bluuebunny/crossref_metadata_2025 huggingface dataset:
Length‐tension relationship of human thoracic ducts
Authors: Telinius Niklas , Drewsen Nanna , Kold‐Petersen Henrik , Pilegaard Hans , de Leval Marc , Aalkjaer Christian , Hjortdal Vibeke , Briggs Boedtkjer Donna
Published: June 2021

Introduction

Active force produced in vessels is directly related to smooth muscle length. Length‐tension relationship is important for characterization of vessels in vitro. We here present a length‐tension curve of isolated human thoracic ducts.

Materials and methods

Thoracic ducts were harvested from 10 patients undergoing esophageal cancer surgery at the department of thoracic and cardiovascular surgery, University Hospital in Aarhus. The vessels were freed from any surrounding tissue and cut into 2 mm long segments and mounted in a wire myograph for isometric recordings.

We used a 10 μM noradrenaline in a K‐PSS (123mM K) solution as an activator to produce maximum force.

Results

Length‐tension relationship was determined from non linear regression fits. Fig 1 shows length‐tension relationship from 45 vessel segments from 10 vessels (n=10). The vessels produced an average total and passive tension of 10.79 and 3.19 N/m, equaling a pressure of 65 ± 7 and 20.8 ± 3 mmHg according to Laplace's law.

Conclusion

We have shown it is possible to harvest the thoracic duct from humans and perform in vitro experiments. By using a passive normalization procedure we can now quickly determine the diameter which produces maximal active tension. The results are fundamental for our further physiological and pharmacological studies of these vessels.

This research was funded by the Danish Research Council
NADPH Plays a Critical Role in Modulating Endothelial Dysfunction in the Post‐Ischemic Heart.
Authors: Reyes Levy A , Dumitrescu Cristian , Druhan Lawrence J , Talukder M. A. Hassan , Zweier Jay L
Published: June 2021

Reperfusion injury has been shown to cause dysfunction in vascular endothelium. The current understanding of this relationship is incomplete, but is critical in developing new treatments of post‐ischemic myocardium. Previously we demonstrated that endothelial dysfunction does not involve a loss of endothelial nitric oxide synthase (eNOS), but rather is triggered by loss of cofactors/substrates of the enzyme. Recently we showed the eNOS cofactor, BH4, to be depleted in the ischemic heart, and restoration of lost BH4 in isolated heart preparations partially rescued coronary flow. Our current work extends these studies to NADPH, an eNOS substrate. We have found that NADPH declines to ~30% of normal levels at 30 minutes post‐ischemia. The importance of this decline in the eNOS substrate was shown in isolated hearts, where repletion of lost NADPH 30 minutes post ischemia resulted in a dramatic improvement in coronary flow, increasing 77 ± 4% of control. It remains to be determined why the decrease in NADPH occurs, and if this loss can be prevented during ischemia/reperfusion injury. In spite of these questions repletion of eNOS cofactors/substrates may be an efficacious therapy for improving endothelial dysfunction in the post‐ischemic heart.
Vitamin E Deficiency in Children with Long‐chain 3‐hydroxyacylCoA dehydrogenase deficiency (LCHADD)
Authors: Gillingham Melanie B , Harding Cary O , Leonard Scott W , Traber Maret G
Published: June 2021

Background

Recommended treatment for LCHADD, an inherited defect in mitochondrial fatty acid oxidation, is based on fasting avoidance and following a very low fat diet (<10% of energy from long‐chain fat). A chronic complication of this disease is areflexia with progressive peripheral neuropathy similar to that observed in patients with vitamin E deficiency associated neuropathy.

Objective

We hypothesized children with LCHADD have an iatrogenic vitamin E deficiency that is associated with peripheral neuropathy.

Methods

Neurological exam and plasma Vitamin E concentrations were measured in 5 subjects with LCHADD and 2 controls.

Results

All 5 subjects with LCHADD had areflexia. One subject had severe peripheral neuropathy with loss of mobility. Four of five subjects were vitamin E deficient as defined by plasma α‐tocopherol concentrations < 20 μM. Controls had normal neurological exam and plasma vitamin E concentrations.

Conclusions

Vitamin E deficiency was observed in subjects with LCHADD who had areflexia. Further study is needed to determine if vitamin E supplementation will improve neurological function.

Supported by the Am. Diabetes Association 1‐06‐JF‐19, PHS Grant UL1 RR024140 & K01 DK071869.
Stunting and wasting rates in diverse settings in developing countries
Authors: Krebs Nancy F. , Mazariegos Manolo , Chomba Elwyn , Tshefu Antoinette , Pasha Omrana , Goco Norman , Das Abhik , Kindem Mark , Wright Linda L , Hambidge Michael
Published: June 2021

Stunting, which often develops during the first 2 yr of life, is very difficult to reverse. The Global Network for Women's and Children's Health Research obtained pilot data on growth and feeding practices prior to undertaking a multi‐country (Guatemala, Pakistan, Democratic Republic of Congo, and Zambia) intervention trial of complementary feeding.

METHODS

Each country identified 10‐18 clusters, and from each a convenience sample of 20‐40 children aged 12‐24 months was enrolled. After standardized training, anthropometric measures were obtained and a feeding practice questionnaire was administered to mothers of the participants. Growth data were compared to the WHO Multicentre Growth Reference; stunting was defined as length‐for‐age (LAZ) < ‐2 SD; wasting as weight‐for‐length (WLZ) < ‐2 SD.

RESULTS

A total of 1,758 children were included; mean (SD) age was 17.2 (3.5) mo; 74% of children were still breastfed. Mean (SD) anthropometric data for each site (n):

Stunting rates are strikingly high in these settings, while wasting is much less prevalent. Intervention studies to improve the quality of complementary feeding are warranted. Support: NIH/NICHD, Bill & Melinda Gates Fdn, NIH/ODS
Characterizing the Response of Skeletal Muscle Microvasculature to Imposed Oxygen Variations
Authors: Dias Gemma Marie , Milkovich Stephanie , Goldman Daniel , Ellis Christopher G
Published: June 2021

Computational modeling of the oxygen regulatory system has shown how signals conducted upstream from capillaries change the flow pattern in the arteriole tree. The simulation showed that the hemodynamic response to higher frequency oscillations (period 30 sec) is attenuated relative to lower frequency oscillations (period 90 sec). To test this prediction in vivo, a custom O2 gas chamber is used to supply O2 at the surface of exposed skeletal muscle and a sequence of 3 oscillations (1st and 3rd 30 sec period, 2nd 90 sec period, see figure) were generated. The hemodynamic response in capillaries to this stimulus was quantified using intravital video microscopy and a functional image analysis system (RBC velocity and hematocrit to yield RBC supply rate, SR). The RBC supply rate response supported the results from the computational model for the 1st and 2nd sine oscillation. The SR response to the higher frequency oscillation was attenuated to ~60‐70% of the lower frequency stimulus. However, the 3rd sinusoidal oscillation showed no response to the O2 signal suggesting that other factors need to be included in the model. Overall, the model and experimental results support the hypothesis that regulation of O2 supply involves a conducted signal along the arteriolar tree controlling both flow resistance and distribution of RBCs at bifurcations. (NIH R33 HL089094).
Influence of gender on muscle strength, power and body composition in healthy subjects and mobility‐limited older adults
Authors: Reid Kieran F , Doros Gheorghe , Cloutier Gregory , Clark David , Carabello Robert , Phillips Edward , Fielding Roger
Published: June 2021

Objective

To explore the gender differences in lower‐limb strength, power and body composition in a cross‐sectional study on 31 healthy middle‐aged adults (47.2 ± 5 yrs, 14 males), 28 healthy older adults (74 ± 4 yrs, 16 males), and 34 older adults with mobility impairments (77.8 ± 5 yrs, 16 males).

Methods

One repetition maximum (1RM) strength and peak power were estimated using the bilateral leg press. Computed tomography was used to assess mid‐thigh body composition.

Results

Males demonstrated higher values for muscle strength, power, muscle cross sectional area, and intermuscular adipose tissue across all groups (p < 0.05) (table). Female gender was associated with greater deposits of subfascial and subcutaneous adipose tissue across all groups (p < 0.0001).

Conclusion

Gender exerted a consistent influence on the differences in lower‐limb muscle performance and body composition among healthy middle‐aged, healthy older, and mobility‐limited elders. Hormonal factors may explain the divergent gender‐specific differences in muscle size and adipose tissue accumulation.

*Significant overall gender effect (p < 0.05)

NIA AG‐18844 and the USDA 58‐1950‐7‐707
Intermittent hypoxia increases blood pressure in old female rats
Authors: Hinojosa‐Laborde Carmen , Mehring Cindy , Tang Kejian , Fortepiani Lourdes , Cunningham Tom , Mifflin Steve
Published: June 2021

Blood pressure (BP) in male rats exposed to intermittent hypoxia (IH) increases (5.4 ± 1.0 mm Hg), but not in females (1.6 ± 1.0 mm Hg). Female sex hormones appear to protect against the BP increase because ovariectomized females respond to IH with an increase in BP (5.1 ± 1.0 mm Hg) similar to males. This study tested the hypothesis that old female rats with low plasma estradiol would also respond with BP increases during IH. BP was measured by radiotelemetry in 24 month old female rats (n=5). The phases of the experiment were control, IH, and recovery (7days/phase). During IH the rats were exposed to 8 hours of IH while sleeping (8am‐4pm) when oxygen levels cycled between 21% (90 sec) and 10% (90 sec). Animals were not exposed to IH during the control and recovery phases. BP during the control and IH phases were compared, and the increase in BP during IH was 4.7 ± 0.6 mm Hg. The BP response to IH was significantly greater in 24 month old females compared to young females (p<0.05). The elevated BP in old females was sustained throughout the 24 hours, and returned to control levels during the recovery phase. Plasma estradiol levels were low, 3.4±1.0 pg/ml, compared to young rats (52±8 pg/ml). This study provides more evidence that female sex hormones protect against the BP increase during IH. These results also predict that the hypertension associated with sleep apnea is more prevalent in postmenopausal compared to premenopausal women.
Effects of chronic chromium picolinate treatment on glycemic control and kidney function of db/db mice
Authors: Mozaffari Mahmood , Wimborne Hereward , Liu Jun , Abdelsayed Rafik , Rodriguez Nancy
Published: June 2021

Previous studies suggest a clastogenic effect of chromium picolinate (Cr(Pic)3). We tested the hypothesis that Cr(Pic)3 improves glycemic status accompanied by decreased renal accumulation and excretion of 8‐hydroxy deoxyguanosine (8‐OHdG). Male db/db mice were fed diets lacking or containing 5 or 100 mg/kg chromium (as Cr(Pic)3) from 6‐24 weeks of age; lean nondiabetic db/m mice served as controls. The untreated db/db mice displayed marked elevation in hemoglobin A1c than db/m controls. The db/db mice fed the 100 (but not 5) mg/kg diet displayed lower hemoglobin A1c (p<0.05). As expected, total proteinuria and albumin excretion were significantly greater in db/db than db/m mice; Cr(Pic)3 reduced total protein and albumin excretions in db/db mice. Urinary excretion of 8‐OHdG was also significantly higher in the untreated db/db than db/m mice and dietary Cr(pic)3 treatment reduced urinary 8‐OHdG excretion. Renal tubular cells of the db/db kidney showed moderate‐intense immunoreactivity for 8‐OHdG in the form of cytoplasmic microgranules. Interestingly, renal tissue of the Cr(Pic)3‐treated db/db mice showed a decrease in the intensity of staining for 8‐OHdG than those of untreated db/db mice. Taken together, the data suggest that while Cr(Pic)3 does not increase the propensity for oxidative DNA damage, it exerts dose‐dependent effects on glycemic control and kidney function in db/db mice. Supported by NIH.
C‐peptide confers protection in renal cortical endothelial cells during Type I diabetes by preventing the phosphorylation of glucose‐6‐phosphate dehydrogenase
Authors: Vejandla Himani L. , Kothur Anand , Dabkowski Erinne R. , Hollander John M. , Frisbee Jefferson C. , Brock Robert W.
Published: June 2021

Previously we have shown that C‐peptide, a by‐product of insulin biosynthesis, improves renal peritubular capillary blood flow and reduces vascular oxidants. NADPH appears to be critical to this effect via the actions of numerous vasoprotective systems. We have found that diabetes results in a significant reduction in endothelial NADPH, that is subsequently restored with C‐peptide. We hypothesize that C‐peptide provides protection to renal cortical endothelial cells (RCEs) during type I diabetes by restoring the activity of glucose‐6‐phosphate dehydrogenase (G6PD), the principal source of NADPH synthesis. Our data show that RCEs from diabetic mice have diminished G6PD activity (p<0.05) and their treatment with C‐peptide restores its activity back to non‐diabetic levels (p<0.05). These changes in G6PD activity occurred with concomitant alterations in NADPH. Using 2‐D gel electrophoresis of RCE lysate coupled with immunoblotting for G6PD, we demonstrate that diabetic RCEs have a significant increase in G6PD phosphorylation. C‐peptide treatment reduced the magnitude of this phosphorylation in diabetic RCEs, which occurred concomitant to restored G6PD activity. These results suggest that improving the activity of endothelial G6PD, by preventing its phosphorylation, may be a potential mechanism by which C‐peptide confers protection to RCEs during type I diabetes. NIH R01 DK067582
Inhibition of enterocyte NFκB exacerbates intestinal barrier dysfunction in a murine model of sepsis
Authors: Clark Jessica A. , Samocha Alexandr J. , Coopersmith Craig M.
Published: June 2021

Inhibition of enterocyte NFκB augments sepsis‐induced gut apoptosis and increases mortality. It is unknown if enterocyte NFκB contributes to alterations in intestinal barrier function.

We hypothesized that inhibition of enterocyte NFκB exacerbates intestinal permeability in sepsis.

Mice lacking enterocyte IKKβ (resultant NFκB inhibition) were created via Cre/lox recombination under control of the villin promoter. Wildtype (WT) and IKKβ null (Vil‐Cre/IkkβF/Δ) mice underwent cecal ligation and puncture or sham laparotomy (n=5‐10/group). At 24 hr, intestinal permeability was measured in vivo with FD4. Claudin‐2, occludin, and ZO‐1 were evaluated by qRT‐PCR and fluorescent staining.

Septic WT mice had increased permeability compared to shams (495.1±46.5 vs. 297.8±15.7 ng/ml; p<0.01), while septic Vil‐Cre/IkkβF/Δ mice had augmented permeability (665.0±95.1 ng/ml; p<0.01). Claudin‐2 mRNA was increased in septic WT mice compared to shams (1.9±0.3 vs. 1.0±0.2; p<0.05) and septic Vil‐Cre/IkkβF/Δ mice had further increased claudin‐2 (3.22± 0.5; p<0.05). Claudin‐2 staining revealed a similar pattern. There were no differences in occludin or ZO‐1.

Inhibition of enterocyte NFκB exacerbates permeability and is associated with parallel changes in claudin‐2. Since inhibition of enterocyte NFκB augments gut apoptosis in sepsis, changes in permeability may be apoptosis‐dependent.
Hibernation increases cholesterol and apolipoprotein A‐I levels in ground squirrels
Authors: Otis Jessica P , Carey Hannah V
Published: June 2021

Studies in two ground squirrel species suggest expression of ApoA‐I increases in gut and liver during hibernation. Since ApoA‐I is the major lipoprotein in HDL particles, we hypothesized that hibernation alters cholesterol metabolism. To test this idea we measured cholesterol and lipoprotein levels, and changes in expression of genes that regulate their metabolism in summer (SUM) and hibernating (HIB) 13‐lined ground squirrels. Plasma cholesterol was ~2‐fold greater in HIB squirrels during torpor (T) (474.6 ± 44.8 mg/dl) and interbout arousal (IBA) (436.1 ± 56.2 mg/dl) than in SUM (219.1 ± 12.8 mg/dl, P<0.01); VLDL‐, LDL‐, and HDL‐cholesterol showed the same trend. ApoA‐I mRNA levels in liver and gut, and protein levels in plasma, liver and gut were greater in HIB (P<0.05 for all). Liver mRNA levels of ApoB, LXR, SREBP2 and the rate limiting enzyme in cholesterol synthesis (HMGR) were similar in SUM and HIB, but SREBP1c expression was lower in T compared with SUM and IBA (P<0.001). Protein expression of CYP7A1 (bile acid synthesis) was lower in HIB ((P<0.05). ABCA1 mRNA levels rose 13‐fold in gut of HIB, suggesting altered cholesterol processing in gut during hibernation. These results confirm significant seasonal changes in cholesterol and lipoprotein dynamics in ground squirrels. Understanding their causes and functional significance will shed light on adaptations to the lipid‐centric metabolism of hibernation.
Vascular Endothelial Growth Factor (VEGF) Receptor Inhibitors, SU11248 and SU5416, Directly Inhibit the Proliferation of Cultured ER‐positive and ER‐negative Human Breast Cancer Cells
Authors: Wells Jeremy , Young Emily , Tucker Kevan , Chawla Simran , Gu Jian‐Wei
Published: June 2021

The autocrine effects of VEGF on cancer cells are poorly understood. Present study determines if VEGF and its receptor are differentially expressed in ER‐positive (MCF‐7) and ER‐negative (MDA‐MB‐231) human breast cancer cells, and if VEGF receptor (VEGFR) inhibitors, SU11248 and SU5416, directly decrease the proliferation of those human breast cancer cells. MCF‐7 and MDA‐MB‐231 cells were cultured using RPMI 1640 media with 10% FBS. β‐estradiol increased VEGF expression in MCF‐7 cells (1762±56 vs.1136±58 pg/mg, P<0.01) but not in MDA‐MB‐231 cells. ELISA showed that VEGF and VEGFR‐2 were more highly expressed in ER‐negative cells than ER‐positive cells (>8‐fold, P<0.01). 3H‐thymidine incorporation showed that SU11248 (10 µmol/L) caused both a 77% and 75% decrease, and SU5416 (10 µmol/L) caused both a 56% and 36% decrease in the proliferations of MCF‐7 and MDA‐MB‐231 cells, respectively, compared to the control (P<0.01). The results indicate that VEGF and VEGFR are differentially expressed in ER‐positive and ‐negative breast cancer cells, and that SU11248 exerted a stronger effect than SU5416 on inhibiting the proliferation of both ER‐positive and negative human breast cancer cells. These findings support the hypothesis that VEGFR inhibitors, as an anti‐angiogenic therapy, also target the autocrine effects of VEGF to suppress both ER‐positive and ‐negative breast cancer progression. (HL51971 & AA013821)
Insulin resistance without elevated mTORC1 activity in muscles of mice fed a high fat diet for four or eight months
Authors: Cinquino Nicholas , Anthony Marcus , Phelps Charles B , Berk E Zachary , Reynolds Thomas H
Published: June 2021

The mammalian target of rapamycin complex 1 (mTORC1) appears to mediate the development of insulin resistance in cultured cells. In animal models of type 2 diabetes, the role of mTORC1 in the development of insulin resistance is not established. We studied in vivo insulin action and mTORC1 activity in skeletal muscles of mice fed a normal chow diet (CON) or a high fat diet (HFD) for four months (4M‐HFD) or eight months (8M‐HFD). As expected, insulin‐assisted glucose tolerance (IAGT) was significantly reduced in 4M‐HFD and 8M‐HFD mice compared to CON mice. Following four months of a HFD, mTORC1 activity was measured in muscles of mice 15 min following an intraperitoneal injection of insulin or saline. In the basal or insulin‐stimulated state, mTORC1 activity was similar in muscles of 4M‐HFD mice compared to CON mice. In 8M‐HFD mice, we determined the effect of acutely inhibiting mTORC1 activity on insulin action by administering rapamycin two hours prior to an IAGT test. Although in vivo rapamycin treatment abolished mTORC1 activity it did not improve insulin sensitivity. Finally, mTORC1 activity was assessed in muscles from 8M‐HFD and CON mice that did not receive insulin. No significant differences were observed in basal mTORC1 activity in muscles of 8M‐HFD mice compared to CON mice. Taken together these findings indicate that insulin resistance can occur without an increase in mTORC1 activity in skeletal muscle.
Aging increases susceptibility to western diet‐induced glucose intolerance and insulin resistance in mice
Authors: Russell Molly J , Folian Brian J , Durrant Jessica R , Connell Melanie L , Seals Douglas R , Lesniewski Lisa A
Published: June 2021

Aging may increase vulnerability for developing glucose‐insulin dysfunction with consumption of a high fat or "western" diet (WD). Young (Y, 6‐8 mo, N=4‐8/group) and old (O, 29‐31 mo, N=4‐8/group) B6D2F1 mice were fed normal chow (NC, 14% fat by kcal) or WD (40% fat) for 8 weeks. On NC during glucose tolerance tests the areas under the curves for glucose (AUCg) and insulin (AUCi) were not different (15815±665 vs. 14611±1261 mg/dl*min, Y vs. O, P=0.2) and greater (38.1±4.4 vs. 28.1±1.1 ng/ml*min, P<0.05), respectively, in O mice, but there were no age‐group differences (P=0.49) in glucose infusion rates (GIR) during hyperinsulinemic‐euglycemic clamps (6 mU/kg/min). WD increased AUCg in both Y and O (to 18175±653 and 19947±1889 mg/dl*min, respectively, both P=0.01), but increased the insulin response to a glucose challenge only in O mice (AUCi: 79.1±7.3 ng/ml*min, P<0.01 vs. ONC). Compared with NC, WD markedly reduced GIR in O mice (30±6 vs. 51±5 mg/kg/min, P< 0.05), but only tended to do so in Y mice (37±3 vs. 51±8 mg/kg/min, P< 0.1). The ratio of phosphorylated (ser307) to total insulin receptor substrate‐1, a cellular marker of insulin resistance, was greater after WD vs. NC in adipose tissue of O mice (0.99±0.1 vs. 0.75±0.1, P=0.07), but did not differ with diet in Y (P=0.4). Using two distinct methods for assessing glucose‐insulin function, our results offer strong evidence that aging increases susceptibility to WD‐induced development of insulin resistance. Impaired insulin signaling in adipose tissue may be an important mechanism underlying this effect.

NIH AG013038, AG006537, AG015897
Oxidative stress limits exercise‐ and insulin‐stimulated muscle glucose uptake (MGU) in conscious, chow‐fed C57BL/6J mice
Authors: Kang Li , Lustig Mary E. , Anderson Ethan J. , Lin Chien‐Te , Perry Christopher G.R. , Neufer P. Darrell , Wasserman David H.
Published: June 2021

Mitochondrial oxidative stress is associated with exercise‐induced muscular fatigue and insulin resistance. Catalase is an antioxidant enzyme catalyzing the breakdown of H2O2 into H2O and O2. We hypothesized that reducing oxidative stress by mitochondrial catalase overexpression would improve exercise‐ and insulin‐stimulated MGU. Muscle‐specific mitochondrial‐targeted catalase overexpressing mice (mCAT) and WT littermates were chow fed and studied at 16 wks of age. Arterial and venous catheters for sampling and infusion were implanted 5‐7 d prior to study. Rg, an index of MGU, was determined using 2‐deoxy[14C]glucose during 30 min of treadmill exercise or a 2h hyperinsulinemic‐euglycemic clamp. Fasting body weight, glucose, and insulin were the same in WT and mCAT mice. Arterial glucose and insulin were also similar in WT and mCAT mice during both exercise and the clamp. Exercise‐stimulated Rg was increased in soleus, gastrocnemius, and heart in mCAT vs WT mice. Insulin‐stimulated Rg was increased in gastrocnemius and vastus lateralis in mCAT vs WT mice. In conclusion, reduction in oxidative stress by mitochondrial catalase overexpression improved both exercise‐ and insulin‐stimulated MGU. This suggests that oxidative stress is a limitation to MGU under these conditions and mitochondrial antioxidants are potential targets for treatment of muscular fatigue as well as insulin resistance. (NIH DK54902)
Low salt intake during pregnancy and lactation causes growth delay and modifies lipid profile in adult female Wistar rat offspring.
Authors: Lopes Karen Lucasechi , Furukawa Luzia Naoko Shinohara , Heimann Joel Claudio
Published: June 2021

Objective

To evaluate body size and lipid profile in adult female offspring (off) in Wistar rats whose dams were fed low salt diet during pregnancy and lactation.

Methods

Female Wistar rats were fed low (LSD: 0.15%) or normal (NSD 1.3% NaCl) salt diet from 8 to 18 weeks of age. At 12 weeks of age, they were mated. Body weight (BW) was measured on the day of birth and since weaning all off groups were fed NSD. With 40 days of age, off from LSD and NSD groups were ovariectomized (OVX) or not (SHAM). At 12 weeks of age, OVX or SHAM rats were housed in 4oC or at room temperature (RT) during 24 hours and triacilglicerols (TG), cholesterol (CHO), naso‐anal length (NA) were measured.

Results

(mean±SEM, p<0.05, n= 5/group: BW (g) was lower at the birth in LSDoff (5.1±0.2) than in NSDoff (5.9 ±0.1). In SHAM, the NA (cm) was lower in LSDoff (20.3±0.1) than in.NSDoff (21.1±0.2). In OVX, NA in LSDoff (22±0.5) and NSDoff (22±0.2) were higher compared to the SHAM. TG (mg/dL) was lower at 4oC than at RT in LSDoff SHAM (25±3 vs. 96±23), however in NSDoff SHAM low temperature did not alter TG. In OVX groups, TG was lower in 4°C, both in NSDoff (RT = 122±19, 4°C = 45±7) and LSDoff (RT = 72±14, 4±C = 41±6). CHO decreased in response to 4ºC only in SHAM and OVX NSDoff.

Conclusions

Low salt diet during pregnancy and lactation causes growth delay and lipid alterations in response to low temperature. These effects are modified by OVX.

Supported by FAPESP
Metabolic adjustments in response to graded exercise depends on central angiotensin AT1‐receptors
Authors: Leite Laura Hora Rios , Lacerda Ana Cristina R. , Balthazar Cláudio H. , Marubayashi Umeko , Coimbra Cândido C.
Published: June 2021

To asses the influence of central angiotensin AT1 receptors on metabolic adjustments in rats during graded exercise on a treadmill, 2 μL of NaCl (Sal) or losartan (Los; 60 nmol) were intracerebroventricularly injected before running until fatigue (starting at 10 m/min, 1 m/min increment every 3 min until fatigue, 10% inclination). Oxygen consumption (VO2) was measured and mechanical efficiency (ME) calculated (n=6). The same protocol was used to collect blood samples through a jugular catheter (n=7). Plasmatic concentrations of glucose, lactate and free fatty acids (FFAs) were determined. During the first two steps of exercise, a similar increase in VO2 and equal ME were observed in both groups. Thereafter, VO2 continued to increase, but at a higher rate in Los‐treated animals, leading to a 34% reduction in ME in these animals (p<0.01). Los‐treated rats also showed a fast hyperglycemic response, already seen at low exercise intensities as 20% of maximal work. Higher lactate and FFAs levels followed this hyperglycemic response. The data shows that AT1‐receptor blockade during graded exercise increases metabolic cost, leading to decreased ME, hyperglycemia and higher FFA mobilization at lower levels of exercise intensities. We conclude that angiotensinergic blockade results in higher and premature sympathetic activation, shifting energy balance during graded exercise.

Supported by CNPq, FAPEMIG
IGF‐I SYSTEM TEMPORAL RESPONSES TO CALORIC RESTRICTION DURING CONTINUOUS MONITORING OF INTERSTITIAL GLUCOSE
Authors: Nindl Bradley Charles , Rarick Kevin R. , Scofield Dennis E. , Pierce Joseph R. , Stanger Michael J. , Adam Gina E. , Lieberman Harris R.
Published: June 2021

IGF‐I declines during caloric restriction, but few data are available that provide temporal resolution for IGF‐I and IGF‐I binding protein (BP) responses within the context of altered dietary intakes. This study examined temporal responses of the IGF‐I system and glucose concentrations during altered dietary intakes. A double‐blind, placebo‐controlled crossover design was used in which 27 subjects (24±yr) underwent 3, 48‐hr experimental treatments: 1) caloric restriction (CR) (313±9 kcal), 2) carbohydrate diet condition (CHO) (4566±111 kcal), and 3) carbohydrate‐fat (CHO/F) diet condition (4611±114 kcal). The MiniMed continuous glucose monitoring system measured interstitial glucose every 5 minutes. Blood was sampled periodically (6 timepoints total) for IGF‐I, IGFBPs‐1 and 3. A repeated measures ANOVA was used for statistical analysis (p < 0.05). Diet effects indicated IGFBP‐1 increased during CR (CR (33 ng/ml > CHO (17 ng/ml) = CHO/F (18 ng/ml) and glucose decreased during CR (CR (85 mg/dl < CHO (99 mg/dl) = CHO/F (97 mg/dl) with no changes for IGF‐I or IGFBP‐3. Also, IGFBP‐1 increased (~250%) from baseline after only 24 hrs, while IGF‐I declined (~7%) only after 48 hrs. IGFBP‐1 increased during CR, but was not altered with diets differing in CHO/F content. IGF‐I bioavailability is influenced by nutritional stress, independent of changes in IGF‐I.
Pro‐inflammatory effect of hyperglycemia in cultured macrophages and neonatal rat ventricular cardiomyocytes is blunted by inhibition of hexosamine biosynthesis
Authors: Zou Luyun , Lu Xiaoyin Tina , Marchase Richard B , Chatham John C.
Published: June 2021

We have previously shown that increasing protein O‐linked‐N‐acetylglucosamine (O‐GlcNAc) levels with glucosamine (GlcN) attenuated activation of cardiac NF‐kB signaling both in vivo and in vitro. However, there is also evidence to suggest that increased hexosamine biosynthesis (HB) and O‐GlcNAc levels contributes to the adverse effects of hyperglycemia. Therefore, the goal of this study was to compare the effects of high glucose (HG, 25mM) and glucosamine (GlcN, 5mM) on the response of neonatal rat ventricular cardiomyocytes (NRVM) and mouse leukaemic monocyte macrophages (Mφ) to LPS. LPS treatment for 6hrs (Mφ, 0.1µg/ml; NRVM, 2µg/ml) significantly increased iNOS expression in both Mφ and NRVM. In Mφ cells the LPS‐induced increase in iNOS was clearly augmented with HG and this was attenuated by pretreatment with the GFAT inhibitor DON (20µM). In NRVMs the effect of HG on LPS‐induced iNOS expression was less pronounced than that seen in Mφ cells; nevertheless, treatment with DON attenuated iNOS expression in HG treated cells. DON pre‐treatment also significantly decreased O‐GlcNAc levels in both Mφ and NRVM. In both Mφ and NRVM cells GlcN treatment increased O‐GlcNAc levels and prevented the LPS‐induced increase in iNOS. These results demonstrate that HG increases sensitivity to inflammatory stimuli that can be attenuated at least in part by inhibition of HB with DON. Paradoxically, however, direct activation of HB with GlcN blunted the pro‐inflammatory effects of LPS. This suggests that the pro‐inflammatory effects of HG may be mediated by a combination of increased HB combined with another glucose‐activated pathway.
Variable Effects of Caloric Restriction on Metabolic and Breathing Regulation Between Two Inbred Mouse Strains
Authors: Abston Eric D , Bishai John M , Mitzner Wayne , Tankersley Clarke G
Published: June 2021

The World Health Organization reports that ~800 million people worldwide are undernourished, corresponding to a daily mortality rate of 25,000 people. While altered metabolic and breathing characteristics occur with severe caloric restriction (CR), the mechanisms are unclear. We hypothesize that a robust genetic difference between C3H/HeJ (C3) and C57BL/6 (B6) mice lead to variation in metabolic and breathing regulation with CR. C3 and B6 mice (n = 8 per strain) were fed a diet equal to 33% of the daily food intake for 21 days. Using plethysmography, breathing characteristics were measured weekly on room air, and following acute hypercapnic (5% CO2) and hypoxic (10% O2) challenges. While the decline in body weight through 21 days of CR was similar in C3 vs. B6 strains (~40%), reductions in body temperature (10.0±1.8 vs. 2.8±1.0°C) and O2 consumption (1.36±0.32 vs. ‐0.04±0.16 ml/hr/g) were significantly (P < 0.01) lower in C3 relative to B6 mice. Minute ventilation (VE) on room air remained unchanged with CR in both strains, but hypercapnic and hypoxic VE were depressed incrementally though 14 days. By day 21 of CR, hypercapnic and hypoxic VE recovered in B6 but not in C3 mice. In conclusion, genetic factors determine variation in metabolic and breathing regulation during CR, allowing B6 mice to maintain indices of homeostasis closer to control values than C3 mice.
Metabolic Modeling of Acetate Transport and Metabolism in the Rat Brain
Authors: Shestov Alexander A , Deelchand Dinesh K , Henry Pierre‐Gilles
Published: June 2021

The aims of this study were first to determine kinetic parameters for acetate transport and utilization in the brain and then use this information to perform 13C dynamic modeling in order to determine absolute cerebral metabolic fluxes.

Previously measured in vivo 13C time courses obtained during infusion of [2‐13C] acetate in rat brain under morphine anesthetic at 9.4 T [1] were used for the modeling.

Fitted values for transport and uptake kinetics were: Vtrmax= 0.96 ± 0.18 μmol/g/min and KtrM= 4.2 ± 0.8 mM for acetate transport through the BBB and Vutmax=0.50 ± 0.08 μmol/g/min with KMut= 0.01 ± 0.14 mM for acetate utilization through the mitochondrial inner membrane and acetyl‐CoA synthetase from acetate. The steady‐state cerebral metabolic flux of acetate (CMRace) was 0.49 ± 0.08 μmol/g/min (mean ± SD; n = 4).

Metabolic fluxes determined from modeling of the 13C time courses were: VTCA(n)= 1.8 μmol/g/min, VTCA(g)= 0.27 μmol/g/min, VPC= 0.1 μmol/g/min, VX=1.4 μmol/g/min and VNT= 0.23 μmol/g/min.

Maximum transport capacity of acetate through the BBB was two‐hold higher than the maximum rate of brain acetate utilization and KtrM was much higher than KMut, implying that the rate‐limiting step for acetate metabolism occurs after acetate enters the brain.

[1] Deelchand et al. ISMRM 2006

This work was supported by NIH P41 RR008079, P30 NS057091 and R01 NS038672
Arsenic alters tight junction expression, distribution and function in human airway epithelial cells
Authors: Sherwood Cara L. , Liguori Andrew E. , Olsen Colin E. , Lantz R. Clark , Burgess Jefferey L. , Boitano Scott
Published: June 2021

The airway epithelium plays a role in the innate immune response, in part, due to a barrier that separates the air‐filled lumen from the underlying tissue. Three categories of membrane spanning tight junction proteins contribute to the establishment of this barrier, including, JAMs, Claudins, and Occludin. Arsenic is a natural metalloid toxicant that can accumulate in the lung via inhalation or ingestion. In animal and human studies, we and others have shown that arsenic ingestion can lead to altered lung function suggesting epithelial barrier dysfunction. In this report, we evaluated the effects of low‐level arsenic exposure on airway epithelial barrier function. We found that low levels of arsenic in growth medium delayed (30‐60 ppb) or prevented (290 ppb) the establishment of an airway epithelial monolayer in vitro. Addition of arsenic to pre‐formed in vitro monolayers reduced transepithelial resistance. Using immunocytochemistry, immunoblotting and quantitative real time RT‐PCR, we found that monolayers of airway epithelial cells exposed to 0, 60 or 290 ppb arsenic displayed altered and unique patterns of expression for JAM‐A, several Claudins (1, 2, 3, 4, 5, 7), and Occludin. In summary, exposure to environmentally significant doses of arsenic can induce functional and structural changes in the airway epithelial barrier. Grant Support: NIH P30‐ES006694, T32‐HL007249; EPA R832095.
Functional Characterization of Ca2+ and K+ Channels in Human Embryonic Stem Cells
Authors: Firth Amy L. , Yuan Jason X.‐J.
Published: June 2021

Human embryonic stem cell (hESC) expansion involves both self‐renewal and differentiation. Physiological properties of cell motility, migration and proliferation all require cytoplasmic Ca2+ and are regulated by a) membrane potential; b) spatial and temporal variations of intracellular Ca2+; and c) spatially‐ and temporally‐regulated expression of plasmalemmal receptors. Functional adaptation of Ca2+ and K+ channels in the plasma membrane may thus be an important prerequisite for hESCs to self‐renew, migrate into special niches or microenvironments and to differentiate into specific lineages. Using H9 hESC, changes in the voltage‐gated K+ (Kv) channels were closely related with the ability of hESC to differentiate into a smooth muscle like cell phenotype. The ion channel profile changed from a predominantly "A" type rapidly inactivating current to a delayed rectifier type current and correlated with an increase in expression of the Kv1 family of delayed rectifier K+ channels and a decrease in pluripotency markers OCT‐4 and NANOG. In addition, hESC express multiple transient receptor potential (TRP) channel subunits and passive depletion of Ca2+ from intracellular stores activated store‐operated Ca2+ entry. These data confirm that function and expression of certain ion channels in hESC differ from those in differentiated cell phenotypes such as smooth muscle cells and neurons, and the changes in channel activity are necessary for hESC to differentiate into functionally matured cells.

Funded by the NIH/NHLBI and CIRM.
REGULATION OF COLLECTING DUCT ENDOTHELIN‐1 PRODUCTION
Authors: Kohan Donald E. , Stricklett Peter K. , Chapman Mark E. , Strait Kevin A.
Published: June 2021

Collecting duct (CD)‐derived endothelin‐1 (ET‐1) is an important autocrine inhibitor of renal Na reabsorption; CD ET‐1 knockout causes marked hypertension. High Na intake augments CD ET‐1 release; the mechanisms involved are unknown. To assess this, primary cultures of rat inner medulla CD (IMCD) were studied. Cells exposed to flow had a 3‐4 fold increase in ET‐1 mRNA and intracellular Ca [Ca]i. Inhibition of calmodulin (CaM) or CaM kinase II, as well as chelation of [Ca]i, markedly reduced ET‐1 release and mRNA levels. Transfection with rat ET‐1 promoter‐luciferase constructs revealed maximal reporter activity, as well as sensitivity to CaM blockade, between the region 1319‐1725 bp 5' to the transcription start site. Incubation of this 406 bp region with IMCD nuclear extracts caused an electrophoretic mobility shift that was prevented by competition with a 125 bp fragment between 1455 and 1576 bp 5' to the transcription start site. This 122 bp region contains two NFAT sites. An antibody to NFAT‐5 caused a supershift, while oligos containing the NFAT consensus site reduced the shift. In vitro footprinting of the ‐1455 and ‐1576 bp region revealed protected areas at the NFAT consensus binding sites. Cyclosporine A (CyA), a calcineurin inhibitor, caused a 60% reduction in IMCD ET‐1 release. In contrast, in rat aortic endothelial cells, ET‐1 promoter‐luciferase activity was maximal in the proximal 500 bp promoter region and was not CaM regulated; further, CyA stimulated ET‐1 production. We propose that Na loading increases CD luminal flow, augmenting [Ca]i, activating CaM and calcineurin, leading to NFAT nuclear translocation and increased ET‐1 gene transcription. This pathway may be unique to CD.
Analysis of time dependent states of solute coupled water transport
Authors: Larsen Erik Hviid , Sørensen Jens Nørkær
Published: June 2021

At transepithelial equilibrium water uptake by toad skin epithelium is linearly correlated with the active Na+ flux. The present study aimed at analyzing the coupling between these fluxes during transition from one steady state to another. The short‐circuited isolated toad skin epithelium was studied in an Ussing setup with a horizontal capillary tube on the inside chamber. The volume was clamped by keeping the position of the meniscus in the capillary tube constant via a motor‐driven syringe the position of which was continuously recorded. When the isoproterenol stimulated short‐circuit current (ISC) and volume flow (JV) were stationary, 100 μM amiloride was added on the outside while the time courses of ISC and JV were followed until a new steady state was obtained. Initially, ISC = 18±4.1 μA/cm2 and JV = 1.3±0.4 nl/cm2/s (mean ± SEM, n = 9). Amiloride produced a relatively fast decrease of ISC with T1/2 = 1.6± 0.1 min, and a slow decrease of JV with T1/2 = 14.1± 2.3 min towards the new steady states of, ISC = ‐0.1±0.4 μA/cm2 and JV = 0.39±0.11 nl/cm2/s. Theoretical quantitative analysis was performed by solving the set of equations of our mathematical‐physical model for time dependent states, indicating that also during the imposed transient state JV is driven by the lateral Na/K‐pumps governed by the rate at which the cellular Na+ pool is emptied. Supported by The Danish Natural Science Research Council 272‐05‐0417.
Acute TiO2 exposure does not alter endothelial function in rat small mesenteric arteries
Authors: Martin Justin , Naik Jay
Published: June 2021

Owing to their high surface area to volume ratio, nanomaterials have potential benefits in industry, medicine, and household products. Although the use of nanomaterials is rapidly growing the physiological consequences of acute and chronic exposure have not been established. Indeed, short‐term (24 hr) nanomaterial exposure has been shown to increase reactive oxygen species generation (ROS) in epithelial cells in culture. An increase in ROS production within the vasculature could potentially elicit a decrease in NO bioavailability. Previous work has suggested that this increase in ROS production may involve cellular internalization. However, we hypothesized that nanomaterials interact with the endothelial cell surface resulting in an impaired endothelial‐dependent vasodilation. To this end, isolated, pressurized small mesenteric arteries (100 ‐ 250 μm) from Wistar rats were pre‐constricted with Phenylephrine (PE; 10−7 ‐ 10−6 M) and administered acetylcholine (ACh; 10−8 ‐ 10−6 M) in the presence of either vehicle or 0.05% v/v titanium dioxide (TiO2; 1 hr). ACh administration induced a dose‐dependent vasodilation. There were no statistically significant differences in the vasodilatory response to ACh between vehicle and TiO2 treated arteries. These results suggest that acute TiO2 exposure does not alter ACh induced vasodilation in small rat mesenteric arteries.
Modeling of gender differences in cardiovascular function during exercise using Quantitative Human Physiology
Authors: Hodnett Benjamin Lucas , Carter Cory Blake , Hester Robert
Published: June 2021

Quantitative Human Physiology (QHP) is an open‐source XML model of human physiology based on Quantitative Circulatory Physiology (QCP), a previous model from our department that incorporates over 4000 simultaneous equations. With QHP, the model has been expanded to include a female (F) subject, which will allow investigation of gender differences on human physiology. For this model, cardiovascular function was examined in a 78‐kg male (M) subject and a 60‐kg F subject. The protocol involved having the subjects perform 30‐min treadmill exercise protocol (2% incline at 2 miles/hour) and comparing cardiovascular parameters to pre‐exercise conditions. Circulatory parameters were analyzed as percent increases, due to the different baseline parameters between the M and F subjects. M and F skeletal muscle (SKM) masses were 27 and 20 kg, respectively. Following 30 min of exercise, M cardiac output (CO) increased 104% whereas F CO increased 92% (Figure). Interestingly, while net SKM perfusion was greater in the M than the F (6.7 L/min vs. 3.5 L/min), the percent increase values were greater in the F than the M (1022% vs. 823%). This model will investigate the physiological mechanisms underlying these differences in cardiovascular function between M and F, including the role of differences in sympathetic function, catecholamine release, and non‐SKM perfusion. Supported by NSF EPSCoR and NIH HL‐51971.
Increased arterial blood pressure and volume expansion in Atrap (angiotensin receptor‐associated protein) – deficient mice
Authors: Oppermann Mona , Castrop Hayo
Published: June 2021

Atrap is an interacting protein of angiotensin AT1 receptors and was shown to facilitate AT1 receptor internalization in vitro. To further assess the in vivo function of Atrap, we generated Atrap‐deficient mice by gene targeting.

Atrap‐deficient mice were viable, fertile and showed no gross abnormalities. Atrap protein in the kidney was localized to the proximal tubules. We found no Atrap expression in the renal vasculature or in JG cells. Systolic arterial blood pressure (telemetry) was elevated in Atrap‐/‐ compared to +/+ mice averaging 120.3±0.7 vs. 111.7±1.4 mm Hg (n=5, 72 hrs‐measurement, p=0.001). Dose‐response curves of arterial blood pressure after bolus angiotensin II infusion were similar in both genotypes. Plasma renin concentration (PRC) was markedly reduced in Atrap‐/‐ compared to +/+ (49±4 vs. 100±13 ng Ang I/mL/hr, n=40 and 37, respectively; p<0.001). After acute furosemide administration PRC increased 13.2±2 fold in Atrap‐/‐ and 9.9±1.8 fold in +/+ (p=0.34) indicating an intact renin secretory capacity in Atrap‐/‐ mice. Plasma volume was increased in Atrap‐/‐ compared to wild types (4.1±0.2 vs. 3.1±0.2% of body weight, n=18 and 13; p<0.002).

In summary, Atrap‐deficient mice are hypertensive, volume expanded, and show a suppressed renin system. We suggest that Atrap acts as a negative regulator of AT1 receptors and that Atrap may be involved in the control of proximal tubular function.
Soluble guanylyl cyclase and phosphodiesterase 2A contribute to lung injury from intra‐tracheal LPS in mice
Authors: Rentsendorj Otgonchimeg , Schmid Eric P , D'Alessio Franco R , Aggarwal Neil R , Stephens R Scott , Servinsky Laura E , Pearse David P
Published: June 2021

In animal models of lipopolysaccharide‐induced acute lung injury (LPS‐ALI), increased NO production from endothelial nitric oxide synthase (eNOS) and inducible NOS (iNOS) contributes to alveolitis and epithelial barrier dysfunction. The toxic effects of NO have been attributed to peroxynitrite, but NO also generates cGMP through soluble guanylyl cyclase (sGC). Cytokines have been shown to increase human umbilical vein endothelial expression of phosphodiesterase 2A (PDE2A) in vitro (Surapisitchat et al. Circ Res 2007). PDE2A is a dual‐function PDE stimulated by cGMP to hydrolyze cAMP, a potent barrier‐protective molecule. We hypothesized that sGC and PDE2A contribute to LPS‐ALI. To test this, we administered intratracheal LPS (3.75 μg/g body weight) or diluent to anesthetized C57BL6 mice pretreated with the sGC inhibitor ODQ (10 mg/kg ip 1 hr before), the PDE2A inhibitor BAY 60‐7550 (3 mg/kg 1 hr before) or intraperitoneal (ip) diluent. At 6 hrs, the mice were reanesthetized for unilateral bronchoalveolar lavage (BAL) and lung harvesting. LPS increased BAL leukocytes, LDH and protein indicating alveolitis. LPS also increased lung Ser1177 eNOS phosphorylation, iNOS mRNA and PDE2A mRNA and protein expression. LPS did not alter sGC expression. sGC inhibition significantly attenuated the LPS‐induced increase in iNOS mRNA, BAL leukocytes and BAL LDH activity indicating an injurious role for sGC‐derived cGMP. PDE2A inhibition decreased iNOS mRNA and BAL LDH activity suggesting that PDE2A was also involved. We conclude that LPS‐induced activation of sGC in combination with LPS‐induced PDE2A expression contribute to LPS‐ALI in mice.

Supported by AHA Grant‐In‐Aid