Shuttle peptide delivers base editor RNPs to rhesus monkey airway epithelial cells in vivo.

Gene editing strategies for cystic fibrosis are challenged by the complex barrier properties of airway epithelia. We previously reported that the amphiphilic S10 shuttle peptide non-covalently combined with CRISPR-associated (Cas) ribonucleoprotein (RNP) enabled editing of human and mouse airway epithelial cells. Here, we derive the S315 peptide as an improvement over S10 in delivering base editor RNP. Following intratracheal aerosol delivery of Cy5-labeled peptide in rhesus macaques, we confirm delivery throughout the respiratory tract. Subsequently, we target CCR5 with co-administration of ABE8e-Cas9 RNP and S315. We achieve editing efficiencies of up-to 5.3% in rhesus airway epithelia. Moreover, we document persistence of edited epithelia for up to 12 months in mice. Finally, delivery of ABE8e-Cas9 targeting the CFTR R553X mutation restores anion channel function in cultured human airway epithelia. These results demonstrate the therapeutic potential of base editor delivery with S315 to functionally correct the CFTR R553X mutation in respiratory epithelia.

Independent factor structure replication of the SAEBRS teacher and student scales.

The purpose of this study was to independently assess the best-fitting factor models of the Social, Academic, and Emotional Behavior Risk Screener (SAEBRS) student and teacher forms. To do this, we used previously published confirmatory factor analysis procedures (see von der Embse, Iaccarino, et al., 2017) in an attempt to replicate the factor structure. Unidimensional, correlated-factors, higher order, bifactor, and bifactor with correlated residuals models were assessed. The bifactor model yielded the best fit for the student, χ² = 286.58, p < .001, χ²/df = 1.91, RMSEA = .070, CFI = .839, TLI = .796, WRMR = 1.047, and teacher forms, χ² = 502.44, p < .001, χ²/df = 3.78, RMSEA = .095, CFI = .977, TLI = .971, WRMR = 1.193. Nonetheless, the majority of the fit statistics indicated an adequate fit for the student form. The SAEBRS Total Behavior score was found to have the greatest reliability for the student, ω = .77, ωH = .76, and teacher forms, ω = .93, ωH = .86, as well. Model, factor, and item-level indexes indicated mixed support for unidimensionality versus multidimensionality on student and teacher forms. Generally, it is implicated that the SAEBRS overall score was the soundest score for screening risk with the student and teacher forms. However, future investigations could consider a wider variety of methods to test competing factor structures. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

A retrotransposon storm marks clinical phenoconversion to late-onset Alzheimer's disease.

Recent reports have suggested that the reactivation of otherwise transcriptionally silent transposable elements (TEs) might induce brain degeneration, either by dysregulating the expression of genes and pathways implicated in cognitive decline and dementia or through the induction of immune-mediated neuroinflammation resulting in the elimination of neural and glial cells. In the work we present here, we test the hypothesis that differentially expressed TEs in blood could be used as biomarkers of cognitive decline and development of AD. To this aim, we used a sample of aging subjects (age > 70) that developed late-onset Alzheimer's disease (LOAD) over a relatively short period of time (12-48 months), for which blood was available before and after their phenoconversion, and a group of cognitive stable subjects as controls. We applied our developed and validated customized pipeline that allows the identification, characterization, and quantification of the differentially expressed (DE) TEs before and after the onset of manifest LOAD, through analyses of RNA-Seq data. We compared the level of DE TEs within more than 600,000 TE-mapping RNA transcripts from 25 individuals, whose specimens we obtained before and after their phenotypic conversion (phenoconversion) to LOAD, and discovered that 1790 TE transcripts showed significant expression differences between these two timepoints (logFC ± 1.5, logCMP > 5.3, nominal p value < 0.01). These DE transcripts mapped both over- and under-expressed TE elements. Occurring before the clinical phenoconversion, this TE storm features significant increases in DE transcripts of LINEs, LTRs, and SVAs, while those for SINEs are significantly depleted. These dysregulations end with signs of manifest LOAD. This set of highly DE transcripts generates a TE transcriptional profile that accurately discriminates the before and after phenoconversion states of these subjects. Our findings suggest that a storm of DE TEs occurs before phenoconversion from normal cognition to manifest LOAD in risk individuals compared to controls, and may provide useful blood-based biomarkers for heralding such a clinical transition, also suggesting that TEs can indeed participate in the complex process of neurodegeneration.

Beyond amyloid: Immune, cerebrovascular, and metabolic contributions to Alzheimer disease in people with Down syndrome.

People with Down syndrome (DS) have increased risk of Alzheimer disease (AD), presumably conferred through genetic predispositions arising from trisomy 21. These predispositions necessarily include triplication of the amyloid precursor protein (APP), but also other Ch21 genes that confer risk directly or through interactions with genes on other chromosomes. We discuss evidence that multiple genes on chromosome 21 are associated with metabolic dysfunction in DS. The resulting dysregulated pathways involve the immune system, leading to chronic inflammation; the cerebrovascular system, leading to disruption of the blood brain barrier (BBB); and cellular energy metabolism, promoting increased oxidative stress. In combination, these disruptions may produce a precarious biological milieu that, in the presence of accumulating amyloid, drives the pathophysiological cascade of AD in people with DS. Critically, mechanistic drivers of this dysfunction may be targetable in future clinical trials of pharmaceutical and/or lifestyle interventions.

Cement venogram as a harbinger of methacrylate embolism after kyphoplasty: A case series.

Vertebral compression fractures remain an important cause of pain and debility. Intractable pain may be approached with vertebral kyphoplasty. We herein present a case of symptomatic pulmonary cement embolism following kyphoplasty. Discovery of a paravertebral cement venogram at the time of this procedure prompted a case series review of our institutional experience with kyphoplasty. We found that cement embolization, whether symptomatic or discovered incidentally, was universally associated with a cement venogram at the site of vertebroplasty. We propose that a cement venogram be viewed as a harbinger of cement pulmonary embolism and this possibility be considered in patients with an existing intracardiac shunt or who present with new respiratory symptoms soon after kyphoplasty.

Early Lung Disease Exhibits Bacteria-Dependent and -Independent Abnormalities in Cystic Fibrosis Pigs.

Rationale: Although it is clear that cystic fibrosis (CF) airway disease begins at a very young age, the early and subsequent steps in disease pathogenesis and the relative contribution of infection, mucus, and inflammation are not well understood. Objectives: As one approach to assessing the early contribution of infection, we tested the hypothesis that early and continuous antibiotics would decrease the airway bacterial burden. We believed that, if they do, this might reveal aspects of the disease that are more or less sensitive to decreasing infection. Methods: Three groups of pigs were studied from birth until ∼3 weeks of age: 1) wild-type, 2) CF, and 3) CF pigs treated continuously with broad-spectrum antibiotics from birth until study completion. Disease was assessed with chest computed tomography, histopathology, microbiology, and BAL. Measurements and Main Results: Disease was present by 3 weeks of age in CF pigs. Continuous antibiotics from birth improved chest computed tomography imaging abnormalities and airway mucus accumulation but not airway inflammation in the CF pig model. However, reducing bacterial infection did not improve two disease features already present at birth in CF pigs: air trapping and submucosal gland duct plugging. In the CF sinuses, antibiotics did not prevent the development of infection or disease or the number of bacteria but did alter the bacterial species. Conclusions: These findings suggest that CF airway disease begins immediately after birth and that early and continuous antibiotics impact some, but not all, aspects of CF lung disease development.

Metabolic correlates of prevalent mild cognitive impairment and Alzheimer's disease in adults with Down syndrome.

INTRODUCTION: Disruption of metabolic function is a recognized feature of late onset Alzheimer's disease (LOAD). We sought to determine whether similar metabolic pathways are implicated in adults with Down syndrome (DS) who have increased risk for Alzheimer's disease (AD). METHODS: We examined peripheral blood from 292 participants with DS who completed baseline assessments in the Alzheimer's Biomarkers Consortium-Down Syndrome (ABC-DS) using untargeted mass spectrometry (MS). Our sample included 38 individuals who met consensus criteria for AD (DS-AD), 43 who met criteria for mild cognitive impairment (DS-MCI), and 211 who were cognitively unaffected and stable (CS). RESULTS: We measured relative abundance of 8,805 features using MS and 180 putative metabolites were differentially expressed (DE) among the groups at false discovery rate-corrected q< 0.05. From the DE features, a nine-feature classifier model classified the CS and DS-AD groups with receiver operating characteristic area under the curve (ROC AUC) of 0.86 and a two-feature model classified the DS-MCI and DS-AD groups with ROC AUC of 0.88. Metabolite set enrichment analysis across the three groups suggested alterations in fatty acid and carbohydrate metabolism. DISCUSSION: Our results reveal metabolic alterations in DS-AD that are similar to those seen in LOAD. The pattern of results in this cross-sectional DS cohort suggests a dynamic time course of metabolic dysregulation which evolves with clinical progression from non-demented, to MCI, to AD. Metabolomic markers may be useful for staging progression of DS-AD.

Plasma metabolites related to cellular energy metabolism are altered in adults with Down syndrome and Alzheimer's disease.

Down syndrome (DS) is a well-known neurodevelopmental disorder most commonly caused by trisomy of chromosome 21. Because individuals with DS almost universally develop heavy amyloid burden and Alzheimer's disease (AD), biomarker discovery in this population may be extremely fruitful. Moreover, any AD biomarker in DS that does not directly involve amyloid pathology may be of high value for understanding broader mechanisms of AD generalizable to the neurotypical population. In this retrospective biomarker discovery study, we examined banked peripheral plasma samples from 78 individuals with DS who met clinical criteria for AD at the time of the blood draw (DS-AD) and 68 individuals with DS who did not (DS-NAD). We measured the relative abundance of approximately 5,000 putative features in the plasma using untargeted mass spectrometry (MS). We found significantly higher levels of a peak putatively annotated as lactic acid in the DS-AD group (q = .014), a finding confirmed using targeted MS (q = .011). Because lactate is the terminal product of glycolysis and subsequent lactic acid fermentation, we performed additional targeted MS focusing on central carbon metabolism which revealed significantly increased levels of pyruvic (q = .03) and methyladipic (q = .03) acids in addition to significantly lower levels of uridine (q = .007) in the DS-AD group. These data suggest that AD in DS is accompanied by a shift from aerobic respiration toward the less efficient fermentative metabolism and that bioenergetically derived metabolites observable in peripheral blood may be useful for detecting this shift.

Differentiation of non-small cell lung cancer and histoplasmosis pulmonary nodules: insights from radiomics model performance compared with clinician observers.

BACKGROUND: Histoplasmosis pulmonary nodules often present in computed tomography (CT) imaging with characteristics suspicious for lung cancer. This presents a work-up decision issue for clinicians in regions where histoplasmosis is an endemic fungal infection, when a nodule suspicious for lung cancer is detected. We hypothesize the application of radiomic features extracted from pulmonary nodules and perinodular parenchyma could accurately distinguish between suspicious histoplasmosis lung nodules and non-small cell lung cancer (NSCLC). METHODS: A retrospective clinical cohort of pulmonary nodules with a confirmed diagnosis of histoplasmosis or NSCLC was collected from the University of Iowa Hospitals and Clincs. Radiomic features were extracted describing characteristics of the nodule and perinodular parenchyma regions and used to build a machine learning tool. These cases were assessed by four expert clinicians who gave a blinded risk prediction for NSCLC. Tool and observer performance were assessed by calculating the area under the curve for the receiver operating characteristic (AUC-ROC) and interclass correlation coefficient (ICC). RESULTS: A cohort of 71 subjects with confirmed histopathology (40 NSCLC, 31 histoplasmosis) were case-matched based on age, sex, and smoking history. Superior performance (AUC-ROC =0.89) was demonstrated using leave-one-subject out validation in the tool that incorporated radiomics from the nodule and perinodular parenchyma region extended to 100% nodule diameter. Observers had perfect intra-repeatability (ICC =1.0) and demonstrated fair inter-reader variability (ICC =0.52). CONCLUSIONS: Radiomics have potential utility in the challenging task of differentiation between lung cancer and histoplasmosis. Expert clinician readers have high intra-repeatability but demonstrated inter-reader variability which could provide context for a supplemental radiomics-based tool.

Predicting School Suspension Risk from Eighth through Tenth Grade Using the Strengths and Difficulties Questionnaire.

The current study examined (1) if the Strengths and Difficulties Questionnaire (SDQ) would yield alternative factor structures related to either symptoms or strengths with early adolescent students when an exploratory factor analysis (EFA) is used; (2) which scales best predicted suspensions of typically developing early adolescents; and (3) what cut-off scores were useful for identifying youth at risk for suspensions. The current study included 321 parent-student dyads, who were followed from the middle of eighth grade until the end of tenth grade. A symptoms-based EFA yielded three factors: Misbehavior, Isolation, and Agitation. A strength-based EFA yielded three factors, as, well: Emotional, Social, and Moral competence. Logistic regression path analyses were used to predict risk of any suspension at the end of eighth, ninth, and tenth grades. The predictor variables were the original SDQ Conduct Problems and Hyperactivity scales in one model, the Misbehavior and Agitation scales in a second model, and the Emotional and Moral competence scales in the third model. Only the Misbehavior scale consistently predicted suspensions across each grade (b = .27, OR = 1.32, p < .001; b = .15, OR = 1.18, p = .029; b = .17, OR = 1.18, p = .029, respectively). For the Misbehavior scale, cut-off scores were established that reflected the 75th and 90th percentile; however, each cut-off demonstrated strengths and weaknesses for identifying at-risk students. The expectation of screening to identify youth at-risk for suspensions, a complex school discipline decision, is discussed.

Potential Metabolomic Linkage in Blood between Parkinson's Disease and Traumatic Brain Injury.

The etiologic basis for sporadic forms of neurodegenerative diseases has been elusive but likely represents the product of genetic predisposition and various environmental factors. Specific gene-environment interactions have become more salient owing, in part, to the elucidation of epigenetic mechanisms and their impact on health and disease. The linkage between traumatic brain injury (TBI) and Parkinson's disease (PD) is one such association that currently lacks a mechanistic basis. Herein, we present preliminary blood-based metabolomic evidence in support of potential association between TBI and PD. Using untargeted and targeted high-performance liquid chromatography-mass spectrometry we identified metabolomic biomarker profiles in a cohort of symptomatic mild TBI (mTBI) subjects (n = 75) 3⁻12 months following injury (subacute) and TBI controls (n = 20), and a PD cohort with known PD (n = 20) or PD dementia (PDD) (n = 20) and PD controls (n = 20). Surprisingly, blood glutamic acid levels in both the subacute mTBI (increased) and PD/PDD (decreased) groups were notably altered from control levels. The observed changes in blood glutamic acid levels in mTBI and PD/PDD are discussed in relation to other metabolite profiling studies. Should our preliminary results be replicated in comparable metabolomic investigations of TBI and PD cohorts, they may contribute to an "excitotoxic" linkage between TBI and PD/PDD.

Alabama Parenting Questionnaire-9: Longitudinal Measurement Invariance Across Parents and Youth During the Transition to High School.

The Alabama Parenting Questionnaire nine-item short form (APQ-9) is an often used assessment of parenting in research and applied settings. It uses parent and youth ratings for three scales: Positive Parenting, Inconsistent Discipline, and Poor Supervision. The purpose of this study is to examine the longitudinal invariance of the APQ-9 for both parents and youth, and the multigroup invariance between parents and youth during the transition from middle school to high school. Parent and youth longitudinal configural, metric, and scalar invariance for the APQ-9 were supported when tested separately. However, the multigroup invariance tests indicated that scalar invariance was not achieved between parent and youth ratings. Essentially, parent and youth mean scores for Positive Parenting, Inconsistent Discipline, and Poor Supervision can be independently compared across the transition from middle school to high school. However, comparing parent and youth scores across the APQ-9 scales may not be meaningful.

Randomized trial of parent training to prevent adolescent problem behaviors during the high school transition.

This randomized controlled trial tested a widely used general parent training program, Common Sense Parenting (CSP), with low-income 8th graders and their families to support a positive transition to high school. The program was tested in its original 6-session format and in a modified format (CSP-Plus), which added 2 sessions that included adolescents. Over 2 annual cohorts, 321 families were enrolled and randomly assigned to either the CSP, CSP-Plus, or minimal-contact control condition. Pretest, posttest, 1-year follow-up, and 2-year follow-up survey data on parenting as well as youth school bonding, social skills, and problem behaviors were collected from parents and youth (94% retention). Extending prior examinations of posttest outcomes, intent-to-treat regression analyses tested for intervention effects at the 2 follow-up assessments, and growth curve analyses examined experimental condition differences in yearly change across time. Separate exploratory tests of moderation by youth gender, youth conduct problems, and family economic hardship also were conducted. Out of 52 regression models predicting 1- and 2-year follow-up outcomes, only 2 out of 104 possible intervention effects were statistically significant. No statistically significant intervention effects were found in the growth curve analyses. Tests of moderation also showed few statistically significant effects. Because CSP already is in widespread use, findings have direct implications for practice. Specifically, findings suggest that the program may not be efficacious with parents of adolescents in a selective prevention context and may reveal the limits of brief, general parent training for achieving outcomes with parents of adolescents. (PsycINFO Database Record

Acute administration of ivacaftor to people with cystic fibrosis and a G551D-CFTR mutation reveals smooth muscle abnormalities.

BACKGROUND: Airflow obstruction is common in cystic fibrosis (CF), yet the underlying pathogenesis remains incompletely understood. People with CF often exhibit airway hyperresponsiveness, CF transmembrane conductance regulator (CFTR) is present in airway smooth muscle (ASM), and ASM from newborn CF pigs has increased contractile tone, suggesting that loss of CFTR causes a primary defect in ASM function. We hypothesized that restoring CFTR activity would decrease smooth muscle tone in people with CF. METHODS: To increase or potentiate CFTR function, we administered ivacaftor to 12 adults with CF with the G551D-CFTR mutation; ivacaftor stimulates G551D-CFTR function. We studied people before and immediately after initiation of ivacaftor (48 hours) to minimize secondary consequences of CFTR restoration. We tested smooth muscle function by investigating spirometry, airway distensibility, and vascular tone. RESULTS: Ivacaftor rapidly restored CFTR function, indicated by reduced sweat chloride concentration. Airflow obstruction and air trapping also improved. Airway distensibility increased in airways less than 4.5 mm but not in larger-sized airways. To assess smooth muscle function in a tissue outside the lung, we measured vascular pulse wave velocity (PWV) and augmentation index, which both decreased following CFTR potentiation. Finally, change in distensibility of <4.5-mm airways correlated with changes in PWV. CONCLUSIONS: Acute CFTR potentiation provided a unique opportunity to investigate CFTR-dependent mechanisms of CF pathogenesis. The rapid effects of ivacaftor on airway distensibility and vascular tone suggest that CFTR dysfunction may directly cause increased smooth muscle tone in people with CF and that ivacaftor may relax smooth muscle. FUNDING: This work was funded in part from an unrestricted grant from the Vertex Investigator-Initiated Studies Program.

Prevalence of marijuana and other substance use before and after Washington State's change from legal medical marijuana to legal medical and nonmedical marijuana: Cohort comparisons in a sample of adolescents.

BACKGROUND: A growing number of states have new legislation extending prior legalization of medical marijuana by allowing nonmedical marijuana use for adults. The potential influence of this change in legislation on adolescent marijuana and other substance use (e.g., spillover or substitution effects) is uncertain. We capitalize on an ongoing study to explore the prevalence of marijuana and other substance use in 2 cohorts of adolescents who experienced the nonmedical marijuana law change in Washington State at different ages. METHODS: Participants were 8th graders enrolled in targeted Tacoma, Washington public schools and recruited in 2 consecutive annual cohorts. The analysis sample was 238 students who completed a baseline survey in the 8th grade and a follow-up survey after the 9th grade. Between the 2 assessments, the second cohort experienced the Washington State nonmedical marijuana law change, whereas the first cohort did not. Self-report survey data on lifetime and past-month marijuana, cigarette, and alcohol use were collected. RESULTS: Multivariate multilevel modeling showed that cohort differences in the likelihood of marijuana use were significantly different from those for cigarette and alcohol use at follow-up (adjusting for baseline substance initiation). Marijuana use was higher for the second cohort than the first cohort, but this difference was not statistically significant. Rates of cigarette and alcohol use were slightly lower in the second cohort than in the first cohort. CONCLUSIONS: This exploratory study found that marijuana use was more prevalent among teens shortly after the transition from medical marijuana legalization only to medical and nonmedical marijuana legalization, although the difference between cohorts was not statistically significant. The findings also provided some evidence of substitution effects. The analytic technique used here may be useful for examining potential long-term effects of nonmedical marijuana laws on adolescent marijuana use and substitution or spillover effects in future studies.

Psychometric Evaluation of the Symptoms and Functioning Severity Scale (SFSS) Short Forms with Out-of-Home Care Youth.

BACKGROUND: There is a need for brief progress monitoring measures of behavioral and emotional symptoms for youth in out-of-home care. The Symptoms and Functioning Severity Scale (SFSS; Bickman et al., 2010) is one measure that has clinician and youth short forms (SFSS-SFs); however, the psychometric soundness of the SFSS-SFs with youth in out-of-home care has yet to be examined. OBJECTIVE: The objective was to determine if the psychometric characteristics of the clinician and youth SFSS-SFs are viable for use in out-of-home care programs. METHODS: The participants included 143 youth receiving residential treatment and 52 direct care residential staff. The current study assessed internal consistency and alternate forms reliability for SFSS-SFs for youth in a residential care setting. Further, a binary classification test was completed to determine if the SFSS-SFs similarly classified youth as the SFSS full version for low- and elevated-severity. RESULTS: The internal consistency for the clinician and youth SFSS-SFs was adequate (α = .75 to .82) as was the parallel forms reliability (r = .85 to .97). The sensitivity (0.80 to 0.95), specificity (0.88 to 0.97), and overall accuracy (0.89 to 0.93) for differentiating low and elevated symptom severity was acceptable. CONCLUSIONS: The clinician and youth SFSS-SFs have acceptable psychometrics and may be beneficial for progress monitoring and additional research should clarify their potential for progress monitoring of youth in out-of-home programs.

Adherence and Dosage Contributions to Parenting Program Quality.

OBJECTIVE: The 3 most frequently examined elements of treatment fidelity are adherence, dosage, and quality. The relationships between these fidelity elements are complex, and additional research is needed to provide clarity. Improving clarity may be especially relevant to parenting programs, which tend to include direct explicit instruction (DEI) elements (i.e., instruction, modeling, and practice). The adherence to and dosage of these DEI elements are frequently assumed to improve program quality; however, little information is available to determine if such adherence and dosage affect program quality. This study examines whether adherence to and dosage of DEI elements predict quality ratings for a widely disseminated, manualized parenting program. METHOD: Adherence is defined as the percentage of intervention tasks completed for each DEI element. Dosage is defined as the number of minutes and seconds spent in each intervention DEI element. Treatment fidelity is assessed for 36 of 144 sessions across 10 program facilitators. A hierarchical linear regression analysis examines the contributions of adherence and dosage in the prediction of session quality ratings. RESULTS: The analysis indicates that adherence accounts for a significant proportion of the variance (26%), whereas dosage contributes a nonsignificant proportion of variance (11%). Adherence to skill practice was the strongest individual predictor (ß = .445, p < .01). CONCLUSIONS: Findings suggest that ensuring a high degree of adherence can contribute to quality program delivery. However, more exploration is needed to better understand the ways in which adherence and dosage of DEI elements affect program quality.

Validation of the symptoms and functioning severity scale in residential group care.

Tests that measure the emotional and behavioral problems of children and youth are typically not normed and standardized on youth diagnosed with disruptive behavior, particularly those youth in residential care. Yet professional standards mandate that before instruments are used with a specific population the psychometric properties need to be studied and re-established: specifically, psychometric properties, including validity, need to be evaluated (AERA, APA, and NCME, The standards for educational and psychological testing. AERA, Washington, DC, 1999). The purpose of the present study was to assess the validity characteristics of the Symptoms and Functioning Severity Scale (SFSS; Bickman et al., Manual of the Peabody Treatment Progress Battery, Vanderbilt University, Nashville, TN, 2010), a widely used test developed for use in outpatient clinics, with youth in a residential care program. The convergent validity of the SFSS was established with the large correlations (0.78-0.86) with the CBCL. Several binary classification analyses including specificity, area under the receiver operating characteristic curve, positive and negative likelihood ratios, and the Youden Index supported the validity of the SFSS. However, the sensitivity index was somewhat low indicating the test may produce a high level of false negatives. Limitations, future research and implications are discussed.

Task-specific modulation of adult humans' tool preferences: number of choices and size of the problem.

In two experiments, we examined the effect of modifications to the features of a stick-and-tube problem on the stick lengths that adult humans used to solve the problem. In Experiment 1, we examined whether people's tool preferences for retrieving an out-of-reach object in a tube might more closely resemble those reported with laboratory crows if people could modify a single stick to an ideal length to solve the problem. Contrary to when adult humans have selected a tool from a set of ten sticks, asking people to modify a single stick to retrieve an object did not generally result in a stick whose length was related to the object's distance. Consistent with the prior research, though, the working length of the stick was related to the object's distance. In Experiment 2, we examined the effect of increasing the scale of the stick-and-tube problem on people's tool preferences. Increasing the scale of the task influenced people to select relatively shorter tools than had selected in previous studies. Although the causal structures of the tasks used in the two experiments were identical, their results were not. This underscores the necessity of studying physical cognition in relation to a particular causal structure by using a variety of tasks and methods.