[The metallic profile: a new biological concept]. / Une nouvelle approche biologique: le profil métallique.

Considerable advances have been made in metals and metalloids analysis over the past decade. This analysis is a basic stage in deficiency or toxicity assessment. A recently introduced technique, inductively coupled plasma mass spectrometry (ICP-MS) is progressively replacing atomic absorption. This analysis permits multi-elementary determinations, many ten or so elements, among periodic classification, with an optimal gain in sensitivity in many biological matrices: i.e. whole blood, plasma, urine, hair, nail, and biopsy samples. Moreover, this method allows semi-quantitative determination with an additional thirty supplementary elements, which enables the toxicologist to sufficiently estimate the toxic levels and metal exposure. The authors demonstrate that the ICP-MS could be very useful for a wide range of clinical applications. Furthermore, this procedure offers new exploration possibilities in various fields such as clinical chemistry but also clinical toxicology, forensic toxicology as well as workplace testing or environmental exposure and permits epidemiologic studies. This analytical method in fact also provides a new biologic approach. To our knowledge we are the first to propose the metallic profile.

[Inductively coupled plasma: a promising new tool with application in human toxicology and public health]. / La torche a plasma: un nouvel equipement aux applications prometteuses au service de la toxicologie humaine et de la santé publique.

The authors describe the use of inductively coupled plasma to detect 32 metals and metalloids in blood, urine, hair and nails. They also report the first case of gadolinium overdose documented by blood analysis with this method Metal speciation, a new approach developed in our laboratory, can distinguish between toxic and non toxic metals.

Metal and metalloid multi-elementary ICP-MS validation in whole blood, plasma, urine and hair. Reference values.

Four multi-elementary metal and metalloid quantification methods using inductively coupled plasma mass spectrometry (ICP-MS) were developed and validated in human whole blood, plasma, urine and hair by means of a single preparation procedure for each sample. The ICP-MS measurements were performed using a Thermo Elemental X7CCT series and PlasmaLab software without a dynamic reaction cell. With this procedure 27-32 elements can be simultaneously quantified in biological matrices: Li, Be, B, Al, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Rb, Sr, Mo, Pd, Ag, Cd, Sn, Sb, Te, Ba, W, Pt, Hg, Tl, Pb, Bi, U. Whole blood, plasma and urine samples (0.4 ml each) were diluted with purified water, acid, triton X100 and butanol. Rhodium was used as internal standard. The urine sample results were corrected for enzymatic creatinine determination. Twenty-five milligrams hair samples were acid mineralized after a decontamination procedure and diluted as previously described for biological fluids. To be validated, each element had to show linearity with a correlation coefficient higher than 0.99. The intra-assay and inter-assay inaccuracy, measured as the variation coefficient, were below 5 and 10% respectively. Global performance was assessed by a quality control program. Our laboratory is a registered participant of the Institut National de Santé Publique du Québec (Sainte-Foy, Canada) inter-laboratory comparison program for whole blood, urine, and beard hair of non-occupationally exposed individuals spiked with selected elements. In our study multi-element metal and metalloid analysis was assessed for 27 elements in whole blood, 27 elements in plasma, 30 elements in urine and 32 elements in hair, from 0 to 25, or 250 to 1000 ng/ml, depending on the element. Quantification limits ranged from 0.002 ng/ml (U) to 8.1 ng/ml (Al) for whole blood, from 0.002 ng/ml (U) to 7.7 ng/ml (Al) for plasma, from 0.001 ng/ml (U) to 2.2 ng/ml (Se) for urine, and from 0.2 pg/mg (Tl) to 0.5 ng/mg (B) for hair. Normal values were determined in whole blood (n=100), plasma (n=100), urine (n=100), and hair (n=45) of healthy volunteers, leading to approximately 10,000 analyses. All results are presented and discussed. Clinical toxicology and forensic toxicology applications are also reported. ICP-MS has made significant advances in the field of clinical biology, particularly in toxicological analysis. This is due to the use of extremely effective equipment that permits better clinical and forensic toxicological analysis of metal and metalloid status of each individual patient.

Glycated hemoglobin: a useful post-mortem reference marker in determining diabetes.

Glycated hemoglobin (HbA(1c)) has been demonstrated to be a useful marker for long-term glucose control in diabetes. This parameter characterizes each non-enzymatic fixation of glucose on hemoglobin. It is a useful test in addition to periodic glycemia controls since it reflects the mean glycemia of the past 60 days. We studied the conservation of HbA(1c) at 4 degrees C as a function of time with different anti-coagulants and preservatives (3, 6 months, 1 year). A total of 106 tests were performed using the high performance liquid chromatography (HPLC) method dedicated to the semi-automatic analysis of HbA(1c) (Bio-Rad) and we applied the method in forensic cases. Conservation at 4 degrees C was good for as long as 3 months in blood samples collected with fluoride and 6 months in samples collected in a dry or in a heparinized tube. In non-diabetic subjects, HbA(1c) reference values obtained from forensic samples were identical to those of living controls (3.5-6.25% of total hemoglobin). All positive HbA(1c) results were confirmed by a medical evaluation. This method was successfully applied to five forensic cases. In cases of increased acetonemia, acetone or isopropanol are easily measured. However, in some unexplained post-mortem circumstances, increased HbA(1c) permits to differentiate alcoholic or starvation ketoacidosis from the diabetic cases. Glycated hemoglobin should, therefore, be considered the forensic marker of choice in the post-mortem diagnosis of a diabetic disorder and demonstrates its usefulness in post-mortem validation.

Silent hypersensitivity to Escherichia coli asparaginase in children with acute lymphoblastic leukemia.

This prospective study aimed to assess the incidence of silent hypersensitivity to Escherichia coli asparaginase in the treatment of acute lymphoblastic leukemia (ALL). Thirty-three children with newly diagnosed ALL were included in the study and treated according to the FRALLE 2000 protocol. The 'A group' (n = 18) differed from the 'B-T group' (n = 15) by a less intensive chemotherapy, the absence of concurrent prednisone therapy, and different asparaginase administration modalities during the second intensification. Asparagine, asparaginase activity, and anti-asparaginase antibodies were measured in each phase before the next injection of asparaginase. Eighteen percent of children presented a silent hypersensitivity. Most of them were in the 'B-T group' (p = 0.07), and maintained low antibody titers throughout the treatment. Clinical hypersensitivity was statistically more frequent in group A (p = 0.002), and allergy occurred mainly during the second intensification when antibody concentrations were significantly increased. We did not find any significant difference between asparaginase activity or asparagine depletion between the silent hypersensitivity and clinical allergy groups. In all, the results of this study suggest that chemotherapy and corticosteroid therapy associated with asparaginase treatment can lower antibody production and contribute to maintaining a silent hypersensitivity state.

Lewis-Sumner syndrome and Tangier disease.

OBJECTIVE: To report unusual electrophysiologic data in a patient with Tangier disease in an effort to better understand the pathophysiologic features of the peripheral nerve lesions in this disease. DESIGN: Case report. PATIENT: A 15-year-old girl had subacute onset of asymmetric neuropathy with persistent conduction block, resembling Lewis-Sumner syndrome. MAIN OUTCOME MEASURES: Electrophysiologic data in Tangier disease. RESULTS: After initially unsuccessful treatment with intravenously administered immunoglobulins, the finding of an abnormal lipid profile led to the diagnosis of Tangier disease due to the R587W mutation in the adenotriphosphate-binding cassette transporter-1 gene (ABCA1) (OMIM 9q22-q31). CONCLUSIONS: Conduction block, which is the electrophysiologic hallmark of focal demyelination, can be present in Tangier disease. It could be induced by focal nerve ischemia or by preferential lipid deposition in the paranodal regions of myelinated Schwann cells. The presence of a conduction block in Tangier disease may lead to a misdiagnosis of dysimmune neuropathy.