首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
Summary Reevaluation of the previously proposed structure of helminthosporoside, a host-specific toxin fromHelminthosporium sacchari, reveals a sesquiterpenoid bis-digalactoside. The carbohydrate portion of the toxin was characterized by13C-NMR spectroscopy, methylation analyses, FD and FAB mass spectroscopy. The ring size and anomeric configuration of the galactose moieties were determined by utilizing a13C-NMR structural analysis method. A new partial structure is proposed.Acknowledgment. We extend special thanks to C.E. Costello, Department of Chemistry, M.I.T., Cambridge, MA, for FD mass spectral analyses, and to C.E. Ballou, Department of Biochemistry, University of California, Berkeley, CA, for FAB mass spectral analyses. We submit sincere appreciation to both V.N. Reihold, Harvard Medical School, Boston, MA, and P. Albersheim, Department of Chemistry, University of Colorado, Boulder, CO, for methylation analyses. We thank J.S. Frye at the Colorado State University Regional NMR-Center, funded by National Science Foundation grant No. DHE 78-18581, Department of Chemistry, Colorado State University, Fort Collins, Co, for high resolution CMR and NMR, and we are grateful to P.W. Jennings, Department of Chemistry, Montana State University, Bozeman, Mt, for total carbon analyses. This work was supported in part by a Herman Frasch Foundation grant to G.A. Strobel, by NSF grant PCM-78-22517, and funds from the Montana Agricultural Experiment Station. B.P. Mundy acknowledges the partial support of NSF (ISP-801149).  相似文献   

2.
Y Nagata  R Masui  T Akino 《Experientia》1992,48(10):986-988
Twelve neutral free amino acids, i.e. serine, threonine, glutamine, asparagine, alanine, proline, methionine, tyrosine, valine, leucine, isoleucine and phenylalanine, were surveyed for the presence of D-enantiomers in plasma samples from patients with renal diseases and from normal subjects. D-serine, D-alanine and D-proline were found in the patient's plasma. The highest concentrations (D/L ratio) of D-serine, D-alanine and D-proline were 0.2362, 0.2087 and 0.0986, respectively. The sum of the contents of the three D-amino acid was shown to be present in the plasma proteins.  相似文献   

3.
Summary Daily feeding of the common food color Orange II to mice in doses of up to 3.0 g/kg b.wt for 180 days had deleterious effects on somatic and spermatogonial chromosomes. The chromosomal abnormalities induced were breaks, gaps, constrictions, centric fusion, fragments of unknown origin, translocation, deletion, stickiness, ring chromosomes, pyknosis and other bizarre configurations.Grateful acknowledgment is made to Prof. U.S. Srivastava, Zoology Department for providing necessary laboratory facilities.  相似文献   

4.
Summary Silkgland, fatbody, hemolymph and midgut of eri-silkworm present tissue specific turnover in their biochemical correlates in preparation for spinning of the cocoon which is followed by larval-pupal transformation.Acknowledgment. The authors are thankful to Dr R. N. Singh, Principal, for providing the necessary facilities, to Dr A. B. Das, Zoology Dept. Visvabharti University for valuable suggestions and to Indian Council of Agricultural Research, New Delhi, India, for financial assistance.  相似文献   

5.
Summary In the female Indian frog,Rana tigrina (2n=26; NF=52), the female is heterogametic. The heterochromosomes (ZW) are morphologically indistinguishable, but the W chromosome proves by C-banding analysis to be entierly heterochromatic.Acknowledgment. S.C. is grateful to Prof. G.K. Manna, Zoology Department, Kalyani University, Prof. Archana Sharma, Botany Department, Calcutta University and to Prof. T. Sharma, Zoology Department, Banarus Hindu University for encouragements. He is also thankful to Prof. D.K. Choudhuri, Burdwan University for support.  相似文献   

6.
7.
Skin is an organ that is susceptible to damage by external injury, chronic inflammation, and autoimmunity. Tissue damage causes alterations in both the configuration and type of cells in lesional skin. This phenomenon, called tissue remodeling, is a universal biological response elicited by programmed cell death, inflammation, immune disorders, and tumorigenic, tumor proliferative, and cytoreductive activity. In this process, changes in the components of the extracellular matrix are required to provide an environment that facilitates tissue remodeling. Among these extracellular matrix components, periostin, a glycoprotein that is predominantly secreted from dermal fibroblasts, has attracted attention. Periostin localizes in the papillary dermis of normal skin, and is aberrantly expressed in the dermis of lesional skin in atopic dermatitis, scar, systemic/limited scleroderma, melanoma, cutaneous T cell lymphoma, and skin damage caused by allergic/autoimmune responses. Periostin induces processes that result in the development of dermal fibrosis, and activate or protract the immune response. The aim of this review was to summarize recent knowledge of the role of periostin in the pathogenesis of dermatoses, and to explore whether periostin is a potential therapeutic target for skin diseases.  相似文献   

8.
可再生能源互联网对电子系统提出了五大要求:高效性、安全性、可靠性、便利性、宽泛性.为了实现上述要求,可再生能源互联网需要多学科、多方面、多层次的创新.微电子技术将会渗透到可再生能源互联网的各个层级,是可再生能源互联网的重要支撑性技术之一.文章重点围绕固态变压器、分布式储能技术、信息采集芯片技术、通信芯片技术四个方面,阐述了可再生能源互联网中的微电子技术所面临的特殊要求、技术挑战及未来可能的发展趋势.  相似文献   

9.
Activation of Kupffer cells (KCs) induced that inflammatory cytokine production plays a central role in the pathogenesis of HBV infection. The previous studies from our and other laboratory demonstrated miRNAs can regulate TLR-inducing inflammatory responses to macrophage. However, the involvement of miRNAs in HBV-associated antigen-induced macrophage activation is still not thoroughly understood. Here, we evaluated the effects and mechanisms of miR-155 in HBV-associated antigen-induced macrophage activation. First, co-culture assay of HepG2 or HepG2.2.15 cells and RAW264.7 macrophages showed that HepG2.2.15 cells could significantly promote macrophages to produce inflammatory cytokines. Furthermore, we, respectively, stimulated RAW264.7 macrophages, mouse primary peritoneal macrophages, or healthy human peripheral blood monocytes with HBV-associated antigens, including HBcAg, HBeAg, and HBsAg, and found that only HBeAg could steadily enhance the production of inflammatory cytokines in these cells. Subsequently, miRNAs sequencing presented the up- or down-regulated expression of multiple miRNAs in HBeAg-stimulated RAW264.7 cells. In addition, we verified the expression of miR-155 and its precursors BIC gene with q-PCR in the system of co-culture or HBeAg-stimulated macrophages. Meanwhile, the increased miR-155 expression was positively correlation with serum ALT, AST, and HBeAg levels in AHB patients. Although MAPK, PI3K, and NF-κB signal pathways were all activated during HBeAg treatment, only PI3K and NF-κB pathways were involved in miR-155 expression induced by HBeAg stimulation. Consistently, miR-155 over-expression inhibited production of inflammatory cytokines, which could be reversed by knocking down miR-155. Moreover, we demonstrated that miR-155 regulated HBeAg-induced cytokine production by targeting BCL-6, SHIP-1, and SOCS-1. In conclusion, our data revealed that HBeAg augments the expression of miR-155 in macrophages via PI3K and NF-κB signal pathway and the increased miR-155 promotes HBeAg-induced inflammatory cytokine production by inhibiting the expression of BCL-6, SHIP-1, and SOCS-1.  相似文献   

10.
药用植物羌活现状及其民族植物学调查   总被引:6,自引:0,他引:6  
羌活为重要的传统中药和藏药常用药材,大量的汉藏药方和成药均作为重要的配伍药材加以使用。羌活传统产区主要是藏族、羌族和其它少数民族的聚居的高寒山区,经济较为落后,交通不便。由于难以驯化栽培,药材来源主要依赖野生资源采挖,但由于受到种子发育不完全、后熟期长等本身繁殖特性的限制,羌活繁殖和种群恢复主要是通过无性繁殖实现,野生资源恢复受到严重制约。道地产区的调查发现,羌活野生生境正受到前所未有的破坏,包括生境丧失、破碎化、土壤退化、土地利用模式改变和环境变化等;调查还发现近年来羌活药材价格与采挖量之间的关系,以及当地民族植物学方面的状况。羌活野生资源的破坏受到利益驱使、致使采挖时间和方式等利用模式发生改变,极不利于羌活野生资源的保存和种群恢复,若不规范羌活野生资源的利用和引种驯化,进行人工栽培,羌活野生资源不但难以实现可持续利用,而且还将遭到毁灭性破坏,并有灭绝的危险。本文最后提出了药用羌活属植物的保护性开发和可持续利用可能途径。  相似文献   

11.
Summary Reduction of the ketal II of 7-keto-1,4-dimethoxy-4b-methyl-5, 6, 7, 9, 10-hexahydrophenanthrene with lithium in liquid ammonia furnishes a corresponding dihydro derivative, from which a tricyclic triketone, m.p. 121°, is obtained upon acid hydrolysis. This triketone is identical with the recently described antitrans-4b-methyl-1, 2, 3, 4, 4a, 4b, 5, 6, 7, 9, 10, 10-dodecahydro-phenanthrene-1, 4, 7-trione III and thus conforms to the stereochemistry of the natural steroids.  相似文献   

12.
13.
演化是计算机软件的固有特性.了解演化规律,可以改进软件演化过程,提高软件质量,降低维护成本.本文定义类依赖图,将软件系统描述为软件网络,基于网络度量验证软件演化规律,并讨论软件演化建模的可行性.首先针对Lehman的8项演化定律,设计3个方面的网络度量:网络规模、网络质量、以及结构控制.然后基于四个开源软件系统构建软件网络,统计网络度量;实证研究表明:支持Lehman的4项演化定律,否定另外3项,即复杂度提升、持续增长、以及质量折旧定律.最后分别采用E-R模型和模块依附模型模拟软件系统的演化过程,所生成的随机网络同软件网络的比较结果说明,软件演化存在客观规律,能够通过建模来重现甚至优化.  相似文献   

14.
15.
Summary Incubation of red cells with higher concentrations of prolactin in vitro enhanced the cellular sodium level and produced a significant reduction in erythrocyte membrane adenosine triphosphatase activity. This effect was dose and time-dependent. It is the result of an inhibition of the active sodium pump similar to that produced by ouabain, suggesting altered red cell function and electrolyte balance in hyperprolactinemic states.Acknowledgments. Ovine prolactin was generously supplied by Ferring (Malmö, Sweden) and NPA, NIH (Maryland, USA). Thanks are also due to Prof. S. Dutta, Wayne State University, Detroit, for the gift, of ouabain octahydrate and Dr M. Ramachandran and Prof. S. Ramakrishnan, Department of Biochemistry, JIPMER, Pondicherry, for their encouragement and keen interest in this study.  相似文献   

16.
Summary Experiments were performed to analyse the effect of L-cysteine on barley seeds treated with methyl methanesulfonate (MMS) at a critical stage of the cellular cycle. Contrary to expectation, L-cysteine did not protect the barley seeds against MMS damage except for a slight protection at high doses (0.5, 0.7%).Acknowledgments. The author is thankful to Dr K. Kartha, Prairie Regional Laboratory, National Research Council of Canada, Saskatoon, Canada, and Dr D. Lorence, Washington University, St. Louis, for linguistic revision of the paper.  相似文献   

17.
Summary Glycozoline and girinimbine isomers (IV andVII) were synthesized and their activity against 2 bacterial strains, viz.E. coli andS. aureus, and 2 fungal strains, viz.C. albicans andA. niger were studied. The hydroxy synthons (III) were also tested. The authors are thankful to Dr B.N. Apte, Association of Microbiologists of India, Bombay Unit, for providing some of the organisms, to Prof. A.K. De, Indian Institute of Technology, for financial assistance, to Prof. G. D. Shah, Department of Chemistry, Indian Institute of Technology for guidance, encouragement and helpful discussions.  相似文献   

18.
Summary Initial screening of the 2 recently developed immunosuppressive agents, cyclosporin A and cyclosporin C, in 11 murine transplantable neoplasms revealed significant increase of lifespan with long-term survivors after i.p. injection to the ascites tumors, Taper liver, Sarcoma 180J and Ehrlich.This work was supported in part by grant CA-08748 from the National Cancer Institute, National Institutes of HealthDepartment of Health, Education and Welfare. The authors are indebted to Drs Dorris J. Hutchison, M.N. Teller and H. Stähelin for helpful discussions, and to Dr A. von Wartburg of Sandoz AG, Basel, for the supply of the cyclosporins.  相似文献   

19.
The immunohistochemical distribution of histiocytes containing S-100 protein-like antigen in the skin lesions of cutaneous T-cell lymphoma/leukemia is investigated. Marked hyperplasia of these histiocytes is found in two cases of mycosis fungoides.We thank Prof. Y. Ishida, Gunma University School of Medicine, Dr K. Iwata, Kochi Prefectural Central Hospital, Dr M. Motoi, Okayama University Medical School, Dr H. Enzan, Kochi Medical School, for supplying the material.  相似文献   

20.
Principia (Book 1, Sect. 6), Newton's Lemma 28 on the algebraic nonintegrability of ovals has had an unusually mixed reception. Beginning in 1691 with Jakob Bernoulli (who accepted the lemma) and Huygens and Leibniz (who rejected it and offered counterexamples), Lemma 28 has a history of eliciting seemingly contradictory reactions. In more recent times, D.T. Whiteside in 1974 gave an “unchallengeable counterexample,” while the mathematician V.I. Arnol'd in 1987 sided with Bernoulli and called Newton's argument an “astonishingly modern topological proof.” This disagreement mostly stems, we argue, from Newton's vague statement of the lemma. Indeed, we identify several different interpretations of Lemma 28, any one of which Newton may have been intending to assert, and we then test a number of proposed counterexamples to see which, if any, are true counterexamples to one or more of these versions of the lemma. Following this, we study Newton's argument for the lemma to see whether and where it fails to be convincing. In the end, our study of Newton's Lemma 28 provides an answer to the question, Who is right: Huygens, Leibniz, Whiteside and the others who reject the lemma, or Bernoulli, Arnol'd, and the others who accept it? (Received November 6, 2000)  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号