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Biomedical subjects

W Niedermayer

Publications and source records attributed to W Niedermayer.

At least 37 records · Page 2Linked to original sources
PubMed1984

Separation of diploid from aneuploid cells in acute lymphoblastic leukaemia.

A new method for the separation of diploid and aneuploid cells from blood of patients with leukaemia is described. Density gradient separation using a modified silica particle gradient was combined with analysis of cellular DNA content by flow cytometry. Submicroscopic levels of diploid or aneuploid cells were enriched up to 90% purity. Three patients with acute lymphoblastic leukaemia and no evidence of aneuploid cells after separation are in continuing complete remission after 24.5-47 months. Two patients with aneuploid cells detected after separation expired in relapse 0.5 and 3 months later. Cell separation prior to flow cytometric analysis might be a useful tool to detect submicroscopic levels of aneuploid leukaemic cells in blood and bone marrow, and to predict impending relapse.

Aneuploidy↗
PubMed1984

Effect of diuretics on the tubuloglomerular feedback response.

To study the influence of diuretics on the tubuloglomerular feedback mechanism, early proximal stop-flow pressure (SFP) was measured during loop exposure to different drug concentrations. SFP was recorded continuously during arrested flow and at a perfusion rate of 50 nL/min. The perfusate consisted of isotonic saline, to which varying amounts of furosemide. bumetanide, piretanide, or hydrochlorothiazide were added to obtain final concentrations between 10(-6) and 10(-4)M. The loop diuretics furosemide, bumetanide, and piretanide showed inhibition: an inverse log-linear relation between the luminal concentration and the respective feedback response. No differences between the dose-response curves of furosemide, bumetanide, or piretanide could be demonstrated. The effective concentration range was between 10(-6) and 10(-4)M, the mean effective dose (ED50) was close to 10(-5)M for each of them. In contrast, hydrochlorothiazide did not alter the feedback response. The effect of loop diuretics was rapidly and repeatedly reversible.

Animals↗
PubMed1983

Near fatal percutaneous paraquat poisoning.

A fatal paraquat poisoning can occur when relatively large areas of skin are contaminated with a concentrated solution of paraquat (Gramoxone). A paraquat absorption takes place of the same magnitude as that with an equal dose per os. In the presence of mechanical or chemical lesion of the skin the percutaneous paraquat absorption is distinctly enhanced.

Accidents, Home↗
PubMed1983

Dose-related effects of furosemide, bumetanide, and piretanide on the thick ascending limb function in the rat.

To assess the action of piretanide, bumetanide, and furosemide on the thick ascending limb of Henle's loop, perfusion experiments were performed on rat kidneys, using a recently developed conductivity microprobe for the analysis of distal tubular fluid. Surface nephrons were perfused downstream from a solid paraffin block through Henle's loop with isotonic saline solution containing either 10(-6), 3 X 10(-6), or 10(-5) mol/L piretanide, bumetanide, or furosemide, respectively. For control values, diuretic-free saline was used. Conductivity measurements of early distal tubular fluid were performed in situ with a conductivity microprobe and were recorded continuously during variations of loop perfusion rate. A recently described micro-stop-flow technique was used to measure the conductivity of fluid emerging from the ascending limb, thereby evaluating the amount of sodium chloride reabsorbed. A significant electrolyte transport inhibition occurred within the concentration range between 10(-6) and 10(-4) M. Bumetanide and piretanide were slightly more effective than furosemide. Luminal diuretic concentrations of 10(-6) M or below were without influence on electrolyte reabsorption. Concentrations of 10(-4) M resulted in complete inhibition of the diluting segment electrolyte transfer.

Absorption↗
PubMed1982

Is the erythropoietin-hematocrit feedback control operative in chronic renal failure?

Transfusion studies in 23 chronic uremic patients with low hematocrit (HCT) values showed that (1) the pretransfusional immunodetectable (id) serum erythropoietin (EP) levels were within the normal range for healthy people; (2) the posttransfusional idEP levels remained unchanged; (3) 3 patients with analgesic nephropathy and high pretransfusional bioassayed (bio) EP levels had markedly suppressed posttransfusional bioEP, 6 patients with other kidney diseases had undetectable bioEP levels; (4) the raised pretransfusional reticulocyte (RETI) counts were markedly reduced by transfusions in all patients. We conclude that, in chronic uremic patients with elevated pretransfusional levels of bioEP, the bioEP is positively correlated with the kinetics of RETI and negatively correlated with the HCT. This correlation was not found for idEP.

Blood Transfusion↗
PubMed1981

[Renal hypertension in aortic stenosis].

Report of the clinical, biochemical, hemodynamic and x-ray data of a girl, 16 years of age, who had a narrowing of the abdominal aorta (diaphragmatic type). The stenosis was proximal to the renal arteries and was associated with unobtainable arterial pressure in the lower extremities and with hypertension in the arms. Although mechanical factors seemed to play the primary role in the production of hypertension, a further important factor inducing hypertension was the activation of the renin-angiotensin-aldosteron-system caused by reduced renal circulation.

Adolescent↗
PubMed1981

Peripheral haematocrit modulates erythropoietin production and kinetics of reticulocytes in chronic uraemic patients.

Determination of reticulocytes (RETI), haematocrit (HCT) and serum erythropoietin (by radioimmunoassay = EP-RIA) before and after transfusions of 500ml red blood cells (RBC) into 15 chronic uraemic patients demonstrated that there was a converse relation between both of these, EP-RIA and RETI, and the HCT. The same conditions were found in cases of spontaneous bleeding. This pattern of reaction of RETI, EP-RIA and HCT suggested a feedback circuit, operative between these three parameters in chronic uraemic patients.

Blood Transfusion↗
PubMed1980

Measurement of total body water in patients on maintenance hemodialysis using an ethanol dilution technique.

The applicability of the ethanol dilution (ED) technique for total body water (TBW) determination in uremic patients was studied. 73 TBW measurements were performed on 28 patients. As the basic parameters underlying the ED technique showed nearly normal values (Widmark factor r = 0.722 plus or minus 0.0786, normal = 0.710 plus or minus 0.090 g/kg; beta 60 = 0.121 plus or minus 0.037, normal = 0.140 plus or minus 0.018 g/kg x 60 min; "rectilinear' course of the blood ethanol elimination curve), the ED technique for TBW measurements is well applicable to uremic patients. Subclinical hyperhydration was diagnosed (TBW = 57.88 plus or minus 8.08% of body weight, normal = 52.6 plus or minus 5.4%) in 61% of the cases.

Adult↗
PubMed1980

Is there a dissociation of erythropoietic proliferation and serum erythropoietin levels in renal failure patients on longterm haemodialysis treatment.

The demonstration of a sustained erythropoietin (EP) -- haematocrit (HCT) feedback mechanism would underline the importance of EP as a stimulant agent for the erythropoietic proliferation (EPRO) in chronic uraemia. Hypertransfusion showed a significant suppression of EPRO without a concomitant suppression of the pretransfusional immunodetectable (id) serum EP levels. We conclude that idEP is not the major direct mediator of EPRO in short term regulatory mechanisms in the anaemia of uraemia.

Erythropoiesis↗
PubMed1979

Are erythropoietin levels in uraemic patients on haemodialysis dependent on the kidney disease and the duration of haemodialysis treatment?

Determinations of immuno-detectable Erythropoietin (idEP), haematocrit (Hct), reticulocyte counts (RC) and serum iron (SI) in uraemic patients with different kidney diseases (KD) and various lengths of chronic haemodialysis treatment (HDT) revealed firstly that all patients had normal idEP, except for analgesic nephropathies who had significantly higher idEP levels; secondly that over six years of haemodialysis idEP increased by about 40% but without concomitant Hct improvement and thirdly that there were no clear interdependencies between Hct, SI, RC and idEP in uraemic patients. In conclusion, inhibitors of erythropoiesis seem to be a major pathogenetic factor in renal anaemia besides a relative deficit in idEP.

Analgesics↗
PubMed1977

[Folic acid substitution in advanced renal disease (author's transl)].

The plasma content of folic acid was evaluated in 27 patients with advanced renal disease. There were no significant morphologic changes within the erythrocyts of the peripheral blood and bone marrow. The hematologic response of the reticulocyts, hemoglobin and hematokrit were studied after oral treatment with folic acid. There was a significant reticulocytosis at the 5th to the 8th day after initiating the oral treatment. This reaction underlines a definite, mainly nutritional (latent) folic acid deficiency being one cause for the renal anemia in these patients. A subsequent rise of the hemoglobin or hematocrit did not occur. Further possible causes for these clinical data are being discussed.

Adult↗
PubMed1975

[Activation of the fibrinolytic system by furosemide (author's transl)].

Intravenously administered furosemide induces besides its well known diuretic effect a significant activation of the fibrinolytic system. This fibrinolytic effect, however, is only seen in persons with an intact renal system, not in nephrectomized patients and not in patients with chronic renal insufficiency. From this finding the conclusion is drawn that furosemide needs for its fibrinolytic effect the intact renal tissue. It is discussed that the beneficial therapeutic value of high-dose furosemide in acute renal insufficiency following shock or septic abortion might at least partially be due to furosemide-induced fibrinolysis of the microthrombi of the glomerula.

Abortion, Septic↗