Antibiotic susceptibility patterns of Helicobacter pylori and triple therapy in a high-prevalence area

This study aims to determine primary Helicobacter pylori resistance and its effect on eradication of the organism. Ninety-two Patients with dyspeptic symptoms were enrolled. H. pylori was cultured and antibiotic sensitivity was determined by the Epsilometer test (Etest) for clarithromycin (CLR), amoxicillin (AMX) and metronidazole (MTR). 23S ribosomal RNA (rRNA) point mutations associated with clarithromycin resistance were also detected. Patients were treated with omeprazole (40 mg daily), CLR (500 mg) and AMX (1g twice a day) for 14 days. A (14)C-urea breath test ((14)C-UBT) was repeated four weeks after completion of treatment to confirm eradication. Triple therapy failure was seen in 30(33%) Patients. The resistance rates were: CLR 33% (30/92), MTR 48% (44192) and AMX (2/92). Clarithromycin resistance (CLR-R) was present in the 16-39 age group in 21 (47%) (P=0.007) compared to nine (19%)in the 40-79 age group. CLR resistance was seen in 30 H. pylori isolates, 20 (67%) from Patients with non-ulcer dyspepsia (NUD), six (20%) with gastric ulcer (GU) and four (13%) with duodenal ulcer (DU). Triple therapy failure was associated with CLR-R in 28 (93%) (

Risk factors associated with Helicobacter pylori infection treatment failure in a high prevalence area

Triple therapy is commonly used for the treatment of Helicobacter pylori infection. We determined risk factors associated with its failure in compliant Patients focusing on H. pylori density, virulence marker and 23S ribosomal RNA (rRNA) point mutations associated with clarithromycin resistance. H. pylori infection was diagnosed by (14)C urea breath test ((14)C UBT) and rapid urease test or histology. Triple therapy with esomeprazole 20 mg b.i.d., amoxicillin 1 g b.i.d. and clarithromycin 500 mg b.i.d. was prescribed for 10 days. 14C UBT was repeated 4 weeks after treatment. In total, 111 Patients [69 (62%) males] with a mean age of 46 +/- 16 years were enrolled. The mean age of treatment failure was 39 +/- 14 years compared to 48 +/- 16 years with eradication (P=0.002). Treatment failure was associated with younger mean age, point mutations in the 23S rRNA gene of H. pylori and vacA s1a and m1 when associated with cagA negativity

Progress Toward Future Runway Management

The runway is universally acknowledged as a constraining factor to capacity in the National Airspace System (NAS). It follows that investigation of the effective use of runways, both in terms of selection and assignment, is paramount to the efficiency of future NAS operations. The need to address runway management is not a new idea; however, as the complexities of factors affecting runway selection and usage increase, the need for effective research in this area correspondingly increases. Under the National Aeronautics and Space Administration s Airspace Systems Program, runway management is a key research area. To address a future NAS which promises to be a complex landscape of factors and competing interests among users and operators, effective runway management strategies and capabilities are required. This effort has evolved from an assessment of current practices, an understanding of research activities addressing surface and airspace operations, traffic flow management enhancements, among others. This work has yielded significant progress. Systems analysis work indicates that the value of System Oriented Runway Management tools is significantly increased in the metroplex environment over that of the single airport case. Algorithms have been developed to provide runway configuration recommendations for a single airport with multiple runways. A benefits analysis has been conducted that indicates the SORM benefits include supporting traffic growth, cost reduction as a result of system efficiency, NAS optimization from metroplex operations, fairness in aircraft operations, and rational decision making

General practitioners\u27 knowledge and approach to chronic kidney disease in Karachi, Pakistan

Due to lack of adequate number of formally trained nephrologists, many patients with chronic kidney disease (CKD) are seen by general practitioners (GPs). This study was designed to assess the knowledge of the GPs regarding identification of CKD and its risk factors, and evaluation and management of risk factors as well as complications of CKD. We conducted a cross-sectional survey of 232 randomly selected GPs from Karachi during 2011. Data were collected on a structured questionnaire based on the kidney disease outcomes and quality initiative recommendations on screening, diagnosis, and management of CKD. A total of 235 GPs were approached, and 232 consented to participate. Mean age was 38.5 ± 11.26 years; 56.5% were men. Most of the GPs knew the traditional risk factors for CKD, i.e., diabetes (88.4%) and hypertension (80%), but were less aware of other risk factors. Only 38% GPs were aware of estimated glomerular filtration rate in evaluation of patients with CKD. Only 61.6% GPs recognized CKD as a risk factor for cardiovascular disease. About 40% and 29% GPs knew the correct goal systolic and diastolic blood pressure, respectively. In all, 41% GPs did not know when to refer the patient to a nephrologist. Our survey identified specific gaps in knowledge and approach of GPs regarding diagnosis and management of CKD. Educational efforts are needed to increase awareness of clinical practice guidelines and recommendations for patients with CKD among GPs, which may improve management and clinical outcomes of this population

Evaluation of Metal Building System Seismic Response Modification Coefficients

NBM ReportA seismic evaluation was conducted of common metal building configurations within the probabilistic framework defined in FEMA P695 “Quantification of Building Seismic Performance Parameters” with the goal of evaluating the applicability of current seismic design procedures in the ASCE 7-10 “Minimum Design Loads for Buildings and Other Structures”. The evaluation began with the definition of a performance group of index archetypes which was guided by industry steering group-led design studies that explored the influence of seismic load combinations and geographical location on the primary frame design. It was observed that taller, shorter span buildings in the western U.S. were most sensitive to seismic demands. This led to the definition of a performance group covering a range of natural periods and seismic weights designed to ASCE Seismic Category D and with the seismic response modification factor of ​R​=3.5. The seismic parameters calculated for the performance group, designed by industry with ASCE Equivalent Lateral Force procedures, were the system overstrength, ductility, and probability of system collapse when exposed to the Maximum Considered Earthquake (MCE) which has a 2% probability of exceedance in 50 years. The system overstrength and ductility for each index archetype were calculated with simulated experiments using thin shell high fidelity simulation, where all metal building components were modeled including the built-up primary frames, the girts and purlins, the exterior metal facade and screw down roof, the rod bracing, and the primary frame flange braces that are important for controlling lateral-torsional buckling. The high fidelity simulation protocol was extensively validated with research between 2006 and 2013 that included monotonic and cyclic primary frame subassembly tests and shake table tests at the University of California, San Diego. The simulated pushover experiments revealed significant system overstrength in the index archetypes and a post-peak ductile response that was sensitive to the controlling limit state. When primary frame lateral-torsional buckling was controlled by the intermediate flange braces, post-peak deformation was available out to large drifts. Panel zone buckling at the knee of the column/rafter resulted in steady post-peak strength degradation. The heavy wall buildings had a higher pushover strength than the light wall buildings because the seismic design load combinations were more influential on the heavy wall primary frame design. The same high fidelity models were used to characterize the quasi-static cyclic response for each index archetype using an accepted American Institute for Steel Construction (AISC) industry loading protocol. The cyclic response, including strength and stiffness degradation from local and global buckling and column-rafter knee panel zone tension field yielding, was fit to a nonlinear Single-Degree-of Freedom (SDOF) material model used for incremental dynamic analysis (IDA). The IDA performances from 44 far-field ground motions required by FEMA P695 led to a cumulative distribution function of spectral intensity of the far-field record set which could be used to calculate the median collapse probability for each index archetype. 4 Uncontrolled collapse was never observed for these light buildings in the simulations or the shake table experiments, however fracture was, in the knee-rafter panel zone from shear buckling and in the rafter taper joints after lateral-torsional buckling. Both drift and fracture studies were conducted to settle on a drift-based collapse limit of 4.5% for the performance group. The collapse margin ratio, defined as the spectral acceleration at median collapse probability to the spectral acceleration from the Maximum Considered Earthquake (MCE) was on average across the metal building performance group higher than the acceptable collapse margin ratio corresponding to a 10% collapse probability, with no outliers greater than 20%. This confirms the viability of the existing ASCE 7 equivalent lateral force seismic design procedures for metal buildings in the performance group considered. With the seismic evaluation process now established and validated, the metal building industry can now investigate other performance groups with potentially large commercial impact - for example, heavier roof buildings that are outside the limits of current ASCE 7 procedures. A modular metal building seismic performance group also becomes available for study with the verified high fidelity modeling protocol used to perform simulated pushover experiments and to quantify cyclic performance.Metal Building Manufacturers Associatio

Experimental Tests on Stability of Cylindrical Shells Under Combined Bending and Torsion

Cylindrical shells with large diameter-to-thickness ratios (normally around 180) are widely used in wind turbine towers. Stability of these thin-walled shell structures is an essential concern, along with cross-section actions on wind turbine towers involving interactions of compression, bending, shear, and torsion arising from both environmental and operational load case conditions. While bending dominates at the base of the tower, combined bending and torsion are commonly the dominant actions in the upper tower segments. Though there have been extensive studies on the stability and design of cylinders subjected to isolated loading conditions (i.e. uniform compression or bending), investigations into the structural response of thin-walled cylinders under combined bending and torsion have been limited. To address the knowledge gap, an experimental study was carried out on cylinders under combined bending and torsion. A total of 48 cylinders were tested with varying diameter-to-thickness ratios and bending-to-torsion ratios comparable to ratios found in wind turbine towers. The relatively high diameter-to-thickness ratios of wind turbine towers mean they are potentially highly imperfection sensitive. To gain further insight into the imperfection sensitivity of cylindrical shells under combined bending and torsion, a laser scanner was used to measure geometric imperfections of each test specimen. The test setup, instrumentation, loading procedures and structural response of cylinders, including ultimate resistances, load-deformation characteristics and failure modes are reported for the first series of tests. Experiments are still being conducted at the time of writing this paper, so only one set of tubes is reported in detail. The test results are aimed to provide a firm basis for the validation of numerical models and advanced design approaches, such as Reference Resistance Design, for cylindrical shells under combined bending and torsion. Future work will involve creating laboratory scale and full scale wind turbine tower finite element models and providing improved guidance on combined bending and torsion demands.This material is based upon work supported by the Na- tional Science Foundation under Grant No. 1912481 and No. 1912354. Any opinions, findings, and conclusions or recom- mendations expressed in this material are those of the au- thors and do not necessarily reflect the views of the National Science Foundation

Presence of multiple coronary angiographic characteristics for the diagnosis of acute coronary thrombus

Background: Coronary angiography is frequently employed to aid in the diagnosis of acute coronary thrombosis, but there is limited data to support its efficacy. The aim of the study was to evaluate sensitivity and specificity of five commonly used angiographic characteristics for diagnosis of acute coronary thrombosis: Ambrose complex lesion morphology; spherical, ovoid, or irregular filling defect; abrupt vessel cutoff; intraluminal staining; and any coronary filling defect. Methods: Coronary angiography of 80 acute myocardial infarction or stable coronary artery disease subjects were assessed in blinded fashion, for the presence or absence of five angiographic characteristics. Only lesions of ≥ 10% stenosis were included in the analysis. Presence or absence of each angiographic characteristic was compared between lesions with or without the following study defined outcomes: 1) histologically confirmed thrombus, 2) highly probable thrombus, and 3) highly unlikely thrombus. Results: A total of 323 lesions were evaluated. All studied angiographic characteristics were associated with histologically confirmed and highly probable thrombotic lesions vs. lesions not meeting criteria for these outcomes (p < 0.03), except for complex Ambrose morphology which was not associated with any of the study outcomes (p > 0.05). Specificity for identifying histologically confirmed or highly probable thrombotic lesion was high (92–100%), especially for spherical, ovoid, or irregular filling defect (99–100%) and intraluminal staining (99%). Sensitivity for identification of histologically confirmed or highly probable thrombotic lesions was low for all tested angiographic characteristics (17–60%). Conclusions: The presence of spherical, ovoid, or irregular filling defect or intraluminal staining was highly suggestive of coronary thrombus. However, none of the evaluated angiographic characteristics were useful for ruling out the presence of coronary thrombus. If confirmed in an independent cohort, these angiographic characteristic will be of significant value in confirming the diagnosis of acute coronary thrombosis.

First-principles modeling of the polycyclic aromatic hydrocarbons reduction

Density functional theory modelling of the reduction of realistic nanographene molecules (C42H18, C48H18 and C60H24) by molecular hydrogen evidences for the presence of limits in the hydrogenation process. These limits caused the contentions between three-fold symmetry of polycyclic aromatic hydrocarbon molecules and two-fold symmetry of adsorbed hydrogen pairs. Increase of the binding energy between nanographenes during reduction is also discussed as possible cause of the experimentally observed limited hydrogenation of studied nanographenes.Comment: 18 pages, 7 figures, accepted to J. Phys. Chem.