Thiourea leaching gold and silver from the printed circuit boards of waste mobile phones.

The present communication deals with the leaching of gold and silver from the printed circuit boards (PCBs) of waste mobile phones using an effective and less hazardous system, i.e., a thiourea leaching process as an alternative to the conventional and toxic cyanide leaching of gold. The influence of particle size, thiourea and Fe(3+) concentrations and temperature on the leaching of gold and silver from waste mobile phones was investigated. Gold extraction was found to be enhanced in a PCBs particle size of 100 mesh with the solutions containing 24 g/L thiourea and Fe(3+) concentration of 0.6% under the room temperature. In this case, about 90% of gold and 50% of silver were leached by the reaction of 2h. The obtained data will be useful for the development of processes for the recycling of gold and silver from the PCBs of waste mobile phones.

Induction of virus-neutralizing antibodies and T cell responses by dengue virus type 1 virus-like particles prepared from Pichia pastoris / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Dengue is currently a significant global health problem but no vaccines are available against the four dengue serotypes virus infections. The development of safe and effective vaccines has been hampered by the requirement of conferring complete protection against all four dengue serotypes and the lack of a convenient animal model. Virus-like particles (VLPs) have emerged as a promising subunit vaccine candidate. One strategy of vaccine development is to produce a tetravalent dengue subunit vaccine by mixing recombinant VLPs, corresponding to all four dengue virus serotypes. Towards this end, this study aimed to establish a Pichia pastoris (P. pastoris) expression system for production of dengue virus type 1 (DENV-1) VLPs and evaluate the humoral and cellular immune response of this particle in mice.</p><p><b>METHODS</b>A recombinant yeast P. pastoris clone containing prM and E genes of DENV-1 was constructed and DENV-1 VLPs expressed by this clone were analyzed by sucrose density gradient centrifugation, Western blotting, and transmission electron microscope. Groups of mice were immunized by these particles plus adjuvant formulations, then mice were tested by ELISA and neutralization assay for humoral immune response, and by lymphocyte proliferation and cytokine production assays for a cellular immune response.</p><p><b>RESULTS</b>Our data demonstrated that recombinant DENV-1 VLPs consisting of prM and E protein were successfully expressed in the yeast P. pastoris. Sera of VLPs immunized mice were shown to contain a high-titer of antibodies and the neutralization assay suggested that those antibodies neutralized virus infection in vitro. Data from the T lymphocyte proliferation assay showed proliferation of T cell, and ELISA found elevated secretion levels of interferon IFN-γ and IL-4.</p><p><b>CONCLUSIONS</b>P. pastoris-expressed DENV-1 VLPs can induce virus neutralizing antibodies and T cell responses in immunized mice. Using P. pastoris to produce VLPs offers a promising and economic strategy for dengue virus vaccine development.</p>

Establishment and characterization of dengue virus type 2 nonstructural protein 1 specific T cell lines.

Immunity against dengue viruses (DENV) infection may include cellular immune responses which involve in the immunopathology of DENV infection hosts. This study was to establish short-term dengue virus type 2 (DENV2) nonstructural protein 1 (NS1) specific T cells from splenocytes from BALB/c mice immunized with DENV2 NS1 in vitro, which may be used to identify immunopathologic mechanism of dengue. Nine DENV2 NS1 specific T cell lines were successfully established by using limiting dilution methods and maintained for 20 weeks by re-stimulated with DENV2 NS1, recombinant mouse IL-2 and antigen presenting cell weekly. Phenotypically, these cells were mainly composed of CD3(+)CD4(+) T cells. The culture supernatants of these cells contained large amounts of TNF-α and IFN-γ. Vascular tissue pathological change could be found in the mice adoptive transferred with DENV2 NS1 specific T cells. The results indicate that DENV2 NS1 specific T cells could be established and maintained with syngeneic T cell growth factors in vitro. Meanwhile, DENV2 NS1 specific T cells might contribute to the immunopathology of vascular leakage of dengue.

The relationships among HBV genotypes, HBV DNA levels and histopathological features in the livers of familial grouped hepatitis B patients in the Tianjin area / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To analyse the relationships among HBV genotypes, HBV DNA levels and histopathological features of the livers of familial grouped hepatitis B patients in the Tianjin area.</p><p><b>METHODS</b>One hundred familial grouped hepatitis B (CHB) patients were enrolled in this study. Thirty-five of the 100 patients were chronic asymptomatic HBsAg carriers (ASC) and 65/100 were mild CHB patients. Their HBV genotypes and HBV-DNA levels were detected and liver biopsies were performed for analyzing the pathological features.</p><p><b>RESULTS</b>Seven patients were of HBV genotype B (7%), and most of them had a HBV DNA level in the middle 10(3-5) copies/ml (57.14%). The histopathological features of the livers were of different degrees of injury. Eleven patients HBV was of genotype BC (11%); their HBV DNA levels were from 10(3-5) copies/ml (45.45%) to 10(6-7)copies/ml (36.36%). Their liver pathology showed slight or severe injuries (< or = G2 90.91%, < or = S(2) 81.82%). Eighty-two patients HBV was of genotype C (82%), and among the 82, 29 were ASC and 53 were CHB. Among the ASC, most of them had a high HBV DNA level (72.41%), and all of them had different degrees of liver injury. Among the CHB, their HBV DNA levels were 10(6-7) copies/ml (39.62%) and more than or equal 10(8) copies/ml (49.06%). The liver histopathological features were > or = G(2) in 38 patients (71.70%), and > or = S(2) in 25 patients (47.17%).</p><p><b>CONCLUSIONS</b>(1) In the majority, HBV of the family gathered hepatitis B patients living in Tianjin is of genotype C and they have a high HBV-DNA level and severe liver pathological injuries. These features of the family gathered hepatitis B patients are the main factors causing the unfavorable prognosis of the patients. (2) There is inflammation of different degrees in the livers and high HBV DNA levels in all the family gathered ASC patients. Antiviral therapy should be planned according to the pathological features in patients livers. (3) Liver biopsies should be performed routinely before their antiviral therapy.</p>