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B Mantovani

Publications and source records attributed to B Mantovani.

At least 19 recordsLinked to original sources
PubMed2005

Molecular characterization of Tunga trimamillata and T. penetrans (Insecta, Siphonaptera, Tungidae): taxonomy and genetic variability.

A new species of the genus Tungo, T. trimamillata has recently been described on the basis of several morphological traits. To explore the taxonomic status of this flea with respect to T. penetrans, we undertook a molecular analysis of cytochrome oxydase II and 16S rDNA mitochondrial genes and of the internal transcribed spacer 2 nuclear marker on samples of both species. Maximum Parsimony evaluations of the three data set indicate a differentiation compatible with a specific rank between the two fleas with very high levels of divergence. Both mitochondrial and nuclear data are in line with a recent bottleneck in the Malagasy population of T. penetrans, possibly due to the recent colonisation of Africa via human transportation. Further, significantly lower mitochondrial variability in the Ecuadorian populations of T. penetrans with respect to the T. trimamillata ones is also evidenced.

Amino Acid Sequence↗
PubMed2003

The role of complement in the modulation by fluid-phase IgG of the production of reactive oxygen species by polymorphonuclear leukocytes stimulated with IgG immune complexes.

The production of reactive oxygen species (ROS) by polymorphonuclear leukocytes (PMN) can be induced by immune complexes and is an important component of phagocytosis in the killing of microorganisms, but can also be involved in inflammatory reactions when immune complexes are deposited in tissues. We have observed that fluid-phase IgG can inhibit the generation of ROS by rabbit PMN stimulated with precipitated immune complexes of IgG (ICIgG) in a dose-dependent manner, acting as a modulatory factor in the range of physiological IgG concentrations. This inhibitory effect is compatible with the known affinity (Kd) of monomeric IgG for the receptors involved (FcRII and FcRIII). The presence of complement components in the immune complexes results in a higher stimulation of ROS production. In this case, however, there is no inhibition by fluid-phase IgG. The effect of complement is strongly dependent on the presence of divalent cations (Ca2+ or Mg2+) in the medium, whereas the stimulation of ICIgG (without complement) does not depend on these cations. We have obtained some evidence indicating that iC3b should be the component involved in the effect of complement through interaction with the CR3 receptor. The absence of the inhibitory effect of fluid-phase IgG in ROS production when complement is present in the immune complex shows that complement may be important in vivo not only in the production of chemotactic factors for PMN, but also in the next phase of the process, i.e., the generation of ROS.

Animals↗
PubMed2002

Phagocytosis by macrophages mediated by receptors for denatured proteins - dependence on tyrosine protein kinases.

Previous studies have demonstrated that some components of the leukocyte cell membrane, CR3 (Mac-1, CD11b/CD18) and p150/95, are able to bind to denatured proteins. Thus, it is of interest to know which effector functions of these cells can be triggered by these receptors when they interact with particles or surfaces covered with denatured proteins. In the present study we analyzed their possible role as mediators of phagocytosis of red cells covered with denatured bovine serum albumin (BSA) by mouse peritoneal macrophages. We observed that a) macrophages are able to recognize (bind to) these red cells, b) this interaction can be inhibited by denatured BSA in the fluid phase, c) there is no phagocytosis of these particles by normal macrophages, d) phagocytosis mediated by denatured BSA can be, however, effectively triggered in inflammatory macrophages induced by glycogen or in macrophages activated in vivo with LPS, and e) this phagocytic capacity is strongly dependent on the activity of tyrosine protein kinases in its signal transduction pathway, as demonstrated by using three kinds of enzyme inhibitors (genistein, quercetin and herbimycin A).

Animals↗
PubMed2001

The mitochondrial cytochrome oxidase II gene in Bacillus stick insects: ancestry of hybrids, androgenesis, and phylogenetic relationships.

Sequencing of a cytochrome oxidase II (COII) gene fragment in Bacillus taxa provided evidence that the bisexual B. rossius is the maternal ancestor of the hybridogenetic B. rossius-grandii strains and revealed the same ancestry for both parthenogenetic hybrids: the diploid B. whitei (B. rossius/grandii grandii) and the triploid B. lynceorum (B. rossius/grandii grandii/atticus). Present data clearly demonstrate that all Bacillus unisexuals arose through asymmetrical hybridization events and realized a paraphyletic derivation from the B. rossius redtenbacheri subspecies. The invention of B. rossius mitochondrial DNA haplotypes in specimens with B. grandii grandii nuclear genomes revealed the occurrence of androgenesis in nature. Natural androgens represent a peculiar escape from hybridity and can help maintain the hybridogenetic system through the production of the fathering taxon via hybrid females. Results from the COII gene support the phyletic relationships among taxa suggested by previous taxonomical approaches, but also indicate a departure of B. grandii subspecies from the established taxonomy. Assuming the existence of a molecular clock, the evaluated substitution rate brings the splitting between B. rossius and B. grandii/B. atticus back to 22.79 +/- 2.65 myr before present, while the origin of hybrids appears to be much more recent (1.06 +/- 0.53 myr).

Androgens↗
PubMed1998

Satellite sequence turnover in parthenogenetic systems: the apomictic triploid hybrid Bacillus lynceorum (Insecta, Phasmatodea).

In the genus Bacillus (Insecta, Phasmatodea) the Bag320 satellite DNA family is present in the bisexual B. grandii and in the related automictic nonhybrid B. atticus; it is lacking in the other bisexual taxon of the genus, B. rossius. This family of highly repeated sequences was analyzed for 11 populations of the apomictic triploid hybrid B. lynceorum. In the neighbor-joining dendrogram, B. lynceorum nucleotide sequences distribute, regardless of geographical origin, among two clusters, one also including all clones of the three B. atticus races, and the other including sequences of the B. grandii grandii subspecies. Thus, B. lynceorum is a trihybrid taxon: as the molecular approach definitively demonstrates, it embodies one haploid complement each of both B. grandii grandii and B. atticus, which must be added to that of B. rossius. The contribution of the latter species has already been assessed on karyological and allozymic grounds. A statistical analysis performed on p-distances shows that for the parental taxa, nucleotide substitution values are of comparable magnitudes at the population level but differ at the subspecific level, being higher for the bisexual taxon. In the apomictic hybrid, atticus- and grandii grandii- like sequences coexist with significantly different p-distance values. For three clones, the nucleotide compositions at the diagnostic loci suggest that gene conversion can occur between atticus- and grandii grandii-like monomers. On the whole, this supports bisexuality as a driving force in variant fixation and suggests that in Bacillus, different gametogenetic processes and different origins of the unisexuals are mirrored in genomic turnover rates of satellite DNA.

Africa, Northern↗
PubMed1998

Precipitated immune complexes of IgM induce the generation of reactive oxygen species by rabbit polymorphonuclear leucocytes.

We report that immune complexes of IgM (ICIgM) antibodies and ovalbumin in the form of a precipitate from the equivalence zone induce the generation of reactive oxygen species by rabbit blood polymorphonuclear leucocytes (PMN), as measured by the chemiluminescence (CL) production in the presence of luminol. The kinetics of CL generation induced by ICIgM is quite different from that induced by precipitated immune complexes of IgG (ICIgG): the maximum rate of CL production for ICIgM occurs around 14 min, whereas for ICIgG it occurs about 5 min after incubation with the cells. Also the triggering of the process requires a higher concentration of ICIgM than of ICIgG. Evidence is presented that these effects are not mediated by interaction of the antigen (ovalbumin) with the cell, since immune precipitates of ovalbumin and the F(ab')2 fragment had no effect. Our observations that precipitated ICIgM can also be an effective stimulus for CL generation and thus for O2- production reveal a new functional capability of PMN. These results may have implications for the understanding of the participation of ICIgM (as well as of ICIgG) in inflammatory reactions mediated by PMN in immune complex diseases, and in the mechanisms of defense against microbes and other non-self agents.

Animals↗
PubMed1997

Latrunculin A is a potent inducer of aggregation of polymorphonuclear leukocytes.

We have shown that latrunculin A, a toxin from a Red Sea sponge which has striking effects in several phenomena dependent on the cytoskeleton, is a potent inducer of aggregation of rabbit polymorphonuclear leukocytes in a dose- and time-dependent manner. From 12 nM to 60 nM toxin the degree of aggregation (after 8 min) in nearly directly proportional to the toxin concentration; the aggregation effect is energy-dependent from the glycolytic pathway. It was also shown that 120 nM latrunculin A, after 5 min incubation, can reduce to more than half the F-actin percent of the leucocytes. These results may contribute to the study of the relations between the actin cytoskeleton of leukocytes and the process of aggregation which is involved in important physiological functions of these cells.

Actins↗
PubMed1997

The Bag320 satellite DNA family in Bacillus stick insects (Phasmatodea): different rates of molecular evolution of highly repetitive DNA in bisexual and parthenogenic taxa.

The Bag320 satellite DNA (satDNA) family was studied in seven populations of the stick insects Bacillus atticus (parthenogenetic, unisexual) and Bacillus grandii (bisexual). It was characterized as widespread in all zymoraces of B. atticus and in all subspecies of B. grandii. The copy number of this satellite is higher in the bisexual B. grandii (15%-20% of the genome) than in the parthenogenetic B. atticus (2%-5% of the genome). The nucleotide sequences of 12 Bag320 clones from B. atticus and 17 from B. grandii differed at 13 characteristic positions by fixed nucleotide substitutions. Thus, nucleotide sequences from both species cluster conspecifically in phylogenetic dendrograms. The nucleotide sequences derived from B. grandii grandii could be clearly discriminated from those of B. grandii benazzii and B. grandii maretimi on the basis of 25 variable sites, although all taxa come from Sicily. In contrast, the Bag320 sequences from B. atticus could not be discriminated accordingly, although they derive from geographically quite distant populations of its three zymoraces (the Italian and Greek B. atticus atticus, the Greek and Turkish B. atticus carius, and the Cyprian B. atticus cyprius). The different rate of evolutionary turnover of the Bag320 satDNA in both species can be related to their different modes of reproduction. This indicates that meiosis and chromosome segregation affect processes in satDNA diversification.

Animals↗
PubMed1997

Systemic clotting activation by low-grade endotoxaemia in liver cirrhosis: a potential role for endothelial procoagulant activation.

BACKGROUND: The pathophysiologic mechanism underlying the association between endotoxaemia and clotting activation in liver cirrhosis is still to be explained. AIMS: To investigate the relationship between endotoxaemia, endothelial perturbation and clotting system activation in liver cirrhosis patients. PATIENTS: The study was carried out in 30 consecutive patients (17 males, 13 females, age range 42 to 71 years) with liver cirrhosis. METHODS: Prothrombin fragment F1 + 2, endotoxaemia, von Willebrand factor and ristocetin cofactor activity were studied in all patients. Von Willebrand factor antigen release and tissue factor expression were also evaluated in cultured endothelial cells incubated with low endotoxin concentrations (125-500 pg/ml). RESULTS: Thirteen (43%) out of 30 liver cirrhosis patients showing von Willebrand factor antigen levels > 157 IU/dl (mean +/- 2SD of controls) were considered to have signs of endothelial perturbation; they had more severe liver failure (p = 0.0001), higher ristocetin cofactor activity (p = 0.0001), endotoxin (p = 0.0001) and prothrombin fragment F1 + 2 (p = 0.0001) plasma values than liver cirrhosis with normal von Willebrand factor antigen. A strong correlation (r = 0.97; p = 0.0001) was found between prothrombin fragment F1 + 2 and von Willebrand factor antigen. In in vitro experiments endotoxin induced a concentration-dependent release of von Willebrand factor antigen (p = 0.0001) and expression of tissue factor activity (p = 0.0001) and antigen (p = 0.0001) from cultured endothelial cells. CONCLUSIONS: This study suggests that the endothelial procoagulant activation induced by low-grade endotoxaemia may represent a trigger for systemic clotting activation in liver cirrhosis patients.

Adult↗
PubMed1996

Effects of latrunculin A on immunological phagocytosis and macrophage spreading-associated changes in the F-actin/G-actin content of the cells.

Latrunculin A, a toxin from a Red Sea sponge, was shown to be a very potent inhibitor of immunological phagocytosis by normal and activated macrophages (obtained from mice injected i.p. with LPS), as well as by polymorphonuclear leukocytes. This toxin blocks the interiorization of the immune complexes but does not interfere with their binding to the phagocyte (recognition phase); activated macrophages were more susceptible to this inhibition than normal macrophages and polymorphonuclear leukocytes. The effect of the toxin on cellular spreading of macrophages was also studied using two kinds of substrate: glass, and glass covered with IgG immune complexes. Latrunculin A was able to impair the spreading of normal macrophages on glass covered with immune complexes, and could also completely reverse the spreading after it had occurred. Contrarily, in activated macrophages, this toxin could neither impede the spreading nor reverse it, a difference that might be a distinctive property of the activated state. We have also found that latrunculin A can reduce the percentage of F-actin in both normal and activated macrophages, the activated cells being more susceptible to this effect. Since latrunculin A is a blocking agent of actin polymerization in vitro, these results indicate that actin polymerization and assembly must be an essential component of the primary, active event of the engulfment phase of phagocytosis.

Actins↗
PubMed1993

Genetic structure and phyletic relationships of eastern Mediterranean Bacillus atticus brunner (Insecta Phasmatodea): a biochemical study.

The allozymic characterization of several new Croatian, Greek, and Turkish samples thought to belong to different subspecies of Bacillus atticus or to atticus-like taxa is given. Several allelic combinations (zymotypes) were observed among both diploid and triploid samples; the occurrence of highly different levels of heterozygosity for the same locus among populations is also common. The biochemical-genetic features of the numerous zymotypes are interpreted on the basis of the recently assessed cytology of their parthenogenetic reproduction. Biochemical and meiotic features also allow one to suggest that both diploid and triploid cytotypes of B. atticus are more likely interracial hybrids in origin. The new triploid Greek samples show only small genetic distances from the Turkish triploid and diploid ones; also, they do not show clear-cut morphological differences, so that all triploids and Turkish diploid samples are together referred to as B. a. carius. On the other hand, all Croatian, Greek, and Italian diploids appear to belong to the same electrophoretic cluster, biochemically differentiated at a subspecific level from B. a. carious. This newly defined comprehensive group of diploid samples, which also morphologically show gradual patterns of variation, is referred to as B. a. atticus.

Animals↗
PubMed1993

A centromeric satellite DNA of the unisexual Bacillus atticus (Insecta: Phasmatodea).

In the parthenogenetic Bacillus atticus atticus, widespread over most of the Mediterranean basin, a highly repeated satellite DNA (BaB300) has been detected and analysed. BgI II, Taq I and Alu I restriction enzymes cut 316 bp long repeating units from the BaB300 family. These are non-coding, AT rich and well conserved in the three isolated populations studied. By in situ hybridization, the satellite has been located in the centromeric heterochromatin of a subset of medium- and small-sized chromosomes, including the Xs. Related sequences have been found in the bisexual B. grandii grandii and in its specific hybrid B. whitei (=B. rossius/grandii grandii), while they are absent from B. rossius redtenbacheri. These data support the genetic affinity relationships within the genus Bacillus inferred from morphological, allozymic and karyological data. They also encourage further comparisons among Bacillus hybrids, in order to trace their parental genomes in the hybrid nuclei, and within the B. atticus complex (i.e. additional samples of B. a. atticus and diploid/triploid cytotypes of B. a. carius) to study repetitive DNA turnover in unisexual organisms.

Animals↗
PubMed1992

Precipitated immune complexes of IgM as well as of IgG can bind to rabbit polymorphonuclear leucocytes but only the immune complexes of IgG are readily phagocytosed.

We have shown by in vitro experiments, using immunofluorescence techniques, that precipitated immune complexes of IgM antibodies and ovalbumin (ICIgM) are able to bind to rabbit blood polymorphonuclear leucocytes (PMN), as well as immune complexes of IgG antibodies (ICIgG). This binding capacity for both classes of immune complexes is exhibited by more than 80% of the PMN cell population and is independent of Ca2+ in the medium. For ICIgG the binding to PMN can be completely inhibited by preincubation of the cells with soluble IgG used at physiological concentrations (competition for the Fc gamma receptors) while for ICIgM there is no such inhibition by fluid-phase IgM. After binding to the leucocytes there was a striking difference in the fate of ICIgM and ICIgG: whereas the ICIgG was readily phagocytosed (endocytosed), the ICIgM remained mostly on the cell surface, being only poorly endocytosed after 1 hr incubation at 37 degrees. This was demonstrated by a quantitative fluorimetric method developed to assay phagocytosis of immune complexes, and was confirmed by a qualitative fluorescence quenching technique. These results may have implications for understanding the fate of these classes of immune complexes formed in circulation or deposited in tissues, and the participation of PMN in inflammatory reactions and tissue injury in immune complex diseases.

Animals↗
PubMed1990

Ketoconazole therapy for women with acne and/or hirsutism.

The effects of ketoconazole, a synthetic imidazole derivate, were evaluated in 42 women affected by acne (17 cases) and/or hirsutism (36 cases) treated with 400 mg/day for 3-6 months. Androstenedione, total and free testosterone, 5 alpha dihydrotestosterone and dehydroepiandrosterone levels progressively dropped during treatment while 17 alpha hydroxyprogesterone, estradiol, ACTH, cortisol, LH and FSH levels increased. Dehydroepiandrosterone sulfate decreased only towards the end of treatment, while estrone, sex hormone binding globulin, and PRL remained unchanged. Daily mean +/- SD rate of hair growth, measured by a special image analysis processor, decreased within 3 months of therapy from 0.258 +/- 0.058 to 0.184 +/- 0.039 mm/day (P less than 0.02) and mean +/- SD hair diameter from 0.123 +/- 0.015 to 0.110 +/- 0.013 mm (P less than 0.05) together with decreasing hormone levels. The therapeutic effects of ketoconazole on hirsutism was evident at 6 months in only 14 subjects, while no significant change in hirsutism score was recorded in 22 women who failed to complete the therapy. Acne improved in all cases. Several side effects and complications arose during treatment, such as headache, nausea, loss of scalp hair, hepatitis, and biochemical changes. Even though ketoconazole improves hyperandrogenism, only selected patients are eligible for treatment as scrupulous monitoring is required.

Acne Vulgaris↗
PubMed1988

Latrunculin A is a potent inhibitor of phagocytosis by macrophages.

We have found that latrunculin A, a Red Sea sponge toxin, is a potent inhibitor of immunological phagocytosis by mouse peritoneal macrophages, but does not block the binding (recognition) of the immune complexes (erythrocytes sensitized with IgG antibodies) to the cells. The inhibition begins to be appreciable around 12 nM latrunculin A, and is complete with a toxin concentration of 60 nM. This inhibitory effect does not interfere with the cell viability, and can be reversed when the macrophages are incubated in fresh medium. Since latrunculin A is a disrupting agent of microfilament organization, these results strengthen the evidence for the active participation of microfilaments in the mechanism of phagocytosis and at the same time provide a new tool for the investigation of phagocytosis at the molecular level.

Actin Cytoskeleton↗
PubMed1988

The role of complement in the stimulation of lysosomal enzyme release by polymorphonuclear leucocytes induced by immune complexes of IgG and of IgM.

The effect of complement components incorporated into precipitated immune complexes (IC) of IgG or of IgM on their capacity for stimulating lysosomal enzyme release from rabbit polymorphonuclear leucocytes was studied in vitro. We have found that: (i) complement causes an amplification in the stimulatory capacity of both classes of IC, the effect being dependent on the concentration of the IC, and higher for the IgM class; (ii) dose-effect experiments of competition by fluid-phase immunoglobulins have shown that IgG (in physiological or smaller concentrations) can inhibit greatly the stimulation by this class of immune complex; this inhibition can be prevented, however, by the presence of complement in the IC (a situation expected to occur in vivo); for IgM immune complexes there was no such competitive inhibition, so complement would not be necessary; (iii) the relevant complement factors must be located in the range C1-C3. These results help us to understand the importance of complement (besides the well-known generation of chemotactic factors) in the mechanisms of tissue injury produced by neutrophils in immune complex diseases.

Animals↗