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Biomedical subjects

J S Dover

Publications and source records attributed to J S Dover.

105 records · Page 6Linked to original sources
PubMed1988

Low-fluence carbon dioxide laser irradiation of lentigines.

Low-fluence carbon dioxide (CO2) laser irradiation of skin has previously been shown to induce damage limited primarily to the epidermis. To evaluate whether this technique was therapeutically effective for pigmented epidermal lesions, ten lentigines caused by methoxsalen and ultraviolet light therapy were treated in one patient using the CO2 laser at fluences ranging from 3.0 to 7.7 J/cm2 for 0.1-s exposures with 4.5-mm spot size. Based on substantial clearing in seven of ten lesions treated, 146 solar lentigines were treated in five patients at fluences of 3.0, 3.7, or 4.4 J/cm2. Biopsies were performed on a total of 30 lesions immediately and 24 hours, seven days, and six weeks after irradiation. Of 125 lesions followed up clinically for six weeks, 12 cleared completely, 81 lightened substantially, and 28 remained unchanged. Only two demonstrated atrophic change. Hyperpigmentation or hypopigmentation did not occur. All lesions that improved had been treated at 3.7 or 4.4 J/cm2. Immediate histologic injury consisted of vacuolar and spindly change and subsequent vesiculation limited to the basilar epidermis. Twenty-four hours later there was epidermal necrosis with regeneration, 0.1 mm of dermal basophilia and stromal condensation, and a mild inflammatory infiltrate. These alterations were dose-dependent, with near complete epidermal necrosis and superficial dermal involvement at the highest fluence, and only focal epidermal necrosis at the lowest. At seven days, epidermal regeneration was complete with traces of melanin remaining in keratinocytes. Melanophages first appeared at seven days and persisted at six weeks, by which time the inflammatory infiltrate had cleared. No lentiginous proliferation was evident and epidermal pigmentation had become normal. Low-fluence CO2 laser irradiation is an effective means of damaging the epidermis with only minimal dermal change. This mode of therapy is an effective way to lighten the pigmentation of lentigines without substantial scarring.

Adult↗
PubMed1987

Melanosomes are a primary target of Q-switched ruby laser irradiation in guinea pig skin.

The specific targeting of melanosomes may allow for laser therapy of pigmented cutaneous lesions. The mechanism of selective destruction of pigmented cells by various lasers, however, has not been fully clarified. Black, brown, and albino guinea pigs were exposed to optical pulses at various radiant exposure doses from a Q-switched, 40 nsec, 694 nm ruby laser. Biopsies were analyzed by light and electron microscopy (EM). Albino animals failed to develop clinical or microscopic evidence of cutaneous injury after irradiation. In both black and brown animals, the clinical threshold for gross change was 0.4 J/cm2, which produced an ash-white spot. By light microscopy, alterations appeared at 0.3 J/cm2 and included separation at the dermoepidermal junction, and the formation of vacuolated epidermal cells with a peripheral cytoplasmic condensation of pigment. By EM, enlarged melanosomes with a central lucent zone were observed within affected epidermal cells at 0.3 J/cm2. At 0.8 and 1.2 J/cm2, individual melanosomes were more intensely damaged and disruption of melanosomes deep in the hair papillae was observed. Dermal-epidermal blisters were formed precisely at the lamina lucida, leaving basal cell membranes and hemidesmosomes intact. Possible mechanisms for melanosomal injury are discussed. These observations show that the effects of the Q-switched ruby laser are melanin-specific and melanin-dependent, and may be useful in the selective destruction of pigmented as well as superficial cutaneous lesions.

Animals↗
PubMed1986

Release of prostaglandin D2 and histamine in a case of localized heat urticaria, and effect of treatments.

A case of localized heat urticaria in a 70-year-old woman is reported. Increased plasma levels of prostaglandin D2 and blood histamine after heat challenge indicate a role for mast cell degranulation in the pathophysiology of the syndrome. Treatment with astemizole increased the temperature threshold to wealing, but not to itch or erythema. The patient was partially desensitized by repeated exposure to heat and this was further improved by indomethacin. After treatment there was no increase in plasma prostaglandin D2 on challenge. No evidence was found for the activation of the alternative complement pathway.

Aged↗
PubMed1986

Disseminated superficial actinic porokeratosis. Coexistence with other porokeratotic variants.

The coexistence of disseminated superficial actinic porokeratosis (DSAP) with other variants of porokeratosis is rare. We report three such cases: DSAP with porokeratosis of Mibelli; DSAP with linear porokeratosis; and DSAP occurring in the mother of a girl with linear porokeratosis. Although different areas of skin and different family members usually express the same morphological variant, we suggest that the simultaneous expression of two closely linked gene loci could explain the coexistence of different porokeratotic variants.

Adolescent↗
PubMedDate not supplied

Nonablative laser and light therapy: an approach to patient and device selection.

Nonablative laser and light therapy is a relatively novel modality for the improvement of the visual appearance of photodamaged, scarred, and injured skin. A number of different wavelengths and devices have been purported to be efficacious for the delivery of nonablative therapy. Among the features that can be addressed are red spots and telangiectasia, pigmentation and lentigines, and their daily routines while benefiting from the cumulative effects of skin rejuvenation.

Cosmetic Techniques↗
PubMedDate not supplied

Treatment of photoaging with topical aminolevulinic acid and light.

Photodynamic therapy (PDT) has been used for several years for the treatment of actinic keratoses and prevention of invasive nonmelanoma cancers. More recently, increasing physician expertise with the topical sensitizers and light sources employed in PDT has led to expanded applications, including its use for improvement of the visible signs of photoaging. Aesthetic treatment of photoaged skin with brief application of topical 5-aminolevulinic acid followed by well-tolerated light sources, such as intense pulsed light or pulsed-dye laser, can enhance the effectiveness of nonablative laser treatment without increasing adverse effects or downtime.

Administration, Topical↗
PubMedDate not supplied

Treatment of acne scarring.

Acne scarring is common but surprisingly difficult to treat. Scars can involve textural change in the superficial and deep dermis, and can also be associated with erythema, and less often, pigmentary change. In general, treatment of acne scarring is a multistep procedure. First, examination of the patient is necessary to classify the subtypes of scarring that are present. Then, the patient's primary concerns are elicited, and the patient is offered a menu of procedures that may address the various components of the scarring process. It is important to emphasize to the patient that acne scarring can be improved but never entirely reversed.

Acne Vulgaris↗