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The selective pressure imposed by extrinsic death signals and stressors adds to the challenge of isolating and interpreting the roles of proteins in stress-activated signaling networks. By expressing a kinase with activating mutations and a caged lysine blocking the active site, we can rapidly switch on catalytic activity with light and monitor the ensuing dynamics. Applying this approach to MAP kinase 6 (MKK6), which activates the p38 subfamily of MAPKs, we found that decaging active MKK6 in fibroblasts is sufficient to trigger apoptosis in a p38-dependent manner. Both in fibroblasts and in a murine melanoma cell line expressing mutant B-Raf, MKK6 activation rapidly and potently inhibited the pro-proliferative extracellular signal-regulated kinase (ERK) pathway; to our surprise, this negative cross-regulation was equally robust when all p38 isoforms were inhibited. These results position MKK6 as a new pleiotropic signal transducer that promotes both pro-apoptotic and anti-proliferative signaling, and they highlight the utility of caged, light-activated kinases for dissecting stress-activated signaling networks. [ABSTRACT FROM AUTHOR]

We propose a phase imaging method that combines the Fourier ptychography and compressive sensing theories using single-pixel detection in the spatial spectrum plane. Specifically, the spatial Fourier spectrum is shifted based on the Fourier ptychography theory, and the compressive sensing theory is applied to reduce the amount of acquired data. Further, an algorithm has been developed to reconstruct the phase images and an asymmetric mask introduced to eliminate ghost interference. The feasibility of the proposed method was verified through simulation and evaluated in terms of the compressive sensing theory realized. The results show that a two-dimensional image can be restored at a low sampling rate of 5% using the proposed method. [ABSTRACT FROM AUTHOR]

Biofilms are significant hazards in the food industry. In this study, we investigated the effects of food additive such as citral, cinnamaldehyde, and tea polyphenols on mixed biofilm formation by foodborne Staphylococcus aureus and Salmonella serotype Enteritidis. The adhesion rates of mixed strains in sub-MIC of additives were determined by a microtiter plate assay and bacterial communication signal autoinducer 2 (AI-2) production via a bioluminescence reporter Vibrio harveyi BB170. The structure of mixed biofilm was analyzed using scanning electron microscopy. The effect of the disinfectants hydrogen peroxide, sodium hypochlorite, and peracetic acid was tested on the mixed biofilm. Our results demonstrated that citral, cinnamaldehyde, and tea polyphenols were able to significantly inhibit mixed biofilm formation, while citral could reduce the synthesis of AI-2. Conversely, we observed a significant increase in AI-2 mediated by cinnamaldehyde. Tea polyphenols at lower concentrations induced AI-2 synthesis; however, AI-2 synthesis was significantly inhibited at higher concentrations (300 m g/ml). Food additives inhibited the adhesion of mixed bacteria on stainless steel chips and increased the sensitivity of the mixed biofilm to disinfectants. In conclusion, citral, cinnamaldehyde, and tea polyphenols had strong inhibitory effects on mixed biofilm formation and also enhanced the effect of disinfectant on mixed biofilm formation. This study provides a scientific basis for the application of natural food additives to control biofilm formation of foodborne bacteria. [ABSTRACT FROM AUTHOR]

The refractive index of blood is a key biophysical parameter, which can reflect the physiological state. We measured the refractive index of whole blood and other components, such as serum, plasma, and hemoglobin, based on internal reflection by using a homemade apparatus in the spectral range of 400 to 750 nm. In addition to the hemoglobin solution, which has a Soret band about 420 nm and two Q-bands between 500 and 600 nm, the measurements of other samples are the normal dispersion curve. The results are approximated by the Cauchy equation and Sellmeier equation, and the correlation coefficients are more than 0.997. [ABSTRACT FROM AUTHOR]

We investigated the effect of thiazone, a widely used penetration enhancer, on in vitro porcine skin and muscle tissue by single-integrating sphere technique during optical clearing (OC) treatment. The results showed that thiazone induced an increase on the total transmittance of skin which led to a reduction in that of muscle in the spectral range from 400 to 800 nm. Small particles crystalized out from the thiazone-treated muscle were observed by microscopy imaging. With the help of x-ray diffraction measurement, we ascertained that the crystal was a single-crystal of thiazone, which mainly induced an increase of the scattering. Contrast transmittance measurements carried on the mixture of water, thizaone–propylene glycol solution showed that the free water in muscle could be the main reason for the thiazone crystallization. Therefore, during OC treatment of thiazone, the remarkable effect on skin and the noticeable inhibition effect on subcutaneous muscle tissue after penetrating into the skin should be considered. The experimental results provide such a reference for the choice of penetration enhancer. [ABSTRACT FROM AUTHOR]

We propose a simple and cost-effect method, current-stimulus dielectric breakdown, to manipulate the 3D shapes of the nanochannels in 20-nm-thick SiNx membranes. Besides the precise control of nanopore size, the cone orientation can be determined by the pulse polarity. The cone angle of nanopores can be systematically tuned by simply changing the stimulus pulse waveform, allowing the gradual shape control from conical to obconical. After they are formed, the cone angle of these nanopores can be further tuned in a certain range by adjusting the widening pulse. Such size and 3D shape controllable abiotic nanopores can construct a constriction in the nanochannel and hence produce a sub-nm "sensing zone" to suit any desired bio-sensing or precise DNA sequencing. Using these conical nanopores, 20-nt ssDNA composed of homopolymers (poly(dA)20, poly(dC)20, and poly(dT)20) can be clearly differentiated by their ionic current signals. [ABSTRACT FROM AUTHOR]

The complex refractive index dispersion (CRID), which contains the information on the refractive index dispersion and extinction coefficient spectra, is an important optical parameter of biotissue. However, it is hard to perform the CRID measurement on biotissues due to their high scattering property. Continuous CRID measurement based on internal reflection (CCRIDM-IR) is introduced. By using a lab-made apparatus, internal reflectance spectra of biotissue samples at multiple incident angles were detected, from which the continuous CRIDs were calculated based on the Fresnel formula. Results showed that in 400- to 750-nm range, hemoglobin solution has complicated dispersion and extinction coefficient spectra, while other biotissues have normal dispersion properties, and their extinction coefficients do not vary much with different wavelengths. The normal dispersion can be accurately described by several coefficients of dispersion equations (Cauchy equation, Cornu equation, and Conrady equation). To our knowledge, this is the first time that the continuous CRID of scattering biotissue over a continuous spectral region is measured, and we hereby have proven that CCRIDM-IR is a good method for continuous CRID research of biotissue. [ABSTRACT FROM AUTHOR]

The physical changes of tissue are complicated to evaluate during optical clearing (OC) treatment. Monitoring the changes of optical parameters, including the complex refractive index (CRI), helps people better understand the OC process. From the imaginary part of CRI, we can deduce the extinction coefficient of tissue. Based on the total internal reflection method, the time-dependent CRI of porcine muscle during natural dehydration is well determined. Results show that the real RI increases continuously with the increase of dehydration time, whereas the extinction coefficient initially increases and then decreases. Finally, the extinction coefficient becomesmuch smaller than the initial value, which demonstrates that better tissue optical clarity is obtained. The change tendency of the extinction coefficient of tissue is used to qualitatively explain the dynamic change of transmittance of a natural dehydrated tissue. Consequently, CRI, especially its imaginary part, is a very useful optical parameter by which to evaluate the OC effect. [ABSTRACT FROM AUTHOR]

Traditionally, continuous refractive index dispersion (CRID) measurement of materials with scattering is hard to realize. In this paper, CRID measurement based on the derivative total reflection method (CRIDM-DTRM) is proposed to measure the CRID of both absorption and scattering materials. It effectively determined the CRID of K9 glass, concentrated milk, and 0.5% methyl red solution in the 400-750 nm range with the spectral resolution of about 0.259 nm. For the first time, CRID of a scattering material is measured. CRIDM-DTRM is a useful technique in the field of RID measurement, especially for biotissues and anomalous dispersion materials. [ABSTRACT FROM AUTHOR]

The refractive-index profile (RIP) of optical fibers is of fundamental significance in determining critical fiber properties. Here, we present the application of a two-dimensional (2-D) scanning focused refractive-index microscopy (SFRIM) to accurately obtain the 2-D RIP of a graded-index optical fiber. Some modifications are made to SFRIM for better 2-D measurement. Quantitative RIP of the fiber is obtained with derivative total reflection method. The refractive-index accuracy is 0.002. The measured result is in good agreement with theoretical expectation. This method is straightforward, simple, repeatable, and free from signal distortion. This technique is suitable for symmetric and asymmetric optical fibers. The results indicate that this technique can be applied to obtain the RIPs of a wide range of materials and has broad application prospect in many fields. [ABSTRACT FROM AUTHOR]

We report the dynamic refractive index (RI) change of tissue under a stepped compression load using a custom-built pressure apparatus. Angle-dependent reflectance profiles of biotissue samples are recorded, and the RI values are resolved using the derivative total reflection method. These results are relevant for understanding the mechanism of mechanical optical clearing, for investigating tissue dynamics under mechanical stimuli, and for other biomedical applications. [ABSTRACT FROM AUTHOR]

Objective: The aims of the present paper were to assess the nutritional status of children under 5 years old using the 2006 WHO Child Growth Standards ('the WHO standards') and to compare the results with those obtained using the National Center for Health Statistics/WHO international growth reference ('the NCHS reference'). Design: This was a community-based cross-sectional survey. The WHO standards were used to calculate Z-scores of height-for-age (HAZ), weight-for-age (WAZ), weight-for-height (WHZ) and BMI-for-age (BMIZ). Setting: Fifty counties of thirteen mid-western provinces, China. Subjects: A total 8041 children aged <5 years were measured during a 2-month period from August to October 2006. Results: The prevalence of stunting, underweight and wasting were 30.2%, 10.2% and 2.9%, respectively. The prevalence of overweight and the possible risk of overweight were as high as 4.1% and 16.8%. Further analysis among the children with possible risk of overweight found that the percentage of stunting (HAZ>22) was 57.6%, the percentage with -22≤HAZ≤2 was 41.0% and the percentage with HAZ>2 was only 1.4%. The prevalence of stunting was 21.9% and of underweight was 12.7% by the NCHS reference. Conclusions: Stunting was the most serious problem that was impeding child growth and development. The high rate of 'overweight' was a false impression, the truth being 'stunting overweight', and the way to solve it should be to increase protein and other nutrients in the diet at an early age. [ABSTRACT FROM AUTHOR]

Non-homogenous material such as solid composite materials examination using refractive index-sensing remains a challenge for researchers. A derivative total reflection method for simultaneous measurement of the refractive indices of various components of a non-homogeneous solid was developed. Only a measurement of the reflectance from the surface of composite sample is necessary. In our experiments, simulation samples, porcine tissue, and Rosso Levanto marble samples were measured to verify proposed method. [ABSTRACT FROM AUTHOR]