Interfacial Behaviors and Oil Detachment Mechanisms by Modified Silica Nanoparticles: Insights from Molecular Simulations.

Surfactant flooding has been considered as a promising approach for chemically enhanced oil recovery (EOR). However, this technique encounters several limitations, such as high costs, environmental concerns, and reduced efficiency under high-temperature and high-salinity reservoir conditions. Recently, nanoparticles have also been proposed as an alternative for EOR due to their superior properties compared with surfactants. This research employs molecular dynamics simulations to explore the impact of modified SiO2 nanoparticles on oil-water interfacial behaviors and the detachment of oil droplets from an oil-wet surface. The simulation results reveal that modified nanoparticles, featuring hydrophilic and hydrophobic functional groups, have slight impacts on interfacial tension reduction of the oil-water interface. Nanoparticles with varying degrees of modification exhibit distinct positions within the interface, consequently influencing the thickness of the interfacial layer. Notably, the interactions among the nanoparticles, oil molecules, and surface facilitate the formation of a water channel, thereby enhancing the process of oil detachment. Comparative analysis indicates that in terms of oil displacement efficiency, the thickness of the interfacial layer has a more significant impact than interfacial tension reduction. Furthermore, to elucidate the mechanisms of modified nanoparticles enhancing the oil recovery rate, the interaction energies among the oil droplet, nanoparticles, water, and surface are analyzed. The molecular-level insights derived from this investigation could provide valuable guidance for the design of modified nanoparticles tailored to EOR applications.

Numerical simulation of the effect of hypergravity on the dendritic growth characteristics of aluminum alloys.

The cellular automata-lattice Boltzmann method is used to simulate the dendritic growth process of aluminum alloys under the action of hypergravity by performing coupling heat and mass transfer, solidification and flow. The dendrite arm spacing, growth rate, and dendrite morphology vary greatly with the size and direction of hypergravity, and solute segregation occurs. Compared with the gravity of the earth (1 g), hypergravity strongly strengthens the buoyancy-driven flow and considerably affects the morphology of the solidified grain. The dendritic growth rate is also accelerating. According to the direction of hypergravity in relation to the dendritic growth direction, there exist different flow states that show stable or unstable dendritic growth dynamics. For columnar crystal growth, when the hypergravity and growth direction are identical, the dendrite tip undergoes downward melt flow, and the dendrite grows in a stable manner. When the hypergravity and the growth direction are opposite, the dendrite tip undergoes upward melt flow, the dendrite grows in an unstable manner, and the primary dendrite spacing decreases. For the growth of equiaxed crystals, the convection induced by hypergravity causes the equiaxed crystals to be asymmetric, and the solute segregates in the direction of gravity. Channel segregation occurs in the mushy zone in the presence of equiaxed crystal chains.

Experimental Study on the Chemical Reaction Characteristics in the Calcination Process of an 811 Ternary Cathode Material.

The research on 811 ternary cathode materials is mainly based on synthesis and modification. However, the preparation process of these materials is accompanied by complex chemical reactions, and the reaction process and corresponding kinetic analysis have not been widely explored. Under different oxygen concentrations, this study analyzed the chemical reaction mechanism of the raw material's (namely, Ni0.8Co0. 1Mn0. 1(OH)2 and LiOH·H2O mixture, which is referred to as the raw material hereinafter) calcination process by non-isothermal thermogravimetry, differential scanning calorimetry, and in situ X-ray diffraction. Based on the obtained data, multiple heating rate methods were used to calculate the reaction mechanism functions and kinetic parameters at each stage as well as the corresponding activation energy and pre-exponential factor. Results showed that four chemical reactions occurred successively during the calcination process of the raw materials with each corresponding to a different kinetic function, pre-exponential factor, and activation energy. Comparing the calcination characteristics under different oxygen concentrations showed that the activation energy was the smallest when the oxygen concentration was 60%.

Conjugated Polymer/Graphene composite as conductive Agent-Free electrode materials towards High-Performance lithium ion storage.

Polymer materials containing C6 rings and CO become promising electrode materials for high-performance lithium ion batteries (LIBs). However, the poor electronic conductivity severely restricts its further application. Herein, we design and construct a pyromellitic dianhydride anhydride anthraquinone/reduced graphene oxides (PMAQ/rGO-40) composite as an anode material for LIBs. The PMAQ is uniformly wrapped by conductive rGO nanosheets. The PMAQ/rGO-40 electrode without additional conductive agents displays a discharge capacity of 253 mAh g-1 over 3000 cycles under 2A g-1, which is higher than that of the PMAQ electrode with conductive agents. Meanwhile, a capacity of 196 mAh g-1 is achieved under 5A g-1. The enhanced cycling performance and rate ability are attributed to the rGO conductive network, which promotes electronic transport capability. In addition, the lithium ion storage mechanism and kinetics in the PMAQ/rGO-40 are investigated. The excellent electrochemical performance shows the potential application of the PMAQ/rGO composite anode material for high performance LIBs.

Multiscale modeling of gas flow behaviors in nanoporous shale matrix considering multiple transport mechanisms.

This study proposes a multiscale model combining molecular simulation and the lattice Boltzmann method (LBM) to explore gas flow behaviors with multiple transport mechanisms in nanoporous media of shale matrix. The gas adsorption characteristics in shale nanopores are first investigated by molecular simulations, which are then integrated and upscaled into the LBM model through a local adsorption density parameter. In order to adapt to high Knudsen number and nanoporous shale matrix, a multiple-relaxation-time pore-scale LBM model with a regularization procedure is developed. The combination of bounce-back and full diffusive boundary condition is adopted to take account of gas slippage and surface diffusion induced by gas adsorption. Molecular simulation results at the atomic scale show that gas adsorption behaviors are greatly affected by the pressure and pore size of the shale organic nanopore. At the pore scale, the gas transport behaviors with multiple transport mechanisms in nanoporous shale matrix are explored by the developed multiscale model. Simulation results indicate that pressure exhibits more significant influences on the transport behaviors of shale gas than temperature does. Compared with porosity, the average pore size of nanoporous shale matrix plays a more significant role in determining the apparent permeability of gas transport. The roles of the gas adsorption layer and surface diffusion in shale gas transport are discussed. It is observed that under low pressure, the gas adsorption layer has a positive influence on gas transport in shale matrix due to the strong surface diffusion effect. The nanoporous structure with the anisotropy characteristic parallel to the flow direction can enhance gas transport in shale matrix. The obtained results may provide underlying and comprehensive understanding of gas flow behaviors considering multiple transport mechanisms in shale matrix. Also, the proposed multiscale model can be considered as a powerful tool to invesigate the multiscale and multiphysical flow behaviors in porous media.

[Abundance and Fluorescent Components of Dissolved Organic Matter Affected by Land Use in a Drinking Water Source].

Regional concentrations, fluorescent components, and sources of dissolved organic matter (DOM) in a drinking water source in Chaobai River across seasons were investigated here using fluorescence excitation-emission matrices, parallel factor analysis, and fluorescence indexes. Five fluorescent-DOM components were identified, including two microbial humic-like components and one autochthonous tyrosine-like, one reduced quinone-like, and one terrestrial humic-like component. DOM was mainly derived from microorganisms. The farmland-dominated region showed the highest DOM concentration and significantly lower maximum fluorescence intensities (Fmax) of almost all fluorescent components than those in the forest-dominated region. The region dominated by urban lands exhibited obviously lower DOM concentrations than those in the farmland-dominated region and lower Fmax values of fluorescent components than those in the forest-dominated region. No interaction was found between land use and season when considering their effects on DOM. Season had a significant influence on the humification degree of DOM. This study shows that agricultural land use had a greater impact on DOM than that of forests and urban areas, and the increased riverine DOM resulting from farmland was mainly non-fluorescent parts.

Peptide Effectors in Phytonematode Parasitism and Beyond.

Peptide signaling is an emerging paradigm in molecular plant-microbe interactions with vast implications for our understanding of plant-nematode interactions and beyond. Plant-like peptide hormones, first discovered in cyst nematodes, are now recognized as an important class of peptide effectors mediating several different types of pathogenic and symbiotic interactions. Here, we summarize what has been learned about nematode-secreted CLAVATA3/EMBRYO SURROUNDING REGION-RELATED (CLE) peptide effectors since the last comprehensive review on this topic a decade ago. We also highlight new discoveries of a diverse array of peptide effectors that go beyond the CLE peptide effector family in not only phytonematodes but in organisms beyond the phylum Nematoda.

Phytonematode peptide effectors exploit a host post-translational trafficking mechanism to the ER using a novel translocation signal.

Cyst nematodes induce a multicellular feeding site within roots called a syncytium. It remains unknown how root cells are primed for incorporation into the developing syncytium. Furthermore, it is unclear how CLAVATA3/EMBRYO SURROUNDING REGION (CLE) peptide effectors secreted into the cytoplasm of the initial feeding cell could have an effect on plant cells so distant from where the nematode is feeding as the syncytium expands. Here we describe a novel translocation signal within nematode CLE effectors that is recognized by plant cell secretory machinery to redirect these peptides from the cytoplasm to the apoplast of plant cells. We show that the translocation signal is functionally conserved across CLE effectors identified in nematode species spanning three genera and multiple plant species, operative across plant cell types, and can traffic other unrelated small peptides from the cytoplasm to the apoplast of host cells via a previously unknown post-translational mechanism of endoplasmic reticulum (ER) translocation. Our results uncover a mechanism of effector trafficking that is unprecedented in any plant pathogen to date, andthey illustrate how phytonematodes can deliver effector proteins into host cells and then hijack plant cellular processes for their export back out of the cell to function as external signaling molecules to distant cells.

Computational Insights into LixOy Formation, Nucleation, and Adsorption on Carbon Nanotube Electrodes in Nonaqueous Li-O2 Batteries.

Recent theoretical and experimental studies have shown that the formation of Li2O2, the main discharge product of nonaqueous Li-O2 batteries, is a complex multistep reaction process. The formation, nucleation, and adsorption of LixOy (x and y = 0, 1, and 2) and (Li2O2)n clusters with n = 1-4 on the surface of carbon nanotubes (CNTs) were investigated by periodic density functional theory calculation. The results showed that both Li2O2 and Li2O on CNT electrodes are preferentially generated by lithiation reaction rather than disproportionation reaction. The free energy profiles demonstrate that the discharge potentials of 2.54 and 1.29 V are the threshold values of spontaneous nucleation of (Li2O2)2 and (Li2O)2 on a CNT surface, respectively. The electronic structure indicates that Li2O2 is a p-type semiconductor, while Li2O exhibits the properties of an insulator. Interestingly, once Li2O2 molecules condense into large clusters, they will be repelled away from the CNT surface and continue to grow into large-sized Li2O2. Our results provide insights into the full understanding of the electrochemical reaction mechanism and product formation processes of lithium oxides in the cathodes of Li-O2 batteries.

Molecular simulation of CO2/CH4/H2O competitive adsorption and diffusion in brown coal.

Carbon dioxide enhanced coalbed methane recovery (CO2-ECBM) has been proposed as a promising technology for the natural gas recovery enhancement as well as mitigation of CO2 emissions into the atmosphere. Adsorption and diffusion of CO2/CH4 mixture play key roles in predicting the performance of CO2-ECBM project, i.e., the production of coalbed methane as well as the geological sequestration potential of carbon dioxide. In the present work, the mechanism of competitive adsorption and diffusion of CO2/CH4/H2O mixture in brown coal were investigated by employing grand canonical Monte Carlo and molecular dynamics simulation. The effects of temperature and pressure on competitive adsorption and diffusion behaviours were explored. It is found that CO2 has much stronger adsorption ability on brown coal than CH4. The adsorption amounts of CO2/CH4 increase with pressure but have a decreasing trend with temperature. High adsorption selectivity of CO2/CH4 is observed with pressure lower than 0.1 MPa. In addition, the effects of moisture content in brown coal on the adsorption characteristics have been examined. Simulation results show that the adsorption capacities of CO2/CH4 are significantly suppressed in moist brown coal. The competitive adsorption of CO2/CH4/H2O follows the trend of H2O ≫ CO2 > CH4. Moreover, the results reveal that moisture content has great effects on the self-coefficients of CO2/CH4. Compared with dry coal, the self-diffusion coefficients of CO2 and CH4 reduce by 78.7% and 75.4% in brown coal with moisture content of 7.59 wt%, respectively. The microscopic insights provided in this study will be helpful to understand the competitive adsorption and diffusion mechanism of CO2/CH4/H2O in brown coal and offer some fundamental data for CO2-ECBM project.

Cellular distribution of secretory pathway markers in the haploid synergid cells of Arabidopsis thaliana.

In flowering plants, cell-cell communication plays a key role in reproductive success, as both pollination and fertilization require pathways that regulate interactions between many different cell types. Some of the most critical of these interactions are those between the pollen tube (PT) and the embryo sac, which ensure the delivery of sperm cells required for double fertilization. Synergid cells function to attract the PT through secretion of small peptides and in PT reception via membrane-bound proteins associated with the endomembrane system and the cell surface. While many synergid-expressed components regulating PT attraction and reception have been identified, few tools exist to study the localization of membrane-bound proteins and the components of the endomembrane system in this cell type. In this study, we describe the localization and distribution of seven fluorescent markers that labelled components of the secretory pathway in synergid cells of Arabidopsis thaliana. These markers were used in co-localization experiments to investigate the subcellular distribution of the two PT reception components LORELEI, a GPI-anchored surface protein, and NORTIA, a MILDEW RESISTANCE LOCUS O protein, both found within the endomembrane system of the synergid cell. These secretory markers are useful tools for both reproductive and cell biologists, enabling the analysis of membrane-associated trafficking within a haploid cell actively involved in polar transport.

Molecular insights into competitive adsorption of CO2/CH4 mixture in shale nanopores.

In the present study, competitive adsorption behaviour of supercritical carbon dioxide and methane binary mixture in shale organic nanopores was investigated by using grand canonical Monte Carlo (GCMC) simulations. The model was firstly validated by comparing with experimental data and a satisfactory agreement was obtained. Then the effects of temperature (298-388 K), pressure (up to 60 MPa), pore size (1-4 nm) and moisture content (0-2.4 wt%) on competitive adsorption behaviour of the binary mixture were examined and discussed in depth. It is found that the adsorption capacity of carbon dioxide in shale organic nanopores is much higher than that of methane under various conditions. The mechanism of competitive adsorption was discussed in detail. In addition, the results show that a lower temperature is favorable to both the adsorption amount and selectivity of CO2/CH4 binary mixture in shale organic nanopores. However, an appropriate CO2 injection pressure should be considered to take into account the CO2 sequestration amount and the exploitation efficiency of shale gas. As for moisture content, different influences on CO2/CH4 adsorption selectivity have been observed at low and high moisture conditions. Therefore, different simulation technologies for shale gas production and CO2 sequestration should be applied depending on the actual moisture conditions of the shale reservoirs. It is expected that the findings in this work could be helpful to estimate and enhance shale gas resource recovery and also evaluate CO2 sequestration efficiency in shale reservoirs.

Arabidopsis LORELEI, a Maternally Expressed Imprinted Gene, Promotes Early Seed Development.

In flowering plants, the female gametophyte controls pollen tube reception immediately before fertilization and regulates seed development immediately after fertilization, although the controlling mechanisms remain poorly understood. Previously, we showed that LORELEI (LRE), which encodes a putative glycosylphosphatidylinositol-anchored membrane protein, is critical for pollen tube reception by the female gametophyte before fertilization and the initiation of seed development after fertilization. Here, we show that LRE is expressed in the synergid, egg, and central cells of the female gametophyte and in the zygote and proliferating endosperm of the Arabidopsis (Arabidopsis thaliana) seed. Interestingly, LRE expression in the developing seeds was primarily from the matrigenic LRE allele, indicating that LRE expression is imprinted. However, LRE was biallelically expressed in 8-d-old seedlings, indicating that the patrigenic allele does not remain silenced throughout the sporophytic generation. Regulation of imprinted LRE expression is likely novel, as LRE was not expressed in pollen or pollen tubes of mutants defective for MET1, DDM1, RNA-dependent DNA methylation, or MSI-dependent histone methylation. Additionally, the patrigenic LRE allele inherited from these mutants was not expressed in seeds. Surprisingly, and contrary to the predictions of the parental conflict hypothesis, LRE promotes growth in seeds, as loss of the matrigenic but not the patrigenic LRE allele caused delayed initiation of seed development. Our results showed that LRE is a rare imprinted gene that functions immediately after double fertilization and supported the model that a passage through the female gametophyte establishes monoalleleic expression of LRE in seeds and controls early seed development.

The Role of LORELEI in Pollen Tube Reception at the Interface of the Synergid Cell and Pollen Tube Requires the Modified Eight-Cysteine Motif and the Receptor-Like Kinase FERONIA.

In angiosperms, pollen tube reception by the female gametophyte is required for sperm release and double fertilization. In Arabidopsis thaliana lorelei (lre) mutants, pollen tube reception fails in most female gametophytes, which thus remain unfertilized. LRE encodes a putative glycosylphosphatidylinositol (GPI)-anchored surface protein with a modified eight-cysteine motif (M8CM). LRE fused to citrine yellow fluorescent protein (LRE-cYFP) remains functional and localizes to the synergid plasma membrane-rich filiform apparatus, the first point of contact between the pollen tube and the female gametophyte. Structure-function analysis using LRE-cYFP showed that the role of LRE in pollen tube reception requires the M8CM, but not the domains required for GPI anchor addition. Consistently, LRE-cYFP-TM, where GPI anchor addition domains were replaced with a single-pass transmembrane domain, fully complemented the pollen tube reception defect in lre-7 female gametophytes. Ectopically expressed and delivered LRE-cYFP from pollen tubes could non-cell-autonomously complement the pollen tube reception defect in lre female gametophytes, only if they expressed FERONIA. Additionally, pollen tube-expressing LRE variants lacking domains critical for GPI anchor addition also rescued lre female gametophyte function. Therefore, LRE and FERONIA jointly function in pollen tube reception at the interface of the synergid cell and pollen tube.

Downregulation of chloroplast RPS1 negatively modulates nuclear heat-responsive expression of HsfA2 and its target genes in Arabidopsis.

Heat stress commonly leads to inhibition of photosynthesis in higher plants. The transcriptional induction of heat stress-responsive genes represents the first line of inducible defense against imbalances in cellular homeostasis. Although heat stress transcription factor HsfA2 and its downstream target genes are well studied, the regulatory mechanisms by which HsfA2 is activated in response to heat stress remain elusive. Here, we show that chloroplast ribosomal protein S1 (RPS1) is a heat-responsive protein and functions in protein biosynthesis in chloroplast. Knockdown of RPS1 expression in the rps1 mutant nearly eliminates the heat stress-activated expression of HsfA2 and its target genes, leading to a considerable loss of heat tolerance. We further confirm the relationship existed between the downregulation of RPS1 expression and the loss of heat tolerance by generating RNA interference-transgenic lines of RPS1. Consistent with the notion that the inhibited activation of HsfA2 in response to heat stress in the rps1 mutant causes heat-susceptibility, we further demonstrate that overexpression of HsfA2 with a viral promoter leads to constitutive expressions of its target genes in the rps1 mutant, which is sufficient to reestablish lost heat tolerance and recovers heat-susceptible thylakoid stability to wild-type levels. Our findings reveal a heat-responsive retrograde pathway in which chloroplast translation capacity is a critical factor in heat-responsive activation of HsfA2 and its target genes required for cellular homeostasis under heat stress. Thus, RPS1 is an essential yet previously unknown determinant involved in retrograde activation of heat stress responses in higher plants.

Carbonylation and loss-of-function analyses of SBPase reveal its metabolic interface role in oxidative stress, carbon assimilation, and multiple aspects of growth and development in Arabidopsis.

Sedoheptulose-1,7-bisphosphatase (SBPase) is a Calvin cycle enzyme and functions in photosynthetic carbon fixation. We found that SBPase was rapidly carbonylated in response to methyl viologen (MV) treatments in detached leaves of Arabidopsis plants. In vitro activity analysis of the purified recombinant SBPase showed that SBPase was carbonylated by hydroxyl radicals, which led to enzyme inactivation in an H(2)O(2) dose-dependent manner. To determine the conformity with carbonylation-caused loss in enzymatic activity in response to stresses, we isolated a loss-of-function mutant sbp, which is deficient in SBPase-dependent carbon assimilation and starch biosynthesis. sbp mutant exhibited a severe growth retardation phenotype, especially for the developmental defects in leaves and flowers where SBPASE is highly expressed. The mutation of SBPASE caused growth retardation mainly through inhibition of cell division and expansion, which can be partially rescued by exogenous application of sucrose. Our findings demonstrate that ROS-induced oxidative damage to SBPase affects growth, development, and chloroplast biogenesis in Arabidopsis through inhibiting carbon assimilation efficiency. The data presented here provide a case study that such inactivation of SBPase caused by carbonyl modification may be a kind of adaptation for plants to restrict the operation of the reductive pentose phosphate pathway under stress conditions.

[Diagnosis and surgical treatment for non-functional islet cell tumor: a retrospective analysis of 44 cases].

OBJECTIVE: To evaluate the methods of diagnosis and surgical treatment for nonfunctional islet cell tumor (NICT). METHODS: Forty-four patients with non-functional islet cell tumor treated at the First Affiliated Hospital of Nanjing Medical University during January 1968 to June 2008 were analyzed retrospectively. There were 9 males and 35 females, aged from 7- to 70-years-old. Clinical manifestation: 15 cases (34.1%) of abdominal masses, 17 patients (38.6%) with epigastric or back pain, 5 cases of jaundice, 5 cases (11.4%) for upper abdominal fullness or vomiting, 10 cases (22.7%) of pancreatic tumor noticed by routine health checkups or imaging examinations. Imaging examination: CT scan, sonography, ERCP, MRI, upper GI series were performed in 33 (75.0%), 16 (36.4%), 6 (13.6%), 2 (4.5%), and 10 cases (22.7%) respectively. Operation methods: 39 patients (88.6%) underwent surgical resection and the other 5 patients did not. COMPLICATIONS: pancreatic fistula in 7 patients (15.9%), intra-abdominal bleeding in 4 (9.1%), gastrojejunal anastomosis outlet obstruction in 1 (2.3%), biliary fistula in 2 (4.5%) and incisional infection in 3 (6.8%). Surgery related mortality happened in 2 patients (4.5%), both treated before 1999. Twenty-five patients underwent operation between January 1999 and June 2008 were followed up for 6 to 108 months. All survive except one died 75 months after the surgery for unknown reason. CONCLUSIONS: No specific clinical manifestation is recognized for non-functional islet cell tumor. Spiral CT is an optimal diagnostic method, while surgery is the first choice for treatment. Middle segmental pancreatectomy has become an alternative surgical protocol for NICT.

[Expression of the radio-inducible TK suicide gene controlled by Egr-1 promoter in pancreatic cancer cells: an in vitro experiment].

OBJECTIVE: To investigate the expression of radio-inducible herpes simplex virus thymidine kinase (TK) suicide gene controlled by early growth response-1 (Egr-1) promoter in pancreatic cancer cells. METHODS: Adenoviral vector pAdEgr-1-TK containing green fluorescent protein (GFP) was constructed. Human pancreatic cancer cells of the line PC-3 were cultured, transfected with pAdEgr-1-TK, and then exposed to 60Co source gamma-radiation at the doses of 0, 5, 7.5, 10, 15, and 20 Gy respectively for 24 hours. RT-PCR and Western blotting were used to detect the TK mRNA and protein expression in the PC3 cells. RESULTS: The TK mRNA expression levels of the PC3 cells exposed to y-radiation at the doses of 0, 5, 7.5, 10, 15, and 20 Gy respectively were (67.3 +/- 2.1)%, (89.3 +/- 1.0)%, (114.7 +/- 5.7)%, (140.5 +/- 3.1)%, (134.5 +/- 4.0)%, and (117.4 +/- 3.4)% respectively. The TK mRNA expression level was markedly increased after exposure to gamma-radiation, especially that t the dose of 10 Gy (all P < 0.01). The TK protein expression levels of the PC3 cells exposed to y-radiation at the doses of 0, 5, 7.5, 10, 15, and 20 Gy were (5.4 +/- 0.7)%, (7.6 +/- 0.9)%, (21.5 +/- 1.5)%, (35.7 +/- l1.4)%, (32.1 +/- 1.2)%, and (28.8 +/- 1.5)% respectively. CONCLUSION: The Egr-1 promoter causes high expression of TK suicide gene in cancer cells after exposure to 60Co-gamma-radiation. These data provide an experimental basis for gene therapy.

hTERT-targeted E. coli purine nucleoside phosphorylase gene/6-methylpurine deoxyribose therapy for pancreatic cancer.

BACKGROUND: Pancreatic cancer is one of the most common tumors and has a 5-year survival for all stages of less than 5%. Most patients with pancreatic cancer are diagnosed at an advanced stage and therefore are not candidates for surgical resection. In recent years, investigation into alternative treatment strategies for this aggressive disease has led to advances in the field of gene therapy for pancreatic cancer. E. coli purine nucleoside phosphorylase/6-methylpurine deoxyribose (ePNP/MePdR) is a suicide gene/prodrug system where PNP enzyme cleaves nontoxic MePdR into cytotoxic membrane-permeable compounds 6-methylpurine (MeP) with high bystander activity. hTERT is expressed in cell lines and tissues for telomerase activity. In this study we examined the efficacy of ePNP under the control of hTERT promoter sequences and assessed the selective killing effects of the ePNP/prodrug MePdR system on pancreatic tumors. METHODS: Recombinant pET-PNP was established. The protein of E. coli PNPase was expressed and an antibody to E. coli PNPase was prepared. Transcriptional activities of hTERT promoter sequences were analyzed using a luciferase reporter gene. A recombinant phTERT-ePNP vector was constructed. The ePNP/MePdR system affects SW1990 human pancreatic cancer cell lines in vitro. RESULTS: The hTERT promoter had high transcriptional activity and conferred specificity on cancer cell lines. The antibody to E. coli PNPase was demonstrated to be specific for the ePNP protein. The MePdR treatment induced a high in vitro cytotoxicity on the sole hTERT-ePNP-producing cell lines and affected SW1990 cells in a dose-dependent manner. CONCLUSIONS: The hTERT promoter control of the ePNP/MePdR system can provide a beneficial anti-tumor treatment in pancreatic cancer cell lines including a good bystander killing effect.

Changes of inducible protein-10 and regulated upon activation, normal T cell expressed and secreted protein in acute rejection of pancreas transplantation in rats.

AIM: To investigate the role of IFN-gamma inducible protein -10 (IP-10) and regulated upon activation, normal T cell expressed and secreted (RANTES) protein in acute pancreatic allograft rejection in rats. METHODS: An experimental pancreas transplantation model was established using diabetic SD rats as the recipient, induced by applying streptozocin (STZ). Pancreas transplantation was performed with a physiologic method of portal venous and enteric drainage. Rats were divided into two groups, isograft group (group A, n = 24) and allograft group (group B, n = 24) in which either healthy SD rats or Wistar rats served as donors, respectively. Twelve diabetic or healthy SD rats were used as controls. At d 1, 4, 7, and 10 post transplantation, serum IP-10 and RANTES were assessed by ELISA and their expression in the allografts was determined by immunohistochemistry. RESULTS: In group B (allograft group), the development of acute rejection was significantly correlated with increased serum concentration and tissue expression of IP-10 and RANTES, with a peak level at d 7 post transplantation. In contrast, there was no obvious change before and after transplantation in group A (isograft group). CONCLUSION: Our study suggests a possible role of IP-10 and RANTES in acute rejection and early monitoring of chemokines may be helpful in predicting the outcome of pancreas transplantation.