Peihua Cai

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 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.

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.