Showing papers by "Susan M. Webb published in 1992"

Brief report: melatonin-related hypogonadotropic hypogonadism.

Abstract: THE secretion of melatonin from the pineal gland is linked to the light–dark cycle, being greater at night in all species, including humans, and it is pulsatile.1 In humans the peak nocturnal plasma melatonin concentration declines progressively with age, being highest in infants and prepubertal children and lowest in elderly people. Melatonin profoundly influences reproductive function in seasonally breeding mammals. One such species is the Syrian hamster, in which pinealectomy leads to sustained reproductive activity and in which appropriately timed injections of melatonin inhibit reproductive function.2 It is less clear whether melatonin has regulatory actions on the reproductive system in . . .

Computerized tomography versus magnetic resonance imaging: a comparative study in hypothalamic-pituitary and parasellar pathology.

Abstract: OBJECTIVE We wished to analyse the relative value of computerized tomography and magnetic resonance in patients referred for evaluation of pituitary and parasellar lesions. DESIGN We performed a separate evaluation by two independent neuroradiologists of computerized tomography and magnetic resonance images ordered numerically and anonymously, with no clinical data available. PATIENTS We studied 40 patients submitted for hypothalamic-pituitary study; 31 were carried out preoperatively, of which histological confirmation later became available in 14. The remaining nine patients were evaluated post-operatively. MEASUREMENTS Over 40 parameters relating to the bony margins, cavernous sinuses, carotid arteries, optic chiasm, suprasellar cisterns, pituitary, pituitary stalk and extension of the lesion were evaluated. These reports were compared with the initial ones offered when the scans were ordered, and with the final diagnosis. RESULTS Concordance between initial computerized tomography and magnetic resonance was observed in 27 cases (67±5%); among the discordant cases computerized tomography showed the lesion in two, magnetic resonance in 10, while in the remaining case reported to harbour a microadenoma on computerized tomography the differential diagnosis between a true TSH-secreting microadenoma and pituitary resistance to thyroid hormones is still unclear. Both neuroradiologists coincided in their reports in 32 patients (80%); when the initial report was compared with those of the neuroradiologists, concordance was observed with at least one of them in 34 instances (85%). Discordant results were observed principally in microadenomas secreting ACTH or PRL and in delayed puberty. In the eight patients with Cushing's disease (histologically confirmed in six) magnetic resonance was positive in five and computerized tomography in two; the abnormal image correctly identified the side of the lesion at surgery. CONCLUSIONS In patients referred for evaluation of Cushing's syndrome or hyperprolactinaemia (due to microadenomas) or after surgery, magnetic resonance is clearly preferable to computerized tomography. In macroadenomas both scans are equally diagnostic but magnetic resonance offers more information on pituitary morphology and neighbouring structures. Nevertheless, there are cases in which the results of computerized tomography and magnetic resonance will complement each other, since different parameters are analysed with each examination and discordant results are encountered.

Harderian Gland Peptides

Abstract: The description of various peptides in the Harderian glands of different rodents, the rabbit, the cat, and the chicken is recent, dating back only to the early 1980s. Since then, 11 different peptides have been reported in this gland and various hypotheses have been advanced for their function. However, their physiological role in this gland has not yet been defined. This chapter reviews the available information on these peptide substances (Table 1).