Cytoplasmic CUG RNA Foci Are Insufficient to Elicit Key DM1 Features

The genetic basis of myotonic dystrophy type I (DM1) is the expansion of a CTG tract located in the 3′ untranslated region of DMPK. Expression of mutant RNAs encoding expanded CUG repeats plays a central role in the development of cardiac disease in DM1. Expanded CUG tracts form both nuclear and cytoplasmic aggregates, yet the relative significance of such aggregates in eliciting DM1 pathology is unclear. To test the pathophysiology of CUG repeat encoding RNAs, we developed and analyzed mice with cardiac-specific expression of a beta-galactosidase cassette in which a (CTG)₄₀₀ repeat tract was positioned 3′ of the termination codon and 5′ of the bovine growth hormone polyadenylation signal. In these animals CUG aggregates form exclusively in the cytoplasm of cardiac cells. A key pathological consequence of expanded CUG repeat RNA expression in DM1 is aberrant RNA splicing. Abnormal splicing results from the functional inactivation of MBNL1, which is hypothesized to occur due to MBNL1 sequestration in CUG foci or from elevated levels of CUG-BP1. We therefore tested the ability of cytoplasmic CUG foci to elicit these changes. Aggregation of CUG RNAs within the cytoplasm results both in Mbnl1 sequestration and in approximately a two fold increase in both nuclear and cytoplasmic Cug-bp1 levels. Significantly, despite these changes RNA splice defects were not observed and functional analysis revealed only subtle cardiac dysfunction, characterized by conduction defects that primarily manifest under anesthesia. Using a human myoblast culture system we show that this transgene, when expressed at similar levels to a second transgene, which encodes expanded CTG tracts and facilitates both nuclear focus formation and aberrant splicing, does not elicit aberrant splicing. Thus the lack of toxicity of cytoplasmic CUG foci does not appear to be a consequence of low expression levels. Our results therefore demonstrate that the cellular location of CUG RNA aggregates is an important variable that influences toxicity and support the hypothesis that small molecules that increase the rate of transport of the mutant DMPK RNA from the nucleus into the cytoplasm may significantly improve DM1 pathology.     

Oxidative stress increases susceptibility of Mycobacterium tuberculosis to isoniazid

Isoniazid is a first-line antibiotic used in the treatment of infections caused by Mycobacterium tuberculosis. Isoniazid is a prodrug requiring oxidative activation by the catalase-peroxidase hemoprotein, KatG. Resistance to isoniazid can be obtained by point mutations in the katG gene, with one of the most common being a threonine-for-serine substitution at position 315 (S315T). The S315T mutation is found in more than 50% of isoniazid-resistant clinical isolates and results in an approximately 200-fold increase in the MIC of isoniazid compared to that for M. tuberculosis H37Rv. In the present study we investigated the hypothesis that superoxide plays a role in KatG-mediated isoniazid activation. Plumbagin and clofazimine, compounds capable of generating superoxide anion, resulted in a lower MIC of isoniazid for M. tuberculosis H37Rv and a strain carrying the S315T mutation. These agents did not cause as great of an increase in isoniazid susceptibility in the mutant strain when the susceptibilities were assessed by using the inhibitory concentration that causes a 50% decrease in growth. These results provide evidence that superoxide can play a role in isoniazid activation. Since clofazimine alone has antitubercular activity, the observation of synergism between clofazimine and isoniazid raises the interesting possibility of using both drugs in combination to treat M. tuberculosis infections.     

Electromagnetic Interference (EMI) and arrhythmic events in ICD patients undergoing gastrointestinal procedures

BACKGROUND: The objective was to determine the effect of electromagnetic interference (EMI) in patients undergoing gastrointestinal endoscopy. The implantable cardioverter-defibrillator (ICD) is the primary therapeutic modality for patients at risk for sudden cardiac death. One potential problem with ICDs is interactions with electrical devices and medical procedures causing EMI or triggering arrhythmic events. Endoscopy frequently employs electrocautery (EC) for diagnosis and treatment of gastrointestinal diseases. Current guidelines advise inactivating ICDs before any surgical procedure. There is limited information on management of ICDs during endoscopy with or without EC. We prospectively evaluated patients with ICDs undergoing endoscopic procedures at our institution. METHODS AND RESULTS: Forty-one ICD patients underwent 52 gastrointestinal endoscopies over 17 months. The mean age of the population was 66 years (51-83). There were 28 men and 13 women. Thirteen patients had single chamber devices, 25 had dual chamber devices, and 2 had biventricular ICDs. The mean tachyarrhythmia detection rate programmed was 164.7 bpm (125-188). Eighteen procedures (43.9%) required biopsy, coagulation, or polypectomy. Of these, 10 (55%) required the use of EC. Only unipolar EC with mean current 19.6 mA was used. All ICDs were programmed to detection-only with therapies off. Sensitivity was left at nominal programmed settings. Post procedure interrogation showed no detection of EMI or tachyarrhythmic events. CONCLUSIONS: Our study shows no EMI or arrhythmic events triggered during endoscopic procedures in patients with pectorally implanted transvenous ICDs. Routine practice of programming ICDs off for gastrointestinal procedures may not be necessary. However, larger studies are needed before change in current recommendations.     

Risk factors for piperacillin-tazobactam-resistant Pseudomonas aeruginosa among hospitalized patients

Antimicrobial resistance is an emerging problem with Pseudomonas aeruginosa. This study determined risk factors for the recovery of piperacillin-tazobactam-resistant P. aeruginosa from clinical cultures from hospitalized patients. A case-control study design was used to compare two groups of case patients with control patients. The first group of case patients was defined by nosocomial isolation of piperacillin-tazobactam-resistant P. aeruginosa, and the second group of cases yielded piperacillin-tazobactam-susceptible P. aeruginosa. Controls were selected in a 6:1 ratio from the same medical or surgical services among which piperacillin-tazobactam-resistant P. aeruginosa arose in patients. Risk factors analyzed included antimicrobial drug exposure, comorbid conditions, and demographics. Bivariate and multivariable analyses were performed. Piperacillin-tazobactam-resistant P. aeruginosa was isolated from 179 patients, and piperacillin-tazobactam-susceptible P. aeruginosa was isolated from 624 patients over a 2.5-year period. Piperacillin-tazobactam (odds ratio [OR] = 6.82; 95% confidence interval [CI], 4.56 to 10.21), imipenem (OR = 2.42; 95% CI, 1.19 to 4.94), aminoglycosides (OR = 2.18; 95% CI, 1.44 to 3.28), vancomycin (OR = 1.87; 95% CI, 1.21 to 2.89), and broad-spectrum cephalosporins (OR = 2.38; 95% CI, 1.45 to 3.88) were the antibiotics associated with the isolation of piperacillin-tazobactam-resistant P. aeruginosa. Exposure to vancomycin (OR = 1.53; 95% CI, 1.13 to 2.06) or ampicillin-sulbactam (OR = 2.28; 95% CI, 1.62 to 3.21) was associated with recovery of piperacillin-tazobactam-susceptible P. aeruginosa. In this study, antibiotics associated with piperacillin-tazobactam-susceptible P. aeruginosa were different from antibiotics associated with piperacillin-tazobactam-resistant P. aeruginosa. Piperacillin-tazobactam was a strong risk factor for piperacillin-tazobactam-resistant P. aeruginosa. Our results suggest that the nosocomial isolation of piperacillin-tazobactam-resistant P. aeruginosa may be affected by multiple antibiotics.     

Late onset neonatal anaemia due to maternal anti-Ge: possible association with destruction of eythroid progenitors

There have been no reports of severe haemolytic disease of the newborn (HDN) due to Gerbich (Ge) antibodies. Two babies with HDN due to anti-Ge3, both born to the same mother, are described. The anti-Ge appeared in the first pregnancy and was not detectable in the first trimester, the babies' reticulocyte and bilirubin values were not greatly elevated (similar to HDN due to Kell antibodies), and the anaemia in both cases was either not apparent or not severe until 2 to 4 weeks after birth. Ge antigens are found on glycophorins (GPs) C and D; GPC, like Kell, has been shown to be expressed early on erythroid progenitor cells. The maternal anti-Ge3 was shown to promote phagocytosis of Ge+ early erythroid progenitors by monocytes (similar to what has been reported with anti-K and K+ progenitor cells). Thus, anti-Ge3 may cause immune destruction of erythroid progenitors and possibly suppression of erythropoiesis (which would explain the reticulocyte and bilirubin values seen in both cases). Anti-Ge3 appears to be capable of causing severe HDN. We suggest that babies born to mothers with anti-Ge should have their haemoglobin concentrations monitored for signs of anaemia for several weeks after birth. Functional assays may prove useful.     

Biomechanical tolerance of whole lumbar spines in straightened posture subjected to axial acceleration

Quantification of biomechanical tolerance is necessary for injury prediction and protection of vehicular occupants. This study experimentally quantified lumbar spine axial tolerance during accelerative environments simulating a variety of military and civilian scenarios. Intact human lumbar spines (T12‐L5) were dynamically loaded using a custom‐built drop tower. Twenty‐three specimens were tested at sub‐failure and failure levels consisting of peak axial forces between 2.6 and 7.9 kN and corresponding peak accelerations between 7 and 57 g. Military aircraft ejection and helicopter crashes fall within these high axial acceleration ranges. Testing was stopped following injury detection. Both peak force and acceleration were significant (p < 0.0001) injury predictors. Injury probability curves using parametric survival analysis were created for peak acceleration and peak force. Fifty‐percent probability of injury (95%CI) for force and acceleration were 4.5 (3.9–5.2 kN), and 16 (13–19 g). A majority of injuries affected the L1 spinal level. Peak axial forces and accelerations were greater for specimens that sustained multiple injuries or injuries at L2–L5 spinal levels. In general, force‐based tolerance was consistent with previous shorter‐segment lumbar spine testing (3–5 vertebrae), although studies incorporating isolated vertebral bodies reported higher tolerance attributable to a different injury mechanism involving structural failure of the cortical shell. This study identified novel outcomes with regard to injury patterns, wherein more violent exposures produced more injuries in the caudal lumbar spine. This caudal migration was likely attributable to increased injury tolerance at lower lumbar spinal levels and a faster inertial mass recruitment process for high rate load application. Published 2017. This article is a U.S. Government work and is in the public domain in the USA. J Orthop Res 36:1747–1756, 2018.     

Predictive Validity of the Global Assessment Form Used in a Final-year Undergraduate Rotation in Emergency Medicine

OBJECTIVES: To determine whether the predictive validity of Global Assessment Form (GAF) knowledge subdomain marks exceeds that of the overall GAF marks with respect to written examination marks for an undergraduate rotation in emergency medicine, and to determine the interdependence between subdomain marks on the GAF. METHODS: Final-year clinical clerks completing a four-week rotation through the emergency departments of a university teaching center were evaluated using both a ten-subdomain GAF for clinical performance and an independent written examination. The GAF and examination marks were prospectively obtained for clinical clerks over a two-year period. Pearson correlations were calculated between examination marks and both the GAF knowledge subdomain and the GAF overall mark. Olkin's Z score was calculated to determine the significance of the difference between correlations. Interdependencies between subdomains of the GAF were calculated using an alpha coefficient and inter-item correlations. RESULTS: Data sets were reviewed for 347 clinical clerks. Nine sets of data were excluded (incomplete evaluations); 338 sets were analyzed. Means for overall clinical mark and examination mark were 80.11% (SD = 4.375) and 81 (SD = 7.66). Among subdomains, knowledge had the highest correlation with the examination mark (0.19). Overall clinical marks had lower correlation with the examination marks (0.169); the difference was not significant (Olkin's Z = 0.40). The correlation of the examination marks with the average marks of all subdomains excluding knowledge was even lower (0.12). The tenitem alpha for the GAF was 0.92. CONCLUSIONS: Clinical GAF assessments of knowledge, as measured by written examination, do not appear to be any more predictive than overall clinical impression. There is substantial consistency between subdomain scores, suggesting that assessors are not effectively discriminating between them when assigning marks.     

A randomized, double-blind, placebo-controlled study of the efficacy and tolerability of policosanol in adolescents with type II hypercholesterolemia

Background: Atherosclerosis begins in childhood and is influenced by risk factors for coronary heart disease (CHD), of which hypercholesterolemia is crucial. The rationale for treating hypercholesterolemia in childhood is to limit atherosclerosis development, for which adherence to a cholesterol-lowering diet is the first-choice therapy. Nevertheless, pharmacological intervention with bile acid-binding resins may be prescribed for patients older than 10 years, mainly those with family history of CHD, multiple risk factors, and/or severe hypercholesterolemia. Resins are effective and tolerable in this population, but their clinical use has been limited because of poor compliance due to unpalatability; other effective cholesterol-lowering drugs have not been recommended in this population because of the potential impact of drug-related adverse effects such as increases in transaminases, myopathies, and gastrointestinal disturbances. Thus, the need for safer, easy-to-take, and effective cholesterol-lowering agents for this population continues. Policosanol is a mixture of higher primary aliphatic alcohols purified from sugar cane wax with cholesterol-lowering effects proven in patients with type II hypercholesterolemia and dyslipidemia due to type 2 diabetes mellitus. Policosanol shows good safety and tolerability profiles, with no evidence of drug-related adverse events (AEs) to date. This background supports the idea that policosanol could be a good candidate for treating hypercholesterolemia in children and adolescents, but it requires clinical demonstration.Objective: This 12-week study was undertaken to investigate the cholesterol-lowering effects and tolerability of policosanol in hypercholesterolemic patients aged 11 to 19 years.Methods: In this randomized, double-blind, placebo-controlled study, after 4 weeks of dietary stabilization, adolescents with type II hypercholesterolemia were randomly assigned (1:1 ratio) to receive placebo or policosanol 5-mg tablets once daily for 12 weeks. Physical examinations were performed, and lipid profiles and blood samples were obtained at baseline and after 6 and 12 weeks of therapy. The treatment was considered effective if mean reductions of low-density lipoprotein cholesterol (LDL-C) were >15%. In addition, the percentages of patients reaching final values of LDL-C <3.4 mmol/L and optimal values of <2.8 mmol/L were also evaluated. The doses were doubled if LDL-C values were ≥3.4 mmol/L after 6 weeks of therapy. The incidence of AEs and compliance with study medications were also evaluated after 6 and 12 weeks of treatment.Results: Fifty-five patients were enrolled in the study (28 policosanol, 27 placebo). Twenty-three patients (17 placebo, 6 policosanol) required dose titration at 6 weeks. After 12 weeks of therapy, policosanol significantly decreased LDL-C with respect to baseline and placebo (both P < 0.001), showing a mean reduction of 32.6%. Total cholesterol (TC) and TC/high-density lipoprotein cholesterol (HDL-C) and LDL-C/HDL-C ratios were reduced by 21.9%, 27.8%, and 37.2%, respectively, in the policosanol group (P < 0.001, compared with baseline and placebo). HDL-C rose 10.1% (P < 0.001), compared with baseline and placebo. Triglycerides were unaffected by policosanol. LDL-C, TC, and both atherogenic ratios were reduced significantly in the policosanol group (P < 0.001), and significant increases in HDL-C values were observed at the 6-week interim checkup (P < 0.001 vs baseline, P < 0.01 vs placebo). Twenty-five (89.3%) of 28 patients in the policosanol group showed LDL-C reductions >15% compared with 2 (7.4%) of 27 patients in the placebo group (P < 0.001). In addition, 26 (92.8%) of 28 policosanol patients reached LDL-C values < 3.4 mmol/L compared with 4 (14.8%) of 27 patients in the placebo group (P < 0.001). Likewise, the response rate for achievement of optimal values (LDL-C < 2.8 mmol/L) was also larger in the policosanol group (20/28; 71.4%) than in the placebo group (0/27; 0.0%) (P < 0.001). Policosanol was well tolerated, with no drug-related effects found on physical examination. Blood biochemistry determinations revealed significantly lower alanine aminotransferase levels in the policosanol group after 6 weeks of therapy compared with placebo (P < 0.05), as well as significant reductions in aspartate aminotransferase levels at 6 weeks (P < 0.01) and 12 weeks (P < 0.05) compared with baseline. No patients withdrew from the study, and only 3 patients (2 placebo, 1 policosanol) experienced mild AEs during the study; the placebo patients reported abdominal pain and constipation (1 each), and the policosanol patient reported polyphagia.Conclusions: Policosanol 5 mg/d appears to be well tolerated and effective as short-term treatment of hypercholesterolemia in adolescents.     

Elevated C-reactive protein in acute coronary syndrome presentation is an independent predictor of long-term mortality and heart failure

OBJECTIVES: To assess the ability of C-reactive protein (CRP) to predict long-term outcomes in a chest pain population. DESIGN AND METHODS: CRP was measured at presentation in 446 emergency department patients with acute coronary syndromes. All-cause mortality and hospital discharges for acute myocardial infarction (AMI) and congestive heart failure (CHF) were obtained for up to 8 years following the event. RESULTS: Kaplan-Meier analyses indicated that patients with CRP concentrations above the American Heart Association scientific statement cut-off had a higher rate for death and CHF admissions. After adjusting for troponin concentrations, in a Cox proportional hazard model, only CRP concentrations indicative of an acute phase response (i.e., >7.44 mg/L) were associated with a significant risk for death after 5 years and CHF readmission after 2 years. CONCLUSIONS: Patients presenting early with chest pain with elevated CRP concentrations have a greater long-term risk for death and heart failure.