The rapid identification of mycobacterial DNA in clinical samples by PCR can be useful in the diagnosis of tuberculous infections, but several large studies have found that the sensitivity of this approach is not better than that of culture. In order to improve the sensitivity of detection of mycobacterial DNA in clinical specimens from patients with paucibacillary forms of tuberculosis, we have developed a procedure permitting the specific capture of mycobacterial DNA in crude samples prior to amplification, thereby concentrating the target sequences and removing irrelevant DNA and other potential inhibitors of the amplification reaction (sequence capture-PCR). By using this approach to capture and amplify two different sequences specific for organisms of the Mycobacterium tuberculosis complex (IS6110 and the direct repeat region), it was possible to detect as little as one genome of mycobacterial DNA in samples containing up to 750 micrograms of total DNA, representing a 10- to 100-fold increase in sensitivity compared with that obtained by purifying total DNA prior to amplification. Detection of the IS6110 sequence in pleural fluid samples from patients with tuberculous pleurisy by sequence capture-PCR gave positive results in 13 of 17 cases, including 3 of 3 culture-positive samples and 10 of 14 culture-negative samples. In contrast, when total DNA was purified from these samples by adsorption to a silica matrix prior to amplification, only the three culture-positive samples were positive by PCR. The sensitivity of detection of the direct repeat sequence in these samples by sequence capture-PCR was similar to that of IS6110 and, in addition, permitted immediate typing of the strains from some patients. We conclude that sequence capture-PCR improves the sensitivity of detection of mycobacterial DNA in paucibacillary samples. This approach should be useful in detecting rare target sequences from organisms implicated in other pathologic processes. 相似文献
Techniques which are currently used to measure skeletal muscle blood flow (SMBF) in patients with congestive heart failure (CHF) are neither convenient nor accurate. They have led to discrepant results in patients with congestive heart failure and are, in part, responsible for the ongoing debate regarding the factors which limit the rise in body oxygen consumption during exercise in these patients. However, direct measurement of SMBF may not be needed during exercise in patients with severe CHF. Their skeletal muscles maximally extract oxygen. Consequently, increase in oxygen consumption by the skeletal muscles is only mediated by a concomitant increase in SMBF. In patients with severe CHF, peak body oxygen consumption attained during maximal exercise closely depends on the rise in SMBF, and thus provides an indirect measurement of SMBF. 相似文献
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