Light adaptation increases response latency of alpha ganglion cells via a threshold-like nonlinearity

Adaptation is an important process of sensory systems to adjust sensitivity to ensure the appropriate information encoding. Sensitivity and kinetics of retinal ganglion cell (RGC) responses have been studied extensively using a brief flash superimposed on different but steady backgrounds. However, it is still unclear if light adaptation exerts any effect on more complex response properties, such as response nonlinearity. In this study, we found that the latency of spike responses to a repeated flashing spot stimulation increased by 30 ms in the mouse ON α RGCs (An ON-type RGC is excited when a spot is turned on in the center of its receptive field). A single dimming event preceding the test flash on a steady adapting background could also produce similar effect in increasing latency of light responses. A simple computational model with a linear transformation of the light stimulus and a threshold-like nonlinearity could account for the experimental data. Moreover, the strength of the measured nonlinearity and the response latency were affected by the duration of light adaptation. The possible biological processes underlying this nonlinearity were explored. Voltage clamp recording revealed the presence of the increase in latency and threshold-like nonlinearity in the excitatory input of RGCs. However, no comparable nonlinearity was observed in the light responses of the ON cone bipolar cells. We further excluded GABAergic and glycinergic inhibition, N-methyl-D-aspartate receptor rectification and voltage-gated Na(+) channels as potential sources of this nonlinearity by pharmacological experiments. Our results indicate the bipolar cell terminals as the potential site of nonlinearity. Computational modeling constrained by experimental data supports that conclusion and suggests the voltage-sensitive Ca(++) channels and Ca(++)-dependent vesicle release in the bipolar cell terminals as mechanistic basis.

Changing coupling pattern of The ON-OFF direction-selective ganglion cells in early postnatal mouse retina

In the adult rabbit and mouse retina, about 30% of the ON-OFF direction selective ganglion cells (DSGCs) are coupled via gap junctions. In early postnatal rabbit retinas, a greater proportion of morphological ON-OFF DSGCs shows coupling with a larger number of nearby somas. It is not clear whether the coupled ON-OFF DSGCs belong to the same subtype, or how coupling patterns change during development. In this study, we showed that in adult mouse retinas, all coupled ON-OFF DSGCs exhibited preferred directions (PDs) to superior, and this pattern emerged at postnatal day 15 (P15). At P13, the ON-OFF DSGCs with PDs to posterior were also coupled. Every ON-OFF DSGC in every subtype injected at P12 exhibited coupling. Therefore, a rapid decoupling process takes place in DSGCs around eye opening. Light deprivation delayed but did not halt the decoupling process. By using a transgenic mouse line in which green fluorescent protein (GFP) is selectively expressed in DSGCs with PDs to posterior and by performing in situ hybridization of cadherin-6, a marker for the DSGCs with PDs to superior and inferior, we showed that heterologous coupling existed between DSGCs with PDs to anterior and posterior till P12, but this heterologous coupling never spread to DSGCs positive for cadherin-6.

Phase-field-based lattice Boltzmann model for incompressible binary fluid systems with density and viscosity contrasts

A lattice Boltzmann model (LBM) is proposed based on the phase-field theory to simulate incompressible binary fluids with density and viscosity contrasts. Unlike many existing diffuse interface models which are limited to density matched binary fluids, the proposed model is capable of dealing with binary fluids with moderate density ratios. A new strategy for projecting the phase field to the viscosity field is proposed on the basis of the continuity of viscosity flux. The new LBM utilizes two lattice Boltzmann equations (LBEs): one for the interface tracking and the other for solving the hydrodynamic properties. The LBE for interface tracking can recover the Chan-Hilliard equation without any additional terms; while the LBE for hydrodynamic properties can recover the exact form of the divergence-free incompressible Navier-Stokes equations avoiding spurious interfacial forces. A series of 2D and 3D benchmark tests have been conducted for validation, which include a rigid-body rotation, stationary and moving droplets, a spinodal decomposition, a buoyancy-driven bubbly flow, a layered Poiseuille flow, and the Rayleigh-Taylor instability. It is shown that the proposed method can track the interface with high accuracy and stability and can significantly and systematically reduce the parasitic current across the interface. Comparisons with momentum-based models indicate that the newly proposed velocity-based model can better satisfy the incompressible condition in the flow fields, and eliminate or reduce the velocity fluctuations in the higher-pressure-gradient region and, therefore, achieve a better numerical stability. In addition, the test of a layered Poiseuille flow demonstrates that the proposed scheme for mixture viscosity performs significantly better than the traditional mixture viscosity methods.

Prospective feasibility study on the use of multiband mucosectomy for endoscopic resection of early squamous neoplasia in the esophagus

BACKGROUND AND STUDY AIMS

Endoscopic resection for esophageal squamous high-grade intraepithelial neoplasia (HGIN) or intramucosal cancer (esophageal squamous cell carcinoma [ESCC]) with the endoscopic resection cap technique is technically difficult, and requires submucosal lifting and multiple snares for piecemeal resections. Multiband mucosectomy (MBM) is an easy-to-use endoscopic resection technique and may be the modality of choice in China, where ESCC is extremely prevalent. The aim of the current study was to prospectively evaluate MBM for piecemeal endoscopic resection of squamous neoplasia of the esophagus.

METHODS

Patients with HGIN/ESCC and no signs of submucosal invasion or metastatic disease were included in the study. Lesions were delineated using electrocoagulation and resected using the MBM technique. Endpoints were procedure time, endoscopic radicality, complications, histology of the endoscopic resection specimens, and absence of HGIN/ESCC at the endoscopic resection scar during follow-up.

RESULTS

A total of 41 patients (26 male; mean age 61 years) underwent MBM; all lesions were visible with white light endoscopy (median length 5 cm, interquartile range [IQR] 4 - 6 cm; median circumferential extent 42 %, IQR 25 - 50 %). Median procedure time was 12 minutes (IQR 8 - 24 minutes). Median number of resections was 5 (IQR 3 - 6). Endoscopic complete resection was achieved in all lesions. There was one perforation, which was treated by application of clips. No other complications were observed. The worst histology was ESCC (n = 19), HGIN (n = 17), middle grade intraepithelial neoplasia (n = 4), and normal squamous epithelium (n = 1). Endoscopic follow-up at 3 months showed HGIN at the endoscopic resection scar in two patients, which was effectively treated endoscopically, and showed normal squamous epithelium in all patients at final follow-up (median 15 months, IQR 12 - 24 months).

CONCLUSION

This first prospective study on MBM for piecemeal endoscopic resection of early esophageal squamous neoplasia showed that MBM was effective for the complete removal of lesions with short procedure time, few complications, effective histological assessment of resected specimens, and durable treatment effect.

A comparative study of two kinds of small bowel cleaning score system for capsule endoscopy

AIM

The study is aim to compare two kinds of cleaning score system for capsule endoscopy, with a view of these two cleaning score system can help to evaluate small bowel cleanliness.

METHODS

Three readers evaluated these two cleaning score system by assessing the inter-observer, intra-patient, and intraobserver agreement.

RESULTS

The assessment of the reliability and concordance, inter-observer agreement and intra-patient agreement of System1 and System2 was excellent with the intraclass correlation coefficient (ICC) values of 0.873, 0.821, 0.863 and 0.772. The data regarding the assessment on intra-observer agreement and intrapatient agreement of System1 and System2 were available and the results were also excellent with ICC values of 0.887, 0.846, 0.870 and 0.809. The overall adequacy assessment of System1 and System2, there was no significant difference among the three readers of inter-observer agreement (X2 = 0.051, P = 0.822, X2 = 0.085, P = 0.081, X2 = 0.048, P = 0.827) and intra- patient agreement (X2 = 0.196, P = 0.658, X2 = 0.208, P = 0.648, X2 = 0.054, P = 0.817), neither was intra-observer agreement (X2 = 0.208, P = 0.648, X2 = 0.223, P = 0.637, X2 = 0.484, P = 0.487) and intrapatient agreement (X2 = 0.054, P = 0.817, X2 = 0.054, P = 0.817, X2 = 0519, P = 0.471).

CONCLUSION

The two system both are simple, operable, and can be used in clinical practice.

The onion skin-like organization of the septum arises from multiple embryonic origins to form multiple adult neuronal fates

In the past several decades, tremendous progress has been achieved through developmental studies of the central nervous system structures such as the cerebral cortex. The septum, which receives reciprocal connections from a variety of brain structures, contains diverse projection neurons but few interneurons. However, the mechanisms underlying its development remain poorly understood. Here we show that the septum is organized into an onion skin-like structure composed of five groups of neurons. These neurons are parvalbumin, choline acetyltransferase, neuronal nitric oxide synthase, calretinin and calbindin immunoreactive. Using the BrdU birth-dating method, we found that these five groups of neurons in the septum are grossly generated following an outside-in pattern. Interestingly, the distinct molecular identities of these neuronal subtypes correspond to their heterogeneous subpallial origins. Using three specific transgenic mouse lines and focal in utero electroporation of Cre-reporter plasmid, we showed that septal neurons originate from not only local progenitor regions but also neighboring progenitor regions including the medial ganglionic eminence and preoptic area. Thus, the neuronal diversity of the septum is achieved through both temporal and spatial control. Our results also suggest that multiple neuronal subtypes arrive to the septum through both radial and tangential migration. Based on these findings, we proposed a novel developmental model involving multiple spatial-temporal origins of septal neurons. This study presents new perspectives for comprehensively exploring septal functions in brain circuits.

'Green'-synthesized near-infrared PbS quantum dots with silica-PEG dual-layer coating: ultrastable and biocompatible optical probes for in vivo animal imaging

In this paper, PbS semiconductor quantum dots (QDs) with near-infrared (NIR) photoluminescence were synthesized in oleic acid and paraffin liquid mixture by using an easily handled and 'green' approach. Surface functionalization of the QDs was accomplished with a silica and polyethylene glycol (PEG) phospholipid dual-layer coating and the excellent chemical stability of the nanoparticles is demonstrated. We then successfully applied the ultrastable PbS QDs to in vivo sentinel lymph node (SLN) mapping of mice. Histological analyses were also carried out to ensure that the intravenously injected nanoparticles did not produce any toxicity to the organism of mice. These experimental results suggested that our ultrastable NIR PbS QDs can serve as biocompatible and efficient probes for in vivo optical bioimaging and has great potentials for disease diagnosis and clinical therapies in the future.

A novel allergen Tab y 1 with inhibitory activity of platelet aggregation from salivary glands of horseflies

BACKGROUND

Horsefly sting causes allergic reactions in human body. However, our knowledge on horsefly allergens remains poor.

OBJECTIVES

To identify the novel horsefly allergens and characterize their properties.

METHODS

A native allergen protein Tab y 1 (apyrase) was purified from the salivary glands of the horsefly Tabanus yao Macquart by gel filtration and ion exchange chromatography. Its sequence was determined by Edman degradation and cDNA cloning. Its allergenicity was assessed by immunoblotting for specific IgE, basophil activation test, skin prick test (SPT), and competitive enzyme-linked immunosorbent assay (ELISA).

RESULTS

Tab y 1 showed a single diffusion band of 70 kDa on SDS-PAGE. Seventy percent (7/10) of patients with horsefly allergy tested positive to Tab y 1 in SPT; sera from 81% (30/37) of patients reacted to Tab y 1 on western blots. Purified Tab y 1 reduced approximately 42% sera IgE reactivity to horsefly salivary gland extract on a competitive ELISA. Tab y 1 upregulated the expression of CD63 and CCR3 on passively sensitized basophils by up to approximately 4.9-fold. Tab y 1 also showed enzymatic activity to hydrolyze ATP and ADP, and potent antiplatelet aggregation and antithrombotic activities.

CONCLUSION

The current work identified a novel major allergen of horsefly, Tab y 1, with antiplatelet aggregation and antithrombotic activities, which implicates Tab y 1 in helping horseflies suck host blood, meanwhile causing allergy in their human hosts.

Cloning, molecular characterization and heterologous expression of a glutathione S-transferase gene in rice

OsGSTL2 is one of three tandem-arranged glutathione S-transferase, lambda class genes in chromosome 3 of rice (Oryza sativa L.). It includes 9 introns and 10 exons, and encodes a protein of 244 amino acid residues with a calculated molecular mass of 27.37 kDa. The predicted three-dimensional structure of OsGSTL2 showed a typical glutathione S-transferase fold. Using semi-quantitative RT-PCR analysis, OsGSTL2 transcript was detected in the roots and leaves of seedling stage and tillering stage, and the roots, leaves and panicles of heading stage from rice plants, and the expression level of OsGSTL2 mRNA in rice roots show significant change under chlorsulfuron stress. The OsGSTL2 gene was cloned into pYTV vector and was transformed into yeast strain PEP4. Western blot analysis showed the exogenous OsGSTL2 was expressed in transformed yeast. GST activity of crude extracts of yeast showed the OsGSTL2 transgenic yeast had higher levels of GST activities than control yeasts. These findings suggested that the OsGSTL2 is a glutathione S-transferase and has potential use in detoxification.

Analysis of properties and proinflammatory functions of cockroach allergens Per a 1.01s

Cockroaches have been identified as one of the major indoor allergens inducing perennial rhinitis and asthma. Per a 1s are a group of the major allergens from American cockroach. Although Per a 1s are major allergens from American cockroach, factors contributing to the allergenicity of Per a 1s are still poorly defined. To investigate the effects of Per a 1s on the expression of PARs and the release of proinflammatory cytokines from mast cells. Per a 1.0101 and Per a 1.0104 were cloned from American cockroach and then expressed in Eschericia coli. The purified allergens were used to stimulate P815 mast cells, and the expression of protease-activated receptors (PARs) was determined by real-time RT-PCR and flow cytometry. The levels of IL-4 and IL-13 in culture media were detected with ELISA. Sera from 80 and 77.3% of cockroach allergy patients reacted to recombinant Per a (rPer a) 1.0101 and rPer a 1.0104, confirming they are major allergens. Both rPer a 1.0101 and rPer a 1.0104 had no enzymatic activity, but rPer a 1.0101 upregulated the expression of PAR-1 and PAR-2, and rPer a 1.0104 enhanced the expression of PAR-1 and PAR-4 proteins. Both recombinant allergens were able to increase the release of IL-4 and IL-13 from P815 mast cells. This is the first study aiming to investigate functions of group 1 allergens of American cockroach. rPer a 1.0101 and rPer a 1.0104 have the capacity to upregulate the expression of PARs and to enhance Th2 cytokine production in mast cells.

Left-lateralized N170 response to unpronounceable pseudo but not false Chinese characters-the key role of orthography

A negative event-related potential (ERP) component, known as N170, can be readily recorded over the posterior left brain region when skilled readers are presented with visual words. This left-lateralized word-related N170 has been attributed either to linguistic processes, particularly phonological processing, or to the role of orthographic regularity, emphasizing a perceptual origin. This debate, however, is difficult to resolve in the context of alphabetic scripts because of the tight relations between orthography and phonology. In contrast, Chinese characters have arbitrary mappings between orthographic and sound forms, making it possible to tease apart these two properties of visual words. We therefore addressed this issue by examining ERP responses to Chinese characters and three types of structurally matched but unpronounceable stimuli: pseudo-characters, false-characters, and stroke combinations. A content-irrelevant color matching task was adopted to minimize potentially different top-down modulations across stimulus types. Results show that, relative to false-characters and stroke combinations, real- and pseudo-characters evoked greater N170 in the left posterior brain region. Critically, despite being unpronounceable, pseudo-characters produced the same amplitude and left-lateralized N170, just as real-characters. These results provide strong evidence that orthography rather than phonology serves as the main driver for the enhanced and left-lateralized N170 to visual words.

Development of an image-based model for capillary vasculature of retina

The paper presents a method of development of a detailed network model to represent retinal capillary vasculature. The capillary model is a circular mesh consisting of concentric rings with an increasing diameter. Each of the rings has uniformly distributed bifurcation nodes to represent capillary vessels. The model is customized using the data that has been measured from confocal microscopic images of a mouse retina. The capillary model developed can be connected to networks of larger vessels of the vasculature such as arterial and venous networks to form a complete model of the retinal network. A method to automate such interface connections between capillary and other vascular networks using connecting vessels (i.e., pre-capillary and post-capillary) is also presented in the paper. Such a detailed image-based capillary model together with the arterial and venular networks can be used for various circulation simulations to obtain accurate information on hemodynamic quantities such as the spatial distribution of pressure and flow in the vasculature for both physiological and pathological conditions. The method presented for the development of the capillary model can also be adopted for vasculatures of other organs.

CD14+ cell-derived IL-29 modulates proinflammatory cytokine production in patients with allergic airway inflammation

BACKGROUND

  Interleukin (IL)-29 is a newly described cytokine that has anti-viral activity, induces tumor cell death and regulates immune function. Whether it plays a role in immune disorders is unclear. This study aims to examine the role of IL-29 in the modulation of immune response under allergic environment.

METHODS

  A group of patients with allergic asthma or/and allergic rhinitis was recruited to this study. Serum samples were collected from the patients in both in-season and out-season; the serum levels of IL-29 were determined by enzyme-linked immunoassay. Cell types of IL-29-producing cells in upper airway mucosa were identified with immune staining and examined by immunohistochemistry and flow cytometry.

RESULTS

  High serum levels of IL-29 were detected in patients with allergic asthma in in-season, but not in out-season. The majority of IL-29(+) cells in upper airway tissue were CD14(+) cells. Exposure to specific antigens triggered the release of IL-4 from antigen-specific CD4(+) T cells; the released IL-4 activated CD14(+) cells to release IL-29; the released IL-29 further triggered the release of IL-6 and tumor necrosis factor from CD4(+) T cells.

CONCLUSIONS

  Interleukin-29 is involved in the pathogenesis of allergic inflammation via modulating immune cells' function to release proinflammatory cytokines.

Maturation of neurotransmission in the developing rat cochlea: immunohistochemical evidence from differential expression of synaptophysin and synaptobrevin 2

Synaptophysin and synaptobrevin 2 associate closely with packaging and storage of synaptic vesicles and transmitter release, and both play important roles in the development of rat cochlea. We examined the differential expression of synaptophysin and synaptobrevin 2 in the developing Sprague-Dawley rat cochlea, and investigated the relationship between their expression and auditory development. The expression of synaptophysin and synaptobrevin 2 was not observed in Kolliker's and Corti's organ at postnatal 1 day (P1) and P5, and the top turn of the cochlea at P10. Expression was detected in the outer spiral bundle (OSB), the inner spiral bundle (ISB), and the medial wall of the Deiters' cell of the cochlea at P14, and P28, and in the middle or the basal turn of Corti's organ at P10. Synaptobrevin 2 was expressed in the top of the inner hair cells (IHCs) in Corti's organ of both P14 and P28 rats. All spiral ganglion neurons (SGNs) were stained at all ages examined. The localization of synaptophysin and synaptobrevin 2 in the cochlea was closely associated with the distribution of nerve fibers and neural activity (the docking and release of synaptic vesicles). Synaptophysin and synaptobrevin 2 were expressed in a dynamic manner during the development of rat cochlea. Their expression differences during the development were in favor of the configuration course constructed between nerve endings and target cells. It also played a key role in the formation of the correct coding of auditory information during auditory system development.