Showing papers by "Susan M. Webb published in 1996"

Thirty years of human pineal research: Do we know its clinical relevance?

Abstract: A role for melatonin in humans is becoming evident in an increasing number of clinical situations Marked variations in the magnitude of the nocturnal melatonin peak are observed throughout the human lifespan The highest levels occur in children and then fall during puberty and further during adulthood A negative correlation between circulating melatonin and sex steroids has been observed in a number of instances, and appears to be independent of concomitant gonadotrophins No clear melatonin pattern has been observed in pituitary tumors, but in large lesions that involve the hypothalamus, a reduced nocturnal rise has been reported Reported effects of exogenously administered melatonin are variable, probably reflecting differences in dose and timing; a slight stimulation of prolactin, as well as a partial inhibition of gonadotrophins, has been reported, which explains its utility as an oral contraceptive, associated with a progestogen A potential clinical use of melatonin as an oncostatic drug still awaits confirmation, although experimental data firmly support this possibility The indole has also been used to hasten entrainment of subjects travelling across various time zones, and has been found to be specially useful in eastward travel Finally, changes in the normal melatonin circadian pattern have been reported in psychiatric diseases and in sudden infant death syndrome

Flow Cytometry Analysis of Pituitary Adenomas

Abstract: Using flow cytometry, DNA content and index, and/or proliferative capacity (measuring proliferating cell nuclear antigen PCNA) in operated pituitary tumors, control pituitaries obtained at necropsy, and experimental pituitary hyperplasia induced in rats were analyzed Simultaneous measurement of cell ploidy and proliferation differentiated normal pituitary (diploid DNA index and negative PCNA) from pituitary hyperplasia (diploid DNA index with intensely positive PCNA, between 30 and 72% of cells) In the tumors 83% (19/ 23) were positive for PCNA (between 3 and 84%) and 73% (17/23) aneuploid; only 1 tumor was diploid and negative for PCNA Conclusions: Differentiation between normal and abnormal (neoplastic or hyperplastic) pituitary is possible by flow cytometry, but in the adenomas no correlation with postoperative clinical outcome was observed

Expression of the somatostatin gene and receptors in the rat harderian gland

Abstract: Somatostatin is one of the numerous peptides described in the Harderian gland of different animals. With the aim of trying to elucidate its physiological role, we investigated whether this peptide is expressed in OFA rat Harderian gland at different ages and seasons and, if so, studied the regulatory proteins involved in the activation of the somatostatin gene, and also whether it contains any somatostatin receptors. Nursing (4-15-day-old), prepubertal (21-30-day-old), and adult (54-day-old) OFA rats were sacrificed by decapitation throughout the year, and the Harderian glands were excised and immediately frozen in liquid N2. The expression of somatostatin and its receptors was investigated using RT-PCR techniques; additionally, the existence of proteins which bind to cAMP responsive elements (CRE) was investigated using a band-shift technique. The somatostatin gene was expressed in the Harderian gland of rats aged 4-30 days in autumn and winter but not in spring and summer or in older animals. However, the somatostatin receptor was expressed throughout the year at all the ages studied. In the autumn, nuclear proteins binding to CRE (CREB) were present in 8-10-day-old rats but not in younger 4-day-old animals. We conclude that rat Harderian gland cells transcribe the somatostatin gene depending on the season and age of the animals, while its receptor is always present at all the ages studied; the CREB found produces the same retardation complex as ICER (inducible cAMP early repressor), an isoform of CREM (cAMP responsive element modulator), which in the pineal has been shown to be under adrenergic control. Since somatostatin expression is regulated by cAMP mechanisms, it is feasible that the existence of this repressor ICER could explain why somatostatin expression disappears in adult animals once maturation is complete.

Bronchial carcinoid tumor presenting as a thyroid nodule: an unusual clinical manifestation.

Abstract: Although rare, carcinoid tumors may present as thyroid metastatic nodules. We describe two patients with an undiagnosed bronchial carcinoid tumor, who presented as a thyroid nodule. Pathological examination of these nodules was diagnostic. Chemotherapy was indicated despite the dissemination of the tumors. The patients have an excellent quality of life. They are asymptomatic and alive, 18 and 24 months after diagnosis, respectively. In one case, chemotherapy obtained an important reduction in the size of the tumoral lesions but the other case showed no regression. Octreotide (SMS 201-995) was used in the case with carcinoid syndrome, with an excellent response.