Comparison of the Q-fever complement fixation test and two commercial enzyme-linked immunosorbent assays for the detection of serum antibodies against Coxiella burnetti (Q-fever) in ruminants : recommendations for use of serological tests on imported animals in New Zealand.

AIM: To make valid recommendations on the use of serological test methods for the detection of serum antibodies in ruminants against Coxiella burnetii (Q-fever), by comparing the performance of the complement fixation test (CFT) and two ELISA, and by identifying reasons for discrepancies between the test methods. METHODS: A total of 73 serum samples from infected cattle, 69 from infected goats, and 100 samples from non-infected cattle and 57 samples from non-infected sheep, as well as 95 samples from infected cattle herds (mix of seropositive and seronegative samples), were tested using the CFT, the IDEXX ELISA (I-ELISA) and the Pourquier ELISA (P-ELISA). A mixed panel of 12 serum samples from sheep from inter-laboratory proficiency testing (proficiency panel) was also tested using the CFT and both ELISA, and further investigated using IgG- and IgM-specific ELISA. RESULTS: Generally, the two commercial ELISA were more sensitive than the CFT for the detection of infected ruminants. Good agreement between ELISA for positive and negative results was found for samples from the infected herd, while results for the positive panels varied between the two ELISA. For the total of the positive serum panels, the I-ELISA detected 95% of samples as positive or suspicious, while the P-ELISA detected only 81%. In the P-ELISA, more samples were considered suspicious (18%) than in the I-ELISA (14%). All sera from non-infected sheep and cattle tested negative in the serological test methods employed, except for one positive sample from a sheep in the P-ELISA. Further investigation revealed that a CFT-positive but ELISA-negative result was due to high IgM and low IgG reactivity. CONCLUSIONS: The two commercial ELISA were more sensitive than the CFT in all panels from infected ruminants. However, they could only detect IgG. The I-ELISA should be the serological test method of choice for cattle, sheep and goats for import testing of animals into New Zealand because it was more sensitive than the P-ELISA and was equally specific to the PELISA and the CFT. For other animal species, such as deer and camelids, the CFT should still be used since none of the ELISA has been evaluated for these species. This study has shown that the two commercial ELISA will detect the majority of infected ruminants but may miss animals that have not developed an IgG response.

Carotenoid, tocopherol, and retinol concentrations in elderly human brain.

BACKGROUND: Antioxidants, such as tocopherols and carotenoids, have been implicated in the prevention of degenerative diseases. Although correlations have been made between diseases and tissue levels of antioxidants, to date there are no reports of individual carotenoid concentrations in human brain. OBJECTIVE: To measure the major carotenoids, tocopherols, and retinol in frontal and occipital regions of human brain. DESIGN: Ten samples of brain tissue from frontal lobe cortex and occipital cortex of five cadavers were examined. Sections were dissected into gray and white matter, extracted with organic solvents, and analyzed by HPLC. RESULTS: At least 16 carotenoids, 3 tocopherols, and retinol were present in human brain. Major carotenoids were identified as lutein, zeaxanthin, anhydrolutein, alpha- cryptoxanthin, beta- cryptoxanthin, alpha-carotene, cis- and trans-betacarotene, and cis- and trans-lycopene. Xanthophylls (oxygenated carotenoids) accounted for 66-77% of total carotenoids in all brain regions examined. Similar to neural retina, the ratio of zeaxanthin to lutein was high and these two xanthophylls were significantly correlated (p <0.0001). The tocopherol isomers occurred in the brain over a wider range of mean concentrations (0.11-17.9 nmol/g) than either retinol (87.8 - 163.3 pmol/g) or the identified carotenoids (1.8-23.0 pmol/g). CONCLUSIONS: The frontal cortex, generally vulnerable in Alzheimer's disease, had higher concentrations of all analytes than the occipital cortex which is generally unaffected. Moreover, frontal lobes, but not occipital lobes, exhibited an age-related decline in retinol, total tocopherols, total xanthophylls and total carotenoids. The importance of these differences and the role(s) of these antioxidants in the brain remain to be determined.