Reducing nitrosamine contamination in cutting fluids

In simulated metalworking coolants that contained both nitrite and di- or triethanolamine at pH 9, N-nitrosodiethanolamine formed at an initial rate of 11 or 6 ppm/wk, respectively. This rate was increased on heating the fluids, on acidification or by the addition of paraformaldehyde, 1,3,5-trimethylhexahydro-s-triazine, ferricyanide or ferric ethylenediaminetetraacetate. N-Nitrosodiethanolamine also formed when nitrite-free coolants containing either of the two amines above were exposed to nitric oxide in air. No nitrosamines were detected in fluids containing primary amines in place of the secondary and tertiary amines, except that N-nitrosooxazolidine was formed in the fluid containing monoethanolamine after addition of formaldehyde-releasing agents, and N-nitrosodiethanolamine and N-nitrosomorpholine were found in fluid containing diglycolamine (HOCH2CH2OCH2CH2NH2) after the fluid was heated at 100 degrees C for 48 hr. These data suggest several steps by which nitrosamine formation in commercial cutting fluids might be substantially reduced: avoiding acid-splitting as a disposal procedure; removing nitrite from the fluid and/or scavenging adventitious nitrosating agents; avoiding unnecessary heating; adding preservatives to the diluted fluid rather than to the commercial concentrate; replacing inherently nitrosatable amine additives by substitutes which are resistant to nitrosamine formation; minimizing concentrations of catalytically active metal complexes.     

Novel chemiluminescence-inducing cocktails,part II: Measurement of the anti-oxidant capacity of vitamins,thiols, body fluids,alcoholic beverages and edible oils

Using two luminescence-inducing cocktails, two distinct patterns of inhibition of light by different anti-oxidants have been identified, comprising Group A, in which a complete inhibition of light emission which is then followed by re-emergence of light, forming apparent S-shaped curves or similar shapes. This light pattern is induced by the “classical” anti-oxidants, ascorbate, vitamin E, uric acid, thiols, deferoxamine, as well as by anti-oxidant agents present in plasma, saliva, urine and in extracts derived from black coffee, and Group B, in which a gradually emerging “mound”-shaped pattern of light was seen with extracts from the Tibetan plant mixture PADMA-28, elderberry (Sambucol), grape seeds, green and black teas, apple, parsimony, red wines, edible oils and SOD. While the results with the Group A agents point to the presence of probably a single, major, anti-oxidants relatively sensitive to oxidation, Group B agents probably include a mixture of anti-oxidants which are more resistant to oxidation. It was also shown that agents from Group B could protect agents from Group A against consumption by the oxidants generated by the cocktails. It is proposed that these simple to use cocktails which probably generate a multiplicity of oxidants mimicking those generated by activated phagocytes, can rapidly assess the total anti-oxidant capacities (TAOC) in body fluids derived from patients suffering of excessive oxidative stress. Also, this technique may be useful in determining the content of dietary anti-oxidants recommended as supplements to enhance the resistance against excessive oxidation of lipids.     

Effects of K+-channel blockers on A1-adenosine receptor-mediated negative inotropy and chronotropy of guinea-pig isolated left and right atria

Adenosine has previously been shown to stimulate K(+)-efflux and to block L-type calcium channels in atrial myocytes. The aim of the present study was to evaluate the contribution of K(+)-channels in the development of the negative inotropic and chronotropic responses to adenosine agonists in guinea-pig left and right atria, respectively. Tetraethylammonium (TEA) potentiated the negative inotropic and chronotropic responses to R-(-)-N6-(2-phenyl-isopropyl)-adenosine (R-PIA), seen as leftward shifts of the concentration-response curves. Glibenclamide had no effect on the negative inotropic response to R-PIA but increased the rate of onset of the negative chronotropic response in right atria. 4-Aminopyridine (4-AP, 10 mM), potentiated the left atrial inotropic responses to R-PIA, seen as a leftward shift of the concentration-response curve, but slowed the speed of onset of the response to a single concentration (10(-6) M) of R-PIA. This reduction in speed of onset of the response can explain the differences in effects of 4-AP on concentration-response curves reported here and previously. In the right atria, 4-AP (10 mM) inhibited the negative chronotropic responses to R-PIA, seen as a rightward shift of the concentration-response curve and reduction of the maximum response. 4-AP also slowed the onset of the right atrial rate response to R-PIA. These results support the theory that K(+)-efflux plays only a minor role in the negative inotropic responses of guinea-pig left atria to R-PIA. This apparently controls the speed of onset of the response. The negative chronotropic response of guinea-pig right atria to R-PIA appears to be much more dependent upon K(+)-efflux than for the negative inotropic response of the left atria.     

Monoliths with chiral surface functionalization for enantioselective capillary electrochromatography

The state-of-the-art in CEC enantiomer separations with monolithic capillary columns is comprehensively reviewed. The various types of monolithic columns comprising in situ organic polymer monoliths, molecularly imprinted polymer (MIP) monoliths, silica monoliths and monoliths made from particles are discussed with a focus on materials’ synthesis, chemistry and properties as well as column aspects. Monolithic MIP-type porous layer open-tubular (PLOT) columns are treated herein as well. From this survey of the literature, the authors come to the conclusion that monolithic silica capillaries appear to become the preferred column type for CEC enantiomer separations of low-molecular drugs and other chiral pharmaceuticals or chemicals.     

Thin endoscope-assisted endoscopic submucosal dissection for large colorectal tumors (with videos)

BACKGROUND: Endoscopic submucosal dissection (ESD) enables direct submucosal dissection so even large early stage GI tumors can be resected en bloc. Colorectal ESD is technically more difficult, however, and there is an increased risk of complications such as perforation and bleeding compared with gastric ESD. As a result, further refinements are required in this procedure. OBJECTIVE: Our purpose was to evaluate thin endoscope-assisted (TEA) ESD, a new traction system for improving submucosal cutting line visualization. DESIGN: Case series. SETTING: Okayama University Hospital. MAIN OUTCOME MEASUREMENTS: Efficacy and safety of the TEA-ESD procedure. RESULTS: Three cases of large, flat, elevated colorectal tumors (laterally spreading tumors) in the rectum and rectosigmoid colon were safely and successfully removed en bloc without complications. Total procedure times were 3 hours, 40 minutes, and 30 minutes with resected specimens measuring 70 x 68 mm, 38 x 35 mm, and 30 x 20 mm, respectively. LIMITATIONS: TEA-ESD was performed in only the rectum and rectosigmoid colon. CONCLUSIONS: This limited case series demonstrated that large laterally spreading tumors in the rectum and rectosigmoid colon could be safely resected en bloc with TEA-ESD.     

The anti-hypertensive effect of Danshen (Salvia miltiorrhiza) and Gegen (Pueraria lobata) formula in rats and its underlying mechanisms of vasorelaxation

Ethnopharmacological relevance

Radix Salviae miltiorrhizae (Danshen) and Radix Puerariae lobatae (Gegen) have long been used in traditional Chinese Medicine and serve as the principal herbs in treating cardiovascular disease.

Aims of the study

In the present study, an aqueous extract comprising Danshen and Gegen in the ratio of 7:3 (DG) was investigated for its anti-hypertension in vivo and vasodilative activities ex vivo.

Materials and methods

The anti-hypertensive effect of DG extract was investigated in spontaneously hypertensive rat (SHR) by measuring systolic blood pressure (SBP). Oral administration of DG extract was started at age of 6 weeks and 14 weeks for the preventive and therapeutic studies, respectively. Blood pressure was measured by tail-cuff method biweekly for 12 weeks. The ex vivo vasodilative activities of DG extract, its dependency on endothelium and the involvement of nitric oxide, prostacyclin and potassium channels were investigated using isolated rat aorta ring in organ bath.

Results

For in vivo study, systolic blood pressure was significantly reduced in DG extract-treated groups (90.2 and 300 mg/kg) as compared with the SHR control in both preventive and therapeutic studies. However, DG extract was unable to suppress or delay the onset of hypertension in the preventive study. For ex vivo study, the results showed that DG extract induced a concentration-dependent relaxation in aorta and persisted response was observed with the removal of endothelium. Besides, pretreatment with a non-selective potassium channel inhibitor tetraethylammonium (TEA) also significantly inhibited DG extract-induced vasodilation. Further investigations on specific potassium channel blockers revealed that ATP-sensitive potassium (K_ATP) channel inhibitor glibenclamide, inward rectifier potassium (Kir) inhibitor barium chloride and voltage-dependent potassium (K_v) channel inhibitor 4-aminopyridine, but not BK_Ca channel inhibitor iberiotoxin, exerted significant inhibition on DG extract-induced vasodilation.

Conclusions

The results of in vivo SHR animal model suggested that DG aqueous extract possessed blood pressure lowering effect on both pre- and post-hypertensive rats, which could be explained by its endothelium-independent vasodilation via the opening of K_ATP, Kir and K_v channels.     

In vivo and in vitro studies of anticancer actions of alpha-TEA for human prostate cancer cells

BACKGROUND: Vitamin E analog, 2,5,7,8-tetramethyl-2R-(4R,8R, 12-trimethyltridecyl) chroman-6-yloxyacetic acid, referred to as alpha-TEA induces apoptosis in a variety of human cancer cells in cell culture and reduces tumor burden and metastases in preclinical animal models of breast and ovarian cancer. The goal of this study was to determine in vivo anticancer efficacy of alpha-TEA against human prostate cancer cells and identify mechanisms of action. METHODS: A PC-3-GFP xenograft model was used to assess the effects of alpha-TEA formulated in liposomes and administered orally on tumor burden and metastases. Tumor tissue was examined by immunohistochemical staining for percentage of cells undergoing apoptosis by TUNEL or cell proliferation by Ki-67. In vitro analyses of mechanisms employed western immunoblotting to examine effects of alpha-TEA-treatments in LNCaP and PC-3-GFP cells on levels of pro-survival and pro-death factors. Functional significance was determined using ectopically expressed constitutively active forms, inhibitors, or siRNA. RESULTS: alpha-TEA significantly reduced tumor burden and metastases, increased apoptosis and decreased proliferation of tumor cells (P < 0.05). alpha-TEA treatment of both LNCaP and PC-3-GFP cells in vitro reduced levels of pAkt1, pAkt2; FOXO1, c-FLIP(L) and survivin. Constitutively active Akt1, Akt2, c-FLIP or survivin reduced alpha-TEA-induced apoptosis. PI3K inhibitor enhanced apoptosis. Constitutively active FOXO1 enhanced alpha-TEA induced Fas ligand expression; whereas, FOXO1 siRNA reduced alpha-TEA induced Fas ligand expression. CONCLUSIONS: alpha-TEA is an effective anticancer agent for human prostate cancer cells. Downregulation of pro-survival and upregulation of pro-death factors play roles in alpha-TEA-induced apoptosis.     

Critical roles for JNK, c-Jun, and Fas/FasL-Signaling in vitamin E analog-induced apoptosis in human prostate cancer cells

BACKGROUND: Alpha-tocopherol ether-linked acetic acid (alpha-TEA), an analog of vitamin E (RRR-alpha-tocopherol), is a potent pro-apoptotic agent for human cancer cells in vivo and in vitro. METHODS: alpha-TEA-induced apoptosis was investigated in LNCaP and PC-3 human prostate cancer cells. Apoptosis was measured by DAPI-staining and FACS analyses of the sub-G1 fraction. Signaling molecules involved in apoptosis were measured by Western immunoblot analyses with or without prior immunoprecipitation, FACS analyses of cell surface membrane expression, RT-PCR analyses of mRNA levels, and chromatin immunoprecipitation. Functional significance was determined using siRNAs, dominant negative mutant, chemical inhibitor, or neutralizing antibody. RESULTS: Alpha-TEA treatment increased Fas and Fas ligand mRNA and protein levels; as well as, levels of cell surface membrane Fas in both cell lines. Blockage of Fas signaling attenuated alpha-TEA-induced apoptosis. alpha-TEA treatment also produced prolonged, elevated levels of activated (phosphorylated) c-Jun N-terminal kinase (JNK) and its substrate c-Jun, both of which were demonstrated to be necessary for alpha-TEA-induced apoptosis. Chromatin immunoprecipitation results showed binding of c-Jun to the promoters of both Fas and FasL in alpha-TEA treated cells. Investigations of alpha-TEA-triggered apoptosis showed dual signaling from Fas with essential roles for both FADD and Daxx with FADD initiating the classical pathway mediated by caspase-8 activation and Daxx initiating an alternate pathway involving activation of JNK, c-Jun, and increased levels of Fas and FasL. CONCLUSIONS: Collectively, data support critical roles for JNK, c-Jun, and dual signaling from Fas/FasL via FADD and Daxx in alpha-TEA-induced apoptosis of human prostate cancer cells.     

Probing the substrate specificity of the ergothioneine transporter with methimazole, hercynine, and organic cations

Recently, we have identified the ergothioneine (ET) transporter ETT (gene symbol SLC22A4). Much interest in human ETT has been generated by case-control studies that suggest an association of polymorphisms in the SLC22A4 gene with susceptibility to chronic inflammatory diseases. ETT was originally designated a multispecific novel organic cation transporter (OCTN1). Here we reinvestigated, based on stably transfected 293 cells and with ET as reference substrate, uptake of quinidine, verapamil, and pyrilamine. ETT from human robustly catalyzed transport of ET (68micfrol/(minmgprotein)), but no transport of organic cations was discernible. With ET as substrate, ETT was relatively resistant to inhibition by selected drugs; the most potent inhibitor was verapamil (K(i)=11micromol/l). The natural compound hercynine and antithyroid drug methimazole are related in structure to ET. However, efficiency of ETT-mediated transport of methimazole (K(i)=7.5mmol/l) was 130-fold lower, and transport of hercynine (K(i)=1.4mmol/l) was 25-fold lower than transport of ET. ETT from mouse, upon expression in 293 cells, catalyzed high affinity, sodium-driven uptake of ET very similar to ETT from human. Additional real-time PCR experiments based on 16 human tissues revealed ETT mRNA levels considerably lower than in bone marrow. Our experiments establish that ETT is highly specific for its physiological substrate ergothioneine. ETT is not a cationic drug transporter, and it does not have high affinity for organic cation inhibitors. Detection of ETT mRNA or protein can therefore be utilized as a specific molecular marker of intracellular ET activity.     

三羟异黄酮对大鼠海马CA1区神经元自发放电的影响

目的研究三羟异黄酮（genistein，GST）对静息状态下的海马脑片神经元活动的影响。方法应用细胞外记录单位放电技术。结果（1）在48个CA1区神经元放电单位给予GST（10，50，100μmol／L）2min，有46个放电单位（95．83％）放电频率明显降低，且呈剂量依赖性；（2）在9个CA1区神经元放电单位上，GST（50μmol／L）的抑制效应可被G蛋白激活的内向整流型钾通道（Gprotein—coupled inwardly rectifying K^＋channels，GIRK）阻断剂（tetraethylammonium，TEA）1mmol／L完全阻断；（3）10个放电单位灌流一氧化氮合酶抑制剂（N^G-nitro—L—arginine methyl ester，L—NAME）50μmol／L，有9个单位（90．0％）放电明显增加，在此基础上灌流GST（50μmol／L）2min，放电被抑制；（4）预先用0．2mmol／L的L—glutamate（L—Glu）灌流海马脑片，11个放电单位放电频率明显增加，表现为癫痫样放电，在此基础上灌流GST（50μmol／L）2min，其癫痫样放电被抑制。结论GST可抑制海马神经元自发放电，并可抑制由L—NAME和L—glutamate诱发的神经元放电。提示GST对中枢神经元通过降低其活动而具有一定程度的保护作用，这种作用与钾电流有关，似与其激动GIRK促进K^＋外流引起细胞膜超极化以及NO产生增加有关。