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C Grimaldi

Publications and source records attributed to C Grimaldi.

At least 19 recordsLinked to original sources
PubMed2006

Spin-Hall conductivity in electron-phonon coupled systems.

We derive the ac spin-Hall conductivity sigmasH(omega) of two-dimensional spin-orbit coupled systems interacting with dispersionless phonons of frequency omega0. For the linear Rashba model, we show that the electron-phonon contribution to the spin-vertex corrections breaks the universality of sigmasH(omega) at low frequencies and provides a nontrivial renormalization of the interband resonance. On the contrary, in a generalized Rashba model for which the spin-vertex contributions are absent, the coupling to the phonons enters only through the self-energy, leaving the low-frequency behavior of sigmasH(omega) unaffected by the electron-phonon interaction.

Journal Article↗
PubMed2006

The complete genome sequence of Lactobacillus bulgaricus reveals extensive and ongoing reductive evolution.

Lactobacillus delbrueckii ssp. bulgaricus (L. bulgaricus) is a representative of the group of lactic acid-producing bacteria, mainly known for its worldwide application in yogurt production. The genome sequence of this bacterium has been determined and shows the signs of ongoing specialization, with a substantial number of pseudogenes and incomplete metabolic pathways and relatively few regulatory functions. Several unique features of the L. bulgaricus genome support the hypothesis that the genome is in a phase of rapid evolution. (i) Exceptionally high numbers of rRNA and tRNA genes with regard to genome size may indicate that the L. bulgaricus genome has known a recent phase of important size reduction, in agreement with the observed high frequency of gene inactivation and elimination; (ii) a much higher GC content at codon position 3 than expected on the basis of the overall GC content suggests that the composition of the genome is evolving toward a higher GC content; and (iii) the presence of a 47.5-kbp inverted repeat in the replication termination region, an extremely rare feature in bacterial genomes, may be interpreted as a transient stage in genome evolution. The results indicate the adaptation of L. bulgaricus from a plant-associated habitat to the stable protein and lactose-rich milk environment through the loss of superfluous functions and protocooperation with Streptococcus thermophilus.

Bacterial Proteins↗
PubMed2006

Tunneling and nonuniversality in continuum percolation systems.

The values obtained experimentally for the conductivity critical exponent in numerous percolation systems, in which the interparticle conduction is by tunneling, were found to be in the range of t0 and about t0 + 10, where t0 is the universal conductivity exponent. These latter values are, however, considerably smaller than those predicted by the available "one-dimensional"-like theory of tunneling percolation. In this Letter, we show that this long-standing discrepancy can be resolved by considering the more realistic "three-dimensional" model and the limited proximity to the percolation threshold in all the many available experimental studies.

Journal Article↗
PubMed2005

Polaronic and nonadiabatic phase diagram from anomalous isotope effects.

Isotope effects (IEs) are powerful tools to probe directly the dependence of many physical properties on lattice dynamics. In this Letter we investigate the onset of anomalous IEs in the spinless Holstein model by employing the dynamical mean field theory. We show that the isotope coefficients of the electron effective mass and of the dressed phonon frequency are sizable also far away from the polaronic crossover and mark the importance of nonadiabatic lattice fluctuations. We draw a nonadiabatic phase diagram in which we identify a novel crossover, not related to polaronic features, where the IEs attain their largest anomalies.

Journal Article↗
PubMed2003

Differential sensitivity of human monocytes and macrophages to ANP: a role of intracellular pH on reactive oxygen species production through the phospholipase involvement.

Atrial natriuretic peptide (ANP), a cardiovascular hormone, elicits different biological actions in the immune system. The aim of the present work was to study the effect of ANP on the intracellular pH (pHi) of human monocytes and macrophages and to investigate whether pHi changes could play a role on phospholipase activities and reactive oxygen species (ROS) production. Human macrophages isolated by peripheral blood mononuclear cells and THP-1 monocytes, which were shown to express all three natriuretic peptide receptors (NPR-A, NPR-B, and NPR-C), were treated with physiological concentrations of ANP. A significant decrease of pHi was observed in ANP-treated macrophages with respect to untreated cells; this effect was paralleled by enhanced phospholipase activity and ROS production. Moreover, all assessed ANP effects seem to be mediated by the NPR-C. In contrast, no significant effect on pHi was observed in THP-1 monocytes treated with ANP. Treatment of macrophages or THP-1 monocytes with 5-(N-ethyl-N-isopropyl)amiloride, a specific Na(+)/H(+) antiport inhibitor, decreases pHi in macrophages and monocytes. Our results indicate that only macrophages respond to ANP in terms of pHi and ROS production, through diacylglycerol and phosphatidic acid involvement, pointing to ANP as a new modulator of ROS production in macrophages.

Amiloride↗
PubMed2002

High T(c) superconductivity in MgB2 by nonadiabatic pairing.

The evidence for the key role of the sigma bands in the electronic properties of MgB2 points to the possibility of nonadiabatic effects in the superconductivity of these materials. These are governed by the small value of the Fermi energy due to the vicinity of the hole doping level to the top of the sigma bands. We show that the nonadiabatic theory leads to a coherent interpretation of T(c) = 39 K and the boron isotope coefficient alphaB = 0.30 without invoking very large couplings and it naturally explains the role of the disorder on T(c). It also leads to various specific predictions for the properties of MgB2 and for the material optimization of these types of compounds.

Journal Article↗
PubMed2001

Transcriptional response of a human colon adenocarcinoma cell line to sodium butyrate.

Taking advantage of the DNA array screening technology, we analysed the effect of sodium butyrate on mRNA transcription in human HT29 colon adenocarcinoma cells. Out of 588 mRNA species analysed, only 119 resulted expressed. Among these, 60 exhibited a variable degree of modulation after butyrate treatment. Genes linked to the cell growth, apoptosis and oxidative metabolism appeared the most significantly affected. Furthermore, many of the differentially expressed genes are transcription factors and this may account for the variability of the biological effects of butyrate. The pattern of butyrate-affected genes may represent a reference in further analyses of gene expression of intestinal cells and tissues.

Adenocarcinoma↗
PubMed2001

Influence of timing of administration of 5-fluorouracil to donors on bone marrow engraftment in nonmyeloablated hosts.

We evaluated the engraftment and the cell cycle status of marrow cells at various times after 5-fluorouracil (5-FU) administration. 5-FU (150 mg/kg) was given to donor male BALB/c mice at 1, 2, 6, or 12 days prior to marrow harvest. The donor cells were then assessed in host nonmyeloablated female mice. Bone marrow engraftment of marrow treated with 5-FU was evaluated and compared to marrow treated with diluent (phosphate-buffered saline) at 3 and 10 weeks after marrow infusion. Our data show a rapid induction of an engraftment defect 1 day after 5-FU, persistence of this defect through day 6, and a recovery by day 12. Experiments using hydroxyurea (which selectively kills cells in the S phase) to determine the cell cycle status indicated that cells that engrafted in post-5-FU marrow were noncycling at days 1, 2, and 12 but cycling at day 6. Post-5-FU bone marrow was also analyzed in vitro by colony assays and its cycling status determined by 3H-thymidine suicide assay. High-proliferative-potential colony-forming cells (HPP-CFCs) and low-proliferative-potential colony-forming cells (LPP-CFCs) decreased rapidly 1 day after 5-FU, with a nadir observed at day 6 for HPP-CFCs and day 2 for LPP-CFCs. By day 12, LPP-CFCs showed a total recovery, but HPP-CFCs were still defective. Significant numbers of HPP-CFCs were cycling, mostly at days 6 and 8 after 5-FU, whereas LPP-CFCs appeared quiescent except at day 2. These results emphasize the importance of timing if post-5-FU marrow is used for gene therapy or marrow transplantation.

Animals↗
PubMed2001

The BRAVO project: screening for childhood obesity in a primary school setting.

BACKGROUND AND AIM: The prevalence of childhood obesity is increasing worldwide, raising a number of public health concerns. First, childhood obesity is a strong predictor of adult obesity; second, the low long term success rate and the high social cost of the treatment of obesity suggest that attention should be paid to the prevention of obesity early in childhood. The objective of the present study was to evaluate dietary habits and anthropometric factors in a sample of schoolchildren aged 6-12 years living in Southern Italy in the framework of an ongoing prospective study aimed at childhood obesity prevention. METHODS AND RESULTS: The BRAVO Project is carried out in co-operation with the school staff and is a part of an educational program on nutrition for the schoolchildren and their families. During the first phase of the study, the prevalence of overweight and obesity was evaluated in 363 children adopting the criteria for definition of childhood obesity recently proposed by the International Obesity Task Force (IOTF). The main result of this study was that in our cohort an exceedingly high risk of becoming overweight in adult age was observed for any one-year age class. CONCLUSIONS: The results of the present study confirmed the trend toward an increasing prevalence of childhood obesity observed in other Western countries. Moreover, out data--though preliminary--suggest that the large scale involvement of primary school in screening programs could represent an effective preventive strategy against the increased risk of childhood obesity.

Anthropometry↗
PubMed2000

Nonadiabatic channels in the superconducting pairing of fullerides

We show the intrinsic inconsistency of the conventional phonon mediated theory of superconductivity in relation to the observed properties of Rb3C60. The recent, highly accurate measurement of the carbon isotope coefficient alpha(C) = 0.21, together with the high value of T(c) (30 K) and the very small Fermi energy E(F) (0.25 eV), unavoidably implies the opening of nonadiabatic channels in the superconducting pairing. We estimate these effects and show that they are actually the key elements for the high value of T(c) in these materials compared to the very low values of graphite intercalation compounds.

Journal Article↗
PubMed2000

Genetic organization and polymorphism of the guaA gene encoding the GMP synthetase in Lactobacillus rhamnosus.

The guaA gene encoding GMP synthetase was cloned from a potential probiotic strain of Lactobacillus rhamnosus. DNA sequence and Northern blot analysis indicated that (i) guaA did not belong to an guaAB operonic structure, conversely to enteric bacteria, (ii) L. rhamnosus guaA seemed to be highly expressed, and (iii) genetic regulation might differ from Bacillus subtilis. Moreover, differences in the genetic organization of guaA allowed discrimination of some closely related L. rhamnosus strains, with a rapid screening by PCR.

Amino Acid Sequence↗
PubMed2000

Bromocriptine restores tolerance in estrogen-treated mice.

Estrogen can modulate autoimmunity in certain models of systemic lupus erythematosus. Recently, we have shown that it can mediate survival and activation of anti-DNA B cells in a mouse transgenic for the heavy chain of a pathogenic anti-DNA antibody. To identify whether estrogen effects reflect increased prolactin secretion, we characterized B-cell autoreactivity in transgenic mice given both bromocriptine (an inhibitor of prolactin secretion) and estradiol. Treatment of mice with estradiol plus bromocriptine led to reduced titers of anti-DNA antibodies and diminished IgG deposition in kidneys compared with treatment with estradiol alone. However, mice treated with estradiol plus bromocriptine showed an expansion of transgene-expressing B cells and enhanced Bcl-2 expression, similar to those of estradiol-treated mice. We identified anergic high-affinity anti-DNA B cells in mice treated with estradiol plus bromocriptine, and we showed by molecular analysis of anti-DNA hybridomas that their B cells derive from a naive repertoire. Thus, the estradiol-induced breakdown in B-cell tolerance can be abrogated by bromocriptine, which induces anergy in the high-affinity DNA-reactive B cells. These studies demonstrate that some of the effects of estrogen on naive autoreactive B cells require the presence of prolactin and, thus, suggest potential therapeutic interventions in lupus.

Animals↗
PubMed1998

Evaluation of antiandrogen therapy in unresectable hepatocellular carcinoma: results of a European Organization for Research and Treatment of Cancer multicentric double-blind trial.

PURPOSE: The aim of the study was to evaluate the efficacy of antiandrogen therapy on overall survival and response in unresectable hepatocellular carcinoma (HCC). PATIENTS AND METHODS: A total of 244 patients with unresectable HCC were included in this multicentric double-blind trial. According to a two-by-two factorial design, patients were randomly assigned to receive one of the following treatments: pure antiandrogen plus placebo (A+P group, 60 patients); luteinizing hormone-releasing hormone (LHRH) agonist plus placebo (LHRH+P group, 62 patients); pure antiandrogen plus LHRH agonist (A+LHRH group, 62 patients); or placebo plus placebo (P+P group, 60 patients). Pure antiandrogen consisted of Anandron (Roussel-Uclaf Laboratory, Romainville, France) administered orally (300 mg daily for 1 month, then 150 mg daily). LHRH consisted of goseriline acetate (3.6 mg) or triptoreline (3.75 mg) administered monthly by subcutaneous injection. Treatment was given until death. Response was evaluated every 8 weeks according to World Health Organization (WHO) criteria. RESULTS: Six patients were considered ineligible. One patient had a complete response (A+P arm) and three had a partial response (two in the LHRH+P arm and one in the A+LHRH arm). An overall log-rank test did not demonstrate any significant difference in survival among the four arms. Taking the factorial design into account, comparison of survival showed no significant difference between Anandron-containing regimens and others, or between LHRH-containing regimens and others. No serious side effects occurred for any regimen. CONCLUSION: This controlled study shows clearly the lack of efficacy of androgen treatment in unresectable HCC.

Androgen Antagonists↗
PubMed1998

Chiaroscuro hematopoietic stem cell.

These observations suggest several immediate clinical strategies. In gene therapy, approaches could be targeted to obtain cycling of hematopoietic stem cells and gene-carrying retrovirus vector integration followed by engraftment at an appropriate time interval which favors engraftment. The same type of approach can be utilized for stem cell expansion approaches. Alternatively marrow or peripheral stem cell engraftment can be obtained with minimal to no toxicity in allochimeric strategies in such diseases as sickle cell anemia or thalassemia. A similar approach could be useful in obtaining cell engraftment with minimal toxicity in therapies employing cellular immune (T-cell and NK-cell) attack against cancer. These areas of clinical application are outline in Table 3.

Animals↗
PubMed1996

Nutritional and prognostic correlates of bioimpedance indexes in hemodialysis patients.

We carried out a cross sectional and longitudinal study to assess whether bioimpedance indexes (resistance, Rz; reactance, Xc; phase angle, PA) reflect the nutritional status of hemodialysis (HD) patients, and bear a significant association with their long-term survival. The bioimpedance data of 131 patients on chronic HD treatment were compared with those of 272 healthy controls matched for age and sex. Nutritional status was assessed by anthropometric variables, serum albumin (SA), normalized protein catabolic rate (nPCR), and subjective global assessment (SGA). All three bioimpedance indexes varied significantly with HD treatment, however, with the exception of Xc in post-HD, they were on average significantly (P < 0.016) different from controls either pre- and post-HD. Post-HD PA appeared to be the best index of nutritional status, being significantly correlated with SA, age, mid arm muscle circumference (MAMC), SGA, and nPCR (R2 = 0.44; P < 0.01). However, depending on the cut-off levels, PA failed to detect clinically overt malnutrition in one to two thirds of the patients with the worst SGA score. During the follow-up the changes in bioimpedance indexes reflected poorly the changes in dry blood weight, only delta Rz bore a significant correlation (r = 0.29; P < 0.01) with delta body wt. Patients having baseline phase angle values within the lower quartile had a significantly lower two-year survival rate than patients having higher values (59.3% vs. 91.3%; P < 0.01). Cox's analysis (proportional hazard model) showed that phase angle as a predictor of death outweighed all other parameters included in the model (age, SA, nPCR, MAMC, SGA), with a relative risk of 2.6 (95% CI = 1.6 to 4.2). Bioimpedance indexes do not appear to be reliable in detecting clinically overt depletion of lean body mass. However, the strong association of PA with patient survival suggests that this bioimpedance index reflects some dimension of the illness, which is not fully identifiable with the deranged nutritional status.

Adult↗