Advanced glycated end-products inhibit dilation through constitutive endothelial RAGE and Nox1/4 in rat isolated skeletal muscle arteries

OBJECTIVE

This study investigated the actions of advanced glycated end-products (AGE), their receptors (RAGE), and NAD(P)H oxidase (Nox) subtypes 1, 2, and 4 on mechanisms of endothelium-dependent dilation of the rat cremaster muscle artery (CMA).

METHODS

Immunofluorescence studies were used to examine expression of RAGE in rat arteries. ROS accumulation was measured using luminescence and fluorescence assays. Functional studies were performed using pressure myography.

RESULTS

High levels of RAGE expression were shown in the endothelial cells of the CMA, compared with low endothelial expression in middle cerebral and mesenteric arteries and the aorta. Exogenous AGE (in vitro glycated bovine serum albumin) stimulated H2O2 accumulation in CMA, which was prevented by the RAGE antagonist FPS-ZM1, the NAD(P)H oxidase (Nox) inhibitor apocynin and inhibited by the Nox1/4 inhibitor setanaxib, but not the Nox2 inhibitor GSK2795039. In functional studies, AGE inhibited vasodilation of CMA stimulated by acetylcholine, sodium nitroprusside, and the BKCa activator NS1619, but not adenosine-induced dilation. FPS-ZM1, apocynin, and setanaxib prevented the inhibitory effects of AGE on responses to acetylcholine and NS-1619.

CONCLUSION

These observations suggest RAGE are constitutively expressed in the endothelium of the rat CMA and may be activated by AGE to stimulate Nox1/4 and ROS formation with resulting inhibition of NO and BKCa-mediated endothelium-dependent dilation.

Advanced glycation end products acutely impair ca(2+) signaling in bovine aortic endothelial cells

Post-translational modification of proteins in diabetes, including formation of advanced glycation end products (AGEs) are believed to contribute to vascular dysfunction and disease. Impaired function of the endothelium is an early indicator of vascular dysfunction in diabetes and as many endothelial cell processes are dependent upon intracellular [Ca²⁺] and Ca²⁺ signaling, the aim of this study was to examine the acute effects of AGEs on Ca²⁺ signaling in bovine aortic endothelial cells (BAEC). Ca²⁺ signaling was studied using the fluorescent indicator dye Fura-2-AM. AGEs were generated by incubating bovine serum albumin with 0–250 mM glucose or glucose-6-phosphate for 0–120 days at 37°C. Under all conditions, the main AGE species generated was carboxymethyl lysine (CML) as assayed using both gas-liquid chromatograph-mass spectroscopy and high-performance liquid chromatography. In Ca²⁺-replete solution, exposure of BAEC to AGEs for 5 min caused an elevation in basal [Ca²⁺] and attenuated the increase in intracellular [Ca²⁺] caused by ATP (100 μM). In the absence of extracellular Ca²⁺, exposure of BAEC to AGEs for 5 min caused an elevation in basal [Ca²⁺] and attenuated subsequent intracellular Ca²⁺ release caused by ATP, thapsigargin (0.1 μM), and ionomycin (3 μM), but AGEs did not affect extracellular Ca²⁺ entry induced by the re-addition of Ca²⁺ to the bathing solution in the presence of any of these agents. The anti-oxidant α-lipoic acid (2 μM) and NAD(P)H oxidase inhibitors apocynin (500 μM) and diphenyleneiodonium (1 μM) abolished these effects of AGEs on BAECs, as did the IP₃ receptor antagonist xestospongin C (1 μM). In summary, AGEs caused an acute depletion of Ca²⁺ from the intracellular store in BAECs, such that the Ca²⁺ signal stimulated by the subsequent application other agents acting upon this store is reduced. The mechanism may involve generation of reactive oxygen species from NAD(P)H oxidase and possible activation of the IP₃ receptor.

[Ebstein's anomaly with patent foramen ovale and supraventricular paroxysmal tachycardia]

A case of asymptomatic 36 years old men with Ebstein anomaly of tricuspid valve, patent foramen ovale and paroxismal supraventricular tachycardia is presented in this paper. A routine physical examination revealed a heart systolic murmur along left and right side of sternum, with right bundle branch block on ECG. It led to the detailed non-invasive cardiologic examination (transthoracic, transeophageal and stress echocardiography, ambulatory ECG), what disclosed above mentioned Ebstein anomaly. Also he was operated on upon superior lip fissure at the first year of life. Regarding his very mild symptoms (NYHA g. 1), he was treated only medicamentosly.

[Congenital heart defects: single ventricle with pulmonary valve stenosis and malposition of the great blood vessels]

A case of two: 21 years and 39 years old male patients with congenital heart disease: Single Ventricle with pulmonary valve stenosis and L-malposition of the great vessels. In the first case the diagnosis of congenital pulmonic stenosis & tricuspid regurgitation was established after birth and during the previous period. In the second case the diagnosis of VSD was established during the recruiting checkup, when he was 18 years old. Detailed non-invasive cardiologic examination was performed (transthoracic & transoesophageal echocardiography) and the diagnosis of Single Ventricle with pulmonary valve stenosis & L-malposition of the great vessels: Double-Inlet Left Ventricle with severe symptoms (21 years old & supraventricular paroxysmal tachycardia) with middle symptoms (39 years old) were established in both cases.

Use of short-term culture for identification of Mycobacterium avium subsp. paratuberculosis in tissue from Crohn's disease patients

OBJECTIVE

To investigate the role of Mycobacterium avium subsp. paratuberculosis (MAP) in Crohn's disease (CD), using short-term mycobacterial culture media.

METHODS

Sixty-three tissue specimens from 27 CD patients and 36 controls were processed and inoculated into a modified 7H9 broth base medium and incubated at 37 degrees C and 5% CO2 for up to 1 year. Acid-fast staining, determination of mycobactin dependency, PCR analysis using two IS900-derived oligonucleotides and hybridization with an internal probe were performed.

RESULTS

MAP was present in six of seven (86%) surgically resected tissue samples and in four of 20 (20%) biopsies, with an overall 37% from CD patients, as compared to two of 36 (5.6%) of control specimens. The presence of MAP in Mycobacterial Growth Indicator Tube (MGIT) cultures was detected within 10-12 weeks for surgically resected tissue and after 40 weeks for biopsy specimens, with no MAP growth detected in 12B* Bactec cultures.

CONCLUSIONS

Because MAP was present in 86% of resected tissue compared to 20% of biopsy specimens from CD patients, we speculate that MAP resides in the submucosal layer closer to the active part of the ulcer rather than on the surface of the mucosal cells. Thus, surgically resected tissue cultured in MGIT medium is a favorable protocol for rapid cultivation of MAP and for investigating its role in CD pathogenesis. The data support the mycobacterial role in CD pathogenesis.

Occurrence of the IS900 gene in Mycobacterium avium complex derived from HIV patients

The occurrence of the insertion sequence IS900 in Mycobacterium avium subsp. avium strains isolated from HIV infected patients has been investigated. In this study, genomic DNA from 62 mycobacterial isolates [31 strains of M. avium complex (MAC) consisting of 26 M. avium subsp. avium HIV-isolates and five non-HIV isolates and 31 additional Mycobacterium species] were analysed by an IS900 -based polymerase chain reaction (PCR) assay and Southern hybridization using a non-radioactive-labelled 251 bp DNA fragment located at the 5'-region of the IS900 sequence. As expected, none of the 28 Mycobacterium species contained the IS900 in their genomic DNA. Of the 26 M. avium subsp. avium HIV-isolates, 15 (57.6%) were strongly positive for the IS900 or IS900 related sequence. The five pulmonary non-HIV MAC isolates were negative for the IS900. As expected, the three strains of M. avium subsp. paratuberculosis were positive. This PCR guided study suggest that the IS900 gene is very common in clinical strains of M. avium subsp. avium especially those isolated from HIV patients. Ultimately the IS900 PCR-based assay may provide a useful tool for diagnostic and epidemiological studies related to MAC infections in HIV patients.

Organic-phase biosensing of secondary alcohols with a Ta. brockii alcohol dehydrogenase electrode

An organic-phase enzyme electrode for monitoring secondary alcohols is described. The new biosensor relies on the biocatalytic activity of Ta. brockii alcohol dehydrogenase in non-aqueous media. The Eastman-AQ 55D polymeric coating, known for its stability in organic solvents, is used to entrap the enzyme and its NADP+ cofactor onto the glassy carbon surface. Various experimental variables, influencing the response of the reagentless sensor, are explored for optimum performance. The solvent-induced changes in the enzymatic activity result in an extended linear range. The work expands the scope of organic-phase biosensors towards additional substrates of analytical significance.