Controlled Fragmentation of Urinary Stones as a Method of Preventing Inflammatory Infections in the Treatment of Urolithiasis (Experience in Successful Clinical Use).

The introduction of technologically advanced methods of lithotripsy into medical practice changes the nature of postoperative complications. Among them, the main complications are inflammatory infections. This largely determines the search for new, improved methods of stone fragmentation avoiding small stone fragments and dissemination of the pelvicalyceal system of the kidney with stone-associated infection. The authors have developed a method for controlled stone fragmentation using a continuous-wave diode laser with a hot-spot effect at the optical fiber end. The aim of the study was to evaluate the efficacy of controlled urinary stone fragmentation using a continuous-wave diode laser with a highly heated distal end of the optical fiber light guide as a method of preventing inflammatory infections in clinical practice. MATERIALS AND METHODS: We analyzed 1666 case histories of urolithiasis patients who underwent percutaneous nephrolithotripsy/ nephrolithoextraction and contact ureterolithotripsy/ureteroextraction, we also performed a prospective analysis of complications based on the Clavien-Dindo classification in 90 patients who underwent fine fragmentation of stones with various lithotripters: ultrasonic, pneumatic, and holmium laser. The method of controlled stone fragmentation by a diode laser with a hot-spot effect was tested on postoperative samples of 26 renal calculi. For the first time in clinical practice, this method was tested in the bladder cavity (n=10). RESULTS: In the percutaneous nephrolithotripsy group, postoperative infectious and inflammatory complications occurred in 34.1% of cases, in the percutaneous nephrolithoextraction group - in 24.6%, in the contact ureterolithotripsy group - in 7.8%, in the ureterolithoextraction group - in 2.5%. The analysis made it possible to identify factors promoting the development of infectious and inflammatory complications. For the first time in clinical practice, there were successfully performed ten operations of stone fragmentation using a continuous-wave diode laser with a hot-spot effect. Controlled coarse fragmentation of stones providing the possibility to reduce the number of infectious and inflammatory complications was performed in the bladder as a model for testing the method. CONCLUSION: The method of laser-induced controlled coarse fragmentation of stones with a hot-spot effect, developed and tested in clinical practice, is promising for the prevention of infectious and inflammatory complications in patients with potentially infected stones since their fine fragmentation and, consequently, spread of stone-associated toxins and microflora within the urinary system is avoided.

Identification of layers in optical coherence tomography of skin: comparative analysis of experimental and Monte Carlo simulated images.

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.

Morphological changes in skin of different phototypes under the action of topical corticosteroid therapy and tacrolimus.

BACKGROUND/PURPOSE: The present study aimed to investigate the influence of topical corticosteroid therapy and tacrolimus on morphological indices of different skin phototypes and to optimize topical therapy using the OCT technique. METHODS: Twenty healthy volunteers aging from 20 to 30 (14 men and 6 women) took part in the study: 10 persons with skin phototype I, II and 10 persons with skin phototype V, VI. Morphological state of the skin was assessed before and during application of topical steroids of different strength and calciumneurin inhibitors for 49 days. Morphological state was studied in vivo using the optical coherence tomograph. RESULTS: Morphological manifestations of skin atrophy with the use of clobetasol propionate appear earlier than with the use of hydrocortisone 17-butyrate; this process was faster in representatives of groups V, VI. Epidermal thinning in the zone of tacrolimus application was not recorded in any phototype. CONCLUSION: Recording of early preclinical signs of epidermis thinning in the course of OCT follow-up may be an indication for changing the corticosteroid therapy by calciumneurin inhibitors, which will permit to individualize the therapy, to increase its efficacy, and to minimize the possibility of complications in each particular case.

Complex assessment of age-specific morphofunctional features of skin of different anatomic localizations.

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 properties of gold nanoparticles for optical coherence tomography: phantom, in vivo studies and Monte Carlo simulation.

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.

Optical coherence tomography monitoring for laser surgery of laryngeal carcinoma.

BACKGROUND AND OBJECTIVES: 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 T(1), T(2) stage. We used an endoscopic OCT device for imaging at a wavelength of 0.83 microm with the acquisition rate of approximately 0.5 frames/s for a single (200 x 200 pixel) tomogram. All patients were operated with a surgical YAG:Nd laser at two switchable wavelengths of 1.44 microm and 1.32 microm 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 microm and 1.44 microm 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.

High-Power As-S Glass Fiber Delivery Instrument for Pulse YAG:Er Laser Radiation.

A 3-mum laser-generation delivery instrument that uses chalcogenide fibers with a unique damage threshold and conical radiation input has been developed for medical applications. A new purification and synthesis scheme has been elaborated that yields fibers with a heterophase inclusion content of less than 10(4) cm(-3). In such fibers the damage threshold is 350 J/cm(2) at an average power density of 0.5 kW/cm(2) in a YAG:Er laser operating in the repetitive pulse free-running regime with a pulse duration of 350 ms. 1-3 x 10(4) laser pulses were transmitted at a repetition rate of 3 Hz and an average output power of 1 W under the condition of a 15% decrease in the output power.