Search PubMed⌕ Search

Biomedical subjects

J O Peyrin

Publications and source records attributed to J O Peyrin.

At least 19 recordsLinked to original sources
PubMed1990

Environmental optimization and shielding for NMR experiments and imaging in the earth's magnetic field.

For many years, a number of laboratories have been working on the applications of very low field NMR. In 1985, our laboratory presented the first NMR images using the earth's magnetic field. However, the use of this technique was limited by the weakness of the signal and the disturbing effects of the environment on the signal-to-noise ratio and on the homogeneity of the static magnetic field. Therefore experiments has to be performed in places with low environmental disturbances, such as open country or large parks. In 1986, we installed a new station in Lyon, in the town's hostile environment. Good NMR signals can now be obtained (with a signal-to-noise ratio better than 200 and a time constant T2 better than 3s for 200-mnl water samples and at a temperature of about 40 degrees C). We report the terrace roof of our faculty building. Gradient coils were used to correct the local inhomogeneities of the earth's magnetic field. We show FIDs and MR images of water-filled tubes made with or without these improvements.

Environment↗
PubMed1990

Radioisotopic and biochemical determination of salivary secretion after long term psychotropic therapy.

The aim of this work was to investigate the effect of prolonged psychotropic therapy (neuroleptics and antidepressants over 5 yr on salivary secretion. The flow rate in the parotid and submandibular glands were measured separately by scintigraphy. Flow rates, total protein concentration and total IgA level were determined in the unstimulated saliva in 30 control subjects and 73 patients treated with psychotropic drugs. As evidenced by measurement of flow rates and scintigraphy, psychotropic therapy reduced the unstimulated salivary secretion from parotid glands and to a lesser extent from submandibular gland. The scintigraphic study showed a lower response to stimulation in patients than controls.

Humans↗
PubMed1990

[Modifications, due to nutrition, of methyl and methylene 1H NMR signals in human plasma and normal serum samples].

The line width test has been realised on twelve normal healthy persons (seven men and five women). Blood was collected at different time during one day. The results obtained when blood samples was taking after eating, showed an appreciable decrease in the average methylene and methyl line width. The same test realised on clear serum samples added up with increasing quantities of triglycerids rich lipoproteins leads to the same result.

Blood Chemical Analysis↗
PubMed1989

Preliminary results of nuclear magnetic resonance studies of healthy human saliva.

Relaxation times T1 and T2 of water protons for stimulated and unstimulated parotid and submandibular saliva from healthy patients were measured in the conventional way using the Bruker PC 20 Minispec. Some measurements of dispersion were also carried out. An interpretation of the average values for T1 and T2 observed in the 20 MHz range is proposed for these types of saliva in relation to biochemical composition (total proteins, amylase activity, sialic acids and hexosamins) and viscosity. For parotid saliva T2(-1)-T1(-1) correlates significantly with amylase activity. In the submandibular saliva T2(-1)-T1(-1) correlates significantly with both mucins and alpha-amylase activity.

Amylases↗
PubMed1986

[Erythrocyte-plasma water exchange studied by nuclear magnetic resonance spin-spin (T2) relaxation. Relation between the time the water molecule stays in the erythrocyte and its volume].

A simple, precise and rapid pulse nuclear magnetic resonance technique for measuring the rate of water exchange across the erythrocyte membrane is presented. The effects of cell volume on cell water lifetime may be eliminated by the introduction of a cell water diffusion coefficient. This parameter is applied to the study of eleven blood samples.

Body Water↗
PubMed1982

Low field topical nuclear magnetism apparatus in a hospital area.

We describe the technique and the measure of the relaxation time T2 for the free precession of protons in the earth field. In vitro and in vivo experiments on human physiological fluids, including blood coagulation, are reported. We put forward the evident interest of this technique to study the meconium in the amniotic liquid and small quantities of oscite observed in situ.

Amniotic Fluid↗
PubMed1981

Human serum albumin labelled with 99Tcm and 131I for total blood volume determination: A critical and comparative analysis in vivo and in vitro.

The increased plasma volume or total blood volume determined with radioactive tracers often have no physical or pathologic explanation. The plasma volume and blood dilution were simultaneously measured in 5 patients who had received human serum albumin labelled with 99Tcm or 131I. In each case and for each tracer, a biexponential dilution curve was obtained. The measured plasma volume was consistently higher after 99Tcm-labelled albumin. The results are correlated with the presence of non-protein artifacts arising from the labelling process and proteinaceous compounds arising from denaturation.

Blood Volume Determination↗
PubMed1979

[Pathogenesis of reflex secretory dysfunctions. Value of isotopic techniques (author's transl)].

Many hypotheses have been advanced to try to explain the mechanism involved in reflex secretory dysfunctions. The use of dynamic isotopic techniques and their application in clinical research enable a more precise approach to be made to assist in solving the problem. Using several examples of dysfunction of various etiologies, the authors demonstrate the existence of an excretory blocking effect from parasympathetic inhibition.

Atropine↗
PubMed1975

[Radioisotopic examination and diagnosis of dryness of the mouth].

The clinical and sialographic opposition between true xerostomia (with continuous disorders) and paradoxical asialia (with inter-prandial disturbance, but sparing mealtime) led the authors to analyze these patient's scintigraphic scannings. A kinetic study of excretion was carried out with gamma-camera recording of intensity and glandular activity: the information thus obtained was set down in a numerical integration block and dealt with by computer. A graph of activity was plotted for each gland showing: - a phase of ascending concentration followed by a plateau corresponding to excretion at rest; - a phase of excretion provoked by a gustatory stimulus (physiological) with a very rapidly descending graph. It is possible to establish a ratio of glandular activity/blood activity at maximum concentration and maximum excretion. From the graphs thus obtained it is possible to perfectly differentiate true xerostomia (no excretion even with stimulation) from paradoxical asialia (no plateau of excretion at rest, but stimulus effective). A better knowledge of "dryness of the mouth" should enable better adapted therapy.

Diagnosis, Differential↗
PubMed1975

[Radioimmunoassay without extraction of L-triiodothyronine in human serum].

A radio-immunoassay of L-triiodothyronin is described. Blinding of T3 to TBG is prevented by salicylate (1%--w/v). The rabbit antiserum obtained by injection of a complexe T3-bovine serum albumin is diluted between 1/10000 and 1/20000. Bound and free hormone are separated by polyethylene glycol (17%--w/v). Serum T3-concentration in normal subjects averaged 132 +/- 29 ng/dl (SD). In hyperthyroid and hypothyroid patients, these values were respectively 351 +/- 118 ng/dl and 68 +/- 21 ng/dl.

Humans↗