Acción de la hipervitaminosis A en el germen dentario de fetos de rata: estudio histológico y morfométrico / Action of hypervitaminosis a on the tooth germ of rat fetuses: histologic and morphometric study

El presente trabajo tiene por objetivo caracterizar histológica y morfométricamente, las alteraciones de los epitelios externo e interno del órgano del esmalte, de molares de fetos de ratas inyectadas con una dosis excesiva de vitamina A, durante el período teratogénico (DG10). El análisis histológico de los fetos de los grupos tratados, reveló que los epitelios externo e interno del órgano del esmalte estaban constituídos por células más bajas, con núcleos de menor tamaño. El estudio morfométrico demostró que los animales tratados con exceso de vitamina A, poseían núcleos más pequeños y con alteraciones de forma en los epitelios del órgano del esmalte. Los resultados obtenidos sugieren que la vitamina A en exceso actua en la odontogénesis y morfogénesis de la cabeza, provocando el nacimiento de fetos malformados

Impacto de las afecciones genéticas en lactantes desnutridos secundarios / Impact of genetic disorders among infants with secondary undernutrition

El control de las tasas de desnutrición primaria en Chile ha permitido la detección de un número creciente de lactantes con desnutrición secundaria, como lo confirma esta investigación realizada entre los 1.542 lactantes ingresados a un centro de recuperación y estudio de desnutridos secundarios, en el período comprendido entre enero de 1985 y diciembre de 1990. Cada uno de los pacientes fue asignado, de acuerdo con el diagnóstico de ingreso, a una de las categorías de la clasificación de Hall, según la cual las afecciones genéticas y las malformaciones congénitas eran responsables de 40,1% de los ingresos (afecciones ciertamente genéticas 12,9%, enfermedades poligénicas-multifactoriales 15,8%, anomalías del desarrollo 9,1%, causadas por teratógenos 2,3%). El hallazgo de un número considerable de anomalías cromosómicas (n:54), en mayor proporción que en la población general, sugiere la conveniencia de realizar estudios citogenéticos en los pacientes con desnutrición secundaria y dismorfias o retardo psicomotor

Daño hepático inducido por drogas

Drug induced liver disease is responsible of 5 percent of hospital admissions for jaundice in USA, and 10 percent of acute hepatitis in France and North Europe. In addition, 20 to 50 percent of the cases of fulminant hepatic failure in USA are due to drugs. Tradicionally drug induced liver disease has been divided in two groups : 1. Non predictable toxicity (idiosyncratic reaction). 2. Predictable toxicity (Intrinsec toxicity). From the clinical point of view, most of the patients present jaundice associated with elevation of aminotransferases and alkaline phosphatase. However, some patients presents acute liver failure and death. Te duration of illness permit another classification in two groups : acute, frequently characterized by microvesicular steatosis; a picture similar to acute viral hepatitis or biliary obstruction (cholestasic jaundice) with elevated alkaline phosphatase and pruritus. Chronic, manifested by different presentations such as acute hepatitis, chronic hepatitis, (autoimmune), sclerosing cholangitis, phospholipidosis and non cirrhotic or cirrhotic portal hypertension. Histologically drug toxicity can induce the following morphologic changes : a) Pure cholestasis more frequently seen with estrogens. b) Viral hepatitis like. c) Fulminant hepatic failure more commonly seen with halotane, acetaminophen, phenytoin and methyldopa shows multilobular necrosis frequently asssociated with hypersensitivity features (fever, pruritus, eosinofilia)...

Prescripción de medicamentos en enfermos hepáticos

A common problem in patients with liver disease, is chronic administration of drugs. The presence of abnormalities in hepatic metabolism and the splanchnic circulation, makes drug presciption a very special situation. Cirrhosis induces a significant diminituion of the portal venous flow which is compensated by the hepatic artery. The hepatic clearance of drugs depends directly of the hepatic flow and the hepatic extraction of each medication. Consequently, hepatic clearance is equal to the hepatic flow multiplied by the hepatic extraction. drugs efficiently removed by the liver can be affected by a reduction of liver flow, good examples are : lidocaine, nitroglycerin, isosorbide dinitrate, propranolol, verapamil and indocyanine green. This group of medications have a very low bioavailability. In the normal situation the liver removes all of the compound in the first pass, leaving a small amount to the systemic circulation. Tha capacity to remove a drug when the liver flow is not the limiting factor has been defined as intrinsec clearance. High extraction drugs have a high intrinsec clearence and their bioavailability is also very high in cirrhosis. The main two reasons are : a reduced intrinsec clearence and the presence of spontaneous porta-systemic shunts, that derived blood from the splanchnic circulation directly into the systemic one bypassing the liver. As a result of these abnormalities a reduction of the dosage is usually neccesary. A clasic example is propranolol in the treatment of portal hypertension, where dosage of 20-60 mg are usually sufficient, in contrast with higher dosage in the treatment of arterial hypertension. In general drugs that depends on phase I of hepatic metabolism (oxidation, desmetylation) are more affected as far a biotransformation than those depending on phase II (glucuronidation). The impact of this reduction will be more important for low extraction drugs nor affected by changes in the hepatic flow. Examples of these are : aminophyline, caffeine and aminopyrine. Other factors such as cholestasis, low albumin levels and a special sensitivity to the toxic effects of some compounds by some organs such as the stomach (non steroidal anti-inflammatories), kidney (aminoglycosides), and brain (benzodiazepines), are of paramount importance.