We have studied the ability of histidine-rich glycoprotein (HRG) to neutralize the anticoagulant activity of heparin in plasma and in a purified component clotting assay. Addition of HRG to plasma or to the purified component assay did not neutralize the anticoagulant activity of heparin unless micromolar concentrations of zinc were present. Higher zinc concentrations were required for citrated than for heparinized plasmas due to competition of citrate with HRG for zinc binding. Zinc concentrations as low as 1.25 M revealed HRG to be a powerful competitor of antithrombin for heparin in the purified component assays. HRG binding of heparin also was shown by affinity chromatography of HRG from immobilized heparin in the presence and absence of zinc. In the absence of zinc, HRG was eluted by 0.1 M NaCl, but, in the presence of zinc, elution of HRG required 1.0 M NaCl. Investigation of other divalent cations (copper and magnesium) indicated that augmentation of heparin binding by HRG in the presence of antithrombin was restricted to zinc. The HRG⅐Zn complex effectively competes with antithrombin for heparin, which restricts the availability of heparin to bind antithrombin and allows thrombin-mediated fibrinogenesis to proceed unimpeded. This could be initiated by zinc released from activated platelets.
We report on a case of lingual tonsillar hyperplasia contributing to refractory obstructive sleep apnea in a 5-year-old patient. We describe a novel technique utilizing suspension laryngoscopy and a laryngeal angled shaver to remove obstructive lingual tonsillar tissue. We review the available techniques for lingual tonsillectomy and propose theoretical advantages to the novel approach.
Objective: To describe the mechanical rationale and clinical application of prototype right-angle reduction forceps.Methods: A pair of prototype right-angle reduction forceps was designed and manufactured specifically to improve the consistency and ease of fracture reduction. It was used to reduce mandible fractures of the mandible body, parasymphysis, and symphysis in 4 patients. The fractures ranged from minimally displaced to comminuted and displaced fractures.
Results:The pilot monocortical holes used for insertion of the right-angle reduction forceps into the mandible were easier to drill than the old method of drilling angled holes for standard reduction forceps. The older method required constant guesswork as to the correct angle of the hole relative to the tines of the curved reduction forceps. The right-angle reduction (REPRINTED) ARCH FACIAL PLAST SURG/ VOL 9
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