Yimin Chai

The linker region of Smad2 mediates TGF-β-dependent ERK2-induced collagen synthesis

Transforming growth factor (TGF)-beta1 can cause fibrosis diseases by enhancing production of collagen. However, the intracellular signaling mechanism for TGF-beta1 stimulation of this process has not been fully elucidated. The present study focused on this mechanism and the cross-talk between the MAPK and Smad pathways. Extracellular signal-regulated kinase (ERK)2 ablation by a small interfering RNA led to marked inhibition of TGF-beta1-induced collagen synthesis and enhanced phosphorylation of the Smad2 linker site in NIH/3T3 fibroblast cells. However, ERK1 ablation had minimal effects. Ablation of either ERK2 or ERK1 had no effect on the phosphorylation of the Smad2 C-terminal site. Furthermore, a Smad2 mutant with reduced phosphorylation of the Smad2 linker site inhibited TGF-beta1-induced collagen synthesis. These results indicate that ERK2, rather than ERK1, plays a predominantly positive role in TGF-beta1-induced collagen synthesis, and that ERK2 enhances collagen synthesis, at least partially, through activation of the Smad2 linker site.

The Extended Peroneal Artery Perforator Flap for Lower Extremity Reconstruction

The peroneal artery perforator flap and its modifications have been widely used for coverage of soft tissue defects of ankle and foot in the past decade. In this article, we report on a series of upper knee, ankle, and foot reconstructions with a proximally or distally based extended peroneal artery perforator (EPAP) flap supplied by distinct perforating branches off the proximal or distal peroneal artery. Total pedicle length obtained ranged from 6 to 12 cm. Twelve patients with soft tissue defects of the lower extremity underwent reconstruction using the EPAP flap. The flaps were designed with the sizes from 10 × 6 cm to 25 × 15 cm. All 12 flaps survived completely without complications. Our experience demonstrates that the EPAP flap is reliable and versatile and can provide a large amount of soft tissue for coverage of defects in the leg anywhere from knee to forefoot obviating the need for free tissue transplantation.

Combined medialis pedis and medial plantar fasciocutaneous flaps based on the medial plantar pedicle for reconstruction of complex soft tissue defects in the hand

The reconstruction of complex soft tissue defects in hands remains a difficult challenge in reconstructive surgery. In this report, we introduce a combined medialis pedis and medial plantar fasciocutaneous flaps supplied by the lateral and medial branches of the medial plantar artery, which allows a one‐stage reconstruction of multiple soft tissue defects in hand. Three combined medialis pedis and medial plantar fasciocutaneous flaps were transferred for repair of the soft tissue defects including palmar and dorsal areas of hand, thumb pulp, and the dorsum of index finger in three patients. All three flaps survived uneventfully with coverage matching the texture and color of the recipients. The donor sites healed without complication. The experience from these cases proves that the combined medialis pedis and medial plantar fasciocutaneous flaps based on the medial plantar pedicle would be a valuable alternative for the reconstruction of complex soft tissue defects in the hand.

Distally based saphenous neurocutaneous perforator flap combined with vac therapy for soft tissue reconstruction and hardware salvage in the lower extremities.

The complex wound with the exposed hardware and infection is one of the common complications after the internal fixation of the tibia fracture. The salvage of hardware and reconstruction of soft tissue defect remain challenging. In this report, we presented our experience on the use of the distally based saphenous neurocutaneous perforator flap combined with vacuum‐assisted closure (VAC) therapy for the coverage of the soft tissue defect and the exposed hardware in the lower extremity with fracture. Between January 2008 and July 2010, seven patients underwent the VAC therapy followed by transferring a reversed saphenous neurocutaneous perforator flap for reconstruction of the wound with exposed hardware around the distal tibia. The sizes of the flaps ranged from 6 × 3 cm to 15 × 6 cm. Six flaps survived completely. Partial necrosis occurred in one patient. There were no other complications of repair and donor sites. Bone healing was achieved in all patients. In conclusion, the reversed saphenous neurocutaneous perfortor flaps combined with the VAC therapy might be one of the options to cover the complex wound with exposed hardware in the lower extremities.

Effect of celecoxib on proliferation, collagen expression, ERK1/2 and SMAD2/3 phosphorylation in NIH/3T3 fibroblasts

In the present study, the effects of celecoxib on proliferation, collagen expression, ERK1/2 and SMAD2/3 phosphorylation in NIH/3T3 fibroblasts were investigated. NIH/3T3 fibroblasts stimulated with fibroblast growth factor-2 (FGF-2) or transforming growth factor-β1 (TGF-β1) were examined in the presence of celecoxib. Proliferation was assessed by MTT assays; ERK1/2 expression and SMAD2/3 expression were assessed by quantitative RT-PCR and western blotting; ERK1/2 phosphorylation and SMAD2/3 phosphorylation were assessed by western blot analysis. The results indicated that celecoxib could suppress cell proliferation stimulated by FGF-2 (IC(50) FGF+group, 75±1.9μmol/l) and TGF-β1 (IC(50) TGF+group, 48±1.4μmol/l), by inhibiting ERK1/2 phosphorylation but not ERK1/2 expression. Celecoxib also suppressed collagen expression (0.35-fold COL3 and 0.43-fold COL1 at 320μmol/l celecoxib relative to the untreated control after stimulation with TGF-β1 for 3h, P<0.01), by inhibiting SMAD2/3 phosphorylation but not SMAD2/3 expression. The suppression of NIH/3T3 fibroblast proliferation and collagen expression upon stimulation by FGF-2 and TGF-β1 is likely a result of the inhibition of ERK1/2 and SMAD2/3 phosphorylation by celecoxib.

Fingertip replantation at the eponychial level with venous anastomosis: an anatomic study and clinical application:

We present an anatomic study of the vein distribution at the eponychial level, in order to standardize outpatient fingertip replantation. The cross sectional anatomy of 100 fingers was studied by dissection following dye injection. The distribution of the veins >0.3 mm was recorded on a pie-chart. Thirty fingers in 27 patients with fingertip amputations at the eponychial level were replanted by anastomosis of the palmar subcutaneous veins, to reconstruct the venous reflux of the amputated digits. The operations were aided by the anatomical study and confirmed that the palmar area is the preferred site for venous anastomosis Following a distal finger amputation at the level of the eponychial fold we propose starting the search for veins between the 3 to 5 o’clock or 7 to 9 o’clock positions, as these are the areas where there are most likely to be suitable veins.

Distally based extended peroneal artery septocutaneous perforator cross-bridge flap without microvascular anastomoses for reconstruction of contralateral leg and foot soft tissue defects.

A cross-leg or cross-bridge free flap is one of the choices for the reconstruction of serious leg soft tissue defects. Here, we report on six cases of leg and foot reconstruction with a distally based extended peroneal artery septocutaneous perforator cross-bridge flap without microvascular anastomoses. The vascular pedicle includes the peroneal artery, its perforator branch, and concomitant veins. The total pedicle length ranges from 10 to 14 cm, and the size ranges from 18 x 8 to 21 x 10 cm. All flaps survived completely without complications. Compared with a cross-leg or cross-bridge free flap, a distally based extended peroneal artery septocutaneous perforator cross-bridge flap without microvascular anastomoses does not require the use of some instruments or techniques for microsurgery, leading to a shorter operation duration and a lower risk of thrombosis in the vessel because microvascular anastomosis is not required.

One-stage reconstruction of complex lower extremity deformity combining Ilizarov external fixation and sural neurocutaneous flap.

BackgroundComplex lower extremity deformities include multidirectional foot and ankle deformities, which are complicated therapeutic and surgical challenges. Correction often requires several stages, which is time consuming and costly. The need to restore the physical, mechanical, and cosmetic aspects of the lower extremity results in a difficult balancing act between these concerns and the deformity correction and soft tissue reconstruction. MethodsBetween January 2009 and September 2011, we treated 5 patients with multidirectional foot and ankle deformities. Significant mobility limitation was caused by abnormal scarring, which led to abnormal gait and weight-bearing regions. We used a sural neurocutaneous flap to repair the soft tissue defects after scar-tissue removal in all patients and placed a circular hinged Ilizarov external fixator for gradual correction. ResultsAll the flaps survived and resulted in good texture match and contour. The follow-up period was 19 to 26 months. The correction lasted 3 to 5 months, and all of the patients were able to walk with satisfactory gaits and without assistance. We encountered no complications, such as pin-track infection or drop foot in our series. ConclusionOur approach, combining a sural neurocutaneous flap and Ilizarov external fixation, was a reliable and effective tool for one-stage reconstruction of complex lower extremity deformities.

One-stage reconstruction of composite extremity defects with a sural neurocutaneous flap and a vascularized fibular graft: a novel chimeric flap based on the peroneal artery

Background: The fibula flap has been widely used for reconstruction of composite bone and soft-tissue defects. The skin paddle of the fibula flap has played a critical role in providing a cutaneous component and good monitor for the bone component. In this report, the authors designed a perforator-based sural neurocutaneous flap instead of a peroneal perforator flap to enlarge a skin paddle for wound coverage. Methods: A novel chimeric flap was harvested based on the peroneal artery, and consisted of a sural neurocutaneous flap and a fibular graft. The sural neurocutaneous flap was elevated based on a single peroneal perforator and connected with the bone component by means of the peroneal artery. Two patients with complex bone and soft-tissue defects were treated by using this chimeric flap. In case 1, the radius defect was 8 cm in length and the soft-tissue defect measured 23 × 10 cm. In case 2, the distal radius was injured and the defect was 16 cm in length. The area of soft-tissue defect was 23 × 8 cm. In this case, the fibula head was used for wrist reconstruction. The soft-tissue defects in the two cases stretched across the palmar and dorsal surfaces of the forearm. Results: The lengths of the bone components were 10 and 16.5 cm, respectively, and the areas of the skin components were 24 × 12 cm and 25 × 10 cm, respectively. Both chimeric flaps survived completely without complications. The follow-up period was 42 months in case 1 and 16 months in case 2. Complete bone union was observed in both cases, and no remarkable degeneration of the fibular head occurred in case 2. The sural neurocutaneous flap showed good texture match and contour. No serious donor-site complications occurred. The two patients were satisfied with their daily lives relative to the severity of their injuries. Conclusion: The chimeric flap composed of a sural neurocutaneous flap and a fibular graft by means of the peroneal artery is a good candidate for reconstruction of long bone defects associated with extensive soft-tissue defects in the extremities. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, V.

Distally based posterior tibial artery cross-bridge flap for reconstruction of contralateral leg soft tissue defects.

A cross-leg or cross-bridge free flap is frequently used for the reconstruction of leg defects in cases with no suitable recipient vessels in the vicinity of the defect. Here we report eight cases of leg reconstruction with a distally based posterior tibial artery cross-bridge flap without microvascular anastomosis technology. A distally based posterior tibial artery flap was elevated and used to reconstruct contralateral leg defects. A skin incision was made near the recipient wound to create a skin bridge, and a subcutaneous tunnel was made between the skin incision and the recipient wound for the vascular pedicle to pass over. All flaps survived completely without complications, except for a case with minor erosion in the donor site. Compared with a cross-leg or cross-bridge free flap, a distally based posterior tibial artery cross-bridge flap is reliable and versatile, leading to shorter operation duration and a lower risk of thrombosis in the vessel because microvascular anastomosis is not required.