Diffusion studies in non-oxide ceramics: analytical aspects of the use of ion implanted stable tracers and SIMS.

The physical and chemical properties of complex non-oxide ceramic materials require advanced methods of diffusivity determination. In this study, we present a method based on the high-dose ion implantation of stable tracers in combination with secondary ion mass spectroscopy for depth profiling. The analytical basics, advantages and problems of the method are discussed for two examples of complex materials, the Si-B-C-N precursor ceramics and the Ti-based transition metal diborides. We demonstrate that is possible to measure the temperature dependence of diffusivities, especially for ceramic systems with low diffusivities, for systems that contain elements for which no suitable radioactive tracers exist for extended measurements.

[Pregnancy and hyperprolactinemia. Review of therapeutic measures apropos of a series of 35 patients]. / Grossesse et hyperprolactinémie. Révision des modalités thérapeutiques à propos d'une série de 35 patientes.

Forty-eight pregnancies were observed in 35 patients with hyperprolactinaemia divided into 3 groups according to their initial radiological appearances: normal sella turcica (Group I, n = 11), microadenoma (Group II, n = 12) or macroadenoma without suprasellar expansion, visual defect or pituitary deficiency (Group III, n = 12). Twenty-seven patients were treated with Bromocriptine (Br) from the outs six by adenomectomy + Br, one by adenomectomy alone complicated by meningitis and by corticotropic and thyrotropic hormone deficiencies, followed by amenorrhea despite normalisation of the hyperprolactinaemia requiring induction of a first pregnancy with Clomid. As regards the pregnancies induced by Br (43/48), Br was withdrawn at an early stage in Group I and in the majority of cases in Groups II and III. In all, 37 pregnancies came to term; after Br therapy we observed 5 spontaneous abortions and 3 premature deliveries; 2 caesarian sections were performed before term (one case of hypertension and one adenomatous expansion); one early termination was performed for a tumoral complication. One congenital abnormality (oesophageal atresis) was detected. These observations support the results of extensive studies showing no effects of Br on the outcome of pregnancy and no detectable teratogenic effects with this drug. Five pituitary complications occurred during pregnancy after withdrawal of Br; 1 case of headaches with expansion of a macroadenoma cured by adenometry after prophylactic caesarian section before term; 1 case of optic chiasma compression (Group III) which responded to emergency surgery and 2 cases of pituitary apoplexy (Groups II and III) which responded favourably to Br and in which pregnancy continued normally.(ABSTRACT TRUNCATED AT 250 WORDS)

[Primary hypothalamic tumors (excluding craniopharyngioma). Endocrine and post-radiotherapy development study. Apropos of 17 cases]. / Tumeurs hypothalamiques primitives (en dehors des cranio-pharyngiomes). Etude endocrinienne et évolutive post-radiothérapique. A propos de 17 observations.

The authors underline a number of features of primary hypothalamic tumours (except craniopharyngioma) based on a study of 17 cases: The vital prognosis is satisfactory; only one death was observed with an average follow-up period of 80 months (range 1 to 17 years). This raises the question of the necessity for systematic biopsy to confirm the tumour histology (although when performed in conditions of stereotaxis there are no serious risks). The site of the tumour makes surgery difficult and complete ablation impossible. As many hypothalamic tumours, including the pilocytic astrocytoma which is the commonest type, are sensitive to radiotherapy, this would seem to be the treatment of choice. Total regression is observed in the majority of cases. From the endocrine point of view, the mediocre prognosis is aggravated by high energy radiotherapy. However, with the present therapeutic methods, it is relatively easy to compensate complete or dissociated deficits. There is an endocrine syndrome suggestive of hypothalamic tumour which consists of anterior pituitary deficiency, diabetes insipidus and moderate hyperprolactinaemia (20 to 100 ng/ml). Close medical surveillance is essential, both of the local (visual field and frontal CT scanning) and endocrine effects. Hormonal deficits may occur as a late complication up to 5 years after radiotherapy. The problems inherent to hypothalamic tumours: neurogenic hypernatraemia which is luckily uncommon, with an unexplained weight gain occurring during substitute therapy for adrenal insufficiency with physiological doses of hydrocortisone. Finally, the overall prognosis is good with a minimum of complications due to radiotherapy, excepting endocrine deficiency, providing a dose of 60 grays in 6 weeks at 2 grays per session is not exceeded.

Hyperprolactinemia and estrogen-induced rhythms in LH and prolactin release in the ovariectomized rat.

Short-term (9 days) hyperprolactinemia induced by pituitary grafts reduced basal plasma LH levels in ovariectomized rats whereas long-term (31 days) grafts increased basal LH levels. Although long-term grafts inhibited estradiol-induced prolactin surges, hyperprolactinemia had no effect on the LH surge. It is concluded that the estrogen-treated ovariectomized rat is not suitable for studying the effects of hyperprolactinemia on LH release.

[Results of bromocriptine treatment of giant or invasive prolactin adenomas. Apropos of 20 cases]. / Résultats du traitement par Bromocriptine des adénomes à prolactine géants ou expansifs. A propos de 20 observations.

The therapeutic results of twenty patients with giant expansive prolactinomas were studied under bromocriptine as treatment of first intent (Group I, n = 10) or of second intent after surgery with or without radiotherapy (Group II, n = 10). Patients in Group I (PRL: 350-17 000 ng/ml) were given bromocriptine alone (10 to 20 mg/day) for a period of 21 days to 22 months. The visual fields and acuity returned to normal in 8 days to 3 months in 4 out of 7 patients and significantly improved in 2 out of 7 patients. A reduction in tumour size was demonstrated on CT scanning in 7 out of 10 patients mainly in the suprasellar region (6/9) with appearances of a partially empty sella in 4 cases. Normalisation of the PRL (7 out of 10 cases) was accompanied by a correction of one or more other hypophyseal deficits in 3 patients. Bromocriptine was continued in 5 out of 10 cases with a good result after 12 to 22 months follow-up. Five patients were referred secondarily for surgery for spontaneous rhinorrhea in 1 patient or because Bromocriptine was only partially effective in 4 patients; a postoperative visual improvement with reduced serum prolactin levels was observed in these 4 cases. In Group II (PRL: 200-11 600 ng/ml after surgery), bromocriptine therapy (5 to 30 mg/day for 1.5 to 72 months) was associated with normalisation or a significant improvement in visual symptoms in 6 out of 9 cases and a reduction in tumour size in 8 out of 10 cases.(ABSTRACT TRUNCATED AT 250 WORDS)

Interaction between somatostatin and TRH on growth hormone secretion in perifused human growth hormone tumor cells.

The interaction between somatostatin (SRIF) and thyrotropin-releasing hormone (TRH) on growth hormone (GH) release has been studied on dispersed somatotrophic tumor cells obtained from 7 acromegalic patients. TRH increased GH secretion in 4 cases and SRIF decreased GH secretion in 5 cases. When TRH and SRIF were concomitantly perifused, SRIF, when active by itself, prevented and reversed the TRH-induced stimulation of GH release, while TRH never antagonized the inhibitory effect of SRIF. We conclude that, in these adenomatous cells, the physiological inhibitory factor (SRIF) overcomes the nonphysiological stimulatory factor (TRH) in the control of GH secretion.

[Adrenomyeloneuropathy. Endocrine, clinical and biological study of 4 cases]. / Adrénomyéloneuropathie. Etude endocrinienne, clinique et biologique de quatre observations.

Adrenoleukomyeloneuropathy (ALMN) is a rare neurological and endocrine disorder. It usually affects children, and consists of cortical disease and adrenal insufficiency (adrenoleukodystrophy: ALD). An adult form has recently been identified in which medullary disease is associated with an endocrine disorder (adrenomyeloneuropathy AMN). The authors describe the clinical, biological and physiopathological features of four cases of AMN.

Interaction between estradiol and prolactin on vasoactive intestinal peptide concentrations in the hypothalamus and in the anterior pituitary of the female rat.

To determine whether vasoactive intestinal peptide (VIP) can be regulated by modification of plasma estradiol and prolactin levels, VIP concentrations in various structures of the rat brain and in the pituitary were measured in hyperprolactinemic female rats by means of a specific radioimmunoassay for the peptide. In ovariectomized rats treated with estradiol (E2) implants alone and with both E2 and pituitary grafts to induce an experimental hyperprolactinemia, VIP levels decreased in the anterior and mediobasal hypothalamus and increased in the pituitary as compared to ovariectomized rats. No modification of hypothalamic VIP concentrations was observed in ovariectomized rats with pituitary grafts only, whereas a significant increase was found in the pituitary. These results suggest that, in the female rats, E2 exerts an effect on hypothalamic VIP levels, probably through indirect mechanisms, and that this action can be enhanced by elevated plasma prolactin levels.

Specific binding of [3H]prostaglandin E2 to rat brain membranes and synaptosomes.

There is saturable, reversible and specific binding for [3H]prostaglandin E2 (PGE2) to rat brain membranes. This binding is of high affinity, selectively distributed with a maximum in the hypothalamus, the amygdala and the posterior pituitary, and is associated subcellularly with the synaptosomal fraction. This specific PGE2 binding has the characteristics expected for receptors, so opening new perspectives which might clarify the role of PGs in the brain.