Biomedical subjects

S M Dunn

Publications and source records attributed to S M Dunn.

At least 19 recordsLinked to original sources

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↗

PubMed2001

Hearing the bad news of a cancer diagnosis: the Australian melanoma patient's perspective.

BACKGROUND: In the past, recommendations on how to break the bad news of a cancer diagnosis have been based on expert opinion. Recently, consensus-based guidelines for medical practitioners have been developed. The objective of this work is to investigate patient preferences for communication practices and to identify any disparities between these guidelines, patient preferences and patient recollections of hearing their diagnosis. PATIENTS AND METHODS: A consecutive sample of 131 newly diagnosed melanoma patients were surveyed approximately 4 months after initial diagnosis to document their preferences and recollections of their communication experiences. RESULTS: Of the 'breaking bad news' recommendations investigated, patients did not strongly endorse the doctor helping tell others of the diagnosis or telling the patient about cancer support services. Very few patients expressed a preference for having another health professional present. One communication feature, the patient feeling confident about getting the best treatment, was endorsed as 'very important' but does not feature in published guidelines. The most notable disparities between guidelines and the reported experiences of patients related to perceived delays in receiving the diagnosis, and having adequate opportunity to ask their clinician questions. CONCLUSION: Current Australian recommendations on how to communicate a diagnosis of cancer were generally supported by the patients' expressed preferences, but several modifications are proposed. IMPLICATIONS: Suggestions are offered to help overcome the disparities identified between recommendations and patients' preferences when a diagnosis of cancer is being communicated.

Adaptation, Psychological↗

PubMed2001

Mutagenesis of the GABA(A) receptor alpha1 subunit reveals a domain that affects sensitivity to GABA and benzodiazepine-site ligands.

We have mutated several amino acids in the region of the GABA(A) receptor alpha1 subunit predicted to form a small extracellular loop between transmembrane domains two and three to investigate its possible role in ligand sensitivity. The mutations were S275T, L276A, P277A, V279A, A280S and Y281F. Mutant alpha1 subunits were co-expressed with beta2 and gamma2 subunits in tsA201 cells or Xenopus oocytes. Binding studies revealed that the only mutation that significantly affected [3H]Ro15-4513 binding was the V279A substitution which reduced the affinity for this ligand. Electrophysiological examination of mutant receptors revealed that L276A, P277A and V279A displayed rightward shifts of their GABA concentration-response curves, the largest occurring with the L276A mutant. The impact of these mutations on allosteric modulation by benzodiazepine-site ligands was examined. V279A reduced the potency of both flunitrazepam and Ro15-4513 but, in each case, their efficacy was enhanced. A280S resulted in a decrease in flunitrazepam efficacy without affecting its potency. Additionally, P277A and A280S resulted in Ro15-4513 losing its inverse agonist effect at these receptors. These results suggest that a domain within this small extracellular loop between TMII-TMIII plays a role in determining the sensitivity of GABA(A) receptors to both GABA and benzodiazepine-site ligands.

Allosteric Regulation↗

PubMed2001

The influence of a bupivacaine and fentanyl epidural infusion after epidural fentanyl in patients allowed to ambulate in early labor.

UNLABELLED: Epidural fentanyl after a lidocaine and epinephrine test dose provides adequate analgesia and allows for ambulation during early labor. This study was designed to determine the influence of an epidural infusion of bupivacaine plus fentanyl administered after initiation of epidural labor analgesia with fentanyl. Specifically, we evaluated whether there is an increase in motor block or an increased time to request for further analgesic medication. Fifty-one laboring primigravid women at <5 cm cervical dilation who requested epidural analgesia were enrolled. After a 3-mL epidural test dose of 1.5% lidocaine with epinephrine (5 microg/mL), patients received fentanyl 100 microg via the epidural catheter. They then randomly received either an infusion (10 mL/h) of 0.0625% bupivacaine with fentanyl (3 microg/mL) or an infusion of preservative-free saline. After the administration of the initial analgesic, pain scores and side effects were recorded for each patient at 10, 20, and 30 min, every 30 min thereafter, and at the time of request for additional analgesic medication, by an observer blinded to the technique used. There were no demographic differences between the two groups. The mean duration of analgesia (time from initial dose to request for additional analgesia) was increased in the group that received a continuous infusion of bupivacaine and fentanyl compared with the Saline group (198 +/- 86 vs 145 +/- 50 min; P < 0.009). Side effects were similar between the two groups. No patient in either group experienced any detectable motor block. Fourteen patients chose to ambulate in the Saline group, and 12 patients chose to ambulate in the Infusion group. In early laboring patients, a continuous infusion of 0.0625% bupivacaine infusion with fentanyl (3 microg/mL) prolonged the duration until top-up was required, after epidural fentanyl 100 microg after a lidocaine and epinephrine test dose, and did not cause any clinically detectable motor block. IMPLICATIONS: A 0.0625% bupivacaine and fentanyl (3 microg/mL) infusion, when added to epidural fentanyl (100 microg), prolongs the analgesic duration without increasing motor block in women in early labor.

Adjuvants, Anesthesia↗

PubMed2001

Biomedical image skeletonization: a novel method applied to fibrin network structures.

To understand the rheological behavior of fibrin clots, we must obtain quantitative measurements of morphometric parameters of the networks formed under various conditions. The networks are so complex that researchers must currently manually segment the images of network samples and estimate the parameters from them. Skeletonization is a promising tool for automating this task. We here propose a method that rapidly constructs a coarse representation of a skeleton graph and, using the snake model, deforms the graph to obtain smooth skeletons. Unlike many existing approaches, our method does not involve explicit object boundary information or high order derivatives. Since our method processes a given image as a whole, the presence of multiple objects in an image is automatically detected and the skeletons of these objects are computed simultaneously.

Algorithms↗

PubMed2000

Roles of agonist-binding sites in nicotinic acetylcholine receptor function.

Under equilibrium conditions, the nicotinic acetylcholine receptor from Torpedo electroplax carries two high affinity-binding sites for agonists. It is generally assumed that these are the only agonist sites on the receptor and that their occupancy results in rapid channel activation followed by slower conformational transitions that lead to the high affinity equilibrium state. These slow transitions are thought to reflect the physiological process of desensitization. Here we show that preequilibration of the high affinity sites with saturating concentrations of carbamylcholine does not diminish the ion flux response to subsequent exposure to higher (activating) concentrations of this agonist. This finding has profound implications with respect to receptor function: (1) occupancy of the high affinity sites per se does not desensitize the receptor and (2) these sites cannot be directly involved in receptor activation. It is thus necessary to invoke the presence of additional binding sites in channel opening.

Animals↗