bluuebunny/crossref_metadata_2025_split huggingface dataset:
The role of enzyme and substrate dependence in NO‐mediated vascular dysfunction with aging
Authors: Bisconti Angela Valentina , Broxterman Ryan Michael , Jarrett Catherine Lee , Shields Katherine Lori , Park Soung Hun , Thurston Taylor Scott , Vidal Daniela , Richardson Russell S 
Published: June 2021

The typical aging process results in arterial dysfunction, often attributed to a fall in nitric oxide (NO) bioavailability. The diminished efficacy of the enzyme responsible for NO production, endothelial nitric oxide synthase (eNOS), and the required substrate, extracellular L‐arginine, may play a role in age‐related vascular dysfunction. Supplementation of tetrahydrobiopterin (BH4), a cofactor which recouples eNOS, and chronic supplementation of L‐Citrulline (L‐Cit), which increases plasma L‐arginine, may both increase NO bioavailability. Therefore, this study sought to evaluate the role of increased eNOS activity or L‐arginine concentration alone, and the combination of both, in the NO‐mediated vascular dysfunction associated with advancing age. Eight old subjects (73 ± 6 yr) received BH4 (100 mg per kg wt) acutely and underwent a 7 day supplementation of L‐Citrulline (6 g per day). Vascular function was assessed with: brachial artery flow mediated dilation (FMD: %) and passive leg movement (PLM: blood flow ΔPeak and AUC). Assessments were performed with and without BH4, both before and after L‐Citrulline supplementation (Ctrl; BH4; L‐Cit; L‐Cit + BH4). PLM ΔPeak increased ≈35% and ≈27% in the BH4 and L‐Cit + BH4 conditions, respectively (p< 0.05). PLM AUC increased ≈114% (p< 0.05) in the L‐Cit + BH4 condition. No significant intervention‐induced changes in FMD were detected. Thus, age‐induced vascular dysfunction, as measured by PLM which is likely more NO mediated than FMD, appears to belimited to a greater degree by eNOS function than eNOS substrate. However, the combination of improved eNOS coupling with increased eNOS substrate results in the greatest enhancement in vascular function in this population.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Modeling the Effect of Pulmonary Vascular Flow Regulation on Oxygen Uptake
Authors: Roy Tuhin K , Secomb Timothy W 
Published: June 2021

Pulmonary oxygen uptake is affected by the transport characteristics of the alveolar‐capillary membrane as well as heterogeneity of pulmonary blood flow, both of which can limit the lung's capacity for oxygen transport as characterized by its effective diffusing capacity. In previous work, we showed that while under resting conditions the healthy lung has a high degree of tolerance for pulmonary flow heterogeneity, under conditions of exercise such flow heterogeneity can preclude the high levels of oxygen uptake necessary to meet tissue demand. The goal of the present study is to test the ability of hypoxic pulmonary vasoconstriction (HPV) to mitigate flow heterogeneity and enable adequate oxygen transport levels in the lung to meet tissue needs under conditions of exercise. A mathematical model of pulmonary oxygen uptake is used, in which flow heterogeneity is characterized by the coefficient of variation (CV) of pulmonary capillary blood flow. Assuming an initial lognormal distribution of blood flow with a high degree of heterogeneity, we simulate flow regulation in the cases of rest and exercise by adjusting pulmonary flow resistance in each vessel in accordance with previously published experimental data. The effect of HPV on vessel flow resistance is assumed to be characterized by a sigmoidal response dependent on the capillary oxygen tension, which is approximated as the mean of the venous and arterial values in each capillary. The results show a reduction in the effective CV from a baseline of 2.73 to 1.83 under resting conditions and to 0.66 in the case of exercise. The stronger reduction in heterogeneity under conditions of exercise corresponds to the need for greater flow regulation to minimize heterogeneity under conditions of physiologic stress. The predicted level of heterogeneity in exercise is in general agreement with our previous prediction of the upper limit of CV consistent with the levels of oxygen uptake in literature data for exercising humans. The results demonstrate the essential role of HPV to regulate flow and minimize heterogeneity under conditions of exercise and highlight the need for a functional pulmonary flow regulation mechanism under stressful or pathophysiological conditions.Support or Funding InformationSupported by NIH U01 HL133362.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Integrative Effects of Autophagy and Telomerase on Arteriolar Flow‐Mediated Dilation in Health and Coronary Artery Disease
Authors: Hughes William E , Beyer Andreas M , Gutterman David D 
Published: June 2021

Flow‐mediated dilation, (FMD) is manifest by arteriolar vasodilation in response to shear stress in an endothelium‐dependent manner. Nitric oxide (NO) is the primary mechanism for FMD in health, while hydrogen peroxide (H2O2) is the dominant mechanisms of dilation in subjects with coronary artery disease (CAD). TERT, the catalytic subunit of telomerase, is responsible for maintenance of telomere length, and telomerase activity (TA) and is necessary to preserve physiological mitochondrial function under conditions of acute stress. Autophagy is a basic cellular recycling process, responding to unfolded proteins and damaged organelles. Both autophagy and TERT levels are downregulated in subjects with CAD. Inhibition of TERT in non‐CAD vessels reduces autophagy (Fig 1A), and switches the mechanism of dilation from NO to H2O2. Conversely, activation of TERT switches the mechanism of dilation from H2O2 to NO in CAD (Fig 1B.). We sought to examine whether autophagy and TA are part of the same pathway regulating microvascular FMD in healthy (non‐CAD) and CAD vessels. Human arterioles from discarded adipose tissue were isolated and prepared for videomicroscopy. Non‐CAD vessels were co‐incubated overnight with TA inhibitor (BIBR 1532; 10 μM) and an activator of autophagy (Trichostatin A, TSA; 100 nM). CAD vessels were co‐incubated with an inhibitor of autophagy (Bafilomycin A1, BAFA1; 10nM) and the transcriptional activator of TERT (AGS 499; 20 nM). Internal diameters were measured after graded increases in intraluminal pressure gradients (flow) in the presence/absence of a NOS inhibitor (L‐NAME; 100μM) or H2O2 scavenger (Peg‐Catalase, Peg‐Cat; 500 units/mL). Data are expressed as % maximal dilation. In vehicle treated vessels, the magnitude of FMD was similar between non‐CAD and CAD. Within CAD vessels, inhibition of autophagy prevented the activator of TERT (AGS) from switching the mediator of FMD from H2O2 to NO (AGS 499 + BAFA1: 84.4±9.4 vs. AGS499 + BAFA1 + L‐NAME: 92.6±6.1 vs. AGS499 + BAFA1 + Peg‐Cat: 19.1±14.0; Fig 2A, n = 3–5; P<0.05). Conversely, in non‐CAD vessels, activation of autophagy prevented the switch from NO to H2O2 typically seen during inhibition of TERT (BIBR + TSA: 86.4±9.2 vs. BIBR + TSA + L‐NAME: 36.3±12 vs. BIBR + TSA + Peg‐Cat: 73.8.9±9; Fig 2B, n = 3–5; P < 0.05,). Our data demonstrate that autophagy is distal to TERT in regulating the mechanism of FMD in human adipose arterioles and may serve as a final common pathway for determining the mechanism of FMD in human arterioles.Support or Funding InformationFunded by T32GM089586‐09 (WEH), R01‐HL133029‐02 (AMB), and R01‐HL135901‐02 (DDG)This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Endothelial Hba1 Regulates Exercise Fitness in Mice
Authors: Keller Alexander S , Brooks Steven , Islam Aditi , Keller T.C. Stevenson , Best Angela K , Murphy Sara , Page Henry Askew , Cortese‐Krott Miriam M , Yan Zhen , Ackerman Hans , Isakson Brant E 
Published: June 2021

Hemoglobin alpha (Hbα) is expressed from the Hba1 and Hba2 genes in the endothelium of resistance arteries, where it plays a vital role in regulating NO signaling by endothelial nitric oxide synthase (eNOS). We have previously shown that pharmacologic inhibition of the eNOS‐Hbα interaction reduces blood pressure, and that siRNA knockdown of endothelial Hba1 increases NO signaling in resistance arteries. We have created a genetically modified mouse model in which loxP sites flank the second and third exons of the Hba1 gene (Hba1fl/fl), and crossed these Hba1fl/fl mice with the Cdh5‐Cre/ERT2+line to produce an endothelial‐specific, tamoxifen‐inducible genetic model of Hba1 deletion (EC Hba1Δ/Δ). Similar to mice with global deletion of Hba1 (Hba1−/−), EC Hba1Δ/Δ mice display reduced Hbα expression in the endothelium of resistance arteries; however, EC Hba1‐Δ/Δ mice display normal red blood cell parameters in contrast to the anemic phenotype of Hba1−/− mice. EC Hba1Δ/Δ mice also display unaltered expression of other globins in the vascular wall of resistance arteries, as well as normal capillary density in fast‐twitch and slow‐twitch hindlimb muscles. We used a treadmill running test as a measure of acute endurance capacity to examine the role of endothelial Hbα in exercise hyperemia. EC Hba1Δ/Δ mice showed a significant reduction in endurance capacity as compared to Hba1fl/fl controls, equal to half the effect seen in Hba1−/− mice with constitutive loss of both vascular and RBC Hba1. We conclude that endothelial Hba1 plays an important role in vascular function and exercise performance.Support or Funding InformationAHA Pre‐Doctoral Award (ASK, TCSK); NIH NRSA (ASK, TCSK), NIH 5T32 GM008715 (ASK); NIH HL088554 (BEI); German Research Council DFG CO 1305/2‐1 (MMCK); NIH R01‐AR050429 (ZY), Support from NHLBI Intramural Funding (SB, HA)This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Human Coronary Micro‐artery Dysfunction is Associated with Structural and Smooth Muscle Cell Phenotypic Alterations
Authors: Borysova Lyudmyla , Ye Xi , Smart Nicola , Ascione Raimondo , Dora Kim A 
Published: June 2021

Autoregulation is compromised in patients with coronary heart disease. A lack of myogenic reactivity and endothelial dysfunction each contribute to a reduced ability to control blood flow within the coronary microcirculation. Little is known how coronary arterial smooth muscle structure and phenotype links to vascular reactivity.Right atrial appendage biopsies from consented patients undergoing valve replacement surgery, and from pigs were collected at clinical standards under general anesthesia. Human and porcine arteries from right atrial appendage samples were isolated and mounted for pressure myography. Confocal imaging established vasomotor responses, cellular viability, and immunohistochemical localization of proteins. The human study complies with the Helsinki Declaration and the animal study complies with the UK Animal (Scientific Procedures) Act, 1986.Here, we compared the structural features of human patient intra‐myocardial coronary arteries (IMCAs) with equivalently handled porcine IMCAs, representing healthy, juvenile controls. More than half the human IMCAs failed to develop ≥10% myogenic tone, even those in which constituent smooth muscle cells (SMCs) could adequately mobilize intracellular Ca2+required for contraction. 3D confocal revealed a novel, distinct layer of longitudinally‐arranged sub‐intimal SMCs (l‐SMCs) between the endothelium and the expected circumferentially‐arranged SMCs responsible for radial contraction (r‐SMC) in the majority of human and porcine IMCAs.Contractile function strongly correlated with SMC phenotype, with the synthetic markers L‐caldesmon and vimentin highly expressed in SMCs with poor contractile function, namely the human r‐SMCs and the porcine l‐SMCs. Thus, we propose that l‐SMCs retain an immature, synthetic phenotype in healthy vessels with functional r‐SMCs but, with loss of r‐SMC function in aged patients, l‐SMCs may play a reparative role and can adopt a contractile phenotype in an attempt to restore function and control myocardial perfusion. The role of l‐SMCs in maintaining the integrity of arterial function warrants further investigation.Support or Funding InformationThis work was supported by the British Heart Foundation (grant numbers FS/08/033/25111, FS/13/16/30199, IG/13/5/30431, PG/18/11/33552) and by the Oxford BHF Centre of Research Excellence (RE/13/1/30181).This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Loss of endothelial surface molecules in the central retinal artery and retina with methamphetamine
Authors: Lee Minsup , Leskova Wendy , Carter Patsy , Eshaq Randa , Harris Norman 
Published: June 2021

ObjectiveThe purpose of this study is to investigate the retinal effects of methamphetamine.IntroductionMETH, a highly addictive stimulant of neurotransmitters is associated with cardiovascular and neurological diseases. METH‐induced ophthalmic complications are also present but have been insufficiently investigated.Materials and methodsC57BL/6J mice were administrated progressively increasing doses of METH (0 to 6 mg/kg) by repetitive intraperitoneal injections for 5 days (4 times per day). Norepinephrine levels in plasma were measured by ELISA. Cross‐sections of the central retinal artery (CRA) and retina were stained with hematoxylin and eosin. Expression of various proteins was determined by immunostain and immunoblot in the CRA and retina.ResultsElevated norepinephrine levels in plasma were induced by METH (6.49±1.72 ng/mL, n=5), compared with saline treatment (1.38±0.48, P<0.001, n=5). After treatment of METH, the ocular pupil was dilated and retinal thicknesses of the outer nuclear layer, outer plexiform layer, inner nuclear layer, and inner plexiform layer were decreased. Platelet endothelial cell adhesion molecule‐1 (PECAM‐1) protein expression level was decreased in the CRA and retina of METH‐treated mice, along with the endothelial proteoglycans glypican‐1 and syndecan‐1. Moreover, a regulator of the extracellular matrix, membrane type 1 matrix metalloproteinase (MMP‐14), but not MMP‐2 and MMP‐9, was increased in the retina by METH treatment.ConclusionThese results suggest that METH administration is involved in retinal degeneration with a vascular loss of PECAM‐1 and the glycocalyx, and an increase of MMP‐14 in the CRA and retina.Support or Funding InformationThis work was supported by funding from the National Institute of Health (NIH) EY025632.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
A Novel Methodology to Assess Retinal Vascular Permeability in a Rodent Model of Diabetes
Authors: Allen Claire , Malhi Naseeb , Bates David , Arkill Kenton 
Published: June 2021

PurposeDiabetic retinopathy (DR) is a major complication of diabetes and is one of the leading causes of blindness worldwide. Treatment of DR can only be achieved through an enhanced understanding of disease pathogenesis. Structural, functional and biochemical studies cannot be carried out in human subjects and chemically induced diabetic rodent models that mimic the early developmental changes in DR and have become the gold standard. In combination with fundus fluorescein angiography (FFA) retinal abnormalities, non‐perfusion and vascular permeability can be assessed and in response to treatments over time.MethodsFFA was carried out in non‐diabetic and diabetic Norway Brown rats (250–300g) on days 0, 14, 21 and 28 using the Micron IV retinal imaging microscope (Phoenix Research Labs, CA). Animals received a single dose of PBS (n=6) or streptozotocin (STZ) i.p., 50mg/kg (n=6) and blood glucose levels were measured throughout. Video angiograms were quantitatively analysed for suboptical resolution microvascular permeability by using the arterioles as the measure for luminal concentration. In a separate subset of experiments primary human retinal endothelial cells (pHREC) were exposed to normo‐(D‐Mannitol, 30mM) or hyperglycaemia (D‐Glucose, 30mM) and probed for glycosaminoglycans (GAGs) heparan sulfate (HS), chondroitin sulfate (CS), and the tight junction marker ZO‐1.ResultsDiabetes was successfully induced in Norway Brown rats following a single dose of STZ (Blood glucose 28.4±2.6 mmol/L, day 28). By adapting Fick's Law retinal permeability (Ps, um.s^−1) was calculated and shown to significantly increase (p<0.05) for each time point, over the 28‐day period. To understand the mechanisms that may account for this increase in solute permeability across the retinal vessel wall we observed a significant decrease in sulphated GAG expression, more specifically HS (p<0.05) in pHREC exposed to hyperglycaemia versus normoglycaemia. In addition, the expression of the tight junction protein ZO‐1 significantly decreased in pHREC when exposed to hyperglycaemic conditions.ConclusionsRetinal vascular solute permeability can be accurately quantified in a rodent model of diabetes using the outlined methodology and mathematical quantification. Advanced quantitative assessments such as this could substantially contribute to a better understanding of the pathogenesis of DR and identify potential drugs for treatment.Support or Funding InformationMRCThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Insulin‐induced hypoglycemia directly affects the cerebral microvasculature in vivo
Authors: Evans Wesley R , Sakamuri Siva V. P. , Sperling Jared A. , Sure Venkata N. , Busija David W. , Mostany Ricardo , Katakam Prasad V. G. 
Published: June 2021

ObjectiveInsulin therapy for patients with diabetes mellitus (DM) carries the risk for acute hypoglycemia (HG). Evidence from human and animal studies has suggested a role for HG in the exacerbation of cardiovascular dysfunction accompanying DM. Specifically, animal studies have shown that recurrent HG promotes increased ischemic brain injury. Furthermore, HG has been shown to affect mitochondrial function in cultured endothelial cells. Therefore, we hypothesized that acute insulin‐induced HG directly affects the cerebral microvascular function in vivo.MethodsWild type C57Bl/6 mice were prepared for long term two‐photon microscopy by removing a 4mm diameter section of bone over the somatosensory cortex which was then sealed with a glass coverslip held in place with cyanoacrylate and dental acrylic. A custom titanium bar was added to the preparation for head fixation during imaging. During imaging sessions, the cerebral vasculature was visualized using FITC‐dextran 40kDa. Mice were imaged under hypoglycemia (63.2 +/− 8.2 mg/dL by imaging start) using 1–2 U/kg of Humulin‐R. Microvessels approximately 3–5μm in diameter were measured for diameter changes using ImageJ. Blood flow through cerebral microvessels was assayed using line scans over the vasculature to determine red blood cell (RBC) traffic and speed. Fluorescence intensity was also measured in ImageJ to determine any changes in BBB permeability.ResultsAcute hypoglycemia induces a vasodilatory effect in cerebral microvasculature (diameter increased by 10.0 +/− 1.7 %, N=7 mice, n=89 microvessels, vs. 1.751 +/− 1.0 % N=6 mice, n=134 microvessels, in saline controls, p = .0007). However, blood flow was not changed between groups (149.0 +/− 7.4 vs. 167.6 +/− 11.3 RBC/sec and 0.979 +/− 0.060 vs. 1.052 +/− 0.068 μm/ms). Additionally, acute hypoglycemia caused no noticeable changes in the permeability of the BBB indicated by the extravasation of FITC‐dextran.ConclusionsOur data show that acute HG causes noticeable changes in the in vivo cerebral microvasculature, however, we did not note any changes in blood flow, potentially due to cerebral auto regulation. We therefore conclude that insulin‐induced HG causes noticeable direct effects on the cerebral vasculature that may play a role in cerebro vascular impairments in DM.Support or Funding InformationNational Institute of Health: National Institute of General Medical Sciences, National Institute of Aging, and National Institute of Neurological Disorders and Stroke (Mostany: R01AG049821; Katakam: R01NS094834).This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Vascular‐cognitive Impairment after Chronic Experimental High‐thoracic Spinal Cord Injury
Authors: Jia Mengyao , Sachdeva Rahul , Wang Shaoxun , Yung Andrew , Zheng Mei Mu Zi , Lee Amanda HX , Leong Sarah , Kozlowski Piotr , Fan Fan , Roman Richard J. , Phillips Aaron A , Krassioukov Andrei V 
Published: June 2021

IntroductionCognitive impairment is present in 64% individuals with spinal cord injury (SCI), affecting their attention, memory, learning and studying abilities, which are essential for post‐injury rehabilitation and possible transition into community. Previous studies from our group have reported the presence of vascular‐cognitive impairment in SCI individuals. However, a direct link between SCI‐associated vascular dysfunction and cognitive deficits hasn't been established.ObjectiveTo designing a pre‐clinical model to investigate cardiovascular, cerebrovascular, and cognitive function following chronic high‐thoracic SCI.MethodsTwenty‐eight male Wistar rats were assigned to uninjured group (CON, n=14) and T3‐level spinal transection group (SCI, n=14). Fourteen weeks after injury, cognitive function and cerebral blood flow from both group were evaluated using novel object recognition test and magnetic resonance imaging (MRI) respectively. Moreover, in vivo and in vitro physiological assessments, as well as histological assessment in cerebral vasculature were conducted.ResultsOur animal model demonstrates autonomic disreflexia (AD) event (41.860 mmHg increase in systolic blood pressure) induced by colorectal distension, clinically relevant to unstable blood pressure following SCI. We conclude that chronic high‐thoracic SCI leads to 1) short‐memory loss (p=0.0225), 2) cerebral hypoperfusion (32% reduction in baseline cerebral blood flow, p=0.0277) and 3) cerebrovascular dysfunctions, including endothelial dysfunction associated with reduced endothelial TRPV 4 expression, and 70% increased collagen I deposition.ConclusionThis study provides evidence that vascular‐cognitive impairment occurs at chronic stage of SCI and highlighting TRPV 4 as a potential therapeutic target to improve post‐injury cognitive and cerebrovascular health.Support or Funding InformationCanadian Institute of Health Research, Heart and Stroke Foundation of CanadaThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.