bluuebunny/crossref_metadata_2025 huggingface dataset:
Interaction between Calmodulin and Lysosomal Vesicle‐Associated Membrane Protein 8
Authors: Yao Annie , Bloomfield Christina , Tran Quang‐Kim
Published: June 2021

Fusion of intracellular membranes is an important step in key processes such as exocytosis. This process is directly controlled by multiple vesicle‐associated membrane proteins (VAMPs). However, its regulatory inputs remain incompletely understood. Calmodulin is the key transducer of intracellular calcium signals that has been shown to control neurotransmitter release via its interaction with VAMP2. VAMP8 is a distinct protein located on the lysosomal membrane and is important for fusions of intracellular membranes. We hypothesized that calmodulin directly interacts with VAMP8, thereby controlling lysosomal fusion. In this study, we identified the calmodulin‐binding domain on VAMP8 and characterized the biochemical properties of the interaction.

Using a new biosensor method to screen for calmodulin‐binding sites, we identified a 20‐a.a. domain on VAMP8 as its calmodulin‐binding domain; truncation of three C‐terminal residues on this sequence significantly reduced binding affinity. To determine the concentrations of calcium at which this interaction can occur, we simultaneously monitored the responses of VAMP8 biosensors and a spectrally suitable calcium indicator in the presence of saturating calmodulin concentration and incremental addition of calcium. Control experiments demonstrated absolute absence of bleed‐over in this system. These determinations revealed that calmodulin interaction with VAMP8 is calcium‐dependent and can occur across the physiological range of cytoplasmic calcium concentration.

These data indicate novel roles for calcium and calmodulin in regulating VAMP8 function. The results also suggest potential roles in autophagy for factors that control calcium signals, calmodulin expression and its dynamic target interactions.

Support or Funding Information

National Institutes of Health Grant HL112184 and Des Moines University Grant IOER‐090717

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Effect of bile acids feeding on atherosclerosis in ApoE−/− mice
Authors: Escher Geneviève , Zurkinden Line , Vogt Bruno
Published: June 2021

Bile acids (BAs) account for lipids absorption in the small intestine and are key regulators of cholesterol homeostasis as they clear cholesterol excess in the liver. Therefore, we hypothesize that long term BAs feeding could prevent the development of atherosclerosis.

To prove this, we took ApoE−/− mice and fed them for 8 weeks with a western diet (WD) or a WD containing 0.1% cholic acid (CA) (WD‐CA) or 0.1% chenodeoxycholic acid (CDCA) (WD‐CDCA) and assessed their plasma lipoprotein and hepatic lipid content, intestinal cholesterol absorption and atherosclerosis.

WD‐CA increased plasma LDL‐C by ~75%, HDL‐C by ~30%, hepatic cholesterol by ~40% and cholesterol ester by ~300%. WD‐CA additionally increased cholesterol absorption by 25%. All these changes led to a 100% increase of the atherosclerotic lesions. In contrary, WD‐CDCA had no effect on plasma lipoproteins and hepatic cholesterol but massively increased hepatic cholesterol ester. WD‐CDCA additionally decreased cholesterol absorption by 25%, but atherosclerotic lesions were of the same magnitude as in ApoE−/− mice fed with WD.

Long term administration of CA and CDCA enhanced cholesterol accumulation in the liver and had no benefit towards atherosclerosis development in ApoE−/− mice. Even more, CA was atherogenic, mainly because of increased plasma lipids and intestinal cholesterol absorption. Despite improved intestinal cholesterol elimination, CDCA treatment did not reduce atherosclerosis. Other strategies are required to reduce atherosclerosis without causing liver damage in mice.

Support or Funding Information

None

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Hemodynamic Responses to Ventricular Pacing in the Fish Heart Depend on Repolarization Duration at the Paced Regions
Authors: Azarov Jan E , Vityazev Vladimir , Vaykshnorayte Marina
Published: June 2021

Introduction

Spatiotemporal distribution of myocardial action potential durations is heterogeneous but a role of these heterogeneities is largely unknown. Heart ventricular contraction needs muscle mechanical heterogeneity, namely activation spread from “slow” to “fast” muscle elements, which are expected to have longer and shorter action potentials, respectively. We hypothesized that the longer repolarization duration at the primary activation area provides the better pump function. The objective of the present study was to evaluate an association between the repolarization duration in the area of initial activation and aortic blood flow under electrical pacing of different ventricular regions. Having a single ventricle and primitive, if any, conduction system, a fish heart presents a useful model for assessing the functional significance of electrophysiological nonuniformities.

Methods

Experiments were performed in wild caught Atlantic cod (n = 18). Ventricular unipolar electrograms were led from an epicardial sock and intramural plunge electrodes (24–64 leads simultaneously) connected to a custom‐made mapping system. In each lead, activation times (ATs) and repolarization times (RTs) were determined as dV/dt min during QRS complex and dV/dt max during T wave, respectively. Activation‐repolarization intervals (ARIs, surrogate for action potential durations) were calculated as ARI = RT‐AT. Aortic blood flow was measured with transit time flow meter.

Results

In sinus rhythm, the posterior wall near the atrioventricular junction was earliest to be activated (median ATs 9 [IQR 3–15] ms) and had the longest median ARIs (516 [IQR 430–580] ms). The most remote from this area regions had expectedly longer ATs (heart apex: 33 [IQR 29–44] ms; anterior base 33 [IQR 25–43] ms; both p<0.05 vs posterior wall) and also demonstrated shorter ARIs (heart apex: 482 [IQR 427–544] ms; anterior base 416 [IQR 390–497]; both p<0.05 vs posterior wall). Posterior wall pacing yielded a highest median aortic flow 47.3 [IQR 40.4–74.4] mL/min/kg. Apical and anterior basal pacing gave lower median aortic flow values (40.7 [IQR 29.0–49.2] and 29.7 [29.3–39.1] mL/min/kg, respectively; both p<0.05 vs posterior wall pacing).

Conclusion

Pump function of the Atlantic cod heart ventricle is associated with activation‐to‐repolarization relationship: the longer repolarization at the site of activation origin provides the higher cardiac output.

Support or Funding Information

The study was supported by by the Ural Branch of the Russian Academy of Sciences (Project AAAA‐A18‐118012290365‐2) and the Program for Fundamental Research of RAS (AAAA‐A17‐117012310154‐6).

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Differences in plasma membrane integrity may explain collapse of cardiac function in Antarctic notothenioids varying in thermal tolerance limits
Authors: Evans Elizabeth R , Farnoud Amir M , Crockett Elizabeth L
Published: June 2021

Antarctic fishes of the suborder Notothenioidei are noted for their narrow temperature tolerance, yet the physiological factors underlying their limited capacity to endure elevated temperatures are unknown. Previous work by our group indicates that cardiac function may, in fact, delineate thermal tolerance. For example, the hemoglobinless (i.e., icefish) Chaenocephalus aceratus experiences persistent ventricular asystole at 14.1°C while the red‐blooded Notothenia coriiceps experiences asystole at 16.7°C, corresponding with established CTmax (associated with loss of right response) temperatures of 13.9°C and 17.1°C, respectively. In the current study, we tested the hypothesis that failure of membrane integrity is associated with collapse of cardiac function. Plasma membranes were isolated from ventricle tissue in both fish species and liposomes were prepared by rehydrating extracted lipids with the self‐quenching fluorophore 5(6)‐carboxyfluorescein (CF). Membrane structural integrity was assessed by quantifying percent of CF leakage from liposomes warmed in 1°C increments over a range of 0°C to 20°C, compared with CF leakage upon complete liposome dissolution. At physiological temperature (0°C), liposomes prepared from membranes of C. aceratus were significantly more permeable with initial leakage of 31% extending to 42% at 20°C, while membrane leakage was 1.5‐times less in N. coriiceps, beginning at 21% and increasing to only 27% over the same temperature range (P = 0.015). Liposomes prepared from membranes of the icefish also demonstrated increased thermal sensitivity compared with liposomes prepared from the red‐blooded species. Membrane leak increased most significantly between 0°C and 5°C in the icefish (P < 0.001), while liposomes from the red‐blooded species experienced the greatest change between 0°C and 9°C (P < 0.001), reflecting a reduced resilience to thermal change for the membrane integrity of C. aceratus compared to N. coriiceps (P < 0.001). Our data indicate that physical properties of the ventricular plasma membranes may indeed play a role in setting thermal tolerance limits in Antarctic notothenioid fishes.

Support or Funding Information

Supported by NSF ANT 1341602.

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Biochemical verification of smoking cessation and the role of endothelin‐1: Impact on cardiovascular disease risk
Authors: Tingen Martha S , Sojourner Samantha J , Tucker Matthew A , Derella Cassandra C , Harris Ryan A
Published: June 2021

Introduction

Smoking is an independent risk factor for cardiovascular disease (CVD). Endothelin‐1 (ET‐1), a potent vasoconstrictor peptide that also increases CVD risk, is transiently elevated following smoke exposure and is associated with self‐reported smoking status. Whether biochemical verification (i.e. serum cotinine) of smoking cessation over time is associated with changes in circulating ET‐1 has yet to be determined.

Purpose

To examine the impact of smoking cessation on the relationship between cotinine and ET‐1 over time.

Methods

35 individuals (aged 36 ± 10 yr., BMI 28.0 ± 5.7 kg/m2), participated in a 3‐month smoking cessation program. Measurements of resting systolic and diastolic blood pressures (SBP and DBP), serum cotinine, and plasma ET‐1 were determined at baseline, and immediately (3 months) and long‐term (12 months) following the smoking cessation program. Serum cotinine, a prominent metabolite of nicotine, was measured using liquid chromatography with mass‐spectrometric detection and plasma ET‐1 via microfluidic colorimetric assay.

Results

A significant reduction was observed in serum cotinine from baseline to immediately (3 months) following smoking cessation (176.1 ± 122.5 ng/ml vs. 53.0 ± 91.2 ng/ml, p<0.001) and persisted out to 12 months (84.8 ± 96.9 ng/ml, p<0.001). Similarly, plasma ET‐1 was significantly lower at 3 months (1.84 ± 0.60 pg/ml, p = 0.003) and at 12 months (1.93 ± 0.80 pg/ml, p = 0.018) following smoking cessation compared with baseline (2.18 ± 0.66 pg/ml). A significant association was observed between baseline levels of cotinine and ET‐1 (r = 0.369, p = 0.029). Additionally, the change in cotinine at 12 months following smoking cessation was associated (r = 0.402, p = 0.034) with the change in ET‐1 at 12 months. Although not statistically significant, clinically meaningful reductions in SBP (−2.0 ± 2.4 mm Hg, p = 0.406) and DBP (−3.6 ± 1.9 mm Hg, p = 0.062) were observed at 3 months following smoking cessation.

Conclusion

Using biochemical verification of smoking status in smokers, the present study identified a relationship between serum cotinine and circulating ET‐1. The 3‐month smoking cessation program not only lowered serum cotinine, but also reduced circulating concentrations of ET‐1 and blood pressure. In fact, at 12 months following smoking cessation, the change in serum cotinine was significantly associated with the change in ET‐1. The long‐term improvement of CVD risk with smoking cessation may be in part through a reduction in circulating ET‐1; however, future studies are warranted to test this hypothesis.

Support or Funding Information

Funding Provided by the Georgia Cancer Center

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
The Effect of Cardiorespiratory Fitness on Lipoprotein Particles in Midlife Women
Authors: Serviente Corinna , Chalvin Melody , Witkowski Sarah
Published: June 2021

Cardiovascular disease (CVD) risk accelerates in midlife women. Although lipoprotein cholesterol is a risk factor for CVD, increasing evidence suggests that lipoprotein particles may be more related to cardiovascular health. High cardiorespiratory fitness is associated with better lipoprotein particle profiles in men; however, little research has evaluated the effects of cardiorespiratory fitness on lipoprotein particles in midlife women.

PURPOSE

To evaluate the influence of cardiorespiratory fitness on lipoprotein particle profiles in healthy midlife women.

METHODS

The concentration, size, and subtype of high‐density (HDL), low‐density (LDL), very‐low density (VLDL), and intermediate density (IDL) lipoprotein particles was evaluated, along with the number of chylomicrons and triglycerides using nuclear magnetic resonance spectroscopy (LabCorp) in healthy high (n = 25, VO2peak = 46.4 ± 1.6 ml/kg/min, age = 55.8 ± 1.2 yr) and low‐fit (n = 13, VO2peak = 29.1 ± 1.0 ml/kg/min, age = 54.8 ± 1.8 yr) perimenopausal and postmenopausal women. A standard lipoprotein cholesterol profile was also assessed. Differences between high and low‐fit women were evaluated with independent t‐tests or Mann‐Whitney tests. Data are presented as mean ± SEM.

RESULTS

High‐density lipoprotein cholesterol was higher in high compared to low‐fit women (88.6 ± 2.9 vs. 74.7 ± 5.1 mg/dl, p = 0.015), while triglycerides and low‐density lipoprotein cholesterol concentration did not differ based on fitness (p>0.05). Compared to low‐fit women, high fit women had larger HDL particles (10.1 ± 0.1 vs. 9.7 ± 0.1 nm, p = 0.005), and a greater concentration of large (14.8 ± 0.7 vs. 11.0 ± 0.9 mmol/L, p = 0.002), and medium (12.9 ± 0.8 vs. 8.4 ± 0.8 mmol/L, p = 0.002) HDL particles. High‐fit women had larger LDL particles (21.7 ± 0.1 vs. 21.3 ± 0.1 nm, p = 0.005), and a greater concentration of large LDL particles (623.1 ± 32.8 vs. 500.2 ± 52.6 nmol/L, p = 0.045) and medium VLDL particles (10.6 ± 1.2 vs. 6.5 ± 1.6 nmol/L, p = 0.044) compared to low‐fit women. Conversely, low‐fit women had more small VLDL (29.9 ± 2.8 vs. 18.2 ± 2.5 nmol/L, p = 0.007), small HDL (15.4 ± 1.6 vs. 10.2 ± 1.1 mmol/L, p = 0.002), and small LDL particles (311.5 ± 44.7 vs. 145.5 ± 31.4 nmol/L, p = 0.001) compared to high‐fit women.

CONCLUSION

These data indicate that in healthy midlife women, high cardiorespiratory fitness may positively influence lipoprotein particle sizes and concentrations, and that many of these differences are not apparent from a standard lipid profile.

Support or Funding Information

American College of Sports Medicine Foundation Doctoral Student Research Grant (Serviente), National Institute on Aging Grant T32‐AG049676 (Pennsylvania State University), University of Massachusetts Amherst Provost's Undergraduate Research Fellowship (Chalvin).

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
The modified method of preparation of teaser stallion for the detection of the estrus in mare in horse herd farming
Authors: Anipchenko Polina , Korochkina Elena , Kramskaya Mary , Stekol'nikov Anatolij , Nikitkina Elena , Bazhenova Nataliya , Nikitin Georgiy
Published: June 2021

The purpose of the study was a modification of the method of preparation of teaser stallion by plastic surgery on the movement of the penis to the perineum of stallion for detection of the estrus in mare in horse herd farming. The study subject was a six‐year stallion with a balanced type of nervous system, the method was an operation in the area of the external genitalia of stallion. The preoperative preparation of the stallion consisted of analgesia and sedation, felling and fixing of the stallion, sanitization of the external genitalia and the preparation of the surgical field. The operation was as follows: in the preputial sheath injected a modified two‐part crutch (Russian patent №123660) caudally toward the perineum. The end of the caudal part of crutch was bandaged. Skin, fascia and connective tissue incision in perinea region were discissed. One end of the bandage was tied to the head of the penis, it was taken out to the crotch by the caudal part of crutch, behind the scrotum. Another part of crutch was taken in the cranial direction. bead joints were put in a wound to close the surgical wound, and then the wound was treated with liniment of synthomycin. The removal of sutures was performed in 10–14 days after the surgery. Two weeks later, the stallion was used to detect estrus in mares. There was developed a technique of modified, aseptic, less labor‐consuming method of preparation of a teaser stallion for estrus detection in mares in horse farming.

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
EXERCISE AND SEX IMPACT HEPATIC BILE ACID METABOLISM AND FECAL EXCRETION
Authors: Franczak Edward , Maurer Adrianna , Thyfault John
Published: June 2021

Exercise can improve metabolic outcomes associated with obesity including hepatic steatosis, however, precise mechanisms are not fully established, nor is the impact of sex. In this study we tested the hypothesis that exercise (via voluntary wheel running (VWR)) would increase expression of hepatic genes controlling cholesterol (Chol) and bile acid (BA) synthesis, and increase fecal BA excretion in male and female C57BL/6 mice providing a mechanism for diverting hepatic acetyl‐CoA away from de novo lipogenesis and towards fecal excretion. A time restricted feeding paradigm was also examined because nutrient availability (fed vs. fasting) impacts the Chol/BA pathway and may impact the capacity for VWR to modulate liver metabolism. Male and female, eight‐week old mice were randomly assigned to one of the following treatment groups (n = 8/group) while consuming a chow diet: sedentary plus ad libitum access to food (SED‐AL), sedentary plus overnight food restricted (SED‐OFR), voluntary wheel running ad libitum access to food (VWR‐AL), and voluntary wheel running plus overnight food restricted (VWR‐OFR) for a period of 4 weeks. Additionally, half of the mice in each group were either fed or fasted immediately prior to tissue collection. Females displayed across the board higher fecal bile acid concentration and higher hepatic gene expression for ACLY, CYP7A1, HMGCR, and FXR compared to males regardless of treatment condition. VWR only increased fecal BA concentration in fed females (VWR‐AL) while the effects of VWR and feeding status on hepatic expression of ACLY, CYP7a1, and HMGCR were mixed and largely insignificant compared to the male vs. female differences. Females had lower serum cholesterol and triglyceride levels. Exercise reduces susceptibility for hepatic steatosis, and female rodents are known to be protected against steatosis and these results suggest that these effects are associated with increased fecal BA excretion and/or an upregulation of Chol/BA synthesis gene expression.

Support or Funding Information

VA Merit Review grant (1I01BX002567‐01) (JPT)

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Total Expired Non‐Metabolic VCO2 and VCO2 Recovery Kinetics as Predictors of Performance Fatigability During Exercise
Authors: Wooten Liana C , Aldhahi Monira I , Keyser Randall E
Published: June 2021

Purpose

The severity of performance fatigability (PF) and the capacity to recover from activity are each profoundly influenced by skeletal muscle energetics, specifically the ability to buffer fatigue‐inducing ions produced as a result of anaerobic metabolism. The mechanisms responsible for buffering these ions results in the production of non‐metabolic carbon dioxide (CO2) that can be measured as expired CO2 (VCO2) during cardiopulmonary exercise testing (CPET). Yet, the relationships between PF and both total expired non‐metabolic (NMVCO2) and the capacity to recover from activity have yet to be investigated.

Methods

7 healthy subjects (30.71 ± 5.12 years) completed both a maximal and submaximal CPET on separate days, each followed by a 10‐minute recovery and 10‐minute walk test. Oxygen consumption (VO2) and VCO2 on and off‐kinetics (transition constant‐Kt and oxidative response index‐ORI), NMVCO2, and PF severity scores were measured. Data were analyzed using Pearson's correlations and regression analyses. Statistical significance was set at p<0.05.

Results

NMVCO2 accumulation and VCO2 off‐kinetic ORI accounted for 93% of the variance of PF severity scores (r2 = 0.932; p = 0.012). Measures of VCO2 off‐kinetics following both maximal (ORI r2 = 0.932, p < 0.001; Kt r2 = 0.919, p < 0.001) and submaximal (ORI r2 = 0.928, p < 0.001; Kt r2 = 0.955, p < 0.001 ) CPET and NMVCO2 (r2 = 0.614, p = 0.0371) were better predictors of PF than traditional measures of VO2 (VO2 peak r2 = 0.388, p = 0.135; AT‐VO2 r2 = 0.297, p = 0.206).

Conclusion

Previous studies investigating relationships between cardiopulmonary variables and PF have traditionally utilized measures of VO2. The current study demonstrates that measures of VCO2 may be more predictive of PF and its clinical manifestations. Furthermore, these measures were able to better predict PF even following submaximal testing presenting a less strenuous clinical measure of PF for those populations in which maximal exercise testing may be contraindicated.

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Effect of All‐extremity High‐Intensity Interval Training vs. Moderate‐Intensity Continuous Training on Arterial Stiffness and Wave Reflection in Adults with Type 2 Diabetes
Authors: Lim Jisok , Hwang Chueh‐Lung , Kim Han‐Kyul , Yoo Jeung‐Ki , Handberg Eileen M , Hwang Moon‐Hyon , Nichols Wilmer W , Petersen John W , Holmer Brady J , Lapierre Stephanie S , Sakarya Yasemin , Leey Casella Julio W , Cusi Kenneth W , Christou Demetra D
Published: June 2021

Aging and type 2 diabetes (T2D) are associated with arterial stiffening and altered wave reflection, which increase the risk for cardiovascular disease (CVD). Aerobic exercise training is known to reduce CVD risk but the most effective exercise regimen for improving arterial stiffness and wave reflection in middle‐aged and older adults with T2D has not been established. The purpose of this study was to compare the effects of all‐extremity high‐intensity interval training (HIIT) vs. moderate‐intensity continuous training (MICT) on arterial stiffness and wave reflection in middle‐aged and older adults with T2D. Forty‐nine sedentary middle‐aged and older adults with T2D (46 to 78 yrs; 63 ± 1 yrs; mean ± SE), free of CVD, were randomized to HIIT (n = 18), MICT (n = 16), or non‐exercise control group (CONT; n = 15). Isocaloric HIIT and MICT were performed on a non‐weight‐bearing all‐extremity ergometer (Airdyne, Schwinn), 4 days/week for 8 weeks, under supervision. HIIT consisted of alternating intervals of 4 × 4 mins at 90% peak heart rate (HRpeak) and 3 × 3 mins at 70% HRpeak, while MICT consisted of 32 mins of continuous exercise at 70% HRpeak. Both HIIT and MICT were preceded by a 10‐min warm‐up and followed by a 5‐min cool down at 70% HRpeak. Applanation tonometry (SphygmoCor, Atcor) was used to measure at pre‐ and post‐intervention arterial stiffness (carotid‐femoral pulse wave velocity; cfPWV) and aortic wave reflection characteristics including augmentation index normalized at heart rate of 75 beats/min (AIx@75). Following the 8‐week intervention, cfPWV remained unchanged (HIIT: 10.2 ± 0.5 vs. 9.8 ± 0.4 m/s; MICT: 10.7 ± 0.7 vs. 10.3 ± 0.6 m/s; CONT: 10.3 ± 0.8 vs. 10.3 ± 0.9 m/s; pre‐ vs. post‐intervention; P = 0.5 for group × time interaction). AIx@75 decreased in response to HIIT but did not change in response to MICT and CONT (HIIT: 24.8 ± 1.6 vs. 21.8 ± 2 %, P = 0.008; MICT: 24.3 ± 2.5 vs. 23.4 ± 2.6 %, P = 0.4; CONT: 25 ± 1.8 vs. 26.9 ± 1.6 %, P = 0.1; pre‐ vs. post‐intervention; P = 0.013 for group × time interaction). In conclusion, 8 weeks of all‐extremity HIIT, but not MICT, improved wave reflection but not arterial stiffness in middle‐aged and older adults with T2D. Whether performing all‐extremity HIIT and MICT over a longer duration than 8 weeks may result in arterial destiffening in middle‐aged and older diabetic patients remains to be investigated.

Support or Funding Information

This work was supported by National Institute of Aging grant AG050203 to DDC.

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
The Effect of Leg Fidgeting During Sitting on Glycemic Control in Obese Subjects – A Pilot Study
Authors: Pettit‐Mee Ryan J. , Ready Sean T. , Liu Ying , Padilla Jaume , Kanaley Jill A.
Published: June 2021

Background

Prolonged sitting is associated with glycemic excursions, which are likely more pronounced within individuals with risk factors for cardiovascular disease or type 2 diabetes. Strategies to minimize inactivity during sitting are needed to offset its consequences. While chair‐based fidgeting can increase energy expenditure above basal resting metabolic rate, the effect of this minimal amount of physical activity on glycemic control during prolonged sitting has not been investigated. Therefore, the purpose of this ongoing clinical trial is to assess the effect of leg fidgeting during prolonged sitting on glycemic control in obese individuals.

Design

Four obese women (43 ± 15 years; BMI = 35 ± 5.9 kg/m2) participated in a randomized cross‐over design study involving two experimental visits. Overnight‐fasted subjects sat in an office chair, ingested a 75 g glucose beverage, and then either refrained from leg movement or performed continuously repeated bouts of bilateral leg fidgeting (2.5 mins of leg fidgeting followed by 2.5 mins of rest) for the next three‐hours. Intravenous blood glucose sampling occurred throughout. Accelerometer data from one leg and popliteal artery blood flow measurements were recorded during the sitting period.

Results

Leg fidgeting resulted in increased accelerometer counts compared to no leg fidgeting (~16‐fold) as designed. In conjunction, leg fidgeting increased popliteal artery blood flow (P<0.05). Each bout of leg fidgeting resulted in elevated blood flow that normalized after 36 seconds (P<0.05) following leg fidgeting cessation. Despite these indicators of increased leg movement and metabolic demand, blood glucose total and incremental area under the curves were not significantly lowered with bilateral leg fidgeting. Blood Glucose concentrations at any time‐point were not different between conditions.

Conclusions

Leg fidgeting is not a sufficient stimulus to improve blood glucose concentrations in obese individuals during prolonged periods of physical inactivity, i.e. prolonged sitting. Further investigation is needed to assess more effective physical activity modalities and minimum thresholds of physical activity during sitting to improve blood glucose levels.

Support or Funding Information

Institutional support.

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Murine Live Bladder Tissue Model to Study the Microvasculature Properties and Function In Situ
Authors: de Sousa Loreto Aresta Branco Mafalda , Taylor Kirsti D. , Bowen Jenna L. , Peppiatt‐Wildman Claire M. , Wildman Scott S.P.
Published: June 2021

Regulation of microvascular blood flow in the bladder has historically been associated with regulation by pre‐capillary arterioles and more recently to post‐capillary venules. Although pericytes are known to regulate capillary vessel diameter in various capillary beds (e.g. brain, retina, heart and kidney), their role in regulating bladder capillary diameter remains controversial.

We have developed a mouse full‐thickness live bladder tissue model in which the microvasculature of the mucosa can be visualised in situ, enabling the regulation of suburothelial capillary diameter to be investigated. Bladder tissue viability was first investigated by fluorescence imaging of tissue labelled with Hoechst and propidium iodide to determine the live to dead cell ratio. Data indicated that tissue was viable in situ for up to 5 hours (>60%; P>0.05; n = 3 per time point). Real time DIC images of live tissue sections were collected for all experiments in which live tissue was exposed to vasoactive agents to investigate the pericyte‐mediated regulation of capillary diameter. Images were analysed off line and vessel diameter was measured at both pericyte and non‐pericyte sites along a capillary for each experiment. Angiotensin II (100 nM) and endothelin I (1 nM) evoked a pericyte‐mediated vasoconstriction of suburothelial capillaries at pericyte sites (13.3 ± 5.8%, 22.0 ± 9.7%) that was significantly greater (p<0.05, n = 6 per drug) than that measured at non‐pericyte sites (3.2 ± 2.7%, 6.0 ± 3.4%). Prostaglandin E2 (30 μM) evoked a pericyte‐mediated dilation of capillaries (12.1 ± 2.6%) that was significantly greater than that measured at non‐pericyte sites (2.3 ± 2.3%, p = 0.03, n = 3).

In this study we therefore demonstrate that suburothelial capillary pericytes act to regulate capillary diameter in response to agents previously reported to regulate capillary beds of other organs. This indicates that in addition to smooth muscle‐mediated regulation of upstream vessels in the bladder, spatial regulation of capillary diameter downstream of these vessels also occurs in the bladder.

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Microvascular Blood Flow Response to Hyperinsulinemia in Type 2 Diabetic Rats
Authors: Shogan Hamza , Russell McEvoy Gaylene M , Fraser Graham M
Published: June 2021

Objective

Chronic hyperglycemia is a defining feature of type 2 diabetes (T2D) that has been implicated in impaired microvascular structure and function. We aim to quantify the effect of hyperglycemia on local hemodynamic changes and spatial redistribution of blood flow in skeletal muscle capillary networks in response to hyperinsulinemia in an animal model of T2D.

Methods

Four 12‐week‐old Zucker Diabetic Fatty (ZDF) rats (2 lean, 2 obese) were fed a high fat diet (Purina 5008), acclimatized in animal quarters, and randomly selected on the day of experiment. Animals were anesthetized with sodium pentobarbital; cannulas were placed into the left common carotid and right jugular vein for systemic monitoring, anaesthetic administration and fluid resuscitation; animals were then tracheotomized and mechanically ventilated. Animals were maintained at 37□for the duration of the experiment and data collection. The right Extensor Digitorum Longus (EDL), a muscle of the lower‐hind limb, was isolated, and the distal tendon was cut to reflect the belly of the muscle over the objective of an Olympus IX‐73 microscope. Intravital videos of the microcirculation were recorded in 4–6 microscopic fields at multiple focal planes to capture blood flow in discrete capillary networks during baseline conditions. Euglycemia was achieved through intravenous infusion of insulin (2000 mU/kg/hr) and glucose (500 mg/kg/hr) until 3 stable blood glucose readings between 5 – 7 mM were made. Euglycemia was maintained while recordings were repeated in the same microscopic fields acquired during baseline.

Results

Resting blood glucose concentrations were 6.9 ± 0.4 mM for lean and 17.9 ± 1.2 mM for obese animals. At euglycemia, lean animals were brought to blood glucose levels of 6.3 ± 0.1 mM and obese to 6.2 ± 0.9 mM; mean glucose infusion rates were 28.9 ± 2.9 mg/kg/min for lean and 1.8 ± 2.1 mg/kg/min for obese animals. At baseline, mean capillary red blood cell (RBC) velocities were 233.0 ± 28.9 vs. 263.1 ± 24.2, hematocrits were 19.9 ± 4.3 vs. 32.9 ± 4.8, and RBC supply rates were 15.9 ± 1.3 vs. 21.9 ± 1.4 in lean and obese animals respectively (n = 525 capillaries). During hyperglycemia lean animals showed an 33% increase in RBC supply rate while obese animals showed a 25% decrease (n = 357 capillaries).

Conclusion

Hyperglycemia in control animals caused a marked increase in RBC supply rate in skeletal muscle tissue which may be an adaptive mechanism to enhance glucose uptake. This capillary flow response appears to be impaired in obese ZDF animals that share many characteristics with human T2D.

Support or Funding Information

This project was supported by a Medical Research Fund grant to GM Fraser from the Faculty of Medicine, Memorial University of Newfoundland.

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Towards a Multi‐Scale Model of Ventilation‐Perfusion Matching
Authors: Marquis Andrew D , Beard Daniel A , Pinsky David J
Published: June 2021

Ventilation‐Perfusion (V/Q) matching is a critical determinant of efficient gas exchange in the pulmonary circulation. The regulatory mechanisms that control V/Q matching under normal and pathological scenarios are incompletely understood. In this study we present the derivation and validation of a multi‐scale computer model of hemodynamics and gas exchange accounting for the fractal‐like pattern of pulmonary vascular branching, mechanical coupling of blood‐tissue interactions, gas exchange, hemoglobin biochemistry, and vasoregulatory mechanisms. By simulating the regional distribution of V/Q ratios, this model serves as an in‐silico platform to test and refine hypotheses regarding the contributions of vasoregulatory mechanisms to regional perfusion and V/Q matching in the lung. Figure 1 depicts the various model “blocks” and how they are interconnected. The complete model is formulated as an algebraically constrained system of ordinary and partial differential equations and is parameterized to represent function in an adult Sprague Dawley rat. Block (A) illustrates the whole‐lung vascular network model. The network geometry is generated by a space‐filling algorithm and is validated by comparing anatomical predications (length, radius, and connectivity) to morphometric data (from existing literature). Block (B) shows how the mechanics of each vessel segment is represented as a lumped system. Mechanics are validated by comparing model predictions to macro‐scale pressure‐flow relationships and pulmonary artery pressure waveforms (from existing literature and our own in vivo studies). Block (C) depicts a representative gas exchange unit. Block (D) portrays oxygen‐sensitive vasoregulatory mechanisms that have been implicated in the maintenance of pulmonary vasomotor tone. Model simulations illustrate that perfusion heterogeneity is governed by the geometry of the vascular tree, and local interaction between alveolar and vascular pressures. Moreover, conducted vascular responses (hypoxic pulmonary vasoconstriction, and the hypoxia‐mediated/mechanically‐transduced release of ATP from red blood cells) modulate the redistribution of blood flow in response to pathological insults such as a pulmonary embolism. Taken together, our results suggest that more homogenous blood flow distributions increase the bulk oxygen content entering the systemic circulation.

Support or Funding Information

NIH/NINDS R01 NS087147

NIH/NHLBI R01 HL127151

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Ectopic Cardiogenic Transcription Factor Expression Augments the Anti‐fibrogenic Activity of Administered Cardiac Mesenchymal Stromal Cells in a Model of Chronic Ischemic Cardiomyopathy
Authors: Heidel Justin Scott , Fischer Annalara , Sadri Ghazal , Tang Xian‐Liang , Wu Wen‐Jian , Uchida Shizuka , Stowers Heather , Bolli Roberto , Moore Joseph
Published: June 2021

Preclinical studies suggest that donor cell cardiomyogenic lineage commitment may be an important determinant of the efficacy of cardiac mesenchymal stromal cell (CMC) therapy; however, to what extent myogenic commitment influences CMC cardiac reparative capacity, as well as the underlying mechanisms by which they promote cardiac functional recovery remains poorly defined. In the current study we examine the consequences of enhanced cardiomyogenic lineage commitment on CMC cardiac reparative capacity in vivo and paracrine signaling potency in vitro, via ectopic expression of core cardiogenic transcription factors GMT (GMT: GATA4, MEF2C, and TBX5). Rat CMCs transduced with a tricistronic lentiviral construct harboring GMT coding sequences, or green fluorescent protein (GFP) control, were intramyocardially delivered in a rat model of chronic ischemic cardiomyopathy 30 days after a reperfused myocardial infarction. Indices of cardiac function were assessed by echocardiography and left ventricular (LV) Millar conductance catheterization 35 days after treatment. Infarct size and myocardial collagen deposition were enumerated in coronal‐dissected, cardiac tissue sections by Masson's trichrome or picrosirius red staining, respectively. Cytokine array analyses and in vitro cardiac fibroblast activation assays were performed using conditioned medium (CoMed) derived from either GMT or GFP CMCs, to respectively assess cardiotrophic factor secretion and anti‐fibrogenic paracrine signaling potential. Compared to GFP controls, GMT CMCs exhibited superior ability to attenuate LV systolic dysfunction and myocardial fibrosis in vivo. Proteome cytokine array analyses of CoMed revealed enhanced expression of cytokines with GMT CMCs that function in pathways that regulate matrix remodeling and collagen catabolism. Further, CoMed harvested from GMT CMCs more robustly inhibited Col1A1 synthesis in TGFβ1 activated cardiac fibroblast assays in vitro, compared to that of GFP CMCs. These results provide direct evidence that CMC myogenic lineage commitment biases cardiac repair and, further, that enhanced anti‐fibrogenic paracrine signaling potency may underlie, in part, their improved therapeutic utility.

Support or Funding Information

National Institutes of Health Grant R01 HL141081

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
K475E PRKAG2 Mutation: Cardiac Phenotype and Targeted Therapy Using Rapamycin
Authors: Tseng Yi‐Tang , Wang Zhengke , Padbury James , Phornphutkul Chanika
Published: June 2021

Background

We identified a novel mutation (K475E) in PRKAG2, coding for protein kinase AMP‐activated non‐catalytic subunit γ2, during a 27‐week prenatal ultrasound. A hypertrophic cardiomyopathy (HCM) phenotype was later confirmed. We have demonstrated in vitro that the K475E mutation led to increases in cardiomyocytes size and area which can be reversed by rapamycin. We have developed transgenic mouse lines with cardiac‐specific expression of the human wild type (TgWT) or K475E mutant (TgK475E) PRKAG2. The TgK475E mice exhibit many human PRKAG2 HCM phenotypes, including cardiac hypertrophy, glycogen overload and sudden death.

Objective

To characterize K475E‐induced cardiac phenotype in vivo and develop a targeted therapy using mTOR inhibition strategy for PRKAG2 mutation‐induced HCM.

Methods

Cardiac hypertrophy was monitored and cardiac glycogen levels were measured at several developmental stages. Neonatal mice (2‐wk old) were treated daily with vehicle or rapamycin (2 mg/kg, ip) for 4 weeks. Cardiac function was monitored longitudinally by echocardiography.

Results

Hypertrophy in TgK475E mice was confirmed. Histology revealed large vacuoles and high glycogen content in TgK475E myocytes throughout the ventricles. Echocardiography confirmed that LV mass dramatically increased in TgK475E mice starting from 5 weeks of age. Daily rapamycin treatment for 2 weeks dramatically decreased 1) cardiac hypertrophy and 2) glycogen overload in TgK475E mice. These beneficial effects of rapamycin were significantly tempered, however, when we switched to an alternative dosing regimen (one ip injection/3 days) of rapamycin.

Conclusion

The new transgenic mouse model reflects the early onset phenotype of the K475E mutation‐induced HCM in humans. The mTOR signaling pathway is involved in K475E induced HCM. Moreover, the mTOR inhibition strategy as targeted therapy for PRKAG2 induced HCM is effective and should be studied further.

Support or Funding Information

This study was supported by NIH P30GM114750 and the Oh‐Zopfi Research Award, Women & Infant's Hospital.

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
OxPCs‐Mediated Lipid Metabolic Responses in Cardiomyocytes as well as During Ischemia Reperfusion Injury
Authors: Bagchi Ashim K , Surendran Arun , Ravandi Amir , Jassal Davinder , Singal Pawan K
Published: June 2021

Oxidized phospholipids (OxPLs) promote inflammation as well as low density lipoprotein (LDL) uptake through its receptor (LOX‐1) in a variety of physiological and pathological states. We investigated whether the proinflammatory effect of OxPL, generated during stress conditions such as ex‐vivo exposure to POVPC (1‐Palmitoyl‐2‐(5‐oxovaleroyl)‐sn‐glycero‐3‐phosphorylcholine), a derivative of oxidative phosphatidylcholines (OxPCs) of OxPL family and global heart ischemia/reperfusion (I/R), is through the activation of LOX‐1 as well as toll‐like receptor‐2 (TLR‐2). In this study, isolated cardiomyocytes exposed to POVPC as well as isolated rat hearts subjected to global I/R were analyzed. OxPCs‐mediated‐oxidative stress (OS), caused LOX‐1 activation and altered lipid homeostasis. There was an upregulation of TLR2 expression in these conditions, suggesting that TLR2‐mediated inflammation is through LOX1. Furthermore, phosphorylation of sterol regulatory element binding protein 1c (SREBP 1c) was also found be increased due to an increase in OxPCs levels, which is also promoted OS and cell death. On the other hand, LOX‐1 activation also upregulated SREBP1c‐mediated TGF‐βRII expression causing fibrosis. Out of 80 fragmented and non‐fragmented OxPCs followed in a heatmap analysis, 24 in cardiomyocytes and 25 in heart were significantly higher in these stress conditions. Eight (8) of the OxPCs were shared between cardiomyocytes and hearts (FDR < 0.001). Interestingly, one specific fragmented OxPC i.e. 1‐palmitoyl‐2‐azelaoyl‐sn‐glycero‐3‐phosphocholine (PAzPC) among 8 shared OxPCs, was common in both stress conditions. However, a second major fragmented OxPC i.e. 1‐stearoyl‐2‐azelaoyl‐sn‐glycerophosphocholine (SAzPC) was also upregulated in the heart but not in the cardiomyocyte. It appears that cardiomyocyte‐specific; PAzPC and heart‐specific; SAzPC OxPCs may mediate abnormal lipid metabolic responses causing inflammation, apoptosis and fibrosis.

Support or Funding Information

Canadian Institutes of Health Research and Research Manitoba

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Cardiovagal baroreflex gain relates to sensory but not neurological level of spinal cord injury
Authors: Draghici Adina E , Taylor J. Andrew
Published: June 2021

The arterial baroreflex is a primary regulator of autonomic outflow to effectively regulate acute blood pressure changes. After a spinal cord injury (SCI), damage to the autonomic nervous system results in cardiovascular dysregulation. Higher level of injury results in greater loss of sympathetic control, while cardiac parasympathetic control remains intact regardless of injury level. Thus, it is possible that those with high level SCI, and hence extensive sympathetic disruption, will require greater cardiac parasympathetic compensation to control blood pressure. However, the effect of an SCI on cardiovagal baroreflex gain remains unclear. Baroreflex control of blood pressure in those with SCI has been reported to be greater, lesser, and no different compared to able‐bodied individuals. Moreover, the effect of injury level on baroreflex gain remains unclear as most studies that examined the effect of lesion level treated it as a discrete variable – high, usually cervical level lesions, and low, usually thoracic level lesions. Therefore, we assessed baroreflex sensitivity using the neck chamber techniques in those with SCI (N = 29) across a range of injury levels (neurological level of injury C1 – T10, sensory score C4 – S4/5), within 2 years of injury, and compared them to able‐bodied (N = 14). Injury level was assessed by both neurological level of injury and sensory score. We assessed baroreflex gain during 5 trials of 4 levels of neck chamber pressure (corresponding to −15, −25, −35, and −45 mmHg). We found no difference in baroreflex gain between those with SCI and able‐bodied (p>0.1). Neurological level of injury was not correlated to baroreflex gain, but sensory score and resting RR‐interval were (r = 0.47, p<0.01; r = 0.57, p<0.01). Multiple regression showed that both sensory score and resting RR‐interval were strongly predictive of baroreflex gain (r2 = 0.47, p<0.01): gain increased with lower sensory score and higher resting RR‐interval. Moreover, baroreflex gain was not different between those with high and low neurological level of injury; but higher in those with lower compared to higher sensory score (both p<0.01). Hence, sensory score is more predictive of baroreflex gain than the widely used neurological level of injury. This might be understood in the context of vagal‐sympathetic accentuated antagonism: those with high level injuries have the lowest likelihood of intact cardiac sympathetic innervation depressing cardiac vagal responsiveness.

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.