Biomedical subjects

P Nadeau

Publications and source records attributed to P Nadeau.

35 records · Page 2Linked to original sources

PubMed1983

Histone synthesis by lymphocytes in G0 and G1.

Peripheral blood lymphocytes are a naturally occurring population of G0 cells which can be activated in vitro to grow and divide. Upon activation with phytohemagglutinin (PHA), they enter G1 and, after a 24-h lag, begin DNA replication (S phase). Using radioisotope labeling and gel electrophoresis of acid-soluble chromatin proteins, we investigated histone synthesis in G0, G1, and S phase cultures of human and pig lymphocytes. In G0 and G1 cultures, which have less than 0.1% S phase cells, all five histones are synthesized and are incorporated into chromatin in equimolar amounts. In G0 lymphocytes histone synthesis accounts for at least 6% of nuclear protein radioactivity, and the rate of synthesis is about 2-3% of that of S phase lymphocytes. In contrast to histone synthesis by S phase cultures, G0 and G1 histone synthesis was completely resistant to treatment with hydroxyurea.

Animals↗

PubMed1982

Changes in protein and RNA during asexual differentiation of Physarum polycephalum.

Some of the events during the growth and asexual differentiation of Physarum polycephalum amoebae are described. Encysted amoebae contain low levels of protein and RNA. When these cells are mixed with bacteria and inoculated onto agar plates, there is an increase in cellular RNA content followed by an increase in protein content. The cellular RNA and protein contents of all strains tested decrease during the subsequent cell divisions. In nondifferentiating cells (strain Cl at 30 degrees C and strain LU648), RNA and protein contents continue to decrease, and the cell eventually encyst. In the asexually differentiating strain Cl grown at 26 degrees C, the cellular RNA and protein contents stop decreasing and begin to increase when the first amoebae become committed to form plasmodia. At early stages of differentiation a new 36,000 molecular weight polypeptide appears. In fully formed plasmodia another polypeptide of 38,000 molecular is observed. These two plasmodial-specific polypeptides are among the most abundant plasmodial proteins.

Cell Division↗

PubMed1982

Isolation and characterization of histones and other acid-soluble chromosomal proteins from Physarum polycephalum.

Chromosomal basic proteins were isolated from amoebal and plasmodial stages of the acellular slime mold Physarum polycephalum. Polyacrylamide electrophoresis on high resolution acid-urea gels separated the five histone fractions in the sequence H1, H2A, H2B, H3, and H4. Under these electrophoretic conditions Physarum histones migrated more like plant (rye) than animal (calf) histones. Furthermore, Physarum histones H1, H2A, and H2B have higher molecular weights on sodium dodecyl sulfate (SDS) gels than the corresponding calf fractions. No differences were detected between amoebal and plasmodial histones on either acid-urea or SDS-polyacrylamide gel electrophoresis. Amoebal basic proteins were fractionated by exclusion chromatography. The five histone fractions plus another major acid-soluble chromosomal protein (AS) were isolated. The Physarum core histones had amino acid compositions more closely resembling those of the calf core histones than of rye, yeast, or Dictyostelium. Although generally similar in composition to the plant and animal H1 histones, the Physarum H1 had a lower lysine content. The AS protein was extracted with 5% perchloric acid or 0.5 M NaCl, migrated between histones H3 and H4 on acid-urea polyacrylamide gels, and had an apparent molecular weight of 15 900 on SDS gels. It may be related to a protein migrating near H1. Both somewhat resembled the high mobility group proteins in amino acid composition.

Amino Acids↗

PubMed1981

Popliteal venous aneurysm: a source of pulmonary embolism.

Explore the source record for details and available documents.

Aged↗

PubMed1980

Application of differential spectra in the ultraviolet-visible region to study the formation of amphotericin B-sterol complexes.

The extent of complex formation between the polyene antibiotic, amphotericin B, and cholesterol or ergosterol was investigated and a method for a quantitative measurement of the complex formation was developed. The effect of experimental conditions on the magnitude of the amphotericin B-sterol interaction and on the selectivity of this interaction showed that there was only a narrow range of solvent composition in which the differential selectivity of amphotericin B towards these two sterols could be observed.

Amphotericin B↗

PubMed1979

Lidocaine plasma concentrations during and after endoscopic procedures.

Plasma lidocaine concentrations were intermittently measured in 8 upper gastrointestinal endoscopy and 12 bronchoscopy patients. The highest individual concentration was 0.98 microgram/ml in the upper gastrointestinal endoscopy patients and 3.79 microgram/ml in the bronchoscopy patients. Highest concentrations were reached at 15 minutes in the gastrointestinal endoscopy patients and at 30 or 60 minutes in the bronchoscopy patients. Thus, since lidocaine does not produce toxic effects at concentrations inferior to 6 microgram/ml, doses of this topical anaesthetic up to 16 mg/kg can be safely given during endoscopic procedures to patients with normal hepatic and cardiovascular functions. However, patients with liver metastases should be considered at high risk even if their liver function tests are normal. Patients at high risk of developing lidocaine toxicity should receive lower doses and be closely watched for at least 60 minutes after the end of the procedure.

Anesthetics, Local↗

PubMed1978

Effect of inhibition of DNA synthesis on histone synthesis and deposition.

We have reinvestigated the degree of coupling between DNA and histone synthesis in mammalian cells. In at least one cell line (HTC cells), the coupling is not nearly as tight as had previously been inferred from experiments with HeLa cells. The site of deposition of such histones which continue to be made in the presence of sufficient hydroxyurea to depress DNA synthesis almost totally has been studied. Deposition seems to be on material which absorbs at 260 nm. This material is not a part of the bulk chromatin and binds histone in a relatively tight manner. The possible role of such a material in histone synthesis and deposition is discussed.

Cell Line↗

PubMed1977

Comparative study of rye and thymus histones: amino acid analysis and tryptic fingerprinting.

Amino acid composition and tryptic fingerprints of rye (Secal cereale) H1, H2B (PH1), and H2A(PHII) histones indicate the presence of major differences between these and the corresponding calf or rabbit fractions. In addition to variations for other amino acids, fraction H1 from rye contains twice as much arginine as the corresponding animal fraction; the plant H2B (PHI) and H2A (PHII) histones show lysine to arginine ratios greater than those of their animal counterparts. The tryptic maps of the same proteins appear to differ between plants and animals by the number and the general pattern of the peptides, as well as by the quantity and distribution of the arginine-containing peptides. Such results suggest the presence of differences in the primary structure of the calf and rye lysine-rich and moderately lysine-rich histones. Furthermore, the possibility is ruled out that each of these plant histones consists of an animal-like protein with an additional segment of 20--30 amino acid residues. On the other hand, the rye and calf arginine-rich fractions H3 and H4 show similar amino acid compositions and tryptic peptides maps.

Amino Acids↗

PubMed1976

Vertical fracture dislocation of the tarsal navicular.

An isolated vertical fracture dislocation of the left tarsal navicular with some comminution was successfully treated with open reduction and internal fixation with a screw. The surgical treatment is described, and early mobilization strongly recommended.

Adult↗

PubMed1973