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Biomedical subjects

R A Cooper

Publications and source records attributed to R A Cooper.

At least 163 records · Page 9Linked to original sources
PubMed1992

Maximal exercise response of paraplegic wheelchair road racers.

The maximal metabolic responses of 11 paraplegic wheelchair road racers were evaluated with 2 wheelchair exercise protocols: increasing speed and increasing resistance. The maximal heart rates, minute ventilations and oxygen uptakes were similar for the 2 tests, indicating that either protocol is suitable for maximal wheelchair dynamometer exercise tests for groups. The resulting data were then compared to published data on maximal arm exercise by athletic and non athletic paraplegics and ambulatory males of the same age group. The combined mean values for both exercise tests of maximal oxygen consumption rate (VO2max = 37.4 ml/kg/min), minute ventilation (VE = 109.4 l/min), respiratory exchange quotient (RQmax = 1.18) and heart rate (187 beats/min) are in the mid range of reported data on wheelchair athletes. The mean RQ and heart rate values were similar to those achieved by ambulatory individuals performing maximal exercise tests. The mean VO2max of 37.4 ml/kg/min in our subjects is comparable to that achieved by sedentary ambulatory males of this age group. The data and the comparison to published data suggest several conclusions: in some parameters elite male paraplegic road racers have maximal values similar to those of ambulatory males, and in others they have maximal values substantially lower than might be expected; there is considerable variability among paraplegics in the metabolic responses to maximal exercise, most likely related to differences in cardiovascular fitness; and paraplegics can improve their cardiovascular fitness by training.

Adult↗
PubMed1992

Differential development and reproduction of the German cockroach (Dictyoptera: Blattellidae) on three laboratory diets.

Development of nymphs and oocyte maturation in adults were examined in Blattella germanica (L.) reared on three commercial diets. Nymphs fed rat food developed significantly faster than nymphs fed two commercial dog foods. Similarly, oocytes matured more quickly in adult females that were raised on rat food than in females raised on dog food. Nymphal development and oocyte maturation were slower in insects that were fed whole dog food pellets than in insects fed ground dog food, suggesting that grinding the diet diminishes a mechanical barrier in whole dog food pellets. Comparisons of processed canine food and unprocessed canine food indicated that diets were significantly inferior after the steam extrusion process. Rat food is normally not subjected to such conditions and both processed and unprocessed rat food are equally suitable for B. germanica. The significance and implications for comparative studies with cockroaches are discussed.

Animal Feed↗
PubMed1992

Alkyl and aryl neoalkanamides: highly effective insect repellents.

Alkyl and aryl neoalkanamides with a total carbon number between 11 and 14, or within a molecular weight range between 185 and 227, were highly effective repellents of male German cockroaches, Blattella germanica (L.). Comparison with known repellents showed that members of this unique family of secondary amides are among the most effective and long-lasting repellents of cockroaches examined to date. In assays with females and nymphs of the German cockroach, male American cockroaches, Periplaneta americana (L.), and carpenter ant workers, Camponotus pennsylvanicus (De Geer) methyl neodecanamide, propyl neodecanamide, and methyl neotridecanamide were found highly repellent. Because of their broad spectrum of activity, longevity, and safety, these compounds, along with several other members of this family, have important applications as repellents of nuisance pests and of arthropods of public health importance.

Amides↗
PubMed1992

Racing wheelchair roll stability while turning: a simple model.

Wheelchair racing is an important modality in the rehabilitation of people with mobility impairments; thus, it plays a significant role in the lives of many wheelchair users. This paper presents simple roll stability analyses for three- and four-wheeled rider/racing wheelchair systems during turning maneuvers. The results suggest that three-wheeled systems may be less stable than four-wheeled systems under certain circumstances. On the other hand, under certain circumstances, four-wheeled systems could be less stable than three-wheeled systems as well. Further study is required to include human factors in determining the optimal relation between stability and controllability.

Biomechanical Phenomena↗
PubMed1992

The contribution of selected anthropometric and physiological variables to 10K performance of wheelchair racers: a preliminary study.

The purpose of this study was to determine the relationship between selected anthropometric and physiological variables and 10K time. Eleven male wheelchair athletes with spinal cord injuries in training for national competition performed continuous progressive exercise tests on a wheelchair ergometer to determine maximal metabolic and cardiorespiratory values. Anthropometric data were also collected. The laboratory data were analyzed for correlation with the best 10K time of each subject during the test period. The subjects averaged 27 min 30 sec for their 10K races, 2.49 L.min-1 for VO2max and 35 percent for maximal gross mechanical efficiency during submaximal exercise. Speed at peak oxygen consumption (r = -0.66), gross mechanical efficiency (r = -0.56), and body density (r = -0.57) was found to be significantly (p less than 0.10) correlated with 10K time. The results show very little correlation between VO2max and 10K time (r = 0.02). Further study is indicated for the relationship between gross mechanical efficiency, speed at maximal oxygen consumption, body density, and 10K time; these variables may be useful in evaluating training programs for improving race performance.

Adult↗
PubMed1992

The inferior capsular-shift procedure for multidirectional instability of the shoulder.

Thirty-eight patients (forty-three shoulders) who had disabling multidirectional instability of the shoulder were managed with an inferior capsular-shift procedure through an anterior approach. All of the patients were followed for a minimum of two years. The postoperative range of motion of the shoulders was well maintained. The mean forward elevation was 172 degrees; external rotation, 77 degrees; and internal rotation, to the level of the eighth thoracic vertebra. Four patients (four shoulders) had recurrence of symptomatic and disabling multidirectional instability, but thirty-nine (91 per cent) of the shoulders continued to function well with no instability. Nine patients (24 per cent) continued to have episodes of apprehension, which correlated with the residual inferior and posterior translations found at the postoperative physical examination. Thirty-four patients (thirty-nine shoulders) stated that they were subjectively satisfied with the status of the shoulder, but four patients, in whom the instability had recurred, were not satisfied. Thirty-seven (86 per cent) of the shoulders were judged to have been improved by the procedure, the initial postoperative stability had been maintained, and the result had not deteriorated with time. Six shoulders, however, including the four with recurrent instability, were thought by the patient to have deteriorated with the increased duration of follow-up. It was our experience that if non-operative treatment of multidirectional instability of the shoulder failed, the inferior capsular-shift procedure provided satisfactory objective and subjective results. Failures and recurrences of symptomatic instability occurred early in the postoperative period. There appeared to be no deterioration of the results with follow-up to seventy-one months.

Adolescent↗
PubMed1992

Juvenile hypertrophy presenting as a discrete breast mass.

Juvenile hypertrophy of the breast usually presents as diffuse enlargement of the breasts in young women. The authors describe a patient in whom hypertrophy presented as a discrete mass, which was both visible in mammograms and palpable.

Adult↗
PubMed1991

Metastatic carcinoma to the male breast.

A case of metastasis to the male breast from prostate carcinoma is reported. For proper treatment, it is important to differentiate primary from metastatic tumours. Prostate-specific antigen screening should be strongly considered in all breast masses seen in patients with known prostatic carcinoma. One cannot assume that breast enlargement in these patients is solely due to oestrogen-induced gynecomastia.

Adenocarcinoma↗
PubMed1991

Dual technique for preoperative localization of nonpalpable breast lesions.

The combination of guide wire and dye techniques for preoperative localization of nonpalpable breast lesions is superior to either technique alone. The dye acts as a backup in the event of migration, transection or removal of the wire, which has occurred in 2 (1.3%) of 154 localizations of breast lesions at the author's institution.

Biopsy, Needle↗
PubMed1990

Subcloning and nucleotide sequence of the 3,4-dihydroxyphenylacetate (homoprotocatechuate) 2,3-dioxygenase gene from Escherichia coli C.

A cloned gene encoding the Escherichia coli C homoprotocatechuate (HPC) dioxygenase, an aromatic ring cleavage enzyme, was used to produce large amounts of the protein. Preparations of E. coli C HPC dioxygenase, whether expressed from the cloned gene or produced by the bacterium, lost activity very rapidly. The pure protein showed one type of subunit of Mr 33,000. The first 21 N-terminal amino acids were sequenced and the data used to confirm that the open reading frame of 831 bp, identified from the nucleotide sequence, encoded HPC dioxygenase. Comparison of the derived amino acid sequence with those of other extradiol and intradiol dioxygenases showed no obvious similarity to any of them.

Amino Acid Sequence↗
PubMed1990

Purification, some properties and nucleotide sequence of 5-carboxymethyl-2-hydroxymuconate isomerase of Escherichia coli C.

As part of an investigation into the evolution of catabolic pathway enzymes a cloned gene encoding the Escherichia coli C 5-carboxymethyl-2-hydroxymuconate (CHM) isomerase, an enzyme of the homoprotocatechuate catabolic pathway, was used to produce large amounts of the protein. The isomerase was purified to homogeneity and some of its properties determined. The reaction occurred optimally at pH 7.6 and the specificity constant was 5.8 x 10(5) M-1.s-1 with CHM and 6.0 x 10(2) M-1.s-1 with 2-hydroxyhepta-2,4-diene-1,7-dioate, the substrate of a second isomerase in the pathway. The pure protein showed one type of subunit of Mr 14,000 whilst the molecular mass of the native enzyme was 30,000, suggesting that it was a dimer of identical subunits. The first 19 N-terminal amino acids were sequenced and the data used to confirm that the open reading frame of 378 bp, identified from the nucleotide sequence, encoded the CHM isomerase.

Amino Acid Sequence↗
PubMed1990

Catabolism of 3-hydroxybenzoate by the gentisate pathway in Klebsiella pneumoniae M5a1.

Growth of Klebsiella pneumoniae M5a1 on 3-hydroxybenzoate leads to the induction of 3-hydroxybenzoate monooxygenase, 2,5-dihydroxybenzoate dioxygenase, maleylpyruvate isomerase and fumaryl-pyruvate hydrolase. Growth in the presence of 2,5-dihydroxybenzoate also induces all of these enzymes including the 3-hydroxybenzoate monooxygenase which is not required for 2,5-dihydroxybenzoate catabolism. Mutants defective in 3-hydroxybenzoate monooxygenase fail to grow on 3-hydroxybenzoate but grow normally on 2,5-dihydroxybenzoate. Mutants lacking maleylpyruvate isomerase fail to grow on 3-hydroxybenzoate and 2,5-dihydroxybenzoate. Both kinds of mutants grow normally on 3,4-dihydroxybenzoate. Mutants defective in maleylpyruvate isomerase accumulate maleylpyruvate when exposed to 3-hydroxybenzoate and growth is inhibited. Secondary mutants that have additionally lost 3-hydroxybenzoate monooxygenase are no longer inhibited by the presence of 3-hydroxybenzoate. The 3-hydroxybenzoate monooxygenase gene (mhbM) and the maleylpyruvate isomerase gene (mhbI) are 100% co-transducible by P1 phage.

Chromatography, Ion Exchange↗
PubMed1990

Concentrations of glycosaminoglycans in synovial fluids and their relation with immunological and inflammatory mediators in rheumatoid arthritis.

The dimethylmethylene blue assay showed higher concentrations of glycosaminoglycans in many synovial fluids from patients with rheumatoid arthritis (RA) than in autologous sera or sera or synovial fluids from normal subjects. These results were taken to suggest that the glycosaminoglycans in RA synovial fluid were abnormally raised and derived from cartilage. To discover what stimulated such glycosaminoglycan release in RA joints relations were sought between synovial fluid concentrations of glycosaminoglycans and immunological and inflammatory mediators. It was shown that RA synovial fluid glycosaminoglycan concentrations correlated with synovial fluid C3d concentrations but not with synovial fluid rheumatoid factor concentrations, polymorphonuclear leucocyte numbers, myeloperoxidase concentrations, or the ability of the synovial fluids to release free radicals from normal polymorphonuclear leucocytes. A correlation was found between synovial fluid C3d and interleukin 1 concentrations as judged by both lymphocyte activating factor activity and immunoassay, but no significant correlation was detected between interleukin 1 and glycosaminoglycan concentrations. It is suggested that in the rheumatoid joint locally produced cytokines, in addition to interleukin 1, together stimulate glycosaminoglycan release from cartilage and render it vulnerable to attack by other processes.

Adult↗
PubMed1990

A systems approach to the modeling of racing wheelchair propulsion.

This paper presents a systems model for racing wheelchair propulsion. Recently, an interest has developed in computer and mathematical models of racing wheelchair propulsion with the goal of improving performance and efficiency. The model in this paper is first presented in block diagram form and later described in greater detail. Equations are presented that describe the motion of a racing wheelchair on the road/track and an inertial roller system, as well as kinematic equations describing the stroke biomechanics. Because the model is used to describe a human/machine system, it is nonlinear. Some thoughts on methods of developing a model of the physiology of racing wheelchair propulsion are also presented.

Biomechanical Phenomena↗
PubMed1990

Wheelchair racing sports science: a review.

Wheelchair racing science and the performance of athletes involved in wheelchair racing have developed rapidly in recent years. With increasing interest in this sport, the need arises to identify areas where further research is necessary and cooperation between individuals with various backgrounds is encouraged. Many of the problems facing investigators in this field require knowledge in several areas of science and engineering, which suggests an interdisciplinary approach to these issues. Further progress would also benefit from the development of more quantitative methods for the classification of wheelchair athletes, or a restructuring of the classification system; development of sophisticated instrumentation for racing wheelchairs; standardization of test procedures and more complete reporting of results of studies; and, more in-depth mathematical modelling and computer simulation of wheelchair racing. This review presents an overview of four areas of wheelchair racing science: 1) classification of wheelchair athletes; 2) design and analysis of racing wheelchairs; 3) biomechanics of racing wheelchair propulsion; and, 4) training and coaching of wheelchair racers.

Biomechanical Phenomena↗