Biomedical subjects

S M Dunn

Publications and source records attributed to S M Dunn.

At least 19 recordsLinked to original sources

PubMed2006

Relationship between stress and relapse in multiple sclerosis: Part I. Important features.

OBJECTIVE: The aim of this two-year prospective study was to examine the relationship between multiple aspects of life-event stress and relapse in multiple sclerosis (MS) patients. BACKGROUND: Few studies have defined the critical features of this life-event stress; for example, stressor duration, frequency, severity, disease-dependency, valency, or stressor constructs, such as the propensity to cause emotional distress/threat or the frustration of life goals. METHODS: 101 consecutive participants with MS were recruited from two MS clinics in Sydney, Australia. Stressful life events were assessed at study-entry and at three-monthly intervals for two years. Patient-reported relapses were recorded and corroborated by neurologists or evaluated against accepted relapse criteria. RESULTS: Acute events, but not chronic difficulties (CDs), predicted relapse occurrence: acute stressor frequency counts predicted greater relapse risk, along with low disability score (EDSS) and being male. We also confirmed the bi-directional stress-illness hypothesis: stressors predicted relapse, and relapse separately predicted stressors. CONCLUSIONS: Life-event stress impacts to a small degree on MS relapse. The number and not the severity of acute stressors are most important; chronic stressors do not predict later relapse. Males and those with early stage disease are also at greater risk of relapse. MS patients should be encouraged to reduce acute stressors during times of high stress, and feel reassured that disease-related chronic stressors do not increase their relapse risk.

Acute Disease↗

PubMed2006

Relationship between stress and relapse in multiple sclerosis: Part II. Direct and indirect relationships.

OBJECTIVE: The aim of this two-year prospective study was to determine which factors were: (i) directly related and/or (ii) indirectly related to multiple sclerosis (MS) relapse. These factors included life-event stressors, disease, demographic, psychosocial and lifestyle factors. BACKGROUND: Relatively little attention has been paid to the role of non-clinical relapse predictors (other than stressful life-events) in MS, or factors that indirectly impact on the stress-relapse relationship. METHODS: A total of 101 consecutive participants with MS were recruited from two MS clinics in Sydney, Australia. Stressful life-events, depression, anxiety and fatigue were assessed at study-entry and at three-monthly intervals for two years. Disease, demographic, psychosocial and lifestyle factors were assessed at baseline. Patient-reported relapses were recorded and corroborated by neurologists or evaluated against accepted relapse criteria. RESULTS: MS relapse was predicted by acute stressor frequency counts, coping responses that utilized social support, and being born in Australia, but not by chronic stressors, disease, demographic, psychosocial or lifestyle factors. No factors were found to indirectly impact on the stress relapse relationship. CONCLUSIONS: The number rather than severity of stressors was most important in relation to MS relapse risk, along with coping responses that utilized social support, suggesting that MS patients should avoid situations that are likely to generate multiple stressors or which provide few avenues for social support.

Adult↗

PubMed2005

Isotopic characterisation of the historical lead deposition record at Glensaugh, an organic-rich, upland catchment in rural N.E. Scotland.

As part of a wider investigation of the biogeochemistry and fate of Pb deposited from the atmosphere at Glensaugh, a rural upland catchment in N.E. Scotland, the concentration and isotopic composition of Pb were determined in four thinly sectioned monolith cores (25 cm) of peat collected at altitudes of 426--434 m from different faces of Thorter Hill and in a series of 21 10-cm unsectioned cores of peat and organic-rich soil along a transect from near the top (434 m) to the bottom (224 m) of the catchment. Depth profiles of Pb concentration and (206)Pb/(207)Pb ratio were similar for the longer cores. Subsurface Pb maxima (238--489 mg kg(-1)) typically occurred below (206)Pb/(207)Pb minima (1.123-1.134). One core was (210)Pb-dated and had a fairly constant (206)Pb/(207)Pb value of 1.170 from mid-19th century to ca. 1930, followed by a decline (attributable to the increasing influence of Australian Pb of much lower (206)Pb/(207)Pb ratio) to 1.134 by the early 1990s, and then a rapid increase to 1.160 by 2002, after the phased withdrawal of leaded petrol. The fluxes of Pb increased from 15 mg m(-2) year(-1) in the late 19th century to a peak of 60 mg m(-2) year(-1) ca. 1960, before declining steadily to 3.6 mg m(-2) year(-1) by the beginning of the 21st century. Some 40% of the anthropogenic Pb in the core had been deposited prior to 1900. The mean anthropogenic Pb inventory of the four longer cores was 7.4+/-1.5 g m(-2), of which approximately 70% occurred in the top 10 cm, in good agreement with the inventories of the shorter cores collected above 400 m. These inventories are higher than those of the industrial central belt of Scotland, probably because of enhanced deposition at altitude. This is consistent with the derived average (210)Pb flux of 198+/-11 Bq m(-2) year(-1), which is twice that of typical UK (210)Pb deposition and the rainfall for the site. The past deposition of Pb at Glensaugh, including that from sources (e.g., smelting, coal combustion) other than leaded petrol, has clearly been considerable. Even since the introduction of leaded petrol ca. 1930, car-exhaust emissions may have accounted for no more than 35% of the Pb deposited.

Journal Article↗

PubMed2005

A review of stress-relapse interactions in multiple sclerosis: important features and stress-mediating and -moderating variables.

Studies do not provide a consensus opinion of the relationship between stress and relapse in relapsing-remitting multiple sclerosis (RRMS). Few studies have defined the critical features of these stressful situations, or examined the role of stress-mediating and -moderating variables. Available evidence indicates that the relationship between life stress and relapse is complex, and is likely to depend on factors such as stressor chronicity, frequency, severity and type, and individual patient characteristics such as depression, health locus of control and coping strategy use. Little is known about how these factors, individually or in combination, are related to MS disease activity. Viral infections are also likely to precipitate relapse in MS, and significant life-stress may further enhance this relationship. The nature and strength of these interrelationships have strong clinical implications. MS patients are particularly vulnerable to a deteriorating cycle of stressful life events, illness episodes and disability. Timely multidisciplinary care interventions aimed at both minimizing psychological distress and physical symptoms may halt this downward reciprocal cycle. Little is known of the pathogenesis of these putative stress-induced changes in disease activity, and almost all stressor studies suffer from some biases or limitations.

Anxiety↗

PubMed2005

Modelling nitrate losses from agricultural activities on a national scale.

The Nitrogen Risk Assessment Model for Scotland (NIRAMS) has been developed as a screening tool for prediction of streamwater N concentrations draining from agricultural land in Scotland. The objective of the model is to be able to predict N concentrations for ungauged catchments, to fill gaps in monitoring data and provide guidance in relation to policy development. The model uses national land use, soils and meteorology data sets and has been developed within an ArcView GIS user interface. The model includes modules to calculate N inputs to the land, residual N remaining at the end of the growing season, weekly time-series of leached N and transport of N at the catchment scale. The N leaching and transport are. controlled by hydrological modules, including a national water balance model and a catchment scale transport model. Preliminary testing of NIRAMS has been carried out on eight Scottish catchments, diverse in terms of geographic location as well as land use. The model is capable of predicting the correct mean level of stream N concentrations, as well as the basic characteristics of seasonal variation. As such the model can be of value for providing estimates of N concentrations in ungauged areas.

Agriculture↗

PubMed2003

Psychological responses of patients receiving a diagnosis of cancer.

BACKGROUND: Current recommendations on how to break bad news are primarily based on expert opinion. Little is known about the association between communication practices and patients' psychological response. PATIENTS AND METHODS: One-hundred and thirty-one patients with newly diagnosed melanoma were surveyed 4 months after the initial consultation at the Sydney Melanoma Unit regarding their communication experiences and their satisfaction with these experiences. They completed the Hospital Anxiety and Depression Scale (HADS) at this time, and 4 and 13 months later. RESULTS: Both patients' satisfaction with communication and their psychological morbidity were found to be associated with particular communication practices. Practices linked to lower anxiety included preparing the patient for a possible diagnosis of cancer; having the people wanted by the patient present to hear the diagnosis; giving the patient as much information about the diagnosis as desired; providing written information; presenting the information clearly; discussing the patient's questions the same day; talking about the patient's feelings; and being reassuring. Practices linked with lower levels of depression included using the word 'cancer'; discussing the severity of the situation, life expectancy and how the cancer might affect other aspects of life; and encouraging the patient to be involved in treatment decisions. CONCLUSIONS: This study provided preliminary evidence that communication strategies recommended in the literature produce positive patient outcomes. Further studies are needed which document actual communication.

Adaptation, Psychological↗

PubMed2003

Feasibility of local CT of dental tissues.

OBJECTIVES: To prove the feasibility of a local CT system as a method of CT suitable for use in dentistry. METHODS: Using an experimental set-up consisting of an X-ray source, a turntable and a charge-coupled device (CCD) detector connected to a PC, CT scans were made of a single molar and a dry mandible. Slices were reconstructed using filtered backprojection. An experimental comparison was made between a full CT geometry and a local CT geometry. RESULTS: Horizontal and vertical slices through the mandible were obtained showing the internal structure of a molar and the surrounding bone. The slices show good contrast and details. A computer experiment gave visual evidence that slices obtained by local CT are not substantially different from slices obtained from a full CT set-up with respect to resolution. CONCLUSIONS: Based on the results obtained so far, local CT of dental structures appears to be a promising diagnostic instrument.

Feasibility Studies↗

PubMed2003

Modelling the influence of irrigation abstractions on Scotland's water resources.

Legislation to control abstraction of water in Scotland is limited and for purposes such as irrigation there are no restrictions in place over most of the country. This situation is set to change with implementation of the European Water Framework Directive. As a first step towards the development of appropriate policy for irrigation control there is a need to assess the current scale of irrigation practices in Scotland. This paper presents a modelling approach that has been used to quantify spatially the volume of water abstractions across the country for irrigation of potato crops under typical climatic conditions. A water balance model was developed to calculate soil moisture deficits and identify the potential need for irrigation. The results were then combined with spatial data on potato cropping and integrated to the sub-catchment scale to identify the river systems most at risk from over-abstraction. The results highlight that the areas that have greatest need for irrigation of potatoes are all concentrated in the central east-coast area of Scotland. The difference between irrigation demand in wet and dry years is very significant, although spatial patterns of the distribution are similar.

Agriculture↗

PubMed2001

Promoting patient participation and shortening cancer consultations: a randomised trial.

Patient participation in medical consultations has been demonstrated to benefit their subsequent psychological well being. Question asking is one way in which patients can be active. We investigated 2 means of promoting cancer patient question asking. One was the provision of a question prompt sheet to patients prior to their initial consultation with their oncologist. The second was the active endorsement and systematic review of the question prompt sheet by their oncologist. 318 patients with heterogeneous cancers, seeing one of 5 medical and 4 radiation oncologists for the first time, were randomised to either receive or not receive a question prompt sheet. Doctors were randomised to either proactively address or passively respond to the question prompt sheet in the subsequent consultation. Anxiety was assessed prior to the consultation. Consultations were audiotaped and content analysed. Anxiety was assessed again immediately following the consultation. Within the next 10 days patients completed questionnaires assessing information needs, anxiety and satisfaction and were given a structured telephone interview assessing information recall. Patients provided with a question prompt sheet asked more questions about prognosis compared with controls and oncologists gave significantly more prognostic information to these patients. Provision of the question prompt sheet prolonged consultations and increased patient anxiety; however, when oncologists specifically addressed the prompt sheet, anxiety levels were significantly reduced, consultation duration was decreased and recall was significantly improved. A patient question prompt sheet, used proactively by the doctor, is a powerful addition to the oncology consultation.

Adolescent↗

PubMed2001

Randomized clinical trials in oncology: understanding and attitudes predict willingness to participate.

PURPOSE: To explore the association at different time points in the trajectory of breast cancer care, between anxiety, knowledge, and attitudes, on women's willingness to participate in randomized clinical trials. MATERIALS AND METHODS: A cross-sectional survey was undertaken among women attending a breast clinic for screening mammography or diagnostic assessment plus women with newly diagnosed breast cancer to assess attitudes toward and willingness to participate in randomized clinical trials of breast cancer treatment. RESULTS: Five hundred forty-five women completed questionnaires assessing knowledge of and attitudes toward randomized clinical trials. The mean age of respondents was 48.9 years (SD, 11.3 years). Thirty-three percent of women would consider participating in a clinical trial if they had breast cancer. Women with breast cancer (31%) were significantly more likely to decline to participate than women attending for screening mammography (15%) or diagnostic assessment (15%, P =.0002). Women who might consider participating in a randomized clinical trial were more knowledgeable about randomized trials (mean difference, 0.7; 95% confidence interval [CI], 0.2 to 1.2; P =.003). In a multivariate analysis, women who would consider participating in a randomized trial were younger (odds ratio [OR], 0.96; 95% CI, 0.93 to 0.99), more likely to want an active role in decision-making (OR, 3.2; 95% CI, 1.3 to 7.6), and reported a greater impact from the positive aspects of clinical trials (OR, 2.2; 95% CI, 1.3 to 3.8) and less impact from the negative aspects of clinical trials (OR, 2.2; 95% CI, 1.3 to 3.2). CONCLUSION: These findings suggest that women who have a better understanding of issues about clinical trials have more favorable attitudes toward randomized trials and are more willing to consider participation in a clinical trial.

Adolescent↗

PubMed2001

Direct inhibition of voltage-dependent Ca(2+) fluxes by ethanol and higher alcohols in rabbit T-tubule membranes.

The effects of ethanol and higher alcohols on 45Ca(2+) fluxes, mediated by voltage-dependent Ca(2+) channels (VDCCs), were investigated in inside-out transverse (T)-tubule membrane vesicles from rabbit skeletal muscle. 45Ca(2+) effluxes were induced by membrane potentials generated via establishing K(+) gradients across the vesicles, and were significantly inhibited by the inorganic Ca(2+) channel blocker La(3+) (1 mM) and the Ca(2+) channel antagonist nifedipine (1-10 microM). Ethanol, in the concentration range of 100-400 mM, caused a significant suppression of depolarization-induced 45Ca(2+) fluxes. Ethanol also functionally modulated the effect of nifedipine (1-10 microM) and the Ca(2+) channel agonist Bay K 8644 (1 microM) on Ca(2+) effluxes. Pretreatment with pertussis toxin (5 microg/ml) or phorbol 12-myrstate 13-acetate (PMA, 50 nM) did not affect the ethanol inhibition of 45Ca(2+) fluxes. Further experiments with alcohols revealed that butanol, hexanol, octanol and decanol also significantly inhibited 45Ca(2+) effluxes. However, undecanol and dodecanol did not cause any significant change on 45Ca(2+) fluxes, indicating that the effects of alcohols on 45Ca(2+) effluxes exhibit a cut-off phenomenon. In radioligand binding studies, it was found that at the concentrations used in flux studies, alcohols did not alter the characteristics of the specific binding of [3H]PN 200-110 to T-tubule membranes. Results indicate that ethanol directly inhibits the function of voltage-dependent Ca(2+) channels without modulating the specific binding of Ca(2+) channel ligands of the dihydropyridine class, and that this inhibition is independent of intracellular Ca(2+) levels.

Alcohols↗

PubMed2001

The role of psychosocial factors in the development of breast carcinoma: Part I. The cancer prone personality.

BACKGROUND: The authors conducted the current study to determine whether personality predisposes some individuals to develop cancer. METHODS: The current study examined the role of personality variables in 2224 older women recalled for assessment after routine mammography in a breast screening program. Using a semiprospective design, subjects completed self-report measures of defense style, locus of control, emotional expression and control, self-esteem, trait anxiety, and state anxiety and depression while waiting for medical examination. Multivariate analysis of variance was used to control for known risk factor variables and to examine differences between 3 control groups (normal tissue controls, benign/cystic controls not requiring biopsy, and benign biopsy controls) and 298 breast carcinoma subjects. RESULTS: No differences were detected between breast carcinoma subjects and controls based on measures of mature, immature, and neurotic defense style; locus of control of behavior; emotional expression-in, emotional expression-out, and emotional control; self-esteem; anxiety; or depression. CONCLUSIONS: The results of the current study found no evidence to support an independent association between these personality measures and the development of breast carcinoma. [See accompanying article on pages 686-97, this issue.]

Aged↗

PubMed2001

The role of psychosocial factors in the development of breast carcinoma: Part II. Life event stressors, social support, defense style, and emotional control and their interactions.

BACKGROUND: The evidence supporting an association between life event stress and breast carcinoma development is inconsistent. METHODS: Five hundred fourteen women requiring biopsy after routine mammographic breast screening were interviewed using the Brown and Harris Life Event and Difficulties Schedule. Other psychosocial variables assessed included social support, emotional control, and defense style. Biopsy results identified 239 women with breast carcinoma and 275 women with benign breast disease. Multiple logistic regression analysis was used to distinguish between breast carcinoma subjects and benign breast disease controls based on these psychosocial variables and their interactions. RESULTS: The findings of the current study revealed a significant interaction between highly threatening life stressors and social support. Women experiencing a stressor objectively rated as highly threatening and who were without intimate emotional social support had a ninefold increase in risk of developing breast carcinoma. CONCLUSIONS: Although there was no evidence of an independent association between life event stress and breast carcinoma, the findings of the current study provided strong evidence that social support interacts with highly threatening life stressors to increase the risk of breast carcinoma significantly. [See also accompanying article on pages 679-85, this issue.]

Adaptation, Psychological↗

PubMed2001

The impact of variable snow pack accumulation on a major Scottish water resource.

In regions such as northern Scotland, where winter temperatures are such that the occurrence of snow is borderline under the present climate, potential changes affecting precipitation and temperature regimes may have a disproportionately large impact on snow processes and hydrological behaviour. The physical characteristics of mountainous areas in Scotland mean that the spatial variability of snowpack accumulation is high, as well as the temporal variability caused by the climate. There have been few modelling studies aimed at assessing the significance of snow resources in these areas and none that have adopted a spatially distributed approach. This paper describes the approach taken in applying a new distributed model to a headwater catchment in the Cairngorm Mountains. The results demonstrate the importance of wind on re-distributing snow to create deep accumulations in small sheltered pockets. These accumulations are shown to be important in sustaining baseflows in the rivers, long after snow has melted from the rest of the catchment. The model has also produced a first set of maps showing how predicted snow depths vary across the catchment through the winter.

Journal Article↗

PubMed2001

Assessing the effects of land use on temporal change in well water quality in a designated nitrate vulnerable zone.

The nitrate concentration in discharge from the Balmalcolm borehole in Fife, Scotland, has steadily increased from 4.5 mg l(-1) NO3-N in the early 1970s to 11.0 mg l(-1) NO3-N in 1998. Consequently the catchment of the borehole, covering an area of 400 ha has recently been designated a Nitrate Vulnerable Zone under the EC Nitrate Directive [Commission of European Communities L375, (1991) 1]. The sandstone aquifer that supplies the borehole is recharged by water draining from land that is intensively cropped to green vegetables. There is, therefore, a need to identify appropriate land management techniques that will help to abate the nitrate losses from the land and to estimate the length of time that it is likely to take before the abatement is observed as a decrease in well-water concentrations. Estimates of nitrate leaching for the range of crops that have been grown in the catchment over the last 30 years have been made using a balance sheet approach, modified to allow for estimates of denitrification and in-field composting of vegetable crop residues. Integration over the whole catchment using a GIS approach, indicates a steady-state well water [NO3--N] of 23 mg l(-1)--a situation that has not yet been reached. Prediction of the time course of change in well water quality from 1970 (when intensification began) has been made by calculating the travel time from different parts of the catchment both in the saturated and unsaturated zones. The results show good agreement between the measurements and simulation. Well water [NO3-N] under potential future management scenarios have also been investigated using the same approach. The greatest reduction in steady-state concentration, to 9 mg l(-1), is achieved for the scenario of extensification to spring cereals with moderately fertilised grassland. However, the temporal simulations suggest that it would take approximately 100 years before 80% of this change is observed in the well-water, starting from a concentration of 23 mg l(-1) .

Agriculture↗

PubMed2001

An analysis of perceptual errors in reading mammograms using quasi-local spatial frequency spectra.

In this pilot study the authors examined areas on a mammogram that attracted the visual attention of experienced mammographers and mammography fellows, as well as areas that were reported to contain a malignant lesion, and, based on their spatial frequency spectrum, they characterized these areas by the type of decision outcome that they yielded: true-positives (TP), false-positives (FP), true-negatives (TN), and false-negatives (FN). Five 2-view (craniocaudal and medial-lateral oblique) mammogram cases were examined by 8 experienced observers, and the eye position of the observers was tracked. The observers were asked to report the location and nature of any malignant lesions present in the case. The authors analyzed each area in which either the observer made a decision or in which the observer had prolonged (>1,000 ms) visual dwell using wavelet packets, and characterized these areas in terms of the energy contents of each spatial frequency band. It was shown that each decision outcome is characterized by a specific profile in the spatial frequency domain, and that these profiles are significantly different from one another. As a consequence of these differences, the profiles can be used to determine which type of decision a given observer will make when examining the area. Computer-assisted perception correctly predicted up to 64% of the TPs made by the observers, 77% of the FPs, and 70% of the TNs.

Breast Neoplasms↗

PubMed2001

Comparison of wire reinforced tubes with warmed standard tubes to facilitate fiberoptic intubation.

STUDY OBJECTIVE: To compare the ease of insertion of a warmed standard tracheal tube to that of a wire reinforced tracheal tube when placed over a flexible fiberoptic bronchoscope. DESIGN: Randomized controlled trial. SETTING: Tertiary care hospital. PATIENTS: 50 patients undergoing elective general anesthesia. INTERVENTIONS: Patients' tracheas were intubated with a flexible fiberoptic bronchoscope and had either a standard or wire-reinforced tracheal tube inserted. If resistance was met, the tube was withdrawn, rotated, and readvanced. This was repeated two times. If unsuccessful, the flexible fiberoptic bronchoscope was removed, and intubation was attempted with the other type of tracheal tube. MEASUREMENTS: The ability to advance the tracheal tube was determined. MAIN RESULTS: There were no demographic differences between the two groups. There was a similar ease of advancement of the two tracheal tubes. CONCLUSIONS: When performing elective flexible fiberoptic bronchoscopy for intubation, we recommend using the less expensive warmed standard tracheal tube.

Bronchoscopes↗

PubMed2001

Machine classification of dental images with visual search.

RATIONALE AND OBJECTIVES: The authors performed this study to assess the performance of a computer-based classification system that uses gaze locations of observers to define the subspace for machine learning. MATERIALS AND METHODS: Thirty-two dental radiographs were classified by an expert viewer into four categories of disease of the periapical region: no disease (normal tooth), mild disease (widened periodontal ligament space), moderate disease (destruction of the lamina dura), and severe disease (resorption of bone in the periapical area). There were eight images in each category. Six observers independently viewed the images while their eye gaze position was recorded. They then classified the images into one of the four categories. A sample of image space was used as input to a machine learning routine to develop a machine classifier. Sample space was determined with three techniques: visual gaze, random selection, and constrained random selection. K analyses were used to compare classification accuracies with the three sampling techniques. RESULTS: With use of the expert classification as a standard of reference, observers classified images with 57% accuracy, and the machine classified images with 84% accuracy by using the same gaze-selected features and image space. Results of kappa analyses revealed mean values of 0.78 for gaze-selected sampling, 0.69 for random sampling, 0.68 for constrained random selection, and 0.44 for observers. The use of sample space selected with the visual gaze technique was superior to that selected with both random-selection techniques and by the observers. CONCLUSION: Machine classification of dental images improves the accuracy of individual observers using gaze-selected image space.

Artificial Intelligence↗