Effects of nebivolol on skin flap survival: A randomized experimental study in rats

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.

Effect of cilostazol in experimental model of degloving injuries in rat limbs

PURPOSE

To evaluate the effect of the cilostazol on the evolution of partially avulsed flaps, using experimental model of cutaneous degloving in rat limbs.

METHODS

A controlled and randomized experimental study was carried out in which the blood flow and the percentage of flap necrosis were evaluated. We compared the study group, which received cilostazol, and the control group, which received enteral saline solution in the postoperative period. The blood flow in the flap was evaluated through Laser Doppler flowmetry, and a planimetry using the IMAGE J® software was employed for the calculation of the area of necrosis.

RESULTS

Enteral administration of cilostazol was associated with a higher mean blood flow in all regions of the flap, with a statistically significant difference in the proximal and middle regions (p<0.001) and a lower percentage of necrotic area in the flap (p<0.001).

CONCLUSION

Postoperative enteral administration of cilostazol increased blood flow and decreased the total area of necrosis of avulsed cutaneous flaps of rat limbs.

Nebivolol attenuates oxidative stress and inflammation in a guinea pig model of ovalbumin-induced asthma: a possible mechanism for its favorable respiratory effects

An experimental model of ovalbumin (OVA) induced asthma was used to assess the effects of nebivolol, the third-generation selective β₁-adrenergic receptor blocker, on airway reactivity, lung inflammation, and oxidative stress markers. The asthma induction protocol was done by OVA sensitization and challenge. Guinea pigs were classified into control, asthmatic, or asthmatic receiving nebivolol either 7.5 or 15 mg·kg^-1·day^-1 orally. At the end of the study respiratory, the anti-inflammatory and antioxidative effects of nebivolol were assessed. The asthmatic group exhibited a significant increase in early and late airway resistance, airway hyperreactivity to histamine, total and absolute leucocytic count, tumor necrosis factor-α, and interleukin-6 in bronchoalveolar lavage fluid and lung lipid peroxidation and a significant decrease in superoxide dismutase and glutathione compared to the control group. Additionally, there was a significant decrease in lung endothelial nitric oxide synthase (eNOS) and a significant increase in inducible nitric oxide synthase (iNOS) mRNA expression compared to the control group. The high dose of nebivolol counteracted the increased airway resistance induced by OVA, whereas it had no effect on airway hyperresponsiveness. Moreover, nebivolol exhibited significant anti-inflammatory and antioxidant effects and restored the altered levels of eNOS and iNOS compared to the asthmatic group. Collectively, these results suggest a beneficial effect of nebivolol in asthma.

Effect of Systemic Antioxidant Allopurinol Therapy on Skin Flap Survival

BACKGROUND

It has been reported that systemic administration of allopurinol improves cell survival. This study was aimed to evaluate effects of allopurinol on skin flaps in dogs.

METHODS

Twenty dogs underwent one skin flap surgery with a 2-week interval. The first procedure was performed according to the standard protocols. The second phase was started by a 1-week pretreatment with allopurinol. Length of the necrotic zone was measured and recorded daily. At each phase, flaps were removed and sent for histopathological study after 1 week observation.

RESULTS

Mean length of the necrotic zone in allopurinol treated skin flaps has been significantly less than normal flaps over all 7 days of observation (p<0.0001). Histopathology study showed less inflammation and more normal tissue structure in the allopurinol treated skin flaps.

CONCLUSION

It was demonstrated that systemic administration of allopurinol significantly improved skin flap survival.

Relationship between serum fibronectin levels and carnitine administration: an experimental study in rats

We aimed to investigate the relationship between dorsal flap viability and serum fibronectin levels in carnitine-administered rats. A total of 24 rats were equally divided into three groups and operated on. Group 1 (sham group n = 8): following surgery, no agent was given. Group 2 (control group, n = 8): following surgery, sterile saline solution at 0·9% with a dose of 100 mg/kg per day for 7 days was administered intraperitoneally. Group 3 (study group, n = 8): following surgery, carnitine with a dose of 100 mg/kg per day for 7 days was administered intraperitoneally. The flap model used was a 10 × 3 cm dorsal flap extending from the tip of the scapula to the hip joint. This was elevated, and then sutured back to its original site. At the end of postoperative day 8, the animals were anaesthetised and blood samples were collected from intracardiac space. Then, the animals were euthanised. Flap viability was then evaluated measuring the surviving area, using a transparent graph paper. Finally, excised tissue was examined histopathologically. The percentages of viable areas in groups 1, 2 and 3 were 64·68 ± 3·37%, 67·35 ± 5·82% and 75·15 ± 3·56%, respectively. The mean value of fibronectin levels in groups 1, 2 and 3 were 22·3 ± 3·5, 23·1 ± 3·5 and 31 ± 6·8 mg/dl, respectively. The results of this study demonstrated that 100 mg/kg carnitine administration led to an increase in flap viability, and increased serum fibronectin levels might have a role in this process.