Detection and identification of antinuclear antibodies (ANA) in a large community hospital.

OBJECTIVE: Antinuclear antibodies (ANA) and their identification are important diagnostic tools in rheumatic diseases. We aimed to determine their prevalence in samples referred for ANA testing and to identify factors predicting more specific reactivities. METHODS: We analyzed the first sample of 6422 consecutive patients for ANA. Positive samples were analyzed by indirect immunofluorescence (IIF) on Crithidia luciliae and by line immunoassay. We used multivariate logistic regression to detect predicting variables. RESULTS: 42.6% of all patients were ANA positive of which 13.0% showed > or = one extractable nuclear antigen (ENA) reactivity with anti-SSA/Ro (5.5%), anti-SSB/La (2.9%), anti-Cenp-B (2.5%) and anti-histones (2.2%) as the most prevalent antibodies. Anti-double-stranded DNA antibodies (dsDNA) were present in 1.0%. The strongest overall predictor was ANA intensity regardless of pattern. Cenp-B however was best predicted by pattern. Anti-dsDNA and anti-histone were more frequent in samples with a homogenous as compared with a speckled pattern. Anti-SSA and anti-SSB were more frequent in females and anti-Sm in patients < or = 30 years. CONCLUSIONS: The best overall predictor of antibodies to ENA or dsDNA is ANA intensity. Anti-Cenp-B is however best predicted by pattern. Samples with low ANA intensity (1+) may not need further testing unless a high clinical suspicion of ANA-associated disease.

Ten years phage-typing of Belgian clinical methicillin-resistant Staphylococcus aureus isolates (1992-2001).

Gradual changes have been observed in the phage-types of methicillin-resistant Staphylococcus aureus (MRSA) isolates from Belgian hospitals. A total of 6551 isolates, collected in 93 Belgian hospitals over 10 years (1992-2001), was examined. A decreasing incidence of the main early Belgian epidemic phage-types ([A], [B], [H]*, Jo*) was observed. Since 1997 and 2000, a new series of phage-types ([Hv]*, [J]*, [O]*), which were likely related to the previous group [H]*, have been noted. The general trends were confirmed in two particular hospitals. Local epidemic and/or endemic phage-types were also encountered.

Infectious gastroenteritis: are they all the same?

Campylobacter jejuni and Salmonella spp are the most frequently cultured micro-organisms in infectious gastroenteritis among patients hospitalized at the departments of gastroenterology and geriatrics. As a whole, the hospitalized patient population with Campylobacter gastroenteritis is a younger one, compared to the Salmonella-infected group. Both pathogens can be associated with a biochemical pancreatitis, which is usually without clinical importance. However, serious complications can occur, with a predominance of visceritis for C. jejuni, and renal function impairment for Salmonella spp. Finally, an asymptomatic carrier state is well known in the Salmonella infection spectrum, whereas C. jejuni might cause a recurrent disease in some patients.

Analysis of fluorouracil in human plasma by combined gas-liquid chromatography mass spectrometry.

Fluorouracil in human plasma of a concentration as low as 2 ng ml-1 can be assayed with the use of gas-liquid chromatography and a multiple ion detector. Fluorouracil is isolated from plasma by anion exchange extraction. The extract is butylated and the derivative obtained extracted into a mixture of cyclohexane + dichloromethane (95:5). An aliquot is submitted to combined gas-liquid chromatography mass spectrometry. The use of chlorouracil or oxygen-18 labelled fluorouracil as internal standard is discussed. Linearity is proven from 100 microgram to 5 ng of fluorouracil per ml plasma. The coefficients of variation are 7.2 and 8.4% for within-run and between-run precision, respectively, at the 50 ng ml-1 level. The biological applicability of our procedure is demonstrated by analysing plasma samples obtained at different time intervals from three patients given 1 g of fluorouracil once intravenously and once orally.

Flame-ionization GLC assay for fluorouracil in plasma of cancer patients.

A rapid and specific flame-ionization GLC method was developed for the determination of plasma fluorouracil. The chloro analog is used as the internal standard. The method involves the isolation of both the drug and the internal standard from plasma on a strong anion-exchange column at pH 10. Elution is performed with acetic acid in methanol. The evaporated eluate is dissolved in tetrahexylammonium hydroxide. An aliquot of the resulting solution is introduced directly into the gas chromatograph, where conversion to the bishexyl derivatives and subsequent separation take place. The extraction recovery from blank plasma, to which fluorouracil was added, was 96.8 +/- 2.4% (SD). Linearity was proven in the range from 0 to 25 micrograms/ml, whereas the detection limit of the method was estimated at about 2 micrograms/ml of plasma. The within-run precision was determined at three different fluorouracil levels. To demonstrate method applicability, plasma samples obtained from cancer patients to whom 1 g of fluorouracil had been administered intravenously were analyzed.

Gas-liquid chromatography of some alkyl derivatives of 5-fluorouracil.

Various procedures for converting 5-fluorouracil into its methyl, butyl and hexyl derivatives are described. Structures were established as the N,N'-dialkyl derivatives using mass spectrometry or combined gas-liquid chromatography-mass spectrometry. The reaction conditions, i.e., the amount of derivatization reagents and reaction time, were optimized. Gas-liquid chromatographic characteristics of the derivatives were investigated on different stationary liquid phases, and 2% or 3% SP-2250, 5% XE-60 and 5% OV-1 were found to be superior. With 5-chlorouracil as the internal standard a linear response for the various derivatives was observed in the microgram range. The applicability of the different dialkyl derivatives in the measurement of 5-fluorouracil in biological materials is discussed.

Application of ion-pair methods of extraction of fluorouracil from aqueous fluids.

The polar molecule, fluorouracil, is a monoanion at pH 10 and may be quantitatively extracted from aqueous solutions with quaternary alkylammonium ions into an organic solvent such as dichloromethane as the ion-pair. Extraction constants of fluorouracil with the tetrapentylammonium ion in dichloromethane or dichloromethane-1-butanol (9:1) and with the tetrahexylammonium ion in dichloromethane were determined. Slope analysis demonstrated that association of the ion components in the aqueous phase occurred as the side reaction. A column ion-pair extraction technique, using tetrapentylammonium as the counterion and dichloromethane as the eluting phase, was developed and allowed quantitative transfer of fluorouracil to the organ solvent. The applicability of this method was shown by determining plasma levels of fluorouracil in cancer patients to whom 1 g of active substance was administered intravenously.