Capsulorrhaphy through an anterior approach for the treatment of atraumatic posterior glenohumeral instability with multidirectional laxity of the shoulder

Between June 1983 and March 1992, we performed a capsular reconstruction procedure through an anterior approach in ten patients (ten shoulders) who had multidirectional laxity of the shoulder and symptomatic atraumatic posterior glenohumeral instability. The procedure included closure of the capsule in the rotator interval and imbrication of the anterior, inferior, and posteroinferior aspects of the capsule by a double-breasting technique that decreases the overall capsular volume. The mean duration of follow-up was sixty months (range, twenty-four to 103 months). According to the system of Rowe and Zarins, the result was graded as excellent for five shoulders, good for four, and poor for one. On the basis of our results, we recommend capsular reconstruction through an anterior approach only in patients who have persistent multidirectional laxity and symptomatic atraumatic posterior instability of the shoulder despite participation in an intensive rehabilitation program.     

Incorporation of a venturi device in electrospray ionization

Electrospray ionization has grown to be one of the most commonly used ionization techniques for mass spectrometry, and efforts continue to improve its performance. Typically, the sprayer tip must be very close to the entrance orifice of the mass spectrometer in order to maximize the conduction of ions from the sprayer into the mass spectrometer. However, because of space-charge repulsion, most ions never reach the sampling orifice. In this work, an industrial air amplifier, for which the working mechanism is based on venturi and coanda effects, was added between an electrospray ionization source and a time-of-flight mass spectrometer. When a series of reserpine solutions (0.5, 1.0, 5.0, and 10.0 microM) were monitored using mass spectrometry, an over 5-fold increase in m/z 609.3 ion intensity was measured for a separation distance of 14 mm between the electrospray tip and interface capillary inlet, as compared to when the electrospray tip was in its normal position 1 mm in front of the inlet without the amplifier. When a voltage was applied to the air amplifier to further assist in focusing the electrosprayed ions, an approximately 18-fold increase in m/z 609.3 ion intensity was obtained. In addition, a 34-fold reduction in method detection limit was observed.     

A Generalized Scanning Technique for Display of Parametrically Defined Surfaces

Special attention is given to the adaptation of the technique for efficiency to both polynomial and rational Bezier patches. The resulting algorithms are simple and robust. Their speed depends mainly on the surface area of the object being rendered, not on the number of surface patches. The technique is particularly suitable for rapid display of geometrically complex objects. Since the technique directly renders from the definitions of the surfaces without needing polygons, it can maintain a relatively compact database. Several examples with timing are included. The technique described creates smooth, shaded images for parametrically defined surfaces. It depends on a general surface scan to generate a dense set of points that represents the surface. Hidden surfaces are eliminated by sorting the sample points into a z-buffer and retaining the points nearest the viewer. Alternative schemes are given for computing the surface normal for each point in the z-buffer. Conventional illumination routines can then be applied to determine the intensities at each pixel, although the reflection-mapping technique is preferred for this article.     

Aging-related clinical and health services research in Canada

Penetrating injuries, by definition, result in retained bullets or fragments. Usually, these fragments are removed surgically during wound debridement. Occasionally, the position of the bullet may preclude removal if it is thought that surgery could exacerbate neurologic damage. Complications from retained fragments are uncommon. One rare complication is the spontaneous migration of the fragment. Two cases of spontaneous migration of retained bullets are presented. In both cases neurologic deterioration was noted and computed tomographic imaging was diagnostic. In one case, this complication delayed transfer from the acute care hospital to rehabilitation. In the other case, the migrating bullet was removed during the inpatient rehabilitation stay. Each person improved neurologically after the migrating bullet fragment was removed. Additionally, functional progress was marked in both persons and symptomatic relief noted. Rehabilitation physicians caring for survivors of penetrating brain injuries need to be aware of this potentially devastating phenomenon.     

Electron ionization in superimposed magnetic and radio frequency quadrupolar electric fields

An improved design of a novel electron ionization source for orthogonal acceleration time-of-flight mass spectrometry is described, based on the superimposition of an axial magnetic field with cylindrical symmetry around a radio frequency-only quadrupole. A tubular permanent magnet was designed to generate the required strong magnetic field and field profile. An axial electric field along the ion guide for efficient ion extraction was introduced using segmented quadrupole rods. Details of the source design and the effects of various operating parameters are described. The source produces high-quality mass spectra with regard to fragmentation, relative abundances, and isotopic ratios. Preliminary results have shown excellent sensitivity, with limits of detection in the subfemtogram range (octafluoronaphthalene, full spectrum acquisition) in gas chromatography/mass spectrometry operation.     

Visualization of solid reaction-diffusion systems

In 1952, mathematician Alan Turing introduced reaction diffusion. This mechanism permits large-scale features to emerge in the concentrations of chemicals that react and diffuse within an array of reaction sites, or cells. Recently, we used a cellular automaton-based reaction-diffusion system to generate textures for computer graphics applications. We extended the original binary nature of cellular automata to encompass multiple scalar variables, increasing the range and variety of patterns generated     

Subcortical vascular dementia: survey of treatment patterns and research considerations

OBJECTIVE: The purpose of this study was to evaluate retrospectively the efficacy of a proposed panel of three cardiac markers (myoglobin, creatine kinase-MB mass [CK-MB], and cardiac troponin I) in the diagnosis of acute myocardial infarction (AMI) in patients with atraumatic chest pain. DESIGN: A total of 110 patients admitted for the evaluation of atraumatic chest pain were examined. Forty-one of these patients were diagnosed with AMI. RESULTS: Five of the 41 patients with AMI had abnormally elevated myoglobin levels, whereas values of CK-MB and/or cardiac troponin I remained negative. Creatine kinase-MB mass alone had a sensitivity of 92.7%, a specificity of 89.9%, a positive predictive value of 84.4%, and a negative predictive value of 95.0% for the diagnosis of AMI. Cardiac troponin I alone had a sensitivity of 90.2%, a specificity of 95.7%, a positive predictive value of 92.5%, and a negative predictive value of 94.3% for the diagnosis of AMI. Cardiac troponin I is a more specific marker for the diagnosis of AMI than CK-MB, particularly in patients with chronic renal failure who are evaluated for chest pain. The combination of CK-MB and cardiac troponin I increased the sensitivity to 100% and the negative predictive value to 100% and had a specificity of 88.4% and a positive predictive value of 83.7%. The panel was diagnostic for all patients with AMI within 12 hours after admission. CONCLUSIONS: Our preliminary results indicate that this panel is highly effective for evaluation of AMI in patients with atraumatic chest pain. Elevated myoglobin levels were useful in detecting patients at high risk for AMI who initially were not detected with other markers. The combination of CK-MB and cardiac troponin I provided much higher sensitivity and had a much higher negative predictive value for the evaluation of AMI than cardiac troponin I or CK-MB alone. The 100% negative predictive value is particularly important because it indicates that patients with negative CK-MB and cardiac troponin I values 12 hours after admission have a negligible likelihood of AMI.