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At least 19 recordsLinked to original sources
PubMed1972

The partial thromboplastin (cephalin) time test.

Nine partial thromboplastin (cephalin) reagents have been compared in a parallel investigation of groups of patients on ;long-term' anticoagulants, a group with moderate haemophilia, and patients on heparin infusion. Results with the seven commercial reagents and a human cephalin extract have been correlated with those of a specially prepared and standardized reference preparation of human brain origin. The comparison was similar in principle to that of the prothrombin time thromboplastin standardization using the British Comparative Thromboplastin (BCT). Results, which for comparative purposes were expressed as ratio of patients' cephalin times to control cephalin times, varied greatly in all three groups. In the oral anticoagulant group some of the commercial reagents were particularly insensitive to the ;intrinsic' clotting defect. The correlation between the ;standardized preparation' and the other reagents was not good and the use of a reference cephalin material for quality control of cephalin time tests does not appear promising. In moderate haemophilia the commercial reagents were either relatively poor at picking out the clotting defect compared with the ;standardized preparation' or gave such a bad endpoint that the results were not dependable. The poor endpoint also limited the dependability of the results of all but the ;standardized preparation' and two of the commercial reagents in controlling heparin administration. In view of these standardization difficulties, which cannot apparently be resolved by the use of reference material, there is need for bulk, routine supplies of a sensitive, standardized cephalin reagent giving good reproducible endpoints. The method for the provision of such material in a recently introduced national supply scheme is described.

Blood Coagulation Tests↗
PubMed1990

Mixing behavior of binary insoluble phospholipid monolayers. Analysis of the mixing properties of binary lecithin and cephalin systems by application of several surface and spreading techniques.

The detailed miscibility analysis of binary phospholipid monolayers requires the application of a variety of spreading and surface techniques which often yield complementary results. Testing the equilibrium state of the binary monolayer by long-time experiments is also of great importance. Studies of the compression and spreading behavior of binary monomolecular systems form a basis for the determination of binary monomolecular phase diagrams. Within these plots different phase regions occur which permit clear statements regarding the miscibility state. Additional knowledge of the miscibility properties (phase diagrams) of the binary bulk systems is required. From the analogy of the properties of the bulk systems, the miscibility state of the monolayers is also determined by the temperature, and we can classify the monolayers of binary lecithin and cephalin systems into systems of complete miscibility, partial miscibility and complete immiscibility. In addition to the differences in the chemical structure of the mixing components, the film states in the monolayer and the miscibility behavior of the bulk systems are also influencing factors. If one of the components does not produce a spreading pressure, miscibility gaps occur in the phase diagram of the phospholipid monolayer. The miscibility gap, expressed by a constant spreading pressure, indicates complete immiscibility within this concentration range. If both components produce spreading pressures, and condensed and liquid-expanded film states within the considered temperature range, partial miscibility of the components becomes probable. The most effective parameter is then the difference in the chemical structure of the components. When both components produce spreading pressures and condensed films, the chemical structure of the mixing phospholipid compounds within their hydrophilic and hydrophobic parts is of essential importance. Depending on the differences in the chemical structures of their chains and their head groups in the case of binary phospholipid monolayers, the following possibilities result: complete miscibility, partial miscibility and complete immiscibility of the lecithins and the cephalins. Complete miscibility within the binary phospholipid monolayer takes place in the case of identical head-group structure and where there are only small differences in the chain length of the fatty acid groups. With increasing hydrocarbon chain length differences, partial miscibility or even complete immiscibility can occur within the monolayer. Chemical differences in the head-group structure of the mixing components have a similar influence. In the case of binary lecithin/cephalin mixtures, the differences in the head-group structure affect the miscibility behavior more than the chain length differences do in the case of lecithin/lecithin and cephalin/cephalin mixtures.(ABSTRACT TRUNCATED AT 400 WORDS)

Liposomes↗
PubMed2002

A blinded in vitro study with Refacto mock plasma samples: similar FVIII results between the chromogenic assay and a one-stage assay when using a higher cephalin dilution.

Assay of factor VIII (FVIII) in patient samples is routinely carried out using the one-stage assay rather than the chromogenic substrate assay. The introduction of new FVIII preparations for the treatment of haemophilia A, including immunopurified FVIII and particularly, recombinant FVIII (rFVIII) concentrates, has led to discrepancies between the results obtained with the two assays. In patients treated with rFVIII concentrates, FVIII levels measured with the one-stage assay can be 20-50% lower than those measured with the chromogenic assay. In this study, the one-stage assay was performed with cephalin dilutions higher than those recommended by the manufacturer. B-domain-deleted recombinant FVIII, Refacto, was diluted to eight different concentrations, ranging from 1-100 IU dL(-1), in FVIII-deficient plasma and the FVIII activity of the eight solutions was determined by the chromogenic method in a central laboratory. Aliquots were then assayed by the one-stage method in the four participating laboratories, using different dilutions of CK-Prest. When CK-Prest was reconstituted according to the manufacturer's recommendations (dilution 1 : 1), the difference between the one-stage and chromogenic methods was close to 30%. CK-Prest cephalin dilutions of 1 : 5 and 1 : 8 gave very similar results with the two methods, without increasing the interlaboratory coefficient of variation. These findings confirm the influence of phospholipids on the one-stage assay, particularly the importance of using a phospholipid concentration close to the physiological value in platelets. This modified one-stage method may therefore offer an alternative to the use of a concentrate-specific standard.

Chromogenic Compounds↗
PubMedDate not supplied

Free choline concentration and cephalin-N-methyltransferase activity in the maternal and foetal liver and placenta of pregnant rats.

1. The concentration of free choline and cephalin-N-methyltransferase activity of the maternal and foetal liver and placenta of rats in late pregnancy were determined. 2. The choline concentration of the liver fell from a mean of 130 nmol/g in adult non-pregnant rats to 38 nmol/g in late pregnancy. 3. The choline concentrations of the foetal liver and placenta had mean values of 135 and 442 nmol/g, respectively. 4. There was a significant 24% increase in the cephalin-N-methyltransferase activity of the liver during pregnancy. The enzyme activity in the foetal liver was 7% that of the maternal liver, and activity was undetectable in the placenta. 5. The results suggest that, during pregnancy, the maternal liver supplies choline to the placenta and foetal organs, like the liver, and that the demand for maternal liver choline far exceeds the supply available.

Animals↗
PubMed1976

[Platelets aggregation employing ADP and cephalin. Comparative tests (author's transl)].

The AA. have carried out researches into the results of the platelets aggregation test (PAT) on 375 people by use of the Born method; they have employed ADP and a commercial available cephalin (Thrombofax, Ortho). In the first case the parameters taken into consideration are: the minimum dose of ADP able to cause a "double wave aggregation", the slope and the maximum increase in light transmission; in the second case the parameters considered are: the latency period, the maximum speed and the maximum amplitude. The normal values, in 75 persons, are: --6 +/- 2 X 10(-7)M (min dose wor "double wave"); --15,5 +/- 4,9 UT/min (slope); -- 46,3 +/- 6,8 UT (max increase in light transmission); regarding ADP aggregation. --90 +/- 40 sec (latency period); -- 30 +/- 15 UT/min (max speed); -- 52 +/- 4,63 UT (max amplitude); relating to Thrombofax aggregation. Analyses of PAT, by parallel using both aggregating agents, have been made on 260 women undergoina an oestrogen-progestative therapy, on 25 daibetic subjects and on 15 subjects undergoing an anti-aggregation oral therapy (Ageroplas, Serono, Roma). The AA. stress on the validity of ADP as an aggregation agent in routine tests, while Trombofax has revealed itself to be not very sensitive in all the cases with hyperaggregation. However it is to be noted that use of cephalin results interesting in tests made on subjects undergoing an anti-aggregation therapy, as the PAT parameters seen proportional to the quantity of the drug given to the patient, which is just the opposite of what happens with ADP.

Adenosine Diphosphate↗
PubMed1981

[Comparative study of Lecithin and cephalin exchange between liposomes and mitochondria. Activity measured in the presence and absence of a non-specific carrier protein isolated from rat liver].

Study has been made of the rat liver protein catalyzed exchange of both lecithin and cephalin between liposomes and rat liver mitochondria. It has been shown that the exchange activity of these two phospholipids by the protein is almost the same and is apparently not dependent on the nature of donor liposomes. In contrast the spontaneous exchange activity of the above phospholipids strictly depends on the type of donor liposomes. Moreover, the spontaneous exchange of lecithin at any incubation time appears to be almost 100% higher than that of cephalin.

Animals↗
PubMed1985

[Congenital factor XII deficiency: a rare cause of increased activated cephalin time].

The fortuitous detection of an increased activated cephalin clotting time is often dependent on defects of the blood-clotting factors synthesized by the liver, haemophilia or von Willebrand's disease, circulating anticoagulants or specific deficiencies of various factors necessary for blood-clotting mechanisms. Much more rarely, it may be due to an isolated Hageman factor defect. This deficiency does not lead to an increased bleeding tendency and surgery has proved surprisingly uneventful. On the other hand, thromboembolic events may appear. Being and inherited disease with autosomal recessive transmission, the discovery of Hageman factor deficiency must lead to a complete family investigation.

Adult↗
PubMed1981

[Determination of the prothrombin time and of the activated cephalin time wit semi-automatic Electra 600 apparatus (author's transl)].

This work studies the quality of the response of the Electra 600 for the determination of the prothrombin time (PT) and the activated cephalin time (ACT). The intra-serial precision was good for the PT and the ACT with normal or pathological plasmas (CV 2%). The precision was excellent for the PT (r = 0.98; Electra 600-fibrometer). The correlation coefficient varies between 0.85 and 0.95 for the ACT depending on the nature of the activator chosen. Lactescent plasmas having a protein concentration greater than 85 g/l should be treated manually for measurement of the PT. No interference was noted with other biological substances: eg glucose, bilirubin, hemoglobin. The increasing addition of heparin indicates a correct sensitivity of the response with Electra 600 both for short and long ACT. Autoanalysis renders the determinations of PT and ACT independant of the manipulator, that of the PT being much more rapid than with the manual method

Autoanalysis↗