Search results for "Blood substitute"

Influence of the polymerization step alone on oxygen affinity and cooperativity during production of hyperpolymers from native hemoglobins with cross…

1994

The aim of this study was to find out how the polymerization per se changes oxygen affinity (P50) and cooperativity (n50) of various soluble huge hyperpolymers prepared from native hemoglobins by crosslinking. Increase of cooperativity would be expected considering natural hemoglobin networks. Those hyperpolymers with molecular weights of some 10(6) g/mol are candidates for artificial oxygen-carrying blood additives rather than volume substitutes. Human and bovine hemoglobin reacted with several crosslinkers (2,5-diisothiocyanatobenzenesulfonate (DIBS); 4,4'-diisothiocyanatostilbene-2, 2'-disulfonate (DIDS); 1,3-butadiene diepoxide (BUDE); glutaraldehyde (GDA)) in concentrated (case 1) and …

Hemoglobin loaded polymeric nanoparticles: preparation and characterizations.

2011

In the present work polymeric nanoparticles based on Poly (maleic anhydride-alt-butyl vinyl ether) 5% grafted with m-PEG (2000) and 95% grafted with 2-methoxyethanol (VAM41-PEG) were loaded with human hemoglobin (Hb) and characterized from a physicochemical point of view. The assessment of structural and functional features of the loaded Hb was performed and the effect of the introduction of different reducing agents as aimed at minimizing Hb oxidation during the nanoparticles formulation process, was also investigated. Nanoparticles possessing an average diameter of 138 ± 10 nm and physicochemical features suitable for this kind of application were successfully obtained. Although the oxida…

Molar masses and structure in solution of haemoglobin hyperpolymers--a common calibration of size exclusion chromatography of these artificial oxygen…

1997

We are developing artificial oxygen carriers for medical use, based on synthetic polymers--so-called hyperpolymers--obtained by cross-linking mammalian haemoglobins. One requirement with respect to the polymers is that they should not increase the oncotic pressure of blood remarkably--this can be realized by high molecular weights of the polymers with a narrow distribution. They may act as a oxygen transporting blood additive, and--in combination with a plasma expander--as a blood substitute. Another important and desired property of the artificial oxygen carrier is a low viscosity, which--first--is due to a high degree of uniformity of the polymer size (or molar mass) distribution and--sec…

A model of stepwise isovolaemic blood exchange in anaesthetised, spontaneously breathing rats to evaluate the oxygen transport efficiency of artifici…

2000

Our research pursues the production of hypo-oncotic artificial oxygen carriers, based on artificial covalently cross-linked hyperpolymeric mammalian haemoglobins. To evaluate their in vivo efficiency in oxygen delivery to the tissue we developed a small animal model of stepwise isovolaemic blood exchange in anaesthetised, spontaneously breathing rats. With the aid of a two-way respiratory micro valve for small animals the overall oxygen uptake by the tissue of the animal can be determined. Measurements of oxygen contents in arterial and mixed venous blood and of some further blood parameters together with known oxygen-binding characteristics of artificial and native oxygen carriers, permits…

Oxygen-carrying v. non-oxygen-carrying colloidal blood substitutes in schock

1982

Loss of more than 10-15 per cent of the circulating blood causes a corresponding fall in filling pressure and a marked reduction in minute volume. In order to combat a fall in the minute volume, catecholamines are liberated, the stimulating components of these cause a rise in vessel tone. In spite of the blood volume being reduced by blood loss, filling pressure and minute volume are restored by compensating mechanisms as long as the volume lost is not enough to exceed the autoregulative capacity. Even with a blood loss of 10-15 per cent, full compensation is not achieved without replenishing the blood volume unless the fluid lost from the vascular bed is less than I0 per cent of the total.…

A New Type of Artificial Oxygen Carrier: Soluble Hyperpolymeric Haemoglobin with Negligible Oncotic Pressure—Production of Thermally Stable Hyperpoly…

1992

Low Viscosity of Densely and Highly Polymerized Human Hemoglobin in Aqueous Solution — the Problem Of Stability

1989

In case of chronic and acute tissue oxygen deficit it is of advantage to have an artificial oxygen carrying blood substitute in order to support a least temporarily blood function. From a physico-chemical point of view an artificial oxygen carrying blood substitute must meet 4 main requirements at the desired concentration.