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Biomedical subjects

A Walker

Publications and source records attributed to A Walker.

At least 145 records · Page 8Linked to original sources
PubMed1998

Seroprevalence of Helicobacter pylori in a longitudinal study of New Zealanders at ages 11 and 21.

BACKGROUND: Helicobacter pylori seroprevalence increases with age in adult life but spontaneous reversion may occur in childhood and adolescence. AIMS: To determine the seroprevalence of H. pylori in a longitudinal study of New Zealanders at ages 11 and 21. METHODS: Serum from members of the Dunedin Multidisciplinary Health and Development Study (DMHDS) at age 11 (n = 561; 303 males, 258 females) and 21 (n = 785; 413 males, 372 females) was tested for H. pylori antibodies. A large proportion of those tested at age 11 was retested at age 21 (n = 465; 262 males, 203 females). Serological status was examined in terms of gender, socioeconomic status (SES) and self-reported use of antibiotics. RESULTS: The seroprevalence of H. pylori decreased by 38% from 6.6% (37/561) at age 11 to 4.1% (32/785) at age 21. Seroprevalence at age 11 was not associated with gender or SES. For those tested at both ages, the drop in seroprevalence from 6.7% to 4.1% was statistically significant (t = 2.57, p < 0.01, paired t-test) and was much greater in females (71%) than males (12%). Of the 31 seropositive individuals at age 11, 17 (six males, 11 females) seroreverted and self-reported antibiotic use in the year preceeding age 21 was more common in females (eight/11) than males (zero/six). Of the 434 seronegative individuals at age 11, only five (four males, one female) had seroconverted at age 21. CONCLUSIONS: Seroprevalence in the DMHDS declined from age 11 to 21 predominantly in females. The decline involved a greater rate of seroreversion and lower rate of seroconversion in females than males.

Adolescent↗
PubMed1998

Transition from school to adult life for physically disabled young people.

The transition process for young physically disabled people (n = 87) was studied in three districts to determine how it varied between schools, and how it was perceived by the disabled and their carers. The experiences of the young people were compared with guidelines for good practice based on relevant legislation. Results showed that young disabled people experienced a poor handover to adult services if they had no "statement of special educational need" or if they went to further education college. Young people with cerebral palsy or complex multiple problems fared less well than those with spina bifida or juvenile chronic arthritis. There are several deficiencies in the legislation. Physically disabled young people should receive a transition review regardless of whether they have a "statement". The range of severity and type of disorders among the young physically disabled argues for a range of services--the category is too broad to be useful for research, service planning, and provision.

Adolescent↗
PubMed1998

SPECT imaging of feet using uniplanar fad-beam collimators.

BACKGROUND: This study was performed to assess the utility of bone SPECT in the feet using a new commercially available uniplanar fan-beam collimator originally designed for cardiac imaging. METHODS: 18 patients with symptoms or signs of probable skeletal pathology in either the foot or ankle were imaged using a two headed gamma camera fitted with uniplanar fan-beam collimators. All patients were imaged 2.5-4 h after administration of 500-750 MBq 99mTc MDP. If indicated planar dynamic and blood pool images were also obtained. The SPECT acquisition was performed in a 128 x 128 matrix, giving a pixel size of 2.00-2.30 mm depending on the radius of orbit. Images were displayed as transaxial, coronal and sagittal slices and a three dimensional volume rendered image and displayed for reading by three readers blind to the clinical results. Sites of abnormal uptake on the foot SPECT scan were then compared with the site of known or suspected pathology and in 17 patients with planar radiology. RESULTS: The SPECT images produced using the uniplanar fan-beam collimators were of good quality in all patients with all three readers finding localisation easiest on the sagittal and three-dimensional images. In 10 patients abnormalities were found which could explain the patient's symptoms or signs and at the site expected from the patient's clinical history. In 5 patients there were abnormalities on the bone scan in the ipsilateral foot but at a different site, all were interpreted as degenerative disease. 2 patients had contralateral degenerative disease to side suggested by the clinical history and no abnormality in the bones of the foot with symptoms. One patient had bilateral degenerative disease. Planar radiology was normal or unhelpful in 13 of the 17 patients in which it was performed. CONCLUSION: SPECT imaging of feet is possible and provides accurate localisation of abnormal uptake when performed using uniplanar fan-beam collimators with a standard acquisition time of 15 min for a double headed gamma camera.

Journal Article↗
PubMed1997

Germinal center-derived signals act with Bcl-2 to decrease apoptosis and increase clonogenicity of drug-treated human B lymphoma cells.

Bcl-2 suppresses drug-induced apoptosis in vitro, although in many cases, this results only in a delayed onset of cell death. In vivo survival signals from the extracellular environment may also contribute to drug resistance and may act with Bcl-2 to promote long-term cell survival. Ligation of CD40 on B-lymphocytes in germinal centers (GCs) can suppress apoptosis induced by calcium ionophore or anti-IgM in vitro. We asked whether a combination of Bcl-2 expression and the provision of a culture environment that mimicked that of the GC [CD40 ligation and interleukin 4 (IL-4)] could increase the ability of B lymphoma cells to resist drug-induced apoptosis. A Burkitt lymphoma (BL) cell line transfected with either human bcl-2 (BL-bcl-2) or control plasmid (BL-Sv2) was used to examine the effects of Bcl-2 overexpression on the cellular response and long-term survival after treatment with the DNA-alkylating drug chlorambucil (CMB) in the presence or absence of CD40 ligation and IL-4. Administration of 20 microM CMB completely prevented cell proliferation. This was associated with an increase in p53 protein levels within 24 h, without an elevation in p21, Bax, or Mdm2 proteins. Analyses of cell cycle distribution and of cyclin B expression demonstrated that both cell lines arrested at G2/M, where they died. Fifty % of BL-Sv2 cells died within 2 days, whereas 50% cell death was not observed in the BL-bcl-2 cultures until 6 days had passed. Cross-linking of CD40 with a monoclonal antibody elevated Bcl-xL protein levels by 3 h and also provided a delay in CMB-induced death. Ninety-six h after the addition of 20 microM CMB, 78% of the BL-Sv2 cells were apoptotic, whereas ligation of CD40 on BL-Sv2 cells reduced the proportion of apoptotic cells to 38%. Overexpression of Bcl-2 (in BL-bcl-2 cells) reduced apoptosis to 41%. However, when the BL-bcl-2 cells were treated with CMB together with ligation of CD40, apoptosis was reduced further to only 17% at 96 h. The Bcl-2-mediated delay in the execution of CMB-induced apoptosis did not translate significantly to increased clonogenicity. In contrast, the provision of BL-Sv2 cells with an ability to interact with the adhesion molecule vascular cell adhesion molecule-1, CD40 ligation, and IL-4 significantly increased clonogenic survival, and this was improved in BL-bcl-2 cells exposed to these GC-derived signals. These data demonstrate that the kinetics of drug-induced apoptosis can be modulated by Bcl-2 as well as by IL-4, vascular cell adhesion molecule-1, and CD40 ligation, the latter possibly involving the function of Bcl-xL. That these factors appear to act together to enhance proliferative potential after DNA damage has important implications regarding the development of drug resistance in B-cell lymphomas and future strategies for improved chemotherapy.

Antineoplastic Agents, Alkylating↗
PubMed1997

Longitudinal study of cerebral blood flow in Alzheimer's disease using single photon emission tomography.

Ten patients with probable Alzheimer's disease were assessed at baseline and a mean 2 years later using a battery of neuropsychological tests, CT scans and Tc99m-HMPAO SPECT scans. The subjects had declined significantly in their functional indices. Cerebral perfusion measures declined in the parietal lobes, left hemisphere and whole brain, but the overall decline did not reach statistical significance. The decline in brain perfusion did not correlate significantly with the decline in various indices of neuropsychological function, either globally or for specific brain regions. The index of cerebral perfusion correlated significantly with global indices of neuropsychological function at baseline but not at follow-up. No single perfusion index was a significant predictor of clinical progression of dementia.

Adult↗
PubMed1997

Assessing community values in health care: is the 'willingness to pay' method feasible?

In this paper an economics approach to assessing community values in health care priority setting is examined. The approach is based on the concept of 'willingness to pay' (WTP). Eighty two parents were interviewed with regard to three aspects of provision of child health services. For each aspect a choice of two courses of action was presented. Parents were asked which course of action they preferred and what was the maximum amount of money they would be prepared to pay for this rather than their less preferred option. WTP responses are acceptable to the majority of respondents and appear to 'behave' in accordance with a priori expectations. A method of assessing the influence of ability to pay on preferences and WTP is outlined. Preferences and WTP do not appear to have been unduly distorted by ability to pay. Use of WTP data does have the potential to provide health care purchasers and providers with information on intensity as well as direction of the preferences of members of the community.

Child↗
PubMed1997

Persistent patent urachus with allantoic cyst: a case report.

Patent urachus results when there is a persistence of an allantois remnant which normally undergoes atresia during embryological development. It can lead to an abdominal wall defect similar in appearance on ultrasound to an omphalocele. A 34-year-old primigravida presented at 19 weeks' gestation for evaluation of a cystic mass arising at the umbilical cord insertion. The initial impression of the referring physician was an omphalocele. The mass arose from the abdominal wall and the umbilical cord inserted into the membranous covering of the mass, which appeared to be fluid-filled and separate from but contiguous with the urinary bladder. Serial sonography followed the progression of the abdominal wall mass. At term, the patient underwent primary Cesarean section with delivery of a 4494-g male infant. The infant underwent repair and closure of the patent urachus and plastic reconstruction of the abdominal wall. When the urachus remains patent, it can lead to a urinary fistula which mimics the ultrasound appearance of an omphalocele. However, patent urachus is associated with a much lower rate of abnormalities than omphalocele, yielding a better fetal prognosis.

Adult↗
PubMed1997

Is medical treatment for angina the most cost-effective option?

A meta-analysis of the benefits of coronary artery bypass graft (CABG) surgery has been used as the basis of a model for comparing the costs and benefits of surgical and medical treatment of angina pectoris. In order to allow for the results of recent research, the economic model included the addition of aspirin and aspirin plus an HMG-CoA reductase inhibitor (statin) to medical management. The analysis indicates that in unselected patients the cost-effectiveness of CABG vs initial standard medical therapy over 5 years is towards the upper limit of what can be considered a cost-effective treatment both in terms of its effect on mortality (life-years gained) and morbidity (quality adjusted life-years). Addition of a statin to medical therapy reduced mortality and made coronary artery bypass graft surgery an expensive option in terms of improvement of quality of life. In patients with three-vessel disease or left ventricular dysfunction surgery appears fairly cost-effective in comparison with standard medical therapy but becomes relatively expensive when the benefits of aspirin or lipid-lowering therapy are added to medical treatment.

Angina Pectoris↗
PubMed1997

Effects of tetracycline hydrochloride and chlorhexidine gluconate on Candida albicans. An in vitro study.

This study examined the effects of tetracycline hydrochloride (TCN) and chlorhexidine gluconate (CHX) on the growth and viability of Candida albicans. Subcultures of Candida albicans on Sabouraud's agar, were divided into 5 treatment groups: group 1, untreated control; group 2, 0.12% CHX; group 3, 3.0 mg/ml TCN adjusted to pH 4.5; groups 4 and 5, sodium azide free Tris buffer adjusted to pH 4.5 and pH 7.4, respectively. All groups were incubated for 10 days, and sampled and subcultured daily to determine the viability of each group. Additional samples from group 2 (day 4), group 4 (day 7) and all groups at day 10 were selected for SEM and TEM examination. Visual, SEM and TEM results showed that for groups 1, 3, 4, and 5 there was a heavy and constant uniform growth of Candida albicans throughout the period of the study. However, group 2 (CHX), showed decreasing viability and attachment from day 3 to day 10, with SEM and TEM revealing decreased blastospores and profound changes in the ultrastructural morphology, indicating inhibition of normal cell growth and replication. These results show that TCN even when used at high concentrations, in vitro, will allow uninhibited growth of Candida albicans whereas CHX inhibits cell growth and replication.

Adhesiveness↗
PubMed1997

A comparison of two dressings in pressure sore management.

This study compared a polyurethane foam dressing with a hydrocolloid dressing for ease of application and removal, adhesion, conformability, absorbency and wear time. A randomised study was carried out, including 61 patients with stage two or three pressure sores in five centres in the UK. Dressings were applied for up to 30 days and assessments were carried out at each dressing change. The results indicated that both dressings are easy and convenient to apply; absorbency and ease of removal were significantly better with the polyurethane foam dressing than the hydrocolloid dressing; wear times were similar.

Aged↗
PubMed1996

Environment--a new key area for Health of the Nation?

Later this month the government will be consulting on whether the environment should be adopted as a new key area for their Health of the Nation strategy. It is proposing to have five topic areas and to adopt 10-15 environmental targets. This would reaffirm its commitment to linking environmental policy and health policy following publication earlier this year of its environmental health action plan. Critics may respond to the consultation document with suggestions for more far reaching targets--based, for example, on the "Health for All" targets from the World Health Organisation, or those arising out of Agenda 21 from the earth summit in Rio De Janeiro. Whatever the criticism, this move will be a chance to link environmental and health agendas at both national and local level.

Air Pollution↗
PubMed1996

Structural domains of heparan sulphate for specific recognition of the C-terminal heparin-binding domain of human plasma fibronectin (HEPII).

Heparan sulphate (HS) is an abundant polysaccharide component of the pericellular domain and is found in most soft tissues and all adherent cells in culture. It interacts with a wide spectrum of proteins including polypeptide growth factors and glycoproteins of the extracellular matrix. These interactions might influence fundamental cellular activities such as adhesion, growth and migration. HS might therefore represent a highly adaptive mechanism by which cells respond to their environment. The present study shows that the interaction between fibroblast HS, metabolically labelled with [3H]glucosamine, and the C-terminal heparin-binding domain of human plasma fibronectin (HEPII), is determined by distinct regions of the polysaccharide chain. By using a very sensitive affinity-chromatography method and specific polysaccharide scission it was shown that the HEPII-binding regions of HS reside within sulphated domains that are resistant to degradation by heparinase III. In addition, optimal binding was achieved with specific heparinase III-resistant fragments of 14-16 monosaccharides in length. The affinity of HS for HEPII was significantly decreased when the polysaccharide was cleaved with heparinase I. Chondroitin sulphate and dermatan sulphate were poor competitive inhibitors of [3H]HS binding to HEPII whereas unlabelled HS and heparin gave a strong inhibitory activity, with heparin being the most potent inhibitor. These findings suggest that the interaction between HEPII and HS is specific and requires extended sequences of seven to eight N-sulphated disaccharides in which a proportion of the iduronate residues are sulphated at C-2. The results have important implications for the functions of HS in cell adhesion and migration.

Animals↗
PubMed1996

Time course of release of content of single vesicles in bovine chromaffin cells.

The time course of the spontaneous current spikes produced by release of the catecholamine contents of individual vesicles was examined in bovine chromaffin cells using carbon filament electrodes. The rate of spontaneous release was enhanced by adding either LaCl3 (0.01-0.5 mM) or BaCl2 (2 mM) to the extracellular solution. A paucity of events of very short duration was evident from the frequency histograms of the rise and the decay times. In the scatterograms of the rise and of the decay times the regression lines are invariably positive (i.e. the longer the duration of the rise times the longer the duration of the decay times). However, the regression lines never go through the origin but intercept the ordinate (the axis of the decay times) at (+/- SD) 16.1 +/- 6.4 ms (n = 11). On the other hand, the regression lines of paired rise and decay times for the time courses of diffusion are both linear and go through the origin. This relationship holds irrespective of whether the diffusion from an instantaneous point source was assumed to occur in an infinite plane or in an infinite volume. Therefore our experimental findings are incompatible with the model(s) assuming that diffusional broadening determines entirely the time course of current spikes. However, they can be explained, although only partially, by the possible slow speed of the electrode. They thus suggest that in chromaffin cells the duration of exocytosis of individual vesicles is much longer than in synapses.

Animals↗