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Biomedical subjects

U Schmidt

Publications and source records attributed to U Schmidt.

At least 487 records · Page 27Linked to original sources
PubMed1977

Na-K-activated ATPase: activity maturation in rabbit nephron segments dissected in vitro.

Single, defined nephron segments were dissected in vitro from fresh slices of neonatal and mature rabbit kidney. Na-K-ATPase was quantified for six different tubule segments with an ultramicromethod. The enzyme distribution pattern in the neonatal nephron was similar to that in the mature nephron. Activity in distal segments was 2-5 times higher than proximal tubule activity referred to tissue dry weight, and 2 times higher referred to tubule length. Neonatal enzyme activity was lower than mature in all segments. Some segments carried only 23% of mature activity. Enzyme activity in the proximal convoluted tubule was constant during maturation when referred to the basal and lateral membrane area measured in the same developmental stages. In vitro activities of these tubules were similar to the enzyme activity measured previously in freeze-dried slices. The Vmax during development of Na-K-ATPase was higher by a factor of 5 in the mature tubule, whereas the Km was identical in the neonatal and mature tubule. The ouabain-insensitive ATPase did not show a maturational activity change.

Adenosine Triphosphatases↗
PubMed1977

[Highly effective short-term dialysis with two parallel-connected capillary dialysators type C-DAK4. 2. Clinical parameter, subjective symptoms and performance control of patients compared to conventional dialyses].

8 male patients with chronic dialysis (5 of them with binephrectomy) were thrice a week dialysed in 2 groups alternately 2 months conventionally for 6 hours with a capillary dialysator C-DAK mod. 4 and 2 months for 3 hours with 2 parallel connected C-DAK 4. In a constant square metre-hour-product (23.4 m2h/week), homogeneous criteria of treatment and, as a rule, four times repeated use of the C-DAK 4 clinical parameters, subjective complaints and efficiency of the same patients were compared.

Blood Transfusion↗
PubMed1977

[Comparison of repeated use of capillary dialysators model C-DAK 4 and C-DAK 5].

18 dialysators C-DAK 5 and 4 each were again used in the same patients with chronic dialysis under the same conditions of dialysis and regeneration (short-acting dialyses of more than 3.5 h with 1 C-DAK 5 or 2 parallel acting C-DAK 4, respectively). A volume of the blood compartment of more than 70% of the initial value was regarded as criterion for the further usability. Thus, model 5 could be used on an average 3.7 times, model 4, however, 6.3 times (p less than 0.0001). Already at the end of the 3rd use in model 5 the capillary volume decreased below 63%, in model 4 only below 88%. The volumetrically determined ultrafiltration showed a decrease parallel to the volume of the blood compartment -- with the same differences between the two models of the C-DAK. In model 15 the effectiveness concerning the elimination of creatinine and urea clearly decreased after the 2nd use, whereas it did not reveal a change also in an application four times repeated. The larger coagulation processes in a more than once repeated use of the C-DAK 5 -- with adequate losses of blood -- are explained with the large length of the capillary and the other distribution of blood with regard to the cross section of the capillary. Summarizing we can say that in chronic routine dialyses -- without testing the individual exemplars -- model 5 of the C-DAK can be used twice, model 4, however, four times.

Creatinine↗
PubMed1976

[Isolated ultrafiltration with dialyzer and blood pump in hydropic cardiac insufficiency].

The authors indicate the possibility of an "Isolated Ultrafiltration" in cardiologic patients only with the transportable blood conducting part of the artificial kidney. The loss of oedema fluid by ultrafiltration of the blood is about 500 ml/h using a twin coil dialysator "Keradenta", or, resp., more than 1,200 ml/h using a Hollow Fibre Artificial Kidney "Dow Cordis" Mod. 5 or two HFAKs Mod. 4 in parallel. The method should be practised only in such cardiologic patients, in whom a drug-resistent hyperhydration including hypervolaemia is not a sign of a sure terminal state.

Edema↗
PubMed1976

[The clinical value of 51 chrome-EDTA clearance].

In routine diagnostics the glomerular filtration rate was in most cases determined by endogenic creatinine clearance. Possibilities of errors in this method are unreliable accumulation of urine, influencibility of the creatinine values by the muscular mass and various exogenic factors. The chromium-51-EDTA-clearance is to be regarded as a more exact method. After single intravenous injection of about 150 muCi Cr-51-EDTA (single-shot-method) the impulse rates in the serum are measured after 60, 100, 140 and 180 min in the bore-hole-crystal. Up to now the number of patients examined is about 300, additionally 6 persons who underwent binephrectomy. Elaboration of a computer programme for the calculation of the clearance values. The best approach is achieved by non-linear regression. There exists a reciprocal connection between serum creatinine and Cr-51-EDTA-clearance. Values lower than 90 ml/min must be regarded as pathological. The Cr-51-EDTA-clearance is particularly valuable in the so-called creatinine-blind region, in which it gives a more reliable information about the beginning reduction of the glomerular filtration rate, as calculation of the correlation and repeated examinations show. The method can be recommended for the clinical routine diagnostics.

Chromium Radioisotopes↗
PubMed1976

Tubular Na, K-ATPase deficiency, the cause of the congenital renal salt-losing syndrome.

In the serum of two infant sisters with a congenital renal salt-losing syndrome, Na was rather low and K considerably increased. Even with Na levels of 126 mval/1, sodium was excreted in the urine. Creatinine and hippurate clearances were normal. Primary disturbances of the steroid metabolism were not detectable; plasma cortisol was normal, aldosterone and renin were compensatorily increased. Treatment with DOCA was unsuccessful. Whereas the first infant died (in another hospital), the second one throve well with high oral substitution of NaCl. There was no pathological findings other than a moderate hyperplasia of the juxtaglomerular apparatus, in a kidney biopsy. Except for minimal activity in the ascending limb of Henle's loop, there was no membrane bound Na, K-ATPase in the microdissected tubules. This finding most probably explains the renal salt loss, as this enzyme is necessary for the transcellular flow of sodium and potassium.

Adenosine Triphosphatases↗
PubMed1976

[Mg dependence and other properties of fructose-1, 6-diphosphatase and glucose-6-phosphatase in various organs of cattle].

The properties of fructose-1.6-disphosphatase in supernatant of homogenate of liver, kidneys, and adductor muscles of cattle were tested. EDTA was found to activate the enzyme up to concentrations of 10 mMol. The pH optimum was 7.5 in the presence of EDTA. Even lower concentrations of magnesium ions caused activation of the enzyme, but an activating effect was obtained as well from relatively high Mg concentrations. Fructose-1.6-diphosphatase could by activated also by 0.2 mMol Mn or Co ions or 1 mMol Zn ions. Inhibitive action was obtained from Cu, Cd, Pb, and Hg ions. Microsomal fractions of cattle liver and kidney caused high activity of glucose-6-phosphatase, but only low action was obtained be using microsomal fractions of mesenteric mucous membrane or brain. Mg ions, basically, failed to trigger activation, and higher concentrations even caused inhibition. The relatively high activity of both fructose-1.6-diphosphatase and glucose-6-phosphatase in kidney of cattle appeared to suggest an involvement of those enzymes in gluconeogenesis.

Animals↗
PubMed1976

Visual acuity of the vampire bat, Desmodus rotundus, and its dependence upon light intensity.

The visual system of microchiropteran bats is usually considered of minor function, but reliable experimental studies are rare. In this paper the visual acuity of three (1 female, 2 male male) vampire bats (Desmodus rotundus) has been investigated in a two-choice training apparatus (striped patterns vs. gray patterns) for light intensities from 0.04 1x to 310 1x. There was a logarithmic dependence between light intensity and visual acuity. The lowest visual angle at 0.04 1x was 2 degrees 31', at 310 1x the minimum resolvable stripe width was 48'.

Animals↗
PubMed1976

Liver cell heterogeneity. The distribution of pyruvate kinase and phosphoenolpyruvate carboxykinase (GTP) in the liver lobule of fed and starved rats.

Pyruvate kinase and phosphoenolpyruvate carboxykinase activities were determined in microdissected freeze-dried liver cells from the periportal and pericentral area of the liver lobule. Pyruvate kinase activity was measured by a microfluorimetric procedure adapted to 20-200 ng tissue dry weight. In livers from fed rats, its activity was twice as high in the central zone as in the periportal cells; starvation reduced this gradient by decreasing central activities. Phosphoenolpyruvate carboxykinase activity was measured by a microradiochemical technique in 100-300 ng tissue dry weight. In livers from fed rats, this enzyme was nearly 3 times more active in the periportal cells than in the central area. Starvation increased this enzyme in both zones with a more pronounced change in the central cells. The results indicate a heterogeneous distribution of enzymes of carbohydrate metabolism in the liver lobule. Gluconegenesis seems to be localized preferentially in periportal hepatocytes, whereas the glycolytic enzyme was found to be more active in cells surrounding the pericentral liver cells.

Animals↗