Biomedical subjects

W C Lineaweaver

Publications and source records attributed to W C Lineaweaver.

At least 37 records · Page 2Linked to original sources

PubMed2000

The effects of VEGF on survival of a random flap in the rat: examination of various routes of administration.

The purpose of the present study was to determine the effects of vascular endothelial growth factor (VEGF) on survival of a full thickness random pattern, McFarlane musculocutaneous flap in the rat. In addition, this study examined a number of different methods of VEGF delivery in an attempt to determine the most effective route of administration. A 2 x 8 cm full thickness dorsal flap with the pedicle remaining attached at the anterior end was elevated in 72 male Sprague-Dawley rats. The rats were randomised into six groups and immediately received the following treatment: Group I (n = 12): systemic VEGF injection into the femoral vein (50 microg/ml); Group II (n = 10): multiple systemic VEGF injections at 0, 24 and 48 h post flap elevation (50 microg/ml); Group III (n = 12): subdermal VEGF injection into the flap (1 microg/ml); Group IV (n = 12): subfascial VEGF injections into the recipient bed (1 microg/ml); Group V (n = 10): topical VEGF onto the recipient bed (1 microg/ml); Group VI (n = 16): control group with no treatment. Following 5 days recovery, the area of flap survival was measured. Mean flap survival ranged from 91% in Group II to 78% in Group V, and was significantly greater in all experimental groups (P< 0.001 for Groups I-IV and P< 0.05 for Group V) as compared to the control group (mean survival of 66%). The only significant difference between the experimental groups was between the mean survival in Group II and Group V (P< 0. 05). Histological analysis demonstrated a qualitatively greater amount of granulation tissue and neovascularisation in the experimental groups. These results support the notion that VEGF rescues tissue at risk of hypoxic damage by inducing angiogenesis, and the use of growth factors such as VEGF holds promise as a method of increasing skin viability.

Administration, Topical↗

PubMed2000

Free microvascular transfer of the acromiotrapezius osteomuscular flap in rats.

The acromiotrapezius-scapular spine osteomuscular flap is a new osteomuscular research model for use in microvascular free tissue transfer in rats. We performed anatomical studies to collect data on muscle weight, dimension, vessel calibre and bone size in 20 flaps. This flap has a triangular shape with an average size of 38 x 39 x 32 mm and an average weight of 1.25 g; the scapular spine of 20 mm in average length can be harvested with the flap. The pedicle can be taken in continuity with the cervical trunk (average diameter of artery and vein were 0.5 mm and 0.6mm, respectively, with an average pedicle length of 12 mm). The flap was harvested and transferred to the groin area of the same rat and anastomosed to the superficial epigastric vessels. Fifteen transplantations were performed and the 7-day flap survival was 93.3%. The acromiotrapezius flap is believed to be a new and reliable osteomuscular model in the rat.

Animals↗

PubMed2000

Biliary tract reconstruction using an autologous vein graft in rats.

Numerous biologic and synthetic materials have been used with limited success as an interposed graft to repair segmental common bile duct (CBD) defects. The authors report here that an autologous vein graft can be successfully used to correct a CBD deficit contingent on accurate microsurgical technique immediate stenting and rapid graft vascularization. Thirty Sprague-Dawley rats underwent laparotomy and the experimental group (n=25) had a 3-mm segment of the CBD excised. The CBD defect was repaired using an interposed femoral vein graft aided by a plastic stent. The control group (n=5) had the CBD cut and repaired by means of primary anastomosis. The experimental group was subdivided into three sub-groups each examined at three different postoperative intervals: 1, 4 and 12 weeks. The results showed that inflammation was apparent in the venous wall following the first postoperative week. A progressive loss of the vascular endothelium and replacement with the columnar epithelium typical of the CBD was seen in the vein graft. Nineteen of the 25 experimental rats (76 percent) of the animals survived without complication from the surgery and there were no abnormalities in the liver biochemical tests of these animals. Any biliary tract obstruction that developed was attributed to dislocation of the stent leading to collapse of the vein graft (experimental group), or constriction of the anastomosis (control group). This study demonstrates that biliary tract reconstruction using an autologous vein graft can be successfully performed in a rat model of CBD repair. The application of this method to the clinical setting is also discussed.

Animals↗

PubMed2000

Free flap closure in complex congenital and acquired defects of the palate.

Extensive palatal defects cause substantial morbidity, including nasal regurgitation, poor oral hygiene, loose-fitting obturators, and difficulty with speech. Microvascular techniques allow the surgeon to repair these complex defects with a one-stage reconstruction, in contrast to possible multistage local or regional flap reconstruction. In this retrospective review, the authors present their 5-year experience with free flap coverage of extensive palatal defects. From 1993 to 1998, 6 patients underwent free flap coverage of large palatal defects. The etiology of the large palatal defects included trauma (N = 1), neoplasm (N = 4), and a recurrent congenital cleft palatal fistula (N = 1). Three patients underwent osteocutaneous radial forearm flaps and 1 patient underwent a fasciocutaneous radial forearm flap. The remaining 2 patients underwent rectus abdominis muscle flaps. The ipsilateral facial artery and vein were used as the recipient vessels in all patients. There were no intraoperative complications (surgical or anesthetic). Postoperatively, 2 patients had surgical evacuation of small flap hematomas. One patient underwent revision of the fasciocutaneous flap. All flaps survived. In our experience, the benefits of free flap reconstruction of complex palatal fistulas seem to outweigh the risks of the operation, with reliable long-term results.

Adolescent↗

PubMed2000

Economics of microsurgical cases and routine cases in a medical center.

This report describes the economic impact of microsurgical cases and routine plastic surgery cases in our medical center. The study is based on a financial analysis of the practices of two surgeons. Financial data of patient encounters (admission to the hospital or a surgical unit) identified with each surgeon were categorized into microsurgical and related cases and routine cases (including cosmetic procedures and general hand cases). Revenues, costs, and profits were tabulated. Data were analyzed for 2 fiscal years (1994-95 and 1995-96). Analysis of the first fiscal year showed that microsurgery encounters (n = 188) generated $4.4 million in revenue with a profit margin after direct costs of $2.5 million (57 percent) and a net profit, after indirect costs, of $1 million (23 percent). Routine encounters (n = 262) generated $1.7 million with a net loss of -$145,000 after direct and indirect costs. In the second fiscal year, microsurgery encounters (n = 230) had income of $4.7 million, a profit over direct costs of $2.5 million (53 percent), and a net profit after indirect costs of $0.9 million (19 percent). Routine cases (n = 202) in the same period earned $1.3 million with a net loss of -$107,000. This analysis formulates a comprehensive definition of microsurgical practice and shows that cases within this definition generated dramatically higher hospital incomes and profits compared with routine plastic surgical practice. In the circumstances of our medical center, development of this subspecialty is fiscally justifiable.

Academic Medical Centers↗

PubMed2000

Studies in flexor tendon wound healing: neutralizing antibody to TGF-beta1 increases postoperative range of motion.

The postoperative outcome of hand flexor tendon repair remains limited by tendon adhesions that prevent normal range of motion. Recent studies using in situ hybridization techniques have implicated transforming growth factor beta-1 (TGF-beta1) in both intrinsic and extrinsic mechanisms of repair. TGF-beta1 is a growth factor that plays multiple roles in wound healing and has also been implicated in the pathogenesis of excessive scar formation. The purpose of this study was to examine the effect of neutralizing antibody to TGF-beta1 in a rabbit zone II flexor tendon wound-healing model. Twenty-two adult New Zealand White rabbits underwent complete transection of the middle digit flexor digitorum profundus tendon in zone II. The tendons were immediately repaired and received intraoperative infiltration of one of the following substances: (1) control phosphate-buffered saline; (2) 50 microg neutralizing antibody to TGF-beta1; (3) 50 microg each of neutralizing antibody to TGF-beta1 and to TGF-beta2. Eight rabbits that had not been operated on underwent analysis for determination of normal flexion range of motion at their proximal and distal interphalangeal joints, using a 1.2-N axial load applied to the flexor digitorum profundus tendon. All rabbits that had been operated on were placed in casts for 8 weeks to allow maximal tendon adhesion and were then killed to determine their flexion range of motion. Statistical analysis was performed using the Student's unpaired t test. When a 1.2-N load was used on rabbit forepaws that had not been operated on, normal combined flexion range of motion at the proximal and distal interphalangeal joints was 93+/-6 degrees. Previous immobilization in casts did not reduce the range of motion in these forepaws (93+/-4 degrees). In the experimental groups, complete transection and repair of the flexor digitorum profundus tendon with infiltration of control phosphate-buffered saline solution resulted in significantly decreased range of motion between the proximal and distal phalanges [15+/-6 degrees (n = 8)]. However, in the tendon repairs infiltrated with neutralizing antibody to TGF-beta1, flexion range of motion increased to 32+/-9 degrees (n = 7; p = 0.002). Interestingly, a combination of neutralizing antibody to TGF-beta1 and that to TGF-beta2 did not improve postoperative range of motion [18+/-4 degrees (n = 7; p = 0.234)]. These data demonstrate that (1) the rabbit flexor tendon repair model is useful for quantifying tendon scar formation on the basis of degrees of flexion between proximal and distal phalanges; (2) intraoperative infiltration of neutralizing antibody to TGF-beta1 improves flexor tendon excursion; and (3) simultaneous infiltration of neutralizing antibody to TGF-beta2 nullifies this effect. Because TGF-beta1 is thought to contribute to the pathogenesis of excessive scar formation, the findings presented here suggest that intraoperative biochemical modulation of TGF-beta1 levels limits flexor tendon adhesion formation.

Animals↗

PubMed1999

Polypeptide resurfacing method improves fibroblast's adhesion to hyaluronan strands.

Hyaluronic acid (hyaluronan, HyA) is a matrix component that takes part in cell adhesion and growth in normal and repaired tissues. Since it is soluble in water, HyA has been of limited use in tissue engineering of artificial matrices. Recent studies demonstrate that polypeptides have the twin advantages of reducing solubility of HyA and improving cellular attachment via cell surface adhesion molecule receptors. This paper describes a new approach of using a polypeptide resurfacing method to enhance the attachment of cells to HyA strands. HyA strands were crosslinked by glutaraldehyde and then resurfaced with poly-D-lysine, poly-L-lysine, glycine, or glutamine. After inoculation with fibroblasts in vitro, modified HyA was evaluated with histological and immunohistochemical staining methods for cell adhesion and proliferation. Modified HyA with fibroblast cells also were implanted in vivo. The results show that (1) both polylysines enhanced fibroblast adhesion to crosslinked HyA strands; (2) HyA strands were able to be crosslinked well by 3 days of treatment in glutaraldehyde, and as a biomaterial they could resist biodegradation; (3) modified HyA has good biocompatibility, both in vitro and in vivo. The results demonstrate that HyA material resurfaced by polypeptides has positive advantages for cellular adhesion. Resurfaced HyA has much potential as an improved biomaterial for clinical usage.

Animals↗

PubMed1999

Development of a mouse limb transplantation model.

A tremendous amount of research has been dedicated to laying the groundwork that will eventually lead to successful limb transplantation in humans. Limb transplantation in animal models has also been widely used for evaluating composite tissue allografts and various immunosuppressive regimens. Currently, there is no mouse model of limb transplantation. Such a model is attractive because it would allow investigators to apply the well-defined genetic characteristics of the mouse to the challenging field of limb transplantation. In this study, 12 mice underwent orthotopic hind limb transplantations using end-to-end anastomoses of the femoral vessels. The success rate of this surgical procedure was 83%, with 10 of the 12 limbs surviving. Experimental devices, operative procedures, and the major elements of success are discussed.

Anastomosis, Surgical↗

PubMed1999

Calf augmentation using free TRAM flap.

Augmentation of the calf for correction of contour deformities has been most frequently performed utilizing silicone implants. Results of such implants have often been unsatisfactory. We report the case of a 27-year-old woman who chose the use of a transverse rectus abdominis myocutaneous (TRAM) free flap for correction of a left calf contour deformity from childhood polio. This is the first report of calf augmentation with the use of a TRAM free flap and excellent results were obtained.

Adult↗

PubMed1999

Compartment syndrome of the forearm as the initial symptom of systemic Vibrio vulnificus infection.

Sepsis, cellulitis, and necrotizing fasciitis rarely have been described as causes of compartment syndrome. We report a case in which forearm compartment syndrome presented as the initial symptom of systemic infection. Vibrio vulnificus, the etiologic pathogen of the compartment syndrome, was isolated from wound and blood cultures. The patient was treated with systemic antibiotic treatment and multiple forearm fasciotomies. The infectious process progressed rapidly, however and due to underlying liver insufficiency, the patient died of hepatorenal syndrome. This case illustrates the nature of V. vulnificus infections, which are characterized by shellfish transmission, predilection for soft tissue seeding, and a fulminant course in the compromised host.

Animals↗

PubMed1999

Z-plasty closure of the donor defect of the radial forearm free flap.

The radial forearm is a popular free flap site for reconstruction of head and neck defects, because of its abundant, pliable, skin component and an available, extended, vascular pedicle. In addition, vascularized composite flaps, including a segment of radius, can be designed for skeletal stabilization. The donor-site defect can involve various complications, including loss of skin graft, unsatisfactory appearance, numbness, and radial fracture. Recent advances in reducing donor-site defect problems have included the use of rotation skin flaps, local muscle rotation, and soft-tissue expansion; however, each of these has its own limitations. Two cases are presented in which radial forearm donor site defects, measuring less than 4 cm x6 cm, were primarily closed successfully with z-plasties based on the longitudinal skin incision. Each patient has regained preoperative mobility, and prompt primary healing was achieved without complications.

Adult↗

PubMed1999

Functional assessment of the shoulder following latissimus dorsi muscle donation in the handicapped.

The latissimus dorsi muscle, one of the largest muscles in the human body, has gained widespread popularity in microsurgical reconstruction. Because the latissimus serves to adduct and medially rotate the upper extremity, caution in its use has been advocated in handicapped and non-ambulatory patients, although a paucity of information exists in the literature. The purpose of this reported project was to determine whether the loss of the latissimus dorsi could be documented objectively or subjectively, either in the preoperative condition or post-harvesting in the handicapped patients. Two paraplegic patients were studied. Results indicate a lack of objective functional deficit; this includes both the nerve-blocked state and the postoperative condition. In addition, both patients failed to demonstrate the need to change any activities of daily living. This evidence suggests that, although careful decisions must be made on a case-by-case basis, the use of the latissimus dorsi muscle is not necessarily contraindicated in this group of patients.

Abdominal Neoplasms↗

PubMed1999

Shortening of rat teeth prevents autocannibalization of surgical flaps.

Self-biting in laboratory rats is an irritating problem that can impede progress and affect the credibility of experimental interventions. Autocannibalization frequently complicates the epigastric skin flap model that is often used to evaluate flaps. In one of the authors' studies, the autocannibalization rate of 55.6 percent in nine rats with unprotected skin flaps of the entire abdominal wall necessitated the application of previously reported plastic collars and protective vests to hinder self-biting. Because the use of these devices resulted in distress symptoms in nine of 11 rats with collars and flap congestion in five of five rats with vests, rat incisor teeth shortening was introduced as a stress-free method to prevent chewing. Careful teeth cutting obviated autocannibalization in 19 of 20 rats (p<0.01) during a 5-day follow-up. Rat incisor teeth shortening performed every 3 or 4 days is a simple, inexpensive, and reliable method to prevent autocannibalization in the rat, while maintaining the well-being of the animal.

Animals↗

PubMed1999

Quadriceps femoris muscle flap: largest muscle flap model in the rat.

The purpose of this paper is to present a new muscle flap in the rat: the quadriceps femoris muscle flap based on a pedicle consisting of the femoral vessels. In order to establish the anatomic details of this model, seven rats were explored bilaterally, and the regional anatomy of the thigh was examined. The technical aspect of the model was established by the unilateral harvesting of 18 quadriceps femoris muscles. Findings were that this muscle is primarily supplied by a muscular branch originating at the superficial circumflex iliac artery. The average muscle weight was 6 g and the average pedicle length with femoral vessels was 6 mm. Eight of the harvested flaps were transplanted to the contralateral thigh, and the pedicle was anastomosed to the femoral vessels. The other ten flaps were resutured back to their beds. At 72 hr postoperatively, all flaps were viable with the exception of one of the transplanted flaps which was found to be necrotic. The quadriceps femoris muscle flap is technically both a reliable and simple model. With an average weight of 6 g, this flap is by far the largest described in the rat, and offers a convenient model for testing flap-related techniques and outcomes.

Animals↗

PubMed1999

Effect of hyperbaric oxygen on microvascular anastomosis healing and patency in the rat.

Recent evidence has shown that changes in blood viscosity and marked increases in both platelet count and fibrinogen concentration occur after exposure to hyperbaric oxygen (HBO). The purpose of the present study was to address whether repeated HBO therapy would increase either hematocrit or platelet count, and to determine if these changes would influence the patency of the microvascular anastomosis, as well as anastomotic healing. Eighty femoral arteries from 40 rats were divided into four groups (n = 10), and arterial anastomoses were performed on normal arteries in the first two groups, and on crushed arteries in the second two groups. One of the normal artery groups and one of the crushed artery groups received repeated HBO treatments for 5 days. Anastomotic patency rates, platelet count, hematocrit, and breaking strength were recorded. Among the results of this study were that: (1) there was no difference in patency rate following HBO treatment in both the normal and crushed artery groups; (2) platelet count was significantly higher following HBO treatment in the groups with the undamaged arteries; (3) breaking strength was significantly increased following HBO treatment in the groups with the crushed arteries. The authors concluded that HBO therapy may be useful in improving the healing of microvascular anastomoses in vessels that have undergone crush injury. Although HBO treatment results in an increased platelet count, this does not influence anastomotic patency.

Anastomosis, Surgical↗

PubMed1999

Prolonged perivascular use of verapamil or lidocaine decreases skin flap necrosis.

During this experiment the authors investigated whether prolonged local use of verapamil or lidocaine prevents vasoconstriction and establishes better blood supply to the rat epigastric skin flap, hence reducing the necrosis that occurs otherwise. Abdominal wall skin flaps of 45 Sprague-Dawley rats, based on a single pedicle of the femoral vessels, were elevated. A subcutaneous pocket for the microport valve was created, and the adjacent catheter tip was sewn next to the femoral vessels. In the control and the two treatment groups, 0.5 ml saline or vasodilator solution respectively was injected through the microport every 12 hours for 5 days. On postoperative day 5 there was no statistical difference between the flap surfaces in all groups. The area of flap necrosis was significantly lower in the verapamil- (p = 0.001) and the lidocaine-treated (p = 0.012) groups vs. the control group as determined by analysis of variance with Bonferroni's post hoc test. In conclusion, topical application of verapamil and lidocaine solutions for 5 postoperative days decreased flap marginal necrosis significantly. Prolonged injection of vasodilators in the vicinity of the vascular pedicle prevents vasospasm and improves blood supply to the flap.

Administration, Topical↗

PubMed1999

Saphenous neurocutaneous island flap model in the rat: evaluation of vascular supply.

Neurocutaneous flaps are utilized routinely in reconstructive surgery and even more so during the past decade. In this study, the vascular supply of the neurocutaneous flap in the rat model is presented and evaluated. Thirty-six flaps (3.5x3 cm2) were dissected on the medial aspect of the leg based on a pedicle of the saphenous nerve, saphenous artery, great saphenous vein, and the surrounding fascial tissues. Animals in the experiment were divided into five groups with different circulatory patterns of pedicle dissections. In group I (N = 12), the pedicle artery, vein, nerve, and fascia were preserved. In group II (neurocutaneous flap model, N = 24), the saphenous artery was transected and the vein, nerve, and fascia were preserved. In group III (intraneural vascular plexus circulation pattern, N = 12), the saphenous artery and the fascia were transected. In group IV (extraneural vascular plexus circulation pattern, N = 12), the saphenous artery and nerve were transected. In group V (N = 12), the entire pedicle was transected completely. Flap survival was evaluated grossly on postoperative day 7. All flaps survived in group I, but in group II 19 of 24 flaps survived completely, 3 of 24 had partial necrosis, and 2 of 24 were completely necrotic. Complete necrosis was observed in all group III flaps. In group IV, 6 of 12 flaps survived completely, 3 of 12 flaps survived partially, and 3 of 12 flaps were necrotic (p<0.05 vs. group I). Only one flap with partial necrosis survived in group V. In group II, the average survival area was not significantly different from group I (p>0.05). In conclusion, the saphenous neurocutaneous flap in the rat is a reliable microsurgical model. The saphenous neurocutaneous flap is commonly supplied by both the intraneural and extraneural vascular plexus, and although the latter is more important, neither provides sufficient vascular supply on its own.

Animals↗

PubMed1999

The role of the plastic surgeon in the management of surgical infection.

At our Medical Center, our reconstructive service has actively sought referrals of acute and chronic infections by declaring an interest in undertaking the integrated management and reconstruction of these cases. The practices of the two senior surgeons were reviewed for three academic years (1992 to 1995). Cases of surgical infection were analyzed as to site, ablative procedures, and reconstructive procedures. In total, 139 patients with 147 infections were identified. Sites of infection included head and neck (9.5 percent), trunk and pelvis (39.5 percent), upper extremity (22 percent), and lower extremity (29 percent). One-hundred thirty-one ablative procedures were done on this group, as were 126 reconstructive procedures, including 17 fasciocutaneous flaps, 26 pedicled muscle flaps, and 28 microsurgical flaps. With a mean follow-up of 14 months, 92 percent of these patients had resolution of infection. The 8 percent failure group included recurrences, amputation, and death. This series demonstrates that a plastic surgery service can attract a diverse population of surgical infections and manage them successfully with ablation and a wide variety of reconstructive procedures. The coordination of ablation and reconstruction may be optimally performed by the plastic surgeon.

Adult↗