Thiamine Deficiency Increases Intrinsic Excitability of Mouse Cerebellar Purkinje Cells.

Thiamine deficiency is associated with cerebellar dysfunction; however, the consequences of thiamine deficiency on the electrophysiological properties of cerebellar Purkinje cells are poorly understood. Here, we evaluated these parameters in brain slices containing cerebellar vermis. Adult mice were maintained for 12-13 days on a thiamine-free diet coupled with daily injections of pyrithiamine, an inhibitor of thiamine phosphorylation. Morphological analysis revealed a 20% reduction in Purkinje cell and nuclear volume in thiamine-deficient animals compared to feeding-matched controls, with no reduction in cell count. Under whole-cell current clamp, thiamine-deficient Purkinje cells required significantly less current injection to fire an action potential. This reduction in rheobase was not due to a change in voltage threshold. Rather, thiamine-deficient neurons presented significantly higher input resistance specifically in the voltage range just below threshold, which increases their sensitivity to current at these critical membrane potentials. In addition, thiamine deficiency caused a significant decrease in the amplitude of the action potential afterhyperpolarization, broadened the action potential, and decreased the current threshold for depolarization block. When thiamine-deficient animals were allowed to recover for 1 week on a normal diet, rheobase, threshold, action potential half-width, and depolarization block threshold were no longer different from controls. We conclude that thiamine deficiency causes significant but reversible changes to the electrophysiology properties of Purkinje cells prior to pathological morphological alterations or cell loss. Thus, the data obtained in the present study indicate that increased excitability of Purkinje cells may represent a leading indicator of cerebellar dysfunction caused by lack of thiamine.

Persistencia de epónimos en terminologia histologica / Eponyms persistence in terminologia histologica

El uso de epónimos aún es una práctica frecuentemente utilizada entre médicos clínicos y académicos para referirse a las distintas estructuras en histología. A pesar de los esfuerzos por parte de la comunidad morfológica por desarraigarlos del lenguaje médico, hoy en día se encuentran, inclusive presentes en Terminologia Histologica, tal como en los casos de Schannocytus (H2.00.06.2.02003) referente a la Célula de Schwann; Complexus golgiensis (H1.00.01.3.0146) referente al Aparato de Golgi, Cellula panethensis (H3.04.03.0.00017) referente a la Célula de Paneth, y Neuron purkinjense (H3.11.03.4.01015) referente a la Neurona de Purkinje, que aluden a los investigadores Theodor Schwann, Camillo Golgi, Joseph Paneth y Jan Evangelista Purkinje, respectivamente. El objetivo del presente estudio fue realizar un análisis de los términos antes nombrados desde un punto de vista lingüístico y proponer nuevas denominaciones, siguiendo los parámetros establecidos en la Terminología, en la cual los nombres de las estructuras deben tener un valor informativo, estar escritos en latín como lengua base y eliminar el uso de los epónimos. Los términos analizados, se refieren a nombres de células u organelos frecuentemente utilizados en textos educativos, sin embargo, son poco descriptivos, muchos de ellos con raíces netamente griegas y otros neologismos, cuyas denominaciones, por consenso y en honor a investigadores connotados han perdurado en el tiempo. Proponemos modificaciones con respecto a su denominación, así como a sus derivados, utilizando términos procedentes del latín. En resumen, pretendemos que con estos antecedentes iniciales puedan entregarse argumentos que permitan seguir unificando criterios y que ellos puedan ser considerados por los expertos que conforman el Programa Federativo Internacional de Terminología Anatómica y, como bien se señala, permitir el establecimiento de diálogo con los miembros de la Federación Internacional de Asociaciones de Anatomistas e ir mejorando la comunicación científica entre los diferentes actores de las ciencias morfológicas.

Eponyms are still frequently used among clinicians and scholars to refer to the various structures in histology. Despite efforts by the morphological community to eradicate eponyms from medical language, nowadays they are practical, and even present in Terminologia Histologica (TH), such as in the case of Schannocytus (H2.00.06.2.02003) concerning the term Schwann cell; Complexus golgiensis (H1.00.01.3.0146) relating to the Golgi apparatus, Cellula panethensis (H3.04.03.0.00017) concerning the Paneth cell and Neuron purkinjense (H3.11.03.4.01015), the term Purkinje neuron which refers to researchers Theodor Schwann, Camillo Golgi, Joseph Paneth and Jan Evangelist Purkinje, respectively. The aim of this study was to conduct an analysis of these terms from a linguistic point of view and propose new Latin names, following guidelines established in the terminology wherein the names of structures must, have an informative value, be written in Latin as a base language, and eliminate the use of eponyms. The terms analyzed, refer to cells or organelles names frequently used, they have limited descriptive value, many with purely Greek roots and other neologisms, which names have endured over time in honor of renowned researchers. Using terms from Larin, we propose modifications with respect to classification and derivatives. In conclusion, we hope that with this introduction, the information to consolidate standards will be considered by the experts of the Federal International Committee on Anatomical Terminology and further, initiate a dialogue with International Federation of Associations of Anatomists members, while encouraging ongoing communication between the various players of morphological sciences.