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Biomedical subjects

C Pignata

Publications and source records attributed to C Pignata.

At least 37 records · Page 2Linked to original sources
PubMed1999

Formation of N-(2-hydroxyethyl)valine due to exposure to ethylene oxide via tobacco smoke: A risk factor for onset of cancer.

Human exposure to ethylene oxide (EtO) occurs mainly through inhalation of occupational polluted air and tobacco smoke. EtO is able to react with DNA and proteins producing some molecular adducts. One of these, resulting from reaction between EtO and valine in hemoglobin, is N-(2-hydroxyethyl) valine (HOEtVal). This adduct represents a biological effective dose marker, the level of which correlates linearly with the alkylating activity occurring in DNA. The aim of the present study was to measure HOEtVal in 146 urbanized adult and healthy subjects, nonoccupationally exposed to EtO, and to correlate it with smoke habits. HOEtVal showed a direct positive relationship to tobacco smoke exposure quantified by questionnaire, urinary cotinine (r=0.64509), and the number of cigarettes (r=0. 6308) actively or passively smoked. Results relative to HOEtVal and urinary cotinine in adults distinguish well between active and passive smokers but do not allow distinguishment between passive smokers and nonsmokers. Nevertheless, several authors demonstrated a very good capacity of cotinine to discriminate inside groups of adolescents passive smokers. Therefore, the future objective of the present study is a closer inspection of the two biomarkers with respect to passive exposure to tobacco smoke considering a large group of adolescents. Finally, the correlation between urinary cotinine and HOEtVal increases knowledge about early steps of the carcinogenic process due to active exposure to tobacco smoke.

Adolescent↗
PubMed1998

Occupancy of dipeptidyl peptidase IV activates an associated tyrosine kinase and triggers an apoptotic signal in human hepatocarcinoma cells.

Dipeptidyl peptidase IV (CD26/DPP-IV) is an ectoenzyme expressed on different cell types. Signaling properties and functional consequences of the CD26 triggering have been elucidated mostly on T cells, where the molecule delivers a costimulatory signal that potentiates T-cell activation through the T-cell receptor. We conducted studies in the human hepatocarcinoma-derived PLC/PRF/5 cell line to examine the signal transduction through CD26 and its functional properties in the absence of other T-cell-specific membrane molecules. Engagement of CD26 in PLC/PRF/5 cells through a specific antibody induces tyrosine phosphorylation of several proteins with maximal intensity 15 minutes after the stimulation. This effect was under the negative regulatory control of CD45 tyrosine phosphatase, in that the addition of orthovanadate clearly enhanced the phosphorylation events. Using in vitro kinase assays with CD26 immunoprecipitates, we observed that a protein or proteins with kinase activity are coprecipitated with the CD26 molecule. In addition, unlike Jurkat T cells, in which CD26 expression exerts a protective effect against apoptosis, in PLC/PRF/5 cells CD26 occupancy delivers a potent apoptotic signal. This effect was also observed in HepG2 cells, thus indicating that it represents a more general phenomenon occurring in different liver neoplastic cell lines.

Apoptosis↗
PubMed1998

Chronic unexplained liver disease in children with primary immunodeficiency syndromes.

Liver disease may be found in patients with primary immunodeficiency syndromes because of the high risk of infection with hepatotropic viruses related to the treatment with blood derivatives. The prevalence of liver disease in these patients and its etiology, however, is still not completely understood. We have evaluated the prevalence and the etiology of liver disease in children with different forms of primary immunodeficiencies. Thirty patients included in the study underwent molecular studies to detect common hepatotropic viruses, including hepatitis C and G viruses. Liver involvement was found in 11 of 30 (36.6%) patients. All patients with liver disease had deficiencies of specific immunity, with a prevalence in this subgroup of 47.8%. Liver disease was more severe in patients with T and B cell combined immune disorders than in those with a selective T cell immunodeficiency. Moreover, the severity of the disease correlated with an overall more rapid fatal outcome. A viral etiology was found in only six of these patients, whereas in the remaining five patients, no cause of liver injury was identified. In the virally infected patients, hepatitis C virus was the most common viral agent. In patients with immunodeficiencies, there is a high prevalence of liver disease not fully explained on the basis of the common viral infections.

Adolescent↗
PubMed1998

Apoptosis as a mechanism of peripheral blood mononuclear cell death after measles and varicella-zoster virus infections in children.

Viral infections may induce an acquired form of immunodeficiency, generally lasting a few weeks. In the more severe form, such as HIV infection, the immunodeficiency is permanent. Programmed death of T cells represents one of the mechanisms by which HIV determines the T cell functional impairment, finally resulting in the destruction of T cells. In this study, we evaluated whether an altered regulation of apoptosis was also implicated in the anergy associated with the common measles or varicella-zoster virus (VZV) infections in infancy. A spontaneous apoptosis of peripheral blood mononuclear cells was observed in children who had suffered from these infections as long as 6 mo after the acute disease. Apoptosis was demonstrated through analysis of cellular DNA content, morphologic evidence of cell nuclei shrinkage, and by analysis of DNA degradation. Stimulation of T cells through anti-CD4 MAb increased the number of apoptotic cells with a maximal effect 72 h after the stimulation. Our results suggest that apoptosis may account for the anergy that follows acute viral infections in infancy.

Apoptosis↗
PubMed1998

T cell activation deficiency associated with an aberrant pattern of protein tyrosine phosphorylation after CD3 perturbation in Down's syndrome.

Children affected by Down's syndrome (DS) have an increased susceptibility to viral or bacterial infections and leukemia, associated with several abnormalities of the immune system. We investigated whether the T cell defect was qualitative in nature and associated with abnormalities of the early events occurring during cell activation. The proliferative response of lymphocytes from DS individuals after CD3 cross-linking was clearly depressed, as already reported. In contrast, phorbol ester and ionomycin were able to induce cell cycle progression in DS, suggesting a defect in the early stages of the signal transduction through a T cell receptor/CD3 (TCR/CD3) complex upstream of protein kinase C activation. The functional impairment in DS was not related either to a decrease of circulating mature-type CD3+ cells, which express high levels of surface of CD3 molecules, or to a decrease of the CD4+ subpopulation. The analysis of phosphotyrosine-containing proteins after the cross-linking of CD3 molecules in DS lymphocytes revealed a partial signaling, characterized by increased phosphorylation of proteins of 42-44 kD, comparable to that observed in control subjects, but not of proteins of 70 and 21 kD. Moreover, although the "anti-anergic" gamma element of IL-2, IL-4, IL-7, and IL-15 receptors was normally tyrosine-phosphorylated during cell activation, the CD3 zeta-associated protein kinase (ZAP-70) was not. Our results indicate that in DS there is a T cell activation defect, characterized by partial signal transduction through a TCR/CD3 complex, and associated with a selective failure of ZAP-70 tyrosine phosphorylation.

Adolescent↗
PubMed1997

Increased CD5+CD19+ B lymphocytes at the onset of type 1 diabetes in children.

The aim of this study was to determine whether the proportion of circulating B cells expressing the differentiative antigen CD5 was increased in children affected by type 1 diabetes, and whether the number of these cells was correlated with the presence of anti-islet cell autoantibodies. Sixteen children affected by insulin-dependent diabetes mellitus (type 1) were investigated for the presence of B lymphocytes bearing the CD5 surface molecule, T-cell-specific activation markers, organ- and nonorgan-specific autoantibodies. The number of CD5+CD19+ cells was higher in type 1 children with a very recent onset of the disease, as compared with patients on insulin therapy for more than 30 days and controls (P < 0.05). No correlation was found between the number of CD5+CD19+ cells and the presence of either organ- or nonorgan-specific autoantibodies. Our results indicate that CD5+CD19+ cells are involved in the pathogenesis of type 1 diabetes in children. A potential immunoregulatory role of this B cell population is discussed.

Age of Onset↗
PubMed1997

Combined immunodeficiency phenotype associated with inappropriate spontaneous and activation-induced apoptosis.

Programmed death of T cells has been proposed as one of the mechanisms by which HIV induces a decline in the number and functions of T cells in advanced AIDS. In this study we report on a patient affected by a congenital form of combined immunodeficiency presenting as a profound T cell activation deficiency. Subsequently, a gradual loss of T cells occurred, eventually resulting in a classical form of severe combined immunodeficiency (SCID). In this patient a sizeable fraction of apoptotic cells was documented in the first phase of the disease by either propidium iodide staining or DNA fragmentation analysis. The presence of anergic T cells of maternal origin and engrafted in the child was excluded by analysis of DNA polymorphic regions. At 4 years of age the patient died of disseminated interstitial pneumopathy, while still awaiting an HLA-matched bone marrow transplantation. On the occasion of a new pregnancy in the mother, the prenatal immunological evaluation of the female fetus revealed a T B+ SCID phenotype. This is the first observation of a primary immunodeficiency associated with inappropriate apoptosis.

Apoptosis↗
PubMed1997

Defective interleukin-2 production in children with chronic hepatitis B: role of adherent cells.

BACKGROUND: Chronic hepatitis B (CHB) virus infection is associated with functional abnormalities of cell-mediated immunity, defective interferons alpha and gamma synthesis, and interleukin-2 receptor expression. In this study, interleukin-2 (IL-2) production and the role of adherent cells was evaluated in 25 children chronically infected with hepatitis B virus. METHODS: IL-2 activity was measured by bioassay in supernatants of phytohemoagglutinin-stimulated peripheral blood mononuclear cells. In a few patients, IL-2 concentration was also immunochemically determined. Coculture experiments using a mixture of adherent cells and lymphocytes from healthy children and patients with CHB were also performed. RESULTS: Children with CHB showed lower IL-2 production than healthy controls. In patients, IL-2 activity was 34.7 +/- 22.5 U/ml as compared to 152.6 +/- 78.5 U/ml of controls. Immunochemical quantitation of IL-2 confirmed a lower IL-2 production in patients. No correlation was found between the functional T-cell defect and the severity of liver damage, degree of viral replication, and duration of the disease. In co-culture experiments, adherent cells from HBsAg-positive patients inhibited IL-2 production following mitogen stimulation of control non-adherent cells by 67%. The inhibitory effect, mediated by patients adherent cells, was abolished by blocking with indomethacin prostaglandins, that are potent local immunomodulators released by adherent cells. CONCLUSIONS: Our results further support the observation that in children with CHB virus infection adherent cells play an important role in the inappropriate regulation of immune response, an effect being likely mediated by prostaglandins.

Adolescent↗
PubMed1996

Congenital Alopecia and nail dystrophy associated with severe functional T-cell immunodeficiency in two sibs.

We report on two sisters affected by congenital alopecia, nail dystrophy, and a severe T-cell immunodeficiency, presumably inherited as an autosomal-recessive disorder. The T-cell defect was characterized by severe functional impairment, as shown by the lack of proliferative response and upregulation of activation markers following mitogen stimulation. The functional abnormality occurred in spite of the presence of phenotypically mature of the defect. This is the first observation reported on an ectodermal disorder, characterized by alopecia and nail dystrophy, observed at birth, in association with a primary immunodeficiency. The hypothesis that these two events may be casually related is discussed.

Alopecia↗
PubMed1996

Defective activation of mitogen-activated protein kinase after allogeneic bone marrow transplantation.

Allogeneic bone marrow transplant (BMT) recipients have increased susceptibility to infections for prolonged periods after phenotypic reconstitution of donor cells. This immunodeficiency status is characterized by multiple T-cell functional abnormalities. This study was designed to investigate several signaling pathways involved in T-cell activation during this period of immune deficiency. In initial experiments using equal numbers of CD3+ cells or highly purified T-cell subpopulations obtained from normal controls and BMT recipients, we confirmed that abnormal T-cell proliferation after CD3 cross-linking, phytohemagglutinin stimulation, or phorbol myristate acetate (PMA) stimulation of peripheral blood mononuclear cells from BMT recipients was due to a qualitative T-cell deficiency rather than to low numbers of circulating T cells. We next investigated the ability of the T-cell receptor/CD3 complex to transduce signals via receptor-associated protein tyrosine kinases. In all BMT recipients, CD3 cross-linking induced protein tyrosine phosphorylation of several proteins in a similar fashion to that seen in controls, including phosphorylation of a 21-kD protein that represents the zeta subunit of the receptor itself. Further investigation showed that CD3 cross-linking and PMA stimulation did not increase 42-44-kD mitogen-activated protein kinase (MAPK) activity. The failure of MAPK activation in BMT recipients occurred despite tyrosine phosphorylation of the 42-44-kD proteins, which, in normal controls, parallels enzyme activation. Our results indicate that T-cell immunodeficiency in BMT recipients is associated with a selective failure of MAPK activation, possibly related to abnormal posttranslational positive regulation of this enzyme.

Adult↗
PubMed1996

Progressive deficiencies in blood T cells associated with a 10p12-13 interstitial deletion.

We report on a 8-year-old patient affected by a selective T-cell defect associated with mental retardation and dysmorphic signs. At birth thymic aplasia and hypoparathyroidism were noted, suggesting a DiGeorge-like anomaly. The immunological evaluation during the 8 years follow-up revealed a progressive decrease of CD3+CD4+ lymphocytes, which paralleled deficiencies of blood T cells. Chromosome analysis using GTL banding revealed an interstitial deletion of the short arm of chromosome 10. We next investigated whether the expression of IL-2R alpha chain and Nil-2-a genes, which are located on the short arm of chromosome 10, was affected by the deletion. Transcription of these two genes was normal, thus suggesting that the two regions were preserved. In situ hybridization studies with the painting libraries #G3A7 and #G9 confirmed that the two regions were preserved and allowed us to define the breakpoint as 10p12-10p13. Due to the similarities between DiGeorge and 10p syndromes, we suggest that the 10p13-10p12 region contains a gene(s) potentially related to gene products of the 22q11 region, frequently altered in patients with DiGeorge.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1996

Severe, protracted intestinal cryptosporidiosis associated with interferon gamma deficiency: pediatric case report.

We describe a human immunodeficiency virus-negative infant with chronic intractable diarrhea due to Cryptosporidium parvum; he had a history of significant weight loss since the second week of life. A preliminary study of his immune function was negative for primary immunodeficiency. To further study his immune function, proliferation of peripheral blood mononuclear cells (PBMCs) was elicited by crude antigenic extract from C. parvum oocysts (CCE). Supernatants of CCE-stimulated PBMCs contained interleukin 10 but not interferon gamma (IFN-gamma), while PBMCs from a control (a 2-year-old immunocompetent infant who had recovered from cryptosporidiosis) showed a strong response to IFN-gamma when stimulated with CCE. These results stress the role of IFN-gamma in recovery from cryptosporidiosis.

Animals↗
PubMed1995

Phosphorylation of src family lck tyrosine kinase following interleukin-12 activation of human natural killer cells.

Interleukin-12 (IL-12) is a heterodimeric cytokine that augments the cytolytic activity of human NK cells and T cells but has little mitogenic activity on resting lymphocytes. The intracellular signaling pathways involved in NK cell activation by IL-12 have not been fully characterized. In the present studies we found that IL-12 induces tyrosine phosphorylation of a 56-kDa protein, identified in Western blot experiments as p56lck, in resting NK cells. IL-12 was active in the range of 0.1 to 1000 U/ml, with maximal activity between 10 and 100 U/ml (30 and 300 pM). The maximal effect was noted 5 min after stimulation and was almost completely inhibited by genistein. IL-12 induced similar effects in resting and IL-2 activated NK cells. Following IL-12 stimulation of resting NK cells, immunoprecipitated lck kinase exhibited increased in vitro autophosphorylation activity 5 and 10 min after activation. Several additional substrates were phosphorylated in vitro following IL-12 stimulation, including proteins of 70 and 110 kDa. These studies indicate that lck tyrosine kinase is involved in the IL-12 signaling pathway in human NK cells. As the primary functional effect of IL-12 on resting NK cells is the enhancement of cytolytic activity and secretory function rather than cell proliferation, these findings suggest that lck tyrosine kinase is involved in these signaling pathways in human NK cells.

Animals↗
PubMed1995

Updating about reductions of air and blood lead concentrations in Turin, Italy, following reductions in the lead content of gasoline.

Considering its well-know toxicity and the chronic human exposure to lead, international law-makers enforced some directives or laws calling for the reduction of lead content of gasoline. All of these legislative acts aimed to reduce health risks for the general population. The aim of this study was to consider the effectiveness of these laws on air lead levels and consequently on blood lead levels in a randomly selected urban Italian population. In particular, these markers were analyzed over the course of several years, corresponding to the periods just before and after enforcements of the reductions of lead in petrol. Data presented point out some considerations: (1) enforcement of legislative measures concerning the reduction of lead in petrol has reduced atmospheric levels of lead. This result demonstrates a major environmental success in primary prevention efforts. (2) This success is clear especially considering that the actual Pb-B levels can be extended to the urbanized populations. Pb-B levels were consistently higher for drinkers, for older adults, and for males. The mean of Pb-B level for the present urbanized population is higher than the U.S. overall population (6.4 vs 3 microgram/dl). This difference can be also explained considering the different historical period of enforcement of the restriction laws.

Adult↗
PubMed1995

DNA typing of DQ and DR alleles in IgA-deficient subjects.

IgA deficiency (IgA-D) represents the most common immunodeficiency syndrome of infancy. In most cases IgA-D represents an isolated immunological disorder, while sometimes it is associated with IgG subclass deficiency or with the presence of autoantibodies. We investigated the pattern of association of IgA-D with DRB1 and DQB1 loci of the HLA region by DNA molecular typing, which allows the identification of previously serologically undefined specificities. We also compared the gene frequency of DRB1 and DQB1 allelic variants between IgA-D subjects with or without serum autoantibodies. Our results indicate that the gene frequency of the DRB1*0102 subtype and of the DRB1*0102, DQB1*0501 haplotype is significantly higher in IgA-D than in the general population. Furthermore, the IgA-D subjects with autoantibodies showed a positive association with DR4 and DR13 subtypes, thus supporting the hypothesis that genetic factors are also involved in the association between IgA-D and autoantibodies.

Alleles↗
PubMed1994

Interleukin-12 induces tyrosine phosphorylation and activation of 44-kD mitogen-activated protein kinase in human T cells.

Interleukin-12 (IL-12) is a novel cytokine that enhances numerous functional activities of human T cells and natural killer (NK) cells. The present studies were undertaken to characterize some of the early signaling events following IL-12 stimulation of mitogen-activated normal T cells. In these cells, IL-12 induces rapid tyrosine phosphorylation of proteins of 21, 44, and 54 kD. However, IL-12 does not induce tyrosine phosphorylation in normal resting T cells. In conjunction with increased tyrosine phosphorylation of several substrates, IL-12 stimulation resulted in increased in vitro kinase activity of immunoprecipitated tyrosine phosphorylated proteins. The 44-kD protein has been characterized as one isoform of the mitogen-activated protein (MAP) kinase family. Increased tyrosine phosphorylation of MAP kinase following IL-12 stimulation was also associated with enhanced enzymatic activity of this protein in vitro as measured by myelin basic protein phosphotransferase assay. These studies identify MAP kinase as one of the intracellular elements of the IL-12 signaling pathway in human T cells.

Enzyme Activation↗
PubMed1993

Fc gamma RIIIA-mediated signaling involves src-family lck in human natural killer cells.

The cell surface receptor for IgG Fc domain (Fc gamma RIIIA, CD16) is present as a multimeric complex on human NK cells and is essential for antibody-dependent cellular cytotoxicity. Although CD16 engagement induces tyrosine phosphorylation of several substrates, the intracytoplasmic domains of the CD16 molecule lack intrinsic protein tyrosine kinase consensus sequences. We report here that, in human NK cells, engagement of the CD16 receptor induces tyrosine phosphorylation of p56lck tyrosine kinase. CD16 triggering through anti-receptor antibody enhances in vitro kinase activity of phosphotyrosyl proteins and autophosphorylation activity of anti-lck immunoprecipitates. Similar results were obtained after stimulation with IL-12. In vivo labeling experiments showed that CD16 cross-linking primarily induces in vivo phosphorylation of p56lck at the tyr-394 autophosphorylation site. Using in vitro kinase assay of CD16 immunoprecipitates from lysates of human NK cells, we demonstrated that a phosphorylated protein of 62 to 65 kDa was co-precipitated with CD16. Reprecipitation experiments also suggested that a small amount of p56lck may interact with this complex. These results indicate that CD16 triggering involves p56lck and that this kinase is therefore involved in the signaling pathways regulating NK cell cytolytic functions. However, additional kinases not yet identified are also likely to play a role in the early signaling events through CD16.

Antibody-Dependent Cell Cytotoxicity↗