Biomedical subjects

Fu-Chan Wei

Publications and source records attributed to Fu-Chan Wei.

95 records · Page 6Linked to original sources

PubMed2002

Formation of independently revascularized bowel segments using the rectus abdominis muscle flap: a rat model for jejunal prefabrication.

Reconstruction of the pharyngoesophagus with free jejunal transfer is a major challenge when recipient neck vessels are absent because of previous surgery or irradiation. In such instances, jejunal transfer using a muscle flap as a "vascular carrier" may be a problem-solving alternative. Pretransfer vascularization of the jejunum is achieved by wrapping the muscle flap around the small bowel segment. After a short staging period, the mesenteric pedicle is divided and the bowel segment is transferred up to the neck based on its new blood supply. The objectives of this study were to develop an animal model for prefabricating independently revascularized jejunal segments using the rectus abdominis muscle flap and to determine the minimal time required for independent bowel survival. Twenty-four mature (500-g to 700-g) rats were divided into six experimental groups of four animals each. In each animal, a 1.5-cm segment of proximal jejunum was isolated on two jejunal arteries and wrapped with a superior pedicled rectus abdominis muscle flap. To determine the time of neovascular takeover, the mesenteric pedicles were ligated on postoperative day 2 (group I), day 3 (group II), day 4 (group III), day 5 (group IV), day 6 (group V), and day 7 (group VI). At the time of pedicle ligation, the composite flap was transposed to a new subcutaneous position. Viability of bowel was assessed according to gross appearance and histologic examination 48 hours after transfer. Complete survival of revascularized jejunum in 11 of 12 animals was obtained after pedicle ligation on postoperative day 5 and beyond (p < 0.0001, Fisher's exact test). These bowel segments demonstrated luminal patency, intact pink mucosa, mucus production, and visible peristalsis. Histologic examination showed healthy intestinal epithelium and tissue integration along the serosa-muscle interphase. In contrast, pedicle ligation on day 4 and earlier resulted in varying degrees of bowel necrosis characterized by flattening or ulceration of mucosa (day 4), mucosal sloughing and necrosis of mural musculature (day 3), and complete loss of bowel architecture with lumen obliteration (day 2). These findings suggest that jejunal segments may be independently revascularized with the rectus abdominis muscle flap in the rat model. Complete survival and gross normal bowel function may be obtained without mesenteric perfusion after a minimal time of 5 days.

Abdominal Muscles↗

PubMed2002

Technique and strategy in anterolateral thigh perforator flap surgery, based on an analysis of 15 complete and partial failures in 439 cases.

The free anterolateral thigh flap is becoming one of the most preferred options for soft-tissue defect reconstruction. Between June of 1996 and August of 2000, 672 anterolateral thigh flaps were used in 660 patients in Chang Gung Memorial Hospital. A total of 439 flaps were cutaneous or fasciocutaneous flaps based on musculocutaneous perforators. The analysis of the flap failures was done only in this perforator series. In six cases, no suitable skin vessel was found during the dissection of the flaps. The complete success rate was 96.58 percent (424 of 439). Of the 15 failure cases, eight were complete and seven were partial (10 percent to 60 percent of the flap). Thirty-four flaps were reexplored, and 19 (56 percent) were salvaged. In this study, some of the reasons for the flap failure, unique to the anterolateral thigh perforator flap, were identified. They include inadvertent division of perforator at the fascial plane as a result of inadequate knowledge of perforator anatomy, inadvertent injury to the perforator during intramuscular dissection (noted by the surgeon or ignored) as a result of inexperience, and twisting of the pedicle during inset of the flap at the recipient site. Technical pearls in the harvest of the anterolateral thigh perforator flap are as follows: mapping of the skin vessels with a Doppler probe before flap design, meticulous dissection of the perforator under surgical loupe or even lower-magnification microscope, inclusion of a small fascia cuff around the perforator, and intermittent topical use of Xylocaine during the intramuscular dissection of the perforators. During reexploration, one must search for twisting of the pedicle and small bleeders from the branches of the intramuscular perforators.

Adolescent↗

PubMed2002

Basic principles on toe-to-hand transplantation.

Within the last three decades, toe-to-hand transplantation has become a well-established method for function and appearance reconstruction after trauma and in congenital hand anomalies. An otherwise healthy and cooperative patient is the ideal candidate for toe transplantation after trauma. In such patient, even primary toe transplantation is possible, if the stump is clean and viable. If secondary reconstruction after completed wound healing is considered, emphasis should be laid on tissue sacrifice during the acute management of non-replantable amputations at the hand. Specific considerations regarding selection of toe(s) to be transplanted, technique of toe harvest and inset, sequence of transplantations if more than one digit is to be reconstructed such as in the metacarpal hand, and postoperative regimen are important to achieve satisfying functional and aesthetic results on both recipient and donor sites. A trimmed great toe is ideal for thumb reconstruction if the amputaiton is located at or distal to the middle metacarpal shaft. However, in more proximal amputations a second toe may be more suitable as it allows transmetatarsal harvest without increasing donor site morbidity. Distal finger reconstruction with partial toe or second toe warp around flap gives most gratifing result to those patients who are critically concerned about their body images and also those who need distal fingers for jobs or recreation activities. Combined second and third toe or third and fourth toe transplantations are particular useful in metacarpal hand reconstruction to provide tripod pinch. The role of toe-to-hand transplantation in the new millenium assuming progress in tissue engineering, gene transfer, and the development of new immunosuppressive drugs is discussed.

Amputation, Traumatic↗

PubMedDate not supplied

Ischemic preconditioning ameliorates microcirculatory disturbance through downregulation of TNF-alpha production in a rat cremaster muscle model.

Ischemia-reperfusion (I/R) injury is a complex process involving the generation and release of inflammatory cytokines, and the accumulation and infiltration of neutrophils and macrophages, which disturbs the microcirculatory hemodynamics. Nonetheless, ischemic preconditioning (IPC) is known to produce immediate tolerance to subsequent prolonged I/R insults, although its underlying mechanism largely remains unknown. Our study investigated the role of the IkappaB-alpha-NF-kappaB-TNF-alpha (tumor necrosis factor-alpha) pathway in IPC's ability to ameliorate I/R-induced microcirculatory disturbances in rat cremaster muscle flaps. Male Sprague-Dawley rats were randomized (n = 8 per group) into 3 groups: a sham-operated control group, an I/R group (4 h of pudic epigastric artery ischemia followed by 2 h of reperfusion), and an IPC+I/R group (3 cycles of 10 min of ischemia followed by 10 min reperfusion before I/R). Intravital microscopy was used to observe leukocyte/endothelial cell interactions and quantify functional capillaries in cremaster muscles. I/R markedly increased the number of rolling, adhering, and migrating leukocytes. It was also observed that I/R significantly increased TNF-alpha expression in these injured tissues. On the other hand, IPC prevented I/R-induced increases in leukocyte rolling, adhesion, and transmigration. Moreover, TNF-alpha protein production and its mRNA expression were downregulated in the IPC group. Finally, I/R-induced IkappaB-alpha phosphorylation and NF-kappaB (p65) nuclear translocation were both suppressed by IPC. These results indicated that IPC attenuated NF-kappaB activation and subsequently reduced TNF-alpha expression, which resulted in the amelioration of microcirculatory disturbances in I/R-injured cremaster muscles.

Active Transport, Cell Nucleus↗

PubMedDate not supplied

Vastus lateralis muscle flap used for reconstruction of the maxilla after radical resection of recurrent ameloblastoma.

Maxillary ameloblastoma is a benign odontogenic neoplasm. Excision should involve wide margins because of its high recurrence rate and, ideally, be followed by reconstruction. A 23 year-old female patient presented with recurrent ameloblastoma. Two years previously, she had undergone a curettage excision. The recurrent lesion was managed by a total maxillectomy including inferior orbital rim. Simultaneous reconstruction was performed with an iliac crest bone graft for the orbital floor, and a vastus lateralis muscle flap for obliteration of the maxillary sinus and repair the oral and nasal cavities. The transferred vastus lateralis muscle already had spontaneous mucosalization over its surface two weeks after surgery. Postoperative follow up after fourteen months revealed no recurrence and no diplopia. The patient was satisfied with her appearance. The use of a single vastus lateralis muscle flap to repair both oral and nasal cavities is advantageous. It helps avoid hyper-nasal speech and maintain the stability of removable partial dentures. The conventional iliac bone graft supported by a well vascularized muscle eventually survived and provided a good functional and cosmetic result.

Adult↗