The mitochondrial redox state and its heterogeneity of colon cancer at tissue level have not been previously reported. Nor has how p53 regulates mitochondrial respiration been measured at (deep) tissue level, presumably due to the unavailability of the technology that has sufficient spatial resolution and tissue penetration depth. Our prior work demonstrated that the mitochondrial redox state and its intratumor heterogeneity is associated with cancer aggressiveness in human melanoma and breast cancer in mouse models, with the more metastatic tumors exhibiting localized regions of more oxidized redox state. Using the Chance redox scanner with an inplane spatial resolution of 200 μm, we imaged the mitochondrial redox state of the wild-type p53 colon tumors (HCT116 p53 wt) and the p53-deleted colon tumors (HCT116 p53-=-) by collecting the fluorescence signals of nicotinamide adenine dinucleotide (NADH) and oxidized flavoproteins [Fp, including flavin adenine dinucleotide (FAD)] from the mouse xenografts snap-frozen at low temperature. Our results show that: (1) both tumor lines have significant degree of intratumor heterogeneity of the redox state, typically exhibiting a distinct bi-modal distribution that either correlates with the spatial core-rim pattern or the "hot/cold" oxidation-reduction patches; (2) the p53-=- group is significantly more heterogeneous in the mitochondrial redox state and has a more oxidized tumor core compared to the p53 wt group when the tumor sizes of the two groups are matched; (3) the tumor size dependence of the redox indices (such as Fp and Fp redox ratio) is significant in the p53-=- group with the larger ones being more oxidized and more heterogeneous in their redox state, particularly more oxidized in the tumor central regions; (4) the H&E staining images of tumor sections grossly correlate with the redox images. The present work is the first to reveal at the submillimeter scale the intratumor heterogeneity pattern of the mitochondrial redox state in colon cancer and the first to indicate that at tissue level the mitochondrial redox state is p53 dependent. The findings should assist in our understanding on colon cancer pathology and developing new imaging biomarkers for clinical applications.

Accepted 2 May 2013 Published 18 June 2013 Reactive oxygen species (ROS) have been implicated in the pathogenesis of many acute and chronic pulmonary disorders such as acute lung injury (ALI) in adults and bronchopulmonary dysplasia (BPD) in premature infants. Bacterial infection and oxygen toxicity, which result in pulmonary vascular endothelial injury, contribute to impaired vascular growth and alveolar simplification seen in the lungs of premature infants with BPD. Hyperoxia induces ALI, reduces cell proliferation, causes DNA damage and promotes cell death by causing mitochondrial dysfunction. The objective of this study was to use an optical imaging technique to evaluate the variations in fluorescence intensities of the auto-fluorescent mitochondrial metabolic coenzymes, NADH and FAD in four different groups of rats. The ratio of these fluorescence signals (NADH/ FAD), referred to as NADH redox ratio (NADH RR) has been used as an indicator of tissue metabolism in injuries. Here, we investigated whether the changes in metabolic state can be used as a marker of oxidative stress caused by hyperoxia and bacterial lipopolysaccharide (LPS) exposure in neonatal rat lungs. We examined the tissue redox states of lungs from four groups of rat pups: normoxic (21% O²) pups, hyperoxic (90% O²) pups, pups treated with LPS (normoxic +LPS), and pups treated with LPS and hyperoxia (hyperoxic + LPS). Our results show that hyperoxia oxidized the respiratory chain as reflected by a ~31% decrease in lung tissue NADH RR as compared to that for normoxic lungs. LPS treatment alone or with hyperoxia had no significant effect on lung tissue NADH RR as compared to that for normoxic or hyperoxic lungs, respectively. Thus, NADH RR serves as a quantitative marker of oxidative stress level in lung injury caused by two clinically important conditions: hyperoxia and LPS exposure.

The results of singular approach usage in the tasks of description and classification of appearance of optical anisotropy of different types of phase-inhomogeneous biological layers (surfacescattering, optically thin and optically thick) have been presented. The characteristic values of the fourth Stokes vector parameter (S₄ = 0 — linear polarization — (L-state); S₄ = ±1 — circular polarization — (±C-state)) have been chosen as the main analytical tool describing polarization-singular states. The value of S₄ has been determined by the value of phase shift between the orthogonal components of amplitude in the point of biological layer laser image and therefore is azimuthally stable. Hence, statistic moments of the first to the fourth orders characterizing the distribution of the amount of characteristic values S₄ = 0; S₄ = ±1 have been used for definition and differentiation of optical properties of different types of biological layers — surface scattering, optically thin and optically thick human skin.

The wireless distributed acquisition system for near infrared spectroscopy (WDA-NIRS) is a portable, ultra-compact, continuous wave (CW) NIRS system. Its main advantage is that it allows continuous synchronized multi-site hemodynamic monitoring. The WDA-NIRS system calculates online changes in hemoglobin concentration based on modified Beer-Lambert law and the tissue oxygenation index based on the spatial-resolved spectroscopy method. It consists of up to seven signal acquisition units, sufficiently small to be easily attached to any part of the body. These units are remotely synchronized by a PC base station for independent acquisition of NIRS signals. Each acquisition module can be freely adapted to individual requirements such as local skin properties and the microcirculation of interest, e.g., different muscles, brain, skin, etc. For this purpose, the light emitted by each LED can be individually, interactively or automatically adjusted to local needs. Furthermore, the user can freely create an emitter time-multiplexing protocol and choose the detector sensitivity most suitable to a particular situation. The potential diagnostic value of this advanced device is demonstrated by three typical applications.

Intrinsic optical changes that follow infundibular stalk stimulation of the neurointermediate lobe of the mouse pituitary gland exhibit three different phases that reflect three distinct physiological events. The first (E-wave) is the rapid light-scattering increase that is associated with a nerve terminal volume increase (mechanical spike), and that accompanies excitation of the neurohypophysial terminals by the invading action potential; the second (S-wave) is the slower lightscattering decrease that is tightly correlated with the secretion of the peptide hormones oxytocin and arginine vasopressin, and the third is the long-duration response (R-wave) that reflects cell volume changes in the pars intermedia. We have studied the E-wave and the S-wave in earlier publications. The R-wave, considered here, is sensitive to chloride replacement as well as to blockade of chloride channels. By blocking GABAA receptors (which are ligand-gated chloride channels) with pharmacological agents, and by applying GABA directly into the bathing solution, or evoking its release from GABAergic inputs, we have demonstrated that this long-duration optical response is sensitive to chloride movements and reflects GABA-induced changes in the intrinsic optical properties of the pars intermedia. The full time-course of this optical response takes minutes and, therefore, has to embody some other process (or processes) related to the restoration of resting physiological chloride concentrations, following the opening and closing of GABAA-receptor channels. Here we demonstrate that the shape of the R-wave, the long-lasting light-scattering signal, is indeed affected by the activity of GAT1, one of the sodium- and chloride-dependent GABA transporters.

Mn co-precipitation method combined with Raman spectroscopy were used to determine trace heavy metals (copper, zinc, cadmium and lead) in water sample. Different concentrations of heavy metals including copper, zinc, cadmium and lead in water samples were separated and enriched by Mn2t-phen-SCN- ternary complex co-precipitation procedure. The Raman spectra of co-precipitation sediments were collected using confocal micro-Raman spectrometry. Different preprocessing treatments and regression calibration methods were compared. The best models using partial least squares regression (PLS) of copper, zinc, cadmium and lead were built with a correlation coefficient of prediction (Rp) of 0.979, 0.964, 0.956 and 0.972, respectively, and the root mean square error of prediction (RMSEP) of 6.587, 9.046, 9.998 and 7.751 μg/kg, respectively. The co-precipitation procedure combined with Raman spectroscopy method are feasible to detect the amount of heavy metals in water.

Osteoarthritis (OA), one of the most common joint diseases with unknown etiology, is characterized by the progressive destruction of articular cartilage and the apoptosis of chondrocytes. The purpose of this study is to elucidate the molecular mechanisms of H₂O₂-mediated rabbit chondrocytes apoptosis. CCK-8 assay showed that H₂O₂ treatment induced a remarkable reduction of cell viability, which was further verified by the remarkable phosphatidylserine externalization after H₂O₂ treatment for 1 h, the typical characteristics of apoptosis. H₂O₂ treatment induced a significant dysfunction of mitochondrial membrane potential (ΔΨm), but did not induce casapse- 9 activation, indicating that H₂O₂ treatment induced caspase-independent intrinsic apoptosis that was further verified by the fact that silencing of AIF but not inhibiting caspase-9 potently prevented H₂O₂-induced apoptosis. H₂O₂ treatment induced a significant increase of caspase-8 and -3 activation, and inhibition of caspase-8 or -3 significantly prevented H₂O₂-induced apoptosis, suggesting that the extrinsic pathway played an important role. Collectively, our findings demonstrate that H₂O₂ induces apoptosis via both the casapse-8-mediated extrinsic and the caspase-independent intrinsic apoptosis pathways in rabbit chondrocytes.

In experiments on newborn rats with stress-related intracranial hemorrhage (ICH) using Doppler optical coherence tomography (DOCT) we have shown that latent stage of ICH (4 h after stress) is characterized by decrease of venous blood outflow and the loss of sensitivity of sagittal vein to vasoconstrictor effect of adrenaline. The incidence of ICH (24 h after stress) was accompanied by progression of early pathological changes in cerebral venous blood flow (CVBF) and development of venous insufficiency. Taking into consideration of this fact, we suggest that the suppression of CVBF related to the severity to the deleterious effect of stress on the brain hemodynamics in newborn rats. These facts allow us to conclude that the venous insufficiency with the loss of vasoconstrictor response to adrenaline is an informative and sensitive component of pattern of CVBF that can be important diagnostic criteria of risk of ICH development in newborns.

Elastic cartilage in the rabbit external ear is an important animal model with attractive potential value for researching the physiological and pathological states of cartilages especially during wound healing. In this work, nonlinear optical microscopy based on two-photon excited fluorescence and second harmonic generation were employed for imaging and quantifying the intact elastic cartilage. The morphology and distribution of main components in elastic cartilage including cartilage cells, collagen and elastic fibers were clearly observed from the high-resolution two-dimensional nonlinear optical images. The areas of cell nuclei, a parameter related to the pathological changes of normal or abnormal elastic cartilage, can be easily quantified. Moreover, the three-dimensional structure of chondrocytes and matrix were displayed by constructing three-dimensional image of cartilage tissue. At last, the emission spectra from cartilage were obtained and analyzed. We found that the different ratio of collagen over elastic fibers can be used to locate the observed position in the elastic cartilage. The redox ratio based on the ratio of nicotinamide adenine dinucleotide (NADH) over flavin adenine dinucleotide (FAD) fluorescence can also be calculated to analyze the metabolic state of chondrocytes in different regions. Our results demonstrated that this technique has the potential to provide more accurate and comprehensive information for the physiological states of elastic cartilage.

Accepted 22 June 2013 Published 24 July 2013 We apply different polarization imaging techniques for cancerous liver tissues, and compare the relative contrasts for difference polarization imaging (DPI), degree of polarization imaging (DOPI) and rotating linear polarization imaging (RLPI). Experimental results show that a number of polarization imaging parameters are capable of differentiating cancerous cells in isotropic liver tissues. To analyze the contrast mechanism of the cancer-sensitive polarization imaging parameters, we propose a scattering model containing two types of spherical scatterers and carry on Monte Carlo simulations based on this bi-component model. Both the experimental and Monte Carlo simulated results show that the RLPI technique can provide a good imaging contrast of cancerous tissues. The bi-component scattering model provides a useful tool to analyze the contrast mechanism of polarization imaging of cancerous tissues.

The diagnosis of bacterial infections remains a major challenge in medicine. Optical imaging of bacterial infection in living animals is usually conducted with genetic reporters such as lightemitting enzymes or fluorescent proteins. However, there are many circumstances where genetic reporters are not applicable, and there is an urgent need for exogenous synthetic probes that can selectively target bacteria. Optical imaging of bacteria in vivo is much less developed than methods such as radioimaging and MRI. Furthermore near-infrared (NIR) dyes with emission wavelengths in the region of 650·900 nm can propagate through two or more centimeters of tissue and may enable deeper tissue imaging if sensitive detection techniques are employed. Here we constructed an antimicrobial peptide fragment UBI29-41-based near-infrared fluorescent imaging probe. The probe is composed of UBI29-41 conjugated to a near infrared dye ICG-Der- 02. UBI29-41 is a cationic antimicrobial peptide that targets the anionic surfaces of bacterial cells. The probe allows detection of Staphylococcus aureus infection (5×10⁷cells) in a mouse local infection model using whole animal near-infrared fluorescence imaging. Furthermore, we demonstrate that the UBI29-41-based imaging probe can selectively accumulate within bacteria. The significantly higher accumulation in bacterial infection suggests that UBI29-41-based imaging probe may be a promising imaging agent to detect bacterial infections.

We demonstrate the feasibility of simultaneous multi-probe detection for an optical-resolution photoacoustic microscopy (OR-PAM) system. OR-PAM has elicited the attention of biomedical imaging researchers because of its optical absorption contrast and high spatial resolution with great imaging depth. OR-PAM allows label-free and noninvasive imaging by maximizing the optical absorption of endogenous biomolecules. However, given the inadequate absorption of some biomolecules, detection sensitivity at the same incident intensity requires improvement. In this study, a modulated continuous wave with power density less than 3mW/cm² (1/4 of the ANSI safety limit) excited the weak photoacoustic (PA) signals of biological cells. A microcavity transducer is developed based on the bulk modulus of gas five orders of magnitude lower than that of solid; air pressure variation is inversely proportional to cavity volume at the same temperature increase. Considering that a PA wave expands in various directions, detecting PA signals from different positions and adding them together can increase detection sensitivity and signal-to-noise ratio. Therefore, we employ four detectors to acquire tiny PA signals simultaneously. Experimental results show that the developed OR-PAM system allows the label-free imaging of cells with weak optical absorption.