谷氨酰胺在危重病患者中的应用

目的探讨危重病患者中早期经静脉应用谷氨酰胺（glutamine，Gl）的临床价值。方法42例患者随机分成两组（对照组和Gln组），Gln组进行Gln治疗（100mL／d，共7d）。治疗前后检测患者体质量、白蛋白、谷胱甘肽（GSH）、握力的变化和肠功能不全的发生率。结果体质量两组治疗前后比较差异无显著性（P〉0．05）。白蛋白、握力和GSH Gl治疗后非常显著高于治疗前（P〈0．01）；白蛋白对照组治疗后较治疗前显著增高（P〈0．05），但握力和GSH治疗前后均无显著变化（P〉0.05）；肠功能不全的发生率Gln组为4．8％，显著低于对照组（28．6％，P〈0．05）。结论在危重病患者疾病早期通过静脉途径外源性地补充Gln，有效改善了患者的营养状况；使患者血浆中的GSH水平增高，加强了机体的抗氧化能力；减少了患者肠功能不全的发生率。     

Modification of the Phe3 aromatic moiety in delta receptor-selective dermorphin/deltorphin-related tetrapeptides Effects on opioid receptor binding

The previously described cyclic delta opioid receptor-selective tetrapeptide H-Tyr-d -Cys-Phe-d -Pen-OH (JOM-13) was modified at residue 3 by incorporation of both natural and unnatural amino acids with varying steric, electronic, and lipophilic properties. Effects on mu and delta opioid receptor binding affinities were evaluated by testing the compounds for displacement of radiolabeled receptor-selective ligands in a guinea pig brain receptor binding assay. Results obtained with the bulky aromatic 1-Nal³ and 2-Nal³ substitutions suggest that the shape of the receptor subsite with which the side chain of the internal aromatic residue interacts differs for delta and mu receptors. This subsite of either receptor can accommodate the transverse steric bulk of the 1-Nal³ side chain but only the delta receptor can readily accept the more elongated 2-Nal³ side chain. Several analogs with pi-excessive heteroaromatic side chains in residue 3 were examined. In general, these analogs display diminished binding to mu and delta receptors, consistent with previous findings for analogs with residue 3 substitutions of modified electronic character. Several analogs with alkyl side chains in residue 3 were also examined. While delta receptor binding affinity is severely diminished with Val³, Ile³, and Leu³ substitutions, Cha³ substitution is very well tolerated, indicating that, contrary to the widely held belief, an aromatic side chain in this portion of the ligand is not required for delta receptor binding. Where possible, comparison of results in this delta-selective tetrapeptide series with those reported for analogous modification in the cyclic delta-selective pentapeptide [d -Pen², d -Pen⁵]enkephalin (DPDPE) and linear pentapeptide enkephalins reveals similar trends.     

Antigen unfolding and disulfide reduction in antigen presenting cells

CD4+ helper T cells recognize short peptides stably associated with class II MHC molecules displayed on the surface of antigen presenting cells. Very little is known about the sequence of events that lead to the generation of these peptides from protein antigens. It is likely that native proteins must partially unfold before they are cleaved by endopeptidases or bind to MHC proteins. For many antigens, the rate-limiting step in unfolding may involve reduction of disulfide bonds. Evidence that disulfide reduction occurs in endocytic compartments is reviewed and potential mechanisms for the reduction of antigen disulfide bonds are proposed.     

Lipid peroxidation and antioxidant status in human cervical carcinoma

Reactive oxygen species (ROS), represented by superoxide, hydrogen peroxide and hydroxyl radicals, have been implicated in many diseases including cancer. ROS have been known to play an important role in the initiation and promotion of multistep carcinogenesis. The cellular antioxidants play a crucial role in protection against neoplastic disease. However, very little is known about the antioxidant defense in cervical carcinoma. This is addressed in the present study. Lipid peroxides, glutathione content and the activities of antioxidant enzymes, together with vitamin C and E content, were estimated in patients who had carcinoma of the cervix, and the values were compared with those of normal women. The results showed a remarkable reduction in the content of glutathione, vitamin E and C. Activities of glutathione peroxidase and superoxide dismutase were also reduced in cervical cancer compared to normal controls (P < 0.001). This reduction was more marked in late stages (III, IV) than in early stages (I, II) (P < 0.001). Glutathione was reduced more in poorly differentiated tumors (grade III) than in well and moderately differentiated ones (grade I, II) (P < 0.05). Levels of lipid peroxides were found to be significantly higher in malignant than in normal tissue samples and their levels were correlated with advanced clinical stage (P < 0.001). Our results suggest impaired antioxidant status in carcinoma of the cervix. This impairment is related to tumor progression.     

Breast cancer: Pretreatment drug resistance parameters (GSH-system, ATase, P-glycoprotein) in tumor tissue and their correlation with clinical and prognostic characteristics

Background: The identification of new factors predicting relapse,outcome and response to systemic therapy in breast cancer is warranted. Themeasurement of biological markers such as drug resistance parameters (DRPs),which are part of the phenotype of malignant cells and contribute toresistance to anti-cancer drugs may be a possibility, which may ultimatelylead to improvement of therapeutic results.Patients and methods: The level of glutathione (GSH), activities ofglutathione-S-transferase (GST), glutathione-peroxidase (GPx),06-alkylguanine-DNA-alkyltransferase (ATase), and P-glycoprotein (PGP) weremeasured in tumor and adjacent tumor free tissue samples from 89 consecutive,untreated females with breast cancer and correlated with clinical andprognostic factors. Early breast cancer (EBC) was diagnosed in 56 patients,22 patients had locally advanced (LABC) and 11 patients metastatic breastcancer.Results: All DRPs showed significantly higher expression in tumorthan in tumor free tissues. GPx was positively correlated with GST (R = 0.3, P = 0.0048) and with GSH (R = 0.5, P = 0.0001) in tumor as wellas in normal tissue. GST activity was significantly higher in EBC than in LABCor metastatic breast cancer ( P = 0.02). GSH level was significantlyhigher in grade 1 than in grade 2 or grade 3 tumors ( P = 0.01). Whenclinical characteristics were related to the level of DRP, high GSH wasassociated with age >60 years ( P = 0.01) in EBC, and with grade1–2 tumors ( P = 0.05) in LABC. No differences in OS were apparentbetween groups of high and low DRP-expression. However, the four-yearestimated disease-free survival of EBC tended to be higher in patients withhigh GST ( P = 0.10) and of LABC in patients with high GPx levels( P = 0.06).Conclusion: We conclude that high levels of DRP in tumor tissue ofbreast cancer patients are part of the initial phenotype of the malignantcells. Due to its high prevalence (83% in EBC, 100% in primarilymetastatic breast cancer), PGP did not add to prognostic information. Highlevels of GSH, GST and and GPx were associated with favorable clinicalcharacteristics and good prognosis, whereas low levels of GSH and GST activitywere associated with more aggressive or more advanced disease.     

慢性低浓度二硫化碳接触作业工人血脂的变化

对某化纤厂99名长期接触低浓度二硫化碳（CS2）作业工人和28名同厂非CS2作业工人的血脂进行流行病学横断面调查。结果发现：除接触组脂蛋白（a）［Lp（a）］浓度明显高于对照组外,其它血脂指标差别均无统计学意义;进一步通过多元逐步回归分析发现,长期低浓度CS2接触对Lp（a）的影响最大,二者呈正相关（r＝0．43,P＜0．01）。提示Lp（a）可能在CS2致脂质代谢障碍毒作用机制中起着重要作用。     

15kg负重沙漠干热应激行军速度和时间对人体GSH和SOD的影响

目的　探讨沙漠干热负重应激行军人体ＧＳＨ 和ＳＯＤ 作用机制。方法　对７４ 名１５ ｋｇ 负重在沙漠干热环境以不同速度和时间行军战士和对照人群血浆的变化进行了研究。结果　１５ ｋｇ 负重,３－５ｋｍ／ｈ 和５ ｋｍ／ｈ 行军者ＧＳＨ 在应激的最初１ 小时内迅速上升,约１ 小时达到高峰,之后迅速下降;随着行军速度的增加,机体抗氧化作用所消耗的ＳＯＤ 量增加,血浆ＳＯＤ 浓度亦随之下降。结论　从行军时间来看,在应激的最初１ 小时内,因应激诱导的ＧＳＨ 的合成和ＳＯＤ 的量增加,故沙漠干热环境负荷应激行军以１５ ｋｇ、３－５ ｋｍ／ｈ 为宜。     

砷对小鼠脂质过氧化和抗氧化能力的影响

采用动物实验方法,研究砷对小鼠各组织ＭＤＡ含量,ＳＯＤ活力及全血ＧＳＨ－Ｐｘ活力的影响。结果显示：心脏的中、高剂量组ＭＤＡ水平显著高于对照组和低剂量组,而ＳＯＤ活力则是中、高剂量组显著低于对照组和低剂量组;肝脏的染毒组ＭＤＡ水平均显著高于对照组,而ＳＯＤ活力低剂量组显著高于其它３组,中、高剂量组显著低于对照组和低剂量组;肾脏中仅高剂量组ＭＤＡ水平显著高于对照组,而ＳＯＤ活力各组间无显著差异。全血中的ＧＳＨ－Ｐｘ活力显著下降,并呈剂量－效应关系。表明,砷可促进机体脂质过氧化,抑制抗氧化酶（ＳＯＤ,ＧＳＨ－Ｐｘ）的活力。     

Effect of tetrakis-μ-3,5-diisopropylsalicylatodiaquodicopper(II) on the status of reduced glutathione in freshly isolated hepatocytes

Effects of different concentrations of tetrakis--3,5-diisopropylsalicylatodiaquodicopper(II) (Cu(II)₂(3,5-DIPS)₄(H₂O)₂) on the reduced status of glutathione (GSH), the major nonprotein thiol in tissues, were investigated using freshly isolated hepatocytes. Cu(II)₂(3,5-DIPS)₄ below 100 M did not have any significant effects on either the GSH content or viability of the hepatocytes, but at 150–250 M it decreased both parameters after 1 h of incubation. The decrease in cellular GSH was not followed by an increase in the oxidized form of GSH (GSSG) in the cell suspension. The addition of deferoxamine with Cu(II)₂(3,5-DIPS)₄ to the hepatocyte suspension prevented depletion in GSH content and loss of cell viability by Cu(II)₂(3,5-DIPS)₄. Both GSH depletion and loss of cell viability were found to be Cu(II)₂(3,5-DIPS)₄ dose dependent. From these results, it appears that Cu(II)₂(3,5-DIPS)₄ penetrated the cell membrane and acted by decreasing the GSH level by forming a copper-glutathione complex.     

Characterizing the influence of structure and route of exposure on the disposition of dithiocarbamates using toluene-3,4-dithiol analysis of blood and urinary carbon disulfide metabolites.

Differences in the toxicities observed for dithiocarbamates have been proposed to result from the influence of nitrogen substitution, oxidation state, and route of exposure. To better characterize the fate of dithiocarbmates in vivoas a function of structure and route of exposure, rats were administered equimolar doses of carbon disulfide (CS2), N-methyldithiocarbamate, pyrrolidine dithiocarbamate, N,N-diethyldithiocarbamate, or disulfiram daily for five days, either po or ip, and sequential blood samples obtained. Protein dithiocarbamates formed by the in vivo release of CS2, parent dithiocarbamate, and protein-bound mixed disulfides were assessed in plasma and hemolysate by measuring toluene trithiocarbonate generated upon treatment with toluene-3, 4-dithiol (TdT). To aid in determining the bioavailability of CS2 from the administered dithiocarbamates, the urinary CS2 metabolites, 2-thiothiazolidine-4-carboxylic acid (TTCA) and 2-thiothiazolidin-4-ylcarbonylglycine (TTCG), were also determined. The levels of TdT-reactive moieties detected depended upon both the compound administered and the route of exposure. Parent dithiocarbamates, with the exception of disulfiram, were eliminated from blood within 24 h; but protein associated TdT-reactive moieties persisted and accumulated with repeated exposure, regardless of the route of exposure. N-Methyldithiocarbamate demonstrated the greatest potential to produce intracellular globin modifications, presumably through its unique ability to generate a methylisothiocyanate metabolite. Urinary excretion of TTCA and TTCG was more sensitive than TdT analysis for detecting dithiocarbamate exposure, but TdT analysis appeared to be a better indicator of in vivo release of CS2 by dithiocarbamates than were urinary CS2 metabolites. These data suggest that CS2 is a more important metabolite, following oral exposure, than are other routes of exposure, e.g., inhalation or dermal. In addition, data also suggest that acid stability, nitrogen substitution, and route of exposure are important factors governing the toxicity observed for a particular dithiocarbamate.