PubMed Health⌕ Search

Biomedical subjects

A Paoletti

Publications and source records attributed to A Paoletti.

At least 19 recordsLinked to original sources
PubMed2005

Performance indicators for the efficiency analysis of urban drainage systems.

Performance indicators implemented in a decision support system (DSS) for the technical, managerial and economic evaluation of urban drainage systems (UDS), called MOMA FD, are presented. Several kinds of information are collected and processed by MOMA FD to evaluate both present situation and future scenarios of development and enhancement. Particular interest is focused on the evaluation of the environmental impact, which is considered a very relevant factor in the decision making process to identify the priorities for UDS improvements.

Cities↗
PubMed2004

Development and application of CVD diamond detectors to 14 MeV neutron flux monitoring.

CVD diamond is an interesting material for radiation detection, its atomic number (Z = 6) is close to that of soft tissues (Z = 7.1) and it can also work in harsh environments. Since many years CVD diamond films have been grown at the Faculty of Engineering, Rome 'Tor Vergata' University, and in 1998 a collaboration with ENEA Fusion Division was established to develop fast neutron monitors to be used in fusion tokamak environment. In this paper the first test of a 120 microm thick polycrystalline CVD diamond detector used for monitoring 14.7 MeV neutrons emission produced with the Frascati Neutron Generator (FNG) is reported. The detector operates in air and in pulse mode. The time irradiation profiles recorded with the CVD diamond detector were compared with those recorded by the standard monitors available at FNG (SSD, fission chamber, NE-213). Good stability and capability to operate in neutron flux up to 1.5 x 10(8) n cm(-2) s(-1) was observed. The radiation hardness property was also investigated using a 460 microm thick film and these results are also reported.

Diamond↗
PubMed2001

Evidence that the HIV-1 coat protein gp120 causes neuronal apoptosis in the neocortex of rat via a mechanism involving CXCR4 chemokine receptor.

The HIV-1 coat protein, gp120 (100 ng given intracerebroventricularly (i.c.v.) daily for seven consecutive days) causes DNA fragmentation in the brain neocortex of rat. In neocortical cells bearing ultrastructural features typical of apoptosis, electron microscopy revealed specific immunopositivity for neurofilament cytoskeletal proteins, suggesting the neuronal nature of dying cells. Neuronal apoptosis by gp120 implicates CXCR4 chemokine receptors; in fact, in rats receiving a single daily, non-neurotoxic, dose of SDF-1alpha (0.25 pmoles given i.c.v. for 7 days before gp120), the natural ligand of CXCR4 receptor, apoptosis was significantly hindered. The mechanism of SDF-1alpha protection involves inhibition of gp120-enhanced expression of IL-1beta, a cytokine implicated in the mechanisms of apoptosis induced by the viral protein in the neocortex of rat.

AIDS Dementia Complex↗
PubMed2000

A role for centrin 3 in centrosome reproduction.

Centrosome reproduction by duplication is essential for the bipolarity of cell division, but the molecular basis of this process is still unknown. Mutations in Saccharomyces cerevisiae CDC31 gene prevent the duplication of the spindle pole body (SPB). The product of this gene belongs to the calmodulin super-family and is concentrated at the half bridge of the SPB. We present a functional analysis of HsCEN3, a human centrin gene closely related to the CDC31 gene. Transient overexpression of wild-type or mutant forms of HsCen3p in human cells demonstrates that centriole localization depends on a functional fourth EF-hand, but does not produce mitotic phenotype. However, injection of recombinant HsCen3p or of RNA encoding HsCen3p in one blastomere of two-cell stage Xenopus laevis embryos resulted in undercleavage and inhibition of centrosome duplication. Furthermore, HsCEN3 does not complement mutations or deletion of CDC31 in S. cerevisiae, but specifically blocks SPB duplication, indicating that the human protein acts as a dominant negative mutant of CDC31. Several lines of evidence indicate that HsCen3p acts by titrating Cdc31p-binding protein(s). Our results demonstrate that, in spite of the large differences in centrosome structure among widely divergent species, the centrosome pathway of reproduction is conserved.

Animals↗
PubMed2000

Analysis of mid1p, a protein required for placement of the cell division site, reveals a link between the nucleus and the cell surface in fission yeast.

mid1 is required for the proper placement of the contractile actin ring for cytokinesis at a medial site overlying the nucleus. Here we find that mid1 protein (mid1p) shuttles between the nucleus and a cortical medial broad band during interphase and early mitosis. The position of this broad band, which overlies the nucleus, is linked to nuclear position even in cells with displaced or multiple nuclei. We identified and created mutations in an NLS and in two crm1-dependent NES sequences in mid1p. NES mutations caused mid1p accumulation in the nucleus and loss of function. An NLS mutations greatly reduced nuclear localization but did not perturb cytoplasmic localization or function. mid1p localization to the medial broad band was also not dependent on mid1p PH domain or microtubule and actin cytoskeletons. Overexpression of mid1p produced ectopic cell growth at this band during interphase and abnormal karmellae-like nuclear membrane structures. In plo1-1, mid1p formed a medial broad band but did not incorporate into a tight ring, suggesting that polo kinase plo1p is required for activation of mid1p function. Thus, the mid1p broad band defines a compartment at the medial cell surface, whose localization is linked to the position of the nucleus, and whose function may be to position the plane of cell division.

Actins↗
PubMed1997

Identification of a new mammalian centrin gene, more closely related to Saccharomyces cerevisiae CDC31 gene.

Among the numerous centrin isoforms identified by two-dimensional gel electrophoresis in human cells, an acidic and slow-migrating isoform is particularly enriched in a centrosome fraction. We report here that this isoform specifically reacts with antibodies raised against Saccharomyces cerevisiae Cdc31p and is present, as other centrin isoforms, in the distal lumen of centrioles. It is encoded by a new centrin gene, which we propose to name HsCEN3 (Homo sapiens centrin gene 3). This gene is more closely related to the yeast CDC31 gene, and shares less identity with algae centrin than HsCEN1 and HsCEN2. A murine CDC31-related gene was also found that shows 98% identity and 100% similarity with HsCEN3, demonstrating a higher interspecies conservation than the murine centrin gene MmCEN1 (Mus musculus centrin gene 1) with either HsCEN1, or HsCEN2. Finally, immunological data suggest that a CDC31-related gene could exist in amphibians and echinoderms as well. All together, our data suggest the existence of two divergent protein subfamilies in the current centrin family, which might be involved in distinct centrosome-associated functions. The possible implication of this new mammalian centrin gene in centrosome duplication is discussed.

Amino Acid Sequence↗
PubMed1997

Organisation and functional regulation of the centrosome in animal cells.

Molecular characterisation of centrosomal components is slowly progressing. Recent results indicate that the major aspects of centrosome-mediated microtubule nucleation may soon be understood at the molecular level. In contrast, centrosome reproduction, which is an important aspect of animal cell division, remains terra incognita. The most challenging issue for the future is to understand the molecular mechanisms which control centrosome biogenesis. There is a urgent need to identify with certainty proteins implicated in this process. Comparison between organisms with structurally different centrosomes might be critical for a better understanding of centrosome duplication if a general mechanism has been conserved throughout evolution.

Animals↗
PubMed1997

Antibody prevents the establishment of persistent arenavirus infection in synergy with endogenous T cells.

A cardinal feature of the biology of lymphocytic choriomeningitis virus (LCMV) is its ability to establish persistent infections in mice. Persistence is usually established by infection of the mouse during the in utero or neonatal period. Susceptibility can be extended to the adult by treatment with immunosuppressive agents or by infection with immunosuppressive strains of LCMV. In this study we investigated the capacity of passively acquired anti-LCMV antibodies to prevent the establishment of persistence in both neonatal and adult mice. Suckling BALB/c mouse pups nursed by mothers immunized against LCMV before pregnancy had higher survival rates following infection than controls and withstood challenge doses of up to 400 PFU without becoming persistently infected. To establish that maternal antibody alone and not maternally derived T cells provided this protection, nonimmune mothers were infused with monoclonal anti-LCMV neutralizing antibodies within 24 h after delivering their pups. Pups nursing on these passively immunized mothers were resistant to persistent LCMV infection. The establishment of persistence in adult BALB/c mice by the immunosuppressive, macrophage-tropic LCMV variant, clone 13 was also prevented by prophylactic treatment with anti-LCMV monoclonal antibodies. However, the protection afforded by passively acquired antibody was found to be incomplete if the recipients lacked functional CD8+ T cells. While 65% of neonatal athymic (nu/nu) mice nursed by immune nu/+ dams resisted low-dose viral challenge (25 PFU), the majority of nude pups challenged with high doses of virus (100 PFU) became persistently infected. Also, protection was incomplete in beta2-microglobulin knockout mice, which lack functional CD8+ T cells, suggesting that a cooperative effect was exerted by the combination of neutralizing antibody and endogenous T cells. These results indicate that antibodies provide an effective barrier to the establishment of persistent infections in immunocompetent mice and reaffirm that vaccines which induce strong humoral responses may provide efficient protection against arenavirus infections.

Animals↗
PubMed1997

Pulse treatment of interphasic HeLa cells with nanomolar doses of docetaxel affects centrosome organization and leads to catastrophic exit of mitosis.

In order to investigate the role of centrosome duplication in mitotic spindle morphogenesis, we designed a 1 hour pulse treatment protocol on synchronized HeLa cells with nanomolar doses of taxoids that might impair centrosome biogenesis but would allow the recovery of normal microtubule (Mt) dynamics before mitosis. We were prompted to use this approach as docetaxel (DOC; taxotereTM), a taxoid known to promote Mt polymerization, was shown to be more cytotoxic when applied during S phase. We show that pulse drug exposure is most efficient in late S and in G2 and results in a marked disorganization of the centrosome in G2, the pericentriolar material (PCM) being dissociated from centrioles. Separation of centrosomes at the G2-M transition is also impaired and mitotic spindle morphogenesis is grossly abnormal: although in most spindles chromosomes align in a metaphase plate, the two centrosomes stay most often unseparated at one pole and most of the NuMA protein accumulates at the other. Interestingly, we find that the centrosomes' ability to duplicate is not abolished as they are still able to trigger parthenogenetic development of frog eggs. Despite spindle asymmetry, the progression through mitosis is not blocked. This results in a catastrophic exit from mitosis, each mitotic cell generating several micronucleated cells linked together by multiple midbodies. Lack of mitotic block appears therefore as the prime cause of cell lethality. These experiments suggest that NuMA redistribution at the onset of mitosis depends upon the correct redistribution of PCM between centriole pairs. They also indicate that the presence of aberrant spindle poles does not alert the surveillance mechanism controlling the exit of mitosis.

Animals↗
PubMed1996

Most of centrin in animal cells is not centrosome-associated and centrosomal centrin is confined to the distal lumen of centrioles.

Centrin is a member of the calcium-binding EF-hand protein superfamily present in centrosomes of widely divergent species. Investigating the cellular distribution of human centrin by both immunofluorescence and cell fractionation, we report that centrin is biochemically complex in human cells, displaying as much as ten isoforms in 2-D electrophoresis. This suggests that centrin may be subject to multiple regulations. Strikingly, more than 90% of centrin is not associated with the centrosome fraction. The centrosome-associated centrin, however, displays a specific pattern in 2-D electrophoresis and is concentrated within the distal lumen of the centrioles, where a complex structure has been previously described. This precise localization allows the resolution of centrioles at the optical level throughout the cell cycle and provides a valuable tool for monitoring centriole duplication. To get insights on centrin function, we performed injection experiments of recombinant heterologous centrin in two-cell stage frog embryos in an attempt to produce dominant negative effects. We report that green algae and human centrin delay cleavage and promote the formation of abnormal blastomeres in which the distribution of microtubule asters and of nuclei is dramatically impaired. This suggests that centrin could be involved in the centrosome reproduction cycle, in the coordination of cytoplasmic and nuclear division or in cytokinesis.

Animals↗
PubMed1995

Actin-based movement of Listeria monocytogenes: actin assembly results from the local maintenance of uncapped filament barbed ends at the bacterium surface.

The thermodynamic basis for actin-based motility of Listeria monocytogenes has been investigated using cytoplasmic extracts of Xenopus eggs, initially developed by Theriot et al. (Theriot, J. A., J. Rosenblatt, D. A. Portnoy, P. J. Goldschmidt-Clermont, and T. J. Mitchison. 1994. Cell. 76:505-517) as an in vitro cell-free system. A large proportion (75%) of actin was found unpolymerized in the extracts. The amount of unassembled actin (12 microM) is accounted for by the sequestering functions of T beta 4Xen (20 microM) and profilin (5 microM), the barbed ends being capped. Movement of Listeria was not abolished by depletion of over 99% of the endogenous profilin. The proline-rich sequences of ActA are unlikely to be the target of profilin. All data support the view that actin assembly at the rear of Listeria results from a local shift in steady state due to a factor, keeping filaments uncapped, bound to the surface of the bacterium, while barbed ends are capped in the bulk cytoplasm. Movement is controlled by the energetic difference (i.e., the difference in critical concentration) between the two ends of the filaments, hence a constant ATP supply and the presence of barbed end capped F-actin in the medium are required to buffer free G-actin at a high concentration. The role of membrane components is demonstrated by the facts that: (a) Listeria movement can be reconstituted in the resuspended pellets of high speed-centrifuged extracts that are enriched in membranes; (b) Actin-based motility of endogenous vesicles, exhibiting the same rocketing movement as Listeria, can be observed in the extracts.

Actins↗
PubMed1985

Mutagenicity studies in a tyre plant: in vitro activity of workers' urinary concentrates and raw materials.

The possible contribution to urinary mutagenicity of occupational exposures in the rubber industry was studied by assaying the urine concentrates of 72 workmen (44 smokers) employed in a tyre plant. Twenty three clerks (16 smokers) engaged in the administrative department of the same factory served as presumptive unexposed controls. XAD-2 resin concentrates of urine samples were assayed in the plate incorporation test and in the microtitre fluctuation assay with Salmonella typhimurium strains TA1535, TA98, and TA100. Furthermore, the in vitro mutagenicity of the major raw materials in use at the plant was determined in the plate incorporation assay with S typhimurium strains TA1535, TA1537, TA98, and TA100. The results obtained from the urinary mutagenicity study show that smoking habits, but not occupation, were statistically significantly related to the appearance of a urinary mutagenicity that was detectable with strain TA98. A possible synergistic effect of occupation with smoking was observed among tyre builders who were also smokers. The study of the raw materials showed that three technical grade materials were weakly active as mutagens in strain TA98 in the absence (poly-p-dinitrosobenzene) or in the presence of metabolic activation (mixed diaryl-p-phenylendiamines and tetramethyltiuram disulphide). The latter chemical was also weakly active in strain TA100.

Chemical Industry↗
PubMed1984

[Echographic identification of an isolated thyroid nodule].

103 patient suffering from thyroid solitary nodule have been examined with gray-scale ultrasonography. 79 patients have been histologically confirmed. Research has been done with multi-transducer computerized water-bath equipment ( OCTOSON ). The results are discussed and a classification of the thyroid solitary nodule in four groups is proposed, according to the echographic patterns.

Adenoma↗
PubMed1984

Biological monitoring of workers in the rubber industry. I. Chromosomal aberrations and sister-chromatid exchanges in lymphocytes of vulcanizers.

To evaluate the possible genetic consequences of the industrial exposure among the vulcanizers of a rubber plant we measured the in vivo levels of chromosomal aberrations and sister-chromatid exchanges in peripheral lymphocytes of 34 vulcanizers and in an adequate control population. The observed chromosomal aberration frequencies were 1.9 +/- 1.4 aberrations/100 cells in the exposed group and 2.1 +/- 1.5 aberrations/100 cells in the controls. No difference was found between the two groups for the mean value of sister-chromatid exchanges (5.2 +/- 1.3 in the exposed, 5.2 +/- 0.7 in the control group). Cigarette-smoking was clearly associated with increased sister-chromatid exchange frequencies both in the exposed and in the control groups, while chromosomal aberration frequencies were not correlated with smoking habits.

Chromosome Aberrations↗