bluuebunny/crossref_metadata_2025_split huggingface dataset:
Does Protein Sulfuration Take Place in the Heart?
Authors: Sonobe Takashi , Haouzi Philippe 
Published: November 2023

Endogenous hydrogen sulfide (H2S) has been suggested to play a physiological role through protein sulfuration (also referred as sulfhydration) in the regulation of cardiac contractility. The sulfuration is a process by which H2S combines to free cysteine residue on proteins to create persulfide (protein‐S‐SH), changing protein conformation, such as in calcium channels, and functions. Since any new molecule of free H2S produced will immediately combine with the iron present on myoglobin or will be oxidized, our objective was to determine whether increasing endogenous H2S production can actually increase the pool of H2S combined with cysteine residues in the heart.To achieve this goal, we infused exogenous H2S up to a level that will alter cardiac contractility in order to create conditions wherein soluble H2S concentrations increase to levels higher than those reached by endogenous sulfide in the heart. The presence of sulfurated protein in the heart was identified by measuring gaseous H2S released after reducing disulfide bonds. TCEP was chosen as a potent reducing agent instead of dithiothreitol (DTT), previously used for this purpose in the literature, as DTT possesses two thiol groups (−SH) a significant source of H2S. Hearts were removed from control animals and animals exposed to 0.8 mg/min NaHS until cardiac depression‐induced hypotension was produced. The hearts were immediately homogenized in glycine‐NaOH buffer (pH 9), to prevent any evaporation of gaseous H2S. The homogenate was transferred into the 50‐ml chamber filled with sodium phosphate buffer (final pH ~6). At this pH, HS− will easily convert into gaseous H2S, in keeping with H2S partial pressure, and measured in the chamber headspace. The headspace was continuously flowed with N2, and H2S was directly measured by a voltammetry H2S analyzer before and after TCEP (5 mM).We found that the level of H2S produced by TCEP was similar and very low (below 0.5 nmol/g of protein) in both the control and intoxicated hearts, despite levels of free H2S in the blood above 10 microM in the latter. In contrast, the pool of H2S in albumin solution (10% in saline) incubated with H2S for 10 min, increased as a function of H2S concentrations using 0, 2, and 20 microM NaHS and reaching 10.6 ± 1.1, 11.8 ± 0.7 and 13.3 ± 0.4 nmol/g respectively. The change in H2S remained however extremely modest.Toxic levels of soluble H2S were unable to increase the pool of H2S liberated from the heart in a strong reducing environment. This suggests that free H2S in the heart is immediately trapped by other compounds such metallo‐proteins, e.g. myoglobin, present in the heart or is oxidized in the mitochondria before reacting with proteins, in contrast to a solution of albumin unable to produce these effects. Even in the latter, the pool of H2S produced by an increase in free H2S appears to be extremely small and to require toxic levels of sulfide to be affected.
Effects of excess succinate on cardiomyocyte mitochondrial H2O2 production and cell death
Authors: Williams Anna Marie , Olson Jessica , Yan Yasheng , Bai Xiaowen , Camara Amadou K.S. , Bosnjak Zeljko J. 
Published: November 2023

IntroductionDuring myocardial infarction injury, reactive oxygen species (ROS) generation in the first few minutes of reperfusion has been shown to cause significant cellular dysfunction and death of the myocardium. Recent studies suggest ROS generation during reperfusion is due to accumulation of intermediate citric acid cycle metabolites, specifically succinate accumulation. Additionally, previous studies suggest that an increase in fumarate accompanied by an increase in succinate is cardioprotective. In this study, we examined the effect of excess succinate on H2O2 production and cell death. We hypothesized that excess succinate increases H2O2 production through reverse electron transport in mitochondria isolated from Sprague‐Dawley rat hearts and increases cell death in induced pluripotent stem cell‐derived cardiomyocytes (iPSC‐CMs) and that addition of fumarate would abolish this phenotype.MethodsThe left ventricles of Sprague Dawley male rats were collected and minced. Mitochondria were isolated using differential centrifugation. Mitochondria were exposed to 5 mM succinate with or without 1μM rotenone (a complex I inhibitor). H2O2 production was measured using an Amplex Red assay. Human iPSCs were cultured to confluency and differentiated into CMs. Contracting cells were immunostained for cardiac specific markers to confirm >90% purity of CMs. CMs were exposed to 5 mM dimethyl succinate with or without 5 mM dimethyl fumarate for 1 hour followed by 24 hours of reperfusion in basal media. Cell viability was measured using propidium iodide staining.ResultsExcess succinate caused a significant increase in H2O2 production in mitochondria isolated from Sprague Dawley rat hearts. This effect was abolished with addition of rotenone, showing that H2O2 production was occurring through reverse electron transport. Dimethyl succinate also caused significant cell death in iPSC‐derived CMs. Dimethyl fumarate with dimethyl succinate did not abolish increased cell death.ConclusionsWe have confirmed that excess succinate causes a significant increase in H2O2 production through reverse electron transport in mitochondria isolated from Sprague Dawley rat hearts and a significant increase in cell death in iPSC‐derived CMs. Fumarate in addition to excess succinate did not have a cardioprotective effect in iPSC‐CMs. However, this may be a toxic effect rather than a metabolic effect. Further experiments detailing the mechanism by which this occurs may reveal new therapeutic targets to reduce the detriment of ROS production from ischemia/reperfusion injury.Support or Funding InformationNIH/NIGMS Program Project Grant 2P01GM066730‐11Program Director: Zeljko J. Bosnjak “Mechanisms of Anesthetic Cardioprotection”Project II: “MicroRNA in Anesthetic Cardioprotection”
Activation of the Calcium Sensing Receptor potentially inhibits Kv1.5 channel activity
Authors: Ayon Ramon J , Tang Haiyang , Yee Allison M , Dash Swetaleena , Ek‐Vitorin Jose F , Makino Ayako , Yuan Jason X.‐J. 
Published: November 2023

The Calcium sensing receptor (CaSR) is class of G protein coupled receptors (GPCR) that can be activated by extracellular Ca2+ and Mg2+. Activation of CaSR can stimulate the phospholipase C (PLC) signaling pathway that leads to synthesis of inositol 1,4,5 triphosphate (IP3) and diacylglycerol (DAG). Voltage‐gated potassium (Kv) channels activity is essential for establishing resting membrane potential in a variety of cell types including pulmonary artery smooth muscle cells (PASMC). Indeed, stimulation or inhibition of K+ channels can easily determine cell fate, as K+ channel activity is associated with cell proliferation, survival and apoptosis. It has been reported that some K+ channel classes are regulated by GPCRs. For example, Kv1.2, and members of the two‐pore domain K+ channel family (TASK‐1 and TASK‐3) were shown to be inhibited by GPCR activation. Interestingly, Kv1.5 channel activity can also be suppressed by stimulation of GPCR via the Src tyrosine kinase pathway. However there are no reports to date that have shown any functional interaction between CaSR and Kv1.5. In this present study, we examined the effects of CaSR activation on Kv1.5 channel activity by transfection of KCNA5, which encodes for the Kv1.5 pore‐forming α subunit, alone or cotransfection of KCNA5/CaSR in HEK293 cells. Overexpression of KCNA5 and CaSR/KCNA5 in HEK293 cells were confirmed by Western blot and Immunofluorescence. Kv1.5 current amplitude (IKv1.5) was significantly attenuated by 1.8 mM external Ca2+ in cells transfected with both CaSR/KCNA5 but not in cells transfected with KCNA5 alone. To determine whether this Ca2+ induced decrease of IKv1.5 was due to activation of PLC‐DAG‐IP3 signaling cascade we used the PLC inhibitor U‐73122. Preliminary data showed that 10uM U‐73122 was capable of antagonizing the external Ca2+ induced decrease in IKv1.5. This would suggests that activation of CaSR by way of external Ca2+ is capable of inhibiting Kv1.5 channel activity via PLC signaling pathwaySupport or Funding InformationResearch supported by NIH Grants (HL115014, HL066012 and HL098053).
Characterization of Respiratory Activity in Spontaneously Breathing Urethane‐Anesthetized 6‐OHDA SN‐lesioned Parkinson's Disease Rat Model
Authors: Solomon Irene C , Collins William F 
Published: November 2023

Respiratory dysfunction in Parkinson's Disease (PD) patients manifests as a variety of altered breathing patterns that are suggested to result from impairment of central respiratory control. To date, only a limited number of studies have used a rat PD model to begin to explore respiratory aspects of PD. Therefore, to better characterize the respiratory phenotype of PD, we have begun a series of experiments in the 6‐hydroxydopamine (6‐OHDA) neurotoxin‐induced unilateral SN lesion rat model. For these experiments, spontaneously breathing urethane‐anesthetized rats are being exposed to room air (basal conditions) and either hypoxic (12% O2) or hypercapnic (7% CO2) gas, and inspiratory‐related (tongue and/or diaphragm), and in some cases expiratory‐related (external oblique), EMG activity are recorded. Our preliminary data indicate that compared to control rats, SN‐lesioned rats (at 1‐week or 1‐month post‐lesion) exhibited (1) significantly higher basal breathing frequencies; (2) a similar increase in frequency, but a variable increase in the magnitude of the amplitude response to hypoxia; and (3) a slightly enhanced increase in breathing frequency and amplitude in response hypercapnia. These preliminary observations suggest that (1) the 6‐OHDA‐lesioned rat/rodent is a viable model for studying respiratory abnormalities in PD and (2) PD may differentially affect hypoxic and hypercapnic ventilatory responses.Support or Funding InformationThomas Hartman Center for Parkinson's Research at Stony Brook University
Tauopathy Induced Progressive Cell Loss of FoxP2‐Expressing Neurons in the Kölliker‐Fuse nuclei (KFn) is Tightly Linked to Clinically Relevant Laryngeal Dysfunction in Tau‐P301L Mice
Authors: Dutschmann Mathias , Bautista Tara , Bondarenko Evgeny , Nalivaiko Eugene , Stanic Davor 
Published: November 2023

The developmental transcription factor FoxP2 is a highly reliable marker for the pontine KFn. The KFn have important function in the control of laryngeal adductor function during breathing and during a variety of upper airway motor behavior (e.g swallowing, vocalization).Immunohistochemistry for FoxP2 and hyperphosphorylated Tau protein in an established mouse model of tauopathy (Tau P‐301L) indicates: (i) early onset tauopathy (age 3–5 months) occurs in the KFn region of otherwise non‐symptomatic Tau‐P301L mice; (ii) early KFn tauopathy can be identified before the onset of severe cognitive and/or motor dysfunction by an impaired sniff pattern in plethysmographic recordings in awake animals after exposure to trigeminal and non‐trigeminal odors (n=18); (iii) with aging, a progressive cell loss of FoxP2‐expressing neurons of the KFn can be detected. At terminal stages of 8–9 months old Tau‐P301L, a high percentage of the FoxP2‐expressing cells disappeared. The progressive cell loss in KFn correlates with emerging laryngeal dysfunctions which are in particular expressed as a dysphagia phenotype. As reported previously also the breathing pattern indicates progressively shows paradoxical inspiratory laryngeal adduction (Dutschmann et al., 2010). WE conclude that tauopathy linked neurodegeneration of KFn neurons may significantly contribute to upper airway disorders such as dysphagia mutism and paradoxical vocal cord motion seen in a variety of neurodegenerative diseases such as Alzheimer's disease Parkinsonism, frontotemporal dementia and motor neuron disease.Support or Funding InformationThe work was supported by ARC future fellowship and the Florey Institute for Neuroscience and Mental Health
Dietary Fiber and Exercise: Effects on Muscle Function, Cognition, and Short‐Chain Fatty Acids in Mice
Authors: Pence Brandt D. , Bhattacharya Tushar K. , Rytych Jennifer L. , Park Pul , Allen Jacob M. , Sun Yi , McCusker Robert H. , Kelley Keith W. , Johnson Rodney W. , Rhodes Justin S. , Woods Jeffrey A. 
Published: November 2023

Short chain fatty acids (SCFAs) contribute to immune and brain function and are produced by gut bacteria through metabolism of fermentable fiber. We examined the relationship between dietary fiber and changes in cognition, muscle function, and cecal SCFA content with or without voluntary exercise in mice. Six‐week old male C57Bl/6J mice were fed AIN‐93M diet (Ctrl) or AIN‐93M with 5% pectin (Pect) substituted for cellulose for 6 weeks and voluntarily exercised on a wheel (VWR) or remained sedentary (SED), constituting 4 groups of N=5/group (Ctrl‐Sed, Ctrl‐VWR, Pect‐Sed, Pect‐VWR). Mice underwent a battery muscle and cognitive function testing after 4 weeks of feeding, and at sacrifice, we collected cecal contents for quantitation of SCFAs. VWR did not affect body weight over the course of the intervention, while Sed mice gained 2 grams (p<0.001, time*VWR). Neither VWR or dietary fiber type affected performance on the active avoidance task or Morris Water Maze task. Interestingly, both dietary fiber and VWR decreased grip strength, although only the pectin effect remained after normalization to body weight (p=0.004). VWR unsurprisingly increased performance on the rotarod (p=0.028) and exhaustive fatigue test (p=0.012). Pectin increased cecal concentrations of SCFAs acetate (p=0.001), propionate (p=0.002), and butyrate (p=0.005). Interestingly, VWR significantly increased acetate (p=0.030), and there was a significant VWR effect (p=0.002) and VWR*fiber interaction (p=0.031) such that the pectin + VWR group had the highest concentration of cecal propionate. In conclusion, pectin and/or VWR did not affect cognitive function but increased cecal SCFAs in young mice. These results may have implications for nervous system and immune functions.Support or Funding InformationFunded by the Abbott‐UIUC Center for Nutrition, Learning, and Memory
Moderate Intensity Dynamic Resistance Training Induced Cardiovascular Benefits in Female Hypertensive Rats
Authors: Araujo Amanda , Bernardes Nathalia , Dias Danielle , Mello Tafne , Costa Gabrielly , Brito Janaina , Irigoyen Mária Cláudia , De Angelis Kátia 
Published: November 2023

The dynamic resistance training (DRT) has been the subject of recent studies, however studies using post menopausal women or hypertensive women controlled by pharmacological treatment focusing just on metabolic parameters. Few studies evaluated the chronic effects of this type of training in blood pressure (BP) with direct measurement in untreated hypertensive females. The objective of this study was to evaluate the effects of DRT on BP, physical capacity and muscle weight in spontaneously hypertensive rats. Thus, we used 14 adult females SHR, divided into two groups (n = 7): sedentary females (FS) and trained females (FT). Maximal exercise testing was conducted before and after the training period. The DRT in moderate intensity (40–60% of the maximal load) was performed in a ladder adapted for rats per 8 weeks. After this period, there were blood glucose and triglyceride measurements and we performed cannulation of the carotid artery for direct measurement of BP. Heart tissue and soleus, plantaris and gastrocnemius muscles were weighted. There was improvement in physical capacity in the FT group (Maximum exercise test pre 192.75 ± 12.19 vs. post 471.13 ± 27.23). There were no difference in heart rate (FT: 386.04 ± 11.85 vs. FS: 371.93 ± 12.19 bpm) and metabolic evaluations (blood glucose 103.00 ± 1.94 vs. 102.25 ± 2.78 mg/dl; triglycerides: 112.00 ± 3.71 vs 122.25 ± 8.37 mg/dl, FT vs. FS respectively). Moreover, there were no differences in the weight of the gastrocnemius muscle (p = 0.928) and right ventricle (p = 0.549) between studied groups. DTR induced reduction in mean, systolic and diastolic BP (mean: 164.78 ± 4.96 vs. 179.20 ± 2.61; systolic: 188.97 ± 5.02 vs. 203.33 ± 4.11; diastolic: 142.67 ± 6.80 vs. 156.83 ± 2.29 mmHg, FT vs. FS respectively). Additionally, FT rats presented increased soleus and plantaris muscles and left ventricle weights as compared to FS rats (p <0.05). We conclude that the moderate intensity DRT induced BP reduction associated with cardiac hypertrophy, suggesting a positive role of this approach to hypertension management in females.Support or Funding InformationFAPESP 2015/10329‐5, CNPq 457200/2014‐6, CAPES 88881.062178/2014‐1
Effect of Aging on the Inspiratory Muscle Metaboreflex
Authors: Smith Joshua R , Broxterman Ryan M , Hammer Shane M , Alexander Andrew M , Didier Kaylin D , Barstow Thomas J , Kurti Stephanie P , Harms Craig A 
Published: November 2023

Activation of the inspiratory muscle metaboreflex leads to increased sympathetic outflow, mean arterial pressure (MAP), limb vascular resistance (LVR), and decreased limb blood flow. With aging, the skeletal muscle metaboreflex has been reported to be attenuated, similar, or exaggerated compared to younger adults. However, it is not known if aging influences the inspiratory muscle metaboreflex.PurposeThe purpose was to determine if aging influences the inspiratory muscle metaboreflex in healthy humans. We hypothesized that compared to younger adults, older adults would exhibit less of: 1) an increase in MAP and diastolic blood pressure (DBP), 2) a decrease in limb blood flow, and 3) an increase in LVR.MethodsSixteen healthy older (M:2/W:6; 65.3 ± 5.5 yrs) and young (M:2/W:6; 22.3 ± 2.9 yrs) adults were recruited for this study and visited the laboratory on three different occasions. All young women were tested during the early follicular phase of their menstrual cycle and all older women were post‐menopausal. On the first visit, subjects were familiarized with all procedures and measurements. The next two visits were randomized and subjects performed an inspiratory resistive breathing task (IRBT) at ~2% or ~70% of their maximal inspiratory mouth pressure (PImax) for 20 min. During the IRBTs, the breathing frequency was 20 breaths per min with a 0.5 duty cycle. At rest and during the IRBTs, blood pressure was measured via automated oscillometry, femoral artery blood flow (FABF) was measured via Doppler ultrasound, end tidal CO2 was continuously monitored, and LVR was calculated MAP divided by FABF. Surface EMGs were placed on the leg to ensure no muscle contraction occurred.ResultsDuring the 20 min at ~70%PImax, older adults had a greater (p<0.05) increase in MAP (O: 12.1 ± 4.1% vs. Y: 2.3 ± 4.1%), SBP (O: 16.1 ± 12.6% vs. Y: 5.7 ± 4.9%), and DBP (p=0.06) (O: 9.0 ± 10.6% vs. Y: 0.6 ± 5.2%) compared to young adults. No differences (p>0.05) were present in HR or FABF (O: −13.6 ± 12.0% vs. Y: −7.3 ± 7.3%) over the 20 min. However, older adults had a greater increase in LVR compared to young adults (O: 33.5 ± 19.9% vs. Y: 13.9 ± 12.3%).ConclusionThese data suggest that aging leads to an exaggerated inspiratory muscle metaboreflex in healthy humans.
Whole‐Body Heat Loss is Enhanced in Older Adults Following a Summer in a Humid Continental Climate
Authors: Poirier Martin P. , Dervis Sheila , Flouris Andreas D. , Kenny Glen P. 
Published: November 2023

It has recently been shown that older adults have a reduced capacity to dissipate heat during exposure to extreme heat compared to their younger counterparts, resulting in a 1.7‐fold greater increase in body heat storage. However, it currently remains unclear whether older adults demonstrate any seasonal adaptations in their ability to dissipate over the course of a typical hot humid summer (e.g. Central Canada). Therefore, the purpose of this study was to examine the effects of aging on whole‐body heat loss and heat storage during an extreme heat exposure prior to (before June) and at the end of the summer (September). Five young (Young, age: 25 ± 3 years; body fat: 19 ± 6%) and five older (Older, age: 64 ± 7 years; body fat: 26 ± 9%) adults matched for body weight (Young: 82 ± 18 kg; Older: 86 ± 12 kg) and body surface area (Young: 1.9 ± 0.2 m2; Older: 2.0 ± 0.2 m2) rested for 3 hours in the heat (44°C, 30% RH). Whole‐body heat loss and metabolic heat production were measured continuously by direct and indirect calorimetry, respectively. Body heat storage was calculated as the temporal summation of heat production and heat loss. Our results show that the older adults had a reduced rate of whole‐body heat loss at the 1‐hour (Young: 105 ± 20 W vs. Older: 76 ± 12 W, p=0.021) and 2‐hour (Young: 115 ± 28 W vs. Older: 83 ± 11 W, p=0.048) time points prior to the start of summer relative to their younger counterparts. No differences were measured between age groups at the end of the 3‐hour heat exposure (p>0.05). As a result of the lower rate of heat loss, the older adults stored 1.3‐fold more heat than the young adults (170 ± 72 kJ, p=0.01). Following the summer period, no differences in the rate of whole‐body heat loss were measured between groups throughout the 3‐hour heat exposure. As a consequence, the change in body heat storage was similar between age groups (Young: 196 ± 113 kJ vs. Older: 226 ± 102 kJ, p=0.67), demonstrating that older adults were able to reduce the amount of heat stored within their body by 43% after 3 months of summer heat exposure in a humid continental climate. These results show that seasonal adaptations can improve whole‐body heat dissipation in older adults, thereby mitigating the age‐related impairments in the body's physiological capacity to dissipate heat during an extreme heat exposure.Support or Funding InformationFunding support: This study was funded by the Canadian Institutes of Health Research (286363, grant held by Dr. Glen P. Kenny).
Ablation of phosphatidylethanolamine methyltransferase promotes white adipose browning in mice
Authors: Strong Stephanie , Verkerke Anthony , Johnson Jordan , Wentzler Edward , Funai Katsuhiko 
Published: November 2023

Obesity is caused by energy intake that chronically exceeds energy expenditure. Emerging evidence suggests that white adipose tissues can be reprogrammed to express mitochondrial uncoupling protein 1 (UCP1) to promote thermogenesis. This transformation, referred as “browning” of white adipose tissue, can increase energy expenditure and prevent obesity. Mice with a whole body knockout of phosphatidylethanolamine methyltransferase (PEMT) are protected from diet‐induced obesity due to an increase in whole‐body energy expenditure. However, the mechanism that promotes energy expenditure in these mice is unknown. We hypothesized that the absence of PEMT results in the browning of white adipose tissues. In this study, we examined adipose tissues from wild type (WT) and whole‐body PEMT knockout (PEMTKO) mice fed with a 10 week high‐fat diet. Inguinal and epididymal white adipose tissue (iWAT and eWAT) were analyzed for UCP1 expression by quantitative‐PCR, western blotting and immunohistochemistry. We found that mice lacking PEMT exhibited elevated RNA and protein abundance of UCP1 in iWAT and to a lesser extent in eWAT. These findings support our hypothesis that browning of white adipose tissue may contribute to increased energy expenditure in mice lacking PEMT. In future experiments, we will determine whether the absence of PEMT specifically in adipose tissues will promote browning and increased energy expenditure.Support or Funding InformationThis work was supported by NIH grant DK095774 to KF and APS/NHLBI STRIDE fellowship 1 R25 HL115473‐01 to SS.