bluuebunny/crossref_metadata_2025 huggingface dataset:
AT1 blockade decreases NADPH oxidase 2 content and increases insulin signaling in a model of insulin resistance
Authors: Popovich Irina , Rodriguez Ruben , Viscarra Jose , Vasquez-Medina Jose-Pable , Nishiyama Akira
Published: June 2021

Angiotensin II (Ang II) increases oxidant production through the activation of Nox2 during insulin resistance (IR). Angiotensin receptor blockers (ARB) improve IR in the peripheral tissue suggesting a link among Ang II receptor (AT1) activation, oxidative stress and development of IR; however, these relationships in the heart are not well described. To test the hypothesis that AT1 activation increases NADPH oxidase (Nox) content and oxidative damage, while impairing insulin signaling and antioxidant enzyme activities, we measured Nox2 and 4, insulin signaling proteins, oxidative damage and antioxidant enzyme activity in the heart of OLETF rats, a model of insulin resistance. After 6 wks of treatment, hearts were collected from 3 groups of rats: 1) lean‐strain controls (LETO), 2) OLETF (15 wks of age), and 3) OLETF + ARB. ARB treatment increased Akt (57%) and AMPK (27%) activation in the OLETF rats, as well as, recovery in the p85α and Glut4 content. Similarly, AT1 blockade decreased (33%) Nox2 content, and increased (36%) Nox4, associated with increased catalase (41%) and SOD (70%) activities. The results suggest that Nox2 activity is dependent on AT1 activation and promotes oxidative damage. Furthermore, the parallel increases in Nox4 and antioxidant enzyme activities in the heart suggest that Nox4 activation is important for signaling cardiac antioxidant enzyme activities to abate the Nox2‐induced damage.
GWAS nominated gene SH2B3 increases cardiac remodeling and inflammation associated with type 1 diabetes (T1D)
Authors: Flister Michael , Jia Shuang , Tsaih Shirng-Wern , Sarkis Allison , Zheng Sasha , Geurts Aron , Moreno-Quinn Carol , Lazar Jozef , Hessner Martin J , Jacob Howard
Published: June 2021

SH2B3 functions largely as a negative regulator of inflammation. The rs3184504 [T] allele of SH2B3 causes an R262W substitution that is associated with multiple inflammatory diseases, yet the effect of R262W on SH2B3 function and downstream target pathways is completely unknown. We found the homozygous SH2B3 rs3184504 [T] allele (referred to as TT) to be significantly associated with T1D [(P = 0.04; OR = 1.49 (95% CI: 1.02–2.19)] compared with rs3184504 [C] alleles (CC/CT). We tested the role of rs3184504 [T] by performing microarray analysis of peripheral blood mononuclear cells (PBMCs) to detect inflammatory factors in serum of SH2B3‐genotyped T1D patients (n=48) and controls (n=44). Compared with CC/CT, T1D patients with TT had 377 elevated genes, including many that are associated with T1D and cardiac remodeling (e.g., CCL2, IL1R2, CD36, and CCR5). RNAseq of PBMCs from SSSh2b3mut rats showed 534 elevated genes compared to WT, of which 84 corresponded to TT associated genes in T1D. SH2B3 associated genes were significantly enriched in multiple inflammatory pathways (e.g., NF‐κB, IL1β, IL6, TGFβ, and TNFα). Following aortic banding, SSSh2b3mut rats had higher interstitial fibrosis (7.0% vs 4.2%), 40% thicker LV walls, and 21% decrease in capillary density compared to WT. Collectively, we show that rs3184504 [T] alters SH2B3 function and elevates T1D associated inflammation. Support: NHLBI5R01HL089930 to HJJ.
Heart Rate Variability in Patients with Type 2 Diabetes Mellitus
Authors: Goit Rajesh Kumar , Khadka Rita , Sharma Sanjib Kumar , Limbu Nirmala , Paudel Bishnu Hari
Published: June 2021

Objective

To study heart rate variability (HRV) in patients with type 2 diabetic mellitus (T2DM).

Methods

HRV of 60 patients with T2DM and 30 controls were assessed. Resting ECG at spontaneous respiration was recorded for 5 minutes in supine position. The data are expressed as median (interquartile range). The p value <0.05 was considered statistically significant.

Results

All the time domain measures SDNN [26 (15.5–35) vs 36 (30–40.25) ms, p=0.002], RMSSD [25.9 (11.95–40.45) vs 36.65 (27.05–44.13) ms, p=0.002], NN50 [13.5 (1–70) vs 58 (15.5–86.5) count, p=0.002] and pNN50 [3.5 (0.23–21.83) vs 16.4 (4.45–27.63) %, p=0.002] were significantly lower in T2DM. In frequency domain, LF power [81 (32–148.75) vs 126 (85.25–237.75) ms2, p=0.007], LF power [28.8 (20.78–36.13) vs 36.05 (24.6–43.5) %, p=0.008], HF power [81 (16.75–187.75) vs 182.5 (121.5–281.75) ms2, p=0.001] and HF power [42.15 (27.73–50.65) vs 51.6 (43.58–62.05) %, p=0.001] were significantly lower in T2DM whereas LF nu [45.25 (35.28–63.93) vs 44.65 (33.7–65.35)] and LF/HF ratio [0.776 (0.543–1.13) vs 0.7005 (0.397–0.999)] were comparable. In Poincare plot, SD1 [18.5 (8.73–28.98) vs 26.2 (19.33–31.65) ms, p=0.003] and SD2 [37 (26.13–51.18) vs 48.6(39.63–56.15) ms, p=0.002] were lower in T2DM.

Conclusions

Patients with T2DM have reduced cardiovascular autonomic control especially parasympathetic control.
Hemoglobin expression at the myoendothelial junction regulates nitric oxide scavenging and vasomotor tone
Authors: Straub Adam , Lohman Alexander , Billaud Marie , Johnstone Scott , Dwyer Scott , Lee Monica , Schoppee-Bortz Pamela , Best Angela , Gaston Benjamin , Isakson Brant
Published: June 2021

Endothelial nitric oxide synthase (eNOS) localizes to the myoendothelial (MEJ), a discreet location where the endothelial cells (EC) and smooth muscle cells (SMC) make contact, however the regulation of eNOS‐derived NO at the MEJ remains unknown. Using a vascular cell co‐culture (VCCC) model, we isolated EC, MEJ, and SMC protein fractions and subjected them to isobaric tag for relative and absolute quantitation analysis coupled to mass spectrometry. From this analysis, we identified enriched expression of hemoglobin subunit alpha (Hbα) at the MEJ compared to EC or SMC fractions and show mRNA expression predominately in ECs. In multiple small arteries and arterioles (i.e. thoracodorsal artery (TD), mesentery), we found enriched expression of Hbα at the MEJ. Since Hbα has the capacity to scavenge NO, we performed a NO consumption assay and found that TD arteries or isolated MEJ fractions consumed a majority of the NO. Consistent with this data, EC‐specific knockdown of HBα using siRNA showed enhanced NO diffusion in TD arteries or in VCCCs compared to control or scrambled siRNA. EC‐specific knockdown of Hbα in pressurized TD arteries attenuated phenylephrine‐mediated constriction. Lastly, in isolated TD arteries or MEJ fractions, we found that Hbα co‐immunoprecipitates with eNOS. Collectively, these results suggest that Hbα at the MEJ is critical for NO signaling and regulation of vasomotor tone.
Role of BMP4 in eNOS uncoupling in type 2 diabetes
Authors: Youn Ji Youn , Cai Hua Linda
Published: June 2021

Bone morphogenic protein 4 (BMP4) is involved in atherosclerosis by activating proinflammatory responses and endothelial dysfunction. NADPH oxidase (NOX) has been suggested to have a role in BMP4 mediated endothelial dysfunction. Recently, we have found that NOX1 activation‐dependent uncoupling of eNOS represents the predominant source of reactive oxygen species production in the endothelium of streptozocin induced type 1 diabetes mellitus, leading to impaired endothelium‐dependent vasorelaxation. In the present study we aimed to test a role of BMP4 in eNOS uncoupling in type 2 diabetes mellitus (T2DM), and a potential role of one or more isoforms of NOXs in mediating this response. Levels of circulating BMP4 in plasma were found elevated in db/db mice, where eNOS was found significantly uncoupled. Electron spin resonance measurement of superoxide production implicated L‐NAME‐sensitive superoxide production in db/db mice, which was however absent in the wild‐type mice. Infusion of BMP4 inhibitor noggin‐1 into db/db mice (15 μg/kg/day, 4 weeks) in vivo completely attenuated uncoupling of eNOS. Direct exposure of cultured aortic endothelial cells to BMP4 (50 ng/ml for 24 hours) resulted in eNOS uncoupling. This response was abolished by supplementation of eNOS cofactor tetrahydrobiopterin precursor sepiapterin (10 μmol/L). Taken together, these data seem to demonstrate a novel role of BMP4 in mediating eNOS uncoupling in T2DM, which might partially underlie sustained oxidative stress, endothelial dysfunction and accelerated vascular complications in patients with T2DM.
Estrogen receptor dependence of lysyl oxidase expression and activity in cardiac fibroblasts
Authors: Voloshenyuk Tetyana G , Larkin Kimberly , Fournett Alyssa , Gardner Jason D
Published: June 2021

Lysyl oxidase (LOX) is a collagen crosslinking enzyme essential for the deposition of collagen. We investigated the mechanism of estrogen mediated increases of LOX expression in rat cardiac fibroblasts and the role of estrogen receptors (ER). Adult rat cardiac fibroblasts were treated with ER‐α (MPP) and ‐β (PHTPP) specific antagonists, and a general ER inhibitor (ICI 181780), then treated with estrogen for 48 hrs. LOX protein expression was analyzed by Western blot. LOX catalytic activity was measured by fluorometric assay of cell‐conditioned media. Estrogen (1 to 50 ng/ml) increased LOX protein expression (150–290% for active form and 210–310% for proLOX vs control; P<0.05). Estrogen also increased LOX activity in media (120–140% vs media from untreated). LOX activation by estrogen was prevented by ER‐α and ‐β blockade; however ER‐β antagonism had a greater effect, reducing LOX activity below that of control (75% versus control and ER‐α block; P<0.05). ER‐β blockade also had a greater effect on LOX protein expression (58% decrease for active LOX vs estrogen treated) than ER‐α inhibitor (25%). ICI also significantly decreased LOX protein expression. These data indicate that both ER‐α and ‐β are involved in estrogen induced upregulation of LOX expression and activity in rat cardiac fibroblasts, with ER‐β playing a more significant role (Louisiana Board of Regents LEQSF2009‐12‐RDA10 and AHA #11GRNT7700002).
Segment‐specific tissue factor expression in mouse lung vasculature
Authors: Bhattacharya Sunita , Emin Memet
Published: June 2021

In acute lung injury (ALI), pro‐coagulant responses remain undefined in extra‐alveolar versus alveolar vascular segments. Since endothelial vWf content is different in these segments, we considered pro‐coagulant responses might also differ. We determined surface expression of the coagulation initiator, tissue factor (TF) in freshly recovered endothelial cells (FLECs) of acid‐induced mouse lungs. We gave anesthetized mice intra‐nasal HCl (pH 1.2, 2 ml/kg), or buffer. 2 hours later, we perfused the pulmonary artery with chilled EDTA (5mM, 1ml × 5) to obtain vascular cells, which we labeled with vWf or VE‐cadherin, to detect respectively, FLECs from the extra‐alveolar segment alone, or from all segments. We co‐labeled the cells for TF and subjected them to flow cytometry. Acid increased FLEC TF 91±7% above control in vWf+ cells (n=4, P<0.05), but only 42±7% above control in VE‐cadherin+ cells (n=5, P<0.05). In mice treated with anti‐platelet serum, in which platelet counts fell by 86%, the acid‐induced TF increase in vWf+ cells was inhibited by 63±2% (n=4, P<0.05). We conclude, acid‐induced ALI increases lung endothelial TF expression, which is dominant in extra‐alveolar vessels. Further, the TF expression was platelet‐dependent. We propose lung coagulant mechanisms occur mainly in extra‐alveolar vessels (Support: HL036024).
MODIFIED CELL SIGNALING WITH MULTIVALENT LIGANDS TARGETING INDEPENDENT GPCR'S
Authors: Weber Craig , Brabez Nabila , Vagner Josef , Hruby Victor J , Gillies Robert J , Lynch Ronald
Published: June 2021

Ligands composed of multiple fragments of melanotropin ligand (MSH‐4) exhibit increased apparent binding affinity and signaling relative to the low affinity monomer; binding affinity of trivalent MSH‐4 was >350X higher than the monomer. To maintain the improved binding affinity and signaling while enhancing specificity of targeting, we developed a heterobivalent ligand (HBL) of MSH‐7 linked to cholecystokinin (CCK‐6). In cells with both receptors, the Kd of the HBL was ~5 nM compared to > 250 nM when the MSH receptor was blocked with cold NDP‐MSH (i.e., monovalent CCK binding). At <5 nM HBL, binding to cells with only one receptor was negligible, demonstrating high specificity. Monomeric MSH‐7 elevated cAMP while CCK‐6 increased cell Ca2+. In the presence of both monomeric CCK and MSH, cAMP was elevated, but the Ca2+ response was abolished, indicating feedback inhibition via cAMP. When cells were treated with the HBL, cAMP production was elevated whereas the Ca2+ response to the HBL was attenuated by only 30% relative to monovalent CCK. This level of decrease in Ca2+ response was similar to the effect of the HBL on cells expressing only the CCK receptor. The ability of the HBL to activate signaling is further evidence that the HBL binds to and activates both receptors. Moreover, the high selectivity and binding affinity coupled with altered signaling may be a useful pharmacological property of these new multivalent ligands.
Weight loss and the lean phenotype: Energy expenditure and physical activity during calorie restriction
Authors: MUKHERJEE SROMONA , Lapp Derek , Cosentino Emily , Britton Steven L. , Koch Lauren G. , Novak Colleen M.
Published: June 2021

There are large inter‐individual differences in the ability of people to lose weight on a diet. Because physical activity (PA) plays an important role in obesity resistance, we hypothesized that differences in PA energy expenditure (EE) may account for the individual differences in weight loss on a diet. We used rats selectively bred for high intrinsic aerobic capacity (HCR), which have consistently higher daily PA levels compared to low‐capacity rats (LCRs). We have previously shown that HCRs lose more body weight than do LCRs during calorie restriction (CR). To analyze EE during CR, we re‐exposed a set of male HCR and LCR rats to 21 days of 50% CR; previously, these HCR showed greater weight loss (% baseline) than LCR during CR. Against expectation, repeated CR induced equivalent weight loss in both groups of rats. This may have been due to HCRs’ adjustment to a “feast‐famine cycle.” Nonetheless, we saw significant differences in PA and EE between groups. HCR had greater lean‐mass‐corrected EE than LCR before, but not after, CR, and most of this difference in EE was non‐resting EE (NREE). This paralleled a CR‐induced suppression in daily PA and NREE in HCR, but not LCR; daily activity was still greater in HCR than LCR after 21 days on the diet, however. Altogether, these data support the hypothesis that that the ability to lose weight on a diet varies with NREE. Supported by NIH R01NS055859 to CMN
Similar reductions in expression of proliferative genes are observed in skeletal muscle and organs with age
Authors: Jones Jennifer C , Dilger Anna C
Published: June 2021

Our objective was to observe skeletal muscle expression of 7 genes previously identified in the regulation of organ growth. With age, these genes involved in proliferation were down‐regulated. We hypothesized that these genes would be similarly down‐regulated with muscle growth, but expression would differ between sexes. C57BL/6J female and male mice were sacrificed at 0, 1, 3, 5, and 7 weeks of age. Hind limb muscles from 0 and 1 week old mice, and specific muscles (bicep femoris, gastrocnemius, tibialis anterior, and triceps brachii) from 3, 5, and 7 week old mice were collected along with hearts and livers. Expression of Ezh2, Gpc3, Mdk, Mest, Mycn, Peg3, and Plagl1 was determined by quantitative PCR and normalized to 18s rRNA. At 3 weeks of age, Gpc3, Mest, Peg3, and Plagl1 expression was reduced from newborn expression levels in all tissues (P<0.05 for age). Expression of Ezh2 and Mdk was reduced in heart and muscle at 3 weeks, but not in liver. Few differences in expression were observed between males and females; however, when males and females differed, expression was generally reduced in females. These differences may be related to females reaching mature size sooner than males. Overall, these data suggest that down‐regulation of these proliferative genes with age may coordinate the eventual decreased growth in both muscle and organs. This research was supported by the USDA/NIFA Multi‐State Project NC‐1184.
Acute effects of different continuous positive airway pressures (CPAP) on cardiovascular autonomic control in healthy subjects
Authors: Tobaldini Eleonora , Wu Maddalena A. , Cogliati Chiara B. , Torzillo Daniela , Pecis Marica , Mellace Luca , Morris Kendall F. , Porta Alberto , Montano Nicola
Published: June 2021

CPAP is associated with cardiovascular and respiratory changes and plays a key role in the management of respiratory failure. Scanty data are available on the effects of CPAP on autonomic control in healthy subjects.

The aim of this study was to evaluate the effects of different pressures on cardiorespiratory and autonomic variables in young volunteers.

In 11 subjects we recorded ECG, continuous blood pressure (BP), respiration and end tidal CO2 (etCO2) at baseline (B) and during CPAP application using a face mask. Three different CPAP pressures (4,8 and 12 cmH20) were delivered in random order in each session.

Spectral analysis of heart rate variability (HRV) was used to assess sympathovagal balance: low frequency (LF) and high frequency (HF) oscillations are markers of sympathetic and parasympathetic modulation respectively. Spontaneous baroreflex sensitivity (BRS) was calculated using the spectral alpha index.

CPAP induced a significant decrease in heart rate (HR) and an increase in total power (TP) compared to B. No changes in HR and TP were observed among the different pressures. LF, HF, respiratory frequency and BRS were not affected by CPAP. EtCO2 and BP were unmodified during the experiments.

The data suggest that CPAP acutely modifies HR and TP independently by changes in sympathovagal balance and BRS; direct mechanical effects induced by CPAP might explain these preliminary data. ASI Grant
Cardiovascular Responses to Photothrombotic Middle Cerebral Artery Stroke in Anesthetized Rats
Authors: Adams Sherry , Condrey Jillian Alane , Davenport Paul W.
Published: June 2021

Stroke is the third leading cause of death accounting for greater than 5 million deaths annually world‐wide. A common effect of acute ischemic stroke is elevated blood pressure post‐stroke in which treatment is variable. It is important to allow blood pressure to remain elevated for reperfusion of the ischemic area. A middle cerebral artery (MCA) stroke causes cerebral ischemia which affects the lateral hypothalamus which is a key site for autonomic responses. It is known that the risk of morbidity and mortality due to cardiovascular complications increases following a stroke, little is known about the pattern of arterial blood pressure during the formation of a photochemical thrombotic stroke. The purpose of this study is to determine the cardiovascular changes during a MCA stroke. Rats were implanted with radiotelemetry probes in the abdominal aorta to record heart rate and arterial blood pressure. After a minimum of 7 days recovery from telemetry surgery rats were exposed to MCA photochemical stroke. Recordings were taken during isoflurane anesthesia: 1) pre‐stroke to determine baseline measurements, 2) during photochemical thrombosis and 3) post‐stroke. The brain lesion is induced by injection of a photosensitive dye, Rose Bengal, which is followed with a focal laser irradiation of the MCA to form a photothrombosis. There was a significant decrease in heart rate during the formation of the photothrombosis with no significant change in blood pressure. These results suggest that during photothrombotic formation in the MCA induces a transient change in heart rate with no immediate effect on blood pressure. This suggests that the stroke related increase in blood pressure occurs subsequent to the thrombotic event.
Pharmacological pacemaker current inhibition improves hyperadrenergic postural tachycardia in human subjects
Authors: Schroeder Christoph , Tank Jens , Heusser Karsten , Rieck Daniela , Luft Friedrich C , Jordan Jens
Published: June 2021

Background

Postural tachycardia syndrome (POTS) patients show excessive cardiac sympathetic drive with standing. The pacemaker current I(f) mediates sympathetic influences on heart rate.

Hypothesis

Pharmacological I(f) inhibition with ivabradine improves upright tachycardia in a human pharmacological POTS model.

Methods

In a double‐blind, randomized, three‐way crossover study, 21 healthy men ingested the selective norepinephrine transporter inhibitor reboxetine 8 mg to raise cardiac sympathetic drive and in addition placebo, 7.5 mg ivabradine, or 95 mg metoprolol (positive control) on separate days. We applied 60° head‐up tilt for 20 minutes followed by additional lower body negative pressure.

Results

Resting heart rate was 67±11 bpm with placebo, 65±12 bpm with ivabradine, and 59±7 bpm with metoprolol. During head‐up tilt, heart rate increased 53±17 bpm with placebo. Compared with placebo, ivabradine and metoprolol reduced upright heart rate by 12 (95% CI 4–21, p<.006) and 21 (95% CI 13–30, p<.0001) bpm, respectively. Orthostatic tolerance was not affected by either treatment.

Conclusion

The cardiac hyperadrenergic state induced by pharmacological norepinephrine transporter inhibition is a useful model for human pharmacological research. Using this model, we showed that I(f) inhibition ameliorates hyperadrenergic orthostatic tachycardia. Funded by Deutsche Forschungsgemeinschaft.
The cardiovascular responses to chemoreflex activation are not changed by isolated blockade of NMDA or non‐NMDA receptors in the dorsomedial hypothalamus
Authors: Silva Nathalia Teodoro , Haibara Andrea Siqueira
Published: June 2021

Studies from our laboratory have shown that microinjection of kynurenic acid, a non‐selective antagonist at NMDA and non‐NMDA receptors, into the dorsomedial hypothalamus (DMH) reduced the pressor response and abolished the behavioral response of chemoreflex. This study evaluated the effect of selective blockade of NMDA or non‐NMDA receptors on the cardiovascular responses of the chemoreflex. Bilateral microinjection of AP‐5 into the DMH produced no significant changes on the pressor response (+47 ± 2 mmHg vs 44 ± 3 mmHg) and bradycardia (−245 ± 24 vs −244 ± 27 bpm) of the chemoreflex; however, it was able to reduce the cardiovascular responses induced by NMDA (+21 ± 1 vs 8 ± 2 mmHg; +135 ± 13 vs 69 ± 18 bpm). Bilateral microinjection of CNQX into the DMH also produced no changes on the pressor response (+44 ± 9 vs +36 ± 8 mmHg) and bradycardia (−228 ± 34 vs −219 ± 32 bpm) of the chemoreflex, but significantly reduced the cardiovascular responses induced by AMPA (+21 ± 2 vs +5 ± 2 mmHg; +111 ± 5 vs +40 ± 17 bpm). These results indicate that isolated blockade of NMDA receptors or non‐NMDA receptors of the DMH does not promote changes in cardiovascular responses to chemoreflex. Support: CNPq/FAPEMIG.
Changes in peripheral but not central pulse wave velocity with estradiol administration is positively correlated with muscle sympathetic nerve activity
Authors: Miner Jennifer Ann , Miner Jonathon Cory , Kaplan Paul F , Minson Christopher T
Published: June 2021

To investigate how estrogen affects autonomic and cardiovascular function, we measured muscle sympathetic nerve activity (MSNA), and central and peripheral pulse wave velocities (PWV) in 8 young healthy women after 3 days of endogenous sex hormone suppression (via gonadotropin‐releasing hormone antagonism). Five subjects continued hormone suppression for 2 days, combined with 0.2mg/day transdermal estradiol, and were retested. Estradiol administration decreased peripheral PWV (p<0.05), a finding that does not exist during normal menstrual fluctuations. There was no change in central PWV (p=0.27). In addition, we used linear regression analyses to explore the relationship between MSNA and PWV. Across all subjects and conditions, peripheral (brachial‐ankle) PWV was positively correlated with MSNA bursts/min (R2=0.33, p=0.05) and bursts/100 heartbeats (R2=0.39, p=0.03), whereas no relationships existed between central (carotid‐femoral) PWV and MSNA parameters (bursts/min, R2<0.01, p=0.90; and bursts/100 heartbeats, R2<0.01, p=0.77). These data suggest sympathetic outflow to the peripheral arteries may explain the changes in peripheral PWV with estrogen administration. Degree of sympathetic innervation in the specific arteries studied may explain the differences between peripheral and central PWV measurements.

Supported by NIH Grant HL081671.
Spontaneous baroreflex control of muscle sympathetic nerve activity: Impact of baseline duration
Authors: Holwerda Seth W. , Vianna Lauro C. , Fadel Paul J.
Published: June 2021

The relationship between spontaneously occurring changes in muscle sympathetic nerve activity (MSNA) and diastolic blood pressure (DBP) is increasingly being used to estimate baroreflex MSNA sensitivity. Although spontaneous measures have been shown to correlate with MSNA baroreflex sensitivity derived using the modified Oxford, standardized analyses procedures have not been established. For example, studies have used varying durations of baseline for this analysis and whether spontaneous baroreflex measures are affected by the period of data used (e.g., 5 vs. 2min) is unknown. Also, how bin size impacts the reliability of different durations is unknown. To begin to address this, in 8 subjects, weighted linear regression analysis between MSNA and DBP was used to determine baroreflex MSNA sensitivity. Intraclass correlation coefficients (ICC) for each bin size (1, 2, and 3 mmHg) were calculated to examine reliability of spontaneous MSNA sensitivity over segment durations of 2‐, 5‐, and 10‐minutes. Overall ICC for burst incidence was high (0.884; P<0.05) indicating an acceptable reliability. Importantly, the reliability over different segment durations was unaffected by bin size (e.g., 3 mmHg bins: ICC=0.875, P<0.05). Similar results were found for burst strength. These preliminary findings suggest that the duration of baseline and bin size does not affect spontaneous MSNA baroreflex estimates at rest.
Dietary palmitate and palmitate accumulation in the steatotic rat liver confounds fructose‐induced endoplasmic reticulum (ER) stress
Authors: patel chirag r , Douard Veronique , Siegel Miles , Ferraris Ronaldo
Published: June 2021

Consumption of high fructose (HF) results in marked hepatic lipogenesis and steatosis. We recently found dramatic and specific increases in levels of palmitate (P), oleate (O) and other fatty acids in the liver of rats fed HF. P is known to damage hepatocytes via oxidative and ER stress, and to cause dysregulated lipogenesis, conditions that lead to hepatic steatosis. We investigated the contributions of (1) ER stress in F‐induced steatosis, and (2) P in aggravating the adverse effects of F in rats fed isocaloric diets for 3 mo: (glucose (G) + P, G + O, F + P, F + O). Sugars were 40% (w/w), lipids 10%. Dietary F but not G increased fat accumulation in the liver, and dietary P markedly exacerbated this effect. Protein expression of the ER stress and unfolded protein (UPR) response biomarkers binding immunoglobulin protein (BiP) and spliced X‐box binding protein‐1 (XBP‐1s) in whole cell lysate was higher in the liver of rats fed P, independent of dietary sugar. By Western blot, F increased expression of XBP‐1s in nuclear fractions, independent of dietary lipid. By immunocytochemistry, the liver of F‐fed rats had a greater number of nuclei with XBP‐1s. Thus, F induces the inositol‐requiring enzyme 1 (IRE1) pathway of the UPR to ER stress already known to enhance hepatic lipogenesis. P either from the diet or from excessive F intake may aggravate hepatic steatosis. NSF 10S‐1121049
Proteomic Analyses on Mitochondria in Rats model of Heart failure
Authors: Liu Tingting , Chen Le , Kim Eunjung , Knowlton Anne
Published: June 2021

Mitochondrial dysfunction contributes significantly to the decline in cardiac function in heart failure. We hypothesized that there would be abnormalities in mitochondrial structure and proteome with the progression of heart failure.

Methods

We used our established high LAD ligation to generate ischemic heart failure in 3 month old male rats. Rats were studied at 9 weeks post ligation.

Results

Echo confirmed the presence of heart failure post ligation. Electron microscopy of left ventricle (LV) samples showed many mitochondrial changes including decreased size, increased number, abnormal distribution, and cristae loss. Mitochondrial functional studies showed that total ATP was decreased and mitochondrial respiration impaired in heart failure. Analysis of LV mitochondrial protein by 2D gel and mass spec identified 27 differentially expressed proteins, with 12 up‐regulated and 15 down‐regulated proteins in the failing heart. Ongoing work is investigating additional target proteins and their regulation. Supported by HL077281.
Ganglionic blockade does not impair the chronic CNS‐mediated antidiabetic action of leptin in streptozotocin‐induced diabetic rats
Authors: da Silva Alexandre A. , do Carmo Jussara M. , Dubinion John H. , Hall John E.
Published: June 2021

This study examined the role of adrenergic and non‐adrenergic factors released by sympathetic fibers in the CNS‐mediated chronic antidiabetic effects of leptin. Male Sprague‐Dawley rats were instrumented with telemetry probes and arterial and venous catheters for determination of blood pressure (BP), heart rate (HR), blood sampling and intravenous (IV) infusions. An intracerebroventricular (ICV) cannula was placed into the brain lateral ventricle for infusion of leptin or vehicle. After control measurements, STZ was injected IV (50 mg/kg) to induce diabetes and 5 days later leptin (15 μg/d, n=5) or saline vehicle (n=4) were infused ICV for 12 days via osmotic pumps. Beginning on day 6 of treatment, the ganglionic blocker hexamethonium (15 mg/kg/hr) was infused IV for 6 days. Induction of diabetes was associated with hyperglycemia (350±19 mg/dL), hyperphagia (43±3 g/d), bradycardia (−70±11 bpm), polyuria and increased water consumption, which were fully reversed by ICV leptin infusion. Although hexamethonium markedly attenuated leptin's effect on HR, it failed to impair leptin's ability to restore euglycemia (66±2 mg/dL) or to prevent the hyperphagia, polyuria or increased water intake in STZ‐diabetic rats. These results suggest that leptin's powerful CNS antidiabetic actions are mediated via non‐autonomic mechanisms. (NHLBI‐PO1 HL51971, AHA)
Peptide Quantum Dot Conjugates Detect Integrin αvβ3
Authors: Orndorff Rebecca L. , Hong Nan Kang , Yu Kevin , Debolt Kristine , Muzykantov Vladimir R. , Huang Shaohui , Fisher Aron B. , Chatterjee Shampa
Published: June 2021

Quantum dots (QD) are fluorescent semiconductor nanocrystals composed of a CdSe/ZnS core/shell structure. QD have multiplexing capabilities and unique photophysical properties including broad excitation spectra, narrow Gaussian‐shaped emission spectra, enhanced photostability, and near 100% quantum yield, as compared to their fluorophore complements. Functionalization of the QD surface with peptide ligands is an effective method for labeling endogenous proteins in cells and tissues. Development and characterization of QD probes for targeting the pulmonary endothelium could provide a methodology for enhancing in vivo microscopy. Integrin αvβ3 is expressed by vascular endothelial cells, and is a receptor for extracellular matrix proteins, such as vitronectin and fibronectin, with an exposed arginine‐glycine‐aspartic acid (RGD) tripeptide sequence. Prior studies have demonstrated the use of RGD peptide QD conjugates (RGD‐qds) to target integrin αvβ3 in tumor vasculature. In this study, we monitored the labeling of endothelial cells by RGD‐qds under conditions where integrin αvβ3 expression is increased in vitro, by angiotensin II (AngII) exposure of vascular endothelial cells and in mouse lungs in vivo by lipopolysaccharide (LPS) administration. Fluorescence microscopic evaluation showed RGD‐qds to be bound on the treated cells, but not on untreated controls. Western blot analysis supported an increase in integrin αvβ3 expression in endothelial cells exposed to AngII. These results illustrate the use of QD probes for intravital multiphoton microscopic studies of stimulated and naïve pulmonary endothelium.
Enhanced tetrahydrobiopterin contributes to sodium restriction‐induced improvements in large elastic artery compliance in older adults with elevated systolic blood pressure
Authors: Racine Matthew Lee , Geolfos Candace J , DeVan Allison E , Gates Phillip E , Chonchol Michel , Seals Douglas R , Jablonski Kristen L
Published: June 2021

Dietary sodium restriction (DSR) improves carotid artery compliance (CC) in middle‐aged and older adults (MA/O) with moderately elevated systolic blood pressure (SBP), but the mechanisms of action are unknown. Reduced tetrahydrobiopterin (BH4) bioactivity contributes to age‐associated vascular dysfunction. We hypothesized that increased BH4 bioavailability may contribute to improvements in CC with DSR. SBP was reduced following 4 weeks of a low sodium (LS; 56±11 mmol/day; 125±2 mmHg) vs. normal sodium (NS; 160±7 mmol/day; 141±4 mmHg) diet (p<0.001; randomized, cross‐over design; 5M/4F; 61±3 yrs). Baseline CC was 43% greater during the LS vs. NS condition (0.14±0.02 vs. 0.097±0.02 mm/mmHg, p=0.05). Acute oral BH4 administration (10 mg/kg) improved CC vs. placebo during the NS condition (0.13±0.02 mm/mmHg, p<0.05) to levels not significantly different than the LS placebo state, but had no effect on CC during the LS condition (0.14±0.02 mm/mmHg). BH4 had no significant influence on SBP in either condition (LS, 127±3 mmHg, p=0.30; NS, 138±3 mmHg; p=0.13). Results were similar when presented as the β‐stiffness index, a more BP‐independent expression of carotid artery distensibility. These findings are consistent with the hypothesis that DSR improves CC in MA/O with moderately elevated SBP in part by enhancing BH4 bioavailability.

NIH AG013038, AG006537, AG03114, AG033994, RR025780
Correlation between HbNO and NOx in septic shocked rats
Authors: Rosales-Hernandez Tania Fabiola , Mendieta-Wejebe Jessica Elena , Rosales-Hernandez Martha Cecilia , Kross Robert David , Villanueva Cleva
Published: June 2021

Male Wistar rats were subjected to septic shock by means of intravenous administration of lipopolysaccharide (LPS, 8 mg/kg). Blood samples were taken from the left carotid artery initially and 1.5 and 6 hours after LPS infusion. The blood samples were treated with heparin and centrifuged. The HbNO adduct was measured in the red cell fraction through electron paramagnetic resonance, while reduced nitrates (NOx) were measured in plasma (Griess method, Cayman Chem Co. kit). No HbNO was detected in the basal samples. When compared to the 1.5 h HbNO levels those at 6 hours significantly increased after LPS administration. The basal levels of NOx did not change after 1.5 h but significantly increased 6 h after LPS administration. A significant correlation between HbNO and NOx was only observed 6 hours after LPS administration. Since NO needs deoxyhemoglobin to form the HbNO adduct, it is concluded that a correlation between HbNO and NOx levels could be an indicator of hypoxia in septic shock. This study was supported by grants SIP20110949 and CONACYT083090
Proteolytically‐derived inflammatory peptides from the bowel may circulate systemically in shock
Authors: Kistler Erik B , Alsaigh Tom , Chang Marisol , Richter Michael , Schmid-Schonbein Geert W
Published: June 2021

Small bowel malperfusion and increased permeability may be key pathologic events in shock, allowing gut‐derived inflammatory peptides systemic access. Proteolytically formed as part of normal digestion, the peptides do not normally cross the mucosal barrier but may do so in shock. To test this idea, rats were subjected to hemorrhagic shock (35 mmHg for 100 min) with laparotomy, and saline or the protease inhibitor nafamostat mesilate was injected into the small bowel. Control animals were subjected to laparotomy without shock. Fluorescently labeled casein was injected into the small bowel to determine the ability of proteolytically generated peptides to reach the systemic circulation. Permeability significantly increased after ischemia in all shock groups compared to controls as assessed by casein fluorescence in the mesenteric microcirculation and in plasma (p<0.01). Nafamostat mesilate decreased permeability in the microcirculation and systemically (p<0.01). These results demonstrate that in an experimental model of hemorrhagic shock, bowel permeability is significantly increased to proteolytically derived peptides, and is mitigated by enteral protease inhibition. Inflammatory peptides from the bowel may reach the systemic circulation and contribute to the pathophysiology of gut‐derived circulatory shock. Supported by GM85072, and the ASCCA/FAER/Hospira Physician Scientist Award.
Vascular hyperpolarization contributes to onset and steady‐state exercise hyperemia in humans
Authors: Crecelius Anne R. , Kirby Brett S. , Richards Jennifer C. , Garcia Leora J. , Luckasen Gary J. , Larson Dennis G. , Dinenno Frank A.
Published: June 2021

We tested the hypothesis that vascular hyperpolarization contributes to both the onset and steady‐state hyperemic response to exercise. In Protocol 1 (n=11), forearm blood flow (FBF; Doppler ultrasound) was measured during rhythmic handgrip exercise at 10% maximal voluntary contraction for 5 minutes under control (intra‐arterial saline; T1) conditions, after combined inhibition of Na+/K+ATPase and KIR channels [via ouabain and barium chloride (BaCl2), respectively; T2] alone and in the presence of combined nitric oxide synthase (L‐NMMA) and cyclooxygenase inhibition (ketorolac; T3). Drugs were not infused during exercise due to potential influences on basal vascular tone. The total hyperemic responses were significantly (P<0.05) attenuated from control at 30 seconds (50 ± 4 and 65 ± 2%), 1 minute (34 ± 4 and 41 ± 3%), and 2 minutes (20 ± 4 and 23 ± 4%; T2 and T3 respectively) of exercise. FBF was not different in the last 2 minutes of exercise. In Protocol 2 (n=6), all study drugs were infused prior to and during exercise to assess the impact on steady‐state hyperemia. Steady‐state FBF was significantly reduced during T2 vs T1 (123 ± 18 vs 156 ± 21 ml/min; −21 ± 4%), and further reduced during T3 (108 ± 17 ml/min; −32 ± 3%). Our data indicate vascular hyperpolarization as a novel contributing vasodilatory pathway in the complex blood flow response to exercise at the onset and during steady‐state hyperemia.

Supported by HL102720
Back Pain in School Children Associated with Backpack Use
Authors: Anderson Kevin Edward
Published: June 2021

The aim of this study is to determine if backpack use in school children is associated with back pain. Back pain questionnaires examined the prevalence of back pain in 108, 8–14 year old schoolchildren in San Diego County area with IRB approved consent forms completed and signed by both parents and students. The completed questionnaires were entered into a Microsoft Excel spreadsheet. A chi‐square test for independence was used for the analyses of data using online computer software. Of the 108 students assessed, 88 students wore backpacks and 20 students used roller bags to carry their books and other supplies. Of these 88 students, 54 experienced back pain while 34 students did not. Of the 20 students who used roller bags, 2 experienced back pain while 18 students did not. Thus, wearing a backpack is associated with back pain (P < 0.05). Of the students who carried backpacks and experienced back pain, 80% carried more than 1 textbook on average. Of the students who wore backpacks and did not experience back pain, only 14% carried more than 1 textbook on average. Thus, carrying more than one textbook on average was associated with back pain (P < 0.05) in students who carried backpacks. Students who carry backpacks as opposed to roller bags are more likely to experience back pain. In addition, students who carry backpacks with more than one textbook on average are more likely to experience back pain. It is recommended that students reduce the number of textbooks carried in their backpacks or use roller bags.
Inactivity‐induced phrenic motor facilitation is associated with decreased phrenic burst‐to‐burst variability
Authors: Borchert Corie , Strey Kristi A , Baertsch Nathan , Baker-Herman Tracy L
Published: June 2021

Reduced respiratory neural activity in ventilated rats elicits rebound increases in phrenic discharge once neural activity has been restored, a form of plasticity called inactivity‐induced phrenic motor facilitation (iPMF). We hypothesized that iPMF is associated with reduced phrenic burst‐to‐burst variability. Phrenic discharge was measured in anesthetized, vagotomized and ventilated Harlan (H) and Charles River (CR) Sprague Dawley rats exposed to a 30 min neural apnea or an equal duration of baseline conditions (time control). As expected, H rats expressed iPMF at 5 and 60 (p<0.05) min post‐apnea, whereas CR rats expressed iPMF only at 5 (p<0.05), but not 60 (p>0.05) min. Inspiratory time (Ti), expiratory time (Te) and peak area variability was assessed using Poincare plot analyses for burst n vs burst n+1 before, and 5 and 60 min post‐apnea. In H rats exposed to a neural apnea, standard deviations of the Poincare plot (SD1, SD2) for Ti and Te were significantly decreased at 5 and 60 min post‐apnea (p< 0.01). In CR rats exposed to a neural apnea, decreases in SD1 and SD2 for Ti and Te were observed at 5 (p<0.01), but not 60 (p>0.05) min post‐apnea. No changes in SD1 or SD2 for Ti or Te were observed in time controls (p>0.05), and no changes in SD1 or SD2 for peak area were observed in any group (p>0.05). These data suggest that iPMF is associated with decreased variability in Ti and Te. NIH HL105511 and UW‐Madison Regent Scholars Fund
A Molecular Mechanism For Suppression Of Colonic Inflammation By Gut Bacteria
Authors: Gurav Ashish , Singh Nagendra , Ganapathy Vadivel
Published: June 2021

Ulcerative colitis is associated with colonic inflammation and increases colon cancer risk. Short‐chain fatty acids (SCFAs; acetate, propionate, and butyrate) are produced in colon by bacterial fermentation of dietary fibers, which protect against inflammation and cancer in colon. Our aim was to determine the role of these bacterial metabolites in colonic inflammation and colon cancer at molecular level. Dendritic cells (DCs) in colon extend their cellular processes across epithelial tight junctions to sample the luminal contents for immunogens, consequently initiating appropriate T and B cell mediated immune response. We hypothesized that SCFAs induce tolerogenic immune response in colon. Our studies show that DCs, when exposed to butyrate and propionate, but not to acetate, upregulate indoleamine 2,3‐dioxygenase (IDO) and that the ability of these two SCFAs to inhibit HDACs is responsible for this action. This process is dependent on Slc5a8, a transporter for SCFAs. Pharmacological inhibition of IDO in mice subjected to azoxymethane/dextran sulfate‐mediated colorectal carcinoma enhances colon cancer incidence. We conclude that propionate and butyrate protect against colonic inflammation and colon cancer partly through DC‐mediated immunosuppression and that the mechanism involves Slc5a8‐mediated entry of these SCFAs into cells with subsequent inhibition of HDACs.
RESTORATION OF RETINAL GANGLION CELL DENDRITIC ARBORS AFTER AXONAL INJURY IN VIVO.
Authors: Di Polo Adriana
Published: June 2021

Purpose

Dendrites are major determinants of how retinal neurons integrate and process incoming information. We showed that retinal ganglion cells (RGCs) undergo shrinkage of dendritic arbors soon after axotomy, but the molecular mechanisms that underlie injury‐induced dendritic remodeling are poorly understood. Here, we investigated the role of the mTOR (mammalian target of rapamycin) pathway in RGC dendritic structure and synaptic input after acute optic nerve lesion.

Methods

Adult transgenic mice carrying the yellow fluorescent protein (YFP) gene were subjected to optic nerve axotomy. Retinal mTOR activity was manipulated by intraocular injection of siRNA against the mTOR repressor REDD2 or by intraperitoneal administration of the mTOR inhibitor rapamycin. Retinal whole‐mounts were prepared and RGC dendritic trees were 3‐D reconstructed.

Results

Optic nerve axotomy leads to marked downregulation of mTOR activity in RGCs correlating with dendritic shrinkage prior to RGC death onset. siREDD2 stimulated mTOR activity in injured RGCs leading to increased dendritic length, surface and complexity compared to control retinas. Importantly, increased mTOR activity in RGCs restored glutamatergic bipolar cell inputs onto RGC dendritic shafts.

Conclusion

We report a novel role for the mTOR pathway in the restoration of RGC dendritic arbors and excitatory synaptic input after acute optic nerve lesion.
Higher order assemblies in the GET membrane protein targeting pathway
Authors: Clemons William , Chartron Justin , Suloway Christian
Published: June 2021

Tail‐anchor (TA) proteins represent an important and diverse class of membrane proteins that are unable to be targeted via the co‐translational SRP pathway. Instead, recent discoveries have identified factors directly involved in targeting these proteins to the ER. In yeast, these proteins form the GET pathway. Our lab has focused on structural and mechanistic studies of these proteins. The pathway as we posit begins with cytoplasmic chaperones that deliver the TA‐proteins to Sgt2, which routes the proteins to Get3 via a Get4/Get5 hetero‐tetramer. Get3 then forms a stable complex with the TA and delivers the proteins to the ER membrane. We have begun characterizing these complexes using structural biology and biochemistry. I will frame a discussion of the pathway from our unique structural perspective presenting new results on parts of the pathway.
Using H218O to study protein and lipid flux: Is dyslipidemia a problem of triglyceride and/or apoB production?
Authors: Previs Stephen , McLaren David , Castro-Perez Jose , Shah Vinit , Herath Kithsiri , Stout Steven , Miller Paul , Zhou Haihong , Li Wenyu , Wang Sheng-Ping , Mendoza Vivienne , Johns Douglas , Murphy Beth , Cumiskey Anne-Marie , Wilsie Larissa , Imbriglio Jason , Pinto Shirly , Hubbard Brian , Roddy Thomas
Published: June 2021

Investigations surrounding dyslipidemia often examine lipid (e.g. triglyceride) and protein (e.g. apoB) kinetics in separate studies which is unfortunate since the pathways are related. We recently demonstrated the ability to quantify protein flux in vivo using H2 18O; the hydrolysis of pre‐existing proteins in H2 18O generates labeled amino acids, thus protein synthesis is estimated from the incorporation of those labeled amino acids into newly made proteins. We now demonstrate a similar logic for studying lipid synthesis, i.e. the degradation of pre‐existing lipids in H2 18O labels fatty acids, thus lipid synthesis is estimated from the incorporation of 18O‐fatty acids into different end‐products using LC‐MS/MS. Although the chromatographic runs are complex (numerous analytes co‐elute) it is possible to measure the labeling of specific lipids. We demonstrate the application of this method in studies of triglyceride and apoB production; it seems possible to uncouple triglyceride and apoB flux in C57Bl/6J mice under different conditions, e.g. control vs Intralipid or MTPi‐treated. The method described herein is suitable for routine investigations in rodents, the tracer is given via intraperitoneal injection and the analyses require 1 to 2 plasma samples (each ≤40 μL). Our approach should enable “high‐throughput” in vivo studies regarding the pathophysiology of dyslipidemia.