In vitro Approaches for Determining Mechanisms of Toxicity and Carcinogenicity by Asbestos in the Gastrointestinal and Respiratory Tracts

Mossman, Brooke T.

doi:10.2307/3429628

Cited by 30 publications

(18 citation statements)

References 11 publications

(12 reference statements)

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“…Three different incubation times (5 min, 1 h, and 4 h) and concentrations up to 100 M were used to determine the phototoxicities of the compounds. After illumination, cell survival was determined 24 h later by a standard 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay (44). MTT is used as an indicator of metabolically active cells, in which a color reaction dependent on enzyme activity takes place in mitochondria, and this activity can be measured with an enzyme-linked immunosorbent assay reader (540 nm).…”

Section: Methodsmentioning

confidence: 99%

Photodynamic Effects of Novel XF Porphyrin Derivatives on Prokaryotic and Eukaryotic Cells

Maisch¹,

Bosl²,

Szeimies³

et al. 2005

Antimicrob Agents Chemother

211

138

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The worldwide rise in the rates of antibiotic resistance of bacteria underlines the need for alternative antibacterial agents. A promising approach to the killing of gram-positive antibiotic-resistant bacteria of the skin uses light in combination with a photosensitizer to induce a phototoxic reaction. Different concentrations (0 to 100 M) of porphyrin-based photosensitizers (CTP1, XF70, and XF73) and different incubation times (5 min, 1 h, and 4 h) were used to determine phototoxicity against two methicillin-resistant Staphylococcus aureus strains, one methicillin-sensitive S. aureus strain, one methicillin-resistant Staphylococcus epidermidis strain, one Escherichia coli strain, and human keratinocytes and fibroblasts. Incubation with 0.005 M XF70 or XF73, followed by illumination, yielded a 3-log 10 (>99.9%) decrease in the viable cell numbers of all staphylococcal strains, indicating that the XF drugs have high degrees of potency against gram-positive bacteria and also that the activities of these novel drugs are independent of the antibiotic resistance pattern of the staphylococci examined. CTP1 was less potent against the staphylococci under the same conditions. At 0.005 M, XF70 and XF73 demonstrated no toxicity toward fibroblasts or keratinocytes. No inactivation of E. coli was detected at this concentration. XF73 was confirmed to act via a reactive oxygen species from the results of studies with sodium azide (a quencher of singlet oxygen), which reduced the killing of both eukaryotic and prokaryotic cells. When a quencher of superoxide anion and the hydroxyl radical was used, cell killing was not inhibited. These results demonstrate that the porphyrin-based photosensitizers had concentration-dependent differences in their efficacies of killing of methicillin-resistant staphylococcal strains via reactive oxygen species without harming eukaryotic cells at the same concentrations.

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Section: Methodsmentioning

confidence: 99%

Photodynamic Effects of Novel XF Porphyrin Derivatives on Prokaryotic and Eukaryotic Cells

Maisch¹,

Bosl²,

Szeimies³

et al. 2005

Antimicrob Agents Chemother

211

138

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show abstract

“…The MTT assay (Mossman, 1983) was used to quantify neuron viability after axotomy. The injured and contralateral uninjured pleural ganglia were collected, desheathed, and incubated in 0.2 mg/ml MTT (Sigma, St. Louis, MO) dissolved in modified L-15 culture medium without phenol red.…”

Section: Methodsmentioning

confidence: 99%

Synaptogenesis Regulates Axotomy-Induced Activation of c-Jun-Activator Protein-1 Transcription

Sung

Schacher

et al. 2006

Journal of Neuroscience

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The activator protein-1 (AP1) transcription complex remains active for long periods after axotomy, but its activity diminishes during target contact. This raises the possibility that the function of this complex is regulated by the synaptic connections. Using Aplysia californica, we found that crushing peripheral nerves in vivo enhanced AP1 binding in the sensory neurons that lasted for weeks and then declined as regeneration was completed. The AP1 complex in Aplysia is a c-Jun homodimer. Its activation, after axotomy, is mediated by Aplysia c-Jun-N-terminal kinase (apJNK), which enters the nucleus of sensory neurons and phosphorylates c-Jun at Ser-73 (p73-c-Jun). Active AP1 in the sensory neurons did not mediate apoptosis and was not involved in the appearance of the long-term hyperexcitability that develops in these cells after axotomy, and blocking the activation of apJNK in vitro did not influence neurite outgrowth. In contrast, the levels of activated apJNK and p73-c-Jun declined markedly when sensory neurons formed synapses with motor neuron L7 in vitro. Furthermore, inhibiting the pathway accelerated synaptogenesis between sensory neurons and L7. These data suggest that positive and negative modulation of the JNK-c-Jun-AP1 pathway functions in alerting the nucleus to the loss and gain of synapses, respectively.

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“…Cell viability was assessed by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, as described by Mossman [23]. The MTT (Sigma, USA) solution at a final concentration of 500 lg/ml was added to the culture medium 4 h before the end of the treatment, and the reaction was stopped by the addition of 100 ll of dimethyl sulfoxide to the cell culture.…”

Section: Cytotoxicity Assaymentioning

confidence: 99%

Microbial transformation of the sesquiterpene lactone tagitinin C by the fungus Aspergillus terreus

Rocha

Pupo

Antonucci³

et al. 2012

Journal of Industrial Microbiology and Biotechnology

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The biotransformation of the sesquiterpene lactone tagitinin C by the fungus Aspergillus terreus MT 5.3 yielded a rare derivative that was elucidated by spectrometric methods. The fungus led to the formation of a different product through an unusual epoxidation reaction between C4 and C5, formation of a C3,C10 ether bridge, and a methoxylation of the C1 of tagitinin C. The chemical structure of the product, namely 1b-methoxy-3a-hydroxy-3,10b-4,5a-diepoxy-8b-isobutyroyloxygermacr-11(13)-en6a,12-olide, is the same as that of a derivative that was recently isolated from the flowers of a Brazilian population of Mexican sunflower (Tithonia diversifolia), which is the source of the substrate tagitinin C. The in vitro cytotoxic activity of the substrate and the biotransformed product were evaluated in HL-60 cells using an MTT assay, and both compounds were found to be cytotoxic. We show that soil fungi may be useful in the biotransformation of sesquiterpene lactones, thereby leading to unusual changes in their chemical structures that may preserve or alter their biological activities, and may also mimic plant biosynthetic pathways for production of secondary metabolites.

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In vitro Approaches for Determining Mechanisms of Toxicity and Carcinogenicity by Asbestos in the Gastrointestinal and Respiratory Tracts

Cited by 30 publications

References 11 publications

Photodynamic Effects of Novel XF Porphyrin Derivatives on Prokaryotic and Eukaryotic Cells

Photodynamic Effects of Novel XF Porphyrin Derivatives on Prokaryotic and Eukaryotic Cells

Synaptogenesis Regulates Axotomy-Induced Activation of c-Jun-Activator Protein-1 Transcription

Microbial transformation of the sesquiterpene lactone tagitinin C by the fungus Aspergillus terreus

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