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The effect of low-level laser therapy (LLLT) on the healing of skin lesions has been evaluated in many studies; however, the molecular mechanisms involved in the biostimulatory effects resulting from this treatment need to be better understood. The paper aims to analyze the effects of LLLT (660 nm) at doses of 1 and 5 J/cm2 on cell viability and expression of vascular endothelial growth factor (VEGF) and interleukin (IL6) genes in L929 fibroblast cells. The dose-response curve was performed with the GaInAlAs (660 nm) laser-treated cells at energy rates of 1 and 5 J/cm2. Cell viability was quantified at 24, 48, and 72 h after irradiation and the effects of TLBP on the cytoskeleton and endoplasmic reticulum were evaluated by fluorescence microscopy and the RT-qPCR method was used for the analysis of gene expression. It was observed that the 72 h group had a statistically significant increase in cell viability compared to the 48 h group (p < 0.01) and when compared to the 72 h control (p = 0.03). In 72 h, a greater distribution of the cytoskeleton filaments and the more evident endoplasmatic reticulum was verified, indicating an increase in the protein synthesis when compared with the control group. In the expression of the VEGF gene, a significant increase of 1.98 times (p < 0.05) in the number of transcripts was observed; whereas for the IL6 gene, a decrease of the transcripts was 4.05 times (p < 0.05), both occurring within 72 h after irradiation at 5 J/cm2. The LLLT (660 nm) at the dose of 5 J/cm2 should modulate cellular viability, upregulated VEGF, and downregulated IL6 expression of messenger RNA in culture of L929 fibroblast cells. [ABSTRACT FROM AUTHOR]

The effect of wound illumination time by pulsed diode laser on the wound healing process was studied in this paper. For this purpose, the original electronic drive circuit of a 650-nm wavelength CW diode laser was reconstructed to give pulsed output laser of 50 % duty cycle and 1 MHz pulse repetition frequency. Twenty male mice, 3 months old were used to follow up the laser photobiostimulation effect on the wound healing progress. They were subdivided into two groups and then the wounds were made on the bilateral back sides of each mouse. Two sessions of pulsed laser therapy were carried along 15 days. Each mice group wounds were illuminated by this pulsed laser for 12 or 18 min per session during these 12 days. The results of this study were compared with the results of our previous wound healing therapy study by using the same type of laser. The mice wounds in that study received only 5 min of illumination time therapy in the first and second days of healing process. In this study, we found that the wounds, which were illuminated for 12 min/session healed in about 3 days earlier than those which were illuminated for 18 min/session. Both of them were healed earlier in about 10-11 days than the control group did. [ABSTRACT FROM AUTHOR]

Low-level lasers are used in general therapy and healing process due to their good photo-bio-stimulation effects. In this paper, the effects of diode laser and Nd:YAG laser on the healing process of practically managed skeletal muscle trauma has been successfully studied. Standard impact trauma was induced by using a specially designed mechanical device. The impacted muscle was left for 3 days for complete development of blunt trauma. After that it was irradiated by five laser sessions for 5 days. Two types of lasers were used; 785-nm diode laser and 1.064-nm Nd:YAG laser, both in continuous and pulsed modes. A special electronic circuit was designed and implemented to modulate the diode laser for this purpose. Tissue samples of crushed skeletal muscle have been dissected from the injured irradiated muscle then bio-chemically analyzed for the regeneration of contractile and collagenous proteins using Lowry assay for protein determination and Reddy and Enwemeka assay for hydroxyproline determination. The results showed that both lasers stimulate the regeneration capability of traumatized skeletal muscle. The diode laser in CW and pulsed modes showed better results than the Nd:YAG in accelerating the preservation of the normal tissue content of collagenous and contractile proteins beside controlling the regeneration of non-functional fibrous tissue. This study proved that the healing achieved by the laser treatment was faster than the control group by 15-20 days. [ABSTRACT FROM AUTHOR]

The aim of this in vitro study was to evaluate the effect of laser treatment on shear bond strength of a self-adhesive flowable resin composite to human dentin. Eighty extracted sound human molar teeth were used for the study. The teeth were sectioned mesiodistally and embedded in acrylic blocks. The dentin surfaces were ground wet with 600-grit silicon carbide (SiC) paper. They were randomly divided into two preparation groups: laser (Er:YAG laser, with 12 Hz, 350 mJ energy) and control (SiC). Each group was then divided into two subgroups according to the flowable resin composite type ( n = 20). A self-adhesive flowable (Vertise Flow) and a conventional flowable resin (Premise Flow) were used. Flowable resin composites were applied according to the manufacturer's recommendations using the Ultradent shear bond Teflon mold system. The bonded specimens were stored in water at 37 °C for 24 h. Shear bond strength was tested at 1 mm/min. The data were logarithmically transformed and analyzed using two-way analysis of variance and Student-Newman-Keul's test at a significance level of 0.05. The self-adhesive flowable resin showed significantly higher bond strength values to laser-prepared surfaces than to SiC-prepared surfaces ( p < 0.001). The conventional flowable resin did not show such differences ( p = 0.224). While there was a significant difference between the two flowable resin composites in SiC-prepared surfaces ( p < 0.001), no significant difference was detected in laser-prepared surfaces ( p = 0.053). The bond strength of a self-adhesive flowable resin composite differs according to the type of dentin surface preparation. Laser treatment increased the dentin bonding values of the self-adhesive flowable resin. [ABSTRACT FROM AUTHOR]

The aim of the present study was to assess the possibility to measure caries-induced laser fluorescence underneath a novel nano-filled fissure sealant. Sixty freshly extracted human teeth with occlusal dentine carious lesions were horizontally divided, exposing the respective lesion. Teeth were randomly assigned to three groups: (I) white fissure sealant with filler particles (Fissurit F, Voco), (II) clear fissure sealant without filler particles (Fissurit, Voco) and (III) novel experimental fissure sealant with nano-filler particles (Voco). Starting with a sealant thickness of 3 mm, laser fluorescence measurements (DIAGNOdent, KaVo) were performed after finishing the sealant surfaces with polishing papers, reducing the material at intervals of 0.5 mm until the sealant was removed completely. Evaluating a thickness of 0.5 mm, both the clear (83 % of the baseline fluorescence after fine grit polishing) and the white sealant (25 %) did not allow to measure baseline fluorescence ( p < 0.05) with no fluorescence reduction in the experimental sealant group ( p > 0.05). With increasing sealer thickness, fluorescence was influenced even by the experimental material (89 % of the baseline value at 1 mm). However, by using the experimental material, statistically significant higher fluorescence values than those for the other materials under study ( p < 0.05) were obtained. Thicker sealant layers and coarse grit polishing caused a decrease of laser fluorescence in all groups ( p < 0.05). Employing the experimental nano-filled sealant, laser fluorescence measurements for caries detection can be performed through thicker sealant layers compared to conventional sealant materials. Thus, it might be possible to use this material to assess a caries progression underneath the sealant and administer an appropriate therapy in due time. [ABSTRACT FROM AUTHOR]

A growing number of laboratory and clinical studies over the past 10 years have shown that low-level laser stimulation (633 or 670 nm) at extremely low power densities (about 0.15 mW/cm(2)), when administered through a particular emission mode, is capable of eliciting significant biological effects. Studies on cell cultures and animal models as well as clinical trials give support to a novel therapeutic modality, which may be referred to as ultra low level laser therapy (ULLLT). In cultured neural cells, pulsed irradiation (670 nm, 0.45 mJ/cm(2)) has shown to stimulate NGF-induced neurite elongation and to protect cells against oxidative stress. In rats, anti-edema and anti-hyperalgesia effects following ULLL irradiation were found. Clinical studies have reported beneficial effects (also revealed through sonography) in the treatment of musculoskeletal disorders. The present paper reviews the existing experimental evidence available on ULLLT. Furthermore, the puzzling issue of the biophysical mechanisms that lie at the basis of the method is explored and some hypotheses are proposed. Besides presenting the state-of-the-art about this novel photobiostimulation therapy, the present paper aims to open up an interdisciplinary discussion and stimulate new research on this subject. [ABSTRACT FROM AUTHOR]

In the present paper, the influence of tubule orientation on surface texture development was studied. Specimens of dentin with a wide range of tubule orientations were extracted from caries-free human teeth, processed using KrF laser radiation, and analyzed by scanning electron microscopy. When a transverse cross section of dentin cut perpendicularly to the tooth axis is processed with KrF laser radiation, a cone-like topography develops in the inner dentin where tubules are parallel to the laser beam. When laser processing is carried out in the outer dentin, because tubules are significantly tilted with respect to the laser beam, flat surfaces are achieved. The surface texture after laser processing depends effectively on the angle between the tubules and the laser beam. The dependency of cone growth on tubule orientation was confirmed using a simple differential ablation model. [ABSTRACT FROM AUTHOR]

. The scientific investigation of fundamental problems plays a decisive role in understanding the mode of action and the consequences of the use of lasers on biological material. One of these fundamental aspects is the investigation of the ablation threshold of various laser wavelengths in dental enamel. Knowledge of the relationships and influencing factors in the laser ablation of hard tooth tissue constitutes the basis for use in patients and the introduction of new indications. The present paper examines the ablation threshold of an Er:YAG laser (λ=2.94 µm) and an Er:YSGG laser (λ=2.79 µm) in human dental enamel. To this end, 130 enamel samples were taken from wisdom teeth and treated with increasing energy densities of 2–40 J/cm2. The sample material was mounted and irradiated on an automated linear micropositioner. Treatment was performed with a pulse duration of τP(FWHM)≈150 µs and a pulse repetition rate of 5 Hz for both wavelengths. The repetition rate of the laser and the feed rate of the micropositioner resulted in overlapping of the single pulses. The surface changes were assessed by means of reflected light and scanning electron microscopy. On the basis of the results, it was possible to identify an energy density range as the ablation threshold for both the Er:YAG and the Er:YSGG laser. With the Er:YAG laser, the transition was found in an energy density range of 9–11 J/cm2. The range for the Er:YSGG laser was slightly higher at 10–14 J/cm2. [ABSTRACT FROM AUTHOR]

Cardiovascular disease is the leading cause of death worldwide. Although cardiac transplantation is considered the most effective therapy for end-stage cardiac diseases, it is limited by the availability of matching donors and the complications of the immune suppressive regimen used to prevent graft rejection. Application of stem cell therapy in experimental animal models was shown to reverse cardiac remodeling, attenuate cardiac fibrosis, improve heart functions, and stimulate angiogenesis. The efficacy of stem cell therapy can be amplified by low-level laser radiation. It is well established that the bio-stimulatory effect of low-level laser is influenced by the following parameters: wavelength, power density, duration, energy density, delivery time, and the type of irradiated target. In this review, we evaluate the available experimental data on treatment of myocardial infarction using low-level laser. Eligible papers were characterized as in vivo experimental studies that evaluated the use of low-level laser therapy on stem cells in order to attenuate myocardial infarction. The following descriptors were used separately and in combination: laser therapy, low-level laser, low-power laser, stem cell, and myocardial infarction. The assessed low-level laser parameters were wavelength (635-804 nm), power density (6-50 mW/cm2), duration (20-150 s), energy density (0.96-1 J/cm2), delivery time (20 min-3 weeks after myocardial infarction), and the type of irradiated target (bone marrow or in vitro-cultured bone marrow mesenchymal stem cells). The analysis focused on the cardioprotective effect of this form of therapy, the attenuation of scar tissue, and the enhancement of angiogenesis as primary targets. Other effects such as cell survival, cell differentiation, and homing are also included. Among the evaluated protocols using different parameters, the best outcome for treating myocardial infarction was achieved by treating the bone marrow by one dose of low-level laser with 804 nm wavelength and 1 J/cm2 energy density within 4 h of the infarction. This approach increased stem cell survival, proliferation, and homing. It has also decreased the infarct size and cell apoptosis, leading to enhanced heart functions. These effects were stable for 6 weeks. However, more studies are still required to assess the effects of low-level laser on the genetic makeup of the cell, the nuclei, and the mitochondria of mesenchymal stromal cells (MSCs). [ABSTRACT FROM AUTHOR]

Insufficient cleaning, the complex anatomy of the root canal system, inaccessible accessory canals, and inadequate penetration of irrigants through dentinal tubules minimizes the success of the conventional endodontic treatment. Laser-assisted endodontic treatment enhances the quality of conventional treatment, but each laser wavelength has its own its own limitations. The optimal parameters for the antibacterial efficiency of a new wavelength, 1940-nm Thulium Fiber Laser, were firstly investigated in this study. This paper comprises of two preliminary analyses and one main experimental study, presents data about thermal effects of 1940-nm laser application on root canal tissue, effective sterilization parameters for bacteria, Enterococcus faecalis, and finally the antibacterial effectiveness of this 1940-nm Thulium Fiber Laser irradiation in single root canal. Based on these results, the optimal parameter range for safe laser-assisted root canal treatment was investigated in the main experiments. Comparing the antibacterial effects of four laser powers on an E. faecalis bacteria culture in vitro in 96-well plates showed that the most effective group was the one irradiated with 1 W of laser power (antibacterial effect corresponding to a log kill of 3). After the optimal laser power was determined, varying irradiation durations (15, 30, and 60 s) were compared in disinfecting E. faecalis. Laser application caused significant reduction in colony-forming unit values (CFU) compared with control samples in the 17% ethylenediaminetetraacetic acid (EDTA) group. The results of bacteria counts showed that 1 W with 30 s of irradiation with a 1940-nm thulium fiber laser was the optimal dose for safely achieving maximal bactericidal effect. [ABSTRACT FROM AUTHOR]

Although ear reconstruction technology has been highly developed in recent years, hair growth on the reconstructed ear has plagued both surgeons and patients. In this paper, the authors introduce a clinical application of intense pulsed light depilation in total auricular reconstruction. From August 2012 to August 2013, 27 patients (28 ears) suffering from congenital microtia were treated by intense pulsed light depilation (650-950-nm filter, initial fluence of 14-16 J/cm2 and gradually increased, pulse width of 30-50 ms, spot size of 20 × 30 mm2, intervals of 6-8 weeks, a total of four sessions) either before or after auricular reconstruction. According to the treatment situation at diagnosis, the patients were divided into two groups: the preoperative group and the postoperative group. There were no differences between the two groups in terms of age or initial fluence for hair removal; however, there were less treatments in the former than in the latter group (preoperative group 4.1 ± 0.3, postoperative group 4.7 ± 0.7, F = 9.10, P = 0.006), and the maximum fluence used for hair removal was lower in the former than in the latter group (preoperative group 18-20 J/cm2, postoperative group 19-22 J/cm2, F = 22.31, P < 0.001). After follow-up for ≥4-6 months, the effective rate was 100% in the preoperative group, and the effective rate was 80% in the postoperative group. Intense pulsed light depilation technology is a reasonable complementary approach to total auricular reconstruction. And preoperative depilation is recommended over postoperative depilation. The non-invasive modern photonic technology can resolve the problem of postoperative residual hair on the reconstructed auricle, improving auricular shape and increasing patient satisfaction. In addition, an adequately set preoperative hair removal area can provide surface skin that is most similar to normal auricle skin for auricular reconstruction. [ABSTRACT FROM AUTHOR]

This paper reports on the biospeckle processing of biological activity using a visualization scheme based upon the digital imaging information technology. Activity relative to bacterial growth in agar plates and to parasites affected by a drug is monitored via the speckle patterns generated by a coherent source incident on the microorganisms. We present experimental results to demonstrate the potential application of this methodology for following the activity in time. The digital imaging information technology is an alternative visualization enabling the study of speckle dynamics, which is correlated to the activity of bacteria and parasites. In this method, the changes in Red-Green-Blue (RGB) color component density are considered as markers of the growth of bacteria and parasites motility in presence of a drug. The RGB data was used to generate a two-dimensional surface plot allowing an analysis of color distribution on the speckle images. The proposed visualization is compared to the outcomes of the generalized differences and the temporal difference. A quantification of the activity is performed using a parameterization of the temporal difference method. The adopted digital image processing technique has been found suitable to monitor motility and morphological changes in the bacterial population over time and to detect and distinguish a short term drug action on parasites. [ABSTRACT FROM AUTHOR]

The use of eosin methylene blue according to Giemsa as photosensitizer is presented for the first time in this paper. The present study evaluated the potential application of chlorophyllin sodium copper salt (CuChlNa) and eosin methylene blue according to Giemsa (EMB) as antimicrobial photosensitizers (aPS) for photodynamic inactivation (PDI) of Staphylococcus aureus (gram-positive) and Escherichia coli (gram-negative) bacteria. The experiments were performed using S. aureus stain ATCC 25923 and E. coli ATCC 25922 in which five aPS concentrations (0.0, 1.0, 2.5, 5.0, 10.0, and 20.0 μM for S. aureus and 0.0, 5.0, 10.0, 20.0, 40.0, and 50.0 μM for E. coli) were prepared and added in 2 mL of a saline solution containing the bacterial inoculum. After aPS incubation, the samples were divided into two groups, one kept in the dark and another submitted to the illumination. Then, the bacterial inactivation was determined 18 h after the incubation at 37 °C by counting the colony-forming units (CFU). The results revealed that both EMB and CuChlNa can be used as aPS for the photoinactivation of S. aureus, while only EMB was able to photoinactivate E. coli. Nevertheless, a more complex experimental setup was needed for photoinactivation of E. coli. The data showed that EMB and CuChlNa presented similar photoinactivation effects on S. aureus, in which bacterial growth was completely inhibited at photosensitizer (PS) concentrations over 5 μM, when samples were previously incubated for 30 min and irradiated by a light dose of 30 J cm-2 as a result of an illumination of 1 h at 8.3 mW cm-2 by using a red light at 625 nm with a 1 cm beam diameter and output power of 6.5 mW. In the case of E. coli, bacterial growth was completely inhibited only when combining a PS incubation period of 120 min with concentrations over 20 μM. [ABSTRACT FROM AUTHOR]

This paper implemented a model study of combined electrical and near-infrared (808 nm) neural stimulation (NINS) on the bullfrog sciatic nerve. The model includes a COMSOL model to calculate the electric-field distribution of the surrounding area of the nerve, a Monte Carlo model to simulate light transport and absorption in the bullfrog sciatic nerve during NINS, and a NEURON model to simulate the neural electrophysiology changes under electrical stimulus and laser irradiation. The optical thermal effect is considered the main mechanism during NINS. Therefore, thermal change during laser irradiation was calculated by the Monte Carlo method, and the temperature distribution was then transferred to the NEURON model to stimulate the sciatic nerve. The effects on thermal response by adjusting the laser spot size, energy of the beam, and the absorption coefficient of the nerve are analyzed. The effect of the ambient temperature on the electrical stimulation or laser stimulation and the interaction between laser irradiation and electrical stimulation are also studied. The results indicate that the needed stimulus threshold for neural activation or inhibition is reduced by laser irradiation. Additionally, the needed laser energy for blocking the action potential is reduced by electrical stimulus. Both electrical and laser stimulation are affected by the ambient temperature. These results provide references for subsequent animal experiments and could be of great help to future basic and applied studies of infrared neural stimulation (INS). [ABSTRACT FROM AUTHOR]

The aim of the study is to determine the effects of low level laser therapy on tooth movement during canine distalization by evaluating IL-1β, TGF-β1 levels in gingival crevicular fluid. Maxillary first premolars of the 15 Angle Class II division I patients (12-19 years old) were extracted. Right maxillary canines were distalized by standard protocol as control group whereas the left maxillary canines distalized by laser application. A gallium-aluminum-arsenide diode laser with an output power of 20 mW was applied as five doses from the buccal and the palatal side on the day 0, and the 3rd, 7th, 14th, 21th 30th, 33st, 37th, 60th, 63th, and 67th days. Gingival crevicular fluid samples were obtained with filtration paper at the initial, 7th, 14th, and 21th days, and the IL-1ß and TGF-ß1 cytokine levels were analyzed. Orthodontic models and periodontal indices were taken initially and on the days 30th, 60th, and 90th of canine distalization period. Tooth movement was assessed by scanning models (3Shape). The amount of tooth movement in the laser group was 40% more than the control group. First day IL-1ß levels were statistically higher than initial and 21st day levels (P= 0.003, P = 0.012). The rise in IL-1ß levels caused the negative correlations between 7th day IL-1β and 21st day TGF-β1 levels describes the tissue effects of laser application. Periodontal indices showed no sign of gingival inflammation during canine distalization period. As conclusion, laser does accelerate tooth movement and could shorten the whole treatment duration. [ABSTRACT FROM AUTHOR]

Optical neural stimulation in the cochlea has been presented as an alternative technique to the electrical stimulation due to its potential in spatially selectivity enhancement. So far, few studies have selected the near-infrared (NIR) laser in cochlear neural stimulation and limited optical parameter space has been examined. This paper focused on investigating the optical parameter effect on NIR stimulation of auditory neurons, especially under shorter pulse durations. The spiral ganglion neurons in the cochlea of deafened guinea pigs were stimulated with a pulsed 810-nm NIR laser in vivo. The laser radiation was delivered by an optical fiber and irradiated towards the modiolus. Optically evoked auditory brainstem responses (OABRs) with various optical parameters were recorded and investigated. The OABRs could be elicited with the cochlear deafened animals by using the 810-nm laser in a wide pulse duration ranged from 20 to 1000 μs. Results showed that the OABR intensity increased along with the increasing laser radiant exposure of limited range at each specific pulse duration. In addition, for the pulse durations from 20 to 300 μs, the OABR intensity increased monotonically along with the pulse duration broadening. While for pulse durations above 300 μs, the OABR intensity basically kept stable with the increasing pulse duration. The 810-nm NIR laser could be an effective stimulus in evoking the cochlear neuron response. Our experimental data provided evidence to optimize the pulse duration range, and the results suggested that the pulse durations from 20 to 300 μs could be the optimized range in cochlear neural activation with the 810-nm-wavelength laser. [ABSTRACT FROM AUTHOR]

After publication of this paper, the authors determined an error in Fig. 1. [ABSTRACT FROM AUTHOR]

The cervix is composed of layers of squamous epithelium and connective tissue. The main component of the cervical connective tissue is collagen, which has specific orientations in different parts of the cervix and provides mechanical strength. Cervical pathologies such as cervical intraepithelial neoplasia (CIN), cancer, pregnancy, and spontaneous preterm birth (sPTB) allow for structural remodeling of both squamous epithelium and connective tissue. Mueller matrix (MM) polarimetry is an optical imaging technique that uses polarized light to characterize the morphologic changes in pathological cervix. In this study, advances in MM polarimetry in characterizing cervical tissue and associated pathologies were reviewed. In particular, the basic structure of the MM polarimeter is described. The interaction of polarized light with cervical tissue in terms of polarimetric parameters such as depolarization and birefringence is discussed. The assessment of cervical pathologies including CIN, cancer, pregnancy, and sPTB with MM polarimetry and the underlying reasons that produce the contrast in optical imaging are outlined. The clinical implementation of MM polarimetry, especially the Müller polarimetry colposcope, is also discussed. Finally, the challenges for MM polarimetry in cervical clinics are also speculated., (© 2023. The Author(s), under exclusive licence to Springer-Verlag London Ltd., part of Springer Nature.)

This paper seeks to optimize the parameters of interstitial laser photocoagulation, and clarify controversies regarding the effect of three types of fibre tips used in percutaneous application on the size of thermal lesions produced. Bare-cut, pre-charred and conical diffused tips of 600 µm silica core fibre were compared using a diode laser (805 nm) applied in vitro using fresh porcine livers. Continuous wave laser radiation at 805 nm was applied at 1.0, 1.5, 2.0 and 2.5 W for 5, 10 and 15 min. The sizes of the resultant lesion, cavity and char were measured and analysed using the method of analysis of variance for statistical significance. It is concluded that the fibre tips do not significantly affect the lesion size (p> 0.05). Conical fibre tips produced less char when applied for 10 min or more at 2–2.5 W. Laser power and irradiation time affect the lesion size significantly (p< 0.05), and the size of the lesion produced depends on both laser power and irradiation time, not merely on the total laser energy applied. [ABSTRACT FROM AUTHOR]

This paper presents a brief overview of several techniques developed for the analysis of blood microcirculation in vivo. Both theoretical and experimental investigations have been performed using focused Gaussian beams, which are diffracted by blood capillaries with diameters slightly larger than the erythrocyte. Speckle interferometry, utilizing the diffraction of a focused Gaussian beam, was used for the analysis of lymph circulation in native microvessels. The spectra of scattered intensity fluctuations produced by diffraction in such capillaries are analysed, and variations in the envelope of the spectra induced by the influence of drugs on the lymph vessels have also been studied. [ABSTRACT FROM AUTHOR]

This paper presents a brief overview of several techniques developed for the analysis of blood microcirculation in vivo. Both theoretical and experimental investigations have been performed using focused Gaussian beams, which are diffracted by blood capillaries with diameters slightly larger than the erythrocyte. Speckle interferometry, utilizing the diffraction of a focused Gaussian beam, was used for the analysis of lymph circulation in native microvessels. The spectra of scattered intensity fluctuations produced by diffraction in such capillaries are analysed, and variations in the envelope of the spectra induced by the influence of drugs on the lymph vessels have also been studied. [ABSTRACT FROM AUTHOR]

Recent studies have shown that laser therapy can reduce the mortality and morbidity associated with Twin-Twin Transfusion Syndrome in the second trimester of pregnancy. The purpose of this paper is to analyse current treatment strategies using laser surgery, and to suggest ways in which fetal mortality may be further reduced. [ABSTRACT FROM AUTHOR]

Remodelling of deformed cartilaginous tissue in the head and neck presents a difficult surgical problem since cartilage tends to return to its original shape because of its natural internal stresses. This is also true of cartilage autografts. Cartilage can be remodelled using heat and this paper describes the use of light from a carbon dioxide laser (λ=10.6 μm) to remodel cartilaginous tissue, in a procedure which we have called laser thermochondroplasty. Straight cartilage samples were removed from the ears of 12 rabbits, moulded with the CO laser at an output power of 3 W with a spot diameter of 2 mm and exposure times of 0.5 s. After remoulding, the cartilage, together with a control, unmoulded sample, were implanted into the rabbits' back and retrieved 6-8 months later. Histological and morphological analysis showed that the treated cartilages retained both their shape and viability. This may well be a useful clinical technique for the in situ remoulding of difficult cartilage, such as that found in the nasal septum, with minimal damage, and the transplanting of autologous cartilage which has been remoulded in vitro. [ABSTRACT FROM AUTHOR]

This paper reports on the initial clinical experience with 308 nm XeCl-excimer laser coronary angioplasty (ELCA) in the Academic Medical Center in Amsterdam and on calculations of light fluence rate distributions resulting from laser beams incident on tissue. Monte Carlo numerical computations were used to compute the light fluence rate distributions of a finite 308 nm excimer laser beam with various diameters incident on a liquid-tissue interface. It was found that light scattering is an important component in the resulting light distribution in aortic tissue. The calculations predict that there will be hardly any broadening of the beam outside the laser beam area. Therefore, the distributions from different fibres in multifibre catheters will not overlap unless the fibres are closely packed together. As a consequence of scattering the fluence rate at the surface of the tissue was larger than the incident power density and showed a considerable decrease from the centre to the edge of the beam. However, the physics of tissue ablation by fibres in contact with tissue are different and at present not well understood. The clinical results of the first 18 patients treated with the Dymer 200+ excimer laser (Advanced Interventional Systems, Irvine, CA, USA) are given. Six patients had abrupt closure solved by balloon angioplasty, but complicated by a small myocardial infarction. One patient had emergency by-pass surgery for abrupt closure after laser followed by balloon angioplasty (probably a dissection and thrombus). In one patient we perforated in a bend of a RCA with a 2.0 catheter following a second pass. We had two in hospital deaths (4 and 14 days after treatment). At 6 months follow-up, eight patients had restenosis or occlusion at the lased segment. However, the results of the first 1000 patients enrolled in the American ELCA-Registry are more promising. In the light of these results it can be concluded that a randomized trial balloon angioplasty versus excimer laser angioplasty appears to be indicated. [ABSTRACT FROM AUTHOR]

This paper reports the successful experimental studies of a laser detonating a mini-explosive head to break stones in vitro and in vivo. This technique has been used clinically with gastric bezoars since January 1988. All 31 patients were completely cured without complications. The relationship between gastric bezoars and ulcers and the treatment technique are also discussed in this paper. Diospyrobezoar is one of the common bezoars in the persimmon producing regions. This disease has been reported in many countries including our own, but until now there has been no effective treatment for large gastric bezoars except by surgery. To develop a better treatment for this problem the laser ignited mini-explosion technique to break large bezoars in vitro and in vivo was begun in October 1986 and first successfully applied clinically in January 1988. [ABSTRACT FROM AUTHOR]

In laser photodynamic therapy (PDT) fibres tippe with diffusing bulbs may be used to illuminate cavities such as are encountered in the bladder or in the ear, nose and throat. However, such bulbs may absorb so much light themselves that they heat up and are destroyed, particularly those used in air cavities. This paper presents graphs which predict the bulb temperature rise, and can be used to design a bulb which scatters light well enough to provide good, all-round illumination, but, at the same time, will not be damaged by excessive rises in temperature. [ABSTRACT FROM AUTHOR]

Knowledge of the radiant energy fluence rate in tissues during laser irradiation is important for the understanding and improvement of the results of preclinical as well as clinical treatments. Quantitative data are extremely rare, however. In this paper, quantitative measurements of energy fluence rates are reported, in vitro as well as in vivo, with emphasis on light dosimetry for photodynamic therapy. Examples are given of fluence rate distributions that may occur during surface irradiation, intracavity irradiation of hollow organs (bladder) and interstitial irradiation. For the same incident irradiance, the energy fluence rate in tissue may vary considerably, depending on type of tissue, wavelength and geometry. During experimental and clinical interstitial PDT-treatments a considerable decrease in light penetration into tumours was observed, apparently indicating changes in optical properties as a result of treatment. This demonstrates the importance of in vivo light dosimetry. [ABSTRACT FROM AUTHOR]

This paper reports on the application of the motion history image (MHI) method on dynamic laser speckle processing as a result of a specific drug action on Trypanosoma cruzi parasites. The MHI procedure is based on human action recognition, and unlike other methods which use a sequence consisting of several frames for recognition, this method uses only an MHI per action sequence for recognition. MHI method avoids the complexity as well as the large computation in sequence matching-based methods and detects a change in the speckle pattern. Experimental results of MHI on real-time monitoring of activity (motility) under the influence of the drug demonstrate the effectiveness of the proposed method. The MHI showed an online result without loss of resolution and definition if we compare with routine LASCA method. The obtained results highlight the advantage of the MHI analysis over traditional qualitative image intensity-based methods and demonstrate the potential of measuring the activity of parasites via dynamic laser speckle analysis. The data was further numerically analyzed in the time domain, and the results presented the ability of the technique to monitor the action of the drug, particularly Epirubicin (100 μg/ml). [ABSTRACT FROM AUTHOR]

This paper presents the results of endovenous laser ablation (EVLA) of varicose veins in vitro using radiation of a solid-state laser based on the crystal LiYF4:Tm, with a wavelength of 1.885 μm and power output of around 3 W. An experimental series with saline solution and red blood cell (RBC) suspension in the venous lumen was performed to identify the impact of a heated carbonized layer precipitated on the fiber end face versus the efficiency of EVLA. Results of these experiments confirmed that the presence of a heated carbonized layer on the fiber end face increases the efficiency of EVLA. [ABSTRACT FROM AUTHOR]

Low-intensity laser irradiation (LILI) can improve the deformability of red blood cells (RBCs). It might be due to the LILI effects on adenosine triphosphate (ATP) level. However, ATP content may not be a valid surrogate marker for RBC deformability. The LILI effects on RBC glycolysis were studied in this paper. Hypertonic RBCs were used in this study. After 5 min irradiation with low-intensity He-Ne laser irradiation (LHNL) at 632.8 nm and 4.4 mW/cm(2), the concentration of intracellular glucose and the activities of phosphofructokinase (PFK) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) were measured, respectively. There was no significant change in intracellular glucose concentration. The activity of PFK decreased significantly, but the activity of GAPDH increased significantly. In hypertonic RBCs, LHNL irradiation may decrease the activity of energy-consuming enzymes, but increases the activity of energy-generating enzymes in glycolysis, to improve the RBC deformability. [ABSTRACT FROM AUTHOR]

Vascular anomalies of the head and neck are common lesions usually associated with functional and/or aesthetic limitations. The aim of the present paper was to report a case series of oral vascular malformations treated with Nd:YAG laser photocoagulation, highlighting the clinical evolution and post-surgical complications. Fifteen patients diagnosed with oral vascular malformations were treated with Nd:YAG laser followed by three sessions of biostimulation. None of the patients presented post-surgical pain, but 6 of 15 patients (40%) experienced minimal post-surgical complications. All cases presented complete resolution of the lesions after laser treatment. More importantly, 12 out of 15 (80%) resolved after a single session. Low morbidity, minimal patient discomfort, and satisfactory aesthetic results point Nd:YAG laser photocoagulation as a promising option for the management of benign oral vascular lesions. [ABSTRACT FROM AUTHOR]