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21.
Fusion toxins are an emerging class of targeted therapeutics for the treatment of cancer. Diphtheria toxin-stem cell factor
(DT-SCF) is one such novel fusion toxin designed to target malignancies expressing c-kit. Since, c-kit overexpression has
been reported on many types of cancers, it appeared to be a reasonably good molecule to target. In the present study, we report
construction, expression, purification, and characterization of DT-SCF. DT-SCF gene coding for 1–387 amino acids of diphtheria
toxin, His-Ala linker, 2–141 amino acids of SCF was cloned into expression vector with C terminal His tag. The induced DT-SCF
protein was exclusively expressed in insoluble fraction. Purification of DT-SCF was achieved by inclusion body isolation and
metal affinity chromatography under denaturing and reducing conditions. Purified DT-SCF was renatured partially on-column
by gradually reducing denaturant concentration followed by complete refolding through rapid dilution technique. Cell viability
assay provided the evidence that DT-SCF is a potent cytotoxic agent selective to cells expressing c-kit. The novelty of this
study lies in employing SCF as a ligand in construction of fusion toxin to target wide range of malignancies expressing c-kit.
Efficacy of DT-SCF fusion toxin was demonstrated over a range of malignancies such as chronic myeloid leukemia (K562), acute
lymphoblastic leukemia (MOLT4), pancreatic carcinoma (PANC-1), and cervical carcinoma (HeLa 229). This is the first study
reporting specificity and efficacy of DT-SCF against tumor cells expressing c-kit. There was significant correlation (P = 0.007) between c-kit expression on cells and their sensitivity to DT-SCF fusion toxin. 相似文献
22.
The repulsive potential in ionic crystals recently proposed by Narayan and Ramaseshan (NR) can be expressed as the sum of the contributions from the individual ions. In the present paper we show that using this repulsive potential it is possible to divide the polarizability arising from the relative displacement of ions into its ionic constituents. NR have also derived the ionic radii in alkali halides which we have used to estimate the electronic polarizabilities of ions with the help of polarizability-radius cube relation. The electronic polarizabilities of alkali and halogen ions thus evaluated show a good agreement with those deduced from the experimental refraction data. 相似文献
23.
Mandal Prashanta Kumar Seth Gauri Shanker Sarkar Subharthi Chamkha Ali 《Journal of Thermal Analysis and Calorimetry》2021,143(3):1901-1916
Journal of Thermal Analysis and Calorimetry - Numerical simulation of a non-linear mathematical model governing an arbitrarily oblique slip flow of a nanofluid, with suspended carbon nanotubes in... 相似文献
24.
T.?L.?Shanker Rao K.?N.?Lad A.?PratapEmail author 《Journal of Thermal Analysis and Calorimetry》2004,78(3):769-774
The crystallization kinetics of amorphous Cu50Ti50 has been studied using differential scanning calorimetry (DSC) under non-isothermal conditions. The curves at different linear heating rates (2, 4, 8 and 16 K min–1) show sharp crystallization peaks. The crystallization peak shifts to higher temperatures with increasing heating rate. The Kissingers method of analysis of the shift in the transformation peak is applied to evaluate the activation energy (E
c). The KJMA formalism, which is basically developed for isothermal experiments, is also used to obtain E
c and the Avrami parameter (n).The DSC data have been analysed in terms of kinetic parameters, viz. activation energy (E
c), Avrami exponent (n) and frequency factor K
0 using three different theoretical models. It is observed that the activation energy values derived from KJMA approach and modified Kissinger equation agree fairly well with each other. The activation energy values obtained from normal Kissinger method, and Gao and Wang expression underestimate the activation energy.The financial support provided by All India Council for Technical Education (AICTE), New Delhi (Govt. of India) is gratefully acknowledged. 相似文献
25.
Balasubramaniam Shanker 《International Journal of Infrared and Millimeter Waves》1993,14(5):1077-1081
A simple derivation of the Green's functions for Beltrami fields is presented for use with time-harmonic electromagnetism in homogeneous biisotropic media. 相似文献
26.
M.J. Singh S.K. Goel R. Shanker D.O. Kataria N. Madhavan P. Sugathan J.J. Das D.K. Avasthi A.K. Sinha 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,4(1):7-13
Measurements were carried out to deduce the transverse kinetic energies of highly charged argon recoil ions produced in single
collisions of 120 MeV ions with argon atoms in which the post collision charge states of the projectiles were not determined. A time of flight
spectrometer was designed and fabricated to detect the charge states of recoils. Experimental procedures for optimizing the
spectrometer for extraction, transmission and detection of recoils are described. A simple approach for determining the transverse
kinetic energy of the recoil ions from FWHM of the peaks is reported. This method is shown to be independent of the choice
of collision partners and requires only the knowledge of the physical values of “optimized parameters” of time-of-flight spectrometer
used in the experiment. The transverse kinetic energy of the recoil ions determined from the present approach is found to
vary from 0.03 eV for to 4.02 eV for Ar10+. These values are compared with the results reported by earlier workers and are shown to follow a q2-behaviour up to a charge state q
=8+ of the recoil ions.
Received: 5 February 1998 / Revised: 8 June 1998 / Accepted: 11 June 1998 相似文献
27.
28.
Summary The pH of an aqueous solution of Gum Dhawa (Anogeissus latifoliaWall.) is 2.68 and it is sensitive to pH changes. The absence of the sulphate and the presence of a slight trace of phosphate, confirms the view that the acidity is due to the presence of carboxyl groups, which are formed by the hydrolysis of the gum. The hydrogen ion activity increases up to a concentration of 3% and beyond this point it attains a steady value. The sp. cond. is zero at the zero concentration and the relation between sp. cond. and up to 3% concentration is linear and afterwards it attains a steady value. It has been found by experimental observation that the gum solution has got no buffering capacity. Neutralization curves with NaOH and Ba(OH)2 show that the combination with alkali takes place in equivalent proportion. The viscosity of the gum solution always increases with increasing pH on the addition of HCl. The viscosity increase with NaOH is slow in the beginning, but after pH 4.2 it rises rapidly, attains a maximum and steeply falls off near pH 6.7. Now it decreases slowly and again a deviation is noted at 10.5. The viscosity is maximum near about the neutralization point. This is due to the stretched chain of the polymer unit. The fall in viscosity is explained by the folding chain theory in conjunction with mass action or common ion effect and due to the destruction of the proteins, by concentrated NaOH, which forms a complex with carbohydrate polymer.The authors wish to thank Dr.R. C. Mehrotra, Professor and the Head of the Chemistry Department, for providing all facilities for this work. Our thanks are also due to the Ministry of Education, Government of India, for the award of a research scholarship to one of us (V.K.S.). 相似文献
29.
30.
It has been a general opinion that the Clausius-Mossotti dielectric theory is not capable of explaining the observed photoelastic behaviour of partially ionic crystals.However in the present communication we show that by making account of the variation of polarizabilities under compressive stress within the framework of the Clausius-Mossotti theory it is possible to obtain a reasonable agreement with experimental data on the photoelastic behaviour of ZnO, ZnS and CdS crystals. 相似文献