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Biomedical subjects

G Roberts

Publications and source records attributed to G Roberts.

At least 73 records · Page 4Linked to original sources
PubMed2000

Tropisetron plus dexamethasone is more effective than tropisetron alone for the prevention of postoperative nausea and vomiting in children undergoing tonsillectomy.

The 5-HT3 antagonists are effective in reducing postoperative nausea and vomiting (PONV) associated with paediatric tonsillectomy. Although prophylactic tropisetron can reduce the incidence of PONV by half, the resulting level of over 40% is still unacceptably high. The aim of this study was to evaluate the effect of adding dexamethasone to tropisetron. In a blinded study, 59 children (mean age 6.1 years) were administered 0.1 mg.kg-1 up to 2 mg of tropisetron and 66 children (mean age 5.7 years) received the same dose of tropisetron plus 0.5 mg.kg-1 up to 8 mg of dexamethasone. Both drugs were given intravenously during induction of anaesthesia for tonsillectomy. During the inpatient stay of 24 h, the incidence of postoperative vomiting in the tropisetron alone group was 53% compared with 26% in the combination group (P=0.002, chi-squared). A significant reduction in nausea from 53% to 30% was also observed (P=0.02). Parents completed a daily diary for 5 days following discharge. Delayed vomiting occurred in 27% and 11% of the tropisetron and combination therapy groups, respectively (P=0.025) Sixteen percent and 9%, respectively, required medical attention (P=0.27). Tropisetron plus dexamethasone is more effective than tropisetron alone in reducing the incidence of PONV following paediatric tonsillectomy.

Adolescent↗
PubMed2000

Transnasal penetrating brain injury with a ball-pen.

We report a case of a 44-year-old man with 1 day's history of epistaxis. He was an in-patient in a psychiatric ward with a history of depression. He had CSF rhinorrhoea, was confused and had no focal neurological deficits. A full length pencil was removed from his left nostril in the emergency department. CT of the brain revealed a tract, but also suggested another foreign body in the inter-hemispheric space. He had a para-sagittal craniotomy and a 14 cm ball-point pen was found lying between the two cerebral hemispheres. This was removed and the patient made an uneventful recovery. This is the first report of an attempted suicide by transnasal insertion of a ballpoint pen intracranially.

Adult↗
PubMed2000

Evolutionary implications of phenotypic plasticity in the hindlimb of the lizard Anolis sagrei.

Species of Anolis lizards that use broad substrates have long legs, which provide enhanced maximal sprint speed, whereas species that use narrow surfaces have short legs, which permit careful movements. We raised hatchling A. sagrei in terraria provided with only broad or only narrow surfaces. At the end of the experiment, lizards in the broad treatment had relatively longer hindlimbs than lizards in the narrow treatment. These results indicate that not only is hindlimb length a plastic trait in these lizards, but that this plasticity leads to the production of phenotypes appropriate to particular environments. Comparison to hindlimb lengths of other Anolis species indicates that the range of plasticity is limited compared to the diversity shown throughout the anole radiation. Nonetheless, this plasticity potentially could have played an important role in the early stages of the Caribbean anole radiation.

Adaptation, Physiological↗
PubMed2000

Preventative maintenance and unscheduled downtime from an economic perspective.

A spreadsheet-based model for economically characterizing the operation of a radiation treatment program has been used to perform a quantitative financial analysis of scheduled and unscheduled downtime. The incremental cost of downtime is broken down into three categories: remuneration of in-house or third party service technologists, decreased patient capacity, and local operating procedures for dealing with downtime. Different service arrangements and operating procedures are simulated to demonstrate the financial cost of treatment machine unavailability due to either preventative maintenance or unexpected breakdown. Depending on the service arrangement and operating policies for accommodating downtime, the combined cost of scheduled and unscheduled downtime (at 5%) can exceed 10% of the total cost of the radiation treatment program. It has also been demonstrated that the greatest cost component of downtime is decreased patient capacity, which can exceed $400,000 (CAN) when unscheduled downtime reaches 5%. The interpretation of this cost depends on the funding environment. Although the emphasis of this study has been the financial consequences of downtime, there are other factors which must be considered when developing policies and procedures for accommodating downtime such as effects on treatment, patient convenience and quality of life for staff. Even though the numerical results are strictly valid only within the context of the simulations performed, they do provide a broad framework within which medical physicists can make recommendations regarding service support and downtime.

Canada↗
PubMed2000

Production of an endo-beta-N-acetylglucosaminidase activity mediates growth of Enterococcus faecalis on a high-mannose-type glycoprotein.

Enterococcus faecalis is associated with a high proportion of nosocomial infections; however, little is known of the ability of this organism to proliferate in vivo. The ability of RNase B, a model glycoprotein with a single N-glycosylation site occupied by a family of high-mannose-type glycans (Man(5)- to Man(9)-GlcNAc(2)), to support growth of E. faecalis was investigated. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of RNase B demonstrated a reduction in the molecular mass of this glycoprotein during bacterial growth. Further analysis by matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry revealed that this mass shift was due to the degradation of all high-mannose-type glycoforms to a single N-linked N-acetylglucosamine residue. High-pH anion-exchange chromatography analysis during exponential growth demonstrated the presence of RNase B-derived glycans in the culture supernatant, indicating the presence of an endoglycosidase activity. The free glycans were eluted with the same retention times as those generated by the action of Streptomyces plicatus endo-beta-N-acetylglucosaminidase H on RNase B. The cleavage specificity was confirmed by MALDI-TOF analysis of the free glycans, which showed glycan species containing only one N-acetylglucosamine residue. No free glycans were detectable after 5 h of bacterial growth, and we have subsequently demonstrated the presence of mannosidase activity in E. faecalis, which releases free mannose from RNase B-derived glycans. We propose that this deglycosylation of glycoproteins containing high-mannose-type glycans and the subsequent degradation of the released glycans by E. faecalis may play a role in the survival and persistence of this nosocomial pathogen in vivo.

Carbohydrate Sequence↗
PubMed1999

The evolution of quantitatively responsive cooperative trade.

The iterated Prisoner's Dilemma reflects the essence of repeated cooperative interactions with selfish incentives. However, the classical form of this game assumes that individuals either cooperate or defect, whereas in practice different degrees of cooperation are usually possible. To overcome this limitation, we present a model of alternating cooperative trade in which individuals controlled the costs they incurred in benefiting their partners. Since the range of possible strategies is enormous, competitively successful solutions were identified using a genetic algorithm, a powerful search technique in which good performers are iteratively selected and recombined from an initial "strategy soup". Beginning with a population of asocial individuals, altruistic behaviour readily emerged. Like the pre-defined strategy of "Raise-the-Stakes", the emerging strategies evolved protection from cheats by investing relatively little in strangers and subsequently responding quantitatively to a partner's altruism. Unlike "Raise-the-Stakes", they began trading relations at intermediate levels and, when the benefit-to-cost ratio of cooperation was relatively low, mean investment was considerably below the maximum level. Our approach is novel in allowing us to predict not just whether cooperation will occur, but how cooperative individuals will be, in relation to factors such as the number of rounds and the cost effectiveness of cooperative trade.

Altruism↗
PubMed1999

The pattern of change in salivary immunoglobulins and antibodies to S. mitis and S. oralis in children undergoing bone marrow transplantation: use of an indirect method of assessment.

The objective of this study was to assess the pattern of change in salivary immunoglobulins and antibodies to S. mitis and S. oralis in 23 children following allogeneic bone marrow transplantation and their matched controls. To overcome the difficulty of obtaining a sufficient quantity of whole saliva from very young, sick children saliva was collected in a 5-ml oral rinse of sterile normal saline. It was not possible to measure the volume of whole saliva in each rinse and the concentration of the salivary immunoglobulins and bacterial antibodies were estimated from 1 ml of oral rinse. Despite these shortcomings a pattern of change in the mean concentrations of total salivary IgA, secretory IgA, antibodies to S. mitis and S. oralis and total IgG at specific event- related times during the transplantation period has been demonstrated. There was a significant increase in the concentration of salivary IgG 7 days post-transplantation, followed by significant decreases in total salivary IgA, secretory IgA and antibodies to S. mitis after recovery of the peripheral neutrophil count above 0.5 x 10(9). The concentrations of total IgA and antibodies to S. oralis was significantly greater in the transplant group 119 days post-transplantation.

Antibodies, Bacterial↗
PubMed1999

An open trial comparing isradipine with hydralazine and methyl dopa in the treatment of patients with severe pre-eclampsia.

Placental blood flow is decreased in pre-eclampsia and is worsened by decreasing blood pressure. Hydralazine, which causes vasodilatation, does not affect placental bed vessels. Calcium channel blockers (like isradipine) are vasodilators that do affect placental bed vessels and should improve blood flow even while decreasing blood pressure. The aim of the study was to determine if isradipine (parenteral and oral) was better than parenteral hydralazine and oral methyl dopa in severe pre-eclampsia in achieving better control of blood pressure. The study was a prospective randomised trial performed at The University Hospital of the West Indies. The sample consisted of 39 women with severe pre-eclampsia. Variables examined consisted of blood pressure before and after treatment, the increment in gestational age at delivery related to treatment, fetal Apgar score and birth weight. There were no significant differences in any of these variables between the two groups. Isradipine was as effective as hydralazine in reducing maternal blood pressure and in prolonging pregnancy.

Clinical Trial↗
PubMed1999

Screening for familial intracranial aneurysm: resource implications.

In this descriptive study, we estimate the resource implications of screening 18-65 year-old first degree relatives of patients with a first degree family history of intracranial aneurysm (IA). A postal survey of 374 patients who underwent operative clipping of IA between July 1994 and June 1997 was performed, enquiring about first degree family history of IA and first degree family structure. The response rate was 68.2% (255/374). Thirty-five out of 255 patients (14.0%) reported IAs in first degree relatives and 21 (8.2%) in second degree relatives giving a total of 57 (22.0%) with a reported family history. The average number of screenable relatives currently living in Ireland was 5.6 per high-risk family. Assuming a national prevalence of 0.45% for ruptured IA, these data give a point prevalence for high-risk families of 816 in the Republic of Ireland (1996 census population 3.6 x 10(6). Thus, the number of currently screenable relatives (5.6 per family) is 4814. A 15% yield has previously been reported from screening of first degree relatives in Northern Ireland. A national screening programme should thus detect over 700 individuals with asymptomatic IAs. The time required to screen the screenable population once would be 2.3 years by digital subtraction angiography (DSA) and 1.1 years by magnetic resonance angiography (MRA). In order to detect de novo aneurysms, screening has been suggested in this suspect population at 6-monthly to 5-yearly intervals after the initial study. In the absence of a biological marker, the results of our survey suggest that screening for familial IA disease would pose a significant logistical burden and have major financial implications for health care services.

Adolescent↗
PubMed1999

Age effects and health appraisal: a meta-analysis.

OBJECTIVE: The purpose was to clarify the effects of methodological variables in the research on age differences in self-rated health and specifically the effects of: (a) the item type used to solicit the appraisal, (b) the approach to sampling, and (c) the criteria for assembling the age groups for study. METHODS: Studies differing on these dimensions were compared using meta-analytic techniques. Seventeen usable samples were grouped according to the age comparisons--seven compared "young" and "old" samples while ten compared "young-old" and "old-old" groups. RESULTS: The results failed to support the frequently reported health optimism of old-old samples when compared with young-old. Further, the findings suggest that the item type used in eliciting the rating of health may be instrumental in the respondent's appraisal process. For instance, use of the age-comparative item tends to favor "old" groups when compared to young, whereas the global health item has an effect in the other direction. Effect size was also related to a study's sampling procedure and to the method used in assembling groups (i.e., age ranges used to represent young and old). DISCUSSION: Practical implications and areas of needed research are discussed.

Adolescent↗
PubMed1999

Shoulder dystocia.

Explore the source record for details and available documents.

Cesarean Section↗
PubMed1999

Multicenter laboratory validation of susceptibility testing of Mycobacterium tuberculosis against classical second-line and newer antimicrobial drugs by using the radiometric BACTEC 460 technique and the proportion method with solid media.

In a large multicenter study involving six major study sites in the United States, Canada, and Europe, the susceptibilities of 272 Mycobacterium tuberculosis strains to classical second-line antituberculosis (anti-TB) drugs (capreomycin, cycloserine, ethionamide, and kanamycin) and newer compounds (amikacin, clofazimine, ofloxacin, and rifabutin) were determined by the radiometric BACTEC 460 procedure and the conventional proportion method on Middlebrook 7H10 agar. Previously established critical concentrations for classical second-line anti-TB drugs were compared with several concentrations in liquid medium to establish equivalence. MICs of newer compounds determined in liquid medium were either the same or up to four times lower than those determined in agar medium. After establishing critical concentrations (breakpoints) in the extended testing of clinical isolates, we obtained an excellent overall correlation between the two systems, with no errors with amikacin, kanamycin, and ofloxacin and very few major or very major errors with the other drugs; however, for cycloserine, no breakpoint concentration could be recommended due to repeatedly inconsistent results by both methods. Based on these data we conclude that the BACTEC 460 procedure is a simple and rapid method requiring 4 to 8 days on average to generate accurate antimicrobial susceptibility testing (AST) results for eight anti-TB drugs other than those considered primary ones. These data not only fill a major gap of knowledge regarding the critical test concentrations of secondary anti-TB drugs but also provide a baseline for future evaluations of M. tuberculosis AST with the more recently developed, nonradiometric broth-based culture systems.

Anti-Bacterial Agents↗
PubMed1999

Plasma vasopressin and response to treatment in primary nocturnal enuresis.

AIMS: To examine the relation between nocturnal vasopressin release and response to treatment with the vasopressin analogue 1-desamino-8-D-arginine vasopressin (DDAVP) in children with primary monosymptomatic nocturnal enuresis. DESIGN: Children were recruited from a specific enuresis clinic and entered into a defined treatment programme. Nocturnal vasopressin concentrations were measured every 15 minutes over a four hour period during overnight admission. RESULTS: Sixty seven children were eligible for entry into the study, 35 of whom agreed to overnight sampling. There was a quadratic relation between mean plasma AVP and response to treatment with DDAVP, with very high or very low concentrations being unresponsive. Plasma AVP profiles ranged from low concentrations with little variability to high concentrations with wide variability. CONCLUSION: The ability to respond to DDAVP is related to endogenous AVP production and is influenced by neuronal patterning in early infancy. The best predictors of success with treatment were a past history of breast feeding, mean nocturnal AVP concentration, and the height of the child. The response was adversely affected by poor weight at birth and poor linear growth. The study suggests differing causes of nocturnal enuresis related to different patterns of AVP release.

Adolescent↗
PubMed1999

The cost of radiotherapy as a function of facility size and hours of operation.

Against a background of constant or decreasing budgets, this study was undertaken to investigate the economic effects of changes in selected operational parameters within a radiation treatment programme. Using financial data from the Northeastern Ontario Regional Cancer Centre and a recognized staffing model, a commercial spreadsheet has been used to calculate the cost of an 18 fraction course of radiotherapy, including all the major preparatory processes such as simulation and treatment planning. Using the spreadsheet, and on the basis of explicit and reasonable assumptions, the cost of radiotherapy has been calculated as the facility size (i.e. equipment complement) and hours of operation are varied. Based on the assumptions used, the cost of radiotherapy in a facility treating less than about 1600 patients per year starts to rise. At 400 patients per year, a course costs approximately 50% more than at 1600 patients per annum. Extended hours of operation do not appear to generate significant, if any, savings when realistic assumptions about machine lifetime and overtime payments are made. Using a spreadsheet to simulate changes in a radiation treatment programme can be an important decision-making tool, as the effects of changes in operating parameters can be demonstrated.

Health Care Costs↗