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Biomedical subjects

G Citro

Publications and source records attributed to G Citro.

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

Characterisation of a human glioblastoma cell line (LI) expressing hypothalamic and pituitary hormones.

The human glioblastoma cell line LI showed morphological features typical of its neuroectodermal origin. Cells were positive by immunofluorescence to GFAP, MHC class II, and L1 determinants. Cytogenetic analysis showed the presence of a modal chromosome number of 63, ranging from 58 to 69 chromosomes (DNA index was 1.6). Northern blot analysis demonstrated the presence of mRNA transcripts specific for transglutaminase C (type II or "tissue"), growth-hormone releasing-hormone (GHRH), insulin-like growth factor II (IGF-II), and proopiomelanocortin (POMC). The GHRH mRNA was present in two different sizes, one similar to the normal hypothalamic species of 0.75 kb, whilst the second species was a large transcript of approximately 10 kb size. Treatment with 5 microM retinoic acid or 5 mM alpha-difluoromethylornithine for 5 days sharply reduced the growth rate and also induced modulation of the ultrastructure and antigenic profile. This cell line may be useful to study glial differentiation and the relationship of GHRH, IGF-II and POMC expression with differentiation in neuroectodermal tumours.

Blotting, Northern↗
PubMed1992

Expression of glutathione transferase pi in benign and malignant lesions of the melanocyte lineage.

Intrinsic and acquired resistance to chemotherapeutic agents represents the major clinical obstacle in the control of most tumours. In vitro studies have established that multiple mechanisms, including changes in drug uptake and efflux and in detoxifying enzymes, are responsible for drug resistance. Among the latter, glutathione S transferases (GST) have been recognized to play a relevant role. In the present study we have evaluated GST pi immunohistochemically as well as enzymatically in benign and malignant primary and metastatic lesions of the melanocyte lineage. A parallel analysis of the multiple drug resistance (MDRI) gene product was performed in a representative number of specimens. Results of this study demonstrate that while GST pi is constitutively expressed by the melanocyte lineage, independently from the transformed stage, MDRI p-glycoprotein is detected with a significantly lower frequency. These findings clearly indicate that GST pi represents the major detoxifying metabolic pathway of the melanocyte lineage and may be responsible for the high degree of inherent resistance of malignant melanoma to available cytostatic treatments.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1991

Glucose utilization by tumor cells: a post-translational modification of mitochondrial hexokinase may play a regulatory role.

In Northern blot analysis of a series of tumor cell lines a single hexokinase mRNA species of 4.3 Kb was detected. Detailed examination of one such line, the rat AS-30D hepatoma, revealed that two mitochondrial species of hexokinase are present with a molecular mass of 115 and 107 KDa. The smaller of the two species is 4-fold more active than the larger. Only the larger, less active species is detected in the well differentiated H-35 rat hepatoma cell line which exhibits a lower glucose catabolic rate. These results suggest that a post-translational proteolytic event may play a central role in regulating the glucose utilization capacity of tumor cells by modulating the relative levels of high and low activity forms of hexokinase.

Animals↗
PubMed1991

Specific recognition of human pi glutathione transferase by an antipeptide antibody.

Antibodies were raised in a rabbit by using a 12-residue synthetic peptide, corresponding to fragment 2-13 of rat placental glutathione S-transferase, as the immunogen. The antiserum appeared to react with the fragment as well as with the corresponding human enzyme (GST-pi), which shares with the rat transferase a 92% sequence homology at the N terminus. In addition, the binding of the antibody to the protein was completely inhibited by small amounts of peptide. The enzymatic activity of glutathione transferase was not affected by the antibody. This might indicate that the N-terminal fragment is not involved in the catalytic activity of the enzyme. This antibody of predetermined specificity might thus find a useful application for the detection and approximate quantitation of this marker in human preneoplastic lesions.

Amino Acid Sequence↗
PubMed1991

Brief communication. on the problem of immunological detection of antigens in skeletal remains.

A detailed investigation with affinity-chromatography-purified fractions of antihemoglobin serum from rabbit shows that the hemoglobin content of human bones dating back 15 to 3,000 years may be very small. Some of the previous results (Ascenzi et al., 1985) indicating a high hemoglobin titer were +vitiated because of an unexpected cross-reactivity of bone extracts with the hemoglobin-unreactive fraction of the antiserum.

Animals↗
PubMed1991

Escherichia coli DNA-binding protein H-NS is localized in the nucleoid.

Electron microscope localization of the 15.4-kDa DNA-binding protein H-NS was carried out in Escherichia coli cells subjected to cryosubstitution followed by immuno-labelling with the protein A/gold technique. Three types of E. coli cells were used: (1) "normal" cells growing exponentially at 37 degrees C; (2) "cold-shocked" cells two hours after the shift from 37 degrees C to 10 degrees C; and (3) cells in which an expression vector had been induced to overproduce H-NS. The results clearly indicate that in all 3 cases, the vast majority of the molecules reacting with anti-H-NS antibodies are localized within the nucleoid and at the border between the nucleoid and the ribosome-rich cytoplasm, which supports the premise that H-NS is implicated in the condensation of the nucleoid.

Bacterial Proteins↗
PubMed1991

Immunoquantitation of cytochrome C in cardiac perfusate.

An indirect three step ELISA has been assessed in order to detect the possible release of cytochrome c, a mitochondrial protein, from isolated and perfused guinea-pig heart. The ELISA described in this study is sufficiently sensitive and accurate to measure extracellular cytochrome c.

Animals↗
PubMed1990

Biochemical and immunological studies of deglycosylated Rhus vernicifera laccase.

Rhus vernicifera laccase (Japanese) was deglycosylated by treating it with exo- and endoglycosidases. In absence of unfolding agents deglycosylation does not exceed 32% while in denaturating conditions only 10% of saccharides are not digested. In the former case specific activity seems to be directly related to the amount of the residual carbohydrates. After deglycosylation in denaturing conditions the modified enzyme exhibits an electrophoretic component of about 60-65 Kd. A stabilizing effect of saccharide moiety on the catalytic site of native laccase was demonstrated. Antiserum raised against the enzyme recognized native Japanese, Vietnamese as well as deglycosylated laccase indicating that the two isoforms are immunologically similar.

Antigen-Antibody Complex↗
PubMed1989

Production of antibodies against the coenzyme pyrrolequinoline quinone.

Polyclonal antibodies against pyrrolequinoline quinone have been elicited in rabbits. These antibodies react with free and protein-bound pyrrolequinoline quinone. In particular they react with native and denatured lentil seedling amine oxidase as detected by dot-blot and ELISA assays. The presence of 1 mol pyrrolequinoline quinone per mol of enzyme was determined by the last method.

Amine Oxidase (Copper-Containing)↗
PubMed1988

Cellular localization of bovine pancreatic trypsin inhibitor and related molecular forms in bovine lung.

In addition to bovine pancreatic trypsin inhibitor (BPTI), three BPTI-related molecular forms (isoinhibitors I, II and III) were isolated from bovine lung by affinity chromatography on immobilized trypsin and subsequently purified by Fast Protein Liquid Chromatography. These inhibitors are identical to the isoinhibitors previously isolated from bovine spleen. Their localization in bovine lung was studied by immunohistochemical techniques, using two different immunoglobulin preparations, selectively recognizing BPTI or the other molecular forms. BPTI-related immunoreactivity was found to be restricted to isolated cells, often identified as mast cells by Toluidine Blue staining. In contrast, isoinhibitor-related immunoreactivity, which also occurs in the mast cells, is present in a number of other cell types. These types include: (i) the smooth muscle cells of different calibre vessels, (ii) the ciliated cells of the bronchial epithelium and the related mucus, and (iii) many cells at alveolar level. Comparison of these data with previous results obtained for bovine spleen suggest multiple physiological roles for these inhibitors.

Animals↗
PubMed1988

Production and characterization of monoclonal antibodies against DNA single ring diamines adducts.

The synthetic conjugate of the genotoxic compound 2,4 diaminotoluene (2,4 DAT) with gelatin (2,4 DAT-GEL) was employed to elicit specific antibodies directed against a restricted class of aromatic diamines. Using this immunogen, mouse monoclonal antibodies (MAbs) have been produced. These MAbs have been characterized and used in ELISA to detect 2,4 DAT covalently linked to biopolymers. The MAbs could bind to different synthetic 2,4 DAT-biopolymer adducts as well as to DNA from rats treated in vivo with the aromatic diamine, but they did not react with gelatin or biopolymers alone. The use of these MAbs has been investigated in order to develop a highly sensitive test to detect adducts of this genotoxic compound with nuclear DNA.

Animals↗
PubMed1987

Vascular localization of bovine pancreatic trypsin-inhibitor-related molecular forms in bovine spleen.

Bovine spleen proteic inhibitors of serine proteases, belonging to the bovine pancreatic trypsin inhibitor (BPTI or aprotinin) family, have been localized, using immunocytochemical techniques, in the smooth muscle cells of some bovine spleen blood vessels. This vascular localization also occurs in a variety of bovine organs and differs from that of BPTI itself which is found exclusively in bovine mast cells, in agreement with previous reports. These data would be in favour of a possible involvement of one or more BPTI-type inhibitors in vascular processes by acting at the level of the smooth muscle cells, the tissue responsible for vasodilation/vasoconstriction events.

Animals↗
PubMed1987

Kunitz-type inhibitors in human serum. Identification and characterization.

Human serum contains small amounts (approximately 0.1 mg/liter) of two protein protease inhibitors of low molecular weight (approximately 6500) and basic isoelectric point (Kunitz-type). They were purified by affinity chromatography on immobilized trypsin and ion-exchange chromatography in the fast protein liquid chromatography system. Their chemical, immunochemical, and functional properties indicate that the purified inhibitors are highly homologous with the basic pancreatic trypsin inhibitor which is widely distributed in bovids and caprids. Their inhibitory activity toward serine proteases such as plasmin and kallikrein suggests a possible regulatory role in blood clotting and fibrinolysis.

Humans↗
PubMed1985

Immunological detection of hemoglobin in bones of ancient Roman times and of Iron and Eneolithic Ages.

Using an immunological method (immunoblot), we have established that hemoglobin (or hemoglobin fragments) can be quantitatively determined in old and ancient bones, some of them dating back 4500 years. It is shown that the total recovery decreases with time, but it is still effective in the older specimens. Thus, the immunological assay may prove useful to solve problems relevant to paleontology and paleopathology.

Antibodies, Anti-Idiotypic↗
PubMed1985

Characterization of three new Kunitz-type inhibitors from bovine spleen: preparation of specific antibodies.

Antibodies to bovine spleen inhibitors I, II and III were elicited and their effect on the antiproteolytic activity of these Kunitz type inhibitors was tested. The immunoglobulins contain antibodies common to the four inhibitors in agreement with the great structural similarity of these antigens. Specific antibodies, which only react with the related inhibitor, were also isolated with the aim of localizing and quantifying these inhibitors "in vivo".

Animals↗
PubMed1984

Immunochemical studies on the Kunitz type inhibitors from bovine spleen.

Specific immunoglobulins for bovine spleen inhibitor IV, which is identical to the basic pancreatic trypsin inhibitor (Kunitz inhibitor) from bovine lung, were purified from the serum of immunized rabbits. Immunological and immunochemical experiments have shown that the four inhibitors previously isolated from bovine spleen are cross-reacting antigens with the anti-inhibitor IV - antiserum; however, part of the antibodies are precipitated by inhibitors I, II and III, whereas the remaining ones are only specific for the antigenic determinants present on the inhibitor IV molecule.

Animals↗