La neurocirugía en los trastornos de la alimentación: ¿una alternativa posible?

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Abstract: Composition and quantity of food in-taken varies considerably between one meal and another, or between one day and the following. Non biological factors -such as emotional, social, day time, feasibility in the type of food, and cost- are, among others, factors that in some way affect the degree of energy in-take by food, which generally is not related with daily energy expenditure. These phenomena represent an active process of regulation that is characterized by the balance between signs that stimulate hunger, called orexigenics and those that produce satiation to stop in-take, called anorexigenics, that promotes the stability in the quantity of corporal energy manifested as fat. In this feeding regulatory process there are many molecular signs that participate and regulate the in-take of behaviour food for homeostasis. There are two hypothalamic centers related with the food in-take control: the hunger centre in the lateral hypothalamus and the satiation centre in the ventromedial nucleus. In this control many impulses participate, regulated by substances called neurotransmitters, such as: neuropeptide Y, galanine, orexines for the hunger centre and nor epinephrine, serotonin, and dopamine for the satiation centre. Insulin reaches the brain through circulation and acts reducing the contribution of energy, it was the first hormonal sign that was implicated in weight control by CNS. The second identified hormone, secreted by the adiposity, was leptin. Both hormones circulate in levels proportional to the corporal fat and get to the CNS in proportion to its plasmatic concentrations. Receptors as leptin and insulin are expressed by brain neurons involved in the contribution of energy, and the administration of any of both peptides directly to the brain, reduce the in-take of food. The lack of any of these hormones produces the opposite. Leptin has a more important role than insulin in the control of the energetic homeostasis in the CNS. For example, the lack of leptin causes severe obesity with hyperfagia that persists regardless the levels of elevated insulin. In contrast, obesity isn't induced by the lack of insulin. Insulin has a critic role to promote the storage of fat and the synthesis of leptin through the fat cellule. The neuropeptide Y, produced in the arcuate nucleus of the hypothalamus has an anabolic effect. The gene of expression and secretion of this peptide in the hypothalamus increases during depletion, in the storage of corporal fat and/or when the signs of leptin/insulin are decreased in the brain. Leptin inhibits the gene of expression of the neuropeptide Y in the arcuate nucleus and the genetic "knockout" of the NPY reduces hyperfagia and obesity in mice ob/ob, indicating that the total response to the lack of leptin requires the signs of the NPY. Other substances like the Agouti protein (AGRP), the orexines (hypocretines A and B) and the concentrations of the melancortin hormone have been added to the molecule candidate list with anabolic effects. Also in the adjoining neurons of the arcuate nucleus, are originated anorexigenic peptides like alfa-MSH (a derivated of the pro-opiomelancortin, POMC) and CART (transcript protein related with cocaine and amphetamine). Both types of neurons (NPY/AGRP and POMC/CART) coexpress the leptin receptors. In those situations in which the levels of leptin or insulin are low, the NPY/AGRP neurons activate and the POMC/CART are inhibited. This suggests that the main site of adiposity signs transformation is a neuronal response in the arched nucleus. The link between the lateral hypothalamus and the elevated centers of the brain that regulate hunger and satiation is a very important aspect of the regulation system. There have been typified two types of neuropeptides linked to neurons, that appear to be exclusively of the lateral hypothalamus area: the concentrated melanin hormone (MCH) and the orexines. At the lateral zone, there have been specified two types of hypothalamic neuropeptides, the orexines A and B, also known as hypocretines 1 and 2, which are cellular bodies of the hypothalamus, especially at the lateral hypothalamus and the perifornical area, which stimulate the appetite in an independent way to other neuropeptides known. On the other hand, the orexines A and B derive (by proteolysis) of a common precursor, and are capable of activating their two respective receptors that work in conjunction with proteins G. The central administration of orexines stimulates the in-take and production of orexines' increase with fasting. These neuropeptides match with the hypocretines described by other authors, with expression in late ral hypothalamus, arched nucleus, septal nucleus and forebrain. Monoaminergic neurotransmitters. Noradrenalin Noradrenalin is synthesized in different areas of the brain such as the dorsal nucleus of the vague and the locus coeruleus.Noradrenalin shares the same place with NPY and the injection of both inside the preventricular nucleus increase the in-take of food. The repeated injection can result in weight increase; leptin can inhibit noradrenalin secretion. Dopamine Critic dependence of the in-take of food in the CNS is given by the dopamine sign, which is implicated in the voluntary lack of the food in-take. Motor alterations associated with the lack of dopamine affect also the alimentary behavior. The dopamine effect over the alimentary behavior varies depending of the studyied area. For example the routes of dopamine in the mesolimbic area contribute to the reward of the in-take of savory food. SerotoninThe 5HT2c receptor of serotonin is implicated in the decrease of the in-take of food and the weight increase, due to its effect in the impulse of the satiation centre. To maintain the homeostasis of normal energy it is necessary that the serotonin sign be intact. New alternative hypothesis. On one hand, the knowledge of regulation of the appetite-satiety neuroendocrine cycle, and on the other, the new techniques of neuromodulation through stereotaxic surgery, allow to offer an extraordinarily interesting field of research in certain patients with feeding disorders of difficult control and with an increase in the mortality risk. The alternative of controlling specific centers of hunger/satiation regulation, is still a hypothesis, though there are some data that allow us to assume that it could be feasible and we will mention them after. Current experience. Stereotaxic (Latin: stereo, three-dimensional; taxis, positioning) is a modern technique of neurosurgery that allows the localization and precise access to intra-cerebral structures, through a small orifice in the skull. If we have identified the places that regulate the intake of food or satiety, it is feasible that through this technique we can stimulate or inhibit this function and offer the patient an alternative that in theory could be feasible. Some of its possible advantages will be that we are talking about a minimum invasive surgery, generally performed using local anesthesia; patients need a minimum hospitalization stay and surgical risks are minimized. This allows us to predict in the majority of the patients a satisfactory evolution of weight decrease. The current experience of stereotaxic used in eating disorders is null; everything about it is hypothetic. However, the use of this proceeding for other accepted indications where there is previous experience, has allowed us to obtain interesting data of the evolution of these patients that shows indirectly, that the procedure has influenced in the corporal weight. We present these indirect results, which motivate us to continue considering its possible use in patients that show the approved profile according to an ethic committee properly authorized. In depression or bipolar disorder cases, the use of the stereotaxic surgery applying electrodes in the bottom pedunculo thalamic region (ITP), independently that they show an improve in their basal alteration, the patients show a weight increase, inferring a relationship of this area and the one of the hypothalamus for the appetite/satiation control, situation that hypothetically could benefit patients with anorexia nervosa or bulimia. In the cases with Parkinson Disease, the stereotaxic procedure has been made in the pre-lemniscal (RAPRL) or the subtalamic region (STN) in a unilateral or bilateral way, and although the response hasn't been uniform, the weight changes showed a decrease, making this a possible alternative to be used in some patients with morbid obesity according to the inclusion criteria. Final comments. The expectative of stereotaxic surgery in handling patients with difficult to control feeding disorders or with high risk of morbid-mortality, is shown as an hypothesis, that should consider the specific rules of good clinical practices and adjust to the rules of an approved ethics committee, for these procedures.

La osteoporosis en el varón es un riesgo frecuentemente ignorado / Osteoporosis in the male is a frequently ignored risk

Durante muchos años la osteoporosis se ha considerado una enfermedad que afecta al sexo femenino, sin embargo en el hombre, el envejecimiento y la disminución de las concentraciones de testosterona se encuentran asociados a la disminución de la masa ósea. Al igual que en la mujer, la osteoporosis en el hombre debe tratarse con suplementos de calcio y vitamina D. Recientemente se ha demostrado que el alendronato, un bisfosfonato ha tenido éxito para mejorar la densidad ósea y disminuir la incidencia de fracturas en el hombre. La terapia de reemplazo con andrógenos se espera tenga efecto benéfico sobre el hueso, pero se requieren estudios clínicos controlados que lo comprueben.

Comparative accuracy of glucose monitors

Background. Self-monitoring of blood glucose levels has become an important instrument for the management of patients with diabetes mellitus. Both patients and physicians expect that monitors will provide reliable results. Numerous environmental, physiologic, and operational factors can affects system performance, yielding results that are inaccurate or unpredictable. Methods. This study examined the effect of one factor -high altitude- on the performance of seven blood glucose monitoring systems. The following monitors were compared. two One Touch II; two One Touch Basic; two Reflolux II (Accu-Chec in the USA); two Glucometer 3; one Glucometer 2, and one Accutrend Alpha. Double blood glucose level values were compared with a cotrolled reference laboratory test values, which was unknown to the investigator until the end of the study because the study was double blind. Blood glucose values were obtained using each of the monitors in 200 patients; 150 with diabetes mellitus, and 50 healthy subjects. Results. The One Touch monitors were the only monitors that reported adjusted straight lines (Y0a+bX) that were very similar for all three techniques. In addition, these adjusted straight lines are those closest to the ideal line, Y=X. These same monitors were the only ones that did not reject the null hypothesis Ho: a=0. The relative deviation index at the 20 percent level was less than 3.5 percent for the One Touch II and One Touch Basic monitors; for the rest of the monitors the index was over 14 percent. The clinically accepted EGA region was similar for all study monitors. Conclusions. In conclusion, the One Touch II and One touch Basic Monitors showed greater accuracy in comparison to the other devices. The evaluation of the clinically acceptable region shows practical reliability for all of the monitor used

Effects of metformin on fibrinogen levels in obese patients with type 2 diabetes

Objetivo. Determinar los niveles de fibrinógeno en obesos con diabetes tipo 2 y valorar las potenciales modificaciones que induce la metformina. Métodos. Fue un estudio abierto, prospectivo, randomizado y comparativo que incluyó a 60 pacientes con diabetes tipo 2 obesos (IMC > 27) durante dos fases. La fase de pretratamiento fue de 4 semanas con un control con dieta. En la fase de tratamiento se les dividió en dos subgrupos de 30. Uno recibió una tableta de metformina de 850 mg, incrementándose la dosis a dos o tres tabletas de acuerdo al control metabólico; el otro subgrupo recibió insulina DNA-recombinante 24 U, subcutánea (dos tercios antes del desayuno y un tercio antes de la cena), ajustando la dosis de acuerdo a la respuesta. Como grupo control se incluyeron a 60 sujetos obesos no diabéticos, que durante las dos fases sólo recibieron dieta. Resultados. Los valores promedio de glucosa, fibriógeno y del índice de masa corporal (IMC) no cambiaron en la fase de pretratamiento de controles y diabéticos ni en la fase de tratamiento de los controles. En cambio los tres parámetros disminuyeron significativamente en el subgrupo de metformina (p < 0.001) y soló el de glucosa (p< 0.001) en el subgrupo de insulina. Conclusiones. La metformina, además de mejorar el control metabólico, demostró ser una buena alternativa para modificar favorablemente los niveles de fibrinógeno en pacientes con diabetes tipo 2

ACTH secreting pituitary microadenomas disclosed only by gadolinium DTPA enhanced MRI

Objetivo. Valorar la utilidad del Gd-DTPA y evidenciar aquellos microadenomas de la glándula hipófisis que no han sido demostrados por IRM sin su empleo en pacientes con enfermedad de Cushing. Método: se practicó a seis pacientes RM con y sin gadolinio para hacer evidente la tumoración, y los hallazgos fueron correlacionados con cirugía y confirmados por estudios inmunohistoquímico e histológico de la pieza quirúrgica. Resultados. En todos los casos postadministración del medio, en la RM se demostró una imagen hipodensa circunscrita que correspondía en forma precisa con la localización y extensión del tejido adenimatoso encontrado duarante la cirugía. La extirpación selectiva del microadenoma no tuvo éxito en la mejoría clínica y bioquímica en dos de los seis pacientes. Dichos casos no presentaron imagen residual hipodensa en la RM con Gd-DTPA en el postoperatorio. Conclusiones. Los resultados suguieren que la IRM con Gd-DTPA es un método útil para detectar microadenomas hipofisiarios no demostrables por IRM sin el medio de contraste; sin embargo, las alteraciones del tejido hipofisiario pueden extenderse más allá de la imagen anormal.

Utilidad de la prueba de reserva pancreática para determinar el tipo de diabetes y el tratamiento apropiado / Utility of the test of pancreatic reserve for to determine the type of diabetes and the appropriate treatment

Conocida la utilidad de la tolbutamida para cuantificar la reserva pancreática (RP), se decidió correlacionar el descenso de la glucemia con el incremento de la insulinemia durante la prueba de reserva pancreática (PRP) y, adem , averiguar si el resultado de ésta permite inferir el tipo de terapéutica y la dosis necesarias para un buen control. En la primera fase, 15 diabéticos (grupo I: dependientes de la insulina; grupo II; tratados con hipoglucemiantes orales; grupo III controlados sólo con dieta se sometieron por el método doble ciego y cruzado a la PRP con tolbutamida y luego con placebo; simultáneamente se midió la concentración de insulina. En el grupo I no fue significativa la diferencia entre fármaco y placebo pero si alcanzó validez estadística en los otros dos grupos y al comparar a éstos con el grupo I (p<0.05). En la segunda fase, 17 diabéticos (tipo I y II) se sometieron a la PRP y según el resultado de ésta, fueron tratados con dieta, hipoglucemiantes orales o insulina. Los nueve con valor <35 por 100 requirieron insulina y los ocho con valor mayor pudieron controlarse con dieta o hipoglucemiantes. Además se observó una relación entre el de la PRP y la dosis de medicamentos. Se concluye que la PRP permite diagnosticar el tipo de diabetes y determinar las pautas de esquema terapéutico; además es un recurso con alcance del médico general y del especialista .

Factores pronósticos en el tratamiento quirúrgico de adenomas hipofisarios / Prognostic factors in the surgical treatment of hypophyseal adenomas

Se analizaron los aspectos clínicos, radiológicos y de laboratorio que tuvieron relación con una evolución satisfactoria o desfavorable de 217 casos de adenomas hipofisarios después de operarlos. No mejoraron con la operación las afecciones visuales secundarias a atrofia óptica, el panhipopituitarismo y la diabetes insípida, y la mortalidad más alta ocurrió en los pacientes ciegos antes de operarse. En los acromegálicos, la deformidad faringeotraqueal y torácica con insuficiencia respiratoria aumentó el riesgo quirúrgico (anestésico) en forma considerable. En la enfermedad de Cushing se observaron hiperpigmentación de piel y mucosas y psicosis maniacodepresiva en los pacientes que tuvieron una evolución desfavorable, lo que contrastó con la evolución de los otros sin estos síntomas. El seguimiento con tomografia computarizada de cráneo puso de manifesto que los tumores con extensión parasillar y retrosillar rara vez pudieron extirparse en su totalidad, en tanto que así fue posible hacerlo totalmente con los adenomas situados en la línea media, independientemente de su tamaño. Los niveles basales de prolactina fueron proporcionales al tamaño del tumor, en tanto que los de las hormonas de crecimiento no lo fueron. La evolución fue mejor en pacientes con pruebas de TRH y bromocriptina positivas, y rara vez se lograron volver negativas después de la operación

Curacion e inactividad en acromegalia Resultados a largo plazo con cirugia o radioterapia. / Long term results of the treatment of acromegaly with surgery or radiotherapy

Con base en el analisis de los niveles basales de GH, PRL y TSH asi como en sus respuestas a la administracion de TRH, se evaluo la eficacia "terapeutica" de cirugia o radioterapia en 27 pacientes acromegalicos. Los resultados muestran que a largo plazo (48 meses), la eficacia de ambos procedimientos es semejante. Ademas, la persistencia de respuestas paradojicas en el subgrupo de pacientes TRH positivos: asi como los cambios de TSH y PRL en este y el subgrupo TRH negativos, permite cuestionar y evaluar los criterios de curacion e inactividad del sindrome