Safety and efficacy of using cereal food (Frugra®) to improve blood pressure and bowel health in patients undergoing chronic hemodialysis: A pilot study

Hypertension and constipation are major hemodialysis complications. Salt restriction is one of the most important nonpharmacological interventions in managing hypertension. In patients undergoing hemodialysis, nonpharmacological strategies to manage constipation are extremely difficult to develop owing to the presence of excess dietary potassium and fluids. Frugra®, which is a cereal food that has a low salt content of 0.5 g per serving, may help reduce salt intake. Additionally, Frugra is rich in dietary fiber, thereby beneficial for such patients. In this study, we evaluated the safety and efficacy of Frugra in patients undergoing hemodialysis, focusing mainly on blood pressure and bowel health by changing the usual breakfast meal to Frugra for 8 weeks. We enrolled 11 patients undergoing hemodialysis. Despite the absence of changes in the patients' dry weight levels, their systolic blood pressure levels decreased from 155.5 ± 20.9 mmHg to 137.9 ± 10.3 mmHg after 2 months (P < 0.05). All participants reported improvements in bowel movement, and the levels of indoxyl sulfate, a representative gut-derived uremic toxin, were decreased from 49.3 μg/ml to 33.4 μg/ml. Furthermore, adverse events including electrolyte abnormalities were not observed. Therefore, Frugra may be useful to manage the health of patients undergoing hemodialysis.

Circadian rhythm of plasma and urinary angiotensinogen in healthy volunteers and in patients with chronic kidney disease

The urinary angiotensinogen (AGT) excretion rate could be a novel biomarker for the intrarenal activity of the renin-angiotensin system. Little is known about the circadian rhythm of AGT levels in plasma or urine. In this short article, making use of data in plasma and urine of healthy volunteers and patients with chronic kidney diseases, we first report that we were unable to find evidence for a circadian rhythm of AGT under any condition. Next we critically discuss to what degree elevated urinary AGT levels might be considered an independent biomarker that is not simply the non-specific consequence of proteinuria.

Involvement of advanced glycation end product-induced asymmetric dimethylarginine generation in endothelial dysfunction

Asymmetric dimethylarginine (ADMA), an endogenous nitric oxide synthase inhibitor, plays a role in endothelial dysfunction, an initial step of atherosclerosis. Advanced glycation end products (AGEs) also contribute to accelerated atherosclerosis. However, a pathophysiological crosstalk between ADMA and AGEs remains unclear. In this study, we investigated the relationship between ADMA and AGE level in patients with end-stage renal disease (ESRD) due to diabetic nephropathy. We also examined whether and how AGEs increased ADMA generation by cultured endothelial cells (ECs). Plasma ADMA levels were positively associated with serum AGE level and were inversely correlated with endothelial function determined by flow-mediated vasodilatation. AGEs dose dependently increased reactive oxygen species (ROS) generation in ECs, which was blocked by antisense DNA raised against receptor for AGEs (RAGE). Furthermore, AGEs decreased messenger RNA (mRNA) level of dimethylarginine dimethylaminohydrolase (DDAH)-II, an enzyme for ADMA degradation, reduced its total enzymatic activity and resultantly increased ADMA, all of which were completely blocked by an antioxidant, N-acetylcysteine. These results suggest that the AGE-RAGE-mediated ROS generation could be involved in endothelial dysfunction in diabetic ESRD patients partly by increasing the ADMA generation via suppression of DDAH activity in ECs.

Telmisartan inhibits AGE-induced podocyte damage and detachment

Advanced glycation end products (AGE) formed at an accelerated rate under diabetes, could cause podocyte apoptosis, thereby being involved in the development and progression of diabetic nephropathy. Renin-angiotensin system (RAS) plays a role in diabetic nephropathy as well. However, it remains unknown whether there exists a pathophysiological crosstalk between the RAS and AGE in podocyte damage in diabetic nephropathy. Therefore, this study investigated the effects of telmisartan, an angiotensin II (Ang II) type 1 receptor (AT1R) blocker on AGE or Ang II-induced podocyte damage in vitro. We further examined here the effects of AGE on AT1R expression levels in podocytes. AGE or Ang II not only increased DNA damage of podocytes which was evaluated by comet assay, but also induced cell detachment, both of which were significantly blocked by the treatment with telmisartan. AGE significantly increased AT1R levels in podocytes, whereas podocyte Ang II production was modestly stimulated by AGE. Telmisartan alone did not affect the release of lactate dehydrogenase from podocytes. Our present study suggests that AGE could induce podocyte DNA damage and detachment partly via stimulation of the Ang II-AT1R axis, thus providing a novel beneficial aspect of telmisartan in diabetic nephropathy.

Important aspects of urine sampling for angiotensinogen measurement: time and preservation conditions in healthy individuals

Intrarenal renin-angiotensin system (RAS) plays an important role for the pathogenesis of renal injuries. Experimental studies have demonstrated that angiotensinogen levels in renal tissues reflect the activity of intrarenal RAS. However, dynamics of urinary angiotensinogen have not been investigated in detail. Therefore, we examined the preservation conditions of the measured values of urinary angiotensinogen concentrations and an ultradian rhythm of urinary angiotensinogen excretion in humans. Urine samples were collected from 24 healthy volunteers. The urinary concentrations of angiotensinogen were measured by using ELISA. Two different urine preservation conditions were examined. One cycle of freeze-and-thaw did not change the measured values of urinary angiotensinogen concentrations. Moreover, to keep urine samples at room temperature for 12 hours did not change the measured values of urinary angiotensinogen concentrations. Thus, preservation conditions do not change the measured values of urinary angiotensinogen concentrations. Regarding an ultradian rhythm, blood pressure and the urinary concentrations of angiotensinogen were measured at 09:00, 13:00, and 16:00. The averaged levels of blood pressure were similar over the time. The average of urinary angiotensinogen/creatinine (Cr) ratios was 8.73 ± 1.15 ng/mg Cr at 09:00, 9.53 ± 1.58 ng/mg Cr at 13:00, and 8.58 ± 1.26 ng/mg Cr at 16:00. The urinary angiotensinogen excretion in healthy volunteers does not have an ultradian change during the daytime (P = 0.482). This may be another indication that the intrarenal RAS is independent of the systemic RAS. We have to pay attention to these findings in handling urine samples for measurements of angiotensinogen.

Head-shape polymorphism in Japanese eels Anguilla japonica in relation to differences of somatic growth in freshwater and brackish habitats

The age, total length (L(T)), head shape and skull shape were investigated for 379 Japanese eels Anguilla japonica sampled in freshwater and brackish areas of the Kojima Bay-Asahi River system, Okayama, Japan, to learn about the differentiation process of head-shape polymorphism. The relative mouth width (ratio of mouth width to L(T)) of A. japonica > 400 mm L(T) collected in fresh water was significantly greater than that of fish collected in brackish water. Growth rates of mouth width and the distance from the snout to the midpoint of the eyes (the ratio of width and distance to age, respectively) were not significantly different between freshwater and brackish-water samples, whereas the somatic growth rate (the ratio of L(T) to age) of freshwater samples was significantly lower than that of brackish-water eel samples. These results suggest that the factors affecting head and somatic growth of A. japonica are not identical. According to these results and feeding patterns in each habitat reported by another study, it is suggested that somatic growth appears to play a significant role in the differentiation process of the head-shape polymorphism in A. japonica, with the slow-growing fish in fresh water becoming broad-headed and the fast-growing fish in brackish water becoming narrow-headed.

Serum levels of advanced glycation end products (AGEs) are independently correlated with circulating levels of dipeptidyl peptidase-4 (DPP-4) in humans

OBJECTIVES

Inhibition of dipeptidyl peptidase-4 (DPP-4) has been proposed as a potential therapeutic target for type 2 diabetes. Although soluble DPP-4 has been identified in human serum and could be associated with DPP-4 activity, the kinetics and regulation of circulating DPP-4 levels remain unknown. In this study, we examined which anthropometric and metabolic variables, including serum levels of advanced glycation end products (AGEs), were independently associated with serum DPP-4 levels. Further, we investigated the effects of AGEs on DPP-4 expression in, and soluble DPP-4 release from human cultured proximal tubular epithelial cells.

DESIGN AND METHODS

The study involved 432 consecutive outpatients (301 males and 131 females; mean ages 61.8 ± 8.8) who underwent complete history and physical examinations, and determinations of blood chemistry and anthropometric variables. Serum DPP-4 and AGE levels were examined by enzyme-linked immunosorbent assay. Protein expression levels of DPP-4 and its release from the cells were analyzed with western blot analysis.

RESULTS

Mean serum levels of DPP-4 and AGEs were 520.2 ± 39.9 ng/mL and 8.96 ± 2.57 U/mL, respectively. In multiple regression analysis, female (p<0.001), HDL-cholesterol (p<0.001), glycated hemoglobin (p<0.001), AGEs (p<0.03), and the absence of hypertension medication (p<0.05) are independently associated with DPP-4 levels (R(2)=0.167). Western blot analysis revealed that AGEs significantly increased DPP-4 expression in, and soluble DPP-4 release from tubular cells.

CONCLUSIONS

The present study reveals that serum levels of DPP-4 are independently associated with various metabolic parameters in a general population. AGEs may up-regulate cellular DPP-4 expression and subsequently increase circulating levels of DPP-4 in humans.

Abstract 399: The Circadian Rhythm of Plasma Angiotensinogen in Healthy Volunteers

Background: We have previously reported that urinary angiotensinogen (AGT) excretion did not have a circadian rhythm and could be a novel biomarker for the activity of the renin-angiotensin system (RAS) in kidney. However, there have been few reports investigating the circadian rhythm of plasma AGT in human body. Thus, this study was performed to examine the circadian rhythm in plasma AGT in human.

METHODS: Evaluating RAS in clinical practice is generally performed in a recumbent position after a 30-minute stabilization period. However, to determine the necessity of recumbent position, we first compared plasma AGT concentrations measured right after waking up and after a 5-minute sitting rest. Next, we examined the circadian rhythm of plasma AGT in 43 healthy volunteers who had shown no abnormalities in the medical examinations in 2011. Plasma AGT was measured at three time points (9 a.m., 1 p.m., and 4 p.m.) in the above volunteers. Blood was collected by a micro hematocrit capillary tube with heparin, frozen for storage after centrifugation, and thawed for the measurement of plasma AGT using an ELISA kit.

Results: There was no significant difference between the plasma AGT values of the two measuring methods (P = 0.1202, n = 5). Based on the result, we performed blood sampling after a 5-minute sitting rest in the volunteers consisting of 17 men and 26 women. Average blood pressure was 116.3/75.1 mmHg at 9 a.m., 116.3/71.9 mmHg at 1 p.m., and 115.5/70.1 mmHg at 4 p.m.; average pulse rate was 78.7/min at 9 a.m., 77.1/min at 1 p.m., and 73.3/min at 4 p.m. Blood pressure and pulse rate did not change throughout the day. Average plasma AGT was 20.4 ± 6.0 ng/ml at 9 a.m., 20.7 ± 5.0 ng/ml at 1 p.m., and 19.8 ± 6.4 ng/ml at 4 p.m. Plasma AGT did not show a circadian rhythm (P = 0.3803).

Conclusion: We found in this study that plasma AGT did not have a circadian rhythm. We also found that plasma AGT was not affected by daily life actions. Thus, future patients may not be required to rest nor wait for certain time points before measuring plasma AGT. We also have to unveil the normal AGT levels and the influence on the levels by diseases. As we think that plasma AGT and ratio of urinary AGT to plasma AGT can be a new surrogate marker of hypertension and kidney diseases, we further need to go into this research area.

Early treatment with olmesartan prevents juxtamedullary glomerular podocyte injury and the onset of microalbuminuria in type 2 diabetic rats

BACKGROUND

Studies were performed to determine if early treatment with an angiotensin II (Ang II) receptor blocker (ARB), olmesartan, prevents the onset of microalbuminuria by attenuating glomerular podocyte injury in Otsuka Long-Evans Tokushima Fatty (OLETF) rats with type 2 diabetes mellitus.

METHODS

OLETF rats were treated with either a vehicle, olmesartan (10 mg/kg/day) or a combination of nonspecific vasodilators (hydralazine 15 mg/kg/day, hydrochlorothiazide 6 mg/kg/day, and reserpine 0.3 mg/kg/day; HHR) from the age of 7-25 weeks.

RESULTS

OLETF rats were hypertensive and had microalbuminuria from 9 weeks of age. At 15 weeks, OLETF rats had higher Ang II levels in the kidney, larger glomerular desmin-staining areas (an index of podocyte injury), and lower gene expression of nephrin in juxtamedullary glomeruli, than nondiabetic Long-Evans Tokushima Otsuka (LETO) rats. At 25 weeks, OLETF rats showed overt albuminuria, and higher levels of Ang II in the kidney and larger glomerular desmin-staining areas in superficial and juxtamedullary glomeruli compared to LETO rats. Reductions in mRNA levels of nephrin were also observed in superficial and juxtamedullary glomeruli. Although olmesartan did not affect glucose metabolism, it decreased blood pressure and prevented the renal changes in OLETF rats. HHR treatment also reduced blood pressure, but did not affect the renal parameters.

CONCLUSIONS

This study demonstrated that podocyte injury occurs in juxtamedullary glomeruli prior to superficial glomeruli in type 2 diabetic rats with microalbuminuria. Early treatment with an ARB may prevent the onset of albuminuria through its protective effects on juxtamedullary glomerular podocytes.

Angiotensin II shifts insulin signaling into vascular remodeling from glucose metabolism in vascular smooth muscle cells

BACKGROUND

To clarify the role of angiotensin II (Ang II) in insulin-induced arteriosclerosis, we examined the effects of Ang II on insulin-induced mitogen-activated protein (MAP) kinase activation and cellular hypertrophy in rat vascular smooth muscle cells (VSMCs).

METHODS

Phosphorylated MAP kinases were detected with western blot analysis. Cellular hypertrophy and glucose uptake were evaluated from incorporation of [(3)H]-labeled-leucine and -deoxy-D-glucose, respectively. Cell sizes were measured by Coulter counter.

RESULTS

While Ang II (100 nmol/l, 18 h) augmented cellular hypertrophy by insulin (10 nmol/l, 24 h), insulin alone did not affect hypertrophy without Ang II pretreatment. Insulin increased p38MAP kinase and c-Jun N-terminal kinase (JNK) phosphorylation; in the presence of Ang II, p38MAP kinase, and JNK were further activated by insulin. Treatment of a p38MAP kinase inhibitor, SB203580 (10 µmol/l), and a JNK inhibitor, SP600125 (20 µmol/l), abrogated the [(3)H]-leucine incorporation by insulin in the presence of Ang II. Both the Ang II receptor blocker, RNH-6270 (100 nmol/l), and an antioxidant, ebselen (40 µmol/l), inhibited vascular cell hypertrophy. Specific depletion of insulin receptor substrate-1 with small interfering RNA increased [(3)H]-leucine incorporation by insulin (10 nmol/l, 24 h); pretreatment with Ang II attenuated insulin (10 nmol/l, 30 min)-induced glucose uptake.

CONCLUSIONS

Ang II attenuates insulin-stimulated glucose uptake and enhances vascular cell hypertrophy via oxidative stress- and MAP kinase-mediated pathways in VSMCs. Ang II may also cause insulin signaling to diverge from glucose metabolism into vascular remodeling, affecting insulin-induced arteriosclerosis in hypertension.

Aldosterone Suppresses Insulin Signaling Via the Downregulation of Insulin Receptor Substrate-1 in Vascular Smooth Muscle Cells

Clinical reports indicate that patients with primary aldosteronism commonly have impaired glucose tolerance; however, the relationship between aldosterone and insulin signaling pathway has not been clarified. In this study, we examined the effects of aldosterone treatment on insulin receptor substrate-1 expression and insulin signaling pathway including Akt phosphorylation and glucose uptake in rat vascular smooth muscle cells. Insulin receptor substrate-1 protein expression and Akt phosphorylation were determined by Western blot analysis with anti-insulin receptor substrate-1 and phosphorylated-Akt antibodies, respectively. Glucose metabolism was evaluated using (3)H-labeled 2-deoxy-d-glucose uptake. Aldosterone (1-100 nmol/L) dose-dependently decreased insulin receptor substrate-1 protein expression with a peak at 18 hours (n=4). Aldosterone-induced degradation of insulin receptor substrate-1 was markedly attenuated by treatment with the selective mineralocorticoid receptor antagonist eplerenone (10 micromol/L; n=4). Furthermore, degradation was blocked by the Src inhibitor PP1 (20 micromol/L; n=4). Treatment with antioxidants, N-acetylcysteine (10 mmol/L), or ebselen (40 micromol/L) also attenuated aldosterone-induced insulin receptor substrate-1 degradation (n=4). In addition, proteasome inhibitor MG132 (1 micromol/L) prevented insulin receptor substrate-1 degradation (n=4). Aldosterone treatment abolished insulin-induced Akt phosphorylation (100 nmol/L; 5 minutes; n=4). Furthermore, aldosterone pretreatment decreased insulin-stimulated (100 nmol/L; 60 minutes; n=4) glucose uptake by 50%, which was reversed by eplerenone (10 micromol/L; n=4). These data indicate that aldosterone decreases insulin receptor substrate-1 expression via Src and reactive oxygen species stimulation by proteasome-dependent degradation in vascular smooth muscle cells; thus, aldosterone may be involved in the pathogenesis of vascular insulin resistance via oxidative stress.

Interferon-gamma enhances superoxide production in human mesangial cells via the JAK-STAT pathway

Immune reactive cytokines, such as interferon (IFN)-gamma, have multiple effects in glomerulonephritis. Superoxide anions (O(2)(-)), which are associated with the progression of glomerulonephritis, are mainly generated by nicotinamide adenine dinucleotide phosphate (reduced form) NAD(P)H oxidases. We determined the effects of IFN-gamma on O(2)(-) production, phosphorylation of signal transducer and activator of transcription (STAT)-1alpha, and the mRNA and protein expressions of p22phox and Nox1, components of NAD(P)H oxidases, in human mesangial cells (HMCs). Significant increases in O(2)(-) production with IFN-gamma were completely abolished by the flavin-containing enzyme inhibitor, diphenyleneiodonium (10 micromol/l), and the Janus-activated kinase (JAK)2 inhibitor, AG490 (100 micromol/l). Phosphorylated STAT-1alpha was detected after 5 min of IFN-gamma stimulation using Western blot analysis, and binding to the gamma-activating site was observed from 30 min to 4 h, thereafter by electrophoretic mobility shift assay (EMSA). Super-shift analysis in EMSA revealed that the main transcription factor was STAT-1alpha. IFN-gamma significantly increased the expression of p22phox mRNA and protein, although expression was inhibited by AG490. These data suggest that IFN-gamma stimulates O(2)(-) production in HMCs via the JAK-STAT pathway and NAD(P)H oxidase.

Wetting characteristics and blood clotting on surfaces of copoly(gamma-Benzyl-L-glutamate, gamma-hydroxyethyl-L-glutamine)

The film surface of poly(gamma-benzyl-L-glutamate) (PBLG) was modified with 2-aminoethanol to enhance its hydrophilicity. Controlling the reaction conditions of PBLG and 2-aminoethanol, various types of copoly(gamma-benzyl-L-glutamate, gamma-hydroxyethyl-L-glutamine) film surfaces were obtained. Surface free energy (gamma sv), the dispersive component of gamma sv (gamma dsv), the nondispersive component of gamma sv (gamma psv), and the interfacial free energy of polymer surface with water (gamma sw), which were obtained by using the contact angle measurement and calculation method proposed by Andrade et al., were changed remarkably by the aminolysis. The gamma sv value increased after 2 h of aminolysis from 48.2 (PBLG) to 65.3 dyn/cm and gradually increased to around 70 dyn/cm after 12 h reaction. (gamma dsv) and (gamma psv) changed from 31.0 and 17.2 dyn/cm (PBLG) to 26.5 and 44.3 dyn/cm, respectively. These parameters of the material surfaces, modified over 12 h reaction, were found to be similar to those of the surfaces of canine aorta, vein, and human fibrin membrane. Blood clotting times on these polymer surfaces were comparatively longer than on siliconized glass surfaces.

Wetting characteristics and blood clotting on surfaces of acylated chitins

Various acylated chitins, including formyl, acetyl, propionyl, butyryl, caproyl, capryl, lauroyl, and benzoylchitin, were evaluated as materials for blood contact surfaces by means of contact angle and blood-clotting time measurements. Critical surface tensions of acylated chitins varied within the range of 20-30 dyn cm-1 and were dependent on the length of the acyl side chains. Furthermore, the dispersion and nondispersion components of the surface tension show remarkable differences which are dependent on the type of acyl group attached to chitin. The chitin derivative with 2.0 acetyl groups per N-acetylglucosamine residue gave values of the dispersive and nondispersive components of the surface tension that are very close to those obtained for glutaraldehyde-treated umbilical cord vessels. All of the acylated chitin surfaces show longer clotting times than the original chitin surface.