Junctional epidermolysis bullosa keratinocytes in culture display adhesive, structural, and functional abnormalities.

An unusual, elongated, refractile cell morphology was observed in keratinocytes cultured from three patients with non-lethalis forms of junctional epidermolysis bullosa (JEB). To determine whether these changes might be related to altered cell adhesion, keratinocyte strains established from one patient were examined for adhesive, structural, and functional characteristics. JEB keratinocytes expressed keratin tonofilaments, as determined by staining with AE1 monoclonal antibodies and direct observation of tonofilaments by electron microscopy. JEB keratinocytes showed diminished cell-substratum adhesions, judged by interference reflection microscopy. Areas of diminished cell-substratum adhesion corresponded to F-actin-rich cell adhesions (focal adhesions) and not to cellular areas that abundantly express hemidesmosomal antigens. Analysis of cell-substratum adhesion by electron microscopy revealed extensive areas of cell-substratum separation in JEB keratinocytes that were not present in normal keratinocytes maintained in serum-free medium. Normal keratinocytes displayed numerous regions of focal contact between the ventral plasma membrane and the culture substratum, but these structures were not seen in JEB keratinocytes. Bundled actin filaments (stress fibers) were greatly diminished in expected regions of cell-substratum adhesion in JEB keratinocytes and, instead, displayed disorganized individual filaments. The growth rate of JEB keratinocytes was quite slow in culture, with a population doubling time of 2.7 d versus 1.5 d for normal keratinocytes under identical conditions. JEB keratinocytes also displayed a reduced ability to aggregate into colonies upon exposure to medium with increased extracellular calcium. JEB keratinocytes thus display adhesive, structural, and functional abnormalities that suggest this cell type may be central to the pathogenesis of junctional epidermolysis bullosa. Study of affected keratinocytes could be important to characterize associated molecular pathologies.     

Warping of cross sections in the torsion of long bones with internal fracture fixation plates

Torsion of noncircular beams results in warping of each cross section. When noncircular cross sections are constrained to remain plane, the resulting shear stress distribution is different from what Saint Venant torsion (with warping) would predict. This has practical implications to the stress analysis of plated long bones subjected to torsional loadings. Analyses in which warping is not allowed predict incorrect stress fields in the plate and bone and overpredict the amount of stress shielding associated with fracture plate fixation.     

Trends in Folic Acid Awareness and Behavior in the United States: The Gallup Organization for the March of Dimes Foundation Surveys, 1995–2005

Objective: To summarize changes in folic acid awareness, knowledge, and behavior among women of childbearing age in the United States since the U.S. Public Health Service (USPHS) 1992 folic acid recommendation and later fortification. Methods: Random-digit dialed telephone surveys were conducted of approximately 2000 women (per survey year) aged 18–45 years from 1995–2005 in the United States. Results: The percentage of women reporting having heard or read about folic acid steadily increased from 52% in 1995 to 84% in 2005. Of all women surveyed in 2005, 19% knew folic acid prevented birth defects, an increase from 4% in 1995. The proportion of women who reported learning about folic acid from health care providers increased from 13% in 1995 to 26% in 2005. The proportion of all women who reported taking a vitamin supplement containing folic acid increased slightly from 28% in 1995 to 33% in 2005. Among women who were not pregnant at the time of the survey in 2005, 31% reported taking a vitamin containing folic acid daily compared with 25% in 1995. Conclusions: The percentage of women taking folic acid daily has increased modestly since 1995. Despite this increase, the data show that the majority of women of childbearing age still do not take a vitamin containing folic acid daily. Health care providers and maternal child health professionals must continue to promote preconceptional health among all women of childbearing age, and encourage them to take a vitamin containing folic acid daily.