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Biomedical subjects

M Martin

Publications and source records attributed to M Martin.

At least 955 records · Page 53Linked to original sources
PubMed1976

The effect of antioxidants on the production of volatile nitrosamines during the frying of bacon.

In model system studies simulating the frying of bacon a considerable variation in the production of N-nitrosopyrrolidine (NOPyr) has been observed, as occurs in sliced bacon fried conventionally. The inclusion of ascorbate or erythorbate (isoacorbate) has led consistently to a fall in or an elimination of NOPyr production up to an addition of 300 ppm (1,5 mM). Above this concentration of ascorbate, the elimination of NOPyr formation persisted in some instances but in others an increased production of the nitrosamine occurred. Using alpha-tocopherol, a fall of NOPyr production during the simulated frying of bacon was obtained with increase of concentration of the antioxidant, there being a consistent elimination of the volatile nitrosamine following an additionof 500 ppm (1.16 mM). Whilst ascorbyl palmitate had a similar action in reducing or eliminating NOPyr production, no synergistic effect between it and alpha-tocopherol was noted in an experiment combining the two antioxidants. When bacon was fried in fat containing 400 or 800 ppm alpha-tocopherol, the total production of NOPyr and DMN in the fried bacon, cooked out fat and condensate was markedly reduced but not completely eliminated as in the model system studies. Similarly, the curing of bacon with a brine containing a mixture of alpha-tocopherol, ascorbyl palmitate and citric acid has led to considerable reductions in NOPyr and DMN output on frying when the combined concentrations of the two anti-oxidants were calculated to be 800 ppm.

Animals↗
PubMed1976

On the reliability of plasminogen measurement employing the proactivator-activator converting method.

A simple plasminogen determination method is presented. It is based upon the conversion of plasminogen into activator by large and constant amounts of streptokinase. The activator contained in a standard coagulum consisting of bovine fibrin, streptokinase, and a 1:40 dilution of human plasma converts the plasminogen adsorbed on bovine fibrin into plasmin. Lysis of the test coagulum is hereby induced. The speed of such lysis is limited by the concentration of the activator incorporated in the test coagulum. The variable component of the activator being human plasminogen, the speed of lysis is directly dependent upon the concentration of human plasminogen in the standard coagulum. Using the thromboelastograph according to Hartert in recording the test clot lysis times, this method of plasminogen determination was shown to be a simple and quick procedure. The standard deviation ranged from +/- 13,2 tp 68%, depending upon the plasminogen value to be measured (lower rates of error were attached to high, and higher rates of error to low, plasminogen concentrations). The biological variation of plasminogen values in a group of 26 men aged from 40 to 65 years was calculated to be +/- 21%. Both plasminogen and plasmin, its activated form, were exchangeable in the test, i.e. plasminogen determinations performed by activator assay did not differentiate between plasminogen and plasmin. There was no influence by varying anti-SK titers in the plasma up to a circulating antibody content of 2 million. Furthermore, plasma antiplasmins did not affect the plasminogen measuring system. Plasminogen tested by activator assay displayed values closely related to those achieved by immunochemical methods. Plasminogen measurements were performed in patients undergoing streptokinase and urokinase infusion treatment. 5,000 u streptokinase per hour, as well as 270,000 CTA-u urokinase per hour, infused over a period of 2 days produced a fall in plasminogen down to 30-60% of normal. In contrast, 100,000 u streptokinase per hour lowered the plasminogen concentration down to values of below 1%. The foregoing data indicate that plasminogen measurement, according to the principles outlined here (activator assay), may be regarded as a valuable and reliable method for the routine control of streptokinase and urokinase therapy.

Adult↗
PubMed1976

Studies on activator formation in human plasma with streptokinase. III. Investigation of activator kinetics in undiluted plasma in terms of urokinase equivalents.

A new method is presented for estimating the activator (plasminogen-streptokinase complex) concentration in native plasma of patients undergoing streptokinase infusion. The principle of the method is based on clot lysis time as recorded by the thromboelastograph. The test clot constituents were bovine fibrinogen, bovine plasminogen, EDTA, human plasma (with unknown activator concentrations), and thrombin. In order to obtain a standardization line, urokinase dissolved in NaCl solution was substituted for patients' plasma. Thus, each lysis time could easily be converted into urokinase equivalent (CTA-u/ml). Streptokinase and plasminogen molecules in undiluted patients' plasma were found to exist both in an activator-bound (equimolar plasminogen-streptokinase complex) and in a freely circulating form. This result is in agreement with earlier findings where the activator complex was demonstrated to be a widely dissociated complex in highly diluted plasma of patients, thus displaying an ample proportion of free streptokinase and plasminogen and molecules. Streptokinase treatment using dosage schemes of 100,000 u SK/h, and 200,000 u/h were monitored by quantitative activator, streptokinase, and plasminogen measurements. An average activator concentration of 50-100 CTA-u/ml and a SK-concentration of 7-16 u/ml were recorded during streptokinase infusion. Plasminogen values averaged 0.25%, independent of the amount of streptokinase infused. Each drop in streptokinase was accompanied by a drop in activator during the infusion, and each rise in streptokinase by a rise in activator. There was a strong correlation between streptokinase and activator concentrations in that, on the average, 1 u streptokinase equalled 8.4 CTA-u/ml activator (correlation coefficient r = 0.9) It is concluded that the activator concentration in the plasma of patients undergoing fibrinolytic treatment can easily be adjusted by regulating the hourly streptokinase influx.

Endopeptidases↗
PubMed1976

[Acoustic trauma].

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Dental High-Speed Equipment↗
PubMed1976

[The accuracy of ophthalmodynamometry in the diagnosis of occlusions of the carotid artery (author's transl)].

The aim of this study was to evaluate the diagnostic accuracy of ophthalmodynamometry in cases of occlusion of the internal carotid artery. Among the 29 patients examined with ODM there were 12 cases of such an occlusion, which were unknown to the ophthalmological examiner. All of them could be diagnosed exactly. When by means of ODM an occlusion in the region of the common or internal carotid was excluded the result was equally accurate. A decrease in ophthalmic blood pressure by 15% or a side difference of the same degree indicated in 80% of the cases an occlusion of the internal carotid. The ODM seems, therefore, to be a suitable test for finding or excluding such an occlusion.

Adult↗
PubMed1976

Theoretical interstellar and prebiotic organic chemistry: a tentative methodology.

A theoretical methodology for the systematic study of the interstellar molecules is proposed. Some examples, dealing with formaldehyde excited states, formyl radical and ion, reactivity of the excited states of formic acid, methyl cyanide and methyl acetylene, as well as the reaction patho of formaldehyde photodecomposition are presented. Quantum chemical methods appear to be a powerful tool to study the structure and behaviour of molecules related with interstellar space and the Origin of Life.

Acetonitriles↗
PubMed1976

Circulating antibodies in rats bearing grafted colon carcinoma.

Sera from rats bearing primary or grafted colon carcinoma may contain antibodies that can react with antigenic determinants at the surface of cultivated colon cancer cells. Assays with various target cells and absorption experiments suggest that antigens recognized by circulating antibodies are common to independent lines of cultivated colon cancer cells. They are therefore cross-reacting, tumor-type-specific antigens. They could be embryonic or fetal antigens, because some sera from multiparous animals react with colon cancer cells. However, blocking experiments suggest that these antigens differ from the carcinofetal antigen previously demonstrated on the surface of intestinal cancer cells by xenoantiserum.

Animals↗
PubMed1975

[The technique of quantitative determination of streptokinase in the patient's plasma (author's transl)].

A method of a quantitative determination of plasma streptokinase concentrations in patients undergoing streptokinase infusion is described. The principle of this method is based on the clot lysis time recorded by the thromboelastograph. The test clot constituents were bovine fibrin, bovine plasminogen, human euglobulin, EDTA, human plasma (of unknown streptokinase quantity) and thrombin. As rather high concentrations (fixed excess) of plasminogen (euglobulin) and fibrinogen were present in the test coagulum, no interference with changing plasminogen and fibrinogen levels of the patient's plasma was observed. Furthermore, due to high EDTA concentrations, no interaction with platelet functions and coagulation factors took place. The standard deviation in measuring 2 u streptokinase in 1 ml human plasma was determined as s = +/- 0.19 u/ml, of 5 u streptokinase at s = +/- 0.47 u/ml and of 20 u streptokinase at s = +/- 2.5 u in 1 ml of human plasma. Plasma samples of patients undergoing fibrinolytic treatment were investigated with regard to their streptokinase content. Streptokinase concentration values varied between 0.7 u and 15 u/ml plasma. The average half life of streptokinase in the organism was 18 min. The decay of streptokinase in plasma at different temperatures and over various periods of time was also determined. A considerable loss of streptokinase in the plasma during storage at room temperature could be observed. Therefore, the determination procedures should be carried out without delay.

Animals↗