Publications by authors named "K A Dunlap"

250 Publications

The estrous cycle and skeletal muscle atrophy: Investigations in rodent models of muscle loss.

Exp Physiol 2021 Sep 26. Epub 2021 Sep 26.

Department of Neurology, Beth Israel Deaconess Medical Center and Harvard Medical School, 330 Brookline Avenue, Boston, MA, 02215, United States.

New Findings: What is the central question of this study? Is the estrous cycle affected during disuse atrophies and if so, how do estrous cycle changes relate to musculoskeletal outcomes? What is the main finding and its importance? Rodent estrous cycles are altered during disuse atrophy, which corresponds to musculoskeletal outcomes. However, the estrous cycle does not appear changed in Lewis Lung Carcinoma, which corresponded to no differences in muscle size compared to healthy controls. These findings suggest a relationship between estrous cycle and muscle size during atrophic pathologies.

Abstract: Recent efforts have focused on further understanding female muscle physiology during exposure to muscle atrophic stimuli. A key feature of female rodent physiology is the estrous cycle. However, how such stimuli interact with the estrous cycle to influence muscle health remains uninvestigated.

Aim: To investigate the impact of muscle atrophic stimuli on the estrous cycle and how these alterations correlate with musculoskeletal outcomes.

Methods: A series of experiments were performed, including hindlimb unloading (HU), hindlimb unloading followed by 24 hours of reloading, (HU+24hrs Recovery), hindlimb unloading combined with dexamethasone treatment (HU+DEXA), and Lewis Lung Carcinoma (LLC) in female rodents. Estrous cycle phase was assessed throughout each intervention and correlated with musculoskeletal outcomes.

Results: Seven or fourteen days of HU increased duration in diestrus or metestrus (D/M, low hormones) and negatively correlated with gastrocnemius mass. Time spent in D/M also negatively correlated with changes in grip strength and bone density after HU, as well as muscle recovery 24 hours after the cessation of HU. The addition of dexamethasone strengthened these relationships between time in D/M and reduced musculoskeletal outcomes. However, in LLC animals, estrous cyclicity did not differ from control animals and time spent in D/M did not correlate with either gastrocnemius mass or tumor burden. In vitro experiments suggest estrogen-induced enhanced protein synthesis may protect against muscle atrophy.

Conclusion: Muscle atrophic insults correlated with estrous cycle alterations which, are associated with deteriorations to musculoskeletal outcomes. The magnitude of estrous cycle alterations depend on the atrophic stimuli. This article is protected by copyright. All rights reserved.
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http://dx.doi.org/10.1113/EP089962DOI Listing
September 2021

Vocal and Electric Fish: Revisiting a Comparison of Two Teleost Models in the Neuroethology of Social Behavior.

Front Neural Circuits 2021 19;15:713105. Epub 2021 Aug 19.

Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, United States.

The communication behaviors of vocal fish and electric fish are among the vertebrate social behaviors best understood at the level of neural circuits. Both forms of signaling rely on midbrain inputs to hindbrain pattern generators that activate peripheral effectors (sonic muscles and electrocytes) to produce pulsatile signals that are modulated by frequency/repetition rate, amplitude and call duration. To generate signals that vary by sex, male phenotype, and social context, these circuits are responsive to a wide range of hormones and neuromodulators acting on different timescales at multiple loci. Bass and Zakon (2005) reviewed the behavioral neuroendocrinology of these two teleost groups, comparing how the regulation of their communication systems have both converged and diverged during their parallel evolution. Here, we revisit this comparison and review the complementary developments over the past 16 years. We (a) summarize recent work that expands our knowledge of the neural circuits underlying these two communication systems, (b) review parallel studies on the action of neuromodulators (e.g., serotonin, AVT, melatonin), brain steroidogenesis ( aromatase), and social stimuli on the output of these circuits, (c) highlight recent transcriptomic studies that illustrate how contemporary molecular methods have elucidated the genetic regulation of social behavior in these fish, and (d) describe recent studies of mochokid catfish, which use both vocal and electric communication, and that use both vocal and electric communication and consider how these two systems are spliced together in the same species. Finally, we offer avenues for future research to further probe how similarities and differences between these two communication systems emerge over ontogeny and evolution.
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http://dx.doi.org/10.3389/fncir.2021.713105DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8418312PMC
August 2021

More Than Their Test Scores: Redefining Success with Multiple Mini-Interviews.

Med Sci Educ 2020 Sep 2;30(3):1049-1060. Epub 2020 Jul 2.

Public Health Sciences, University of North Carolina at Charlotte, Charlotte, NC USA.

Introduction: Medical schools are shifting to a holistic approach for admissions. As non-cognitive abilities become more valued in the medical field and admissions become more competitive, multiple mini-interviews (MMI) are becoming increasingly common in selection criteria. The purpose of this article is to examine the relationship among admissions criteria to create a predictive model of acceptance to medical school. This article also aims to examine, among matriculated students, the relationship between MMI and traditional academic success, and the relationship between MMI scores and clinical competence and academic accolades.

Methods: This longitudinal study followed a cohort of students from the MMI process through the first two pre-clinical years at a medical school in the southeastern USA. Multiple logistic regression with backward elimination variable selection was used to examine the relationship between admission criteria and acceptance. A multivariate multinomial ordered probit model was used to assess the relationship between MMI and traditional academic success among matriculated students. Simple linear regression models were used to assess relationships between MMI and Objective Structured Clinical Examination (OSCE) scores and honors nomination.

Results: MMI are among eight significant predictors of acceptance. Among matriculated students, there were weak negative associations between MMI and traditional academic success; however, all but one relationship was statistically non-significant. There was not a significant association between MMI and OSCE scores or academic accolades.

Conclusions: While MMI can identify students with non-cognitive skills needed to be a good physician, continued assessment needs to be incorporated in their education.
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http://dx.doi.org/10.1007/s40670-020-01013-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8368390PMC
September 2020

Sled dogs as a model for PM2.5 exposure from wildfires in Alaska.

Environ Int 2021 11 19;156:106767. Epub 2021 Jul 19.

University of Alaska, Fairbanks Institute of Arctic Biology, 2140 Koyukuk Drive Fairbanks, AK 99775, United States; University of Alaska Fairbanks Department of Chemistry and Biochemistry, 900 Yukon Drive Fairbanks, AK 99775, United States. Electronic address:

Particulate matter 2.5 (PM2.5) exposure induces oxidative stress associated with many negative health outcomes such as respiratory disorders, cardiovascular disease and neurodegenerative disease. Research shows that diet and exercise can improve antioxidant defense against oxidative stress. This study is the first to use an Arctic animal model to investigate the cumulative effects of two lifestyle interventions on the antioxidant response before, during, and after ambient PM 2.5 exposure from wildfire: antioxidant supplementation (Arthrospira platensis) and exercise. In a two-factorial, longitudinal design, this study divided sled dogs (n = 48) into four groups (exercise and supplemented, exercise, supplemented, and control) to (1) test the effects of a 30-day exercise and antioxidant supplementation protocol on antioxidant response; and (2) measure the antioxidant response of all groups during and after a natural wildfire event. Commercial assays for total antioxidant power (TAP) and the enzymatic antioxidant superoxide dismutase (SOD) were used as markers for antioxidant status and response. During the forest fire, SOD was increased 5- to 10-fold over pre/post-exposure levels in all groups suggesting an endogenous upregulation of defense systems in response to the acute environmental stress. TAP was lower in all groups at peak PM2.5 exposure compared to 48 h after peak exposure in all groups except the exercise alone group which may indicate that exercise offers improved endogenous defense.
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http://dx.doi.org/10.1016/j.envint.2021.106767DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8385229PMC
November 2021

Social stimuli increase activity of adult-born cells in the telencephalon of zebrafish (Danio rerio).

J Exp Biol 2021 Aug 18;224(16). Epub 2021 Aug 18.

Instituto Gulbenkian de Ciências, Oeiras, Portugal.

Fish have particularly high levels of adult neurogenesis, and this high neurogenic capacity may contribute to behavioural plasticity. While it is known that adult-born cells can differentiate into neurons and incorporate into neural circuits, it is unclear whether they are responsive to external stimuli and are thereby capable of contributing to behavioural change. We tested whether cells born in the telencephalon of adult zebrafish are activated by social stimuli. We marked cell birth with BrdU and, 40 days later, exposed fish to brief (15 min) visual social stimuli and assayed cellular activity through immunolocalization of phospho-S6-ribosomal protein (pS6). BrdU+/pS6+ co-labelled cells were found in six brain regions, and, in four regions [dorsal (D), dorsomedial (Dm) and dorsolateral (Dl) zones of the dorsal telencephalon and pre-optic area (POA)], the number of co-labelled cells and fraction of BrdU+ cells that labelled positive for pS6 increased during social stimulation. These results are consistent with the hypothesis that adult-born neurons play a role in regulating social behaviour.
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http://dx.doi.org/10.1242/jeb.242253DOI Listing
August 2021
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