Multicentre, prospective, observational study investigating the most appropriate surgical option that can prevent the recurrence of primary spontaneous pneumothorax after surgery: the PATCH study, protocol.

INTRODUCTION: Thoracoscopic surgery is performed for refractory or recurrent primary spontaneous pneumothorax (PSP). To reduce postoperative recurrence, additional treatment is occasionally adopted during surgery after bulla resection. However, the most effective method has not been fully elucidated. Furthermore, the preference for additional treatment varies among countries, and its efficacy in preventing recurrence must be evaluated based on settings tailored for the conditions of a specific country. The number of registries collecting detailed data about PSP surgery is limited. Therefore, to address this issue, a prospective multicentre observational study was performed. METHODS AND ANALYSIS: This multicentre, prospective, observational study will enrol 450 participants aged between 16 and 40 years who initially underwent PSP surgery. Data about demographic characteristics, disease and family history, surgical details, and CT scan findings will be collected. Follow-up must be conducted until 3 years after surgery or in the event of recurrence, whichever came first. Patients without recurrence will undergo annual follow-up until 3 years after surgery. The primary outcome is the rate of recurrence within 2 years after surgery. A multivariate analysis will be performed to compare the efficacy of different surgical options. Then, adverse outcomes correlated with various treatments and the feasibility of treatment methods will be compared. ETHICS AND DISSEMINATION: This study was approved by the local ethics committee of all participating centres. The findings will be available in 2025, and they can be used as a basis for clinical decision-making regarding appropriate options for the initial PSP surgery. TRIAL REGISTRATION NUMBER: NCT04758143.

Prosaposin overexpression following kainic acid-induced neurotoxicity.

Because excessive glutamate release is believed to play a pivotal role in numerous neuropathological disorders, such as ischemia or seizure, we aimed to investigate whether intrinsic prosaposin (PS), a neuroprotective factor when supplied exogenously in vivo or in vitro, is up-regulated after the excitotoxicity induced by kainic acid (KA), a glutamate analog. In the present study, PS immunoreactivity and its mRNA expression in the hippocampal and cortical neurons showed significant increases on day 3 after KA injection, and high PS levels were maintained even after 3 weeks. The increase in PS, but not saposins, detected by immunoblot analysis suggests that the increase in PS-like immunoreactivity after KA injection was not due to an increase in saposins as lysosomal enzymes after neuronal damage, but rather to an increase in PS as a neurotrophic factor to improve neuronal survival. Furthermore, several neurons with slender nuclei inside/outside of the pyramidal layer showed more intense PS mRNA expression than other pyramidal neurons. Based on the results from double immunostaining using anti-PS and anti-GABA antibodies, these neurons were shown to be GABAergic interneurons in the extra- and intra-pyramidal layers. In the cerebral cortex, several large neurons in the V layer showed very intense PS mRNA expression 3 days after KA injection. The choroid plexus showed intense PS mRNA expression even in the normal rat, and the intensity increased significantly after KA injection. The present study indicates that inhibitory interneurons as well as stimulated hippocampal pyramidal and cortical neurons synthesize PS for neuronal survival, and the choroid plexus is highly activated to synthesize PS, which may prevent neurons from excitotoxic neuronal damage. To the best of our knowledge, this is the first study that demonstrates axonal transport and increased production of neurotrophic factor PS after KA injection.