Bowel seromuscular flaps used to repair pelvic defects in patients undergoing reoperative surgery.

BACKGROUND: Pedicled seromuscular bowel flaps may serve as an alternative for pelvic floor reconstruction when conventional omental and muscular flaps are not an option in patients undergoing reoperative abdominopelvic surgery. The aim of this study was to evaluate a unique series of bowel seromuscular flaps used to obliterate intrapelvic defects. METHODS: We conducted a retrospective study on all patients in a single tertiary care institutional database who had undergone pelvic reconstruction with a seromuscular bowel flap from January 2006 to December 2018. The primary outcomes measured were the 30-day morbidity and mortality rates. RESULTS: Twelve patients (6 men 6 women, median age 56.5 years [range 33-77 years]) underwent reoperative abdominopelvic surgery requiring the use of a native small or large seromuscular bowel flap to obliterate pelvic defects. The indications for surgery included chronic infections, fistulizing Crohn's disease, and cancer. In all cases, no residual omentum was available and rectus abdominis muscle flaps were not feasible due to prior operative scars. Thirty-day morbidity occurred in 5 patients (42%), and included urine leak from ureteral injury, anastomotic leak, acute kidney injury, and superficial surgical site infection. No flaps became ischemic or required removal in the postoperative setting. No mortality was recorded. CONCLUSIONS: Bowel seromuscular flaps are a feasible and safe alternative for covering pelvic defects in patients who are undergoing reoperative surgery without the option to use traditional omental and muscular flaps.

Disorder-induced coherent scattering in slow-light photonic crystal waveguides.

Light transmission measurements and frequency-delay reflectometry maps for GaAs photonic crystal membranes are presented and analyzed, showing the transition from propagation with a well-defined group velocity to a regime completely dominated by disorder-induced coherent scattering. Employing a self-consistent optical scattering theory, with only statistical functions to describe the structural disorder, we obtain excellent agreement with the experiments using no fitting parameters. Our experiments and theory together provide clear physical insight into naturally occurring light localization and multiple coherent-scattering phenomena in slow-light waveguides.

Metastatic malignant melanoma.

Metastatic malignant melanoma is an incurable malignancy with extremely poor prognosis. Patients bearing this diagnosis face a median survival time of approximately 9 months with a probability of surviving 5 years after initial presentation at less than 5%. This is contrasted by the curative nature of surgical resection of early melanoma detected in the skin. To date, no systemic therapy has consistently and predictably impacted the overall survival of patients with metastatic melanoma. However, in recent years, a resurgence of innovative diagnostic and therapeutic developments have broadened our understanding of the natural history of melanoma and identified rational therapeutic targets/strategies that seem poised to significantly change the clinical outcomes in these patients. Herein we review the state-of-the-art in metastatic melanoma diagnostics and therapeutics with particular emphasis on multi-disciplinary clinical management.

Free-tissue transfer experience at a county hospital.

As reimbursement for free-tissue transfer decreases, the authors find an increase in the number of free flaps performed at their county facility. Over 60 percent of the free flaps performed during the past 10 years were completed within the last 4 years. This influx of patients prompted a review of their experience with free-tissue transfer. This retrospective study of the free-flap experience at a county hospital reviewed 49 patients with 53 free flaps between 1991 and 1999. Forty-five free flaps (85 percent) were successful, with an overall failure rate of 15 percent. Most free flaps were performed on traumatic wounds. Risk factors, such as smoking, diabetes, and peripheral vascular disease, did not reliably predict free-flap failure. Irradiated, chronic wounds were associated with the highest failure rates. Seventy-five percent of the free-flap failures were due to delayed return to the operating room, once the flap appeared compromised. Delay in reexploration resulted in a zero salvage rate. Prompt recognition of failed flaps and emergent exploration will improve the success rate.

Comparison of immediate and delayed free TRAM flap breast reconstruction in patients receiving postmastectomy radiation therapy.

Tumor pathologic features and the extent of nodal involvement dictate whether radiation therapy is given after mastectomy for breast cancer. It is generally well accepted that radiation negatively influences the outcome of implant-based breast reconstruction. However, the long-term effect of radiation therapy on the outcome of breast reconstruction with the free transverse rectus abdominis myocutaneous (TRAM) flap is still unclear. For patients who need postmastectomy radiation therapy, the optimal timing of TRAM flap reconstruction is controversial. This study compares the outcome of immediate and delayed free TRAM flap breast reconstruction in patients who received postmastectomy radiation therapy. All patients at The University of Texas M. D. Anderson Cancer Center who received postmastectomy radiation therapy and who also underwent free TRAM flap breast reconstruction between January of 1988 and December of 1998 were included in the study. Patients who received radiation therapy before delayed TRAM flap reconstruction were compared with patients who underwent immediate TRAM flap reconstruction before radiation therapy. Early and late complications were compared between the two groups. Early complications included vessel thrombosis, partial or total flap loss, mastectomy skin flap necrosis, and local wound-healing problems, whereas late complications included fat necrosis, volume loss, and flap contracture of free TRAM breast mounds. Late complications were evaluated at least 1 year after the completion of radiation therapy for patients who had delayed reconstruction and at least 1 year after reconstruction for patients who had immediate reconstruction. During the study period, 32 patients had immediate TRAM flap reconstruction before radiation therapy and 70 patients had radiation therapy before TRAM flap reconstruction. Mean follow-up times for the immediate reconstruction and delayed reconstruction groups were 3 and 5 years, respectively. The mean radiation dose was 50 Gy in the immediate reconstruction group and 51 Gy in the delayed reconstruction group. One complete flap loss occurred in the delayed reconstruction group, and no flap loss occurred in the immediate reconstruction group. The incidence of early complications did not differ significantly between the two groups. However, the incidence of late complications was significantly higher in the immediate reconstruction group than in the delayed reconstruction group (87.5 percent versus 8.6 percent; p = 0.000). Nine patients (28 percent) in the immediate reconstruction group required an additional flap to correct the distorted contour from flap shrinkage and severe flap contraction. These findings indicate that, in patients who are candidates for free TRAM flap breast reconstruction and need postmastectomy radiation therapy, reconstruction should be delayed until radiation therapy is complete.

Postoperative adjuvant irradiation: effects on tranverse rectus abdominis muscle flap breast reconstruction.

The use of postoperative irradiation following oncologic breast surgery is dictated by tumor pathology, margins, and lymph node involvement. Although irradiation negatively influences implant reconstruction, it is less clear what effect it has on autogenous tissue. This study evaluated the effect of postoperative irradiation on transverse rectus abdominis muscle (TRAM) flap breast reconstruction. A retrospective review was performed on all patients undergoing immediate TRAM flap breast reconstruction followed by postoperative irradiation between 1988 and 1998. Forty-one patients with a median age of 48 years received an average of 50.99 Gy of fractionated irradiation within 6 months after breast reconstruction. All except two received adjuvant chemotherapy. Data were obtained from personal communication, physical examination, chart, and photographic review. The minimum follow-up time was 1 year, with an average of 3 years, after completion of radiation therapy. Nine patients received pedicled TRAM flaps and 32 received reconstruction with microvascular transfer. Fourteen patients had bilateral reconstruction, but irradiation was administered unilaterally to the breast with the higher risk of local recurrence. The remaining 27 patients had unilateral reconstruction. All patients were examined at least 1 year after radiotherapy. No flap loss occurred, but 10 patients (24 percent) required an additional flap to correct flap contracture. Nine patients (22 percent) maintained a normal breast volume. Hyperpigmentation occurred in 37 percent of the patients, and 56 percent were noted to have a firm reconstruction. Palpable fat necrosis was noted in 34 percent of the flaps and loss of symmetry in 78 percent. Because the numbers were small, there was no statistical difference between the pedicled and free TRAM group. However, as a group, the findings were statistically significant when compared with 1,443 nonirradiated TRAM patients. Despite the success of flap transfer, unpredictable volume, contour, and symmetry loss make it difficult to achieve consistent results using immediate TRAM breast reconstruction with postoperative irradiation. TRAM flap reconstruction in this setting should be approached cautiously, and delayed reconstruction in selected patients should be considered. Patients should be aware that multiple revisions and, possibly, additional flaps are necessary to correct the progressive deformity from radiation therapy.

Free filet extremity flap: indications and options for reconstruction.

Radical and extended forequarter and hind limb amputations have been used for curative and palliative intents. Concerns regarding wound healing and closure, especially in irradiated fields, have occasionally limited the extent of ablation. This article reports an experience with coverage of these large defects by using the free filet extremity flap. A retrospective review was performed of 11 patients who had undergone immediate reconstruction with free filet extremity flaps between 1991 and 1998. There were nine men and two women with an average age of 43.9 years. All except three patients received preoperative radiotherapy. Resections included four hindquarter and seven forequarter amputations for palliation of intractable pain, tissue necrosis, and infections. Donor vessels included the brachial artery, its venae comitantes, cephalic and basilic veins, and common femoral and popliteal vessels. Immediate reconstruction was successful in all cases by the use of the amputated limb as the free filet flap. All wounds healed despite irradiation inclusive of defects up to 50 cm x 70 cm (3500 cm2). The average follow-up time was 5 months with a mean survival of 3.5 months. Four patients currently are alive, and one patient died within 30 days of surgery. The remaining six patients have died of their disease within 9 months of the palliative procedures. Pain, tissue necrosis, and infections were improved in all patients after hospital discharge. Extensive defects can be reconstructed and healed successfully, even in irradiated wounds, with the use of the free filet extremity flap. Appropriate advanced preoperative and intraoperative planning is essential. Although survival was unchanged, this technique allowed healed wounds with an improvement in the quality of life.

Ion-molecule reactions of oxygenated chemical ionization reagents with vincamine.

The ion-molecule reactions of ions from acetone, dimethyl ether, 2-methoxyethanol, and vinyl methyl ether with vincamine were investigated. Reactions with dimethyl ether result in [M+13](+) and [M+45](+) products, reactions with 2-methoxyethanol produce [M+13](+) and [M+89](+) ions, and reactions with acetone or vinyl methyl ether ions generate predominantly [M+43](+) ions. Collision-activated dissociation and deuterium labeling experiments allowed speculation about the product structures and mechanisms of dissociation. The methylene substitution process was shown to occur at the hydroxyl oxygen and the phenyl ring of vincamine for dimethyl ether reactions, but the methylene substitution process was not favored at the hydroxyl oxygen for the 2-methoxyethanol reactions, instead favored at the 12 phenyl position. The reaction site is likely different for the 2-methoxyethanol ion due to its capability for secondary hydrogen-bonding interactions. For the [M+45](+) and [M+89](+) ions, evidence suggests that charge-remote fragmentation processes occur from these products. In general, the use of dimethyl ether ions or 2-methoxyethanol ions for ionmolecule reactions prove highly diagnostic for the characterization of vincamine; both molecular weight and structural information are obtained. Limits of detection for vincamine with dimethyl ether chemical ionization via this technique on a benchtop ion trap gas chromatography-tandem mass spectrometer are in the upper parts per trillion range.

Amphotericin B-induced changes in renal membrane permeation: a model of nephrotoxicity.

As part of an investigation into the nephrotoxic effects of the polyene antibiotic Amphotericin B we have studied its effects on the ion permeability of purified renal brush border membrane vesicles. Membrane potentials were measured using a potential sensitive carbocyanine dye, and ion permeabilities were calculated from the constant field equation. Amphotericin B significantly altered the ionic permeability sequence of isolated membranes and caused a selectivity for increasing the permeation of anions. Permeability changes induced by 2.0 micrograms/ml Amphotericin B resulted in an estimated hyperpolarization of the membrane from -50 mV to -72 mV. In addition, the kinetic parameters of Na+ dependent transport of organic metabolites were examined. The maximum change in fluorescence was decreased significantly in the presence of Amphotericin B. These results suggest that the ionic state of the renal cell membrane is significantly altered by the presence of Amphotericin B.