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Biomedical subjects

L Schumann

Publications and source records attributed to L Schumann.

At least 37 records · Page 2Linked to original sources
PubMed1990

[Simultaneous determination of the GRF and the ERPF (effective renal plasma flow) using a single blood sample in the slope clearance with 99mTc-DTPA and I 131-hippurate].

In patients with various indications to renal split function diagnostics the plasma slope clearance of the Tc99m-DTPA and J131-Hippurate to the estimation of GFR and ERPF were performed with two or three blood samples in the monocompartment model (1 KM). In comparison these functional parameters were calculated on the basis of the only least blood sample (single-point procedure--EPV). The results of linear regression GFR (1 KM) = 12.7 + 0.978 * GFR (EPV), r = 0.986, N = 102 or ERPF (1 KM) = 22 + 1.13 * ERPF (EPV), r = 0.889, N = 68 may recommend the use as patient-safe procedure especially in poor venous access. Two short BASIC programs for estimation of GFR and ERPF are presented and the error ranges discussed.

Adult↗
PubMed1990

An improved method to determine renal function using inulin and p-aminohippurate (PAH) steady-state kinetic modeling.

Steady-state clearances using inulin and PAH are the most reliable reference procedures if new test substances or techniques are developed to estimate the GFR or the of these methods we developed an open monocompartment model with an expanding distribution volume of the substance of interest. In this model we derived prescriptions for the concentration of inulin and PAH in the infusion procedure. The resulting improvement was verified by the F-test on the variance of plasma concentration in a 3-hour examination of 15 patients. The final results are of direct benefit to the patient because the number of blood samples required for the control of the steady-state plasma level can be reduced. Furthermore, we derived an individual correction of the so-called input steady-state clearance (without urine collection) which relates better to the usual output clearance of inulin or PAH. A PC-BASIC program is available that calculates the proper concentrations for the infusion and executes the complete analysis (GFR, ERPF, filtrate fraction [FF], maximal tubular transport of PAH [TmPAH] and the renal vascular resistance [RVR], each of which is related to the BSA and the age of the patient).

Aminohippuric Acids↗
PubMed1989

[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↗
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↗
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

[Standardization of methods and assessment of conventional and radionuclide clearance investigations: recommendations of the Renal Diagnostics Study Group of the Society of Nephrology, GDR].

Recommendations of the Study Group "Renal Function Diagnostics" of the Society of Nephrology to the performance of the steady state clearance using inulin or PAH and the slope clearance with radionuclides for estimation of effective renal plasma flow are presented. These investigations are indicated in the early recognition and follow-up of latent or residual disturbance of the renal function in the creatinine-blind area. Recommendations have been done on selection and dosage of test substances, timing of examination and evaluation of results.

Blood Pressure↗
PubMed1988

[Development of a model as a pathophysiologic study method in clinical and experimental nephrology].

After explanations concerning principal qualities of the models follow examples from nephrology about theoretical and concrete modelling. Consequences for the renal functional, performance and reagibility diagnostics are discussed. The ability of mathematical modellings for statements is shown at the instance of the ureal plasma kinetics in apparative peritoneal detoxication methods and in connection with investigations about the implantable kidney as well as supplemented by explanations concerning the dynamic compartment modelling of the potassium balance.

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↗
PubMed1987

Bacterial and fungal growth after freezing or refrigerating parenteral nutrient solutions.

Parenteral nutrient (PN) solutions were evaluated for growth of pathogenic organisms after refrigeration or freezing and then thawing. Sixteen bags of hypertonic dextrose and amino acid solutions were divided into two series (refrigerated and frozen), inoculated with Escherichia coli. Candida albicans, Staphylococcus aureus, or Streptococcus faecalis, and exposed to freezing or refrigeration. The inoculum concentration was greater than would likely occur with patient contamination of the solution. Microbial growth in the solutions was determined after warming to room temperature and at 17 or 18 hours after reaching room temperature. There was no increased growth of C. albicans in PN solutions that were frozen versus the refrigerated samples. Counts for all of the organisms in the frozen series, immediately after freezing and then thawing, decreased or stayed the same compared with baseline counts. Growth of E. coli, Staph. aureus, and Strep. faecalis increased in the frozen samples compared with the refrigerated samples after room-temperature storage, suggesting a possible increased risk of infectious complications if contaminated solutions are left at room temperature for extended periods. Since no increased risk of microbial growth is likely in frozen versus refrigerated PN solutions that are thawed and promptly infused, batch freezing may be an effective and convenient means of preparing PN solutions for home patients.

Bacteria↗
PubMed1986

[Mediator concepts and modulation of renal compensatory adaptation].

In the renal compensatory adaptation after the definition and the description of the fundamental phenomena of the functional compensation as well as of the structural adaptation is reported on mediator concepts and on modulations of the renal adaptation processes. Issuing from the central position of the sodium balance a mediator concept on natriuretic hormones (Auriculin and Endoxin) is developed which is supplemented by the renotropin mediator concept. The authors deal with the modulation of the renal compensatory adaptation (e.g. influences of age diet and so on). The pharmacotherapeutic modulation of the renal compensatory adaptation is discussed with regard to the stimulation of the tubulosecretory transport of foreign substances with para-amino hippuric acid as principal substance (including own investigations with cyclopenthiazide [Benesal].

Adaptation, Physiological↗
PubMed1986

[Experimental animal studies of compensatory renal adaptation of residual nephrons in physical stress caused by daily swim training].

The influence of a regular physical training after unilateral nephrectomy carried out on the experimental animal rat on the function of the residual kidney was investigated. A significant decrease of the glomerular filtration rate by 22% and an increase of TmPAH by 36% in the loaded animals could be proved 12 weeks after unilateral nephrectomy and two-month load by swimming training. These findings allow the interpretation that physical conditioning for adapting nephrons may be regarded as progression as well as protection factor. Additional long-term investigations are necessary to clarify this problem and finally to prove present therapeutic recommendations for the physical conditioning with regard to prove protective reactions to the renal compensatory adaptation of the residual nephrons without any doubt.

Adaptation, Physiological↗
PubMed1985

[Renal and nephronal function diagnosis in the aged experimental rat].

An investigation method concerning the renal and nephronal functional diagnostics on the experimental animal rat without analysis of microbes, without micropuncture technique and without use of inulin or paraamino-hippuric acid-analogous radiopharmaca is demonstrated. It is based on the steady state investigation principle using inulin and paraamino-hippuric acid as test substances. The exactness of the method is established by critical considerations of the methods concerning the stabilisation of the humoral balance. by estimation of the behaviour of the functional parameters after heminephrectomy as well as by comparative valuation of the own results by findings reported in literature. The established renal and nephronal functional parameters comprise glomerulofiltrative and tubulosecretory as well as tubuloreabsorptive processes in the water, sodium and paraamino-hippuric acid treatment.

Aging↗