Carotenoids are known to play an important role in health and disease state of living human tissue based on their antioxidant and optical filtering functions. In this study, we show that carotenoids exist in human bone and surrounding fatty tissue both in significant and individually variable concentrations. Measurements of biopsied tissue samples with molecule-specific Raman spectroscopy and high-performance liquid chromatography reveal that all carotenoids that are known to exist in human skin are also present in human bone. This includes all carotenes, lycopene, β -cryptoxanthin, lutein, and zeaxanthin. We propose quantitative reflection imaging as a noncontact optical method suitable for the measurement of composite carotenoid levels in bone and surrounding tissue exposed during open surgeries such as total knee arthroplasty, and as a proof of concept, demonstrate carotenoid measurements in biopsied bone samples. This will allow one to establish potential correlations between internal tissue carotenoid levels and levels in skin and to potentially use already existing optical skin carotenoid tests as surrogate marker for bone carotenoid status.
Two major carotenoids species found in salmonids muscle tissues are astaxanthin and cantaxanthin. They are taken up from fish food and are responsible for the attractive red-orange color of salmon filet. Since carotenoids are powerful antioxidants and biomarkers of nutrient consumption, they are thought to indicate fish health and resistance to diseases in fish farm environments. Therefore, a rapid, accurate, quantitative optical technique for measuring carotenoid content in salmon tissues is of economic interest. We demonstrate the possibility of using fast, selective, quantitative detection of astaxanthin and cantaxanthin in salmon muscle tissues, employing resonance Raman spectroscopy. Analyzing strong Raman signals originating from the carbon-carbon double bond stretch vibrations of the carotenoid molecules under blue laser excitation, we are able to characterize quantitatively the concentrations of carotenoids in salmon muscle tissue. To validate the technique, we compared Raman data with absorption measurements of carotenoid extracts in acetone. A close correspondence was observed in absorption spectra for tissue extract in acetone and a pure astaxanthin solution. Raman results show a linear dependence between Raman and absorption data. The proposed technique holds promise as a method of rapid screening of carotenoid levels in fish muscle tissues and may be attractive for the fish farm industry to assess the dietary status of salmon, risk for infective diseases, and product quality control.
Increasing evidence points to the beneficial effects of carotenoid antioxidants in the human body. Several studies, for example, support the protective role of lutein and zeaxanthin in the prevention of age-related eye diseases. If present in high concentrations in the macular region of the retina, lutein and zeaxanthin provide pigmentation in this most light sensitive retinal spot, and as a result of light filtering and/or antioxidant action, delay the onset of macular degeneration with increasing age. Other carotenoids, such as lycopene and beta-carotene, play an important role as well in the protection of skin from UV and short-wavelength visible radiation. Lutein and lycopene may also have protective function for cardiovascular health, and lycopene may play a role in the prevention of prostate cancer. Motivated by the growing importance of carotenoids in health and disease, and recognizing the lack of any accepted noninvasive technology for the detection of carotenoids in living human tissue, we explore resonance Raman spectroscopy as a novel approach for noninvasive, laser optical carotenoid detection. We review the main results achieved recently with the Raman detection approach. Initially we applied the method to the detection of macular carotenoid pigments, and more recently to the detection of carotenoids in human skin and mucosal tissues. Using skin carotenoid Raman instruments, we measure the carotenoid response from the stratum corneum layer of the palm of the hand for a population of 1375 subjects and develope a portable skin Raman scanner for field studies. These experiments reveal that carotenoids are a good indicator of antioxidant status.
Carotenoids are an important part of the antioxidant system in human skin. Carotenoid molecules, provided by fruits and vegetables, are potent free radical quenchers that accumulate in the body. If not balanced by carotenoids and other antioxidants, free radicals may cause premature skin aging, oxidative cell damage, and even skin cancers. As carotenoids depletion may predispose a person to cancer or other disease, rapid and noninvasive measurement of carotenoid level in skin may be of preventive or diagnostic help. At the very least, such measurement can be used to obtain a biomarker for healthy levels of fruit and vegetable consumption. Recently we have developed noninvasive optical technique based on Raman spectroscopy. In this paper we describe compact optical detector for clinical applications that utilizes two-wavelength excitation. It selectively measures the two most prominent skin carotenoids found in the human skin, lycopene and carotenes. According to the medical literature, these two compounds may play different roles in the human body and be part of different tissue defense mechanisms. Dual-wavelength Raman measurements reveal significant differences in the carotenoid composition of different subjects.
Raman detection of macular pigments (MP) holds promise as a novel noninvasive technology for the quantification of lutein and zeaxanthin carotenoids, which are thought to prevent or delay the onset of age-related macular degeneration. Using resonant excitation in the visible, we measure the Raman signals that originate from the double-bond stretch vibrations of the p-conjugated carotenoid molecule's carbon backbone. In this paper we describe the construction and performance of a new, compact, and low-cost MP Raman instrument using dielectric, angle-tuned band-pass filters for wavelength selection and single-channel photo-multiplier detection of carotenoid Raman responses. MP concentration measurements are fast and accurate, as seen in experiments with model eyes and living human eyes. The ease and rapidity of Raman MP measurements, the relative simplicity of the instrumentation, the high accuracy of the measurements, and the lack of significant systematic errors should make this technology useful for widespread clinical research.
The carotenoids lycopene and beta-carotene are powerful antioxidants in skin and are thought to act as scavengers for free radicals and singlet oxygen. The role of carotenoid species in skin health is of strong current interest. We demonstrate the possibility to use Resonance Raman spectroscopy for fast, non-invasive, highly specific, and quantitative detection of beta-carotene and lycopene in human skin. Analyzing Raman signals originating from the carbon-carbon double bond stretch vibrations of the carotenoid molecules under blue and green laser excitation, we were able to characterize quantitatively the relative concentrations of each carotenoid species in-vivo. In the selective detection, we take advantage of different Raman cross-section spectral profiles for beta-carotene and lycopene molecules, and obtain a quantitative assessment of individual long-chain carotenoid species in the skin rather than their cumulative levels. Preliminary dual-wavelength Raman measurements reveal significant differences in the carotenoid composition of different subjects. The technique holds promise for rapid screening of carotenoid compositions in human skin in large populations and may be suitable in clinical studies for assessing the risk for cutaneous diseases.
The predominant long-chain carotenoids found in the human skin are lycopene and β-carotene. They are powerful antioxidants and thought to act as scavengers for free radicals and single oxygen that are formed by excessive exposure of skin to sunlight. However the role of the particular representatives of the carotenoid antioxidants family in the skin defense mechanism is still unclear and has to be clarified. We demonstrate the opportunity for fast non-invasive selective quantitative detection of β-carotene and lycopene in human skin employing Raman spectroscopy. Analyzing Raman signals originating from the carbon-carbon double bond stretch vibrations of the molecules under blue and green laser excitation we were able to characterize quantitativly the concentrations of each carotenoid in alive human skin. In this method we take an advantage of different Raman cross-section spectral profile for β-carotene and lycopene molecules. This novel technique allows the quantitative assessment of individual carotenoid species in the skin rather then the cumulative level of long-chain carotenoids mixture as we could measure in our previous works. The required laser light exposure levels are well within safety standards. Prelimininary dichoromatic Raman measurements reveal significant differences in the carotenoid composition of different volunteer's skin: even in statistically small group of seven subjects the ratio of β-carotene-to-lycopene in their skin vary from 0.5 to 1.6. This technique holds promise as a method of rapid screening of carotenoids composition of human skin in large populations and suitable in clinical studies for assessing the risk for cutaneous diseases.
Carotenoid antioxidants form an important part of the human body's anti-oxidant system and are thought to play an important role in disease prevention. Studies have shown an inverse correlation between high dietary intake of carotenoids and risk of certain cancers, heart disease and degenerative diseases. For example, the carotenoids lutein and zeaxanthin, which are present in high concentrations in the human retina, are thought to prevent age-related macular degeneration, the leading cause of blindness in the elderly in the Western world. We have developed various clinical prototype instruments, based on resonance Raman spectroscopy, that are able to measure carotenoid levels directly in the tissue of interest. At present we use the Raman technology to quantify carotenoid levels in the human retina, in skin, and in the oral cavity. We use resonant excitation of the π-conjugated molecules in the visible wavelength range and detect the molecules' carbon-carbon stretch frequencies. The spectral properties of the various carotenoids can be explored to selectively measure in some cases individual carotenoid species linked ot the prevention of cancer, in human skin. The instrumentation involves home-built, compact, high-throughput Raman systems capable of measuring physiological carotenoid concentrations in human subjects rapidly and quantitatively. The instruments have been demonstrated for field use and screening of tissue carotenoid status in large populations. In Epidemiology, the technology holds promise as a novel, noninvasive and objective biomarker of fruit and vegetable uptake.
Clinical studies of carotenoid macular pigments (MP) and chronic retina disease have been limited by the lack of non-invasive, objective techniques. In this paper we describe anovel, noninvasive optical techniques based on the resonant Raman spectroscopy for the assessment of the carotenoid status of human retina in vivo. Using resonant excitation in the visible, we measure the Raman signals that originate from the single- and double-bond stretch vibrations of the π-conjugated carotenoid molecule's carbon backbone. MP Raman detector, robust device useful for routine measurements of MP concentration in a clinical setting, has been developed and tested in clinical studies in humans to validate its function and to begin to establish its role as a possible screening test for macular pathologies. We report our first results on using carotenoid Raman detection in imaging mode. The results on retinal Raman imaging reveal highly specific and quantitative information regarding the spatial distribution of macular pigments. We also compare Raman technology with others availabe today subjective and objective MP detection methods and show that Raman spectroscopic technology has tremendous potential as a breakthrough method for rapid screening of carotenoid antioxidant levels in large populations that are at risk for vision loss from age-related macular degeneration, the leading cause of blindness of the elderly in the developed world.
We have expanded our efforts to generate high spatial resolution images showing the distibution of carotenoid macular pigments in the human retina using Raman spectroscopy. A low level of macular pigments is associated with an increased risk of developing age-related macular degeneration, a leading cause of irreversible blindness. Using excised human eyecups and resonant excitation of the pigment molecules with narrow bandwidth blue light from a filtered arc lamp, we record Raman images originating from the carbon-carbon double bond stretch vibrations of lutein and zeaxanthin, the carotenoids comprising human macular pigments. Our Raman images reveal significnt differences among subjects, both in regard to absolute levels ss well as spatial distribution within the macula. Since the light levels used to obtain these images are well below established ssafety limits, this technique holds promise for developing a rapid screening diagnostic in large populations at risk for vision loss from age-realted macular degeneration.
We have generated high spatial resolution images showing the distribution of carotenoid macular pigments in the human retina using Raman spectroscopy. A low level of macular pigments is associated with an increased risk of developing age-related macular degeneration, a leading cause of irreversible blindness. Using excised human eyecups and resonant excitation of the pigment molecules with narrow bandwidth blue light from a mercury arc lamp, we record Raman images originating from the carbon-carbon double bond stretch vibrations of lutein and zeaxanthin, the carotenoids comprising human macular pigments. Our Raman images reveal significant differences among subjects, both in regard to absolute levels as well as spatial distribution within the macula. Since the light levels used to obtain these images are well below established safety limits, this technique holds promise for developing a rapid screening diagnostic in large populations at risk for vision loss from age-related macular degeneration.
We have used resonant Raman scattering as a novel, non- invasive, in-vivo optical technique to measure the concentration of macular carotenoid pigments in the living human retina of young and elderly adults. Using a backscattering geometry and resonant molecular excitation in the visible, we measure the Raman peaks originating from the single- and double-bond stretch vibrations of the (pi) - electron conjugated molecule's carbon backbone. The Raman signals scale linearly with carotenoid content while the required laser excitation is well below safety limits for macular exposure. Measured macular pigment levels decline significantly with increasing age. The Raman technique is objective and quantitative and may lead to a new method for rapid screening of carotenoid pigment levels in large populations at risk for vision loss from age-related macular degeneration, the leading cause of blindness in the elderly in the United States.
We have used resonance Raman scattering as a novel non- invasive optical technology to measure carotenoid antioxidants in human skin of healthy volunteers. Using blue-green laser excitation, clearly distinguishable carotenoid Raman spectra are obtained which are superimposed on a large skin autofluorescence background. The Raman spectra are obtained rapidly, i.e. within about 30 seconds, and the required laser light exposure levels are well within safety standards. Our technique can be used for rapid screening of carotenoid antioxidant levels in large populations and may have applications for assessing the risk for cutaneous diseases.
We have used resonance Raman scattering as a novel, non- invasive, in-vivo optical technique to measure the concentration of carotenoid pigment in the human retina. Using argon laser excitation we are able to measure two strong carotenoid resonance Raman signals at 1159 and 1525 wave numbers, respectively. The required laser power levels are within the limits given by safety standards for ocular exposure. Of the approximately ten carotenoid pigment found in normal human serum, the species lutein and zeaxanthin are concentrated in high amounts in the cells of the human macula, which is an approximately 5 mm diameter area of the retina in which the visual acuity is highest. These carotenoids give the macula a characteristic yellow coloration, and it is speculated that these molecules function as filter to attenuate photochemical damage and/or image degradation under bright UV/blue light exposures. In addition, they are thought to act as free-radical scavenging antioxidants. Studies have shown that there may be a link between macular degenerative diseases, the leading cause of blindness in the elderly in the US, and the presence or absence of the carotenoids. We describe an instrument capable of measuring the macular carotenoids in human subjects in a non-invasive, rapid and quantitative way.
The peculiarities of energy levels structure of laser-active F3+ color centers in LiF crystals were studied. The dependencies of polarization and fluorescence intensity of LiF crystals with F3+ centers against polarization of powerful laser irradiation which originates two-photon excitation of F3+ centers, were measured and calculated. It was shown that the two-photon transition leads to the excitation of unknown previously spin-singlet electronic state, possessing 1A1 wavefunction symmetry.
New spin-triplet electronic states of laser-active F3+ color centers in LiF crystals are discovered. The triplet-triplet absorption spectra from low laying 3E state to the high laying states, triplet-triplet 3T(alpha ) yields 3E fluorescence spectrum and 3E yields 1A1 triplet-singlet phosphorescence spectrum are measured. Temperature dependencies of nonradiative singlet-triplet 1E yields 3E and triplet- singlet 3E yields 1A1 transitions probability are found. The influence of spin-triplet states on the LiF:F3+ color center laser characteristics is discussed. The new way of obtaining of tunable oscillation in wide visible range using triplet-triplet transition is offered.
Barium nitrate Raman laser pumped with nanosecond YAG:Nd laser is investigated. High energy conversion efficiencies to the first, second, and third Stokes components up to 60%, 35%, and 25%, respectively, are obtained. Results on development of Raman laser for the eye safe spectral region are presented.
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