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Biomedical subjects

S Duncan

Publications and source records attributed to S Duncan.

At least 19 recordsLinked to original sources
PubMed1992

Acute rejection of lung allografts with various immunosuppressive protocols.

Between February 1990 and December 1991, 69 patients who survived for a minimum of 5 days after single-lung (27), double-lung (32), or heart-lung transplantation (10) were studied to learn the incidence and severity of acute rejection and the possible effects of various immunosuppressive protocols on this rejection. Acute rejection was less common (2.1 versus 3.1 episodes/patient) after transplantation in those 30 candidates who received rabbit antithymocyte globulin for the first 5 postoperative days versus the 28 who were maintained on cyclosporine, azathioprine, and prednisone alone (p < 0.05), but no patient escaped at least one episode. Patients given cyclosporine received more 3-day courses of methylprednisolone (p < 0.02) than those given rabbit antithymocyte globulin (2.5 versus 1.7 courses). Although no disadvantage in terms of infectious morbidity was noted in the rabbit antithymocyte globulin group, no obvious intermediate advantage was noted in survival (85% at 12 months) or grade of rejection or airway flows. The most common histopathologic grades were mild (A2) and moderate (A3); the average grade was A2.3. FK 506 was tested in 11 patients, and early results are promising relative to low early and likely fewer late episodes of rejection. No differences were noted in the likelihood of rejection for any procedures.

Acute Disease↗
PubMed1992

Interictal HM-PAO SPECT: a routine investigation in patients with medically intractable complex partial seizures?

Single photon emission computed tomography (SPECT) is increasingly being used as an adjunctive technique in the localisation of epileptogenic foci prior to surgery. As yet, few studies have been undertaken to establish the clinical associations of areas of reduced cerebral perfusion. Sixty-three consecutive patients (15 male, 48 female; median age 30 years, range 14-57 years) with medically intractable complex partial seizures (median/month 8, range 1-36) were investigated as outpatients. All had normal high resolution computerised X-ray tomography (CT) of brain. Twenty-seven (47%) exhibited significant perfusion defects on SPECT scanning with a rotating gamma camera system using Tc-99 HM-PAO. There were no significant differences between patients with normal and abnormal scans in terms of age at scanning or at onset of epilepsy or number of seizures. Patients with perfusion defects did, however, have longer median histories of epilepsy than those with normal scans (normal: 10 years, abnormal: 22 years; P = 0.01). Patients with abnormal scans were no more likely to have suffered febrile convulsions in early childhood. The correlation of abnormal SPECT scans with routine surface EEG recordings was poor with only 41% of cases showing clear agreement between the site of hypoperfusion and focal epileptic activity. It is not yet possible to predict clinically those patients who will exhibit perfusion defects on interictal TC-99 HM-PAO SPECT scanning.

Adolescent↗
PubMed1992

Proliferation of cytomegalovirus-primed lymphocytes in bronchoalveolar lavages from lung transplant patients.

Previous reports have described an association between cytomegalovirus infection and increased donor-specific alloreactivity of bronchoalveolar lavage (BAL) lymphocytes in transplanted lungs and a higher risk of bronchiolitis obliterans due to chronic rejection. We have postulated that during infection, intragraft CMV-specific lymphocytes are activated and release lymphokines that augment cellular rejection. This study deals with an analysis of CMV antigen induced proliferation of 28 BAL lymphocyte and 27 peripheral blood lymphocytes samples from 17 lung transplant patients with or without CMV infection. Kinetic studies of lymphocyte proliferation have shown that CMV infection of the lung allograft is associated with an accelerated response of BAL lymphocytes but not PBL, following in vitro exposure to CMV antigen. These findings indicate an accumulation of primed CMV-specific lymphocytes within the lung allograft during CMV infection. Evidence has also been obtained that primed CMV-specific lymphocytes may persist for months in BAL. We conclude that the CMV antigen induced proliferation assay is useful for studies of CMV infection in transplant patients.

Antigens, Viral↗
PubMed1992

A survey of prescription label preferences among community pharmacy patrons.

Fifty-five randomly selected community pharmacy patrons were surveyed regarding their preferences between four different prescription labels. The variables displayed on the four labels were: (i) laser printed, (ii) dot-matrix printed, (iii) glossy surface, and (iv) matt surface. The study population was stratified by age and gender. Statistical analysis of the results indicated a clear preference by all groups for the laser printed labels (P less than 0.001), and the only other statistically significant finding was the preference for the matt surface (P less than 0.05) of females between the ages of 16 and 39. The implications for these differences on label readability are discussed, and recommendations are offered for the use of improved laser technology for computer-generated prescription labels.

Adolescent↗
PubMed1991

Categories and particulars: prototype effects in estimating spatial location.

A model of category effects on reports from memory is presented. The model holds that stimuli are represented at 2 levels of detail: a fine-grain value and a category. When memory is inexact but people must report an exact value, they use estimation processes that combine the remembered stimulus value with category information. The proposed estimation processes include truncation at category boundaries and weighting with a central (prototypic) category value. These processes introduce bias in reporting even when memory is unbiased, but nevertheless may improve overall accuracy (by decreasing the variability of reports). Four experiments are presented in which people report the location of a dot in a circle. Subjects spontaneously impose horizontal and vertical boundaries that divide the circle into quadrants. They misplace dots toward a central (prototypic) location in each quadrant, as predicted by the model. The proposed model has broad implications; notably, it has the potential to explain biases of the sort described in psychophysics (contraction bias and the bias captured by Weber's law) as well as symmetries in similarity judgments, without positing distorted representations of physical scales.

Adolescent↗
PubMed1991

Tracheomalacia and bronchopulmonary dysplasia.

Wheezing in the infant with bronchopulmonary dysplasia results from various pathophysiologic mechanisms, including upper or central airway obstruction. We report an infant with bronchopulmonary dysplasia who presented with episodic wheezing associated with hypoxia and bradycardia without evidence of stridor. Bronchoscopy revealed the presence of tracheomalacia. Upper or central airway obstruction, if undiagnosed, may be life-threatening. We suggest that wheezing with hypoxia and bradycardia in neonates should alert the physician to the possibility of tracheomalacia, even in the absence of audible stridor. Infants presenting with these symptoms should undergo bronchoscopy to confirm the diagnosis.

Adult↗
PubMed1991

Snoring (I). Daytime sleepiness in regular heavy snorers.

Fifteen men, mean (means) age 44 years, were investigated. Their means body mass index was 21.9 kg/m2, and all of them had a respiratory disturbance index below 5 and had good nocturnal oxygen saturation. The subjects were monitored several nights both with and without the following devices: a tight-fitting facial mask, a pneumotachometer, and an esophageal balloon. They were also monitored with and without nasal continuous positive airway pressure. The Multiple Sleep Latency Test was administered after three of the experimental nights (after the baseline nights and after the second nasal CPAP night). Determination of short EEG arousals during nocturnal sleep, which lasted 2 to 10 s, was performed. The relationship between short EEG arousals, the esophageal pressure nadir, and airflow decrease was investigated. We also determined the relationship between clinical reporting of decrease in daytime alertness and MSLT results, and the relationship between MSLT results and the frequency of EEG arousals. The monitoring indicated that heavy snorers may present significant increase in Pes nadir with abrupt decrease in flow leading to EEG arousals. The frequency at which EEG arousals occur has an impact on MSLT scores. Nasal CPAP improves MSLT scores and eliminates these respiration-related EEG arousals. Some heavy snorers without obstructive sleep apnea syndrome may be at risk of having a decrease in daytime alertness.

Adult↗
PubMed1991

Endogenous N-nitrosation and cancer of the biliary tract.

Evidence is presented that N-nitroso compounds occur in bile from patients who have undergone surgery for gallstones or had gastrectomy and from unoperated persons. It is unlikely, therefore, that local formation of nitrosamines can account for the excess risk for gallbladder cancer in the first two groups. Gastric formation remains the likeliest hypothesis.

Bile↗
PubMed1991

The "natural history" of the transplanted lung: rates of pulmonary functional change in long-term survivors of heart-lung transplantation.

Long-term pulmonary function in HLT is well preserved with no evidence of functional decline as a result of transplant "aging," providing the allografts remain free of complications. Long-term survivors with OB appear to be able to maintain adequate oxygenation despite the marked alterations of pulmonary function. The ability to preserve gas exchange at reasonable levels of oxygenation may be the factors permitting extended survival with OB for mean periods of 36.0 months or greater. Preliminary studies suggest that a declining FEF50/FVC, at a time when pulmonary function is normal, may be an index of impending airway disease. Physiologically, from a long-term point of view, HLT remains a viable option for selected patients with end-stage cardiopulmonary disease.

Bronchiolitis Obliterans↗
PubMed1990

Achieving parent-child coordination through convention: fixed- and variable-sequence conventions.

Convention provides a major means by which the child can achieve coordinated action with others. One aspect of the structural design of conventions is considered: the composition of a convention's interaction rules. Fixed-sequence conventions, defined as having only obligatory rules, are differentiated from variable-sequence conventions, having at least 1 optional rule. Some interactional effects of the 2 types of conventions are illustrated by a set of fixed- and variable-sequence conventions hypothesized for interaction within 2 families. Fixed- and variable-sequence conventions are placed within the larger context of the state sensitivity of conventions: the degree to which each convention provides both for participants' expressing convention-relevant states and changes in these states, and for their accommodating the interaction to these states and changes--all relevant to achieving coordinated action. The interactional effects of other major sources of state sensitivity are considered and contrasted with those of fixed- and variable-sequence conventions.

Communication↗
PubMed1989

Benzodiazepine antagonism does not provoke a stress response.

Acute anxiety reactions have been reported following antagonism of benzodiazepine-induced sedation. In this study, the level of sedation and anxiety was assessed in 30 patients randomly assigned to receive either saline or flumazenil (a benzodiazepine antagonist) after midazolam sedation according to a double-blind protocol. Carefully titrated doses of flumazenil, 0.8 +/- 0.2 mg (mean +/- SD), effectively reversed residual midazolam-induced sedation without producing significant changes in the patients' level of anxiety. In addition, plasma epinephrine, norepinephrine, vasopressin, and beta-endorphin concentrations were measured in a subset of patients (n = 5) from each group. The levels of these stress hormones did not acutely change following flumazenil (or saline). These results indicate that flumazenil, 0.6-1.0 mg iv, can antagonize midazolam sedation without producing acute anxiety or evidence of a stress response.

Adult↗
PubMed1988

The development of a role charter for nursing unit administrators.

Issues of decentralization and changes in the structure of the traditional Head Nurse role were motivating factors for the proactive stance taken by the Medical-Surgical Head Nurse Group at The Wellesley Hospital. Increasing frustration with the conventional role and the need for a reflective performance appraisal tool provided further impetus for the development of a revised job description. The three departments of nursing each submitted their perception of the role. A task force was established whose mandate was to review and revise the three separate submissions and combine them into a composite document. This article describes the process from the initial motivating factors to the development of a cohesive Total Head Nurse Group and finally a 'Role Charter for Nursing Unit Administrators.'

Humans↗
PubMed1986

High-performance liquid chromatography analysis of the thiobarbituric acid adducts of malonaldehyde and trans,trans-muconaldehyde.

A reversed-phase HPLC method is described for the separation and analysis of the thiobarbituric acid (TBA) adducts of the reactive aldehydes muconaldehyde (MUC) and malonaldehyde (MDA). The TBA adduct of malonaldehyde was synthesized, purified, and its structure elucidated, for use as standard in quantitative HPLC studies. A detection limit of 1 X 10(-14) mol was achieved for the MUC:TBA and MDA:TBA adducts using the double monochromator fluorometric detector, 7 X 10(-13) mol was the detection limit using a variable wavelength uv-visible detector. Direct on-line identification of the eluting aldehyde:TBA adducts was achieved by the use of a diode-array uv-visible detector. The chromatographic behavior of the adducts under different mobile phase conditions was also examined. This HPLC methodology was used for the identification of muconaldehyde as a product of benzene oxidation in a hydroxyl radical generating system.

Aldehydes↗