BackgroundThe increasing and rapid spread of metallo-beta-lactamase (MBL) producing Enterobacteriaceae, particularly Escherichia coli and Klebsiella pneumoniae represents an emerging public health threat. However, limited data is available on MBL production in clinical isolates of E. coli and K. pneumoniae from Nepal. We have therefore undertaken this study to ascertain the incidence of MBL production in clinical isolates of E. coli and K. pneumoniae at a tertiary care teaching hospital in central Nepal.MethodsA total of 401 consecutive, non-duplicate isolates of E. coli (n = 216) and K. pneumoniae (n = 185) were recovered from various clinical samples between July and December, 2012. These isolates were screened for the detection of carbapenemase production on the basis of their reduced susceptibility to meropenem or ertapenem by the disc diffusion method. The screened isolates were further phenotypically studied for carbapenemase production by modified Hodge test (MHT). MBL production was detected by performing combined disc test by using imipenem discs with and without ethylenediaminetetraacetic acid (EDTA), which chelates zinc required for MBL activity.ResultsOut of 216 E. coli isolates, a total of 41 isolates (18.98%) and out of 185 K. pneumoniae isolates, a total of 39 isolates (21.08%) were suspected to be carbapenemase- producers on the basis of their reduced susceptibility to meropenem or ertapenem. Interestingly, all the initially suspected isolates of E. coli and K. pneumoniae for carbapenemase production were found to be positive in both MHT and combined disc test. However, few weakly positive reactions were observed in MHT. All the MBL producing isolates were multidrug-resistant (MDR). In addition, 75.60% E. coli and 71.79% of K. pneumoniae isolates producing MBL were found to be “pandrug- resistant”.ConclusionsOur findings showed MBL production in a considerable number of E. coli and K. pneumoniae isolates with MDR and pandrug-resistant phenotypes. Combined disc method can provide a sensible choice for phenotypic detection of MBL production in clinical microbiology laboratories as detection of MBL in bacterial isolates is indispensable for establishing the effective antibiotic policies and infection control strategies in the hospital setting.

Astrocyte plays a pivotal role in synaptic transmission with neuron. It maintains the ionic concentration in synapse to regulate signals from one cell to another. Calcium known as second messenger plays an important role in signal transduction. There are so many physiological processes that affect the cytosolic calcium concentration [ Ca 2+]i like calcium buffering, flow of calcium ion through channels, etc. The modeling of calcium signaling in astrocytes has become more sophisticated. The modeling effort has provided insight to understand the cell contraction. Main objective of this work is to study the effect of voltage-gated calcium channel on calcium profile under excess buffer approximation in the form of diffusion equation. A mathematical model is developed in the form of diffusion equation for the calcium profile. The model incorporates the important physiological parameter like diffusion coefficient association rate constant, etc. Appropriate boundary conditions have been framed. Finite element method is employed to solve the problem. A MATLAB program has been developed for the entire problem and simulated to compute the numerical results.

As we enter the new millennium, manufacturers of laundry detergents would like to provide new products for the twenty-first century. With the goal of achieving new and better performance characteristics, design strategies for research and development should be defined. This paper highlights the importance of micellar relaxation kinetics in processes involved in detergency. Earlier Shah and coworkers showed that the stability of sodium dodecyl sulfate (SDS) micelles plays an important role in various technological processes. The slow relaxation time (τ 2 ) of SDS micelles, as measured by the pressure-jump technique, was in the range of 10 −4 to 10 1 s, depending on the surfactant concentration. A maximal relaxation time and thus a maximal micellar stability was found at 200 mM SDS (5 s), corresponding to the least-foaming, largest bubble size, longest wetting time of textile, largest emulsion droplet size, and the most rapid solubilization of oil. These results are explained in terms of the flux of surfactant monomers from the bulk to the interface, which determines the dynamic surface tension. More stable micelles lead to less monomer flux and hence to a higher dynamic surface tension. The relaxation time for nonionic surfactants (as measured by the stopped-flow technique) was much longer than for ionic surfactants because of the absence of ionic repulsion between the head groups. The τ 2 was related to dynamic surface-tension experiments. Stability of SDS micelles can be greatly enhanced by the addition of long-chain alcohols or cationic surfactants. In summary, relaxation time data of surfactant solutions enable us to predict the performance of a given surfactant solution. Moreover, results suggest that one can design appropriate micelles with specific stability, or τ 2 , by controlling surfactant structure, concentration, and physicochemical conditions, as well as by mixing anionic/cationic or ionic/nonionic surfactants for a desired technological application, e.g., detergency.Paper no. S1115 in JSD 2, 317-324 (July 1999). FIG. 1. Schematic representation of the three environments in which surfactant molecules reside in water. FIG. 2. Mechanisms for the two relaxation times, τ 1 and τ 2 , for a surfactant solution above critical micelle concentration (CMC). FIG. 3. Schematic representation of adsorption of surfactant on the newly created air/water interface during foam generation. FIG. 4. Schematic representation showing the importance of micelle breakup in fabric wetting. FIG. 5. Schematic representation showing the importance of micelle breakup in emulsification. 320 A. PATIST ET AL. FIG. 6. Slow relaxation time, τ 2 , of sodium dodecyl sulfate (SDS) micelles at various surfactant concentrations (CMC = 8.3 mM). See Figure 2 for other abbreviation.

The relationship between the spreading of antifoam oils and their performance is much discussed in the literature, but a demonstrated connection between antifoam spreading and performance has been lacking. This paper reports the performance of a poly(dimethylsiloxane) (PDMS)-based antifoam on foam produced by 12 surfactant solutions. These include single or mixed surfactant systems, including impure surfactant mixtures to model fabric washing detergents. The oil film spreading pressure, πo/w, is presented as a simple and relevant measurement of the thermodynamics of antifoam oil spreading. Antifoaming efficacy was measured as the relative reduction in the initial foam height, ∆Hrel, using cylinder shake tests at a fixed antifoam dosage. ∆Hrel is shown to increase with πo/w, demonstrating a strong statistical correlation between antifoam oil spreading and its performance. Antifoam effectiveness varies with surfactant concentration, surfactant type, and surfactant hydrophobe size and also with increased density of surfactant packing. Surface shear viscosity, µ s , was used to quantify surfactant packing. Antifoam effectiveness decreases with increasing surface shear viscosity. This finding provides a potentially useful link between antifoam efficacy and surfactant selection based on well-established surfactant molecular packing parameters. The role of spreading of antifoam oil at the air/surfactant solution interface is investigated. Oil film spreading pressure is shown to decrease by a power law function with increasing surface shear viscosity of the surfactant film. A new fluorescence technique was used to measure the extent of PDMS spreading. Initial results suggest a correlation between the spreading distance and antifoaming performance. An antifoam mechanism is proposed that features antifoam spreading as a direct contributor to bubble film rupture and incorporates surfactant type and concentration, surfactant packing density, and antifoam oil film spreading pressure as factors contributing to antifoam efficacy.