الفهرس 
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Abstract
The present study aimed to differentiate between thermal cutaneous burn and other common cutaneous burns as: scald, thermal and electrical burn injuries on adult female albino rats by detecting the structural changes in skin and hair tissues using scanning-electron microscope, detecting the effects of burns on biochemical parameters in skin tissue, and gene expression of cutaneous aquaporin-3 gene using quantitative Real-Time PCR, as well as to emphasis their histopathological alterations in skin tissue of rat. Therefore, female albino rats (3-4 months old, weighing about 130-150 g) were used in this experiment. The animals were fed standard ration and with ad-libtum access to water. Rats were housed in metal box cages for one week prior to the experiment for acclimatization. After acclimatization period, rats were randomly divided into five groups, group one served as control without any cutaneous burn, group two subjected to direct contact thermal burn using a heated circular metal plate for 10 seconds, group three subjected to scalding by using boiled water for 8-10 seconds, group four subjected to chemical burn via concentrated acid (98% H₂SO₄)for 5 minutes and group five subjected to electrical burn using a double copper wire for 20 seconds. At the end of burns induction in each group, skin and hair tissue samples were collected from the site of the burn injury to detect the differences between each type of burns through scanning-electron microscopic analysis on skin and hair tissues, biochemical parameters in skin tissue homogenate, level of cutaneous aquaporin-3 gene mRNA gene expression and histopathological changes in skin tissue.
Our results revealed that:
Thermal, scald, chemical and electrical burn injuries showed a different morphological appearance among each type of skin burn. There were structural alterations in scanning-electron microscopic analysis of hair shaft and skin tissue among each group. There were a few numbers of affections including cracks and holes in the shaft of hair in scald and electrically burned animals, while more severe cracks and holes were found in hair shaft of chemically burned rats. These affections were observed also in hair shaft of thermally burned rats with singeing in hair.
There was a decrease in the cutaneous GST tissue activity in all groups, with the lowest levels appeared in chemically and electrically burned animals. While, there was an increment in cutaneous levels of LPO in all groups with the highest levels of LPO activity observed in chemically burned rats and the lowest levels showed in thermally burned rats. There was increasing in Il-6 levels in skin tissue of all groups. There was up regulation in cutaneous mRNA expression of AQP-3 gene in all groups.
Microscopic examination of skin tissue in rats exposed to different means of burn injuries showed Pathological lesions which contribute in differentiation among various types of cutaneous burn wounds.
Histological analysis to skin layers of rats subjected to direct thermal burn showed coagulation of the epidermal and dermal cells with degeneration of collagen fibers, as well asmultiple vesicles formation in the epidermal layer. Moreover, rats exposed to scald burn showed coagulation of the dermal cells with elongation of the epidermal cellular nuclei. While, microscopic examination of chemically and electrically burned rats’ skin tissues showed ballooning degeneration of the epidermal cell layer with vesicles formation in addition to coagulation of the dermal cell layer. However, in the chemical burn the vesicles formation were more prominent.
Therefore, from these results we can conclude that:
1. Scanning electron microscope can be used to monitor the structural alterations of the different types of skin burns.
2. Biochemical analysis of oxidative stress markers in skin tissues did not exhibit a significance in differentiation between different cutaneous burns.
3. Pro-inflammatory cytokine (Interleukin-6) can be used to differentiate among different cutaneous burns.
4. Molecular analysis of cutaneous AQP-3 gene expression can be used to differentiate among direct thermal, scald, chemical and electrical skin burns.
5. Histopathological examination can be used to differentiate among thermal, scald, chemical and electrical skin burns.