ABSTRACT
The quantity of protein and carbohydrate comprising the matrix of calcium oxalate monohydrate (COM) renal stones was found to decrease with distance from the surface of the stone. The average organic concentration of stones 3 to 30 mm in diameter ranged from 5.7% at the surface to 2.7% at the core. This concentration gradient suggests matrix involvement in a "growth front" on stone surfaces with migration of organic material from the "older" interior. The matrix distribution was not readily correlated with density variations or with the presence of hydroxyapatite or calcium oxalate dihydrate. Surface matrix concentrations were greater than amounts predicted by physical adsorption. Electron microscopy confirmed the presence of the organic-rich surface layer and also suggested that increase in stone size occurs predominantly by crystal growth with microcrystal aggregates as growth centers.
Subject(s)
Calcium Oxalate/analysis , Carbohydrates/analysis , Kidney Calculi/metabolism , Proteins/analysis , Amino Acids/analysis , Humans , Kidney Calculi/pathology , Minerals/analysisABSTRACT
The analysis of the bonding interface between hip prostheses and bone after functional use in animals was carried out. Scanning electron microscopy (SEM) with energy dispersive analysis (EDX), and Auger electron spectroscopy were used to evaluate the bonding interface. Various methods of postsacrifice sample preparation were used to evaluate the effect of such different methods on the analysis of the bonding interface. Comparison of the results with several rat tibia implant experiments is also presented.
Subject(s)
Glass , Joint Prosthesis , Aluminum , Animals , Biocompatible Materials , Bone and Bones/anatomy & histology , Chlorides/metabolism , Evaluation Studies as Topic , Femur Head , Haplorhini , Hip , Macaca fascicularis , Microscopy, Electron, Scanning , Rats , Sheep , Surface PropertiesABSTRACT
As part of a new effort to develop an implantable drug infusion/pacing system to treat atrial fibrillation, this study examined the effects of rapid intracardiac procainamide infusion in humans with pacing-induced atrial fibrillation. Twenty patients with atrial fibrillation for > 5 minutes during an EP study received 500 mg of procainamide either via a peripheral venous infusion (n = 5) or directly in the right atrium (n = 15). Peak coronary sinus and femoral vein procainamide blood levels (mean +/- SEM) during 10, 5, and 3.3 minute central infusions were 17.0 +/- 4.1, 25.1 +/- 4.5, 45.6 +/- 5.1 and 11.3 +/- 3.2, 17.1 +/- 6.4, 18.7 +/- 5.0, respectively. In contrast, peak coronary sinus and femoral procainamide levels following the 5 minute intravenous infusion were 17.7 +/- 5.1 and 9.3 +/- 2.1. Changes in QT, QTc, QRS, and RI intervals were similar at each infusion rate. Systolic blood pressures (BP) decreased more with higher procainamide infusion rates but similar when comparing intravenous versus central drug administration at the same rate. The mean +/- SEM decreases in blood pressure with the 10, 5, and 3.3 min procainamide infusions were 12f5, 20f11, and 39f14, respectively. Conversion to sinus rhythm was not a primary endpoint given the often transient nature of acute atrial fibrillation in this setting. We conclude that significantly higher femoral vein and coronary sinus procainamide levels can be achieved by central rather than peripheral drug infusion. These data support that concept that rapid central infusion of anti-arrhythmic therapy can result in high intracardiac levels of antifibrillatory agents for the treatment of paroxysmal atrial fibrillation.