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A Walker

Publications and source records attributed to A Walker.

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

Spatial variability in the degradation rate of isoproturon in soil.

Thirty samples of soil were taken at 50-m intersections on a grid pattern over an area of 250 x 200 m within a single field with nominally uniform soil characteristics. Incubations of isoproturon (3-(4-isopropylphenyl)-1,1-dimethylurea) under standard conditions (15 degrees C; -33 kPa soil water potential) indicated considerable variation in degradation rate of the herbicide, with the time to 50% loss (DT50) varying from 6.5 to 30 days. The kinetics of degradation also varied between the sub-samples of soil. In many of them, there was an exponential decline in isoproturon residues; in others, exponential loss was followed by more rapid rates of decline; in a few soil samples, rapid rates of loss began shortly after the start of the incubations. In more detailed studies with soils from a smaller number of sub-sites (20), measurements were again made of isoproturon degradation rate, and the soils were analysed for organic matter content, pH, and nutrient status (N, P, K). Measurements were also made of isoproturon adsorption by the soils and of soil microbial biomass. Patterns of microbial metabolism were assessed using 95 substrates in Biolog GN plates. Soils showing rapid biodegradation were generally of higher pH and contained more available potassium than those showing slower degradation rates. They also had a larger microbial biomass and greater microbial metabolic diversity as determined by substrate utilisation on Biolog GN plates. The implications of the results for the efficacy and environmental behaviour of isoproturon are discussed.

Adsorption↗
PubMed2001

Ensuring safety of patients receiving sedation for procedures: evaluation of clinical practice guidelines.

BACKGROUND: In 1995 The Johns Hopkins Hospital in Baltimore convened an interdisciplinary task force to evaluate sedation practices, create a comprehensive set of sedation guidelines, and evaluate patient safety outcomes following guideline implementation. METHODOLOGY: Baseline data were collected on all procedures in which sedation was administered by a nonanesthesiologist for a 6-month period, using scanning technology to automate data entry. Sedation practices were reviewed, and four critical events were examined: unresponsiveness, obstructed airway, airway placement, and cardiopulmonary resuscitation (CPR). In 1998 data collection procedures were repeated to evaluate the impact of the guidelines on sedation practices and patient safety outcomes. RESULTS: In 1995 sedation practices varied, and one or more critical events occurred in 45 (1.4%) of 3,255 procedures. Steps taken included development and dissemination of a clinical sedation guideline, including monitoring criteria to guide nonanesthesiologists, and evaluation planning. In 1998 sedation practices were more consistent. One or more critical events occurred in 50 (1.6%) of 3,134 procedures, representing a small increase in critical events from 1995. More events of unresponsiveness were identified, and no event required CPR. Although not statistically significant, this trend suggests that critical events were being identified earlier, preventing patients from progressing to a more serious event requiring CPR. Steps taken included further refinement of clinical practice guidelines and establishment of ongoing monitoring. CONCLUSIONS: Standardization of sedation practices is a complex and resource-intensive activity, requiring ongoing oversight and monitoring. Commitment from medical staff, nursing staff, and administration is essential to successful implementation of sedation guidelines.

Academic Medical Centers↗
PubMed2001

An unusual case.

Explore the source record for details and available documents.

Adult↗
PubMed2001

Chiropractic and a new taxonomy of primary care activities.

OBJECTIVE: To specify the procedural and cognitive content of primary care and to discuss potential chiropractic primary care roles. DATA COLLECTION: Data were collected through use of two expert panels and a consensus process to create a list of primary care activities. The first panel was an interdisciplinary mix of physicians, mainly allopathic ones; most of the members of the second panel were chiropractors. Each panel rated primary care activities across a number of dimensions, such as importance for good health, frequency in a typical office-based practice, necessity for medical doctor involvement in the activity, competence of the majority of chiropractic physicians, and interest among chiropractors in performing the activity. RESULTS: There was no real difference between the panels in terms of taxonomy scope or importance of the activities for good health. Many of the activities are performed more frequently in a typical medical office than in a typical chiropractic office. With respect to a set of primary care activities that occur daily in medical offices, chiropractors are able to make diagnoses in 92% of the activities and to make therapeutic contributions in more than 50% of the activities. Medical doctor involvement was perceived as required more frequently by the chiropractic panel than by the interdisciplinary panel. Moreover, chiropractors' interests and self-assessments of competence showed some limits with regard to their assumption of total care for some frequently occurring primary care activities. CONCLUSIONS: The most important finding of this activity is the overriding sense of agreement between allopathic and chiropractic physicians in terms of the scope of primary care activities, suggesting that there is opportunity for chiropractors and medical doctors to work together on patient care and organizational strategy. However, the levels of self-assessed competence and interest on the part of chiropractors for many frequently occurring primary care activities reveal some important limits for assumption of total primary care.

Chiropractic↗
PubMed2001

Bilateral orbitomedial leucotomy for obsessive-compulsive disorder: a single-case study using positron emission tomography.

OBJECTIVE: The objective of this report is to correlate the clinical outcome of neurosurgery for obsessive-compulsive disorder (OCD) with regional cerebral glucose metabolic changes. CLINICAL PICTURE: The patient was a 37-year-old female patient with severe and intractable OCD. TREATMENT: The patient was treated with bilateral stereotactic lesions in the frontal white matter superior to the orbito-medial cortex. OUTCOME: She had a remarkable improvement in her obsessive-compulsive symptoms, which was sustained up to 3 years of follow up. A positron emission tomography (PET) scan performed 18 days after surgery demonstrated an obvious reduction of metabolism in the caudate head, anterior cingulate and orbital, medial and lateral prefrontal cortices and the thalamus. At 1 year postsurgery, metabolic rate was still reduced in the anterior cingulate gyrus, caudate and thalamus compared with preoperative baseline. The patient demonstrated no long-term cognitive effects of the surgery. CONCLUSIONS: This case supports some of the cortical-subcortical circuit dysfunction models of OCD and argues for the further evaluation of neurosurgery for the treatment of a severe and intractable disorder.

Adult↗
PubMed2001

Degradation of substituted phenylurea herbicides by Arthrobacter globiformis strain D47 and characterization of a plasmid-associated hydrolase gene, puhA.

Arthrobacter globiformis D47 was shown to degrade a range of substituted phenylurea herbicides in soil. This strain contained two plasmids of approximately 47 kb (pHRIM620) and 34 kb (pHRIM621). Plasmid-curing experiments produced plasmid-free strains as well as strains containing either the 47- or the 34-kb plasmid. The strains were tested for their ability to degrade diuron, which demonstrated that the degradative genes were located on the 47-kb plasmid. Studies on the growth of these strains indicated that the ability to degrade diuron did not offer a selective advantage to A. globiformis D47 on minimal medium designed to contain the herbicide as a sole carbon source. The location of the genes on a plasmid and a lack of selection would explain why the degradative phenotype, as with many other pesticide-degrading bacteria, can be lost on subculture. A 22-kb EcoRI fragment of plasmid pHRIM620 was expressed in Escherichia coli and enabled cells to degrade diuron. Transposon mutagenesis of this fragment identified one open reading frame that was essential for enzyme activity. A smaller subclone of this gene (2.5 kb) expressed in E. coli coded for the protein that degraded diuron. This gene and its predicted protein sequence showed only a low level of protein identity (25% over ca. 440 amino acids) to other database sequences and was named after the enzyme it encoded, phenylurea hydrolase (puhA gene).

Amidohydrolases↗
PubMed2001

Characterization of human cytomegalovirus strains by analysis of short tandem repeat polymorphisms.

Human cytomegalovirus (HCMV) strains display genetic polymorphisms, and these polymorphisms can be analyzed to study viral transmission and pathogenesis. Recently, short tandem repeat (STR) length polymorphisms have been identified in the HCMV genome. We assessed the utility of STRs in characterizing HCMV strains and found that a multiplexed PCR assay using primers based upon these STRs accurately maps HCMV strains. Using primers for 10 microsatellite regions, the STR profiles of 44 wild-type and 2 laboratory strains of HCMV were characterized. The results of STR analysis were compared with those for strain characterization using nucleotide sequencing and restriction fragment length polymorphism analysis. In each instance, STR analysis accurately and specifically identified strains that were indistinguishable or distinct by conventional molecular analysis. Analysis of short tandem repeats also detected polymorphisms that supported simultaneous excretion of two HCMV strains. These results indicate that STR analysis allows rapid, precise molecular characterization of HCMV strains.

Adult↗
PubMed2001

The Lazarus phenomenon following recreational drug use.

A case is reported of the Lazarus phenomenon (the return of spontaneous circulation after cardiopulmonary resuscitation had been abandoned) in a patient following recreational drug use. The implications for management of cardiac arrest in the emergency department are discussed.

Adult↗
PubMed2001

Who cares for the patient with head injury now?

OBJECTIVE: A recent report on head injury management from the Royal College of Surgeons of England suggests that surgeons are unsuited to the inpatient care of head injuries (ICHI) and should hand over responsibility entirely to neurosurgeons and accident and emergency (A&E) specialists. This prompted a survey of A&E consultants to establish their opinions on the current and future practice of head injury care. METHODS: Questionnaires were sent to consultant members of the British Association for Accident and Emergency medicine. Of a possible 256 A&E departments from Great Britain and Ireland with over 20 000 annual new attenders 206 (80%) replied. RESULTS: General surgeons contribute to ICHI for adults in 107 of 206 hospitals (52%) compared with orthopaedic surgeons in 73 of 206 (35%) and A&E consultants in 71 of 206 (34%). There was frequent criticism that surgeons are uninterested in head injury care. Fifty nine units (30%) commented on the lack of neurosurgery beds and difficulties experienced in getting patients accepted. Few hospitals seem to have well integrated rehabilitation or follow up services targeted at head injury. One in six patients with head injury admitted to a general hospital or observation ward remain after 48 hours and one in 20 stay beyond one week. Of the 132 A&E units without responsibility for ICHI 54 (41%) either wish to take on this responsibility or are willing to do so if the necessary resources are first put in place. The perceived net revenue cost required to allow 67 A&E units to take on ICHI is about 12.5 million pounds per year. This does not include the cost of further care after 48 hours, follow up or rehabilitation. CONCLUSION: Only one third of A&E units at present have even part of the ICHI role recommended in the RCS report; another third are prepared to accept a new role if training and resources are provided and support is forthcoming from other specialists to take over the care after 48 hours; the remaining third are unwilling to accept responsibility for ICHI.

Craniocerebral Trauma↗
PubMed2001

Central infusions of the recombinant human prolactin receptor antagonist, S179D-PRL, delay the onset of maternal behavior in steroid-primed, nulliparous female rats.

The expression of maternal behavior in the newly parturient rat is under endocrine regulation. Blocking endogenous PRL secretion with bromocriptine delays the normal rapid expression of maternal care shown toward foster young in steroid-primed virgin female rats. The recent development of the PRL receptor antagonist S179D-PRL, a mutant of human PRL in which the serine residue at the 179 position is replaced with aspartate, provides a potentially useful tool to examine the role of PRL in neural processing. In the present report, three experiments were conducted that examined the effects of this PRL antagonist on the induction of maternal behavior. In each experiment, ovariectomized, nulliparous rats were treated sequentially with SILASTIC capsules implanted sc with progesterone (days 1-11) and estradiol (days 11-17), a treatment that stimulates a rapid onset of maternal behavior in virgin rats. On day 11, females were implanted with Alzet miniosmotic pumps connected to cannulae directed unilaterally at the lateral ventricle (Exp 1) or bilaterally at the medial preoptic area (MPOA; Exp 2 and 3). Pumps contained either doses of S179D-PRL (0.115 or 1.15 mg/ml; Exp 1 and 2), wild-type human PRL (1.15 mg/ml; Exp 3), or the saline vehicle (Exp 1-3). Testing for maternal behavior began on day 12, a day after pump insertion, and animals were tested daily for 6 days. Latencies to contact, retrieve, and group foster test young were recorded. Administration of both the high and low doses of S179D-PRL infused into the lateral ventricle (Exp 1) or MPOA (Exp 2) significantly delayed the onset of maternal behavior. In contrast, MPOA infusions of the control hormone, wild-type human PRL, in Exp 3 did not delay the onset of maternal behavior. These findings support the concept that the effects of S179D-PRL are caused by its actions as a PRL receptor antagonist rather than by a nonspecific effect of the protein. Overall, these results demonstrate the effectiveness of S179D-PRL acting at the level of the central nervous system (and, more specifically, within the MPOA) to regulate maternal behavior, a PRL-mediated response.

Animals↗
PubMed2001

Limitation of the Vitros dry-slide technique in measuring high concentrations of salicylate in plasma.

The linearity of the Vitros dry-slide method for plasma salicylate was assessed in two ways: serial concentrations of sodium salicylate were added to fresh lithium heparin plasma, and the salicylate was determined both neat and in dilution. Vitros salicylate results submitted to the Heathcontrol External Quality Assessment Scheme were compared to the spike value. Similar loss of linearity was observed in both cases. Serious salicylate overdosage requiring specific clinical treatment may have been underestimated.

Blood Chemical Analysis↗
PubMed2001

Trajectory, transition and vulnerability in adult medical-surgical patients: a framework for understanding in-hospital convalescence.

Relatively recent changes in health care have seen shorter hospital stays and a considerable increase in day-only admissions, anticipated to involve 60% of all patients admitted for surgery and/or investigations within the next couple of years. Surprisingly little is known about the experiences of the approximately 40% of patients who will begin to convalesce in hospital following illness, trauma or surgery. Findings from a qualitative study, briefly reported here, identified a sense of vulnerability in transition as a significant discomfort. By examining assumptions underlying the care of patients recovering in hospital, the nexus between system-determined care trajectories transition, and patient vulnerability can be identified and problems suitably addressed.

Australia↗
PubMed2001

Clinical grading of corneal staining of non-contact lens wearers.

To distinguish normal from pathological corneal fluorescein staining requires knowledge of background levels of staining among otherwise healthy individuals. Corneal staining of 102 non-contact lens wearing subjects was assessed using a photographic grading scale that uses a generic (0 to 4) scale to score corneal staining. Some degree of corneal staining was found on 79% of the corneas. Low inter-observer variability suggests that the corneal staining grading scale can be used successfully with decimal rather than integer scale increments.

Adolescent↗
PubMed2001

Interaction of glutathione S-transferase M1 and T1 genotypes and malignant melanoma.

The mu and theta classes of glutathione S-transferases (GST) may affect the development of cutaneous malignant melanoma (CMM) by decreasing cellular oxidative stress in skin. These isozymes are absent in a large proportion of the population because of germ-line homozygous deletions in the genes encoding GSTM1 and GSTT1. To determine the association between GSTM1 and GSTT1 homozygous deletions (GSTM1 null and GSTT1 null, respectively) and CMM, we studied 212 patients with CMM, 150 patients with CMM and dysplastic nevi (DN), 147 patients with DN alone, and 124 healthy persons without CMM or DN. Comparing CMM cases (n = 362) to participants without CMM (n = 271), we found no association with GSTM1 null [odds ratio (OR), 1.2; 95% confidence interval (CI), 0.86-1.6] or GSTT1 null (OR, 0.82; 95% CI, 0.56-1.2), either independently or in combination (OR, 1.4; 95% CI, 0.81-2.2), after adjusting for age. However, among the subset of participants with red or blond hair, those with CMM were twice as likely to carry GSTM1 null (OR, 2.2; 95% CI, 1.2-4.2) and nearly 10-fold more likely to carry both GSTM1 null and GSTT1 null (OR, 9.5; 95% CI, 1.2-73) compared with those without CMM. These data suggest that among persons with hair colors traditionally associated with increased risk for melanoma, absence of both GSTM1 and GSTT1 may act to further elevate CMM risk.

Adult↗
PubMed2001

The 'real-world' impact of improved diagnostic techniques for Chlamydia trachomatis infection in Glasgow.

In April 1997, the main chlamydia laboratory in Glasgow introduced ligase chain reaction (LCR) as its standard diagnostic test. The diagnostic effectiveness and health economic impact of introduction of LCR testing was assessed. Between April 1996 to March 2000, results of all chlamydia detection tests on genital specimens sent from general practitioners and the two main sexual healthcare providers (Genitourinary Medicine and Family Planning services) were reviewed. A preliminary economic assessment, inclusive of staff, reagents, consumables and laboratory overheads was conducted. Overall, testing activity increased four and a half times between 1996-97 and 1999-2000; the proportionate rise was greatest in general practice. Although chlamydia testing in both genders increased over the review period, testing activity rose disproportionately in women (59%, compared with a 31% increase in men). The overall Chlamydia trachomatis detection rate rose from 4.8% in 1996-97 to 7.8% in 1999-2000. Following introduction of LCR testing, an estimated additional 331 men and 844 women were diagnosed during the study period. The cost per additional diagnosis made was estimated at 162 Pounds for men and 263 Pounds for women. Substantial health gains are likely to be achieved, at both an individual and public health level, as a result of introduction of LCR testing for genital chlamydial infection.

Adolescent↗