Interdigital transducer for acousto-optic tunable filter on LiNbO3

Interdigital transducers on X-cut Y-propagating lithium niobate generate parasitic Bleustein-Gulyaev waves which reduce the acoustic efficiency. An increased number of electrode pairs improves the efficiency and an AOTF driven by an RF electric power of only 6 mW can be realised     

Flavor, not postingestive, cues contribute to the salience of proteins as targets in aversion conditioning.

Proteins have proven to be more salient targets for aversion conditioning than carbohydrates. The present studies examined the contribution of flavor and postingestive factors to the salience of proteins as targets in aversion conditioning in the rat. Two methods for separating flavor and postingestive cues were used, sham feeding and intragastric gavage. Both methods agreed in indicating that postingestive consequences of protein consumption were neither necessary nor sufficient for the development of more severe protein than carbohydrate aversions. Differences in palatability did not appear likely to be the basis of protein salience because when acceptability or palatability of the nutrient solutions was matched, aversions to protein continued to be more severe. Differences in odor intensity of nutrient solutions may be important because when an odorant was added to a carbohydrate solution, the severity of aversions to protein and carbohydrate were no longer different. These results indicate that the presence of both taste and odor cues in target nutrients may contribute importantly to their salience. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Deficits in discriminated learning remain despite clearance of long-term persistent viral infection in mice

Mice persistently infected with lymphocytic choriomeningitis virus (LCMV) exhibit impaired learning ability. In this report, we determined whether clearance of the virus was associated with restoration of behavioral function. Neonatal Balb/cByJ mice were persistently infected with LCMV and tested as adults in a nonconditional spatial discrimination task. The presence of viral proteins in neurons was confirmed immunohistochemically and infectious virus was quantified in the blood by plaque assay. LCMV-infected adult mice made more errors in a Y-maze avoidance task compared to sham-inoculated controls. After the initial behavioral analysis, infected and control mice received a dose of cytotoxic T-lymphocytes sufficient to clear virus from these mice. Following complete clearance of the virus, mice were re-tested in the behavioral task, 5 months after the original test. No reversal of the learning deficit was seen following viral clearance; mice that had been cleared of the virus and those that remained persistently infected behaved similarly. These data indicate that persistent LCMV infection of the CNS lasting up to 7 months results in discriminated learning impairments that are not reversed by subsequent anti-viral immunocytotherapy.     

Effect of ribosomal proteins on synthesis and assembly of preribosomal particles in isolated rat liver nuclei

Ribosomal proteins are rapidly taken up by isolated rat liver nuclei. The proteins are localized mainly in the nucleolus and are found associated with a nucleolar 80 S particle containing newly synthesized 45 S RNA. Ribosomal proteins in the nucleoplasm were associated with particles containing 18 and 28 S RNAs. In the absence of ribosomal proteins in the incubations, there was a decrease in the amount of newly synthesized 45, 18, and 28 S RNAs and an increase in low molecular weight RNA in both the nucleolus and nucleoplasm. This in vitro system appears to be useful for studies on the formation of ribosomal particles in the nucleus.     

Loss of BOK Has a Minor Impact on Acetaminophen Overdose-Induced Liver Damage in Mice

Acetaminophen (APAP) is one of the most commonly used analgesic and anti-pyretic drugs, and APAP intoxication is one of the main reasons for liver transplantation following liver failure in the Western world. While APAP poisoning ultimately leads to liver necrosis, various programmed cell death modalities have been implicated, including ER stress-triggered apoptosis. The BCL-2 family member BOK (BCL-2-related ovarian killer) has been described to modulate the unfolded protein response and to promote chemical-induced liver injury. We therefore investigated the impact of the loss of BOK following APAP overdosing in mice. Surprisingly, we observed sex-dependent differences in the activation of the unfolded protein response (UPR) in both wildtype (WT) and Bok^-/- mice, with increased activation of JNK in females compared with males. Loss of BOK led to a decrease in JNK activation and a reduced percentage of centrilobular necrosis in both sexes after APAP treatment; however, this protection was more pronounced in Bok^-/- females. Nevertheless, serum ALT and AST levels of Bok^-/- and WT mice were comparable, indicating that there was no major difference in the overall outcome of liver injury. We conclude that after APAP overdosing, loss of BOK affects initiating signaling steps linked to ER stress, but has a more minor impact on the outcome of liver necrosis. Furthermore, we observed sex-dependent differences that might be worthwhile to investigate.     

Modulation of potassium channel function by methionine oxidation and reduction

Oxidation of amino acid residues in proteins can be caused by a variety of oxidizing agents normally produced by cells. The oxidation of methionine in proteins to methionine sulfoxide is implicated in aging as well as in pathological conditions, and it is a reversible reaction mediated by a ubiquitous enzyme, peptide methionine sulfoxide reductase. The reversibility of methionine oxidation suggests that it could act as a cellular regulatory mechanism although no such in vivo activity has been demonstrated. We show here that oxidation of a methionine residue in a voltage-dependent potassium channel modulates its inactivation. When this methionine residue is oxidized to methionine sulfoxide, the inactivation is disrupted, and it is reversed by coexpression with peptide methionine sulfoxide reductase. The results suggest that oxidation and reduction of methionine could play a dynamic role in the cellular signal transduction process in a variety of systems.     

Anti-Inflammatory Effects of Analogues of N-Acyl Homoserine Lactones on Eukaryotic Cells

Background: Since acyl-homoserine lactone (AHL) profiling has been described in the gut of healthy subjects and patients with inflammatory bowel disease (IBD), the potential effects of these molecules on host cells have raised interest in the medical community. In particular, natural AHLs such as the 3-oxo-C12-HSL exhibit anti-inflammatory properties. Our study aimed at finding stable 3-oxo-C12-HSL-derived analogues with improved anti-inflammatory effects on epithelial and immune cells. Methods: We first studied the stability and biological properties of the natural 3-oxo-C12-HSL on eukaryotic cells and a bacterial reporter strain. We then constructed and screened a library of 22 AHL-derived molecules. Anti-inflammatory effects were assessed by cytokine release in an epithelial cell model, Caco-2, and a murine macrophage cell line, RAW264.7, (respectively, IL-8 and IL-6) upon exposure to the molecule and after appropriate stimulation (respectively, TNF-α 50 ng/mL and IFN-γ 50 ng/mL, and LPS 10 ng/mL and IFN-γ 20 U/mL). Results: We found two molecules of interest with amplified anti-inflammatory effects on mammalian cells without bacterial-activating properties in the reporter strain. The molecules furthermore showed improved stability in biological medium compared to the native 3-oxo-C12-HSL. Conclusions: We provide new bio-inspired AHL analogues with strong anti-inflammatory properties that will need further study from a therapeutic perspective.     

Similarity of nucleotide interactions of BiP and GTP-binding proteins

BiP is a member of the Hsp70 heat shock protein family found in the lumen of the endoplasmic reticulum, that binds to a variety of proteins destined to be secreted. Substance P (SP) has been used as a model peptide to study the interaction of BiP with protein substrates. SP stimulates BiP ATPase activity and forms a stable complex with BiP that is dissociated in the presence of levels of ATP > 50 microM. At lower concentrations of ATP, the SP remains bound to BiP, and the results are consistent with the view that a BiP-ATP complex is initially formed that reacts with SP to form a ternary complex, SP-BiP-ATP. Hydrolysis of ATP in this complex yields a SP-BiP-ADP complex. An exchange of ATP with ADP bound to BiP has also been demonstrated, and the results suggest that the interactions of BiP with ATP resemble those seen with GTP-binding proteins and GTP.