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Biomedical subjects

G Siest

Publications and source records attributed to G Siest.

At least 397 records · Page 22Linked to original sources
PubMed1976

Quantitative determination of granulocytic amino acids in healthy men and women.

The concentration of the amino acids has been determined in granulocytes from healthy men and women by chromatographic analysis on ion-exchanging resins. Except taurine, ornithine and aspartic acid, the concentrations of all the amino acids are greater in the cells isolated from women. The most variable amino acids are alanine, valine, metionine, isoleucine, leucine, tyrosine, phenylalanine, lysine and histidine. Taurine represents 50% of the pool determined from men, whereas for women it represents only 25%.

Adult↗
PubMed1976

Ornithine carbamoyl transferase activity. Use of a bovine liver extract in quality control.

To obtain a pure ornithine carbamoyltransferase for quality control in clinical chemistry, the authors compared human plasma and bovine liver ornithine carbamoyltransferase. The data show that the KM of both enzymes are similar (respectively 1.03 and 1.33 mmol when ornithine is used as substrate; 1.02 and 1.06 mmol with carbamyl phosphate). The following properties are shown to be equivalent: linearity of the enzymatic reaction, inhibition by higher substrate concentrations, and temperature denaturation. The similarities between the two enzymes indicate that bovine liver ornithine carbamoyltransferase can be used in clinical chemistry quality control.

Animals↗
PubMed1976

Continuous in vivo measurement of creatine kinase variations in man during an exercise.

In order to obtain information concerning the CPK turnover during exercise, we have elaborated a technique to measure its activity continuously in vivo. A colorimetric method has been adapted to total blood. CPK was measured continuously in 5 physically fit athletes exercised on an ergometric bicycle for 30 min. There was practically no increase in enzymatic activity. The starting level was very high, corresponding perhaps to a "permanent state of enzyme release"; the exercise was not hard enough because of the fitness of the athletes or the maximal increase did not occur immediately after the exercise.

Autoanalysis↗
PubMed1976

[Comparison of values, obtained on heparinised serum or plasma, for common biochemical examinations].

The biologist may prefer to use plasma rather than serum to facilitate sampling procedures in his laboratory. It is important to know whether or not the patients' results will be affected by this change. In daily practice, there is no difference to speak of between plasma and serum for bilirubin, calcium, potassium, creatinin, urea, cholesterol, sodium, uric acid, triglycerid and iron. There are, however, differences for total proteins, phosphates and glucose.

Blood Chemical Analysis↗
PubMed1976

Comparison of procedures for extracting free amino acids from polymorphonuclear lekocytes.

We studies five methods for extracting amino acids from human polymorphonuclear leukocytes. Both the use of cell lysis and of a deproteinizing agent interfere with quantitative determination of the amino acids, basic amino acids being the most sensitive to the extraction procedure. Among the methods used, disruption of the cells by freezing-thawing is the best method for extracting all the amino acids. Taurine is the only amino acid extracted in the same amount by all the methods studied, and it represents half of the intracellular pool.

Adult↗
PubMed1975

Amino acid analysis by ion-exchange chromatography using a lithium elution gradient. Influence of methanol concentration and sample pH.

The separation of amino acids has been achieved on a short column of Chromo-Beads C2 resin, with a lithium gradient-elution system. The analysis took 8 h. The separation of asparagine and glutamine from glutamic acid was highly dependent on the sample pH and on the methanol concentration in the first buffer of the gradient. The method has been applied to analysis of human plasma and granulocytes for amino acids.

Amino Acids↗
PubMed1975

[Reference values in biology. Use and special value in preventive medicine].

The idea of reference values should replace in biology, the idea of normal or abnormal values. In fact, progress in physiopathology and laboratory techniques has demonstrated the difficulty of fine interpretation of laboratory examinations. It is first necessary to understand factors of variation due to sampling, then the techniques of analysis themselves. Then, the importance of variations within and between individuals for each laboratory examination. Among the most important factors, we may quote age, sex, drugs, exercise, etc. These various possibilities of interference may be classified in order to remember only those which may falsify reference values, i.e. the values used for clinical interpretation. Thus, these factors are of greater importance in preventive medicine where finer and earlier variations may be observed. The best reference is that of the individual himself, if laboratory examinations are to be used profitably both in preventive and curative medicine. It would be necessary to draw up, for each subject, reference values during a period of good health between the ages of 18 and 25.

Adult↗
PubMed1975

Method for diphenylhydantoin and phenobarbital assay by gas chromatography.

A rapid and easy method for determination of diphenylhydantoin and phenobarbital in plasma by gas liquid chromatography which provides monitoring of epileptic patients therapy is described. These drugs are extracted from plasma by partitioning between cholroform and buffered aqueous phase. The final extract is evaporated to dryness and the residue dissolved in an internal standard (methaqualone) solution. An amount of the final extract is injected tnto OV1 3% column at 230degreeC without previous derivative formation. The results are compared to those obtained by thin layer chromatography followed by colorimetry.

Buffers↗
PubMed1975

Aspartate aminotransferase and alanine aminotransferase activities in plasma: statistical distributions, individual variations, and reference values.

The determination of frequency value (percentile limits) and the classification of the different variation factors allow us to define more and more homogeneous subpopulations as we use these factors for sorting. Using as our study population those persons coming to the Centre for Preventive Medicine, we were able to: (a) Describe and measure the significance and importance of physiological variations or of variations attributed to age--the latter largely related only to excessive weight, which it seems to us is often the case. (b) Establish a classification for variation factors; the recapitulatory table should be useful to clinical chemists in helping physicians interpret a laboratory test result that falls within the zone of incertitude. (c) Suggest a preliminary group of reference values for healthy subjects, to be used in interpreting a laboratory test in this way.

Adolescent↗
PubMed1975

[Enzyme and protein release from human granulocytes: effect of ATP].

The authors study the proteins and enzymes release of resting and phagocytosing human leukocytes suspended in Krebs-Ringer-Phosphate milieu containing or not glucose. They measure the metabolic level and the percentage of enzymes release and show the influence of ATP on this phenomenon. These results are in favour of a direct action of ATP on the cellular membrane.

Adenosine Triphosphate↗
PubMed1975

Colorimetric measurement of ornithine carbamoyl transferase activity in plasma, and results for a supposedly healthy population.

Determination of ornithine carbamoyl transferase (EC 2.1.3.3) activity in plasma is important for detection of liver diseases. The assay established in this paper has been made optimum. A blank is needed containing both substrates, carbamoyl phosphate and ornithine. We used a new colorimetric assay, based on a complex with a phosphoferric-antipyrine reagent and diacetyl monoxime, to measure the citrulline formed. The highly sensitive assay permits low activities to be determined accurately. Values for blood plasma from 425 supposedly healthy people, varied from 0 to 16 U/liter (95th percentile), and 27% of this population showed an activity of less than 2 mumol of citrulline formed per minute per liter, 2 U/liter being the limit of the method's sensitivity.

Colorimetry↗