Effects of bradykinin on the survival of multiterritory perforator flaps in rats

Bradykinin-bradykinin receptor (B1R) signalling is involved in the blood-brain barrier disruption in moyamoya disease

Moyamoya disease (MMD) is a rare disorder of the cerebrovascular system. It is a steno-occlusive disease that involves angiogenesis and blood-brain barrier (BBB) disruption. Bradykinin (BK), its metabolite des-Arg9-BK, and receptor (B1R) affect angiogenesis and BBB integrity. In this study, we aimed to investigate the changes in BK, B1R and des-Arg9-BK levels in the serum and brain tissues of patients with MMD and explore the underlying mechanism of these markers in MMD. We obtained the serum samples and superficial temporal artery (STA) tissue of patients with MMD from the Department of Neurosurgery of the Jining First People's Hospital. First, we measured BK, des-Arg9-BK and B1R levels in the serum of patients by means of ELISA. Next, we performed immunofluorescence to determine B1R expression in STA tissues. Finally, we determined the underlying mechanism through Western blot, angiogenesis assay, immunofluorescence, transendothelial electrical resistance and transcytosis assays. Our results demonstrated a significant increase in the BK, des-Arg9-BK and B1R levels in the serum of patients with MMD compared to healthy controls. Furthermore, an increase in the B1R expression level was observed in the STA tissues of patients with MMD. BK and des-Arg9-BK could promote the migratory and proliferative abilities of bEnd.3 cells and inhibited the formation of bEnd.3 cell tubes. In vitro BBB model showed that BK and des-Arg9-BK could reduce claudin-5, ZO-1 and occluding expression and BBB disruption. To the best of our knowledge, our results show an increase in BK and B1R levels in the serum and STA tissues of patients with MMD. BK and Des-Arg9-BK could inhibit angiogenesis, promote migratory and proliferative capacities of cells, and disrupt BBB integrity. Therefore, regulating BK, des-Arg9-BK and B1R levels in the serum and the brain could be potential strategies for treating patients with MMD.

Effects of Distal Arterial Supercharging and Distal Venous Superdrainage on the Survival of Multiterritory Perforator Flaps in Rats

BACKGROUND

Which one of the two measures, distal arterial supercharging (DAS) and distal venous superdrainage (DVS), is better to enhance flap survival? No consistent conclusions have been reached.

METHODS

All flaps were pedicled on the deep circumflex iliac vessels. Seventy-two healthy male rats were distributed to four groups randomly: DAVS group (distal arteriovenous supercharging group), the thoracodorsal (TD) artery and TD vein were preserved; DAS group (distal arterial supercharging group), the TD vein was ligated; DVS group (distal venous superdrainage group), the TD artery was ligated; control group, the TD artery and TD vein were ligated. Flap survival rate was evaluated on postoperative day 7. Flap angiography was performed to assess vascular changes of the flap. Microvascular density (MVD) was evaluated by hematoxylin and eosin staining, and CD34-positive microvessel density was measured by immunohistochemistry. Vascular endothelial growth factor (VEGF) level was measured by western blot. The levels of superoxide dismutase (SOD) and malondialdehyde (MDA) were evaluated using specialized commercial kits.

RESULTS

The mean flap survival rate was increased significantly in DAVS and DAS groups than in DVS and control groups. DAVS and DAS groups had higher flap vascularization, MVD, CD34-positive microvessel density, VEGF expression and SOD level compared to DVS and control groups. DAVS and DAS groups also had lower MDA level relative to DVS and control groups.

CONCLUSION

DAS is more conducive to improving the survival rate of the multiterritory perforator flap compared to DVS, mainly by enhancing angiogenesis and preventing ischemia-reperfusion (I/R) injury.

Remimazolam alleviates neuropathic pain via regulating bradykinin receptor B1 and autophagy

OBJECTIVES

Neuropathic pain (NP) represents a broad scope of various pathological ramifications of the nervous system. Remimazolam is a proved sedative in treating neuropathic pain. Considering the Bradykinin receptor's vital role and the potentials of Bradykinin receptor B1 (BDKRB1) in the neuropathic pain-signalling pathway, we nominated them as a primary target for remimazolam.

METHODS

In this study, rats were injected with complete freund's adjuvant (CFA) to construct NP models in vivo. BV2 microglia cells were treated with LPS to establish NP model in vitro. qRT-PCR, ELISA, western blot and immunofluorescence were applied to determine gene expression.

KEY FINDINGS

Our findings revealed that BDKRB1 was overexpressed in NP models in vivo, while R715 (an antagonist of BDKRB1) suppressed the levels of BDKRB1 and inhibited the hyperpathia induced by spinal nerve litigation surgery. Moreover, remimazolam inactivated BDKRB1 signalling via suppressing NF-κB translocation and decreased the release of pro-inflammatory cytokines. Additionally, remimazolam suppressed the translocation of NF-κB, and inhibited autophagic lysosome formation in vivo and in vitro. However, R838 (an agonist of BDKRB1) reversed the effects of remimazolam.

CONCLUSIONS

Remimazolam downregulated BDKRB1, inhibited BDKRB1/RAS/MEK signalling pathway and regulated the autophagic lysosome induction, exhibiting a better outcome in the NP.

Effects of oxidative stress and apoptosis on vascularity and viability of perforator flaps

We investigated lateral thoracic and posterior thigh perforator flaps for viability, vascularization, perfusion and apoptosis in a rat model. Wistar albino rats were divided into six groups: lateral thoracic artery perforator flap (LTPF) sham, 3 × 2 cm² LTPF, 3 × 6 cm² LTPF, posterior thigh perforator flap (PTPF) sham, 3 × 2 cm² PTPF, and 3 × 6 cm² PTPF. Flap viability was determined on postoperative days 1 and 7. On day 7, flaps were photographed and their viability was measured using two-dimensional planimeter paper. Tissue samples were harvested for examination by histology and immunohistochemistry. Viability differences were statistically significant. Epithelial thickness, vascularity and number of fibroblasts were reduced in the 3 × 6 cm² groups. Neovascularization and apoptosis based on molecular tests were not significantly different among groups. Flap size and location are important factors for closure of surgical or traumatic defects. We suggest that for clinical application, wound complications will occur less frequently with perforators that nourish large areas of flaps.

Comparison of arterial supercharging and venous superdrainage on improvement of survival of the extended perforator flap in rats

BACKGROUND

Arterial supercharging and venous superdrainage have been the commonly used vascular augmentation techniques for resolving partial loss of flaps in reconstructive surgery. It remains controversial which one of them is more effective in improving flap survival. The purpose of this study was to compare the effect of distal venous superdrainage and arterial supercharging on the survival of an extended dorsal perforator flap in rats.

MATERIALS AND METHODS

Sixty Sprague-Dawley rats were randomly divided into three groups (n = 20 in each group). An extended dorsal perforator flap with the size of 3 × 12 cm based on the deep circumflex iliac artery and vein was elevated in each rat. In arterial supercharging group, the thoracodorsal artery was retained as the distal supercharging vessel; In venous superdrainage group, the thoracodorsal vein was retained as the distal superdrainage vessel. In control group, no other arteries and veins were retained except the main vascular pedicle. On the seventh day after operation, the survival area of flap was calculated as a percentage of viable area to the total flap. Vascular changes in the choke zones were assessed by angiography. Microvascular density and diameter were assessed via immunohistochemistry staining of CD31 on the fifth day after operation.

RESULTS

The flap survival area in arterial supercharging group was significantly higher than that in venous superdrainage group (98.9 ± 0.8% vs. 81.5 ± 3.5%, p < .001). By gross observation, the extent of dilation of choke zone vessels in venous superdrainage group was smaller compared with that in arterial supercharging group. The density of CD31-positive vessels and the diameter of choke zone vessels in arterial supercharging group were significantly larger than that in venous superdrainage group (23.4 ± 4.6 mm^-2 vs. 13.1 ± 4.2 mm^-2 , p < .05; and 37.5 ± 5.8 μm vs. 27.8 ± 4.9 μm, p < .05).

CONCLUSION

Compared with venous superdrainage, distal arterial supercharging in the potential territory resulted in better survival of an extended dorsal perforator flap in a rat model.