DOI: 10.1556/2060.106.2019.19

Abstract: The recent explosion of scientific interest in the gut microbiota has dramatically advanced our understanding of the complex pathophysiological interactions between the gut and multiple organs in health and disease. Emerging evidence has revealed that the gut microbiota is significantly altered in patients with chronic kidney disease (CKD), along with impaired intestinal barrier function. These alterations allow translocation of various gut-derived products into the systemic circulation, contributing to the development and progression of CKD and cardiovascular disease (CVD), partly mediated by chronic inflammation. Among potentially toxic gut-derived products identifiable in the systemic circulation, bacterial endotoxin and gut metabolites (e.g., p-cresyl sulfate and trimethylamine-N-oxide) have been extensively studied for their immunostimulatory and atherogenic properties. Recent studies have also suggested similar biological properties of bacterial DNA fragments circulating in the blood of patients with CKD, even in the absence of overt infections. Despite the accumulating evidence of the gut microbiota in CKD and its therapeutic potential for CVD, the precise mechanisms for multidirectional interactions between the gut, kidney, and heart remain poorly understood. This review aims to provide recent evidence on the associations between the gut microbiota, CKD, and CVD, and summarize current understanding of the potential pathophysiological mechanisms underlying the “gut–kidney–heart” axis in CKD.

Keywords: bacterial DNA, cardiovascular disease, chronic kidney disease, constipation, end-stage renal disease, microbiome, permeability, uremic toxins

DOI: 10.1556/2060.106.2019.21

Abstract: Purpose: Consumption of alternative flours, such as sprouted chickpea flour, has shown increased popularity in recent years. Foods rich in antioxidants have been shown to influence brachial artery flow-mediated dilation (FMD), a non-invasive test of a crucial layer of the artery called the endothelium. Partially replacing the semolina flour in pasta with sprouted chickpea flour (SCF) may acutely affect endothelial function post-digestion. We sought to determine if FMD was higher, lower, or the same post-digestion of pasta made with 60% semolina flour and 40% SCF (SCF40) vs. post-digestion of pasta made with 100% semolina flour (SEM100, i.e., control). Methods: Trolox equivalent antioxidant capacity (TEAC) analysis was performed on the same flour samples. Healthy participants underwent a screening visit and two randomized controlled meal data collection visits (SCF40 and SEM100). At each data collection visit, participants consumed 255 g of pasta with butter. FMD was assessed 2–3 h after pasta consumption. Results: TEAC results showed that SCF40 (2.031 ± 0.096 mmol trolox/100 g sample) had significantly greater antioxidant capacity than SEM100 (1.736 ± 0.046 mmol trolox/100 g sample; p = 0.02). Twenty-two healthy participants (5 men and 17 women; 26 ± 2 years, 66.6 ± 2.3 kg, BMI = 24 ± 1 kg/m2, SBP = 114 ± 3 mmHg, DBP = 75 ± 2 mmHg, HR = 74 ± 3 BPM) were studied. FMD in the SCF40 condition (10.3% ± 1.2%) was greater than the SEM100 condition (7.9% ± 0.8%, p = 0.02). Conclusion: These data suggest that partial substitution with sprouted chickpea flour in place of semolina flour in pasta acutely improves post-digestion FMD, which may be beneficial for cardiovascular health (ClinicalTrials.gov Identifier: NCT03801486).

Keywords: germinated, garbanzo, endothelial, vascular, antioxidant, dietary

DOI: 10.1556/2060.106.2019.24

Abstract: Background and aims: In this study, we aimed to investigate the effects of 10 weeks of high-intensity interval training (HIIT) and endurance training (END) on irisin, betatrophin, insulin, fasting blood glucose (FBG) concentrations, and lipid profiles in diabetic rats. Methods: Twenty-four Wistar rats (weight: 200–250 g) were randomly assigned into four groups as follows: (1) control (Cnt), (2) diabetic (Dibt), (3) diabetic HIIT (Dibt-HIIT), and (4) diabetic END (Dibt-END). For inducing diabetes, after 12 h of food starvation, nicotinamide (120 mg/kg) and streptozotocin (STZ; 65 mg/kg) were intraperitoneally injected. The diabetic training groups received 10 weeks of HIIT or END training following the induction of diabetes. Twenty-four hours following the last training session, blood serum samples were collected for evaluating the concentration of irisin, betatrophin, and insulin hormones through enzymelinked immunosorbent assay. Results: FBG and lipid profiles were measured by biochemical kits. A significant increase in the serum concentration of irisin (p < 0.05), betatrophin (p < 0.05), and insulin (p < 0.001) and significant decrease in the FBG (P < 0.01) and lipid profiles (p < 0.01) were observed in the Dibt-HIIT group compared to the Dibt-END group. In addition, irisin revealed a significant positive association with betatrophin and insulin values in diabetic training groups (p < 0.01). Conclusions: It seems that HIIT leads to a more extensive improvement in diabetic conditions compared to the END training. Therefore, HIIT appears to be an important time-efficient approach for the treatment of type 2 diabetes.

Keywords: diabetes mellitus, exercise, endurance training, insulin, streptozotocin

DOI: 10.1556/2060.106.2019.20

Abstract: Objectives: Impaired intestinal barrier function has been demonstrated in the pathophysiology of diarrheapredominant irritable bowel syndrome (IBS-D). This study aimed to describe the intestinal ultrastructural findings in the intestinal mucosal layer of IBS-D patients. Methods: In total, 10 healthy controls and 10 IBS-D patients were analyzed in this study. The mucosa of each patient’s rectosigmoid colon was first assessed by confocal laser endomicroscopy (CLE); next, biopsied specimens of these sites were obtained. Intestinal tissues of IBS-D patients and healthy volunteers were examined to observe cellular changes by transmission electron microscopy (TEM). Results: CLE showed no visible epithelial damage or inflammatory changes in the colonic mucosa of IBS-D compared with healthy volunteers. On transmission electron microscopic examination, patients with IBS-D displayed a larger apical intercellular distance with a higher proportion of dilated (>20 nm) intercellular junctional complexes, which was indicative of impaired mucosal integrity. In addition, microvillus exfoliation, extracellular vesicle as well as increased presence of multivesicular bodies were visible in IBS-D patients. Single epithelial cells appeared necrotic, as characterized by cytoplasmic vacuolization, cytoplasmic swelling, and presence of autolysosome. A significant association between bowel habit, frequency of abdominal pain, and enlarged intercellular distance was found. Conclusion: This study showed ultrastructural alterations in the architecture of intestinal epithelial cells and intercellular junctional complexes in IBS-D patients, potentially representing a pathophysiological mechanism in IBS-D.

Keywords: diarrhea-predominant irritable bowel syndrome, intercellular junctional complex, transmission electron microscopy, extracellular vesicles, intestinal barrier

DOI: 10.1556/2060.106.2019.16

Abstract: Background: Premenopausal women show a higher incidence of orthostatic hypotension than age-matched men, but there are limited data available on sex differences in cardiovascular responses to orthostatic challenge in healthy older persons. We investigated sex differences in hemodynamic and autonomic responses to orthostatic challenge in healthy older males and females. Materials and methods: Fourteen older healthy women and 10 age-matched men performed a sit-to-stand test (5 min of sitting followed by 5 min of standing). A Task Force® Monitor continuously measured the following beat-to-beat hemodynamic parameters: heart rate, systolic blood pressure, diastolic blood pressure, mean blood pressure, stroke index, cardiac index, and total peripheral resistance index. Cardiac autonomic activity, low-frequency (LF: 0.04–0.15 Hz) normalized (LFnuRRI) and high-frequency (HF: 0.15–0.4 Hz) normalized (HFnuRRI) components, and the ratio between LF and HF power (LF/HF) were calculated using power spectral analysis of heart rate variability. Results: Across all hemodynamic parameters, there were no significant differences between the sexes at baseline and during standing. LFnuRRI (median: 70.2 vs. 52.3, p < 0.05) and LF/HF ratio (median: 2.4 vs. 1.1, p < 0.05) were significantly higher, whereas HFnuRRI (median: 29.8 vs. 47.7, p < 0.05) was lower among women at baseline. All other heart rate variability measures did not differ between the sexes. Conclusions: The data indicate that older women showed higher sympathetic and lower parasympathetic activity at rest compared to age-matched men. These results are contradictory to the observations from previous studies, which showed a reduced sympathetic and enhanced parasympathetic activity in women in all ages. Further studies are required to determine the underlying mechanisms contributing to higher incidence of orthostatic hypotension in older females.

Keywords: sex differences, postmenopausal women, orthostatic hypotension, falls, autonomic activity

DOI: 10.1556/2060.106.2019.22

Abstract: Purpose: Glioblastoma cells create glutamate-rich tumor microenvironment, which initiates activation of ion channels and modulates downstream intracellular signaling. N-methyl-D-aspartate receptors (NMDARs; a type of glutamate receptors) have a high affinity for glutamate. The role of NMDAR activation on invasion of glioblastoma cells and the crosstalk with α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) is yet to be explored. Main methods: LN18, U251MG, and patient-derived glioblastoma cells were stimulated with NMDA to activate NMDAR glutamate receptors. The role of NMDAR activation on invasion and migration and its crosstalk with AMPAR were evaluated. Invasion and migration of glioblastoma cells were investigated by in vitro trans-well Matrigel invasion and trans-well migration assays, respectively. Expression of NMDARs and AMPARs at transcript level was evaluated by quantitative real-time polymerase chain reaction. Results: We determined that NMDA stimulation leads to enhanced invasion in LN18, U251MG, and patient-derived glioblastoma cells, whereas inhibition of NMDAR using MK-801, a non-competitive antagonist of the NMDAR, significantly decreased the invasive capacity. Concordant with these findings, migration was significantly augmented by NMDAR in both cell lines. Furthermore, NMDA stimulation upregulated the expression of GluN2 and GluA1 subunits at the transcript level. Conclusions: This study demonstrated the previously unexplored role of NMDAR in invasion of glioblastoma cells. Furthermore, the expression of the GluN2 subunit of NMDAR and the differential overexpression of the GluA1 subunit of AMPAR in both cell lines provide a plausible rationale of crosstalk between these calcium-permeable subunits in the glutamate-rich microenvironment of glioblastoma.

Keywords: calcium-permeable AMPAR, glutamate receptor, migration, NMDAR, signaling

DOI: 10.1556/2060.106.2019.25

Abstract: It has been shown that the tissue oxygen index (TOI) measured by near-infrared spectroscopy oscillates at very low frequencies during recovery after exercise and that this oscillation is derived from interactions among biochemical substances involved in oxidative metabolism in skeletal muscle. As a further step, we examined whether TOI in muscle interacts through oscillation with factors related to oxygen in the cardiorespiratory system. For this examination, coherence and phase difference between the TOI in the vastus lateralis and heart rate (HR) and between TOI and arterial oxygen saturation (SpO2) were sequentially determined during recovery (2–60 min) after severe cycle exercise with a workload of 7.5% of body weight for 20 s. Significant coherence between TOI and HR was obtained in the very low-frequency band (approximate range: 0.002–0.03 Hz) and in the low-frequency band (approximate range: 0.06–0.12 Hz). The phase difference was negative in the low-frequency band and positive in the very low-frequency band. The coherence between TOI and SpO2 was significant in the very low-frequency band. The phase difference was negative. There were no sequential changes in these coherences and phase differences. The results suggest that TOI in skeletal muscle interrelates with factors related to the heart and lungs.

Keywords: coherence, cardiorespiratory system, tissue oxygen index, oscillation, recovery from exercise

DOI: 10.1556/2060.106.2019.27

Abstract: Nicotine and cocaine- and amphetamine-regulated transcripts (CART) have several overlapping functions, such as the regulation of reward, feeding behavior, stress response, and anxiety. Previous studies showed that nicotine regulates CART expression in various brain regions. However, the molecular mechanisms underlying this regulation are not known. This study investigated the regulatory effect of nicotine on promoter activity of the CART gene in PC12 cells, which were differentiated into a neuronal phenotype by nerve growth factor (NGF) treatment. Two vectors containing reporter genes (Gaussia luciferase or mCherry) and the 1,140-bp upstream of the transcriptional start site of the mouse CART gene are used to analyze the CART promoter activity. Transient transfection of PC12 cells with either vector displayed strong promoter activity in both undifferentiated and differentiated PC12 cells. CART promoter activity in the PC12 cell line is increased by forskolin or NGF treatment. In differentiated PC12 cells, exposure to 50 nM nicotine for 6 h increased CART promoter activity. However, treatment with higher nicotine doses for 6 h and treatment with all nicotine doses for 24 h showed no effect. A nicotine concentration of 50 nM is comparable to brain nicotine levels experienced by chronic smokers over long periods of time. Taken together, these data indicate that nicotine may exert some of its actions through the regulation of CART transcription in the brain.

Keywords: nicotine, CART, forskolin, PC12, promoter

DOI: 10.1556/2060.106.2019.18

Abstract: Background: Inflammation plays a major role in the development of metabolic syndrome (MetS) and its progression. Recent studies have shown that pentraxin-3 (PTX-3), osteoprogerin (OPG), and tumor necrosis factor-alpha (TNF-α) are key factors in MetS pathophysiology, but evidence for endorsing their clinical use is currently unclear and insufficient. Aim: The study aimed to evaluate the association between the inflammatory biomarkers’ levels and the severity of MetS. Methods: The study was observational, transversal, prospective, cohort, and analytical type. We enrolled 80 patients (M:F = 1, mean age = 55 ± 10.77 years) who met MetS criteria. The study protocol included: medical history, physical examination, 6-min walk test distance (6MWTD), biochemical tests, electrocardiogram, echocardiography, and carotid ultrasonography. We also performed plasmatic measurement of PTX-3, OPG, and TNF-α, in addition to standard biochemical tests. Results: Subjects with severe MetS had higher values of body mass index (BMI) and waist circumference (p < 0.001, p = 0.001). PTX-3 levels were significantly higher in patients with severe MetS (p = 0.03) and the values were not influenced by age or gender. OPG positively correlated with BMI (r = 0.264, p = 0.018). 6MWTD was lower in patients with severe MetS (p = 0.005), whereas CCA-IMT was higher in this group of patients (p = 0.005). In addition, the receiver operating characteristic (ROC) curve analysis for PTX-3 identified a cut-off value of 10.7 ng/dl that differentiates between mild and severe MetS [AUC 0.656; sensitivity = 47.1% (95% CI = 36.1%–62.3%); specificity = 78.9% (95% CI = 54.4%–93.9%)]. Conclusion: PTX-3 was correlated with the severity of MetS, with other inflammatory parameters and cardiovascular tests. CCA-IMT and 6MWTD are useful in differentiating between mild and severe MetS.

Keywords: pentraxin-3, osteoprotegerin, tumor necrosis factor-alpha, metabolic syndrome, atherosclerosis

DOI: 10.1556/2060.106.2019.28

Abstract: Background and aims: The aim of this study was to evaluate changes in fat oxidation rate during 40 min of continuous exercise and identify the intensity at the highest fat oxidation rate (Fatmax). Methods: A total of 14 sedentary males with age, body height, weight, and BMI averages of 29.3 ± 0.7 years, 178.3 ± 1.7 cm, 81.1 ± 3.9 kg, and 25.4 ± 0.9 kg/m2, respectively, were included in the study. Fatmax was determined using an indirect calorimeter with an incremental treadmill walking test at least after 12 h of fasting. On a separate day, at least after 12 h of fasting, the participants walked for 40 min within their predetermined individual Fatmax heart rate and speed ranges. Results: The initial fat oxidation rate was not sustained within the first 16 min of exercise and was reduced; however, carbohydrate oxidation reached a stable level after nearly 10 min. Conclusions: In sedentary individuals, during low-intensity physical activity, fat oxidation rates may not be sustainable as expected from Fatmax testing. Therefore, when exercise is prescribed, one should consider that the fat oxidation rate might decrease in sedentary overweight individuals.

Keywords: exercise, lipid oxidation, carbohydrate oxidation, substrate metabolism, sedentary