PubMed Health⌕ Search

Biomedical subjects

T Nicot

Publications and source records attributed to T Nicot.

12 recordsLinked to original sources
PubMed1999

Automated column-switching high-performance liquid chromatography method for the determination of 1-hydroxypyrene in human urine.

An on-line sample treatment method to determine 1-hydroxypyrene (1-OHP), a metabolite of polycyclic aromatic hydrocarbons (PAHs), in human urine has been developed. The hydrolysed biological fluid was directly injected into the chromatographic system after only centrifugation. A miniature precolumn loop packed with a preparative phase and coupled on-line to a liquid chromatographic (LC) system was used for analyte enrichment. The analytes were non-selectively desorbed with the LC eluent and cleaned by means of a column-switching procedure comprising two purification columns and an analytical column. Pre-treatment and analysis were performed within 2 and 20 min, respectively. Average 1-OHP recovery reached 99% in the 1-25 microg/l range of urine, and the quantitation limit was 20 ng/l for 100 microl of injected sample. A comparison with a more time-consuming off-line method was performed by analysing 120 urine samples of PAH-exposed and expected unexposed workers; the statistical treatment indicated that both methods are in agreement.

Automation↗
PubMed1998

Automated column-switching high-performance liquid chromatography for the determination of aflatoxin M1.

An extractionless method for determining aflatoxin M1 (AFM1), a major metabolite of aflatoxin B1 (AFB1), in human urine was developed. The biological fluid is injected directly into the chromatographic system after simple dilution and centrifugation. A pre-column, packed with a cation-exchange phase and coupled on-line to a column-switching liquid chromatography (LC) system, is used for sample pre-treatment and concentration. The analytes are non-selectively desorbed with the LC eluent and cleaned by means of a column-switching procedure. Pre-treatment and analysis were performed within 40 min. Average AFMI recovery reached 97% in the 10-100 ng/l range of urine. The detection limit of AFM1 in urine and milk was 2.5 ng/l for 1 ml of injected sample. A comparison with an immunoaffinity column clean-up and LC method was performed. The method was applied to determine AFM1 in the urine of AFB1 gavaged rats, and in the urine of both potentially exposed and supposedly unexposed workers. The method was also extended to milk.

Aflatoxin M1↗
PubMed1997

[Primary cytomegalovirus infection and pregnant women: epidemiological study on 1100 women at Limoges].

During 13 months, 1101 women attending for antenatal care at Limoges University Hospital were prospectively studied to determine the prevalence of Cytomegalovirus (CMV) antibodies: 47.9% of these women were CMV seropositive. Ethnic group was strongly associated with CMV status: 42.6% of metropolitan and 94.5% of immigrant women were seropositive. Seropositivity was associated with increasing parity and older age. The risk of a susceptible woman to acquire CMV infection during pregnancy is 0.7%. Among the 4 seroconversions, 3 children were infected, with developmentally and neurologically normal status in one case, moderate ear damage in an other case and a disseminated infection in the third case requiring a provoked abortion.

Adult↗
PubMed1996

Capillary electrophoresis and supercritical chromatography, complementary and alternative techniques for the determination of urinary metabolites of styrene.

Two analytical methods without an extraction step were developed using capillary electrophoresis and supercritical fluid chromatography in order to determine phenylglyoxylic (PGA) and mandelic (MA) acids in urine, with minimum treatment and manipulation of biological samples. The urine was diluted ten-fold in acetonitrile and directly injected into the analytical systems after centrifugation. Analysis was performed by capillary electrophoresis on alkyl bonded phase capillary columns with sodium formiate (4 x 10(-2) M)-isopropanol (9:1, v/v) as a buffer, and by supercritical fluid chromatography on a Diol bonded phase silica column with ethanol-water-methanesulphonic acid (97.5:2.4:0.1, v/v) as coeluent of CO2. Detection of PGA and MA was performed by ultraviolet detection at 255 and 210 nm, respectively. The methods are in agreement, and are easily able to detect 5 mg/g creatinine for PGA, and 15 mg/g creatinine for MA, which are one twentieth of the lowest biological exposure index values.

Air Pollutants, Occupational↗
PubMed1996

[New hepatitis viruses "E, GB, etc."].

Some cases of hepatitis were non A, non B, non C, non D. Hepatitis E virus (Calicivirus) transmission is fecal-oral similar to that of the hepatitis A virus. Viral hepatitis E is endemic and frequently epidemic in many developing countries, but exceptionally observed in France. A high mortality rate was observed in pregnant women. Recently, ELISA assays for IgM anti-HCV are available. Many hepatitis cases (acute and chronic) are not caused by known viruses (non A-non E). Four Flavivirus like have recently been cloned from infectious tamarin serum, derived from human viral hepatitis. Three viruses GB Virus A (GBV-A), GB Virus B (GBV-B) and GB Virus C (GBV-C) were identified. The GB viruses and HG Virus are not genotypes of hepatitis C Virus (HCV) and perhaps that GBV-A/GBV-C and HGV are closely related. GBV-A could be an indigenous tamarin virus. The new hepatitis (non A-non E) viruses were associated with blood transmission and with chronic diseases. The development of specific diagnostic reagents using polymerase chain reaction (PCR) and ELISA assays are essential to answer many questions on the epidemiology (and the incidence of post-transfusion hepatitis), and the pathogenesis of GBV and HGV viruses.

Enzyme-Linked Immunosorbent Assay↗
PubMed1995

[Serologic and genomic research by PCR of hepatitis C virus in different populations in Lomé (Togo)].

An epidemiological survey carried out on several groups at University Hospital of Lome showed that the prevalence of anti-HCV antibodies is 3.3 % among blood donors, 1.3 % in STD positive subjects and 6.1 % in hospitalized patients. The disparity of the HCV seropositivity rate was not statistically significant among HIV-infected and non-infected subjects (6.9 % vs 3.3 % respectively). The HCV RNA was most frequently recovered from patients, whose serological pattern was confirmed but also from 30 % of subjects, for whom the HCV serology was proved. This shows the limits of serological tests in Africa.

Adolescent↗
PubMed1994

Dietary habits, a non-negligible source of 2-thiothiazolidine-4-carboxylic acid and possible overestimation of carbon disulfide exposure.

2-Thiothiazolidine-4-carboxylic acid (TTCA) is the accepted urinary indicator of occupational exposure to carbon disulfide. This compound was detected in blank urine of individuals unexposed to carbon disulfide during an experimental validation of a new method of determination. Diet was suspected to be the source of TTCA, and particularly the consumption of brassica vegetables. This assumption was confirmed by collection and analysis of urine samples after ingestion of crude cabbage. TTCA was detected at concentrations higher than 2 mg/l in urine, and 3 mg/kg in crude cabbage. The identity of TTCA was confirmed after extraction and separation by capillary electrophoresis, supercritical fluid chromatography, and mass spectrometry. The results show that the diet should be considered as a nonnegligible source of the overestimation of carbon disulfide exposure.

Biomarkers↗
PubMed1993

Automated column-switching high-performance liquid chromatography for the determination of 2-thiothiazolidine-4-carboxylic acid in urine.

2-Thiothiazolidine-4-carboxylic acid (TTCA) is the accepted urinary indicator of occupational exposure to carbon disulfide. An extractionless automated column-switching procedure for the determination of this compound in urine was developed. The biological fluid is directly injected into the chromatographic system after dilution. A clean-up procedure is performed in an anion-exchange pre-column, with aqueous formic acid as eluent, followed by a transfer to a cyan-amino or amino analytical column in order to carry out analysis of TTCA under isocratic elution conditions, with a mixture of acetonitrile, water and formic acid as eluent, combined with ultraviolet detection. The detection limit of the method in urine is estimated to be 0.1 mg/l.

Acetonitriles↗
PubMed1986

Assessment of tail nerve function in rats chronically exposed to vinyltoluene.

In male Sprague-Dawley rats, motor and sensory conduction velocities (MNCV and SNCV) of the tail nerve decreased significantly as a result of oral administration of 400 and 200 mg/kg of 2,5 hexanedione (2,5-HD) once daily, 5 days a week for up to 7 and 15 weeks, respectively; and of whole-body exposure to 300 ppm of vinyltoluene for 6 h daily, 5 days a week for up to 21 weeks. Exposure to 100 ppm of vinyltoluene did not cause any significant impairment of tail nerve function throughout the 21-week exposure period. Significant changes in MNCV and SNCV were consistently observed from weeks 4 and 2, respectively, in 2,5-HD-treated rats. Changes resulting from exposure to 300 ppm of vinyltoluene were reported intermittently from week 15. Significant linear relationships were established between the length of treatment with 2,5-HD, length of exposure to 300 ppm of vinyltoluene, and the extent of impairment of tail nerve function. Structural damage to the sciatic nerves was only seen in 2,5-HD-treated rats. It is concluded that vinyltoluene can be regarded as an airborne chemical which leads to the development of a borderline experimental neuropathy at a level of 300 ppm.

Action Potentials↗