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排序方式: 共有114条查询结果,搜索用时 421 毫秒
1.
The effects of the trichothecene mycotoxins (acetyl T-2 toxin, T-2 toxin, HT-2 toxin, palmityl T-2 toxin, diacetoxyscirpenol (DAS), deoxynivalenol (DON), and T-2 tetraol) on bovine platelet function were examined in homologous plasma stimulated with platelet activating factor (PAF). The mycotoxins inhibited platelet function with the following order of potency: acetyl T-2 toxin > palmityl T-2 toxin = DAS > HT-2 toxin = T-2 toxin. While T-2 tetraol was completely ineffective as an inhibitor, DON exhibited minimal inhibitory activity at concentrations above 10×10?4M. The stability of the platelet aggregates formed was significantly reduced in all mycotoxin treated platelets compared to that of the untreated PAF controls. It is suggested that the increased sensitivity of PAF stimulated bovine platelets to the more lipophilic mycotoxins may be related to their more efficient partitioning into the platelet membrane compared to the more hydrophilic compounds. 相似文献
2.
During the past 10 years, epidemics of black spots on the scalps of schoolchildren have caused considerable concern in at least 4 communities in the Rocky Mountain states. We describe the clinical presentation of "black spots" in a group of Wyoming elementary school students and the epidemiologic investigation that revealed the cause. Our study included a questionnaire survey of students'' parents, examination of students at the affected school and at two other schools, observation of playground activity patterns, and laboratory analysis of specimens taken from affected children and from the school environment. The black material in the scalp spots was chemically identical to flakes of black material found on the playground and tar from the school roof. We concluded that the spots were caused by flakes of windblown tar from the school roof. Previous outbreaks of black spots may have had a similar cause. 相似文献
3.
Active and passive cation transport and L antigen hertogeneity in low potassium sheep red cells 下载免费PDF全文
Several lines of experimental evidence are presented suggesting that the L antigens in low potassium (LK) sheep red cells are associated with separate Na(+)K(+) pump flux is distinct from the action of anti-L(l) on K(+) leak flux, implying that K(+) leak transport sites may not be converted into active pumps by the L antiserum. Treatment of LK red cells with trypsin completely abolished both the stimulation of K(+) pump flux and the enhancement of the rate of ouabain binding brought about by anti- L. That this effect is due to a total destruction of the L(p) determinant associated with the LK pump was evident from the complete failure of anti-L(p) to bind to trypsinized LK red cells. The L(p) antigen can be effectively protected against the trypsin attack by prior incubation with anti-L, indicating that the sites for antibody binding and trypsin action may be closely adjacent at the structural level. Trypsin treatment, however, did not interfere with anti-L(l) reducing ouabain insensitive K(+) leak influx, nor did it prevent binding of anti-L(ly), the hemolytically active L antibody which is probably identical with anti-L(l). The functional independence of the L(p) and L(l) sites was documented by the observation that anti-L(l) still reduced K(+) leak influx in LK cells with experimentally induced high potassium concentrations, at which K(+) pump flux is fully suppressed, whether or not anti-L(p) was binding to the L(p) antigen associated with the LK pump. 相似文献
4.
A 15-year-old patient with ITP which was refractory to corticosteroids, splenectomy, and immunosuppressive therapy with vincristine was twice treated with platelets loaded with vinblastine. Five days after the application of the platelets vinblastine complex the platelets began to rise up to 600 X 10(9)/l. The remission has lasted until now for more than 15 weeks. The therapy showed no major side effects except for a transient granulocytopenia. 相似文献
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6.
Yvonne Schaffler Etzel Cardeña Sophie Reijman Daniela Haluza 《Culture, medicine and psychiatry》2016,40(1):74-99
Recent studies in African contexts have revealed a strong association between spirit possession and severe trauma, with inclusion into a possession cult serving at times a therapeutic function. Research on spirit possession in the Dominican Republic has so far not included quantitative studies of trauma and dissociation. This study evaluated demographic variables, somatoform dissociative symptoms, and potentially traumatizing events in the Dominican Republic with a group of Vodou practitioners that either do or do not experience spirit possession. Inter-group comparisons revealed that in contrast to non-possessed participants (n = 38), those experiencing spirit possession (n = 47) reported greater somatoform dissociation, more problems with sleep, and previous exposure to mortal danger such as assaults, accidents, or diseases. The two groups did not differ significantly in other types of trauma. The best predictor variable for group classification was somatoform dissociation, although those items could also reflect the experience of followers during a possession episode. A factor analysis across variables resulted in three factors: having to take responsibility early on in life and taking on a professional spiritual role; traumatic events and pain; and distress/dissociation. In comparison with the non-possessed individuals, the possessed ones did not seem to overall have a remarkably more severe story of trauma and seemed to derive economic gains from possession practice. 相似文献
7.
Up to now, the productivity of mammalian cell culture has been perceived as limiting the productivity of the industrial manufacture of therapeutic monoclonal antibodies. Dramatic improvements in cell culture performance have changed this picture, and the throughput of antibody purification processes is gaining increasing attention. Although chromatographic separations currently are the centerpiece of antibody purification, mostly due to their high resolving power, it becomes more and more apparent that there may be limitations at the very large scale. This review will discuss a number of alternatives to chromatographic antibody purification, with a particular emphasis on the ability to increase throughput and overcome traditional drawbacks of column chromatography. Specifically, precipitation, membrane chromatography, high-resolution ultrafiltration, crystallization, and high-pressure refolding will be evaluated as potential large scale unit operations for industrial antibody production. 相似文献
8.
Mutations at residues 282, 286, and 293 of phage lambda integrase exert pathway-specific effects on synapsis and catalysis in recombination 下载免费PDF全文
Bankhead TM Etzel BJ Wolven F Bordenave S Boldt JL Larsen TA Segall AM 《Journal of bacteriology》2003,185(8):2653-2666
Bacteriophage lambda integrase (Int) catalyzes site-specific recombination between pairs of attachment (att) sites. The att sites contain weak Int-binding sites called core-type sites that are separated by a 7-bp overlap region, where cleavage and strand exchange occur. We have characterized a number of mutant Int proteins with substitutions at positions S282 (S282A, S282F, and S282T), S286 (S286A, S286L, and S286T), and R293 (R293E, R293K, and R293Q). We investigated the core- and arm-binding properties and cooperativity of the mutant proteins, their ability to catalyze cleavage, and their ability to form and resolve Holliday junctions. Our kinetic analyses have identified synapsis as the rate-limiting step in excisive recombination. The IntS282 and IntS286 mutants show defects in synapsis in the bent-L and excisive pathways, respectively, while the IntR293 mutants exhibit synapsis defects in both the excision and bent-L pathways. The results of our study support earlier findings that the catalytic domain also serves a role in binding to core-type sites, that the core contacts made by this domain are important for both synapsis and catalysis, and that Int contacts core-type sites differently among the four recombination pathways. We speculate that these residues are important for the proper positioning of the catalytic residues involved in the recombination reaction and that their positions differ in the distinct nucleoprotein architectures formed during each pathway. Finally, we found that not all catalytic events in excision follow synapsis: the attL site probably undergoes several rounds of cleavage and ligation before it synapses and exchanges DNA with attR. 相似文献
9.
Allison DB Fernandez JR Heo M Zhu S Etzel C Beasley TM Amos CI 《American journal of human genetics》2002,70(3):575-585
An attractive feature of variance-components methods (including the Haseman-Elston tests) for the detection of quantitative-trait loci (QTL) is that these methods provide estimates of the QTL effect. However, estimates that are obtained by commonly used methods can be biased for several reasons. Perhaps the largest source of bias is the selection process. Generally, QTL effects are reported only at locations where statistically significant results are obtained. This conditional reporting can lead to a marked upward bias. In this article, we demonstrate this bias and show that its magnitude can be large. We then present a simple method-of-moments (MOM)-based procedure to obtain more-accurate estimates, and we demonstrate its validity via Monte Carlo simulation. Finally, limitations of the MOM approach are noted, and we discuss some alternative procedures that may also reduce bias. 相似文献
10.
Industrial microbiology of solar salt production 总被引:3,自引:0,他引:3
Javor BJ 《Journal of industrial microbiology & biotechnology》2002,28(1):42-47
Solar salterns can be modeled as giant outdoor chemostats, much like a series of dams on a slow-moving river. Microorganisms
and their products play an essential, but sometimes uncharacterized, role in salt production in these ponds, from seawater
salinity up through NaCl saturation. They may physically affect the evaporation process and their by-products may chemically
modify or bind with dissolved ions. Many solar salt facilities engage microbiologists to establish monitoring programs for
analyses of nutrients, standing crop and associated biological variables in the ponds. Other solar salt companies engage microbiologists
only when there are “crises” in the ponds that interfere with salt production. Journal of Industrial Microbiology & Biotechnology (2002) 28, 42–47 DOI: 10.1038/sj/jim/7000173
Received 20 May 2001/ Accepted in revised form 13 June 2001 相似文献