Biomedical subjects
Publications and source records attributed to M Manchon.
An automated immunoassay for Digoxin in serum using dry-reagent strips (Stratus Dade) was evaluated, and compared with two others immunoassays (TDX Abbott and ACA Du Pont). Precision, sensitivity and specificity were satisfying, as well as correlation study, but discrepancies observed for some sera proved that these techniques still pose serious problems of specificity or of standardisation.
Rhabdomyolysis following the knee-chest position was studied in 15 patients scheduled for surgery for spondylolisthesis. A comparison was made between 11 patients scheduled for orthopaedic surgery: ligamentoplasty (6 patients), total hip prosthesis (5 patients) and 11 patients scheduled for long oral surgery. The measurements carried out were blood CPK before surgery, 4, 8, 12 and 24 h after the beginning of surgery, and at days 2, 3 and 4. Blood and urinary myoglobin were measured at days 1, 2, 3 and 4 after surgery. The results were tested with the Mann and Whitney test. There was no statistical change in CPK and myoglobin in the test population. Following the knee-chest position, there was a statistical increase of CPK in all patients, with great individual variations. Myoglobinaemia and myoglobinuria were observed in six patients, these not being correlated with the variations of CPK. Nevertheless, the maximal increase of CPK and myoglobin was seen in one patient, without any modification of diuresis but with an increase of creatininaemia at 220 mmol X l-1. In this series, rhabdomyolysis was real. CPK was not a good index of the release of haematic pigments, the only dangerous ones. A qualitative search for myoglobinuria is suggested, this being followed, or not, by alkalization to prevent acute renal failure.
The characteristics of benzodiazepine binding sites (distribution, number, affinity) were defined on frozen sections of suicide's hippocampus (death by hanging) labeled with 3H flunitrazepam and compared to data previously obtained on control brains. The study was carried out qualitatively by autoradiography (distribution) and quantitatively by a biochemical technique (number and affinity). As a whole, the characteristics of BZD binding sites were not modified in relation to controls, except for a very slight decrease in affinity of subtype I.
Benzodiazepine-binding sites were studied on frozen sections of 5 human hippocampi, using autoradiographic and biochemical techniques. The affinity, density, distribution and heterogeneity (two types) of sites were investigated using [3H]flunitrazepam as a ligand, clonazepam or C1 218872 as displacing agents. The autoradiographic images evidence a differential distribution of the binding sites in the histologic layers of the hippocampus. Subtypes I and II coexist in the same proportion in the three layers exhibiting the highest densities of binding sites (stratum granulosum and pyramidale, deep layer of stratum radiatum). The Kd, Bmax and Ki values found here are analogous to those described in animal studies, but the anatomical distribution of the sites in human hippocampus seems to differ slightly from that previously described in that of the rat.
A new reactive strip was used in a hospital admission unit, to detect amylasuria in the urine of 76 patients consulting for abdominal pain (population A) and of 68 unselected patients (population B). Detection on admission by this method was concordant with subsequent laboratory detection in 93% of the cases. The fast test was positive for amylasuria in 17 patients: 13 (17.1%) in population A and 4 (5.9%) in population B. The 8 patients recorded as "+" had moderate amylasuria with multiple but ill-defined symptoms mostly abdominal. The 9 patients recorded as "++" had marked amylasuria highly suggestive of an abdominal disease, including 4 cases of chronic pancreatitis.
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The EMIT-TOX Enzyme Immunoassay for benzodiazepines was evaluated. Reproducibility, linearity, accuracy, sensitivity, and interferences were tested and found to be in good agreement with the manufacturer's specifications. Furthermore, the reactivity of 15 benzodiazepines were studied. According their differential reactivity, the 15 benzodiazepines can be classified into three groups: good reactivity similar to diazepam (potassium clorazepate, prazepam, estazolam, medazepam, flunitrazepam, nitrazepam); medium reactivity (clobazam, clonazepam, bromazepam, chlordiazepoxide, triazolam); and low reactivity (oxazepam, ethyl loflazepate, lorazepam). A possible structure/reactivity relationship is discussed. It is concluded that this kit is well adapted for the rapid detection of most benzodiazepines, but in no way can the EMIT technique permit quantitative results without clinical information.
The biochemical changes in blood during intraperitoneal chemohyperthermia (IPCH) were examined by carrying out complete assessments before and after the operation. These assessments were made up of 23 parameters: Na, K, Cl, CO2, urea, creatinine, proteins, glucose, calcium, phosphates, magnesium, bilirubin, uric acid, lactic acid, CRP, ASAT, ALAT, CK, LDH, gamma-GT, ALP, lipase, and amylase. Only 5 of these parameters showed significant changes: proteins, urea, ALP, gamma-GT, lactic acid. The protein and urea levels decreased due to hemodilution induced by the perfusion of fluids. ALP and gamma-GT levels decreased, possibly due to localized inhibition of secretion. Lactic acid levels increased due to the movement of lactates from the heated fluid into the blood. The study of biochemical changes within the heated fluids was made using the following parameters: CA 125, CA 19-9, CEA, ASAT, ALAT, CK, LDH, gamma-GT, ALP, lipase, uric acid, phosphates, proteins, Na, K, Cl, urea, creatinine, and magnesium. Between the beginning and the end of IPCH, significant increases were found in the levels of CA 125 (+173%), proteins (+190%), ASAT (+130%), LDH (+103%), K+ (+232%), PO4 (+134%), and uric acid (+99%). These increases indicate the existence of a significant degree of cellular lysis.
Tolerance of intraperitoneal chemohyperthermia (IPCH) with mitomycin C (2 mg/kg) by irrigation of the peritoneal cavity via a closed circuit system was evaluated in Beagle dogs for possible use in the management of human peritoneal carcinomatosis. Of dogs, 24 underwent three digestive anastomoses each. They were randomized into three groups: control (n = 6), intraperitoneal hyperthermia (n = 8) and IPCH (n = 10). Peritoneal temperatures were maintained between 41-43 degrees C for 60 min. Tolerance was evaluated through clinical follow-up, biological samples (serum electrolytes, blood counts and serum enzymes), histological examinations and post-mortem macro- and microscopic controls of anastomosis. Mortality and morbidity rates were not different in the three groups. No anastomotic leakage occurred. Evidence of biological toxicity was minimal. Histological examinations showed no definitive tissue damage. IPCH appears to be a safe and reliable device in dogs. Plans to combine IPCH with MMC in surgical resection of patients with peritoneal carcinomatosis are underway.
Emergency analysis in toxicology is a difficult exercise. It involves in diagnosis, prognosis and the treatment of intoxication. Several methods exist in emergency screening. We have distinguished three large groups. Based on specificity: screening methods of medicament family (chemical methods and immunoassays) with benzodiazepines, tricyclic antidepressants, barbiturates and phenothiazines; complementary screening methods (thin layer chromatography and high pressure liquid chromatography) for a wider screening and finally quantitative methods (enzymatic, immunoassay, spectrometry and chromatography) specific to a molecule. The first group allows a rapid qualitative research according to medicament class but lacks specificity. The second group represented by the Remedi system, offers a larger screening of molecules but is more expensive and cannot detect classic molecules. The third group allows a precise dosage but is restricted to one molecule. We need one or the other of methods following clinical context and the type of molecule. In our laboratory, we have eliminated barbiturates and benzodiazepines research. We search only tricyclic antidepressants, salicylates and paracetamol. The Remedi system acts as a complement. It is essential to have a good knowledge of the limits and specificity of each method in order to allow the clinician to see the interpretation of the given result. The execution period and the quality of analytical result depend on dialogue between analyst and clinician before and after analysis.
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The aim of this study was to evaluate and to validate an enzyme immunoassay in homogeneous phase for netilmicin and amikacin, adapted on the Dimension RXL HM (Dade Behring) machine. The results were compared with those obtained with automated polarization of fluorescence immunoassay using TDx FLx (Abbott). The protocol of the study and the analytical criteria were inspired by the protocol Valtec version 2002 recommended by the French Society of Clinical Biology (SFBC). The validation of this technique as adapted to the Dimension RXL HM has allowed its use for routine dosage adjustment of amikacin and netilmicin. The practicability is however the weak point of the adaptation of these techniques, even limiting as for their implementation.
Biochemical and pharmacological tests usually prescribed in casualty department were reviewed taking into account their physiological significance and predictive value : ions, total proteins, carbohydrate and nitrogenous metabolites, enzymes, tissue markers, pharmacological drugs. Few blood components were kept with the first intention, ideally with a turn around time below one hour: sodium, potassium, chloride, bicarbonate, total proteins, pCO2 and pO2, creatinine, glucose, ketone compounds, calcium, bilirubin, transaminases, lipase, C-reactive protein, myoglobin, troponin, chorionic gonadotropin hormone. Those tests do not have to be systematically performed but prescribed only after the evaluation of pre-test probabilities by the clinician.
Serum digoxin measurement is often performed in medical laboratories. A professional association specialized in quality control, based in Lyon, has been organizing punctual controls of medication measurement for the past ten years. The results are analysed in term of intra and inter-technique precision, difference between methods and specificity in regard to endogenous or exogenous interfering substances. Methods have changed with a quasi disappearance of the methods used ten years ago (FPIA, EMIT) and introduction of new technologies on recent immunoanalysis automates. The results observed with the different instruments are similar. Reproductibility has not changed over ten years. Some difficulties remain in the measurement of low concentrations of digoxin. Many substances interfere in digoxin measurement : digoxigenine (inactive metabolite), endogenous digoxin-like immunoreactive factors, spironolacton, antidigoxin antibodies used for treatment of digitalic intoxications. These interferences depend on the method which is used, but it is essential to know them in order to interpret the results correctly.
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BNP and NT-proBNP are both well established as diagnostic and prognostic markers for congestive heart failure (CHF). However it remains for the biologist to choose between these two biomarkers depending on his equipment availability. The aim of this study was to compare results obtained with the Biosite Triage BNP assay and the Dade Behring NT-proBNP assay with regards to the clinical status. One hundred twelve patients (average age 76 +/- 13 years) with acute dyspnea were including and stratified by diagnosis at presentation into 3 groups: patients without acute CHF (group I, n=50), patients with non-cardiac dyspnea and CHF history (group II, n=22) and patients with acute CHF (group III, n=40). Levels of both BNP and NT-proBNP were higher among patients with cardiac dyspnea (group III) than among patients with a non-cardiac dyspnea (BNP=740 pg/mL versus 84 pg/mL; p<0.001 / NT-proBNP=7.502 pg/mL versus 499 pg/mL; p<0.001). ROC analysis for BNP or NT-proBNP were not statistically different in patients with acute CHF (group III) compared with patients with a non-cardiac dyspnea (group I + II) (AUC=0.927 versus AUC=0.930, p=0.90). Neither there was a difference between ROC analysis for BNP or NT-proBNP in patients with cardiac dyspnea (group III) compared to patients with a non cardiac dyspnea (group I) (AUC=0.981 versus AUC=0.975, p=0.76). Measurement of BNP or NT-proBNP is of identical interest for the diagnosis of acute CHF in acute dyspnea. The BNP Biosite assay was faster because analysis is performed on whole blood. With regards to analytical performance, the NT-proBNP Dade Behring assay had a higher accuracy and is highly recommended for the follow-up of CHF treatment.
The treatment with methotrexate at high doses is responsible of many side effects. It's necessary to evaluate serum methotrexate rate to monitor the administration of the methotrexate antagonist, the folinic acid. The aim of this study is to validate the determination of methotrexate in plasma using the automate Xpand Dimension (Dade Behring). Assay results were linearly related to the concentration for the wide range which was examinated (0.15 - 1.4 micromol/L). We report the precision, accuracy, linearity, sensitivity of this assay. The CV was less than 10%. We present the results of correlations with Aca (Dade Behring) and Cobas Mira (Roche). The reagent cartridge in the instrument and the calibration are stable during 28 days.