Dynamic changes of the ecological environment quality in a river basin: a case study of the main stream of Songhua river basin

This paper reports the investigation and analysis of the status and dynamic changes of ecological environment quality in the main stream of Songhua river basin. The evaluation index system was established and the eco-environment quality in the year of 2000 and 2008 was studied in depth. Based on our research, the trend of dynamic changes of the eco-environment quality and its origins have been further discussed: In the year of 2000, the range of evaluation index covered from 0.31 to 0.47. Harbin and Yichun was relatively better than the rest of study areas. In the year of 2008, except districts of Daqing and Qitaihe, the environmental quality of Songhua river basin has entirely improved, wherein the evaluation index of the eco-environment covered from 0.31 to 0.57. Particularly, the eco-environment quality of Hegang and Shuangyashan has obtained significant improvement, whereas the improvement of Jiamusi was not obvious. According to the evaluation results, the environmental quality in the study area has an upward trend with the average growth rate 0.13% per year.

Comparison of Disulfide Contents and Solubility at Alkaline pH of Insecticidal and Noninsecticidal Bacillus thuringiensis Protein Crystals

We compared two insecticidal and eight noninsecticidal soil isolates of Bacillus thuringiensis with regard to the solubility of their proteinaceous crystals at alkaline pH values. The protein disulfide contents of the insecticidal and noninsecticidal crystals were equivalent. However, six of the noninsecticidal crystals were soluble only at pH values of >/=12. This lack of solubility contributed to their lack of toxicity. One crystal type which was soluble only at pH >/=12 (strain SHP 1-12) did exhibit significant toxicity to tobacco hornworm larvae when the crystals were presolubilized. In contrast, freshly prepared crystals from the highly insecticidal strain HD-1 were solubilized at pH 9.5 to 10.5, but when these crystals were denatured, by either 8 M urea or autoclave temperatures, they became nontoxic and were soluble only at pH values of >/=12. These changes in toxicity and solubility occurred even though the denatured HD-1 crystals were morphologically indistinguishable from native crystals. Our data are consistent with the view that insecticidal crystals contain distorted, destabilized disulfide bonds which allow them to be solubilized at pH values (9.5 to 10.5) characteristic of lepidopteran and dipteran larval midguts.

Bacillus thuringiensis HD-73 Spores Have Surface-Localized Cry1Ac Toxin: Physiological and Pathogenic Consequences

Spores from Cry(sup+) strains of Bacillus thuringiensis bound fluorescein isothiocyanate-labeled antibodies specific for the 65-kDa activated Cry 1Ac toxin, whereas spores from Bacillus cereus and Cry(sup-) strains of B. thuringiensis did not. The Cry(sup+) spores could be activated for germination by alkaline conditions (pH 10.3), whereas Cry(sup-) spores could not. Once the surrounding exosporia had been removed or permeabilized, Cry(sup+) spores were able to bind the toxin receptor(s) from insect gut brush border membrane vesicle preparations, and their germination rates were increased ca. threefold in the presence of brush border membrane vesicles. A model is presented whereby in the soil the Cry toxins on the spore surface are protected by the exosporium while in the gut they are exposed and available for binding to the insect receptors. This model explains why the disulfide-rich C terminus of the cry genes is so highly conserved even though it is removed during the processing of the protoxin to the activated toxin. It also highlights the trade-off resulting from having Cry toxins located on the spore surface, i.e., decreased spore resistance versus enhanced insect pathogenesis.

Enamel proteases reduce amelogenin-apatite binding

Organic matrix degradation and crystal maturation are extracellular events that occur simultaneously during enamel biomineralization. We hypothesized that enamel proteases control amelogenin-mineral interaction, which, in turn can affect crystal nucleation, organization, and growth. We used a recombinant amelogenin (rP172), a homolog of its major cleavage product (rP148), and a native amelogenin lacking both N- and C-termini (13k). We compared apatite binding affinity between amelogenins and their digest products during proteolysis. We further compared binding affinity among the 3 amelogenins using a Langmuir model for protein adsorption. Amelogenin-apatite binding affinity was progressively reduced with the proteolysis at the C- and N- termini by recombinant pig MMP-20 (rpMMP20) and recombinant human kallikrein-4 (rhKLK4), respectively. The binding affinity of amelogenin to apatite was found to be in the descending order of rP172, rP148, and 13k. Analysis of our data suggests that, before its complete degradation during enamel maturation, stepwise processing of amelogenin by MMP-20 and then KLK4 reduces amelogenin-apatite interaction.

Undergraduate research. Genomics Education Partnership

The Genomics Education Partnership offers an inclusive model for undergraduate research experiences incorporated into the academic year science curriculum, with students pooling their work to contribute to international data bases.

Undergraduate research. Genomics Education Partnership

The Genomics Education Partnership offers an inclusive model for undergraduate research experiences incorporated into the academic year science curriculum, with students pooling their work to contribute to international data bases.

Multivisceral resections of gastrointestinal stromal tumors

20523

Background: Gastrointestinal stromal tumors (GISTs) with positive kit staining, although rare, are the most common mesenchymal neoplasms affecting the gastrointestinal tract. We present our experience in the treatment of disease involving adjacent organs with multivisceral resections. Methods: The clinicopathologic records of twenty-two patients with multivisceral resection, among 170 patients suffered from GISTs treated in our hospital from 1994 to 2005, were retrospectively reviewed. Nine primary tumors originated from the stomach, 4 from the small intestine, 6 from the colorectum, 1 from abdominal cavity, and 2 from the retroperitoneal area. Meanwhile complete follow-up records were available in 15 patients with median 5-year follow-up. Results: The patients included 9 men and 13 women, from 36 to 77 year old. The largest tumor diameter ranged from 2 to 20 cm. The types of multivisceral operation comprised splenectomy (n=8), coloectomy (n=6), nephrectomy (n=5), partial hepatectomy (n=1), duodenectomy (n=1), oophorectomy (n=1), pancreatectomy (n=1), and adrenalectomy (n=1). None of lymph node metastatsis was found in 7 patients with lymph node dissection with gastric GISTs (n=5) or small intestinal GISTs (n=2). The involved organs confirmed by the pathologic diagnosis included kidney (n=2), spleen (n=2), pancreas (n=2), mesentery (n=1), and omentum (n=1). There was no perioperative mortality in this series. Among follow up patients, 9 were alive and 5 were died from the tumor recurrence or metastasis. Among them, one person with gastrectomy, pancreatectomy, adrenalectomy is still alive under 2 year follow-up by imatinib mesylate therapy postoperatively. Conclusions: Complete surgical resection with a negative gross margin by en bloc resection of the involved organs remains the standard treatment for non-metastatic GISTs. Imatinib mesylate represents a major breakthrough in the treatment of advanced GISTs and is the first effective systemic therapy for the disease.

No significant financial relationships to disclose.

The prognostic analysis of gastrointestinal stromal tumor

20534

Objective: To investigate the prognostic factor of gastrointestinal stromal tumor. Methods: The clinicopathological data of 103 patients with gastrointestinal stromal tumors were analyzed restrospectively. Life table, kaplan-meier survival rate and cox regression model were used to evaluate the prognostic factors. Results: The 1 year ,3 years and 5 years total survival rate of these 103 gastrointestinal stromal tumors was 86.3%, 51.7%, 42.8%. Tumor size, mitotic rate, primary organ of tumor and radical surgical excision or not were analyzed respectively, the difference is statistical significance (P<0.05). No significiant difference between the group of sex, age, immunohistochemistry expression and multi-organ resection or not. Conclusion: Flechers’ classification is rational, scientific, simple and feasible. Radical surgical excision is the best therapy to the primary gastrointestinal stomal tumor.

No significant financial relationships to disclose.

NOS2 (iNOS) deficiency in kidney donor accelerates allograft loss in a murine model

Renal NOS2 is expressed and produces abundant nitric oxide (NO) in various renal cells in response to proinflammatory cytokines. However, the role of this enzyme in renal allograft survival remains unknown. Kidney allotransplantation was performed in the murine model of C57BL/6J (H-2(d)) to nephrectomized Balb/c (H-2(b)) mice. Here we show that deficiency in NOS2 expression in kidney donors significantly advanced allograft failure, indicated by decreasing mean survival of recipients receiving NOS2 null grafts (15.4 +/- 6.4 days) as compared to those with wild type grafts (65.4 +/- 28.1 days) (p = 0.0005). Consistent with survival results, NOS2 null grafts had more severe renal tubule injury and decreased renal function compared to wild type grafts. In vitro NOS2 expressing TEC had greater resistance to allogeneic lymphocyte-mediated apoptosis. The addition of exogenous NO inhibited Fas-mediated TEC apoptosis and reduced proliferation of allogeneic lymphocytes. These data suggest that endogenous production of NO through renal NOS2 activity can play a protective role in kidney grafts through attenuating Fas-mediated donor cell apoptosis as well as by inhibiting proliferation of inflammatory infiltrating lymphocytes. Enhanced donor NOS2 expression may be a useful strategy to improve kidney transplant survival.

Increasing resistance of tubular epithelial cells to apoptosis by shRNA therapy ameliorates renal ischemia-reperfusion injury

Renal tubular epithelial cells (TEC) die by apoptosis or necrosis in renal ischemia-reperfusion injury (IRI). Fas/Fas ligand-dependent fratricide is critical in TEC apoptosis, and Fas promotes renal IRI. Therefore, targeting Fas or caspase-8 may have therapeutic potential for renal injury in kidney transplant or failure. RNA silencing by short hairpin RNA (shRNA) is a novel strategy to down-regulate protein expression. Using this approach, silencing of Fas or caspase-8 by shRNA to prevent TEC apoptosis and IRI was evaluated. IRI was induced by renal artery clamping for 45 or 60 min at 32 degrees C in uninephrectomized C57BL/6 mice. Here, we showed that Fas or pro-caspase-8 expression was significantly knocked down in TEC by stable expression of shRNA, resulting in resistance to apoptosis induced by superoxide, IFN-gamma/TNF-alpha and anti-Fas antibody. Inferior vena cava delivery of pHEX-small interfering RNA targeting Fas or pro-caspase-8 resulted in protection of kidney from IRI, indicated by reduction of renal tubular injury (necrosis and apoptosis) and serum creatinine or blood urea nitrogen. Our data suggest that shRNA-based therapy targeting Fas and caspase-8 in renal cells can lead to protection of kidney from IRI. Attenuation of pro-apoptotic proteins using genetic manipulation strategies such as shRNA might represent a novel strategy to promote kidney allograft survival from rejection or failure.

Inhibitors of histone deacetylases promote hematopoietic stem cell self-renewal

BACKGROUND

Histone deacetylases (HDAC) are associated with a variety of transcriptional repressors that control cellular differentiation and proliferation. HDAC inhibitors such as trichostatin A, trapoxin and chlamydocin could be useful tools to modulate these cellular processes. We investigated their effect on the self-renewal of hematopoietic stem cells (HSC) during ex vivo culture.

METHODS

Purified murine HSC with the phenotype c-Kit+,Thy-1.1(lo), Lin(-/lo), Sca-1+ were cultured for 4 days with IL-3, IL-6 and c-Kit ligand without or with HDAC inhibitors, after which their degree of phenotypic differentiation in culture was assessed by flow cytometric analysis. To explore whether HDAC inhibitors could have a beneficial role in human HSC transplantation, mobilized peripheral blood CD34+ cells were cultured with thrombopoietin mimetic peptide, flt3 ligand, and c-Kit ligand, without or with various HDAC inhibitors. The fluorescent dye, carboxyfluorescein-diacetate succinimidylester (CFSE), was used to track division of cell subsets, and engrafting ability was evaluated in a non-obese diabetic (NOD) -SCID xenotransplantation model.

RESULTS

Murine HSC cultured with HDAC inhibitors maintained a more primitive phenotype than control cultures. The number of human HSC expressing Thy-1 increased up to seven-fold during a 5-day culture with HDAC inhibitors compared with control cultures. Chlamydocin was the most effective of the HDAC inhibitors tested at promoting Thy-1 expression on human cells. CFSE tracking showed that the increase in Thy-1+ cells resulted from cell division. In a NOD-SCID repopulation assay, cells exposed to chlamydocin for 24 h displayed an average four-fold higher engrafting ability over control cells.

DISCUSSION

Our studies suggest that HDAC inhibitors can induce ex vivo expansion of human HSC, and may improve engraftment in hematopoietic transplant patients when cell dose is limiting.

Apatite/amelogenin coating on titanium promotes osteogenic gene expression

Osteoblast differentiation and extracellular matrix production are pivotal processes for implant osseointegration or bone tissue engineering. We hypothesized that a biomimetic coating on titanium surfaces, consisting of apatite and amelogenin, would promote such processes. Human Embryonic Palatal Mesenchymal pre-osteoblasts were used as a model for the evaluation of cell adhesion and spreading patterns, as well as mRNA expression of certain osteoblastic gene products. Real-time PCR showed significant (p < 0.05) increase in expression of type I collagen, alkaline phosphatase, and osteocalcin from cells grown on titanium with an apatite/amelogenin composite, as compared with that from cells grown on a pure titanium or apatite coating only. Osteocalcin expression was specifically stimulated by amelogenin added to the culture media. Enhanced attachment and cell spreading were also observed. The biomimetic coating promoting cell adhesion and osteoblast differentiation may have great potential for future dental and biomedical applications.

Mechanical stimulation effects on functional end effectors in osteoblastic MG-63 cells

Receptor activator of Nf-kappaB ligand (RANKL) and osteoprotegerin (OPG) have been implicated in bone metabolism. Specifically, the balance of these factors in conjunction with receptor activator of Nf-kappaB (RANK) is believed to be key in determining the rate of osteoclastogenesis and the net outcome of bone formation/resorption. While it is well accepted that mechanical loading in vivo affects bone formation/resorption and that alterations in the responsiveness of bone cells to mechanical loading have been implicated in metabolic bone diseases, the effect of in vitro mechanical loading on osteoblastic production of OPG and RANKL has not been extensively studied. Thus, in the current study, we developed an in vitro model to load human osteoblasts and studied levels of OPG, RANKL, PGE(2) and macrophage colony stimulating factor (M-CSF). We hypothesized that stimulating osteoblastic cells would increase the release of soluble OPG relative to RANKL favoring a bone-forming (and resorption-inhibiting) event. To accomplish this, we developed a small-scale loading machine that imparts via bending, well-defined substrate deformation to bone cells cultured on artificial substrates. Following 2h of loading and a 1h incubation period, media was collected and levels of soluble OPG, RANKL, PGE(2) and M-CSF were quantified using ELISA and western blotting. We found that mechanical loading significantly increased soluble OPG levels relative to RANKL at this 3h time point. Levels of soluble and cellular RANKL detected were not significantly affected by mechanical stimulation. The relative shift in abundance of OPG over RANKL associated with applied mechanical stimulation suggests the soluble OPG:RANKL ratio may be important in load-induced coupling mechanisms of bone cells.

Renal tubular epithelial cell apoptosis by Fas-FasL–dependent self-injury can augment renal allograft injury

The role of Fas-FasL interactions in kidney allograft injury may be complex as renal tubular epithelial cells (TEC) express both Fas and FasL. The role and regulation of TEC self-injury has not been investigated. In co-cultures of TEC, FasL-bearing, Fas-null TEC was demonstrated to induce apoptosis of TEC-bearing Fas. Co-culturing effector lpr-TEC (M3.1-lpr) with target WT-TEC (CS3.7) at a ratio of 10:1 (E/T) induced 15.2 +/- 2.4% of target apoptosis as compared to its basal level of 2.6 +/- 0.3%. Similarly lpr-TEC induced apoptosis in gld-TEC (MRM-gld) from a basal level of 3.7 +/- 0.2% to 6.4 +/- 0.3%. Expression of kidney Fas-FasL on injury was tested in a renal transplant model. C57BL/6 (B6) mice were transplanted with Fas-deficient C3H-lpr/lpr or FasL mutation C3H-gld/gld kidneys as compared to normal (wild-type [WT]) C3H/Hej donors. Survival of both lpr and gld recipient was improved compared to WT donors (P <.05) as was function of lpr and gld kidneys indicated by a lower serum creatinine (LPR: 41 +/- 8 micromol/L; GLD: 52 +/- 7 micromol/L) as compared to the WT donors (84 +/- 8 micromol/L, P <.001). These results demonstrate that activated TEC may commit a novel and previously unreported form of self-injury (fractricide) through Fas-FasL. These results suggest that inhibition of renal Fas or FasL might be a useful strategy to prevent TEC loss during rejection.