Quantification of Basal and Stimulated ROS Levels as Predictors of Islet Potency and Function

We have developed a luminol-based assay using intact islets, which allows for quantification of reactive oxygen species (ROS). In addition, an index capable of characterizing metabolic and mitochondrial integrity prior to transplantation was created based on the capacity of islets to respond to high glucose and rotenone (mitochondrial respiratory chain complex I inhibitor) by production of ROS. To validate this assay, lipid peroxidation and antioxidative defense capacity were evaluated by detection of malondialdehyde (MDA) levels and glutathione peroxidase activity (GPx), respectively. Also, flow cytometric analyses of ROS (dihydroethidine), apoptosis (Annexin V, active caspases), necrosis (Topro3), and mitochondrial membrane potential (JC-1) were done in parallel to correlate with changes in luminol-measured ROS. ATP/ADP ratios were quantified by HPLC and the predictive value of ROS measurement on islet functional potency was correlated with capacity to reverse diabetes in a streptozotocin-induced diabetic NOD.scid mouse model as well as in human transplant recipients. Our data demonstrate that levels of ROS in islets correlate with the percentage of apoptotic cells and their functional potency in vivo. The ROS indices following glucose and rotenone exposure are indicative of metabolic potency and mitochondrial integrity and can be used as surrogate markers to evaluate the quality of islets prior to transplantation.     

Studies on the optimal conditions for inactivation of Bordetella pertussis organisms with glutaraldehyde for preparation of a safe and potent pertussis vaccine

The optimal conditions for inactivation of Bordetella pertussis organisms with glutaraldehyde for the production of a safe and potent whole cell pertussis vaccine were investigated. Two bacterial harvests from B. pertussis strain 10536 were treated with glutaraldehyde, each with 0.025, 0.05 and 0.1% concentrations of glutaraldehyde for 10, 60 and 120 min. The nine types of glutaraldehyde-inactivated pertussis vaccine (GIPV) and conventional heat-inactivated pertussis vaccine (HIPV) preparations made from two bacterial harvests were comparatively evaluated for the mouse weight gain test (MWGT), potency, and the histamine-sensitization (HS) and leucocytosis-promoting-factor (LPF) tests. The minimum period for killing the B. pertussis organisms with glutaraldehyde was>10 min for 0.025%, 10 min for 0.05% and 5 min for 0.1% concentration. The average loss in opacity varied from 5 to 10% for GIPV preparations and was 14% for HIPV preparations. The GIPV preparations except those inactivated with 0.025% glutaraldehyde for 10 min (GIPV-A) were much less toxic than the HIPV preparations in the MWGT. The GIPV-A preparations did not pass the MWGT. The GIPV preparations were also much less toxic in HS and LPF tests than the HIPV preparation. The potency of GIPV preparations inactivated with 0.05% glutaraldehyde for 10 min (GIPV-D) was similar to that of HIPV preparations. The prolonged treatments with glutaraldehyde reduced the potency. The GIPV-D preparation with good potency and less toxicity was found to be inactivated with glutaraldehyde under optimal conditions. All the preparations were innocuous in the abnormal toxicity test.     

Potency variation of small-molecule chymase inhibitors across species

Chymases (EC 3.4.21.39) are mast cell serine proteinases that are variably expressed in different species and, in most cases, display either chymotryptic or elastolytic substrate specificity. Given that chymase inhibitors have emerged as potential therapeutic agents for treating various inflammatory, allergic, and cardiovascular disorders, it is important to understand interspecies differences of the enzymes as well as the behavior of inhibitors with them. We have expressed chymases from humans, macaques, dogs, sheep (MCP2 and MCP3), guinea pigs, and hamsters (HAM1 and HAM2) in baculovirus-infected insect cells. The enzymes were purified and characterized with kinetic constants by using chromogenic substrates. We evaluated in vitro the potency of five nonpeptide inhibitors, originally targeted against human chymase. The inhibitors exhibited remarkable cross-species variation of sensitivity, with the greatest potency observed against human and macaque chymases, with K_i values ranging from ∼0.4 to 72 nM. Compounds were 10-300-fold less potent, and in some instances ineffective, against chymases from the other species. The X-ray structure of one of the potent phosphinate inhibitors, JNJ-18054478, complexed with human chymase was solved at 1.8 Å resolution to further understand the binding mode. Subtle variations in the residues in the active site that are already known to influence chymase substrate specificity can also strongly affect the compound potency. The results are discussed in the context of selecting a suitable animal model to study compounds ultimately targeted for human chymase.     

The anti-inflammatory profile of fluticasone propionate

Fluticasone propionate is a new corticosteroid based on the androstane nucleus. It is more lipophilic than beclomethasone dipropionate (BDP) and budesonide, and binds more avidly to human lung tissue. It has an absolute affinity (K_D) of 0.5 nM for the glucocorticoid receptor and a relative receptor aflinity 1.5- and 3.0-times greater than that of beclomethasone-17-monopropionate (17-BMP) and budesonide, respectively. The rate of association with the receptor is faster and the rate of dissociation slower than with standard corticosteroids. As a result, the half-life of the corticosteroid-receptor complex is >10 h. Fluticasone propionate is also highly selective for the glucocorticoid receptor, with little or no activity at other steroid receptors. Pretreatment with fluticasone propionate signiflcantly inhibits the increase in mast cell numbers in the nasal mucosa of rats chronically exposed to toluene di-isocyanate (TDI), and suppresses TDI-induced mast cell degranulation. It is more potent in vitro than dexamethasone, BDP and budesonide in inhibiting anti-CD3-induced human T-lymphocyte proliferation, in attenuating tumour necrosis factor-α-induced endothelial cell adhesion molecule expression, and in increasing secretory leucocyte protease inhibitor levels in airway epithelial cells. It is also more potent and longer-acting than other corticosteroids in inhibiting oedema formation, interleukin-5 (IL-5)-induced blood eosinophilia, and IL-5- or platelet activating factor-stimulated eosinophil accumulation in the lung. Fluticasone propionate therefore has increased intrinsic glucocorticoid potency and high topical anti-inflammatory activity.     

Soman intoxication-induced changes in serum acute phase protein levels,corticosterone concentration and immunosuppressive potency of the serum

We have studied the effect of soman intoxication on serum acute phase reactants (APR) levels, and the relationship of the APR and corticosterone concentrations and the immunosuppressive activity of the serum. One day after the injection of 1.8 LD₅₀ soman the concentrations of ₂-macroglobulin (₂-MG) and ₁-acid glycoprotein (AGP) in the serum of antidote protected rats increased 4- and 7-fold, respectively, whereas those of hemopexin (Hx), haptoglobin (Hp) and cysteine protease inhibitor (CPI) were two to three times higher than in the controls. A similar magnitude of increase of serum acute phase reactants levels was observed when 0.3 LD₅₀ soman was administered at 24-h intervals over the 5-day period. The relationship of changes in the APR concentration, corticosterone level and immunosuppressive activity of the serum was also comparable to that observed in the acute phase response to tissue injury.     

Studies on the mammary tumor-inhibiting effects of diethylstilbestrol and its mono- and diphosphate

Summary Diethylstilbestrol (DES), diethylstilbestrol monophosphate (DES-MP) and diethylstilbestrol diphosphate (DES-DP) were tested for their estrogen receptor affinity, estrogenic potency and mammary tumor-inhibiting activity in vitro and in vivo. DES had a much higher receptor binding affinity than its mono-or diphosphate. All three compounds inhibited the growth of the hormone-dependent MCF-7 and hormone-independent MDA-MB 231 breast cancer line only at relatively high concentrations. The estrogenic potency in the immature mouse uterine weight test decreased in the order DES>DES-MPDES-DP. The hormone-dependent MXT mammary tumor of the mouse was inhibited by all three compounds at a dosage of 1.0 mg/kg per week. At a dose of 0.01 mg/kg, DES, DES-MP, and DES-DP stimulated the tumor growth. Thus, for the first time, a biphasic effect on tumor growth was demonstrated in intact mature animals. As the effects of all three compounds were similar in this assay, a cleavage of the phosphate groups is likely. A decrease in estrogenic potency concomitant with a retained antitumor effect of DES-MP and DES-DP compared to DES was not demonstrable in the mature mouse using the MXT assay, only in the uterotrophic test in the immature mouse.Dedicated to Professor Dietrich Schmähl on occasion of his 60th birthdaySupported by the Deutsche Forschungsgemeinschaft and by the Verband der Chemischen Industrie, Fonds der Chemischen Industrie. The authors thank Dr. Weigert, Asta-Werke AG, Degussa Pharma Gruppe, Bielefeld, FRG, for the analysis of DES-MP and DP     

Assessment of oestrogenic potency of chemicals used as growth promoter by in-vitro methods

Three in-vitro bioassays were used to compare the oestrogenic potency of chemicals used as growth promoter in beef cattle in certain non-European Union countries (17beta-oestradiol, alpha-zearalanol, testosterone, trenbolone, trenbolone acetate, melengestrol acetate) or found as food contaminant such as the mycotoxin zearalenone and some of their metabolites (17alpha-oestradiol, oestrone, 17alpha-epitestosterone, 19-nortestosterone, androstendione, zearalanone, alpha-zearalanol, beta-zearalanol, alpha-zearalenol, beta-zearalenol). The strong oestrogens 17alpha-ethinyl oestradiol and diethylstilboestrol were used as standards. The first bioassay was based on the activation of a reporter gene by oestrogens in recombinant yeast expressing human or rainbow trout oestrogen receptor. In the second bioassay, the vitellogenin gene induction of rainbow trout hepatocyte cultures was used as a biomarker for the exposure to oestrogens. The third bioassay was based on the alkaline phosphatase gene induction by oestrogens in the human endometrial Ishikawa cell line. The assessment of oestrogenic potency of these chemicals clearly demonstrates the strong oestrogenicity of the mycotoxin zearalenone and its metabolites and particularly alpha-zearalenol which was as potent as ethinyl oestradiol and diethylstilboestrol in the human endometrial Ishikawa cell line.     

高效液相色谱电化学检测法在硫酸阿奇霉素含量测定和有关物质概况分析上的应用

目的　建立硫酸阿奇霉素含量测定和有关物质概况分析的 HPL C电化学检测法。方法　采用 L ichro-CART1 2 5 - 4Aluspher RP- select B柱进行分离 ;HP1 0 4 9A型安培电化学检测器检测 ;最佳检测电势 +0 .6 V;流动相为磷酸二氢钾缓冲液 -乙腈 (2 1 30∶ 870 ) ,p H 1 1 .0± 0 .1 ;流速 1 .0 m L· min-1 ;柱温 5 0℃。结果　被测样品中明显检出多个杂质峰 ;硫酸阿奇霉素主峰的峰面积与进样量在 0 .0 2～ 1 .2 μg的范围内呈良好的线性关系 ,r =0 .9997。最低检测限为 1 ng;中间精密度试验日内差为 RSD 1 .1 % ;日间差为 RSD 0 .7%。结论　本法具有较高的灵敏度、精密度和专属性 ,适用于硫酸阿奇霉素含量测定以及有关物质的概况分析     

低分子肝素生物活性测定方法的比较研究

目的:对低分子肝素(low molecular weight heparin,LMWH)生物活性即抗活化10因子(抗-FXa)和抗活化2因子(抗-FⅡa)测定的不同方法进行比较与研究,建立国家标准。方法:(1)比较量反应平行线与标准曲线2种分析方法在发色底物的分光光度法即利用发色底物对 FXa 或 FⅡa 特异的405 nm 显色反应测定抗-FXa 或抗-FⅡa 效价的差异。(2)比较发色底物的分光光度法与血液凝固法(观察兔全血或兔血浆的凝结时间)测定 LMWH 的抗凝血酶(抗-FⅡa)效价的异同。结果:量反应平行线法比标准曲线法测定结果可靠、准确、精确;发色底物分光光度法与血液凝固法的实验结果相似,其差异无统计学意义(P>0.05),并且具有良好相关性(r=0.997 P<0.01和 r=0.976 P<0.01)。结论:对 LMWH 的抗-FXa 和抗-FⅡa 效价测定采用发色底物的分光光度法;并以量反应平行线法进行分析。     

Prediction of skin sensitization potency using machine learning approaches

The replacement of animal use in testing for regulatory classification of skin sensitizers is a priority for US federal agencies that use data from such testing. Machine learning models that classify substances as sensitizers or non‐sensitizers without using animal data have been developed and evaluated. Because some regulatory agencies require that sensitizers be further classified into potency categories, we developed statistical models to predict skin sensitization potency for murine local lymph node assay (LLNA) and human outcomes. Input variables for our models included six physicochemical properties and data from three non‐animal test methods: direct peptide reactivity assay; human cell line activation test; and KeratinoSens™ assay. Models were built to predict three potency categories using four machine learning approaches and were validated using external test sets and leave‐one‐out cross‐validation. A one‐tiered strategy modeled all three categories of response together while a two‐tiered strategy modeled sensitizer/non‐sensitizer responses and then classified the sensitizers as strong or weak sensitizers. The two‐tiered model using the support vector machine with all assay and physicochemical data inputs provided the best performance, yielding accuracy of 88% for prediction of LLNA outcomes (120 substances) and 81% for prediction of human test outcomes (87 substances). The best one‐tiered model predicted LLNA outcomes with 78% accuracy and human outcomes with 75% accuracy. By comparison, the LLNA predicts human potency categories with 69% accuracy (60 of 87 substances correctly categorized). These results suggest that computational models using non‐animal methods may provide valuable information for assessing skin sensitization potency. Copyright © 2017 John Wiley & Sons, Ltd.