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Biomedical subjects

H Klinkmann

Publications and source records attributed to H Klinkmann.

At least 91 records · Page 5Linked to original sources
PubMed1989

[Correlation of complement activation, cytokine liberation and beta 2 microglobulin in the use of various dialysis and hemofiltration membranes].

The release of biological active factors from blood cells, e.g. interleukin 1, is of importance with regard to the bioavailability testing of membranes for extracorporeal blood purification. The data from an in vitro system of cytokine release may show a connection between complement activation and cytokine (interleukin) release of membranes. In contrast the results of the generation rate of beta 2-microglobulin did show no definite reference to complement activation or cytokine release. Further time-dependent investigations of the generation rate beta 2-microglobulin are necessary.

Biocompatible Materials↗
PubMed1989

[Steps for solutions and hindrances in progress in relation to an implantable bio-artificial hemofilter-intestine-hybrid kidney].

On the view of 1989 older and modern developments to a bioartificial implantable hybrid kidney are presented. To the realization proof of the implantable hemofilter-intestine-hybrid kidney the routes were described in an experimental rat model to the plasmakinetic simulation of the urea and sodium level as a marker of the hybrid kidney functions. The results of the bioartificial hemofilter-intestine-hybrid kidney development are presented, but significant detail problems must be solved, especially the hemofilter biocompatibility problem.

Animals↗
PubMed1989

[The growth of rats in renal compensatory adaptation in feeding with a supplemented diet of hydroxy-analogs of essential amino acids].

Rats were fed protein-restricted after unilateral nephrectomy (6.7% casein). Comparatively other animals were fed with experimental diets, at which 20% of the casein have been replaced by Ketosteril or a mixture of hydroxy acid. The constituents of this mixture are in accordance with the molar relation of all Ketosteril components. However, sodium solts of hydroxy acids of leucine, isoleucine and valin replace the corresponding keto acids of Ketosteril. The other components of the mixture consist of free amino acids. The efficiency of protein utilisation was judged by the relation of increased body weight and nitrogen intake. The efficiency of protein utilisation of both supplemented diets is 2.5 times higher compared with the casein diet.

Amino Acids, Essential↗
PubMed1989

[Studies of animal experiment models of the behavior of the glomerular filtration rate in acute changes of dietary protein consumption].

The glomerular filtration rate (GFR) and the tubulo-secretoric transport maximum of para-aminohippuric acid (TmPAH) were examined in acute feeding trials (pellets, flesh) and after infusion of furesemide, dopamin and glucagon in normal and unilaterally nephrectomized Wistar rats. The aim of the study was to investigate the start process of GFR rise in a further experimental model (apart from the hyperfiltration in residual nephrons) and to confirm the so-called paradoxical GFR changes. The investigations of acute protein-loading induced GFR changes were without results, whereas a GFR rise could observed during intraarterial infusion of isotonic saline solution. A paradoxical GFR behaviour was demonstrable under high glucagon application.

Animals↗
PubMed1989

A first screening for hemocompatibility of a universal support for selective and specific hemoperfusion.

A modified filmadsorber is presented, intended to be used for selective and specific hemoperfusion. It consists of a spirally wound cellulose nitrate film, onto which--after chemical activation with sodium periodate--albumin is bound, stabilized, sterilized and activated with glutaraldehyde. Various bioactive ligands containing amino groups can be coupled to this support. A subsequent treatment with dimethylamino borane stabilizes the bonds between cellulose nitrate, albumin, glutaraldehyde and ligand. Columns in which a second layer of albumin is bound to the support as a model for a bioactive ligand were first screened for hemocompatibility using rabbits. Leukocyte, thrombocyte and hematocrit behaviour during hemoperfusion showed that hemocompatibility of the support was good.

Adsorption↗
PubMed1988

[Plasmapheresis--an international determination of status].

The development of the therapeutic plasmapheresis reaches from the beginnings of the centrifugation technique in the early fifties and the appearance of membrane plasma filters in the late seventies up to numbers of treatment of about a quarter of a million a year all over the world. Instead of the former uncritical euphoria in the selection of patients nowadays a strict indication occupied the position. Efforts all over the world to confirm scientifically the efficacy of the plasmapheresis have not been finished up to now. Geographical differences in the diagnosis are in most cases the sequels of subjective factors of locally dominating working teams, which is demonstrated on the basis of international statistics. Specific modifications such as cascade filtration and plasma absorption are described.

Autoimmune Diseases↗
PubMed1988

[Acute oral protein administration in the diagnosis of kidney function and causal pathogenetic correlations].

In a literature review it was reported on the performance-orientated diagnostic determination of the glomerular filtration rate by acute oral protein load in man. Recommendations to the standardization of the test realisation are presented. The results of the glomerular filtration reserve--being derived from acute intraindividual changes of the creatinine short-term clearance after an oral protein load--are described in dependence on the renal starting situation. The causal-pathogenetic relations are represented in consideration of the natriuretic hormone and of the pathophysiological model character of the GFR-provocation test to hormonal starting processes, respectively.

Creatinine↗
PubMed1988

[Determination of clearance for urea-controlled hemodialysis].

Through a simple variant of the urea model the qualitative influence of the dialyzer-clearance on the individual dialysis guidance is elucidated. Realization of the respective Kdtd/V-value require an exact knowledge of the in-vivo-urea-clearance of all available dialyzer types and their manipulation with the aid of blood flow. The theoretical connections are explained and possible parameters affecting the in-vivo-clearance are discussed. The results concerning the dependence of urea-clearance on the blood flow are presented in an urea-guided dialysis patient pool for all in the GDR customary in the trade or temporary available dialyzers. It is shown, that in MLW-dialyzers an influence on the urea-clearance about the blood flow is small because of their relatively thick-walled membrane. Therefore, the development of dialysis membranes with superior diffusible permeability is necessary.

Blood Flow Velocity↗
PubMed1988

A simplified procedure to compute dialysis time and frequency by means of urea kinetics.

A simplified urea model is presented based on the concept of the time-averaged deviation (TAD) of the blood urea concentration and the introduction of an effective urea generation rate. The increase in the interdialytic blood urea concentration delta c is specific for the individual patient and includes the urea generation rate, distribution volume and residual kidney clearance. By measuring delta c of the largest interdialytic interval of the week the treatment frequency and duration can be calculated. Even for larger residual clearances Kr less than or equal to 5 ml/min this calculated treatment time does not differ by more than 5 min from the result of the exact urea kinetics. In vivo estimation of the urea clearances versus blood flow for the dialyzer types used is necessary for the application of urea modelling in clinical practice.

Blood Flow Velocity↗
PubMed1988

[Hemocompatibility testing in the rat model by noninvasive blood flow measurement using an arteriovenous shunt].

The flowing periods of blood through biomaterial shunts were measured by means of a noninvasive sensor with sufficient reliability. Falsifications of the measuring results by foreign influences as roller pumps, punctures, changes of the cross section, or the coupling of different materials were avoided extensively. The accomplishment of the test is possible routinely without a great display of apparatus.

Animals↗
PubMed1988

[Correlations of homeostatic disorders of tubule function, type of clinical course of chronic glomerulonephritis and histologic changes in the diagnosis of tubulo-interstitial lesions].

In 366 patients with bioptical verified and functional compensated chronic glomerulonephritis the relations between the clinical course types of glomerulonephritis according to Ratner, the histological changes and the tubular homoeostatic parameters of renal function, respectively, were investigated. A reliable connection was found between the clinical course type and special tubular functional parameters. With reference to histological changes the occurrence of a tubulo-interstitial lesion (tiK) is the cause of an excessive disturbance of the renal tubular function. Independently of this, however, the clinical course type of chronic glomerulonephritis may be responsible for the pathological reactive failure of tubular functional parameters. In the case of renal tubular dysfunction in the active nephritic type (ANT) and the nephrotic type with hypertension (NHT), respectively, the occurrence of a tik is much likely. By the lack of reno-tubular dysfunction in ANT and NHT a tik be cannot excluded. In contrast to this, in the inactive nephrotic type (INT) and the nephrotic type without hypertension (NHT), respectively, a tik be can excluded by lack of tubular dysfunction. On the other side, a tubular dysfunction in these groups is not a certain proof of a tik.

Adolescent↗
PubMed1988

[Contribution of animal experiments in the problem of a long-term indomethacin therapy in advanced nephron loss].

Residual nephrons are subject to compensatory adaptation at which the glomerular hyperfiltration and convection of macromolecules (proteins) are of pathogenic character in the progression of nephropathy. The influence of indomethacin at dosages of 2 or 3 mg/kg body weight/day was investigated in long-term feeding trials (8 months) on inbred female Wistar rats after unilateral nephrectomy and additional resection of both kidney poles. The results show a significant deterioration of vital prognosis under indomethacin medication independently of the dosage.

Animals↗
PubMed1988

[Hemorheological/hemodynamic study on miniaturized capillary filters in the concept of an implantable artificial kidney].

The conception of an implantable kidney provides the substitute of the non-functioning kidney by a technical-biological system. The filtration function is to be performed by a capillary hemofilter. The results obtained in an open test circulation on 3 filters produced by optimum aspects were represented and compared with the physiological performance parameters of the kidney. The special importance of the construction of the flow conditions in the single capillary is accentuated as the fundamental aspect for additional optimization. An optimized capillary filter produced the necessary filtration rate for maintaining the homeostasis on condition of a low-protein diet and an increased level of blood urea. The changes of the hemorheologic parameters is to come up by an adequate absorption of fluid in the colon.

Capillaries↗
PubMed1988

[Modelling and simulation of urea balance in a rat model on the condition of large intestine infusion analogous to the ultrafiltrate as a contribution to the development of an implantable intestinal hybrid kidney].

The urea kinetics in blood plasma is discussed for the animal model in rats in the development conception of an implantable artificial kidney, in which the filtration process is received energetically endogenically by a technical hemofilter whereas the ultrafiltrate procedure takes place by intestinal reabsorption and elimination of the end-products. The underlying monocompartment model contains the elements plasma, hemofilter, intestine including their urea turnover rates. Further on a special model conception is developed for the animal experimental designation of the selective urea reflecting power of the intestinal mucosa. The hemofilter-intestine-hybrid kidney-system has chanced to be in order if the experimentally ascertained quantities of the preliminary experiments will be inserted simultaneously for essential parameters in the model experiment.

Animals↗
PubMed1988

[The selective elimination function of the colon in a rat model for the substances water and urea in long-term experiments as a contribution to the development of an implantable hemofilter-intestine-hybrid kidney].

The investigations on the selective elimination and preservation function of the colon represented one of the numerous problems in the development of an implantable hemofilter-intestine-hybrid kidney. The assumption of an ideal reflection of urea on the intestinal mucosa and the ability of water absorption of the colon had to be checked. A fluid which is nearly analogous to the ultrafiltrate with different urea concentrations was infused into the colon of rats by a cecocutaneous catheter fistula during two-phasic long-term experiments. The renal and enteral urea elimination rates were defined. The apparent reflection coefficient for urea of the colon amounted 0.5 to 0.6 in an infusion rate of 80 ml/day. The ability of water absorption of the colon in rats of nearly 300 g of weight could be increased up to 200 ml/day during slow and continuous adaptation in the infusion quantity.

Animals↗
PubMed1988

[Extracorporeal blood circulation in the unanesthetized free-moving rabbit--an animal model for biocompatibility studies].

The rabbit is suitable as a basis model for the extracorporal circuit (ECC) in long-term test (20 days). A decrease of the leucocytes and platelets is established already in the blank test qualified by catheter material and pumping influence. This effect can be compensated by the rabbit in long-term test. The typical decrease of the leucocytes and platelets does not show any significant alteration during many test days independent of the number of tests which were carried out in one rabbit (blank test and hemoperfusion). A hemoperfusion across activated carbon--independent of the albumin coating--leads to a significant decrease of the leucocytes in comparison to the blank test. This rabbit model is well-suitable for biocompatibility investigations respectively also for effective investigations of detoxication techniques taken as a basis of our results.

Animals↗