ISSN:0892-6638    

DOI:10.1096/fasebj.6.9.1612285

出版商:Wiley    

年代:1992

数据来源: WILEY

ISSN:0892-6638    

DOI:10.1096/fasebj.6.9.1612286

出版商:Wiley    

年代:1992

数据来源: WILEY

摘要:

Connective tissues maintain shape against external and internal stress. They are molecular hierarchies in which fundamental building units come together in tiers of increasing complexity and mutual interactions, based on information carried in the precursor molecules secreted by cells. The collagen fibril is the end product of well‐understood self‐aggregation controlled by its amino acid sequences, but the interfibrillar amorphous ground substance has not hitherto been seen as structured by analogous aggregations prescribed by the primary structures of the characteristic glycosaminoglycans dissolved therein. Transmission electron microscopy with morphometry and stereology has demonstrated their existence in tissues. Nuclear magnetic resonance defined their secondary structures, rotary shadowing electron microscopy delineated their aggregates in vitro, and molecular dynamics stimulations showed how the latter can spring from the former. The driving forces to aggregation are hydrophobic and hydrogen bonding, offset by electrostatic repulsion between polyanionic charges. The relative stabilities of the aggregates are determined by this balance, and hence by the position and number of their charges, particularly the sulfate ester groups. Corneal stroma is a system of collagen fibrils, highly ordered to ensure transparency, in which glycosaminoglycan aggregates are suggested to determine the ordered spacing as yardsticks in a way that has parallels in all connective tissues.— Scott, J. E. Supramolecular organization of extracellular matrix glycosaminoglycans, in vitro and in the tissues.FASEB J.6: 2639‐2645; 1992.

ISSN:0892-6638    

DOI:10.1096/fasebj.6.9.1612287

出版商:Wiley    

年代:1992

数据来源: WILEY

摘要:

Bidirectional interactions between the immune and neuroendocrine systems influence specifically physiological activities as diverse as tissue localization of lymphocytes, antibody responses, hypothalamic‐pituitary hormone secretion, and neural signal transmission. Our understanding of intersystem communications has been increased by the delineation of the innervation of immune organs, effects of neuromediators on immune cells, and neuroendocrine responses to individual immune cytokines. Two patterns of responses to neuroimmune mediators have been defined to distinguish between direct alterations in cellular function and the more complex states of differentiation and adaptation that condition the threshold and nature of reactions to subsequent stimuli. Recent identification of the molecular mechanisms of action of neuroimmune mediators is exemplified by elucidation of the requirement for prolactin in T lymphocyte proliferation and of the effects of vasoactive intestinal peptide on B lymphocyte expression of adherence proteins. Further knowledge of the advantages of multisystem integration of functions in host defense may reveal other novel mechanisms of cellular communication and biological adaptation.— Goetzl, E. J.; Sreedharan, S. P. Mediators of communication and adaptation in the neuroendocrine and immune systems.FASEB J.6: 2646‐2652; 1992.

ISSN:0892-6638    

DOI:10.1096/fasebj.6.9.1612288

出版商:Wiley    

年代:1992

数据来源: WILEY

摘要:

The putative endothelin‐converting enzyme (ECE) has been the focus of intense research, both within academia and the pharmaceutical industry. Interest in ECE stems mainly from the hypothesis that development of inhibitors of ECE will provide an effective means of preventing production of endothelin in circumstances where it may play a pathogenic role. Both an aspartic and a metalloprotease have been identified that have characteristics of this putative enzyme. Evidence suggests that the metalloprotease, which is inhibited by phosphoramidon, may be the physiologically relevant converting enzyme. However, it remains to be demonstrated conclusively that any inhibitor of an ECE activity directly alters endogenous endothelin production and/or the pathogenesis of a disease condition in which endothelin is thought to play a primary role.— Opgenorth, T. J.; Wu‐Wong, J. R.; Shiosaki, K. Endothelin‐converting enzymes.FASEB J.6: 2653‐2659; 1992.

ISSN:0892-6638    

DOI:10.1096/fasebj.6.9.1612289

出版商:Wiley    

年代:1992

数据来源: WILEY

摘要:

The traffic ATPases superfamily includes known transporters, both prokaryotic and eukaryotic, including the medically important proteins, P‐glycoprotein, and the cystic fibrosis gene product (CFTR), which is known to be a Cl–channel. The structure and mechanism of action of the best‐studied members of the superfamily, the periplasmic permeases, are described and related to that of CFTR and eukaryotic traffic ATPases in general. The contention is put forward that the distinction between the architecture and mechanisms of action of channels and transporters is blurred.— Ames, G. F.‐L., Lecar, H. ATP‐dependent bacterial transporters and cystric fibrosis: analogy between channels and transporters.FASEB J.6: 2660‐2666; 1992.

ISSN:0892-6638    

DOI:10.1096/fasebj.6.9.1377140

出版商:Wiley    

年代:1992

数据来源: WILEY

摘要:

Human lymphocytes have been used by several researchers to investigate the biological effect of electromagnetic fields (EMF). EMF modulate the response by lymphocytes to lectin stimulation. The size and direction of the effect depends both on the lymphocyte physiology and on the physical parameters characterizing the EMF. Lymphocytes have also been used to investigate the genotoxicity of EMF exposure.— Cadossi, R.; Bersani, F.; Cossarizza, A.; Zucchini, P.; Emilia, G.; Torelli, G.; Franceschi, C. Lymphocytes and low‐frequency electromagnetic fields.FASEB J.6: 2667‐2674; 1992.

ISSN:0892-6638    

DOI:10.1096/fasebj.6.9.1612290

出版商:Wiley    

年代:1992

数据来源: WILEY

摘要:

Free radicals generated by a partial reduction of O2pose a serious hazard to tissues and vital organs, especially membrane lipids, connective tissues, and the nucleic acids of cells. For protection, enzymes have evolved that specifically attack O2–, hydrogen, and organic peroxides, and repair any damage incurred to DNA. With few exceptions, antioxidant enzymes are found in all aerobic and aerotolerant anaerobic organisms. Logic assumes that a basal level of antioxidant enzyme activity is maintained at all times. This may be true. Yet cells must have ways to amplify antioxidant enzyme activity to counter sudden increases in oxygen metabolites. The full details of that regulation arc slowly coming to light. Bacteria possess a series of elaborate and interacting genes that can sense specific increases in intracellular H2O2and O2–. In higher organisms, hormones and metal ion cofactors impose pre‐ and posttranslational control over the genetic expression of antioxidant enzymes. Furthermore, aging, cellular differentiation, and organ specificity must also be factored into the final equation in higher organisms. This review will discuss some of the more recent findings relevant to antioxidant enzyme regulation in bacteria and higher organisms.— Harris, E. D. Regulation of antioxidant enzymes.FASEB J. 6: 2675‐2683; 1992.

ISSN:0892-6638    

DOI:10.1096/fasebj.6.9.1612291

出版商:Wiley    

年代:1992

数据来源: WILEY

摘要:

Pertussis toxin, a protein virulence factor produced byBordetella pertussis, is composed of an A protomer and a B oligomer. The A protomer consists of a single polypeptide, termed the S1 subunit, which disrupts transmembrane signaling by ADP‐ribosylating eukaryotic G‐proteins. The B oligomer, containing five polypeptides, binds to cell receptors (most likely containing carbohydrate) and delivers the S1 subunit. Current knowledge suggests that expression of ADP‐ribosyltransferase activity in target eukaryotic cells arises after1) nucleotides and membrane lipids allosterically promote the release of the S1 subunit; and2) the single disulfide bond in the S1 subunit is reduced by reductants such as glutathione. This model suggests conditions for the proper use of the toxin as an experimental reagent.— Kaslow, H. R.; Burns, D. L. Pertussis toxin and target eukaryotic cells: binding, entry and activation.FASEB J.6: 2684‐2690; 1992.

ISSN:0892-6638    

DOI:10.1096/fasebj.6.9.1612292

出版商:Wiley    

年代:1992

数据来源: WILEY

摘要:

Blood‐forming tissues are organized in well‐defined microenvironments composed of hemopoietic cells and a supportive stroma of connective tissue and endothelium. Hemopoietic cells segregate to various lineages, all derived from a small population of pluripotent stem cells residing in the bone marrow. Regulation of growth and differentiation, particularly under conditions of perturbations, damage, and disease, is mediated by inducer colony‐stimulating factors and interleukins counteracted by inhibitory cytokines. Whereas much is known about the mode of induction of differentiation, insufficient information is available to explain the process of stem cell renewal that is crucial for the longevity of the hemopoietic system. It is also only partially known how inhibition of hemopoietic processes occurs, and what molecules in blood‐forming tissues signal organization into discrete patterns. This paper reviews recent progress that has opened new avenues to a better understanding of this highly complex issue.— Zipori, D. Renewal and differentiation of hemopoietic stem cells.FASEB J.6: 2691‐2697; 1992.

ISSN:0892-6638    

DOI:10.1096/fasebj.6.9.1612293

出版商:Wiley    

年代:1992

数据来源: WILEY