Soft Laser Research Articles

Laser reactivity of NH 3 on silicon: a laser multiphoton-ionisation mass spectrometry study

Laser desorption coupled to laser multiphoton-ionisation mass spectrometry is used to study spontaneous or laser induced NH 3 reactivity on silicon surface at room temperature. A 355 nm laser, with a 4.1 ns pulse duration, is focused on a silicon surface pre-exposed to ammonia with laser energy under ablation threshold. Depending on laser irradiation energy there is desorption of species or bond modification leading to desorption of more molecules. With soft laser energy, we only detect desorbed neutral SiNH 2 molecules. This molecule is the signature of a dissociative adsorption of NH 3 on Si. From a critical laser energy E m, laser irradiation induces surface melting and we detect other desorbed species Si 2, Si–NH 2 and Si 2–NH which are characteristic of new bonding on surface. E m represents the energy threshold for silicon nitriding induced by laser.

THE EFFECT OF AGING ON MYOSIN HEAVY CHAIN CONCENTRATION IN SKELETAL MUSCLE OF YOUNG AND OLD MEN

A decrease in specific tension (SpT), or force per unit cross-sectional area of skeletal muscle, in the elderly is well documented. This decrease may be due to a decrease in the number of acto-myosin interactions, a decrease in the force per acto-myosin interaction, or a combination of both of these. We hypothesized that a decrease in the concentration of the contractile proteins would be, at least in part, responsible for the decrease in SpT observed in the elderly. To test this hypothesis, the actin and myosin heavy chain (MyHC) concentration was determined from 73 single muscle fibers from a group of young men (18–25 years) and 72 muscle fibers from old men (65–80 years). The volume of fluorescent-labeled single muscle fibers was measured using confocal microscopy and the contractile protein content was determined using SDS-PAGE with Commassie Blue staining and soft laser densitometry. The main findings of the study were as follows: 1) An aging-related decrease in muscle fiber cross-sectional area, affecting primarily muscle fibers expressing fast MyHC isoforms (Young: 4,695 ± 170μm2 vs. Old: 4,332 ± 124 μm2); 2) A significant aging-related loss of MyHC, but not actin, per unit of cell volume (MyHC: Young: 95.6 ± 4.6 O. D. units vs. Old: 87.2 ± 5.3 O. D. units). There were no differences detected in actin concentration. These data demonstrate that the decrease in SpT in the elderly is, at least in part due to a decrease in the concentration of the molecular motor protein, myosin.

Lethal photosensitization for decontamination of implant surfaces in the treatment of peri-implantitis.

Peri-implantitis is considered to be a multifactorial process involving bacterial contamination of the implant surface. A previous study demonstrated that a combination of toluidine blue O (100 microgram/ml) and irradiation with a diode soft laser with a wavelength of 905 nm results in an elimination of Porphyromonas gingivalis (P. gingivalis), Prevotella intermedia (P. intermedia), and Actinobacillus actinomycetemcomitans (A. actinomycetemcomitans) on different implant surfaces (machined, plasma-flame-sprayed, etched, hydroxyapatite-coated). The aim of this study was to examine the laser effect in vivo. In 15 patients with IMZ implants who showed clinical and radiographic signs of peri-implantitis, toluidine blue O was applied to the implant surface for 1 min and the surface was then irradiated with a diode soft laser with a wavelength of 690 nm for 60 s. Bacterial samples were taken before and after application of the dye and after lasing. The cultures were evaluated semiquantitatively for A. actinomycetemcomitans, P. gingivalis, and P. intermedia. It was found that the combined treatment reduced the bacterial counts by 2 log steps on average. The application of TBO and laser resulted in a significant reduction (P<0.0001) of the initial values in all 3 groups of bacteria. Complete elimination of bacteria was not achieved.

Soft Laser in Hypertrophic Scars

Soft Laser in Hypertrophic Scars

Decreased expression of epidermal growth factor receptor and mRNA of its ligands in Helicobacter pylori-infected gastric mucosa.

Epidermal growth factor (EGF) and TGF-alpha play a central role in maintaining gastric mucosal integrity. Little is known about the regulative role of the four other widely expressed epidermal growth factor receptor ligands, heparin-binding EGF, amphiregulin, betacellulin and cripto in the gastric mucosa. Nineteen patients with Helicobacter pylori-positive gastritis and 32 healthy controls were investigated. Mucosal mRNA expression of EGF receptor ligands was determined by quantitative PCR before and after H. pylori eradication. PCR products were analyzed by soft laser scanning densitometry. Moreover, the effect of chronic active gastritis on EGF receptor expression was assessed by [125I] EGF receptor autoradiography. Immunohistochemistry was performed for TGF-alpha to localize growth factor expression. Antral and oxyntic biopsies showed strong mRNA expressions for TGF-alpha, amphiregulin and heparin binding EGF, but not for EGF, cripto and betacellulin. mRNA expression was significantly reduced down to 50% in H. pylori infection, significantly lower compared to normal gastric mucosa, and increased after eradication therapy. Moreover, chronic gastritis was associated with decreased antral EGF receptor binding compared to healthy controls, possibly reflecting reduced autoinduction. Immunohistochemical analyses localized TGF-alpha in the cytoplasma of gastric epithelial cells and revealed its increased expression after H. pylori eradication. The data presented suggest that amphiregulin, heparin binding EGF and TGF-alpha are important EGF receptor ligands in the gastric mucosa. H. pylori infection apparently suppresses their mRNA as well as receptor expression that is reversed by H. pylori eradication. This deficiency of the gastroprotective EGF system may contribute to the gastric pathogenicity of H. pylori infection.

Combined Laser EGb 761 Tinnitus Therapy

The treatment of patients with chronic tinnitus is very problematic and therefore otologists are trying to discover more suitable courses of therapy. In this study we wanted to evaluate the outcome of using a combination of EGb 761 and soft laser therapy. We examined 120 patients with an average duration of tinnitus of 10 years. The patients underwent pure-tone audiometry, speech audiometry and objective audiometry tests. The intensity and frequency of tinnitus was also determined. EGb 761 was administered 3 weeks before starting soft laser therapy. Patients underwent 10 sessions of laser therapy, each lasting for 10 min. An improvement in tinnitus was audiometrically confirmed in 50.8% of patients: 10 dB in 18; 20 dB in 22; 30 dB in 10; 40 dB in 6; and 50 dB in 5.

Direct writing of conformal mesoscopic electronic devices by MAPLE DW

We demonstrate a novel pulsed UV laser direct writing technique called MAPLE DW for the fabrication of conformal electronic devices. MAPLE DW (matrix assisted pulsed laser evaporation direct write) is a soft laser forward transfer technique that takes place in air and at room temperature. Specific experimental results for the deposition of Ag metal and BaTiO3 composite dielectrics with electrical quality comparable to conventional thick film deposition techniques will be given as well as a discussion of the relevant issues for further electronic device improvement. The mechanism of the MAPLE DW process that makes it applicable to a broad class of electronic materials and even biomaterials is also described.

Cr:Tm:Ho:YAG (2.1 μm) and Nd:YAG (1.444 μm) pulsed-laser lithotripsy of bile duct stones

The Nd:YAG (1.444 μm) and Cr:Tm:Ho:YAG (2.1 μm) free-running laser systems of the output energy of 300 mJ per pulse and repetition rate 1 Hz have been developed and used for bile duct stones fragmentation study in vitro. A total of 67 human bile duct stones of known sizes, collected from surgical sources were used in the experiments. Insensitivity of the stones fragmentation to the type of the laser used, and insensitivity of the fragmentation efficiency to the type of stone, was observed. No pathological changes of the tissue were observed for non-human soft tissue laser irradiation (in vitro) by 1, 2, and 5 pulses of the Cr:Th:Ho:YAG radiation of the fluency of 1.6 J/cm2. The lasers are found to be good candidates for laser lithotripsy.

Arthroscopic surgery versus supervised exercises in patients with rotator cuff disease (stage II impingement syndrome): A prospective, randomized, controlled study in 125 patients with a [formula omitted] follow-up

The effectiveness of arthroscopic surgery, supervised exercises, and placebo was compared in 125 patients with rotator cuff disease (impingement syndrome stage II) in a randomized clinical trial. The median age was 48 years, and the median duration of complications was 1 to 2 years. The treatments were arthroscopic subacromial decompression performed by 2 experienced surgeons, an exercise regimen supervised for 3 to 6 months by 1 experienced physiotherapist, or 12 sessions of detuned soft laser (placebo) for 6 weeks. The criterion for success was a Neer shoulder score >80. Fifteen (50%) and 11 (22%) of the patients randomized to placebo and exercises, respectively, had surgery during the 2 1 2 - year follow-up period and were classified as having failure with the treatments. The success rate was higher (P < .01) for patients randomized to surgery (26 of 38) and exercises (27 of 44) compared with the placebo group (7 of 28). The odds ratio for success after surgery compared with exercises was 1.5 (95% confidence interval 0.6 to 3.7; P = .49). Including all patients who underwent operation, the success rate in those not on sick leave (19 of 21) before surgery was higher compared with those on sick leave (18 of 36) (adjusted odds ratio 5.6 [1.2 to 29.2]). Similar results were observed for patients not receiving versus those receiving regular pain medication before surgery (adjusted odds ratio 4.2 [1.2 to 15.8]).

Effects of Soft Laser Irradiation in Human Bone Cells and Periodontal Ligament Cells Derived from Mandible Cultured on Titanium Plates

The objectives of the present study were to evaluate the effects of soft laser irradiation for the proliferation and the differentiation of human bone cells and periodontal cells cultured on titanium plates and plastic dishes both derived from the identical donor.Bone cells derived from mandibular fragments and periodontal ligament (PDL) cells from mandibular first premolars were obtained simultaneously from the identical orthognathic patient. Both cells in the 6th passage were seeded (5×103 cells/well) in 24-well plastic culture dishes with or without titanium plates and incubation continued for 72 hours. During the incubation period, soft laser irradiation was performed none, once, twice, which were served as control, 1×laser, 2×laser, respectively. At the end of incubation period, both cells were used for the assays of DNA synthesis and alkaline phosphatase (ALP) activity. The following results were obtained:1. Bone cells cultured on plastic dishes did not show any significant change of DNA contents and ALP activity by the various time periods of soft laser irradiation. On the other hand, bone cells cultured on titanium plates showed significant increases of DNA contents and ALP activity by the soft laser irradiation, especially by 1×10 minutes laser irradiation group. In this group, the level of DNA contents and ALP activity by titanium-cultured-bone cells were significantly greater than those by plastic-cultured-bone cells.2. In case of PDL cells, the level of DNA contents and ALP activity were constant for any kind of groups with the exception of 2×10 minutes laser group which showed significant DNA increase as compared to control group, suggesting that the existance of titanium plates and/or the irradiation of soft laser were not effective for cultured PDL cells.These results suggest that the proliferation and the differentiation of bone cells cultured on titanium plates can be stimulated by the irradiation of soft laser in vitro.

Elimination of bacteria on different implant surfaces through photosensitization and soft laser. An in vitro study.

Microbiologic examinations of implants have shown that certain microorganisms described as periodontal pathogens may have an influence on the development and the progression of peri-implant disease. This experimental study aimed to examine the bactericidal effect of irradiation with a soft laser on bacteria associated with peri-implantitis following exposure to a photosensitizing substance. Platelets made of commercially pure titanium, either with a machined surface or with a hydroxyapatite or plasma-flame-sprayed surface or with a corundum-blasted and etched surface, were incubated with a pure suspension of Actinobacillus actinomycetemcomitans or Porphyromonas gingivalis or Prevotella intermedia. The surfaces were then treated with a toluidine blue solution and irradiated with a diode soft laser with a wave length of 905 nm for 1 min. None of the smears obtained from the thus treated surfaces showed bacterial growth, whereas the smears obtained from surfaces that had been subjected to only one type of treatment showed unchanged growth of every target organism tested (P < 0.0006). Electron microscopic inspection of the thus treated platelets revealed that combined dye/laser treatment resulted in the destruction of bacterial cells. The present in vitro results indicate that lethal photosensitization may be of use for treatment of peri-implantitis.

Laser's effect on bone and cartilage change induced by joint immobilization: an experiment with animal model.

Influence of low-level (810 nm, Ga-Al-As semiconductor) laser on bone and cartilage during joint immobilization was examined with rats' knee model. The hind limbs of 42 young Wistar rats were operated on in order to immobilize the knee joint. One week after operation they were assigned to three groups; irradiance 3.9 W/cm2, 5.8 W/cm2, and sham treatment. After 6 times of treatment for another 2 weeks both hind legs were prepared for 1) indentation of the articular surface of the knee (stiffness and loss tangent), and for 2) dual energy X-ray absorptiometry (bone mineral density) of the focused regions. The indentation test revealed preservation of articular cartilage stiffness with 3.9 and 5.8 W/cm2 therapy. Soft laser treatment has a possibility for prevention of biomechanical changes by immobilization.

Soft laser sputtering of the GaAlAs (100) surface

We have studied the soft laser sputtering of (100)GaAlAs with 337 nm photons, starting from the threshold for particle emission (a few tens mJ/cm2) up to about 300 mJ/cm2. Atoms and molecules sputtered from the irradiated surface are detected, their relative number measured and their time-of-flight determined using laser resonant ionisation mass spectrometry (RIMS). After laser irradiation the surface is examined by scanning electron microscopy (SEM) and electron microprobe analysis (EMA). From the shot number and the fluence dependencies of the sputtering yield, it is shown that two sputtering regimes exist. For low fluence (< 150 mJ/cm2), the sputtering results mainly from the absorption and excitation of defect sites. At higher fluences the process is similar to thermal evaporation. One observes preferential emission of As in the form of As2 molecules and the correlated Ga and Al-enrichment of the surface with formation of GaAl micron-sized structures. However, As preferential laser sputtering is rapidly counterbalanced by excess surface Ga and Al atoms leading to a stationary sputtering regime after a few thousand laser shots.

Morphological Changes with the Passage of Time of Fibroblasts After Soft Laser Irradiation

To elucidate empirical findings about the accelerated wound healing after soft laser irradiation, we examined how soft laser rays activated mouse normal fidroblasts with varying exposure conditions. Then, we observed interesting morphogical changes in the fibroblasts under the optimal exposure conditions.We used a gallium-arsenide diode soft laser system with the mean output of 2mW emmiting a beam of 904nm wavelength. The cells tested were fibroblasts from mice. We evaluated various exposure conditions on the basis of the growth of mitochondria defined by MTT colorimetry 24 hours after exposure. Next, cellular exposure was made with the optimal exposure conditions, and compared cells with and without exposure to the soft rays immediately, 5, 10, 15 and 18 hours after exposure for their morphologic changes.The optimal condition selected for the mouse fibroblasts was 4-minute A mode irradiation repeated three times. The morphologic exathination showed that those fibroblasts were originally spindle-shaped immediately after cell division in both groups. Five hours later the fibroblasts without exposure to the soft ray had changed from the spindle-shaped to polygons, while the exposed ones were spindle-shaped with long cytoplasmic filaments. Ten hours later the not exposed cells had changed to big polygonal bodies, while the exposed cells had changed to the spindle shape with several cytoplasmic filaments. Fifteen hours the not exposed cells remained the same polygonal shapes as before, while the exposed cells almost began to devide. Eighteen hours later the not exposed cells had changed in shape from polygonal to spindle-shaped, while the exposed cells had completed the cell division to be spindle-shaped with long cytoplasmic filaments. In summary, it was clearly demon strated that the soft laser rays directly act on the fibroblasts to accelerate their cell growth.(J. Jpn. Soc. Laser Dent. 7: 1-5, 1996 Reprint requests to Dr. Takagi)

口腔外科領域疾患に対する低出力レーザーの臨床効果

口腔外科領域疾患に対する低出力レーザーの臨床効果

Experience of Modified Yamamoto Scalp Acupuncture with Simultaneous Rehabilitation and Soft-Laser Therapy in Children with Cerebral Palsy

This is an account of methods developed in Czechoslovakia for the treatment of infantile cerebral palsy. Fifty eight children have been treated using a combination of scalp acupuncture, soft laser therapy and intensive exercise. The acupuncture acts as an analgesic and muscle relaxant thus allowing both passive and active exercises to be practised more effectively. Scalp acupuncture is more practical than body acupuncture as the needles are well out of the way and do not interfere with muscular movement. The neurological benefits are not confined to the development of more normal physical capacity, but extend also to an improvement in mental ability.

Soft laser sputtering of GaAs semiconductor (100) surface

We have studied the soft laser sputtering of (100)GaAs with 337 nm photons, starting from the threshold for particle emission (a few tens of mJ/cm2) to some 300 mJ/cm2 fluences. Atoms and molecules sputtered from the irradiated surface are detected, their relative number measured, and their time of flight determined using laser resonant ionization mass spectrometry. The surface after laser irradiation is examined by scanning electron microscopy and electron microprobe analysis. One observes a significant preferential emission of arsenic in the form of As2. This leads to the formation of perturbed Ga-rich surface structure which appears even at low fluence and after a few tens of laser shots on the same spot. This initial transformation seems to determine the further evolution of the irradiated surface. First, Ga atoms aggregate to form Ga islands on the surface; after a sufficient number of shots, micrometric structures are produced which finally behave as pure Ga metal. This evolution of the surface state after multipulse irradiation appears practically the same for low and medium laser fluences, the only difference being in the number of shots required to obtain the same microscopic structure. The velocity distribution of Ga atoms and As2 molecules is well fitted by half-space Maxwellian distributions. The kinetic temperatures are in broad agreement with the results obtained from a model of laser heating of the surface. The gross features of the experimental results can be interpreted from the particular thermodynamics properties of GaAs which exhibits very large As2 pressure above the solid as soon as the temperature exceeds 950 K. After a few laser shots, corresponding to particle emission from defect sites, the thermodynamics of GaAs appears to govern the further evolution of the laser-sputtered surface. Two sputtering regimes are evidenced: In the low-fluence regime (from threshold to 90 mJ/cm2) sputtering appears to be dominated by surface defect emission, whereas for higher fluences emission is more characteristic of thermal process accompanied by preferential sputtering of arsenide. According to these experimental results, a simple analytical model was developed which relates the quantitative surface to the quantitative sputtered cloud compositions.

Temporomandibular Pain Dysfunction: Can Electrotherapy Help?

Summary Temporomandibular pain dysfunction syndrome (TMPDS) comprises a variety of signs and symptoms which may be present in any combination, dependent upon the progress and stage of the disorder. The diagnostic criteria are pain on palpation of the temporomandibular joint (TMJ), muscle tenderness on examination, joint sounds, and limitation or deviation of jaw movement on opening. Headache may also be a symptom. Physiotherapy is commonly used to treat this disorder but there is little published material in the field of clinical trials comparing different methods of physiotherapy. Most reports are anecdotal. This paper reports four different physiotherapy modalities in the management of TMPDS when compared with a placebo group. Short-wave diathermy, megapulse, ultrasound and soft laser were tested. There was no statistically significant different in success rate between any of the four methods but each was significantly better than placebo treatment.

Physiotherapy in the treatment of temporomandibular joint disorders: a comparative study of four treatment methods

Temporomandibular joint pain dysfunction syndrome (TMJPDS) comprises of a constellation of signs and symptoms including joint tenderness and pain on function, restricted jaw movement, clicking, jaw locking and tenderness in the muscles of mastication. Headache may also be a feature. Physiotherapy is commonly employed in the treatment of this condition but there is little published material reporting the relative efficacy of the different types of treatment currently available. Further, no attempt seems to have been made to compare the costs of physiotherapy with other forms of treatment of this disorder such as occlusal splint therapy. This paper reports a comparative evaluation of four different physiotherapy treatments and placebo in the management of TMJPDS and comments on their cost benefit aspects compared with that of splint therapy. The four methods of physiotherapy tested were short-wave diathermy, megapulse, ultrasound and soft laser. There was no statistically significant difference in success rate between any of the four tested (range 70.4-77.7%) although each individually was significantly better than placebo treatment. The time of improvement appeared to vary between the four methods.

Soft laser sputtering of GaAs semiconductor surfaces

Soft laser sputtering of GaAs semiconductor surfaces