Behavioral control through the direct, focal silencing of neuronal activity.

The ability to optically stimulate and inhibit neurons has revolutionized neuroscience research. Here, we present a direct, potent, user-friendly chemical approach for optically silencing neurons. We have rendered saxitoxin (STX), a naturally occurring paralytic agent, transiently inert through chemical protection with a previously undisclosed nitrobenzyl-derived photocleavable group. Exposing the caged toxin, STX-bpc, to a brief (5 ms) pulse of light effects rapid release of a potent STX derivative and transient, spatially precise blockade of voltage-gated sodium channels (NaVs). We demonstrate the efficacy of STX-bpc for parametrically manipulating action potentials in mammalian neurons and brain slice. Additionally, we show the effectiveness of this reagent for silencing neural activity by dissecting sensory-evoked swimming in larval zebrafish. Photo-uncaging of STX-bpc is a straightforward method for non-invasive, reversible, spatiotemporally precise neural silencing without the need for genetic access, thus removing barriers for comparative research.

Predictors of Sinonasal Improvement After Highly Effective Modulator Therapy in Adults with Cystic Fibrosis.

OBJECTIVES: The 22-question SinoNasal Outcome Test (SNOT-22) assesses chronic rhinosinusitis (CRS) severity. We aimed to identify predictors of SNOT-22 score improvement following highly effective modulator therapy (HEMT) initiation and to corroborate the SNOT-22 minimal clinically important difference (MCID) in adults with cystic fibrosis (CF). METHODS: Prospective observational data was pooled from four studies across 10 US centers investigating people with CF (PwCF) and CRS. Three studies evaluated HEMT's impact on CRS. For participants enrolled prior to HEMT initiation, SNOT-22 scores were obtained at baseline and after 3-6 months of HEMT. Multivariate regression identified predictors of improvement. Cronbach's alpha and four distribution-based methods were used to assess internal consistency and calculate the MCID of the SNOT-22. RESULTS: A total of 184 PwCF participated with mean baseline SNOT-22 scores ranging from 18.1 to 56.7. Cronbach's alpha was ≥0.90 across sites. Participants at sites with pre- and post-HEMT data reported improvement in SNOT-22 scores after initiating HEMT (all p < 0.05). Worse baseline SNOT-22 score (odds ratio (OR): 1.05, p < 0.001, 95% CI: 1.02-1.08), F508del homozygosity (OR: 4.30, p = 0.040, 95% CI: 1.14-18.99), and absence of prior modulator therapy (OR: 4.99, p = 0.017, 95% CI: 1.39-20.11) were associated with greater SNOT-22 improvement. The mean MCID calculated via distribution-based methods was 8.5. CONCLUSION: Worse baseline sinonasal symptoms, F508del homozygosity, and absence of prior modulator therapy predicted greater improvement after HEMT initiation. The mean MCID for SNOT-22 in PwCF is 8.5 points, similar to non-CF individuals with CRS, and provides a threshold specifically for PwCF. The SNOT-22 has strong internal consistency in PwCF. LEVEL OF EVIDENCE: 3 Laryngoscope, 2024.

Effects of residential socioeconomic polarization on high blood pressure among nursing home residents.

OBJECTIVE: Neighborhood concentration of racial, income, education, and housing deprivation is known to be associated with higher rates of hypertension. The objective of this study is to examine the association between tract-level spatial social polarization and hypertension in a cohort with relatively equal access to health care, a Veterans Affairs nursing home. METHODS: 41,973 long-term care residents aged ≥65 years were matched with tract-level Indices of Concentration at the Extremes across four socioeconomic domains. We modeled high blood pressure against these indices controlling for individual-level cardiovascular confounders. RESULTS: We found participants who had resided in the most disadvantaged quintile had a 1.10 (95% 1.01, 1.19) relative risk of high blood pressure compared to those in the other quintiles for the joint measuring race/ethnicity and income domain. CONCLUSIONS: We achieved our objective by demonstrating that concentrated deprivation is associated with worse cardiovascular outcomes even in a population with equal access to care. Measures that jointly consider economic and racial/ethnic polarization elucidate larger disparities than single domain measures.

Human brain small extracellular vesicles contain selectively packaged, full-length mRNA.

Brain cells release and take up small extracellular vesicles (sEVs) containing bioactive nucleic acids. sEV exchange is hypothesized to contribute to stereotyped spread of neuropathological changes in the diseased brain. We assess mRNA from sEVs of postmortem brain from non-diseased (ND) individuals and those with Alzheimer's disease (AD) using short- and long-read sequencing. sEV transcriptomes are distinct from those of bulk tissue, showing enrichment for genes including mRNAs encoding ribosomal proteins and transposable elements such as human-specific LINE-1 (L1Hs). AD versus ND sEVs show enrichment of inflammation-related mRNAs and depletion of synaptic signaling mRNAs. sEV mRNAs from cultured murine primary neurons, astrocytes, or microglia show similarities to human brain sEVs and reveal cell-type-specific packaging. Approximately 80% of neural sEV transcripts sequenced using long-read sequencing are full length. Motif analyses of sEV-enriched isoforms elucidate RNA-binding proteins that may be associated with sEV loading. Collectively, we show that mRNA in brain sEVs is intact, selectively packaged, and altered in disease.

Patient perspectives on chronic rhinosinusitis in cystic fibrosis: Symptom prioritization in the era of highly effective modulator therapy.

BACKGROUND: Chronic rhinosinusitis (CRS) is common in people with cystic fibrosis (PwCF). Rhinologic symptom prioritization and areas that influence CRS treatment choices, including pursuing endoscopic sinus surgery (ESS), remain understudied. METHODS: Adult PwCF + CRS were enrolled at eight centers into a prospective, observational study (2019-2023). Participants were administered the 22-SinoNasal Outcome Test (SNOT-22) survey and a modified SNOT-22 instrument examining symptom importance. We determined importance rankings for individual symptoms and SNOT-22 symptom importance subdomains in two sets of subgroups-those pursuing ESS versus continuing medical management (CMT), and those on elexacaftor/tezacaftor/ivacaftor (ETI) versus not on ETI. RESULTS: Among 69 participants, the highest priorities were nasal congestion (n = 48, 69.6% important), post-nasal discharge (32, 46.4%), facial pain (29, 43.3%), waking up tired (27, 39.1%), and fatigue (26, 37.7%). Those electing surgery (n = 23) prioritized sleep and psychological dysfunction symptoms compared to those pursuing CMT (n = 49) (sleep median score = 19.0 [interquartile range: 12.0, 25.0] vs. 4.5 [0.0, 12.8]; p < 0.0001; psychological = 17.0 [7.0, 26.0] vs. 7.0 [0.0, 15.8]; p = 0.002). ETI users had comparable SNOT-22 total symptom importance scores to non-ETI users (p = 0.14). Non-ETI users (n = 34) showed a trend toward prioritizing sleep symptoms compared to ETI users (n = 35) (13.0 [2.8, 22.3] vs. 6.0 [2.0, 17.0]; p = 0.055). CONCLUSIONS: Nasal congestion and post-nasal discharge were top priorities reported by PwCF + CRS. Those electing surgery prioritized sleep and psychological symptoms, highlighting their importance in pre-operative discussions. Non-ETI users' prioritization of sleep improvement may highlight their unique disease impact and therapeutic needs; however, additional investigation is required.

Head-mounted central venous access during optical recordings and manipulations of neural activity in mice.

Establishing reliable intravenous catheterization in mice with optical implants allows the combination of neural manipulations and recordings with rapid, time-locked delivery of pharmacological agents. Here we present a procedure for handmade jugular vein catheters designed for head-mounted intravenous access and provide surgical and postoperative guidance for improved survival and patency. A head-mounted vascular access point eliminates the need for a back-mounted button in animals already receiving neural implants, thereby reducing sites of implantation. This protocol, which is readily adoptable by experimenters with previous training and experience in mouse surgery, enables repeated fiber photometry recordings or optogenetic manipulation during drug delivery in adult mice that are awake and behaving, whether head fixed or freely moving. With practice, an experienced surgeon requires ~30 min to perform catheterization on each mouse. Altogether, these techniques facilitate the reliable and repeated delivery of pharmacological agents in mouse models while simultaneously recording at high temporal resolution and/or manipulating neural populations.

Statins, Mortality, and Major Adverse Cardiovascular Events Among US Veterans With Chronic Kidney Disease.

Importance: There are limited data for the utility of statins for primary prevention of atherosclerotic cardiovascular disease (ASCVD) and death in adults with chronic kidney disease (CKD). Objective: To evaluate the association of statin use with all-cause mortality and major adverse cardiovascular events (MACE) among US veterans older than 65 years with CKD stages 3 to 4. Design, Setting, and Participants: This cohort study used a target trial emulation design for statin initiation among veterans with moderate CKD (stages 3 or 4) using nested trials with a propensity weighting approach. Linked Veterans Affairs (VA) Healthcare System, Medicare, and Medicaid data were used. This study considered veterans newly diagnosed with moderate CKD between 2005 and 2015 in the VA, with follow-up through December 31, 2017. Veterans were older than 65 years, within 5 years of CKD diagnosis, had no prior ASCVD or statin use, and had at least 1 clinical visit in the year prior to trial baseline. Eligibility criteria were assessed for each nested trial, and Cox proportional hazards models with bootstrapping were run. Analysis was conducted from July 2021 to October 2023. Exposure: Statin initiation vs none. Main Outcomes and Measures: Primary outcome was all-cause mortality; secondary outcome was time to first MACE (myocardial infarction, transient ischemic attack, stroke, revascularization, or mortality). Results: Included in the analysis were 14 828 veterans. Mean (SD) age at CKD diagnosis was 76.9 (8.2) years, 14 616 (99%) were men, 10 539 (72%) White, and 2568 (17%) Black. After expanding to person-trials and assessing eligibility at each baseline, there were 151 243 person-trials (14 685 individuals) of nonstatin initiators and 2924 person-trials (2924 individuals) of statin initiators included. Propensity score adjustment via overlap weighting with nonparametric bootstrapping resulted in covariate balance, with mean (SD) follow-up of 3.6 (2.7) years. The hazard ratio for all-cause mortality was 0.91 (95% CI, 0.85-0.97) comparing statin initiators to noninitiators. The hazard ratio for MACE was 0.96 (95% CI, 0.91-1.02). Results remained consistent in prespecified subgroup analyses. Conclusions and Relevance: In this target trial emulation of statin initiation in US veterans older than 65 years with CKD stages 3 to 4 and no prior ASCVD, statin initiation was significantly associated with a lower risk of all-cause mortality but not MACE. Results should be confirmed in a randomized clinical trial.

Olfactory loss in people with cystic fibrosis: Community perceptions and impact.

BACKGROUND: Olfactory dysfunction (OD) is prevalent in people with cystic fibrosis (PwCF) and can negatively impact quality-of-life (QOL). This study evaluated perceptions of OD, investigated how OD impacts QOL, and assessed willingness to participate in OD research among the CF community. METHODS: A 21-question survey was distributed through the CF Foundation's Community Voice program in 2023. The survey included questions on olfaction and interest in research. The Brief Questionnaire of Olfactory Disorders (BQOD), a validated person-reported outcome measure to assess QOL, was included. RESULTS: Seventy-six responses were received. Overall, 91% (69/76) reported olfactory problems. Mean BQOD score was 5.0 (standard deviation=4.8), indicating olfactory QOL impairment was present. Ninety-five percent (72/76) reported research on OD is worthwhile and were willing to participate in research. CONCLUSION: Among PwCF, OD and olfactory-specific QOL impairments are prevalent. There is strong interest and willingness to participate in OD research among the CF community.

Structured Moderate Exercise and Biomarkers of Kidney Health in Sedentary Older Adults: The Lifestyle Interventions and Independence for Elders Randomized Clinical Trial.

Rationale & Objective: In the Lifestyle Interventions and Independence for Elders (LIFE) trial, a structured exercise intervention slowed kidney function decline in sedentary older adults. Biomarkers of kidney health could distinguish potential mechanisms for this beneficial effect. Study Design: Randomized controlled trial. Setting & Population: A total of 1,381 sedentary adults aged 70-89 years enrolled in the LIFE trial. Intervention: Structured, 2-year, moderate-intensity exercise intervention versus health education. Outcomes: Physical activity was measured by step count. Primary outcomes were changes in 14 serum and urine biomarkers of kidney health collected at baseline, year 1, and year 2. We determined the effect of randomization on changes in kidney measures and then evaluated observational associations of achieved activity on each measure. Results: Participants assigned to exercise walked on average 291 more steps per day than participants assigned to health education. The intervention was not significantly associated with changes in biomarkers of kidney health. In observational analyses, persons in the highest versus lowest quartile of activity (≥3,470 vs <1,568 steps/day) had significant improvement in urine albumin (mean, -0.22 mg albumin/g urine creatinine [interquartile range (IQR), -0.37 to -0.06]), alpha-1-microglobulin (-0.18 mg/L [-0.28 to -0.08]), trefoil factor-3 (-0.24 pg/mL [-0.35 to -0.13]), epidermal growth factor (0.19 pg/mL [0.06-0.32]), uromodulin (0.06 pg/mL [0.00-0.12]), interleukin 18 (-0.09 pg/mL [-0.15 to -0.03]), neutrophil gelatinase-associated lipocalin (-0.16 pg/mL [-0.24 to -0.07]), monocyte chemoattractant protein-1 (-0.25 pg/mL [-0.36 to -0.14]), clusterin (-0.16 pg/mL [-0.30 to -0.02]), serum tumor necrosis factor receptor-1 (-0.25 mg/dL [-0.39 to -0.11]) and tumor necrosis factor receptor-2 (-0.30 mg/dL [-0.44 to -0.16]). In sensitivity analyses, incremental changes in activity were most impactful on urine interleukin 18 and serum tumor necrosis factor-1. Limitations: The original study was not designed to assess the impact on kidney health. Non-white individuals and patients with advanced chronic kidney disease are underrepresented. Conclusions: Randomization to structured exercise did not improve kidney health at a group level. However, higher exercise was associated with concurrent improvements in biomarkers of glomerular injury, tubular function/repair, tubular injury, generalized inflammation, and tubulointerstitial repair/fibrosis. Plain-Language Summary: In the Lifestyle Interventions For Elders (LIFE) study, randomization to an exercise and physical activity intervention improved the slope of estimated glomerular filtration rate over 2 years compared with health education among older adults. In this study, we sought to determine whether there were specific biomarkers of kidney health that were affected by the exercise and physical activity intervention to investigate potential mechanisms for this positive impact on kidney decline. We found that randomization to the intervention did not improve any of the 14 measures of kidney tubule health. However, in observational analyses, higher activity was independently associated with improvements in several domains, especially tubular injury and generalized inflammation. These results help to clarify the impact of physical activity on kidney health.

Immunogenicity of adjuvanted versus high-dose inactivated influenza vaccines in older adults: a randomized clinical trial.

BACKGROUND: Adjuvanted inactivated influenza vaccine (aIIV) and high-dose inactivated influenza vaccine (HD-IIV) are U.S.-licensed for adults aged ≥ 65 years. This study compared serum hemagglutination inhibition (HAI) antibody titers for the A(H3N2) and A(H1N1)pdm09 and B strains after trivalent aIIV3 and trivalent HD-IIV3 in an older adult population. RESULTS: The immunogenicity population included 342 participants who received aIIV3 and 338 participants who received HD-IIV3. The proportion of participants that seroconverted to A(H3N2) vaccine strains after allV3 (112 participants [32.8%]) was inferior to the proportion of participants that seroconverted after HD-IIV3 (130 participants [38.5%]) at day 29 after vaccination (difference, - 5.8%; 95%CI, - 12.9% to 1.4%). There were no significant differences between the vaccine groups in percent seroconversion to A(H1N1)pdm09 or B vaccine strains, in percent seropositivity for any of the strains, or in post-vaccination GMT for the A(H1N1)pdm09 strain. The GMTs for the post-vaccination A(H3N2) and B strains were higher after HD-IIV than after aIIV3. CONCLUSIONS: Overall immune responses were similar after aIIV3 and HD-IIV3. For the primary outcome, the aIIV3 seroconversion rate for H3N2 did not meet noninferiority criteria compared with HD-IIV3, but the HD-IIV3 seroconversion rate was not statistically superior to the aIIV3 seroconversion rate. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT03183908.

Stakeholder Perspectives on Factors Related to Deprescribing Potentially Inappropriate Medications in Older Adults Receiving Dialysis.

BACKGROUND: Potentially inappropriate medications, or medications that generally carry more risk of harm than benefit in older adults, are commonly prescribed to older adults receiving dialysis. Deprescribing, a systematic approach to reducing or stopping a medication, is a potential solution to limit potentially inappropriate medications use. Our objective was to identify clinicians and patient perspectives on factors related to deprescribing to inform design of a deprescribing program for dialysis clinics. METHODS: We conducted rapid qualitative analysis of semistructured interviews and focus groups with clinicians (dialysis clinicians, primary care providers, and pharmacists) and patients (adults receiving hemodialysis aged 65 years or older and those aged 55-64 years who were prefrail or frail) from March 2019 to December 2020. RESULTS: We interviewed 76 participants (53 clinicians [eight focus groups and 11 interviews] and 23 patients). Among clinicians, 24 worked in dialysis clinics, 18 worked in primary care, and 11 were pharmacists. Among patients, 13 (56%) were aged 65 years or older, 14 (61%) were Black race, and 16 (70%) reported taking at least one potentially inappropriate medication. We identified four themes (and corresponding subthemes) of contextual factors related to deprescribing potentially inappropriate medications: ( 1 ) system-level barriers to deprescribing (limited electronic medical record interoperability, time constraints and competing priorities), ( 2 ) undefined comanagement among clinicians (unclear role delineation, clinician caution about prescriber boundaries), ( 3 ) limited knowledge about potentially inappropriate medications (knowledge limitations among clinicians and patients), and ( 4 ) patients prioritize symptom control over potential harm (clinicians expect resistance to deprescribing, patient weigh risks and benefits). CONCLUSIONS: Challenges to integration of deprescribing into dialysis clinics included siloed health systems, time constraints, comanagement behaviors, and clinician and patient knowledge and attitudes toward deprescribing.

Complementary and Alternative Medicine Use in Patients With Cancer and Immigration Background.

PURPOSE: Studies have shown that patients with cancer are more likely to use complementary and alternative medicine (CAM) than noncancer patients for symptom relief and hope. We aimed to evaluate factors of race, ethnic groups, and immigration status in attitude of patients with cancer in seeking out CAM. PATIENTS AND METHODS: This is a prospective questionnaire study where information on demographics, cancer information, race/ethnicity, immigration duration, and psychosocial factors was correlated with the CAM use in a community cancer center located in the borough of Brooklyn, at New York City. RESULTS: Among 658 patients, the prevalence of CAM use was 66.11%. CAM use was 71.98% in females and 54.34% in males (P = .113 × 10-4). Patients of African descent had higher CAM use (72.73%) than the White patients (63.53%; P = .0371). There was no difference of CAM use between the US born (68.77%) and the immigrants (63.98%, P = .199) as a whole; however, comparing with the US born (66.50%), Asian-born immigrants had lower CAM use (53.77%, P = .0161), whereas Latin-American born had a numerical trend toward higher CAM use (74.83%, P = .0608). The number of years of living in the United States was not associated with more CAM use. Prayer and spirituality was the most common CAM subtype used (25.91%). There was no difference in CAM use in the respective non-White ethnic groups whether they were US born or non-US born. CONCLUSION: In this cohort of patients with cancer enriched with immigration background, CAM use was the highest in African American patients. The use of CAM in the non-White patients was associated with their ethnic background, regardless whether they were US born or not. Cultural roots appeared to be a strong influencing factor for the usage of CAM.

Decision-making about dialysis: Beyond just dialysis or death.

Nearly half of the persons receiving dialysis in the United States are aged 65 years or older. Kidney failure occurs most frequently in older adults, and typically triggers a discussion regarding dialysis treatment. In this Special Article, we describe the journey of Mr. Howard Russell, an older adult who experienced kidney failure and underwent dialysis. Using the experience of Mr. Russell, we illustrate the complexity of dialysis decision-making, including how disease trajectory and health policy can potentially impede older adults from achieving "what matters." Our intent is to provide guidance regarding these barriers and support to clinicians who are sharing similar journeys with older adults making decisions about dialysis. Based on Mr. Russell's journey, we suggest that when discussing dialysis with an older adult, four points be considered: (1) recognize if dialysis is needed long-term; (2) understand what matters for the older adult; (3) sync the treatment plan when what matters changes; and (4) set up with resources for kidney failure, which is limited but evolving.

Effect of Long-term Exercise Training on Physical Performance and Cardiorespiratory Function in Adults With CKD: A Randomized Controlled Trial.

RATIONALE & OBJECTIVE: The safety and efficacy of long-term exercise training in reducing physical functional loss in older adults with advanced CKD and comorbidity is uncertain. STUDY DESIGN: Multicenter, parallel group, randomized controlled trial. SETTINGS & PARTICIPANTS: Adults 55 years and older with estimated glomerular filtration rate (eGFR) of 15 to <45 mL/min/1.73 m2 enrolled from centers in Baltimore and Boston. INTERVENTION: Twelve months of in-center supervised exercise training incorporating majority aerobic but also muscle strengthening activities or a group health education control intervention, randomly assigned in 1:1 ratio. OUTCOME: Primary outcomes were cardiorespiratory fitness and submaximal gait at 6 and 12 months quantified by peak oxygen consumption (Vo2peak) on graded exercise treadmill test and distance walked on the 6-minute walk test, respectively. Secondary outcomes were changes in lower extremity function, eGFR, albuminuria, glycemia, blood pressure, and body mass index. RESULTS: Among 99 participants, the mean age was 68 years, 62% were African American, and the mean eGFR was 33 mL/min/1.73 m2; 59% had diabetes, and 29% had coronary artery disease. Among those randomized to exercise, 59% of exercise sessions were attended in the initial 6 months. Exercise was well tolerated without excess occurrence of adverse events. At 6 months, aerobic capacity was higher among exercise participants (17.9 ± 5.5 vs 15.9 ± 7.0 mL/kg/min, P = 0.03), but the differences were not sustained at 12 months. The 6-minute walk distance improved more in the exercise group (adjusted difference: 98 feet [P = 0.02; P = 0.03 for treatment-by-time interaction]). The exercise group had greater improvements on the Timed Up and Go Test (P = 0.04) but not the Short Physical Performance Battery (P = 0.8). LIMITATIONS: Planned sample size was not reached. Loss to follow-up and dropout were greater than anticipated. CONCLUSIONS: Among adults aged ≥55 years with CKD stages 3b-4 and a high level of medical comorbidity, a 12-month program of in-center aerobic and resistance exercise training was safe and associated with improvements in physical functioning. FUNDING: Government grants (National Institutes of Health). TRIAL REGISTRATION: Registered at ClinicalTrials.gov with study number NCT01462097.

Longitudinal Evaluation of Antibody Persistence in Mother-Infant Dyads After Severe Acute Respiratory Syndrome Coronavirus 2 Infection in Pregnancy.

BACKGROUND: There are limited data on how coronavirus disease 2019 (COVID-19) severity, timing of infection, and subsequent vaccination impact transplacental transfer and persistence of maternal and infant antibodies. METHODS: In a longitudinal cohort of pregnant women with polymerase chain reaction-confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, maternal/infant sera were collected at enrollment, delivery/birth, and 6 months. Anti-SARS-CoV-2 spike immunoglobulin (Ig)G, IgM, and IgA were measured by enzyme-linked immunosorbent assay. RESULTS: Two-hundred fifty-six pregnant women and 135 infants were enrolled; 148 maternal and 122 neonatal specimens were collected at delivery/birth; 45 maternal and 48 infant specimens were collected at 6 months. Sixty-eight percent of women produced all anti-SARS-CoV-2 isotypes at delivery (IgG, IgM, IgA); 96% had at least 1 isotype. Symptomatic disease and vaccination before delivery were associated with higher maternal IgG at labor and delivery. Detectable IgG in infants dropped from 78% at birth to 52% at 6 months. In the multivariate analysis evaluating factors associated with detectable IgG in infants at delivery, significant predictors were 3rd trimester infection (odds ratio [OR] = 4.0), mild/moderate disease (OR = 4.8), severe/critical disease (OR = 6.3), and maternal vaccination before delivery (OR = 18.8). No factors were significant in the multivariate analysis at 6 months postpartum. CONCLUSIONS: Vaccination in pregnancy post-COVID-19 recovery is a strategy for boosting antibodies in mother-infant dyads.

An inhibitory brainstem input to dopamine neurons encodes nicotine aversion.

Nicotine stimulates the dopamine (DA) system, which is essential for its rewarding effect. Nicotine is also aversive at high doses; yet, our knowledge about nicotine's dose-dependent effects on DA circuits remains limited. Here, we demonstrate that high doses of nicotine, which induce aversion-related behavior in mice, cause biphasic inhibitory and excitatory responses in VTA DA neurons that can be dissociated by distinct projections to lateral and medial nucleus accumben subregions, respectively. Guided by computational modeling, we performed a pharmacological investigation to establish that inhibitory effects of aversive nicotine involve desensitization of α4ß2 and activation of α7 nicotinic acetylcholine receptors. We identify α7-dependent activation of upstream GABA neurons in the laterodorsal tegmentum (LDT) as a key regulator of heterogeneous DA release following aversive nicotine. Finally, inhibition of LDT GABA terminals in VTA prevents nicotine aversion. Together, our findings provide a mechanistic circuit-level understanding of nicotine's dose-dependent effects on reward and aversion.

Transient food insecurity during the juvenile-adolescent period affects adult weight, cognitive flexibility, and dopamine neurobiology.

A major challenge for neuroscience, public health, and evolutionary biology is to understand the effects of scarcity and uncertainty on the developing brain. Currently, a significant fraction of children and adolescents worldwide experience insecure access to food. The goal of our work was to test in mice whether the transient experience of insecure versus secure access to food during the juvenile-adolescent period produced lasting differences in learning, decision-making, and the dopamine system in adulthood. We manipulated feeding schedules in mice from postnatal day (P)21 to P40 as food insecure or ad libitum and found that when tested in adulthood (after P60), males with different developmental feeding history showed significant differences in multiple metrics of cognitive flexibility in learning and decision-making. Adult females with different developmental feeding history showed no differences in cognitive flexibility but did show significant differences in adult weight. We next applied reinforcement learning models to these behavioral data. The best fit models suggested that in males, developmental feeding history altered how mice updated their behavior after negative outcomes. This effect was sensitive to task context and reward contingencies. Consistent with these results, in males, we found that the two feeding history groups showed significant differences in the AMPAR/NMDAR ratio of excitatory synapses on nucleus-accumbens-projecting midbrain dopamine neurons and evoked dopamine release in dorsal striatal targets. Together, these data show in a rodent model that transient differences in feeding history in the juvenile-adolescent period can have significant impacts on adult weight, learning, decision-making, and dopamine neurobiology.

The Impact of Care Partners on the Mobility of Older Adults Receiving Hemodialysis.

Rationale & Objective: Many older adults receiving hemodialysis have mobility limitations and rely on care partners, yet data are sparse regarding the support provided by care partners. Our aim was to examine how care partners support the mobility of an older adult receiving hemodialysis. Study Design: Qualitative study. Setting & Participants: Using purposive sampling, we recruited persons aged 60 years or more receiving maintenance hemodialysis and care partners aged 18 years or more who were providing support to an older adult receiving hemodialysis. We conducted in-person semi-structured interviews about mobility with each individual. Analytical Approach: We conducted descriptive and focused coding of interview transcripts and employed thematic analysis. Our outcome was to describe perceived mobility supports provided by care partners using qualitative themes. Results: We enrolled 31 older adults receiving hemodialysis (42% women, 68% Black) with a mean age of 73 ± 8 years and a mean dialysis duration of 4.6 ± 3.5 years. Of these, 87% of patients used assistive devices and 90% had care partners. We enrolled 12 care partners (75% women, 33% Black) with a mean age of 54 ± 16 years. From our patient and care partner interviews, we found three themes: (1) what care partners see, (2) what care partners do, and (3) what care partners feel. Regarding what they see, care partners witness a decline in patient mobility. Regarding what they do, care partners guide and facilitate activities and manage others who also assist. Regarding what they feel, care partners respect the patient's autonomy but experience frustration and worry about the patient's future mobility. Limitations: Modest sample size; single geographic area. Conclusions: In older adults receiving hemodialysis, care partners observe a decline in mobility and provide support for mobility. They respect the patient's autonomy but worry about future mobility losses. Future research should incorporate care partners in interventions that address mobility in older adults receiving hemodialysis.