University of Florence

About: University of Florence is a education organization based out in Florence, Toscana, Italy. It is known for research contribution in the topics: Population & Carbonic anhydrase. The organization has 27292 authors who have published 79599 publications receiving 2341684 citations. The organization is also known as: Università degli studi di Firenze & Universita degli studi di Firenze.

Flavonoids as Antioxidants and Developmental Regulators: Relative Significance in Plants and Humans

Abstract: Phenylpropanoids, particularly flavonoids have been recently suggested as playing primary antioxidant functions in the responses of plants to a wide range of abiotic stresses. Furthermore, flavonoids are effective endogenous regulators of auxin movement, thus behaving as developmental regulators. Flavonoids are capable of controlling the development of individual organs and the whole-plant; and, hence, to contribute to stress-induced morphogenic responses of plants. The significance of flavonoids as scavengers of reactive oxygen species (ROS) in humans has been recently questioned, based on the observation that the flavonoid concentration in plasma and most tissues is too low to effectively reduce ROS. Instead, flavonoids may play key roles as signaling molecules in mammals, through their ability to interact with a wide range of protein kinases, including mitogen-activated protein kinases (MAPK), that supersede key steps of cell growth and differentiation. Here we discuss about the relative significance of flavonoids as reducing agents and signaling molecules in plants and humans. We show that structural features conferring ROS-scavenger ability to flavonoids are also required to effectively control developmental processes in eukaryotic cells.

Hypogonadism as a risk factor for cardiovascular mortality in men: a meta-analytic study

Abstract: Objective: To verify whether hypogonadism represents a risk factor for cardiovascular (CV) morbidity and mortality and to verify whether testosterone replacement therapy (TRT) improves CV parameters in subjects with known CV diseases (CVDs). Design: Meta-analysis. Methods: An extensive Medline search was performed using the following words ‘testosterone, CVD, and males’. The search was restricted to data from January 1, 1969, up to January 1, 2011. Results: Of the 1178 retrieved articles, 70 were included in the study. Among cross-sectional studies, patients with CVD have significantly lower testosterone and higher 17-b estradiol (E2) levels. Conversely, no difference was observed for DHEAS. The association between low testosterone and high E2 levels with CVD was confirmed in a logistic regression model, after adjusting for age and body mass index (hazard ratio (HR)Z0.763 (0.744–0.783) and HRZ1.015 (1.014–1.017), respectively, for each increment of total testosterone and E2 levels; both P!0.0001). Longitudinal studies showed that baseline testosterone level was significantly lower among patients with incident overall- and CV-related mortality, in comparison with controls. Conversely, we did not observe any difference in the baseline testosterone and E2 levels between case and controls for incident CVD. Finally, TRT was positively associated with a significant increase in treadmill test duration and time to 1 mm ST segment depression. Conclusions: Lower testosterone and higher E2 levels correlate with increased risk of CVD and CV mortality. TRT in hypogonadism moderates metabolic components associated with CV risk. Whether low testosterone is just an association with CV risk, or an actual cause–effect relationship, awaits further studies.

Preferential expression of CD30 by human CD4+ T cells producing Th2-type cytokines.

Abstract: A large panel of human CD4+ T helper (Th) cell clones with established Th1, Th2, or Th0 profiles of cytokine secretion were examined for the expression of CD30, a member of the tumor necrosis factor receptor superfamily. Th1 clones expressed poor or no CD30 mRNA, and showed low or undetectable expression of both membrane and soluble CD30 (sCD30) protein, whereas Th2 clones showed both CD30 mRNA and membrane CD30 and released substantial amounts of sCD30. Th0 clones exhibited an intermediate pattern of CD30 expression and release. When T cells from the same donor were stimulated with three different antigens (purified protein derivative, PPD; Toxocara canis excretory/secretory antigen, TES; Lolium perenne group I, Lol p I), production of high concentrations of IFN-gamma, but not expression of CD30 or production of IL-4 and IL-5, were observed at any time after stimulation with PPD. In contrast, both CD30 expression and production of IL-4 and IL-5, but not of IFN-gamma, were concomitantly detectable in TES-...

Faster superoxide dismutase mutants designed by enhancing electrostatic guidance

Abstract: THE enzyme Cu, Zn superoxide dismutase (SOD) protects against oxidative damage by dismuting the superoxide radical O.−2 to molecular oxygen and hydrogen peroxide1–3 at the active-site Cuion4,5 in a reaction that is rate-limited by diffusion3,6 and enhanced by electrostatic guidance7–10. SOD has evolved to be one of the fastest enzymes known ( Vmax ~ 2 x 109 M−1 s−1)6,11. The new crystal structures of human SOD12 show that amino-acid site chains that are implicated in electrostatic guidance8 (Glu 132, Glu 133 and Lys 136) form a hydrogen-bonding network. Here we show that site-specific mutants that increase local positive charge while maintaining this orienting network (Glu→Gin) have faster reaction rates and increased ionic-strength dependence, matching brownian dynamics simulations incorporating electrostatic terms. Increased positive charge alone is insufficient: one charge reversal (Glu→Lys) mutant is slower than the equivalent charge neutralization (Glu→Gin) mutant, showing that the newly introduced positive charge disrupts the orienting network. Thus, electrostatically facilitated diffusion rates can be increased by design, provided the detailed structural integrity of the active-site electrostatic network is maintained.