Generation of LexA enhancer-trap lines in Drosophila by an international scholastic network

Conditional gene regulation in Drosophila through binary expression systems like the LexA-LexAop system provides a superb tool for investigating gene and tissue function. To increase the availability of defined LexA enhancer trap insertions, we present molecular, genetic, and tissue expression studies of 301 novel Stan-X LexA enhancer traps derived from mobilization of the index SX4 line. This includes insertions into distinct loci on the X, II, and III chromosomes that were not previously associated with enhancer traps or targeted LexA constructs, an insertion into ptc, and seventeen insertions into natural transposons. A subset of enhancer traps was expressed in CNS neurons known to produce and secrete insulin, an essential regulator of growth, development, and metabolism. Fly lines described here were generated and characterized through studies by students and teachers in an international network of genetics classes at public, independent high schools, and universities serving a diversity of students, including those underrepresented in science. Thus, a unique partnership between secondary schools and university-based programs has produced and characterized novel resources in Drosophila, establishing instructional paradigms devoted to unscripted experimental science.

Nerve injury after primary total knee arthroplasty

There is controversy about the incidence of and predisposing factors to the development of peripheral nerve palsy after total knee arthroplasty (TKA). In this study, 19 patients with a documented neurologic complication were identified after a retrospective review of 1,476 primary TKAs performed between January 1970 and December 1998 at the New York Presbyterian Hospital at Columbia University, for an overall incidence of 1.3%. Contrary to previously published data, valgus deformity, flexion contracture, the use of postoperative epidural anesthesia, the prolonged use of pneumatic tourniquets, and preexisting neuropathy were not associated with the development of peripheral neuropathy after TKA based on our data. A larger percentage of rheumatoid knees experienced a neurologic injury than was expected, however. No other significant risk factors for peripheral neuropathy after TKA were identified based on data from our patients. Immediately after discovery of the nerve palsy, conservative treatment was employed for each of our patients. All patients showed at least a partial recovery at the end of follow-up, with most experiencing a complete recovery from symptoms.

Tuberculous arthritis in children. Diagnosis by needle biopsy of the synovium

In two children ages 8 months and 4 years, tuberculous synovitis of the knee was suggested by pathologic examination of synovial tissue obtained through needle biopsy. Culture of the biopsy material was positive for Mycobacterium tuberculosis in one case. In this child, the tuberculin test was negative, in the absence of anergy, at the time the child was first evaluated, and the primary lung lesion was not identified by the radiologist. Tuberculous synovitis has not previously been recognized as part of primary tuberculosis during the early weeks when the tuberculin skin test may be negative. Magnetic resonance imaging (MRI) is a sensitive modality for demonstrating joint fluid, synovial hypertrophy, and associated osteomyelitis, if present. With the increasing frequency of cases of tuberculosis in the population, greater awareness of the risk of tuberculous arthritis in childhood is important in order to recognize this unusual presentation. If negative early on, the tuberculin skin test should be repeated after 6 weeks of arthritis. A needle biopsy of the synovium is helpful and appropriate in all children with monoarticular arthritis who have a positive tuberculin skin test.

The flipped meniscus sign

Meniscal fragments may be difficult to detect on magnetic resonance (MR) imaging and yet are clinically significant. This paper describes and illustrates the MR appearance of an easily overlooked meniscal fragment. Ten knees, each appearing to show an abnormally large anterior meniscal horn (8 mm or more in height) were prospectively identified on MR images. In each case demonstrable large tears of the ipsilateral posterior horns were present (same meniscus as had large anterior horns). The lateral meniscus was involved in nine cases and the medial in one. Two of the ten patients imaged had surgically proven bucket-handle meniscal tears as well as meniscal fragments overlying the ipsilateral anterior horn. In one case previous MR imaging at our institution had demonstrated the affected anterior horn to be of normal caliber. The striking MR appearance of an abnormally enlarged anterior meniscal horn in association with a tear of the ipsilateral posterior horn suggests the presence of a meniscal fragment or of a posteriorly detached bucket-handle tear of the posterior horn of the meniscus.

MR imaging of displaced bucket-handle tear of the medial meniscus

A bucket-handle tear of the meniscus is a vertical or oblique tear with longitudinal extension toward the anterior horn in which the inner fragment is frequently displaced toward the intercondylar notch with resultant mechanical locking of the knee joint. A precise MR diagnosis requires identification of the centrally displaced fragment because the peripheral nondisplaced component may have only a subtle truncated or foreshortened appearance that may escape detection. Eighteen consecutive cases of displaced bucket-handle tears of the medial meniscus diagnosed by MR had a characteristic low-signal band extending across the joint and projecting over the medial tibial eminence. The posterior portion was parallel and beneath the posterior cruciate ligament on both sagittal and coronal images. Arthroscopy confirmed the presence and location of the displaced fragment in all 18 cases. Awareness of this characteristic MR finding may increase the sensitivity of MR imaging in the diagnosis of bucket-handle tears of the medial meniscus.

Postamputation neuromas and other symptomatic stump abnormalities: detection with CT

One of the potentially troublesome sequelae of limb amputations is the development of stump neuromas at the severed ends of major nerves. The ability to define them and to distinguish them from other causes of stump pain is of considerable clinical significance. Computed tomography was performed on ten lower limb amputees with stump pain. Five patients had neuromas that were manifest as focal or generalized alteration in the caliber, size, or contour of the nerve trunk in the affected stump. The remaining five patients each had an abnormality detected; these abnormalities included heterotopic bone formation, popliteal artery aneurysm, lipoma, scar tissue, and abscess in the contralateral limb.

Potentiometric Titration Methods for the Determination of Sodium Chloride in Certifiable Water-Soluble Colors: Collaborative Study

In a collaborative study, 7 laboratories successfully analyzed 8 different samples, in duplicate, by a manual potentiometric titration method. These same samples were used by 7 different laboratories in a concurrent collaborative study of the automated potentiometric titration method. The samples are dissolved in water and acidified, and soluble chloride is determined by titration with silver nitrate to the potentiometric end point. The methods are applicable to all water-soluble certifiable colors except D&C Red No. 19, at levels >0.03% sodium chloride, although there is a positive error at very low levels for the automated titration. In halogenated fluoresceins, any iodide or bromide is determined as sodium chloride, but the maximum amount normally present is equivalent to <0.2% sodium chloride. The sodium chloride content of the collaborative samples ranged from 0.04 to 18.2% for the manual method, and from 0.11 to 18.1% for the automated method. In general, except at very low sodium chloride levels, the precision of the automated method was good, although not as high as that for the manual method; single determination coefficients of variation ranged from 1.5 to 13.5% for the former, and from 1.2 to 2.7% for the latter. Recovery of 0.45% added sodium chloride ranged from 62 to 96%, and for 4.5% added sodium chloride it varied from 94 to 99% by the automated method. Recoveries ranged from 96 to 104% for 0,45% added sodium chloride and from 98 to 102% for 4.5% added sodium chloride by the manual method. The coefficient of correlation of the sample means for the manual and the automated methods was 0.9999%. The methods have been adopted as official first action.

An operative repair of acromioclavicular separation

Sixteen patients underwent an open reduction for complete acromioclavicular separation with a loop of woven Dacron arterial graft. This technique of internal fixation permits an early range of shoulder motion and eliminates the need for a second procedure to remove wire or pins. Experience in vascular reconstruction suggests that fibroblastic ingrowth might occur to substitute for the disrupted ligament complex. All but two of the 16 patients showed excellent results: full restoration of shoulder function, satisfactory cosmesis, and complete relief of pain. One required reoperation for an improperly placed loop, and one had definite over-reduction of the clavicle on the acromion but remained asymptomatic. In several, X-rays showed evidence of pressure resorption and periosteal new-bone formation along the clavicle at the site of the loop, but no loss of fixation. This approach was used successfully in acute trauma and as late as one year following injury.