Currently, intracranial pressure (ICP) is the primary clinical monitoring parameter for traumatic brain injury (TBI). However, during the hyperacute phase of TBI, ICP value lags behind changes of brain temperature (BT) and neurometabolic activity. This is due to the compensatory capacity of the intracranial space. Here, we explored BT changes and concentration changes of cytochrome c (∆Ccytc) during the hyper-acute phase of TBI. Nine mice were randomly divided into control group, mild TBI group, and severe TBI group. The mouse TBI model is created by using various levels of striking force. The strike device is designed and improved based on Feeney's free fall model. BT can be measured by a minimally invasive measurement probe, allowing for the observation of changes in both time and spatial distribution. ∆Ccytc was calculated using an intrinsic optical signal imaging system (IOSI). The relationship between BT and ∆Ccytc was analyzed during the development of mice TBI models.
Photodynamic therapy (PDT) involves three interdependent parameters, including photosensitizer (PS), light, and oxygen (O2). Obtaining an appropriate PDT dosimetry remains a highly challenging and labor-intensive work. In this paper, we described the design and assembly of a low-cost dual-wavelength illumination system for the in vitro PDT experimentation. A light-emitting diode (LED) array was designed to irradiate cells at 625 nm and 408 nm, respectively. An optical filtering layer with a printed pattern of five gradient pixel grey values was inserted between the LED panel and 96-well plate to achieve spatial light intensity control. The device was further integrated with an air-permeable aerogel monolith apparatus allowing for gas diffusion and delivery. The system performance was confirmed by testing the efficacy of 5-aminolevulinic acid (5-ALA)-assisted PDT on human breast cancer cell MCF-7. Cell viability results suggested that the high-energy violet light irradiation at 408 nm resulted in a more pronounced 5-ALA phototoxic effect at a much lower light dose. The gradient increase of the light dose for either red or violet light was followed by decreased cell viability. Regardless of irradiation conditions, the hypoxic environment significantly reduced the efficacy of 5-ALA-PDT. In conclusion, the illumination system can be used for reproducible and convenient in vitro PDT testing on the presentation of appropriate dosimetry of different light doses and wavelengths.
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