The genetic and biochemical basis of ampicillin resistance amongst the aerobic Gram-negative commensal faecal flora of healthy volunteers in South Africa has been determined. Amongst 608 ampicillin resistant strains isolated from 320 of the participants, 158 were able to transfer their ampicillin resistant determinants into Escherichia coli K-12 J62-2. Iso-electric focusing of the beta-lactamas...

The origin of myofibroblasts in stromal reaction has been a subject of controversy. To address this question definitively, we developed techniques for purification and characterization of major stromal cell types. We defined a panel of markers that could, in combination, unequivocally distinguish these cell types by immunocytochemistry, iso-electric focusing, immunoblotting, and two-dimensional...

The presynaptic terminal vesicle population of Torpedo electric organ is heterogeneous in size, consisting of two prominent subpopulations that comprise 80% of the total. The use of standard iso-osmotic sucrose gradients with zonal centrifugation to isolate vesicle fractions that co-localize with the acetylcholine (ACh) peak results in the recovery of: (1) 10% of the total estimated vesicle pop...

Membranes are of increasing interest for the removal of human enteric viruses from wastewater, especially when the goal of treatment is reuse. Limited work has been undertaken on fundamental issues such as aggregation and the role of electrostatic and hydrophobic interactions, as opposed to the sieving of viruses by membranes. One apparently critical factor would be the iso-electric point (pI) ...

In an attempt to distinguish between the UDP-glucose: flavonol 3-O-glucosyltransferase (3G T ) and the UDP-glucose:anthocyanidin 3-O-glucosyltransferase in flower buds o f Petunia hybrida, several properties of these activities were determined. The 3-glucosylation o f anthocyanidin had a pH-activity optimum of 7.2, that o f flavonol pH 9.2 to 9.5. Anthocyanidin 3G T activity was lowered in the ...

Protection practices in electric utility industry as it existed prior to re-structuring were designed to meet certain goals of sound engineering principles as they were applied, primarily to component protection in vertically integrated electric utility systems. There has been a significant shift in emphasis from uncomplicated component protection to system protection to avoid or mitigate wide-...

A Lab-On-Chip micro-device has been introduced for the focusing and separation of particles which exploits negative dielectrophoretic (nDEP) force. A 3D numerical computational model was presented to simulate the focusing and separation process. In particular, the model will solve for bioparticle movement and Joule heating. In the experimental study, the mixture of viable and nonviable yeast ce...

This paper describes the theorem proving component of a larger software development environment for the ISO standardized spec-iication language VDM-SL. This component is constructed as an instan-tiation of the generic theorem prover Isabelle with a VDM-SL variant of the Logic of Partial Functions (LPF). We describe the development of this instantiation, focusing on both the embedding of syntax ...

This study was designed to assess the influence of three soil DNA extraction procedures, namely the International Organization for Standardization (ISO-11063, GnS-GII and modified ISO procedure (ISOm), on the taxonomic diversity and composition of soil bacterial and fungal communities. The efficacy of each soil DNA extraction method was assessed on five soils, differing in their physico-chemica...

The security of information systems focuses on raising the level of business security while aligning with its strategy and objectives. The family of ISO 2700x, whose theme is: Information technology Security techniques, allows taking into account all of these security problems, by offering a pack of uniform and standards that respect the continuous improvement cycle PDCA. Being closely linked t...