High-pressure Liquid Chromatography Hplc Research Articles

English

Toxicity of the freeze-dried micro-aquatic planktonic cyanobacterium Oscillatoria agardhii, dominating and isolated from Makkah –KSA was studied. Microcystins were detected from freeze-dried cells using high pressure liquid chromatography HPLC. The histopathological examination of mice liver injected on week basis with diluted 1/5 of the lethal dose, (105 mg/ Kg body weight), of toxin extract revealed sever changes in liver histology and displayed apparent signs of degenerative hepatic structure. Cytoplasmic vacuolation and parenchyma exhibit hepatocytes degeneration. Hepatic vasculature and biliary system were blocked and severely damaged. The effect of the extract on blood contents and liver function of white mice was investigated. Mice were divided into three groups and injected intraperitoneally (i.p) with weekly reciprocal doses of toxin extract as 21, 42 and 63 mg/ mice, respectively, for seven weeks. Mice injected with 63 mg were the mostly affected and showed signs of acute cellular and physiological damage involving oligocythemia, leucoytosis, marked increase in serum urea, cholesterol, triglycerides, creatinine, Aspartate Aminotransferase (AST), alanine aminotransferase (ALT), hematocrit (HCT) and mean cell hemoglobin concentration (MCHC), while blood platelets showed abnormal increase which suggest an inhibitory action on haemopiesis. In addition, the abnormal pathophysiology observed here reflects the sever toxic effect from the crude extract of O. agardhii on both liver and kidney. Key words: Cyanobacterium, blood, histopathology, mice.

Valsartan improves mitochondrial function in hearts submitted to acute ischemia

The effect of valsartan, an angiotensin II-type I receptor blocker, on the mitochondrial function, was studied using an ex vivo animal model (hearts from Wistar rats), perfused in a Langendorff system and then submitted to global acute ischemia. Parameters evaluated were: membrane electrical potential (ΔΨ, using a tetraphenylphosphonium-TPP+-electrode), oxygen consumption by the respiratory chain (Clark-type O2 electrode), phosphorylation lag phase (time necessary to phosphorylate a fixed amount of ADP) and ATP/ADP ratio (adenine nucleotides quantified by high-pressure liquid chromatography—HPLC). Valsartan acts preferentially in the phosphorylation, increasing ATP/ADP ratios (succinate: 1.6±0.4 versus 0.5±0.1—P<0.05; ascorbate/N,N,N′,N′-tetramethyl-P-phenylenodiamine-TMPD: 1.1±0.2 versus 0.4±0.1—p<0.05 versus ischemia in the absence of valsartan) and decreasing lag phase (glutamate/malate: 50.0±9.6 s versus 127.2±19.03 s–84.6±16.2% versus 215.3±32.2%; P=0.01; succinate: 111.8±33.1 s versus 275.73±45.99 s–168.2±49.8% versus 414.9±69.2%; P=0.02 or ascorbate/TMPD: 11.0±3.9 s versus 62.4±11.63 s–34.9±12.4% versus 198.1±36.9%; P=0.001 versus ischemia in the absence of valsartan). This enables a higher energy production in hearts submitted to acute ischemia, for which having energy becomes critical to preserve mitochondrial function. These mechanisms allow us to better understand valsartan cytoprotection in ischemic cardiomyopathy.

2. Sensitized degradation of chlorophenols on iron oxides induced by visible light: Comparison with titanium oxide

The sensitized photocatalytic degradation of mono-, di- and trichlorophenols on iron oxides aqueous suspensions of α-Fe2O3 and α-FeOOH is reported in detail. The degradation of these compounds followed pseudo-first-order kinetics when α-Fe2O3 was used as photocatalyst. α-FeOOH was found to be inactive for chlorophenols degradation with the exception of 2,4-dichlorophenol (2,4-DCP) where a modest effect was observed. The formation of a surface complex by the chlorophenols with the iron oxide and the solubility of the particular chlorophenol in aqueous solution were observed to be the controlling parameters during the photodegradation. The results obtained with the most active catalyst α-Fe2O3 are compared with TiO2. Total mineralization of chlorophenols was observed on TiO2 while on α-Fe2O3 only partial mineralization was observed. In either case, the intermediates produced in solution during the photodegradation were found to be significantly more biodegradable than the initial compound. For mono-, di- and trichlorophenols the overall photocatalytic degradation was observed to increase in the order: 2,4,6-trichlorophenol (2,4,6-TCP)<2,3-dichlorophenol (2,3-DCP)<2-chlorophenol(2-CP)<2,4-DCP. The former sequence shows that the recalcitrant 2,4-DCP degrades more rapidly than other chlorophenols tested during this study. The photodegradation of chlorophenols on α-Fe2O3 and TiO2 proceeds mechanistically through para-hydroxylation of the initial compound as suggested by the intermediates found by high-pressure liquid chromatography HPLC during the course of the degradation.

Condensation nucleation light scattering detection with microbore liquid chromatography for lipid analysis

Methods of analysis for both neutral and phospholipids based on microbore high-pressure liquid chromatography HPLC coupled with detection by condensation nucleation light scattering detection are described. The limits of detection for phospholipids were below 100 ng/mL, corresponding to less than 0.5 ng or less than 1 pmole, but were even lower for neutral lipids, and down to 12 ng/mL (0.06 ng, 0.074 pmole). The method was applied to the determination of lipids in egg yolk samples. © 2000 John Wiley & Sons, Inc. J Micro Sep 12: 204–210, 2000

Condensation nucleation light scattering detection with microbore liquid chromatography for lipid analysis

Methods of analysis for both neutral and phospholipids based on microbore high-pressure liquid chromatography HPLC coupled with detection by condensation nucleation light scattering detection are described. The limits of detection for phospholipids were below 100 ng/mL, corresponding to less than 0.5 ng or less than 1 pmole, but were even lower for neutral lipids, and down to 12 ng/mL (0.06 ng, 0.074 pmole). The method was applied to the determination of lipids in egg yolk samples. © 2000 John Wiley & Sons, Inc. J Micro Sep 12: 204–210, 2000

Kinetics and mechanism of the nucleophilic exchange reaction of iodide‐131 with 15‐(para‐iodo‐phenyl) pentadecanoic acid

A procedure for labelling p-IPPA with 131 I by iodine isotope exchange in ethanol using benzoic acid was described. The method results in an overall radiochemical yield of more than 80 % within 50 min. at 170°C. The specific activity of the final product was 10 mCi/mg. The reaction conditions were investigated using Cu(I) in acetic acid, pivalic acid, ammonium acetate and ammonium sulfate. The activation energy of the reaction was calculated to be E= 33.54 Kcal/mol. Quality control of the product was performed by means of high pressure liquid chromatography HPLC.

Persistence of 7-(2-hydroxyethyl) guanine-DNA adducts in rats exposed to ethene by inhalation

Quantification of 7 2 hydroxyethyl guanine 7 HEG adduct in DNA of livers and lymphocytes of male Sprague-Dawley rats exposed to 300 ppm ethene by inhalation 12 h a day for three consecutive days was performed to evaluate the potential of ethene to produce DNA adducts in these tissues. The persistence of 7 HEG in livers and lymphocytes was studied in rats sacrificed 0, 1, 5, and 20 days after the last exposure. DNA samples from control and treated animals were analysed for 7 HEG and 7 methylguanine 7 MG adducts by thin layer chromatography TLC combined with a high pressure liquid chromatography HPLC assay. After a 3 day exposure to ethene, 7 HEG accumulated to a similar extent in liver and lymphocytes, with the mean adduct level of 7.0 0.7 adducts per 107 nucleotides in liver and 7.4 0.7 adducts per 107 nucleotides in lymphocytes of rats sacrificed immediately after cessation of exposure. The approximate half life of 7 HEG was 5 days in liver and 3 days in lymphocytes, which is consistent with the loss of adduct primarily by spontaneous depurination. In addition, the background levels of 7 HEG and 7 MG were determined in the liver and lymphocytes from the control rats.

Platelet synthesis of cyclooxygenase and lipoxygenase products in type I and type II diabetes

In 24 type I and 22 type II diabetic patients without vascular complications and in 25 controls platelet thromboxane A2 (TxA2) and prostaglandin E2 (PGE 2) production (by radioimmunoassay-RIA) and 1–14C arachidonic acid (AA) metabolism (by high pressure liquid chromatography-HPLC) after thrombin stimulation were studied. Platelets both from type I and type II diabetics generated larger amounts of TxB2 (p < 0.001) and PGE 2 (p<0.005) than controls, independently of the presence of retinopathy. No significant differences in platelet AA uptake or metabolism via the cyclooxygenase (CO) route, after thrombin stimulation (5 NIH U/ml), were observed in diabetic patients: lipoxygenase metabolites were found to be slightly, but significantly decreased. A positive linear relationship (r=0.64, p < 0.001) was found between HbA-1c and TxB2 production, but not with fasting plasma glucose. These results indicate that metabolic alterations can affect platelet function independently of vascular complications. The absence of alterations in intraplatelet 1–14C AA metabolism via CO, in the presence of increased TxB2 and PGE 2 production from endogenous AA, suggests that the activation of CO is not the only possible mechanism of platelet activation and that probably an increased availability of platelet AA plays an important role in the enhanced platelet aggregation commonly found in diabetics.