Non-invasive determination of plant biomass with microwave resonators

Non-invasive and rapid determination of plant biomass would be beneficial for a number of research aims. Here, we present a novel device to non-invasively determine plant water content as a proxy for plant biomass. It is based on changes of dielectric properties inside a microwave cavity resonator induced by inserted plant material. The water content of inserted shoots leads to a discrete shift in the centre frequency of the resonator. Calibration measurements with pure water showed good spatial homogeneity in the detection volume of the microwave resonators and clear correlations between water content and centre frequency shift. For cut tomato and tobacco shoots, linear correlations between fresh weight and centre frequency shift were established. These correlations were used to continuously monitor diel growth patterns of intact plants and to determine biomass increase over several days. Interferences from soil and root water were excluded by shielding pots with copper. The presented proof of principle shows that microwave resonators are promising tools to quantitatively detect the water content of plants and to determine plant biomass. As the method is non-invasive, integrative and fast, it provides the opportunity for detailed, dynamic analyses of plant growth, water status and phenotype.     

Non-invasive marker-independent high content analysis of a microphysiological human pancreas-on-a-chip model

The increasing prevalence of diabetes, its heterogeneity, and the limited number of treatment options drive the need for physiologically relevant assay platforms with human genetic background that have the potential to improve mechanistic understanding and expedite diabetes-related research and treatment. In this study, we developed an endocrine pancreas-on-a-chip model based on a tailored microfluidic platform, which enables self-guided trapping of single human pseudo-islets. Continuous, low-shear perfusion provides a physiologically relevant microenvironment especially important for modeling and monitoring of the endocrine function as well as sufficient supply with nutrients and oxygen. Human pseudo-islets, generated from the conditionally immortalized EndoC-βH3 cell line, were successfully injected by hydrostatic pressure-driven flow without altered viability. To track insulin secretion kinetics in response to glucose stimulation in a time-resolved manner, dynamic sampling of the supernatant as well as non-invasive real-time monitoring using Raman microspectroscopy was established on-chip. Dynamic sampling indicated a biphasic glucose-stimulated insulin response. Raman microspectroscopy allowed to trace glucose responsiveness in situ and to visualize different molecular structures such as lipids, mitochondria and nuclei. In-depth spectral analyses demonstrated a glucose stimulation-dependent, increased mitochondrial activity, and a switch in lipid composition of insulin secreting vesicles, supporting the high performance of our pancreas-on-a-chip model.     

Non-invasive determination of bacterial single cell properties by electrorotation

So far, electrorotation and its application to the determination of single cell properties have been limited to eukaryotes. Here an experimental system is described that allows the recording of electrorotation spectra of single bacterial cells. The small physical dimensions of the developed measuring chamber combined with a single frame video analysis made it possible to monitor the rotation of objects as small as bacteria by microscopical observation despite Brownian rotation and cellular movement. Thus physical properties of distinct organelles of E. coli could be simultaneously determined in vivo at frequencies between 1 kHz and 1 GHz. Experimental data were evaluated following a three-shell model of the cell. Electrical conductivities of cytoplasm and outer membrane were determined to 4.4 mS/cm and 25 microS/cm, respectively, that of the periplasmic space was found to increase with the square root of the medium ionic strength. Specific capacitances of inner and outer membrane amounted to 1.4 microF/cm2 and 0.26 microF/cm2, respectively, the thickness of the periplasm to about 50 nm. Heat treatment of the cells lead to a reduction of cytoplasmic conductivity to 0.9 mS/cm, probably caused by an efflux of ions through the permeabilized inner membrane.     

Non-invasive measurement of brain damage in a primate model of multiple sclerosis

Early recognition of whether a product has potential as a new therapy for treating multiple sclerosis (MS) relies upon the quality of the animal models used in the preclinical trials. The promising effects of new treatments in rodent models of experimental autoimmune encephalomyelitis (EAE) have rarely been reproduced in patients suffering from MS. EAE in outbred marmoset monkeys, Callithrix jacchus, is a valid new model, and might provide an experimental link between EAE in rodent models and human MS. Using magnetic resonance imaging techniques similar to those used in patients suffering from MS pathological abnormalities in the brain, white matter of the animal can be visualized and quantified. Moreover, NMR spectroscopy, in combination with pattern recognition, offers an advanced uroscopic technique for the identification of biomarkers of inflammatory demyelination.     

Non-invasive determination of plant-associated bacteria in the phyllosphere of plants

Epiphytic living Pseudomonas strains isolated from different Malus domestica cultivars were transformed with two reporter genes [green fluorescent protein (gfp) and luciferase (luxAB)]. The establishment and distribution of these bacteria on sterile, in vitro-propagated, and thus genetically identical, Malus domestica plants were continuously analysed with a cooled, back-illuminated, charge-coupled-device (CCD) camera system. The combination of the assessment of bioluminescence and the use of a CCD camera offer an intriguing method to study, non-invasively and in real time, plant-microbe interactions as well as the colonization of the phyllosphere by microorganisms. Here we report on the applicability and sensitivity of the method with the goal to investigate quantitatively the interaction of symbiotic and pathogenic microorganisms with the corresponding host plant. It will be shown that the three bacterial isolates of the genus Pseudomonas studied, differ considerably with respect to their establishment on the host plants. It will also be shown that the chosen host apple variety has an impact on the activity of the bacterial cultivars. Analysis by a laser scanning fluorescence microscope provides the first evidence for the mode by which the epiphytic microorganisms interact with the plant.     

Non-invasive prediction of skin flap shrinkage: a new concept based on animal experimental evidence

A non-invasive, in vivo method has been developed to predict the skin flap shrinkage (retraction) following a harvest. It involves the use of a novel custom-designed extensometer to measure the force-displacement behaviour of skin and subsequent data analysis to estimate the shrinkage. In validation experiments performed on pigs, this method has been shown to produce results with an average absolute error of 6.0% between the actual and predicted shrinkages. This may be close to what an experienced surgeon would estimate subjectively, thus indicating the potential usefulness of this method to predict flap shrinkage of patient's donor sites.     

Validation of a rodent model of source memory

Source memory represents the origin (source) of information. Recently, we proposed that rats (Rattus norvegicus) remember the source of information. However, an alternative to source memory is the possibility that rats selectively encoded some, but not all, information rather than retrieving an episodic memory. We directly tested this ‘encoding failure’ hypothesis. Here, we show that rats remember the source of information, under conditions that cannot be attributed to encoding failure. Moreover, source memory lasted at least seven days but was no longer present 14 days after studying. Our findings suggest that long-lasting source memory may be modelled in non-humans. Our model should facilitate attempts to elucidate the biological underpinnings of source memory impairments in human memory disorders such as Alzheimer''s disease.     

Non-invasive methods for determination of cellular growth inPodophyllum hexandrum suspension cultures

Culture conductivity and on-line NADH fluorescence were used to measure cellular growth in plant cell suspension cultures ofPodophyllum hexandrum. An inverse correlation between dry cell weight and medium conductivity was observed during shake flask cultivation. A linear relationship between dry cell weight and culture NADH fluorescence was obtained during the exponential phase of batch cultivation in a bioreactor under the pH stat (pH 6) conditions. It was observed that conductivity measurement were suitable for biomass characterisation under highly dynamic uncontrolled shake flask cultivation conditions. However, if the acid/alkali feeding is done for pH control the conductivity measurement could not be applied. On the other hand the NADH fluorescence measurement allowed online-in situ biomass monitoring of rather heterogenous plant cell suspension cultures in bioreactor even under the most desirable pH stat conditions.     

小鼠哮喘模型通气功能检测实验器材的改进

通气功能检测可直接反映支气管痉挛等所造成的气道阻力等的改变 ,是判定支气管哮喘动物模型的可靠指标 ,目前国外小鼠支气管哮喘模型多采用此项检测 ,但国内尚未见报道。它的部分实验器材在国内很难仿制 ,哈佛动物呼吸器造价昂贵 ,我们对其器材进行改进 ,并作以简要报道。Ｆｉｇ.1ＥｘｐｅｒｉｍｅｎｔａｌａｐｐｌｉａｎｃｅｓＡ :ｂｅｆｏｒｅｉｍｐｒｏｖｉｎｇ ;Ｂ :ａｆｔｅｒｉｍｐｒｏｖｉｎｇＦｉｇ .2Ｄｉａｇｒａｍｍａｔｉｃｒｅｐｒｅｓｅｎｔａｔｉｏｎｏｆｒｏｄｅｎｔｖｅｎｔｉｌａｔｏｒ1　材料与方法(1)实验器材　①实验…     

Principles and applications of dual source CT

This article describes the technical principles and clinical applications of dual source CT. A dual source CT (DSCT) is a CT system with two x-ray tubes and two detectors at an angle of approximately 90°. Both measurement systems acquire CT scan data simultaneously at the same anatomical level of the patient (same z-position). DSCT provides temporal resolution of approximately a quarter of the gantry rotation time for cardiac, cardio-thoracic and pediatric imaging. Successful imaging of the heart and the coronary arteries at high and variable heart rates has been demonstrated. DSCT systems can be operated at twice the spiral pitch of single source CT systems (up to pitch 3.2). The resulting high table speed is beneficial for pediatric applications and fast CT angiographic scans, e. g. of the aorta or the extremities. Operating both X-ray tubes at different tube potential (kV) enables the acquisition of dual energy data and the corresponding applications such as monoenergetic imaging and computation of material maps. Spectral separation can be improved by different filtration of the X-ray beams of both X-ray tubes. As a downside, DSCT systems have to cope with some challenges, among them the limited size of the second measurement system, and cross-scattered radiation.     

Non-invasive determination of coupled motion of the scapula and humerus--an in-vitro validation

Measuring the motion of the scapula and humerus with sub-millimeter levels of accuracy in six-degrees-of-freedom (6-DOF) is a challenging problem. The current methods to measure shoulder joint motion via the skin do not produce clinically significant levels of accuracy. Thus, the purpose of this study was to validate a non-invasive markerless dual fluoroscopic imaging system (DFIS) model-based tracking technique for measuring dynamic in-vivo shoulder kinematics. Our DFIS tracks the positions of bones based on their projected silhouettes to contours on recorded pairs of fluoroscopic images. For this study, we compared markerlessly tracking the bones of the scapula and humerus to track them with implanted titanium spheres using a radiostereometric analysis (RSA) while manually manipulating a cadaver specimen's arms. Additionally, we report the repeatability of the DFIS to track the scapula and humerus during dynamic shoulder motion. The difference between the markerless model-based tracking technique and the RSA was ±0.3 mm in translation and ±0.5° in rotation. Furthermore, the repeatability of the markerless DFIS model-based tracking technique for the scapula and humerus was ±0.2 mm and ±0.4°, respectively. The model-based tracking technique achieves an accuracy that is similar to an invasive RSA tracking technique and is highly suited for non-invasively studying the in-vivo motion of the shoulder. This technique could be used to investigate the scapular and humeral biomechanics in both healthy individuals and in patients with various pathologies under a variety of dynamic shoulder motions encountered during the activities of daily living.     

Non-invasive algorithm for bowel motility estimation using a back-propagation neural network model of bowel sounds

Background

Although cardiac auscultation remains important to detect abnormal sounds and murmurs indicative of cardiac pathology, the application of electronic methods remains seldom used in everyday clinical practice. In this report we provide preliminary data showing how the phonocardiogram can be analyzed using color spectrographic techniques and discuss how such information may be of future value for noninvasive cardiac monitoring.

Methods

We digitally recorded the phonocardiogram using a high-speed USB interface and the program Gold Wave http://www.goldwave.com in 55 infants and adults with cardiac structural disease as well as from normal individuals and individuals with innocent murmurs. Color spectrographic analysis of the signal was performed using Spectrogram (Version 16) as a well as custom MATLAB code.

Results

Our preliminary data is presented as a series of seven cases.

Conclusions

We expect the application of spectrographic techniques to phonocardiography to grow substantially as ongoing research demonstrates its utility in various clinical settings. Our evaluation of a simple, low-cost phonocardiographic recording and analysis system to assist in determining the characteristic features of heart murmurs shows promise in helping distinguish innocent systolic murmurs from pathological murmurs in children and is expected to useful in other clinical settings as well.     

Implementation of a Hebbian chemoreceptor model for diffusive source localization

While new approaches to chemical localization have been proposed, animals are still widely used for locating landmines and illegal substances. Existing electronic noses still do not have the necessary sensitivity and accuracy. By modeling a cell’s chemical detection system, we can gain insight into the basic “olfactory” system. We use an inspiration from chemotaxis and Hebbian learning to enhance localization and tracking of gradient sources, which can be applied to both chemicals and heat. The eukaryotic receptor clustering model shows improvement over previous prokaryotic chemotaxis-inspired methods that do not take into account receptor clustering. Receptor clustering essentially adapts receptors spatio-temporally. For a mobile simulation, our method locates the source in less convergence time than the other chemotaxis algorithms and insignificantly less time compared to no spatio-temporal filtering (e.g. a single-sensor memoryless case). We then show that local regions of receptor cooperation have the best performance reflecting observations of receptor behavior in biology. To demonstrate the performance of this system in real-time, a stationary 4/8-sensor version of the array is implemented, and the algorithm improves the convergence time, mean, and variance of the Direction-of-Arrival calculation in diffusive, turbulent, and noisy environments.     

A generalized mathematical model for the growth kinetics of Saccharomyces cerevisiae with experimental determination of parameters

A general model of the kinetics of microbial growth has been developed involving the kinetics of incorporation of substrate into biomass and the maintenance energy requirements. Results obtained from batch cultures of the yeast Saccharomyces cerevisiae growing in synthetic media at pH 5.1 and 30°C permitted all biological parameters in the model to be calculated. Values obtained for these parameters were: maximum specific glucose uptake rate (μS_m), 2.08 g/g biomass/hr; apparent Michaelis constant for glucose (K_S), 0.1 g/liter (5.5 × 10^?4M) apparent Michaelis constant for oxygen (K_L), 1.4% O₂ (3.2 × 10^?6 M) quantitative index of the Pasteur effect (b), 4.9 × 10^?4%^?1 O₂ (207 M ^?1). Under conditions of strongly substrate-repressed respiration the values obtained for Y_ATP and P/O were constant over the course of the exponential phase of growth (Y_ATP = 10.4 g biomass/mole ATP; P/O = 3 moles ATP/atom 0). Mass balances for aerobic and anaerobic cultures confirmed the results obtained form the generalized model. Results presented suggested the operation of a mechanism for regulating energy-yielding metabolism which involved an equilibrium between the systems of oxidative phosphorylation and dephosphorylation and was dependent upon the level of catbolite repression.     

CT imaging with iopromide liposomes in a rabbit model

The aim of this study was to evaluate the computed tomography (CT)-imaging potential of iopromide-carrying liposomes (SPC/CH/SPG, 6:3:1) of approximately 200?nm in diameter in healthy rabbits and in rabbits with implanted liver tumors in an intraindividual comparison with iopromide. Normal rabbits and animals with VX2 tumors implanted into the liver received iopromide (600?mg of iodine/kg, bolus injection) and, 1 or 2 days later, iopromide liposomes (300?mg of iodine/kg, bolus injection or 10-minute infusion). CT imaging up to 1 hour after administration was performed, focusing on the aorta, vena cava, kidney, spleen, and liver. Pharmacokinetic parameters for CT enhancement were calculated. Detectability and delineation of liver lesions were assessed on a 4-grade scale, and differences were evaluated statistically. Using half the iodine dose, iopromide liposomes achieved similar blood-pool enhancement as iopromide. Detectability and delineation of liver lesions were easy/good in the arterial phase after iopromide injection, but poor in the venous and equilibration phases. Iopromide liposomes resulted in a long-lasting, good detectability and delineation of liver lesions similar or superior to that observed after iopromide in the arterial phase.