Most serodiagnostic techniques have been evaluated for diagnosis of cystic hydatid disease caused by Echinococcus granulosus. Each, to varying degrees, has been shown to give false results, with considerable variation between laboratories. The comparative study was made concerning the sensitivity of the immunodiagnostic methods based on 58 sera from hydatid disease with different cyst locations. Latex agglutination, immunoelectrophoresis (IEP), and specific IgE, IgG enzyme‐linked immunosorbent assay (ELISA) tests were studied. Specific IgG ELISA AgB (antigen B‐rich fraction) was the most sensitive test (96.5%) and the least sensitive tests were specific IgE ELISA (24.1%) and IEP (25.8%). The low sensitivity of these two tests was due partly to the low reactivity detected in the sera of patients with lung hydatidosis. Initial laboratory studies showed purified antigens to be preferable to crude cyst fluid, regardless of the type of test used. For this reason, we evaluated the sensitivity and specificity of ELISA by using the purified antigen‐B‐rich fraction. In all, 117 sera were examined: 78 sera from patients with hydatidosis surgically confirmed, 15 sera from healthy control subjects, and 24 sera from patients with diseases other than hydatidosis. The method gave good results: 93.5% sensitivity, 89.7% specificity, and 92.3% diagnostic efficacy. J. Clin. Lab. Anal. 15:14–18, 2001. © 2001 Wiley‐Liss, Inc.

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Increasing evidence suggests that melatonin can exert some effect at nuclear level. Previous experiments using binding techniques clearly showed the existence of specific melatonin binding sites in cell nucleus of rat liver. To further identify these sites, nuclear extracts from rat hepatocytes were treated with different percentages of ammonium sulfate and purified by affinity chromatography. Subsequent ligand blot analysis shows the presence of two polypeptides of 60 and 74 kDa that bind specifically to melatonin. N-Terminal sequence analysis showed that the 60 kDa protein shares a high homology with rat calreticulin, whereas the 74 kDa protein shows no homology with any known protein. , compatible with other binding sites of melatonin in the cell. The presence of calreticulin was further identified by Western blot analysis, and the lack of endoplasmic reticulum contamination in our material was assessed by Western blot and immunostaining with anti-calnexin Ig. The results suggest that calreticulin may represent a new class of high-affinity melatonin binding sites involved in some functions of the indoleamine including genomic regulation.Keywords: affinity chromatography; calreticulin; melatonin; nuclear receptor purification; receptor binding.Melatonin is a highly preserved molecule throughout phylogeny. It appears in very ancient unicellular organisms [1], remaining unchanged in multicellular species including humans [2]. In mammals, the circadian rhythm of melatonin is produced through a photoperiodic-dependent synthesis by the pineal gland [3]. In turn, melatonin translates photoperiodic information from clock and calendar messages, acting as an endogenous synchronizer of several endocrine and nonendocrine rhythms [3]. This indoleamine is also produced by a variety of other tissues [4]. Melatonin exerts important regulatory influences on reproduction [5], and on neuroendocrine [6] and immune systems [7]. Moreover, it also controls cellular proliferation through regulatory effects on cell cycle kinetics [8], and prevents apoptosis in several tissues [9]. Recent studies have also focused on the antioxidant and free radical scavenging properties of melatonin [10][11][12][13].Except for the antioxidant, nonreceptor-mediated effects of melatonin, the actions of the indoleamine suggest the existence of specific receptors in the cell. Three related, but distinct high affinity G i -protein-coupled melatonin receptor subtypes have been cloned [14][15][16][17]. Membrane receptors for melatonin are now classified as mt 1 , MT 2 and MT 3 . In addition, biochemical and immunocytochemical studies in different mammalian tissues have shown the presence and accumulation of melatonin in the cell nuclei [18]. This nuclear localization of melatonin can be related to its described genomic effects including the regulation of the mRNA levels for antioxidant enzymes and the inducible isoform of nitric oxide synthase (iNOS) [19,20]. So far, no responding gene could be directly linked to the activation of membrane receptors by mela...