Electronic interactions within composites of polyanilines formed under acidic and alkaline conditions. Conductivity, ESR, Raman, UV-vis and fluorescence studies.

The properties of two forms of polyaniline (PAni) synthesised under acidic and basic conditions have been investigated both individually and as combined complexes. The PAni polymerised within alkaline media was redox inactive and non-conducting while the PAni emeraldine salt (ES) was electroactive and conducting. Raman, electron spin resonance, UV-Vis and fluorescence spectroscopies were used to monitor the changes in electronic properties of these conducting polymer composites. Solution cast films of alkaline synthesised (A-PAni) with the PAni ES resulted in an increase in the high spin polaron population suggesting that it acts as a pseudodopant. The ability of the A-PAni to increase and maintain the population of the polaron charge carrier was confirmed by UV-vis and Raman spectroscopy. Significantly, the presence of the A-PAni in PAni ES helped to sustain higher electrical conductivities at loading levels that were well below the percolation threshold of an insulating polystyrene sulfonate polymeric oligomer model. Fluorescence studies indicated that the A-PAni was fluorescent. However, mixtures of A-PAni with the PAni ES resulted in quenching of the A-PAni emission. The quenching process was observed to involve both static and dynamic processes, with the static quenching being dominant. These results suggest that the two polymers are strongly associated with each other when in the solid state. In stark contrast, the alkaline synthesized PAni did not influence the electrochemical properties of the emeraldine salt. These results deviate significantly from the expected outcome of the addition of an insulating A-PAni additive and highlight the unusual interactions occurring between PAni and its alkaline analogue.

Chemical and photoluminescence properties of purified poly(2-methoxyaniline-5-sulfonic acid) and oligomer.

Both the chemical and the electrochemical synthesis of poly(2-methoxyaniline-5-sulfonate) (PMAS) in aqueous media have been found to give two distinct polymer fractions with molecular weights of approximately 8-10 and 2 kDa, respectively. It is now possible to isolate the pure high molecular weight (HMWT) PMAS and low molecular weight (LMWT) PMAS oligomer and to study their individual and combined photochemistry and redox chemistry. The HMWT PMAS fraction was confirmed to be an emeraldine salt by its characteristic redox and pH switching behavior, in contrast to the oligomeric LMWT PMAS, which was inert under the same conditions. Mixtures of these two fractions exhibit photoluminescence arising from the oligomeric LMWT PMAS fraction. The observed LMWT PMAS emission was modulated by the presence of the conducting HMWT PMAS emeraldine salt via a static resonant energy transfer arising from quenching at 460 nm when excited at 355 nm. The nonlinear fluorophore-quencher behavior suggests that the two PMAS fractions are strongly associated. The behavior fitted the static Perrin quenching model in which the oligomeric LMWT PMAS fluorophore is diffusionally restricted by the presence of HMWT PMAS quencher.

Endoscopic carpal tunnel release.

Open carpal tunnel release has been the standard treatment of carpal tunnel syndrome for the past three decades. Since its introduction in the late 1980s, endoscopic carpal tunnel release has generated excitement and controversy. Two basic techniques have developed: the single portal and the double portal. Data from many clinical series and cadaver studies are available for review. The endoscopic carpal tunnel release offers several advantages over the standard open technique, including less scar tenderness, earlier return to work and activities of daily living, and earlier return of pinch and grip strength. Endoscopic carpal tunnel release may be safer than many of the new "mini" open techniques. The indications and threshold for surgery are the same in both techniques. The major contraindications are rheumatoid arthritis, mass lesions, and repeat surgery. Many adjunctive procedures done with open carpal tunnel release such as exploration of the motor branch, release of Guyon's canal, epineurotomy or neurolysis, and flexor tenosynovectomy are unnecessary. With proper training and equipment, endoscopic carpal tunnel release can be done safely, with complication rates comparable to those for the open technique and with high patient satisfaction.

Office evaluation and treatment of finger and hand injuries in children.

Injury is our children's greatest health problem, and pediatricians will frequently see finger and hand injuries in the office and emergency room. Many of these will be fingertip crush injuries, which are quite common in toddlers and are often undertreated. Pediatric finger and wrist fractures and sprains generally do well but require proper diagnosis and treatment. Innocent-looking wounds from glass lacerations may disguise extensive damage to underlying nerves, arteries, and tendons. Advances in microsurgery allow replantation of distal amputations even in young children and infants, although often not without complications. Thermal injuries and animal bites require early and aggressive treatment. As with many pediatric hand injuries, these injuries should be preventable, and the adverse consequences can be minimized with appropriate diagnosis and management.

Vascularized bone allografts: in vitro assessment of cell-mediated and humoral responses.

The immunologic consequences of transplantation of vascularized bone allografts have not been previously characterized. In this study, knee allografts, both vascularized and nonvascularized, were transplanted from Lewis rats to Brown Norway rats across a strong histocompatibility barrier. A total of 66 transplants and 8 control animals were evaluated. The vascularized knee grafts consisted of 1 cm of proximal tibia and distal femur with a minimal muscular cuff isolated on the femoral vessels, and these were transplanted to a heterotopic, subcutaneous position on the abdominal wall of the recipient rat. Nonvascularized allografts (identical but without anastomoses) were transplanted for comparison. The cell-mediated response was measured by lymphocytotoxicity assay, and the humoral response was measured by cytotoxic antibody assay, both employing 51Cr-labeled target cells. The timing and intensity of the immune response differed according to the type of graft. The vascularized bone allografts generated significant cell-mediated and humoral responses as early as 5 days posttransplant. A significant humoral response in nonvascularized bone allografts was not apparent until day 14, while cell-mediated response in these grafts was variable. These findings were correlated with the histologic appearance of the grafted tissue. Cyclosporine, which was administered to one group of vascularized bone allografts, resulted in the suppression of both types of immune responses. The histologic appearance of this group resembled that of isografts transplanted as controls. The clinical application of vascularized bone allografts may offer significant advantages over nonvascularized allografts in the reconstruction of massive bone defects. Complications such as nonunion, fracture, and collapse of articular segments seen in nonvascularized allograft transplantation may be avoided by preservation of the blood supply to the graft. Characterization of the immune response to vascularized bone allografts may subsequently allow the manipulation of the host and/or graft tissue and promote graft incorporation.

Weightbearing roentgenograms in arthritis of the ankle: a case report.

In specific situations the nonweightbearing roentgenograms of the ankle do not correlate with clinically suspected ankle malalignment or arthrosis, and weightbearing roentgenograms of the ankle joint can be quite helpful. The nature and severity of ankle arthrosis may not be detected with standard x-rays alone. A case is described in which these views contributed significantly to the clinical treatment of a rheumatoid patient.