Reliability and Safety of Cross-Leg Free Latissmus Dorsi Muscle Flap in Reconstruction of Mutilating Leg Injuries Using End-to-Side Anastomosis

Abdelmegeed Ahmed Gaber,Hifny Mahmoud A.,Abulezz Tarek A.,Saied Samia,Ellabban Mohamed A.,Abo-Saeda Mohamed Abdel-Al,Allam Karam A.,Haredy Mostafa Mamdoh,Mazeed Ahmed S. 대한성형외과학회 2023 Archives of Plastic Surgery Vol.50 No.5

Background Free tissue transfer is considered the gold standard option for the reconstruction of distal leg defects. Free tissue transfer using recipient vessels in the contralateral leg (cross-leg bridge) is a potential option to supply the flap if there are no suitable recipient vessels in the injured leg. Most studies have described this technique using end-to-end anastomosis which sacrifices the main vessel in the uninjured leg. This study evaluated the use of a cross-leg free latissimus dorsi muscle flap for the reconstruction of defects in single-vessel legs, using end-to-side anastomosis to recipient vessels in the contralateral leg without sacrificing any vessel in the uninjured leg.Methods This is a retrospective study that included 22 consecutive patients with soft tissue defects over the lower leg. All the reconstructed legs had a single artery as documented by CT angiography. All patients underwent cross-leg free latissimus dorsi muscle flap using end-to-side anastomosis to the posterior tibial vessels of the contralateral leg.Results The age at surgery ranged from 12 to 31 years and the mean defect size was 86 cm2. Complete flap survival occurred in 20 cases (91%). One patient had total flap ischemia. Another patient had distal flap ischemia.Conclusion Cross-leg free latissimus dorsi muscle flap is a reliable and safe technique for the reconstruction and salvage of mutilating leg injuries, especially in cases of leg injuries with a single artery. As far as preservation of the donor limb circulation is concerned, end-to-side anastomosis is a reasonable option as it maintains the continuity of the donor leg vessels.

Identification of the Insulin Signaling Cascade in the Regulation of Alpha-Class Glutathione S-Transferase Expression in Primary Cultured Rat Hepatocytes

Kim, Sang K.,A.Abdelmegeed, Mohamed,F.Novak, Raymond 충남대학교 형질전환복제돼지연구센터 2007 논문집 Vol. No.10

We reported previously that insulin elevated alpha-class glutathione S-transferase (GSTs) protein levels in primary cultured rat hepatocytes (Kim et al., 2003b). In contrast, glucagon down-regulated alpha- and pi-class GST expression, and mechanistic research implicated cAMP and protein kinase A in this process (Kim et al., 2003b). The present study examines the signaling pathways involved in the regulation of alpha-class GST in response to insulin in primary cultured rat hepatocytes. Protein levels of GSTA1/2 and GSTA3/5 and activity of GST toward 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole (NBD) were increased in an insulin concentration-dependent manner. Treatment of cells with the phosphatidylinositol 3-kinase (Pl3K) inhibitors wortmannin and LY294002 [2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one) or rapamycin, an inhibitor of mammalian target of rapamycin and ribosomal p70 S6 kinase (p70S6K) phosphorylation, or with an adenovirus containing green fluorescent protein and a dominant-negative and kinase-dead Akt, effectively inhibited the insulin-mediated increase in alphaclass GST expression and GST activity toward NBD. In contrast, PD98059 (2´-amino-3´-methoxyflavone), an inhibitor of mitogen-activated protein kinase kinase, SP600125 (1,9-pyrazoloanthrone), an inhibitor of c-Jun N-terminal kinase, SB203580 [4-(4-fluorophenyl)-2 -(4- methylsulfinylphenyl)-5-(4-pyridyl)1H-imadazole], an inhibitor of p38 mitogen-activated protein kinase, or bisindolylmaleimide, a broad spectrum inhibitor of protein kinase C, did not inhibit the insulin-mediated increase in alpha-class GST protein levels in hepatocytes. These results show that Pl3K/Akt/p70S6K signaling is active in the insulin-mediated up-regulation of the antioxidant defense system and that low insulin levels, as encountered in diabetes, potentially increase the susceptibility of hepatocytes to xeno-biotic-mediated and/or oxidative stress-mediated damage.

THE MITOGEN-ACTIVATED PROTEIN KINASE (MEK) INHIBITOR PD98059 ELEVATES PRIMARY CULTURED RAT HEPATOCYTE GLUTATHIONE LEVELS INDEPENDENT OF INHIBITING MEK

Kim, Sang K.,A. Abdelmegeed, Mohamed,F. Novak, Raymond 충남대학교 형질전환복제돼지연구센터 2007 논문집 Vol. No.10

The antioxidant activity of flavonoids, directly through scavenging oxidizing species and indirectly through modulating drug-metabolizing enzyme activities, is associated with chemopreventive and chemotherapeutic effects. However, little published information is available concerning the effect of flavonoids on glutathione (GSH) homeostasis. We previously demonstrated that PD98059 (2'-amino-3'-methoxyflavone), a flavone derivative and selective mitogenactivated protein kinase kinase (MEK) 1 inhibitor, enhanced the insulin-mediated increase in GSH levels (J Pharmacal Exp Ther 311:99-108). To determine whether the PD98059-mediated increase in GSH levels was associated with MEK inhibition, primary cultured rat hepatocytes were treated with PD98059, the MEK inhibitor U0126, which is not a flavone derivative, or flavone. PD98059 increased GSH levels in a concentration-dependent manner in hepatocytes cultured in the presence or absence of insulin. In contrast, GSH levels were not affected by U0126 at concentrations sufficient to inhibit insulin-mediated extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation. Flavone, however, markedly increased GSH levels without inhibition of ERK1/2 phosphorylation. The concentration of GSH in the culture medium was also elevated by PD98059 or flavone, suggesting that the cellular GSH elevation could not be accounted for by the inhibition of GSH efflux into medium. Interestingly, PD98059 and flavone increased cellular cysteine levels, which may be responsible for the PD98059 and flavone-mediated elevation of GSH levels. These results provide evidence that PD98059 and flavone produce dramatic changes in GSH homeostasis in hepatocytes, through a mechanism(s) unrelated to MEK inhibition. Moreover, the current study implies that flavonoid-induced chemopreventive and chemotherapeutic effects may be mediated by regulation of redox state through the stimulation of GSH synthesis.

Role of mechanical and redox stress in activation of mitogen-activated protein kinases in primary cultured rat hepatocytes

Kim, Sang K.,J.Woodcroft, Kimberley,Oh, Soo Jin,A.Abdelmegeed, Mohamed,F.Novak, Raymond 충남대학교 형질전환복제돼지연구센터 2007 논문집 Vol. No.10

Mechanical stress is known to activate signaling cascades, including mitogen-activated protein kinase (MAPK) pathways. Although mechanical stress has been implicated in hepatic cirrhosis and liver regeneration following hepatectomy, the signaling pathway(s) that may be activated in hepatocytes in response to mechanical stress have not been determined, Using primary cultured rat hepatocytes to examine cellular signaling in response to mechanical stress associated with medium change, we observed that the phosphorylation status of extracellular signal-regulated kinase 1/2 (ERK1/2), Jun N-terminal kinase and p38 MAPK, but not Akt, was altered. MAPK activation, especially ERK 1/2, was rapidly increased within 5 min, followed by a subsequent decrease to below basal levels between 30 min and 1 h following medium change. MAPK/ERK kinase (MEK1/2) phosphorylation followed the same pattern, The phosphorylation of Raf-l in response to medium change was also consistent with Raf-l serving as an upstream regulator of MEK 1/2-ERK1/2 signaling. Phosphorylation of ERK1/2 was increased by mechanical stress alone, suggesting that mechanical stress may be primarily responsible for ERK1/2 activation in response to medium change. Medium change produced a marked decline in oxidized glutathione and malondialdehyde levels, and the antioxidant N-acetyl-L-cysteine decreased basal ERK1/2 phosphorylation. suggesting a role for oxidative stress in maintaining basal ERK1/2 phosphorylation in cultured hepatocytes, These data suggest that medium change results in immediate activation of the MAPK signaling pathway due to mechanical stress, followed by a subsequent inactivation of MAPK signaling due to a reduction in oxidative stress levels. These processes may be associated with alteration of hepatic hemodynamic circulation observed in hepatic diseases and in liver transplantation.