Small change, big difference: A promising praziquantel derivative designated P96 with broad-spectrum antischistosomal activity for chemotherapy of schistosomiasis japonica.

BACKGROUND: Praziquantel (PZQ) has been the first line antischistosomal drug for all species of Schistosoma, and the only available drug for schistosomiasis japonica, without any alternative drugs since the 1980s. However, PZQ cannot prevent reinfection, and cannot cure schistosomiasis thoroughly because of its poor activity against juvenile schistosomes. In addition, reliance on a single drug is extremely dangerous, the development and spread of resistance to PZQ is becoming a great concern. Therefore, development of novel drug candidates for treatment and control of schistosomiasis is urgently needed. METHODOLOGYS/PRINCIPAL FINDINGS: One of the PZQ derivative christened P96 with the substitution of cyclohexyl by cyclopentyl was synthesized by School of Pharmaceutical Sciences of Shandong University. We investigated the in vitro and in vivo activities of P96 against different developmental stages of S. japonicum. Parasitological studies and scanning electron microscopy were used to study the primary action characteristics of P96 in vitro. Both mouse and rabbit models were employed to evaluate schistosomicidal efficacy of P96 in vivo. Besides calculation of worm reduction rate and egg reduction rate, quantitative real-time PCR was used to evaluate the in vivo antischistosomal activity of P96 at molecular level. In vitro, after 24h exposure, P96 demonstrated the highest activities against both juvenile and adult worm of S. japonicum in comparison to PZQ. The antischistosomal efficacy was concentration-dependent, with P96 at 50µM demonstrating the most evident schistosomicidal effect. Scanning electron microscopy demonstrated that P96 caused more severe damages to schistosomula and adult worm tegument compared to PZQ. In vivo, our results showed that P96 was effective against S. japonicum at all developmental stages. Notably, its efficacy against young stage worms was significantly improved compared to PZQ. Moreover, P96 retained the high activity comparable to PZQ against the adult worm of S. japonicum. CONCLUSIONS: P96 is a promising drug candidate for chemotherapy of schistosomiasis japonica, which has broad spectrum of action against various developmental stage, potentially addressing the deficiency of PZQ. It might be promoted as a drug candidate for use either alone or in combination with PZQ for the treatment of schistosomiasis.

Rationally designed functionally graded porous Ti6Al4V scaffolds with high strength and toughness built via selective laser melting for load-bearing orthopedic applications.

Functionally graded materials (FGMs) with porosity variation strategy mimicking natural bone are potential high-performance biomaterials for orthopedic implants. The architecture of FGM scaffold is critical to gain the favorable combination of mechanical and biological properties for osseointegration. In this study, four types of FGM scaffolds with different structures were prepared by selective laser melting (SLM) with Ti6Al4V as building material. All the scaffolds were hollow cylinders with different three-dimensional architectures and had gradient porosity resembling the graded-porous structure of human bone. Two unit cells (diamond and honeycomb-like unit cells) were used to construct the cellular structures. Solid support structures were embedded into the cellular structures to improve their mechanical performances. The physical characteristics, mechanical properties, and deformation behaviors of the scaffolds were compared systematically. All the as-built samples with porosities of ~52-67% exhibited a radial decreasing porosity from the inner layer to the outer layer, and their pore sizes ranged from ~420 to ~630 µm. The compression tests showed the Young's moduli of all the as-fabricated samples (~3.79-~10.99 GPa) were similar to that of cortical bone. The FGM structures built by honeycomb-like unit cells with supporting structure in outer layer exhibited highest yield strength, toughness and stable mechanical properties which is more appropriate to build orthopedic scaffolds for load-bearing application.

[Characterization of chromate resistance in genetically engineered Escherichia coli expressing chromate ion transporter ChrA].

OBJECTIVE: To construct a genetically engineered Escherichia coli expressing chromate (Cr) ion transporter ChrA and test its Cr resistance capacity. METHODS: ChrA gene was cloned by PCR from the DNA template of Serratia sp. S2 and linked with the prokaryotic vector pET-28a (+). The recombinant vector was transformed into E.coli BL21 (DE3) cells for expression of ChrA protein. Cr (VI) risistance and Cr (VI) uptake and efflux of the engineered bacteria were tested, and the effects of Cr loading time, oxyanions (ulfate, molybdate, vanadate, tungstate), and respiratory inhibitors (valinomycin, CN-, oligomycin, and NADH) on Cr (VI) efflux were examined to analyze the pathway of Cr (VI) transport by ChrA protein. RESULTS: The engineered E. coil strain was successfully constructed. Experiments using cell suspensions showed a lowered Cr2O72- uptake but an increased efflux capacity of ChrA-engineered bacteria compared with the control strain (P<0.05). The engineered E. coil cells in exponential growth incubated for 30 min in the presence of 50 mg/L Cr2O72- showed a total displacement of Cr (VI) of 20% after resuspension in PBS at 10 min, but chromate efflux decreased subsequently as the incubation time extended. Oxyanions sulfate and molybdate significantly inhibited chromate efflux in the engineered bacteria (P<0.05), whereas tungstate and vanadate did not obviously affect chromate efflux; chromate efflux was significantly inhibited by K+ ionophore valinomycin and CN-, enhanced by NADH (P<0.05), but not affected by oligomycin, suggesting the role of chromate transporter ChrA as a chemiosmotic pump that extrudes chromate using the proton-motive force. CONCLUSION: ChrA can efficiently transport chromate ions from the cytoplasm to enhance chromate resistance of the genetically engineered E. coli.

[Interference of HIF-1alpha by RNA reduces the expression of matrix metalloproteinase-2 in human cervical carcinoma HeLa cells].

BACKGROUND & OBJECTIVE: Hypoxia inducible factor-1 alpha (HIF-1alpha) is a hypoxia-responsive factor, which commonly exists in the tissues of solid tumors. It plays crucial roles in maintaining cell energy metabolism, tumor angiogenesis and metastasis, cell proliferation and apoptosis. This study was to investigate the effect of silencing HIF-1alpha by RNA interference on the expression of matrix metalloproteinase-2 (MMP-2) in human cervical carcinoma HeLa cells, and to further explore the mechanism. METHODS: Fifteen nude mice were divided into three groups randomly, and were inoculated with HeLa cells, pGenesil-1-HeLa cells and HIF-1alpha-HeLa cells, respectively. Expressions of HIF-1alpha, E-cadherin, beta-catenin, MMP-2 in the xenograft tumors of nude mice were detected by immunohistochemistry. pGenesil-1-HeLa or HIF-1alpha-HeLa cells were cultured under a hypoxic(1% O2) or normoxic environment for 48 h, while HeLa cells were cultured under the same condition as control. Expressions of HIF-1alpha, E-cadherin, beta-catenin and MMP-2 were measured by Western blot. RESULTS: In HeLa, pGenesil-1-HeLa and HIF-1alpha-HeLa cell xenograft groups, the positive rates of HIF-1alpha protein were (69.0+/-12.1)%, (62.8+/-12.3)% and (17.4+/-8.8)%, respectively; expressions of E-cadherin were 1.00+/-0.07, 1.00+/-0.10, 3.21+/-0.25; expressions of beta-catenin were 4.21+/-0.92, 4.31+/-0.87, 1.29+/-0.72; and expressions of MMP-2 were 4.84+/-0.67, 4.50+/-0.71 and 1.00+/-0.83. HIF-1alpha and MMP-2 were positively correlated (correlation coefficient=0.521). Expressions of HIF-1alpha, beta-catenin and MMP-2 protein were low and that of E-cadherin protein was high in HIF-1alpha-HeLa cells under hypoxia or normoxia for 48 h; while opposite results were obtained in HeLa and pGenesil-1-HeLa cells. CONCLUSION: Inhibition of HIF-1alpha could effectively down-regulate the expression of MMP-2 in human cervical carcinoma Hela cells.