Determination of salicylate in blood serum by flow injection with immobilized salicylate hydroxylase

A flow injection (FI) enzymatic system, based on the use of immobilized salicylate hydroxylase in glass beads, was developed for the determination of salicylate. Salicylate hydroxylase and nicotinamide adenine dinucleotide (NADH) are used to convert salicylate to catechol. The reaction of catechol with 4-aminophenol at high pH yields a colored product which is detected spectrophotometrically at 565 nm. Ten samples of human serum containing from 5.0 x 10(-4) to 5.0 x 10(-3) mol/L added salicylate were analyzed and the recovery was determined. Eight additional serum samples containing salicylate were analyzed by the Trinder test and the proposed method. The results obtained with the 2 methods showed good agreement by the statistical Student's t-test. The relative precision of the method is about 3.4% (RSD of the mean recovery). Considering the lowest concentration analyzed, the quantitative limit of detection is about 0.2 x 10(-5) mol/L (3 x SD). The volume of the sample used was 150 microL. The proposed method was also used to analyze medicines containing acetylsalicylic acid. The results were statistically compared with those obtained through the U.S. Pharmacopoeia procedure and showed excellent agreement.     

Interaction of manganese(II) with methyl salicylate ethyl salicylate and phenyl salicylate

The proton ligand stability constants of methyl salicylate, ethyl salicylate and phenyl salicylate and the stepwise stability constants of manganese(II) complexes with these have been determined potentiometrically in aqueous ethanol system 50/50 (v/v) at 25°C at different ionic strengths, viz. 0.050 M, 0.075 M, 0.100 M and at 35 and 45°C at an ionic strength of 0.05 M. The thermodynamic stability constants of the complexes have been evaluated from the various values by extrapolating to zero ionic strength at 25°C. The thermodynamic parameters such as free energy changes (ΔG), enthalpy changes (ΔH) and entropy changes (ΔS) involved have been calculated.     

The preparation of 5-phenacylisoxazoles and 5-hydroxyphenyl-isoxazoles and -pyrazoles by the condensation of C(a)-dianions with ethyl benzoylacetate and methyl salicylate

C(α), O-Dilithiooximes and C(α), N-Dilithiophenylhydrazones were prepared in an excess of lithium diisopropylamide (LDA). The former was condensed with ethyl benzoylacetate and methyl salicylate, and the latter condensed with methyl salicylate. The resulting precyclization intermediates were then treated with aqueous acid, which was followed by cyclodehydration to give phenacylisoxazoles and hydroxyphenyl-isoxazoles and -pyrazoles.     

Determination of the sodium-to-calcium ratio in femora of normal and diabetic rats by INAA

The Na-to-Ca ratio has been determined in femora of normal rats, untreated diabetic rats and diabetic rats treated with ascorbic acid. The determination was based on short-term activation and counting of the²⁴Na and⁴⁹Ca activities in the relevant photopeaks. The Na-to-Ca ratios were significantly increased in both treated and untreated diabetic animals as compared to intact controls due to increased Na contents in the diabetic rats.     

Inhibition of tumoral graft growth by pretreatment with normal or heat-modified tumoral cells

The intravenous injection of Ehrlich tumour cells (TC) into Swiss mice, or BP8-fibrosarcoma cells into C3H mice, caused no intra-organ dissemination of the tumour but resulted in increasing resistance of animals to these two tumours. The percentage of mice protected against a regularly lethal dose of TC given intraperitoneally (i. p.) increased with the dose and the number of immunizing injections to the i. p. challenge. However, after high or repeated doses a cancerous nodule sometimes developed at the site of intravenous injections (penis vein), which caused death of the animal, not by extension of the tumour but by urethral occlusion.Moderate heating (46, 49,5 or 52°C) of the TC did not impair their immunogenicity but prevented their multiplication in normal mice. It was thus possible, by intradermal injections of heated TC, to protect mice against a dose of intact TC.The efficiency of prophylaxis depended on the temperature to which the cells were exposed (optimal temperature depending on the type of tumour), on the number of injections and on the medium in which the cells were suspended. When Freund's complete adjuvant was used, all mice were protected against tumour ascites following challenge.     

A hydrogel formed by cetylpyrrolidinium bromide and sodium salicylate

A novel hydrogel constructed by N-methyl-N-cetylpyrrolidinium bromide (C₁₆MPBr) and sodium salicylate (NaSal) is investigated using ¹H NMR, FT-IR, SEM, and rheological measurements. Through the rheological characterization of the hydrogels, both the NaSal concentration and pH have significant effects on the formation and properties of the gels. ¹H NMR, FT-IR, and SEM have also been employed to investigate the molecular arrangement and morphology of the gels. Hydrophobic and electrostatic interactions are considered as the main driving forces to form the gels.     

Integrated analysis of serum and liver metabonome in liver transplanted rats by gas chromatography coupled with mass spectrometry

In this paper, we present a metabonomic method for the investigation of abnormal metabolic process in both serum and liver tissue of liver transplanted rats. Syngeneic transplantation was performed on male Lewis rats. The serum and grafted liver on day 1, 3, and 7 post-transplant were collected to analyze endogenous metabolites using gas chromatography coupled with mass spectrometry (GC-MS). The method was validated with acceptable linearity, precision, and repeatability. Thirty-four metabolites in serum and 29 metabolites in liver were identified. Results of correlation analysis illustrated metabolites with similar function exhibited similar variations in liver and serum. The data processed by principle component analysis (PCA) showed time-dependent biochemical variations. As a consequence, the present study may offer specific putative pathways in the pathophysiological mechanism of orthotopic liver transplantation.     

Determination of salicylate in beverages and cosmetics by use of an amperometric biosensor

A fast and selective enzymatic method for the determination of salicylate in beverages and cosmetics has been developed. The enzyme salicylate hydroxylase was immobilised covalently onto a glassy carbon working electrode of a wall-jet cell coupled with a flow-injection analysis system. The salicylate is enzymatically converted to catechol, which can be detected amperometrically on the glassy carbon electrode at +0.45 V. The response of the biosensor is linearly proportional to the concentration of salicylate between 725 nmol/l and 700 mol/l. A high sample throughput (60 h^-1) is possible, and the biosensor is stable for more than three months. Sample pretreatment for beverages and hair lotions is easy and fast. For creams, an extraction of salicylate is necessary. Relative standard deviations are less than 5.5% and the recoveries are between 95 and 105%.     

Alterations of epinephrine-induced gluconeogenesis in aging

The effects of glucagon and epinephrine on gluconeogenesis in young (4 month) and old (24 month) Fisher 344 rat hepatocytes were compared. In contrast to glucagon, which had a similar effect on gluconeogenesis in both young and old cells, epinephrine caused a smaller increase in gluconeogenesis in old rat hepatocytes than in young hepatocytes. β₂ adrenergic receptor (β₂-AR) expression slightly decreased in aged rat liver, and there were differences between young and old hepatocytes in their patterns of G protein coupled receptor kinases, which are involved in the activation of β₂-AR receptor signal desensitization. The major isoform of the kinase changed from GRK2 to GRK3 and the expression of β-arrestin, which is recruited by the phosphorylated β₂-AR for internalization and degradation, increased in aged rat liver. GRK3 overexpression also decreased the glucose output from young rat hepatocytes. We conclude that an age-associated reduction in epinephrine-induced gluconeogenesis occurs through the epinephrine receptor desensitizing system.     

Improvement of graft function and animal survival by fat emulsion in liver transplant rats

Nutritional supports are required for liver transplant patients. However, no systematical assessment has been made of the optimal composition of energy yielding substrates in these patients. This study is to evaluate whether mixed energy system consisting of carbohydrate and lipid emulsions is more advantageous over single energy source of glucose for nutritional support in liver transplant recipients and whether structured lipid emulsion (STG) is superior to medium-chain triglyceride/long-chain triglycerides (MCT/LCT) and long-chain triglycerides (LCT) using a total parenteral nutrition model. Liver transplant rats were randomly divided to four groups according to the energy source, i.e. glucose (GLU), MCT/LCT, STG and LCT groups. Sham operated rats served as control. Hepatic function and lipid profile were determined to investigate the roles of lipid emulsion in hepatic function and lipid metabolism. Morphological changes of liver were observed, and nitrogen balance was determined. The results showed that infusion of lipid emulsion was well tolerated. The 1-week survival rate in the lipid emulsion groups was significantly higher than in the GLU group (100% versus 50%, P<0.05); compared with the GLU group, hepatic function recovered quickly and returned to normal level, and morphological alterations were less severer in the lipid emulsion groups, especially in the STG group; the lipid emulsions groups had normal serum TG and TC levels, especially STG and MCT/LCT groups; the lipid emulsions groups achieved a positive nitrogen balance on day 7 compared with the GLU group, and the STG group had the highest nitrogen balance. In conclusion, lipid emulsion is beneficial in improving hepatic function and the recipients' survival and does not influence the lipid metabolism. Mixed energy system consisting of carbohydrate and lipid is more advantageous over single energy source of glucose after liver transplantation, and STG is superior to MCT/LCT and LCT.