies were undetectable after 97 days, in keeping with a passive antibody transmission or B lymphocyte transmission with the graft. CONCLUSIONS: To the best of our knowledge, this is the first reported case of an HCV seropositive liver allograft transplanted into an HCV-negative recipient who subsequently received intense immunosuppression. This case, therefore, is an encouraging and novel step in liver transplantation, and demonstrates that SVR may be closer to a true "cure" of HCV in the donor population and that, even in circumstances of very potent immunosuppression in the recipient, this SVR is sustained.

Hepatitis B Awareness and Knowledge in Asian Communities in British Columbia.

Background. Our study examined hepatitis B virus (HBV) awareness and knowledge in Asian communities in British Columbia (BC). Methods. A statistical random sample representation of Chinese, Korean, Filipino, South Asian, and Southeast Asian populations in Greater Vancouver was surveyed by telephone. Multiple logistic regression analysis was performed to identify predictors of HBV knowledge. Results. General awareness of HBV was reported in 78.8% (798/1013). HBV awareness was the highest in Chinese (89%) and Filipino (88%) populations and the lowest in the South Asian (56%) population. "Reasonable" knowledge of HBV was elicited in 76.8% (778/1013). Higher HBV knowledge was associated with younger age (p = 0.014), higher education (p < 0.0001), Chinese ethnicity (p < 0.0001), and use of media (p = 0.01) and Internet (p = 0.024) for health information. Compared to the Chinese (OR = 1.0) population, "reasonable" knowledge of HBV was lower in Korean (OR = 0.3, 95% CI: 0.1-0.5), Filipino (OR = 0.3, 95% CI: 0.2-0.6), South Asian (OR = 0.3, 95% CI: 0.2-0.4), and Southeast Asian (OR = 0.3, 95% CI: 0.1-0.6) populations. 54.8% (555/1013) felt that HBV education was inadequate and 80.1% (811/1013) preferred HBV education in their native languages. Conclusion. Compared to the Chinese population, other Asian communities in BC have lower HBV awareness and knowledge. Public education should target older and less educated and Korean, Filipino, South Asian, and Southeast Asian populations in their native languages via media and Internet.

Collagenous enterocolitis manifesting as watery diarrhoea and iron-deficiency anaemia.

A 56-year-old Caucasian woman presented with epigastric pain, watery diarrhoea, bloating and flatulence following treatment with duloxetine and venlafaxine for anxiety and depression. Abdominal examination was benign. Blood work revealed haemoglobin of 96 g/L (115-160 g/L), iron 6 µmol/L (10-33 µmol/L), transferrin saturation 0.08 (0.20-0.55), ferritin 26 µg/L (15-180 µg/L), albumin 46 g/L (35-50 g/L), pre-albumin 293 mg/L (170-370 mg/L), total IgA 2.64 g/L (0.78-3.58 g/L) and anti-tTG IgA 5 units (<20 units). Faecal occult blood tests were 3/3 positive and stool cultures were negative. CT enterography was normal. Colonic biopsy revealed collagenous colitis, while duodenal biopsy showed collagenous sprue with blunted to completely flattened villi and markedly thickened subepithelial collagen table entrapping capillaries and lymphocytes. The patient started a gluten-free diet, loperamide and ferrous gluconate. Her symptoms resolved and a faecal immunochemical test performed 6 months later was negative.

Hepatitis C (chronic).

INTRODUCTION: About 60% to 85% of people infected with hepatitis C virus will go on to develop chronic hepatitis C, which is now believed to affect 3% of the world's population. METHODS AND OUTCOMES: We conducted a systematic overview and aimed to answer the following clinical questions: What are the effects of interferon-free treatments in treatment-naïve people with chronic hepatitis C infection without cirrhosis? What are the effects of interferon-free treatments in treatment-naïve people with chronic hepatitis C infection with cirrhosis? We searched: Medline, Embase, The Cochrane Library, and other important databases up to August 2014 (Clinical Evidence overviews are updated periodically; please check our website for the most up-to-date version of this review). RESULTS: After deduplication and removal of conference abstracts, 30 records were screened for inclusion in the review. Appraisal of titles and abstracts led to the exclusion of 11 studies and the further review of 19 full publications. Of the 19 full articles evaluated, two systematic reviews and one RCT were added. We performed a GRADE evaluation for two PICO combinations. CONCLUSIONS: In this systematic overview, we categorised the efficacy for 12 different intervention/comparison combinations, based on information relating to the effectiveness and safety of sofosbuvir (with or without ribavirin), sofosbuvir (with or without ribavirin) plus ledipasvir, and sofosbuvir (with or without ribavirin) plus simeprevir, all in people with and without cirrhosis.

Rate, delay and predictors of hepatitis C treatment in British Columbia.

BACKGROUND: The current treatment rate for chronic hepatitis C virus (HCV) infection is suboptimal despite the availability of efficacious antiviral therapy. OBJECTIVE: To determine the rate, delay and predictors of treatment in patients with chronic HCV infection. METHODS: A retrospective chart review of chronic HCV patients who were being evaluated at a tertiary hepatology centre in Vancouver, British Columbia, was performed. RESULTS: One hundred sixty-four patients with chronic HCV infection who were assessed for treatment between February 2008 and January 2013 were reviewed. Treatment was initiated in 25.6% (42 of 164). In multivariate analyses, male sex (OR 7.90 [95% CI 1.35 to 46.15]) and elevated alanine aminotransferase (ALT) level (>1.5 times the upper limit of normal) (OR 3.10 [95% CI 1.32 to 7.27]) were positive predictors of treatment, whereas active smoking (OR 0.09 [95% CI 0.02 to 0.53]) and Charlson comorbidity index (per point increase) (OR 0.47 [95% CI 0.27 to 0.83]) were negative predictors of treatment. The most common reasons for treatment deferral were no or minimal liver fibrosis in 57.7% (n=30), persistently normal ALT levels in 57.7% (n=30) and patient unreadiness in 28.8% (n=15). The most common reasons for treatment noninitiation were patient refusal in 59.1% (n=26), medical comorbidities in 36.4% (n=16), psychiatric comorbidities in 9.1% (n=4) and decompensated cirrhosis in 9.1% (n=4). There was a statistically significant difference in the median time delay from HCV diagnosis to general practitioner referral between the treated and untreated patients (66.3 versus 119.5 months, respectively [P=0.033]). The median wait time from general practitioner referral to hepatologist consult was similar between the treated and untreated patients (1.7 months versus 1.5 months, respectively [P=0.768]). Among the treated patients, the median time delay was 6.8 months from hepatologist consult to treatment initiation. CONCLUSIONS: The current treatment rate for chronic HCV infection remains suboptimal. Medical and psychiatric comorbidities represent a major obstacle to HCV treatment. Minimal hepatic fibrosis may no longer be a major reason for treatment deferral as more efficacious and tolerable antiviral therapies become available in the future. Greater educational initiatives for primary care physicians would promote early referral of patients. More nursing support would alleviate the backlog of patients awaiting treatment.

Hepatitis C drugs: the end of the pegylated interferon era and the emergence of all-oral interferon-free antiviral regimens: a concise review.

Between 2001 and 2011, the standard of care for chronic hepatitis C virus (HCV) infection was a combination of pegylated interferon (PEG-IFN) and ribavirin (RBV). In May 2011, boceprevir and telaprevir, two first-generation NS3/4A protease inhibitors, were approved in combination with PEG-IFN and RBV for 24 to 48 weeks in hepatitis C virus genotype 1 infections. In December 2013, simeprevir, a second-generation NS3/4A protease inhibitor, was approved for use with PEG-IFN and RBV for 12 weeks in genotype 1, while sofosbuvir, a NS5B nucleotide polymerase inhibitor, was approved for use with PEG-IFN and RBV for 12 weeks in genotypes 1 and 4, as well as with RBV alone for 12 weeks in genotype 2 and for 24 weeks in genotype 3. Sofosbuvir combined with simeprevir or an NS5A replication complex inhibitor (ledipasvir or daclatasvir) with or without RBV for 12 weeks in genotype 1 resulted in a sustained virological response >90%, irrespective of previous treatment history or presence of cirrhosis. Similarly impressive sustained virological response rates have been shown with ABT-450/r (ritonavir-boosted NS3/4A protease inhibitor)-based regimens in combination with other direct-acting antiviral agent(s) with or without RBV for 12 weeks in genotype 1. The optimal all-oral interferon-free antiviral regimen likely entails a combination of an NS5B nucleotide polymerase inhibitor with either a second-generation NS3/4A protease inhibitor or an NS5A replication complex inhibitor with or without RBV. Further research is needed to determine the role of resistance testing, clarify the optimal follow-up duration post-treatment, and evaluate the antiviral efficacy and safety in difficult-to-cure patient populations.

Rectal ulcers induced by systemic lupus erythematosus.

A 28-year-old woman presented with diarrhoea, haematochezia, tenesmus and rectal pain for 2 months. She was diagnosed with systemic lupus erythematosus (SLE) 8 years ago and remained on prednisone, azathioprine and hydroxychloroquine. Blood work revealed a positive ANA (antinuclear antibody test), anti-dsDNA 749 IU/mL (0-300 IU/mL), C3 0.22 g/L (0.65-1.65 g/L) and C4 0.05 g/L (0.16-0.60 g/L). Stool studies were unremarkable. MRI of the pelvis showed a rectum with eccentric wall thickening. Flexible sigmoidoscopy showed severe proctitis with multiple deep ulcers and diffuse submucosal haemorrhage. Rectal biopsy revealed crypt architectural distortion and reactive fibrosis in the lamina propria. The patient was given mesalamine suppository for 2 weeks with minimal improvement. Repeat flexible sigmoidoscopy showed a coalesced 3×4 cm full-thickness rectal ulcer. Therefore, the patient was given intravenous methylprednisolone for 3 days, followed by intravenous cyclophosphamide for 2 weeks. Her symptoms resolved and repeat flexible sigmoidoscopy showed fibrotic healing of the rectal ulcers.

Safety and efficacy of Hemospray® in upper gastrointestinal bleeding.

BACKGROUND: Hemospray (Cook Medical, USA) has recently been approved in Canada for the management of nonvariceal upper gastrointestional bleeding (UGIB). OBJECTIVE: To review the authors' experience with the safety and efficacy of Hemospray for treating UGIB. METHODS: A retrospective chart review was performed on patients who required endoscopic evaluation for suspected UGIB and were treated with Hemospray. RESULTS: From February 2012 to July 2013, 19 patients (mean age 67.6 years) with UGIB were treated with Hemospray. A bleeding lesion was identified in the esophagus in one (5.3%) patient, the stomach in five (26.3%) and duodenum in 13 (68.4%). Bleeding was secondary to peptic ulcers in 12 (63.2%) patients, Dieulafoy lesions in two (10.5%), mucosal erosion in one (5.3%), angiodysplastic lesions in one (5.3%), ampullectomy in one (5.3%), polypectomy in one (5.3%) and an unidentified lesion in one (5.3%). The lesions showed spurting hemorrhage in four (21.1%) patients, oozing hemorrhage in 11 (57.9%) and no active bleeding in four (21.1%). Hemospray was administered as monotherapy in two (10.5%) patients, first-line modality in one (5.3%) and rescue modality in 16 (84.2%). Hemospray was applied prophylactically to nonbleeding lesions in four (21.1%) patients and therapeutically to bleeding lesions in 15 (78.9%). Acute hemostasis was achieved in 14 of 15 (93.3%) patients. Rebleeding within seven days occurred in seven of 18 (38.9%) patients. Potential adverse events occurred in two (10.5%) patients and included visceral perforation and splenic infarct. Mortality occurred in five (26.3%) patients but the cause of death was unrelated to gastrointestinal bleeding with the exception of one patient who developed hemoperitoneum. CONCLUSIONS: The high rates of both acute hemostasis and recurrent bleeding suggest that Hemospray may be used in high-risk cases as a temporary measure or a bridge toward more definitive therapy.

EEG correlates of task engagement and mental workload in vigilance, learning, and memory tasks.

INTRODUCTION: The ability to continuously and unobtrusively monitor levels of task engagement and mental workload in an operational environment could be useful in identifying more accurate and efficient methods for humans to interact with technology. This information could also be used to optimize the design of safer, more efficient work environments that increase motivation and productivity. METHODS: The present study explored the feasibility of monitoring electroencephalo-graphic (EEG) indices of engagement and workload acquired unobtrusively and quantified during performance of cognitive tests. EEG was acquired from 80 healthy participants with a wireless sensor headset (F3-F4,C3-C4,Cz-POz,F3-Cz,Fz-C3,Fz-POz) during tasks including: multi-level forward/backward-digit-span, grid-recall, trails, mental-addition, 20-min 3-Choice Vigilance, and image-learning and memory tests. EEG metrics for engagement and workload were calculated for each 1 -s of EEG. RESULTS: Across participants, engagement but not workload decreased over the 20-min vigilance test. Engagement and workload were significantly increased during the encoding period of verbal and image-learning and memory tests when compared with the recognition/ recall period. Workload but not engagement increased linearly as level of difficulty increased in forward and backward-digit-span, grid-recall, and mental-addition tests. EEG measures correlated with both subjective and objective performance metrics. DISCUSSION: These data in combination with previous studies suggest that EEG engagement reflects information-gathering, visual processing, and allocation of attention. EEG workload increases with increasing working memory load and during problem solving, integration of information, analytical reasoning, and may be more reflective of executive functions. Inspection of EEG on a second-by-second timescale revealed associations between workload and engagement levels when aligned with specific task events providing preliminary evidence that second-by-second classifications reflect parameters of task performance.