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Biomedical subjects

M Mazzuca

Publications and source records attributed to M Mazzuca.

At least 55 records · Page 3Linked to original sources
PubMed1988

Long term treatment with the somatostatin analog SMS 201-995 in a patient with a thyrotropin- and growth hormone-secreting pituitary adenoma.

A patient with a mixed pituitary tumor secreting TSH and GH was treated, starting 3 months after partial adenomectomy, with the somatostatin analog SMS 201-995 for 8 months. Somatostatin itself inhibited TSH, GH, and alpha-subunit release by the tumor both in vivo and in vitro. Long term treatment with twice daily sc injections of SMS 201-995 resulted in decreased TSH secretion and lower serum thyroid hormone levels. However, euthyroidism was achieved only when the patient was treated with three daily 200-micrograms injections of SMS 201-995. After 30 weeks of SMS 201-995 therapy, TSH secretion increased, while GH secretion remained suppressed. After withdrawal for 6 months, SMS 201-995 (100 micrograms, sc, twice daily) again completely inhibited TSH secretion. SMS 201-995 did not alter the volume of the residual adenomatous tissue. We conclude that SMS 201-995 may be a valuable therapeutic agent for the management of patients with a thyrotroph adenoma. However, desensitization may occur during long term treatment.

Adenoma↗
PubMed1987

Fine structural studies of growth-hormone-releasing-factor (GRF)-immunoreactive neurons and their synaptic connections in the guinea pig arcuate nucleus.

The fine structure of neurons containing human growth-hormone-releasing factor (hGRF) immunoreactivity located in the arcuate nucleus of the guinea pig was studied by means of the preembedding immunohistochemical technique. The perikaryon of labeled neurons was fusiform or ovoid; the nucleus was regular in shape and contained a prominent nucleolus. The main ultrastructural features of the hGRF-immunoreactive neurons were the presence of numerous labeled secretory granules (100-120 nm in diameter) and the abundance and the enlargement of the organelles involved in the synthesis of the peptides: a well-developed rough endoplasmic reticulum and a conspicuous Golgi apparatus. Synaptic inputs were observed on immunoreactive perikarya but, above all, on the labeled dendrites. The unstained presynaptic nerve endings most often contained only small clear vesicles and formed symmetrical contacts. In rare cases, the presynaptic terminals exhibited both small clear and large dense vesicles and constituted asymmetrical contacts. Immunoreactive nerve endings were also observed in this area: the synaptic boutons contained large, stained vesicles and small, unlabeled, clear vesicles. These axon terminals made synaptic contacts with unstained dendritic processes; the contacts were symmetrical. The results indicate that hGRF-immunoreactive neurons of the guinea pig arcuate nucleus present morphological features of neuroendocrine cells. Moreover, the presence of hGRF-labeled nerve endings in the arcuate nucleus itself suggests that a substance related to hGRF might be a neuromodulator, at least in this area.

Animals↗
PubMed1987

Ultrastructural demonstration of nerve endings containing a substance related to growth hormone-releasing factor in the guinea-pig paraventricular nucleus.

By means of a preembedding immuno-electron-microscopic technique, a large number of nerve endings containing a substance related to human growth hormone-releasing factor (hGRF) have been demonstrated in the paraventricular nucleus of the guinea pig. They made synaptic contacts primarily with dendritic shafts: 80% of these contacts were symmetrical. The immunoprecipitate was located mainly in large granules and around small clear vesicles. These findings suggest that a peptide related to hGRF may play a role in neural communication in the paraventricular nucleus.

Animals↗
PubMed1985

Treatment of human hyperprolactinaemia with a new dopamine agonist: CU 32085 (mesulergin).

CU 38085 (mesulergin) was given at doses ranging from 0.5 to 5 mg/day to 37 patients with pathological hyperprolactinaemia of varying aetiology. The effectiveness of this drug on the suppression of hyperprolactinaemia and on the recovery of gonadal functions was equivalent to that of bromocriptine previously given to a different group of 83 hyperprolactinaemic patients. Tumour shrinkage during treatment with CU 32085 was ascertained in two cases of macroprolactinoma. Histological examination after adenomectomy revealed extensive peri-vascular fibrosis in both cases. In most patients, the efficient doses of CU 32085 were 5-fold lower than those of bromocriptine. After acute oral administration in 10 previously untreated patients, 0.5 mg of CU 32085 had a more prolonged suppressive effect on Prl levels than 2.5 mg of bromocriptine (approximately 18 vs 12 h). According to this, 0.5 mg CU 32085 once a day was sufficient to maintain Prl levels within the normal range in 16 patients. Side-effects were similar in nature and frequency to those induced by bromocriptine and seemed to be dose-dependent. They can be avoided by slowly increases of dose at initiation of treatment.

Administration, Oral↗
PubMed1984

Accessibility and cross-linking of native neurofilaments to chemical reagents.

Native neurofilaments were submitted to cross-linking reactions with bifunctional reagents (DMA, DMS and DSS) and to chemical reactions with sterically bulky reagents such as EEDQ and DTAF , as well as a glutaraldehyde-activated gel. The 160K and 70K neurofilament proteins reacted slightly more than the 210K neurofilament protein with DMS and DSS. The accessibility of the three neurofilaments to the other chemical reagents was identical. These results were unexpected since neurofilament antibodies seem to react preferentially with 210K protein which is at the periphery of the filament, whereas the 70K protein, which is the backbone of the filament, is probably buried inside the filament. In the same way, it has been shown that the side of the 210K proteins are probably able to cross link the neurofilaments with non covalent and covalent bridges. Using different cross link reagents, we did not observe a characteristic reactivity of the 210K protein towards the different chemicals. We conclude that the three neurofilament proteins are equally exposed to the different sterically bulky reagent and that part of the polypeptide chain of the 70K and the 160K proteins are located at the outside of the filament.

Animals↗
PubMed1983

[Presence of a substance immunologically related to somaliberin extracted from human pancreatic tumor (hpGRF) in neurons of the hypophysiotropic area in the guinea-pig and rat].

An antiserum raised against the synthetic human pancreatic tumour GRF (hpGRF) made it possible to localize an immunoreactive material in 100 nm granules of nerve terminals distributed in the external layer of the median eminence in Guinea-Pig and Rat. Moreover, especially in colchicine-treated Guinea-Pigs, numerous stained perikarya were observed, exclusively located in the arcuate nucleus. These results suggest that hypothalamic GRF is very similar, if not identical, to hpGRF.

Animals↗
PubMed1982

[Dopamine-secreting phaeochromocytoma. A little known clinical and biochemical entity (author's transl)].

The authors have observed a case of phaeochromocytoma revealed by fever and poor general condition without hypertension. Urinary catecholamine assays showed predominant dopamine secretion. Only 13 cases of dopamine-secreting phaeochromocytoma have been published so far, including 4 with clinical symptoms resembling those of this patient. The metabolic and hormonal effects of high plasma dopamine levels were studied, and responses similar to those observed with TRH stimulation by dopamine infusions were obtained: TSH and prolactin responses were inhibited, and GH was increased. This case underlines the need for catecholamine assays, including dopamine, in patients with unexplained fever and apparently non-secretory adrenal tumour.

Adrenal Gland Neoplasms↗
PubMed1982

Use of lectins for detection of glycoconjugates in the glandular cells of the human bronchial mucosa.

Paraffin-embedded human bronchial biopsies, obtained in macroscopically healthy areas, were examined using nine peroxidase-bound lectins. These were either isolated or purified by affinity column chromatography (Ulex europeus, Triticum vulgare, Glycine max, and Arachis hypogatea lectins) or commercial preparations (Lotus tetragonolobus, Canavalia ensiformis, Helix pomatia, Phaseolus vulgaris, and Lens culinaris lectins) and conjugated to peroxidase (except for concanavalin A). These labeled lectins were used as specific molecular probes to localize differences in carbohydrate-containing components present in the different types of glandular cells of human bronchial mucosa. The choice of fixative was crucial and tests used for this study have shown that Carnoy's solution seems to be the most appropriate solution to preserve mucous glycoproteins in situ. Comparison of the affinity of several lectins for human bronchial glycoproteins and for bronchial mucosa demonstrates the predominance of serum-type glycoproteins in serous cells of the submucosal glands and mucin-type glycoproteins in mucous cells of the submucosal glands and in goblet cells of the bronchial epithelium. Furthermore the data obtained with some lectins, such as Helix pomatia agglutinin, suggest that there are some differences in the mucins synthesized by goblet cells and by mucous cells.

Bronchi↗
PubMed1982

[Glucagonoma with diabetic ketoacidosis; case report].

Diabetic ketoacidosis is an extremely rare manifestation of glucagonoma. We report such a case in a 72-year-old woman known to be diabetic for seven years. The patient was admitted with diabetic ketoacidosis and associated necrolytic migratory erythrema which suggested the diagnosis of glucagonoma. Plasma glucagon levels were increased (569 to 2298 pg/ml). A vascular tumor of the head of the pancreas without obvious hepatic metastases was visualised by angiography. Duodeno-pancreatectomy including the head of the pancreas led to complete recovery of the mucocutaneous lesions and the plasma glucagon level fell (229 pg/ml). The tumor had several histological characteristics suggesting malignancy and a high glucagon content on extraction. Electron microscopy showed multiple A cells and a few isolated B cells. Most of the cells showed immunoreactivity with anti-glucagon and anti-glicentine antibodies. Three months after surgery, the diabetes was again required treatment with insulin. Plasma glucagon level was again increased and chemotherapy with dimethyltriazenimidazolecarboxamide was undertaken.

Adenoma, Islet Cell↗
PubMed1979

[Pituitary adenomas with cells containing bêta MSH, alpha and bêta endorphins and without ACTH (author's transl)].

By using immunohistoenzymatic techniques, cells of 4 pituitary adenomas are revealed with beta MSH, alpha and beta endorphins antisera but do not react with 1--24 and 17--39 ACTH antisera. These data suggest that adenomatous cells are able to synthesize and LPH-like molecule without ACTH. The levels of plasmatic LPH and beta MSH, studied by RIA, stay normal. These results are discussed.

Adenoma↗
PubMed1978

[Pituitary adenoma with alpha, 17-39 ACTH and beta, MSH cells, without hypercorticism (author's transl)].

In one case of pituitary basophil adenoma, the majority of the cells contains numerous small granulations which, by using immunohistoenzymatic technique, react with alpha, 17-39 ACTH and beta, MSH antisera. The reaction with anti beta, 1-24 ACTH is negative. The radioimmunoassay of ACTH reveals an increase of plasmatic ACTH, but the cortisol cycle stays low. This data suggests that this functional adenoma releases a product of which has an immunological relationship with ACTH, without biological activity.

Adenoma, Basophil↗
PubMed1977

The prolactin and growth-hormone producing cells of the guinea-pig pituitary. Electron microscopic study using immunocytochemical means.

Different immunohistochemical techniques were used to identify the prolactin and growth hormone producing cells (STH cells) in the pituitary of normal guinea pigs at the ultrastructural level. Prolactin cells revealed two main aspects: 1. Cells with granules from 2500 to 3500 A in diameter some of which are irregularly shaped. These granulations are scattered throughout the whole cytoplasm. The rough endoplasmic reticulum is well developed and organized in parallel lamellae. 2. In cells of the second type the granules are less numerous and smaller in diameter (1800 to 2500 A) and the rough endoplasmic reticulum is less well developed. The cytoplasm of the STH cells contains many more round granules (generally grouped) which also range from 2500 to 3500 A in diameter. The prolactin molecules and the STH molecules are essentially confined to the granules but with the immunocytochemical technique before embedding a slightly diffuse reaction appeared in the entire cytoplasm. These results are discussed.

Animals↗
PubMed1977

Affinity of bronchial secretion glycoproteins and cells of human bronchial mucosa for Ricinus communis lectins.

The coupling of Ricinus communis lectins to Sephadex G 25 was used in order to study mucins and other glycoproteins from human bronchial secretion. The major part of human bronchial mucins and other glycoproteins such as immunoglobulins A, bronchotransferrin and alpha1-antichymotrypsin were isolated by this procedure. A parallel study of human bronchial mucosa was achieved with peroxidase labeled Ricinus communis lectins; this study characterized goblet cells and mucous cells which contain mucins, and serous cells which are involved in the synthesis or the secretion of the other glycoproteins.

Amino Acids↗