Treatment of lung cancer via telomerase inhibition: self-assembled nanoplexes versus polymeric nanoparticles as vectors for 2'-O-Methyl-RNA

Antisense oligonucleotide, 2'-O-Methyl-RNA (OMR), is known as potent telomerase inhibitor for the treatment of lung cancer but limited by poor intracellular uptake. Chitosan-coated polymeric nanoparticles were compared to chitosan solution as non-viral vectors for OMR. The study investigated the role of chitosan properties and concentration in improving the efficiency of the nanocarriers in terms of loading, viability, cellular uptake, and telomerase inhibition in human lung cancer cell lines. Certain concentration of chitosan on nanoparticle surface is necessary to significantly increase the cellular uptake. However, excessive chitosan negatively affected the transfection efficiency. Self-assembled nanoplexes with chitosan polymer are preferentially adsorbed to the cell membrane rather than being internalized. Thus, polymeric nanoparticles proved to be superior to cationic polymers as carrier for antisense oligonucleotides. Charge cannot be considered the principle factor behind improved transfection. Uptake studies carried out on air-interface cell cultures to mimic in vivo conditions supported the results on normal cultures showing enhanced uptake of nanoplexes over naked oligonucleotides. OMR nanoplexes reduced telomerase activity by ∼50% in A549 cells concluding the potential of the system as a safe, non-invasive, and efficient treatment for lung carcinoma. These data are prerequisites for the ongoing studies on lung perfusion model and in vivo experiments.

Interindividual reaction time variability is related to resting-state network topology: an electroencephalogram study

Both anatomical and functional brain network studies have drawn great attention recently. Previous studies have suggested the significant impacts of brain network topology on cognitive function. However, the relationship between non-task-related resting-state functional brain network topology and overall efficiency of sensorimotor processing has not been well identified. In the present study, we investigated the relationship between non-task-related resting-state functional brain network topology and reaction time (RT) in a Go/Nogo task using an electroencephalogram (EEG). After estimating the functional connectivity between each pair of electrodes, graph analysis was applied to characterize the network topology. Two fundamental measures, clustering coefficient (functional segregation) and characteristic path length (functional integration), as well as "small-world-ness" (the ratio between the clustering coefficient and characteristic path length) were calculated in five frequency bands. Then, the correlations between the network measures and RT were evaluated in each band separately. The present results showed that increased overall functional connectivity in alpha and gamma frequency bands was correlated with a longer RT. Furthermore, shorter RT was correlated with a shorter characteristic path length in the gamma band. This result suggested that human RTs were likely to be related to the efficiency of the brain integrating information across distributed brain regions. The results also showed that a longer RT was related to an increased gamma clustering coefficient and decreased small-world-ness. These results provided further evidence of the association between the resting-state functional brain network and cognitive function.

Exploring serological classification tree model of active pulmonary tuberculosis by magnetic beads pretreatment and MALDI-TOF MS analysis

Pulmonary tuberculosis (TB) is an infectious disease disturbing status of public health, and accurate diagnosis of TB would effectively help control the disturbance. Our study tried to establish a classification tree model that distinguished active TB from non-TB individuals. We used matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) combined with weak cationic exchange (WCX) magnetic beads to analyse 178 serum samples containing 75 patients with active TB and 103 non-TB individuals (43 patients with common pulmonary diseases and 60 healthy controls). Samples were randomly divided into a training set and a test set. Statistical softwares were applied to construct this model. An amount of 48 differential expressed peaks (P < 0.05) were identified by the training set, and our model was set up by three of them, m/z 7626, 8561 and 8608. This model can discriminate patients with active TB from patients with non-TB with a sensitivity of 98.3% and a specificity of 84.4%. The test set was used to verify the performance, which demonstrated good sensitivity and specificity: 85.7% and 83.3%, respectively. Differential expressed peaks between smear-positive and smear-negative active TB also have been analysed. It came out that m/z 8561 and 8608 not only acted as vital factors in the pathogenesis of active TB but also played an important role in regulating different active TB status. In conclusion, MALDI-TOF MS combined with WCX magnetic beads was a powerful technology for constructing classification tree model, and the model we built could serve as a potential diagnostic tool for active TB.

AKT1 polymorphisms are associated with tuberculosis in the Chinese population

AKT1, a serine/threonine kinase, plays a critical role in the controlling of intracellular growth of Mycobacterium tuberculosis. In this study, we investigated whether polymorphisms in AKT1 affect susceptibility to tuberculosis (TB). Two single nucleotide polymorphisms of AKT1, IVS3+18C>T and +726G>A were genotyped in Chinese patients with pulmonary TB by polymerase chain reaction-restriction fragment length polymorphism. Patients with pulmonary TB had significantly lower IVS3+18 C/C genotype and higher C/T genotype compared with age-, gender- and ethnically matched controls (P < 0.05). The T-A haplotype frequency was significantly higher in patients than in controls (P < 0.05). In conclusion, our result indicates that AKT1 polymorphisms are associated with susceptibility to pulmonary TB.

Experimental and Numerical Study of Improving Heavy Oil Recovery by Alkaline Flooding in Sandpacks

Abstract

Chemical flooding has great potential for enhancing heavy oil recovery, especially for reservoirs where thermal methods are not feasible. It has been shown that the formation of emulsions during chemical flooding can effectively improve sweep efficiency and, consequently, increase heavy oil recovery. The mechanism of flow of oil-in-water (O/W) emulsion in porous media has been extensively studied and simulated using the filtration theory. Few studies have been done for the modelling of water-in-oil (W/O) emulsion flow in heavy oil reservoirs. This study experimentally investigated the effective viscosity of W/O emulsion in porous media. Alkaline flooding tests were performed in channelled sandpacks to demonstrate the effectiveness of sweep efficiency improvement by the in-situ produced W/O emulsions. High tertiary oil recoveries were obtained for all these tests. The alkaline flooding process was simulated by including the observed flow behaviour of extra resistance to water phase flow caused by the formation of W/O emulsions, as well as the adsorption of chemicals, interfacial tension reduction, and in-situ generation of W/O emulsions. These laboratory results and the developed simulation technique are proposed as an improvement to the simulation and design of the field-scale projects of chemical flooding for heavy oil recovery.

Introduction

Many heavy oil reservoirs in Western Canada are not suitable for steam injection techniques due to thin pay thickness. Both field and laboratory results demonstrate that waterflooding of heavy oil reservoirs can only achieve a very low oil recovery. The main causes for the poor sweep efficiency of waterflooding for these heavy oil reservoirs are very adverse mobility ratio, natural area and vertical reservoir heterogeneity and heterogeneity induced by primary production(1,2). Therefore, improving mobility ratio and blocking water flow through channels are essential for improving heavy oil recovery. The in-situ formation of emulsions during alkaline flooding has been recognized as one of the efficient methods to improve sweep efficiency for heavy oil recovery(3,4,5).

The effectiveness of alkaline flooding for acidic crudes was recognized as early as in the 1920s(6). Jennings et al.(3) proposed the mechanism of emulsification and entrapment for alkaline flooding. They carried out caustic flooding tests using a heavy oil. Their results showed that the in-situ produced O/W emulsions tended to plug water fingering and channels, resulting in improved sweep efficiency. Johnson(7) summarized possible mechanisms of alkaline flooding to improve oil recovery: dispersion and entrainment, wettability reversal, and emulsification and entrapment. The formation of W/O emulsions was also observed as a mechanism of improving oil recovery(8,9).

The Presence of Hepatitis B Surface Antigen in the Ova of Pregnant Women and Its Relationship with Intra-Uterine Infection by Hepatitis B Virus

Vertical transmission of hepatitis B virus (HBV) has been proposed to play an important role in mother-to-child transmission, although the extent to which vertical transmission via oocytes contributes to neonatal HBV infection remains unknown. Ovarian biopsies were collected during caesarean sections in 68 clinically asymptomatic pregnant women who were carriers of HBV. The presence of hepatitis B surface antigen (HBsAg) in the ova of pregnant women was determined by immunohistochemistry. Serum markers of HBV infection in pregnant women and their neonates were analysed. It was found that, of 68 women, the ova were positive for HBsAg in only one woman and her neonate was negative for any serum HBV markers 3 days after birth. Of 68 neonates, one was positive for serum HBV markers 3 days after birth and his mother's ova were negative for HBsAg. These findings indicate that vertical transmission via oocytes may not be the major route of HBV intra-uterine infection.

Brushing effects on the growth and mechanical properties of Corispermum mongolicum vary with water regime

High water availability and mechanical stress can induce opposite responses in plants. In arid areas of Northern China the occurrence of high wind and high water availability tend to be negatively correlated. Since turgor pressure is a determinant of the mechanical stability of annuals, it is hypothesised that the effects of mechanical perturbation (MP) on annuals may depend on soil water availability. To test this proposal, we conducted an experiment in which a pioneering annual Corispermum mongolicum was subjected to two levels of MP and water supply, and then determined its growth and mechanical traits. Brushing had no effect on plant height and total biomass, but stimulated leaf and branch production. Water supply affected plant height, basal diameter, total biomass and stem rigidity, but not leaf and branch number, root/shoot ratio or flexibility. With high water availability, brushing stimulated the production of stiffer stems (thicker and with a higher Young's modulus) and more roots relative to shoot mass, but with low water availability MP induced the opposite response. This shows that both the degree and direction of plant responses to MP depend on the presence of other factors. We discuss how the interactive effects of MP and water availability on growth and mechanical properties may help C. mongolicum to establish in windy and arid environments.

Phase I study of chidamide (CS055/HBI-8000), a novel histone deacetylase inhibitor, in patients with advanced solid tumors and lymphomas

3529

Background: Chidamide (CS055/HBI-8000) is a new benzamide type of histone deacetylase (HDAC) inhibitor with low nanomolar activity against HDAC1, 2, 3 and 10. This Phase I study evaluated the safety and tolerability of chidamide in patients (pts) with advanced solid tumors and lymphomas. Methods: 31 pts with refractory or relapsed advanced solid tumors (22) and lymphomas (9) were enrolled in this study. Escalating doses of 5, 10, 17.5, 25, 32.5 and 50 mg Chidamide (each with 3 to 7 pts) were administered orally either twice or three times per week for 4 consecutive weeks every 6 weeks. Results: No dose limiting toxicities (DLTs) were identified in the 2 x per week cohorts (22 pts) up to 50 mg; G2 and G3 hematological toxicities (leukopenia/neutropenia and thrombocytopenia) were observed at 50 mg. DLTs were reported as G3 diarrhea or vomiting in 2 pts in the 3 x per week cohort at 50 mg. Common adverse events were G1/G2, fatigue (n = 11), thrombocytopenia (n = 9), anorexia (n = 8), nausea/vomiting (n = 7), leukopenia/neutropenia (n = 6), hypochromia (n = 6), and diarrhea (n = 5). No cystitis, pericarditis, pericardial effusion or prolonged QTc intervals were observed. Single dose PK analysis in pts with 25, 32.5 and 50 mg revealed T1/2 of 16.8–18.3 h, Tmax of 1–2 h in most cases, and a dose-related increase in Cmax and AUC. Multiple dose PK analysis in pts with 32.5 mg 3 x per week suggested drug accumulation with this regimen. Significant induction of histone (H3) acetylation was observed in peripheral white blood cells, which lasted for 2–3 days in most pts after single dosing. 25 pts with total treatment cycles of 49 (range 1–6) were evaluable for efficacy. 4 pts with T-cell lymphomas (4/5 evaluable) and 1 pt with submandibular adenoid cystic carcinoma achieved PR, and 11 pts (2 B-cell lymphomas and 9 solid tumors) experienced SD. Conclusions: Chidamide was well-tolerated in pts with advanced solid tumors and lymphomas in the tested regimens. In addition, the compound exhibited a relatively long half-life, a long-lasting biomarker response and encouraging antitumor activity at well-tolerated doses. The overall phase I results recommend the 2 x per week regimen for phase II studies.

[Table: see text]

Clonal integration supports the expansion from terrestrial to aquatic environments of the amphibious stoloniferous herb Alternanthera philoxeroides

Effects of clonal integration on land plants have been extensively studied, but little is known about the role in amphibious plants that expand from terrestrial to aquatic conditions. We simulated expansion from terrestrial to aquatic habitats in the amphibious stoloniferous alien invasive alligator weed (Alternanthera philoxeroides) by growing basal ramets of clonal fragments in soils connected (allowing integration) or disconnected (preventing integration) to the apical ramets of the same fragments submerged in water to a depth of 0, 5, 10 or 15 cm. Clonal integration significantly increased growth and clonal reproduction of the apical ramets, but decreased both of these characteristics in basal ramets. Consequently, integration did not affect the performance of whole clonal fragments. We propose that alligator weed possesses a double-edged mechanism during population expansion: apical ramets in aquatic habitats can increase growth through connected basal parts in terrestrial habitats; however, once stolon connections with apical ramets are lost by external disturbance, the basal ramets in terrestrial habitats increase stolon and ramet production for rapid spreading. This may contribute greatly to the invasiveness of alligator weed and also make it very adaptable to habitats with heavy disturbance and/or highly heterogeneous resource supply.

Advanced malignant pleural or peritoneal effusion in patients treated with recombinant adenovirus p53 injection plus cisplatin

The aim of this study was to evaluate the efficacy of recombinant adenovirus p53 agent (rAd-p53) injection combined with cisplatin (CDDP) for the treatment of malignant pleural or peritoneal effusion. After puncture drainage, patients in the treatment group (n = 27) received intracavitary administration of rAd-p53 (2 x 10(12) virus particles) once a week for 4 weeks. At 48 h after each rAd-p53 injection, patients were given intracavitary administration of cisplatin 60 mg/m(2). This administration procedure continued once a week for 4 weeks. The control group (n = 21) received the same intracavitary therapy as the treatment group but without rAd-p53 therapy. Efficacy was evaluated by clinical observations, computed tomography, tumour markers, Karnofsky score and short-term follow-up. The total effective rates for the treatment group (63.0%) were significantly higher than for the control group (42.9%), suggesting that the treatment group benefited over the control group. In conclusion, rAd-p53 therapy is a safe and effective treatment for advanced malignant pleural or peritoneal effusion.

Automating fruit fly Drosophila embryo injection for high throughput transgenic studies

To decipher and manipulate the 14 000 identified Drosophila genes, there is a need to inject a large number of embryos with transgenes. We have developed an automated instrument for high throughput injection of Drosophila embryos. It was built on an inverted microscope, equipped with a motorized xy stage, autofocus, a charge coupled device camera, and an injection needle mounted on a high speed vertical stage. A novel, micromachined embryo alignment device was developed to facilitate the arrangement of a large number of eggs. The control system included intelligent and dynamic imaging and analysis software and an embryo injection algorithm imitating a human operator. Once the injection needle and embryo slide are loaded, the software automatically images and characterizes each embryo and subsequently injects DNA into all suitable embryos. The ability to program needle flushing and monitor needle status after each injection ensures reliable delivery of biomaterials. Using this instrument, we performed a set of transformation injection experiments. The robot achieved injection speeds and transformation efficiencies comparable to those of a skilled human injector. Because it can be programed to allow injection at various locations in the embryo, such as the anterior pole or along the dorsal or ventral axes, this system is also suitable for injection of general biochemicals, including drugs and RNAi.

Structural basis of natural ligand binding and activation of the Class II G-protein-coupled secretin receptor

The secretin receptor is prototypic of Class II GPCRs (G-protein-coupled receptors), based on its structural and functional characteristics and those of its natural agonist ligand. Secretin represents a linear 27-residue peptide with diffuse pharmacophoric domain. The secretin receptor includes the typical signature sequences for this receptor family within its predicted transmembrane segments and the highly conserved six cysteine residues contributing to three intradomain disulfide bonds within its long N-terminus. This domain is critical for secretin binding based on receptor mutagenesis and photoaffinity labelling studies. Full agonist analogues of secretin incorporating a photolabile moiety at various positions throughout the pharmacophore covalently label residues within this region, while only N-terminal probes have labelled the core helical bundle domain. Combining insights coming from receptor structural studies, peptide structure-activity relationship considerations, photoaffinity labelling, and application of fluorescence techniques has resulted in the development of a working model of the secretin-receptor complex. This supports the initial docking of the peptide agonist within a cleft in the receptor N-terminus, providing the opportunity for an endogenous sequence within that domain to interact with the core of the receptor. This interaction is believed to be key in the molecular basis of conformational change associated with activation of this receptor. The site of action of this endogenous agonist could also provide a possible target for small molecule agonists to act.

Expression of HSP70 and JNK-related proteins in human liver cancer: Potential effects on clinical outcome

BACKGROUND

Activation of stress-activated protein kinase/c-Jun N-terminal kinase was inhibited in cells, in which heat shock protein70 was induced to a high level, indicating that heat shock protein70 might be anti-apoptosis protein.

AIM

We examined the expression of heat shock protein70 and c-Jun N-terminal kinase signal transduction pathway in human liver carcinoma to explore their relationship and clinical parameters.

PATIENTS AND METHODS

The expression of heat shock protein70, c-Jun N-terminal kinase1, c-Jun N-terminal kinase2 and c-Jun were detected immunohistochemically in 62 samples of liver cancer. Western blot was used to confirm immunostaining results.

RESULTS

Heat shock protein70 expression showed a positive correlation with the malignant differentiation in liver carcinoma (r=0.449, P<0.0005). The expression of c-Jun N-terminal kinase1, c-Jun N-terminal kinase2, and c-Jun showed a negative correlation with the malignant differentiation in liver carcinoma (r=-0.351, P=0.005; r=-0.303, P=0.017; r=-0.302, P=0.017). Heat shock protein70 expression was correlated with c-Jun N-terminal kinase1 (r=-0.385, P=0.002), c-Jun N-terminal kinase2 (r=-0.309, P=0.015) and c-Jun (r=-0.302, P=0.017). Expression of heat shock protein70, as well as c-Jun N-terminal kinase1, was correlated with recurrence-free survival after the resection. Heat shock protein70 was associated with prognosis (P=0.004).

CONCLUSION

Expression of heat shock protein70 and c-Jun N-terminal kinase-related proteins might be an indicator of malignant potential in liver carcinoma. The balance between heat shock protein70 and c-Jun N-terminal kinase-related protein may increase the stability of liver cancer cells in stress. Negative expression of heat shock protein70 might be a protective factor of recurrence of liver carcinoma.

Expression of the T cell receptor Vbeta repertoire in a human T cell resistant to asbestos-induced apoptosis and peripheral blood T cells from patients with silica and asbestos-related diseases

To explore the effects of asbestos and silica on the human immune system, an experimental model of low-dose and long-term exposure was established using a human HTLV-1-immortalized polyclonal T cell line, MT-2 (MT-2Org). MT-2 cells were continuously exposed to asbestos at a concentration (10 microg/ml) which does not induce complete cell death during short-term exposure. After acquiring resistance to CB-induced apoptosis (designated MT-2Rst), an immunological comparison was made between the MT-2Org and MT-2Rst lines in terms of T cell receptor-Vbeta (TcR-Vbeta) expression. MT-2Rst cells showed excess expression of various TcR-Vbeta, although TcR-Vbeta-overpresenting cells were characterized as undergoing apoptosis due to first contact with CB. Patients with asbestos-related diseases (ARD), such as asbestosis and malignant mesothelioma, were compared with silicosis (SIL) patients as a disease control and with healthy donors (HD). SIL and ARD not only differed in their causative materials, silica and asbestos as mineral silicates, but also in terms of complications; autoimmune disorders in SIL and tumors in ARD. ARD patients showed a restricted overpresentation of TcR-Vbeta without clonal expansion, whereas SIL patients revealed significant overpresentation of TcR-Vbeta 7.2. These experimental and clinical analyses indicate the superantigenic and dysregulation of autoimmunity-inducing effects of asbestos and silica, respectively.

Risk assessment of organic pesticides pollution in surface water of Hangzhou

Advances in research on pollution of organic pesticides (OPs) in surface water, pollution survey and risk assessments of organochlorine pesticides (OCPs) and organophosphorus pesticides (OPPs) of surface water in Hangzhou are conducted. Total concentrations of dichloro-diphenyl-trichloroethane (DDT) and hexachloride-benzene (HCH) in surface water were observed to be 0-0.270 microg/L and 0-0.00625 microg/L respectively. DDE, as a metabolite of DDT and many species of OPP(S) were determined in some samples of surface water. Parathion, the main pollutant among OPPs in surface water of Hangzhou, was observed to be 0-0.445 microg/L. Based on these experimental results, health risk assessments on the organic pollution are developed. It is observed that the total risk "R (T)" at present time of surface water in Hangzhou is mainly contributed by organophosphorus pesticides, especially Parathion; HCH and DDT are not the main contaminants; on the contrary, organophosphorous pesticides, especially Parathion, must be of concern at the present time.

Analysis of Immiscible Water-Alternating-Gas (WAG) Injection Using Micromodel Tests

Abstract

In waterflooded reservoirs, it is possible to recover a significant amount of residual oil by enhanced oil recovery. Immiscible water-alternating-gas (WAG) injection is one of the well-established methods for improving oil recovery. However, the mechanism of three-phase flow in the process has not been well understood and prediction of the three-phase permeability has been highly uncertain.

This paper presents the results of immiscible WAG injection in a water-wet micromodel. During immiscible gas injection after an initial waterflood, gas moved through the residual oil paths, and residual oil was pushed either toward the production end of the model or into previously waterflooded channels. Breakthrough of gas occurred at about 0.25 PV for the micromodel used in this work. Further gas injection beyond the breakthough volume increased oil recovery only very slightly. When water was injected following gas injection, it flowed through channels that were created in the initial waterflood. Most of the residual oil that had been pushed into these waterflooded channels by the previous gas injection was produced. The mechanism of gas, oil, and water flow during immiscible WAG injection was analyzed. The observations and analysis provide insight into the flow behaviour of a three-phase system in the immiscible WAG process, which is important in the modelling of the process.

Introduction

A problem with gas injection (both miscible and immiscible) is the inherently unfavourable mobility ratio and the resulting poor volumetric sweep in reservoirs. Injection of gas as slugs alternated with water slugs, or water-alternating-gas (WAG), is the common practice presently used for controlling gas mobility. The WAG technique is indeed a combination of two oil recovery processes: gas injection and waterflood. However, the use of the combination of the two processes has resulted in some problems that have perplexed the industry since the pilot test studies were implemented in the early 1970s.

In the immiscible gas injection process, the portion of the injected gas dissolved in the oil reduces the oil viscosity. In addition to reducing viscosity, the dissolved gas also swells the oil, so for a given fixed residual oil saturation, less stock tank oil remains after a waterflood. These two mechanisms have been demonstrated by numerous laboratory PVT and coreflood tests. Laboratory coreflood experiments also showed that the free gas displacement is a very important mechanism for immiscible gas injection. Analysis of results from a tertiary CO2 injection field test revealed that incremental oil production by immiscible CO2 injection has two components(1). The first is an instantaneous response, probably resulting from gas displacing oil that was not being displaced by water. The second component is the long-term effect caused by viscosity reduction, swelling, and relative permeability alteration. The mechanism of instantaneous response, i.e., a sharp increase in the oil production rate during a CO2 slug injection, is still not well understood. Spival et al.(1) also realized that N2 contained in the CO2 stream is a complicating factor that reduces the solubility of CO2 in the oil and, on the other hand, may decrease the residual oil saturation by being trapped in the reservoir.

Determining the Most Profitable ASP Flood Strategy for Enhanced Oil Recovery

Abstract

While chemical floods have proven technically successful, the high cost of chemicals makes it challenging to develop a costeffective tertiary process. If high interfacial tension (IFT) exists between the oil and water phases, the resulting capillary forces will resist externally applied viscous forces. This could cause the injected water and chemicals to bypass the residual oil and go to waste.

The experimental studies presented here include reservoir fluid characterization, IFT measurements, and coreflood tests; all critical elements in designing a cost-effective alkaline/surfactant/ polymer (ASP) injection strategy. Coreflood tests used either sandpacks or composite reservoir cores with a selected medium crude oil. Injected surfactant concentration, slug size, chasing fluid, and residual oil saturation were the varied parameters. The optimal surfactant concentration of 0.15 wt% and slug size of 0.5 pore volume (PV) obtained relatively high oil recovery while maintaining a favourably high displacement efficiency ratio. Incremental recovery was 23 – 41% initial oil-in-place (IOIP) in sandpack tests and about 16% IOIP with reservoir cores. Overall, these coreflood results indicate that ASP flooding is a suitable enhanced oil recovery method for medium oil if the right chemical concentration and slug size are selected.

Introduction

The use of ASP flooding to recover oil left behind by waterflooding has become more common in recent years. Several significant developments have made ASP flooding a viable option for field enhanced oil recovery (EOR) projects and more attractive than polymer or micellar/polymer flooding. First, because world oil consumption continues to grow while production in many mature fields continues to decline, oil prices are predicted to stabilize above US$20/bbl. Second, newly developed cheaper surfactants have reduced the cost of EOR formulations by 40 to 60%, while maintaining the same high oil recoveries obtained using more expensive surfactants. The incremental cost per barrel of oil produced has been reduced to a reasonable level, between US$1.44 and $5.83(1). Third, chemical flooding can be evaluated in the oil field faster and more economically than in the past using the single-well EOR pilot test and field-scale numerical simulations. Fourth, waterfloods in most mature reservoirs have experienced early water breakthrough and have reached their economic limit. Therefore, oil companies have to consider applying new EOR technologies to increase recovery factors in such fields.

The proven medium oil resource in southwest Saskatchewan, estimated at 534.5 × 106 m3, is located in reservoirs characterized by thin pay and shaly sand. Primary and secondary methods have recovered an estimated 25% IOIP from these reservoirs(2) and are nearing their economic limit. There has been little development of this resource by EOR technologies.

The Saskatchewan Research Council (SRC) has conducted extensive studies to develop ASP flooding for a selected reservoir- Instow-with reserves of about 22.1 × 106 m3 of medium oil originally in place. Instow field is located in Ranges 18 and 19 of Townships 9 and 10 in southwest Saskatchewan. This moderate- permeability sandstone reservoir (Upper Shaunavon sand at a depth of 1,370 m) was discovered in 1954 and has been waterflooded since 1959.

Alkaline/Surfactant/Polymer (ASP) Flood Potential in Southwest Saskatchewan Oil Reservoirs

Abstract

Most of the medium oil reservoirs in southwest Saskatchewan are in thin pay zones of less than 8 m. Primary and waterflood methods have reached more than 80% of their estimated oil recovery potential. These medium oil reservoirs are basically untouched by enhanced oil recovery techniques.

An initial study was conducted to assess the suitability of Alkaline/Surfactant/Polymer (ASP) flooding for southwest Saskatchewan reservoirs. On the basis of screening criteria in the literature, the region's reservoir conditions, except for some of the formation types, are favourable for ASP flooding. If only sandstone formations are considered for this process, about 49% of the pools in the region are good candidates for ASP flooding. Extensive oil/water interfacial tension and viscosity measurements were taken using screening criteria for surfactant, alkaline, and polymers. A series of sandpack flood tests were conducted in sandpacks to evaluate ASP flooding for the oil. A tertiary oil recovery of 39% IOIP (72% ROIP) was obtained for the test using all three chemicals. These sandpack flood test results showed that a synergistic enhancement among the chemicals did occur in the ASP system for the medium oil with a very low acid number. The results also indicated that, for a medium oil, mobility control was essential and selection of the right surfactant was important.

Introduction

Oil reservoirs located in southwest Saskatchewan, with 3.1 billion barrels of proven oil, are characterized by thin pay (2 to 8 m in thickness) and shaley sand. The estimated oil recovery by primary and secondary methods from these reservoirs is about 25% initial oil in place (IOIP)(1). Waterfloods in most of these reservoirs have experienced early water breakthrough and high water cut due to the high oil-to-water viscosity ratio. For some of these reservoirs, waterfloods have nearly reached their economic limit. For achieving additional oil recovery and subsequent financial benefits, the development of an enhanced oil recovery technique is essential.

Chemical-enhanced oil recovery methods mainly include micellar/polymer flooding, alkaline flooding, polymer flooding, and combinations of two or all of the three methods. Extensive studies of these processes have found that successful chemical flooding needs to be able to efficiently lower the oil/water interfacial tension and to have very good mobility control.

The displacement mechanism of an ASP flood is similar to that of micellar/polymer flooding except that much of the surfactant is replaced by low-cost alkali. Therefore, the overall cost is lower even though the chemical slugs can be larger. Polymer is usually incorporated in the larger, dilute slug. It has been recognized that oil recovery can be greatly improved by the synergism of chemicals used in the ASP formulations.

ASP processes are also being tested in the field. A field-wide project in Wyoming reports costs of US$10 to $22/tonne (US$1.6 – 3.5/bbl) of incremental oil produced(2). The economic analysis of two ASP pilot tests in the Daqing oil field, China, showed that the chemical cost was US$21 to $28/tonne (US$3 – 4/bbl) of incremental oil produced(3).

An experimental investigation of retention of liquids in corners of a square capillary

The retention of liquids in the corners of a 0.03-cm square capillary after the passage of a gas slug was studied experimentally as a function of capillary number in the range from 10(-3) to 10(-6). In gas-wetting liquid systems, for capillary number greater than 5 x 10(-4), the retention of a wetting liquid in the corners showed a strong dependence on the capillary number; i.e., the retention of the liquid decreased with decreasing capillary number. For capillary number less than 10(-4), the retention of a wetting liquid was found to be determined by the capillary forces and the rate (or viscous) effect was negligible. In gas-oil-water systems involving double displacements--gas was displacing oil which was in turn displacing water--the total retention of water and oil vs capillary number curve showed the same trend as the retention of a wetting phase in a gas-wetting liquid system. However, because of the viscous effect, the water retention showed a continuous decrease with decreasing capillary number and could be lower than the capillary equilibrium value at very low capillary numbers. As a result of this, the oil retention vs capillary number curve in the double displacement process showed a minimum; i.e., oil retention increased with decreasing capillary number in the range of very low capillary numbers.

Steroidal saponins from Dioscorea panthaica and their cytotoxic activity

A new steroidal saponin, dioscoreside E (1), and a known compound, protodioscin (2), were isolated from an ethanol extract of the rhizomes of Dioscorea panthaica. The structure of 1 was established as 3-O-[bis-alpha-L-rhamnopyranosyl-(1 --> 2 and 1 --> 4)-beta-D-glucopyranosyl]-26-O-beta-D-glucopyranosyl-20(R)-methoxy-25(R)-furosta-5,22(23)-diene-3beta,26-diol, on the basis of spectral and chemical evidence. Compounds 1 and 2 showed cytotoxic activity against a panel of tumor cell lines.

Oil Layer Flow Along the Corners of Non- Circular Capillaries by Gravity Drainage

Abstract

The fundamentals of oil layer drainage along the corners of non-circular capillaries in two-phase (gas-oil) and three-phase (gas-oil-water) systems were studied. Experiments of oil layer flow along the corners of square capillaries were carried out to investigate the saturation dependency of oil phase relative permeability in single layer drainage. The quadratic behaviour of oil relative permeability in the gas injection process reported in the literature was explained. For double-layer flow (water layer and oil layer) in a three-phase system, numerical analysis showed that the lubricating effect of a water layer on the relative permeability of oil phase in layer drainage was significant. The dependency of oil layer flow by gravity drainage on oil saturation, water saturation, and oil-to-water viscosity ratio was investigated numerically. The experimental results confirmed the mathematical analysis.

Introduction

Both laboratory experimental results and oil field performance analysis have demonstrated that very high oil recoveries of residual oil can be achieved if gravity drainage is the dominant production mechanism(1–4). Because of the importance of the oil relative permeability in the process of gravity drainage, extensive studies have been conducted on the measurement and analysis of threephase relative permeability.

Numerous measurements have been carried out to determine the three-phase relative permeability during the gravity drainage process(4). It was found that a quadratic change of oil relative permeability with respect to the oil saturation is followed if:the porous medium is water-wet;oil flows in layers; andwater flow is negligible.

Oil layer drainage is an important recovery mechanism in a gravity assisted gas injection process and other enhanced oil recovery methods such as steam assisted gravity drainage (SAGD) and vapour extraction process (VAPEX). To develop physically sound modelling capabilities for these processes, a better understanding of the fundamentals of oil layer flow is necessary at both the microscopic level and the macroscopic level. The results of this study can help improve the understanding and modelling of the oil phase flow in porous media in SAGD, VAPEX, and other gravity assisted gas injection processes.

Single Layer Drainage

In this instance, the procedure to measure the accumulation of wetting liquid by gravity drainage was essentially that of Chatzis, et al.(3) The oils used were heptane and Soltrol 170. At experimental temperature (23 ° C), heptane had a viscosity of 1.0 mPa.s and a density of 0.69 g/cm3, whereas Soltrol 170 had a viscosity of 3.0 mPa.s and a density of 0.70 g/cm3.

The flow rate of liquid in single layer drainage along the four corners of a square capillary under steady-state condition is expressed as follows(5):

Equation 1 (available in full paper)

where S is the saturation of the liquid in the tube, D is the size of the square capillary, and β?is the dimensionless resistance coefficient. If the saturation of the wetting liquid in two square capillaries of different sizes is the same, the layer drainage rate is proportional to the tube size raised to the fourth power.

Coreflood Studies of Tertiary CO2 Flood in Naturally Fractured Midale Formation in Southeast Saskatchewan

Abstract

The distinctive geology of the Weyburn and Midale reservoirs has important implications for the design of a CO2 injection process for these fields. They are contained within two distinct zones of the Mississippian Carbonate formation; the tight, high-porosity Marly zone sits on top of the low-porosity Vuggy zone. The latter zone has a higher permeability, and is more extensively fractured vertically, than the Marly zone. These geological features result in a relatively unswept Marly zone after waterflooding. The Marly/Vuggy sequence presents an opportunity for a CO2 flood to take advantage of gravity segregation to recover the large remaining oil target in the Marly zone.

A series of coreflood tests were conducted to simulate tertiary CO2 injection in the Marly/Vuggy zones in the Weyburn and Midale reservoirs. Berea cores with different permeabilities were split lengthwise. The halved segments of the core were butted together to represent the Marly and Vuggy zones. Water (in waterflood mode) and CO2 (in tertiary CO2 flood mode) were injected into the bottom high-permeability section of the dualpermeability core. The coreflood results showed that, in the tertiary CO2 flood, CO2 could migrate to and recover the oil from the top low-permeability zone which was poorly swept by the waterflood. Also, the effects on tertiary oil recovery of operating pressure, injection rate, and permeability contrast could be significant.

Introduction

The Weyburn and Midale reservoirs in southeast Saskatchewan hold light and medium gravity oil in fractured, low permeability Midale Beds. These reservoirs are contained within two distinct zones of the Mississippian Carbonate formation: the tight, highporosity Marly zone sits on top of the low-porosity Vuggy zone. The latter zone has a higher permeability, and is more extensively fractured vertically than the Marly zone. These geological features result in a relatively unswept Marly zone after waterflooding.

It is believed that the distinctive geology of these reservoirs has important implications for the design of a CO2 injection process for these fields, i.e., the Marly-Vuggy arrangement of the reservoir offers potential to utilize gravity segregation effects to enhance oil recovery. Numerical analyses(1, 2) of tertiary CO2 injection in these naturally fractured reservoirs showed that CO2 injected into the lower, more permeable Vuggy zone can contact and mobilise a large amount of oil in the Marly, which has remained relatively unaccessed by waterflooding.

A coreflood program was designed at Saskatchewan Research Council (SRC) to address the CO2 injection process in Weyburn reservoir and comparable fields. Laboratory core displacement tests were conducted with a dual permeability split Berea core representing the Marly and Vuggy zones of a reservoir. Some preliminary results reported in a previous paper(3) showed that CO2 injected into the Vuggy zone could rise to the upper Marly zone, and that the potential to recover incremental oil by a tertiary CO2 slug flood is high. After the technique of butting the core halves was improved, the several additional tertiary CO2 coreflood tests reported here were performed with Weyburn reservoir fluid at 63 ° C (reservoir temperature) to confirm the previous finding.

Apoptosis, proliferation and p53 gene expression of H. pylori associated gastric epithelial lesions

AIM: To study the relationship between Helicobacter pylori (H. pylori) and gastric carcinoma and its possible pathogenesis by H. pylori.

METHODS: DNEL technique and immunohistochemical technique were used to study the state of apoptosis, proliferation and p53 gene expression. A total of 100 gastric mucosal biopsy specimens, including 20 normal mucosa, 30 H. pylori-negative and 30 H. pylori-positive gastric precancerous lesions along with 20 gastric carcinomas were studied.

RESULTS: There were several apoptotic cells in the superficial epithelium and a few proliferative cells within the neck of gastric glands, and no p53 protein expression in normal mucosa. In gastric carcinoma, there were few apoptotic cells, while there were a large number of proliferative cells, and expression of p53 protein significantly was increased. In the phase of metaplasia, the apoptotic index (AI, 4.36% ± 1.95%), proliferative index (PI, 19.11% ± 6. 79%) and positivity of p53 expression (46.7%) in H. pylori-positive group were higher than those in normal mucosa (P < 0.01). AI in H. pylori-positive group was higher than that in H. pylori-negative group (3.81% ± 1.76%), PI in H. pylori-positive group was higher than that in H. pylori-negative group (12.25% ± 5.63%, P < 0.01). In the phase of dysplasia, AI (2.31% ± 1.10%) in H. pylori-positive group was lower (3.05% ± 1.29%) than that in H. pylori-negative group, but PI (33.89% ± 11.65%) was significantly higher (22.09% ± 80.18%, P < 0.01). In phases of metaplasia, dysplasia and gastric cancer in the H. pylori-positive group, AIs had an evidently graduall decreasing trend (P < 0.01), while PIs had an evidently gradual increasing trend (P < 0.05 or P < 0.01), and there was also a trend of gradual increase in the expression of p53 gene.

CONCLUSION: In the course of the formation of gastric carcinoma, proliferation of gastric mucosa can be greatly increased by H. pylori, and H. pylori can induce apoptosis in the phase of metaplasia, but in the phase of dysplasia H. pylori can inhibit cellular apoptosis. And H. pylori infection can strengthen the expression of mutated p53 gene.

Two new steroidal saponins from the rhizomes of Dioscorea panthaica and their cytotoxic activity

Two new steroidal saponins, dioscoresides C (1) and D (2), along with a new natural product, pregnadienolone 3-O-beta-gracillimatriose (3), and two known compounds, pregnadienolone 3-O-beta-chacotrioside (4) and pseudoprotodioscin (5), were isolated from the rhizomes of Dioscorea panthaica Prain et Burkill. On the basis of extensive NMR studies and chemical evidence, dioscoresides C and D were determined to be 26-O-beta-D-glucopyranosyl-3 beta,26-dihydroxy-23(S)-methoxy-25(R)-furosta-5,20(22)-dien-3-O-alpha-L-rhamnopyranosyl-(1-->2)-[alpha-L-rhamnopyranosyl-(1-->4)]-beta-D-glucopyranoside and 26-O-beta-D-glucopyranosyl-3 beta,26-dihydroxy-20,22-seco-25(R)-furosta-5-en-20,22-dine-3-O-alpha-L-rhamnopyranosyl-(1-->2)-[alpha-L-rhamnopyranosyl-(1--> 4)]-beta-D-glucopyranoside. These compounds showed mild cytotoxicity against the cancer cell lines, A375, L929, and HeLa, in a dose-dependent manner.

Increased nitric oxide in peritoneal fluid from women with idiopathic infertility and endometriosis

OBJECTIVE

To verify whether nitric oxide in peritoneal fluid is associated with endometriosis and infertility.

STUDY DESIGN

Twenty-five women with idiopathic infertility and 38 with endometriosis were recruited, and 18 cases of uterine myomata and 2 cases of ovarian cyst served as controls. Peritoneal fluid samples were aspirated from the pouch of Douglas during laparoscopy or laparotomy. Metabolites of nitric oxide (nitrite and nitrate) in peritoneal fluid were determined by a method using nitrate reductase and the Griess reaction.

RESULTS

Peritoneal concentrations of nitrate/nitrite in both infertile women (42.02 +/- 12.98 mmol/L) and patients with endometriosis (41.75 +/- 16.42 mmol/L) were significantly higher than that in controls (33.96 +/- 13.07, P < .05 for both). No significant difference in peritoneal nitrate/nitrite level was found between infertile women and patients with endometriosis (P > .5). Peritoneal levels of nitrate/nitrite were comparable among patients with endometriosis at different stages (P > .5). Patients with endometriosis had more peritoneal fluid than controls and idiopathic infertile women, while controls and idiopathic infertile women had comparable amounts of peritoneal fluid.

CONCLUSION

An increased peritoneal level of nitric oxide is a common alteration in endometriosis, endometriosis-associated infertility and idiopathic infertility and may be associated with the pathogenesis of these diseases.

Identification of peptide ligand-binding domains within the human motilin receptor using photoaffinity labeling

The cDNA encoding the human motilin receptor was recently cloned and found to represent a G protein-coupled receptor that is structurally related to the growth hormone secretagogue receptors. Together, these represent a new Class I receptor family. Our aim in the present work is to gain insight into the molecular basis of binding of motilin to its receptor using photoaffinity labeling. To achieve this, we developed a Chinese hamster ovary cell line that overexpressed functional motilin receptor (CHO-MtlR; 175,000 sites per cell, with K(i) = 2.3 +/- 0.4 nm motilin and EC(50) = 0.3 +/- 0.1 nm motilin) and a radioiodinatable peptide analogue of human motilin that incorporated a photolabile p-benzoyl-l-phenylalanine (Bpa) residue into its pharmacophoric domain. This probe, [Bpa(1),Ile(13)]motilin, was a full agonist at the motilin receptor that increased intracellular calcium in a concentration-dependent manner (EC(50) = 1.5 +/- 0.4 nm). This photolabile ligand bound specifically and with high affinity to the motilin receptor (K(i) = 12.4 +/- 1.0 nm), and covalently labeled that molecule within its M(r) = 45,000 deglycosylated core. Cyanogen bromide cleavage demonstrated its covalent attachment to fragments of the receptor having apparent M(r) = 6,000 and M(r) = 31,000. These were demonstrated to represent fragments that included both the first and the large second extracellular loop domains, with the latter representing a unique structural feature of this receptor. The spatial approximation of the pharmacophoric domain of motilin with these receptor domains support their functional importance as well.

Influence of growth hormone-insulin-like growth factor I axis on normal pregnancy

OBJECTIVE

To investigate the role of growth hormone-insulin-like growth factor I (IGF-I) axis in normal pregnancy.

METHODS

Totally, 116 normal pregnant women were recruited from January 1997 to June 1998, with 20 normal nonpregnant women as controls. Maternal growth hormone (GH) and IGF-I concentrations were assayed by RIA and enzyme-linked immunosorbent assay, respectively.

RESULTS

Maternal serum levels of GH increased throughout gestation, reached a peak at 25 weeks of pregnancy and remained fairly high (chi 2 = 40.458, P < 0.0001). There was a significant difference between samples at 5-9 week gestational age and the controls (3.45 micrograms/L vs 1.61 micrograms/L, P < 0.05). The maternal serum levels of IGF-I increased rapidly throughout gestation from 29-week gestation and reached a peak of 188.86 micrograms/L at term delivery (chi 2 = 50.224, P < 0.0001).

CONCLUSIONS

Maternal GH levels increased progressively throughout gestation, which correlated with fetal growth. Maternal GH may regulate nutrition supply among mother, placenta and the fetus and play an important role in transporting nutritional substrates by the placenta. The maternal IGF-I in the third trimester may promote fetal growth and placental functions.