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Biomedical subjects

R R Anderson

Publications and source records attributed to R R Anderson.

At least 91 records · Page 5Linked to original sources
PubMed1996

Motivation for tattoo removal.

BACKGROUND AND DESIGN: Motivational issues surrounding tattoo removal are important to understand because tattooing is flourishing, thus creating many requests for tattoo removal. A descriptive study and a 67-item survey were used to examine characteristics of tattooed patients seeking laser therapy for tattoo removal. The setting was the Laser Dermatology Center, Massachusetts General Hospital in Boston, a large metropolitan ambulatory clinic. Patients queried were 64 tattooed males and 41 tattooed females between the ages of 17 and 62 years with a wide variety of vocational and professional occupations. We assessed risk factors surrounding tattooing decisions and experiences that might later influence their motivation to have the tattoos removed by laser therapy. RESULTS: Motivation, treatment, and cost, in terms of money, pain, and risk of disfigurement all entered into the decision making to have the tattoos removed. Strong elements of purchase and possession risks were documented as well as an improved sense of self and maturity. The patient's maturation was in contrast to the notion of a waiting room filled with ill-behaved stereotypical tattooed individuals. Most participants impulsively obtained their tattoos for internal expectations of self-identity at an early age and were still internally motivated to dissociate from the past and improve self-identity. CONCLUSIONS: Poor decision making and subsequent personal regret seem to be frequent motivations for tattoo removal, thus viable methods and accessibility to tattoo removal programs are important. In addition, educational programs for adolescents about tattooing to reduce risks and promote dissuasion should be implemented.

Adolescent↗
PubMed1995

Lack of selectivity of protoporphyrin IX fluorescence for basal cell carcinoma after topical application of 5-aminolevulinic acid: implications for photodynamic treatment.

Clinical trials of topical ALA in photodynamic therapy (PDT) of basal cell carcinoma (BCC) show significant recurrence rates. Exogenous 5-aminolevulinic acid (ALA) is converted by intracellular enzymes to photoactive protoporphyrin IX (PpIX) in human tissues. PpIX generates cytotoxic singlet oxygen when irradiated with visible light in the 400-640 nm range. To evaluate variability and heterogeneity in PpIX production by tumors in such trials, and to assess the usefulness of PpIX for marking skin tumors, we measured PpIX fluorescence distribution in BCC after topical application of 20% ALA cream. ALA cream was applied under occlusion for periods ranging from 3 to 18 h (average 6.9 h, SD 4 h) to 16 BCCs. ALA conversion to PpIX in the BCCs was assessed by in vivo photography, ex vivo video fluorescence imaging, and fluorescence microscopy. External macroscopic PpIX fluorescence, as assessed by in vivo and ex vivo imaging, correlated with the clinical presence of BCC. Examination by a digital imaging fluorescence microscope revealed inter- and intratumor fluorescence variability and heterogeneity. PpIX fluorescence corresponding to full tomor thickness was found in six superficial and four nodular tumors, and partial-thickness fluorescence was observed in five nodular tumors, but no PpIX fluorescence was observed in some areas of superficial, nodular and infiltrating tumors. In a significant number of nodular and infiltrating BCCs, topical ALA appeared to provide little or no PpIX in deep tumor lobules. In addition, no selectivity for tumor tissue versus normal epidermis was seen. The grossly brighter external PpIX fluorescence over tumors may be due, therefore, to enhanced penetration through tumor-reactive stratum corneum and to the tumor thickness.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Cutaneous↗
PubMed1995

Polarized light photography in the evaluation of photoaging.

BACKGROUND: The clinical characteristics of photodamaged skin, such as coarse and fine wrinkling, sallowness, hyperpigmentation, tactile roughness, laxity, and erythema, are not accurately evaluable from photographic records. OBJECTIVE: The purpose of this study was to develop accurate and reproducible photographic techniques that generate an evaluable record of the characteristics of photodamaged skin. METHODS: The method used involved illumination and photography through polarizing filters (polarized light photography). RESULTS: Polarized light photography generates images that selectively enhance either the surface features or the subsurface features of the skin, providing an accurate and evaluable record for evaluation of photodamaged skin. CONCLUSION: Polarized light photography, when coupled with precise framing and mapping, yields an accurate and evaluable record of photodamaged skin.

Humans↗
PubMed1995

Thermal relaxation of port-wine stain vessels probed in vivo: the need for 1-10-millisecond laser pulse treatment.

Although thermal relaxation times of cutaneous port-wine stain microvessels have been calculated and used to formulate laser selective photothermolysis, they have never been measured. A scheme to do so was devised by measuring the skin response to pairs of 585-nm dye laser pulses (250-360 microseconds each) as a function of the time interval between the two pulses, in five volunteers with port-wine stains. After a pump pulse delivering 80% of the fluence necessary for causing purpura, the fluence of a second probe pulse necessary to cause purpura was determined and was found to increase with the interval between the two pulses, in a manner consistent with thermal diffusion theory. Biopsy specimens were obtained from four of the five subjects to examine the nature and extent of vessel damage and to measure the port-wine stain vessel diameters. Using diffusion theory, the thermal relaxation time was calculated based on the measured vessel diameters. These calculated values are consistent with the increase in radiant exposure (fluence) of the probe pulse necessary to induce purpura for longer time delays. Two simple models for thermal relaxation of port-wine stain vessels are presented and compared with the data. The data and histologic assessment of the vessel injury strongly suggest that pulse durations for ideal laser treatment are in the 1-10-millisecond region and depend on vessel diameter. No dermatologic lasers presently used for port-wine stain treatment operate in this pulse width domain.

Adult↗
PubMed1995

In vivo confocal scanning laser microscopy of human skin: melanin provides strong contrast.

Confocal scanning laser microscopy of live human skin was performed to investigate the correlation of in vivo cellular and morphologic features to histology, the effect of wavelength on imaging, and the role of melanin as a contrast agent. We built a video-rate confocal scanning laser microscope for in vivo imaging of human skin. Using a 100 x microscope objective, we imaged high-contrast optical "sections" of normal skin, vitiliginous skin, and a compound nevus. In vivo "confocal histology" correlated well with conventional histology. The maximum imaging depth increased with wavelength: the epidermis was imaged with visible 400-700-nm wavelengths; the superficial papillary dermis and blood cells (erythrocytes and leukocytes) in the deeper capillaries were imaged with the near infrared 800-900-nm wavelengths. For confocal reflectance imaging, melanin provided strong contrast by increased backscattering of light such that the cytoplasm in heavily pigmented cells imaged brightly. In vivo confocal microscopy potentially offers dermatologists a diagnostic tool that is instant and entirely non-invasive compared to conventional histopathology.

Contrast Media↗
PubMed1995

Basic mechanism of in vitro pulsed-dye laser-induced vasodilation.

Vasodilation of rabbit carotid arteries induced by a pulsed-eye laser was studied in vitro to clarify the underlying mechanism. Artery segments were double cannulated in a pressure-perfusion apparatus which, under physiological conditions, allows for differential application of various solutions, pharmacological agents, and pulsed-dye laser light. Vasoconstriction was activated using both pharmacological and nonpharmacological agonists. Laser energy at a wavelength of either 480 or 575 nm was applied intraluminally in 1-microseconds pulses, which caused dilation of the arteries if hemoglobin was present in the lumen at sufficient concentration. Induced vasodilation did not specifically require the presence of hemoglobin; the same phenomenon could be repeated using an inert dye such as Evans blue as an optical absorber of laser energy. The optical density of the absorber, the number of applied laser pulses, and total amount of applied energy directly influenced the vasodilatory response. Laser-induced vasodilation was possible in both normal vessels and vessels denuded of endothelium. Pulsed-dye laser-induced vasodilation is therefore not a phenomenon mediated through chemical processes, but is rather a purely physical process initiated by the optical absorption of laser energy by the intraluminal medium, which probably induces cavitation bubble formation and collapse, resulting in the vasodilatory response of the vessel.

Animals↗
PubMed1995

Treatment of cafe au lait macules with lasers. A clinicopathologic correlation.

BACKGROUND: Cafe au lait macules (CALMs) respond variably to treatment with different lasers. This study was done to determine whether the type of laser and the individual histologic features of the CALMs could predict clinical response to treatment. Nine CALMs were treated with both the frequency-doubled Q-switched neodymium: YAG laser (wavelength, 532 nm; beam diameter, 2.0 mm) and the Q-switched ruby laser (wavelength, 694 nm; beam diameter, 5.0 mm). Both lasers were used at a fluence of 6.0 J/cm2. Biopsy specimens of the CALMs were obtained before and after treatment. Clinical follow-up was done at 1-, 3-, and 6-month intervals. OBSERVATIONS: Both lasers yielded variable responses to treatment. Two histologic subtypes of CALMs were identified, but these different subtypes did not predict clinical outcome after laser treatment. CONCLUSIONS: Cafe au lait macules respond variably to treatment with both the Q-switched ruby laser and the frequency-doubled Q-switched neodymium:YAG laser. Further research might address the effect of using multiple treatments. In view of these results, clinicians using lasers to treat CALMs should inform their patients of the potential for recurrence or darkening of CALMs.

Adult↗
PubMed1994

Comparative study of different laser systems.

OBJECTIVE: To review lasers, laser physics, laser-tissue interaction, delivery systems, and their clinical applications relevant to gynecology. SETTINGS: Gynecological Service at Massachusetts General Hospital (MGH) and MGH Laser Center. INTERVENTIONS: None. DESIGN: Laser literature review and personal experiences of the authors were used to prepare this manuscript. CONCLUSIONS: Lasers have been used in gynecologic practice for cutting and coagulating purposes. Photodynamic therapy has been used clinically for malignant conditions and is being investigated for dysplastic lesions of the lower genital tract and for endometrial ablation. Laser welding has potential, but further work is required in this field before it finds a clinical application. The main lasers used in gynecology are CO2, neodymium-yttrium aluminum garnet (Nd:YAG), and potassium tatanyl-phosphate-doubled Nd:YAG. Pulsed Ho:YAG laser looks promising, as does diode lasers. Holmium-yttrium aluminum garnet and diode lasers will be soon available commercially. Improvements in delivery systems have increased user friendliness, and more developments in this area are anticipated, for example, a fiber-optic delivery system for CO2 lasers. We believe that enhanced understanding of laser technology will provide unique applications for development in gynecology.

Female↗
PubMed1994

Treatment of nevus of Ota by Q-switched ruby laser.

BACKGROUND: There are few reports on therapy for nevus of Ota. Moreover, traditional treatments are largely palliative or risk permanent pigmentary changes and/or scarring. OBJECTIVE: The efficacy of the Q-switched ruby laser (694 nm, 40 nsec) as a therapy for nevus of Ota was investigated. METHODS: Nine nevi or portions thereof were irradiated up to six times with 4.5 and/or 7.5 J/cm2 at a mean exposure interval of 3 weeks. Sequential skin biopsy specimens were processed for light microscopy, immunohistochemistry, and electron microscopy. RESULTS: Cosmetic improvement occurred at both doses in the irradiated parts of the six nevi available for follow-up. No appreciable difference was noted between single and multiple treatments. There was no gross scarring. Light microscopy revealed dose-related immediate injury with more melanophages and fewer dermal melanocytes after irradiation in comparison with control areas. Electron microscopic distinction between dermal melanocytes and melanin-laden macrophages was difficult. A monoclonal antibody to human melanosome-specific antigen type 1 (HMSA-1) was used to distinguish between the two cell populations. CONCLUSION: Our findings suggest that the Q-switched ruby laser is useful for treating nevus of Ota.

Adult↗
PubMed1994

Thyroxine secretion rates during pregnancy in the rat.

Thyroxine secretion rates (TSR) at various stages of pregnancy in rats were measured by the radiothyroxine pool-turnover method. Groups of rats included normal controls (non-pregnant), days 5, 10, 20, and 22 of pregnancy and near term (within 24 hours prior to parturition if past 22 days of pregnancy). Each animal had blood samples taken just prior to injection of 10 microCi L-thyroxine (L-T4)-131I and at 12, 24, 36, and 48 hours afterwards. Determinations of thyroxine iodine (T4-I), volume of distribution (VD), fractional turnover rate (K), and L-T4 pool size were made from these samples. TSR was calculated as the product of (1.54) (T4-I) (VD) (K). An increase in TSR occurred near term, 3.65 micrograms L-T4/day compared to 1.23 micrograms L-T4/day in the controls, was primarily due to an increase in VD from 33.9 ml in the controls to 90.0 ml near term. A rapid increase in TSR to 3.65 micrograms L-T4/day just prior to term was postulated to be due to a stimulatory action of relaxin in the presence of estrogen upon L-T4 utilization. The mechanism of the increase in TSR in pregnant rats is probably due to the effect of several hormonal changes in maternal tissues throughout pregnancy and to adaptation of the pregnant animals to higher metabolic needs of the rapid developing fetuses.

Animals↗
PubMed1994

Pulsed photothermal radiometry in optically transparent media containing discrete optical absorbers.

A description of heat transport by conduction and radiation in inhomogeneous materials following absorption of a brief optical pulse is presented, and investigated experimentally using pulsed photothermal radiometry (PPTR). The model indicates that the role of radiation as an intramedium heat transfer modality increases with increasing temperatures and decreasing infrared (IR) absorption of the medium. However, for the range of conditions analysed in this study, conductive transfer dominates. Thus, the inclusion of radiation does not significantly perturb the internal temperature profiles, although it does influence the radiometric emission from the sample, and hence the PPTR signal. The thermal confinement effects described in this study may be relevant in photomedicine, for example in pulsed laser irradiation of tissues containing small absorbing targets.

Algorithms↗
PubMed1994

Ineffective treatment of refractory melasma and postinflammatory hyperpigmentation by Q-switched ruby laser.

BACKGROUND: Melasma and postinflammatory pigmentation are cosmetic problems with limited options for treatment. OBJECTIVE: To determine whether selective photothermolysis of pigmented cells by Q-switched ruby laser treatment would produce clinical benefit in these disorders. METHODS: Eight subjects with melasma or postinflammatory hyperpigmentation refractory to traditional treatments were treated with Q-switched ruby laser pulses (694 nm, 40 nanoseconds) at fluences of 15-7.5 J/cm2, and followed. Histology was obtained before and after treatment. RESULTS: Regardless of fluence, no permanent improvement and, in some cases, darkening was seen in each type of lesion. Except for small depression at high fluences in black patients, there were no textural changes after healing. Immediately after treatment, there was epidermal and dermal injury, with extracellular melanin. Several months later, epidermal pigmentation had returned to baseline and dermal macrophages were apparently focally increased. CONCLUSIONS: The Q-switched ruby laser by itself does not provide an effective treatment for refractory melasma or postinflammatory hyperpigmentation.

Adult↗
PubMed1994

Optical and thermal characterization of natural (Sepia officinalis) melanin.

The optical properties and the thermal diffusivity of natural cuttlefish (Sepia officinalis) melanin have been measured. The optical absorption and scattering properties of melanin particles were determined at 580 nm and 633 nm, using photometric and photothermal techniques. For the photometric studies, the absorption and the transport scattering coefficients were determined from the measurements of diffuse reflectance and transmittance. The scattering anisotropy was obtained from an additional measurement of the total attenuation coefficient and independently obtained by goniometry. For photothermal studies, pulsed photothermal radiometry was used to deduce the absorption and transport scattering coefficients via a model based on optical diffusion theory. Pulsed photothermal radiometry was also used to provide the thermal diffusivity of solid melanin pressed pellets.

Animals↗
PubMed1994

Treatment of epidermal pigmented lesions with the frequency-doubled Q-switched Nd:YAG laser. A controlled, single-impact, dose-response, multicenter trial.

BACKGROUND AND DESIGN: The removal of benign, aesthetically important, pigmented lesions can be effectively treated with multiple modalities. Selective removal of the pigment by lasers is becoming increasingly popular. A three-center trial evaluated the effectiveness of the frequency-doubled Q-switched neodymium (Nd):YAG laser (532 nm, 2.0-mm spot size, 10 nanoseconds) in removing benign epidermal pigmented lesions with a single treatment. Forty-nine patients were treated for multiple lentigines (n = 37), for cafe au lait macules (n = 7), and for miscellaneous lesions (n = 5). Treatment areas were divided into four quadrants, irradiated with fluences of 2, 3, 4, or 5 J/cm2 and evaluated at 1- and 3-month intervals following treatment. RESULTS: For lentigines, response was related to dose with a greater than 75% pigment removal achieved in 60% of those lesions treated at higher energy fluences. Responses were more variable with other lesions, with fair-to-good improvement noted in most cases. Mild, transient erythema; hypopigmentation; and hyperpigmentation were noted in several patients, but resolved spontaneously within 3 months. No other textural changes, scarring, or other side effects were noted. CONCLUSION: The frequency-doubled Q-switched Nd: YAG laser (532 nm) safely and effectively treats benign epidermal pigmented lesions.

Adult↗
PubMed1993

Cosmetic tattoo ink darkening. A complication of Q-switched and pulsed-laser treatment.

BACKGROUND: High-energy, short-pulse lasers, eg, Q-switched lasers, emitting visible and near-infrared light have recently been developed for removing tattoos, with little risk of scarring. The mechanisms of action, and possible adverse effects other than scarring and hypopigmentation, are not fully understood. OBSERVATIONS: We describe five cases of pulsed-laser-induced, immediate, irreversible darkening of cosmetic, white, flesh (skin-color), and pink-red colored tattoos. Irreversible ink darkening can be an insidious complication, because immediate whitening of the skin temporarily obscures the subsequently impressive color change. Among these cases, irreversible ink darkening occurred with Q-switched ruby (694 nm), Q-switched neodymium (Nd):YAG (1064 nm/532 nm), and pulsed green dye (510 nm) lasers. Attempts to remove the darkened ink with further laser treatment failed in two cases, and surgical excision was necessary. In the other three cases, subsequent laser treatments successfully removed the darkened ink. The red cosmetic tattoo ink used in one of the cases was placed in agar in vitro and was converted to a black compound immediately on Q-switched ruby laser exposure. Ferric oxide, a brown-red ingredient commonly used in cosmetic tattoos, was similarly tested and blackened in vitro by Q-switched ruby laser exposures. CONCLUSIONS: Although most tattoos are not darkened by laser treatment, short-pulsed lasers over a wide spectrum can cause immediate darkening of some tattoo inks. Patients should be warned of the potential for irreversible cosmetic tattoo darkening, and test-site exposures should be performed prior to treatment. In some cases, subsequent laser treatments may remove the blackened ink. The mechanism probably involves, at least for some tattoos, reduction of ferric oxide (Fe2O3, "rust") to ferrous oxide (FeO, jet black), but the chemical reaction that is involved remains unknown.

Adult↗
PubMed1993

Injury and adhesion formation following ovarian wedge resection with different thermal surgical modalities.

The purpose of this study is to determine the role of bleeding, acute thermal damage, and charring in adhesion formation. Postoperative adhesions were compared following ovarian wedge resection in 48 rabbits using different lasers, electrosurgery, and scalpel. Twelve ovaries were sectioned per modality, in randomized pairs. Acute thermal injury as assessed by histology, bleeding, and charring differed among the modalities used. Adhesions were assessed 4 weeks later, by an investigator completely blinded of the treatment protocol. The adhesion scores were 11.6 +/- 8.0 with pulsed Er:YAG laser; 11.9 +/- 7.5 with scalpel; 8.3 +/- 9.3 with electrocautery; 6.7 +/- 8.8 with a continuous (c.w.) Nd:YAG laser; 5.3 +/- 4.8 with c.w. CO2 laser; 3.1 +/- 2.7 with pulsed CO2 laser; 1.7 +/- 1.8 with pulsed Ho:YAG laser; and 0.8 +/- 1.5 in the control (no resection) group. Ho:YAG, Nd:YAG, and electrocautery were completely hemostatic. Bleeding was minimal with the CO2 lasers. Er:YAG and scalpel caused maximum bleeding, requiring hemostatic measures to prevent exsanguination. Charring occurred with electrocautery, CO2 laser, and Nd:YAG laser. Bleeding and charring correlated with adhesion formation, but the histological depth of thermal damage did not. The Ho:YAG laser is a hemostatic, fiber-optic compatible laser causing significantly fewer adhesions (P < 0.04) than scalpel, electrocautery, Nd:YAG, Er:YAG, and c.w. CO2 lasers. Clinical use of the Ho:YAG laser, and the role of carbonization in promoting adhesions, deserve further study.

Adnexal Diseases↗
PubMed1993

Culicoides (Diptera: Ceratopogonidae) associated with white-tailed deer habitat and livestock operations in the northern Great Plains.

Twelve Culicoides species were collected from white-tailed deer habitat and cattle operations in the Northern Great Plains as part of an ongoing study of the geographical distribution and seasonal occurrence of C. variipennis and other species in North Dakota. C. variipennis, C. obsoletus, and C. stellifer were collected in both western and eastern counties. C. arboricola, C. hinmani, C. nanus, and C. palmerae are reported for the first time from North Dakota.

Animals↗