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C Negri

Publications and source records attributed to C Negri.

At least 55 records · Page 3Linked to original sources
PubMed1992

Monoclonal antibodies to human DNA topoisomerase I and the two isoforms of DNA topoisomerase II: 170- and 180-kDa isozymes.

Several monoclonal antibodies of different isotypes specific to human DNA topoisomerase I, to 170- and 180-kDa DNA topoisomerase II isozymes, were produced and characterized. The specificity of monoclonal antibodies was confirmed by comparison with polyclonal antibodies by Western blot, by immunoprecipitation of enzyme activity, and by immunoprecipitation of DNA topoisomerases with characterized polyclonal antisera. Morphological studies performed by immunofluorescence indicate that the three groups of monoclonal antibodies (MoAbs) stain the nucleus with characteristic patterns, which can be compared with those obtained with polyclonal antibodies. In particular the MoAbs to the 100-kDa DNA topoisomerase I stain the nucleolus and the nucleoplasm; the MoAbs to 170- and 180-kDa DNA topoisomerase II give completely distinct intranuclear patterns: those to the 170-kDa protein stain mainly the nucleoplasm, whereas those to the 180-kDa protein stain only the nucleolus. The two DNA topoisomerase II isozymes clearly exhibit fluctuations in their expression during cell growth: the 170-kDa isozyme is more abundant during the logarithmic phase of growth, while the 180-kDa isozyme is mainly present during the plateau phase of growth.

Antibodies, Monoclonal↗
PubMed1992

The 180-kDa isoform of topoisomerase II is localized in the nucleolus and belongs to the structural elements of the nucleolar remnant.

Monoclonal antibodies raised against two isoforms (170 and 150/180 kDa) of DNA topoisomerase II showed distinct fluorescence patterns in HeLa cells in different moments of the cell cycle (C. Negri et al., 1992, Exp. Cell Res. 200, 452-459). The ultrastructural distribution of the 150/180-kDa isoform, which in immunofluorescence showed a localization into the nucleolar region, has been analyzed by electron microscopy with a gold-conjugated secondary antibody in HeLa and K562 cells. The results indicate that this isoform of the enzyme is exclusively localized in the nucleolus, mainly in the dense fibrillar component, while the nucleoplasm of interphase cells and the chromosomes of mitotic cells are completely negative. The antibody also reacts with the nucleolus of isolated nuclei and with the nucleolar remnant of purified nuclear matrices. A quantitative evaluation of the label distribution indicates that the percentage of label in the nucleolar remnant of isolated matrix is almost identical to that of the nucleolus in whole cells. The interaction with the insoluble proteins of the isolated nuclear matrix is also demonstrated by quantitative immunoblotting in which the MoAb specifically stains a unique band corresponding to the 150/180-kDa isoform of topoisomerase II. The localization of the 150/180-kDa isoform of topoisomerase II in the nucleolar remnant strongly suggests that it represents a structural element for the spatial organization and for the regulation of transcription of the ribosomal genes.

Blotting, Western↗
PubMed1991

Factor(s) required by EBV transformed lymphocytes to grow under limiting dilution conditions.

IL-6 was demonstrated to promote growth of EBV transformed lymphocytes. However IL-6 was ineffective at promoting growth of EBV transformed lymphocytes cultured at the single cell level under limiting dilution conditions. On the contrary, HECS, which is known to contain IL-6, supported very efficiently the growth of 1-2 EBV transformed cells. When IL-6 was removed from HECS, by using specific antibodies, no reduction in HECS activity was observed, indicating that probably more than one growth factor is required to support the growth of EBV transformed cells cultured at very low cell numbers in the absence of feeder cells.

Cell Division↗
PubMed1991

Synthetic and natural factors promoting production of murine and human monoclonal antibodies.

Human endothelial culture supernatant (HECS) contains factor(s) which promote the growth and the stability of hybridoma cells, and in these respects is superior to the commonly used feeder cells. In particular: HECS increases the recovery of hybridomas after fusion as compared to that in the presence of feeder cells; HECS can substitute feeder cells supporting the growth of hybridomas at the single-cell level under limiting dilution conditions; HECS prolongs the stability of human-mouse hybridomas producing human immunoglobulins (Ig). The active principle which is present in HECS can be different from IL-6. Furthermore the effects of a polyamine derivative, carboxyethyl gamma-aminobutyric acid (CEGABA), were studied on the growth of hybridomas and Epstein-Barr Virus-transformed cell lines. CEGABA enhances the growth of hybridomas through all the steps of hybridoma technology and induces the formation of a large number of EBV-transformed lymphocytes, when added to the culture medium immediately after EBV infection. However, CEGABA shows only a moderate effect on the stability of EBV-transformed cell lines over time, and does not effect the growth of stabilized cell lines. It is possible that CEGABA acts on cells other than EBV-transformed lymphocytes (in fact, after EBV infection all types of mononuclear cells from the blood are present in the culture) and indirectly promotes the growth of EBV-transformed lymphocytes.

Animals↗
PubMed1990

Antibodies from patients with rheumatoid arthritis and systemic lupus erythematosus recognize different epitopes of a single heterogeneous nuclear RNP core protein. Possible role of cross-reacting antikeratin antibodies.

Antibodies to recombinant heterogeneous nuclear RNP core protein A1 were detected in sera from 27 of 58 patients with rheumatoid arthritis (RA) and from 7 of 31 patients with systemic lupus erythematosus, by immunoblotting and enzyme-linked immunosorbent assay. Protein A1 consists of 2 distinct domains: The N-terminal sequence is identical to a single-stranded DNA binding protein termed UP1, and the C-terminal domain shows a partial homology with keratin. All 7 A1-positive systemic lupus erythematosus sera reacted with UP1, whereas 9 of the 27 A1-positive RA sera did not. In RA, anti-A1 activity was significantly associated with antikeratin antibodies (AKA); these antibodies were present in 23 of 27 A1-positive sera and 10 of 31 A1-negative sera (P less than 0.01). Immunoabsorption with recombinant protein A1 resulted in a significant reduction of AKA titers in 6 of 10 RA sera tested, suggesting that AKA from RA patients may cross-react with the C-terminal portion of the heterogeneous nuclear RNP protein A1.

Adolescent↗
PubMed1990

Autoantibodies to poly(ADP-ribose)polymerase in autoimmune diseases.

Antibodies to various nuclear proteins are frequently found in sera of patients affected by connective tissue diseases and other autoimmune diseases. We investigated the specificity of circulating autoantibodies to poly(ADP-ribose)polymerase (pADPRP) in different autoimmune and connective tissue diseases: Systemic Lupus Erythematosus (SLE), Rheumatoid Arthritis (RA), Progressive Systemic Sclerosis (PSS), Sjogren's Syndrome (SS), Undifferentiated Connective Tissue Disease (UCTD), Cryptogenic Fibrosing Alveolitis (CFA) and Sarcoidosis. pADPRP was purified from calf thymus. Antibody specificity was detected by ELISA, western blot and enzyme activity precipitation. Positive values (mean O.D. values + 3 S.D. of 36 normal controls) were obtained in 7/15 SLE patients, 1/18 RA patients, 1/30 PSS, 3/14 SS, 0/5 UCTD, 5/21 CFA and 4/25 Sarcoidosis. The positive sera also recognized the pADPRP protein when tested by western blot. Furthermore the enzyme activity was inhibited after immunoprecipitation by some highly positive sera.

Adolescent↗
PubMed1989

Antibodies to hnRNP core protein A1 in connective tissue diseases.

We investigated the specificity of circulating autoantibodies to a heterogeneous nuclear ribonuclear protein A1 (hnRNP A1), obtained by recombinant DNA technique, in different rheumatic diseases: systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), scleroderma, primary Sjogren's syndrome (SS), idiopathic Raynaud (IR), mixed connective tissue disease (MCTD), and healthy donors. All sera were tested by ELISA on hnRNP A1 protein. Positive values were obtained in 22% SLE, 19% scleroderma, 10% IR, 40% (2/5) MCTD, 5% SS, and 50% RA patients. The majority of patients reacted with the aminoterminal part (UP1) of hnRNP A1; however, some RA patients reacted also with the carboxy-terminal part that shows partial homology with keratin. Therefore, hnRNP A1 (UP1) can be considered a target of antinuclear autoimmunity in various rheumatic disorders.

Autoantibodies↗
PubMed1989

Clinical and immunological aspects of HIV infection in drug addicts.

Intravenous drug users (IVDUs) account for more than 64% of the total AIDS cases in Italy. The IVDUs' seropositivity rate is greater than 70% in Milan and greater than 50% in the main cities of Italy. The first evidence of seropositivity in this population dates back to 1979. In a cohort study performed in Milan the rate of progression to overt AIDS among IVDUs was 6% in 3 years (1984-1987). At presentation, more than 75% of the subjects had CD4+ cell counts higher than 400/mm3 (mean 631, median 528, mode 465). These values are significantly higher than those observed in the same population in New York, the only American city with HIV-infection spread comparable to that observed in Milan. The probability of having CD4+ cell counts lower than 400, 300, and 200/mm3 in relation to the length of follow-up was, respectively, 50, 40, and 2% after 36 months from presentation. At the same end point, subjects presenting less than 400 CD4+ cells at entry had 30% probability of falling under 200 cell/mm3. The pattern of CD4+ cells, as much as the low percentage of yearly progression to overt AIDS, is probably related to the recent, even if rapid, spread of infection among IVDUs in Italy. The clinical features of overt AIDS present some differences between IVDUs and other at-risk groups. Among U.S. IVDUs with AIDS, Kaposi's sarcoma is infrequent (2.9% vs 27.7% in homosexual men) while mycotic infections such as deep candidiasis and cryptococcosis are significantly more frequent. The same pattern has been observed in our case file in Milan: esophageal candidiasis represents the most frequent cause of diagnosis of overt AIDS. Mycotic infections, overall, are more frequent than in U.S. IVDUs. The increased rate of mycotic infections among IVDUs might be justified by altered functions of nonspecific immunity, such as PMNL killing and phagocytosis of Candida albicans spores, impaired in HIV-infected IVDUs, but generally normal in infected subjects belonging to the other at-risk groups.

CD4-Positive T-Lymphocytes↗
PubMed1989

Experience with itraconazole in cryptococcosis and aspergillosis.

Cryptococcosis and aspergillosis in immunocompromised patients are extremely difficult clinical conditions to manage and treatment with available antifungal drugs often fails. Itraconazole, R-51211, Janssen Pharmaceutica, a new orally absorbed triazole, is a possible alternative drug which is potentially effective and nontoxic. Preliminary experience with 28 patients, eight with cryptococcosis and 20 with aspergillosis, is reported. Of these patients, 16 were immunocompromised (seven with the acquired immune-deficiency syndrome (AIDS), five heart transplant recipients and four with leukaemia or lymphoma). Overall, results of treatment were good (18 in remission, four markedly improved, four moderately improved and two failed). Prevention of relapses of cryptococcosis was obtained in all patients with AIDS on long-term itraconazole monotherapy (3 mg/kg). Treatment of invasive aspergillosis required a higher dosage (about 5 mg/kg) and prolonged administration. Besides its efficacy this antifungal agent allowed outpatient management.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Autoantibodies to DNA topoisomerase II in cryptogenic fibrosing alveolitis and connective tissue disease.

Sera from patients with autoimmune lung and connective tissue diseases were investigated for antibodies to topoisomerase II. Anti-topoisomerase II antibodies were detected by ELISA in 37% of sera from patients with cryptogenic fibrosing alveolitis (CFA), in one (8%) case of sarcoidosis and in 31% of sera from systemic lupus erythematosus (SLE) patients. Sera from rheumatoid arthritis, juvenile rheumatoid arthritis, progressive systemic sclerosis, Sjögren's syndrome and undifferentiated connective tissue disease were negative. CFA and sarcoidosis sera strongly reacted in immunoblotting with a 170 kD protein, also recognized by rabbit antiserum to recombinant topoisomerase II, while SLE sera presented a weak reaction. Pre-adsorption with dsDNA dramatically decreased the topoisomerase II binding in ELISA by the most positive SLE serum, but did not affect the binding by the most positive CFA serum, thus indicating that anti-topoisomerase II reactivity of SLE sera is probably due either to cross-reacting antibodies or, in part, to minor DNA contamination of our enzyme preparation. The determination of DNA topoisomerase II relaxation activity, performed after incubation with antibody-positive sera, showed that only CFA sera precipitate enzymatic activity. The finding that CFA presents antibodies to an enzyme essential to cell survival stresses the role of autoimmunity in the pathogenesis of idiopathic pulmonary fibrosis. This may offer further insight into the cause of autoimmune disease and prove a valuable tool in the study of enzyme molecular biology.

Adolescent↗
PubMed1989

Morphogenesis, evolution and prognostic significance of lymphatic tissue lesions in HIV infection.

Morphological changes in lymph node biopsies of HIV-infected patients can be classified in four stages, based upon the degree of damage to follicular structures: (1) follicular hyperplasia, (2) follicular lysis, (3) follicular atrophy and (4) follicular and lymphocytic depletion. To define the relative usefulness of morphological, clinical and immunological findings for prognostic purposes, we followed the clinical evolution of 86 biopsied HIV+ patients for a period ranging from 1 to 56 months. A relatively good correlation between histological and clinical findings, at the time of biopsy, was observed. Statistical analysis confirmed the prognostic value of the histological features for clinical deterioration, progression to AIDS and survival. Moreover, histological findings gave more reliable prognostic information than clinical values. Our data suggest that lymph node biopsy can be utilized for prognostic purposes in the evaluation of the progression of the disease and effectiveness of antiviral therapeutic trials.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Focal lymphocytic myocarditis in acquired immunodeficiency syndrome (AIDS): a correlative morphologic and clinical study in 26 consecutive fatal cases.

In 26 consecutive cases with acquired immunodeficiency syndrome (AIDS) the main cardiac findings were Kaposi's sarcoma in 2 cases, microfocal myocardial abscess in 1, subendocardial infarct necrosis in 2, contraction band necrosis in 13, lymphocytic myocarditis in 9, intramyocardial lymphocytic infiltrates without myocell necrosis in 7 and epicardial lymphocytic infiltrates in 4. No patient had congestive heart failure. However, two-dimensional echocardiography performed in eight patients demonstrated functional abnormalities in six (fractional shortening ranging from 18 to 30%, globular shape, hypokinesia, mild ventricular dilation). Four of these six patients had lymphocytic myocarditis and two had lymphocytic infiltrates in the myocardium and epicardium without myocell necrosis. No lymphocytic infiltrates were seen in the two cases with a normal echocardiogram. Quantitative analysis indicated that involvement of the heart by lymphocytic myocarditis is inadequate in itself to explain dysfunction. It remains to be established 1) whether lymphocytic myocarditis is a possible indication of a more widespread molecular disorder, and 2) what its eventual relation with dilated cardiomyopathy will be.

Acquired Immunodeficiency Syndrome↗
PubMed1988

T-lymphocyte subsets and delayed type hypersensitivity as classification parameters for HIV infection among drug-addicts.

HIV selectively infects T helper lymphocytes, which play an essential role in cell-mediated immunity mechanisms. Impairment of these mechanisms can be evaluated, other than by clinical parameters, by testing lymphocytic subsets and cutaneous delayed type hypersensitivity. All these indices are used in the Walter Reed Foundation (WR) staging system, which includes the different stages of HIV infection. In our study we investigated the above mentioned parameters in a series of 180 HIV positive PDAs. A classification of the same patients according to WR's criteria was also designed. Of our patients, 46.1% resulted normoergic, 27.2% hypoergic and 26.7% anergic. Of all normoergic subjects, 83.7% (with more than 400 OKT4+ cells/mmc) could be assigned to the WR2 and 16.3% (with less than 400 OKT4+ cells/mmc) to the WR3 staging group. Among the hypoergic patients, only 34.7% were assignable to the WR4 group, whereas the majority (65.3%) had more than 400 OKT4+ cell/mmc. Even among the anergic group, 62.5% did not fit the WR5 stage, exhibiting an OKT4+ level higher than 400/mmc. In the latter 2 groups (referred to as D and E), T helper lymphocyte counts were performed at regular intervals; however, only the ones followed-up for at least 6 months were evaluated. OKT4+ cells were shown to decrease more frequently and more rapidly in the anergic than in the hypoergic patients, which points to cutaneous anergy as representing an early sign of impairment of cell-mediated immunity.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Human immunodeficiency virus (HIV) seropositivity in intravenous (i.v.) drug abusers in three cities of Italy: possible natural history of HIV infection in i.v. drug addicts in Italy.

The prevalence of human immunodeficiency virus (HIV) antibodies and the symptoms induced [persistent generalized lymphadenopathy (PGL), AIDS-related complex (ARC), acquired immunodeficiency syndrome (AIDS)] was evaluated in several groups of intravenous (IV) drug abusers in three large Italian cities (Milan, Bologna, and Rome). The earliest evidence of seropositivity in sera collected from patients with acute viral hepatitis dates back to 1979 in Milan and to 1981 in Bologna with peaks in 1983 in both cities. In two groups of IV drug addicts on methadone-maintenance treatment at assistance centers, the prevalence of seropositivity differed sharply between Rome (33.3%) and Milan (69.3%) in 1985. Rates of seroconversion were also found to be higher in Milan than in Bologna and Rome. When a population of IV drug abusers voluntarily attending centers for surveillance of AIDS and/or ARC were investigated, high levels (range 55.2-81.5%) of seropositivity were found in the three cities. ARC prevalence among seropositives was very high (range 48.1-64.2% in 1985) in the three cities. The evolution rate to AIDS in Milan was higher among those attending a center for AIDS surveillance (7.4%) than among those attending an assistance center for methadone treatment (0.9%). These data are compatible with the hypothesis that virus infection among IV drug abusers originated in and then spread widely in Northern Italy (Milan first and then Bologna). Both the first appearance and subsequent spread of virus infection are in keeping with the reported occurrence of AIDS cases in the corresponding three regions of Milan, Bologna, and Rome.

AIDS-Related Complex↗
PubMed1987

Role of PMN's candidicidal activity in the pathogenesis of AIDS-related systemic candidiases.

Phagocytic and fungicidal activity towards C. albicans spores were tested in 9 patients with AIDS-Related Complex (ARC), but without Candida infections, and in 13 patients with AIDS and deep candidiasis. No significant differences were observed between the two mentioned groups as far as PMN's phagocytosis and killing were concerned. PMN's migration in response to a "non-mycotic" chemoattractant was defective in both groups; although, from this point of view, patients with candidiasis were more severely affected. A significant difference was noted, instead, as far as mean T helper values were concerned; in fact, their number was significantly lower in patients with systemic candidiasis than in those with ARC or even AIDS, but oesophageal candidiasis only. In conclusion, defective PMN's activity towards C. albicans spores, as observed in vitro, does not seem in itself to predispose AIDS patients to candidiasis in vivo; mycoses may be rather due to defects of cell-mediated immunity as a whole.

AIDS-Related Complex↗