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A Bonfigli

Publications and source records attributed to A Bonfigli.

At least 19 recordsLinked to original sources
PubMed2006

High levels of antioxidant enzymatic defence assure good protection against hypoxic stress in spontaneously diabetic rats.

Recent data from literature report that reactive oxygen species (ROS) seem to play a crucial role in the etiology of both types I and II diabetes. This may render diabetic individuals more prone to oxidative injury when challenged with hypoxic stress. It is in fact well known that many diabetic complications cause ischaemic episodes, with a consequent reduction in oxygen supply to various tissues and organs. To check this hypothesis, in this work we tested type I diabetic individuals' antioxidant capability towards a hypoxic-mediated oxidative challenge. In particular, spontaneously diabetic and age-matched non-diabetic biobreeding (BB) Wistar rats were submitted to chronic normobaric hypoxia, and the response of antioxidant enzymes, as well as redox-sensitive transcription factor NF-kappaB and p53, were monitored. Results show that diabetic subjects present a dramatic enhancement in the major antioxidant enzymes activities, thus supporting the notion of diabetes-related changes in cellular redox status. This allows diabetic individuals to counteract hypoxia-mediated oxidative challenge better than the non-diabetic counterpart. Also the behaviour of both the redox-sensitive nuclear transcription factor NF-kappaB and p53 protein in response to hypoxic stimulation seems to support the hypothesis of a better ROS scavenging efficiency in diabetics under hypoxic conditions. In conclusion, high levels of antioxidant enzymatic defences in diabetic BB rats reflect a positive adaptive response able to assure an efficient protection not only against chronic, diabetes-mediated reactive oxygen species (ROS) overproduction, but also versus further oxidative damage.

Animals↗
PubMed2001

Developmental expression and distribution of amphibian glutathione transferases.

This work is aimed at detecting the expression and location of embryonic Bufo bufo GST (bbGSTP1-1) and adult B. bufo GST (bbGSTP2-2) during toad development, in order to assign a putative role to these enzymes also on the basis of their compartmentalization and to verify whether during the premetamorphic liver ontogeny the bbGSTP2-2 form appears. This study was also performed in the adult liver (the primary site of Pi class GST expression) and in the mature ovary, to discern if the embryonic form derives from maternal form. The results show that the embryos and the ovary express only bbGSTP1-1. Moreover, bbGSTP1-1 distribution is the same both in the early embryos and in the ovary: this strongly suggests that bbGSTP1-1 is of maternal origin. As development goes on, a wide distribution of bbGSTP1-1 all over the differentiating organs is observed. The embryonic liver expresses exclusively the bbGSTP1-1 form, while the adult liver is highly positive only towards the bbGSTP2-2 form. This implies that the switch towards the adult bbGSTP2-2 form occurs in metamorphic or postmetamorphic phases and that the detoxication metabolic requirements of the embryo may be completely fulfilled by the bbGSTP1-1 isoenzyme.

Animals↗
PubMed2000

Biochemical, electrophoretic and immunohistochemical aspects of malate dehydrogenase in truffles (Ascomycotina).

The malate dehydrogenase (MDH; EC 1.1.1.37; L-malate-NAD(+)-oxidoreductase) activities of truffles of the genus Tuber (Tuber melanosporum Vittad., Tuber brumale Vittad., Tuber aestivum Vittad., Tuber magnatum Pico, Tuber rufum Pico) have been characterized with regard to the K(m) and V(max) values in the direct and reverse reactions. The isoelectrofocusing has revealed bands showing pI values ranging from pH 5.85 to 7.8. The MDH of T. melanosporum has been partially purified by hydroxyapatite treatment, DEAE-cellulose and Sephadex G-75 columns. With the partially purified T. melanosporum MDH activity polyclonal anti-T. melanosporum MDH antibodies have been prepared and used to localize MDH in the mycorrhizae and ascocarps of T. melanosporum. These antibodies inhibit T. melanosporum MDH activity as well as that of T. magnatum but not that of rabbit liver; this supports the specificity of the MDH antibodies used to localize MDH in truffle tissues.

Animals↗
PubMed2000

Antioxidant and GSH-related enzyme response to a single teratogenic exposure to the anticonvulsant phenytoin: temporospatial evaluation.

BACKGROUND: It has been proposed that the anticonvulsant drug phenytoin (PHT) requires bioactivation to reactive intermediate(s) to achieve its recognized teratogenic potential and that embryonal detoxification power may play a fundamental role in the teratogenic response. On this basis, we sought to investigate the potential effects of a teratogenic exposure to PHT on the activities of antioxidant and GSH-related detoxifying enzymes in gestational murine tissues. METHODS: Pregnant Swiss mice were injected intraperitoneally with 0 (vehicle) or 65 mg/kg of PHT on gestation day (GD) 12 (plug day = GD 1). Biochemical determinations, including activities of glutathione transferase, glutathione peroxidase, glutathione reductase, glyoxalase I, glyoxalase II, catalase, and superoxide dismutase, were carried out on maternal and embryonic/fetal livers and in placentas on GD 14 and 19. RESULTS: The major findings of this study show that (1) organogenesis-stage conceptal tissues have detectable levels of all the tested enzymes; (2) most of the embryonic liver and placental enzymes investigated undergo a significant induction within 48 hr (GD 14) after PHT administration; and (3) in the same tissues a down-regulation of enzyme activities is noted near term (GD 19). CONCLUSIONS: Overall, these findings show that teratogenic exposure to PHT is associated with a modulation of reactive-intermediates-scavenging enzyme activities, and provide further support for role of generation of reactive intermediates in PHT-induced teratogenesis.

Abortion, Veterinary↗
PubMed1999

Age-dependent ultrastructural alterations and biochemical response of rat skeletal muscle after hypoxic or hyperoxic treatments.

This work deals with the antioxidant enzymatic response and the ultrastructural aspects of the skeletal muscle of young and aged rats kept under hypoxic or hyperoxic normobaric conditions. It is in fact well known that the supply of oxygen at concentrations higher or lower than those occurring under normal conditions can promote oxidative processes that can cause tissue damage. The enzymes investigated were both those directly involved in reactive oxygen species (ROS) scavenging (superoxide dismutase, catalase and selenium-dependent glutathione peroxidase), and those challenged with the detoxication of cytotoxic compounds produced by the action of ROS on biological molecules (glutathione transferase, glyoxalase I, glutathione reductase), in order to obtain a comparative view of the defence strategies used with respect to aging. Our results support the hypothesis that one of the major contributors to the aging process is the oxidative damage produced at least in part by an impairment of the antioxidant enzymatic system. This makes the aged organism particularly susceptible to oxidative stress injury and to the related degenerative diseases, especially in those tissues with high demand for oxidative metabolism.

Aging↗
PubMed1998

Effect of methylglyoxal on Bufo bufo embryo development: morphological and biochemical aspects.

Methylglyoxal (2-oxopropanal) is a cytotoxic compound that can be formed endogenously as a by-product of glycolytic pathway; so its concentration is expected to increase when glycolysis activity increases such as during embryo development. In this work we study the effect of exogenous methylglyoxal on development and embryo viability during Bufo Bufo development and on the enzymes and cofactors involved in its detoxication process (glyoxalase I and II, reduced glutathione and glyceraldehyde 3-phosphate dehydrogenase). The results show that exogenous methylglyoxal does not affect the enzymatic pattern until stage 20, while it induces a significant activity decrease of the tested enzymes at stage 25. On the contrary methylglyoxal positively influences the reduced glutathione concentration at all the considered stages. At morphological and histological levels methylglyoxal causes a strong retardation of cell division in the early stages, that results in various abnormalities in the late development. In conclusion, methylglyoxal enters the embryo and is antiproliferative and teratogenic: the data further supports the hypothesis of the importance of the glyoxalase system in the process of cell growth and division.

Animals↗
PubMed1998

[Notes on the sources for the study of malariatherapy in Italy].

The article presents the results of a critical evaluation of the clinical histories of 1240 cases of progressive paresis recorded in the S. Maria della Pieta (1911-1950) and reconstructs the scientific discussion about the results of malariatherapy and its action mechanism. The bibliographical study led to a regional characterization of the therapy in the scientific orientation and techniques. The authors are now working out the data, hoping for a future debate on the topic.

Clinical Medicine↗
PubMed1997

Aging and detoxifying enzymes responses to hypoxic or hyperoxic treatment.

We studied the levels of antioxidant and detoxifying enzymes in the livers and lungs of young and old rats kept under hypoxic or hyperoxic conditions as models of oxidative stress. In particular, we investigated the levels of enzymes directly involved in active oxygen species scavenging (superoxide dismutase, catalase and glutathione peroxidase-selenium dependent) and enzymes challenged with detoxification processes (glutathione transferase, glyoxalase I and glutathione reductase) in order to obtain a wide comparative view of the defence strategies used with respect to the age of the animals. The results show that the responses of some protective enzymes in young rats are opposite to those of old ones. Some of the changes found appear mainly due to age, while others appear to be due only to the oxygen tensions and are independent of the aging process. The glutathione contents of the liver and lung from young and old rats under hypoxic and hyperoxic conditions were measured.

Aging↗
PubMed1997

Molecular approach to the nucleo-melanosomal interaction in human melanoma cells.

This paper presents evidence that L-tyrosine oxidation products and 5,6-dihydroxyindole, an intermediate of melanin synthesis bind to and modify DNA structure, as tested by extracting cell DNA, using topoisomerase I and denaturation assays. When supercoiled plasmid pCU18 or pBR322 DNAs are treated with 5,6-dihydroxyindole the supercoiled species disappear and are converted to species less mobile in a gel retardation test with respect to relaxed DNA, 5,6-Dihydroxyindole causes an easier acid denaturation of the double helix. The results, that are dose dependent, would point to both intercalation and cross-linking of DNA by 5,6-dihydroxyindole and its oxidation product(s). 3H-L-tyrosine deriving radioactivity, bound to nuclear DNA, is higher at low pH, (5.6) if compared to pH 6.8. The highest radioactivity bound to cell DNA is found during the transition from the amelanotic to the melanotic phenotype in human melanoma cell lines. As a control, the binding of 3H-L-tyrosine radioactivity to human prostate fibroblast DNA was investigated.

Animals↗
PubMed1996

The dinuclear copper site structure of Agaricus bisporus tyrosinase in solution probed by X-ray absorption spectroscopy.

We have measured the x-ray absorption near edge structure (XANES) spectra of the enzyme tyrosinase from the mushroom Agaricus bisporus in solution in the oxy and deoxy forms. The spectra, obtained under the same conditions as the analogous forms of mollusc hemocyanin (Hc), show that the oxidation state of copper changes from Cu(II) (oxy form) to Cu(I) (deoxy form), and the copper active site(s) of A. bisporus tyrosinase in solution undergoes the same main conformational changes as Hc. We have applied the multiple scattering theory to simulate the XANES spectra of various alternative geometries of the copper site, accounting for the residual differences between Hc and tyrosinase. While oxy-Hc is reasonably fitted only by the pseudo-square-pyramidal geometry reported by its crystallographic data, oxytyrosinase can be fitted, starting from the Hc coordinates, either by distortions toward a pseudo-tetrahedral geometry, with inequivalent copper sites, or by an apically distorted square-pyramidal geometry (with an elongation of the apical distance of no more than 0.2 A).

Agaricus↗
PubMed1994

Cyto-genotoxic species leakage within human melanoma melanosomes. Molecular-morphological correlations.

This work studies the phenotype changes, relating to pigment expression, of a human melanoma cell line. The phenotypic instabilities and proliferation rates are correlated with the production and release in the cell culture medium of active oxygen species and melanin synthesis intermediates. The proliferation rates versus L-tyrosine concentration in the culture media are investigated: a decrease is found when high L-tyrosine is added to the medium. This would be consistent with the release of cytotoxic and/or genotoxic species by melanoma cells. The morphology of melanoma melanosomes is coherent with the leakage of cytotoxic and genotoxic species produced during melanin synthesis.

Cell Division↗
PubMed1992

Copper deficiency and pigmentation in the rat: morphofunctional aspects.

The effects of a low copper diet on pigmentation, pigment cell and melanosome morphology have been investigated in ACI/T male rats. After a three months treatment the fur and skin pigmentation is reduced as compared to the controls. The melanocytes of the treated rats show the phenotype of active pigment cells while some melanosomes are abnormally differentiated: both lamellar and granular organelles are present in the same pigment cell and mosaic age melanosomes appear. The abnormal melanosome structure expressed by the treated-rat melanocytes is also evident in vitro. After incubation with deoxycholate the melanosomes from the low-copper diet treated rats are much more altered than those from the control rats. The phenotype of the rats starved for copper seems to mimic as regards pigmentation the phenotype of the mouse Mo (mottled) mutation that is an experimental model of the Menkes' kinky hair syndrome. In conclusion copper deficiency seems to affect both the morphology and function of the pigment cells.

Animals↗
PubMed1990

Changes of a high molecular mass proteinase activity during Bufo bufo development.

1. A chymotrypsin-like proteolytic activity was found both in unfertilized eggs and in embryos of Bufo bufo. 2. A dramatical change of activity can be observed in the course of embryonic development. The activity rapidly increases after fertilization up to the stage 9 followed by a fall to a level close to unfertilized eggs. 3. Gel chromatography analysis reveals, in all stages of development, the presence of a single peak of proteinase activity characterized by a very high molecular mass. 4. Proteinase activity, found change during the development of Bufo bufo, was characterized by substrate specificity, protease inhibitor and pH effect. All results obtained suggest that the chymotrypsin-like activity can be assigned to the multicatalytic proteinase.

Amino Acid Sequence↗
PubMed1990

Mutagenicity test for unstable compounds, such as 5,6-dihydroxyindole, using an Escherichia coli HB101/pBR322 transfection system.

A mutagenicity test for unstable chemical compounds has been devised. The test makes use of (i) in vitro treatment of plasmid pBR322 with the putative mutagen (ii) subsequent transfection of Escherichia coli HB101; (iii) selection either on tetracycline- or ampicillin-containing Eugon agar (iv) cross-antibiotic replica plating and recovery of single antibiotic resistant colonies (v) restriction analysis of pBR322 isolated from single antibiotic resistant colonies. In this work the test has been used to assess the mutagenicity of 5,6-dihydroxyindole, a cytotoxic intermediate of melanin biosynthesis.

Ampicillin Resistance↗
PubMed1987

A study on the in vitro interaction between tyrosinase and glutathione S-transferase.

The actions of glutathione S-transferase and tyrosinase on the in vitro production of glutathionyl-3,4-dihydroxyphenylalanine and the dopachrome level in the presence of GSH and L-3,4-dihydroxyphenylalanine were studied. No clear evidence of complementarity between tyrosinase and glutathione S-transferase was observed; on the contrary, in the presence of glutathione S-transferase the glutathionyl-3,4-dihydroxyphenylalanine yield was lower than with tyrosinase only, as measured by HPLC. It is concluded that the spontaneous conjugation of GSH with dopaquinone should probably be high enough to scavenge the toxic quinone and to produce precursors for phaeomelanogenesis.

Animals↗
PubMed1987

Glutathione transferase activity during Bufo bufo development.

High levels of glutathione transferase activity were measured during the development of the embryos of Bufo bufo including unfertilized eggs. After stage 4 glutathione transferase activity gradually decreased until stage 25 when the minimum was reached. No change in the number of isozymes was noted during development according to isoelectric focusing analysis performed on the cytosolic fractions of selected stages.

Animals↗