Negative Parity N* Resonances in an Extended GBE

In this paper, we calculate the masses and mixing angles of L=1 negative parity N* resonances in an extended GBE (Goldstone-boson-exchange model) with harmonic-oscillator wave functions. By using those mixing angles, we get their photoproduction amplitudes, and compare them with experimental data and the results of OPE (one-pion-exchange model), OPsE (only pseudoscalar meson exchange model), and OGE (one-gluon-exchange model). We find that the extended GBE gives right internal wave functions. It is essential to extend GBE to include not only pseudoscalar meson exchanges but also vector meson exchanges.Comment: 11 pages, no figure, accepted by Nucl. Phys.

Origins of the baryon spectrum

I begin with a key problem of light and strange baryon spectroscopy which suggests a clue for our understanding of underlying dynamics. Then I discuss spontaneous breaking of chiral symmetry in QCD, which implies that at low momenta there must be quasiparticles - constituent quarks with dynamical mass, which should be coupled to other quasiparticles - Goldstone bosons. Then it is natural to assume that in the low-energy regime the underlying dynamics in baryons is due to Goldstone boson exchange (GBE) between constituent quarks. Using as a prototype of the microscopical quark-gluon degrees of freedom the instanton-induced 't Hooft interaction I show why the GBE is so important. When the 't Hooft interaction is iterated in the qq t-channel it inevitably leads to a pole which corresponds to GBE. This is a typical antiscreening behavior: the interaction is represented by a bare vertex at large momenta, but it blows up at small momenta in the channel with GBE quantum numbers, explaining thus a distinguished role of the latter interaction in the low-energy regime. I show how the explicitly flavour-dependent short-range part of the GBE interaction between quarks, perhaps in combination with the vector-meson exchange interaction, solves a key problem of baryon spectroscopy and present spectra obtained in a simple analytical calculation as well as in exact semirelativistic three-body approach.Comment: Plenary talk given at PANIC 99 (XV Particles and Nuclei International Conference, 10 - 16 June 1999, Uppsala

Multiquark states in a Goldstone boson exchange model

We discuss the stability of multiquark systems containing heavy flavours. We show that the Goldstone boson exchange (GBE) model gives results at variance with the one-gluon-exchange (OGE) model, i.e. when the GBE model stabilizes a system the OGE model destabilizes it and vice-versa.Comment: 7 pages, RevTeX, Talk given at Joint ECT*/TJNAF workshop on N* physics and non-perturbative QCD, May 18-29, 1998, ECT*, Trento, Italy, to be published in Few-Body Systems Supp

Evaluation of prevention of DNA damage and induction of DNA repair in Saccharomyces cerevisiae by Ginkgo biloba leaf extracts

Extracts of Ginkgo biloba leaves (GBE) have been used for centuries in traditional oriental medicine to treat a very wide range of ailments. These extracts contain flavone glycosides, terpene trilactones (ginkgolides and bilobalide), ginkgolic acids, proanthocyanides and other uncharacterized compounds. The flavone glycosides and terpene trilactones fractions are believed to be responsible for the pharmacological properties of GBE, which are very popular, making it as one of the best-selling herbal medications worldwide. In this work we investigated the DNA protective effect of GBE in the model organism Saccharomyces cerevisiae. Typical experiments involved incubation of yeast cells with GBE before and during oxidative shock by hydrogen peroxide. Our results obtained with the comet assay show that DNA damage is significantly decreased upon GBE treatment (before and during H2O2 incubation) in a dose-dependent manner. In addition, DNA repair is significantly improved in cells pre-treated with GBE. As expected, GBE treatment improved survival of yeast cells when challenged with oxidative shock with H2O2. Intracellular oxidation of yeast cells was considerably decreased upon pre-treatment with GBE as revealed by flow cytometry with the redox sensitive probe dichlorofluorescein diacetate. Even in the absence of H2O2, yeast cells showed a decreased intracellular oxidation state, suggesting that GBE can protect cells from endogenous reactive oxygen species

Examining Brain-Cognition Effects of Ginkgo Biloba Extract: Brain Activation in the Left Temporal and Left Prefrontal Cortex in an Object Working Memory Task

Ginkgo Biloba extract (GBE) is increasingly used to alleviate symptoms of age related cognitive impairment, with preclinical evidence pointing to a pro-cholinergic effect. While a number of behavioral studies have reported improvements to working memory (WM) associated with GBE, electrophysiological studies of GBE have typically been limited to recordings during a resting state. The current study investigated the chronic effects of GBE on steady state visually evoked potential (SSVEP) topography in nineteen healthy middle-aged (50-61 year old) male participants whilst completing an object WM task. A randomized double-blind crossover design was employed in which participants were allocated to receive 14 days GBE and 14 days placebo in random order. For both groups, SSVEP was recorded from 64 scalp electrode sites during the completion of an object WM task both pre- and 14 days post-treatment. GBE was found to improve behavioural performance on the WM task. GBE was also found to increase the SSVEP amplitude at occipital and frontal sites and increase SSVEP latency at left temporal and left frontal sites during the hold component of the WM task. These SSVEP changes associated with GBE may represent more efficient processing during WM task completion

Short-Term Effects of Ginkgo biloba Extract on Peripapillary Retinal Blood Flow in Normal Tension Glaucoma

PURPOSE: Based on the vascular theory of glaucoma pathogenesis, we wanted to evaluate the effect of Ginkgo biloba extract (GBE) on peripapillary blood flow in patients with normal tension glaucoma (NTG). METHODS: Thirty patients with NTG were randomly placed in the GBE-treated or control groups. The GBE-treated group received 80 mg GBE orally, twice a day for four weeks, and the control group received a placebo twice a day for four weeks. Complete ocular examinations including visual field, Heidelberg retina flowmeter, and systemic examinations were performed on the first study day and on the day treatment was completed. RESULTS: After GBE treatment, the mean blood flow, volume, and velocity increased at almost all points, and there was a statistically significant increase in blood flow at almost all points, in comparison to the placebo. Blood volume significantly increased only in the superior nasal and superior temporal neuroretinal rim areas. GBE also significantly increased blood velocity in areas of the inferior temporal neuroretinal rim and superior temporal peripapillary area. CONCLUSIONS: GBE administration appears to have desirable effect on ocular blood flow in NTG patients.ope

Ginkgo biloba Extract (GbE) Stimulates the Hypothalamic Serotonergic System and Attenuates Obesity in Ovariectomized Rats

Menopause is associated with increased risk to develop obesity but the mechanisms involved are not fully understood. We have shown that Ginkgo biloba extract (GbE) improved diet-induced obesity. Since GbE might be effective in the treatment of obesity related to menopause, avoiding the side effects of hormone replacement therapy, we investigated the effect of GbE on hypothalamic systems controlling energy homeostasis. Wistar rats were either ovariectomized (OVX) or Sham-operated. After 2 months, either 500 mg.kg(-1) of GbE or vehicle were administered daily by gavage for 14 days. A subset of animals received an intracerebroventricular (i.c.v.) injection of serotonin (300 mu g) or vehicle and food intake was measured after 12 and 24 h. Another subset was submitted to in vivo microdialysis and 5-HT levels of the medial hypothalamus were measured by high performance liquid chromatography, before and up to 2 h after the administration of 500 mg.kg(-1) of GbE. Additional animals were used for quantification of 5-HT1A, 5-HT1B, 5-HT2C, 5-HTT, and pro-opiomelanocortin hypothalamic protein levels by Western blotting. OVX increased food intake and body weight and adiposity while GbE attenuated these alterations. i.c.v. serotonin significantly reduced food intake in Sham, Sham + GbE, and OVX + GbE groups while it failed to do so in the OVX group. In the OVX rats, GbE stimulated 5-HT microdialysate levels while it reduced hypothalamic 5-HTT protein levels. The results indicate that GbE improved the ovariectomy-induced resistance to serotonin hypophagia, at least in part through stimulation of the hypothalamic serotonergic activity. Since body weight gain is one of the most important consequences of menopause, the stimulation of the serotonergic transmission by GbE may represent a potential alternative therapy for menopause-related obesity.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Univ Fed Sao Paulo, Dept Fisiol, Disciplina Fisiol Nutr, Sao Paulo, BrazilUniv Fed Sao Paulo, Dept Ciencias Biol, Setor Morfofisiol & Patol, Diadema, BrazilUniv Fed Sao Paulo, Dept Fisiol, Disciplina Fisiol Nutr, Sao Paulo, BrazilUniv Fed Sao Paulo, Dept Ciencias Biol, Setor Morfofisiol & Patol, Diadema, BrazilCNPq: 453924/2014-0FAPESP: 2012/03172-4FAPESP: 2014/18435-6Web of Scienc

Analysis of DNA damage and repair in saccharomyces cerevisiae using the comet assay in the characterization of antigenotoxicity of plant extracts and phytochemicals

In this work we used the model organism Saccharomyces cerevisiae to characterise the biological activity and the mechanism of action of phytochemicals. One of the goals is to use mutant strains affected in basic mechanisms of oxidative stress response and DNA repair in order to uncover the molecular targets of phytochemicals. We have assessed DNA damage and repair using the comet assay, evaluated as “comet tail length”, which displayed a dose-response relationship with different DNA-damaging agents1. Subsequently, we used this system to assess the antigenotoxic properties of a leaf extract from Ginkgo biloba (GBE). Typical experiments involved incubation of yeast cells, or spheroplasts, with GBE before and during oxidative shock with hydrogen peroxide. Our results obtained with the comet assay show that DNA damage was significantly decreased upon GBE treatment in a dose-dependent manner. In addition, DNA repair kinetics was significantly improved in cells incubated with GBE. However, in the mutant strain affected in CDC9, encoding a DNA ligase involved in the mechanisms of nucleotide excision repair and base excision repair, oxidative DNA damage repair kinetics was unchanged with GBE, suggesting that the activity of this extract involves one of these mechanisms, or both. Hydrogen peroxide-induced cell cycle arrest in G2 was abolished when cells were incubated with GBE after oxidative shock, suggesting that the improved repair kinetics allows progression of the cell cycle and/or GBE can have a direct effect on its regulation. As expected, GBE treatment improved survival of yeast cells when challenged with oxidative shock with H2O2 and intracellular oxidation was considerably decreased upon pre-treatment with GBE as revealed by flow cytometry. Reference(s) 1. Azevedo F., Marques, F., Fokt, H., Oliveira, R. and Johansson, B. (2011) Measuring oxidative DNA damage and DNA repair using the yeast comet assay. Yeast, 28, 55-6