bluuebunny/crossref_metadata_2025_split huggingface dataset:
Binding Dynamics of Hepatitis C Virus' NS5A Amphipathic Peptide to Cell and Model Membranes
Authors: Cho Nam-Joon , Cheong Kwang Ho , Lee ChoongHo , Frank Curtis W. , Glenn Jeffrey S. 
Published: April 2007

ABSTRACT
Membrane association of the hepatitis C virus NS5A protein is required for viral replication. This association is dependent on an N-terminal amphipathic helix (AH) within NS5A and is restricted to a subset of host cell intracellular membranes. The mechanism underlying this specificity is not known, but it may suggest a novel strategy for developing specific antiviral therapy. Here we have probed the mechanistic details of NS5A AH-mediated binding to both cell-derived and model membranes by use of biochemical membrane flotation and quartz crystal microbalance (QCM) with dissipation. With both assays, we observed AH-mediated binding to model lipid bilayers. When cell-derived membranes were coated on the quartz nanosensor, however, significantly more binding was detected, and the QCM-derived kinetic measurements suggested the existence of an interacting receptor in the target membranes. Biochemical flotation assays performed with trypsin-treated cell-derived membranes exhibited reduced AH-mediated membrane binding, while membrane binding of control cytochrome b5 remained unaffected. Similarly, trypsin treatment of the nanosensor coated with cellular membranes abolished AH peptide binding to the cellular membranes but did not affect the binding of a control lipid-binding peptide. These results therefore suggest that a protein plays a critical role in mediating and stabilizing the binding of NS5A's AH to its target membrane. These results also demonstrate the successful development of a new nanosensor technology ideal both for studying the interaction between a protein and its target membrane and for developing inhibitors of that interaction.
The Effect of Oculo-Acupuncture on Recovery from Ethylene Glycol-Induced Acute Renal Injury in Dogs
Authors: Liu Jianzhu , Song Kun-Ho , You Myung-Jo , Son Dong-Soo , Cho Sung-Whan , Kim Duck-Hwan 
Published: April 2007

The potential recovery effect by oculo-acupuncture (OA) on ethylene glycol-induced acute renal injury in dogs was investigated. Acute renal damage was induced by ingestion of ethylene glycol in six mongrel dogs. The dogs were assigned to control (three dogs) and experimental (three dogs) groups. The control group did not receive any treatment, while the experimental group was treated with oculo-acupuncture at kidney/urinary bladder region plus zhong jiao region of the eyes after the induction of renal damage. Serum blood urea nitrogen (BUN), creatinine, sodium ( Na ), chloride ( Cl ), and potassium ( K ) were measured in both control and experimental groups. The blood RBC and Hb were also examined. The serum BUN and creatinine activities in the experimental group were lower than those in the control group, the serum Na and Cl had the irregular change in both groups, and the blood Hb in the control and experimental group showed decreasing tendency. Significant differences were observed on the 3rd and 7th day in BUN, 7th day in creatinine, 2nd day in Na and Cl , and 7th day in Hb when compared to the control group. Whereas, serum K concentration and RBC in the experimental group did not change significantly. The recovery findings of the renal injury were also observed in the experimental group histopathologically. In conclusion, OA therapy (kidney/urinary bladder region plus zhong jiao region) was effective for recovery of the renal injury induced by ethylene glycol in dogs.
An evaluation of methods for imputation of missing trace element data in groundwaters
Authors: Dickson Bruce L. , Giblin Angela M. 
Published: April 2007

Groundwater data-sets with pH and major cation–anion chemistry are widely available but data that include trace metals are much rarer. This paper examines two methods of data imputation to predict U concentrations using pH, major cations, anions and F in a data-set where some of the U concentrations are missing. The methods evaluated were self-organizing maps (SOM) and expectation maximization (EM). Evaluations were made using a groundwater data-set of 187 samples from NSW and Victoria, which contained a wide range of U concentrations up to 225 μg/l. Tests made by setting 25% and 50% of the U concentrations to missing showed that, at 25% missing, SOM gave reasonable estimates, identifying all the samples with higher U. EM did not clearly identify the higher samples. At 50% missing, neither method could accurately identify the higher U concentrations. Thus, imputation using samples with missing data included in the training data-set does not appear to be practical. However, a SOM pre-trained on a data-set with no missing U concentrations may be used to impute U concentrations for samples with 100% missing U data. Training using the original data-set and then imputing concentrations for a second set of 360 samples showed that the samples with higher measured U concentrations could generally be identified, but that other samples were also estimated to be U-rich. This method could substantially reduce the number of samples in a large data-set requiring further investigation.
The performance of imputation for U reflects the complex interaction of water chemistry, geology and mineralogy that actually determines the U concentrations. Imputation is a useful method for improving estimates of data statistics. SOM, through its model-free approach, is a useful addition to the numerical analysis toolbox for geochemists.
S-phase checkpoints regulate Apo2 ligand/TRAIL and CPT-11–induced apoptosis of prostate cancer cells
Authors: Ray Subrata , Shyam Sunitha , Fraizer Gail C. , Almasan Alexandru 
Published: April 2007

Abstract
As S-phase checkpoints play critical roles in maintaining genomic integrity and replicating the human genome correctly, understanding the molecular mechanism by which they regulate the therapeutic response is of great interest. Previously, we reported that the cytotoxic effect of a zinc-bound form of Apo2 ligand/tumor necrosis factor–related apoptosis-inducing ligand (Apo2L/TRAIL), which is currently evaluated in clinical trials, in combination with low-dose CPT-11, induces apoptosis of C4-2 human prostate cancer cells and tissues. Here, we show that apoptosis, induced synergistically by this combination treatment, was associated with accumulation of cells in early S phase, indicated by cell cycle analyses, increased proliferating cell nuclear antigen, and Chk2-Thr68 phosphorylation in tumors xenografted in mice. The combination treatment induced an S-phase checkpoint response through activation of Chk2 and Chk1 by the ataxia telangiectasia mutated and ataxia telangiectasia mutated and Rad3 related kinases, leading to phosphorylation and decreased Cdc25A levels. Cdc25A-dependent regulation of cyclin-dependent kinase 2 (Cdk2) and changes in association of p21WAF1/CIP1 and hSpy1 with Cdk2 resulted in inhibition of Cdk2-associated kinase activity. Knockdown of ataxia telangiectasia mutated/Chk2 and ataxia telangiectasia mutated and Rad3 related/Chk1 by small inhibitory RNAs abrogated the S-phase checkpoint and accelerated apoptosis, resulting in caspase-3 activation and poly(ADP-ribose) polymerase 1 cleavage following combination treatment. Thus, Apo2L/TRAIL + CPT-11 treatment–induced apoptosis is regulated through an S-phase checkpoint controlled by the Chk2-Cdc25A and Chk1-Cdc25A pathways and inhibition of Cdk2-associated kinase activity. Low-dose CPT-11 and aphidicolin increased the proportion of S-phase cells and sensitized cells to Apo2L/TRAIL, by inducing phosphatidylserine externalization, caspase activation, and poly(ADP-ribose) polymerase 1 cleavage. Combinations with S-phase arrest–inducing chemotherapeutic drugs may represent promising avenues for clinical development of Apo2L/TRAIL. [Mol Cancer Ther 2007;6(4):1368–78]
Dasatinib (BMS-354825) inhibits Stat5 signaling associated with apoptosis in chronic myelogenous leukemia cells
Authors: Nam Sangkil , Williams Ann , Vultur Adina , List Alan , Bhalla Kapil , Smith David , Lee Francis Y. , Jove Richard 
Published: April 2007

Abstract
Dasatinib (BMS-354825) is a novel, oral, potent, multi-targeted kinase inhibitor of Bcr-Abl and Src family kinases (SFK) and is a promising cancer therapeutic agent. Preclinical data indicate that dasatinib is 325-fold more potent than imatinib against cells expressing wild-type Bcr-Abl, and that dasatinib is active against 18 of 19 Bcr-Abl mutations known to cause imatinib resistance. Phase I clinical data show that dasatinib is well tolerated and highly effective for the treatment of imatinib-resistant/imatinib-intolerant chronic myelogenous leukemia (CML) and Philadelphia chromosome–positive acute lymphoblastic leukemia. However, the molecular mechanism of action of dasatinib is not fully understood. In this study, we confirm that dasatinib inhibits tyrosine phosphorylation of SFKs, including Src, Hck, and Lyn, in K562 human CML cells. Significantly, downstream signal transducer and activator of transcription 5 (Stat5) signaling is also blocked by dasatinib as shown by decreases in levels of phosphorylated Stat5 and Stat5 DNA-binding activities. In addition, dasatinib down-regulates expression of Stat5 target genes, including Bcl-x, Mcl-1, and cyclin D1. Consistent with these results, blockade of Stat5 signaling by dasatinib is accompanied by inhibition of cell proliferation and induction of apoptosis. Surprisingly, Stat5 DNA-binding activities are enhanced with increasing cell density, which is associated with resistance to apoptosis by dasatinib. Our findings indicate that inhibition of Stat5 signaling downstream of Bcr-Abl/SFKs contributes to the action of dasatinib, and, conversely, that increasing cell density up-regulates Stat5 activation and confers resistance to dasatinib. Moreover, the level of phosphorylated Stat5 in CML cells represents a mechanistically relevant biomarker for monitoring inhibition of Bcr-Abl signaling by dasatinib in CML patients using convenient immunocytochemical assays. [Mol Cancer Ther 2007;6(4):1400–5]
Inhibition of both focal adhesion kinase and insulin-like growth factor-I receptor kinase suppresses glioma proliferation in vitro and in vivo
Authors: Liu Ta-Jen , LaFortune Tiffany , Honda Toshiyuki , Ohmori Osamu , Hatakeyama Shinji , Meyer Thomas , Jackson Dowdy , de Groot John , Yung W.K. Alfred 
Published: April 2007

Abstract
Multiple genetic aberrations in human gliomas contribute to their highly infiltrative and rapid growth characteristics. Focal adhesion kinase (FAK) regulates tumor migration and invasion. Insulin-like growth factor-I receptor (IGF-IR), whose expression correlates with tumor grade, is involved in proliferation and survival. We hypothesized that inhibiting the phosphorylation of FAK and IGF-IR by NVP-TAE226 (hereafter called TAE226), a novel dual tyrosine kinase inhibitor of FAK and IGF-IR, would suppress the growth and invasion of glioma cells. In culture, TAE226 inhibited extracellular matrix–induced autophosphorylation of FAK (Tyr397). TAE226 also inhibited IGF-I–induced phosphorylation of IGF-IR and activity of its downstream target genes such as MAPK and Akt. TAE226 retarded tumor cell growth as assessed by a cell viability assay and attenuated G2-M cell cycle progression associated with a decrease in cyclin B1 and phosphorylated cdc2 (Tyr15) protein expression. TAE226 treatment inhibited tumor cell invasion by at least 50% compared with the control in an in vitro Matrigel invasion assay. Interestingly, TAE226 treatment of tumor cells containing wild-type p53 mainly exhibited G2-M arrest, whereas tumor cells bearing mutant p53 underwent apoptosis. Induction of apoptosis by TAE226 was substantiated by detection of caspase-3/7 activation and poly(ADP-ribose) polymerase cleavage and by an Annexin V apoptosis assay. More importantly, TAE226 treatment significantly increased the survival rate of animals in an intracranial glioma xenograft model. Collectively, these data show that blocking the signaling pathways of FAK and IGF-IR with TAE226 has the potential to be an efficacious treatment for human gliomas. [Mol Cancer Ther 2007;6(4):1357–67]
Activation of clinically used anthracyclines by the formaldehyde-releasing prodrug pivaloyloxymethyl butyrate
Authors: Cutts Suzanne M. , Swift Lonnie P. , Pillay Vinochani , Forrest Robert A. , Nudelman Abraham , Rephaeli Ada , Phillips Don R. 
Published: April 2007

Abstract
The anthracycline group of compounds is extensively used in current cancer chemotherapy regimens and is classified as topoisomerase II inhibitor. However, previous work has shown that doxorubicin can be activated to form DNA adducts in the presence of formaldehyde-releasing prodrugs and that this leads to apoptosis independently of topoisomerase II–mediated damage. To determine which anthracyclines would be useful in combination with formaldehyde-releasing prodrugs, a series of clinically relevant anthracyclines (doxorubicin, daunorubicin, idarubicin, and epirubicin) were examined for their capacity to form DNA adducts in MCF7 and MCF7/Dx (P-glycoprotein overexpressing) cells in the presence of the formaldehyde-releasing drug pivaloyloxymethyl butyrate (AN-9). All anthracyclines, with the exception of epirubicin, efficiently yielded adducts in both sensitive and resistant cell lines, and levels of adducts were similar in mitochondrial and nuclear genomes. Idarubicin was the most active compound in both sensitive and resistant cell lines, whereas adducts formed by doxorubicin and daunorubicin were consistently lower in the resistant compared with sensitive cells. The adducts formed by doxorubicin, daunorubicin, and idarubicin showed the same DNA sequence specificity in sensitive and resistant cells as assessed by λ-exonuclease–based sequencing of α-satellite DNA extracted from drug-treated cells. Growth inhibition assays were used to show that doxorubicin, daunorubicin, and idarubicin were all synergistic in combination with AN-9, whereas the combination of epirubicin with AN-9 was additive. Although apoptosis assays indicated a greater than additive effect for epirubicin/AN-9 combinations, this effect was much more pronounced for doxorubicin/AN-9 combinations. [Mol Cancer Ther 2007;6(4):1450–9]
Phospholipid hydroperoxide glutathione peroxidase plays a role in protecting cancer cells from docosahexaenoic acid–induced cytotoxicity
Authors: Ding Wei-Qun , Lind Stuart E. 
Published: April 2007

Abstract
Docosahexaenoic acid (DHA; 22:6, n-3) is known to exert cytotoxic effects against various types of tumors via lipid peroxidation. Whereas several enzymes influence the response of cells to oxidative stress, only one enzyme, phospholipid hydroperoxide glutathione peroxidase (GPx-4), directly reduces lipid hydroperoxides in mammalian cells. The present study was designed to examine the involvement of GPx-4 in determining the effects of DHA addition to various human cancer cell lines. Although baseline levels of GPx-4 did not correlate with the relative sensitivity of human cancer cell lines to DHA, DHA reduced the level of protein expression of GPx-4 by at least 50% in all six lines. Knockdown of GPx-4 by small interfering RNA technique in a human ovarian cancer cell line significantly enhanced the cytotoxic effect of DHA in a time- and concentration-dependent manner. This cytotoxic effect of DHA was reversed by pretreatment with vitamin E, suggesting that the enhanced toxicity of GPx-4 knockdown is due to changes in the ability of the cells to handle oxidative stress. Neither baseline superoxide dismutase-1 nor catalase expression correlated with the relative sensitivity of the cells to DHA treatment. These results illustrate that susceptibility to the oxidative stress imposed by DHA, and possibly other therapeutic agents, is due to complex interactions among multiple antioxidant systems. The modulation of GPx-4 levels by DHA administration is of potential importance and may influence the cellular response to other oxidant stresses. [Mol Cancer Ther 2007;6(4):1467–74]
Combined effects of retinoic acid and histone deacetylase inhibitors on human neuroblastoma SH-SY5Y cells
Authors: De los Santos Maxy , Zambrano Alberto , Aranda Ana 
Published: April 2007

Abstract
All-trans retinoic acid (RA) causes differentiation of neuroblastoma cells, and retinoids have been used in clinical trials in children with advanced neuroblastoma. Combination of RA with histone deacetylase inhibitors (HDACi) could result in improved antitumorigenic activity. We have examined the effect of the HDACi trichostatin A (TSA), sodium butyrate, and suberoylanilide hydroxamic acid (SAHA), alone and in combination with RA in human neuroblastoma SH-SY5Y cells. At concentrations that cause sustained increase of histone H3 acetylation, HDACi produced extensive apoptotic cell death as shown by flow cytometry analysis and induction of poly(ADP-ribose) polymerase proteolysis. HDACi inhibited SH-SY5Y cell growth at a much larger extent than RA. This compound did not cause apoptosis and did not further increase HDACi-mediated cell death. In contrast, both types of drugs cooperated to inhibit cell growth, although synergistic effects were not found. In surviving cells, HDACi repressed cyclin D1 expression and increased the cyclin kinase inhibitors (CKI) p21Waf1/Cip1 and p27Kip1. Cyclin D1 was not affected by RA, but this retinoid also increased CKI levels. Induction of p21Waf1/Cip1 and p27Kip1 by HDACi was further enhanced in the presence of RA. This effect seems to be at least partially due to transcriptional stimulation of CKI gene expression because both types of drugs cooperated to increase CKI mRNA levels and to activate the CKI promoters in transient transfection assays. These results show the strong antitumorigenic effects of HDACi in neuroblastoma cells and reinforce the idea that combination therapy could be useful to inhibit tumor growth. [Mol Cancer Ther 2007;6(4):1425–32]
Use of fluorescent labeled anti–epidermal growth factor receptor antibody to image head and neck squamous cell carcinoma xenografts
Authors: Rosenthal Eben L. , Kulbersh Brian D. , King Teresa , Chaudhuri Tandra R. , Zinn Kurt R. 
Published: April 2007

Abstract
Physicians and surgeons rely on subtle tissue changes to detect the extent of tumors and the presence of residual disease in the clinical setting. The development of a cancer-specific fluorescent contrast agent has the potential to provide real-time tumor imaging in the clinic or operating room. Because epidermal growth factor receptor (EGFR) is highly overexpressed on the surface of head and neck squamous cell carcinoma (HNSCC), we sought to determine if fluorescently labeled anti-EGFR antibody could be used to image HNSCC xenografts in vivo. Cetuximab or control isotype-matched IgG1 was conjugated with the Cy5.5 fluorochrome and systemically injected into mice bearing human split thickness skin grafts, tumor cell line xenografts, transplanted human tumor xenografts, or mouse mesothelioma tumors. Xenografts were imaged by time-domain fluorescence imaging or fluorescence stereomicroscopy. Both imaging modalities detected specific uptake of cetuximab-Cy5.5 in HNSCC xenografts with significantly higher fluorescence levels relative to control IgG1-Cy5.5. Tumor xenograft fluorescence was higher compared with background (before injection), human split thickness skin grafts, or mouse mesothelioma tumors at 24, 48, and 72 h. Fluorescence was detected in multiple HNSCC tumor cell lines with variable EGFR expression levels. Mock resections of flank tumors using fluorescence stereomicroscopy showed that small (2 mm) specimens could be detected in the surgical wound bed. These results show the feasibility of using fluorescently labeled anti-EGFR antibody to detect human tumors in the surgical setting. [Mol Cancer Ther 2007;6(4):1230–8]
Effects of mating, breeding system and parasites on reproduction in hermaphrodites: pulmonate gastropods (Mollusca)
Authors: Jordaens Kurt , Dillen Lobke , Backeljau Thierry 
Published: April 2007

Abstract
There are approximately 20 000 pulmonate gastropod species that are all hermaphroditic and (with a few exceptions) can act in both (i.e., male and female) sexual roles. Life history traits such as growth (rate), age at first reproduction, fecundity, fertility, future survival and offspring survival are highly variable within pulmonate species, even among individuals of the same population. Here, we review some aspects of reproduction (availability of partners, size-dependent sex allocation, courtship, (multiple) mating, sperm longevity/viability, social facilitation), breeding system (self-fertilisation, outcrossing or mixed) and parasitism that may influence an individual's reproductive success and therefore account for part of the intraspecific variation in life history traits. A literature study showed that fecundity, fertility and/or growth are significantly affected by: i) the mating group size through changes in interference competition (e.g., crowding), breeding system and sex allocation; ii) individual body size with larger individuals producing more eggs than smaller individuals; iii) mating whereby female fitness may be positively or negatively affected; iv) social facilitation whereby female fitness is positively affected by the presence of conspecifics; v) the breeding system including the phenomena of inbreeding and outbreeding depression; and vi) parasites that may suppress or stimulate reproduction, especially egg-laying, in parasitised individuals. Moreover, multiple mating and multiple paternity seem very common in pulmonates. Interestingly, several of the above-mentioned aspects seem to interact or even act synergetically. Although many aspects of life history variation in pulmonate gastropods are still poorly understood which makes it difficult to draw general conclusions, pulmonates offer ample opportunities to study the evolution of major topics in evolution and life history strategies. Indeed, there is a growing number of basommatophoran and stylommatophoran model species, experimental setups and molecular, histological and histochemical techniques that are used to test current hypothesis on sex allocation, sexual selection (sexual conflict, sperm competition or cryptic female choice), the evolution of breeding systems and host-parasite interactions which will yield much information for the study of life history strategies as well.
Use of the dart apparatus by the hermaphroditic land snail Polymita muscarum (Lea, 1834)
Authors: Reyes-Tur Bernardo , Koene Joris 
Published: April 2007

AbstractMany species of pulmonate land snails are equipped with one or more so-called "love darts". Even though the number and shape of these calcareous darts vary considerably between species, dart use has only been investigated in very few species. Here, we redescribe the mating behaviour of Polymita muscarum because previous reports did not include the use of the dart apparatus. Mating in this hermaphroditic land snail can be divided into three stages: courtship, copulation and post-copulatory activity. During courtship, full eversion of the genital atrium is reached, thus exposing the sensitive zone, genital lobes and dart apparatus. We observed that P. muscarum pushes the everted dart apparatus repeatedly onto different parts of the partner's body and does not lose its dart after stabbing. Dissected specimens had a single, slender dart with a round base, a broad corona and a circular cross-section. We propose that the morphology of P. muscarum 's dart is consistent with the idea of simple darts needing to be stabbed more often in order to increase the transfer of mucus, which contains a biologically active substance (i.e. allohormone) that enhances the chances of paternity. Besides adding to the growing diversity in the use of love darts in land snails, these findings contribute to the understanding of the evolution of this peculiar reproductive act.