Cytokinin replaces light in several aspects of the photomorphogenesis of dicot seedlings. Arabidopsis thaliana seedlings grown under red light have been shown to become disoriented, losing the negative hypocotyl gravitropism that has been observed in seedlings grown in darkness or white light. We report here that cytokinin at micromolar concentrations restores gravitropism to seedlings grown under red light. Cytokinin cancels the effect of red light on the gravity-sensing system and at the same time replaces light in the inhibition of hypocotyl elongation. Furthermore, application of the ethylene precursor 1 -aminocyclopropane-I -carboxylic acid acts similarly to cytokinin. Cytokinin cannot restore gravitropism under red light to an ethylene-insensitive mutant that is defective at the NN2 locus. Stimulation of ethylene production, therefore, can explain the action of cytokinin in restoring negative gravitropism to the hypocotyls of Arabidopsis seedlings grown under continuous red light.
Treating cancer is one of the major challenges of modern medicine. Since mice models are an important tool in cancer treatment research, it is required to assess murine tumor development. Existing methods for investigating tumor development are either high cost and limited by their availability or suffer from low accuracy and reproducibility. In order to overcome these drawbacks, thermography may be used. DA3 breast cancer carcinoma tumors in 12 Balb/c mice were thermally imaged and monitored for a period of several weeks. Eight mice were treated with diffusing alpha emitters radiation therapy (DaRT) wires, while four were treated with inert wires. For large tumors, the area was estimated by analyzing thermal images and was found to be in correlation with manual caliper measurements. In addition, the correlation between tumor area and relative temperatures was calculated and compared to previous works. Temperature differences were larger for tumors treated with DaRT wires than tumors with inert wires. These correlations can be used to assist in tumor size estimation and reveal information regarding its metabolic state. Overall, thermography was shown to be a promising tool for assessing tumor development with the additional advantages of being nonradiative and potentially providing indication of intratumoral biological processes.
Continuous monitoring of tumor temperature difference produces valuable information on tumor state and aggressiveness that can be used both in the clinic and in the laboratory. Monitoring can be either performed on a single image, or continuous on multiple images, revealing changes in tumor state.
Thermal differences between transplanted tumors and tumors in humans prevent the implementation of thermographic methods developed in mice models to human models and vise-versa. Transplantable tumors tend to have an extruding shape, which may affect the thermal patterns. This hypothesis was studied in phantom experiments and simulations. A correlation between tumor dimensions and relative temperature was found and used to estimate tumor functional state from previously published in vivo experiments. A correlation was found between temperature differences and tumor growth rates (tumor aggressiveness) and the effect of tumor treatment was demonstrated, showing the potential for in vivo, non-invasive tumor monitoring.
This study's objective is to validate a method for the measurement of two compound phantoms as a proof of concept for oxygen saturation level measurement via a thermal imaging bundle. The method consists of a thermal imaging system and an algorithm which estimates the compound concentration according to temperature rise. A temperature rise is obtained by illuminating the tissue with a laser with different wavelengths in the NIR range and measured using a thermal camera. A coherent thermal imaging bundle was used for image transmittance for minimal invasive transendoscopic use. The algorithm's estimation ability was evaluated using agar phantoms of varying Methylene Blue and ICG ratios as well as blood samples The Methylene Blue ratio in each phantom was estimated and the calculated average RMS of the error was 9.38%, a satisfying value for this stage, verifying the algorithm's and bundle's suitability for the use in a minimal invasive system.
The objective of this study is to develop a minimal invasive thermal imaging method to determine the oxygenation level of an internal tissue. In this method, the tissue is illuminated using an optical fiber by several wavelengths in the visible and near-IR range. Each wavelength is absorbed by the tissue and thus causes increase in its temperature. The temperature increase is observed by a coherent waveguide bundle in the mid-IR range. The thermal imaging of the tissue is done using a thermal camera through the coherent bundle. Analyzing the temperature rise allows estimating the tissue composition in general, and specifically the oxygenation level. Such a system enables imaging of the temperature within body cavities through a commercial endoscope. As an intermediate stage, the method is applied and tested on exposed skin tissue. A curve-fitting algorithm is used to find the most suitable saturation value affecting the temperature function. The algorithm is tested on a theoretical tissue model with various parameters, implemented for this study, and on agar phantom models. The calculated saturation values are in agreement with the real saturation values.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.