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Biomedical subjects

D L Berens

Publications and source records attributed to D L Berens.

9 recordsLinked to original sources
PubMed1990

Morphometry of the lumbar spine: anatomical perspectives related to transpedicular fixation.

The pedicles of lumbar vertebrae were measured both directly and radiographically to determine the differences between the sexes and the accuracy of radiographic measurement. The lumbar pedicles of cadavera of forty-nine patients--twenty-four men and twenty-five women--who died between the ages of sixty and ninety-eight years were measured directly and on radiographs. The pedicles of lumbar vertebrae from fifty-one patients--twenty-three men and twenty-eight women--between the ages of twenty and fifty years who had low-back problems were measured on radiographs and computerized tomographic scans. Comparison revealed that the average transverse and sagittal diameters of the pedicles and the distance from the posterior aspect of the laminar cortex to the anterior aspect of the cortex of the vertebral body along the central axis of the pedicles were 5 to 20 per cent greater in men, but the transverse and sagittal angles of the pedicle did not differ significantly between the sexes. Measurements on radiographs and computerized tomographic scans of the transverse angles of the pedicles and of the distances from the posterior aspect of the laminar cortex to the anterior aspect of the cortex of the vertebral body from the second to the fifth lumbar vertebra were greater than direct measurements, even without magnification. Direct measurements of the diameters of the transverse and sagittal diameters of the pedicle of the fifth lumbar vertebra, however, were greater than the radiographic measurements.

Adult↗
PubMed1985

An effective surrogate for impact studies.

Nineteen unembalmed (fresh) cadavers were used in 21 experiments to test restraint systems in automobile impact studies. Some were mounted in a rearward firing sled; others were placed in standard cars during collisions. Prior to and after testing, each cadaver was evaluated. After each experiment a postmortem examination was performed. High-speed registering cameras (1,000 to 2,000 frames per second) were used and multiple telemetric recordings were made. The radiographic and pathologic changes were similar to those seen in patients following high-velocity accidents. Results were compared with those of car accident victims admitted dead on arrival to one of our hospitals. This study is a progress report. The results are being used to improve existing restraint systems and to evaluate experimental models.

Accidents, Traffic↗
PubMed1975

Experimental studies on osteoporosis.

Nutritional secondary hyperparathyroidism (NSH) defines a spontaneous and experimental disease in most domesticated and in some wild animals, caused by dietary calcium deficiency and/or phosphorus excess. Calcium deficiency results directly in hypocalcemia, and phosphorus excess induces hyperphosphatemia which causes hypocalcemia. Secondary hyperparathyroidism thus results and the plasma parameters return to normal and are maintained but only at the expense of progressive bone loss. The bone loss is generalized but the bones are not uniformly affected. The hierarchy of bone loss is, in decreasing order, the jaw bones, especially the alveolar bone, other skull bones, ribs, vertebrae and, finally, long bones. Osteocytic osteolysis is the main mechanism of resorption and application of this concept is a condition sine qua non in the interpretation of the histologic lesions. The early loss of alveolar bone constitutes the initial event in periodontal disease in animals. The osseous lesions in animal NSH are reversible by correction of dietary calcium and phosphorus levels, provided a hyperostotic osteodystrophia fibrosa has not yet developed. The applicability of animal NSH as a model for human osteopenic conditions, including periodontal disease and spinal osteoporosis, is supported by the very inadequate calcium and phosphorus nutrition in most Western countries. The diet is deficient in calcium and excessive in phosphorus; both conditions induce NSH in animals. The degree of dietary calcium deficiency, as influenced by geographic, economic, and social factors, is positively correlated to the degree of periodontal disease and osteoporosis in the population. Evidence is presented to show that the radiographic and histologic manifestations of human periodontal disease and osteoporosis are the same as those of animal NSH. Periodontal disease is therefore considered a fore-runner to the clinically more important spinal osteoporosis. Limited experiments in human periodontal disease indicate that added dietary calcium can positively influence the alveolar bone loss.

Adolescent↗