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Biomedical subjects

D M Robinson

Publications and source records attributed to D M Robinson.

At least 37 records · Page 2Linked to original sources
PubMed1997

Guidelines for the treatment of Helicobacter pylori in the pediatric population.

Several factors including long-term eradication of the organism, cost, compliance, and adverse event profile should be considered for treating H. pylori infection in pediatric patients. Triple therapy with bismuth, tetracycline, and metronidazole is considered the gold standard for adult patients; however, tetracyclines are not recommended in children younger than 8 years due to the potential for tooth discoloration and alterations in bone growth. Dual and shorter duration of therapy should be evaluated in children with H. pylori. The new dual therapy omeprazole/clarithromycin regimens approved by the Food and Drug Administration for adults may be considered as an alternative for children when concerns include the use of salicylates or allergy to beta-lactams. Although the dosage of omeprazole in pediatric patients has not been established (no pediatric formulation exists), clarithromycin is available for use in pediatric patients. However, these drugs cannot be recommended for children with H. pylori until additional studies in this population are available. Based on the available data, aminopenicillin/bismuth or aminopenicillin/tinidazole combinations appear to be effective in eradicating H. pylori in children. Amoxicillin 50 mg/kg/d plus bismuth subsalicylate (< 10 y, 262 mg; > 10 y, 525 mg qid) or bismuth subcitrate (< 12 y, 120 mg; > 12 y, 240 mg bid) can be used for 6 weeks. The bismuth dosages represented above were those used in various studies. It should be realized, however, that a definitive dosage of bismuth subsalicylate for children in the treatment of H. pylori has not been established. The adult dosage of bismuth subsalicylate for the eradication of H. pylori is the same as that used for prophylaxis in diarrhea (525 mg qid). When dosage of this agent is unknown (particularly for the treatment of very young children), the use of established dosages for prophylaxis in diarrhea may be considered for treating H. pylori. Additionally, bismuth subsalicylate should be used with caution in children with suspected viral infections (i.e., to prevent Reye's syndrome) or those receiving concurrent therapy with interacting drugs. If available, tinidazole 20 mg/kg/d can be used with amoxicillin 50 mg/kg/d for 6 weeks to treat children infected with H. pylori.

Adolescent↗
PubMed1994

Increased peak oxygen consumption of trained muscle requires increased electron flux capacity.

The importance of the training-induced increase in mitochondrial capacity in realizing the increase in maximal O2 consumption (VO2max) of trained muscle was evaluated using an isolated perfused rat hindlimb preparation at a high blood flow (approximately 80 ml.min-1.100 g-1) during tetanic contractions. Rats trained for 8-12 wk by treadmill running exhibited an approximately 25% increase in muscle VO2max (5.62 +/- 0.31 to 7.06 +/- 0.64 mumol.min-1.g-1), an increase in mitochondrial enzyme activity (approximately 70% for cytochrome oxidase and approximately 55% for NADH cytochrome-c reductase), and an increase in tissue capillarity (14%) that is expected to increase the O2 exchange capacity of the tissue. Muscle VO2max of sedentary (n = 34) and trained (n = 30) animals was determined, and electron transport capacity was acutely managed with myxothiazol, a tight-binding inhibitor of complex III. Inhibition of complex III was similar among 1) the low- and high-oxidative fibers and 2) the superficial and deep mitochondrial populations within muscle. Inhibition of NADH cytochrome-c reductase activity resulted in reductions in muscle VO2max with similar dose responses (mean effective dose of approximately 0.2 microM) of myxothiazol added to the perfusion medium. The extraction of O2 by the contracting muscle decreased as VO2max declined. The increase in muscle VO2max observed in the muscle of trained animals was eliminated when its electron transport capacity was reduced to that observed in normal sedentary rat muscle. Thus, the exercise-induced adaptation of an increased muscle mitochondrial content appears to be essential for trained muscle to exhibit its increased O2 flux capacity. The results of the present experiment illustrate the importance of mitochondrial adaptations in muscle remodeled by exercise training.

Animals↗
PubMed1994

Health information privacy: without confidentiality.

The relation between privacy and confidentiality is critically discussed. The need to be able to process data for epidemiology and management is presented. Too often the protection of privacy is considered to be a synonym of denying access to the patient's data. The function of the Canadian National Institute for Health Information is mentioned as as example of a wider trend to have a national focal point in the development of national databanks and for administering health information networks. Protection of privacy is considered to be the most important threat to the effectiveness of such networks.

Canada↗
PubMed1993

Predictors of attainment in rhythmic sportive gymnastics.

Correlates of attainment in rhythmic sportive gymnastics (RSG) were investigated in a cross-sectional study of 106 female gymnasts aged 7-27 years. Physical attributes were obtained by anthropometry and from tests of flexibility, leg power, maximum oxygen uptake and visuo-motor proficiency. Training and psychological measures were derived from self-administered questionnaires that included the Leadership Scale for Sport, Psychological Skills Inventory for Sport, General Health Questionnaire, Sport Competition Anxiety Test, and several questions on sport motivation and enjoyment. Attainment was expressed as competition grade level and mean performance score in 4 competitions. The best correlates of attainment were cumulative and current training time (r = 0.84-0.53). Age, lean body mass and composite measures of flexibility, leg power and visuo-motor proficiency were also significant correlates of attainment (r = 0.69-0.29), as were coach democratic and coach social behaviours (r = 0.41-0.28). The significant positive psychometric correlates of attainment were mental preparation, motivation by creativity, and several dimensions of enjoyment (r = 0.35-0.26); significant negative correlates were recent anxiety-depression and enjoyment of training (r = -0.34-(-)0.32). No previous study has identified the relative contributions of such a comprehensive range of physical, psychological and training measures to performance of a sport.

Adolescent↗
PubMed1992

Effects of a physical conditioning programme on asthmatic patients.

AIMS: to determine whether moderate/severe asthmatics can improve their physical fitness using standard commercial gymnasium fitness programmes and to examine the effect on their asthma. METHODS: eight moderate to severe asthmatics and seven nonasthmatic controls were tested before and after 12 weeks indoor circuit training at a commercial gymnasium. The aerobic fitness of both groups was assessed before, during and after the conditioning period. Measures of asthma severity, habitual activity levels and psychological status were also assessed. RESULTS: peak oxygen uptakes increased significantly in both asthmatics and controls, mean and 95% confidence interval (95% CI) values rising from 27.5 (21.9-33.0) to 31.3 (23.5-39.1) and 29.2 (25.9-32.5) to 32.2 (28.5-35.9) mL.min-1.kg-1 respectively. Following training, minute ventilation at high workloads was significantly reduced in the asthmatic subjects. In all participants subjective ratings of the ability to perform physical tasks was significantly increased as was the amount of habitual physical activity reported. Although the asthmatics' bronchial responsiveness to histamine, medication usage and symptom scores did not change, the daily recorded peak expiratory flow (PEFR) increased slightly, and its variability declined. CONCLUSIONS: these findings demonstrate that with proper management severe asthmatics can engage in vigorous circuit training and enjoy the health benefits of regular exercise.

Adult↗
PubMed1992

Implant superstructures: a comparison of ultimate failure force.

Because of reported prosthodontic failures, alternative implant abutments and screws with suggested strength superiority have been manufactured. However, little quantitative data are available to support these claims. This study compared the force necessary to cause failure in many of the more commonly used implant and abutment combinations. An 18-mm cantilever test prosthesis was constructed for each system and loaded on an MTS machine until failure occurred (n = 5 for each sample). The mean failure forces ranged from 1.22 to 17.23 kg. The failure force and location of failure for each individual system are reported.

Analysis of Variance↗
PubMed1991

Monoenergetic approximately of a polyenergetic beam: a theoretical approach.

There exist numerous occasions in which it is desirable to approximate the polyenergetic beams employed in radiation therapy by a beam of photons of a single energy. In some instances, commonly used rules of thumb for the selection of an appropriate energy may be valid. A more accurate approximate energy, however, may be determined by an analysis which takes into account both the spectral qualities of the beam and the material through which it passes. The theoretical basis of this method of analysis is presented in this paper. Experimental agreement with theory for a range of materials and beam qualities is also presented and demonstrates the validity of the theoretical approach taken.

Cobalt Radioisotopes↗
PubMed1991

Training intensity of elite male distance runners.

To quantify training intensity in 13 nationally ranked male distance runners, training heart rates, environmental factors, and motivational factors were recorded throughout a 6-8 wk period of normal training. Variation in motivational and environmental factors such as intended effort, terrain, and running with companions altered training session mean heart rates by up to 4.min-1 (standard deviation). Heart rates and blood lactate concentrations, recorded in a series of steady-state treadmill runs, were used to convert training session mean heart rates to mean training speeds (TS) and to derive a measure of the anaerobic threshold (AT, the treadmill speed at a blood lactate concentration of 4 mmol.l-1). TS (15.6 +/- 1.4 km.h-1, mean +/- SD) was considerably lower than AT (20.2 +/- 1.1 km.h-1) in all subjects (P less than 0.001). Relative TS (TS expressed as a fraction of AT) differed significantly (P less than 0.001) between subjects and correlated significantly with the distance of the event for which the subject was training (r = 0.59, P less than 0.05). Relative TS may therefore be determined by the subject's or coach's perception of the appropriate intensity for the event. If the AT is the optimum training intensity, these subjects have considerable scope for improvement.

Adult↗
PubMed1990

An analytic approach to optimized retracted missing tissue compensators.

The introduction of an attenuating medium into a photon beam serves both to reduce the intensity of the primary beam and to create secondary radiation due to scatter. When retracted missing tissue compensators are employed to compensate for irregular surface contour or internal inhomogeneities, they are often fabricated without regard to the scattered radiation that they introduce into the system. The study of a mathematically describable conical geometry has clearly demonstrated the need for improved compensator design. Experimental results obtained with this geometry can be reproduced with good agreement, using theoretical calculations based on primary and first order scattered radiation. This method of analysis may be extended to predict the shape of a compensator which will produce an optimized dose distribution at a given depth in a phantom, equivalent to that which would be obtained when an irregular surface is filled with unit density material (bolus), producing a flat surface. An optimized compensator was constructed based on these theoretical considerations and excellent agreement was observed between theory and experiment. Dramatic improvement in the restoration of bolus dose is obtained with this optimized compensator. Finally, an anthropomorphic phantom of the neck region has been constructed and the performance of a compensator designed according to current clinical methods for this geometry has been evaluated. The performance of an optimized compensator specific to this geometry is presented and good agreement between theoretical predictions and experimental results is observed. Dramatic improvement in bolus dose restoration over that obtained with the clinically designed compensator is realized.

Humans↗
PubMed1989

HLA class II typing using oligonucleotide probes.

A DQ beta locus-specific oligonucleotide probe is used to identify DQ beta alleles present in six insulin-dependent diabetes mellitus (IDDM) multiplex families. Results of genotyping using this technique agree with those from cDNA probes and are often clearer. Allele-specific oligonucleotide probes for the DR beta locus are used to identify subtypes (Dw4 and Dw14) of the DR4 specificity in five IDDM multiplex families. This distinction cannot be made with available cDNA probes.

Blotting, Southern↗
PubMed1989

HLA DQ beta 3.2 identifies subtypes of DR4+ haplotypes permissive for IDDM.

The HLA class II-related susceptibility to type I insulin-dependent diabetes mellitus (IDDM) is examined in 94 multiplex families sorted by the presence or absence of a DR4+ haplotype in at least one diabetic family member. The families with DR4+ haplotypes are then sorted by the presence or absence of a DR4-linked DQ beta 3.2 allele. Further analysis assumes each multiplex family to represent a single diabetic genetic event and identifies the HLA class II haplotype(s) present in all affected members. The DQ beta 3.2 allele is present in over 95% of the multiplex families where DR4+ haplotypes segregate with IDDM, implying a major permissive role in determining susceptibility to IDDM.

Diabetes Mellitus, Type 1↗
PubMed1989

Limitations of retracted missing tissue compensators: an experimental analysis.

The introduction of an attenuating medium into a photon beam serves both to reduce the intensity of the primary beam and to create secondary radiation due to scatter. When retracted missing tissue compensators are employed to compensate for irregular surface geometry or internal inhomogeneities they are almost always fabricated without regard to the scattered radiation that they introduce to the system. Analysis of such a retracted compensator designed for use with an anthropomorphic phantom reveals an inability to provide true compensation. Subsequent analysis of a mathematically describable conical geometry demonstrates the need for improved compensator design.

Humans↗