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Biomedical subjects

P Netter

Publications and source records attributed to P Netter.

At least 181 records · Page 10Linked to original sources
PubMed1991

Assay of circulating hyaluronic acid in the rat: study of diurnal variation and effect of anesthesia.

Serum hyaluronic acid (HA) may provide a good marker for the severity of joint disease in the rat since a positive correlation was observed in experimental models of arthritis. However, little is known about its physiological variation in rats. In the present work, we do not find any circadian rhythm of HA in healthy Sprague-Dawley rats in contrast to that observed in humans, whose serum levels vary during daytime. Furthermore, the influence of blood sampling conditions on HA concentrations was evaluated in conscious animals and by using different anesthetics. The greater reproducibility for the assay of HA is observed with the intracardiac puncture under ether inhalation. Blood sample collection in the absence of anesthesia leads to a significant increase in serum levels of HA, which could be attributed partly to enhanced joint movements generated by psychological stress.

Analysis of Variance↗
PubMed1990

Intragenic suppressors reveal long distance interactions between inactivating and reactivating amino acid replacements generating three-dimensional constraints in the structure of mitochondrial cytochrome b.

Revertants of nonfunctional cytochrome b mutants were isolated and characterized to determine how specific deleterious mutations in cytochrome b can be suppressed by secondary mutations not restoring a wild type protein. It was recently shown that the cytochrome b function can be recovered following various pseudo-wild type reversions at the level of the original site mutation or adjacent positions (di Rago, J.-P., Netter, P., and Slonimski, P. P. (1990) J. Biol. Chem. 265, 3332-3339). In the present study, we describe how the cytochrome b function can be recovered by secondary mutations in positions which are removed from the original mutation by up to more than 100 amino acids. Such revertant mutants are useful for the study of the three-dimensional structure of cytochrome b. The results of the analysis of four deficient mutations which affect a short region of the protein (positions 131-138 of the polypeptide chain) lead us to propose a possible mode of interactive combination between the first five putative transmembrane segments of cytochrome b within the membrane.

Amino Acid Sequence↗
PubMed1990

Pseudo-wild type revertants from inactive apocytochrome b mutants as a tool for the analysis of the structure/function relationships of the mitochondrial ubiquinol-cytochrome c reductase of Saccharomyces cerevisiae.

We have analyzed the structure/function relationships of the yeast mitochondrial cytochrome b with a new methodology based upon the isolation of pseudo-wild type revertants from well-characterized cytochrome b respiratory deficient mutants. Our goal was to determine how cytochrome b function could be restored in such mutants, at least to some degree, by suppressor mutations within the protein. True wild type revertants were differentiated from pseudo-wild type revertants by the use of a simple and rapid screening technique based upon oligonucleotide hybridization. This can easily be used to analyze a large number of revertants. The suppressor mutations responsible for the restoration of respiratory competence were identified by sequencing the revertant's cytochrome b mRNA in crude mitochondrial RNA preparations. Using this new method we have analyzed 210 independent revertants. We report here nine novel cytochrome b structures conferring a variety of respiratory sufficient phenotypes, obtained from five respiratory deficient mutations affecting a short region of the protein (positions 131-138 of the polypeptide chain), presumably belonging to the ubiquinol oxidizing center of the bc1 complex.

Amino Acid Sequence↗
PubMed1990

Drug assay in ground tissues: example of ketoprofen diffusion into tonsillar tissue.

Ketoprofen was assayed in tissues of surgical patients after mechanical grinding of the tissue in liquid nitrogen; the fine powder obtained allowed the drug to be determined by HPLC in the same way as for liquid samples. The method was applied to the study of ketoprofen diffusion into the tonsillar tissue of 15 patients after a single intramuscular injection of ketoprofen (100 mg). A correction was made for blood contamination after hemoglobin determination.

Adolescent↗
PubMed1990

Plasma and cerebrospinal fluid concentrations of indomethacin in humans. Relationship to analgesic activity.

Plasma and cerebrospinal fluid (CSF) concentrations of indomethacin have been determined in 52 patients hospitalized for nerve-root compression pain. Samples of blood and CSF were collected at the same time in each subject, 0.5 to 12 h after a single intramuscular injection of 50 mg indomethacin. Analgesic effect was assessed by the absolute and percentage variation in Huskisson's visual analogue scale between dosing and sampling. According to its high lipid solubility, indomethacin rapidly crossed the blood-brain barrier, being detected in CSF 0.5 h after administration. After attainment of equilibrium within 2 h, the CSF level exceeded the free plasma level. Since the drug was extensively bound to serum albumin (99.7 +/- 0.1%), this phenomenon may represent a slight degree of binding of indomethacin in CSF. The analgesic activity was not related to either the plasma or CSF concentration of indomethacin.

Adult↗
PubMed1990

Mechanism of 3' splice site selection by the catalytic core of the sunY intron of bacteriophage T4: the role of a novel base-pairing interaction in group I introns.

The catalytic core of the sunY intron of bacteriophage T4 is separated from its 3' exon by 837 nucleotides, most of which are part of an open reading frame (ORF). Here, we report that transcripts truncated within the sunY ORF self-splice in vitro to a variety of sites in the segment immediately 3' of the core. Recognition of these proximal splice sites is shown to depend on (1) the presence on the intron side of a terminal G, which must not be part of a secondary structure; and (2) the ability of the penultimate intron nucleotide to base-pair with a 3' splice site-binding sequence (3'SSBS) located within the core. The counterpart of the 3'SSBS can be identified in most group I introns. The possible significance of such alternative splicing events for in vivo expression of intron-encoded proteins is discussed.

Base Composition↗
PubMed1990

Pharmacological aspects of chiral nonsteroidal anti-inflammatory drugs.

Most NSAIDs are chiral molecules: they exist under 2 configurations of non-superimposable mirror images which are termed enantiomers or optical isomers or optical antipodes. Direct or indirect (resolution) methods are used to separate this equal mixture of compounds. Some of the enantiomers of the NSAIDs are able to undergo chiral inversion from the inactive R(-) to the active S(+) form. The pharmacokinetics in terms of absorption, distribution, metabolism, protein binding and elimination may be different for the 2 enantiomers, leading to interindividual variability in clinical response and drug toxicity.

Animals↗
PubMed1990

Personality related differences in response to 5-HT uptake inhibition.

Conflicting results on clinical effects of serotonergic drugs gave rise to this investigation on the relationship between depression-related personality factors and effects of the 5-HT uptake inhibitor fluoxetine on psychomotor functions and emotional states. In a double-blind, balanced, crossover design, 24 healthy male subjects divided according to scales of "Experiencing of Stress" and "Neuroticism," were tested with a single dose of 60 mg fluoxetine or placebo. Reaction time and feelings of activation and energy of highly neurotic or stressed subjects were deteriorated by fluoxetine while emotionally stable subjects were improved by the drug. The findings were interpreted in terms of personality related differences in 5-HT neurotransmission and receptor sensitivity.

Adult↗
PubMed1990

[Osteo-articular manifestations in dialysis of patients over 70 years].

A clinical, biological and radiological prospective study was carried out in 21 patients over 70 years of age and treated by hemodialysis or chronic ambulatory peritoneal dialysis (CAPD) to evaluate the frequency and specificity of rheumatic diseases observed in aged chronic renal failure patients. Some are caused or favored by old age and are not in any way related to renal failure and its replacement therapy. Such was the case with arthrosis which was present in 85% of patients, ankylosing vertebral hyperostosis (14%), Paget's disease (5%) and gouty arthritis (10%). Elsewhere there is an implication between abnormalities due to aging and those linked to renal failure and/or dialysis, some of which can worsen or accelerate others. Secondary hyperparathyroidism seems less frequent in the elderly than in the young patients. Common vitamin dependent osteomalacia should not be neglected because it can be either prevented or efficiently treated. Osteoporosis is another important factor in osteopenia. Extra-skeletal calcifications are frequent: periarticular calcifications (38%), chondrocalcinosis (14%) and disc calcifications (24%). Dialysis arthropathy comprising: carpal tunnel syndrome, erosive lesions of large and intermediate limb joint articulations and destructive spondylarthropathy is observed in 43% of patients after an average dialysis period of 44 months. The advent of this complication seems to be quite early in the elderly, as compared to the young population, which confirms the role played by age as a favoring factor.

Aged↗
PubMed1990

The effect of ethanol on stress-induced tachycardia.

A study was designed to answer the questions if low doses of ethanol would reduce stress induced increases in heart rates, if covariations would be observed between ethanol induced changes in heart rates and changes in emotional states and mental performance and if tolerance to ethanol or other personality factors would influence the ethanol induced cardiac effects. Forty-four male students with a history of high and low alcohol consumption according to questionnaire scores were matched for extraversion and neuroticism and then assigned to a group receiving either 0.8 g/kg of ethanol or a placebo drink. A stress condition of mental arithmetic was applied prior to and 45 minutes after ingestion of the drink. Heart rates and ratings of emotional states by adjective check lists were recorded before and after each stress session. A significant reduction of stress induced heart rate increases in both high and low drinking groups but no ethanol dependent change of resting heart rates were observed. Reductions of autonomic stress response by ethanol were weakly but positively correlated to respective reductions of affective stress responses and impairment of the quality of mental performance. High trait anxiety subjects seemed to benefit more from ethanol with respect to reductions of cardiac and emotional arousal than low anxious subjects.

Adult↗