Intraneuronal ß-amyloid impaired mitochondrial proteostasis through the impact on LONP1.

Mitochondrial dysfunction plays a critical role in the pathogenesis of Alzheimer's disease (AD). Mitochondrial proteostasis regulated by chaperones and proteases in each compartment of mitochondria is critical for mitochondrial function, and it is suspected that mitochondrial proteostasis deficits may be involved in mitochondrial dysfunction in AD. In this study, we identified LONP1, an ATP-dependent protease in the matrix, as a top Aß42 interacting mitochondrial protein through an unbiased screening and found significantly decreased LONP1 expression and extensive mitochondrial proteostasis deficits in AD experimental models both in vitro and in vivo, as well as in the brain of AD patients. Impaired METTL3-m6A signaling contributed at least in part to Aß42-induced LONP1 reduction. Moreover, Aß42 interaction with LONP1 impaired the assembly and protease activity of LONP1 both in vitro and in vivo. Importantly, LONP1 knockdown caused mitochondrial proteostasis deficits and dysfunction in neurons, while restored expression of LONP1 in neurons expressing intracellular Aß and in the brain of CRND8 APP transgenic mice rescued Aß-induced mitochondrial deficits and cognitive deficits. These results demonstrated a critical role of LONP1 in disturbed mitochondrial proteostasis and mitochondrial dysfunction in AD and revealed a mechanism underlying intracellular Aß42-induced mitochondrial toxicity through its impact on LONP1 and mitochondrial proteostasis.

High-Precision Atom Interferometer-Based Dynamic Gravimeter Measurement by Eliminating the Cross-Coupling Effect.

A dynamic gravimeter with an atomic interferometer (AI) can perform absolute gravity measurements with high precision. AI-based dynamic gravity measurement is a type of joint measurement that uses an AI sensor and a classical accelerometer. The coupling of the two sensors may degrade the measurement precision. In this study, we analyzed the cross-coupling effect and introduced a recovery vector to suppress this effect. We improved the phase noise of the interference fringe by a factor of 1.9 by performing marine gravity measurements using an AI-based gravimeter and optimizing the recovery vector. Marine gravity measurements were performed, and high gravity measurement precision was achieved. The external and inner coincidence accuracies of the gravity measurement were ±0.42 mGal and ±0.46 mGal after optimizing the cross-coupling effect, which was improved by factors of 4.18 and 4.21 compared to the cases without optimization.

Accuracy Improvement of a Compact 85Rb Atom Gravimeter by Suppressing Laser Crosstalk and Light Shift.

We design and implement a compact 85Rb atom gravimeter (AG). The diameter of the sensor head is 35 cm and the height is 65 cm; the optical and electronic systems are installed in four standard 3U cabinets. The measurement accuracy of this AG is improved by suppress laser crosstalk and light shift. In addition, the angle of the Raman laser reflector is adjusted and locked, and the attitude of the sensing head is automatically adjusted, and the vibration noise is also compensated. The comparison measurement results between this AG and the superconducting gravimeter indicate that its long-term stability is 0.65 µGal @50000 s.

Mfn2 Overexpression Attenuates MPTP Neurotoxicity In Vivo.

Mitochondrial dysfunction represents a critical event in the pathogenesis of Parkinson's disease (PD). Increasing evidence demonstrates that disturbed mitochondrial dynamics and quality control play an important role in mitochondrial dysfunction in PD. Our previous study demonstrated that MPP+ induces mitochondrial fragmentation in vitro. In this study, we aimed to assess whether blocking MPTP-induced mitochondrial fragmentation by overexpressing Mfn2 affords neuroprotection in vivo. We found that the significant loss of dopaminergic neurons in the substantia nigra (SN) induced by MPTP treatment, as seen in wild-type littermate control mice, was almost completely blocked in mice overexpressing Mfn2 (hMfn2 mice). The dramatic reduction in dopamine neuronal fibers and dopamine levels in the striatum caused by MPTP administration was also partially inhibited in hMfn2 mice. MPTP-induced oxidative stress and inflammatory response in the SN and striatum were significantly alleviated in hMfn2 mice. The impairment of motor function caused by MPTP was also blocked in hMfn2 mice. Overall, our work demonstrates that restoration of mitochondrial dynamics by Mfn2 overexpression protects against neuronal toxicity in an MPTP-based PD mouse model, which supports the modulation of mitochondrial dynamics as a potential therapeutic target for PD treatment.

A conserved retromer sorting motif is essential for mitochondrial DLP1 recycling by VPS35 in Parkinson's disease model.

Impaired mitochondria dynamics and quality control are involved in mitochondrial dysfunction and pathogenesis of Parkinson's disease (PD). VPS35 mutations cause autosomal dominant PD and we recently demonstrated that fPD-associated VPS35 mutants can cause mitochondrial fragmentation through enhanced VPS35-DLP1 interaction. In this study, we focused on the specific sites on DLP1 responsible for the VPS35-DLP1 interaction. A highly conserved FLV motif was identified in the C-terminus of DLP1, mutation of which significantly reduced VPS35-DLP1 interaction. A decoy peptide design based on this FLV motif could block the VPS35-DLP1 interaction and inhibit the recycling of mitochondrial DLP1 complexes. Importantly, VPS35 D620N mutant-induced mitochondrial fragmentation and respiratory deficits could be rescued by the treatment of this decoy peptide in both M17 cells overexpressing D620N or PD fibroblasts bearing this mutation. Overall, our results lend further support to the notion that VPS35-DLP1 interaction is key to the retromer-dependent recycling of mitochondrial DLP1 complex during mitochondrial fission and provide a novel therapeutic target to control excessive fission and associated mitochondrial deficits.

Inhibition of mitochondrial fragmentation protects against Alzheimer's disease in rodent model.

Mitochondrial dysfunction is an early prominent feature in susceptible neurons in the brain of patients with Alzheimer's disease, which likely plays a critical role in the pathogenesis of disease. Increasing evidence suggests abnormal mitochondrial dynamics as important underlying mechanisms. In this study, we characterized marked mitochondrial fragmentation and abnormal mitochondrial distribution in the pyramidal neurons along with mitochondrial dysfunction in the brain of Alzheimer's disease mouse model CRND8 as early as 3 months of age before the accumulation of amyloid pathology. To establish the pathogenic significance of these abnormalities, we inhibited mitochondrial fragmentation by the treatment of mitochondrial division inhibitor 1 (mdivi-1), a mitochondrial fission inhibitor. Mdivi-1 treatment could rescue both mitochondrial fragmentation and distribution deficits and improve mitochondrial function in the CRND8 neurons both in vitro and in vivo. More importantly, the amelioration of mitochondrial dynamic deficits by mdivi-1 treatment markedly decreased extracellular amyloid deposition and Aß1-42/Aß1-40 ratio, prevented the development of cognitive deficits in Y-maze test and improved synaptic parameters. Our findings support the notion that abnormal mitochondrial dynamics plays an early and causal role in mitochondrial dysfunction and Alzheimer's disease-related pathological and cognitive impairments in vivo and indicate the potential value of restoration of mitochondrial dynamics as an innovative therapeutic strategy for Alzheimer's disease.

HDL mimetic peptides affect apolipoprotein E metabolism: equal supplement or functional enhancer?: An Editorial for 'High-density lipoprotein mimetic peptide 4F mitigates amyloid-ß-induced inhibition of apolipoprotein E secretion and lipidation in primary astrocytes and microglia' on page 647.

ε4 allele of ApoE is the strongest genetic risk factor for late onset Alzheimer's disease (AD). Supplementation of ApoE proteins or mimetics has been pursued for drug developments against AD. A very low-density lipoprotein (HDL) mimetic peptide 4F was shown to alleviate AD-related deficits in APP transgenic mice, and this editorial highlights a study by Chernick et al. who use both mouse and human neuroglial cells to explore the mechanism underlying beneficial effects of this peptide. The authors demonstrate that 4F peptide significantly increased the secretion and lipidation of ApoE in the absence and presence of Aß independent of de novo transcription/translation, but requiring ABCA1 and the integrity of the secretory pathway between ER and Golgi. This study reveals a novel mechanism of HDL mimetic peptide as a functional ApoE enhancer and support further development of ApoA-I 4F peptide as effective ApoE modulating agents against AD.

Motor-Coordinative and Cognitive Dysfunction Caused by Mutant TDP-43 Could Be Reversed by Inhibiting Its Mitochondrial Localization.

Dominant missense mutations in TAR DNA-binding protein 43 (TDP-43) cause amyotrophic lateral sclerosis (ALS), and the cytoplasmic accumulation of TDP-43 represents a pathological hallmark in ALS and frontotemporal lobar degeneration (FTD). Behavioral investigation of the transgenic mouse model expressing the disease-causing human TDP-43 M337V mutant (TDP-43M337V mice) is encumbered by premature death in homozygous transgenic mice and a reported lack of phenotype assessed by tail elevation and footprint in hemizygous transgenic mice. Here, using a battery of motor-coordinative and cognitive tests, we report robust motor-coordinative and cognitive deficits in hemizygous TDP-43M337V mice by 8 months of age. After 12 months of age, cortical neurons are significantly affected by the mild expression of mutant TDP-43, characterized by cytoplasmic TDP-43 mislocalization, mitochondrial dysfunction, and neuronal loss. Compared with age-matched non-transgenic mice, TDP-43M337V mice demonstrate a similar expression of total TDP-43 but higher levels of TDP-43 in mitochondria. Interestingly, a TDP-43 mitochondrial localization inhibitory peptide abolishes cytoplasmic TDP-43 accumulation, restores mitochondrial function, prevents neuronal loss, and alleviates motor-coordinative and cognitive deficits in adult hemizygous TDP-43M337V mice. Thus, this study suggests hemizygous TDP-43M337V mice as a useful animal model to study TDP-43 toxicity and further consolidates mitochondrial TDP-43 as a novel therapeutic target for TDP-43-linked neurodegenerative diseases.

Glutaredoxin deficiency exacerbates neurodegeneration in C. elegans models of Parkinson's disease.

Parkinson's disease (PD) is characterized by selective degeneration of dopaminergic neurons. Although the etiology of PD remains incompletely understood, oxidative stress has been implicated as an important contributor in the development of PD. Oxidative stress can lead to oxidation and functional perturbation of proteins critical to neuronal survival. Glutaredoxin 1 (Grx1) is an evolutionally conserved antioxidant enzyme that repairs protein oxidation by reversing the oxidative modification of cysteine known as S-glutathionylation. We aimed to explore the regulatory role of Grx1 in PD. We first examined the levels of Grx1 in postmortem midbrain samples from PD patients, and observed that Grx1 content is decreased in PD, specifically within the dopaminergic neurons. We subsequently investigated the potential role of Grx1 deficiency in PD pathogenesis by examining the consequences of loss of the Caenorhabditis elegans Grx1 homolog in well-established worm models of familial PD caused by overexpression of pathogenic human LRRK2 mutants G2019S or R1441C. We found that loss of the Grx1 homolog led to significant exacerbation of the neurodegenerative phenotype in C. elegans overexpressing the human LRRK2 mutants. Re-expression in the dopaminergic neurons of the active, but not a catalytically inactive form of the Grx1 homolog rescued the exacerbated phenotype. Loss of the Grx1 homolog also exacerbated the neurodegenerative phenotype in other C. elegans models, including overexpression of human α-synuclein and overexpression of tyrosine hydroxylase (a model of sporadic PD). Therefore, our results reveal a novel neuroprotective role of glutaredoxin against dopaminergic neurodegeneration in models of familial and sporadic PD.

Parkinson's disease-associated pathogenic VPS35 mutation causes complex I deficits.

Defect in the complex I of the mitochondrial electron-transport chain is a characteristic of Parkinson's disease (PD) which is thought to play a critical role in the disease pathogenesis. Mutations in vacuolar protein sorting 35 (VPS35) cause autosomal dominant PD and we recently demonstrated that pathogenic VPS35 mutations cause mitochondrial damage through enhanced mitochondrial fragmentation. In this study, we aimed to determine whether pathogenic VPS35 mutation impacts the activity of complex I and its underlying mechanism. Indeed, VPS35 D620N mutation led to decreased enzymatic activity and respiratory defects in complex I and II in patient fibroblasts. While no changes in the expression of the complex I and II subunits were noted, the level of assembled complex I and II as well as the supercomplex was significantly reduced in D620N fibroblasts. Importantly, inhibition of mitochondrial fission rescued the contents of assembled complexes as well as the functional defects in complex I and II. Overall, these results suggest that VPS35 D620N mutation-induced excessive mitochondrial fission leads to the defects in the assembled complex I and supercomplex and causes bioenergetics deficits.

Mfn2 protects dopaminergic neurons exposed to paraquat both in vitro and in vivo: Implications for idiopathic Parkinson's disease.

Mitochondrial dynamics and quality control play a critical role in the maintenance of mitochondrial homeostasis and function. Pathogenic mutations of many genes associated with familial Parkinson's disease (PD) caused abnormal mitochondrial dynamics, suggesting a likely involvement of disturbed mitochondrial fission/fusion in the pathogenesis of PD. In this study, we focused on the potential role of mitochondrial fission/fusion in idiopathic PD patients and in neuronal cells and animals exposed to paraquat (PQ), a commonly used herbicide and PD-related neurotoxin, as models for idiopathic PD. Significantly increased expression of dynamin-like protein 1 (DLP1) and a trend towards reduced expression of Mfn1 and Mfn2 were noted in the substantia nigra tissues from idiopathic PD cases. Interestingly, PQ treatment led to similar changes in the expression of fission/fusion proteins both in vitro and in vivo which was accompanied by extensive mitochondrial fragmentation and mitochondrial dysfunction. Blockage of PQ-induced mitochondrial fragmentation by Mfn2 overexpression protected neurons against PQ-induced mitochondrial dysfunction in vitro. More importantly, PQ-induced oxidative damage and stress signaling as well as selective loss of dopaminergic (DA) neurons in the substantia nigra and axonal terminals in striatum was also inhibited in transgenic mice overexpressing hMfn2. Overall, our study demonstrated that disturbed mitochondrial dynamics mediates PQ-induced mitochondrial dysfunction and neurotoxicity both in vitro and in vivo and is also likely involved in the pathogenesis of idiopathic PD which make them a promising therapeutic target for PD treatment.

Regulation of DJ-1 by Glutaredoxin 1 in Vivo: Implications for Parkinson's Disease.

Parkinson's disease (PD) is the second most common neurodegenerative disease worldwide, caused by the degeneration of the dopaminergic neurons in the substantia nigra. Mutations in PARK7 (DJ-1) result in early onset autosomal recessive PD, and oxidative modification of DJ-1 has been reported to regulate the protective activity of DJ-1 in vitro. Glutathionylation is a prevalent redox modification of proteins resulting from the disulfide adduction of the glutathione moiety to a reactive cysteine-SH, and glutathionylation of specific proteins has been implicated in regulation of cell viability. Glutaredoxin 1 (Grx1) is the principal deglutathionylating enzyme within cells, and it has been reported to mediate protection of dopaminergic neurons in Caenorhabditis elegans; however many of the functional downstream targets of Grx1 in vivo remain unknown. Previously, DJ-1 protein content was shown to decrease concomitantly with diminution of Grx1 protein content in cell culture of model neurons (SH-SY5Y and Neuro-2A lines). In the current study we aimed to investigate the regulation of DJ-1 by Grx1 in vivo and characterize its glutathionylation in vitro. Here, with Grx(-/-) mice we provide show that Grx1 regulates protein levels of DJ-1 in vivo. Furthermore, with model neuronal cells (SH-SY5Y) we observed decreased DJ-1 protein content in response to treatment with known glutathionylating agents, and with isolated DJ-1 we identified two distinct sites of glutathionylation. Finally, we found that overexpression of DJ-1 in the dopaminergic neurons partly compensates for the loss of the Grx1 homologue in a C. elegans in vivo model of PD. Therefore, our results reveal a novel redox modification of DJ-1 and suggest a novel regulatory mechanism for DJ-1 content in vivo.

MFN2 couples glutamate excitotoxicity and mitochondrial dysfunction in motor neurons.

Mitochondrial dysfunction plays a central role in glutamate-evoked neuronal excitotoxicity, and mitochondrial fission/fusion dynamics are essential for mitochondrial morphology and function. Here, we establish a novel mechanistic linker among glutamate excitotoxicity, mitochondrial dynamics, and mitochondrial dysfunction in spinal cord motor neurons. Ca(2+)-dependent activation of the cysteine protease calpain in response to glutamate results in the degradation of a key mitochondrial outer membrane fusion regulator, mitofusin 2 (MFN2), and leads to MFN2-mediated mitochondrial fragmentation preceding glutamate-induced neuronal death. MFN2 deficiency impairs mitochondrial function, induces motor neuronal death, and renders motor neurons vulnerable to glutamate excitotoxicity. Conversely, MFN2 overexpression blocks glutamate-induced mitochondrial fragmentation, mitochondrial dysfunction, and/or neuronal death in spinal cord motor neurons both in vitro and in mice. The inhibition of calpain activation also alleviates glutamate-induced excitotoxicity of mitochondria and neurons. Overall, these results suggest that glutamate excitotoxicity causes mitochondrial dysfunction by impairing mitochondrial dynamics via calpain-mediated MFN2 degradation in motor neurons and thus present a molecular mechanism coupling glutamate excitotoxicity and mitochondrial dysfunction.

Oxidative stress and mitochondrial dysfunction in Alzheimer's disease.

Alzheimer's disease (AD) exhibits extensive oxidative stress throughout the body, being detected peripherally as well as associated with the vulnerable regions of the brain affected in disease. Abundant evidence not only demonstrates the full spectrum of oxidative damage to neuronal macromolecules, but also reveals the occurrence of oxidative events early in the course of the disease and prior to the formation of the pathology, which support an important role of oxidative stress in AD. As a disease of abnormal aging, AD demonstrates oxidative damage at levels that significantly surpass that of elderly controls, which suggests the involvement of additional factor(s). Structurally and functionally damaged mitochondria, which are more proficient at producing reactive oxygen species but less so in ATP, are also an early and prominent feature of the disease. Since mitochondria are also vulnerable to oxidative stress, it is likely that a vicious downward spiral involving the interactions between mitochondrial dysfunction and oxidative stress contributes to the initiation and/or amplification of reactive oxygen species that is critical to the pathogenesis of AD.

The ALS disease-associated mutant TDP-43 impairs mitochondrial dynamics and function in motor neurons.

Mutations in TDP-43 lead to familial ALS. Expanding evidence suggests that impaired mitochondrial dynamics likely contribute to the selective degeneration of motor neurons in SOD1-associated ALS. In this study, we investigated whether and how TDP-43 mutations might impact mitochondrial dynamics and function. We demonstrated that overexpression of wild-type TDP-43 resulted in reduced mitochondrial length and density in neurites of primary motor neurons, features further exacerbated by ALS-associated TDP-43 mutants Q331K and M337V. In contrast, suppression of TDP-43 resulted in significantly increased mitochondrial length and density in neurites, suggesting a specific role of TDP-43 in regulating mitochondrial dynamics. Surprisingly, both TDP-43 overexpression and suppression impaired mitochondrial movement. We further showed that abnormal localization of TDP-43 in cytoplasm induced substantial and widespread abnormal mitochondrial dynamics. TDP-43 co-localized with mitochondria in motor neurons and their colocalization was enhanced by ALS associated mutant. Importantly, co-expression of mitochondrial fusion protein mitofusin 2 (Mfn2) could abolish TDP-43 induced mitochondrial dynamics abnormalities and mitochondrial dysfunction. Taken together, these data suggest that mutant TDP-43 impairs mitochondrial dynamics through enhanced localization on mitochondria, which causes mitochondrial dysfunction. Therefore, abnormal mitochondrial dynamics is likely a common feature of ALS which could be potential new therapeutic targets to treat ALS.

[Analysis of surgical treatment with pectoralis major muscle flap for deep sternal infection after cardiac surgery: a case series of 189 patients].

OBJECTIVE: To analyze and summarize the clinical features and experience in surgical treatment of deep sternal infection (DSWI). METHODS: This was a retrospective study. From January 2008 to December 2013, 189 patients with secondary DSWI after cardiac surgery underwent the pectoralis major muscle flap transposition in our department. There were 116 male and 73 female patients. The mean age was (54 ± 21) years, the body mass index was (26. 1 ± 1. 3) kg/m2. The incidence of postoperation DSWI were after isolated coronary artery bypass grafting (CABG) in 93 patients, after other heart surgery plus CABG in 13 patients, after valve surgery in 47 patients, after thoracic aortic surgery in 16 patients, after congenital heart disease in 18 patients, and after cardiac injury in 2 patients. Clean patients' wound and extract secretions, clear the infection thoroughly by surgery and select antibiotics based on susceptibility results, and then repair the wound with appropriate muscle flap, place drain tube with negative pressure. Of all the 189 patients, 184 used isolate pectoralis, 1 used isolate rectus, and 4 used pectoralis plus rectus. RESULTS: The operative wounds of 179 patients were primary healing (94. 7%). Hospital discharge was postponed by 1 week for 7 patients, due to subcutaneous wound infection. Subcutaneous wound infection occurred again in 8 patients 1 week after hospital discharge, and their wounds healed after wound dressing. Nine patients (4. 7%) did not recover, due to residue of the sequestrum and costal chondritis, whom were later cured by undergoing a second treatment of debridement and pectoralis major muscle flap transposition. Eight patients died, in which 2 died of respiratory failure, 2 died of bacterial endocarditis with septicemia, 2 died of renal failure, 1 died of intraoperative bleeding leading to brain death and the 1 died of heart failure. The mortality rate was 4. 2% . The average length of postoperative hospital stay was (14 ± 5) days. The longest postoperative follow-up period was 40 months, the median time was 26 months, the follow-up rate was 83. 9% . Totally 179 patients were no-reinfected, 2 patients were reinfected because of artificial vascular rejection. CONCLUSION: To perform surgical debridement and then reconstruct the sternal defect with pectoralis major muscle flap actively for the patient is an effective measure to improve patient's survival rate.

Ionizing radiation causes increased tau phosphorylation in primary neurons.

Radiotherapy is the major treatment modality for primary and metastatic brain tumors which involves the exposure of brain to ionizing radiation. Ionizing radiation can induce various detrimental pathophysiological effects in the adult brain, and Alzheimer's disease and related neurodegenerative disorders are considered to be late effects of radiation. In this study, we investigated whether ionizing radiation causes changes in tau phosphorylation in cultured primary neurons similar to that in Alzheimer's disease. We demonstrated that exposure to 0.5 or 2 Gy γ rays causes increased phosphorylation of tau protein at several phosphorylation sites in a time- and dose-dependent manner. Consistently, we also found ionizing radiation causes increased activation of GSK3ß, c-Jun N-terminal kinase and extracellular signal-regulated kinase before radiation-induced increase in tau phosphorylation. Specific inhibitors of these kinases almost fully blocked radiation-induced tau phosphorylation. Our studies further revealed that oxidative stress plays an important role in ionizing radiation-induced tau phosphorylation, likely through the activation of c-Jun N-terminal kinase and extracellular signal-regulated kinase, but not GSK3ß. Overall, our studies suggest that ionizing radiation may cause increased risk for development of Alzheimer's disease by promoting abnormal tau phosphorylation.

Effective atomic number of paraspinal muscles is associated with acute vertebral fracture risk.

OBJECTIVES: To investigate the relations among effective atomic number (Zeff), density, and area of paraspinal muscles, volumetric BMD (vBMD), and acute vertebral fractures (VF) by using spectral base images (SBIs) and routine CT images. METHODS: A total of 223 patients (52 men and 171 women) with acute VF and seven hundred and seventy-six subjects (286 men and 390 women) without VF of at least 60 years were enrolled and underwent dual-layer detector CT scans. We quantified the cross-sectional area (paraSMA), density (paraSMD) and Zeff of paraspinal muscles by CT images and SBIs and measured vBMD of the lumbar spine by quantitative CT. RESULTS: Higher vBMD was associated with lower VF risk in both sexes (adjusted OR, 0.33 and 0.43). After adjusting for age and BMI, the associations of ParaSMD with VF were not significant in men, and in women the association was borderline significant (OR, 0.80; 95% CI, 0.64 to 1.00). However, higher Zeff of paraspinal muscles was associated with lower VF risk in men (adjusted OR, 0.59; 0.36 to 0.96) but not in women. The associations of all muscle indexes with VF were not significant after further adjusting for vBMD. CONCLUSIONS: A higher Zeff of paraspinal muscles is associated with lower VF risk in older men but not in older women. The density, area and Zeff of paraspinal muscles were not vBMD independent risk factors for acute VF. ADVANCES IN KNOWLEDGE: The effective atomic number of paraspinal muscles might be a potential marker for vertebral fracture risk prediction.

Bezafibrate confers neuroprotection in the 5xFAD mouse model of Alzheimer's disease.

Mitochondrial dysfunction plays an important role in the pathogenesis of Alzheimer's disease (AD), the most common neurodegenerative disease. Prior studies suggested impaired mitochondrial biogenesis likely contributes to mitochondrial dysfunction in AD. Bezafibrate, a peroxisome proliferator-activated receptor (PPAR) pan-agonist, has been shown to enhance mitochondrial biogenesis and increase oxidative phosphorylation capacity. In the present study, we investigated whether bezafibrate could rescue mitochondrial dysfunction and other AD-related deficits in 5xFAD mice. Bezafibrate was well tolerated by 5xFAD mice. Indeed, it rescued the expression of key mitochondrial proteins as well as mitochondrial dynamics and function in the brain of 5xFAD mice. Importantly, bezafibrate treatment led to significant improvement of cognitive/memory function in 5xFAD mice accompanied by alleviation of amyloid pathology and neuronal loss as well as reduced oxidative stress and neuroinflammation. Overall, this study suggests that bezafibrate improves mitochondrial function, mitigates neuroinflammation and improves cognitive functions in 5xFAD mice, thus supporting the notion that enhancing mitochondrial biogenesis/function is a promising therapeutic strategy for AD.

Which Predictor, SctO2 or SstO2, Is more Sensitive for Postoperative Cognitive Dysfunction in Spine Surgery: A Prospective Observational Study?

OBJECTIVE: Patients undergoing spinal surgery in the prone position may experience venous stasis, often resulting in edema in dependent areas of the body, including the head, and increased postoperative cognitive dysfunction (POCD). Not only does POCD present challenges for post-operative care and recovery, it can also cause permanent damage to the patient's brain and increase mortality and social costs. We aimed to clarify the incidence of POCD in patients with hypertension after prone spine surgery and to further determine the association between intraoperative somatic tissue oxygen saturation (SstO2)/cerebral tissue oxygen saturation (SctO2) and POCD. METHODS: Patients with hypertension scheduled for open prone spine surgery from January 2020 to April 2021 were included in this single-center, prospective, observational study. SctO2 and SstO2 were monitored by near-infrared spectroscopy continuously throughout the surgery. The primary outcome was POCD assessed using the Mini-Mental Status Examination (MMSE). The association of SstO2 and SctO2 with POCD was evaluated with unadjusted analyses and multivariable logistic regression. RESULTS: One hundred and one of 112 identified patients were included, 28 (27.8%) of whom developed POCD. None of the investigated SctO2 indices were predictive of POCD. However, the patients with POCD had greater decreases in intraoperative absolute SstO2 and relative SstO2 than the patients without POCD (P = 0.037, P = 0.036). Moreover, three SstO2 indices were associated with POCD, including a greater absolute SstO2 decrease (P = 0.021), a greater relative SstO2 decrease (P = 0.032), and a drop below 90% of the baseline SstO2 (P = 0.002), independent of ASA III status, preoperative platelets and postoperative sepsis. In addition, there was no correlation between intraoperative SctO2 and intraoperative SstO2 or between their respective absolute declines. CONCLUSION: Twenty-eight (27.7%) of 101 patients developed POCD in patients with hypertension undergoing prone spine surgery, and intraoperative SstO2 is associated with POCD, whereas SctO2 shows no association with POCD. This study may initially provide a valuable new approach to the prevention of POCD in this population.