Search

Oxidative stress can lead to tissue damage in the body, resulting in conditions that may lead to heart failure. Carbonyl proteins and malondialdehyde are common markers for determining oxidative stress. In this study, a high-performance liquid chromatography with ultraviolet‐visible (HPLC-UV-Vis) method was developed for both carbonyl proteins and malondialdehyde and compared with common spectrophotometric methods. The HPLC-UV-Vis method for determining carbonyl proteins showed a linear correlation in a range of 0.05-1.6 µg.mL−1 (correlation coefficient: 0.9939). The limits of detection and quantitation were determined to be 1.7 and 5.1 pmol on-column, respectively. The HPLC-UV-Vis method for malondialdehyde exhibited a linear correlation in the range of 0.04-13.6 µg.mL−1 (correlation coefficient: 0.9982) with limits of detection and quantitation of 1.5 and 4.5 pmol on-column, respectively. As a proof of concept, the applicability of the methods for both marker substances was investigated in chicken heart tissue as a complex matrix sample. To simulate oxidative stress, the tissue was treated with hydrogen peroxide as the oxidizing agent. Samples prepared with hydrogen peroxide showed increased carbonyl protein and malondialdehyde levels when compared to non-oxidized samples and samples treated additionally with the antioxidant Trolox. Regarding oxidative stress, similar results were achieved when compared with common spectrophotometric methods. However, HPLC-UV-Vis presented higher reproducibility and accuracy. The developed methods for both markers enable rapid and simple investigation of possible antioxidant effects on tissue samples. [ABSTRACT FROM AUTHOR]

A fast and simple HPLC method has been developed and validated for the quantification of a completely new anti-cancer drug during the manufacturing process. The combination of four compounds including α-ketoglutaric acid, hydroxymethylfurfural, N-acetyl--methionine and N-acetyl--selenomethionine, administered intravenously, is still in test phase but has already shown promising results in cancer therapy. HPLC separation was achieved on an RP-18 column with a gradient system. However, the highly different concentrations of the compounds required a variation in the detection wavelength within one run. In order to produce a chromatogram where peaks were comparable on a similar range scale, detection at absorption maxima for the two most concentrated components was avoided. After optimization of the gradient program it was possible to detect all four substances within 14 min in spite of their strongly different chemical structure. The method developed was validated for accuracy, repeatability, reproducibility and robustness in relation to temperature and pH of buffer. Linearity as well as the limit of detection and quantification were determined. This HPLC method was found to be precise, accurate and reproducible and can be easily used for in-line process control during the manufacture of the anti-tumour infusion solution. [ABSTRACT FROM AUTHOR]

In order to assess possible renal mechanisms causing the as yet unexplained side-effects of peripheral edema, weight gain and swollen limbs seen during the chronic administration of opioids in patients, a rat study was designed, mimicking a constant infusion (24 h) of morphine (CAS 57–27–2) using subcutaneous drug delivery device systems. Subcutaneous (s.c.) morphine infusions (0, 10, 30 mg/kg body weight/24 h) have been administered using implantable mini-osmotic pumps with a delivery rate of 10 µl/h. In addition, s.c. implantable inulin/PAH clearance depot systems were used in order to measure renal functions such as glomerular filtration rate (GFR = inulin clearance), renal plasma flow (RPF = PAH clearance), creatinine clearance and urea clearance in the conscious rat. Compared to controls, morphine caused an increase in PAH clearance, creatinine clearance (both dose dependent), urea clearance (higher dose), body weight, and urine potassium concentration (both groups). Urine minute volume was reduced in the 10 mg morphine group, a dose dependent highly significant decrease of urine sodium in the 30 mg morphine group compared to controls and a significant decrease compared to the 10 mg group could be found. Serum sodium was highly significant and food uptake was significantly increased in the 30 mg group compared to controls. The histological examination of kidneys revealed no differences among the various groups. These data indicate a role of the kidney in the induction of peripheral edema during permanent morphine administration. [ABSTRACT FROM AUTHOR]

This study deals with the development of enantioselective flow-through immunosensors for triiodothyronine (T3) and tetraiodothyronine (thyroxine, T4) on the basis of a competitive assay using enantioselective antibodies. The instrumental set-up is based on a simple sequential-injection system equipped with a chemiluminescence detector and an immunoreactor, which consists of a flow-cell packed with immobilized haptens. As haptens, 4-amino-l-phenylalanine (4-amino-l-Phe), 4-amino-d-Phe or l-T3 were used. Antibodies directed against 4-amino-l- or d-Phe or l-T3 were labeled with an acridinium ester. Three different approaches for immobilizing the haptens were investigated including simple adsorption on polystyrene, chemical binding to an activated methacrylate polymer and binding via the biotin–streptavidin binding (BSB) system. The latter approach showed the best results regarding repeatability and sensivity. Using biotinylated l-T3 immobilized onto a streptavidin-derivatized trisacryl support and labeled anti-l-T3 antibodies, a detection limit of 15.5 fmol/ml for l-T3 was obtained. One assay cycle including regeneration takes only about 5 min. This approach was applied to detect l-T3 in plasma samples without any sample pre-treatment. The average recovery from spiked plasma sample was about 93% with a R.S.D. below 5%. [Copyright &y& Elsevier]

8-iso-PGF[sub 2α] and 8-iso-PGE[sub 2] , which are released in vivo by free radical catalyzed peroxidation of arachidonic acid, are equipotent vasoconstrictors in vivo and in vitro. It is assumed that they exert this effect via activation of the thromboxane A[sub 2] (TP) receptor or a TP-receptor-like isoprostane receptor. Increased levels of 8-iso-PGF[sub 2α] have been detected in human cardiovascular diseases. It has been found that polyunsaturated fatty acids (PUFAs) have many beneficial effects in cardiovascular diseases, including antivasoconstrictor actions. Therefore, we investigated the influence of perfusions with eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and dihomo-γ-linolenic acid (DGLA) at final concentrations of 3 and 30 μmol/l on vasoconstriction induced by 8-iso-PGF[sub 2α] , 8-iso-PGE[sub 2] and the thromboxane A[sub 2] mimetic U 46619 in the vasculature of the isolated perfused rabbit ear. Additionally, the effect of indomethacin (final concentration 3 μmol/l) on the effects of the PUFAs was investigated. Our results show that the PUFAs at a concentration of 30 μmol/l caused a significant inhibition of the vasoconstrictions induced by 8-iso-PGF[sub 2α] , 8-iso-PGE[sub 2] and U 46619. Furthermore, it can be assumed that a part of the inhibitory effect of DGLA is due to the effect of a cyclooxygenase product, probably PGE[sub 1] , because indomethacin reduced the inhibitory effect of DGLA.Copyright © 2000 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Copyright of Chemical Monthly / Monatshefte für Chemie is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: As continuous production of free radicals and reactive oxygen species is a normal metabolic process, increased metabolism during exercise/workload should increase free radical generation and oxidative stress. Oxidative stress intensity should then depend on the intensity of metabolic stress effects. Intensity of stress is usually reflected in norepinephrine (NE) levels, which correlate linearly and significantly with changes in blood gases, blood buffer systems, blood electrolytes, blood glucose and lactate [Porta, S., Leitner, G., Heidinger, D., Lang, T., Weiss, U., Smolle, K.H., Hasiba, K., 1997. Magnesium während der Alpinausbildung bringt um 30% bessere Energieverwertung. Magnesium-Bulletin 19(2), 59–61]. Those parameters were used in an open study design to screen 64 subjects for metabolic stress effects along with their antioxidative capacity using both venous and capillary blood. To compare venous and capillary blood, we took venous blood samples from 12 healthy volunteers and capillary blood from 52 other healthy subjects. To show whether free radical changes indeed go along with metabolic stress effects, we tried to quantify relations between metabolic stress effects and oxidative stress by linear correlations. In conclusion, both venous and capillary blood are suitable for determining at least those parameters of the oxidative state that we used. All significant correlations of peroxidase activity and oxidation lag time (OLT) with pH, bicarbonate (HCO3), base excess (BE) and magnesium (Mg) indicate that free radical production increases with metabolism. Those relationships could help to evaluate the oxidative state more precisely. [Copyright &y& Elsevier]