Strategies for the follow-up of positive results in the in vitro genotoxicity assays-An international collaborative initiative

2010 ◽  
Vol 52 (3) ◽  
pp. 174-176 ◽  
Author(s):  
B. Bhaskar Gollapudi ◽  
Véronique Thybaud ◽  
James H. Kim ◽  
Michael Holsapple
Keyword(s):  
International Collaborative ◽  
Positive Results ◽  
Collaborative Initiative ◽  
In Vitro Genotoxicity

scholarly journals Validation of the 3D reconstructed human skin Comet assay, an animal-free alternative for following-up positive results from standard in vitro genotoxicity assays

Mutagenesis ◽  
2020 ◽  
Author(s):  
Stefan Pfuhler ◽  
Ralph Pirow ◽  
Thomas R Downs ◽  
Andrea Haase ◽  
Nicola Hewitt ◽  
...  
Keyword(s):  
Comet Assay ◽  
Human Skin ◽  
Assessment Process ◽  
Predictive Capacity ◽  
Industrial Sectors ◽  
Positive Results ◽  
In Vitro Genotoxicity

Abstract As part of the safety assessment process, all industrial sectors employ genotoxicity test batteries, starting with well-established in vitro assays. However, these batteries have limited predictive capacity for the in vivo situation, which may result in unnecessary follow-up in vivo testing or the loss of promising substances where animal tests are prohibited or not desired. To address this, a project involving regulators, academia and industry was established to develop and validate in vitro human skin-based genotoxicity assays for topically exposed substances, such as cosmetics ingredients. Here, we describe the validation of the 3D reconstructed skin (RS) Comet assay. In this multicenter study, chemicals were applied topically three times to the skin over 48 h. Isolated keratinocytes and fibroblasts were transferred to slides before electrophoresis and the resulting comet formation was recorded as % tail DNA. Before decoding, results of the validation exercise for 32 substances were evaluated by an independent statistician. There was a high predictive capacity of this assay when compared to in vivo outcomes, with a sensitivity of 77 (80)%, a specificity of 88 (97)% and an overall accuracy of 83 (92)%. The numbers reflect the calls of the performing laboratories in the coded phase, whereas those in parenthesis reflect calls according to the agreed evaluation criteria. Intra- and inter-laboratory reproducibility was also very good, with a concordance of 93 and 88%, respectively. These results generated with the Phenion® Full-Thickness skin model demonstrate its suitability for this assay, with reproducibly low background DNA damage and sufficient metabolic capacity to activate pro-mutagens. The validation outcome supports the use of the RS Comet assay to follow up positive results from standard in vitro genotoxicity assays when the expected route of exposure is dermal. Based on the available data, the assay was accepted recently into the OECD test guideline development program.

How to reduce false positive results when undertaking in vitro genotoxicity testing and thus avoid unnecessary follow-up animal tests: Report of an ECVAM Workshop

2007 ◽  
Vol 628 (1) ◽  
pp. 31-55 ◽  
Author(s):  
David Kirkland ◽  
Stefan Pfuhler ◽  
David Tweats ◽  
Marilyn Aardema ◽  
Raffaella Corvi ◽  
...  
Keyword(s):  
False Positive ◽  
Genotoxicity Testing ◽  
Positive Results ◽  
Animal Tests ◽  
In Vitro Genotoxicity

Relevance and follow-up of positive results in in vitro genetic toxicity assays: An ILSI-HESI initiative

2007 ◽  
Vol 633 (2) ◽  
pp. 67-79 ◽  
Author(s):  
Véronique Thybaud ◽  
Marilyn Aardema ◽  
Daniel Casciano ◽  
Vicki Dellarco ◽  
Michelle R. Embry ◽  
...  
Keyword(s):  
Genetic Toxicity ◽  
Positive Results

Impact of positive results from in vitro genotoxicity

2007 ◽  
Vol 172 ◽  
pp. S24-S25
Author(s):  
Véronique Thybaud
Keyword(s):  
Positive Results ◽  
In Vitro Genotoxicity

Hydroxyurea chemotherapy in the treatment of meningiomas

2007 ◽  
Vol 23 (4) ◽  
pp. E11 ◽  
Author(s):  
Herbert B. Newton
Keyword(s):  
Clinical Trials ◽  
Ribonucleotide Reductase ◽  
External Beam Radiotherapy ◽  
Slow Growing ◽  
Positive Results ◽  
Modest Activity

✓ Meningiomas are slow growing, extraaxial tumors that derive from the arachnoidal cap cells of the meninges. Resection remains the main modality of treatment and can be curative in some cases. External-beam radiotherapy and radiosurgery can benefit selected patients. The role of chemotherapy continues to be defined, but should be considered for patients with inoperable or frequently recurring meningiomas. Hydroxyurea, an inhibitor of ribonucleotide reductase, is one of the most active agents and is known to induce apoptosis in meningioma cells in vitro and in mouse xenografts. Results of preliminary clinical studies suggest that hydroxyurea has modest activity against recurrent and inoperable meningiomas, and can induce long term stabilization in some patients. However, the results are conflicting and a few clinical trials did not show positive results. Further clinical trials with larger patient cohorts and longer follow-up periods will be necessary to confirm the activity of hydroxyurea.

Retrospective study of false positive results in in vitro genotoxicity studies

2013 ◽  
Vol 221 ◽  
pp. S131
Author(s):  
Hana Hofman-Hüther
Keyword(s):  
Retrospective Study ◽  
False Positive ◽  
Positive Results ◽  
In Vitro Genotoxicity

Follow-up actions from positive results of in vitro genetic toxicity testing

2010 ◽  
Vol 52 (3) ◽  
pp. 177-204 ◽  
Author(s):  
Kerry L. Dearfield ◽  
Véronique Thybaud ◽  
Michael C. Cimino ◽  
Laura Custer ◽  
Andreas Czich ◽  
...  
Keyword(s):  
Toxicity Testing ◽  
Genetic Toxicity ◽  
Positive Results

scholarly journals TO010A NEW IMMUN-TOXICOLOGICAL TEST TO DETECT POLYSULFONE HYPERSENSITIVITY IN HEMODIALYSIS PATIENTS

2020 ◽  
Vol 35 (Supplement_3) ◽  
Author(s):  
Joachim Beige ◽  
Ralph Wendt ◽  
Despina Rüssmann ◽  
Karl-Peter Ringel
Keyword(s):  
False Negative ◽  
False Negative Rate ◽  
Lymphocyte Transformation ◽  
Clinical Problem ◽  
Lymphocyte Transformation Test ◽  
Laboratory Research ◽  
Humoral Immune ◽  
Before And After ◽  
Positive Results

Abstract Background and Aims Incompatibility of dialysis procedure due to hypersensitivity against dialyzer material which currently is mainly based on polysulfone and derivatives can not be assessed by routine laboratory tests. Although the frequency of such symptoms is suspected to be low (below 2%) such resembles an important clinical problem because dialysis procedures are frequently accompanied by symptoms of non-tolerability with reasons not being entirely clear while circulatory reasons are suspected to play a major role. Method To enlighten the role of polysulfone hypersensitivity, we adapted known standardized material immune-toxicological tests (lymphocyte transformation test, basophil degranulation test) to the specific conditions of dialysis and polysulfone material sensitivity. We developed a method of polysulfone micronisation and measured humoral immune response of isolated patient´s lymphocytes when incubated with polysulfone dispersion. Results 39 samples from 103 patients with suspected polysulfone hypersensitivity showed positive results for type 1 (n=19), type 4 (n=18) or both type (n=2) reactions. There were no significant differences in the level of stimulation measured for DI, SI and lymphogenesis before and after dialysis (average delta -0.4; -0.28; - 1.74, p = 0.71; 0.34; 0.37) and with different dialyzer materials (Tab. 1). Patients with pos. type 4 results (LTT and lymphogenesis) showed highly correlated results in either LTT or lymphogenesis test (Fig. 1, R=0.87, p<0.0001). 8 out of 8 samples from patients with repeated test on different PS showed positive results on either PS. One patient tested positive on PS showed no hypersensitivity with another non-PS (PMMA) material. Conclusion This is the first methodological report showing plausible in-vitro results of patients samples concerning polysulfone intolerance. On the first superficial view, a “false-negative” rate of 60% looks rather disappointing, because all samples derived from patients with suspicion of PS hypersensitivity. However, due to the clinical variability of intolerance symptoms and the high prevalence of any problems after HD initiation, mainly of circulatory origin after initiating extracorporeal circuit, this rate may obviously express the true frequency of isolated PS material hypersensitivity in suspected patients. Alternative pathophysiological pathways of material sensitivity like complement activation, remain to be elucidated and incorporated into a comprehensive future testing panel. Further clinical and laboratory research is needed to define true polysulfone hypersensitivity and to enlighten the field of hypothetic subclinical material incompatibility in patients with impaired dialysis tolerability.

scholarly journals Macrolide-Resistant and Macrolide-Sensitive Mycoplasma pneumoniae Pneumonia in Children Treated Using Early Corticosteroids

2021 ◽  
Vol 10 (6) ◽  
pp. 1309
Author(s):  
Hye Young Han ◽  
Ki Cheol Park ◽  
Eun-Ae Yang ◽  
Kyung-Yil Lee
Keyword(s):  
Mycoplasma Pneumoniae ◽  
Serological Test ◽  
Corticosteroid Treatment ◽  
23S Rrna ◽  
Laboratory Parameters ◽  
The Mean ◽  
Domain V ◽  
Positive Results ◽  
Mycoplasma Pneumoniae Pneumonia

We have found that early corticosteroid therapy was effective for reducing morbidity during five Korea-wide epidemics. We evaluated the clinical and laboratory parameters of 56 children who received early corticosteroid treatment for pneumonia that was caused by macrolide-resistant Mycoplasma pneumoniae (M. pneumoniae) or macrolide-sensitive M. pneumoniae between July 2019 and February 2020. All subjects had dual positive results from a PCR assay and serological test, and received corticosteroids within 24–36 h after admission. Point mutation of residues 2063, 2064, and 2067 was identified in domain V of 23S rRNA. The mean age was 6.8 years and the male:female ratio was 1.2:1 (31:25 patients). Most of the subjects had macrolide-resistant M. pneumoniae (73%), and all mutated strains had the A2063G transition. No significant differences in clinical and laboratory parameters were observed between macrolide-resistant and macrolide-sensitive M. pneumoniae groups that were treated with early dose-adjusted corticosteroids. Higher-dose steroid treatment may be needed for patients who have fever that persists for >48 h or increased biomarkers such as lactate dehydrogenase concentration at follow-up despite a usual dose of steroid therapy.

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