Medical/biological Study (experimental study)

Determination of death thresholds and identification of Terahertz (THz)-specific gene expression signatures. med./biol.

Aim of study (according to author)
To study if high-power THz radiation causes cellular and/or molecular effects in human Jurkat cells and dermal fibroblast cell lines.

Endpoints

• molecular biosynthesis: gene expression
• cell viability/cell division/proliferation: cell viability

Exposure
General category: terahertz fields

Field characteristics	Parameters
field 1: 2.52 THz exposure duration: continuous for up to 15 s cell viability experiments with fibroblasts	power flux density: 227 mW/cm²
field 2: 2.52 THz exposure duration: continuous for 1 min or 2 min gene expression experiments	power flux density: 227 mW/cm²
field 3: 2.52 THz exposure duration: continuous for 5, 10, 20, 30, 40 min cell viability experiments with Jurkat cells	power flux density: 227 mW/cm²

Exposed system:
intact cell/cell culture (in vitro)
Jurkat cells (human lymphoblastoid T cells) and human dermal fibroblasts

Methods
Endpoint/Measurement parameters/Methodology

• molecular biosynthesis: gene expression (in fibroblasts; mRNA microarray)
• cell viability/cell division/proliferation: cell viability in (adherent) fibroblasts (propidium iodide and FITC-annexin V staining; confocal microscopy); cell viability in Jurkat cells (MTT assay); necrotic and apoptotic cell death in Jurkat cells (propidium iodide and FITC-annexin V staining; flow cytometry)

Main outcome of study (according to author)
The MTT assay showed that 60% of the Jurkat cells survived the 30-minutes THz exposure, whereas only 20% survived the 40-minutes exposure. The flow cytometry data showed similar results and provided additional evidence suggesting that THz-induced cell death was mediated by both necrotic and apoptotic processes.
The preliminary confocal microscopy data suggested that cells exposed to THz radiation for 12 seconds or longer show appreciable signs of cell death.
The preliminary microarray data showed that dermal fibroblasts upregulated several genes when exposed to THz irradiation (primarily inflammatory cytokines).
Overall, these findings provide evidence for the cellular and molecular effects of THz irradiation.

(Study character: medical/biological study, experimental study, full/main study, pilot/exploratory/preliminary study)

Study funded by

• Air Force Research Laboratory's (AFRL) Human Effectiveness Directorate, USA
• HQ AF/SGRS (Headquarters United States Air Force/Surgeon General Research and Development Divison), USA

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