The binding and processing of monoclonal human IgG1 by cells of a human macrophage-like cell line (U937)

The goal of these experiments was to assess the relationship between the binding and processing of IgG by Fc-receptor-bearing cells. Cells of the U937 human macrophage-like cell line were incubated with 125I- labeled monomers, dimers, oligomers (composed of 2-4 IgG1 subunits), and HP (heavy polymers composed of 5 or more subunits per polymer) of monoclonal human IgG1 in vitro. Binding was assessed by spinning cells through a layer of phthalate oils. Internalization of IgG1 was assessed by quantitating residual binding to cells after surface-bound IgG was removed by a brief treatment with a solution containing 0.25 M acetic acid and 0.5 M sodium chloride. Catabolism was assessed by measuring the release of radioactive fragments of IgG1, which were not precipitated by 10% trichloroacetic acid. Unstimulated U937 bound about 10,000 molecules per cell of IgG1 monomer, with an equilibrium binding constant (Ka) of 5 X 10(8) M-1. After stimulation with a conditioned medium in vitro, binding per cell was increased 3-7--fold, and the Ka was decreased 2-4--fold. Both unstimulated and stimulated cells internalized and catabolized labeled IgG1 HP, but stimulated cells internalized and digested much more IgG1 HP per cell than unstimulated cells. Both monomers and dimers of IgG1 were internalized and degraded very slowly by stimulated cells, even though both preparations readily bound to cells. In contrast, oligomers and (to an even greater extent) IgG1 HP were internalized and degraded much more rapidly. Internalization of IgG1 HP was markedly inhibited by incubation at 4 degrees C, but not by incubation with a variety of metabolic inhibitors. Catabolism was inhibited by chloroquine and monensin (inhibitors of lysosomal acidification) and by cytochalasin (an inhibitor of microfilament polymerization). Binding to the surface of cells was not markedly inhibited by any agent tested. The capacity of cells to bind labeled IgG1 was markedly reduced by prior incubation in the presence of unlabeled IgG1. This reduction was in part due to the steric blockade of receptors caused by the avid, but reversible, binding of IgG1. In addition, IgG1 oligomers or HP (but not IgG1 monomers or dimers) also caused an irreversible reduction in the number of Fc receptors by a process analogous to receptor down-regulation, as observed in other receptor--ligand systems.     

Cavus deformity of the foot after fracture of the tibial shaft.

Twenty-three cases of claw foot with limited talocrural and subtalar mobility were the result of muscle contracture of the leg after tibial-shaft fracture. A roentgenographic study including arteriography was performed. It was concluded that the typical short cavus foot is due to fibrous contracture of the muscles in the deep posterior compartment caused by vascular damage, swelling in the deep posterior compartment, or severe muscle laceration. On physical examination the distance between the lateral malleolus and the Achilles tendon was shortened in comparison with the sound side in all cases. This was found to be caused by dorsiflexion in the talocrural joint coincident with adduction in the mid-tarsal joint. The angulation of the foot forced the patients to rotate the leg outward in order to get the feet in parallel position for walking. This deformity could be misinterpreted as an inward malrotation of the tibial fracture. In severe cases a derotating three-dimensional wedge osteotomy of the distal part of the tibia was performed with promising results.     

Pulmonary Microembolism During Intramedullary Orthopaedic Trauma

Patienten, die für prothetische Hüftoperationen nach der Methode nach Charnley vorgesehen waren, erhielten am Tag vor dem Eingriff ⁵¹Cr-markierte Thrombozyten und ¹²⁵I-markiertes Fibrinogen. Wahrend des chirurgischen Eingriffes wurden beide Arten der Radioaktivät über der rechten Lunge extern registriert. Eine vorübergehende Anhäufung der ⁵¹Cr-Aktivität über der Lunge wurde während des Ausraumens des Knochenmarks aus dem Femur und nach dem Einsetzen der Femurstammprothese beo-bachtet. Wahrend dieser zweiten Phase wurde auch eine vorubergehende Haufung der ¹²⁵I-Radio-aktivitat registriert. Nach dem Einsetzen der Femurprothese fiel die arterielle Sauerstoffspannung (Pa_O2) significant ab. Der Korrelationskoeffizient war—0,97 zwischen dem vermehrten Auftreten der ¹²⁵I-Radioaktivität in der Lunge und der nach dem Einsetzen der Femurprothese auftretenden Pa_O2-Reduktion. Diese Resultate könnten als Anzeichen von Mikroembolis-ationen in die Lunge in diesem Operationsstadium interpretiert werden bei gleichzeitiger pulmonaler Dysfunktion.     

Spinal pseudarthrosis with paraplegia in ankylosing spondylitis

Summary Destructive lesions of vertebral bodies in ankylosing spondylitis (AS) have for a long time been regarded as inflammatory changes, sometimes of tuberculous etiology. However, observations during recent years have established that these destructions in fact are non-unions after fractures. A case of spinal pseudarthrosis with paraplegia in a patient with advanced AS is presented. After combined anterior and posterior decompression as well as fusion using plate fixation, the neurological symptoms regressed completely and early mobilization of the patient was possible.

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Zusammenfassung Wirbelkörperdestruktionen bei ankylosierender Spondylitis (AS) sind lange als Folgezustände — oft tuberkulöser — Entzündung aufgefaßt worden. Beobachtungen der letzten Jahre haben jedoch klargestellt, daß es sich hierbei um Pseudarthrosen nach Wirbelfrakturen handelt. Eine spinale Pseudarthrose mit Querschnittslähmung bei einem Patienten mit AS wird beschrieben. Nach kombinierter vorderer und hinterer Dekompression und Spondylodese unter Verwendung einer Plattenfixation trat schneller Rückgang der neurologischen Symptome ein, und der Patient konnte frühzeitig remobilisiert werden.

     

The significance of radiolucent zones surrounding pedicle screws. Definition of screw loosening in spinal instrumentation

We examined the radiographs from a prospective clinical study of fixation by pedicle screws and those from an experimental study in a sheep model. In the clinical study, instruments were removed from 21 patients after implantation for 11 to 16 months and the extraction torques of the screws were recorded. A structured protocol was used for the radiological examinations. In the experimental study, loaded pedicle screw instrumentations were implanted in the sheep for six or 12 weeks. After radiological examination the pull-out resistance and the histological characteristics were studied. In the clinical study, all screws with radiolucent zones had a significantly reduced mean extraction torque compared with screws without radiolucent zones (16 +/- 10 Ncm v 403 +/- 220 Ncm; p < 0.0001). In the experimental study the mean maximum pull-out resistance for the screws with radiolucent zones was significantly lower than for those with no radiolucency (243 +/- 156 N v2214 +/- 578 N; p = 0.0006) and the mean bone-to-screw contact was reduced for screws with zones compared with those without zones (8 +/- 9% v 55 +/- 29%; p = 0.0002). Our findings showed that all screws with radiolucent zones had low extraction torques or low pull-out resistance. A radiolucent zone is a good indicator of loosening of a pedicle screw.     

Airway intervention in adult supraglottitis

Background The timing of aggressive airway intervention in adult epiglottitis is controversial. Aims To correlate Friedman’s staging of epiglottitis on admission with the airway interventions undertaken. Methods A retrospective study of 23 adult patients, mean age 51 years (range 29–81 years), who had been admitted with acute supraglottitis between March 1988 and December 2000 was undertaken. Results Three patients (13%) had airway interventions; two with tracheostomy and one with tracheal intubation. All were Friedman stage III and had rapid symptom progression during the 24 hours prior to admission. Three other stage III patients with symptom progression longer than 24 hours and all the remaining patients (stage II or less) were managed with observation and intravenous therapy. Conclusions Friedman originally advocated airway intervention in any patient stage II or worse, but this intubation threshold should probably be lowered to those patients with rapid-onset stage III (moderate respiratory distress, stridor, respiratory rate >30 per minute, pCO₂ >45mmHg) disease.     

Cauda equina syndrome as a postoperative complication in five patients operated for lumbar disc herniation

STUDY DESIGN: A retrospective analysis of records and radiographs in five patients who developed acute cauda equina syndrome after surgery for lumbar disc herniation. OBJECTIVES: To postulate as a possible pathophysiologic mechanism the venous congestion caused by preexisting spinal stenosis and to present a management plan: extended decompression within 48 hours. SUMMARY OF BACKGROUND DATA: Cauda equina syndrome is reported as a sequela in 0.2%-1% of the surgeries for lumbar disc herniation. There is, however, no consensus on the possible pathophysiologic mechanism to the complication or to its management. METHODS: Preoperative investigations consisted of magnetic resonance imaging, or myelography and computed tomography. There was a good correlation between clinical appearance and radiographic findings in all patients. When the complication became apparent in four of the patients, they were investigated with magnetic resonance imaging and reoperated on within 48 hours with wide decompressions. RESULTS: The index operation was reported uneventful in all patients. Postoperative magnetic resonance imaging did not show the cause of the cauda equina syndrome, nor could this be established at the reoperation. Before surgery, all five patients had preexisting narrowing of the spinal canal. In no case was the lumbosacral disc the index level. Two patients recovered fully, whereas the other three experienced varying degrees of residual symptoms. There was no correlation between the end result and the delay until secondary decompression. CONCLUSION: Relative spinal stenosis may contribute to the development of cauda equina syndrome after surgery for lumbar disc herniation. A venous congestion can be triggered by postoperative edema, leading to nerve root ischemia. The treatment of choice seems to be extended decompression within 48 hours.