Supraorganized collagen enhances Schwann cell reactivity and organization in vitro

We investigated the reactivity and expression of basal lamina collagen by Schwann cells (SCs) cultivated on a supraorganized bovine-derived collagen substrate. SC cultures were obtained from sciatic nerves of neonatal Sprague-Dawley rats and seeded on 24-well culture plates containing collagen substrate. The homogeneity of the cultures was evaluated with an SC marker antibody (anti-S-100). After 1 week, the cultures were fixed and processed for immunocytochemistry by using antibodies against type IV collagen, S-100 and p75NTR (pan neurotrophin receptor) and for scanning electron microscopy (SEM). Positive labeling with antibodies to the cited molecules was observed, indicating that the collagen substrate stimulates SC alignment and adhesion (collagen IV labeling - organized collagen substrate: 706.33 ± 370.86, non-organized collagen substrate: 744.00 ± 262.09; S-100 labeling - organized collagen: 3809.00 ± 120.28, non-organized collagen: 3026.00 ± 144.63, P < 0.05) and reactivity (p75NTR labeling - organized collagen: 2156.33 ± 561.78, non-organized collagen: 1424.00 ± 405.90, P < 0.05; means ± standard error of the mean in absorbance units). Cell alignment and adhesion to the substrate were confirmed by SEM analysis. The present results indicate that the collagen substrate with an aligned suprastructure, as seen by polarized light microscopy, provides an adequate scaffold for SCs, which in turn may increase the efficiency of the nerve regenerative process after in vivo repair.

Type collagen synthesis by rats fed beans (phaseolus vulgaris, L.) as the protein source

Type collagen synthesis was studied in 12 female Wistar rats weighing 60 ñ 5 g at the beginning of the experiment. the animals were fasted for 24 h and then injected ip with 10 uCi unifromity labeled [14C]-glycine. Two hours later, groups of 4 animals each were fed balanced diets (10.7 ñ 0.4% protein) containing raw beans (Phaseolus vulgaris, L.) as the protein source, ad libitum. The animals were killed after 4 days and collagen was extracted from the tail and calcaneal tendons. Food intake and weight gain of rats fed raw beans (22 g, 0 g) were considerably less than rats fed cooked beans (38 g, 9 g) and casein (44 g, 22 g). Collagen was quantitated on the basis of hydroxyproli9ne and corresponded to 1, 0.2% rat body weight with specific radioactivity of 1.2, 1.6 and 4.2 uCl/g, for the rats fed raw beans, cooked beans and casein, respectively. The results indicate that rats fed either bean protein synthesized less collagen than those fed casein (P<0.05). Although the food intake and extractable collagen of rats fed cooked beans were similar to those of casein-fed rats, weight gain and collagen specific radioactivity were less

Ossificacao endocondral e ectopica: aspectos estruturais e ordem molecular. / Endochondral and ectopic ossification. Structural aspects and molecular order

A ossificacao engloba uma serie de fenomenos complexos que exigem, do ponto de vista cientifico, uma teoria basica para sua abordagem sistematica, de tal sorte a propiciar um progresso constante no seu conhecimento e simultanea reformulacao de hipoteses e conceitos. Assim, e proposto que a matriz organica do osso seja estruturada por um edificio macromolecular altamente ordenado, hierarquizado, como consequencia de uma interacao preferencial entre radicais determinados de seus biopolimeros, sem o que nao sera possivel morfogenese, crescimento e mineralizacao.Neste trabalho procurou-se mostrar que na matriz extracelular durante a ossificacao endocondral, no periosteo e na ossificacao ectopica induzida, ha um modelo de ordem molecular que antecede mesmo a mineralizacao. Alguns aspectos da ossificacao estao analisados por metodos radioautograficos, citoquimicos, ultra-estruturais opticos (anisotropias opticas) e por microscopia eletronica