bluuebunny/crossref_metadata_2025 huggingface dataset:
Neuroprotective effects of antioxidants, Idebenone and Ferulic Acid, in MPTP/MPP+ intoxicated PC12 cells as a model of Parkinson's Disease
Authors: Gupta Shilpi , Benzeroual Kenza
Published: June 2021

Evidence suggests that α‐synuclein inclusions and COX‐2 upregulation contribute to mitochondrial dysfunction and neuroinflammation in Parkinson's disease (PD). Increased expression of COX‐2 has been reported to cause dopamine oxidation, which in turn triggers oxidative stress and α‐synuclein accumulation. Other studies also suggest that NF‐κB regulates the expression of neuronal COX‐2 at the genetic level. The present study investigated the protective effect of Idebenone, a synthetic analog of CoQ10, and Ferulic acid, a naturally occurring phenolic compound, against MPTP/MPP+‐induced oxidative stress and neurodegeneration in PC12 cells, used as an in‐vitro model of PD. Results showed that both drugs dose dependently decreased the expression of α‐synuclein, along with a decrease in the expressions of COX‐2 and NF‐κB, as compared to the increase induced by MPTP/MPP+. In addition, the ROS levels and Bax/Bcl‐2 ratio for Idebenone and Ferulic acid significantly decreased as compared to the increased levels seen with the toxin. This suggests that the neuroprotection offered by the two drugs may be anti‐oxidative as well as anti‐apoptotic in nature. The research was supported by Long Island University.
Aged eNOS−/− mice display increased APP expression, microglial activation, and impaired spatial memory
Authors: Austin Susan A. , Santhanam Anantha V. , Hinton David J. , Choi Doo‐Sup , Katusic Zvonimir S.
Published: June 2021

Aging and other cardiovascular risk factors are associated with increased incidence of Alzheimer's disease (AD). A common feature of cardiovascular risk factors is decreased endothelial nitric oxide (NO). We studied the effect of a loss of endothelial NO on amyloid precursor protein (APP) related phenotype in aged (14–15 month) endothelial nitric oxide synthase deficient (eNOS−/−) mice. APP, β‐site APP cleaving enzyme 1, and amyloid beta (Aβ) levels were significantly higher in the brains of aged eNOS−/− mice as compared to aged wild type mice. APP and Aβ1–40 were increased in hippocampal tissue of eNOS−/− mice as compared to wild type mice. Aged eNOS−/− mice displayed an increased inflammatory phenotype as compared to aged wild type mice. Importantly, aged eNOS−/− mice performed worse in a radial arm maze test of spatial learning and memory as compared to aged wild type mice. These data suggest that chronic loss of endothelial NO may be an important contributor to both Aβ related pathology and cognitive decline. Research was supported by NIH grants HL‐111062 and HL‐91867, the Mayo Alzheimer's Disease Research Center (Z.S.K.), AHA scientist development grant (0835436N, A.V.S.), AHA postdoctoral fellowship 12POST8550003 (S.A.A.), Clinical Pharmacology Training Grant (T32 GM08685) (Trainee S.A.A.), the Samuel Johnson Foundation for Genomics of Addiction Program at Mayo Clinic (D.‐S.C.) and the Mayo Foundation.
Hydrogen Sulfide Increases Aqueous Humor Outflow in Porcine Trabecular Meshwork
Authors: Robinson Jenaye Danielle , Njie‐Mbye Ya Fatou , Okpobiri Anita , Chitnis Madhura , Opere Catherine A , Ohia Sunny E
Published: June 2021

We have evidence that the colorless gas, hydrogen sulfide (H2S), can produce pharmacological actions in the eye. In the present study, we tested the hypothesis that the intraocular pressure lowering effect of H2S (using H2S‐releasing compounds as donors) is mediated by an increase in aqueous humor (AH) outflow in porcine trabecular meshwork (TM) tissues.

Methods

Porcine ocular anterior segments explants were perfused with Dulbecco's Modified Eagle's Medium maintained at 37ºC, 5% CO2 and constant pressure of 7.35 mmHg. Once outflow was stable, explants were administered with H2S‐releasing compounds; sodium hydrosulfide (NaHS, 1 nM, 100 nM), L‐cysteine (100 nM), and outflow was monitored for 4 hours. Vehicle (0.1% saline) was run in parallel.

Results

NaHS (1 nM), a fast‐releasing H2S compound significantly increased AH outflow by 38% for only 1 hour when compared to vehicle. Furthermore, there was a concentration‐dependent increase in AH outflow with administration of 1 nM and 100 nM of NaHS. L‐cysteine (100 nM), a slow‐releasing H2S compound caused a significant (p<0.01) increase in outflow facility. Interestingly, the duration of the effects of L‐cysteine on AH outflow lasted longer than that of NaHS.

Conclusion

H2S‐releasing compounds can increase AH outflow in porcine TM indicating a pharmacological role for H2S in the regulation of IOP.
Deficiency of epidermal growth factor receptor prevents angiotensin II‐induced hypertrophy, but not inward remodeling, in cerebral arterioles
Authors: Baumbach Gary L , Gerhold Thomas D
Published: June 2021

We examined the effect of epidermal growth factor receptor (EGFR) deficiency on structural alternations in cerebral arterioles induced by angiotensin II (Ang II). Two month old homozygous (−/−) waved‐2 (Wav2) mice, in which a point mutation impairs autophosphorylation of EGFR, and heterozygous (+/−) Wav2 littermates were infused with Ang II (1000 ng/kg/day) or saline via osmotic minipumps for 28‐days. Systolic arterial pressure (SAP) was measured by a tail‐cuff method. External diameter (ED) of maximally dilated (EDTA) cerebral arterioles was measured in vivo under anesthetized conditions. Cross‐sectional area of the arteriolar wall (CSA) was measured histologically. Ang II increased SAP pressure in Wav2+/− (142±4 vs 115±5 mmHg in saline infused, P<0.05) and Wav2−/− mice (136±6 vs 108±5 mmHg, P<0.05). ED was reduced by Ang II in both Wav2+/− (58±3 vs 69±3 μm, P<0.05) and Wav2−/− (59±3 vs 68±4 μm, P<0.05) mice, whereas CSA was increased in Wav2+/− (518±56 vs 403±35 μm2, P<0.05), but not in Wav2−/− (410±24 vs 419±65 μm2, P<0.05), mice. These findings suggest that transactivation of EGFR may play an important role in Ang II‐induced hypertrophy of cerebral arterioles, but may not in inward remodeling.
Selective dopamine D4 receptor agonist effects and their impact on regression of left ventricular hypertrophy in SH rats
Authors: De Jesus Luis , Giles Ruth , Anoka Albert Prescott Tennyson , de Jesus Gomez Villalobos Ma.
Published: June 2021

Left ventricular hypertrophy is an adaptive response that involve a remodeling in heart tissues, however is associated with increased morbidity and mortality. In this study we characterized the effect of chronic administration of a selective dopamine D4 receptor agonist, the PD 168 099, in the left ventricular hypertrophy (LVH) in spontaneous hypertension rats (SHR). Male spontaneous hypertension rats (SHR), 2 months old, were distributed in 5 experimental groups, for daily drug oral administration during two months (metroprolol 100 mg/kg, losartan 50 mg/kg, bromocriptine 10 mg/kg, and PD 168 099 1 mg/Kg). After two months, systolic arterial blood pressure (SABP) by tail cut off occlusion method was recorder, after animals were sacrificed and hearts extracted, weighed and measured. In the sham groups, SABP, and ratio heart/body weight, were higher; 205±3 mmHg and 0.502±0.21, respectively. All drugs reduced the SABP, however the PD 168 099, was the most effective as losartan in decrease the ratio heart/body weight. Ours results demonstrate that PD 166 099 has a similar effect than losartan on the regression of left ventricular hypertrophy in the SH rats, suggesting that a selective dopamine D4 receptor agonist could be a good alternative as pharmacological treatment in LVH related to hypertension. Support from CONACYT
Coronary artery reactivity is increased in the aged SHR, a model of postmenopausal vascular physiology.
Authors: McCarthy Joseph , Gerevics Rebecca , Ramirez Rolando J.J. , Novak Jacqueline
Published: June 2021

Women have a decreased risk of cardiovascular disease compared to men until after menopause when the risk is similar between men and women. The mechanism for cardioprotective effect is unclear. In order to study the physiological changes which occur in the cardiovascular system of women after menopause it is necessary to identify animal models. One model of post‐menopausal physiology is the aged spontaneously hypertensive female rats (SHR). The endocrine and blood pressure changes have been previously reported by Reckelhoff and colleagues. However, the vascular changes have not been characterized. The purpose of this study was to characterize the vascular behavior of coronary arteries in the aged female SHR. Septal coronary arteries were isolated from old and young SHR and studied in a pressure arteriograph. Active and passive diameters were measured over a range of pressures ranging from 10 to 100mmHg. Percent tone was calculated (1‐(Dactive‐Dpassive)*100%) at each pressure step. At each pressure step from 20–100 mmHg the percent tone was greater in the old SHR (19.8 + 1.5%) compared to young female SHR (7.7+ 0.2%). These results indicate that the aged SHR can be used as a model to study post‐menopausal increases in the coronary vascular reactivity.

Funded by NIH R15HL097343
Phosphodiesterase‐5 activity exerts a coronary vasoconstrictor influence in awake swine that is partly mediated via an increase in endothelin production
Authors: Duncker Dirk J , Zhou Zhichao , de Beer Vincent J , Merkus Daphne
Published: June 2021

Nitric oxide (NO)‐induced coronary vasodilation is mediated through production of cyclic guanosine monophosphate (cGMP), and through inhibition of endothelin (ET). We previously demonstrated that both phosphodiesterase 5 (PDE5) and ET each exert a vasoconstrictor influence on coronary resistance vessels. Here we investigated the integrated control by PDE5 and ET of coronary resistance vessel tone in exercising swine. ETA/ETB receptor blockade with tezosentan (3 mg/kg iv) and PED5 inhibition with EMD360527 (300 μg/kg/min iv) each produced coronary vasodilation at rest that waned with incremental levels of exercise. Interestingly, however, tezosentan failed to produce further coronary vasodilation in the presence of EMD360527. Similarly, tezosentan (10−9–3×10−5 M) and EMD360527 (10−9–3×10−5 M) each produced concentration‐dependent vasodilation in preconstricted isolated porcine coronary small arteries in vitro, while tezosentan again failed to produce additional vasodilation in the presence of EMD360527. Importantly, EMD360527 (3×10−6 M) significantly attenuated Big ET‐induced (10−7 M), but not ET‐induced (10−7 M), coronary small artery constriction. In conclusion, PDE5 activity exerts a vasoconstrictor influence on coronary resistance vessels that is partly mediated via an increase in ET production.
The effects of head‐up and head‐down tilt on cerebrovascular CO2 reactivity in anterior and posterior cerebral circulations
Authors: Day Trevor A , Tymko Michael M , Skow Rachel J
Published: June 2021

Cerebral autoregulation is a protective feature of the cerebrovasculature that maintains relatively constant cerebral perfusion in the face of static and dynamic fluctuations in mean arterial pressure (MAP). However, gravity‐dependent shifts in blood volume distribution during head‐up and head‐down tilt (HUT, HDT) have profound effects on venous return, cardiac output and MAP. Further, cerebral blood flow (CBF) is highly sensitive to the influence of changes in arterial CO2 (PaCO2) on arteriolar diameter. We tested the effects of steady‐state tilt on cerebral blood velocity (CBV) and CO2 reactivity in the middle and posterior cerebral arteries (MCA, PCA) using hyperoxic rebreathing and transcranial Doppler ultrasound in various positions on a tilt table. Following initial testing in supine position, subjects were positioned randomly and tested in each of four positions: 90° HDT, 45° HDT, 45° HUT and 90° HUT. There were no differences in steady‐state MCA or PCA CBV across positions. Absolute and relative CO2 reactivity slopes were calculated for the MCA and PCA using linear regression. Absolute reactivity was greater in the MCA than the PCA in all 5 positions, but there was no interaction between reactivity and tilt. Our data demonstrate that CBF is maintained through cerebral autoregulation in the face of superimposed steady‐state orthostatic stress and dynamic changes in PaCO2.
The mitochondria‐targeting peptide Bendavia protects the heart against ischemia‐reperfusion injury without abolishing ischemic preconditioning
Authors: Stewart Luke M , Lloyd Jacob Q , Patel Hetal D , Moukdar Fatiha , Brown David A
Published: June 2021

Bendavia is a mitochondria‐targeted peptide that protects the heart against ischemia‐reperfusion (I/R) injury in a wide range of experimental models. We have previously shown that Bendavia's mechanism of action involves lowering intracellular levels of reactive oxygen species (ROS). As other compounds that lower ROS levels can abrogate the protective effects of ischemic preconditioning (IPC), this study was conducted to determine if Bendavia influenced the protection evoked by IPC. Isolated guinea pig hearts were put into one of 4 groups: untreated controls (n=7), perfusion with 1nM Bendavia without IPC (n=5), untreated+IPC (n=6), and IPC+1nM Bendavia (n=5). All hearts were exposed to I/R (20/120 min respectively), with cardiac electromechanical function monitored throughout the protocol. Infarct size (expressed as % of zone‐at‐risk; ZAR) was reduced in hearts treated with Bendavia (29 +/− 2.4% ZAR) when compared to untreated hearts (42% +/−2.5 P=<0.01 ). IPC also reduced infarct size to 26 +/−3.3% ZAR, and the protective effect of IPC was not influenced by Bendavia (23 +/− 1.6% ZAR). We conclude that Bendavia may be an attractive candidate for preventing cardiac injury without influencing endogenous protective signaling. Funding for this project included support from the APS UGSRF program.
Role of caveolin‐3 in adenosine‐induced increase in mitochondrial PKCε
Authors: Kang Chen N/A , Hu Keli
Published: June 2021

Activation of adenosine receptors has been shown to promote translocation of PKC isoforms to both caveolar plasma membrane and mitochondria. Adenosine receptors, PKC and caveolin‐3 play important roles in the cardioprotection of ischemic preconditioning. The present study was designed to determine whether adenosine receptor activation‐induced translocation of PKCε to mitochondria is caveolin‐3‐dependent. Immunofluorescence imaging of isolated mitochondria showed that adenosine‐induced increase in mitochondria PKCε was inhibited by adenosine A1 receptor specific inhibitor DPCPX (36.0 ± 1.2% vs. 72.7 ± 1.8% in cardiomyocytes and 19.0 ± 1.0% vs 57.5 ± 2.0% in H9c2 cells, n=3, P<0.01). Neither adenosine A2B receptor specific inhibitor MRS1754 nor PI3K kinase inhibitor Wortmannin prevented adenosine‐induced increase in mitochondrial PKCε. Interestingly, adenosine‐induced mitochondrial translocation of PKCε was significantly reduced by suppressing caveolin‐3 expression with specific siRNA (52.0 ± 2.0% vs. 17.7 ± 2.0%, adenosine vs. adenosine/caveolin‐3‐siRNA in H9c2 cells, n=3, P<0.01), while negative siRNA had no effect. In conclusion, we demonstrate that adenosine receptor activation induces caveolin‐3‐dependent translocation of PKCε to mitochondria. These results point out a novel mechanism in regulating PKC isoform in mitochondria.
Leptin induces adiponectin expression: Implications in obesity
Authors: Singh Prachi , Sahakyan Karine R , Sert‐Kuniyoshi Fatima H , Romero‐Corral Abel , Delacroix Sinny , Davison Diane E , Jensen Michael D , Somers Virend K
Published: June 2021

Background

Expression of adiponectin, an anti‐atherogenic and insulin‐sensitizing adipokine, is decreased in obesity. Mechanisms underlying this reduction are not well understood. Increased adiponectin in obesity may protect against development of cardiac and metabolic disorders.

Objective

To investigate the role of leptin in regulating adiponectin expression in humans.

Design

1) determining the relationship between leptin and adiponectin in healthy humans during modest weight gain; 2) in‐vitro validation of the role of leptin in adiponectin expression.

Results

Modest weight gain of 3.8 ± 1.2 kg over 8 weeks of overfeeding in normal weight healthy subjects (n=33, 22 men, 30±7 years) increased both leptin and adiponectin. Changes in leptin during weight gain correlated with changes in adiponectin (rho=0.35, p=0.045), suggesting that leptin may regulate adiponectin expression. In cultured differentiated human white preadipocytes, leptin increased adiponectin mRNA and protein expression.

Conclusions

Leptin induces adiponectin expression. In obesity, adipose tissue may be resistant to leptin signaling thus preventing increases in adiponectin. Therefore, impaired leptin signaling may contribute to low adiponectin in obesity. Targeting leptin resistance may be beneficial in preventing obesity‐associated cardiac and metabolic disorders.

Support: AHA 11SDG7260046, R21 DK81014
Hemorrhage‐induced Hyperglycemia Improved with Acute TNFα blockade in the Obese Zucker Rat
Authors: Clemmer John , Xiang Lusha , Lu Silu , Mittwede Peter , Hester Robert
Published: June 2021

Post‐hemorrhage hyperglycemia is correlated with increased inflammation and mortality. Obese patients show exacerbated inflammation and complications to severe blood loss. However, whether hemorrhage leads to exaggerated inflammation‐mediated hyperglycemia in obesity has not been examined. We hypothesized that obese Zucker rats (OZ) have exaggerated hyperglycemic responses to hemorrhage and that acutely blocking TNFα will improve glucose responses. Fasted lean Zucker rats (LZ) and OZ were treated with a TNFα antagonist, etanercept (2mg/kg, sq.), (LZE and OZE, respectively), or saline (0.2 ml) 3 hours before hemorrhage. Hemorrhage was induced by withdrawing blood (35% total volume) over 10 minutes. Plasma glucose levels and blood pressure were measured during a 3 hour recovery period. There were no differences among groups in basal glucose levels or blood pressure before and immediately after hemorrhage. However, average glucose levels during the 3 hours after hemorrhage were higher in OZ (459 ± 40 mg/dl) but not OZE (315 ± 18 mg/dl) as compared to LZ (263 ± 24 mg/dl) and LZE (315 ± 42 mg/dl). We conclude that after hemorrhage, OZ exhibits an increased TNFα–mediated hyperglycemia, which could be responsible for the increased vulnerability to hemorrhagic shock seen in obese patients. Supported by NIH HL‐51971, HL‐89581, T32 HL‐105324, AHA‐12SDG12050525
Altered Mitochondrial Morphology Elucidates Cell Death Mechanisms in the Aged Female Rat Heart
Authors: Diaz Carlos , Machikas Alexandra , Ball Richard W , Lopez Veronica , Korzick Donna H
Published: June 2021

Background

Acute myocardial infarction and associated ischemia/reperfusion (I/R) injury remains a leading cause of death in older post‐menopausal women. I/R injury triggers mitochondrial dysfunction leading to necrosis, apoptosis, and/or autophagy.

Purpose

To determine if age‐associated estrogen deficiency alters mitochondrial morphology in conjunction with vulnerability to I/R injury.

Methods

Mitochondrial morphology was assessed through electron microscopy in border zone regions following coronary artery ligation (55 min I and 4–6 hr R) or sham in adult (6 mo) ovary‐intact, aged (24 mo) ovary‐intact and aged ovariectomized (OVX) female F344 rats. Necrosis was assessed by triphenyltetrazolium chloride staining, apoptosis by DNA laddering and TUNEL, and markers of autophagy by western blotting.

Results

Loss of mitochondrial matrix following I/R was greatest in aged OVX. Mitochondrial area was less in aged vs adult in conjunction with increased mitochondrial number and marked Z line streaming. Reduced DNA laddering and TUNEL, combined with increased beclin‐1 and cathepsinD in aged vs adult, further support a dominant role for necrosis underlying cell death in aged females (n=4–5/group).

Conclusion

Morphological alterations in mitochondria with aging are likely contributory in necrotic cell death mechanisms associated with I/R injury in post‐menopausal women.
Cardiac remodeling of intercalated discs in Friedreich's ataxia
Authors: Mazurkiewicz Joseph E. , Ramirez R. Lianne , Koeppen Arnulf H.
Published: June 2021

Friedreich's ataxia (FRDA), an autosomal recessive neurodegenerative disease caused by a defect in the gene for the mitochondrial protein frataxin, also displays cardiac involvement, most commonly as dilated cardiomyopathy and arrhythmia. Progression is related to the amount of residual frataxin and disease duration. Mechanical cardiomyocyte stress is very high in the left ventricular wall and may be responsible for the extensive scarring and remodeling of the myocardium. Such remodeling involves intercalated discs (ICD) that provide for mechanical cohesion between myocardial fibers and for impulse transmission through gap junctions (GJ). Altered distribution of GJ connexins (Cx) may lead to abnormal coupling between cardiomyocytes, contributing to arrhythmogenesis. Immunocytochemistry for N‐cadherin and CX43 were used to examine ICD structure and GJ distribution. In normal myocardium, N‐cadherin‐reactive ICD were distributed along cardiomyocytes at ~ equal distances of 40 μm. Fibers and ICD measured ~ 20 μm in dia. In FRDA, ICD appeared chaotic in their organization across hypertrophic fibers, with some fibers reaching 100 μm dia. “Lateralization” of CX43 in hypertrophic cardiomyocytes was prominent in FRDA. These findings in FRDA are consistent with similar features of cardiac remodeling in other diseases of the human heart. GJ and Cxs are increasingly suggested as potential therapeutic targets.
Distinct calcineurin‐related transgenic approaches rescue or exacerbate the dystrophic phenotype in fibers from crossbred mdx mice despite constant HSP70 expression
Authors: Zein Manal , Jasmin Bernard Jean , Michel Robin Nicholas
Published: June 2021

We have shown the dystrophic phenotype to be rescued by driving the slower oxidative myogenic program via calcineurin/NFAT (Cn/NFAT) signaling together with an increase in utrophin A expression (Chakkalakal et al 2004, 2006). However, a recent study suggests an alternate strategy in the rescue of the dystrophic phenotype by overexpressing HSP70 without necessary changes in utrophin A expression (Gehrig et al 2012). We thus set out to examine HSP70 expression in muscles of dystrophic mdx mice crossbred with mice expressing transgenes (Tg) that manipulate the Cn/NFAT pathway. From WBs we found upregulation of utrophin A driven by the Tg overexpression of Cn and its downregulation after the Tg expression of either parvalbumin or calmodulin binding protein. These changes in utrophin A expression occurred without changes in HSP70 levels, indicating that regulation of these two proteins is not correlated. Further, IF experiments showed a robust and rigid co‐localization of HSP70 with MyHC I in Tg‐modified mdx slow fibers displaying impaired Cn/NFAT signaling together with decreased utrophin A expression and a clear exacerbation of the dystrophic phenotype. These results not only underscore the therapeutic potential of targeting Ca+2/Cn‐based signaling intermediates as effective countermeasures for DMD, but also raise questions to the role of HSP70 in rescuing the dystrophic pathology. Funded by CIHR, NSERC and CRC.
Metabolomic profiling of aging rat skeletal muscle
Authors: Garvey Sean M. , Guo Lining , Kennedy Adam D. , McDunn Jonathan E. , Pereira Suzette L.
Published: June 2021

Skeletal muscles undergo progressive atrophy and pathologic remodeling with age. To better understand muscle senescence, we used metabolomic profiling to characterize ‘adult’ (15‐month‐old; n=8) and ‘old’ (32‐month‐old; n=8) FBN male rats. Gastrocnemius (gastroc) and soleus muscles were analyzed, as well as plasma. Compared to adult gastroc, old gastroc showed evidence of altered glucose metabolism, including accumulation of glycolytic, glycogenolytic, and pentose phosphate pathway intermediates. Pyruvate was elevated with age, yet tricarboxylic acid (TCA) cycle intermediates were reduced, and nicotinamide adenine dinucleotide was reduced 82% (p<0.0001). Indicative of muscle atrophy, 3‐methylhistidine and free amino acids were elevated in old gastroc. The monounsaturated fatty acids oleate, cis‐vaccenate, and palmitoleate, also increased in old gastroc. Old soleus showed reductions in glycolytic and TCA cycle intermediates, and 39% (p<0.0001) reduction in flavin adenine dinucleotide. Age‐related plasma biomarkers showing the largest % increases included glycocholate (218%), heme (122%), 1,5‐anhydroglucitol (119%), 1‐palmitoleoyl‐glycerophosphocholine (95%), palmitoleate (64%), and creatine (53%). These changes are consistent with reduced insulin sensitivity in aging. In sum, energetic dysfunction appears central to pathological metabolic processes in aging skeletal muscle.
Whole‐body heat stress increases mitochondrial enzyme activity in mice skeletal muscle
Authors: Tamura Yuki , Matsunaga Yutaka , Masuda Hiroyuki , Takahashi Yumiko , Takahashi Yuki , Takashima Satoshi , Minagawa Hidehiro , Hoshino Daisuke , Hatta Hideo
Published: June 2021

PURPOSE

The purposes of present study were to investigate i) the chronic effects of whole‐body heat stress (WHS) on adaptation of mitochondrial enzyme activity and ii) the acute effects of WHS on kinase phosphorylation known to mediate mitochondrial biogenesis in mice skeletal muscle.

METHODS

ICR mice were divided into sedentary or WHS group. Mice in WHS group were exposed to hot environment chamber (30 × 20 × 13 cm, ambient temperature: 40 °C) for 30 min on each experiment day. In chronic experiment, we examined the effects of 3 weeks (Frequency: 5 days/week) WHS on maximal citrate synthase (CS) and 3‐Hydroxyacyl‐CoA dehydrogenase (3‐HAD) activities in plantaris muscle. In acute experiment, we studied the effects of a single WHS on phosphorylation of AMP activated protein kinase (AMPK), p38 mitrogen activated protein kinase (p38 MAPK) and calcium/calmodulin‐dependent protein kinase II (CaMK II) in plantaris muscle.

RESULTS

In chronic experiment, both maximal CS and 3‐HAD activities were increased in WHS group (CS: +35%, P<0.01, 3‐HAD: +49%, P<0.01). In acute experiment, phosphorylation of AMPK in WHS group was decreased (−43%, P<0.05). Phosphorylation of p38 MAPK was increased in WHS group (+252%, P<0.05). Phosphorylation of CaMK II was not different between groups.

CONCLUSION

Chronic whole‐body heat stress increased mitochondrial enzyme activities.
MnTBAP Reduces Adiposity and Increases Bio‐markers for Mitochondrial Biogenesis
Authors: Sosinsky Alexandra Z. , Brestoff Jonathan R. , Stansky Elena , Fussell Leila , Brodsky Timothy W. , Donohue Jacob , Sheppard Aaron , Reynolds Thomas H.
Published: June 2021

The purpose of this study was to determine if manganese tetrakis benzoic acid porphyrin (MnTBAP) treatment reduces adiposity and increases bio‐markers for mitochondrial biogenesis. Male C57B6 mice were fed a low fat diet (LFD) or a high fat (HFD) for five months. During the last 30 days of the dietary intervention, mice were given intraperitoneal injections of MnTBAP (10 mg/kg/day) or vehicle. MnTBAP treatment significantly decreased body weight (52.8±2 vs. 40.1±2.1) and epididymal white adipose tissue (EWAT) weight (2.53±0.11 vs. 1.47±0.13). PGC‐1α and nuclear respiratory factor‐1 (NRF1) were significantly higher in EWAT from mice treated with MnTBAP compared to mice treated with vehicle. Additionally, MnTBAP treatment increased the phosphorylation of AMPK on Thr 172, site whose phosphorylation is associated with increased AMPK activity. Because β‐adrenergic receptor activation can increase AMPK activity and PGC‐1α expression, we also examined the phosphorylation of hormone sensitive lipase (HSL) on Ser 563, the site phosphorylated by the cAMP dependent kinase (PKA). Phosphorylation of HSL was significantly increased in EWAT of mice treated with MnTBAP, indicating the activation of β‐adrenergic receptor signaling. Taken together, our data demonstrates that MnTBAP treatment reduces dietary‐induced obesity by a mechanism that may involve mitochondrial biogenesis.
A novel Mito‐Timer reporter gene for measurement of mitochondrial quantity and quality in vivo
Authors: Laker Rhianna Che , Xu Peng , Ryall Karen , Sujkowski Alyson , Zhang Mei , Adler Paul , Wessells Robert , Saucerman Jeff , Yan Zhen
Published: June 2021

Mitochondrial dysfunction plays an important role in many diseases, but there is no satisfactory method to assess mitochondrial quantity and quality in vivo. Here we engineered a novel pMito‐Timer reporter gene from the existing pTimer‐1 reporter gene. pMito‐Timer encodes a mitochondria‐targeted green fluorescent protein (GFP) when newly synthesized, which shifts irreversibly to red fluorescence (DsRed) when oxidized. Confocal microscopy confirmed that Mito‐Timer targets to mitochondria in cultured mouse myoblasts, Drosophila heart and indirect flight muscles, and adult mouse skeletal muscle. Ratiometric algorithm showed that conditions that cause mitochondrial stress lead to a significant fluorescence shift toward DsRed with a significant increase of DsRed puncta. Somatic gene transfer in adult skeletal muscle in mice showed that high‐fat diet induces the same changes, which could be completely ameliorated by exercise training. Exercise training also results in increases in mitochondrial volume that could be quantified. Therefore, pMito‐Timer can be used to report mitochondrial health under both normal and pathological conditions and will provide a valuable tool to multiple disciplines investigating the role of the mitochondria in disease.
Transplantation of Autologously‐Derived Mitochondria Protects the Heart from Ischemia‐Reperfusion Injury
Authors: Wakiyama Akihiro , Black Kendra M , Pacak Christina A , Ericsson Maria , Barnett Reanne J , Drumm Ciara , Seth Pankaj , Bloch Donald B , Levitsky Sidney , Cowan Douglas B , McCully James D
Published: June 2021

The ability of mitochondria to regulate myocardial homeostasis and energetic requirements is compromised following reduction or cessation of blood flow resulting in tissue necrosis and impaired cardiac function. We hypothesized that transplantation of autologously‐derived mitochondria immediately prior to reperfusion would ameliorate these effects. NZW rabbits were subjected to regional ischemia (RI) by temporarily snaring the left anterior descending artery for 30 min. Following 29 min. RI, mitochondria (RI‐Mito) or vehicle (RI‐V) were injected into the RI zone and the hearts recovered for 4 weeks. RI‐Mito decreased infarct size (7.9±2.9%) as compared to RI‐V (34.2±3.3%; P<0.05). Serial echocardiograms showed RI‐Mito hearts returned to normal contraction in early reperfusion but RI‐V hearts had persistent hypokinesia in the RI zone. The injected mitochondria were retained in the myocardium with the majority located in the interstitium but many were internalized by cardiomyocytes. The transplanted mitochondria enhanced oxygen consumption and upregulated proteomic pathways for enhanced myocardial energetics. Our results demonstrate that the transplantation of autologously‐derived mitochondria into the RI zone just prior to reperfusion provides cardioprotection both intracellularly and extracellularly to significantly decrease necrosis and enhance post‐ischemic functional recovery.
School foodservice managers’ positive support for school nutrition encourages healthy food environment
Authors: Meredith Catherine Angela , Kennedy Tay , Hildebrand Deana
Published: June 2021

Objective

Our objective is to understand school foodservice managers’ support for school nutrition programs and marketing strategies to promote an increase in fruit and vegetable consumption.

Methods

Data was collected using an online survey sent to all Oklahoma middle and junior high schools. The survey questions included the school and foodservice manager demographics, food‐service managers beliefs and perceptions of barriers to marketing strategies in school nutrition programs, what strategies schools were already using, successes in implementing nutrition marketing programs, and factors influencing decisions to change.

Results

98–100% of participants believed school nutrition was important to academic performance, and that it is the school foodservice's responsibility to provide healthy meals that appeal to students. The implementation of behavioral marketing strategies were seen in >;60% of schools, and even 33% of those using less popular strategies would continue their use. Financing impacted 86% of participants’ decisions to change, and delivery schedule of fruits and vegetables impacted 84% of decisions for change.

Conclusions

School foodservice managers are highly committed to supporting school nutrition and are willing to implement (if not doing so already) marketing strategies to help promote healthy food choices for students.
PTH‐stimulated urinary phosphate and cAMP excretion are absent in mice lacking adenylyl cyclase 6
Authors: Rieg Timo , Sharik Meaghen , Tang Tong , Aroonsakool Nakon , Murray Fiona
Published: June 2021

Parathyroid hormone (PTH) activates an unidentified isoform of adenylyl cyclase (AC) thereby retrieving Na+/Pi cotransporters from the proximal tubule membrane and increasing Pi excretion. To test for a role adenylyl cyclase 6 (AC6) we studied wild‐type (WT, n=8) and AC6 knockout (AC6−/−, n=6) mice in clearance experiments under anesthesia. Bolus application of vehicle (Veh; 0.85% NaCl, 0.5 μl/g bw) or PTH (1, 3, 10, 30 or 100 μg/kg bw) was followed by a 5 min distribution phase and a 15 min quantitative urine collection. After Veh application absolute (AE Pi) as well as fractional urinary Pi excretion (FE Pi) were significantly higher in AC6−/− vs WT mice (4.3±1.2 vs 0.8±0.3 nmol/min/g bw, and 23±6 vs 4±1 %, P<0.05 vs AC6−/−, respectively), and urinary cAMP excretion (AE cAMP) tended to be lower in AC6−/− vs WT mice (0.8±0.2 vs 1.5±0.4 nmol/min/g bw), while glomerular filtration rate was modestly lower in AC6−/− vs WT mice (8.9±1 vs 11.8±1 μl/min/g bw, P<0.05 vs AC6−/−). PTH dose‐dependently increased AE Pi, FE Pi and AE cAMP in WT mice (max responses of 678±205% vs Veh, 23±4%, and 624±136% vs Veh, P<0.05 vs Veh, respectively). In contrast to WT mice, PTH decreased AE Pi (max response −81±3%, P<0.05 vs Veh), did not change FE Pi excretion and AE cAMP (all doses not significant from Veh). Lack of PTH‐induced urinary Pi and cAMP excretion in AC6−/− mice is consistent with AC6 in the proximal tubule mediating these responses.
Hyperglycemia, low salt diet, and metabolic acidosis increase the expression of KCl cotransporters in the kidney
Authors: Melo Zesergio , Bautista Rocio , Cruz‐Rangel Silvia , Bobadilla Norma , Gamba Gerardo , Mercado Adriana
Published: June 2021

The KCl cotransporter isoforms KCC3 and KCC4 are expressed in several regions of the nephron, but their roles are largely unknown. To begin to understand the renal physiological aspects of KCCs, we evaluated the KCC3 and KCC4 mRNA and protein expression levels (real time RT‐PCR and Western blot, respectively), as well as their intrarenal distribution (confocal microscopy). The studied models in male wistar rats were hyperglycemia, 30 days after a single dose of streptozotocin (60 mg/kg), metabolic acidosis (NH4Cl 150 mM in drinking water during seven days), and low sodium diet (0.1% NaCl diet for seven days). KCC3 expression was significantly increased during hyperglycemia in renal cortex, at the basolateral membrane of proximal tubular cells. In contrast, KCC4 expression was not affected by hyperglycemia, but was significantly increased by low sodium diet, at the basolateral membrane of the thick ascending limb, and by metabolic acidosis in renal medulla, specifically at the basolateral membrane of alfa intercalated cells. These observations support a role for KCC3 in the response of proximal tubules to an increase in glucose concentration in the ultrafiltrate and points out to KCC4 as an exit pathway for potassium and chloride in the thick ascending limb of Henle during low sodium diet and as an important transporter in the response to metabolic acidosis by collecting duct cells.
Identifying metabolic pathways associated with leanness using domestic chickens as a model
Authors: Ji Bo , Lamont Susan , Middleton Jesse , May Amanda , Campagna Shawn , Voy Brynn
Published: June 2021

Domestic broiler chickens rapidly accumulate adipose tissue and are naturally hyperglycemic and insulin resistant, making them an attractive model for the study of obesity and insulin resistance. We previously showed that 5‐hour fasting rapidly upregulated pathways that would limit fat storage and promote fatty acid oxidation in broiler white adipose tissue. Our current objective was to determine if genetically determined leanness in chickens was due to activation of the same pathways induced by fasting. We used Affymetrix microarrays to identify differentially expressed genes in white adipose tissue of Fayoumi and broilers, which differ in adiposity by approximately 3‐fold. Cluster analysis revealed distinct similarities between expression profiles of lean Fayoumi and fasted broilers, compared to fed broilers, including genes involved in substrate oxidation. Lean chickens showed significant upregulation of energy‐sensing signaling pathways in white adipose tissue based on mRNA and Western blot analyses, including upregulation of the 5’ AMP‐activated protein kinase (AMPK) pathway. Adipose metabolites and fatty acid profiles were measured using LC‐MS/MS and GC‐MS, respectively. Our results indicated significant differences in adipose metabolism, stress signaling and adipogenesis between genetically lean and fatty lines of chickens, which may have relevance for studies of human obesity.
The effect of tracheal occlusion on the load compensation response and the changes in inhibitory neurotransmitter in the brainstem of conscious rats
Authors: Tsai Hsiu‐Wen , Condrey Jillian , Adams Sherry , Davenport Paul W
Published: June 2021

Respiratory load compensation in conscious animals is mediated by cortical, subcortical modulation and brainstem mediated reflexes. We hypothesized that consciousness behavior would reconfigure the brainstem mediated respiratory load compensation reflex in respond to tracheal occlusion (TO). We also hypothesized that glycinergic neurons in the NTS would not be activated in conscious rats as we found in anesthetized rats in a previous study. A tracheal occluder and diaphragm electrodes were implanted in six experimental (E) and six sham (S) rats for the measurement of respiratory parameters. Seven days after recovery, the E rats had 2–3 seconds TOs separated by 10–15 unloaded breaths for 10 minutes. Ninety minutes after TO, the rats were anesthetized, brainstem were perfused and harvested for the double immnofluorescence staining of c‐Fos and glycine transporter 2. The results showed that conscious rats prolonged expiratory time (Te) in respond to TO but inspiratory time (Te) was unaffected by the load. The glycinergic neurons in the NTS were activated in conscious rats. In conclusion, conscious rat load compensation responses are characterized by maintaining normal Ti and modulating Te which differs from anesthetized rats, but glycinergic neurons in the NTS were activated which are similar to anesthetized rats.
LPS increase of ciliary beat frequency in respiratory ciliated cells.
Authors: Carreno Daniela Veronica , Llados Carmen , Rios Mariana , Cohen Noam , Villalon Manuel
Published: June 2021

Mucociliary clearence constitutes a barrier against contaminants and microorganisms inhaled from the environment. Its efficiency depends mainly on the frequency of ciliary beat (CBF). Airways contaminants like lyposaccharide (LPS) activate a specific toll like receptors (TLR4) of the immune system that produce an inflammatory response associated to the production of cytokines by the airway epithelium. However, the effect of LPS in the effectiveness of mucociliary clearance it is unknown so we studied the effect of LPS in frequency of CBF and the mechanism involved.

Primary cultures of mouse (Balbc) tracheal epithelium were incubated with different concentrations of LPS and P2×7 and pannexin‐1 inhibitors,(oATP, KN‐62, Probenecid and Carbenoxolone), CBF was determined using a microphotodensitometric technique (n >; 3). ATP was measured in culture medium using luciferin‐luceferase reagent and. All these experiments were statistically analyzed with ANOVA, and post‐test Tukey.

LPS induce an increase in CBF in a dose response manner that was blocked by the incubation of all inhibitors used. LPS produce a raise in ATP concentration in culture media after 20min of incubation with 10 μg/ml.

These results indicate that LPS affect ciliary activity in the airways by releasing ATP to the extracellular where P2×7 and pannexin‐1 could be involved.
A simple dynamical model of the oxygen uptake in the human pulmonary acinus
Authors: KANG Min‐Yeong , FOUCQUIER Aurelie , FILOCHE Marcel , SAPOVAL Bernard
Published: June 2021

We have developed a mathematical model called a “machine acinus.” The machine acinus has the size and configuration of a real acinus and operates under realistic dynamics. All the complexity of O2 trapping and blood saturation are merged into a parameter called the integrative permeability, Ω, whose value is linked to the alveolar pressure, PA,O2, and the O2 uptake, VO2 (Foucquier et al., Respir Physiol Neurobiol, 2013).

Dynamic convection‐diffusion equations for the machine acinus are solved numerically for rest and peak exercise. Besides the adaptation at rest to the cardiac output, the results demonstrate the necessity of a hypoxic vasoconstriction adaptation to diffusion limitations. We show that a healthy adult's breathing can be predicted, at rest and exercise, with only two parameters: the threshold pressure for vasoconstriction (close to 100 mmHg) and Ω. If we model emphysema and pulmonary edema as a loss of acinar surface and a decrease in the permeability, respectively, we find that a safety margin against these diseases exists at rest. For instance, VO2 preserves 90% of its normal value under 50% surface reduction. In addition, our model predicts that the acinar region where the diseases take place is important. When the surface loss is concentrated in a distal region, VO2 is significantly reduced compared to that with the loss in the proximal region.

This work was supported by Air Liquide Santé International.
Navigation within the cellular monolayer
Authors: Kim Jae Hun , Serra‐Picamal Xavier , Tambe Dhananjay T , Park Chan Young , Sadati Monirosadat , Butler James P , Trepat Xavier , Fredberg Jeffrey J
Published: June 2021

Confronted by a cell‐free gap, a cellular monolayer ordinarily extends its free edge until the gap is filled. Although this process is arguably the simplest of all dynamical patterning modules, governing physical principles that might explain this process remain obscure. To expose physical forces that cause constituent cells to move as they do, we placed in the path of an advancing epithelial cell sheet an island upon which cells could not adhere. The monolayer impacts but cannot cover this island, and is therefore said to become frustrated. Systematic components of the resulting nonuniform velocity field and underlying force fields reveal striking dynamical features. Far from the frustrated edge, local traction forces pull systematically along the local migration velocity vector. Near the frustrated edge, however, local traction forces veer away from the local velocity vector by angles approaching 90°. At the frustrated edge itself, traction forces pull systematically normal to that edge, but generate no normal displacements. Corresponding intercellular stresses reveal unanticipated but fundamental dynamical patterning modules that call for a new physical picture of monolayer dynamics.

This work was supported by the Spanish Ministry for Science and Innovation (BFU2009–07595), the European Research Council (Grant Agreement 242993) and the National Institutes of Health (R01HL102373, R01HL107561).
Bio‐Mechanical Properties of the Mammalian Urothelium
Authors: Zeidel Mark L , Zhou Enhua , Yu Weiqun , Fredberg Jeffrey , Mathai John C
Published: June 2021

In the bladder urothelium, the urothelial surface umbrella cells (UC's) maintain an exceptionally tight barrier between urine and blood that prevents noxious leakage. The permeability barrier has been shown to reside on the apical surface of the umbrella cells, which are covered by specialized proteins called uroplakins. Because these proteins form plaques on the surface of umbrella cell and cover up to 90% of the urothelial surface, the urothelial surface is considered to be rigid. It is not clear how a rigid surface can be flexible as the bladder undergoes stretch and relaxation cycles. To develop an understand of the mechanical properties of the urothelial surface we attached magnetic beads coated with polylysine to the apical membrane (AM) surface of intact UC's in intact urothelia and measured their elastic moduli G, by optical magnetic tracking cytometry, OMCT. Control UC's exhibited G values which tracked closely with highly deformable red blood cells (which must deform readily to traverse capillaries). Removal of surface UC's with protamine exposed underlying intermediate cells, which exhibited G values 12–15 fold higher than UC's, and similar to cultured MDCK cells. Fixation of UC's with formaldehyde raised G by two orders of magnitude. Because submembrane actin often plays a critical role in reducing deformability, we performed confocal microscopy on control UC's and found very little subapical actin. In UC's basolateral actin was abundant, and actin was abundant under apical and basolateral membranes of intermediate cells. We conclude that UC's are strikingly deformable, despite the dense array of uroplakins in their apical membranes. Whether this deformability results from the physical effect of uroplakins or the relative lack of subapical actin will be determined using uroplakin knockout mice.
Direct fed microbial supplementation affects host immune function and energy expenditure
Authors: Ballou Anne , Qiu Rongsheng , Ali Rizwana A , Croom W Jim , Koci Matthew D
Published: June 2021

Direct fed microbials (DFM) have been the focus of considerable scientific and public interest as we learn how the gut microbiome impacts host health. Previous studies in our laboratory using a rapidly growing chicken model demonstrated an increase in thymus tissue respiration and a decrease in intestinal respiration following DFM supplementation, but no differences in whole‐body respiration or growth. Further research has demonstrated increased utilization of ATP in peripheral blood mononuclear cells isolated from DFM‐fed animals, accompanied by a faster antigen specific antibody response. DFM‐fed animals immunized against sheep red blood cells (SRBCs) produced anti‐SRBC IgG within 7 days of immunization, while SRBC specific IgG was not detected in control‐fed animals until 14 days post immunization. This suggests DFM supplementation induces changes that enhance humoral immunity. Analysis of host intestinal gene expression revealed changes in the ileum consistent with decreased inflammation and increased antibody production (↑IL‐10, ↓IL‐12RB2). Interestingly, changes in gene expression in the cecum were consistent with increased inflammation (↑IL‐2 and IL‐12RB2). Understanding how DFM interact with the host and the cytokines produced will be critical in developing therapies that promote health through manipulation of the host flora. Research funding provided by StarLabs, Clarksdale, MO.