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Biomedical subjects

N A Barrett

Publications and source records attributed to N A Barrett.

10 recordsLinked to original sources
PubMed2006

Transfusion-related acute lung injury: a literature review.

Transfusion-related acute lung injury (TRALI) is a serious and potentially fatal complication of transfusion of blood and blood components. TRALI is under-diagnosed and under-reported because of a lack of awareness. A number of models have been proposed to explain the pathogenesis of TRALI: an antibody mediated model; a two-event biologically active mediator model; and a combined model. TRALI can occur with any type of blood product and can occur with as little as one unit. Its presentation is similar to other forms of acute lung injury and management is predominantly supportive. The main strategy in combating TRALI is prevention both through manipulation of the donor pool and through clinical strategies directed at reducing transfusion of blood products including, but not limited to, evidence-based lower transfusion thresholds. This article presents a review of TRALI and addresses the definition, pathology, pathogenesis, clinical manifestations, treatment and prevention of the syndrome.

Humans↗
PubMed2003

Human brain regions required for the dividing and switching of attention between two features of a single object.

This combined PET and ERP study was designed to identify the brain regions activated in switching and divided attention between different features of a single object using matched sensory stimuli and motor response. The ERP data have previously been reported in this journal [64]. We now present the corresponding PET data. We identified partially overlapping neural networks with paradigms requiring the switching or dividing of attention between the elements of complex visual stimuli. Regions of activation were found in the prefrontal and temporal cortices and cerebellum. Each task resulted in different prefrontal cortical regions of activation lending support to the functional subspecialisation of the prefrontal and temporal cortices being based on the cognitive operations required rather than the stimuli themselves.

Adult↗
PubMed2003

Inadvertent intrathecal injection of tramadol.

The present case report describes the observed sequelae following an inadvertent intrathecal injection of tramadol in a patient with metastatic malignancy. The contributing circumstances before the injection are discussed, as is the potential aetiology of the observed sequelae.

Analgesics, Opioid↗
PubMed2001

Human cortical processing of colour and pattern.

The present study investigates human visual processing of simple two-colour patterns using a delayed match to sample paradigm with positron emission tomography (PET). This study is unique in that we specifically designed the visual stimuli to be the same for both pattern and colour recognition with all patterns being abstract shapes not easily verbally coded composed of two-colour combinations. We did this to explore those brain regions required for both colour and pattern processing and to separate those areas of activation required for one or the other. We found that both tasks activated similar occipital regions, the major difference being more extensive activation in pattern recognition. A right-sided network that involved the inferior parietal lobule, the head of the caudate nucleus, and the pulvinar nucleus of the thalamus was common to both paradigms. Pattern recognition also activated the left temporal pole and right lateral orbital gyrus, whereas colour recognition activated the left fusiform gyrus and several right frontal regions.

Adult↗
PubMed1999

An exploration of varieties of visual attention: ERP findings.

A set of five tasks was designed to examine dynamic aspects of visual attention: selective attention to color, selective attention to pattern, dividing and switching attention between color and pattern, and selective attention to pattern with changing target. These varieties of visual attention were examined using the same set of stimuli under different instruction sets; thus differences between tasks cannot be attributed to differences in the perceptual features of the stimuli. ERP data are presented for each of these tasks. A within-task analysis of different stimulus types varying in similarity to the attended target feature revealed that an early frontal selection positivity (FSP) was evident in selective attention tasks, regardless of whether color was the attended feature. The scalp distribution of a later posterior selection negativity (SN) was affected by whether the attended feature was color or pattern. The SN was largely unaffected by dividing attention across color and pattern. A large widespread positivity was evident in most conditions, consisting of at least three subcomponents which were differentially affected by the attention conditions. These findings are discussed in relation to prior research and the time course of visual attention processes in the brain.

Adolescent↗
PubMed1998

Further evidence for a deficit in switching attention in schizophrenia.

In this study, sustained, selective, divided, and switching attention, and reloading of working memory were investigated in schizophrenia by using a newly developed Visual Attention Battery (VAB). Twenty-four outpatients with schizophrenia and 24 control participants were studied using the VAB. Performance on VAB components was correlated with performance of standard tests. Patients with schizophrenia were significantly impaired on VAB tasks that required switching of attention and reloading of working memory but had normal performance on tasks involving sustained attention or attention to multiple stimulus features. Switching attention and reloading of working memory were highly correlated with Trails (B-A) score for patients. The decline in performance on the switching-attention task in patients with schizophrenia met criteria for a differential deficit in switching attention. Future research should examine the neurophysiological basis of the switching deficit and its sensitivity and specificity to schizophrenia.

Adult↗
PubMed1997

The medical student and the suicidal patient.

Today's medical students are being confronted with ethical situations of far greater complexity than were their predecessors and yet the medical education system does little to prepare students for the ethical dilemmas which they inevitably face when entering the hospital environment. The following article addresses the issues surrounding a case where a patient has told a student in confidence of his plans to commit suicide. What should the student do? The only way for the student to prevent death is by breaking confidentiality because the student has insufficient clinical experience to provide adequate guidance. However, this requires ignoring the patient's right to autonomy, a right enshrined in both case law and medical ethics. Clearly the student's ethical, moral and legal position must be carefully evaluated.

Confidentiality↗
PubMed1978

The bioavailability of benorylate in hot beverages.

It has been recommended that benorylate may be administered with hot beverages to overcome the problem of its relative unpalatability. Urine salicylate recovery used as a measure of bioavailability in 20 normal subjects has shown that hot coffee has no significant effect on drug availability from the orally administered suspension.

Adult↗