Cervical spinal cord compression and the Hoffmann sign.

Little information exists about the ability of the Hoffmann sign to predict cervical spinal cord compression. The objective of this study was to determine the correlation between the Hoffmann sign and cervical spinal cord compression in a consecutive series of patients seen by a single spine surgeon. All new patients with complaints related to their cervical spine were included. Hoffmann sign was elicited by flicking the nail of the middle finger. Any flexion of the ipsilateral thumb and/or index finger was considered positive. All imaging studies were reviewed for spinal cord compression. Cord compression was defined as flattening of the AP diameter of the spinal cord coexisting with obliteration of CSF around the cord compared to normal levels. Of 165 patients, 124 patients had imaging of their spinal canal. Review by the spine surgeon found sensitivity of the Hoffmann sign relative to cord compression was 58%, specificity 78%, positive predictive value 62%, negative predictive value 75%. 49 studies were also read by a "blinded" neuroradiologist, the sensitivity was 33%, specificity 59%, positive predictive value, 26%, negative predictive value 67%. Although attractive as a simple method of screening for cervical spinal cord compression, the Hoffmann sign, in the absence of other clinical findings, is not in our experience a reliable test.

Glenohumeral instability.

Glenohumeral instability can be defined as pain associated with loss of shoulder function due to excessive translation of the humeral head on the glenoid fossa. It can be classified according to many factors, such as direction, degree, mechanism, and frequency. A thorough understanding of the anatomy and biomechanics of the shoulder joint as they relate to instability is helpful in understanding the pathophysiology of this condition. All components of the instability must be correctly diagnosed so that appropriate treatment can be selected. Clinical examination is most important in making the correct diagnosis, but plain radiographs, arthrography, computed tomography, magnetic resonance imaging, examination under anesthesia, and arthroscopy can be helpful in difficult and challenging cases. Conservative treatment with a rehabilitation program can be successful in a large percentage of cases and should be the initial approach for most patients. Operative treatment is based on the direction and type of instability and is recommended only after an adequate trial of conservative therapy has failed to improve recurrent instability.

(1-->3)-beta-d-Glucan Synthase from Sugar Beet : II. Product Inhibition by UDP.

The mode of inhibition of UDP, one of the products of the reaction catalyzed by (1-->3)-beta-d-glucan synthase in sugar beet (Beta vulgaris L.) was investigated. In the absence of added UDP, the enzyme, in the presence of Ca(2+), Mg(2+), and cellobiose, exhibited Michaelis-Menten kinetics and had an apparent K(m) of 260 micromolar for UDP-glucose. Complex effects on the kinetics of the (1-->3)-beta-d-glucan synthase were observed in the presence of UDP. At high UDP-glucose concentrations, i.e. greater than the apparent K(m), UDP behaved as a competitive inhibitor with an apparent K(i) of 80 micromolar. However, at low UDP-glucose concentrations, reciprocal plots of enzyme activity versus substrate concentration deviated sharply from linearity. This unusual effect of UDP is similar to that reported for fungal (1-->3)-beta-d-glucan synthase. However, papulacandin B, a potent inhibitor of this fungal enzyme, had no effect on the plant (1-->3)-beta-d-glucan synthase isolated from sugar beet petioles. The inhibitory effect of UDP was also compared with other known inhibitors of glucan synthases.

(1-->3)-beta-d-Glucan Synthase from Sugar Beet : I. Isolation and Solubilization.

A (1-->3)-beta-glucan synthase has been isolated from petiole tissue of sugar beet (Beta vulgaris L.). Enzyme activity is associated with a membrane fraction with a density of 1.03 grams per cubic centimeter when subjected to isopycnic density gradient centrifugation in Percoll. The reaction product was determined to be a linear (1-->3)-beta-glucan by methylation analysis and by glucanase digestion. (1-->3)-beta-Glucan synthase activity is markedly stimulated by Ca(2+); activation is half-maximal at about 50 micromolar Ca(2+) and is nearly saturated at 100 micromolar. Other divalent cations tested, Mg(2+), Mn(2+), and Sr(2+), also stimulate enzyme activity but are less effective. Enzyme activity was also stimulated up to 12-fold by beta-glucosides. Sirofluor, the fluorochrome from aniline blue, inhibited enzyme activity 95% when included at 1 millimolar. The enzyme was solubilized in Zwittergent 3-14; 85% of total enzyme activity was solubilized in 0.03% detergent and the optimal detergent-to-protein ratio was 0.3 at 3 milligrams per milliliter protein.

Rapid detection of group B streptococcal antigen by monoclonal antibody sandwich enzyme assay.

Group B Streptococcus (GBS) is the most common cause of neonatal sepsis and meningitis. Infants at greatest risk to develop invasive disease are delivered to women colonized with GBS in their birth canals and lacking immunity to the colonizing serotype. We have investigated the sensitivity and specificity of a recently developed monoclonal antibody sandwich enzyme immunoassay for detection of GBS antigen. The sandwich enzyme immunoassay detected types II and III GBS at a concentration of 5 X 10(4) CFU/ml and types Ia and Ib GBS at 5 X 10(5) CFU/ml. No cross-reactions were noted when each of the GBS serotypes was reacted with antibodies of differing serotypes specificities. Type III GBS native antigen was detected at a concentration of 1 ng/ml. The sandwich enzyme assay is more sensitive than other methods currently in use for rapid detection of GBS and is serotype specific. This assay system should prove useful for the detection of GBS colonization during labor and for identification of neonates with invasive disease.

Nanosecond response ''gasket-type'' magnetic loop current monitor for relativistic electron beam current measurements.

A fast response magnetic loop current monitor has been developed to measure relativistic electron beam return currents. The monitor has a rise time of about a nanosecond and a high degree of symmetry with moderate sensitivity, variable from about 1 to 10 V/kA. This simple monitor, with a thickness of 0.254 mm or less, is thin enough to be placed between segments of return current path in the diode or drift tube regions, is insensitive to flashover, beam and plasma bombardment, and radiation effects, and measures net current, thus offering some advantages over conventional magnetic probes, since the main components are outside of the vacuum region. Design criteria, an equivalent circuit analysis, and typical calibration waveforms are presented. Experimental current measurements for a pinched electron beam diode configuration using both conventional magnetic probes and ''gasket-type''current monitors with the FX-75 relativistic electron beam accelerator are presented.