The Effect of Omeprazole Usage on the Viability of Random Pattern Skin Flaps in Rats

Celastrol enhances the viability of random-pattern skin flaps by regulating autophagy through the AMPK-mTOR-TFEB axis

In reconstructive and plastic surgery, random-pattern skin flaps (RPSF) are often used to correct defects. However, their clinical usefulness is limited due to their susceptibility to necrosis, especially on the distal side of the RPSF. This study validates the protective effect of celastrol (CEL) on flap viability and explores in terms of underlying mechanisms of action. The viability of different groups of RPSF was evaluated by survival zone analysis, laser doppler blood flow, and histological analysis. The effects of CEL on flap angiogenesis, apoptosis, oxidative stress, and autophagy were evaluated by Western blot, immunohistochemistry, and immunofluorescence assays. Finally, its mechanistic aspects were explored by autophagy inhibitor and Adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) inhibitor. On the seventh day after surgery, the survival area size, blood supply, and microvessel count of RPSF were augmented following the administration of CEL. Additionally, CEL stimulated angiogenesis, suppressed apoptosis, and lowered oxidative stress levels immediately after elevated autophagy in ischemic regions; These effects can be reversed using the autophagy inhibitor chloroquine (CQ). Specifically, CQ has been observed to counteract the protective impact of CEL on the RPSF. Moreover, it has also been discovered that CEL triggers the AMPK-mTOR-TFEB axis activation in the area affected by ischemia. In CEL-treated skin flaps, AMPK inhibitors were demonstrated to suppress the AMPK-mTOR-TFEB axis and reduce autophagy levels. This investigation suggests that CEL benefits the survival of RPSF by augmenting angiogenesis and impeding oxidative stress and apoptosis. The results are credited to increased autophagy, made possible by the AMPK-mTOR-TFEB axis activation.

Papaverine loaded injectable and thermosensitive hydrogel system for improving survival of rat dorsal skin flaps

Vasospasm during reconstructive microsurgery is a common, uncertain, and devastating phenomena concerning flap survival. Topical vasodilators as antispasmodic agents are widely used to reduce vasospasm and enhance microvascular anastomosis in reconstructive microsurgery. In this study, thermo-responsive hydrogel (CNH) was fabricated by grafting chitosan (CS) and hyaluronic acid (HA) to poly(N-isopropylacrylamide) (PNIPAM). Papaverine, an anti-spasmodic agent, was then loaded to evaluate its effect on rat skin flap survival. Post-operative flap survival area and water content of rat dorsal skin flap were measured at 7 days after intradermal application of control hydrogel (CNHP0.0) and papaverine loaded hydrogel (CNHP0.4). Tissue malondialdehyde (MDA) content and superoxide dismutase (SOD) activity was measured using enzyme linked immunosorbent assay (ELISA) to determine oxidative stress in flaps. Hematoxylin and eosin (H&E) staining and immunohistochemistry (IHC) were performed to evaluate flap angiogenesis and inflammatory markers. Results showed that CNHP0.4 hydrogel could reduce tissue edema (35.63 ± 4.01%), improve flap survival area (76.30 ± 5.39%), increase SOD activity and decrease MDA content. Consequently, it also increased mean vessel density, upregulated expression of CD34 and VEGF, decreased macrophage infiltration, and reduced CD68 and CCR7 expression based on IHC staining. Overall, these results indicate that CNHP0.4 hydrogel can enhance angiogenesis with anti-oxidative and anti-inflammatory effects and promote skin flap survival by preventing vascular spasm.

Activating Parkin-dependent mitophagy alleviates oxidative stress, apoptosis, and promotes random-pattern skin flaps survival

The random-pattern skin flap is a crucial technique in reconstructive surgery and flap necrosis caused by ischemia/reperfusion injury is a major postoperative complication. Herein, we investigated the mechanism of mitophagy induced by Melatonin (ML) and its effect on the survival of skin flaps. Our results demonstrated that ML could activate mitophagy, ameliorate oxidative stress and alleviate apoptosis in Tert-Butyl hydroperoxide solution (TBHP)-stimulated human umbilical vein endothelial cells in vitro. Inhibiting ML-induced mitophagy considerably abolished its protective effects. Moreover, knockdown of Parkin by siRNA inhibited ML-induced mitophagy, and subsequently exacerbated oxidative stress and apoptosis. Further study demonstrated that inhibition of AMPK reversed these protective effects of ML and downregulated the expression of TFEB. In the vivo study, ML effectively promoted flap survival by activating mitophagy and subsequently ameliorating oxidative stress and mitigating apoptosis. These results established that ML is a potent agent capable for increasing random-pattern skin flap survival by activating Parkin-dependent mitophagy through the AMPK-TFEB signaling pathway.

Cold Atmospheric Plasma, Platelet-Rich Plasma, and Nitric Oxide Synthesis Inhibitor: Effects Investigation on an Experimental Model on Rats

The evolution of reconstructive methods for defects of the human body cannot yet replace the use of flap surgery. Research is still preoccupied with the ideal techniques for offering the best chances of survival of the flaps. In our study, we investigated the effects of cold atmospheric plasma (CAP), N-nitro-L-arginine methyl ester (L-NAME), and platelet-rich plasma (PRP) injectable solutions on flap survival using an in vivo model. Twenty-four Wistar rats (four groups) had the McFarlane flap raised and CAP, L-NAME, and PRP substances tested through a single dose subcutaneous injection. The control group had only a saline solution injected. To the best of our knowledge, this is the first study that evaluated a CAP activated solution through injection on flaps. The flap survival rate was determined by clinical examination (photography documented), hematology, thermography, and anatomopathological tests. The image digital analysis performed on the flaps showed that the necrosis area (control—49.64%) was significantly lower for the groups with the three investigated solutions: CAP (14.47%), L-NAME (18.2%), and PRP (23.85%). Thermography exploration revealed less ischemia than the control group on the CAP, L-NAME, and PRP groups as well. Anatomopathological data noted the best degree of angiogenesis on the CAP group, with similar findings on the L-NAME and PRP treated flaps. The blood work did not indicate infection or a strong inflammatory process in any of the subjects. Overall, the study shows that the CAP activated solution has a similar (better) impact on the necrosis rate (compared with other solutions with known effects) when injected on the modified dorsal rat skin flap, and on top of that it can be obtained fast, in unlimited quantities, non-invasively, and through a standardized process.

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.

Pharmacological Effects and Toxicogenetic Impacts of Omeprazole: Genomic Instability and Cancer

Omeprazole (OME) is commonly used to treat gastrointestinal disorders. However, long-term use of OME can increase the risk of gastric cancer. We aimed to characterize the pharmacological effects of OME and to correlate its adverse effects and toxicogenetic risks to the genomic instability mechanisms and cancer-based on database reports. Thus, a search (till Aug 2019) was made in the PubMed, Scopus, and ScienceDirect with relevant keywords. Based on the study objective, we included 80 clinical reports, forty-six in vitro, and 76 in vivo studies. While controversial, the findings suggest that long-term use of OME (5 to 40 mg/kg) can induce genomic instability. On the other hand, OME-mediated protective effects are well reported and related to proton pump blockade and anti-inflammatory activity through an increase in gastric flow, anti-inflammatory markers (COX-2 and interleukins) and antiapoptotic markers (caspases and BCL-2), glycoprotein expression, and neutrophil infiltration reduction. The reported adverse and toxic effects, especially in clinical studies, were atrophic gastritis, cobalamin deficiencies, homeostasis disorders, polyp development, hepatotoxicity, cytotoxicity, and genotoxicity. This study highlights that OME may induce genomic instability and increase the risk of certain types of cancer. Therefore, adequate precautions should be taken, especially in its long-term therapeutic strategies and self-medication practices.

Preemptive treatment with photobiomodulation therapy in skin flap viability

Skin Flap is used in reconstructive plastic surgery. However, complications such as ischemia followed by local necrosis may occur, requiring a new surgical procedure. It is well known that photobiomodulation therapy (PBMT) is an effective technique for improving microcirculation and neoangiogenesis, which contributes positively to the blood supply in the pre and post surgical period. Thus, the objective of the present study was to investigate the effects of preemptive treatment with laser PBMT with different energies on the viability in skin flaps in rats. Sixty-three Wistar rats, male, were randomized into five groups: Control Group (CG) (n = 15): PBMT simulation; Preemptive group 1.1 J laser (GP1) (n = 15): preemptive laser PBMT with 1.1 J of energy per point; Preemptive group 4 J laser (GP4) (n = 15): preemptive PBMT with 4 J of energy per point; Laser group 11 J (G1) (n = 9): PBMT immediately after surgery with 1.1 J of energy per point; Laser group 4 J (G4) (n = 9): TFMB immediately after surgery with 4 J of energy per point. The CG, GP1 and GP4 groups started treatment 72 h prior to surgery and were subdivided into two experimental periods, one of them on the day of the flap and the other along with the other groups on the seventh postoperative day. Three days after the randomization, the animals underwent random skin flap surgery. PBMT was performed with a 660 nm laser at three points. In the first experimental period, a greater number of vessels were found, as well as mast cells in GP1 compared to the CG and greater expression of fibroblast growth factor and vascular endothelial growth factor in the GP1 and GP4 groups compared to the CG. In the second experimental period, GP1 presented a lower percentage of necrotic tissue, a higher number of vessels and a percentage of cells labeled with both VEGF and hypoxia indicible factor alpha (HIF-1α) compared to the CG, FGF in GP1, GP4 and G4 when compared to the CG. Thus, it was concluded that preemptive treatment with PBMT with the application of 1.1 J of energy per point is effective in improving the viability of the skin flap.

Sumatriptan Increases Skin Flap Survival through Activation of 5-Hydroxytryptamine 1b/1d Receptors in Rats: The Mediating Role of the Nitric Oxide Pathway

BACKGROUND

Random pattern skin flaps are applicable for reconstructing any defect in plastic surgery. However, they are difficult to apply because of necrosis. Sumatriptan, a selective 5-hydroxytryptamine 1b/1d agonist, is routinely used to offset acute migraine attacks. Recent studies have suggested that sumatriptan may induce vasodilation at lower concentrations. The authors' aim is to investigate the effect of sumatriptan on skin flap survival and the role of nitric oxide in this phenomenon.

METHODS

Seventy-two male Sprague-Dawley rats were divided into eight groups. Increasing doses of sumatriptan (0.1, 0.3, and 1 mg/kg) were given intraperitoneally to three different groups after dorsal random pattern skin flaps were performed. To assess the exact role of 5-hydroxytryptamine 1b/1d receptors, GR-127935 was administered solely and with sumatriptan. N-ω-nitro-L-arginine methyl ester (L-NAME, a nonselective nitric oxide synthase inhibitor) was used to evaluate any possible involvement of nitric oxide in this study. All rats were examined 7 days later.

RESULTS

The authors' results demonstrated that flap survival was increased by lower doses of sumatriptan compared to a control group for both 0.3 mg/kg (p = 0.03, mean difference = 32, SE = 8) and 0.1 mg/kg (p = 0.02, mean difference = 26, SE = 8). This protective effect was eliminated by coadministration of GR-127935 or N-ω-nitro-L-arginine methyl ester with sumatriptan. Histopathologic studies revealed a significant increase in capillary count and collagen deposition and a decreased amount of edema, inflammation, and degeneration.

CONCLUSIONS

Sumatriptan in lower concentration increases skin flap survival by means of activation of 5-hydroxytryptamine 1b/1d receptors. This effect is mediated through the nitric oxide synthase pathway.

NIR-II Fluorescence Imaging of Skin Avulsion and Necrosis

Skin avulsion is commonly seen in individuals exposed to heavy shearing forces. Subcutaneous tissue detachment and bone fractures usually accompany skin avulsion. Thus, the estimation of the extent of damaged tissue is very important. Currently, the viability of skin and subcutaneous tissue is determined by clinical observations, and these observations always underestimate the true extent of the avulsed skin. Herein, we synthesized an innovative probe, CH1055-GRRRDEVDK (CH1055-GK), which can specifically bind to caspase-3 so as to image skin avulsion and define necrotic regions. Our uptake and binding affinity tests in apoptotic cells and evaluation of the probe ex vivo and in vivo showed that the probe has a strong ability to bind caspase-3 in skin avulsion models and that it vividly detected the necrotic area in avulsed skins. Furthermore, the increased fluorescence intensity of the probe in the avulsed skin showed a larger affected area than that determined by clinical observations in live mice. Consequently, our results indicated that observation of the caspase-3-targeted probe CH1055-GK via NIR-II imaging allowed the clear detection of skin avulsion in subjects, indicating its potential as an imaging tool for the early diagnosis of skin avulsion and the determination of necrotic margins.

An injectable thermosensitive hydrogel for sustained release of apelin-13 to enhance flap survival in rat random skin flap

With the advantage of handy process, random pattern skin flaps are generally applied in limb reconstruction and wound repair. Apelin-13 is a discovered endogenous peptide, that has been shown to have potent multiple biological functions. Recently, thermosensitive gel-forming systems have gained increasing attention as wound dressings due to their advantages. In the present study, an apelin-13-loaded chitosan (CH)/β-sodium glycerophosphate (β-GP) hydrogel was developed for promoting random skin flap survival. Random skin flaps were created in 60 rats after which the animals were categorized to a control hydrogel group and an apelin-13 hydrogel group. The water content of the flap as well as the survival area were then measured 7 days post-surgery. Hematoxylin and eosin staining was used to evaluate the flap angiogenesis. Cell differentiation 34 (CD34) and vascular endothelial growth factor (VEGF) levels were detected by immunohistochemistry and Western blotting. Tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) were assessed by enzyme linked immunosorbent assays (ELISAs). Oxidative stress was estimated via the activity of tissue malondialdehyde (MDA) and superoxide dismutase (SOD). Our results showed that CH/β-GP/apelin-13 hydrogel could not only reduce the tissue edema, but also improve the survival area of flap. CH/β-GP/apelin-13 hydrogel also upregulated levels of VEGF protein and increased mean vessel densities. Furthermore, CH/β-GP/apelin-13 hydrogel was shown to significantly inhibit the expression of TNF-α and IL-6, along with increasing the activity of SOD and suppressing the MDA content. Taken together, these results indicate that this CH/β-GP/apelin-13 hydrogel may be a potential therapeutic way for random pattern skin flap.

Tetramethylpyrazine improved the survival of multiterritory perforator flaps by inducing angiogenesis and suppressing apoptosis via the Akt/Nrf2 pathway

Background: Multiterritory perforator flaps were commonly designed to cover the large soft-tissue defects in reconstructive surgery. But the high risk of partial necrosis in the distal portion of the flaps hindered their clinical application. The purpose of this study was to evaluate the effects of tetramethylpyrazine (TMP) on the survival of the multiterritory perforator flaps and to explore the underlying mechanism.

Materials and methods: Seventy-two Sprague–Dawley rats underwent multiterritory perforator flap procedure and were divided into three groups with 24 each. Flap survival and water content were measured, and the area of angiogenesis and apoptosis in the ischemia skin flaps were assessed on the postoperative day 7. The expressions of angiogenesis-related protein VEGF and apoptosis-related protein Bax, Bcl-2 in each group were detected by Western blotting, which also had been used to assess the expressions levels of Akt, p-Akt, and Nrf2.

Results: Following TMP treatment, the survival area and number of microvessels presented in the skin flaps increased and tissue edema reduced on postoperative day 7. The expressions of angiogenesis-related protein VEGF increased in the TMP treatment group than in the control group. In addition, compared with the control group, TMP inhibited apoptosis, and increased the expression levels of p-Akt, Nrf2 in the areas of ischemia. These effects were reversed by an Akt protein inhibitor LY294002. Similarly, treatment with LY294002 inhibited TMP induced by interfering the Akt/Nrf2 signaling pathway.

Conclusion: These results illustrated that TMP could promote the survival of multiterritory perforator flaps by enhancing angiogenesis and attenuating apoptosis. These were involved in Akt/Nrf2 signaling pathway.

Effects of Normovolemic Hemodilution on Survival of Skin Flaps: An Experimental Study

Background

The aim of this study was to investigate the effects of various ratios of hemodilution on the survival of McFarlane’s skin flaps.

Material/Methods

An experimental study was performed on 42 adult male Wistar rats (weighing 260 to 305 g) allocated to a control group without any volume loss and to 6 study groups with hemodilution ratios of 5%, 10%, 15%, 20%, 25%, and 30%. In all subjects, random-pattern McFarlane’s skin flaps were uniformly elevated and re-sutured to the donor sites. The amount of necrosis was evaluated on the 7^th day postoperatively and compared among the groups.

Results

The amounts of flap necrosis in the groups with 5%, 10%, 15%, and 20% hemodilution ratios were significantly lower than that of the control group (p<0.001). In the 25% and 30% hemodilution groups, although there was less necrosis than in the control group, the differences were not statistically significant. Hematocrit levels, which initially decreased in conjunction with the hemodilution ratios, returned to normal levels on the 7^th day after the operation.

Conclusions

Our results indicated that 20% or less of the total blood volume loss that may be compensated by the normovolemic hemodilution with dextran can improve flap survival.

Impact of groin flap ischemia-reperfusion on red blood cell micro-rheological parameters in a follow-up study on rats

BACKGROUND

Flap hypoperfusion or ischemia-reperfusion (I/R) may occur during preparation-transposition procedures and by postoperative thrombotic complications. Behind the microcirculatory disturbances micro-rheological alterations are also supposed.

OBJECTIVE

We aimed to investigate the groin flap I/R with following-up micro-rheological parameters.

METHODS

Anesthetized rats were subjected to Control or I/R groups. Groin flaps were prepared bilaterally, pedicled on the superficial epigastric vessels. In Control group the flaps were re-sutured after one hour, while in I/R group microvascular clips were applied on the pedicles for 60 minutes, then the flaps were repositioned. Besides daily wound control, before the operation and on the 1st, 3rd, 5th, 7th and 14th postoperative days blood samples were collected for testing red blood cell (RBC) deformability (rotational ektacytometry) and aggregation (light-transmission aggregometry).

RESULTS

RBC deformability significantly worsened by the 3rd-7th postoperative day in I/R group. RBC aggregation enhanced significantly by the 1st day, in I/R group it remained elevated on the 3rd day as well. In a complicated case with unilateral flap necrosis, RBC deformability and aggregation worsening was outlined from its group (base, 1st, 3rd day).

CONCLUSION

Wound healing affected micro-rheological parameters in the early postoperative period. Flap I/R exacerbated the alterations. The parameters markedly worsened in case of flap necrosis.