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Biomedical subjects

X Bertagna

Publications and source records attributed to X Bertagna.

At least 109 records · Page 6Linked to original sources
PubMed1988

Plasma pro-opiomelanocortin fragments and adrenal steroids following administration of metyrapone to normal and hirsute women.

The present study was undertaken to characterize further the adrenal abnormalities in the polycystic ovary syndrome (PCOS) and idiopathic hirsutism (IH). We have previously reported the close association of elevated estrone levels with amenorrhea in hyperandrogenemic patients. In addition we have suggested that high estrone levels in PCOS occur as a consequence of the provision of excess substrate, androstenedione, for conversion to estrone. In the present study plasma estrone levels rose following endogenous adrenal stimulation induced using metyrapone; the highest plasma estrone levels achieved were seen in patients with PCOS and occurred later than peak androstenedione levels. These findings are consistent with the hypothesis that elevated estrone levels occurring in PCOS may arise as a consequence of increased adrenal androgen secretion. In addition, we have examined ACTH and other pro-opiomelanocortin (POMC) fragments in an attempt to identify a factor responsible for the excessive adrenal androgen secretion occurring in hirsute patients. Plasma levels of ACTH, and of immunoreactive beta-endorphin and h-lipotropin were not elevated when androgen levels were raised prior to therapy, although these POMC fragments, and also the 16K fragment, rose in response to metyrapone treatment as did androgen levels. Following treatment with dexamethasone there was more profound suppression of the 16K, beta-endorphin and h-lipotropin responses to metyrapone stimulation, than of the ACTH response, as indicated by decreased POMC-fragment/ACTH ratios; this parallels the dissociation of cortisol from androgens in hirsute patients under similar conditions. However, we have not identified a POMC fragment which consistently parallels changes in androgen levels in patients with idiopathic hirsutism or PCOS.

Administration, Oral↗
PubMed1988

Peripheral antiglucocorticoid action of RU 486 in man.

In order to evaluate the peripheral antiglucocorticoid activity of RU 486 in man we examined its ability to antagonize the effects of acutely administered glucocorticoids on blood leukocyte counts. The study was performed on eight normal male subjects. They were given 400 mg RU 486 (or placebo) orally at 0730 h and 1 mg dexamethasone (or placebo) orally at 0830 h, using a double-blind, cross-over, latin-square design with a one week interval between each of the four different treatments. Circulating eosinophils, lymphocytes, and neutrophils were counted at 0730 h and 1330 h, and their variations (1330 h counts/0730 h counts x 100) were compared under each treatment. For each cell type, dexamethasone induced variations (eosinophil and lymphocyte drop, neutrophil rise) which were significantly (P less than 0.05) different from those under the three other treatments; these latter treatments (placebo, RU 486, and RU 486 + dexamethasone) were equivalent to each other, inducing no variations of leucocyte counts. These data show that RU 486 inhibits dexamethasone induced leukocyte changes; this simple test provides a useful means to further analyse the peripheral antiglucocorticoid activity of RU 486 in man.

Adult↗
PubMed1988

Characterization of human corticotrophin-releasing hormone and pro-opiomelanocortin-related peptides in a thymic carcinoid tumour responsible for Cushing's syndrome.

Severe Cushing's syndrome developed in a man of 35 years. Plasma ACTH and lipotrophin hormone levels were supranormal, and dexamethasone failed to stop their production. An ACTH-producing thymic carcinoid tumour was found to be responsible for the Cushing's syndrome. The tumour tissue contained pro-opiomelanocortin (POMC)-mRNA and POMC-related peptides. In addition, human corticotrophin-releasing hormone (h-CRH) (0.25 ng/mg wet tissue) was identified in the tumour extract. Among a series of extracts from two normal and three tumoral (Nelson's syndrome) pituitary glands, six non-pituitary POMC-producing tumours and five normal thymuses examined, only the extract from the thymic tumour of our patient contained h-CRH. The molecule isolated had the same properties as synthetic h-CRH (dilution, Sephadex G 50 chromatography). Circulating h-CRH levels, however, were normal. The possible involvement of such ectopic CRH production in the aetiology of Cushing's syndrome remains uncertain.

Adult↗
PubMed1988

Transsphenoidal pituitary surgery for the treatment of Cushing's disease: results in 64 patients and long term follow-up studies.

Transsphenoidal pituitary surgery was performed in 64 patients with Cushing's disease in search of a corticotroph adenoma. In 4 patients, profuse local bleeding prevented completion of the exploration. Of the 60 patients who had an adequate exploration, 4 could not be followed after surgery. Short term assessment of the surgical outcome (3-6 months postoperatively) was performed on 60 patients, including the 4 who had incomplete pituitary exploration. Forty-two patients (70%) were judged as immediate successes [urinary cortisol excretion, less than 90 micrograms (less than 248 nmol)/day]; the mean urinary cortisol excretion and plasma ACTH level fell from 463 +/- 70 (+/- SE) to 26.7 +/- 3.6 micrograms/day (1277 +/- 193 to 74 +/- 10 nmol/day; n = 33) and from 111 +/- 33 to 36 +/- 14 pg/mL (24 +/- 7 to 8 +/- 3 pmol/L; n = 23) in patients who had both measurements pre- and postoperatively. Eighteen patients (30%) were judged as immediate failures; neither urinary cortisol excretion nor plasma ACTH levels changed significantly in patients who had both measurements pre- and postoperatively. The preoperative epidemiological, clinical, hormonal, and radiological characteristics of the 2 groups were similar. Histological examination of pituitary fragments removed in 58 of the 60 patients evaluated postoperatively revealed the presence of tumoral tissue in a higher percentage of patients in the immediate success group (72%) than in the immediate failure group (24%; P less than 0.01). The 42 patients in the immediate success group were followed from 6 months to 7 yr (median, 2 yr); 6 patients had recurrences from 2-3 yr after operation. Actuarial analysis indicates that the probability of a patient remaining well 6 yr after surgery is 72 +/- 20% (95% confidence limit). Most of the patients in the immediate success group had transient ACTH deficiency preceding a progressive return to normal pituitary-adrenal function.

Adenoma↗
PubMed1988

Human joining peptide: a proopiomelanocortin product secreted as a homodimer.

The human (h) POMC gene sequence predicts a 30 amino acid joining peptide (JP) separating the N-terminal fragment [POMC(1-76) or hNT] and ACTH within their common precursor. We used an anti-serum directed against the amidated COOH-terminal end of mouse JP to develop a RIA for the predicted hJP molecule. Immunoreactive JP was detected in tissue extracts from human normal pituitary, ACTH-secreting pituitary- and nonpituitary tumors, and in plasma from patients with ACTH hypersecretory syndromes. Its molar concentration was of the same order of magnitude as, and correlated with, that of the other POMC peptides. Gel exclusion chromatography in 1% formic acid and 6 M guanidine-HCl revealed a predominant immunoreactive material with an apparent mol wt of ca. 6000. After reduction with dithiothreitol this material was recovered in an elution volume identical to that of purified hJP and corresponding to a mol wt of ca. 3000. These data show that POMC processing generates a COOH terminally amidated hJP predominantly secreted as a homodimer, probably through disulfide bonding between the single Cys9 residue of two molecules.

Chemical Phenomena↗
PubMed1988

[ACTH-secreting tumors. Deregulation of the proopiomelanocortin gene and alterations in processing].

ACTH is produced by proteolysis of a polypeptide precursor, proopiomelanocortin (or POMC). Various POMC-derived peptides are cosecreted with ACTH. Analysis of the ACTH--and its "satellite" peptides--molecular forms establishes the POMC "maturation profile" in different tissues. This profile is identical in normal and tumoral pituitaries (Cushing's disease and/or Nelson's syndrome). It is often altered in non-pituitary tumors responsible for the ectopic ACTH syndrome: abnormal peptides may be generated (CLIP h beta MSH5-22) which can be detected in blood. Analysis of POMC gene transcription in pituitary tumors shows no abnormality. In some non-pituitary tumors the activation of upstream promoters up to 369 nucleotides from the normal (pituitary) transcription initiation site can be shown. In normal non-pituitary tissues a third type of transcription is observed generating a short and probably non-functional messenger RNA limited to a portion of the gene non-coding region.

Adrenal Gland Neoplasms↗
PubMed1988

[Adrenomegaly and other masses of the adrenal area. Diagnostic and therapeutic approaches].

During the 1982-1987 period 104 patients were surgically explored for a mass of the supra renal area. An adrenal tumor was found in 67%, an adrenal pseudo-tumor in 12.5%, a non adrenal pathology in 12.5%, and a tumoral involvement of the adrenal in 8%. Revealing circumstances were variable: 41% of the patients presented with endocrine symptoms (adrenal hypersecretion 83% or deficiency - 17%). In 30% abdominal pain was the chief complaint. In 24% the finding of the adrenal mass was totally fortuitous. In this latter circumstance the diagnostic difficulty is maximal and the strategy remains debated. Our approach would tend to be primarily surgical for fear of letting a malignant tumor evolve further.

Adrenal Gland Diseases↗
PubMed1987

Characterization of proopiomelanocortin transcripts in human nonpituitary tissues.

Proopiomelanocortin (POMC), the precursor to adrenocorticotropic hormone and other related peptides, was originally identified in the corticotropic cell. Recent evidence shows that POMC products are also normally present in a variety of nonpituitary tissues. To investigate this phenomenon in humans we looked for the presence and characteristics of POMC transcripts in various adult tissues. Blot hybridization analysis of normal adrenal, thymus, and testis RNAs revealed a small RNA species approximately 400 nucleotides shorter than the 1200-nucleotide pituitary species. Primer extension and S1 nuclease mapping studies showed that this small RNA lacked exon 1 and exon 2 of the gene, and it corresponded to a set of at least six molecules starting 41 to 162 nucleotides downstream from the 5' end of exon 3. These RNAs appear to result from heterogeneous transcription initiation sites presumably under the control of "GC box" promoter sequences located in the 3' end of intron 2. They cannot encode a complete POMC molecule, and the only truncated POMC molecules that could be translated would lack a signal peptide necessary for membrane translocation and precursor processing. The use of highly sensitive S1 nuclease mapping techniques with uniformly labeled single-stranded DNA probes allowed the detection of a small but definite amount of the "normal," 1200-nucleotide, mRNA species. It is suggested that it is this POMC mRNA that is responsible for the local production of all the POMC peptides.

Adrenal Glands↗
PubMed1986

Human beta-melanocyte-stimulating hormone revisited.

It is generally accepted that human beta-melanocyte-stimulating hormone (h beta MSH) does not normally exist in humans but was merely an artifactually generated 22-amino acid peptide corresponding to a lipotropin (LPH) fragment (residues 35-56). We examined whether the shorter 18-amino acid peptide h beta MSH-(5-22) could be detected in some human tissues. Normal human pituitaries and hypothalami as well as corticotropin-secreting pituitary and nonpituitary tumors were extracted and chromatographed on Sephadex G-50, and the fractions were measured with two radioimmunoassays using either a COOH-terminal human gamma LPH (h gamma LPH) antiserum that recognized equally h gamma LPH, h beta MSH, and h beta MSH-(5-22) or a mid-portion h gamma LPH antiserum that recognized h gamma LPH and h beta MSH but not h beta MSH-(5-22). Normal pituitaries and pituitary tumors contained a single immunoreactive material coeluting with h gamma LPH. The hypothalami and the nonpituitary tumors all contained h gamma LPH and a smaller molecular weight material that was only detected in the COOH-terminal h gamma LPH radioimmunoassay; its elution volume (Ve/V, 0.75) was identical to that of h beta MSH-(5-22) but different from that of h beta MSH (Ve/V, 0.60); on reversed-phase HPLC, it coeluted with synthetic h beta MSH-(5-22) with a retention time different from that of h beta MSH. It is concluded that h beta MSH-(5-22) that corresponds to the 18-amino acid peptide h beta LPH-(39-56), flanked by two pairs of basic amino acids within the h beta LPH molecule, is a normal maturation product of proopiomelanocortin in human nonpituitary tissues.

Amino Acid Sequence↗
PubMed1986

Pituitary-adrenal response to the antiglucocorticoid action of RU 486 in Cushing's syndrome.

RU 486 [17 beta-hydroxy-11 beta-(4-dimethylaminophenyl)17 alpha-(prop-1-ynyl)estra-4,9-dien-3-one] is a steroid analog which antagonizes glucocorticoid action at the receptor level. The pituitary-adrenal response to RU 486 was evaluated in patients with Cushing's syndrome. The acute administration of 400 mg RU 486 at 0800 h in five patients with Cushing's disease induced no significant change in plasma cortisol during the next 10 h compared with the administration of placebo. However, prolonged administration (400 mg daily for 3 days) caused activation of the pituitary-adrenal axis; urinary cortisol increased the most from 727 to 5720, 830 to 8200, 610 to 1020, 110 to 570, and 300 to 990 micrograms/day. Plasma cortisol and lipotropins increased to a lesser extent. Hormone changes appeared on the second day of drug administration and lasted up to 3-4 days after the drug was discontinued. In two patients with nonpituitary-dependent Cushing's syndrome, RU 486 induced no significant change in steroid secretion. We conclude that RU 486 induced a delayed and prolonged pituitary-adrenal response in Cushing's disease; whether the resulting cortisol overproduction will overcome the peripheral effect of RU 486 remains to be determined.

17-Hydroxycorticosteroids↗
PubMed1985

Pro-opiomelanocortin peptides in the human hypothalamus: comparative study between normal subjects and Parkinson patients.

The concentrations of gamma 3-melanotropin-, alpha-melanotropin-, corticotropin-, gamma-lipotropin- and beta-endorphin-immunoreactivities were determined simultaneously, before and after gel exclusion chromatography, in whole hypothalamic extracts of normal subjects and Parkinson patients. All five immunoreactivities were present and were all significantly correlated to each other. Shorter peptides (alpha-melanotropin, gamma 3-melanotropin, beta-endorphin and a lipotropin37-58-like peptide) were the dominant products. Whereas the dopamine content was significantly reduced in Parkinson patients, there was no significant difference for any peptide between normal subjects and Parkinson patients, either in tissue concentrations or in chromatographic patterns.

Adrenocorticotropic Hormone↗
PubMed1985

Altered proopiomelanocortin gene expression in adrenocorticotropin-producing nonpituitary tumors. Comparative studies with corticotropic adenomas and normal pituitaries.

In order to assess the mechanisms of proopiomelanocortin (POMC) gene expression in human ACTH-producing tumors, we performed the simultaneous evaluation of POMC products and messenger RNA (mRNA) in tissue fragments obtained from two corticotropic adenomas, five nonpituitary tumors, and two normal human pituitaries. The POMC products were examined using a combination of gel exclusion chromatography and four different radioimmunoassays directed against gamma 3 melanocyte stimulating hormone (gamma 3MSH), ACTH, gamma-lipotropin (gamma LPH), and beta-endorphin. The POMCmRNA was detected and analyzed by dot and northern blot hybridization using a single-stranded genomic DNA probe corresponding to the coding region of the human POMC gene. Tissue concentrations of POMC products and mRNA showed parallel distributions. Immunoreactive gamma 3MSH and gamma LPH patterns revealed only 16-kD fragment- and gamma LPH-like peptides in normal and tumoral pituitaries; additional gamma 3MSH- and/or beta MSH-like peptides were found in all five nonpituitary tumors. A single POMCmRNA of approximately 1,200 bases (b) was detected in normal and tumoral pituitaries; a single identical POMCmRNA was also found in four nonpituitary tumors. A thymic carcinoid tumor, in addition to the 1,200-b POMCmRNA, contained equal amounts of a second larger POMCmRNA of approximately 1,450 b. It is concluded that POMC gene expression appears qualitatively unaltered in corticotropic adenomas. In nonpituitary tumors, in contrast, abnormal POMC processing is frequent; in addition, an extra POMCmRNA was detected in a thymic tumor with a greater length than the normal mRNA; the mechanisms and pathophysiological implications of these modifications remain to be elucidated.

Adenoma↗
PubMed1984

[Rapid beta 1-24-corticotropin test in the exploration of the corticotropic axis. 71 cases].

The reliability of the beta 1-24 corticotropin test, which is both cheap and safe, in the assessment of the hypothalamic-pituitary-adrenocortical function was re-evaluated by comparing its results with those of the metyrapone test in 71 subjects: 30 controls and 51 patients with suspected pituitary-adrenal dysfunction. Response to a 500 micrograms intramuscular injection of beta 1-24 corticotropin was evaluated by measuring the 60 min plasma cortisol levels; 4.5 g of metyrapone divided into 6 doses were then administered orally and response was evaluated by measuring plasma 11-desoxycortisol levels. A highly significant correlation (r = 0.79; p less than 0.001) was observed between plasma cortisol and plasma 11-desoxycortisol levels. The results were best interpreted by expressing the values obtained as plasma cortisol concentrations which, in normal subjects are at least 21 micrograms/100 ml. The rapid beta 1-24 corticotropin test was found to be very reliable (sensitivity 90%, specificity 100%) to detect adrenal insufficiency, irrespective of the organs affected on the hypothalamic-adrenocortical axis.

Adolescent↗