Rapid one-step derivatization of Se(VI) to a piazselenol for the spectrofluorimetric determination of selenium in biological material

A spectrofluorimetric method for the determination of total selenium in biological samples has been developed. After oxidative destruction, the sample is reacted with a mixture of bromide and 2,3-diamino-1,4-dibromonaphthalene (Br(2)-DAN) without pH adjustment. Selenium(VI) is rapidly reduced by bromide to Se(IV) which then forms 4,7-dibromo-5,6-benzopiazselenol (Br(2)-DAN-Se). The conversion of Se(VI) to Br(2)-DAN-Se is completed in 6 min at 100 degrees C. The piazselenol is extracted to cyclohexane and the fluorescence measured at 577 nm with excitation at 518 nm. The procedure has been validated by determinations on reference materials with selenium concentrations ranging from 4 to 1460 ng g(-1). The advantages of the method are the fast reduction of Se(VI) by hydrobromic acid and the properties of Br(2)-DAN, which permit the piazselenol formation to be carried out in a strongly acidic medium and at high temperature. The limit of detection is 0.6 ng g(-1) as estimated by three times the standard deviation of the blank determination (n = 7). The rate of reduction of Se(VI) to Se(IV) in hydrobromic acid was investigated as a function of concentration and temperature. The new kinetic data together with previous kinetic and equilibrium data for the piazselenol formation were used to model and optimize the simultaneous reduction-derivatization procedure.

The soluble tachyzoite antigen of Toxoplasma gondii has a protective effect on mouse allografts

BACKGROUND

Infection with some types of parasites can significantly prolong allograft survival in mice. It is unknown whether the soluble tachyzoite antigen (STAg) from Toxoplasma gondii has the same effect and by what mechanism it acts.

METHODS

A mouse model of cardiac and skin allograft transplantation was established between BALB/c (H-2(d)) and C57BL/6(H-2(b)) mice. T gondii STAg was prepared, and 5 μg was administered subcutaneously to recipient mice 4 days before transplantation. The graft status was checked daily, and histologic and immunohistochemical assays were used to evaluate rejection. The serum cytokine levels from the recipient mice were analyzed by Luminex.

RESULT

The administration of 5 μg STAg 4 days before transplantation significantly prolonged the survival time of the heart and skin allografts to 85.17 ± 14.06 and 24.17 ± 2.32 days, respectively. Immunohistochemical staining showed that the CD4(+) and CD8(+) T lymphocytes were markedly reduced in the allografts at day 7 posttransplantation. Notably, interleukin (IL)-12, IL-2, and IL-17 levels were significantly reduced in the serum of mice treated with STAg compared with untreated mice 7 days after transplantation. In contrast, the levels of the antiinflammatory cytokine IL-10 were elevated.

CONCLUSION

A single administration of STAg before transplantation can significantly prolong the allograft survival time, which is accompanied by impaired lymphocyte infiltration and a reduced Th1 response.

Blocking p55PIK signaling inhibits proliferation and induces differentiation of leukemia cells

p55PIK, a regulatory subunit of phosphatidylinositol 3-kinases, promotes cell cycle progression by interacting with cell cycle modulators such as retinoblastoma protein (Rb) via its unique amino-terminal 24 amino-acid residue (N24). Overexpression of N24 specifically inhibits these interactions and leads to cell cycle arrest. Herein, we describe the generation of a fusion protein (Tat transactivator protein (TAT)-N24) that contains the protein transduction domain and N24, and examined its effects on the proliferation and differentiation of leukemia cells. TAT-N24 not only blocks cell proliferation but remarkably induces differentiation of leukemia cells in vitro and in vivo. Systemically administered TAT-N24 also significantly decreases growth of leukemia cell tumors in animal models. Furthermore, overexpression of p55PIK in leukemia cells leads to increased proliferation; however, TAT-N24 blocks this effect and concomitantly induces differentiation. There is significant upregulation of p55PIK mRNA and protein expression in leukemia cells from patients. TAT-N24 inhibits cell cycle progression and induces differentiation of bone marrow cells derived from patients with several different types of leukemia. These results show that cell-permeable N24 peptide induces leukemia cell differentiation and suggest that p55PIK may be a novel drug target for the treatment of hematopoetic malignancies.

Directed flow of identified particles in Au+Au collisions at √[SNN]=200 GeV at RHIC

STAR's measurements of directed flow (v1) around midrapidity for π±, K±, KS0, p, and p[over ¯] in Au+Au collisions at √[sNN]=200  GeV are presented. A negative v1(y) slope is observed for most of produced particles (π±, K±, KS0, and p[over ¯]). In 5%-30% central collisions, a sizable difference is present between the v1(y) slope of protons and antiprotons, with the former being consistent with zero within errors. The v1 excitation function is presented. Comparisons to model calculations (RQMD, UrQMD, AMPT, QGSM with parton recombination, and a hydrodynamics model with a tilted source) are made. For those models which have calculations of v1 for both pions and protons, none of them can describe v1(y) for pions and protons simultaneously. The hydrodynamics model with a tilted source as currently implemented cannot explain the centrality dependence of the difference between the v1(y) slopes of protons and antiprotons.

Low dose IR-induced IGF-1-sCLU expression: a p53-repressed expression cascade that interferes with TGFβ1 signaling to confer a pro-survival bystander effect

Inadvertent mammalian tissue exposures to low doses of ionizing radiation (IR) after radiation accidents, remediation of radioactive-contaminated areas, space travel or a dirty bomb represent an interesting trauma to an organism. Possible low-dose IR-induced bystander effects could impact our evaluation of human health effects, as cells within tissue are not equally damaged after doses of IR ≤10 cGy. To understand tissue responses after low IR doses, we generated a reporter system using the human clusterin promoter fused to firefly luciferase (hCLUp-Luc). Secretory clusterin (sCLU), an extracellular molecular chaperone, induced by low doses of cytotoxic agents, clears cell debris. Low-dose IR (≥2 cGy) exposure induced hCLUp-Luc activity with peak levels at 96 h, consistent with endogenous sCLU levels. As doses increased (≥1 Gy), sCLU induction amplitudes increased and time-to-peak response decreased. sCLU expression was stimulated by insulin-like growth factor-1, but suppressed by p53. Responses in transgenic hCLUp-Luc reporter mice after low IR doses showed that specific tissues (that is, colon, spleen, mammary, thymus and bone marrow) of female mice induced hCLUp-Luc activity more than male mice after whole body (≥10 cGy) irradiation. Tissue-specific, non-linear dose- and time-responses of hCLUp-Luc and endogenous sCLU levels were noted. Colon maintained homeostatic balance after 10 cGy. Bone marrow responded with delayed, but prolonged and elevated expression. Intraperitoneal administration of α-transforming growth factor (TGF)β1 (1D11), but not control (13C4) antibodies, immediately following IR exposure abrogated CLU induction responses. Induction in vivo also correlated with Smad signaling by activated TGFβ1 after IR. Mechanistically, media with elevated sCLU levels suppressed signaling, blocked apoptosis and increased survival of TGFβ1-exposed tumor or normal cells. Thus, sCLU is a pro-survival bystander factor that abrogates TGFβ1 signaling and most likely promotes wound healing.

Identified hadron compositions in p+p and Au+Au collisions at high transverse momenta at √S(NN)=200 GeV

We report transverse momentum (p(T)≤15  GeV/c) spectra of π(±), K(±), p, p[over ¯], K(S)(0), and ρ(0) at midrapidity in p+p and Au+Au collisions at √S(NN)=200  GeV. Perturbative QCD calculations are consistent with π(±) spectra in p+p collisions but do not reproduce K and p(p[over ¯]) spectra. The observed decreasing antiparticle-to-particle ratios with increasing p(T) provide experimental evidence for varying quark and gluon jet contributions to high-p(T) hadron yields. The relative hadron abundances in Au+Au at p(T)≳8  GeV/c are measured to be similar to the p+p results, despite the expected Casimir effect for parton energy loss.

Strangeness enhancement in Cu-Cu and Au-Au collisions at √S(NN)=200 GeV

We report new STAR measurements of midrapidity yields for the Λ, Λ[over ¯], K(S)(0), Ξ(-), Ξ[over ¯](+), Ω(-), Ω[over ¯](+) particles in Cu+Cu collisions at √S(NN)==200  GeV, and midrapidity yields for the Λ, Λ[over ¯], K(S)(0) particles in Au+Au at √S(NN)==200  GeV. We show that, at a given number of participating nucleons, the production of strange hadrons is higher in Cu+Cu collisions than in Au+Au collisions at the same center-of-mass energy. We find that aspects of the enhancement factors for all particles can be described by a parametrization based on the fraction of participants that undergo multiple collisions.

CMRI based 3D left ventricle motion analysis on patients with acute myocardial infarction

3D Quantitative measurement of left ventricle (LV) motion on patients with acute myocardial infarction has been recognized as essential for effective LV function diagnosis. This paper presents a method to quantify 3D LV motion obtained from conventional CINE MRI using image analysis based on mathematical modeling. Level set method is employed for segmentation, and a 3D LV geometry was reconstructed by co-registering different views of MRI images. A mathematical model of LV geometry was then constructed to quantitatively describe the LV wall inward motion. The results using real data show that the method is able to quantify the LV inward motion, and can clearly represent the changed motion pattern with the follow-up data. Furthermore, the LV motion analysis for 8 patients with acute myocardial infarction (MI) show that high inward motion occurs mainly in the basal region of LV while a negative relation is found between LV ejection fraction (EF) improvement after acute MI and solely basal region inward motion, which could be helpful for diagnosis and LV EF recovery prediction.

Analysis of altered proteins related to blast crisis in chronic myeloid leukemia by proteomic study

INTRODUCTION

Chromic myeloid leukemia (CML) blast crisis (BC) and imatinib (IM) resistance is a significant barrier to the effective treatment of the disease.

METHODS

Expression profiles of differential proteins were identified, and new biomarkers or pathways related to BC in CML were screened through proteomic analysis. Total proteins from primary bone marrow cells of CML patients in chronic phase (CP) and BC were separated via two-dimensional (2D) polyacrylamide gel electrophoresis and then analyzed by imagemaster 5.0 software to detect differential protein spots which were already identified by mass spectrometry. Based on the variation of the whole expression profile, some key proteins were picked out for Western blot to confirm the accuracy of proteomics data. Moreover, related signal pathways involving those proteins were investigated.

RESULTS

The result indicated that thirteen protein points between CML-CP and CML-BC were successfully determined. Results from Western blot of RhoA, hnRNPK, ANXA1, PSMB4, and LTA4H were similar to those from 2D polyacrylamide gel electrophoresis. Most of those proteins were involved in the proteosome pathway and the small G-protein pathway.

CONCLUSION

A group of proteins associated with BC can be obtained and the result of this study might provide clues for further research.

Toxin composition and toxicity dynamics of marine gastropod Nassarius spp. collected from Lianyungang, China

Consumption of nassariid gastropods often leads to poisoning incidents in some coastal provinces in China. To elucidate the pattern of toxicity dynamics and origin of toxins, samples of gastropod Nassarius spp. were collected from late May to early August 2007 from Lianyungang, Jiangsu province, where the poisoning incidents have been frequently reported. Toxicity was first screened with the mouse bioassay method, and tetrodotoxin and its analogues (TTXs) were analysed with high-performance liquid chromatography coupled with an ion-trap mass spectrometer (HPLC-MS(n)). The toxicity of nassariid N. semiplicatus showed an 'M'-shaped pattern of fluctuation during the sampling season. Two peaks of toxicity appeared in late May and late July. The maximum toxicity was recorded on 24 May, with the value of 846 mouse unit (MU) g(-1) of tissue (wet weight). TTX and its analogues trideoxyTTX, 4-epiTTX, anhydroTTX and oxoTTX were detected in the nassariid samples. TrideoxyTTX but not TTX was the major toxin in all the samples. No paralytic shellfish poison (PSP) was detected in the sample with the maximum toxicity by HPLC-FLD analysis. Variation of TTX content in the tissue of nassariid gastropods correlates well with the dynamics of toxicity. It is suggested that TTXs are the major toxins corresponding to the toxicity of the nassariids, and May and July are the high-risk seasons for consumption of nassariids, which is critical for the management of poisoning incidents.