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Biomedical subjects

A Delacourte

Publications and source records attributed to A Delacourte.

At least 163 records · Page 9Linked to original sources
PubMed1986

Alzheimer's disease: Tau proteins, the promoting factors of microtubule assembly, are major components of paired helical filaments.

A rabbit antiserum was raised against paired helical filaments (PHF). This antiserum stains specifically neurofibrillary tangles (NFT) at the light-microscopic level and PHF at the electron-microscopic level in sections of Alzheimer neocortex and hippocampus. We studied the nature of the antigens recognized by this antiserum by immunocytochemistry, immunoblots and immunoadsorption. These approaches showed that the anti-PHF specifically labels a set of low molecular weight 65-50 kDa microtubule-associated proteins, named Tau proteins, which are promoting factors of microtubule assembly. Furthermore, antisera against Tau proteins stained NFT. It is concluded that neurofibrillary tangles are very likely composed of aggregated Tau proteins. This process might be due to an abnormal Tau protein synthesis or to an unknown lesion of certain pyramidal neurons leading to an aggregation of Tau proteins.

Adult↗
PubMed1986

Biochemical and immunological studies of bovine and porcine neurofilament triplet proteins by peptide mapping after cyanogen bromide cleavage.

Peptide mapping of the three bovine and porcine neurofilament protein subunits ("L", "M" and "H") with apparent mol. wts of 70, 160 and 210 kDa were performed with CNBr, leading to the cleavage of methionyl bonds. We have obtained two characteristic large fragments with molecular weights of 85 kDa for the "M" bovine subunit and 135 kDa for the "H" subunit of bovine neurofilament. A comparison of the electrophoretic patterns of CNBr generated polypeptides of "L" subunit from beef and pig showed that they are highly related structures. The peptide mappings of CNBr peptides of "M" and "H" subunits from beef and pig were significantly different. Antibodies were raised against the 85 kDa and 135 kDa CNBr fragments. Immunoblotting results with anti-85 kDa and anti-135 kDa of beef are in favour of large differences of structure between the "M" subunits from pig and beef. The "H" proteins were very similar and they also showed that the C-terminal part of bovine "H" and "M" proteins share common antigenic determinants.

Animals↗
PubMed1986

[Biochemical characterization of an immune serum which specifically marks neurons in neurofibrillary degeneration in Alzheimer's disease].

We have raised an antiserum which is labelling specifically neurofibrillary tangles of Alzheimer's disease. We show here that anti-tangles detects on immunoblots exclusively Tau, a set of proteins that promote microtubule assembly. Conversely, an anti Tau detects histologically Alzheimer tangles. Accordingly, neurofibrillary tangles are very likely composed of aggregated Tau proteins, due to an anomaly of microtubular protein synthesis or to a general suffering of certain pyramidal neurons leading to an elective aggregation of Tau.

Alzheimer Disease↗
PubMed1986

Chemical and pharmacological studies of 2-(amino-methyl)acrylophenones.

The structure-activity relationships of nine products of the acrylophenone family have been studied. In a previous report 2-(4-methyl-1-piperazinylmethyl)acrylophenone was shown to be an antimicrotubular drug. The effects of these drugs on the bovine brain tubulin polymerization were determined by a turbidimetric assay. The median inhibitory concentrations (ID50) ranged from 1.5 X 10(-5) to 5 X 10(-5) mol/l. Their action on the inhibition of 3H-colchicine binding to tubulin was determined by DEAE (diethylaminoethyl)cellulose filter assay. These compounds are weak inhibitors of colchicine binding. Pharmacological studies of these drugs revealed a strong inhibition of the human ADP-induced platelet aggregation. Moreover, they markedly decreased the serum cholesterol, triglycerides and phospholipids levels of rats after injection of Triton WR 1339 (4-(1,1,3,3-tetramethylbutyl)phenol polymer with formaldehyde and oxirane). They inhibited Candida albicans, Penicillium notatum and Aspergillus versicolor growth. Thus, these nine compounds possess interesting pharmacological properties which are very likely to be related to the acrylic moiety of the molecules.

Acrylates↗
PubMed1985

Anti-PHF antibodies: an immunohistochemical marker of the lesions of the Alzheimer's disease. Characterization and comparison with Bodian's silver impregnation.

An immune serum raised against paired helical filaments (PHF) was able to stain senils plaques (SP) and neurofibrillary tangles (NFT) specifically, the two characteristic lesions of the dementia of Alzheimer-type. This polyclonal antibody against PHF was characterized by immunochemistry and also compared with the classical Bodian silver staining. NFT and SP were observed where they were expected: in the fronto-temporal neo-cortex and hippocampus of Alzheimer-type patients, and also in hippocampus of non-demented elderly subjects. The pattern of SP visualized by the two methods was identical whereas NFT were not detected specifically by silver salts, specially in the nervous tissue where NFT were in discrete quantities. Since the preparation of the antigen is very easy and the resulting antibodies are specific, we conclude that this technique will be of considerable interest for routine neuropathological diagnosis. Finally, the properties of our anti-PHF antibody are compared with those reported in the literature. This antibody will probably be a good tool for the identification of the chemical nature of PHF components.

Adult↗
PubMed1985

Comparative studies of the neurofilament triplet protein peptide mapping by chemical cleavage.

Peptide mapping of the three neurofilament protein subunits with apparent mol. weights of 210 kDa, 160 kDa and 70 kDa was performed with two different reagents: CNBr, BNPS-Skatole leading to the cleavage of methionyl and tryptophanyl bonds respectively. With BrCN we obtained two large fragments resistant to the cleavage, with mol. wts of 85 kDa for the 160 kDa and 135 kDa for the 210 kDa neurofilament proteins respectively. These fragments were located on the C-terminal part of the proteins (the tails) and correspond to specific regions responsible for their physiological identity. On the other hand, the cleavage with BNPS-Skatole at the tryptophanyl bonds gave similar patterns. The 210 kDa and 160 kDa neurofilament proteins gave a doublet of high mol. wt resistant to the cleavage, corresponding very likely to the C-terminal part and 4 fragments of mol. wt between 30 and 40 kDa corresponding to the N-terminal part. The neurofilament triplet share a common 30.5 kDa fragment located on the N-terminal part. From these peptide mapping studies, we conclude that the two neurofilament subunit proteins with mol. wts of 160 kDa and 210 kDa are different but related structures and that the CNBr characterized cleavage fragments of mol. wt 85,000 and 135 kDa are suitable polypeptides for sequence and immunological studies of the C-terminal part of these proteins.

Animals↗
PubMed1985

Pharmacological study of nine antimicrotubular drugs with acrylophenone structure on Triton WR 1339-induced hyperlipidemia in rats.

Nine (amino-methyl)-2 acrylophenone derivatives having in vitro antimicrotubular activities very similar to those of colchicine are tested on Triton WR 1339-induced hyperlipidemia in rats. By producing a disorganization of the microtubular system, these drugs reduce the lipoprotein secretory process from hepatocytes, and more particularly the triglyceride-rich VLDL secretory process, such that the serum triglyceride, cholesterol and phospholipid levels are decreased. On the other hand, HDL-cholesterol and HDL-phospholipids are increased in a significant manner. Other studies show that serum apoprotein B levels are decreased while serum apoprotein A1 levels are increased. These results are interesting since atherogenous risk is now known to be dyslipemia-related, and is not the same according to the fact that lipids are bound to one or another lipoprotein. Among the four most effective compounds (5,7,8 and 9) three of them possess a methoxy group on the aromatic ring, which seems to distinguish that series from the other two.

Animals↗
PubMed1984

Accessibility and cross-linking of native neurofilaments to chemical reagents.

Native neurofilaments were submitted to cross-linking reactions with bifunctional reagents (DMA, DMS and DSS) and to chemical reactions with sterically bulky reagents such as EEDQ and DTAF , as well as a glutaraldehyde-activated gel. The 160K and 70K neurofilament proteins reacted slightly more than the 210K neurofilament protein with DMS and DSS. The accessibility of the three neurofilaments to the other chemical reagents was identical. These results were unexpected since neurofilament antibodies seem to react preferentially with 210K protein which is at the periphery of the filament, whereas the 70K protein, which is the backbone of the filament, is probably buried inside the filament. In the same way, it has been shown that the side of the 210K proteins are probably able to cross link the neurofilaments with non covalent and covalent bridges. Using different cross link reagents, we did not observe a characteristic reactivity of the 210K protein towards the different chemicals. We conclude that the three neurofilament proteins are equally exposed to the different sterically bulky reagent and that part of the polypeptide chain of the 70K and the 160K proteins are located at the outside of the filament.

Animals↗
PubMed1984

2-(4-methyl-1-piperazinylmethyl) acrylophenone dihydrochloride: a new antimicrotubular drug.

With the relation between chemical structure and pharmacological activity as a guide, we have been for some time synthetizing a wide range of beta-amino-ketone derivatives. One of them, 2-(4-methyl-1-piperazinylmethyl) acrylophenone, MPMAP, possesses antimicrotubular activities. This product inhibits 50% of the microtubule polymerization at a 3.10(-5) M concentration. It does not prevent tubulin paracrystal formation induced by vinblastine, and binding experiments reveal that this product is a weak inhibitor of colchicine binding. The structure of this compound is different from the other antimicrotubular agents and has the advantage of being far less complex, highly soluble and easy to synthesize. Thus, this product and related compounds should be a new tool for the study of antimicrotubular activities and tubulin assembly.

Animals↗
PubMed1984

Preliminary note: effect of microtubule inhibitors with acrylophenone structure on Triton WR 1339 induced hyperlipidemia in rats.

Acrylophenone derivatives having in vitro antimicrotubular activity very similar to that of Colchicine were tested on Triton WR 1339 induced hyperlipidemia in rats. By inducing a disorganization of the microtubular system these compounds decreased the movement of very low density lipoproteins (VLDL) to the extracellular space and consequently decreased hypertriglyceridemia. On the other hand, contrary to Colchicine, these derivatives decreased cholesterolemia more significantly and this could be explained by a second action mechanism.

Acrylates↗
PubMed1984

Antimicrotubular effects of ethacrynic acid.

Ethacrynic acid is a well known diuretic drug. We present here evidence that this compound is also an antimicrotubular agent which inhibits the brain tubulin polymerization and can displace 3H colchicine from its binding site. Since 2-mercaptoethanol reversibly inhibits the anti-microtubular properties, we conclude that ethacrynic acid binds covalently to brain tubulin through a cysteine near the colchicine site.

Animals↗
PubMed1982

Characterization of mammalian neurofilament subunits by circular dichroism.

Critical steps in the disassembly and reassembly of neurofilaments, the intermediate filaments of neurons, have been investigated. Bovine neurofilament subunits (Mr 210 000, 160 000 and 70 000) were purified by urea-polyacrylamide gel electrophoresis and renatured by dialysis against several non-denaturing buffers. The quality of the protein renaturation was measured by circular dichroism. The spectra of renatured neurofilament subunits were interpreted in terms of secondary structure and this showed that the solubilization of proteins in guanidine-HCl buffers is more suitable than in urea buffer for a good recovery of a filamentous structure. Furthermore, it is shown that (i) the three neurofilament subunits exhibit specific CD spectra, with shapes reminiscent of those obtained for the alpha/beta class of proteins and that (ii) there is good correlation between CD spectra, the state of renaturation and the ability of the proteins to assemble into filamentous structures. We conclude that CD studies of neurofilament proteins should help in understanding the numerous variables affecting the disassembly and reassembly of neurofilaments.

Animals↗
PubMed1980

Study of the 10-nm-filament fraction isolated during the standard microtubule preparation.

The cold non-depolymerizable fractions obtained during the standard procedure for the isolation of microtubules from ox brain stem-cerebral hemispheres and spinal cord have been studied. The cerebral-hemisphere preparation was composed of 10-nm filaments but also contained large amounts of membranes. The polypeptide content included tubulin, microtubule-associated proteins and minor proteins corresponding to the neurofilament triplet of proteins of mol.wt. 210 000, 160 000 and 70 000 respectively. The brain-stem preparation contained more 10-nm filaments than membranes. The polypeptide content consisted of the neurofilament triplet (35%), tubulin (30%) and minor proteins. In contrast, the spinal-cord preparation was mainly composed of 10-nm filaments, free of membranes and containing essentially the neurofilament protein triplet (64%). These filaments appeared very similar to the peripheral-nervous-system neurofilaments described by several authors. Since the best neurofilament from the central nervous system often contained less than 15% of the neurofilament protein triplet, our spinal-cord preparation is an improvement on the usual neurofilament preparation. This simple and rapid method gave large amounts of 10-nm filaments (100 mg per 100 g of spinal cord) characterized by the absence of membranous material, a low content of tubulin and the 50 000-mol.wt.-protein component, and a high content of neurofilament peptides. Thus, the presence of tubulin in 10-nm filament preparations seems to be related to the contaminant membranous material and not to be linked to the interaction in vitro of tubulin or microtubules with neurofilaments, as has been suggested previously.

Animals↗
PubMed1979

The polypeptides of isolated brain 10nm filaments and their association with polymerized tubulin.

Brain 10 nm filaments were isolated from bovine, rabbit and rat brains by a modification of an existing procedure. The overall polypeptide composition of these preparations was similar to that previously reported for brain neurofilaments. In addition to the major polypeptide component, which has mol. wt. approx. 50 000, three other polypeptides with chain mol. wts. approx. 210 000, 155 000 and 70 000, which correspond to peripheral-nerve neurofilament polypeptides, were consistently found to be present. The mol. wt.-50 000 species was found to be heterogeneous and may contain a component derived from the mol. wt. 70 000 polypeptide. The three higher-molecular-weight polypeptides did not appear to be obviously homologous or to be homologous with myosin or Myxicola neurofilament polypeptides. These same three higher-molecular-weight components were shown to be identical with the polypeptides probably responsible for the 10 nm filaments formed during the early cycles of the tubulin-purification protocol.

Animals↗