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R J Brooks

Publications and source records attributed to R J Brooks.

At least 19 recordsLinked to original sources
PubMed2002

An investigation of the repeatability and reproducibility of ISO 11948-1 (the Rothwell method) for measuring the absorption capacity of incontinence pads.

The repeatability and reproducibility (precision within and between laboratories, respectively) of an international standard method (ISO 11948-1, the Rothwell method) for measuring the absorption capacity of incontinence pads was investigated. The 74 shaped disposable bodyworn insert pads for heavy incontinence on the UK market in spring 1997 were tested in three laboratories experienced in using the method, one in each of England, Spain and Sweden. Coefficients of variation (standard deviation as a proportion of the mean) for five repeats rarely exceeded 5% within any laboratory. However, there were systematic differences between laboratories: results from the Swedish and Spanish laboratories typically exceeded those from the English laboratory by 13% and 8%, respectively. The good repeatability suggests that the method is capable of adequate precision but the poor reproducibility implies that the instructions in the standard for building and/or using the test apparatus are inadequate, leaving too much room for interpretation. Having studied the data presented here and viewed videos of the apparatus in use in five laboratories (including the three contributing to this note) the ISO working group which wrote the original standard has identified several likely sources of imprecision and is now working to revise the standard to improve its reproducibility.

England↗
PubMed1999

Effect of dichlorodiphenyltrichloroethane on sex determination of the common snapping turtle (Chelydra serpentina serpentina).

Recent evidence indicates that 1,1,1-trichloro-2, 2-bis(p-chlorophenyl)ethane (DDT) and some of its metabolites alter reproductive and endocrine function in wildlife. Exposure to such endocrine-disrupting compounds during embryonic development can affect sexual differentiation. The authors tested the hypothesis that dichlorodiphenyltrichloroethane (p,p'-DDE) causes feminization of the common snapping turtle (Chelydra s. serpentina), a species with temperature-dependent sex determination, during embryonic development. Eggs from eight clutches (total eggs tested=237) were incubated at a male-producing temperature (26 degrees C). At stage 14 of embryonic development, p,p'-DDE was applied topically at four concentrations and estrogen (estradiol-17 beta) was applied as a positive control. Although application of estrogen did induce female development at this temperature, application of p,p'-DDE did not affect sex determination at the exposure levels used. Residue analysis indicated that the amount of p,p'-DDE detected in the eggs 72 h after application was considerably less than the concentrations applied. However, the amounts that penetrated the shells were comparable to levels which have been found in moderately contaminated sites in the Great Lakes. These results indicate that p, p'-DDE, at levels that exist in the environment in the Great Lakes, does not cause the feminization of snapping turtles during embryonic development.

Animals↗
PubMed1998

Disposable bedpads for incontinence: predicting their clinical leakage properties using laboratory tests.

A multi-centre project has been run to identify laboratory tests capable of predicting the leakage performance of disposable incontinence bedpads. Each of 95 subjects tested each of six products for a week in turn and reported whether or not they and/or their carers found the leakage performance of each product acceptable. In addition, carers noted the severity with which individual used bedpads had leaked so that, when they had been weighed, their leakage performance could be determined as a function of urine weight. These clinical data were compared with results from the 16 different laboratory tests used routinely for bedpad evaluation in three hospital laboratories. Each test was evaluated by seeing how well the data it yielded correlated with the clinical test data. No individual test was very successful at predicting the performance of bedpads when used as sole protection but a combination of an absorption capacity test and an absorption time test predicted the percentage of users/carers finding leakage performance acceptable, accurate to within +/- eight percentage points for all six test products. A different absorption capacity test proved most successful for bedpads used as back-up to body-worn products. It predicted the percentage of users/carers finding leakage performance acceptable, accurate to +/- five percentage points for all six products.

Absorption↗
PubMed1998

Impact of organochlorine contamination on levels of sex hormones and external morphology of common snapping turtles (Chelydra serpentina serpentina) in Ontario, Canada.

Recent research has suggested that contaminants in the environment may influence sex differentiation and reproductive endocrine function in wildlife. Concentrations of organochlorine contaminants (total polychlorinated biphenyls, pesticides) were higher in the blood plasma of snapping turtles from contaminated sites than in those from reference sites. The ratio of the precloacal length to the posterior lobe of the plastron (PPR) is sexually dimorphic in snapping turtles. There were significant reductions in the PPR at three contaminated sites versus two reference sites. The magnitude of the response was such that a significantly higher proportion of PPRs of males from a contaminated site (Cootes Paradise) overlapped with those of females than PPRs of males from a reference site (Lake Sasajewun). Observers can incorrectly identify the sex of turtles at the contaminated site based on secondary sexual characteristics alone. Unlike the changes to the morphology, there were few changes in 17 beta-estradiol or testosterone levels, and where differences occurred, there was more variation among reference sites than between the reference and contaminated sites. Our results suggest that environmental contaminants may affect sexually dimorphic morphology in snapping turtles without affecting circulating testosterone or estrogen levels in the adults.

Animals↗
PubMed1997

Predicting the leakage performance of small bodyworn disposable incontinence pads using laboratory tests.

An international multi-centre project has been run to create an international standard for measuring the leakage performance of small, disposable incontinence pads for lightly incontinent women. One hundred and thirteen women tested batches of nine different incontinence pads of widely differing designs and noted the severity with which each individual used pad had leaked so that leakage performance could be determined as a function of urine weight. In addition, testers rated the overall leakage performance of each of the nine products on a five-point scale. These clinical data were compared with laboratory data from 153 different pad measurements, each of which was evaluated by seeing how well the data it yielded correlated with the clinical test data. A wetback test emerged as the clear winner. It usually predicted the clinical leakage performance of pads to an accuracy of +/- 10%. It involved applying 25 ml of 1% w/v saline to a pad and measuring how much escaped into a filter paper held against the wet pad for 1 min under a pressure of 1.5 kPa. Pads which released the least test fluid into the filter paper leaked least in the user tests. The method will be published as an ISO standard during 1997.

Absorption↗
PubMed1996

Cost of breast cancer treatment. A 4-year longitudinal study.

OBJECTIVE: To determine the longitudinal cost of the treatment of patients with breast cancer. METHODS: An analysis was performed of 200 women with 205 newly diagnosed breast cancers during 1989 in a health maintenance organization population (US Healthcare, Blue Bell, Pa). Medical records and claims data were analyzed for the total costs of medical care during the 4-year period after diagnosis. The costs over time were analyzed for clinical stage and use of mammography screening. RESULTS: The total costs of medical care during the 4-year period after diagnosis were strongly related to clinical stage at diagnosis, with higher total costs for patients with stages III to IV at diagnosis compared with patients with stages 0 to II at diagnosis. The cost for all stages of disease declined after years 1 to 2, with the exception of stage II, which increased slightly in years 3 to 4. The use of screening mammography was associated with a significant decrease in the cost of medical care during the 4-year study period. CONCLUSIONS: The goal of mammography screening programs should be to achieve downstaging to stages 0 to 1 to achieve reduction in breast cancer mortality and to reduce the overall consumption of health care resources for the treatment of breast cancer. These cost data should be considered within the framework of future cost-effective analysis for screening mammography programs.

Adult↗
PubMed1996

Temporal and geographic variation of organochlorine residues in eggs of the common snapping turtle (Chelydra serpentina serpentina) (1981-1991) and comparisons to trends in the herring gull (Larus argentatus) in the Great Lakes basin in Ontario, Canada.

Common snapping turtle (Chelydra serpentina serpentina) eggs from five sites within the Great Lakes basin, and from a reference site in north-central Ontario were collected during 1981-1991 and analyzed for four organochlorine pesticides, polychlorinated biphenyls (PCBs) including six non-ortho PCBs, polychlorinated dibenzodioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs). The pattern of geographic variation was consistent over time in eggs with Cootes Paradise/ Hamilton Harbour and Lynde Creek eggs on Lake Ontario containing the highest concentrations and most PCDD and PCDF congeners among all sites. Eggs from Cranberry Marsh on Lake Ontario contained organochlorine concentrations similar to those from Big Creek Marsh and Rondeau Provincial Park on Lake Erie except PCDDs and PCDFs which occurred at higher concentrations and more congeners were detectable in Cranberry Marsh eggs. Concentrations of most contaminants in turtle eggs from Algonquin Park, the reference site, have significantly decreased in the past decade. Dieldrin concentrations, however, increased in Algonquin Park eggs from 1981 to 1989. Significant decreases in concentrations of hexachlorobenzene, mirex and PCBs occurred between turtle eggs collected in 1981/84 and 1989 at Big Creek Marsh and Rondeau Provincial Park, whereas there was no significant change in concentrations of p,p'-DDE and dieldrin. In Lake Ontario eggs, concentrations of PCBs, p,p'-DDE and dieldrin increased significantly between 1984 and 1991. Differences were also found in patterns of temporal variation in contamination between herring gulls (Larus argentatus) and snapping turtles which were attributed to differences in diet. Elevated and continued contamination in turtle eggs from Lake. Ontario is probably due to a combination of local sources of chemicals and consumption of large migratory fish that spawn in wetlands inhabited by these turtles.

Animals↗
PubMed1996

Practice management, health maintenance, and the use of computers in today's medical office.

It is clear that a successful medical practice needs a competent caring physician as well as office personnel who understand how to manage an office. The successful management of a practice helps achieve the goals that the physician and practice manager have established. This article has introduced ideas about how to manage and evaluate a practice. Adoption of some or all of these ideas helps provide more comprehensive and satisfying care for the physician and his or her patients.

Management Information Systems↗
PubMed1995

Increased ERCP rate following the introduction of laparoscopic cholecystectomy.

Over the past 5 years there has been a remarkable change in the manner in which symptomatic gallstones are surgically managed. In this study we reviewed the experience of a large HMO to determine the relationship between the rate of increase of ERCP and that of cholecystectomy. All individuals enrolled in US Healthcare's HMO-PA, in the region of southeastern Pennsylvania from 1988 through 1993, were included in the analysis. Using the HMO claims database, patients who underwent an open or laparoscopic cholecystectomy during the study period were identified. We then identified those patients who had a pre- or post- operative ERCP. Over the study period, there has been a substantial increase in cholecystectomies per 1000 members-from 1.37 in 1988 to 2.16 (p < 0.0001) in 1993. In our study population there were 1261 ERCPs performed in 979 patients with an average of 1.3 ERCPs per patient during the study period. The ERCP rate per 1000 members has increased from 0.16 to 0.56 (p < 0.0001) from 1988 to 1993, at the same time that the cholecystectomy rate was substantially increasing. The correlation for the ERCP and cholecystectomy rates from 1988 to 1993 was 0.994 (p < 0.0001). Since the introduction of laparoscopic cholecystectomy in 1989-1990, many more ERCPs are now being performed. It is necessary to determine the implications related to the rapid diffusion of laparoscopic cholecystectomy, including the effect that this technology has had on other older and stable technologies such as ERCP. Our results describe the dramatic effect that laparoscopic cholecystectomy has had on the utilization of ERCPs.

Cholangiopancreatography, Endoscopic Retrograde↗
PubMed1991

The case for a cause-effect linkage between environmental contamination and development in eggs of the common snapping turtle (Chelydra S.serpentina) from Ontario, Canada.

Concentrations of polychlorinated biphenyls (PCBs), dibenzo-p-dioxins, and dibenzofurans, organochlorine pesticides, and their metabolites were measured in eggs of the common snapping turtle (Chelydra s.serpentina) collected from four wetlands on the shorelines of Lakes Ontario, and Erie, and one control location in central Ontario, Canada. Snapping turtle eggs from these sites were also artificially incubated to determine hatching success, and incidence of deformities in embryo and hatchling turtles. The hypothesis that elevated incidences of egg death and/or deformities of hatchling turtles would occur in populations with high concentrations of organochlorine contaminants in eggs was tested. The results were elevated using epidemiological criteria. Unhatched eggs and deformities occurred at significantly higher rates in eggs from Lake Ontario wetlands. Two of three sites from Lake Ontario had substantially higher levels of PCBs, dioxins, and furans compared to eggs from Lake Erie and the control site. It could not be shown that contamination of eggs preceded the occurrence of poor development of eggs, although excellent hatching success and low numbers of deformities in eggs from the control site were considered representative of development in healthy eggs. The statistical association between contaminant levels in eggs and poor development of these eggs supported the hypothesis that eggs from sites with the greatest contamination had the highest rates of abnormalities. PCBs were the most strongly associated chemicals, although possible effects due to the presence of other chemicals in eggs was a confounding factor. The deformities and rates of unhatched eggs were similar to those occurring in other vertebrates collected from highly contaminated areas of the Great Lakes. There were several chemicals present in the eggs that can cause similar reproductive effects in other species; therefore a specific chemical effect was not identified. Results were coherent with known statistical and biological information. Theoretical and factual evidence of PCB contamination in wild-caught snapping turtles supported and hypothesis. However, lack of controlled studies of reproductive effects of polychlorinated hydrocarbons upon this species hindered the agreement of all factual and theoretical evidence with the hypothesis.

Animals↗
PubMed1991

Modelling sub-binomial variation in the frequency of sex combinations in litters of pigs.

In some samples of pig litters, the number of males per litter exhibits significant sub-binomial dispersion: there are fewer unisexual and more "sex-balanced" litters than expected under a binomial model. It is argued here that the explanation is that the sex of zygotes may be subject to hormonal control with the consequence that, within a litter, the zygotes do not all have the same probability of being male. This variation in probability is approximated by a quadratic function of the time during oestrus that a zygote is formed so as to parallel the variation in maternal hormone levels. Other explanations are examined briefly, but each seems to have serious weaknesses.

Analysis of Variance↗
PubMed1989

Ultrastructural development of the sarcocyst of Sarcocystis rauschorum (Apicomplexa: Sarcocystidae) in the varying lemming Dicrostonyx richardsoni.

The development of the sarcocyst of Sarcocystis rauschorum in its intermediate host was studied. Lemmings were orally administered sporocysts of S. rauschorum obtained from snowy owls (Nyctea scandiaca). Beginning at 9 days postinoculation (DPI) and at various intervals to 84 DPI, skeletal muscle tissue taken from the infected lemmings was examined by electron microscopy. At 9 DPI the sarcocysts contained few metrocytes and the cyst wall was flat. The metrocytes underwent endodyogeny, and within a few days the cyst wall of the rapidly growing sarcocyst developed numerous tubulovesicular invaginations into the electron-dense layer, and the wall had a few irregular infoldings. By 21 DPI, banana-shaped bradyzoites appeared, and by 84 DPI the mature cysts were filled with bradyzoites in groups subdivided by septa and by deep infoldings of the cyst wall. The fine structure of the wall remained simple throughout maturation, with no conspicuous invagination or protrusion. The sarcocyst produced in response to S. rauschorum is unlike those from many species of Sarcocystis, which have complex walls that change markedly as the sarcocysts mature; however, its simple appearance is similar to other species that have rodents as intermediate hosts and raptorial birds as definitive hosts.

Animals↗
PubMed1988

Hatchling turtles survive freezing during winter hibernation.

Hatchlings of the painted turtle (Chrysemys picta marginata) are unique as the only reptile and highest vertebrate life form known to tolerate the natural freezing of extracellular body fluids during winter hibernation. Turtles survived frequent exposures to temperatures as low as -6 degrees C to -8 degrees C in their shallow terrestrial nests over the 1987-1988 winter. Hatchlings collected in April 1988 had a mean supercooling point of -3.28 +/- 0.24 degrees C and survived 24 hr of freezing at -4 degrees C with 53.4% +/- 1.98% of total body water as ice. Recovery appeared complete after 20 hr of thawing at 3 degrees C. However, freezing at -10.9 degrees C, resulting in 67% ice, was lethal. A survey of possible cryoprotectants revealed a 2- to 3-fold increase in glucose content of liver and blood and a 3-fold increase in blood glycerol in response to freezing. Although quantitatively low, these responses by spring turtles strongly indicate that these may be the winter-active cryoprotectants. The total amino acid pool of blood also increased 2.25-fold in freezing-exposed turtles, and taurine accounted for 52% of the increase. Most organs accumulated high concentrations of lactate during freezing, a response to the ischemic state imposed by extracellular freezing. Changes in glycogen phosphorylase activity and levels of glucose 6-phosphate and fructose 2,6-bisphosphate were also consistent with a dependence on anaerobic glycolysis during freezing. Studies of the molecular mechanisms of natural freeze tolerance in these turtles may identify protective strategies that can be used in mammalian organ cryopreservation technology.

Animals↗
PubMed1988

Neurobehavioral and psychosocial functioning of women exposed to high altitude in mountaineering.

The effects of chronic hypoxemia upon cognition and behavior were studied in women exposed to high altitude in mountaineering. Neuropsychological tests and psychosocial and physiological questionnaires were given to eight women before, during, and immediately after a Himalayan climb to 20,500 feet. Cognitive functioning remained relatively intact with only two significant decrements, complex abstract reasoning and word-finding ability. Significant changes were found on all psychosocial and physiological questionnaires. Feelings of acceptance of others and anxiety declined significantly. Physical symptoms were greatest during the first five days of ascent. Subjects' self-ratings of mental functioning were significantly better after the expedition than either before or during the climb. Self-assessments were correlated with emotions and physical symptoms, not with actual performances on the test battery. It is suggested that complex cognitive tasks and psychosocial functioning be studied in more detail as these were more influenced by exposure to high altitude in mountaineering.

Adult↗
PubMed1987

Cholesterol hydroperoxides inhibit calmodulin and suppress atherogenesis in rabbits.

A mixture of cholesterol autoxidation products, prepared from an aged sample of cholesterol by recrystallization from methanol, inhibits calmodulin irreversibly in a Ca2+-dependent reaction. Inhibitory activity is lost after treatment with NaBH4, NaCNBH3, or NaI, from which we conclude that calmodulin inhibition is due to one or more cholesterol hydroperoxides. Partially purified cholesterol hydroperoxides, with or without cholesterol, were fed to young adult white rabbits. Cholesterol in the diet caused extensive atheroma formation in the aortas, but the addition of cholesterol hydroperoxides markedly reduced lesion formation. A cholesterol hydroperoxide preparation that was reduced by treatment with NaI was not effective in preventing atheroma formation. Cholesterol hydroperoxides did not lower cholesterol concentrations in blood plasma, liver, or heart.

Aging↗
PubMed1987

Pathogenesis of infection with Sarcocystis rauschorum (Apicomplexa) in experimentally infected varying lemmings (Dicrostonyx richardsoni).

This study describes the sequential formation of lesions associated with the endogenous development of Sarcocystis rauschorum (Apicomplexa: Sarcocystidae) in varying lemmings, Dicrostonyx richardsoni. Lethal doses of sporocysts (greater than 500) were orally administered to lemmings examined 1-6 days postinoculation (DPI) whereas sublethal doses were administered to lemmings examined subsequently. Transient necrosis and purulent inflammation, in association with precystic merogony, occurred in the liver by 4.5 DPI, peaked at 6 DPI and subsided beginning at 11 DPI with the liver returning to normal by 15 DPI. Cyst formation in skeletal and cardiac muscle was associated with purulent inflammation and sarcolemmal proliferation beginning at 9 DPI. These lesions persisted to 42 DPI. In addition, multifocal nonsuppurative meningoencephalitis was present in six of 11 infected lemmings examined between 11 and 15 DPI.

Animals↗
PubMed1987

Effects of the protozoan parasite Sarcocystis rauschorum on open-field behaviour of its intermediate vertebrate host, Dicrostonyx richardsoni.

Behaviour and activity levels were measured in varying lemmings experimentally infected with the heteroxenous parasite, Sarcocystis rauschorum to test the hypothesis that the parasite alters behaviour of this intermediate host and thereby increases probability of transmission to the definitive host, the snowy owl (Nyctea scandiaca). Measures of short-term activity levels on a running wheel indicated no effect of the parasite, either directly, or indirectly as a result of illness. We observed behaviour of infected lemmings placed in an "open field" (arena). Lemmings would increase their susceptibility to predators if they spent more time away from cover, used crypsis (stationary postures) less, spent more time exploring (especially in unfamiliar areas), or responded inappropriately to threats from predators. We found that only exploratory activity showed significant change after infection. The frequency of exploratory activity increased and became disassociated from the usual fear response. This may increase the lemmings' susceptibility to aerial predation. The mechanism for this effect is unknown, but neurological lesions have been observed. The examination of the modes of transmission of the S. rauschorum parasite within lemming populations and of a possible fecundity compensation strategy adopted by the lemmings, and their relevance to population control, are suggested as areas for future study.

Animals↗