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Biomedical subjects

P Dawson

Publications and source records attributed to P Dawson.

At least 37 records · Page 2Linked to original sources
PubMed2000

Description of retained abilities in older persons with dementia.

There have been suggestions in the literature that the care of people with dementia must be focused on abilities as opposed to disabilities. However, this approach has not been carefully defined in terms of what constitutes remaining abilities. This article provides a description of the abilities in people with dementia, which is based on a descriptive analysis of data derived from a larger study regarding the psychometric evaluation of an abilities assessment instrument. The sample comprised 112 male veterans with dementia who were living in a long-term care facility. Their mean age was 75 years. Data were collected in the areas of self-care, social, interactional, and interpretive abilities. Abilities were retained in all four areas. Furthermore, abilities were differently affected and varied considerably across subjects, which is consistent with evidence pertaining to cognitive changes in dementia. Our results provide support for an individualized, abilities-focused approach to the care of people with dementia.

Activities of Daily Living↗
PubMed2000

Fibrinolytic actions of intra-arterial angiotensin II and bradykinin in vivo in man.

OBJECTIVES: Angiotensin II and bradykinin are potent endogenous vasoactive peptides which may play a role in the regulation of endogenous fibrinolysis and, thereby, contribute to the beneficial actions of ACE inhibitors. The aims of the study were to determine the acute effect of angiotensin II and bradykinin on the local vascular release of tissue plasminogen activator (t-PA) and its inhibitor, plasminogen activator inhibitor type 1 (PAI-1), and the endothelium-derived haemostatic factor, von Willebrand factor (vWf) from the forearm. METHODS: Blood flow, and plasma haemostatic and fibrinolytic factors, were measured in both forearms of sixteen healthy men: eight subjects received intra-arterial angiotensin II (5, 50 and 500 pmol/min) which was coinfused with sodium nitroprusside (SNP; 0.3, 1.5 and 7.5 microg/min, respectively), and eight received intra-arterial bradykinin at 10-3000 pmol/min. RESULTS: Despite substantial rises in plasma angiotensin II concentrations (P<0.001) which caused pressor effects (P<0.003) at the highest dose, angiotensin II infusion did not affect local plasma t-PA, PAI-1 or vWf concentrations. In contrast, bradykinin caused substantial dose-dependent increases in blood flow and t-PA release (>100 ng/100 ml of tissue/min) in the infused forearm (P<0. 001 for both) without affecting plasma PAI-1 or vWf concentrations. CONCLUSIONS: Despite high local concentrations with breakthrough of significant systemic effects, angiotensin II did not affect acute endothelial cell t-PA, PAI-1 or vWf release in healthy men. In contrast, bradykinin is a potent vasodilator and selective stimulus for acute local t-PA release. This may, at least in part, explain the fibrinolytic actions of ACE inhibitors in heart failure and ischaemic heart disease.

Adult↗
PubMed2000

Chemical etching of optical fibre tips--experiment and model.

The formation of chemically etched fibre tips for use in optical scanning probe microscopy is addressed. For tips formed at a cleaved fibre end in the bulk of a buffered HF acid solution the morphological features (tip height, cone angle) are found to depend strongly on the temperature and etchant composition. The tip formation process is analysed and explained in terms of a simple model in which the only pertinent physical parameters are the fibre core diameter and etch rates of the fibre core and cladding. The etch rates are determined in separate experiments as a function of temperature (in the range 24-50 degrees C) for etchant solutions of de-ionised water: 50% HF acid: 40% NH4F in the volume ratio 1:1:X for X = 2, 4 and 6, and used in the model to yield a correct description of the experimental tip cone angles. The model is successfully extended to the intriguing case of negative tip formation which initiates in a normal, positive tip structure. By contrast, tip formation in the meniscus region of a bare fibre/etchant/organic solvent system is found to be independent of etchant composition and temperature.

Journal Article↗
PubMed2000

Effects of an abilities-focused program of morning care on residents who have dementia and on caregivers.

OBJECTIVE: To conduct a controlled investigation to examine the effects of an abilities-focused program of morning care on the interaction behaviors and functioning of residents with dementia and on caregivers' interaction behaviors and perceptions of caregiving. DESIGN: A quasi-experimental, repeated measures design. SETTING: The study was conducted on four, nursing-home-level cognitive supports units in a geriatric care center. One of the units was randomly selected as the experimental unit; the other three served as controls. PARTICIPANTS: The final sample consisted of 40 residents (20 each in the experimental and three control groups) and 44 caregivers (16 on the experimental unit and 28 on the three control units). INTERVENTION: An educational program on delivering abilities-focused morning care, designed by the authors, was provided to caregivers on the experimental unit. MEASUREMENTS: Measures were taken at baseline and at 3 and 6 months postintervention with regard to residents' interaction behaviors, level of agitation, and level of function and to caregivers' interaction behaviors, perceived ease of caregiving, and level of stress. RESULTS: Repeated measures analysis of variance (RM-ANOVA) was used to compare the experimental and control groups in regard to changes in the outcomes over time. Results indicated that the abilities-focused program had statistically significant effects on (a) residents' personal attending and calm/functional behaviors, level of agitation, and levels of overall and social function, and (b) caregivers' verbal relevance and personal attending, relaxed, and social/flexible behaviors. CONCLUSIONS: The evidence suggests that both residents and caregivers benefit from morning care that is oriented toward the abilities of people with dementia.

Aged↗
PubMed2000

Current practice patterns in the treatment of Charcot foot.

Treatment of Charcot foot osteoarthropathy has emerged as a major component of the American Orthopaedic Foot and Ankle Society (AOFAS) Diabetes 2000 Initiative. A two-part survey described treatment patterns and current footwear use of patients with Charcot osteoarthropathy of the foot and ankle. In the first part, 94 consecutive patients with a history of Charcot foot and ankle presenting for care were questioned on their foot-specific treatment and current footwear use. A history of diabetic foot ulcer was given by 39 (41%) patients, and an infection had been present in a foot of 20 (21%) patients. The initial treatment of the Charcot foot and ankle had been a total contact cast in 46 (49%) patients, and a pre-fabricated walking boot in 19 (20%). Charcot related surgery had consisted of 76 procedures in 46 (49%) patients. Sixty-three (67%) patients were currently using accommodative footwear (depth-inlay shoes in 46 [49%], custom shoes in 10 [11%], and CROW in 7 [7%] patients), and 72 (77%) were currently using custom accommodative foot orthoses. The second part of this study consisted of a questionnaire completed by 37 orthopaedic surgeons (members of AOFAS) interested in forming a Charcot Study Group. They treated an average of 11.8 patients having Charcot foot or ankle per month. Thirty (81%) used the Semmes-Weinstein 5.07 monofilament as a screening tool for peripheral neuropathy. For treatment of Eichenholtz Stage I, 29 (78%) used a total contact cast and 15 (41%) allowed weightbearing; for Stage II, 30 (81%) physicians used a total contact cast and 18 (49%) allowed weightbearing. Although the literature contains uniform recommendations for immobilization and non-weightbearing as treatment for the initial phases of Charcot arthropathy, the results of this benchmarking study reveal that currenl treatment is varied.

Adult↗
PubMed2000

Development of a lyophilization formulation that preserves the biological activity of the platelet-inducing cytokine interleukin-11 at low concentrations.

Recombinant human interleukin-11 (rhIL-11) is a licensed biological therapeutic product in at least one country and is used to combat thrombocytopenia during chemotherapeutic regimens, as well as undergoing clinical trials for a range of other disorders. Following attempts to lyophilize IL-11 at low concentrations, it was clear that a significant loss of recoverable biological activity occurred. Investigation of a variety of factors, including the type of container in which the rhIL-11 was lyophilized, revealed that surface adsorption to glass was a major factor resulting in loss of activity of rhIL-11 in solution (> 40% reduction after 3 h at room temperature), in addition to losses of activity post-lyophilization. To overcome this problem, different formulations containing combinations of human serum albumin (HSA), trehalose and Tween-20 have been investigated. Two formulations were successful in entirely preserving the biological activity of rhIL-11 through lyophilization and subsequent reconstitution (potency estimates of formulated relative to original material being > or =0.97). Accelerated degradation studies, performed at intervals over a six-month period, demonstrated the stability of freeze-dried rhIL-11 using these formulations (predicted annual reduction in potency after storage at -20 degrees C < or =1.4%). In conclusion, we have developed a working combination of excipients (0.5% HSA, 0.1% trehalose and 0.02% Tween-20 in potassium phosphate buffer (pH 7.4)) to formulate a stable rhIL-11 freeze-dried product in glass containers, with no loss in potency. These findings should facilitate development of low dose rhIL-11 products and be an indicator of caution to those using this and other material with similar physical properties, without taking appropriate precautions to avoid losses through adsorption.

Adsorption↗
PubMed2000

Gadolinium-DTPA as X-ray contrast medium in clinical studies.

The aim of this study was to investigate the contrast effects of gadolinium (Gd) in patients undergoing digital subtraction angiography (DSA), intravenous urography (IVU) and CT. 15 patients attending for coeliac axis DSA (n = 5), abdominal CT (n = 5) and IVU (n = 5) were injected with 0.3 mmol kg-1 Gd-DTPA, the maximum approved dose. For DSA and IVU, images were categorized as being of diagnostic or non-diagnostic quality. For CT, enhancement was measured in Hounsfield Units (HU). On CT, enhancement with Gd was reproducible in all cases; average peak aortic enhancement was 75 HU but duration was short. On IVU, four of five studies yielded positive pyelograms but all nephrograms were relatively poor. On DSA, all five patients had diagnostic arteriograms and four of five indirect portograms were of diagnostic quality. In all 15 cases, enhancement was weaker than that achieved with routine dosage of iodinated agents. In conclusion, Gd chelates may be clinically useful in X-ray studies under certain circumstances on patients with contraindications to iodinated agents. Higher doses than currently approved would be potentially useful.

Adult↗
PubMed2000

Local and systemic effects of intra-arterial desmopressin in healthy volunteers and patients with type 3 von Willebrand disease. Role of interleukin-6.

Intra-arterial desmopressin caused dose and time dependent increases (p <0.001 for all) in forearm blood flow (all doses) and plasma tissue plasminogen activator (t-PA) concentrations (desmopressin > or = 70 ng/min). Although plasma t-PA concentrations rose in both forearms, there was a modest local release of t-PA in the infused forearm (14 ng/100 mL of tissue/min, p <0.05). At desmopressin doses > or = 300 ng/min, plasma von Willebrand factor (vWf) and Factor VIII:C concentrations rose in both forearms (p <0.001) and correlated with the rise in interleukin-6 concentrations (r = 0.92, p <0.001: r = 0.85, p = 0.002 respectively). Neither desmopressin nor substance P caused t-PA, vWf or Factor VIII:C release in the patients, although desmopressin increased plasma interleukin-6 concentrations as in healthy volunteers. We conclude that desmopressin releases t-PA, vWf and Factor VIII:C predominantly via systemic mechanisms, possibly mediated by cytokine release. Patients with type 3 vWD appear to have a generalised failure to release t-PA acutely despite a normal interleukin-6 response to desmopressin infusion.

Adult↗
PubMed1999

Prevalence of back, neck and shoulder problems in the inner city: implications for the provision of physiotherapy services in primary healthcare.

BACKGROUND AND PURPOSE: More general practitioners are offering physiotherapy services within primary healthcare; however, this provision may result in increased demand. Resource allocation, based on previous patterns of consultation for musculoskeletal conditions, may be inadequate since the need for treatment in the community may not have been met in the past. Therefore the aim of this study was to determine the prevalence of back, neck and shoulder problems that had restricted normal activity for more than one week during the last year and which health professionals (if any) patients had consulted about their symptoms. METHOD: A postal survey of 2400 adult patients selected at random from four general practices in Newcastle upon Tyne (600 from each practice). RESULTS: A total of 1546 questionnaires were returned, a 64% response rate. Overall, 40% of respondants reported having at least one back, neck and/or shoulder problem. Back problems were most common (30%), followed by those with neck (21%) and shoulder (20%) problems. Approximately one-third of those with problems consulted no one, a further third consulted a general practitioner and only one in six consulted a physiotherapist. CONCLUSIONS: There is a high prevalence of substantial back, neck and shoulder problems in the community and thus a wider provision of physiotherapy services within primary healthcare may be required to manage the considerable levels of potentially unmet need.

Adolescent↗
PubMed1999

Early presentation of type 2 diabetes mellitus in young New Zealand Maori.

For 51 (5%) of the 1052 Maori patients registered with the Northland New Zealand (NZ) Diabetes Service, an initial diagnosis of diabetes was made before they had reached 30 years of age. We reviewed epidemiological and clinical data of this patient group. A total of 28 patients (55%) have type 2 diabetes, 18 (35%) have type 1 diabetes and for five patients, we were unable to determine the type of diabetes. The majority have positive family histories of diabetes (83%). The average age at diagnosis was 12.4 years for type 1 and 19.1 years for type 2 diabetes. Mean duration of diabetes and mean current HbA1c were not statistically different between the two groups, yet microalbuminuria or nephropathy was present in 62% of type 2 patients, but only 18% of the type 1 group. These statistics show that a significant number of Northland NZ Maori develop type 2 diabetes at an earlier age than expected and have a high incidence of renal complications. These findings contrast with previous New Zealand studies on the incidence of diabetes in young Maori, but are similar to those of recent overseas studies of ethnic groups with a high incidence of diabetes.

Adolescent↗
PubMed1999

Functional renal perfusion imaging with colour mapping: is it a useful adjunct to spiral CT of in the assessment of abdominal aortic aneurysm (AAA)?

AIM: To ensure optimal timing with pre-operative spiral CT for abdominal aortic aneurysms (AAA), an initial 'timing' single level CT is commonly performed with a small bolus of contrast. This can be exploited to obtain adjunct functional information on renal perfusion. We have investigated the potential of this to measure renal perfusion, to produce colour renal perfusion maps and to predict surgical outcome in infrarenal aortic aneurysm assessment. METHODS: We studied 21 patients being assessed for repair of infrarenal AAA. Prior to the spiral CT, a single level through the renal hili and aorta was scanned after the intravenous injection of 25 ml of contrast given at 10 ml/s. Ten 1 s duration scans were performed from 8 to 30 s after injection. Optimal timing for CT angiography can then be determined. Time-density curves were then drawn for both kidneys and aorta using regions of interest (ROIs) or pixel-by-pixel analysis. Renal cortical perfusion was measured using both ROI analysis and pseudocolour perfusion images. Following previous work, perfusion was calculated as the peak upslope of the tissue time density curve divided by peak aortic enhancement. RESULTS: Cortical mean perfusion averaged 2.48 ml/min per ml (range 0.8-3.7 ml/min per ml n = 34) and the values obtained agreed with literature expectations. Follow up in the 10 patients proceeding to AAA repair suggest low mean perfusion values and predict a raised postoperative creatinine (P < 0.05) CONCLUSIONS: Additional functional data and imaging can be obtained from the initial timing scan of a CT study, without requiring a dedicated study.

Aged↗
PubMed1999

Imaging of tumour therapy responses by dynamic CT.

The objective of this study was to investigate whether functional CT with Patlak analysis could be used to demonstrate acute changes associated with radiotherapy. Patlak analysis yields fractional vascular volume and contrast clearance per unit volume (a measure of permeability). Four tumour types (prostate, bronchus, breast and cervix) were studied pre-radiotherapy and at 1-2 weeks and 6-12 weeks post-therapy. Significant rises in fractional vascular volume and contrast clearance were shown at 1-2 weeks. These indices were still significantly elevated at 6-12 weeks post-therapy. In the prostates perfusion values were also elevated reflecting a hyperemic response to radiotherapy. Dynamic CT with Patlak analysis can be used to measure important pathophysiological indices which may prove useful in assessing response to therapy of tumours.

Breast Neoplasms↗
PubMed1999

The meaning and significance of the equilibrium phase in enhanced computed tomography of the liver.

The "equilibrium phase" (EP) in liver contrast enhancement in CT is generally held to be a potential pitfall by way of loss of intrinsic lesion conspicuity. Unfortunately, the definitions extant in the literature are not firmly rooted in a pharmacokinetic basis. Such a basis is developed in this article and a method is described for estimating the time of onset of the EP. It is shown that this may be, effectively, as early as 120 s or so after the beginning of a typical infusion of contrast agent. This means that incremental scanning protocols are likely to result in later slices being acquired in the EP. It is further shown that the pharmacokinetic model does predict a danger of loss of lesion conspicuity in EP scanning. Fortunately, rapid helical/spiral scanning makes it a danger that is easily avoided.

Contrast Media↗