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Biomedical subjects

F Michel

Publications and source records attributed to F Michel.

At least 217 records · Page 12Linked to original sources
PubMed1987

Effect of chronic treatment with a purified flavonoid fraction on inflammatory granuloma in the rat. Study of prostaglandin E2 and F2 alpha and thromboxane B2 release and histological changes.

S-5682 (Daflon-500 mg), a purified flavonoid fraction, consisting of 90% diosmin (a flavone derivative) and 10% hesperidin (a flavanone derivative), was administered to rats by intubation in the daily dose of 100 mg/d. 15 days after the start of treatment, polyurethane sponges were implanted in the subcutaneous connective tissue in the dorsolumbar region under rapid ether anaesthesia. Similar fragments of sponge were implanted in a group of control animals who received the vehicle (saccharose syrup) only, also by the oral route. The rats were sacrificed in fractions of 7 animals drawn from each of the two groups (control and treated) after 4, 8, 16 and 30 days (only 5 animals from each group on day 30) after implantation of the polyurethane sponges. The granulomas formed were removed, weighed and their prostaglandin (PG)E2, PGF2 alpha and thromboxane (Tx)B2 contents were determined. In addition a full cell count (polymorphs, lymphocytes, macrophages, plasmocytes and giant cells) was performed and the animals were histologically examined. The results show that treatment of the animals with S-5682 had the following effects: 1. A significant fall in the mean weight of the granulomas formed after 4 and 8 days was observed, reflecting inhibition of oedema formation during the early phase of the inflammatory reaction. 2. The synthesis of PGE2 (78.5% inhibition on day 4) and PGF2 alpha (45.2% on day 16) was inhibited. 3. There was very early inhibition of TxB2 synthesis (59.5% inhibition on day 4). 4. A later reduction in cell migration towards the inflammatory focus occurred which was statistically significant on day 16 (49.6% reduction in the total number of migrant cells). 5. Multiple histological aspects of the acute inflammatory reaction (diapedesis of polymorphs, lymphocytes, histiocytes and macrophages) and features of the chronic inflammatory reaction (newly formed microvascularisation of the granuloma tissue, perivascular oedema, presence of collagen fibres) were improved.

Animals↗
PubMed1986

Mitochondrial introns as mobile genetic elements: the role of intron-encoded proteins.

Introns of organelle genes share distinctive RNA secondary structures that allow their classification into two known families. These structures are believed to play an essential role in splicing, and members of both structural classes have recently been shown to perform self-splicing reactions in vitro. In lower eukaryotes, many structured introns also contain long internal open reading frames (ORFs), which are able to code for hydrophilic proteins. Several properties of self-splicing structured introns suggest that they resemble mobile genetic elements, even though no actual transposition event involving these introns has yet been found. We report here on the characterization of two intron-encoded proteins that strongly support this attractive idea. First, we show that the class I intron of the 21S ribosomal RNA (rRNA) gene of Saccharomyces cerevisiae omega+ strains (rl intron) encodes a specific transposase. This protein has been partially purified from Escherichia coli cells that overexpress it from an artificial universal code equivalent to the rl intronic ORF. The omega transposase shows a double-strand endonuclease activity in vitro. This activity creates a 4-bp staggered cut with 3' OH overhangs within a specific sequence of the 21S rRNA gene of omega- strains. It is precisely within this sequence that the rl intron inserts by a duplicative transposition. Second, we report on the synthesis, in E. coli, of a putative reverse transcriptase encoded by the class II intron of the cytochrome b gene of Schizosaccharomyces pombe. This synthesis was obtained from E. coli expression vectors, using the class II intronic ORF linked to an artificial initiator sequence. As further support of the idea that structured introns are mobile, we show, from a systematic screening of introns in various yeast species, that the rl intron has transposed into the ATPase subunit 9 gene of Kluyveromyces fragilis. Structural features observed at the new intron homing site may be relevant to the transposition event.

Adenosine Triphosphatases↗
PubMed1986

Study of the local graft versus host reaction in the rat. I. Evidences for a donor-related "rat effect".

The local graft versus host reaction (GVHR) observed in the hybrid F1 LBN rat was chosen to evaluate the immunologic effect induced by allogeneic transfusion of Brown Norway blood to the Lewis rat. Study of the kinetics of this GVHR with immunized as well as with nonimmunized cells shows an "individual rat effect" which is shown by a variability of the popliteal lymph node weight from one recipient to another. When spleen cells from different Lewis donors are pooled this effect disappears which indicates that it is related to the donor's rather than to the F1 recipient's cells. To even out variation between individual donors, cells from a number of donors should be pooled to allow better interpretation of experimental protocols using this GVHR.

Animals↗
PubMed1986

Listening with one or two hemispheres: verbal dichotic testing after intracarotid barbiturate injection.

A verbal dichotic test was given to 16 patients during right or left hemisphere narcosis induced by intracarotid barbiturate injection (Wada's procedure). During right hemisphere narcosis patients did not repeat left ear words. This demonstrates an intrahemispheric competition within the left hemisphere at the detriment of left ipsilateral ear words. After left dominant hemisphere narcosis, when aphasia had apparently disappeared, patients temporarily did not repeat right ear words. This suggests that, during this critical time period, two competitive processes took place. First the right hemisphere selected the left ear words by an intrahemispheric competition. Second it imposed them on the recovering left hemisphere at the detriment of right ear words, because of an interhemispheric competition.

Auditory Pathways↗
PubMed1986

Primary nonseminomatous germ cell tumor of the prostate.

We describe a case of a primary nonseminomatous germ cell prostatic tumor and discuss the problem of extragonadal germ cell tumors. Prognosis, staging and management of these tumors are similar to that of metastatic primary testicular germ cell tumors.

Adult↗
PubMed1986

[Endomyocardial biopsy in the monitoring of treatment with anthracyclines. Value of the assay of lactate dehydrogenase and its isoenzymes].

Determination of intramyocardial lactate dehydrogenase (LDH) and its isoenzymes (LDH 1 to 5) has been conducted on biopsy material obtained from the right ventricle in 18 patients who had received the theoretical maximal dose of anthracyclines. Total LDH activity, expressed in mU/mg of myocardial protein is higher (852.61 +/- 87.98) than in subjects with good left ventricular function (334 +/- 208), p less than 0.02. The activity of LDH 1 is decreased in the treated group, whereas that of LDH 3,4 and 5 is raised: LDH 1 = 41.95 +/- 7.25 per cent instead of 47.76 +/- 7.93 per cent (p less than 0.03); LDH 3 = 15.34 +/- 5.09 per cent instead of 9.18 +/- 4.56 per cent (p less than 0.05). The H/M ratio (H = fractions of heart isoenzymes; M = fractions of muscle isoenzymes of LDH) is decreased in the treated group: H/M = 4.06 +/- 1.13 instead of 5.30 +/- 1.80 (p less than 0.01). When the histological lesions are minimal (stage 1 or 1.5 of Billingham), the H/M ratio is not altered: 4.92 +/- 1.02. When the lesions attain or exceed stage 2, the H/M ratio is significantly decreased: 3.74 +/- 0.82. These results, which indicate an increase in anaerobic metabolism, add quantitative information to the histological study.

Adolescent↗
PubMed1985

The chloroplast ribosomal intron of Chlamydomonas reinhardii codes for a polypeptide related to mitochondrial maturases.

The sequences of the 888bp chloroplast ribosomal intron and of the flanking 23S rRNA gene regions of Chlamydomonasreinhardii have been established. The intron can be folded with a secondary structure which is typical of group I introns of fungal mitochondrial genes. It contains a 489bp open reading frame encoding a potential polypeptide that is related to mitochondrial maturases.

Amino Acid Sequence↗
PubMed1985

Analysis of class I introns in a mitochondrial plasmid associated with senescence of Podospora anserina reveals extraordinary resemblance to the Tetrahymena ribosomal intron.

Recently, the nucleotide sequences for three "mitochondrial plasmids" associated with senescence of Podospora anserina were determined (Cummings et al. 1985). One of these sequences, corresponding to the plasmid termed epsilon senDNA, contains three class I introns, all within a protein coding sequence equivalent to the mammalian "URF1" gene. Here, we present primary and secondary structure analyses for two of these introns as well as a partial analysis for the third, which extends beyond the DNA sequence determined. With regard to both primary and secondary structure, the closest known relative of intron 1 is the self-splicing intron in the large ribosomal RNA gene of Tetrahymena. One secondary structure domain at the periphery of intron 1 and Tetrahymena models is also present in intron 2. The latter intron is the longest known class I member and contains remnants of two protein-coding sequences, one of which is split by the other. Evolutionary processes that might be responsible for the unusual structure of introns 1 and 2 are discussed.

Animals↗
PubMed1985

Mechanism of enhancing effect of irradiation on production of IL-2.

In order to explain the mechanism of enhancing effect of irradiation on IL-2 production, assumption that radio-induced free radicals could act as a signal for mitogenesis and/or increase lipid peroxidation of T lymphocyte membrane phospholipids was made. Thus, production of metabolites of the lipoxygenase pathway in the arachidonic acid (AA) cascade, known to increase T cell proliferation and lymphokine production could be enhanced by irradiation. We have shown that (1) hydroxyl radical scavenger (DMSO) abolished IL-2 production, (2) inhibitor of the lipoxygenase pathway (NDGA) strongly decreased IL-2 production, (3) thin layer chromatography demonstrated a polar metabolite(s) of AA in increasing amounts according to the following order: non-irradiated resting cells, non-irradiated stimulated cells, irradiated resting cells, and irradiated stimulated cells. Investigations are in progress to identify this metabolite.

Arachidonic Acid↗