Position-independent functional refinement within the vagus motor topographic map.

Motor neurons in the central nervous system often lie in a continuous topographic map, where neurons that innervate different body parts are spatially intermingled. This is the case for the efferent neurons of the vagus nerve, which innervate diverse muscle and organ targets in the head and viscera for brain-body communication. It remains elusive how neighboring motor neurons with different fixed peripheral axon targets develop the separate somatodendritic (input) connectivity they need to generate spatially precise body control. Here we show that vagus motor neurons in the zebrafish indeed generate spatially appropriate peripheral responses to focal sensory stimulation even when they are transplanted into ectopic positions within the topographic map, indicating that circuit refinement occurs after the establishment of coarse topography. Refinement depends on motor neuron synaptic transmission, suggesting that an experience-dependent periphery-to-brain feedback mechanism establishes specific input connectivity amongst intermingled motor populations.

Effect of massive ascites on ramucirumab pharmacokinetics in patients with gastrointestinal cancers: a population pharmacokinetic analysis.

PURPOSE: Considerable amounts of injected immunoglobulin G-based therapeutic monoclonal antibodies, such as ramucirumab, are distributed into ascites. This study aimed to examine the effect of massive ascites on ramucirumab pharmacokinetics in patients with gastrointestinal cancers. METHODS: Population pharmacokinetic analysis of ramucirumab was performed using data on serum ramucirumab concentrations of 52 patients with gastrointestinal cancers, including 8 patients with massive ascites. The Bayesian method using the final population pharmacokinetic model was utilized to estimate trough ramucirumab concentrations after the first dose and at steady state. RESULTS: Population pharmacokinetic analysis revealed that massive ascites as well as body weight were influencing factors for ramucirumab clearance. The estimated ramucirumab clearance was significantly higher in patients with massive ascites than in those with no/mild ascites (0.020 ± 0.004 versus 0.013 ± 0.004 L/h, P < 0.001). The estimated trough ramucirumab concentrations were significantly lower in patients with massive ascites than in those with no/mild ascites after the first dose (26.4 ± 6.8 versus 36.1 ± 7.1 µg/mL, P < 0.001) and at steady state (41.4 ± 16.3 versus 65.9 ± 18.0 µg/mL, P < 0.001). CONCLUSION: In the present study, the presence of massive ascites affected the pharmacokinetics of ramucirumab in patients with gastrointestinal cancers. Our results suggest that dose optimization of ramucirumab may be necessary in patients with massive ascites due to higher ramucirumab clearance.

Distribution of therapeutic monoclonal antibodies into ascites in advanced gastric cancer patients with peritoneal metastasis: case reports and literature review.

BACKGROUND: Therapeutic monoclonal antibodies, including ramucirumab and nivolumab, are used to treat advanced gastric cancer (AGC). Malignant ascites is often accompanied by peritoneal metastasis in AGC patients. However, the distribution of therapeutic monoclonal antibodies into ascites has yet to be adequately investigated. METHODS: We determined serum and ascites concentrations of ramucirumab or nivolumab and total IgG in three AGC patients with massive ascites. When serum and ascites samples were obtained on the same day, the ascites-to-serum ratio (A/S ratio) of the concentration of monoclonal antibodies was evaluated. The relationship between time after last infusion and the A/S ratio of therapeutic monoclonal antibodies was examined using 15 datasets from the present study and the literature. RESULTS: Ramucirumab and nivolumab were detected in massive ascites at considerable amounts (A/S ratios of 0.24-0.35 for ramucirumab and 0.17-0.55 for nivolumab). A positive correlation was detected between the A/S ratios of the therapeutic monoclonal antibodies and the time after last infusion (r = 0.747). Removal of ascites using paracentesis eliminated at least 15.3%-30.3% and 5.2-27.4% of the injected ramucirumab and nivolumab, respectively. Endogenous IgG, as well as therapeutic monoclonal antibodies, were distributed into ascites; the A/S ratios for IgG were 0.22-0.45. CONCLUSION: Our results suggest that therapeutic monoclonal antibodies, including ramucirumab and nivolumab, are distributed into massive ascites in AGC patients concomitantly with endogenous IgG. In these patients, retention of ascites and its removal may result in decreased systemic drug exposure to ramucirumab and nivolumab.

Contribution of Pore-Connectivity to Permeation Performance of Silicalite-1 Membrane; Part I, Pore Volume and Effective Pore Size.

The micropore volumes and effective pore sizes of two types of silicalite-1 membranes were compared with those of a typical silicalite-1 powder. The silicalite-1 membrane with fewer grain boundaries in the membrane layer showed similar micropore volume and effective pores size to those of the silicalite-1 powder. In contrast, when the silicalite-1 membrane contained many grain boundaries, relatively small micropore volume and effective pore size were observed, suggesting that narrowing and obstruction of the micropore would occur along grain boundaries due to the disconnection of the zeolite pore. The silicalite-1 membrane with fewer grain boundaries exhibited relatively high permeation properties for C6-C8 hydrocarbons. There was an over 50-fold difference in benzene permeance between these two types of membranes. We concluded that it is important to reduce grain boundaries and improve pore-connectivity to develop an effective preparation method for obtaining a highly permeable membrane.

Contribution of Pore-Connectivity to Permeation Performance of Silicalite-1 Membrane; Part II, Diffusivity of C6 Hydrocarbon in Micropore.

This study investigated the permeation behaviors of n-hexane and 2-methylpentane through two-types of silicalite-1 membranes that have different pore-connectivity. The permeation mechanisms of these hydrocarbons were able to be explained by the adsorption-diffusion model. In addition, the fluxes through silicalite-1 membranes could be expressed by the modified Fick's first law. The hydrocarbon fluxes through S-1S with better pore-connectivity were ca. 3-20 times larger than those through S-1M with poor pore-connectivity. For these membranes with different pore-connectivity, the activation energy of diffusion of n-hexane was 17.5 kJ mol-1 for the membrane with better pore-connectivity and 18.0 kJ mol-1 for the membrane with poorer pore-connectivity, whereas for 2-methylpentane it was 17.9 and 33.0 kJ mol-1, respectively. We concluded that the pore-connectivity in silicalite-1 membrane significantly influences the molecular diffusivities.

Transport of maternal transthyretin to the fetus in the viviparous teleost Neoditrema ransonnetii (Perciformes, Embiotocidae).

The molecular basis of viviparity in non-mammalian species has not been widely studied. Neoditrema ransonnetii, a surfperch, is a matrotrophic teleost whose fetuses grow by ovarian cavity fluid (OCF) ingestion and by nutrient absorption via their enlarged hindgut. We performed a proteomics analysis of N. ransonnetii plasma protein and found proteins specific to pregnant females; one of these was identified as transthyretin (TTR), a thyroid hormone distributor protein. We synthesized recombinant protein rNrTTR and raised an antibody, anti-rNrTTR, against it. Semi-quantitative analysis by western blotting using the antibody demonstrated that plasma TTR levels were significantly greater in pregnant fish than in non-pregnant fish. OCF and fetal plasma also contained high TTR levels. Immunohistochemical staining showed that large amounts of maternal TTR were taken up by fetal intestinal epithelial cells. These results indicate that maternal TTR is secreted into OCF and taken up by fetal enterocytes, presumably to deliver thyroid hormones to developing fetuses.

Horizontal Boundary Cells, a Special Group of Somitic Cells, Play Crucial Roles in the Formation of Dorsoventral Compartments in Teleost Somite.

Establishment of robust gene expression boundary is crucial for creating elaborate morphology during development. However, mechanisms underlying boundary formation have been extensively studied only in a few model systems. We examined the establishment of zic1/zic4-expression boundary demarcating dorsoventral boundary of the entire trunk of medaka fish (Oryzias latipes) and identified a subgroup of dermomyotomal cells called horizontal boundary cells (HBCs) as crucial players for the boundary formation. Embryological and genetic analyses demonstrated that HBCs play crucial roles in the two major events of the process, i.e., refinement and maintenance. In the refinement, HBCs could serve as a chemical barrier against Wnts from the neural tube by expressing Hhip. At later stages, HBCs participate in the maintenance of the boundary by differentiating into the horizontal myoseptum physically inhibiting cell mixing across the boundary. These findings reveal the mechanisms underlying the dorsoventral boundary in the teleost trunk by specialized boundary cells.

Correlation between Chemical and Physical Pressures on Charge Bistability in [Pd(en)2Br](Suc-Cn)2·H2O.

Hydrostatic (physical) pressure effects on the electrical resistivity of a bromido-bridged palladium compound, [Pd(en)2Br](Suc-C5)2·H2O, were studied. The charge-density-wave to Mott-Hubbard phase transition temperature (TPT) steadily increased with pressure. By a comparison of the effects of the chemical and physical pressures on TPT, it was estimated that the chemical pressure by unit alkyl chain length, i.e., the number of carbon atoms in the alkyl chains within the counterion, corresponded to ca. 1.3 kbar of the physical pressure.

Synthesis and Molecular Structure of a Novel Compound Containing a Carbonate-Bridged Hexacalcium Cluster Cation Assembled on a Trimeric Trititanium(IV)-Substituted Wells-Dawson Polyoxometalate.

A novel compound containing a hexacalcium cluster cation, one carbonate anion, and one calcium cation assembled on a trimeric trititanium(IV)-substituted Wells-Dawson polyoxometalate (POM), [{Ca6(CO3)(µ3-OH)(OH2)18}(P2W15Ti3O61)3Ca(OH2)3]19- (Ca7Ti9Trimer), was obtained as the Na7Ca6 salt (NaCa-Ca7Ti9Trimer) by the reaction of calcium chloride with the monomeric trititanium(IV)-substituted Wells-Dawson POM species "[P2W15Ti3O59(OH)3]9-" (Ti3Monomer). Ti3Monomer was generated in situ under basic conditions from the separately prepared tetrameric species with bridging Ti(OH2)3 groups and an encapsulated Cl- ion, [{P2W15Ti3O59(OH)3}4{µ3-Ti(H2O)3}4Cl]21- (Ti16Tetramer). The Na7Ca6 salt of Ca7Ti9Trimer was characterized by complete elemental analysis, thermogravimetric (TG) and differential thermal analyses (DTA), FTIR, single-crystal X-ray structure analysis, and solution 183W and 31P NMR spectroscopy. X-ray crystallography revealed that the [Ca6(CO3)(µ3-OH)(OH2)18]9+ cluster cation was composed of six calcium cations linked by one µ6-carbonato anion and one µ3-OH- anion. The cluster cation was assembled, together with one calcium ion, on a trimeric species composed of three tri-Ti(IV)-substituted Wells-Dawson subunits linked by Ti-O-Ti bonds. Ca7Ti9Trimer is an unprecedented POM species containing an alkaline-earth-metal cluster cation and is the first example of alkaline-earth-metal ions clustered around a titanium(IV)-substituted POM.

Serotonergic Modulation Enables Pathway-Specific Plasticity in a Developing Sensory Circuit in Drosophila.

How experiences during development cause long-lasting changes in sensory circuits and affect behavior in mature animals are poorly understood. Here we establish a novel system for mechanistic analysis of the plasticity of developing neural circuits by showing that sensory experience during development alters nociceptive behavior and circuit physiology in Drosophila larvae. Despite the convergence of nociceptive and mechanosensory inputs on common second-order neurons (SONs), developmental noxious input modifies transmission from nociceptors to their SONs, but not from mechanosensors to the same SONs, which suggests striking sensory pathway specificity. These SONs activate serotonergic neurons to inhibit nociceptor-to-SON transmission; stimulation of nociceptors during development sensitizes nociceptor presynapses to this feedback inhibition. Our results demonstrate that, unlike associative learning, which involves inputs from two sensory pathways, sensory pathway-specific plasticity in the Drosophila nociceptive circuit is in part established through feedback modulation. This study elucidates a novel mechanism that enables pathway-specific plasticity in sensory systems. VIDEO ABSTRACT.

Potentiation of Methylmercury-Induced Death in Rat Cerebellar Granular Neurons Occurs by Further Decrease of Total Intracellular GSH with BDNF via TrkB in Vitro.

Brain-derived neurotrophic factor (BDNF) is a principal factor for neurogenesis, neurodevelopment and neural survival through a BDNF receptor, tropomyosin-related kinase (Trk) B, while BDNF can also cause a decrease in the intracellular glutathione (GSH) level. We investigated the exacerbation of methylmercury-induced death of rat cerebellar granular neurons (CGNs) by BDNF in vitro. Since methylmercury can decrease intracellular GSH levels, we hypothesized that a further decrease of the intracellular GSH level is involved in the process of the exacerbation of neuronal cell death. In the present study, we established that in CGN culture, a decrease of the intracellular GSH level was further potentiated with BDNF in the process of the methylmercury-induced neuronal death and also in GSH reducer-induced neuronal death. BDNF treatment promoted the decrease in GSH levels induced by methylmercury and also by L-buthionine sulfoximine (BSO) and diethyl maleate (DEM). The promoting effect of BDNF was observed in a TrkB-vector transformant of the rat neuroblastoma B35 cell line but not in the mock-vector transformant. These results indicate that the exacerbating effect of BDNF on methylmercury-induced neuronal death in cultures of CGNs includes a further decrease of intracellular GSH levels, for which TrkB is essential.

Fine-scale topography in sensory systems: insights from Drosophila and vertebrates.

To encode the positions of sensory stimuli, sensory circuits form topographic maps in the central nervous system through specific point-to-point connections between pre- and postsynaptic neurons. In vertebrate visual systems, the establishment of topographic maps involves the formation of a coarse topography followed by that of fine-scale topography that distinguishes the axon terminals of neighboring neurons. It is known that intrinsic differences in the form of broad gradients of guidance molecules instruct coarse topography while neuronal activity is required for fine-scale topography. On the other hand, studies in the Drosophila visual system have shown that intrinsic differences in cell adhesion among the axon terminals of neighboring neurons instruct the fine-scale topography. Recent studies on activity-dependent topography in the Drosophila somatosensory system have revealed a role of neuronal activity in creating molecular differences among sensory neurons for establishing fine-scale topography, implicating a conserved principle. Here we review the findings in both Drosophila and vertebrates and propose an integrated model for fine-scale topography.

Trim9 regulates activity-dependent fine-scale topography in Drosophila.

Topographic projection of afferent terminals into 2D maps in the CNS is a general strategy used by the nervous system to encode the locations of sensory stimuli. In vertebrates, it is known that although guidance cues are critical for establishing a coarse topographic map, neural activity directs fine-scale topography between adjacent afferent terminals [1-4]. However, the molecular mechanism underlying activity-dependent regulation of fine-scale topography is poorly understood. Molecular analysis of the spatial relationship between adjacent afferent terminals requires reliable localization of the presynaptic terminals of single neurons as well as genetic manipulations with single-cell resolution in vivo. Although both requirements can potentially be met in Drosophila melanogaster [5, 6], no activity-dependent topographic system has been identified in flies [7]. Here we report a topographic system that is shaped by neuronal activity in Drosophila. With this system, we found that topographic separation of the presynaptic terminals of adjacent nociceptive neurons requires different levels of Trim9, an evolutionarily conserved signaling molecule [8-11]. Neural activity regulates Trim9 protein levels to direct fine-scale topography of sensory afferents. This study offers both a novel mechanism by which neural activity directs fine-scale topography of axon terminals and a new system to study this process at single-neuron resolution.

Acetylcholine esterase is a regulator of GFAP expression and a target of dichlorvos in astrocytic differentiation of rat glioma C6 cells.

The main target of neurotoxins is neurons because they comprise the main part of neural function, but glial cells may be indirect targets because they support the function of neurons. Among the glial cells, astrocytes in particular act as "nurse cells", regulating neuronal survival and functions. In the present study, to reveal whether a known neurotoxic substance, organophosphate dichlorvos (DDVP), affects the differentiation of astrocytes, we used an astrocyte differentiation model in rat glioma C6 cells. Morphological change and induction of GFAP expression in the differentiating C6 cells were suppressed by DDVP treatment. The known potential targets of DDVP are acetylcholine esterase (AChE), fatty acid amide hydrolase and methyl guanine methyl transferase. Among the specific inhibitors against these enzymes, the AChE inhibitor paraoxon successfully suppressed the cellular morphological changes and the induction of GFAP expression in differentiating C6 cells. These results indicate that DDVP inhibits differentiation in the C6 astrocyte-differentiation model, in which at least AChE inhibition is involved and that AChE is a potent regulator of the differentiation. Furthermore, considering that the main substrate of AChE is ACh, thus, ACh may act as regulators of astrocyte differentiation.

Modular development of the teleost trunk along the dorsoventral axis and zic1/zic4 as selector genes in the dorsal module.

Teleost fish exhibit remarkable diversity in morphology, such as fins and coloration, particularly on the dorsal side. These structures are evolutionary adaptive because their back is highly visible to other individuals. However, owing to the late phenotypic appearance (from larva to adult) and lack of appropriate mutants, the genetic mechanisms that regulate these dorsoventrally asymmetric external patterns are largely unknown. To address this, we have analyzed the spontaneous medaka mutant Double anal fin (Da), which exhibits a mirror-image duplication of the ventral half across the lateral midline from larva to adult. Da is an enhancer mutant for zic1 and zic4 in which their expression in dorsal somites is lost. We show that the dorsoventral polarity in Da somites is lost and then demonstrate using transplantation techniques that somites and their derived tissues globally determine the multiple dorsal-specific characteristics of the body (fin morphology and pigmentation) from embryo to adult. Intriguingly, the zic1/zic4 expression in the wild type persists throughout life in the dorsal parts of somite derivatives, i.e. the myotome, dermis and vertebrae, forming a broad dorsal domain in the trunk. Comparative analysis further implies a central role for zic1/zic4 in morphological diversification of the teleost body. Taken together, we propose that the teleost trunk consists of dorsal/ventral developmental modules and that zic1/zic4 in somites function as selector genes in the dorsal module to regulate multiple dorsal morphologies.

Trunk exoskeleton in teleosts is mesodermal in origin.

The vertebrate mineralized skeleton is known to have first emerged as an exoskeleton that extensively covered the fossil jawless fish. The evolutionary origin of this exoskeleton has long been attributed to the emergence of the neural crest, but experimental evaluation for this is still poor. Here we determine the embryonic origin of scales and fin rays of medaka (teleost trunk exoskeletons) by applying long-term cell labelling methods, and demonstrate that both tissues are mesodermal in origin. Neural crest cells, however, fail to contribute to these tissues. This result suggests that the trunk neural crest has no skeletogenic capability in fish, instead highlighting the dominant role of the mesoderm in the evolution of the trunk skeleton. This further implies that the role of the neural crest in skeletogenesis has been predominant in the cephalic region from the early stage of vertebrate evolution.