Insulinoma, presentación y evolución de dos casos clínicos / Insulinoma, evolution and presentation of 2 clinical cases

Insulinoma is a very uncommon tumor in children, with an incidence in adults of 2 per million inhabitants. Clinical manifestations include neuroglycopenic or autonomic manifestations due to hypoglycemia. We describe 2 pediatric patients with insulinoma, characterized by repeated episodes of hypoglycemia associated to high insulin serum levels and presence of a small mass in the pancreas by imaging studies. The diagnosis was very prompt in one case and delayed in the other, emphasizing the need for an appropriate diagnosis of hypoglycemia during childhood.

El insulinoma es un tumor muy infrecuente en la edad pediátrica y la incidencia reportada en adultos es de 2 casos por millón de habitantes. La presentación de la enfermedad consiste en la presencia de síntomas neuroglicopénicos y autonómicos desencadenados por los episodios de hipoglicemia. Se describen dos pacientes con insulinoma esporádico. El cuadro clínico consistió en episodios repetidos de hipoglicemia asociados a niveles aumentados de insulina sérica y a imágenes sugerentes de un tumor pancreático. El diagnóstico fue muy oportuno en uno de los casos y muy tardío en el otro, lo que resalta la necesidad de estar muy alerta ante casos de hipoglicemia durante la niñez.

Efecto de la administración de triiodotironina y glucagón sobre la expresión hepática del receptor de lipoproteínas de alta densidad y el metabolismo del colesterol en el ratón / Effect of triiodothyronine (T3) and glucagon on hepatic expression of SR-BI and lipoprotein cholesterol metabolism in mice

Introducción: El receptor scavenger clase B tipo I (SR-BI) es un elemento clave en el metabolismo de las HDL, donde su expresión ejerce un importante efecto anti-aterogénico controlando la fase hepática del transporte reverso de colesterol. Así, el estudio de la modulación de la expresión de SR-BI permitiría el desarrollo de nuevas alternativas farmacológicas para el tratamiento de la ateroesclerosis. Objetivo: La meta de nuestro estudio fue determinar el efecto de la triiodotironina (T3) y el glucagón sobre el metabolismo del colesterol HDL y la expresión hepática de SR-BI en el ratón, evaluando simultáneamente su impacto sobre el colesterol total y lipoproteico plasmático y la secreción biliar de colesterol. Métodos: Se utilizaron ratones C57BL/6 tratados con T3 (30 nmol/kg/día) o glucagón (80 µg/día) más los respectivos grupos controles. Después del tratamiento, los animales se anestesiaron para recolección de bilis, plasma y tejido hepático. Los niveles totales de colesterol plasmático y biliar fueron medidos por métodos enzimáticos. El colesterol lipoproteico plasmático se evaluó por fraccionamiento cromatográfico del plasma y medición enzimática del colesterol en cada fracción. La expresión hepática de SR-BI se cuantificó mediante western blot. Resultados: El uso de T3 o glucagón disminuyeron significativamente el colesterol plasmático total y aumentaron el colesterol biliar con respecto al grupo control correspondiente. Las fracciones de colesterol VLDL, LDL y HDL disminuyeron en ambos grupos tratados, con un mayor efecto observado en la fracción HDL. La administración de ambas hormonas aumentaron significativamente los niveles hepáticos de SR-BI. Conclusión: Los resultados establecen que T3 y glucagón disminuyen el colesterol plasmático, predominantemente de tipo HDL, y aumentan la secreción de colesterol biliar en el ratón, probablemente como consecuencia del incremento en la expresión hepática...

Introduction: The scavenger receptor class B type I (SR-BI) plays a key role in the metabolism of high-density lipoprotein (HDL) cholesterol. Its expression has an important anti-atherogenic effect by controlling the hepatic phase of the reverse cholesterol transport pathway in vivo. Thus, the study of the modulation of SR-BI expression may allow the development of new pharmacologic approaches for treatment of atherosclerotic cardiovascular disease. Objective: The goal of this study was to determine the effect of triiodothyronine (T3) and glucagon on HDL metabolism and hepatic expression of SR-BI in mice, evaluating also the impact in total and lipoprotein cholesterol as well as biliary cholesterol secretion. Methods: C57BL/6 mice were treated with T3 (30 nmol/kg/día) or glucagon (80 µg/día) in comparison to appropriate control groups. After treatment, bile, plasma and hepatic tissue were collected for analysis. Total plasma and biliary cholesterol levels were measured by enzymatic methods. Lipoprotein cholesterol was also measured enzymatically after chromatographic separation of plasma samples. The hepatic expression of SR-BI protein was quantified by western blotting. Results: The use of T3 or glucagon significantly decreased total plasma cholesterol levels and increased of biliary cholesterol concentrations compared to control groups. Levels of VLDL, LDL and HDL cholesterol were reduced in both treatment groups, with a more important effect observed in the HDL fraction. Both treatments increased hepatic SR-BI protein levels. Conclusions: These results show that T3 and glucagon decrease plasma cholesterol levels, particularly in HDL, and increase biliary cholesterol secretion in mice, probably as a consecuence of higher hepatic expression of SR-BI, which may have led to facilitated HDL cholesterol transport from plasma into bile.

Hyperinsulinemic-euglycemic therapy for intoxication with calcium channel blockers

Conventional therapy for intoxication with calcium channel blockers consists of crystalloid solutions, calcium gluconate, glucagon and vasopressor agents. These therapies often fail to improve hemodynamic function in intoxicated patients. The pathophysologic mechanism proposed for intoxication with these agents, suggest hypoinsulinemia as the determinant factor. We will describe the case of a 77 years old man treated for an overdose of nifedipine and atenolol who arrived at our institution with hypotension and bradycardia. After conventional therapy failed to improve the patient's hemodynamic status, hyperinsulinemia and euglycemia contributed to the improvement of the patient's neurologic and hemodynamic condition. Thus, hyperinsulinemic-euglycemic therapy was of benefit in this patient with hemodynamic compromise secondary to intoxication with calcium channel blocker not responding to conventional therapy. We will review the mechanism of action of calcium channel blocker drugs as well as the clinical presentation and treatment options for calcium channel blocker intoxication.

Persistent hyperinsulinemic hypoglycemia of infancy: experience at Siriraj Hospital.

BACKGROUND: Persistent hyperinsulinemic hypoglycemia of infancy (PHHI) is the most common cause of recurrent or persistent hypoglycemia in early childhood. Conventionally, pancreatectomy (Px) has often been recommended to control hypoglycemia. However, PHHI can be managed successfully by intensive medical treatment to avoid pancreatectomy. METHOD: Data from 10 infants (8M, 2F) with PHHI were retrospectively analyzed. RESULTS: Eight patients (80%) developed symptoms within 72 hours after birth (early-onset). Six patients (60%) underwent 85 per cent-95 per cent Px due to failure of medical treatment. Two patients who underwent less than 95 per cent Px required second Px (97% and 99%). One patient developed permanent diabetes mellitus and malabsorption. Hypoglycemia could be successfully managed by medication alone in four patients (40%). Of these, three patients had early-onset neonatal hypoglycemia. Medication could be discontinued in three patients (75%). Three of ten patients (30%) had delayed development. Pancreatectomies and/or the diagnosis of PHHI were made late for these patients. One of these three children also developed epilepsy. CONCLUSIONS: Patients with PHHI frequently require pancreatectomy which commonly results in long-term complications especially diabetes mellitus and malabsorption. Our data suggest that PHHI can be managed successfully with an intensive medical regimen even in patients with early-onset hypoglycemia. Although medical management is very laborious for the family and physician, it should be applied until euglycemia is accomplished. Moreover, the early diagnosis of PHHI and the successful hypoglycemic control are very necessary to prevent permanent neurologic sequelae.

Effect of conbined administration of counterregulatory hormones during insulin-induced hypoglycemia in rats: lipolysis mediated by a Beta-adrenergic mechanism contributes to hyperglycemia

The synergistic effect of combined injection of glucagon (G), cortisol (C) and phenylephrine + isoproterenol (E) during hypoglycemia in male adult Wistar rats was investigated. For this purpose we injected insulin (1 mg/kg), individually or combined (G+C, G+E, C+E and C+G+E). All drugs were injected ip and all rats were killed 60 min after insulin injection. The rise in glycemia with C+G+E was greater (delta = 107 mg/dl) than the sum of the responses to injection of C, G and E individually, or in double combination plus any single hormone injection. This synergistic effect was reproduced by G + C + isoproterenol (Iso) but not by G + C + phenylephrine (delta = 0 mg/dl). The results also showed a clear relationship between hyperglycemia and lipolysis. Thus, lipolysis mediated by a ß-adrenergic mechanism played a significant role in promoting hyperglycemia when Iso was combined with G and C

Antídotos de uso reciente

Los antídotos son sustancias cuya función es contrarrestar el efecto farmacológico y tóxico de otras sustancias, teniendo en cuenta la importancia de las medidas generales en el manejo del intoxicado (baño general, emesis, lavado gástrico, carbón activado, catárticos). Cada día aparecen sustancias nuevas con dichas características. En el presente artículo se pretende dar información breve y detallada sobre las propiedades farmacológicas, indicaciones, dosificación, efectos secundarios y contraindicaciones de algunos de uso general (carbón activado, soluciones electrolíticas con polietilenglycol) y principalmente de algunos específicos de uso reciente: flumazenil, fragmentos Fab-antidigoxina, glucagón, naloxona, clonidina, N-acetil-cisteína, azul de metileno, nitrito y tiosulfato de sodio, ácido-2-3-dimercaptosuccínico, penicilina benzatínica, glicopirrolato y S-adenosil-metionina.

Effect of centrally administered glucagon on liver glycogen & enzymes in anaesthetised dogs.

Glucagon (0.01 microgram) administered through the intracerebroventricular route in anaesthetised mongrel dogs, caused a significant rise in blood glucose and a fall in liver glycogen (P less than 0.01). Concurrently, it increased the liver phosphorylase, glutamic oxaloacetic transaminase, glutamic pyruvic transminase and lipase activities by 30 min. Identical changes were observed in vagotomised animals. In pancreatectomised animals as well as in spinal cord transectomised animals, glucagon did not cause these changes. The study indicated that the hyperglycaemia produced by the centrally administered glucagon, is possibly a result of liver glycogenolysis and gluconeogenesis induced by endogenous glucagon secreted from the pancreas, the stimulus for which is the hypothalamo-pancreatic fibres responding to glucagon sensitive neurones in the hypothalamus.

Effect of centrally administered glucagon on blood lipids in anesthetised dogs.

Previously we have proposed the existence of the central glucagon sensitive receptors in dogs. The present study was undertaken to explore the role of centrally administered glucagon on lipids in view of the proposed theory that the hypothalamic lipomobilizing centres are sensitive to glucose or substances that affect glucose metabolism. Glucagon (0.01 microgram) administered through the intracerebroventricular (ICV) route in anesthetised mongrel dogs, caused hypolipidemia (P greater than 0.001), hypocholesterolemia (P greater than 0.001), decreased blood free fatty acid (P greater than 0.001) and triglycerides (P greater than 0.001) levels; but increased blood high density lipoprotein (P greater than 0.01) level at 30 min. These effects on the central administration of glucagon, were not observed in pancreatectomised animals and spinal cord transectomised animals. Therefore, we conclude that the lipolysis on the central administration of glucagon, is caused by the endogenous glucagon secreted from the pancreas through the sympathetic fibers.

Effect of centrally administered glucagon on urinary sodium and potassium concentration in dogs.

The effects of glucagon administration through intracerebroventricular (ICV), third ventricular (TV) and intracisternal (I") routes on urinary sodium and potassium concentration have been studied in mongrel dogs. The central administration of glucagon resulted in a significant decrease in urinary sodium concentration (P less than 0.01) and increase in urinary potassium concentration (P less than 0.001). This change in urinary sodium and potassium concentration on central administration of glucagon was abolished in animals which were ventured to either sympathetic denervation or adrenalectomy. The observations in the present study suggest that the changes in urinary sodium and potassium concentration on central administration of glucagon, are due to increased secretion of some substance from the adrenals and the probable efferents might be the sympathetic fibres.

Effect of centrally administered glucagon on urine output in dogs.

The effect of minimal doses of glucagon, administered by intracerebroventricular (ICV) and intracisternal(IC) routes, on urine output in mongrel dogs have been studied. The dose of 2.0 mug of glucagon was found to be the minimal dose for diuresis on peripheral administration. This dose when centrally administered, produced an oliguric effect in animals. This effect was not observed in vagosympathectomised-spinal cord transectomised or adrenalectomised animals. It is suggested that the probable efferents might be the sympathetic fibres as they are present in vagi nerves as well in the spinal cord (26). The observations made in an attempt to find out the organ responsible for the oliguric effect, showed that some substance released from the adrenal cortex has an influence on the kidney's excretory function.