Biomedical subjects

R Beaver

Publications and source records attributed to R Beaver.

12 recordsLinked to original sources

PubMed2001

The development and mature organisation of the end-artery retinal vasculature in a marsupial, the dunnart Sminthopsis crassicaudata.

The end-artery retinal vasculature of a marsupial, the fat-tailed dunnart, was defined by India ink injection and studied in wholemounts. In the adult, the vitreal vasculature supplying the ganglion-cell layer has major paired-vessels in a horizontal H shape. These vessels skirt the area centralis and visual streak that are supplied by fine end-loops. A second vascular layer of uniformly distributed endloops arises from the superficial vessels and lies at the inner nuclear/outer plexiform border. During development, vessels enter the eye via the optic nerve head to form the upper vasculature, assuming an essentially mature arrangement prior to the formation of the area centralis and visual streak. Vessels then descend to form the lower bed. Unlike the cat, the dunnart has retinal vessels that are patent throughout development, their growth is interstitial and reductive remodelling is not seen. A retinal end-artery system may have evolved in marsupials because their precocity requires a vasculature that is functional from early stages of development.

Animals↗

PubMed1998

Patient self-assessment of tibial plateau fractures in 40 older adults.

This retrospective study examined the outcome of 40 patients 50 or more years of age treated between September 1988 and September 1993 for tibial plateau fractures. Our analysis was based on a review of the medical records of all patients as well a patient self-assessment questionnaire. The 22 women and 18 men studied had a mean age of 60 (range, 50 to 76 years) at the time of injury. A satisfactory overall outcome (based on patients' self-assessment) was observed in only 14 (35%) of the 40 cases. Unsatisfactory outcomes were observed in 23 (72%) of 32 cases treated operatively and 3 (38%) of 8 cases treated nonoperatively. No significant difference in outcome was observed between the 27 patients with AO type B fractures and the 13 patients with AO type C fractures. Similarly, no significant difference in outcome was observed in patients with fractures involving the lateral plateau only, those with fractures involving the medial plateau only, and those with bicondylar fractures. There was no significant relationship between the adequacy of fracture reduction and overall clinical outcome, although a trend of more favorable outcomes was noted in patients with excellent or satisfactory reductions. The results suggest that patients of 50 or more years of age have a high rate of unsatisfactory clinical outcomes regardless of how their tibial plateau fractures are treated.

Age Factors↗

PubMed1997

An analysis of the actual cost of tibial nonunions.

The financial and medical records of 11 patients diagnosed with a tibial nonunion were evaluated in order to assess the costs associated with the care of this clinical entity. The initial tibia fractures were seen at Hermann Hospital (Houston, Texas) between April 1991 and June 1993. We included only those patients who had a diagnosis of tibial shaft nonunion which we defined as a tibial fracture which was without radiographic or clinical evidence of progressive healing 6 months after the initial injury. A total of 9 patients were available for evaluation and 2 were lost to follow-up.

Adolescent↗

PubMed1993

Penetration and shear strength of cement-bone interfaces in vivo.

Using sham replacement of the proximal femur in adult mongrel dogs, shear strength at the interface between polymethylmethacrylate bone cement and cancellous bone has been found to be linearly dependent on the depth of penetration of the cement into the bone. Shear strength at the interface was increased by 82% and penetration by 74% when distal bone plugging, pressure lavage, and pressurized insertion of cement were employed. Use of a lower-viscosity cement gave a further 18% increase in penetration and shear strength. There was no film of blood at the cement-bone interface with pressurized insertion of Simplex P and Palacos R cements.

Acrylic Resins↗

PubMed1989

Intermittent parasympathetic symptoms in lumbar spinal stenosis.

Symptoms related to autonomic nervous dysfunction are uncommon in spinal stenosis. Involvement of nerve roots S2-S5 has previously been reported only in a few cases. Of great interest is the occurrence of phenomena such as intermittent penile erections and fecal incontinence on walking in patients with compromise of the lower lumbar spinal canal. We report on two patients, one of whom presented because of fecal incontinence and the other with penile erections on walking. In both cases, these manifestations resolved after decompressive laminectomy. These patients are compared to six other patients, with parasympathetic disturbances due to lumbar spinal stenosis, described previously.

Fecal Incontinence↗

PubMed1986