Characteristics of anthracycline-resistant strains of P388 leukemia

Two strains of P388 murine leukemia with acquired resistance to rubomycin (P388/rm) and its nitroxyl derivative ruboxyl (P388/rx). The rubomycin resistance has been developed by the 14th generation and ruboxyl one-by the 8th generation. The growth kinetic patterns and the cell cycle time of the parent and resistant strains were similar. An increased tumourogenicity of both resistant strains cells was found. The resistance development was accompanied by the appearance of the additional chromosome materials, namely of homogeneously staining region (P388/rx) and of double chromatin bodies (P388/rm). The partial recovery of sensitivity to rubomycin occurred during 36 generations (1 year). Simultaneously the genetic markers have been lost. The recovery of sensitivity to ruboxyl in this period was not observed. The obtained resistant strains possessed the multidrug resistance: the cross resistance of P388/rm and P388/rx to actinomycin D, Vinca alkaloids and colchicine was shown.     

Phosphorus-containing metabolites in the cells of anthracycline-resistant strains of leukemia P388

The method of 31P nuclear magnetic resonance has been used to study in vivo the level of phosphorus-containing metabolites in cells of two strains of murine leukemia P388 with the phenotype of the multidrug resistance and in cells of the parent strain. Cells of both resistant strains showed a depressed level of phosphomonoesters in comparison with the parent one. The influence of rubomycin and emoksil on the level of phosphorus-containing metabolites of drug-resistant and -sensitive strains has been evaluated. The drugs were established not to affect practically the pool of these metabolites of the resistant strains. Both drugs significantly increased the pool of phosphomonoesters in the parent strain cells.     

Antineoplastic activity of combinations of cytostatics and dextran-ferrite administered to mice with leukemia P-388

Water solutions of adriblastin, dactinomycin, rosevin, methotrexate, cisplatin, sarcolysine, rubomycin, cyclophosphamide, 5-fluorouracil or ftorafur were combined with dextran ferrite. The obtained compositions were injected i.p. to BDF1 mice 24 hours after they were inoculated with one million of murine P388 leukemic cells. Antitumor activity was fully retained for each of these agents in combination with dextran ferrite.     

Gene amplification and rearrangement of murine ribosomal RNA in virus-induced Rauscher leukemia

Using as a hybridization probe cDNA 35s RNA from the Rauscher leukemia cells, a part of rRNA gene cluster from the gene library of mice C-1 erythroleukemia cells has been cloned. Fragment 6.7 kb recloned into pUC19 rRNA was used as a probe to analyse organization of rRNA genes of mice with RL. The observed amplification and rearrangement in genome DNA of spleen cells are determined by a new type of their rRNA genes rearrangement in the nontranscribed as well as in the transcribed part of rRNA.     

Effects of intracellular Na+/K+ ratio on histone gene expression in ascitic cells of leukemia P-388 and Ehrlich cancer

The intracellular Na+/K+ ratio was studied for its effect on histone genes expression in Ehrlich carcinoma and leukemia P-388 ascites cells. After equilibration with certain Na+/K+ ratio buffers at 0-4 degrees C the cells were treated during 1 h at 37 degrees C with ouabain added to the corresponding medium. Then total RNAs were extracted and analyzed by the reaction of blot-hybridization with histone genes cluster in plasmid p604. The maximal level of histone genes expression in leukemia P-388 cells was observed under conditions when intracellular Na+/K+ ratio corresponded to those at S-phase of the mitotic cycle. In Ehrlich carcinoma ascites cells the expression of histone genes was not dependent on the Na+/K+ ratio. A conclusion is drawn that the intracellular ratio of monovalent cations is one of the possible mechanisms which regulates the gene expression during the mitotic cycle.     

Sensitivity of multiple-access techniques to narrow-bandinterference

This paper investigates the sensitivity of several multiple-access techniques to narrow-band interference. The analysis covers time-division multiple access (TDMA), code-division multiple access (CDMA), and orthogonal frequency-division multiple access (OFDMA). The study is carried out under the assumption that all the considered multiple-access systems occupy the same total bandwidth, and the bit rates of all active users are identical. A major finding of this study is that CDMA with pseudonoise spreading sequences is more sensitive to narrow-band interference than TDMA. We point out that the signal-to-jammer power ratio at the decision device input is in fact identical for both multiple-access techniques, but the amplitude distribution of the jammer term at the threshold detector input is more favorable to TDMA, which turns out to be more robust in terms of bit-error rate. Another finding is that in terms of sensitivity to narrow-band interference, orthogonal CDMA (OCDMA) is closer to TDMA than to CDMA with pseudonoise sequences, because the degradation is not the same for all users. Finally, we discuss the relationship of OCDMA and TDMA and highlight the superiority, in terms of capacity over the narrow-band interference channel, of TDMA to the other multiple-access techniques considered in this paper     

P2P对FTTH的影响

文章对点对点( Peer-to-Peer,P2P)技术和光纤到户(FTTH)的概念进行了简单描述.重点对P2P的应用、P2P应用的带宽需求、P2P在IP网络电视(IPTV)中的应用特点进行了分析.最后得出了这样一个结论,P2P的应用不可阻挡,FTTH的普及也是不可阻挡的.     

Sensitivity of dielectric resonators to environmental conditions

The effects of the variation of different physical parameters in a simple, shielded dielectric resonator structure is studied. The study uses an approximate analytical expression for the resonance frequency stability of dielectric resonators. The results are of special importance in applications where the dielectric resonators are subjected to varying environmental conditions.     

Sensitivity of metal detectors to spheroidal targets

The sensitivity of magnetic metal detectors to prolate or oblate spheroidal targets depends both on the semiaxis ratio and on the orientation of the spheroid polar axis relative to the local magnetic field. A spherical target produces null response only if the generator and detector coil magnetic fields are orthogonal, but the spheroid possesses a null direction for a large range of magnetic field orientations. A spheroid can therefore be made undetectable by rotating it into a particular orientation. The existence of such blind-position angles is investigated theoretically in detail and families of curves are given to illustrate them in a particular case     

GaAs MESFET的压力敏感特性

本文研究了ＧａＡｓ ＭＥＳＦＥＴ对应力的敏感特性，分析了敏感原理。对ＧａＡｓ ＭＥＳＦＥＴ用作力学量传感器的可能性进行了讨论。     

Effects of intracellular Na+/K+ ratio on expression of c-fos oncogene and beta-actin gene in ascitic cells of leukemia P-388 and Ehrlich tumor

The intracellular Na+/K+ ratio was studied for its effect on expression gene beta-actin and oncogene c-fos and activity of these genes during the mitotic cycle in ascites cells of leukemia P-388 and Ehrlich tumour. It was established that gene beta-actin was activated at high and low ratios of Na+/K+, while c-fos only at high ones. The expression of these genes during the mitotic cell cycle was due to changes in the intracellular Na+/K+ ratio. The obtained data showed an important role of intracellular homeostasis of monovalent cations in regulation of gene expression during the mitotic cell cycle.     

Sensitivity of double-gate and FinFETDevices to process variations

We investigate the manufacturability of 20-nm double-gate and FinFET devices in integrated circuits by projecting process tolerances. Two important factors affecting the sensitivity of device electrical parameters to physical variations were quantitatively considered. The quantum effect was computed using the density gradient method and the sensitivity of threshold voltage to random dopant fluctuation was studied by Monte Carlo simulation. Our results show the 3/spl sigma/ value of V/sub T/ variation caused by discrete impurity fluctuation can be greater than 100%. Thus, engineering the work function of gate materials and maintaining a nearly intrinsic channel is more desirable. Based on a design with an intrinsic channel and ideal gate work function, we analyzed the sensitivity of device electrical parameters to several important physical fluctuations such as the variations in gate length, body thickness, and gate dielectric thickness. We found that quantum effects have great impact on the performance of devices. As a result, the device electrical behavior is sensitive to small variations of body thickness. The effect dominates over the effects produced by other physical fluctuations. To achieve a relative variation of electrical parameters comparable to present practice in industry, we face a challenge of fin width control (less than /spl sim/1 nm 3/spl sigma/ value of variation) for the 20-nm FinFET devices. The constraint of the gate length variation is about 10/spl sim/15%. We estimate a tolerance of 1/spl sim/2 /spl Aring/ 3/spl sigma/ value of oxide thickness variation and up to 30% front-back oxide thickness mismatch.     

Sensitivity of phase-conjugate resonators to intracavity phase perturbations

The sensitivity of phase-conjugate resonators to phase perturbations is analyzed numerically. It is shown that as long as the phase-conjugate mirror (PCM) intercepts most of the light traveling towards it, this type of resonator provides much improvement over conventional optical cavities.     

Sensitivity of PSK Modulation Techniques to Nonlinear Distortions

A model of a PSK transmitter including the modulator, a filter, and a nonlinear amplifier is considered. The envelope fluctuations of the filtered signal and the spectral spreading effect, resulting from nonlinear distortion are analyzed, considering three PSK modulation techniques: conventional four-phase PSK (Q-PSK), offset PSK(OPSK) and logic-PSK(L-PSK). The last technique exhibits the smallest envelope fluctuations and the lowest sidelobe levels after nonlinear distortion, particularly when the nonlinear element operates near saturation.     

Sensitivity of microstrip antennas to admittance boundary variations

The analysis of microstrip antennas is greatly simplified by a technique which separates the interior fields of the antenna from its exterior fields through the application of an admittance boundary condition at the periphery of the antenna. The goal of this investigation is to determine the accuracy to which one must obtain this "wall" admittance in order to predict operating parameters to a specified tolerance. For a typical microstrip antenna the "wall" admittance must be known to within 4 percent to predict the operating frequency to 0.5 percent.     

Sensitivity of grating-coupled surface emitters to length-inducedphase variations

The longitudinal mode structure of a two-gain section, three-grating surface emitting laser is studied as a function of length-induced phase variations. It is found that several mode hops occur in the course of changing the length of one of the gain sections by one grating period. Although the number of mode hops can be reduced by optimizing the design, stable, single-mode laser operation appears to require control of the optical length of each gain and grating section to better than one wavelength     

Sensitivity of insulator-semiconductor structures to time-dependent light fluxes

The kinetics of the electronic processes in metal-insulator-semiconductor structures in which the insulator layer has low conductivity is considered. When a dc bias voltage is applied to such a structure, a nonequilibrium depletion region appears in the semiconductor layer. The conditions necessary for the formation of a stable depletion region and the appearance of photoelectric signals in this region are analyzed. The duration of transients and the parameters of the structure layers are estimated.     

On the Sensitivity of IMT-DS Performance to System Parameters

IMT-DS, formerly known as Universal Terrestrial Radio Access (UTRA) system,is one of five radio interface standards adopted for the third generationIMT-2000 systems. In this paper, we present results of our investigation onthe sensitivity of IMT-DS performance to variations in the system parameters.In particular, the performance of a multi-rate IMT-DS system is investigatedfor different Rake structures, interleaving depths, and Doppler frequencies.An approximate expression for the bit error rate (BER) of a Rake receivermismatched to the number of signal paths is derived. It is shown that theperformance is dependent on inter-path-interference. An improvement inperformance is obtained if antenna diversity is combined with traditionallyused path diversity in Rake receivers.