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Biomedical subjects

I Moraru

Publications and source records attributed to I Moraru.

At least 37 records · Page 2Linked to original sources
PubMed1983

Effect of protein A and its fragment B on the catabolic and Fc receptor sites of IgG.

Radiolabeled protein A from Staphylococcus aureus (SpA) injected i.v. into mice and rabbits forms a soluble [(IgG)2-(SpA)1]2 complex (Mr = 684 000) which is identical in composition to that formed by SpA in vitro with an equivalent amount or an excess of IgG. A soluble rabbit IgG-SpA complex injected into a mice or rabbits dissociates completely in vivo and a new complex is formed with the IgG of the recipient animal. The half-life of SpA administered to a mouse or a rabbit is therefore the half-life of the IgG-SpA complex formed in vivo. In mice and rabbits the half-life of the complexes formed is 9 and 30 h, respectively, whereas the half-life of rabbit IgG in these animals is 106 and 153 h, respectively. Fragment B of SpA (fSpA) reacts with IgG of mouse and rabbit and forms an (IgG)1-(fSpA)1 complex. Complexes of identical composition are formed if fSpA is injected i.v. into mice and rabbits. The half-life of the complexes in mice and rabbits are much shorter than those of the corresponding free IgG in these animals (up to 15 times). This result suggests that the binding of fSpA to the CH2 and the CH3 domains of IgG alters the function of the site, which controls the catabolism of IgG and is located in the CH2 domain. By contrast, fSpA does not change the Fc receptor-binding site of IgG, indicating that the Fc receptor site and the catabolic site are unrelated to each other.

Animals↗
PubMed1982

Similarities between rabbit hepatocyte membrane and nuclear envelope as regards the binding of homologous cytophilic IgG.

Nuclei isolated from rabbit liver are able to bind cytophilic monomeric and polymeric homologous IgG while non-cytophilic rabbit IgG are not bound by nuclei even after its aggregation. The present finding suggests that the rabbit hepatocyte nuclear envelope is similar to the liver cell membrane as regards the specific binding of monomeric cytophilic IgG via a selective binding site for the Fc fragment of IgG. Therefore, the Fc receptor is not restricted to the external membrane of the hepatocyte but exists also on the nuclear envelope.

Animals↗
PubMed1982

Receptors for IgA on human thymus cells in myasthenia gravis.

Specific surface receptors for the Fc region of human immunoglobulin A (Fc alpha R) were identified on the thymus cells of all 15 patients affected by myasthenia gravis. A large variation of the percentage of Fc alpha R bearing thymus cells was recorded (9 . 5-66 . 0%; mean value 27 . 9 +/- 17 . 8) the high values being associated in most cases with the thymus hyperplasia and the low values with a lipomatosis of the organ. Even the lowest percentage of Fc alpha R bearing cells recorded in myasthenia gravis are considerably higher than those found in normal subjects (0 . 4-4 . 1; mean value 1 . 8) demonstrating that the expression of Fc alpha R on the thymus cells is the consequence of the disease. No attempts were made to identify the cell population bearing Fc alpha R but indirect results indicate that the cells belong to E-rosette forming population, and, in some cases, to a null cell population devoid of the ability to form E and EAC rosettes, Fc alpha R can bind various IgA ligands and the binding is confined to a small fraction of IgA (not more than 5%) considered as cytophilic IgA.

Absorption↗
PubMed1981

Simultaneous detection of two different cell surface antigens by electron microscopy by means of multivalent hybrid antibody with double specificity.

Multivalent hybrid antibody (MHA) complexes with dual specificity were prepared by combining two antibodies of different specificities, one against ferritin (Fer), the other against horseradish peroxidase (HRP), with protein A of Staphylococcus aureus (SpA). Electron microscopy of mouse spleen lymphocytes and thymocytes (previously coated with mouse IgG anti-Thy-1 antibody) treated with IgG anti-Fer/SpA/IgG anti-mouse Ig complex and Fer gave better resolution and higher accuracy than previously obtained with IgG anti-HRP/SpA/IgG anti-mouse Ig complex and HRP (Mandache et al., 1980). Surface Thy-1 alloantigen and Fc receptor (charged with human IgG) treated with a mixture of IgG anti-Fer/SpA/IgG anti-Thy-1 and IgG anti-HRP/SpA/IgG anti-human Fab could be simultaneously detected on the thymocyte surface by either light or electron microscopy using Fer and HRP. The concomitant visualization of Thy-1 alloantigen (with Fer) and FcR (with HRP) on mouse thymocyte clearly shows that their distribution is largely independent and that the amount of Thy-1 antigen is greater. These results show that electron microscopy with a mixture of MHA is a useful technique for simultaneous location of two antigenic markers on the cell surface.

Animals↗
PubMed1980

Multivalent hybrid antibody with double specificity as a tool for locating cell surface antigens by electron microscopy.

Multivalent hybrid antibody complexes with dual specificity were prepared by combining rabbit antibody with anti-mouse immunoglobulin (mIg) and anti-peroxidase (HRP) specificity using protein A of Staphylococcus aureus. The presence of two antibody molecules with anti-mIg and anti-HRP specificity in a single molecule of hybrid complex was demonstrated by their abilities to produce hemagglutination with both HRP-coated and mIg-coated sheep red cells, to give a reaction of complete identity with mIg and HRP and to allow mIg bearing lymphocytes to form rosettes with HRP-coated sheep red blood cells. Electron microscopy of mouse lymphocytes and thymocytes (previously coated with mIg anti-Thy-1 antibody) treated with hybrid antibody complex and HRP showed strong and specific staining of the cell membrane of both cell types. The hybrid antibody complex containing anti-HRP antibody is a valuable reagent for determining various antigenic markers on cell membranes by electron microscopy.

Animals↗
PubMed1979

In vivo and in vitro investigations on a fast growing Brenner tumor.

In vivo and in vitro investigations performed on a fast growing Brenner tumor show the following peculiarities of this tumor: 1. wide epithelial islands embedded in connective ovarian stroma, 2. rich proliferation of epithelial cells in organ cultures with the presence of mitotical figures, 3. numerical variations of chromosomes in certain metaphases. All these peculiarities reveal the tumor borderline stage.

Brenner Tumor↗
PubMed1978

I. An ultrastructural investigation on erythrocytes and lymphocytes coated with proteins: use of CrCl3 as an electron-dense marker.

Proteins (human immunoglobulin G and protein A of Staphylococcus aureus) coupled to the surface of erythrocytes (sheep, mice, man and chicken) and to mouse spleen lymphocytes by chromic chloride technique acquire electron-dense properties and may be visualized in electron microscopy. Sheep red blood cells coated with rabbit anti-erythrocyte antibodies and treated with chromic chloride showed continuous electron-opaque labelling of the cell membrane due to chelation of rabbit IgG with chromium atoms.

Animals↗
PubMed1978

II. Ultrastructural differences in attachment patterns of indicator cells to target cells in the rosette-forming process.

A comparison was made of the electron microscopic appearances of rosettes formed between mouse spleen lymphocytes and indicator cells with the ligands exposed on their surfaces either in clusters or in continuity. Sheep red blood cells (SRBC) coated with protein A of Staphylococcus aureus or human IgG by the chromium chloride technique were used as indicator cells with cluster distribution of the ligand. RBC coated with rabbit IgG anti-sheep red blood cells or staphylococci were used as indicator cells with uniform distribution of the ligand. Results show that the appearance of the zones of contact (point attachment or broad zone attachment) between lymphocytes and indicator cells are mainly influenced by the distribution of the specific ligands on the surface of the indicator cells and do not reflect the pattern of distribution of receptors on lymphocytes.

Animals↗
PubMed1978

Effect of cell density on the disappearance of cell surface immunoglobulins.

Mouse macrophages and human peripheral blood lymphocytes exhibiting on the membrane autologous IgG as well as mouse thymocytes coated with human IgG, showed a strong cell concentration dependence of surface IgG disappearance during an incubation at 37 degrees C. Mouse spleen lymphocytes treated with anti-mouse Ig behaved in the same way regarding the disappearance of surface immunoglobulins, while the redistribution of ligands (cap formation) was not dependent on cell concentration.

Animals↗
PubMed1977

Comparative morphological and cytogenetical investigations on human ovarian granulosa cell tumors.

Comparative morphological and cytogenetical investigations of three granulosa cell tumors revealed the existence of two distinct categories which represent two morphocytogenetical stages of tumor progression. The following peculiarities characterized them: 1) In the premalignant stage the microfollicular and macrofollicular patterns with Call-Exner body like structures are prevailing and besides normal diploid metaphases some neardiploid are found. 2) In the malignant stage following the occurence and gradual selection of a neartriploid neoplastic cell type undifferentiated sarcomatous aspects are dominant.

Culture Techniques↗
PubMed1976

Nuclear inclusions and other ultrastructural aspects in the liver of animals treated with n-2-acetylaminofluorene.

In the course of two chronic experiments including the administration of N-2-acetylaminofluorene (N-A-AF) to male Wistar rats, alterations were observed in the fine structure of the nuclei isolated from the liver. After the first 3 to 4 months of ingestion of the carcinogen, the heterochromatin became uniformly distributed throughout the nucleus, with dissociation of the nucleolus-associated heterochromatin. At longer intervals (7 months) evidence was found in the nucleus of various types of inclusions, chiefly granular virus-like bodies. Subsequently, the frequency of inclusions diminished but the liver cell nucleus remained large, with numerous large nucleoli. This suggested the existence of a stage of metabolic activation of the liver cell nucleus in the course of experimental induction of hepatocarcinoma with N-A-AF, giving rise to an increase in the nuclear and nucleolar volume by accumulation of synthesis products and disorders in nucleo-cytoplasmic exchanges.

2-Acetylaminofluorene↗