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Abstract Background Suicide is a leading cause of death in the United States with rates increasing over the past two decades. The rate of suicide is higher in rural areas, but a greater number of people in urban areas die by suicide; understanding risk factors for suicide in this context is critically important to public health. Additionally, while many studies have focused on individual-level risk factors, few studies have identified social or structural features associated with suicide or firearm suicide, especially among young people. Methods Study outcomes included total firearm suicide, total youth (age 10–29) firearm suicide, total suicide, and total youth suicide in Detroit, Michigan from 2012 through 2019. The predictors in this study included 58 census-tract level variables characterizing the physical features, residential stability, socioeconomic status, and demographics of neighborhoods in Detroit over the study period. We used random forest, extreme gradient boosting (XGBoost), and generalized linear mixed models to predict the four outcomes. Results We found that the tract-level variables used in all three modeling approaches performed poorly at predicting the suicide outcomes, with area under the curve values at times exceeding 0.60 but with extremely low sensitivity (ranging from 0.05 to 0.45). However, the percentage of parcels sold in arms-length transfers in the previous 5 years, the count of vacant lots per square mile, and the percentage of children aged three and older who were enrolled in preschool each demonstrated associations with at least two of the outcomes studied. Conclusions Our findings suggest place-based factors at the tract level do not provide meaningful insight into the risk of suicide or firearm suicide among youth or the general population in Detroit, Michigan. Future practice and study should consider focusing on both larger and smaller areas, including city and individual-level factors. For example, studies might benefit from the use of both neighborhood and individual-level measures and their interactions to improve our understanding of place-based risk factors and suicide risk.

ABSTRACTDesmosomes are intercellular junctions that regulate mechanical integrity in epithelia and cardiac muscle. Dynamic desmosome remodeling is essential for wound healing and development, yet the mechanisms governing junction assembly remain elusive. While we and others have shown that cadherin ectodomains are highly organized, how this ordered architecture emerges during assembly is unknown. Using fluorescence polarization microscopy, we show that desmoglein 2 (Dsg2) ectodomain order gradually increases during 8 h of assembly, coinciding with increasing adhesive strength. In a scratch wound assay, we observed a similar increase in order in desmosomes assembling at the leading edge of migratory cells. Together, our findings indicate that cadherin organization is a hallmark of desmosome maturity and may play a role in conferring adhesive strength.

Abstract Background The SARS-CoV-2 virus activates maternal and placental immune responses. Such activation in the setting of other infections during pregnancy is known to impact fetal brain development. The effects of maternal immune activation on neurodevelopment are mediated at least in part by fetal brain microglia. However, microglia are inaccessible for direct analysis, and there are no validated non-invasive surrogate models to evaluate in utero microglial priming and function. We have previously demonstrated shared transcriptional programs between microglia and Hofbauer cells (HBCs, or fetal placental macrophages) in mouse models. Methods and results We assessed the impact of maternal SARS-CoV-2 on HBCs isolated from 24 term placentas (N = 10 SARS-CoV-2 positive cases, 14 negative controls). Using single-cell RNA-sequencing, we demonstrated that HBC subpopulations exhibit distinct cellular programs, with specific subpopulations differentially impacted by SARS-CoV-2. Assessment of differentially expressed genes implied impaired phagocytosis, a key function of both HBCs and microglia, in some subclusters. Leveraging previously validated models of microglial synaptic pruning, we showed that HBCs isolated from placentas of SARS-CoV-2 positive pregnancies can be transdifferentiated into microglia-like cells (HBC-iMGs), with impaired synaptic pruning behavior compared to HBC models from negative controls. Conclusion These findings suggest that HBCs isolated at birth can be used to create personalized cellular models of offspring microglial programming.

Abstract Background Telemedicine use increased with the Covid-19 pandemic. The impact of telemedicine on resource use in pulmonary clinics is unknown. Methods This retrospective cohort study identified adults with pulmonary clinic visits at the University of Miami Hospital and Clinics (January 2018-December 2021). The primary exposure was telemedicine versus in-person visits. Standard statistics were used to describe the cohort and compare patients stratified by visit type. Multivariable logistic regression models evaluated the association of telemedicine with resource use (primarily, computed tomography [CT] orders placed within 7 days of visit). Results 21,744 clinic visits were included: 5,480 (25.2%) telemedicine and 16,264 (74.8%) in-person. In both, the majority were

Abstract: Many studies of community assembly focus on a single ontogenetic stage (typically adults) when trying to infer assembly processes from patterns of biodiversity. This focus ignores the finding that assembly mechanisms may strongly differ between life‐stages, and the role of ontogenetic dependency: the mechanisms by which one life stage directly affects the composition of another life stage. Within a 4‐ha forest dynamics plot in California USA, we explored how the relative importance of multiple assembly processes shifts across life stages and assessed ontogenetic dependency of seedlings on adults in woody plant communities. To assess variation in assembly processes across life stages, we examined how β‐diversity of adult and seedling communities were each influenced by space and 13 environmental variables (soils, topography) using distance‐based redundancy analysis and variation partitioning. We then assessed the ontogenetic dependency of seedlings on adults by including adult composition as a predictor in the seedling community variation partitioning. We found differences between adult and seedling composition. For the adults, we found 18 species including pines, oaks and manzanitas characteristic of this mid‐elevation forest. For seedlings, we found 11 species, and that oaks made up 75% of all seedlings while only making up 45% of all adults. Adult β‐diversity was primarily explained by space (44.0%) with environment only explaining 18.6% and 37.4% unexplained. In contrast, most of the explained variation in seedling β‐diversity was due to ontogenetic dependency alone (13.6% explained by adult composition) with 1.6% explained by space and the environment jointly, and 62.8% unexplained. Synthesis: Here, we describe a conceptual framework for integrating ontogeny more explicitly into community assembly research and demonstrate how different assembly processes structured adult and seedling β‐diversity in a temperate dry forest. While adult β‐diversity was largely driven by spatial processes, seedling β‐diversity was largely unexplained, with ontogenetic dependency comprising most of the explained variation. These patterns suggest that future assembly research should consider how assembly processes and their underlying mechanisms may shift with ontogeny, and that interactions between ontogenetic stages (ontogenetic dependency) are critical to consider when assessing variation in assembly processes.

Purpose: The present study explored experiences of former markers of undergraduate assignments and examinations at the University of South Africa (Unisa). Methodology: Qualitative method of research was used to gather data. Colaizzi's method (1978) was used to analyze and interpret data. The article's frame of reference was informed by Mezirow's transformative learning theory which is aligned to critical theory (Mezirow 2009). Findings: Findings were based on the following: Demographic information, markers' experiences in marking assignments and exam books, content knowledge, markers' meetings, duration of marking assignments and examination books as well as students support, and suggestions are the themes that emerged from the data that was gathered. Originality: It is recommended that the university must develop a policy for external markers for marking assignments and examinations of undergraduate program. All E-tutors must be trained to support students after the official closure of registration and before examinations are set. All markers must be trained -- through a markers' guide -- to mark assignments and examination books.

Most essential cellular functions are performed by proteins assembled into larger complexes. Fluorescence Polarization Microscopy (FPM) is a powerful technique that goes beyond traditional imaging methods by allowing researchers to measure not only the localization of proteins within cells, but also their orientation or alignment within complexes or cellular structures. FPM can be easily integrated into standard widefield microscopes with the addition of a polarization modulator. However, the extensive image processing and analysis required to interpret the data have limited its widespread adoption. To overcome these challenges and enhance accessibility, we introduce OOPS (Object-Oriented Polarization Software), a MATLAB package for object-based analysis of FPM data. By combining flexible image segmentation and novel object-based analyses with a high-throughput FPM processing pipeline, OOPS empowers researchers to simultaneously study molecular order and orientation in individual biological structures; conduct population assessments based on morphological features, intensity statistics, and FPM measurements; and create publication-quality visualizations, all within a user-friendly graphical interface. Here, we demonstrate the power and versatility of our approach by applying OOPS to punctate and filamentous structures.

Abstract In this work, we describe a novel ruthenium-xanthoxylin complex, [Ru(phen)2(xant)](PF6) (RXC), that can eliminate colorectal cancer (CRC) stem cells by targeting the chaperone Hsp90. RXC exhibits potent cytotoxicity in cancer cell lines and primary cancer cells, causing apoptosis in HCT116 CRC cells, as observed by cell morphology, YO-PRO-1/PI staining, internucleosomal DNA fragmentation, mitochondrial depolarization, and PARP cleavage (Asp214). Additionally, RXC can downregulate the HSP90AA1 and HSP90B1 genes and the expression of HSP90 protein, as well as the expression levels of its downstream/client elements Akt1, Akt (pS473), mTOR (pS2448), 4EBP1 (pT36/pT45), GSK-3β (pS9), and NF-κB p65 (pS529), implying that these molecular chaperones can be molecular targets for RXC. Moreover, this compound inhibited clonogenic survival, the percentage of the CRC stem cell subpopulation, and colonosphere formation, indicating that RXC can eliminate CRC stem cells. RXC reduced cell migration and invasion, decreased vimentin and increased E-cadherin expression, and induced an autophagic process that appeared to be cytoprotective, as autophagy inhibitors enhanced RXC-induced cell death. In vivo studies showed that RXC inhibits tumor progression and experimental metastasis in mice with CRC HCT116 cell xenografts. Taken together, these results highlight the potential of the ruthenium complex RXC in CRC therapy with the ability to eliminate CRC stem cells by targeting the chaperone Hsp90.

Abstract Background Prohibiting the purchase and possession of firearms by those at risk of violence is an established approach to preventing firearm violence. Prior studies of legal purchasers have focused on convictions for specific crimes, such as violent misdemeanors and driving under the influence (DUI). We broaden that line of inquiry by investigating and comparing the associations between prior arrests for most categories of crime and subsequent arrest for violent offenses among legal handgun purchasers in California. Methods In this longitudinal cohort study of 79,678 legal handgun purchasers in California in 2001, we group arrest charges prior to their first purchases in 2001 according to categories defined by the Uniform Crime Report (UCR) Handbook. We use a gradient boosting machine to identify categories of offenses that are most important for predicting arrest for violent crime following firearm purchase. For each category identified, we then estimate the difference in risk of subsequent arrest for a violent offense using survival regression models. Results We identified eight crime categories with high predictive importance: simple assaults, aggravated assaults, vehicle violations, weapon, other crimes, theft, drug abuse, and DUI. Compared to purchasers with no prior arrests, those with a prior arrest for any one of the eight important categories and no other categories were found to be at increased risk of arrest for a Crime Index-listed violent crime (murder, rape, robbery, aggravated assault), with the greatest estimated risk corresponding to the simple assault UCR category (adjusted hazard ratio 4.0; 95% CI 2.8–5.9). Simple assault was also associated with the greatest risk for subsequent arrest for firearm violence (adjusted hazard ratio 4.6; 95% CI 2.4–9.0) and any violent offense (adjusted hazard ratio 3.7; 95% CI 2.7–5.0). Conclusion The findings of this study suggest that prior arrests for a broad array of crimes, both violent and non-violent, are associated with risk of subsequent violent crimes, including Crime Index-listed violent crimes and firearm violence, among legal purchasers of firearms. Current policies aimed at restricting access to firearms for individuals at increased risk of violence should be re-examined considering these findings.

The purpose of this study was to compare the 5E method of inquiry-based instruction (IBI) and the four-stage model of direct instruction (DI) on students' content knowledge achievement. The population for this study was all secondary high school students enrolled in the CASE® Natural Resources and Ecology course and whose teachers completed the CASE® Institute for Natural Resources and Ecology certification between the years 2013 and 2017. This study was quasi-experimental and used a nonequivalent control group, pretest-posttest design. A convenient sample of 13 teachers and 222 students was collected. Each teacher was randomly assigned to deliver a set of 16 lesson plans that utilized either the IBI or DI approach. Lesson plans were grouped into four modules, each lasting approximately two weeks. Prior to the delivery of each module, teachers administered content knowledge pretests. Posttests were administered at the completion of each 2-week module. Students in both groups demonstrated significant gains in content knowledge achievement. ANCOVA statistical procedures were used to compare student achievement for both instructional methods. Results of the ANCOVA indicated that the 5E method of IBI and the four-stage model of DI are equally effective on students' content knowledge achievement.

IntroductionUnderstanding the pharmacokinetics and pharmacodynamics of fentanyl in horses is crucial for optimizing pain management strategies in veterinary medicine.MethodsSix adult horses were enrolled in a randomized crossover design. Treatments included: placebo, two 100 mcg/h patches (LDF), four 100 mcg/h patches (MDF), and six 100 mcg/h patches (HDF). Patches were in place for 72 h. Blood was obtained for fentanyl plasma concentration determination, thermal threshold, mechanical threshold, heart rate, respiratory rate, and rectal temperature were obtained prior patch placement and at multiple time points following patch placement for the following 96 h. Fentanyl plasma concentration was determined using LC-MS/MS. Data were analyzed using a generalized mixed effects model.ResultsMean (range) maximum plasma concentration (Cmax), time to Cmax, and area under the curve extrapolated to infinity were 1.39 (0.82–1.82), 2.64 (1.21–4.42), 4.11 (2.78–7.12) ng/ml, 12.7 (8.0–16.0), 12.7 (8.0–16.0), 12 (8.0–16.0) h, 42.37 (27.59–55.56), 77.24 (45.62–115.06), 120.34 (100.66–150.55) h ng/ml for LDF, MDF, and HDF, respectively. There was no significant effect of treatment or time on thermal threshold, mechanical threshold, respiratory rate, or temperature (p > 0.063). There was no significant effect of treatment on heart rate (p = 0.364). There was a significant effect of time (p = 0.003) on heart rate with overall heart rates being less than baseline at 64 h.ConclusionsFentanyl administered via transdermal patch is well absorbed and well tolerated but does not result in an anti-nociceptive effect as measured by thermal and mechanical threshold at the doses studied.

Recent research suggests that bilinguals might exhibit advantages in several areas of executive function, including working memory, inhibitory control, and attentional control. However, few studies have examined potential bilingual advantages within lower socioeconomic status (SES) populations. Here we addressed this gap in the literature by investigating whether low-SES Spanish–English bilingual preschoolers exhibited advantages in executive function relative to two monolingual control groups (English, Spanish). Across three experiments, bilingual children exhibited superior performance on two different measures of visual–spatial memory, as well as measures of inhibitory and attentional control. These results suggest that bilinguals exhibit broad advantages in executive function during the preschool years, and these advantages are evident within a disadvantaged, low-SES population.

Processes driving nutrient retention in stormwater green infrastructure (SGI) are not well quantified in water-limited biomes. We examined the role of plant diversity and physiochemistry as drivers of microbial community physiology and soil N dynamics post precipitation pulses in a semi-arid region experiencing drought. We conducted our study in bioswales receiving experimental water additions and a montane meadow intercepting natural rainfall. Pulses of water generally elevated soil moisture and pH, stimulated ecoenzyme activity (EEA), and increased the concentration of organic matter, proteins, and N pools in both bioswale and meadow soils. Microbial community growth was static, and N assimilation into biomass was limited across pulse events. Unvegetated plots had greater soil moisture than vegetated plots at the bioswale site, yet we detected no clear effect of plant diversity on microbial C:N ratios, EEAs, organic matter content, and N pools. Differences in soil N concentrations in bioswales and the meadow were most directly correlated to changes in organic matter content mediated by ecoenzyme expression and the balance of C, N, and P resources available to microbial communities. Our results add to growing evidence that SGI ecological function is largely comparable to neighboring natural vegetated systems, particularly when soil media and water availability are similar.

We report that the neurotrophin receptor p75 contributes to sensory neuron survival through the regulation of cholesterol metabolism in Schwann cells. Selective deletion of p75 in mouse Schwann cells of either sex resulted in a 30% loss of dorsal root ganglia (DRG) neurons and diminished thermal sensitivity. P75 regulates Schwann cell cholesterol biosynthesis in response to BDNF, forming a co-receptor complex with ErbB2 and activating ErbB2-mediated stimulation of sterol regulatory element binding protein 2 (SREBP2), a master regulator of cholesterol synthesis. Schwann cells lacking p75 exhibited decreased activation of SREBP2 and a reduction in 7-dehydrocholesterol (7-DHC) reductase (DHCR7) expression, resulting in accumulation of the neurotoxic intermediate, 7-dehyrocholesterol in the sciatic nerve. Restoration of DHCR7 in p75 null Schwann cells in mice significantly attenuated DRG neuron loss. Together, these results reveal a mechanism by which the disruption of lipid metabolism in glial cells negatively influences sensory neuron survival, which has implications for a wide range of peripheral neuropathies.SIGNIFICANCE STATEMENT Although expressed in Schwann cells, the role of p75 in myelination has remained unresolved in part because of its dual expression in sensory neurons that Schwann cells myelinate. When p75 was deleted selectively among Schwann cells, myelination was minimally affected, while sensory neuron survival was reduced by 30%. The phenotype is mainly due to dysregulation of cholesterol biosynthesis in p75-deficient Schwann cells, leading to an accumulation of neurotoxic cholesterol precursor, 7-dehydrocholesterol (7-DHC). Mechanism-wise, we discovered that in response to BDNF, p75 recruits and activates ErbB2 independently of ErbB3, thereby stimulating the master regulator, sterol regulatory element binding protein 2 (SREBP2). These results together highlight a novel role of p75 in Schwann cells in regulating DRG neuron survival by orchestrating proper cholesterol metabolism.

Climate change and evolution are topics at the forefront of political discussions, debates, and the public sphere. Regardless of evidence on both topics, the public as a whole still believes they are under debate. It is imperative that the public have access to correct and easy-to-digest information on these topics to make informed environmental and ecological decisions. To date, scientifically accurate digital platforms aimed at informing the public on these topics are overly complex and jargon-ridden. Time Scavengers (www.timescavengers.blog) was created to address these issues and is maintained by a group of academics, graduate students, avocational scientists, and educators. The site includes many informational pages about geology, climate change, and evolution, all written for the public with useful descriptions and figures. To make the process of science more transparent, the site includes blogs to provide insight into data collection and interpretation, field work, and public outreach. The site also includes additional pages with links to relevant content and activities appropriate for K-12 classrooms. The overarching goals of the site are to bridge the gap between scientists and the public through engaging, informational pages and personal experiences and to increase science literacy through easy-to-digest content.

About 77% of the 770 million people living without access to electricity today reside in sub-Saharan Africa (SSA). Increasing access to energy in the region could raise prospects for the [...]

Abstract Aging alters the amplitude and phase of centrally regulated circadian rhythms. Here we evaluate whether peripheral circadian rhythmicity in the plasma lipidome is altered by aging through retrospective lipidomics analysis on plasma samples collected in 24 healthy individuals (9 females; mean ± SD age: 40.9 ± 18.2 years) including 12 younger (4 females, 23.5 ± 3.9 years) and 12 middle-aged older, (5 females, 58.3 ± 4.2 years) individuals every 3 h throughout a 27-h constant routine (CR) protocol, which allows separating evoked changes from endogenously generated oscillations in physiology. Cosinor regression shows circadian rhythmicity in 25% of lipids in both groups. On average, the older group has a ~14% lower amplitude and a ~2.1 h earlier acrophase of the lipid circadian rhythms (both, p ≤ 0.001). Additionally, more rhythmic circadian lipids have a significant linear component in addition to the sinusoidal across the 27-h CR in the older group (44/56) compared to the younger group (18/58, p

Abstract Background Suicide is a pressing public health problem, and firearm owners are at especially elevated risk. Certain health conditions are markers of suicide risk, but more research is needed on clinical risk markers for suicide among firearm owners specifically. Our goal was to examine associations of emergency department and inpatient hospital visits for behavioral and physical health conditions with firearm suicide among handgun purchasers. Methods This was a case–control study of 5415 legal handgun purchasers in California who died between January 1, 2008, and December 31, 2013. Cases were firearm suicide decedents; controls were motor vehicle crash decedents. Exposures were emergency department and hospital visits for six categories of health diagnoses in the 3 years prior to death. To account for selection bias due to deceased controls, we used probabilistic quantitative bias analysis to generate bias-adjusted estimates. Results There were 3862 firearm suicide decedents and 1553 motor vehicle crash decedents. In multivariable models, suicidal ideation/attempt (OR 4.92; 95% CI 3.27–7.40), mental illness (OR 1.97; 95% CI 1.60–2.43), drug use disorder (OR 1.40; 95% CI 1.05–1.88), pain (OR 1.34; 95% CI 1.07–1.69), and alcohol use disorder (OR 1.29; 95% CI 1.01–1.65) were associated with higher odds of firearm suicide. When adjusting for all conditions simultaneously, only the associations for suicidal ideation/attempt and mental illness remained significant. Quantitative bias analysis indicated that observed associations were generally biased downward. For example, the bias-adjusted OR for suicidal ideation/attempt was 8.39 (95% simulation interval 5.46–13.04), almost twice that of the observed OR. Conclusions Diagnoses for behavioral health conditions were markers for firearm suicide risk among handgun purchasers, even for conservative estimates that did not adjust for selection bias. Encounters with the healthcare system may provide opportunities to identify firearm owners at high risk of suicide.

Background: Anti-melanoma differentiation-associated gene 5-positive (anti-MDA5) dermatomyositis (DM) is a rare autoimmune disease associated with rapidly-progressive interstitial lung disease (RP-ILD.) The reported morbidity and 6-month mortality remains high from 33 to 66 % with RP-ILD most often developing within three months of diagnosis. Most cases require aggressive immunosuppression with combination therapy. Asymptomatic or slowly progressive cases of anti-MDA5 ILD are not well described in the literature. We report three cases of Latino patients with asymptomatic or slowly progressive anti-MDA5 ILD.Case descriptions: Case 1: A 54-year-old woman from Honduras with known diagnosis of anti-MDA5 dermatomyositis presented for ILD. She denied respiratory symptoms. Computed tomography (CT) chest showed multifocal patchy areas of scattered groundglass opacities throughout all lobes of the lungs, predominately in a subpleural distribution within the lower lobes. Pulmonary function testing (PFTs) showed mild-to-moderate restriction. She was treated with mycophenolate mofetil monotherapy for her skin manifestations. At 18 months follow-up, she denied respiratory symptoms, and PFTs were normal. Case 2: An 80-year-old man from Cuba was seen in pulmonary clinic to establish care. He was diagnosed with pulmonary fibrosis 11 years earlier with positive anti-MDA5. He denied respiratory symptoms. PFTs showed moderate obstruction and mild to moderate restriction. CT chest showed reduced lung volumes and findings compatible with usual interstitial pneumonia. He was started on nintedanib. Fifteen months following the initial visit, his PFTs remained stable. Follow-up CT chest showed stable pulmonary fibrosis. At all subsequent visits, he reported mild to moderate, slowly progressive dyspnea on exertion and was maintained on nintedanib. Thirteen years after his initial ILD diagnosis, he was diagnosed with pancreatic adenocarcinoma. Case 3: A 70-year-old woman from Peru presented to pulmonary clinic with cough for two months. She also reported pain in several metacarpophalangeal joints. She denied dyspnea. Rheumatologic serologies revealed positive anti-MDA5. PFTs were normal. Her cough was treated with cough suppressants and resolved. At a subsequent visit 8 months after presentation, she denied respiratory symptoms, and her joint pain remained mild. Given her lack of respiratory symptoms and normal PFTs, she was not initiated on ILD-specific treatment. Conclusions: While anti-MDA5 ILD is certainly associated with RP-ILD, clinicians should maintain awareness that there may be cases of asymptomatic or slowly progressive ILD as well.

Antimicrobial resistance is a global threat to human and animal health, with the misuse and overuse of antimicrobials suggested as the main drivers of resistance. Antimicrobial therapy can alter the bacterial community composition and the faecal resistome in cattle. Little is known about the impact of systemic antimicrobial therapy on the faecal microbiome in dairy cows in the presence of disease. Therefore, this study aimed to assess the impact of systemic antimicrobial therapy on the faecal microbiome in dairy cows in the pastoral farm environment, by analysing faecal samples from cattle impacted by several different clinically-defined conditions and corresponding antimicrobial treatments. Analysis at the individual animal level showed a decrease in bacterial diversity and richness during antimicrobial treatment but, in many cases, the microbiome diversity recovered post-treatment when the cow re-entered the milking herd. Perturbations in the microbiome composition and the ability of the microbiome to recover were specific at the individual animal level, highlighting that the animal is the main driver of variation. Other factors such as disease severity, the type and duration of antimicrobial treatment and changes in environmental factors may also impact the bovine faecal microbiome. AmpC-producing Escherichia coli were isolated from faeces collected during and post-treatment with ceftiofur from one cow while no third-generation cephalosporin resistant E. coli were isolated from the untreated cow samples. This isolation of genetically similar plasmid-mediated AmpC-producing E. coli has implications for the development and dissemination of antibiotic resistant bacteria and supports the reduction in the use of critically important antimicrobials.

Although most U. S. children can accurately count sets by 4 years of age, many fail to understand the structural analogy between counting and number - that adding 1 to a set corresponds to counting up 1 word in the count list. While children are theorized to establish this Structure Mapping coincident with learning how counting is used to generate sets, they initially have an item-based understanding of this relationship, and can infer that, e.g, adding 1 to "five" is "six", while failing to infer that, e.g., adding 1 to "twenty-five" is "twenty-six" despite being able to recite these numbers when counting aloud. The item-specific nature of children's successes in reasoning about the relationship between changes in cardinality and the count list raises the possibility that such a Structure Mapping emerges later in development, and that this ability does not initially depend on learning to count. We test this hypothesis in two experiments and find evidence that children can perform item-based addition operations before they become competent counters. Even after children learn to count, we find that their ability to perform addition operations remains item-based and restricted to very small numbers, rather than drawing on generalized knowledge of how the count list represents number. We discuss how these early item-based associations between number words and sets might play a role in constructing a generalized Structure Mapping between counting and quantity.