The genome of black cottonwood, Populus trichocarpa (Torr. & Gray)

We report the draft genome of the black cottonwood tree, Populus trichocarpa. Integration of shotgun sequence assembly with genetic mapping enabled chromosome-scale reconstruction of the genome. More than 45,000 putative protein-coding genes were identified. Analysis of the assembled genome revealed a whole-genome duplication event; about 8000 pairs of duplicated genes from that event survived in the Populus genome. A second, older duplication event is indistinguishably coincident with the divergence of the Populus and Arabidopsis lineages. Nucleotide substitution, tandem gene duplication, and gross chromosomal rearrangement appear to proceed substantially more slowly in Populus than in Arabidopsis. Populus has more protein-coding genes than Arabidopsis, ranging on average from 1.4 to 1.6 putative Populus homologs for each Arabidopsis gene. However, the relative frequency of protein domains in the two genomes is similar. Overrepresented exceptions in Populus include genes associated with lignocellulosic wall biosynthesis, meristem development, disease resistance, and metabolite transport.

Pro-caspase-3 is a major physiologic target of caspase-8

The apoptotic signal triggered by ligation of members of the death receptor family is promoted by sequential activation of caspase zymogens. We show here that in a purified system, the initiator caspases-8 and -10 directly process the executioner pro-caspase-3 with activation rates (kcat/Km) of 8.7 x 10(5) and 2.8 x 10(5) M-1 s-1, respectively. These rates are of sufficient magnitude to indicate direct processing in vivo. Differentially processed forms of caspase-3 that accumulate during its activation have similar rates of activation, activities, and specificities. The pattern and rate of caspase-8 induced activation of pro-caspase-3 in cytosolic extracts was the same as in a purified system. Moreover, immunodepletion of a putative intermediary in the pathway to activation, pro-caspase-9, was without consequence. Taken together these data demonstrate that the initiator caspase-8 can directly activate pro-caspase-3 without the requirement for an accelerator. The in vitro data thus help to deconvolute previous in vivo transfection studies which have debated the role of a direct versus indirect transmission of the apoptotic signal generated by ligation of death receptors.

The dependence receptor DCC (deleted in colorectal cancer) defines an alternative mechanism for caspase activation

The expression of DCC (deleted in colorectal cancer) is often markedly reduced in colorectal and other cancers. However, the rarity of point mutations identified in DCC coding sequences and the lack of a tumor predisposition phenotype in DCC hemizygous mice have raised questions about its role as a tumor suppressor. DCC also mediates axon guidance and functions as a dependence receptor; such receptors create cellular states of dependence on their respective ligands by inducing apoptosis when unoccupied by ligand. We now show that DCC drives cell death independently of both the mitochondria-dependent pathway and the death receptor/caspase-8 pathway. Moreover, we demonstrate that DCC interacts with both caspase-3 and caspase-9 and drives the activation of caspase-3 through caspase-9 without a requirement for cytochrome c or Apaf-1. Hence, DCC defines an additional pathway for the apoptosome-independent caspase activation.

TRAF family proteins interact with the common neurotrophin receptor and modulate apoptosis induction

The common neurotrophin receptor, p75(NTR), has been shown to signal in the absence of Trk tyrosine kinase receptors, including induction of neural apoptosis and activation of NF-kappaB. However, the mechanisms by which p75(NTR) initiates these intracellular signal transduction pathways are unknown. Here we report interactions between p75(NTR) and the six members of TRAF (tumor necrosis factor receptor-associated factors) family proteins. The binding of different TRAF proteins to p75(NTR) was mapped to distinct regions in p75(NTR). Furthermore, TRAF4 interacted with dimeric p75(NTR), whereas TRAF2 interacted preferentially with monomeric p75(NTR). TRAF2-p75(NTR), TRAF4-p75(NTR), and TRAF6-p75(NTR) interactions modulated p75(NTR)-induced cell death and NF-kappaB activation with contrasting effects. Coexpression of TRAF2 with p75(NTR) enhanced cell death, whereas coexpression of TRAF6 was cytoprotective. Furthermore, overexpression of TRAF4 abrogated the ability of dimerization to prevent the induction of apoptosis normally mediated by monomeric p75(NTR). TRAF4 also inhibited the NF-kappaB response, whereas TRAF2 and TRAF6 enhanced p75(NTR)-induced NF-kappaB activation. These results demonstrate that TRAF family proteins interact with p75(NTR) and differentially modulate its NF-kappaB activation and cell death induction.

Transformation of Medicago truncatula via infiltration of seedlings or flowering plants with Agrobacterium

Two rapid and simple in planta transformation methods have been developed for the model legume Medicago truncatula. The first approach is based on a method developed for transformation of Arabidopsis thaliana and involves infiltration of flowering plants with a suspension of Agrobacterium. The second method involves infiltration of young seedlings with Agrobacterium. In both cases a proportion of the progeny of the infiltrated plants is transformed. The transformation frequency ranges from 4.7 to 76% for the flower infiltration method, and from 2.9 to 27.6% for the seedling infiltration method. Both procedures resulted in a mixture of independent transformants and sibling transformants. The transformants were genetically stable, and analysis of the T2 generation indicates that the transgenes are inherited in a Mendelian fashion. These transformation systems will increase the utility of M. truncatula as a model system and enable large-scale insertional mutagenesis. T-DNA tagging and the many adaptations of this approach provide a wide range of opportunities for the analysis of the unique aspects of legumes.

Glioma: Application of histogram analysis of pharmacokinetic parameters from T1-weighted dynamic contrast-enhanced MR imaging to tumor grading

BACKGROUND AND PURPOSE

The usefulness of pharmacokinetic parameters for glioma grading has been reported based on the perfusion data from parts of entire-tumor volumes. However, the perfusion values may not reflect the entire-tumor characteristics. Our aim was to investigate the feasibility of glioma grading by using histogram analyses of pharmacokinetic parameters including the volume transfer constant, extravascular extracellular space volume per unit volume of tissue, and blood plasma volume per unit volume of tissue from T1-weighted dynamic contrast-enhanced perfusion MR imaging.

MATERIALS AND METHODS

Twenty-eight patients (14 men, 14 women; mean age, 49.75 years; age range, 25-72 years) with histopathologically confirmed gliomas (World Health Organization grade II, n = 7; grade III, n = 8; grade IV, n = 13) were examined before surgery or biopsy with conventional MR imaging and T1-weighted dynamic contrast-enhanced perfusion MR imaging at 3T. Volume transfer constant, extravascular extracellular space volume per unit volume of tissue, and blood plasma volume per unit volume of tissue were calculated from the entire-tumor volume. Histogram analyses from these parameters were correlated with glioma grades. The parameters with the best percentile from cumulative histograms were identified by analysis of the area under the curve of the receiver operating characteristic analysis and were compared by using multivariable stepwise logistic regression analysis for distinguishing high- from low-grade gliomas.

RESULTS

All parametric values increased with increasing glioma grade. There were significant differences among the 3 grades in all parameters (P < .01). For the differentiation of high- and low-grade gliomas, the highest area under the curve values were found at the 98th percentile of the volume transfer constant (area under the curve, 0.912; cutoff value, 0.277), the 90th percentile of extravascular extracellular space volume per unit volume of tissue (area under the curve, 0.939; cutoff value, 19.70), and the 84th percentile of blood plasma volume per unit volume of tissue (area under the curve, 0.769; cutoff value, 11.71). The 98th percentile volume transfer constant value was the only variable that could be used to independently differentiate high- and low-grade gliomas in multivariable stepwise logistic regression analysis.

CONCLUSIONS

Histogram analysis of pharmacokinetic parameters from whole-tumor volume data can be a useful method for glioma grading. The 98th percentile value of the volume transfer constant was the most significant measure.

A new pH sensitive fluorescent and white light emissive material through controlled intermolecular charge transfer

A new, pH dependent and water-soluble, conjugated oligomer (amino, trimethylammonium oligophenylene vinylene, ATAOPV) was synthesized with a quaternary ammonium salt and an aromatic amine at the two ends of a π-conjugated oligomer, thus creating a strong dipole across the molecule. A unique white light LED is successfully fabricated from a stimuli responsive organic molecule whose emission properties are dominated by the pH value of the solution through controlled intermolecular charge transfer.

Involvement of NF-kappa B activation in thrombin-induced human vascular smooth muscle cell proliferation

A thrombin receptor has been cloned and is thought to mediate a variety of thrombin-induced responses. However, the transcription factors important for postreceptor signaling have been little clarified. The post-receptor signals are mediated by several protein kinases responsible for NF-kappa B activation, and most thrombin-inducible genes have the kappa B sequence in the regulatory elements. The possibility that NF-kappa B may participate in thrombin signaling was therefore investigated in cultured human vascular smooth muscle cells (VSMCs). Thrombin receptor stimulation resulted in activation of NF-kappa B. Furthermore, treatment of cells with antisense p65 ODNs of NF-kappa B inhibited thrombin-stimulated growth of VSMC in vitro. Results indicate that the activation of NF-kappa B is involved in thrombin signaling and that this pathway causes the proliferation of VSMC induced by thrombin. Therapeutic potential of antisense NF-kappa B ODNs for the treatment with atherosclerosis and restenosis is also indicated.

Modification of oligo(poly(ethylene glycol) fumarate) macromer with a GRGD peptide for the preparation of functionalized polymer networks

A novel macromer, oligo(poly(ethylene glycol) fumarate) (OPF), was synthesized by the reaction between poly(ethylene glycol) (PEG) of molecular weight 1000 (PEG 1.0K) and fumaryl chloride. The oligo(PEG fumarate) (OPF 1.0K) was modified with a peptide known to modulate cellular functions, Gly-Arg-Gly-Asp (GRGD), after being activated with 4-nitrophenyl chloroformate (NPC). The determined yield of the GRGD modification in 0.1 M sodium bicarbonate buffer of pH 8.3 was 83% as determined by NMR measurements. The OPF 1.0K and the OPF 1.0K modified with GRGD were cross-linked with an unsaturated biodegradable polyester, poly(propylene fumarate) (PPF), by photopolymerization. The cross-linked PPF was characterized by Fourier transform infrared (FT-IR) spectroscopy and contact angle measurements. The equilibrium contact angle of water on the cross-linked PPF surface decreased with the incorporation of OPF 1.0K and the OPF 1.0K modified with GRGD. The results suggest that the OPF macromer can be used for the preparation of functionalized networks incorporating cell adhesion specific sequences.

Comparison between sitagliptin as add-on therapy to insulin and insulin dose-increase therapy in uncontrolled Korean type 2 diabetes: CSI study

AIM

Individuals requiring insulin therapy for type 2 diabetes often require escalation of their regimen to achieve glycaemic control. Optimal management strategies for uncontrolled type 2 diabetes would improve glycaemic control without hypoglycaemia and weight gain. This study compared the efficacy and tolerability of adding sitagliptin, an oral dipeptidyl peptidase-4 inhibitor, and an up to 20% increase in insulin dose in patients with uncontrolled type 2 diabetes on insulin therapy.

METHODS

We conducted a 24-week, randomized, active-competitor, parallel-group study in subjects with uncontrolled type 2 diabetes [haemoglobin A1c (HbA1c) = 7.5-11%] currently using insulin therapy. Subjects were randomly assigned to either the sitagliptin adding (100 mg daily, n = 70) or an insulin-increasing arm (≥ 10% at week 12 and ≥ 10% at week 24, n = 70) while continuing other medications.

RESULTS

Average baseline HbA1c was 9.2% in both groups. HbA1c decreased more at 24 weeks in the sitagliptin adding than the insulin-increasing arm (-0.6 ± 0.1% vs. -0.2 ± 0.1%, p < 0.01). Insulin was increased by 25% at 24 weeks in the insulin-increasing group. Hypoglycaemic events were less common and less severe in sitagliptin adding arm than insulin-increasing arm (7.0 vs. 14.3 events per patient-year, p < 0.05). Weight was stable in the sitagliptin adding subjects (68.6 ± 11.6 vs. 68.1 ± 11.4 kg) but increased in the insulin-increasing subjects (66.2 ± 10.6 vs. 67.4 ± 9.7 kg, p < 0.05). Other adverse events occurred at similar rates in both arms.

CONCLUSIONS

Compared to a 25% increase in insulin dose, adding sitagliptin to an insulin-based regimen was more effective at lowering HbA1c and associated with less hypoglycaemia and weight gain over 24 weeks.

CLINICAL TRIAL NUMBER

NCT01100125.

GTPase activity and biochemical characterization of a recombinant cotton fiber annexin

A cDNA encoding annexin was isolated from a cotton (Gossypium hirsutum) fiber cDNA library. The cDNA was expressed in Escherichia coli, and the resultant recombinant protein was purified. We then investigated some biochemical properties of the recombinant annexin based on the current understanding of plant annexins. An "add-back experiment" was performed to study the effect of the recombinant annexin on beta-glucan synthase activity, but no effect was found. However, it was found that the recombinant annexin could display ATPase/GTPase activities. The recombinant annexin showed much higher GTPase than ATPase activity. Mg2+ was essential for these activities, whereas a high concentration of Ca2+ was inhibitory. A photolabeling assay showed that this annexin could bind GTP more specifically than ATP. The GTP-binding site on the annexin was mapped into the carboxyl-terminal fourth repeat of annexin from the photolabeling experiment using domain-deletion mutants of this annexin. Northern-blot analysis showed that the annexin gene was highly expressed in the elongation stages of cotton fiber differentiation, suggesting a role of this annexin in cell elongation.

Photoplethysmography sampling frequency: pilot assessment of how low can we go to analyze pulse rate variability with reliability?

Pulse rate variability (PRV) analysis appears as the first alternative to heart rate variability analysis for wearable devices; however, there is a constraint on computational load and energy consumption for the limited system resources available to the devices. Considering that adjustment of the sampling frequency is one of the strategies for reducing computational load and power consumption, this study aimed to investigate the influence of sampling frequency (f _s) on PRV analysis and to find the minimum sampling frequency while maintaining reliability. We generated 5000, 2500, 1000, 500, 250, 100, 50, 25, 20, 15, 10, 5 Hz down-sampled photoplethysmograms from 10 kHz-sampled PPGs and derived time- and frequency-domain variables of the PRV. These included AVNN, SDNN, SDSD, RMSSD, NN50, pNN50, total power, VLF, LF, HF, LF/HF, nLF and nHF for each down-sampled signal. Derived variables were compared with heart rate variability of the 10 kHz-sampled electrocardiograms, and then statistically investigated using one-way ANOVA test and Bland-Altman analysis. As a result, significant differences (P  <  0.05) were found for SDNN, SDSD, RMSSD, NN50, pNN50, TP, HF, LF/HF, nLF and nHF, but not for AVNN, VLF and LF. Based on the post hoc tests, it was found that the NN50 and pNN50, SDSD and RMSSD, LF/HF and nHF, SDNN, TP and nLF analysis had significant differences at f _s  ⩽  20 Hz, f _s  ⩽  15 Hz, f _s  ⩽10 Hz; f _s  =  5 Hz, respectively. In other words, a significant difference was not seen for any variable if the f _s was greater than 25 Hz. Consequently, our pilot study suggests that analysis of variability in the time and frequency domain from pulse rate obtained through PPG may be potentially as reliable as that derived from the analysis of the electrocardiogram, provided that f _s  ⩾25 Hz sampling frequency is used.

Clinical features of vivax malaria

Plasmodium vivax malaria reemerged in the Republic of Korea in 1993 near the Demilitarized Zone (DMZ). We reviewed clinical features of 101 symptomatic patients with vivax malaria. Of the patients, 77 patients (76.3%) were veterans who had served near the DMZ; their median age was 23 years. The duration of the minimum latent period was > 6 months in 66.2% (51 of 77) of the patients (median, 278 days). Tertian fever developed in 69 patients (68.3%). Severe thrombocytopenia with platelet counts < 60,000/microL was common (29.6% of patients). The parasite densities ranged 32-52,127 parasites per microliter of blood (geometric mean, 1,287). The only complication was a splenic rupture in one patient. All patients responded promptly to chloroquine therapy. Our data suggest that the clinical features of reemerging vivax malaria may be similar to those of Korean vivax malaria reported in the past.

Patients with irritable bowel syndrome or constipation have an increased risk for ischaemic colitis

AIMS

To estimate the relative risk for ischaemic colitis in patients with and without irritable bowel syndrome or constipation, and to evaluate the role of irritable bowel syndrome and constipation as confounders in the relationship between commonly used gastrointestinal medications and ischaemic colitis.

METHODS

Patient cohorts were identified with the use of longitudinal MarketScan research databases from 1 January 1999 to 31 December 2002. Patients in each study cohort were matched 1:1 with comparable control patients using a propensity score. A Cox proportional hazards models were used to estimate relative risk for ischaemic colitis.

RESULTS

The relative risk for ischaemic colitis was 3.17 and 2.78 times higher for patients with irritable bowel syndrome and constipation, respectively, than for those without these disorders. Patients who were taking an antispasmodic, a proton pump inhibitor, or an H2-antagonist were at increased risk for ischaemic colitis [relative risk with 95% CI 2.73 (1.41-5.39), 2.00 (1.05-3.79), 2.75 (1.22-6.17) respectively]; however, when these results were adjusted for irritable bowel syndrome or constipation, the relative risks were attenuated and no longer statistically significant.

CONCLUSIONS

Patients with irritable bowel syndrome or constipation demonstrated a two- to threefold increased risk for ischaemic colitis. Moreover, irritable bowel syndrome and constipation strongly confounded the relationship between gastrointestinal drug use and the risk for ischaemic colitis, suggesting that etiologic studies of ischaemic colitis risk must account for the presence of irritable bowel syndrome or constipation.

Characteristic of InGaN/GaN Laser Diode Grown by a Multi-Wafer MOCVD System

InGaN/GaN multi-quantum well (MQW) laser diodes (LDs) were grown on c-plane sapphire substrates using a multi-wafer MOCVD system. The threshold current for pulsed lasing was 1.6 A for a gain-guided laser diode with a stripe of 10 × 800 μm2. The threshold current density was 20.3 kA cm−2 and the threshold voltage was 16.5 V. The optical power ratio of transverse electric mode to transverse magnetic mode was found to be greater than 50. The characteristic temperature measured from the plot of threshold current versus measurement temperature was between 130 and 150K.

Thrombin activates NF-kappa B through thrombin receptor and results in proliferation of vascular smooth muscle cells: role of thrombin in atherosclerosis and restenosis

We investigated the role of thrombin in the pathogenesis in atherosclerosis and restenosis. First we examined the effect of thrombin on cultured human vascular smooth muscle cells (VSMC). We showed that thrombin acts as a mitogen on VSMC through thrombin receptor. The expression of thrombin receptor was increased in the cell lines of VSMC established from directional coronary atherectomy (DCA). This is more pronounced in the cells from patients with restenosis after PTCA. Next we investigated the signaling pathway from thrombin/thrombin receptor. Thrombin activates thrombin receptor resulting in the exposing of the agonist peptide domain (thrombin receptor agonist peptide, TRAP). The signal from thrombin/thrombin receptor activated protein C kinase, tyrosine kinase, and MAP kinase and resulted in NF-kappa B activation. Furthermore, treatment of the cells with antisense p65 oligodeoxynucleotides of NF-kappa B inhibited the thrombin-stimulated growth of VSMC in vitro. These results suggest that thrombin may have a role in the pathogenesis of atherosclerosis and restenosis after PTCA through the thrombin receptor.

Utilization of biopsy-based genomic classifier to predict distant metastasis after definitive radiation and short-course ADT for intermediate and high-risk prostate cancer

BACKGROUND

We examined the ability of a biopsy-based 22-marker genomic classifier (GC) to predict for distant metastases after radiation and a median of 6 months of androgen deprivation therapy (ADT).

METHODS

We studied 100 patients with intermediate-risk (55%) and high-risk (45%) prostate cancer who received definitive radiation plus a median of 6 months of ADT (range 3-39 months) from 2001-2013 at a single center and had available biopsy tissue. Six to ten 4 micron sections of the needle biopsy core with the highest Gleason score and percentage of tumor involvement were macrodissected for RNA extraction. GC scores (range, 0.04-0.92) were determined. The primary end point of the study was time to distant metastasis. Median follow-up was 5.1 years. There were 18 metastases during the study period.

RESULTS

On univariable analysis (UVA), each 0.1 unit increase in GC score was significantly associated with time to distant metastasis (hazard ratio: 1.40 (1.10-1.84), P=0.006) and remained significant after adjusting for clinical variables on multivariable analysis (MVA) (adjusted hazard ratio: 1.36 (1.04-1.83), P=0.024). The c-index for 5-year distant metastasis was 0.45 (95% confidence interval: 0.27-0.64) for Cancer of the Prostate Risk Assessment score, 0.63 (0.40-0.78) for National Comprehensive Cancer Network (NCCN) risk groups, and 0.76 (0.57-0.89) for the GC score. Using pre-specified GC risk categories, the cumulative incidence of metastasis for GC>0.6 reached 20% at 5 years after radiation (P=0.02).

CONCLUSIONS

We believe this is the first demonstration of the ability of the biopsy-based GC score to predict for distant metastases after definitive radiation and ADT for intermediate- and high-risk prostate cancer. Patients with the highest GC risk (GC>0.6) had high rates of metastasis despite multi-modal therapy suggesting that they could potentially be candidates for treatment intensification and/or enrollment in clinical trials of novel therapy.

A putative plant homolog of the yeast beta-1,3-glucan synthase subunit FKS1 from cotton (Gossypium hirsutum L.) fibers

A novel plant gene CFL1 was cloned from cotton (Gossypium hirsutum L.) fibers by expressed sequence tag (EST) database searching and 5'-RACE (rapid amplification of cDNA ends). This gene shows sequence homology with FKS1 which has been identified as the putative catalytic subunit of the yeast beta-1,3-glucan synthase. It encodes a protein (CFL1p) of 219 kDa with 13 deduced transmembrane helices and 2 large hydrophilic domains, one of which is at the N-terminus and the other in the internal region of the polypeptide. CFL1 displays 21% identity and 41% similarity to FKS1 at the amino acid level over its entire length, with 31% identity and 52% similarity for the hydrophilic central domain. Using RNA and protein blot analysis, CFL1 was found to be expressed at higher levels in cotton fibers during primary wall development. CFL1 also had a strong expression in young roots. Using a calmodulin (CaM)-gel overlay assay, the hydrophilic N-terminal domain of CFL1p was shown to bind to CaM, while the hydrophilic central domain did not. A putative CaM-binding domain, 16 amino acids long, was predicted in the hydrophilic N-terminal domain. Moreover, a product-entrapment assay demonstrated that a protein associated with an in vitro-synthesized callose pellet could be labeled by anti-CFL1 antibodies. Our finding suggests that CFL1 is a putative plant homolog of the yeast beta-1,3-glucan synthase subunit FKS1 and could be involved in callose synthesis.

Human kinesin superfamily member 4 is dominantly localized in the nuclear matrix and is associated with chromosomes during mitosis

In a previous study, we identified the human counterpart of murine kinesin superfamily member 4 (KIF4), a microtubule-based motor protein [Oh, Hahn, Torrey, Shin, Choi, Lee, Morse and Kim (2000) Biochim. Biophys. Acta 1493, 219-224]. As an initial step to understand the function(s) of human KIF4, its subcellular localization in HeLa cells was examined by using immunocytochemical and subcellular fractionation methods, and it was found that most KIF4 is localized in the nucleus. Since murine KIF4 is known to transport cytoplasmic vesicles, dominant nuclear localization of the human counterpart was somewhat surprising. Subsequent subnuclear fractionation revealed predominant association of KIF4 with the nuclear matrix. These results clearly indicate that human KIF4 is, at least, a nuclear protein. In further confirmation of this conclusion, the hexapeptide PKLRRR (amino acids 773-778) in the molecule was found to function as a nuclear localization signal. During the mitotic phase of the cell cycle, human KIF4 was associated with the chromosomes, suggesting that human KIF4 might be a microtubule-based mitotic motor, with DNA as its cargo.

Review of Reservoir Parameters to Optimize SAGD and Fast-SAGD Operating Conditions

Abstract

Although high recovery efficiency is expected from the SAGD process, high steam production costs and the substantial volumes of water required have made us focus on more effective recovery methods. One such method is the Fast-SAGD process which utilizes one or more offset horizontal wells parallel to the original SAGD well pair.

In these studies, simulations were used to examine the reservoir parameters and operating conditions that need to be in place to optimize the SAGD process. Based on the simulation of a typical Cold Lake reservoir in Alberta, the studies found that relatively clean sand reservoirs with a minimum thickness of 20 m and a vertical permeability of 2.5 Darcy are good candidates for the application of SAGD. Also, reservoirs in a fining upward depositional environment are ideally suited for a SAGD operation.

The results of our studies also showed that, for the same operating conditions, Fast-SAGD improved energy efficiency by 24% and productivity by 35% over SAGD. Fast-SAGD is therefore a more efficient recovery process requiring less steam and having lower operating costs to produce the same amount of bitumen.

The case of two offset wells located on either side of one SAGD well pair promises the most effective Fast-SAGD configuration, even if a total of six offset wells with a SAGD well pair is still economic compared to the conventional SAGD process. Cumulative bitumen production is increased and at the same time the cumulative steam-oil ratio is decreased as a result of higher thermal efficiency.

Introduction

Alberta's oil sands contain the largest crude bitumen resource in the world, having approximately 259 billion cubic metres of initial oil in-place and 27.7 billion cubic metres of remaining established reserves (see Tables 1a and 1b)(1). Over 80% of these reserves can be produced only by using in situ recovery methods; therefore, research to find more effective in situ recovery methods is encouraged.

The SAGD process has been tested in the field, and is now in a commercial stage of production in Western Canadian oil sands(2). The application of SAGD in various reservoir conditions has been studied, and recently research studies that can not only reduce the steam production cost but also enhance heat efficiency of the SAGD process have been conducted(3).

In our studies, the characteristics of the SAGD recovery method were reviewed. In addition, the proper reservoir conditions and optimized operating conditions for the SAGD process were researched by conducting numerical simulation. The possibility of applying the Fast-SAGD process, a modification of the SAGD process(4), was also investigated in comparison to conventional SAGD. Finally, the operating conditions for the optimization of the Fast-SAGD process were studied.

Variations of SAGD Process

Enhancements

The conventional SAGD process is a steam injection recovery method which uses two horizontal wells. In the Peace River area, a small pressure differential between adjacent pattern steam chambers was applied to enhance the SAGD process(5). A steam drive process can be applied to the SAGD operation once sufficient bitumen mobility has been obtained between steam chambers.

Thrombin receptor mediated signals induce expressions of interleukin 6 and granulocyte colony stimulating factor via NF-kappa B activation in synovial fibroblasts

OBJECTIVE

To clarify the mechanism of thrombin receptor mediated signal transduction and the induction of cytokines by thrombin stimulation in rheumatoid synovial fibroblasts.

METHODS

Cytokines were measured by enzyme linked immunosorbent assay (ELISA) in the supernatants of cultured rheumatoid synovial fibroblasts stimulated by thrombin. To assess the mechanism of thrombin receptor mediated signal transduction in the rheumatoid synovial fibroblasts, electrophoretic mobility gel shift assay (EMSA), immunoglobulin kappa-chloramphenicol acetyltransferase (CAT) assay, and immunostaining for NF-kappa B subunit molecule was performed.

RESULTS

Thrombin stimulation activated the inducible transcription factor NF-kappa B, and then induced subsequent expressions of interleukin 6 (IL6) and granulocyte colony stimulating factor (G-CSF) in the cells.

CONCLUSION

Thrombin receptor mediated signal transduction could induce the expressions of IL6 and G-CSF, and increase inflammatory events in the cavum articulare via NF-kappa B activation.