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Advanced studies of single stranded endogenous ~22 nt microRNAs (miRNAs) have demonstrated their diverse biological functions including control of cell differentiation, cell cycle and pathological conditions. Recent studies suggest the potential application of miRNAs in stem cell engineering. miRNAs play a vital role as post-transcriptional regulators of gene expression which controls osteoblasts-mediated bone formation and osteoclasts related bone remodeling. Transcriptional and post-transcriptional mechanisms regulate the differentiation of osteoblasts and osteogenesis. The differentiation of osteoblasts is a key step in the development of skeletal muscles and it is involved in triggering the signaling pathways. Signaling pathways like TGF, BMP and Wnt are regulated by miRNAs which in turn, are shown to be associated with bone dynamics and bone disorders. This recap highlights the role of miRNAs in osteoblasts differentiation and emphasizes their potential therapeutic role in metabolic bone disorders.

Heat shock protein 65 (HSP65) is one of the most important protective immunogens against the tuberculosis infection. The signal sequence of antigen 85B and the whole HSP65 DNA sequence of humanMycobacterium tuberculosis (M. tuberculosis)were amplified from BCG genome and plasmid pCMV-MTHSP65 respectively by polymerase chain reactions (PCR). These two sequences were cloned into the plasmid pBCG-2100 under the control of the promoter of heat shock protein 70 (HSP70) from humanM. tuberculosis, yielding the prokaryotic shuttle expression plasmid pBCG-SP HSP65. Results of restriction endonuclease analysis. PCR detection and DNA sequencing analysis showed that the two cloned DNA sequences were consistent with those previously reported, and the direction of their inserting into the recombinant was correct and the reading frame had been maintained. The recombinants were electroporated into BCG to construct the recombinant BCG vaccine and induced by heating. The induced expression detected by SDS-PAGE showed that the content of 65 kD protein expressed in recombinant BCG was 35.69% in total bacterial protein and 74.09% in the cell lysate supernatants, suggesting that the recombinant HSP65 gene could express in BCG with high efficiency and the expressed proteins were mainly soluble. Western-blot showed that the secretive recombinant proteins could specifically combine with antibody againstM. tuberculosisHSP65, indicating that the recombinant proteins possess the biological activity of HSP65.

We present a simple analytical method to study birefringence and polarization mode dispersion (PMD) of graded-core stress-applied polarization-maintaining fibers. It is based on the equivalent step-index-fiber method. It is shown that the agreement between present results and the results obtained using the finite-element method is very good. Polarization characteristics of stress-applied polarization-maintaining fibers having a dip in the refractive index at the center of the core are also investigated.

To construct a recombinant plasmid Pet23a-M, the gene encoding severe acute respiratory syndrome (SARS) coronavirus membrane protein was amplified by RT-PCR and cloned into the expression plasmid Pet23a. Results of restriction endonuclease analysis, PCR detection and DNA sequencing analysis revealed that the cloned DNA sequence was the same as that reported. The recombinants were transformed intoEscherichia coli(E. Coli) BL21 (DE3) and induced by Isopropyl-β-D-thiogalactopyranoside (IPTG). The expression of 27 kD (1 kD=0.992 1 ku) protein was detected by SDS-PAGE and pured by metal chelated chromatography. Results of Western-blot showed that this expressed protein could react with antibodies in sera of SARS patients during convalescence. This provided the basis for the further study on SARS virus vaccine and diagnostic agents.

Remarkably simple, analytical expressions are presented for the calculation of the birefringence in stress-applied polarisation-maintaining optical fibres. The method is based on the vector analysis of propagation constants in dielectric waveguides with perturbed refractive-index profile. It is shown that present results agree well with the results obtained using the finite-element method.

A graded-core single-polarisation fibre is proposed, and the dispersion equation for its modes is obtained. Very simple asymptotic formulas are derived giving the cutoff frequency as a function of K which determines the depth of the depressions of the cladding when K is small. By incorporating stress anisotropy, it is found that the absolute single-polarisation frequency bandwidth can be increased in the graded-core, stress-applied polarisation-maintaining fibres compared with the conventional step-index profile. The relative frequency bandwidth is approximately the same for the graded-core or step-index profiles.