Influence of decreasing nutrient path length on the development of engineered cartilage

SummaryObjectiveChondrocyte-seeded agarose constructs of 4mm diameter (2.34mm thickness) develop spatially inhomogeneous material properties with stiffer outer edges and a softer central core suggesting nutrient diffusion limitations to the central construct region [Guilak F, Sah RL, Setton LA. Physical regulation of cartilage metabolism. In: Mow VC, Hayes WC, Eds. Basic Orthopaedic Biomechanics, Philadelphia 1997;179–207.]. The effects of reducing construct thickness and creating channels running through the depth of the thick constructs were examined.MethodsIn Study 1, the properties of engineered cartilage of 0.78mm (thin) or 2.34mm (thick) thickness were compared. In Study 2, a single nutrient channel (1mm diameter) was created in the middle of each thick construct. In Study 3, the effects of channels on larger 10mm diameter, thick constructs were examined.ResultsThin constructs developed superior mechanical and biochemical properties than thick constructs. The channeled constructs developed significantly higher mechanical properties vs control channel-free constructs while exhibiting similar glycosaminoglycan (GAG) and collagen content. Collagen staining suggested that channels resulted in a more uniform fibrillar network. Improvements in constructs of 10mm diameter were similarly observed.ConclusionsThis study demonstrated that more homogeneous tissue-engineered cartilage constructs with improved mechanical properties can be achieved by reducing their thickness or incorporating macroscopic nutrient channels. Our data further suggests that these macroscopic channels remain open long enough to promote this enhanced tissue development while exhibiting the potential to refill with cell elaborated matrix with additional culture time. Together with reports that <3mm defects in cartilage heal in vivo and that irregular holes are associated with clinically used osteochondral graft procedures, we anticipate that a strategy of incorporating macroscopic channels may aid the development of clinically relevant engineered cartilage with functional properties

In vitro Antibacterial Activity of Herbal Medicines and Combinations of Herbal Medicines and Antibiotics against Edwardsiella tarda

The antibacterial activity of five medicinal herbs, alone and together with other herbs or one of six antibiotics, against Edwardsiella tarda was determined by World Health Organization-International Collaborative Study (WHO-ICS) agar dilution protocol. Minimal inhibitory concentrations (MIC) of the herbs were significantly lower (≤4 mg/ml) in treatments using the combinations Rhizoma coptidis+Radix scutellariae, Galla chinensis+Radix et Rhizoma rhei, Galla chinensis+Radix scutellariae, and Radix et Rhizoma rhei+Radix scutellariae than in treatments using Rhizoma coptidis, Radix et Rhizoma rhei, or Flos lonicerae (≥32 mg/ml). Almost all the combination treatments were more effective than treatment by a single herb. Combinations containing herbal medicines and regular antibiotics resulted in varying results: antibacterial effects increased with some combinations and decreased with others. Galla chinensis is suitable for use with most antibiotics, while streptomycin sulfate is suitable for use with many herbal medicines

Hirfl-CSR facility status and development

The HIRFL-CSR facility come into operation by the end of 2007. During operation in recent years, CSR supplied beam for experiments at several terminals and inside both CSRm and CSRe rings. The experiments covers high resolution mass measurement, cancer therapy research, neutron wall, atomic physics using electron target and internal gas target, using injection beam mainly from the SFC of cyclotron injector. New methods and further developments are required to improve the performance of CSR system including multi-gradients measurement method for beam spot commissioning and beam transfer, nonlinear effect correction and stabilization of isochronous mode of CSRe. For suppling of heverier ion beam with proper ernergy, the cyclotron complex should be enhanced and new injector is proposed to replace SFC as injector of SSC.(9 refs