Methods of theophylline assay and therapeutic monitoring of this drug.

The purpose of this article is to review various analytical methods of monitoring plasma theophylline. This article was investigated by the "Drug Commission" of SFBC (Société Française de Biologie Clinique). The primary objective is to provide the "know-how", particular for this analysis, which allows the choice between various analytical methods available: immunochemical or physiochemical ones. The techniques described are not necessarily the best, they are approved and tested methods which are the most frequently used in routine practice. The proposed immunochemical methods are: absorption spectroscopy methods: Enzyme ImmunoAssay (EIA), Enzyme Multiplied ImmunoAssay Technique (EMIT); Reflectance spectroscopy method: Apoenzyme Reactivation Immunoassay System (ARIS); Fluorometry spectroscopy method: Substrate Labeled FluoroImmunoAssay (SLFIA); Fluorometry spectroscopy on solid base; Polarization fluorescence spectroscopy ImmunoAssay (FPIA); Turbidimetric measurements: Particle Enhanced Turbidimetric Inhibition ImmunoAssay (PETINIA); Nephelometric measurement: Nephelometric Inhibition ImmunoAssay (NIIA). And the proposed physicochemical methods are: High Performance Liquid Chromatography (HPLC), Gas Chromatography (GC). The second objective is a review of pharmacological properties of theophylline, necessary for a good understanding of therapeutic drug monitoring: intestinal resorption, distribution, metabolism and elimination, drug interactions, dose/response relationship, physiopathological variations and proposed "predictive" "theophylline test". The authors conclude that because of the multiplicity of methodologies used in theophylline therapeutic monitoring the choice of one of them is not easy. The best way to compare different techniques available would be the use of a "reference material" for theophylline monitoring and a quality control network between different clinical pharmacological laboratories.

Pharmacokinetic and pharmacodynamic comparison of two doses of long acting propranolol (80 and 160 mg) in healthy subjects.

1. The kinetics and dynamics of long acting propranolol 80 mg and 160 mg were examined after single oral doses to 12 healthy volunteers. 2. Long acting propranolol 160 mg produced a twofold increase in mean peak blood propranolol concentration and AUC compared with the lower dose. There was no difference in elimination half-life, bioavailability and mean residence time of propranolol between the two doses. 3. Resting pulse rate was decreased by long acting propranolol 160 mg but not by the lower dose. 4. Both preparations blocked exercise induced tachycardia during the entire observation period of 29 h. Percentage inhibition of exercise tachycardia was significant at all time points but long acting propranolol 160 mg exhibited a greater reduction at 24 h and 29 h. 5. Increase in systolic blood pressure during exercise was inhibited by both preparations during the entire observation period with no differences between them. 6. The doubling of the dose administered was reflected in blood concentrations but not in pharmacodynamic parameters. Few pharmacodynamic differences were found between the two doses.

Evaluation of Roche fructosamine test: use for diabetic patient monitoring.

A fructosamine assay using commercially available reagents on an IL Multistat III centrifugal analyser was evaluated. Within- and between-batch precision were less than 4% (CV). Results were similar using serum or oxalated plasma, but were 5% lower than those using sodium heparinate. We compared serum fructosamine and Hb A1c results in insulin-dependent and non-insulin-dependent diabetics: serum fructosamine correlated with Hb A1c (r = 0.80) and gave at least as good a separation of patients from normal controls as did Hb A1c.

[Measurement of total bile acids. Comparison of different preparations of 3 alpha-hydroxysteroid dehydrogenase]. / Dosage des acides biliaires totaux. Comparaison de différentes préparations de 3 alpha-hydroxystéroïde déshydrogénase.

Oxidation of free and conjugated biliary acids was carried out with 5 different enzymatic preparations of 3 alpha-hydroxysteroid dehydrogenase. The comparison of the catalytic activities obtained, shows the existence of important variations according to the enzymes. Preparations purified by chromatography have a stronger activity toward primary biliary acids than toward secondary biliary acids, while preparations obtained from bacterial mutants have a low activity toward cholic acid and its conjugates.

A simple model relevant to toxoplasmosis applied to epidemiologic results in France.

A simple mathematical model was applied to the results of a seroepidemiologic study of toxoplasmosis carried out in France in 1982-1983. An adequate fitting to the prevalence data observed on 7,605 women of childbearing age was obtained. Thus, the data were used to estimate the seroconversion rate, allowing the approach to and discussion of insights gained from the model, such as the risk of Toxoplasma infection during pregnancy, the age-related expected risks of maternal seroconversion, as well as an overall prediction of the yearly number of congenitally infected infants in the total population. In addition, the high prevalence of congenital toxoplasmosis in France and the excess risk encountered by young migrant women from lower prevalence areas were confirmed by the model. The model might therefore be useful for public health purposes in other countries.

Effects of pregnancy on the inter-individual variations in blood levels of lead, cadmium and mercury.

Blood samples to be analysed for lead, cadmium and mercury were taken from 417 pregnant women not occupationally exposed to these metals. Each subject was paired with a non-pregnant woman of the same age (+/- 2 years), socio-economic status, alcohol and tobacco status. Most of the inter-individual variations observed in earlier studies were confirmed in the control group. Among the pregnant women, however, such variations in blood metal levels appeared to be somewhat different compared to the control women according to the parameters studied: age of the women, alcohol and tobacco consumption. Furthermore, the study of the evolution of blood levels of lead, cadmium and mercury throughout pregnancy revealed a significant decrease in cadmium levels during the first half of pregnancy. A similar tendency was observed for lead but this did not attain statistical significance.

A study of the microheterogeneity of transferrin in cirrhotic patients.

In order to assess the specificity of transferrin molecular changes, we compared concentrations of subfractions and total transferrin in cirrhotic patients, in patients having non-alcoholic hepatitis, in patients with liver cancer, and in controls. The study was carried out in 79 patients divided into four groups: 20 patients with biopsy-proven cirrhosis of alcoholic origin, 20 patients with non-alcoholic hepatitis, 19 patients with liver cancer and 20 controls. Subfractions of serum transferrin were separated by isoelectric focusing followed by direct immunofixation. Fractions pI 5.7 percentages (expressed as percentages of one fraction over total transferrin) were significantly higher in the cirrhotic group than in the control group (p less than 0.01). Fraction pI 5.9 percentages were significantly higher in the cirrhotic group than in the hepatitis or control groups (p less than 0.05), or liver cancer group (p less than 0.01). A quantitative increase of fraction pI 5.7 was found in the cirrhotic patients. However, in this study, this parameter did not discriminate between patients with parenchymal liver diseases of alcoholic or other origin. Therefore, the value of determining fraction pI 5.7 as a marker of chronic alcohol consumption seems questionable. The elevation of fraction pI 5.9 constantly found in the cirrhotic patients could not be explained and needs further investigations.

The combined effect of tobacco and alcohol consumption on the level of lead and cadmium in blood.

This study deals with the person-to-person variation in the levels of lead and cadmium in the blood of 6437 subjects (2883 men and 3554 women). The lead level (Pb-B) is clearly higher in men than in women, and the cadmium level (Cd-B) is a little higher in men than in women. Only the Pb-B varies according to age for both sexes. The results reveal that the consumption of alcohol could play an important part in the variation of lead and cadmium levels in the blood; the consumption of alcohol is associated with an increase in Pb-B but a decrease in Cd-B. These variations involving alcohol consumption remain significant regardless of smoking habits. On the other hand, an increase in Pb-B and Cd-B has been noted among smokers and, to a lesser degree, among former smokers, compared with non-smokers.

Separation of haemoglobins using a monodisperse cation exchanger.

In order to separate haemoglobin variants in one step, a chromatographic method using Mono S (Pharmacia) monodisperse cation exchanger was developed The separation of haemoglobins (A, S, E, D, C and F) on a short analytical column (50 X 5 mm I.D.) was accomplished in 30 min, including the regeneration, using linear buffer gradient elution (lithium chloride in 0.01 M sodium malonate, 0 to 100%). For haemoglobin A, two peaks, probably corresponding to different molecular forms, were found. This systematic double peak affected the recognition and the measurement of haemoglobins. By filling the test-tube with carbon monoxide before injecting the haemolysate, we obtained reproducible results with regard to both retention times and peak shape, and also great stability. The long-term stability and the high speed of the separation seem to be adequate for automation, making the method suitable for routine clinical laboratory-use.

[Undetected cryoglobulinaemia may alter the serum protein results and mask dysglobulinaemia (author's transl)]. / Une cryoglobulinémie non soupçonnée peut fausser les résultats des protides sériques et faire méconnaître une dysglobulinémie.

By reporting a case of massive cryoglobulinaemia where precipitation of the cryoglobulins occurred at 35 degrees C but with no apparent clinical symptoms the authors want to draw attention to the fact that if cryoglobulinaemia remains undetected it may alter the serum protein results and mask dysglobulinaemia. However if protein electrophoresis is carried out at the same time, it is possible to detect a slight abnormality due to cryoglobulin fraction not entirely removed during centrifugation of the blood sample. This finding should incite one to look for cryoglobulins according to the usual procedure (at 37 degrees C) as well as to measure serum proteins on a sample also collected at 37 degrees C. Thus occasionally one happens to detect such dysglobulinaemia and if all results point to a diagnosis of myeloma -- as was the case here -- treatment can then be started early with advantage.

Biochemical problems caused by some cryoglobulins.

An unsuspected cryoglobulinaemia may be responsible for incorrect serum protein results and thus cause dysglobulinaemia to remain undetected. When cryoglobulins precipitate above laboratory temperature, they will be removed with the clot during centrifugation of the blood sample if they have not previously been suspected clinically or biologically. In the case of massive cryoglobulinaemia, one might find normal protein results but such results are incorrect and if only total protein estimation has been requested, dysglobulinaemia can remain undetected. However, if electrophoresis can also been carried out, a slight abnormality of the gamma globulin fraction might be observed and this ought to incite one to look for cryoglobulin by the usual method (i.e. at 37 degrees C), even in the absence of clinical evidence.