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Biomedical subjects

J Garside

Publications and source records attributed to J Garside.

12 recordsLinked to original sources
PubMed2006

Microbiological quality of randomly selected ready-to-eat foods sampled between 2003 and 2005 in Wales, UK.

Since 1995, the publicly funded ready-to-eat food sampling and examination activities in Wales have been coordinated and structured, using a novel approach for the identification of samples and premises. The latest set of data from this surveillance system reports the results from 3391 ready-to-eat foods sampled between November 2003 and March 2005. During this seventeen-month period all samples were examined for aerobic colony count, Escherichia coli, Listeria spp., Bacillus cereus, Salmonella, Staphylococcus aureus and Listeria monocytogenes. The food types with the poorest microbiological quality were cream cakes, custard slices and egg mayonnaise sandwiches. The food type with the best microbiological quality was dried fruit. In conclusion, the results indicate that, in general terms, the ready-to-eat food types sampled and examined in this period posed little bacterial hazard to consumers.

Bacillus cereus↗
PubMed1998

Nucleation and growth of microbial lipase crystals from clarified concentrated fermentation broths.

Bulk crystallization is emerging as a new industrial operation for protein recovery. Characterization of bulk protein crystallization is more complex than protein crystallization for structural study where single crystals are grown in flow cells. This is because both nucleation and crystal growth processes are taking place while the supersaturation falls. An algorithm is presented to characterize crystallization using the rates of the two kinetic processes, nucleation and growth. The values of these rates allow ready comparison of the crystallization process under different operating conditions. The crystallization, via adjustment to the isoelectric pH of a fungal lipase from clarified fermentation broth, is described for a batch stirred reactor. A maximum nucleation rate of five to six crystals formed per microliter of suspension per second and a high power dependency ( approximately 11) on the degree of supersaturation were found. The suspended protein crystals were found to grow at a rate of up to 15-20 nm/s and also to exhibit a high power dependency ( approximately 6) of growth rate on the degree of supersaturation.

Crystallization↗
PubMed1993

Crystallization kinetics of calcium oxalate in fresh, minimally diluted urine: comparison of recurrent stone formers and healthy controls in a continuous mixed suspension mixed product removal crystallizer.

A reproducible method has been developed for studying calcium oxalate crystallization from fresh, minimally diluted (92%) urine with the mixed suspension mixed product removal continuous crystallization technique. All samples were adjusted to give the same starting calcium and oxalate concentrations. Twenty-one recurrent male stone formers were compared with twenty-two healthy controls. There was no difference in crystal growth rates but crystal nucleation rates were much higher in the control group (p = 0.003). Using growth rate and nucleation rate results, the amount of crystalline material in suspension was shown to be lower in the urine from stone formers, and therefore the equilibrium supersaturation in the crystallizer was lower in the control group (p = 0.001). We propose that the ability of a healthy person's urine to maintain a lower supersaturation is a crucial protective factor distinguishing non-stone formers from stone formers.

Calcium Oxalate↗
PubMed1990

Calcium oxalate crystallisation kinetics and the effects of calcium and gamma-carboxyglutamic acid.

gamma-carboxyglutamic acid (GLA) is an amino acid with a high affinity for calcium. It is found in urine both as the free amino acid and incorporated into proteins such as osteocalcin. Free and bound GLA have been reported to be found at higher concentrations in the urine of stone formers than controls. We have investigated the effect of GLA and calcium, at physiological levels, on the crystallisation of calcium oxalate using a mixed suspension mixed product removal continuous crystalliser. GLA caused very significant changes in the crystallisation kinetics, but the effect was dependent on the calcium concentration. At 4 mM calcium, GLA decreased the growth rate and increased the nucleation rate; at 12 mM the reverse occurred. At all concentrations of calcium tested, GLA caused a significantly increased crystal mass to be produced. Our evidence supports the hypothesis that GLA modifies calcium oxalate crystallisation and could be a promoter of stone formation in vivo, particularly at moderately elevated levels of calcium excretion.

1-Carboxyglutamic Acid↗
PubMed1989

The effect of glycosaminoglycans on the crystallisation of calcium oxalate.

The effect of glycosaminoglycans on urinary stone formation was evaluated using a mixed suspension, mixed product removal (MSMPR) crystallisation system together with scanning electron microscopy (SEM) to examine the resulting crystals. Chondroitin sulphate was found to decrease the nucleation rate and to promote both the growth rate and suspension density. Results obtained with hyaluronic acid, although inconclusive, are similar to those given by chondroitin sulphate. Heparin sodium salt had a powerful inhibitory effect on both the nucleation rate and the suspension density, the effect increasing in proportion to the heparin concentration. SEM examination showed that the octahedral habit of calcium oxalate dihydrate was modified by the addition of heparin sodium salt and confirmed that the average crystal size in the presence of chondroitin sulphate and hyaluronic acid was significantly greater than the control or that found in the presence of heparin sodium salt.

Calcium Oxalate↗
PubMed1988

The role of magnesium in calcium oxalate urolithiasis.

The aim of this study was to evaluate the effect of magnesium on calcium oxalate crystal formation, both in physiological conditions and at slightly higher oxalate concentrations, using a mixed suspension mixed product removal crystallizer and scanning electron microscopy. True supersaturation ratios were calculated by allowing for complexation in solution. Magnesium inhibited the nucleation rate at all oxalate concentrations. It also inhibited the growth rate at oxalate concentrations of less than approximately 2.0 mmol/l but promoted the growth rate at higher concentrations. This suggests that, provided the oxalate concentration is sufficiently high, increase of magnesium concentration can increase the crystal growth rate. At physiological concentrations of oxalate, however, magnesium decreases both nucleation and growth rates. The SEM photographs showed that the predominant crystal was calcium oxalate trihydrate at low magnesium concentrations, with calcium oxalate dihydrate being observed in larger quantities at high magnesium concentrations.

Calcium Oxalate↗
PubMed1987

Observations on in vitro and in vivo calcium oxalate crystalluria in primary calcium stone formers and normal subjects.

Fresh urine samples from stone formers (SF) and normal subjects (N) were rapidly evaporated at 37 degrees C to 1200 mosmol/kgH2O and the particle size distribution of the formed particles studied by Coulter Counter and chemical methods. No significant difference was found between the two groups in their relative supersaturation of calcium oxalate at the point of spontaneous precipitation. SF and N urines seem to have an equal driving force for particle precipitation. The major difference between them was in the volume of particles with diameters greater than 11.4 microns. SF urines showed an approximately 5-fold increase in total particle volume (after evaporation) and N urines had about a 2-fold increase over the volume in the freshly voided urine samples. The total volume of large particles (greater than 11.4 micron) increased more than 7-fold in SF urine while only a 2-fold increase was detected in the normal urines after evaporation.

Adult↗
PubMed1986

Calcium oxalate precipitation in a flow system: an attempt to simulate the early stages of stone formation in the renal tubules.

This paper describes in vitro studies on the generation of supersaturation and the early stages of calcium oxalate (CaOx) precipitation using a reverse osmosis hollow-fiber membrane to simulate the precipitation processes occurring in the distal convoluted tubule and the collecting system of the kidney. The article reports on the preliminary results of using a plug-flow configuration to simulate the reabsorption of water and generation of supersaturation during the approximately three-minute biological residence time of the urine in the upper part of the urinary tract. The results suggest that microcrystallization of CaOx . 2H2O in the renal tubules may play a role in stone formation processes. A survey of the effect of various inhibitors of CaOx precipitation indicates that pyrophosphate, magnesium, glutamic acid, heparin and citric acid reduce the tendency of CaOx crystals formed to agglomerate in this system.

Calcium Oxalate↗
PubMed1985

Effects of magnesium on calcium oxalate crystallization.

We evaluated the effect of a range of physiological concentrations of magnesium on calcium oxalate crystallization from artificial urine in a continuous mixed suspension mixed product removal crystallizer at 37C. Magnesium was found to decrease both the growth and nucleation rates of calcium oxalate crystals in the simulated renal environment.

Calcium Oxalate↗
PubMed1981

The nucleation and growth kinetics of calcium oxalate in the presence of some synthetic urine constituents.

We determined quantitative nucleation and growth kinetics of calcium oxalate in the presence of various combinations of urine constituents, using a continuous mixed suspension mixed product removal crystallizer and a Coulter counter. Nucleation rates of calcium oxalate from the pure component system were approximately an order of magnitude higher than those from an artificial urine. The presence of citrate inhibited nucleation rates under high conditions. The ions Na+, K+, NH4+, Cl-, and SO42- did not affect the overall kinetics in the synthetic urine. Di- and tri-hydrate products were formed, except when crystallizing from pure components, when only the thermodynamically stable monohydrate was observed.

Animals↗