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Biomedical subjects

R S Riggins

Publications and source records attributed to R S Riggins.

At least 19 recordsLinked to original sources
PubMed1987

Influence of internal fixation on wound infections.

With increasing frequency trauma surgeons are advocating early internal fixation in open fractures. The effect of the fixation devices on the infection rate in contaminated wounds remains a concern as our clinical experience in this area has been mixed. To study the effects of internal fixation on bone infections a 3.5-mm stainless steel screw was inserted into rabbit femurs and the wounds contaminated with Staphylococcus aureus. The controls had the screw hole drilled and taped but the screw was not inserted. Thirty of 49 rabbits receiving the screw subsequently became infected whereas 19 of 56 control animals developed an infection. The difference was significant at the 0.05 confidence level.

Animals↗
PubMed1985

Weight bearing: its lack of effect on fracture healing.

The load transmitted through fresh fractures of the tarsometatarsus of adult chickens was varied by 40% more, or less, than the body weight to determine the effect of load-bearing on fracture healing. The healing fracture was examined for size and strength at 14 days, but no significant differences were detected in any group. The technique was sensitive enough to detect the differences between healing fractures at 7, 10 and 14 days. In this experiment load transmission was not found to be an important factor in fracture healing.

Animals↗
PubMed1983

Mechanical properties of the tibia from chickens with idiopathic scoliosis.

The tibia from six-week old chickens that develop idiopathic scoliosis were studied with stress relaxation experiments and torsional strength testing. Most parameters observed did not show any significant differences between tibias obtained from chickens with scoliosis and tibias from the control birds; however, the rate of stress relaxation of the tibia from the birds with scoliosis was minimally increased over the controls. There were no significant differences noted in ultimate torsional strength, maximum angular deformity or modulae of torsional rigidity of the tibias from scoliotic chickens when compared to tibias from control chickens.

Animals↗
PubMed1983

Treatment of open fractures: a prospective study.

A double-blind prospective study was done to assess the benefit of delaying closure of the wounds associated with open fractures. An additional double-blind study compared the effectiveness of clindamycin versus cefazolin for prophylactic antibiotic coverage. Quantitative cultures of the wounds were accomplished at the time of debridement and again at the time of closure if the wound was not closed initially. Almost half of the wounds were contaminated (46%) at the time of debridement, although the incidence of wound infection was low (6.5%). Gram-negative organisms resistant to the prophylactic antibiotic were recovered initially only eight times, but four of these (50%) became infected. The contaminating organisms in each case were present in high concentration (greater than 10(5) CFU/gm of tissue) at initial culture. The time of wound closure, cefazolin versus clindamycin, and internal fixation of the fracture were not followed by significant differences in the development of clinical infection in this series.

Adult↗
PubMed1983

Hip dislocations in myelodysplasia: a functional assessment.

We reviewed the records of 281 patients with myelodysplasia to ascertain the effect of hip dislocation on their ability to walk. There was no difference in the prevalence of myelodysplasia by gender. When adjusted for neurologic level and patient age, no statistical differences were found in the methods of locomotion between patients with hip dislocations and those without. Data (from this report and other published investigations) show that treatment for hip dislocation in myelodysplasia is unnecessary and fraught with many complications.

Adult↗
PubMed1982

Role of copper in collagen cross-linking and its influence on selected mechanical properties of chick bone and tendon.

Day-old White Leghorn cockerels were fed skim-milk-based diets containing 0, 2, 4, 8, or 16 ppm added copper as CuSO4 for 21 days. Lysyl oxidase was extracted from bone and tendon. The recovery of activity from the extracts was linearly correlated with dietary copper (r greater than 0.90). Tests of the mechanical properties of tendon and bone indicated that tendon viscoelasticity (as measured by stress--relaxation) may not be significantly influenced by copper, whereas the ultimate torsional strength of bone is markedly decreased when the dietary copper level is below 1 ppm. Furthermore the torsional fracture characteristics of bone from copper-deficient birds demonstrated a lack of plastic deformation prior to failure that was normally seen in bone from control birds. The change in the mechanical properties of bone from copper-deficient birds appeared to be related to a decrease in the amounts of dihydroxylysinonorleucine and other lysine-derived cross-linking amino acids in bone collagen. The data indicate that the requirement for optimal growth of chicks fed skim-milk-based diets is 6--8 ppm copper, however, the requirement for normal cross-link formation in bone is less than 2 ppm copper.

Amino Acid Oxidoreductases↗
PubMed1982

Structural properties of Type I collagen isolated from chickens with scoliosis.

This study examines biochemically the Type I collagen isolated from skin of chickens that develop idiopathic scoliosis. Previous studies indicate a defect in collagen exists in these chickens. Alpha 1 (I) and alpha 2 chains were separated by gel filtration and carboxymethyl cellulose column chromatography and were then subjected to the analytical techniques of sodium dodecyl sulfate gel electrophoresis, Staphylococcus aureus V8 protease digestion, cyanogen bromide peptide mapping and amino acid analyses. In all categories, the scoliotic alpha 1 (I) and alpha 2 chains were identical to alpha chains isolated from normal chickens. These data suggest that the altered properties of collagen solubility and connective tissue stress relaxation seen in these scoliotic chickens are not a manifestation of an altered primary structure of the alpha chains or post-translational modification affecting chromatographic elution profiles or electrophoretic migration patterns.

Amino Acids↗
PubMed1978

Quantitative microbiology of traumatic orthopedic wounds.

Quantitative bacterial and fungal cultures carried out on 116 speciments of tissue debrided from traumatic orthopedic wounds yielded 118 bacterial and 8 fungal isolates. The organisms obtained reflected primarily the resident flora of the skin.

Aerobiosis↗
PubMed1977

Nutritional copper deficiency and penicillamine administration: some effects on bone collagen and arterial elastin crosslinking.

Nutritional copper deficiency effects marked changes in the crosslinking of collagen and elastin, presumably in relationship to copper's role as a cofactor for lysyl oxidase. Lysyl oxidase controls one of the initial steps in the crosslinking of elastin and collagen, i.e., the conversion of peptidyl lysine or hydroxylysine residues to peptidyl alpha-aminoadipic-delta-semialdehyde derivatives. Once lysine-derived aldehydic functions in collagen and elastin are formed, crosslinks occur via aldol and Schiff-base type condensations. A decrease in the degree of crosslinking results in changes in the biomechanical properties of both collagen- and elastin-rich tissues. Some of these changes are described with respect to chick bone and aorta. Likewise, penicillamine blocks crosslinking reactions. In this case, however, it is probably because of the formation of thiazolidine complexes between penicillamine aldehydic functions. The administration of penicillamine at different levels to young growing chicks allows the isolation of fibrous insoluble elastin varying in aldehyde content.

Amino Acids↗
PubMed1977

Effect of ethane-1-hydroxy-1,1-diphosphonate (EHDP) and dietary fluoride on biomechanical and morphological changes in chick bones.

There are only a few papers in the literature in which parameters related to bone strength are examined over wide range of fluoride concentrations. In this report, chicks were used and fed diets containing fluoride added at 0, 50, 200, or 800 ppm in preparation for measurements on bone strength. The diets were fed for 20 days. After 10 days, the birds were also injected daily with solutions containing either isotonic saline or 5 mg of ethane-1-hydroxy-1,1-diphosphonate (EHDP) as phosphorus/kg body weight or 10 mg of EHDP as phosphorus/kg body weight. The effects of added fluoride and EHDP on bone morphology and the biomechanical properties of bone were then examined. The rate of bone formation was assessed using histological and tetracycline labeling techniques. Administration of high fluoride and/or EHDP resulted in significant changes in bone morphology. The changes effected by the administration of EHDP appeared independent of fluoride induced changes. Biomechanical studies also indicated that both high levels of fluoride and EHDP caused a significant reduction in bone torsional breaking strength. The reductions in breaking strength were independent of changes in body size.

Animals↗
PubMed1977

The risk of neurologic damage with fractures of the vertebrae.

The incidence of spinal cord injury with spine fractures and dislocations is approximately 14% of the total as ascertained from a survey of these injuries in Northern California, and 17% of traumatic spinal cord injuries gave no overt radiographic evidence of vertebral injury. Patients sustaining fractures of the vertebral bodies and posterior elements with some degree of malalignment of the spine had a 61% incidence of neurologic deficit. Injuries to the cervical spine most often produced neurologic damage, the incidence of neurologic deficit being 39%. Motor vehicle collisons continue to be the major cause of these injuries and the victim is usually a young adult male.

Acute Disease↗
PubMed1977

The effect of increased gravitational stress on bone.

To assess the effects of an altered gravitational state on the physical properties of bone, fifteen sexually mature chickens were centrifuged for 18 weeks. The gravitational forces were gradually increased to allow the chickens to adapt to the increased load. For the last 4 weeks of the experiment, the animals were subjected to a force of 3 x gravity. After sacrifice the tibias were removed and fractured in torsion. Bone diameters, cortical thickness and ash content of the tibias were determined. Histological preparations of the bone specimens were also examined. When the centrifuged animals were compared with control chickens of comparable size and weight, there was no significant change in bone strength or fracture pattern, although the centrifuged birds had smaller mid-tibial shaft diameters and thicker cortices. The mean percentage bone ash for the centrifuged birds was 68.2% which is an accepted value for dry bone ash of adult chickens. Bone density was the same for both centrifuged and control birds. The birds lost an average of 465 grams of body mass during their 18 weeks on a centrifuge.

Adaptation, Physiological↗