L-Tryptophan-Associated Eosinophilia-Myalgia Syndrome: Perspective of a New Illness

Proteomics of toxic oil syndrome in humans: Phenotype distribution in a population of patients

OBJECTIVES

Toxic oil syndrome (TOS) is a disease that appeared in Spain in 1981. Epidemiological work traced the origin to the ingestion of aniline-adulterated rapeseed oil, fraudulently marketed and sold as edible oil. It affected more than 20,000 people with over 400 deaths in the first 2 years. In 2001 evidence was presented that genetic factors could play a role in the susceptibility of individuals to the disease. Thus, a prospective study on the differences in gene expression in sera between control versus TOS-affected populations, both originally exposed to the toxic oil, was undertaken in our laboratory.

METHODS

Differential protein expression was analyzed by two-dimensional electrophoresis (2-DE). Problems related with serum analysis by 2-DE were addressed to improve protein detection in the gel images. Three new commercial systems for albumin depletion were tested to optimize the detection of minor proteins. The use of nonionic reductants or the presence of thiourea in the gels, were also tested.

RESULTS

From the resulting optimized images, a group of 329 major gel spots was located, matched and compared with serum samples. Thirty-five of these protein spots were found to be under- or over-expressed in TOS patients (threefold increase or decrease). Proteins in these spots were identified by matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) peptide map fingerprinting and database search. Several haptoglobin (Hp) isoforms were found to be differentially expressed, showing expression phenotypes that could be related with TOS. Resolution of the homologous α-1s and α-1f chains, with a mass difference of only 0.043Da, was obtained after guanidation of the protein with O-methylisourea. We applied this procedure to the study of the distribution of the Hp alleles HP(2), HP(1s) and HP(1f) in control versus TOS-affected populations. The MALDI-TOF proteotyping method was validated by a parallel analysis of the serum samples by 2-DE.

CONCLUSIONS

Data obtained from 54 TOS cases and 48 controls indicate significant differences in the distribution of Hp phenotypes in the two populations. Haptoglobin phenotypes have been reported to have biological and clinical consequences and have been described as risk factors for several diseases. Consequently, it was concluded that haptoglobin polymorphism could play a role in TOS.

Automated strong cation exchange extraction of fatty acid esters of 3-(N-phenylamino)-1,2-propanediol from oil samples for routine quantification by HPLC-APCI/MS/MS

Fatty acid esters of 3-(N-phenylamino)-1,2-propanediol are currently considered the best chemical markers of toxic oils related to the Spanish toxic oil syndrome. Recent research in this area has undertaken the exhaustive and quantitative characterization of these compounds in oils collected during the epidemic outbreak. Current methods developed in this laboratory are based on solid phase extraction (SPE) using SCX cartridges followed by HPLC-APCI/MS/MS quantification. To circumvent the long and tedious extraction procedure, the SPE protocol was adapted for automatic extraction and the problems derived from the use of the immiscible solvents required for the SCX extraction were solved. Linearity of the analytical method was found in the same range as for the manual method. Extraction recoveries were 87 and 75% for 2-hydroxy-3-(N-phenylamino)propyl linoleate and 2-(linoleyloxy)-3-(N-phenylamino)propyl linoleate, respectively, and the corresponding coefficients of variation were approximately 1%, greatly improving reproducibility over manual procedures.

Chronicity of the eosinophilia-myalgia syndrome. A reassessment after three years

OBJECTIVE

To define the natural history and outcome of eosinophilia-myalgia syndrome (EMS) among a cohort of patients followed up at one center since the onset of their disease.

METHODS

Fifty-seven patients with well-characterized EMS were evaluated prospectively at a university hospital for 21-64 months (mean 36 months).

RESULTS

Eighty-eight percent of the patients continue to have symptomatic disease with > 3 clinical manifestations. Fatigue (91%), muscle cramping (75%), myalgia (70%), paresthesias with objectively demonstrated hypesthesias (62%), articular symptoms (54%), scleroderma-like skin changes (44%), and proximal muscle weakness (40%) are the most common features of chronic EMS. New findings identified among this cohort include cognitive symptoms in 86% of the study group, tremor, and myoclonus.

CONCLUSION

The recognition of new manifestations in EMS and ongoing clinical disease in 88% of patients highlights the chronic nature of this disorder. Continued prospective followup of a large patient base is warranted to further define the natural history of this newly recognized illness.