A green and facile synthesis for rGO/Ag nanocomposites using one-step chemical co-reduction route at ambient temperature and combined first principles theoretical analyze.

Recently, graphene decorated with various inorganic nanoparticles, such as Pt, Au, Ag, TiO2 and Fe3O4, among which Ag nanocomposites are good candidates for electronics, optics, electrochemistry and catalysis. However, preparation techniques for Ag nanoparticles/carbon matrix hybrids require tedious multi-step processes often involving toxic reducing agents/high temperatures which is not viable for scalable production. Here, a facile, one step and eco-friendly chemical co-reduction route was utilized to synthesis of a new nanocomposites by Ag nanoparticle anchored on reduced graphene oxide (rGO) at ambient temperature and combined first principles theoretical analyze their interfacial adsorption behavior, is reported. In this way, graphene oxide (GO) and Ag+ simultaneously reduced by thiourea dioxide (TD) without using any additional reduced reactants. Results indicated that GO was successfully reduced to rGO and well-dispersed Ag nanoparticles with sizes of 6-7 nm, anchored on the surface of rGO sheets. Reduction mechanism was attributed to the synergistic effect of its hydrolysis products in aqueous media. The experiment and theoretical calculation results obtained demonstrate this method to be applicable to the synthesis of other metals on rGO sheets in order to improve wettability and interfacial bonding between rGO and metal and may possibly find various forthcoming medicinal, industrial and technological applications.

Implantation of bone marrow-derived buffy coat can supplement bone marrow stimulation for articular cartilage repair.

OBJECTIVE: Bone marrow stimulation (BMS) has been regarded as a first line procedure for repair of articular cartilage. However, repaired cartilage from BMS is known to be unlike that of hyaline cartilage and its inner endurance is not guaranteed. The reason presumably came from a shortage of cartilage-forming cells in blood clots derived by BMS. In order to increase repairable cellularity, the feasibility of autologous bone marrow-derived buffy coat transplantation in repair of large full-thickness cartilage defects was investigated in this study. METHODS: Rabbits were divided into four groups: the defect remained untreated as a negative control; performance of BMS only (BMS group); BMS followed by supplementation of autologous bone marrow buffy coat (Buffy coat group); transplantation of autologous osteochondral transplantation (AOTS) as a positive control. RESULTS: Repair of cartilage defects in the Buffy coat group in a rabbit model was more effective than BMS alone and similar to AOTS. Gross findings, histological analysis, histological scoring, immunohistochemistry, and chemical assay demonstrated that supplementation of autologous bone marrow buffy coat after BMS arthroplasty effectively repaired cartilage defects in a rabbit model, and was more effective than BMS arthroplasty alone. CONCLUSION: Supplementation of autologous bone marrow-derived buffy coat in cases of BMS could be a useful clinical protocol for cartilage repair.

Passive transfer of experimental autoimmune neuritis by IL-12 and IL-18 synergistically potentiated lymphoid cells is regulated by NKR-P1+ cells.

The aim of this study was to investigate the roles and mechanism of interleukin-12 (IL-12) and interleukin-18 (IL-18) in potentiating the autoreactivity of lymphoid cells specific for P2 53-78 peptide. P2 53-78-specific lymphoid cells in the presence of IL-12 or IL-18 alone passive transferred only moderate experimental autoimmune neuritis (EAN) into a low percentage of recipients. However, lymphoid cells co-cultured with both cytokines transferred aggressive clinical and histological EAN into all recipients. NKR-P1+ cells (including NK and NKT cells) played an immunosuppressive function in passive transfer EAN and depletion of NKR-P1+ cells by anti-NKR-P1 Ab and complement induced a more serious form of EAN. Nevertheless, lymphoid cells co-cultured with both IL-12 and IL-18 induced high levels of interferon-gamma (IFN-gamma) and promoted Th1 differentiation partially through NKR-P1+ cells and to some extent, NKR-P1+ cell depletion inhibited the auto-reactivity of lymphoid cells treated with IL-12 and IL-18.

Transduction of human catalase mediated by an HIV-1 TAT protein basic domain and arginine-rich peptides into mammalian cells.

Antioxidant enzymes such as superoxide dismutase (SOD) and catalase (CAT) have been considered to have a beneficial effect against various diseases mediated by reactive oxygen species (ROS). Although a variety of modified recombinant antioxidant enzymes have been generated to protect against the oxidative stresses, the lack of their transduction ability into cells resulted in limited ability to detoxify intracellular ROS. To render the catalase enzyme capable of detoxifying intracellular ROS when added extracellularly, cell-permeable recombinant catalase proteins were generated. A human liver catalase gene was cloned and fused with a gene fragment encoding the HIV-1 Tat protein transduction domain (RKKRRQRRR) and arginine-rich peptides (RRRRRRRRR) in a bacterial expression vector to produce genetic in-frame Tat-CAT and 9Arg-CAT fusion proteins, respectively. The expressed and purified fusion proteins can be transduced into mammalian cells (HeLa and PC12 cells) in a time- and dose-dependent manner when added exogenously in culture medium, and transduced fusion proteins were enzymatically active and stable for 60 h. When exposed to H(2)O(2), the viability of HeLa cells transduced with Tat-CAT or 9Arg-CAT fusion proteins was significantly increased. In combination with transduced SOD, transduced catalase also resulted in a cooperative increase in cell viability when the cells were treated with paraquat, an intracellular antioxide anion generator. We then evaluated the ability of the catalase fusion proteins to transduce into animal skin. This analysis showed that Tat-CAT and 9Arg-CAT fusion proteins efficiently penetrated the epidermis as well as the dermis of the subcutaneous layer when sprayed on animal skin, as judged by immunohistochemistry and specific enzyme activities. These results suggest that Tat-CAT and 9Arg-CAT fusion proteins can be used in protein therapy for various disorders related to this antioxidant enzyme.

Brain succinic semialdehyde dehydrogenase: identification of reactive lysyl residues labeled with pyridoxal-5'-phosphate.

An NAD+ dependent succinic semialdehyde dehydrogenase from bovine brain was inactivated by pyridoxal-5'- phosphate. Spectral evidence is presented to indicate that the inactivation proceeds through formation of a Schiff's base with amino groups of the enzyme. After NaBH(4) reduction of the pyridoxal-5'-phosphate inactivated enzyme, it was observed that 3.8 mol phosphopyridoxyl residues were incorporated/enzyme tetramer. The coenzyme, NAD+, protected the enzyme against inactivation by pyridoxal-5'-phosphate. The absorption spectrum of the reduced and dialyzed pyridoxal-5'-phosphate-inactivated enzyme showed a characteristic peak at 325 nm, which was absent in the spectrum of the native enzyme. The fluorescence spectrum of the pyridoxyl enzyme differs completely from that of the native enzyme. After tryptic digestion of the enzyme modified with pyridoxal-5'-phosphate followed by [3H]NaBH4 reduction, a radioactive peptide absorbing at 210 nm was isolated by reverse-phase HPLC. The sequences of the peptide containing the phosphopyridoxyllysine were clearly identical to sequences of other mammalian succinic semialdehyde dehydrogenase brain species including human. It is suggested that the catalytic function of succinic semialdehyde dehydrogenase is modulated by binding of pyridoxal-5'-phosphate to specific Lys(347) residue at or near the coenzyme-binding site of the protein.

Transduction of Cu,Zn-superoxide dismutase mediated by an HIV-1 Tat protein basic domain into mammalian cells.

A human Cu,Zn-superoxide dismutase (Cu,Zn-SOD) gene was fused with a gene fragment encoding the nine amino acid transactivator of transcription (Tat) protein transduction domain (RKKRRQRRR) of HIV-1 in a bacterial expression vector to produce a genetic in-frame Tat-SOD fusion protein. The expressed and purified Tat-SOD fusion protein in Escherichia coli can enter HeLa cells in a time- and dose-dependent manner when added exogenously in a culture media. Denatured Tat-SOD protein was transduced much more efficiently into cells than were native proteins. Once inside the cells, transduced Tat-SOD protein was enzymatically active and stable for 24 h. The cell viability of HeLa cells treated with paraquat, an intracellular superoxide anion generator, was increased by transduced Tat-SOD. These lines of results suggest that the transduction of Tat-SOD fusion protein may be one of the ways to replenish the Cu,Zn-SOD in the various disorders related to this antioxidant enzyme.

[Dynamic study on blood lead levels of pregnant women and infants in a district of Beijing].

Under strict quality control, the authors investigated the levels of PbB among 270 women from early pregnancy to delivery and their infants. The mean PbB levels of the first three months of pregnancy and delivery is 45.0 microg/L and 64.8 microg/L respectively. Analysis shows an increase of mean PbB level in the period of gestation, and a significant increase in the last three months. The mean PbB level of umbilical cord is 51.9 microg/L (10.4% umbilical cord PbB > 100 microg/L). The mean PbB level of infants increases with the months, it increases significantly after six months. Regression analysis confirmed the positive correlation between the PbB levels of first three and second three months of gestation, the PbB of delivery and umbilical cord, the PbB of umbilical coral and infants. The correlation coefficient of the PbB level of delivery and umbilical cord, the PbB level of infants at six months and at twelve months is 0.80 and 0.47 respectively.

Protection against airsacculitis with sequential systemic and local immunization of chickens using killed Mycoplasma gallisepticum bacterin with iota carrageenan adjuvant.

The induction of protective immunity to Mycoplasma gallisepticum (MG) by bacterins containing 0.2% iota carrageenan (iCGN) as an adjuvant has been studied. Various combinations of intracoelomic (i.c.), intratracheal (i.t.), intranasal (i.n.), intravenous (i.v.), subcutaneous (s.c.) and oral immunization routes were evaluated. Vaccinated and non-vaccinated groups were compared with a group vaccinated s.c. with a commercial bacterin. Primary i.c. immunization with the bacterin was as effective as commercial bacterin and was more effective when followed by i.n. or i.t. immunization. Oral immunization was ineffective, in contrast to observations reported with mice. The i.c./i.n. and i.c./i.t. combinations were the most effective, produced the highest levels of anti-MG IgG and IgA in serum and tracheobronchial washes, and sometimes provided 100% protection against air sac lesions. Chickens vaccinated by the i.c./i.n. or i.c./i.t. routes had the fewest virulent organisms in their respiratory tract secretions. These results demonstrated that i.c. immunization followed by local immunization with the bacterin is most efficacious in protecting chickens against airsacculitis.

Collagen fibril structure of normal, aging, and osteoarthritic cartilage.

The collagen architecture in normal, aging, and osteoarthritic articular cartilage was studied optically using a new silver staining technique based on specimens from 50 autopsy cases, four amputated limbs, and six osteoarthritic knees. In the normal articular cartilage, the collagen fibrils in the superficial zone were compactly arranged into layers of decussating flat ribbons mostly parallel to the artificial split lines. The fibrils showed a tendency to condense into vertical arcade columns undergirded by tangential bundles in the intermediate zone. In the deep zone, the fibrils formed a random meshwork with a slight preponderance of vertical fibrils in the perilacunar region. Three types of early degradative lesions involving the collagen network were identified. Type I lesions consisted of focal superficial disruptions related to age and friction. Type II lesions consisted of focal disruptions of tangential fibrils in the intermediate zone leading to cyst formation, probably representing a form of local stress failure. Type III lesions were found in the patella and consisted of marked swelling of the superficial zone, the cause of which was unknown. Lesions of varying severity were seen within each of the three types; the morphological changes of the more severe lesions overlapped with those of clinically overt osteoarthritis.

Sequential intracoelomic and intrabursal immunization of chickens with inactivated Mycoplasma gallisepticum bacterin and iota carrageenan adjuvant.

Chickens immunized by sequential intracoelomic (analogous to intraperitoneal route in mammals) and intrabursal (i.c./i.b.) routes with inactivated Mycoplasma gallisepticum (MG) bacterin mixed with 0.2% iota carrageenan (iCGN) as an adjuvant were resistant to airsacculitis induced by a subsequent aerosol challenge with virulent R strain MG. In contrast, immunization by the i.c./i.b. routes with inactivated bacterin without the adjuvant or with 0.2% iCGN did not confer significant protection. Chickens immunized by the i.c./i.b. routes with the adjuvanted bacterin had increased levels of circulating and local anti-MG IgG but not IgM or IgA. Tracheal populations of MG were reduced when compared with unimmunized controls.