Intercellular communication in normal and regenerating rat liver: a quantitative analysis

We have compared intercellular communication in the regenerating and normal livers of weanling rats. The electrophysiological studies were conducted at the edge of the liver, and we have found that here as elsewhere in the liver there is a dramatic decrease in the number and size of gap junctions during regeneration. The area of hepatocyte membrane occupied by gap junctions is reduced 100-fold 29-35 h after hepatectomy. By combining observations made with the scanning electron microscope with our freeze fracture data we have estimated the number of "communicating interfaces" (areas of contact between hepatocytes that include at least one gap junction) formed by hepatocytes in normal and regenerating liver. In normal liver a hepatocyte forms gap junctions with every hepatocyte it contacts (approximately 6). In regenerating liver a hepatocyte forms detectable gap junctions with, on average, only one other hepatocyte. Intercellular spread of fluorescent dye and electric current is reduced in regenerating as compared with normal liver. The incidence of electric coupling is reduced from 100% of hepatocyte pairs tested in control liver to 92% in regenerating liver. Analysis of the spatial dependence of electronic potentials indicates a substantial increase in intercellular resistance in regenerating liver. A quantitative comparison of our morphological and physiological data is complicated by tortuous pattern of current flow and by inhomogeneities in the liver during regeneration. Nevertheless we believe that our results are consistent with the hypothesis that gap junctions are aggregates of channels between cell interiors

Chronic psychological stress was not ameliorated by omega-3 eicosapentaenoic acid (EPA)

Background: Chronic psychological stress and mental health disorders are endemic in Western culture where population dietary insufficiencies of omega-3 fatty acids (n-3FA) from seafood have been observed. Objective: This study was designed to test for a causal relationship between one of the most active components of fish oil, eicosapentaenoic acid (EPA), and chronic psychological stress. Method: A randomized double-blind, placebo-controlled clinical trial with parallel-assignment to two groups was designed (Trial Id: ACTRN12610000404022). The interventions were four EPA-rich fish oil capsules per day, delivering 2.2 g/d EPA (and 0.44 g/d DHA), or identical placebo (low-phenolic olive oil capsules with 5% fish oil to aid blinding). The primary outcome was the between-group difference on the Perceived Stress Scale (PSS-10) after 12 weeks supplementation. An a priori power analysis determined that group sizes of 43 would provide 80% power to detect a significant between-group difference of 12.5%, at α = 0.05. Ninety community members (64 females, 26 males) reporting chronic work stress were recruited via public advertising in northern NSW, Australia. Results: At baseline the omega-3 index (EPA + DHA as % to total fatty acids in red blood cell membranes) was 5.2% in both groups (SD = 1.6% control group; 1.8% active group). After supplementation this remained stable at 5.3% (SD = 1.6%) for the control group but increased to 8.9% (SD = 1.5%) for the active group, demonstrating successful incorporation of EPA into cells. Intention-to-treat (ITT) analysis found no significant between-group differences in PSS outcome scores post-intervention (b = 1.21, p = 0.30) after adjusting for sex (b = 2.36, p = 0.079), baseline PSS (b = 0.42, p = 0.001) and baseline logEPA [b = 1.41, p = 0.185; F(3, 86) = 8.47, p \u3c 0.01, n = 89, R-square = 0.243]. Discussion: Treatment increased cell membrane EPA but, contrary to the hypothesis, there was no effect on perceived stress. Limitations included an imbalance of gender in groups after randomization (68% of the males were in the placebo group). While we found no significant interaction between sex and group on the outcome after adjusting for baseline PSS, larger studies with groups stratified for gender may be required to further confirm these findings. Conclusion: This study demonstrated that 2. 2 g/day of EPA for 12 weeks did not reduce chronic psychological stress

Tuning the magnetic ground state of a novel tetranuclear Nickel(II) molecular complex by high magnetic fields

Electron spin resonance and magnetization data in magnetic fields up to 55 T of a novel multicenter paramagnetic molecular complex [L_2Ni_4(N_3)(O_2C Ada)_4](Cl O_4) are reported. In this compound, four Ni centers each having a spin S = 1 are coupled in a single molecule via bridging ligands (including a \mu_4-azide) which provide paths for magnetic exchange. Analysis of the frequency and temperature dependence of the ESR signals yields the relevant parameters of the spin Hamiltonian, in particular the single ion anisotropy gap and the g factor, which enables the calculation of the complex energy spectrum of the spin states in a magnetic field. The experimental results give compelling evidence for tuning the ground state of the molecule by magnetic field from a nonmagnetic state at small fields to a magnetic one in strong fields owing to the spin level crossing at a field of ~25 T.Comment: revised version, accepted for publication in Physical Review

Pol II Docking and Pausing at Growth and Stress Genes in C. elegans

Fluctuations in nutrient availability profoundly impact gene expression. Previous work revealed postrecruitment regulation of RNA polymerase II (Pol II) during starvation and recovery in Caenorhabditis elegans, suggesting that promoter-proximal pausing promotes rapid response to feeding. To test this hypothesis, we measured Pol II elongation genome wide by two complementary approaches and analyzed elongation in conjunction with Pol II binding and expression. We confirmed bona fide pausing during starvation and also discovered Pol II docking. Pausing occurs at active stress-response genes that become downregulated in response to feeding. In contrast, “docked” Pol II accumulates without initiating upstream of inactive growth genes that become rapidly upregulated upon feeding. Beyond differences in function and expression, these two sets of genes have different core promoter motifs, suggesting alternative transcriptional machinery. Our work suggests that growth and stress genes are both regulated postrecruitment during starvation but at initiation and elongation, respectively, coordinating gene expression with nutrient availability

A new approach to construct pathway connected networks and its application in dose responsive gene expression profiles of rat liver regulated by 2,4DNT

<p>Abstract</p> <p>Background</p> <p>Military and industrial activities have lead to reported release of 2,4-dinitrotoluene (2,4DNT) into soil, groundwater or surface water. It has been reported that 2,4DNT can induce toxic effects on humans and other organisms. However the mechanism of 2,4DNT induced toxicity is still unclear. Although a series of methods for gene network construction have been developed, few instances of applying such technology to generate pathway connected networks have been reported.</p> <p>Results</p> <p>Microarray analyses were conducted using liver tissue of rats collected 24h after exposure to a single oral gavage with one of five concentrations of 2,4DNT. We observed a strong dose response of differentially expressed genes after 2,4DNT treatment. The most affected pathways included: long term depression, breast cancer regulation by stathmin1, WNT Signaling; and PI3K signaling pathways. In addition, we propose a new approach to construct pathway connected networks regulated by 2,4DNT. We also observed clear dose response pathway networks regulated by 2,4DNT.</p> <p>Conclusions</p> <p>We developed a new method for constructing pathway connected networks. This new method was successfully applied to microarray data from liver tissue of 2,4DNT exposed animals and resulted in the identification of unique dose responsive biomarkers in regards to affected pathways.</p

Synthesis and preliminary biological evaluation of a novel P2X7R radioligand [18F]IUR-1601

The reference standard IUR-1601 ((S)-N-(2-chloro-3-(trifluoromethyl)benzyl)-1-(2-fluoroethyl)-5-oxopyrrolidine-2-carboxamide) was synthesized from tert-butyl (S)-5-oxopyrrolidine-2-carboxylate, fluoroethylbromide, and 2-chloro-3-(trifluoromethyl)benzylamine with overall chemical yield 12% in three steps. The target tracer [18F]IUR-1601 ((S)-N-(2-chloro-3-(trifluoromethyl)benzyl)-1-(2-[18F]fluoroethyl)-5-oxopyrrolidine-2-carboxamide) was synthesized from desmethyl-GSK1482160 with 2-[18F]fluoroethyl tosylate, prepared from 1,2-ethylene glycol-bis-tosylate and K[18F]F/Kryptofix2.2.2, in two steps and isolated by HPLC combined with SPE in 1–3% decay corrected radiochemical yield. The radiochemical purity was >99%, and the molar activity at end of bombardment (EOB) was 74–370 GBq/μmol. The potency of IUR-1601 in comparison with GSK1482160 was determined by a radioligand competitive binding assay using [11C]GSK1482160, and the binding affinity Ki values for IUR-1601 and GSK1482160 are 4.31 and 5.14 nM, respectively

Synthesis and initial in vitro characterization of a new P2X7R radioligand [18F]IUR-1602

The overexpression of P2X7R is associated with neuroinflammation and plays an important role in various neurodegenerative diseases. The [18F]fluoropropyl derivative of GSK1482160, [18F]IUR-1602, has been first prepared and examined as a new potential P2X7R radioligand. The reference standard IUR-1602 was synthesized from tert-butyl (S)-5-oxopyrrolidine-2-carboxylate, fluoropropylbromide, and 2-chloro-3-(trifluoromethyl)benzylamine with overall chemical yield 13% in three steps. The target tracer [18F]IUR-1602 was synthesized from desmethyl-GSK1482160 with 3-[18F]fluoropropyl tosylate, prepared from propane-1,3-diyl bis(4-methylbenzenesulfonate) and K[18F]F/Kryptofix2.2.2, in two steps and isolated by HPLC combined with SPE in 2–7% decay corrected radiochemical yield. The radiochemical purity was >99%, and the molar activity at end of bombardment (EOB) was 74–370 GBq/μmol. The potency of IUR-1602 in comparison with GSK1482160 was determined by a radioligand competitive binding assay using [11C]GSK1482160, and the binding affinity Ki values for IUR-1602 and GSK1482160 are 23.6 and 3.07 nM, respectively. The initial in vitro evaluation results, 8-fold less potency of [18F]IUR-1602 compared to [11C]GSK1482160, prevent further in vivo evaluation of [18F]IUR-1602 in animals and human

The MURALES survey. VI. Properties and origin of the extended line emission structures in radio galaxies

This is the sixth paper presenting the results of the MUse RAdio Loud Emission line Snapshot survey (MURALES). We observed 37 radio sources from the 3C sample with z<0.3 and declination <20 degrees with the MUSE optical integral field spectrograph at the VLT. We here focus on the properties of the extended emission line regions (EELRs) that can be studied with unprecedented detail thanks to the depth of these observations. Line emission in the 10 FRIs is, in most cases, confined to within 4 kpc) ionized gas is seen in all but two of the 26 FRIIs. It usually takes the form of elongated or filamentary structures, typically extending between 10 and 30 kpc, but also reaching distances of ~80 kpc. We find that 1) the large-scale ionized gas structures show a tendency to be oriented at large angles from the radio axis, and 2) the gas on a scale of a few kpc from the nucleus often shows ordered rotation with a kinematical axis forming a median angle of 65 degrees with the radio axis. We also discuss the velocity field and ionization properties of the EELRs. The observed emission line structures appear to be associated with gaseous "superdisks" formed after a gas rich merger. The different properties of the EELR can be explained with a combination of the source evolutionary state and the orientation of the "superdisk" with respect to the radio axis. The general alignment between the superdisks and radio axis might be produced by stable and coherent accretion maintained over long timescales.Comment: Pre-proofs version - Accepted for publication in A&