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Biomedical subjects

M Lie

Publications and source records attributed to M Lie.

11 recordsLinked to original sources
PubMed1978

On use of chromogenic substrates for studies of coagulation inhibitors.

Methodological problems encountered using chromogenic substrates on thrombin and Xa are discussed: (1) influence of substrate on inhibitor; (2) influence of heparin; (3) optimal concentrations; (4) specificity; (5) denatured enzymes, and (6) natural versus chromogenic substrates.

Antithrombins↗
PubMed1977

Effect of glycine and glucagon on glomerular filtration and renal metabolic rates.

A rise in glomerular filtration rate (GFR) during saline infusion increases outer medullary more than cortical metabolic rate. To determine whether other GFR-increasing agents have a similar effect, renal metabolic rates were estimated by the heat-production technique during infusion of glycine or glucagon. Glycine and glucagon increased GFR by 17 +/- 2 and 32 +/- 2%, renal blood flow (RBF) by 34 and 21%, and outer medullary metabolic rate by 42 +/- 3 and 59 +/- 4%, respectively. Cortical metabolic rate rose by 7 +/- 1% during glucagon, and it increased by 29 +/- 2% during glycine infusion, suggesting a stimulation unrelated to sodium reabsorption. To determine whether glucagon influenced renal metabolism independent of its GFR-increasing effects, vasodilation was achieved by ureteral or suprarenal aortic constriction. Glucagon was without effect on RBF, GFR, and metabolic rate, but infusion of acetylcholine still raised RBF. We conclude that glucagon increases GFR by dilating vascular segments participating in autoregulation, and that energy-requiring NaCl reabsorption in the outer medulla is increased secondary to increased delivery of NaCl.

Acetylcholine↗
PubMed1977

Renal energy metabolism and sodium reabsorption after 2,4-dinitrophenol administration.

2,4-Dinitrophenol (DNP) (10 mg/kg body wt i.v.) increased renal cortical and outer medullary heat production rates and oxygen consumption by 70-90% in anesthetized dogs over a 90-min observation period without exerting any natriuretic effect. To examine whether DNP inhibited proximal reabsorption and increased distal delivery, ethacrynic acid (3 mg/kg body wt) was infused during maximal DNP effect. Sodium reabsorption fell by 14 +/- 6% in the cortex and 55 +/- 8% in the outer medulla, not significantly different from control experiments without DNP. Conversely, after ethacrynic acid administration, DNP had no additional natriuretic effect. Since DNP did not stimulate renal anaerobic metabolism (no lactate release), the effect of DNP was examined during hypoxia induced by intravenous infusion of NaCN (0.2 mumol/kg body wt-min) until renal metabolic rates fell. Subsequent infusion of DNP reduced tubular sodium reabsorption from 90 +/- 2 to 78 +/- 6%. Thus, DNP may raise renal metabolic rates by 70-90% without inhibiting sodium reabsorption, but, under conditions of hypoxia, DNP reduces sodium reabsorption and increases sodium excretion.

Anaerobiosis↗
PubMed1976

A simple amidolytic method for the determination of functional active antithrombin III.

A simple amidolytic method for the determination of the concentration of functionally active antithrombin III is described. Plasma is diluted with buffer containing EDTA and Polybrene. In stage I, diluted plasma is incubated with thrombin. EDTA retards fibrin polymerization, and plasma fibrinogen does not influence the assay. Polybrene makes the assay result independent of heparin. In stage II, remaining thrombin is determined with the chromogenic substrate benzoyl-Phe-Arg-p-NA. The method is simpler and has a higher accuracy than clotting methods. There is a close correlation between the results obtained with this assay and with immunoassay of antithrombin III.

Antithrombins↗
PubMed1976

Heparin cofactor activity and antithrombin III concentration in plasma related to age and sex.

Heparin cofactor activity and antithrombin III (At-III) concentration were measured in plasma from 219 healthy men and 177 women. Narrow ranges for heparin cofactor activity and At-III concentration were found. The standard deviation for heparin cofactor activity in men and women was 8.6 and 10.1, respectively, for At-III concentration 10.4 and 12.5. In men, mean heparin cofactor activity and mean At-III concentration decreased significantly with increasing age. In women, mean heparin cofactor activity and mean At-III concentration tended to be lower in fertile age. Hereditary At-III deficiency was detected in one individual.

Adolescent↗