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Purpose: evaluation of the efficiency of the “hot spot” method for the fragmentation of urinary stones. Materials and methods: A retrospective analysis of clinical records of 1666 patients with urolithiasis who underwent percutaneous nephrolithoextraction/tripsy and contact ureterolithotripsy/extraction in the period from 2014 to 2017 at the urology clinic was performed to assess the incidence of postoperative infectious and inflammatory complications. The research objects were postoperative urinary stones (n-78). The X-ray density and linear dimensions of the stones were determined. Stone fragmentation was performed with a continuous-wave diode laser operating at wavelengths of 0.81 μm, 0.97 μm, and 1.47 μm. An absorbing coating of micro-size graphite powder was applied on the working tip of the optical fiber. In vitro fragmentation was carried out in liquid. Results: A group of patients (224/1666) (13.4 ± 0.86%) was identified, who developed infectious and inflammatory complications after: percutaneous nephrolithotripsy, 123/361 (34.1 ± 2.5%) cases; percutaneous nephrolithoextraction, 59/240 (24.6 ± 2.78%); contact ureterolithotripsy, 23/294 (7.8 ± 1.57%); and ureterolithoextraction, 19/771 (2.5 ± 0.56%). In liquid, the “hot spot” technique made it possible to fragment stones with an X-ray density of up to 1000 HU at a laser wavelength of 0.81 µm, up to 1400 HU at 0.97 µm, and up to 1400 HU at 1.47 µm.

Genetically encoded photosensitizers are a unique instrument for investigation of cellular mechanisms of photodynamic therapy (PDT). Fluorescent flavoprotein miniSOG (mini Singlet Oxygen Generator) generates singlet oxygen with a high yield and demonstrates strong phototoxic properties in vitro in cancer cells. However, the effective approaches for PDT with miniSOG have not been developed so far. The purpose of the study is to investigate phototoxic effects of miniSOG induced by continuous wave (CW) or pulsed laser irradiation in tumor spheroids. We found that maximum photobleaching of miniSOG without temperature effects was achieved at 120 mW/cm2 in CW mode or pulse periodic mode. PDT in pulse periodic mode provided more pronounced increase in the number of dead cells in comparison with CW mode and, moreover, induced apoptosis more efficiently. Therefore, we report for the first time on an effective regimen for PDT with miniSOG in a tumor spheroid model using pulsed periodic laser irradiation.

Background Therapeutic effects of PDT depend on many factors, including the amount of singlet oxygen, localization of photosensitizer and irradiation protocol. The present study was aimed to compare the cytotoxic mechanisms of PDT under continuous-wave (CW) and pulsed irradiation using a tumor spheroid model and a genetically encoded photosensitizer miniSOG. Methods 1O2 detection in miniSOG and flavin mononucleotide (FMN) solutions was performed. Photobleaching of miniSOG in solution and in HeLa tumor spheroids was analyzed. Tumor spheroid morphology and growth and the cell death mechanisms after PDT in CW and pulsed modes were assessed. Results We found a more rapid 1O2 generation and a higher photobleaching rate in miniSOG solution upon irradiation in pulsed mode compared to CW mode. Photobleaching of miniSOG in tumor spheroids was also higher after irradiation in the pulsed mode. PDT of spheroids in CW mode resulted in a moderate expansion of the necrotic core of tumor spheroids and a slight inhibition of spheroid growth. The pulsed mode was more effective in induction of cell death, including apoptosis, and suppression of spheroid growth. Conclusions Comparison of CW and pulsed irradiation modes in PDT with miniSOG showed more pronounced cytotoxic effects of the pulsed mode. Our results suggest that the pulsed irradiation regimen enables enhanced 1O2 production by photosensitizer and stimulates apoptosis. General significance Our results provide more insights into the cellular mechanisms of anti-cancer PDT and open the way to improvement of light irradiation protocols.

Photodynamic inactivation (PDI) is considered to be an effective method of prevention of postoperative complications of urolithiasis. The present study shows a complex approach to assess the efficacy of PDI of drug resistant bacteria associated with renal calculi. Bacterial strains associated with renal calculi were isolated and identified using standard methods of bacteriological analysis and tested for drug resistance to 10 antibiotics by the disco-diffusion method. Uropathogenic bacterial strains present in 78.7 ± 5.2% of the infected samples from the total number of analyzed calculi. The most frequent representatives belonged to the genera Staphylococcus, Escherichia, and Enterococcus. All tested strains showed high antibiotic resistance. Representatives of the most common bacterial genera in the calculi were used as models for the selection of PD exposure modes. It was found that the maximum time of photosensitizer accumulation depends on the structure of the bacterial cell wall: 30 min for Gram-negative strains and 60 min for Gram-positive ones. Optimal modes of PD exposure to antibiotic-resistant uropathogenic microorganisms were selected: 50 µg/mL Fotoditazin and 150 mW laser power. The maximal bactericidal activity of PDI against uropathogenic microorganisms was shown for Enterococcus faecalis, and Staphylococcus aureus. The bacteriostatic effect was found against Escherichia coli and Proteus mirabilis.

Light–heat converters are promising for further development of contact laser surgery. The simplest converter consists of an optical fiber with a strong absorbing layer at the tip. We studied the time dependence of the tip temperature at different CW laser powers and revealed that, in several seconds, the temperature evolution becomes almost power-independent. Mathematical modeling showed that laser ablation of the tip coating is the main reason for this phenomenon.

The problems of controlling the processes of generation of acoustic waves and microbubbles at the optical fiber tip of moderate-power surgical lasers with wavelengths of 1.9 µm and 0.97 µm using active and passive acoustic methods are considered. It is shown that microbubbles of various sizes can be detected with an ultrasound method, in which the interaction area is recorded simultaneously at two frequencies. By measuring noise with a receiving transducer of an ultrasonic locator, we determine the frequency range of the acoustic signals occurring when large diameter bubbles, including gas-vapor bubbles, collapse. Model experiments are conducted to detect noise and bubbles in water and in a water-saturated 1.5% agarose phantom at various laser powers with an optical fiber tip having a strongly absorbing coating.

The bactericidal effect of laser radiation with a quartz fiber-based transmission system with a strong absorption coating converter against bacteria associated with urological stones has been studied. Gram-negative rod Escherichia coli and the Gram-positive coccus Staphylococcus epidermidis, Staphylococcus aureus, Enterococcus faecalis and Enterococcus faecium were used in this study. Each bacterial species was treated by continuous-wave near infrared laser coupled with bare fiber tip or strongly absorption coating fiber tip. After treatment, the temperature of bacterial suspension was measured. In addition, the temperature distribution was analyzed. It has been shown that using laser with a strongly absorption coating fiber tip results in significant bactericidal effect. The decrease of the amount of E. coli and S. epidermidis was 100% after treatment with an output power of 6[Formula: see text]W of radiation at a wavelength of 0.97[Formula: see text][Formula: see text]m for 40[Formula: see text]s. Number of S. aureus and Ent. faecium colony-forming unit was reduced to 70% after same exposure. The peak temperature of bacterial suspension was [Formula: see text]C after treatment by laser with a strongly absorption coating fiber tip. Laser with a strongly absorption coating fiber tip provides large-scale hydrodynamic flows directed away from the fiber tip. The laser with a strongly absorption coating fiber tip has bactericidal effect. The main role is associated with the effect of high temperature, which, in the form of flow in a liquid medium, affects bacteria.

KillerRed is known to be a unique red fluorescent protein displaying strong phototoxic properties. Its effectiveness has been shown previously for killing bacterial and cancer cells in vitro. Here, we investigated the photototoxicity of the protein on tumor xenografts in mice. HeLa Kyoto cell line stably expressing KillerRed in mitochondria and in fusion with histone H2B was used. Irradiation of the tumors with 593 nm laser led to photobleaching of KillerRed indicating photosensitization reaction and caused significant destruction of the cells and activation of apoptosis. The portion of the dystrophically changed cells increased from 9.9% to 63.7%, and the cells with apoptosis hallmarks from 6.3% to 14%. The results of this study suggest KillerRed as a potential genetically encoded photosensitizer for photodynamic therapy of cancer. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Collagen modifications in the tissues of an annulus fibrosus under moderate-intensity IR laser irradiation at various pulse durations and frequencies were studied. Changes at various levels of the ordered structural hierarchy of collagen in tissues were detected by differential scanning calorimetry, multiphoton microscopy with second harmonic generation, and cross-polarized optical coherence tomography. The obtained data confirm the photothermal and photomechanical effect of IR laser action on fibrous structures. Details of these effects (mechanical defect formation or protein denaturation) were determined, and the greatest tissue damage was demonstrated to be generated by their combined action.

The potentialities of diffuse optical spectroscopy for the noninvasive estimation of the oxygen state of experimental tumors have been demonstrated. The distribution of total, oxygenated and deoxygenated hemoglobin, as well as the level oxygen saturation of blood have been shown using two tumor models differing in the histological structure and functional characteristics. The results obtained by the optical method have been verified by immunohistochemical examination of tissue specimens with the exogenous hypoxia marker pimonidazole.

New type of optoacoustic transducer containing monolayer of dielectric spheres is presented. Experiments of the ultrasound generation by the single nanosecond laser pulses (2nd harmonic of Nd:YAG) in a liquid absorbing ink were carried out. It was found that the irradiation of the liquid through a mask containing the monolayer of glass spheres result in the greater ultrasound intensity and the broader spectrum compared to the same setup without the mask. The effect is explained by the focusing of the laser light by the spheres. The laser intensity is being concentrated into the multitude of the 'hot spots' where the high-frequency ultrasound is generated.

A modification of the polarization reflection spectroscopy method is proposed with the use of a polarization-maintaining single-mode fiber. The choice of the fiber made it possible to create an optimal self-consistent system for the illumination of a biological tissue and the reception of scattered radiation and to create a probe compatible with any endoscopic equipment. The first clinical results of diagnosing tumor diseases with the created instrument showed that it is possible to determine the tumor-norm boundary, which is very important for organ-preserving operations. All of the results obtained by this method agree well with the results obtained by the method of polarization-sensitive optical coherence tomography.

The capabilities of diffuse optical spectroscopy for noninvasive assessing of oxygen status in experimental tumors have been demonstrated. Specific features of the distribution of total hemoglobin, oxygenated hemoglobin, deoxygenated hemoglobin, and blood-oxygen saturation were shown on two tumor models having different histological structure and functional characteristics. The results obtained by the optical technique were verified by immunohistochemical study of tissue samples marked with exogenous marker of hypoxia – pimonidazole. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

In this study, dynamics of nanoparticles penetrating and accumulating in biotissue (healthy skin) was investigated in vivo by the noninvasive method of optical coherence tomography (OCT). Gold nanoshells and titanium dioxide nanoparticles were studied. The processes of the nanoparticles penetration and accumulation in biotissue are accompanied by the changes in optical properties of skin which affect the OCT images. The continuous OCT monitoring of the process of the nanoparticles penetration into skin showed that these changes appeared in 30 min after application of nanoparticles on the surface; the time of accumulation of maximal nanoparticles concentration in skin was observed in period of 1.5–3 h after application. Numerical processing of the OCT signal exhibited the increase in contrast between upper and lower parts of dermis and contrast decay of the hair follicle border during 60–150 min. The transmission electron microscopy technique confirmed accumulation of the both types of nanoparticles in biotissue. The novelty of this study is presentation of OCT ability to in vivo monitor dynamics of nanoparticles penetration and their re-distribution within living tissues.

We make comparative studies of structural changes of in vitro biotissues subject to the infrared (IR) laser radiation and the radio-frequency field. Noninvasive diagnostics and monitoring of microstructural changes of biological tissues are performed using optical coherent tomography.

The efficiency of the mechanical compression of biotissues for improving the differentiation between pathological changes in the structure of a biotissue observed by the method of optical coherence tomography (OCT) is investigated. The effect of the compression in the OCT-images of samples of the human rectum affected by inflammation and carcinoma is studied ex vivo. It is shown that the use of compression makes it possible to differentiate between these pathological changes. To interpret experimental data, images of an inflamed part of rectum are modeled by the Monte Carlo method for different degrees of compression. The results of modeling agree qualitatively with the experimental data.

The possibility of using silica-gold nanoshells with 150 nm silica core size and 25 nm thick gold shell as contrasting agents for optical coherence tomography (OCT) is analyzed. Experiments on agar biotissue phantoms showed that the penetration of nanoshells into the phantoms increases the intensity of the optical coherence tomography (OCT) signal and the brightness of the corresponding areas of the OCT image. In vivo experiments on rabbit skin demonstrated that the application of nanoshells onto the skin provides significant contrasting of the borders between the areas containing nanoshells and those without. This effect of nanoshells on skin in vivo is manifested by the increase in intensity of the OCT signal in superficial parts of the skin, boundary contrast between superficial and deep dermis and contrast of hair follicles and glands. The presence of nanoshells in the skin was confirmed by electron microscopy. Monte Carlo simulations of OCT images confirmed the possibility of contrasting skin-layer borders and structures by the application of gold nanoshells. The Monte Carlo simulations were performed for two skin models and exhibit effects of nanoparticles similar to those obtained in the experimental part of the study, thus proving that the effects originate exactly from the presence of nanoparticles.

An experimental setup for multicolor frequency-domain diffuse optical tomography (FD DOT) was created to visualize neoplasia of breast tissue and to estimate its size. The breast is gently pressed between two glass plates and scanned in the transilluminative configuration by a single source and detector pair. Illumination at three wavelengths (684 nm, 794 nm, and 850 nm) which correspond to different parts of the absorption spectrum in a therapeutic transparency window provides information about concentration of the main absorbers (oxygenated hemoglobin, deoxygenated hemoglobin, and fat/water). Source amplitude modulation at 140 MHz increases spatial resolution and provides separate reconstruction of scattering and absorption coefficients. Moreover, it gives information about breast thickness, which is important for reconstruction. The sensitivity of the system enables one to detect the light propagated through tissue having thickness up to 8 cm. Studies on model media and preliminaryin vivoexperiments with normal breast and breast carcinoma were performed. An increase of scattering coefficient and total hemoglobin concentration is observed in the tumor area. This corroborates validity of the FD DOT method for breast cancer diagnosis.

UV irradiation of materials consisting of a polymer matrix that possesses precursors of different kinds can result in creation of nanoparticles within the irradiated domains. Such photoinduced nanocomposites are promising for photonic applications due to the strong alteration of their optical properties compared to initial non-irradiated materials. We report our results on the synthesis and investigation of plasmonic, excitonic and exciton-plasmonic photoinduced nanocomposites. Plasmonic nanocomposites contain metal nanoparticles of noble metals with a pronounced plasmon resonance. Excitonic nanocomposites possess semiconductor nanoclusters (quantum dots). We consider the CdS–Au pair because the luminescent band of CdS nanoparticles enters the plasmon resonance band of gold nanoparticles. The obtaining of such particles within the same composite materials is promising for the creation of media with exciton–plasmon resonance. We demonstrate that it is possible to choose appropriate precursor species to obtain the initially transparent poly(methyl methacrylate) (PMMA) films containing both types of these molecules either separately or together. Proper irradiation of these materials by a light-emitting diode operating at the wavelength of 365 nm provides material alteration demonstrating light-induced optical absorption and photoluminescent properties typical for the corresponding nanoparticles. Thus, an exciton-plasmonic photoinduced nanocomposite is obtained. It is important that here we use the precursors that are different from those usually employed.

In the present communication, it is shown that a laser scalpel operating at the wavelength of 0.97 μm with a fiber tip having a strongly absorbing coating proves to be efficient for making contact incisions. At 6 W laser pump radiation, the temperature of silica glass on the cutting fiber tip during cutting is close to the silica glass softening point. The high fiber tip temperature allows bloodless resection with the cut depth of more than 1 mm and with high tissue cutting speed.

The purpose of this study was to characterize essential changes in the structure of annulus fibrosus (AF) after hydrothermal and infrared (IR) laser treatment and to correlate these results with alterations in tissue state. Polarization-sensitive optical coherence tomography imaging was used to measure collagen birefringence in AF. Differential scanning calorimetry was used as a complementary technique, providing detailed information on thermodynamic processes in the tissue. Birefringence, peak of the denaturation endotherm, and the enthalpy of denaturation (DeltaHm) were determined before and after hydrothermal heat treatment (85 degrees C for 15 min) and non-ablative Er:glass fiber laser exposures on AF in the whole disk (vertebrae-disk-vertebrae complex). Our data have demonstrated quantitative differences between results of laser and hydrothermal heating. Birefringence did not disappear and DeltaHm did not change after treatment in the water bath, but loss of birefringence and a decrease in the enthalpy did occur after laser exposure. These results could be explained by the photomechanical effect of laser irradiation. We suggest that thermo-mechanical stress played a dominant role in the disruption of the collagen network of AF under non-homogeneous laser heating.

The strong phototoxicity of the red fluorescent protein KillerRed allows it to be considered as a potential genetically encoded photosensitizer for the photodynamic therapy (PDT) of cancer. The advantages of KillerRed over chemical photosensitizers are its expression in tumor cells transduced with the appropriate gene and direct killing of cells through precise damage to any desired cell compartment. The ability of KillerRed to affect cell division and to induce cell death has already been demonstrated in cancer cell lines in vitro and HeLa tumor xenografts in vivo. However, the further development of this approach for PDT requires optimization of the method of treatment. In this study we tested the continuous wave (593 nm) and pulsed laser (584 nm, 10 Hz, 18 ns) modes to achieve an antitumor effect. The research was implemented on CT26 subcutaneous mouse tumors expressing KillerRed in fusion with histone H2B. The results showed that the pulsed mode provided a higher rate of photobleaching of KillerRed without any temperature increase on the tumor surface. PDT with the continuous wave laser was ineffective against CT26 tumors in mice, whereas the pulsed laser induced pronounced histopathological changes and inhibition of tumor growth. Therefore, we selected an effective regimen for PDT when using the genetically encoded photosensitizer KillerRed and pulsed laser irradiation.

Quantum dots (QD) are a new class of fluorescence labels with properties and biomedical applications that are not available with traditional organic dyes and fluorescent proteins. The unique optical properties of QDs (high absorption, quantum yield and emission spanning to near IR) make them attractive asin vivomarkers for deep-tissue imaging. Different types of optical tomography allow imaging of fluorescent-labeled tumors located deep in human or animal tissue. In this work, preliminary results of the fluorescent diffuse tomography (FDT) method in application to CdTe/CdSe-core/shell fluorescing nanocrystals are reported. In our experiments we utilized low-frequency amplitude modulation (1 kHz) of the second harmonic of Nd:YAG laser (532 nm). The transilluminative configuration was used in the setup. Results of post mortem experiments with capsules containing QDs placed into esophagus of small animals to simulate labeled tumor are shown. An algorithm of processing fluorescent image based on calculating zero of maximum curvature has been applied to detect fluorescent inclusions boundaries on the image. This work demonstrates potential capabilities of the FDT method for imaging of deep fluorescent tumors in human tissue or animal models of human cancer.

Ensuring the complete removal of tumor tissue is the main challenge during resection operations. Recently, a technique of “indirect” contact laser surgery has been developed. In this study we assess the possibility of using such surgery for fluorescence image-guided tumor resection. Mouse colon adenocarcinoma CT-26 cells stably expressing the fluorescent protein mKate-2 was used as the tumor model. Resections of the tumor nodes were performed with either a scalpel blade, a laser scalpel with a bare tip, or a laser scalpel with a strongly absorbing coating on the fiber tip. Tumor-positive resection margins were detected using an IVIS Spectrum fluorescence imaging system. After tumor resection with the scalpel blade over half of the animals needed one additional resection to remove residual tumor cells. Animals in this group showed tumor recurrence within 7 days. Fluorescence imaging of the tumor bed, performed after resection to assess the presence of tumor cell clusters, was sufficiently effective only with a bloodless resection. The laser scalpels both with the bare tip and with the strongly absorbing coating on the tip provided such bloodless tumor resection in contact mode. Fewer animals required additional resections when the bare tipped scalpel was used and this also resulted in a reduction in tumor recurrence. After resections were carried out with the laser scalpel with the strongly absorbing coating on the tip, fluorescence was detected in the operative field and this led to undertaking additional resections, although subsequent investigation suggested that this was “false” fluorescence, resulting from the effects of the scalpel rather than the presence of residual tumor cells. The method of laser resection with a strongly absorbing coating on the tip therefore did not appear to demonstrate definite advantages over laser resection with a bare tip when removing tumors.

Background/purpose The goal of the study is comparative analysis of the layers in OCT images and the morphological structure of skin with thick and thin epidermis. Methods We analyzed the difference between skin with thin and thick epidermis in two ways. The first approach consisted in determination of the thicknesses of layers of skin with thin and thick epidermis of different localizations from experimental OCT images. The second approach was to develop numerical models fitting experimental OCT images based on Monte Carlo simulations revealing structure and optical parameters of layers of skin with thick and thin epidermis. Results The correspondence between the OCT images of skin with thin and thick epidermis and the morphological structure was confirmed. OCT images of healthy skin comprise three layers in case of skin with thin epidermis and four layers in skin with thick epidermis. The OCT image of the zone of the transition from skin with thick to skin with thin epidermis features five layers. Conclusion The revealed differences in the structure of horny and cellular layers of epidermis, as well as of papillary and reticular dermis in skin with thin and thick epidermis specify different optical properties of these layers in OCT images.

The purpose of this study was to evaluate photobleaching of the genetically encoded photosensitizer KillerRed in tumor spheroids upon pulsed and continuous wave (CW) laser irradiation and to analyze the mechanisms of cancer cell death after the treatment. We observed the light-dose dependent mechanism of KillerRed photobleaching over a wide range of fluence rates. Loss of fluorescence was limited to 80% at light doses of 150 J/cm(2) and more. Based on the bleaching curves, six PDT regimes were applied for irradiation using CW and pulsed regimes at a power density of 160 mW/cm(2) and light doses of 140 J/cm(2) , 170 J/cm(2) and 200 J/cm(2). Irradiation of KillerRed-expressing spheroids in the pulsed mode (pulse duration 15 ns, pulse repetition rate 10 Hz) induced predominantly apoptotic cell death, while in the case of CW mode the cancer cells underwent necrosis. In general, these results improve our understanding of photobleaching mechanisms in GFP-like proteins and show the importance of appropriate selection of treatment mode for PDT with KillerRed. Representative fluorescence image of two KillerRed-expressing spheroids before and immediately after CW irradiation.

Purpose: To evaluate the dose-time dependences of structural changes occurring in collagen within 24 hours to three months after gamma-irradiation at doses from 2–40 Gy in vivo. Materials and methods: Rat’s tail tendon was chosen as in vivo model, with its highly ordered collagen structure allowing the changes to be interpreted unambiguously. Macromolecular level (I) was investigated by differential scanning calorimetry (DSC); fibers and bundles level (II) by laser scanning microscopy (LSM), and bulk tissue microstructural level (III) by cross-polarization optical coherence tomography (CP-OCT). Results: For (I), the formation of molecular cross-links and breaks appeared to be a principal mechanism of collagen remodeling, with the cross-links number dependent on radiation dose. Changes on level (II) involved primary, secondary and tertiary bundles splitting in a day and a week after irradiation. Bulk collagen microstructure (III) demonstrated early widening of the interference fringes on CP-OCT images observed to occur in the tendon as result of this splitting. At all three levels, the observed collagen changes demonstrated complete remodeling within ∼ a month following irradiation. Conclusion: The time course and dose dependencies of the observed collagen changes at different levels of its hierarchy further contribute to elucidating the role of connective tissue in the radiotherapy process.

Radiotherapy (one of the main cancer treatment modalities) is also associated with side effects in disease-free tissues. One of the crucial mechanisms of late radiation complications is the synthesis of the excessive amount of collagen that leads to radiation induced fibrosis. Laser scanning microscopy with second harmonic generation allows revealing collagen changes without additional staining. The work objective was to study if laser scanning microscopy may give additional information about radiation induced collagen changes in normal tissues (bladder and rectum).

Background and Objective The goal of this study is to apply a new bioimaging modality, the Optical Coherence Tomography (OCT), for intraoperative control in laser surgery of laryngeal carcinoma. Study Design/Materials and Methods We studied 26 patients with laryngeal carcinoma in situ and in T1, T2 stage. We used an endoscopic OCT device for imaging at a wavelength of 0.83 μm with the acquisition rate of approximately 0.5 frames/s for a single (200 × 200 pixel) tomogram. All patients were operated with a surgical YAG:Nd laser at two switchable wavelengths of 1.44 μm and 1.32 μm by laryngofissure, direct microlaryngoscopy, and fibrolaryngoscopy. Results Information on structural alterations in laryngeal mucosa to the depth of 2 mm, obtained by OCT, makes it possible to precisely locate tumor borders, thus giving an opportunity to control the surgical treatment of laryngeal carcinoma. The YAG:Nd laser scalpel with wavelengths of 1.32 μm and 1.44 μm is successful in surgical procedures both in open and closed larynx due to efficient coagulation and minimization of collateral tissue damage area. Combination of the two wavelengths in the single laser unit and intraoperative OCT monitoring result is a new modality for minimally invasive larynx surgery. Conclusions OCT is promising to become a new diagnosing method of laryngeal carcinoma and a tool for laser treatment monitoring. J. Surg. Oncol. 2001;77:253–258. © 2001 Wiley-Liss, Inc.

Adverse events in normal tissues after irradiation of malignant tumors are of great importance in modern radiation oncology. Second harmonic generation (SHG) microscopy allows observe the structure of collagen fibers and bundles without additional staining. The study objective was evaluation the dose-time dependences of the structural changes occurring in collagen of rat rectum and bladder after gamma-irradiation. Animals were irradiated by a local field at single doses of 10 Gy and 40 Gy. The study of collagen state was carried out in a week and a month after radiation exposure. Paraffin-embedded material was sectioned on the slices 10 mkm thick and SHG-imaging was performed by LSM 510 Meta (Carl Zeiss, Germany). Excitation was implemented with a pulsed (100-fs) titanium-sapphire laser at a wavelength of 800 nm and a pulse repetition frequency of 80 MHz, registration was performed at two wavelengths: 362-415 nm according to collagen fluorescence and 512-576 nm according to myoglobin fluorescence. In a week after irradiation, sings of epithelial damage and edema of submucosal layer, more significant after the dose of 40 Gy were observed on LSM-images. The SHG signal decreased at this time reflecting the processes of collagen degradation independently either in bladder or in rectum. In a month after radiation the increase of size and number of collagen-bearing structures was observed, more essential after irradiation in a dose of 40 Gy. LSM microscopy with SHG allows evaluate changes of normal tissues after ionizing radiation and get information in addition to standard and special histological staining.

Optical coherence tomography (OCT) is rapidly advancing into clinical practice beyond the area of ophthalmology. Many applications of OCT in areas such as dermatology, endoscopy and others require contact OCT probes which transfer compression to the studied tissues. This effect should be taken into account when developing methods for OCT diagnostics. On the other hand, controlled compression can provide additional diagnostic information and can serve as a diagnostic procedure. This paper discusses the effect of controlled mechanical compression induced by an OCT probe coupled with dynamometer on cross-polarization OCT images of skin. Registration of OCT images in two polarizations (parallel and orthogonal) allows additional information to be obtained about structural features of the studied tissue. An increase in contrast of epidermis/dermis junction and a decrease in contrast of stratum corneum/epidermis junction in OCT images are shown to originate from mechanical compression of human skin

Nizhny Novgorod Research Institute of Traumatology and Orthopedics,Nizhny Novgorod, RussiaBackground/purpose: The present study aimed to investigatethe influence of topical corticosteroid therapy and tacrolimuson morphological indices of different skin phototypes and tooptimize topical therapy using the OCT technique.Methods: Twenty healthy volunteers aging from 20 to 30 (14men and 6 women) took part in the study: 10 persons with skinphototype I, II and 10 persons with skin phototype V, VI. Mor-phological state of the skin was assessed before and duringapplication of topical steroids of different strength and calcium-neurin inhibitors for 49 days. Morphological state was studiedin vivo using the optical coherence tomograph.Results: Morphological manifestations of skin atrophy withthe use of clobetasol propionate appear earlier than with theuse of hydrocortisone 17-butyrate; this process was faster inrepresentatives of groups V, VI. Epidermal thinning in thezone of tacrolimus application was not recorded in anyphototype.Conclusion: Recording of early preclinical signs of epidermisthinning in the course of OCT follow-up may be an indicationfor changing the corticosteroid therapy by calciumneurin inhibi-tors, which will permit to individualize the therapy, to increaseits efficacy, and to minimize the possibility of complications ineach particular case.Key words: optical coherence tomography – skin atrophy –skin phototypes – tacrolimus – topical corticosteroids

We present a theoretical model for laser cutting of biological tissue by a strongly heated fiber tip with a highly absorbing coating. A significant dependence of the cutting speed and cutting depth on the inclination angle of the scalpel to the surface when scattering exceeds absorption in the biological tissue is shown. Experimental evidences of this effect are presented. In the experiment, we used silica fiber with coating made of carbon and silicon organic varnish, the 0.97-µm wavelength laser and porcine skin. The additional opportunity to increase the efficiency of cutting by deposition of the absorbing layer on the tissue surface is considered.

In this paper, we consider a method of laser resection using the silica glass core from which the cladding layer has been removed as the cutting part of a laser scalpel. An absorbing layer coating the silica fiber tip markedly alters its biotissue cutting characteristics. The results of histological studies of skin after exposure to a laser scalpel with and without a strongly absorbing coating (SAC) at a wavelength of 0.97[Formula: see text][Formula: see text]m show that resection using a coated scalpel is more sparing. When an uncoated scalpel was used, skin injury was more apparent in both its surface spread and the depth of structural damage, resulting in poorer tissue regeneration.

We demonstrate the possibility of detection and monitoring of bubbles emerging near the tip of an optical fiber by means of ultrasonic method. The excitation of bubbles at their resonant frequencies is performed using short ultrasonic pulses having a wide frequency range simultaneously with their modulation by means of a long pulse of a monochromatic frequency. This method allows detection of bubbles of various sizes. Used signal processing method, which allows increased bubble detection accuracy, is proposed for research in environments of biological-like medium which show continuous variations in structure and properties when exposed to optical emission. The method has been demonstrated on model objects: in a liquid and in a biological tissue phantom using various methods of bubble generation (hydrolysis and optical emission). We studied bubble formation by the tip of a fiber of the surgical laser LSP-007/10 “IRE Polus” with a wavelength of 0.97[Formula: see text][Formula: see text]m coated with a highly absorbing graphite layer.

We demonstrate that optical coherence tomography (OCT) is a convenient diagnostic tool to monitor pulse-to-pulse kinetics in laser interactions with biological tissue. In experiments on laser modification and ablation of the cataractous human lens and the porcine cornea we have applied this technique in situ to investigate different modes of preablation tissue swelling, crater formation and thermally affected zone development. The cataractous lens is an example of highly scattering media whereas the cornea is initially low scattering. The radiation with different wavelengths has been employed including that of a YAG:Er laser (λ=2.94 μm), a glass:Er laser (λ=1.54 μm), YAG:Nd lasers (λ=1.32 μm and λ=1.44 μm), as well as of the fifth harmonic of a Nd:YAP laser (λ=0.216 μm). Pulse-to-pulse OCT monitoring has been accompanied by the probe beam shielding diagnostics to provide the time-resolved observation of the interaction dynamics. © 1999 Society of Photo-Optical Instrumentation Engineers.

Objective The goal of the described study was complex assessment of age-specific morphofunctional features of skin of different anatomic localization using optical coherence tomography (OCT). Methods Forty-three healthy volunteers aging from 4 to 74 years were enrolled in the study. Optical and functional skin parameters were studied in 18 areas of the human body. All the studied areas were classified as open and closed, depending on external impact. Structural parameters of skin were determined by means of the OCT device equipped with a removable, flexible probe with microscanner (registration certificate no. 022a2035/2213-05) designed and fabricated at the IAP RAS (Nizhny Novgorod, Russia) with longitudinal and transverse resolution of about 20 μm. Results Age-specific morphofunctional features of skin most evident in areas exposed to external action were found. Statistically significant difference in elasticity (−0.57, P = 0.00012) in areas closed to external action (further referred to as closed areas) and in useful signal depth, hydration and elasticity in areas exposed to external action (further referred to as open areas) was assessed for different age groups. Analysis of the dependence of parameters on age showed statistically significant correlations between age and thickness of cellular layers of the epidermis (−0.33, P = 0.035), pigmentation level (−0.22, P = 0.044) and elasticity in closed areas and highly significant correlations between age and hydration and elasticity in open areas. Conclusion The current work is concerned with investigation of age-specific morpho-functional parameters of skin of different localizations.

Contrasting of biotissue layers in OCT images after application of mechanical compression is discussed. The study is performed on ex vivo samples of human rectum, and in vivo on skin of human volunteers. We show that mechanical compression provides contrasting of biotissue layer boundaries due to different mechanical properties of layers. We show that alteration of pressure from 0 up to 0.45 N/mm2 causes contrast increase from 1 to 10 dB in OCT imaging of human rectum ex vivo. Results of ex vivo studies are in good agreement with Monte Carlo simulations. Application of pressure of 0.45 N/mm2 causes increase in contrast of epidermis-dermis junction in OCT-images of human skin in vivo for about 10 dB.

Modern optical diagnostic techniques often require deformations of the studied biotissues for image acquisition. This paper discusses the effect of mechanical compression on the formation of OCT images of human skin. The study was performed in vivo on human volunteers of different age. We show that application of compression to human skin induces changes in optical properties of the sample associated with elasticity of different skin layers. These changes induce an increase in the contrast of interlayer boundaries. Further application of compression causes the appearance of dark areas in the OCT images obtained, likely associated with interstitial or intracellular water inflow to the observed region. The effects studied are of importance for proper interpretation of obtained OCT images in diagnosis of skin pathologies. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The goal of this study is the development of a method of local laser hyperthermia with gold nanoparticles under noninvasive optical monitoring of nanoparticle accumulation in tumor tissue in vivo. Bifunctional plasmon resonant nanoparticles that are optimal for OCT diagnostics and laser heating at the wavelength of 810 nm were used in the study. The OCT examination showed that the accumulation of gold nanoparticles in the tumor invading into skin was maximal 4–5 h after intravenous injection. It was demonstrated that nanoparticle accumulation in tumor allowed more local heating and enhanced thermal sensitivity of tumor tissue. Laser hyperthermia that heated tumor up to 44–45 °C at maximum nanoparticle accumulation induced apoptotic death of tumor cells and inhibited tumor growth by 104% on the 5th day after treatment. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

In the current paper we present preliminary data demonstrating therapeutic efficiency of local laser hyperthermia of mouse tumors with gold nanoparticles. Measuring the tumor temperatures both superficial and inner by means of standard NIR-thermograph and original acoustic thermometer correspondingly we show that the gold nanoparticles increase thermal sensitivity of tumor tissue. Transmission electron microscopy and histopathology of the tumor tissue indicated that the mechanism of apoptotic death of tumor cells is triggered following the laser treatment. 5 days after the treatment tumor growth inhibition was 104 %.

The study was performed on 16 CBA-line female mice with transplanted cervical cancer. 0.2 ml of gold nanoparticle solution with a concentration of 10 9 particles/ml were injected into the animals intravenously. The particles were 200-250 nm in size; the plasmon-resonance related extinction maximum was at the wavelength of 850-950 nm. Accumulation of the nanoparticles into tumor node was visualized by the method of optical coherence tomography (OCT). When the accumulation of nanoparticles in the tumor was maximal, hyperthermia was accomplished using the LSP-AZOR laser setup generating cw radiation at 810 nm. The duration of exposition was 20 min. The therapeutical effect was assessed by the rate of tumor growth inhibition (TGI, %). Determining the instant when nanoparticle concentration in tumor tissue reaches its maximum enables more efficient laser impact. The use of nanoparticles decreases laser irradiation power and ensures local action.

The paper discusses application of mechanical compression for contrasting structural components of biotissues with different mechanical properties in optical coherence tomography (OCT) images. Ex vivo study on human rectum samples and in vivo study on human thin skin samples are performed. It is shown that for ex vivo sample the contrast between epithelial and stroma layers increases with increase in applied pressure. For in vivo sample it is shown that at weak constant applied pressure the contrast between epidermal and dermal layer increases exhibiting maximum after 2-3 minutes since pressure application. Monte Carlo simulations of OCT images of human rectum sample at different compression levels is performed in order to confirm the origin of contrast. The results of simulations qualitatively agree with experimental data.

An experimental standard optical coherence tomography (OCT) setup that can be easily modified for cross-polarization OCT (CP OCT) operation has been developed to perform differential diagnosis of pathological tissues. The complementary use of CP OCT, a technique that provides a map of cross-polarization backscattering properties of an object being studied by means of low-coherence interferometry, and standard OCT imaging improves the specificity of diagnostics of pathological changes occurring in tissues. It is shown that healthy, neoplastic and scar tissues of the esophagus have different cross-polarization backscattering properties. A comparative analysis of CP OCT, OCT and histological images from one and the same tissue area has been made. A close correlation between the location of collagen fibers in biological tissue and signal intensity in CP OCT images is found.

Diffuse Optical Tomography (DOT) is based on acquiring information from multiply scattered light which penetrates into the tissue up to depths of several centimeters. This technique allows for imaging of absorbing and scattering inclusions inside tissue and distinguishing between them after computer processing of an image. An experimental setup for multicolor frequency-domain diffuse optical tomography (FD DOT) to visualize neoplasia of breast tissue and to estimate its size has been created. A breast is scanned in the transilluminative configuration by a single source and detector pair. Illumination at three wavelengths (684 nm, 794 nm, and 850 nm) which correspond to different parts of the absorption spectrum provides information about concentration of the main absorbers (oxygenated hemoglobin, deoxygenated hemoglobin, and fat/water). Source amplitude modulation at 140 MHz increases spatial resolution and provides separate reconstruction of scattering and absorption coefficients. In vivo study of breast carcinoma has been performed. Maps of 2D distributions of reconstructed absorption and scattering coefficients and concentration of hemoglobin have been obtained. An increase of absorption and scattering coefficient, total hemoglobin concentration and decrease of blood oxygen saturation is observed in the tumor area in comparison with the surrounding tissue. We can conclude that FD DOT technique confirms a possibility of detecting neoplastic changes.

A fluorescence diffuse tomography (FDT) setup for monitoring tumor growth in small animals has been created. In this setup an animal is scanned in the transilluminative configuration by a single source and detector pair. To remove stray light in the detection system, we used a combination of interferometric and absorption filters. To reduce the scanning time, an experimental animal was scanned using the following algorithm: (1) large-step scanning to obtain a general view of the animal (source and detector move synchronously); (2) selection of the fluorescing region; and (3) small-step scanning of the selected region and different relative shifts between the source and detector to obtain sufficient information for 3D reconstruction. We created a reconstruction algorithm based on the Holder norm to estimate the fluorophore distribution. This algorithm converges to the solution with a minimum number of fluorescing zones. The use of tumor cell lines transfected with fluorescent proteins allowed us to conduct intravital monitoring studies. Cell lines of human melanomas Mel-P, Mel-Ibr, Mel-Kor, and human embryonic kidney HEK293 Phoenix were transfected with DsRed-Express and Turbo-RFP genes. The emission of red fluorescent proteins (RFPs) in the long-wave optical range permits detection of deep-seated tumors. In vivo experiments were conducted immediately after subcutaneous injection of fluorescing cells into small animals.