Search PubMed⌕ Search

Biomedical subjects

S McDonald

Publications and source records attributed to S McDonald.

At least 55 records · Page 3Linked to original sources
PubMed1999

Exploring the process of inference generation in sarcasm: a review of normal and clinical studies.

This article evaluates two theoretical accounts of how sarcasm is understood; the traditional model, which asserts that listeners derive a counterfactual inference from the sarcastic comment, and relevance theory, which asserts that listeners recognize sarcasm as a scornful echo of a previous assertion. Evidence from normal speakers provides only partial support for both theories. Evidence from brain-injured populations suggests that aspects of the pragmatic process can be arrested in ways not predicted by either theory. It is concluded that sarcasm is more effortful to process than nonsarcastic comments and that inferences about the facts of the situation and the mental state of the speaker (e.g., attitudes, knowledge, and intentions) are important to comprehending sarcasm. It is questioned whether inferences about mental state are relatively more difficult for brain-injured subjects and, if so, whether this is a continuum of difficulty or reflects reliance upon different cognitive processes.

Brain Diseases↗
PubMed1999

Covert orienting and focusing of attention in children with attention deficit hyperactivity disorder.

Performance on the covert visuo-spatial attentional functions of orienting and focusing by a group of ADHD children (n = 20) was compared to that of age and sex-matched control children. In Experiment 1, responses were given to cued targets at valid and invalid locations. In Experiment 2, responses were given to targets presented in small, medium-sized or large visual field locations. For both experiments, the hypotheses that reaction times of ADHD children would be greater than those of control children and that performance would be asymmetrical, were supported. For Experiment 1, ADHD children showed bilaterally greater 'benefits' from having directed attention to the cued location and greater 'costs' in having to relocate the attentional focus than controls. In Experiment 2, the hypothesis that the function of focusing attention by ADHD children may show breakdown in the usual pattern of an increase in reaction time with focus area was partly supported by the finding of similar reaction times to targets presented in medium-sized and large regions of the left visual hemifield. These results have been interpreted as reflecting a stronger anchorage of attention by ADHD children upon a cued location and an inability to shift covert attention easily to an alternative location. The breakdown of the focusing function suggests adoption of similar time response sets across focus area size by the more compromised right hemisphere.

Attention↗
PubMed1999

Searching the right database. A comparison of four databases for psychiatry journals.

Journal coverage is one factor that affects the retrieval of relevant information from bibliographic databases. The aims of this study were to investigate the coverage of databases for psychiatry journals, and to assess the overlap between databases. Psychiatry journals were identified using Ulrich's International Periodicals Directory and then analysed to see which bibliographic databases indexed the most journals. A total of 213 abstracting and indexing services were listed as indexing at least one of the 977 psychiatry journals identified. The four most frequently cited databases (PSYCLIT, EMBASE, BIOSIS and MEDLINE) indexed 506 (52%) of the psychiatry journals. Of these 506 journals, PSYCLIT indexed 367 (73%), EMBASE 337 (67%), BIOSIS 243 (48%) and MEDLINE 236 (47%). Combining the databases with the highest yields (PSYCLIT and EMBASE) increased the number of journals indexed to 461 (91%). The four databases combined accounted for 90% of all psychiatry journals found to be indexed by at least one abstracting and indexing service. More than 400 journals were not indexed at all. Variations in the overlap between PSYCLIT, EMBASE, BIOSIS and MEDLINE, and the high proportion (35%) of journals indexed in only one of these four databases emphasize the importance of searching more than one or even two databases to ensure optimal coverage of the literature.

Abstracting and Indexing↗
PubMed1998

Interpreting ambiguous advertisements: the effect of frontal lobe damage.

Despite intact primary language processes patients with frontal lobe deficits often have impaired communication skills including impaired capacity to understand conversational inference. This study examined the ability of three patients with demonstrated frontal lobe pathology to interpret lexically ambiguous advertisements. When compared to a nonbrain-damaged control group it was found that the frontal lobe patients were poorer at comprehending the abstract or inferred meanings inherent in the advertisements. The pattern of performance across the patients did, nevertheless, differ despite a similar end result. These findings are discussed in relation to theories concerning the contribution of the frontal lobes to language function.

Adult↗
PubMed1998

Requests that overcome listener reluctance: impairment associated with executive dysfunction in brain injury.

Fifteen subjects with suspected executive impairment following brain injury and matched controls were tested on a request production task in which they were required to produce nonconventional requests that would overcome listener reluctance. In comparison to controls, the brain-injured subjects were less likely to produce requests that addressed the obstacle to listener compliance, less likely to produce "other" kinds of strategies, and more inclined to make requests encompassing counterproductive comments. These performances were correlated with independent neuropsychological measures of executive function. It was found that disinhibition was positively correlated to the ability to specify the source of listener reluctance in the request as well as to the tendency to use other kinds of strategies. It was surmised that the association between disinhibition and other strategies may reflect the broad nature of the categories used in which marginally appropriate strategies, categorized as "other," may actually have reflected mildly disinhibited behavior.

Adolescent↗
PubMed1998

Prothrombotic changes in children with sickle cell disease: relationships to cerebrovascular disease and transfusion.

Vascular occlusion has a central role in the pathophysiology of sickle cell disease (SCD) and, although there is little evidence that thrombosis alone is responsible, patients with sickle cell disease are known to have an ill-defined but increased thrombotic risk. The most serious complication of this in childhood is stroke which occurs in 7-10% of children and a further 14% have asymptomatic cerebrovascular disease (CVD) on imaging. We have performed a comprehensive profile of coagulation inhibitors and markers of thrombin generation in 96 children (83 nontransfused [NTx] and 13 transfused [Tx]) with steady-state SCD and 18 healthy sibling controls. The levels of protein S (free and total) and heparin cofactor II were reduced in both the NTx and Tx groups compared to controls and protein C and APC resistance ratios were reduced in the NTx group only. Antithrombin levels were not different from controls. Thrombin-antithrombin complexes and prothrombin fragment F1+2 were increased in both patient groups. In the NTx subgroups with or without CVD there were no differences for any of the parameters measured except for lower haemoglobin levels and higher white cell counts in those with asymptomatic CVD. We conclude that children with SCD have a reduction in levels of the majority of the coagulation inhibitors and increased thrombin generation in the steady-state and these are only partially reversed by transfusion. However, these abnormalities do not appear to play a primary role in the development of cerebrovascular disease.

Activated Protein C Resistance↗
PubMed1998

Total and attributable costs of surgical-wound infections at a Canadian tertiary-care center.

OBJECTIVE: To determine the total and attributable costs of surgical-wound infections in a Canadian teaching hospital. DESIGN: Retrospective incidence series study with chart review and examination of resource utilization attributable to wound infection. The charts of inpatients with wound infections were examined using the Appropriateness Evaluation Protocol (AEP), a validated chart review instrument designed to determine appropriateness of care, modified for wound infections. SETTING: A university referral center in Canada. PATIENTS: Medical records were abstracted from patients with wound infections who underwent an inpatient clean or clean-contaminated procedure during 1991. MEASUREMENTS: During the wound-infection treatment period, the hospital costs associated with providing care were tabulated for all inpatient days and for outpatient and emergency visits. Costs taken into account included nursing salary and benefits, nonphysician professional services, operating room time, laboratory, pharmacy, supplies, ancillary tests, and hotel costs. RESULTS: We identified 108 wound infections. Twenty-two patients required 28 surgical procedures related to a wound infection. Inpatient days totalled 1,116, costing $394,337. Fifty-five emergency and 42 clinic visits occurred, costing $27,193. By applying the AEP to the inpatient days, 833 days, or 10.2 days per case, were directly attributable to the wound infection. The hospital costs for inpatient care attributable to wound infections were $321,533 in total, or $3,937 per infection. Costs were distributed as follows: nursing, 51%; hotel, 14%; pharmacy, 10%; laboratory, 9%; emergency and outpatient clinic, 6%; professional services, 5%; operating room, 3%; and ancillary tests, 2%. CONCLUSIONS: Wound infections contribute markedly to extra days of hospitalization and related costs. The AEP method is applied easily to determine attributable days of care and costs of wound infections, which are necessary to calculate the cost-benefit of infection control programs.

Hospital Bed Capacity, 300 to 499↗
PubMed1998

Incidence of hospital-treated traumatic brain injury in an Australian community.

This paper reports findings from an incidence study of head trauma in a defined population. In the North Coast Health Region of NSW, 1,259 subjects with head trauma were admitted to hospitals in a 12-month period in 1988. Direct examination of the medical records confirmed brain injury in only 413 of these cases, corresponding to an annual incidence of approximately 100/100,000 resident population. Although most injuries (62.2%) were mild, 38% were serious (either moderate, 20.3%, or severe, 13.6%; and 3.9% died after admission to hospital). Severe brain injury represented an annual incidence of 12/100,000 resident population. Road traffic accidents accounted for a higher proportion of injuries in the severe group in comparison with the other injury groups. Methodological issues involved in case ascertainment of brain injury are discussed.

Adolescent↗
PubMed1997

Sustained platelet glycoprotein IIb/IIIa blockade with oral xemilofiban in 170 patients after coronary stent deployment.

BACKGROUND: Inhibition of platelet aggregation with parenteral glycoprotein (GP) IIb/IIIa receptor blockers can reduce the ischemic complications of angioplasty. Sustained efficacy and safety of protracted GP IIb/IIIa blockade with an orally administered agent have not previously been determined. This study is the first randomized, dose-ranging, single-blind, placebo-controlled trial of xemilofiban, an oral platelet GP IIb/IIIa receptor antagonist, administered to patients after intracoronary stent deployment. The pharmacodynamic efficacy of xemilofiban-induced platelet inhibition and clinical safety of this agent was evaluated during chronic therapy. METHODS AND RESULTS: After elective intracoronary stent deployment, patients were randomized to receive placebo (250 mg ticlopidine P.O. BID) or xemilofiban in doses of 5, 10, 15, or 20 mg P.O. BID. All patients received 325 mg aspirin P.O. QD. Inhibition of ex vivo platelet aggregation in response to 20 micromol/L ADP and 4 microg/mL collagen was measured over time after the initial dose of study drug and at 1 and 2 weeks of chronic therapy. Study drug was discontinued after 2 weeks, and all patients were followed clinically for > or = 30 days. Oral xemilofiban resulted in a dose-dependent inhibition of platelet aggregation in response to both agonists that was sustained through 2 weeks of chronic therapy. Doses of xemilofiban required to achieve > or = 50% inhibition of platelet aggregation were > or = 10 mg, and the duration of inhibition was 8 to 10 hours. No significant hemorrhagic episodes or blood transfusions were observed in this trial. CONCLUSIONS: Oral xemilofiban in doses of > or = 10 mg produced > or = 50% inhibition of platelet aggregation in response to ADP and collagen for 8 to 10 hours after dosing. Platelet inhibition was sustained through 2 weeks of chronic therapy. The optimal duration of oral GP IIb/IIIa blockade to effectively suppress recurrent ischemic events after coronary intervention remains to be determined.

Abciximab↗
PubMed1997

Evidence that the integrin beta3 and beta5 subunits contain a metal ion-dependent adhesion site-like motif but lack an I domain.

The amino-terminal domain of each integrin beta subunit is hypothesized to contain an ion binding site that is key to cell adhesion. A new hypothesis regarding the structure of this site is suggested by the crystallization of the I domains of the integrin alphaL and alphaM subunits (Lee, J.-O., Rieu, P., Arnaout, M. A., and Liddington, R. (1995) Cell 80, 631-638; Qu, A., and Leahy, D. J. (1995) Proc. Natl. Acad. Sci. U. S. A. 92, 10277-10281). In those proteins, an essential metal ion is bound by a metal ion-dependent adhesion site (MIDAS). The MIDAS is presented at the apex of a larger protein module called an I domain. The metal ligands in the MIDAS can be separated into three distantly spaced clusters of oxygenated residues. These three coordination sites also appear to exist in the integrin beta3 and beta5 subunits. Here, we examined the putative metal binding site within beta3 and beta5 using site-directed mutagenesis and ligand binding studies. We also investigated the fold of the domain containing the putative metal binding site using the PHD structural algorithm. The results of the study point to the similarity between the integrin beta subunits and the MIDAS motif at two of three key coordination points. Importantly though, the study failed to identify a residue in either beta subunit that corresponds to the second metal coordination group in the MIDAS. Moreover, structural algorithms indicate that the fold of the beta subunits is considerably different than the I domains. Thus, the integrin beta subunits appear to present a MIDAS-like motif in the context of a protein module that is structurally distinct from known I domains.

Amino Acid Sequence↗
PubMed1997

A scoring system for the prediction of successful delivery in low-risk birthing units.

OBJECTIVE: To establish and test the effectiveness of a low-risk scoring system to predict obstetric outcome for the selection of women suitable for confinement in low-intervention units. METHODS: Retrospective analyses were performed on data from 2900 women enrolled in the Western Australian Pregnancy Cohort Study and 1353 women managed at a midwifery-based birth center. A combination of the principal predictors of obstetric outcome, incorporating a previously published scoring system and various clinical features, was used to exclude high-risk cases at 18 weeks' and 36 weeks' gestation. Stepwise multivariate logistic regression analyses of the remaining pregnancies then produced a low-risk scoring system. RESULTS: This system predicted a 55% chance of an uncomplicated delivery in a midwifery-based setting after allocating 54% of women to the low-risk category. It predicted an 82% chance of an uncomplicated delivery in a primary medical care setting with the allocation of 84% of women as low risk. CONCLUSION: The results of this study suggest that adding induction and augmentation of labor, together with low pelvic instrumental delivery, to the treatment options in a low-intervention unit would raise the rate of successful confinement within the unit from 55% to 82%. Our scoring system now requires prospective evaluation to further assess its clinical value.

Adult↗
PubMed1997

Poly(DL-lactide-co-glycolide)-encapsulated plasmid DNA elicits systemic and mucosal antibody responses to encoded protein after oral administration.

We have developed a method for the encapsulation of plasmid DNA in poly(DL-lactide-co-glycolide) microparticles. Encapsulated DNA, expressing the insect protein luciferase under the transcriptional control of the human cytomegalovirus immediate early promoter, was administered to mice by intraperitoneal injection or oral gavage. Intraperitoneal injection of encapsulated DNA elicited good serum IgG and IgM responses, and a modest IgA response. Oral administration stimulated good serum antibody responses in all three classes, and in addition, significant levels of mucosal IgA. PLG encapsulation thus has the ability to protect plasmid DNA against degradation after administration, and to facilitate its uptake into appropriate cells for the subsequent expression and presentation of antigen, in such a way as to elicit both systemic and mucosal antibody responses. These findings may have major implications for the design of novel vaccines and delivery strategies.

Administration, Oral↗
PubMed1997

The three faces of performance measurement: improvement, accountability, and research.

In the current climate of public accountability, many clinicians have become uncomfortable with any efforts to create measurement systems. That is unfortunate because measurements are absolutely essential to efforts for improving the processes of medical care. In their guideline implementation and measurement efforts, ISCI and the IMPROVE Project in Minnesota have gradually learned how to distinguish between measurement for improvement and that for accountability. Both approaches are different from the approach that physicians are used to in their encounters with medical research. Understanding these differences and respecting the confidentiality of individual medical groups has been crucial to moving past confusion and suspicion to genuine improvement actions involving multiple medical groups and their contracting managed care plans.

Contract Services↗
PubMed1997

Importance of the tubulointerstitium in human glomerulonephritis. II. Distribution of integrin chains beta 1, alpha 1 to 6 and alpha V.

Accumulation of extracellular matrix is important in the progression of glomerulonephritis. Since adherent cell types utilize integrins to bind and organize extracellular matrix proteins, we have assessed expression of the beta 1 integrins in sequential sections from 85 human renal biopsies and 4 normal kidneys by immunohistochemical staining. Our results demonstrate strong correlations between expression of the alpha 5 chain within the interstitium, the alpha V chain on proximal and distal tubular epithelium and the presence of chronic histological damage. Moreover, staining for interstitial alpha 5 and proximal and distal tubular alpha V were also strongly associated with expression of certain adhesion molecules (ICAM-1, VCAM-1, E-selectin and L-selectin) and the presence of macrophages within the interstitium, which have been linked, in an earlier study, with the degree of chronic histological damage and disease progression. However, in contrast to our earlier study of adhesion molecules, there were also associations between expression of integrin chains within the glomerulus and tubulointerstitium. For example, there were strong positive associations between staining for alpha 5 on glomerular endothelium and its expression on extraglomerular vascular endothelium and between both mesangial alpha 1 and podocyte alpha 3 and tubular staining for the common beta 1 subunit. While the functional significance of these associations is obscure, they suggest some kind of communication between cells in different sites in the kidney. There were also positive associations between staining for different integrins within the glomerulus, notably mesangial cell staining for alpha 2, glomerular endothelial cells staining for alpha 5 and glomerular epithelial cell alpha 3. These results suggest that there is a coordinated upregulation of integrin expression both within the tubulointerstitium and the glomerulus and that at least some of these integrins (interstitial alpha 5 and distal tubular alpha V) are associated with the expression of other adhesion molecules, macrophage infiltration and the presence of markers of disease progression (interstitial fibrosis and tubular atrophy).

Antigens, CD↗
PubMed1997

Suitability of preadmission blood samples for pretransfusion testing in elective surgery.

BACKGROUND: North American transfusion guidelines do not stipulate a time limit between drawing the specimen for pretransfusion testing and giving the transfusion to patients who have not received a transfusion or been pregnant in the preceding 3 months. British guidelines suggest that separated plasma and serum can be stored at -30 degrees C for up to 6 months, but they draw attention to the paucity of evidence concerning the use of stored samples. In Australia, transfusion guidelines recommend a maximum of 10 days' validity for pretransfusion specimens, which requires the patient to present for pretransfusion testing within 10 days of admission or to undergo retesting after admission, which in turn necessitates additional time in the hospital before operation. The study was performed to document the safety of using for pretransfusion testing a blood sample collected more than 10 days before surgery. STUDY DESIGN AND METHODS: Samples from 500 patients scheduled for elective surgery who had not been pregnant or received a transfusion in the previous 3 months were separately tested in blood group and antibody screens at an interval from 11 to 335 days before admission and again on admission. RESULTS: No clinically significant change was detected in the red cell antibody status of the paired samples of any patient. CONCLUSION: For patients who have not been transfused or pregnant in the previous 3 months, it is safe to crossmatch blood for transfusion by using a sample collected well in advance of elective surgery and stored at -30 degrees C.

Blood Grouping and Crossmatching↗
PubMed1997

Test-retest reliability of information about employment provided in surveys by people with spinal cord injuries.

Agreement was examined between the answers to an employment survey administered to discharged patients with spinal cord injury on two occasions 6 mo. apart. Analysis suggested reasonable test-retest reliability, with kappas ranging from .65 to .87 for the categorical data, e.g., current employment information and amount of time before respondents achieved any return to work.

Adult↗