Motives for Cannabis Use and Risky Decision Making Influence Cannabis Use Trajectories in Teens.

The current study will examine the interactive effects of motives for cannabis use (i.e., health or recreational) and risky decision making (DM) on cannabis use trajectories among adolescents. Data from 171 adolescents, aged 14-17 at the initial visit (baseline), were prospectively analyzed across five time points approximately six months apart. Latent growth curve modeling and linear regression analyses were used. We found a significant interactive effect of "recreational motives" and risky DM on the rate of cannabis use over time. Specifically, among those less likely to use cannabis for recreational purposes, riskier DM was associated with a faster increase in the rate of use over time relative to those with lower risky DM. Additionally, a significant main effect showed that those with a greater proclivity to use cannabis for health purposes had higher initial levels of use at baseline and faster increases in the rate of use over time. Regardless of risky DM, using cannabis for health purposes is associated with faster increases in cannabis use escalation. Additionally, risky DM does impact the association between recreational motives for use and cannabis use trajectories. Future work should examine these associations with additional motives for cannabis use that have been previously validated within the literature.

Divergent Molecular Phenotypes in Point Mutations at the Same Residue in Beta-Myosin Heavy Chain Lead to Distinct Cardiomyopathies.

In genetic cardiomyopathies, a frequently described phenomenon is how similar mutations in one protein can lead to discrete clinical phenotypes. One example is illustrated by two mutations in beta myosin heavy chain (ß-MHC) that are linked to hypertrophic cardiomyopathy (HCM) (Ile467Val, I467V) and left ventricular non-compaction (LVNC) (Ile467Thr, I467T). To investigate how these missense mutations lead to independent diseases, we studied the molecular effects of each mutation using recombinant human ß-MHC Subfragment 1 (S1) in in vitro assays. Both HCM-I467V and LVNC-I467T S1 mutations exhibited similar mechanochemical function, including unchanged ATPase and enhanced actin velocity but had opposing effects on the super-relaxed (SRX) state of myosin. HCM-I467V S1 showed a small reduction in the SRX state, shifting myosin to a more actin-available state that may lead to the "gain-of-function" phenotype commonly described in HCM. In contrast, LVNC-I467T significantly increased the population of myosin in the ultra-slow SRX state. Interestingly, molecular dynamics simulations reveal that I467T allosterically disrupts interactions between ADP and the nucleotide-binding pocket, which may result in an increased ADP release rate. This predicted change in ADP release rate may define the enhanced actin velocity measured in LVNC-I467T, but also describe the uncoupled mechanochemical function for this mutation where the enhanced ADP release rate may be sufficient to offset the increased SRX population of myosin. These contrasting molecular effects may lead to contractile dysregulation that initiates LVNC-associated signaling pathways that progress the phenotype. Together, analysis of these mutations provides evidence that phenotypic complexity originates at the molecular level and is critical to understanding disease progression and developing therapies.

Modulating fast skeletal muscle contraction protects skeletal muscle in animal models of Duchenne muscular dystrophy.

Duchenne muscular dystrophy (DMD) is a lethal muscle disease caused by absence of the protein dystrophin, which acts as a structural link between the basal lamina and contractile machinery to stabilize muscle membranes in response to mechanical stress. In DMD, mechanical stress leads to exaggerated membrane injury and fiber breakdown, with fast fibers being the most susceptible to damage. A major contributor to this injury is muscle contraction, controlled by the motor protein myosin. However, how muscle contraction and fast muscle fiber damage contribute to the pathophysiology of DMD has not been well characterized. We explored the role of fast skeletal muscle contraction in DMD with a potentially novel, selective, orally active inhibitor of fast skeletal muscle myosin, EDG-5506. Surprisingly, even modest decreases of contraction (<15%) were sufficient to protect skeletal muscles in dystrophic mdx mice from stress injury. Longer-term treatment also decreased muscle fibrosis in key disease-implicated tissues. Importantly, therapeutic levels of myosin inhibition with EDG-5506 did not detrimentally affect strength or coordination. Finally, in dystrophic dogs, EDG-5506 reversibly reduced circulating muscle injury biomarkers and increased habitual activity. This unexpected biology may represent an important alternative treatment strategy for Duchenne and related myopathies.

Cannabis use and episodic memory performance among adolescents: Moderating effects of depression symptoms and sex.

OBJECTIVE: Cannabis use has been linked to poorer episodic memory. However, little is known about whether depression and sex may interact as potential moderators of this association, particularly among adolescents. The current study addresses this by examining interactions between depression symptoms and sex on the association between cannabis use and episodic memory in a large sample of adolescents. METHOD: Cross-sectional data from 360 adolescents (M age = 17.38, SD = .75) were analyzed at the final assessment wave of a two-year longitudinal study. We used the Drug Use History Questionnaire to assess for lifetime cannabis use, and the Computerized Diagnostic Interview Schedule for Children, Fourth edition to assess the number of depression symptoms in the past year. Subtests from the Wechsler Memory Scale, Fourth Edition and the California Verbal Learning Test, Second Edition were used to assess episodic memory performance. RESULTS: The effect of the three-way interaction among cannabis use, depression symptoms, and sex did not have a significant impact on episodic memory performance. However, follow-up analyses revealed a significant effect of the two-way interaction of cannabis use and depression symptoms on episodic memory, such that associations between cannabis use and episodic memory were only significant at lower and average levels of depression symptoms. CONCLUSIONS: Contrary to our hypotheses, we found that as depression symptoms increased, the negative association between cannabis use and episodic memory diminished. Given the use of a predominantly subsyndromic sample, future studies should attempt to replicate findings among individuals with more severe depression.

ARCHIE++ : A Cloud-Enabled Framework for Conducting AR System Testing in the Wild.

In this paper, we present ARCHIE++, a testing framework for conducting AR system testing and collecting user feedback in the wild. Our system addresses challenges in AR testing practices by aggregating usability feedback data (collected in situ) with system performance data from that same time period. These data packets can then be leveraged to identify edge cases encountered by testers during unconstrained usage scenarios. We begin by presenting a set of current trends in performing human testing of AR systems, identified by reviewing a selection of recent work from leading conferences in mixed reality, human factors, and mobile and pervasive systems. From the trends, we identify a set of challenges to be faced when attempting to adopt these practices to testing in the wild. These challenges are used to inform the design of our framework, which provides a cloud-enabled and device-agnostic way for AR systems developers to improve their knowledge of environmental conditions and to support scalability and reproducibility when testing in the wild. We then present a series of case studies demonstrating how ARCHIE++ can be used to support a range of AR testing scenarios, and demonstrate the limited overhead of the framework through a series of evaluations. We close with additional discussion on the design and utility of ARCHIE++ under various edge conditions.

Genetic versus environmental influences on callous-unemotional traits in preadolescence: The role of parenting and parental psychopathology.

Children with callous-unemotional (CU) traits are at risk for severe conduct problems. While CU traits are moderately heritable, parenting also predicts risk. However, few studies have investigated whether parenting factors (e.g., acceptance, conflict, parental psychopathology) moderate the etiology of CU traits, while accounting for gene-environment correlations. To address this knowledge gap, we used data from 772 twin pairs from the Adolescent Brain and Cognitive Development Study to test bivariate models that explored overlapping etiological influences on CU traits and child reports of their parenting environment. We also used gene-by-environment interaction models to test whether parenting moderated genetic versus environmental influences. There were no overlapping etiological influences on CU traits and parental acceptance, but modest genetic and non-shared environmental overlap between CU traits and family conflict. Parental acceptance and psychopathology moderated non-shared environmental influences, with stronger non-shared environmental influences on CU traits among children who experienced lower parental acceptance and greater parental psychopathology. Family conflict only moderated environmental influences when models did not covary for conduct problems. Parental acceptance and parental psychopathology may be specific environmental protective and risk factors for CU traits, whereas family conflict may represent a general environmental risk factor for both CU traits and conduct problems.

Brief Report: A Pilot Study Examining the Effects of PEERS® for Adolescents Telehealth for Autistic Adolescents.

The COVID-19 pandemic sparked a worldwide transition to providing online services overnight, highlighting the urgent need for empirically supported telehealth interventions. The current study examined the effects of PEERS® for Adolescents Telehealth, an adaptation from the original social skills intervention developed for in-person provision, among 22 autistic adolescents and their caregivers. To evaluate the intervention, caregivers completed questionnaires assessing core autistic features and frequency of get-togethers. Adolescents completed questionnaires measuring social knowledge and frequency of get-togethers. Improvements in social skills knowledge, increased get-togethers, and decreased core autistic symptoms were evident. Preliminary results suggest PEERS® for Adolescents Telehealth improves social competence, as found for the in-person version. Further research exploring the equivalence of telehealth to in-person social skills intervention is recommended.

Targeting the sarcomere in inherited cardiomyopathies.

Variants in >12 genes encoding sarcomeric proteins can cause various cardiomyopathies. The two most common are hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM). Current therapeutics do not target the root causes of these diseases, but attempt to prevent disease progression and/or to manage symptoms. Accordingly, novel approaches are being developed to treat the cardiac muscle dysfunction directly. Challenges to developing therapeutics for these diseases include the diverse mechanisms of pathogenesis, some of which are still being debated and defined. Four small molecules that modulate the myosin motor protein in the cardiac sarcomere have shown great promise in the settings of HCM and DCM, regardless of the underlying genetic pathogenesis, and similar approaches are being developed to target other components of the sarcomere. In the setting of HCM, mavacamten and aficamten bind to the myosin motor and decrease the ATPase activity of myosin. In the setting of DCM, omecamtiv mecarbil and danicamtiv increase myosin activity in cardiac muscle (but omecamtiv mecarbil decreases myosin activity in vitro). In this Review, we discuss the therapeutic strategies to alter sarcomere contractile activity and summarize the data indicating that targeting one protein in the sarcomere can be effective in treating patients with genetic variants in other sarcomeric proteins, as well as in patients with non-sarcomere-based disease.

Remind Me To Remember: A pilot study of a novel smartphone reminder application for older adults with dementia and mild cognitive impairment.

The SmartPrompt is a smartphone-based reminder application informed by a neuropsychological model of functional disability. This laboratory-based pilot study examined the SmartPrompt feasibility, efficacy, and subjective usability using a within-participant, counterbalanced, cross-over design. Ten participants (M age = 80.3 + 8.2; M education = 15.7 + 2.5; 60% female) with mild cognitive impairment or mild dementia completed the Remember to Drink Test, which required preparing a glass of water at four predetermined times, in a SmartPrompt (SP) and Unprompted condition (UP). Written cues and a clock were available in both conditions; however, in the SP, the smartphone presented auditory alarms and visual reminders to obtain the water at specified times and required photo logging. In a separate session, caregivers were trained and tested on configuring the SmartPrompt. Overall, caregivers and participants learned to effectively use the SmartPrompt. Caregivers achieved near-perfect scores on the configuration quiz and responded well to training. Participants completed significantly more Remember to Drink tasks in the SP (93%) than UP (56%); checking the cues/clock decreased by 87% in the SP. Usability ratings were excellent among caregivers and fair among participants. Results indicate that the SmartPrompt holds promise for reducing functional disability in older adults with cognitive difficulties in at-home contexts.

Sex differences in bidirectional associations between conduct problems and cannabis use across two years of adolescence.

BACKGROUND: There is a large body of research that has identified bidirectional associations between conduct problems and cannabis use. Despite growing knowledge regarding comorbidities between conduct problems and cannabis use, it remains unclear whether these findings generalize across both males and females. The current study examined sex differences in longitudinal associations between conduct problems and cannabis use in a predominantly Hispanic sample of adolescents followed over a two-year period. METHODS: Participants were 401 adolescents (89.8% Hispanic, 46% female; Mage = 15.5) taking part in a two-year longitudinal investigation examining the associations between neurocognitive functioning and cannabis use. The sample consisted predominantly of youth selected for risk of cannabis escalation, with 90% reporting using cannabis, nicotine, or alcohol prior to baseline. Negative binomial cross-lagged regressions and simple slope difference tests were used for all analyses. RESULTS: We found support for bidirectional associations between conduct problems and cannabis use, controlling for demographics, covariates, and baseline frequencies. Simple slope difference tests revealed that there was a significant, positive association between baseline cannabis use and subsequent conduct problems among females but not males. In contrast, the association between baseline conduct problems and subsequent frequency of cannabis use did not differ as a function of sex. CONCLUSIONS: Our results underscore the importance of viewing cannabis use as a risk factor for maladjustment rather than solely as a consequence, particularly among female adolescents. Information gained from temporal sequencing of cannabis use and conduct problem symptoms can guide the selection of intervention programs for referred youth.

Chronic Calmodulin-Kinase II Activation Drives Disease Progression in Mutation-Specific Hypertrophic Cardiomyopathy.

BACKGROUND: Although the genetic causes of hypertrophic cardiomyopathy (HCM) are widely recognized, considerable lag in the development of targeted therapeutics has limited interventions to symptom palliation. This is in part attributable to an incomplete understanding of how point mutations trigger pathogenic remodeling. As a further complication, similar mutations within sarcomeric genes can result in differential disease severity, highlighting the need to understand the mechanism of progression at the molecular level. One pathway commonly linked to HCM progression is calcium homeostasis dysregulation, though how specific mutations disrupt calcium homeostasis remains unclear. METHODS: To evaluate the effects of early intervention in calcium homeostasis, we used 2 mouse models of sarcomeric HCM (cardiac troponin T R92L and R92W) with differential myocellular calcium dysregulation and disease presentation. Two modes of intervention were tested: inhibition of the autoactivated calcium-dependent kinase (calmodulin kinase II [CaMKII]) via the AC3I peptide and diltiazem, an L-type calcium channel antagonist. Two-dimensional echocardiography was used to determine cardiac function and left ventricular remodeling, and atrial remodeling was monitored via atrial mass. Sarcoplasmic reticulum Ca2+ATPase activity was measured as an index of myocellular calcium handling and coupled to its regulation via the phosphorylation status of phospholamban. RESULTS: We measured an increase in phosphorylation of CaMKII in R92W animals by 6 months of age, indicating increased autonomous activity of the kinase in these animals. Inhibition of CaMKII led to recovery of diastolic function and partially blunted atrial remodeling in R92W mice. This improved function was coupled to increased sarcoplasmic reticulum Ca2+ATPase activity in the R92W animals despite reduction of CaMKII activation, likely indicating improvement in myocellular calcium handling. In contrast, inhibition of CaMKII in R92L animals led to worsened myocellular calcium handling, remodeling, and function. Diltiazem-HCl arrested diastolic dysfunction progression in R92W animals only, with no improvement in cardiac remodeling in either genotype. CONCLUSIONS: We propose a highly specific, mutation-dependent role of activated CaMKII in HCM progression and a precise therapeutic target for clinical management of HCM in selected cohorts. Moreover, the mutation-specific response elicited with diltiazem highlights the necessity to understand mutation-dependent progression at a molecular level to precisely intervene in disease progression.

Biophysical Derangements in Genetic Cardiomyopathies.

This article focuses on three "bins" that comprise sets of biophysical derangements elicited by cardiomyopathy-associated mutations in the myofilament. Current therapies focus on symptom palliation and do not address the disease at its core. We and others have proposed that a more nuanced classification could lead to direct interventions based on early dysregulation changing the trajectory of disease progression in the preclinical cohort. Continued research is necessary to address the complexity of cardiomyopathic progression and develop efficacious therapeutics.

Atomic resolution probe for allostery in the regulatory thin filament.

Calcium binding and dissociation within the cardiac thin filament (CTF) is a fundamental regulator of normal contraction and relaxation. Although the disruption of this complex, allosterically mediated process has long been implicated in human disease, the precise atomic-level mechanisms remain opaque, greatly hampering the development of novel targeted therapies. To address this question, we used a fully atomistic CTF model to test both Ca(2+) binding strength and the energy required to remove Ca(2+) from the N-lobe binding site in WT and mutant troponin complexes that have been linked to genetic cardiomyopathies. This computational approach is combined with measurements of in vitro Ca(2+) dissociation rates in fully reconstituted WT and cardiac troponin T R92L and R92W thin filaments. These human disease mutations represent known substitutions at the same residue, reside at a significant distance from the calcium binding site in cardiac troponin C, and do not affect either the binding pocket affinity or EF-hand structure of the binding domain. Both have been shown to have significantly different effects on cardiac function in vivo. We now show that these mutations independently alter the interaction between the Ca(2+) ion and cardiac troponin I subunit. This interaction is a previously unidentified mechanism, in which mutations in one protein of a complex indirectly affect a third via structural and dynamic changes in a second to yield a pathogenic change in thin filament function that results in mutation-specific disease states. We can now provide atom-level insight that is potentially highly actionable in drug design.

Liver Kinase B1 complex acts as a novel modifier of myofilament function and localizes to the Z-disk in cardiac myocytes.

Contractile perturbations downstream of Ca(2+) binding to troponin C, the so-called sarcomere-controlled mechanisms, represent the earliest indicators of energy remodeling in the diseased heart [1]. Central to cellular energy "sensing" is the adenosine monophosphate-activated kinase (AMPK) pathway, which is known to directly target myofilament proteins and alter contractility [2-6]. We previously showed that the upstream AMPK kinase, LKB1/MO25/STRAD, impacts myofilament function independently of AMPK [5]. Therefore, we hypothesized that the LKB1 complex associated with myofilament proteins and that alterations in energy signaling modulated targeting or localization of the LKB1 complex to the myofilament. Using an integrated strategy of myofilament mechanics, immunoblot analysis, co-immunoprecipitation, mass spectroscopy, and immunofluorescence, we showed that 1) LKB1 and MO25 associated with myofibrillar proteins, 2) cellular energy stress re-distributed AMPK/LKB1 complex proteins within the sarcomere, and 3) the LKB1 complex localized to the Z-Disk and interacted with cytoskeletal and energy-regulating proteins, including vinculin and ATP Synthase (Complex V). These data represent a novel role for LKB1 complex proteins in myofilament function and myocellular "energy" sensing in the heart.