RESUMO
Light at night is an emergent problem for modern society. Rodents exposed to light at night develop a loss of circadian rhythms, which leads to increased adiposity, altered immune response, and increased growth of tumors. In female rats, constant light (LL) eliminates the estrous cycle leading to a state of persistent estrus. The suprachiasmatic nucleus (SCN) drives circadian rhythms, and it interacts with the neuroendocrine network necessary for reproductive function. Timed restricted feeding (RF) exerts a powerful entraining influence on the circadian system, and it can influence the SCN activity and can restore rhythmicity or accelerate re-entrainment in experimental conditions of shift work or jet lag. The present study explored RF in female rats exposed to LL, with the hypothesis that this cyclic condition can rescue or prevent the loss of daily rhythms and benefit the expression of the estrous cycle. Two different feeding schedules were explored: 1. A 12-h food/12-h fasting schedule applied to arrhythmic rats after 3 weeks in LL, visualized as a rescue strategy (LL + RFR, 3 weeks), or applied simultaneously with the first day of LL as a preventive strategy (LL + RFP, 6 weeks). 2. A 12-h window of food intake with food given in four distributed pulses (every 3 h), applied after 3 weeks in LL, as a rescue strategy (LL + PR, 3 weeks) or applied simultaneously with the first day of LL as a preventive strategy (LL + PP, 6 weeks). Here, we present evidence that scheduled feeding can drive daily rhythms of activity and temperature in rats exposed to LL. However, the protocol of distributed feeding pulses was more efficient to restore the day-night activity and core temperature as well as the c-Fos day-night change in the SCN. Likewise, the distributed feeding partially restored the estrous cycle and the ovary morphology under LL condition. Data here provided indicate that the 12-h feeding/12-h fasting window determines the rest-activity cycle and can benefit directly the circadian and reproductive function. Moreover, this effect is stronger when food is distributed along the 12 h of subjective night.
RESUMO
Background: Signet-ring cell lymphoma is a rare entity that simulates epithelial neoplasms, sarcomas and reactive histiocytes conditions. It represents a morphological variant of non-Hodgkin's lymphomas, its diagnosis can represent a challenge, therefore it should be considered in complementary studies. Objective: The aim of this work is to show a case with a very rare morphology and to emphasize the importance of awareness this entity and avoid mistakes in its diagnosis. Clinical case: We present the case of a 67-year-old man, who developed lymph node growths in the right armpit, neck, right groin, and submandibular region, with apparent involvement of the lungs and spleen; was diagnosed as diffuse large B cell lymphoma with signet-ring morphology, originated in the germinal center. Transmission electron microscopy study was carried out for a more precise characterization of the morphology. Unfortunately, the patient did not return for a follow-up consultation, so he did not start treatment and died 6 months after diagnosis. Conclusions: Lymphoma with the signet-ring phenotype is rare, and can occur in any type of non-Hodgkin lymphoma; however, this morphology is more commonly associated with carcinomas and, less frequently, with sarcomas, melanomas or reactive histiocytes conditions, therefore should be considered this entity together with the appropriate use of complementary studies for proper diagnosis.
Introducción: el linfoma con células en anillo de sello es una entidad poco frecuente y simuladora de neoplasias epiteliales, sarcomas y condiciones reactivas de histiocitos. Representa una variante morfológica de distintos linfomas no Hodgkin, por lo que su diagnóstico puede representar un desafío y debe ser considerado al realizar estudios complementarios. Objetivo: mostrar un caso con una morfología muy poco frecuente y recalcar la importancia de conocer esta entidad para no cometer errores en su diagnóstico. Caso clínico: se documenta el caso de un hombre de 67 años que desarrolló crecimientos ganglionares en axila derecha, cuello, ingle derecha, y región submandibular, con aparente afección en pulmones y bazo, que fue diagnosticado como linfoma B difuso de células grandes con morfología en anillo de sello, originado en el centro germinal. Se realizó estudio de microscopía electrónica de transmisión para una mejor caracterización de la morfología. Desafortunadamente el paciente no regresó a consulta de seguimiento, por lo que no inició tratamiento, falleció a los 6 meses posteriores al diagnóstico. Conclusiones: el linfoma con fenotipo en anillo de sello es poco frecuente, y puede presentarse en cualquier tipo de linfomas no Hodgkin; sin embargo, esta morfología es más comúnmente asociada a carcinomas y, en menor frecuencia, a sarcomas, melanomas o histiocitos reactivos, por lo que el considerar esta entidad junto con el uso adecuado de estudios complementarios es de gran importancia para su adecuado diagnóstico.