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Biomedical subjects

B Wild

Publications and source records attributed to B Wild.

At least 19 recordsLinked to original sources
PubMed2000

Video camera and light system for application in magnetic resonance scanners.

The direct observation and simultaneous recording of subject behavior, e.g. facial movements, during MR imaging is necessary for a variety of functional imaging studies involving phenomena such as emotions, humor, mood, etc. Such observation is also valuable for the monitoring of very ill or young patients. We describe a color video camera and light system which works within the functioning scanner. The camera acquires high resolution video sequences during conventional T(1)-weighted and functional T(2)*-weighted imaging. When fixed to the head coil artefacts during the MRI-acquisition were insignificant. The video allows observation of the face detailed enough to permit FACS scoring of facial expressions. We therefore propose that it can be applied for a wide variety of studies needing visual feedback of subject behavior.

Artifacts↗
PubMed2000

A sampling approach to biases in conditional probability judgments: beyond base rate neglect and statistical format.

Conditional probability judgments of rare events are often inflated. Early accounts assumed a general deficit in using statistical base rates. More recent approaches predict improvement when problems are presented in frequency format or refer to natural categories. The present theory focuses on sampling processes. Experiment 1 showed that a seeming advantage of frequency over probability formats is due to a confounded factor, the need to mentally transform stimulus samples. An information search paradigm was used in Experiment 2. When sampling by the predictor, the probability to be estimated, p(criterion/predictor), was conserved in the samples and judgments were quite accurate. However, when sampling by the criterion, the low base-rate event was strongly overrepresented, accounting for the entire bias. Judgments were quite sensitive to the sampled data, but failed to take sampling constraints into account, as shown in Experiments 3 and 4.

Adult↗
PubMed1999

Reversal of metabolic block in glycolysis by enzyme replacement in triosephosphate isomerase-deficient cells.

Inherited deficiency of the housekeeping enzyme triosephosphate isomerase (TPI) is the most severe clinical disorder of glycolysis. Homozygotes manifest congenital hemolytic anemia and progressive neuromuscular impairment, which in most cases pursues an inexorable course with fatal outcome in early childhood. No effective therapy is available. Hitherto specific enzyme replacement has not been attempted in disorders of glycolysis. Primary skeletal muscle myoblasts and Epstein-Barr virus (EBV)-transformed lymphoblastoid cell lines generated from homozygous TPI-deficient patients were cultured in the presence of exogenous enzyme or cocultured with human K562 erythroleukemia cells as an exogenous source of TPI. Uptake of active enzyme by TPI-deficient cells resulted in reversal of intracellular substrate accumulation, with a reduction in dihydroxyacetone phosphate (DHAP) concentration to levels seen in TPI-competent cells. Evidence of successful metabolic correction of TPI deficiency in vitro establishes the feasibility of enzyme replacement therapy, and has important implications for the potential role of allogeneic bone marrow transplantation and gene therapy as a means of sustained delivery of functional enzyme in vivo.

Adolescent↗
PubMed1998

Measuring the impact of conjugate vaccines on invasive Haemophilus influenzae type b infection in Western Australia.

Haemophilus influenzae type b (Hib) causes serious infections in 26-59 per 100,000 non-Aboriginal Australian children under five years of age. Aboriginal children suffer much higher rates of infection (> or = 150 per 100,000), and at an earlier age, and have a greater risk of death and disability due to Hib infection. In 1992 and 1993, four conjugate Hib vaccines were introduced in Australia, and a nationally funded program of infant vaccination was begun in July 1993. This study aimed at evaluating the effectiveness of Hib vaccination in Aboriginal and non-Aboriginal children in Western Australia using a population-based active surveillance system for non-Aboriginal children and a case control study for Aboriginal children. The incidence of invasive Hib disease in non-Aboriginal children fell from 30.9 per 100,000 before vaccination was available to 6.3 per 100,000 in the second year after its introduction. The vaccine efficacy was estimated to be 80 per cent for Aboriginal children (odds ratio 0.20, 95 per cent CI 0.01-2.76) and, after adjustment for confounders, 75 per cent (odds ratio 0.25, CI 0.02-3.66). Based on the adjusted value (75 per cent), and using a Bayesian approach, we estimate that the posterior probability was 0.55 that the true vaccine efficacy is greater than 70 per cent, and 0.69 that the efficacy is greater than 50 per cent. We conclude that Hib vaccination is effective in preventing invasive Hib disease in Aboriginal and non-Aboriginal children in Australia.

Bacteremia↗
PubMed1997

Cerebellar hypermetria: reduction in the early component of the antagonist electromyogram.

Several articles have described the electromyographic (EMG) patterns underlying cerebellar hypermetria. However, the description of the EMG associated with hypermetria is not consistent between studies. It is hypothesized that the reason for this concerns the criteria used to define and describe the antagonist latency. Several studies on neurologically normal individuals have shown that there are two components to the antagonist EMG: an early component and a late component. However, many studies have identified only one component and have not defined whether it was the early or late component. A reanalysis of one published data set that had previously identified only one antagonist component was performed. The reanalysis suggests that hypermetria can be caused by an absence of an early antagonist EMG component, a delayed late component, or both. In addition, a new measure is suggested that allows this hypothesis to be further evaluated.

Cerebellar Diseases↗
PubMed1996

Acceleration deficit in patients with cerebellar lesions. A study of kinematic and EMG-parameters in fast wrist movements.

Slowness of goal-directed movements is a frequent symptom following cerebellar lesions. So far it has not been demonstrated whether this slowness represents compensation for impaired braking which is a feature of cerebellar dysfunction with the consequence of hypermetria, or whether it is an independent part of cerebellar movement disorder. To resolve this question we tested 18 cerebellar patients in a paradigm where they not only had to perform fast goal-directed wrist flexion movements (amplitudes 5 degrees and 30 degrees) but also wrist flexion movements as fast and large as possible without particular target. In normals antagonist activity is minimal in large movements without target. Although subjects were clinically only mildly affected they regularly showed a 'slowness of movement' resulting from a reduction of peak acceleration. This in turn was due to the reduced generation of agonist activity. Peak velocity was not significantly decreased because the acceleration phase was adequately prolonged. Since these changes were most pronounced in the 'fast' movements without target the compensation hypothesis should be discarded. The reduction of acceleration must at least partially be due to a genuine cerebellar deficiency in the fast generation of agonist activity.

Adolescent↗
PubMed1993

Cerebellar ataxia in ataxic hemiparesis? A kinematic and EMG analysis.

It has recently been proposed that the ataxia in ataxic hemiparesis is a clumsiness common to all patients with hemiparesis and not indicative of any involvement of corticopontocerebellar or cerebellocortical pathways. In disagreement with this view, we report here that a patient with ataxic hemiparesis, following a lesion of the corona radiata, showed the disorders in kinematic and electromyographic (EMG) parameters of goal-directed movements that have recently been demonstrated to be characteristic of patients with cerebellar lesions. This suggests involvement of corticopontocerebellar or cerebellocortical pathways in ataxic hemiparesis.

Adult↗
PubMed1991

Cerebellar dysmetria at the elbow, wrist, and fingers.

1. The objective was to investigate in cerebellar patients with dysmetria the kinematic and electromyographic (EMG) characteristics of large and small movements at the elbow, wrist, and finger and thereby to determine the nature of cerebellar dysmetria at distal as well as proximal joints. Flexions were made as fast as possible by moving relatively heavy manipulanda for each joint to the same end position through 5, 30, and 60 degrees. 2. In normal subjects flexions at all joints were accompanied by similar triphasic EMG activity. Movements of increasing amplitude were made with increasing movement durations and increasing durations and magnitudes of initial agonist EMG activity. Antagonist activity often appeared to have two components: one coactive with the initial agonist burst but starting later, the other reaching its peak at about peak velocity. 3. Cerebellar patients with dysmetria showed hypermetria followed by tremor at all three joints when movements were made with the manipulanda. Hypermetria was most marked for aimed movements of small amplitude (5 degrees) at all joints. 4. A characteristic of cerebellar disordered movements, which could be present at all amplitudes and all joints, was an asymmetry with decreased peak accelerations and increased peak decelerations compared to normal movements. Both the asymmetry and the hypermetria for small amplitude movements could be used clinically as sensitive indicators of cerebellar dysfunction. 5. The EMG abnormalities accompanying hypermetria and asymmetry were a more gradual buildup and a prolongation of agonist activity and delayed onset of antagonist activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1965

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Interprofessional Relations↗
PubMedDate not supplied

The consequence of nucleotide substitutions in the triosephosphate isomerase (TPI) gene promoter.

Mutations at -5A-->G, -8-->GA within the cap proximal element (CPE), and -24T-->G within the TATA box of the triosephosphate isomerase (TPI) gene promoter have been identified in populations with a wide geographical distribution. These mutations lie within, or in close proximity to, known cis-active elements in the TPI gene promoter. To determine the functional significance of mutation at these sites, which remains controversial, their effect on the expression of erythrocyte TPI enzyme activity was studied in 110 healthy unrelated subjects. The -5G mutation did not alter erythrocyte TPI level, whereas the -8A mutation was accompanied by a significant reduction in enzyme activity to around 90% and 76% of normal erythrocyte TPI activity in heterozygotes and homozygotes, respectively. The -8A -24G genotype was associated with 75% of normal TPI activity in a heterozygote studied, implying that substitution of G at position -24 within the canonical TATA motif causes an additive decrease in TPI gene transcription in erythroid cells. A DNA-protein complex of 125kDa which was competitively blocked by specific unlabelled oligomers was demonstrated at the CPE and TATA box by electrophoretic mobility shift analysis. These findings provide direct evidence that TPI promoter mutations are linked to a reduction of TPI enzyme activity in vivo.

Binding Sites↗
PubMedDate not supplied

Goal post injuries in soccer. A laboratory and field testing analysis of a preventive intervention.

Soccer is the most popular team sport worldwide, with approximately 40 million amateur participants. Most fatalities in soccer are related to player impact with the goal post. This study focuses on two case reports, a laboratory testing phase, and a pilot field testing phase of preventive equipment that can be used around the goal to prevent injury. Horizontal and vertical impact testing in the laboratory revealed impact force was diminished when the goal post was covered with protective padding (reduction of 31% and 63%) (P < 0.05). These data showed a statistically significant decrease in force at all temperatures. In the pilot field testing phase of the study, 471 games were monitored. Soccer teams participating in youth, teen, and adult soccer leagues were included in this phase of the study. During the 3-year study, there were seven player collisions with padded goal posts, and no injuries were recorded. The use of padded goal posts within the game of soccer has been documented to reduce the possibility of injury, both in the laboratory phase and in the pilot field testing phase.

Athletic Injuries↗