The effect of enalapril on skin flap viability is independent of angiotensin II AT1 receptors

Photobiomodulation effect in tumoral necrosis factor-alpha(TNF-α) on the viability of random skin flap in rats

The aim of this study was to investigate the effect of red laser (660 nm) photobiomodulation (PBM) with different energies on tumor necrosis factor-alpha(TNF-α) expression for random skin flap viability in rats. Twenty-four Wistar rats were divided into three groups: sham group (SG), PBM laser group with an energy dose of 0.29 J (0.29G), and PBM laser group with an energy dose of 7.30 J (7.30G). A cranially based dorsal skin flap measuring 10 × 4 cm was raised and a plastic barrier was placed between the flap and its bed. PBM was applied in 3 timepoints: in the immediate postoperative period, in the 1^st and in the 2^nd postoperative days; the animals were euthanized on the 7^th postoperative day. The assessments included: TNF-α expression of 3 different flap areas (proximal, medial and distal), by immunohistochemistry; percentage of skin flap necrosis area, by the paper template method. The statistical analysis was performed through the Kruskal-Wallis and Mann-Whitney tests, the level of significance adopted was 5% (p < 0.05). TNF-α expression was significantly lower for 7.30G in the proximal area, reduced for SG in the medial point, and larger for 7.30G in the distal area. The percentage of flap necrosis area was significantly reduced for 7.30G. Higher energy doses are more efficacious than lower energy doses for modulating TNF-α expression. PBM with an energy dose of 7.30 J was effective in reducing the expression of TNF-α and increase skin flap viability.

Standardization of the Rat Dorsal Random Pattern (McFarlane) Flap Model and Evaluation of the Pharmacological Agents Aiming to Salvage Partial Flap Necrosis: A Systematic Review and a Meta-analysis

INTRODUCTION

Partial flap necrosis is a common complication after surgery. McFarlane flap model has been used for assessment of various agents' effects on random flap survival. The aim of this study was to review the methodology of studies using this flap model and reveal the most successful agents.

MATERIALS AND METHODS

PubMed, Scopus, and Web of Science databases were screened for words "McFarlane flap," "flap survival," and ("flap" and "rat") by using time limits between 1965 and 2019. A total of 71 original articles were reviewed. Dimensions and base (cranial/caudal) of the flap, treatment protocol, follow-up period, and survival rates were extracted. Modified survival rates were calculated. Coefficients of variation of cranial/caudally based control group flaps and most commonly used flap models were calculated to assess interstudy variability.

RESULTS

A total of 165 different treatment regimens were studied. One-hundred twelve regimens (67.9%) were found to increase flap survival. Most common flap dimensions were 9 cm × 3 cm, followed by 10 cm × 3 cm, 8 cm × 2 cm and 6 cm × 2 cm. Studies using caudally based flaps showed less interstudy variability, but survival rates were similar. Pentoxifylline, sildenafil, chlorpromazine, phenoxybenzamine, and phentolamine were reported to be successful in multiple studies.

CONCLUSIONS

There are numerous agents found to be effective for treatment of partial flap necrosis, but further clinical research is needed. To overcome standardization problems, use of commonly used flap dimensions with a caudal base and interpretation of results after 7 days of follow-up seems appropriate.

Effects of antihypertensive drugs on surgical outcomes of breast reconstruction: a nationwide population-based claim study

Background

Experimental studies have reported that angiotensin receptor blockers (ARBs) increase the risk of surgical complications. However, clinical data on their effect on surgical outcomes are limited. The aim of this study was to investigate the impact of perioperative use of ARBs on the outcomes of breast reconstruction using population-based claim data.

Methods

Data of patients who underwent direct-to-implant or abdomen-based autologous breast reconstruction after total mastectomy from April 2015 to December 2018 were obtained from the Health Insurance Review and Assessment Service database. The patients were categorized as ARB, non-ARB, control, and non-hypertension groups. The effects of ARBs on surgical complications, length of hospital stay, and complication-related medical costs were evaluated.

Results

Of the 9,036 patients who met the inclusion criteria, 5,192 underwent direct-to-implant reconstruction, and 3,844 underwent abdomen-based autologous reconstruction. The length of hospital stay was the longest and the surgical complication rate and complication-related medical cost were the highest in the ARB group after both reconstruction methods. Compared with non-treatment with antihypertensive drugs, ARB use was found to be an independent risk factor for surgical complications in direct-to-implant reconstruction [odds ratio (OR), 1.96; 95% confidence interval (CI), 1.09-3.50; P=0.0237] and complication-related medical cost (OR, 1.93; 95% CI, 1.10-3.40; P=0.0221) in abdomen-based autologous reconstruction.

Conclusions

Perioperative ARB use was associated with adverse postoperative breast reconstruction outcomes. These findings might have a significant impact on perioperative antihypertensive management; nevertheless, further studies are warranted to confirm the study findings.

Postconditioning With Red-Blue Light Therapy Improves Survival of Random Skin Flaps in a Rat Model

BACKGROUND

Random skin flap ischemic necrosis is a serious challenge in reconstructive surgery. Photobiomodulation is a noninvasive effective technique to improve microcirculation and neovascularization. Photobiomodulation with red or blue light has been separately proven to partially prevent skin flap necrosis, but the synergistic effect of red and blue light not been elucidated. Our experiment evaluated the impact of postconditioning with red-blue light therapy on the viability of random flaps.

METHODS

Thirty Sprague-Dawley male rats (male, 12 weeks) with a cranially based random pattern skin flap (3 × 8 cm) were divided into 3 groups: control group, red light group, and red-blue light group. On postoperative day 7, flap survival was observed and recorded using transparent graph paper, flaps were obtained and stained with hematoxylin and eosin, and microvessel density was measured. Micro-computed tomography was used to measure vascular volume and vascular length. On days 0, 3, and 7 after surgery, blood flow was measured by laser Doppler. To investigate the underlying mechanisms, the amount of nitric oxide (NO) metabolites in the flap tissue was assessed on days 3, 5, and 7 after surgery.

RESULTS

The mean percentage of skin flap survival was 59 ± 10% for the control group, 69 ± 7% for the red light group, and 79 ± 9% for the red-blue light group (P < 0.01). The microvessel density was 12.3 ± 1.2/mm2 for the control group, 31.3 ± 1.3/mm2 for the red light group, and 36.5 ± 1.4/mm2 for the red-blue light group (P < 0.01). Both vascular volume and total length in the red-blue light group showed significantly increased compared with the red light and control group (P < 0.01). Blood flow in the red-blue light treated flap showed significantly increased at postsurgery days 3 and 7 compared with the red light and control group (P < 0.01). The level of the NO metabolites was significantly increased in flap tissues belonging to the red-blue light group compared with the other 2 groups (P < 0.01).

CONCLUSIONS

This study showed that postconditioning with red-blue light therapy can enhance the survival of random skin flap by improving angiogenesis and NO releasing.

Rosmarinus Improved Skin Flap Survival Through mTOR Dependent Pathway

Introduction: Skin flap application in the clinical practice is restricted due to the ischemic damage and flap necrosis. Rosmarinus oil has been shown to improve a skin flap survival. In the present work we studied the role of mammalian target of rapamycin (mTOR) signaling on rosmarinus-induced flap protection. Methods: A flap surgery was performed on Sprauge-Dawley rats (8 cm in by 3 cm). A week before and a week after the surgery the flaps were treated with topical rosmarinus oil (twice per day). Rapamycin (m-TOR inhibitor) was administered 30 minutes before the flap surgery in rosmarinus-treated or not treated groups. A week after the surgery the malondialdehyde (MDA) contents, myeloperoxidase (MPO) and superoxide dismutase (SOD) activities, expression of Bax, Bcl-2, mTOR and p-mTOR were measured in the flap tissue. Results: Topical application of the rosmarinus increased the flap survival (p<0.05), anti-oxidative enzyme activity (SOD, p<0.05) and anti-apoptotic protein Bcl-2 expression. Rosmarinus treatment decreased the flap MDA content, MPO activity, and pro-apoptotic protein Bax expression (p<0.05). Rosmarinus topical application did not change mTOR expression and phosphorylation in the flap tissue. Expression of p-mTOR in rosmarinus treated group was suppressed by rapamycin pre-treatment, which also abolished rosmarinus effects on the flap survival (p<0.05). Conclusion: These data suggested p-mTOR dependent mechanism in rosmarinus-induced flap survival.

Effects of Antihypertensive Drugs on Outcomes of Breast Reconstruction

BACKGROUND

Angiotensin receptor blocker (ARB), a commonly used antihypertensive drug, is reported to affect wound healing and flap survival in animal models. However, this has not been elucidated in a clinical series. This study aimed to investigate the impact that perioperative use of ARB has on outcomes after breast reconstruction.

METHODS

Patients who underwent immediate breast reconstruction using a tissue expander or a deep inferior epigastric perforator (DIEP) flap were reviewed. The patients were categorized according to the types of antihypertensive medications as follows: the ARB group consisted of hypertensive patients treated with ARB alone or a combination of ARB and other drugs; the non-ARB group included those receiving drugs other than ARB; and the control group did not receive any medication. The effects of antihypertensive drugs on the development of complications were evaluated.

RESULTS

The study analyzed 1390 cases including 999 cases of tissue-expander insertion and 391 cases of DIEP flap reconstruction. With regard to tissue-expander reconstruction, the rates of seroma, reoperation, reconstruction failure, and overall complications were significantly higher in the ARB group than in the other two groups. Compared with no medication, ARB use was an independent risk factor for these complications. With regard to DIEP flap reconstruction, the ARB group showed a significantly higher rate of fat necrosis and significantly greater odds for the development of overall perfusion-related complications and fat necrosis than the control group after adjustment for other variables.

CONCLUSIONS

Perioperative administration of ARB might be associated with adverse outcomes after breast reconstruction.

Combination therapy profoundly improved skin flap survival by modulating KATP channels and nitric oxide

PURPOSE

A potential therapeutic approach on skin flap necrosis is to target parallel pathways involved in necrosis. Azelaic Acid, Minoxidil and Caffeine combination was tried on skin flap survival by their possible interaction with ATP sensitive potassium (KATP) channels and nitric oxide pathway.

MATERIAL AND METHODS

Sprauge-Dawley rats were divided into 8 groups for skin flap surgery. Azelaic acid, minoxidil, caffeine, or their combination were applied topically in different groups. Two additional groups were treated with L-NAME or glibenclamide in addition to the combination therapy. Percentage of flap necrosis was calculated and flap samples were removed to measure tissue malondialdehyde (MDA) and nitric oxide (NO) and expression of inducible nitric oxide synthase (iNOS), Bcl-2 and Bax proteins.

RESULTS

Combination therapy profoundly decreased skin flap necrosis, tissue MDA contents, and expression of the pro-apoptotic protein Bax (p < 0.05 vs. single treatments). These effects were reversed by L-NAME and glibenclamide pre-treatments. Further evaluations showed combination therapy increases flap tissue NO content and iNOS expression (p < 0.05 vs. single treatments).

CONCLUSION

Beneficial effect of the combination therapy with azelaic acid, minoxidil and caffeine therapy on rescuing the flap from necrosis by targeting parallel signaling pathways suggested potential applications in clinical practice.

Capsaicin protects against testicular torsion injury through mTOR-dependent mechanism

SCOPE

Testicular torsion and subsequent release of reactive oxygen species (ROS) can cause infertility in adults. Oxidative stress following testicular torsion plays an important role in the ýonset and development of apoptotic cell death through dysregulation of the cellular signaling pathways. Anti-inflammatory and antioxidant properties of capsaicin, a bioactive composition present in red peppers, has already been exploited for treatment of the cancer and pain relief. In present work, we evaluated the role of the mammalian target of rapamycin (mTOR) in antioxidant effect of capsaicin against reperfusion injury following testicular torsion.

METHODS

Male Wistar rats weighing 200-220 g were randomly assigned into four major groups: (i) a sham operated group, (ii) a testicular torsion (TT) group, (iii) three groups treated with different doses of capsaicin (TT + 100, 500 and 1000 μg/ml Cap), and (iv) three groups of healthy rats treated with different doses of capsaicin (100, 500 and 1000 μg/ml). Western blotting assay was used to examine the anti-apoptotic effects of capsaicin in testicular cells following torsion. H&E and TUNEL methods were used to evaluate testicular morphology and apoptosis activity.

RESULTS

Compared to control group, phosphorylation of mTOR was significantly increased in the TT groups. Capsaicin administration remarkably decreased the phosphorylation of mTOR at the highest dose (P < 0.05). Capsaicin decreased apoptosis and preserved tubular morphology in testes.

CONCLUSION

Our results showed that antioxidant properties of capsaicin minimizes cell death and reperfusion injury following testicular torsion.

Low-level laser irradiation, cyclooxygenase-2 (COX-2) expression and necrosis of random skin flaps in rats

Skin flaps are still a matter of concern among surgeons, as failures can occur leading to flap necrosis. However, low-level laser irradiation has been reported as an effective tool to improve the viability of ischemic flaps, yet its mechanisms of action remain unclear. We investigated the effect of low-level laser irradiation on the viability of random skin flaps in rats and determined COX-2 expression in the flap pedicle. The study animals comprised 24 EPM-1 Wistar rats which were randomly allocated into three equal groups. A cranially based dorsal random skin flap measuring 10 × 4 cm was created in all the animals. In one group, laser irradiation was simulated (sham group), and in the other two groups the animals were irradiated at 12 points with 0.29 J at 20 mW (energy density 10.36 J/cm(2), irradiance 0.71 W/cm(2)), or with 7.3 J at 100 mW (energy density 260.7 J/cm(2), irradiance 3.57 W/cm(2)). These procedures were applied to the cranial half of the flap immediately after surgery and were repeated on days 2 and 5 after surgery. The percentage necrotic area was determined on day 7 after surgery by the paper template method. The immunohistochemical expression of COX-2 in the samples was given scores from 0 to 3. The necrotic area was smaller in group irradiated at 7.3 J compared to sham-treated group and to the group irradiated at 0.29 J (P < 0.05); there was no difference between the sham-treated group and group irradiated at 0.29 J. COX-2 expression was lower in the group irradiated at 7.3 J than in the sham-treated group and the group irradiated at 0.29 J (P < 0.001). Low-level laser therapy was effective in decreasing random skin flap necrosis in rats using a laser energy of 7.30 J per point. Laser irradiation also decreased the expression of COX-2 in the flap pedicle.