Continuous critical current measurement of high-temperature superconductor tapes with magnetic substrates using magnetic-circuit method

The critical current (I(c)) of high-temperature superconductor (HTS) tapes has to be examined not only for short samples, but also for the entire tape, because local weak points can possibly lead to the quenching of the whole HTS device. Some methods were reported for continuous I(c) measurement along the length of a HTS tape, but few of them were applicable to tapes with magnetic substrates represented by YBa2Cu3O(7-δ)(YBCO)-coated conductors based on Ni5W alloy substrate by rolling assisted bi-axially textured substrate process. We previously presented a contact-free method using magnetic circuits to measure I(c) continuously of long HTS tapes, namely the magnetic-circuit (MC) method. This method has been previously applied with high speed and resolution to measure I(c) of HTS tapes with non-magnetic substrates, due to its resistance to noise aroused by mechanical vibration. In this work, its ability to measure HTS tapes with magnetic substrates is demonstrated both theoretically and experimentally. A 100 m long commercial YBCO tape based on Ni5W alloy substrate was measured and regular I(c) fluctuations were discovered. The MC method can be a powerful tool for quality control of HTS tapes, especially for tapes with magnetic substrates.

Transcriptome deep-sequencing and clustering of expressed isoforms from Favia corals

BACKGROUND

Genomic and transcriptomic sequence data are essential tools for tackling ecological problems. Using an approach that combines next-generation sequencing, de novo transcriptome assembly, gene annotation and synthetic gene construction, we identify and cluster the protein families from Favia corals from the northern Red Sea.

RESULTS

We obtained 80 million 75 bp paired-end cDNA reads from two Favia adult samples collected at 65 m (Fav1, Fav2) on the Illumina GA platform, and generated two de novo assemblies using ABySS and CAP3. After removing redundancy and filtering out low quality reads, our transcriptome datasets contained 58,268 (Fav1) and 62,469 (Fav2) contigs longer than 100 bp, with N50 values of 1,665 bp and 1,439 bp, respectively. Using the proteome of the sea anemone Nematostella vectensis as a reference, we were able to annotate almost 20% of each dataset using reciprocal homology searches. Homologous clustering of these annotated transcripts allowed us to divide them into 7,186 (Fav1) and 6,862 (Fav2) homologous transcript clusters (E-value ≤ 2e(-30)). Functional annotation categories were assigned to homologous clusters using the functional annotation of Nematostella vectensis. General annotation of the assembled transcripts was improved 1-3% using the Acropora digitifera proteome. In addition, we screened these transcript isoform clusters for fluorescent proteins (FPs) homologs and identified seven potential FP homologs in Fav1, and four in Fav2. These transcripts were validated as bona fide FP transcripts via robust fluorescence heterologous expression. Annotation of the assembled contigs revealed that 1.34% and 1.61% (in Fav1 and Fav2, respectively) of the total assembled contigs likely originated from the corals' algal symbiont, Symbiodinium spp.

CONCLUSIONS

Here we present a study to identify the homologous transcript isoform clusters from the transcriptome of Favia corals using a far-related reference proteome. Furthermore, the symbiont-derived transcripts were isolated from the datasets and their contribution quantified. This is the first annotated transcriptome of the genus Favia, a major increase in genomics resources available in this important family of corals.

Tax-interacting protein 1 coordinates the spatiotemporal activation of Rho GTPases and regulates the infiltrative growth of human glioblastoma

PDZ domains represent one group of the major structural units that mediate protein interactions in intercellular contact, signal transduction and assembly of biological machineries. TIP-1 protein is composed of a single PDZ domain that distinguishes TIP-1 from other PDZ domain proteins that more often contain multiple protein domains and function as scaffolds for protein complex assembly. However, the biological functions of TIP-1, especially in cell transformation and tumor progression, are still controversial as observed in a variety of cell types. In this study, we have identified ARHGEF7, a guanine nucleotide exchange factor (GEF) for Rho GTPases, as one novel TIP-1 interacting protein in human glioblastoma cells. We found that the presence of TIP-1 protein is essential to the intracellular redistribution of ARHGEF7 and rhotekin, one Rho effector, and the spatiotemporally coordinated activation of Rho GTPases (RhoA, Cdc42 and Rac1) in migrating glioblastoma cells. TIP-1 knockdown resulted in both aberrant localization of ARHGEF7 and rhotekin, as well as abnormal activation of Rho GTPases that was accompanied with impaired motility of glioblastoma cells. Furthermore, TIP-1 knockdown suppressed tumor cell dispersal in orthotopic glioblastoma murine models. We also observed high levels of TIP-1 expression in human glioblastoma specimens, and the elevated TIP-1 levels are associated with advanced staging and poor prognosis in glioma patients. Although more studies are needed to further dissect the mechanism(s) by which TIP-1 modulates the intracellular redistribution and activation of Rho GTPases, this study suggests that TIP-1 holds potential as both a prognostic biomarker and a therapeutic target of malignant gliomas.

Forty-eight-week retrospective study of telbivudine and lamivudine treatment in patients with hepatitis B-related cirrhosis

The aim of this study was to evaluate the efficacy and safety of telbivudine 600 mg/day compared with lamivudine 100 mg/day for 48 weeks of treatment in patients with hepatitis B-related cirrhosis. Data were reviewed retrospectively from 165 hepatitis B-related cirrhotic patients (55 compensated patients and 110 decompensated) who received antiviral therapy with telbivudine or lamivudine. Serum alanine aminotransferase (ALT) and hepatitis B virus (HBV) DNA levels, hepatitis B e antigen (HBeAg) loss and seroconversion, histological improvement and various adverse events (AEs) were evaluated. Baseline characteristics were comparable. ALT levels declined but showed no significant difference in treatment with telbivudine or lamivudine (P > 0.05). Reduction in serum HBV DNA levels was evident by week 4 in compensated HBV-related cirrhosis patients (telbivudine, 2.34 log10 copies/mL; lamivudine, 2.07 log10 copies/mL; P = 0.02) and persisted by week 8. Patients administrated with telbivudine had slightly greater HBeAg loss and seroconversion than patients with lamivudine, but the difference was not statistically significant (P > 0.05). Accumulative HBeAg loss was seen at week 48 (25.0% vs 25.0% and 13.3% vs 10.0% for telbivudine vs lamivudine in compensated and decompensated cirrhotic groups, respectively), as well as HBeAg seroconversion (15.0% vs 8.3% and 8.9% vs 6.7%). Mean Knodell Histologic Activity Index scores decreased in both compensated and decompensated cirrhotic patients (3.92 vs 3.64, 3.85 vs 3.73, for telbivudine vs lamivudine). Telbivudine and lamivudine were both well tolerated with minor AEs. The results of this study support telbivudine as an effective therapy for patients with both compensated and decompensated HBV-related cirrhosis.

Single action potentials and subthreshold electrical events imaged in neurons with a fluorescent protein voltage probe

Monitoring neuronal electrical activity using fluorescent protein-based voltage sensors has been limited by small response magnitudes and slow kinetics of existing probes. Here we report the development of a fluorescent protein voltage sensor, named ArcLight, and derivative probes that exhibit large changes in fluorescence intensity in response to voltage changes. ArcLight consists of the voltage-sensing domain of Ciona intestinalis voltage-sensitive phosphatase and super ecliptic pHluorin that carries the point mutation A227D. The fluorescence intensity of ArcLight A242 decreases by 35% in response to a 100 mV depolarization when measured in HEK293 cells, which is more than five times larger than the signals from previously reported fluorescent protein voltage sensors. We show that the combination of signal size and response speed of these new probes allows the reliable detection of single action potentials and excitatory potentials in individual neurons and dendrites.

Inorganic phosphorus fractionation and its translocation dynamics in a low-P soil

The translocation of different inorganic phosphorus (Pi) forms in a low-P soil (Langfang experimental station, Hebei province, China) over time was investigated using P fractionation extraction and a (32)P tracer technique. The L-value and P availability of the soil was assessed using 5 different maize genotype (Zea mays L.) cultivars. The results showed that the different Pi fractions in the soil increased in the order of H(2)SO(4)-extractable P (Ca(10)-P) > Na(3)C(6)H(5)O(7)-Na(2)S(2)O(4)-extractable P (O-P) > NH(4)Ac-extractable P (Ca(8)-P) > NaHCO(3)-extractable P (Ca(2)-P), NH(4)F-extractable P (Al-P), NaOH-Na(2)CO(3)-extractable P (Fe-P), and the content of plant-unavailable P (Ca(10)-P + O-P) was high, up to 79.1%, which might be an important reason for P deficiency in this low-P soil. The (32)P tracer results showed that after the addition of (32)P-Pi to the soil with no P fertilizer applied for 25 d, 29.0% of (32)P was quickly transformed into Ca(2)-P (rapidly available P), and 66.1% of (32)P was transformed into Al-P, Fe-P and Ca(8)-P (slowly available P). Only 5.0% of (32)P was transformed into O-P and Ca(10)-P (plant-unavailable P). Moreover, in the soil with P fertilizer applied, (32)P transformation into Ca(2)-P increased, and the transformation into Ca(8)-P + Fe-P + AL-P and O-P, Ca(10)-P significantly decreased compared to the soil with no P fertilizer applied (p < 0.05). This result suggested a higher rate for water-soluble P transformation to slowly available and plant-unavailable P in P deficient soil than in soil with sufficient P. The results of maize L-value determination showed that different genotype maize cultivars had different soil P-use efficiency and low-P tolerance mechanisms. Low-P tolerant cultivar DSY-32 regulated soil P-use efficiency and plant P content according to exogenous P fertilizer application. However, another low-P tolerant cultivar, DSY-2, used soil P more efficiently, regardless of the application of exogenous P.

CM2 antigen, a potential novel molecule participating in glucuronide transport on rat hepatocyte canalicular membrane

The polarized molecules predominately distributing at hepatocyte canalicular surface play a vital role in disclosing the process of bile formation and etiopathogenisis of cholestatic live diseases. Therefore, it is important to find novel polarized molecules on hepatocyte canalicular membrane. In the present study, canalicular membrane vesicles (CMVs) isolated from rat hepatocyte by density gradient centrifugation were used as immunogens to produce hybridoma and 46 strains of monoclonal antibodies (mAb) against CMVs were obtained. With a series of morphological assay methods, including immunohistochemistry, immunofluorescence and immuno-electron microscope, the antigens recognized by canalicular mAb1 (CM1) and canalicular mAb2 (CM2) were confirmed to predominately distribute at hepatocyte canalicular membrane. Transport activity assay revealed that CM2 could inhibit ATP-dependent E217βG uptake of rat hepatocyte CMVs. Meanwhile, Western blotting analysis showed that the molecular mass of CM2 antigen was approximately 110kDa, which was much less than Mr 180kDa of multidrug resistance-associated protein 2 (MRP2) involved in glucuronide transport. These data indicated that CM2 antigen might be a potential novel molecule participating in glucuronide transport on the hepatocyte canalicular membrane.

Genetically encoded fluorescent voltage sensors using the voltage-sensing domain of Nematostella and Danio phosphatases exhibit fast kinetics

A substantial increase in the speed of the optical response of genetically encoded fluorescent protein voltage sensors (FP voltage sensors) was achieved by using the voltage-sensing phosphatase genes of Nematostella vectensis and Danio rerio. A potential N. vectensis voltage-sensing phosphatase was identified in silico. The voltage-sensing domain (S1-S4) of the N. vectensis homolog was used to create an FP voltage sensor called Nema. By replacing the phosphatase with a cerulean/citrine FRET pair, a new FP voltage sensor was synthesized with fast off kinetics (Tau(off)<5ms). However, the signal was small (ΔF/F=0.4%/200mV). FP voltage sensors using the D. rerio voltage-sensing phosphatase homolog, designated Zahra and Zahra 2, exhibited fast on and off kinetics within 2ms of the time constants observed with the organic voltage-sensitive dye, di4-ANEPPS. Mutagenesis of the S4 region of the Danio FP voltage sensor shifted the voltage dependence to more negative potentials but did not noticeably affect the kinetics of the optical signal.

Partial loss compensation in dielectric-loaded plasmonic waveguides at near infra-red wavelengths

We report on the fabrication and characterization of straight dielectric-loaded surface plasmon polaritons waveguides doped with lead-sulfide quantum dots as a near infra-red gain medium. A loss compensation of ~33% (an optical gain of ~143 cm⁻¹) was observed in the guided mode. The mode propagation, coupling efficiency and stimulated emission were characterized using leakage radiation microscopy. The guided mode signature was separated using spatial filters in the Fourier plane of the microscope for quantitative measurements of stimulated emission.

Prominin-1 localizes to the open rims of outer segment lamellae in Xenopus laevis rod and cone photoreceptors

PURPOSE

Prominin-1 expresses in rod and cone photoreceptors. Mutations in the prominin-1 gene cause retinal degeneration in humans. In this study, the authors investigated the expression and subcellular localization of xlProminin-1 protein, the Xenopus laevis ortholog of prominin-1, in rod and cone photoreceptors of this frog.

METHODS

Antibodies specific for xlProminin-1 were generated. Immunoblotting was used to study the expression and posttranslational processing of xlProminin-1 protein. Immunocytochemical light and electron microscopy and transgenesis were used to study the subcellular distribution of xlProminin-1.

RESULTS

xlProminin-1 is expressed and is subject to posttranslational proteolytic processing in the retina, brain, and kidney. xlProminin-1 is differently expressed and localized in outer segments of rod and cone photoreceptors of X. laevis. Antibodies specific for the N or C termini of xlProminin-1 labeled the open rims of lamellae of cone outer segments (COS) and the open lamellae at the base of rod outer segments (ROS). By contrast, anti-peripherin-2/rds antibody, Xper5A11, labeled the closed rims of cone lamellae adjacent to the ciliary axoneme and the rims of the closed ROS disks. The extent of labeling of the basal ROS by anti-xlProminin-1 antibodies varied with the light cycle in this frog. The entire ROS was also faintly labeled by both antibodies, a result that contrasts with the current notion that prominin-1 localizes only to the basal ROS.

CONCLUSIONS

These findings suggest that xlProminin-1 may serve as an anti-fusogenic factor in the regulation of disk morphogenesis and may help to maintain the open lamellar structure of basal ROS and COS disks in X. laevis photoreceptors.

P4-01-17: TIMP-1 Over-Expression Confers Resistance of MCF-7 Breast Cancer Cells to Fulvestrant

Background

Endocrine resistance represents a major challenge in the management of estrogen receptor (ER) positive breast cancer. Currently no predictive biomarkers for endocrine resistance in ERpositive breast cancer patients are in clinical use.

In a clinical study, patients with metastatic breast cancer and high levels of serum Tissue Inhibitor of Metalloproteinases-1 (TIMP-1) had less benefit from endocrine therapy than patients with a lower level of serum TIMP-1 [1].

Therefore, we evaluated the association between TIMP-1 and response to endocrine therapy using an in vitro approach.

We have previously presented initial results on TIMP-1 and response to endocrine therapy [2].

Materials and Methods: MCF-7 cells were stably transfected with pcDNA3.1(Hyg)-TIMP-1 plasmid, and a panel of 11 subclones with different expression levels of TIMP-1 was generated. TIMP-1 expression levels were confirmed using enzyme-linked immunosorbent assay (ELISA).

Four subclones with high or low TIMP-1 expression were analyzed for the growth response to estrogen, 4-hydroxytamoxifen and fulvestrant. These four subclones were analyzed for protein expression by western blotting. All subclones were analyzed by whole human genome oligo microarrays 4×44K for determination of gene expression levels. Data were analyzed using the limma R/Bioconductor package. Paired-end Solexa sequencing was applied to selected subclones with high and low TIMP-1 levels to identify transcriptomic changes.

Results: High expression of TIMP-1 was associated with resistance to fulvestrant, whereas growth response to either estrogen or 4-hydroxytamoxifen was independent of TIMP-1 expression levels. High expression of TIMP-1 protein and mRNA was associated with undetectable levels of progesterone receptor (PgR) protein and mRNA whereas ER protein and mRNA levels were unaffected by TIMP-1. To characterize the potential role of TIMP-1 in estrogen signaling we analyzed the expression of reported estrogen-responsive genes and no general change was observed. We identified genes that correlated positively or negatively to TIMP-1 expression. Among the identified genes was PgR, which is a direct target for ER.

Conclusion: Our data suggest that a high expression of TIMP-1 in vitro is associated with resistance to fulvestrant but not to 4-hydroxytamoxifen. Estrogen-regulated genes are not generally affected by changes in TIMP-1 expression levels and therefore TIMP-1 appears to affect endocrine resistance through other mechanisms than globally regulating ER signaling. However, high expression of TIMP-1 is associated with loss of PgR and this may be related to the resistance towards fulvestrant.

References:

[1] Lipton, A et al: Serum TIMP-1 and Response to the Aromatase Inhibitor Letrozole Versus Tamoxifen in Metastatic Breast Cancer. J Clin Oncol; 2008; 26;(16); 2653–8

[2] Effect of TIMP-1 Overexpression on Endocrine Sensitivity of MCF-7 ER-positive Human Breast Cancer Cells In Vitro. Cancer Res; 2009; 69(24 suppl); abstract nr 2029

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P4-01-17.

A modification of flattening filter free linac for IMRT

PURPOSE

This study investigates the benefits of a modified flattening filter free (FFF) linac over the standard (STD) linac equipped with the flattening filter. Energy and angular spread of the electron beam of the FFF linac were modified. Modification of FFF beam parameters is explored to maximize the monitor unit efficiency and to minimize the head scatter in IMRT delivery for large target volumes or targets lying away from the central axis.

METHODS

The EGSnrc code is used to model FFF and STD linacs and study basic beam properties for both linac types in various beam configurations. Increasing energy of FFF linac results in similar beam attenuation properties and maximized dose rate compared to STD linac. Matching beam attenuation properties allows a more direct exploration of beam flatness of FFF linac in regard to IMRT delivery, especially away from the central axis where the effective dose rate is considerably smaller than the one at the central axis. Flatness of open beam dose profile of FFF linac is improved by increasing the angular spread of the electron beam. The resulting dose rate within the treatment field and outside of the field (peripheral dose) are characterized and compared to the unmodified FFF and STD linacs,

RESULTS

In order to match beam penetration properties, the energy of FFF is adjusted from 6.5 to 8.0 MeV for small to medium field sizes and from 6.5 to 8.5 MeV for larger ones. Dose rate of FFF vs STD linac increased by a factor of 1.9 (6.5 MeV) and 3.4-4.1 (8.0-8.5 MeV). Adjusting the mean angular spread of the electron beam from 0 degrees to 5 degrees-10 degrees resulted in complete flattening of photon beam for field sizes between 10 x 10 cm2 and 15 x 15 cm2 and partial flattening for field sizes from 15 x 15 cm2 to 30 x 30 cm2. Values of angular spread > or =14 degrees are not recommended as they exceed the opening of the primary collimator, affecting the area at the edges of the field. FFF fields of sizes smaller than 6 x 6 cm2 are already flat and beam flattening is not necessary. Overall, the angular spread of 5 degrees-10 degrees is sufficient and can satisfactorily flatten open beam dose profiles even for larger field sizes. Increasing the electron beam angular spread amounts to a slight decrease of dose rate of FFF linac. However, for angular spread, 5 degrees-10 degrees dose rate factor of FFF vs STD is still about 1.6-2.6, depending on the field size (and the adjusted energy). Similarly, in case of peripheral dose, a moderate increase in dose can be observed for angular spread of 5 degrees-10 degrees and for field sizes 10 x 10 cm2 to 30 x 30 cm2. Lastly, beam flatness of not modified FFF linac can be conveniently described by an analytical function representing a ratio of STD vs FFF doses: 1 + b|r|(n).

CONCLUSIONS

A modified FFF beamline with increased energy and electron beam angular spread results in satisfactory flattened beam and high dose rate within the field. Peripheral dose remaining at similar (or smaller) level than that of STD linac for the same delivered dose within the treatment field.