66 resultados para TC-1 tumor
Resumo:
Glioblastoma (GBM; grade IV astrocytoma) is the most malignant and common primary brain tumor in adults. Using combination of 2-DE and MALDI-TOF MS, we analyzed 14 GBM and 6 normal control sera and identified haptoglobin alpha 2 chain as an up-regulated serum protein in GBM patients. GBM-specific up-regulation was confirmed by ELISA based quantitation of haptoglobin (Hp) in the serum of 99 GBM patients as against lower grades (49 grade III/AA; 26 grade II/DA) and 26 normal individuals (p = 0.0001). Further validation using RT-qPCR on an independent set (n = 78) of tumor and normal brain (n = 4) samples and immunohistochemcial staining on a subset (n = 42) of above samples showed increasing levels of transcript and protein with tumor grade and were highest in GBM (p = < 0.0001 and < 0.0001, respectively). Overexpression of Hp either by stable integration of Hp cDNA or exogenous addition of purified Hp to immortalized astrocytes resulted in increased cell migration. RNAi-mediated silencing of Hp in glioma cells decreased cell migration. Further, we demonstrate that both human glioma and mouse melanoma cells overexpressing Hp showed increased tumor growth. Thus, we have identified haptoglobin as a GBM-specific serum marker with a role on glioma tumor growth and migration.
Resumo:
The superconducting transition temperatures in Bi2Ca1−xLnxSr2Cu2O8+δ, TlCa1−xLnxSr2Cu2O6+δ, and Tl0.8Ca1−xLnxBa2Cu23O6+δ (Ln=Y or rare earth) vary with composition and show a maximum at a specific value of x or δ. This observation suggests that an optimal carrier concentration is required to attain maximum Tc in such cuprates which seem to be two‐band systems
Magnetic properties of pure, Sr- and Ca-Doped La2NiO4+δ ceramics: Onset of high-Tc superconductivity
Resumo:
We present the results for the temperature and field dependence of the magnetic for ceramic materials of the composition La2−xMxNiO4, with M=Sr or Ca and 0≤x≤0.4. The onset of a strong diamagnetism has been observed at temperatures between 8 and 70 K, depending on sample composition, annealing conditions. and thermal cycling procedures. The results are similar to those obtained earlier for monocrystalline samples and are likewise interpreted as due to the onset of superconductivity in a minority phase. A comparison with the results for superconducting La1.8Sr0.2Cu0.9Ni0.1O4 ceramics is also made; this illustrates some unique features of the nickelate systems, such as the high values of the critical fields Hc1 and Hc2. The differences between monocrystalline and ceramic systems are also discussed.
Resumo:
We consider a model system of two interacting Fermi-liquids, one of which is light and the other much heavier. In the normal state the lighter component provides a quantum mechanical bath coupled 'ohmically' to the heavier component in the sense of Caldeira and Leggett, suppressing thereby the band (tunnelling) matrix elements of the heavier component. Thus we lose the energy of delocalization. On the other hand, a superconducting ordering stiffens the bath spectral function at low energies and so restores the tunnelling. The resulting regain of the delocalization energy bootstraps so as to stabilize the superconducting order that caused it. It is conceivable that the motions parallel to the easy ab-plane and along the hard c-axis may also effectively correspond to the light and the heavy Fermi-liquids, respectively.
Resumo:
The sharp increase in microwave power loss (the reverse of what has previously been reported) at the transition temperature in high-Tc superconducting systems such as YBaCu oxide (polycrystalline bulk and thin films obtained by the laser ablation technique) and BiPbSrCaCu oxide is reported. The differences between DC resistivity ( rho ) and the microwave power loss (related to microwave surface resistance) are analysed from the data obtained by a simultaneous measurement set-up. The influence of various parameters, such as preparation conditions, thickness and aging of the sample and the probing frequency (6-18 GHz), on the variation of microwave power loss with temperature is outlined.
Resumo:
Cubic cuprates (a not, vert, similar 18.6 Å) with a BaCuO2-type structure were obtained in the Ba-Pb-Cu-O and Ba-Bi-Cu-O systems by the reaction of the component oxides at a high temperature (1370-1420 K), followed by quenching. By annealing these phases in oxygen at 1070-1120 K, perovskite-like phase (a not, vert, similar 4.3 Å) of the formulae BaPb1-xCuxO3-y and BaBi1-xCuxO3-y (0 < x ? 0.5) were obtained. A perovskite of nominal composition BaPb0.25Tl0.25 Cu0.5O3-y, prepared by a similar procedure, was found to be superconducting with a Tc of not, vert, similar 70 K.
Resumo:
We have investigated tunneling conductances in disordered, normally conducting perovskite oxides close to the metal�insulator transition. We show that the normal state tunneling conductance of perovskite oxides can be cast in a general form G(V) = G0[1 + curly logical orV/V*curly logical orn] with 1?n?0.5 and where V* is an intrinsic energy scale. The exponent n graduall y increases from 0.5 to 1 as the metal-insulator (M-I) transition is approached. In the high-Tc Bi(2212) cuprates, the normally observed, linear G(V)(n=1) can be made sub-linear (n<1) by substitution of Ca with Y. From the similarity of the linear conductances, we suggest proximity to the M-I transition as a likely cause for this G(V)logical or, bar below V dependence. In systems showing linear conductances (nreverse similar, equals1), we find that ?G/?Vreverse similar, equalsG?0 with ?reverse similar, equals 1 and the intrinsic energy scale V*reverse similar, equals25�75 meV in the different oxides investigated.
Resumo:
Magnetization measurements below 50 K on ceramic La2?ySryCu1?xNixO4+? (y = 0.1, 0.2; 0less-than-or-equals, slantxless-than-or-equals, slant0.5) show a progressive diminution of superconducting properties with increasing x. The larger suppressive action of Ni in the y=0.1 system than that for y=0.2 is attributed to the hole-compensating effect of Ni3+. The assumption that nickel is in the 3+ state satisfactorily explains: (1) the reduction in hole concentration, (2) a right-shift of the Tc versus y curve with x, and (3) the low magnetic moment carried by Ni atoms, in the La2?ySryCu1?xNixO4+? system.
Resumo:
We point out how fluctuation of the phase of the superconducting order parameter can play a key role in our understanding of high Te superconductors. A simple universal criterion is given which illustrates why all oxide superconductors in contrast to classical superconductors ought to behave as a lattice of cooper pairs. T-c is to be thought of as the temperature of phase coherence or the temperature above which the lattice of Cooperpair 'melts' into a phase of Cooper-pair droplets that starts forming at T approximate to T-* . This is the pseudo-gap region. Quantum fluctuation of the phase predicts a superconductor to insulator phase transition for all underdoped materials.
Resumo:
We explored the effect of a novel synthetic triterpenoid compound cyano enone of methyl boswellates (CEMB) on various prostate cancer and glioma cancer cell lines. CEMB displayed concentration-dependent cytotoxic activity with submicromolar lethal dose 50% (LD(50)) values in 10 of 10 tumor cell lines tested. CEMB-induced cytotoxicity is accompanied by activation of downstream effector caspases (caspases 3 and 7) and by upstream initiator caspases involved in both the extrinsic (caspase 8) and intrinsic (caspase 9) apoptotic pathways. By using short interfering RNAs (siRNA), we show evidence that knockdown of caspase 8, DR4, Apaf-1, and Bid impairs CEMB-induced cell death. Similar to other proapoptotic synthetic triterpenoid compounds, CEMB-induced apoptosis involved endoplasmic reticulum stress, as shown by partial rescue of tumor cells by siRNA-mediated knockdown of expression of genes involved in the unfolded protein response such as IRE1 alpha, PERK, and ATF6. Altogether, our results suggest that CEMB stimulates several apoptotic pathways in cancer cells, suggesting that this compound should be evaluated further as a potential agent for cancer therapy. Mol Cancer Ther; 10(9); 1635-43. (C)2011 AACR.
Resumo:
Mycobacterium indicus pranii (MIP) is approved for use as an adjuvant (Immuvac/Cadi-05) in the treatment of leprosy. In addition, its efficacy is being investigated in clinical trials on patients with tuberculosis and different tumors. To evaluate and delineate the mechanisms by which autoclaved MIP enhances anti-tumor responses, the growth of solid tumors consisting of Sp2/0 (myeloma) and EL4 (thymoma) cells was studied in BALB/c and C57BL/6 mice, respectively. Treatment of mice with a single intra-dermal (i.d.) injection of MIP 3 days after Sp2/0 implantation greatly suppresses tumor growth. MIP treatment of tumor bearing mice lowers Interleukin (IL)6 but increases IL12p70 and IFN? amounts in sera. Also, increase in CD8+ T cell mediated lysis of specific tumor targets and production of high amounts of IL2 and IFN? by CD4+ T cells upon stimulation with specific tumor antigens in MIP treated mice is observed. Furthermore, MIP is also effective in reducing the growth of EL4 tumors; however, this efficacy is reduced in Ifn?-/- mice. In fact, several MIP mediated anti-tumor responses are greatly abrogated in Ifn?-/- mice: increase in serum Interleukin (IL)12p70 amounts, induction of IL2 and lysis of EL4 targets by splenocytes upon stimulation with specific tumor antigens. Interestingly, tumor-induced increase in serum IL12p70 and IFN? and reduction in growth of Sp2/0 and EL4 tumors by MIP are not observed in nonobese diabetic severe combined immunodeficiency mice. Overall, our study clearly demonstrates the importance of a functional immune network, in particular endogenous CD4+ and CD8+ T cells and IFN?, in mediating the anti-tumor responses by MIP.
Resumo:
A Monte Carlo model of ultrasound modulation of multiply scattered coherent light in a highly scattering media has been carried out for estimating the phase shift experienced by a photon beam on its transit through US insonified region. The phase shift is related to the tissue stiffness, thereby opening an avenue for possible breast tumor detection. When the scattering centers in the tissue medium is exposed to a deterministic forcing with the help of a focused ultrasound (US) beam, due to the fact that US-induced oscillation is almost along particular direction, the direction defined by the transducer axis, the scattering events increase, thereby increasing the phase shift experienced by light that traverses through the medium. The phase shift is found to increase with increase in anisotropy g of the medium. However, as the size of the focused region which is the region of interest (ROI) increases, a large number of scattering events take place within the ROI, the ensemble average of the phase shift (Delta phi) becomes very close to zero. The phase of the individual photon is randomly distributed over 2 pi when the scattered photon path crosses a large number of ultrasound wavelengths in the focused region. This is true at high ultrasound frequency (1 MHz) when mean free path length of photon l(s) is comparable to wavelength of US beam. However, at much lower US frequencies (100 Hz), the wavelength of sound is orders of magnitude larger than l(s), and with a high value of g (g 0.9), there is a distinct measurable phase difference for the photon that traverses through the insonified region. Experiments are carried out for validation of simulation results.
Resumo:
Background: Levamisole, an imidazo(2,1-b) thiazole derivative, has been reported to be a potential antitumor agent. In the present study, we have investigated the mechanism of action of one of the recently identified analogues, 4a (2-benzyl-6-(4'-fluorophenyl)-5-thiocyanato-imidazo2,1-b]1,3,4]thi adiazole). Materials and Methods: ROS production and expression of various apoptotic proteins were measured following 4a treatment in leukemia cell lines. Tumor animal models were used to evaluate the effect of 4a in comparison with Levamisole on progression of breast adenocarcinoma and survival. Immunohistochemistry and western blotting studies were performed to understand the mechanism of 4a action both ex vivo and in vivo. Results: We have determined the IC50 value of 4a in many leukemic and breast cancer cell lines and found CEM cells most sensitive (IC50 5 mu M). Results showed that 4a treatment leads to the accumulation of ROS. Western blot analysis showed upregulation of pro-apoptotic proteins t-BID and BAX, upon treatment with 4a. Besides, dose-dependent activation of p53 along with FAS, FAS-L, and cleavage of CASPASE-8 suggest that it induces death receptor mediated apoptotic pathway in CEM cells. More importantly, we observed a reduction in tumor growth and significant increase in survival upon oral administration of 4a (20 mg/kg, six doses) in mice. In comparison, 4a was found to be more potent than its parental analogue Levamisole based on both ex vivo and in vivo studies. Further, immunohistochemistry and western blotting studies indicate that 4a treatment led to abrogation of tumor cell proliferation and activation of apoptosis by the extrinsic pathway even in animal models. Conclusion: Thus, our results suggest that 4a could be used as a potent chemotherapeutic agent.
Resumo:
A novel approach that can more effectively use the structural information provided by the traditional imaging modalities in multimodal diffuse optical tomographic imaging is introduced. This approach is based on a prior image-constrained-l(1) minimization scheme and has been motivated by the recent progress in the sparse image reconstruction techniques. It is shown that the proposed framework is more effective in terms of localizing the tumor region and recovering the optical property values both in numerical and gelatin phantom cases compared to the traditional methods that use structural information. (C) 2012 Optical Society of America
Resumo:
Background: The consumption of berry fruits, including strawberries, has been suggested to have beneficial effects against oxidative stress mediated diseases. Berries contain multiple phenolic compounds and secondary metabolites that contribute to their biological properties. Methodology/Principal Findings: Current study investigates the anticancer activity of the methanolic extract of strawberry (MESB) fruits in leukaemia (CEM) and breast cancer (T47D) cell lines ex vivo, and its cancer therapeutic and chemopreventive potential in mice models. Results of MTT, trypan blue and LDH assays suggested that MESB can induce cytotoxicity in cancer cells, irrespective of origin, in a concentration-and time-dependent manner. Treatment of mice bearing breast adenocarcinoma with MESB blocked the proliferation of tumor cells in a time-dependent manner and resulted in extended life span. Histological and immunohistochemical studies suggest that MESB treatment affected tumor cell proliferation by activating apoptosis and did not result in any side effects. Finally, we show that MESB can induce intrinsic pathway of apoptosis by activating p73 in breast cancer cells, when tumor suppressor gene p53 is mutated. Conclusions/Significance: The present study reveals that strawberry fruits possess both cancer preventive and therapeutic values and we discuss the mechanism by which it is achieved.