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Biomedical subjects

G Roberts

Publications and source records attributed to G Roberts.

At least 37 records · Page 2Linked to original sources
PubMed2001

Comparison of the BACTEC MYCO/F Lytic bottle to the isolator tube, BACTEC Plus Aerobic F/bottle, and BACTEC Anaerobic Lytic/10 bottle and comparison of the BACTEC Plus Aerobic F/bottle to the Isolator tube for recovery of bacteria, mycobacteria, and fungi from blood.

The BACTEC MYCO/F Lytic blood culture bottle (Becton Dickinson Diagnostic Instrument Systems, Sparks, Md.) is designed to optimize the recovery of fungi and mycobacteria; however, this bottle also supports the growth of most aerobic bacteria. We compared the MYCO/F Lytic bottle with two other BACTEC bottles and the Isolator system for the recovery of bacteria as well as fungi and mycobacteria from blood. A total of 6,108 blood culture sets were inoculated with blood obtained from adult patients. Twenty-five to 28 ml of blood collected by a phlebotomy team for each blood culture set was randomly distributed into each of four blood culture receptacles: the Isolator tube (Wampole Laboratories, Cranbury, N.J.) and three BACTEC bottles: the MYCO/F Lytic bottle, the BACTEC Plus Aerobic/F bottle, and the BACTEC Anaerobic Lytic/10 bottle. The sediment from the Isolator tube was inoculated onto chocolate agar (CA), brain heart infusion agar (BHI), and Sabouraud dextrose agar (SDA) and into a BACTEC 13A bottle. Incubation durations were as follows: MYCO/F Lytic bottle, 42 days; Plus Aerobic/F bottle, 5 days; Anaerobic Lytic/10 bottle, 5 days; sediment from Isolator tube on CA, 3 days; sediment from Isolator tube on BHI, 30 days; sediment from Isolator tube on SDA, 30 days; and sediment from Isolator tube in a BACTEC 13A bottle, 42 days. Two isolates of Histoplasma capsulatum were recovered from the Isolator tube only. Three isolates of Mycobacterium tuberculosis complex were recovered: two isolates from the MYCO/F Lytic bottle only and one isolate from the Isolator tube (whose sediment was inoculated into the BACTEC 13A bottle) only. Two isolates of Cryptococcus neoformans were recovered: one from the MYCO/F Lytic bottle only and the other from the MYCO/F Lytic bottle and the Isolator tube (whose sediment was inoculated into the BACTEC 13A bottle). For potential pathogens overall, there was a statistical difference in recovery that favored the Isolator system over the MYCO/F Lytic bottle (P = 0.0015), including statistically significant differences for Staphylococcus aureus (P = 0.0001) and Streptococcus pneumoniae (P = 0.0313). However, there was no statistically significant difference between the two blood culture systems when detection of bloodstream infection was considered. The time to detection for all potential pathogens combined was less for the MYCO/F Lytic bottle than for the Isolator system (P = 0.0004). Overall, the potential pathogen recovery was greater for the BACTEC Plus Aerobic/F bottle than for either the Isolator system (P = 0.0003) or the MYCO/F Lytic bottle (P = 0.0001). However, the BACTEC Plus Aerobic/F bottle did not recover M. tuberculosis, H. capsulatum, or C. neoformans isolates. The combination of the Isolator system and MYCO/F Lytic bottle may be useful as a selective blood culture method to optimize the recovery of fungi and mycobacteria from blood. Compared with the manual Isolator system, the MYCO/F Lytic system has the advantage of less preanalytic processing and continuous automated monitoring of bottles for growth by the BACTEC 9240 instrument.

Adult↗
PubMed2001

Mannosidase production by viridans group streptococci.

The production of mannosidase activity by all currently recognized species of human viridans group streptococci was determined using an assay in which bacterial growth was dependent on the degradation of the high-mannose-type glycans of RNase B and subsequent utilization of released mannose. RNase B is an excellent substrate for the demonstration of mannosidase activity since it is a glycoprotein with a single glycosylation site which is occupied by high-mannose-type glycoforms containing five to nine mannose residues. Mannosidase activity was produced only by some members of the mitis group (Streptococcus mitis, Streptococcus oralis, Streptococcus gordonii, Streptococcus cristatus, Streptococcus infantis, Streptococcus parasanguinis, and Streptococcus pneumoniae) and Streptococcus intermedius of the anginosus group. None of the other species within the salivarius and mutans groups or Streptococcus peroris and Streptococcus sanguinis produced mannosidase activity. Using matrix-assisted laser desorption ionization time-of-flight mass spectrometry, it was demonstrated that the Man(5) glycan alone was degraded while Man(6) to Man(9), which contain terminal alpha(1-->2) mannose residues in addition to the alpha(1-->3), alpha(1-->6), and beta(1-->4) residues present in Man(5), remained intact. Investigations on mannosidase production using synthetic (4-methylumbelliferone- or p-nitrophenol-linked) alpha- or beta-mannosides as substrates indicated that there was no correlation between degradation of these substrates and degradation of the Man(5) glycan of RNase B. No species degraded these alpha-linked mannosides, while degradation of the beta-linked synthetic substrates was restricted to strains within the Streptococcus anginosus, S. gordonii, and S. intermedius species. The data generated using a native glycoprotein as the substrate demonstrate that mannosidase production within the viridans group streptococci is more widely distributed than had previously been considered.

Culture Media↗
PubMed2001

Supporting children with serious health care needs. Analyzing the costs and benefits.

Effective and efficient service delivery to children who rely on medical technology or ongoing medical care will become increasingly critical as technology and medical know-how grow more sophisticated. Presently, technology's development and application threaten to outpace systems of service delivery. This article explores the present state of affairs by considering the challenges involved in planning and evaluating programs for children with special health care needs and their families. A cost-benefit model is suggested as a meaningful framework for considering challenges related to providing service in this arena and evaluating its effectiveness.

Child↗
PubMed2001

The reproducibility of assessing radiological reporting: studies from the development of the General Medical Council's Performance Procedures.

OBJECTIVES: To investigate the reproducibility of peer ratings of consultant radiologists' reports, as part of the new General Medical Council (GMC) Performance Procedures. DESIGN: An evaluation protocol was piloted, used in a blocked, balanced, randomized generalizability analysis with three blocks of three judges (raters), each rating 30 reports from 10 radiologists, and re-rated to estimate intrarater reliability with conventional statistics (kappa). SETTING: Rating was performed at the Royal College of Radiologists. Volunteers were sampled from 23 departments of radiology in university teaching and district general hospitals. PARTICIPANTS: A nationally drawn non-random sample of 30 consultant radiologists contributing a total of 900 reports. Three trained and six non-trained judges were used in the rating analysis. RESULTS: A protocol was generated that was usable by judges. Generalizable results would be obtained with not less than three judges all rating the same 60 reports from a radiologist. CONCLUSIONS: Any assessment of performance of technical abilities in this field will need to use multiple assessors, basing judgements on an adequate sample of reports.

Clinical Competence↗
PubMed2000

A cost-outcome analysis of adjuvant postmastectomy locoregional radiotherapy in premenopausal node-positive breast cancer patients.

PURPOSE: To calculate cost-effectiveness and cost-utility ratios for adjuvant postmastectomy locoregional radiotherapy in premenopausal node-positive breast cancer patients and to place these ratios in the context of generally accepted medical expenditures. MATERIALS AND METHODS: A spreadsheet-based activity costing model using 1997 Canadian (cdn) capital, operating, and administrative costs has been used to identify, from the institutional perspective, the incremental cost of adding radiotherapy to surgery and chemotherapy for this group of patients. Outcome data were derived from two recently published clinical trials and were converted to discounted incremental life years and quality-adjusted life years gained. Recommended health economics principles were employed in the quantification of both costs and outcomes, and a sensitivity analysis was performed. Three referenced publications provide a context within which to evaluate the calculated cost-effectiveness and cost-utility ratios. RESULTS: The incremental cost of adjuvant radiotherapy for this group of patients is calculated to be approximately $7,000cdn in 1997 Canadian dollars and in the Canadian socialized health-care environment. Based on published work the discounted incremental outcome benefit is calculated to be 0.5 life years or 0.45 quality-adjusted life years at ten years. Thus, cost effectiveness and cost-utility ratios are estimated to be $14,000cdn and $15,600cdn, respectively. CONCLUSION: Within the context of generally accepted medical expenditures, adjuvant postmastectomy locoregional radiotherapy for premenopausal node-positive breast cancer patients would be regarded as a cost-effective treatment strategy.

Breast Neoplasms↗
PubMed2000

Detecting mannosidase activities using ribonuclease B and matrix-assisted laser desorption/ionization-time of flight mass spectrometry.

Ribonuclease (RNase) B incubated with purified enzymes, whole bacterial cultures, or their separated components-cells and supernates-have been directly analyzed by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-ToF) to detect exomannosidases and to evaluate their specificities and location. Enzymatic cleavage was monitored by observing changes in RNase B glycoform population. Thus a nonspecific alpha-(1 --> 2)-mannosidase activity converts the glycoprotein to its Man(5) form, identifiable by its mass of 14,899 [M + H](+); this species subsequently is converted, by the actions of alpha-(1 --> 3) and alpha-(1 --> 6)-mannosidases, to the Man(1) form via Man(4), Man(3), and Man(2). The Man(1) glycoform (which is readily isolated) has then similarly been used for identifying beta-(1 --> 4)-mannosidase and the derived Man(0) form has served in turn as a natural substrate for beta-(1 --> 4) N-acetylglucosaminidase producing a species possessing a single asparagine-linked GlcNAc residue (mass 13,886). Mannose liberated from the actions of mannosidases can, if desired, be quantified by, for example, chromatography. The actions and specificities of endoglycosidases such as a peptide-N-glycosidase F (PNGase F) and of endo-N-acetlyglucosaminidases (e.g., endo-F and endo-H), which respectively cleave between the GlcNAc&bond;Asn and GlcNAc&bond;GlcNAc bonds of N-linked glycoproteins, are also demonstrable by MALDI-ToF analysis of RNase B (and derived products). From these digests the completely deglycosylated polypeptide corresponding to RNase A in which Asn has been converted to Asp (mass 13,684) and a species corresponding to RNase A + GlcNAc (mass 13,886) are produced, together with their corresponding free oligosaccharides which are amenable to analysis by both MALDI-ToF and by HPLC.

Amidohydrolases↗
PubMed2000

Oral health status of children in a Paediatric Intensive Care Unit.

OBJECTIVE: The aim of the present study was to examine the dental status of critically ill children in a Paediatric Intensive Care Unit (PICU) and determine the efficacy of the mouth care received. DESIGN: Prospective nonrandomized study. SETTING: The study was carried out in the PICU at Great Ormond Street Hospital for Children. PATIENTS AND PARTICIPANTS: All children admitted to the PICU during the period of the study were eligible for inclusion. A total of 54 children completed the study. MEASUREMENTS AND RESULTS: Children were examined for dental caries, plaque accumulation, gingival inflammation and gingival bleeding on admission to the PICU. The examination was repeated on discharge from the Unit. The levels of dental caries found on examination were compared with results from the most recent national surveys carried out in the United Kingdom, and analysed using the one sample t-test. The levels of plaque accumulation, gingival inflammation and gingival bleeding on admission were compared to those on discharge and analysed using the paired sample t-test. Results revealed a very highly significant increase in plaque accumulation (p = 0.001), and a highly significant increase in gingival inflammation (p = 0.006) between admission to the PICU and discharge. CONCLUSIONS: Results indicate that the present mouth care regimen is not effective in preventing the build up of plaque or maintaining gingival health. These children may therefore be at unnecessary risk from local or systemic spread of oral microorganisms.

Child, Hospitalized↗
PubMed2000

Acute disseminated encephalomyelitis--a diagnosis to consider.

UNLABELLED: The case history of an 11-year-old boy with post-infectious acute disseminated encephalomyelitis (ADEM) is presented. ADEM is a diagnosis that is increasingly being made with the advent of modern radiological techniques. However, the syndrome cannot be thought of as a discrete clinical entity as it is triggered by a wide range of factors including infections and vaccinations. Furthermore, other pathological processes may give the same radiological appearances. The aetiology, pathophysiology and management of the syndrome are discussed. CONCLUSION: Acute disseminated encephalomyelitis is a radiological diagnosis that has many precipitants. Thought must be applied in developing a differential diagnosis to allow the possibility of targeting treatment at the underlying cause.

Child↗
PubMed2000

An economic framework for evaluating a multileaf collimator.

OBJECTIVES: As health care budgets continue to face close scrutiny, any new acquisition must be evaluated for both costs and outcomes. This study was undertaken to demonstrate the application of an economic framework for the evaluation of a multileaf collimator as an example of a new technology that can have both quantifiable and nonquantifiable benefits for patients, staff, and cancer care institutions. METHODS: Using financial data from the Northeastern Ontario Regional Cancer Centre (NEORCC) and a recognized staffing model, a commercial spreadsheet, developed to economically characterize the principal radiotherapy processes has been used to determine the net incremental annual cost of a multileaf collimator (MLC). RESULTS: The incremental annual cost of purchasing an MLC is estimated at approximately $85,000 (1997 CDN $). Without increasing patient throughput, this increases the average cost of a course of radiotherapy by approximately CDN $200. Savings can be accrued by decreasing mold room activity, increasing the hourly patient capacity on each treatment machine, and decreasing sick time due to strain injuries. CONCLUSIONS: Although the clinical outcome of techniques facilitated by MLCs, such as intensity-modulated radiation therapy, are unknown at this time, an economic context within which to objectively evaluate this technology is presented. The framework presented suggests a method of quantifying outcome-justified expenditures, such as improved patient outcome and greater treatment flexibility, which, when offset against the incremental annual equipment cost, may be used to help justify the acquisition of multileaf technology.

Capital Expenditures↗