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J M Grevelink

Publications and source records attributed to J M Grevelink.

27 records · Page 2Linked to original sources
PubMed1996

Modulation of alpha 4 beta 1 and alpha 5 beta 1 integrin expression: heterogeneous effects of Q-switched ruby, Nd:YAG, and alexandrite lasers on melanoma cells in vitro.

BACKGROUND AND OBJECTIVE: Integrins of the beta 1 family are cellular adhesion molecules that play an important role in cell attachment and migration by interacting with extracellular matrix molecules. Agents such as hormones, cytokines, and ultraviolet radiation have all been shown to have an integrin modulating potential. The present study indicates that radiation of Q-switched lasers is also able to induce transient changes in integrin expression levels on human melanoma cells in vitro. STUDY DESIGN/MATERIALS AND METHODS: Radiation from Q-switched Ruby (694 nm), Alexandrite (755 nm), and Nd:YAG laser (1,064 nm) with fluences comparable to those that are generally used in treating dermatologic lesions were used to irradiate a subconfluent layer of human melanoma cells. After fixed time intervals, the cells were harvested either to analyse the integrin expression by flow cytometry or to investigate changes in cell attachment, spreading, and migration. RESULTS: It was established that all three types of laser were able to cause a significant downregulation of both the alpha 4 and the common beta 1 integrin subunit. The Alexandrite and Ruby lasers also induced a decrease in alpha 5 expression; however, the cells treated with the Nd:YAG laser showed a marked upregulation of the alpha 5 subunit. The expression of the other beta 1 integrin subunits was shown to be unaltered after laser treatment. Downregulation of the alpha 4 upregulation of the alpha 5 integrin subunit expression resulted in, respectively, decreased and increased attachment and spreading on fibronectin, the extracellular matrix ligand for both the alpha 4 beta 1 and alpha 5 beta 1 integrins. Marked upregulation of the alpha 5 subunit also resulted in a higher migration rate. CONCLUSION: Taken together, these results show that nonlethal doses of Q-switched laser radiation are able to induce changes in cellular behavior in vitro by modulating the integrin expression pattern.

Aluminum Oxide↗
PubMed1996

Laser treatment of tattoos in darkly pigmented patients: efficacy and side effects.

BACKGROUND: Many modalities for the treatment of tattoos and pigmented lesions produce a greater risk of complications in Fitzpatrick types V and VI skin because of an increased incidence of adverse pigmentary changes and keloidal scarring. In fair-skinned persons Q-switched lasers have proved effective in removing pigmented lesions and tattoos without scarring. OBJECTIVE: This study was conducted to determine the efficacy and effects of Q-switched lasers on a small series of darkly pigmented patients with tattoos. METHODS: Four patients of Ethiopian origin with facial and neck tribal tattoos were treated with both the Q-switched ruby and Nd:YAG lasers. One black woman with a multicolored tattoo on the mid chest was treated with the Q-switched ruby laser. RESULTS: Clearing of all lesions was seen. The treatments did not result in scarring or permanent pigment changes other than the ones intended. CONCLUSION: Our results indicate that in darkly pigmented patients, Q-switched laser treatment of tattoos can be performed successfully. The longer wavelength Q-switched Nd:YAG laser is recommended when removing tattoos in darker complected persons. A test treatment is advised before treatment of large skin areas.

Adult↗
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

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↗
PubMed1993

The Q-switched Nd:YAG laser effectively treats tattoos. A controlled, dose-response study.

BACKGROUND AND DESIGN: The Q-switched ruby laser was recently shown to remove tattoos without scarring. The Q-switched neodymium: yttrium aluminum garnet (Nd:YAG) laser, which targets black ink with a longer wavelength that has less absorption by melanin, should effectively treat tattoos with fewer pigmentary alterations. A prospective, blinded, controlled study was conducted to assess the ability of the Q-switched Nd:YAG laser (1064 nm, 10 ns, 5 Hz) to remove tattoos. Twenty-five patients with 39 blue-black or multicolored tattoos (14 previously untreated, 25 Q-switched ruby laser-resistant) were exposed in randomly derived quadrants with 6, 8, 10, or 12 J/cm2 at 3 to 4 week intervals for a total of four treatment sessions. RESULTS: An excellent response (> 75% ink removal) was seen in 77% of the black tattoos and more than 95% of the black ink cleared in 11 (28%) of 39 tattoos at 10 to 12 J/cm2 after four treatment sessions. Colored inks were not as effectively removed. Response was related to fluence with greatest improvement noted in the quadrants treated with 10 and 12 J/cm2. No significant side effects, including pigmentary changes or scarring, were noted. Histopathologic examination demonstrated persistence of tattoo ink in clinically clear areas and confirmed the absence of fibrosis and granulomatous changes. CONCLUSION: The Q-switched Nd:YAG laser (1064 nm) effectively treats black tattoos with an excellent cosmetic outcome. Bright colors were minimally responsive to treatment. Higher doses were more effective and equally well tolerated.

Adult↗
PubMed1985

Comparative hematological data from animals implanted with a total artificial heart containing different valves.

A review of animals receiving a TAH with 4 mechanical valves suggests that the least damage to the blood cell components is associated with the BS valve when compared with the MH valve at similar heart rates. Clinical anemia in varying stages was observed in most animals in this study. However, most calves compensated for the increased rate of hemolysis and none required blood transfusions. The BS valve would appear to combine minimal turbulence and mechanical crushing in a physiological setting.

Animals↗