bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sustained nitrite accumulation in a membrane‐assisted bioreactor (MBR) for the treatment of ammonium‐rich wastewater
Authors: Wyffels Stijn , Boeckx Pascal , Pynaert Kris , Verstraete Willy , Van Cleemput Oswald 
Published: March 2003

AbstractA membrane‐assisted bioreactor (MBR) for sustained nitrite accumulation is presented, treating a synthetic wastewater with total ammonium nitrogen (TAN) concentrations of 1 kg N m−3 at a hydraulic retention time down to 1 day. Complete biomass retention was obtained by microfiltration with submerged hollow fibre membranes. A membrane flux up to 189.5 dm3 day−1 m−2 could be maintained at a suction pressure below 100 kPa. Nitrification was effectively blocked at the nitrite stage (nitritation), and nitrate concentration was less than 29 g N m−3. The rate of aeration was reduced to obtain a mixture of ammonium and nitrite, and after adjusting this rate the TAN/NO2‐N ratio in the reactor effluent was kept around unity, making it suitable for further treatment by anaerobic oxidation of ammonium with nitrite. After increasing again the rate of aeration, complete nitrification to nitrate recovered after 11 days. It is suggested that nitrite accumulation resulted from a combination of factors. First, the dissolved oxygen (DO) concentration in the reactor was always limited with concentrations below 0.1 g DO m−3, thereby limiting nitrification and preventing significant nitrate formation. The latter is attributed to the fact that ammonium‐oxidising bacteria cope better with low DO concentrations than nitrite oxidisers. Second, the MBR was operated at a high ammonia concentration of 7–54 g N m−3, resulting in ammonia inhibition of the nitrite‐oxidising microorganisms. Third, a temperature of 35 °C was reported to yield a higher maximum growth rate for ammonium‐oxidising bacteria than for nitrite‐oxidising bacteria. Nitrite oxidisers were always present in the MBR but were out‐competed under the indicated process conditions, which is reflected in low concentrations of nitrate. Oxygen limitation was shown to be the most important factor to sustain nitrite accumulation. Nevertheless, nitritation was possible at ambient temperature (22–24 °C), lower ammonia concentration (<7 g N m−3) and when using raw nitrogenous wastewater containing some biodegradable carbon. Overall, application of the MBR for nitritation was shown to be a reliable technology.© 2003 Society of Chemical Industry
Mass transfer and hydrodynamic characteristics in a co‐current downflow contacting column
Authors: Dursun G , Orhan R , Akosman C 
Published: March 2003

AbstractHydrodynamic and mass transfer characteristics of water–air system in a co‐current downflow contacting column (CDCC) were studied for various nozzle diameters at different superficial gas velocities and liquid re‐circulation rates. Gas hold‐up and liquid‐side mass transfer coefficient increased with increasing superficial gas velocity and liquid flow rate but decreased with increasing nozzle diameter. It is shown that correlations developed, which are based on liquid kinetic power per liquid volume present in the column, and superficial gas velocity explains gas hold‐up and the mass transfer coefficient within an error 20% for all gas and liquid flow rates and nozzle diameters used. The constants of correlations for gas hold‐up and mass transfer coefficient were found to be considerably different from other gas–liquid contacting systems.© 2003 Society of Chemical Industry
Design and operation of unbaffled aerated agitated vessels with unsteadily forward–reverse rotating impellers handling viscous Newtonian liquids
Authors: Yoshida Masanori , Taguchi Yoji , Yamagiwa Kazuaki , Ohkawa Akira , Abe Masahiko , Tezura Shuichi , Shimazaki Masuo 
Published: March 2003

AbstractDesign and operation of unbaffled aerated agitated vessels with multiple unsteadily forward–reverse rotating impellers (AJITERs) for viscous Newtonian liquids were studied. The effects of operating conditions such as gas sparging rate, agitation rate and the number of impeller stages, geometrical conditions such as the diameters of vessel and impeller, and the physical properties of liquids on the drag and added moment of inertia coefficients, necessary to predict the average and maximum power consumptions of the impellers in AJITERs, were evaluated and the empirical relationships which estimate values of each of these coefficients are presented. The effects of operating conditions, geometrical conditions and liquid physical properties on the gas hold‐up, ϕgD, and volumetric oxygen transfer coefficient, kLaD, were evaluated in relation to the total power input which is the sum of the average power consumption of impellers, ie average agitation power input, and aeration power input. Empirical relationships, useful for design and operation of AJITERs, were obtained for each viscosity range, where the dependences of ϕgD and kLaD on the specific total power input and superficial gas velocity differed, to predict ϕgD and kLaD respectively as a function of the specific total power input, superficial gas velocity and liquid physical properties.© 2003 Society of Chemical Industry
Gene transfer into the liver by plasmid injection into the portal vein combined with electroporation
Authors: Kobayashi Shogo , Dono Keizo , Tanaka Toshiyuki , Takahara Shiro , Isaka Yoshitaka , Imai Enyu , Nagano Hiroaki , Tomoaki Kato , Umeshita Koji , Nakamori Shoji , Sakon Masato , Monden Morito 
Published: March 2003

AbstractBackgroundWe investigated the optimum conditions for gene transfer into the liver by injection of plasmid via the portal vein combined with electroporation.MethodsIn anesthetized 7‐week‐old male Shionogi Wistar rats, a tapered 3Fr. catheter was inserted through a branch of the colonic vein and its tip was secured into the portal vein. After clamping the vessels around the right and caudal lobes of the liver, FITC‐oligodeoxynucleotide (ODN), green fluorescence protein (GFP) plasmid, or pCAGGS‐luciferase was injected into the right and caudal lobes during electroporation using electric pulses applied to the caudal lobe only.ResultsTransfected cells were identified by FITC‐ODN and GFP fluorescence, and transfection efficacy was estimated by measurement of luciferase activity. FITC‐ODN and GFP were detected in the caudal lobes of the liver. FITC‐ODN was particularly present in hepatocytes surrounding the Glisson capsule and central veins, while GFP was detected in only hepatocytes surrounding the Glisson capsule. Luciferase activity in the liver was dependent on the plasmid concentration and voltage of the electric pulse, but independent of the volume of plasmid solution. Luciferase activity was limited in the right lobe, in which plasmid solution was injected but no electroporation was applied.ConclusionsOur results showed local expression of the induced gene at the electroporation site, suggesting it is potentially useful for liver function support during recovery after extensive liver surgery and for the treatment of chronic and/or diffuse liver diseases. Copyright © 2002 John Wiley & Sons, Ltd.
Vectors based on reducible polycations facilitate intracellular release of nucleic acids
Authors: Read Martin L. , Bremner K. Helen , Oupický David , Green Nicola K. , Searle Peter F. , Seymour Leonard W. 
Published: March 2003

AbstractBackgroundInefficient intracellular delivery of nucleic acids limits the therapeutic usefulness of synthetic vectors such as poly(L‐lysine) (PLL)/DNA polyplexes. This article reports on the characterisation of a new type of synthetic vector based on a linear reducible polycation (RPC) that can be cleaved by the intracellular environment to facilitate release of nucleic acids.MethodsRPCs of molecular weight (mwt) 45 and 187 kDa were prepared by oxidative polycondensation of the peptide Cys‐Lys10‐Cys and used to condense nucleic acids. The stability of RPC‐based polyplexes to reduction was determined using electrophoresis, dynamic light scattering and fluorescence techniques. Transfection activity was studied in several cancer cell lines (HeLa, LNCaP, PC‐3 and B16‐F10) using luciferase and green fluorescent protein (GFP) genes as reporter genes in the presence of chloroquine or the cationic lipid (N‐(1‐(2,3‐dioleoyloxy)propyl)‐N, N, N‐trimethylammonium chloride) (DOTAP). A CMV‐driven plasmid expressing the nitroreductase (ntr) gene was used to evaluate the therapeutic efficacy of RPC‐based delivery vectors.ResultsA 187‐fold higher level of gene expression indicated that intracellular delivery of DNA was more efficient using RPC/DOTAP compared with vectors based on non‐reducible PLL. Analysis by flow cytometry also showed enhanced delivery of the GFP gene by RPC/DOTAP in HeLa (51.5 ± 7.9%), LNCaP (55.2 ± 6.7%) and PC‐3 (66.1 ± 3.7%) cells. Transfection with the ntr gene and treatment with the prodrug CB1954 resulted in significant cell killing, achieving IC50 values similar to those previously attained with adenoviral vectors. Delivery of mRNA (20–75% of cells) was also more efficient using RPC/DOTAP than PLL/DOTAP (<5% of cells).ConclusionsThese results demonstrate that lipid‐mediated activation of RPC‐based polyplexes is a useful strategy to enhance intracellular delivery of nucleic acids and potentiate therapeutic activity. Copyright © 2002 John Wiley & Sons, Ltd.
Massive apoptotic cell death in chemically induced rat urinary bladder carcinomas following in situ HSVtk electrogene transfer
Authors: Shibata Masa‐Aki , Horiguchi Taisuke , Morimoto Junji , Otsuki Yoshinori 
Published: March 2003

AbstractBackgroundGene delivery in current gene therapy studies relies largely on recombinant viral vectors. However, the safety of this method is still under investigation. The effectiveness of in vivo electrogene transfer as a means of gene therapy for rat bladder cancers using the herpes simplex virus 1 thymidine kinase (HSVtk) gene in combination with ganciclovir (GCV) was therefore investigated.MethodsThe killing effects of HSVtk/GCV therapy were evaluated in transitional cell carcinoma (TCC) cells in vitro and in vivo. In animal experiments, electrogene transfer of HSVtk into N‐butyl‐N‐(4‐hydroxybutyl)nitrosamine (BBN)‐induced rat bladder tumors was conducted followed by GCV administration.ResultsIn vitro studies demonstrated that approximately 50–70% of the TCC cells died as a result of transfection with pHSVtk and GCV administration and that this treatment was associated with decreased DNA synthesis and elevated activities of caspase‐3, ‐8 and ‐9. A significantly decreased mitochondrial membrane potential was also noted in TCC cells given pHSV tk + GCV. A direct single injection of HSVtk into bladder tumors using in vivo electrogene transfer followed by GCV i.p. administration resulted in significant increases in the levels of apoptosis and histopathological necrosis accompanied by marked inflammation. Active caspase‐3 was strongly expressed in the cell death areas of the TCC in rats given pHSVtk/GCV therapy.ConclusionsIn vivo electrogene transfer results in efficient gene transfer in BBN‐induced rat bladder tumors and the HSVtk/GCV prodrug system induces significant cell death which appears to be, at least, mediated via the mitochondrial apoptotic pathway. Copyright © 2002 John Wiley & Sons, Ltd.
Inhibition of HIV‐1 replication in primary human T cells transduced with an intracellular anti‐HIV‐1 p17 antibody gene
Authors: Tewari Deepanker , Notkins Abner Louis , Zhou Paul 
Published: March 2003

AbstractBackgroundPreviously we reported that human CD4+ T cell lines stably expressing anti‐HIV‐1 gag p17 scFv/Cκ in the cytosol or nucleus were resistant to HIV‐1 challenge. Inhibition of HIV‐1 by anti‐HIV‐1 gag p17 scFv/Cκ occurred at both the pre‐ and post‐integration steps of the viral cycle. To simulate more closely the in vivo infection process, in this study we tested anti‐HIV‐1 activity of anti‐HIV‐1 gag p17 scFv/Cκ in primary human T cells.MethodsAnti‐HIV‐1 gag p17 scFv/Cκ gene that is targeted into cytoplasm was inserted into a MMLV vector and transfected into packaging cell line PT67. The recombinant virus was used to transduce primary human T cells and human CD4+ T cell line Jurkat. Following transduction, transduction efficiency, transgene expression, and cell phenotypes were studied. Transduced cells were then challenged with 100 TCID50 of HIV‐1 IIIB and primary isolate 5AO12. Following challenge, HIV‐1 replication was monitored by p24 production.ResultsBoth transduced Jurkat and primary human T cells expressed the transgene. The expression of the transgene did not alter cell growth and CD4 or CD8 expression. However, HIV‐1 replication in scFv/Cκ‐transduced Jurkat cells was inhibited by nearly 90% as compared with vector controls. More importantly, HIV‐1 replication in primary human T cells from multiple donors transduced with the anti‐HIV‐1 gag p17 scFv/Cκ gene was inhibited by as much as 99% as compared with primary T cells transduced with the vector control. The inhibition of replication was not due to interference in viral entry or reverse transcription. The less that HIV‐1 replicated in different donor cells, the higher the degree of protection.ConclusionsThe expression of the anti‐HIV‐1 gag p17 scFv/Cκ gene construct in primary human T cells renders these cells resistant to HIV‐1 and points to the potential clinical usefulness of this gene construct for anti‐HIV‐1 gene therapy. Copyright © 2002 John Wiley & Sons, Ltd.
In vivo expansion of transduced murine hematopoietic cells with a selective amplifier gene
Authors: Kume Akihiro , Koremoto Masahide , Xu Ruifang , Okada Takashi , Mizukami Hiroaki , Hanazono Yutaka , Hasegawa Mamoru , Ozawa Keiya 
Published: March 2003

AbstractBackgroundHematopoietic stem‐cell‐directed gene transfer has achieved limited success in transducing clinically relevant levels of target cells. The expansion of gene‐modified cells is one way to circumvent the problem of inefficient transduction with current vectors. To this end, we have developed ‘selective amplifier genes’ (SAGs) that encode chimeric proteins that are a fusion of granulocyte colony‐stimulating factor receptor and the steroid‐binding domain. Prototype SAGs conferred estrogen‐responsive growth on murine hematopoietic progenitors.MethodsWe constructed a retroviral vector coexpressing an SAG for 4‐hydroxytamoxifen (Tm)‐specific proliferation and the enhanced green fluorescent protein (EGFP). Murine bone marrow cells were transduced with this vector and transplanted into myeloablated mice. Subsequently, recipients were challenged with Tm, and EGFP+ cells were enumerated.ResultsThe challenge induced a significant increase in EGFP+ leukocytes (21 ± 4% to 27 ± 5%), while EGFP+ cells decreased in untreated animals (21 ± 5% to 10 ± 3%). Three months later, bone marrow cells were transplanted from the unchallenged mice to secondary hosts. Again the administration of Tm resulted in an increase of EGFP+ cells (16 ± 4% to 35 ± 3%), contrasting to a decrease in controls (22 ± 4% to 12 ± 4%), and the difference was significant for more than 3 months. A detailed study of lineage showed a preferential expansion of EGFP+ cells in granulocytes and monocytes following Tm administration.ConclusionsLong‐term repopulating cells were transduced with the SAG, and the transduced granulocyte/monocyte precursors were most likely to be expandable in vivo upon Tm stimulation. Copyright © 2002 John Wiley & Sons, Ltd.
Optimization of human erythropoietin secretion from MLV‐infected human primary fibroblasts used for encapsulated cell therapy
Authors: Schwenter F. , Déglon N. , Aebischer P. 
Published: March 2003

AbstractBackgroundThe transplantation of encapsulated cells genetically engineered to secrete human erythropoietin (hEpo) represents an alternative to repeated injections of the recombinant hormone for the treatment of Epo‐responsive anemia. In the present study, the ability of primary human foreskin fibroblasts to secrete high levels of hEpo and the importance of cis‐acting elements and infection conditions on transgene expression level were assessed.MethodsThe transduction efficiency was first evaluated with β‐galactosidase (LacZ)‐encoding retroviral vectors derived from the murine leukemia retrovirus (MLV) pseudotyped either with an amphotropic envelope or with the G glycoprotein of vesicular stomatitis virus (VSV‐G). Human fibroblasts were then infected with an amphotropic hEpo‐expressing retroviral vector, which was modified by insertion of a post‐transcriptional regulatory element from the woodchuck hepatitis virus (WPRE) and a Kozak consensus sequence (KZ). Human Epo production was further optimized by increasing the multiplicity of infection and by selecting high producer cells. The survival and the transgene expression of these fibroblasts were finally evaluated in vivo. The cells were encapsulated into microporous hollow fibers and subcutaneously implanted in nude mice.ResultsA secretion level of approximately 5 IU hEpo/106 cells/day was obtained with the basal vector. A 7.5‐fold increase in transgene expression was observed with the insertion of WPRE and KZ elements. Finally, according to the optimization of infection conditions, we obtained a 40‐fold increase in hEpo secretion, reaching approximately 200 IU hEpo/106 cells/day. The in vivo experiments showed an increase in the hematocrit during the first 2 weeks and elevated levels exceeding 60% were maintained over a 6‐week period.ConclusionsThese results indicate that primary human fibroblasts represent a promising source for encapsulated cell therapy. Copyright © 2003 John Wiley & Sons, Ltd.
The in vivo use of chloroquine to promote non‐viral gene delivery to the liver via the portal vein and bile duct
Authors: Zhang Xiaohong , Sawyer Greta J. , Dong Xuebin , Qiu Ying , Collins Louise , Fabre John W. 
Published: March 2003

AbstractBackgroundAssistance with exit from endocytic vesicles is a key factor for non‐viral gene delivery, and is a particular challenge in vivo. We have evaluated the in vivo use of chloroquine administered systemically, orally and/or locally for gene delivery to the liver.MethodsThe DNA vector (polylysine‐molossin) is a 31 amino acid bifunctional synthetic peptide, incorporating an amino terminal chain of 16 lysines for electrostatic binding of DNA. Gene delivery was to the right lateral lobes of the liver by branches of the bile duct or portal vein.ResultsSingle intraperitoneal injections of 8, 25 and 75 mg/kg of chloroquine (the maximum tolerated single intraperitoneal dose) resulted in increasing levels of luciferase reporter gene expression, following gene delivery via the bile duct. 100 mg/kg of chloroquine orally was equivalent to 25 mg intraperitoneally. A 3‐day course of intraperitoneal and oral chloroquine gave ∼10–30‐fold higher gene expression than an optimal single dose, and resulted in a scattering of positive hepatocytes in the lobule. Gene delivery via the bile duct was much more effective than via the portal vein. Serum chloroquine levels at the time of gene delivery showed a highly significant correlation with gene expression, but the maximum achievable levels in vivo (∼1–2 µM) were much lower than those required for optimal in vitro gene delivery. Chloroquine (0.2–5 mM) was also given locally in the bile duct with vector/DNA complexes. Maximum gene expression was obtained with 0.5 mM local chloroquine, but the level of gene expression was only equivalent to the 25 mg intraperitoneal dose.ConclusionsThe in vivo use of chloroquine is effective for promoting gene delivery to the liver, but requires multiple dosing and is limited by systemic toxicity. Copyright © 2002 John Wiley & Sons, Ltd.
Determination of polychlorinated dibenzo‐p‐dioxins, dibenzofurans, and biphenyls by gas chromatography/mass spectrometry in the negative chemical ionization mode with different reagent gases
Authors: Chernetsova Elena S. , Revelsky Alexander I. , Revelsky Igor A. , Mikhasenko Ilya A. , Sobolevsky Tim G. 
Published: March 2003

Abstract

I.
Introduction
374

II.
Approaches to Selective and Sensitive GC/MS Determination of PCDD, PCDF, and PCB
374

A. Most Prevalent Ionization Modes in GC/MS
374

B. Sensitive Detection: Negative Chemical Ionization with Different Reagent Gases
375

1. Determination of Polychlorinated Dibenzo‐p‐dioxins (PCDDs) and Dibenzofurans (PCDFs) with Different
Reagent Gases
376

a. CH4 as reagent gas
376

b. O2 as reagent gas
377

c. O2 as reagent gas [atmospheric pressure chemical ionization (APCI)]
378

d. CH4/O2 as reagent gas
379

e. CH4/N2O as reagent gas
380

f. i‐C4H10/CH2Cl2/O2 as reagent gas
380

g. Ar/CH4, CH4, i‐C4H10 as reagent gases
381

h. H2 as reagent gas
381

i. Ar, Xe, SF6, H2, and He as reagent gases
381

2. Determination of Polychlorinated Biphenyls (PCBs) with Different Reagent Gases
382

a. CH4 and CH4/O2 as reagent gases
382

b. O2 as reagent gas [atmospheric pressure chemical ionization (APCI)]
382

c. CH4 and NH3 as reagent gases
383

d. CH4/O2, Ar/O2, CH4/H2O, and CH4 as reagent gases
383

III.
Conclusion and Actual Problems
383

References
385

Reagent gases that are used in mass spectrometry in the NCI mode for the determination of polychlorinated dibenzo‐p‐dioxins (PCDDs), dibenzofurans (PCDFs), and biphenyls (PCBs) are discussed. Ion‐molecule reactions and respective characteristic ions that form while using reagent gases (CH4, O2, i‐C4H10, NH3, H2, He, Ar, Xe, SF6) or gas mixtures (CH4/O2, Ar/CH4, CH4/H2O, Ar/O2, i‐C4H10/CH2Cl2/O2) are reviewed. It is shown that only CH4, O2, CH4/O2, and CH4/N2O are widely used and well studied, even though—in the case of these reagent gases—there are contradictions between the publications of various authors. Such reagent gases as NH3 and He are not well studied, but further investigations of their use for the determination of organochlorine pollutants could be of interest. The possibilities of more sensitive and selective determination of PCDDs, PCDFs, and PCBs are discussed. © 2003 Wiley Periodicals, Inc., Mass Spec Rev 21:373–387, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mas.10037