Search results for "TOXICITY"
showing 10 items of 2261 documents
A novel cytotoxin from Clostridium difficile serogroup F is a functional hybrid between two other large clostridial cytotoxins.
1999
Abstract The large clostridial cytotoxins (LCTs) constitute a group of high molecular weight clostridial cytotoxins that inactivate cellular small GTP-binding proteins. We demonstrate that a novel LCT (TcdB-1470) from Clostridium difficile strain 1470 is a functional hybrid between “reference” TcdB-10463 andClostridium sordellii TcsL-1522. It bound to the same specific receptor as TcdB-10463 but glucosylated the same GTP-binding proteins as TcsL-1522. All three toxins had equal enzymatic potencies but were equally cytotoxic only when microinjected. When applied extracellularly TcdB-1470 and TcdB-10463 were considerably more potent cytotoxins than TcsL-1522. The small GTP-binding protein R-R…
Effects of sublethal levels of tributyltin chloride on a new toxicity test organism,Liza saliens (osteichthyes, mugilidae): a histological study
2006
The histopathological effects of 10−7 and 10−9M tributyltin(IV)chloride,TBTCl, solutions on different Liza saliens organs have been studied by light microscope. The fish were sacrificed after 3–4 h incubation in 10−7M TBTCl solution or after 15 days incubation in 10−9M solution. The observed histopathological changes were dose- and time-dependent. The 10−7M TBTCl concentration resulted in major damage to the gill epithelium, indicating that TBTCl primarily interfered with the respiration, osmoregulation, acid balance and nitrogenous waste excretion processes. After incubation in 10−9M TBTCl solution the fish lived 20 or more days, but many of the organs were altered. Thymus atrophy, reduced…
Iron-Catalyzed C−O Bond Activation: Opportunity for Sustainable Catalysis
2017
Oxygen-based electrophiles have emerged as some of the most valuable cross-coupling partners in organic synthesis due to several major strategic and environmental benefits, such as abundance and potential to avoid toxic halide waste. In this context, iron-catalyzed C-O activation/cross-coupling holds particular promise to achieve sustainable catalytic protocols due to its natural abundance, inherent low toxicity, and excellent economic and ecological profile. Recently, tremendous progress has been achieved in the development of new methods for functional-group-tolerant iron-catalyzed cross-coupling reactions by selective C-O cleavage. These methods establish highly attractive alternatives t…
Expanding the Variety of Zirconium‐based Inorganic Building Units for Metal–Organic Frameworks
2019
Two new zirconium-based metal-organic frameworks with the composition [Zr6 O4 (OH)4 (OAc)6 (BDC)3 ] (CAU-26) and [Zr5 O4 (OH)4 (OAc)4 (BDC)2 ] (CAU-27) are reported, which were synthesized from acetic acid, a rarely utilized but green and sustainable solvent (BDC2- : 1,4-benzenedicarboxylate). Structure determination aided by automated electron diffraction tomography revealed that CAU-26 is composed of layers of well-known {Zr6 O8 } clusters interconnected by terephthalate ions. In contrast CAU-27 exhibits a three-dimensional structure with a so far unknown type of one-dimensional inorganic building unit (IBU), which can be rationalized as condensed polyhedron-sharing chains of {Zr6 O8 } cl…
Nickel(II) inhibits the repair of O 6 -methylguanine in mammalian cells
1999
Nickel compounds are widespread carcinogens, and although only weakly mutagenic, interfere with nucleotide excision repair and with the repair of oxidative DNA base modifications. In the present study we investigated the effect of nickel(II) on the induction and repair of O6-methylguanine and N7-methylguanine after treatment with N-methyl-N-nitrosourea (MNU). We applied Chinese hamster ovary cells stably transfected with human O6-methylguanine-DNA methyltransferase (MGMT) cDNA (CHO-AT), and compared the results with the MGMT-deficient parental cell line. As determined by high-performance liquid chromatography/electrochemical detection (HPLC/ECD), there was a slight but mostly not significan…
Intra- and extra-cellular DNA damage by harmine and 9-methyl-harmine
2014
It is known that b-carbolines are able to produce photosensitized damage in cell-free DNA, but there is little information on their effects on cellular DNA. Therefore, we have analyzed the DNA damage produced by harmine and 9-methyl-harmine under UVA irradiation in V79 cells, together with the associated generation of micronuclei and photocytotoxicity. The results indicate that the most frequent photoproducts generated in the cellular DNA are modified purines such as 8-oxo-7,8-dihydroguanine. Only relatively few single-strand breaks were observed. CPDs were absent, although they were generated in cell-free DNA irradiated under the same conditions. The overall extent of DNA damage in the cel…
Ernährungsphysiologie erhitzter Fette: Langfristige Tierversuche
1974
Das Fette, die bei intensiver Beruhrung mit dem Luftsauerstoff langere Zeit auf hohere Temperaturen erhitzt worden sind, toxische Eigenschaften entwickeln, ist in vielen Laboratorien ubereinstimmend gezeigt worden. Je nach Schwere des Eingriffs reichen die bei Futterungsversuchen erhobenen Befunde von einer praktisch symptomenlosen Vertraglichkeit uber mehr oder minder schwere Wachstumsverzogerungen junger Tiere bis zu einer hohen Toxicitat wie starke Erhohung der Letalitatsrate und schweren anatomischen und histologischen Veranderungen der Organe. Fritierfette haben sich beim Einhalten der folgenden Bedingungen: Temperaturen nicht uber 180° C, Vermeiden jeder lokalen Uberhitzung durch einw…
Untersuchungen über die chronische Toxizität der Ascorbinsäure bei der Ratte
1963
Bei einer chronischen Verabreichung (10 Wochen) von 6,5 g Ascorbinsaure je kg Korpergewicht per os wurden bei der Ratte keine schadlichen Wirkungen beobachtet, selbst wenn die Tiere einer Stressituation (4 Wochen dauernde eiweisarme Ernahrung) unterworfen wurden. Tagesdosen von 27,3 g/kg Korpergewicht erwiesen sich als sicher toxisch. Die Mortalitatsrate betrug bei dieser Dosierung 77% innerhalb von 4 Wochen. Auf Grund dieser Versuche kann man als oberste Grenze der Vertraglichkeit bei chronischer Zufuhr 10 g Ascorbinsaure je kg Korpergewicht annehmen. Unter Zugrundelegung dieser Zahl ergibt sich fur die als wunschenswert erachtete Tagesdosis von 75 mg fur den Menschen eine Sicherheitsspann…
¿Es real el riesgo de osteoporosis y riesgo de fracturas con el uso crónico de inhibidores de la bomba de protones?
2011
Proton pump inhibitors (PPI) are one of the most widely used groups of drugs and their potential toxicity is periodically reviewed, emphasizing aspects originally considered secondary. The present review analyzes the physiological and pharmacological bases and the scarce clinical evidence for a potential association between the continued administration of PPI and the development of osteoporosis and bone fractures. Both disorders are clearly related to calcium homeostasis and are highly important in elderly patients due to their poor general prognosis and disabling consequences.
Killing of p53-deficient hepatoma cells by parvovirus H-1 and chemotherapeutics requires promyelocytic leukemia protein
2008
To evaluate the synergistic targeting and killing of human hepatocellular carcinoma (HCC) cells lacking p53 by the oncolytic autonomous parvovirus (PV) H-1 and chemotherapeutic agents and its dependence on functional promyelocytic leukemia protein (PML).The role of p53 and PML in regulating cytotoxicity and gene transfer mediated by wild-type (wt) PV H-1 were explored in two pairs of isogenic human hepatoma cell lines with different p53 status. Furthermore, H-1 PV infection was combined with cytostatic drug treatment.While the HCC cells with different p53 status studied were all susceptible to H-1 PV-induced apoptosis, the cytotoxicity of H-1 PV was more pronounced in p53-negative than in p…