Random Pattern Skin Flaps In Rats Research Articles

The Promising Effect of Topiramate on Random-Pattern Skin Flap Survival in Rats.

Partial necrosis of skin flaps following plastic and reconstructive surgeries is one of the major problems in these medical interventions. This study was conducted to evaluate the beneficial effects of topiramate an anti-epileptic agent on ischemic random skin flaps. Twenty-four Wistar rats were provided and randomly divided into four experimental groups (control group and low-, intermediate- and high-dose treatment groups). A rat random-pattern skin flap model was performed in all groups, and animals in the low-, intermediate- and high-dose experimental groups were administered topiramate intraperitoneally at doses of 25, 50 and 100 mg/kg, respectively, 1 h before raising the flap and once daily for 7 consecutive days after the initial surgical procedure. Control rats received vehicle according to the same schedule. On postoperative day 7 the flap necrotic area was measured, and tissue samples were stained with hematoxylin and eosin for histological analysis. Furthermore, the oxidative stress in flap tissue was assessed by measuring the activity of superoxide dismutase (SOD), glutathione (GSH) level and the content of malondialdehyde (MDA). Treating animals with 50 and 100 mg/kg topiramate significantly decreased the necrotic flap areas as compared to the control group. Histological studies demonstrated that in intermediate and high dose topiramate groups the inflammatory cell numbers were attenuated and microvessel development were markedly increased. Furthermore, the MDA contents were significantly reduced and GSH levels were significantly increased in these groups as compared to the control group. However, the SOD activity was increased significantly only in high-dose group as compared to the control group. These findings indicated that topiramate in doses of 50 and 100 mg/kg increases random skin flap survival. This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Protective effects of icariin on dorsal random skin flap survival: An experimental study

This study was performed to examine the protective effects of icariin (ICA) on ischemic random skin flaps. A rat random-pattern skin flap model was established, and animals in the low-dose and high-dose experimental groups were administered ICA intraperitoneally at doses of 40 and 80 mg/kg, respectively, once daily for 7 days after the initial surgery. Control rats received vehicle according to the same schedule. Survival rates were observed and recorded using transparent graph paper, and flaps were obtained and stained with hematoxylin and eosin (H&E). The malondialdehyde (MDA) content and superoxide dismutase (SOD) activity in the flap tissue were assessed. The blood flow volume was determined by the laser Doppler method, and tissue expression levels of vascular endothelial growth factor (VEGF), interleukin-6 (IL-6), interleukin-1β, and phosphodiesterase 5 (PDE5) were scored immunohistochemically. The levels of proinflammatory cytokines, including tumor necrosis factor-α and IL-6, were determined by enzyme-linked immunosorbent assay. The main flap survival area was significantly larger in rats treated with ICA than in vehicle-treated controls. H&E staining showed an inhibitory effect of ICA on inflammation, especially at the high dose. In addition, ICA treatment was associated with decreases in the tissue MDA level, proinflammatory cytokine production, and the level of PDE5, but increases in SOD activity, blood flow volume, and the level of VEGF expression. The findings of the present study suggest that ICA is a potential therapeutic agent for random-pattern skin flap necrosis in the clinical setting.

Investigating the Effect of Korean Red Ginseng on the Viability of Random-Pattern Skin Flaps in Rats.

This experimental study investigated the efficacy of Korean Red Ginseng (KRG) extract in reducing the partial losses of random flaps. Forty Wistar Albino rats were randomly distributed into 4 groups as (A) control group, (B) stress group, (C) oral KRG group, and (D) intraperitoneal KRG group. The modified McFarlane flap of 9 × 3 cm with a caudal pedicle was harvested from the back of the rats in all the groups. Korean Red Ginseng was administered to groups C and D at standard doses for 10 days. After 10 days, the flaps were removed in all groups and were examined macroscopically, histopathologically, histochemically, and biochemically. The results were statistically analyzed and compared among the groups. The flap necrosis rates were significantly lower in groups C and D compared with groups A and B (P < 0.05). The vascular density, antioxidant activity, and hypoxia-inducible factor-1α levels were significantly higher in the groups C and D compared with the groups A and B (P < 0.05). Although vascular density, hypoxia-inducible factor-1α, and catalase levels were negatively correlated with the flap necrosis rates, there was a significantly positive correlation between malondialdehyde and necrosis rates. Korean Red Ginseng increases the viability of random pattern skin flaps, resulting in reduced rates of distal necrosis. Korean Red Ginseng has antioxidant activity and increases neovascularization.

Effectiveness of Bone Marrow Stromal Cell Sheets in Maintaining Random-Pattern Skin Flaps in an Experimental Animal Model

Bone marrow stromal cells can be applied therapeutically to enhance angiogenesis; however, the use of bone marrow stromal cell suspensions reduces efficiency because of low-level attachment. The authors hypothesized that bone marrow stromal cell sheets would facilitate cell fixation, thus enhancing angiogenesis. The authors investigated flap survival area and enhancement of angiogenic factors in a rat random-pattern skin flap model after application of bone marrow stromal cell sheets. Bone marrow stromal cell sheets (prepared from 7-week-old rat femurs) were cultured under four different hypoxic conditions. Sheets with the highest angiogenic potential, determined by an in vitro pilot study, were injected into subcutaneous layers of the rat dorsum (bone marrow stromal cell sheet group). A control group (phosphate-buffered saline only) was included. On day 2 after injection, caudally based random-pattern skin flaps (12 × 3 cm) were elevated. On day 7 after elevation, surviving skin flap areas were measured. Skin samples were harvested from each flap and gene expression levels of vascular endothelial growth factor and basic fibroblast growth factor were measured by quantitative real-time polymerase chain reaction. Skin flap survival area (71.6 ± 2.3 percent versus 51.5 ± 3.3 percent) and levels of vascular endothelial growth factor and basic fibroblast growth factor were significantly higher in the bone marrow stromal cell sheet group than in the control group (p < 0.05). Implantation of bone marrow stromal cell sheets increased the survival area of random-pattern skin flaps. Expression of angiogenic factors may have contributed to the increased flap survival.

Na+–H+ exchange inhibition attenuates ischemic injury in rat random pattern skin flap: The role of mitochondrial ATP-sensitive potassium channels

Necrosis of distal portion of skin flaps due to ischemia still remains a problem in plastic surgery. Following ischemia, a cascade of deleterious events including over-activity of Na+–H+ Exchanger (NHE) takes place. In present study we evaluated the effect of the potent NHE inhibitor, 5-(N-ethyl-N-isopropyl) amiloride (EIPA) on ischemic tissue injury in a skin flap model, and investigated the role of mitochondrial ATP-sensitive K+ channels (KATP) in this phenomenon. Seventy-eight rats were randomly divided into thirteen treatment groups (6 rats each). Four groups received different doses of EIPA in the flap. EIPA/GLY group received an effective dose of a KATP channel blocker, glibenclamide (GLY, 0.3mg/kg) intraperitoneally (i.p.) 30min before raising the flap, and a local effective dose of EIPA (0.1mM) immediately after raising the flap. EIPA/diazoxide group (EIPA/DIA) received a sub-effective dose of diazoxide (7.5mg/kg i.p.) 30min before raising the flap and a local sub-effective dose of EIPA (0.075mM). EIPA 0.1 and 0.2mM significantly increased flap survival area compared to control group (56.01±6.1%, P<0.001). The protective effect of EIPA (0.1mM) was abolished by administration of glibenclamide (0.3mg/kg i.p.). Co-administration of a sub-effective dose of EIPA (0.075mM), with a sub-effective dose of diazoxide (7.5mg/kg i.p.) significantly improved flap survival (P<0.05). We demonstrated that the NHE inhibitor, EIPA can increase random pattern skin flap survival. Administration of diazoxide potentiates this effect, while glibenclamide abolishes that, implicating that the protective effect of EIPA is mediated through mitochondrial-KATP channels.

Hypothyroidism improves random-pattern skin flap survival in rats

BackgroundThe protective effect of hypothyroidism against ischemic or toxic conditions has been shown in various tissues. We investigated the effect of propylthiouracil (PTU)/methimazole (MMI)-induced hypothyroidism and acute local effect of MMI on the outcome of lethal ischemia in random-pattern skin flaps. Materials and methodsDorsal flaps with caudal pedicles were elevated at midline and flap survival was measured at the seventh day after surgery. The first group, as control, received 1 mL of 0.9% saline solution in the flap before flap elevation. In groups 2 and 3, hypothyroidism was induced by administration of either PTU 0.05% or MMI 0.04% in drinking water. The next four groups received local injections of MMI (10, 20, 50, or 100 μg/flap) before flap elevation. Local PTU injection was ignored due to insolubility of the agent. ResultsHypothyroidism was induced in chronic PTU- and MMI-treated groups, and animals in these groups showed significant increase in their flap survival, compared to control euthyroid rats (79.47% ± 10.49% and 75.48% ± 12.93% versus 52.26% ± 5.75%, respectively, P < 0.01). Acute local treatment of skin flaps with MMI failed to significantly affect the flap survival. ConclusionThis study demonstrates for the first time that hypothyroidism improves survival of random-pattern skin flaps in rats.

Protective Effect of Pharmacologic Preconditioning with Pioglitazone on Random-Pattern Skin Flap in Rat is Mediated by Nitric Oxide System

Pioglitazone, a thiazolidinedione, is primarily used as an antidiabetic agent. In addition, recent reports have identified anti-ischemic and anti-inflammatory properties of pioglitazone through nitric oxide (NO) pathways. To determine the protective effects of pioglitazone on random-pattern skin flaps in a rat model. Forty-eight male Rats were randomly assigned to eight groups. Bipedicled dorsal skin flaps (2 × 8 cm) were elevated at the midline. In pharmacologic preconditioning groups, three different doses of pioglitazone (25, 40, 80, mg/kg; doses were selected according to our pilot study) gavaged 4 h before elevating flaps. Seven days after operation, the survival of skin flap was measured. For investigating the role of NO system, in other groups the nitric oxide synthase inhibitor N-nitro-L-arginine methyl ester hydrochloride (L-NAME, 10 mg/kg) was administered alone or with an effective dose of pioglitazone. Finally, in another group, subeffective dose of nitric oxide precursor L-arginine (100 mg/kg) was coadministered with subeffective pioglitazone. Significant increase in flap survival was seen with pioglitazone (40 mg/kg). This protective effect was abolished by systemic administration of L-NAME (10 mg/kg). Coadministration of subeffective doses of pioglitazone with subeffetcive L-arginine significantly improved flap survival. Pharmacologic preconditioning with pioglitazone improves survival of random-pattern skin flaps in rats through NO dependent mechanisms.

Mechanical Stimulation Improves Survival in Random-Pattern Skin Flaps in Rats

This was a study on the effects of 3-MHz ultrasound at 16- and 100-Hz pulse repetition frequencies on angiogenesis and viability of random-pattern skin flaps in rats. A cranially-based dorsal skin flap was raised in 60 EPM-Wistar rats, which were randomly divided into four groups: control, sham, 16-Hz and 100-Hz groups. The mean percentage of necrosis was as follows: control, 42% ± 13%; sham, 18% ± 13%; 16-Hz group, 13% ± 10%; and 100-Hz group, 15% ± 7%, with significant differences between the control and the other groups ( p < 0.001). The mean vascular density was as follows: control, 5% ± 2%; sham, 7% ± 2%; 16-Hz group, 21% ± 4%; and 100-Hz group, 24% ± 10%, with significant differences between control and ultrasound groups, and between the sham and ultrasound groups ( p < 0.001). Both ultrasound treatments (16- and 100-Hz PRFs) induced angiogenesis, and sham and ultrasound treatments improved viability of random-pattern skin flaps in rats. (E-mails: pascale.tacani@hotmail.com; sandra.dcir@epm.br)

Capsaicin on the viability of random-pattern skin flaps in rats

To evaluate the effects of capsaicin on the viability of ischemic random-pattern skin flaps in rats. Forty EPM1-Wistar rats were randomized into two groups of 20 animals each, the capsaicin group and the control group. A random-pattern skin flap measuring 10 x 4 cm was raised and a plastic barrier was placed between the flap and the donor site. After the surgical procedure, the control group was treated with an inert vehicle in the form of a cream applied uniformly to a rayon bandage which, in turn, was applied to the surface of the skin flap. The capsaicin group was treated in the same way, but in this case capsaicin was added to the cream. This procedure was repeated for two consecutive days. There was a significantly smaller amount of flap necrosis in the capsaicin group (35.07%) than in the control group (44.75%) (p=0.035). Topical administration of capsaicin improved the viability of ischemic random-pattern skin flaps in rats.

Improvement of the skin flap survival with the bone marrow‐derived mononuclear cells transplantation in a rat model

Partial necrosis of skin flaps remains a significant problem in plastic and reconstructive surgery. In this study we attempted to evaluate the effect of bone marrow-derived mononuclear cells (BM-MNCs) transplantation on improvement of skin flap survival in a rat random pattern skin flap model. Thirty Wistar rats were divided into three groups with each consisting of 10 rats. BM-MNCs and the adipose-derived stem cells (ADSCs) were transplanted into the subcutaneous tissue in the area where the flap would be dissected. The flaps were then raised two days after cells transplantation. The animals receiving the preoperative Dulbecco's Modified Eagle Medium (DMEM) treatment were used as the controls. On the 7th postoperative day, the survival areas of flaps were measured and tissues were collected for examinations. The results showed that the mean survival areas were 46.33 +/- 13.46% in the ADSCs group and 50.06 +/- 13.82% in the BM-MNCs group as the percentages of the total skin flaps, which were significantly higher than that in the control group (26.33 +/- 7.14%) (P < 0.05). Histological analysis showed increased neovascularization in the flap treated with BM-MNCs when compared with ADSCs transplantation. Survival BM-MNCs and ADSCs were detected in the flap tissues. Higher levels of the basic fibroblast growth factor (bFGF) and vascular endothelium growth factor (VEGF) were found in the BM-MNCs transplantation group (P < 0.05). The findings from this study demonstrated that preoperative treatment with BM-MNCs transplantation could promote neovascularization and improve flap survival. These effects of BM-MNCs on flap survival were comparable with ADSCs transplantation, but without necessity of in vitro cells expansion.

Effect of nicotine treatment and withdrawal on random-pattern skin flaps in rats

Background Tobacco use is associated with a high incidence of skin necrosis after surgery. The ideal timing for the cessation of tobacco use before plastic surgery has not, however, been precisely determined. The aim of this work was to define the ideal duration of nicotine withdrawal prior to random-pattern skin flap surgery in rats. Methods Groups of 11 animals were subcutaneously injected with saline or nicotine (2 mg/kg) twice a day and subjected to random-pattern skin flap surgery according to the following protocol: Group I: continuously injected with saline 4 weeks before and 1 week after the surgery; Group II: injected with nicotine for 4 weeks until the day of the surgery; Group III: injected with nicotine for 4 weeks until one day before the surgery; Group IV: injected with nicotine for 4 weeks until 5 days before the surgery; Group V: injected with nicotine for 4 weeks until 10 days before the surgery; Group VI: continuously injected with nicotine for 4 weeks before and 1 week after the surgery. McFARLANE skin flaps were performed on the dorsal skin, and the rats were sacrificed 1 week after the surgery. Results The necrotic area was smaller in group I (8.85 cm 2) than in group II (12.15 cm 2), III (12.88 cm 2) and VI (14.84 cm 2) (ANOVA p<0.0001). There was no difference between groups I, IV (10.13 cm 2) and V (9.27 cm 2). Conclusions In conclusion, 5 days before surgery was considered the ideal time for nicotine withdrawal in this experimental model.

ATP-Sensitive Potassium Channels Mediate the Anti-Ischemic Properties of Ischemic and Pharmacologic Preconditioning in Rat Random-Pattern Skin Flap

Ischemic preconditioning (IPC) and pharmacologic preconditioning by morphine and adenosine may significantly decrease the amount of necrosis in rat random pattern skin flaps. We examined the role of ATP-sensitive potassium channels (K(ATP) channels) in mediating these protective phenomenon by using glibenclamide a nonspecific blocker of these channels. We also investigated whether administration of diazoxide an opener of the K(ATP) channels could mimic the same protective effect. Ninety male Sprague-Dawley rats were randomly divided into either control or treatment groups (n = 6 each). Bipedicled dorsal skin flaps (2 x 8 cm) were elevated at the midline. In pharmacologic preconditioning groups, 1 mL of morphine (5 mg/flap), adenosine (0.5 mg/flap), or different doses of diazoxide (0.5, 1, 5, and 15 mg/flap) were administered locally in the cranial half of the flap, respectively. One milliliter of saline was locally injected in the control group. In the IPC group, 1 hour after local saline injection the cranial pedicle was clamped for 20 minutes, and then 40 minutes' reperfusion was performed. In another experiment, 0.3 mg/kg of glibenclamide was injected intraperitoneally 30 minutes before local administration of saline or drug in ischemic or pharmacologic preconditioning groups. Regardless of the group, all flaps were cut at the cranial side 2 hours after elevation and were sutured back. Flap survival area was evaluated on the seventh postoperative day. IPC and pharmacologic preconditioning with morphine, adenosine, and diazoxide (in higher doses; 1, 5, and 15 mg/flap) improved survival area compared with the control group. Glibenclamide abolished their protective effect. K(ATP) channels may have a key role in anti-ischemic properties of IPC and pharmacologic preconditioning.

Effect of short-term use of oral smokeless tobacco on random-pattern skin flap survival in rats

We investigated the effects of smokeless tobacco on the survival of random-pattern skin flaps in rats. Twenty rats were divided into two groups (n=10 each). In the experimental group 200 mg smokeless tobacco (Maras powder) (1 mg nicotine) was inserted intraorally once a day for seven days under general anaesthesia. It was not given to the control group, but the rats were similarly anaesthetised with ketamine. On day 8, plasma cotinine concentrations were measured. The random-pattern dorsal skin flaps measuring 3 x 10 cm were then raised and resutured. Percentage survival area was assessed after a further eight days. The mean (SD) survival was 39 (7)% in the experimental, and 65 (8.9)% in the control, groups (p=0.0001). The mean (SD) plasma cotinine concentrations were 124.4 (73) ng/ml and <10 ng/ml, respectively. Smokeless tobacco use increased the incidence of flap necrosis in random-pattern skin flaps in rats.

EFFICACY OF TOPICAL NITROGLYCERIN AND TRANSCUTANEOUS ELECTRICAL NERVE STIMULATION ON SURVIVAL OF RANDOM-PATTERN SKIN FLAPS IN RATS

We compared the efficacy of topical nitroglycerin and transcutaneous electrical nerve stimulation (TENS) on the survival of random-pattern skin flaps in rats. Thirty Wistar albino rats were used and a dorsal, cranially-based random-pattern flap was raised. The rats were divided into three groups of 10 rats each. The first group had only the flap raised while the second and third groups were given topical nitroglycerin 5 mg or TENS for one hour a day for seven days. The amount of flap necrosis was measured on the seventh postoperative day. The mean area of necrosis in the flaps were 726.2, 544.2, and 150.0 mm 2 in the control, nitroglycerin, and TENS groups, respectively. The mean percentage of flaps that necrosed were 51.9, 38.9, and 10.7 in the corresponding groups. The TENS group had significantly higher percentage area of flap surviving than the control (p 3 0.0001) and nitroglycerin groups (p = 0.002). TENS, with its efficacy on survival and with negligible side-effects, could be a reliable treatment. Clinically, it can easily be used postoperatively when flaps become ischaemic, and will be tolerated well by patients.

Ketorolac (Toradol) and Acute Random-Pattern Skin Flap Survival in Rat

To assess the efficacy of sustained postoperative intramuscular ketorolac tromethamine (Toradol) at analgesic levels in the augmentation of acute, random-pattern skin flaps in rat. Prospective, randomized, placebo-controlled, animal trial. Animal research laboratory, School of Medicine, Oregon Health Sciences University, Portland. Forty-four adult male Sprague-Dawley rats (260 to 280 g). Twenty-two treatment animals underwent modified McFarlane random-pattern skin flaps followed immediately by intramuscular loading doses of ketorolac. Treatment animals were then maintained on a regimen of intramuscular ketorolac using a three times a day dosing schedule for 14 days postoperatively. Twenty-two control animals underwent identical modified McFarlane random-pattern skin flaps and were given equivalent volumes of intramuscular saline on the same dosing schedule for the 14-day treatment period. Postmortem measurements of skin flap ischemia (expressed as a percentage of total flap surface area) were performed for both treatment and control animals by three independent, non-blinded observers using the acetate tracing technique. Both pooled and individual data were statistically analyzed using personal computer software. Forty-three of the 44 animals successfully completed the experimental trial. One animal in the treatment group died on postoperative day 3 of unknown causes. During the study period, one postoperative hematoma was detected in both the treatment and control groups. The mean percentage of skin flap ischemic necrosis observed in control animals (35.4%) was consistently less than that measured in the treatment group (36.4%). However, the difference in ischemic flap necrosis between control and treatment groups was not statistically significant (P = .6919). Comparatively high-dose intramuscular ketorolac failed to augment acute, random-pattern skin flap survival in rat when initiated in the immediate postoperative period. Complications of prolonged, intramuscular ketorolac were not observed in this trial. Further studies using preoperative initiation of drug therapy may help to clarify the true efficacy of ketorolac in flap augmentation.