Longitudinal shrinkage in lower legs: "negative growth" in healthy late-adolescent males.

BACKGROUND/AIMS: We examined the final period of tibial growth in late adolescent males. METHODS: Forty-one healthy male subjects, aged 15.7 to 19.8 years participated in a study on lower leg length (LLL) growth, body height and weight increments. All subjects were measured and weighed at weekly intervals over a period of one year. Body height was determined by an anthropometer, body weight by conventional scales, and LLL was measured by a hand-held knemometer. The state of maturity of the proximal tibial epiphyses was determined by magnetic resonance imaging (MRI). Skeletal maturity was independently assessed by two radiologists. The growth plates were categorized as being open (category I), centrally but not completely fused (category II), or completely fused (category III). RESULTS: Our findings demonstrate that in these adolescents, final tibial growth is characterized by longitudinal shrinkage. As shown in the MRI, when the proximal tibial growth plates have fused (i.e., at an age when lower leg growth is commonly believed to have completed), the lower leg of healthy adolescent males begins to shrink with a negative growth rate of -2.4 (SD 2.1) mm/year. CONCLUSION: Apart from sporadic observations in anorectic girls, longitudinal shrinkage in LLL has not been previously documented. We assume that the final period of growth includes small reductions in bone length, possibly due to stabilization and rearrangements in the formerly growing cartilaginous tissues.

[Degradation of biomolecules in bones: effects of the biological forensics as an example of the stability of isotope ratios in collagen]. / Degradation von Biomolekülen in Knochen: Auswirkung auf die biologische Spurenkunde am Beispiel stabiler Isotopenverhältnisse im Kollagen.

Modern bone samples were experimentally degraded by incubation into water at increased temperature and examined in terms of their collagen content, the stable C and N isotopic ratios, and the molar C/N ratio. The same analyses were carried out with archaeological human bone of varying age (300 up to 8000 years). The experimentally degraded samples exhibited changes of the collagen's integrity, which influence the stable isotope ratios. In the case of the archaeological material, a correlation between stable delta13C- and delta15N-values and collagen content could be demonstrated. The molar C:N ratio was no suitable criterion for the assessment of the state of preservation of extractable collagen.

[Degradation of biomolecules: a comparative study of diagenesis of DNA and proteins in human bone tissue]. / Degradation von Biomolekülen: Eine vergleichende Studie zur Diagenese von DNA und Proteinen in humanem Knochengewebe.

Diagenesis of macromolecules is a not yet fully understood process that can be important for anthropological and forensic research. Trying to elucidate the diagenesis of DNA and proteins we investigated the process of fragmentation of DNA and razemisation of aspartic acid in human bone material. We created an in vitro-model of accelerated aging by incubating bone samples in hot water. A comparison of diagenesis of molecules in those artificially aged samples with altogether 30 historical bones from different regions and of different ages was carried out. The in vitro-model showed the expected positive correlation between the increase of razemisation of aspartic acid and DNA fragmentation, while there was a much lesser correlation when investigating historical bones. The in vitro-model showed the expected correlation between the increase of razemisation of aspartic acid and DNA fragmentation and to a much lesser extent in historical bones. This study shows that diagenesis is probably influenced by additional forces affecting different macromolecules in different ways.