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Biomedical subjects

F Cesselin

Publications and source records attributed to F Cesselin.

At least 127 records · Page 7Linked to original sources
PubMed1982

Increased levels of Met-enkephalin-like material in the CSF of anaesthetized cats after tooth pulp stimulation.

Tooth pulp stimulation in halothane-anaesthetized cats induced a long lasting (greater than or equal to 3 h) increase in the levels of Met-enkephalin-like material (MELM) in the cisternal CSF. Chromatographic analyses (gel filtration, HPLC) revealed that most of the immunoreactivity was attributable to high molecular weight (mol. wt. greater than or equal to 4000) compounds; in non-stimulated cats, Met-enkephalin (largely in the form of the sulfoxide derivative) only accounted for about 10% of total MELM. In contrast, following tooth pulp stimulation, a large increase in Met-enkephalin (plus Met-Ox5-enkephalin) levels was noted so that the pentapeptide thus represented more than 50% of total MELM. No evidence was obtained for the presence of Met-enkephalin-Arg6-Phe7 in the cisternal CSF of halothane-anaesthetized cats. These data strongly suggest that the activity of enkephalinergic neurons was increased following nociceptive stimulation. This indirectly supports the possible physiological role of enkephalinergic systems in modulating nociceptive inputs.

Animals↗
PubMed1982

Microtopography of methionine-enkephalin, dopamine and noradrenaline in the ventral mesencephalon of human control and Parkinsonian brains.

The topographical distributions of Met-enkephalin, dopamine and noradrenaline were determined in serial frontal sections of human substantia nigra (pars compacta and pars reticulata) and ventral tegmental area. Met-enkephalin was identified by Biogel and thin layer chromatography and assayed by a specific radioimmunoassay. In the substantia nigra (pars compacta and pars reticulata), the levels of Met-enkephalin increased progressively from the rostral to the caudal part of the structure. This pattern closely resembled that of dopamine levels, particularly in the pars compacta. Noradrenaline levels in the substantia nigra and those of Met-enkephalin, dopamine, and noradrenaline in the ventral tegmental area, exhibited only limited fluctuations from the anterior to the posterior part of each structure. Highly significant decreases in Met-enkephalin, dopamine and noradrenaline levels were observed in the substantia nigra and ventral tegmental area of Parkinsonian brains. This observation, together with the close topographical association of dopamine and Met-enkephalin in the substantia nigra, further supports the likely existence of important functional relationships between dopaminergic and enkephalinergic neurons in the human brain.

Aged↗
PubMed1982

Exaggerated prolactin response of thyrotropin-releasing hormone in women with anovulatory cycles: possible role of endogenous estrogens and effect of bromocriptine.

Twenty-one women 18 to 36 years old, presenting with chronic anovulation, were compared with 10 normally cycling women. The patients were characterized by low progesterone (P) levels (0.93 +/- 0.14 ng/ml versus 15.5 +/- 1.4 in controls), whereas 17 beta-estradiol (E2) was moderately decreased (110.2 +/- 8.3 pg/ml versus 162.8 +/- 14.5 in controls) realizing a relative hyperestrogenism. Basal prolactin (PRL) levels were not elevated (12.1 +/- 0.97 ng/ml versus 9.2 +/- 0.7 in controls), but after thyrotropin-releasing hormone (TRH) stimulation an exaggerated response was observed (114.5 +/- 7 ng/ml versus 55.8 +/- 9 in controls). Patients were treated with bromocriptine (1.25 mg 2 times a day) for 3 months. Fifteen responded with ovulatory cycles, and five became pregnant. Progesterone increased significantly (10.2 +/- 1.3 ng/ml), whereas in patients who did not ovulate P increased only slightly (1.56 +/- 0.18 ng/ml). The particular endocrine profile of these patients (P/E2 imbalance) realizing relative hyperestrogenism may be responsible for the exaggerated PRL response to TRH. Bromocriptine, in reducing this transient, or masked, hyperprolactinemia, allows in many patients the return to ovulatory cycles. This mechanism may be one of the possible pathways leading to chronic functional or organic hyperprolactinemia.

Adolescent↗
PubMed1982

Simultaneous measurement of beta-endorphin, lipotrophins and met-enkephalin in phaeochromocytomas.

Tissue concentrations of immunoreactive lipotrophin, beta-endorphin, and met-enkephalin were determined in 10 phaeochromocytomas, 3 of which were responsible for the ectopic ACTH syndrome. Lipotrophin and beta-endorphin immunoreactivities could be detected in all cases, whether or not Cushing's syndrome was present, and their tissue concentrations were significantly correlated (r = 0.95, P less than 0.001). Chromatographic studies showed that gamma-lipotrophin and beta-endorphin were the main peptides in the tumours. Met-enkephalin immunoreactivity was also found in all tumours examined, at much higher concentration and showing no correlation with either lipotrophin or beta-endorphin immunoreactivity. Although beta-endorphin and met-enkephalin are thought to originate from different precursor molecules, these data show that the two opioid peptides may be secreted by the same tumour. The evidence for excess secretion of opioid peptides and their pathological significance in phaeochromocytomas remain to be established.

Adolescent↗
PubMed1982

[Demonstration of enkephalins in pheochromocytoma].

Adrenal medulla has recently been shown to contain high concentrations of enkephalin immunoreactive peptides. In the present study, we report the levels of M-ENK and L-ENK in extracts from 6 cases of human pheochromocytoma. The molecular forms of M-ENK have been characterized by gel filtration chromatography and HPLC. mRNA extracted from one tumor has been proved to code for a 80,000 kilo daltons protein containing M-ENK sequence. M-ENK immunoreactive peptides are secreted in the culture medium of dispersed cultured cells of human pheochromocytoma. This secretion is stimulated when nicotine (10(5) M) is added to the medium. However, the level of plasma M-ENK in pheochromocytoma patients is not significantly different from normal patients. Data from Holaday and al. have established that naloxone (an opiate antagonist) has a beneficial role in shock. But the origin and meaning of plasma M-ENK remain to be established.

Adrenal Gland Neoplasms↗
PubMed1981

Age- and mental health-related circadian rhythms of plasma levels of melatonin, prolactin, luteinizing hormone and follicle-stimulating hormone in man.

Circadian changes in plasma levels of melatonin, prolactin, LH and FSH were studied in four groups: seven healthy young men, six elderly men, six elderly women and six elderly demented patients (two men and four women). The daily activities of the subjects were synchronous and blood samples were taken every 4 h. The 24-h mean concentrations of prolactin in plasma were the same in all groups, whereas those of LH and FSh were twice as high in the elderly as in the young men and eight and 23 times higher respectively in the elderly women. The 24-h mean plasma levels of melatonin in the elderly were half those in the young, but were not influenced by the sex or mental condition of the subjects. A statistically significant circadian rhythm for melatonin was defined in the four groups, for prolactin in all groups except the elderly men and for LH only in the demented patients and in the young men. No circadian rhythm could be detected for FSH in any of the four groups. The acrophases of melatonin and prolactin ranged between 02.30 and 04.00 h, those of LH (when a rhythm was validated) clustered around 01.00 h. The circadian rhythms of plasma levels of melatonin, prolactin and LH are not modified in old age nor in dementia. A positive correlation has been demonstrated in young men between melatonin and LH and between melatonin and prolactin, but no such correlation could be found in the elderly.

Adult↗
PubMed1981

[Angiotensin II and nigostriatal system (author's transl)].

The central renin-angiotensin system is implicated most importantly in the control of water balance, blood pressure and endocrine function (AVP and ACTH). Several central structures are sensitive to angiotensin II (A II), principally: the subfornical organ, the vascular organ of the lamina terminalis, the area postrema and the preoptic area. Furthermore, binding studies with radio-active ligands and also immunohistofluorescence have shown respectively the presence of A II receptors and immunoreactive material bound by A II antibodies in other central structures, and in particular parts of the motor system. In the present study, a double approach, both electrophysiological and biochemical, was used to investigate the possible role of the peptide A II in the neostriatum of the rat. 1 Microiontophoretic application of A II was shown to modify the spontaneous activity of some neurones (15/68) in the neostriatum. Generally, the action of A II was inhibitory and the inhibition was blocked by Sar1-Ileu8-A II, a specific A II antagonist. 2 Angiotensin II 10(-6) M; 10(-5) M; 5.10(-5) M) stimulated the spontaneous release of 3H-dopamine continuously synthetized from 3H-tyrosine in striatal slices of the rat. The A II-evoked release of 3H-dopamine was prevented when slices were superfused with a calcium-free medium containing EGTA. It was also suppressed in the presence of the specific antagonist Sar1-Ileu8-A II. 3 Kainic acid lesion of the intrastriatal cell bodies produced a moderate decrease of A II in the striatum (38%) whilst the activity of the converting enzyme decreased dramatically (-68%). These results suggest that there are angiotensin-containing nerve endings in the neostriatum, and that the cell bodies of such nerves are located outside this structure. Their functional role is discussed.

Angiotensin II↗
PubMed1980

Radioimmunoassay of the myelin basic protein in biological fluids, conditions improving sensitivity and specificity.

The radioimmunoassay (RIA) for myelin basic protein (MBP) in biological fluids was reassessed in order to improve its sensitivity and eliminate some interferences. By using the preincubation technique and the charcoal-dextran-horse serum mixture for the separation step, the detection limit could be lowered to 200 pg/ml for cerebrospinal fluids (CSF), amniotic fluids (AF) and nervous tissue extracts and 600 pg/ml for sera. The RIA could be used directly on CSF, AF and nervous tissue extracts. Sera, however, had to be heated in citrate buffer at 100 degrees C in order to discard interfering material. The present method is 10 to 20 times more sensitive than others previously published. Moreover, it can be applied to amniotic fluid. The biological fluids had to be promptly frozen to avoid degradation of MBP.

Amniotic Fluid↗
PubMed1980

Dopaminergic receptors in human prolactin-secreting adenomas: a quantitative study.

Dopaminergic receptors were observed on the membranes of 26 human PRL-secreting adenomas. Two binding sites were found for [3H]domperidone, a selective dopamine antagonist, with a Kd1 of 0.29 +/- 0.06 nM and a Kd2 of 4.19 +/- 0.7 nM (n = 5). Bmax1 and Bmax2 (maximum numbers of binding sites, first and second sites, respectively) varied from one adenoma to another. When considering Bmax1, two different categories of PRL-secreting adenomas were distinguished, one with a concentration of receptor over 250 fmol/mg protein and others with lower concentrations of receptor (< 250 fmol/mg protein). In the latter, when considering the volume of the tumor, a higher plasma PRL level was found. Two binding sites for [3H]domperidone also were found in the normal human hypophysis with Kd values similar to those of the adenomas (0.18 +/- 0.04 and 3.95 +/- 0.35 nM). The same number of binding sites was observed in normal pituitaries and in PRL-secreting adenomas. However, when considering the density of PRL-secreting cells in the two different tissues (prolactinomas contain 2 or 3 times more PRL-secreting cells than human pituitary tissue), one may suspect a defect in the dopaminergic inhibiting control in PRL-secreting adenomas.

Adenoma↗
PubMed1979

Immunochemical studies of myelin basic protein in shiverer mouse devoid of major dense line of myelin.

The myelin-deficient mutant Shiverer (Shi/Shi) lacks basic protein (MBP) in the myelin of its central nervous system (CNS). Less than 3% of the normal content in MBP is present in a brain extract of Shi/Shi as determined by radioimmunoassay. Indirect immunofluorescence is negative when using specific anti-MBP serum. The importance of Shi/Shi (as compared to other hypomelinating mutants) stems from the specificity of this genetic lesion, i.e. the lack of basic protein.

Animals↗
PubMed1979

In vitro effect of dopamine and L-dopa on prolactin and growth hormone release from human pituitary adenomas.

To determine the site of action of dopaminergic drugs on human PRL and GH release from pituitary adenomas, five PRL-and five GH-secreting adenomas were incubated with and without dopamine and L-dopa. Bromocriptine was also tested in order to compare its effect to that of the other drugs. In all of the experiments except one, a decrease of PRL, which was often statistically significant, was observed. When pooling the results of the PRL-secreting adenomas, the mean levels of PRL with dopamine, L-dopa, and bromocriptine were, respectively, 49%, 55%, and 60% of the control levels. In the GH-secreting adenomas, they were 60%, 67%, and 55% of that of the control. For GH, a decrease of the release was observed in four out of five GH-secreting adenomas. When pooling the results from these tumors, the mean levels of GH with dopamine, L-dopa, and bromocriptine were, respectively, 63%, 76%, and 64% of the control levels. In one case, a significant increase of GH was observed with the three dopaminergic drugs. This study produced the following conclusions. 1) Dopamine acts directly on PRL and GH release from human pituitary adenomas; in vitro, L-dopa effects are similar (its action probably occurs after conversion to catecholamines). These observations strongly suggest the presence of dopaminergic membrane receptors on human lactotroph and somatotroph adenomatous pituitary cells. 2) In vitro hormonal results are in good agreement with in vivo dynamic tests using L-dopa and bromocriptine. 3) The paradoxical effect of dopaminergic drugs on GH secretion in acromegalic patients may be attributed to modified dopamine membrane receptors. However, the paradoxical response is not a constant feature in acromegaly, and its mechanism needs further investigations.

Adenoma↗