bluuebunny/crossref_metadata_2025 huggingface dataset:
Whole‐body sweat production during exercise: Evaporative heat loss requirement or percent VO2max?
Authors: Kenny Glen P , Gagnon Daniel , Jay Ollie
Published: June 2021

Under conditions which permit full evaporation of the sweat produced, the evaporative heat loss requirement (Ereq) should determine whole‐body sweat production during exercise. Yet, most exercise temperature regulation studies employ a fixed percentage of maximum oxygen consumption (VO2max) when examining sweat production between independent groups. We therefore examined the relationship between sweat production and Ereq, as well as %VO2max during exercise. Twenty‐three males either performed exercise at different rates of metabolic heat production (200, 350, 500 W) at a fixed air temperature (30°C), or exercised at a fixed rate of metabolic heat production (290 W) at different air temperatures (30°C, 35°C, 40°C). Whole‐body sudomotor activity (i.e. evaporative heat loss, Esk) was measured directly by calorimetry. Stepwise multiple regression analysis revealed that end‐exercise values of Ereq significantly correlated with the variability in end‐exercise values of Esk (p<0.001), while %VO2max did not (p=0.690). Independently, end‐exercise Ereq explained ~95% of the variance in end‐exercise Esk values (adjusted R2=0.945). These data provide clear evidence that steady‐state sweat production during exercise is determined by Ereq, not percent of VO2max. Supported by NSERC grant RGPIN‐298159–2009 (held by GP Kenny).
Attenuation of cold‐induced shivering and tachycardia with modulators of thermosensitive TRPV1 and TRPM8 channels
Authors: Feketa Viktor , Marrelli Sean P
Published: June 2021

Background

Therapeutic hypothermia, a novel method of neuroprotection from hypoxia, is complicated by cold‐defensive shivering and tachycardia. These responses are controlled primarily by peripheral cold and warm receptors in the skin through distinct afferent neural pathways. The TRPM8 ion channel is a molecular cold sensor of the primary cold‐sensitive neurons, while TRPV1 is a warm and capsaicin receptor within the afferent pathway for skin warming. Our objective was to test if pharmacological modulation of TRPV1 and TRPM8 can suppress cold‐induced shivering and tachycardia in a whole‐animal mouse model.

Methods

Conscious freely moving mice were injected with the TRPM8 antagonist “compound 5” or TRPV1 agonist dihydrocapsaicin and exposed to cold (10°C). Shivering was measured by a novel method based on electromyography and heart rate was determined by ECG. Core temperature (abdominal) was measured by implanted wireless transponders.

Results

TRPM8 inhibition had no effect on shivering and tachycardia (also confirmed using TRPM8 KO mice). TRPV1 activation led to substantial suppression of the shivering and tachycardic responses to cold, as well as to a large drop in core temperature. Combined treatment led to near complete inhibition of shivering.

Conclusion

TRPV1 activation, but not TRPM8 inhibition, reversibly suppresses cold‐induced shivering and tachycardia. Supported by NINDS NS077413.
Ontogeny of muscle bioenergetic processes in Adélie penguin chicks (Pygoscelis adeliae)
Authors: Fongy Anaïs , Romestaing Caroline , Blanc Coralie , Lacost‐Garanger Nicolas , Raccurt Mireille , Rouanet Jean‐Louis , Duchamp Claude
Published: June 2021

Rapid growth characterizes Adélie penguin chicks reared during the short Antarctic summer but requires a maturation of energetic processes that remains unexplored. The ontogeny of bioenergetics was therefore studied in skeletal muscle of growing chicks during the first month after hatching and compared with adults.

Pectoralis muscle biopsies were surgically obtained at different ages and the respiration of intact mitochondrial networks was measured on permeabilized fibers using carbohydrate or lipidderived substrates. Two fusion proteins involved in mitochondrial network assembly, Mitofusin 2 (Mfn2) and Optic Atrophy 1 (OPA1), were detected by western blots.

Whatever the substrate, fiber respiratory activity markedly increased during chick growth (+198%; p<0.05) and further rose in adults (+40%; p<0.05). Muscle fiber respiratory activity was positively related with Mfn2 and OPA1 relative abundance (r2= 0.89 and 0.79; p < 0.01).

The successive rises in muscle oxidative capacity during penguin life may represent key steps to face both thermal emancipation and growth in childhood and marine life in adulthood. The concurrent rise in mitochondrial fusion protein abundance suggests a remodeling of mitochondrial networks that may contribute to the muscle bioenergetic processes enabling penguins to overcome harsh environmental constraints.

Research was funded by IPEV, CNRS and Lyon University.
Critical closing pressure is the primary modulator of cerebrovascular resistance in older adults
Authors: Robertson Andrew D , Hughson Richard L
Published: June 2021

Rationale

Cerebrovascular resistance (CVR), calculated from mean cerebral blood flow (CBF) and mean arterial blood pressure (ABP), can be further characterized by two independent parameters: critical closing pressure (CrCP) and resistance area product (RAP). These parameters are believed to reflect differences in the metabolic and myogenic control of CVR, respectively. The objective of this study was to assess how CVR, CrCP and RAP interrelate in a healthy aging population and how they adapt to postural change.

Methods

Sixty‐three older adults (36 women, 74 ± 5 years) were categorized in tertiles according to CVR determined from bilateral internal carotid artery blood flow and mean ABP. Apparent CrCP and RAP were estimated from continuous middle cerebral artery blood flow velocity and ABP in supine, sitting and standing postures.

Results

Individuals in the highest tertile for CVR had both higher ABP (P < 0.001) and lower CBF (P < 0.001) than the lowest tertile. Lying supine, CVR was directly related to CrCP (r = 0.43, P < 0.001), but not RAP (P = 0.697). CrCP was reduced (P < 0.001) and RAP was slightly increased (P = 0.010) in upright posture.

Conclusion

High CVR in aging was primarily related to CrCP which might reflect structural changes leading to lower CBF in these individuals. Reduced CrCP with upright posture protects the brain from hypoperfusion during sitting and standing. Funded by CIHR, HSF, NSERC
Circadian properties of the Aplysia R15 neuron: its influence on the L7 motor neuron
Authors: Minton Thomas F. , Watrous James
Published: June 2021

The sea slug Aplysia represents a model organism for the study of neurobiological circuitry, rhythmic motor activity, memory and learning. The R15 is an endogenously bursting neuron that regulates a host of pathways in Aplysia, including respiration and egg‐laying. The R15 activates the L7, which enables egg discharge through the Large Hermaphroditic Duct. The present study examines the circadian properties of the R15 and its influence on the L7 neuronal output. This study uses SNNAP the Simulator for Neural Networks and Action potentials (Ziv et al., 1994) to construct the R15→L7 network. This network is based on models formulated by Butera (1995) and Komendantov (2000). Simulations mimicking abdominal ganglia functions in Aplysia produce changes in the L7 output due to stimulation by the R15. The study shows that changes in circadian patterns of the R15 due to alterations in K+ ion channels and Ca2+‐dependent K+channels markedly impact the function of the L7. Comparison with output from Hodgkin‐Huxley type cells stimulated by the R15 reveals unique properties of the L7 excited by the R15.
Hemodynamic responses during lower body negative pressure and hemorrhage in humans
Authors: Johnson Blair David , van Helmond Noud , Curry Timothy B. , Convertino Victor A. , Joyner Michael J.
Published: June 2021

We tested the hypothesis that hemodynamic responses would be similar during lower body negative pressure (LBNP) and hemorrhage (HEM). We measured central venous pressure (CVP), mean arterial pressure (MAP), and heart rate (HR) in 6 men during LBNP and HEM. The LBNP protocol consisted of 5‐minute stages at 0, ‐15, ‐30, and ‐45 mmHg of pressure. After a 45 minute break, the HEM protocol began and included 5 minutes at baseline and following three stages of 333 mL of HEM (1 L total). HR during LBNP increased from baseline to ‐45 mmHg (61 ± 3 vs. 86 ± 10 bpm, P < 0.01) while HR was unchanged after 1 L HEM (59 ± 4 vs. 66 ± 5 bpm, P = 0.07). HR was higher during LBNP at ‐30 mmHg vs. HEM at 667 mL (71 ± 7 vs. 63 ± 4 bpm, P = 0.03) and at the final stage (P < 0.01). From baseline, MAP tended to be reduced to a similar degree during ‐45 mmHg LBNP (90.9 ± 3.0 vs. 82.2 ± 4.0 mmHg) and 1 L HEM (89.5 ± 2.1 vs. 80.8 ± 4.0 mmHg) (P = 0.06). From baseline, CVP declined similarly during −45 mmHg LBNP (7.9 ± 1.1 vs. 0.1 ± 1.2 mmHg, P < 0.01) vs. 1 L HEM (5.8 ± 1.1 vs. 1.1 ± 1.4 mmHg, P < 0.01). Using the amalgamated r2 across each level of LBNP and HEM, HR (r2 = 0.98, P < 0.01) and CVP were significantly correlated (r2 = 0.98, P < 0.01), but MAP was not (r2 = 0.53, P = 0.27). Although LBNP models the changes in MAP and CVP observed in HEM, differences in the HR response to LBNP and HEM require further exploration. Funding: US Army MRMC Combat Casualty Care Research Program Grant # W81XWH‐11–1‐0823.
Muscle atrophy produced by spinal cord injury (SCI) in rats decreases muscle protein synthesis without altering mTOR kinase activity
Authors: Lang Charles H. , Laufenberg Lacee J , Pruznak Anne , Swartz Emily M. , Holmes Gregory M.
Published: June 2021

SCI produces muscle atrophy and derangements in nutrient homeostasis; however, the mechanisms and temporal patterning of these co‐morbidities are poorly defined. Chronic (≥10 week) SCI has been shown to down‐regulate mTOR/S6K1 signaling in soleus muscle and induce changes in body composition and lipid compartmentalization. We assessed muscle protein synthesis (MPS) and degradation in adult rats using an acute contusion injury model at spinal T3. At 7‐days post‐SCI, lean body and gastrocnemius mass were reduced (15% and 20%, respectively), compared to time‐matched controls. In vivo analysis determined this response was mediated, in part, by a 15% decrease in MPS. Contrary to expectations, phosphorylation of AKT (upstream regulator of mTOR) as well as S6K1 and 4E‐BP1 (downstream mediators of mTOR) was not reduced in muscle after SCI, compared to time‐matched sham controls. SCI tended to increase the muscle‐specific E3 ligases atrogin‐1 and MuRF1, but these changes were not statistically significant. REDD1 was also not increased following SCI. Our data suggest acute SCI in rats produces muscle atrophy primarily by reducing MPS may be mTOR‐independent. (Supported by GM38032 and NS49177)
Genome‐wide association mapping of vasoreactivity in thoracic aorta from inbred mice
Authors: Kim Seung Kyum , Avila Joshua J. , Massett Michael P.
Published: June 2021

There are large strain‐dependent variations in vascular function in mice. However, the genetic factors underlying these variations are undefined. Therefore, the aim of this study was to identify novel putative quantitative trait loci (QTL) regulating vascular function. Vasoreactivity in thoracic aorta from inbred mice was measured and genome wide association mapping (GWA) was performed. Concentration response curves to phenylephrine (PE), potassium chloride (KCl), acetylcholine (ACh), and sodium nitroprusside (SNP) were obtained from aortic rings from male mice (n =4~8/strain) from 18 classical and wild‐derived strains. Maximal responses (MR) and half maximal effective concentrations (EC50) were calculated. GWA was performed for MR and EC50 using an efficient mixed‐model association algorithm (EMMA). Significant strain‐dependent differences were found for both MR and EC50 for each agent, except for MR for SNP. Significant QTL (P<3.79 × 10−7; Bonferroni correction) were identified for MR for PE, ACh, and KCl and EC50 for SNP and KCl on several chromosomes (Chr). Common QTL between MR for ACh and EC50 for SNP were found on Chr 1, 2, and 11. These data indicate that genetic background influences vascular function, and the novel QTL identified in this study provide new targets for investigating the underlying mechanisms for variation in vascular function.

Supported by NIH grant HL085918 to MPM
A dual role for Nucleolin identified by systems analysis of cardiac chromatin remodelers
Authors: Monte Emma , Mouillesseaux Kevin , Chen Haodong , Ren Shuxun , Wang Yibin , Chen Jau‐Nian , Vondriska Thomas M , Franklin Sarah
Published: June 2021

To elucidate mechanisms of chromatin reprogramming during cardiac development and disease, we used a systems approach to identify, screen, and validate changes to the nuclear proteome. Quantitative proteomic analysis of chromatin fractions from mouse hearts in basal, hypertrophy or failing conditions identified 338 proteins whose abundances change. One candidate was Nucleolin (Ncl), which increases 3‐fold in hypertrophy.

Using a functional screen in zebrafish embryos, we characterized a novel role for Ncl to affect cardiac looping and differentiation. 48‐hour embryos express Ncl in the heart, with in situ hybridization demonstrating BMP4 restricted to the atrial/ventricular boundary. After Morpholino knockdown (KD) of Ncl, BMP4 is found throughout the ventricle, suggesting delayed myocyte differentiation. This is accompanied by defects in chamber looping, with 20% of fish failing to loop or reverse looping, a phenotype seen in 29% of fish after over expression; no changes in myocyte size were observed in KD fish. Delayed hearts exhibit a decreased heart rate and increased fractional shortening. Finally, in isolated rat myocytes, loss of Ncl alters transcription of SERCA, ANF, and β‐MHC, whose expression changes are hallmarks of cardiac hypertrophy. This suggests that changes in Ncl levels affect differentiation during development, whereas in disease it may drive the hypertrophic response. NIH funded.
In Vivo Knockdown of TRPV4 Decreases Flow‐Induced Calcium Influx in the Thick Ascending Limb
Authors: Cabral Pablo D. , Garvin Jeffrey L.
Published: June 2021

The thick ascending limb (TAL) plays a critical role in the regulation of salt homeostasis by reabsorbing 30 % of the filtered NaCl. Mechanical stimulation exerted by elevating luminal flow in this segment causes increases in intracellular calcium (Ca(i)). The mechanosensitive Transient Receptor Potential Vanilloid 4 (TRPV4) channel mediates calcium influx in response to luminal flow in other cell types. We hypothesize that flow‐induced calcium influx is mediated by TRPV4 in the TAL. To test our hypothesis we measured Ca(i) using the ratiometric calcium sensitive dye Fura‐ 2 in isolated and perfused TALs. The role of TRPV4 in response to elevations in luminal flow was addressed by targeting the channel using a shRNA against TRPV4. In the absence of luminal flow, activating TRPV4 using the selective agonist GSK1016790A (10 nM) increased Ca(i) levels from 72 ± 16 to 255 ± 50 nM (p<0.04; n=8). We next tested the role of TRPV4 in flow‐induced increases in Ca(i). In non‐transduced control TALs, luminal flow elevated Ca(i) levels by 104 ± 20 nM. However, in TALs transduced with a shRNA‐TRPV4, increasing luminal flow elevated Ca(i) levels only by 56 ± 8 nM (p<0.05, n=9). We conclude that in vivo knockdown of TRPV4 decreases flow‐induced calcium influx in the TAL.

National Heart, Lung and Blood Institute of the NIH to J.L.G (HL 070985; HL 090550 and HL 028982).

American Heart Association to P.D.C (11POST7490010).
CD47 reduces activation‐induced CD4+ T cell death in MOG peptide‐dependent Experimental Autoimmune Encephalomyelitis
Authors: Azcutia Veronica , Bassil Ribal , Khoury Samia J. , Elyaman Wassim , Luscinskas Francis W.
Published: June 2021

CD47 is involved in immune cell recruitment and adaptive immune responses. We have recently reported CD47 plays an important role in CD4 T cell recruitment to sites of inflammation in vivo and in vitro. Here we have examined the role of CD47 in a murine experimental autoimmune encephalomyelitis (EAE) model. Surprisingly, immunization of CD47−/− mice with myelin oligodendrocyte glycoprotein (MOG)35–55 peptide does not induce EAE or CNS inflammation. In contrast, transfer of activated, MOG‐specific TCR transgenic WT CD4 T cells caused disease in WT and CD47−/− mice, suggesting a defect in the immune cell activation. Accordingly, eight days post MOG immunization, the number of CD4+ T cells in spleens and draining lymph nodes was significantly reduced in CD47−/− vs WT mice (43 and 30% reduction, respectively). A MOG‐dependent proliferation assay using CD4 T cells and dendritic cells revealed the defect lay in CD4 T cells from CD47−/− mice (84% reduction). Unexpectedly, we detected greater CD4 T cell activation by MOG immunization in CD47−/− vs WT mice, however, CD47−/− CD4 T cells showed much greater apoptosis in vivo (Annexin‐V and TUNEL staining) and in vitro (2.3 fold increase in Annexin‐V/7‐AAD staining). Our results suggest that CD47 contributes to CD4 T cell recruitment and resistance to self‐peptide activation‐induced cell death in this EAE model. This work was supported by NIH P01HL03628 and AHA 11POST7730055.
Bone marrow cells can be converted into cardiac competent progenitors via inhibition of G9a Histone Methyltransferase G9a
Authors: Yang Jinpu , Eisenberg carol A , Eisenberg leonard M
Published: June 2021

Given that the optimal treatment for the damaged heart is to replace dysfunctional myocytes, great effort has been made to develop stem cell therapies for regenerating cardiomyocytes (CM). We demonstrated previously that bone marrow (BM) have a capacity, albeit limited, to convert into CM. To improve the yields of CM from BM, we screened various molecules that were reported to assist the induction of induced pluripotent stem cells (iPSC) from somatic cells, for their effect in enhancing BM cardiopotency. From this experimentation, we identified BIX01294, a selective inhibitor of G9a histone methyltransferase (HMTase), as a candidate for reprograming BM cells to a cardiopotent phenotype, as indicated by the upregulation of precardiac genes (Brachyury, Mesp‐1 and Isl‐1). Knockdown of G9a HMTase by shRNA provided supporting evidence that inhibiting this enzyme promotes the conversion of BM cells to cardiopotent progenitors. Moreover, in response to the cardiac inducer Wnt11, BM cells pretreated with BIX01294 had much more profound expression of myocardial genes and proteins, including Nkx2.5, Gata4, Hand1, Hand2, Tbx5, myocardin, α‐actinin, and titin. In summary, these data indicate that promoting specific epigenetic modification by pharmacological inhibitor BIX01294 can assist the conversion of BM cells into cardiopotent progenitor cells that may have utility for in vivo cardiac repair and regeneration.

Grant Funding Source: NIH NHLBI HL086815
Impact of human pluripotent stem cell‐derived extracellular matrix proteins on cardiac cell fate decision
Authors: Holeiter Monika , Bluguermann Carolina , Evseenko Denis , Crooks Gay , Schenke‐Layland Katja
Published: June 2021

Incomplete understanding of the various factors that drive cardiac cell fate decisions limits the development of clinically successful pluripotent cell‐based strategies for the diseased heart. The objective of this study was to identify crucial ECM proteins that drive cardiac differentiation, presuming that a healthy developing cardiac ECM may help regenerate damaged cardiac tissue by providing a suitable microenvironment for cell replacement strategies. We employed a modified cardiac differentiation protocol, which allowed the robust and reproducible generation of spontaneously beating embryoid bodies (EBs) (85% ± 17.6%) from human embryonic stem cells (hESCs). EB‐derived cardiomyocytes were characterized using immunohistochemistry (IHC) and flow cytometry (cardiac troponin T (cTnT) or sarcomeric myosin), as well as quantitative real‐time PCR (qPCR). Monitoring of cardiac‐specific ECM by IHC and qPCR, allowed the identification of an increased expression pattern of decorin and nidogen‐1 during the differentiation of pluripotent stem cells towards the cardiovascular lineage. We hypothesize that identifying cardiac‐specific ECM proteins secreted during cardiogenesis will lead towards the development of biomaterials that may allow regeneration of the ischemic heart.

Grant Funding Source: Fraunhofer Gesellschaft
Dynamic Formation of the Chick Sympathetic Ganglia
Authors: Kulesa Paul , Kasemeier‐Kulesa Jennifer C. , Lefcort Frances
Published: June 2021

The sympathetic nervous system (SNS) plays a vital role in maintaining homeostasis and is derived from the embryonic neural crest. Trunk neural crest cells migrate as individuals along a ventral pathway and aggregate into primary sympathetic ganglia (SG) that form as discrete structures along the vertebrate axis. Within hours of formation, sympathetic precursors migrate dorsally and form the permanent, secondary chain of SG.

The cellular and molecular mechanisms that mediate dorsal migration and formation of the secondary SG are largely unknown. This is due to the ventral, less accessible location of this morphogenetic event deep within the embryo. Using transverse slice culture and confocal time‐lapse microscopy, we detail the events involved in chick secondary SG formation. We find that the primary SG move as a cohesive cluster during their dorsal migration. SG cells display extensive cell contacts among neighbors and project long filopodial extensions in the direction of travel towards the forming spinal nerve. Extensions from the spinal nerve interact with dorsally migrating SG cells in an exciting interplay of cell contact to position the secondary SG. I will discuss these cell behaviors and emerging molecular studies aimed at identifying the factors that drive proper SG positioning and development.
The history of medical histology teaching: where have we come from and where are we going?
Authors: Bloodgood Robert Alan
Published: June 2021

As we reach the 125th anniversary of the AAA, it is instructive to look back over the history of histology teaching and how and why it has evolved. At the 1st AAA meeting in 1888, the distinguished Philadelphia Anatomist and Polymath Joseph Leidy was elected the society's first President. Among his many talents (he was referred to by his biographer as “The last Man Who Knew Everything”), Leidy was an accomplished microscopist and both taught histology at the University of Pennsylvania School of Medicine and published new histological findings. Further, he was probably the 1st person in the United States to ever help solve a murder by using the microscope! We will consider the various factors that have changed the way we utilize images and the manner in which we teach histology in medical schools since the founding of the Society. These include changes in technology, changes in the missions of medical schools and academic medical centers, changes in the source of financing for and manpower utilization in medical schools, changes in educational theory and changes in medical practice. As we embrace technology (perhaps sometimes for very practical reasons not necessarily intended to improve the quality of education), do we risk taking the medical educator out of medical education and, in so doing, what do we lose?
Sensory neurons accelerate reepithelialization through Substance P release in an innervated tissue‐engineered model of skin wound healing.
Authors: Blais Mathieu , Mottier Lorène , Cadau Sébastien , Bareil Rémi Parenteau‐ , Berthod François
Published: June 2021

The keratinocytes are responsible for the restoration of the epidermal barrier through reepithelialization during the wound healing process in humans. The influence of sensory neurons on this mechanism is poorly understood. We tested whether sensory neurons influence reepithelialization via a secretion of the neuropeptide substance P (SP). We developed a new tissueengineered model of skin wound healing. It consists of a perforated tissue‐engineered skin made of keratinocytes expressing GFP and that was stacked on a dermis to reconstitute the wound bed. The dermal construct is endothelialized by human endothelial cells and innervated or not by mouse sensory neurons. The migration of keratinocytes was imaged and quantified with GFP fluorescence. Sensory neurons produce SP in the construct as shown with ELISA and immunofluorescence analysis. Keratinocytes were found to express the NK1 cell receptor for SP in the reconstructed epidermis. The rate of reephithelialization was increased in presence of sensory neurons and SP was shown to contribute to this effect using antagonist to NK1 and recombinant SP instead of neurons. We conclude that this new model is promising for the study of the influence of the peripheral nervous system on reepithelialization.

Grant Funding Source: N/A
Intakes of total and plant protein are associated with greater muscle strength: The Framingham Osteoporosis Study
Authors: McLean Robert R , Hannan Marian T , Kiel Douglas P , Casey Virginia , Mangano Kelsey M , Sahni Shivani
Published: June 2021

Objective

To determine the relation of dietary protein with quadriceps muscle strength in Framingham Offspring participants.

Methods

Multivariable regression assessed protein (g/d, from FFQ 1995–98) with isometric quadriceps strength measured by hand‐held dynamometer (kg, max of 2 trials) in 2,674 men & women. Least squares‐adjusted mean strength was calculated for quartiles of energy‐adjusted protein (residual method) and linear trend tested. Model 1 assessed total protein (TP) and model 2 assessed animal (AP) and plant (PP) proteins.

Results

Mean age 60 ± 9y. Protein intakes (g/d) were TP: 78±27, AP: 54±22; PP: 24±9. Participants in high quartiles of TP (Q3–Q4) and PP (Q4) had higher quadriceps strength compared to those in Q1 (Table). No significant associations were seen for AP intake. Similar results were observed with protein as a continuous variable.

Conclusions

TP & PP intakes, but not AP were positively associated with quadriceps strength; consistent with data showing that alkaline diets may favor the preservation of muscle mass in older adults.

Funding source: NIH AR # 053205; AR/AG41398, Framingham Heart Study (N01‐HC‐25195) & General Mills Bell Institute of Health and Nutrition
Endothelial GATA6 deficiency promotes pulmonary arterial hypertension (PAH) through ER stress‐mediated CHOP upregulation
Authors: Chrobak Izabela Maria , Ghatnekar Angela , Lenna Stefania , van Deuren Rosanne , Radstake Timothy , Feghali‐Bostwick Carol , Trojanowska Maria
Published: June 2021

PAH is characterized by pulmonary vasculopathy, pulmonary artery pressure and RV failure. Previous studies have implicated endoplasmic reticulum (ER) stress in several disorders, including atherosclerosis, but its involvement in PAH has not yet been investigated. GATA6 is expressed in quiescent vasculature, but is lost in vascular injury. Our goal was to investigate the role of endothelial GATA6 in mediating ER stress in PAH.

Gata6 flox/flox mice were bred with mice expressing Cre under the ECs‐specific VE‐cad promoter (Gata6 CKO).

Gata6 CKO mice developed PAH and had severe changes in hemodynamics under hypoxia. Furthermore, loss of GATA6 resulted in worsened vascular remodeling and RV hypertrophy in hypoxia. The ER stress‐related markers BiP, PERK, ATF4 and XBP were moderately upregulated, whereas pro‐apoptotic marker CHOP was significantly upregulated in Gata6CKO mice. Furthermore, upregulation of BiP protein was observed in Gata6CKO lungs by immunohistochemistry. Consistent with in vivo observations, depletion of GATA6 in HPAECs via siRNA resulted in upregulation of ER stress mediators including BiP, ATF4 and CHOP.

Our findings suggest that GATA6 deficiency in endothelial cells leads to development of PAH, in part via upregulation of ER stress/CHOP pathway.

This study was supported by NIH grant RO1 AR42334 and Postdoctoral Fellowships NIH training grant T32 AR 050958.
Surfactant activity and mobilization in minced saline extracts of neonatal brain, heart, kidney, liver, and lung
Authors: Shanklin Douglas Radford
Published: June 2021

Minced saline tissue extracts yield minimum values higher than airspace washings, attributed to different proportions of saturated fatty acids and phosphatidylcholine, with typical hysteresis in both. Saline minced extracts from newborn autopsy tissues (Kimray Greenfield surfactometer) follow the formation of lung lesions; 16 newborns up to 90 hrs had a progressive but counter intuitive decline in lung minimum values, suggesting enhanced synthesis without therapy or recruitment of surfactant [Regression equation: minimum (dynes/cm) = −0.1936 (survival hrs) + 23.7040]. No difference was seen by gestational time (22–40 wks), as shown by Esterly (Am.J.Clin.Path. 46:649, 1966), a finding against surfactant deficiency due to prematurity per se. Lesser declines in the minimum was found in extracts of myocardium (43.1% of lung), kidney (17.8%), liver (16.5%), while the minimum worsened in extracts from cerebrum (+7.0%), the largest pool of phospholipids of the five tissues. This sequence suggests possible mobilization of surface active lipids during the first four days after birth, despite respiratory or other disorders. Twenty stillborns had similar results by gestational age; mean minimums for stillborn lung and liver were not significantly different from mean newborn values (lung, t = 0.392, p = 0.696; liver, t = 1.019, p = 0.315). Thus, newborn surfactant dynamics are systemic.

Support: The Rhad Trust
In‐vivo dynamic and hyperspectral microscopy
Authors: Hillman Elizabeth M. C.
Published: June 2021

Microscopy techniques have advanced our understanding of healthy and diseased tissues for over 100 years. Over the past 20 years, techniques for in‐vivo microscopy have advanced, allowing examination of cells and tissues in situ, within the living body. While imaging in‐vivo presents many technical challenges, it also brings rewards. Imaging living tissues allows their function and physiology to be studied in real time, particularly their responses to stimulation or other interventions or therapies. These possibilities place new requirements on microscopy techniques to be able to capture dynamic events, in 3D within living tissues. Available contrast must also be considered. Substances suitable for specific labeling in‐vivo can be used, or imaging can visualize transfected cells expressing fluorescent proteins, some of which can report cellular function themselves. Additional contrast is available from intrinsic absorbers and fluorophores such as hemoglobin, NADH and FAD, whose dynamics can allow tissue metabolism to be directly visualized. Separating such sources of in‐vivo contrast, and moreover capturing multiple forms of contrast in parallel during dynamic cellular events can be achieved through hyperspectral microscopy. This talk will describe techniques optimized for in‐vivo microscopy, and will provide examples of the kinds of processes that can be visualized in the living brain and skin.
Transitioning to an integrated curriculum: Challenges, opportunities and student performance in gross anatomy
Authors: Hoagland Todd M
Published: June 2021

A Pilot Integrated Curriculum (PIC) for 28 of 204 students was taught systems‐based in a modular format. The modules were: Musculoskeletal & Skin; Cardiovascular, Respiratory, & Renal; GI, Nutrition, & Metabolism; Reproductive Medicine; Endocrine; Brain, Mind & Behavior; Hematology, Lymphatic & Neoplasia; Infections & Inflammation, and Symptoms‐Based Presentations. This was a radical change from the discipline‐based traditional curriculum. The PIC students have taken the USMLE Step 1, NBME shelf, and departmental exams, and are now in M3 clinical clerkships. Some factors that contribute to successful integration are: clear learning objectives, placing content in a context where its relevance was apparent, and seeking and responding to student feedback. Some challenges to integrating content are: a heavy reliance on clinical faculty for integration, coordinating activities of numerous basic scientists and clinicians from many different departments, and preventing the erosion of faculty morale. The presentation will compare students’ performances in the PIC versus traditional curriculum on numerous summative examinations, and use narrative comments by students and faculty members to highlight important outcomes. Students routinely raved about content when it was integrated well across disciplines, but integrating content well is challenging for many basic scientists and clinicians.
Roles for pericytes at the neurovascular unit
Authors: Daneman Richard
Published: June 2021

The blood vessels of the central nervous system (CNS) form a barrier that is crucial for proper brain function and to protect the CNS from injury and disease. Determining the mechanisms regulating BBB function may prove vital to develop therapeutics to restore the BBB to prevent CNS damage during neurological disease. We have used microarray analysis to compare the gene expression of endothelial cells purified from the CNS with endothelial cells purified from non‐neural tissue, and thus have generated a comprehensive resource of transcripts that are enriched in the BBB forming endothelial cells of the CNS. Through this comparison we have identified novel tight junction proteins, transporters, metabolic enzymes, signaling components, and unknown transcripts whose expression is enriched in CNS endothelial cells. This analysis has led to the identification that neural stem cell‐derived Wnt/beta‐catenin signaling is required for CNS angiogenesis, but not angiogenesis in non‐neural tissue, and also induces BBB‐specific gene expression. Here we further analyze this transcriptome to identify novel regulators of BBB formation and function.
mRNA surveillance is driven by translation
Authors: Green Rachel , Guydosh Nicholas
Published: June 2021

There are several mRNA surveillance pathways in eukaryotes that moderate the effects of natural errors in the cell and more broadly regulate gene expression. We have recently defined biochemical parameters of the no‐go decay quality control system using our previously developed in vitro reconstituted yeast translation system. In these studies, we have shown that two factors implicated in no‐go decay (NGD) and non‐stop decay (NSD), Dom34 and Hbs1, promote subunit dissociation and peptidyl‐tRNA drop‐off on the ribosome to initiate recycling events that eventually lead to mRNA decay. Of particular interest is that these factors (Dom34 and Hbs1) appear to identify stalled ribosome complexes that are associated with 3’ truncated mRNAs, suggesting a biochemical outcome for a likely in vivo consequence of stalling during translation (endonucleolytic cleavage of the mRNA). Current efforts focus on a broad analysis of the in vivo targets of mRNA surveillance (including NGD, NSD and NMD) using a series of reporter constructs and genome wide ribosome profiling.
Cell Biology of Neutral Lipid Storage
Authors: Walther Tobias
Published: June 2021

Organisms buffer fluctuations in energy availability by storing metabolic energy. Neutral lipids, such as triacylglycerols and sterol esters, provide an efficient form to store metabolic energy and membrane precursors. Cells store neutral lipids in cytosolic Lipid Droplets (LDs). LDs function at critical points of cellular physiology: Not surprisingly therefore, LDs are involved in many common diseases, such as metabolic syndrome, fatty liver disease, atherosclerosis and obesity. Despite their almost universal presence and links to common human pathologies, many basic questions about LDs persist. LDs thus provide both great challenges and opportunities for cell biology. Within this field, we specifically address how lipid droplets are built, how they grow, how they contribute to the organization of biochemical pathways and how lipids get stored and utilized there. Building on cell biological discoveries, we connect mechanistic studies of LDs with their important functions in disease.
Holliday Junction Resolvases: the Good, the Bad and the Ugly
Authors: West Stephen
Published: June 2021

In simple organisms, Holliday junctions (HJs) that arise during recombination and the recombinational repair of DNA are resolved by a junction‐specific endonuclease activity. For example, in E. coli, the RuvC protein specifically recognises and binds HJs, and then promotes their cleavage by the introduction of symmetrically‐related nicks across the junction point. The resulting nicked duplexes can then be religated.

In contrast, mitotic eukaryotic cells appear to have evolved a rather different mechanism of resolution, because in humans the removal of HJs is preferentially mediated by the BTR complex (BLM‐TopoIIIα‐ RMI1–RMI2), which combines DNA helicase and topoisomerase activities to bring about HJ ‘dissolution’. The benefit of this mechanism of HJ processing is that recombination events that link homologous chromosomes are guaranteed to be resolved to form non‐crossovers, thereby avoiding crossovers and the potential for loss of heterozygosity (LOH) of tumour suppressor genes ‐ a hallmark feature of cancer cells.

Given the importance of avoiding crossovers, it is perhaps surprising that mitotic cells encode three junction‐specific nucleases that can resolve HJs to form crossovers. In humans, these are MUS81‐EME1, SLX1‐SLX4 and GEN1. How these nucleases are controlled, in order to avoid crossover formation, has revealed unexpected insights into mechanisms of Holliday junction processing.
A prospective study of global DNA methylation and development of adiposity in Colombian schoolchildren
Authors: Perng Wei , Mora‐Plazas Mercedes , Rozek Laura S. , Marin Constanza , Baylin Ana , Villamor Eduardo
Published: June 2021

Objective

To examine associations of global DNA methylation with changes in adiposity in a longitudinal study of school‐age children from Bogotá, Colombia.

Methods

We quantified methylation of LINE‐1 elements from peripheral leukocytes of 553 children aged 5–12 y at baseline using pyrosequencing technology (Qiagen). Anthropometric characteristics were measured periodically for a median of 30 months. We estimated mean change in 3 age‐standardized indicators of adiposity: body mass index (BMI) Z score (BMIZ), waist circumference Z score (WCZ), and triceps‐to‐subscapular skinfold thickness ratio Z score (SKFZ) according to quartiles of LINE‐1 methylation using multivariable mixed effects linear regression.

Results

There were inverse, non‐linear relations of DNA methylation with BMIZ and SKFZ change in boys. After adjustment for baseline age and socioeconomic status, boys in the lowest quartile of LINE‐1 methylation experienced annual gains in BMIZ and SKFZ that were 0.06 Z/y (P=0.04) and 0.07 Z/y (P=0.03), respectively, higher than those in the upper three quartiles. There was an inverse, monotonic relation of LINE‐1 methylation with annual change in WCZ (P trend=0.02). DNA methylation was not related to development of adiposity during follow‐up among girls.

Conclusions

Global DNA methylation was inversely related to development of central adiposity in boys.

Grant Funding Source: This study was funded by the Robert Wood Johnson Foundation Research Project Awards. The Bogotá School Children Cohort is currently sponsored by the ASISA Research Fund at the University of Michigan.
Using a culturally‐tailored sugar screening tool to give dietary recommendations for reducing sugar intake in Mexican‐American adults
Authors: Chavez Adrian , Parra Andrea E. , Robles Michelle , Flores Lorena R. , Leander Lauren , Vega‐López Sonia
Published: June 2021

To examine the feasibility of using a culturally‐tailored sugar screening tool for reducing sugar intake, a sugar screening questionnaire was administered to twenty‐four healthy Mexican‐American adults (10 M, 14 F; Age = 39.8±11.1 y; BMI = 32.1±1.5 kg/m2) to assess the primary contributors of sugar to their diet from which personalized dietary recommendations were given. Dietary data (3‐day food record) was assessed at baseline and one month post intervention. Relative to baseline, participants reported an 11% reduction in energy intake (2100 vs. 1862 kcal/d; p<0.05) associated with a 24% reduction in total fat intake (88 vs. 67 g/d; p<0.005). There was a non‐significant reduction in mean total‐ and added‐sugar intake (13% and 24%, respectively; n.s.), mainly driven by the 58% of the sample who reduced their sugar consumption (−51±12 g/d). Modest correlations between sugar intake assessed by the screening tool and by 3 day food record at baseline (r=0.614; p<0.005) and follow‐up (r=0.633; p<0.05) suggest that the sugar screening tool was effective at assessing sugar intake. Data from the sugar screening tool revealed a 51% decrease (28.4 vs. 14.0 g/day; p<0.05) in sugar from sweetened beverages. While no reductions in total sugar intake were observed, the sugar screening tool was effective for assessing sugar and for reducing the consumption of sugar sweetened beverages in a sample of healthy Mexican‐Americans.
γ‐Tocopherol additionally improves vascular endothelial function following smoking cessation by decreasing pro‐inflammatory responses
Authors: Mah Eunice , Ballard Kevin D , Pei Ruisong , Guo Yi , Volek Jeff S , Bruno Richard S
Published: June 2021

Oxidative stress and inflammation that persist following smoking cessation limits the restoration of vascular endothelial function (VEF). We hypothesized that smoking cessation with γ‐tocopherol (γ‐T)‐rich supplementation would decrease oxidative stress and pro‐inflammatory responses and improve VEF beyond that of smoking cessation alone. A randomized, double‐blind, placebo‐controlled study was conducted in otherwise healthy smokers (≥10 cigarettes/d) who quit smoking for 7 d with placebo (n = 14) or γ‐T‐rich supplementation (n = 16; 500 mg γ‐T/d). Brachial artery flow‐mediated dilation (FMD), plasma cotinine, vitamin E, malondialdehyde (MDA), and pro‐inflammatory mediators were measured before and after 7 d of smoking cessation. Smoking cessation regardless of supplementation similarly decreased plasma cotinine whereas plasma γ‐T increased by 7‐fold (P<0.05) only in those receiving γ‐T‐rich supplements. Smoking cessation with γ‐T‐rich supplementation increased FMD responses beyond that of smoking cessation alone (P<0.05). Although MDA decreased similarly in both groups, myeloperoxidase and TNF‐α decreased only in those receiving γ‐T‐rich supplementation. These findings support that improvements in γ‐T status additionally improve VEF during smoking cessation likely by decreasing pro‐inflammatory responses. Funded by CT Department of Public Health.

Grant Funding Source: Connecticut Department of Public Health
Diet‐induced obese mice exhibit heightened lung inflammatory and cross‐reactive CD8 T cell responses during a secondary 2009 pandemic H1N1 influenza infection
Authors: Milner J Justin , Sheridan Patricia A , Karlsson Erik A , Schultz‐Cherry Stacey , Shi Qing , Beck Melinda A
Published: June 2021

Obese individuals were at greater risk for hospitalization and death following infection with the 2009 pandemic H1N1 influenza virus (pH1N1). Although cross‐reactive memory T cells can limit pH1N1 death and disease severity, we have previously shown obese mice and humans exhibit impaired memory T cell function. To determine if obesity results in greater pH1N1 morbidity as a consequence of impaired cross‐reactive T cell defenses, diet‐induced obese and lean, control mice were infected with a sublethal dose of influenza PR8. After 5 wk, the mice were challenged with a lethal dose of heterologous pH1N1. Despite a lack of differences in mortality, obese mice lost more weight and exhibited greater lung viral burden, immune cell infiltration, pathology and reduced lung integrity during the secondary challenge. Consistent with the elevated lung inflammatory responses, obese mice had a greater number of cytotoxic effector memory CD8+ T cells in the lungs. To investigate a potential mechanism for the excess inflammatory and pathological responses in the lungs of obese mice, we assessed the distribution of anti‐inflammatory regulatory T cells (Tregs). Although obese mice had twice has many lung Tregs compared with lean mice, Tregs isolated from obese were 40% less functional. Taken together, drastic impairments in Treg function may contribute to excessive inflammation and greater pH1N1 infection severity in the obese.

Grant Funding Source: NORK DK56350
Curcumin modulation of atherosclerosis and hepatosteatosis in LDLr−/− mice
Authors: Hasan Syeda Tahira , Zingg Jean‐Marc , Noble Timothy , Kwan Paul , Smith Donald , Meydani Mohsen
Published: June 2021

Limited animal studies reported that curcumin (Cur), a bioactive component of turmeric spice, suppresses atherosclerosis, an inflammatory disease of arteries, but the mechanism for these effects is largely unknown. LDLr−/ − mice were fed high fat (HF) diet supplemented with increasing Cur doses (500, 1,000, 1,500 mg/kg diet) for 16 wks. Cur reduced BW and fat gain although fecal fat excretion was less than control's suggesting increased catabolism. Medium dose Cur diet (1,000 mg/kg) significantly reduced aortic fatty streaks and suppressed IL‐6 and MCP‐1 expression in aortas, but high dose diet (1,500 mg/kg) had adverse effect on these parameters and increased plasma levels of several inflammatory cytokines including IL‐6, IL‐10, IL‐12. This U‐shaped trend was also present when aortic roots were examined for fatty lesions, fibrotic deposits, FABP‐4/aP2 and VCAM‐1 expression. Of note, Cur at high dose suppressed hepatosteatosis, reduced fibrotic tissue, and preserved liver glycogen levels. While complex mechanisms are involved in Cur suppression of HF diet‐induced atherosclerosis and obesity, Cur suppression of aP2 and VCAM‐1 expression in aortic root lesions and aP2 expression in macrophages along with reduction of inflammatory cytokines provide an insight to the potential mechanism by which Cur suppresses atherogenesis and obesity. NIFA/USDA grant #2010–65200‐20395 &USDA contract #58–1950‐0–014.
COCOA CONSUMPTION DOSE‐DEPENDENTLY IMPROVES FLOW‐MEDIATED DILATION AND ARTERIAL STIFFNESS IN HEALTHY SUBJECTS
Authors: Grassi Davide , Desideri Giovambattista , Necozione Stefano , Di Giosia Paolo , Cheli Paola , Barnabei Remo , Allegaert Leen , Bernaert Herwig , Ferri Claudio
Published: June 2021

To investigate the effects of different doses of cocoa on endothelial function and arterial stiffness.

According to a randomized, double‐blind, controlled, cross‐over design, 20 healthy volunteers were assigned to receive either five treatments with daily intake of 10 g cocoa (0, 80, 200, 500 and 800 mg cocoa flavonoids/day) in five periods lasting 1 week each.

Cocoa dose‐dependently increased flow‐mediated dilation (FMD) from 6.2% (control) to 7.3, 7.6, 8.1 and 8.2% after the different flavonoid doses, respectively (p < 0.0001). Compared with control, even 80 mg cocoa flavonoids/day increased FMD (p < 0.0001). The change in FMD after 800 mg/day was not only significant compared with control (p < 0.0001) but also with 80 mg/day (p = 0.0003) and 200 mg/day (p = 0.05). Compared with control, carotid–femoral artery pulse wave velocity (PWV) dose‐dependently ( 0 mg vs. 200 mg: p = 0.0008; 0 mg vs. 500 mg: p < 0.0001; 0 mg vs. 800 mg: p < 0.0001) decreased.

Our study showed for the first time that cocoa dose‐dependently improved FMD and decreased PWV. Our findings are clinically relevant, suggesting cocoa, with very low calorie intake, might be reasonably incorporated into a dietary approach representing a consistent tool in cardiovascular prevention. Starting from our findings, the European Food Safety Authority claimed a relationship between cocoa flavanols and endothelial‐dependent vasodilation.