Medial Septal Glutamatergic Neurons Modulate States of Consciousness during Sevoflurane Anesthesia in Mice.

BACKGROUND: Multiple neural structures involved in maintaining wakefulness have been found to promote arousal from general anesthesia. The medial septum is a critical region that modulates arousal behavior. This study hypothesized that glutamatergic neurons in the medial septum play a crucial role in regulating states of consciousness during sevoflurane general anesthesia. METHODS: Adult male mice were used in this study. The effects of sevoflurane anesthesia on neuronal activity were determined by fiber photometry. Lesions and chemogenetic manipulations were used to study the effects of the altered activity of medial septal glutamatergic neurons on anesthesia induction, emergence, and sensitivity to sevoflurane. Optogenetic stimulation was used to observe the role of acute activation of medial septal glutamatergic neurons on cortical activity and behavioral changes during sevoflurane-induced continuous steady state of general anesthesia and burst suppression state. RESULTS: The authors found that medial septal glutamatergic neuronal activity decreased during sevoflurane anesthesia induction and recovered in the early period of emergence. Chemogenetic activation of medial septal glutamatergic neurons prolonged the induction time (mean ± SD, hM3Dq-clozapine N-oxide vs. hM3Dq-saline, 297.5 ± 60.1 s vs. 229.4 ± 29.9 s, P < 0.001, n = 11) and decreased the emergence time (53.2 ± 11.8 s vs. 77.5 ± 33.5 s, P = 0.025, n = 11). Lesions or chemogenetic inhibition of these neurons produced the opposite effects. During steady state of general anesthesia and deep anesthesia-induced burst suppression state, acute optogenetic activation of medial septal glutamatergic neurons induced cortical activation and behavioral emergence. CONCLUSIONS: The study findings reveal that activation of medial septal glutamatergic neurons has arousal-promoting effects during sevoflurane anesthesia in male mice. The activation of these neurons prolongs the induction and accelerates the emergence of anesthesia.

Imaging asparaginyl endopeptidase (AEP) in the live brain as a biomarker for Alzheimer's disease.

BACKGROUND: Discovery of early-stage biomarkers is a long-sought goal of Alzheimer's disease (AD) diagnosis. Age is the greatest risk factor for most AD and accumulating evidence suggests that age-dependent elevation of asparaginyl endopeptidase (AEP) in the brain may represent a new biological marker for predicting AD. However, this speculation remains to be explored with an appropriate assay method because mammalian AEP exists in many organs and the level of AEP in body fluid isn't proportional to its concentration in brain parenchyma. To this end, we here modified gold nanoparticle (AuNPs) into an AEP-responsive imaging probe and choose transgenic APPswe/PS1dE9 (APP/PS1) mice as an animal model of AD. Our aim is to determine whether imaging of brain AEP can be used to predict AD pathology. RESULTS: This AEP-responsive imaging probe AuNPs-Cy5.5-A&C consisted of two particles, AuNPs-Cy5.5-AK and AuNPs-Cy5.5-CABT, which were respectively modified with Ala-Ala-Asn-Cys-Lys (AK) and 2-cyano-6-aminobenzothiazole (CABT). We showed that AuNPs-Cy5.5-A&C could be selectively activated by AEP to aggregate and emit strong fluorescence. Moreover, AuNPs-Cy5.5-A&C displayed a general applicability in various cell lines and its florescence intensity correlated well with AEP activity in these cells. In the brain of APP/PS1 transgenic mice , AEP activity was increased at an early disease stage of AD that precedes formation of senile plaques and cognitive impairment. Pharmacological inhibition of AEP with δ-secretase inhibitor 11 (10 mg kg-1, p.o.) reduced production of ß-amyloid (Aß) and ameliorated memory loss. Therefore, elevation of AEP is an early sign of AD onset. Finally, we showed that live animal imaging with this AEP-responsive probe could monitor the up-regulated AEP in the brain of APP/PS1 mice. CONCLUSIONS: The current work provided a proof of concept that assessment of brain AEP activity by in vivo imaging assay is a potential biomarker for early diagnosis of AD.

"Angioplasty-First" Approach for Limb Salvage in Asian Patients with Critical Limb Ischemia: Outcomes from 3,303 Angioplasties on 2,402 Limbs in a Single Tertiary Hospital.

PURPOSE: To review outcomes of patients with critical limb ischemia (CLI) who underwent conventional percutaneous transluminal angioplasty (PTA) as first-line treatment for revascularization. MATERIALS AND METHODS: Retrospective review of 3,303 angioplasty procedures on 2,402 limbs in 1,968 patients with CLI was conducted. Mean patient age was 68 years ± 11, and 1,057 patients (54%) were male. Diabetes mellitus (DM) was present in 1,736 patients (88%), and end-stage renal disease (ESRD) in 579 (29%). A majority of patients (90%) had tissue loss. Limb salvage rates were generated by Kaplan-Meier plot. Univariate and multivariate Cox regression analysis was conducted to investigate associations between clinical predictors and time-to-event outcome. RESULTS: Limb salvage rates at 1, 3, 5, and 10 years were 75%, 73%, 72%, and 62%, respectively, and overall survival rates were 79%, 64%, 56%, and 34%, respectively. In multivariable Cox regression analysis with the outcome of major amputation, significant predictors included age < 69 years (P = .032), Malay race (P = .029), DM (P < .001), history of cerebral vascular disease (P = .003), ESRD (P < .001), Rutherford classification (P = .042), repeat intervention (P = .034), and number of straight-line flows (P < .001) and plantar arch integrity (P < .001) on completion angiography. Significant associations with mortality were age < 69 years (P < .001), male sex (P = .030), Malay race (P = .027), history of ischemic heart disease (P < .001), ESRD (P < .001), and repeat intervention (P < .001). CONCLUSIONS: PTA as first-line revascularization for patients with CLI is safe and effective. Further studies are suggested to validate the outcome predictive model.