Complications of transesophageal echocardiography in the ED.

The complication rate of transesophageal echocardiography (TEE) performed in clinical settings outside the emergency department (ED) has been reported to be 1% to 3%. The rate of complications of performing TEE in the ED has not been established. The purpose of this study was to determine the rate of complications associated TEE with carried out on ED patients, and to investigate parameters that might predict complications. A retrospective chart review was carried out on consecutive ED patients undergoing TEE at a major referral center. Complications were abstracted. Parameters to predict complications were assessed, including age, gender, vital signs, pulse oximetry values, serum bicarbonate level, and hematocrit level. A total of 142 patients underwent TEE in the ED during the study period; 88 of these were trauma patients. There were 18 (12.6%) complications: death (1), respiratory insufficiency/failure (7), hypotension (3), emesis (4), agitation (2), and cardiac dysrhythmia (1). None of the tested variables predicted a complication. TEE carried out in the ED has a higher complication rate than has been reported in other clinical settings.

Heterogeneity of human bone.

Matched samples of bone from the lumbar spine and tibia were obtained at autopsy from three adult males who had no known evidence of metabolic bone disease at the time of their demise. The soluble noncollagenous bone proteins were quantitatively extracted from these samples and assayed for the relative content of two bone-associated proteins, osteocalcin and osteonectin. When compared to trabecular bone, cortical bone had higher levels of osteocalcin and much lower levels of osteonectin. When concentration is expressed per gram of dried bone, the osteocalcin excess in cortical bone ranged from 30- to 32-fold, and the osteonectin excess in trabecular bone ranged from 21- to 47-fold. These differences were significant (P less than 0.01) using analysis of variance. We conclude that the human skeleton is not homogeneous with regard to these biochemical markers and that cortical and trabecular bone are biochemically quite distinct. This implies that these two types of bone may be subject to distinct regulatory mechanisms and that global assessments of skeletal function and bone quality based upon soluble markers should be applied with caution. The data also imply that a differential assessment of skeletal performance may be possible using biochemical serum markers.

The interaction of bone Gla protein (osteocalcin) with phospholipid vesicles.

The binding interaction of bone Gla protein (BGP), or osteocalcin, to phospholipid vesicles in the presence of calcium has been investigated. Two separate indirect methodologies involving displacement of pyrene-modified Factor Va bound to phospholipid vesicles, and competition with several coagulation proteins in a prothrombin activation assay were performed. Titration of BGP into a cuvette containing phospholipid vesicles (75:25, L-alpha-phosphatidylcholine/L-alpha-phosphatidylserine (PCPS] saturated with pyrene-modified Factor Va resulted in a systematic decrease in steady-state anisotropy, suggesting competition for membrane binding sites with pyrene-modified Factor Va. BGP was also found to inhibit thrombin generation in the prothrombin activation assay. Approximately 50% inhibition was observed at 3 microM BGP under phospholipid-limiting (0.5 microM PCPS) concentrations. No inhibition was observed under phospholipid excess (30 microM PCPS) concentrations. Direct measurement of phospholipid binding was measured using equilibrium gel filtration. Elution profiles using fixed lipid (3.4 mumol of PCPS) and varying BGP concentrations (1-17 microM) in the presence of 3 mM CaCl2 showed a BGP-phospholipid association. Quantitation of determined isotherm yielded a dissociation constant of 6 +/- 1 microM with a stoichiometry of 102 +/- 9 BGP molecules/vesicle at saturation (35 PCPS lipids/BGP) in the presence of 3 mM CaCl2. These results support the hypothesis that protein gamma-carboxylation events are coincident with membrane binding potential.