bluuebunny/crossref_metadata_2025 huggingface dataset:
Low‐dose intra‐nasal cocaine causes subclinical microvascular coronary ischemia in humans
Authors: Nelson Michael , Gurudevan Swaminatha V. , Tang Xiu , Lewis Joshua , Johannes Jimmy , Belcik Todd , Lindner Jonathan R. , Victor Ronald G.
Published: June 2021

We used myocardial contrast echocardiography (MCE) to test the hypothesis that cocaine, an indirect sympathomimetic, causes microvascular ischemia in the human heart. Measurements were performed at baseline and after low‐dose, non‐intoxicating, intranasal cocaine (2 mg/kg) in 10 healthy cocaine‐naïve men (median age 32 yrs). Destruction‐refill data on MCE were fit to the equation: y = A(1‐e− βt) to quantify functional capillary blood volume (A), flux rate (β) and myocardial blood flow (MBF) (Product of A and β). Heart rate (HR), mean arterial pressure (MAP), and left ventricular (LV) work (end‐systolic elastance × HR) were measured. Validation experiments included with‐in day reproducibility, control experiments using low‐dose dobutamine, and cross‐modality experiments comparing MCE with first‐pass magnetic resonance perfusion imaging. Cocaine caused a rise (p<.05) in MAP (+14±2 mmHg), HR (+8±3 bpm), and LV work (+50±18%). Despite this significant rise in oxygen demand, MBF declined significantly (103.7±9.8 to 75.9±10.8 a.u.) due mainly to reductions in capillary blood volume (133.9±5.1 to 111.7±7.7 a.u., p<.05) with no change in feed artery flow velocity (0.8±0.1 to 0.7±0.1 a.u.). We conclude that cocaine‐induced sympathoexcitation acts at the level of the coronary microvessels, to cause a mismatch between myocardial oxygen demand and MBF.
Exercise training in childhood cancer survivors with subclinical cardiomyopathy
Authors: Smith Webb A , Ness Kirsten K , Joshi Vijay M , Hudson Melissa M , Robison Leslie L , Green Daniel M
Published: June 2021

Childhood cancer survivors (CCS) treated with anthracyclines are at risk for cardiomyopathy. This study evaluated the feasibility and effects of aerobic and strength training among anthracycline exposed CCS with subclinical cardiomyopathy. Body composition, strength and cardiopulmonary fitness were evaluated before and after the 12‐week intervention. All equipment and materials were provided for an American College of Sports Medicine guideline based home exercise program to five 10+ year survivors of bone tumors (3 males, mean age 38.0±3.3 years). All 5 completed the study with no adverse events. Compliance with prescribed exercise was 86%. These results suggest that exercise training among survivors with subclinical cardiomyopathy is safe and may improve exercise capacity. Funding provided by a Cancer Center Support (CORE) grant CA 21765 and ALSAC.
Heat production per unit mass determines the core temperature response to exercise in compensable conditions
Authors: Cramer Matthew N. , Jay Ollie
Published: June 2021

We hypothesized that the change in core temperature during exercise in compensable conditions is determined by heat production per unit mass (W/kg), and not absolute heat production (W) or the percentage of peak oxygen uptake (%VO2peak). Nine heat‐acclimated males of high (HI: 89.1±6.3 kg, n=6) or low (LO: 67.2±5.7 kg, n=3) body mass cycled at 500 W, 6.5 W/kg, and 9.0 W/kg in 25°C, as well as 9.0 W/kg in 35°C. Heat production was estimated using indirect calorimetry, and rectal temperature (Tre) was measured throughout. At 500 W (HI: 5.7±0.1 W/kg, LO: 7.3±0.2 W/kg; p<0.001), the change in Tre (ΔTre) was greater in LO (HI: 0.51±0.06°C, LO: 0.96±0.10°C; p=0.007) despite similar %VO2peak (HI: 45±3%, LO: 47±1%; p=0.573). At all W/kg, ΔTre was not different between groups, yet %VO2peak was greater in HI at 6.5 W/kg (HI: 50±3%, LO: 42±1%) and 9.0 W/kg (HI: 67±2%, LO: 57±3%). A similar ΔTre was observed within each group at 9.0 W/kg in 25°C and 35°C (p>;0.05). In summary, our data suggest core temperature responses between participants in compensable conditions should be compared by administering exercise intensity based on heat production per unit mass, not absolute heat production or %VO2peak.

Supported by a NSERC Discovery Grant (O. Jay)
Developmental hyperoxia attenuates hypoxic ventilatory depression in neonatal rats
Authors: Bavis Ryan W , Grandgeorge Samuel H , Hill Corey B
Published: June 2021

Rats reared in hyperoxia exhibit a sustained (vs. biphasic) hypoxic ventilatory response (HVR) at an earlier age than untreated, control rats (Bavis et al., J Appl Physiol 109:796–803, 2010). Since ventilatory decline in the late phase of the biphasic HVR is linked to inhibitory modulation of respiratory neurons in the CNS, we hypothesized that hyperoxia‐treated rats would exhibit less CNS‐mediated hypoxic ventilatory depression. We used the P2X receptor antagonist PPADS (125 mg kg−1, i.p.) to “chemically denervate” the carotid bodies (CB) of 4–5‐day old rats reared in 21% O2 (Control) or 60% O2 (Hyperoxia). PPADS had no effect on the hypercapnic ventilatory response (7% CO2) but abolished the early, carotid body‐mediated phase of the HVR (12% O2) in Control rats. Control rats showed a progressive decline in ventilation during hypoxia (−28±4% by 10 min, n=18), but this effect was absent in Hyperoxia rats (−2±4%, n=18; P<0.001 vs. Control). We conclude that CNS hypoxia depresses ventilation in young, neonatal rats independent of CB activation. Moreover, our data suggest that hyperoxia alters the development of CNS pathways that modulate the hypoxic ventilatory response.
Autonomic Function Assessed with Heart Rate Variability in Everest Climbers
Authors: Marck Jan Willem , Issa Amine , Taylor Brian , Summerfield Doug , Kasak Alex , Johnson Bruce
Published: June 2021

BACKGROUND

Exposure to high altitude (HA) results in sympathetic nervous system (SNS) activation. This might interact with HA related illness. HRV is a technique to quantify SNS and parasympathetic nervous system (PNS) interactions and thus offers a noninvasive index in extreme environments.

OBJECTIVE

To quantify the changes in HRV in elite athletes (AT), acclimatized for 2 mo. at Everest base camp (BC) prior to summiting, relative to a control group (CT) (climbing and acclimatizing to BC in 3 wks).

METHODS

AT (N=4, Age=35±10 y, BMI=22±2, M/F ratio 2/2) and CT (N=8, Age=35±10 y, BMI=26±2, M/F ratio 8/0) performed autonomic tests consisting of quiet breathing, paced breathing prior to, mid‐way at BC and at 2 wks post expedition.

RESULTS

At BC, AT had (compared to CT) higher HR (p=0.07) and reduced HRV (SDNN, p=0.09). For AT and CT combined: measures of HRV were reduced at BC (SDNN, p=0.05, Poincare length, p=0.05) and remained below baseline 2 wks post climb (SDNN, p=0.01; PCL, p=0.01).

CONCULSION

HRV is reduced with HA exposure in both AT and CT and remains reduced 2 wks post exposure, suggesting either SNS activation and/or PNS withdrawal.

FUNDING: Mayo Clinic & The North Face.
Endogenous estrogen enhances brachial blood conductance during dynamic handgrip in young healthy and metabolic syndrome women
Authors: Restaino Robert , Schwermann Trace , Blankenship Aaron , Barlow Matthew A
Published: June 2021

Fadel et al. (2004) reported that in women, estrogen can attenuate sympathetic vasoconstriction as seen in postmenopausal women given estrogen treatment and increased vascular conductance. We hypothesize that women during the low estrogen phase of menses with metabolic syndrome (MetS) have an attenuated brachial conductance compared to normal controls. Participants were tested during the early menses (low estrogen, low progesterone) and the proliferative phase (high estrogen, low progesterone). Participants engaged in dynamic handgrip exercise (30 contactions/min) with a ramped increase in workload (0.5kg resistance/min) until task failure. Vascular velocity and diameter were measured during exercise in the brachial artery by Doppler ultrasound; heart rate and blood pressure were repeatedly recorded. The data demonstrate that MetS (25.3 years +1.58) have an attenuated conductance response (MetS 4.78×10^−3+0.7×10^−3 ml/min/mmHg/L, n=5) vs Control 9.4×10^−3+0.96 ml/min/mmHg/L, n=8)per forearm volume at high intensities(3kg) during early menses. During the proliferaive phase the MetS group increased conductance (6.6×10^−3+0.53×10^−3 mL/min/mmHg/L) at high intensity. Thus metabolically compromised women have reduced vascular conductance which is improved by estrogen. Supported by NM‐INBRE P20RR016480, P20GM103451
GAL‐021 increases CO2‐chemosensitivity at doses that do not stimulate minute ventilation
Authors: Baby Santhosh Mukadiyil , Golder Francis John , Kennedy Andrew Peter , Peng Sean , McIntyre D. Euan
Published: June 2021

GAL‐021 is a novel chemical entity that inhibits BK channels on carotid body glomus type 1 cells and dose‐dependently stimulates ventilation in mice, rats, non‐human primates, and healthy human subjects. As such, GAL‐021 is being developed as a new therapeutic agent to reverse opioid‐induced respiratory depression (OIRD) in people. Here, we evaluated the effects of GAL‐021 on CO2 chemosensitivity at non‐stimulatory plasma concentrations. Minute ventilation was measured using direct tracheal spirometry from urethane‐anesthetized adult rats at three different levels of PaCO2 – baseline, and two levels of hypercapnia: +10 and +20 mmHg above baseline. The slope of the hypercapnic ventilatory responses (HcVR) represented CO2 chemosensitivity. HcVR and CO2 chemosensitivity were measured in each animal before and again during a constant intravenous infusion of GAL‐021, where the dose was titrated in each animal to remain below the threshold that stimulates baseline ventilation. The magnitude of each HcVR and CO2 chemosensitivity was significantly increased during GAL‐021 infusion compared to vehicle control (p<0.001). CO2 chemosensitivity did not change in a time control cohort that received vehicle infusion. Thus, GAL‐021 enhances CO2 chemosensitivity at plasma exposures that do not stimulate baseline breathing. These results suggest that GAL‐021 may have utility as preventative treatment for OIRD and also in the treatment of breathing disorders characterized by intermittent central apneas, such as sleep disordered breathing.
AQP2 poly‐phosphorylation and water permeability in inner medullary collecting duct (IMCD)
Authors: Miranda C.A. , Lee J.W. , Chou C.L. , Knepper M.A.
Published: June 2021

Using mass spectrometry, we previously identified a polyphosphorylated region in aquaporin‐2 (AQP2). Four phosphorylation sites changed with vasopressin: increased S256, S264, S269; decreased S261. To relate these changes to water permeability responses in IMCD (maximal at 0.1 nM arginine vasopressin [AVP]), we carried out dose‐response immunoblotting studies in isolated IMCD suspensions using phosphospecific antibodies. Phosphorylation at S256, S264, and S269 increased progressively with AVP concentrations to 1–2 orders of magnitude above 0.1 nM. Thus, factors other than extent of phosphorylation limit the water permeability response at high AVP. We tested effects of V2 receptor antagonist Tolvaptan in the presence of 1 nM AVP. At the lowest dose (10 nM), Tolvaptan decreased AQP2 phosphorylation at S256, S264 and S269 nearly to levels seen in the absence of vasopressin, and increased phosphorylated S261. (Tolvaptan did not affect AQP2 phosphorylation in the absence of AVP indicating lack of partial agonism.) Thus, although all four AQP2 phosphorylation sites change in response to V2 receptor occupation, measurement of phosphorylation cannot be considered a surrogate for water permeability response. (C.A.M. supported by NIH Medical Research Scholars Program)
Enhanced cardiac KATP channel activity after acclimation to hypoxia in goldfish (Carassius auratus L.)
Authors: DeWitt Judy Park , Ngo Thanh Thu , Chan Stefanie , Cameron John S.
Published: June 2021

Freshwater fishes of the genus Carassius are known for their capacity to survive environmental hypoxia. Further, individual animals may exhibit enhanced tolerance of low oxygen in response to prior acclimation. It has been suggested that the hypoxia‐induced activation of ATP‐sensitive potassium (KATP) channels in critical tissues serves a protective role, increasing tolerance of low oxygen. In goldfish, we have previously shown that mRNA transcription of genes relevant to cardiac KATP channel structure and regulation are altered in response to acclimation under moderately hypoxic conditions (2.6 mg O2/l for seven days at 22°C). In the present study, we used standard intracellular and patch clamp recording techniques to investigate the possibility that this altered transcription is accompanied by functional changes that increase overall KATP channels activity. Intracellular action potential duration in excised ventricles from hypoxia‐acclimated animals was significantly (p<0.05) reduced at both 50% and 90% of full repolarization relative to those from normoxia‐acclimated fish. In cell‐attached ventricular membrane patches from hypoxia‐acclimated goldfish, sarcolemmal KATP channel open probability (NPo) was significantly (p<0.05) enhanced vs. control. These data indicate that prior whole‐animal acclimation to moderate hypoxia enhances overall cardiac KATP channel activity in this species.
Motor unit number estimates in world‐class masters athletes: is 80 the new 60?
Authors: Allen Matti Douglas , Power Geoff A , Filion Maire Eve , Doherty Timothy J , Rice Charles L , Taivassalo Tanja , Hepple Russell T
Published: June 2021

Despite age‐related loss of functioning motor units (MU), masters athletes (MA) in their 7th decade of life retained more MUs than recreationally active controls in the tibialis anterior (TA). It is unknown whether MAs beyond the 7th decade would show similar results. The purpose was to estimate the number of functioning MUs (MUNE) in world‐class, older male (n=4; 80 ± 5 y) and female (n=4; 80 ± 8 y) MAs ranging from 75 to 93 y. A maximal compound muscle action potential (CMAP) was recorded from the TA. Decomposition‐enhanced spike‐triggered averaging was used to analyze surface and intramuscular EMG from the TA during voluntary dorsiflexion contractions in order to derive a MUNE. For both sexes, CMAP was ~43% greater than previously reported in age‐matched normative data in males (6.7 ± 0.9 vs 4.7 ± 1.0 mV) (McNeil et al 2005), which may suggest a maintenance of excitable muscle mass in MAs. Mean surface MU potential (SMUP) size was similar between female MAs (64.3 ± 8.1 μV ) and normative data (78.2 ± 19.3 μV ), whereas male MAs had greater SMUP size than either group (138.0 ± 58.5 μV ). The resultant MUNE for female and male MAs was 100 ± 9 and 55 ± 24 MUs, respectively (p<0.05), with females but not males being higher than age norms. These preliminary results may indicate a sex‐specific protection of MUs in elite MAs >; 75 y of age, where MAs of both sexes may better maintain excitable muscle mass with aging.

Supported by: CIHR (MOP 84408 to T.T.)
The influence of satellite cell‐depletion on glycosaminoglycan accumulation in aged skeletal muscle
Authors: Hardyniec Zakkary James , Lee Jonah D , Peterson Charlotte A.
Published: June 2021

We utilized the Pax7‐DTA mouse model to directly test the role of satellite cells in aged muscle fibrosis. The Pax7‐DTA mouse allows for the conditional depletion of satellite cells in adult muscle with tamoxifen treatment. Four month old mice were treated with tamoxifen or vehicle and sacrificed at 24 months of age. Pax7 immunohistochemistry of the gastrocnemius muscle demonstrated a reduction of 78% of the satellite cell pool in tamoxifen‐compared to vehicle‐treated aged mice. Thus, early‐adulthood tamoxifen treatment successfully reduces the satellite cell pool, which does not effectively recover during the course of the lifespan. Alpha‐wheat germ agglutinin immunostaining demonstrated a 40% increase in glycosaminoglycan expression from muscle depleted of satellite cells, with no differences in muscle cross‐sectional area compared to muscle from vehicle‐treated muscle. The robust increase in glycosaminoglycan expression in satellite cell depleted muscle provides strong evidence that satellite cells participate in the regulation of muscle extracellular matrix remodeling with age, however do not influence overall muscle size.

Funding: NIH R01AR060701 and R21AG34453 (CAP); Ellison Foundation/American Federation of Aging Research EPD12102 (JDL); American Physiological Society undergraduate research fellowship (ZJH); University of Kentucky Center for Muscle Biology.
Effects of hydrogen ion and inorganic phosphate on calcium sensitivity in rat slow muscle fibers
Authors: Nelson Cassandra Rae , Fitts Robert H
Published: June 2021

Intense exercise induces high rates of glycolysis and ATP hydrolysis increasing inorganic phosphate (Pi), H+ and ADP, factors thought to induce muscle fatigue by interfering with the cross bridge cycle. To assess the combined effects of H+ and Pi on calcium sensitivity, stiffness, and rate of force development (ktr) at low (15°C) and high (30°C) temperatures, rat soleus fibers were activated with varied pCa's under control (pH 7.0, 0mM Pi) and fatigue (pH 6.2, 30mM Pi) conditions. At 30°C, fatigue conditions shifted the pCa‐force curve 1.53 units to the right which was greater than the shift induced by either metabolite alone. In fatigue conditions at 15°C, stiffness and force peaked at pCa 5.3 and 4.5, respectively, while at 30°C these values were 5.2 and 5.0. The observation that stiffness and force have similar Ca2+ sensitivities at 30°C is likely the result of an accelerated low‐to high‐force transition (k+1). Fatigue conditions increased ktr at 15°C (2.25 ± 0.8 vs. 3.75 ± 0.5 s−1) but depressed ktr at 30°C (63.8 ± 10 vs. 41.7 ± 8 s−1). The latter was attributed to increased k+1. In summary, the combined effects of high H+ and Pi can be explained by individual effects of these metabolites on the forward and reverse rate constants of force generation. Supported by Marquette University Way Klinger Fellowship.
Improvements in aerobic fitness but not mitochondrial content are intensity dependent in overweight men
Authors: Boyd John Colin , Simpson Craig A , Jung Mary E , Gurd Brendon J
Published: June 2021

The objective of this research was to determine the impact of the intensity of interval training on aerobic fitness, exercise performance, and skeletal muscle oxidative capacity in overweight young adults. 19 sedentary males (Age, 22.7 ± 3.9 yrs; BMI, 31.4 ± 2.6 kg/m2; WC, 106.5 ± 6.6 cm) participated in 9 sessions of interval training at either 70% (LO) or 100% (HI) peak work rate over a three week period. Increases in VO2 peak were greater (p<0.05) following HI (+27.9 ± 13.1%) than LO (+10.4 ± 22.0%) interval training. Performance on a time to completion trial also improved to a greater extent (p<0.05) following HI (+14.1 ± 4.3%) than LO (+8.6 ± 7.6%) training. Oxidative capacity improved in both groups with significant training effects (p<0.05) observed for COX I and COX IV protein content as well as citrate synthase maximal activity. βHAD maximal activity also tended to be higher following training (p = 0.07). No differences were observed between groups for any of the markers of oxidative capacity examined. These findings suggest that improvements in aerobic capacity and exercise performance may be sensitive to the intensity of interval training, while adaptations in skeletal muscle oxidative capacity may not. This research was supported by funding from NSERC.
Abnormal fiber type specification in dystroglycanopathy skeletal muscle
Authors: Beedle Aaron M , Melick Garrett A
Published: June 2021

FKTN is one of eight causative genes for secondary dystroglycanopathy‐type muscular dystrophies. In these disorders, alpha‐dystroglycan lacks sugar structures essential for its binding to extracellular matrix proteins, leading to progressive muscle weakness and wasting, with variable involvement of the brain, eyes, and heart. There is evidence of abnormal muscle development or regeneration/differentiation in both FKTN‐deficient patients and conditional Fktn knockout mice. Therefore, the objective of our study is to determine muscle fiber differentiation patterns in conditional Fktn knockout versus littermate mice. With histological analyses in naïve and regenerating muscle, we find that the nature and timing of fiber type specification is different in young Fktn knockouts compared to littermates. Our data suggest that dystroglycan deficiency in skeletal muscle alters muscle specification of myosin heavy chain isoforms. Future studies are necessary to determine whether fiber type switching is pathogenic or compensatory, and the extent to which altered fiber types redirect the metabolic profile of dystroglycanopathy muscle.

Research supported by the University of Georgia, College of Pharmacy.
IDENTIFICATION OF THE ATP SENSITIVE POTASSIUM CHANNEL ISOLATED FROM MAMMAL AND AVIAN SKELETAL MUSCLE
Authors: Urincho‐Castro Jesús , Manzo‐Ávalos Salvador , Sánchez‐Duarte Elizabeth , Trujillo Xóchitl , Huerta Miguel , Saavedra‐Molina Alfredo , Montoya‐Pérez Rocío
Published: June 2021

The ATP sensitive potassium channels are heteromultimers (octameric complexes) of two types of subunits, the inward rectifier potassium channel (Kir6.x) and the sulfonylureas receptor (SUR). It has been shown that mitochondrial ATP sensitive potassium channel (mitoKATP) plays an important role in protecting muscle during fatigue. The molecular composition of the mitoKATP channel has been the focus of several studies and the results have been controversial, mainly in the type of the rectifier channel, so the goal this study was to identify by Western blot the structural composition of mitoKATP channels from both mammalian and avian skeletal muscle. A previous result shows the presence of the subunit Kir 6.1 and Kir 6.2 in both types of tissues. However more experiments are needed to determine what subunit is more abundant.
Total circulating levels of adiponectin vs transcript abundance in omental fat following the MIQE guidelines in a group of morbidly obese patients
Authors: Mobula Ambie Zanga , Alley Joshua , Samy Sanjay , Fitzgerald Laura , Ariza Magnolia
Published: June 2021

Obesity has a major role to play in multiple metabolic disorders including high blood pressure, type 2 diabetes and even cancer. Adiponectin is a peptide hormone expressed in omental adipose tissues. The goal of this study is to measure how adiponectin transcript abundance in omental fat compares to total circulating levels in circulation. The assays are performed in a group of patients presented with extreme excess weight that correspond to IRB approved clinical trial GHS # 1207–27. The expression of adiponectin is assessed following the minimum information for publication of quantitative real‐time PCR experiments (MIQE) guidelines which outline the minimum information that is essential in the evaluation of qPCR assays, increasing reliability, transparency and integrity of the experiments. Adiponectin transcript abundance is measured in RNA extracted from omental fat, followed by first strand cDNA synthesis using both oligodT and random primers. Target adiponectin and reference beta‐hemoglobin and/or GAPDH transcripts are amplified using SYBR Green. Total serum adiponectin is quantified using enzyme‐linked immunosorbent commercial assay. Both expressed and circulating levels of adiponectin are compared to metabolic clinical parameters. Funding Cornell University Center on the Microenvironment and Metastasis (CMM) outreach pilot grant and Guthrie Foundation Investigator‐Initiated Research Grant.
Hypothalamic mTOR pathway mediates neuronal actions of insulin
Authors: Muta Kenjiro , Morgan Donald A. , Rahmouni Kamal
Published: June 2021

Insulin action in the mediobasal hypothalamus (MBH) influences energy balance and sympathetic nerve activity (SNA). Recently, hypothalamic mechanistic target of rapamycin (mTOR) has emerged as a critical regulator of energy homeostasis and SNA. Here, we tested the importance of mTOR pathway in mediating the hypothalamic actions of insulin. In hypothalamic neuron GT1–7, we found that insulin significantly activated mTOR pathway as indicated by 1.5 and 1.4‐fold change in phosphorylated S6K and S6, respectively. Importantly, pre‐treatment with an mTOR inhibitor, rapamycin (RAP), abolished the activation of S6K and S6. In mice, intracerebroventricular (ICV) administration of insulin activated mTOR pathway in MBH (3.6‐fold increase in S6 phosphorylation), whereas ICV RAP pre‐treatment blunted this effect. Finally, we tested the physiological significance of hypothalamic mTOR activation by insulin in mice. ICV RAP reversed (P<0.05) the anorectic and body weight‐reducing effects of ICV insulin. Similarly, pre‐treatment with ICV RAP attenuated (P<0.05) insulin‐induced increase in SNA to brown adipose tissue, hindlimb and kidney. These results demonstrate that hypothalamic mTOR pathway is critically involved in insulin receptor signaling in MBH and regulation of physiological processes by central action of insulin.
Alleviative effect of andrographolide on alpha‐naphthylisothiocyanate‐induced cholestatic liver injury in rats
Authors: Khamphaya Tanaporn , Piyachaturawat Pawinee , Weerachayaphorn Jittima
Published: June 2021

Cholestasis causes hepatic accumulation of bile acids leading to liver injury, fibrosis and liver failure. Andrographolide, the major active compound isolated from Andrographis paniculata, which is an indigenous plant and has been extensively used for liver diseases in Southeast Asia. However, the hepatoprotective effect on cholestasis has not been investigated yet. We administered andrographolide to rats for 2 days prior to alpha‐naphthylisothiocyanate (ANIT) injection for 2 days. Andrographolide pretreatment reduced ANIT‐induced increases serum aminotransferases, bilirubin, alkaline phosphates and gamma‐glutamyl transpeptidase. Histology of andrographolide administered to ANIT‐injected rats revealed less severe liver inflammation and bile duct proliferation than that in ANIT‐injected rats. In addition, andrographolide decreased the expression of tumor necrosis factor and monocyte chemoattractant protein‐1 in the ANIT‐injected rats. The protein expression of NF‐kB was also suppressed by andrographolide in the ANIT‐treated group. These findings indicated that andrographolide ameliorates cholestatic liver damage. The potential therapeutic action of andrographolide seems to be related to the inhibition of NF‐kB signaling. (This work was supported by Science Achievement Scholarship of Thailand (to T.K.))
The G Protein‐coupled bile acid receptor, TGR5, is expressed on colonic epithelial cells and regulates ion transport
Authors: Ward Joseph Bernard Jude , Mróz Magdalena Slawa , Keely Stephen J
Published: June 2021

TGR5 has been implicated in the regulation of intestinal motility and has also been identified as a regulator of Cl− secretion across gallbladder epithelium. However, there is a paucity of information regarding the role of TGR5 in colonic epithelial cells (CECs). Here we sought to investigate a potential role for TGR5 in regulation of CEC ion transport.

6α‐ethyl‐23(S)‐methylcholic acid (INT‐777) was used to activate TGR5. Ion transport was measured by short‐circuit current (Isc) across muscle‐stripped segments of rat colon. mRNA expression was measured by RT‐PCR. TGR5 localisation was measured by confocal microscopy.

TGR5 mRNA and protein were highly expressed in CECs. TGR5 was localised bilaterally in rat colonic crypts. INT‐777 addition to rat colonic mucosa caused a rapid and transient decrease in Isc. This decrease was dependent on the presence of Cl− in the bathing solution. INT‐777 was effective from the basolateral side only. Furthermore, treatment with INT‐777 reduced subsequent Clsecretory responses to carbachol.

These studies reveal a novel role for TGR5 in regulating colonic epithelial ion transport. TGR5 activation rapidly reduces basal Isc and inhibits subsequent Cl− secretory responses. Our data suggest that TGR5 may provide a new target for development of drugs to treat intestinal transport disorders.

INT‐777 was supplied by Intercept Pharmaceuticals.

Funded by Science Foundation Ireland.
Effects of a (pro)renin receptor blocker on weight gain in obese mice
Authors: Tan Paul , Shamansurova Zulaykho , Michel Catherine , Nguyen Thi , Schiller Peter , Gutkowska Jolanta , Lavoie Julie
Published: June 2021

Objective

Elucidate the role of the (pro)renin receptor [(P)RR] in obesity using a mouse model.

Methods

Mice were fed with a normal (N) or high‐fat/high carbohydrate (HF/HC) diet and treated with saline or a (P)RR blocker [(P)RRB] for 10 weeks. At sacrifice, white adipose tissue (WAT) [subcutaneous fat (SCF), perirenal fat (PRF), perigonadal fat (PGF)] were collected. mRNA was assessed by real‐time PCR, proteins by Western Blot and circulating proteins by array.

Results

(P)RRB decreased weight gain only in mice receiving a HF/HC diet compared to the saline group. (P)RR and renin mRNA in all WAT were increased with obesity compared to N diet without any effect of the (P)RRB with the exception of the SCF where (P)RR was decreased. (P)RR protein increased similarly to mRNA expression with obesity in PRF and SCF but was unaffected by the (P)RRB. Leptin and mesoderm‐specific transcript/paternally expressed gene 1 (MEST/PEG1), a marker of adipocyte cell size, mRNA increased with obesity in all WAT and decreased with (P)RRB on both diets. A similar effect was observed for resistin mRNA in SCF. Circulating leptin was modified similarly as its mRNA while circulating resistin was increased with obesity with no effect of the (P)RRB.

Conclusion

Obesity modulates (P)RR in WAT. (P)RRB seems to decrease weight gain, leptin mRNA and circulating level as well as adipocyte size.
Adiponectin Restores Diabetic Heart Sensitivity to Ischemic Posctconditioning: Role of STAT3 Activation
Authors: Li Haobo , Wang Tingting , Lei Shaoqing , Ng Kwok‐fu , Irwin Michael , Xu Aimin , Xia Zhengyuan
Published: June 2021

Diabetic hearts are prone to ischemia reperfusion (IR) injury and not sensitivity to ischemic postconditioning (IPostC) cardioprotection, and the mechanism is unclear. Adiponectin (APN) confers cardioprotection in non‐diabetes by activating STAT3 (pSTAT3), a key protein in mediating IPostC protection. In diabetic heart, APN is decreased, together with reduced pSTAT3. We hypothesized APN may activate STAT3 in diabetic heart and restore its sensitivity to IPostC. Control (C) and Streptozotocin induced diabetic (D) rats were subjected to 30 min coronary artery ligation followed by 2 hours of reperfusion, without or with IPostC achieved by 3 episodes of 10s reperfusion and 10s re‐occlusion at the onset of reperfusion. Rat was injected with APN (1×109pfu) 7 days before inducing IR. Cardiac functions were assessed by pressure volume (PV) conductance system. Post‐ischemic myocardial infarct size was higher in D relative to C, together with significant reduction of cardiac pSTAT3 and reduction of end systolic PV relation,a reliable measure of ventricular systolic function, in D rats. All these changes in D were reverted by IPostC in the presence but not in the absence of APN (P<0.05 vs. D+APN+IPostC vs. D or D+APN), and abolished by AG490 (which inhibits STAT3 activation). It is concluded that APN restores diabetic heart sensitivity to IPostC by activating STAT3.

Supported by RGC/GRF (784011, 768211), NSFC (81270899)
Evaluation of hypoglycemic and anti –diabetic activity of poly‐herbal formulation in normal and streptozotocin induced diabetic rats
Authors: Sabbani Vidya , Alluri Ramesh , Satla Shobharani
Published: June 2021

The present study was focused to evaluate the hypoglycemic and antidiabetic activity of Maddi Dicare the poly ‐herbal formulation, in both normal and experimentally induced hyperglycemic (Streptozotocin ) rats. Different doses of poly herbal formulation (50, 100 and 200 mg/kg) was administered in rats orally. At the end of the treatment period, the serum from normal and diabetic animals was subjected to the estimation of blood sugar, using glucose kits. Effect of Polyherbal formulation on glucose tolerance was also carried out. It was found to produce significant hypoglycemic activity in both normal and diabetic animals, which could be compared to glibenclamide (10 mg/kg). The Poly‐herbal formulation was found to increase the glucose tolerance in normal rats. The present study demonstrates that herbal formulation exhibits promising anti‐diabetic activity and helps to maintain good glycemic and metabolic control. It also proved hypoglycemic and antidiabetic activity in a dose dependent manner.
SN79, a sigma receptor ligand, mitigates methamphetamine‐induced astrocyte and microglial activation
Authors: Robson Matthew James , Turner Ryan C. , Naser Zachary J. , Huber Jason D. , McCurdy Christopher R. , Matsumoto Rae R.
Published: June 2021

Chronic methamphetamine (METH) exposure results in striatal neurotoxicity (reductions in monoamines and transporters) which can be prevented by sigma (σ) receptor antagonists. METH also activates astrocytes and microglia in the striatum, an effect implicated in its neurotoxic actions. σ receptors are expressed in glial cells and initial microarray analysis revealed σ receptor antagonist modulation of METH‐induced glial activation. The purpose of the current study was therefore, to determine if the putative σ receptor antagonist SN79 mitigates METH‐induced reactive gliosis and neuronal degeneration in the striatum. Male, Swiss Webster mice, quantitative real‐time PCR and immunohistochemistry were used to study striatal gene and protein expression changes related to astrocyte and microglial activation. METH treatment increased striatal gfap mRNA expression and morphologic activation of striatal astrocytes. METH also increased IBA‐1 and CD68 mRNA and protein expression, indicative of microglial activation. SN79 pretreatment attenuated METH‐induced activation of astrocytes and microglia in the striatum. Additionally, SN79 blocked METH‐induced neuronal degeneration as measured by Flouro‐Jade B staining. The current study demonstrates that σ receptor antagonism mitigates METH‐induced reactive gliosis and neuronal degeneration in the striatum. [Funding: DA013978, DA023205]
Role of gastrin‐releasing peptide and neuromedin B receptors in the neurotransmission of itch in the spinal cord of mice
Authors: Sukhtankar Devki , Ko Mei‐chuan
Published: June 2021

Bombesin is a pruritogen which, when centrally administered, causes intense scratching across several animal species. Bombesin has high affinity for receptors of gastrin‐releasing peptide (GRPr) and neuromedin B (NMBr). Studies from GRPr mutant mice and ablated GRPr neurons propose that spinal GRPr are central mediators regulating itch. However, at supraspinal sites, GRPr and NMBr independently mediate scratching behaviors in rats. It is not known to what degree spinal GRPr selectively or generally regulate scratching behavior in mice. To determine if spinal GRPr mediate scratching induced by bombesin‐like ligands, mice were injected with bombesin (0.01–0.3nmol), GRP (0.01–0.3nmol) or NMB (0.1–1nmol) intrathecally by lumbar puncture and were observed for one hour. Bombesin induced most profound scratching that lasted an entire hour while NMB elicited least scratching for a short duration of 15 min. Pretreatment (10 min) with intrathecal injection of a GRPr antagonist RC‐3095 (0.03–0.1 nmol) produced rightward parallel shift in the dose response curve of GRP‐induced scratching but did not diminish bombesin‐or NMB‐induced scratching. Hence, these pharmacological data indicate that the spinal GRPr is only one of the central itch mediators and that there are additional non‐GRPr in the mouse spinal cord regulating neurotransmission of itch (Supported by NIAMS‐R01‐AR059193).
Regulation and Function of CYP2B6 in A CYP2A13/2B6/2F1‐transgenic Mouse Model
Authors: Liu Zhihua , Li Lei , Wu Hong , Ding Xinxin
Published: June 2021

In CYP2A13/2B6/2F1‐transgenic (TG) mice, the tissue distribution of CYP2B6 transgene expression agreed with the known hepatic expression of CYP2B6 in humans (Wei et al., Drug Metab. Dispos. 40:1144–1150, 2012). The aim of this study is to further characterize the expression and function of CYP2B6 in the TG mouse. We examined inducibility of the CYP2B6 transgene by phenobarbital (PB) and dexamethasone (DEX), known inducers of CYP2B6 in human liver. Expression of CYP2B6 mRNA and protein was dramatically induced by both PB and DEX (80 mg/kg/day, i.p. for three days) in the liver, but not in other tissues examined, including lung, brain, small intestine, and kidney, where CYP2B6 protein was undetected. To determine whether the transgenic CYP2B6 is functional, we studied a CYP2B6‐humanized (TG/Cyp2abfgs‐null) mouse, generated by intercrossing between TG mice and newly generated Cyp2abfgsnull mice. We found that the rates of cotinine formation from nicotine in hepatic microsomes of the TG/Cyp2abfgs‐null mice were significantly higher than those in Cyp2abfgs‐null mice, either before or after CYP2B6 induction by DEX. These results indicate that the transgenic CYP2B6 is functional, and its expression in the liver can be induced by known CYP2B6 inducers. The TG/Cyp2abfgs‐null mouse is thus a useful in vivo model to study functional consequences of hepatic CYP2B6 expression/induction on drug metabolism and toxicity.
Regulation of MOR‐1A, an intron‐retention splice variant of the mu opioid receptor (OPRM1) gene, by miR‐107
Authors: Lu Zhigang , Xu Jin , Xu Mingming , Pasternak Gavril W , Pan Ying‐Xian
Published: June 2021

The mu opioid receptor (OPRM1) gene undergoes extensive alternative splicing, generating an array of splice variants. Of these variants, MOR‐1A was quite abundant and conserved from rodent to humans. Loss of splicing from exon 3a to its downstream exons leads to the intron retention, producing MOR‐1A. Several miRNAs have been indicated to regulate expression of the original mu opioid receptor, MOR‐1. However, there has been a lack of studies on miRNA regulation of the OPRM1 splice variants. In the present study, we report identification of complete 3′UTR for both mouse and human MOR‐1A, and regulation of MOR‐1A expression by miR‐107 through a target site within the 3′UTRs. Using a 3′RACE approach, we first identified a polyadenylation site for both mouse and human MOR‐1A, which was further confirmed by Northern blot analyses. We then identified a conserved miR‐107 targeting site in the 3′UTR of both mMOR‐1A and hMOR‐1through several computer models including miRBase, Targetscan and RNAhybrid. The functional relevance of the miR‐107 targeting sites was verified by using luciferase‐based reporter system combined with miR‐107 inhibitor in HEK293 cells, as well as Be(2)C cells that endogenously express hMOR‐1A. Our results also indicated that miR‐107 regulated expression of mMOR‐1A or hMOR‐1A mainly at translation level.

Supported by DA13997/DA029244 (YXP) and DA02615/DA07242 (GWP) from NIDA.
The Senescence‐associated Secretome of Fat Cells Drives Inflammation and Insulin Resistance and Inhibits the Proliferation of Human Skeletal Muscle Cells
Authors: White Thomas A , Giorgadze Nino , Zhu Yi , James Kirkland L , Tchkonia Tamara , LeBrasseur Nathan K
Published: June 2021

Infiltration of fat cells into skeletal muscle is a hallmark of aging that has been associated with insulin resistance and the pathogenesis of type 2 diabetes mellitus (T2DM). The mechanisms by which fat cells affect the health and metabolic state of skeletal muscle are poorly understood. Given the evidence for cross‐talk between these tissues and the secretory phenotype of senescent preadipocytes, we first utilized real time‐PCR to examine the expression of inflammatory cytokines in primary human skeletal muscle‐derived cells (SkMDCs) in response to conditioned medium (CM) from either control human preadipocytes (Normal CM) or from human preadipocytes driven to senescence by irradiation (Senescent CM). Exposure of SkMDCs to either Normal CM or Senescent CM for 24 hours significantly increased their expression of IL‐6 (5.1±1.7‐and 14.1±4.7‐fold, respectively), TNFα (1.3±0.2‐and 2.1±0.67‐fold, respectively) and MCP‐1 (2.9±1.1‐and 6.8±2.3‐fold, respectively). Next, we investigated the effects of CM on insulin signaling in SkMDCs via Western blot analysis. Exposure of SKMDCs to preadipocyte CM significantly blunted insulin‐stimulated phosphorylation of its downstream effectors, including Akt (14–24%, p<0.05). Finally, we examined the effects of CM on the proliferative capacity of undifferentiated SkMDCs. Senescent CM inhibited SkMDC proliferation by more than 30% (p < 0.05). In conclusion, factors secreted by preadipocytes, and in particular, senescent preadipocytes, negatively impact the inflammatory and metabolic phenotype and the proliferative capacity of skeletal muscle cells. Elucidation of the biologic materials that are secreted from fat cells and mediate these effects may lead to novel therapeutic strategies for the treatment of age‐related conditions, including T2DM. The authors acknowledge the support of Mayo Clinic and a generous gift from Robert and Arlene Kogod.
Effect of exogenous leptin on thrombotic and metabolic profiles of FVB/B6 lipodystrophic mice
Authors: Kadouh Hoda C. , Yang Soo Jin , IglayReger Heidi B. , Bodary Peter F.
Published: June 2021

The adipokine leptin appears to play a pro‐thrombotic role in mice, a function that has not been examined in lipodystrophic animals. This study was designed to examine the thrombotic and metabolic effects of leptin administration in a mouse model of lipodystrophy. Eight‐week‐old, male FVB(AZIP/F1)/B6 mice (Transgenic, Tg and Wild‐type, Wt) received recombinant mouse leptin (Tg‐T, n=4; Wt‐T, n=4) or vehicle (Tg‐C, n=3; Wt‐C, n=5) via osmotic pumps over 12 days. Tg mice had a prolonged time to occlusive thrombosis compared to Wt mice (p<0.05), and leptin therapy had no effect on this trait. At baseline/control, Tg mice were heavier than Wt mice (p<0.05), had larger livers (p<0.0001), higher serum insulin (p<0.01) and plasma and liver triglyceride (p<0.01 and p<0.05, respectively), and undetectable leptin (p<0.0001). Tg‐T mice lost weight (p<0.05) and had smaller livers (p<0.05), higher leptin levels (p=0.01) and reduced insulin levels (p<0.05), compared to Tg‐C mice. Elevated HOMA‐IR scores in Tg‐C mice (p<0.05) verified insulin resistance, ameliorated by leptin therapy. These findings confirm the hepatomegaly, insulin resistance and hyperlipidemia seen in lipodystrophic mice and the effectiveness of leptin therapy while also suggesting that lipodystrophy, at least in the AZIP/F1 mouse, exerts an anti‐thrombotic phenotype independent of the lack of leptin. Funding source: American Diabetes Association.
Quantitative Prediction of Impact of Left Ventricular Assist Device (LVAD) on Hemodynamics
Authors: Kakino Takamori , Saku Keita , Sakamoto Takafumi , Sakamoto Kazuo , Akashi Takuya , Tobushi Tomoyuki , Murayama Yoshinori , Fujino Takeo , Onitsuka Ken , Ikeda Masataka , Oga Yasuhiro , Nishizaki Akiko , Kuwabara Yukimitsu , Ide Tomomi , Sunagawa Kenji
Published: June 2021

Background

Although LVAD has been saving many lives in patients with end stage heart failure, the quantitative prediction of LVAD on hemodynamics remains to be established.

Theoretical analysis

We developed a framework of circulatory equilibrium where the cardiac output (CO) curve and venous return surface (VRS) were expressed as the function of right (PRA) and left atrial pressure (PLA). The CO curve is algebraically derived using the concept of ventricular arterial (VA) elastance coupling. Incorporating LVAD into the VA coupling indicates that LVAD support (COVAD) increases left ventricular (LV) afterload and decreases native CO (COLV). The total CO (COtotal) becomes COtotal=COLV+COVADEFe where EFe approximates ejection fraction. In contrast, LVAD does not change the VRS or right ventricular CO curve. Equilibrating the COtotal curve and VRS yields CO, PRA and PLA.

Methods/Results

In 6 anesthetized, vagotomized dogs, we isolated the carotid sinuses to abolish baroreflex. We ligated coronary arteries to create LV failure and inserted LVAD. We changed COVAD stepwise from 0 to 100 ml/kg/min and predicted COtotal, PLA and PRA in each LVAD support. As shown, predicted COtotal, PLA and PRA quantitatively matched well with those measured.

Conclusion

The proposed framework predicts the impact of LVAD on hemodynamics and thus contributes to the optimal management of patents on LVAD.
Aging exacerbates hypertension‐induced cerebromicrovascular injury in mice: role of autoregulatory dysfunction in the development of vascular cognitive impairment
Authors: Toth Peter , Tucsek Zsuzsanna , Sosnowska Danuta , Gautam Tripti , Mitschelen Matthew , Tarantini Stefano , Deak Ferenc , Koller Akos , Sonntag William E , Csiszar Anna , Ungvari Zoltan
Published: June 2021

Hypertension in the elderly is a main risk factor for vascular cognitive impairment (VCI). To elucidate the mechanisms by which aging exacerbates the deleterious cerebrovascular effects of hypertension, young (3 mo) and aged (24 mo) C57/BL6 mice were infused with angiotensin II (AngII) for 4 weeks. In young hypertensive mice, pressure‐induced myogenic tone of middle cerebral arteries (MCA) was increased (due to an up‐regulation of the 20‐HETE/TRPC6 pathway). MCAs of aged AngII treated mice exhibited impaired functional adaptation to hypertension (decreased myogenic tone, autoregulatory dysfunction), which was associated with increased disruption of the blood‐brain barrier, hippocampal microvascular rarefaction, microglia activation, up‐regulated hippocampal expression of pro‐inflammatory cytokines and chemokines and impaired performance in tests relevant for hippocampally ‐dependent tasks of learning and memory. Taken together, aging exacerbates hypertension‐induced cerebromicrovascular injury in mice due to an age‐related autoregulatory dysfunction, which induces neuroinflammation and promotes the development of VCI.
Platelets activated during myocardial infarction release functional miRNA which can be taken up by endothelial cells and regulate ICAM1 expression
Authors: Gidlof Olof , van der Brug Marcel , Ohman Jenny , Gilje Patrik , Olde Bjorn , Wahlestedt Claes , Erlinge David
Published: June 2021

Activated platelets play a critical role in the pathogenesis of myocardial infarction, adhering to the site of a ruptured atherosclerotic plaque and releasing a multitude of factors affecting the endothelium. MicroRNA is a class of short, non‐coding RNA that acts to repress gene expression. Recent reports have suggested that miRNAs can be transferred between cells and act as paracrine regulators of gene expression. The aim of this study was (1) to screen for differences in miRNA content of platelets from patients with myocardial infarction (MI) and healthy individuals and (2) to elucidate whether platelet miRNAs could be released and act as paracrine regulators of endothelial cell gene expression. We found 9 differentially expressed miRNAs in patients compared to healthy controls, of which 8 were decreased in patients. The levels of miR‐22, ‐185, ‐320b and ‐423–5p increased in the supernatant of platelets after aggregation and were depleted in thrombi aspirated from MI patients. Transfer of both fluorescently labeled miRNA and exogenous cel‐miR‐39 from activated platelets to endothelial cells was shown in vitro. ICAM1 was shown to be a target of miR‐22 and miR‐320b. The effect of platelet releasate on endothelial ICAM1 expression was dependent on miR‐320b. Thus, platelets from STEMI patients exhibit loss of specific miRNA and activated platelets shed miRNAs that can regulate endothelial cell gene expression.