The involvement of mitochondrial dysfunction in many pathophysiological conditions and human diseases is well documented. In order to evaluate mitochondrial function in vitro,many experimental systems have been developed. Nevertheless the number of in vivo monitoring systems for the evaluation of mitochondrial activities in intact animals and patients is relatively limited. The pioneering development of the conceptual and technological aspects ofmitochondrial monitoring, in vitro and in vivo, was done by the late Prof. Britton Chance (July 24, 1913-November 16, 2010) since the early 1950s. It was my privilege to join his laboratory in 1972 and collaborate with him for almost four decades. The main achievements of our collaboration are presented in this paper. Our activities included cycles of technology development, followed by its applications to study various pathophysiological conditions. In the initial stage, the first fiber-optic-based NADH fluorometer was developed. This device enabled us to monitor various organs in anesthetized animals aswell as the brain of nonanesthetized small animals. Later on, the addition of various physiological parameters to NADH monitoring enabled us to correlate mitochondrial function with other cellular functions. The application of the developed technology to clinical situations was a major interest of Prof. Chance and indeed this goal was achieved in the last decade.As of today, the basic tool forNADHmonitoring and the large database of results are available for large-scale experimental and clinical applications.

Treatment-induced apoptosis of cancer cells is one goal of cancer therapy. Interestingly, more heat is generated by mitochondria during apoptosis, especially the uncoupled apoptotic state,1,2 compared to the resting state. In this case study, we explore these thermal effects by longitudinally measuring temperature variations in a breast lesion of a pathological complete responder during neoadjuvant chemotherapy (NAC). Diffuse Optical Spectroscopic Imaging (DOSI) was employed to derive absolute deep tissue temperature using subtle spectral features of the water peak at 975 nm.3 A significant temperature increase was observed in time windows during the anthracycline and cyclophosphamide (AC) regimen but not in the paclitaxel and bevacizumab regimen. Hemoglobin concentration changes generally did not follow temperature, suggesting the measured temperature increases were likely due to mitochondrial uncoupling rather than a direct vascular effect. A simultaneous increase of tissue oxygen saturation with temperature was observed, suggesting that oxidative stress also contributes to apoptosis. Although preliminary, this study indicates longitudinal DOSI tissue temperature monitoring provides information that can improve our understanding of the mechanisms of tissue response during NAC.

This article presents a historical perspective of foundational studies utilizing near-infrared spectroscopy (NIRS) to measure the hemodynamics, oxygenation, and activation of the human brain cortex during cognitive tasks, called functional NIRS (fNIRS). It discusses studies representative of the diagnostic power and potential that fNIRS has shown for providing increased understanding of cognitive changes with aging and dementia. It concludes by discussing challenges that continue to confront the implementation of NIRS and fNIRS in clinical and translational research, in particular, the challenges to measure cognitive function and impairment in aged, chronically ill, and fragile subjects with or without dementia. It is written specifically in memoriam, honoring Britton Chance, therefore papers authored by him and his collaborative research family are weighted to illustrate the significant foundation and legacy he has left to this world.

In this paper, we consider the use of blind deconvolution for optoacoustic (photoacoustic) imaging and investigate the performance of the method as means for increasing the resolution of the reconstructed image beyond the physical restrictions of the system. The method is demonstrated with optoacoustic measurement obtained from six-day-old mice, imaged in the near-infrared using a broadband hydrophone in a circular scanning configuration.We find that estimates of the unknown point spread function, achieved by blind deconvolution, improve the resolution and contrast in the images and show promise for enhancing optoacoustic images.

Photosensitive fluorescent probes have become powerful tools in chemical biology and molecular biophysics, which are used to investigate cellular processes with high temporal and spatial resolution. Accordingly, photosensitive fluorescent probes, including photoactivatable, photoconvertible, and photoswitchable fluorophores, have been extensively developed during the past decade. The photoswitchable fluorophores have received much attention because they highlight cellular events clearly. This minireview summarizes recent advances of using reversibly photoswitchable fluorophores and their applications in innovative bioimaging. Photoswitchable fluorophores include photoswitchable fluorescent proteins, photoswitchable fluorescent organic molecules (dyes), and photoswitchable fluorescent nanoparticles. Several strategies have been developed to synthesize photoswitchable fluorophores, including engineering combination proteins, chemical synthesis, polymerization, and self-assembly. Here we concentrate on polymer nanoparticles with optically switchable emission properties: either fluorescence on/off or dualalternating- color fluorescence photoswitching. The essential mechanisms of fluorescence photoswitching enable different types of photoswitchable fluorophores to change emission intensity or wavelength (color) and thus validating the basis of the fluorescence on/off or dual-color photoswitching design. Generally the possible applications of any fluorophores are to label biological targets, followed by specific imaging. The newly developed photoswitchable fluorophores enable super-resolution fluorescence imaging because of their photosensitive emission. Finally, we summarize the important area regarding future research and development on photoswitchable fluorescent nanoparticles.

The use of anesthetics is a well-known treatment for severely injured patients. In the present study we tested the pathophysiology of several levels of injury damage in a rat model and also tested the effect of Equithesin on brain vitality in these models. Traumatic Brain Injury (TBI) was induced using the fluid percussion injury model in four levels: mild, moderate and two levels of severe TBI. Brain real-time evaluation was performed by the multiparametric monitoring assembly (MPA) which enable cerebral blood flow (CBF) monitoring by laser Doppler flowmetry, mitochondrial NADH (Nicotinamide adenine dinucleotide) monitoring by the fluorometric technique, ionic homehostasis using special mini-electrodes, intracranial pressure (ICP) by the ICP camino device and needle electrodes for ECoG (Electrocorticogram) recording. Our results showed high correlation between the level of impact and the extent of changes in the physiological properties of the injury as indicated by the changes in all parameters monitored using the MPA device. Moreover, Equithesin improved CBF, ionic extracellular level and mitochondrial redox state following mild and moderate TBI while in severe TBI, Equithesin did not improve the metabolic state of the cerebral cortex, although it decreased the mortality rate from 66% to 20%, and following extra-severe TBI level, Equithesin did not improve survival rate. In conclusion it seems that Equithesin's protective effect exists under mild to moderate levels of injury and not in case of severe injuries.

The lag (latency) time (LT) is known in dermatology clinic as an asymptomatic period till the development of skin eruptions. In the laboratory, the LT might determine the interval from \zero" point until the peak(s) of changes in measured laboratory parameter during the performed test. This paper discusses methodological and technical aspects of precise measurement of the LT in the living healthy and pathological skin by laser and optical technologies through clinical and experimental applications in dermatology. Based on a dynamics approach to measure, calculate and interpret the LT in blood and in interstitial fluid compartments of the skin tissue, this method has a potential to promote deeper understanding of the role of complex dynamic processes in the skin at a level of a molecule, and/or an organ in a whole organism. The method of the LT measurement in vivo also promotes new understanding of (patho)physiological, diagnostic and pharmacological aspects of certain dynamic skin lesions and dynamic complex processes that happen in the skin. Utilized laser and optical techniques showed high reliability and objectivity in collecting data from rapidly changed skin lesions and processes, demonstrating the LT measurement as a very easy-to-use calculation procedure with high informativity, which is extremely important for the clinical and laboratory environment.

Photodynamic therapy based on photogeneration of cytotoxic singlet oxygen and following oxidative stress is currently used in neuro-oncology for destruction of brain tumors. However, along with a tumor, it damages healthy neurons and glial cells. We studied the involvement of the glutamate-related signaling pathway in photodynamic damage to normal glial cells in the crayfish stretch receptor. This model object consists of a single neuron surrounded by glial cells. It was photosensitized with alumophthalocyanine Photosens and irradiated by the diode laser (670 nm). Application of enzyme inhibitors and ion channels modulators showed that exogenous L-glutamate decreased photoinduced apoptosis of crayfish glial cells. The natural neuroglial mediator N-acetylaspartylglutamate, which releases glutamate after splitting by glutamate carboxypeptidase II, also inhibited photoinduced apoptosis. Inhibition of glutamate carboxypeptidase II, oppositely, enhanced glial apoptosis. This confirmed the antiapoptotic activity of glutamate. Glutamate agonist NMDA or inhibitor of NMDA receptors MK801 did not influence photodynamic death of glial cells, i.e., these receptors did not participate in glial apoptosis. Inhibition of metabotropic glutamate receptors mGluRI with AP-3 reduced PDT-induced apoptosis of glial cells. Thus, chemical modifiers of various signaling processes can modulate photoinduced necrosis or apoptosis of glial cells and thus modify efficiency of photodynamic therapy.

The goal of this work was to evaluate the safety and efficacy of the Red Light Emitted Toothbrush (R-LETB) emitting at wavelength of 663 nm with power density of 3.3mW/cm² in combination with 0.1%-methylene blue (MB) solution for the reduction of plaque and treatment of gingivitis. A microbiological in vitro study and a pilot clinical study were conducted. The microbiological study has shown total suppression of pathogenic flora after a 3-min exposure to the dye solution followed by a 20-sec treatment with the R-LETB. For the clinical study, 37 subjects of both sexes with gingivitis were enrolled and randomly assigned to one of two groups. Subjects in the first (treatment) group were instructed to rinse their mouth with MB solution provided for 1 min and then brush the teeth with the R-LETB and standardized toothpaste. The second (control) group used only the toothpaste and a regular toothbrush. Subjects in both groups followed their respective procedures 2 times a day (morning and evening) for 30 days. Indices of plaque, gingival bleeding, and inflammation were evaluated at 14-day and 30-day timepoints. In the both groups, all indices improved in comparison with baseline. However, the treatment group demonstrated more pronounced improvement of the studied indices that was attributed to additional anti-microbial action of red light and MB on gum tissue. Thus, the use of R-LETB with MB appears to have a multifactor therapeutic action on oral pathological microflora: mechanical removal of the bacteria and suppressing action on microorganisms due to photodynamic reaction.

Segmenting the Dynamic Contrast-Enhanced Breast Magnetic Resonance Images (DCE-BMRI) is an extremely important task to diagnose the disease because it has the highest specificity when acquired with high temporal and spatial resolution and is also corrupted by heavy noise, outliers, and other imaging artifacts. In this paper, we intend to develop efficient robust segmentation algorithms based on fuzzy clustering approach for segmenting the DCE-BMRs. Our proposed segmentation algorithms have been amalgamated with effective kernel-induced distance measure on standard fuzzy c-means algorithm along with the spatial neighborhood information, entropy term, and tolerance vector into a fuzzy clustering structure for segmenting the DCE-BMRI. The significant feature of our proposed algorithms is its capability to find the optimal membership grades and obtain effective cluster centers automatically by minimizing the proposed robust objective functions. Also, this article demonstrates the superiority of the proposed algorithms for segmenting DCE-BMRI in comparison with other recent kernel-based fuzzy c-means techniques. Finally the clustering accuracies of the proposed algorithms are validated by using silhouette method in comparison with existed fuzzy clustering algorithms.

To characterize the degree of similarity inherent to parameters of the optically uniaxial birefringent protein-fibril networks of biological tissues, a new parameter — complex degree of mutual anisotropy — has been offered. The technique of polarization measuring the coordinate distributions of the complex degree of mutual anisotropy of biological tissues has been developed. It has been shown that statistical approach to the analysis of complex degree of mutual anisotropy distributions for biological tissues in various morphological and physiological states and for different optical thicknesses appears to be more sensitive and efficient in differentiation of physiological state, as compared to investigations of complex degree of mutual polarization in the corresponding laser images.

Britton Chance has been a person of superlative quality, a close friend, a great teacher and researcher, and a well-known and revered scientist in biochemistry.

I had been closely working with Dr. Britton Chance from 2005-2010 on imaging mitochondrial redox state in cancer and stem cells. I had also learned much from him in daily work and personal life. Here I would like to share some of my memories and experiences including (1) Great science is not necessarily done with top-grade expensive instruments; (2) Brit was genuinely interested in and dedicated to science; (3) Brit's attention to detail and timely action; (4) Brit's open-mindedness; and (5) Brit being modest, appreciative, and caring for others.

This article briefly reflects some of my interactions with Dr. Britton Chance (BC), from a perspective of his graduate student.