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EXPERIMENTAL LATHYRISM. AN AUTORADIOGRAPHIC STUDY.

In normal and lathyritic chick embryos bone collagen was synthesized primarily in the periosteum of the femurs, and was organized as radioactive spicules in these bones. Saline extraction of the lathyritic bones removed the radioactive spicules, although they eventually seemed to become non-extractable. Normal bone seemed to be unaffected by saline extraction. Marked variation in the degree of isotope incorporation was seen in collagenous and non-collagenous tissues. All the tissues of any one embryo, however, showed a similar degree of isotope incorporation. Tritiated beta-aminopropionitrile was diffusely distributed throughout bone and was completely removed by saline extraction. This autoradiographic study supports the postulate that a portion of extractable lathyritic collagen is recently synthesized and is organized in fibrous structures in bone.

Aminopropionitrile↗

Height and weight measurements of male Turkish adolescents according to biological maturation.

Eight hundred and seventy-nine Turkish male adolescents aged between 11 and 19 years were investigated with respect to their physical development. Bone ages were considered as well as chronological ages in determining biacromial (BAC), biiliac lengths (BIC) and chest circumference (CC). Different bone and chronological ages were obtained at the same chronological age (CA) and bone age (BA) columns. The importance of bone ages in evaluating an adolescent's physical development was shown to be as important as the chronological ages. In this study, the mean BAC, BIC and CC values between the same CA but different BA groups showed statistically significant differences (P < 0.001). When the measurements of two consecutive age groups who had the same CA and BA and who were found to be statistically significant (P < 0.05) were compared, the maximum increments in BAC and BIC values which were between 13 and 14 years of age (2 and 1.4 cm, respectively) were similar to the maximum increment in height and weight of Turkish male adolescents found between 13 and 14 years of BA. The maximum increment in CC values which were between 14 and 15 years and 15 and 16 years (4.1 cm each) was 1 year after the maximum increment in height and weight for BA of Turkish male adolescents (13-14 years) and was similar to maximum weight increment for CA which was between 15 and 16 years.

Adolescent↗

Some observations on the development of the long bones of ratite birds.

Observations were made on the long bones of 16 young ratite birds (10 rheas, 3 emus and 3 ostriches), from 1-day-old to 12 weeks of age. At hatching all long bones contained large cartilaginous cones which were continuous with the growth plates, and an osseous cortex. At one week of age ossification had commenced on the periphery of these embryonic cones and in some bones the cones had become separated from the growth plates. At 3 weeks of age the embryonic cones of cartilage were still present in the proximal and distal tibio-tarsi and narrow cartilaginous bridges connected the cones to the growth plates. Embryonic cones were not present in other long bones of this 3-week-old rhea nor in the long bones of ratites 6, 8 and 12 weeks of age. Other praecocial birds such as turkey poults and chickens have cones of embryonic cartilage in their long bones at hatching and these persist in the tibio-tarsi till one to 2 weeks of age. The presence of large cones of embryonic cartilage in the tibio-tarsal bones of 3-week-old ratite birds is probably a normal phenomenon. Awareness of this feature is necessary for the correct differential diagnosis of the prevalent musculoskeletal disorders of ratite birds.

Animals↗

TETRACYCLINE: EFFECT ON OSTEOGENESIS IN VITRO.

Tetracycline hydrochloride added to cultures of rudiments of embryonic bone in a concentration of 1 microgram per milliliter prevents mineralization of the bones and is found throughout the calcified zones. The inhibition is reversible; upon transfer of a treated culture to a normal medium, mineralization proceeds normally but maldeveloped bones result.

Animals↗

[In vitro assessment of combining osteogenic cells with macroporous calcium-phosphate ceramics].

PURPOSE OF THE STUDY: Bone grafts or bone substitutes are required to fill bone defects resulting from trauma or surgical resection of tumors. Calcium-phosphate ceramics are synthetic bone substitutes which promote new bone formation by osteoconduction. These ceramics possess osteoconductive properties but have no intrinsic osteoinductive capacity. They are unable to induce new bone formation in extraossesous sites. One solution to develop bone substitutes with osteogenic properties would be to associate biomaterials with osteoprogenitors. MATERIALS AND METHODS: We studied the in vitro osteogenic potential of human bone-marrow cells cultured on macroporous calcium phosphate (CaP) ceramic, examining stromal cell proliferation and differentiation. Osteogenic differentiation was evaluated in terms of alkaline phosphatase activity and immunological characterization of the extracellular fibrillar matrix formed by these cells. The specimens were examined by scanning and transmission electron microscopy. RESULTS: Human bone-marrow cells proliferated on CaP ceramic. The proliferating bone-marrow cells expressed an osteoblastic phenotype as shown by alkaline phosphatase activity and synthesis in ceramic pores of an extracellular matrix composed of fibronectin, osteocalcin and collagen I. In addition, numerous microcrystals of apatite precipitated on the fibrillar matrix, producing a mineralized fibrillar network within the ceramic. CONCLUSION: This study demonstrates that human bone-marrow cells cultured on macroporous CaP ceramic do not lose their osteoblastic phenotype even after 21 days of culture, and that they can induce osteogenesis in a CaP ceramic in vitro. This type of new "hybrid material" appears promising for the future.

Bone Marrow Cells↗

[Application of biochemical markers of bone metabolism in the assessment of secondary osteoporosis in rheumatoid arthritis patients].

Assessment of abnormality of bone mineral metabolism in osteoporosis is made easier by means of newly developed bone metabolic markers. In primary osteoporosis, patients who show high turnover of bone metabolism have high risk of fracture. In RA patients, as bone metabolism is usually high turnover and incidence of insufficiency stress fracture is very frequent, assessment of bone metabolism is more important. Because of poor activity of daily living of RA patients, development of convenient method to collect specimen for examination of bone metabolism and to measure local bone metabolism are important.

English Abstract↗