Biomedical subjects

Victor Morris

Publications and source records attributed to Victor Morris.

3 recordsLinked to original sources

PubMed2004

Synergistic interactions between the genetically modified bacterial polysaccharide P2 and carob or konjac mannan.

Rheological studies have confirmed that the bacterial polysaccharide P2, a genetically modified variant of the Acetobacter xylinum polysaccharide acetan, undergoes synergistic gelation with either of the plant polysaccharides carob or konjac mannan. X-ray fibre diffraction data shows that P2 can form a 5-fold helical structure of pitch 4.7nm and an axial rise per disaccharide repeat of 0.92nm. Optical rotation data demonstrate that P2 undergoes a coil-helix transition in solution and that deacylation enhances the stability of the helical structure in solution. Studies made on mixtures prepared at different temperatures and ionic strengths suggest that denaturation of the P2 helix favours interaction and gelation. Deacetylation of P2 enhances gelation. X-ray diffraction data for oriented fibres prepared from deacetylated P2-konjac mannan mixed films reveal a 6-fold helical structure of pitch 5.54nm with an axial rise per disaccharide repeat also of 0.92nm. This mixed helix provides direct evidence for binding between the two polysaccharides. P2 contains two sites of acetylation: one on the backbone and one on the sidechain. The former site of acetylation inhibits helix formation for P2. It is suggested that this site of acetylation also inhibits formation of the mixed helix, explaining the enhanced gelation of mixtures on deacetylation.

Amorphophallus↗

PubMed2004

Proteins and emulsifiers at liquid interfaces.

The interfacial properties of proteins and emulsifiers have been studied extensively in the field of food colloid research. Emulsions form the basis of a huge range of food products and are generally stabilised by either protein and/or emulsifiers. Proteins have been shown to stabilise emulsions by forming a viscoelastic, adsorbed layer on the oil droplets, which form a physical barrier to coalescence. Emulsifiers can be oil or water soluble, forming a fluid, close-packed layer at the interface with a low interfacial tension. This results in an emulsion with a small droplet size distribution, stabilised by the fluid Gibbs-Marangoni mechanism or weak electrostatic repulsion. In real food emulsions, there is usually a mixture of proteins and emulsifiers competing for the interfacial area. This can produce a finer emulsion, however, the emulsifiers break down the viscoelastic protein-adsorbed layer, resulting in an emulsion with reduced stability. We present a review recent work that aims to characterise the composition, structure and physical properties of mixed protein-emulsifier interfaces, in an effort to understand the mechanisms behind the stability behaviour of food emulsion systems.

Colloids↗

PubMedDate not supplied

Prevention of nosocomial catheter-associated urinary tract infections through computerized feedback to physicians and a nurse-directed protocol.

Catheter-associated urinary tract infections (CAUTIs) represent the most common nosocomial infection. The authors' baseline rate of CAUTI for general medical service was elevated at 36 per 1000 catheter-days. The medical literature has consistently linked inappropriate catheter use with the development of CAUTI. The baseline data also revealed a high rate of inappropriate use of indwelling urinary catheters. Using the dual modalities of technology through prompts in the computerized order/entry system and handheld bladder scanners, as well as in combination with staff education and nurse empowerment, the authors were successful in reducing the use and duration of urinary catheters as well as the incidence of CAUTI. In subsequent data collection cycles over the following 2 years, 81% reduction in device use and a 73% reduction in the clinical end point of nosocomial CAUTI (36/1000 catheter-days to 11/1000 catheter-days; P < .001) was demonstrated.

Aged↗