DEER-Stitch: combining three- and four-pulse DEER measurements for high sensitivity, deadtime free data.

Over approximately the last 15 years the electron paramagnetic resonance (EPR) technique of double electron electron resonance (DEER) has attracted considerable attention since it allows for the precise measurement of the dipole-dipole coupling between radicals and thus can lead to distance information between pairs of radicals separated by up to ca. 8 nm. The "deadtime free" 4-pulse DEER sequence is widely used but can suffer from poor sensitivity if the electron spin-echo decays too quickly to allow collection of a sufficiently long time trace. In this paper we present a method which takes advantage of the much greater sensitivity that the 3-pulse sequence offers over the 4-pulse sequence since the measured electron spin-echo intensity (for equal sequence lengths) is greater. By combining 3- and 4-pulse DEER time traces using a method coined DEER-Stitch (DEERS) accurate dipole-dipole coupling measurements can be made which combine the sensitivity of the 3-pulse DEER sequence with the deadtime free advantage of the 4-pulse DEER sequence. To develop the DEER-Stitch method three systems were measured: a semi-rigid bis-nitroxide labeled nanowire, the bis-nitroxide labeled protein CD55 with a distance between labels of almost 8 nm and a dimeric copper amine oxidase from Arthrobacter globiformis (AGAO).

Structural information from orientationally selective DEER spectroscopy.

Double electron-electron resonance (DEER) spectroscopy can determine, from measurement of the dipolar interaction, the distance and orientation between two paramagnetic centres in systems lacking long-range order such as powders or frozen solution samples. In spin systems with considerable anisotropy, the microwave pulses excite only a fraction of the electron paramagnetic resonance (EPR) spectrum and the resulting orientation selection needs to be explicitly taken into account if a meaningful distance and orientation is to be determined. Here, a general method is presented to analyze the dipolar interaction between two paramagnetic spin centres from a series of DEER traces recorded so that different orientations of the spin-spin vector are sampled. Delocalised spin density distributions and spin projection factors (as for example in iron-sulfur clusters), are explicitly included. Application of the analysis to a spin-labelled flavoprotein reductase/reduced iron-sulfur ferredoxin protein complex and a bi-radical with two Cu(ii) ions provides distance and orientation information between the radical centres. In the protein complex this enables the protein-protein binding geometry to be defined. Experimentally, orientationally selective DEER measurements are possible on paramagnetic systems where the resonator bandwidth allows the frequencies of pump and detection pulses to be separated sufficiently to excite enough orientations to define adequately the spin-spin vector.

Analysis of nitric oxide activity in prevention of reperfusion injury.

This project was designed to determine the role of nitric oxide (NO) in the prevention of ischemia-reperfusion injury. Inferiorly based rectus abdominis muscle flaps were elevated in pigs and subjected to 6 hours of ischemia followed by 4 hours of reperfusion. Group I animals received a bolus of L-arginine before reperfusion, and a continuous infusion once flow was restored. Group II animals served as controls and received an equal volume of saline as a bolus and subsequent continuous infusion. Microdialysis was used to measure tissue NO levels, and these were correlated with muscle survival determined by vital staining with nitroblue tetrazolium. The results demonstrated a significant increase in tissue NO levels in L-arginine-supplemented animals (p < 0.05), which in turn correlated with a significant increase in muscle survival (p = 0.0051). These results suggest that administration of supplemental L-arginine to ischemic skeletal muscle during reperfusion results in increased NO production and decreased tissue damage.

Postoperative ramifications of total ear replantation.

Complete avulsion of the external ear, much less common than other minor ear trauma, presents a complex and difficult problem. The authors present a 35-year-old male cigarette smoker who suffered traumatic avulsion of the right ear, and describe the replantation procedure and the patient's postoperative course. Aesthetic positioning of the replanted ear, treating the external auditory meatus, protecting the ear against exposure to the sun, and counseling the patient about issues related to sensation are important factors in the care of patients who have undergone such a procedure.

Subungual keratoacanthoma masquerading as a chronic paronychia.

Subungual keratoacanthoma is a rare, benign tumor of the digits. Patients present with progressive fusiform swelling, erythema, and tenderness, usually affecting a single digit on the radial side of the hand. A cup-shaped lytic lesion of the distal phalanx is a uniform finding on radiography. Delay in diagnosis and misdiagnosis are common because of the rarity of the lesion and difficulties with histological differentiation from subungual squamous cell carcinoma. Accurate diagnosis requires a high index of suspicion, a careful history, and histological evaluation. The natural progression of the disease appears to be continued growth with ongoing destruction of the distal phalanx. Proper treatment involves surgical removal of the mass by curettage and close follow-up for at least 2 years to monitor for local recurrence.

Analysis of lower extremity blood flow in the patient with peripheral vascular insufficiency: a guide for plastic surgeons.

Accurate assessment of lower extremity blood flow is critical in selecting appropriate therapy for patients with peripheral vascular disease and nonhealing wounds. Although physical examination provides an idea about the extent and significance of the disease, further evaluation, including both noninvasive and invasive studies, is routinely obtained. Appropriate studies will provide valuable information about the location and severity of disease, the need for revascularization before definitive wound coverage, and the likelihood of wound healing. A brief overview of vascular laboratory tests, highlighting the values and limitations of each, is presented here.

Distance and the use of mental health services.

The inverse relationship between distance from mental health services and their use has been noted over many decades and on several continents. Although many factors--diagnostic, socioeconomic, and nosocomial--may modify this correlation, its persistence is remarkable. As other barriers to use are diminished, distance remains a mutable variable for planning more effective use of many health care services.

Organizationally sponsored health services research.

Organizations, particularly large multi-institutional health delivery systems, have begun to sponsor their own research programs as a consequence of the scope and complexity of management and governance decisions they face. These research programs are functionally integrated into the organization and serve as a strategic management planning and decision-making tool. Their primary purpose is seen to be the comprehension, analysis, synthesis, application, and evaluation of the vast amount of information available within the organization and from the health delivery system. Their emphasis is on making research results relevant to organizational goals and objectives, applicable to organizational decisions, and utilized. Organizationally sponsored researchers, it has been shown, face a particularly complex set of management and research requirements in building their programs. Developing the research agenda and establishing an infrastructure for the conduct of research are critical to success. Once accomplished, the organizationally sponsored researcher does have particular advantages in conducting the research and in seeing the findings used to improve health care delivery. We have cited and addressed a number of concerns or issues relating to the emergence of organizationally sponsored research. Some are specious in origin; others arise out of an incomplete understanding of the systems of evaluation and reward which have traditionally applied to professional researchers. It is in terms of the intended beneficiary of the research and the extent to which the results are made to apply directly to the organizational manager that differences emerge--not in the quality or quantity of research accomplished, in the use of inductive or deductive approaches, or in the objectivity of results.

A multihospital medication allergy audit: a means to quality assurance.

Seventeen community hospitals within the 16 division of the Sisters of Mercy Health Corporation cooperatively participated in a medication allergy audit program. Initial and follow-up audits were conducted at each hospital to determine whether allergy information for penicillin- or aspirin-sensitive patients was appropriately communicated to the pharmacist. A total of 483 patient records were reviewed during each audit which corresponded to 12% of each hospital's average patient census. In the initial audit, the overall acceptance rate for the combined hospitals was 62.3%. Following the first audit, each hospital undertook corrective follow-up measures in an attempt to improve its results. In the second audit, the overall acceptance rate improved significantly to 78.9%. It is concluded that this auditing process followed by corrective follow-up measures was an effective mechanism for improving the communication of patient allergy information and is a means to quality assurance. Future audits will be necessary to determine whether the beneficial effects produced will be sustained or improved.