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Biomedical subjects

W Stephenson

Publications and source records attributed to W Stephenson.

10 recordsLinked to original sources
PubMed2004

Progression of scoliosis after spinal fusion in Duchenne's muscular dystrophy.

A consecutive series of 85 patients with Duchenne's muscular dystrophy who underwent spinal fusion over a period of 16 years was followed up with regard to the progression of the scoliosis and pelvic obliquity. Of 74 patients with adequate radiographic follow-up, 55 were instrumented with the Luque single-unit rod system and 19 with the Isola pedicle screw system; seven were instrumented to L3/4, 42 to L5, 15 to S1 and 10 to the pelvis with intrailiac rods. The mean period of follow-up was 49 months (SD 22) before and 47 months (SD 24) after operation. There was one peri-operative death and three cases of failure of hardware. The mean improvement in the Cobb angle was 26 degrees and in pelvic obliquity, 9.2 degrees. Fusion to L3/4 achieved a poorer correction of both curves while intrapelvic rods, achieved and maintained the best correction of pelvic obliquity. Fusion to S1 did not provide any benefit over more proximal fusion excluding the sacrum, with regard to correction and maintenance of both angles. The Isola system appeared to provide and maintain a slightly better correction of the Cobb angle.

Adolescent↗
PubMed2000

Whiplash injury--are current head restraints doing their job?

It is generally accepted that the incidence of whiplash associated disorders is increasing in all industrialised countries, despite the almost universal fitment of head restraints in at least the front seats of cars. This is usually attributed to the fact that few people can be observed to follow the standard recommendations as regards head restraint positioning, that is, level with the head vertically and as close to the head as possible horizontally. This study set out to determine whether any other factors, in addition to head restraint adjustment, could be found which would influence the severity of whiplash injury. This was done by linking medical assessment of real-world accident victims with engineering assessment of the accident vehicles. A random sample of road accident victims suffering from whiplash associated disorder was studied. The vehicles they had been travelling in were examined to assess impact severity and, where possible, measurements were made of seat and head restraint adjustment with the subject sitting in the vehicle. All subjects were interviewed to assess the disability resulting from their injuries, and their progress was followed for 12 months. The results were subjected to statistical analysis to try to determine relationships between severity of injury (as measured by resultant disability) and a number of occupant- and vehicle-related factors. A significant proportion of the sample had suffered lumbar strain injury in addition to whiplash, and these were excluded from the present analysis. Frontal impact victims suffered symptoms indistinguishable from those of rear impact victims. The beneficial effects of good head restraint adjustment could not be clearly demonstrated, and some trends, especially in rear impacts, where the benefits of a well-adjusted restraint should have been very clear, indicated that larger distances from head to restraint were associated with lower disability. The paper discusses these counter-intuitive results and their implications.

Accidents, Traffic↗
PubMed1998

Molecular characterization of pyruvate carboxylase deficiency in two consanguineous families.

Pyruvate carboxylase (PC) is a biotinylated mitochondrial enzyme that catalyzes the conversion of pyruvate to oxaloacetate. Children with inborn errors of PC metabolism have lactic acidosis, hypoglycemia, and mental retardation. The variable severity of the clinical phenotype is dependent on both genetic and environmental factors. Two consanguineous families with moderate forms of PC deficiency were characterized at the biochemical and molecular levels. In both families, the probands were found to have low PC activity (range, 2-25% of control) in blood lymphocytes and skin fibroblasts associated with either diminished or normal protein levels. In the first case, sequencing of patient-specific PC cDNA demonstrated a T to C substitution at nucleotide 434, which causes a valine to alanine change at amino acid residue 145. Direct sequencing of the parents showed that they are heterozygous for this mutation. In the second family, a brother and sister had mental retardation and episodes of severe lactic/ketoacidosis in early childhood. In these cases, a C to T substitution at nucleotide 1351 results in a cysteine for arginine substitution at amino acid residue 451; the parents were also found to be heterozygous for this mutation. In both families, no other mutations were found, and both substitutions occurred in relatively conserved amino acid residues. These mutations, located in the biotin carboxylase domain, provide a unique opportunity to analyze how natural occurring mutations affect PC function.

Base Sequence↗
PubMed1996

Esophagitis associated with the use of alendronate.

BACKGROUND: Alendronate, an aminobisphosphonate and a selective inhibitor of osteoclast-mediated bone resorption, is used to treat osteoporosis in postmenopausal women and Paget's disease of bone. Aminobiphosphonates can irritate the upper gastrointestinal mucosa. METHODS: We describe three patients who had severe esophagitis shortly after starting to take alendronate and also analyze adverse esophageal effects reported to Merck, the manufacturer, through postmarketing surveillance. RESULTS: As of March 5, 1996, alendronate had been prescribed for an estimated 475,000 patients worldwide, and 1213 reports of adverse effects had been received. A total of 199 patients had adverse effects related to the esophagus; in 51 of these patients (26 percent), including the 3 we describe in case reports, adverse effects were categorized as serious or severe. Thirty-two patients (16 percent) were hospitalized, and two were temporarily disabled. Endoscopic findings generally indicated chemical esophagitis, with erosions or ulcerations and exudative inflammation accompanied by thickening of the esophageal wall. Bleeding was rare, and stomach or duodenal involvement unusual. In patients for whom adequate information was available, esophagitis seemed to be associated with swallowing alendronate with little or no water, lying down during or after ingestion of the tablet, lying down during or after ingestion of the tablet, continuing to take alendronate after the onset of symptoms, and having preexisting esophageal disorders. CONCLUSIONS: Alendronate can cause chemical esophagitis, including severe ulcerations, in some patients. Recommendations to reduce the risk of esophagitis include swallowing alendronate with 180 to 240 ml (6 to 8 oz) of water on arising in the morning, remaining upright for at least 30 minutes after swallowing the tablet and until the first food of the day has been ingested, and discontinuing the drug promptly if esophageal symptoms develop.

Aged↗
PubMed1993

Deficiencies in the National Institute of Health's guidelines for the care and protection of laboratory animals.

This paper is a critique of NIH guidelines for the care and protection of laboratory animals. It exposes four serious deficiencies in these guidelines: (1) failure to make it clear that the mere pursuit of knowledge does not justify using animals; (2) failure to give any guidance concerning what constitutes human benefit or well-being; (3) failure to countenance trade-offs between human benefit or well-being and animal well-being; (4) failure to clearly specify what constitutes keeping animals in an 'environment appropriate to the species and its life history.' It concludes with the suggestion that the construction and revision of these guidelines is too important to be left to the professionals.

Animal Care Committees↗
PubMed1986

In vivo survival of red blood cells processed by a bubble or membrane oxygenator during cardiopulmonary bypass surgery.

A dual radioisotope labeling technique was utilized to assess red cell survival differences between cells processed by either a bubble oxygenator (eight patients) or membrane oxygenator (eight patients) in 16 patients undergoing cardiopulmonary bypass surgery. Cells processed by a bubble oxygenator consistently had a shortened survival. The 30-minute recovery of cells was not significantly different between oxygenators in contradiction to some previous studies using plasma hemoglobin as an indicator of hemolysis. The results of this investigation confirm previous studies that a membrane oxygenator provides a survival advantage to red cells during cardiopulmonary bypass surgery.

Journal Article↗