Enfoque diagnóstico de feocromocitomas y paragangliomas / Diagnostic approach of pheochromocytomas and paragangliomas

Los feocromocitomas y paragangliomas son tumores neuroendócrinos poco frecuentes y con alta morbimortalidad. Reconocer las distintas formas de presentación es el paso diagnóstico inicial. El estudio bioquímico permite determinar el exceso de catecolaminas y sus metabolitos. Sin embargo, las determinaciones disponibles ofrecen diferente precisión diagnóstica. La tomografía computada y la resonancia magnética permiten localizar estos tumores con una alta sensibilidad. Los estudios funcionales se reservan para sospecha de enfermedad metastásica y para tumores múltiples. Un tercio de los pacientes presenta una mutación genética germinal y varios genes están implicados en el desarrollo de estos tumores

Pheochromocytomas and paragangliomas are rare neuroendocrine tumours associated with high morbidity and mortality. Recognizing the clinical presentation is the first step for diagnosis. Biochemical studies may determine an excess of catecholamines and their metabolites. However, the available tests offer varying diagnosis precision. Computed tomography and magnetic resonance are highly sensitive for locating these tumours. Functional tests are reserved for when metastatic and multifocal disease are suspected. One third of the patients have a germline mutation and many genes are involved in the development of these tumours

[Diagnostic approach of pheochromocytomas and paragangliomas]. / Enfoque diagnóstico de feocromocitomas y paragangliomas.

Pheochromocytomas and paragangliomas are rare neuroendocrine tumours associated with high morbidity and mortality. Recognizing the clinical presentation is the first step for diagnosis. Biochemical studies may determine an excess of catecholamines and their metabolites. However, the available tests offer varying diagnosis precision. Computed tomography and magnetic resonance are highly sensitive for locating these tumours. Functional tests are reserved for when metastatic and multifocal disease are suspected. One third of the patients have a germline mutation and many genes are involved in the development of these tumours.

RSUME inhibits VHL and regulates its tumor suppressor function.

Somatic mutations or loss of von Hippel-Lindau (pVHL) happen in the majority of VHL disease tumors, which present a constitutively active Hypoxia Inducible Factor (HIF), essential for tumor growth. Recently described mechanisms for pVHL modulation shed light on the open question of the HIF/pVHL pathway regulation. The aim of the present study was to determine the molecular mechanism by which RSUME stabilizes HIFs, by studying RSUME effect on pVHL function and to determine the role of RSUME on pVHL-related tumor progression. We determined that RSUME sumoylates and physically interacts with pVHL and negatively regulates the assembly of the complex between pVHL, Elongins and Cullins (ECV), inhibiting HIF-1 and 2α ubiquitination and degradation. We found that RSUME is expressed in human VHL tumors (renal clear-cell carcinoma (RCC), pheochromocytoma and hemangioblastoma) and by overexpressing or silencing RSUME in a pVHL-HIF-oxygen-dependent degradation stability reporter assay, we determined that RSUME is necessary for the loss of function of type 2 pVHL mutants. The functional RSUME/pVHL interaction in VHL-related tumor progression was further confirmed using a xenograft assay in nude mice. RCC clones, in which RSUME was knocked down and express either pVHL wt or type 2 mutation, have an impaired tumor growth, as well as HIF-2α, vascular endothelial growth factor A and tumor vascularization diminution. This work shows a novel mechanism for VHL tumor progression and presents a new mechanism and factor for targeting tumor-related pathologies with pVHL/HIF altered function.

Carcinoma medular de tiroides: estudio multicéntrico. Presentación y evolución en 219 pacientes / Medullary Thyroid Carcinoma: Clinical Presentation and Outcome in 219 Patients

Ante la baja frecuencia del carcinoma medular de tiroides (CMT), en el Departamento de Tiroides de SAEM nos propusimos realizar un estudio de cohorte, observacional, retrospectivo y multicéntrico. Se incluyeron 219 pacientes con diagnóstico histológico de CMT. El 65 % fueron mujeres, la edad promedio fue de 39 ± 20 años (1 a 84 años); 44-% de los casos fueron familiares. Las formas de presentación más frecuentes fueron nódulo tiroideo (58 %) y pesquisa genética por antecedente familiar (22 %). Si bien la citología tiroidea fue diagnóstica de CMT en el 39 % de los casos, fue determinante de indicación quirúrgica en el 79 %. En el 47 % de los pacientes el diagnóstico de CMT se obtuvo previamente al tratamiento quirúrgico inicial por punción aspiración con aguja fina (PAAF), estudio genético o nivel de calcitonina (CT)). El 65 % se presentó en estadios avanzados (TNM III y IV). El estudio del protoncogen RET se realizó en 162 pacientes (74 %). En el 49 % se observó mutación siendo la más frecuente (76 %) en el codón 634. La forma hereditaria más frecuentemente observada fue el síndrome de neoplasia endocrina múltiple (NEM) 2A (57 % de los casos familiares), seguida por carcinoma medular familiar (25 %) y NEM 2B (13 %). Los casos familiares tuvieron menor edad al diagnóstico y mayor frecuencia de diagnóstico prequirúrgico. Los casos índice tuvieron mayor edad al momento del diagnóstico, mayores niveles de antígeno carcinoembrionario (CEA) y CT prequirúrgicos, mayor proporción de estadios III y IV y mayor porcentaje de evidencia de enfermedad al momento de la última consulta que aquellos detectados por pesquisa. En 143 pacientes (65 %) se obtuvieron registros completos de seguimiento en los que se analizaron los factores relacionados con la evolución. La mediana de seguimiento fue de 44 meses: fallecieron 21 pacientes (14,6 %) y 122 (86 %) viven; 76 de estos (54 %) se encuentran libres de enfermedad. El grupo con evidencia de enfermedad se presentó en estadios más avanzados. Resultaron factores de mayor riesgo para evidencia de enfermedad: sexo masculino, CMT esporádico, niveles elevados de CT prequirúrgicos, estadio IV y presencia de metástasis. Los niveles de CT posquirúrgicos fueron menores en aquellos pacientes que en la evolución final no presentaron evidencia de enfermedad. El principal factor pronóstico de la evolución de los pacientes con CMT fue el estadio de presentación, determinando la importancia del diagnóstico precoz con el fin de poder implementar un tratamiento quirúrgico curativo en estadios menos avanzados.

Due to the low frequency of medullary thyroid cancer (MTC), an observational, cohort, retrospective multicenter study was conducted at the Thyroid Department of the Endocrine and Metabolism Argentine Society (SAEM). We included 219 patients with histologically proven MTC, with a mean age of 39 ± 20 yr (range 1-84 years). Sixty five percent were women and 44% were familial cases. The most common presentations were thyroid nodule (58 %) and genetic screening due to family history (22 %). In 39 % of patients, diagnosis of MTC was made by fine needle aspiration, but cytology led to surgery in 79 %. In 47 % of patients, MTC was diagnosed by cytology, calcitonin (CT) levels or genetic studies prior to initial surgery. Sixty five percent of patients had advanced stages of the disease (TNM III or IV) at diagnosis. Proto-oncogene RET was studied in 162 patients (74 %). In 49% a mutation was reported, most frequently in codon 634 (76 %). Regarding hereditary forms of MTC, MEN 2A was the most frequent (57%), followed by familial MTC in 25 % and MEN 2B in 13 % of cases. Familial cases were younger subjects and had more frequently a pre-surgery diagnosis. Index cases were older, with higher CEA and CT levels, presented in more advanced stages and had more frequently evidence of disease at final assessment than patients who were diagnosed by genetic screening. Follow-up records of 143 patients were analyzed (65%); median time was 44 months; 21 patients died (14.6 %) and 122 survived (86 %), 76 showed no evidence of disease (NED) (54 %). High risk factors for evidence of disease at the final evaluation were: male gender, sporadic MTC, higher CT pre-surgery levels, stage IV and metastasis. Post surgery CT levels were lower in patients with NED. Stage at initial diagnosis was the main prognostic factor in patients with MTC, determining the importance of early detection for performing curative surgery in less advanced stages.

Carcinoma medular de tiroides: estudio multicéntrico. Presentación y evolución en 219 pacientes / Medullary Thyroid Carcinoma: Clinical Presentation and Outcome in 219 Patients

Ante la baja frecuencia del carcinoma medular de tiroides (CMT), en el Departamento de Tiroides de SAEM nos propusimos realizar un estudio de cohorte, observacional, retrospectivo y multicéntrico. Se incluyeron 219 pacientes con diagnóstico histológico de CMT. El 65 % fueron mujeres, la edad promedio fue de 39 ± 20 años (1 a 84 años); 44-% de los casos fueron familiares. Las formas de presentación más frecuentes fueron nódulo tiroideo (58 %) y pesquisa genética por antecedente familiar (22 %). Si bien la citología tiroidea fue diagnóstica de CMT en el 39 % de los casos, fue determinante de indicación quirúrgica en el 79 %. En el 47 % de los pacientes el diagnóstico de CMT se obtuvo previamente al tratamiento quirúrgico inicial por punción aspiración con aguja fina (PAAF), estudio genético o nivel de calcitonina (CT)). El 65 % se presentó en estadios avanzados (TNM III y IV). El estudio del protoncogen RET se realizó en 162 pacientes (74 %). En el 49 % se observó mutación siendo la más frecuente (76 %) en el codón 634. La forma hereditaria más frecuentemente observada fue el síndrome de neoplasia endocrina múltiple (NEM) 2A (57 % de los casos familiares), seguida por carcinoma medular familiar (25 %) y NEM 2B (13 %). Los casos familiares tuvieron menor edad al diagnóstico y mayor frecuencia de diagnóstico prequirúrgico. Los casos índice tuvieron mayor edad al momento del diagnóstico, mayores niveles de antígeno carcinoembrionario (CEA) y CT prequirúrgicos, mayor proporción de estadios III y IV y mayor porcentaje de evidencia de enfermedad al momento de la última consulta que aquellos detectados por pesquisa. En 143 pacientes (65 %) se obtuvieron registros completos de seguimiento en los que se analizaron los factores relacionados con la evolución. La mediana de seguimiento fue de 44 meses: fallecieron 21 pacientes (14,6 %) y 122 (86 %) viven; 76 de estos (54 %) se encuentran libres de enfermedad. El grupo con evidencia de enfermedad se presentó en estadios más avanzados. Resultaron factores de mayor riesgo para evidencia de enfermedad: sexo masculino, CMT esporádico, niveles elevados de CT prequirúrgicos, estadio IV y presencia de metástasis. Los niveles de CT posquirúrgicos fueron menores en aquellos pacientes que en la evolución final no presentaron evidencia de enfermedad. El principal factor pronóstico de la evolución de los pacientes con CMT fue el estadio de presentación, determinando la importancia del diagnóstico precoz con el fin de poder implementar un tratamiento quirúrgico curativo en estadios menos avanzados.(AU)

Due to the low frequency of medullary thyroid cancer (MTC), an observational, cohort, retrospective multicenter study was conducted at the Thyroid Department of the Endocrine and Metabolism Argentine Society (SAEM). We included 219 patients with histologically proven MTC, with a mean age of 39 ± 20 yr (range 1-84 years). Sixty five percent were women and 44% were familial cases. The most common presentations were thyroid nodule (58 %) and genetic screening due to family history (22 %). In 39 % of patients, diagnosis of MTC was made by fine needle aspiration, but cytology led to surgery in 79 %. In 47 % of patients, MTC was diagnosed by cytology, calcitonin (CT) levels or genetic studies prior to initial surgery. Sixty five percent of patients had advanced stages of the disease (TNM III or IV) at diagnosis. Proto-oncogene RET was studied in 162 patients (74 %). In 49% a mutation was reported, most frequently in codon 634 (76 %). Regarding hereditary forms of MTC, MEN 2A was the most frequent (57%), followed by familial MTC in 25 % and MEN 2B in 13 % of cases. Familial cases were younger subjects and had more frequently a pre-surgery diagnosis. Index cases were older, with higher CEA and CT levels, presented in more advanced stages and had more frequently evidence of disease at final assessment than patients who were diagnosed by genetic screening. Follow-up records of 143 patients were analyzed (65%); median time was 44 months; 21 patients died (14.6 %) and 122 survived (86 %), 76 showed no evidence of disease (NED) (54 %). High risk factors for evidence of disease at the final evaluation were: male gender, sporadic MTC, higher CT pre-surgery levels, stage IV and metastasis. Post surgery CT levels were lower in patients with NED. Stage at initial diagnosis was the main prognostic factor in patients with MTC, determining the importance of early detection for performing curative surgery in less advanced stages.(AU)

Current advances in anti-influenza therapy.

Every year, influenza epidemics cause numerous deaths and millions of hospitalizations, but the most frightening effects are seen when new strains of the virus emerge from different species (e.g. the swine-origin influenza A/H1N1 virus), causing world-wide outbreaks of infection. Several antiviral compounds have been developed against influenza virus to interfere with specific events in the replication cycle. Among them, the inhibitors of viral uncoating (amantadine), nucleoside inhibitors (ribavirin), viral transcription and neuraminidase inhibitors (zanamivir and oseltamivir) are reported as examples of traditional virus-based antiviral strategies. However, for most of them the efficacy is often limited by toxicity and the almost inevitable selection of drug-resistant viral mutants. Thus, the discovery of novel anti-influenza drugs that target general cell signaling pathways essential for viral replication, irrespective to the specific origin of the virus, would decrease the emergence of drug resistance and increase the effectiveness towards different strains of influenza virus. In this context, virus-activated intracellular cascades, finely regulated by small changes in the intracellular redox state, can contribute to inhibit influenza virus replication and pathogenesis of virus-induced disease. This novel therapeutic approach involves advanced cell-based antiviral strategies. In this review current advances in the anti-influenza therapy for both traditional virus-based antiviral strategies as well as for alternative cell-based antiviral strategies are described focusing on the last 10 years. Anti-influenza compounds are classified on the basis of their chemical structure with a special attention to describe their synthetic pathways and the corresponding structure activity relationships.

Low sodium intake induces an increase in renal monoamine oxidase activity in the rat. Involvement of an angiotensin II dependent mechanism.

AIMS: The interplay between natriuretic dopamine and antinatriuretic angiotensin II represents an important mechanism for the regulation of renal sodium and water excretion. Monoamine oxidase is the main metabolizing pathway for dopamine in the renal cortex. In this study, we have analysed the effect of low sodium feeding and AT1 receptor blockade on renal dopamine metabolism by monoamine oxidase. METHODS: Four groups of rats were studied: 1, normal salt diet (NS); 2, low salt diet (LS); 3, NS receiving Losartan (Los, specific AT1 receptor antagonist, 20 mg kg(-1) bwt day(-1), NS + Los); 4, LS receiving Los (LS + Los). RESULTS: Urinary dopamine excretion was lower in LS than in NS rats (543 +/- 32 vs. 680 +/- 34 ng day(-1) 100 g(-1) bwt, P < 0.05). When treated with Los, DOPAC excretion and urinary DOPAC/dopamine ratio fell significantly in the LS + Los group as compared with the LS group (1199 +/- 328 vs. 3081 +/- 681 ng day(-1) 100 g(-1) bwt and 1.90 +/- 0.5 vs. 5.7 +/- 1.2, respectively, both P < 0.02). Losartan increased hydroelectrolyte excretion in the LS group. No changes were found in the NS + Los group. Aromatic L-amino acid decarboxylase activity in cortex was similar in NS and LS rats. Instead, monoamine oxidase activity was higher in cortical homogenates from LS rats (in nmol mg tissue(-1) h(-1): NS 7.66 +/- 0.52; LS 9.82 +/- 0.59, P < 0.05) and this difference was abolished in LS + Los rats (7.34 +/- 0.49 nmol mg tissue(-1) h(-1), P < 0.01, vs. LS). CONCLUSIONS: We have concluded that low levels of dopamine in the urine of LS rats are because of an increase in the activity of renal monoamine oxidase and that angiotensin II mediates this increase through stimulation of AT1 receptors.

Atenolol improves ventricular function without changing plasma noradrenaline but decreasing plasma atrial natriuretic factor in chronic heart failure.

1 There is good evidence that beta-blockers improve ventricular function, disease progression and survival in patients with left ventricular systolic dysfunction. The aim of this study was to determine the effects of atenolol therapy on the sympathetic nervous system at rest and after ergometric exercise, on left ventricular function and on baseline plasma atrial natriuretic factor (ANF) in ambulatory patients with chronic heart failure (CHF). 2 Twenty-two patients [left ventricular ejection fraction (LVEF) <36%; New York Heart Association II-III] were studied before atenolol treatment. Because of cardiac events (new Hospital admission or death) only 13 patients completed 1 year of treatment. Baseline noradrenaline (NE) concentrations were similar in patients and controls while ANF was higher in patients than in controls (328 +/- 35 pg ml(-1) vs. 37 +/- 3 pg ml(-1); P<0.01). 3 Patients with events showed higher NE (540 +/- 87 pg ml(-1) vs. 303 +/- 44 pg ml(-1); P<0.01) and ANF (460 +/- 70 pg ml(-1) vs. 291 +/- 44 pg ml(-1); P<0.03) at rest; and greater NE response to exercise (2.003 +/- 525 pg ml(-1) vs. 694 +/- 121 pg ml(-1); P<0.005). Atenolol treatment improved LVEF (19.5 +/- 1.9% vs. 33 +/- 3.9%; P<0.001), increased exercise tolerance (9 +/- 3.2 min vs. 17 +/- 4.8 min; P<0.001) and decreased plasma ANF (292 +/- 42 pg ml(-1) vs. 133 +/- 35 pg ml(-1); P<0.01). 4 Reduced basal dihydroxyphenylglycol (DHPG)/NE ratio (3.4 +/- 0.46 vs. 4.3 +/- 0.35; P<0.01) was observed in patients compared with healthy volunteers. Atenolol increased DHPG plasma levels (1.398 +/- 129 pg ml(-1) vs. 913 +/- 86 pg ml(-1); P<0.005) but the DHPG/NE ratio during exercise was not modified after treatment, suggesting that re-uptake of released NE is not changed by beta-blocker treatment. 5 In conclusion, the fact that atenolol treatment improves ventricular dysfunction and clinical status without changing plasma NE levels in CHF patients, suggests that plasma NE is a poor surrogate measurement for cardiac sympathetic activity in this pathology. In addition, decrease in plasma ANF produced by atenolol treatment may reflect the improvement of ventricular function.

Mechanisms of hypothalamic-pituitary-gonadal disruption in polycystic ovarian syndrome.

Although the pathogenesis of polycystic ovarian syndrome (PCOS) is still controversial, a series of investigations has demonstrated an array of neuroendocrine abnormalities as a major component of the syndrome. From a neuroendocrine perspective, patients with PCOS exhibit an accelerated frequency and/or higher amplitude of LH pulses, augmentation of LH secretory burst mass, and a more disorderly LH release. Elevated in vitro LH bioactivity and a preponderance of basic LH isoforms, which correlate positively with elevated serum 17-hydroxyprogesterone, androstenedione, and testosterone concentrations, also characterize adolescents with PCOS. Heightened GnRH drive of gonadotropin secretion and a steroid-permissive milieu appear to jointly promote elevated secretion of basic LH isoforms. Positive feedback is implied, because hypersecretion of highly bioactive LH in PCOS probably contributes to inordinate androgen output. However, the precise nature of feedback disruption remains uncertain. Indeed, recent data suggest that PCOS is marked by anomalies of both feedforward and feedback signaling between GnRH/LH and ovarian androgens. From a single hormone perspective, the individual patterns of LH and androstenedione release are consistently more irregular in patients with PCOS. Bihormonal analysis has disclosed concomitant uncoupling of the pairwise synchrony of LH and testosterone, LH and androstenedione, and testosterone and androstenedione secretion. The foregoing ensemble of findings points to deterioration of both orderly uniglandular and coordinate bihormonal output in PCOS. Additional studies are needed to establish the primary pathophysiologic mechanisms underlying this disorder.

Peripheral administration of an angiotensin II AT(1) receptor antagonist decreases the hypothalamic-pituitary-adrenal response to isolation Stress.

Angiotensin II, which stimulates AT(1) receptors, is a brain and peripheral stress hormone. We pretreated rats with the AT(1) receptor antagonist candesartan for 13 d via sc-implanted osmotic minipumps, followed by 24-h isolation in individual metabolic cages. We measured angiotensin II receptor-type binding and mRNAs and tyrosine hydroxylase mRNA by quantitative autoradiography and in situ hybridization, catecholamines by HPLC, and hormones by RIA. Isolation increased AT(1) receptor binding in hypothalamic paraventricular nucleus as well as anterior pituitary ACTH, and decreased posterior pituitary AVP. Isolation stress also increased AT(1) receptor binding and AT(1B) mRNA in zona glomerulosa and AT(2) binding in adrenal medulla, adrenal catecholamines, tyrosine hydroxylase mRNA, aldosterone, and corticosterone. Candesartan blocked AT(1) binding in paraventricular nucleus and adrenal gland; prevented the isolation-induced alterations in pituitary ACTH and AVP and in adrenal corticosterone, aldosterone, and catecholamines; abolished the increase in AT(2) binding in adrenal medulla; and substantially decreased urinary AVP, corticosterone, aldosterone, and catecholamines during isolation. Peripheral pretreatment with an AT(1) receptor antagonist blocks brain and peripheral AT(1) receptors and inhibits the hypothalamic-pituitary-adrenal response to stress, suggesting a physiological role for peripheral and brain AT(1) receptors during stress and a possible beneficial effect of AT(1) antagonism in stress-related disorders.

Disruption of the synchronous secretion of leptin, LH, and ovarian androgens in nonobese adolescents with the polycystic ovarian syndrome.

The present study probes putative disruption of hypothalamic control of multihormone outflow in polycystic ovarian syndrome by quantitating the joint synchrony of leptin and LH release in adolescents with this syndrome and eumenorrheic controls. To this end, hyperandrogenemic oligo- or anovulatory patients with polycystic ovarian syndrome (n = 11) and healthy girls (n = 9) underwent overnight blood sampling every 20 min for 12 h to monitor simultaneous secretion of leptin (immuno-radiometric assay), LH (immunofluorometry), and androstenedione and T (RIA). Synchronicity of paired leptin-LH, leptin-androstenedione, and leptin-T profiles was appraised by two independent bivariate statistics; viz., lag-specific cross-correlation analysis and pattern-sensitive cross-approximate entropy. The study groups were comparable in chronological and postmenarchal age, body mass index, fasting plasma insulin/glucose ratios, and serum E2 concentrations. Overnight mean (+/- SEM) serum leptin concentrations were not distinguishable in the two study groups at 30 +/- 4.8 (polycystic ovarian syndrome) and 32 +/- 7.4 microg/liter (control). Serum LH concentrations were elevated at 9.5 +/- 1.4 in girls with polycystic ovarian syndrome vs. 2.8 +/- 0.36 IU/liter in healthy subjects (P = 0.0015), androstenedione at 2.8 +/- 0.30 (polycystic ovarian syndrome) vs. 1.2 +/- 0.11 ng/ml (control) (P = 0.0002), and T at 1.56 +/- 0.29 (polycystic ovarian syndrome) vs. 0.42 +/- 0.06 ng/ml (P < 0.0001). Cross-correlation analysis shows that healthy adolescents maintained a positive relationship between leptin and LH release, wherein the latter lagged by 20 min (P < 0.01). No such association emerged in girls with polycystic ovarian syndrome. In eumenorrheic volunteers, leptin and androstenedione concentrations also covaried in a lag-specific manner (0.0001 < P < 0.01), but this linkage was disrupted in patients with polycystic ovarian syndrome. Anovulatory adolescents further failed to sustain normal time-lagged coupling between leptin and T (P < 0.01). Approximate entropy calculations revealed erosion of orderly patterns of leptin release in polycystic ovarian syndrome (P = 0.012 vs. control). Cross-entropy analysis of two-hormone pattern regularity disclosed marked disruption of leptin and LH (P = 0.0099), androstenedione and leptin (P = 0.0075) and T-leptin (P = 0.019) synchrony in girls with polycystic ovarian syndrome. In summary, hyperandrogenemic nonobese adolescents with oligo- or anovulatory polycystic ovarian syndrome manifest: 1) abrogation of the regularity of monohormonal leptin secretory patterns, despite normal mean serum leptin concentrations; 2) loss of the bihormonal synchrony between leptin and LH release; and 3) attenuation of coordinate leptin and androstenedione as well as leptin and T output. In ensemble, polycystic ovarian syndrome pathophysiology in lean adolescents is marked by vivid impairment of the synchronous outflow of leptin, LH and androgens. Whether analogous disruption of leptin-gonadal axis integration is ameliorated by therapy and/or persists into adulthood is not known.

Intermittent hyperaldosteronism in a child due to an adrenal adenoma.

UNLABELLED: Aldosterone producing adenoma (APA) is a rare but potentially curable form of paediatric hypertension. We report a case of APA in a 9-year-old boy, suspected due to persistent hypokalaemia. Neither BP nor initial laboratory investigations disclosed the diagnosis and the presence of an APA was suggested by functional tests and radiological findings. Histologically, a cortical tumour was found associated with a marked medullary hyperplasia of both chromaffin and ganglion cells. CONCLUSION: This case reinforces the need for further investigations in patients with misleading clinical and laboratory data.

Disruption of the joint synchrony of luteinizing hormone, testosterone, and androstenedione secretion in adolescents with polycystic ovarian syndrome.

The present study explores the postulate that the polycystic ovarian syndrome (PCOS) is marked by failure of physiological feedforward and feedback signaling between pituitary LH and ovarian androgens. To this end, we appraised the 3-fold simultaneous overnight release of LH (assayed by high precision immunofluorometry), testosterone (RIA), and androstenedione (RIA) in 12 an- or oligoovulatory adolescents with PCOS (mean +/- SEM age, 16.4 +/- 0.47 yr) and 10 eumenorrheic girls (age, 16.5 +/- 0.45 yr). Gynecological (postmenarchal) ages (years) were also comparable at 4.8 +/- 0.39 (PCOS) and 4.0 +/- 3.6 (control; P = NS). Body mass index and fasting serum insulin and estradiol concentrations were indistinguishable in the two study cohorts. Mean overnight serum concentrations of LH (assayed by both immunofluorometry and Leydig cell bioassay), testosterone, androstenedione, and 17alpha-hydroxyprogesterone were each elevated significantly in patients with PCOS (all P

Decreased tubular uptake of L-3,4-dihydroxyphenylalanine in streptozotocin-induced diabetic rats.

BACKGROUND/AIMS: This study determined alterations in renal dopamine production in streptozotocin-treated rats and explored the mechanisms underlying this alteration. METHODS: Streptozotocin (65 mg/kg) or vehicle was administered to 3-month-old male Wistar rats. Treated animals had hyperglycemia, glycosuria and increased diuresis, natriuresis and excretion of L-dopa. Urinary dopamine and dihydroxyphenylacetic acid were similar to those in control animals. The production of dopamine by renal cortex slices from treated rats was significantly less than that from control animals. The addition of glucose (8.4-18.4 mM) to the incubation medium decreased about 40% the uptake of L-dopa by isolated proximal tubular cells. Scatchard analysis of the saturation curves obtained in this condition showed a decrease in the V(max) without changes in the K(m). RESULTS: Our results confirm previous studies suggesting a renal dopaminergic deficiency in insulin-dependent diabetes and provide evidence strongly suggesting that a decrease in the number of tubular L-dopa transport sites is the underlying defect of this deficiency. CONCLUSION: These results highlight the role of the uptake of dopa as an important modulator of renal dopamine synthesis.

Correlation of increased grooming behavior and motor activity with alterations in nigrostriatal and mesolimbic catecholamines after alpha-melanotropin and neuropeptide glutamine-isoleucine injection in the rat ventral tegmental area.

1. We wished to further study the behavioral effects of alpha-melanotropin (alpha-MSH), melanin-concentrating hormone (MCH), and neuropeptide glutamine-isoleucine (NEI). 2. To this effect we administered alpha-MSH, MCH, and NEI in the ventral tegmental area of the rat, a structure where these neuropeptides are highly concentrated. To further elucidate the biochemical mechanisms of the behavioral effect of these neuropeptides, we determined the degree of grooming behavior and the levels of catecholamines. after neuropeptide administration. 3. We preselected those animals responding to the central injection of alpha-MSH with excessive grooming behavior. We administered the neuropeptides at the dose of 1 microg/0.5 microL, in each side of the ventral tegmental area, bilaterally. We studied grooming behavior, locomotor activity, and total behavior scores, 30 and 65 min after administration of the peptides. 4. Three groups of animals were decapitated immediately after the injection of the neuropeptides, and 30 or 65 min after injection. We measured dopamine (DA), noradrenaline (NA), and the dopac/dopamine ratio (DOPAC/DA) to determine steady state levels of catecholamines and an indirect measure of DA release and metabolism, respectively. 5. Injections of alpha-MSH produced significant elevations in grooming behavior, locomotor activity, and total behavior scores, both 30 and 65 min after peptide administration. This was correlated with significant decreases in DA content, increases in DOPAC content, and increases in the DOPAC/DA ratio. In the caudate putamen, changes in catecholamines occurred both at 30 and 65 min after injection. In the nucleus accumbens, changes were present at 65 min after injection. Conversely, there were no alterations in NA content, either in the caudate putamen or in the nucleus accumbens, at any time after the injection. 6. Injections of NEI resulted in significant elevations in grooming behavior, locomotor activity, and total behavior scores, both 30 and 65 min after peptide administration. This was correlated with increased DOPAC/DA ratio in the nucleus caudatus but not in the nucleus accumbens. Conversely, NEI produced increased NA concentrations in the nucleus accumbens, but not in the nucleus caudatus. 7. Injections of MCH did not produce significant changes in behavior or significant changes in nucleus caudatus or nucleus accumbens catecholamines. 8. Our results indicate (a) There is a correlation with alterations in behavior as induced for the neuropeptides injected here, and changes in extrapyramidal catecholamines. (b) There is a correlation between alterations in behavior and increases in DOPAC/DA ratio in the nucleus caudatus. (c) There is a correlation between alterations in behavior and alterations in catecholamines in the nucleus accumbens. In the nucleus accumbens, DOPAC/DA ratio is changed after alpha-MSH, and NA ratio is changed after NEI injection. (d) Absence of alterations in extrapyramidal catecholamines, and in particular in catecholamines in the nucleus accumbens, correlates with absence of behavioral alterations after neuropeptide administration to the ventral tegmental area. 9. In conclusion, the behavioral effect of exogenous administration of neuropeptides in the ventral tegmental area is peptide-specific, and is probably associated with alterations in catecholamine metabolism and release in the nucleus caudatus and the nucleus accumbens. Both alpha-MSH and NEI seem to stimulate the nigrostriatal DA system. While alpha-MSH appears to stimulate the mesolimbic DA system as well, NEI may exert its actions not through the DA, but through the NA mesolimbic system. The precise contribution of DA and NA, and the relative role of the nucleus caudatus and nucleus accumbens in these behaviors remain to be elucidated.

Effects of thyroid hormone on the renal dopaminergic system.

This study determined the effects of thyroid hormone on the renal dopaminergic system. Surgical thyroidectomy (Tx) and treatment with 2-thiouracil (Thio) decreased renal cortex Na+/K+ ATPase activity and urinary volume. Tx also decreased urinary Na+ and urinary L-DOPA without changing urinary excretion of Dopamine (DA). Thio treatment decreased slightly urinary L-DOPA and Na+, but increased urinary excretion of DA. In both models of thyroid hormone deficiency, the ratio urinary DA/DOPA increased. Changes after Thio treatment were reversed after one month of drug withdrawal. Treatment with T3 via osmotic minipump increased Na+/K+ ATPase activity and urinary L-DOPA, did not change urinary DA, and increased the ratio DA/DOPA. To further analyze the effects of thyroid hormone deficiency, we administered selective DA1 (SCH-23390), DA2 (Sulpiride), and a non selective (Haloperidol) DA receptor antagonists to Thio treated and control animals. The DA1 antagonist decreased diuresis, natriuresis and urinary L-DOPA in control, but had no effect in Thio treated rats. Sulpiride had no effect in either group. The combination of SCH-23390 plus Sulpiride decreased urinary L-DOPA and urinary volume only in Thio treated animals. Haloperidol decreased urinary volume in Thio treated animals, but had no effect in controls. Our findings suggest that renal DA synthesis is to some extent dependent on thyroid hormone levels, and that the response of DA receptors is altered by thyroid hormone deficiency, indicating a role of this hormone in the regulation of the renal dopaminergic system.

L-Dopa uptake and dopamine production in proximal tubular cells are regulated by beta(2)-adrenergic receptors.

This study assessed the role of adrenergic receptors on the regulation of the uptake of L-dopa and the production of dopamine by renal tubular cells. Scatchard analysis showed two L-dopa uptake sites with different affinities (K(m) 0.316 vs 1.53 microM). L-Dopa uptake was decreased by the nonselective adrenergic agonists epinephrine or norepinephrine (40%), by the beta-selective agonist isoproterenol or the beta(2)-selective agonist terbutaline (60%), but not by alpha-selective agonists (all 1 microM). The effect of norepinephrine, isoproterenol, or terbutaline was unaffected by addition of the beta(1)-antagonist atenolol, abolished by ICI-118, 551, a beta(2)-antagonist (both 0.1 microM), and mimicked by the addition of dibutyryl-cAMP (1 microM). Preincubation with terbutaline decreased the number of high-affinity uptake sites (V(max) = 1.10 +/- 0.3 vs. 0.5 +/- 0.1 pmol. mg protein(-1). min(-1)) without changing their affinity. Norepinephrine or terbutaline decreased dopamine production by isolated cells, and this effect was abolished by ICI-118,551 (0.1 microM). In vivo administration of ICI-118,551 reduced the urinary excretion of L-dopa and increased the excretion of 3,4-dihydroxyphenylacetic acid without significant changes in plasma L-dopa concentrations. These results demonstrate that stimulation of beta(2)-adrenergic receptors decreases the number of high-affinity L-dopa uptake sites in isolated tubular cells resulting in a reduction of the uptake of L-dopa and the production of dopamine and provide evidence for the presence of this mechanism in the intact animal.

A preponderance of basic luteinizing hormone (LH) isoforms accompanies inappropriate hypersecretion of both basal and pulsatile LH in adolescents with polycystic ovarian syndrome.

We recently demonstrated that adolescent girls with polycystic ovarian syndrome (PCOS) exhibit augmented LH secretion due to an increase in immunofluorometric and deconvolution-estimated LH secretory burst mass and pulse frequency. Concurrently, we inferred either a prolongation of apparent (endogenous) LH half-life or elevated basal (nonpulsatile) LH release in PCOS. The in vivo half-life of LH molecules can be affected by the oligosaccharide side-chains, which also modify in vitro bioactivity and electrostatic change. Accordingly, as a surrogate estimator of altered endogenous LH half-life and/or biopotency in PCOS, we characterized the isoelectric properties of secreted LH isoforms and determined their in vitro biological activity in adolescent girls with PCOS compared with healthy age-matched eumenorrheic controls. To this end, 12-h (overnight) serum samples from PCOS patients (n = 12) and normal adolescents (n = 10) were pooled by subject. Bioactive LH concentrations were then quantitated in a rat Leydig cell in vitro bioassay, and immunological activity was determined by immunofluorometry. The distribution of LH isoforms was evaluated by preparative chromatofocusing (pH window, 10.5 to <4.0) of samples further combined to yield three independent serum pools for each of the patient and control groups. Fasting serum concentrations of 17-hydroxyprogesterone (17-OHP), androstenedione, testosterone, estrone, estradiol, and sex hormone-binding globulin were determined as possible endocrine correlates of LH isotypes. Mean serum concentrations of immunoreactive and bioactive LH in adolescents with PCOS were 3 and 2 times higher than values in controls: immunoreactive: PCOS, 7.8+/-0.9; controls: 2.6+/-0.3 IU/L (P < 0.001); and bioactive: PCOS, 52+/-10; controls, 25+/-4.1 IU/L (P = 0.002), respectively. Bioactive LH concentrations correlated positively with 17-OHP (P = 0.022), androstenedione (P = 0.012), and testosterone (P = 0.046) concentrations in PCOS. Chromatofocusing of LH isoforms disclosed greater LH immunoreactivity at pI values greater than 8 and 7.99-7.0 in adolescents with PCOS compared with controls (P = 0.031). The percentage of basic LH isoforms was related positively to serum concentrations of 17-OHP (P = 0.032), androstenedione (P = 0.046), and testosterone (P = 0.040). In conclusion, the present isotype analysis demonstrates elevated in vitro LH bioactivity and a preponderance of basic LH isoforms in girls with PCOS. Since previously reported heterologous in vivo assays of LH kinetics point toward accelerated removal of such alkaline isotypes, our findings would favor the earlier alternative hypothesis of inappropriate hypersecretion of basal (interpulse) LH rather than prolongation of the LH half-life as the mechanism for elevated interpulse serum LH concentrations in adolescents with PCOS. In ensemble, the foregoing data thus suggest 3-fold amplification of basal LH secretion as well as both a heightened amplitude and frequency of the pulsatile mode of LH release in PCOS.

Increased plasma atrial natriuretic factor in catecholamine-producing tumor patients.

The aim of this study was to evaluate plasma levels of ANF in patients with catecholamine-secreting tumors with and without hypertension and to relate ANF secretion to levels of plasma and urinary catecholamines and blood pressure. Twenty-one pheochromocytoma (15 with sustained, 6 with paroxysmal hypertension), 6 neuroblastoma (1 hypertensive) patients and 28 aged-matched controls were studied in basal conditions. Plasma and urinary norepinephrine (NE),epinephrine (E), dopamine (DA) and DOPA were determined by HPLC-ED and plasma ANF by RIA. Both neuroblastoma and pheochromocytoma patients had significantly higher plasma ANF levels than controls. Neuroblastomas showed higher ANF concentration than pheochromocytomas. No differences were found in plasma ANF between hypertensive and normotensive patients. Pheochromocytomas with ANF levels within the normal range had plasma and urinary NE and urinary DA and DOPA levels significantly higher than patients with high ANF. Plasma ANF levels were unrelated to systolic or diastolic blood pressure or heart rate. A negative correlation between plasma ANF and urinary DA was found only in the patients groups. In conclusion, plasma ANF was increased in pheochromocytoma and neuroblastoma patients. Our data suggest that the excessive catecholamine secretion is not responsible for the increased ANF secretion in these patients. The significance of the relationships among plasma ANF and urinary and plasma catecholamines requires further investigation.

Influence of age on stress responses to metabolic cage housing in rats.

1. We studied the effect of isolation stress in 3- and 12-month-old rats individually housed in metabolic cages for 7 days. Urine (24 hr) was collected daily from one group of animals of each age. The other group was tested in an open field and on a hot plate on days 1 and 7. 2. Total deambulation in the open-field test was lower in young than in older rats both on day 1 (54.7 +/- 9.9 vs 80 +/- 8.9 crossings/session; P < 0.04) and on day 7 (21 +/- 9 vs 48 +/- 7 crossings per session; P < 0.04) and decreased significantly in the two groups when tested on day 7 (P < 0.03). Latency to paw-licking in the hot-plate test was longer in young than in older animals on day 1 (14 +/- 2 vs 8 +/- 4 sec; P < 0.05) but was similar in the two groups on day 7. 3. Urinary excretions of norepinephrine (NE) and epinephrine (E) were determined by HPLC with electrochemical detection. Urinary NE in day 1 was similar in young and older animals (2627 +/- 828 vs 3069 +/- 598 ng/24 hr). In young animals NE excretion decreased along the study and was significantly (P < 0.02) lower than on day 1 during the last 3 days of the study. Conversely, in older animals urinary excretion of NE remained similar throughout the study. On day 7 urinary excretion of NE in older animals was about two fold that in young rats. Urinary E was similar in young and older rats (341 +/- 127 vs 532 +/- 256 ng/24 hr) on day 1 and showed a tendency to increase throughout the study. 4. Urinary monoamine oxidase inhibitory (IMAO) activity was determined by testing the ability of urine extracts to inhibit rat liver MAO activity in vitro and was higher in young than in older animals throughout the study (day 1, 54.8 +/- 4.2 vs 25.1 +/- 5.1%; P < 0.02). In young rats excretion of IMAO was significantly higher during the last 3 days of the study than on day 1 (P < 0.05). In older animals urinary IMAO showed a tendency to increase at the end of the study. 5. Isolation stress caused by housing rats in metabolic cages results in different behavioral and metabolic responses in young and older animals. Young animals exhibit a lower locomotor and analgesic response and excrete lower amounts of NE and higher IMAO activity in the urine than older rats. The metabolic and behavioral responses to isolation stress are highly dependent on the age of the animals tested. These results should be taken into consideration when designing experiments requiring the use of metabolic cages.