Age-related changes in cancellous bone structure. A two-dimensional study in the transiliac and iliac crest biopsy sites.

In 94 pairs of large sections of normal iliac bone (53 men, 41 women, aged 20-80 years) we confirmed trabecular bone area (B.Ar) and the mean number of trabeculae per mm (Tb.N) to decline with age, in areas representative of the transiliac (TI) and iliac crest (IC) biopsy in both sexes, whereas mean trabecular width (Tb.Wi) did not decrease. Our data also confirm that disappearance of entire elements is the main event in age-related loss of trabecular bone. In addition, our study demonstrated that Tb.Wi is lower in women than in men in the IC site, and a preferential loss of the thinner trabeculae could be seen in this group. Up to 50 years, Tb.N was found higher in women in both sites. B.Ar and Tb.Wi values are markedly higher in the TI site (+/- 15%); Tb.N values were similar. Measured and calculated Tb.Wi values show systematic differences. In a pilot study in 14 IC biopsies with widely diverging B.Ar values, we tested the validity of several equations currently used for derived parameters in the structural analysis of cancellous bone sections. The equation for mean trabecular number passed the test, whereas the validity of the equations for mean trabecular separation and Tb.Wi appeared limited. We found anisotropy of iliac bone to increase as B.Ar decreases.

Microdensitometric analysis of bone structures in X-ray images.

The careful evaluation of bony structure is important in the study of normal bone and bone disorders. This study describes bony structure as seen in the X-ray pattern of the phalanges of the hand using quantitative microdensitometry. Normalised scans of bony density show the regular and irregular distribution of the trabeculae. Two properties were determined from these densitometric findings: the mean transverse coarseness (C) indicating fluctuations of horizontal density and the overall standard deviation indicating axial homogeneity (H). This investigation demonstrates the applicability of the method: it shows a significant correlation with radiological diagnosis and that microdensitometry is a reliable method for quantifying the coarseness and homogeneity of bone structure.

Software for bone histomorphometry by means of a digitizer.

A set of programs is described by which a consistent morphometry of bone sections can be performed. The programs are written in FORTRAN IV in a PDP 11/10 minicomputer, under the RT-11 operating system. The bone sections are run through the field of vision of the microscope using a scanning stage in one of several preselected courses at a magnification suitable for the parameters that are being put in. When input is completed, a print-out is produced with measured and derived parameters, personal data (protected by a code) and a comment file, all of which are stored for later retrieval and statistical evaluation. The programs were developed to be used in a system in which the bone sections are projected (by a projection microscope) onto a digitizer connected to the computer.

Shifts of delayed immune response to persulphates and other allergens.

Certain chemicals such as persulphates and formaldehyde are able to induce both immediate and delayed type reactions in the skin. The levels of delayed type response to persulphates (at 48 and 74 h), obtained by epicutaneous tests were subjected to comparative studies of shifts (48 versus 72 h) and statistical analysis. The 95% confidence limit of the mean value of shifts to persulphates was significantly higher than that of a standard routine battery as a whole and, with the exception of formaldehyde, also to that of other individual constituents of this battery. In the case of persulphates, this difference in shifts was due to an extremely low mean value of delayed-type response read at 48 h. The possible underlying mechanisms and the possible limiting rôle of vaso-active amines in the early evolution of delayed-type response is discussed.