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Biomedical subjects

C Julien

Publications and source records attributed to C Julien.

At least 91 records · Page 5Linked to original sources
PubMed1988

Prenatal diagnosis with biotinylated chromosome specific probes.

We have used a Y-chromosome specific DNA probe in a controlled study to determine the presence of Y-chromosome material and to detect numerical abnormalities in uncultured amniotic fluid cells by fluorescent hybridization. Using this non-radioactive method, we correctly predicted fetal sex within 48 h in all but 3 of 54 cases and identified an XYY syndrome. The technique was previously tested with no false-positive or false-negative results on cultured interphase or metaphase nuclei of fetal fibroblasts and adult T-lymphocytes. Fluorescent in situ hybridization was applied to long-term fixed cytogenetic preparations up to 44 months old and was shown to be reliable.

Amniocentesis↗
PubMed1988

Patients with congenital dopamine beta-hydroxylase deficiency. A lesson in catecholamine physiology.

We recently described a case of congenital dopamine beta-hydroxylase (DBH) deficiency. The syndrome is characterized by noradrenergic denervation, adrenomedullary failure, but intact baroreflex afferents, cholinergic innervation, and adrenocortical function. Norepinephrine, epinephrine, and their degradation products were undetectable in plasma, urine, and cerebrospinal fluid, whereas dopamine and its degradation products were elevated. Plasma DBH was not detectable. Studies in this novel syndrome showed evidence for the peripheral production of dopamine from sympathetic nerve terminals noradrenergic in nature. Tyrosine hydroxylase is probably induced in this syndrome, since plasma levels of L-DOPA were also elevated. Absence of hemodynamic effects of sympathicolytic agents in the face of an increase in blood pressure after dopamine antagonists suggest that intrasynaptic concentrations of dopamine are in the range of its plasma concentrations. Hypoprolactinemia, reduced REM sleep, increased slow wave sleep and sodium loss, despite low blood pressure, are further evidence for the biological role of dopamine in man.

Adult↗
PubMed1988

d,l-threo-3,4-dihydroxyphenylserine restores sympathetic control and cures orthostatic hypotension in dopamine beta-hydroxylase deficiency.

Two patients with congenital dopamine beta-hydroxylase (DBH) deficiency were treated with d,l-threo-3,4-dihydroxyphenylserine (DOPS), 500 mg twice daily. In this orthostatic syndrome the functional integrity of the sympathetic noradrenergic neuron is probably intact, but dopamine instead of noradrenaline is released as the neurotransmitter. In vitro l-DOPS may serve as a substrate for aromatic-l-amino-acid decarboxylase (ALAAD) to form physiological (-)-noradrenaline. During infusion of d,l-threo-DOPS, 400 mg in 4 h, noradrenaline appeared in plasma and blood pressure rose, whereas plasma dopamine and the elevated venous:arterial ratio of plasma dopamine decreased. During chronic treatment supine blood pressure rose from 100-115/55-65 to 140-145/80-85 mmHg and orthostatic hypotension disappeared. After 12 and 6 months of treatment the patients are free of symptoms and they live a normal life. During chronic treatment, d,l-threo-DOPS, like plasma noradrenaline and dopamine, rose after standing, indicating release of the precursor after neuronal stimulation. After administration of tyramine plasma noradrenaline, dopamine and d,l-threo-DOPS and their respective venous:arterial ratios rose; this is further evidence of neuronal release. Thus, in DBH deficiency, dopamine instead of noradrenaline is released as a neurotransmitter, but the integrity of the sympathetic neuron is otherwise intact. Acting as an alternative substrate for ALAAD in the production of noradrenaline, DOPS is taken up by the neuron, restoring sympathetic control and thereby curing the orthostatic hypotension in DBH deficiency.

Blood Pressure↗
PubMed1988

Cardiovascular response to emotional stress and spontaneous blood pressure variability in genetically hypertensive rats of the Lyon strain.

1. Intra-aortic blood pressure (BP) was continuously recorded in freely moving genetically hypertensive (LH), normotensive (LN) and low BP (LL) rats of the Lyon strains under basal conditions and during aversive stimulation (a jet of air for 20 min). Rats were studied when 5 and 14 weeks old. 2. The 24 h standard deviation (i.e., variability) of diastolic BP was significantly greater in LH rats of both ages than in LN and LL control rats. 3. In response to the stressor, LH rats showed larger increases in BP than age-matched controls. 4. The BP variability was related to the BP responses to stress in the whole series of rats. 5. It is concluded that the spontaneous BP variability and the BP responses to an experimental stressor rely upon a common regulatory mechanism in rats and that an increased lability of diastolic BP is a primary characteristic of Lyon hypertensive rats.

Aging↗
PubMed1988

[Influence of hypertension and age on the sympathetic and parasympathetic components of cardiac baroreflex in the conscious rat].

The influence of blood pressure (BP) level and age on the baroreflex sensitivity (BRS) and its autonomic nervous components was studied in genetically hypertensive (LH), normotensive (LN) and low blood pressure (LL) rats of the Lyon strains at 5, 9, 13 and 70 weeks of age. BRS was computed as the slope of the closest relationship, according to the cardiac response delay, between systolic blood pressure (SBP) and heart period changes induced by phenylephrine injections (3 micrograms/kg, i.v.) BRS and the relative importance of vagal and sympathetic components were determined in 4 conditions: 1) basal; 2) after beta-adrenergic blockade (propranolol, 2 mg/kg i.v.); 3) after vagal blockade (atropine, 2 mg/kg i.v.); 4) after vagal and beta-adrenergic blockade (atropine and propranolol, 2 mg/kg, i.v. each). At 5 weeks of age, BRS did not differ between the 3 strains (0.50 +/- 0.05, 0.69 +/- 0.10 and 0.62 +/- 0.09 ms/mmHg in LH, LN and LL rats respectively). In LN rats, BRS increased sharply between 5 and 9 weeks (1.25 +/- 0.12 ms/mmHg) and then remained stable until 70 weeks of age (1.19 +/- 0.14 ms/mmHg). Such an increase did not occur in LH rats and their BRS value was lower than that of LN and LL controls starting from 9 weeks of age. The vagal component of BRS was found to be more important than the sympathetic one in adult rats whatever the strain (80 p. 100 vs 20 p. 100).(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1988

Liquid-chromatographic determination of free and total 3,4-dihydroxyphenylglycol and 3-methoxy-4-hydroxyphenylglycol in urine.

We describe the conjoint measurement in urine of the alcoholic catecholamine metabolites 3,4-dihydroxyphenylglycol (DHPG) and 3-methoxy-4-hydroxyphenylglycol (MHPG). The method involves extraction with ethyl acetate and back-extraction into acetic acid (MHPG), followed by adsorption onto alumina (DHPG). The separation is performed by reversed-phase liquid chromatography with column switching and amperometric detection. Total (free plus conjugated) compounds are determined after a 24-h enzymatic hydrolysis. Twelve-hour excretion values for normal and hypertensive subjects are given, together with results obtained for patients with pheochromocytoma, chemodectoma, and congenital dopamine-beta-hydroxylase deficiency. The assay is sensitive, reproducible, and free of interferences, and may lead to a better understanding of overall catecholamine metabolism in health and disease.

Adrenal Gland Neoplasms↗
PubMed1987

The effects of clonidine and yohimbine on locomotion and cutaneous reflexes in the adult chronic spinal cat.

The effects on the locomotor pattern of a noradrenergic agonist (clonidine) and an antagonist (yohimbine) were studied in 3 adult chronic spinal cats walking on a treadmill. In the early post-transection period, when the cat walked mainly on the tip of its feet, without supporting its own weight, it was observed that clonidine (150 micrograms/kg) could induce a good bilateral foot placement and intermittent complete weight support. When clonidine was given 1-3 months following the transection, at a time when the spinal cats had a stable and regular locomotor performance, the step length increased markedly, especially at low speeds. This was associated with an increase in the duration of the flexor and extensor bursts, as well as an increase of the angular excursion of all joints. These effects, seen during forward locomotion, were also observed during backward locomotion. In addition, the latter was more easily elicited after clonidine. Yohimbine (1.5-3 mg/kg) partially antagonized these effects. The threshold current needed to elicit a small flexion reflex through wires implanted in the dorsum of the paw was 2-3 times higher after clonidine. Trains of shocks in the animal, standing quietly, did not induce the prolonged late discharges normally found in acute spinal cats. Fast paw shaking, elicited by dipping one paw in water, was abolished by clonidine and reappeared after yohimbine. These results indicate that noradrenergic drugs may influence both spinal locomotion and the excitability of cutaneous reflexes. This class of substances could thus play a useful role in the recovery and/or maintenance of locomotor functions after spinal trauma.

Animals↗
PubMed1987

[Circadian changes in the sensitivity of the baroreflex in the conscious rat].

The cardiac baroreflex sensitivity (BRS) was measured in quiet awake rats after phenylephrine injections. It was shown that BRS progressively increased during daytime (rest period) and decreased at the beginning of the night (activity period). These variations were independent from the levels of blood pressure and heart period recorded before the BRS measurements.

Animals↗
PubMed1986

Simple quantitative radioiodination of (E)-5-(2-iodovinyl)-2'-deoxyuridine (IVDU) by exchange labelling.

The synthesis of [125I]-(E)-5-(2-iodovinyl)-2'-deoxyuridine [( 125I]IVDU) by a halogen isotope exchange reaction has been monitored in various reaction conditions. Quantitative incorporation of radioiodine into IVDU was obtained within 20 min by a simple and safe method that is suitable for application in any nuclear medicine laboratory. The radiolabelled antiviral agent can be used without further purification.

Antiviral Agents↗
PubMed1986

Routine analysis of catecholamines and metabolites in urine by a liquid chromatographic column switching system.

A reversed-phase liquid chromatographic technique including a column switching system has been adapted for the routine measurement of catecholamines and their metabolites (14 compounds) in urine. From 1 ml of urine all the compounds and the internal standards were obtained according to combined extraction procedures involving organic solvent, anionic and weakly cationic resins. Finally four extracts (catecholamines, methoxamines, acidic and neutral derivatives) had to be chromatographed throughout a wholly automated apparatus. For each run, the column switching system determined the analytical columns to be used to obtain the separation of the compounds from interferences due to other co-extracted endogenous substances, while the analysis times remained between 20 and 40 min. Such a system allowed the rapid clean-up of columns (in direct- and back-flush mode) carried out between two consecutive injections. By coupling on-line fluorimetric and electrochemical detections the specificity of the technique could be checked, since the ratio of the responses of both detectors was an index of the purity of the peaks. Finally the advanced automation of the equipment allowed weekly the evaluation of catecholamines and the whole range of their known metabolites in 36 urine samples.

Catecholamines↗
PubMed1986

Screening monoclonal antibodies against cell-surface antigens. High frequency of natural antibodies.

Two commonly used methods for screening hybridoma supernatants against cell-surface antigens were performed simultaneously on the supernatant culture fluids of different hybridizations, and compared with the detection of Ig secretion. Supernatants reacting with glutaraldehyde-fixed cells (ELISA (Enzyme-linked immunosorbent assay) on fixed cells) are mostly non-specific for the immunogen; in addition, with this method, only half of the antibodies detected by immunofluorescence are identified. These results can be explained by the frequent occurrence of hybridomas secreting antibodies displaying 'natural antibody' properties, which are strongly reactive with intracellular antigens, and apparently made accessible by the fixation procedure. Since artefacts impair the interpretation of results with ELISA on fixed cells, and complement-mediated cytotoxicity usually as a low yield, membrane immunofluorescence remains the best method for screening hybridoma antibodies.

Animals↗