Two-magnon Raman scattering in cuprate superconductors : Evolution of magnetic fluctuations with doping

Blumberg. G.,Liu, R.,Klein, M.V.,Lee, W.C.,Ginsberg, D.M.,Gu, C.,Veal, B.W.,Dabrowski, B. 숙명여자대학교 자연과학연구소 1994 자연과학논문집 Vol.- No.5

We report observation and resonance Raman studies of spin-pair excitations in YBa₂Cu₃O6+n (0.37<x<0.7) and YBa₂Cu₃O6 superconductors. These excitations at energy ∼3J(2700±150cm-1), similar to two-magnon excitations in insulators, are evidence that antiferromagnetic fluctuations with spatial extent of at least three lattice constants are not overdamped in the underdoped superconductors. With optimal hole doping, where Tc>80 K, the two-magnon peak can no longer be seen above the flat Raman continuum. Photoluminescence and the orgin of the broad-spectrum Raman continuum are also discussed.

Two-magnon Raman scattering in cuprate superconductors : Evolution of magnetic fluctuations with doping

Blumberg. G. Liu, R. Klein, M.V. Lee, W.C. Ginsberg, D.M. Gu, C. Veal, B.W. Dabrowski, B. 숙명여자대학교 자연과학연구소 1994 자연과학논문집 Vol.- No.5

We report observation and resonance Raman studies of spin-pair excitations in YBa₂Cu₃O6+n (0.37<x<0.7) and YBa₂Cu₃O6 superconductors. These excitations at energy ∼3J(2700±150cm-1), similar to two-magnon excitations in insulators, are evidence that antiferromagnetic fluctuations with spatial extent of at least three lattice constants are not overdamped in the underdoped superconductors. With optimal hole doping, where Tc>80 K, the two-magnon peak can no longer be seen above the flat Raman continuum. Photoluminescence and the orgin of the broad-spectrum Raman continuum are also discussed.

Flavonols, Flavones, Flavanones, and Human Health: Epidemiological Evidence

Jeffrey B. Blumberg,Brigitte A.Graf,Paul E.Milbury 한국식품영양과학회 2005 Journal of medicinal food Vol.8 No.3

Polyphenolic flavonoids are among a wide variety of phytochemicals present in the human diet. Basic research,animal model, and human studies suggest flavonoid intake may reduce the risk of several age-related chronic diseases. Thevast number of flavonoids and mixtures of their subclasses, including flavonols, flavones, and flavanones, and the variety ofagricultural practices that affect their concentration in foods have presented a challenge to the development of adequate foodcomposition databases for these compounds. Nonetheless, dietary assessments have been applied to cohort and case-controlepidemiological studies, and several reveal an inverse association with risk of some forms of cancer, cardiovascular disease,and other chronic conditions. Those observational studies that have examined these relationships with regard to flavonols,flavones, and flavanones are reviewed. The requirement for caution in interpreting these studies is discussed with regard tothe limited information available on the bioavailability and biotransformation of these flavonoids. As the totality of the avail-able evidence on these flavonoids suggests a role in the prevention of cancer and cardiovascular disease, further research iswarranted, particularly in controlled clinical trials.

Flavonoids: from Farm to Food to Pharmacokinetics to Function

Jeffrey B. Blumberg 한국식품영양과학회 2015 한국식품영양과학회 학술대회발표집 Vol.2015 No.8

Microplate-Based Oxygen Radical Absorbance Capacity (ORAC) Assay of Hydrophilic and Lipophilic Compartments in Plasma

Kwak Ho Kyung,Blumberg Jeffrey B.,Chen Chung Yen,Milbury Paul E. The Korean Nutrition Society 2006 Nutritional Sciences Vol.9 No.1

Methods have been developed to evaluate the total antioxidant capacity of foods and plasma but limitations are associated with their ability to determine precisely the contribution of lipophilic antioxidants in a lipid milieu as well as interactions among them Thus, we modified the Oxygen Radical Absorbance Capacity (ORAC) assay to determine the peroxyradical scavenging ability of both hydrophilic and lipophilic compartments in plasma The hydrophilic ORAC assay was performed in a phosphate buffer system utilizing 2,2'-azobis (2-amidinopropane) dihydrochloride as a peroxyradical generator and fluorescein as the target The lipophilic ORAC assay was carried out in a dimethylsulfoxide :butyronitrile (DMSO/BN, 9:1 v/v) system using 2,2'-azobis (2,4-dimethyl valeronitrile) as a peroxyradical generator and BODIPY C11 581/591 as the target Analyses were conducted in bovine serum supplemented with water - and lipid - soluble antioxidants and in human plasma. Albumin (0.5$\sim$5 g/dL) and uric acid (0.1$\sim$0.5 $\mu$mol/L) increased hydrophilic ORAC values in a dose-dependent fashion ($R^{2}$=0.97 and 0.98, respectively) but had no impact on lipophilic ORAC values. $\alpha$-Tocopherol (15$\sim$200 $\mu$mol/L) increased lipophilic ORAC values in a dose-dependent fashion ($R^{2}$=0.94); neither $\alpha$-tocopherol nor $\beta$-carotene had an impact on hydrophilic ORAC values. However, addition of $\beta$-carotene at physiological concentration (0.23$\sim$1.86 $\mu$mol/L), either alone or in combination with other carotenoids, had no significant impact on lipophilic ORAC values. Thus, while assays of 'total antioxidant capacity' in biological matrices would be a useful research and clinical tool, existing methods are limited by the lack of complete responsiveness to the full range of dietary antioxidants.

Hyperglycemia and Anthocyanin Inhibit Quercetin Metabolism in HepG2 Cells

Naoto Hashimoto,Jeffrey B. Blumberg,C-Y. Oliver Chen 한국식품영양과학회 2016 Journal of medicinal food Vol.19 No.2

A high glucose (Glu) milieu promotes generation of reactive oxygen species, which may not only cause cellular damage, but also modulate phase II enzymes that are responsible for the metabolism of flavonoids. Thus, we examined the effect of a high Glu milieu on quercetin (Q) metabolism in HepG2 cells. HepG2 cells were grown for 3 days in Glu ranging from 5.5 to 50 mmol/L and/or cyanidin-3-glucoside (C3G) ranging from 0 to 25 μmol/L. Subsequently, the capacity of HepG2 cells to metabolize Q was assessed for up to 16 h. Q metabolites were analyzed by high-performance liquid chromatography. Four major Q metabolites were observed in the culture medium and inside the HepG2 cells. Three of these metabolites appear to be sulfated forms of Q or methylated Q, and one was a methylated Q. These metabolites and Q itself were reduced or tended to be reduced in cells grown in a high Glu compared to a normal Glu medium. Addition of C3G or superoxide dismutase plus catalase did not prevent or enhance reduction of Q metabolites. In vitro, a hyperglycemic milieu decreases the production of the principal Q metabolites in HepG2 cells, mediated through mechanisms independent of oxidative stress.

Electronic Raman scattering in cuprate superconductors and parent insulating phases

Klein, M.V.,Salamon, D.,Blumberg, G.,Cooper, S.L.,Ginsberg, D.M.,Liu, R.,Reznik, D.,Lee, W.C. 숙명여자대학교 자연과학연구소 1994 자연과학논문집 Vol.- No.5

Raman scattering from charge and spin excitations in cuprates is reviewed. The two-magnon resonance Raman profile is used to determine the most probable energy for photon-assisted charge transfer leading to exchange between two spins. The difference between this energy and that for absorption is attributed to spin relaxation (spin polaron) effects. Two-magnon spectra in superconducting cuprates are presented. It is argued that their presence is evidence that the antiferromagnetic correlation length is equal to or greater than three lattice constants. The recently-discovered Raman-active excitons are described and possible assignments of them are discussed. It is pointed out that in highly correlated metals and insulators, the mechanisms for light scattering that are familiar for doped semiconductors or conventional metals are not necessarily the only ones that are operative.

Electronic Raman scattering in cuprate superconductors and parent insulating phases

Klein, M.V.,Salamon, D.,Blumberg, G.,Cooper, S.L.,Ginsberg, D.M.,Liu, R.,Reznik, D.,Lee, W.C. 숙명여자대학교 자연과학연구소 1994 자연과학논문집 Vol.- No.5

Raman scattering from charge and spin excitations in cuprates is reviewed. The two-magnon resonance Raman profile is used to determine the most probable energy for photon-assisted charge transfer leading to exchange between two spins. The difference between this energy and that for absorption is attributed to spin relaxation (spin polaron) effects. Two-magnon spectra in superconducting cuprates are presented. It is argued that their presence is evidence that the antiferromagnetic correlation length is equal to or greater than three lattice constants. The recently-discovered Raman-active excitons are described and possible assignments of them are discussed. It is pointed out that in highly correlated metals and insulators, the mechanisms for light scattering that are familiar for doped semiconductors or conventional metals are not necessarily the only ones that are operative.

Microplate-Based Oxygen Radical Absorbance Capacity(ORAC) Assay of Hydrophilic and Lipophilic Compartments in Plasma

Ho-Kyung Kwak,Jeffrey B. Blumberg,Chung-Yen Chen,Paul E. Milbury 한국영양학회 2006 Nutritional Sciences Vol.9 No.1

Methods have been developed to evaluate the total antioxidant capacity of foods and plasma but limitations are associated with their ability to determine precisely the contribution of lipophilic antioxidants in a lipid milieu as well as interactions among them Thus, we modified the Oxygen Radical Absorbance Capacity (ORAC) assay to determine the peroxyradical scavenging ability of both hydrophilic and lipophilic compartments in plasma. The hydrophilic ORAC assay was performed in a phosphate buffer system utilizing 2,2'-azobis (2-amidinopropane) dihydrochloride as a peroxyradical generator and fluorescein as the target. The lipophilic ORAC assay was carried out in a dimethylsulfoxide: butyronitrile (DMSO/BN, 9:1 v/v) system using2,2'-azobis (2,4-dimethyl valeronitrile) as a peroxyradical generator and BODIPY C11 581/591 as the target. Analyses were conducted in bovine serum supplemented with water-and lipid-soluhle antioxidants and in human plasma. Albumin(0.5~5g/㎗) and uric acid(0.1~0.5 m㏖/ℓ) increased hydrophilic ORAC values in a dose-dependent fashion(R²=0.97 and 0.98, respectively) but had no impact on lipophilic ORAC values. α-Tocopherol (15~200 μ㏖/ℓ) increased lipophilic ORAC values in a dose-dependent fashion (R²=0.94); neither α-tocopherol nor β-carotene had an impact on hydrophilic ORAC values. However, addition of β-carotene at physiological concentrations (0.23~1.86 μ㏖/ℓ), either alone or in combination with other carotenoids, had no significant impact on lipophilic ORAC values. Thus, while assays of "total antioxidant capacity" in biological matrices would be a useful research and clinical tool, existing methods are limited by the lack of complete responsiveness to the full range of dietary antioxidants.

Combination of a Rapidly Penetrating Agonist and a Slowly Penetrating Antagonist Affords Agonist Action of Limited Duration at the Cellular Level

( Larry V. Pearce ),( Jihyae Ann ),( Peter M. Blumberg ),( Jeewoo Lee ) 한국응용약물학회 2019 Biomolecules & Therapeutics(구 응용약물학회지) Vol.27 No.5

The capsaicin receptor TRPV1 (transient receptor potential vanilloid 1) has been an object of intense interest for pharmacological development on account of its critical role in nociception. In the course of structure activity analysis, it has become apparent that TRPV1 ligands may vary dramatically in the rates at which they interact with TRPV1, presumably reflecting differences in their abilities to penetrate into the cell. Using a fast penetrating agonist together with an excess of a slower penetrating antagonist, we find that we can induce an agonist response of limited duration and, moreover, the duration of the agonist response remains largely independent of the absolute dose of agonist, as long as the ratio of antagonist to agonist is held constant. This general approach for limiting agonist duration under conditions in which absolute agonist dose is variable should have more general applicability.