Q-switched Ruby Laser Irradiation Research Articles

The Effects of UVA Irradiation on Depigmented Sites in the Skin of the Hairless Dog

The effects of UVA irradiation on sites of Q-switched ruby laser (QRL) irradiation were grossly and histopathologically investigated, using UVB-induced spotty pigmentation in the skin of a hairless dog. There is no experimental evidence to date that UV irradiation stimulates melanocytes and melanogenesis in skin treated with QRL irradiation. The spotty pigmentation in the skin of the hairless dog was treated with QRL irradiation. The deleterious effects of UVA irradiation on the QRL-treated sites were then examined. Two weeks after the completion of UVA irradiation, pigmentation began from the surroundings of the QRL-treated sites and/or the remaining hair follicles. Pigmentation became more prominent and the recurrence of hyperpigmentation more frequent. Histopathologically, 1 wk after QRL irradiation, there were some vacuolated dihydroxyphenylalanine (DOPA)-positive melanocytes in which melanin granules were completely destroyed. At the QRL + UVA-treated sites, the number of DOPA-positive melanocytes increased significantly from 2 wk, peaking at 4 to 6 wk after completion of UVA irradiation. From 6 wk after UVA irradiation, there was a return to a normal distribution of DOPA-positive melanocytes. In areas of recurrence of hyperpigmentation, melanin granules aggregated at the bottom of the nucleus of each epidermal cell. The lower portions of hair follicles produced an excess of melanin granules. UVA irradiation had deleterious effects on the QRL-treated sites and caused a recurrence of spotty pigmentation. Hairless dogs are useful laboratory animals for evaluating gross and histopathological changes in pigmented lesions treated with QRL irradiation.

Gene Expression Profiling of Melanocytes following Q-Switched Ruby Laser Irradiation

Background: The Q-switched Ruby laser (QSRL) is used for the treatment of pigmented lesions. The influence of QSRL treatment on gene expression of nontransformed primary melanocytes has not been addressed in vitro. Objective: We investigated the gene expression profile of melanocytes following QSRL irradiation. Methods: Primary melanocytes were irradiated with the QSRL (694 nm). Early and late transcriptional effects were analyzed using the Affymetrix gene array platform. Results: Laser irradiation of melanocytes had minor effects on mRNA expression. We found only 31 out of 14,500 genes which were at least twofold up- or downregulated. The differential expression of heme oxygenase 1 and galanin in QSRL-treated melanocytes was additionally confirmed by real-time RT-PCR. Analysis of a selection of 36 genes which are known to be associated with malignant melanoma development and progression revealed no significantly aberrant expression in the QSRL-treated melanocytes. Conclusion: Our study shows that QSRL treatment of primary melanocytes in vitro does not cause major alterations of global gene expression and particularly of genes associated with malignant melanoma. However, since QSRL treatment may have different effects on gene expression of melanocytic cells in vivo, further studies are required to evaluate QSRL treatment of (nevo-) melanocytic lesions.

Q‐switched ruby laser irradiation on spotty pigmentation in the skin of the hairless dog

OBJECTIVE: To investigate macroscopically and histopathologically the dermatological changes after Q‐switched ruby laser (QRL) irradiation with different exposure doses in UVB‐induced pigmentation in hairless dogs.METHODS: QRL irradiation with 3.0, 5.0 and 7.0 J/cm2 was carried out on the UVB‐induced spotty pigmentation in the skin of the hairless dog. Gross appearance was observed daily throughout this study. Histopathological examination was performed 1 day before QRL irradiation and 1 and 3 days and 1, 2, 3, 4, 5, 6, 7, 8, 10, 12, 14 and 16 weeks after QRL irradiation.RESULTS: Immediately after QRL irradiation, spotty pigmentation was removed. One week after QRL irradiation, re‐epithelialization started from the margin of the irradiated sites. between 5 and 10 weeks after QRL irradiation, the skin color returned to normal and some portions showed recurrence of hyperpigmentation. Histopathologically, spotty pigmentation had a heavy deposition of melanin granules in the stratum basale, spinosum and corneum. One day after QRL irradiation, the skin showed destruction of melanin granules. Seven days after QRL irradiation, re‐epithelialization began from the surroundings of the QRL‐irradiated sites and the pilosebaceous units. The delayed process of re‐epithelialization was dependent on the incident exposure dose with QRL. The repaired epidermis was devoid of melanin granules. By 5 weeks after QRL irradiation with 3.0 and 5.0 J/cm2, the stratum basale and spinosum revealed a redistribution of melanin granules. In the sites of recurrent hyperpigmentation, the bases of the remaining hair follicles showed a notable increase in the reproduction of melanin granules. Melanin granules abundantly aggregated in the bottom portion of the nucleus in each epidermal cell.CONCLUSION: These results revealed that hairless dogs were invaluable laboratory animals, which developed spotty pigmentation after successive UVB irradiation. In addition, UVB‐induced spotty pigmentation in hairless dogs is useful for investigating the process of depigmentory treatment with QRL irradiation and recurrence of this lesion.

Automated Measurement of Vacuolization of Congenital Nevi After Ex Vivo Q-Switched Ruby Laser Irradiation: Implications for Therapy.

Automated Measurement of Vacuolization of Congenital Nevi After Ex Vivo Q-Switched Ruby Laser Irradiation: Implications for Therapy.

Qスイッチルビーレーザー照射後の組織学的変化

Q-switched ruby laser is widely used in therapy of cutaneous pigmented cells. Its pulses cause selective damage to melanin granules in cutaneous pigmented cells. However, the mechanism of selective destruction of pigmented cells has not been well described. Therfore, using Mexican hairless dog descendants, we studied the histological changes after 25-ns, Q-switched ruby laser irradiation. Gross observation and light microscopy were performed. With radiant exposures of 1.5J/cm2 or greater, immediate whitening appeared, and depigmentation continued until repigmentation occured in day 28. Disruption of melanin granules was seen immediately by light microscopy. Over the next seven days, epidermal necrosis was followed by regeneration of depigmented epidermis. 28 days after irradiation, melanin garanules appeared in hair follicles and basal cell layer. By 16 weeks, melanin pigmentation had returned. The style of regeneration of melanin granules coincided with the one of human's Neavus Spilus. This study suggested the posibility of Mexican hairless dog descendants' skin as a model of epidermal pigmented lesion in human.

顔面及び頚部の扁平母斑に対するルビーレーザーによる治療

Nevus spilus is known to have a high recurrence rate following treatment with dermabrasion, cryotherapy or laser irradiation therapy while we have got much highly effect on nevus of Ota. To minimize recurrence, laser treatment was performed using a normal-pulsed ruby laser system (dual pulse width: 240μs~2ms) and Q-switched ruby laser system (pulse width: 30ns). This therapy was revealed to be highly effective as demonstrated by clinical results obtained from 36 clinical cases, and was partically usefull in treating of face and neck. After the epidermis on the treated area had been completely removed with normal-pulsed ruby laser, the addition of short pulse treatment with normal-pulsed ruby laser and more addition of Q-switched ruby laser irradiation improved reducing recurrence rate. The protokol was further improved with additional laser treatment using short pulses of 10J/cm2 and Q-switched ruby laser irradiation of 4~7J/cm2, 3 weeks after the first irradiation. The efficacy of this treatment protokol was judged excellent or good in 23 out of 36 cases (63.9%).

Q-switched ruby laser irradiation of normal human skin. Histologic and ultrastructural findings

Q-switched ruby laser irradiation of normal human skin. Histologic and ultrastructural findings

Q-Switched Ruby Laser Irradiation of Normal Human Skin

The Q-switched ruby laser is used for treatment of tatoos. The effects of Q-switched ruby laser pulses on sun-exposed and sun-protected human skin, as well as senile lentigines, were investigated with clinical observation, light microscopy, and transmission electron microscopy. A pinpricklike sensation occurred at radiant exposures as low as 0.2 J/cm2. Immediate erythema, delayed edema, and immediate whitening occurred with increasing radiant exposure. The threshold for immediate whitening varied inversely with skin pigmentation, ranging from a mean of 1.4 J/cm2 in lentigines to 3.1 J/cm2 in sun-protected skin. Transmission electron microscopy showed immediate alteration of mature melanosomes and nuclei within keratinocytes and melanocytes, but stage I and II melanosomes were unaffected. Histologically, immediate injury was confined to the epidermis. There was minimal inflammatory response 1 day after exposure. After 1 week, subthreshold exposures induced hyperpigmentation, with epidermal hyperplasia and increased melanin staining noted histologically. At higher radiant exposures, hypopigmentation occurred with desquamation of a pigmented scale/crust. All sites returned to normal skin color and texture without scarring within 3 to 6 months. These observations suggest that the human skin response to selective photothermolysis of pigmented cells is similar to that reported in animal models, including low radiant exposure stimulation of melanogenesis and high radiant exposure lethal injury to pigmented epidermal cells.

Laser and ion-beam mixing of Cu-Au-Cu and Cu-W-Cu thin films

A study of the mixing effect of Q-switched ruby laser irradiation on Cu-Au and Cu-W systems is made and a comparison with ion-beam mixing of both systems is studied. Ion-beam mixing is found to yield more uniformly mixed layers. The insoluble system, Cu-W, can only be mixed with ion impact. For a W-marker in Cu a shift in depth is observed and the variance, σ 2, of the marker distributions increases linearly with ion dose.

Luminescence of isoelectronic traps in laser-annealed, tellurium-coated zinc sulphide

The production of a single-tellurium and paired-tellurium isoelectronic trap luminescence centres in zinc sulphide by the Q-switched ruby laser irradiation of layers of thermally-deposited tellurium on the surface of zinc sulphide is described. Evidence is presented for surface melting of the zinc sulphide caused by the laser radiation. For the production of isoelectronic traps by the above-mentioned process the existence of an optimum energy of the laser radiation has been shown and its approximate value determined.

Laser pulse annealing of ion-implanted GaAs

GaAs single-crystals wafers are implanted at room temperature with 400-keV Te+ ions to a dose of 1×1015 cm−2 to form an amorphous surface layer. The recrystallization of this layer is investigated by backscattering spectrometry and transmission electron microscopy after transient annealing by Q-switched ruby laser irradiation. An energy density threshold of about 1.0 J/cm2 exists above which the layer regrows epitaxially. Below the threshold the layer is polycrystalline; the grain size increases as the energy density approaches threshold. The results are analogous to those reported for the elemental semiconductors, Si and Ge. The threshold value observed is in good agreement with that predicted by the simple model successfully applied previously to Si and Ge.

Short-channel MOS FET’s fabricated by self-aligned ion implantation and laser annealing

Short-channel MOS FET’s are successfully fabricated using Q-switched ruby laser irradiation on As-implanted sources and drains. Implantation and laser irradiation are both self-aligned by the polysilicon gate electrodes. The threshold-voltage–vs–channel-length relation is improved as a result of the extremely limited lateral diffusion of implanted As atoms.

Lattice location of Te in laser-annealed Te-implanted silicon

Backscattering of a 2.0-MeV He+ ion beam and channeling-effect techniques have been used to investigate the lattice location of Te in laser-annealed Te-implanted silicon. After Q-switched ruby-laser irradiation, an attenuation of 85% has been found in the Te signal for beam incidence along the 〈111〉 and the 〈110〉 axes of a Si crystal implanted with 400-keV Te to a dose of 1015 ions/cm2. The damaged amorphous layer recrystallizes completely after a 50-MW/cm2 pulse of 50-nsec duration for 〈111〉-oriented specimens; a lower power density is sufficient for 〈100〉 specimens. The Te profile broadens and shows accumulation at the Si surface for a power density of 60 MW/cm2 on a 〈100〉 specimen.

Structure of crystallized layers by laser annealing of 〈100〉 and 〈111〉 self-implanted silicon samples

Channeling effect techniques with a 2.0 MeV He+ Rutherford backscattering and transmission electron microscopy were used to characterize the crystallized layers after Q-switched ruby laser irradiation of 4000 A thick amorphous layer on 〈100〉 and 〈111〉 underlined crystal substrates. At a laser energy density of 2.5 J/cm2 the crystal layer on the 〈111〉 specimen contains a large density of stacking-faults, that on 〈100〉 specimen contains a very small amount of screw dislocation lines. High quality single-crystal layers have been obtained after irradiation at 3.5 J/cm2. From a comparison with the growth rate and defect structure observed in thermally annealed implanted-amorphous layers, we propose that crystal growth by 50 ns pulse laser annealing occurs by melting the amorphous layer.