Cushing's syndrome associated with ectopic production of corticotrophin-releasing hormone, corticotrophin and vasopressin by a phaeochromocytoma

We describe a case of Cushing's syndrome caused by a phaeochromocytoma secreting corticotrophin-releasing hormone (CRH) and corticotrophin (ACTH). A 49-year-old white woman presented with a 1-month history of lower limb oedema, polydipsia and polyuria. Physical examination revealed a patient with plethoric facies, lanugo-type facial hair, central obesity, red abdominal striae, lower limb oedema, and blood pressure of 210/115 mmHg. Laboratory studies showed high plasma ACTH and markedly elevated urinary cortisol excretion that suppressed more than 50% with high-dose dexamethasone administration. Computed tomographic scan of the abdomen showed a 4-cm left adrenal tumour. Catecholamines and metabolites were markedly increased in a 24-hour urine collection. Results of venous catheterization studies showed that CRH and ACTH were secreted by the tumour. In addition, with ovine CRH administration, inferior petrosal sinus sampling showed pituitary secretion of ACTH. Left adrenalectomy resulted in complete remission of Cushing's syndrome. Light microscopic and immunohistochemical studies revealed a phaeochromocytoma that produced CRH, ACTH and vasopressin. RNA studies showed that this tumour, in contrast to normal adrenal and other reported phaeochromocytomas, transcribed a lone pituitary-sized (1200 nucleotide) pro-opiomelanocortin mRNA. This is the second reported case of a CRH-secreting phaeochromocytoma.

A functional role for vimentin intermediate filaments in the metabolism of lipoprotein-derived cholesterol in human SW-13 cells

Numerous studies have indicated that cytoplasmic intermediate filaments (cIFs) can associate with cellular lipids. To determine if these interactions might have functional consequences, we have studied the lipid metabolism of human SW-13 adrenal tumor cell lines that either contain vimentin-type cIFs (vim+) or lack any detectable cIF network (vim-). Although there were no significant differences in phospholipid or glyceride synthesis, vim- cell lines had elevated levels of cholesterol synthesis and decreased cholesterol esterification, compared with vim+ cells. These differences in cholesterol synthesis and esterification were found to be due to an impaired ability of vim- cells to utilize low density lipoprotein (LDL)-derived cholesterol, although receptor-mediated endocytosis of LDL and the capacity of these cells to esterify endogenously produced cholesterol were not affected. Expression of a mouse vimentin cDNA in stably transfected cell lines, derived from vim- cells, restored the capacity of these cells to utilize LDL cholesterol. The uptake and metabolism of [3H]cholesterol linoleate-loaded LDL showed that the impaired ability of vim- cells to esterify LDL cholesterol was not associated with an accumulation of cellular free cholesterol but rather an increase in the appearance of [3H]cholesterol in the culture medium. These studies indicate that in SW-13 cells, the intracellular movement of LDL-derived cholesterol from the lysosome to the site of esterification is a vimentin-dependent process.

Multiple DNA elements responsible for transcriptional regulation of the ornithine decarboxylase gene by protein kinase A

Transcription of the ornithine decarboxylase (ODC) gene is rapidly elevated by activation of protein kinase A (PKA). The additive influence of three cis-acting elements is responsible for this regulation in an adrenal carcinoma cell line. Two sites, CRE2 at -48 base pairs (bp) relative to the start of transcription and CRE3 at +95 bp, are identical to the core motif of the cAMP-responsive element (CRE) of the somatostatin gene and are conserved in the mouse, rat, and human ODC genes. Mutation of CRE2 resulted in a substantial decrease in basal promoter activity, as well as a 5-fold decrease in inducibility of the ODC promoter by PKA. CRE3 did not contribute to the basal activity of the ODC promoter, but mutation of this site resulted in a 2-fold decrease in inducibility by PKA. Deletion of a 45-bp sequence (GC-box) located 5' of CRE2, also resulted in a 2-fold decrease in inducibility of the ODC promoter. DNase I protection revealed the presence of protein binding at CRE2, the TATA box, and the GC-box of the ODC promoter. Mutation of CRE2 resulted in loss of protection of this sequence, as well as the 3' extension of the footprint over the TATA box, without affecting interactions at the GC box. Antibodies to the well characterized CRE-binding protein CREB recognized proteins binding to CRE2, suggesting that binding of CREB, or an antigenically related protein, is important for the activity of CRE2. Additionally, recombinant CREB bound to a DNA probe containing the CRE2 sequence.

Phaeochromocytomas as a cause of hypotension

A patient presented with apparent septicaemic shock. Full invasive cardiovascular monitoring revealed systemic hypotension, high normal cardiac output, and a low systemic vascular resistance. Maintenance of systemic vascular resistance and blood pressure was shown to be highly dependent on noradrenaline. Subsequent investigation revealed the presence of a phaeochromocytoma producing adrenaline. The mechanisms by which phaeochromocytomas may produce hypotension are discussed.

Preclinical Cushing's syndrome in adrenal "incidentalomas": comparison with adrenal Cushing's syndrome

Adrenal tumors are usually diagnosed by clinical symptoms of hormone excess. The increasing use of ultrasound and computed tomography results in the detection of a substantial number of incidentally discovered adrenal tumors. Most of these tumors are nonfunctional adrenocortical adenomas, but a few cases of subclinical cortisol production in "incidentalomas" have been reported. We investigated prospectively the prevalence of autonomous cortisol production in 68 patients (44 females and 24 males, aged 25-90 yr) with adrenal incidentalomas at our institution. As a screening procedure all patients with incidentalomas underwent an overnight dexamethasone suppression test (1 mg). Patients who failed to suppress serum cortisol below 140 nmol/L (5 micrograms/dL) underwent more comprehensive studies (prolonged dexamethasone suppression test, determination of the diurnal rhythm of cortisol secretion in saliva, and CRH stimulation test). Eight patients (12% of all patients with incidentalomas; 5 females and 3 males, aged 25-71 yr) were finally identified as having cortisol-producing tumors, and the findings in these patients were compared with those of overt Cushing's syndrome in 8 patients (8 females, aged 26-50 yr) suffering from cortisol-producing adrenal adenomas. The tumor size of patients with cortisol-producing incidentalomas ranged from 2-5 cm. No specific signs and symptoms of hypercortisolism were present, but arterial hypertension (seven of eight subjects), diffuse obesity (four of eight subjects), and noninsulin-dependent diabetes mellitus (NIDDM; two of eight subjects) were frequently observed. Baseline cortisol levels were in the normal to upper normal range, whereas baseline ACTH levels were suppressed in five of the eight patients. In none of the patients was serum cortisol suppressible by low dose or high dose dexamethasone. The ACTH and cortisol responses to CRH were normal in two, blunted in one, and suppressed in four patients. Unilateral adrenalectomy was performed in seven patients and resulted in temporary adrenal insufficiency in four of them. After surgery, improvement of arterial hypertension, a permanent weight loss in obese subjects, and a better metabolic control of NIDDM were noted in the majority of patients. The following conclusions were reached. Incidentally diagnosed adrenal tumors with pathological cortisol secretion in otherwise clinically asymptomatic patients are more frequently observed than previously assumed. Adrenocortical insufficiency is a major risk in these patients after adrenalectomy. After surgery, hypertension, obesity, and NIDDM may improve. Patients with asymptomatic adrenal incidentalomas, therefore, should be screened for cortisol production by means of an overnight dexamethasone suppression test.

K-252b selectively potentiates cellular actions and trk tyrosine phosphorylation mediated by neurotrophin-3

K-252b, a protein kinase inhibitor, has been shown earlier to inhibit nerve growth factor actions on cholinergic neurons of the basal forebrain. In the present study, K-252b was found to prevent trophic actions of two other neurotrophins, brain-derived neurotrophic factor, and neurotrophin-3, on central cholinergic and dopaminergic neurons, peripheral sensory neurons, and PC12 pheochromocytoma cells, when used at greater than 2 microM concentration. Comparable actions of nonneurotrophin growth factors were not affected. Surprisingly, at 0.1-100 nM, K-252b selectively enhanced the trophic action of neurotrophin-3 on central cholinergic neurons, peripheral sensory neurons, and PC12 cells. In PC12 cells, K-252b potentiated the neurotrophin-3-induced tyrosine phosphorylation of trk, a protein kinase responsible for transmitting neurotrophin signals. Of the three structurally related nerve growth factor inhibitors, K-252a, K-252b, and staurosporine, only the first two also mediated neurotrophin-3 potentiation. These findings indicate that K-252b generally and selectively potentiates the neurotrophic action of neurotrophin-3 and suggest that this action involves trk-type neurotrophin receptors.

Isoprenylation and carboxylmethylation in small GTP-binding proteins of pheochromocytoma (PC-12) cells

1. A group of 21 to 24-kDa proteins of pheochromocytoma (PC-12) cells was found in blot overlay assays to bind specifically [alpha-32P]GTP. Binding was inhibited by GTP analogues but not by ATP. Such small GTP-binding proteins were found in the cytosolic and in the particulate fraction of the cells, but they were unevenly distributed: about 75% of the small GTP-binding proteins were localized within the particulate fraction of the cells. Separation of these proteins by two-dimensional gel electrophoresis revealed the existence of seven distinct [alpha-32P]GTP-binding proteins. 2. Targeting of the small GTP-binding proteins to the particulate fraction of PC-12 cells requires modification by isoprenoids, since depleting the cells of the isoprenoid precursor mevalonic acid (MVA) by the use of lovastatin resulted in a 50% decrease in membrane-bound small GTP-binding proteins, with a proportionate increase in the cytosolic form. This blocking effect of lovastatin was reversed by exogenously added MVA. 3. In addition, metabolic labeling of PC-12 cells with [3H]MVA revealed incorporation of [3H]MVA metabolites into the cluster of 21 to 24-kDa proteins in a form typical of isoprenoids; the label was not removed from the proteins by hydroxylamine, and labeling was enhanced in cells incubated with lovastatin. The latter effect reflects a decrease in the isotopic dilution of the exogenously added [3H]MVA, as the addition of exogenous MVA reversed the effect of lovastatin on [3H]MVA-metabolite incorporation into the 21 to 24-kDa proteins. 4. Additional experiments demonstrated that isoprenylation is required not only for membrane association of small GTP-binding proteins, but also for their further modification by a methylation enzyme. This was evident in experiments in which the cells were metabolically labeled with [methyl-3H]methionine, a methylation precursor. The group of 21 to 24-kDa proteins was labeled with a methyl-3H group in a form typical of C-terminal-cysteinyl carboxylmethyl esters. Their methylation was blocked by the methylation inhibitors methylthioadenosine (MTA), 3-deazadenosine and homocysteine thiolactone as well as by lovastatin. MVA reversed the lovastatin block of methylation. 5. Two-dimensional gel analysis of the [3H]methylated proteins detected seven methylated small GTP-binding proteins that correspond to the isoprenylated proteins. Levels of the small GTP-binding proteins as well as isoprenylation and methylation were reduced by cycloheximide. 6. Distribution of the methylated proteins between particulate and cytosolic fractions was found to be similar to that of the small GTP-binding proteins (i.e., a 4:1 ratio).(ABSTRACT TRUNCATED AT 400 WORDS)

Production of immunoreactive corticotropin-releasing hormone in various neuroendocrine tumors

The concentrations of immunoreactive (IR) corticotropin-releasing hormone (CRH) in 218 neuroendocrine tumors were determined by CRH radioimmunoassay. The tumors examined were 86 pancreatic endocrine tumors (PET), 22 neuroblastic tumors (NBT), 26 carcinoid tumors (CA), 24 pheochromocytomas (PHEO), 40 small cell lung carcinomas (SCLC) and 20 medullary thyroid carcinomas (MTC). IR-CRH was detectable in 21 neuroendocrine tumors (10 PET, four NBT, three CA, two PHEO and two SCLC) at levels of 10-2,700 ng/g wet weight (9.6%). The 21 patients with these CRH-producing tumors showed no clinical symptoms suggestive of Cushing's syndrome. The levels of plasma IR-CRH extracted by immunoaffinity chromatography were < 7.5 pg/ml in five normal subjects and a patient with a neuroblastic tumor containing 55 ng/g wet weight IR-CRH, but in a patient with a thymic carcinoid tumor containing 1,000 ng/g wet weight IR-CRH, the plasma level was elevated to 180 pg/ml. This patient did not have Cushing's syndrome nor an elevated plasma adrenocorticotropic hormone (ACTH) level. The concentrations of nine peptides (growth hormone-releasing hormone, somatostatin, ACTH, calcitonin, gastrin-releasing peptide, glucagon, vasoactive intestinal peptide, neuropeptide tyrosine and pancreatic polypeptide) were determined in extracts of the 21 IR-CRH-producing tumors. Some of these peptides were frequently found to be produced concomitantly with CRH. The results indicate IR-CRH to be produced by various neuroendocrine tumors, but Cushing's syndrome, due to the CRH, to be very rare. The results also show that CRH-producing tumors produce multiple hormones.

Aldosterone-secreting adrenal adenoma as part of multiple endocrine neoplasia type 1 (MEN1): loss of heterozygosity for polymorphic chromosome 11 deoxyribonucleic acid markers, including the MEN1 locus

A 63-year-old female presented with the extremely rare occurrence of an aldosterone-secreting adrenocortical adenoma as part of the syndrome of multiple endocrine neoplasia type 1 (MEN1). Only two other MEN1 patients were reported in the literature with hyperaldosteronism. The patient's MEN1 syndrome consisted of the association of primary hyperparathyroidism due to parathyroid adenoma, a prolactinoma, and a toxic multinodular goiter. Elevated basal and meal-stimulated serum PP levels without demonstrable pancreatic tumor were also found. Genetic analysis of the aldosterone-secreting adenoma with DNA markers localized on chromosome 11 showed loss of heterozygosity in tumor DNA. Since the MEN1 syndrome is caused by loss of the tumor suppressor gene on chromosome 11 in the 11q13 region, it is probable that the same mechanism is associated with the formation of the adrenocortical adenoma.

[Does the captopril test improve the diagnosis of primary hyperaldosteronism?]

Plasma concentrations of renin and aldosterone were measured before and 60 min after taking 25 mg captopril in 242 patients with arterial hypertension (124 men, 118 women, aged 51.9 +/- 12.7 years; unilateral aldosterone-producing adrenal adenoma in 8, idiopathic hyperaldosteronism in 16 and essential hypertension in 189). Basal plasma aldosterone levels were twice as high in those with adenoma or hyperaldosteronism (216.9 +/- 99.1 pg/ml and 256 +/- 123 pg/ml, respectively) as in those with essential hypertension (117.7 +/- 115 pg/ml). Basal renin levels in adenoma and idiopathic hyperaldosteronism (1 +/- 0.8 microU/ml and 2.6 +/- 1.9 microU/ml, respectively) were decreased compared with those in essential hypertension (13.1 +/- 14.2 microU/ml). The basal aldosterone/renin ratio was higher in adenoma (436 +/- 370 pg/microU) and idiopathic hyperaldosteronism (615 +/- 950 pg/microU) than in essential hypertension (52.9 +/- 151.3 pg/microU). The sensitivity of this ratio in combination with the aldosterone concentration was 100% for recognizing an adrenal adenoma, its specificity 92.7%. The mean plasma aldosterone level after captopril administration did not change in adenoma patients, but fell to 162 +/- 85 pg/ml (P less than 0.001) in those with idiopathic hyperaldosteronism. These data indicate that the captopril test contributes to distinguishing primary from idiopathic hyperaldosteronism.

Plasma aldosterone response to upright posture and angiotensin II infusion in aldosterone-producing adenoma

Nineteen patients with primary aldosteronism due to surgically confirmed aldosterone-producing adenoma (APA) were examined to evaluate the response of aldosterone to upright posture and angiotensin II infusion. Upright posture reportedly decreases the plasma aldosterone concentration (PAC) in APA but raises it in idiopathic hyperaldosteronism. However, our findings showed the opposite result, in that the upright posture did not change or raised PAC in 15 of 19 cases (79%). Angiotensin II was infused i.v. at doses from 0.5-2 ng/min.kg body weight in six patients in whom the upright posture raised PAC, but did not raise PAC in all cases. This result supports the assumption that APA is functionally insensitive to angiotensin II. A concomitant rise of ACTH, pretreatment with calcium channel blockade, and other modulating factors may be involved in this PAC rise. Whatever the reason, such a high frequency of patients with increased PAC in APA raises some question about the clinical value of the upright posture test. We believe, then, there is reason to check any interpretation concerning increased PAC in the case of the upright posture test in distinguishing between APA and idiopathic hyperaldosteronism.

Urodynamics in patients with pheochromocytoma: a peri-operative study of 10 cases

Alpha receptors have been demonstrated in the bladder neck, and urinary retention may be the presenting symptom in an occasional pheochromocytoma patient. This prompted us to define the urodynamic profile in pheochromocytoma patients. Ten patients were studied. Except for 2 patients, all tumors secreted norepinephrine either alone (n = 4) or mixed (n = 4). Urodynamic studies (uroflowmetry, cystometry, profilometry, response to alpha-adrenergic agents) were performed with Urodyn 5000 chain (DANTEC) connected to a water perfused Bohler's catheter. Profilometry was done according to the Brown and Wickham technique. Normal values were those of the International Continence Society. Alpha blocker test was done by intravenous injection of thymoxamine (0.5 mg/kg) and was considered as positive if urethral closure pressure (UCP) decrease was greater than 30% after 10 minutes. Ten patients had a pre-operative study, omitting alpha-blocker test in 1 patient; 5 patients consented a postoperative study. Pre-operatively we could demonstrate: 1) Increased UCP in 8 of 10 patients, regardless of the secretory pattern; 2) Response to alpha-adrenolytic agents in 7 of 9 patients; and postoperatively: 3) Good correlation between a positive alpha-blocker test and a decrease in urethral pressure in 3 of 5 patients. Urodynamics in pheochromocytoma patients show a typical alpha-adrenergic pattern and may explain bladder dysfunction as a presenting symptom.

Isolation of peptides arising from the specific posttranslational processing of chromogranin A and chromogranin B from human pheochromocytoma tissue

An extract of human adrenal medullary pheochromocytoma tissue was fractionated by gel permeation chromatography, and peptides of major abundance in the approximate molecular mass range 1000-4000 were purified to apparent homogeneity by reverse phase HPLC. Determination of the primary structures of four such peptides demonstrated that they were fragments of either chromogranin A or chromogranin B. The peptide WSKMDQLAKELTAE represents chromogranin A(324-337), the peptide LGELFNPYYDPLQWKSSHFE represents chromogranin B(498-517), the peptide NLARVPKLDL represents chromogranin B(568-577), and the peptide QYDRVAQLDQLLHY (isolated as the N-terminal pyroglutamyl derivative) represents chromogranin B(580-593). Analysis of the nucleotide sequences of cDNAs complementary to human chromogranin A and B messenger RNAs indicates that each of these peptide sequences is flanked by pairs or groups of basic residues, suggesting that these fragments are the products of specific posttranslational processing. In addition, a peptide identified as chromogranin B(496-517) was isolated from extract. This component represents the product of incomplete proteolytic cleavage at the Lys494-Arg495-Lys496-Arg497 processing site in chromogranin B. A minor component in the extract was identified as chromogranin B(508-517), but this component probably represents an artifact of the extraction procedure arising from the hydrolysis of the acid labile Asp507-Pro508 bond. The study has shown that chromogranin A and B in pheochromocytoma tissue function as the precursors of several small peptides that may have a regulatory role.

Xanthofibroma of the adrenal gland

The authors report on a 43-year-old woman who had undergone unilateral adrenalectomy for a right suprarenal mass. The removed specimen was histopathologically defined as xanthofibroma, a hitherto unpublished adrenal tumour. The connective tissue protein of this rare tumour contained great amounts of collagen, non-collagenous protein and elastin. The significance of such abnormal proliferation of fibrous tissue and the conventional sonographic and CT features of this neoplasm are discussed.

Identification of inositol 1,4,5-trisphosphate binding in human pheochromocytoma

An attempt was made to identify a specific binding of inositol 1,4,5-trisphosphate (IP3) to human chromaffin cell tumors. Crude microsomal fractions of pheochromocytomas possessed significant binding sites for [3H]IP3 with high- and low-affinity constants (Kd = 5.46 and 538 nM, respectively). The binding to these sites was rapid, saturable (reached equilibrium by 1 min at 0 degrees C) and reversible. Competition studies with other inositol phosphate analogs indicated the stereotypic specific binding for IP3. Although no significant difference was observed in the binding densities of IP3 between pheochromocytomas and adrenal nonfunctioning adenomas, the values of high-affinity constants were significantly lower in the former than the latter group (5.77 +/- 1.07, n = 5 vs. 11.30 +/- 1.98 nM, n = 4, p less than 0.05). The present data indicate that characteristics of IP3 binding sites are congruous with their receptor functions and that changes in its binding sites may contribute to the biochemical dissimilitudes in pheochromocytomas.

The role of epinephrine, norepinephrine, and dopamine in blood pressure disturbances in patients with pheochromocytoma

Fifty-six patients with pheochromocytoma underwent surgery during the 9-year period from 1981 to 1990. These patients were divided into two groups according to whether the dominant plasma concentration was of epinephrine or norepinephrine. Plasma levels of the catecholamines were stratified into three grades at 5 and 10 times the normal upper limit. Pre-operative disturbances of blood pressure, sustained or paroxysmal, and normal blood pressure were highly correlated with the dominantly secreted catecholamine and its plasma concentration. Thirteen patients with high plasma norepinephrine levels (greater than or equal to 10 times normal) had sustained hypertension while 18 patients with moderate to high plasma epinephrine levels (greater than or equal to 5 times normal) had paroxysmal hypertension. In the majority of normotensive patients (12 of 14), plasma catecholamine levels were less than 10 times the upper normal limit. Urinary excretion of dopamine and size of the tumor were analyzed according to these patient groups. In the norepinephrine dominant group, urinary dopamine excretion tended to be proportional to the plasma epinephrine levels and when the patients were normotensive, urinary dopamine excretion decreased. In norepinephrine-secreting patients, urinary dopamine tended to be inversely correlated with the plasma norepinephrine level; however dopamine did not prevent the hypertensive action of norepinephrine. Tumor size showed no correlation with the plasma levels of catecholamine in the moderate to high plasma catecholamine groups. We conclude that the plasma catecholamine type and its level are the most important factors in determining the patterns of blood pressure disturbances of patients with pheochromocytoma.

[Forty-one cases of Cushing's syndrome: a comparison between Cushing's syndrome (adrenal adenoma) and Cushing's disease (adrenal hyperplasia)]

We experienced 41 cases of Cushing's syndrome (12 males and 29 females, 15 years old - 65 years old) during the last 20 years. These included 20 patients with unilateral adrenal adenoma (Cushing's syndrome), 19 patients with bilateral adrenal hyperplasia (Cushing's disease), one patient with adrenal carcinoma and one patient with primary adrenocortical nodular dysplasia (PAND). Moreover, these cases included some special ones, i.e. 5 cases with destructive thyroiditis after treatment, 2 cases with aggravation of arthritis after treatment, a case of Carney's complex with PAND, one case with paradoxical response to dexamethasone, and one case combined with empty sella syndrome. The most specific clinical signs were moon face (95% occurrence), hypertension (95%) and subcutaneous bruising (80%). Other significant signs were eye edema (66%), buffalo hump (68%), subcutaneous purpura (63%) and osteoporosis (49%). Skin striae was not a common sign in our cases (41%). Renal stone was observed in only 20% of our patients but was a significant sign in this syndrome. There was no difference in the occurrence of each clinical sign between Cushing's syndrome and Cushing's disease. The elevation of white blood cell count (WBC) and serum sodium, a decrease of serum potassium, and a decrease of reabsorption of phosphate (%TRP) were observed. Thyroid-stimulating hormone (TSH) and human growth hormone (HGH) were suppressed in patients with Cushing's syndrome and patients with Cushing's disease. These results were consistent with those of previous reports. However, luteinizing hormone (LH), follicle-stimulating hormone (FSH) and prolactin (PRL) were high in those patients with Cushing's syndrome and those with Cushing's disease. Oral glucose tolerance test was carried out in 34 patients before and after treatment. Thirty-one percent of those had diabetes mellitus and 26% had impaired glucose tolerance (IGT). The response of IRI in this test was high in patients with Cushing's syndrome and patients with Cushing's disease, and decreased 4 weeks after treatment in those with Cushing's syndrome but remained high in those with Cushing's disease. Plasma ACTH level and urinary 17-OHCS excretion were significantly higher in Cushing's disease than in Cushing's syndrome. During an 8mg-high-dose dexamethasone suppression test, urinary 17-OHCS excretion in 13 of 14 patients with Cushing's disease (93%) was suppressed by more than 50% of baseline on the second day of testing. However, all of 18 patients with Cushing's syndrome, who had an 8mg-dexamethasone suppression test, failed to suppress urinary 17-OHCS by 50% of baseline.(ABSTRACT TRUNCATED AT 400 WORDS)

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.