Cas9�CcrRNA ribonucleoprotein complex mediates specific DNA cleavage for adaptive immunity in bacteria

Clustered, regularly interspaced, short palindromic repeats (CRISPR)/CRISPR-associated (Cas) systems provide adaptive immunity against viruses and plasmids in bacteria and archaea. The silencing of invading nucleic acids is executed by ribonucleoprotein complexes preloaded with small, interfering CRISPR RNAs (crRNAs) that act as guides for targeting and degradation of foreign nucleic acid. Here, we demonstrate that the Cas9–crRNA complex of the Streptococcus thermophilus CRISPR3/Cas system introduces in vitro a double-strand break at a specific site in DNA containing a sequence complementary to crRNA. DNA cleavage is executed by Cas9, which uses two distinct active sites, RuvC and HNH, to generate site-specific nicks on opposite DNA strands. Results demonstrate that the Cas9–crRNA complex functions as an RNA-guided endonuclease with RNA-directed target sequence recognition and protein-mediated DNA cleavage. These findings pave the way for engineering of universal programmable RNA-guided DNA endonucleases.     

Design and performance of a multisensor heart failure monitoring algorithm: results from the multisensor monitoring in congestive heart failure (MUSIC) study

BackgroundRemote monitoring of heart failure (HF) patients may help in the early detection of acute decompensation before the onset of symptoms, providing the opportunity for early intervention to reduce HF-related hospitalizations, improve outcomes, and lower costs.Methods and ResultsMUSIC is a multicenter nonrandomized study designed to develop and validate an algorithm for prediction of impending acute HF decompensation with the use of physiologic signals obtained from an external device adhered to the chest. A total of 543 HF patients (206 development, 337 validation) with ejection fraction ≤40% and a recent HF admission were enrolled. Patients were remotely monitored for 90 days using a multisensor device. Accounting for device failure and patient withdrawal, 314 patients (114 development, 200 validation) were included in the analysis. Development patient data were used to develop a multiparameter HF detection algorithm. Algorithm performance in the development cohort had 65% sensitivity, 90% specificity, and a false positive rate of 0.7 per patient-year for detection of HF events. In the validation cohort, algorithm performance met the prespecified end points with 63% sensitivity, 92% specificity, and a false positive rate of 0.9 per patient-year. The overall rate of significant adverse skin response was 0.4%.ConclusionUsing an external multisensor monitoring system, an HF decompensation prediction algorithm was developed that met the prespecified performance end point. Further studies are required to determine whether the use of this system will improve patient outcomes.     

Mean CD4 cell count changes in patients failing a first-line antiretroviral therapy in resource-limited settings

ABSTRACT: BACKGROUND: Changes in CD4 cell counts are poorly documented in individuals with low or moderate-level viremia while on antiretroviral treatment (ART) in resource-limited settings. We assessed the impact of on-going HIV-RNA replication on CD4 cell count slopes in patients treated with a first-line combination ART. METHOD: Naive patients on a first-line ART regimen with at least two measures of HIV-RNA available after ART initiation were included in the study. The relationships between mean CD4 cell count change and HIV-RNA at 6 and 12 months after ART initiation (M6 and M12) were assessed by linear mixed models adjusted for gender, age, clinical stage and year of starting ART. RESULTS: 3,338 patients were included (14 cohorts, 64% female) and the group had the following characteristics: a median follow-up time of 1.6 years, a median age of 34 years, and a median CD4 cell count at ART initiation of 107 cells/uL. All patients with suppressed HIV-RNA at M12 had a continuous increase in CD4 cell count up to 18 months after treatment initiation. By contrast, any degree of HIV-RNA replication both at M6 and M12 was associated with a flat or a decreasing CD4 cell count slope. Multivariable analysis using HIV-RNA thresholds of 10,000 and 5,000 copies confirmed the significant effect of HIV-RNA on CD4 cell counts both at M6 and M12. CONCLUSION: In routinely monitored patients on an NNRTI-based first-line ART, on-going low-level HIV-RNA replication was associated with a poor immune outcome in patients who had detectable levels of the virus after one year of ART.     

Liver transplantation for bariatric surgery-related liver failure: a systematic review of a rare condition

BackgroundProtein malnutrition and bacterial overgrowth occurring after bariatric surgery (BS) might cause severe liver failure (LF) needing liver transplantation (LT).ObjectivesTo evaluate indications and outcomes of LT for BS-related LF.SettingUniversity hospital in France.MethodsThe EMBASE, MEDLINE, and COCHRANE central databases were systematically searched according to the PRISMA criteria from inception up through December 2017 for articles describing LT for LF after BS.ResultsFourteen studies reporting 36 patients listed for LT, of which 32 underwent the procedure, were retained. The types of previously performed BS included jejunoileal bypass (n = 16), bilio-pancreatic diversion according to Scopinaro (n = 14) or with duodenal switch (n = 3), bilio-intestinal bypass (n = 1), long-limb Roux-en-Y gastric bypass (n = 1), and single anastomosis omega gastric bypass (n = 1). Liver failure developed a median of 20 months after BS (mean ± SD: 105 ± 121 mo; range, 5–300 mo). This interval of time was significantly shorter after biliopancreatic diversion than jejunoileal bypass (mean ± SD: 22 ± 21 mo versus 269 ± 27 mo; P = .0001). Four patients (11.1%) died while on the waiting list for LT, and 4 more (12.5%) died after LT. Morbidity and liver retransplantation were reported in 8 (25%) and 2 (6.2%) patients, respectively. Twenty-one patients (65.6%) had their BS procedure reversed (1 patient before, 15 patients during, and 5 patients after LT, respectively). Biopsy-proven steatosis recurrence after LT was reported in 6 patients (18.7%), 4 of whom did not have BS reversal.ConclusionsSevere LF occurring after BS, although rare, might require LT. When indicated, LT is effective at restoring liver function, even when BS reversal is performed synchronously.