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Biomedical subjects

S Marcovina

Publications and source records attributed to S Marcovina.

At least 55 records · Page 3Linked to original sources
PubMed1989

Monoclonal antibody 5A binds apolipoprotein B-48 and inhibits the low density lipoprotein-receptor interaction.

In a panel of 10 monoclonal antibodies raised against human LDL we detected three antibodies (named 5A, 6B, and 6E) which recognize both apolipoprotein B-100 and B-48. Antibody 5A inhibited, in a dose dependent manner, the interaction of 125I-LDL with their receptor on human skin fibroblasts. Using thrombolytic fragments, the epitope of antibody 5A was mapped to the carboxy terminal region of apo B-48. MAB 5A was equipotent with MAB Mb 47, an inhibitory antibody whose epitope lies near a putative receptor binding domain of apo B in thrombolytic fragment T2. These findings suggest that areas other than the carboxy terminal portion of apo B-100 may participate in the LDL-receptor interaction, either directly or by determining the exposition of high affinity sites of apo B-100.

Antibodies, Monoclonal↗
PubMed1988

Interaction of LDL, Lp[a], and reduced Lp[a] with monoclonal antibodies against apoB.

Five monoclonal antibodies (2A, 9A, 6B, L3, L7) produced in mice against human apolipoprotein B were investigated by competitive and inhibitive electroimmunoassay (EIA) for their reactivity with low density lipoprotein (LDL), lipoprotein[a] (Lp[a]), and reduced Lp[a]. All of the antibodies reacted with apoB of the different lipoproteins indicated by very similar slopes of the binding curves. None of them gave a positive reaction with apolipoprotein[a]. The amount of apoB required for 50% inhibition of antibody binding varied for the different antibodies and lipoproteins. Antibody 9A showed almost the same affinity for LDL, Lp[a], and reduced Lp[a]. Antibodies 2A and 6B bound about twofold better to LDL and reduced Lp[a] than to untreated Lp[a]. Antibodies L3 and L7 needed nearly threefold higher amounts of Lp[a]-apoB for 50% inhibition of antibody binding than of apoB of LDL and reduced Lp[a]. The amount of apoB required for 50% inhibition of antibody binding was somewhat higher in inhibitive assay than in competitive assay. We suggest that apo[a] covers certain epitopes of apoB in native Lp[a] leading to a reduced reaction with the monoclonal antibodies. However, it could also be that the binding of the [a]antigen to apoB via disulfide bridges causes profound conformational changes of the apoB region exposed to the surface.

Adolescent↗
PubMed1988

Apolipoprotein C-II deficiency: detection of immunoreactive apolipoprotein C-II in the intestinal mucosa of two patients.

Recent data suggest that mutant immunoreactive forms of apolipoprotein C-II (apoC-II) can be detected in the plasma of patients with the apoC-II deficiency syndrome. We studied the possible presence of apoC-II mutants in the plasma of two patients with apoC-II deficiency by immunological means. The patients were hypertriglyceridemic, and apoC-II was undetectable in plasma as determined by radial immunodiffusion, electroimmunoassay, and immunonephelometry. Furthermore, apoC-II was undetectable either by electrophoresis or by immunoblotting in the plasma of the probands, while apoC-II was present in the plasma of their parents, although at less than half-normal concentration. Immunochemical localization of apoC-II, however, showed that the apoprotein could be detected within the enterocytes obtained from the intestinal mucosa of the patients. From these data we conclude that the patients synthesize apoC-II, at least in the intestine.

Apolipoprotein C-II↗
PubMed1987

Production of monoclonal antibodies specific to theophylline-treated lymphocytes.

The T11 molecule is reported to play a key role in T lymphocytes activation. Moreover, theophylline is known to modify the functional properties of T lymphocytes probably inducing early changes in T11 molecule during T cell activation. Aim of our work was to clarify the effect on T lymphocyte surface after in vitro treatment with theophylline. In this paper, we describe the production and the functional properties of several monoclonal antibodies obtained by immunizing Balb/c mice with theophylline treated cells. Some of the monoclonal antibodies reacted only with the theophylline-treated lymphocytes and showed a promitogenic activity, enhancing the expression of T activated cell antigen. These monoclonal antibodies seem to demonstrate the existence of a membrane molecule which appears on lymphocytes surface after a trigger signal occurring in the early stages of T cell activation likely related to the T11 dependent alternative pathway.

Animals↗
PubMed1986

Radial-immunodiffusion assay of human apolipoprotein A-I with use of two monoclonal antibodies combined.

We produced and characterized several monoclonal antibodies directed toward human plasma apolipoprotein A-I. Two of them, A-I-12 and A-I-57, individually precipitated purified or native high-density lipoprotein in agarose gel by double immunodiffusion. Because radial immunodiffusion performed with a single monoclonal antibody gave faint and diffuse rings of precipitation, we developed and optimized working conditions for using these two monoclonal antibodies combined to determine apolipoprotein A-I in human plasma. This combination gave easy-to-measure, clear, sharp rings, and linear and parallel standard curves for HDL3 (the primary standard) and a reference serum (the secondary standard). Moreover, no pretreatment of samples with dissociating agents or detergents is necessary. The assay was complete after overnight incubation, as compared with two to three days when polyclonal antisera were used. Apolipoprotein A-I concentrations as measured in 128 normolipidemic subjects and in 72 patients with various lipid disorders by the radial immunodiffusion technique with monoclonal antibodies (x) compared well (r = 0.882; y = 1.029x-0.036) with those measured by radial immunodiffusion with polyclonal antisera (y).

Antibodies, Monoclonal↗
PubMed1985

Development of a radial immunodiffusion technique employing monoclonal antibodies for apolipoprotein B determination in human plasma.

Twenty monoclonal antibodies obtained from two different fusions of SP2/0-Ag 14 cell line (non-secretor hybridoma) with human plasma low density lipoproteins have been selected. We found that a mixture formed by the 20 monoclonal antibodies was able to form a single precipitin line with human plasma low density lipoproteins by a double gel diffusion technique. Further studies revealed that only two monoclonal antibodies were needed to precipitate low density lipoproteins in gel. However, a minimum of four particular monoclonal antibodies was required to obtain an optimal precipitin ring and a linear standard curve within 24 h using a radial immunodiffusion technique. We have then compared the radial immunodiffusion performed with a monoclonal antibody mixture to those employing conventional goat and rabbit antibodies in terms of plasma apolipoprotein B determinations. The apolipoprotein B values determined by monoclonal antibodies significantly correlate with the values obtained by the technique using goat (r = 0.95; p less than 0.001) and rabbit (r = 0.95; p less than 0.001) antibodies. Our data indicate that a mixture of monoclonal antibodies can mimic conventional antibodies in terms of immunoprecipitation and apolipoprotein B determination.

Animals↗
PubMed1985

Monoclonal antibodies can precipitate low-density lipoprotein. I. Characterization and use in determining apolipoprotein B.

We produced 20 mouse monoclonal antibodies against human plasma low-density lipoprotein (LDL). Individually they failed to precipitate LDL in agarose gel by the double-immunodiffusion technique; collectively they did, or as few as two combined monoclonal antibodies could do so. To mimic polyclonal antibodies in determination of apolipoprotein B (apo B) by radial immunodiffusion, a combination of four particular monoclonal antibodies (clones A, B, C, and D) was necessary. We characterized these four clones with respect to temperature dependency, affinity, total binding to 125I-labeled LDL, and specificity to the different species of apolipoprotein B. Two monoclonal antibodies (B and C) bound 100% of 125I-labeled LDL; clones A and D bound 80% and 87%, respectively. All four clones bound maximally to LDL at 4 degrees C. The affinity constants for clones A, B, C, and D were 0.6, 2.1, 3.8, and 2.3 X 10(9) L/mol, respectively. By the Western blotting technique, the four monoclonal antibodies all reacted with the species B-100 and B-74 of apolipoprotein B, and to various degrees with B-48 and B-26. Radial immunodiffusion (chi) and direct enzyme-linked immunosorbent assay (y) with a mixture of the four monoclonal antibodies gave almost identical results for 70 patients: y = 0.921 chi-2.58; r = 0.933.

1-Propanol↗
PubMed1985

Monoclonal antibodies can precipitate low-density lipoprotein. II. Radioimmunoassays with single and combined monoclonal antibodies for determining apolipoprotein B in serum of patients with coronary artery disease.

We have established four lines of monoclonal antibodies against human low-density lipoproteins (LDL) that, mixed in equal proportions, can precipitate LDL in gel and so can be used for apolipoprotein (apo) B determination in plasma. One monoclonal antibody (clone A), with a relatively low binding affinity to LDL (ka = 0.6 X 10(9) L/mol) and recognizing only two species of apo B, significantly underestimated the concentration of apo B in 74 patients with and 27 without coronary artery disease (CAD). High-affinity monoclonal antibody C (Ka = 3.8 X 10(9) L/mol), which recognized all four apo B species, gave the same value for apo B as determined with the mixture of monoclonal antibodies. The latter results (by radioimmunoassay, y) correlated well with those by radial immunodiffusion (chi): y = 0.994 chi + 0.003 (r = 0.987). The CAD patients showed an increased concentration of apo B as compared to the angiographically documented CAD-negative patients. Except for the values determined by clone B (p = 0.07), the increase was statistically significant (p = 0.002-0.018) for values determined by use of the other clones or their mixture.

Antibodies, Monoclonal↗
PubMed1984

Noncompetitive enzyme-linked immunoassay for apolipoprotein B in serum.

We used a noncompetitive enzyme-linked immunoassay to measure apolipoprotein B (apo-B) concentration in human plasma. Goat anti-lipoprotein B immunoglobulins were adsorbed to the surface of polystyrene balls. After washing, this solid-phase antibody was incubated with antigen (plasma from normal or hyperlipoproteinemic fasting subjects), washed, and then incubated with peroxidase-labeled goat anti-lipoprotein B IgG. After a last washing, we measured the bound label, which provided a direct measurement of the antigen. Under optimized assay conditions, the minimum detectable concentration was 50 ng per assay. The assay may be used to measure apo-B in different lipoprotein fractions (low- or very-low-density) and yields values that compared favorably with those obtained by electroimmunoassay (r = 0.86). The assay offers several advantages over existing techniques: sensitivity, specificity, simplicity, avoidance of radioisotopes, and potential for use with monoclonal antibodies.

Apolipoproteins↗
PubMed1984

Production and immunochemical study of monoclonal antibodies directed against human low density lipoprotein.

The purpose of this work is to produce monoclonal antibodies directed against Human Low Density Lipoprotein (LDL). Because of the importance of an early characterization in isotypes of the monoclonal antibodies we carefully analyzed three different techniques: double gel diffusion, competition ELISA and immunodot isotyping technique. The three methods gave essentially the same results but greatly differed in sensitivity. We are purifying all the IgG monoclonal antibodies by affinity chromatography from mouse ascitic fluid using Protein A-Sepharose. Here we report details of the purification of one of these monoclonal antibodies. Fractions eluted at different pH values displayed multiple bands by isoelectric focusing, which could be stained for proteins and recognized by radiolabelled Protein A with the electroblotting technique.

Animals↗
PubMed1981

Multivariate statistical analysis of quantitative serum protein data in populations of Rwanda.

Data on serum protein levels of four populations from Rwanda were analyzed by multivariate statistical methods to assess their utility as an anthropological tool. These populations consisted of two ethnic groups in two different environments. Seven proteins were considered in the analysis. The total concentration of proteins is intermediate between Italian levels and those of the Binga pygmies of the Republic of Central Africa (RCA). Discrimination between the populations was possible with a 25% misclassification. The major principal components can be interpreted from a medical viewpoint, and show significant differences between the populations.

Black People↗
PubMed1980

Development and improvement of a commercial uric acid enzymatic determination kit on a centrifugal fast analyzer.

The performance of a uric acid determination kit has been evaluated for five months, under routine conditions, in a General Hospital Biochemical Laboratory. An anomalous increment in fresh serum blanks was noted in the kit when first introduced. This interference, probably due to alcohol dehydrogenase contamination, was corrected by addition of 50 mmol/l (NH4)2SO4 to the reagent. Results obtained with this modified reagent correlate perfectly with those obtained with modified kits by Smith Kline Instruments (SKI), and with many other determination methods. Correlations are discussed and explanations for differences in statistical data are offered. Within run and between run precision data are presented. The kit fits perfectly with the needs of centrifugal fast analyzers and discrete micro analyzers, on account of its speed, reliability and precision.

Alcohol Oxidoreductases↗
PubMed1978

Serum protein levels as anthropological markers: a statistical analysis in Binga Pygmies and Italians.

Data on serum protein levels in Binga Pygmies are presented, and these are compared with the levels in healthy Italians and in Italians suffering from liver diseases. Principal Component Analysis carried out on the three groups points out similarities in protein levels between the Pygmies and the Italian Hepatopaths on one hand and between healthy and liver diseased Italians on the other. Discriminant Analyses reveal the important differences between the populations. It is suggested that such analyses of protein levels could serve as tools in population biology.

Adolescent↗
PubMed1976

[Critical observations on changes in gamma-glutamyl-transpepdidase in hepatopathies].

The behaviour of gamma-glutamyl transpeptidase was compared with other serum enzyme activities and functional parameters in a carefully selected and relatively extensive series of patients with liver disease, including alcoholics, in an investigation of the underlying pathogenesis and its clinical expression. Reference. to the literature and to personal data showed that increased gamma-glutamyl transpeptidase levels could be attributed to enzyme induction (caused by drugs or alcohol), liver damage in the broad sense, and intra- or extrahepatic cholestasis. These causes were individually predominant, or nearly so, on occasions, though their concomitance was more common. High levels, however, were not pathognomonic for a given disease. In alcoholism, they were highly indicative, especially if accompanied by GLD changes. They were a virtually constant, early, and typical finding in intra- and extra-hepatic cholestasis, and tended to persist for a time after the resolution of icterus. Lastly, they were an aid in the early diagnosis of aggressive hepatitis and liver cancer.

Alkaline Phosphatase↗