Giuseppe Squadrito | University of Alabama at Birmingham (original) (raw)
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Papers by Giuseppe Squadrito
Proceedings of the National Academy of Sciences, 2007
The consumption of garlic is inversely correlated with the progression of cardiovascular disease,... more The consumption of garlic is inversely correlated with the progression of cardiovascular disease, although the responsible mechanisms remain unclear. Here we show that human RBCs convert garlic-derived organic polysulfides into hydrogen sulfide (H 2 S), an endogenous cardioprotective vascular cell signaling molecule. This H 2 S production, measured in real time by a novel polarographic H 2 S sensor, is supported by glucose-maintained cytosolic glutathione levels and is to a large extent reliant on reduced thiols in or on the RBC membrane. H 2 S production from organic polysulfides is facilitated by allyl substituents and by increasing numbers of tethering sulfur atoms. Allyl-substituted polysulfides undergo nucleophilic substitution at the α carbon of the allyl substituent, thereby forming a hydropolysulfide (RS n H), a key intermediate during the formation of H 2 S. Organic polysulfides (R-S n -R′; n > 2) also undergo nucleophilic substitution at a sulfur atom, yielding RS n H a...
The American journal of physiology, 1995
Nitric oxide and superoxide, which are produced by several cell types, rapidly combine to form pe... more Nitric oxide and superoxide, which are produced by several cell types, rapidly combine to form peroxynitrite. This reaction can result in nitric oxide scavenging, and thus mitigation of the biological effects of superoxide. Also, superoxide can trap and hence modulate the effects of nitric oxide; superoxide dismutase, by controlling superoxide levels, therefore can influence the reaction pathways open to nitric oxide. The production of peroxynitrite, however, causes its own sequelae of events: Although neither .NO nor superoxide is a strong oxidant, peroxynitrite is a potent and versatile oxidant that can attack a wide range of biological targets. The peroxynitrite anion is relatively stable, but its acid, peroxynitrous acid (HOONO), rearranges to form nitrate with a half-life of approximately 1 s at pH 7, 37 degrees C. HOONO exists as a Boltzmann distribution of rotamers; at 5-37 degrees C HOONO has an apparent acidity constant, pKa,app, of 6.8. Oxidation reactions of HOONO can inv...
Revista De Quimica, Apr 20, 2013
Free Radical Biol Med, 1996
Proceedings of the American Thoracic Society, Dec 20, 2012
The Faseb Journal, Apr 1, 2007
Chemico Biological Interactions, May 19, 1995
Archives of Biochemistry and Biophysics, Oct 1, 1995
Revista De Quimica, Mar 13, 2013
Environmental and Molecular Mutagenesis, 1991
Revista De Quimica, Feb 21, 2013
Chemical Research in Toxicology
Methods in Enzymology, 2000
Evolution
Populations of Drosophila melanogaster face significant mortality risks from parasitoid wasps tha... more Populations of Drosophila melanogaster face significant mortality risks from parasitoid wasps that use species‐specific strategies to locate and survive in hosts. We tested the hypothesis that parasitoids with different strategies select for alternative host defense characteristics and in doing so contribute to the maintenance of fitness variation and produce trade‐offs among traits. We characterized defense traits of Drosophila when exposed to parasitoids with different host searching behaviors (Aphaereta sp. and Leptopilina boulardi). We used host larvae with different natural alleles of the gene Dopa decarboxylase (Ddc), a gene controlling the production of dopamine and known to influence the immune response against parasitoids. Previous population genetic analyses indicate that our focal alleles are maintained by balancing selection. Genotypes exhibited a trade‐off between the immune response against Aphaereta sp. and the ability to avoid parasitism by L. boulardi. We also ident...
Proceedings of the National Academy of Sciences, 2007
The consumption of garlic is inversely correlated with the progression of cardiovascular disease,... more The consumption of garlic is inversely correlated with the progression of cardiovascular disease, although the responsible mechanisms remain unclear. Here we show that human RBCs convert garlic-derived organic polysulfides into hydrogen sulfide (H 2 S), an endogenous cardioprotective vascular cell signaling molecule. This H 2 S production, measured in real time by a novel polarographic H 2 S sensor, is supported by glucose-maintained cytosolic glutathione levels and is to a large extent reliant on reduced thiols in or on the RBC membrane. H 2 S production from organic polysulfides is facilitated by allyl substituents and by increasing numbers of tethering sulfur atoms. Allyl-substituted polysulfides undergo nucleophilic substitution at the α carbon of the allyl substituent, thereby forming a hydropolysulfide (RS n H), a key intermediate during the formation of H 2 S. Organic polysulfides (R-S n -R′; n > 2) also undergo nucleophilic substitution at a sulfur atom, yielding RS n H a...
The American journal of physiology, 1995
Nitric oxide and superoxide, which are produced by several cell types, rapidly combine to form pe... more Nitric oxide and superoxide, which are produced by several cell types, rapidly combine to form peroxynitrite. This reaction can result in nitric oxide scavenging, and thus mitigation of the biological effects of superoxide. Also, superoxide can trap and hence modulate the effects of nitric oxide; superoxide dismutase, by controlling superoxide levels, therefore can influence the reaction pathways open to nitric oxide. The production of peroxynitrite, however, causes its own sequelae of events: Although neither .NO nor superoxide is a strong oxidant, peroxynitrite is a potent and versatile oxidant that can attack a wide range of biological targets. The peroxynitrite anion is relatively stable, but its acid, peroxynitrous acid (HOONO), rearranges to form nitrate with a half-life of approximately 1 s at pH 7, 37 degrees C. HOONO exists as a Boltzmann distribution of rotamers; at 5-37 degrees C HOONO has an apparent acidity constant, pKa,app, of 6.8. Oxidation reactions of HOONO can inv...
Revista De Quimica, Apr 20, 2013
Free Radical Biol Med, 1996
Proceedings of the American Thoracic Society, Dec 20, 2012
The Faseb Journal, Apr 1, 2007
Chemico Biological Interactions, May 19, 1995
Archives of Biochemistry and Biophysics, Oct 1, 1995
Revista De Quimica, Mar 13, 2013
Environmental and Molecular Mutagenesis, 1991
Revista De Quimica, Feb 21, 2013
Chemical Research in Toxicology
Methods in Enzymology, 2000
Evolution
Populations of Drosophila melanogaster face significant mortality risks from parasitoid wasps tha... more Populations of Drosophila melanogaster face significant mortality risks from parasitoid wasps that use species‐specific strategies to locate and survive in hosts. We tested the hypothesis that parasitoids with different strategies select for alternative host defense characteristics and in doing so contribute to the maintenance of fitness variation and produce trade‐offs among traits. We characterized defense traits of Drosophila when exposed to parasitoids with different host searching behaviors (Aphaereta sp. and Leptopilina boulardi). We used host larvae with different natural alleles of the gene Dopa decarboxylase (Ddc), a gene controlling the production of dopamine and known to influence the immune response against parasitoids. Previous population genetic analyses indicate that our focal alleles are maintained by balancing selection. Genotypes exhibited a trade‐off between the immune response against Aphaereta sp. and the ability to avoid parasitism by L. boulardi. We also ident...