Bladder regeneration by collagen scaffolds with collagen binding human basic fibroblast growth factor

PURPOSE

Studies show that basic fibroblast growth factor can promote bladder regeneration. However, the lack of targeting delivery approaches limits its clinical application. We investigated a collagen based targeting system for bladder regeneration. A collagen binding domain was added to the native basic fibroblast growth factor N-terminal to allow it to bind to collagen.

MATERIALS AND METHODS

Sprague-Dawley rats underwent partial cystectomy. Collagen scaffolds loaded with collagen binding domain basic fibroblast growth factor, native basic fibroblast growth factor or phosphate buffered saline were grafted to the remaining host bladders, respectively. At days 30 and 90 reconstructed bladders were evaluated by histological analysis and urodynamics.

RESULTS

This targeting basic fibroblast growth factor delivery system induced satisfying bladder histological structures. It promoted more vascularization and smooth muscle cell ingrowth. Urodynamics revealed well accommodated bladder tissue with volume capacity and compliance.

CONCLUSIONS

Results show that the targeting delivery system consisting of collagen binding domain basic fibroblast growth factor and collagen membranes induced better bladder regeneration at the injury site. Thus, this targeting delivery system may be an effective strategy for bladder regeneration with potential clinical applications.

Impact of pulse forming network and injection current parameters on output and energy variations of helical tomotherapy

PURPOSE

In this study, an experiment was devised to establish the dependency of the impact of pulse forming network (PFN) and injection current (IC) parameters on output and energy variations of helical tomotherapy (HT) on the radiation beam output and energy.

METHODS

HT has unique radiation beam characteristics due to the absence of a flattening filter. As with conventional linear accelerators, the machine output and energy should be within a + or - 2% tolerance according to published studies. However, because a dose servo is not utilized in a HT unit, these parameters may drift out of the + or - 2% tolerance due to various reasons such as high machine temperatures. With this in mind, physicists and engineers must adjust certain machine parameters to reset the output and energy to within the tolerance of the commissioned baseline. Two parameters commonly adjusted are: PFN voltage (V(PFN)) and IC voltage (V(IC)).

RESULTS

Results showed that the HT unit possesses different working zones defined by the V(PFN) and V(IC) parameter settings. The working zones were classified into 5 zones: 1) low dose rate zone - radiation dose rate much lower than nominal dose rate and machine cannot run due to low dose rate fault; 2) normal dose rate zone - dose rate is within tolerance of nominal dose rate and machine can run without dose rate fault; 3) dose rate failure during treatment zone - dose rate within the tolerance of the nominal dose rate however machine interrupts during treatment due to dose rate fault; 4) high dose rate zone - dose rate is higher than nominal dose rate and machine cannot run due to high dose rate fault; and 5) inoperable dose rate zone - dose rate is much higher than the nominal dose rate and machine cannot run.

CONCLUSION

The results of this study may provide a quick guide for physicists to adjust their HT unit V(PFN) and V(IC) values in order to reset the radiation beam output and energy back to within the tolerance of the commissioned baseline.

TLRs antiviral effect on hepatitis B virus in HepG2 cells

AIMS

A hepatoma cell line, HepG2, was used as a model system to detect Toll-like receptor (TLR) expression in hepatocytes and examine the antiviral effect on hepatitis B virus (HBV).

METHODS AND RESULTS

Toll-like receptor expression was detected in HepG2 cells by RT-PCR. The TLRs, which were strongly expressed in HepG2 cells, were stimulated with specific ligands. Interferon (IFN) response was evaluated poststimulation with Western blotting for signal transduction and activators of transcription-1. Furthermore, HepG2 cells were transiently transfected with wild-type HBV 1.3-fold over-length plasmid and treated with specific ligands at indicated times. Replication of HBV DNA, transcription of HBV RNA intermediate and expression of HBV antigens were respectively detected by Southern blotting, real time PCR, ELISA and Western blotting. Activation of different TLRs induced antiviral effects on HBV to varying degrees.

CONCLUSIONS

The TLRs, which were strongly expressed in HepG2 cells, could be stimulated with specific ligands. Activation of TLRs induced apparent production of antiviral cytokines such as IFN-alpha/beta and inhibited HBV lifecycle in the hepatocyte cell model.

SIGNIFICANCE AND IMPACT OF THE STUDY

Expression of TLRs in hepatocytes may be related to local immunity of liver and participate in the outcome of viral hepatitis.

Electrodeposition and capacitive behavior of films for electrodes of electrochemical supercapacitors

Polypyrrole films were deposited by anodic electropolymerization on stainless steel substrates from aqueous pyrrole solutions containing sodium salicylate and tiron additives. The deposition yield was studied under galvanostatic conditions. The amount of the deposited material was varied by the variation of deposition time at a constant current density. SEM studies showed the formation of porous films with thicknesses in the range of 0-3 μm. Cyclic voltammetry data for the films tested in 0.5 M Na2SO4 solutions showed capacitive behavior and high specific capacitance (SC) in a voltage window of 0.9 V. The films prepared from pyrrole solutions containing tiron showed better capacitive behavior compared to the films prepared from the solutions containing sodium salicylate. A highest SC of 254 F g-1 was observed for the sample with a specific mass of 89 μg cm-2 at a scan rate of 2 mV s-1. The SC decreased with an increasing film thickness and scan rate. The results indicated that the polypyrrole films deposited on the stainless steel substrates by anodic electropolymerization can be used as electrodes for electrochemical supercapacitors (ES).

Enzymatic properties of the 20S proteasome in wheat endosperm and its biochemical characteristics after seed imbibition

The 20S proteasome from wheat (Triticum aestivum L., Yangmai 158) endosperm was purified to apparent homogeneity by three sequential centrifugations and gradient PAGE (GPAGE). The purified 20S proteasome clearly cleaved peptidyl-arylamide bonds in the model synthetic substrates Z-GGL-AMC and Z-GGR-AMC, which are used to reflect chymotrypsin-like and trypsin-like activity, respectively. For both substrates, the optimum pH was 8.0, but the optimum temperatures for chymotrypsin-like and trypsin-like activity were 55 degrees C and 37 degrees C, respectively. Both enzyme activities were clearly inhibited by MG115 and PMSF. Polyubiquitinated proteins remained constant from 0 to 7 days after seed imbibition, but caseinolytic activity and the amount of the 20S proteasome associated with the aleurone layer decreased from 1 to 2 days after imbibition (DAI), then increased from 2 to 4 DAI, and reached a maximum at 4 DAI that was retained until 7 DAI. An increase was seen in the mRNA level of the beta5 subunit of the 20S proteasome from 2 DAI, and caseinolytic activity and the amount of the 20S proteasome increased from 3 DAI onwards. In addition, the main storage proteins of the wheat endosperm could not be hydrolyzed by the 20S proteasome. The evidence suggests that the main role of the 20S proteasome may not be to degrade massive proteins of the wheat endosperm after seed imbibition.

The osteogenic effect of bone morphogenetic protein-2 on the collagen scaffold conjugated with antibodies

Considerable research has been focused on the exploration of bone morphogenetic protein-2 (BMP(2)) delivery vehicles for achieving prolonged availability and maintaining efficient local concentration at the bone injury sites. In this study, heterobifunctional cross-linkers Sulfo-SMCC and cyclic thioimidate compound Traut's Reagent were used to conjugate monoclonal polyhistidine antibody on collagen scaffold demineralized bone matrix (DBM) to create specific binding between BMP(2) containing six histidines tag (His-BMP(2)) and DBM. According to the optimized cross-linking reagent concentration, more polyhistidine antibodies conjugated on DBM with 5mg/ml Traut's Reagent and 25ug/ml Sulfo-SMCC than physical adsorption. Monoclonal antibodies conjugated DBM (MAbs-DBM) could bind more His-BMP(2) than DBM and achieved controlled release in vitro. The alkaline phophatase (AP) activity of C2C12 cells on MAbs-DBM indicated that His-BMP(2) retained on MAbs-DBM preserved the function to induce osteogenic differentiation. His-BMP(2)/MAbs-DBM induced more ectopic bone formation (AP activity assay and histochemistry stain) than control group after subcutaneous implantation. The results demonstrated that antibody-collagen system could be useful for maintaining higher local therapy concentration of growth factors at the injury sites.