Receptors for C3b on the neutrophil surface associate with the cytoskeleton-containing cell residue subsequent to cell lysis with non-ionic detergent. Cytoskeletal-CR1 interactions.

Radioiodinated Fab' and F(ab')2 fragments were prepared from 57F monoclonal antibody which is specific for the C3b receptor (CR1) on human cells. We find that both Fab' and F(ab')2 fragments bind to CR1 on human neutrophils and then dissociate, at 0 degree C, with half-lives of 172 and 35 min, respectively. In addition to binding to cell surface CR1, both antibody fragments bind specifically to the isolated non-ionic detergent-insoluble cellular residue (NDIR) which remains after cell lysis and solubilization in Triton X-100. We also find that Fab' and F(ab')2 antibody fragments remain associated with the NDIR after the radiolabeled antibody fragments are allowed to bind to cell surface CR1, the unbound fragments removed, and the cells subsequently lysed in non-ionic detergent. Because the cytoskeletal matrix (together with the cell nucleus) makes up a substantial portion of the NDIR, these results suggest that some fraction of cell surface CR1 may be associated in vivo with the cytoskeletal matrix. However, post-lysis association of cell surface-CR1-antibody fragment complexes to the NDIR occurs. Examination of the binding kinetics of this interaction reveals that less than 10% of cell surface CR1 exists bound to the NDIR prior to cell lysis. While the nature of post-cell lysis association of CR1 with the NDIR is unknown, several modulating effects are noted. For example, binding of bivalent cross-linking agents to CR1 on cells followed by a 37 degrees C incubation is known to induce internalization of cell surface CR1. We find that binding of F(ab')2 antibody fragments under these conditions causes a 50% decrease in association of this 57F fragment to the NDIR. Pretreatment of the cells at 37 degrees C with the chemotactic peptide N-formyl-methionyl-leucylphenylalanine similarly caused a 50% decrease of (Fab'-labeled) CR1 association with the NDIR cell fraction. These results support the hypothesis that chemotactic peptide serves to enhance CR1-mediated adherence to C3b-bearing targets by increasing the density of CR1 on the cell surface rather than by inducing cytoskeletal-dependent, detergent-stable, CR1 redistribution on the cell surface.

Mycotic aneurysm in a digital artery: case report and literature review.

A mycotic aneurysm of the common digital artery at its junction with the palmar arch, extending into the ulnar proper digital artery of the index finger, is reported in a patient with endocarditis. A review of the English-language literature revealed no case of mycotic aneurysm in a digital artery. Diagnosis of the aneurysm was established noninvasively by ultrasound. Because this patient lacked a radial proper digital artery to the finger, the aneurysm was managed by excision and revascularization with a bypass graft from the long finger. Postoperative circulatory monitoring was facilitated by a pulse oximeter.

Arteriovenous reversal for limb salvage in unreconstructible upper extremity arterial occlusive disease.

PURPOSE: Peripheral vascular disease of the upper extremity as a result of atherosclerotic disease or systemic vascular disorders presents a difficult management problem to the vascular surgeon. When extensive distal disease is present bypass procedures with standard arterial reconstruction techniques may not be possible. The use of retrograde perfusion to deliver oxygenated blood to the capillary bed by means of a normal venous system is not new. Flow reversal has been attempted in the myocardial, cerebral, and distal extremity circulations. Arteriovenous reversal (AVR) has been described for limb salvage in patients with upper extremity ischemia, with variable results. METHODS: We performed six AVR procedures on five patients with diffuse distal arterial disease and limb-threatening upper extremity ischemia. Two patients had insulin-dependent diabetes, one had systemic lupus erythematosus (two extremities), one had rheumatoid arthritis with vasculitis, and the remaining patient had CRST (calcinosis, Raynaud's disease, sclerodactyly, telangiectasia) syndrome. The two patients with diabetes had systemic manifestations of atherosclerotic vascular disease and lower extremity ischemia; the remaining three patients had no evidence of atherosclerosis. In all patients the AVR was performed at the most distal site of nondiseased artery. RESULTS: Limb salvage was obtained in all cases; one patient had a healed minor digital amputation, and another patient had a healed major amputation. Clinical improvement with resolution of pain was achieved in five of six cases. The remaining patient had a significant diabetic neuropathy that was believed to contribute to her persistent pain. CONCLUSIONS: In patients with severe upper extremity ischemia not amenable to standard revascularization techniques, AVR should be considered to provide limb salvage and maximize hand function.

The figure-of-eight splint for proximal interphalangeal joint volar plate injuries.

Volar plate disruption of the proximal interphalangeal (PIP) joint is a common hand injury. Management of this injury must provide stability and motion to avoid disabling instability or stiffness. In this study, 40 patients with closed PIP joint volar plate injuries were treated with the figure-of-eight splint, a custom made, thermoplastic splint that allows protected joint motion. At two-year follow-up, 95% of these patients experienced good or excellent results. The figure-of-eight splint offers a simple and effective method of treatment for volar plate injuries of the PIP joint.