Citations

Abstract In an age- and sex-stratified population sample (n = 700), we estimated fall-related loads and bone strength indices at the UDR and FN. These load/strength ratios more closely simulated patterns of wrist and hip fractures occurring in the same population than did measurement of vBMD. Introduction: Areal BMD measurements, although associated with fracture risk, incompletely explain patterns of fragility fractures. Moreover, population-based assessments relating applied loads and whole bone strength to fracture patterns have not been made. Materials and Methods: Using QCT, we assessed volumetric BMD (vBMD), cross-sectional geometry, and axial (EA) and flexural (EI) rigidities (indices of bone's resistance to compressive and bending loads, respectively) at the ultradistal radius (UDR) and femoral neck (FN) and estimated the loads applied to the wrist and hip during a fall. We used fall load (FL)/bone strength ratios to estimate fracture risk. Results: vBMD in young adults was similar between sexes. Decreases in vBMD over life were also similar (30% and 28%) at UDR but were somewhat greater (46% and 34%) at FN in women versus men, respectively. In young adults, FL/strength ratios at UDR were 32–51% lower (better) in men than in women and increased (worsened) over life less in men (+4% to +22%) than in women (+20% to +33%). In young adults, FL/strength ratios at FN were only marginally better in men than in women but worsened less over life in men (+22% to +36%) than in women (+40% to +62%). Conclusions: The 6:1 female preponderance and the virtual immunity of men for age-related increases in wrist fractures are largely explained by the more favorable FL/strength ratios at UDR in young adult men (because of larger bone size and more favorable geometry) versus women and to maintaining this advantage over life. The 2-fold lower incidence of hip fractures in men versus women is largely explained by age-related increases (worsening) of FL/bone strength ratios that are only one-half of the increases in women. The moderate increases in these ratios with aging are insufficient to explain the >4-fold increase in hip fracture incidence after age 75 in both sexes, suggesting contributions of other factors, especially the well-documented increased frequency of injurious falls among the elderly.

AbstractIdentification of multiple clinical and pathologic prognostic factors in differentiated thyroid cancer has permitted some degree of risk stratification. However, these clinical indices fail to distinguish potential intrinsic differences in tumor virulence. The nm23 gene has been identified as a potential metastasis suppressor gene that is homologous to nucleoside diphosphate kinases. Studies in human breast cancer have shown a significant inverse correlation between nm23 levels and nodal involvement/tumor recurrence. Given the possible clinical utility of a marker of metastatic potential in the management of thyroid carcinoma, we examined 34 thyroid neoplasms and a human medullary thyroid cancer (MTC) cell line (TT) for nm23 expression. Normalized nm23 expression was assessed by Northern analysis of tumor RNA. nm23 Expression (tumor expression/TT cell expression, mean ±SE) was 1.14 ±0.15* in MTCs (n =5), 0.70 ±0.10* in follicular cancers (n=6), 0.51 ±0.11 in papillary cancers (n=19), and 0.31 ±0.03 in follicular adenomas (n=4) (*p< 0.05 when compared to adenomas). Within histologicgroups, we found no correlation between nm23 expression and nodal involvement or distant métastases. Our results indicate that thyroid neoplasms of different histologies express varying levels of the nm23 transcript. Although nm23 expression seems diminished in metastatic breast cancer, it appears not to be the case in metastatic thyroid cancer. The nm23 gene may therefore have different roles in the evolution and metastases of different neoplasms.