低剂量铅对大鼠脑组织一氧化氮合酶表达及活性的影响

为探讨低水平铅损伤记忆功能的作用机理，采用ＮＡＤＰＨ－黄递酶组织化学方法和＾３Ｈ－瓜氨酸生成生物检测技术，观察了新生大鼠在４００ｍｇ／Ｌ醋酸铅染毒４０天后对脑组织内一氧化氮合酶表达及活性的影响。结果显示大脑皮质一氧化氮合酶阳性神经元数量明显减少（Ｐ〈０．０５），在海马区脑组织内一氧化氮合酶活性降低５４．４％。结论：低水平铅暴露后可抑制大鼠脑组织内一氧化氮合酶的表达及活性。     

Transketolase from human erythrocytes. Purification and properties

Human erythrocyte transketolase (sedoheptulose-7-phosphate: D-glyceraldehyde-3-phosphate glycolaldehyde-transferase) was purified 8200-fold by adsorption onto hydroxylapatite, DEAE-cellulose treatment, acetone fractionation, and chromatography on Sephadex G-100. The purified transketolase could not be separated from glyceraldehyde-3-phosphate dehydrogenase, whereas the latter enzyme could be isolated in a pure state. Its homogeneity is suggested by sedimentation velocity, sedimentation equilibrium, and acrylamide electrophoresis. A molecular weight of 136000 was found. The physicochemical properties of glyceraldehyde-3-phosphate dehydrogenase and transketolase are very similar. A molecular weight of 136000 is suggested for transketolase, although gel filtration with Sephadex G-100 gave only 104000 ± 10%. This discrepancy is a reflection of an interaction of transketolase with the gel filtration medium. The isoelectric point for transketolase as well as for glyceraldehyde-3-phosphate dehydrogenase, as determined by isoelectric focussing, was found to be around 8.5. The activity of the enzyme is close to the maximum for pH 7.5 to pH 8.6. Additions of thiamine pyrophosphate or other cofactors do not influence the activity. Several divalent cations were tested. Sulfate and phosphate inhibit transketolase approximately to 50% between 50 and 100 mM concentration. Thiamine was present in transketolase, as shown by a microbiological assay and by the thiochrome reaction. The activation energy for the formation of sedoheptulose-7-phosphate from xylulose-5-phosphate was estimated from rate measurements to be 11.2 kcal/mole in the temperature range from 5° to 55°.     

Influence of Dietary Chitosan Feeding Duration on Glucose and Lipid Metabolism in a Diabetic Rat Model

This study was designed to investigate the influence of dietary chitosan feeding-duration on glucose and lipid metabolism in diabetic rats induced by streptozotocin and nicotinamide [a non-insulin-dependent diabetes mellitus (NIDDM) model]. Male Sprague-Dawley rats were used as experimental animals and divided into short-term (6 weeks) and long-term (11 weeks) feeding durations, and each duration contained five groups: (1) control, (2) control + 5% chitosan, (3) diabetes, (4) diabetes + 0.8 mg/kg rosiglitazone (a positive control), and (5) diabetes + 5% chitosan. Whether the chitosan feeding was for 6 or 11 weeks, the chitosan supplementation decreased blood glucose and lipids levels and liver lipid accumulation. However, chitosan supplementation decreased plasma tumor necrosis factor (TNF)-α, insulin levels, alanine aminotransferase (ALT) activity, insulin resistance (HOMA-IR), and adipose tissue lipoprotein lipase activity. Meanwhile, it increased plasma high-density lipoproteins (HDL)-cholesterol level, plasma angiopoietin-like-4 protein expression, and plasma triglyceride levels (at 11-week feeding duration only). Taken together, 11-week (long-term) chitosan feeding may help to ameliorate the glucose and lipid metabolism in a NIDDM diabetic rat model.     

Direct carboxylation reaction of methane with CO by a Yb(OAc)3/Mn(OAc)2/NaClO/H2O catalytic system under very mild conditions

A new method of synthesis of acetic acid in water has been developed from the carboxylation of methane with carbon monoxide using lanthanide catalysts. Ytterbium(III) acetate has been found to be the most active catalyst among the compounds of the lanthanide series in the carboxylation reaction of methane with carbon monoxide. Sodium hypochlorite or hydrogen peroxide was used as the oxidant in this reaction. Sodium hypochlorite exhibited more favorable activity than hydrogen peroxide in the reaction. The catalytic activity was improved by the addition of transition-metal salts such as manganese(II) acetate. The best result has been found at a ratio of manganese(II) acetate to ytterbium(III) acetate of 1:10. The optimum reaction conditions (reaction temperature, 40 °C; time, 20 h; methane, 20 atm; carbon monoxide, 5 atm) have been obtained. © 1998 John Wiley & Sons, Ltd.     

Effect of water extracts of aloe and some herbs in decreasing blood ethanol concentration in rats. II

Oral administration of ethanol to rats at a dose of 3 g/kg decreased alcohol dehydrogenase (ADH) activity and metabolism of lactate to pyruvate in the liver. The effects of water extracts of Aloe and some other herbs on blood ethanol concentration and on ADH activity in liver cytosol were examined. The water extracts of these herbs caused a faster elimination of ethanol from blood of normal rats when administered orally 30 min before oral administration of ethanol. The rapid elimination of ethanol seems to be due to a protection of ADH activity and the supply of nicotinamide dinucleotide, both of which are reduced by high ethanol concentration. The effects of ethanol in decreasing the enzyme activities relating to its own metabolism occur when high concentrations of ethanol pass through the liver, and thus may primarily appear during the absorption of alcohol from the gastrointestinal tract, when portal concentration of ethanol are very high.     

Antihepatotoxic and antioxidant activities of methanol extract and isolated compounds from Ficus chlamydocarpa

Free radicals, in particular radical oxygen species (ROS), play an important role in the aetiology and pathogenesis of various diseases. Current research in many countries focuses on the use of local medicinal plants as a promising source of liver protective agents. This paper describes the hepatoprotective effects of the methanol extract and four isolated compounds from Ficus chlamydocarpa on CCl4-induced liver damage, as well as the possible antioxidant mechanisms involved in this protection. The DPPH test, along with the beta-Carotene-Linoleic Acid Model System and Ferric-Reducing Antioxidant Power assays, as well as the inhibition of microsomal lipid peroxidation were used to measure radical-scavenging and antioxidant activities. Pretreatment of rats with the methanol extract of F. chlamydocarpa before CCl4 administration, significantly prevented serum increase of hepatic enzyme markers, glutamate oxaloacetate transaminase (GOT) and glutamate pyruvate transaminase (GPT), in a dose-dependent manner. The hepatoprotection was also associated with a significant enhancement in hepatic reduced glutathione (GSH) and a marked decrease of liver malondialdehyde (MDA). Among the four compounds 1-4, isolated from the methanol extract, alpha-amyrin acetate (1) and luteolin (4) showed a significant hepatoprotective activity, as indicated by their ability to prevent liver cell death and lactate dehydrogenase (LDH) leakage during CCl4 intoxication.     

高效液相色谱β-环糊精键合固定相直接拆分硫代和硒代缩水甘油醚对映异构体

 用两种不同的方法合成了β-环糊精键合固定相。通过对硝基苯胺异物体的拆分,对键合相进行了评价。拆分了3种硫代缩水甘油醚和2种未见文献报道的硒代缩水甘油醚。     

Ginsenoside Rb1 attenuates intestinal ischemia-reperfusion-induced liver injury by inhibiting NF-��B activation

Intestinal ischemia-reperfusion (I/R) is an important event in the pathogenesis of multiple organ dysfunction syndrome (MODS). The aim of this study is to determine the effects of ginsenoside Rb1 on liver injury induced by intestinal I/R in rats. Adult male Wistar rats were randomly divided into four groups: (1) a control, sham-operated group (sham group); (2) an intestinal I/R group subjected to 1 h intestinal ischemia and 2 h reperfusion (I/R group); (3) a group treated with 20 mg/kg ginsenoside Rb1 before reperfusion (Rb1-20 group); and (4) a group treated with 40 mg/kg ginsenoside Rb1 before reperfusion (Rb1-40 group). Liver and intestinal histology was observed. Aspartate aminotransferase (AST), alanine aminotransferase (ALT) level in serum and malondialdehyde (MDA) level in intestinal tissues were measured. Myeloperoxidase (MPO), TNF-α, MDA level and immunohistochemical expression of NF-κB and intracellular adhesion molecale-1 (ICAM-1) in liver tissues was assayed. In addition, a western blot analysis of liver NF-κB expression was performed. Results indicated intestinal I/R induced intestinal and liver injury, which was characterized by increase of AST and ALT in serum, MDA level in intestine, MPO, TNF-α and MDA level and ICAM-1 and NF-κB expression in the liver tissues. Ginsenoside Rb1 (20, 40 mg/kg) ameliorated liver injury, decreased MPO, TNF-α and MDA level, NF-κB and ICAM-1 expression in liver tissues. In conclusion, ginsenoside Rb1 ablated liver injury induced by intestinal I/R by inhibiting NF-κB activation.     

Microsomal delta 9, delta 6 and delta 5 desaturase activities and liver membrane fatty acid profiles in alcohol-fed rats

In experimentally produced alcoholic fatty liver microsomal fatty acid composition was measured using gas chromatography. The results showed an increase in linoleic acid (18:2, n-6) and hexadecaenoic acid (22:6, n-3) and a decrease in arachidonic acid (20:4, n-6) in alcohol-fed rats. Using high performance liquid chromatographic separation of radiolabelled substrate and products, delta 9, delta 6 and delta 5 desaturase enzymes were assayed. The activity of delta 9 and delta 5 desaturase was decreased in alcohol-fed rats and delta 6 desaturase activity was similar in control and alcohol-fed groups. These results indicated there was no causal relationship between desaturase activity and membrane fatty acid changes. Increased amounts of eicosatrienoic acid (20:3, n-9) in rats fed less than 5% fat were observed in both control and alcohol-fed rats. The results indicated that essential fatty acid deficiency was not due to alcohol consumption.     

Determination of cadmium and lead in the low ng/l range by stripping potentiometry employing medium exchange in batch mode and multiple stripping in a hanging stripping medium drop

A novel three-in-one electrode assembly, permitting medium exchange under a controlled potential in batch mode by exploiting electrolytic conductance through a drop hanging under the electrode, has been used for the simultaneous determination of cadmium(II) and lead(II) at trace levels. Potentiostatic reduction and amalgamation of these ions are carried out in the sample and the subsequent stripping, in the stripping potentiometry mode, in a drop of a suitable medium. Several such media have been investigated, a mixture of 2.5M acetic acid and 7.5M ammonium acetate having been found to be the most suitable with respect to sensitivity, potential resolution and trace metal purity. The quiescent conditions in the drop of medium facilitated multiple stripping and thus increased sensitivity. Detection limits for cadmium(II) and lead(II) were found to be around 0.5 ng/l. (5 and 2.5pM) for an electrolysis time of 10 min. The relative precision at the concentration level 20 ng/l. was 6.4% for cadmium and 5.4% for lead. The procedure has been used for the determination of cadmium(II) and lead(II) in reference seawater samples.     

三(2-苯并咪唑甲基)胺-锌(Ⅱ)配合物模拟水解酶催化酯类水解研究

研究了三(2-苯并咪唑甲基)胺-锌(II)配合物作为水解酶模拟物催化乙酸对硝基苯酯(NA)水解动力学.结果表明,催化水解速率对NA及配合物浓度呈一级反应.水解速率遵循速率方程v=(k_cat[Zn]＋k_OH[OH^－]＋k₀)[NA].在298K,I=0.10mol/LKNO₃,0.02mol/LTris,40％CH₃CN水溶液中,二级反应速率常数k_cat和k_OH分别为0.12、1.45mol^－1·L·S^－1,k₀为NA溶剂解的速率常数,其值为3.70×10^－6s^－1.与10％CH₃CN溶液中的k₀值相比,40％CH₃CN水溶液中的k₀值明显降低.本研究表明三(2-苯并咪唑甲基)胺-锌(II)配合物能有效地催化NA的水解.配合物对NA水解的催化作用受酸碱平衡控制.根据实验结果提出了催化反应的机理.     

Regulation of glucocorticoid receptor by glucocorticoids (II)--The studies on rat liver, brain and spleen

The concentration of glucocorticoids (GC) in plasma was maintained at stress level, 20-40 micrograms/dl, for 3 days by subcutaneous injection of hydrocortisone (F) in polyvinyl alcohol (PVA) into rats, and the specific binding of [3H]Dexamethasone (Dex) in liver, spleen and brain was determined before and after injection. The binding capacity of glucocorticoid receptor (GR) in liver and spleen was decreased significantly 1 h after injection and maintained at low level for several days after the concentration of GC in plasma had returned to the normal level. The Kd was not altered. The changes of GR in brain was not significant. Thus it may be concluded that GC can down-regulate GR in rats, but with different characteristics in various target organs.     

Supercritical fluid extraction of aurentiamide acetate from Patrinia villosa Juss and subsequent isolation by silica gel and high-speed counter-current chromatography

Supercritical fluid extraction (SFE) of aurentiamide acetate from Patrinia villosa Juss was performed. The optimization of parameters was carried out using an analytical-scale supercritical fluid extraction (SFE) system. Then the extraction was scaled up by 100 times using a preparative SFE system under the optimized conditions of 55 degrees C, 35 MPa and modified CO2 with 10% methanol. Then, the crude extract I obtained by SFE was chromatographed on silica gel and the solvent system composed of petroleum ether-ethyl acetate (5:1, v/v) was used to produce the crude extract II, which was further isolated and purified by high-speed counter-current chromatography (HSCCC) with a two-phase solvent system composed of n-hexane-ethyl acetate-methanol-water (1:1.2:1.2:1, v/v/v/v). One hundred fifty-five milligrams of aurentiamide acetate was obtained from 400 mg crude extract II (contained 42% target) with a purity of 99.3% determined by HPLC and 92.3% recovery in one-step elution, and identification was performed by UV, MS, 1H NMR and 13C NMR. As far as we know, this is the first report of discovering aurentiamide acetate from the plant of Patrinia genius.     

In vitro metabolism of specific CYP2D and CYP3A opioid substrates using rat liver S9 fractions and mass spectrometry reveal a severe metabolic impairment with increasing age

Codeine and oxycodone are opioids used to alleviate pain. The outcome of the treatment is ultimately related to their metabolism by Cytochromes P450 (CYPs). Depending on the drugs used, alterations in the metabolism of drugs by CYPs can lead to severe consequences including alterations in their efficacy, safety and toxicity. The objectives of this study were to develop a novel HPLC–MS/MS method capable of quantifying codeine and oxycodone along with specific metabolites using an isotopic dilution strategy and study the rate of formation of morphine (CYP2D), norcodeine (CYP3A), oxymorphone (CYP2D) and noroxycodone (CYP3A). The chromatographic separation was achieved using a Biobasic C₁₈ 100 × 1 mm column combined with an isocratic mobile phase composed of methanol and 10 mm ammonium acetate (40:60) at a flow rate of 75 μL/min. The mass spectrometer was operating in scan mode MS/MS and the analytical range was set at 10–10 000 nm . The precision (RSD) and accuracy (RE) observed were 4.4–11.5 and −9.1–6.1% respectively. Liver S9 fractions from 3‐, 6‐, 12‐ and 18‐month‐old male Sprague–Dawley rats were prepared and Michaelis–Menten parameters were determined. The derived maximum enzyme velocity suggested a rapid saturation of the CYP2D and CYP3A active sites in the liver S9 fractions of 18‐month‐old rats. Moreover, metabolic stabilities of codeine and oxycodone in rat liver S9 fractions were significantly greater for the 18‐month‐old rats. This study suggests that there is an impairment of CYP2D and CYP3A metabolism in aging rats.     

Phytochemical investigation and hepatoprotective activity of Cupressus sempervirens L. leaves growing in Egypt

Three phenolic compounds cosmosiin, caffeic acid, and p-coumaric acid were isolated for the first time from the leaves of Cupressus sempervirens L., together with cupressuflavone, amentoflavone, rutin, quercitrin, quercetin, myricitrin. The isolated compounds were identified using (1)H- and (13)C-NMR spectra. The hepatoprotective activity of the MeOH extract was carried out in liver homogenate of normal and CCl(4)-treated rats; a significant decrease in glutamate oxaloacetate transaminase, glutamate pyruvate transaminase, cholesterol level, and triglycerides, while a significant increase in the total protein level, was observed after the oral administration of MeOH extract. The free radical scavenging activity against stable 2,2-diphenyl-2-picrylhydrazyl (DPPH*) was measured for MeOH extract and some of the isolated phenolic compounds in comparison with alpha-tocopherol and butylated hydroxy toluene as standard antioxidants using ESR technique, showed high antioxidant activity for quercetin, rutin, caffeic acid, and p-coumaric acid.     

用高效液相色谱法测定热应激时大鼠肺及肝组织中细胞膜磷脂的变化

 应用高效液相色谱法（ＨＰＬＣ）测定了正常大鼠肺及肝组织中细胞膜磷脂的含量及热应激时膜磷脂的含量变化。流动相为甲醇∶乙腈∶８５％磷酸（３∶１００∶１，Ｖ／Ｖ／Ｖ），色谱柱为μ－Ｐｏｒａｓｉｌ柱（３．９ｍｍｉ．ｄ．×３００ｍｍ）。通过测定膜磷脂的变化，可以为阐明机体的发病机理提供可靠的数据。     

Curative Effect of Catechin Isolated from Elaeagnus Umbellata Thunb. Berries for Diabetes and Related Complications in Streptozotocin-Induced Diabetic Rats Model

In this study, catechin (CTN) isolated from Elaeagnus umbellata was evaluated for in vitro antioxidant potential and inhibition of carbohydrate digestive enzymes (α-amylase and α-glucosidase). The compound was also tested for its in vivo antidiabetic potential using Sprague-Dawley rats as experimental animals. The effects of various doses of catechin in STZ (Streptozotocin) induced diabetic rats on fasting blood glucose level, body weight, lipid parameters, hepatic enzymes, and renal functions were evaluated using the reported protocols. The CTN exhibited the highest percent antioxidant for free radical scavenging activity against DPPH and ABTS free radicals, and inhibited the activity of carbohydrate digestive enzymes (with percent inhibition values: 79 ± 1.5% α-amylase and 80 ± 1.1% α-glucosidase). Administration CTN and standard glibenclamide significantly decreased the fasting blood glucose level and increased the body weight in STZ-induced diabetic rats. CTN significantly decreased the different lipid parameters, hepatic, and renal function enzyme levels along with Hb1c level in diabetic rats, while significantly increasing the high-density lipoprotein (HDL) level with values comparable to the standard glibenclamide. Further, the altered levels of glutathione and lipid peroxides of liver and kidney tissues were restored (by CTN) to levels similar to the control group. CTN significantly increased the antioxidant enzyme activities, total content of reduced glutathione, and reduced the malondialdehyde (MDA) level in rat liver and kidney tissues homogenates, and also corrected the histopathological abnormalities, suggesting its antioxidant potential.     

Enzyme-catalyzed synthesis of nucleoside triphosphates from nucleoside monophosphates

Syntheses of adenosine 5′-triphosphate (ATP) from adenosine 5′-monophosphate (AMP) and ribavirin 5′-triphosphate (RTP) from ribavirin 5′-monophosphate (RMP) (1) were performed using enzymes as catalysts. Synthesis of ATP is based on acetyl phosphate as the phosphate donor, and acetate kinase (Bacillus stearothermophilus, EC 2.7.2.1), adenylate kinase (porcine muscle, EC 2.7.4.3), and inorganic pyrophosphatase (yeast, EC 2.6.1.1) as the catalysts. Three reactions on a 150-mmol scale provided ATP as its barium salt in 82% yield and 67% purity. Synthesis of RTP used phosphoenol pyruvate (PEP) as the phosphate donor, and pyruvate kinase (rabbit muscle, EC 2.7.1.40) and adenylate kinase (rabbit muscle) as the catalysts. A gram-scale reaction provided RTP as its barium salt in 93% yield and 97% purity. This work demonstrates the utility of the autoxidationresistant acetate kinase fromB. stearothermophilus, the value of pyrophosphatase in controlling the level of pyrophosphate in the reactions and the ability of adenylate kinase to accept at least one substrate other than a derivative of adenosine.     

Effect of myricetin on deoxycorticosterone acetate (DOCA)-salt-hypertensive rats

Chronic administration of myricetin (100 and 300?mg?kg?1, p.o., for 4 weeks) isolated from Vitis vinifera (Vitaceae) ameliorated hypertension and oxidative stress induced by deoxycorticosterone acetate (DOCA)-salt in rats. Myricetin treatment reduced systolic blood pressure, vascular reactivity changes and reversed the DOCA-induced increase in heart rate. Urinary sodium excretion was significantly decreased in animals treated with myricetin compared to the DOCA group when measured by flame photometer. The cumulative concentration response curve of serotonin (5-HT) and angiotensin II (Ang II) were shifted towards the right in rats treated with myricetin using the isolated rat fundus strip and ascending colon, respectively. Increased levels of thiobarbituric acid reactive substances and decreased levels of superoxide dismutase, catalase and reduced glutathione in the heart tissue were observed in animals treated with DOCA, which were reversed by myricetin. Thus, myricetin shows antihypertensive and antioxidant properties in the DOCA model of hypertension.