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Biomedical subjects

R R Anderson

Publications and source records attributed to R R Anderson.

At least 55 records · Page 3Linked to original sources
PubMed1999

Optical hair removal.

Traditional methods of hair removal have proven unsatisfactory for many individuals with excessive or unwanted hair. In the last few years, several lasers and xenon flashlamps have been developed that promise to fulfill the need for a practical, safe, and long-lasting method of hair removal. Aggressive marketing of these has contributed to their popularity among patients and physicians. However, significant controversy and confusion surrounds this field. This article provides a detailed explanation of the scientific underpinnings for optical hair removal and explores the advantages and disadvantages of the various devices currently available (Nd:YAG, ruby, alexandrite, diode lasers, and xenon flashlamp). Treatment and safety guidelines are provided to assist the practitioner in the use of these devices. Although the field of optical hair removal is still in its infancy, initial reports of long-term efficacy are encouraging.

Adult↗
PubMed1999

In vivo confocal scanning laser microscopy of human skin II: advances in instrumentation and comparison with histology.

In 1995, we reported the construction of a video-rate scanning laser confocal microscope for imaging human skin in vivo. Since then, we have improved the resolution, contrast, depth of imaging, and field of view. Confocal images of human skin are shown with experimentally measured lateral resolution 0.5-1.0 microm and axial resolution (section thickness) 3-5 microm at near-infrared wavelengths of 830 nm and 1064 nm; this resolution compares well to that of histology which is based on typically 5 microm thin sections. Imaging is possible to maximum depth of 350 microm over field of view of 160-800 microm. A mechanical skin-contact device was developed to laterally stabilize the imaging site to within +/- 25 microm in the presence of subject motion. Based on these results, we built a small, portable, and robust confocal microscope that is capable of imaging normal and abnormal skin morphology and dynamic processes in vivo, in both laboratory and clinical settings. We report advances in confocal microscope instrumentation and methods, an optimum range of parameters, improved images of normal human skin, and comparison of confocal images with histology.

Epidermis↗
PubMed1999

A pilot study of in vivo immediate tissue contraction with CO2 skin laser resurfacing in a live farm pig.

BACKGROUND: It has been suggested that tissue ablation, collagen shrinkage, and new collagen deposition contribute to the clinical outcome of laser skin resurfacing. OBJECTIVE: To study the effects of fluence and pass number on thermal damage and tissue shrinkage, we performed experiments in an in vivo farm pig model. METHODS: A CO2 laser was used to treat the flank skin of a farm pig. There were nine treatment sites based on number of passes and fluence per pass. Wound surface areas were measured pretreatment and immediately posttreatment. Biopsies were performed immediately after irradiation. RESULTS: Surface area measurements showed that immediate contraction tended to increase with increasing fluence and pass number up to a maximum of approximately 38% shrinkage, after which the percent contraction remained constant. Thermal damage increased with pass number for low and moderate fluence groups; however, in high fluence groups the thermal damage remained constant with an increasing number of passes. CONCLUSIONS: Our results suggest that CO2 laser resurfacing produces immediate tissue contraction and residual thermal damage that is saturable for multiple passes and high fluences. For small fluences, however, there is an almost linear increase in thermal damage and shrinkage with an increasing number of passes.

Animals↗
PubMed1999

Contact cooling of the skin.

Skin precooling can be used to reduce epidermal thermal damage in laser procedures (such as hair removal) where the target structures are located up to several millimetres below the skin surface. We have developed and experimentally verified a computational model that describes contact precooling of a multilayered skin structure prior to laser irradiation. The skin surface is assumed to be brought into thermal contact with a cold plate made of material with a high thermal conductivity. The approximate analytical solution for the skin temperature is obtained by considering the plate as a local heat sink. The time evolution of temperature (in both the skin and the plate) is simulated numerically to yield the optimal cooling parameters. To experimentally verify the numerical results of the model, we performed direct measurements of skin temperature for contact cooling with a sapphire plate held at several different temperatures in the range +10 to -30 degrees C.

Aluminum Oxide↗
PubMed1999

Noninvasive imaging of human oral mucosa in vivo by confocal reflectance microscopy.

OBJECTIVES/HYPOTHESIS: To study the microscopic anatomy of normal oral tissues in vivo using confocal reflectance microscopy (CRM). This novel and noninvasive imaging modality can define and characterize healthy oral mucosa and thus this work serves as the foundation for studying oral diseases in vivo. STUDY DESIGN: This was a pilot observational cohort study comparing noninvasive CRM images with histology. MATERIALS AND METHODS: Lip and tongue mucosa were imaged by CRM in six healthy human subjects. In CRM living tissue is illuminated by a laser source and backscattered (or reflected) light is collected by a detector. Image contrast is determined by natural differences in refractive indices of organelles and other subcellular structures within the tissues. Gray-scale images were displayed in real-time on a video monitor and represented horizontal (en face) optical sections through the tissue. Motion of the oral tissue relative to the objective lens was minimized with a tissue stabilizer. After imaging, biopsies were taken from the same site of lip mucosa to correlate noninvasive confocal images with conventional histology. RESULTS: Confocal images correlated well with conventional histology, both qualitatively (visual analysis) and quantitatively (stereology). Imaging was possible up to depths of 490 and 250 microm in the lip and tongue, respectively. Cells and organelles including nuclei, circulating blood cells, and extracellular matrix were clearly observed. CONCLUSION: CRM provides details of normal human oral mucosa at the cellular level without the artifacts of histological processing, and thus has the potential for further development and use in clinical practice as a diagnostic tool for the early detection of oral cancer and precancer.

Adult↗
PubMed1999

In vivo abnormal keratinazation in Darier-White's disease as viewed by real-time confocal imaging.

Darier-White's disease is a rare autosomal-dominant disorder of keratinization. The underlying pathology for the clinical presentation is acantholysis, and various types of dyskeratosis and acanthosis. In this study, we utilized a non-invasive optical imaging modality, confocal reflectance microscopy, to identify specific histologic features of Darier-White's disease in vivo. Micrographic findings in the confocal images were corps ronds, suprabasal clefts, acantholytic suprabasal keratinocytes, and villi. Real-time confocal images are illustrative and can be well correlated with known light microscopic phenomena, particularly in the case of keratinization abnormalities in Darier-White's disease.

Darier Disease↗
PubMed1999

Confocal reflectance imaging of folliculitis in vivo: correlation with routine histology.

Near-infrared confocal reflectance microscopy (CM) is a high-resolution: non-invasive imaging technique with promising future in dermatology. A pustular lesion from a 35-year-old male with a known history of folliculitis was non-invasively viewed with CM and later biopsied. Optical sections were correlated with routine histology. This optical technique allows us to view non-invasively transverse skin sections to a controlled depth in real time. In the CM images, tissue can be visualize with cellular and subcellular detail as shown by imaging infiltrating neutrophils (PMNs) within the subcorneal pustule of a superficial folliculitis in vivo.

Adult↗
PubMed1999

Characterization of psoriasis in vivo by reflectance confocal microscopy.

Among available non-invasive imaging tools, confocal reflectance microscopy (CM) provides the highest-resolution optical sectioning of skin in vivo, to a controlled depth of 200-350 microns, the level of the upper reticular dermis. In this study, CM was used to view the histological features of psoriasis in vivo in lesional and non-lesional skin of five patients with stable psoriasis vulgaris. Stereohistological analysis of non-invasive confocal sections, and the correlation with transverse (en face) hematoxylin- and eosin-stained sections from biopsies, was also performed. In psoriatic lesions, nucleated corneocytes and collections of infiltrating inflammatory cells were clearly seen. Morphometric parameters such as epidermal height, length of papillary dermis, and the count of dermal papillae were also easily quantified. In the upper dermis, dilated capillary loops were always present. Since CM sections are en face, the presence or absence of the granular layer could not be visualized in single frames, but could be monitored in a sequence of real-time videotaped images. In summary, CM provides a new technique for histologically evaluating psoriasis in vivo.

Adult↗
PubMed1998

Comparative clinical trial of 2 carbon dioxide resurfacing lasers with varying pulse durations. 100 microseconds vs 1 millisecond.

OBJECTIVES: To compare the clinical and histological effects of 2 carbon dioxide lasers with different pulse durations and to evaluate the effect of carbon dioxide laser pulse duration on postprocedure erythema, wound healing, and efficacy of wrinkle treatment. DESIGN: Prospective, randomized, comparative clinical trial. SETTING: A university-affiliated hospital-based laser center. PATIENTS: Thirty-five patients with facial wrinkles were enrolled in the study. Treatment sites included 15 perioral, 14 periorbital areas, and 6 full face. INTERVENTION: A 2-sided comparison was performed. One side of the study site was treated with the TruPulse laser (Tissue Technologies, Palomar Medical Products Inc, Lexington, Mass). The other side of the study site was treated with the UltraPulse 5000 laser (Coherent Medical Inc, Palo Alto, Calif). The 2 sides were treated to equivalent tissue effects rather than maintaining the number of passes. MAIN OUTCOME MEASURES: Photographs of the treatment areas at baseline, week 1, week 2, month 2, and month 6 were evaluated by a 5-member panel for degree of erythema, amount of edema, and percentage of wrinkle improvement. Silicon skin casts for profilometry measurements before and after the treatment were compared. To evaluate skin shrinkage, surface area before and after treatment of square tattoos on both cheeks of the full-face patients were computed using a digital imaging system. Histological sections before and after the procedure were analyzed. RESULTS: At week 1, 75% of the patients had more erythema on the UltraPulse than TruPulse sides. The difference in erythema (TruPulse less than UltraPulse) between the 2 treatment sides was clinically mild yet statistically significant for weeks 1 (P = .05) and 2 (P = .05). Although observed results favored the UltraPulse over the TruPulse, the difference in efficacy between the 2 lasers did not reach statistical significance. CONCLUSIONS: Compared with the longer pulse-duration carbon dioxide laser, the shorter pulse-duration carbon dioxide laser, used with higher energy and more passes, caused slightly less erythema while maintaining efficacy. The longer pulse-duration laser required lower energy and fewer number of passes to achieve an equivalent depth of ablation, level of residual thermal damage, and degree of efficacy. The shorter TruPulse allows for more superficial tissue damage per pass and therefore is best suited for situations requiring superficial or more controlled ablation. The longer UltraPulse achieves a desirable depth of tissue damage with fewer passes. The data did not support the long-term presence of tissue collagen shrinkage in the treated areas.

Adult↗
PubMed1998

Comparison of responses of tattoos to picosecond and nanosecond Q-switched neodymium: YAG lasers.

OBJECTIVE: To test the hypothesis that picosecond laser pulses are more effective than nanosecond domain pulses in clearing of tattoos. DESIGN: Intratattoo comparison trial of 2 laser treatment modalities. SETTING: A large interdisciplinary biomedical laser laboratory on the campus of a tertiary medical center. PATIENTS: Consecutive patients with black tattoos were enrolled; all 16 patients completed the study. INTERVENTION: We treated designated parts of the same tattoo with 35-picosecond and 10-nanosecond pulses from 2 neodymium:YAG lasers. Patients received a total of 4 treatments at 4-week intervals. All laser pulse parameters were held constant except pulse duration. Radiation exposure was 0.65 J/cm2 at the skin surface. Biopsies were performed for routine microscopic and electron microscopic analysis at the initial treatment session and 4 weeks after the final treatment in 8 consenting patients. Also, ink samples were irradiated in vitro. MAIN OUTCOME MEASURES: In vivo, on the completion of treatment, a panel of dermatologists not associated with the study (and blinded to the treatment type) evaluated photographs to assess tattoo lightening. Formalin-fixed specimens were examined for qualitative epidermal and dermal changes as well as depth of pigment alteration. Electron micrographs were examined for particle electron density and size changes (in vivo and in vitro). The gross in vitro optical density changes were measured. RESULTS: In 12 of 16 tattoos, there was significant lightening in the picosecond-treated areas compared with those treated with nanosecond pulses. Mean depth of pigment alteration was greater for picosecond pulses, but the difference was not significant. In vivo biopsy specimens showed similar electron-lucent changes for both pulse durations. In vitro results were similar for both pulse durations, showing increases in particle sizes and decreased electron density as well as gross ink lightening. CONCLUSIONS: Picosecond pulses are more efficient than nanosecond pulses in clearing black tattoos. Black tattoos clear principally by laser-induced changes in the intrinsic optical properties of the ink.

Aluminum Silicates↗
PubMed1998

Permanent hair removal by normal-mode ruby laser.

OBJECTIVE: To assess the permanence of hair removal by normal-mode ruby laser treatment. METHODS: Hair removal was measured for 2 years after a single treatment with normal-mode ruby laser pulses (694 nm, 270 microseconds, 6-mm beam diameter). OBSERVATIONS: Six test areas on the thighs or backs of 13 volunteers were exposed to normal-mode ruby laser pulses at fluences of 30 to 60 J/cm2 delivered to both shaved and wax-epilated skin. In addition, there was a shaved and wax-epilated control site. Terminal hairs were manually counted before and after laser exposure. Transient alopecia occurred in all 13 participants after laser exposure, consistent with induction of telogen. Two years after laser exposure, 4 participants still had obvious, significant hair loss at all laser-treated sites compared with the unexposed shaved and wax-epilated control sites. In all 4 participants, there was no significant change in hair counts 6 months, 1 year, and 2 years after laser exposure. Laser-induced alopecia correlated histologically with miniaturized, velluslike hair follicles. No scarring and no permanent pigmentary changes were observed. CONCLUSIONS: Permanent, nonscarring alopecia can be induced by a single treatment with high-fluence ruby laser pulses. Miniaturization of the terminal hair follicles seems to account for this response.

Alopecia↗
PubMed1998

CO2 laser resurfacing of psoriatic plaques: a pilot study.

BACKGROUND AND OBJECTIVE: Laser resurfacing can precisely remove epidermis and papillary dermis, sites pivotal to the pathogenesis of psoriasis. Our objective was to determine the efficacy and safety of superficially ablating carbon dioxide (CO2) lasers for treating isolated, recalcitrant psoriatic plaques. MATERIALS AND METHODS: Twelve adult subjects with stable, plaque-type psoriasis were recruited. In six volunteers, the quadrants received different numbers of passes with a 60 microsec pulsed CO2 (Tru-Pulse) laser. In the remaining patients, one quadrant underwent curettage prior to resurfacing, the second resurfacing with a scanned continuous wave (Sharplan Silktouch) CO2 laser and the last curettage alone. RESULTS: Despite clinical and histological evidence of complete ablation of the epidermis and papillary dermis, most quadrants recurred within 8 weeks. Surprisingly, two patients showed no recurrence after 4 months. CONCLUSION: Ablation of the entire epidermis and papillary dermis with either pulsed or scanned CO2 lasers appears generally ineffective in treating recalcitrant psoriatic plaques, although the clearing seen in two patients suggests potentially successful future research directions.

Adolescent↗
PubMed1998

Hair growth cycle affects hair follicle destruction by ruby laser pulses.

It has been shown that normal mode ruby laser pulses (694 nm) are effective in selectively destroying brown or black pigmented hair follicles in adult Caucasians. This study investigated how the various stages of the hair follicle growth cycle influence follicle destruction by ruby laser treatment, using a model of predictable synchronous hair growth cycles in the infantile and adolescent mice. A range of ruby laser pulse fluences was delivered during different stages of the hair growth cycle, followed by histologic and gross observations of the injury and regrowth of hair. Actively growing and pigmented anagen stage hair follicles were sensitive to hair removal by normal mode ruby laser exposure, whereas catagen and telogen stage hair follicles were resistant to laser irradiation. Selective thermal injury to follicles was observed histologically, and hair regrowth was fluence dependent. In animals exposed during anagen, intermediate fluences induced nonscarring alopecia, whereas high fluences induced scarring alopecia. The findings of this study suggest treatment strategies for optimal laser hair removal.

Alopecia↗
PubMed1998

Endogenous skin fluorescence includes bands that may serve as quantitative markers of aging and photoaging.

Aging and photoaging cause distinct changes in skin cells and extracellular matrix. Changes in hairless mouse skin as a function of age and chronic UVB exposure were investigated by fluorescence excitation spectroscopy. Fluorescence excitation spectra were measured in vivo, on heat-separated epidermis and dermis, and on extracts of mouse skin to characterize the absorption spectra of the emitting chromophores. Fluorescence excitation spectra obtained in vivo on 6 wk old mouse skin had maxima at 295, 340, and 360 nm; the 295 nm band was the dominant band. Using heat separated tissue, the 295 nm band predominantly originated in the epidermis and the bands at 340 and 360 nm originated in the dermis. The 295 nm band was assigned to tryptophan fluorescence, the 340 nm band to pepsin digestable collagen cross-links fluorescence and the 360 nm band to collagenase digestable collagen cross-links fluorescence. Fluorescence excitation maxima remained unchanged in chronologically aged mice (34-38 wk old), whereas the 295 nm band decreased in intensity with age and the 340 nm band increased in intensity with age. In contrast, fluorescence excitation spectra of chronically UVB exposed mice showed a large increase in the 295 nm band compared with age-matched controls and the bands at 340 and 350 nm were no longer distinct. Two new bands appeared in the chronically exposed mice at 270 nm and at 305 nm. These reproducible changes in skin autofluorescence suggest that aging causes predictable alterations in both epidermal and dermal fluorescence, whereas chronic UV exposure induces the appearance of new fluorphores.

Animals↗
PubMed1998

Genetic counseling: clinical and ethical challenges.

After explaining the origin, nature, and goals of genetic counseling, we consider the impact of the Human Genome Project on its practice. In light of the availability of presymptomatic tests for late-onset disorders and the possibility of preventive behavior or treatment, we examine the apparent conflict between nondirectiveness and directiveness in genetic counseling. We discuss views of genetic counselors, medical geneticists, and counselees on specific issues, and document gender differences in attitudes toward genetic ties to offspring. Because genetic discrimination and unequal access to genetic services are likely to increase with advances in genetics, we conclude that efforts of genetic counselors to adhere to the principle of justice or equity in their practice cannot be successful without governmental and public support, as well as support from researchers and colleagues in health care.

Ethics, Medical↗
PubMed1998

Protoporphyrin IX fluorescence induced in basal cell carcinoma by oral delta-aminolevulinic acid.

Limited depth of penetration significantly limits photodynamic therapy of nodular basal cell carcinoma (BCC) using topical delta (5)-aminolevulinic acid (ALA). To demonstrate safety and efficacy of orally administered ALA in inducing endogenous protoporphyrin IX (PpIX) production in BCC, 13 patients with BCC ingested ALA in a dose-escalation protocol. All dose ranges (10, 20 or 40 mg/kg single doses) resulted in formation of PpIX in human skin and BCC, measurable by in vivo fluorescence spectrophotometry. The PpIX fluorescence peaked in tumors before normal adjacent skin from 1 to 3 h after ALA ingestion. Gross fluorescence imaging of ex vivo specimens revealed greater PpIX fluorescence in tumor than normal skin only at the 40 mg/kg dose. Fluorescence microscopy confirmed this finding by showing distinct, full-thickness PpIX fluorescence in all subtypes of BCC only after ALA given at 40 mg/kg. Side effects were dose dependent and self limited. Photosensitivity lasting less than 24 h and nausea coinciding with peak skin PpIX fluorescence occurred at 20 and 40 mg/kg doses. After 40 mg/kg ALA, serum hepatic enzyme levels rose to a maximum within 24 h, then resolved over 1-3 weeks. Transient bilirubinuria occurred in two patients.

Administration, Oral↗