Initial Studies Directed toward the Rational Design of Aqueous Graphene Dispersants.

This study presents preliminary experimental data suggesting that sodium 4-(pyrene-1-yl)butane-1-sulfonate (PBSA), 5, an analogue of sodium pyrene-1-sulfonate (PSA), 1, enhances the stability of aqueous reduced graphene oxide (RGO) graphene dispersions. We find that RGO and exfoliated graphene dispersions prepared in the presence of 5 are approximately double the concentration of those made with commercially available PSA, 1. Quantum mechanical and molecular dynamics simulations provide key insights into the behavior of these molecules on the graphene surface. The seemingly obvious introduction of a polar sulfonate head group linked via an appropriate alkyl spacer to the aromatic core results in both more efficient binding of 5 to the graphene surface and more efficient solvation of the polar head group by bulk solvent (water). Overall, this improves the stabilization of the graphene flakes by disfavoring dissociation of the stabilizer from the graphene surface and inhibiting reaggregation by electrostatic and steric repulsion. These insights are currently the subject of further investigations in an attempt to develop a rational approach to the design of more effective dispersing agents for rGO and graphene in aqueous solution.

Non-linear, cata-Condensed, Polycyclic Aromatic Hydrocarbon Materials: A Generic Approach and Physical Properties.

A generic approach to the regiospecific synthesis of halogenated polycyclic aromatics is made possible by the one- or two-directional benzannulation reactions of readily available (ortho-allylaryl)trichloroacetates (the "BHQ" reaction). Palladium-catalysed cross-coupling reactions of the so-formed haloaromatics enable the synthesis of functionalised polycyclic aromatic hydrocarbons (PAHs) with surgical precision. Overall, this new methodology enables the facile mining of chemical space in search of new electronic functional materials.

Enhancement of CO2 Affinity in a Polymer of Intrinsic Microporosity by Amine Modification.

Nitrile groups in the polymer of intrinsic microporosity PIM-1 were reduced to primary amines using borane complexes. In adsorption experiments, the novel amine-PIM-1 showed higher CO2 uptake and higher CO2/N2 sorption selectivity than the parent polymer, with very evident dual-mode sorption behavior. In gas permeation with six light gases, the individual contributions of solubility and diffusion to the overall permeability was determined via time-lag analysis. The high CO2 affinity drastically restricts diffusion at low pressures and lowers CO2 permeability compared to the parent PIM-1. Furthermore, the size-sieving properties of the polymer are increased, which can be attributed to a higher stiffness of the system arising from hydrogen bonding of the amine groups. Thus, for the H2/CO2 gas pair, whereas PIM-1 favors CO2, amine-PIM-1 shows permselectivity toward H2, breaking the Robeson 2008 upper bound.

What opportunities have we missed, and what bad deals have we made?

In addition to its many accomplishments, family medicine has inevitably made some choices that have not worked out as well. Respectful consideration of where we may have done so can help inform future decision making. This paper suggests some decisions that in retrospect appear to be bad deals, good deals gone bad, or missed opportunities. Bad deals include the limiting effects of our specialty's name and of our go-it-alone philosophy. Good deals gone bad include our affinity for a permanent counterculture role, our persistent belief that big is better, and limited evolution of our residency family practice centers. We have missed opportunities to lead development of a new model of patient-responsive health care, to change the system of payment for care, to maximize the strength of our discipline by links between university and community family physicians, and to build a powerful program of family medicine research.

Familial gigantiform cementoma.

Familial gigantiform cementoma is a rare autosomal dominant tumor that is benign but can result in disfigurement of the facial skeleton. Two families with a total of five patients presented for treatment. Because of a lack of opportunity to obtain treatment early, three of the patients presented in adult life with massive tumors requiring extensive resection and complex reconstruction in multiple stages. The two female patients had chronic anemia caused by multifocal polypoid adenomas of the uterus and required hysterectomy before treatment. The last three patients had elevated alkaline phosphatase levels before tumor resection, and these levels decreased after surgery. With extensive resection of the tumors and reconstruction of both the soft tissues and facial skeleton, good functional and aesthetic results can be obtained. There has been no tumor recurrence with 3 years of follow-up.

Sweat gland carcinoma: a clinicopathologic analysis of an expanded series in a single institution.

Primary adenocarcinoma of sweat glands is a rare tumor; approximately 220 cases have been reported in the last 30 years. We reviewed the charts of patients with primary diagnosis of this tumor treated at the Mayo Clinic between 1935 and 1995. We included only cases with initial histology slides available for re-examination. Tumors were classified into five recognizable histologic patterns (solid, ductal, mucinous, microcystic adnexal, and adenocystic carcinoma) and graded by the Broder system. Statistical analysis consisted of Kaplan-Meier product limit method and Cox multiple regression test. In total, 55 patients were identified, and age ranged from 13 to 85 years (mean 59 years). Thirty-six patients (65 percent) presented to the Mayo Clinic for initial treatment; all except one had disease limited to the primary site. Microcystic adnexal carcinoma was the most frequent type, and more than 50 percent were grade 2 tumors. Among these 36 patients, 4 had some type of recurrence. Patients who developed metastasis had a high-grade tumor in the initial biopsy. Nineteen patients were referred with recurrence; 13 had local recurrence, 4 had regional diseases, and 2 had distant metastases. The histologic distribution showed 47 percent solid tumors, and 37 percent of them were grade 3. Multiple regression analysis did not show a difference in recurrence or survival when gender, age, tumor location, or histologic pattern was evaluated. In addition, there was no difference in the outcome between wide surgical resection and micrographic surgery. The only predictive factor for distant metastases and/or death (p < 0.003) was histologic grade. Overall 10-year survival rate was 86 and 60 percent for primary and referred patients, respectively. We conclude that histologic diagnosis of sweat gland carcinoma must be complemented by clinical examination to evaluate metastases. Clinical behavior depends on the histologic type of tumor, degree of differentiation, and clinical stage. On recurrence, the likelihood of further recurrences and mortality increases dramatically. Aggressive initial local ablation with tumor-free margins is recommended. In high-grade tumors, prophylactic regional lymph node dissection may further characterize tumor aggressiveness and may justify adjuvant radiotherapy as part of the primary treatment.

Treatment outcome for 424 primary cases of clinical I cutaneous malignant melanoma of the head and neck.

BACKGROUND: Cutaneous malignant melanoma (CMM) is increasing in frequency. Surgery remains the primary and only curative treatment method. Our aim was to define prognostic factors and outcome predictors for patients with clinical stage I CMM of the head and neck. METHODS: Surgical treatment and outcome was analyzed for 424 patients with clinical stage I melanoma of the head and neck, completing initial treatment at the Mayo Clinic (1970-1990). The data were analyzed using the Kaplan-Meier product-limit method and Cox multiple-regression models. RESULTS: Overall, 180 (42%) patients underwent elective lymph node dissection (ELND) as part of the initial treatment; occult disease was demonstrated in 15 (8.3%). Among patients with tumor > 1.5 mm thick, occult regional disease was found in 15%. Failure of final treatment occurred in 152 (36%). Overall, 82% and 75% of the patients survived 5 and 10 years, respectively. CONCLUSIONS: Tumor thickness, extent of invasion, and the presence of occult region metastatic disease were the only independently predictive value (p < .005) of recurrence. The detection of disease by ELND did not appear to protect the patient from disease progression but identified those with regionally advanced disease and highest risk for recurrence. The development of recurrence significantly reduced but did not eliminate the potential for extended disease-free survival with subsequent treatment.

The uremic gangrene syndrome: improved healing in spontaneously forming wounds following subtotal parathyroidectomy.

Patients with end-stage renal disease often demonstrate retarded healing of surgical wounds, but the basis for spontaneous wound formation in these patients is less well understood. We report our experience with four patients with a unique clinical entity previously described as the uremic gangrene syndrome (also known as calciphylaxis) that involves spontaneously forming and insidiously progressive wounds of the skin and soft tissue in uremic patients with hyperparathyroidism. The importance of recognizing this phenomenon relates to the potential benefit to wound-healing efforts resulting from subtotal parathyroidectomy and adjustment of serum calcium and phosphate levels when severe hyperparathyroidism is present. Disrupted parathyroid homeostasis as a mechanism for soft-tissue ischemia and subsequent infarction is supported by wound biopsies demonstrating microarterial calcification. As experts in factors resulting in refractory wounds, plastic surgeons need be aware of this peculiar vulnerability for spontaneously forming wounds in uremic patients. Clinical and laboratory findings, success with wound treatment in four patients, and currently popular pathophysiologic mechanisms are discussed.

Enhanced bone graft contouring for mandibular reconstruction using intraoperatively fashioned templates.

Among the challenges created by reconstruction of mandibular defects using free vascularized bone flaps is sizing and contouring of the bone graft in accordance with the dimensions of the defect. We have developed a rapid and reliable method for constructing a postablative template of the defect using a rapid-setting splint material called Aquaplast. The template can then be used at a site remote from the head and neck as a precise model of the defect for optimal size and shape estimation during bone graft sculpting and fixation. The material also has postablative utility for estimation of internal lining requirements and soft-tissue replacements during osteomusculocutaneous or fasciocutaneous flap planning. We feel that the use of Aquaplast has greatly enhanced our three-dimensional appreciation of mandibular bone defects and enhanced the final aesthetic and functional results in our patients undergoing mandibular reconstruction.

Significant hemangiomas and vascular malformations of the head and neck: clinical management and treatment outcomes.

The treatment dilemmas and our institutional experience with head and neck hemangiomas and vascular malformations are reviewed. Fifty-eight patients (38 with hemangiomas, 20 with vascular malformations) aged from newborn to 78 years were treated from 1975 to 1993. Eighty-seven percent of patients provided up-to-date follow-up, yielding a median follow-up interval of 7.18 years from intervention. Only significantly sized tumors (minimum diameter > 4 cm) were studied. Sodium tetradecyl sulfate sclerotherapy (SDS) was a sole therapy in 12 patients (all with hemangiomas) and was used in combination with surgical ablation in 22 patients (16 with hemangiomas, 6 with vascular malformations). The minority of tumors from both categories were completely removed with ablative surgery (six hemangiomas [23%], eight vascular malformations [44%]). Significantly debilitating tumor postsurgical recurrence, which led to mortality in some patients, was unique to vascular malformations with high flow on the basis of increased arterial to venous shunting. Less alarming but significant functional and cosmetic challenges are created in primarily postadolescent patients with incompletely involuted hemangiomas and low-flow vascular malformations of the head and neck. We have had a favorable experience with the combined application of sclerotherapy and conservative ablative surgery in this group. Patient survey implied satisfaction with treatment in the majority: Nine indicated they benefited significantly (17%); 37 indicated they were generally improved (71%); and 6 stated they did not benefit (12%). Tumor-specific philosophy on ablative therapy, recurrence patterns, and associated complications are presented.

Real-time simultaneous wide- and small-angle fibre diffraction.

A combination of two independent imaging area-detector systems controlled by a single data-acquisition system, provides a powerful system for X-ray diffraction studies of time-resolved phenomena over a wide q range, in samples with intrinsic or induced structural orientation. With this system we have observed a transient, tensile-stress-induced, orthorhombic-to-monoclinic transition in high-density polyethylene.

The effect of tissue expansion on the random flap viability and wound tensile strength of previously irradiated rabbit skin.

Tissue expansion facilitates coverage of cutaneous defects both through the generation of additional skin surface area and by increasing random flap length/width viability factors. The opportunity to apply tissue expansion techniques to head and neck defects within previously irradiated skin fields continues to increase. To study the effect of tissue expansion on the cutaneous perfusion and wound-healing capacity of irradiation-damaged skin, rabbit scalps were subjected to 5 weeks of fractionated radiation followed at 4 months by prolonged tissue expansion. Standardized random flaps were then created and reset within the expanded skin and analyzed in parallel with nonirradiated and nonexpanded control animals. Flap viability as expressed by area and mean maximum length was determined at 10 days postwounding followed by determination of wound-breaking strength. Irradiated tissues demonstrated a significantly reduced flap viability that was significantly increased by expansion. However, tissue expansion-related increases in flap length exceeded those expressed as percent of total area surviving for irradiated animals. Tissue expansion resulted in significant increases in wound tensile strength only in nonirradiated animals. These findings suggest that, compared with controls, several of the benefits of tissue expansion are less appreciable in radiation-damaged skin.

Diet and exercise and gemfibrozil therapy for the management of dyslipidemia: a CEN study. Clinical Experience Network.

BACKGROUND: Dyslipidemia constitutes a serious health problem that should be diagnosed and treated by the family physician. Little is known about the efficacy of typical dietary therapy for patients with abnormal cholesterol levels. This study was the first large prospective family practice evaluation of the effectiveness of diet-and-exercise therapy followed by a pharmacologic intervention for those patients who remained dyslipidemic. METHODS: Patients who met standard criteria for cardiovascular disease risk based on lipid analysis were enrolled in a typical 6-week physician-directed diet-and-exercise program. Those patients who were still dyslipidemic after that period were started on 12 weeks of pharmacologic treatment with gemfibrozil. RESULTS: Of the 2992 patients screened, 1193 were eligible for participation in the study. The diet-and-exercise program led to a modest change in lipid values (average decrease in total cholesterol of 4.1%). Only 2% of the patients achieved desirable levels of all lipid values. Seven hundred thirty-nine subjects qualified for further therapy and were treated with gemfibrozil. Seventy patients discontinued drug therapy because of adverse effects. Those who completed 12 weeks of pharmacologic therapy had an additional 5.4% reduction in total cholesterol, 3.9% reduction in low-density lipoprotein cholesterol, 30.6% reduction in triglycerides, and a 17.2% increase in high-density lipoprotein cholesterol. CONCLUSIONS: These findings suggest that in a typical clinical setting, a nonpharmacologic intervention of diet and exercise may not produce the desired overall lipid changes in the majority of dyslipidemic patients.

The effect of tissue expansion on previously irradiated skin.

Opinion remains divided over the advisability of tissue expansion in previously irradiated skin. We examined the properties of, and complications associated with, tissue expansion in previously irradiated rabbit scalps. Irradiation injury was produced using fractionated roentgen rays, with a total dose of 5000 cGy over a 5-week interval. Following a 20-week convalescence interval, expansion was incrementally conducted over 4 weeks. Monitored parameters included cutaneous perfusion as indicated by fiberoptic dermofluorometry, intraluminal pressure, linear surface gain, and area of surface necrosis. The incidence and severity of complications, including surface necrosis, were significantly higher among irradiated animals. Furthermore, the overlying skin of irradiated animals demonstrated a significantly decreased compliance and measurable area gain. Given the inferior expansibility and higher tendency toward complications with contemporary expansion techniques in previously irradiated skin, alternate reconstructive options are preferable in this setting.

Primary parotid malignancies. A clinical and pathologic review.

One hundred ninety-four patients with primary malignant tumors of the parotid gland who underwent surgery at the Mayo Clinic (1970 through 1987) are reviewed. Survival patterns were analyzed using the Kaplan-Meier product-limit method that separated histologic results into three significantly different groups. Survival rate was highest for patients with acinic cell, adenoid cystic, and low-grade mucoepidermoid carcinomas; intermediate for patients with high-grade mucoepidermoid carcinomas; and lowest for the remaining six histologic types encountered. Cox multiple linear regression was used to identify patient and tumor characteristics with greatest prognostic significance. In order of decreasing strength, regional metastatic involvement, pain, male gender, grade, stage, and advancing age all demonstrated independent prognostic significance. Fifty-three percent of patients requiring facial nerve sacrifice were asymptomatic at presentation. A high positive correlation was observed between advancing grade and stage.