摘要:

AbstractBracken fem (Pteridiumspp.), one of the most abundant plants on the planet, is well known to cause cancer naturally in sheep and cattle. It contains, in some locations, extremely high concentrations of ptaquiloside which almost certainly is its major carcinogen. Ptaquiloside is transferred through milk. There is epidemiological evidence that the bracken carcinogen, in special situations, may cause cancer in man. Ptaquiloside and its animal models of carcinogenesis also offer good tools for the study of cancer. © 1995 Wiley‐Liss, I

ISSN:1056-9014    

DOI:10.1002/nt.2620030102

出版商:John Wiley&Sons, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe prevalence of exposure to aflatoxin, hepatitis B virus (HBV), and hepatitis C virus (HCV), three important risk factors for hepatocellular carcinoma, was examined in Guinea, West Africa. A total of 75 sera were collected from men living in the Kindia region of lower Guinea. The sera were analysed by immunoassay of aflatoxin covalently bound to serum albumin as a marker of aflatoxin exposure. Over 90% of the sera contained detectable adduct levels, the hishest level being 385 pg aflatoxin B1‐lysine equivalent per mg albumin. Eleven subjects (14.7%) were positive for hepatitis B surface antigen in the serum and these subjects had a tendency to have higher aflatoxin‐albumin adduct levels than the other subjects (mean level 70.4 pg/mg compared to 44.1 pg/mg), but the difference was not statistically significant (P = 0.23). Eight subjects were positive for antibodies to HCV antigens and, interestingly, seven of these were from one ethnic group, Mandinka (25% prevalence). These data demonstrate that all three exposures are prevalent in Guinea and that the prevalence of these risk factors is comparable to that observed in other countries in West Africa. It is now important to assess the public health impact of these exposures in this country. © 1995 Wiley‐Lis

ISSN:1056-9014    

DOI:10.1002/nt.2620030103

出版商:John Wiley&Sons, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractCultures of several isolates ofStachybotrys chartarumhave produced a series of cytotoxic macrocyclic trichothecenes including two newly characterized conseners: isosatratoxin G andS‐isosatratoxin H. Nine immunosuppressant phenylspirodrimanes (1–9) were isolated and characterized, the majority of which are newly reported compounds. © 1995 Wiley‐Lis

ISSN:1056-9014    

DOI:10.1002/nt.2620030104

出版商:John Wiley&Sons, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractA new toxic sesterterpene, namedfusaproliferin, was purified from corn kernel cultures (120 ms/kg dry culture) of a strain ofFusarium proliferatumisolated from com ear rot in northern Italy. The strain, designated ITEM‐1494, also produced fumonisin B., (1.500 mg/kg dry culture) and beauvericin (90 mg/kg dry culture), but not moniliformin. To monitor toxicity, the brine shrimp assay was used throughout the isolation procedure. Fusaproliferin had a molecular formula of C27H40O5, and it is the first sesterterpene isolated from aFusarium species. © 1995 Wiley‐Liss,

ISSN:1056-9014    

DOI:10.1002/nt.2620030105

出版商:John Wiley&Sons, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractExperiments were performed using an anaesthetised rat model to investigate the local inflammatory responses produced by intradermal injections of crude venom gland extracts from a number of Australian spiders, namely,Phonognatha graeffei, Delena cancerides, Isopeda montana, Badumna insignis, Lampona cylindrata, Steatoda grossa, S. capensisHann. All of the venom gland extracts tested, with the exception of that from S. capensis, produced increases in vascular permeability consistent with acute inflammatory responses. The responses primarily involved the activation of 5‐HT receptors, since they were markedly reduced by the nonselective 5‐HT1/5‐HT2‐receptor antagonist methiothepin. Some of the venoms caused liberation of endogenous mediators of inflammation, and some had components that acted directly on the vasculature to increase vascular permeability. Histamine appeared to have little if any role in the observed increases in vascular permeability following intradermal injection of the spider venoms. © 1995 Wiley

ISSN:1056-9014    

DOI:10.1002/nt.2620030106

出版商:John Wiley&Sons, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractA basic myotoxic protein was purified fromBothrops asper venom. Like other basicBothropsmyotoxins, myotoxin IV induces acute muscle damage after intramuscular injection in mice and disrupts negatively charged liposomes but not positively charged ones. Furthermore, this protein exerts a weak anticoagulant effect only at concentrations of 40 μg/ml or higher, and is devoid of phospholipase A2activity. Rabbit polyclonal antibodies toB. aspermyotoxin II, a related lysine‐49 isoform, cross‐react strongly with myotoxin IV by enzyme immunoassay, indicating a high degree of antigenic similarity between these two proteins. The fact that both toxins have similar amino acid compositions and amino‐terminal sequences, including leucine‐5 and glutamine‐11, 2 amino acid residues conserved in all lysine‐49 phospholipase A2variants purified, strongly suggests thatB. aspermyotoxin IV is a lysine‐49 phospholipase A2. © 1995

ISSN:1056-9014    

DOI:10.1002/nt.2620030107

出版商:John Wiley&Sons, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe in vivo genotoxic effects of the antitumor antibiotic, (−)‐CC‐1065, and its unnatural enantiomer, (−)‐CC‐1065, were investigated in two mouse models. These two compounds alkylate AT‐rich regions of double stranded DNA with distinct sequence selectivities.(+)‐CC‐1065 dose‐dependently increased the chromosomal aberration frequency in bone marrow cells of CD‐1 mice from 1.2 ± 0.8% in vehicle control animals to 5.0 ± 1.2%, 11.4 ± 3.9%, and 20.6 ± 2.3% 24 hours following single intravenous doses of 2, 4, and 8 μg/kg, respectively. (−)CC‐1065 was significantly less potent with a maximal response at 8 μg/kg approximately one‐third of that observed for (+)‐CC‐1065.(+)‐CC‐1065 induced a significant (P ± 0.05), three‐fold increase in the number of lung tumors/mouse in strain A/J mice from 0.27 ± 0.15 for vehicle control animals to 0.83 ± 0.15 24 weeks following a single intravenous dose of 8 μs/kg. This effect was paralleled by corresponding threefold increases in the percentage of mice with tumors and the percentage of mice with multiple tumors, compared to vehicle controls. (−)‐CC‐1065 at 8 μg/kg induced 0.67 ± 0.15 tumors/mouse and resulted in slightly smaller increases in the tumor incidence and multiple tumor incidence, compared to (+)‐CC‐1065.The above results demonstrate that single intravenous doses of (+)‐CC‐1065 and (−)‐CC‐1065 which cause chromosomal damage in CD‐1 mice also induce an increased incidence of lung tumors in A/J mice. (+)‐CC‐1065 may have a slightly greater genotoxic potential in vivo than its unnatural enantiomer. This may be attributable to differences in the DNA binding sequence selectivities of the two compounds. Furthermore, when compared on a μ‐moles/kg basis, (+)‐CC‐1065 is>7,000 × more potent than N‐ethyl‐N‐nitrosourea at inducing a

ISSN:1056-9014    

DOI:10.1002/nt.2620030108

出版商:John Wiley&Sons, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractA reliable and sensitive method for determination of hepatotoxic microcystins in complicated matrices by frit‐fast atom bombardment liquid chromatography/mass spectrometry (Frit‐FAB LC/MS) is described. Immonium ions of constituent amino acids, which were obtained together with molecular ion species by FAB mass spectral analysis of standard microcystins RR, YR, LR, and [D‐Asp3] and [Dha7]microcystins LR using flow injection system composed of Frit‐FAB probe, showed potential for reliable identification of microcystins by Frit‐FAB LC/MS. Frit‐FAB LC/MS using a microbore column provided not only the baseline separation of standard microcystins RR, YR, and LR but 200‐fold higher sensitivity than that using conventional column. Furthermore, when a selected ion monitoring (SIM) technique was used, the detection limits of microcystins RR, YR, and LR were 300, 350, and 400 pg, respectively, at a signal‐to‐noise ratio of 5:1, and calibration curves of each microcystin showed a linear relationship from 2 ng to 50 ng. Finally, identification and quantitative analyses of microcystins in water samples were carried out. © 19

ISSN:1056-9014    

DOI:10.1002/nt.2620030109

出版商:John Wiley&Sons, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractSix microcystins were identified in a laboratory culture of the cyanobacterium (blue‐sreen alga)Microcystis aeruginosaPCC 7813 using high‐performance liquid chromatography coupled with diode array detection (HPLG‐DAD) and mass spectrometry (LC‐MS). The toxins were purified and further characterized by amino acid analysis and tandem mass spectrometry (MS‐MS). The presence of the previously reported microcystin‐LR and microcystinly was confirmed. Two further microcystins were characterized as microcystin‐LW and microcystin‐LF. Another two toxins were partially characterized and are believed to be an analog of microcystin‐LR (molecular weight 1008) and microcystin‐LM (molecular weight 969). Natural bloom material ofM. aeruginosacollected from 2 reservoirs was found to have similar microcystin profiles using HPLC‐DAD and LC‐MS, indicating the widespread occurrence of these microcystin variants. In addition, the presence of 5 of the microcystins was confirmed in the rumen contents of a lamb by LC‐MS and LC‐MS‐MS, providing the first report of microcystins identified in an animal suspected of being poisoned by cyanobacterial hepatot

ISSN:1056-9014    

DOI:10.1002/nt.2620030110

出版商:John Wiley&Sons, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractTwo non‐protein amino acids ofLathyrus sativus, β‐(isoxazoline‐5‐on‐2‐yl)‐alanine (BIA) and its higher homologue α‐amino‐γ‐Cisoxazoline‐5‐on‐2‐yl)‐alanine (ACI) were tested for excitotoxic potential. BIA (0.5‐2.0 mM) but not ACI (2.0 mM) produced a concentration‐dependent neurodegeneration in mouse cortical explants. The neuronal damage was prevented by the prior and simultaneous application of 6‐cyano‐7‐nitroquinoxaline‐2,3‐dione (CNQX), indicating that it was mediated by non‐N‐methyl‐D‐aspartate type receptors. BIA (0,5‐2.0 mM) activated CNQX‐sensitive currents which were significantly smaller than those activated by 3‐N‐oxalyl‐L‐2,3‐diaminopropanoic acid (β‐ODAP) or α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazole‐propionic acid (AMPA) in the majority of neurons. In a small number of cells, BIA (2 mM) produced currents which were similar in amplitude to those activated by β‐ODAP (50 μM). These results suggest thatLathyrus sativusplants engineered to block the synthesis of β‐ODAP may accumulate a neurotoxic precurs

ISSN:1056-9014    

DOI:10.1002/nt.2620030111

出版商:John Wiley&Sons, Inc.    

年代:1995

数据来源: WILEY