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P Friberger

Publications and source records attributed to P Friberger.

9 recordsLinked to original sources
PubMed1979

Determination of prekallikrein in plasma by means of a chromogenic tripeptide substrate for plasma kallikrein.

A method for plasma prekallikrein determination utilizing a chromogenic tripeptic substrate is presented. The method has a good reproducibility and can easily be automized. Several parameters have been optimized. By using mixtures of deficient plasmas and pooled normal plasma or purified factors it was proved that prekallikrein was the factor determined and that more than 10% (of normal plasma concentration) of FXII and HMW kininogen were essential for the activation of prekallikrein in our method. Further experiments showed that the method was fairly selective and was not influenced by inhibitors present in normal plasma. The later finding was attributed to the high dilution of plasma made possible by using a potent activator and a sensitive substrate.

Dextrans↗
PubMed1978

Studies on the duration of local anaesthesia: a possible mechanism for the prolonging effect of dextran on the duration of infiltration anaesthesia.

The mechanism of the prolonged effect of dextran on the duration of local anaesthesia has been studied. Using radio-active mepivacaine it was found that dextran prolonged the duration of infiltration anaesthesia in guinea-pigs by delaying the absorption of the local anaesthetic agent. Experiments in vitro indicate that molecular complexes between the local anaesthetic and dextran may be formed and it is assumed that the delayed absorption might be due to the formation of such molecular complexes. This hypothesis was strengthened by experiments in which dental infiltration anaesthesias were performed in healthy volunteers.

Adult↗
PubMed1978

New chromogenic peptide substrates for factor X.

The factor Xa-sensitive substrate BZ-Ile-Glu-Gly-Arg-p-nitroanilide has been made more sensitive by making ester and amide derivatives of the gamma-carboxyl group of the glutamyl residue. The morpholinyl and piperidyl amides react 2.5 times more rapidly with factor Xa.

Factor X↗
PubMed1977

Determination of a new rapid plasmin inhibitor in human blood by means of a plasmin specific tripeptide substrate.

A method for determination of antiplasmin activity is presented. Plasmin and plasma are incubated, and the remaining plasmin activity is measured spectrophotometrically by means of the plasmin specific tripeptide substrate H-d-Val-l-Leu-l-Lys-p-nitroanilide. The method is simple, rapid and easily automatized. By the immunoadsorption technique, and with the aid of purified substances it is shown that the measured activity is mainly due to a new antiplasmin [2,4] and possibly to some extent to alpha1-antitrypsin and C1-esterase inhibitor have no antiplasmin activity in the method. Heparin and epsilonaminocaproic acid interfered with the assay.

Aminocaproic Acid↗
PubMed1975

The effect of pH upon fluoride uptake in intact enamel.

The relationship between pH and fluoride uptake in intact enamel of permanent premolars was investigated by using: (1) a sodium fluoride dentifrice, (2) a potassium fluoride + manganese chloride dentifrice, and (3) a sodium fluoride solution of the same fluoride concentration. The first part of this paper deals with the in vitro uptake of fluoride from dentifrice slurries and from sodium fluoride solutions of different pH ranging from 7.1 to 4.5. This investigation showed that there was no significant difference between the agents but that the effect of the pH was significant. The uptake of fluoride in the form of fluorapatite was more than five times larger at the lower pH level. The second part of the paper deals with the rate of fluoride uptake (increase in fluoride content) from dentifrices in the same pH range. It was shown that the three agents gave the same initial rate of fluoride uptake (about 50 parts/10(6)/min) at pH 6 and that the rate of fluoride uptake in the outer layer of the enamel was proportional to the hydrogen ion activity.

Child↗