Assessment of inhalation exposure to microplastic particles when disposable masks are repeatedly used

Wearing masks to prevent infectious diseases, especially during the COVID-19 pandemic, is common. However, concerns arise about inhalation exposure to microplastics (MPs) when disposable masks are improperly reused. In this study, we assessed whether disposable masks release inhalable MPs when reused in simulated wearing conditions. All experiments were conducted using a controlled test chamber setup with a constant inspiratory flow. Commercially available medical masks with a three-layer material, composition comprising polypropylene (PP in the outer and middle layers) and polyethylene (PE in the inner layer), were used as the test material. Brand-new masks with and without hand rubbing, as well as reused medical masks, were tested. Physical properties (number, size, and shape) and chemical composition (polymers) were identified using various analytical techniques such as fluorescence staining, fluorescence microscopy, and micro-Fourier Transform Infrared Spectroscopy (μFTIR). Scanning Electron Microscopy (SEM) was used to scrutinize the surface structure of reused masks across different layers, elucidating the mechanism behind the MP generation. The findings revealed that brand-new masks subjected to hand rubbing exhibited a higher cumulative count of MPs, averaging approximately 1.5 times more than those without hand rubbing. Fragments remained the predominant shape across all selected size classes among the released MPs from reused masks, primarily through a physical abrasion mechanism, accounting for >90 % of the total MPs. The numbers of PE particles were higher than PP particles, indicating that the inner layer of the mask contributed more inhalable MPs than the middle and outer layers combined. The released MPs from reused masks reached their peak after 8 h of wearing. This implies that regularly replacing masks serves as a preventive measure and mitigates associated health risks of inhalation exposure to MPs.

3D-Cultured Adipose-Derived Stem Cell Spheres Using Calcium-Alginate Scaffolds for Osteoarthritis Treatment in a Mono-Iodoacetate-Induced Rat Model

Osteoarthritis (OA) is a degenerative disease that causes pain, cartilage deformation, and joint inflammation. Mesenchymal stem cells (MSCs) are potential therapeutic agents for OA treatment. However, the 2D culture of MSCs could potentially affect their characteristics and functionality. In this study, calcium-alginate (Ca-Ag) scaffolds were prepared for human adipose-derived stem cell (hADSC) proliferation with a homemade functionally closed process bioreactor system; the feasibility of cultured hADSC spheres in heterologous stem cell therapy for OA treatment was then evaluated. hADSC spheres were collected from Ca-Ag scaffolds by removing calcium ions via ethylenediaminetetraacetic acid (EDTA) chelation. In this study, 2D-cultured individual hADSCs or hADSC spheres were evaluated for treatment efficacy in a monosodium iodoacetate (MIA)-induced OA rat model. The results of gait analysis and histological sectioning showed that hADSC spheres were more effective at relieving arthritis degeneration. The results of serological and blood element analyses of hADSC-treated rats indicated that the hADSC spheres were a safe treatment in vivo. This study demonstrates that hADSC spheres are a promising treatment for OA and can be applied to other stem cell therapies or regenerative medical treatments.

An MRI-Guided Ring High-Intensity Focused Ultrasound System for Noninvasive Breast Ablation

High-intensity focused ultrasound (HIFU) has been used for noninvasive treatment of breast tumors, but the present magnetic resonance imaging (MRI)-guided HIFU (MRI-HIFU) systems encounter skin burn. In this study, a novel MRI-HIFU breast ablation system was developed to improve the above problem. The system consisted of the ring HIFU phased-array transducer, a commercial power amplifier, the mechanical positioner, and the graphical user interface control software. MRI thermometry was also established to monitor the temperature in the HIFU-treated tissue. Ablation of pork and the in vivo rabbit leg were carried out to validate the developed system. Results of fat-surrounding pork ablation showed that the ring HIFU system reached a safe margin of 3 mm without fat burn. Moreover, precision of the positioner moving the HIFU focal zone was within 6% error under MRI circumstances. The representative MRI temperature images show that the peak temperatures among the five ablations ranged between 66 °C and 91 °C, and their thermal doses were over 10000. The system could also ablate the biceps femoris of a rabbit without skin burn to form a lesion of 2.5 mm beneath the skin. With the HIFU dose of 315 W/10 s, the MRI temperature map revealed that the maximum temperature and the thermal dose were 60 °C and 3380, respectively. The MRI-guided ring HIFU system can ablate the target tissue near subcutaneous fat without fat burn. The system prototype is a promising tool for clinical implementation.

A study of Drynaria fortunei in modulation of BMP–2 signalling by bone tissue engineering

Background/aim

Drynaria fortunei (Gusuibu; GSB) is a popular traditional Chinese medicine used for bone repair. An increasing number of studies have reported that GSB induces osteogenic differentiation in bone marrow mesenchymal stem cells (BMSCs). These results provide insight into the application of GSB for bone tissue engineering techniques used to repair large bone defects. However, few studies have described the molecular mechanisms of GSB.

Materials and methods

In the present study, the effects of GSB and naringin, a marker compound, on the binding of BMP-2 to BMPR and BMP-2-derived signal transduction were investigated using surface plasmon resonance (SPR) and coculturing with BMPR-expressed cell line, C₂C₁₂, respectively. Furthermore, naringin was also used to prepare naringin contained scaffolds for bone tissue engineering. The physical and chemical properties of these scaffolds were analysed using scanning electron microscopy (SEM) and highperformance liquid chromatography (HPLC). These scaffolds were cocultured with rabbit BMSCs in vitro and implanted into rabbit calvarial defects for bone repair assessment.

Results

The results showed that GSB and naringin affect the binding of BMP and BMPR in SPR experiments. GSB is a subtle BMP modulator that simultaneously inhibits the binding of BMP-2 to BMPR-1A and enhances its binding to BMPR-1B. In contrast, naringin inhibited BMP-2 binding to BMPR-1A. In vitro studies involving the phosphorylation of signals downstream of BMPR and Smad showed that GSB and naringin affected stem cell differentiation by inhibiting BMPR-1A signalling. When using GSB for bone tissue engineering, naringin exhibited a higher capacity for slow and gradual release from the scaffold, which promotes bone formation via osteoinduction. Moreover, control and naringin scaffolds were implanted into rabbit calvarial defects for 4 weeks, and naringin enhanced bone regeneration in vivo significantly.

Conclusion

GSB and its marker compound (naringin) could inhibit the binding of BMP-2 and BMPR-1A to control cell differentiation by blocked BMPR-1A signalling and enhanced BMPR-1B signalling. GSB and naringin could be good natural BMP regulators for bone tissue engineering.

The preparation of oxidized methylcellulose crosslinked by adipic acid dihydrazide loaded with vitamin C for traumatic brain injury

Oxi-MC-ADH-VC can open up a new avenue for clinical TBI treatment and rehabilitation.

Development of an MRI-Compatible High-Intensity Focused Ultrasound Phased Array Transducer Dedicated for Breast Tumor Treatment

High-intensity focused ultrasound (HIFU) under magnetic resonance imaging (MRI) guidance can achieve a noninvasive and precise ablation of the solid tumor. In the study, an MRI-compatible 1-MHz 16-channel ring-shaped transducer was developed to minimize the burn risk of breast skin and perform volumetric ablation for short treatment time. The measured electroacoustic conversion efficiency of the transducer was 50.90% ± 5. The transducer could produce a point and a quasi-hollow-cylinder lesion in a thermal-sensitive phantom or an ex vivo pork by tuning the phase of each element. It may achieve volumetric ablation of 1.5 cm³ when the point lesion is located inside the hollow lesion. Ex vivo ablation experiments showed that the transducer could cause a coagulative necrosis in the pork from the surrounded subcutaneous fat by 5 mm without fat damage. The temperature and region of the pork ablation were quantified by MRI technique. There was no MRI interference from HIFU and vice versa while both systems operated concurrently.

Cardiac fibrosis in mouse expressing DsRed tetramers involves chronic autophagy and proteasome degradation insufficiency

Proteinopathy in the heart which often manifests excessive misfolded/aggregated proteins in cardiac myocytes can result in severe fibrosis and heart failure. Here we developed a mouse model, which transgenically express tetrameric DsRed, a red fluorescent protein (RFP), in an attempt to mimic the pathological mechanisms ofcardiac fibrosis. Whilst DsRed is expressed and forms aggregation in most mouse organs, certain pathological defects are specifically recapitulated in cardiac muscle cells including mitochondria damages, aggresome-like residual bodies, excessive ubiquitinated proteins, and the induction of autophagy. The proteinopathy and cellular injuries caused by DsRed aggregates may be due to impaired or overburdened ubiquitin-proteasome system and autophagy-lysosome systems. We further identified that DsRed can be ubiquitinated and associated with MuRF1, a muscle-specific E3 ligase. Concomitantly, an activation of NF-κB signaling and a strong TIMP1 induction were noted, suggesting that RFP-induced fibrosis was augmented by a skewed balance between TIMP1 and MMPs. Taken together, our study highlights the molecular consequences of uncontrolled protein aggregation leading to congestive heart failure, and provides novel insights into fibrosis formation that can be exploited for improved therapy.

A Coaxial Dual-element Focused Ultrasound Probe for Guidance of Epidural Catheterization: An Experimental Study

Ultrasound guidance for epidural block has improved clinical blind-trial problems but the design of present ultrasonic probes poses operating difficulty of ultrasound-guided catheterization, increasing the failure rate. The purpose of this study was to develop a novel ultrasonic probe to avoid needle contact with vertebral bone during epidural catheterization. The probe has a central circular passage for needle insertion. Two focused annular transducers are deployed around the passage for on-axis guidance. A 17-gauge insulated Tuohy needle containing the self-developed fiber-optic-modified stylet was inserted into the back of the anesthetized pig, in the lumbar region under the guidance of our ultrasonic probe. The inner transducer of the probe detected the shallow echo signals of the peak-peak amplitude of 2.8 V over L3 at the depth of 2.4 cm, and the amplitude was decreased to 0.8 V directly over the L3 to L4 interspace. The outer transducer could detect the echoes from the deeper bone at the depth of 4.5 cm, which did not appear for the inner transducer. The operator tilted the probe slightly in left-right and cranial-caudal directions until the echoes at the depth of 4.5 cm disappeared, and the epidural needle was inserted through the central passage of the probe. The needle was advanced and stopped when the epidural space was identified by optical technique. The needle passed without bone contact. Designs of the hollow probe for needle pass and dual transducers with different focal lengths for detection of shallow and deep vertebrae may benefit operation, bone/nonbone identification, and cost.

Mechanism of protein phosphatase-2Aregulating phosphorylation of amyloid precursor proteosome and Aβ generation

OBJECTIVE

To discuss whether PP-2A influences the phosphorylation level at APP threonine 668 locus thus regulating Aβ secretion.

METHOD

In the experiment, 24 hours after N2a cells of stably transfected human APP (N2a/APP) were treated with okadaic acid (OA) or DES (C6-ceramide) (N2a/APP), an injection of OA cerebral stereotactic was administered to a SD rat in the hippocampal region, or PP-2A overexpressed plasmids was transfected transiently, the aggregate levels of APP phosphorylated APP, and APP-CTF were detected through immunoblotting and the activity of PP-2A and secretase was also detected using a reagent kit.

RESULT

The phosphorylation level of APP was significantly increased after the PP-2A activity was inhibited by OA. DES activated PP-2A or over-expressed PP-2A was able to reduce the phosphorylation level of APP. Either can inhibit PP and reduce the phosphorylation level of APP. The level of phosphorylated APP was increased significantly after the SD rat was injected with OA through the hippocampal region. The activity of β- and γ-secretases in N2a/APP cells significantly increased after OA treatment whereas the α-secretase activity had no significant changes; the Aβ level increased.

CONCLUSION

We discovered that PP-2A was capable of regulating the Aβ level by regulating APP phosphorylation level and β and γ-secretase activity(Fig. 5, Ref. 30).

Injectable and thermoresponsive self-assembled nanocomposite hydrogel for long-term anticancer drug delivery

The purpose of this study is to develop an injectable thermoresponsive hydrogel system that can undergo sol-gel phase transition by the stimulation of body temperature with improved mechanical stability and biocompatibility as a controlled drug delivery carrier for cancer therapy. Hexamethylene diisocyanate (HDI) was introduced into Pluronic F127 as a chain extender to improve the mechanical stability. HDI-Pluronic F127 copolymer was then incorporated with hyaluronic acid to develop a thermoresponsive nanocomposite hydrogel system. The physiochemical properties were characterized. The anticancer drug release profile and effect to inhibit tumor cells growth were analyzed in vitro and in vivo. The results showed that HDI-Pluronic F127/hyaluronic acid thermoresponsive hydrogel could undergo sol-gel transition as temperature increased to 37 °C. The nanocomposite polymer can spontaneously self-assemble into micellar structure with size of 100-200 nm. The release of doxorubicin (DOX) from HDI-PF127/HA composite hydrogel was a zero-order profile and maintained sustained release for over 28 days. The viability of tumor cells and size of tumor significantly decreased with incubation time, indicating the potential to have a therapeutic effect for cancer therapy. The injectable thermoresponsive nanocomposite hydrogel system was biocompatible and degradable and had the slow controlled release property for anticancer drugs with potential applications in the field of drug delivery.

Cell adhesion and proliferation enhancement by gelatin nanofiber scaffolds

Gelatin nanofibers (GNs) prepared by electrospinning were cross-linked with glutaraldehyde vapor to improve their water-resistant ability. After cross-linking treatment, the form of the fibers expressed no substantial change, but the average diameter of the fibers increased with increasing cross-linking time. The swelling induced by the moisture during the cross-linking process was moderated when the cross-linking time reached 45 min. The contact angle measurements confirmed that the electrospun gelatin fibers were more hydrophilic than the gelatin film (GF). Increasing the cross-linking time did not alter the hydrophilic properties of the gelatin fibers. The cell compatibility was evaluated based on 3-(4,5-dimethylthiazolyl)-2,5-diphenyltetrazolium bromide (MTT) assay, scanning electron microscope and confocal microscope observations, and Western blot analysis by culturing MG-63 cells on the GFs and GNs. The nanofibrous structure fabricated by an electrospinning technique was found to enhance cell adhesion and proliferation. This process is a cost-effective simulation of GN structures’ promising applications on scaffold preparation for tissue engineering.

Induction of the mitochondria apoptosis pathway by phytohemagglutinin erythroagglutinating in human lung cancer cells

BACKGROUND

Deregulation of apoptosis will influence the balance of cell proliferation and cell death, resulting in various fatal diseases that can include cancer. In prior research reports related to cancer therapy, phytohemagglutinin, a lectin extracted from red kidney beans, demonstrated the ability to inhibit the growth of human cancer cells. However, one of its isoforms, erythroagglutinating, has yet to be evaluated on its anticancer effects.

METHODS

PHA-E was used to induce apoptosis of A-549 lung cancer cells and the possible signal transduction pathway was elucidated, as measured by the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, G6PD release assay, flow cytometry, and Western blot analysis.

RESULTS

PHA-E treatment caused a dose-dependent increase of cell growth inhibition and cytotoxicity on A-549 cells. In annexin V/propidium iodide [i.e., PI] and TUNEL (terminal deoxynucleotidyl transferase dUTP nick-end labeling)/PI assay, we found that the rate of apoptotic cells was raised as the concentration of PHA-E increased. Treatment of A-549 cells with PHA-E resulted in enhancing the release of cytochrome c, which thus activated an increase in caspase 9 and caspase 3, the upregulation of Bax and Bad, the downregulation of Bcl-2 and phosphorylated Bad, and finally the inhibition of the epidermal growth factor receptor and its downstream signal pathway PI3K/Akt and MEK/ERK.

CONCLUSIONS

PHA-E can induce growth inhibition and cytotoxicity of lung cancer cells, which is mediated through an activation of the mitochondria apoptosis pathway. These results suggest that PHA-E can be developed into a new therapeutic treatment that can be applied as an effective anti-lung cancer drug in the near future.

Blocking effect of an immuno-suppressive agent, cynarin, on CD28 of T-cell receptor

PURPOSE

Cynarin, a potential immunosuppressant that blocks the interaction between the CD28 of T-cell receptor and CD80 of antigen presenting cells, was found in Echinacea purpurea by a new pharmaceutical screening method: After Flowing Through Immobilized Receptor (AFTIR; Dong et al., J Med Chem, 49: 1845-1854, 2006). This Echinacea component is the first small molecule that is able to specifically block "signal 2" of T-cell activation.

METHODS

In this study, we used the AFTIR method to further confirm that cynarin effectively blocked the binding between CD80 of B-cells and CD28 of T-cells, and provide details of its mechanism of action.

RESULTS

The experimental results showed that cynarin blocked about 87% of the CD28-dependent "signal 2" pathway of T-cell activation under the condition of one to one ratio of T-cell and B-cell in vitro. Theoretical structure modeling showed that cynarin binds to the "G-pocket" of CD28 (Evans et al., Nat Immunol, 6:271-279, 2005), and thus interrupts the site of interaction between CD28 and CD80.

CONCLUSIONS

These results confirm both that AFTIR is a promising method for screening selective active compounds from herbal medicine and that cynarin has great potential as an immuno-suppressive agent.

A novel bone substitute composite composed of tricalcium phosphate, gelatin and drynaria fortunei herbal extract

The Chinese herb, Gu-Sui-Bu (GSB) (Drynaria fortunei J. Sm.) has been anecdotally reported to enhance bone healing. We had previously confirmed in vitro the efficacy and safety of GSB in bone healing, and showed that it influenced both osteoblast and osteoclast activity. For clinically useful application of these bone regenerative effects, a satisfactory delivery system for GSB is required. In this study, we determined the optimal concentration of GSB for regenerative activity in rat bone cells via MTT, alkaline phosphatase (ALP), nodule formation and TRAP assays, and designed and tested a GSB-rich bone composite material. The composite was fabricated by mixing a biodegradable GGT composite, containing genipin cross-linked gelatin and tricalcium phosphate, with the predetermined concentration of GSB (GGT-GSB). Neonatal rat calvarial culture and animal implantation were employed to evaluate and compare in vitro and in vivo the potential of GGT-GSB and GGT in regeneration of defective bone tissue. The most effective concentration of GSB was 100 mug/mL, which significantly increased osteoblast numbers, intracellular ALP levels and nodule numbers, without influencing osteoclast activity. In vitro and in vivo tests also showed that GGT-GSB accelerated bone regeneration compared to GGT. GGT-GSB thus has great potential for improved bone repair.

Development of gelatin nanoparticles with biotinylated EGF conjugation for lung cancer targeting

Since lung cancer is the most malignant cancer today, a specific drug-delivery system has been developed for superior outcome. In this study, gelatin nanoparticles (GPs) employed as native carriers were grafted with NeutrAvidin(FITC) on the particle's surface (GP-Av). Next, the biotinylated epithelial growth factor (EGF) molecules were conjugated with NeutrAvidin(FITC), forming a core-shell-like structure (GP-Av-bEGF) to achieve the enhancement of targeting efficiency. These nanoparticles were applied as an EGF receptor (EGFR)-seeking agent to detect lung adenocarcinoma. The results showed that the modification process had no significant influence on particle size (220 nm) and zeta potential (-9.3 mV). By the in vitro cell culture test, GP-Av-bEGF resulted in higher entrance efficiency on adenocarcinoma cells (A549) than that on normal lung cells (HFL1) because A549 possessed greater amounts of EGFR. We also found that uptake of GP-Av-bEGF by A549 cells was time and dose dependent. Confocal microscopy confirmed the cellular internalization of GP-Av-bEGF, and more fluorescent spots of GP-Av-bEGF nanoparticles were obviously observed as well as lysosomal entrapment in A549. Finally, the delivery was demonstrated by in vivo aerosol administration to cancerous lung of the SCID mice model, and specific accumulation in cancerous lung was confirmed by image quantification. The targeting ability of GP-Av-bEGF was proved in vitro and in vivo, which holds promise for further anti-cancer drug applications.

Immuno-suppressive effect of blocking the CD28 signaling pathway in T-cells by an active component of Echinacea found by a novel pharmaceutical screening method

AFTIR (after flowing through immobilized receptor) is a novel method for screening herbal extracts for pharmaceutical properties. Using AFTIR, we identified Cynarin in Echinacea purpurea by its selective binding to chip immobilized CD28, a receptor of T-cells, which is instrumental to immune functioning. The results of surface plasma resonance show that binding between immobilized CD28 and Cynarin is stronger than the binding between CD28 and CD80, a co-stimulated receptor of antigen presenting cells. Cynarin's function was verified by its ability to downregulate CD28-dependent interleukin-2 (IL-2) expression in a T-cell culture line. AFTIR offers promise as an efficient screening method for herbal medicines.

Immobilization of Chinese herbal medicine onto the surface-modified calcium hydrogenphosphate

To accelerate the healing of bone defects or for healing to take place, it is often necessary to fill them with suitable substance. Various artificial materials defects have been developed. Among these, calcium phosphates and bioactive glass have been proven to be biocompatibile and bioactive materials that can chemically bond with bone, and have been successfully used clinically for repair of bone defects and augmentation of osseous tissue. However, those bioceramics have only the property of osteoconduction without any osteoinduction. Many ligands have been physicochemically absorbed onto substrates to enhance cell-substrate interactions. Although widely developed, they are still limited to use in long-term implantation because of their half-life period. Thus, some interfacial modification will be required for enhancing the efficacy of the delivery system. These models involve the immobilization of biologically active ligands of natural and synthetic origin onto various substrates to produce an interface with stronger chemical bond between ligand and substrate. The advantage of covalently immobilizing a ligand is that a chemical bond is present to prevent ligand or medicine from desorption. In our study, a two-step chemical immobilization was performed to surface-modified calcium hydrogenphosphate powders. The first was to modify the surface of calcium hydrogen-phosphate (CHP) with a coupling agent of hexanmethylene diisocyanate (HMDI). CHP surface modified by HMDI is abbreviated as MCHP. The linkage between CHP and HMDI will be characterized by FTIR. The second step was to immobilize chemically Gusuibu onto MCHP. Moreover, the sorption and desorption of Gusuibu was evaluated and quantitatively analyzed by spectrophotometer and HPLC. Bioceramic CHP was surface-modified by a two-step chemical immobilization. First, the surface of calcium hydrogen-phosphate (CHP) was successfully modified with coupling agent of hexanmethylene diisocyanate (HMDI). The first step was also activated the surface of CHP to induce primary amine terminator. The reaction of this functional group with Gusuibu was the second step. We confirmed simultaneously that Gusuibu could be immobilized chemically onto the surface of MCHP. Although some immobilized Gusuibu was also released rapidly at the first 12h, the degree of the released Gusuibu was lower than both by Gusuibu-adsorbing MCHP and Gusuibu-adsorbing CHP.

The effect of Gu-Sui-Bu (Drynaria fortunei J. Sm) immobilized modified calcium hydrogenphosphate on bone cell activities

In our previous study, we have validated the efficacy and the safety of Gu-Sui-Bu [Drynaria fortunei (Kunze) J. Sm.] by the bone cells culture. However, a satisfactory delivery system for Gu-Sui-Bu must be developed before it can be used in clinical medicine. In this study, we try to use modified calcium hydrogenphosphate (MCHP) bioceramic as a carrier to transport Gu-Sui-Bu into the bone cell culture system. Toward this goal, we evaluated the effect of a Gu-Sui-Bu-immobilized modified calcium hydrogenphosphate (GI-MCHP) on the bone cells activities. THE CHINESE MEDICINE: Gu-Sui-Bu [Drynaria fortunei (kunze) J. Sm] was extracted and then immobilized on the surface of MCHP. The rat osteoblasts-osteoclasts co-culture system was used as the experimental model. After the cells grew to 80% confluence, different sizes of GI-MCHP particles were tested. The mitochondria activity of the bone cells after exposure was determined by colorimetric assay. Biochemical markers such as lactate dehydrogenase (LDH), alkaline phosphatase (ALP), acid phosphatase (ACP) and prostaglandin E(2) titer were analyzed to evaluate the bone cells activities. Histomorphometric study of osteoclasts activities and the phenotype expression of osteoblasts were also evaluated. There is no detectable titer of LDH secretion into the medium and no significant change in the intracellular ALP content. The ALP titer in the culture medium did increase significantly at 3 days' culture, while there is a significant decrease in the intracellular ACP content and significant increase in the ACP titer in the medium. The concentrations of PGE(2) in tested medium are always significantly higher than that of control medium during the 7 days' culture. At the end of 7 days' culture, the PGE(2) concentrations in the tested medium were still 4.74 times that of the control medium. After GI-MCHP treatment on bone cells, the size of the osteoclasts seems decreased and their cell integrity seems lost, while the osteoblasts phenotype expression was relatively preserved. From this study, we demonstrated that Gu-Sui-Bu [Drynaria fortunei (Kunze) J. Sm.] immobilized MCHP has well preserved the potential beneficial effects of Gu-Sui-Bu on the bone cells culture.

The effect of Gu-Sui-Bu (Drynaria fortunei J. Sm) on bone cell activities

In the traditional Chinese medicine, Gu-Sui-Bu [Drynaria fortunei (kunze) J. Sm] has been reported as a good enhancer for bone healing. In this experiment, we investigate the biochemical effects of this traditional Chinese medicine on the bone cells culture. Different concentrations of crude extract of Gu-Sui-Bu were added to rat bone cells culture. The mitochondria activity of the bone cells after exposure was determined by colorimetric assay. Biochemical markers such as alkaline phosphatase (ALP), acid phosphatase (ACP) titer, prostaglandin E2 (PGE2) titer and the expression of both osteopontin and osteonectin mRNA were evaluated. The effect on the osteoclasts differentiation was evaluated by tartrate-resistant acid phosphatase (TRAP) stain. The most effective concentration of Gu-Sui-Bu on bone cells was 1 mg/ml. The addition of 1 mg/ml Gu-Sui-Bu to bone cells culture for 7 days can statistically increase the intracellular ALP amount; while the ACP and PGE2 amount in culture medium were significantly increased. In Northern blot analysis, the expression of both osteopontin and osteonectin mRNA were down-regulated after adding Gu-Sui-Bu into bone cells culture. The formation of multi-nucleated osteoclasts was more active than that of the control group, but no giant osteoclasts formation was observed. In this study, we demonstrated that Gu-Sui-Bu has potential effects on the bone cells culture. One of the major effects of Gu-Sui-Bu on the bone cells is probably mediated by its effect on the osteclasts activities. Continued and advanced study on the alterations in gene expression of bone cells by Chinese medicines will provide a basis for understanding the observed bone cell responses to various pharmacological interventions.

A study on grafting and characterization of HMDI-modified calcium hydrogenphosphate

It is known that the organic molecules can provide an effective means to manipulate the surface properties of the biodegradable ceramic. There are two ways to modify the surface of the biodegradable ceramic by organic molecules. The first one is through surface adsorption but organic molecules will easily be washed out in the physiological environment. The second approach is to graft organic molecules through covalent bond to the hydroxyl groups that are available on the surface of the ceramics. Isocyanate group has been reported as a coupling agent for hydroxyapatite and organic molecule. The studies showed that the isocyanate could react with hydroxyl groups of hydroxyapatite and form a covalent bond between isocyanate and hydroxyapatite. In the study, hexamethylene diisocyanate (HMDI) was used as coupling agent and calcium hydrogenphosphate (CaHPO4, CHP) was the candidate ceramic. CHP will react with HMDI at the temperature of 20 degrees C, 30 degrees C, 40 degrees C, 50 degrees C, 60 degrees C, and 70 degrees C for 4h. Dibutyltin dilaurate and hydroquinone were used as catalyst and inhibitor, respectively. The effect of reaction temperature on the grafted yield will be described. The linkage between CHP and HMDI will be characterized by DTA, TGA, FTIR, XRD, and 31P, 13C liquid state NMR. From the results, we successfully modified the surface of CHP with coupling agent of HMDI. The grafted yield of HMDI on CHP was increasing with the reaction temperature. The best temperature for CHP modified by HMDI is around 50 degrees C. The linkage between HMDI and the surface of CHP is a urethane linkage as CHP-O-CO-NH-(CH2)6-N=C=O. After further treatment, the terminal group of CHP treated with HMDI (MCHP) will be converted into a primary amine group as the formula of CHP-O-CO-NH-(CH2)6-NH2. If reaction temperature is 60 degrees C, long extension chain will occur with a urea linkage between the isocyanate groups as the formula of CHP-O-CO-NH-(CH2)6-(NH-CO-NH-(CH2)6)n-NH2. At reaction temperature higher than 60 degrees C, the HMDI will become prepolymerized forms in solution. The prepolymerized forms such as allophanate, biuret, uretidione and urea linkage will turn the solution into gel type mixture, which will lead to low grafted yield of HMDI on CHP. When MCHP prepared at the temperature 20 degrees C, there is no evidence of long extension but the grafted yield is the lowest only 0.9 wt% around.

Preparation and characterization of surface-modified calcium hydrogenphosphate by hexamethylene diisocyanates

Isocyanate group has been reported as a coupling agent of hydroxyapatite and polymers. The studies showed that the isocyanate would react with hydroxyl groups of hydroxyapatite and form a covalent bond between isocyanate and hydroxyapatite. In the study, hexamethlene diisocyanate (HMDI) was used as coupling agent. Calcium hydrogen-phosphate (CaHPO4, CHP) powders was the candidate ceramic due to higher content of hydroxyl group, which would react with HMDI at the temperature of 30, 40, 50, 60, and 70 degrees C for 4 hours. Dibutyltin dilaurate and hydroquinone were used as catalyst and inhibitor, respectively. The product was analyzed by DTA, TGA, FTIR, XRD, 13C solid state NMR and 31P, 13C liquid state NMR. From the results, we could prove the surface of calcium hydrogen-phosphate has been successfully modified. The largest amount (5.6 wt%) of HMDI could be grafted on the surface of CHP when reacted at 50 degrees C for 4 hours. Some chain extension could be observed and their structure would also be described in the research.