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Biomedical subjects

D M Robinson

Publications and source records attributed to D M Robinson.

At least 19 recordsLinked to original sources
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↗
PubMed1988

A monoclonal antibody for the specific diagnosis of plague.

A stable mouse-cell hybridoma was obtained that secretes an IgA monoclonal antibody reactive with the fraction 1 (F1) envelope antigen of Yersinia pestis. Titres of the antibody typically ranged from 1:32 768 to 1:65 536 in mouse ascitic fluids.The monoclonal antibody formed a line of precipitation when run against F1 antigen in Ouchterlony gel diffusion tests. In tests of 235 strains of Y. pestis, lines of identity occurred between the precipitates formed with a solution of purified F1 antigen and the F1 antigen produced by the plague strains. No precipitates formed for 65 strains that were incapable of elaborating F1 antigen. Specificity of the monoclonal antibody for strains of Y. pestis producing F1 was also indicated by negative results for 50 yersinia strains other than Y. pestis tested by an ELISA that used the antibody to capture antigen.Experiments to determine the shelf-life of the antibody were conducted over 3-4 years. When the monoclonal antibody was freeze-dried in vials, titre was retained for three years when the vials were stored at -70 degrees C but only for two months when they were stored at ambient temperatures. When the antibody was freeze-dried in wells of ELISA plates, sensitivity of the plates for capture of F1 antigen was preserved for four years when the plates were stored at -70 degrees C compared with two weeks for plates stored at room temperature. When a solution of the antibody was sealed in wells of ELISA plates and refrigerated at 4 degrees C, reactivity of the antibody and sensitivity of the plates were retained for a year.Alternatives for the application of this monoclonal antibody in ELISA and other plague diagnostic procedures are discussed.

Animals↗
PubMed1986

Global survey of antibody to Hantaan-related viruses among peridomestic rodents.

A global serological survey of rodents was conducted to determine the distribution and prevalence of antibody to Hantaan-related viruses, which are the causative agents of haemorrhagic fever with renal syndrome (HFRS) in man. Over 1700 rodent sera from more than 20 sites worldwide were examined by immunofluorescent antibody assay. High-titred positive sera were further tested by plaque reduction neutralization tests with prototype Hantaan virus and urban rat-associated Hantaan-like virus. Antibody-positive rodents were found in most, but not all, sites sampled. The highest antibody prevalence rates were found in Baltimore, MD, USA and Bélem, Brazil, and Rattus norvegicus was the species most often found positive. Bandicota indica and B. bengalensis, species previously not recognized as hosts of hantaviruses, were also positive. Neutralization tests detected antibody in Rattus sera specific for urban rat-associated Hantaan-like virus, but failed to establish the specificity of antibody in Bandicota sera. These results indicate that Hantaan-related viruses exist beyond the currently recognized boundaries of HFRS in man and suggest that human HFRS-like disease might be occurring in other areas of the world where rodent-human contact is common.

Africa↗
PubMed1979

Hypothalamic-pituitary responses to high concentrations of gonadal steroids in a three-month-old infant with a feminizing gonadal stromal tumor.

A 3-month-old female infant feminized by an ovarian stromal tumor is presented. Clinicopathologic aspects of such tumors occurring in infancy are discussed. In addition, the evaluation of hypothalamic-pituitary function preoperatively and postoperatively are presented. In the preoperative, high-steroid environment, both basal and stimulated secretion of follicle-stimulating hormone (FSH) was suppressed. Secretion of luteinizing hormone (LH) was normal. Following surgical castration, stimulated secretion of both gonadotropins clearly increased. These findings suggest an active but less sensitive negative feedback mechanism for FSH than for LH during infancy, i.e., high concentrations of gonadal steroids are necessary to maximally suppress FSH secretion while normal steroid concentrations appear to maximally suppress LH secretion. Developmental changes in hypothalamic-pituitary sensitivity to negative feedback controls are discussed in light of these findings.

Female↗
PubMed1979

Antigenic analysis by direct immunofluorescence of 114 isolates of Rickettsia tsutsugamushi recovered from febrile patients in rural Malaysia.

One hundred and fourteen Rickettsia tsutsugamushi isolates, recovered from febrile patients in central Peninsular Malaysia, were antigenically analyzed by direct immunofluorescence using eight prototype strains. Twenty-nine antigenic types were detected. The TA763, TA716, Karp and TA686 strains were the most common and occurred singly or in combination with each other or other strains in 86% of the isolates.

Antigens, Bacterial↗