Synthesis and secretion of glycosaminoglycans and proteins in human normal and otosclerotic bone cells.

Some biosynthetic activities of normal and otosclerotic temporal bone cultures have been studied. Bone cells were cultured for 24 hrs. in medium containing 3H-glucosamine, 35SO4 or 3H-proline. Labelled glycosaminoglycans (GAG) and proteins were precipitated from cells and media. In otosclerotic bone cells there was an evident reduction in the synthesis and secretion of radiolabelled macromolecules. The inhibitory effect was always greater in the extracellular than in the intracellular compartment. Some glycosidases were also studied. Otosclerosis decreased the activity of all enzymes examined, indicating that the lower GAG synthesis and secretion in otosclerotic bone cells were not due to an increased degradation.     

Growth forms of annual vascular plants in central Europe

The investigation of the vegetative characters of annual species from central Europe showed a hitherto not regarded large spectrum of 20 growth forms within this plant group. These growth forms can be identified by means of a dichotomous key. This is also a new method to present growth form systems. Although several surveys about growth forms have been carried out, the proposed systems are either incomplete or not consequent in the use of their classifying criteria. Moreover, annual species have never been investigated systematically according to their growth forms. Important characters which were used to characterize growth forms are the occurrence of a rosette, the presence or absence of supporting tissue which causes aerostability or aerolability, succulence, growth direction (plagiotropous, orthotropous) and metamorphoses (for scrambling). According to the mode of surviving the resting period, annuals can be grouped into therophytes, hydrophytes, and hemicryptophytes. Whereas therophytic and hydrophytic annuals perennate the winter exclusively as generative diaspores (seeds, spores), hemicryptophytic species survive as seedlings or young plants.     

Mechanical response of periodontal ligament: Effects of specimen geometry, preconditioning cycles and time lapse

This study was conducted as part of research line addressing the mechanical response of periodontal ligament (PDL) to tensile–compressive sinusoidal loading. The aim of the present project was to determine the effect of three potential sources of variability: (1) specimen geometry, (2) tissue preconditioning and (3) tissue structural degradation over time. For the three conditions, selected mechanical parameters were evaluated and compared.(1) Standard flat specimens (obtained by sequentially slicing portions of bone, PDL and dentin using a precision band saw) and new cylindrical specimens (extracted with a diamond-coated trephine drill) were obtained from bovine mandibular first molars and subjected to a sinusoidal load profile. (2) Specimens were loaded with up to 2000 cycles. (3) Specimens were immersed in saline and tested after 0, 30 and 60 min.From the data generated, the following was concluded: (1) specimen geometry and preparation technique do not influence the mechanical response of the PDL; (2) the mechanical response stabilizes after approximately 1000 cycles; and (3) no major structural degradation occurs when PDL is immersed in saline for a time lapse up to 60 min.     

Concanavalin A affects glycosaminoglycans cellular and extracellular accumulation in cultured embryonic fibroblasts

Incorporation of 3H glucosamine and 35SO4 into glycosaminoglycans and proteoglycans produced and secreted by 7, 11 and 14 day chick embryo fibroblasts in vitro after concanavalin A treatment has been determined. Lectin differently affects 3H and 35SO4 incorporation. It enhances 3H labelled GAG accumulation in both cellular and extracellular compartments. Total incorporation of 35SO4 remains unchanged whereas the intracellular one is stimulated and the extracellular is reduced. All the effects are more relevant in the early stages of development. HA and PG cellular and extracellular accumulation seems to be independently regulated.