A proposed system whereby a (colcemid-induced) S2 phase is responsible for the tetraploidy found in cultured human amniotic fluid cells

The results of this study, using cultured amniotic fluid cells (AFC) and colcemid, together with results of several other investigators who worked with colcemid and DNA synthesis, have led to the proposal of a hypothesis suggesting a mechanism by which tetraploidy may be induced. Data from this study of 24,455 mitotic spreads indicate increased concentrations of colcemid, as well as extended exposure times, results in a higher incidence of tetraploidy in cultured AFC, with no concomitant increase in the unexposed control cells.     

Computed tomographic angiography of the thoracic vessels: the method, initial experience and outlook for its use

The paper presents the data available in the literature on computed tomographic angiography and the first experience with it to study thoracic vessels. It details the principles of spiral computed tomography and CT angiography. Practical aspects of their implementation, as well as basic concepts are outlined. It is concluded that CT angiography is promising in studying thoracic vessels in various abnormalities.     

Hernia development in CAPD patients and the effect of 2.5 l dialysate volume in selected patients

Merkel cell carcinoma (MCC) of the skin is a rare, primary malignant skin neoplasm which can present as a cutaneous nodule. These neoplasms are seen primarily in the elderly and located in the head and neck area or extremities. Twenty-nine aspirates from primary and metastatic lesions obtained by percutaneous fine-needle aspiration in 19 patients have been studied. The cytomorphologic features, clinical information, and immunocytochemical (ICC) findings are detailed. Aspirate smears demonstrated small-to-intermediate-sized cells with a loosely cohesive pattern. Nuclei were round with finely granular chromatin and multiple, small nucleoli. Cells possessed a thin rim of cytoplasm, and infrequent pseudorosette formations were noted in cell groups. ICC results were universally positive for cytokeratin, which showed a paranuclear "dot-like" pattern. Neuron-specific enolase, epithelial membrane antigen, and S-100 protein were positive in varying degrees. Leukocyte common antigen was universally negative. The diagnosis of MCC of the skin by FNA can be made by applying cytologic features in addition to ancillary studies and clinical information.     

Identification of Two Sex Pheromone Components of the Potato Aphid, Macrosiphum euphorbiae (Thomas)

Females of the potato aphid Macrosiphum euphorbiae exhibit typical calling behavior, with virgin female oviparae raising their back legs off the substrate to release sex pheromone from glands on the tibia. Airborne collections from calling oviparae were analyzed by GC and GC-MS to determine if, like the majority of aphids examined to date, they produced (1R,4aS,7S,7aR)-nepetalactol (1) and (4aS,7S,7aR)-nepetalactone (2). Both components were present and produced in ratios that varied with age from 4:1 to 2:1. The relative stereochemical configurations of these components were determined by GC-coinjection of the aphid-derived sample with synthetic standards on both HP-1 and DB-Wax GC columns. The absolute stereochemical configuration of the nepetalactol (determined from approximately 15 microg of material in an air entrainment sample) was determined as (1R,4aS,7S,7aR)-1 by derivatization of the aphid sample with (S)-(+)-alpha-methoxy-alpha-(trifluoromethyl)phenylacetyl chloride (Mosher's acid chloride) to generate a diastereoisomer that was compared to synthetic samples by NMR spectroscopy and GC. In bioassays in the wind tunnel, M. euphorbiae males responded to potato plants with oviparae but not to unattacked plants or those infested with parthenogenetically reproducing apterae. In no-choice laboratory bioassays, the same level of male response was observed to virgins and to the 3:1-5:1 synthetic blends of nepetalactol (1):nepetalactone (2). However, the time taken to reach the source was significantly less to virgin females than to the synthetic pheromone blends. In all cases, males walked rather than flew to the source. Males showed lower responses to a 1:1 synthetic mixture and did not respond to either of the components when presented alone. Under field conditions, few M. euphorbiae males were captured in traps baited with different ratios of the synthetic pheromone. Possible reasons for the different responses under laboratory and field conditions are discussed.     

Dual polymer bonding of thermoplastic composite structures

This paper describes a process that facilitates fusion bonding of thermoplastic composite components without the need for complex fixtures and without disrupting the fiber alignment in the component laminates. The dual polymer bonding process, Thermabond, requires that an interlayer polymer be fused to the surface of each laminate prior to bonding. The characteristics of the interlayer polymer allow for joining of the components at a temperature below the softening/melting point of the reinforced polymer in the composite laminates. This leads to significant processing advantages without significant loss in mechanical performance. Discussions of resin compatibility, the effect of process conditions on mechanical performance, and the application of the APC-2/PEI Thermabond system to various structural components are included.     

Epidermal growth factor (EGF) receptor blockade inhibits the action of EGF, insulin-like growth factor I, and a protein kinase A activator on the mitogen-activated protein kinase pathway in prostate cancer cell lines

For assays involving glycosyltransferases or transporters, several GDP-sugars are either commercially unavailable or expensive. We describe an enzymatic synthesis of GDP-d-[3H]arabinosep and GDP-l-[3H]fucose that yields 66-95% nucleotide-sugar from the appropriate radiolabeled sugar in less than 30 min. The coupled reaction requires Mg2+, ATP, and GTP along with the appropriate radioactive monosaccharide, sugar-1-kinase, and pyrophosphorylase. The latter two activities are present in a cytosolic fraction of Crithidia fasciculata, which is easily grown at room temperature in simple culture medium without serum or added CO2. Addition of commercial yeast inorganic pyrophosphatase shifts the equilibrium of the pyrophosphorylase reaction toward nucleotide-sugar formation. To verify that these nucleotide-sugars are biologically active, we tested their ability to serve as substrates for glycosyltransferases. GDP-l-[3H]fucose functions as the donor substrate for recombinant human fucosyltransferase V, and GDP-d-[3H]arabinosep serves as the donor substrate for the arabinosyltransferase activities present in Leishmania major microsomes.     

执行器失效不确定时滞系统的指定衰减度鲁棒可靠控制

针对一类含有时变时滞的不确定参数线性系统,研究了在执行器发生故障情况下的鲁棒可靠控制器设计问题.系统中的参数不确定性满足广义匹配条件,时变时滞的大小及其变化率有界,并假设故障执行器元件的输出为零.经过适当的模型变换,将原系统的鲁棒指数镇定问题转化为另一个等价系统的鲁棒镇定问题.根据Lyapunov稳定性理论和线性矩阵不等式(LMI)方法,分别给出了鲁棒可靠控制器存在的时滞无关和时滞相关充分条件.仿真结果表明了该控制器设计方法的有效性.