Strontium enhances proliferation and osteogenic behavior of periodontal ligament cells in vitro

Background and Objective Strontium (Sr) enhances osteogenic differentiation of certain multipotent cells. Periodontal ligament cells (PDLCs) are known to be multipotent, and Sr might be useful in periodontal bone tissue engineering. This study investigates the effect of high concentration of Sr on the proliferation and osteogenic behavior of PDLCs in vitro. Material and Methods Primary human PDLCs were cultured in MEM + 10% FBS without (Ctrl) or with Sr in four diverse concentrations: Sr1, 11.3 × 10−3 mg/L, human serum physiological level; Sr2, 13 mg/L, typical human serum level after strontium ranelate treatment; Sr3, 130 mg/L, and Sr4, 360 mg/L. The spreading area (2, 4, 6, 24 hours), proliferation rate (1, 3, 7 days), osteogenic behavior (alkaline phosphatase ‐ ALP activity, 7 and 14 days; expression of osteogenic genes, ALP, Runt‐related transcription factor 2 ‐ RUNX2, osteopontin ‐ OPN, osteocalcin ‐ OCN, and osteoprotegerin ‐OPG, 1, 3, 7, 14, 21 days), and formation of mineralized nodules (14 and 21 days) of the PDLCs were assessed. Data were compared group‐ and period‐wise using ANOVA tests. Results Periodontal ligament cells cultured with Sr4 showed increased spreading area (after 4 hours), proliferation rate (from 3 days), and OCN and OPN (from 7 days) gene expression as compared to Ctrl, Sr1, Sr2, and Sr3. Sr4 also led to lower ALP activity (from 7 days), ALP (from 3 days), and RUNX2 (at 7 and 14 days) gene expression, together with more evident formation of mineralized nodules, compared to Ctrl, Sr1, Sr2, and Sr3. Conclusion Periodontal ligament cells responded to Sr4 with increased cellular proliferation and osteogenic behavior in vitro

Influência da densidade básica da madeira na qualidade da polpa kraft de clones hibrídos de Eucalyptus grandis W. Hill ex Maiden X Eucalyptus urophylla S. T. Blake Effect of wood basic density on kraft pulp quality of hybrid Eucalyptus grandis W. Hill ex Maiden X Eucalyptus urophylla S.T. Blake clones

Foram estudados dois clones de Eucalyptus com densidades básicas de 447 e 552 kg/m&sup3;. O processo kraft foi utilizado para a produção de celulose, tendo sido aplicadas diferentes cargas de álcali para se obterem polpas com número kappa 18 &plusmn; 0,5. As polpas foram branqueadas pela seqüência ODEopDD, a alvuras de 90 &plusmn; 1% ISO, e refinadas, sendo suas propriedades físico-mecânicas e ópticas analisadas. A madeira de baixa densidade mostrou-se mais recomendável para a produção de celulose, por ter apresentado maior rendimento depurado, viscosidade da polpa mais elevada, ter requerido menor carga de álcali no cozimento, ter proporcionado menor teor de sólidos no licor residual e menor consumo de reagentes químicos no branqueamento. As propriedades mecânicas e estruturais das polpas não foram afetadas significativamente pela densidade básica das madeiras.<br>Two hybrid Eucalyptus clones having 447 kg/m&sup3; and 552 kg/m&sup3; basic densities were used for this study. The kraft process was used for pulping the wood chips to kappa number 18&plusmn;0.5 and different alkali charges were applied to reach this delignification target. Pulp was bleached to 90&plusmn;1% ISO using the ODEopDD bleaching sequence. The bleached pulp was refined and its physical-mechanical properties were determined. The lower density wood was recommended for pulp production due to its lower alkali requirement for pulping, higher screened yield, superior pulp viscosity, lower black liquor solids content and lower bleaching chemical requirement. Wood basic density did not affect significantly the mechanical and structural pulp properties