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Biomedical subjects

B Gee

Publications and source records attributed to B Gee.

At least 19 recordsLinked to original sources
PubMed2003

Comparison of the performance of selenite cystine and mannitol selenite enrichment broths in the isolation of Salmonella spp. from faeces.

Over a four-month period, 4,658 routine faecal samples were examined in four laboratories and the isolation rates of Salmonella spp. from mannitol selenite (MS) and selenite cystine (SC) broths plated to xylose lysine desoxycholate agar (XLD) compared. The isolation rate by MS was 1.55% and by SC was 1.48%, a small difference which is not statistically significant. Significantly fewer colonies were selected for supplementary testing from SC than MS (p = 0.029), thus reducing confirmatory work. In laboratories where SC is already used for food and environmental work, an opportunity exists to limit stocked salmonella enrichment broths to SC alone.

Culture Media↗
PubMed2002

Periorbital dermatitis as a side effect of topical dorzolamide.

AIM: To report periorbital dermatitis as a late side effect of topical dorzolamide hydrochloride (Trusopt), a drug used to reduce intraocular pressure. METHODS: A retrospective study of 14 patients who developed periorbital dermatitis while using topical dorzolamide hydrochloride was undertaken. Six patients underwent patch testing for sensitivity to Trusopt, dorzolamide hydrochloride, and the preservative benzalkonium chloride. RESULTS: The periorbital dermatitis occurred after a mean period of 20.4 weeks of commencing dorzolamide hydrochloride therapy. 13 patients had used preserved topical beta blocker treatment for a mean period of 34.2 months without complication before the introduction of dorzolamide. In eight (57.1%) the dermatitis resolved completely after discontinuing dorzolamide but in six (42.9%) resolution of the dermatitis did not occur until the concomitant preserved beta blocker was stopped and substituted with preservative free drops. Patch testing for sensitivity to Trusopt, dorzolamide hydrochloride, and benzalkonium chloride was negative. CONCLUSION: These findings suggest that dorzolamide can cause severe periorbital dermatitis. Although the dermatitis may resolve when dorzolamide is discontinued, this does not always occur and in some patients all topical medication containing benzalkonium chloride needs to be stopped.

Administration, Topical↗
PubMed2002

An evaluation of the performance of XLD, DCA, MLCB, and ABC agars as direct plating media for the isolation of Salmonella enterica from faeces.

AIMS: To compare the performance of four media, singly and in combination, as direct plating media for the isolation of Salmonella enterica from human faeces. METHODS: Two thousand four hundred and nine routine, faecal samples received by four laboratories were inoculated on to xylose lysine desoxycholate (XLD), desoxycholate citrate (DCA), mannitol lysine crystal violet brilliant green (MLCB), and alpha-beta chromogenic (ABC) agars using standardised protocols, reagents, and data collection. Isolates of presumptive salmonellae were identified using standard laboratory techniques and the results were analysed statistically. RESULTS: Direct plating recovered 46 of the 60 possible isolates of Salmonella spp recovered via enrichment broth. No isolates were recovered from direct plating that were not recovered via selenite enrichment. MLCB gave the highest isolation rate individually (84.8%) and amounts of competing flora (CF) did not affect the recognition of colonies. ABC proved highly specific, but insensitive, and isolation rates were adversely affected by any amount of CF. Isolation rates from XLD and DCA were only affected when the CF load was heavy. DCA was least specific, with only 9.01% of picks positive and greatest number of confirmatory tests. XLD and MLCB, in combination, gave the highest isolation rate. CONCLUSIONS: Where the earlier results of direct plating may be advantageous, XLD and MLCB provide the optimal combination. For non-typhi salmonellae, MLCB is the best, single direct plating medium. For routine diagnostic work, XLD is most effective.

Bacteriological Techniques↗
PubMed2002

A comparison of the performance of cystine lactose electrolyte deficient (CLED) agar with Oxoid chromogenic urinary tract infection (CUTI) medium for the isolation and presumptive identification of organisms from urine.

AIMS: As part of the UK antimicrobial resistance strategy and action plan, the Public Health Laboratory Service (PHLS) is required to collect antibiotic susceptibility data so that resistance trends and patterns can be monitored. Most laboratories report urine Gram negative isolates, as "coliforms" according to morphological appearance, but without an acceptable identification system the antimicrobial surveillance data will be meaningless. Commercially available identification systems tend to be expensive and time consuming. Chromogenic agars, which claim to improve the detection of mixed cultures and identification of organisms from urine, have now become available and may provide a cost effective alternative. The primary aim of this study was to compare the performance of cystine lactose electrolyte deficient (CLED) agar with a chromogenic agar (Oxoid urinary tract infection medium; CUTI) in terms of isolation rates and ability to detect mixed cultures. Secondary aims were to evaluate the correlation of "presumptive" identification of isolates from chromogenic media with that of two commercial identification systems and to appraise the sensitivity of the semiquantitative loop and filter paper strip culture techniques. METHOD: One thousand, four hundred and sixty six urine samples were examined in four laboratories using the semiquantitative culture methods of 1 microl loop and filter paper strip. The degree of accuracy of organism identification was measured by comparing the presumptive identification using colony colour supplemented with simple bench tests, with identification obtained from two more complex commercial systems. RESULTS: There was no significant difference between the performance of the loop and filter paper strip methods on the CLED agar, but the CUTI agar performed significantly better than the CLED agar for the detection of significant isolates and mixed cultures. This difference was greater using the loop method. Identification of the organisms using the commercial systems gave > 99% agreement and was therefore considered suitable as a standard against which to compare the presumptive CUTI identification. Using the manufacturer's colony colour criteria in combination with a bench indole test, the CUTI medium was 99% specific for Escherichia coli, although this was reduced to 97% if the indole test was omitted. Citrobacter spp were the most commonly misidentified organisms, giving false presumptive identification as E coli. By testing oxidase activity to differentiate Pseudomonas spp and the absence of indole production to support the identification of Proteus mirabilis, the CUTI medium provided a suitable identification for 86.8% of Gram negative isolates. The remaining 13.2% would require further identification. CONCLUSION: CUTI medium improves the detection of mixed cultures, thereby improving the reliability of reporting of significant isolates when compared with CLED agar. When supplemented with simple bench tests it provides an identification system capable of speciating 86.8% of Gram negative isolates and providing a valuable cost effective mechanism for antimicrobial resistance surveillance.

Agar↗
PubMed2002

Effect of incubation temperature on the isolation of thermophilic species of Campylobacter from faeces.

Although no large-scale clinical study has been performed, it has been reported that incubation at 37 degrees C gives better isolation rates for all common species of Campylobacter than incubation at 42 degrees C, while also improving the recovery of the more unusual species. In this study, 2,570 faecal samples were examined in four laboratories, using a standardised protocol. Isolation rates of Campylobacter spp. were compared after incubation on modified campylobacter blood-free selective agar at 37 degrees C and 42 degrees C. Campylobacter spp. isolates were made from 185 samples (7.2%); 25 were recovered only at 42 degrees C and three only at 37 degrees C (p < 0.001). There were significantly more colonies at 42 degrees C (p = 0.001). Competing flora were heavier at 37 degrees C, but this did not account for the difference in isolation rates or quantity of growth. It is recommended that cultures for Campylobacter spp. be routinely incubated at 42 degrees C. More specific techniques are required to seek for fastidious campylobacters.

Agar↗
PubMed2002

Comparison of the performance of lactose and mannitol selenite enriched broths, subcultured to DCA and XLD agars, in the isolation of Salmonella spp. from faeces.

Selenite-based enrichment broths using either lactose or mannitol as a carbohydrate source are generally used as selective enrichment media for the isolation of Salmonella spp. from human faeces in the UK, but few studies have compared the relative efficacy of the available formulations. A variety of solid media is used for the routine subculture from these selective broths, but similarly we have been unable to find published evidence as to which medium performs best. Four thousand and nineteen faecal samples were examined in four laboratories and the isolation rates of Salmonella spp. from lactose (LS) or mannitol selenite (MS) broths, plated onto either xylose lysine desoxycholate agar (XLD) or desoxycholate citrate agar (DCA) were compared. MS performed significantly better than LS (p = 0.02), recovering 95 salmonellae compared with 87. No significant difference in isolation rates was found between XLD and DCA, although colonial appearances of suspected salmonellae on XLD were much more specific, resulting in significantly fewer colonies having to be selected for supplementary testing (p < 0.001) and so reducing confirmatory work. An opportunity exists to simplify holdings of media by choosing to use the MS/XLD combination.

Bacteriological Techniques↗
PubMed2001

A comparison of the performance of bacitracin-incorporated chocolate blood agar with chocolate blood agar plus a bacitracin disk in the isolation of Haemophilus influenzae from sputum.

The lack of selectivity of chocolated blood agar (CBA), routinely used for the isolation of Haemophilus influenzae, may lead to masking of the growth of H. influenzae due to overgrowth of competing flora. Bacitracin can be used as a selective agent, either incorporated into the medium or applied to the medium in a filter paper. However, neither method has been evaluated or compared in a large study. Sputum samples (1990) were examined in four laboratories and the isolation rates of H. influenzae on chocolated blood agar with bacitracin added to the medium (BCA) and chocolated blood agar (CBA) with a bacitracin disk were compared. A plain blood agar plate was also inoculated to facilitate the isolation of Streptococcus pneumoniae so that its effects on the isolation of H. influenzae could be assessed. No significant difference was found between the isolation rates of H. influenzae on BCA and CBA with a bacitracin disk, although competing flora was greatly reduced and quantity of growth of H. influenzae increased on BCA. The presence of S. pneumoniae did not affect the isolation of H. influenzae in this study.

Anti-Bacterial Agents↗
PubMed2001

A comparison of the isolation rates of Salmonella and thermophilic Campylobacter species after direct inoculation of media with a dilute faecal suspension and undiluted faecal material.

Regardless of media used, dilution of faecal samples before direct plating may improve isolation rates and reduce subcultures by freeing organisms from the faecal mass and diminishing competing flora. Despite the routine use of dilution in many laboratories, it has never been established properly whether direct or dilute inocula should be used in primary plating of faeces. A total of 3764 faecal samples was examined in four laboratories with a standardised methodology. The isolation rates, competing flora and confirmatory work performed for Salmonella spp. and Campylobacter spp. from primary plating media with a dilute faecal inoculum were compared with those after direct inoculation of faecal material. Inoculum effects on the isolation of Shigella spp. could not be assessed as only one isolate occurred during the study period. The overall isolation rates of both major enteric pathogens were unaffected by the inoculum. However, significantly fewer wasted subcultures were recorded with a dilute inoculum for Campylobacter spp., and competing florawas reduced in all cases without diluting out small numbers of the pathogen.

Campylobacter↗
PubMed1999

Safety of hydroxyurea in children with sickle cell anemia: results of the HUG-KIDS study, a phase I/II trial. Pediatric Hydroxyurea Group.

Previous studies have determined the short-term toxicity profile, laboratory changes, and clinical efficacy associated with hydroxyurea (HU) therapy in adults with sickle cell anemia. The safety and efficacy of this agent in pediatric patients with sickle cell anemia has not been determined. Children with sickle cell anemia, age 5 to 15 years, were eligible for this multicenter Phase I/II trial. HU was started at 15 mg/kg/d and escalated to 30 mg/kg/d unless the patient experienced laboratory toxicity. Patients were monitored by 2-week visits to assess compliance, toxicity, clinical adverse events, growth parameters, and laboratory efficacy associated with HU treatment. Eighty-four children were enrolled between December 1994 and March 1996. Sixty-eight children reached maximum tolerated dose (MTD) and 52 were treated at MTD for 1 year. Significant hematologic changes included increases in hemoglobin concentration, mean corpuscular volume, mean corpuscular hemoglobin, and fetal hemoglobin parameters, and decreases in white blood cell, neutrophil, platelet, and reticulocyte counts. Laboratory toxicities typically were mild, transient, and were reversible upon temporary discontinuation of HU. No life-threatening clinical adverse events occurred and no child experienced growth failure. This Phase I/II trial shows that HU therapy is safe for children with sickle cell anemia when treatment was directed by a pediatric hematologist. HU in children induces similar laboratory changes as in adults. Phase III trials to determine if HU can prevent chronic organ damage in children with sickle cell anemia are warranted.

Adolescent↗
PubMed1999

A comparison of blood agar supplemented with NAD with plain blood agar and chocolated blood agar in the isolation of Streptococcus pneumoniae and Haemophilus influenzae from sputum. Bacterial Methods Evaluation Group.

Streptococcus pneumoniae grows well and generally exhibits typical morphology on Columbia blood agar, whereas Haemophilus influenzae requires a more complex medium to meet its growth requirements - usually chocolated blood agar - on which S. pneumoniae is less easily recognisable. Therefore, a single medium that produces typical morphology of S. pneumoniae and facilitates the growth of H. influenzae would have considerable potential advantages. It has been claimed that blood agar supplemented with nicotinamide adenine dinucleotide (NAD) is such a medium. However, despite its routine use in several large diagnostic laboratories its performance has never been properly evaluated. In the present study, 1724 sputum samples were examined in four laboratories. The isolation rates of H. influenzae and S. pneumoniae on NAD-supplemented blood agar (SBA) were compared with those on a two-plate combination of plain blood (BA) and chocolated blood agar (CBA). The two-plate combination performed significantly better for both organisms; isolation rates for H. influenzae were increased from 8.16% on SBA to 11.07% on BA plus CBA and for S. pneumoniae from 4.18% to 4.68%. Isolation rates were also compared after incubation for 24 and 48 h. With the two-plate combination, isolation rates for H. influenzae and S. pneumoniae were increased by 0.98% and 0.16%, respectively, and for SBA by 0.57% and 0.32% after 48 h. However, despite this increase, SBA still performed less well than the two-plate combination.

Agar↗
PubMed1996

Therapy with oral clotrimazole induces inhibition of the Gardos channel and reduction of erythrocyte dehydration in patients with sickle cell disease.

Pathologic water loss from sickle erythrocytes concentrates the abnormal hemoglobin and promotes sickling. The Ca2+-activated K+ channel (Gardos channel) contributes to this deleterious dehydration in vitro, and blockade of K+ and water loss via this channel could be a potential therapy in vivo. We treated five subjects who have sickle cell anemia with oral clotrimazole, a specific Gardos channel inhibitor. Patients were started on a dose of 10 mg clotrimazole/kg/d for one week. Protocol design allowed the daily dose to be escalated by 10 mg/kg each week until significant changes in erythrocyte density and K+ transport were achieved. Blood was sampled three times a week for hematological and chemical assays, erythrocyte density, cation content, and K+ transport. At dosages of 20 mg clotrimazole/kg/d, all subjects showed Gardos channel inhibition, reduced erythrocyte dehydration, increased cell K+ content, and somewhat increased hemoglobin levels. Adverse effects were limited to mild/moderate dysuria in all subjects, and a reversible increase in plasma alanine transaminase and aspartic transaminase levels in two subjects treated with 30 mg clotrimazole/kg/d. This is the first in vivo evidence that the Gardos channel causes dehydration of sickle erythrocytes, and that its pharmacologic inhibition provides a realistic antisickling strategy.

Administration, Oral↗
PubMed1995

23Na nuclear magnetic resonance spin echo decay spectroscopy of sodium silicate glasses and crystalline model compounds.

The possibility of using Hahn spin echo decay spectroscopy for measuring 23Na-23Na dipole-dipole couplings in crystalline solids and glasses is investigated. Although the presence of nuclear electric quadrupolar splittings complicates the situation compared to the case of dipole-dipole couplings among spin-1/2 nuclei, experimentally measured second moments lie within approximately 10-20% of the calculated values, if the following conditions are fulfilled: (1) selective excitation of the central 1/2-->-1/2 transition, and (2) restriction of the analysis to short evolution times (2t1 < or = 200 microseconds). At longer evolution times, partial suppression of the spin-exchange term in the dipolar Hamiltonian due to magnetic inequivalencies between the interacting nuclei produces substantial differences between experimental and calculated spin echo decays, the extent of which depends on the compound considered. These results signify the potential utility of 23Na spin echo nuclear magnetic resonance for testing the distribution of Na-Na distances in structurally disordered solids and glasses. The method is shown to be applicable to sodium silicate glasses, where it reproduces anticipated compositional trends in 23Na-23Na couplings. Details and inherent limitations of this methodology are discussed.

Crystallization↗
PubMed1995

Penetrating keratoplasty after radial keratotomy. A report of six patients.

BACKGROUND: For more than 15 years, radial keratotomy has increased in popularity as an option for treating myopia in the United States. During this period of time, the procedure has been modified to improve results and decrease complications. Despite these changes, complications from radial keratotomy continue to occur. The authors report six cases of penetrating keratoplasty performed to correct significant loss of vision resulting from complications of radial keratotomy. METHODS: The surgical records of one author (WR) were reviewed retrospectively for penetrating keratoplasties performed for complications of radial keratotomy. RESULTS: Six cases of penetrating keratoplasty performed for complications of radial keratotomy were found. Severe loss of vision was the indication for surgery in each case, and was associated with aggressive and repeated incisional refractive attempts to correct astigmatism, hyperopic overcorrection, residual myopia, or refractive errors associated with keratoconus. Glare associated with subepithelial scarring and irregular astigmatism were the primary findings associated with loss of vision. CONCLUSIONS: Despite advances in technique and instrumentation, radial keratotomy is limited in the amount of myopia it can correct. The risk for loss of vision increases with increasing number of incisions, intersecting incisions, very small optical zones, and keratoconus.

Adult↗
PubMed1995

Colorimetric method for determining MICs of antimicrobial agents for Mycobacterium tuberculosis.

A colorimetric method for quantitative measurement of the susceptibility of Mycobacterium tuberculosis to antimicrobial agents is described. The method utilizes an oxidation-reduction dye, Alamar blue, as an indicator of growth. By this method, MICs of isoniazid, rifampin, streptomycin, and ethambutol were determined for 50 strains of M. tuberculosis. Colorimetric MIC results were available on the 7th, 10th, or 14th day of incubation for 29 (58%), 14 (28%), and 7 (14%) of the 50 strains, respectively. When MIC susceptibility results were compared with results obtained by the agar proportion method, increased levels of resistance detected by agar proportion were associated with higher MICs obtained by the colorimetric method. Tentative interpretive criteria for colorimetric MIC results which showed good agreement with results obtained by the agar proportion method were established. Interpretive agreement between the two methods was 98% for isoniazid, rifampin, and ethambutol and 94% for streptomycin. Overall, there was agreement between the two methods for 194 of 200 test results (97%). The colorimetric method is a rapid, quantitative, nonradiometric method for determining the antimicrobial susceptibility of M. tuberculosis.

Antibiotics, Antitubercular↗
PubMed1991

Use of anti-horseradish peroxidase antibody-gold complex in the ABC technique.

We report a modification of the avidin-biotin-peroxidase complex (ABC) technique for the light and electron microscopic detection of antigens in tissue sections. An immunological approach was used instead of the DAB reaction to reveal ABC bound to antigen-antibody complexes. Affinity-purified polyclonal antibodies against horseradish peroxidase were complexed to particles of colloidal gold and applied for reaction with the horseradish peroxidase molecules of the ABC. For light microscopic immunolabeling, the signal produced by the anti-horseradish peroxidase antibody-gold complex required silver intensification. The ABC immunogold reaction as compared with the standard ABC technique, in particular with silver intensification of the DAB reaction product, provided superior resolution in paraffin sections. Furthermore, section pre-treatment to block endogenous peroxidase activity could be omitted and no potentially hazardous substrate was used. The ABC immunogold reaction was successfully applied for electron microscopic immunolabeling on Lowicryl K4M thin sections. We propose that the ABC immunogold reaction is a useful alternative to the standard ABC technique and can be equally well applied to light and electron microscopy.

Adenocarcinoma↗