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Biomedical subjects

F Lamy

Publications and source records attributed to F Lamy.

At least 73 records · Page 4Linked to original sources
PubMed1981

Guanidination of the lysine residues present in fibrous elastin and in soluble elastin peptides.

We have found that only 20 to 30% of the lysine residues measured after acid hydrolysis of insoluble elastin and alpha-elastin were blocked by prior guanidination of elastin with o-methylisourea. In contrast free lysine was guanidinated almost 100% and a purified, highly crosslinked peptide fraction of low molecular weight, 85%. The non-reactivity of lysine does not seem to be due to steric hindrance in the fibrous protein or in the large peptides derived therefrom but rather to the presence of epsilon [delta-adipic acid]-lysine, the oxidized form of lysinonorleucine described by Bailey et al. Since photolysis of desmosine and isodesmosine leads also to the formation of new lysine residues, methods will have to be devised to distinguish lysine-containing peptides derived from photolyzed elastin.

Amino Acids↗
PubMed1980

Controlled trial of cimetidine in reflux esophagitis.

In an eight-week double-blind trial, the effectiveness of cimetidine (1.6 g/day) was compared to placebo in 34 patients with symptomatic esophagitis confirmed by endoscopy with biopsies and/or by acid infusion test. Patients treated with cimetidine had significantly less symptomatic days during the first six weeks and less symptomatic nights during the first two weeks, and they consumed less antacids during the whole trial period. Endoscopic evaluation of 17 patients on cimetidine and of 15 patients on placebo did not show any significant difference in severity and extent of esophageal lesions after eight weeks, but histological assessment of 16 patients on cimetidine and 13 patients on placebo showed a significant improvement after eight weeks of cimetidine (P < 0.025). These results show that cimetidine has a rapid effect on symptoms of reflux esophagitis and that, in some cases, it may reduce the esophageal lesions after eight weeks.

Administration, Oral↗
PubMed1979

Photodesmosine, an isomer of desmosine obtained by photolysis of this amino acid in ultraviolet light.

Desmosine and isodesmosine are two isomers representing the main crosslinks of elastin. We describe a new isomer, photodesmosine, which is produced by the photolysis of desmosine at 254 nm. The mechanism of this photolysis is described and is shown to consist of two competing paths. After opening of the pyridinium ring to give a tetrasubstituted aminoketone, this compound can either be hydrolysed to give lysine and a trisubstituted analogue of glutaconic aldehyde or undergo a recyclisation and rearomatisation to give a pyridinium compound substituted in positions 1, 2, 3 and 4. An understanding of this mechanism is important in order to use photolysis as a specific method to break elastin cross-links. Although only desmosine and isodesmosine have been reported in purified elastin, the chromatographic properties of photodesmosine suggests that if other natural isomers exist in this protein they could be eluted from an ion-exchange resin at much earlier times than those observed in the case of the two already described cross-links.

Amino Acids↗
PubMed1979

Nature of the phosphorylated 26 000 molecular weight protein extracted from dog thyroid with contractile proteins.

Dog thyroid contractile proteins are characterized by their ATPase activity at high KCl concentration. In the presence of Ca(2+), 80 nmol ATP are hydrolyzed per min per mg protein. This Ca(2+) -ATPase activity is inhibited by Mg(2+) but not influenced by sodium azide. The 26 000 molecular weight protein which is present in thyroid contractile protein preparations and the phosphorylation of which is stimulated by thyroid stimulating hormone (TSH) is suggested to be identical to the lysine-rich histones (H1). Indeed, radioactive thyroid H1 histones added to unlabelled thyroid slices copurify with the contractile proteins and migrate at the same level as the 26 000 molecular weight when submitted to electrophoresis in polyacrylamide sodium dodecyl sulfate gels of different acrylamide concentrations.

Animals↗
PubMed1979

Pattern of protein phosphorylation in intact stimulated cells: thyrotropin and dog thyroid.

Two-dimensional, high-resolution electrophoretic technique of O'Farrell has been adapted to the analysis of thyroid phosphorylated proteins. Proteins were extracted from dog thyroid slices which had been incubated in the presence of [32P]phosphate with thyrotropin or with different agents which enhance the intracellular accumulation of cyclic AMP. About 350 phosphorylated polypeptides have been separated. Thyrotropin stimulates the phosphorylation of at least eight of these polypeptides. An increase in the phosphorylation of the same polypeptides was observed was observed when dog thyroid slices were incubated with dibutyryl adenosine 3':5'-monophosphate, cholera toxin or prostaglandin E1 instead of thyrotropin. Our results confirm that most of dog thyroid protein phosphorylation is independent of cyclic AMP. They offer a first link between the action of cyclic AMP on protein kinase and the physiological effects of thyrotropin. They strongly substantiate the hypothesis that most thyrotropin effects are mediated by cyclic AMP.

Animals↗
PubMed1978

Some properties of a Ca2+- and (or) Mg2+-requiring nucleoside di- and tri-phosphatase(s) associated with the membranes of rat pancreatic zymogen granules.

Membranes of rat pancreatic zymogen granules have been purified and found to be essentially free of contamination by mitochondria, microsomes, and plasma membranes. They possessed an acid phosphatase activity which derived probably from lysed lysosomes contaminating the purified zymogen granules from which the membranes were prepared. These membranes were found to contain a strong Ca2+- and (or) Mg2+-requiring activity toward all nucleoside di- and tri-phosphates. Various data support the tentative conclusion that a single protein catalyzes the hydrolysis of the nucleoside di- and tri-phosphates. This protein appears to be intrinsic with its active site localized on the internal face of the membranes.

Adenosine Triphosphatases↗
PubMed1978

Action of thyrotropin on phosphate incorporation into thyroid proteins in vitro.

It is now well established that cAMP is the intracellular mediator of many effects of thyrotropin on the thyroid. Greengard has postulated that all the effects of cAMP inside the cell are secondary to the phosphorylation of proteins by cAMP activated protein kinase(s). The purpose of our work is to define, in an intact cell system, the nature of the thyroid proteins, the phosphorylation of which is stimulated by cAMP and TSH.

Animals↗
PubMed1978

Collagen in 155 human bladders.

The percentage of bladder collagen, as obtained by the dosage of hydroxyproline, was determined in autopsy specimens from 48 female and 107 male cadavers. The average percentage of collagen in the human bladder is 57.4 per cent (+/- 9) of the dry weight of insoluble protein. There is good correlation (r = 0.55) between detrusor and trigone collagen content. There is no significant difference between pre- and postpuberty age groups in relative collagen content. In females more than 50 years of age there is a significant increase in collagen.

Adolescent↗
PubMed1977

Thyrotropin stimulation of a thyroid contractile protein phosphorylation.

Contractile proteins were isolated from preincubated dog thyroid slices by a procedure identical to the one used for the preparation of muscle actomyosin. At least two of these proteins (molecular weight = 26000 and 15000) were phosphorylated in the intact cell system. After one hour of incubation of the slices with thrytropin (10 mU/ml) and [32P]phosphate, the specific activity of the 26000-Mr protein was increased by a factor of three while no significant change in specific activity was observed in the 1500-Mr contractile protein. This effect of thyrotropin was already observed after 30 min of action, was elicited at hormone concentrations of the same order as those required to induce secretion and has been reproduced by dibutyryl adenosine 3':5'-monophosphate. Cycloheximide (0.35 mM) which almost totally inhibited protein synthesis in thyroid slices, did not affect the thyrotropin stimulation of the phosphorylation of the 26000-Mr protein. The phosphorylation of serine residue(s) has been demonstrated in this protein but the presence of radioactive phosphothreonine could not be detected. On the basis of its molecular weight, the 26000-Mr protein could be similar to the inhibitory component of muscle troponin complex (TN-I).

Animals↗
PubMed1977

Thyrotropin stimulation of the phosphorylation of serine in the N-terminal of thyroid H1 histones.

The analysis of thyroid nuclear proteins by polyacrylamide gel electrophoresis has demonstrated that thyrotropin and dibutyryl adenosine 3':5'-monophosphate stimulate specifically the phosphorylation of H1 histones in an intact cell system. This effect does not require new protein synthesis and implicates the phosphorylation of secrine residue(s) situated in the N-terminal part of H1 histones.

Animals↗
PubMed1977

Chymotrypsinogen D, a new zymogen from porcine pancreas with proelastolytic activity.

During the purification of propancreatopeptidase E, a proATEEase activity is always copurified. The proelastolytic and proesterolytic activities can be separated on a hydroxylapatite column. The zymogen with potential ATEEase activity has a basic isoelectric point, can be activated by trypsin, and can hydrolyse elastin and ATEE but not ATAME. Its molecular weight is about 26,500 and the NH2-terminal sequence indicates clearly that it belongs to the chymotrypsinogen family, but that it is not chymotrypsinogen A, B, or C. We call it chymotrypsinogen D. Although both pancreatopeptidase E and chymotrypsin D can hydrolyse elastin, the synthetic substrate ATAME is attacked only by pancreatopeptidase E. Therefore, the peptide bonds in elastin cleaved by these two enzymes should be different.

Amino Acid Sequence↗