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Biomedical subjects

F Ramaekers

Publications and source records attributed to F Ramaekers.

At least 73 records · Page 4Linked to original sources
PubMed1983

Oral granular cell lesions. An immunohistochemical study with emphasis on intermediate-sized filaments proteins.

Six cases of oral granular cell lesions were studied with respect to intermediate-sized filaments (IF), peanut lectin binding (PNL) and muramidase activity by means of the peroxidase antiperoxidase technique. The tumours included three granular cell myoblastomas of the tongue (GCM) two cases of congenital gingival granular cell tumour (CGGT) and one granular cell ameloblastoma (GCA). Every tumour studied showed intracytoplasmic PNL binding whereas muramidase was negative in all cases. Vimentin expression was demonstrated in the CGGT and to a lesser extent in the GCM, but was absent in the GCA which was positive for keratin. Desmin and glial fibrillary acidic protein (GFAP) were not present in any of the lesions. These data demonstrate that PNL binding might be considered to be a common feature of granular cells regardless of their histogenesis. Lysosomes are supposed to represent the intracellular binding sites for this marker. Moreover it is shown that histomorphological identity between the granular cells of CGGT and GCA does not signify identity in histogenesis since the former are of mesenchymal derivation while the latter, from their intermediate filament protein types appear to originate from epithelium.

Ameloblastoma↗
PubMed1983

Organization and expression of the vimentin gene.

The primary structure of hamster vimentin has been derived from the nucleotide sequence of the corresponding cDNA. The elucidation of the amino acid sequence allowed the prediction of a model in which two helix domains occur. The N-terminal and C-terminal part have been characterized as nonhelical domains. Moreover the two helices are separated by a third nonhelical region.

Amino Acid Sequence↗
PubMed1983

Demonstration of keratin in human adenocarcinomas.

The occurrence and localization of intermediate-sized filaments in 85 cases of adenocarcinoma have been examined by the indirect immunofluorescence technique as well as by the immunoperoxidase technique. Frozen sections of human tumor tissue were incubated with antibodies to keratin, vimentin, and desmin. In contrast to earlier studies by Schlegel et al, this study demonstrates the presence of keratin in 64 cases of primary adenocarcinoma, including tumors of stomach, colon and rectum, lung, pancreas, bile ducts, ovary and uterus, female breast, and prostate, and in 21 cases of adenocarcinomatous metastases in lymph nodes, thoracic and abdominal wall, omentum, mesentery, testis, liver, and the pelvis. In order to establish the possibility of demonstrating intermediate filament proteins by immunohistochemical techniques in fixed, paraffin-embedded material, the authors tested seven fixation methods. It is concluded from the data that antibodies to intermediate filament proteins can be useful in the differential diagnosis of adenocarcinomas because they can distinguish them from tumors of nonepithelial origin in frozen sections.

Adenocarcinoma↗
PubMed1983

Monoclonal antibody to keratin filaments, specific for glandular epithelia and their tumors. Use in surgical pathology.

A monoclonal antibody (RGE 53) against keratin intermediate filaments was prepared by fusing myeloma cells with splenic lymphocytes from mice immunized with a HeLa cell cytoskeleton preparation and human callus keratins. The antibody, selected for fibrillar staining in HeLa cells and a negative reaction on human skin, was tested on frozen sections from normal and malignant human tissues. RGE 53 specifically recognizes glandular epithelial cells from female breast, digestive, respiratory, and urogenital tracts, endocrine and exocrine tissues, and mesothelial cells. No reaction is found in stratified squamous epithelia or nonepithelial tissues. Furthermore, RGE 53 can distinguish adenocarcinomas and mesotheliomas, which stain positively in the indirect immunofluorescence technique from squamous cell carcinomas and nonepithelial tumors, which are negative for this antibody. RGE 53 may, therefore, be a useful tool for differential diagnosis in surgical pathology, especially in those cases in which anaplastic carcinomas have to be characterized.

Adenocarcinoma↗
PubMed1982

Classification of rat lens crystallins and identification of proteins encoded by rat lens mRNA.

Endogenous rat lens crystallins have been separated by gel filtration into four fractions, alpha, beta H, beta L and gamma-crystallin. Elution patterns of soluble lens proteins from animals of different ages show a relative decrease of beta H and gamma-crystallin during aging. Conversely the relative amounts of alpha and beta L-crystallin are enhanced. The rat crystallin subunits from the four fractions were characterized by one-dimensional and two-dimensional gel electrophoretic techniques. From the results a classification could be derived and a nomenclature for the soluble rat lens proteins is proposed. The products synthesized by rat lens mRNAs in a heterologous cell-free system have also been characterized. Co-electrophoresis of the radioactive products synthesized de novo together with the isolated unlabeled protein fractions on two-dimensional gels shows the relation between primary gene products and their posttranslationally modified derivatives.

Aging↗
PubMed1982

The genes coding for the cytoskeletal proteins actin and vimentin in warm-blooded vertebrates.

Recombinant plasmids were made containing cDNAs synthesized on hamster mRNAs coding for cytoskeletal (beta- or gamma-) actins and for vimentin. Hybridization of the actin probe on restriction digests of one avian and five mammalian DNAs yielded multiple bands; the vimentin probe revealed only one band (accompanied by 2-3 faint bands in some DNAs). The results obtained with the vimentin probe indicate that the corresponding coding sequences: (a) are highly conserved in warm-blooded vertebrates like the actin sequences; (b) have strongly diverged from those coding for other intermediate filament proteins, since hybridization of the vimentin probe does not lead to a diagnostic multiband pattern; and (c) most likely contribute to single gene, in contrast to the sequences coding for other cytoskeletal proteins. Hybridization of the probes on mRNAs from the different sources used showed that the non-coding sequences of both vimentin and actin genes are conserved in length.

Actins↗
PubMed1982

Differential diagnosis of human carcinomas, sarcomas and their metastases using antibodies to intermediate-sized filaments.

Intermediate filaments (IF) are tissue-specific in so far that epithelial, mesenchymal, muscle and neural tissue types can be distinguished by the use of specific antibodies to keratin, vimentin, desmin and neurofilaments or glial filaments respectively. We have examined the possibility of using these sera in the differential diagnosis of human malignant tumors. Using antisera to human skin keratin and bovine lens vimentin we could differentiate between carcinomas (keratin +) and sarcomas (vimentin +). Furthermore, we could show that when cells become malignant and metastasize they retain their original IF and do not develop additional IF systems. We conclude that antibodies to IF proteins are powerful tools in the hands of a pathologist as an additional method to improve identification of tumors and their metastases.

Antibodies, Neoplasm↗
PubMed1980

The role of 7-hydroxymethotrexate during methotrexate anti-cancer therapy.

Plasma concentrations of 7-hydroxymethotrexate were measured in 10 individuals receiving methotrexate, 8 of them per infusion. After the end of infusion, the plasma concentration of formed 7-hydroxymethotrexate fell less rapidly than that of methotrexate. At 24 h after infusion, plasma concentration ratios of 7-hydroxymethotrexate ranged from 30 to 1 (n = 8). The presence of 7-hydroxymethotrexate was shown to influence the transport of methotrexate into Ehrlich ascites tumor cells and human KB cells, cultured in vitro. These findings suggest that monitoring of 7-OHMTX is important in MTX treatment.

Animals↗
PubMed1978

Parallel changes in behaviour and hippocampal monoamine metabolism in rats after administration of ACTH-analogues.

Application of footshock during the acquisition trial of a one-trial passive avoidance test is associated with a rise in the concentration of serotonin in the hippocampi of rats 24 hr after termination of the acquisition trial. Rats subjected to amnesic treatment with carbon dioxide (CO2) immediately after footshock do not show this rise in the hippocampal concentration of serotonin. The ACTH-analogues, ACTH 4-10 and ACTH 4-10 (7D-Phe), alleviate CO2-induced amnesia for the passive avoidance response when administered 1 hr before retrieval test 24 hr after acquisition. These peptides do not have anti-amnesic activity when given before acquistion. Another ACTH-analogue, ACTH 11-24 does not affect amnesia, given before either the acquisition or the retrieval test. The anti-amnesic effect of ACTH 4-10 AND ACTH 4-10 (7D-Phe), was correlated with a rise in the hippocampal serotonin concentration similar to that observed in non-amnesic animals. Pre-acquisition treatment with ACTH 4-10 or administration of ACTH 11-24 did not affect hippocampal serotonin concentrations. Changes in the hippocampal concentrations of noradrenaline, dopamine, tryptophan and tyrosine were not related to the behavioural activity of any of the peptides. It is suggested that alterations in hippocampal serotonin metabolism 24 hr after acquisition of a passive avoidance response are associated with the retrieveability of the passive avoidance response.

Adrenocorticotropic Hormone↗
PubMed1977

Parallel changes in behaviour and hippocampal serotonin metabolism in rats following treatment with desglycinamide lysine vasopressin.

Application of a foot shock during the acquisition trial of a one-trial passive avoidance task is associated with a rise in the concentration of serotonin in the hippocampus 24 h after conclusion of the acquisition trial. Carbon dioxide (CO2) induces amnesia for the passive avoidance response when administered immediately upon termination of the acquisition trial. In rats subjected to CO2 treatment following foot shock the rise in hippocampal serotonin is not observed 24 h later. The vasopressin analogue desglycinamide lysine vasopressin attenuates CO2-induced amnesia for the passive avoidance response when given prior to either the acquisition or the retrieval test (24 h after acquisition). This attenuation of the passive avoidance response is associated with a rise in the hippocampal serotonin concentration similar to the one observed in non-amnesic animals. It is suggested that a correlation exists between changes in hippocampal serotonin metabolism and the retrievability of the passive avoidance response.

Amnesia, Retrograde↗
PubMed1976

Monamines in brain and urine of rats with hereditary hypothalamic diabetes insipidus.

Monoamine levels in brain and urine of homozygous and heterozygous diabetes insipidus (DI) rats (Brattleboro strain) were assessed. Homozygous DI rats had a higher whole brain content of serotonin than their heterozygous littermates. However, when corrected for differences in brain weight, homozygous DI also appeared to have higher brain concentrations of noradrenaline, tyrosine and GABA. The total 24 h excretion of all amines and their precursors was greater in the homozygous than in the heterozygous rats.

Animals↗
PubMedDate not supplied

Chronic hibernating myocardium: interstitial changes.

Chronic left ventricular dysfunctional but viable myocardium of patients with chronic hibernation is characterized by structural changes, which consist of depletion of contractile elements, accumulation of glycogen, nuclear chromatin dispersion, depletion of sarcoplasmic reticulum and mitochondrial shape changes. These alterations are not reminiscent of degeneration but are interpreted as de-differentiation of the cardiomyocytes. The above mentioned changes are accompanied by a marked increase in the interstitial space. The present study describes qualitative and quantitative changes in the cellular and non-cellular compartments of the interstitial space. In chronic hibernating myocardial segments the increased extracellular matrix is filled with large amounts of type I collagen, type III collagen and fibronectin. An increase in the number of vimentin-positive cells (endothelial cells and fibroblasts) compared with normal myocardium is seen throughout the extracellular matrix. The increase in interstitial tissue is considered as one of the main determinants responsible for the lack of immediate recovery of contractile function after restoration of the blood flow to the affected myocardial segments of patients with chronic left ventricular dysfunction.

Actins↗
PubMedDate not supplied

Microfilament assembly during lens cell elongation in vitro.

Bovine epitheloid lens cells can be kept in culture for almost one year. During subculturing a gradual process of cell elongation is observed. Using several techniques, including immunofluorescence with antibodies against actin, electron microscopy, two-dimensional gel electrophoresis, drug treatment and measurement of actin polymerization by DNase I inhibition, it is shown that microfilament assembly parallels the process of cell elongation.

Animals↗