Age-Related Brain Atrophy and the Positive Effects of Behavioral Enrichment in Middle-Aged Beagles.

Aging dogs serve as a valuable preclinical model for Alzheimer's disease (AD) due to their natural age-related development of ß-amyloid (Aß) plaques, human-like metabolism, and large brains that are ideal for studying structural brain aging trajectories from serial neuroimaging. Here we examined the effects of chronic treatment with the calcineurin inhibitor (CNI) tacrolimus or the nuclear factor of activated T cells (NFAT)-inhibiting compound Q134R on age-related canine brain atrophy from a longitudinal study in middle-aged beagles (36 females, 7 males) undergoing behavioral enrichment. Annual MRI was analyzed using modern, automated techniques for region-of-interest-based and voxel-based volumetric assessments. We found that the frontal lobe showed accelerated atrophy with age, while the caudate nucleus remained relatively stable. Remarkably, the hippocampus increased in volume in all dogs. None of these changes were influenced by tacrolimus or Q134R treatment. Our results suggest that behavioral enrichment can prevent atrophy and increase the volume of the hippocampus but does not prevent aging-associated prefrontal cortex atrophy.

Vaping and smoking cue reactivity in young adult electronic cigarette users who have never smoked combustible cigarettes: A functional neuroimaging study.

Introduction: The rapid growth in the use of electronic cigarettes (e-cigarettes) among young adults who have never smoked combustible cigarettes is concerning, as it raises the potential for chronic vaping and nicotine addiction. A key characteristic of drug addiction is the elevated neural response to conditioned drug-related cues (i.e., cue reactivity). Generalized reactivity to both vaping and smoking cues may signify an increased risk for smoking initiation in non- smoking vapers. In this study, we used functional magnetic resonance imaging (fMRI) to evaluate brain responses to vaping and smoking cues in young adult never-smoking vapers. Methods: Sixty-six young adult never-smoking vapers underwent functional MRI while viewing visual cues pertaining to vaping, smoking, and nicotine-unrelated unconditioned reward (i.e., food). A priori region-of-interest analysis combined with exploratory whole-brain analysis was performed to characterize neural reactivity to vaping and smoking cues in comparison to food cues. Results: The medial prefrontal cortex and the posterior cingulate cortex, regions that play a key role in drug cue reactivity, showed significantly increased neural response to vaping cues compared to food cues. The posterior cingulate cortex additionally showed increased neural responses to smoking cues compared to food cues. Conclusions: Despite never having smoked combustible cigarettes, young adult vapers exhibited heightened neural susceptibility to both vaping and smoking cues within brain systems associated with cue reactivity. The findings shed light on the mechanisms underlying nicotine addiction and smoking initiation risk in this critical population and may contribute to the development of science-based interventions and regulatory measures in the future. IMPLICATIONS: The escalating vaping prevalence among US never-smoking young adults is alarming, due to its potential ramifications for nicotine addiction development. Nicotine addiction is characterized by elevated neural response to conditioned nicotine-related cues. Using functional neuroimaging, we showed that young adult non-smoking vapers exhibited heightened neural susceptibility to both vaping and smoking cues within brain systems previously associated with cue reactivity. Such cross-reactivity to both types of nicotine cues may serve as the mechanism underlying nicotine addiction and smoking initiation risk in this population. Our findings may contribute to the development of science-based interventions and regulatory measures addressing the vaping epidemic.

Everything but the Kitchen Sink: An Analysis of Bacterial and Chemical Contaminants Found in Syringe Residue From People Who Inject Drugs.

Background: People who inject drugs (PWID) are at high risk of severe wounds, invasive infections, and overdoses. To date, there are few data on the bacterial and chemical contaminants PWID are exposed to when using illicitly manufactured fentanyls and stimulants. Methods: Previously used injection drug use equipment was recovered in St Louis, Missouri, by harm reduction organizations over a 12-month period. Syringe residue was analyzed for bacterial contaminants by routine culturing followed by whole genome sequencing of single bacterial isolates. Chemical adulterants in syringe residue were identified by liquid chromatography-mass spectrometry. Results: Bacteria were cultured from 58.75% of 160 syringes analyzed. Polymicrobial growth was common and was observed in 23.75% of samples. Bacillus cereus was the most common pathogen present and was observed in 20.6% of syringe residues, followed closely by Staphylococcus aureus at 18.8%. One hundred syringes underwent mass spectrometry, which demonstrated that chemical adulterants were common and included caffeine, diphenhydramine, lidocaine, quinine, and xylazine. Conclusions: Analysis of syringe residue from discarded drug use equipment demonstrates both chemical and biological contaminants, including medically important pathogens and adulterants.

Polypathologies and Animal Models of Traumatic Brain Injury.

Traumatic brain injury (TBI) is an important health issue for the worldwide population, as it causes long-term pathological consequences for a diverse group of individuals. We are yet to fully elucidate the significance of TBI polypathologies, such as neuroinflammation and tau hyperphosphorylation, and their contribution to the development of chronic traumatic encephalopathy (CTE) and other neurological conditions. To advance our understanding of TBI, it is necessary to replicate TBI in preclinical models. Commonly used animal models include the weight drop model; these methods model human TBI in various ways and in different animal species. However, animal models have not demonstrated their clinical utility for identifying therapeutic interventions. Many interventions that were successful in improving outcomes for animal models did not translate into clinical benefit for patients. It is important to review current animal models and discuss their strengths and limitations within a TBI context. Modelling human TBI in animals encounters numerous challenges, yet despite these barriers, the TBI research community is working to overcome these difficulties. Developments include advances in biomarkers, standardising, and refining existing models. This progress will improve our ability to model TBI in animals and, therefore, enhance our understanding of TBI and, potentially, how to treat it.

Impact of Didactic Instruction on the Utilization of Point-of-Care Ultrasound in Family Medicine Residents.

Background and Objectives In 2014, the Council of Academic Family Medicine released recommendations for the education of family medicine residents in point-of-care ultrasound (POCUS) curricula for Family Medicine Residency programs. One barrier to resident education in POCUS is the lack of access to equipment. This pilot study evaluates whether introducing didactic education on POCUS within a Family Medicine Residency program, with limited access to equipment, correlated with increased utilization of ultrasound by residents. Methods Sixteen family medicine residents participated in the intervention, consisting of a four-hour didactic ultrasound session. Resident confidence in POCUS was evaluated utilizing a Likert scale. Resident utilization of POCUS in a clinical setting was also evaluated by review and analysis of resident procedure logs in the New Innovations database. Results The resident confidence in all skills increased immediately after the completion of the didactic teaching session. Residents demonstrated improved confidence in needle guidance immediately and six weeks after the session (p < 0.001). A review of resident activity two years after the intervention revealed a 9.6% increase in the proportion of resident ultrasounds performed compared to the academic year before the intervention. Conclusions Access to equipment is an ongoing barrier to Family Medicine Residency programs in providing education on POCUS. The results of this study indicate that introducing the basics of POCUS via a didactic teaching session not only increased resident confidence in basic ultrasound but also correlated with increased utilization of POCUS. This increased utilization occurred despite residents not having access to ultrasound in their home clinics.

Educational Intervention Among Adolescents and Young Adults on Emergency Contraception Options.

PURPOSE: Emergency contraception (EC), the 'last chance' contraceptive method, has gained significance post-Roe, but most young people do not know their options. METHODS: We conducted an educational intervention on EC among 1,053 students aged 18-25 years. We assessed changes in knowledge of key aspects of EC using generalized estimating equations. RESULTS: At baseline, virtually no one was aware of the intrauterine device for EC (4%), but postintervention, 89% correctly identified intrauterine devices as the most effective EC (adjusted odds ratio [aOR] = 116.6; 95% confidence interval [CI] 62.4, 217.8). Knowledge that levonorgestrel pills could be accessed without a prescription grew (60%-90%; aOR = 9.7, 95% CI 6.7-14.0), as did knowledge that pills work best when taken as soon as possible (75%-95%; aOR = 9.6, 95% CI 6.1-14.9). Multivariate results showed adolescent and young adult participants absorbed these key concepts across age, gender, and sexual orientation. DISCUSSION: Timely interventions are needed to empower youth with knowledge of EC options.

Improved parent self-efficacy following pediatric evaluation: Evidence for value of a telemedicine approach in psychological and neuropsychological assessment.

Objective: While considerable inquiry is currently underway into the comparability of psychological test results obtained in onsite/in-person settings versus telemedicine settings, there has been less attention given to the comparability of the impact/outcome of the assessment process across settings. The current quality improvement study conceptualized impact/outcome according to the model of Austin et al. and sought to determine whether the prior finding of increased parent self-efficacy following onsite neuropsychological assessment was also observed when psychological and neuropsychological assessment was conducted via a telemedicine modality. Method: In the course of standard care delivery, ratings from Austin et al.'s four parent self-efficacy items were obtained at time 1 prior to patients' assessment visits and then again at time 2 either (1) following their last assessment/feedback visit (the Complete Assessment group; n = 157) or (2) in the middle of the assessment process prior to the last planned visit (the Incomplete Assessment group; n = 117). Results: Analyses revealed significant findings for time and time × group. Parent self-efficacy ratings improved over time in both groups, with significantly higher ratings in the Complete Assessment group at time 2. When compared to reference means from the in-person/onsite Austin et al. study, ratings from the current study found comparable improvement in parent self-efficacy achieved via telemedicine assessment in the Complete Assessment group. Conclusions: These data support the use of telemedicine based psychological and neuropsychological evaluation and provide preliminary evidence that the impact/outcome is comparable with in-person/onsite assessment.

Spirited away: Can ethanol testing in add-on orders provide meaningful results?

Ethanol is a volatile substance, and specimens need to be tightly capped prior to analysis to prevent evaporative loss. However, add-on requests in previously decapped tubes are commonly received, yet ethanol stability in this setting is unclear. We compared the stability of ethanol in capped vs decapped tubes in the context of routine laboratory automation, storage time, and specimen volumes. Serum specimens were pooled and spiked with ethanol followed by simulating an add-on scenario. Additionally, to evaluate ethanol stability at room temperature for extended times, ethanol concentrations were measured in capped or decapped tubes containing 0.5 mL or 0.1 mL samples over a 4 h time course. Finally, the risk of misclassification of ethanol results in decapped tubes was evaluated near the critical value threshold (∼54 mmol/L). The add-on tubes had a mean recovery of 101.5 % (95 % CI: 97.7-105.4 %) relative to the direct tubes. The time-course experiment showed an average recovery of 87.4 % (95 % CI: 81.8-94.0 %) at the 4 h time point in decapped 0.5 mL specimens. An average recovery of 85.4 % (95 % CI: 84.2-86.1 %) was observed for specimens spiked near the critical value threshold. Importantly, all measurements with 0.5 mL specimen volume were within 25 %, which is the total allowable error (TAE) of the assay.However, with a 0.1 mL volume, specimens cross the TAE threshold just after 1 h, and the percent recovery at 4 h dropped to 52.9 % (95 % CI: 50.2-55.7 %). In conclusion, ethanol testing in decapped tubes remains within the TAE for up to 4 h in specimens with a 0.5 mL volume. Therefore, add-on ethanol testing using routine laboratory automation and storage conditions can be successfully performed.

Protocols for the social transfer of pain and analgesia in mice.

We provide protocols for the social transfer of pain and analgesia in mice. We describe the steps to induce pain or analgesia (pain relief) in bystander mice with a 1-h social interaction with a partner injected with CFA (complete Freund's adjuvant) or CFA and morphine, respectively. We detail behavioral tests to assess pain or analgesia in the untreated bystander mice. This protocol has been validated in mice and rats and can be used for investigating mechanisms of empathy. For complete details on the use and execution of this protocol, please refer to Smith et al. (2021).

Bacterioplankton dispersal and biogeochemical function across Alaskan Arctic catchments.

In Arctic catchments, bacterioplankton are dispersed through soils and streams, both of which freeze and thaw/flow in phase, seasonally. To characterize this dispersal and its potential impact on biogeochemistry, we collected bacterioplankton and measured stream physicochemistry during snowmelt and after vegetation senescence across multiple stream orders in alpine, tundra, and tundra-dominated-by-lakes catchments. In all catchments, differences in community composition were associated with seasonal thaw, then attachment status (i.e. free floating or sediment associated), and then stream order. Bacterioplankton taxonomic diversity and richness were elevated in sediment-associated fractions and in higher-order reaches during snowmelt. Families Chthonomonadaceae, Pyrinomonadaceae, and Xiphinematobacteraceae were abundantly different across seasons, while Flavobacteriaceae and Microscillaceae were abundantly different between free-floating and sediment-associated fractions. Physicochemical data suggested there was high iron (Fe+ ) production (alpine catchment); Fe+ production and chloride (Cl- ) removal (tundra catchment); and phosphorus (SRP) removal and ammonium (NH4 + ) production (lake catchment). In tundra landscapes, these 'hot spots' of Fe+ production and Cl- removal accompanied shifts in species richness, while SRP promoted the antecedent community. Our findings suggest that freshet increases bacterial dispersal from headwater catchments to receiving catchments, where bacterioplankton-mineral relations stabilized communities in free-flowing reaches, but bacterioplankton-nutrient relations stabilized those punctuated by lakes.

Parent Satisfaction With Outpatient Telemedicine Services During the COVID-19 Pandemic: A Repeated Cross-Sectional Study.

Prior to the COVID-19 pandemic, the development of hospital-based telemedicine services had been slow and circumscribed in scope due to insurance and licensure restrictions. As these restrictions were eased during the COVID-19 pandemic to facilitate ongoing patient care, the public health emergency facilitated a rapid expansion and utilization of telemedicine services across the ambulatory service sector. Objectives: The current quality improvement (QI) study utilized this unprecedented opportunity to evaluate the use of telemedicine services across a variety of clinical disciplines and patient groups. Methods: Caregivers of patients (ages 0-21) who received care through an outpatient specialty center provided experience ratings of telemedicine services delivered during the initial pandemic months (March-June 2020; N = 1311) or during the national "winter surge" in late 2020 (November 2020-February 2021; N = 1395). Questionnaires were distributed electronically following the clinical visits, and ANCOVA was employed (with patient age as the covariate) to determine if caregiver responses differed based on patient demographic characteristics. Results: Ratings of patient satisfaction with services were very strong at both time points; greater variability in scores was noted when caregivers were asked if they would use telemedicine services again. At both time points, younger patient age (i.e., age 0-5) was associated with decreased caregiver willingness to use telemedicine services in the future. Smaller effects were seen for certain "hands on" therapies (occupational, physical, and speech) during the initial months of the pandemic and for proximity to the hospital during the "winter surge." Conclusions: These data suggest a very positive overall caregiver response to telemedicine-based services during the COVID-19 pandemic. Several areas of potential improvement/innovation were identified, including the delivery of telemedicine therapies (e.g., occupational, physical, and speech) services to young patients (i.e., aged 0-5).

Care home practitioners' perceptions of the barriers and facilitators for using off-the-shelf gaming technology with people with dementia.

Background: Off-the-shelf digital gaming technology has been shown to support the well-being of people with dementia. Yet, to date, it is rarely adopted within dementia care practice, particularly within care homes. Drawing on a descriptive, qualitative approach, this is the first study that has sought to explore care home practitioners' perceptions of the barriers and facilitators for using gaming technology within their workplace. Method: Data were collected across eight focus groups in the south of England with a total of 39 care home workers. These were analysed inductively following the 6-stage thematic process as outlined by Braun and Clarke (2006). Findings: Three themes, constructed from the data suggested, the care environment, staff knowledge and skills for inclusive gaming, and staff perceptions about capabilities (their own and those of people with dementia) inhibited or facilitated the use of gaming technology in care homes. The findings were interpreted through a combination of the Capability, Opportunity, Motivation and Behaviour model and the Theoretical Domains Framework to provide theory-based insights into the mechanisms for supporting behaviour change and implementation within the care home context. Conclusions: We argue for the need to target wider institutional barriers alongside providing inclusive training for care staff on incorporating gaming technology within their person-centred care approaches. Through these mechanisms, they can be provided with the capabilities, opportunities and motivation to integrate gaming technology within their practice, and thus facilitate the process of culture change within care homes.

Associations between anxiety, centromedial amygdala volume, and complex verbal fluency in middle-aged to older adults.

Symptoms of anxiety are related to decreases in cognitive performance in middle-aged to older adults (i.e., ages 50 and older; MOA). Verbal fluency (VF), assessed with the Delis-Kaplan Executive Function System (D-KEFS) Category Switching (VF-CS) task, captures elements of executive function such as semantic memory, response initiation and inhibition, and cognitive flexibility. The present study examined the link between anxiety symptoms and VF-CS to better understand how this association affects such executive functions in MOA. We hypothesized that higher subclinical Beck Anxiety Inventory (BAI) scores would be associated with lower VF-CS. To further investigate the underlying neurobiological basis of an expected inverse relationship, total amygdala volume, centromedial amygdala (CMA) volume, and basolateral amygdala (BLA) volume were examined as they related to VF-CS scores on the D-KEFS. Based on extant research on connectivity and functioning between the CMA and BLA, we hypothesized that larger BLA volumes would be associated with lower anxiety scores and exhibit positive relationships with VF-CS. A sample of 63 MOA were recruited from the Providence, Rhode Island area as a part of a parent study on cardiovascular diseases. Participants completed self-report measures about physical and emotional health, a neuropsychological assessment, and a magnetic resonance imaging scan (MRI). Multiple hierarchical regressions were performed to examine relationships between variables of interest. Contrary to hypotheses, no significant relationship emerged between VF-CS and BAI scores, and BLA volume was not associated with either BAI scores or VF-CS. However, a significant positive relationship was observed between CMA volume and VF-CS. The significant relationship found between CMA and VF-CS may reflect the upward slope of the quadratic relationship between arousal and cognitive performance on the Yerkes-Dodson curve. These findings newly implicate CMA volume specifically as a possible neuromarker linking emotional arousal and cognitive performance in MOA.

How much testing can a kid take? Feasibility of collecting pediatric patient experience ratings of neuropsychological and psychological assessment.

Parent-reported satisfaction is an important outcome measure in pediatric neuropsychology; however, self-report of patient experience following lengthy pediatric assessments has been under-investigated. Written at a first grade reading level and utilizing touch screen and read-aloud functionality, a set of 15 operationally-focused items were administered to evaluate pediatric patient experience of neuropsychological and psychological assessment. One-hundred ninety-seven clinically-referred patients (M age = 11.74, SD = 3.17, range = 5.86-19.02 years, 56% male) answered the post-assessment survey. The majority of patients (n = 167; 84.77%) accurately completed the initial two validity items, even though many had parent-reported ratings of reading difficulty. More than a third of patients indicated that the assessment made them tired (39%), but fewer patients reported feeling bored (13%) or worried (7%) during testing. Moreover, most patients reported having fun (66%) and many indicated that testing was preferable to other activities typically performed at that same time (i.e., school, homework). Responses to items assessing the child's interactions with the clinician and the child's effort provided little variation and were answered in a socially desirable manner. Items that focused upon the child's personal response to the assessment appointment (e.g., boredom, worry), however, elicited greater variance in patient responding. In general, patient responses did not suggest that assessment was an aversive experience. Overall, these proof of concept findings suggest that most referred pediatric patients, even those with learning issues, may be capable of independently navigating and completing self-report questionnaires while providing differential responses to items assessing clinical experience. Self-report questionnaires appear to be a feasible method for acquiring pediatric patient-reported experiences of assessment.

Understanding educators' perspectives and experiences of COVID-19 in schools serving children with intellectual/developmental disabilities.

The COVID-19 pandemic has significantly impacted educators, both personally and professionally. However, very little is known about the extent of these impacts among educators' serving children with intellectual and developmental disabilities (IDD). The present study surveyed 230 educators (teachers, staff, and administrators) to assess their wellbeing, concerns during the pandemic, and perceived importance of various COVID-19 school mitigation strategies. Data were gathered May/June of 2021 from two separate school districts, one in the Midwest and the other in the Mid-Atlantic, serving children with IDD. Nearly half of all survey respondents reported poor wellbeing. Almost all educators reported health of themselves, students, and family members was their greatest concern when compared to pandemic-related disruption of their duties or benefits (e.g., not having enough sick time). Most educators felt disinfecting routines, vaccinations, and daily health checks were the most helpful in preventing the spread of COVID-19 in schools, while in-school mask mandates and weekly testing of students and staff were perceived as less helpful. Our findings suggest that efforts are needed to support the wellbeing of educators during these challenging times. When pandemic-related policies and procedures are decided by administrators, our data suggest educators will review decisions within the framework of health and safety of themselves, their students, and families. Understanding this framework may be particularly valuable when considering implementation of COVID-19 policies, like masking and COVID-19 testing, that are less preferred.

Understanding resistant hypertension.

ABSTRACT: Resistant hypertension affects about 17% of the US population. However, it is difficult to diagnose because of multiple factors that influence adequate treatment of BP, including patient lifestyle and comorbidities, improper therapeutic regimens, and secondary mechanisms. Possible causes of resistant hypertension include nonmodulator hypertension, which affects patients who have an inappropriate response to elevated sodium through the renin-angiotensin-aldosterone system. Early identification and frequent follow-up can help patients achieve BP goals more rapidly and may reduce morbidity and mortality associated with complications of hypertension, including cerebrovascular accident, cardiovascular disease, and kidney disease.

Megafire affects stream sediment flux and dissolved organic matter reactivity, but land use dominates nutrient dynamics in semiarid watersheds.

Climate change is causing larger wildfires and more extreme precipitation events in many regions. As these ecological disturbances increasingly coincide, they alter lateral fluxes of sediment, organic matter, and nutrients. Here, we report the stream chemistry response of watersheds in a semiarid region of Utah (USA) that were affected by a megafire followed by an extreme precipitation event in October 2018. We analyzed daily to hourly water samples at 10 stream locations from before the storm event until three weeks after its conclusion for suspended sediment, solute and nutrient concentrations, water isotopes, and dissolved organic matter concentration, optical properties, and reactivity. The megafire caused a ~2,000-fold increase in sediment flux and a ~6,000-fold increase in particulate carbon and nitrogen flux over the course of the storm. Unexpectedly, dissolved organic carbon (DOC) concentration was 2.1-fold higher in burned watersheds, despite the decreased organic matter from the fire. DOC from burned watersheds was 1.3-fold more biodegradable and 2.0-fold more photodegradable than in unburned watersheds based on 28-day dark and light incubations. Regardless of burn status, nutrient concentrations were higher in watersheds with greater urban and agricultural land use. Likewise, human land use had a greater effect than megafire on apparent hydrological residence time, with rapid stormwater signals in urban and agricultural areas but a gradual stormwater pulse in areas without direct human influence. These findings highlight how megafires and intense rainfall increase short-term particulate flux and alter organic matter concentration and characteristics. However, in contrast with previous research, which has largely focused on burned-unburned comparisons in pristine watersheds, we found that direct human influence exerted a primary control on nutrient status. Reducing anthropogenic nutrient sources could therefore increase socioecological resilience of surface water networks to changing wildfire regimes.

Citizen science reveals unexpected solute patterns in semiarid river networks.

Human modification of water and nutrient flows has resulted in widespread degradation of aquatic ecosystems. The resulting global water crisis causes millions of deaths and trillions of USD in economic damages annually. Semiarid regions have been disproportionately affected because of high relative water demand and pollution. Many proven water management strategies are not fully implemented, partially because of a lack of public engagement with freshwater ecosystems. In this context, we organized a large citizen science initiative to quantify nutrient status and cultivate connection in the semiarid watershed of Utah Lake (USA). Working with community members, we collected samples from ~200 locations throughout the 7,640 km2 watershed on a single day in the spring, summer, and fall of 2018. We calculated ecohydrological metrics for nutrients, major ions, and carbon. For most solutes, concentration and leverage (influence on flux) were highest in lowland reaches draining directly to the lake, coincident with urban and agricultural sources. Solute sources were relatively persistent through time for most parameters despite substantial hydrological variation. Carbon, nitrogen, and phosphorus species showed critical source area behavior, with 10-17% of the sites accounting for most of the flux. Unlike temperate watersheds, where spatial variability often decreases with watershed size, longitudinal variability showed an hourglass shape: high variability among headwaters, low variability in mid-order reaches, and high variability in tailwaters. This unexpected pattern was attributable to the distribution of human activity and hydrological complexity associated with return flows, losing river reaches, and diversions in the tailwaters. We conclude that participatory science has great potential to reveal ecohydrological patterns and rehabilitate individual and community relationships with local ecosystems. In this way, such projects represent an opportunity to both understand and improve water quality in diverse socioecological contexts.

Tacrolimus Protects against Age-Associated Microstructural Changes in the Beagle Brain.

The overexpression of calcineurin leads to astrocyte hyperactivation, neuronal death, and inflammation, which are characteristics often associated with pathologic aging and Alzheimer's disease. In this study, we tested the hypothesis that tacrolimus, a calcineurin inhibitor, prevents age-associated microstructural atrophy, which we measured using higher-order diffusion MRI, in the middle-aged beagle brain (n = 30, male and female). We find that tacrolimus reduces hippocampal (p = 0.001) and parahippocampal (p = 0.002) neurite density index, as well as protects against an age-associated increase in the parahippocampal (p = 0.007) orientation dispersion index. Tacrolimus also protects against an age-related decrease in fractional anisotropy in the prefrontal cortex (p < 0.0001). We also show that these microstructural alterations precede cognitive decline and gross atrophy. These results support the idea that calcineurin inhibitors may have the potential to prevent aging-related pathology if administered at middle age.SIGNIFICANCE STATEMENT Hyperactive calcineurin signaling causes neuroinflammation and other neurobiological changes often associated with pathologic aging and Alzheimer's disease (AD). Controlling the expression of calcineurin before gross cognitive deficits are observable might serve as a promising avenue for preventing AD pathology. In this study, we show that the administration of the calcineurin inhibitor, tacrolimus, over 1 year prevents age- and AD-associated microstructural changes in the hippocampus, parahippocampal cortex, and prefrontal cortex of the middle-aged beagle brain, with no noticeable adverse effects. Tacrolimus is already approved by the Food and Drug Administration for use in humans to prevent solid organ transplant rejection, and our results bolster the promise of this drug to prevent AD and aging-related pathology.

Disposition of Proteins and Lipids in Synaptic Membrane Compartments Is Altered in Q175/Q7 Huntington's Disease Mouse Striatum.

Dysfunction at synapses is thought to be an early change contributing to cognitive, psychiatric and motor disturbances in Huntington's disease (HD). In neurons, mutant Huntingtin collects in aggregates and distributes to the same sites as wild-type Huntingtin including on membranes and in synapses. In this study, we investigated the biochemical integrity of synapses in HD mouse striatum. We performed subcellular fractionation of striatal tissue from 2 and 6-month old knock-in Q175/Q7 HD and Q7/Q7 mice. Compared to striata of Q7/Q7 mice, proteins including GLUT3, Na+/K+ ATPase, NMDAR 2b, PSD95, and VGLUT1 had altered distribution in Q175/Q7 HD striata of 6-month old mice but not 2-month old mice. These proteins are found on plasma membranes and pre- and postsynaptic membranes supporting hypotheses that functional changes at synapses contribute to cognitive and behavioral symptoms of HD. Lipidomic analysis of mouse fractions indicated that compared to those of wild-type, fractions 1 and 2 of 6 months Q175/Q7 HD had altered levels of two species of PIP2, a phospholipid involved in synaptic signaling, increased levels of cholesterol ester and decreased cardiolipin species. At 2 months, increased levels of species of acylcarnitine, phosphatidic acid and sphingomyelin were measured. EM analysis showed that the contents of fractions 1 and 2 of Q7/Q7 and Q175/Q7 HD striata had a mix of isolated synaptic vesicles, vesicle filled axon terminals singly or in clusters, and ER and endosome-like membranes. However, those of Q175/Q7 striata contained significantly fewer and larger clumps of particles compared to those of Q7/Q7. Human HD postmortem putamen showed differences from control putamen in subcellular distribution of two proteins (Calnexin and GLUT3). Our biochemical, lipidomic and EM analysis show that the presence of the HD mutation conferred age dependent disruption of localization of synaptic proteins and lipids important for synaptic function. Our data demonstrate concrete biochemical changes suggesting altered integrity of synaptic compartments in HD mice that may mirror changes in HD patients and presage cognitive and psychiatric changes that occur in premanifest HD.