Effect of equal daily doses achieved by different power densities of low-level laser therapy at 635 nm on open skin wound healing in normal and corticosteroid-treated rats.

Optimal parameters of low-level laser therapy (LLLT) for wound healing are still discussed. Hence, our study was aimed to compare effects of different power densities of LLLT at 635 nm in rats. Four, round, full-thickness, skin wounds were made on the backs of 48 rats that were divided into two groups (non-steroid laser-treated and steroid laser-treated). Three wounds were stimulated daily with a diode laser (daily dose 5 J/cm(2)) each with different power density (1 mW/cm(2), 5 mW/cm(2), and 15 mW/cm(2)), whereas the fourth wound served as a control. Two days, 6 days, and 14 days after surgery, eight animals from each group were killed and samples were removed for histological evaluation. In the non-steroid laser-treated rats, significant acceleration of epithelization and collagen synthesis 2 days and 6 days after surgery was observed in stimulated wounds. In steroid laser-treated rats, 2 days and 14 days after surgery, a decreased leucocyte/macrophage ratio and a reduction in the area of granulation tissue were recorded, respectively. In conclusion, LLLT, by the method we used, improved wound healing in the non-steroid laser-treated rats, but it was useless after corticosteroid treatment.

Postsurgical administration of estradiol benzoate decreases tensile strength of healing skin wounds in ovariectomized rats.

BACKGROUND: The most effective method of increasing the level of estrogen in the wounds of post-menopausal women undergoing routine surgical procedures is by long-term preoperative administration. However, in the case of acute surgery or trauma, the most effective method of increasing the level of estrogen is administration immediately pre- or postsurgery. This study, therefore, was aimed at assessing the effect of postsurgical administration of estradiol benzoate on wound healing in ovariectomized (OVX) Sprague Dawley rats. MATERIALS AND METHODS: Three months prior to the wound healing experiment, 16 rats were anesthetized and underwent ovariectomy, while the other eight rats were sham operated. Two parallel full thickness skin incisions and two round full thickness skin excisions were performed on the dorsum of each rat. Dose of 10 microg/d of estradiol benzoate was administered to eight OVX rats for 6 d postoperatively, whereas the other animals received a placebo. After 6 d, all animals were sacrificed and samples removed for biomechanical and histological evaluation. RESULTS: The mean wound tensile strength of OVX estrogen treated rats (9.54 +/- 3.24 g/mm(2)) was significantly lower compared with vehicle-treated OVX animals (14.57 +/- 4.12 g/mm(2)) as well as with control rats subjected to sham-OVX surgery (11.71 +/- 3.33 g/mm(2)). Nevertheless, the histological evaluation in OVX estrogen treated rats showed a significantly increased process of neo-angiogenesis associated with slightly decreased collagen deposition. CONCLUSION: Our results indicate that the question of the clinical significance of this type of hormone replacement therapy remains open and requires further research.

Histological assessment of the effect of laser irradiation on skin wound healing in rats.

OBJECTIVE: The purpose of this study was to evaluate, from the histological point of view, the effect of diode laser irradiation on skin wound healing in Sprague-Dawley rats. BACKGROUND DATA: Various biological effects have been described in different studies after low-level laser therapy (LLLT). METHODS: Two parallel full-thickness skin incisions were performed on the back of each rat (n = 49) and immediately sutured. After surgery, one wound of each rat was exposed to laser irradiation (continuous mode, 670 nm, daily dose 30 J/cm2), whereas the parallel wound was not irradiated and served as control. Both wounds were removed 24, 48, 72, 96, 120, 144, and 168 h after surgery and routinely fixed and embedded in paraffin sections, stained with hematoxylin and eosin, van Gieson, periodic acid Schiff + periodic acid Schiff diastase, Mallory's phosphotungstic hematoxylin, and azur and eosin, and histopathologically evaluated. RESULTS: As compared to nonirradiated control wounds, laser stimulation shortened the inflammatory phase as well as accelerated the proliferative and maturation phase, and positively stimulated the regeneration of injured epidermis and the reparation of injured striated muscle. CONCLUSION: LLLT at 670 nm positively influences all phases of rat skin wound healing.

In vivo monitoring the changes of interstitial pH and FAD/NADH ratio by fluorescence spectroscopy in healing skin wounds.

The aim of our study was to evaluate the changes of interstitial pH and flavin adenine dinucleotide (FAD)/reduced nicotinamide adenine dinucleotide (NADH) ratio in healing skin wounds using fluorescence spectroscopy in Sprague Dawley rats. In the experiment, excisional and incisional models of wound healing were used. The florescein as the pH-sensitive probe using excitation spectra (lambda(Em) = 535 nm) was used for the measurement of pH changes, and synchronous fluorescence spectra (Deltalambda = 60 nm) for the monitoring of FAD/NADH ratio changes were measured from the surfaces of healing wounds. Increase of interstitial pH and FAD/NADH ratio was recorded during the time interval from the 15th to the 65th minute after surgery. The decrease of pH between the 48th and the 72nd hour after surgery as well as the increase of FAD/NADH ratio between the 72nd and the 96th hour of wound healing were recorded. The results indicate that the use of fluorescence spectroscopy may be considered as a valuable tool for noninvasive in vivo monitoring of selected redox parameters in the early phases of wound healing.