Artificial Cochlear Sensory Epithelium with Functions of Outer Hair Cells Mimicked Using Feedback Electrical Stimuli.

We report a novel vibration control technique of an artificial auditory cochlear epithelium that mimics the function of outer hair cells in the organ of Corti. The proposed piezoelectric and trapezoidal membrane not only has the acoustic/electric conversion and frequency selectivity of the previous device developed mainly by one of the authors and colleagues, but also has a function to control local vibration according to sound stimuli. Vibration control is achieved by applying local electrical stimuli to patterned electrodes on an epithelium made using micro-electro-mechanical system technology. By choosing appropriate phase differences between sound and electrical stimuli, it is shown that it is possible to both amplify and dampen membrane vibration, realizing better control of the response of the artificial cochlea. To be more specific, amplification and damping are achieved when the phase difference between the membrane vibration by sound stimuli and electrical stimuli is zero and π , respectively. We also demonstrate that the developed control system responds automatically to a change in sound frequency. The proposed technique can be applied to mimic the nonlinear response of the outer hair cells in a cochlea, and to realize a high-quality human auditory system.

Advanced glycation of high-density lipoprotein and the functionality of aldosterone release in type 2 diabetes.

Patients with type 2 diabetes mellitus (DM) exhibit modification of high-density lipoprotein (HDL), which is likely to have an important role in the development of atherosclerotic cardiovascular disease (ASCVD). Excess production of aldosterone (Ald) results in hypertension as well as ASCVD. However, the biological activity of modified HDL in steroidogenesis is not clear. We measured the accumulation of thiobarbituric acid-reactive substances (TBARSs) and Nɛ-(carboxymethyl)lysine (CML) levels (markers of oxidation and glycoxidation, respectively) in isolated HDL from 41 patients with type 2 diabetes mellitus (DM group) and 41 age- and gender-matched patients in a non-DM group. We quantified angiotensin II-sensitized and -nonsensitized Ald release using a validated living adrenocortical cell assay. TBARS levels in isolated HDL were similar between patients in the DM and non-DM groups, whereas the CML content of HDL in the DM group was lower than that in the non-DM group, irrespective of higher blood glucose and hemoglobin A1c levels. There was no difference in the HDL-induced ex vivo Ald release between the groups. Although sustained hyperglycemia was not a determinant of HDL-induced Ald release, the degree of HDL glycoxidation was inversely associated with HDL-induced Ald release (r=-0.40, P<0.001). In conclusion, in vivo advanced glycoxidation of HDL had an inverse effect on HDL-induced Ald release, independent of the prevalence of type 2 DM.

The angiotensin II type 1 receptor-neprilysin inhibitor LCZ696 blocked aldosterone synthesis in a human adrenocortical cell line.

A recent clinical study indicated that an angiotensin II (Ang II) type 1 (AT1) receptor-neprilysin inhibitor (ARNi) designated LCZ696 (sacubitril/valsartan, as combined sodium complex) was superior to enalapril at reducing the risks of death and hospitalization due to heart failure. Therefore, we investigated the possible mechanisms of the beneficial effect of LCZ696, in which the inhibition of neprilysin enhances atrial natriuretic peptide (NP) or brain NP (ANP or BNP)-evoked signals that can block Ang II/AT1 receptor-induced aldosterone (Ald) synthesis in human adrenocortical cells. The binding affinity of valsartan+LBQ657 (active moiety of sacubitril) to the AT1 receptor was greater than that of valsartan alone in an AT1 receptor-expressing human embryonic kidney cell-based assay. There was no difference in the dissociation from the AT1 receptor between valsartan+LBQ657 and valsartan alone. In Ang II-sensitized human adrenocortical cells, ANP or BNP alone, but not LBQ657 or valsartan alone, significantly decreased Ald synthesis. The level of suppression of Ald synthesis by ANP or BNP with LBQ657 was greater than that by ANP or BNP without LBQ657. The suppression of ANP was blocked by inhibitors of regulator of G-protein signaling proteins and cyclic GMP-dependent protein kinase. The inhibition of neprilysin did not change the mRNA levels of the AT1 receptor, ANP receptor A, regulator of G-protein signaling protein, renin or 3ß-hydroxysteroid dehydrogenases. In conclusion, the inhibition of neprilysin by LBQ657 enhances the NP-evoked signals that can block Ang II/AT1 receptor-induced Ald synthesis in human adrenocortical cells.

Comparison of aldosterone synthesis in adrenal cells, effect of various AT1 receptor blockers with or without atrial natriuretic peptide.

Bifunctional angiotensin II (Ang II) type 1 (AT1) receptor blockers (ARBs) that can block the activation of not only AT1 receptor, but also neprilysin, which metabolizes vasoactive peptides including atrial natriuretic peptide (ANP), are currently being developed. However, the usefulness of the inactivation of ANP in addition to the AT1 receptor with regard to aldosterone (Ald) synthesis is not yet clear. We evaluated the inhibitory effects of various ARBs combined with or without ANP on Ang II-induced adrenal Ald synthesis using a human adrenocortical cell line (NCI-H295R). Ang II increased Ald synthesis in a dose- and time-dependent manner. Ald synthesis induced by Ang II was completely blocked by azilsartan, but not PD123319 (AT2 receptor antagonist). CGP42112 AT2 receptor agonist did not affect Ald synthesis. While most ARBs block Ang II-induced Ald synthesis to different extents, azilsartan and olmesartan have similar blocking effects on Ald synthesis. The different effects of ARBs were particularly observed at 10(-7) and 10(-8 )M. ANP attenuated Ang II-induced Ald synthesis, and ANP-mediated attenuation of Ang II-induced Ald synthesis were blocked by inhibitors of G-protein signaling subtype 4 and protein kinase G. ANP (10(-8) and 10(-7 )M) without ARBs inhibited Ald synthesis, and the combination of ANP (10(-7 )M) and ARB (10(-8 )M) had an additive effect with respect to the inhibition of Ald synthesis. In conclusions, ARBs had differential effects on Ang II-induced Ald synthesis, and ANP may help to block Ald synthesis when the dose of ARB is not sufficient to block its secretion.

Ability of the new AT1 receptor blocker azilsartan to block angiotensin II-induced AT1 receptor activation after wash-out.

INTRODUCTION: The recently approved angiotensin II (Ang II) type 1 (AT1) receptor blocker (ARB) azilsartan strongly reduces blood pressure (BP) in patients with hypertension. We previously reported that azilsartan showed unique binding behavior to the AT1 receptor because of its 5-oxo-1,2,4-oxadiazole moiety. However, the ability of azilsartan to block Ang II-dependent AT1 receptor activation is not yet clear. MATERIALS AND METHODS: Azilsartan and a derivative of azilsartan (azilsartan-7H) that lacks a carboxyl group at the benzimidazole ring were used. Ang II-induced inositol phosphate (IP) production and extracellular signal-regulated kinase (ERK) activation were analyzed in a cell-based wash-out assay. RESULTS: Azilsartan, but not azilsartan-7H, completely blocked Ang II-induced IP production and ERK activation. Our previous report demonstrated that azilsartan mainly interacts with Tyr(113), Lys(199), and Gln(257) in the AT1 receptor. The interactions between azilsartan and Tyr(113) and Gln(257), but not Lys(199), were critical for blocking Ang II-induced IP production and ERK activation after wash-out. CONCLUSIONS: Although our findings regarding the molecule-specific effects of azilsartan are based on basic research, they may lead to an exciting insight into the mechanism of azilsartan.

Extensive atrophic gastritis linked to increased levels of intraluminal hydrogen gas.

BACKGROUND/AIMS: Gastric acid plays an important part in the prevention of bacterial colonization of the gastrointestinal tract. If these bacteria have an ability of hydrogen (H2) fermentation, intraluminal H2 gas might be detected. We attempted to measure the intraluminal H2 concentrations to determine the bacterial overgrowth in the gastrointestinal tract. METHODOLOGY: Studies were performed in 647 consecutive patients undergoing upper endoscopy. At the time of endoscopic examination, we intubated the stomach and the descending part of the duodenum without inflation by air, and 20 ml of intraluminal gas samples of both sites was collected through the biopsy channel. Intraluminal H2 concentrations were measured by gas chromatography. RESULTS: Over all, intragastric and intraduodenal H2 gas was detected in 566 (87.5%) and 524 (81.0%), respectively. The mean values of intragastric and intraduodenal H2 gas were 8.5 +/- 15.9 and 13.2 +/- 58.0 ppm, respectively. The intraduodenal H2 level was increased with the progression of atrophic gastritis, whereas the intragastric H2 level was the highest in patients without atrophic gastritis. CONCLUSIONS: The intraduodenal hydrogen levels were increased with the progression of atrophic gastritis. It is likely that the influence of hypochlorhydria on bacterial overgrowth in the proximal small intestine is more pronounced, compared to that in the stomach.

Extensive atrophic gastritis increases intraduodenal hydrogen gas.

OBJECTIVE: Gastric acid plays an important part in the prevention of bacterial colonization of the gastrointestinal tract. If these bacteria have an ability of hydrogen (H2) fermentation, intraluminal H2 gas might be detected. We attempted to measure the intraluminal H2 concentrations to determine the bacterial overgrowth in the gastrointestinal tract. PATIENTS AND METHODS: Studies were performed in 647 consecutive patients undergoing upper endoscopy. At the time of endoscopic examination, we intubated the stomach and the descending part of the duodenum without inflation by air, and 20 mL of intraluminal gas samples of both sites was collected through the biopsy channel. Intraluminal H2 concentrations were measured by gas chromatography. RESULTS: Intragastric and intraduodenal H2 gas was detected in 566 (87.5%) and 524 (81.0%) patients, respectively. The mean values of intragastric and intraduodenal H2 gas were 8.5 +/- 15.9 and 13.2 +/- 58.0 ppm, respectively. The intraduodenal H2 level was increased with the progression of atrophic gastritis, whereas the intragastric H2 level was the highest in patients without atrophic gastritis. CONCLUSIONS: The intraduodenal hydrogen levels were increased with the progression of atrophic gastritis. It is likely that the influence of hypochlorhydria on bacterial overgrowth in the proximal small intestine is more pronounced, compared to that in the stomach.

High prevalence of gastroesophageal reflux symptoms in patients with both acute and nonacute cough.

Although there have been many studies that showed a close association between gastroesophageal reflux disease (GERD) symptoms and chronic cough, it has been unknown whether acute cough is also associated with GERD. The aim of this study was to evaluate the relationship between GERD and respiratory symptoms in general practice. 1725 consecutive patients who first attended our hospital were enrolled in the present study. They were asked to respond the F-scale questionnaire regardless of their chief complaints. Over all, 656 (38%) patients were diagnosed as GERD and 226 (13%) had respiratory symptoms. Patients with respiratory symptoms had GERD symptoms more frequently than patients without respiratory symptoms (p < 0.05). Forty-three (37%) of 115 patients with acute cough and 48 (43%) of 111 with nonacute cough had GERD symptoms, suggesting that development of GERD is not associated with the period of respiratory symptoms. Patients with respiratory symptoms are at a significantly increased risk of developing GERD. Whether or not treatment for GERD or respiratory diseases is useful for the prevention of respiratory symptoms and GERD, respectively, should not be driving management decisions in primary care.

Nizatidine Improves Impaired Salivary Secretion in GERD.

UNLABELLED: During esophageal acid clearance, salivation plays an important role in defending the esophageal mucosa. Nizatidine, a histamine H2 receptor antagonist, inhibits acetylcholine esterase, with a resultant increase in acetylcholine. We experienced a patient with gastroesophageal reflux disease (GERD) and impaired salivary secretion who has been successfully treated with nizatidine. CASE REPORT: A 63-year-old female visited our hospital with complaints of heartburn and continuous laryngeal discomfort. Saliva scintigraphy was performed to evaluate the salivary function. Washout ratio was decreased to be 25%-40% in individual salivary gland. After the treatment with nizatidine, salivary scintigraphy demonstrated the increased washout ratios. The values of both parotid glands increased up to 90%, whereas those of submandibular glands improved to be around a normal range. GERD symptoms disappeared completely after treatment. In conclusion, nizatidine may be one of therapeutic options for low salivary excretion.

Efficient transfection of primarily cultured porcine embryonic fibroblasts using the Amaxa Nucleofection system.

Porcine embryonic fibroblasts (PEF) are important as donor cells for nuclear transfer for generation of genetically modified pigs. In this study, we determined an optimal protocol for transfection of PEF with the Amaxa Nucleofection system, which directly transfers DNA into the nucleus of cells, and compared its efficiency with conventional lipofection and electroporation. Cell survival and transfection efficiency were assessed using dye-exclusion assay and a green fluorescent protein (GFP) reporter construct, respectively. Our optimized nucleofection parameters yielded survival rates above 60%. Under these conditions, FACS analysis demonstrated that 79% of surviving cells exhibited transgene expression 48 h after nucleofection when program U23 was used. This efficiency was higher than that of transfection of PEFs with electroporation (ca. 3-53%) or lipofection (ca. 3-8%). Transfected cells could be expanded as stably transgene-expressing clones over a month. When porcine nuclear transfer (NT) was performed using stable transformant expressing GFP as a donor cell, 5-6% of reconstituted embryos developed to blastocysts, from which 30-50% of embryos exhibited NT-embryo-derived green fluorescence. Under the conditions evaluated, nucleofection exhibited higher efficiency than conventional electroporation and lipofection, and may be a useful alternative for generation of genetically engineered pigs through nuclear transfer.