The excretion of collagen cross-links in malnourished children and their subsequent recovery - abstract

Pyridinoline (PYD) and deoxypridinoline (DYP) molecules cross-link the collagen in bone and cartilage. They are neither re-used in the body nor found in the collagen of any other organ. We have measured the urinary excretion rate of these cross-links in 46 severely malnourished boys to assess their skeletal turnover and to relate the output to the subsequent rate of growth in height. The children were 12 +/- 6mo, -3.6 +/- 1.6 SD units height-for-age and -2.4 +/- 0.9 SD units weight for height. Their excretion when malnourished and after recovery was 11.4 +/- 5.3 (mal, X +/- DS) and 32.3 +/- 10.8 (rec) of PYD and, 2.7 +/- 1.5 (mal) and 7.5 +/- 3.0 (rec) of DYP (all nmol .h-1 .m-ý). This indicates that skeletal turnover is much less in the malnourished than the recovered child. Comparison with Italian control data indicates that there is depressed skeletal metabolism in malnutrition. There was a significant relationship between the cross-link excretion, age and weight-for-height and the rate of height gain in the subsequent month by multiple regression analysis. These three factors - age, degree of wasting amd skeletal turnover accounted for 44 percent of the variance in the subsequent height velocity of the children. It may be possible to use PYD and DYP to assess therapeutic intervention designed to alleviate stunting(AU)

Delayed skeletal maturation in sickle cell anemia in Jamaica

The maturation of the left distal radial epiphysis was studied in 86 adolescent patients with homozygous sickle cell disease in Jamaica. Development was retarded in 81 patients and in the remaining five, the epiphysis had fused. Delay in epiphyseal fusion related to the level of fetal haemoglobin. Delay in epiphyseal fusion may be an important determinant of the characteristic habitus of adults with sickle cell anemia.(Summary)

Alizarin red in the study of the apposition and resorption of bone

Alizarin red is given intraperitoneally in dosages of 50-200 mg per kg. It stains visibly only one generation of bone. Its deposition is studied in gross specimens and in undecalcified sections, and is controlled by comparison with serial decalcified sections. Apposition of white bone can be followed in relation to red bone on periosteal surfaces (where it presents appearances corresponding to different growth rates), on endosteal surfaces, in osteons, and in the interstitial compaction of cancellous bone. Red surfaces may be sites of deposition, stasis, or resorption. Measurements may be made from red lines, provided microscopic control is available. Removal of red bone implies resorption. It is closely correlated with the presence of osteoclaasts in control sections and with areas of surface pitting grossly. Resorbing surfaces may be precicely delimited by studing a graded series of animals. Whole surfaces or zones of stained bone are seen to drift to other situations, undergoing resorptive dissolution or consolidating anew as they move relative to the newer layers. The usefullness of the dye lies in its simplicity of administration, its ready visibility, and the fact that its persistence in bone enables the fate of areas of bone to be followed over long periods. The preparation of undecalcified sections is a problem common to many other techniques

Adaptive development and structure in the radius of the odontocete

Radii of the smaller toothed-whales are striking examples, developmentally and structurally, of accommodation to the requirements for secondary marine adaptation. This was studied, with cleared whole mounts and histological sections from the fetus and with radiographs of adult bones, in the beluga (Delphinapterus leucas) and pilot whales (Globicephala melaena). Radii are flattened, semistreamline in cross-section and, like the ulnae, articulate (synchondrosis) end-on with the humerus. Distal to the elbow, the flipper is amuscular. Radial development is characterized by a high ratio of transverse to longitudinal growth rates, by a slow, irregular process of endochondral ossification, by retention of endochondral spicules in lieu of a medullary cavity, and by a deep deposit of variably spongy periosteal bone. Ultimately, the radius has medial and lateral concentrations of bone a lesser central density mimetic of a mechanically advantageous box-beam. Throughout life, however, the history of the bone is revealed by proximal and distal endochondral cones and surrounding masses of periosteal bone, distinguishable in lateral radiographs. From this geometry, and from cross-sections, it is clear that the radius grows eccentrically, i.e., circumferential increments to epiphyseal plates, and to periosteal surface, are greatest on the posterior margin, intermediate along medial and lateral sides and least on the anterior margin. In the ulna, growth is in the opposite sense. Opposite margins of the elongating antibrachial bones thus move apart while adjacent margins hold relatively the same positions. Eccentric growth maintains the ratio of major to minor axes in the cross-section. The Arctic beluga radius is more dense, and radiographs reveal within it the outline of the neonatal radius. Beyond this outline, variable porosity suggests periodic growth (AU)