Search PubMed⌕ Search

Biomedical subjects

P Cooper

Publications and source records attributed to P Cooper.

At least 37 records · Page 2Linked to original sources
PubMed2001

The safest surgical incisions and amputations applying the angiosome principles and using the Doppler to assess the arterial-arterial connections of the foot and ankle.

Knowing the arterial anatomy of the foot and ankle in addition to understanding the angiosome concept provides the basis for careful and safe planning of incisions. The Doppler allows the surgeon to map out the actual vascular anatomy that exists preoperatively and therefore allows for appropriate adjustment to the planned incisions. If the vascular flow is inadequate for the planned surgery, then the vascular surgeon has to intervene to improve the existing blood flow. If the vascular tree is so compromised that successful revascularization of the affected angiosome is impossible, then the revascularization is likely to fail. Serious consideration to a below-knee amputation should then enter the decision tree at that time. Most of the time, however, the blood flow is adequate or can be sufficiently augmented with vascular surgery. The foot and ankle surgeon can then perform preoperative mapping of the arterial blood supply with the Doppler. By making the necessary adjustments to the planned incision, surgery can proceed safely with uneventful healing.

Amputation, Surgical↗
PubMed2001

Optimizing the indexing of a resolution-enhancing tertiary collimator for radiotherapy.

A method for improving the resolution of multileaf collimator (MLC) defined radiotherapy fields using a tertiary, slotted grid collimator has been investigated and developed further. The original concept was for each slot to be aligned with each leaf pair of opposing MLC leaves. The total treated area is composed of a series of sub-fields, a pattern of irradiated strips, with the width of each strip defined by the width of the slot and the length by the relative separation of the MLC leaf pair. To complete the field, the patient must be indexed relative to the collimator, with the number of sub-fields required determined by the width of the slots and the spacing between them. Two methods were considered by which this indexing could be achieved: movement of the patient while holding the tertiary collimator fixed, or rotating the grid with the point of rotation defined as the radiation source. Consideration of the movement resolution and precision required for the patient support system for non-cardinal gantry, collimator and table angles cast doubt on the practicality of the use of such a strategy. To assess the effect of divergence on the abutting sub-fields, measurements were also performed to assess the uniformity of single fields generated by the tertiary collimator in planes above and below the isocentre using both methods of indexing. As expected, rotation of the collimator resulted in a similar degree of non-uniformity for any plane chosen, whereas significant dose heterogeneities were introduced to treatment planes within 5 cm above and below the isocentre if the patient support system was used. Therefore, the rotation strategy will be implemented with all future versions of the device.

Humans↗
PubMed2001

The measurement of kappach factors for application with the IPEMB very low energy dosimetry protocol.

In 1996. the IPEMB issued a new code of practice detailing the procedures by which the output of therapeutic kilovoltage x-ray devices are to be determined. For x-ray beam qualities in the range 0.035-1.0 mm Al half-value thickness (HVL), the equation for converting the instrument reading into absorbed dose to water contained a factor named kch. This was included to account for the change in response of the parallel plate chamber from its calibration conditions free in air to those in the user's measurement phantom. As no data were available with which to quantify this factor at very low energies, the code advised that the user take a value of unity until sufficient data became available upon which to base an addendum. In this work, kch values have been determined for four chambers: two PTW 23344 large volume soft x-ray chambers, one PTW 23342 small volume soft x-ray chamber and a Markus electron chamber. Variations in the value of kch were investigated for changes in FSD, applicator size and beam quality. The water equivalence of the Mix-D phantom used for these measurements was also verified. A comparison of the results for the two PTW 23344 chambers showed no significant differences for any experimental situation, indicating that kch is a factor of chamber design rather than variations in construction. No variation in kch was identified with changes in FSD. A small dependence on applicator size was identified for larger applicators, and this was found to be dependent upon chamber design. The measured values of kch were found to increase with energy and again differences were seen between chamber designs. Overall, the values of kch recorded during these measurements ranged from 1.01 to 1.08. These results highlight a significant underestimation of doses calculated using the very low energy code of practice. This supports the need for further work to confirm these results. and the production of an addendum to the code in its present form.

Calibration↗
PubMed2001

Lenercept (p55 tumor necrosis factor receptor fusion protein) in severe sepsis and early septic shock: a randomized, double-blind, placebo-controlled, multicenter phase III trial with 1,342 patients.

OBJECTIVE: Phase III study to confirm a trend observed in a previous phase II study showing that a single dose of lenercept, human recombinant p55 tumor necrosis factor receptor-immunoglobulin G1 (TNFR55-IgG1) fusion protein, decreased mortality in patients with severe sepsis or early septic shock. DESIGN: Multicenter, double-blind, phase III, placebo-controlled, randomized study. SETTING: A total of 108 community and university-affiliated hospitals in the United States (60), Canada (6) and Europe (42). PATIENTS: A total of 1,342 patients were recruited who fulfilled the entry criteria within the 12-hr period preceding the study drug administration. INTERVENTION: After randomization, an intravenous dose of 0.125 mg/kg lenercept or placebo was given. The patient was monitored for up to 28 days, during which standard diagnostic, supportive, and therapeutic care was provided. MEASUREMENTS AND MAIN RESULTS: The primary outcome measure was 28-day all-cause mortality. Baseline characteristics were as follows: a total of 1,342 patients were randomized; 662 received lenercept and 680 received placebo. The mean age was 60.5 yrs (range, 17-96 yrs); 39% were female; 65% had medical admissions, 8% had scheduled surgical admissions, and 27% had unscheduled surgical admissions; 73% had severe sepsis without shock, and 27% had severe sepsis with early septic shock. Lenercept and placebo groups were similar at baseline with respect to demographic characteristics, simplified acute physiology score II-predicted mortality, profiles of clinical site of infection and microbiological documentation, number of dysfunctioning organs, and interleukin-6 (IL-6) plasma concentration. Lenercept pharmacokinetics were similar in severe sepsis and early septic shock patients. Tumor necrosis factor was bound in a stable manner to lenercept as reflected by the accumulation of total serum tumor necrosis factor alpha concentrations. There were 369 deaths, 177 on lenercept (27% mortality) and 192 on placebo (28% mortality). A one-sided Cochran-Armitage test, stratified by geographic region and baseline, predicted 28-day all-cause mortality (simplified acute physiology score II), gave a p value of .141 (one-sided). Lenercept treatment had no effect on incidence or resolution of organ dysfunctions. There was no evidence that lenercept was detrimental in the overall population. CONCLUSION: Lenercept had no significant effect on mortality in the study population.

APACHE↗
PubMed2001

Cognitive vulnerability to depression in 5-year-old children of depressed mothers.

Studies of cognitive vulnerability to depression in young children have, in the main, relied on self-report questionnaires (e.g. of self-esteem, attributional style). They have failed to produce convincing evidence of a cognitive vulnerability to depression in children under 8 years. In the current study latent depressive cognitions were investigated in the 5-year-old children (N = 94) of depressed and well mothers in a situation of mild stress, that is, the threat of losing a card deal in a modified version of the competitive children's card game "Snap"'. In the context of "losing", but not "winning", deals, children who had been exposed to maternal depression, either in the previous 12 months or at any other time during their lifetime, were more likely than nonexposed children to express depressive cognitions (hopelessness, pessimism, and low self-worth). The association between depressive cognitions and recent exposure to maternal depression was in part accounted for by current maternal hostility to the child. The results of this study stand in contrast to those of studies which have used questionnaire methods to assess vulnerability to depressive cognitions in this age group. They suggest that it might be important to employ ecologically realistic situations to access latent self-cognitions in young children; and they underscore the importance. increasingly evident in research with adults and older children, of employing methods that involve the induction of low mood in order to elicit cognitions relevant to depression.

Adaptation, Psychological↗
PubMed2001

Comparison of two methods for serotyping Campylobacter spp.

Two serotyping schemes (Penner and Laboratory of Enteric Pathogens [LEP]) based on soluble heat-stable antigens were used to analyze 3,788 Campylobacter sp. isolates. A significant percentage (36.6%) was untypeable using LEP serotyping; greater cross-reaction was also observed. The relative discrimination capabilities of the techniques were similar. Penner serotyping fulfils more of the requisite criteria for typing methods.

Antigens, Bacterial↗
PubMed2001

Identification of genes induced by inflammatory cytokines in airway epithelium.

Epithelial cells lining the airways are thought to play a prominent role in respiratory diseases. We utilized cDNA representational difference analysis to identify the genes in which expression is induced by the proinflammatory cytokines tumor necrosis factor-alpha and interleukin-1beta in primary human bronchial epithelial cells and hence are relevant to airway inflammation. Hybridization of the subtraction product to arrayed cDNAs indicated that known tumor necrosis factor-alpha- and interleukin-1beta-inducible genes such as B94, Zfp36, and regulated on activation normal T cell expressed and secreted were represented, confirming the success of the subtraction experiment. A 1,152-clone library potentially representing genes with higher transcript levels in cytokine-treated human bronchial epithelial cells was generated and sequenced. Sequence similarity searches indicated that these clones represented 57 genes of known function, 1 gene of unknown function, 6 expressed sequence tags, and 2 novel sequences. The expression of 19 of these clones was studied by a combination of Northern blotting and RT-PCR analyses and confirmation of differential expression for 10 known genes, 2 expressed sequence tags, and a novel sequence not represented in any of the public databases was obtained. Thus cDNA representational difference analysis was utilized to isolate known and novel differentially expressed genes, which putatively play a role in airway inflammation.

Blotting, Northern↗
PubMed2001

Influence of psychiatric disorder on the controlling behaviour of mothers with 1-year-old infants. A study of women with maternal eating disorder, postnatal depression and a healthy comparison group.

BACKGROUND: Certain styles of parental controlling behaviour influence child development. Work with mothers with eating disorders suggests that they may be particularly controlling of their infants. AIMS: To examine the nature and specificity of maternal controlling behaviour in mothers with eating disorders compared with mothers who had experienced postnatal depression and a healthy comparison group. METHOD: Mothers with eating disorders (n=34), postnatal depression (n=39) and a healthy comparison group (n=61) and their 12-month-old infants were observed during play and mealtimes, and blind ratings made of verbal and non-verbal control exerted by the mother. RESULTS: Mothers in the eating disorder group used more verbal control, especially strong control. There were no differences between the groups on gentle verbal control and physical contact. Maternal dietary restraint was the one feature of eating disorder psychopathology associated with the use of verbal control. Marital criticism was also associated with the extent of verbal controlling behaviour. CONCLUSIONS: Aspects of maternal control of infants were found to be specific to maternal eating disorder psychopathology.

Analysis of Variance↗
PubMed2001

Comparison of two skin care regimes for incontinence.

It is estimated that 30% of nursing home residents may be faecally incontinent, with those figures rising to 60% for patients in long-stay hospitals (Royal College of Physicians, 1995). Maintaining skin integrity for these patients can be complex. With little clinical information to support carers, choosing a skin care regime that maintains skin integrity for this high-risk group can be difficult. This study aims to compare two recognized skin care regimes, used in the cleansing of patients' skin following an episode of incontinence, and their impact on patients' skin integrity. A total of 93 patients were recruited to the trial from five care of the elderly or dependent service providers. The subjects were randomly allocated to either group A (soap and water; n = 49), or group B (Clinisan (Vernacare); n = 44). Initially, 33 patients in both groups started with healthy skin. However, the results of the final assessment identified only 17 subjects in group A remaining healthy, compared with 27 in group B.

Aged↗
PubMed2001

Nutrition and wound healing: what is the link?

Given the important role played by nutrients in wound healing, all patients with wounds should receive a nutritional assessment. Action must then be taken to address any deficiency.

Anthropometry↗
PubMed2001

Recruitment of research participants from U.S. jury pools.

Psychological research is often criticized for routine use of a narrow and unrepresentative study population-college students. This study investigated the feasibility of recruiting research participants from U.S. jury pools, which by law must include a representative cross-section of the public. A questionnaire was mailed to the jury administrators in the 217 U.S. state court jurisdictions with populations of 250,000 or more. Court officials representing 79 jurisdictions in 30 states and the District of Columbia returned surveys (36% response rate). In addition, respondents who indicated in the mail survey that their court had previously allowed outside investigators to recruit jurors also completed a follow-up telephone interview. While the majority of jurisdictions (61%) opposed participation of jurors in research, 31 jurisdic tions (39%) did not object to this practice. Only 8 of the nonopposed jurisdictions had been asked to host research, and 7 had agreed to do so. The jurisdictions that opened their jury pools to researchers employed a number of strategies to circumvent potential problems and generally reported that hosting research was a positive experience. Jury pools represent a viable and relatively untapped source of research participants. Many courts are open to the possibility of hosting research but have never been asked to do so. Both researchers and court officials should be reassured by the positive experiences of courts that have hosted research.

Humans↗
PubMed2000

Genome scan identifies a locus affecting gamma-globin level in human beta-cluster YAC transgenic mice.

Genetic factors affecting postnatal gamma-globin expression--a major modifier of the severity of both beta-thalassemia and sickle cell anemia--have been difficult to study. This is especially so in mice, an organism lacking a globin gene with an expression pattern equivalent to that of human gamma-globin. To model the human beta-cluster in mice, with the goal of screening for loci affecting human gamma-globin expression in vivo, we introduced a human beta-globin cluster YAC transgene into the genome of FVB/N mice. The beta-cluster contained a Greek hereditary persistence of fetal hemoglobin (HPFH) gamma allele, resulting in postnatal expression of human gamma-globin in transgenic mice. The level of human gamma-globin for various F1 hybrids derived from crosses between the FVB/N transgenics and other inbred mouse strains was assessed. The gamma-globin level of the (C3HeB/FeJ x FVB/N)F1 transgenic mice was noted to be significantly elevated. To map genes affecting postnatal y-globin expression, we performed a 20-centiMorgan (cM) genome scan of a (C3HeB/FeJ x FVB/N)F1 transgenics x FVB/N backcross, followed by high-resolution marker analysis of promising loci. From this analysis we mapped a locus within an 18-cM interval of mouse Chromosome (Chr) 1 (LOD = 4.3) that contributes 10.9% of variation in gamma-globin level. Combining transgenic modeling of the human beta-globin gene cluster with quantitative trait analysis, we have identified and mapped a murine locus that impacts on human gamma-globin level in vivo.

Animals↗
PubMed2000

Evaluation of photo radar program in British Columbia.

This article presents the results of an evaluation of the speed and traffic safety effects of the photo radar program in British Columbia (BC) after 1 year of full operation. Traffic speed data were collected from the photo radar units and from induction loops installed across the province. Traffic collision and injury data were obtained from police investigation reports and from BC ambulance services records. The study employed a number of analytical frameworks, including simple before and after comparison, time-series cross-sectional analysis, and interrupted time series analysis. The study revealed a dramatic reduction of speed at photo radar deployment sites. A reduction of 2.4 km/h in mean speed was also observed at selected monitoring sites where enforcement was not likely to be present. The reduction of speed was accompanied by a decrease in collisions, injuries and fatalities. The analysis found a 25% reduction in daytime unsafe speed related collisions, an 11% reduction in daytime traffic collision victims carried by ambulances and a 17%, reduction in daytime traffic collision fatalities.

Acceleration↗
PubMed2000

Misdiagnosis of epilepsy: many seizure-like attacks have a cardiovascular cause.

OBJECTIVES: We sought to investigate the value of cardiovascular tests to diagnose convulsive syncope in patients with apparent treatment-resistant epilepsy. BACKGROUND: As many as 20% to 30% of epileptics may have been misdiagnosed. Many of these patients may have cardiovascular syncope, with abnormal movements due to cerebral hypoxia, which may be difficult to differentiate from epilepsy on clinical grounds. METHODS: Seventy-four patients (33 men, mean age 38.9 +/- 18 years [range 16 to 77]) who were previously diagnosed with epilepsy were studied. Inclusion criteria included continued attacks despite adequate anticonvulsant drug treatment (n = 36) or uncertainty about the diagnosis of epilepsy, on the basis of the clinical description of the seizures (n = 38). Each patient underwent a head-up tilt test and carotid sinus massage during continuous electrocardiography, electroencephalography and blood pressure monitoring. Ten patients subsequently underwent long-term electrocardiographic (ECG) monitoring with an implantable loop recorder. RESULTS: In total, an alternative diagnosis was found in 31 patients (41.9%), including 13 (36.1%) of 36 patients taking an anticonvulsant medication. Nineteen patients (25.7%) developed profound hypotension or bradycardia during the head-up tilt test, confirming the diagnosis of vasovagal syncope. One other patient had a typical vasovagal reaction during intravenous cannulation. Two patients developed psychogenic symptoms during the head-up tilt test. Seven patients (9.5%) had significant ECG pauses during carotid sinus massage. In two patients, episodes of prolonged bradycardia correlated precisely with seizures according to the insertable ECG recorder. CONCLUSIONS: A simple, noninvasive cardiovascular evaluation may identify an alternative diagnosis in many patients with apparent epilepsy and should be considered early in the management of patients with convulsive blackouts.

Adolescent↗
PubMed2000

Application of directly coupled HPLC-NMR-MS/MS to the identification of metabolites of 5-trifluoromethylpyridone (2-hydroxy-5-trifluoromethylpyridine) in hydroponically grown plants.

Directly coupled HPLC-NMR-MS was used to characterize two major metabolites of 5-trifluoromethylpyridone (2-hydroxy-5-trifluoromethylpyridine), a model compound for herbicides, after it had been dosed into hydroponically grown maize plants. The combination of NMR and MS data allowed the identification of both of these metabolites, namely, the N-glucoside and O-malonylglucoside conjugates of the parent pyridone. This work demonstrates the efficiency and the potential application of HPLC-NMR-MS to the investigation of the metabolism of agrochemicals. The work also indicates that combination of the use of hydroponically grown plants and directly coupled HPLC-NMR-MS allows rapid identification of metabolites with little sample preparation.

Chromatography, High Pressure Liquid↗
PubMed2000

High-resolution field shaping utilizing a masked multileaf collimator.

Multileaf collimators (MLCs) have become an important tool in the modern radiotherapy department. However, the current limit of resolution (1 cm at isocentre) can be too coarse for acceptable shielding of all fields. A number of mini- and micro-MLCs have been developed, with thinner leaves to achieve approved resolution. Currently however, such devices are limited to modest field sizes and stereotactic applications. This paper proposes a new method of high-resolution beam collimation by use of a tertiary grid collimator situated below the conventional MLC. The width of each slit in the grid is a submultiple of the MLC width. A composite shaped field is thus built up from a series of subfields, with the main MLC defining the length of each strip within each subfield. Presented here are initial findings using a prototype device. The beam uniformity achievable with such a device was examined by measuring transmission profiles through the grid using a diode. Profiles thus measured were then copied and superposed to generate composite beams, from which the uniformity achievable could be assessed. With the average dose across the profile normalized to 100%, hot spots up to 5.0% and troughs of 3% were identified for a composite beam of 2 x 5.0 mm grids, as measured at Dmax for a 6 MV beam. For a beam composed from 4 x 2.5 mm grids, the maximum across the profile was 3.0% above the average, and the minimum 2.5% below. Actual composite profiles were also formed using the integrating properties of film, with the subfield indexing performed using an engineering positioning stage. The beam uniformity for these fields compared well with that achieved in theory using the diode measurements. Finally sine wave patterns were generated to demonstrate the potential improvements in field shaping and conformity using this device as opposed to the conventional MLC alone. The scalloping effect on the field edge commonly seen on MLC fields was appreciably reduced by use of 2 x 5.0 mm grids, and still further by the use of 4 x 2.5 mm grids, as would be expected. This was also achieved with a small or negligible broadening of the beam penumbra as measured at Dmax.

Biophysical Phenomena↗