Computer Detection of Distortion in Arterial Pressure Signals

An application of the mathematical concept of curvature to the detection of distortion in arterial pressure signals is described. Curvature is defined and examples of digitally filtered pressure tracings show the relationship between curvature and the degree of damping. Even though curvature is also a function of the cardiovascular system producing the signal, the average sum of curvature can generally distinguish control signals from signals distorted by moderate amounts of blood or air in the catheter systems. Selected pressure signals with their associated sums of curvature show the properties and limitations of curvature for discriminating between the changes in the cardio-vascular system and distortion of pressure signals.     

Routine erythrocyte measurements in diagnosis of iron-deficiency anemia and thalassemia minor

A study was made of the routine electronic measurements of erythrocyte size and hemoglobin concentration in blood samples from 122 patients with decreased transferrin saturation and 66 patients with elevated levels of hemoglobin A2 or F. The medical histories of these patients were reviewed to identify 52 cases of uncomplicated iron-deficiency anemia and 39 cases of uncomplicated thalassemia minor. Four decision functions were compared for separating these two disorders. The functions evaluated were: D.F'. = MCV--[5 X Hb]-RBC; ratio MCV/RBC; ratio MCH/RBC, and RBC. The rules performed better in the uncomplicated cases than in the routine laboratory defined cases. Only minor differences in the performances of the various decision functions were observed. None was sufficiently accurate for final diagnosis, but they should have value in screening patients and in determining which additional test should be considered.     

Unvernetzte epoxid-amin-additionspolymere, 25. Oligoether-diamine als elastifizierende comonomere für lineare epoxid-amin-additionspolymere

N,N'-Dibenzyl-3,6-dioxaoctane-diamine-1,8 and three analogous secondary diamines (EDA) all of which have long chain aliphatic ether groups were prepared and reacted with diglycidylether of bisphenol-A (DGEBA) to give well defined linear epoxide-amine addition polymers. Due to the flexible spacer in the amine component, the glass transition temperatures (T_g) of DGEBA/EDA copolymers decrease to 9–23°C. Likewise T_g's of DGEBA/polyamine networks are significantly lowered by copolymerization with EDA (T_g = 25 –100°C). Such flexible copolymers may be used as strain free optical adhesives or as the soft component in polymer blends and interpenetrating networks. Thermodynamic and kinetic polyreaction parameters were measured by DSC. In excellent correspondence with experiments, data have been calculated using a refined reaction model. This includes both noncatalyzed and catalyzed parallel reactions. The latter ones are activated by NH···HO complexation resulting from growing amounts of HO groups in the addition product.     

Alpha-and beta-halomorphides: stereochemistry, analgesic potency, toxicity, and interaction with narcotic receptors in vitro

The configuration of the halogen on the C-ring of several alpha- and beta-halomorphides was determined by NMR. The analgesic potencies of these halomorphides and their interactions with narcotic receptors in a rat brain homogenate were measured, as was the toxicity of the alpha- and beta-chloromorphides. The halomorphides were examined as possible irreversible binders to the narcotic receptor.     

Surface modification of polyurethane by plasma-induced graft polymerization of poly(ethylene glycol) methacrylate

A new approach, plasma-induced graft polymerization of poly(ethylene glycol) methacrylate (PEGMA), was used to introduce PEG graft chains with hydroxyl end groups onto a polyurethane (Tecoflex) surface. After argon plasma treatment and subsequent exposure to air, graft polymerization onto Tecoflex films was allowed to proceed in deaerated aqueous solutions of PEGMA at 60°C. The virgin, plasma-treated, and grafted films were characterized comparatively by means of attenuated total reflection infrared spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy, measurement of contact angle, and protein adsorption. The Tecoflex film undergoes etching during argon plasma treatment, surface oxidation when exposed to air after plasma treatment, and surface restructuring in response to environment upon storage in air. The plasma-induced graft polymerization of PEGMA proved to be successful in introducing PEG graft chains with reactive hydroxyl end groups onto the surface. Grafted films with different surface grafting density of PEG were prepared. Grafted films with higher PEG content exhibit higher hydrophilicity, smoother topography, and lower fibrinogen adsorption. The hydroxyl end groups built onto the surface offer further possibilities of improving its biocompatibility by immobilizing bioactive molecules. © 1996 John Wiley & Sons, Inc.     

Extracellular Stimulation of a Cell Having a Non-Uniform Membrane

The response to extracellular simulation of a cell having a non-uniform membrane consisting of a low resistance patch in an otherwise high resistance membrane is examined. The presence of the patch is shown to cause a shift in the isopotential value of the intracellular medium towards the value of potential just outside the patch. The quantitative dependence of this shift upon the electrical parameters of the system is examined; the effect of such a shift upon the distribution of induced transmembrane potentials is discussed; and the case of a cell with multiple low resistance patches is treated.     

High-molecular weight diepoxide-dicarboxylic acid addition polymers

Summary The addition polymerization of 2,2-bis[4-(2,3-epoxypropoxy)phenyl] propane (DGEBA) and dicarboxylic acid results in high molecular weight addition polymers (M_n 8000–13000). Their molecular weight distribution is rather broad (M_w/M_n=11,6) due to side reactions such as transesterification and formation of ether linkages. Due to the incorporation of the aliphatic dicarboxylic acid moieties in the polymer backbone, the addition polymers show relatively low glass transition temperatures ranging from 26 to 45 °C.