^{7}Be(n,α)^{4}He Reaction and the Cosmological Lithium Problem: Measurement of the Cross Section in a Wide Energy Range at n_TOF at CERN

The energy-dependent cross section of the ^{7}Be(n,α)^{4}He reaction, of interest for the so-called cosmological lithium problem in big bang nucleosynthesis, has been measured for the first time from 10 meV to 10 keV neutron energy. The challenges posed by the short half-life of ^{7}Be and by the low reaction cross section have been overcome at n_TOF thanks to an unprecedented combination of the extremely high luminosity and good resolution of the neutron beam in the new experimental area (EAR2) of the n_TOF facility at CERN, the availability of a sufficient amount of chemically pure ^{7}Be, and a specifically designed experimental setup. Coincidences between the two alpha particles have been recorded in two Si-^{7}Be-Si arrays placed directly in the neutron beam. The present results are consistent, at thermal neutron energy, with the only previous measurement performed in the 1960s at a nuclear reactor. The energy dependence reported here clearly indicates the inadequacy of the cross section estimates currently used in BBN calculations. Although new measurements at higher neutron energy may still be needed, the n_TOF results hint at a minor role of this reaction in BBN, leaving the long-standing cosmological lithium problem unsolved.

Liver Resident Macrophages (Kupffer Cells) Share Several Functional Antigens in Common with Endothelial Cells

The identification and specific functions of Kupffer cells (KCs), a liver resident macrophage subpopulation, are still unclear. We compared KCs with peritoneal macrophages using cDNA microarray analysis and found that these cells share some antigens with endothelial cells. KCs highly express VCAM-1 and VEGF receptors (VEGF-Rs) at transcriptional and protein levels. VCAM-1 mediates the functional binding of KCs with lymphocytes and induces KC activation. Among the VEGF receptors, VEGF-R2 and VEGF-R3 were expressed on the KCs, while VEGF-R1 was expressed on other tissue macrophage subsets. VEGF120, a ligand of both VEGF-R1 and VEGF-R2, transduced strong survival and chemotactic signals through the KCs, when compared to PIGF, a VEGF-R1 ligand, indicating that VEGF-R2 plays significant roles in regulating KC activities. Expression of the VEGF-Rs was regulated by TLR4 signalling. These results suggest that the function of KCs is partly regulated by the common antigens shared with endothelial cells.

Repeated forced swim stress prior to complete Freund's adjuvant injection enhances mechanical hyperalgesia and attenuates the expression of pCREB and ΔFosB and the acetylation of histone H3 in the insular cortex of rat

Exposure to stressors causes substantial effects on the perception and response to pain. In several animal models, chronic stress produces hyperalgesia. The insular (IC) and anterior cingulate cortices (ACC) are the regions exhibiting most reliable pain-related activity. And the IC and ACC play an important role in pain modulation via descending pain modulatory system. In the present study we examined the expression of phospho-cAMP response element-binding protein (pCREB) and ΔFosB and the acetylation of histone H3 in the IC and ACC after forced swim stress (FS) and complete Freund's adjuvant (CFA) injection to clarify changes in the cerebral cortices that affect the activity of the descending pain modulatory system in rats with stress-induced hyperalgesia. CFA injection into the hindpaw or FS (day 1, 10min; days 2-3, 20min) induced a significant increase in the expression of pCREB and ΔFosB and the acetylation of histone H3 in the IC. Quantitative image analysis showed that the numbers of ΔFosB-immunoreactivity (IR) cells in the bilateral anterior and posterior IC (AIC and PIC) were significantly higher in the CFA group (AIC R, 548.0±98.6; AIC L, 433.5±89.4; PIC R, 546.1±72.8; PIC L, 415.5±53.5) than those in the naive group (AIC R, 86.6±14.8; AIC L, 85.5±24.7; PIC R, 124.5±29.9; PIC L, 107.0±19.8, p<0.01). However the FS prior to the CFA injection enhanced the mechanical hyperalgesia and attenuated the expression of pCREB and ΔFosB and the acetylation of histone H3 in the IC. There was no significant difference in the numbers of ΔFosB-IR cells in the bilateral PIC between the FS+CFA and naive groups. These findings suggest neuroplasticity in the IC after the FS, which may be involved in the enhancement of CFA-induced mechanical hyperalgesia through dysfunction of the descending pain modulatory system.

Spermidine promotes retinal ganglion cell survival and optic nerve regeneration in adult mice following optic nerve injury

Spermidine acts as an endogenous free radical scavenger and inhibits the action of reactive oxygen species. In this study, we examined the effects of spermidine on retinal ganglion cell (RGC) death in a mouse model of optic nerve injury (ONI). Daily ingestion of spermidine reduced RGC death following ONI and sequential in vivo retinal imaging revealed that spermidine effectively prevented retinal degeneration. Apoptosis signal-regulating kinase-1 (ASK1) is an evolutionarily conserved mitogen-activated protein kinase kinase kinase and has an important role in ONI-induced RGC apoptosis. We demonstrated that spermidine suppresses ONI-induced activation of the ASK1-p38 mitogen-activated protein kinase pathway. Moreover, production of chemokines important for microglia recruitment was decreased with spermidine treatment and, consequently, accumulation of retinal microglia is reduced. In addition, the ONI-induced expression of inducible nitric oxide synthase in the retina was inhibited with spermidine treatment, particularly in microglia. Furthermore, daily spermidine intake enhanced optic nerve regeneration in vivo. Our findings indicate that spermidine stimulates neuroprotection as well as neuroregeneration, and may be useful for treatment of various neurodegenerative diseases including glaucoma.

Dock3 protects myelin in the cuprizone model for demyelination

Dedicator of cytokinesis 3 (Dock3) belongs to an atypical family of the guanine nucleotide exchange factors. It is predominantly expressed in the neural tissues and causes cellular morphological changes by activating the small GTPase Rac1. We previously reported that Dock3 overexpression protects retinal ganglion cells from excitotoxic cell death. Oligodendrocytes are the myelinating cells of axons in the central nervous system and these cells are damaged in demyelinating disorders including multiple sclerosis (MS) and optic neuritis. In this study, we examined if Dock3 is expressed in oligodendrocytes and if increasing Dock3 signals can suppress demyelination in a cuprizone-induced demyelination model, an animal model of MS. We demonstrate that Dock3 is expressed in oligodendrocytes and Dock3 overexpression protects myelin in the corpus callosum following cuprizone treatment. Furthermore, we show that cuprizone demyelinates optic nerves and the extent of demyelination is ameliorated in mice overexpressing Dock3. Cuprizone treatment impairs visual function, which was demonstrated by multifocal electroretinograms, an established non-invasive method, and Dock3 overexpression prevented this effect. In mice overexpressing Dock3, Erk activation is increased, suggesting this may at least partly explain the observed protective effects. Our findings suggest that Dock3 may be a therapeutic target for demyelinating disorders including optic neuritis.

Brimonidine prevents neurodegeneration in a mouse model of normal tension glaucoma

Glaucoma is one of the leading causes of irreversible blindness that is characterized by progressive degeneration of optic nerves and retinal ganglion cells (RGCs). In the mammalian retina, excitatory amino-acid carrier 1 (EAAC1) is expressed in neural cells, including RGCs, and the loss of EAAC1 leads to RGC degeneration without elevated intraocular pressure (IOP). Brimonidine (BMD) is an α2-adrenergic receptor agonist and it is commonly used in a form of eye drops to lower IOP in glaucoma patients. Recent studies have suggested that BMD has direct protective effects on RGCs involving IOP-independent mechanisms, but it is still controversial. In the present study, we examined the effects of BMD in EAAC1-deficient (KO) mice, an animal model of normal tension glaucoma. BMD caused a small decrease in IOP, but sequential in vivo retinal imaging and electrophysiological analysis revealed that treatment with BMD was highly effective for RGC protection in EAAC1 KO mice. BMD suppressed the phosphorylation of the N-methyl-D-aspartate receptor 2B (NR2B) subunit in RGCs in EAAC1 KO mice. Furthermore, in cultured Müller glia, BMD stimulated the production of several neurotrophic factors that enhance RGC survival. These results suggest that, in addition to lowering IOP, BMD prevents glaucomatous retinal degeneration by stimulating multiple pathways including glia–neuron interactions.

Characterization of Membrane-bound Spermidine Dehydrogenase ofCitrobacter freundii

Spermidine dehydrogenase found in the membrane fraction of Citrobacter freundii IFO 12681 was solubilized with Triton X-100 and further purified to homogeneity. The properties of the membrane enzyme were almost identical to those obtained from the soluble fraction of the organism with respect to molecular and catalytic properties. Thus, binding properties of the enzyme to the bacterial membrane were checked. The ratio of enzyme activity found in the soluble fraction to the membrane fraction was dependent on salt concentration during cell disruption. A hydrophobic interaction was largely involved in anchoring the enzyme to the membrane fraction. Purified spermidine dehydrogenase from the soluble fraction was readily adsorbed into the membrane fraction in the presence of salt. Spermidine dehydrogenase appeared to be a membrane-bound enzyme localized in the cytoplasmic membranes in a manner that makes a partial release of the enzyme possible during mechanical cell disruption. When spermidine oxidation was done with the resting cells of C. freundii, a stoichiometric formation of two reaction products, 1,3-diaminopropane and gamma-aminobutyraldeyde, was observed without any lag time. These facts indicate that the enzyme is localized on the outer surface of the cytoplasmic membranes or in the periplasmic space of the organism.

Common variant in VEGFA and response to anti-VEGF therapy for neovascular age-related macular degeneration

Age-related macular degeneration (AMD) is a leading cause of visual impairment in aging populations in industrialized countries. Here we investigated whether the genotype of vascular endothelial growth factor A (VEGFA) gene is associated with response to anti-VEGF therapy. 223 eyes with neovascular AMD were treated with intravitreal anti-VEGF therapy. Responders were defined as patients who had an improvement in best corrected visual acuity (BCVA) of at least 5 letters or one line on the EDTRS visual acuity chart along with resolution of intraretinal or subretinal fluid over 12 months. Patients who did not meet the definition of responders were classified as poor-responders. The vision of responders (n = 148) improved while the vision of poor-responders (n = 75) worsened (P<0.001). Responders on average had a decrease in central foveal thickness (CFT), while poor-responders had an increase in CFT (P <0.001). Compared with the responder group, the poor-responder group had a higher frequency of the risk (T) allele (Allelic P = 0.019) and TT genotype (P = 0.002 under a recessive model) for the VEGFA-rs943080 polymorphism. VEGFA expression was 1.8-fold higher in cells with the VEGFA rs943080 TT genotype than in cells with the VEGFA rs943080 CC genotype (P = 0.012). Age, gender, smoking, diabetes mellitus, and hypertension did not play a significant role in treatment response, but BMI was found to be significantly different between responders and poorresponders (P = 0.033). In conclusion, we demonstrated a potential pharmacogenetic relationship between the VEGFA gene and treatment response to anti-VEGF therapy.The studies are registered at ClinicalTrials.gov under the identifiers NCT00474695 (http://clinicaltrials. gov/ct2/show/NCT00474695) and NCT01464723 (http://clinicaltrials.gov/ct2/show/NCT01464723).

Repeated forced swim stress enhances CFA-evoked thermal hyperalgesia and affects the expressions of pCREB and c-Fos in the insular cortex

Stress affects brain activity and promotes long-term changes in multiple neural systems. Exposure to stressors causes substantial effects on the perception and response to pain. In several animal models, chronic stress produces lasting hyperalgesia. The insular (IC) and anterior cingulate cortices (ACC) are the regions exhibiting most reliable pain-related activity. And the IC and ACC play an important role in pain modulation via the descending pain modulatory system. In the present study we examined the expression of phospho-cAMP response element-binding protein (pCREB) and c-Fos in the IC and ACC after forced swim stress (FS) and complete Freund's adjuvant (CFA) injection to clarify changes in the cerebral cortices that affect the activity of the descending pain modulatory system in the rats with stress-induced hyperalgesia. FS (day 1, 10min; days 2-3, 20min) induced an increase in the expression of pCREB and c-Fos in the anterior IC (AIC). CFA injection into the hindpaw after the FS shows significantly enhanced thermal hyperalgesia and induced a decrease in the expression of c-Fos in the AIC and the posterior IC (PIC). Quantitative image analysis showed that the numbers of c-Fos-immunoreactive neurons in the left AIC and PIC were significantly lower in the FS+CFA group (L AIC, 95.9±6.8; L PIC, 181.9±23.1) than those in the naive group (L AIC, 151.1±19.3, p<0.05; L PIC, 274.2±37.3, p<0.05). These findings suggest a neuroplastic change in the IC after FS, which may be involved in the enhancement of CFA-induced thermal hyperalgesia through dysfunction of the descending pain modulatory system.