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Biomedical subjects

A Albertini

Publications and source records attributed to A Albertini.

At least 109 records · Page 6Linked to original sources
PubMed1992

Monoclonal antibody-based enzyme-linked immunosorbent assays (ELISA) for the measurement of vitamin K-dependent protein S: the effect of antibody immunoreactivity on plasma protein S antigen determinations.

Two monoclonal antibodies (Mabs) specifically directed to human protein S (PS) - named 5E9E9 and 3B10.25 - were produced and their properties compared to those of 2 previously characterized anti-PS-Mabs (HPS-2 and S10). 3B10.25, similar to S10, was directed to the calcium-free conformation of PS and had virtually identical affinity for free and C4b-binding protein (C4b-BP)-bound PS; 5E9E9 similar to HPS-2, had no calcium-dependency and was selectively directed to free PS. All Mabs were equally reactive to freshly purified and thrombin-cleaved PS. To evaluate the influence of C4b-BP bound PS on PS antigen determinations, ELISA systems employing the four Mabs individually as capture antibody (Ab) and peroxidase-conjugated polyclonal anti-PS IgG as detecting Ab were developed and compared to immunoelectrophoresis (EIA) and to an ELISA employing polyclonal anti-PS IgG as capture and detecting Ab, in the determination of PS in purified systems and in plasma. With all the ELISAs there was parallelism of dilution curves obtained with normal plasma and purified PS; however, supplementation of plasma with purified C4b-BP resulted in loss of parallelism when employing the Mabs directed to free PS as capture Ab. Influence of high C4b-BP on PS antigen determinations was confirmed in a series of plasma samples from patients with C4b-BP levels ranging from 70% to over 200%. Compared to the values obtained with the S10- or 3B10.25 - based ELISAs - which were similar despite a 10-fold difference in sample dilution - plasma PS was underestimated by the ELISAs employing 5E9E9 or HPS-2 while it was overestimated by EIA.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗
PubMed1992

Paradoxical effect of long-term treatment of nifedipine on total ischemic load in patients with stable angina pectoris.

In 50 patients with stable effort angina the effect of three drugs, metoprolol, nifedipine, and diltiazem was assessed by analyzing exercise stress test response and ambulatory ECG recordings. Both metoprolol and diltiazem caused a significant increase in time to ischemic threshold during exercise and a significant decrease of maximum ST-segment depression (during exercise and ambulatory ECG monitoring) and in the average number of daily ischemic episodes. Only metoprolol significantly reduced heart rate and rate-pressure product at the ischemic threshold during exercise. In the group of patients treated with nifedipine no significant improvement was observed in exercise tolerance or in number of ischemic episodes/24 h. Moreover, the subset of nonresponders in the two methods was larger than in the other two groups. In some of these patients a clearcut worsening of total ischemic load was observed, despite the control of symptoms. This adverse effect might be attributed to the different consequences of the vasodilatory effect of nifedipine on blood flow through stenosed vessels.

Adult↗
PubMed1992

Evaluation of hepatitis delta virus RNA levels during interferon therapy by analysis of polymerase chain reaction products with a nonradioisotopic hybridization assay.

We developed a nonradioisotopic assay for detection of hepatitis delta virus RNA in serum by combining reverse transcription of RNA, polymerase chain reaction of the resultant complementary DNA and enzyme linked immunoassay detection of the polymerase chain reaction products using a monoclonal antibody specific for double-stranded DNA. This DNA enzyme immunoassay had a limit of detection of cloned hepatitis delta virus RNA similar to that of standard PCR followed by Southern-blot hybridization (approximately 10 copies/sample) and was 10(3) to 10(4) times more sensitive than direct dot-blot hybridization (approximately 10(5) copies/sample). Serial serum samples from six patients with chronic hepatitis delta virus infection undergoing interferon therapy were analyzed by reverse transcription-polymerase chain reaction followed by both standard hybridization and DNA enzyme immunoassay. The results of both methods were comparable, revealing disappearance of hepatitis delta virus RNA after 3 to 6 mo of therapy in three patients, two of whom had also a significant decrease in ALT activity. The DNA enzyme immunoassay test is therefore a potentially useful method for therapeutic monitoring in chronic hepatitis delta virus infection and may contribute to a wider application of polymerase chain reaction in clinical laboratories.

Adult↗
PubMed1992

Antibodies for denatured human H-ferritin stain only reticuloendothelial cells within the bone marrow.

Human H-ferritin homopolymer was denatured in sodium dodecyl sulphate and injected in mice to obtain antibodies for dissociated H-subunit. The antisera and Moabs obtained were specific for the denatured H-chain with no cross-reactivity with assembled ferritins in immunoblotting experiments. In contrast the Moabs for native recombinant H-ferritin are specific for the assembled ferritin molecules with weak cross-reactivity with the denatured H-subunits. The epitope recognized by one of the anti-denatured H-chain Moabs was mapped on the C-terminal helix of ferritin. The antibodies were used to study H-ferritin conformation in cells. In immunocytochemistry experiments the antibodies for denatured H-ferritin stained HeLa and K562 cells weakly, with a different intensity and pattern to those obtained with anti-native H-ferritin antibody. In human bone marrow smears the anti-denatured ferritin antibodies stained only reticuloendothelial cells, and did not recognize the H-ferritin rich immature erythroblasts. It is concluded that assembled and denatured H-ferritins are immunogenically distinct, and that erythroid and reticuloendothelial cells within the bone marrow contain H-ferritin in different conformations.

Antibodies, Monoclonal↗
PubMed1992

Serodiagnosis of Helicobacter pylori-associated gastritis with a monoclonal antibody competitive enzyme-linked immunosorbent assay.

Forty-nine monoclonal antibodies against Helicobacter pylori were screened to investigate their capacity to be used in enzyme-linked immunosorbent assay (ELISA) competitive systems for the serodiagnosis of Helicobacter pylori infection. On the basis of the inhibition pattern showed by the sera of five infected patients, the antibodies were subdivided into five groups. The immunoblotting analysis showed that the antibodies recognized a total of nine different antigenic determinants. In a study of the reaction of the antibodies with 12 isolates of H. pylori a total of 9 antigenic profiles were identified. Two monoclonal antibodies, HpN44 and HpN45, which recognized a 64-kD protein, were inhibited by all 5 positive sera. Antibody HpN45 was labeled with horseradish peroxidase, and the competitive ELISA was compared with an ordinary indirect ELISA in a study of 102 patients undergoing gastroscopy. Seventy-three patients proved to be infected by H. pylori according to urease or histologic tests. The sensitivity and specificity were 90.4% and 89.6%, respectively, for the indirect ELISA and 100% and 89.6% for the HpN45 competitive assay. The three patients who were 'false seropositive' with both serologic tests had atrophic gastritis. The high diagnostic performance and simplicity of the HpN45 monoclonal competitive ELISA make it suitable for routine serodiagnosis of H. pylori infection.

Antibodies, Monoclonal↗
PubMed1992

Non-radioisotopic methods for DNA probes.

We have recently developed a new colorimetric method, DNA enzyme immunoassay (DEIA), for detecting specific hybrids of complementary nucleic acids. This technology is based on an antibody that selectively recognizes double, but not single-stranded DNA. The molecule does not react with a specific probe immobilized on microwells through an avidin-biotin bridge, nor with non-specific amplified sequences, since they are removed by washing. The antibody reveals the hybridization event, independently of the DNA sequences and, for this reason, the method is broadly applicable and extremely versatile. Although we chose a format based on the immobilization of the probe through an avidin-biotin interaction, DEIA assay can also be applied to other analytical schemes that do not require any modification of the probe. Most importantly, the test has an ELISA format and is rapid and convenient for processing large numbers of samples. This technology has been applied, in our laboratory, to different areas, including virology, genetic and basic immunology. The DEIA assay has been successfully used to detect the presence of hepatitis B (HBV), hepatitis C (HCV) and hepatitis delta virus (HDV) sequences in serum of patients, to discriminate different HLA alleles, to identify mutations in the Cystic Fibrosis gene, and to investigate the role of the T cell receptor in some immunological diseases. The results obtained in all our experiments demonstrated that the advantages offered by the assay do not penalize its analytical performance as compared to conventional Southern blot.

Colorimetry↗
PubMed1991

Progestin regulation of alkaline phosphatase in the human breast cancer cell line T47D.

In T47D breast cancer cell line, progestin (R5020) induces de novo synthesis of an alkaline phosphatase enzyme. Based on inhibitor profiles and antigenic specificity, it is apparent that this enzyme belongs to the class of membrane-associated tissue-unspecific alkaline phosphatases. Enzyme induction was uniquely specific to progestins and not altered by other steroid hormones or synthetic analogues. The progestin induction of the tissue-unspecific alkaline phosphatase was time and dose dependent. The protein synthesis inhibitor cycloheximide blocks the enzyme synthesis and tunicamycin blocks the enzyme activity, showing that the induction was new synthesis of protein in its complete glycosylated form and not activation of a preexisting enzyme. To our knowledge this is the first report of progesterone-induced expression of a tissue-unspecific alkaline phosphatase gene of such magnitude (about 30- to 100-fold) in a progesterone-responsive tissue.

Acid Phosphatase↗
PubMed1991

Analysis of X-chromosome inactivation in X-linked immunodeficiency with hyper-IgM (HIGM1): evidence for involvement of different hematopoietic cell lineages.

The pattern of X-chromosome inactivation was analyzed, by means of two different DNA probes (pSPT-PGK and M27 beta), in several cell lineages derived from females belonging to a pedigree with X-linked immunodeficiency with hyper-IgM (HIGM1). Non-random X-chromosome inactivation was demonstrated in T cells, B cells, and neutrophils, but not in fibroblasts, of obligate carriers, suggesting that different hematopoietic cell lineages are primarily involved in HIGM1. Preferential inactivation of the paternally derived X-chromosome was demonstrated by analysis of segregation of the alleles defined by the pSPT-PGK and M27 beta probes. The possibility that the HIGM1 mutation may confer a proliferative and/or differential advantage to hematopoietic precursors carrying the mutated allele on the active X-chromosome is discussed.

B-Lymphocytes↗
PubMed1991

Analysis of X-chromosome inactivation and presumptive expression of the Wiskott-Aldrich syndrome (WAS) gene in hematopoietic cell lineages of a thrombocytopenic carrier female of WAS.

We report on a thrombocytopenic female belonging to a pedigree with the Wiskott-Aldrich syndrome (WAS). Restriction fragment length polymorphism (RFLP) analysis with probe M27 beta, closely linked to the WAS gene, demonstrated that she is a carrier of WAS. Both small-sized and normal-sized platelets were present, suggesting that, unlike the vast majority of WAS carriers, she does not manifest nonrandom X-chromosome inactivation in the thrombopoietic cell lineage. Study of X-chromosome inactivation by means of RFLP and methylation analysis demonstrated that the pattern of X-chromosome inactivation was nonrandom in T lymphocytes, but random in granulocytes. While this is the first complete report on the occurrence of thrombocytopenia in a carrier female of WAS as the result of atypical lyonization, it also suggests that expression of the WAS gene occurs at (or extends up to) a later stage than the multipotent stem cell along the hematopoietic differentiation pathway.

Dosage Compensation, Genetic↗
PubMed1991

Helicobacter pylori infection induces antibodies cross-reacting with human gastric mucosa.

The authors' previous observation that many of the monoclonal antibodies against Helicobacter pylori cross-react with the cells of the human gastric mucosa prompted them to investigate the possibility that gastric self-antigens cross-reacting with H. pylori could be involved in the immune response against this organism. It was found that three antibodies against H. pylori, CB-4, CB-10, and CB-14, that cross-react with the human gastric mucosa also intensely cross-reacted with murine gastric epithelial cells. A strong reaction against autologous mucosa was also evident in the sera of mice immunized with H. pylori but not with other bacteria. A serological study performed in a group of 82 patients undergoing gastroscopy showed that the presence of seropositivity against H. pylori was strongly correlated with the presence of autoantibodies against human antral gastric mucosa. This activity was neutralized after absorption of the sera with H. pylori but not with other gram-negative bacteria. The antibodies in the mouse and in the human did not react with other segments of the gastrointestinal tract or with most of the other organs. Mice bearing hybridomas secreting a cross-reacting antibody (CB-4) had histopathologic abnormalities in their stomachs. These lesions were absent in the stomachs of mice bearing hybridomas secreting a non-cross-reacting antibody (CB-26). It was concluded that H. pylori infection can stimulate antibodies cross-reacting with gastric autoantigens and that this immunologic mechanism may represent a pathogenic link between H. pylori and gastritis.

Animals↗
PubMed1991

An immunoassay for specific amplified HCV sequences.

The direct detection of viraemia could improve greatly the efficacy of presently available assays. Due to its sensitivity, the polymerase chain reaction represents the method of choice for direct detection of viral nucleic acid. However, the clinical application of this method is hampered by the requirement of hybridization with radioactively labelled probes. In this study we demonstrate that HCV cDNA, amplified by the polymerase chain reaction from both liver tissues and sera, can be detected specifically by a new non-radioisotopic method, DNA enzyme immunoassay, that is based on an antibody that selectively recognizes double, but not single-stranded DNA. The assay reveals the hybridization events, independently from the DNA sequences, and therefore can be used with any combination of primers and probes. Most importantly, the method has a conventional ELISA format and is compatible with standard facilities of clinical laboratories. The availability of this new approach for revealing amplified sequences may facilitate greatly the use of PCR as the method of choice for early diagnosis of HCV infection.

Adult↗
PubMed1991

Role of oxygen free radicals in ischemic and reperfused myocardium.

In recent years there has been considerable interest concerning the role of oxygen radicals in myocardial ischemia and reperfusion injury. The sequential univalent reduction of oxygen gives rise to very reactive intermediate products. Normally, the tissue concentration of these intermediate products of oxygen is limited and the aerobic myocardium survives because of the existence of a delicate balance between the generation of the various oxidants and the maintenance of the antioxidant defense mechanism. Several possible sources have been identified for the production of active oxygen species after ischemia and reperfusion and these sources may be mutually interactive. The ability of scavengers of oxygen free radicals, including vitamin E, to improve mechanical, mitochondrial, and sarcoplasmic reticulum function in animal models of ischemic-reperfusion injury also suggests that oxygen free radicals are partly responsible for myocardial damage in these models, although caution in the interpretation of these data is necessary.

Animals↗
PubMed1991

Renal and hemodynamic effects of atrial natriuretic peptide infusion are not mediated by peripheral dopaminergic mechanisms.

The possible involvement of peripheral dopaminergic mechanisms in the action of atrial natriuretic peptides was investigated in 10 subjects by administering 200 micrograms h-ANP 99-126 intravenously for 30 min during treatment with 50 mg carbidopa, a peripheral inhibitor of dopamine synthesis, every 8 h, or during placebo. Atrial natriuretic peptide (ANP) infusion during placebo was associated with a significant increase of diuresis, natriuresis, kaliuresis, urinary noradrenaline, and dopamine excretion. Plasma aldosterone significantly decreased. Blood pressure was slightly reduced. The administration of carbidopa significantly reduced urinary dopamine excretion but did not modify natriuresis, diuresis, indexes of adrenergic and renin-aldosterone system activity, blood pressure, or heart rate, both in basal conditions and in response to ANP infusion. We conclude that the effects of exogenous ANP administration are independent from dopaminergic mechanisms that involve the synthesis of dopamine outside the central nervous system, particularly in the kidney.

Adult↗