Planarian activity differences when maintained in water pre-treated with magnetic fields: a nonlinear effect

There have been multiple claims that exposing water to a static magnetic field affects its properties which influence living systems. To test this hypothesis, planarian subsequent to dissection were maintained in spring water that had been previously exposed for only one day to one of three (16, 160, or 1,600 G) intensity static magnetic fields or to a reference condition. Although there was no significant difference in regeneration rates over the subsequent seven-day period, there was a statistically significant nonlinear effect for planarian mobility and diffusion rates. Both mobility rates and diffusion velocity of a liquid within the water that had been exposed to the 16 G field was about twice that for water exposed to the other intensities. These results imply that nonlinear biophysical effects may emerge under specific conditions of intensity ranges for particular volumes of water.     

Spectral imaging for precise surgical intervention in Hirschsprung's Disease

We used advanced spectral imaging for intrasurgical decision making in a preclinical study, on a mouse model of Hirschsprung's Disease. Our imaging device sampled areas from normal and abnormal (aganglionic) colon in these animals. Spectral segmentation and classification of the resulting images showed a clear distinction between the normal and aganglionic regions, as confirmed by pathological analysis and use of mutant mice. We developed a simple algorithm that could distinguish normal from aganglionic colon with high spatial resolution and reproducibility, and the following statistics: sensitivity = 97%, specificity = 94%, positive predictive value = 92%, negative predictive value = 98%. These studies showed translational proof of concept that spectral imaging could be used during operations, in real time, to help surgeons precisely distinguish normal from abnormal tissue without requiring traditional biopsy. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

A novel aggregation-induced emission fluorescent probe for nucleic acid detection and its applications in cell imaging

A new kind of aggregation-induced emission compound was synthesized and used as the probe of nucleic acid. The characterization of this compound was studied. Both the RNA and DNA were detected by using this probe. And the detection scope of DNA and RNA was different. We researched the selectivity of our probe in double and single strand DNA sequences. The visualization of gel electrophoresis and the cell nucleus imaging were researched as well. Compared with the traditional nucleus dye Hoechst 33258, our probe also has the potential to be nucleus dye. And the cell toxicity was well performed by MTT assays.     

Bladder tissue characterization using probe‐based Raman spectroscopy: Evaluation of tissue heterogeneity and influence on the model prediction

Existing approaches for early‐stage bladder tumor diagnosis largely depend on invasive and time‐consuming procedures, resulting in hospitalization, bleeding, bladder perforation, infection and other health risks for the patient. The reduction of current risk factors, while maintaining or even improving the diagnostic precision, is an underlying factor in clinical instrumentation research. For example, for clinic surveillance of patients with a history of noninvasive bladder tumors real‐time tumor diagnosis can enable immediate laser‐based removal of tumors using flexible cystoscopes in the outpatient clinic. Therefore, novel diagnostic modalities are required that can provide real‐time in vivo tumor diagnosis. Raman spectroscopy provides biochemical information of tissue samples ex vivo and in vivo and without the need for complicated sample preparation and staining procedures. For the past decade there has been a rise in applications to diagnose and characterize early cancer in different organs, such as in head and neck, colon and stomach, but also different pathologies, for example, inflammation and atherosclerotic plaques. Bladder pathology has also been studied but only with little attention to aspects that can influence the diagnosis, such as tissue heterogeneity, data preprocessing and model development. The present study presents a clinical investigative study on bladder biopsies to characterize the tumor grading ex vivo, using a compact fiber probe‐based imaging Raman system, as a crucial step towards in vivo Raman endoscopy. Furthermore, this study presents an evaluation of the tissue heterogeneity of highly fluorescent bladder tissues, and the multivariate statistical analysis for discrimination between nontumor tissue, and low‐ and high‐grade tumor.     

Effects of leaf shape plasticity on leaf surface temperature

干旱区植物叶片形态可塑性是植物适应高温干旱环境的重要生存策略, 但目前仍缺乏直观的数据予以证明。该研究应用热成像技术和图像分析技术, 同步测定真实叶片与模拟叶片的叶温、形态及风速、辐射和温度等环境参数。研究结果显示: 在干旱、高温环境下, 除了蒸腾, 叶片形态变化也是调控叶温的重要因子。干旱区植物叶片变小, 有利于加速叶片与环境的物质及热量交换, 从而达到降低叶温的目的。样地数据显示, 在高温、低风速环境下, 叶片宽度每减少1 cm, 叶片表面温度降低约2.1 ℃, 而模拟叶片叶宽度每减少1 cm, 叶片表面温度降低0.60-0.86 ℃。该研究对深入理解植物生存策略与环境适能力具有重要意义。     

Prefrontal deep projection neurons enable cognitive flexibility via persistent feedback monitoring

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An X-ray spectrum estimation method from transmission measurement combined with scatter correction

PurposeConventional x-ray spectrum estimation methods from transmission measurement often lead to inaccurate results when extensive x-ray scatter is present in the measured projection. This study aims to apply the weighted L1-norm scatter correction algorithm in spectrum estimation for reducing residual differences between the estimated and true spectrum.MethodThe scatter correction algorithm is based on a simple radiographic scattering model where the intensity of scattered x-ray is directly estimated from a transmission measurement. Then, the scatter-corrected measurement is used for the spectrum estimation method that consists of deciding the weights of predefined spectra and representing the spectrum as a linear combination of the predefined spectra with the weights. The performances of the estimation method combined with scatter correction are evaluated on both simulated and experimental data.ResultsThe results show that the estimated spectra using the scatter-corrected projection nearly match the true spectra. The normalized-root-mean-square-error and the mean energy difference between the estimated spectra and corresponding true spectra are reduced from 5.8% and 1.33 keV without the scatter correction to 3.2% and 0.73 keV with the scatter correction for both simulation and experimental data, respectively.ConclusionsThe proposed method is more accurate for the acquisition of x-ray spectrum than the estimation method without scatter correction and the spectrum can be successfully estimated even the materials of the filters and their thicknesses are unknown. The proposed method has the potential to be used in several diagnostic x-ray imaging applications.     

Investigation of the magnetic susceptibility properties of fresh and fixed mouse heart,liver, skeletal muscle and brain tissue

PurposeSeveral magnetic resonance imaging (MRI) techniques exploit the difference in magnetic susceptibilities between tissues, but systematic measurements of tissue susceptibility are lacking. Furthermore, there is the question as to whether chemical fixation that is used for ex vivo MRI studies, affects the magnetic properties of the tissue. Here, we determined the magnetic susceptibility and water content of fresh and chemically fixed mouse tissue.MethodsMass susceptibility of brain, heart, liver and skeletal muscle samples were determined on a vibrating sample magnetometer at room temperature. Measurements at 50, 125, 200 and 295 K were performed to assess the temperature dependence of susceptibility. Moreover, we measured water content of fresh and fixed samples.ResultsAll samples show mass susceptibilities between −0.068 and −1.929 × 10⁻⁸ m³/kg, compared to −9.338 × 10⁻⁹ m³/kg of double distilled water. Heart tissue has a more diamagnetic susceptibility than the other tissues. Compared to fresh tissue, fixed tissue has a less diamagnetic susceptibility. Fixed tissue was not different in water content to fresh tissue and showed no consistent dependence of susceptibility with temperature, whereas fresh tissue shows a decrease to at least 125 K, indicative of a paramagnetic component.ConclusionsBiological tissues are diamagnetic in comparison to water, where the heart is more diamagnetic than the other tissues, with paramagnetic contributions. Fixation rendered tissue less diamagnetic compared to fresh tissue. Our measurements revealed differences in tissue susceptibility between VSM and QSM, inviting more research to compare susceptibility-based MRI methods with physical measurements of tissue susceptibility.     

An Ex vivo Culture System to Study Thyroid Development

The thyroid is a bilobated endocrine gland localized at the base of the neck, producing the thyroid hormones T3, T4, and calcitonin. T3 and T4 are produced by differentiated thyrocytes, organized in closed spheres called follicles, while calcitonin is synthesized by C-cells, interspersed in between the follicles and a dense network of blood capillaries. Although adult thyroid architecture and functions have been extensively described and studied, the formation of the “angio-follicular” units, the distribution of C-cells in the parenchyma and the paracrine communications between epithelial and endothelial cells is far from being understood.This method describes the sequential steps of mouse embryonic thyroid anlagen dissection and its culture on semiporous filters or on microscopy plastic slides. Within a period of four days, this culture system faithfully recapitulates in vivo thyroid development. Indeed, (i) bilobation of the organ occurs (for e12.5 explants), (ii) thyrocytes precursors organize into follicles and polarize, (iii) thyrocytes and C-cells differentiate, and (iv) endothelial cells present in the microdissected tissue proliferate, migrate into the thyroid lobes, and closely associate with the epithelial cells, as they do in vivo.Thyroid tissues can be obtained from wild type, knockout or fluorescent transgenic embryos. Moreover, explants culture can be manipulated by addition of inhibitors, blocking antibodies, growth factors, or even cells or conditioned medium. Ex vivo development can be analyzed in real-time, or at any time of the culture by immunostaining and RT-qPCR.In conclusion, thyroid explant culture combined with downstream whole-mount or on sections imaging and gene expression profiling provides a powerful system for manipulating and studying morphogenetic and differentiation events of thyroid organogenesis.