Molecular Characterization and Computational Modelling of New Delhi Metallo-ß-Lactamase-5 from an Escherichia coli Isolate (KOEC3) of Bovine Origin.

Emergence of antimicrobial resistance mediated through New Delhi metallo-ß-lactamases (NDMs) is a serious therapeutic challenge. Till date, 16 different NDMs have been described. In this study, we report the molecular and structural characteristics of NDM-5 isolated from an Escherichia coli isolate (KOEC3) of bovine origin. Using PCR amplification, cloning and sequencing of full blaNDM gene, we identified the NDM type as NDM-5. Cloning of full gene in E. coli DH5α and subsequent assessment of antibiotic susceptibility of the transformed cells indicated possible role of native promoter in expression blaNDM-5. Translated amino acid sequence had two substitutions (Val88Leu and Met154Leu) compared to NDM-1. Theoretically deduced isoelectric pH of NDM-5 was 5.88 and instability index was 36.99, indicating a stable protein. From the amino acids sequence, a 3D model of the protein was computed. Analysis of the protein structure elucidated zinc coordination and also revealed a large binding cleft and flexible nature of the protein, which might be the reason for broad substrate range. Docking experiments revealed plausible binding poses for five carbapenem drugs in the vicinity of metal ions. In conclusion, results provided possible explanation for wide range of antibiotics catalyzed by NDM-5 and likely interaction modes with five carbapenem drugs.

Hall and field-effect mobilities in few layered p-WSe2 field-effect transistors.

Here, we present a temperature (T) dependent comparison between field-effect and Hall mobilities in field-effect transistors based on few-layered WSe2 exfoliated onto SiO2. Without dielectric engineering and beyond a T-dependent threshold gate-voltage, we observe maximum hole mobilities approaching 350 cm(2)/Vs at T = 300 K. The hole Hall mobility reaches a maximum value of 650 cm(2)/Vs as T is lowered below ~150 K, indicating that insofar WSe2-based field-effect transistors (FETs) display the largest Hall mobilities among the transition metal dichalcogenides. The gate capacitance, as extracted from the Hall-effect, reveals the presence of spurious charges in the channel, while the two-terminal sheet resistivity displays two-dimensional variable-range hopping behavior, indicating carrier localization induced by disorder at the interface between WSe2 and SiO2. We argue that improvements in the fabrication protocols as, for example, the use of a substrate free of dangling bonds are likely to produce WSe2-based FETs displaying higher room temperature mobilities, i.e. approaching those of p-doped Si, which would make it a suitable candidate for high performance opto-electronics.

New first order Raman-active modes in few layered transition metal dichalcogenides.

Although the main Raman features of semiconducting transition metal dichalcogenides are well known for the monolayer and bulk, there are important differences exhibited by few layered systems which have not been fully addressed. WSe2 samples were synthesized and ab-initio calculations carried out. We calculated phonon dispersions and Raman-active modes in layered systems: WSe2, MoSe2, WS2 and MoS2 ranging from monolayers to five-layers and the bulk. First, we confirmed that as the number of layers increase, the E', E″ and E2g modes shift to lower frequencies, and the A'1 and A1g modes shift to higher frequencies. Second, new high frequency first order A'1 and A1g modes appear, explaining recently reported experimental data for WSe2, MoSe2 and MoS2. Third, splitting of modes around A'1 and A1g is found which explains those observed in MoSe2. Finally, exterior and interior layers possess different vibrational frequencies. Therefore, it is now possible to precisely identify few-layered STMD.

Detection of New Delhi metallo-beta-lactamase and extended-spectrum beta-lactamase genes in Escherichia coli isolated from mastitic milk samples.

In this study, eight Escherichia coli isolates were obtained from milk samples of dairy cattle suffering from clinical/subclinical mastitis. Isolates were characterized for antimicrobial resistance traits and virulence genes. Results revealed that one isolate was harbouring New Delhi metallo-beta-lactamase gene (blaNDM ). Cloning and sequencing of the PCR amplicon confirmed the identity of the gene (GenBank accession no. KC769583) having 100% homology with blaNDM-5 (GenBank accession no. JN104597.1), and this isolate was susceptible to colistin, chloramphenicol and tetracycline only. Moreover, another isolate carried extended-spectrum beta-lactamase (ESBL) gene - blaCTX-M , and all isolates possessed blaTEM gene. Of the eight isolates, only one isolate was positive for shiga toxin gene (stx2), and none were harbouring stx1 gene. Occurrence of New Delhi metallo-beta-lactamase (blaNDM ) in one E. coli isolate and ESBL genes in other isolates poses a potential threat to human health following possible entry and spread through food chain.

Switching of ± 360° domain wall states in a nanoring by an azimuthal Oersted field.

We demonstrate magnetic switching between two 360° domain wall vortex states in cobalt nanorings, which are candidate magnetic states for robust and low power magnetoresistive random access memory (MRAM) devices. These 360° domain wall (DW) or 'twisted onion' states can have clockwise or counterclockwise circulation, the two states for data storage. Reliable switching between the states is necessary for any realistic device. We accomplish this switching by applying a circular Oersted field created by passing current through a metal atomic force microscope tip placed at the center of the ring. After initializing in an onion state, we rotate the DWs to one side of the ring by passing a current through the center, and can switch between the two twisted states by reversing the current, causing the DWs to split and meet again on the opposite side of the ring. A larger current will annihilate the DWs and create a perfect vortex state in the rings.

The specific heat and effective thermal conductivity of composites containing single-wall and multi-wall carbon nanotubes.

We present a study of the specific heat and effective thermal conductivity in anisotropic and randomly oriented multi-wall carbon nanotube (MWCNT) and randomly oriented single-wall carbon nanotube (SWCNT) composites from 300 to 400 K. Measurements on randomly oriented MWCNTs and SWCNTs were made by depositing a thin film of CNTs within a calorimetric cell. Anisotropic measurements were made on MWCNTs grown inside the highly ordered, densely packed nanochannels of anodic aluminum oxide. The specific heat of randomly oriented MWCNTs and SWCNTs showed similar behavior to the specific heat of bulk graphite powder. However, the specific heat of aligned MWCNTs is smaller and has weaker temperature dependence than that of the bulk above room temperature. The effective thermal conductivity of randomly oriented MWCNTs and SWCNTs is similar to that of powder graphite, exhibiting a maximum value near 364 K indicating the onset of phonon-phonon scattering. The effective thermal conductivity of the anisotropic MWCNTs increased smoothly with increasing temperature and is indicative of the one-dimensional nature of the heat flow.

Tuberculous aneurysm of extracranial carotid artery.

Incidence of extracranial carotid aneurysm is rare and represents a challenge to treatment strategy. Two patients presented to us a couple of years apart with pulsatile neck swellings. We propose that the extracranial carotid artery pseudoaneurysm was as a result of direct extension from tuberculous lymphadenitis and discuss the management of these patients.

Specific heat and thermal conductivity measurements for anisotropic and random macroscopic composites of cobalt nanowires.

We report simultaneous specific heat (c(p)) and thermal conductivity (κ) measurements for anisotropic and random macroscopic composites of cobalt nanowires (Co NWs), from 300 to 400 K. Anisotropic composites of Co NW consist of nanowires grown within the highly ordered, densely packed array of parallel nanochannels in anodized aluminum oxide. Random composites are formed by drop-casting a thin film of randomly oriented Co NWs, removed from the anodized aluminum oxide host, within a calorimetric cell. The specific heat measured with the heat flow parallel to the Co NW alignment ([Formula: see text]) and that for the random sample (c(p)(R)) deviate strongly in temperature dependence from that measured for bulk, amorphous, powder cobalt under identical experimental conditions. The thermal conductivity for random composites (κ(R)) follows a bulk-like behavior though it is greatly reduced in magnitude, exhibiting a broad maximum near 365 K indicating the onset of boundary-phonon scattering. The thermal conductivity in the anisotropic sample ([Formula: see text]) is equally reduced in magnitude but increases smoothly with increasing temperature and appears to be dominated by phonon-phonon scattering.

Survivorship analysis of 3234 primary knee arthroplasties implanted over a 26-year period: a study of eight different implant designs.

We conducted a survivorship analysis of 3234 primary total knee replacements performed at our hospital between 1969 and 1995. Each knee replacement was entered once only. Revision was defined as the end point. Data were collected both from patient records and by postal questionnaire. Eight types of knee prostheses were evaluated with best-case and worst-case scenarios compared over a 5-, 10- and 15-year period. The evidence suggests that the "Condylar type devices" which include the Total Condylar, Press Fit Condylar (PFC), Kinematic, Kinemax and Anatomic Modular Knee (AMK) have very similar survivorship curves and in the main have performed well up to a 10-year period. The LCS mobile bearing knee performed well at 5 years. The earlier design prostheses had a poor result in terms of survivorship and are hence were discontinued.

Salvage revision total knee replacement using the Endo-Model rotating hinge prosthesis.

Inability to balance a knee in complex revision total knee replacement has led to the use of rotating hinged knee devices in these cases as a salvage procedure. We conducted a retrospective study of 50 patients receiving 51 Endo-Model rotating hinge prosthesis with an average follow-up of 4 years (range 2-6 years). Clinical and radiological results were reviewed at latest follow-up. Five patients died from unrelated causes. Reasons for revision were infection (23), aseptic loosening (23), implant failure (3), stiffness (1) and peri-prosthetic fracture (1). The average number of previous surgery from and including the primary arthroplasty was three (ranges 1-14). Seven patients required plastic surgery for soft tissue cover. There was notable improvement in the pain, stability, range of motion and mobility of the patients with an improvement in the Hospital for Special Surgery Score (35.9 to 72.17). Postoperatively, 11 (22%) had an excellent HSS grade, 22 (44%) good grade, 10 (19%) fair grade and 8 (15%) poor grade. A significant number of our patients had an extremely low preoperative HSS score, and for these patients, an improvement to a fair grade HSS score was a satisfactory and realistic outcome. Forty-four (86%) patients were satisfied with the outcome of the revision surgery, 3 (6%) noncommittal and 4 (8%) disappointed. Comparing revision for infection vs. aseptic loosening, 22 (95%) patients out of 23 were satisfied in the aseptic loosening group vs. 17 (74%) out of 23 were satisfied in the infected group. In selected complex cases, salvage revision surgery shows encouraging results in the short to medium term using the Endo-Model rotating hinge prosthesis. A knee score such as the Hospital for Special Surgery score (objective outcome) should be used in conjunction with a patient satisfaction questionnaire (subjective outcome) in assessing the clinical outcome of complex, salvage revision knee surgery. Revision for infected total knee replacement is less likely to produce a satisfactory outcome as compared to revision for aseptic loosening.

Demodicidosis in livestock in West Bengal (India).

Of 2820 livestock, comprising 472 cattle, 294 goats, 128 pigs and 665 dogs of urban and rural areas of West Bengal (India), 89 (3.15%) were found to suffer from demodicidosis. Highest infestation rate (3.87%) was observed in dogs followed by cattle (3.11%), goats (2.44%) and pigs (1.44%). The infestation rate did not differ significantly between urban and rural areas. Head, neck and face were the common sites of lesions followed by extremities and body surfaces. Females were infested more than males. Animals of all age groups suffered from mange infestation, though highest infestation (18.00%) was observed in 36-47 months of age and lowest (10.11%) in 72 months and above age groups. Some bacterial invaders were isolated from the demodectic lesions, which were found sensitive to a number of common antibiotics. Fungi like Trichophyton mentagrophytes could also be isolated from the lesions.