A novel process for H&E, immunofluorescence, and imaging mass cytometry on a single slide with a concise analytics pipeline.

Imaging mass cytometry (IMC) is a powerful spatial technology that utilizes cytometry time of flight to acquire multiplexed image datasets with up to 40 markers, via metal-tagged antibodies. Recent advances in IMC have led to the inclusion of RNAScope probes and multiple new analysis pipelines have led to faster analyses and better results. However, IMC still suffers from lower resolution (1 µm2 pixels) and relatively small regions of interest (ROIs) (<2 mm2 ) compared to other, light-based microscope technologies. Capturing higher-resolution images on serial sections causes great difficulty when attempting to align cells and structures across serial sections, especially when observing smaller cell types and structures. Therefore, we demonstrate the combination of H&E and multiplex immunofluorescence imaging, for much higher resolution of the structural and cellular compartments found throughout the entire tissue section, with the high-dimensionality of IMC for specific ROIs on a single slide. Additionally, we demonstrate a simple and effective open-source cell segmentation and IMC analysis pipeline with previously published and freely available software.

Examining Mechanisms for Voltage-Sensitive Calcium Channel-Mediated Secretion Events in Bone Cells.

In addition to their well-described functions in cell excitability, voltage-sensitive calcium channels (VSCCs) serve a critical role in calcium (Ca2+)-mediated secretion of pleiotropic paracrine and endocrine factors, including those produced in bone. Influx of Ca2+ through VSCCs activates intracellular signaling pathways to modulate a variety of cellular processes that include cell proliferation, differentiation, and bone adaptation in response to mechanical stimuli. Less well understood is the role of VSCCs in the control of bone and calcium homeostasis mediated through secreted factors. In this review, we discuss the various functions of VSCCs in skeletal cells as regulators of Ca2+ dynamics and detail how these channels might control the release of bioactive factors from bone cells. Because VSCCs are druggable, a better understanding of the multiple functions of these channels in the skeleton offers the opportunity for developing new therapies to enhance and maintain bone and to improve systemic health.

Pediatric meniscus morphology varies with age: a cadaveric study.

PURPOSE: In adolescent patients, meniscal tear injury can occur either in isolation (e.g., discoid lateral meniscus tears) or in association with other traumatic injuries including tibial eminence fracture or ACL tear. Damage to meniscal integrity has been shown to increase contact pressure in articular cartilage, increasing risk of early onset osteoarthritis. In symptomatic patients failing conservative management, surgical intervention via meniscus repair or meniscus transplant is indicated. The purpose of this study was to evaluate the radial dimensions of pediatric menisci throughout development. The hypothesis was that the average radial meniscus dimensions will increase as specimen age increases, and mean medial and lateral region measurements will increase at a linear rate. METHODS: Seventy-eight skeletally immature knee cadaver specimens under age 12 years were included in this study. The meniscal specimens were photographed in the axial view with ruler in the plane of the tibial plateau and analyzed using computer-aided design (CAD) software (Autodesk Fusion 360). Measurements were taken from inner to outer meniscus rims at five 45 degree intervals using the clockface as a reference (12:00, 1:30, 3:00, 4:30, 6:00), and total area of meniscus and tibial plateau was recorded. Generalized linear models were used to evaluate the associations of radial width measurements with age, tibial coverage, and lateral vs. medial meniscus widths. RESULTS: All radial width measurements increased significantly with specimen age (p ≤ 0.002), and all lateral-medial meniscal widths increased (p < 0.001). The anterior zones of the meniscus were found to increase at the slowest rate compared to other regions. Tibial plateau coverage was found to not significantly vary with age. CONCLUSIONS: Meniscus radial width and lateral-medial meniscus width are related to age. The anterior width of the meniscus varied least with age. Improved anatomic understanding may help surgeons more effectively plan for meniscus repair, discoid resection/saucerization/repair, and also support appropriate selection of meniscus allograft for transplantation.

Effects of Gabapentin and Pregabalin on Calcium Homeostasis: Implications for Physical Rehabilitation of Musculoskeletal Tissues.

PURPOSE OF REVIEW: In this review, we discuss the mechanism of action of gabapentinoids and the potential consequences of long-term treatment with these drugs on the musculoskeletal system. RECENT FINDINGS: Gabapentinoids, such as gabapentin (GBP) and pregabalin (PGB) were designed as antiepileptic reagents and are now commonly used as first-line treatment for neuropathic pain and increasingly prescribed off-label for other pain disorders such as migraines and back pain. GBP and PGB exert their analgesic actions by selectively binding the α2δ1 auxiliary subunit of voltage-sensitive calcium channels, thereby inhibiting channel function. Numerous tissues express the α2δ1 subunit where GBP and PGB can alter calcium-mediated signaling events. In tissues such as bone, muscle, and cartilage, α2δ1 has important roles in skeletal formation, mechanosensation, and normal tissue function/repair that may be affected by chronic use of gabapentinoids. Long-term use of gabapentinoids is associated with detrimental musculoskeletal outcomes, including increased fracture risk. Therefore, understanding potential complications is essential for clinicians to guide appropriate treatments.

Nitrated meat products are associated with mania in humans and altered behavior and brain gene expression in rats.

Mania is a serious neuropsychiatric condition associated with significant morbidity and mortality. Previous studies have suggested that environmental exposures can contribute to mania pathogenesis. We measured dietary exposures in a cohort of individuals with mania and other psychiatric disorders as well as in control individuals without a psychiatric disorder. We found that a history of eating nitrated dry cured meat but not other meat or fish products was strongly and independently associated with current mania (adjusted odds ratio 3.49, 95% confidence interval (CI) 2.24-5.45, p < 8.97 × 10-8). Lower odds of association were found between eating nitrated dry cured meat and other psychiatric disorders. We further found that the feeding of meat preparations with added nitrate to rats resulted in hyperactivity reminiscent of human mania, alterations in brain pathways that have been implicated in human bipolar disorder, and changes in intestinal microbiota. These findings may lead to new methods for preventing mania and for developing novel therapeutic interventions.

Skeletal Functions of Voltage Sensitive Calcium Channels.

Voltage-sensitive calcium channels (VSCCs) are ubiquitous multimeric protein complexes that are necessary for the regulation of numerous physiological processes. VSCCs regulate calcium influx and various intracellular processes including muscle contraction, neurotransmission, hormone secretion, and gene transcription, with function specificity defined by the channel's subunits and tissue location. The functions of VSCCs in bone are often overlooked since bone is not considered an electrically excitable tissue. However, skeletal homeostasis and adaptation relies heavily on VSCCs. Inhibition or deletion of VSCCs decreases osteogenesis, impairs skeletal structure, and impedes anabolic responses to mechanical loading. RECENT FINDINGS: While the functions of VSCCs in osteoclasts are less clear, VSCCs have distinct but complementary functions in osteoblasts and osteocytes. PURPOSE OF REVIEW: This review details the structure, function, and nomenclature of VSCCs, followed by a comprehensive description of the known functions of VSCCs in bone cells and their regulation of bone development, bone formation, and mechanotransduction.

Phys-MAPS: a programmatic physiology assessment for introductory and advanced undergraduates.

We describe the development of a new, freely available, online, programmatic-level assessment tool, Measuring Achievement and Progress in Science in Physiology, or Phys-MAPS ( http://cperl.lassp.cornell.edu/bio-maps ). Aligned with the conceptual frameworks of Core Principles of Physiology, and Vision and Change Core Concepts, Phys-MAPS can be used to evaluate student learning of core physiology concepts at multiple time points in an undergraduate physiology program, providing a valuable longitudinal tool to gain insight into student thinking and aid in the data-driven reform of physiology curricula. Phys-MAPS questions have a modified multiple true/false design and were developed using an iterative process, including student interviews and physiology expert review to verify scientific accuracy, appropriateness for physiology majors, and clarity. The final version of Phys-MAPS was tested with 2,600 students across 13 universities, has evidence of reliability, and has no significant statement biases. Over 90% of the physiology experts surveyed agreed that each Phys-MAPS statement was scientifically accurate and relevant to a physiology major. When testing each statement for bias, differential item functioning analysis demonstrated only a small effect size (<0.008) of any tested demographic variable. Regarding student performance, Phys-MAPS can also distinguish between lower and upper division students, both across different institutions (average overall scores increase with each level of class standing; two-way ANOVA, P < 0.001) and within each of three sample institutions (each ANOVA, P ≤ 0.001). Furthermore, at the level of individual concepts, only evolution and homeostasis do not demonstrate the typical increase across class standing, suggesting these concepts likely present consistent conceptual challenges for physiology students.

Whey Protein Supplementation and Higher Total Protein Intake Do Not Influence Bone Quantity in Overweight and Obese Adults Following a 36-Week Exercise and Diet Intervention.

BACKGROUND: Controversy exists concerning the effects of higher total protein intake (TPro) on bone health, which may be associated with reduced bone mineral density (BMD). However, whey protein (WP) may induce bone formation because of its basic component, milk basic protein. OBJECTIVE: This study assessed the effects of WP supplementation, TPro, and change in TPro (postsupplementation - presupplementation) on BMD and bone mineral content (BMC; total body, lumbar spine, total femur, and femoral neck) in overweight and class I obese middle-aged adults following an exercise intervention. METHODS: This analysis used data from a double-blind, randomized, placebo-controlled 36-wk WP supplementation trial, wherein participants consumed a 1.7-MJ (400-kcal) supplement (0, 20, 40, or 60 g WP/d) along with their otherwise unrestricted diet while participating in a resistance and aerobic exercise intervention (3 d/wk). TPro was the summation of WP and habitual dietary intakes (4-d food record). Statistical analyses for WP were based on group and bone data [n = 186, 108 women; mean ± SD age: 49 ± 8 y; body mass index (BMI; in kg/m2): 30.1 ± 2.8], whereas TPro was based on dietary and bone data (n = 113, 70 women; age 50 ± 8 y; BMI 30.1 ± 2.9). RESULTS: WP supplementation, regardless of dose, did not influence BMD or BMC following the intervention. By using a multiple linear regression model, TPro (expressed as g/d or g · kg-1 · d-1) and change in TPro (expressed as g/d) were not associated with responses over time in total or regional BMD or BMC. By using a cluster analysis approach [<1.0 (n = 41), 1.0-1.2 (n = 28), and ≥1.2 g · kg-1 · d-1 (n = 44)], TPro was also not associated with responses in total or regional BMD or BMC over time. CONCLUSION: WP supplementation and total dietary protein intake did not negatively or beneficially influence bone quantity in overweight and obese adults during a 9-mo exercise intervention. This trial was registered at clinicaltrials.gov as NCT00812409.

Barriers to implementing diagnostic domestic violence screening.

In the United Kingdom, Australia, the United States of America and Europe, universal and routine screening is recommended for pregnant women, extending into the postnatal period. However, the lack of self-confidence among midwives and midwifery students, in implementing diagnostic domestic violence screening, is consistent within the contemporary literature, and has significant implications for the health of women and their families.The evidence for this lack of confidence centres around three professional issues surrounding domestic violence screening from a midwifery context: time constraints; midwifery education; and midwives as recipients of domestic violence.

Thyroid status, insulin sensitivity and glucose tolerance in overweight and obese adults before and after 36 weeks of whey protein supplementation and exercise training.

UNLABELLED: Research suggests that subclinical hypothyroidism (SHT) influences insulin sensitivity and glucose tolerance. Reductions in thyroid stimulating hormone (TSH) concentrations are associated with exercise training (ExTr), which improves insulin sensitivity and glucose uptake. PURPOSE: A secondary analysis of previously published data was conducted to examine the relationship between SHT, TSH and glucose homeostatic control at baseline and to assess the impact of ExTr on thyroid status and how SHT affects changes in insulin sensitivity after ExTr. MATERIALS AND METHODS: Data were obtained from a 36-week ExTr and whey protein supplementation intervention trial. Subjects (n = 304, 48 ± 7 years, females = 186) were randomized to a specific whey protein group (0, 20, 40, or 60 g per day) and all subjects participated in a resistance (2 d/wk) and aerobic (1 d/wk) training program. Testing was conducted at baseline and post-intervention. RESULTS: At baseline, 36% (n = 110) and 12% (n = 35) of subjects were classified with SHT based on the TSH ≥ 3 µIU/L or TSH ≥ 4.5 µIU/L cut-offs, respectively. No association was found between baseline TSH and baseline measures of glucose homeostatic control. Whey protein supplementation did not influence intervention outcomes. Post-intervention (n = 164), no change was observed in TSH. SHT did not affect changes in insulin sensitivity following ExTr. CONCLUSION: These results support that the health benefits of ExTr for the management of insulin resistance (IR) are not blunted by SHT.

The Apparent Relation between Plasma 25-Hydroxyvitamin D and Insulin Resistance is Largely Attributable to Central Adiposity in Overweight and Obese Adults.

BACKGROUND: Research indicates that plasma 25-hydroxyvitamin D [25(OH)D] is associated with insulin resistance, but whether regional adiposity confounds this association is unclear. OBJECTIVE: This study assessed the potential influence of adiposity and its anatomical distribution on the relation between plasma 25(OH)D and insulin resistance. METHODS: A secondary analysis of data from middle-aged overweight and obese healthy adults [n = 336: 213 women and 123 men; mean ± SD (range); age: 48 ± 8 y (35-65 y); body mass index (BMI; in kg/m2): 30.3 ± 2.7 (26-35)] from West Lafayette, Indiana (40.4 °N), were used for this cross-sectional analysis. Multiple linear regression analyses that controlled for multiple covariates were used as the primary statistical model. RESULTS: Of all participants, 8.6% and 20.5% displayed moderate [20.1-37.5 nmol/L plasma 25(OH)D] to mild (37.6-49.9 nmol/L) vitamin D insufficiency, respectively. A regression analysis controlling for age, sex, race, plasma parathyroid hormone concentration, season of year, and supplement use showed that 25(OH)D was negatively associated with fasting insulin (P = 0.021). Additional regression analyses showed that total and central adiposity but not peripheral adiposity predicted low plasma 25(OH)D [total fat mass index (FMI): P = 0.018; android FMI: P = 0.052; gynoid FMI: P = 0.15; appendicular FMI: P = 0.07) and insulin resistance (homeostasis model assessment of insulin resistance: total and android FMI, P <0.0001; gynoid FMI, P = 0.94; appendicular FMI, P = 0.86). The associations of total and central adiposity with insulin resistance remained significant after adjusting for plasma 25(OH)D. However, adjusting for central adiposity but not other anatomical measures of fat distribution eliminated the association between plasma 25(OH)D and insulin resistance. CONCLUSION: Central adiposity drives the association between plasma 25(OH)D and insulin resistance in overweight and obese adults. The trial was registered at clinicaltrials.gov as NCT00812409.

Embryonic water uptake during pregnancy is stage- and fecundity-dependent in the snake Vipera aspis.

Water is a crucial resource that can profoundly impact the biology of terrestrial organisms. Early life stages are particularly sensitive to hydric constraints because water uptake is an important component of embryonic development. While amniotic eggs constitute a key innovation to terrestrial life, many vertebrates are viviparous wherein the mother must be the source of water for her developing embryos. Since most viviparous squamates are lecithotrophic (i.e., energy is supplied to the offspring as yolk deposited into pre-ovulated follicles), water is the predominant resource allocated from the mother to the offspring during development. Contrary to energy that can be stored (e.g., as fat reserves), water typically cannot be acquired in advance. Therefore, the embryos' need for water can impose significant constraints on the pregnant female. We detailed water flux during pregnancy in a viviparous snake, the aspic viper (Vipera aspis). We found that embryonic water uptake occurred mostly during the second half of pregnancy-a period dominated by somatic growth. We also found that, somewhat unexpectedly, changes in female plasma osmolality were negatively related to fecundity. This latter result suggests that water consumption by the female is especially important for large litter sizes, and thus may suggest an important sensitivity of reproductive females to environmental water availability.

Interhospital pediatric patient transfers-factors influencing rapid disposition after transfer.

OBJECTIVE: The objective of this study was to determine the incidence, demographics, and clinical course of pediatric patients rapidly discharged after transfer from outlying emergency departments (EDs) to a tertiary care pediatric ED (PED) with no additional diagnostic or therapeutic actions. METHODS: All pediatric patient charts from July 2009 to June 2010 who were transferred from 31 outlying EDs to an academic PED were reviewed for patient demographics, (age, sex, race) diagnosis, and disposition (admission, discharge). Primary outcome of interest in this study was percentage of children younger than 18 years discharged home after transfer to the tertiary care center (PED) with no additional medical or surgical procedures. Primary outcomes in terms of transferring physician ED pediatric physician versus ED nonpediatric physician (ED-NPP) and transferring hospital type were also analyzed using Fisher exact test. RESULTS: Three hundred forty-two patients transferred from outlying EDs to PED during the study period met inclusion criteria. Sixty percent (207/342) of overall transfers were in the age group 5 years or younger. Respiratory illness (27.5%) was the most common condition in all transfers. Patients transferred from EDs staffed by nonpediatric physician were more likely to be discharged home without needing additional studies or procedures. Patients transferred from EDs staffed by pediatricians were more likely to be admitted or required additional diagnostic and/or therapeutic interventions before disposition. CONCLUSIONS: Pediatric patients transferred from outlying community EDs to a PED frequently required little or no additional care. Referring hospital ED type and physician training type are associated with the need for additional workup at the pediatric emergency room.

A Case of BRASH (Bradycardia, Renal Dysfunction, Atrioventricular Node Blockade, Shock, and Hyperkalemia) Syndrome Following Initiation of a Sodium-Glucose Cotransporter-2 (SGLT-2) Inhibitor and a Loop Diuretic.

BRASH (bradycardia, renal dysfunction, atrioventricular node blockade, shock, and hyperkalemia) syndrome is a recently recognized clinical process that can be fatal if not adequately and promptly treated. As such, it is important for clinicians to recognize the syndrome. This case demonstrates an example of BRASH syndrome in a 73-year-old patient with heart failure occurring after initiation of dapagliflozin, a drug not previously associated with this phenomenon in the literature. Given the increasingly appreciated clinical utility of sodium-glucose cotransporter-2 (SGLT-2) inhibitors, prescribers must respect their potential side effects in patients with underlying comorbidities and remember the importance of re-evaluating renal function after initiation of these medications. Here, we review the pathophysiology of BRASH, the renal effects of SGLT-2 inhibitors, and the importance of educating patients on volume management and diuretic dose titration at home.

Flecainide-Induced Acute Respiratory Distress Syndrome: A Case Report.

Flecainide is an antiarrhythmic drug that rarely causes lung injury. We present a case of flecainide-induced lung injury (FILI) that resulted in acute respiratory distress syndrome (ARDS) and resolved after flecainide discontinuation and corticosteroid treatment. FILI has been shown to occur days to two years after treatment initiation. Our presented case shows that FILI can occur after at least five years of therapy and is the first to show lung injury after a period of flecainide cessation and subsequent re-initiation. Clinical impacts may be large, as flecainide becomes more commonplace in medical pharmacopeia.

Optional Exam Retakes Reduce Anxiety but may Exacerbate Score Disparities Between Students with Different Social Identities.

Use of high-stakes exams in a course has been associated with gender, racial, and socioeconomic inequities. We investigated whether offering students the opportunity to retake an exam makes high-stakes exams more equitable. Following the control value theory of achievement emotions, we hypothesized that exam retakes would increase students' perceived control over their performance and decrease the value of a single exam attempt, thereby maximizing exam performance. We collected data on exam scores and experiences with retakes from three large introductory biology courses and assessed the effect of optional exam retakes on gender, racial/ethnic, and socioeconomic disparities in exam scores. We found that Black/African American students and those who worked more than 20 h a week were less likely to retake exams. While exam retakes significantly improved student scores, they slightly increased racial/ethnic and socioeconomic disparities in scores partly because of these differences in participation rates. Most students reported that retake opportunities reduced their anxiety on the initial exam attempt. Together our results suggest that optional exam retakes could be a useful tool to improve student performance and reduce anxiety associated with high-stakes exams. However, barriers to participation must be examined and reduced for retakes to reduce disparities in scores.

Deletion of the auxiliary α2δ1 voltage sensitive calcium channel subunit in osteocytes and late-stage osteoblasts impairs femur strength and load-induced bone formation in male mice.

Osteocytes sense and respond to mechanical force by controlling the activity of other bone cells. However, the mechanisms by which osteocytes sense mechanical input and transmit biological signals remain unclear. Voltage-sensitive calcium channels (VSCCs) regulate calcium (Ca2+) influx in response to external stimuli. Inhibition or deletion of VSCCs impairs osteogenesis and skeletal responses to mechanical loading. VSCC activity is influenced by its auxiliary subunits, which bind the channel's α1 pore-forming subunit to alter intracellular Ca2+ concentrations. The α2δ1 auxiliary subunit associates with the pore-forming subunit via a glycosylphosphatidylinositol anchor and regulates the channel's calcium-gating kinetics. Knockdown of α2δ1 in osteocytes impairs responses to membrane stretch, and global deletion of α2δ1 in mice results in osteopenia and impaired skeletal responses to loading in vivo. Therefore, we hypothesized that the α2δ1 subunit functions as a mechanotransducer, and its deletion in osteocytes would impair skeletal development and load-induced bone formation. Mice (C57BL/6) with LoxP sequences flanking Cacna2d1, the gene encoding α2δ1, were crossed with mice expressing Cre under the control of the Dmp1 promoter (10 kb). Deletion of α2δ1 in osteocytes and late-stage osteoblasts decreased femoral bone quantity (P < .05) by DXA, reduced relative osteoid surface (P < .05), and altered osteoblast and osteocyte regulatory gene expression (P < .01). Cacna2d1f/f, Cre + male mice displayed decreased femoral strength and lower 10-wk cancellous bone in vivo micro-computed tomography measurements at the proximal tibia (P < .01) compared to controls, whereas Cacna2d1f/f, Cre + female mice showed impaired 20-wk cancellous and cortical bone ex vivo micro-computed tomography measurements (P < .05) vs controls. Deletion of α2δ1 in osteocytes and late-stage osteoblasts suppressed load-induced calcium signaling in vivo and decreased anabolic responses to mechanical loading in male mice, demonstrating decreased mechanosensitivity. Collectively, the α2δ1 auxiliary subunit is essential for the regulation of osteoid-formation, femur strength, and load-induced bone formation in male mice.

The ability of bone to sense and respond to forces generated during daily physical activities is essential to skeletal health. Although several bone cell types contribute to the maintenance of bone health, osteocytes are thought to be the primary mechanosensitive cells; however, the mechanisms through which these cells perceive mechanical stimuli remains unclear. Previous work has shown that voltage sensitive calcium channels are necessary for bone to sense mechanical force; yet the means by which those channels translate the physical signal into a biochemical signal is unclear. Data within this manuscript demonstrate that the extracellular α2δ1 subunit of voltage sensitive calcium channels is necessary for load-induced bone formation as well as to enable calcium influx within osteocytes. As this subunit enables physical interactions of the channel pore with the extracellular matrix, our data demonstrate the need for the α2δ1 subunit for mechanically induced bone adaptation, thus serving as a physical conduit through which mechanical signals from the bone matrix are transduced into biochemical signals by enabling calcium influx into osteocytes.

Loss of the auxiliary α2δ1 voltage-sensitive calcium channel subunit impairs bone formation and anabolic responses to mechanical loading.

Voltage-sensitive calcium channels (VSCCs) influence bone structure and function, including anabolic responses to mechanical loading. While the pore-forming (α1) subunit of VSCCs allows Ca2+ influx, auxiliary subunits regulate the biophysical properties of the pore. The α2δ1 subunit influences gating kinetics of the α1 pore and enables mechanically induced signaling in osteocytes; however, the skeletal function of α2δ1 in vivo remains unknown. In this work, we examined the skeletal consequences of deleting Cacna2d1, the gene encoding α2δ1. Dual-energy X-ray absorptiometry and microcomputed tomography imaging demonstrated that deletion of α2δ1 diminished bone mineral content and density in both male and female C57BL/6 mice. Structural differences manifested in both trabecular and cortical bone for males, while the absence of α2δ1 affected only cortical bone in female mice. Deletion of α2δ1 impaired skeletal mechanical properties in both sexes, as measured by three-point bending to failure. While no changes in osteoblast number or activity were found for either sex, male mice displayed a significant increase in osteoclast number, accompanied by increased eroded bone surface and upregulation of genes that regulate osteoclast differentiation. Deletion of α2δ1 also rendered the skeleton insensitive to exogenous mechanical loading in males. While previous work demonstrates that VSCCs are essential for anabolic responses to mechanical loading, the mechanism by which these channels sense and respond to force remained unclear. Our data demonstrate that the α2δ1 auxiliary VSCC subunit functions to maintain baseline bone mass and strength through regulation of osteoclast activity and also provides skeletal mechanotransduction in male mice. These data reveal a molecular player in our understanding of the mechanisms by which VSCCs influence skeletal adaptation.

Meal consumption is ineffective at maintaining or correcting water balance in a desert lizard, Heloderma suspectum.

Many xeric organisms maintain water balance by relying on dietary and metabolic water rather than free water, even when free water may be available. For such organisms, hydric state may influence foraging decisions, since meal consumption is meeting both energy and water demands. To understand foraging decisions it is vital to understand the role of dietary water in maintaining water balance. We investigated whether meal consumption was sufficient to maintain water balance in captive Gila monsters (Heloderma suspectum) at varying levels of dehydration. Gila monsters could not maintain water balance over long time scales through meal consumption alone. Animals fed a single meal took no longer to dehydrate than controls when both groups were deprived of free water. Additionally, meal consumption imparts an acute short-term hydric cost regardless of hydration state. Meal consumption typically resulted in a significant elevation in osmolality at 6 h post-feeding, and plasma osmolality never fell below pre-feeding levels despite high water content (~70%) of meals. These results failed to support our hypothesis that dietary water is valuable to Gila monsters during seasonal drought. When considered in conjunction with previous research, these results demonstrate that Gila monsters, unlike many xeric species, are heavily reliant on seasonal rainfall and the resulting free-standing water to maintain water balance.

Prrx1-driven LINC complex disruption in vivo does not significantly alter bone properties in 8-week male mice nor after 6-weeks voluntary wheel running.

The Linker of Nucleoskeleton and Cytoskeleton (LINC) complex serves to connect the nuclear envelope and the cytoskeleton, influencing cellular processes such as nuclear arrangement, architecture, and mechanotransduction. The role LINC plays in mechanotransduction pathways in bone progenitor cells has been well studied; however, the mechanisms by which LINC complexes govern in vivo bone formation remain less clear. To bridge this knowledge gap, we established a murine model disrupting LINC using transgenic Prx-Cre mice and floxed Tg(CAG-LacZ/EGFP-KASH2) mice. Prx-Cre mice express the Cre recombinase enzyme controlled by the paired-related homeobox gene-1 promoter, a pivotal regulator of skeletal development. Tg(CAG-LacZ/EGFP-KASH2) mice carry a lox-stop-lox flanked LacZ gene allowing for the overexpression of an EGFP-KASH2 fusion protein via cre recombinase mediated deletion of the LacZ cassette. This disrupts endogenous Nesprin-Sun binding in a dominant negative manner disconnecting nesprin from the nuclear envelope. By combining these lines, we generated a Prrx1(+) cell-specific LINC disruption model to study its impact on the developing skeleton and subsequently exercise-induced bone accrual. The findings presented here indicate Prx-driven LINC disruption (PDLD) cells exhibit no change in osteogenic and adipogenic potential compared to controls in vitro nor are there bone quality changes when compared to in sedentary animals at 8 weeks. Although PDLD animals displayed increased voluntary running activity, a 6-week exercise intervention did not significantly alter bone microarchitecture or mechanical properties.