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R Lazenby

Publications and source records attributed to R Lazenby.

4 recordsLinked to original sources

Brief communication: cortical remodeling data are affected by sampling location.

It has been argued that techniques for estimating adult age-at-death from cortical histology are deleteriously affected by sampling location. This study uses nine complete femoral midshaft cross-sections to test the effect of sampling site on measurement of a standard histological variable, percent remodeled bone. Circumferential periosteal fields from four anatomically defined locations (anterior, posterior, medial, lateral) and four mechanically defined locations (maximum and minimum moments of area) were evaluated. Locations deviating from the periosteal surface toward the endosteal surface were also compared. Significant differences were found for both location and field placement. The anatomical axes exhibited greater variability than the mechanical axes, in particular the anterior location, a standard sampling site for age-at-death estimation techniques. More endosteal fields tended to show elevated levels of percent remodeled bone. This study demonstrates that circumferential and radial sampling locations are important considerations in deriving and applying predictive equations based on cortical remodeling.

Adult↗

Brief communication: non-circular geometry and radiogrammetry of the second metacarpal.

Traditional radiogrammetry of the second metacarpal midshaft reconstructs cortical cross-sectional geometry from mediolateral (ML) linear dimensions based on circular model. However, comparison of anteroposterior (AP) versus mediolateral radiographic dimensions in a sample of paired metacarpals shows that AP total and medullary widths typically exceed ML widths by 5% to 10%. As well, in 13% of males and 25% of females, the two metacarpals are dissimilarly shaped, i.e., the AP/ML ratio is > 1.0 for one side and < 1.0 for the other. This situation exaggerates the differences in geometric properties between sides and constitutes a potentially significant source of bias for analyses of bilateral asymmetry. These results suggest that the circular model is inappropriate for estimation of cross-sectional geometry at this anatomical location.

Adult↗

A collaborative effort for rural health.

Collaboration between the W.K. Kellogg Foundation and a school of nursing helped to meet health care and environmental needs of the residents in two rural counties burdened with poverty and illiteracy. This endeavor also affords the faculty and students in the school of nursing opportunities to work with underserved populations in rural areas. The project continues its community service through evolving programs.

Educational Status↗

Porosity-geometry interaction in the conservation of bone strength.

Automated image analysis of a small sample of femoral cross-section radiographs has revealed a consistent difference in bone porosity relative to geometry. Two sub-periosteal fields were assessed microscopically, with field location determined with reference to the principal moment axes (Imax, Imin). The data indicate that: (1) porosity is greatest in the direction of maximum geometric resistance to bending, along the Imin axis; and (2) porosity differences between the Imax and Imin fields decrease as the bone becomes more circular in cross-sectional shape.

Adult↗