Multiple endocrine neoplasia type 2A

A 40-year-old woman was admitted with complaints of headache, palpitation and diaphoresis. She had undergone right hemithyroidectomy 12 years previously. Histological reexamination of the operative specimen revealed a medullary thyroid carcinoma. Abdominal ultrasonography, CT scan and angiography showed bilateral adrenal tumors. Serum catecholamine levels in both adrenal veins were high. Based on these data, bilateral adrenalectomy was performed. Histological examination confirmed the diagnosis of pheochromocytomas. After operation, serum calcitonin and urinary noradrenaline levels were still high. Further examination by 131I-metaiodobenzylguanidine (MIBG) scintigraphy is planned.

Adrenal medullary tumors and iris proliferation in a transgenic mouse model of neurofibromatosis

The expression of the human T-cell lymphotropic virus type 1 (HTLV-1) tax gene in transgenic mice has been shown to result in the development of neurofibromas. Further characterization of these transgenic mice has revealed other significant pathologic similarities between this transgenic mouse model and human neurofibromatosis (NF). Pheochromocytomas of the adrenal medulla and hamartomas of the iris are well-recognized manifestations of human NF. Adrenal medullary tumors have been found in 68% of transgenic animals that were studied. They appear, however, not to be pheochromocytomas, but rather composed of undifferentiated spindle cells. Proliferation of fibroblastlike cells in the iris also occurs in one-half of the transgenic animals surviving more than 6 months. Melanocytes, however, have not been found in the transgenic iris lesion, although they are characteristically found in the Lisch nodules of human NF. The similarities between human neurofibromatosis and this transgenic mouse model (in which the overexpression of a single gene results in neoplasia) are discussed. This transgenic system may provide further insights into molecular mechanisms involved in the pathogenesis of neurofibromatosis.

Diurnal blood pressure variability in mineralocorticoid excess syndrome

Noninvasive 24-h blood pressure (BP) monitoring has demonstrated a diurnal blood pressure profile in most individuals that is characterized by higher arterial pressures during wakefulness and lower pressures at night during sleep. Recently, reports suggest that this typical diurnal variation is absent in syndromes of autonomic dysfunction and in some forms of secondary hypertension. We investigated the 24-h BP, BP variability, and adrenal steroid concentrations in a patient with deoxycorticosterone (DOC)-secreting adrenal adenoma prior to and following adrenalectomy. Preoperatively, when the patient had a ten-fold increase in serum concentrations of DOC, there was no fall in nocturnal BP despite a marked reduction in heart rate during sleep. Postoperatively, when the concentrations of DOC and other adrenal steroids returned to normal values, the 24-h BP profile normalized with restoration of the nocturnal reduction in pressure. These findings document the effects of mineralocorticoid overproduction on diurnal BP regulation. Intensive investigation of individuals with a well-defined etiology of hypertension and the absence of diurnal variation of BP may lead to further hypotheses that will define the role of both autonomic and nonautonomic factors in BP control.

PET scanning with hydroxyephedrine: an approach to the localization of pheochromocytoma

Pheochromocytomas are potentially curable causes of hypertension. These tumors are currently located by functional imaging with meta-iodobenzylguanidine (MIBG), usually labeled with 131I, or anatomic imaging (computed tomography, magnetic resonance). Hydroxyephedrine (HED) is a newly developed radiotracer that concentrates in adrenergic nerve terminals. When HED is labeled with 11C, its distribution can be mapped in vivo using PET. The purposes of this investigation were to characterize the uptake of 11C-HED in pheochromocytoma and to determine the feasibility and advantages of utilizing this compound as a tumor imaging agent. Ten patients with known or suspected pheochromocytoma were studied. Each patient underwent PET scanning with 11C-HED and conventional scintigraphy with MIBG. Pheochromocytomas were localized by PET scanning in 9 of the 10 patients. Image quality was excellent and superior to that obtained from planar and tomographic MIBG studies. The uptake of 11C-HED into pheochromocytomas was rapid; tumors were evident within 5 min following intravenous injection. All lesions within the field of view that were identified by MIBG scintigraphy were readily apparent. PET scanning with 11C-HED localizes pheochromocytoma using a specifically designed radiotracer and advanced imaging technology. The method has promise for locating the more elusive tumors.

Intermediates in the constitutive and regulated secretory pathways released in vitro from semi-intact cells

Regulated secretory cells have two pathways that transport secreted proteins from the Golgi complex to the cell surface. To identify carrier vesicles involved in regulated and constitutive secretion, PC12 pheochromocytoma cells were labeled with [35S]sulfate to identify markers for the two secretory pathways, then mechanically permeabilized and incubated in vitro. Small constitutive secretory vesicles, containing mostly sulfated proteoglycans, accumulated during an in vitro incubation with ATP. In the presence of GTP gamma S, the constitutive vesicles became significantly more dense, suggesting that a coated intermediate was stabilized. Larger immature regulated secretory granules, enriched in sulfated secretogranin II, also escaped from the permeabilized cells in vitro. During granule maturation, their density increased and the amount of cofractionating proteoglycans diminished. The data suggest that sorting continues during secretory granule maturation.

Ultrasonography in the diagnosis of aldosterone-producing adenoma: is it useful?

The usefulness of ultrasonography (US) in the diagnosis of aldosterone-producing adenoma(s) (APA) was compared with computed tomography (CT) and adrenal scintigraphy in 13 patients. The initial examination with US could demonstrate four of seven right APA. Repeat examinations later in two patients whose tumors were initially not detectable did reveal a tumor in one patient. On the other hand, two left APA were delineated on the initial trial. The other seven left APA, except two small APA in one patient, could be delineated during repeat US examinations performed on other days. With CT, all APA were detected during the first or second trial except for the smallest one. The rate of localization by adrenal scintigraphy with dexamethasone pretreatment was 11 of 13 patients. CT had the highest localization rate. However, US was shown to be useful in the localization diagnosis of APA on repeat examinations with a high delineation rate comparable to CT.

Levels of cytochrome P-450, steroidogenesis and microsomal and cytosolic epoxide hydrolases in normal human adrenal tissue and corresponding tumors

The levels of microsomal cytochrome P-450, steroidogenesis and microsomal and cytosolic epoxide hydrolase activities in normal human adrenal tissue (obtained from adult kidney transplant donors and autopsy material) and corresponding hyperplasia, adenomas and carcinomas (surgical biopsies) were determined. The increased steroid production demonstrated by most of the pathological tissue samples examined here was associated with either an unchanged or dramatically decreased specific microsomal content of cytochrome P-450. Furthermore, specific microsomal epoxide hydrolase activity was also found to be reduced in adrenocortical carcinomas, while the corresponding cytosolic activity was also decreased in at least two of these carcinomas. It is of interest to note in this connection that the level of microsomal epoxide hydrolase in slightly atropic adrenal cortex surrounding adrenocortical carcinomas was also found to be reduced. This would indicate that despite its appearance, this surrounding tissue is not normal in all respects. Thus, adrenocortical carcinomas fit into the common pattern in that their specific contents of microsomal cytochrome P-450 are dramatically decreased, but the simultaneous decrease in their microsomal epoxide hydrolase activity is more unusual.

Analysis of uncoupling protein and its mRNA in adipose tissue deposits of adult humans

Brown adipose tissue (BAT) is a specialized adipose tissue whose specific marker is the uncoupling protein (UCP). UCP and its mRNA were previously detected in the perirenal fat of several adult subjects undergoing surgery for pheochromocytoma. We have investigated the possible association of the presence of UCP and its mRNA with pathological conditions other than pheochromocytoma. We obtained adipose tissue from both the periadrenal and the perirenal regions of 36 subjects: group A: human infants (n = 6); group B: adult subjects (n = 11) undergoing surgery for pheochromocytoma; group C: adult subjects (n = 9) undergoing surgery for other endocrine pathologies; group D: adult patients (n = 10) operated for non-endocrine pathologies. In all subjects of group A UCP was detectable by Western analysis. Interestingly, in two newborns, we also found a positive signal for UCP in the peristernal and the retroperitoneal adipose tissues as well as in the perirenal fat. We also identified UCP in eight cases in group B, in five cases in group C and six cases in group D. The human H-UCP-0.5 genomic probe detected a typical BAT mRNA in the periadrenal adipose tissue of all subjects of groups B, C and D showing a positive Western blot. Our results confirm the presence of well-developed BAT in human infants, as well as in adults with pheochromocytoma. They also suggest that human BAT UCP and UCP mRNA are present in adult subjects in pathological conditions other than pheochromocytoma. It might be argued that certain hormones distinct from catecholamine could activate BAT development in human adults.(ABSTRACT TRUNCATED AT 250 WORDS)

Protein phosphorylation regulates secretion of Alzheimer beta/A4 amyloid precursor protein

Extracellular deposition of the beta/A4 amyloid peptide is a characteristic feature of the brain in patients with Alzheimer disease. beta/A4 amyloid is derived from the amyloid precursor protein (APP), an integral membrane protein that exists as three major isoforms (APP695, APP751, and APP770). Secreted forms of APP found in blood plasma and cerebrospinal fluid arise by proteolytic cleavage of APP within the beta/A4 amyloid domain, precluding the possibility of amyloidogenesis for that population of molecules. In the present study, we have demonstrated that treatment of PC12 cells with phorbol ester produces a severalfold increase in secretion of APP695, APP751, and APP770. This increase is augmented by simultaneous treatment with the protein phosphatase inhibitor okadaic acid. These data indicate that protein phosphorylation regulates intra-beta/A4 amyloid cleavage and APP secretion. These and other results suggest that APP molecules can normally follow either of two processing pathways: regulated secretion or proteolytic degradation unassociated with secretion.

[Does hormonal activity of pheochromocytoma affect long-term prognosis in surgically treated patients?]

89 patients were operated upon for pheochromocytoma. 61 patients (37 women and 24 men) were available for follow-up. Mean age at operation was 39 +/- 12.3 yrs. Before operation paroxysmal and sustained hypertension were observed in 34 (55.7%) and 27 (44.3%) patients, respectively. Postoperatively permanent normalization of blood pressure was achieved in 38 cases (62.3%). All patients were divided into four groups. Group I with increased urine excretion of noradrenaline (NA) and adrenaline (A) consisted of 19 (31.1%) patients. Group II (increased NA excretion) included 27 (44.3%) patients. Group III comprised 3 (4.9%) cases with elevated A excretion. 12 (19.7%) patients with normal urinary excretion of catecholamines and increased excretion of methoxycatecholamines were alloted to group IV. Permanent normalization of blood pressure predominantly was observed in group IV--91.6%, whilst in group I, II and III this hypotensive effect was noted in 57.9%, 51.8% and 2/3, respectively. Permanent normalization of blood pressure can be mainly expected in patients with pheochromocytoma in whom catecholamines are rapidly inactivated within the tumor.

A patient with a prolactinoma associated with an aldosterone producing adrenal adenoma: differences in dopaminergic regulation of PRL and aldosterone secretion

A patient with a rare combination of prolactinoma and aldosterone producing adrenal adenoma (APA) was reported in relation to studies concerning dopaminergic regulation of PRL and aldosterone secretion. The patient is a 38-year-old female with plasma PRL and aldosterone concentrations (PAC) of 563 ng/ml and 54 ng/dl, respectively. A bolus of 10 mg of metoclopramide significantly increased plasma PRL in 6 normal subjects and in 4 patients with APA, whereas the responses were blunted in 7 patients with prolactinoma and in our patient. The response of aldosterone to metoclopramide was less than that of PRL, but similar in all studied subjects, indicating that the dopaminergic inhibition of aldosterone secretion is less than that of PRL in normal subjects and did not change in patients with APA or prolactinoma. Oral administration of 2.5 mg of bromocriptine suppressed plasma PRL significantly in all the subjects studied, but did not produce any consistent changes in PAC. Discrepancies in the response of PRL and aldosterone to metoclopramide and to bromocriptine suggest a difference in the dopaminergic regulation of PRL and aldosterone secretion in both normal subjects and patients with prolactinoma and APA. It is unlikely that reduced dopaminergic inhibition is the basis for hypersecretion of PRL and aldosterone in our patient.

Endothelin stimulates aldosterone secretion in vitro from normal adrenocortical tissue, but not adenoma tissue, in primary aldosteronism

In addition to vasoconstriction, endothelin (ET) has been reported to show various endocrine actions in animals. However, no data have emerged concerning the effect of ET on adrenal function in humans. We, therefore, investigated the effects of ET on aldosterone and cortisol secretion from adrenocortical tissues obtained from normal subjects (n = 6) and patients with primary aldosteronism (n = 5). Adrenal tissue slices were incubated at 37 C for 120 min in modified Krebs-Ringer solution containing glucose and HEPES. ET increased aldosterone secretion from normal adrenocortical tissue in a dose-dependent manner, with an ED50 of 0.036 nmol/L, although the maximum response was small compared with that to angiotensin-II. ET also stimulated aldosterone secretion from tissues adjacent to the adenoma, but not from the adenoma, in patients with primary aldosteronism. The effects of ET on aldosterone secretion were significantly suppressed by calcium channel blockade with nicardipine. ET did not affect cortisol secretion from the adrenal tissues. These results suggest that ET is one of the factors that regulates aldosterone secretion in humans.

Botulinum C2 toxin and steroid production in adrenal Y-1 cells: the role of microfilaments in the toxin-induced increase in steroid release

Exposure of adrenal Y-1 cells to C2 toxin results in an increase in steroid release that is accompanied by a rounding of the cell. The actions of C2 toxin mimic those of adrenocorticotropin and cholera toxin except that there is no increase in intracellular cyclic AMP content. In the present study we provide evidence that C2 toxin increases steroid output from Y-1 cells through an alteration in the microfilament network of the cell. C2 toxin significantly increased steroid output after 3 hr of exposure. This effect was accompanied by a significant increase in the transport of [3H]cholesterol to the mitochondrial fraction, independent of cholesterol uptake by the cell. The toxin was unable to increase steroid output from cells prerounded in suspension culture. The protease inhibitors benzamidine and phenylmethylsulfonyl fluoride did not attenuate the ability of C2 toxin to alter the morphology of Y-1 cells. A 3-hr exposure to C2 toxin resulted in the ADP-ribosylation of 50 to 60% of the total actin pool. Fluorescein isothiocyanate-labeled phalloidin visualization of the cytoskeleton of toxin-treated cells confirmed that the toxin caused a decrease in the stress fiber network. C2 toxin treatment of a protein kinase A mutant Y-1 cell (Kin 8) resulted in morphological changes and an increase in steroid output that was not different from that observed for wild type Y-1 cells. The data suggest that C2 toxin increases steroid output from adrenal Y-1 cells by a cyclic AMP-independent mechanism that involves the microfilament network of the cell.

[Pheochromocytoma--basic and clinical analyses]

A variety of vasoactive substances including biogenic amines, neuropeptide Y, somatostatin, enkephalin, ACTH, corticotropin-releasing hormone, growth hormone releasing hormone, vasoactive intestinal peptide, calcitonin, and atrial natriuretic factor have been extracted from intra-adrenal and extra-adrenal pheochromocytomas in men. Some of them appear to play an important role for the development of hypertension or clinical serious symptoms. However, informations on the molecular forms of other substances in pheochromocytomas are still limited, and precise amount of the peptides or hormones in the tumors has not yet been quantitated. Numerous in vitro or in vivo studies of this documented neoplasm over the years have been reviewed in this manuscript. Clinical analyses of early diagnosis, localization diagnosis, treatment of multiple endocrine neoplasia, preoperative and operative treatments are also evaluated in this paper. These informations will probably provide additional evidence for the multi-secretory APUD cells of neural crest origin and will contribute the therapy in patients with pheochromocytoma.

A case of asymptomatic cortisol producing adrenal adenoma

We describe a man without the clinical findings of Cushing's syndrome, but who harbored an incidentally found cortisol-producing adrenal adenoma. On adrenal 131I-adsterol imaging, there was good uptake to the nodule, but no visualization of the contralateral adrenal. No abnormalities were found in the basal plasma cortisol, ACTH, urinary free cortisol and 17OHCS. However, dynamic hormone assessment revealed the existence of abnormal cortisol secretion: no suppression to dexamethasone, incomplete response to human corticotropin-releasing hormone, and lack of diurnal variation in plasma cortisol. Left adrenalectomy was performed with the diagnosis of cortisol-producing adrenal tumor. The pathological finding was an adrenal adenoma, and the perifusion of the excised tissues revealed a negligible response of the tumor tissue to ACTH though the residual normal cortex responded. Postoperative course was uneventful without replacement therapy with cortisol. It is suggested that the tumor autonomously produced a small amount of cortisol not only insufficient to provide clinical Cushing's syndrome, but also to provide typical suppression of hypothalamo-pituitary corticotroph-adrenal system.

The impact of recent advances in diagnostic technology on the clinical presentation of phaeochromocytoma

OBJECTIVE

To examine the impact of recent advances in diagnostic technology on the spectrum of clinical and biochemical features of patients presenting with a new diagnosis of phaeochromocytoma.

DESIGN

A retrospective review of the clinical and biochemical features of patients diagnosed by our laboratory as having phaeochromocytoma within a 27-month period up to December, 1990. Noradrenaline, adrenaline and dihydroxyphenylglycol were assayed in 24-hour urine specimens (19 patients) or plasma (1 anuric patient) by gas chromatography/mass spectrometry.

SETTING

A tertiary level chemical pathology department.

PATIENTS

Twenty patients with a new diagnosis of phaeochromocytoma.

RESULTS

The classic, episodic adrenergic symptoms traditionally associated with phaeochromocytoma were absent in 9 of the 20 patients (45%). "Atypical" phaeochromocytoma presented as a mass on computed tomography imaging (6 patients, 30%), "phaeochromocytoma crisis" (4 patients, 20%) or family screening (1 patient, 5%). Excessive adrenaline production was found in 11 patients (55%) and six (30%) had predominantly adrenaline-secreting tumours. The urinary noradrenaline:dihydroxyphenylglycol ratio was raised in all nine patients with predominantly noradrenaline-secreting tumours but was not raised in nine out of ten patients with adrenaline-secreting phaeochromocytoma. Adrenaline excretion was significantly correlated with tumour size (r = 0.8; P less than 0.05).

CONCLUSIONS

Advances in diagnostic technology, particularly specific adrenaline assays and computed tomography, have made possible the early diagnosis of patients with phaeochromocytoma presenting in ways previously thought to be uncommon. All patients with adrenal masses noted incidentally on CT scan should be investigated for phaeochromocytoma. Adrenaline-secreting tumours are common and both noradrenaline and adrenaline should be assayed in all patients investigated for phaeochromocytoma.

[A case of Cushing's syndrome due to adrenal black adenoma]

Functional black adenoma of the adrenal gland is rare, and there are few reports. We report a case of functional black adenoma of the adrenal gland associated with Cushing's syndrome. The case was in a 59-year-old female, whose chief complaints were weight gain and general fatigue for 7 years. Clinical and laboratory findings were characteristic to those of Cushing's syndrome. With computed tomography and ultrasonography, a round tumor about 18 x 12 mm was detected at the left suprarenal region. Left adrenalectomy was done and a black tumor, 5.0 g in weight, was obtained. Most of the adenoma cells contained numerous pigmented granules which were considered as lipofuscin. The patient is alive without any symptoms of Cushing's syndrome 8 months after the operation. The Japanese literature of the functional black adenoma was also reviewed.

Renin gene expression in the adrenal and kidney of patients with primary aldosteronism

mRNA levels for renin in the adrenal gland and kidney were measured by ribonuclease protection assay (RPA). Renin mRNA was not detected by RPA in aldosteronoma and kidney tissues obtained from two patients with primary aldosteronism (PA). In these patients, the PRA values, plasma concentrations of active renin (ARC), and total renin (TRC = ARC + prorenin) were below the assay limit (less than 0.03 ng/L.s, 2.5 ng/L, and 10 ng/L, respectively). On the other hand, renin mRNA was recognized by RPA in aldosteronoma and kidney tissues obtained from two other patients with PA treated with 50 mg/day spironolactone for more than 2 months. Their TRC values were 49.8 and 16.6 ng/L, but their PRA and ARC were undetectable. Renin mRNA content was greater in normal adrenocortical tissue and in the normal kidneys obtained from three hypertensive patients with renal cell carcinoma. In these patients, the mean values of PRA, ARC, and TRC were 0.28 +/- 0.03 (mean +/- SD) ng/L.s, 18.4 +/- 7.8 ng/L, and 110 +/- 15 ng/L, respectively. This is the first report of the lack of renin gene expression in aldosteronoma and kidney tissues obtained from untreated patients with PA. Furthermore, treatment with spironolactone resulted in an increase in the levels of renin mRNA in the aldosteronoma and kidney tissues of patients with PA.

Pheochromocytoma producing multiple vasoactive peptides

Pheochromocytomas may produce several vasoactive peptides. We studied a 39-year-old man who presented with paroxysmal flushing and abdominal pain with normal blood pressure. Laboratory and radiologic studies established the diagnosis of right adrenal pheochromocytoma, and histologic and ultrastructural examination showed the tumor to be a typical pheochromocytoma. Tissue culture yielded large quantities of norepinephrine and epinephrine. However, immunohistochemical studies, tissue assays, and in vitro cultures documented production of several peptides, including calcitonin gene-related peptide and vasoactive intestinal polypeptide in tumor cells. The patient has been asymptomatic after tumor resection. Production of multiple peptides by this tumor may account for the flushing and lack of hypertension, despite elevated catecholamine levels in this patient.

Adrenal cortex, tumor, and peripheral production of deoxycorticosterone

A method is reported for the measurement of the urine excretion rates of tetrahydro-11-deoxycorticosterone (3 alpha,5 beta-THDOC), an important metabolite of 11-deoxycorticosterone (DOC). Quantification using gas chromatography/mass spectrometry (GC/MS) was achieved by comparing the ion fragment response for the molecular ion (m/z 507) of the analyte (as methyloxime trimethylsilyl ether derivative) to that of a fixed amount of an isomer of THDOC added to urine as internal standard. To improve the specificity of measuring THDOC in clinical samples, an additional Sephadex LH-20 chromatography step was introduced to separate 11-deoxycortisol and some progesterone metabolites. In the luteal phase of the menstrual cycle, THDOC excretion was higher than in the follicular phase; it was also higher than in women taking oral contraceptives. The correlation of THDOC with progesterone production, independent of a constant cortisol output, supports an ovarian or peripheral conversion of progesterone to DOC. The assay proved useful (1) in monitoring for the recurrence of a mineralocorticoid-secreting tumor and (2) when adrenal production of DOC was not fully suppressed in congenital adrenal hyperplasia due to 11 beta-hydroxylase deficiency. Under the latter circumstances, the renin-angiotensin system seemed to be an important regulator of DOC production.

[Incidental disclosure of an adrenal tumor. Diagnostic and therapeutic procedure]

Among upper abdominal computed tomography (CT) scans, 0.6 per 1000 fortuitously reveal an adrenal tumour, an "image pathology" now known as "adrenal incidentaloma". Should the clinician avoid useless, iatrogenic surgery or run the risk of failing to identify a malignant adrenocortical tumour? We outline a clinical procedure aimed at distinguishing between solid vs liquid, secreting vs non-secreting and primary vs metastatic tumour. Nevertheless, in the end the diagnosis may be uncertain, in which case tumour size becomes the deciding factor. For tumours of less than 3 cm close surveillance is advocated, whereas surgery is necessary for tumours larger than 3 cm; for tumours in between these sizes only the individual clinician can decide.

Inhibition of ion channels by hirsutine in rat pheochromocytoma cells

Effects of hirsutine, an alkaloid that produces a potent ganglion blocking effect, were investigated using rat pheochromocytoma PC12 cells. Hirsutine (1 to 10 microM) suppressed dopamine-release evoked by 100 microM nicotine. In voltage-clamped cells, hirsutine (1 to 10 microM) inhibited the inward current activated by 100 microM nicotine. Hirsutine was equipotent to hexamethonium in blocking the nicotine-activated current. The voltage-dependency of the nicotine activated current was not modified by hirsutine. Effects of hirustine on other ion channels were tested to determine its selectivity. Inward currents mediated through ATP-activated channels were scarcely affected by hirsutine (up to 100 microM). However, hirustine (10 microM) inhibited Ba currents passing through Ca channels and K currents activated by depolarizing voltage steps. The results suggest that hirsutine potently blocks nicotinic receptor-channels, but hirsutine also inhibits voltage-gated Ca and K channels. Roles of the inhibition of these channels in the pharmacological effects of hirsutine were discussed.