Attention-deficit/hyperactivity disorder in a population isolate: linkage to loci at 4q13.2, 5q33.3, 11q22, and 17p11

Attention-deficit/hyperactivity disorder (ADHD [MIM 143465]) is the most common behavioral disorder of childhood. Twin, adoption, segregation, association, and linkage studies have confirmed that genetics plays a major role in conferring susceptibility to ADHD. We applied model-based and model-free linkage analyses, as well as the pedigree disequilibrium test, to the results of a genomewide scan of extended and multigenerational families with ADHD from a genetic isolate. In these families, ADHD is highly comorbid with conduct and oppositional defiant disorders, as well as with alcohol and tobacco dependence. We found evidence of linkage to markers at chromosomes 4q13.2, 5q33.3, 8q11.23, 11q22, and 17p11 in individual families. Fine mapping applied to these regions resulted in significant linkage in the combined families at chromosomes 4q13.2 (two-point allele-sharing LOD score from LODPAL = 4.44 at D4S3248), 5q33.3 (two-point allele-sharing LOD score from LODPAL = 8.22 at D5S490), 11q22 (two-point allele-sharing LOD score from LODPAL = 5.77 at D11S1998; multipoint nonparametric linkage [NPL]-log[P value] = 5.49 at approximately 128 cM), and 17p11 (multipoint NPL-log [P value] >12 at approximately 12 cM; multipoint maximum location score 2.48 [alpha = 0.10] at approximately 12 cM; two-point allele-sharing LOD score from LODPAL = 3.73 at D17S1159). Additionally, suggestive linkage was found at chromosome 8q11.23 (combined two-point NPL-log [P value] >3.0 at D8S2332). Several of these regions are novel (4q13.2, 5q33.3, and 8q11.23), whereas others replicate already-published loci (11q22 and 17p11). The concordance between results from different analytical methods of linkage and the replication of data between two independent studies suggest that these loci truly harbor ADHD susceptibility genes.     

Rat brain arachidonic acid metabolism is increased by a 6-day intracerebral ventricular infusion of bacterial lipopolysaccharide

In a rat model of acute neuroinflammation, produced by a 6-day intracerebral ventricular infusion of bacterial lipopolysaccharide (LPS), we measured brain activities and protein levels of three phospholipases A2 (PLA2) and of cyclo-oxygenase-1 and -2, and quantified other aspects of brain phospholipid and fatty acid metabolism. The 6-day intracerebral ventricular infusion increased lectin-reactive microglia in the cerebral ventricles, pia mater, and the glial membrane of the cortex and resulted in morphological changes of glial fibrillary acidic protein (GFAP)-positive astrocytes in the cortical mantel and areas surrounding the cerebral ventricles. LPS infusion increased brain cytosolic and secretory PLA2 activities by 71% and 47%, respectively, as well as the brain concentrations of non-esterified linoleic and arachidonic acids, and of prostaglandins E2 and D2. LPS infusion also increased rates of incorporation and turnover of arachidonic acid in phosphatidylethanolamine, plasmenylethanolamine, phosphatidylcholine, and plasmenylcholine by 1.5- to 2.8-fold, without changing these rates in phosphatidylserine or phosphatidylinositol. These observations suggest that selective alterations in brain arachidonic acid metabolism involving cytosolic and secretory PLA2 contribute to early pathology in neuroinflammation.     

Quantifying conversion of linoleic to arachidonic and other n-6 polyunsaturated fatty acids in unanesthetized rats

Isotope feeding studies report a wide range of conversion fractions of dietary shorter-chain polyunsaturated fatty acids (PUFAs) to long-chain PUFAs, which limits assessing nutritional requirements and organ effects of arachidonic (AA, 20:4n-6) and docosahexaenoic (DHA, 22:6n-3) acids. In this study, whole-body (largely liver) steady-state conversion coefficients and rates of circulating unesterified linoleic acid (LA, 18:2n-6) to esterified AA and other elongated n-6 PUFAs were quantified directly using operational equations, in unanesthetized adult rats on a high-DHA but AA-free diet, using 2 h of intravenous [U-¹³C]LA infusion. Unesterified LA was converted to esterified LA in plasma at a greater rate than to esterified γ-linolenic (γ-LNA, 18:3n-6), eicosatrienoic acid (ETA, 20:3n-6), or AA. The steady-state whole-body synthesis-secretion (conversion) coefficient to AA equaled 5.4 × 10⁻³ min⁻¹, while the conversion rate (coefficient × concentration) equaled 16.1 μmol/day. This rate exceeds the reported brain AA consumption rate by 27-fold. As brain and heart cannot synthesize significant AA from circulating LA, liver synthesis is necessary to maintain their homeostatic AA concentrations in the absence of dietary AA. The heavy-isotope intravenous infusion method could be used to quantify steady-state liver synthesis-secretion of AA from LA under different conditions in rodents and in humans.     

Comparative analysis of the flea fauna and its epizootic importance in the deserts of Southern Kazakhstan

Common features and interregional differences in the structure of the flea fauna from Moiynkum (Chu-Talas watershed), Eastern Kyzyl Kum and Betpak Dala are described. The main role of the fleas Xenopsylla gerbilli minax (Moiynkum and Betpak Dala) and X. gerbilli caspica (Eastern Kyzyl Kum) in the transmission of plague microbes is demonstrated. The long-term dynamics of these species population in different desert regions were studied. The main factors responsible for this dynamics are demonstrated.     

Measuring Brain Uptake and Incorporation into Brain Phosphatidylinositol of Plasma myo-[2H6]Inositol in Unanesthetized Rats: An Approach to Estimate In vivo Brain Phosphatidylinositol Turnover

The in vivo rate of turnover of phosphatidylinositol (PtdIns) in brain is not known. In brain, certain receptor-mediated signal transduction involves metabolism of PtdIns and a method to measure its turnover in awake animals is useful in studying the effect of lithium and other therapeutic agents. In a method described here, rats were infused subcutaneously with myo-[²H₆]inositol (Ins*) using an osmotic pump and, at 1 and 8 weeks, concentrations of free myo-inositol (Ins) and Ins* in plasma and brain were measured by GC-MS (chemical ionization). Also, PtdIns and PtdIns* together in brain were isolated, and Ins and Ins* from their headgroups were released enzymatically and specific activity of incorporated inositol was measured. The specific activity of inositol reached a steady state in plasma within 1 week of infusion, but not in brain even at 8 weeks. However, in brain, the specific activity of phosphatidylinositol was same as that of inositol at both time-points, suggestive of fast turnover of PtdIns. The animal experiment and the analytical methodology described here should be useful for measuring the rate of turnover of brain PtdIns in pathological and drug treatment conditions.     

Rough sheets and smooth tubules

The endoplasmic reticulum (ER) has distinct morphological domains composed of sheets and tubules, which differ in their characteristic membrane curvature. Key proteins may drive the formation of these structural morphologies, which in turn could generate the rough and smooth functional domains of the ER.     

Probing sialic acid binding Ig-like lectins (siglecs) with sulfated oligosaccharides

Soluble siglecs-1, -4, -5, -6, -7, -8, -9, and -10 were probed with polyacrylamide glycoconjugates in which: 1) the Neu5Ac residue was substituted by a sulfate group (Su); 2) glycoconjugates contained both Su and Neu5Ac; 3) sialoglycoconjugates contained a tyrosine-O-sulfate residue. It was shown that sulfate derivatives of LacNAc did not bind siglecs-1, -4, -5, -6, -7, -8, -9, and -10; binding of 6'-O-Su-LacNAc to siglec-8 was stronger than binding of 3'SiaLacNAc. The relative affinity of 3'-O-Su-TF binding to siglecs-1, -4, and -8 was similar to that of 3'SiaTF. 3'-O-Su-Le(c) displayed two-fold weaker binding to siglec-1 and siglec-4 than 3'SiaLe(c). The interaction of soluble siglecs with sulfated oligosaccharides containing sialic acid was also studied. It was shown that siglecs-1, -4, -5, -6, -7, -9, and -10 did not interact with these compounds; binding of 6-O-Su-3'SiaLacNAc and 6-O-Su-3'SiaTF to siglec-8 was weaker than that of the corresponding sulfate-free sialoside probes. Siglec-8 displayed affinity to 6'-O-Su-LacNAc and 6'-O-Su-SiaLe(x), and defucosylation of the latter compound led to an increase in the binding. Sialoside probes containing tyrosine-O-sulfate residue did not display increased affinity to siglecs-1 and -5 compared with glycoconjugates containing only sialoside. Cell-bound siglecs-1, -5, -7, and -9 did not interact with 6-O-Su-3'SiaLacNAc, whereas the sulfate-free probe 3'SiaLacNAc demonstrated binding. In contrast, the presence of sulfate in 6-O-Su-6'SiaLacNAc did not affect binding of the sialoside probe to siglecs. 6'-O-Su-SiaLe(x) displayed affinity to cell-bound siglecs-1 and -5; its isomer 6-O-Su-SiaLe(x) bound more strongly to siglecs-1, -5, and -9 than SiaLe(x).