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Biomedical subjects

L Conti

Publications and source records attributed to L Conti.

At least 37 records · Page 2Linked to original sources
PubMed2000

Impairment of human immunodeficiency virus type 1 (HIV-1) entry into Jurkat T cells by constitutive expression of the HIV-1 vpr protein: role of CD4 down-modulation.

Jurkat T-cell clones, stably expressing the human immunodeficiency virus type 1 (HIV-1) Vpr protein, exhibited an impaired susceptibility to HIV-1 infection. A marked down-modulation of surface CD4 receptors was detected in Vpr-expressing clones with respect to control cells. Likewise, a reduced CD4 expression was also observed in parental Jurkat cells infected with wild-type but not with Vpr-mutant HIV-1. Notably, Vpr-expressing clones were fully susceptible to infection with a vesicular stomatitis virus G protein-pseudotyped HIV-1 virus, indicating that a block at the level of viral entry was responsible for the inhibition of viral replication. The effect exerted by Vpr on HIV replication and CD4 expression suggests that this protein can regulate both the establishment of a productive HIV-1 infection and CD4-mediated T-cell functions.

CD4 Antigens↗
PubMed2000

Regulation of chemokine/cytokine network during in vitro differentiation and HIV-1 infection of human monocytes: possible importance in the pathogenesis of AIDS.

The monocyte/macrophage lineage represents heterogeneous cell populations characterized by major differences in the phenotype and functional activities. These cells are a major source of soluble factors, such as cytokines and chemokines, which can both affect HIV replication and AIDS pathogenesis. Although monocytes/macrophages are unanimously considered important targets of HIV-1 infection, the HIV-induced alterations in their physiological functions at different stages of differentiation are still matter of debate. In this article, we review our data on the regulation of chemokine/cytokine network with regard to macrophage differentiation and HIV-1 infection, in comparison with studies from other groups. The ensemble of the results emphasizes that: 1) macrophages markedly differ with respect to monocytes for a variety of responses potentially important in the pathogenesis of HIV infection; and 2) the experimental conditions can influence the HIVmonocyte/macrophage interactions, reflecting the possible in vivo existence of a spectrum of responses among macrophage populations.

Cell Differentiation↗
PubMed2000

Cranio-orbital missile wound and bullet migration. Case report.

An unusual case of craniocerebral missile injury, with orbital roof perforation and spontaneous bullet migration into the maxillary sinus, is reported. Emergency treatment consisted in wide craniectomy around the bullet entry point, blood and foreign bodies debridement. Subsequent procedures were necessary for abscess evacuation, transmaxillary bullet removal and later cranial vault reconstruction. Challenging aspects were the treatment of the infectious complications, following cerebrospinal fluid fistula through the wound, and the onset of post-traumatic epilepsy, scarcely responsive to common antiepileptic drugs. The treatment of the abscess by combined systemic and intracavitary antibiotic therapy and of the chronic seizures by progressive adjustment with new protocols of antiepileptic drugs under EEG and brain mapping revealed successful.

Adult↗
PubMed2000

[Gastrointestinal stromal tumors (GIST). Our experience].

Nine cases of gastrointestinal stromal tumors (GISTs) observed in the period between 1993 and 1999 and treated with radical surgery are presented. Patients were studied with instrumental examinations (ultrasonography, TC, EGDS, RSCS, endoscopic ultra-sound) which permitted to make a temporary diagnosis of "suspect gastric or bowel neoplasm". Only after surgical resection of the neoplasm it was possible to make a definitive diagnosis, based on histologic examination of the operating piece. According to personal experience and literature data, we could affirm that GISTs' clinical manifestations are extremely heterogeneous and so these tumors are often diagnosed casually. Prognosis isn't correlated as much to neoplasm histologic and cytologic characteristics, as to next organs infiltration, which represents a sign of particular aggressiveness of lesions.

Adult↗
PubMed1999

Signalling through the JAK-STAT pathway in the developing brain.

The JAK -STAT (Janus kinase-signal transducer and activator of transcription) signalling pathway that is stimulated by cytokines has been much investigated in haematopoietic cells, but recent data indicate that this pathway is also present and active during neuronal and glial differentiation. Furthermore, it is now clear that growth factors other than the classical cytokines can act through this pathway and that physiological inhibitors of this signalling cascade exist. Thus, the JAKs, the STATs and their specific inhibitors could be molecules with important roles in the CNS.

Aging↗
PubMed1999

Evaluation of 10 aliphatic halogenated hydrocarbons in the mouse bone marrow micronucleus test.

Ten halogenated aliphatic hydrocarbons (carbon tetrachloride, 1-chlorohexane, 2,3-dichlorobutane, 1,2-dichloroethane, 1,2-dichloroethylene, 1,3-dichloropropane, hexachloroethane, 1,1,2-trichloroethane, 1,2,3-trichloropropane and 1,1,3-trichloropropene), previously assayed in genetic assays in fungi, were evaluated in the mouse bone marrow micronucleus test in order to assess their genotoxicity in vivo. All chemicals were administered once i.p. at 40 and 70-80% of their respective LD50 to male and female CD-1 mice, 24 and 48 h before killing. All treatments produced evident clinical symptoms, but no marked depression of bone marrow proliferation. No statistically significant increases in the incidence of micronucleated polychromatic erythrocytes over the control values were observed at any sampling time with any of the 10 halogenated hydrocarbons assayed. The comparison of the results obtained in this study with the findings provided by in vitro micronucleus assays on the same chemicals, reported by other authors, indicate that mouse bone marrow is weakly sensitive to the genotoxic effects induced by halogenated hydrocarbons in other test systems. This suggests that the role of such an assay in carcinogen screening may be questionable for this chemical class. An examination of mouse bone marrow micronucleus test results with the halogenated aliphatic hydrocarbons classified as carcinogens by IARC supports this conclusion.

Animals↗
PubMed1999

Long-term follow-up of autoimmune thrombocytopenic purpura (ATP) patients submitted to splenectomy.

We studied the general outcome in 94 adult patients with autoimmune thrombocytopenic purpura (ATP) submitted to splenectomy. Of 84/94 patients who presented a complete or partial response 30 d after splenectomy, 16 (19%) showed one or more relapses. The clinical situation of the 81 patients still under observation is as follows: 13 unresponsive, 60 completely or partially responsive, without relapses during the follow-up, 8 completely or partially responsive after one or more relapses. No correlation was found between the favourable splenectomy outcome and age at splenectomy, the diagnosis-splenectomy interval and initial response to corticosteroids. The probability of disease-free survival is 83%, projected at 10 yr, while the overall survival is 93%, projected at 10 yr. PAIgG levels of the normal subjects and of responding patients were found to be similar, while in the groups of non-responding/relapsing patients, significantly higher values of PAIgG were detected, as compared to the control group.

Adolescent↗
PubMed1999

Expression of the JAK and STAT superfamilies in human meningiomas.

OBJECT: The goal of this study was to investigate whether the janus kinase/signal transducer and activator of transcription (JAK/STAT) signal transduction pathway is present and active in meningiomas. The results of these investigations are important for all meningioma therapies that, similar to interferon-alpha-2B (IFNalpha-2B), depend on activation of this pathway for their effect. The authors were interested in evaluating the importance, if any, of the JAK/STAT pathway in the biology and therapy for these tumors. METHODS: Total proteins were extracted from 17 meningioma samples and the levels of JAKs and STATs were determined by using Western blot analysis. Levels of these proteins in meningiomas were compared with those found in normal dura. The JAKs and STATs (with the exception of Jak3 and Tyk2) were present both in the dura and in the meningiomas studied. In tumors JAK and STAT levels were always significantly higher than those found in normal dura. Differences in relative levels were found when meningiomas were subdivided according to the current neuropathological criteria and the highest levels were found in transitional meningiomas. The authors also investigated, using tyrosine-phosphorylated Statl and Stat3 antibodies, whether STATs were activated in meningiomas and normal dura in vivo. Their results indicate that both Statl and Stat3 are phosphorylated in vivo in meningiomas and in the dura. Furthermore, in vitro experiments in which two independent short-term cultures obtained from freshly dissected meningioma samples were used indicated that Statl and Stat3 are phosphorylated in response to treatment with IFNalpha-2B. Exposure of meningioma cells to IFNalpha-2B leads to nuclear translocation of tyrosine-phosphorylated Statl and Stat3, as demonstrated by immunocytochemical analysis. CONCLUSIONS: The results of this study indicate that the JAK and STAT families of proteins are important effectors in brain tumors and support the idea that the effects of IFNalpha in vivo are direct and not mediated by the immune system. This suggests a role for modulation of STAT transcription factors in inhibiting meningioma cell proliferation.

Acute-Phase Proteins↗
PubMed1998

Members of the JAK/STAT proteins are expressed and regulated during development in the mammalian forebrain.

The presence and activation of members of the Janus Kinases/Signal Transducers and Activator of Transcription proteins in response to specific cytokines is currently the focus of intense investigation in the hematopoietic system. Although some evidence suggests that cytokines might play an important role in brain development and brain pathologies, very limited information is available on the presence of the JAK/STAT proteins in the Central Nervous System. Here we provide Western blot and immunohistochemistry data on the presence of Jak2 in vivo in the immature brain, its expression being greater in early stages of the embryonic life and gradually diminishing towards adulthood. Conversely, Jak1 was found expressed at a lower level compared to Jak2 and not modulated during brain maturation. Western blot data also show that specific members of the STAT family, the cytoplasmic substrates of the Janus Kinases, are present in vivo and that the extent of their expression is modulated differently at various stages. In particular, Stat6 protein levels were markedly attenuated at advanced stages of differentiation, as well as in the adult brain, with respect to early embryonic life. On the contrary, Stat3 levels did not vary. Analysis of Statl and Stat5 proteins showed a more complex expression pattern. These data indicate that members of the JAK/STAT proteins are present and modulated in vivo in the embryonic and postnatal brain, therefore supporting their role in the modulation of gene expression during the different stages of brain maturation.

Animals↗
PubMed1998

Generation and characterization of embryonic striatal conditionally immortalized ST14A cells.

Neural progenitor cells have been isolated from the embryonic central nervous system (CNS) of several mammalian species. These exhibit properties of immature cells, including expression of the intermediate filament protein Nestin, the ability to self renew, and to give rise to terminally differentiated cell types. In this study we describe some of the properties of ST14A cells, which were established via retroviral transduction of the temperature-sensitive mutant of the SV40 Large T Antigen into primary cells derived from the embryonic day 14 (E14) rat Striatum primordia. At 33 degrees C, ST14A cells proliferate and express Nestin, whereas at the nonpermissive temperature, cell growth becomes restricted in coincidence with the disappearance of the immortalizing oncoprotein. We also describe the ability of ST14A cells to differentiate and express MAP2. Furthermore, we analyzed the expression of specific growth factors and growth factor receptors in the ST14A cells, and found that nerve growth factor (NGF) and Trk receptors are most commonly expressed.

Animals↗
PubMed1998

Inhibition of human immunodeficiency virus type 1 replication by nuclear chimeric anti-HIV ribozymes in a human T lymphoblastoid cell line.

Human immunodeficiency virus (HIV) infection represents one of the most challenging systems for gene therapy. Thanks to the extended knowledge of the molecular biology of the HIV life cycle, many different strategies have been developed including transdominant modifications of HIV proteins, RNA decoys, antisense RNA, ribozymes, and intracellular antibody fragments. In this paper, we have tested in a human T lymphoblastoid cell line the antiviral activity of ribozymes specifically designed to co-localize inside the nucleus with the Rev pre-mRNA before it is spliced and transported to the cytoplasm. This result was obtained by inserting the ribozyme in the spliceosomal U1 small nuclear RNA (snRNA) and in a derivative that has perfect complementarity with the 5' splice site of the Rev pre-mRNA. These ribozymes were tested in human T cell clones and were shown to be very efficient in inhibiting viral replication. Not only were the p24 levels in the culture medium drastically reduced but so were the intracellular HIV transcripts. Control disabled ribozymes enabled us to show the specificity of the ribozyme activity. Therefore, these constructs have potential utility for gene therapy of HIV-1 infection.

Anti-HIV Agents↗
PubMed1998

The HIV-1 vpr protein acts as a negative regulator of apoptosis in a human lymphoblastoid T cell line: possible implications for the pathogenesis of AIDS.

Although apoptosis is considered one of the major mechanisms of CD4(+) T cell depletion in HIV-infected patients, the virus-infected cells somehow appear to be protected from apoptosis, which generally occurs in bystander cells. Vpr is an auxiliary HIV-1 protein, which, unlike the other regulatory gene products, is present at high copy number in virus particles. We established stable transfectants of CD4+ T Jurkat cells constitutively expressing low levels of vpr. These clones exhibited cell cycle characteristics similar to those of control-transfected cells. Treatment of control clones with apoptotic stimuli (i.e., cycloheximide/tumor necrosis factor alpha (TNF-alpha), anti-Fas antibody, or serum starvation) resulted in a massive cell death by apoptosis. In contrast, all the vpr-expressing clones showed an impressive protection from apoptosis independently of the inducer. Notably, vpr antisense phosphorothioate oligodeoxynucleotides render vpr-expressing cells as susceptible to apoptosis induced by cycloheximide and TNF-alpha as the control clones. Moreover, the constitutive expression of HIV-1 vpr resulted in the upregulation of bcl-2, an oncogene endowed with antiapoptotic activities, and in the downmodulation of bax, a proapoptotic factor of the bcl-2 family. Altogether, these results suggest that low levels of the endogenous vpr protein can interfere with the physiological turnover of T lymphocytes at early stages of virus infection, thus facilitating HIV persistence and, subsequently, viral spread. This might explain why apoptosis mostly occurs in bystander uninfected cells in AIDS patients.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Vulvar squamous carcinoma: prognostic role of DNA content.

DNA nuclear content was evaluated on 46 paraffin-embedded blocks of vulvar cancer by means of flow cytometry. Fifteen of 44 evaluable samples (34%) were found to have an aneuploid DNA pattern. Aneuplody showed a statistically significant relationship with tumor grading (P = 0.0004) and defined a subset of patients who have pathological characteristics of high risk, such as advanced stage of disease, deepest stromal invasion, or positive inguinal nodes. However, when a multivariate regression model was used, ploidy status did not have any prognostic role, while FIGO staging system was confirmed to be the strongest independent prognostic factor (P = 0.009). The integration of a panel of cell kinetic parameters with traditional features is worth investigating on a larger population.

Adult↗
PubMed1998

Methodological issues in biomonitoring of low level exposure to benzene.

Data from a pilot study on unmetabolized benzene and trans,trans muconic acid (t,t-MA) excretion in filling station attendants and unexposed controls were used to afford methodological issues in the biomonitoring of low benzene exposures (around 0.1 ppm). Urinary concentrations of benzene and t,t-MA were measured by dynamic head-space capillary GC/FID and HPLC, respectively. The accuracy of the HPLC determination of t,t-MA was assessed in terms of inter- and intra-method reliability. The adequacy of urinary t,t-MA and benzene as biological markers of low benzene exposure was evaluated by analysing the relationship between personal exposure to benzene and biomarker excretion. Filling station attendants excreted significantly higher amounts of benzene, but not of t,t-MA, than controls. Adjusting for occupational benzene exposure, smokers excreted significantly higher amounts of t,t-MA, but not of unmetabolized benzene, than nonsmokers. A comparative analysis of the present and previously published biomonitoring surveys showed a good inter-study agreement regarding the amount of t,t-MA and unmetabolized benzene excreted (about 0.1-0.2 mg/l and 1-2 micrograms/l, respectively) per unit of exposure (0.1 ppm). For each biomarker, based on the distribution of parameters observed in the pilot study, we calculated the minimum sample size required to estimate the population mean with given confidence and precision.

Adult↗
PubMed1998

[Atropine poisoning. Importance of the clinical diagnosis].

A case of suspected high dose atropine poisoning is described. In a veterinarian good healthy young man the appearance of light coma with psychomotor agitation and the contemporary presence of evident symptoms of muscarinic peripheral block, suggesting an anticholinergic syndrome, an atropine-like intoxication in absence of toxicological analysis. The safely clinical course of the poisoning during observation in intensive care unit permitted the discharge of the patient without sequelae and without treatment with physostigmine as antidote.

Adult↗
PubMed1997

Expression and activation of SH2/PTB-containing ShcA adaptor protein reflects the pattern of neurogenesis in the mammalian brain.

The adult mammalian brain comprises many functionally distinct neuronal types, which are generated during development as a result of a coordinated signaling cascade that drives neuroblasts from proliferation into differentiation. We investigated whether and how ShcA adaptor proteins, which are known to function as initiators of the Ras signaling cascade in various nonneuronal systems where they have been considered to be expressed ubiquitously, are involved in the proliferative and differentiative phases of the developing brain. We found that in the forebrain expression and activation of ShcA proteins were strictly regulated during embryonic development, both temporally and spatially. The mRNAs encoded by the ShcA gene were expressed exclusively within an area to which active proliferation of immature neuroblasts was confined, the ventricular zone. In postnatal and adult brain, ShcA mRNAs and proteins were present only faintly. In the adult olfactory epithelium, in which neuronal cell renewal occurs throughout life, ShcA remained strongly expressed. These phenomena were peculiar to ShcA, since Grb2 adaptor protein remained expressed at constant level throughout development. The embryonically expressed ShcA proteins were functionally active, since p52(ShcA) became phosphorylated on tyrosine and associated with Grb2 following intraventricular injection of epidermal growth factor in the embryonic brain. Our data indicate that, through an orderly pattern of expression, ShcA gene products may play a role in the control of the switch between proliferation and differentiation of brain neuroblasts.

Adaptor Proteins, Signal Transducing↗
PubMed1997

Induction of cytokines by HIV-1 and its gp120 protein in human peripheral blood monocyte/macrophages and modulation of cytokine response during differentiation.

We previously reported that in vitro culture of human peripheral blood monocytes resulted in a time-dependent differentiation into macrophages and in an enhanced capacity for producing certain cytokines [i.e., tumor necrosis factor alpha, interleukin-6 (IL-6), and interferon-beta (IFN-beta)] in response to bacterial lipopolysaccharide (LPS). HIV-1 infection or gp120 treatment of monocyte/macrophages resulted in the induction of low levels of IFN-beta, which were very effective in restricting viral replication in 7-day cultured macrophages but not in freshly isolated cells. This enhanced response of macrophages was due to a higher sensitivity of these cells to the antiviral effect of IFN-beta. Consistent with this finding, 7-day cultured macrophages exhibited higher levels of type I IFN receptors than 1-day cultured monocytes. Treatment of monocyte/macrophages with gp120 also caused a marked increase in IL-10 secretion, regardless of the differentiation state. No IL-12 secretion was detected in monocyte/macrophage cultures treated with gp120 alone. However, consistent IL-12 secretion was found in 7-day cultured macrophages primed with IFN-beta and subsequently stimulated with gp120. Macrophages responded more efficiently than monocytes to the priming effect of IFN-beta for IL-12 production. This was consistent with a stronger antiviral response against vesicular stomatitis virus by these cells as well as with a higher expression of IFN-beta receptors. The finding that the acquisition of the macrophage phenotype is associated with an increased capacity to respond to environmental signals (such as type I and type II IFNs) underlines the importance of the differentiation process for the selection of a certain repertoire of responses that may allow these cells to have important functions in vivo.

Cell Differentiation↗