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  • Vallee, Bert L.  (12)
  • 1995-1999  (12)
  • Linguistics  (12)
  • Natural Sciences  (12)
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  • 1995-1999  (12)
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  • 1
    Online Resource
    Online Resource
    Daidzin and its antidipsotropic analogs inhibit serotonin and dopamine metabolism in isolated mitochondria
    Proceedings of the National Academy of Sciences ; 1998
    In:  Proceedings of the National Academy of Sciences Vol. 95, No. 5 ( 1998-03-03), p. 2198-2203
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 95, No. 5 ( 1998-03-03), p. 2198-2203
    Abstract: Daidzin, a major active principle of an ancient Chinese herbal treatment ( Radix puerariae ) for alcohol abuse, selectively suppresses ethanol intake in all rodent models tested. It also inhibits mitochondrial aldehyde dehydrogenase (ALDH-2). Studies on ethanol intake suppression and ALDH-2 inhibition by structural analogs of daidzin established a link between these two activities and suggested that daidzin may suppress ethanol intake by inhibiting ALDH-2. ALDH-2 is a principal enzyme involved in serotonin (5-HT) and dopamine (DA) metabolism. Thus, daidzin may act by inhibiting 5-HT and DA metabolism. To evaluate this possibility, we have studied the effect of daidzin and its analogs on 5-HT and DA metabolism in isolated hamster and rat liver mitochondria. Daidzin potently inhibits the formation of 5-hydroxyindole-3-acetic acid (5-HIAA) and 3,4-dihydroxyphenylacetic acid (DOPAC) from their respective amines in isolated mitochondria. Inhibition is concentration-dependent and is accompanied by a concomitant accumulation of 5-hydroxyindole-3-acetaldehyde and 3,4-dihydroxyphenylacetaldehyde. Daidzin analogs that suppress hamster ethanol intake also inhibit 5-HIAA and DOPAC formation. Comparing their effects on mitochondria-catalyzed 5-HIAA or DOPAC formation and hamster ethanol intake reveals a positive correlation—the stronger the inhibition on 5-HIAA or DOPAC formation, the greater the ethanol intake suppression. Daidzin and its active analogs, at concentrations that significantly inhibit 5-HIAA formation, have little or no effect on mitochondria-catalyzed 5-HT depletion. It appears that the antidipsotropic action of daidzin is not mediated by 5-HT (or DA) but rather by its reactive intermediates 5-hydroxyindole-3-acetaldehyde and, presumably, 3,4-dihydroxyphenylacetaldehyde as well, which accumulates in the presence of daidzin.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.95.5.2198
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 1998
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
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  • 2
    Online Resource
    Online Resource
    Chimeric anti-angiogenin antibody cAb 26–2F inhibits the formation of human breast cancer xenografts in athymic mice
    Proceedings of the National Academy of Sciences ; 1998
    In:  Proceedings of the National Academy of Sciences Vol. 95, No. 8 ( 1998-04-14), p. 4579-4583
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 95, No. 8 ( 1998-04-14), p. 4579-4583
    Abstract: Angiogenin (Ang), an inducer of neovascularization, is secreted by several types of human tumor cells and appears critical for their growth. The murine anti-Ang monoclonal antibody (mAb) 26–2F neutralizes the activities of Ang and dramatically prevents the establishment and metastatic dissemination of human tumor cell xenografts in athymic mice. However, for use clinically, the well-documented problem of the human anti-globulin antibody response known to occur with murine antibodies requires resolution. As a result, chimeric as well as totally humanized antibodies are currently being evaluated as therapeutic agents for the treatment of several pathological conditions, including malignancy. Therefore, we have constructed a chimeric mouse/human antibody based on the structure of mAb 26–2F. Complementary DNAs from the light and heavy chain variable regions of mAb 26–2F were cloned, sequenced, and genetically engineered by PCR for subcloning into expression vectors that contain human constant region sequences. Transfection of these vectors into nonproducing mouse myeloma cells resulted in the secretion of fully assembled tetrameric molecules. The chimeric antibody (cAb 26–2F) binds to Ang and inhibits its ribonucleolytic and angiogenic activities as potently as mAb 26–2F. Furthermore, the capacities of cAb 26–2F and its murine counterpart to suppress the formation of human breast cancer tumors in athymic mice are indistinguishable. Thus cAb 26–2F, with its retained neutralization capability and likely decreased immunogenicity, may be of use clinically for the treatment of human cancer and related disorders where pathological angiogenesis is a component.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.95.8.4579
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 1998
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
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  • 3
    Online Resource
    Online Resource
    Control of zinc transfer between thionein, metallothionein, and zinc proteins
    Proceedings of the National Academy of Sciences ; 1998
    In:  Proceedings of the National Academy of Sciences Vol. 95, No. 7 ( 1998-03-31), p. 3489-3494
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 95, No. 7 ( 1998-03-31), p. 3489-3494
    Abstract: Metallothionein (MT), despite its high metal binding constant ( K Zn = 3.2 × 10 13 M −1 at pH 7.4), can transfer zinc to the apoforms of zinc enzymes that have inherently lower stability constants. To gain insight into this paradox, we have studied zinc transfer between zinc enzymes and MT. Zinc can be transferred in both directions—i.e., from the enzymes to thionein (the apoform of MT) and from MT to the apoenzymes. Agents that mediate or enhance zinc transfer have been identified that provide kinetic pathways in either direction. MT does not transfer all of its seven zinc atoms to an apoenzyme, but apparently contains at least one that is more prone to transfer than the others. Modification of thiol ligands in MT zinc clusters increases the total number of zinc ions released and, hence, the extent of transfer. Aside from disulfide reagents, we show that selenium compounds are potential cellular enhancers of zinc transfer from MT to apoenzymes. Zinc transfer from zinc enzymes to thionein, on the other hand, is mediated by zinc-chelating agents such as Tris buffer, citrate, or glutathione. Redox agents are asymmetrically involved in both directions of zinc transfer. For example, reduced glutathione mediates zinc transfer from enzymes to thionein, whereas glutathione disulfide oxidizes MT with enhanced release of zinc and transfer of zinc to apoenzymes. Therefore, the cellular redox state as well as the concentration of other biological chelating agents might well determine the direction of zinc transfer and ultimately affect zinc distribution.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.95.7.3489
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 1998
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
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  • 4
    Online Resource
    Online Resource
    The glutathione redox couple modulates zinc transfer from metallothionein to zinc-depleted sorbitol dehydrogenase
    Proceedings of the National Academy of Sciences ; 1998
    In:  Proceedings of the National Academy of Sciences Vol. 95, No. 7 ( 1998-03-31), p. 3483-3488
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 95, No. 7 ( 1998-03-31), p. 3483-3488
    Abstract: The release and transfer of zinc from metallothionein (MT) to zinc-depleted sorbitol dehydrogenase (EC 1.1.1.14 ) in vitro has been used to explore the role of MT in cellular zinc distribution. A 1:1 molar ratio of MT to sorbitol dehydrogenase is required for full reactivation, indicating that only one of the seven zinc atoms of MT is transferred in this process. Reduced glutathione (GSH) and glutathione disulfide (GSSG) are critical modulators of both the rate of zinc transfer and the ultimate number of zinc atoms transferred. GSSG increases the rate of zinc transfer 3-fold, and its concentration is the major determinant for efficient zinc transfer. GSH has a dual function. In the absence of GSSG, it inhibits zinc transfer from MT, indicating that MT is in a latent state under the relatively high cellular concentrations of GSH. In addition, it primes MT for the reaction with GSSG by enhancing the rate of zinc transfer 10-fold and by increasing the number of zinc atoms transferred to four. 65 Zn-labeling experiments confirm the release of one zinc from MT in the absence of glutathione and the more effective release of zinc in the presence of GSH and GSSG. In vivo , MT may keep the cellular concentrations of free zinc very low and, acting as a temporary cellular reservoir, release zinc in a process that is dynamically controlled by its interactions with both GSH and GSSG. These results suggest that a change of the redox state of the cell could serve as a driving force and signal for zinc distribution from MT.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.95.7.3483
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 1998
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
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  • 5
    Online Resource
    Online Resource
    Selenium redox biochemistry of zinc–sulfur coordination sites in proteins and enzymes
    Proceedings of the National Academy of Sciences ; 1999
    In:  Proceedings of the National Academy of Sciences Vol. 96, No. 5 ( 1999-03-02), p. 1910-1914
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 96, No. 5 ( 1999-03-02), p. 1910-1914
    Abstract: Selenium has been increasingly recognized as an essential element in biology and medicine. Its biochemistry resembles that of sulfur, yet differs from it by virtue of both redox potentials and stabilities of its oxidation states. Selenium can substitute for the more ubiquitous sulfur of cysteine and as such plays an important role in more than a dozen selenoproteins. We have chosen to examine zinc–sulfur centers as possible targets of selenium redox biochemistry. Selenium compounds release zinc from zinc/thiolate-coordination environments, thereby affecting the cellular thiol redox state and the distribution of zinc and likely of other metal ions. Aromatic selenium compounds are excellent spectroscopic probes of the otherwise relatively unstable functional selenium groups. Zinc-coordinated thiolates, e.g., metallothionein (MT), and uncoordinated thiolates, e.g., glutathione, react with benzeneseleninic acid (oxidation state +2), benzeneselenenyl chloride (oxidation state 0) and selenocystamine (oxidation state −1). Benzeneseleninic acid and benzeneselenenyl chloride react very rapidly with MT and titrate substoichiometrically and with a 1:1 stoichiometry, respectively. Selenium compounds also catalyze the release of zinc from MT in peroxidation and thiol/disulfide-interchange reactions. The selenoenzyme glutathione peroxidase catalytically oxidizes MT and releases zinc in the presence of t -butyl hydroperoxide, suggesting that this type of redox chemistry may be employed in biology for the control of metal metabolism. Moreover, selenium compounds are likely targets for zinc/thiolate coordination centers in vivo , because the reactions are only partially suppressed by excess glutathione. This specificity and the potential to undergo catalytic reactions at low concentrations suggests that zinc release is a significant aspect of the therapeutic antioxidant actions of selenium compounds in antiinflammatory and anticarcinogenic agents.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.96.5.1910
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 1999
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
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  • 6
    Online Resource
    Online Resource
    Daidzin inhibits mitochondrial aldehyde dehydrogenase and suppresses ethanol intake of Syrian golden hamsters
    Proceedings of the National Academy of Sciences ; 1997
    In:  Proceedings of the National Academy of Sciences Vol. 94, No. 5 ( 1997-03-04), p. 1675-1679
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 94, No. 5 ( 1997-03-04), p. 1675-1679
    Abstract: Daidzin is the major active principle in extracts of radix puerariae , a traditional Chinese medication that suppresses the ethanol intake of Syrian golden hamsters. It is the first isoflavone recognized to have this effect. Daidzin is also a potent and selective inhibitor of human mitochondrial aldehyde dehydrogenase (ALDH-2). To establish a link between these two activities, we have tested a series of synthetic structural analogs of daidzin. The results demonstrate a direct correlation between ALDH-2 inhibition and ethanol intake suppression and raise the possibility that daidzin may, in fact, suppress ethanol intake of golden hamsters by inhibiting ALDH-2. Hamster liver contains not only mitochondrial ALDH-2 but also high concentrations of a cytosolic form, ALDH-1, which is a very efficient catalyst of acetaldehyde oxidation. Further, the cytosolic isozyme is completely resistant to daidzin inhibition. This unusual property of the hamster ALDH-1 isozyme accounts for the fact we previously observed that daidzin can suppress ethanol intake of this species without blocking acetaldehyde metabolism. Thus, the mechanism by which daidzin suppresses ethanol intake in golden hamsters clearly differs from that proposed for the classic ALDH inhibitor disulfiram. We postulate that a physiological pathway catalyzed by ALDH-2, so far undefined, controls ethanol intake of golden hamsters and mediates the antidipsotropic effect of daidzin.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.94.5.1675
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 1997
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
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  • 7
    Online Resource
    Online Resource
    Coordination dynamics of biological zinc “clusters” in metallothioneins and in the DNA-binding domain of the transcription factor Gal4
    Proceedings of the National Academy of Sciences ; 1997
    In:  Proceedings of the National Academy of Sciences Vol. 94, No. 6 ( 1997-03-18), p. 2233-2237
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 94, No. 6 ( 1997-03-18), p. 2233-2237
    Abstract: The almost universal appreciation for the importance of zinc in metabolism has been offset by the considerable uncertainty regarding the proteins that store and distribute cellular zinc. We propose that some zinc proteins with so-called zinc cluster motifs have a central role in zinc distribution, since they exhibit the rather exquisite properties of binding zinc tightly while remaining remarkably reactive as zinc donors. We have used zinc isotope exchange both to probe the coordination dynamics of zinc clusters in metallothionein, the small protein that has the highest known zinc content, and to investigate the potential function of zinc clusters in cellular zinc distribution. When mixed and incubated, metallothionein isoproteins-1 and -2 rapidly exchange zinc, as demonstrated by fast chromatographic separation and radiometric analysis. Exchange kinetics exhibit two distinct phases ( k fast ≃ 5000 min −1 ·M −1 ; k slow ≃ 200 min −1 ·M −1 , pH 8.6, 25°C) that are thought to reflect exchange between the three-zinc clusters and between the four-zinc clusters, respectively. Moreover, we have observed and examined zinc exchange between metallothionein-2 and the Gal4 protein ( k ≃ 800 min −1 ·M −1 , pH 8.0, 25°C), which is a prototype of transcription factors with a two-zinc cluster. This reaction constitutes the first experimental example of intermolecular zinc exchange between heterologous proteins. Such kinetic reactivity distinguishes zinc in biological clusters from zinc in the coordination environment of zinc enzymes, where the metal does not exchange over several days with free zinc in solution. The molecular organization of these clusters allows zinc exchange to proceed through a ligand exchange mechanism, involving molecular contact between the reactants.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.94.6.2233
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 1997
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
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  • 8
    Online Resource
    Online Resource
    A putative angiogenin receptor in angiogenin-responsive human endothelial cells
    Proceedings of the National Academy of Sciences ; 1997
    In:  Proceedings of the National Academy of Sciences Vol. 94, No. 6 ( 1997-03-18), p. 2204-2209
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 94, No. 6 ( 1997-03-18), p. 2204-2209
    Abstract: Angiogenin stimulates both [ 3 H]thymidine incorporation and proliferation of human endothelial cells in sparse cultures. Under these conditions, a 170-kDa cell surface protein can be detected that binds angiogenin specifically. Angiogenin-stimulated cell growth is concentration-dependent and is completely inhibited by an anti-angiogenin monoclonal antibody, but not by a nonimmune control antibody. It is not affected by the nonangiogenic homo log, RNase A, nor by other angiogenic proteins, such as basic fibroblast growth factor and its antibody. Results suggest that under specific conditions, endothelial cells express an angiogenin receptor that may mediate angiogenin-stimulated DNA synthesis and proliferation and play an important role in angiogenin-induced angiogenesis.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.94.6.2204
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 1997
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
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  • 9
    Online Resource
    Online Resource
    Inhibitory sites in enzymes: Zinc removal and reactivation by thionein
    Proceedings of the National Academy of Sciences ; 1999
    In:  Proceedings of the National Academy of Sciences Vol. 96, No. 5 ( 1999-03-02), p. 1936-1940
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 96, No. 5 ( 1999-03-02), p. 1936-1940
    Abstract: Thionein (T) has not been isolated previously from biological material. However, it is generated transiently in situ by removal of zinc from metallothionein under oxidoreductive conditions, particularly in the presence of selenium compounds. T very rapidly activates a group of enzymes in which zinc is bound at an inhibitory site. The reaction is selective, as is apparent from the fact that T does not remove zinc from the catalytic sites of zinc metalloenzymes. T instantaneously reverses the zinc inhibition with a stoichiometry commensurate with its known capacity to bind seven zinc atoms in the form of clusters in metallothionein. The zinc inhibition is much more pronounced than was previously reported, with dissociation constants in the low nanomolar range. Thus, T is an effective, endogenous chelating agent, suggesting the existence of a hitherto unknown and unrecognized biological regulatory system. T removes the metal from an inhibitory zinc-specific enzymatic site with a resultant marked increase of activity. The potential significance of this system is supported by the demonstration of its operations in enzymes involved in glycolysis and signal transduction.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.96.5.1936
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 1999
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
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  • 10
    Online Resource
    Online Resource
    Alcohol in the Western World
    Springer Science and Business Media LLC ; 1998
    In:  Scientific American Vol. 278, No. 6 ( 1998-6), p. 80-85
    Details
    In: Scientific American, Springer Science and Business Media LLC, Vol. 278, No. 6 ( 1998-6), p. 80-85
    Type of Medium: Online Resource
    ISSN: 0036-8733
    URL: Article
    DOI: 10.1038/scientificamerican0698-80
    RVK:
    TA 1000
    RVK:
    WA 15000
    RVK:
    TA 7375
    Language: Unknown
    Publisher: Springer Science and Business Media LLC
    Publication Date: 1998
    detail.hit.zdb_id: 246-X
    detail.hit.zdb_id: 1413371-4
    SSG: 11
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