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Biomedical subjects

H Klinkmann

Publications and source records attributed to H Klinkmann.

At least 73 records · Page 4Linked to original sources

A newly developed LDL-binding material.

Results of in vitro and ex vivo experiments with a newly developed LDL-binding material are presented. This material consists of macroporous bead cellulose which is capable to bind selectively LDL. LDL-cholesterol is considerably decreased after contacts of plasma or serum samples with this bead cellulose. On the other hand high density lipoproteins (HDL) and other plasma components (proteins, enzymes, electrolytes, and metabolic substances) remained high or unchanged. Triglycerides (TG)--transported by very low density lipoproteins--are also bound up to a certain degree. 1 g of the adsorbent wet mass binds at least 20 mg cholesterol. The capacity suffices to decrease two- to threefold increased cholesterol and LDL plasma levels to the low normal range following passage of the sevenfold plasma volume' through two the three LDL adsorbent columns (results of perfusion experiments). In vitro and dog experiments revealed only slight drops of the hemolytic capacities of the classic complement pathway and moderate decreases of the alternative one. But no detectable side effects were noticed in the dog experiments.

Adsorption↗

[Clinical and morphologic factors for assessment of risk of progression of chronic glomerulonephritis].

In 182 patients suffering from bioptical-proved and functional adapted chronic glomerulonephritis the relation between clinical course, morphological type and progression of disease has been evaluated. The presented results show a significant relation between the clinical course of chronic glomerulonephritis and the progression trend of this disease. The early finding of sclerotic changes may follow a benign course of the disease.

Adult↗

[Precision of data from models of sodium kinetics in hemodialysis].

The 1-pool-model of sodium kinetics during hemodialysis is based upon the assumption of an immediate compensation of osmotic shifts. This assumption is not supported by measurements of plasma sodium, total protein concentration and colloid osmotic pressure kinetics. When a high dialysate sodium concentration is applied, an inflow of sodium into the plasma space occurs, which results in an osmotic suction and thus a plasma dilution. These conditions can be represented by a 2-pool-model taking into consideration capillary filtration. The results indicate that following the first treatment period the sodium kinetics are sufficiently explained by a 1-pool-model with the total body water as distribution volume. Both the plasma sodium concentration and the eliminated sodium at the end of a hemodialysis treatment can be described to an acceptable level by the 1-pool-model. The input of the measured in-vivo sodium dialysance value (or alternatively the urea clearance) is necessary.

Blood Proteins↗

Relationship between design and control of artificial heart for protection of the right/left balance.

Right/left matching in the total artificial heart (TAH) is essential to prevent fatal volume displacement into the pulmonary circuit. Measurements were made with three different sized Rostock pneumatic artificial ventricles incorporated in the Donovan mock circulatory system together with the heart driver AKT 86. First for each ventricle we determined the dependence of the maximum effective stroke volume on the systolic driving pressure and the afterload. The right ventricle (RV) is about 10% more effective than the left ventricle (LV). Control of the TAH permits different or equal frequencies for the RV and LV. For control with equal frequencies and full-to-empty regimen of one ventricle (RV-Master or LV-Master) the ratio of designed stroke volumes between RV and LV is important. This follows from the smaller efficiency of the LV and the left-to-left shunt. Otherwise a control mode with different heart rates must be used.

Heart, Artificial↗

[Current status of the use of the artificial heart and ventricular assist systems].

The state of the technical development of the mechanical assist systems and the artificial heart, respectively, guarantees a sufficient support of the circulatory system up to the improvement of the own heart function or to the possible heart transplantation. There is the necessity for the temporarily limited support of the heart, but also for the long-term one. Independent of the underlying etiology in acute conditions of cardiac failure in many cases the external supporting system may be sufficiently helpful. The antithrombotic therapy and the prophylaxis of infections demands particular carefulness. There is still no representable release for the long-term use of the hitherto available cardiovascular supporting systems. The question is controversial, whether then an experiment on patients or an already accepted therapeutic intervention is still taken into consideration. Essential prerequisites for the long-term use would be a full implantability of the systems in transcutaneous energy transmission, a further biologization of the blood-contacting materials, a clarification of the immune phenomena, a possibly automatic mode of action adapted to the need as well as a reliable strategy of antithrombotic therapy. The increased risk of infection should be taken into consideration.

Animals↗

[Pathophysiologico-clinical aspects of so-called compensatory hypertrophy of the kidney].

In a survey is reported on the present level of knowledge of the nephronal functional and structural adaptation in the so-called compensatory hypertrophy of the kidney. The pathogenic character of the glomerular hyperfiltration standing hereby in the centre (phenomenon of progression of chronic nephropathies) and of the final control elements influencing the residual nephrons (trade-off phenomena in chronic nephropathies) is made evident. Issuing from this the unmasking of the situations of latent glomerular hyperfiltration (GFR reserver diagnostics) is postulated as an actual task.

Adaptation, Physiological↗

Optimization of hemofilters for the development of implantable artificial kidneys.

The concept of developing an implantable artificial kidney demands, in addition to the regeneration of endogenous filtrate, a small hemofilter with a high filtration rate. Conventional capillary filters are limited in their capacity to yield adequate filtrate, even if the number of capillaries is increased. To improve filter design so as to modify flow conditions for filtration rate augmentation, it is necessary to consider such factors as blood flow through a single capillary, wall shear rate, and transmembrane pressure (ptm) in in vivo applications, where such biological considerations as blood pressure, blood flow, and flow characteristics of blood are important. These requirements lead to a completely new filter type, the "curl filter," characterized by a large effective filtration surface in a relatively small number of hollow fibers in which optimal flow conditions prevail.

Equipment Design↗

[Pathophysiologic-nephrologic hypothesis of the protective function of an endogenous natriuretic and digoxin-like substance (endoxin) for residual nephrons].

A dualistic function for the natriuretic ATP.inhibiting factor is formulated on the basis of a phenomenon like compensatory renal adaption of residual nephrons: 1. Support of the tubular sodium excretion to the maintenance of homoeostasis of the organism. 2. Inhibition of the forced up vasodilation of the afferent glomerular vessel. It should suggested that the renal vasoconstrictive effect is a part of a protective system for residual nephrons against the pathogenic hyperfiltration and hyperperfusion.

Animals↗

Low density lipoprotein binding by macroporous bead cellulose.

Cellulose of a certain macroporous structure is capable of binding selectively low density lipoproteins (LDL) whilst maintaining high density lipoprotein (HDL) levels. It was ascertained that the porous structure of the cellulose causes binding of LDL and that also diffusion processes play a role. To a certain extent special bindings such as hydrogen bonds between cellulose and LDL and/or hydrophobic interactions may furthermore be of importance for the LDL fixation.

Adsorption↗