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Biomedical subjects

R Rudman

Publications and source records attributed to R Rudman.

4 recordsLinked to original sources
PubMed1999

Trauma modifies strength and composition of retrodiscal tissues of the goat temporomandibular joint.

OBJECTIVES: Temporomandibular pain is often accompanied by pathologic changes to joint retrodiscal tissues. The substantial representation of females in this condition has encouraged hypotheses which link genetic or hormonally induced abnormalities in tissue composition (type III collagen, type I collagen, type III/type I ratio) to the development of temporomandibular disorders. As this condition is often associated with a history of orofacial trauma, we investigated the functional impact of retrodiscal trauma on the composition and biomechanics of retrodiscal tissues. DESIGN AND METHODS: Retrodiscal tissue of female goats received trauma or sham trauma. Following a healing period of 30 days, the tissues were pulled to failure on an extensometer. OUTCOME MEASURES: Assessments were made of tissue biomechanical properties (failure force, elastic stiffness, strain distribution). Tissue fragments were assayed for collagens I and III. RESULTS: Thirty days after surgical section of retrodiscal tissues, the tissue had reformed, but the composition and biomechanics were substantially changed. Healed tissue manifested less than half the strength of normal tissue (P = 0.02). In addition, the development of tissue strain shifted from a relatively even distribution to a confined region near the retrodiscal-discal attachment zone. It appeared that a large increase in the expression of type III collagen (179.6%; P = 0.038) and the ratio of type III/type I collagen (180.9%; P = 0.011) accounted for these functional changes. CONCLUSIONS: We suggest that shifts in collagen expression following injury create shifts in strain development which focus tissue stresses near the interface of the disc and retrodiscal tissue, and that this shift dramatically weakens the tissue and increases the probability of re-injury, inflammation and pain.

Animals↗
PubMed1991

The body condition of feral ponies on Assateague Island.

The summer body condition of 47 adult feral ponies on Assateague Island (off the coast of Maryland, USA) was assessed in June 1988 using a visual body condition scoring system. Winter body condition for 36 of the ponies was assessed in February and March, 1989. The ponies were categorised by gender, reproductive status and location on the island, and body condition scores of the ponies in each category were then compared by statistical analyses. No significant seasonal differences were found in the body conditions of the ponies. However, body condition of stallions was better than that of mares. Also, lactating mares had lower body condition scores than non-lactating mares. Finally, in the summer, ponies on the southern part of the island were in better condition than those on the northern end where food and other resources were more limited. Thus gender, reproductive status and habitat, according to the criteria of this study, all had an effect on the body condition of Assateague Island feral ponies, whereas seasonal effects were not evident. Future studies could clarify the correlation between the condition of the mares during the breeding season and birth rate and survival of foals the following spring.

Animals↗
PubMed1978

The structure of crystalline tris: a plastic crystal precursor, buffer, and acetylcholine attenuator.

The crystal and molecular structure of the widely used buffer tris(hydroxymethyl)aminomethane (tris) has been determined from single-crystal diffractometer data to a standard agreement factor (R value) of 0.026 and bond length standard deviations of 0.002 angstrom. Tris crystallizes in the orthorhombic system, space group Pn21a, with four molecules per unit cell; a = 8.844(1) angstroms, b = 7.794(1) angstroms, and c = 8.795(1) angstroms. The center-to-center distances of tris molecules in the ordered phase range from 0.4 to 1.0 angstrom less than they do in the orientationally disordered (plastic) phase of similar molecules.

Acetylcholine↗