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R De Sanctis

Publications and source records attributed to R De Sanctis.

15 recordsLinked to original sources
PubMed2001

Intracellular ascorbic acid enhances the DNA single-strand breakage and toxicity induced by peroxynitrite in U937 cells.

A well-established protocol to increase the intracellular content of ascorbic acid was used to investigate the effects of the vitamin on DNA single-strand breakage and toxicity mediated by authentic peroxynitrite (ONOO(-)) in U937 cells. This protocol involved exposure for 60 min to 100 microM dehydroascorbic acid, which was taken up by the cells and converted into ascorbic acid via a GSH-independent mechanism. At the time of exposure to ONOO(-), which was performed in fresh saline immediately after loading with dehydroascorbic acid, the vitamin present in the cells was all in its reduced form. It was found that, in cells that are otherwise ascorbate-deficient, an increase in their ascorbic acid content does not prevent, but rather enhances, the DNA-damaging and lethal responses mediated by exogenous ONOO(-). These results therefore suggest that acute supplementation of ascorbic acid can be detrimental for individuals with pathologies associated with a decrease in ascorbic acid and in which ONOO(-) is known to promote deleterious effects.

Ascorbic Acid↗
PubMed2001

Quercetin prevents glutathione depletion induced by dehydroascorbic acid in rabbit red blood cells.

Exposure of rabbit red blood cells to dehydroascorbic acid (DHA) caused a significant decline in glutathione content which was largely prevented by quercetin, whereas it was insensitive to various antioxidants, iron chelators or scavengers of reactive oxygen species. This response was not mediated by chemical reduction of either extracellular DHA or intracellular glutathione disulfide. In addition, the flavonoid did not affect the uptake of DHA or its reduction to ascorbic acid. Rather, quercetin appeared to specifically stimulate downstream events promoting GSH formation.

Animals↗
PubMed2000

Dehydroascorbic acid irreversibly inhibits hexokinase activity.

The oxidized form of vitamin C (dehydroascorbic acid, DHA) completely and irreversibly inactivates recombinant human hexokinase type I, in a pseudo-first order fashion. The inactivation reaction occurs without saturation, indicating that DHA does not form a reversible complex with hexokinase. Further characterization of this response revealed that the inactivation does not require oxygen and that dithiothreitol, while able to prevent the DHA-mediated loss of enzyme activity, failed to restore the activity of the DHA-inhibited enzyme. Inactivation was not associated with cleavage of the peptide chain or cross-linking. The decay in enzymatic activity was however both dependent on deprotonation of a residue with an alkaline pKa and associated with covalent binding of DHA to the protein. In addition, inactivation of hexokinase decreased or increased, respectively, in the presence of the substrates glucose or MgATP. Finally, amino acid analysis of the DHA-modified hexokinase revealed a decrease of cysteine residues. Taken together, the above results are consistent with the possibility that covalent binding of the reagent with a thiol group of cysteine is a critical event for the DHA-mediated loss of hexokinase activity.

Amino Acids↗
PubMed1998

Substrates of hexokinase, glucose-6-phosphate dehydrogenase, and glyceraldehyde-3-phosphate dehydrogenase prevent the inhibitory response induced by ascorbic acid/iron and dehydroascorbic acid in rabbit erythrocytes.

Exposure of intact rabbit erythrocytes or erythrocyte lysates to ascorbic acid/FeCl3 in a glucose-free saline promoted a rapid decline in reduced glutathione and this response was paralleled by inactivation of hexokinase. Under the same conditions, the activity of the enzymes glyceraldehyde-3-phosphate dehydrogenase and glucose-6-phosphate dehydrogenase did not show appreciablevariations in intact cells, but was severely inhibited in the cell-free system. Similar results were obtained by replacing ascorbic acid/FeCl3 with dehydroascorbic acid. In addition, both treatments effectively inhibited the activity of purified hexokinase as well as those of glucose-6-phosphate dehydrogenase and glyceraldehyde-3-phosphate dehydrogenase. Further studies using the cell-free system indicated that the inhibition of enzyme activities elicited by either of the two treatments was effectively counteracted by the specific substrates of these enzymes. The fact that the hexokinase substrate glucose freely permeates the plasma membrane, unlike the substrates of glucose-6-phosphate dehydrogenase and glyceraldehyde-3-phosphatedehydrogenase, explains the selective inhibition of hexokinase observed in intact cells. The above results also indicate that dehydroascorbic acid is an inhibitor of these enzymes and strongly suggest that it is at least in part responsible for the effects mediated by the cocktail ascorbic acid/FeCl3.

Animals↗
PubMed1998

Performance of the preliminary definition of improvement in juvenile chronic arthritis patients treated with methotrexate. Italian Pediatric Rheumatology Study Group.

OBJECTIVE: To investigate the performance of the core set of outcome measures and the preliminary definition of improvement (PDI) in the assessment of response to methotrexate (MTX) treatment in children with juvenile chronic arthritis (JCA). METHODS: Data were obtained from an open label, non-controlled trial designed to investigate the efficacy of MTX in children with JCA. All patients had the core set of variables assessed at baseline and after six months of treatment. Variables in the core set are: (1) physician global assessment of disease activity; (2) parent or patient (if appropriate in age) global assessment of overall well being; (3) functional ability; (4) number of joints with active arthritis; (5) number of joints with limited range of motion; (6) erythrocyte sedimentation rate. The PDI specifies that to be classified as improved, a patient must show at least 30% improvement from baseline in three of any six variables in the core set, with no more than one of the remaining variables worsening by more than 30%. RESULTS: A total of 111 JCA patients were included in the study. According to the PDI, after six months of MTX treatment 73 patients (66%) were classified as improved and 38 (34%) as not improved. Among the core set variables, parent assessment detected the highest percentage of patients improved (72%) and functional assessment the lowest (37%). CONCLUSION: The PDI identifies about two thirds of patients with JCA treated with low dose MTX as improved. This proportion is similar to that expected to improve based upon a previous controlled study of low dose, oral MTX and provides preliminary evidence of the definition's validity.

Adolescent↗
PubMed1997

Hexokinase inactivation induced by ascorbic acid/Fe(II) in rabbit erythrocytes is independent of glutathione-reductive processes and appears to be mediated by dehydroascorbic acid.

Recent studies performed in our laboratory demonstrated that rabbit red blood cell hexokinase was remarkably inhibited by the cocktail ascorbic acid/Fe(II) (Stocchi et al., 1994, Arch. Biochem. Biophys. 311, 160-167) and that the formation of dehydroascorbic acid was a key event in this process (Fiorani et al., 1996, Arch. Biochem. Biophys, 334, 357-361). The present study was undertaken to determine the final hexokinase-inactivating species using cell-free extract as a model. Our results demonstrate superimposable kinetics of hexokinase decay promoted by either ascorbic acid/Fe(II) or dehydroascorbic acid in erythrocyte lysates in which the reduced glutathione (GSH) levels were variously manipulated. In particular, neither removal nor addition of this tripeptide was able to significantly alter the rate or extent of hexokinase inhibition. Thus, GSH-reductive processes are dispensable events in the process of hexokinase inhibition promoted by ascorbic acid/Fe(II) in red blood cells. As a consequence, dehydroascorbic acid appears to be the species which directly inhibits hexokinase. This inference is further supported by the observation that addition of dehydroascorbic acid to the purified enzyme leads to a remarkable inhibition in its activity.

Animals↗
PubMed1996

Role of dehydroascorbate in rabbit erythrocyte hexokinase inactivation induced by ascorbic acid/Fe(II).

In this study we investigated the species involved in the process of hexokinase inactivation induced by ascorbic acid/Fe(II) in rabbit erythrocytes. Our results suggest a model in which divalent iron is first oxidized to the trivalent state and then triggers the oxidation of ascorbic acid. The H202 formed during this process accelerates the formation of dehydroascorbic acid, which appears to be necessary and sufficient to induce hexokinase inactivation. This model was validated by showing that: (a) H202-decomposing enzymes, unlike scavengers of the hydroxyl radicals, reduced the extent of hexokinase inactivation; (b) when H202 was used instead of ascorbate/Fe(II), it was unable, even at very high concentrations, to inhibit hexokinase activity; (c) replacing Fe(II) with either Fe(III) or H202 resulted in comparable levels of ascorbic acid-induced hexokinase inactivation; (d) expression of maximal hexokinase inhibiting activity was also triggered via enzyme-catalyzed oxidation of ascorbic acid or direct addition of dehydroascorbic acid; (e) the level of dehydroascorbic acid, which was actively generated in the external medium upon addition of ascorbic acid/Fe(II), increased as a function of time. Taken together, these results demonstrate that the process of hexokinase inactivation induced by ascorbic acid/Fe(II) is mediated by dehydroascorbate and that iron and H202 have the sole function of accelerating its formation.

Animals↗
PubMed1985

Analgesic activity of medroxyprogesterone acetate (MAP) in cancer patients: an antiinflammatory mediated activity?

When we initially used high doses of MAP (greater than 500 mg/day/im or greater than 2000 mg/day p.o.) in advanced cases of breast cancer, we noticed that, even before objective remission became apparent, the treatment induced subjective remission and a strong analgesic effect. Overall, our breast cancer patients treated with MAP at high doses (300 patients) showed a 65% incidence of pain relief. The analgesic effect of MAP does not seem to be closely related to its antitumour effect, because the same effect was also observed in patients with hormone-insensitive tumours. Our pharmacokinetic studies have demonstrated that it is important to use high doses in order to obtain high plasma levels. In order to clarify the mode of action of this MAP analgesy, hot-plate, tail-flick, Randall, writhing and carrageenin-oedema tests were carried out on rats. We found no evidence for central or peripheral analgesic activity, but there was evidence for an antiinflammatory activity of MAP.

Animals↗
PubMedDate not supplied

Rhodiola rosea as antioxidant in red blood cells: ultrastructural and hemolytic behaviour.

Rhodiola rosea L. (Crassulaceae) is a plant that lives at high altitude in Europe and Asia, widely used for its high capacity to increase the organism resistance to different stress conditions. Although a few international literature supports these effects, today R. rosea has become a common component of many dietary supplements also in the Western world. The aim of the present study was to investigate the effect of the R. rosea roots aqueous extract on in vitro human erythrocytes exposed to hypochlorous acid (HOCl)-oxidative stress. Several damages occur in human erythrocytes exposed in vitro to HOCl, among these membrane protein and lipid modifications, shifting from the discocyte shape to the echinocyte one, and determining lysis ultimately. Therefore, in the present work, the evaluation of the antioxidant capacity of the Rhodiola extract has been carried out by means of scanning electron microscopy and of hemolytic behaviour on human erythrocytes exposed to HOCl in the presence of increasing doses of the aqueous extract in different experimental environments (co-incubation and subsequent incubations). The results obtained are consistent with a significant protection of the extract in presence of the oxidative agent, but a cautionary note emerges from the analysis of the data related to the cell exposition to the plant extract in the absence of any induced oxidative stress. In fact, the addition to erythrocyte of high doses of R. rosea extract always determines severe alterations of the cell shape.

Antioxidants↗
PubMedDate not supplied

[Nutritional genomics: toward a personalized diet].

Nutrigenomics is the application of high-throughput genomics tools to the study of diet-gene interactions in order to identify dietetic components having beneficial or detrimental health effects. Nutrition becomes indeed one of the environmental factors influencing gene expression. We can consider nutrigenomics as a multidisciplinary science that comes after the human genome characterization and that put the genomic techniques besides the biochemical and epidemiological aspects, with the aim to understand the etiologic aspects of chronic diseases such as cancer, type 2 diabetes mellitus (T2DM), obesity, cardiovascular diseases (CVD), metabolic syndrome, etc. Nutrigenomics is linked to nutrigenetics, which studies the genetic basis of the different individual response to the same nutritional stimulus. This phenomenon arises from gene polymorphism. As a consequence genes are important in determining a function, but nutrition is able to modify the degree of gene expression. These are however theories only at an early stage, but a perspective in the change of dietetic intervention is emerging. A really personalized diet will be a diet considering the nutritional status, the nutritional needs based on age, body composition, work and physical activities, but also considering the genotype. The integration of all these information and in particular the ones arising from genomic, proteomic and metabolomic analyses will be useful to define the "nutritional phenotype".

Diet↗
PubMedDate not supplied

[The clinical significance of lymph node micrometastases and of concept of sentinel lymph node].

Micrometastases, (metastases smaller than 2 mm), had benn subject of several studies. In literature is documented a prognostic worsening due to their presence. Research of micrometastases in sentinel lymph node is of great interest and can allow a clinical application with profitable cost efficacy ratio. The Authors discuss about clinical, prognostical and therapeutical implicationes in case of micrometastases into sentinel lympho nodes.

Adenocarcinoma↗
PubMedDate not supplied

Oral versus intramuscular methotrexate in juvenile chronic arthritis. Italian Pediatric Rheumatology Study Group.

OBJECTIVE: To compare the efficacy and safety of methotrexate (MTX) after oral and intramuscular administration in children with juvenile chronic arthritis (JCA). METHODS: Pediatric rheumatology centers in Italy participated in this short-term, prospective, open trial. Each investigator was allowed to choose the oral or intramuscular route of administration according to his personal preference in everyday clinical practice. Patients enrolled by each center were given MTX through the same method of administration. All patients received 10 mg/m2 of MTX each week for six months. RESULTS: A total of 257 patients with JCA (127 treated orally and 130 intramuscularly) were enrolled in the trial by 11 Italian centers. The response rate after 6 months of MTX therapy was 58% in the oral and 61% in the intramuscular cohort. The frequency of adverse side effects did not differ significantly between the two treatment groups. CONCLUSION: The results of this study suggest that MTX at the conventional dose regimen is equally effective and has a similar safety profile in children with JCA when administered orally or by intramuscular injections.

Administration, Oral↗
PubMedDate not supplied

Erythema nodosum: a presenting sign of early onset sarcoidosis.

"Early onset sarcoidosis" is a chronic granulomatous disease occurring in children younger than 5 years of age, and characterized by a classic symptom triad consisting of skin, eye and joint lesions, with on rare occasion pulmonary involvement. The disorder often goes unrecognized because of its rarity and, since polyarthritis and uveitis are the predominant symptoms, most of these children are misdiagnosed as having juvenile chronic arthritis (JCA). A child with erythema nodosum at 7 months of age, later diagnosed as JCA and definitively recognized as "early onset sarcoidosis" is reported. This case shows that, whenever possible, a biopsy showing the typical picture of sarcoid granulomas is crucial to distinguish these clinical conditions.

Age of Onset↗