Action spectrum of vascular specific injury using pulsed irradiation

It has been clearly demonstrated that cutaneous blood vessels will be selectively damaged by a laser whose wavelength matches one of the three absorption spectral peaks of the chromophore, oxyhemoglobin, for example, 577 nm. A restriction in the application of this wavelength for the treatment of benign cutaneous vascular tumors, such as portwine stains, has been the penetration depth of 577 nm irradiation of approximately 0.5 mm from the dermal epidermal junction (DEJ). This study was undertaken to establish whether it was possible to increase the penetration depth from 0.5 mm by changing the wavelength to beyond 577 nm in albino pig skin. Results from this study confirm that penetration depth increases from 0.5 to 1.2 mm by changing the wavelength from 577 to 585 nm at 4 J/cm2, while maintaining the same degree of vascular selectivity as that previously described after 577 nm irradiation. This occurred in spite of a mismatch in the wavelength between 585 nm and the oxyhemoglobin absorption peak of 577 nm. Unlike 585 nm irradiation and in contrast with theoretical predictions, 590 nm laser light did not penetrate as deeply as 585 nm. Not only was there a reduction in the penetration depth of the laser beam from 1.2 mm at 585 nm to 0.8 mm at 590 nm, at 4 J/cm2, but there was also a decrease in vascular selectivity in albino pig skin exposed to 590 nm irradiation.     

Effect of skin temperature on selective vascular injury caused by pulsed laser irradiation

The effect of skin temperature on vascular-specific injury caused by pulsed laser irradiation was examined. Ten healthy human volunteers were exposed to 1.5 microsecond pulses from a dye laser tuned to 577 nm. Compared to normothermic conditions (33 degrees C skin temperature) significantly more laser energy (p less than 0.01) was required to produce grossly visible purpura when the skin was cooled to 20 degrees C or heated to 40 degrees C. Histologically, laser-induced damage was confined to blood vessels at all three skin temperatures studied. At purpura threshold dose, there was intravascular agglutination without extravasation of red blood cells at 20 degrees C whereas at 33 degrees and 40 degrees C there was extravasation of red blood cells.     

Ultrastructure: effects of melanin pigment on target specificity using a pulsed dye laser (577 nm)

It has been shown recently that brief pulses of 577 nm radiation from the tunable dye laser are absorbed selectively by oxyhemoglobin. This absorption is associated with highly specific damage to superficial vascular plexus blood vessels in those with lightly pigmented (type I-II) skin. To determine whether pigmentary differences in the overlying epidermis influence this target specificity, we exposed both type I (fair) and type V (dark) normal human skin to varying radiant exposure doses over 1.5-microsecond pulse durations from the tunable dye laser at a wavelength of 577 nm. Using ultrastructural techniques, we found in type I skin that even clinical subthreshold laser exposures caused reproducible alterations of erythrocytes and adjacent dermal vascular endothelium without comparable damage to the overlying epidermis. In contrast, degenerated epidermal basal cells represented the predominant form of cellular damage after laser exposure of type V skin at comparable doses. We conclude that epidermal melanin and vascular hemoglobin are competing sites for 577 nm laser absorption and damage, and that the target specificity of the 577 nm tunable dye laser is therefore influenced by variations in epidermal pigmentation. This finding is relevant to the clinical application of the tunable dye laser in the ablative treatment of vascular lesions. We also found on ultrastructure that the presence of electron-lucent circular structures of approximately 800 A in diameter were observed only at and above clinical threshold doses in those with type I skin and at the highest dose of 2.75 J/cm2 in type V skin. It has been proposed that these structures might be heat-fixed molds of water vapor. Both this and ultrastructural changes of epidermal basal cells demonstrate mechanisms responsible for alteration of tissue after exposure to 577 nm, which are discussed.     

Spotsize effects on guinea pig skin following pulsed irradiation

Laser irradiation parameters such as wavelength, irradiance (W/cm2), and pulse duration have been clearly shown to influence the extent to which tissue is damaged. The careful choice of these parameters can result in confining laser injury to specific targets in tissue. Spotsize, a parameter not commonly appreciated in the application of lasers to medicine and surgery, has been shown, in this study, to contribute to the ultimate outcome of laser effects in tissue. A series of histological events occurring in the skin are demonstrated to be directly related to the effects of spotsize on tissue at a fixed exposure time and wavelength. Many of these changes could contribute to unwanted adverse effects, such as scarring, which occur following certain laser therapies.     

Selective heat therapy in cutaneous leishmaniasis: a preliminary experience using the 585 nm pulsed dye laser

Aim The purpose of this paper is to examine the effect of the yellow pulsed dye laser on the natural history of cutaneous leishmaniasis (CL). Materials and methods A 31 year old Saudi patient suffered from CL due to L. tropica. He was treated with 585 nm. 450 μs flashlamp pulsed dye (FLPD) laser. The patient received two laser sessions, 2 weeks apart using 5 mm spot size with a fleunce range of 8–8.5 J/cm². Results The lesion healed completely within 6 weeks with hyperpigmentation. At 16 weeks, the skin exhibited excellent texture with no scarring or recurrence. Discussion The ability to achieve a high temperature at structures or individual cells with minimal injury in healthy tissue and/or selective destruction of superficial dermal capillaries may in theory explain the possible efficacy of FLPD laser in CL. However, the exact mechanism(s) remains unknown. Conclusion The use of FLPD laser may promise local, practical, and a safe alternative form of heat therapy in CL. It has a unique advantage of possible scar improvement. Further extensive well-controlled studies are indicated.     

The pulsed dye laser for cutaneous vascular and nonvascular lesions

The pulsed dye laser was originally developed for the treatment of vascular lesions, especially hemangiomas and port-wine stains. The central concept of pulsed-dye laser is to preserving the epidermis by allowing hemoglobin to be more precisely targeted within lesions. More recently, the pulsed dye laser has also been used in the treatment of a wide spectrum of nonvascular lesions. Because of its safety profile, and its selectivity in targeting lesions, therapists can comfortably treat a wide variety of lesions in all age groups and anatomic sites.     

Influence of UVA and UVB irradiation on hepatic and cutaneous P450 isoenzymes

The influence of UVA and UVB irradiation of the skin for 1, 2 and 4 weeks on the activities of the hepatic and cutaneous P450 isoenzymes was investigated in female Wistar rats before and after systemic administration of hexachlorobenzene (HCB), a well-known porphyrogenic agent, which additionally induces P450 1A1 and P450 1A2 isoenzymes. UVA and UVB irradiation of the skin of the controls and HCB-treated animals did not influence porphyrin metabolism. In the nonporphyric rats hepatic EROD (P450 1A1) activity was induced by UVB, but the activity of ADM (P450 2B) and EMDM (P450 3A) was either minimally or not affected. In the HCB-treated (porphyric) rats UVA and UVB irradiation resulted in a significant depression of HCB-induced EROD in the liver and in the skin. In both the nonporphyric and the porphyric rats UVA and UVB irradiation had no effect on hepatic ADM activity. In the liver of the nonporphyric animals EMDM activity remained unchanged after UVA and UVB irradiation, whereas in the HCB-treated animals the activity of this enzyme was increased. Finally, after UVA and UVB irradiation cutaneous EMDM activity was increased in the controls, whereas the HCB-induced increase of this enzyme in porphyric animals was decreased. In addition long-term (28 days) UVB irradiation decreased hepatic GSH content significantly in normal and porphyric rats. These experimental findings cannot be directly extrapolated to humans; however, they suggest that exposure of human skin to UV radiation may result in alterations in the activity of cutaneous, hepatic and other extracutaneous P450 isoenzymes. Received: 27 June 1996     

Tunable pulsed dye laser for the treatment of benign cutaneous vascular ectasia

A tunable pulsed dye laser emitting at 577 nm and 360 microseconds pulse width was used to treat benign cutaneous vascular ectasias other than port wine stain in 77 patients. Except for leg telangiectasias (34 patients), the overall response was excellent. Forty-two of forty-five patients with hemangiomas, spider nevi, angioma serpiginosum, venous lakes or facial telangiectasias showed excellent results after 1-4 consecutive treatments. Scarring was observed in none of the patients. These results confirm previous data on the use of the tunable dye laser in the treatment of port wine stain, and suggest that 577 nm wavelength and 360 microseconds pulse width allow the selective photothermolysis of vascular cutaneous ectasias with better clinical results than previously reported.     

An update on cutaneous aging treatment using herbs

Skin aging is caused by several factors. Ultraviolet (UV) exposure as well as oxidative stress elevates inflammatory mediators causing degradation of the extracellular matrix, which is regarded as the major cause of skin wrinkles, one of the signs of aging. Topical applications of active ingredients protect against dermal photodamage and scavenge radicals that can delay skin aging. Matrix metalloproteinase inhibitors against degradation of collagen, elastin, and hyaluronan are the key strategy to combat cutaneous aging. In addition, active ingredients with the efficacy to enhance extracellular matrix production, including those with UV protection efficacy, play an important role in protecting the skin from aging. Naturally derived compounds for combating skin wrinkles are gaining more interest among the consumers as they are perceived to be milder, safer, and healthier. This article, therefore, briefly addresses the causes of skin aging and extensively summarizes on herbs appraisal for skin wrinkles treatment. Therefore, delaying aging of skin using the functional herbs would maintain the individual's appearance with high esthetic and psychosocial impacts.     

Ultrastructural changes in red blood cells following pulsed irradiation in vitro

The careful choice of a combination of laser parameters such as wavelength, pulse duration, and dose has provided a means for confining laser energy to specific targets within tissue such as oxyhemoglobin within the cutaneous microvasculature. In the process of achieving such vascular selectivity, certain ultrastructural changes in red blood cell (RBC) cytoplasm have been observed, such as the generation of intracytoplasmic electron-lucent spherical structures. These structures, ranging in size from 80 to 1000A, were seen in RBCs exposed to laser doses at and above threshold, and appeared to represent a morphologically novel form of highly-specific tissue injury. This in vitro study using RBC in phosphate buffered saline (PBS) was undertaken to better understand the mechanism(s) that could have been responsible for these unique morphologic changes. We conclude that the intracytoplasmic electron-lucent spherical structures seen within RBCs were heat-fixed molds formed around vaporized water bubbles and were not produced by the release of oxygen from the oxyhemoglobin moiety during 577-nm laser irradiation.     

Successful treatment of porokeratosis with 585 nm pulsed dye laser irradiation.

Porokeratosis, a keratinization and fibroblast cutaneous disorder, is a progressive disease with limited treatment options. We describe a case of linear porokeratosis that responded favorably to a series of 585 nm pulsed dye laser treatments. In addition to its vascular specificity, the pulsed dye laser presumably produces a direct effect on collagen, as well as an indirect effect on histamine and mast cells that could account for the clinical changes seen in our patient.     

Hand rejuvenation using intense pulsed light

BACKGROUND: The aging of the hands is typically characterized by wrinkles, skin thinning, and solar lentigines. The search for effective treatments has led to the use of laser and intense pulsed light (IPL) technologies. OBJECTIVE: To assess the effectiveness of an IPL device for the improvement of dyspigmentation and overall skin quality on the dorsa of the hands. METHODS: Twenty-three patients with sun damage and solar lentigines on the dorsal hands were treated with four IPL sessions at 3- to 4-week intervals. Prior to treatment, photographs were taken and informed consent was obtained. Pre- and post-treatment photography and investigator clinical assessment and patient questionnaires were collected for data analysis. RESULTS: After four treatment sessions, good to excellent results in the improvement in solar lentigines and skin quality were assessed by investigators in 100% of the cases and in 86.94% (20 of 23 subjects) by patient self-assessments. No significant side effects were observed. CONCLUSION: IPL is an effective and safe treatment option to improve solar lentigines and skin texture for hand rejuvenation.     

The effect of pulsed dye laser on cutaneous leishmaniasis and its impact on the Dermatology Life Quality Index

Background and objective: Cutaneous leishmaniasis is a prevalent skin condition especially in the Middle Eastern region. The use of pulsed dye laser (PDL) for the treatment of cutaneous leishmaniasis (CL) has not been thoroughly evaluated. We assessed primarily the efficacy of 595-nm PDL in the treatment of CL lesions and interpreted its impact on the quality of life (QOL) of affected patients as measured by the Dermatology Life Quality Index (DLQI). Patients and methods: Twenty-five lesions from 12 patients were treated with a single pass of PDL over the whole lesions to develop a purpuric end point. Parameters used for this treatment were 7 J/cm² fluence, 10-mm spot size, and 0.45-ms pulse duration. The laser settings were maintained in all subsequent treatments. Results: Excellent response was noted in 13 of the 25 lesions after 3 sessions, while 12 of the remaining 25 lesions required 4 sessions toward complete recovery. The mean DLQI scores pre- and post-laser treatments were 12.67 and 4.25, respectively. All patients experienced a statistically significant improvement in their QOL (p < 0.05, paired t-test). Conclusion: The PDL is a new safe modality for treating cases of CL with further larger-scale studies could better determine its role.