Generation,characterization, and heterologous expression of wild-type and up-regulated forms of Arabidopsis thaliana leaf ADP-glucose pyrophosphorylase

ADP-glucose pyrophosphorylase (AGPase), a key enzyme in starch biosynthesis of higher plants, consists of a pair of regulatory large (LS) and catalytically small (SS) subunits. In plants, these subunits are coded by multiple genes resulting in the formation of tissue-specific enzyme forms, which are differentially regulated during plant growth and development. Some AGPase isoforms differ in catalytic and regulatory properties as well as intracellular location. In an effort to gain a better understanding of the role of the leaf AGPase in carbon partitioning and its effect on plant productivity, the Arabidopsis leaf AGPase containing the mature forms of the SS and LS was expressed in a heterologous expression system and characterized enzymatically. The Arabidopsis recombinant AGPase had kinetic values for 3-phosphoglyceric acid, glucose-1-phosphate and Mg(2+) similar to those of the native enzyme. As the N-terminus of the LS has been suggested to be involved in enzyme function, the length of the N-terminal region was extended or shortened. Of the five modified LSs analyzed, only the T5 form lacking six residues of the mature N-terminus was able to form detectable levels of enzyme activity, indicating that the N-terminal region is critical for enzyme function. Two up-regulatory LS mutations that allosterically activate the potato enzyme, a stem isoform, were introduced into the corresponding Arabidopsis LS sequences and co-expressed with wild-type SS. Both modified enzymes showed up-regulatory properties, indicating that these specific residue changes were also operational in the leaf isoform.     

The Effects of Levosimendan Exposure on Oxidant/Antioxidant Status and Trace Element Levels in the Pulmonary Artery of Rats

We investigated both the effect of levosimendan and the role of oxidant/antioxidant status and trace element levels in the pulmonary artery of rats. Fourteen male Wistar albino rats were randomly divided into two groups of seven animals each. Group 1 was not exposed to levosimendan and served as a control. Levosimendan (12 μg/kg) diluted in 10 ml 0.9 % NaCl was administered intraperitoneally to group 2. Animals of both groups were killed after 3 days, and their pulmonary arteries were harvested to determine changes in tissue oxidant/antioxidant status and trace element levels. The animals in both groups were killed 72 h after the levosimendan exposure treatment, and pulmonary arteries were harvested to determine levels of the lipid peroxidation product MDA and the antioxidant GSH as well as the decreased activity of antioxidant enzymes such as SOD, GSH-Px and CAT. It was found that MDA levels increased in pulmonary artery tissues of rats after levosimendan administration. The GSH level decreased in the pulmonary artery of rats after levosimendan treatment. Co, Mn, Fe, Cd and Pb levels were significantly higher (P < 0.001) and Mg, Zn and Cu levels significantly lower (P < 0.001) in the levosimendan group compared to the control group. These results suggest that levosimendan treatment caused an increase in free radical production and a decrease in antioxidant enzyme activity in the pulmonary artery of levosimendan-treated rats. It also caused a decrease or increase in the levels of many minerals in the pulmonary artery, which is an undesirable condition for normal pharmacological function.     

沙尘胁迫对阿月浑子光合作用及叶绿素荧光特性的影响

为了探讨长期沙尘胁迫下阿月浑子叶片光合性能的变化机制,以室内盆栽阿月浑子为材料,对叶片进行覆盖厚度为2mg/cm2(轻度),9 mg/cm2(重度)的沙尘处理,无沙尘覆盖为对照,并分别在处理后第7天、14天、28天和42天,测定叶片光合CO2同化速率,叶绿素含量以及叶绿素荧光特性等参数。结果表明,阿月浑子叶片的净光合速率(Pn)和气孔导度(Gs)随沙尘处理时间延长而下降,重度沙尘处理下Pn和Gs下降幅度比轻度大,胞间CO2浓度(Ci)处理前期增加而后期下降,重度沙尘处理下Ci增幅比轻度小;叶绿素a(Chl-a)、叶绿素b(Chl-b)和总叶绿素含量均随处理时间的延长而下降,在重度沙尘处理下下降幅度比轻度沙尘处理大,Chl-a的下降速率大于Chl-b,叶绿素a和b的比值(Chl-a/Chl-b)在重度沙尘处理下逐渐下降,而在轻度沙尘处理下呈升-降-升趋势;PSⅡ最大光化学效率(Fv/Fm)不同程度下降,在重度沙尘处理下下降幅度比轻度沙尘处理大;轻度沙尘覆盖下实际光化学效率(ΦPSⅡ)及非环式电子传递效率(ETR)在处理第42天显著下降,而重度覆盖处理先急剧下降,后期逐渐恢复;非光化学荧光猝灭(NPQ)在轻度胁迫下先下降而后逐步上升,在重度处理下则在处理前期就迅速上升。从而得出结论,阿月浑子轻度沙尘胁迫条件下前期其光合作用非气孔限制贡献率大于气孔限制,随胁迫时间气孔限制逐渐占优势,并且随处理时间的延长其吸收的光能用于保护性耗散量逐渐增加,使其光合CO2同化效率下降。     

Natural history of 11 cases of twin-twin transfusion syndrome without intervention.

The natural history of 11 cases of twin-twin transfusion syndrome (TTTS) in monochorionic diamniotic (MCDA) twin pregnancies has been reviewed. Seven cases before 28 weeks and four pregnancies after 28 weeks had been followed up without intervention. Eight cases had premature uterine contractions. All seven pregnancies before 28 weeks aborted, leading to a 100% mortality rate. After 28 weeks all mothers delivered live births. The diagnosis of TTTS before 28 weeks, and with premature uterine contraction, seems to be a poor prognostic sign.     

A phenome-guided drug repositioning through a latent variable model

Background

The phenome represents a distinct set of information in the human population. It has been explored particularly in its relationship with the genome to identify correlations for diseases. The phenome has been also explored for drug repositioning with efforts focusing on the search space for the most similar candidate drugs. For a comprehensive analysis of the phenome, we assumed that all phenotypes (indications and side effects) were inter-connected with a probabilistic distribution and this characteristic may offer an opportunity to identify new therapeutic indications for a given drug. Correspondingly, we employed Latent Dirichlet Allocation (LDA), which introduces latent variables (topics) to govern the phenome distribution.

Results

We developed our model on the phenome information in Side Effect Resource (SIDER). We first developed a LDA model optimized based on its recovery potential through perturbing the drug-phenotype matrix for each of the drug-indication pairs where each drug-indication relationship was switched to “unknown” one at the time and then recovered based on the remaining drug-phenotype pairs. Of the probabilistically significant pairs, 70% was successfully recovered. Next, we applied the model on the whole phenome to narrow down repositioning candidates and suggest alternative indications. We were able to retrieve approved indications of 6 drugs whose indications were not listed in SIDER. For 908 drugs that were present with their indication information, our model suggested alternative treatment options for further investigations. Several of the suggested new uses can be supported with information from the scientific literature.

Conclusions

The results demonstrated that the phenome can be further analyzed by a generative model, which can discover probabilistic associations between drugs and therapeutic uses. In this regard, LDA serves as an enrichment tool to explore new uses of existing drugs by narrowing down the search space.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2105-15-267) contains supplementary material, which is available to authorized users.     

Effective biofilm control in a membrane biofilm reactor using a quenching bacterium (Rhodococcus sp. BH4)

The biofilm thickness in membrane biofilm reactors (MBfRs) is an important factor affecting system performance because excessive biofilm formation on the membrane surface inhibits gas diffusion to the interior of the biofilm, resulting in a significant reduction in the performance of contaminant removal. This study provides innovative insights into the control of biofilm thickness in O₂-based MBfRs by using the quorum quenching (QQ) method. The study was carried out in MBfRs operated at different gas pressures and hydraulic retention times (HRTs) using QQ beads containing Rhodococcus sp. BH4 at different amounts. The highest performance was observed in reactors operated with 0.21 ml QQ bead/cm² membrane surface area, 12 HRTs and 1.40 atm. Over this period, the performance increase in chemical oxygen demand (COD) removal was 25%, while the biofilm thickness on the membrane surface was determined to be 250 μm. Moreover, acetate and equivalent oxygen flux results reached 6080 and 10 640 mg·m⁻²·d⁻¹ maximum values, respectively. The extracellular polymeric substances of the biofilm decreased significantly with the increase of gas pressure and QQ beads amount. Polymerase chain reaction denaturing gradient gel electrophoresis results showed that the microbial community in the MBfR system changed depending on operating conditions and bead amount. The results showed that the QQ method was an effective method to control the biofilm thickness in MBfR and provide insights for future research.     

Recurrence patterns of pancreatic cancer treated with adjuvant intensity modulated radiotherapy

BackgroundThe aim of this study was to investigate the recurrence patterns in pancreatic cancer patients treated with adjuvant intensity modulated radiotherapy (IMRT) and to correlate the sites of locoregional recurrence with radiotherapy target volumes.Materials and methodsThirty-eight patients who had undergone resection and adjuvant chemoradiation for pancreatic cancer were evaluated. Radiotherapy (RT) was started after 1–3 cycles of adjuvant chemotherapy (CHT). Clinical target volume (CTV) was contoured according to the RTOG guideline. All patients were treated with IMRT with a dose of 45–50.4 Gy. Computerized tomography (CT) images at the time of recurrence were correlated with radiotherapy plans. Locoregional recurrences were classified as in-field, out-field and marginal.ResultsMedian overall survival (OS) was 19 months. One- and 2-year OS rates were 73.6% and 37.1%, respectively. Locoregional recurrence and distant metastases were observed in 11 (28.9%) and 23 (60.5%) patients, respectively. For the 11 locoregional recurrences, 7 were in-field, 1 was marginal, and 3 were out-of-field. One patient had isolated local, 2 patients had isolated regional and 15 (57.6%) patients had only distant failures. The first presentations of failures were mostly distant (58%). On multivariate analysis, tumor size ≥ 3 cm (p = 0.011) and positive vascular invasion (p = 0.014) predicted for worse OS rate.ConclusionsThe majority of locoregional recurrences were in the radiation field among pancreatic cancer patients treated with postoperative IMRT. However, failures were predominantly distant, and improvement of systemic control may be of particular interest.     

The number of CD161 positive Th17 cells are decreased in head and neck cancer patients

Background

Despite lots of research efforts, the pathology of head and neck cancer remains elusive. Accumulating evidence suggests that the innate and adaptive immunity plays an important role in HNSCC (Head and Neck Squamous Cell Carcinoma) development. Recently, a new T helper cell subset additional to the classical Th1 and Th2 cells was identified called Th17 cells, due to their secretion of IL-17. However, Th17 cells also produce additional proinflammatory cytokines and many other cytokines are involved in their differentiation and expansion. It was shown that Th17 cells play a prominent role in host defense but are also associated with the development of autoimmune diseases. The role of Th17 cells in cancer pathogenesis remains nebulous.

Methods

Th17 cells of peripheral blood, primary tumors and metastatic lymph nodes were FACS analyzed for their CD161 expression. Supernatants of the permanent HNSCC cell line BHY were used to induce Th17 cells by HNSCC tumor mileu.

Results

Here we show that Th17 cells from patients with HNSCC downregulate the Th17 cell surface receptor CD161 in peripheral blood as well as in primary tumors and especially in metastatic lymph nodes.

Conclusion

We have showed for the first time alterations of Th17 cell phenotype in HNSCC patients.