Two Different Tracts and Origin of Pyriform Sinus Fistula.

OBJECTIVE: Suppurative acute thyroiditis is caused by pyriform sinus fistula (PSF), and PSF frequently elicits deep neck abscess. However, complete fistulectomy is the ideal management of PSF, and studies on surgical findings of PSF are exceedingly rare. This study aimed to reveal the origins of PSF, each route, and clinical presentation. METHODS: This is a multicenter study. We have conducted 19 complete fistulectomies of PSF in Japan, analyzed routes of the fistulas, estimated the origins, and investigated their histological and clinical findings. RESULTS: No recurrence was observed in all cases. Five of 12 cases showed thymic and/or parathyroid tissues around the fistulas, passing inside the inferior horn of thyroid cartilage, were regarded as having 3rd pouch origin, and tended to have low frequency of severe deep neck abscess. The remaining 7 cases originated from the 4th pouch running outside of the horn and showed frequent severe infection. CONCLUSION: PSF have 2 different routes depending on their generation and may present different clinical manifestations.

[Optical Erasure of the Synaptic Ensemble that Underlies Learning and Memory].

Dentritic spines are small membrane protrusions. Their regulation is thought to be important for memory storage, but the links between dentric spines and memory have been largely correlational because of a luck of techniques for manipulating individual spines. To overcome this problem, we have developed a novel synaptic optoprobe, AS-PaRac1, which is unique not only because it specifically labels recently potentiated spines, but also because it becomes possible to selectively shrink spines containing AS-PaRac1. This indicates that AS-PaRac1 can be use to specifically visualize the recently "written spines" and that the erasure of these spines is possible upon excitation with blue light. Using in vivo two-photon imaging, synaptic potentiation was visualized during active remodeling of the neocortex. Upon learning a motor skill, AS-PaRac1 expression was induced in a relatively small number of neurons, in which approximately 8% of spines were tagged by AS-PaRac1. The labeled spines were broadly distributed throughout the dendritic tree. Excitation with blue light induced shrinkage of learning related spines and disrupted the acquired motor learning. In contrast, the erasure of a similar number of learning-irrelevant spines did not affect task performance. This novel light-dependent tool will open up new areas of memory research, and will additionally shed light on the neural networks that determine who we are.

Role of dopamine on functional recovery in the contralateral hemisphere after focal stroke in the somatosensory cortex.

Functional recovery after a stroke is important for patients' quality of life. Not only medical care during the acute phase, but also rehabilitation during the chronic phase after a stroke is important. However, the mechanisms underlying functional recovery, particularly the chronic phase after stroke, are still not fully understood. Thus, further basic study on brain after focal stroke is necessary. In this study, we found that the concentration of dopamine (DA) increased during first week after a stroke in the hemisphere contralateral in the site of stroke by in vivo microdialysis. When we applied haloperidol (HPD), a potent DA receptor blocker, functional recovery was inhibited. Interestingly, administration of aripiprazole (ARP), a novel partial agonist of the DA receptor, during the chronic phase improved the remodeling of neuronal circuits in somatosensory cortex (SSC). These findings indicate that the DAergic system play a critical role in functional compensation by the non-infarcted hemisphere after a focal stroke in SSC. It is also revealed that administration of HPD/ARP to stroke patients affects functional recovery after a stroke, and stimulation of the DAergic system during the chronic phase of stroke potentially benefits stroke patients.