RESUMO
An increase in L-arginine hemolymph concentration acts as a postingestion signal inhibiting Aplysia feeding. At physiological concentrations (a 10-µM increase over background), the inhibitory effect of L-arginine is too weak to block feeding in hungry animals. However, a 10-µM increase in L-arginine concentration acts along with another inhibitory stimulus, the sustained presence of food odor, to inhibit feeding after a period of access to food. A physiological concentration of L-arginine also blocked the excitatory effect of a stimulus enhancing feeding, pheromones secreted by mating conspecifics. High concentrations of L-arginine (2.5 mM) alone also inhibited ad libitum feeding. L-arginine is the substrate from which nitric oxide synthase (NOS) produces nitric oxide (NO). Both an NO donor and a 10-µM increase in L-arginine inhibited biting in response to a weak food stimulus. Treatment with NOS inhibitors initiated food-finding and biting in the absence of food, indicating that food initiates feeding against a background of tonic nitrergic inhibition. Increased feeding in response to blocking NOS is accompanied by firing of the metacerebral (MCC) neuron, a monitor of food arousal. The excitatory effect on the MCC of blocking NOS is indirect. The data suggest that L-arginine acts by amplifying NO synthesis, which acts as a background stimulus inhibiting feeding. Background modulation of neural activity and behavior by NO may also be present in other systems, but such modulation may be difficult to identify because its effects are evident only in the context of additional stimuli modulating behavior.
Assuntos
Aplysia/fisiologia , Arginina/farmacologia , Retroalimentação Fisiológica/efeitos dos fármacos , Comportamento Alimentar/efeitos dos fármacos , Óxido Nítrico/fisiologia , Animais , Aplysia/efeitos dos fármacos , Comportamento Animal/efeitos dos fármacos , Comportamento Animal/fisiologia , Relação Dose-Resposta a Droga , Retroalimentação Fisiológica/fisiologia , Comportamento Alimentar/fisiologia , Fome/fisiologia , Óxido Nítrico Sintase/fisiologia , Odorantes , Feromônios/fisiologiaRESUMO
O sangue de cordão umbilical e placentário (SCUP) é uma rica fonte de células-tronco (CT) hematopoéticas e é amplamente utilizado como substituto da medula óssea em casos de transplante. As células do SCUP possuem vantagens sobre as células da medula óssea (MO), principalmente por serem mais jovens e apresentarem maior taxa proliferativa. Além dos progenitores hematopoéticos, o sangue de cordão umbilical contém progenitores endoteliais e mesenquimais, sugerindo sua possível aplicação nos novos protocolos de terapia celular para diferentes tecidos. Na presente revisão, discutimos a importância do armazenamento do sangue de cordão umbilical autólogo e as pesquisas desenvolvidas para a sua aplicação em doenças degenerativas.
Umbilical Cord Blood is a rich source of hematopoietic stem cells widely used as a substitute of bone marrow (BM) in transplants. Cells from umbilical cord blood present advantages over BM cells, mainly as they are younger and a have higher proliferative rate. Besides hematopoietic stem cells, umbilical cord blood contains endothelial and mesenchymal progenitor cells, suggesting their possible application in cell therapy protocols for different tissues. In this paper, we discuss the importance of autologous umbilical cord blood storage and the research on stem cell transplantation for degenerative diseases.
Assuntos
Humanos , Terapia Baseada em Transplante de Células e Tecidos , Transplante de Células-Tronco de Sangue do Cordão Umbilical , Sangue Fetal , Células-Tronco Mesenquimais , Cordão UmbilicalRESUMO
Malignant sarcoma reaching a focal endometriosis is a rare condition. It cannot be distinguished from an endometrial sarcoma except in cases which are developped in extra-uterine endometriosis without uterus involvement. The case reported is a forty-seven old white woman with a sarcoma of the endometrial stroma reaching a Douglas focal endometriosis. Cases from literature are reviewed.