Highly selective and sensitive determination of free and total amino acids in Apocynum venetum L. (Luobuma tea) by a developed HPLC–FLD method coupled with pre-column fluorescent labelling

Amino acids (AA) are important chemical constituents of tea leaves remarkably influencing the quality of tea. In this study, free AA and total AA in Apocynum venetum L. (Luobuma tea) were estimated by HPLC equipped with fluorescent detector using 2-[2-(7H-dibenzo[a,g]carbazol-7-yl)-ethoxy] ethyl chloroformate (DBCEEC) as a fluorescent labelling reagent. Different parameters for derivatization and separation were optimized. AA were rapidly derivatized within 3 min at room temperature with DBCEEC. In conjunction with a gradient elution, a baseline resolution of 20 analytes was achieved on a reversed-phase Hypersil BDS C18 column. LC separation for the derivatized AA showed good reproducibility. Twenty AA were detected and showed significant linear responses with correlation coefficients (>0.9992). This developed method offered the low detection limit of 2.88–23.4 fmol.     

Current Strategies for Atherosclerosis and Lowering Cholesterol

Atherosclerosis is a multifactorial disorder in which nutritional factors are closely related to a number of the manifestations of the disease. Sounder nutritional principles might therefore prevent atherosclerosis itself or its major complications. Optimising nutrients would diminish monocyte adhesion to endothelium, suppress platelet aggregation, prevent oxidative modification of lipoproteins, minimise activation of coagulant factors and reduce the flux of cholesterol and of atherogenic lipoproteins through plasma.

Optimising the mix of dietary fatty acids should have the highest priority. Emphasis should be placed on those fatty acids, such as those derived from fish, which modify several cardiovascular risk factors, including plasma lipids, blood pressure and coagulation factors. Reduction of risk factors is also achieved but to a lesser extent by reducing total fat intake, reducing dietary cholesterol, optimising the mix of starches and fibre and increasing plant foods generally.

A developing strategy is to identify genetic predisposition to environmentally induced hyperlipidaemia, since most forms of hyperlipidaemia reflect interactions between genetic and dietary factors.     

Determination of Fatty Acid Levels in Erythrocyte Membranes of Patients with Chronic Fatigue Syndrome

Abstract

Chronic fatigue syndrome (CFS) is an illness characterized by persistent and relapsing fatigue, often accompanied by numerous symptoms involving various systems of whole body. The etiology of CFS remains unclear. Literature reported whether the concentrations of the essential fatty acids in red cell membranes of CFS patients were decreased is controversial. In our study, Forty-two patients who fulfilled the diagnostic criteria defined by Centers for Disease Control and Prevention (CDC). Thirty-seven age- and sex-matched controls were selected from healthy medical staffs and volunteers. After lipid analysis, we found that the levels of the arachidonic acid (ARA) and docosahexanoic acid (DHA) were decreased in patients suffered from CFS. However, the levels of the palmitic acid and oleic acid were increased. We speculated that there are two possible mechanisms--one of which is that oxidative stress has led to an excessive oxidation and resulting in the above fatty acids. Alternatively, insufficiency of ingestion of fatty acids might not be the major cause.     

Glutamate concentration in whole saliva and taste responses to monosodium glutamate in humans

Abstract

It is universally accepted that saliva plays an important role in taste sensations. However, interactions between constituents of whole saliva and the five basic taste modalities are still poorly understood. The aim of the present study was to evaluate possible relationship between endogenous glutamate (Glu) levels in whole saliva and taste responses to a prototypic umami substance, monosodium glutamate (MSG; 0.03–10.0%). Rated intensity and pleasantness of MSG taste was studied in healthy volunteers divided into a high glutamate (HG) in saliva (HG; n = 19) and low glutamate in saliva (LG; n = 18) group based on the median split level of salivary Glu. The HG and LG group did not differ in terms of electrogustometric thresholds, rated intensity of the MSG samples and pleasantness of distilled water and the lower MSG concentrations (0.03–1.0%). Perceived intensity of water taste was significantly ( P     

Biomarkers of toluene exposure in rats: mercapturic acids versus traditional indicators (urinary hippuric acid and o-cresol and blood toluene)

Abstract

1. Toluene (TOL) is a neurotoxic, ototoxic and reprotoxic solvent which is metabolized via the glutathione pathway, producing benzylmercapturic, o-, m- and p-toluylmercapturic acids (MAs). These metabolites could be useful as biomarkers of TOL exposure.

2. The aims of this study were (1) to provide data on MAs excretion in rat urine following TOL exposure by inhalation, (2) to compare them to data from traditional TOL biomarkers, i.e. TOL in blood (Tol-B), and urinary hippuric acid (HA) and o-cresol (oCre) and (3) to establish a relationship between these different indicators and the airborne TOL concentration (Tol-A).

3. Sprague–Dawley rats were exposed to a range of TOL concentrations. Blood and urine were collected and analyzed to determine biomarker levels.

4. Levels of the four MAs correlate strongly with Tol-A (comparable to the correlation with Tol-B).

5. MAs are thus clearly superior to oCre and HA as potential markers of exposure to TOL.     

Effect of vancomycin on the cytoplasmic membrane fatty acid profile of vancomycin-resistant and -susceptible isolates of Staphylococcus aureus

This study was designed to analyze the effect of vancomycin on the cytoplasmic membrane fatty acid (FA) composition of vancomycin-resistant Staphylococcus aureus (VRSA), vancomycin-intermediate resistant S. aureus (VISA), and vancomycin-susceptible S. aureus. One low-level vancomycin-resistant isolate (LLR-VRSA) termed CP2, along with two vancomycin intermediate-resistant S. aureus isolates (VISA-CP1) and Mu50 (ATCC #700699), were studied. The LLR-VRSA isolate CP2, recovered from the blood sample of a postoperative cardiac patient, exhibited vanA type vancomycin resistance [minimum inhibitory concentration (MIC) 16 μg/ml], and the vanA cassette was located on a plasmid. CP1, isolated from the pus sample of the same patient, exhibited vancomycin intermediate resistance (MIC 8 μg/ml) in the absence of the vanA, vanB, or vanC gene. As susceptible controls, we used PSA (vancomycin MIC 2 μg/ml), which was isolated from the pus sample of a neonate, and S. aureus (ATCC# 29213). Membrane FA analysis was carried out using gas chromatography coupled with mass spectrometry. For this purpose, CP1, CP2, Mu50, and the susceptible control isolates were grown in the presence and absence of vancomycin. Comparative analysis showed an increase in the relative proportion of unsaturated FAs during growth under vancomycin stress. The isolate CP2 (LLR-VRSA) exhibited a higher MIC to vancomycin than the other isolates used in present study (16 μg/ml) and under vancomycin stress conditions, quantitatively, it showed a high rate of conversion of saturated to unsaturated membrane FAs than CP1, Mu50 (VISA isolate) and the susceptible control PSA. The rate of saturated-to-unsaturated FA conversion increased as the concentration of vancomycin in the growth media was increased. Therefore, it is concluded that S. aureus tend to modify their membrane lipid chemistry from saturated to unsaturated in order to survive in a vancomycin stress environment.     

Combinations of ezetimibe with nonstatin drug regimens affecting lipid metabolism

In this article we discuss the available data on the effects of combined therapy of ezetimibe with agents affecting lipid metabolism other than statins. We consider studies evaluating the effects of combined therapy of ezetimibe with bile acid sequestrants, fenofibrate, niacin, n-3 fatty acids, plant sterols, orlistat, metformin, acarbose and glitazones. Combination of ezetimibe with bile acid sequestrants (especially colesevelam) was shown to have additional effects on lipid parameters in patients with hyperlipidemia. Combination of ezetimibe with fenofibrate may be a good approach to improve the overall lipid profile of patients with mixed hyperlipidemia. The addition of ezetimibe to niacin-based therapy can be useful for high-risk patients with dyslipidemia who are not achieving their assigned treatment goals. For patients who cannot tolerate statins there are useful combinations of ezetimibe with other drugs affecting lipid metabolism. These combinations improve many metabolic parameters, but more trials should be carried out to reach more robust conclusions about their effects on cardiovascular disease prevention.