The intracellular distribution of the anthracyclinic antibiotic adriamycin in living cultured cells has been investigated by confocal microscopy. In human melanoma cells (M14), adriamycin was localized inside the nuclei. When adriamycin-treated M14 cells were allowed to recover in drug-free medium, a complete efflux of the drug from the nucleus was revealed. In recovered cells, a weakly fluorescent signal was observed in the perinuclear region. When M14 cells were recovered in a medium containing colcemid, a microtubule depolymerizing agent, the drug transport from the nucleus to the cell periphery appeared to be inhibited, suggesting that the microtubule network is strongly involved in drug transport mechanisms. In multidrug-resistant (MDR) cells the intracellular location of adriamycin was shown to be noticeably different from that of the parental wild-type cells. In particular, in resistant human breast carcinoma cells (MCF-7), adriamycin appeared to be exclusively located within the cytoplasm whereas the nuclei were shown to be completely negative. When adriamycin treatment was performed in association with MDR revertants, such as Lonidamine (inhibitor of the energy metabolism) or verapamil (inhibitor of the P-glycoprotein efflux pump), a marked enhancement of the cytoplasmic signal was observed in resistant cells. Under these conditions, adriamycin appeared concentrated in the perinuclear region, but the nuclei were still negative. Confocal microscopy proved to be a very useful method for the study of the intracellular transport of fluorescent substances, such as anthracyclinic antibiotics, and for the investigation of the multidrug resistance phenomenon in tumour cells. 相似文献
The authors describe 5 cases, 3 boys and 2 girls, with idiopathic growth hormone deficiency in prepubertal age, treated with human growth hormone. In four of five cases the response to treatment with GH was relevant. Only in one case (F1) the response was negative. The results of this study confirm that rhGH is a safe and effective therapy in children with GHD. 相似文献
A new practical design approach for minimum-phase FIR or IIR filters, setting out from a high dimensionality FIR linear-phase prototype is described. The novelty of this technique lies in overcoming the inherent problem of finding the roots of a high order polynomial with repeated and/or very closely clustered roots 相似文献
Comparisons of various energy systems are often made from partial, limited standpoints that do not take into due consideration the numerous factors involved in such systems. A more complete assessment of the global quality of energy systems must consider a wider range of characteristics, such as: conversion and transportation yields, energy potential, added value, risk of accidents during conversion and transportation, coefficients of transportability and storability, and polluting emissions (carbon monoxide, carbon dioxide, sulphur and nitrogen oxides, unburnt hydrocarbons, dust, radionuclides and dispersed heat).
This paper not only identifies and quantifies the parameters that allow the above qualities to be expressed, but also defines a tree-structured energy-quality index system which starts from the parameters identified and makes it possible to obtain a global summary index, through various intermediate levels of aggregation.
Our objective is to make an instrument available to professionals (engineers, policymakers and energy managers) which allows them to concentrate their attention each time, according to the specific needs in question, on particular aspects of the quality of the energy, or to obtain numerical indicators that briefly express quality in the broadest sense.
In addition, a sample application of the proposed method is presented, using data gathered mainly from the literature on alternative systems for power production and space heating by fossil fuels. 相似文献
This paper deals with a new application of the time-domain windowed (smoothed version) of the pseudo Wigner-Ville distribution (PWD), that can be easily implemented in a dedicate digital instrument to be used as a spectral analyzer for time-frequency analysis of nonstationary signals. New computational algorithms are studied and developed to attain high time-frequency resolution, accuracy, flexibility and computational efficiency. Particularly, to reduce the negative effects due to leakage during frequency changes, a new interpolation formula is derived by using the windowing theory. The suggested technique allows the users to perform optimal evaluations of the instantaneous amplitudes and frequencies of analyzed signals 相似文献
A vibrating reed magnetometer with high sensitivity is constructed. Using optical signal pickup, modified excitation coils, and an acoustical reference excitation system, the high sensitivity of former constructions is combined with the detection of the magnetization component perpendicular to the bias field H. The calibration procedure providing increased reliability is simplified and allows hysteresis measurements with the magnetic easy axis of the sample oriented at an arbitrary angle with respect to H. Measurement results are given in order to demonstrate the performance of the apparatus 相似文献
Summary The synthesis of new high optical abrasion resistance coating materials has been undertaken by functionalizing melamine and
tris(m-aminophenyl)phosphine oxide with a triethoxysilane containing reagent. These highly functionalized compounds have been
used for coating a bis-phenol-A polycarbonate substrate by the sol-gel method. Preliminary data shows the abrasion resistance
of the polymer substrate is considerably improved when it is coated by these optically clear materials. 相似文献
Many current implementations of protocols such as the Transmission Control Protocol/Internet Protocol (TCP/IP) are inefficient because data are often accessed more frequently than necessary. Three techniques that reduce the need for memory bandwidth are proposed. The techniques are copy-on-write, page remapping, and single-copy. Afterburner, a network-independent card that provides the services that are necessary for a single-copy protocol stack, is described. The card has 1 MByte of local buffers and provides a simple interface to a variety of network link adapters, including HIPPI and asynchronous transfer mode (ATM). Afterburner can support transfers to and from the link adapter card at rates up to 1 Gbit/s. An implementation of TCP/IP that uses the features provided by Afterburner to reduce the movement of data to a single copy is discussed. Measurements of the end-to-end performance of Afterburner and the single-copy implementation of TCP/IP are presented 相似文献