Diagnostic utility of abbreviated fluency measures in Alzheimer disease and vascular dementia.

BACKGROUND: Several studies indicate semantic fluency more sensitively discriminates patients with Alzheimer disease (AD) from normal elderly persons, with disproportionate impairment of semantic over phonemic fluency. OBJECTIVE: To determine the ability of abbreviated fluency measures in the clinic setting (1-minute letter F and animal fluency tests) to detect AD, and to assess whether difference scores between these measures discriminate patients with AD and vascular dementia (VaD) from normal elderly persons. METHODS: The authors studied patients with AD (n = 98) meeting National Institute of Neurological Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorders Association criteria, VaD patients (n = 18) meeting National Institute of Neurological Disorders and Stroke-Association Internationale pour la Recherche et l'Enseignement en Neurosciences criteria, cognitively impaired but not demented patients (CIND; n = 25), vascular CIND patients (VCIND; n = 24), and normal control subjects (NCs; n = 46). RESULTS: Analysis of covariance controlling for age, education, and overall impairment indicated all groups generated fewer animal names compared with NCs, whereas only VaD patients generated fewer letter F words compared with NCs. On standardized scores, patients with AD and CIND, unlike those with VCIND and VaD, scored significantly worse on the animal fluency test than on the letter F fluency test. The animal fluency test was superior in discriminating all patient groups from NCs. Positive likelihood ratios (PLRs) revealed animal fluency scores <15 were 20 times more likely in a patient with AD than in an NC (sensitivity = 0.88; specificity = 0.96). Letter F scores <4 discriminated VaD from AD patients (PLR = 4.0; sensitivity = 0.44; specificity = 0.90). Difference scores <0 (i.e., fewer animal than letter F words) discriminated patients with VCIND from those with CIND (PLR = 2.5; sensitivity = 0.32; specificity = 1.00). CONCLUSIONS: A 1-minute semantic fluency test can assist in early detection of dementia in the memory clinic setting.

Polymorphisms in the interleukin-10 and interferon gamma genes in Hodgkin lymphoma.

Genetic factors are known to be important in the development of Hodgkin lymphoma (HL). Interleukin-10 (IL-10) secretion by both malignant and reactive cells is thought to be important in the pathogenesis of HL especially Epstein-Barr virus (EBV) positive cases. Polymorphisms of the IL-10 gene have been reported to be associated with susceptibility to EBV infection. The cytotoxic response to EBV is determined by a Th1 biased immune response which is characterised by interferon gamma (IFNgamma) secretion. We therefore investigated polymorphisms in the IL-10 (-1082 G/A and -592 C/A) and IFNgamma (intron 1 CA repeat) genes as predisposing factors in the development 147 cases of HL. A difference of borderline statistical significance was demonstrated for the IFNgamma gene polymorphism but significance was lost when analysis was restricted to the common genotypes. No significant differences in the distributions of genotypes were found for the IL-10 gene polymorphisms. IL-10 and IFNgamma levels were also measured on 26 patients with HL. No statistically significant differences were detected when the results were analysed by genotype. We found little evidence IL-10 and IFNgamma genotypes predispose to the development of HL or influence the inflammatory host response.

Characterisation of human melatonin mt(1) and MT(2) receptors by CRE-luciferase reporter assay.

A cyclic AMP response element (CRE)-luciferase reporter gene assay was used to characterise the functional responses of human melatonin mt(1) and human melatonin MT(2) receptors, stably expressed in the human embryonic kidney cell line HEK293, to a series of six naphthalenic analogues of melatonin. By comparison to the observed melatonin-mediated inhibition of stimulated luciferase levels the naphthalenic series was identified as comprising agonists, partial agonists and one antagonist of melatonin mt(1) and melatonin MT(2) receptor function. Three of the agonist/partial agonist members of this series were also identified as displaying a functional selectivity for the melatonin MT(2) receptor. Competitive displacement of 2-[125I]iodomelatonin binding to the ovine pars tuberalis melatonin ML(1) receptor demonstrated a close correlation to the observed functional luciferase responses of the human melatonin mt(1) receptor. We conclude that the CRE-luciferase reporter gene assay provides an effective functional screening method for the pharmacological characterisation of human melatonin receptor subtypes.

The roles of valine 208 and histidine 211 in ligand binding and receptor function of the ovine Mel1a beta melatonin receptor.

Site-directed mutagenesis was used to study two residues, valine 208 and histidine 211, in transmembrane domain 5 of the ovine Mel1a beta melatonin receptor. A series of 4 mutants were constructed (V208A, V208L, H211F, H211L), and each engineered to contain a FLAG-epitope. Immunocytochemistry demonstrated that all the mutants were expressed in COS-7 cells at levels comparable to the FLAG-epitope tagged wild-type Mel1a beta receptor (approximately 120 fmol/mg protein). Ligand binding revealed however that all mutants had reduced affinities for 2-[125I]-iodomelatonin (Kd wild-type 139 pM, Kd mutants 320 to 989 pM). Competition studies, with a series of melatonin analogues, identified a probable interaction between histidine 211 and the 5-methoxy group of melatonin. The wild-type receptor and both valine 208 mutants displayed a dose-dependent melatonin mediated inhibition of cyclic AMP levels in HEK293 cells, with IC50 values in the same rank-order as their melatonin binding affinities. Both H211F and H211L, however, did not display any melatonin mediated effects and may suggest that histidine 211 is critical for melatonin mediated receptor activation.

Identification of Mel1a melatonin receptors in the human embryonic kidney cell line HEK293: evidence of G protein-coupled melatonin receptors which do not mediate the inhibition of stimulated cyclic AMP levels.

Binding assays using 2-[125I]iodomelatonin revealed high-affinity, guanosine 5'-O-(3-thiotriphosphate) sensitive, melatonin binding sites (B(max) 1.1 fmol/mg protein) in the human embryonic kidney cell line HEK293. Competition studies using the selective melatonin receptor antagonist luzindole and RT-PCR techniques identified these sites as human Mel1a melatonin receptors. Challenge of HEK293 cells with 1 microM melatonin had no effect on forskolin stimulated cyclic AMP levels, whereas in HEK293 cells engineered to stably over-express the human Mel1a melatonin receptor (B(max) > 400 fmol/mg protein) melatonin dose-dependently inhibited stimulated cyclic AMP levels (IC50 7.7 pM). These data may indicate that certain tissues, expressing low levels of G protein-coupled melatonin receptors, do not display melatonin mediated inhibition of cAMP.