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Biomedical subjects

A Walker

Publications and source records attributed to A Walker.

At least 127 records · Page 7Linked to original sources
PubMed1999

Racial differences in bone mineral density and bone loss among end-stage renal disease patients.

Although black patients without end-stage renal disease (ESRD) have a greater bone mineral density (BMD) than whites, the impact of race on BMD among patients with ESRD who are likely to have varying degrees of renal osteodystrophy is not known. We undertook a cohort study of 106 hemodialysis patients comparing BMD and bone loss between black and white patients with ESRD to determine if black patients have a greater BMD and less bone loss than white patients with ESRD. BMD was determined by dual-energy radiograph absorptiometry (DEXA). Osteopenia was defined as greater than 1 standard deviation (SD) less than the mean of peak bone mass (T score <-1), and osteoporosis was defined as greater than 2.5 SDs less than the mean of peak bone mass (T score <-2.5). The association between BMD and race was estimated using linear regression. The risk for osteopenia among black compared with white patients was calculated using logistic regression. Black patients were similar to white patients with respect to all characteristics noted, except black patients were less likely to be men (69.7% v 49. 4%) and tended to have greater intact parathyroid hormone (PTH) values (mean, 403.2 +/- 384.5 pg/mL v 161.4 +/- 129.0 pg/mL). Compared with whites, the BMD of blacks was a mean of 1.15 (95% confidence interval [CI], 0.54 to 1.78) SDs greater at the femoral neck after adjusting for age, PTH level, and sex. The percentage of bone loss per year was similar between blacks and whites. The risk for osteopenia among blacks was significantly less than that among whites (odds ratio = 0.15; 95% CI, 0.04 to 0.59) after adjusting for age, sex, and PTH level. Black patients with ESRD have a greater BMD and are at decreased risk for osteopenia compared with whites, independent of renal osteodystrophy. When considering bone disease among patients with ESRD, physicians should also consider osteoporosis and the impact of race on BMD.

Bone Density↗
PubMed1999

Low rates of hospitalization for asthma among Aboriginal children compared to non-Aboriginal children of the top end of the northern territory.

OBJECTIVE: To determine the hospitalization rates from asthma for Aboriginal and Torres Strait Islander (ATSI) and non-Aboriginal (non-ATSI) children in the 'top end' of the Northern Territory and to determine the proportion of hospitalizations due to asthma. METHODOLOGY: A retrospective review was undertaken of separation data from the Royal Darwin Hospital for the period July 1991 to June 1997. All children aged 1-9 years residing in the Darwin urban or rural district were included, with asthma identified by the International Classification of Diseases Version 9 codes 493.0-493.9. RESULTS: The overall average annual hospitalization rate per 1000 population with a principal diagnosis of asthma for ATSI children from rural areas (ATSI-rural) was 2.6, 4.7 for ATSI children from urban areas (ATSI-urban) and 5.5 for non-ATSI children. These hospitalization rates were significantly different between ATSI and non-ATSI children (rate ratio 0.72, 95% CI 0.59-0.86). On stratification for residence, the rates were significantly different between ATSI-rural and non-ATSI children (rate ratio 0.61, 95% CI 0. 47-0.80) but not different between rural and urban dwelling ATSI children (rate ratio 0.76, 95% CI 0.54-1.07) or between ATSI-urban children and non-ATSI children (rate ratio 0.81, 95% CI 0.63-1.03). Asthma was diagnosed in 6.5% of ATSI admissions (4.0% for ATSI-rural and 13.8% for ATSI-urban) and 12.7% of non-ATSI admissions. CONCLUSION: The hospitalization rate for ATSI children with asthma was significantly lower than for non-ATSI children. Asthma plays a far less significant role in the spectrum of disease affecting hospitalized ATSI children compared to non-ATSI children. There are significant differences in disease frequency between urban and rural resident ATSI children but less marked differences between urban resident ATSI children and non-ATSI children. Further study is required if the underlying causes behind these differences are to be determined.

Asthma↗
PubMed1999

Neurological features of cerebral malaria in Nigerian children.

Cerebral malaria is one of the commonest causes of an acute neurological syndrome in malaria-endemic areas. However, there are few detailed reports of findings on clinical neurological examination of the condition. The neurological features of cerebral malaria in 103 children aged 5 years or less were studied in Ibadan, Nigeria, an area of high malaria transmission. The correlation of these features with prognosis was also studied. Convulsions occurred in 87% of subjects and were in most cases of a generalized tonic-clinic nature. Abnormalities of posture were observed in 41%, abnormal tone in 70% and abnormal deep tendon reflexes in 74%. Absent corneal reflexes were found in about 14%. The time interval between the last seizure episode and presentation in hospital, abnormal posture (decerebrate or decorticate), absence of corneal reflex and depth and duration of coma were indicators of poor prognosis. In this study, cerebral malaria presented with non-specific features of diffuse, symmetrical, upper motor neurone dysfunction, and some specific neurological features were associated with poor prognosis. It is important that cerebral malaria be considered in any child with features of acute encephalopathy in a malaria-endemic area. Careful clinical examination of such children is essential as neurological features of the condition may provide a clue to prognosis.

Child, Preschool↗
PubMed1999

Nurses' perception and experiences of advocacy.

This small qualitative research study, undertaken for a Bachelor (Honours) Course, was aimed at discovering nurses' perceptions and experiences of advocacy, through focused, in-depth interviews. Thematic analysis identified seven major themes: advocacy as a moral obligation, knowing the patient, triggers to becoming an advocate, considering the consequences, the difficulties of advocating, becoming an effective advocate and outcomes of advocacy. When further examined, these themes suggested that advocacy is a process rather than an event. The themes are supported from the data and the steps in the process are outlined and offered as a tentative model of nursing advocacy. This study increases understanding of advocacy from a nursing perspective and may help minimise the difficulties of enacting an advocacy role.

Adult↗
PubMed1999

Neurodevelopmental and neurobehavioral sequelae of selected substances of abuse and psychiatric medications in utero.

Alcohol exposure in utero affects growth and morphology, and produces FAS, adverse cognitive outcomes, and poorer linguistic abilities and deficits in attention and memory. Maternal smoking, which is widespread in pregnancy, has been associated with physical, cognitive, and behavioral effects in offspring. The effects of fetal exposure to cocaine are more controversial, but increasing evidence identifies a pattern of decreased neonatal head circumference, decreased adaptability to stress, including a disruption in the habituation response in infants, and impaired attention. The literature on the effects of in utero exposure to marijuana is thus far inconclusive, but there is compelling evidence for its producing decreased birth weight and length and deleterious cognitive and attentional effects in some preschool and early school-age samples. Of the widely prescribed medications used in psychiatric practice, evidence for the deleterious effects of lithium and the anticonvulsants carbamazepine and depakote is well-established and compelling. More prospective studies are required before the safety of the atypical antipsychotics and the newer antidepressants is established. Difficulties of standardizing amount, timing, and patterns of use, as well as the confounding effect of the risk factors, must be carefully considered when interpreting the results of outcome studies, especially those regarding substances of abuse.

Anticonvulsants↗
PubMed1999

Measuring progress towards a primary care-led NHS.

BACKGROUND: The push towards a 'primary care-led' National Health Service (NHS) has far-reaching implications for the future structure of the NHS. The policy involves both a growing emphasis on the role of primary care practitioners in the commissioning of health services, and a change from hospital to primary and community settings for a range of services and procedures. Although the terminology has changed, this emphasis remains in the recent Scottish Health Service White Paper and its English counterpart. AIM: To consider three questions in relation to this policy goal. First, does the evidence base support the changes? Secondly, what is the scale of the changes that have occurred? Thirdly, what are the barriers to the development of a primary care-led NHS? METHOD: Programme budgets were compiled to assess changes over time in the balance of NHS resource allocation with respect to primary and secondary care. Total NHS revenue expenditure for the 15 Scottish health boards was grouped into four blocks or 'programmes': primary care, secondary care, community services, and a residual. The study period was 1991/2 to 1995/6. Expenditure data were supplied by the Scottish Office. RESULTS: Ambiguity of definitions and the absence of good data cause methodological difficulties in evaluating the scale and the appropriateness of the shift. The data that are available suggest that, at the aggregate level, there have been changes over time in the balance of resource allocation between care settings: relative investment into primary care has increased. It would appear that this investment is relatively small and from growth money rather than a 'shift' from secondary care. In addition, the impact of GP-led commissioning is variable but limited. CONCLUSION: General practitioners' (GPs') attitudes to the policy suggest that progress towards a primary care-led NHS will continue to be patchy. The limited shift to date, alongside evidence of ambivalent attitudes to the shift on the part of GPs, suggest that this is a policy objective that may not be achieved.

Delivery of Health Care↗
PubMed1999

Implementation of a national guideline on prophylaxis of venous thromboembolism: a survey of acute services in Scotland. Thromboembolism Prevention Evaluation Study Group.

BACKGROUND: Deep vein thrombosis (DVT) and pulmonary embolism (PE) are major complications for hospital patients in developed countries. In 1995, the Scottish Intercollegiate Guidelines Network (SIGN) published an evidence-based guideline to encourage the appropriate use of prophylaxis for DVT among hospitalised patients at risk. The guideline was widely distributed within the NHS in Scotland; however, it is not clear what actions trusts have taken to implement it. OBJECTIVE: To investigate the type and extent of DVT guideline implementation activities in acute trusts in Scotland. METHOD: A semi-structured telephone interview with senior clinical audit staff in those trusts with acute services in Scotland. RESULTS: Twenty-nine of the 30 trusts approached participated in the survey (97%). A range of responses to the guideline were reported, including development of local protocols (n = 20), audit of DVT prophylaxis (n = 19), patient specific reminders (n = 13) and provision of a specialist DVT adviser (n = 3). Overall, 25 of the trusts had undertaken guideline development and dissemination activities, and 17 were involved in more active guideline implementation strategies. CONCLUSIONS: The majority of acute trusts in Scotland have responded to the SIGN guideline, usually through the development of local protocols. Strategies to implement the guideline or local protocol are less common. Further guidance is needed on this in the next edition of the guideline.

Clinical Protocols↗
PubMed1998

New specimens and confirmation of an early age for Australopithecus anamensis.

The discovery of Australopithecus anamensis fossils from strata lying between tephra dated at 4.17 and 4.12 million years ago, and from slightly higher strata not well constrained in age by overlying dated units, provoked the claim that more than one species might be represented: it was suggested that the stratigraphically higher fossils, which include the important tibia, humerus and a large, presumed male, mandible (KNM-KP 29287), might belong to a later, more derived hominid. We have recovered new fossils from Kanapoi and Allia Bay, Kenya, during field work in 1995-1997 that confirm the primitive status of Australopithecus anamensis, the earliest species of Australopithecus. Isotope dating confirms A. anamensis' intermediate age as being between those of Ardipithecus ramidus and Australopithecus afarensis. New specimens of maxilla, mandible and capitate show that this species is demonstrably more primitive than A. afarensis. A lower first deciduous molar (dm 1) is intermediate in morphology between that reported for Ardipithecus ramidus and A. afarensis. Single-crystal 40Ar-39Ar age determinations on the Kanapoi Tuff show that, except for a large mandible, all of the hominid fossils from Kanapoi are from sediments deposited between 4.17+/-0.03 and 4.07+/-0.02 million years ago.

Animals↗
PubMed1998

Safety and immunogenicity of a candidate therapeutic vaccine, p24 virus-like particle, combined with zidovudine, in asymptomatic subjects. Community HIV Research Network Investigators.

OBJECTIVES: To evaluate the impact of therapeutic immunization with p24 virus-like particle (VLP) and zidovudine (ZDV) on p24 antibody titre (primary endpoint), CD4+ cell counts, cellular responses to the immunogen and recall antigens, and viral load (secondary endpoints) in subjects with asymptomatic HIV infection and CD4+ counts greater than 400 x 10(6) cells/l. DESIGN: A double dummy, double-blind randomized placebo-controlled Phase II trial of the therapeutic vaccine p24-VLP, with or without ZDV. METHODS: ZDV-naive subjects were randomized to one of three groups for 6 months: group A, ZDV 200 mg three times daily plus intramuscular administration of alum adjuvant monthly; group B, ZDV 200 mg three times daily plus p24-VLP (500 microg) in intramuscular alum monthly; group C, placebo capsules plus p24-VLP (500 microg) in intramuscular alum monthly. Subjects were followed for a further 6 months. RESULTS: Sixty-one patients received vaccinations. The mean CD4+ cell counts pretherapy for groups A, B, and C were 605 +/- 25, 668 +/- 43, and 583 +/- 30 x 10(6) cells/l, respectively. Treatment was well tolerated. At both 24 and 52 weeks there were no significant differences between the treatment groups in terms of antibody responses to p24, CD4+ or CD8+ cell counts, viral load, T-cell responses to p24, p17, recall antigen or mitogen, or markers of immune activation, despite induction of antibody and proliferative responses to the carrier protein of the vaccine. CONCLUSION: Vaccination with p24-VLP was well tolerated. p24-VLP either alone or in combination with ZDV did not significantly alter either antibody or proliferative responses to p24, or CD4+ cell number, immune activation or viral load over 12 months.

AIDS Vaccines↗
PubMed1998

Ocular disorders in users of H2 antagonists and of omeprazole.

We have conducted a cohort study of users of omeprazole and H(2) antagonists in Italy to investigate whether the peroral use of these drugs may be associated with an increased incidence of ocular disorders leading to loss of vision. We have used the Sistema Informativo Sanitario Regionale (SISR database) in Friuli-Venezia-Giulia to identify all subjects who received at least one prescription for cimetidine, famotidine, niperotidine, nizatidine, omeprazole, ranitidine or roxatidine between 1 January 1991 and 31 December 1994. We have identified all hospital admissions for serious vascular or inflammatory ocular disorders following any such prescription, reviewed and validated all medical records. There were 71,108 users of any of the study drugs, contributing a total of 101,827 person years of observation. Seven cases of serious eye disorders were identified, giving an annual incidence rate of 7/100,000 persons. By comparison to non-users, the incidence rate ratio for current users of all of the study drugs together was 0, with a 95% confidence interval of 0 to 2.1. By comparison to non-users, the incidence rate ratio for past users was 0.47 (95% CI: 0.06-2.4). Our data are consistent with previous studies and add weight to the general impression of the ocular safety of these drugs.

Journal Article↗
PubMed1998

Comparative dental development and microstructure of Proconsul teeth from Rusinga Island, Kenya.

Eighteen histological sections were prepared from eleven teeth attributed to Proconsul heseloni and two molar teeth attributed to Proconsul nyanzae. Measurements of spacings and counts of daily incremental markings in both enamel and dentine were possible in the majority of these tooth sections. Measurements of the spacings and angles to the enamel dentine junction (EDJ) of regular striae of Retzius and of equivalent markings in dentine were also made. In addition to these measurements, counts of perikymata were made on replicas of all other Proconsul teeth housed in the National Museum of Kenya, Nairobi, that preserved good perikymata on any aspect of their tooth surface. The sequence of crown formation in Proconsul and the crown formation times of the enamel and dentine were estimated from these data. In addition, the rates of root extension were estimated using the formula derived for this purpose by Shellis (Archs. oral Biol. 29, 697-705, 1984) and estimates of the total period of root formation subsequently made for premolar and molar teeth based on measurements of root length. A composite chart of dental development for P. heseloni is presented which suggests M3 root completion was between six and seven years of age. In general Proconsul molar teeth have high stria angles to the EDJ, a high ratio of enamel formed with respect of dentine formed at the same time, median values of rates of enamel formation close to the EDJ in excess of 4 microns per day and the occasional presence of "S-shaped" striae in the lateral enamel. There is no evidence to suggest that Proconsul from Rusinga Island, Kenya, had relatively thin enamel on molar or premolar teeth. When all of these data are considered in a comparative context, Proconsul emerges overall as hominoid-like in its enamel and dentine microstructure and as most similar to Pongo but with some features shared with Pan and Homo. Similar data for other Miocene primates will have considerable bearing on how these data are interpreted. These new data on dental microanatomy and on dental development in Proconsul make a further contribution to our understanding of the total morphological picture of this early Miocene primate.

Animals↗
PubMed1998

Possible salmonella osteomyelitis of spine following laser disc decompression.

We report a case of chronic discitis and vertebral osteomyelitis that we believe was caused by Salmonella typhimurium following laser decompression of the L4/5 disc for symptomatic disc protrusion in a 50-year-old Asian man. The infection was successfully treated with intravenous ceftriaxone combined with oral ciprofloxacin. We believe this to be the only report of such a complication following this procedure, which is generally without infective complications.

Discitis↗
PubMed1998

Therapeutic options and cost considerations in the treatment of ischemic heart disease.

Ischemic heart disease is a serious health problem because it causes considerable mortality and morbidity. Given the limited resources for health care, it is important to establish the costs associated with the benefits of its various treatment options. We therefore assessed the costs and benefits of medical treatment versus revascularization in a hypothetical cohort of 100 patients. A spreadsheet model was constructed using published data. The main outputs of this model were health-service costs per year and quality-adjusted survival estimates. In the United Kingdom, costs for treatments of less than 5,000 Pounds/quality-adjusted life-year (QALY) are perceived as highly cost effective, whereas those over 10,000 Pounds/QALY are considered expensive. For patients with intractable symptoms, surgery is highly effective and has benefits on prognosis. In patients with well-controlled symptoms on medical therapy, the benefits of surgery are small and uncertain, and therefore medical therapy is the most cost-effective treatment. Overall, the preferred cost-effective option favored medical treatment.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1998

Isolation of isoproturon-degrading bacteria from treated soil via three different routes.

Three different isolation routes (flask enrichment/flask degradation assay, flask enrichment/microplate degradation assay, MPN assay/microplate degradation assay) were used to obtain pure cultures of bacteria which degraded isoproturon (3-(4-isopropylphenyl)-1,1-dimethylurea) as sole carbon and nitrogen source in a mineral salts medium from a field soil treated with isoproturon in the laboratory. All three isolation routes were successful, but the microplate assay of degradation was more successful than the flask assay. Characterization of 36 isolates indicated that they formed 16 distinct phenotypes (10 Gram-positive phenotypes, six Gram-negative phenotypes) which are likely to represent distinct species. Low concentrations of the degradation product 3-(4- isopropylphenyl)-1-methylurea (IPPMU) were occasionally found in the culture solutions. When provided as the sole source of carbon and nitrogen, the monomethyl degradation product was itself rapidly degraded by several of the isolates. Some isolates were also able to use the demethylated degradation product 3-(4-isopropylphenyl)-urea (IPPU) as sole source of carbon and nitrogen, although there was occasionally an extended lag-phase before rapid degradation commenced. One isolate was particularly active and degraded isoproturon, the monomethyl and demethylated degradation products of isoproturon, and demethylated the related phenylureas diuron and linuron.

Bacteria↗
PubMed1998

An IPSM sponsored intercomparison of surface contamination monitoring test results.

An intercomparison using two popular survey meters was arranged to assess the ability of participants to test surface contamination monitors in compliance with the requirements of the Ionising Radiations Regulations 1985. The instruments were circulated and the data returned were compared with the NRPB values. The major inconsistencies were caused by differences in the interpretation of what constitutes 1 Bq of 90Sr+ 90Y and in the conversion of the emission rate from (129)I plaques into a value of equivalent (125)I activity.

Iodine Radioisotopes↗