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Biomedical subjects

W Hutchison

Publications and source records attributed to W Hutchison.

11 recordsLinked to original sources
PubMed2000

Long-term follow-up of unilateral pallidotomy in advanced Parkinson's disease.

BACKGROUND: Although the short-term benefits of posteroventral pallidotomy for patients with advanced Parkinson's disease have been well documented, little is known about the long-term outcome of the procedure. METHODS: We conducted a long-term follow-up study of a cohort of 40 patients who had undergone unilateral posteroventral medial pallidotomy between 1993 and 1996. Twenty patients were not evaluated because they had undergone a second surgical procedure (11 patients) or had died (2) or because they had dementia or another debilitating illness (4), lived too far away (1), or had been lost to follow-up (2). We conducted serial postoperative assessments of parkinsonism in the remaining 20 patients while they were taking medications ("on" period) and after overnight withdrawal of the drugs ("off" period). The mean follow-up time was 52 months (range, 41 to 64). RESULTS: The combined off-period score for activities of daily living and motor function on the Unified Parkinson's Disease Rating Scale was 18.0 percent better at the last evaluation than at base line (95 percent confidence interval, 4.9 to 31.0 percent; P=0.01). Significant improvements were also evident in the off-period scores for contralateral tremor (65.4 percent improvement, P=0.007), rigidity (43.2 percent, P=0.03), and bradykinesia (18.2 percent, P=0.04) and in the on-period score for contralateral dyskinesia (70.6 percent, P<0.001). Changes in medication did not contribute to the sustained improvement. The 20 patients who could not be included in the long-term analysis had similar base-line characteristics but a worse response to surgery at six months. CONCLUSIONS: In the group of patients with advanced Parkinson's disease who could be enrolled in our long-term follow-up study of unilateral posteroventral medial pallidotomy (20 patients from the original cohort of 40), significant early improvements in off-period contralateral signs of parkinsonism were sustained for up to five and a half years. There was a sustained significant improvement in on-period contralateral dyskinesia but not in other on-period signs of parkinsonism.

Activities of Daily Living↗
PubMed2000

Neuronal recordings in Parkinson's disease patients with dyskinesias induced by apomorphine.

Dopaminergic agents reverse parkinsonism but commonly induce dyskinesia in patients with Parkinson's disease (PD) on long-term levodopa therapy. The aim of this study was to determine the neurophysiologic correlates of the amelioration of parkinsonism and the involuntary movements produced by the dopamine agonist apomorphine. Seventeen PD patients were given apomorphine (2-6 mg) before surgery. Neural activity was recorded for individual neurons and for populations of neurons before and after apomorphine. Both internal (GPi) and external (GPe) segments of the globus pallidus were sampled in patients undergoing pallidal surgery. The subthalamic nucleus (STN) was sampled in STN surgery patients. Results suggest that dopaminergic agents act by decreasing GPi and STN activity, and increasing GPe activity, and that drug-induced dyskinesias results from a large reduction in GPi firing.

Action Potentials↗
PubMed1998

Pallidal stimulation in Parkinson's disease patients with a prior unilateral pallidotomy.

OBJECTIVE: To evaluate, in a double-blind fashion, the efficacy of deep brain stimulation of the internal segment of the globus pallidus (GPi) contralateral to a previous unilateral medial pallidotomy (MP). METHODS: This pilot study involved 4 patients with a previous MP and one previously unoperated patient unable to tolerate any antiparkinsonian drugs. One of the patients with a prior unilateral MP had two electrodes implanted in the contralateral side, one in GPi and one in Vim thalamus. Detailed neurologic assessments were performed after overnight drug withdrawal and in the drug "on" state at baseline, 1 week and 3 months (in all), and 9 and 12 months (one) with patients and evaluators blinded to the status of stimulation. RESULTS: GPi stimulation resulted in improvements in "off-period" contralateral bradykinesia, rigidity and tremor in all patients. Dyskinesias and freezing episodes were ameliorated in one patient each but dyskinesias were transiently induced in another. The patient with GPi + Vim electrodes had complete resolution of contralateral tremor with thalamic stimulation but less benefit from acute GPi stimulation. One patient experienced a single seizure one week post-op and no other surgical complications were observed. CONCLUSIONS: Deep brain stimulation can be applied safely and effectively in patients who have already had a pallidotomy on the contralateral side. The effect of stimulation at different sites on different symptom profiles and levodopa-induced dyskinesias requires further evaluation.

Adult↗
PubMed1998

Reduced collagen VI causes Bethlem myopathy: a heterozygous COL6A1 nonsense mutation results in mRNA decay and functional haploinsufficiency.

We have identified a new pathogenic mechanism for an inherited muscular dystrophy in which functional haploinsufficiency of the extracellular matrix protein collagen VI causes Bethlem myopathy. The heterozygous COL6A1 mutation results in a single base deletion from the mRNA and a premature stop codon. The mutant mRNA is unstable, subject to nonsense-mediated mRNA decay, and is almost completely absent both from patient fibroblasts and skeletal muscle, resulting in haploinsufficiency of the alpha1(VI) subunit and reduced production of structurally normal collagen VI. This is the first example of a muscular dystrophy caused by haploinsufficiency of a structural protein or member of the dystrophin-glycoprotein complex, and identifies collagen VI as a critical contributor to cell-matrix adhesion in skeletal muscle.

Cells, Cultured↗
PubMed1997

Utilization and cost savings of a wide-area computer network for neurosurgical consultation.

BACKGROUND AND OBJECTIVE: Telemedicine systems offer many potential advantages for health care delivery. Most reports have centered on the delivery of primary and medical subspecialty care rather than on its impact on patient care and the potential for cost savings. In 1993, we implemented NeuroLink, a wide-area teleradiology network for delivery of specialty care in neurologic surgery at Allegheny General Hospital (AGH). This study was designed to determine the potential cost savings of such a network. METHODS: We prospectively reviewed 100 consecutive telemedicine neurosurgical consultations from 20 western Pennsylvania community hospitals participating in the NeuroLink network. Data related to referring hospital, diagnosis, disposition of the patient, and mode of transportation were reviewed. To determine the potential cost savings, the differential of hospital-based charges between AGH and western Pennsylvania primary hospitals was calculated based on an average length of stay (LOS), patient bed costs, and transportation charges. RESULTS: Of the 100 patients, 33 did not require transfer to a tertiary facility but were instead managed at the community hospital as a direct result of the remote diagnosis and image review disclosing that neurosurgical procedures or intensive care were not required. Cost analysis, comparing the average LOS at AGH with that of the average community hospital, including transportation, showed savings of $502,638. CONCLUSION: Our neurosurgical wide-area computer network has led to more appropriate transfer of patients to a tertiary facility and significant estimated cost savings.

Computer Communication Networks↗
PubMed1996

Methods for microelectrode-guided posteroventral pallidotomy.

Methods for localizing the posteroventral globus pallidus intermus are described. The authors' techniques include the use of microelectrodes to record single-unit activity and to microstimulate in human pallidum and its surrounding structures. This technique allows a precise determination of the locations of characteristic cell types in sequential trajectories through the external and internal segments of the pallidum. The location of the optic tract can be determined from microstimulation-evoked visual sensations and recordings of flash-evoked potentials. In addition, microstimulation-evoked motor and sensory responses allow the internal capsule to be identified. The data collected using this technique are an important adjunct to selecting optimum sites to place electrocoagulation lesions for stereotactic posteroventral pallidotomy for refractory Parkinson's disease.

Catheter Ablation↗
PubMed1987

Human dihydropteridine reductase: characterisation of a cDNA clone and its use in analysis of patients with dihydropteridine reductase deficiency.

Deficiency of human dihydropteridine reductase (hDHPR) causes malignant hyperphenylalaninemia. We report the isolation of a cDNA clone for hDHPR that spans the complete coding region, and present the nucleotide sequence and the predicted amino acid sequence. The hDHPR protein does not share extensive homology with the enzymatically related protein human dihydrofolate reductase. Patients with hDHPR deficiency were analysed for the presence of hDHPR cross-reacting protein, mRNA encoding hDHPR, and chromosomal DNA rearrangements. The results show that this inherited error of metabolism can result from a variety of mutations. However, no major rearrangements were seen in 11 patients analysed by Southern blotting. Three RFLPs were found with the restriction endonucleases AvaII and MspI. These RFLPs are useful for prenatal diagnosis of hDHPR deficiency.

Amino Acid Sequence↗
PubMed1983

Muscle fibre type distribution, muscle cross-sectional area and maximal voluntary strength in humans.

The relationship between maximum voluntary concentric strength, muscle fibre type distribution and muscle cross-sectional areas were examined in 23 subjects (7 female and 11 male phys. ed. students as well as 5 male bodybuilders). Maximal knee and elbow extension as well as elbow flexion torque at the angular velocities 30, 90 and 180 degrees per second was measured. Muscle biopsies were taken from vastus lateralis and m. triceps brachii. The muscle cross-sectional area of the thigh and upper arm was measured with computed tomography scanning. The maximal torque correlated strongly to the muscle cross-sectional area times an approximative measure on the lever arm (body height). Maximal tension developed per unit of muscle cross-sectional area did not correlate significantly with per cent type I fibre area and did not differ between the female and male students or bodybuilders. Neither did the relative decrease in torque with increasing contraction velocity show any significant relationship to the per cent type I fibre area. The total number of muscle fibres was estimated by dividing the muscle cross-sectional area with the mean fibre area of m. triceps brachii. The number of fibres did not seem to differ between the sexes.

Adenosine Triphosphatases↗