Search PubMed⌕ Search

Biomedical subjects

J Legrand

Publications and source records attributed to J Legrand.

At least 19 recordsLinked to original sources
PubMed2000

Influence of flow patterns on chromatographic efficiency in centrifugal partition chromatography.

Visualization of flow patterns in centrifugal partition chromatography (CPC) was performed with an asynchronous camera and a stroboscope triggered by the CPC rotor, allowing a channel to be selected and observed regardless of rotational speed. Three main types of flow states were noted as a function of rotational speed and flow-rate: jets stuck along channel walls, broken jets and atomization. Our observations emphasize the importance of Coriolis force on flow shape. Chromatographic efficiency was related to the dispersion of the mobile phase in the stationary phase.

Centrifugation↗
PubMed1998

Subdoppler Study of the nu7 Band of C2H4 with a CO2 Laser Sideband Spectrometer

The saturation spectrum of ethylene has been studied between 900 and 1100 cm-1 with the sub-Doppler sideband spectrometer of Lille. Two hundred absorption lines have been recorded with an absolute accuracy of approximately 15 kHz. On the basis of these accurate data, a new global analysis of the GS and of the nu7, nu10, and nu4 upper states was achieved taking into account the Coriolis interactions up to the third order. A statistical agreement is obtained with all experimental data with an estimated standard deviation equal to 0.825. The spectra of ethylene between 900 and 1100 cm-1 become very good wavenumber standards with an absolute accuracy of 10(-6) cm-1. Copyright 1998 Academic Press.

Journal Article↗
PubMed1998

Saturation Sideband CO2 Laser Spectroscopy of the Overtone Band 2nu2 and Its Hot Band 3nu2-nu2 of Carbonyl Sulfide.

The saturation spectra of the 2nu2 and the 3nu2-nu2 bands of carbonyl sulfide have been studied using a CO2 laser sideband spectrometer. The frequency of 20 absorption lines has been determined with an accuracy of 20 kHz. These data have been included in a global rovibrational analysis including all the other data available on 16O12C32S. We list an improved set of standard frequencies at the 10(-6) cm-1 level. Copyright 1998 Academic Press.

Journal Article↗
PubMed1998

Double Resonance Sub-Doppler Study of the Allowed and DeltaK = -3 Forbidden Q(3, 3) Transitions to the nu2 Vibrational State of 14NH3.

The IR-IR sub-Doppler double resonance and standard saturation sideband spectroscopy have been used to measure the allowed and Deltak = -3 forbidden transitions to the nu2 vibrational level of 14NH3. The IR-IR double resonance technique has made it possible to observe quadrupole hyperfine structures which correspond to the sums as well as differences of the -3Q(3, 3) and Q(3, 3) hyperfine components. The "sum" and "difference" double resonance frequencies have been measured with accuracy better than 30 and 5 kHz, respectively. In addition to this, the hyperfine structure of the allowed Q(3, 3) transition has been independently measured using the "standard" saturation sideband spectroscopy with accuracy better than 15 kHz. A simultaneous analysis of all measured data provides an improved set of effective nuclear quadrupole and spin-rotation parameters for the excited nu2 vibrational state and frequencies of the "pure" rotation-vibration transitions deperturbed from the hyperfine effects at the experimental sample pressure of about 3 mTorr, including a very precise zero pressure value of the "forbidden" spacing between energies of the nu2 ||s, J = 3, K = 3> and ||s, J = 3, K = 0> pure rotational levels of 2883.6795(19) MHz [0.096189194(63) cm-1]. Copyright 1998 Academic Press.

Journal Article↗
PubMed1994

Monitoring biological effects of contamination in marine fish along French coasts by measurement of ethoxyresorufin-O-deethylase activity.

The use of bioindicators to evaluate exposure to the biological effects of chemical pollutants in marine organisms constitutes a new tool in the monitoring field. The establishment of a North Sea monitoring network in 1991, involving such international organizations as the North Sea Task Force, the International Council for the Exploration of the Sea, and the Intergovernmental Oceanography Commission, led French researchers to develop an enzymatic biomarker to monitor biological effects within the National Observation Network. The biomarker, ethoxyresorufin-O-deethylase (EROD), dependent on the CP450 system, has been monitored biannually since 1992 in several species of fish (Callionymus lyra, Limanda limanda, Serranus sp., Mullus barbatus) in two coastal sites particularly exposed to industrial and domestic pollution. A rapid method is used to assay EROD enzymatic activity determined along a pollution gradient, and results are interpreted on a microplate reader. The strategy of this approach is to assess the effects on the marine ecosystem during prolonged exposure to specific pollutants such as polyaromatic hydrocarbons, polychlorinated biphenyls, and dioxins.

Animals↗
PubMed1990

Duodenogastric reflux in patients with Barrett's esophagus.

The role of duodenogastric reflux in the pathogenesis of gastroesophageal reflux disease is not clear. Using hepatobiliary scanning techniques, we found evidence of duodenogastric reflux in six of 13 patients with Barrett's esophagus. This compares with only two positive studies in 19 control subjects. This difference is statistically significant (P = 0.038, two-tailed Fisher's exact test). Three of nine patients who had gastroesophageal reflux without Barrett's esophagus had evidence of duodenogastric reflux, a frequency not significantly different from either of the other groups. Gastroesophageal reflux of bile and pancreatic enzymes, in addition to gastric acid may contribute to the greater esophageal damage often seen in Barrett's esophagus. The presence of duodenogastric reflux in these patients may have important pathophysiologic and therapeutic implications.

Barrett Esophagus↗
PubMed1987

Morphometric analysis of the cerebellar Purkinje cell in the developing normal and hypothyroid chick.

A morphometric analysis of Purkinje cells in the developing cerebellar cortex of the chick was performed in normal animals and embryos made hypothyroid by one or two spaced injections of tetramethylthiourea. Profiles of 162 Purkinje cells, from Golgi-Cox treated sections were analysed. Soma area, perimeter and circularity index, cumulative length of the dendrites and number of dendritic bifurcations were studied. The results showed significant differences between control and hypothyroid animals. There were no important differences between birds rendered transiently hypothyroid with a single injection and those made chronically hypothyroid with dual injections. This confirms that the Purkinje cell is very dependent on thyroid hormone especially during the early phases of its morphogenesis. The development of the Purkinje cell was the most affected process of cerebellar cortex maturation in the thyroid-deficient chick. The dendritic arborization was particularly hypoplastic. Moreover, a dynamic balance appeared to exist between the development of the dendritic arborization and that of the perikaryon.

Animals↗
PubMed1985

Con A-binding glycoproteins in the developing cerebellum of control and hypothyroid rats.

Concanavalin A (Con A)-binding glycoproteins were studied during the postnatal development of the cerebellum of control and hypothyroid rats. Only 4 glycoprotein bands have a transient behavior in control animals. They progressively increase until the 13th day and markedly decline between the 15th and the 18th postnatal day. In the cerebellum of hypothyroid rats, the level of these compounds is greatly reduced and the previous decrease observed in controls is not found again. This defect of Con A-binding glycoproteins mainly localized on the plasma membrane of parallel fibers might be related to the reduced synaptogenesis observed in the molecular layer of hypothyroid rats between parallel fibers and Purkinje cell dendritic spines.

Age Factors↗
PubMed1983

Cochlear synaptogenesis in the hypothyroid rat.

The effects of congenital hypothyroidism on cochlear synaptogenesis were studied using transmission electron microscopy in 30 propylthiouracil-treated rat pups 1-35 days of age. No difference with controls was observed at the level of the inner hair cells which are known to mature essentially during the prenatal period. On the contrary, hypothyroidism resulted in numerous abnormalities in synaptogenesis at the level of the outer hair cells: abnormal persistence of numerous afferent dendrites and presynaptic specializations, incomplete development of efferent terminals and absence of formation of postsynaptic cisterns. It can be concluded that hypothyroidism results in severe retardation in the postnatal development of the innervation of outer hair cells.

Animals↗
PubMed1982

Influence of altered thyroid and nutritional states on early histogenesis of the rat cerebellar cortex with special reference to synaptogenesis.

On day of birth, the synaptic density of the rat cerebellar cortex in experimental, as compared to control, rats was slightly reduced or increased, respectively, after propylthiouracil treatment of the dam or thyroxine injection of the fetus. The stimulation of synaptogenesis in thyroxine-treated neonates was particularly obvious at the level of the ganglionic layer containing Purkinje cell bodies and was accompanied at the same level by accelerated growth of the presynaptic endings and perisomatic processes of the Purkinje cells. Undernourishment of the dam from day 6 of gestation led to an unexpected stimulation of synaptogenesis in the cerebellar cortex of the neonates; synaptic density was significantly increased above the normal value and much more markedly than in the thyroxine-treated neonates, but there was no abnormal proliferation of the neuronal processes. Different mechanisms underlay the transient stimulation of synaptogenesis in these two conditions. These results have been related to the disturbances in the development of Bergmann glia previously found soon after birth in altered thyroid and nutritional states.

Animal Nutritional Physiological Phenomena↗
PubMed1982

[The renin-angiotensin-aldosterone system and the adrenergic system in normal pregnancy and hypertension induced by pregnancy].

Plasma renin activity (PRA), plasma aldosterone (PA) and plasma catecholamines were measured in 3 groups of women with pregnancy of 20-38 weeks: group I of 16 normotensive controls, group II of 17 women with rest responding hypertension (RRH) and group III of 18 women with permanent hypertension (PH) (supine blood pressure greater than 140-90 mmHg after 8 days of rest, disappearing after delivery). Studies were realized on fasting ambulatory women on a normal salt diet. PRA (mean +/- SEM) was significantly higher in the RRH group than in the control and PH groups (15,8 +/- 2,3 ng/ml/h versus 6,7 +/- 0,5 and 8,9 +/- 0,9). PA was higher but not significantly in the RRH group (736 +/- 122 versus 533 +/- 52 and 502 +/- 103 pg/ml). Plasma epinephrine (PE) and norepinephrine (PNE) were significantly higher in the PH than in the control and RRH groups. 135 +/- 28 pg/nl versus 56 +/- 13 and 63 +/- 17 for PE and 387 +/- 91 versus 206 +/- 32 and 200 +/- 47 pg/ml). These data suggest that PH is linked with activation of the adrenergic system whereas RRH is linked with activation of the RAA system.

Aldosterone↗
PubMed1981

[Psychomotor disturbance after an endocular operation (author's transl)].

After an endocular operation, a mental derangement may happen in the next hours or next days; it's characterized by psychomotor disturbance, excitement, confusion in the time and the space, auditory and visual hallucinations. The consequence may be serious on general and ocular field. This syndrome is produced by the stress of the intervention with predisposed patients (artériosclerosis, old people, alcoholic patients, patients in a low strate). The change of the rythm of usual life, the temporary privation of the sensorial function favouring its appearance. To avoid it, it's advisable to reassure the future patient, to put him in a climate trust, and to avoid isolation during his stay in hospital. Post operational antialgics might be useful. During the confused state, the patient must not be living isolated. The sight must be recovered as soon as possible. One can add neurosedatives, but with precautions, and if it's electrolytic troubles, to fight it by an adequate reanimation.

Adult↗
PubMed1980

Analysis of the mechanisms underlying increased histogenetic cell death in developing cerebellum of the hypothyroid rat: determination of the time required for granule cell death.

The connection between the date of formation of granule cells and their final position in the internal granular layer of the cerebellum has been described previously. In rats made hypothyroid since the end of gestation, the distribution of the pyknotic cells in the internal granular layer of the cerebellar cortex was also previously found to be age-related. In 14-day-old hypothyroid rats, it was compared with that of the granule cells which were labeled after a pulse of [3H]thymidine at various stages of development. It appeared that the localization of the dying cells corresponded roughly to that of granule cells labeled on day 9. Therefore the maximum time required for granule cell death was about 5 days. Since the migratory phase through the molecular layer lasted about two days, the granule cells died after a maximum time of 3 days following their deposition in the internal granular layer. Information concerning the time of survival of the dying granule cells was important for subsequent investigation of the mechanisms underlying increased granule cell death in the hypothyroid cerebellum and the corrective effects of thyroid hormone.

Age Factors↗