Targeting Astrocyte Signaling Alleviates Cerebrovascular and Synaptic Function Deficits in a Diet-Based Mouse Model of Small Cerebral Vessel Disease.

Despite the indispensable role that astrocytes play in the neurovascular unit, few studies have investigated the functional impact of astrocyte signaling in cognitive decline and dementia related to vascular pathology. Diet-mediated induction of hyperhomocysteinemia (HHcy) recapitulates numerous features of vascular contributions to cognitive impairment and dementia (VCID). Here, we used astrocyte targeting approaches to evaluate astrocyte Ca2+ dysregulation and the impact of aberrant astrocyte signaling on cerebrovascular dysfunction and synapse impairment in male and female HHcy diet mice. Two-photon imaging conducted in fully awake mice revealed activity-dependent Ca2+ dysregulation in barrel cortex astrocytes under HHcy. Stimulation of contralateral whiskers elicited larger Ca2+ transients in individual astrocytes of HHcy diet mice compared with control diet mice. However, evoked Ca2+ signaling across astrocyte networks was impaired in HHcy mice. HHcy also was associated with increased activation of the Ca2+/calcineurin-dependent transcription factor NFAT4, which has been linked previously to the reactive astrocyte phenotype and synapse dysfunction in amyloid and brain injury models. Targeting the NFAT inhibitor VIVIT to astrocytes, using adeno-associated virus vectors, led to reduced GFAP promoter activity in HHcy diet mice and improved functional hyperemia in arterioles and capillaries. VIVIT expression in astrocytes also preserved CA1 synaptic function and improved spontaneous alternation performance on the Y maze. Together, the results demonstrate that aberrant astrocyte signaling can impair the major functional properties of the neurovascular unit (i.e., cerebral vessel regulation and synaptic regulation) and may therefore represent a promising drug target for treating VCID and possibly Alzheimer's disease and other related dementias.SIGNIFICANCE STATEMENT The impact of reactive astrocytes in Alzheimer's disease and related dementias is poorly understood. Here, we evaluated Ca2+ responses and signaling in barrel cortex astrocytes of mice fed with a B-vitamin deficient diet that induces hyperhomocysteinemia (HHcy), cerebral vessel disease, and cognitive decline. Multiphoton imaging in awake mice with HHcy revealed augmented Ca2+ responses in individual astrocytes, but impaired signaling across astrocyte networks. Stimulation-evoked arteriole dilation and elevated red blood cell velocity in capillaries were also impaired in cortex of awake HHcy mice. Astrocyte-specific inhibition of the Ca2+-dependent transcription factor, NFAT, normalized cerebrovascular function in HHcy mice, improved synaptic properties in brain slices, and stabilized cognition. Results suggest that astrocytes are a mechanism and possible therapeutic target for vascular-related dementia.

Apolipoprotein E genotype-dependent nutrigenetic effects to prebiotic inulin for modulating systemic metabolism and neuroprotection in mice via gut-brain axis.

OBJECTIVE: The goal of the study was to identify the potential nutrigenetic effects to inulin, a prebiotic fiber, in mice with different human apolipoprotein E (APOE) genetic variants. Specifically, we compared responses to inulin for the potential modulation of the systemic metabolism and neuroprotection via gut-brain axis in mice with human APOE ϵ3 and ϵ4 alleles. METHOD: We performed experiments with young mice expressing the human APOE3 (E3FAD mice and APOE4 gene (E4FAD mice). We fed mice with either inulin or control diet for 16 weeks starting from 3 months of age. We determined gut microbiome diversity and composition using16s rRNA sequencing, systemic metabolism using in vivo MRI and metabolomics, and blood-brain barrier (BBB) tight junction expression using Western blot. RESULTS: In both E3FAD and E4FAD mice, inulin altered the alpha and beta diversity of the gut microbiome, increased beneficial taxa of bacteria and elevated cecal short chain fatty acid and hippocampal scyllo-inositol. E3FAD mice had altered metabolism related to tryptophan and tyrosine, while E4FAD mice had changes in the tricarboxylic acid cycle, pentose phosphate pathway, and bile acids. Differences were found in levels of brain metabolites related to oxidative stress, and levels of Claudin-1 and Claudin-5 BBB tight junction expression. DISCUSSION: We found that inulin had many similar beneficial effects in the gut and brain for both E3FAD and E4FAD mice, which may be protective for brain functions and reduce risk for neurodegeneration. . E3FAD and E4FAD mice also had distinct responses in several metabolic pathways, suggesting an APOE-dependent nutrigenetic effects in modulating systemic metabolism and neuroprotection.

Exercise-mediated alteration of hippocampal Dicer mRNA and miRNAs is associated with lower BACE1 gene expression and Aß1-42 in female 3xTg-AD mice.

Changes to cerebral miRNA expression have been implicated in the progression of Alzheimer's disease (AD), as miRNAs that regulate the expression of gene products involved in amyloid beta (Aß) processing, such as BACE1, are dysregulated in those that suffer from AD. Exercise training improves cognition and reduces BACE1 and Aß-plaque burden; however, the mechanisms are not fully understood. Using our progressive weighted wheel running (PoWeR) exercise program, we assessed the effect of 20 wk of exercise training on changes in hippocampal miRNA expression in female 3xTg-AD (3xTg) mice. PoWeR was sufficient to promote muscle hypertrophy and increase myonuclear abundance. Furthermore, PoWeR elevated hippocampal Dicer gene expression in 3xTg mice, while altering miRNA expression toward a more wild-type profile. Specifically, miR-29, which is validated to target BACE1, was significantly lower in sedentary 3xTg mice when compared with wild-type but was elevated following PoWeR. Accordingly, BACE1 gene expression, along with detergent-soluble Aß1-42, was lower in PoWeR-trained 3xTg mice. Our data suggest that PoWeR training upregulates Dicer gene expression to alter cerebral miRNA expression, which may contribute to reduced Aß accumulation and delay AD progression.NEW & NOTEWORTHY Previous studies have outlined the beneficial effects of exercise on lowering BACE1 expression and reducing Aß plaques. This study extends upon the work of others by outlining a new potential mechanism by which exercise elicits beneficial effects on Alzheimer's disease pathology, specifically through modulation of Dicer and miRNA expression. This is the first study to examine Dicer and miRNA expression in the hippocampus of the 3xTg model within the context of exercise.

APOE genotype-dependent pharmacogenetic responses to rapamycin for preventing Alzheimer's disease.

The ε4 allele of Apolipoprotein (APOE4) is the strongest genetic risk factor for Alzheimer's disease (AD), the most common form of dementia. Cognitively normal APOE4 carriers have developed amyloid beta (Aß) plaques and cerebrovascular, metabolic and structural deficits decades before showing the cognitive impairment. Interventions that can inhibit Aß retention and restore the brain functions to normal would be critical to prevent AD for the asymptomatic APOE4 carriers. A major goal of the study was to identify the potential usefulness of rapamycin (Rapa), a pharmacological intervention for extending longevity, for preventing AD in the mice that express human APOE4 gene and overexpress Aß (the E4FAD mice). Another goal of the study was to identify the potential pharmacogenetic differences in response to rapamycin between the E4FAD and E3FAD mice, the mice with human APOE ε3 allele. We used multi-modal MRI to measure in vivo cerebral blood flow (CBF), neurotransmitter levels, white matter integrity, water content, cerebrovascular reactivity (CVR) and somatosensory response; used behavioral assessments to determine cognitive function; used biochemistry assays to determine Aß retention and blood-brain barrier (BBB) functions; and used metabolomics to identify brain metabolic changes. We found that in the E4FAD mice, rapamycin normalized bodyweight, restored CBF (especially in female), BBB activity for Aß transport, neurotransmitter levels, neuronal integrity and free fatty acid level, and reduced Aß retention, which were not observe in the E3FAD-Rapa mice. In contrast, E3FAD-Rapa mice had lower CVR responses, lower anxiety and reduced glycolysis in the brain, which were not seen in the E4FAD-Rapa mice. Further, rapamycin appeared to normalize lipid-associated metabolism in the E4FAD mice, while slowed overall glucose-associated metabolism in the E3FAD mice. Finally, rapamycin enhanced overall water content, water diffusion in white matter, and spatial memory in both E3FAD and E4FAD mice, but did not impact the somatosensory responses under hindpaw stimulation. Our findings indicated that rapamycin was able to restore brain functions and reduce AD risk for young, asymptomatic E4FAD mice, and there were pharmacogenetic differences between the E3FAD and E4FAD mice. As the multi-modal MRI methods used in the study are readily to be used in humans and rapamycin is FDA-approved, our results may pave a way for future clinical testing of the pharmacogenetic responses in humans with different APOE alleles, and potentially using rapamycin to prevent AD for asymptomatic APOE4 carriers.

Preventable Deaths in Multiple Trauma Patients: The Importance of Auditing and Continuous Quality Improvement.

BACKGROUND: Management errors during pre-hospital care, triage process and resuscitation have been widely reported as the major source of preventable and potentially preventable deaths in multiple trauma patients. Common tools for defining whether it is a preventable, potentially preventable or non-preventable death include the Advanced Trauma Life Support (ATLS®) clinical guideline, the Injury Severity Score (ISS) and the Trauma and Injury Severity Score (TRISS). Therefore, these surrogated scores were utilized in reviewing the study's trauma services. METHODS: Trauma data were prospectively collected and retrospectively reviewed from January 1, 2018, to December 31, 2018. All cases of trauma death were discussed and audited by the Hospital Trauma Committee on a regular basis. Standardized form was used to document the patient's management flow and details in every case during the meeting, and the final verdict (whether death was preventable or not) was agreed and signed by every member of the team. The reasons for the death of the patients were further classified into severe injuries, inappropriate/delayed examination, inappropriate/delayed treatment, wrong decision, insufficient supervision/guidance or lack of appropriate guidance. RESULTS: A total of 1913 trauma patients were admitted during the study period, 82 of whom were identified as major trauma (either ISS > 15 or trauma team was activated). Among the 82 patients with major trauma, eight were trauma-related deaths, one of which was considered a preventable death and the other 7 were considered unpreventable. The decision from the hospital's performance improvement and patient safety program indicates that for every trauma patient, basic life support principles must be followed in the course of primary investigations for bedside trauma series X-ray (chest and pelvis) and FAST scan in the resuscitation room by a person who meets the criteria for trauma team activation recommended by ATLS®. CONCLUSION: Mechanisms to rectify errors in the management of multiple trauma patients are essential for improving the quality of trauma care. Regular auditing in the trauma service is one of the most important parts of performance improvement and patient safety program, and it should be well established by every major trauma center in Mainland China. It can enhance the trauma management processes, decision-making skills and practical skills, thereby continuously improving quality and reducing mortality of this group of patients.

Complex IV-deficient Surf1(-/-) mice initiate mitochondrial stress responses.

Mutations in SURF1 (surfeit locus protein 1) COX (cytochrome c oxidase) assembly protein are associated with Leigh's syndrome, a human mitochondrial disorder that manifests as severe mitochondrial phenotypes and early lethality. In contrast, mice lacking the SURF1 protein (Surf1-/-) are viable and were previously shown to have enhanced longevity and a greater than 50% reduction in COX activity. We measured mitochondrial function in heart and skeletal muscle, and despite the significant reduction in COX activity, we found little or no difference in ROS (reactive oxygen species) generation, membrane potential, ATP production or respiration in isolated mitochondria from Surf1-/- mice compared with wild-type. However, blood lactate levels were elevated and Surf1-/- mice had reduced running endurance, suggesting compromised mitochondrial energy metabolism in vivo. Decreased COX activity in Surf1-/- mice is associated with increased markers of mitochondrial biogenesis [PGC-1α (peroxisome-proliferator-activated receptor γ co-activator 1α) and VDAC (voltage-dependent anion channel)] in both heart and skeletal muscle. Although mitochondrial biogenesis is a common response in the two tissues, skeletal muscle has an up-regulation of the UPRMT (mitochondrial unfolded protein response) and heart exhibits induction of the Nrf2 (nuclear factor-erythroid 2-related factor 2) antioxidant response pathway. These data are the first to show induction of the UPRMT in a mammalian model of decreased COX activity. In addition, the results of the present study suggest that impaired mitochondrial function can lead to induction of mitochondrial stress pathways to confer protective effects on cellular homoeostasis.

Living well with diabetes in Alaska.

Many people with diabetes mellitus experience minimal or no complications. Our objective was to determine the proportion of Alaska Native people who experienced four major complications or mortality and to identify factors that may be associated with these outcomes. We used records in a diabetes registry and clinical and demographic variables in our analyses. We used logistic regression and Cox Proportional Hazards models to evaluate associations of these parameters with death and complications that occurred prior to 2013. The study included 591 Alaska Native people with non-type 1 diabetes mellitus, diagnosed between 1986 and 1992. Over 60% of people in this study remained free of four major diabetes-related complications for the remainder of life or throughout the approximately 20-year study period. Lower BMI, higher age at diagnosis of diabetes, and use of at least one diabetes medication were associated with death and a composite of four complications. A majority of Alaska Native people with DM had none of four major complications over a 20-year period. Lower BMI and use of diabetes medications were associated with higher hazard for some deleterious outcomes. This suggests that goals in care of elders should be carefully individualised. In addition, we discuss several programme factors that we believe contributed to favourable outcomes.

mTOR inhibition enhances synaptic and mitochondrial function in Alzheimer's disease in an APOE genotype-dependent manner.

Apolipoprotein ε4 (APOE4) carriers develop brain metabolic dysfunctions decades before the onset of Alzheimer's disease (AD). A goal of the study is to identify if rapamycin, an inhibitor for the mammalian target of rapamycin (mTOR) inhibitor, would enhance synaptic and mitochondrial function in asymptomatic mice with human APOE4 gene (E4FAD) before they showed metabolic deficits. A second goal is to determine whether there may be genetic-dependent responses to rapamycin when compared to mice with human APOE3 alleles (E3FAD), a neutral AD genetic risk factor. We fed asymptomatic E4FAD and E3FAD mice with control or rapamycin diets for 16 weeks from starting from 3 months of age. Neuronal mitochondrial oxidative metabolism and excitatory neurotransmission rates were measured using in vivo 1H-[13C] proton-observed carbon-edited magnetic resonance spectroscopy, and isolated mitochondrial bioenergetic measurements using Seahorse. We found that rapamycin enhanced neuronal mitochondrial function, glutamate-glutamine cycling, and TCA cycle rates in the asymptomatic E4FAD mice. In contrast, rapamycin enhances glycolysis, non-neuronal activities, and inhibitory neurotransmission of the E3FAD mice. These findings indicate that rapamycin might be able to mitigate the risk for AD by enhancing brain metabolic functions for cognitively intact APOE4 carriers, and the responses to rapamycin are varied by APOE genotypes. Consideration of precision medicine may be needed for future rapamycin therapeutics.

Evidence-based screening, clinical care and health education recommendations for Alaska Native peoples with prediabetes living in southcentral Alaska: findings from the Alaska EARTH follow-up study.

Pre-diabetes (pre-DM) is a strong predictor of diabetes (DM) over time. This study investigated how much of the recent increase in pre-DM identified among Alaska Native (AN) peoples living in urban southcentral Alaska may be due to changes in diagnostic methods. We used clinical and demographic data collected at baseline between 2004 and 2006 and at follow-up collected between 2015 and 2017 from the urban southcentral Alaska Education and Research Towards Health (EARTH) cohort. We used descriptive statistics and logistic regression to explore differences in demographic and clinical variables among the identified pre-DM groups. Of 388 participants in the follow-up study, 243 had A1c levels indicating pre-DM with only 20 demonstrating pre-DM also by fasting blood glucose (FBG). Current smoking was the sole predictor for pre-DM by A1c alone while abdominal obesity and elevated FBG-predicted pre-DM by A1c+FBG. No participants had an elevated FBG without an A1c elevation. A substantial portion of the rise in pre-DM found among urban southcentral AN peoples in the EARTH follow-up study was due to the addition of A1c testing. Pre-DM by A1c alone should be used to motivate behavioural changes that address modifiable risk factors, including smoking cessation, physical activity and weight management.

Nonlinear coupling between cerebral blood flow, oxygen consumption, and ATP production in human visual cortex.

The purpose of this study was to investigate activation-induced hypermetabolism and hyperemia by using a multifrequency (4, 8, and 16 Hz) reversing-checkerboard visual stimulation paradigm. Specifically, we sought to (i) quantify the relative contributions of the oxidative and nonoxidative metabolic pathways in meeting the increased energy demands [i.e., ATP production (J(ATP))] of task-induced neuronal activation and (ii) determine whether task-induced cerebral blood flow (CBF) augmentation was driven by oxidative or nonoxidative metabolic pathways. Focal increases in CBF, cerebral metabolic rate of oxygen (CMRO(2); i.e., index of aerobic metabolism), and lactate production (J(Lac); i.e., index of anaerobic metabolism) were measured by using physiologically quantitative MRI and spectroscopy methods. Task-induced increases in J(ATP) were small (12.2-16.7%) at all stimulation frequencies and were generated by aerobic metabolism (approximately 98%), with %DeltaJ(ATP) being linearly correlated with the percentage change in CMRO(2) (r = 1.00, P < 0.001). In contrast, task-induced increases in CBF were large (51.7-65.1%) and negatively correlated with the percentage change in CMRO(2) (r = -0.64, P = 0.024), but positively correlated with %DeltaJ(Lac) (r = 0.91, P < 0.001). These results indicate that (i) the energy demand of task-induced brain activation is small (approximately 15%) relative to the hyperemic response (approximately 60%), (ii) this energy demand is met through oxidative metabolism, and (iii) the CBF response is mediated by factors other than oxygen demand.

Self-Supervised Learning Application on COVID-19 Chest X-ray Image Classification Using Masked AutoEncoder.

The COVID-19 pandemic has underscored the urgent need for rapid and accurate diagnosis facilitated by artificial intelligence (AI), particularly in computer-aided diagnosis using medical imaging. However, this context presents two notable challenges: high diagnostic accuracy demand and limited availability of medical data for training AI models. To address these issues, we proposed the implementation of a Masked AutoEncoder (MAE), an innovative self-supervised learning approach, for classifying 2D Chest X-ray images. Our approach involved performing imaging reconstruction using a Vision Transformer (ViT) model as the feature encoder, paired with a custom-defined decoder. Additionally, we fine-tuned the pretrained ViT encoder using a labeled medical dataset, serving as the backbone. To evaluate our approach, we conducted a comparative analysis of three distinct training methods: training from scratch, transfer learning, and MAE-based training, all employing COVID-19 chest X-ray images. The results demonstrate that MAE-based training produces superior performance, achieving an accuracy of 0.985 and an AUC of 0.9957. We explored the mask ratio influence on MAE and found ratio = 0.4 shows the best performance. Furthermore, we illustrate that MAE exhibits remarkable efficiency when applied to labeled data, delivering comparable performance to utilizing only 30% of the original training dataset. Overall, our findings highlight the significant performance enhancement achieved by using MAE, particularly when working with limited datasets. This approach holds profound implications for future disease diagnosis, especially in scenarios where imaging information is scarce.

Formyl peptide receptor 1 is involved in surgery-induced neuroinflammation and dysfunction of learning and memory in mice.

Postoperative cognitive dysfunction (POCD) is a common complication after surgery. Peripheral immune cells may contribute to the development of POCD. However, molecules that are important for this contribution are not known. We hypothesize that formyl peptide receptor 1 (FPR1), a molecule critical for the migration of the monocytes and neutrophils into the brain after brain ischemia, is central to the development of postoperative neuroinflammation and dysfunction of learning and memory. Male C57BL/6 (wild-type) mice and FPR1-/- mice received right carotid artery exposure surgery. Some wild-type mice received cFLFLF, an FPR1 antagonist. Mouse brains were harvested 24 h after the surgery for biochemical analysis. Mice were subjected to the Barnes maze and fear conditioning tests to determine their learning and memory from 2 weeks after the surgery. We found that surgery increased FPR1 in the brain and proinflammatory cytokines in the blood and brain of wild-type mice. Surgery also impaired their learning and memory. cFLFLF attenuated these effects. Surgery did not induce an increase in the proinflammatory cytokines and impairment of learning and memory in FPR1-/- mice. These results suggest that FPR1 is important for the development of neuroinflammation and dysfunction of learning and memory after surgery. Specific interventions that inhibit FPR1 may be developed to reduce POCD.

Efficient Training on Alzheimer's Disease Diagnosis with Learnable Weighted Pooling for 3D PET Brain Image Classification.

Three-dimensional convolutional neural networks (3D CNNs) have been widely applied to analyze Alzheimer's disease (AD) brain images for a better understanding of the disease progress or predicting the conversion from cognitively impaired (CU) or mild cognitive impairment status. It is well-known that training 3D-CNN is computationally expensive and with the potential of overfitting due to the small sample size available in the medical imaging field. Here we proposed a novel 3D-2D approach by converting a 3D brain image to a 2D fused image using a Learnable Weighted Pooling (LWP) method to improve efficient training and maintain comparable model performance. By the 3D-to-2D conversion, the proposed model can easily forward the fused 2D image through a pre-trained 2D model while achieving better performance over different 3D and 2D baselines. In the implementation, we chose to use ResNet34 for feature extraction as it outperformed other 2D CNN backbones. We further showed that the weights of the slices are location-dependent and the model performance relies on the 3D-to-2D fusion view, with the best outcomes from the coronal view. With the new approach, we were able to reduce 75% of the training time and increase the accuracy to 0.88, compared with conventional 3D CNNs, for classifying amyloid-beta PET imaging from the AD patients from the CU participants using the publicly available Alzheimer's Disease Neuroimaging Initiative dataset. The novel 3D-2D model may have profound implications for timely AD diagnosis in clinical settings in the future.

Prebiotic inulin enhances gut microbial metabolism and anti-inflammation in apolipoprotein E4 mice with sex-specific implications.

Gut dysbiosis has been identified as a crucial factor of Alzheimer's disease (AD) development for apolipoprotein E4 (APOE4) carriers. Inulin has shown the potential to mitigate dysbiosis. However, it remains unclear whether the dietary response varies depending on sex. In the study, we fed 4-month-old APOE4 mice with inulin for 16 weeks and performed shotgun metagenomic sequencing to determine changes in microbiome diversity, taxonomy, and functional gene pathways. We also formed the same experiments with APOE3 mice to identify whether there are APOE-genotype dependent responses to inulin. We found that APOE4 female mice fed with inulin had restored alpha diversity, significantly reduced Escherichia coli and inflammation-associated pathway responses. However, compared with APOE4 male mice, they had less metabolic responses, including the levels of short-chain fatty acids-producing bacteria and the associated kinases, especially those related to acetate and Erysipelotrichaceae. These diet- and sex- effects were less pronounced in the APOE3 mice, indicating that different APOE variants also play a significant role. The findings provide insights into the higher susceptibility of APOE4 females to AD, potentially due to inefficient energy production, and imply the importance of considering precision nutrition for mitigating dysbiosis and AD risk in the future.

Gut microbiome association with brain imaging markers, APOE genotype, calcium and vegetable intakes, and obesity in healthy aging adults.

Introduction: Advanced age is a significant factor in changes to brain physiology and cognitive functions. Recent research has highlighted the critical role of the gut microbiome in modulating brain functions during aging, which can be influenced by various factors such as apolipoprotein E (APOE) genetic variance, body mass index (BMI), diabetes, and dietary intake. However, the associations between the gut microbiome and these factors, as well as brain structural, vascular, and metabolic imaging markers, have not been well explored. Methods: We recruited 30 community dwelling older adults between age 55-85 in Kentucky. We collected the medical history from the electronic health record as well as the Dietary Screener Questionnaire. We performed APOE genotyping with an oral swab, gut microbiome analysis using metagenomics sequencing, and brain structural, vascular, and metabolic imaging using MRI. Results: Individuals with APOE e2 and APOE e4 genotypes had distinct microbiota composition, and higher level of pro-inflammatory microbiota were associated higher BMI and diabetes. In contrast, calcium- and vegetable-rich diets were associated with microbiota that produced short chain fatty acids leading to an anti-inflammatory state. We also found that important gut microbial butyrate producers were correlated with the volume of the thalamus and corpus callosum, which are regions of the brain responsible for relaying and processing information. Additionally, putative proinflammatory species were negatively correlated with GABA production, an inhibitory neurotransmitter. Furthermore, we observed that the relative abundance of bacteria from the family Eggerthellaceae, equol producers, was correlated with white matter integrity in tracts connecting the brain regions related to language, memory, and learning. Discussion: These findings highlight the importance of gut microbiome association with brain health in aging population and could have important implications aimed at optimizing healthy brain aging through precision prebiotic, probiotic or dietary interventions.

Blood longitudinal (T1) and transverse (T2) relaxation time constants at 11.7 Tesla.

OBJECT: The goal of the study was to determine blood T(1) and T(2) values as functions of oxygen saturation (Y), temperature (Temp) and hematocrit (Hct) at an ultrahigh MR field (11.7 T) and explore their impacts on physiological measurements, including cerebral blood flow (CBF), blood volume (CBV) and oxygenation determination. MATERIALS AND METHODS: T(1) and T(2) were simultaneously measured. Temperature was adjusted from 25 to 40°C to determine Temp dependence; Hct of 0.17-0.51 to evaluate Hct dependence at 25 and 37°C; and Y of 40-100% to evaluate Y dependence at 25 and 37°C. Comparisons were made with published data obtained at different magnetic field strengths (B(0)). RESULTS: T(1) was positively correlated with Temp, independent of Y, and negatively correlated with Hct. T(2) was negatively correlated with Temp and Hct, but positively correlated with Y, in a non-linear fashion. T(1) increased linearly with B(0), whereas T(2) decreased exponentially with B(0). CONCLUSION: This study reported blood T(1) and T(2) measurements at 11.7 T for the first time. These blood relaxation data could have implications in numerous functional and physiological MRI studies at 11.7 T.

Impact of local anesthesia block on pain medication use and length of hospital stay in elderly indigenous patients in Alaska hospitalized for fragility fracture.

Introduction: Fragility fractures (low-energy, minimal-trauma fractures) are common in the aging population and can lead to decreased function, increased mortality, and long-lasting pain. Although opioids are helpful in reducing acute postoperative pain, they present risks that may lead to increased morbidity and mortality. Materials and Methods: This was a retrospective review of medical records of all Alaska Native and American Indian people older than 50 years, who received surgery for hip fracture repair between January 2018 and June 2019 (n = 128). Results: We found that receipt of a peripheral nerve block (PNB) is a predictor for decreased length of hospital stay. However, receipt of PNB did not predict a reduction in postoperative morphine milligram equivalents opioid doses. Discussion: Further study is required to determine whether one PNB method is superior to others based on individual-level characteristics.

Gut microbial dysbiosis correlates with stroke severity markers in aged rats.

Background: An imbalanced gut microbial community, or dysbiosis, has been shown to occur following stroke. It is possible that this dysbiosis negatively impacts stroke recovery and rehabilitation. Species level resolution measurements of the gut microbiome following stroke are needed to develop and test precision interventions such as probiotic or fecal microbiota transplant therapies that target the gut microbiome. Previous studies have used 16S rRNA amplicon sequencing in young male mice to obtain broad profiling of the gut microbiome at the genus level following stroke, but further investigations will be needed with whole genome shotgun sequencing in aged rats of both sexes to obtain species level resolution in a model which will better translate to the demographics of human stroke patients. Methods: Thirty-nine aged male and female rats underwent middle cerebral artery occlusion. Fecal samples were collected before stroke and 3 days post stroke to measure gut microbiome. Machine learning was used to identify the top ranked bacteria which were changed following stroke. MRI imaging was used to obtain infarct and edema size and cerebral blood flow (CBF). ELISA was used to obtain inflammatory markers. Results: Dysbiosis was demonstrated by an increase in pathogenic bacteria such as Butyricimonas virosa (15.52 fold change, p < 0.0001), Bacteroides vulgatus (7.36 fold change, p < 0.0001), and Escherichia coli (47.67 fold change, p < 0.0001). These bacteria were positively associated with infarct and edema size and with the inflammatory markers Ccl19, Ccl24, IL17a, IL3, and complement C5; they were negatively correlated with CBF. Conversely, beneficial bacteria such as Ruminococcus flavefaciens (0.14 fold change, p < 0.0001), Akkermansia muciniphila (0.78 fold change, p < 0.0001), and Lactobacillus murinus (0.40 fold change, p < 0.0001) were decreased following stroke and associated with all the previous parameters in the opposite direction of the pathogenic species. There were not significant microbiome differences between the sexes. Conclusion: The species level resolution measurements found here can be used as a foundation to develop and test precision interventions targeting the gut microbiome following stroke. Probiotics that include Ruminococcus flavefaciens, Akkermansia muciniphila, and Lactobacillus murinus should be developed to target the deficit following stroke to measure the impact on stroke severity.

Inulin Supplementation Mitigates Gut Dysbiosis and Brain Impairment Induced by Mild Traumatic Brain Injury during Chronic Phase.

Mild traumatic brain injury (mTBI) has been shown to acutely alter the gut microbiome diversity and composition, known as dysbiosis, which can further exacerbate metabolic and vascular changes in the brain in both humans and rodents. However, it remains unknown how mTBI affects the gut microbiome in the chronic phase recovery (past one week post injury). It is also unknown if injury recovery can be improved by mitigating dysbiosis. The goal of the study is to fill the knowledge gap. First, we aim to understand how mTBI alters the gut microbiome through the chronic period of recovery (3 months post injury). In addition, as the gut microbiome can be modulated by diet, we also investigated if prebiotic inulin, a fermentable fiber that promotes growth of beneficial bacteria and metabolites, would mitigate dysbiosis, improve systemic metabolism, and protect brain structural and vascular integrity when administered after 3 months post closed head injury (CHI). We found that CHI given to male mice at 4 months of age induced gut dysbiosis which peaked at 1.5 months post injury, reduced cerebral blood flow (CBF) and altered brain white matter integrity. Interestingly, we also found that Sham mice had transient dysbiosis, which peaked 24 hours after injury and then normalized. After 8 weeks of inulin feeding, CHI mice had increased abundance of beneficial/anti-inflammatory bacteria, reduced abundance of pathogenic bacteria, enriched levels of short-chain fatty acids, and restored CBF in both hippocampi and left thalamus, compared to the CHI-control fed and Sham groups. Using machine learning, we further identified top bacterial species that separate Sham and CHI mice with and without the diet. Our results indicate that there is an injury- and time-dependent dysbiosis between CHI and Sham mice; inulin is effective to mitigate dysbiosis and improve brain injury recovery in the CHI mice. As there are currently no effective treatments for mTBI, the study may have profound implications for developing therapeutics or preventive interventions in the future.

Extended Middle Cerebral Artery Occlusion (MCAO) Model to Mirror Stroke Patients Undergoing Thrombectomy.

Stroke remains a leading global cause of death and disability. In the last decade, the therapeutic window for mechanical thrombectomy has increased from a maximum of 6 to 24 h and beyond. While endovascular advancements have improved rates of recanalization, no post-stroke pharmacotherapeutics have been effective in enhancing neurorepair and recovery. New experimental models are needed to closer mimic the human patient. Our group has developed a model of transient 5-h occlusion in rats to mimic stroke patients undergoing thrombectomy. Our procedure was designed specifically in aged rats and was optimized based on sex in order to keep mortality and extent of injury consistent between aged male and female rats. This model uses a neurological assessment modeled after the NIH Stroke Scale. Finally, the potential for translation between our rat model of stroke and humans was assessed using comparative gene expression for key inflammatory genes. This model will be useful in the evaluation of therapeutic targets to develop adjuvant treatments for large vessel occlusion during the thrombectomy procedure.