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Hr Incubation (hr + incubation)
Selected AbstractsSemi-quantitative tests of cyanide in foods and excreta of Three Hapalemur species in MadagascarAMERICAN JOURNAL OF PRIMATOLOGY, Issue 1 2010Nayuta Yamashita Abstract Three sympatric Hapalemur species (H. g. griseus, H. aureus, and H. (Prolemur) simus) in Ranomafana National Park, Madagascar are known to eat bamboo food parts that contain cyanide. How these lemurs avoid cyanide poisoning remains unknown. In this study, we tested for the presence/absence of cyanide in bamboo lemur foods and excreta to (1) document patterns of cyanide consumption among species with respect to diet, (2) identify routes of elimination of cyanide from the gastrointestinal tract, and (3) determine whether cyanide is absorbed from the diet. We tested 102 food, urine, and fecal samples for hydrogen cyanide (HCN) during two "pre-dry" seasons (April 2006, May 2007) using commercially available Cyantesmo test strips. The test strips changed color in the presence of HCN, and we recorded color change on a scale of 0 (no change) to 5 (cobalt) at preset intervals with a final score taken at 24,hr. We detected cyanide in bamboo food parts and urine of all three Hapalemur species. Time to color change of the test strips ranged from almost instantaneous to >12,hr incubation. Of the foods tested, only bamboo contained cyanide, but results differed among bamboo species and plant parts of the same species. Specifically, branch shoot and culm pith of the giant bamboo produced strong, immediate reactions to the test paper, whereas parts of liana bamboos produced either weak or no color change. Cyanide was present in almost all urine samples but rarely in fecal samples. This suggests that dietary cyanide is absorbed in the gastrointestinal tract of the Hapalemur species and excreted, at least in part, by the kidneys. Samples from H. griseus exhibited lower, though still detectable, cyanide levels compared with H. simus and H. aureus. Differences among lemur species appear to be related to the specific bamboo parts consumed. Am. J. Primatol. 72:56,61, 2010. © 2009 Wiley-Liss, Inc. [source] Microsomal UDP-Glucuronyltransferase in Rat Liver: Oxidative ActivationBASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 6 2005Marķa Eugenia Letelier In this work, we characterize Fe3+/ascorbate-induced activation of UDPGT activity prior to solubilization with Triton X-100 and after the oxidation process provoked the solubilization of the enzyme. We observed a time-dependent increase in UDPGT activity up to 20 min. incubation of the microsomes with Fe3+/ascorbate (3-times); after 20 min. incubation, however, we observed a time-dependent decrease in this activity to basal levels after 4 hr incubation. Treatment of microsomes with 0.1% Triton X-100 (5 min.) lead to a similar increase in UDPGT activity; higher detergent concentrations produced a dose-dependent decrease in this activity to basal levels with 1% Triton X-100. Interestingly, UDPGT activity was susceptible to activation only when associated to microsomal membranes and the loss of activation correlated with the solubilization of this activity. UDPGT activation by either Fe3+/ascorbate or Triton X-100 was correlated with an increase in p -nitrophenol apparent Km and Vmax values. This activation was prevented or reversed by the reducing agents glutathione, cysteine or dithiothreitol when it was induced by the Fe3+/ascorbate. Furthermore, the latter provoked a significant decrease in microsomal thiol content, effect not observed after treatment with Triton X-100. Our results suggest that the main mechanism responsible for Fe3+/ascorbate-induced UDPGT activation is likely to be the promotion of protein sulfhydryl oxidation; this mechanism appears to be different from detergent-induced UDPGT activation. [source] Effects of tomato paste extracts on cell proliferation, cell-cycle arrest and apoptosis in LNCaP human prostate cancer cellsBIOFACTORS, Issue 2 2005Eun-Sun Hwang Abstract Since tomato consumption is associated with decreased risk of prostate cancer, cell proliferation, cell cycle progression and apoptosis by LNCaP human prostate cancer cells might elucidate action of tomatoes. To discover possible bioactive fractions of tomatoes, whole tomato paste and its water and hexane extract were used and biomarkers of carcinogenesis were measured. After 6, 24 and 48 hr of incubation, cells were harvested and determined cell growth. Tomato paste hexane extract inhibited cell proliferation by 33% compared to the control after 48 hr incubation. Whole tomato paste and its water extract showed only modest growth inhibition. Tomato paste hexane extract at 5 ,M lycopene increased G2/M-phase of the cell cycle from 13 to 28% and decreased S-phase cells from 45 to 29%. Apoptosis was observed at the 5 ,M hexane extract at the late stages during 24 and 48 hr treatment. Tomato, therefore, deserves study as a potential chemopreventive/chemotherapeutic agent. [source] Effects of cadmium on formation of the ventral body wall in chick embryos and their prevention by zinc pretreatmentBIRTH DEFECTS RESEARCH, Issue 2 2001Jennifer Thompson Background Cadmium (Cd) is an established experimental teratogen whose effects can be reversed by pretreatment with zinc. Mesodermal development is a frequently reported target for Cd teratogenicity. The aim of this study was to examine the mechanisms of Cd induced body wall defects in chick embryos. Methods Chick embryos in shell-less culture were treated with 50 ,l of cadmium acetate (8.9 × 10,5 M Cd2+) at 60-hr incubation (H.-H. stages 16,17). Controls received equimolar sodium acetate. Other embryos were treated with various concentrations of zinc acetate and then with Cd or NaAc 1 hrs later. Development was evaluated 48 hrs later. Resin-embedded 1-,m sections were examined at earlier stages. Results Cd caused embryolethality (35%), ventral body wall defect with malpositioned lower limbs (40%), and weight reduction in survivors. After 4-hr treatment with Cd, breakdown of junctions between peridermal cells with rounding up and desquamation occurred. Shape changes were also seen in the basal layer of the ectoderm. At 4 hr, cell death was evident in lateral plate mesoderm, somites, and neuroepithelium; the lateral plate mesoderm began to grow dorsally, carrying the attached limb buds with it. Zn pretreatment protected against the lethal, teratogenic, and growth-retarding effects of Cd, as well as ectodermal changes and cell death. Conclusions Cd disrupts peridermal cell adhesion and induces cell death in the mesoderm. This may result in abnormal growth of lateral plate mesoderm and in a body wall defect. Zn pretreatment prevents both the gross teratogenic effects and the cellular changes, most likely by competition with Cd. Teratology 64:87,97, 2001. © 2001 Wiley-Liss, Inc. [source] 4363: Cytostatic and cytotoxic effects of 5-fluorouracil on human corneal epithelial cells and keratocytesACTA OPHTHALMOLOGICA, Issue 2010E MIDENA Purpose To investigate the effects of different 5-Fluorouracil (5-FU) concentrations, exposure times and application techniques on in vitro cultured human corneal cells. Methods Human corneal epithelial cells (HCEC) and human corneal keratocytes (HCK) cultures were exposed to different 5-FU concentration (0.025% to 1%) and incubation times (single 5' to 2 hrs). The cytostatic effect was evaluated as ratio of inhibition of migration towards controls. The cytotoxic effect evaluation included both contrast phase microscopic observations, and viability measures performed using a MTT[3-(4,5-dimethylthiazo-2-yl)-2,5-diphenyltetrazolium bromide; thiazolyl blue] colorimetric assay. The results were expressed as ratio of optical density (OD) reduction 24 hrs after exposures. Results Cytostatic effect is time and dose dependent. Minimal inhibiting dose (ID50) was 0,55% after 1 hour incubation for HCEC; ID50 was 0,5% after 2 hrs incubation for HCK . A 100% inhibitory effect was never observed at any concentration or incubation interval. No cytotoxic changes were observed at 5-FU < 1%; 5-FU 1% showed time-dependent cytotoxic changes just in HCEC cultures. MTT analysis showed no OD reduction at 5-FU concentration < 1%, whereas 1% 5-FU showed OD reduction < 50% at any tested exposure time. HCEC showed higher reduction in OD than HCK. Conclusion 5-FU shows no definite signs of irreversible toxicity to normal cultured corneal epithelial and keratocyte cells at examined concentrations and exposure time. [source] | |||||||||||||