Species identification in meat products using real-time PCR.

One of the most convenient methods for the identification of animal species in processed meat products is the examination of DNA sequences. Real-time polymerase chain reaction (qPCR) techniques are particularly suitable because even small fragments of DNA formed during heat processing of the meat can be amplified and identified. A real-time PCR method has been developed and evaluated for the identification of processed meat products. In test mixtures containing beef, pork, horse, mutton, chicken and turkey, it was possible to identify these species down to a level of 0.05%. By adjusting the number of cycles, it was possible to detect levels as low as 0.01% of these species. Cross-reactivity between these species was not found, except for pure horsemeat (250 ng DNA) in the assay for turkey meat. Cross-reactivity of deer, roe, ostrich, kangaroo, goat, domestic duck, mallard, goose, pigeon, guinea fowl, quail and pheasant was also investigated and it was found that amounts as high as 250 ng DNA of these species in the reaction vial did not result in (false) positive signals except for amounts higher than 125 ng deer DNA and higher than 50 ng pigeon DNA in the determination of chicken and beef, respectively. More than 150 meat samples were examined using DNA hybridization and real-time PCR. A comparison of the results showed a better performance of the real-time procedure compared to DNA hybridization.

[Treatment of patients with the chronic-fatigue syndrome]. / Behandeling van patiënten met het chronische-vermoeidheidssyndroom.

In the last few years, the chronic-fatigue syndrome has been recognised as an important health problem. In a recent report, the Health Council of the Netherlands suggested that the capacity for treatment be increased. Cognitive behavioural therapy and graded exercise training are treatment options of first choice. A recently published, uncontrolled evaluation of a Dutch clinical rehabilitation programme based partly on these methods proved to be successful. Unfortunately, due to the uncontrolled character of the study, it remains unclear which elements in the treatment were responsible for the success. Which patients should be included in a costly clinical rehabilitation programme also remains unclear. More in general, there is room for empirical studies of treatment allocation, not in the least because of the frequently occurring comorbidity. Good progress has been made in the treatment of the chronic-fatigue syndrome, but we are still far removed from evidence-based, stepped care, treatment programmes.

Proficiency studies on the determination of paralytic shellfish poisoning toxins in shellfish.

Paralytic shellfish poisoning toxins are produced by dinoflagellates. Shellfish filtering these unicellular algae will accumulate the toxins and pose a health risk when consumed by man. In the European Union, paralytic shellfish poisoning toxins in bivalve molluscs are regulated at a maximum content of 80 microg/100 g (91/492/EEC). The current reference method in the European Union is the mouse bioassay, but alternative methods including the liquid chromatography methodology are preferred for ethical reasons. Analyses of suspected shellfish batches revealed, however, unacceptable differences in results reported by a small group of Dutch laboratories all using liquid chromatography methods with precolumn derivatization, followed by fluorescence detection. Therefore, a series of proficiency studies were undertaken among these laboratories. In the first three studies, participants were more or less allowed their own choice of method execution details. This approach yielded unsatisfactory results. A fourth study was then initiated in which a standardized method was mandatory. Two types of test material were used in the fourth study: lyophilized Cardium tuberculatum material containing saxitoxin (STX) and decarbamoyl-saxitoxin (dc-STX), and lyophilized mussel material containing dc-STX. The latter material was investigated in an interlaboratory study involving 15 participants and was considered as the reference material. Among the four laboratories, coefficients of variation (ANOVA) for C. tuberculatum material were 10% (n = 11) and 9% (n = 12) for STX and dc-STX, respectively, and for the reference material was 8% (n = 12) for dc-STX. The joint efforts showed that variability in analysis results between laboratories that all apply more or less the same method can be drastically improved if the methodology is rigorously standardized.

The influence of depressive state features on trait measurement.

BACKGROUND: Certain personality characteristics may change during depression, reflecting temporary states, while others remain stable. This study investigates the stability of personality during depression. Identification of depression-sensitive personality traits may help to elucidate the mechanisms that influence course and outcome of depression. METHODS: For 42 ambulatory and 38 day care patients with a depressive disorder, depression severity and personality characteristics were measured repeatedly during a 12 week-period. The total HDRS score was indicative of depression severity, while the NEO-FFI was used for measurement of basic personality traits and the IPS for depression-specific traits. RESULTS: In 12 weeks, depression severity significantly decreased for both patient groups. The Big Five traits Neuroticism and Extraversion and all but one aspect of Interpersonal sensitivity showed depression-related changes towards the normal range. Openness, Altruism and Conscientiousness remained stable. LIMITATIONS: The number of patients excluded from the study due to missing data is substantial. Furthermore, it was not possible to control for treatment influence due to a double-blind design. CONCLUSIONS: Neuroticism, Extraversion and Interpersonal sensitivity scores are likely to reflect state components during a depression, while the stability of Openness, Conscientiousness and Altruism scores indicates pure personality traits.

Determination of 4-hexylresorcinol in shrimp by liquid chromatography with fluorescence detection.

A method was developed to determine 4-hexylresorcinol in shrimp meat. The procedure is based on extraction of test portions with methanol followed by liquid chromatographic analysis of the extracts, using a reversed-phase column and fluorimetric detection (excitation: 280 nm, and emission: 310 nm). The confidence interval of the recovery in working range of 1.5-2.5 mg/kg was 81.6 +/- 0.8%. The relative standard deviation in the working range was 2.1%. Limits of quantitation and detection were 6.59 and 1.98 ng/mL extract, respectively, corresponding to 0.26 and 0.08 mg/kg in shrimp.

A comparison of the 'Hamilton Rating Scale for Depression' and the 'Montgomery-Asberg Depression rating Scale'.

Although the Hamilton Rating Scale for Depression (HRSD) is the most frequently used rating scale for quantifying depressive states, it has been criticized for its reliability and its usability in clinical practice. This criticism is less applying to the Montgomery-Asberg Depression Rating Scale (MADRS). Goal of the present study is to investigate the reliability and validity, and clinical relationship between the HRSD and the MADRS. For 60 out-patients with diagnosed depression (DSM IV296.2x, 296.3x, 300.40 and 311.00), the HRSD and MADRS were scored at baseline and 6 weeks later by an independent rater according to a structured interview. Also the Clinical Global Impression (CGI) was assessed by a psychiatrist. Satisfying agreement was found between the totalscores (r= .75, p>.000 en r=.92, p>.000 respectively, at baseline and 6 weeks later). Furthermore agreement was found between the items of both scales, and these agree with the clinical impression. The reliability of the MADRS is more stable than the reliability of the HRSD (α = .6367 and α =.8900 vs α = .2193 and α = .8362 at baseline and at endpoint respectively). Considering the ease of scoring both scales in one interview and the widely international use of the HRSD, scoring both the HRSD and the MADRS to measure the severity of a depression seems to be an acceptabel covenant.

Liquid chromatographic determination of histamine in fish, sauerkraut, and wine: interlaboratory study.

An interlaboratory study of the liquid chromatographic (LC) determination of histamine in fish, sauerkraut, and wine was conducted. Diminuted and homogenized samples were suspended in water followed by clarification of extracts with perchloric acid, filtration, and dilution with water. After LC separation on a reversed-phase C18 column with phosphate buffer (pH 3.0)--acetonitrile (875 + 125, v/v) as mobile phase, histamine was measured fluorometrically (excitation, 340 nm; emission, 455 nm) in samples and standards after postcolumn derivatization with o-phthaldialdehyde (OPA). Fourteen samples (including 6 blind duplicates and 1 split level) containing histamine at about 10-400 mg/kg or mg/L were analyzed singly according to the proposed procedure by 11 laboratories. Results from one participant were excluded from statistical analysis. For all samples analyzed, repeatability relative standard deviations varied from 2.1 to 5.6%, and reproducibility relative standard deviations ranged from 2.2 to 7.1%. Averaged recoveries of histamine for this concentration range varied from 94 to 100%.

A terminating reagent for the peroxidase-labelled enzyme immunoassay.

Addition of a low concentration of sodium azide completely stops colour development in a peroxidase-labelled enzyme immunoassay using 2,2'-azino-di(3-ethylbenzthiazoline sulphonic acid-6) as substrate. Whereas high concentrations of azide cause a decrease in the colour intensity, the low concentrations used here have no significant affect on the colour.

Solvent-generated ion-exchange systems with anionic surfactants for rapid separations of amino acids.

The retention behaviour of amino acids in phase systems consisting of a hydrophobic solid support as the stationary phase and water-organic solvent mixtures containing a small amount of an anionic detergent as the mobile phase was investigated. Such phase systems are found to behave like conventional ion-exchange systems. The degree and order of retention of amino acids can be influenced by changing the temperature, the nature of the hydrophobic support, the pH and the nature and concentration of the anionic detergent, organic constituent and counter ion in the eluent. In many instances this solvent-generated (dynamic) ion-exchange chromatography shows a greater selectivity than conventional ion-exchange systems towards amino acids. The results obtained so far indicate that a complete separation of the 19 protein amino acids by applying solvent gradients or/and multi-column system is possible within 30 min.