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Biomedical subjects

S E Harrison

Publications and source records attributed to S E Harrison.

18 recordsLinked to original sources
PubMed2004

Real-time monitoring of intracellular Staphylococcus aureus replication.

A high-throughput system to rapidly assess the intracellular replication of Staphylococcus aureus has been developed utilizing S. aureus transformed with a dual gfp-luxABCDE reporter operon under the control of a growth-dependent promoter. Replication of tagged bacteria internalized into bovine mammary epithelial cells (MAC-T) could be measured by monitoring fluorescence and bioluminescence from the reporter operon following removal of extracellular bacteria from the plates. Bacterial replication inside cells was confirmed by a novel ex vivo time-lapse confocal microscopic method. This assay of bacterial replication was used to evaluate the efficacy of antibiotics which are commonly used to treat staphylococcal infections. Not all antibiotics tested were able to prevent intracellular replication of S. aureus and some were ineffective at preventing replication of intracellular bacteria at concentrations above the MIC determined for bacteria in broth culture. Comparison of the fluorescence and bioluminescence signals from the bacteria enabled effects on protein synthesis and metabolism to be discriminated and gave information on the entry of compounds into the eukaryotic cell, even if bacterial replication was not prevented. Elevated resistance of S. aureus to antibiotics inside host cells increases the likelihood of selecting S. aureus strains which are resistant to commonly used antimicrobial agents within the intracellular niche. The approach presented directly assesses intracellular efficacy of antibiotics and provides an evidence-based approach to antibiotic selection for prescribing physicians and medical microbiologists.

Animals↗
PubMed2001

The modified Lothrop procedure: indications, results, and complications.

The modified Lothrop procedure or frontal sinus drill-out is a completely intranasal technique that creates a common frontonasal communication to allow drainage and ventilation of the chronically infected frontal sinus. It is an effective alternative to the classic frontal sinus obliteration. The modified Lothrop is usually performed on an outpatient basis, leaves no external scars, provides excellent visualization of the frontal sinus in the postoperative setting, and yields a high cure rate in chronically infected patients.

Chronic Disease↗
PubMed1987

The influence of calcium on glucose metabolism in the rabbit lens.

Results were obtained which demonstrate that calcium accumulation in the rabbit lens may suppress glycolysis, not only by its inhibitory effect on cation transport but by its direct effect on glycolytic enzymes. In lenses cultured in calcium-enriched medium, lactate production declined in proportion to the increase in free and bound levels of calcium. In lens homogenates to which varying amounts of calcium were added, lactate production also decreased. To insure that excess calcium was not simply chelating ATP, homogenates were exposed to calcium and then dialyzed against a calcium-free buffer prior to addition of ATP. Under these conditions, lactate production diminished maximally by approximately 50% as bound calcium increased five-fold.

Animals↗
PubMed1985

Effects of intracellular calcium on lens membrane permeability.

The present investigation was designed to assess whether lens membrane permeability is affected by changes in levels of intracellular calcium. Lanthanum, an inhibitor of Ca-ATPase, affected an increase in the concentration of intracellular calcium (Cai) measured in cortical fiber cells. Preculture of lenses in lanthanum (1.0mM) caused an accumulation of 36Cl during subsequent culture at a rate three-fold higher than control lenses. Changes in calcium levels, however, were not responsible for the observed flux changes because a 40mV depolarization was observed to occur prior to a significant increase in calcium levels. The non-specific effects of lanthanum and other potential inhibitors of calcium transport were avoided by preculturing lenses in an ion-HEPES medium containing 20mM calcium chloride. In lenses with a six-fold increase in calcium levels there resulted only a 10% increase in 36Cl uptake over a 3 hr period. 86Rb efflux was also measured and the rate constant was unchanged compared to control lenses. Calcium accumulation did lead to a small (8mV) depolarization which may account for the small increase in chloride accumulation. By light microscopy, morphology of cortical lens fibers and the epithelium appeared unchanged in the calcium-loaded lens. The results provide little evidence that an increase in Cai leads to acute changes in lens membrane permeability.

Body Fluids↗
PubMed1983

Fates of metal radiotracers added to a whole lake: accumulation in slimy sculpin (Cottus cognatus) and white sucker (Catostomus commersoni).

Six gamma-emitting isotopes, iron-59, cobalt-60, zinc-65, selenium-75, cesium-134 and mercury-203, were added in mid-summer to Lake 224 of the Experimental Lakes Area in northwestern Ontario, Canada. Isotope activities in whole bodies of slimy sculpins and in blood, gills, gut contents, kidney, liver and spleen of white suckers were determined for periods up to 247 days after isotope addition. Results demonstrate delay between contamination of a lake and transfer of contaminant to these fish species. General relationships between movement and distribution of isotopes in water and their accumulation in these fish indicate that direct accumulation from water is not a major route of uptake.

Animals↗
PubMed1982

Enzyme polymorphism in Trichinella.

The isoenzyme profiles of five isolates of the supposed 'species' of Trichinella, T. nativa, T. spiralis and T. nelsoni were compared. Four enzymes (AK, PGM, MPI and GPI) gave good resolution and clearly differentiated T. Spiralis from the other two species. T. nativa and T. nelsoni had similar isoenzyme patterns; the two separate isolates of T. nativa and T. spiralis used gave similar results, thus indicating the validity and the reproducibility of the technique. The value of enzyme electrophoresis for specific and subspecific classification of Trichinella is discussed and compared with the more traditional methods of taxonomy which have failed to resolve the controversy surrounding speciation.

Electrophoresis, Starch Gel↗
PubMed1982

A new and effective protective agent for intraocular lens insertion.

Chondroitin sulfate (CDS) has been found to serve as an excellent protective coating for intraocular lens (IOL) implantation to avoid any damage to the corneal endothelium; the protection is total. Using a new vital dye, acid violet 49, as a stain, a series of possible coatings including albumin and hyaluronic acid was evaluated in vitro and in vivo. Some 600 animal corneas were trephined, and the sample buttons submitted to the dragging of variously coated lenses across the endothelium. The animal species were rabbit, pig, cow, dog, cat, and monkey. IOLs were traumatically inserted in rabbits and monkeys. Chondroitin sulfate surpassed by far the protective qualities of other compounds: albumin was second best; hyaluronic acid third, the latter two yielding substantial damage in our tests. Comparisons with the commercially available Healon still revealed chondroitin sulfate to be the most efficacious protective agent. The material was eliminated from the anterior chamber in periods less than 40 hours. Monitoring of postoperative intraocular pressures revealed only normal pressures in our animals.

Albumins↗
PubMed1981

Health service computing: putting the patient on line.

The potential of computers for speeding up communications and routine decision-making in hospitals is still not being fully exploited. S. E. Harrison, formerly regional management services officer, SW Thames RHA, considers what hospitals need from a patient administration system and how it might be achieved.

Computers↗
PubMed1980

Evaluation and protection of corneal endothelium.

A series of experiments was performed in vitro, on animal and human corneas, and in vivo, on monkeys and rabbits, to test the efficacy of various substances which may be used as coatings for intraocular lenses to protect the corneal endothelium from damage. The vital dye, acid violet 49, was applied to evaluate endothelial cell function and damage. Our results indicate that chondroitin sulphate is far superior to other substances tested in preventing endothelial damage due to intraocular lens contact. Acid violet 49 is very sensitive in detecting endothelial cell damage, and the intensity of cellular staining with acid violet 49 correlates well with the degree of endothelial cell damage.

Animals↗
PubMed1979

Basic concepts and an overview of cryosurgery in ophthalmic plastic surgery.

In cryosurgery, a rapid double freeze using liquid nitrogen spray coupled with a slow thaw generates optimum cell destruction. Important factors in using the cryosurgical technique include temperature monitoring of the lesion, the type of instrumentation, the type of cryogen, and the nonhomogeneity of human tissue. Physiological processes occurring subsequent to cryogen application cause tissue necrosis. Cryosurgery is indicated for treatment of some basal cell carcinomas and occasional squamous cell carcinomas; most other lesions should be treated by surgical excision at the present time. The authors are involved in research to determine means of observing tissue destruction, temperature monitoring and control methods, and evaluation of post-thawing processes.

Animals↗