Biomedical subjects

M Haimart

Publications and source records attributed to M Haimart.

9 recordsLinked to original sources

PubMed1994

Increase of human platelet serotonin uptake by atypical histamine receptors.

Histamine and the guanosine 3',5'-cyclic monophosphate (cGMP)-inducing agent sodium nitroprusside both increased serotonin (5-HT) uptake and cGMP levels in isolated human platelets in vitro. Histaminergic stimulation was observed at concentrations ranging from 10 nM to 0.25 microM [mean effective concentration (EC50) = 0.1 microM histamine]. The inhibition produced by the H2-receptor antagonists tiotidine, metiamide, and cimetidine was 10-10(5) times more potent on histamine receptors regulating 5-HT uptake and cGMP generation in human platelets than on the histaminergic receptors H1, HIC, H2, and H3 in other tissues. The in vitro histamine-induced 5-HT uptake was prevented by preincubation of isolated human platelets in the presence of the nitric oxide synthase inhibitor NG-monomethyl-L-arginine or the cGMP-lowering agent LY-83583. Histamine was ineffective in stimulating cAMP generation in human platelets and did not interact with effector sites known to downregulate 5-HT uptake, including imipramine, gamma-aminobutyric acid A, peripheral type benzodiazepine-binding sites, and V1a vasopressin receptors inducing human platelet shape change and aggregation. These atypical human platelet histaminergic receptors differ from the previously classified histamine receptors by their apparent high affinity to histamine H2-receptor antagonists and their apparent link with the soluble, nitric oxide-dependent guanylate cyclase. These findings suggest that human platelets express a new subtype H2h of histamine receptors.

Adult↗

PubMed1988

Serotonin metabolism and other biochemical parameters in infantile autism. A controlled study of 22 autistic children.

The serotonin metabolism was extensively studied in 22 couples of autistic children and age- and sex-matched controls. Histamine, calcium, and uric acid were also measured in urine and whole blood or plasma. Autistics and controls did not differ in histamine, and only minor changes were noticed in calcium content. According to previous reports, serotonin levels were often, but not always, elevated in the blood of autistic children. Based on data including urinary serotonin and 5-hydroxyindoleacetic acid, platelet serotonin uptake and efflux, platelet monoamine oxidase and glutathione peroxidase activities, and uric acid and plasma tryptophan, the origin(s) of such hyperserotonemia in autism appear(s) to be of metabolic origin, i.e., a decreased catabolism and/or an increased biosynthesis of serotonin.

Adolescent↗

PubMed1987

Whole blood and plasma histamine in common migraine.

Whole blood and plasma histamine levels were measured in 27 non-medicated patients with common migraine. In nine cases blood was drawn 1-2 h after the onset of a migraine attack. The whole blood histamine levels of migraineurs and controls did not differ significantly. In contrast, histamine levels were significantly increased in plasma from patients both during and between migraine attacks, as compared with controls (p less than 0.001). Finally, plasma taken from migraine patients induced a significantly greater release of histamine from control whole blood than did plasma taken from control subjects (p less than 0.01).

Adolescent↗

PubMed1985

Simultaneous determination of histamine and N alpha-methylhistamine in biological samples by an improved enzymatic single isotope assay.

A modified highly sensitive and specific radioenzymatic assay for the simultaneous determination of histamine (HA) and N alpha-methylhistamine (N alpha-MH) in tissues and body fluids is described. In the presence of the enzyme histamine-N-methyltransferase and of the methyl donor [3H]-S-adenosylmethionine, the transmethylation process was about seven times more effective for HA than for N alpha-MH. In the same conditions only very low amounts of N alpha, N alpha-dimethylhistamine (N alpha, N alpha-DMH) were converted into its 1-methylated derivative. The high degree of specificity attained by this method is due to the rapid quantitative extraction of the biological fluids, to the partially purified enzyme preparation and to the thin-layer chromatography system used which allows an excellent separation of the 3H-1-methyl products of HA, N alpha-MH and N alpha, N alpha-DMH. This method is highly sensitive for the assay of HA and N alpha-MH (detection limit 10 and 50 picograms, respectively), but due to lack in sensitivity, it cannot be extended to the measurement of N alpha, N alpha-DMH. The HA content of 20-30 samples can be determined in duplicate by one person in a working day. The concentrations of HA measured by this method in different biological samples (human whole blood, plasma, urine, gastric juice and skin biopsies) were in good agreement with the values reported in the literature. The presence of minute amounts of N alpha-MH in the human gastric juice was established by rigorous checking.

Body Fluids↗

PubMed1985

Effects of in vitro infection of mouse glial and neuroblastoma cells with the scrapie agent.

Mouse glial and neuroblastoma cells were infected with the mouse adapted strains C506 and 139A of scrapie agent. Lysates of the in vitro infected cells (from the 3rd to the 16th passage) intracerebrally inoculated into CD-1 mice, caused the development of a neurological disease, with characteristic signs of scrapie. Morphological changes in scrapie-infected neural cells were observed after about fifteen in vitro passages. In liquid medium, the cloning efficiency of these cells increased. They acquired the capacity to form large tridimensional colonies in agar. Heating the infectious brain extracts at 60 and 80 degrees C for 30 minutes did not inhibit these changes thus showing the involvement of the thermoresistant scrapie agent. Supernatants of scrapie-infected glial cells promoted colony formation in liquid medium with different types of normal cells. Analysis of supernatants of scrapie-infected mouse neuroblastoma cells showed a profound modification of neurotransmitter metabolism.

Animals↗

PubMed1984

[Blood serotonin and histamine in sheep with endemic scrapie: initial results].

The whole blood histamine levels of sheep without clinical scrapie but living in infected farms, control, and scrapie infected sheep are not significantly different. By contrast whole blood serotonin is decreased both in sheep living in infected farms and in scrapie-infected sheep as compared to controls. Thrombopenia may account for the hyposerotoninemia of sheep living in infected farms except those genetically linked to scrapie-infected sheep for which, as for scrapie-infected sheep, platelet serotonin appears also to be diminished. Whole blood serotonin determination might therefore be useful to detect sheep living in infected farms (these sheep probably play an important role in scrapie infection) and perhaps also humans with high susceptibility to Creutzfeldt-Jakob disease.

Animals↗

PubMed1983

The diffuse neuroendocrine (APUD) system.

The bulk of experimental evidence indicates that the APUD series of cells is a distinct system based upon common pathophysiological features. The diffuse nature of this system with elements in the central and peripheral nervous system suggests a more complex interaction of the body's homeostasis than has been established. It is probable that as radioimmunological and radioenzymatic assays become more widely available and standardized, other apudomas will be described. Finally, an understanding of the APUD concept, with its peculiar pluripotential for the production of biogenic amines and peptides, the multicentric nature of the disease and the possibility of multiple cell involvement, is of key importance in managing patients. Studies of the apudomas will also advance the understanding of the normal physiologic interrelationships of the APUD cells.

APUD Cells↗

PubMed1982

Post-menopausal concentrations of plasma oestradiol, oestrone, FSH and LH and of total urinary oestradiol and oestrone after a single sublingual dose of oestradiol-17 beta.

We report the effects of sublingual absorption of a single dose (0.5 mg) of oestradiol-17 beta (E2) in 8 post-menopausal women, on plasma E2 and oestrone (E1), urine elimination of total E2 + E1 and on plasma FSH and LH. The results show that sublingual absorption of E2 occurs and that plasma concentrations of E2 obtained (between 133.2 to 320 pmol/l) in this way were higher than those obtained after percutaneous absorption of a single dose (3 mg) of E2. The ratio E1/E2 in plasma is close to that of pre-menopausal women.

Absorption↗

PubMedDate not supplied

[Histamine-release and migraine].

Some studies suggested a role for histamine in the pathogenesis of the migraine. So we decided to investigate the histamine-release in two groups of patients: 8 common migraine patients, 8 healthy subjects. Plasma from either controls or migraineurs were mixed with the same control whole blood and histamine release was measured using a radio-enzymatic assay. Migraine plasma induced an histamine release significantly more important than control plasma (p less than 0.01). The nature of an "histamine releasing factor" in the plasma of migraine patient is discussed. This work is an argument for a possible immuno-allergic process in migraine.

Adult↗