Density and function of central serotonin (5-HT) transporters, 5-HT1A and 5-HT2A receptors, and effects of their targeting on BTBR T+tf/J mouse social behavior

BTBR mice are potentially useful tools for autism research because their behavior parallels core social interaction impairments and restricted-repetitive behaviors. Altered regulation of central serotonin (5-HT) neurotransmission may underlie such behavioral deficits. To test this, we compared 5-HT transporter (SERT), 5-HT(1A) and 5-HT(2A) receptor densities among BTBR and C57 strains. Autoradiographic [(3) H] cyanoimipramine (1 nM) binding to SERT was 20-30% lower throughout the adult BTBR brain as compared to C57BL/10J mice. In hippocampal membrane homogenates, [(3) H] citalopram maximal binding (B(max) ) to SERT was 95 ± 13 fmol/mg protein in BTBR and 171 ± 20 fmol/mg protein in C57BL/6J mice, and the BTBR dissociation constant (K(D) ) was 2.0 ± 0.3 nM versus 1.1 ± 0.2 in C57BL/6J mice. Hippocampal 5-HT(1A) and 5-HT(2A) receptor binding was similar among strains. However, 8-OH-DPAT-stimulated [(35) S] GTPγS binding in the BTBR hippocampal CA(1) region was 28% higher, indicating elevated 5-HT(1A) capacity to activate G-proteins. In BTBR mice, the SERT blocker, fluoxetine (10 mg/kg) and the 5-HT(1A) receptor partial-agonist, buspirone (2 mg/kg) enhanced social interactions. The D(2) /5-HT(2) receptor antagonist, risperidone (0.1 mg/kg) reduced marble burying, but failed to improve sociability. Overall, altered SERT and/or 5-HT(1A) functionality in hippocampus could contribute to the relatively low sociability of BTBR mice.     

On resin amino acid side chain attachment strategy for the head to tail synthesis of new glutamine containing gramicidin-S analogs and their antimicrobial activity

The alarming increase in infections caused by multiple drug resistant bacteria including methicillin-resistant Staphylococcus aureus has prompted a desperate search for new antimicrobials. Augmenting the discoveries of completely new scaffolds with antimicrobial activity are efforts aimed at modifying existing molecules to optimize activity or reduce toxicity. We report herein the parallel solid-phase synthesis of analogues of the cationic antimicrobial peptide gramicidin S (GS) using amino acid side chain attachment strategy. The ornithine (Orn) residues were replaced by glutamine (Gln) and the aromatic d-phenylalanine (Phe) were replaced by different aromatic d-amino acids. Additional Gln containing GS analogues with all the possible combinations of the hydrophobic amino acids valine and leucine were also synthesized. In this work we also report the antibacterial activity of these analogs against several clinically-important drug-resistant Gram-positive and Gram-negative pathogens.     

Statins enhance formation of phagocyte extracellular traps

Statins are inhibitors of 3-hydroxy 3-methylglutaryl coenzyme A (HMG-CoA) reductase, the rate-limiting enzyme in cholesterol biosynthesis. Recent clinico-epidemiologic studies correlate patients receiving statin therapy with having reduced mortality associated with severe bacterial infection. Investigating the effect of statins on the innate immune capacity of phagocytic cells against the human pathogen Staphylococcus aureus, we uncovered a beneficial effect of statins on bacterial clearance by phagocytes, although, paradoxically, both phagocytosis and oxidative burst were inhibited. Probing instead for an extracellular mechanism of killing, we found that statins boosted the production of antibacterial DNA-based extracellular traps (ETs) by human and murine neutrophils and also monocytes/macrophages. The effect of statins to induce phagocyte ETs was linked to sterol pathway inhibition. We conclude that a drug therapy taken chronically by millions alters the functional behavior of phagocytic cells, which could have ramifications for susceptibility and response to bacterial infections in these patients.     

A gene involved in control of human cellular senescence on human chromosome 1q.

Normal cells in culture exhibit limited division potential and have been used as a model for cellular senescence. In contrast, tumor-derived or carcinogen- or virus-transformed cells are capable of indefinite division. Fusion of normal human diploid fibroblasts with immortal human cells yielded hybrids having limited life spans, indicating that cellular senescence was dominant. Fusions of various immortal human cell lines with each other led to the identification of four complementation groups for indefinite division. The purpose of this study was to determine whether human chromosome 1 could complement the recessive immortal defect of human cell lines assigned to one of the four complementation groups. Using microcell fusion, we introduced a single normal human chromosome 1 into immortal human cell lines representing the complementation groups and determined that it caused loss of proliferative potential of an osteosarcoma-derived cell line (TE85), a cytomegalovirus-transformed lung fibroblast cell line (CMV-Mj-HEL-1), and a Ki-ras(+)-transformed derivative of TE85 (143B TK-), all of which were assigned to complementation group C. This chromosome 1 caused no change in proliferative potential of cell lines representing the other complementation groups. A derivative of human chromosome 1 that had lost most of the q arm by spontaneous deletion was unable to induce senescence in any of the immortal cell lines. This finding indicates that the q arm of human chromosome 1 carries a gene or set of genes which is altered in the cell lines assigned to complementation group C and is involved in the control of cellular senescence.     

Omega-3 phospholipids from fish suppress hepatic steatosis by integrated inhibition of biosynthetic pathways in dietary obese mice

Non-alcoholic fatty liver disease (NAFLD) accompanies obesity and insulin resistance. Recent meta-analysis suggested omega-3 polyunsaturated fatty acids DHA and EPA to decrease liver fat in NAFLD patients. Anti-inflammatory, hypolipidemic, and insulin-sensitizing effects of DHA/EPA depend on their lipid form, with marine phospholipids showing better efficacy than fish oils. We characterized the mechanisms underlying beneficial effects of DHA/EPA phospholipids, alone or combined with an antidiabetic drug, on hepatosteatosis. C57BL/6N mice were fed for 7 weeks an obesogenic high-fat diet (cHF) or cHF-based interventions: (i) cHF supplemented with phosphatidylcholine-rich concentrate from herring (replacing 10% of dietary lipids; PC), (ii) cHF containing rosiglitazone (10 mg/kg diet; R), or (iii) PC + R. Metabolic analyses, hepatic gene expression and lipidome profiling were performed. Results showed that PC and PC + R prevented cHF-induced weight gain and glucose intolerance, while all interventions reduced abdominal fat and plasma triacylglycerols. PC and PC + R also lowered hepatic and plasma cholesterol and reduced hepatosteatosis. Microarray analysis revealed integrated down-regulation of hepatic lipogenic and cholesterol biosynthesis pathways by PC, while R-induced lipogenesis was fully counteracted in PC + R. Gene expression changes in PC and PC + R were associated with preferential enrichment of hepatic phosphatidylcholine and phosphatidylethanolamine fractions by DHA/EPA. The complex down-regulation of hepatic lipogenic and cholesterol biosynthesis genes and the antisteatotic effects were unique to DHA/EPA-containing phospholipids, since they were absent in mice fed soy-derived phosphatidylcholine. Thus, inhibition of lipid and cholesterol biosynthesis associated with potent antisteatotic effects in the liver in response to DHA/EPA-containing phospholipids support their use in NAFLD prevention and treatment.     

Induction of muscle thermogenesis by high-fat diet in mice: association with obesity-resistance

The obesogenic effect of a high-fat (HF) diet is counterbalanced by stimulation of energy expenditure and lipid oxidation in response to a meal. The aim of this study was to reveal whether muscle nonshivering thermogenesis could be stimulated by a HF diet, especially in obesity-resistant A/J compared with obesity-prone C57BL/6J (B/6J) mice. Experiments were performed on male mice born and maintained at 30 degrees C. Four-week-old mice were randomly weaned onto a low-fat (LF) or HF diet for 2 wk. In the A/J LF mice, cold exposure (4 degrees C) resulted in hypothermia, whereas the A/J HF, B/6J LF, and B/6J HF mice were cold tolerant. Cold sensitivity of the A/J LF mice was associated with a relatively low whole body energy expenditure under resting conditions, which was normalized by the HF diet. In both strains, the HF diet induced uncoupling protein-1-mediated thermogenesis, with a stronger induction in A/J mice. Only in A/J mice: 1) the HF diet augmented activation of whole body lipid oxidation by cold; and 2) at 30 degrees C, oxygen consumption, total content, and phosphorylation of AMP-activated protein kinase (AMPK), and AICAR-stimulated palmitate oxidation in soleus muscle was increased by the HF diet in parallel with significantly increased leptinemia. Gene expression data in soleus muscle of the A/J HF mice indicated a shift from carbohydrate to fatty acid oxidation. Our results suggest a role for muscle nonshivering thermogenesis and lipid oxidation in the obesity-resistant phenotype of A/J mice and indicate that a HF diet could induce thermogenesis in oxidative muscle, possibly via the leptin-AMPK axis.     

Top-down mass spectrometry on low-resolution instruments: characterization of phosphopantetheinylated carrier domains in polyketide and non-ribosomal biosynthetic pathways

Mass spectrometry (MS) is an important tool for studying non-ribosomal peptide, polyketide, and fatty acid biosynthesis. Here we describe a new approach using multi-stage tandem MS on a common ion trap instrument to obtain high-resolution measurements of the masses of substrates and intermediates bound to phosphopantetheinylated (holo) carrier proteins. In particular, we report the chemical formulas of 12 diagnostic MS(3) fragments of the phosphopantetheine moiety ejected from holo carrier proteins during MS(2). We demonstrate our method by observing the formation of holo-AcpC, a putative acyl carrier protein from Streptococcus agalactiae.     

Neuronal co-processing of course deviations and head movements in locusts

Summary In Locusta migratoria, the major pathway from descending deviation detectors (DDNs; preceding paper, Hensler 1992) to wing motoneurons involves a population of thoracic interneurons (TINs). Nine TINs are characterized which receive input from cervical proprioreceptors. Responses to the combination of exteroreceptive input (signalling course deviation) and proprioreceptive input (monitoring movement and position of the head) are described and compared to those of DDNs to the same stimuli.Abbreviations AP action potential - DDN descending deviation detector neuron - TCG tritocerebral giant neuron - TIN thoracic interneuron