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Biomedical subjects

G Nicolis

Publications and source records attributed to G Nicolis.

12 recordsLinked to original sources
PubMed1988

Gonadotropin-producing pituitary adenoma in a man with long-standing primary hypogonadism.

Pituitary adenomas that secrete gonadotropins are generally believed to arise spontaneously rather than as a response to chronic primary gonadal failure. However, two women who were found to have gonadotroph adenomas several years after ovarian ablation have been reported. We describe a middle-aged man who developed bitemporal hemianopia and was found to have a large pituitary tumor 35 yr after castration. He had never received any replacement therapy. The tumor was considered to be a primary gonadotroph adenoma, rather than secondary gonadotroph hyperplasia, on the basis of its secretory capabilities, its reticulin patterns, and its specific immunostaining for human FSH beta, human LH beta, and alpha-subunit. Furthermore, the tumor did not decrease appreciably in size after 12 months of testosterone treatment, although plasma gonadotropin levels decreased. Unless the association of primary gonadal failure with a gonadotroph adenoma was coincidental, it suggests that some human gonadotroph adenomas may be secondary to failure of the gonads.

Adenoma↗
PubMed1985

Some further features for differential diagnosis between squamous cell carcinomas and basal cell epitheliomas.

Two further methods for the characterization of epidermal skin tumors are described: the antinuclear antibody (ANA) immunofluorescent test, which consists of indirect immunofluorescence with known high titer sera containing homogenous ANAs on epidermal skin tumors, and the ammoniacal-silver cytochemical method, which specifically stains nuclear histones. Squamous cell carcinomas (SCCs), basal cell epitheliomas (BCEs) as well as control specimens from normal skin and benign epidermal hyperplasias were studied. The ANA immunofluorescent test was positive for most SCCs, mixed SCC and basal cell carcinomas and metatypical BCEs. The ammoniacal-silver method gave a characteristic staining pattern shared among SCCs, mixed carcinomas and metatypical BCEs. BCEs, besides metatypical ones, were always negative by the ANA immunofluorescent test and the same applied for the control specimens. The ammoniacal-silver method gave a characteristic staining pattern for BCEs and control sections quite different from the staining pattern of the more aggressive forms of epidermal tumors. The two methods usually yielded parallel results.

Antibodies, Antinuclear↗
PubMed1976

Sustained oscillations and threshold phenomena in an operon control circuit.

A genetic regulatory model involving a positive feedback (via induction) and a negative feedback (via catabolite repression) is analyzed and applied to the problem of the lac operon regulation in E. coli. Damped and sustained oscillations of the limit cycle type are found along with threshold phenomena corresponding to multiple limit cycles or to multiple steady states, for values of the parameters compatible with experimental data. A comparison with the observations of Knorre and Goodwin is outlined.

Escherichia coli↗
PubMed1975

Pathogenesis of hypertension in Cushing's syndrome.

Steroid production, plasma renin activity (PRA) and plasma renin substrate (PRS) were measured in eight patients with hypertension due to Cushing's syndrome of benign origin. Despite elevation of cortisol secretion in all patients, hypokalemia and suppressed PRA was noted in the one subject with a functioning adrenal adenoma. PRA was normal in six patients on an unrestricted sodium intake but was markedly increased in the two patients on low salt diets. PRS was significantly increased during active disease, but decreased substantially with treatment. The absence of uniform hypokalemia and of suppression of renin indicates that mineralocorticoid production could not account for the increase in arterial pressure. It is suggested that glucocorticoid-induced hypertension may be initiated by alterations in vascular responsiveness to pressor agents and that elevated PRS levels may contribute to increase angiotensin formation.

17-Ketosteroids↗
PubMed1975

Ichthyosis hystrix of 'porcupine man' type. Report of a case.

Ichthyosis hystrix is a term used to describe an ichthyosiform dermatosis in which formation of hyperkeratotic, verrucose excrescences is a prominent clinical feature. This paper deals with an interesting case of ichthosis hystrix associated with a negative family history and two squamous cell epitheliomas.

Adult↗