Vibrational Spectroscopy as a Promising Toolbox for Analyzing Functionalized Ceramic Membranes.

Ceramic materials find use in many fields including the life sciences and environmental engineering. For example, ceramic membranes have shown to be promising filters for water treatment and virus retention. The analysis of such materials, however, remains challenging. In the present study, the potential of three vibrational spectroscopic methods for characterizing functionalized ceramic membranes for water treatment is evaluated. For this purpose, Raman scattering, infrared (IR) absorption, and solvent infrared spectroscopy (SIRS) were employed. The data were analyzed with respect to spectral changes as well as using principal component analysis (PCA). The Raman spectra allow an unambiguous discrimination of the sample types. The IR spectra do not change systematically with functionalization state of the material. Solvent infrared spectroscopy allows a systematic distinction and enables studying the molecular interactions between the membrane surface and the solvent.

Supercritical CO2 impregnation of PLA/PCL films with natural substances for bacterial growth control in food packaging.

Biodegradable polymers with antibacterial properties are highly desirable materials for active food packaging applications. Thymol, a dietary monoterpene phenol with a strong antibacterial activity is abundant in plants belonging to the genus Thymus. This study presents two approaches for supercritical CO2 impregnation of poly(lactic acid)(PLA)/poly(ε-caprolactone)(PCL) blended films to induce antibacterial properties of the material: (i) a batch impregnation process for loading pure thymol, and (ii) an integrated supercritical extraction-impregnation process for isolation of thyme extract and its incorporation into the films, operated in both batch or semi-continuous modes with supercritical solution circulation. The PCL content in films, impregnation time and CO2 flow regime were varied to maximize loading of the films with thymol or thyme extract with preserving films' structure and thermal stability. Representative film samples impregnated with thymol and thyme extract were tested against Gram (-) (Escherichia coli) and Gram(+) (Bacillus subtilis) model strains, by measuring their metabolic activity and re-cultivation after exposure to the films. The film containing thymol (35.8 wt%) showed a strong antibacterial activity leading to a total reduction of bacterial cell viability. Proposed processes enable fast, controlled and organic solvent-free fabrication of the PLA/PCL films containing natural antibacterial substances at moderately low temperature, with a compact structure and a good thermal stability, for potential use as active food packaging materials.

Flow rate dependent continuous hydrolysis of protein isolates.

Food protein hydrolysates are often produced in unspecific industrial batch processes. The hydrolysates composition underlies process-related fluctuations and therefore the obtained peptide fingerprint and bioactive properties may vary. To overcome this obstacle and enable the production of specific hydrolysates with selected peptides, a ceramic capillary system was developed and characterized for the continuous production of a consistent peptide composition. Therefore, the protease Alcalase was immobilized on the surface of aminosilane modified yttria stabilized zirconia capillaries with a pore size of 1.5 µm. The loading capacity was 0.3 µg enzyme per mg of capillary with a residual enzyme activity of 43%. The enzyme specific peptide fingerprint produced with this proteolytic capillary reactor system correlated with the degree of hydrolysis, which can be controlled over the residence time by adjusting the flow rate. Common food proteins like casein, sunflower and lupin protein isolates were tested for continuous hydrolysis in the developed reactor system. The peptide formation was investigated by high-performance liquid chromatography. Various trends were found for the occurrence of specific peptides. Some are just intermediately occurring, while others cumulate by time. Thus, the developed continuous reactor system enables the production of specific peptides with desired bioactive properties.

Straightforward Processing Route for the Fabrication of Robust Hierarchical Zeolite Structures.

Strong hierarchical porous zeolite structures are prepared by a sol-gel method using freeze gelation. Instead of conventional binders in powder form, such as bentonite or kaolin, it has been proven that using a freeze gelation method based on a colloidal silica sol is a more straightforward and easier-to-use-approach in fabricating highly mechanically stable zeolite monoliths. The resulting zeolite slurries possess superior rheological properties (not being pseudoplastic) and show low viscosities. This low viscosity of the slurry enables an increase in the solid content without compromising the extraordinary good flow behavior for casting applications. Additionally, in comparison to conventional powdery binders, zeolite samples prepared by using a colloidal silica sol exhibit a significantly higher mechanical strength. This mechanical strength can be further improved by either increasing the zeolite content or increasing the silica to zeolite ratio. Increasing the zeolite content leads to an increased volumetric adsorption capacity for CO2 as the test gas, resulting from the increased amount of zeolite particles per unit volume. In addition, a higher solid content of the zeolite monoliths leads to higher compression strengths, while showing the same elastic deformation and brittle failure characteristics. In turn, increasing the silica to zeolite ratio does not affect the volumetric adsorption capacity for CO2. Nevertheless, higher silica contents lead to a significant increase in the elastic deformation and absorbed work until failure. Therefore, the proposed processing route based on freeze gelation presents an easy and unique tool to tune the mechanical and gas adsorptive properties of hierarchically structured zeolite monoliths, according to the application requirements.

Applying Alkyl-Chain Surface Functionalizations in Mesoporous Inorganic Structures: Their Impact on Gas Flow and Selectivity Depending on Temperature.

Porous inorganic capillary membranes are prepared to serve as model structures for the experimental investigation of the gas transport in functionalized mesopores. The porous structures possess a mean pore diameter of 23 nm which is slightly reduced to 20 nm after immobilizing C16-alkyl chains on the surface. Gas permeation measurements are performed at temperatures ranging from 0 to 80 °C using Ar, N2, and CO2. Nonfunctionalized structures feature a gas transport according to Knudsen diffusion with regard to gas flow and selectivity. After C16-functionalization, the gas flow is reduced by a factor of 10, and the ideal selectivities deviate from the Knudsen theory. CO2 adsorption measurements show a decrease in total amount of adsorbed gas and isosteric heat of adsorption. It is hypothesized that the immobilized C16-chains sterically influence the gas transport behavior without a contribution from adsorption effects. The reduced gas flow derives from an additional surface resistance caused by the C16-chains spacially limiting the adsorption and desorption directions for gas molecules propagating through the structure, resulting in longer diffusion paths. In agreement, the gas flow is found to correlate with the molecular diameter of the gas species (CO2 < Ar < N2) increasing the resistance for larger molecules. This affects the ideal selectivities with the relation [Formula: see text]. The influence on selectivity increases with increasing temperature which leads to the conclusion that the temperature induced movement of the C16-chains is responsible for the stronger interaction between gas molecules and surface functional groups.

Amino-Functionalized Ceramic Capillary Membranes for Controlled Virus Retention.

A straightforward chemical functionalization strategy using aminosilanes for high-flux yttria-stabilized zirconia capillary membranes is presented (macroporous, d50 = 144 nm, open porosity =49%, membrane flux ∼150 L/(m(2)hbar)). Three different aminosilanes with one, two or three amino groups per silane molecule, namely 3-aminopropyltriethoxysilane (APTES), N-(2-aminoethyl)-3-aminopropyltriethoxysilane (AE-APTES) and N-(3-trimethoxysilylpropyl)diethylenetriamine (TPDA), are used to generate the amino-functionalized membranes. With a higher number of amino groups per silane molecule increased loading capacities between 0.44 and 1.01 accessible amino groups/nm(2) membrane are achieved. Streaming potential measurements confirm that the zeta-potential of the membrane surface is converted from negative (non-functionalized) to positive (amino-functionalized). By operation in dead-end filtration mode using the model virus MS2 (diameter = 25 nm, IEP = 3.9) the virus retention capacity of the amino-functionalized membranes is significantly increased and log reduction values (LRVs) of up to 9.6 ± 0.3 (TPDA) are obtained whereas a LRV < 0.3 is provided by the non-functionalized membranes. Long-term dead-end filtration experiments for 1 week reveal a high stability of immobilized aminosilanes (TPDA), being robust against leaching. By iterative backflushing with desorption buffer MS2-loaded membranes are successfully regenerated being reusable for a new filtration cycle. The presented functionalization platform is highly promising for controlled virus retention.

Hierarchical Porous Zeolite Structures for Pressure Swing Adsorption Applications.

Porous adsorbents with hierarchical structured macropores ranging from 1 to 100 µm are prepared using a combination of freeze casting and additional sacrificial templating of polyurethane foams, with a zeolite 13X powder serving as adsorbent. The pore system of the prepared monoliths features micropores assigned to the zeolite 13X particle framework, interparticular pores of ∼1-2 µm, lamellar pores derived from freeze casting of ∼10 µm, and an interconnected pore network obtained from the sacrificial templates ranging from around 100 to 200 µm with a total porosity of 71%. Gas permeation measurements show an increase in intrinsic permeability by a factor of 14 for monoliths prepared with an additional sacrificial templated foam compared to monoliths solely providing freeze casting pores. Cyclic CO2 adsorption and desorption tests where pressure swings between 8 and 140 kPa reveal constant working capacities over multiple cycles. Furthermore, the monoliths feature a high volumetric working capacity of ∼1.34 mmol/cm(3) which is competitive to packed beds made of commercially available zeolite 13X beads (∼1.28 mmol/cm(3)). Combined with the faster CO2 uptake showing an adsorption of 50% within 5-8 s (beads ∼10 s), the monoliths show great potential for pressure swing adsorption applications, where high volumetric working capacities, fast uptakes, and low pressure drops are needed for a high system performance.

Silver nanoparticle-doped zirconia capillaries for enhanced bacterial filtration.

Membrane clogging and biofilm formation are the most serious problems during water filtration. Silver nanoparticle (Agnano) coatings on filtration membranes can prevent bacterial adhesion and the initiation of biofilm formation. In this study, Agnano are immobilized via direct reduction on porous zirconia capillary membranes to generate a nanocomposite material combining the advantages of ceramics being chemically, thermally and mechanically stable with nanosilver, an efficient broadband bactericide for water decontamination. The filtration of bacterial suspensions of the fecal contaminant Escherichia coli reveals highly efficient bacterial retention capacities of the capillaries of 8 log reduction values, fulfilling the requirements on safe drinking water according to the U.S. Environmental Protection Agency. Maximum bacterial loading capacities of the capillary membranes are determined to be 3×10(9)bacterialcells/750mm(2) capillary surface until back flushing is recommendable. The immobilized Agnano remain accessible and exhibit strong bactericidal properties by killing retained bacteria up to maximum bacterial loads of 6×10(8)bacterialcells/750mm(2) capillary surface and the regenerated membranes regain filtration efficiencies of 95-100%. Silver release is moderate as only 0.8% of the initial silver loading is leached during a three-day filtration experiment leading to average silver contaminant levels of 100µg/L.

Highly efficient enzyme-functionalized porous zirconia microtubes for bacteria filtration.

In contrast to polymer membranes, ceramic membranes offer considerable advantages for safe drinking water provision due to their excellent chemical, thermal, and mechanical endurance. In this study, porous ceramic microtubes made of yttria stabilized zirconia (YSZ) are presented, which are conditioned for bacteria filtration by immobilizing lysozyme as an antibacterial enzyme. In accordance with determined membrane pore sizes of the nonfunctionalized microtube of ≤200 nm, log reduction values (LRV) of nearly 3 (i.e., bacterial retention of 99.9%) were obtained for bacterial retention studies using gram-positive model bacterium Micrococcus luteus. Immobilization studies of lysozyme on the membrane surface reveal an up to six times higher lysozyme loading for the covalent immobilization route as compared to unspecific immobilization. Antibacterial activity of lysozyme-functionalized microtubes was assessed by qualitative agar plate test using Micrococcus luteus as substrate showing that both the unspecific and the covalent lysozyme immobilization enhance the microtubes' antibacterial properties. Quantification of the enzyme activity at flow conditions by photometric assays reveals that the enzyme activities of lysozyme-functionalized microtubes depend strongly on applied flow rates. Intracapillary feeding of bacteria solution and higher flow rates lead to reduced enzyme activities. In consideration of different applied flow rates in the range of 0.2-0.5 mL/min, the total lysozyme activity increases by a factor of 2 for the covalent immobilization route as compared to the unspecific binding. Lysozyme leaching experiments at flow conditions for 1 h show a significant higher amount of washed-out lysozyme (factor 1.7-3.4) for the unspecific immobilization route when compared to the covalent route where the initial level of antibacterial effectiveness could be achieved by reimmobilization with lysozyme. The presented platform is highly promising for sustainable bacteria filtration.

A semi-quantitative dipstick assay for microcystin.

An immunochromatographic lateral flow dipstick assay for the fast detection of microcystin-LR was developed. Colloid gold particles with diameters of 40 nm were used as red-colored antibody labels for the visual detection of the antigen. The new dipstick sensor is capable of detecting down to 5 microg x l(-1) (ppb; total inversion of the color signal) or 1 ppb (observation of color grading) of microcystin-LR. The course of the labeling reaction was observed via spectrometric wave shifts caused by the change of particle size during the binding of antibodies. Different stabilizing reagents showed that especially bovine serum albumin (BSA) and casein increase the assays sensitivity and the conjugate stability. Performance of the dipsticks was quantified by pattern processing of capture zone CCD images. Storage stability of dipsticks and conjugate suspensions over 115 days under different conditions were monitored. The ready-to-use dipsticks were successfully tested with microcystin-LR-spiked samples of outdoor drinking- and salt water and applied to the tissue of microcystin-fed mussels.

Development of a novel membrane aerated hollow-fiber microbioreactor.

A new challenge in biotechnological processes is the development of flexible bioprocessing platforms, allowing strain selection, facilitating scale-up and integrating separation steps. Miniaturization of such a cultivation system allows parallel use and the saving of resources but makes the supply of oxygen to the cells difficult. In this work we present a membrane aerated hollow-fiber microbioreactor (HFMBR) which consists of an acrylic glass module equipped with two different types of membrane fibers. Fibers of polyethersulfone and polyvinyldifluoride were used for substrate and oxygen supply, respectively. Cultivation of E. coli as model organism and production of His-tagged GFP were carried out in the extracapillary space of the membrane aerated HFMBR and compared with cultivations in shaking flask which are commonly used for screening experiments. The measurement of the oxygen transfer capacity and the online monitoring of the dissolved oxygen during the cultivation were performed using a fiber optic oxygen sensor. Online measurement of the optical density was also integrated to the bioreactor. Due to efficient oxygen transfer, a better cell growth than in the shaking flask experiments was achieved, while no negative influence on the GFP productivity was observed in the membrane aerated bioreactor. Thus the feasibility of a future integrated downstreaming could also be demonstrated.

Microvascular breast reconstruction in the diabetic patient.

BACKGROUND: The free transverse rectus abdominis musculocutaneous (TRAM) flap is frequently advocated for autogenous breast reconstruction following mastectomy. The success rate and complications associated with free TRAM flap breast reconstruction are well documented. Risk factors such as cigarette smoking and obesity have been studied. Because of abnormalities in endothelial and red cell function, platelet function, altered blood viscosity, and abnormal intimal repair, diabetes mellitus is generally considered to be a risk factor for free TRAM flap breast reconstruction. The success rate of microvascular TRAM flap breast reconstruction in patients with diabetes mellitus has not been clearly defined. METHODS: A retrospective review of 893 free TRAM flaps used for breast reconstruction in 763 patients at a single institution was performed. All flaps were performed at M. D. Anderson Cancer Center after January 1, 1985, and before December 31, 1997. Patients were classified as insulin-dependent (type 1) diabetic, non-insulin-dependent (type 2) diabetic, and nondiabetic. Flap and donor-site complications were compared among the three groups. Multivariate statistical analysis was used to examine demographic characteristics, body mass index, comorbid conditions, preoperative radiation therapy, immediate versus delayed reconstruction, and smoking history in patients with type 1 diabetes mellitus, type 2 diabetes mellitus, and nondiabetic patients. RESULTS: The incidence of flap complications did not differ significantly between type 1 diabetics, type 2 diabetics, and nondiabetic patients. The incidence of donor-site complications did not differ significantly between type 1 diabetics, type 2 diabetics, and nondiabetic patients. CONCLUSION: The present data indicate that type 1 diabetes mellitus and type 2 diabetes mellitus are not relative or absolute contraindications to microvascular TRAM flap breast reconstruction.

Cavernous nerve reconstruction to preserve erectile function following non-nerve-sparing radical retropubic prostatectomy: a prospective study.

Erectile dysfunction following radical prostatectomy for treatment of clinically localized prostate cancer remains a problem that deters many men from seeking surgical treatment. Sparing the cavernous nerves has been popularized as a method of preserving potency, but men with locally advanced disease may be at increased risk for positive margins with this technique. In this study, sural nerve grafting of the cavernous nerve bundles, to preserve postoperative potency while potentially maximizing cancer control, was examined. Thirty men were enrolled in this prospective phase I study and underwent non-nerve-sparing radical prostatectomy performed by one of two protocol surgeons. Preoperative erectile function was assessed both objectively, using a RigiScan (Timm Medical Technologies, Inc., Eden Prairie, Minn.), and subjectively. The cavernous nerves were identified and resected during the operation with the use of an intraoperative mapping device (CaverMap; Alliant Medical Technologies, Norwood, Mass.). Bilateral autologous sural nerve grafting to the cavernous nerve stumps was performed by one of two protocol plastic surgeons. Postoperative erectile dysfunction therapy, using intracorporeal injection, a vacuum pump, and/or oral sildenafil therapy, was instituted 6 weeks after the operation. Spontaneous erectile activity was subjectively and objectively measured every 3 months after the operation. Follow-up periods ranged from 13 to 33 months (mean, 23 months). Overall, 18 of 30 patients (60 percent) demonstrated both objective and subjective evidence of spontaneous erectile activity. Of those 18 men, 13 (72 percent) were able to have intercourse (seven unassisted and six with the aid of sildenafil). No disease or biochemical recurrences have been noted in this group of patients with locally advanced disease. In conclusion, autologous sural nerve grafting after non-nerve-sparing radical prostatectomy is an effective means of preserving spontaneous erectile activity after the operation while maximizing cancer control potential.

Breast cancer recurrence after immediate reconstruction: patterns and significance.

Local recurrence of cancer after mastectomy and immediate breast reconstruction is generally regarded as a poor prognostic indicator. This study was conducted to identify specific patterns of local recurrence following reconstruction and to determine their biological significance. The records of all patients who had undergone immediate breast reconstruction at The University of Texas M. D. Anderson Cancer Center between June 1, 1988, and December 31, 1998, were reviewed. The records of patients who had local tumor recurrence were then carefully analyzed. During this 10-year period, a local recurrence of cancer was found to have developed in 39 of 1694 patients (2.3 percent). Most recurrences were in the skin or subcutaneous tissue (n = 28; 72 percent), and the remainder were in the "chest wall" (n = 11; 28 percent), as defined by skeletal or muscular involvement. Transverse rectus abdominis myocutaneous flaps were used most often in both groups, but latissimus dorsi myocutaneous flaps and implant techniques were also used in some patients. Patients with subcutaneous tissue recurrence had an overall survival rate of 61 percent at follow-up of 80.8 months, compared with patients with chest wall recurrence, whose survival rate was 45 percent at similar follow-up. Metastases were less likely to develop in patients with subcutaneous tissue recurrence than in those with chest wall recurrence (57 percent versus 91 percent; p = 0.044); the former group also had a greater chance of remaining disease-free after treatment of the recurrence (39 percent versus 9 percent), respectively. Metastasis-free survival was higher in patients with subcutaneous tissue recurrence than with chest wall recurrence (2-year and 5-year survival: 52 and 42 percent versus 24 and 24 percent; p = 0.04). In both groups, the time to detection of the recurrence was similar (subcutaneous tissue recurrence, 27.1 months, versus chest wall recurrence, 29.5 months). Distant disease did not develop in one patient only in the chest wall recurrence group; this patient remained disease-free at 70 months. From these results, it was concluded that (1) not all local recurrences are the same: patients with subcutaneous tissue recurrence have better survival rates, a decreased incidence of metastases, and a greater chance of remaining disease-free than do those with chest wall recurrence; (2) immediate breast reconstruction (although potentially, it can conceal chest wall recurrence) does not seem to delay the detection of chest wall recurrence; and (3) even if a chest wall recurrence develops, it is highly associated with metastatic disease, and the survival rate is not likely to have been influenced by earlier detection. These data support the continued use of immediate breast reconstruction without fear of concealing a recurrence or influencing the oncologic outcome.

Implications of axillary sentinel lymph node biopsy in immediate autologous breast reconstruction.

For patients with invasive breast cancer, if the results of an axillary sentinel node biopsy are determined to be positive after permanent pathologic examination, the current recommendation is to perform a complete axillary node dissection. Subsequent axillary surgery may compromise the blood supply to an immediate autologous breast reconstruction. The purpose of this study was to determine which clinicopathologic factors in clinically node-negative breast cancer patients may be associated with an increased risk of positive axillary nodes. Identification of these factors will allow surgeons to modify their approach to immediate autologous breast reconstruction in these high-risk patients. The relationship between presenting clinicopathologic characteristics and the incidence of axillary metastases was analyzed by chi-square test and multivariate analysis in 167 patients with invasive breast cancer and a clinically negative axilla who underwent modified radical mastectomy with an immediate free transverse rectus abdominis musculocutaneous (TRAM) flap reconstruction. Axillary nodal metastases were found in 35 percent of clinically node-negative breast cancer patients. Multivariate analysis showed that patient age of 50 years or younger (p = 0.019), T2 tumor stage or greater (p = 0.031), and presence of lymphovascular invasion on the initial biopsy specimen (p < 0.001) were independent predictors of axillary metastases in clinically node-negative patients. Based on these results, the authors propose an algorithm for decision making in clinically node-negative breast cancer patients who desire autologous breast reconstruction and sentinel lymph node biopsy. Options for immediate autologous breast reconstruction in patients undergoing mastectomy and axillary sentinel lymph node biopsy that may minimize the risk of vascular damage on reoperation include the use of the internal mammary artery and vein as recipient vessels for a free TRAM flap or a pedicled TRAM flap. If an axillary-based blood supply is used, the authors are considering the use of cadaveric dermis to isolate the pedicle of the flap away from the remaining axillary contents. New developments in breast cancer diagnosis and treatment necessitate a team approach, with increased communication between the breast surgeon and the plastic surgeon in planning surgery for these patients.

Drains and seromas in TRAM flap breast reconstruction.

Surgeons who perform transverse rectus abdominis musculocutaneous (TRAM) flaps have differing opinions about how many drains are required in the breast and abdomen to prevent seroma. The authors therefore decided to review their experience to determine whether the number of drains influenced the incidence of seroma. All patients who underwent breast reconstruction using TRAM or deep inferior epigastric perforator flaps at The University of Texas M. D. Anderson Cancer Center from January 1, 1995 to June 20, 2000 and whose charts could be retrieved were included in the study. The number of drains used was correlated with the presence or absence of seroma and wound infection in both the abdomen and the breast. Significance was analyzed using the Chi-squared and Fisher's exact tests. There were 608 patients and 768 reconstructive procedures in this series (160 reconstructions were bilateral). Of patients who had only one drain in the abdomen, seroma developed in 9 patients (7.1%), whereas of those having two drains in the abdomen, seroma developed in only 10 patients (2.1%) (p = 0.006). Also, of patients who had only one drain in the breast, seroma developed in the breast in 47 patients (9.1%), and in those with two drains, seroma developed in only 11 patients (4.3%) (p = 0.02). There were no significant differences in the infection rate in either the breast or the abdomen, although the trends favored a lower infection risk when two drains were used. The authors found that using two drains in both the abdomen and the breast can reduce the risk for seroma without increasing the risk for infection. This study supports the use of two drains in both the breast (one each beneath the TRAM flap and in the axilla) and abdomen (beneath the abdominoplasty flap) for patients undergoing breast reconstruction using the TRAM flap.

Limb salvage for soft-tissue malignancies of the foot: an evaluation of free-tissue transfer.

Free flaps may safely allow meaningful ambulation, durable limb preservation, and better quality of life in patients undergoing resections of soft-tissue cancers of the foot. To prove this, the records of a series of patients at The University of Texas M. D. Anderson Cancer Center (n = 67) who underwent limb salvage following tumor-related resection (n = 71 procedures) from 1989 to 1999 were retrospectively reviewed. Eighteen patients who were not candidates for local flaps or skin grafts received a total of 20 free flaps to preserve their limbs. Most defects (mean size, 78 cm2; range, 20 to 150 cm2) were on a weight-bearing surface of the foot (nine on a weight-bearing heel, three on a plantar foot); the remainder were on a non-weight-bearing surface (six on dorsum, two on a non-weight-bearing heel). Melanoma was diagnosed in nine cases (50 percent); soft-tissue sarcoma, in seven (39 percent); and squamous cell carcinoma, in two (11 percent). Fasciocutaneous and skin-grafted muscle flaps were used on both weight-bearing and non-weight-bearing surfaces. Free-tissue transfer was successful in 17 of 20 cases (85 percent); the three flap losses occurred in two patients. Minor complications (i.e., small hematoma, partial skin graft loss, and delayed wound healing) occurred in five patients. In all cases of successful free-tissue transfer, patients began partial weight bearing at a mean of 7.4 weeks (range, 2 to 12 weeks), and all ultimately achieved full weight bearing. Sixty-seven percent still required special footwear. In one patient, an ulceration on the weight-bearing portion of the flap resolved after a footwear adjustment. Only one patient was lost to follow-up (mean, 23 months). In the 17 remaining patients, limb salvage succeeded in 15 (88 percent). Of these, nine (60 percent) were alive without evidence of disease, three (20 percent) were alive with disease, and three (20 percent) had died of disease. Local recurrence developed in two patients but was successfully treated by excision and closure. No late amputations were required for local control. Thus, it seems that free flaps help facilitate limb salvage and that they may preserve meaningful limb function in patients who undergo resection of soft-tissue malignancies of the foot.