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Biomedical subjects

D Roberts

Publications and source records attributed to D Roberts.

At least 253 records · Page 14Linked to original sources
PubMed1992

Physical, physiological and performance differences between Canadian national team and universiade volleyball players.

Volleyball has been described as an 'interval' sport with both anaerobic and aerobic components. At the higher skill levels, technical performance may be limited by physical characteristics as well as physical fitness, and performance characteristics such as speed and vertical jump. This investigation compared teams at the two uppermost levels of men's volleyball in Canada for differences in physical, physiological and performance characteristics. The subjects were members of the national (n = 15) and universiade teams (n = 24). The parameters examined included percent body fat, maximal oxygen uptake (VO2 max), anaerobic power, bench press, 20-m sprint time and vertical jumping ability. The only significant difference in physical characteristics between the two teams was in age. Despite similarities in standing and reach height, the national team players had significantly higher block (3.27 vs 3.21 m) and spike (3.43 vs 3.39 m) jumps. An evaluation of anaerobic power measures produced similar power outputs during a modified Wingate test, yet the national team members had higher scores (P less than 0.05) for spike and block jump differences as well as 20-m sprint time. The large aerobic component of elite volleyball play was supported by the high VO2 max value recorded for the national team players (56.7 vs 50.3 ml kg-1 min-1). The results suggest that either years of specific physical conditioning and playing or the selection of individuals for the national team who possess more desirable characteristics as a consequence of genetic endowment, plays a significant role in the preparation of international calibre volleyball players.

Anthropometry↗
PubMed1992

Fully three-dimensional reconstruction from data collected on concentric cubes in Fourier space: implementation and a sample application to MRI.

An algorithm is proposed for rapid and accurate reconstruction from data collected in Fourier space at points arranged on a grid of concentric cubes. The Fourier transform of the object to be reconstructed is decomposed into the sum of three functions by subdividing its domain into three non-overlapping mutually orthogonal double pyramids. Each of the three functions is zero-valued outside one of the double pyramids and has values inside that double pyramid which are the same as those of Fourier transform of the object to be reconstructed at the same points. Inverse Fourier transforms of these individual functions can be calculated using the chirp z-transform. The outputs of these inverse transforms for the three functions are estimates of their values at points of the same rectangular grid. The function to be reconstructed is estimated for this grid by adding together the three inverse transforms. The whole process has computational complexity of the same order as required for the 3D fast Fourier transform and so (for medically relevant sizes of the data set) it is faster than backprojection into the same size rectangular grid. The design of the algorithm ensures that no interpolations are needed, in contrast to methods involving backprojection with their unavoidable interpolations. As an application, a 3D data collection method for MRI has been designed which directly samples the Fourier transform of the object to be reconstructed on concentric cubes as needed for the algorithm.

Algorithms↗
PubMed1992

In utero infection due to Pasteurella multocida in the first trimester of pregnancy: case report and review.

To our knowledge, we report the first case of in utero infection in humans due to Pasteurella multocida in the first trimester of pregnancy. After antibiotic therapy was initiated, the mother recovered rapidly from bacteremia but the fetus was spontaneously aborted. Pathological examination of the fetus and placenta revealed acute deciduitis and chorionitis, indicating an infectious etiology for the abortion. The clinical and pathological features of this case are compared with those of the five previously reported cases of P. multocida bacteremia in humans that occurred during pregnancy.

Abortion, Spontaneous↗
PubMed1992

Different vasodilating mechanisms--different peripheral effects?

Many factors, both local and systemic, are known to influence the caliber of peripheral vessels and regional blood flow. Methods of studying limb blood flow and its alteration by disease and drugs present considerable problems. We compared the effects of a series of antihypertensive drugs on limb blood flow and their functional effects in patients with hypertension and peripheral vascular disease. Results from studies with new antihypertensive drugs such as carvedilol are awaited.

Adrenergic beta-Antagonists↗
PubMed1992

Proportional assist ventilation. Results of an initial clinical trial.

The response to proportional assist ventilation (PAV) was tested in four normal subjects during heavy exercise and in five ventilator-dependent patients recovering from assorted medical disorders. The apparatus consisted of a rolling-seal piston coupled to a motor that generated pressure in proportion to inspired flow and inspired volume, with the gains adjusted such that the proportionality between airway pressure (Paw) and instantaneous patient-generated pressure (Pmus) was approximately 1:1 (i.e., machine-amplified patient effort by a factor of 2). Normal subjects responded to PAV by decreasing their own effort, as judged from esophageal pressure, such that the changes in ventilation and breathing pattern were rather small (VE: 64.8 +/- 3.6 during PAV versus 56.0 +/- 4.3, p less than 0.01; VT: 2.39 +/- 0.24 versus 2.02 +/- 0.17, p less than 0.05; f: 27.5 +/- 1.9 versus 28.0 +/- 2.2, NS). In patients, elastance ranged from 20 to 35 cm H2O cm/L, resistance ranged from 5 to 10 cm H2O/L/s, and maximal inspiratory pressure ranged from -16 to -65 cm H2O. After a period of observation during synchronized intermittent mechanical ventilation (SIMV) the patient was switched to PAV and maintained on it for 1 to 3 h. No patient had to be replaced on SIMV because of discomfort or deterioration in any of the monitored variables. During PAV peak airway pressure was less than half the value observed with the IMV breaths (16.6 +/- 2.4 versus 35.4 +/- 3.4 cm H2O, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Cefaclor as a prophylactic agent for recurrent urinary infections: a comparative trial with macrocrystalline nitrofurantoin.

Eighty women with recurrent urinary infections (a median of seven episodes per year) were randomized to twelve months prophylaxis with cefaclor 250 mg or macrocrystalline nitrofurantoin 50 mg, at night. Seventy-three patients (37 given cefaclor and 36 given macrocrystalline nitrofurantoin) were assessable for efficacy. The incidence of radiological abnormalities in the two treatment groups was 23% and 30% respectively. Ninety-five percent of the patients taking cefaclor were symptomatically improved during the twelve months of prophylaxis and 86% remained abacteriuric; corresponding figures in the group taking macrocrystalline nitrofurantoin were 86% and 85% respectively. There were 88 breakthrough infections in patients taking cefaclor (6 resistant strains), and 9 in those patients taking macrocrystalline nitrofurantoin (6 by resistant strains). The mean interval between symptomatic episodes on prophylactic therapy increased by 5.6-fold in patients taking cefaclor, and 4.3-fold in those taking macrocrystalline nitrofurantoin. Resistant coliforms were found in only 3 out of 37 patients studied after twelve months prophylaxis; these organisms did not proceed to cause infections. All 80 patients were assessable for adverse events: 5 out of 39 taking cefaclor (12.8%) reported an event "probably" associated with the antibiotic, and 3 (7.7%) stopped taking the drug for various reasons; corresponding figures for macrocrystalline nitrofurantoin were 17.1% and 9.8% respectively. Patients with a radiological abnormality responded well to long-term low-dose prophylaxis with either agent. Cefaclor seems to offer an alternative to macrocrystalline nitrofurantoin for the prophylaxis of recurrent urinary infections in women.

Adult↗
PubMed1992

Coverage by four information services of the core journals of rehabilitation and related topics.

In this study, three serials databases were used to identify core journals in rehabilitation and related areas. Simple strategies were used to search SERLINE (Serials Online, National Library of Medicine), Ulrich's International Periodicals Directory and SACHET (British Library serials database). Coverage of the journals identified by four secondary information services was then studied. These were Medline, Excerpta Medica, CINAHL (Cumulative Index to Nursing and Allied Health) and CATS (Current Awareness Topics Services, British Library). The results confirmed and extended the findings of earlier work: the number of core journals in rehabilitation is very large and their coverage by information services is very selective. Of the services studied here, CATS seemed to be most comprehensive for the journals identified.

Databases, Factual↗
PubMed1992

Training at moderate altitude: iron status of elite male swimmers.

Laboratory evidence of suboptimal iron status is endemic in chronically training athletes, yet the importance of low serum ferritin values to athletic performance is unclear. The purpose of this study was to monitor iron status in nine male elite swimmers during and after a 3-week training camp at 2225 m altitude. Values for hemoglobin, hematocrit, serum iron, serum transferrin, and transferrin saturation were within the normal range and remained unchanged over the 54-day monitoring period. Serum ferritin level was significantly decreased by day 13 and continued to decline over the period at altitude. Significant recovery was observed by day 35, by which the workload and altitude were reduced. Reticulocyte counts were raised above normal values by the fifth day at altitude and remained elevated for the duration of the study, indicating increased erythropoiesis. In contrast, neither ferritin levels nor reticulocyte counts were changed in six of the nine subjects after 1 month's training at 1000 m. Food histories revealed dietary iron intakes two to three times as great as the recommended dietary allowance for iron. The draw on body iron reserves observed in this study over the heavy training period at moderate altitude indicates that adequate iron stores are necessary to provide a reservoir of iron during periods of increased iron utilization or loss. Further work is required to elucidate the sources and endpoints of the observed iron flux.

Adult↗
PubMed1992

Efficacy of antiperspirants on feet.

Nineteen male soldiers participated in a study of the effectiveness of two antiperspirants (aluminum chlorohydrate and aluminum zirconium tetrachlorohydrex glycine) in reducing foot-sweat accumulation and injuries. Each subject was tested before and after antiperspirant application, with a 1-hour treadmill march at 5.6 km/hour in a warm environment. Both antiperspirants decreased (p less than 0.05) foot-sweat accumulation over 50%. There was also a tendency, although not statistically significant, for subjects to incur fewer blisters with antiperspirant use. However, the antiperspirants also increased (p less than 0.05) the incidence of irritant dermatitis. Nevertheless, these data suggest that the application of antiperspirants to the feet has merit in reducing serious foot injuries (blisters, trench foot) exacerbated by wet feet.

Adult↗
PubMed1991

Control of blood gas measurements in intensive-care units.

The frequency of blood gas measurement in two adult intensive-care units was assessed for 7 months before and 12 months after introduction of a protocol of indications for such investigation. Demographic, diagnostic, outcome, and intervention data were collected prospectively. There were no differences in demographic characteristics, severity or type of illness, survival, or frequency of arterial or pulmonary artery catheter use between the two observation periods, but the frequency of blood gas analysis fell by 44% (p less than 0.001) after the protocol was introduced.

Aged↗
PubMed1991

Excess number of bladder cancers in workers exposed to ortho-toluidine and aniline.

A retrospective cohort study of the incidence of bladder cancer was conducted in response to a union request for an evaluation of a possible excess number of cases of bladder cancer at a chemical plant in western New York State. Workers at the plant were exposed to two potential bladder carcinogens--ortho-toluidine (o-toluidine) and aniline. Incidence rates of bladder cancer among workers at the plant were compared with those of the population of New York State (excluding New York City). Among all 1749 workers at the plant, 13 cases of bladder cancer were observed versus 3.61 expected [standardized incidence ratio (SIR) = 3.60; 90% confidence interval (CI) = 2.13-5.73]. Among the 708 workers who worked in areas in which o-toluidine and aniline were used, 7 cases were observed versus 1.08 expected (SIR = 6.48; 90% CI = 3.04-12.2). Among the 288 maintenance, shipping, and janitorial workers thought to have been possibly exposed, 4 cases were observed versus 1.09 expected (SIR = 3.66; 90% CI = 1.25-8.37). Among the remaining 753 workers who were probably not exposed, 2 bladder cancers were observed versus 1.43 expected (SIR = 1.39; 90% CI = 0.25-4.39). Increased risk of bladder cancer was strongly associated with increased duration of employment in the department where o-toluidine and aniline were used (P less than .001). Among workers with 10 or more years of employment in the department, the SIR was 27.2 (90% CI = 11.8-53.7). o-Toluidine is an animal carcinogen more potent than aniline and is known to produce bladder tumors in rats; hence, it is more likely that o-toluidine is responsible for the observed excess number of cases of bladder cancer, although aniline may have played a role.

Adult↗
PubMed1991

The epidemiology of dementia in North America.

In this brief review, the epidemiology of dementia in North America is examined. The areas covered are prevalence and incidence studies, longitudinal studies, risk factors, distribution of types of dementia, cross-cultural factors and current research programmes.

Aged↗
PubMed1991

The occurrence of Listeria species in milk and dairy products: a national survey in England and Wales.

A total of 4172 samples of milk, cheese and other dairy products were examined over a 1-year period for the presence of Listeria species. Strains of Listeria were found most frequently in soft, ripened cows milk cheese; 63 out of 769 (8.2%) samples contained Listeria monocytogenes, 25 samples contained species other than L. monocytogenes, and 18 samples contained both L. monocytogenes and other Listeria spp. Eleven samples of pasteurized cows milk (1.1%) from four dairies contained L. monocytogenes, and other Listeria spp. were isolated from a further five samples. Goats and ewes milk and their products, yogurt, cream and ice cream also occasionally contained Listeria spp. Levels of Listeria were usually low, but 20 samples of cheese contained more than 1000 cfu/g. Most strains of L. monocytogenes belonged to serotype 1/2 (58%) or serotype 4b (33%).

Animals↗
PubMed1991

The influence of age on the durability of Carpentier-Edwards biological valves. Thirteen years follow-up.

Two hundred and ninety-nine patients received 325 Carpentier-Edwards biological valves from April 1976 to April 1982. Valves were placed in the following positions: 150 aortic (AVR), 120 mitral (MVR), 26 multiple (MR), 2 pulmonary (PR) and 1 tricuspid (TR). The mean age was 54.7 years. The total follow-up time was 2545 patient-years. Patients were divided into different age groups: less than 40, 40-49, 50-59, 60-69 and greater than 70 years and were followed-up for reoperations and tissue failure. Ninety-three operations were performed in 91 patients (30.5%) for valve related dysfunctions. The main cause of reoperation was primary tissue failure (85%). The respective incidence and risk of reoperation in the different age groups were 51.5% and 5%, 41.5% and 4%, 32% and 3%, 18% and 2.5%, and 0% for greater than 70 years of age. The risk of reoperation decreased significantly with increasing age (P less than 0.05). The respective incidence and risk of tissue failure in the age groups were 43.8% and 4.1%, 35% and 4%, 27.3% and 3.2%, and 17.2%, 2.4% and 0%. The freedom from reoperation and tissue failure was significantly higher in the older patient (greater than 60 years) compared to the younger patients (less than 60 years). The commonest cause of failure in young patients was calcification, while in older patients it was cusp rupture. Comparing aortic and mitral bioprostheses in the different age groups showed no difference between these valves in patients less than 50 years of age.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Body composition in myelomeningocele.

Body composition and measures of obesity were evaluated in 59 subjects with myelomeningocele (MMC), aged 0.3-29 y, by anthropometry and measures of body cell mass (BCM) and intra- and extracellular water (ICW and ECW), derived from total body potassium and deuterium-isotope dilution; these results were compared with reference data. Body composition was normal in preambulatory children with MMC. Beyond ages 3-4 y there was significant depletion of BCM and total body water, with maldistribution of water (increased ECW and decreased ICW) and increased percentage body fat above that expected for age and sex. These findings were more pronounced in females and in those with high lesions, and were less pronounced in those who remained ambulatory. These changes may result in metabolic and nutritional maladaption during stress. The relation of BCM, total body water depletion and increased ECW to decreasing ambulatory activity suggests that early nutritional and mobility programs warrant further study.

Adipose Tissue↗