bluuebunny/crossref_metadata_2025_split huggingface dataset:
How I treat Philadelphia chromosome–positive acute lymphoblastic leukemia
Authors: Fielding Adele K. 
Published: July 2010

AbstractThe Philadelphia chromosome is present in approximately 20% to 30% of adults with acute lymphoblastic leukemia (ALL). The poor prognosis of this relatively uncommon acute leukemia has led to the rapid adoption of treatment strategies such as unrelated donor hematopoietic stem cell transplant and tyrosine kinase inhibitors into clinical practice, despite a relative paucity of randomized clinical trials. Recently, there has been a surge of interest in the underlying biology of ALL. In combination with an accumulation of more mature clinical study data in Philadelphia-positive ALL, it is increasingly possible to make more rational and informed treatment choices for patients of all ages. In this article, I review available data and indicate how I personally interpret current evidence to make pragmatic treatment choices with my patients, outside of clinical trials. My strongest recommendation is that all physicians who are treating this rare disease actively seek appropriate clinical trials for their patients wherever possible.
Th1-driven immune reconstitution disease in Mycobacterium avium–infected mice
Authors: Barber Daniel L. , Mayer-Barber Katrin D. , Antonelli Lis R. V. , Wilson Mark S. , White Sandra , Caspar Patricia , Hieny Sara , Sereti Irini , Sher Alan 
Published: July 2010

AbstractFollowing antiretroviral therapy, a significant proportion of HIV+ patients with mycobacterial coinfections develop a paradoxical, poorly understood inflammatory disease termed immune reconstitution inflammatory syndrome (IRIS). Here, we show that Mycobacterium avium–infected T cell–deficient mice injected with CD4 T cells also develop an immune reconstitution disease (IRD) manifesting as weight loss, impaired lung function, and rapid mortality. This form of IRD requires Ag recognition and interferonγ production by the donor CD4 T cells and correlates with marked alterations in blood and tissue CD11b+ myeloid cells. Interestingly, disease is associated with impaired, rather than augmented, T-cell expansion and function and is not strictly dependent on lymphopenia-induced T-cell proliferation. Instead, our findings suggest that mycobacterial-associated IRIS results from a heightened sensitivity of infected lymphopenic hosts to the detrimental effects of Ag-driven CD4 T-cell responses.
Cinnamon extract induces tumor cell death through inhibition of NFκB and AP1
Authors: Kwon Ho-Keun , Hwang Ji-Sun , So Jae-Seon , Lee Choong-Gu , Sahoo Anupama , Ryu Jae-Ha , Jeon Won Kyung , Ko Byoung Seob , Im Chang-Rok , Lee Sung Haeng , Park Zee Yong , Im Sin-Hyeog 
Published: July 2010

Abstract

Background

Cinnamomum cassia bark is the outer skin of an evergreen tall tree belonging to the family Lauraceae containing several active components such as essential oils (cinnamic aldehyde and cinnamyl aldehyde), tannin, mucus and carbohydrate. They have various biological functions including anti-oxidant, anti-microbial, anti-inflammation, anti-diabetic and anti-tumor activity. Previously, we have reported that anti-cancer effect of cinnamon extracts is associated with modulation of angiogenesis and effector function of CD8+ T cells. In this study, we further identified that anti-tumor effect of cinnamon extracts is also link with enhanced pro-apoptotic activity by inhibiting the activities NFκB and AP1 in mouse melanoma model.

Methods
Water soluble cinnamon extract was obtained and quality of cinnamon extract was evaluated by HPLC (High Performance Liquid Chromatography) analysis. In this study, we tested anti-tumor activity and elucidated action mechanism of cinnamon extract using various types of tumor cell lines including lymphoma, melanoma, cervix cancer and colorectal cancer in vitro and in vivo mouse melanoma model.

Results
Cinnamon extract strongly inhibited tumor cell proliferation in vitro and induced active cell death of tumor cells by up-regulating pro-apoptotic molecules while inhibiting NFκB and AP1 activity and their target genes such as Bcl-2, BcL-xL and survivin. Oral administration of cinnamon extract in melanoma transplantation model significantly inhibited tumor growth with the same mechanism of action observed in vitro.

Conclusion
Our study suggests that anti-tumor effect of cinnamon extracts is directly linked with enhanced pro-apoptotic activity and inhibition of NFκB and AP1 activities and their target genes in vitro and in vivo mouse melanoma model. Hence, further elucidation of active components of cinnamon extract could lead to development of potent anti-tumor agent or complementary and alternative medicine for the treatment of diverse cancers.
ChemInform Abstract: Structural and Electrochemical Study od a New Crystalline Hydrate Iron(III) Phosphate FePO4·H2O Obtained from LiFePO4(OH) by Ion Exchange.
Authors: Marx Nicolas , Croguennec Laurence , Carlier Dany , Bourgeois Lydie , Kubiak Pierre , Le Cras Frederic , Delmas Claude 
Published: July 2010

AbstractFePO4·H2O is prepared by Li+/H+ exchange from an aqueous HNO3 suspension of LiFePO4(OH) at about 60 °C.
ChemInform Abstract: Persistent UV Phosphors for Application in Photo Catalysis.
Authors: Gutierrez‐Martin F. , Fernandez‐Martinez F. , Diaz P. , Colon C. , Alonso‐Medina A. 
Published: July 2010

AbstractCe3+‐doped strontium aluminosilicates (Sr1‐νMν) 1+yAl2‐xBxSiyO4+3y (M: Ca, Mg, Ba) are prepared by solid state reactions of Al2O3, B2O5, SiO2, MCO3 (M: Ca, Mg, Ba), and Ce2(CO3)3 (5% H2/95% N2, 1200 °C, 2 h) and characterized by XRD and photoluminescence spectroscopy.
ChemInform Abstract: Synthesis and Lithium Fast‐Ion Conductivity of a New Complex Hydride Li3(NH2)2I with Double‐Layered Structure.
Authors: Matsuo Motoaki , Sato Toyoto , Miura Yohei , Oguchi Hiroyuki , Zhou Yu , Maekawa Hideki , Takamura Hitoshi , Orimo Shin‐ichi 
Published: July 2010

AbstractThe title compound is prepared by milling of a mixture of (1‐x)LiNH2 and xLiI (x = 0.06—0.75) for 5 h under Ar followed by heating at 423 K for 12 h.
ChemInform Abstract: Observation and Isolation of Layered and Framework Ytterbium Hydroxide Phases Using in situ Energy‐Dispersive X‐Ray Diffraction.
Authors: McIntyre Laura J. , Prior Timothy J. , Fogg Andrew M. 
Published: July 2010

AbstractThe hydrothermal synthesis of the compounds Ln2(OH)5NO3·xH2O (Ln: Y, Er, Yb) from aqueous solutions of Ln(NO3)3, NaOH, and NaNO3 (autoclave, 100—220 °C) is monitored by time‐resolved, in situ energy‐dispersive XRD.
ChemInform Abstract: Achiral Additives Dramatically Enhance Enantioselectivities in the BINOL—Ti(IV) Complex Catalyzed Aldol Condensations of Aldehydes with Chan′s Diene.
Authors: Xu Qinyao , Yu Jianghui , Han Fengyan , Hu Juan , Chen Weiping , Yang Liping 
Published: July 2010

AbstractAddition of LiCl to Ti(O‐iPr)4 and (S)‐BINOL provides an efficient catalyst system which allows highly enantioselective coupling of various aldehydes with Chan′s diene (I).
ChemInform Abstract: Rational Tuning of the Rigidity of a Ligand Scaffold: Synthesis of Diphenylsulfide‐Linked Bis(oxazoline) Ligands and Their Application in Asymmetric Allylic Alkylation.
Authors: Du Xian , Liu Han , Du Da‐Ming 
Published: July 2010

AbstractIt is found that the oxazolines (I) efficiently promote the enantioselective allylic alkylation.
ChemInform Abstract: Transition‐Metal‐Free Electrophilic Amination Between Aryl Grignard Reagents and N‐Chloroamines.
Authors: Hatakeyama Takuji , Yoshimoto Yuya , Ghorai Sujit K. , Nakamura Masaharu 
Published: July 2010

AbstractVarious functional groups are tolerated under the mild conditions.
ChemInform Abstract: Copper(I)‐Catalyzed Addition of Grignard Reagents to in situ‐Derived N‐Sulfonyl Azoalkenes: An Umpolung Alkylation Procedure Applicable to the Formation of Up to Three Contiguous Quaternary Centers.
Authors: Hatcher John M. , Coltart Don M. 
Published: July 2010

AbstractThe first Cu(I)‐catalyzed addition of Grignard reagents to in situ‐derived N‐sulfonyl azoalkenes is described.
ChemInform Abstract: Air‐Stable Titanocene Bis(perfluorooctanesulfonate) as a New Catalyst for Acylation of Alcohols, Phenols, Thiols, and Amines under Solvent‐Free Conditions.
Authors: Qiu Renhua , Zhang Guoping , Ren Xiaofang , Xu Xinhua , Yang Ronghua , Luo Shenglian , Yin Shuangfeng 
Published: July 2010

AbstractAcyl protection of a wide range of primary, secondary and tertiary aliphatic and aromatic alcohols is efficiently achieved using titanocene bis(perfluorooctanesulfonate) as catalyst under solvent‐free conditions.
ChemInform Abstract: A Rapid and Convergent Synthesis of α,α‐Difluoro‐β‐hydroxyketones Through Regiospecific Defluorinative Alkylation Reaction.
Authors: Yanai Hikaru , Ichikawa Tatsunori , Taguchi Takeo 
Published: July 2010

AbstractIt is discovered that (‐)‐sparteine accelerates both the defluorinative alkylation of trifluoroacetaldehyde N,O‐acetals with alkyllithiums and the following Reformatyky‐type C—C‐bond formation with aldehydes and ketones.
ChemInform Abstract: Regioselective Copper‐Catalyzed Alkylation of [2.2.2]‐Acylnitroso Cycloadducts: Remarkable Effect of the Halide of Grignard Reagents.
Authors: Crotti Stefano , Bertolini Ferruccio , di Bussolo Valeria , Pineschi Mauro 
Published: July 2010

AbstractThe choice of the reaction conditions and the nature of the halide for the Grignard reagents is crucial for the formation of the products of the type (III) or (IV).
ChemInform Abstract: Direct Asymmetric Aldol Reaction with Recyclable Fluorous Organocatalyst.
Authors: Miura Tsuyoshi , Imai Kie , Ina Mariko , Tada Norihiro , Imai Nobuyuki , Itoh Akichika 
Published: July 2010

AbstractThe new fluorous sulfonamide PFSA promotes effectively the aldol reaction at room temperature and in a shorter time compared to the diamine precursor.
ChemInform Abstract: Asymmetric Addition of Trimethylsilylcyanide to N‐Benzylimines Catalyzed by Recyclable Chiral Dimeric V(V) Salen Complex.
Authors: Khan Noor‐ul H. , Saravanan S. , Kureshy Rukhsana I. , Abdi Sayed H. R. , Sadhukhan Arghya , Bajaj Hari C. 
Published: July 2010

AbstractA chiral dimeric vanadium(V)—salen complex smoothly catalyzes the asymmetric Strecker reaction of a variety of N‐benzylimines with TmsCN.
ChemInform Abstract: Tunable Bromomagnesium Thiolate Tishchenko Reaction Catalysts: Intermolecular Aldehyde—Trifluoromethylketone Coupling.
Authors: Cronin Linda , Manoni Francesco , O'Connor Cornelius J. , Connon Stephen J. 
Published: July 2010

AbstractThe thiolate generated from PhMgBr and BnSH is found to be an efficient catalyst for the Tishchenko reaction.
ChemInform Abstract: Rongalite® and Base‐Promoted Cleavage of Disulfides and Subsequent Michael Addition to α,β‐Unsaturated Ketones/Esters: An Odorless Synthesis of β‐Sulfido Carbonyl Compounds.
Authors: Guo Wenxue , Lv Guangshu , Chen Jiuxi , Gao Wenxia , Ding Jinchang , Wu Huayue 
Published: July 2010

AbstractA rapid, convenient, and widely applicable method to prepare synthetically important β‐sulfido carbonyl compounds is reported.
ChemInform Abstract: Rearrangement—Cyclization of Dialkyl(4‐hydroxybut‐2‐ynyl)methallyl‐ and Dialkylcrotyl(4‐hydroxy‐but‐2‐ynyl) Ammonium Halides.
Authors: Chukhajian E. O. , Gabrielyan A. S. , Chukhajian El. O. , Shahkhatuni K. G. , Panosyan H. A. 
Published: July 2010

AbstractThe title compounds (I) and (III) undergo a Stevens rearrangement under the influence of aqueous alkali with transfer of the reaction center in the receiving group and inversion of the migrating group.
ChemInform Abstract: Unexpected Course for the Reaction of 1‐Di(ethoxycarbonyl) methyl‐1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridinium Bromide with Dimethyl Acetylenedicarboxylate in the Presence of Triethylamine.
Authors: Soldatova S. A. , Soldatenkov A. T. , Suleimanov R. R. , Kolyadina N. M. , Khrustalev V. N. 
Published: July 2010

AbstractThe substituted pyrrolidine (III) is obtained instead of an expected azonine derivative.
ChemInform Abstract: Gold(I)‐Catalyzed Tandem Cyclization Approach to Tetracyclic Indolines.
Authors: Liu Yongxiang , Xu Wenqing , Wang Xiang 
Published: July 2010

AbstractThe highly stereoselective reaction of alkynylindoles allows the construction of 2 rings and 2 stereocenters including a quaternary carbon center in one step with a wide substrate scope.
ChemInform Abstract: Design and Synthesis of Novel 3,4‐Disubstituted Pyrazoles for Nanomedicine Applications Against Malignant Gliomas.
Authors: Franchini Mauro Comes , Bonini Bianca Flavia , Camaggi Carlo Maurizio , Gentili Denis , Pession Annalisa , Rani Monica , Strocchi Elena 
Published: July 2010

AbstractA series of 4‐acylamino‐3‐aryl substituted pyrazoles is synthesized and evaluated in vitro for their cytotoxicity against U87MG glioma cells.
ChemInform Abstract: A New Strategy for the Synthesis of Benzoxanthenes Catalyzed by Proline Triflate in Water.
Authors: Li Jianjun , Lu Lingmei , Su Weike 
Published: July 2010

AbstractOne‐pot three‐component condensation of α‐ or β‐naphthol with 1,3‐dicarbonyl compounds and aromatic aldehydes affords a variety of biologically interesting benzo[c]xanthene derivatives.
ChemInform Abstract: Dichloro‐4‐quinolinol‐3‐carboxylic Acid: Synthesis and Antioxidant Abilities to Scavenge Radicals and to Protect Methyl Linoleate and DNA.
Authors: Li Guo‐Xiang , Liu Zai‐Qun , Luo Xu‐Yang 
Published: July 2010

AbstractFollowing the Gould—Jacobs reaction, a series of 4‐quinolinol‐3‐carboxylic acids (III) is prepared and investigated for their antioxidant properties in chemical and biological experiments.
ChemInform Abstract: Discovering Some Novel Tetrahydroquinoline Derivatives Bearing the Biologically Active Sulfonamide Moiety as a New Class of Antitumor Agents.
Authors: Alqasoumi Saleh I. , Al‐Taweel Areej M. , Alafeefy Ahmed M. , Ghorab Mostafa M. , Noaman Eman 
Published: July 2010

AbstractAll newly synthesized compounds (V) are evaluated for their in vitro antitumor activity.
ChemInform Abstract: Regioselective Synthesis and Structure of New Spiro‐Isoquinolinedione Derivatives.
Authors: Jegham Nafaa , Kacem Yakdhane , Ben Hassine Bechir 
Published: July 2010

AbstractThe 1,3‐dipolar cycloaddition reaction of diones (I) with in situ generated arylnitrile oxides leads to separable mixtures of regioisomers (III) and (IV).
ChemInform Abstract: Synthesis of Some New Hetarylpyranopyridazines, Cinnolines, and Hetarylpyridazine Derivatives.
Authors: Abdel‐Megid M. , Gabr Y. , Awas M. A. A. , Abdel‐Fatah N. M. 
Published: July 2010

AbstractThe combination of pyridazine with γ‐pyrone in a molecular frame‐work via different methods starting from 4‐acetylpyridazinone (I) is presented.
ChemInform Abstract: Fe Nanoparticle Mediated C—N Bond‐Forming Reaction: Regioselective Synthesis of 3‐[(2‐Chloroquinolin‐3‐yl)methyl]pyrimidin‐4(3H)ones.
Authors: Roopan Selvaraj Mohana , Khan Fazlur Rahman Nawaz , Mandal Badal Kumar 
Published: July 2010

AbstractInterestingly, the scope of the method can be expanded to the alkylation with benzyl chloride.
ChemInform Abstract: Synthesis of 8‐(Cyclopentyloxy)phenyl Substituted Xanthine Derivatives as Adenosine A2A Ligands.
Authors: Bansal Ranju , Kumar Gulshan , Gandhi Deepika , Yadav Rakesh , Younng Louise C. , Harvey Alan L. 
Published: July 2010

AbstractA variety of new vanilloid‐based xanthine derivatives (IV) is synthesized and evaluated for the affinity for adenosine receptors.
ChemInform Abstract: Synthesis and Antimycobacterial Activity of Azetidine‐, Quinazoline‐ and Triazolo‐thiadiazole‐Containing Pyrazines.
Authors: Bonde Chandrakant G. , Peepiwal Ashok , Gaikwad Naresh J. 
Published: July 2010

AbstractThe new pyrazine derivatives (Vb), (Vc) and (VIIIc) and (VIIIe) show good antimycobacterial activities.
ChemInform Abstract: A Regio‐ and Diastereoselective Transformation of 3‐Dienyl‐2‐azetidinones to Novel Pyrroloxazine.
Authors: Anand Amit , Bhargava Gaurav , Kumar Vipan , Mahajan Mohinder P. 
Published: July 2010

AbstractThe three‐step sequence involves regioselective nitro‐Diels—Alder cycloaddition of lactams (I) with nitrosobenzene, cleavage of the lactam ring and intramolecular iodocyclization.
ChemInform Abstract: Palladium(II)‐Catalyzed 5‐endo Epoxynitrile Cyclizations: Total Syntheses of Enokipodins A (V) and B (VI).
Authors: Lujan‐Montelongo Jesus Armando , Avila‐Zarraga Jose G. 
Published: July 2010

AbstractThe approach is based on the cation‐controlled regioselective ring‐opening of a tertiary epoxynitrile and a following non‐favored Pd‐catalyzed 5‐endo cyclization.
ChemInform Abstract: Antitrypanosomal Pyridoacridine Alkaloids from the Australian Ascidian Polysyncraton echinatum.
Authors: Feng Yunjiang , Davis Rohan A. , Sykes Melissa L. , Avery Vicky M. , Carroll Anthony R. , Camp David , Quinn Ronald J. 
Published: July 2010

AbstractA novel pyridoacridine alkaloid 12‐deoxyascididemin (I) is isolated together with the known ascididemin (II) and eilatin and their biological evaluation shows potent antitrypanosomal activity.
ChemInform Abstract: Securinega Alkaloids from Flueggea leucopyra.
Authors: Wang Guo‐cai , Wang Ying , Zhang Xiao‐qi , Li Yao‐lan , Yao Xin‐sheng , Ye Wen‐cai 
Published: July 2010

AbstractSecurinine, the major alkaloid from Securinega suffruticosa, is a stereospecific GABA (A) receptor antagonist with significant CNS activity.
ChemInform Abstract: Chromene and Prenylated Xanthones from the Roots of Cratoxylum formosum ssp. pruniflorum.
Authors: Boonnak Nawong , Karalai Chatchanok , Chantrapromma Suchada , Ponglimanont Chanita , Kanjana‐Opas Akkharawit , Chantrapromma Kan , Kato Shigeru 
Published: July 2010

AbstractThe two new xanthones, pruniflorone K (I) and L (II), don′t exhibit antimicrobal activities.
ChemInform Abstract: A Hepatitis B Virus Inhibitory Neolignan from Herpetospermum caudigerum.
Authors: Yang Fan , Zhang Hong‐Jun , Zhang Yuan‐Yuan , Chen Wan‐Sheng , Yuan Hai‐Long , Lin Hou‐Wen 
Published: July 2010

AbstractThe seeds of Herpetospermum caudigerum are used in the traditional Tibetan medicine for the treatment of liver diseases.
ChemInform Abstract: Cannabimovone, a Cannabinoid with a Rearranged Terpenoid Skeleton from Hemp.
Authors: Taglialatela‐Scafati Orazio , Pagani Alberto , Scala Fernando , De Petrocellis Luciano , Di Marzo Vincenzo , Grassi Gianpaolo , Appendino Giovanni 
Published: July 2010

AbstractThe absolute configuration of title compound (I) is tentatively assigned in analogy to that of cannabidiol.
Stability, preservation, and quantification of hormones and estrogenic and androgenic activities in surface water runoff
Authors: Havens Sonya M. , Hedman Curtis J. , Hemming Jocelyn D.C. , Mieritz Mark G. , Shafer Martin M. , Schauer James J. 
Published: July 2010

Abstract
Degradation of hormones that may occur during storage of surface water samples can lead to underestimations in estrogenic and androgenic activities and inaccuracies in hormone concentrations. The current study investigated the use of sodium azide, hydrochloric acid (HCl), and sulfuric acid (H2SO4) to inhibit the degradation of hormones and estrogenic and androgenic activities in samples of surface water runoff from cattle manure–amended fields during storage at 4°C. Hormones and hormone metabolites were extracted using solid-phase extraction and analyzed using high-performance liquid chromatography (HPLC) with tandem MS. Estrogenic and androgenic activities were assessed by E-screen and A-screen, respectively. Results of the current study indicate significant degradation of estrogenic, androgenic, and progestogenic hormones and activities, which is likely attributable to microbial activity, within hours of sample collection. The inclusion of internal standards provides a means to account for hormone losses caused by extraction inefficiency and to some extent degradation. However, internal standards are unable to adequately account for significant losses and are not available for E-screen and A-screen. Sodium azide did not adequately inhibit androgen degradation at the concentration used (1 g/L). Acid preservation (HCl or H2SO4, pH 2) stabilized the estrogenic and androgenic activities, and coupling acid preservation with the use of internal standards resulted in reliable and accurate recovery of a suite of androgens, estrogens, and progestogens for up to 14 d of storage at 4°C. Environ. Toxicol. Chem. 2010;29:2481–2490. © 2010 SETAC
Partitioning of tetra- and pentabromo diphenyl ether and benzo[a]pyrene among water and dissolved and particulate organic carbon along a salinity gradient in coastal waters
Authors: Kuivikko Miika , Sorsa Karoliina , Kukkonen Jussi V.K. , Akkanen Jarkko , Kotiaho Tapio , Vähätalo Anssi V. 
Published: July 2010

Abstract
This study assessed the partitioning of 2,2′,4,4′-tetrabromo diphenyl ether (BDE-47), 2,2′,4,4′,5-pentabromo diphenyl ether (BDE-99) and benzo[a]pyrene (BaP) among water, dissolved organic carbon (DOC: 4.93–8.72 mg/L), and particulate organic carbon (POC: 191–462 µg/L) along the salinity gradient (0–5.5‰) of the Baltic Sea off the coast of Finland. Equilibrium dialysis and two solid-phase extraction techniques using polyoxymethylene polymer (POM) were used to determine partitioning coefficients. Experiments using artificial coastal water (ACW) with Nordic fulvic (FAs) and humic acids (HAs) were used to assess the effect of salinity (0 and 5.5‰) on the DOC–water partitioning of the model compounds. All three compounds bound more (2.2–3.8-fold) to the HAs than to the FAs. Increasing salinity from 0 to 5.5‰ decreased sorption to dissolved humic substances in the ACW and Baltic Sea water samples. Along the salinity gradient, the sorption of compounds to organic material decreased when the salinity increased. Particulate organic matter sorbed model compounds per unit of carbon more than dissolved organic matter. Along the studied salinity gradient, the freely dissolved portion increased from 10 to 29% to 52 to 80% in the coastal water samples, mainly because of the increasing salinity and changes in DOC and quality of POC. Environ. Toxicol. Chem. 2010;29:2443–2449. © 2010 SETAC
The influence of natural organic matter on the toxicity of multiwalled carbon nanotubes
Authors: Edgington Aaron J. , Roberts Aaron P. , Taylor Leigh M. , Alloy Matt M. , Reppert Jason , Rao Apparao M. , Mao Jingdong , Klaine Stephen J. 
Published: July 2010

Abstract
Engineered carbon nanostructures, such as multiwalled carbon nanotubes (MWNTs), are inherently hydrophobic and are not readily stable in aqueous media. However, the aqueous stability and bioavailability of these nanotubes may be influenced by the water quality parameters such as ionic strength, pH, and natural organic matter (NOM). Natural organic matter adsorbs onto the surface of MWNTs, effectively covering the hydrophobic surface and resulting in increased aqueous stability. This enhanced stability is likely to lead to an increased residence time in the water column and increased exposure times for pelagic organisms. In the current study, NOM from three different river systems in the southeast United States increased the stability of MWNT suspensions. The effects of these suspensions were evaluated using acute and chronic bioassays with Daphnia magna and Ceriodaphnia dubia. The 96-h LC50 for D. magna exposed to MWNTs suspended in Suwannee River (USA) NOM was approximately 2.0 mg/L and was not significantly influenced by NOM concentrations ranging from 1.79 to 18.5 mg/L DOC. However, there were differences in 96-h LC50 values among different sources of NOM (Suwannee, Black, and Edisto Rivers, USA). Daphnid growth was reduced in both D. magna and C. dubia, whereas reproduction was reduced in C. dubia. Characterization of the different NOM sources and MWNT suspensions was conducted. Visual inspection using transmission electron microscopy (TEM) and gut elimination observations suggested that the toxicity was attributable to ingested MWNTs clogging the gut tract of D. magna. The TEM micrographs indicated that MWNTs can disaggregate within the gut tract, but single MWNTs are unable to absorb across the gut lumen. Environ. Toxicol. Chem. 2010;29:2511–2518. © 2010 SETAC