Evaluating the in vitro susceptibility of bovine mastitis pathogens to a combination of kanamycin and cefalexin: Recommendations for a disk diffusion test

Cows suffering from bovine mastitis have markedly reduced milk production because of inflammation within the udder subsequent to infection and damage from bacterial toxins. Antibiotic treatment is commonly used as a preventative and therapeutic measure for bovine mastitis. The most common pathogens include Staphylococcus aureus, various streptococci (Streptococcus dysgalactiae, Streptococcus uberis), and coliforms (Escherichia coli), which can be contracted from other infected cows or from the environment. A combination of kanamycin and cefalexin (1:1.5 wt/wt) is currently used therapeutically in Europe for the treatment of bovine mastitis, although standardized methods for the in vitro determination of the susceptibility of target pathogens have not been developed. This study evaluates the appropriate broth microdilution testing criteria for kanamycin and cefalexin administered in combination and reports the development of a disk diffusion test. At a ratio of kanamycin:cefalexin relevant to that observed in milk postadministration (10:1 wt/wt), the minimum inhibitory concentrations were determined against 307 isolates of target mastitis pathogens (staphylococci, streptococci, and E. coli). Based on achievable concentrations in milk and the resulting distribution of minimum inhibitory concentrations, preliminary broth breakpoints for kanamycin/cefalexin (10:1 fixed ratio) of ≤8/0.8 μg/mL susceptible, 16/1.6 μg/mL intermediate, and ≥32/3.2 μg/mL resistant were applied to evaluated staphylococci, streptococci, and E. coli. Parallel testing by disk diffusion and resulting error-rate bounded analysis using a combined disk concentration of 30 μg of kanamycin and 15 μg of cefalexin resulted in the establishment of preliminary disk interpretive breakpoints of ≥20 mm susceptible, 18 to 19 mm intermediate, and ≤17 mm resistant for staphylococci, streptococci (Strep. uberis and Strep. dysgalactiae only), and E. coli.     

O fly,where art thou?

In this paper, the design of a real-time image acquisition system for tracking the movement of Drosophila in three-dimensional space is presented. The system uses three calibrated and synchronized cameras to detect multiple flies and integrates the detected fly silhouettes to construct the three-dimensional visual hull models of each fly. We used an extended Kalman filter to estimate the state of each fly, given past positions from the reconstructed fly visual hulls. The results show that our approach constructs the three-dimensional visual hull of each fly from the detected image silhouettes and robustly tracks them at real-time rates. The system is suitable for a more detailed analysis of fly behaviour.     

An experimental study of wireless connectivity and routing in ad hoc sensor networks for real-time soccer player monitoring

Live physiological monitoring of soccer players during sporting events can help maximise athlete performance while preventing injury, and enable new applications for referee-assist and enhanced television broadcast services. However, the harsh operating conditions in the soccer field pose several challenges: (a) body-mounted wireless sensor devices have limited radio range, (b) playing area is large, necessitating multi-hop transmission, (c) wireless connectivity is dynamic due to extreme mobility, and (d) data forwarding has to operate within tight delay/energy constraints. In this paper, we take a first step towards characterising wireless connectivity in the soccer field by undertaking experimental work with local soccer clubs, and assess the feasibility of real-time athlete monitoring. We make three specific contributions: (1) We develop an empirical profile of radio signal strength in an open soccer field taking into account distance and body orientation of the athlete. (2) Using data from several soccer games we profile key characteristics of wireless connectivity, highlighting aspects such as small power-law inter-encounters and link correlations. (3) We develop practical multi-hop routing algorithms that can be tuned to achieve the right balance between the competing objectives of resource consumption and data extraction delay. We believe our study is the first to characterise the wireless environment for mobile sensor networks in field sports, and paves the way towards realisation of real-time athlete monitoring systems.     

A calcium phosphate cryogel for alkaline phosphatase encapsulation

There has been significant interest in the development of biomaterials that can localise drugs, enzymes and other therapeutic molecules and be well tolerated in the body. To date, the majority of research in this area has focussed on the formulation and refinement of silica-based gels. Whilst significant progress has been made in optimising silica gel materials, their manufacture typically requires the use of toxic precursors. Here we report the encapsulation of alkaline phosphatase (ALP) in a calcium phosphate-based cryogel. The activity of the ALP following encapsulation, over a period of 14 days, was evaluated and compared with the activity of horseradish peroxidise (HRP), a model enzyme often used in encapsulation studies. Furthermore, the chemical and structural properties exhibited by the gel were determined using X-ray diffraction, helium pycnometry and mercury porosimetry. It was found that when encapsulated in the gel, the activity of ALP was preserved and remained higher than when aged for an equivalent amount of time free in solution. In the case of HRP, however, encapsulation reduced enzyme activity. This was attributed to the different sizes and charges exhibited by the substrates of these two enzymes and the associated diffusional limitations through the mesopores of the gel structure.     

A digraph approach to TQM evaluation of an industry

Different total quality management (TQM) environments may be suggested to an organization for improving the quality of products, customer satisfaction, competitiveness and profitability by TQM experts. This paper identifies factors responsible for the TQM environment. All these factors are interacting with each other by different amounts. An attempt has been made to develop a mathematical model of the TQM environment from these interacting factors using a graph theoretic approach. In the graph theoretic model, a directed graph or digraph is used to represent abstract information of the system using directed edges, which is useful for visual analysis. The matrix model developed from the digraph is useful for computer processing. A permanent value of multinomial developed from the matrix represents the environment uniquely by a single number/index, which is useful for comparison, ranking and optimum selection. The method is quite flexible to accommodate new factors and market dynamics in global business in a bid to go for continuous improvement and breakthrough improvement in the environment, product, process and intellectual property rights (IPR).     

Percolation dominated electron transport in Tetracyanoquinodimethane mixed 4,7-diphenyl-1,10-phenanthroline thin films

Highly conducting and electron transporting organic semiconductor tetracyano-quinodimethane (TCNQ) has been added to the well known electron transporting material 4,7-diphenyl-1,10-phenanthroline (BPhen) in various mixing percentages. Electron only devices exhibited a distinctive transition from low to high conductivity. The results have been found to be in good agreement with classical percolation theory with a percolation threshold of 3.8 wt.% and a critical exponent value of 1.3. This demonstrates the formation of a morphologically stable 2D percolating network that has been supported by AFM analysis. The composition thus formed indicates a promising electron injecting material for optoelectronic devices.     

Selective interfacial localization in conducting polycaprolactam/ethylene vinyl acetate/carbon black composites

Unusual electrical conductivity was demonstrated by ethylene vinyl acetate/polycaprolactam/carbon black (CB) composites. The critical exponent value was 1.2 ± 0.2 for ternary composites and was greater than 2.0 for the binary composites, indicating two‐dimensional electrical conduction in ternary composites. The ternary composites also showed inverted U‐shaped conductivity curves when CB weight fraction was greater than 10 wt%. However, at 10 wt% CB, a discontinuous conductivity curve showing conductivity only when polycaprolactam content was greater than 50% was observed, suggesting substantial variation in the interfacial characteristics with the change in the blend composition. Small‐angle X‐ray scattering studies pointed out that ternary composites can be viewed as a two‐phase system with sharp boundaries, and that interface layer in the composites does not exist. Differential scanning calorimetry studies suggested composition dependent variation in the crystallinity of polycaprolactam phase, partially contributing to the increase in the composites' conductivity at higher polycaprolactam fractions. POLYM. COMPOS., 34:912–919, 2013. © 2013 Society of Plastics Engineers     

Molecular Cloning and Sequence Analysis of Bile Salt Hydrolase Gene (bsh) from Lactobacillus plantarum MBUL90 Strain of Human Origin

This study provided genetic information on a bile salt hydrolase (bsh) of a Lactobacillus plantarum strain of Indian origin, MBUL90. L. plantarum strains were screened by PCR for the determination of the bsh locus in their genome using specific primers. None of the lactobacilli strains produced the expected size of amplicon (～ 1.0 kb) except L. plantarum strains, which proved the specificity of the primers. The bsh amplicon of L. plantarum MBUL90 was cloned into pDrive vector, and nucleotide sequences were determined. Sequence analysis of bsh genes revealed a high level of similarity within the species of L. plantarum as well as with other species of Lactobacillus. The resulting nucleotide sequence of an ORF of 975 bp encoded a predicted protein of 324 amino acids representing a theoretical molecular mass of 37 kDa with a pI of 4.92. The protein deduced from the complete ORF had high similarity with other Bsh proteins, and four highly conserved amino acid motifs (YFGRNXD, NEXGLXXAGLNF, VXVLTNNPXF, and SXSRFVRXAF) were located around the active site. Genetic data presented in this paper provide a sound foundation for better understanding the genetic diversity of bsh in Lactobacillus genus and may provide a new genetic marker for phylogenetic study.