Method for Assessing Fractional Laser Thermal Damage

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Method for Assessing Fractional Laser Thermal Damage

PostPosted by DCNGA » Fri Aug 20, 2010 8:55 pm

http://www.ncbi.nlm.nih.gov/pubmed/19050518

Abstract
BACKGROUND: Fractional photothermolysis is extremely popular in skin rejuvenation and remodeling procedures. However, the extent of thermal cellular injury beyond the borders of the coagulated microcolumns produced with fractional phototherapy is undefined.

METHODS: Six abdominoplasty patients were pretreated with the Lux1540 Fractional Erbium device (Palomar, Inc., Burlington, Mass.) at various clinical laser settings. After tissue excision, the panni were immediately biopsied. Biopsy specimens were fixed in formalin, embedded in paraffin, sectioned, and evaluated with the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling (TUNEL) procedure for cellular necrosis/apoptosis. Tissue was sectioned horizontally and longitudinally to help define the depth and distribution of the microcolumns of injury in a three-dimensional plane.

RESULTS: The extent of cellular necrosis/apoptosis at variable depths within the epidermis and dermis was demonstrated successfully with the TUNEL technique. After the Lux1540 treatment, TUNEL-positive nuclei were identified in a vertically oriented fashion that extended from the epidermis into the papillary and reticular dermis, highlighting the areas of injury. The TUNEL-positive nuclei defined lesions that were approximately 175 to 225 microm in diameter and penetrated to variable depths (200 to 900 microm), depending on the fluence used for treatment (18 to 100 mJ).

CONCLUSIONS: TUNEL immunofluorescent labeling provided an accurate assessment of cellular damage within and surrounding the microthermal zones of coagulated collagen with respect to column depth and width. Because of its specificity, the TUNEL assay can be a useful adjunct to other histologic stains used to characterize cellular damage and matrix denaturation in skin treated with any fractional ablative or nonablative laser device.
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Re: Fractional Laser/Irreversible chromosomal Damage

PostPosted by WG1 » Fri Aug 20, 2010 9:48 pm

Okay. They mean specific cells. Chromosomal damage in specific cells. those Cells die and voila, fat loss. Right?
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Re: Fractional Laser/Irreversible chromosomal Damage

PostPosted by DCNGA » Fri Aug 20, 2010 9:59 pm

Well, they mention cellular necrosis and apotosis which I think both mean death. It's confusing. We need a scientist to read this to interpret it for us.
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Re: Fractional Laser/Irreversible chromosomal Damage

PostPosted by DCNGA » Fri Aug 20, 2010 10:01 pm

This is the passage that perked up my ears:

However, the extent of thermal cellular injury beyond the borders of the coagulated microcolumns produced with fractional phototherapy is undefined.
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Re: Fractional Laser/Irreversible chromosomal Damage

PostPosted by WG1 » Fri Aug 20, 2010 10:11 pm

I wonder how hard it is to ask the authors direct questions.

I thought this is what was going on because of the lipidperioxidation study. I tried to get somebody to give me a TUNEL assay here. That's why, again, I think that the fat cells are so important. Like in my NOSE!! They replace the dead cells.
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Re: Fractional Laser/Irreversible chromosomal Damage

PostPosted by DCNGA » Mon Aug 23, 2010 10:20 pm

I contacted someone who had done 'tissue staining' as part of their lab work in a universtity. I asked her what this study meant. This is her response:

I read the paper. H&E and trichrome staining are standard methods for evaluating cell damage. I've done a lot of tissue processing, cutting, and staining for my university job using these staining methods--almost every pathologist expects at least H&E (hematoxylin and eosin). It's pink/orange to blue purple, imparting different colors on different cell types and aspects of the cells.

http://en.wikipedia.org/wiki/H%26E_stain

Trichrome is used when details are needed regarding connective tissue. It adds a third color, usually another blue or a green.

you can see some trichromes here:

http://131.229.114.77/microscopy/course ... ogy03.html

But this paper shows that a new method called TUNEL provides more detail to the extent and borders of tissue damage than typical staining procedures do as it stains areas with DNA nicks a bright fluorescent green. You would not see those nicks with H&E or trichrome.

The authors say it's necessary to do this to get a better grip on tissue damage. Although there have been papers on H&E and trichrome of fraxel-ed tissues, they are ambiguous and there isn't enough evidence to say that Fraxel is providing a true histological benefit. They also say it's necessary to get a better grip on what is tolerated (how many passes, strength of the beam, etc.).

In this paper they tested abdominal tissue with only 1-3 passes. They emphasize that facial fraxels might be completely different and more damage could take place.
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Re: Fractional Laser/Irreversible chromosomal Damage

PostPosted by Hummbird123 » Tue Aug 24, 2010 12:06 pm

"there isn't enough evidence to say that Fraxel is providing a true histological benefit." Then why are they in use!!!!! Once again, thank you FDA.
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