Comparison of Borate Bioactive Glass and Calcium Sulfate as Implants for the Local Delivery of Teicoplanin in the Treatment of Methicillin-Resistant Staphylococcus aureus-Induced Osteomyelitis in a Rabbit Model.

There is growing interest in biomaterials that can cure bone infection and also regenerate bone. In this study, two groups of implants composed of 10% (wt/wt) teicoplanin (TEC)-loaded borate bioactive glass (designated TBG) or calcium sulfate (TCS) were created and evaluated for their ability to release TEC in vitro and to cure methicillin-resistant Staphylococcus aureus (MRSA)-induced osteomyelitis in a rabbit model. When immersed in phosphate-buffered saline (PBS), both groups of implants provided a sustained release of TEC at a therapeutic level for up to 3 to 4 weeks while they were gradually degraded and converted to hydroxyapatite. The TBG implants showed a longer duration of TEC release and better retention of strength as a function of immersion time in PBS. Infected rabbit tibiae were treated by debridement, followed by implantation of TBG or TCS pellets or intravenous injection with TEC, or were left untreated. Evaluation at 6 weeks postimplantation showed that the animals implanted with TBG or TCS pellets had significantly lower radiological and histological scores, lower rates of MRSA-positive cultures, and lower bacterial loads than those preoperatively and those of animals treated intravenously. The level of bone regeneration was also higher in the defects treated with the TBG pellets. The results showed that local TEC delivery was more effective than intravenous administration for the treatment of MRSA-induced osteomyelitis. Borate glass has the advantages of better mechanical strength, more desirable kinetics of release of TEC, and a higher osteogenic capacity and thus could be an effective alternative to calcium sulfate for local delivery of TEC.

The synthesis of anticancer sulfonated indolo[2,1-a]isoquinoline and benzimidazo[2,1-a]isoquinolin-6(5H)-ones derivatives via a free radical cascade pathway.

A facile CuBr2 induced radical relay addition/cyclization of activated alkenes with substituted-thiosulfonates has been achieved, leading to a broad range of sulfonated indolo[2,1-a]isoquinolines and benzimidazo[2,1-a]isoquinolin-6(5H)-ones in moderate to good yields. In particular, some compounds exhibit bioactivity against cancer cell lines. This protocol shows advantages of low-cost, base-free, simple operation, and broad functional group tolerance.

The progress of small-molecules and degraders against BCR-ABL for the treatment of CML.

Chronic myeloid leukemia (CML) is a malignant disease of the hematopoietic system with crucial pathogenic protein named BCR-ABL, which endangers the life of patients severely. As a milestone of targeted drug, Imatinib has achieved great success in the treatment of CML. Nevertheless, inevitable drug resistance of Imatinib has occurred frequently in clinical due to the several mutations in the BCR-ABL kinase. Subsequently, the second-generation of tyrosine kinase inhibitors (TKIs) against BCR-ABL was developed to address the mutants of Imatinib resistance, except T315I. To date, the third-generation of TKIs targeting T315I has been developed for improving the selectivity and safety. Notably, the first allosteric inhibitor has been in market which could overcome the mutations in ATP binding site effectively. Meanwhile, some advanced technology, such as proteolysis-targeting chimeras (PROTAC) based on different E3 ligand, are highly expected to overcome the drug resistance by selectively degrading the targeted proteins. In this review, we summarized the current research progress of inhibitors and degraders targeting BCR-ABL for the treatment of CML.

Progress in the development of nonpeptidomimetic BACE 1 inhibitors for Alzheimer's disease.

It is believed that the production and accumulation of beta-amyloid (Abeta) peptide is a critical step to the pathogenesis of Alzheimer's disease (AD). BACE 1 (beta-site APP-cleaving enzyme 1 or beta-secretase), the key enzyme required for generating Abeta from the beta-amyloid precursor protein (APP), is regarded as an ideal target for AD therapeutic drug design. Due to low oral bioavailability, metabolic instability and poor ability to penetrate the central nervous system (CNS) of the existing peptidomimetic inhibitors, researchers have paid more attention to the development of nonpeptidomimetic inhibitors in recent years. A number of drug screening approaches and technologies have been used to identify novel nonpeptidomimetic BACE 1 inhibitors. This review mainly focuses on the recent developments in structure-based design and synthesis of the nonpeptidomimetic BACE 1 inhibitors.

Stereoselectivity evaluation of chiral chitosan microspheres delivery system containing rac-KET in vitro and in vivo.

The influence of chiral excipient D-chitosan (CS) on the stereoselective release of racemic ketoprofen (rac-KET) microspheres has been investigated in comparison to those microspheres containing individual enantiomers in vitro and in vivo. Stereoselectivity was observed in vitro release test, with R-KET release slightly higher than that of S-KET, especially in 3% rac-KET loading microspheres. Stereoselectivity is dependent on the content of chiral excipient and pH of release medium. A molecular docking study between CS and KET enantiomers further revealed that S-KET has a stronger interaction with CS compared to R-KET. Moreover, the plasma concentration of KET enantiomers in rats shows substantial differences, as the plasma levels of S-KET were higher than those of R-KET. Plasma levels of enantiomers from the R-KET microspheres had similar stereoselectivity as rac-KET microspheres. The S/R ratio of rac-KET microspheres was significantly lower than that of rac-KET suspension (regular-release formulation) (p<.05), and the differences is 3-5 fold. Besides, rates of R-KET converted to S-KET exhibited differences between rac-KET microspheres and suspension. Similar results were also found between R-KET microspheres and suspension. All investigations suggest that the chitosan interacting preferentially with S-KET to R-KET significantly affect the stereoselective pharmacokinetics of rac-KET from chitosan microspheres in rats.

The Role Of Hepatic Stellate Cells In Promoting Liver Metastasis Of Colorectal Carcinoma.

PURPOSE: Colorectal cancer (CRC) is the most common malignancy in the gastrointestinal tract. The liver is the most common location of CRC metastases, which are the main causes of CRC-related death. However, the mechanisms underlying metastasis of CRC to the liver have not been characterized, resulting in therapeutic challenges. METHODS: The effects of hepatic stellate cells (HSCs) on T cells were evaluated using in vitro mixed lymphocyte reactions (MLRs) and cytokine production assays. HSC-induced CT26 cell migration and proliferation were evaluated in vitro and in vivo. RESULTS: HSCs induced T cell hypo-responsiveness, promoted T cell apoptosis, and induced regulatory T cell expansion in vitro. IL-2 and IL-4 were significantly lower in MLRs incubated with HSCs. Supernatants of MLRs with HSCs promoted CT26 cell proliferation and migration. Furthermore, the presence of HSCs increased the number of liver metastases and promoted proliferation of liver metastatic tumor cells in vivo. CONCLUSION: HSCs may contribute to an immunosuppressive liver microenvironment, resulting in a favorable environment for the colonization of CRC cells in the liver. These findings highlight a potential strategy for treatment of CRC liver metastases.

Astragalus polysaccharide induces the apoptosis of human hepatocellular carcinoma cells by decreasing the expression of Notch1.

Hepatocellular carcinoma (HCC) is the third most frequent cause of cancer death worldwide. Astragalus polysaccharide (APS), the primary active component extracted from a traditional Chinese medicinal herb Astragalus membranaceus, has been proved to exert a marked inhibitory effect on a number of types of human solid tumors. In the present study, we aimed to examine the effects of APS on the survival of the HCC cell line H22 and to elucidate the underlying regulatory mechanisms responsible for these effects. Our results revealed that the mRNA and protein expression of Notch1 was significantly upregulated in the HCC tissues compared with that in the normal tissues. APS decreased cell viability and induced the apoptosis of HCC cells in a concentration-dependent manner, which were evaluated using a cell counting kit-8 (CCK-8) assay and flow cytometric analysis, respectively. Furthermore, APS regulated the expression of apoptosis-related genes (Bcl-2 and BAX) and proteases (caspase-3 and -8). Mechanically, Notch1 expression was found to be suppressed in HCC cells, and further analysis indicated that Notch1 knockdown by siRNA significantly reduced cell viability, suppressed the metastatic capacity and enhanced the apoptosis of HCC cells. Taken together, these findings suggest that Notch1 may be a potential therapeutic target for the treatment of HCC.

Stephanthraniline A suppressed CD4(+) T cell-mediated immunological hepatitis through impairing PKCθ function.

Stephanthraniline A (STA), a C21 steroid isolated from Stephanotis mucronata (Blanco) Merr., was previously shown to inhibit T cells activation and proliferation in vitro and in vivo. The purpose of this study was to further evaluate the in vivo immunosuppressive activity of STA and to elucidate its potential mechanisms. The results showed that pretreatment with STA significantly attenuated concanavalin A (Con A)-induced hepatitis and reduced CD4(+) T cells activation and aggregation in hepatic tissue in mice. STA directly suppressed the activation and proliferation of Con A-induced CD4(+) T cells, and inhibited NFAT, NFκB and MAPK signaling cascades in activated CD4(+) T cells in vitro. Moreover, it was proved that STA inhibited T cells activation and proliferation through proximal T cell-receptor (TCR) signaling- and Ca(2+) signaling-independent way. The molecular docking studies predicted that STA could tight bind to PKCθ via five hydrogen. The further findings indicated STA directly inhibited PKCθ kinase activity, and its phosphorylation in activated CD4(+) T cells in vitro. Collectively, the present study indicated that STA could protect against CD4(+) T cell-mediated immunological hepatitis in mice through PKCθ and its downstream NFAT, NFκB and MAPK signaling cascades. These results highlight the potential of STA as an effective leading compound for use in the treatment of CD4(+) T cell-mediated inflammatory and autoimmune diseases.

A novel injectable borate bioactive glass cement as an antibiotic delivery vehicle for treating osteomyelitis.

BACKGROUND: A novel injectable cement composed of chitosan-bonded borate bioactive glass (BG) particles was evaluated as a carrier for local delivery of vancomycin in the treatment of osteomyelitis in a rabbit tibial model. MATERIALS AND METHODS: The setting time, injectability, and compressive strength of the borate BG cement, and the release profile of vancomycin from the cement were measured in vitro. The capacity of the vancomycin-loaded BG cement to eradicate methicillin-resistant Staphylococcus aureus (MRSA)-induced osteomyelitis in rabbit tibiae in vivo was evaluated and compared with that for a vancomycin-loaded calcium sulfate (CS) cement and for intravenous injection of vancomycin. RESULTS: The BG cement had an injectability of >90% during the first 3 minutes after mixing, hardened within 30 minutes and, after hardening, had a compressive strength of 18 ± 2 MPa. Vancomycin was released from the BG cement into phosphate-buffered saline for up to 36 days, and the cumulative amount of vancomycin released was 86% of the amount initially loaded into the cement. In comparison, vancomycin was released from the CS cement for up 28 days and the cumulative amount released was 89%. Two months post-surgery, radiography and microbiological tests showed that the BG and CS cements had a better ability to eradicate osteomyelitis when compared to intravenous injection of vancomycin, but there was no significant difference between the BG and CS cements in eradicating the infection. Histological examination showed that the BG cement was biocompatible and had a good capacity for regenerating bone in the tibial defects. CONCLUSIONS: These results indicate that borate BG cement is a promising material both as an injectable carrier for vancomycin in the eradication of osteomyelitis and as an osteoconductive matrix to regenerate bone after the infection is cured.

Elution characteristics of teicoplanin-loaded biodegradable borate glass/chitosan composite.

Local antibiotic delivery system has an advantage over systemic antibiotic for osteomyelitis treatment due to the delivery of high local antibiotic concentration while avoiding potential systemic toxicity. Composite biomaterials with multifunctional roles, consisting of a controlled antibiotic release, a mechanical (load-bearing) function, and the ability to promote bone regeneration, gradually become the most active area of investigation and development of local antibiotic delivery vehicles. In the present study, a composite of borate glass and chitosan (designated BG/C) was developed as teicoplanin delivery vehicle. The in vitro elution kinetics and antibacterial activity of teicoplanin released from BG/C composite as a function of immersion time were determined. Moreover, the pH changes of eluents and the bioactivity of the composite were characterized using scanning electron microscopy coupled with energy-dispersive spectroscopy and X-ray diffraction analysis.

In vitro evaluation of cytotoxicity of silver-containing borate bioactive glass.

The cytotoxicity of silver-containing borate bioactive glass was evaluated in vitro from the response of osteoblastic and fibroblastic cells in media containing the dissolution products of the glass. Glass frits containing 0-2 weight percent (wt %) Ag were prepared by a conventional melting and quenching process. The amount of Ag dissolved from the glass into a simulated body fluid (SBF), measured using atomic emission spectroscopy, increased rapidly within the first 48 h, but slowed considerably at longer times. Structural and microchemical analysis showed that the formation of a hydroxyapatite-like layer on the glass surface within 14 days of immersion in the SBF. The response of MC3T3-E1 and L929 cells to the dissolution products of the glass was evaluated using SEM observation of cell morphology, and assays of MTT hydrolysis, lactate dehydrogenase release, and alkaline phosphatase activity after incubation for up to 48 h. Cytotoxic effects were found for the borate glass containing 2 wt % Ag, but not for 0.75 and 1 wt % Ag. This borate glass containing up to ∼1 wt % Ag could provide a coating material for bacterial inhibition and enhanced bioactivity of orthopaedic implant materials such as titanium.

Novel borate glass/chitosan composite as a delivery vehicle for teicoplanin in the treatment of chronic osteomyelitis.

Composite materials composed of borate bioactive glass and chitosan (designated BGC) were investigated in vitro and in vivo as a new delivery system for teicoplanin in the treatment of chronic osteomyelitis induced by methicillin-resistant Staphylococcus aureus (MRSA). In vitro, the release of teicoplanin from BGC pellets into phosphate-buffered saline (PBS), as well as its antibacterial activity, were determined. The compressive strength of the pellets was measured after specific immersion times, and the structure of the pellets was characterized using scanning electron microscopy and X-ray diffraction. In vivo, the tibial cavity of New Zealand White rabbits was injected with MRSA strain to induce chronic osteomyelitis, treated by debridement after 4weeks, implanted with teicoplanin-loaded BGC pellets (designated TBGC) or BGC pellets, or injected intravenously with teicoplanin. After 12weeks' implantation, the efficacy of the TBGC pellets for treating osteomyelitis was evaluated using hematological, radiological, microbiological and histological techniques. When immersed in PBS, the TBGC pellets provided a sustained release of teicoplanin, while the surface of the pellets was converted to hydroxyapatite (HA). In vivo, the best therapeutic effect was observed in animals implanted with TBGC pellets, resulting in significantly lower radiological and histological scores, a lower positive rate of MRSA culture, and an excellent bone defect repair, without local or systemic side effects. The results indicate that TBGC pellets are effective in treating chronic osteomyelitis by providing a sustained release of teicoplanin, in addition to participating in bone regeneration.

The preparation and properties of monodisperse core-shell silica magnetic microspheres.

The monodisperse core-shell silica magnetic microspheres (MMS) were synthesized by sol-gel method gelling in the emulsion. Optical microscope (OM), field emission scanning electron microscope (FESEM), nitrogen adsorption and desorption Brunauer Emmett Teller Procedure (BET) isotherms and Barrett-Joyner-Halenda (BJH) pore size distribution measurements, X-ray diffraction (XRD), energy dispersive spectrometer (EDS) and vibrating sample magnetometer (VSM) were used to characterize the appearance, size distribution, phase, specific surface area, chemical composition and magnetic property of silica MMS. The results showed that silica MMS prepared through sol-gel method with acid-alkali two-step catalyze and gelling in emulsion exhibited the superior core-shell structure and size distribution of the microspheres concentrated in about 20 mum. The main phase of microspheres was amorphous silica and spinel ferroferric oxide. Meanwhile, the microspheres remained the superparamagnetic behavior and could be used as biomaterials.

[In vitro drug release behavior of carrier made of porous glass ceramics].

OBJECTIVE: To conduct the in vitro test on drug release of rifampin encapsulated in a carrier made of porous phosphate glass ceramics and to analyze main factors which affect the drug release rate. METHODS: A certain quantitative of rifampin was sealed in a hollow cylindrical capsule which consisted of chopped calcium phosphate crystal fiber obtained from glass crystallization. The rifampin concentration was measured in the simulated physiological solution in which the capsule soaked. RESULTS: Rifampin could be released in a constant rate from the porous glass ceramic carrier in a long time. The release rate was dependent on the size of crystal fiber and the wall thickness of the capsule. CONCLUSION: This kind of calcium phosphate glass ceramics can be a candidate of the carrier materials used as long term drug therapy after osteotomy surgery.