bluuebunny/crossref_metadata_2025 huggingface dataset:
Adaptation of the Heart to High‐Dietary Fat: Rapid Inhibition Of Pyruvate Dehydrogenase
Authors: Crewe Clair Loraine , Kinter Michael , Szweda Luke
Published: June 2021

Cardiac function depends on the ability to switch between fatty acid and glucose oxidation for energy production in response to changes in substrate availability and energetic stress. In obese and diabetic individuals, increased reliance on fatty acids and reduced metabolic flexibility are thought to contribute to the development of cardiovascular disease. Mechanisms by which cardiac mitochondria contribute to diet‐induced metabolic inflexibility were investigated. Mice were fed a high fat or control diet for varying durations. Cardiac mitochondria isolated from mice fed a high fat diet displayed a diminished ability to utilize the glycolytically derived substrate pyruvate. This was the consequence of pyruvate dehydrogenase (PDH) inhibition through a selective increase in PDH kinase 4 expression. This response was rapid, occurring within 1 d on the high fat diet and persisted for at least 20 wks. Strikingly, PDK4 content was rapidly diminished and PDH inhibition relieved upon removal of the mice from the high fat diet. While PDH was activated by in vivo epinephrine stimulation following high fat feeding, the enzyme did not reach the same level of activation as the control. The rapid nature of this response suggests that mechanisms are in place to coordinately regulate cardiac glucose and fatty acid utilization, but may affect the ability of the heart to respond to physiological stress.
AMENDMENT AND VENTRICULAR HYPERTROPHY IN CALCIUM HOMEOSTASIS AS A MECHANISM OF CARDIAC DYSFUNCTION IN THE EVOLUTION OF HYPERTENSION AND AGING
Authors: Pereira Elenize Jamas , Leopoldo Ana Paula Lima , Matsubara Beatriz Bojikian , Matsubara Luiz Shiguero
Published: June 2021

INTRODUCTION

The arterial hypertrophy, and aging are factors that promote ventricular dysfunction and consequently heart failure.

OBJECTIVE

Evaluate cardiac function in the presence of hypertension and aging and their interaction with hypertrophy and mRNA expression of regulatory proteins of Calcium homeostasis.

MATERIAL AND METHODS

We studied 60 spontaneously hypertensive rats (SHR) and 50 non‐hypertensive rats (WKY) were divided into groups of 30, 45, 60 and 90 weeks of age. Four animals from each group were used only for the analysis of RNA by RT‐PCR.

Ventricular function (RPVs and RPVd) was studied in isolated heart Langendorff technique. A curved sectional myocyte (Area cel) and collagen volume fraction (CVF) was measured in slides stained with HE and Sirius red Picro respectively.

The variables were analyzed by 2‐way ANOVA considering factors strain (SHR, WKY) and age. The association between age and the variables was analyzed by Spearman correlation test The significance level was p <005.

RESULTS

There was a statistically significant difference between SHR and WKY in the studied variables except for Log PVdiast, phospholamban and Ryanodine

Significant correlations were observed between age and SBP (SHR r = 0.53, p <0.012, FVC (r WKY = 0.55, p = 0.001).

Area Cel (SHR r = 0.70, p = 0.001, r WKY = 0.543, p = 0.001), second Serca (WKY r = 0.73, p = 0.008 and phospholamban (WKY r = 0.60 p = 0, 04).

CONCLUSION

In aging there is increased cell area, independent of hypertension and decreased systolic function and decreased phospholamban and SERCA2a mRNA in animals, not hypertensive.

The mechanical stress secondary to HA alters calcium homeostasis by promoting instead hypertrophy of ventricular contractile function.
Perivascular adipose tissue contributes to large elastic artery stiffness with aging and is associated with greater superoxide bioavailability
Authors: Fleenor Bradley Stephen , Eng Jason S , Pham Bryant T , Kloor Jackson D , Seals Douglas R
Published: June 2021

We tested the hypothesis that perivascular adipose tissue (PVAT) contributes to age‐related large elastic artery stiffening and is associated with greater superoxide production. PVAT from young (Y, 6 mo, n=5) and old (O, 27 mo, n=5) donor C57BL6/N mice was transplanted directly onto the abdominal aorta of Y recipient (6 mo) mice for 8 weeks. Y recipient mice transplanted with PVAT from O compared with Y donors had greater arterial stiffness as assessed by aortic pulse wave velocity (409 ± 7 vs. 342 ± 8 cm/s, P < 0.05) and ex vivo intrinsic mechanical stiffness (3197 ± 647 vs. 1889 ± 520 kPa, P < 0.05). Systolic (109 ± 5 vs. 111 ± 2 mmHg), diastolic (75 ± 5 vs. 82 ± 2 mmHg) and mean (86 ± 5 vs. 91 ± 2 mmHg) blood pressure did not differ between groups (n=3–4). Additional aortic segments from Y and O mice with (+) or without (−) PVAT (n=5–6) were cultured for 72 hours followed by intrinsic mechanical testing. Aortic segments from O+PVAT (3947 ± 276 kPa, P <0.05) had greater stiffness compared with Y+PVAT, Y−PVAT and O‐PVAT (2437 ± 226, 1768 ± 132 and 2668 ± 404 kPa, respectively); O‐PVAT had greater mechanical stiffening than Y−PVAT (P < 0.05). PVAT superoxide production was greater in O vs. Y (13835 ± 2322 vs. 6657 ± 1720 AU, P < 0.05, n=5–6). Collectively, these data demonstrate PVAT contributes to large artery stiffening with aging and is associated with increased superoxide bioavailability.
Aging downregulates MRPs and increases cardiac doxorubicin accumulation
Authors: Gibson Noah M , Pfannenstiel Keith , Quinn Colin J , Hydock David S , Hayward Reid
Published: June 2021

Doxorubicin (DOX) is a common antineoplastic agent used to treat cancer patients of all ages. The primary side effect of DOX treatment is a dose‐dependent cardiotoxicity, which is developed in a more delayed manner in children. Multidrug resistant protein‐1, ‐2, and ‐7 (MRP‐1, ‐2, ‐7) are known to extrude DOX and may factor into the degree of cardiac DOX accumulation. The purpose of this study was to examine age‐related differences in cardiac MRP expression and DOX accumulation. Female Sprague‐Dawley rats were randomly selected to receive a 15 mg DOX/kg body weight (i.p.) at 4, 8, 12, 16, 20 or 24 weeks of age. Animals were sacrificed 24 hours following injection and hearts were excised, flushed of blood, and left ventricles (LV) were isolated. High performance liquid chromatography was utilized to quantify DOX and Western blotting to analyze MRP expression. DOX accumulation was lowest in 4‐week (675±183 ng DOX/g LV) and 8‐week old animals (724±247 ng DOX/g LV) and was significantly increased (p<0.05) at 12‐weeks (992±304 ng DOX/g LV) and 16‐weeks (1068±348 ng DOX/g LV) as well as 20‐weeks (1440±226 ng DOX/g LV) and 24‐weeks (1321±247 ng DOX/g LV). A significant downregulation (p<0.05) of MRP‐2 (3‐fold) and MRP‐7 (4‐fold) expression was seen with increasing age while no differences in MRP‐1 expression were observed. These data suggest that MRP‐2 and MRP‐7 expression may play a role with increased DOX accumulation with age.
Effects of GLP‐1 receptor agonist on Ca2+ handling in coronary smooth muscle cells from metabolic syndrome Ossabaw swine with coronary artery disease
Authors: Lee McKenney Mikaela , Suh Daniel , Martin John , Alloosh Mouhamad , Schultz Kyle , Sturek Michael
Published: June 2021

Chronic effects of glucagon‐like peptide (GLP‐1) receptor agonists were studied in Ossabaw swine with metabolic syndrome (MetS). MetS was induced by hypercaloric atherogenic diet for 6 months. Subcutaneous injections were given twice daily for 6 months after induction of MetS. Consistent with clinical effects, food consumption and weight gain were attenuated. MetS increases coronary artery disease (CAD) and coronary smooth muscle (CSM) Ca2+ dysfunction. CSM cells were isolated enzymatically from the coronary arteries and Ca2+ was digitally imaged with fluorescent fura‐2. In normal physiological salt solution we released sarcoplasmic reticulum (SR) stores with caffeine. Treated cells showed a larger Ca2+ transient, ΔF360/380=0.26±0.02, compared to placebo cells, ΔF360/380=0.16±0.01 (p<0.001). In lean CSM, acute exposure to exenatide markedly increased activity of the sarcoplasmic‐endoplasmic reticulum Ca2+ ATPase (SERCA). This activity was confirmed by cyclopizaonic acid block. The increased SERCA activity may explain increased SR Ca2+ store in chronic MetS CSM. Acute exposure of placebo MetS CSM to exenatide has shown no effect on SERCA activity (n=43). Evidence for myocardial resistance to GLP‐1 in MetS is consistent with the lack of acute response. Our interpretation is that chronic exposure attenuates the decline in CSM Ca2+ handling associated with more severe CAD and dedifferentiation of CSM.

(Support: NIH HL062552, TL1 TR000162, Amylin Pharmaceuticals Inc.)
Anticontractile effects of perivascular adipose tissue are increased in obese hypertensive rats
Authors: Szasz Theodora , Nunes Kenia P , Webb R Clinton
Published: June 2021

Perivascular adipose tissue (PVAT) reduces vascular contractile responses in normal conditions. Both hypertension and obesity decrease PVAT anticontractile effects despite having opposite effects on PVAT mass. We hypothesized that PVAT anticontractile effects would be reduced in obese hypertensive rats. Contractile responses in the presence and absence of PVAT were measured in aorta and resistance mesenteric arteries (MA) from control and AngHFHS obese hypertensive rats. Blood pressure and visceral adiposity were significantly increased in AngHFHS compared to control rats. In the absence of PVAT, contraction to phenylephrine (PE) and serotonin (5‐HT) was increased in both aorta and MA of AngHFHS rats. PVAT reduced contractile responses to PE, 5‐HT and ET‐1 in both aorta and MA, however this anticontractile effect was augmented in vessels from AngHFHS rats (anticontractile effect as % reduction in max contraction, con: PE=8.35, 5‐HT=9.53, ET‐1=14.43 vs AngHFHS: PE=36.06, 5‐HT=18.20, ET‐1=39.77). Incubation with DL‐PPG, an inhibitor of cystathionine gamma lyase, partially reverted maximal PE‐induced contraction in PVAT‐intact aorta from AngHFHS, but not control rats. Contrary to our hypothesis, these data suggest that anticontractile function of PVAT is increased in obese hypertensive rats and this may be mediated by an upregulation in the H2S‐producing activity of CSE in the PVAT of these rats.
Angiotensin‐II induced cardiac hypertrophic responses are mediated via PKC and NFAT signaling is attenuated by caveolin‐3 in ventricular myocytes
Authors: Phelan Laura , Reynolds Courtney , Markandeya Yogananda , Roth David M , Patel Hemal H , Balijepalli Ravi C
Published: June 2021

Chronic angiotensin II (AngII) activation leads to cardiac hypertrophy via altered Ca2+ and NFAT signaling. In cardiomyocytes, caveolae containing caveolin 3 (Cav3) localize many signaling proteins to regulate signaling pathways. However, a role of Cav3 in pathological cardiac hypertrophy is unclear. To investigate the role of Cav3 we used in vitro and in vivo models of AngII induced cardiac hypertrophy. Four weeks of AngII infusion in WT mice resulted in cardiac hypertrophy demonstrated by a significant reduction in fractional shortening, ejection fraction and a reduced Cav3 expression but increased PKCα expression in cardiomyocytes. Patch clamp electrophysiology showed reexpression of T‐type Ca2+ current (ICa,T) in myocytes at 4 weeks of AngII infusion (1.6 ± 0.2 pA/pF). In contrast, Cav3 OE (cardiac specific overexpression) and sham mice had normal cardiac function and did not show reexpression of ICa,T. AngII treatment of neonatal myocytes caused significant increases in ICa,T (180%), cell size, and NFAT translocation into nucleus. Knockdown of Cav3 by siRNA further enhanced AngII induced PKCα mediated stimulation of ICa,T (460%). In contrast Cav3 overexpression prevented AngII induced PKCα mediated increase in ICa,T and NFAT signaling. We conclude that Cav3 mediates protective signaling in ventricular myocytes in the setting of pathological cardiac hypertrophy. Research support NHLBI:R01HL105713 & AHA:11GRNT7610094 to RCB.
Thyroid hormone influences calgranulin A and B expression in heart and cardiac myocytes cells
Authors: Takano Ana Paula Cremasco , Moriscot Anselmo Sigari , Barreto‐Chaves Maria Luiza Morais
Published: June 2021

Previous findings of our group showed a global set of responsive genes to triiodotyronine (T3) in the heart including proinflammatory genes. In this context, calgranulin A and B (S100A8 and S100A9 respectively) are proteins associated with decreased contractility and considered important molecules that are able to bind to TLR4 and consequently initiate signaling pathways with fundamental role during inflammatory process. mRNA expression of calgranulin A and B in the heart of rats treated with T3 (7 μg/100g of body weight/day) for 24 h, 7 and 14 days and also in rats neonatal cardiomyocytes stimulated with T3 (10 nM) for 24 h was analyzed by Real Time PCR. TLR4 protein expression was also evaluated by western blot. Data were presented as mean±SD and t test or one‐way analysis of variance was used. P<0.05 values were considered statistically significant. T3 stimulation induced a significant up‐regulation of calgranulin A and B in hearts (2 fold) starting at 24h up to 7 and 14 days and also in isolated cardiomyocytes cells. The TLR4 protein expression was not altered after T3 treatment. The increased calgranulins mRNA levels point to a possible role of proinflammatory genes on cardiac or cardiomyocytic hypertrophy process induced by T3 and additional experiments are being conducted to better answer this question.
Rapid plasma volume restoration increased skin sympathetic nerve activity component synchronized with cardiac cycle and cutaneous vasodilation in hypovolemic and passively warmed men
Authors: Kamijo Yoshi‐ichiro , Okazaki Kazunobu , Ikegawa Shigeki , Okada Yoshiyuki , Nose Hiroshi
Published: June 2021

We have suggested in passively warmed men that skin sympathetic nerve activity (SSNA) involved a component synchronized with cardiac cycle, the component increased as esophageal temperature (Tes) increased, but the increase was suppressed by hypovolemia with reduced cutaneous vasodilation. However, it remained unknown if rapid plasma volume (PV) restoration increased/recovered the component and cutaneous vasodilation. Fourteen young men with ~13% hypovolemia with a diuretic, were divided into 2 groups; time control (n=7, TC) and rapid infusion (n=7, RI). Subjects were warmed for 80min by infusing 47‐°C water into a perfused suit, while Tes, SSNA (microneurography; the peroneal nerve), skin blood flow (SkBF; laser‐Doppler flowmetry; the dorsal foot), and mean arterial pressure (MAP) were measured. After 50‐min warming, the component and cutaneous vascular conductance (CVC=SkBF/MAP) increased (all P<0.0001) as Tes rose by ~0.5°C. Then, when 37‐°C saline was infused at 0.7ml/min/kg for 30min in RI so that PV was restored to the baseline, the component and CVC rose by 17% and 10%, respectively, compared with before infusion in RI (all P<0.03) and the increases were higher than those in TC where saline was infused at 0.1ml/min/kg (all P<0.01). Thus, rapid PV restoration in hypovolemic hyperthermia recovered the component and cutaneous vasodilation.
The effect of progressive heat acclimation on change in body heat content in young males
Authors: Poirier Martin , Friesen Brian J , Hardcastle Stephen G , Kenny Glen P
Published: June 2021

Heat acclimation improves the physiological capacity to dissipate heat. As previous studies have only relied upon core temperature and local heat loss measurements, it remains unclear the extent to which whole‐body heat loss, and therefore body heat storage is altered during heat acclimation. Using direct calorimetry, we examined whole‐body heat exchange during progressive increases in the requirement for heat loss during and following a 14‐day heat acclimation protocol. Six young males (Mean±SD, age: 23±3yrs) performed intermittent exercise (3×30‐min bouts of cycling at 300, 350, and 400 W·m−2separated by 10 min rest period) in dry heat (35°C, 20% relative humidity [RH]) prior to (day 0), during (day 7), and at the end (day 14) of a 14‐day heat acclimation. On days 1–6 and 8–13, subjects cycled for 90 min (~50% VO2max) in the heat (40°C, 20% RH). Despite a similar requirement between test days, significantly lower increases in evaporative heat loss were observed for the final exercise bout in days 0 (P=0.01) and 7 (P=0.02) relative to day 14. After 7 days of acclimation, the ΔHb following the exercise did not significantly decrease from day 0 (673±165 vs. 449±109 kJ, p=0.112). However, on day 14 the ΔHb was significantly reduced compared to day 0 (363±64 vs. 673±165 kJ, p=0.04). These data suggest that 14 days is necessary to achieve sufficient heat acclimation to significantly reduce heat storage during exercise in the heat. Support: Deep Mining Research Consortium (Dr. Glen P. Kenny)
A computer‐controlled system for simulating heat stroke in vitro
Authors: Clarke David C , Zhou Dennis , Inman Walker , Barker Caroline J , Leon Lisa R , Lauffenburger Douglas A
Published: June 2021

Heat stroke (HS) is an important civilian and military medical problem. Characterizing the cellular responses to HS is critical for improved diagnosis and treatment of HS. Commonly used in vitro heat “shock” models inadequately represent the physiological stressors experienced by cells during HS in vivo. The objective of this study was to create a high‐precision in vitro system to dynamically expose cultured cells to core‐temperature (Tc; radiotelemetry) profiles exhibited by mice during HS and recovery. We assembled a system consisting of a Peltier plate, feedback controller, thermistor probe and custom software to expose cultured cells to mouse Tc profiles. HepG2 cells and primary mouse and rat hepatocytes were maintained on the Peltier plate in a CO2 incubator with a thermistor probe immersed in a single well for feedback control. Our system replicated mouse Tc profiles with an average error of ~0.3°C. All cell types tolerated heat stress to 42.7°C, with no differences in cell viability or morphology either immediately or 24 hr after heat exposure compared to untreated cells. Our system will support future studies examining cell responses to the temperature and inflammatory stresses that occur during HS. Supported by the Defense Health Program (DHP) in support of the Department of Army (DOA) Systems Biology Enterprise (SBE). Author views not official US Army or DOD policy.
Investigation of Bisphenol A administration on skeletal muscle force generation in mice
Authors: Benson Marisa C , Liang Chen , Receno Candace N , DeRuisseau Keith C
Published: June 2021

Bisphenol A (BPA) is a chemical used in the manufacturing of numerous products including plastics and food‐contact materials and is classified as an endocrine disruptor because it can mimic actions of estrogen in the body. The purpose of this study was to examine BPA effects on muscle force generation since estrogen may influence muscle contractile properties. Eight‐week old male CD‐1 mice were housed in polypropylene cages and provided a soybean oil‐free diet (AIN‐93G) (control; C) for two weeks. Thereafter, animals were randomly assigned to C (n=5), C+BPA (BPA; 50 mg BPA/kg diet; n=4), or C+ethinyl estradiol (EE; 0.1 ppb; n=5) diets for one month. Soleus muscles were harvested for measurement of twitch and tetanic force generation (N/cm2) in vitro. Peak twitch tension of EE (3.5±0.1) was greater (p<0.05) than BPA (2.6±0.1) and C (2.8±0.2). Peak tetanic tension of EE (24.8±1.2) was greater (p<0.05) than BPA (19.2±0.7) but was similar (p>;0.05) to C (22.31±0.3). Soleus force generation between BPA and C was similar (p>;0.05). Post‐experiment animal body mass and soleus muscle mass did not differ between groups (p>;0.05). Preliminary findings revealed augmented force generation of the soleus following administration of EE, but not BPA. Therefore, BPA administration does not appear to influence twitch or maximal force generation of mouse soleus muscle.

Supported by the Hill Collaboration on Environmental Medicine (KCD)
Heme Oxygenase‐1 Inhibition Does Not Prevent MnTBAP's Ability to Reduce Adiposity and Increase Insulin Action
Authors: Brodsky Timothy W , Sosinsky Alexandra Z , Donohue Jacob , Schwarz Daniel , Sheppard Aaron , Reynolds Thomas H.
Published: June 2021

Metalloporphryins have been shown to cause weight loss by a heme oxygenase‐1 (HO‐1) dependent mechanism. The purpose of this study was to determine if inhibiting HO‐1 with tin mesoporphyrin (SnMP) prevents the reduction in adiposity and the improvement in insulin sensitivity due to manganese tetrakis benzoic acid porphyrin (MnTBAP) treatment. Mice were fed a low fat diet (LFD) or a high fat (HFD) for four months. During the last 30 days of the dietary intervention, mice were given intraperitoneal injections of MnTBAP (10 mg/kg/day), MnTBAP+SnMP (20 mg/kg/day), or vehicle. SnMP treatment did not prevent the ability of MnTBAP to significantly decrease body weight (Vehicle: 42.5±1.8 vs. MnTBAP: 36.7±1.4 vs. MnTBAP+SnMP: 35.8±1.0) or epididymal white adipose tissue (EWAT) weight (Vehicle: 2.52±0.10 vs. MnTBAP: 1.88±0.14 vs. MnTBAP+SnMP: 1.66±0.11). Insulin sensitivity was significantly higher in HFD mice treated with MnTBAP or MnTBAP+SnMP when compared to vehicle treated HFD mice. Since carbon monoxide (CO) is a product of the HO‐1 reaction, it may mediate the anti‐obesity effects of metalloporphyrins. However, treating HFD mice with CO (250 ppm, 1 hr/day, 4 weeks) did not result in a reduction in body weight or EWAT weight, and did not improve insulin sensitivity. These results indicate that the ability of MnTBAP to promote weight loss and improve insulin sensitivity is independent of HO‐1 activity.
Metabolic Syndrome alters the balance of prostaglandins in hypoxia‐mediated cerebral vasodilation
Authors: Harrell John W , Yanke Peter A , Schrage William G
Published: June 2021

Cerebral vasodilation to hypoxia is achieved, in part, through vasodilatory prostaglandin production. Hypoxia‐mediated cerebral vasodilation is decreased in metabolic syndrome (MetSyn), and animal data suggests it is due to decreased prostaglandin formation. We hypothesized MetSyn adults will exhibit decreased contribution of prostaglandins to hypoxia‐mediated cerebral vasodilation. We measured middle cerebral artery velocity (MCAv) with transcranial Doppler ultrasound in younger MetSyn (n=8, 32±3 yr) and healthy adults (n=10, 32±2 yr). Isocapnic hypoxia was induced by titrating inspired oxygen to lower arterial oxygen saturation to 80% for 5 minutes. Hypoxia was conducted on two separate days after ingestion of indomethacin (100mg) or placebo. MCAv was normalized for group differences in blood pressure (cerebrovascular conductance index, CVCi). A change in CVCi (ΔCVCi) was calculated to assess cerebral vasodilation. Hypoxia induced a significant increase in CVCi in both groups (p<0.05). However, indomethacin increased hypoxia‐mediated ΔCVCi by 86% in MetSyn and reduced ΔCVCi in controls by 34% (p<0.05). Our data suggest the contribution of prostaglandins to hypoxia‐induced cerebral vasodilation is altered in MetSyn. Specifically, it appears MetSyn adults have increased production of vasoconstricting prostaglandins in the cerebral vasculature. AHA PRE7390038 & NIH HL105820
The effects of bolus versus pulse feeding strategies on muscle anabolism in older men
Authors: Mitchell William Kyle , Williams John , Rankin Debbie , Lund Jonathan , Phillips Bethan , Smith Kenneth , Atherton Philip J
Published: June 2021

A topical advancement in understanding the control of muscle protein synthesis (MPS) was the discovery of a “Muscle‐Full” phenomenon, whereby feeding stimulates only transient increases in MPS, which return to postabsorptive values despite sustained availability of plasma and muscle essential amino acids (EAA) including leucine. Herein, we have explored this phenomenon in relation to aging by measuring MPS (13C6‐phenylalanine bound muscle) over a 6 h period (2 h fasted ‐4 h fed) using two distinct feeding regimens: 16 older men received either a single 15g mixed EAA feed (N=8, 70±2 y; ‘BOLUS’) or the same dose in 4 × 3.75g fractions at 45 min intervals (N=8, 70±3 y; ‘PULSE’). While MPS was unchanged in either group 0–90 min after EAA ingestion, it was elevated 91–180 min, irrespective of feeding strategy (BOLUS: 0.049 to 0.082 vs. PULSE: 0.046 to 0.071%.h−1, P<0.05 2‐way RM ANOVA). In contrast, while MPS returned to baseline rates in BOLUS between 181–240 min (to 0.052%.h−1) this was not the case in PULSE (0.070%.h−1, P<0.05). Despite these temporal differences equal total MPS responses to feeding regimens were revealed by area under the curve analysis (0.27% vs. 0.24% in 4 h, P>;0.05). While equal total MPS between regimens suggests a dose, not time‐dependent mechanism regulates the muscle‐full state in older men, greater sustainment of the anabolic response over longer durations with PULSE feeding regimens may transpire.
Role of secondary structure in protein‐lipid interactions: decreases in the helical content of apolipoprotein C‐I lower its affinity for triolein/water and phospholipid/triolein/water interfaces
Authors: Meyers Nathan , Wang Libo , Gursky Olga , Small Donald
Published: June 2021

Binding of exchangeable apolipoproteins to lipoprotein surfaces is mediated by amphipathic α‐helices. To probe the role of α‐helical structure in protein‐lipid interactions, we used oil‐drop tensiometry to characterize the interfacial behavior of apolipoproteinC‐I (apoC‐I) and its mutants at TO/W and palmitoyloleoylphosphatidylcholine/triolein/water (POPC/TO/W) interfaces. ApoC‐I, the smallest apolipoprotein (57 amino acids), has two amphipathic α‐helices from residues 7–29 and 34–47. Mutants contained single Pro or Ala substitutions, such that they differed in helical content in solution (0–48%) and on lipid (40–75%). Tensiometry results showed that apoC‐I binding to and modification of TO/W and POPC/TO/W interfaces correlated strongly with aqueous helical content. On binding both types of interfaces, peptides with higher aqueous helical content increased surface pressure (Π) to a greater extent. The Π at which peptides were excluded from POPC/TO/W interfaces increased with greater aqueous helical content. ApoC‐I retention on TO/W and POPC/TO/W interfaces correlated strongly with lipid‐bound helical content. Peptides with higher lipid‐bound helical content were ejected from compressed interfaces at higher Π. These results support a model in which α‐helix affinity for lipoproteins increases with greater aqueous and lipid‐bound helical content. This model explains the higher lipid affinity of apoC‐I than apoC‐II, whose two lipid binding α‐helices differ from those of apoC‐I primarily in helical content.
Extraocular muscles produce more non‐mitochondrial reactive oxygen species
Authors: Sims Lorrie , Garcia‐Cazarin Mary , Andrade Francisco
Published: June 2021

Extraocular muscles (EOM) are constantly active, and have a high mitochondrial content. We previously showed that EOM mitochondria are different (Invest Ophthalmol Vis Sci 50:180–6, 2009). Here, we investigated this hypothesis: EOM mitochondria produce more reactive oxygen species (ROS) than mitochondria from other muscles. First, we measured ROS production in diaphragm muscle bundles and intact EOM, excised from adult male Sprague Dawley rats, and loaded with 2’,7’‐dichlorofluorescein‐diacetate (DCFH‐DA). Next, ROS generation was measured for 60 min with Amplex Red in respiring mitochondria from rat diaphragm, gastrocnemius, and EOM. Intact EOM oxidized more DCFH: 1532 ± 407 vs. 517 ± 77 arbitrary units (AU, mean ± SD), EOM and diaphragm, respectively, n=5 muscles, p=0.04. Amplex Red oxidation was not different in mitochondria from the 3 muscles during state 3 respiration (driven by glutamate/malate), inhibition of complex I with rotenone, or succinate‐driven respiration. EOM mitochondria oxidized less Amplex Red during succinate‐driven respiration combined with complex III inhibition using antimycin: 15570±2135, 13305±1020, 9502±1024 AU, diaphragm, gastrocnemius, and EOM respectively; p=0.0009, n=4 rats). These results show that intact EOM generated ROS faster than diaphragm bundles. However, EOM mitochondria did not produce more ROS than mitochondria from other muscles. Therefore, we reject our initial hypothesis, and propose that the higher rate of ROS production in EOM originates from non‐mitochondrial sources.

*Research supported by APS Undergraduate Research Fellowship 2012
Post‐translationally modified cardiac mitochondrial VDAC1 gating kinetics analyzed using continuous‐time MCMC model
Authors: Tewari Shivendra , Zhou Yifan , Camara Amadou KS , Dash Ranjan K , Kwok Wai‐Meng
Published: June 2021

Mitochondrial homeostasis, maintained via the outer mitochondrial membrane (OMM), is critical for maintaining mitochondrial function. The voltage‐dependent anion channel (VDAC1 isoform) is the most abundant protein on the OMM, and it regulates the exchange of ions and molecules across the membrane. VDAC1 possesses a remarkable ability to conduct metabolites and anions in its high conductance state and cations in its low conductance state. Despite its significance, no integrated mitochondrial bioenergetics model incorporates for VDAC1. Our electrophysiological recordings of VDAC1 incorporated into lipid bilayers revealed that post‐translational modification by phosphorylation and nitration significantly impacted VDAC1 gating kinetics. Consequently, a thorough statistical treatment was applied by modeling VDAC1 activity using a generalized continuous‐time Markov chain Monte Carlo (MCMC) method. The MCMC method returns probability distribution of identified model parameters from which important model information such as appropriateness and parameterization can be easily obtained. Our analyses suggest that phosphorylation and nitration of VDAC1 facilitate multiple conductance states wherein a simple kinetic model incorporating three open states (O1 ↔ O2 ↔ O3) fit the experimental data. The long‐term goal is to link the changes in VDAC1 gating kinetics to mitochondrial function.
Heat Shock Protein 27 (hsp27) Translocation to the Mitochondria is Associated with Protection Against Diabetic Cardiomyopathy.
Authors: Lee Shepherd Danielle , Croston Tara L. , Lewis Sara E. , Nichols Cody E. , Thapa Dharendra , Jagannathan Rajaganapathi , Hollander John M.
Published: June 2021

Cardiac complications are the leading cause of mortality among diabetic patients, with the mitochondrion being implicated in the etiology. Heat shock protein 27 (hsp27), is a cardioprotective cytosolic protein. We hypothesized that hsp27 overexpression would attenuate cardiac contractile dysfunction associated with diabetes mellitus through a direct mitochondrial effect. Type 1 diabetes mellitus was induced using multiple low dose streptozotocin injections. Echocardiographic data indicated preserved cardiac contractile function with hsp27 overexpression (%EF and %FS). Analysis of mitochondrial subfractions revealed the presence of hsp27 in the mitochondrion, primarily in the inner membrane space. Hsp27 immunogold stained electron micrographs and flow cytometry showed enhanced translocation of the protein in the transgenic diabetic animals, as compared to littermate and diabetic controls. Mitochondrial membrane potential and state 3 respiration were decreased in diabetic IFM compared to littermate IFM, and restored in hsp27 transgenic animals (P < 0.05). Together these results indicate that overexpression of hsp27 elicits cardioprotection during type 1 diabetic insult through the preservation of mitochondrial and contractile function which is associated with increased presence of hsp27 in the mitochondrion. (Support: NIH‐DP2DK083095, 5T32HL090610, S10 RR‐026378, DGE‐1144676).
Leptin but not its long form receptor regulates intestinal membrane expression of sodium/glucose transporter‐1 and intestinal hyperplasia
Authors: Rieg Jessica A Dominguez , Gerasimova Maria , Koepsell Hermann , Rieg Timo
Published: June 2021

Small intestinal hyperplasia occurs in type 2 diabetic conditions and is associated with alterations in intestinal Na+/glucose transporter 1 (SGLT1) abundance. To study the role of leptin and its receptor in intestinal hyperplasia and expression of SGLT1, we utilized leptin‐receptor (LEP‐R) deficient mice with compensatory increased leptin levels (db/db; n=6), leptin‐deficient mice (ob/ob; n=5), and their controls (db/con and ob/con, n=10 and 6, respectively). Db/db and ob/ob were obese (46±1 vs 27±2 g and 46±1 vs 25±1 g, respectively; P<0.01) and hyperglycemic (532±24 vs 120±4 mg/dl and 315±34 vs 168±9 mg/dl, respectively; P<0.01) vs con. Both db/db and ob/ob had longer small intestines vs controls (37±2 vs 30±1 cm and 37±1 vs 32±1 cm, respectively; P<0.01). Db/db had longer villi (673±14 vs 483±20 μm; P<0.01) and deeper crypts (112±2 vs 98±3 μm; P<0.01) vs db/con. In contrast, ob/ob and ob/con had comparable villi lengths (416±15 vs 397±6 μm; P=NS) and crypt depths (63±3 vs 70±2 μm; P=NS). In db/db, immunofluorescence revealed SGLT1 apical membrane abundance was nearly absent and SGLT1 protein expression was decreased vs db/con (44%±10 vs 100%±8; P<0.01). In contrast, apical membrane abundance in ob/ob vs ob/con was not different. Increased leptin levels in type 2 diabetes may regulate intestinal glucose transporter abundance independent of the long form of the LEP‐R and may contribute to intestinal hyperplasia.
Generalized Epithelial Transport Modeling: Computational Physiology
Authors: Nickerson David Phillip , Lee Hamilton Kirk , Terkildsen Jonna , Hunter Peter John
Published: June 2021

We present an epithelial modeling tool facilitating the development and validation of models of individual transport processes and whole cell transport. Making use of established standards in computational physiology, our tool enables the user to assemble epithelial cell models from a library of reusable transport process descriptions, starting from either a blank canvas or pre‐existing templates and models from the library. We are developing a library of reusable renal epithelial transport models, ranging from models of individual transporters to whole cell models. Our tool makes use of biological information associated with these models, such as location within a cell membrane or identification of the ions being transported, to guide the user in the assembly of new models. This, combined with other associated information in our library, enables the user to determine a suitable starting point for their work. Such as adding a novel model of the SGLT2 to an existing proximal tubule cell model; or a generic epithelial cell ready for specific transporter models. We additionally associate experimental protocols with the mathematical models, which allow the user to compare their work against existing data. Users are able to contribute new models, protocols, and data to the library for easy dissemination to, and reuse by, the community. Supported by the Virtual Physiological Rat Project, NIH grant [P50‐GM094503].
Energy restriction blocks bone marrow dendritic cell development
Authors: Duriancik David M. , Clinthorne Jonathan F , Gardner Elizabeth M
Published: June 2021

Dendritic cells (DC) are antigen presenting cells and sensitive to nutritional modulation. Energy restriction (ER) is a nutritional intervention shown to extend lifespan in many experimental organisms, but recent data in non‐human primates is contradictory. Immunological outcomes of ER are mixed with several reports demonstrating ER amelioration of autoimmune disease, but ER mice are also more susceptible to some primary infections such as influenza. Due to glucocorticoid‐associated increased myelopoiesis, we hypothesized bone marrow DC development would be increased. The objective of this study was to determine the effects of ER on bone marrow DC progenitor numbers. Multicolor flow cytometry was used to characterize bone marrow DC progenitors. We observed increased myeloid progenitors and monocytes, while common DC progenitors and precursor DC were decreased in bone marrow of ER mice. Altered progenitor populations had no effect on in vitro DC development. Therefore we conclude ER bone marrow microenvironment is altered favoring myelopoiesis over lymphopoiesis, but myelopoiesis is also altered. The altered developmental pathway of DC subsets may be responsible for contradictory immunological outcomes of ER populations and provide potential targets for improving vaccination, autoimmune conditions, and infectious disease.

Grant Funding Source: NIA R01AG034949 to EMG
Integrative experimental approaches to adaptive interpretations of the fossil record
Authors: Ravosa Matthew J
Published: June 2021

In vivo analyses facilitate a direct knowledge of how a feature or anatomical complex is used during an organism's lifetime, information critically important for increasing the efficacy of comparative studies of living and fossil taxa. In the mammalian skull, dietary properties have a pronounced influence on the ontogeny of the masticatory apparatus. Diet‐related variation in loading levels induces a cascade of changes at the gross, tissue, cellular, protein and genetic levels, with such tissue modeling and remodeling maintaining the integrity of oral structures. Ongoing integrative research using a rabbit model of long‐term dietary plasticity in jaw joints offers unique insight into the caveats or limits on morphological inference that apply to functional interpretations of fossil remains. First, as the fossil record consists primarily of bony elements, analyses that fail to account for the disparity in the hierarchical network of responses of hard vs. soft tissues may considerably overestimate the adaptive signal based on phenotypic differences between morphs. Second, the developmental onset and duration of a loading stimulus associated with a given feeding behavior can impart a considerable effect on patterns of intraspecific variation that can mirror differences observed between taxa. Marked variation in joint form, and even joint function, can also characterize adult conspecifics that differ in age.
Regulation of Alternative Splicing
Authors: Hertel Klemens , Mueller William , Busch Anke , Erkelenz Steffen , Schaal Heiner
Published: June 2021

The recognition splice sites is aided by cis‐acting splicing regulatory elements that either activate or repress splice site selection. Over the past years it has been established that members of the SR splicing factors activate splicing and that members of the hnRNP family repress exon recognition, leading to the commonly accepted designation of SR proteins splicing enhancers and hnRNP proteins splicing repressors. However, recent genome‐wide analyses called this strict designation into question We set out to determine whether dual and antagonistic functionality is a common feature of SR and hnRNP splicing regulators. Our results prove that indeed this is the case, but only in a strict position‐dependent manner. SR proteins activate splicing only from within exons, but repress exon recognition from intronic positions. For hnRNP splicing factors we show analogous opposing activities, but in a reversed position dependence. Both types of splicing regulatory proteins display highly position‐dependent activities that negatively or positively influence splice site choice. These results challenge current computational approaches to define the splicing code.
Longitudinal changes in bone turnover markers following Roux‐en‐Y gastric bypass surgery
Authors: Rogers Tara Sheree , Havel P J , Wolfe B M , Blankenship J , Stanhope K L , Van Loan M D , Swarbrick M M
Published: June 2021

Bariatric surgery is associated with changes in bone metabolism; the mechanism is unclear. We examined changes in bone turnover for 1 yr following Roux‐en‐Y gastric bypass surgery (RYGBP). Obese adults (n=20; BMI 45.6 ±1.6 kg/m2) were studied pre and 1, 3, 6, and 12 months post‐RYGBP. Bone specific alkaline phosphatase (BAP) and N‐telopeptide of type I collagen (NTx) were measured by ELISA. ANOVA was used to evaluate differences over time. We modeled the contributions of body weight, energy related hormones and inflammatory markers to BAP and NTx. The BAP/NTX ratio declined significantly (p<0.0001) within 1 month of surgery and remained low for 12 mo. post RYGB. Before surgery, glucose and free fatty acids (FFA) explained 35.3% of the variance in BAP/NTX; post RYGBP, 48% of variance in BAP/NTx was explained by glucose, insulin and c‐reactive protein (CRP). Neither weight nor composition contributed to the BAP/NTX ratio. BAP and NTx may be influenced by energy related hormones and inflammatory markers; more research is needed to elucidate relationships among these variables and bone metabolism.

Pre
Partial R2
12‐Mo Post
Partial R2

Intercept
−0.32656

4.07734

Glucose
0.01826
0.2334
−0.040
0.216

FFA
1.96974
0.1198

Insulin

0.00848
0.169

CRP

−0.05015
0.101

Model R2

0.353

0.481

Funding: UC Davis Health Care Systems grant; UC Davis CTSC (UL1 RR024146); National Center for Research Resources; USDA/ARS/WHNRC.
Calcium and vitamin D supplements do not prevent loss of bone mineral density in women undergoing therapy for breast cancer
Authors: Datta Mridul , Schwartz Gary G
Published: June 2021

Women with breast cancer (BC) are at an increased risk of osteoporosis due to accelerated bone loss caused by BC therapies. Since calcium &/or vitamin D (Ca±D) are frequently recommended for osteoporosis prevention & management to women undergoing BC therapy, we examined the effects of Ca±D supplements in preventing bone loss in these women. We reviewed guidelines for Ca±D supplementation in women with BC & conducted a systematic review of Ca±D supplementation trials in maintaining skeletal health in women with BC. We used the “before‐after” data from the comparison groups of trials that evaluated the effect of drugs such as bisphosphonates on bone mineral density (BMD) in which Ca±D were used as the comparison group. The effect of Ca±D supplements on BMD in women with BC undergoing BC therapy has not been tested against an unsupplemented control group. However, results from 15 trials of “before‐after” comparison indicate that supplements of 500 – 1500 mg calcium & 200 – 1000 IU vitamin D were inadequate to prevent loss of BMD in women with BC. Mean loss of BMD at the lumbar spine in pre‐ & postmenopausal women was −5.6% & −2.3%. Additionally, other evidence indicates that both BC therapies & calcium supplements may increase the risk of cardiovascular disease. Because cardiovascular disease is the main cause of mortality in women with BC, future trials should evaluate the safety & efficacy of Ca±D supplementation in these women.

Grant Funding Source: Dr. Datta is supported by the Comprehensive Cancer Center of Wake Forest University Cancer Control Traineeship – NCI/NIH Grant# #R25CA122061
Obesity acclerates pancreatic tumor growth and increases the accummulation of myeloid derived suppressor cells
Authors: Collins Shawntawnee , Turbitt William J. , Rogers Connie J.
Published: June 2021

Obesity increases the risk of several solid tumors, including pancreatic cancer. One mechanism underlying the obesity‐induced increase in tumor incidence may be an obesity‐induced increase in tumor‐derived immunosuppressive factors. Thus, the goal of the current study was to evaluate the effect of diet‐induced obesity on pancreatic tumor growth, survival and the emergence of myeloid derived suppressor cells (MDSC). MDSC inhibit anti‐tumor immunity, and expand significantly as a result of numerous tumor‐derived inflammatory signals commonly elevated in obesity. C57BL/6 mice (n=8/gr) were fed either a 30% calorie restricted diet; a 10% kcal from fat diet fed ad libitum; or a 60% kcal from fat diet fed ad libitum to generate lean, control and obese mice, respectively. Mice were injected with 1 ×106 Panc02 pancreatic tumor cells after 8 weeks on each diet. Obese mice had significantly greater tumor volumes beginning at day 25 post‐tumor implantation (P<0.05), and reduced median survival as compared to lean animals (77.5 vs. 61.5 days; P<0.05). Obese mice also accumulated significantly greater number of MDSC in the spleen as compared to lean animals (87.7± 50.5 ×106 vs. 25±3.5 ×106;P<0.05). These results demonstrate that obesity accelerates pancreatic tumor growth concurrently with an increase in immunosuppressive MDSCs. Future studies will explore possible mediators of obesity‐induced MDSC accumulation.

Grant Funding Source: Pennsylvania State University Internal Funding
Predicting lower extremity pain based on foot morphology and computerized gait analysis in obese children
Authors: Wong William W , Ross Jeffrey A , Abrams Stephanie H , Barlow Sarah E , Klish William J
Published: June 2021

Promoting physical activity is a key component of all childhood obesity intervention programs. Unfortunately, physical activity puts greater strain on the musculoskeletal system. Obese children may have altered foot morphology and gait instability, which may interfere with physical activities. We assessed the foot morphology and gait among 40 obese children (11.4±1.4 y; 75% female; 17 white, 5 black, 18 Hispanic) who enrolled in a summer camp program. The assessment was done visually and using a pressure mapping MatScan System. Each child was rated for risk of lower‐extremity pain on the first 2 days of camp.

Results

Pronation was diagnosed in 93% of the children. Adducted gait, pes planus and genu vaglum were each present in half of the children. Approximately 65% of children reported lower extremity pain at camp. The prediction of risk showed significant agreement (Kappa = 0.624, p<0.01) with pain. BMI z‐scores decreased less at the end of the 2‐week camp among children who reported lower‐body musculoskeletal pain (−0.101±0.352) than children who reported no pain (−0.118±0.352, p=0.12).

Conclusion

We hypothesize that treating altered foot morphology and gait instability with supportive shoes, accommodative insoles, and/or prescription insoles might present an effective approach to prevent pain and overuse injuries and thereby encourage physical activity among obese children. USDA/ARS 6250–51000‐053.
Behavior change counseling (BCC) by frontline health workers (FHW) and a mass media campaign improved complementary feeding (CF) practices more than mass media alone in rural Bangladesh
Authors: Saha Kuntal Kumar , Rawat Rahul , Khaled Adiba , Sanghvi Tina , Afsana Kaosar , Haque Raisul , Siraj Saiqa , Ruel Marie T , Menon Purnima
Published: June 2021

We assessed the effects of combining a mass media campaign with BCC by FHW on CF practices in Bangladesh. Survey data were collected from randomly sampled households with children 6–23 mo in 2010 (baseline; N=250 per group) and 2012 (mid‐point; N=230 per group) from 10 sub‐districts cluster‐randomized to either an intensive (FHW + mass media) or a non‐intensive (mass media only) intervention. Exposure to FHW and television spots (TVS) on 6 child feeding themes was measured using aided recall methods. CF practices were measured using WHO‐recommended indicators. In 2010, home visits by FHW and prevalence of optimal CF practices were very low with no significant differences between study areas. In 2012, home visits by FHW were significantly higher in intensive (60%) than in non‐intensive (17%) areas. Percentage of mothers who received advice from FHW on IYCF was 2.5 times higher in intensive areas. In both areas, 20–50% of mothers saw the TVS on 6 themes. Significantly higher proportions of children in intensive areas achieved minimum diet diversity (p<0.01) and minimum acceptable diet (p<0.05), and consumed iron rich foods (p<0.001) than in non‐intensive areas. At this 2‐y time point in the study, mothers who received both FHW counseling and mass media had significantly better CF practices than those who were exposed to mass media only. Funded by Bill & Melinda Gates Foundation, through Alive & Thrive, managed by FHI360.