Identification of peptide sequences that selectively bind to pentaerythritol trinitrate hemisuccinate-a surrogate of PETN, via phage display technology.

The present research investigates the identification of amino acid sequences that selectively bind to a pentaerythritol tetranitrate (PETN) explosive surrogate. Through the use of a phage display technique and enzyme-linked immunosorbent assays (ELISA), a peptide library was tested against pentaerythritol trinitrate hemisuccinate (PETNH), a surrogate of PETN, to screen for those with amino acids having affinity toward the explosive. The results suggest that the library contains peptides selective to PETNH. Following three rounds of panning, clones were picked and tested for specificity toward PETNH. ELISA results from these samples show that each phage clone has some level of selectivity for binding to PETNH. The peptides from these clones have been sequenced and shown to contain certain common amino acid segments among them. This work represents a technological platform for identifying amino-acid sequences selective toward any bio-chem analyte of interest.

Differential effects of organic nitrates on endothelial progenitor cells are determined by oxidative stress.

OBJECTIVE: Reduced levels and impaired function of endothelial progenitor cells (EPCs) foster development and progression of atherosclerotic lesions. Endothelial nitric oxide synthase (eNOS)-derived NO regulates EPC mobilization and function. Organic nitrates release NO, and therefore may favorably affect EPC biology. METHODS AND RESULTS: We compared the effects of 2 different nitrates on circulating EPC numbers and function. Treatment of rats with pentaerythritol-trinitrate (PETriN) or isosorbide dinitrate (ISDN) increased circulating EPC levels. EPC from ISDN- but not PETriN-treated animals displayed impaired migratory capacity and increased reactive oxygen species formation in EPCs. In vitro treatment with ISDN reduced migration and incorporation of human EPCs into vascular structures on matrigel, whereas PETriN improved EPC function. ISDN, but not PETriN, increased NADPH oxidase-mediated oxidative stress in cultured human EPCs. Addition of polyethylene-glycolated superoxide dismutase or diphenyliodonium normalized both ISDN-induced superoxide anion production and impaired migratory capacity of EPCs. CONCLUSIONS: Long-acting nitrates increase levels of circulating EPCs, but differ in their effects on EPC function dependent on the induction of intracellular oxidative stress. Organic nitrates that improve EPC function may confer long-term cardiovascular protection based on their beneficial effects on EPC biology.

[Silica-containing urinary stones--clinical issues to keep in mind]. / Silikathaltige Harnsteine im Klinikalltag. Was gibt es zu beachten?

Formation of calculi in efferent urinary passages is always due to supersaturation of urinary calculi substances and associated increased crystallization. Apart from the typical calculi, consisting of calcium oxalate, inorganic phosphates, uric acid or cystine, there are occasional signs of rare substance classes. Although more than 50 silicate stones have already been reported internationally, this stone entity remains relatively unknown. In particular, the occurrence of silicate stones in the absence of magnesium trisilicate abuse is extremely rare. A medium-sized left-sided ureterolith was removed from a 54-year-old male patient using a ureteroscope. X-ray diffraction showed it to be a compound stone consisting of 40% silicate. The patient, who in 1986 was living close to the nuclear reactor accident in Chernobyl, showed no signs of a constant uptake of magnesium trisilicate. However, he had undergone partial (2/3) gastrectomy 4 months before for a drug-refractory gastric ulcer, which had been diagnosed at the end of the 1980s and treated with excessive dosages of a magnesium trisilicate antacid preparation until the time of the operation. The patient had also been suffering from unstable angina pectoris since 1986 and treated with Pentalong (pentaerythrityltetranitrate) for 17 years. We were also able to detect silicium dioxide in components of this drug using X-ray diffraction. Silicate uroliths are extremely rare but they can be clearly identified by X-ray diffraction or infrared spectroscopy and distinguished from artifacts or quartz pebbles. Formation of calculi can be prevented by increasing diuresis as well as switching to a different drug and reducing the dosage.

[Quantitative gas chromatography-mass spectrometry determination of pentaerythrityl tetranitrate metabolites pentaerythrityl trinitrate, pentaerythrityl dinitrate and pentaerythrityl in human plasma]. / Quantitative gaschromatographische/massenspektrometrische Bestimmung der Pentaerithrityltetranitrat-Metaboliten Pentaerithrityltrinitrat, Pentaerithrityldinitrat und Pentaerithritylmononitrat in Humanplasma.

Assay methods based on gas chromatography/mass spectroscopy (GC-MS) may be used to measure PE1N (pentaerithrityl mononitrate, CAS 1607-00-7), PE2N (pentaerithrityl dinitrate, CAS 1607-01-8) and intermediate pentaerithrityltrinitrate (PE3N, CAS 1607-17-6) in human plasma. Based on this method a simplified method to quantify the metabolites of PETN (pentaerithrityl tetranitrate, CAS 78-11-5, Pentalong) is described. In the present study a consistent method to extract the metabolites of human plasma and following derivatisation is described. Since PE1N can be quantified up to 150 ng/ml, PE2N and PE3N up to 30 ng/ml in human plasma, a dilution of the plasma samples can be avoided. The mean recovery rate is not so high as in other described methods, and inaccuracy is about 10%. Therefore a calibration range between 0.2-30 ng/ml of PE2N and 1-150 ng/ml of PE1N has to be considered. The described method offers an alternative and applicable option to quantify the PETN-metabolites and elucidate their part as NO-donors.

Effects of nonintermittent treatment of rabbits with pentaerythritol tetranitrate on vascular reactivity and superoxide production.

Pentaerythritol tetranitrate is an organic nitrate ester that undergoes metabolization to pentaerythritol, pentaerythritol trinitrate, pentaerythritol dinitrate and pentaerythritol mononitrate. Recent data suggested that pentaerythritol tetranitrate is endowed with vasoprotective activities in experimental atherosclerosis. This study was undertaken to gain insight into the underlying mechanism. The basic mechanism of action of all pentaerythritol nitrates was evaluated by measuring liberation of nitric oxide (NO), stimulation of human soluble guanylate cyclase and vasorelaxation in rabbit aorta. A subsequent in vivo study in New Zealand White rabbits was performed to investigate the effects of a 4 months lasting nonintermittent oral treatment with 6 mg pentaerythritol tetranitrate kg(-1) day(-1) on vascular superoxide production, endothelium dependent vasorelaxation and vasorelaxation to pentaerythritol tetranitrate itself. The formation rates of NO from the pentaerythritol nitrates (100 microM, n = 5) in presence of 5 mM cystein were (in nM min(-1)): 62.1 +/- 3.2 (pentaerythritol tetranitrate), 21.3 +/- 0.9 (pentaerythritol trinitrate), 6.4 +/- 0.6 (pentaerythritol dinitrate) and 3.2 +/- 0.4 (pentaerythritol mononitrate). Similarly, the pD2 values (-log M) for half-maximal activation of soluble guanylate cyclase decreased from pentaerythritol tetranitrate (3.391 +/- 0.09, n = 4) to pentaerythritol mononitrate (2.655 +/- 0.04, n = 3) as did the pD2 values (in -log M) for half-maximal relaxation of rabbit aortic rings (n = 7) from pentaerythritol tetranitrate (8.3 +/- 0.17) to pentaerythritol mononitrate (5.0 +/- 0.11). Significant correlations were found between the NO formation rates and the pD2 values for enzyme stimulation (r = 0.98, P = 0.002) and vasorelaxation (r = 0.90, P = 0.049) suggesting that these effects of the pentaerythritol nitrates were mediated by NO. The results of the in vivo study showed that aging induces a significant increase of aortic superoxide production (median values, n = 10) from 2.45 nM mg(-1) min(-1) (age 7 months) to 3.39 nM mg(-1) min(-1) (age 11 months, P < 0.01) that was prevented by concurrent treatment with pentaerythritol tetranitrate (2.76 nM mg(-1) min(-1)). In vitro vasorelaxation to pentaerythritol tetranitrate was identical in all groups indicating absence of nitrate tolerance. Endothelium-dependent vasorelaxation was also identical in all groups. These data suggest that oral treatment with pentaerythritol tetranitrate reduces vascular oxidant stress by an NO-dependent pathway, which may contribute to the vasoprotective activity of pentaerythritol tetranitrate in experimental atherosclerosis.

[Long-term effect of various nitrates in ischemic heart disease and latent heart failure]. / Untersuchungen zum Langzeiteffekt verschiedener Nitrate bei ischämischer Herzkrankheit und latenter Herzinsuffizienz.

In 24 patients (pts) with proven coronary artery disease, stable angina pectoris (AP) and elevated pulmonary artery pressure (PAP) during bicycle exercise, the acute and chronic (4 and 8 months) effects of several long-acting nitrates in different dosages: 50-300 mg pentaerythrityltetranitrate (PETN) or 40-120 mg isosorbide dinitrate (ISDN) were evaluated in comparison to sublingual nitroglycerin. Nitroglycerin was about 30%-40% more effective than PETN and ISDN with regard to pulmonary artery pressure at exercise. Beneficial effects of both long-acting nitrates were shown with regard to the number of anginal attacks, nitroglycerin consumption, and ST-segment depression both during short- and long-term treatment. Both nitrates decreased exercise pulmonary artery pressure by 15%-20%, at acute testing and during chronic therapy. There was no difference with respect to the long-term effects of both long-acting nitrates. However, more side-effects were observed during ISDN treatment. There were no signs of nitrate tolerance development with the therapy schedules under investigation.