In vitro activity of isoimperatorin, alone and in combination, against Mycobacterium tuberculosis

Previous studies have shown that isoimperatorin (IO), a furanocoumarin isolated from several medicinal plants, has antimycobacterial activity against Mycobacterium tuberculosis strain H37Rv (ATCC 27294). This study demonstrated that IO has antimycobacterial activity against 2 drug-sensitive and 6 drug-resistant isolates, with minimum inhibitory concentrations (MICs) of 50-100 μg ml(-1) and 100-200 μg ml(-1), respectively. IO exhibited synergistic antimycobacterial effects with rifampin (RMP), isoniazid (INH) and ethambutol (EMB) against 6 drug-resistant strains, with fractional inhibitory concentration index (FICI) values of 0·133-0·472, 0·123-0·475 and 0·124-0·25, respectively. The IO/RMP, IO/INH and IO/EMB combination treatments had synergistic effects or no interaction in the 2 drug-sensitive strains and the standard strain ATCC 27294. The synergism of combined drugs against drug-resistant strains was better than drug-sensitive strains. No antagonism was observed in with the aforementioned combinations against all strains tested. IO exhibited relatively low cytotoxicity to Vero cells. Our results indicate that IO may serve as promising a template for future antimycobacterial drug development.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first report on the in vitro synergistic antimycobacterial effects of isoimperatorin (IO) in combination with three first-line drugs: rifampin (RMP), isoniazid (INH) and ethambutol (EMB). The results indicated that the antimycobacterial activity of IO was modest; however, IO was a useful and effective agent against Myco. tuberculosis when it was combined with first-line antimycobacterial drugs and is worthy of further development as a lead compound for the development of novel antimycobacterial therapeutic agents.

Absence of static loop-current magnetism at the apical oxygen site in HgBa2CuO4+δ from NMR

The simple structure of HgBa(2)CuO(4+δ) (Hg1201) is ideal among cuprates for study of the pseudogap phase as a broken symmetry state. We have performed (17)O nuclear magnetic resonance on an underdoped Hg1201 crystal with a transition temperature of 74 K to look for circulating loop currents proposed theoretically and inferred from neutron scattering. The narrow spectra preclude static local fields in the pseudogap phase at the apical site, suggesting that the moments observed with neutrons are fluctuating. The nuclear magnetic resonance frequency shifts are consistent with a dipolar field from the Cu(2+) site.

Long-term self-renewal of human pluripotent stem cells on peptide-decorated poly(OEGMA-co-HEMA) brushes under fully defined conditions

Realization of the full potential of human induced pluripotent stem cells (hiPSC) in clinical applications requires the development of well-defined culture conditions for their long-term growth and directed differentiation. This paper describes a novel fully defined synthetic peptide-decorated substrate that supports self-renewal of hiPSC in commercially available xeno-free, chemically defined medium. The Au surface was deposited by a poly(OEGMA-co-HEMA) film, using the surface-initiated polymerization method (SIP) with the further step of carboxylation. The hiPSC generated from umbilical cord mesenchymal cells were successfully cultured for 10 passages on the peptide-tethered poly(OEGMA-co-HEMA) brushes for the first time. Cells maintained their characteristic morphology, proliferation and expressed high levels of markers of pluripotency, similar to the cells cultured on Matrigel™. Moreover, the cell adhesion could be tuned by the pattern and peptide concentration on the substrate. This well-defined, xeno-free and safe substrate, which supports long-term proliferation and self-renewal of hiPSC, will not only help to accelerate the translational perspectives of hiPSC, but also provide a platform to elucidate the underlying molecular mechanisms that regulate stem cell proliferation and differentiation via SIP technology.

Doping-dependent photon scattering resonance in the model high-temperature superconductor HgBa2CuO4+δ revealed by Raman scattering and optical ellipsometry

We study the model high-temperature superconductor HgBa(2)CuO(4+δ) with electronic Raman scattering and optical ellipsometry over a wide doping range. The dependence of the resonant Raman cross section on the incident photon energy changes drastically as a function of doping, in a manner that corresponds to a rearrangement of the interband optical transitions seen with ellipsometry. This doping-dependent Raman resonance allows us to reconcile the apparent discrepancy between Raman and x-ray detection of magnetic fluctuations in superconducting cuprates. Intriguingly, the strongest variation occurs across the doping level where the antinodal superconducting gap appears to reach its maximum.

An artificial model for studying fluid dynamics in the obstructed and stented ureter

Fluid dynamics in the obstructed and stented ureter represents a non-trivial subject of investigation since, after stent placement, the urine can flow either through the stent lumen or in the extra-luminal space located between the stent wall and the ureteric inner wall. Fluid dynamic investigations can help understanding the phenomena behind stent failure (e.g. stent occlusions due to bacterial colonization and encrustations), which may cause kidney damage due to the associated high pressures generated in the renal pelvis. In this work a microfluidic-based transparent device (ureter model, UM) has been developed to simulate the fluid dynamic environment in a stented ureter. UM geometry has been designed from measurements on pig ureters. Pressure in the renal pelvis compartment has been measured against three variables: fluid viscosity (μ), volumetric flow rate (Q) and level of obstruction (OB%). The measurements allowed a quantification of the critical combination of μ, Q and OB% values which may lead to critical pressure levels in the kidney. Moreover, an example showing the possibility of applying particle image velocimetry (PIV) technology to the developed microfluidic device is provided.

The isolation and characterization of a telomerase immortalized goat trophoblast cell line

Trophoblast cells play vital roles in the processes of embryonic implantation and placentation. Many toxicological compounds can induce the malfunction of trophoblast cells, resulting in implantation failure or early embryonic loss. The finite lifespan of primary trophoblast cells limits investigation of the long-term effects of some toxicological compounds on trophoblast cells in vitro. In this study, primary goat trophoblast cells were purified by density gradient centrifugation and specific immuno-affinity purification. Then, the purified cells were immortalized through transfection of a plasmid containing the human telomerase reverse transcriptase (hTERT) gene. hTERT-transfected goat trophoblast cells (hTERT-GTCs) could steadily express hTERT gene and exhibit higher telomerase activity, and persistently proliferate without any signs of senescence up to 50 passages. The immortalized goat trophoblast cells still possessed the basic and key properties of normal primary goat trophoblast cells to express the specific intracellular marker cytokeratin 7 (CK-7) and secrete chorionic gonadotrophin β-subunit (CG-β) and placental lactogen (PL). Further studies showed that the immortalized goat trophoblast cells expressed vimentin and non-classical MHC class I antigen and exhibited invasive phenotype, suggesting that the immortalized goat trophoblasts resembled human extravillous trophoblasts. In addition, this cell line did not show neoplastic transformation either in vivo or in vitro. We concluded the immortalized goat trophoblast cells by hTERT transfection retained the basic and key characteristics of primary trophoblast cells and may provide a useful model to study the effects of some toxicological compounds on trophoblast cells.

Optimal conditions for "heat-conduct effect" in liver tissue during radiofrequency ablation

AIM

This study was conducted to optimize the "heat-conduct effect" to increase the efficacy of radiofrequency ablation (RFA) in the treatment of liver tumors.

METHODS

To simulate the "heat-conduct effect" caused by RFA, isolated pig livers were heated by an inserted metal tube through which water with different incoming temperatures was passed. The tissue temperature was measured within 5- and 10-mm radiuses. Further, changes in color and morphology of the tissue were recorded.

RESULTS

Using an incoming temperature of 70 °C, the effective ablation radius of 5 mm was achieved within 10 min. To expand the effective radius to 10 mm, the tube temperature needed to be maintained at above 80 °C for 40 min; alternatively, the tube temperature above 90 °C and heating time of 25 min were also sufficient.

CONCLUSION

To achieve the complete ablation in isolated liver within the 10 mm radius by "heat-conduct effect", the temperature of the heating center should be maintained above 80 - 90 °C with the exposure time of 25-40 min.