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Objectives: Metrics and instruments can provide guidance for clinical researchers to assess their potential research projects at an early stage before significant investment. Furthermore, metrics can also provide structured criteria for peer reviewers to assess others' clinical research manuscripts or grant proposals. This study aimed to develop, test, validate, and use evaluation metrics and instruments to accurately, consistently, systematically, and conveniently assess the quality of scientific hypotheses for clinical research projects., Materials and Methods: Metrics development went through iterative stages, including literature review, metrics and instrument development, internal and external testing and validation, and continuous revisions in each stage based on feedback. Furthermore, two experiments were conducted to determine brief and comprehensive versions of the instrument., Results: The brief version of the instrument contained three dimensions: validity, significance, and feasibility. The comprehensive version of metrics included novelty, clinical relevance, potential benefits and risks, ethicality, testability, clarity, interestingness, and the three dimensions of the brief version. Each evaluation dimension included 2 to 5 subitems to evaluate the specific aspects of each dimension. For example, validity included clinical validity and scientific validity. The brief and comprehensive versions of the instruments included 12 and 39 subitems, respectively. Each subitem used a 5-point Likert scale., Conclusion: The validated brief and comprehensive versions of metrics can provide standardized, consistent, systematic, and generic measurements for clinical research hypotheses, allow clinical researchers to prioritize their research ideas systematically, objectively, and consistently, and can be used as a tool for quality assessment during the peer review process., Competing Interests: Declarations. Ethics approval and consent to participate: This study was approved by the Ohio University Institutional Review Board (18-X-192) and Clemson University Institutional Review Board (IRB2020-056). All participants received IRB-approved consent forms before the study sessions, and informed consent was obtained verbally from all participants before conducting each study session. We confirm that all methods were carried out in accordance with relevant guidelines and regulations with corresponding citations. Consent for publication: Not applicable. Competing interests: The authors declare no competing interests., (© 2025. The Author(s).)

Objectives: We invited inexperienced clinical researchers to analyze coded health datasets and develop hypotheses. We recorded and analyzed their hypothesis generation process. All the hypotheses generated in the process were rated by the same group of seven experts by using the same metrics. This case study examines the higher quality (i.e., higher ratings) and lower quality of hypotheses and participants who generated them. We characterized the contextual factors associated with the quality of hypotheses., Methods: All participants (i.e., clinical researchers) completed a 2-hour study session to analyze data and generate scientific hypotheses using the think-aloud method. Participants' screen activity and audio were recorded and transcribed. These transcriptions were used to measure the time used to generate each hypothesis and to code cognitive events (i.e., cognitive activities used when generating hypotheses, for example, "Seeking for Connection" describes an attempt to draw connections between data points). The hypothesis ratings by the expert panel were used as the quality of the hypotheses during the analysis. We analyzed the factors associated with (1) the five highest and (2) five lowest rated hypotheses and (3) the participants who generated them, including the number of hypotheses per participant, the validity of those hypotheses, the number of cognitive events used for each hypothesis, as well as the participant's research experience and basic demographics., Results: Participants who generated the five highest-rated hypotheses used similar lengths of time (difference 3:03), whereas those who generated the five lowest-rated hypotheses used more varying lengths of time (difference 7:13). Participants who generated the five highest-rated hypotheses also utilized slightly fewer cognitive events on average compared to the five lowest-rated hypotheses (4 per hypothesis vs. 4.8 per hypothesis). When we examine the participants (who generated the five highest and five lowest hypotheses) and their total hypotheses generated during the 2-hour study sessions, the participants with the five highest-rated hypotheses again had a shorter range of time per hypothesis on average (0:03:34 vs. 0:07:17). They (with the five highest ratings) used fewer cognitive events per hypothesis (3.498 vs. 4.626). They (with the five highest ratings) also had a higher percentage of valid rate (75.51% vs. 63.63%) and generally had more experience with clinical research., Conclusion: The quality of the hypotheses was shown to be associated with the time taken to generate them, where too long or too short time to generate hypotheses appears to be negatively associated with the hypotheses' quality ratings. Also, having more experience seems to positively correlate with higher ratings of hypotheses and higher valid rates. Validity is a quality dimension used by the expert panel during rating. However, we acknowledge that our results are anecdotal. The effect may not be simply linear, and future research is necessary. These results underscore the multi-factor nature of hypothesis generation., Competing Interests: Competing interests: none.

Encouraging diversity in biomedical fields is especially important and begins at the undergraduate level. Culturally competent mentorship and high impact practices, like involvement in research, play important roles in fostering success among undergraduates from historically underrepresented groups. The current study followed 20 biomedical faculty as they completed two semester-long trainings, one in mentoring and one in course based undergraduate research (CUREs) as part of the NIH Diversity Program Consortium Dissemination and Translation Awards initiative. Comparisons of pre- and post-training survey data showed increased self-efficacy for mentoring biomedical research trainees and for mentoring diverse groups of biomedical trainees. These results suggest that focused, formal faculty training can be effective for improving mentoring, and consequently success of biomedical students.

Hypothesis generation is an early and critical step in any hypothesis-driven clinical research project. Because it is not yet a well-understood cognitive process, the need to improve the process goes unrecognized. Without an impactful hypothesis, the significance of any research project can be questionable, regardless of the rigor or diligence applied in other steps of the study, e.g., study design, data collection, and result analysis. In this perspective article, the authors provide a literature review on the following topics first: scientific thinking, reasoning, medical reasoning, literature-based discovery, and a field study to explore scientific thinking and discovery. Over the years, scientific thinking has shown excellent progress in cognitive science and its applied areas: education, medicine, and biomedical research. However, a review of the literature reveals the lack of original studies on hypothesis generation in clinical research. The authors then summarize their first human participant study exploring data-driven hypothesis generation by clinical researchers in a simulated setting. The results indicate that a secondary data analytical tool, VIADS-a visual interactive analytic tool for filtering, summarizing, and visualizing large health data sets coded with hierarchical terminologies, can shorten the time participants need, on average, to generate a hypothesis and also requires fewer cognitive events to generate each hypothesis. As a counterpoint, this exploration also indicates that the quality ratings of the hypotheses thus generated carry significantly lower ratings for feasibility when applying VIADS. Despite its small scale, the study confirmed the feasibility of conducting a human participant study directly to explore the hypothesis generation process in clinical research. This study provides supporting evidence to conduct a larger-scale study with a specifically designed tool to facilitate the hypothesis-generation process among inexperienced clinical researchers. A larger study could provide generalizable evidence, which in turn can potentially improve clinical research productivity and overall clinical research enterprise.

Objectives: To compare how clinical researchers generate data-driven hypotheses with a visual interactive analytic tool (VIADS, a visual interactive analysis tool for filtering and summarizing large datasets coded with hierarchical terminologies) or other tools., Methods: We recruited clinical researchers and separated them into "experienced" and "inexperienced" groups. Participants were randomly assigned to a VIADS or control group within the groups. Each participant conducted a remote 2-hour study session for hypothesis generation with the same study facilitator on the same datasets by following a think-aloud protocol. Screen activities and audio were recorded, transcribed, coded, and analyzed. Hypotheses were evaluated by seven experts on their validity, significance, and feasibility. We conducted multilevel random effect modeling for statistical tests., Results: Eighteen participants generated 227 hypotheses, of which 147 (65%) were valid. The VIADS and control groups generated a similar number of hypotheses. The VIADS group took a significantly shorter time to generate one hypothesis (e.g., among inexperienced clinical researchers, 258 s versus 379 s, p = 0.046, power = 0.437, ICC = 0.15). The VIADS group received significantly lower ratings than the control group on feasibility and the combination rating of validity, significance, and feasibility., Conclusion: The role of VIADS in hypothesis generation seems inconclusive. The VIADS group took a significantly shorter time to generate each hypothesis. However, the combined validity, significance, and feasibility ratings of their hypotheses were significantly lower. Further characterization of hypotheses, including specifics on how they might be improved, could guide future tool development., Competing Interests: The authors have no competing interests to declare., (© The Author(s) 2024.)

Objectives: This study aims to identify the cognitive events related to information use (e.g., "Analyze data", "Seek connection") during hypothesis generation among clinical researchers. Specifically, we describe hypothesis generation using cognitive event counts and compare them between groups., Methods: The participants used the same datasets, followed the same scripts, used VIADS (a visual interactive analysis tool for filtering and summarizing large data sets coded with hierarchical terminologies) or other analytical tools (as control) to analyze the datasets, and came up with hypotheses while following the think-aloud protocol. Their screen activities and audio were recorded and then transcribed and coded for cognitive events., Results: The VIADS group exhibited the lowest mean number of cognitive events per hypothesis and the smallest standard deviation. The experienced clinical researchers had approximately 10% more valid hypotheses than the inexperienced group. The VIADS users among the inexperienced clinical researchers exhibit a similar trend as the experienced clinical researchers in terms of the number of cognitive events and their respective percentages out of all the cognitive events. The highest percentages of cognitive events in hypothesis generation were "Using analysis results" (30%) and "Seeking connections" (23%)., Conclusion: VIADS helped inexperienced clinical researchers use fewer cognitive events to generate hypotheses than the control group. This suggests that VIADS may guide participants to be more structured during hypothesis generation compared with the control group. The results provide evidence to explain the shorter average time needed by the VIADS group in generating each hypothesis.

Objectives: To compare how clinical researchers generate data-driven hypotheses with a visual interactive analytic tool (VIADS, a visual interactive analysis tool for filtering and summarizing large data sets coded with hierarchical terminologies) or other tools., Methods: We recruited clinical researchers and separated them into "experienced" and "inexperienced" groups. Participants were randomly assigned to a VIADS or control group within the groups. Each participant conducted a remote 2-hour study session for hypothesis generation with the same study facilitator on the same datasets by following a think-aloud protocol. Screen activities and audio were recorded, transcribed, coded, and analyzed. Hypotheses were evaluated by seven experts on their validity, significance, and feasibility. We conducted multilevel random effect modeling for statistical tests., Results: Eighteen participants generated 227 hypotheses, of which 147 (65%) were valid. The VIADS and control groups generated a similar number of hypotheses. The VIADS group took a significantly shorter time to generate one hypothesis (e.g., among inexperienced clinical researchers, 258 seconds versus 379 seconds, p = 0.046, power = 0.437, ICC = 0.15). The VIADS group received significantly lower ratings than the control group on feasibility and the combination rating of validity, significance, and feasibility., Conclusion: The role of VIADS in hypothesis generation seems inconclusive. The VIADS group took a significantly shorter time to generate each hypothesis. However, the combined validity, significance, and feasibility ratings of their hypotheses were significantly lower. Further characterization of hypotheses, including specifics on how they might be improved, could guide future tool development., Competing Interests: Competing interests disclosure statement N/A

Objectives: Metrics and instruments can provide guidance for clinical researchers to assess their potential research projects at an early stage before significant investment. Furthermore, metrics can also provide structured criteria for peer reviewers to assess others' clinical research manuscripts or grant proposals. This study aimed to develop, test, validate, and use evaluation metrics and instruments to accurately, consistently, and conveniently assess the quality of scientific hypotheses for clinical research projects., Materials and Methods: Metrics development went through iterative stages, including literature review, metrics and instrument development, internal and external testing and validation, and continuous revisions in each stage based on feedback. Furthermore, two experiments were conducted to determine brief and comprehensive versions of the instrument., Results: The brief version of the instrument contained three dimensions: validity, significance, and feasibility. The comprehensive version of metrics included novelty, clinical relevance, potential benefits and risks, ethicality, testability, clarity, interestingness, and the three dimensions of the brief version. Each evaluation dimension included 2 to 5 subitems to evaluate the specific aspects of each dimension. For example, validity included clinical validity and scientific validity. The brief and comprehensive versions of the instruments included 12 and 39 subitems, respectively. Each subitem used a 5-point Likert scale., Conclusion: The validated brief and comprehensive versions of metrics can provide standardized, consistent, and generic measurements for clinical research hypotheses, allow clinical researchers to prioritize their research ideas systematically, objectively, and consistently, and can be used as a tool for quality assessment during the peer review process., Competing Interests: Competing interests None to disclose.

Background: Visualization can be a powerful tool to comprehend data sets, especially when they can be represented via hierarchical structures. Enhanced comprehension can facilitate the development of scientific hypotheses. However, the inclusion of excessive data can make visualizations overwhelming., Objective: We developed a visual interactive analytic tool for filtering and summarizing large health data sets coded with hierarchical terminologies (VIADS). In this study, we evaluated the usability of VIADS for visualizing data sets of patient diagnoses and procedures coded in the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM)., Methods: We used mixed methods in the study. A group of 12 clinical researchers participated in the generation of data-driven hypotheses using the same data sets and time frame (a 1-hour training session and a 2-hour study session) utilizing VIADS via the think-aloud protocol. The audio and screen activities were recorded remotely. A modified version of the System Usability Scale (SUS) survey and a brief survey with open-ended questions were administered after the study to assess the usability of VIADS and verify their intense usage experience with VIADS., Results: The range of SUS scores was 37.5 to 87.5. The mean SUS score for VIADS was 71.88 (out of a possible 100, SD 14.62), and the median SUS was 75. The participants unanimously agreed that VIADS offers new perspectives on data sets (12/12, 100%), while 75% (8/12) agreed that VIADS facilitates understanding, presentation, and interpretation of underlying data sets. The comments on the utility of VIADS were positive and aligned well with the design objectives of VIADS. The answers to the open-ended questions in the modified SUS provided specific suggestions regarding potential improvements for VIADS, and the identified problems with usability were used to update the tool., Conclusions: This usability study demonstrates that VIADS is a usable tool for analyzing secondary data sets with good average usability, good SUS score, and favorable utility. Currently, VIADS accepts data sets with hierarchical codes and their corresponding frequencies. Consequently, only specific types of use cases are supported by the analytical results. Participants agreed, however, that VIADS provides new perspectives on data sets and is relatively easy to use. The VIADS functionalities most appreciated by participants were the ability to filter, summarize, compare, and visualize data., International Registered Report Identifier (irrid): RR2-10.2196/39414., (©Xia Jing, Vimla L Patel, James J Cimino, Jay H Shubrook, Yuchun Zhou, Brooke N Draghi, Mytchell A Ernst, Chang Liu, Sonsoles De Lacalle. Originally published in JMIR Human Factors (https://humanfactors.jmir.org), 27.04.2023.)

Background: Scientific hypothesis generation is a critical step in scientific research that determines the direction and impact of any investigation. Despite its vital role, we have limited knowledge of the process itself, thus hindering our ability to address some critical questions., Objective: This study aims to answer the following questions: To what extent can secondary data analytics tools facilitate the generation of scientific hypotheses during clinical research? Are the processes similar in developing clinical diagnoses during clinical practice and developing scientific hypotheses for clinical research projects? Furthermore, this study explores the process of scientific hypothesis generation in the context of clinical research. It was designed to compare the role of VIADS, a visual interactive analysis tool for filtering and summarizing large data sets coded with hierarchical terminologies, and the experience levels of study participants during the scientific hypothesis generation process., Methods: This manuscript introduces a study design. Experienced and inexperienced clinical researchers are being recruited since July 2021 to take part in this 2×2 factorial study, in which all participants use the same data sets during scientific hypothesis-generation sessions and follow predetermined scripts. The clinical researchers are separated into experienced or inexperienced groups based on predetermined criteria and are then randomly assigned into groups that use and do not use VIADS via block randomization. The study sessions, screen activities, and audio recordings of participants are captured. Participants use the think-aloud protocol during the study sessions. After each study session, every participant is given a follow-up survey, with participants using VIADS completing an additional modified System Usability Scale survey. A panel of clinical research experts will assess the scientific hypotheses generated by participants based on predeveloped metrics. All data will be anonymized, transcribed, aggregated, and analyzed., Results: Data collection for this study began in July 2021. Recruitment uses a brief online survey. The preliminary results showed that study participants can generate a few to over a dozen scientific hypotheses during a 2-hour study session, regardless of whether they used VIADS or other analytics tools. A metric to more accurately, comprehensively, and consistently assess scientific hypotheses within a clinical research context has been developed., Conclusions: The scientific hypothesis-generation process is an advanced cognitive activity and a complex process. Our results so far show that clinical researchers can quickly generate initial scientific hypotheses based on data sets and prior experience. However, refining these scientific hypotheses is a much more time-consuming activity. To uncover the fundamental mechanisms underlying the generation of scientific hypotheses, we need breakthroughs that can capture thinking processes more precisely., International Registered Report Identifier (irrid): DERR1-10.2196/39414., (©Xia Jing, Vimla L Patel, James J Cimino, Jay H Shubrook, Yuchun Zhou, Chang Liu, Sonsoles De Lacalle. Originally published in JMIR Research Protocols (https://www.researchprotocols.org), 18.07.2022.)

Mouse models are often used to validate novel interventions prior to human testing, although biological differences between mice and humans limit the translatability of outcomes. A common assumption in animal research is that maximal physical performance will be present at a young age, and that differences in task performance between young and old can be attributed to the aging process. However, this may not be true for all physical function tasks, and leaving out intermediate time points could drastically alter data interpretation. Here, we document age-related changes in forelimb and hindlimb grip strength, balance and coordination, and body composition in mice (n = 43) collected at multiple time points between 4 and 24 months of age. Maximal forelimb grip strength was recorded at 4 months of age, but maximal hindlimb grip strength was recorded at 15 months of age. Balance performance was stable from 4 to 15 months of age, declining significantly at 18 months. Both lean and fat mass peaked at 18 months before declining steadily. We conclude that the inclusion of intermediate time points is essential for the accurate evaluation of physical function status in mice, particularly in the context of translating intervention outcomes into strategies to be tested in humans., (© The Author(s) 2021. Published by Oxford University Press on behalf of The Gerontological Society of America.)

Age-related declines in muscle function result from changes in muscle structure and contractile properties, as well as from neural adaptations. Blocking myostatin to drive muscle growth is one potential therapeutic approach. While the effects of myostatin depletion on muscle characteristics are well established, we have very little understanding of its effects on the neural system. Here we assess the effects of long-term, post-developmental myostatin reduction on electrophysiological motor unit characteristics and body composition in aging mice. We used male (N = 21) and female (N = 26) mice containing a tetracycline-inducible system to delete the myostatin gene in skeletal muscle. Starting at 12 months of age, half of the mice were administered doxycycline (tetracycline) through their chow for one year. During that time we measured food intake, body composition, and hindlimb electromyographic responses. Doxycycline-induced myostatin reduction had no effect on motor unit properties for either sex, though significant age-dependent declines in motor unit number occurred in all mice. However, treatment with doxycycline induced different changes in body composition between sexes. All female mice increased in total, lean and fat mass, but doxycycline-treated female mice experienced a significantly larger increase in lean mass than controls. All male mice also increased total and lean mass, but administration of doxycycline had no effect. Additionally, doxycycline-treated male mice maintained their fat mass at baseline levels, while the control group experienced a significant increase from baseline and compared to the doxycycline treated group. Our results show that long-term administration of doxycycline results in body composition adaptations that are distinctive between male and female mice, and that the effects of myostatin reduction are most pronounced during the first three months of treatment. We also report that age-related changes in motor unit number are not offset by reduced myostatin levels, despite increased lean mass exhibited by female mice., Competing Interests: The authors have declared that no competing interests exist.

Background: Vast volumes of data, coded through hierarchical terminologies (e.g., International Classification of Diseases, Tenth Revision-Clinical Modification [ICD10-CM], Medical Subject Headings [MeSH]), are generated routinely in electronic health record systems and medical literature databases. Although graphic representations can help to augment human understanding of such data sets, a graph with hundreds or thousands of nodes challenges human comprehension. To improve comprehension, new tools are needed to extract the overviews of such data sets. We aim to develop a visual interactive analytic tool for filtering and summarizing large health data sets coded with hierarchical terminologies (VIADS) as an online, and publicly accessible tool. The ultimate goals are to filter, summarize the health data sets, extract insights, compare and highlight the differences between various health data sets by using VIADS. The results generated from VIADS can be utilized as data-driven evidence to facilitate clinicians, clinical researchers, and health care administrators to make more informed clinical, research, and administrative decisions. We utilized the following tools and the development environments to develop VIADS: Django, Python, JavaScript, Vis.js, Graph.js, JQuery, Plotly, Chart.js, Unittest, R, and MySQL., Results: VIADS was developed successfully and the beta version is accessible publicly. In this paper, we introduce the architecture design, development, and functionalities of VIADS. VIADS includes six modules: user account management module, data sets validation module, data analytic module, data visualization module, terminology module, dashboard. Currently, VIADS supports health data sets coded by ICD-9, ICD-10, and MeSH. We also present the visualization improvement provided by VIADS in regard to interactive features (e.g., zoom in and out, customization of graph layout, expanded information of nodes, 3D plots) and efficient screen space usage., Conclusions: VIADS meets the design objectives and can be used to filter, summarize, compare, highlight and visualize large health data sets that coded by hierarchical terminologies, such as ICD-9, ICD-10 and MeSH. Our further usability and utility studies will provide more details about how the end users are using VIADS to facilitate their clinical, research or health administrative decision making.

Selective serotonin reuptake inhibitor medications (SSRIs) are prescribed to up to 10% of pregnant women to treat maternal mood disorders. Exposure to these medications in-utero has raised concerns about altered neurobehavioral outcomes; most recently those related to peer-to-peer social interactions and play. While clinical data show that both perinatal SSRIs (pSSRI) and maternal stress can contribute to social behavioral changes in children, minimal animal work has investigated the effects of pSSRIs in relevant models of maternal stress or the long-term implications of these effects. Therefore the aim of this work was to investigate the long-term effects of pSSRI exposure to fluoxetine on social behaviors, the hypothalamic pituitary adrenal system (HPA) and hippocampal plasticity in adult male and female rat offspring using a model of pre-gestational maternal stress. Adult Sprague-Dawley female and male rat offspring from the following four groups were utilized: 1. Control + Vehicle, 2. Control + Fluoxetine, 3. Pre-gestational Stress + Vehicle, 4. Pre-gestational Stress + Fluoxetine (n = 8-16/female/age groups, n = 8-14/male/age groups). Main findings show pSSRIs increased social investigation in adult females and increased social play (pouncing, nape attacks) in adult males. Perinatal SSRIs also had sexually differentiated effects on hippocampal neurogenesis and GR density. Pre-gestational stress had enduring effects by decreasing social investigation and hippocampal neurogenesis in adult males. Thus pSSRIs, as well as pre-gestational maternal stress, have significant long-term effects on social neurobehavioral outcomes which differ in males and females. This suggests that it would be valuable to consider fetal-sex specific treatments for maternal mental illness., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Myostatin, a negative regulator of muscle growth, is considered a potential therapeutic agent for individuals suffering from various muscle wasting and strength declining diseases because inhibiting Mstn signaling leads to muscular hypertrophy. In this study we investigate the interaction between myostatin and the growth hormone/insulin-like growth factor-1 (GH/IGF-1) axis in muscle function and strength. To this end, we measured hind limb grip strength and myostatin levels in two mouse models of GH gene manipulation; GH receptor knockout ( GHR -/- ) mice which have reduced GH/IGF-1 action, and bovine GH transgenic (bGH) mice which have excess GH/IGF-1 action. We found that specific muscle force was significantly reduced in bGH mice, and significantly increased in GHR -/- mice, compared to their respective littermate wild type controls. The expression of the mature form of myostatin was significantly increased in bGH mice, and unchanged in GHR -/- mice. In the bGH mice, the high levels of mature myostatin were accompanied by increase body weight and lean mass, consistent with other published results indicating that the IGF-1 signaling pathway is dominant over that of Mstn. Our results also suggest that in these mouse models there is an inverse relationship between muscle strength and levels of myostatin and GH, since constitutive overexpression of GH resulted in elevated levels of mature myostatin in muscle, accompanied by a reduction in strength. By contrast, in the GHR -/- mice with reduced levels of IGF-1, mature myostatin levels were unchanged and muscle strength was increased.

Selective serotonin reuptake inhibitor medications (SSRIs) are the first lines of treatment for maternal affective disorders, and are prescribed to up to 10% of pregnant women. Concern has been raised about how perinatal exposure to these medications affect offspring neurobehavioral outcomes, particularly those related to social interactions, as recent research has reported conflicting results related to autism spectrum disorder (ASD) risk in children prenatally exposed to SSRIs. Therefore, the aim of this work was to investigate the effects of perinatal exposure to the SSRI fluoxetine on social play behaviors and the hypothalamic pituitary adrenal system, using a model of pre-gestational maternal stress. We also investigated synaptic proteins in the CA2, CA3, and dentate gyrus of the hippocampus, as well as number of immature neurons in the granule cell layer, as both measures of plasticity in the hippocampus have been linked to social behaviors. In pre-adolescent male and female Sprague-Dawley rat offspring, main findings show that perinatal fluoxetine prevents the negative effect of maternal stress on sibling play behavior. However, perinatal fluoxetine increased social aggressive play with a novel conspecific in both sexes and decreased time grooming a novel conspecific in males only. Perinatal fluoxetine also increased serum corticosteroid binding globulin levels, 5-HT levels in the hippocampus, and pre-synaptic density assessed via synaptophysin in the dentate gyrus. Social interaction was significantly correlated with changes in plasticity in the CA2 region of the hippocampus. Pre-gestational maternal stress exposure resulted in significantly decreased rates of hippocampal neurogenesis and synaptophysin density in the dentate gyrus of pre-adolescent males, but not females. Together, these results further characterize the role of perinatal SSRIs, maternal stress prior to conception, and sex/gender on developing social behaviors and related plasticity in the hippocampus of pre-adolescent offspring., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Selective serotonin reuptake inhibitor medication exposure during the perinatal period can have a long term impact in adult offspring on neuroplasticity and the serotonergic system, but the impact of these medications during early development is poorly understood. The aim of this study was to determine the effects of developmental exposure to the SSRI, fluoxetine, on the serotonergic system, dopaminergic system, and synaptophysin density in the prefrontal cortex and hippocampus, as well as number of immature neurons in the dentate gyrus, in juvenile rat offspring at weaning. To model aspects of maternal depression, prenatal restraint stress was used. Sprague-Dawley rat offspring were exposed to either prenatal stress and/or fluoxetine. Main findings show that developmental fluoxetine exposure to prenatally stressed offspring decreased 5-HT and 5-HIAA levels and altered the dopaminergic system in the hippocampus. Prenatal stress, regardless of fluoxetine, increased synaptophysin density in the PFC. This work indicates that early exposure to maternal stress and SSRI medication can alter brain monoamine levels and synaptophysin density in offspring at weaning., (© 2015 Wiley Periodicals, Inc.)

As a negative regulator of muscle size, myostatin (Mstn) impacts the force-production capabilities of skeletal muscles. In the masticatory system, measures of temporalis-stimulated bite forces in constitutive myostatin KOs suggest an absolute, but not relative, increase in jaw-muscle force. Here, we assess the phenotypic and physiologic impact of postnatal myostatin inhibition on bite mechanics using an inducible conditional KO mouse in which myostatin is inhibited with doxycycline (DOX). Given the increased control over the timing of gene inactivation in this model, it may be more clinically-relevant for developing interventions for age-associated changes in the musculoskeletal system. DOX was administered for 12 weeks starting at age 4 months, during which time food intake was monitored. Sex, age and strain-matched controls were given the same food without DOX. Bite forces were recorded just prior to euthanasia after which muscle and skeletal data were collected. Food intake did not differ between control or DOX animals within each sex. DOX males were significantly larger and had significantly larger masseters than controls, but DOX and control females did not differ. Although there was a tendency towards higher absolute bite forces in DOX animals, this was not significant, and bite forces normalized to masseter mass did not differ. Mechanical advantage for incisor biting increased in the DOX group due to longer masseter moment arms, likely due to a more anteriorly-placed masseter insertion. Despite only a moderate increase in bite force in DOX males and none in DOX females, the increase in masseter mass in males indicates a potentially positive impact on jaw muscles. Our data suggest a sexual dimorphism in the role of mstn, and as such investigations into the sex-specific outcomes is warranted.

An editorial in Science (Alberts, 2012) has expressed the need to teach "real science," firmly based on hands-on and inquiry methodology. Also in a recent article, Stevens (2011) highlighted the contrast between the emphasis that federal agencies and professional associations place on science outreach, and the scarcity of support for such activities at the classroom level. To bridge this gap, we have developed a way to redefine science education by involving college students and faculty in "real science" outreach. Incorporating outreach activities into a college science curriculum is an efficient means to affect not only future scientists but also the world at large with which scientists need to communicate. In this paper we describe a Science Education Partnership Award (SEPA) project. The project has been implemented in a minority setting, at a small college of allied health located in one of the most underserved areas of Los Angeles. Some of its outcomes were presented at two Society for Neuroscience meetings (Gizerian et al., 2009; Ayers and de Lacalle, 2010), before being also discussed as an example of outreach program during the FUN summer workshop in Pomona (California) in 2011. This project entails the development of a working partnership between K-12 institutions and college science students and faculty. Participation was voluntary (but college students could request community service credit) and most importantly built on student interests and connections with the community. The three components are described in terms of efficacy (i.e., impact on college students' communication skills) and community value (i.e., impact on educational outcomes for the partner K-12 institution).

Gonadal hormones can influence the morphology and function of glial cells, particularly astrocytes. Here we explore the hypothesis that 17beta-estradiol (E2) exerts a positive effect on astrocytes within the region of the cholinergic neurons of the basal forebrain, an area heavily implicated in memory and attentional processes. Female rats were ovariectomized at 3 months of age and lesioned with the immunotoxin 192 IgG-saporin before receiving a subcutaneous pellet containing 0.25mg of estrogen or placebo, released over 60 days. The control, non-ovariectomized group was treated identically. At the end of the treatment, we used image analysis procedures to evaluate changes in the levels of glial fibrillary acidic protein (GFAP) expression in the area of the lesion. Infusion of the immunotoxin induced a slight increase in GFAP expression in some subjects, compared to the contralateral side. However, when differences within animals where factored in, GFAP expression in ovariectomized animals treated with E2 was undistinguishable from intact controls. By contrast, in ovariectomized animals treated with placebo, GFAP expression was significantly higher. These results suggest that E2 deprivation may exacerbate the effects of an immunotoxic lesion, and, more importantly, that E2 administration may contribute to structural recovery of lesioned cholinergic neurons by blocking GFAP expression in the area. These results are particularly relevant in the context of female aging and postmenopausal dementia, and further highlight other potential levels at which to design interventions to preserve an intact cholinergic system, which may be crucial to prevent Alzheimer's disease.

This review focuses on the effects of estrogen on neuronal morphology. Over the last decade neuroscientists have accumulated a wealth of information confirming the trophic effects of 17beta-estradiol on a variety of brain regions, including changes of hippocampal spine density and axonal outgrowth and retraction in hypothalamic nuclei, as well as other measures of structural reorganization that could underlie some of the cognitive benefits attributed to this hormone. Overall, results from a variety of investigators suggest that 17beta-estradiol is a potent structural signal that can drive developmental as well as adult plastic events in a variety of brain regions, not only those implicated in reproduction, but also in a diversity of functions. Most notably, these structural modifications that subserve cyclic physiological processes, can also be activated in other brain regions to protect and even reverse structural neurodegenerative processes. The data presented here are not exhaustive, but rather meant to provide a few examples of these structural effects of 17beta-estradiol that could have important implications for clinical practice.

Over the last decade neuroscientists have accumulated a wealth of information confirming the trophic effects of 17beta-estradiol (E2) on a variety of brain regions, such as the effects on hippocampal spine density, as well as other measures of structural reorganization. Here, we explore the hypothesis that E2 exerts a positive trophic effect on the cholinergic neurons of the basal forebrain, an area heavily implicated in memory and attentional processes. Female rats were ovariectomized at 3 months of age and lesioned with the immunotoxin 192 IgG-saporin before receiving a subcutaneous pellet containing .25 mg of estrogen or placebo, released over 60 days. The control, non-ovariectomized group was treated identically. At the end of the treatment, the brains were histologically prepared and we used image analysis procedures to evaluate changes in the dendritic arborization of surviving cholinergic neurons. As expected, infusion of the immunotoxin induced a reduction in dendritic arborization in all subjects, but was significantly different from control values only in ovariectomized rats. When differences within animals were factored in, dendritic size in ovariectomized animals treated with E2 was undistinguishable from intact controls. By contrast, in ovariectomized animals treated with placebo, dendritic length remained significantly reduced. These results suggest that E2 can not only protect but also reverse structural neurodegenerative processes in cholinergic neurons. Our data is particularly relevant in the context of female aging and postmenopausal dementia, since preserving an intact cholinergic system may be crucial to prevent at least some of the cognitive decline that occurs in Alzheimer's disease.

Purpose: To investigate the plastic capacity of the cholinergic system in a partial animal model of Alzheimer's disease., Methods: Rats received unilateral lesions of the horizontal diagonal band of Broca (HDB) using a cholinergic-specific toxin, 192 IgG-saporin. After the appropriate survival time (2, 4, 8, 12 and 24 weeks post-lesion) rats were sacrificed and the brains were prepared for histology. Immunocytochemical and morphometric techniques were employed to quantify the cholinergic neurons surviving the lesion and to measure the density of cortical cholinergic fibers., Results: Cell counts revealed on average a 60% reduction in cholinergic neurons on the lesioned side, compared to the spared side. This cell loss was permanent, that is, there was no significant change in the amount of cell loss over time. In correlation with this cell loss, cholinergic fibers in the target area, the entorhinal cortex (EC), were also reduced such that the density of acetylcholinesterase (AChE)-stained fibers on the lesioned side was 44% of the spared side. The density of cholinergic fibers in the EC increased significantly between 2 and 12 weeks post-lesion (p=0.0216) but remained stable at that level by 24 weeks after the lesion., Conclusions: Following a cholinergic-specific lesion, a compensatory mechanism is activated in the basal forebrain cholinergic system, such that surviving neurons, projecting to the same target, extend their terminals to occupy the denervated area. It remains to be investigated whether these sprouts are able to establish proper synaptic connections and make a functional recovery in this particular system.

In the present study, we examined the ability of estrogen to enhance cholinergic neurite arborization in vitro and identified the signal transduction cascade associated with this effect. Basal forebrain primordia collected from rat pups on postnatal day 1 were cultured for 2 weeks and then treated with 5 nm 17beta-estradiol for 24 hr. Cholinergic neurons were identified immunocytochemically with an antibody against the vesicular acetylcholine transporter and digitally photographed. Morphological analysis indicated that female cultures respond to estrogen treatment with an increase in total neurite length per neuron (4.5-fold over untreated controls) and in total branch segment number per neuron (2.3-fold over controls). In contrast, there was no change in total neurite length per neuron in male cultures, and we also observed a decrease in total branch segment number per neuron (0.5-fold below controls). Detailed histograms indicated that estrogen increases primary and secondary branch length and number and also increases terminal neuritic branches to the seventh order in female cultures. In a second set of experiments, we investigated the signal transduction cascade involved in this response, and found that an upstream extracellular signal-regulated kinase (ERK) inhibitor blocked the ability of estrogen to enhance outgrowth in female cultures. Our study provides strong evidence in support of the fact that the ERK pathway is required for estrogen-induced structural plasticity in the cholinergic system of female rats. Understanding the intracellular processes that underlie the response of cholinergic neurons to estrogen provides a necessary step in elucidating how cholinergic neurons can be particularly susceptible to degeneration in postmenopausal women.

Galanin (GAL) and GAL receptors (GALR) are overexpressed in limbic brain regions associated with cognition in Alzheimer disease (AD). The functional consequences of this overexpression are unclear. Because GAL inhibits cholinergic transmission and restricts long-term potentiation in the hippocampus, GAL overexpression may exacerbate clinical features of AD. In contrast, GAL expression increases in response to neuronal injury, and galaninergic hyperinnervation prevents the decreased production of protein phosphatase 1 subtype mRNAs in cholinergic basal forebrain neurons in AD. Thus, GAL may also be neuroprotective for AD. Further elucidation of GAL activity in selectively vulnerable brain regions will help gauge the therapeutic potential of GALR ligands for the treatment of AD.

A new type of self-assembling peptide (sapeptide) scaffolds that serve as substrates for neurite outgrowth and synapse formation is described. These peptide-based scaffolds are amenable to molecular design by using chemical or biotechnological syntheses. They can be tailored to a variety of applications. The sapeptide scaffolds are formed through the spontaneous assembly of ionic self-complementary beta-sheet oligopeptides under physiological conditions, producing a hydrogel material. The scaffolds can support neuronal cell attachment and differentiation as well as extensive neurite outgrowth. Furthermore, they are permissive substrates for functional synapse formation between the attached neurons. That primary rat neurons form active synapses on such scaffold surfaces in situ suggests these scaffolds could be useful for tissue engineering applications. The buoyant sapeptide scaffolds with attached cells in culture can be transported readily from one environment to another. Furthermore, these peptides did not elicit a measurable immune response or tissue inflammation when introduced into animals. These biological materials created through molecular design and self assembly may be developed as a biologically compatible scaffold for tissue repair and tissue engineering.

Astroglial cells secrete a variety of factors that contribute to the regulation of neurite initiation and continued outgrowth, among them proteases and protease inhibitors. An alteration in the balance between these proteins has been implicated in Alzheimer's disease, resulting in an accumulation of thrombin:protease nexin 1 (PN1) complexes in the brains of these patients. This report aims at providing a biochemical explanation for this phenomenon. We show that human astrocytoma cells bind and internalize thrombin and thrombin:PN1 complexes efficiently by a PN1-dependent mechanism. Binding was potently inhibited by soluble heparin and did not occur with the mutant PN1 (K7E) deficient in heparin binding. Receptor-associated protein, an antagonist of the low-density lipoprotein receptor-related protein (LRP), inhibited internalization of thrombin by the astrocytoma cells, but did not affect cell-surface binding. The results are consistent with a mechanism by which astrocytoma cells clear thrombin in a sequential manner: thrombin is first complexed with PN1, then bound to cell-surface heparins, and finally internalized by LRP. This mechanism provides a link between the neuronal growth regulators thrombin and PN1 and proteins genetically associated with Alzheimer's disease, such as LRP.

We used a recombinant adeno-associated virus vector (AAV) to deliver a foreign gene, green fluorescent protein (GFP), into mature neurons in adult rat CNS in vivo. Microinjections of AAV as small as 50 nl transduced hundreds of neurons at the injection site. There was virtually no retrograde transport as fewer than one neuron per brain was found distant from the injection site that exhibited GFP immunoreactivity. The gene product, GFP, filled the entire neuronal cytoplasmic compartment; GFP immunoreactivity was robust in cell bodies, axons, and nerve terminals. There was no tissue damage at the injection sites or pathogenicity indicated by changes in astrocytic or microglial markers. There was no inflammatory response as judged by leukocytic invasion. Gene expression in transduced cells was robust and apparently permanent: there was no evidence of phenotypic reversion up to 12 weeks following infection. AAV is an excellent vector for introducing foreign genes into mature CNS neurons. Not only might it be an ideal vehicle for gene therapy, but also the GFP-containing AAV presents a new strategy for tracing long axonal pathways in the CNS, which is difficult with current tracers (PHAL, biotinylated dextrans)., (Copyright 1998 Elsevier Science B.V.)

The present experiments were designed to determine the effect that lesions of the basal forebrain cholinergic system exert on cholinergic interneurons within the entorhinal cortex (EC) in the rat. Unilateral infusion of 192 IgG-saporin into the nucleus of the horizontal diagonal band of Broca (HDB) decreased the number of ipsilateral choline acetyltransferase immunoreactive (ChAT-ir) neurons by 54%. Two-four weeks after the lesion, the ipsilateral EC exhibited a moderate but significant loss of ChAT-ir fibres and interneurons. Adjacent sections revealed a parallel loss of vasoactive intestinal polypeptide (VIP) immunoreactivity. Cell counts in the cingulate cortex were unaffected, suggesting that this effect was indeed specific to the main target area for HDB neurons. Ibotenic acid lesions also induced a significant 36% decrease in the number of cholinergic neurons in the ipsilateral HDB, and disappearance of ChAT terminals in the EC, whereas the number of ChAT-ir neurons in the EC was unchanged. Since ibotenic acid affects all cells and not only cholinergic ones, our results suggest that the specific degeneration of cholinergic neurons in the HDB after 192 IgG-saporin treatment could be inducing transsynaptic effects on their targets. Injections of 192 IgG-saporin directly into the EC also lesioned the cholinergic projection from the HDB, but had no effect on the intrinsic population. Eight weeks after immunolesion, the number of interneurons immunoreactive for ChAT and VIP in the EC had returned to normal values, and persisted for as long as 6 months after the lesion. By contrast, ChAT-ir neurons in the HDB were permanently lost. Our results suggest that the transient down-regulation of the cholinergic phenotype in entorhinal cortex interneurons could be a manifestation of activity-dependent plasticity, and that the loss of cholinergic innervation from the basal forebrain could be responsible for these effects through an imbalance of inputs. We hypothesize that the recovery of the phenotypic expression of entorhinal interneurons could be due to a recovery in their innervation, perhaps from sprouting axons in the same fields, belonging to surviving cholinergic neurons in the basal forebrain.

The age-related neuronal changes in mnemonic centres were studied in 37 human and 36 rats (Wistar) brains. The age of the brains (without cerebral alterations) was uniformly distributed along the lifespan (16-86 years in humans and 1-36 months in rats). The results showed parallel changes in humans and rats. The neuronal loss oscillated between 3 and 64%, mean 32%. Neuronal death was a continuous process, although there were differences according the centres, for instance, the higher loss was found in the first half of life in the cortex entorhinalis and hippocampus (rat), and the contrary happened in the dorsolateral and basomedial nucleus of amygdala. In other centres, e.g., mamilla body, basal nucleus of Meynert etc. the loss was quite uniform. The modification in nuclear size showed 3 different phases: there was an initial period in which the nuclear area decreased, a second period with an increase and, in the last period, there was a stabilization in humans and a conspicuous decrease in rats. The nuclear enlargement is interpreted as result of the loss of redundance in nervous centres and the stabilization or atrophy as a consequence of loss of the neuronal plasticity.

The cholinergic innervation of the hippocampal formation is thought to play an important role in memory processes, but its organization in humans has not been described in detail. We studied the cholinergic innervation of the human hippocampal formation by means of immunohistochemistry with polyclonal antisera directed against acetylcholinesterase (AChE), choline acetyltransferase (ChAT), and the low-affinity (p75) nerve growth factor receptor (NGFR). The density of ChAT-like immunoreactive (ChAT-li) fibers differed substantially among the various regions, in general paralleling the pattern of AChE-li staining. One notable exception was the presence of AChE-li cell bodies. In contrast, ChAT immunoreactivity was associated only with fibers and terminals. NGFR-li staining corresponded closely to the ChAT-li fiber pattern. ChAT-li fibers in the CA fields diffusely filled the stratum pyramidale and extended into the stratum oriens and radiatum as well. The highest density was consistently observed in CA4 and CA3 subfields. Staining decreased from CA4 to CA1 and was substantially less dense in the subicular complex. In the entorhinal cortex, the ChAT- and NGFR-li fiber innervation displayed a laminar pattern, most intense over the nests of cells in layer II. There was a trend towards an age-related reduction in the density of ChAT- and AChE-li fibers and terminals. Nonetheless, we also found a surprisingly conserved NGFR-li innervation and the presence of occasional NGFR-li pyramidal cells, providing evidence of a plastic response in the brains of the elderly patients.

Cholinergic innervation of the human cerebellum was investigated immunocytochemically by using a polyclonal rabbit antiserum against choline acetyltransferase. Immunoreactive structures were found throughout the cerebellar cortex but were localized predominantly in the vermis, flocculus, and tonsilla. These included 1) a population of Golgi cells in the granular layer; 2) a subpopulation of mossy fibers and glomerular rosettes; 3) thin, varicose fibers closely associated with the Purkinje cell layer and the molecular layer; and 4) a relatively dense network of fibers and terminals contributing to the glomerular formations in the granular layer. In the cerebellar nuclei, some cells stained positively for choline acetyltransferase, and a terminal field pattern could be detected with a distinct but sparse network of varicose fibers. Acetylcholine appears to be a primary transmitter in the vestibulocerebellar pathways at several levels, which may account for the potent effects of muscarinic antagonists in diminishing vestibular vertigo in humans.

Parkinson's disease is thought to cause degeneration of melanin-pigmented catecholaminergic neurons throughout the brainstem, but little quantitative information is available on the fate of catecholaminergic neurons associated with the dorsal vagal complex or medullary reticular formation. We therefore examined these neurons in the normal human medulla and in the brains of patients with Parkinson's disease, using both a melanin stain and immunohistochemical methods with an antiserum against tyrosine hydroxylase. The greatest numbers of catecholaminergic neurons in the ventrolateral reticular formation (A1/C1 group) were located in the far rostral medulla, whereas the largest populations of catecholaminergic cells in the dorsal vagal complex (A2/C2 group) were found at the level of the area postrema. No loss of cells was observed in the A1/C1 group in the parkinsonian brains. In contrast, the A2/C2 group showed moderate loss of neurons, most marked at the level of the area postrema. This difference was entirely due to the loss of neurons in the medial component of the A2 group, a population that normally is only lightly pigmented, while the heavily pigmented neurons in the ventral and intermediate components of the A2 complex were unaffected. Parkinson's disease causes degeneration only of selected populations of medullary catecholaminergic neurons, without apparent relationship to the extent of melanin pigmentation.