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1.
Recombinant antibody fragments can be produced in large quantities using bacterial expression systems and could potentially be useful for the generation of biofilters for the selective removal of viral particles from fluids. A human single chain-Fv antibody library, derived from synthetic repertoires of germ line VH-gene segments rearranged in vitro and paired to a single light chain (Nissim et al., 1994, EMBO J., 13, 692-698), has recently been used to isolate hundreds of different binding specificities by panning with antigen. Antibodies from this library typically have affinities in the 10(6)-10(7) M-1 range. Occasionally, better binders are isolated but at other times the affinities recovered are poor. In the latter situation binding cannot be detected with soluble antibodies, but only by high-avidity display of multiple copies of antibodies on phage. By panning with human cytomegalovirus (HCMV)-coated immunotubes, we have isolated a number of antibody clones from this library that bound to the antigen only if displayed on the filamentous phage, but not in soluble form. One of these clones was selected for an affinity maturation procedure, achieved by combinatorial mutagenesis of the complementarity determining region 3 (CDR3) of the antibody light chain, followed by selection of the resulting library for HCMV binding. By this means, we were able to isolate a number of binders, some of which exhibited specific HCMV binding in soluble form. The clone that gave the strongest ELISA signal was expressed in bacteria, purified in solution, characterised using a novel capture methodology with surface plasmon resonance detection on a BIAcore instrument and used for the production of an immunofilter for the removal of HCMV form human serum. The filter removed more than 99% of applied HCMV in 10 min circulation time, while the amount of HCMV retained non-specifically in a cartridge derivatised with a non-specific antibody was less than 10% under similar conditions.  相似文献   
2.
The effect of the internal Rayleigh scattering on the gain efficiency and noise of the erbium-doped fiber amplifier has been considered in detail. It is shown that excess background loss due to Rayleigh scattering at the signal and pump wavelengths dramatically reduces the optimum gain efficiency of either high NA, low-concentration or confined-dopant erbium-doped fibers. Distributed feedback due to Rayleigh backscattering, on the other hand, degrades the noise performance of high gain amplifiers considerably. In applications where high gain and low noise figure are required, increasing the fiber NA and dopant confinement above an optimum value are shown to increase the required pump power dramatically due to the deleterious effects of Rayleigh backscattering  相似文献   
3.
提出一种采用空间级联可调谐光滤波器方式实现的OADM.该器件不但具有集成度高、体积小、插入损耗低、信道间插入损耗差异小的特点,而且能够在控制电路的作用下灵活选择上下路波长及其数量,为构建灵活、高性能的WDM网络提供了选择.  相似文献   
4.
A noise figure of 2.9±0.4 dB, measured in a high-gain erbium-doped fiber amplifier for input signals in the range -35 to -15 dBm and for pump powers of >5.8 mW, is discussed. The spontaneous emission factor nsp was 0.99±0.09 for input signals less than -15 dBm. These low figures are attributable to the optimized fiber design and the use of a pump wavelength of 980 nm, at which erbium operates as a true three-level system. These two factors contribute to the very low (~500 μW) pump threshold seen in fiber, which permits nearly complete inversion to be achieved for the low pump powers employed  相似文献   
5.
为达到某移动通信系统对漏泄同轴电缆主要电气指标的要求,设计一种U形漏泄同轴电缆,以满足工程应用。阐述了漏泄同轴电缆耦合损耗和传输衰减两个重要电气指标,以U形漏泄同轴电缆实例,利用三维电磁仿真软件HFSS仿真分析900 MHz工作频率下节距及槽孔尺寸的变化对耦合损耗、传输衰减的影响,仿真结果与实测结果吻合良好。结果表明U形漏泄同轴电缆节距越小,漏泄同轴电缆耦合损耗越小。  相似文献   
6.
The efficacy and tolerability of aminoglutethimide for the treatment of Cushing's syndrome was assessed in 66 cases three of which are described in the present paper. Aminoglutethimide provided palliation from the signs and symptoms of hypercorticism in 13 of 21 patients with metastatic adrenocortical carcinoma and four of six patients with ectopic ACTH production due to metastatic carcinomas. All six of the patients with adrenal adenomas showed clinical and biochemical improvement, while 14 of the 33 patients with bilateral adrenal hyperplasia of pituitary origin improved. Adverse reactions attributed to aminoglutethimide such as drowsiness, rash, and nausea occurred in 58 per cent of cases. These data suggest that aminoglutethimide has a place in controlling the signs and symptoms of adrenocorticoid excess in patients with Cushing's syndrome due to malignancy and is effective preoperative therapy for patients with adrenal adenomas and bilateral hyperplasia.  相似文献   
7.
During a five year period, idiopathic hypertrophic subaortic stenosis was diagnosed in nine patients 70 to 79 years of age and in 26 patients 20 to 66 years of age who were referred to the cardiology division of the Long Island Jewish-Hillside Medical Center because of symptomatic heart disease. Only one of the older patients, compared with 19 of the younger ones, was referred with the correct diagnosis. Coronary artery disease with papillary muscle dysfunction was incorrectly diagnosed in four of the older patients. Cardiac catheterization confirmed the diagnosis of idiopathic hypertrophic subaortic stenosis in all of the 26 younger patients and in five of the nine older ones; diagnosis was based on typical echocardiographic features in the other four patients. Symptoms, physical findings, and electrocardiographic observations were similar in both groups. Aortic valve calcification was found in one younger patient and three older ones. The ratio of women to men was higher in the older group (7:2) than in the younger group (12:14). Coronary artery disease was more frequent in the older patients (three of five, compared with six of 26). Our experience indicates that idiopathic hypertrophic subaortic stenosis is not rare during the eighth decade. The diagnosis should be considered in any patient with an unexplained appropriate heart murmur, and definitive studies, such as echocardiography, should be done. As with any condition, proper management depends on accurate diagnosis.  相似文献   
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The expression of membrane immunoglobulin (mIg) was examined in three cloned MPC11-derived mouse myeloma cell lines. Membrane immunofluorescence studies demonstrated that IgG2b producer cells (P1) had complete IgG molecules, L-chain producer (L1) had only L-chain determinants and nonproducer (NP2) did not have any Ig determinants on the cell surface. An Ig receptor, with characteristics different from B lymphocyte Fc receptor, has been found to be present on secreting cells (P1 or L1), but not on the NP2 cell variant. The data reported in the present paper indicate that the expression of mIg and of the Ig receptor molecule is clearly correlated with the process of secretion. In the light of previous data reported on Ig secretion, a model is proposed which correlates the process of secretion with the expression not only of mIg, but also of the receptor for Ig.  相似文献   
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