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91.
Evaluation of the antimutagenic potential of chitosan oligosaccharide: Rec, Ames and Umu tests 总被引:4,自引:0,他引:4
Two types of chitosan oligosaccharides (COS), COS I (1-kDa < MW < 3-kDa) and COS II (3-kDa < MW < 5-kDa), were tested for antimutagenic activities against chemical mutagens using Umu gene expression, Ames, and Bacillus subtilis Rec mutagenicity tests. At the highest chitosan oligosaccharide dose (1 mg) tested, mutagenic activity of indirect-acting mutagen was inhibited by 50% in the Umu gene expression system and in the Ames test. Chitosan oligosaccharide (0.01, 0.1 and 1 mg) also suppressed 4-nitroquinoline-N-oxide (NQO)-induced mutagenicity in the B. subtilis Rec– assay. 相似文献
92.
Feledy J Caterson EJ Steger S Stal S Hollier L 《Plastic and reconstructive surgery》2004,114(7):1711-6; discussion 1717-8
Mandibular angle fractures are technically challenging, and a spectrum of techniques for treatment of these fractures has been proposed in the literature. Currently, fixation with one or two miniplates has become a widely accepted method of providing internal fixation and eliminating the need for postoperative maxillomandibular fixation. In this study, the utility of a single 2.0-mm matrix miniplate for mandibular angle fracture management was examined. In a laboratory biomechanical analysis, the overall stability of the single 2.0-mm matrix miniplate compared favorably with two 2.0-mm miniplates in a simulated fracture setting. The matrix miniplate demonstrated an overall better intrinsic stability, more resistance to out-of-plane fracture movement, and a higher load tolerance when motion out-of-plane was challenged. Clinically, the matrix miniplate performed well. In a series of 22 consecutive patients, there were no cases of nonunion, malunion, or plate failure. Two patients developed infection that was managed in both cases by drainage with maintenance of the miniplate. Both went on to full union. These results compare very favorably to previously published series using one or two miniplates. 相似文献
93.
Geiji-Bokryung-Hwan (GBH) was studied on antiplatelet activity in human platelet suspensions. GBH consists of the 5 herbs Cinnamomi Ramulus, Poria Cocos, Mountan Cortex Radicis, Paeoniae Radix, and Persicae Semen, which have been used in herbal medicine for thousands of years for atherosclerosis. The mechanism involved in the antiplatelet activity of GBH in human platelet suspensions was investigated. GBH inhibited platelet aggregation and Ca2+ mobilization in a concentration-dependent manner without increasing intracellular cyclic AMP and cyclic GMP. GBH had no inhibitory effect on thromboxane B2 (TXB2) production in cell-free systems. Collagen-related peptide (CRP)-induced Ca2+ mobilization is regulated by phospholipase C-2 (PLC-gamma2) activation. We evaluated the effect of GBH on tyrosine phosphorylation of PLC-gamma2 and the production of inositol-1,4,5-trisphosphate (IP3). GBH at concentrations that inhibited platelet aggregation and Ca2+ mobilization had no effects on tyrosine phosphorylation of PLC-gamma2 or on the formation of IP3 induced by CRP. Similar results were obtained with thrombin-induced platelet activation. GBH inhibited platelet aggregation and Ca2+ mobilization induced by thrombin without affecting the production of IP3. We then evaluated the effect of GBH on the binding of IP3 to its receptor. GBH at high concentrations partially blocked the binding of IP3 to its receptor. Therefore, the results suggested that GBH suppresses Ca2+ mobilization at a step distal to IP3 formation. GBH may provide a good tool for investigating Ca2+ mobilization. 相似文献
94.
Park TH Choi KW Park CS Lee SB Kang HY Shon KJ Park JS Cha J 《Applied microbiology and biotechnology》2005,69(4):411-422
The gene encoding β-glucosidase of the marine hyperthermophilic eubacterium Thermotoga neapolitana (bglA) was subcloned and expressed in Escherichia coli. The recombinant BglA (rBglA) was efficiently purified by heat treatment at 75°C, and a Ni-NTA affinity chromatography and its molecular mass were determined to be 56.2 kDa by mass spectrometry (MS). At 100°C, the enzyme showed more than 94% of its optimal activity. The half-life of the enzyme was 3.6 h and 12 min at 100 and 105°C, respectively. rBglA was active toward artificial (p-nitrophenyl β-d-glucoside) and natural substrates (cellobiose and lactose). The enzyme also exhibited activity with positional isomers of cellobiose: sophorose, laminaribiose, and gentiobiose. Kinetic studies of the enzyme revealed that the enzyme showed biphasic behavior with p-nitrophenyl β-d-glucoside as the substrate. Whereas metal ions did not show any significant effect on its activity, dithiothreitol and β-mercaptoethanol markedly increased enzymatic activity. When arbutin and cellobiose were used as an acceptor and a donor, respectively, three distinct intermolecular transfer products were found by thin-layer chromatography and recycling preparative high-performance liquid chromatography. Structural analysis of three arbutin transfer products by MS and nuclear magnetic resonance indicated that glucose from cellobiose was transferred to the C-3, C-4, and C-6 in the glucose unit of acceptor, respectively. 相似文献
95.
Centrosomes are the main microtubule‐organizing centers of animal cells. Although centrosome aberrations are common in tumors, their consequences remain subject to debate. Here, we studied the impact of structural centrosome aberrations, induced by deregulated expression of ninein‐like protein (NLP), on epithelial spheres grown in Matrigel matrices. We demonstrate that NLP‐induced structural centrosome aberrations trigger the escape (“budding”) of living cells from epithelia. Remarkably, all cells disseminating into the matrix were undergoing mitosis. This invasive behavior reflects a novel mechanism that depends on the acquisition of two distinct properties. First, NLP‐induced centrosome aberrations trigger a re‐organization of the cytoskeleton, which stabilizes microtubules and weakens E‐cadherin junctions during mitosis. Second, atomic force microscopy reveals that cells harboring these centrosome aberrations display increased stiffness. As a consequence, mitotic cells are pushed out of mosaic epithelia, particularly if they lack centrosome aberrations. We conclude that centrosome aberrations can trigger cell dissemination through a novel, non‐cell‐autonomous mechanism, raising the prospect that centrosome aberrations contribute to the dissemination of metastatic cells harboring normal centrosomes. 相似文献
96.
Sterigmatocystin (STG) is a toxic metabolite produced by severalAspergillus species. Because of its toxic and carcinogenic properties the occurrence of STG in food is considered to represent a potential
hazard to man. The present study was designed to investigate following points:
相似文献
1 | A survey of STG incidence in Ras cheese on local markets. Ras cheese samples were collected from Cairo, Giza and Kalubia governorates. Thirty five percent of the samples contained the toxin with a mean value of 22.23 μg /kg |
2 | Fate of STG contaminating milk during Ras cheese processing. Milk was artificially contaminated with 125 μg/kg and processed into Ras cheese. Eighty percent of the toxin was distributed into the curd and 20% into the whey. Cheese ripening effected toxin content and the effect was temperature dependent. At 6°C: toxin concentration was slightly affected; at 20°C the toxin was reduced by 16% after 90 days when low toxin concentration was used. |
3 | Formation of STG byA versicolor mold on Ras cheese. Ras cheese blocks were contaminated with spores of the mold. Toxin production started after 45 days of ripening and reached a maximum at 90 days and then declined. Cow’s milk favoured toxin production over buffaloe’s. Aged cheese inhibited toxin production. |
97.
98.
99.
Ju Jung-Hyun Oh Baek-Rock Heo Sun-Yeon Lee Young-Uk Shon Jung-hoon Kim Chul-Ho Kim Young-Min Seo Jeong-Woo Hong Won-Kyung 《Bioprocess and biosystems engineering》2020,43(1):33-43
Bioprocess and Biosystems Engineering - In this study, to produce adipic acid, mutant strains of Candida tropicalis KCTC 7212 deficient of AOX genes encoding acyl-CoA oxidases which are important... 相似文献
100.
Gene conversion and natural selection in the evolution of X-linked color vision genes in higher primates 总被引:2,自引:1,他引:1
During higher primate evolution, gene conversion seems to have occurred
often between the red and green photo-pigment genes, which are tandemly
linked on the X chromosome. To understand this phenomenon better, intron 4
sequences of the red and green pigment genes of a male human (an Asian
Indian), a male chimpanzee, and a male baboon were amplified by PCR and
sequenced. The data show that the intron 4 sequences between the two genes
have been strongly or completely homogenized in the three species studied.
Apparently recent gene conversion events have occurred in introns 4 of the
red and green pigment genes in humans and chimpanzees. Two or more
conversion events may have occurred at different times in introns 4 of the
two pigment genes in baboons. The divergence between the two genes is
significantly lower in intron 4 than in exons 4 and 5 in each species,
contrary to the usual situation that introns evolve faster than exons. It
is most likely that strong natural selection for maintaining the distinct
functions of exons 4 and 5 of the red and green pigment genes has acted
against sequence homogenization of these exons.
相似文献