Effects of Epidermal Growth Factor on Lipid Peroxidation and Nitric Oxide Levels in Oral Mucosal Ulcer Healing: A Time-Course Study

Purpose Epidermal growth factor (EGF) has been used as a vulnerary agent. Epidermal growth factor accelerates wound healing. Nitric oxide (NO) is considered to be an important factor which is involved in wound healing. The objective of this study was to examine the effects of interactions between exogenous EGF and NOx which may have either similar or quite opposed properties in the process of oral wound repair on different days. In addition, lipid peroxidation was found to be an indicator of free radical damage. Methods Five-month-old New Zealand albino male rabbits were used for this study. A surgical incision was made in the right mandibula diestema region of the rabbits, which were then divided into controls and EGF implanted groups. All parameters were analyzed by spectrophotometry. Results In the EGF-implanted groups, both the NOx and lipid peroxidation indicator levels significantly decreased in comparison to those of the control groups on the first day after wounding. However, on the 3rd and 5th days after wounding, the NOx levels of the tissue strips also decreased in both modalities, but there was no significant alteration between the 3rd and 5th day after wounding. Conclusion It was concluded that EGF affects oral wound healing by downregulating both the lipid peroxidation and NOx levels, and it may thus be considered to be an oxygen radical scavenger.     

The healing-promoting effect of saliva on skin burn is mediated by epidermal growth factor (EGF): role of the neutrophils

Local skin trauma induces inflammatory responses resulting in local tissue and distant organ injury. EGF, a polypeptide hormone, mainly produced in saliva, is one of the major accelerators in wound healing. Wistar albino rats of both sexes received either bovine serum albumin or EGF (10 microg/kg) subcutaneously before a circular (18 mm diameter) partial thickness burn was induced. Afterwards, some rats were placed in separate cages to prevent licking, while the others were caged together to allow wound-licking. Treatments were continued for 5 more days and on the 5th day animals were decapitated. Histopathological analysis of skin damage and dermal myeloperoxidase (MPO) activity, as an index for neutrophil activity, were evaluated. Oxidant injury to the liver and intestines was determined by measuring glutathione (GSH) and malondialdehyde (MDA) levels, as well as MPO activity. The results demonstrate that healing of the burn wound on the skin is accelerated by both wound-licking and EGF administration, which also attenuated tissue neutrophil accumulation, suggesting the role of neutrophils as the source of mediators involved in delayed epithelial regeneration. Moreover, local dermal burn results in oxidant injury to the liver, concomitant with significant elevations in hepatic and intestinal GSH levels. Exogenous administration of EGF at physiological doses had no effect on inflammatory responses of the distant organs, while allowing the rats to lick the wound reduced the oxidant injury to the liver. Since saliva or EGF enhances skin wound healing, topical use of EGF-rich artificial saliva merits consideration for its use in burn patients.     

外用中药对兔创面表皮细胞生长因子的影响

目的 :探讨外用中药对白兔创面愈合不同时期肉芽组织中表皮细胞生长因子 (EGF)的影响与创面愈合之间的关系。方法 :采用手术方法造成背部的深创面白兔 85只。随机分成愈创膜组、生肌愈皮膏组和凡士林组。 3组创面分别应用相应药物治疗。分别于术后第 3、5、7、11、15天 ,以放射免疫法测定创面肉芽组织EGF含量。结果 :术后第 3、5、7天 ,2个中药组创面肉芽组织中EGF含量均高于凡士林组 (P <0 .0 1)。且 2个中药组第 5天时EGF含量均达到整个愈合过程中的峰值 ,在第 7天时仍保持高浓度。而凡士林组第 7天时才达到高峰。第 11、15天时 3组EGF含量逐渐减少 ,各时间点 2个中药组间比较差异无显著性意义 (P >0 .0 5 )。结论 :愈创膜及生肌愈皮膏均能增加早、中期白兔创面肉芽组织的EGF含量 ,从而加快创面的愈合。     

Local arginine supplementation results in sustained wound nitric oxide production and reductions in vascular endothelial growth factor expression and granulation tissue formation

OBJECTIVE: The goal of this work was to test the functional role of L-arginine in promotion of nitric oxide (NO) production and the vigorous granulation tissue formation characteristic of this wound model. BACKGROUND: Therapeutic use of supplemental arginine has been proposed as a safe and efficacious method to produce NO from nitric oxide synthase (NOS) and to produce proline and polyamines from arginase to improve wound healing. Although NO appears to be necessary to promote wound healing, the preferential metabolism of arginine to NO via NOS 2 may be detrimental if maintained beyond the initial days of healing. METHODS: A ventral hernia, surgically created in the abdominal wall of 12 swine, was repaired with silicone sheeting and skin closure. Osmotic infusion pumps, inserted in remote subcutaneous pockets, continuously delivered saline (n = 6) or L-arginine (n = 6) into the wound environment. Granulation tissue thickness was determined by ultrasonography. Fluid was aspirated serially from the wound compartment for measurements of nitrite/nitrate (NOx), vascular endothelial growth factor (VEGF), transforming growth factor-beta1 (TGF-beta1), and amino acid concentrations. On day 14, the animals were sacrificed and the abdominal wall was harvested for immunohistochemical and molecular analysis. RESULTS: In animals receiving saline, a nearly linear four-fold increase in granulation tissue thickness was measured during the 14-day interval. In contrast, quantitative ultrasound analysis detected significant reductions in L-arginine infused granulation tissue thickness compared with controls between days 4 and 14 (P < 0.05). Wound vessel count and luminal vascular surface area estimates derived from image analysis of histological sections were two- to three-fold lower in the L-arginine animals compared with controls (P < 0.05). Significant and sustained increases in wound fluid NOx levels were noted in L-arginine animals compared to saline controls (230 microM versus 75 microM at day 14, P < 0.05). Conversely, late VEGF levels (days 11 to 14) were reduced in the L-arginine animals compared to controls (7500 pg/ml versus 10,000 pg/ml at day 11, P < 0.05; 7250 pg/ml versus 11,101 pg/ml at day 14, P < 0.05). Arginine concentrations remained two- to four-fold greater in L-arginine treated animals compared with controls over the entire time course (P < 0.05). There were no significant differences in concentrations of ornithine, citrulline, or proline noted between groups over the 14-day period. Finally, TGF-beta1 levels were unaffected by L-arginine treatment. CONCLUSION: Although NO appears to be necessary for granulation tissue formation, early supplemental arginine may disturb the reciprocal regulation of NOS 2 and arginase, leading to the preferential metabolism of arginine to excess NO rather than ornithine, with consequent reductions in angiogenesis and granulation tissue formation.     

An investigation on burn wound healing in rats with chitosan gel formulation containing epidermal growth factor

Various studies have shown that chitosan is effective in promoting wound healing. In this study, we aimed to develop an effective chitosan gel formulation containing epidermal growth factor (EGF), and to determine the effect on healing of second-degree burn wounds in rats. Ten micrograms per millilitre EGF in 2% chitosan gel was prepared. In an in vitro study to investigate release of EGF from the formulations, the release rate was 97.3% after 24 h. In in vivo studies, animals were divided into six groups as follows: silver sulfadiazine [Silverdin cream (SIL)], chitosan gel with and without EGF (EJ, J), EGF solution (ES) and untreated control groups [unburned (S) and untreated (Y) rats] applied groups, respectively. A uniform deep second-degree burn of the backskin was performed with water heated to 94+/-1 degrees C during a 15-s exposure. The EGF formulations were repeatedly applied on the burned areas with a dose of 0.160 microg/cm2 for 14 days (one application per day). Healing of the wounds was evaluated immunohistochemically, histochemically and histologically on the tissue samples. When the results were evaluated immunohistochemically, there were significant increases in cell proliferation observed in the EGF containing gel applied group (p<0.001). The histochemical results showed that the epithelization rate in the EJ group was the highest compared to the ES group results (p<0.001). The histological results indicated and supported these findings. It can be concluded that a better and faster epithelization was observed in the EJ group compared to the other groups.     

EGF increases short-term type I collagen accumulation during wound healing in diabetic rats

Continuous topical application of epidermal growth factor (EGF) to granulation tissue increases the rate of collagen accumulation. It is believed that the clinical use of growth factors, such as EGF, may become common in the treatment of impaired wound healing in the near future. Impairments in the production and degradation of wound collagens have been demonstrated in diabetes mellitus. We studied the effects of a single, local application of EGF on collagen content, collagenase activity, and the ratio of type III and type I collagens within granulation tissue using polytetrafluoroethylene (PTFE) wound cylinders in 48 streptozotocin-induced diabetic rats in order to determine potential benefits of EGF to wound healing in diabetics. Wound collagen content in EGF-treated diabetic animals was significantly higher than in diabetic controls during the first 10 days of wound healing (236% on day 5, P less than .001; 140% on day 10, P less than .01), but decreased to significantly lower levels by day 15 of healing (71% of diabetic controls, P less than .01; 47% of nondiabetic controls, P less than .01). An 18% increase in diabetic wound protease activity was observed following application of EGF (P less than .001). The ratio of type III collagen to total wound collagen within the granulation tissue was significantly reduced (P less than .001) following EGF application. We demonstrate that a single, topical application of EGF promotes early synthesis of type I collagen, thereby deranging the usual type III/total collagen ratio, and is associated with increased wound protease activity.     

Beneficial effects of chrysin on the reproductive system of adult male rats

In this study, the beneficial effect of chrysin, a natural flavonoid currently under investigation due to its important biological activities, on reproductive system of rats was investigated. Rats (n = 16) were divided randomly into two equal groups. Rats in control group were given corn oil as carrier. Chrysin was orally administered at the dose of 50 mg kg(-1) per day by gavages, and it was dissolved in corn oil for 60 days. Tissue thiobarbituric acid reactive substances (TBARS) and glutathione (GSH) levels, antioxidant enzyme activity (CAT, SOD and GSH-Px), sperm parameters (motility, concentration and abnormal sperm rate), reproductive organ weight (testes, epididymis, vesicula seminalis, prostate) and serum testosterone levels were determined in the rats. Our results indicated that chrysin significantly increased GSH, CAT, GSH-Px and CuZn-SOD levels, but did not change the formation of TBARS significantly. In addition, sperm motility, sperm concentration and serum testosterone levels significantly increased, whereas abnormal sperm rate significantly decreased with chrysin treatment. In conclusion, it is suggested that treatment with chrysin can positively affect the reproductive system in rats, and it can be used for the treatment of male infertility.     

Topical embryonic stem cells enhance wound healing in diabetic rats

The effects of embryonic stem cells (ESCs) on diabetic wound healing were investigated using an excisional skin wound model in 110 diabetes‐induced rats. We transplanted a clonal population of ESCs (5 × 10⁶) by topical injection into full thickness skin wounds. Four study groups were used; nondiabetic rats as a control, non‐insulin controlled diabetic rats not treated with ESCs, insulin controlled diabetic rats not treated with ESCs, and insulin controlled diabetic rats treated with ESCs. Five rats in each experimental group were sacrificed on days 1, 5, 10, 15, and 20 after wounding. Wounds images were acquired daily and wound sizes were calculated. We measured the mRNA levels of epidermal growth factor (EGF) and vascular endothelial growth factor (VEGF), and fibronectin levels in extracellular matrix, and assessed wound healing by assessing histological parameters of epidermal regeneration, granulation tissue thickness, and angiogenesis. In the ESC‐treated group, wound sizes were significantly smaller than in the insulin controlled diabetic group not treated with ESCs on days 5 and 10 (p < 0.05), and EGF and VEGF levels were markedly higher on days 5 and 10, fibronectin levels on day 5 after injection. All histological scores in the ESC‐treated group were significantly higher than those of the insulin controlled diabetic group on day 5 (p < 0.05). Our results shows that topical ESCs enhance diabetic wound healing during the early stage, and suggest that ESCs transplantation offers a novel therapeutic modality for the treatment of diabetic wounds. © 2011 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29: 1554–1562, 2011     

Quercetin prevents 2,3,7,8-tetrachlorodibenzo-p-dioxin-induced testicular damage in rats

The protective effect of quercetin on 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced testicular damage in rats was investigated. Twenty-two rats were equally divided into four groups; first group was kept as control and given corn oil as carrier. In second group, TCDD was orally administered at the dose of 2 μ (kg week)(-1) for 60 days. In third group, quercetin was orally administered at the dose of 20 mg (kg day)(-1) by gavages, and in fourth group TCDD and quercetin were given together at the same doses. Although TCDD increased the formation of thiobarbituric acid reactive substances (TBARS) significantly, it caused a significant decline in the levels of glutathione (GSH), catalase (CAT), GSH-Px and CuZn-Superoxide Dismutase (CuZn-SOD) in rats. In contrast, quercetin significantly increased the GSH, CAT, GSH-Px and CuZn-SOD levels but decreased the formation of TBARS. In addition, sperm motility, sperm concentration and serum testosterone levels were significantly decreased but abnormal sperm rate and testicular damage were increased with TCDD treatment. However, these effects of TCDD on sperm parameters, histological changes and hormone levels were eliminated by quercetin treatment. Our results show that administration of TCDD induces testicular damage (oxidative stress, testes tissue damage, serum hormone level and sperm parameters), and quercetin prevents TCDD-induced testicular damage in rats. Thus, quercetin may be useful for the prevention and treatment of TCDD-induced testicular damage.     

The effect of partial unilateral ureteral obstruction release and allopurinol on the renal malondialdehyde and glutathione levels

PURPOSE: The aim of the present study was to evaluate whether relief of partial unilateral ureteral obstruction (PUUO) with or without antioxidant drug affect renal tissue malonedialdehyde (MDA) and glutathion (GSH) levels. MATERIALS AND METHODS: A total of 25 rats were used in this PUUO study. Partial unilateral ureteral obstruction was created by the burial of the upper one-third of the left ureter in the psoas muscle. The rats were sacrificed on 28th day following PUUO. Relief of the obstruction was performed twenty minutes before sacrifice by cutting the proximal ureter in reperfusion group. 50 mg/kg intraperitoneal allopurinol was administered 20 minutes before relief of obstruction in the antioxidant group. Renal tissue MDA and GSH levels were measured in both kidneys. RESULTS: At the end of the study 5, 7 and 7 rats could only be interpreted in sham, reperfusion and antioxidant groups, respectively. While the mean left and right renal MDA and GSH levels were statistically different from each other in reperfusion group (P < 0.001), there were no significant differences in the sham (P > 0.05) and antioxidant (P > 0.05) group. Both the mean sham group left and right renal tissue MDA or GSH levels were significantly different from reperfusion group, but only the mean sham group left renal tissue MDA and right renal tissue GSH levels were not statistically different from antioxidant group (P < 0.05). The mean left or right renal MDA and GSH tissue levels of the antioxidant group were statistically different from reperfusion group (P < 0.05) except for the right renal tissue GSH level (P > 0.05). CONCLUSION: Partial unilateral ureteral obstruction leads to oxidative injury by relief of obstruction in both kidneys. The antioxidant allopurinol has a beneficial effect on renal MDA and GSH levels in both kidneys.     

神经生长因子调控烧伤创面的实验研究

目的 研究神经生长因子（ＮＧＦ）在烧伤创面愈合的作用,探索烧伤创面愈合机制。方法２０ｋｇ小白家猪６只为实验对象。用控温控压电烫仪在每只猪背部制成２４个直径为２．５ｃｍ的圆形深Ⅱ度烧伤创面。分为四组,分别为创面局部应用１、２．５和５μｇ／ｍｌ的ＮＧＦ实验组和不含ＮＧＦ的生理盐水对照组。在用药后３、５和９天分别取创面组织进行表皮生长因子（ＥＧＦ）受体,ＥＧＦ,ＮＧＦ受体,ＮＧＦ,ＣＤ６８,ＣＤ３免疫组     

Continuous EGF application impairs long-term collagen accumulation during wound healing in rats.

Continuous topical application of epidermal growth factor (EGF) to granulation tissue has been demonstrated to increase the rate of collagen accumulation in wounds. Studies from this laboratory have indicated that a single topical application of EGF leads to a short period of elevated wound collagen content, followed by a rapid breakdown of this newly acquired collagen. In light of recent clinical trials of EGF as an aid to wound healing, we studied the long-term effects of continuous EGF injection. Standard polytetrafluoroethylene (PTFE) wound cylinders were surgically placed in the dorsal midline of 40 male Sprague-Dawley rats. Rats received EGF daily for 14 days, at which time all injections ceased. Wound cylinders were removed for analysis from five test animals and five controls on study days 14, 21, 28, and 35. Wound collagen content in EGF-treated animals was significantly higher than in controls on the 14th day of the study (330% higher, P less than .002), but dropped to lower levels on each succeeding day (day 21: 97% of control, NS; day 28: 63% of control, NS; day 35: 72% of control, P less than .03). There was a significant increase in wound collagenase activity only on days 14 and 21, but not on days 28 and 35. We demonstrated that continuous application of EGF may artificially elevate wound collagen content, thereby leading to increased wound catabolism on cessation of treatment.     

Dual effects of atmospheric pressure plasma jet on skin wound healing of mice

Cold plasma has become an attractive tool for promoting wound healing and treating skin diseases. This article presents an atmospheric pressure plasma jet (APPJ) generated in argon gas through dielectric barrier discharge, which was applied to superficial skin wounds in BALB/c mice. The mice (n = 50) were assigned randomly into five groups (named A, B, C, D, E) with 10 animals in each group. Natural wound healing was compared with stimulated wound healing treated daily with APPJ for different time spans (10, 20, 30, 40, and 50 seconds) on 14 consecutive days. APPJ emission spectra, morphological changes in animal wounds, and tissue histological parameters were analyzed. Statistical results revealed that wound size changed over the duration of the experimental period and there was a significant interaction between experimental day and group. Differences between group C and other groups at day 7 were statistically significant (p < 0.05). All groups had nearly achieved closure of the untreated control wounds at day 14. The wounds treated with APPJ for 10, 20, 30, and 40 seconds showed significantly enhanced daily improvement compared with the control and almost complete closure at day 12, 10, 7, and 13, respectively. The optimal results of epidermal cell regeneration, granulation tissue hyperplasia, and collagen deposition in histological aspect were observed at day 7. However, the wounds treated for 50 seconds were less well healed at day 14 than those of the control. It was concluded that appropriate doses of cold plasma could inactivate bacteria around the wound, activate fibroblast proliferation in wound tissue, and eventually promote wound healing. Whereas, over doses of plasma suppressed wound healing due to causing cell death by apoptosis or necrosis. Both positive and negative effects may be related to the existence of reactive oxygen and nitrogen species (ROS and RNS) in APPJ.     

Effects of topical glutathione treatment in rat ischemic wound model

Oxidative stress secondary to ischemia can cause physiopathologic changes that adversely affect wound healing. In this experimental study, we hypothesized that the topical use of esterified glutathione, a well-known antioxidant, can minimize the effects of oxidative stress by an increase in intracellular glutathione and accelerate wound healing by increasing the contraction capacity of fibroblasts and preventing keratinocytes from apoptosis in a rat ischemic wound model.Experimental models were divided into 3 groups as treatment, control, and healthy. Bipedicled flaps were elevated from the dorsum of the rats, and 6-mm punch wounds were created at the end of the first day when the ischemia is most apparent. Wounds were followed histopathologically and immunohistochemically, and matrix metalloproteinase (MMP)-1 and tissue inhibitors of metalloproteinase (TIMP-1) levels were measured by ELISA. Samples were collected at 0, 5, 8, 10, and 12 days.Histopathologic evaluation revealed significant extracellular matrix deposition and reepithelization every fifth day in treatment and healthy groups when compared with control group. Immunohistochemical evaluation revealed increased apoptosis in basal keratinocytes in the control group when compared with the other groups. The evaluation of the samples collected at 5 and 8 days revealed increased MMP-1 levels in treatment and control groups, but the increase in TIMP-1 levels was more significant than MMP-1 levels in treatment group. MMP-1/TIMP-1 ratio was significantly low in the treatment group.Our results showed that topical GSH treatment can reduce oxidative stress, and the reestablishment of the MMP-1/TIMP-1 ratio gives way to adequate and regular extracellular matrix production and reepithelization. It is concluded that esterified GSH, which is experimentally shown to be effective in ischemic wound healing, can be used clinically in ischemic wounds.     

Nitric oxide synthase isoform expression in a porcine model of granulation tissue formation

BACKGROUND: This study was designed to determine whether the nitric oxide (NO) pathway is involved in wound granulation tissue formation. METHODS: A section of the pig abdominal wall (excluding the skin) was excised, creating an incisional hernia. The resulting defect was repaired with silicone sheeting in a manner that mimics a temporary abdominal wall closure. During the 14-day experimental period, porcine omentum adhered to the peritoneal edges of the defect and a highly vascularized granulation tissue formed on both sides of the sheeting. Granulation tissue thickness and wound fluid volume were monitored by ultrasonography and epigastric artery flow velocity was monitored by color Doppler flow analysis at days 2, 4, 7, 9, 11, and 14. Fluid was serially harvested from the wound compartment at days 2, 4, 7, 9, 11, and 14 for nitrite/ nitrate (NOx) analysis. Finally, granulation tissue was harvested at day 14 for immunohistochemical and molecular analyses. RESULTS: There was a significant increase in granulation tissue thickness and wound fluid volume during the 14-day study period. Blood flow to the wound increased significantly by day 4 and returned toward baseline by day 14. Wound fluid NOx levels significantly increased from days 7 to 11 and then decreased to near baseline values by day 14. Wound fluid arginine levels significantly decreased when compared with peritoneal fluid and plasma levels at day 14, while wound fluid ornithine levels significantly increased. Immunohistochemical analysis of granulation tissue at day 14 revealed nitric oxide synthase (NOS) 2 was present in the majority of the cells in the granulation tissue. NOS 3 was expressed in endothelial cells only, and NOS 1 expression was not observed in the granulation tissue. CONCLUSIONS: This study suggests that NO, NOS 2, and arginine may play critical roles in granulation tissue formation and wound healing. Arginase and NOS 2 may compete for available arginine as a substrate, thereby limiting later NO production in favor of sustained ornithine synthesis.     

Influence of Hydroxyethyl Starch on Healing of Colonic Anastomosis in a Rat Model of Peritonitis

Background: This study was designed to evaluate the role of different intravascular volume replacement regimens of HES 130/0.4 on wound healing process in left colonic anastomoses in the presence of intra-abdominal sepsis induced by murine model of cecal ligation and puncture (CLP). Methods: The left colonic anastomosis was performed in 40 rats that were divided into five groups (n = 8/group): saline controls (30 ml/kg); CLP plus saline (30 ml/kg); CLP plus HES (7.5, 15, or 30 ml/kg, respectively). Saline or HES was treated before the construction of left colonic anastomosis and on a regular daily basis. Anastomotic bursting pressures were measured in vivo on day 5. Tissue samples were obtained for analyses of hydroxyproline (HP) contents, myeloperoxidase (MPO) acivity, malondialdehyde (MDA), reduced glutathione (GSH) levels, and nuclear factor-κ B (NF-κ B) activation. The plasma levels of tumor necrosis factor (TNF)-α and interleukin (IL)-6 were also measured. Results: Intra-abdominal sepsis led to significant decreases in colonic anastomotic bursting pressures, and perianastomotic tissue HP contents and GSH levels, along with increases in perianastomotic tissue MPO activity, MDA levels and NF-κ B activation and plasma levels of TNF-α and IL-6. After treated with HES, these provoked perianastomotic tissue MPO activity, MDA levels, NF-κ B activation, and plasma levels of TNF-α and IL-6 were suppressed and GSH levels were restored, especially in 15 ml/kg HES group. Without obvious influence on systemic nutritional condition, HES 15 ml/kg but not HES 7.5 ml/kg significantly increased anastomotic bursting pressures, and perianastomotic tissue HP contents. However, HES 30 ml/kg even led to adverse effects on anastomotic bursting pressures. Conclusions: This study showed that moderate doses (15 ml/kg) of HES 130/0.4 administration significantly prevented this intraperitoneal sepsis-induced impaired anastomotic healing of the left colon. It also suggested the possibility of poorer anastomotic healing receiving HES at higher doses (30 ml/kg). Clearly, HES 130/0.4 now should not be recommended to use at a high doses postoperatively in sepsis.     

Epidermal growth factor‐containing wound closure enhances wound healing in non‐diabetic and diabetic rats

Background: This study was designed to elucidate the in vivo efficacy of epidermal growth factor (EGF) on wound healing in non diabetic and diabetic rats. Methods: Ninety‐six male Wistar‐Albino rats were randomly divided into six groups. Saline‐moistened gauze, pure gelatin or EGF in gelatin‐microsphere dressings were used in a dermal excision model in both normal and streptomycin‐induced diabetic rats. Wound healing was evaluated on day 7 and 14. Reduction in wound area, hydroxypyroline content and tensile strength of the wound were evaluated in each rat. Tissue samples taken from the wounds were examined histopathologically for reepithelialisation, cellular infiltration, number of fibroblasts, granulation and neovascularisation. Results: On day 7, the use of EGF‐containing dressing was observed to reduce the wound area better when compared with the other dressings tested. This effect was significant in normal rats rather than diabetic rats. The difference in reduction of wound area did not persist on day 14. No significant effect on hydroxyproline content of the wound was found with EGF‐containing dressing in either normal or diabetic rats. There was a statistically significant increase in tensile strength values of EGF‐applied non diabetic rats over the 14 day period. An increase in tensile strength was prominent in also EGF‐applied diabetic rats on day 14. Histological examination revealed higher histopathologic scores in EGF‐applied diabetic and non diabetic rats. Conclusion: These findings implicate that use of EGF in gelatin‐microsphere dressings improves wound healing both in normal and diabetic rats.     

Time-dependent effects of low-level laser therapy on the morphology and oxidative response in the skin wound healing in rats

This study aims to investigate the effect of different energy densities provided by low-level laser therapy (LLLT) on the morphology of scar tissue and the oxidative response in the healing of secondary intention skin wounds in rats. Twenty-four male adult Wistar rats were used. Skin wounds were made on the backs of the animals, which were randomized into three groups of eight animals each as follows, 0.9% saline (control); laser GaAsAl 30 J/cm² (L30); laser GaAsAl 90 J/cm² (L90). The experiment lasted 21 days. Every 7 days, the wound contraction index (WCI) was calculated and tissue from different wounds was removed to assess the proportion of cells and blood vessels, collagen maturation index (CMI), thiobarbituric acid reactive substance (TBARS) levels and catalase activity (CAT). On the 7th and 14th days, the WCI and the proportion of cells were significantly higher in groups L30 and L90 compared to the control (p?<?0.05). At all the time points analyzed, there was a greater proportion of blood vessels and a higher CMI in group L90 compared to the other groups (p?<?0.05). On the 7th and 14th days, lower TBARS levels and increased CAT activity were found in the L90 group compared to the control (p?<?0.05). On the 7th day, a moderately negative correlation was found between TBARS levels and WCI, CMI and CAT in all the groups. LLLT may modulate the oxidative status of wounded tissue, constituting a possible mechanism through which the LLLT exerts its effects in the initial phases of tissue repair.