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Biomedical subjects

Stephan Gabos

Publications and source records attributed to Stephan Gabos.

8 recordsLinked to original sources
PubMed2006

Microelectronic cell sensor assay for detection of cytotoxicity and prediction of acute toxicity.

This study reports in-house assessment of a real-time cell electronic sensing (RT-CES) system used as a test platform for both cytotoxicity assay and predicting acute toxicity. For cytotoxicity determination, the RT-CES assay displayed equal sensitivity and coefficients of variation values with good correlation to NRU assay. The IC50 values and the LD50 values for the cytotoxicity reference materials were compared in the context of the proposed prediction model for acute rodent toxicity. The results obtained from RT-CES assay fitted within the acceptance limits of the prediction model and showed that the RT-CES cytotoxicity assay met the qualification guidelines in NIH Publication #01-4500 to accurately predict acute toxicity. In addition to cell viability, the RT-CES assay provided dynamic information that can be used to identify maximum toxicity and reversibility of the toxic effects which are difficult to achieve by the endpoint assays and, therefore, the RT-CES assay is more accurate for assessment of cytotoxicity. The features of the RT-CES assay, such as labeling free, automatic detection, and easy operation, give this assay potential to replace BALB/c 3T3 NRU assay and be used as routine setting for drug monitoring in the toxicological laboratory.

Animals↗
PubMed2006

Chromium on the hands of children after playing in playgrounds built from chromated copper arsenate (CCA)-treated wood.

Children's exposure to arsenic and chromium from playground equipment constructed with chromated copper arsenate (CCA)-treated wood is a potential concern because of children's hand-to-mouth activity. However, there exists no direct measure of Cr levels on the hands of children after playing in such playgrounds. In this study we measured both soluble and total Cr on the hands of 139 children playing in playgrounds, eight of which were constructed with CCA-treated wood and eight of which were not. Children's age and duration of play were recorded. The hands of each child were washed after play with 150 mL deionized water, which was collected in a bag and subsequently underwent analysis of Cr and 20 other elements, using inductively coupled plasma mass spectrometry. Total average Cr on the hands of 63 children who played in CCA playgrounds was 1,112 +/- 1,089 ng (median, 688; range 78-5,875). Total average Cr on the hands of 64 children who played in non-CCA playgrounds was 652 +/- 586 ng (median, 492; range 61-3,377). The difference between the two groups is statistically significant (p < 0.01). Cr levels were highly correlated to both Cu (r = 0.672) and As (r = 0.736) levels in CCA playgrounds (p < or = 0.01), but not non-CCA playgrounds (r = 0.252 and 0.486 for Cu and As, respectively). Principal-component analysis indicates that Cr, Cu, and As are more closely grouped together in CCA than in non-CCA playgrounds. These results suggest that the elevated levels of Cr and As on children's hands are due to direct contact with CCA wood.

Arsenates↗
PubMed2005

Dynamic monitoring of cytotoxicity on microelectronic sensors.

A real-time cell electronic sensing (RT-CES) system was used for label-free, dynamic measurement of cell responses to cytotoxicants. Cells were grown onto the surfaces of microelectronic sensors, which are comprised of circle-on-line electrode arrays and are integrated into the bottom surfaces of the microtiter plate. Changes in cell status such as cell number, viability, morphology, and adherence were monitored and quantified by detecting sensor electrical impedance. For cell quantification and viability measurement, the data generated on the RT-CES system correlated well with those from the colorimetric (MTT) assay. For cytotoxicity assessment, cells growing on microelectronic sensors were treated with different cytotoxicants, such as arsenic, mercury, and sodium dichromate. The dynamic responses of the cells to the toxicants were continuously monitored by the RT-CES system. On the basis of the IC50 values, the RT-CES system displays an equal sensitivity to the neutral red uptake assay at specific time points. Furthermore, because the RT-CES system provides real-time information regarding the state of cell morphology and adhesion in addition to cell number, we were able to discern a previously unreported effect of arsenic on NIH 3T3 cells prior to cell death. Also, using the RT-CES system, we were able to monitor cytotoxicity effects that occur within a minute of compound addition. Taken together, the RT-CES system allows for real-time, continuous monitoring and quantitative recording of the whole assay process and provides new insight into the cell-toxicant interaction.

Animals↗
PubMed2005

Development of a microelectronic chip array for high-throughput genotyping of Helicobacter species and screening for antimicrobial resistance.

A microelectronic array assay was developed to specifically genotype Helicobacter pylori versus Helicobacter heilmannii and to determine antimicrobial resistance. Helicobacter 16S rRNA and 23S rRNA genes were specifically generated with Helicobacter genus-specific primers, respectively. The single-nucleotide polymorphisms (SNPs) in 16S rRNA, 268T specific in the H. pylori sequence, and 263A specific in H. heilmannii were used as molecular markers for identification of H. pylori and H. heilmannii, respectively. A triple-base-pair resistant mutation, AGA965-967TTC in 16S rRNA, is known to be responsible for H. pylori tetracycline resistance and was detected to identify resistant strains. H. pylori macrolide resistance was determined by the identification of 3 defined mutations in the 23S rRNA gene using the same method. The assay could be directly used to detect H. pylori in feces. The assay performs multiple determinations, including identification of Helicobacter species and antibiotic resistances, on the same microelectronic platform and is highly amenable to the development of other DNA-based assays.

Base Sequence↗
PubMed2004

Arsenic on the hands of children after playing in playgrounds.

Increasing concerns over the use of wood treated with chromated copper arsenate (CCA) in playground structures arise from potential exposure to arsenic of children playing in these playgrounds. Limited data from previous studies analyzing arsenic levels in sand samples collected from CCA playgrounds are inconsistent and cannot be directly translated to the amount of children's exposure to arsenic. The objective of this study was to determine the quantitative amounts of arsenic on the hands of children in contact with CCA-treated wood structures or sand in playgrounds. We compared arsenic levels on the hands of 66 children playing in eight CCA playgrounds with levels of arsenic found on the hands of 64 children playing in another eight playgrounds not constructed with CCA-treated wood. The children's age and duration of playtime were recorded at each playground. After play, children's hands were washed in a bag containing 150 mL of deionized water. Arsenic levels in the hand-washing water were quantified by inductively coupled plasma mass spectrometry. Our results show that the ages of the children sampled and the duration of play in the playgrounds were similar between the groups of CCA and non-CCA playgrounds. The mean amount of water-soluble arsenic on children's hands from CCA playgrounds was 0.50 microg (range, 0.0078-3.5 microg). This was significantly higher (p < 0.001) than the mean amount of water-soluble arsenic on children's hands from non-CCA playgrounds, which was 0.095 microg (range, 0.011-0.41 microg). There was no significant difference in the amount of sand on the children's hands and the concentration of arsenic in the sand between the CCA and non-CCA groups. The higher values of arsenic on the hands of children playing in the CCA playgrounds are probably due to direct contact with CCA-treated wood. Washing hands after play would reduce the levels of potential exposure because most of the arsenic on children's hands was washed off with water. The maximum amount of arsenic on children's hands from the entire group of study participants was < 4 microg, which is lower than the average daily intake of arsenic from water and food.

Arsenates↗
PubMedDate not supplied

Potential factors that may affect acceptance of routine prenatal HIV testing.

BACKGROUND: Despite increasing advocacy for an "opt-out" strategy in routine prenatal HIV screening programs in Canada, no published studies have examined factors that may affect acceptance of prenatal HIV testing. METHODS: We included all pregnant women in Alberta who received prenatal care (N = 38,712) and their caregivers (N = 2,007) between January 1 and November 30, 2000. Factors associated with non-acceptance of HIV testing in both pregnant women and their caregivers were assessed using multivariate logistic regression. RESULTS: Overall, 1.5% of women declined HIV testing. First Nations women were about twice as likely to decline the test (adjusted odds ratio [OR(adj)] 1.91, 95% CI [1.42-2.58]) compared to non-First Nations women (p < 0.001). The proportion also increased with age (chi2 trend p < 0.001) in the general population. In First Nations women, however, most (3.2%) declined in the 20-24 year age group. No significant effect was seen for a socio-economic status marker or for the place of residence. The caregivers of women who declined HIV testing were more likely to be female (OR(adj) 1.56 [1.28-1.89]), midwives (OR(adj) 140.65 [58.61-337.49]), other non-obstetrical medical specialties (OR(adj) 4.92 [1.94-12.47]), and general practitioners (OR(adj) 3.44 [1.87-6.33]). CONCLUSION: In an "opt-out" routine prenatal HIV screening program, the characteristics of both the pregnant women and their caregivers may contribute to the non-acceptance of HIV testing. A higher likelihood of declining HIV testing among First Nations pregnant women and other pregnant women under the care of midwives and female physicians warrants further study.

AIDS Serodiagnosis↗