Suppressing Structure Delamination for Enhanced Electrochemical Performance of Solid Oxide Cells

Reversible solid oxide cells (rSOCs) have significant potential as efficient energy conversion and storage systems. Nevertheless, the practical application of their conventional air electrodes, such as La0.8Sr0.2MnO3-δ (LSM), Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF), and PrBa0.8Ca0.2Co2O5+δ (PBCC), remains unsatisfactory due to interface delamination during prolonged electrochemical operation. Using micro-focusing X-ray absorption spectroscopy (µ-XAS), a decrease (increase) in the co-valence state from the electrode surface to the electrode/electrolyte interface is observed, leading to the above delamination. Utilizing the one-pot method to incorporate an oxygen-vacancy-enriched CeO2 electrode into these air electrodes, the uniform distribution of the Co valence state is observed, alleviating the structural delamination. PBCC-CeO2 electrodes exhibited a degradation rate of 0.095 mV h-1 at 650 °C during a nearly 500-h test as compared with 0.907 mV h-1 observed during the 135-h test for PBCC. Additionally, a remarkable increase in electrolysis current density from 636 to 934 mA cm-2 under 1.3 V and a maximum power density from 912 to 989 mW cm-2 upon incorporating CeO2 into PBCC is also observed. BSCF-CeO2 and LSM-CeO2 also show enhanced electrochemical performance and prolonged stability as compared to BSCF and LSM. This work offers a strategy to mitigate the structural delamination of conventional electrodes to boost the performance of rSOCs.

Enhanced polarization switching characteristics of HfO2 ultrathin films via acceptor-donor co-doping

In the realm of ferroelectric memories, HfO2-based ferroelectrics stand out because of their exceptional CMOS compatibility and scalability. Nevertheless, their switchable polarization and switching speed are not on par with those of perovskite ferroelectrics. It is widely acknowledged that defects play a crucial role in stabilizing the metastable polar phase of HfO2. Simultaneously, defects also pin the domain walls and impede the switching process, ultimately rendering the sluggish switching of HfO2. Herein, we present an effective strategy involving acceptor-donor co-doping to effectively tackle this dilemma. Remarkably enhanced ferroelectricity and the fastest switching process ever reported among HfO2 polar devices are observed in La3+-Ta5+ co-doped HfO2 ultrathin films. Moreover, robust macro-electrical characteristics of co-doped films persist even at a thickness as low as 3 nm, expanding potential applications of HfO2 in ultrathin devices. Our systematic investigations further demonstrate that synergistic effects of uniform microstructure and smaller switching barrier introduced by co-doping ensure the enhanced ferroelectricity and shortened switching time. The co-doping strategy offers an effective avenue to control the defect state and improve the ferroelectric properties of HfO2 films.

Enhanced Exchange Bias in Epitaxial High-Entropy Oxide Heterostructures

High-entropy oxides (HEOs) have gained significant interest in recent years due to their unique structural characteristics and potential to tailor functional properties. However, the electronic structure of the HEOs currently remains vastly unknown. In this work, combining magnetometry measurements, scanning transmission electron microscopy, and element-specific X-ray absorption spectroscopy, the electronic structure and magnetic properties of the perovskite-HEO La(Cr0.2Mn0.2Fe0.2Co0.2Ni0.2)O3 epitaxial thin films are systemically studied. It is found that enhanced magnetic frustration emerges from competing exchange interactions of the five transition-metal cations with energetically favorable half-filled/full-filled electron configurations, resulting in an unprecedented large vertical exchange bias effect in the single-crystalline films. Furthermore, our findings demonstrate that the La(Cr0.2Mn0.2Fe0.2Co0.2Ni0.2)O3 layer with a thickness down to 1 nm can be used as a pinning layer and strongly coupled with a ferromagnetic La0.7Sr0.3MnO3 layer, leading to a notable exchange bias and coercivity enhancement in a cooling field as small as 5 Oe. Our studies not only provide invaluable insight into the electronic structure of HEOs but also pave the way for a new era of large bias materials for spintronics devices.

Effects of the Unique Chromophore-Protein Interactions on the Primary Photoreaction of Schizorhodopsin

Schizorhodopsin (SzR) is a newly discovered microbial rhodopsin subfamily, functioning as an unusual inward-proton (H+) pump upon absorbing light. Two major protein structural differences around the chromophore have been found, resulting in unique chromophore-protein interactions that may be responsible for its unusual function. Therefore, it is important to elucidate how such a difference affects the primary photoreaction dynamics. We study the primary dynamics of SzR and its C75S mutant by femtosecond time-resolved absorption (TA) spectroscopy. The obtained TA data revealed that the photoisomerization in SzR proceeds more slowly and less efficiently than typical outward H+-pumping rhodopsins and that it further slows in the C75S mutant. We performed impulsive stimulated Raman measurements to clarify the effect of the cysteine residue on the retinal chromophore and found that interactions with Cys75 flatten the retinal chromophore of wild-type SzR. We discuss the effect of the unique chromophore-cysteine interaction on the retinal isomerization dynamics and structure of SzR.

Factors associated with outcomes of second-line treatment for EGFR-mutant non-small-cell lung cancer patients after progression on first- or second-generation EGFR-tyrosine kinase inhibitor treatment

Purpose

Epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) are standard first-line treatments for advanced EGFR-mutant non-small-cell lung cancer (NSCLC) patients. However, factors associated with outcomes after progression on first-line therapy are seldom investigated.

Materials and methods

From January 2016 to December 2020, we enrolled 242 EGFR-mutant stage IIIB-IV NSCLC patients who progressed on first- or second-generation EGFR-TKI treatments, and 206 of them receive second-line treatments after disease progression. The factors that predict the survival outcomes of different second-line treatments after disease progression were evaluated. Clinical and demographic characteristics, including metastatic sites, neutrophil-to-lymphocyte ratio (NLR) at first-line progression, and second-line treatment regimens, and whether re-biopsied after disease progression or not, were reviewed for outcome analysis.

Results

The univariate analysis showed that the PFS was shorted in male patients (p =0.049), patients with ECOG performance state ≥ 2 (p =0.014), former smokers (p =0.003), patients with brain metastasis (p =0.04), second-line chemotherapy or EGFR-TKIs other than osimertinib (p =0.002), and NLR ≥5.0 (p=0.024). In addition, second-line osimertinib was associated with longer OS compared to chemotherapy and other EGFR-TKI treatment (p =0.001). In the multivariate analysis, only second-line osimertinib was an independent predictor of PFS (p =0.023). Re-biopsy after first-line treatment was associated with a trend of better OS. Patients with NLR ≥5.0 at disease progression had shorter OS than patients with NLR <5.0 (p = 0.008).

Conclusion

The benefits of osimertinib necessitate that aggressive re-biopsy after progression on first- or second-generation EGFR-TKI treatment is merited for appropriate second-line treatments to provide better outcomes for these patients.

Photonic-Crafting of Non-Volatile and Rewritable Antiferromagnetic Spin Textures with Drastic Difference in Electrical Conductivity

Antiferromagnetic spintronics is an emerging field of non-volatile data storage and information processing. The zero net magnetization and zero stray fields of antiferromagnetic materials eliminate interference between neighbor units, leading to high-density memory integrations. However, this invisible magnetic character at the same time also poses a great challenge in controlling and detecting magnetic states in antiferromagnets. Here, two antiferromagnetic spin states close in energy in strained BiFeO₃ thin films at room temperature are discovered. It can be reversibly switched between these two non-volatile antiferromagnetic states by a moderate magnetic field and a non-contact optical approach. Importantly, the conductivity of the areas with each antiferromagnetic textures is drastically different. It is conclusively demonstrated the capability of optical writing and electrical reading of these newly discovered bistable antiferromagnetic states in the BiFeO₃ thin films.

Presence of Delocalized Ti 3d Electrons in Ultrathin Single-Crystal SrTiO3

Strontium titanate (STO), with a wide spectrum of emergent properties such as ferroelectricity and superconductivity, has received significant attention in the community of strongly correlated materials. In the strain-free STO film grown on the SrRuO₃ buffer layer, the existing polar nanoregions can facilitate room-temperature ferroelectricity when the STO film thickness approaches 10 nm. Here we show that around this thickness scale, the freestanding STO films without the influence of a substrate show the tetragonal structure at room temperature, contrasting with the cubic structure seen in bulk form. The spectroscopic measurements reveal the modified Ti-O orbital hybridization that causes the Ti ion to deviate from its nominal 4+ valency (3d⁰ configuration) with excess delocalized 3d electrons. Additionally, the Ti ion in TiO₆ octahedron exhibits an off-center displacement. The inherent symmetry lowering in ultrathin freestanding films offers an alternative way to achieve tunable electronic structures that are of paramount importance for future technological applications.

Real-world effectiveness of second-line Afatinib versus chemotherapy for the treatment of advanced lung squamous cell carcinoma in immunotherapy-naïve patients

Background

Limited treatment options exist for relapsed advanced lung squamous cell carcinoma (SCC), leading to poor outcomes compared with adenocarcinoma. This study aimed to investigate the efficacy of second-line afatinib versus chemotherapy in patients with advanced lung SCC who progressed after first-line chemotherapy.

Methods

In this retrospective, multisite cohort study, we recruited patients with initial locally advanced or metastatic lung SCC from four institutes in Taiwan between June 2014 and October 2020. The primary endpoint of this study was progression-free survival (PFS), and the secondary endpoints were the objective response rate (ORR), disease control rate (DCR), and overall survival (OS).

Results

The present study enrolled 108 patients: 19 received second-line afatinib, and 89 received second-line chemotherapy. The median ages were 71 and 67 years, respectively. PFS was significantly longer among patients who received afatinib than among those who received chemotherapy (median 4.7 months [95% confidence interval (CI), 0.1–7.5] vs. 2.6 months [95% CI, 0.9–6.7]; hazard ratio (HR) 0.53 [95% CI 0.32–0.88], p = 0.013). Compared with the chemotherapy group, OS was longer in the afatinib group but did not reach significance (median 16.0 months [95% CI, 6.1–22.0] vs. 12.3 months [6.2–33.9]; HR 0.65 [95% CI 0.38–1.11], p = 0.112).

Conclusions

Afatinib offered a longer PFS and comparable OS to chemotherapy in advanced lung SCC patients in a real-world setting, it may be considered as a 2nd line alternative treatment choice for immunotherapy unfit advanced lung SCC patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08920-3.

A Unified View on Varied Ultrafast Dynamics of the Primary Process in Microbial Rhodopsins

All-trans to 13-cis photoisomerization of the protonated retinal Schiff base (PRSB) chromophore is the primary step that triggers various biological functions of microbial rhodopsins. While this ultrafast primary process has been extensively studied, it has been recognized that the relevant excited-state relaxation dynamics differ significantly from one rhodopsin to another. To elucidate the origin of the complicated ultrafast dynamics of the primary process in microbial rhodopsins, we studied the excited-state dynamics of proteorhodopsin, its D97N mutant, and bacteriorhodopsin by femtosecond time-resolved absorption (TA) spectroscopy in a wide pH range. The TA data showed that their excited-state relaxation dynamics drastically change when pH approaches the pK_a of the counterion residue of the PRSB chromophore in the ground state. This result reveals that the varied excited-state relaxation dynamics in different rhodopsins mainly originate from the difference of the ground-state heterogeneity (i.e., protonation/deprotonation of the PRSB counterion).

Mechanically tunable exchange coupling of Co/CoO bilayers on flexible muscovite substrates

The employment of flexible muscovite substrates has given us the feasibility of applying strain to heterostructures dynamically by mechanical bending. In this study, this novel approach is utilized to investigate strain effects on the exchange coupling in ferromagnetic Co and anti-ferromagnetic CoO (Co/CoO) bilayers. Two different Co/CoO bilayer heterostructures were grown on muscovite substrates by oxide molecular beam epitaxy, with the CoO layer being purely (111)- and (100)-oriented. The strain-dependent exchange coupling effect can only be observed on Co/CoO(100)/mica but not on Co/CoO(111)/mica. The origin of this phenomenon is attributed to the anisotropic spin re-orientation induced by mechanical bending. The strain-dependent magnetic anisotropy of the bilayers determined by anisotropic magnetoresistance measurements confirms this conjecture. This study elucidates the fundamental understanding of how magnetic exchange coupling can be tuned by externally applied strain via mechanical bending and, hence, provides a novel approach for implementing flexible spintronic devices.

Acid-base equilibrium of the chromophore counterion results in distinct photoisomerization reactivity in the primary event of proteorhodopsin

Proteorhodopsin (PR) is a proton-pumping rhodopsin, and it is known to exhibit a multi-phasic decay of the excited-state population in the primary process. So far, this complex excited-state decay has been attributed to the branching of the relaxation pathway on the excited-state potential energy surface. However, a recent ultrafast spectroscopic study on a sodium-pumping rhodopsin suggested that such a complex decay may originate from the heterogeneity in the ground state due to the acid-base equilibrium of the counterion of the protonated retinal Schiff base (PRSB). In this study, we studied the excited-state dynamics of PR at pH 11 and 4, in which the counterion of the PRSB, Asp97, is completely deprotonated and protonated, respectively. The obtained time-resolved absorption data revealed that the excited-state lifetime is decisively governed by the protonation state of Asp97, and the photoisomerization of the PRSB chromophore proceeds faster and more efficiently when Asp97 is deprotonated. This conclusion was further supported by high similarity of the excited-state dynamics between PR at pH 4 and the D97N mutant in which Asp97 is replaced with neutral Asn. The results of this study suggest that the protonation state of the PRSB counterion plays a decisive role in determining the excited-state dynamics and the photoisomerization reactivity of rhodopsins in general, by making a significant influence on the exited-state potential energy surface of the PRSB chromophore.

Large magnetoresistance effects in Fe3O4

We investigated the magnetoresistance (MR) of a single crystal of magnetite, Fe₃O₄. In an effort to distinguish between different contributions to the MR the samples were prepared in two different initial magnetic states, i.e. by either zero-field or by field cooling from room temperature. The different magnetic structures in this sample have a dramatic effect on the magnetoresistance: for initially zero-field-cooled conditions a negative MR of about  -20% is observed just below the Verwey transition at [Formula: see text] K. For decreasing temperature the MR increases, changes sign at  ∼78 K and reaches a record positive value of  ∼45% at around 50 K. This behavior is completely absent in the field-cooled sample. Magnetization measurements corroborate an alignment of the easy magnetization direction in applied magnetic fields below [Formula: see text] as a cause of the strong effects observed in both, magnetization and MR. Our results point to a complex interplay of structural and magnetocrystalline effects taking place upon cooling Fe₃O₄ through [Formula: see text].

Deterministic optical control of room temperature multiferroicity in BiFeO3 thin films

Controlling ferroic orders (ferroelectricity, ferromagnetism and ferroelasticity) by optical methods is a significant challenge due to the large mismatch in energy scales between the order parameter coupling strengths and the incident photons. Here, we demonstrate an approach to manipulate multiple ferroic orders in an epitaxial mixed-phase BiFeO₃ thin film at ambient temperature via laser illumination. Phase-field simulations indicate that a light-driven flexoelectric effect allows the targeted formation of ordered domains. We also achieved precise sequential laser writing and erasure of different domain patterns, which demonstrates a deterministic optical control of multiferroicity at room temperature. As ferroic orders directly influence susceptibility and conductivity in complex materials, our results not only shed light on the optical control of multiple functionalities, but also suggest possible developments for optoelectronics and related applications.

Directly Probing Intermolecular Structural Change of a Core Fragment of β2-Microglobulin Amyloid Fibrils with Low-Frequency Raman Spectroscopy

Amyloid fibrils, which are ordered aggregates of proteins or peptides, have attracted keen interest because their deposition causes serious human diseases. Despite many studies utilizing X-ray crystallography, solid-state NMR, and other methods, intermolecular interactions governing the fibril formation remain largely unclear. Here, we used low-frequency Raman (LFR) spectroscopy to investigate the intermolecular β-sheet structure of a core fragment of β₂-microglobulin amyloid fibrils, β₂m_21-29, in aqueous buffer solutions. The LFR spectra (approximately 10-200 cm^-1) of β₂m_21-29 amyloid fibrils measured at different pH values (ranging from 6.8 to 8.0) revealed a broad-spectral pattern with a maximum at ∼80 cm^-1 below pH 7.2 and at ∼110 cm^-1 above pH 7.4. This observation is attributed to a pH-dependent structural change from an antiparallel to a parallel intermolecular β-sheet structure. Multivariate curve resolution-alternating least-squares (MCR-ALS) analysis enabled us to decompose the apparently monotonous LFR spectra into three distinctly different contributions: intermolecular vibrations of the parallel and antiparallel β-sheets and intramolecular vibrations of the peptide backbone. Peak positions of the obtained LFR bands not only exhibit a much more pronounced difference between the two β-sheets than the conventional amide I band, but they also suggest stronger intermolecular interaction, due presumably to the hydrophobic effect, in the parallel β-sheet than in the antiparallel β-sheet. The present results show that LFR spectroscopy in combination with the MCR-ALS analysis holds promise for real-time tracking of the intermolecular dynamics of amyloid fibril formation under physiological conditions.

Heteroepitaxy of Fe3O4/Muscovite: A New Perspective for Flexible Spintronics

Spintronics has captured a lot of attention since it was proposed. It has been triggering numerous research groups to make their efforts on pursuing spin-related electronic devices. Recently, flexible and wearable devices are in a high demand due to their outstanding potential in practical applications. In order to introduce spintronics into the realm of flexible devices, we demonstrate that it is feasible to grow epitaxial Fe₃O₄ film, a promising candidate for realizing spintronic devices based on tunneling magnetoresistance, on flexible muscovite. In this study, the heteroepitaxy of Fe₃O₄/muscovite is characterized by X-ray diffraction, high-resolution transmission electron microscopy, and Raman spectroscopy. The chemical composition and magnetic feature are investigated by a combination of X-ray photoelectron spectroscopy and X-ray magnetic circular dichroism. The electrical and magnetic properties are examined to show the preservation of the primitive properties of Fe₃O₄. Furthermore, various bending tests are performed to show the tunability of functionalities and to confirm that the heterostructures retain the physical properties under repeated cycles. These results illustrate that the Fe₃O₄/muscovite heterostructure can be a potential candidate for the applications in flexible spintronics.

[Effect of occupational lead exposure on the blood pressure of lead-exposed workers]

Objective: To investigate the effect of occupational lead exposure on blood pressure and pro-vide supportive evidence of health protection on lead - exposed workers. Methods: 612 workers (452 lead - ex-posed workers, 160 workers as control) were recruited in the battery factory. The blood lead concentration and blood pressure were detected by occupational health examination and biological monitoring. The relationship of blood lead concentration and blood pressure wasanalyzed. Results: The blood lead concentration in the exposed group (249.84±137.74) μg/L was higher than that of the control group (117.25±70.15) μg/L, and the differ-ence was statistically significant (P<0.01) . The difference of abnormal blood pressure and diastolic pressure among the exposed and the control group was statistically significant (P<0.05) . The abnormal blood pressure rate, systolic pressure rate and diastolic pressure rate in the 400~726 μg/L group was higher than that of the 6~199 μg/L and 200~399 μg/L group, and the difference was statistically significant (P<0.01) . Multiple lin-ear regression analysis showed that the influencing factors of the systolic pressure followed by sex, age, length of service and blood lead concentration, diastolic pressure followed by sex, age, smoke and blood lead concen-tration. Conclusion: These findings suggest that long - term occupational lead exposure may result in the in-crease of blood lead concentration.

A solid-state cation exchange reaction to form multiple metal oxide heterostructure nanowires

Metal oxide nanostructures have been investigated extensively due to their wide range of physical properties; zinc oxide is one of the most promising materials. It exhibits fascinating functional properties and various types of morphologies. In particular, ZnO heterostructures have attracted great attention because their performance can be modified and further improved by the addition of other materials. In this study, we successfully transformed ZnO nanowires (NWs) into multiple ZnO/Al₂O₃ heterostructure NWs via a solid-state cation exchange reaction. The experiment was carried out in situ via an ultrahigh vacuum transmission electron microscope (UHV-TEM), which was equipped with a video recorder. Moreover, we analyzed the structure and composition of the heterostructure NWs by Cs-corrected STEM equipped with EDS. Based on these experimental results, we inferred a cation exchange reaction ion path model. Additionally, we investigated the defects that appeared after the cation reaction, which resulted from the remaining zinc ions. These multiple heterostructure ZnO/Al₂O₃ NWs exhibited excellent UV sensing sensitivity and efficiency.

[SPINK3: A novel growth factor that promotes rat liver regeneration]

Serine peptidase inhibitor, Kazal type 3 (SPINK3) is a trypsin inhibitor, and also a growth factor that has an identical structure to epidermal growth factor (EGF), which could combine with epidermal growth factor receptor (EGFR) to promote cell proliferation. To shed light on the role and regulation mechanism of SPINK3 in rat liver regeneration (LR), Rat Genome 230 2.0 assay was used to detect the expression profiles of LR genes after partial hepatectomy (PH). The results showed that Spink3 was significantly up-regulated at 2-24 h and 72-168 h after PH. In the present study, RT-PCR and immunoblotting were used to validate the assay results. Ingenuity Pathway Analysis 9.0 (IPA) software was used to build the SPINK3 signaling regulating LR and analyze the possible mechanism. And then the expression of cell proliferation-associated gene Ccna2 was examined by RT-PCR in normal rat liver cell line BRL-3A in which Spink3 was overexpressed. The results showed that Ccna2 was significantly up-regulated in BRL-3A in which Spink3 was over-expressed. SPINK3 combining with EGFR accelerated cell proliferation during rat liver regeneration via P38, PKC, JAK-STAT and AKT pathways. Thus, SPINK3 was likely to promote hepatocytes proliferation in LR through P38, PKC, JAK-STAT and AKT.

Branches of the NF-κB signaling pathway regulate proliferation of oval cells in rat liver regeneration

The NF-kB (nuclear factor kB) pathway is involved in the proliferation of many cell types. To explore the mechanism of the NF-kB signaling pathway underlying the oval cell proliferation during rat liver regeneration, the Rat Genome 230 2.0 Array was used to detect expression changes of NF-kB signaling pathway-related genes in oval cells. The results revealed that the expression levels of many genes in the NF-kB pathway were significantly changed. This included 48 known genes and 16 homologous genes, as well as 370 genes and 85 homologous genes related to cell proliferation. To further understand the biological significance of these changes, an expression profile function was used to analyze the potential biological processes. The results showed that the NF-kB pathway promoted oval cell proliferation mainly through three signaling branches; the tumor necrosis factor alpha branch (TNF-a pathway), the growth factor branch, and the chemokine branch. An integrated statistics method was used to define the key genes in the NF-kB pathway. Seven genes were identified to play vital roles in the NF-kB pathway. To confirm these results, the protein content, including two key genes (TNF and FGF11) and two non-key genes (CCL2 and TNFRSF12A), were analyzed using two-dimensional gel electrophoresis and MALDI-TOF/TOF mass spectrometry. The results were generally consistent with those of the array data. To conclude, three branches and seven key genes were involved in the NF-kB signaling pathway that regulates oval cell proliferation during rat liver regeneration.

Branches of NF-κb signaling pathway regulate hepatocyte proliferation in rat liver regeneration

Previous studies have demonstrated that the nuclear factor κB (NF-κB) pathway is involved in promoting cell proliferation. To further explore the regulatory branches and their sequence in the NF-κB pathway in the promotion of hepatocyte proliferation at the transcriptional level during rat liver regeneration, Rat Genome 230 2.0 array was used to detect the expression changes of the isolated hepatocytes. We found that many genes involved in the NF-κB pathway (including 73 known genes and 19 homologous genes) and cell proliferation (including 484 genes and 104 homologous genes) were associated with liver regeneration. Expression profile function (Ep) was used to analyze the biological processes. It was revealed that the NF-κB pathway promoted hepatocyte proliferation through three branches. Several methods of integrated statistics were applied to extract and screen key genes in liver regeneration, and it indicated that eight genes may play a vital role in rat liver regeneration. To confirm the above predicted results, Ccnd1, Jun and Myc were analyzed using qRT-PCR, and the results were generally consistent with that of microarray data. It is concluded that 3 branches and 8 key genes involved in the NF-κB pathway regulate hepatocyte proliferation during rat liver regeneration.

Gene expression profiling analysis of 5-hydroxytryptamine signaling pathway in rat regenerating liver and different types of liver cells

We examined the gene expression profiles of the 5-hydroxytryptamine signaling pathway in the regenerating liver and 8 types of liver cells during rat liver regeneration, and explored expression differences in 5-hydroxytryptamine signaling pathway genes at the level of tissues and cells, as well as the role of the pathway on liver regeneration. Eight types of rat regenerating liver cells were isolated using Percoll density-gradient centrifugation and immunomagnetic bead methods. Rat Genome 230 2.0 Array was used to detect expression changes in 5-hydroxytryptamine signaling pathway genes. The results showed that 26, 47, 8, 21, 16, 19, 22, 27, and 20 genes changed significantly in hepatocytes, biliary epithelial cells, hepatic stellate cells, oval cells, sinusoidal endothelial cells, Kupffer cells, pit cells, dendritic cells, and the regenerating liver, respectively. Synthetic effects of 5-hydroxytryptamine signaling pathway genes in 8 types of liver cells showed that 26 genes were expressed significantly; the expression trends of 10 genes were the same in the regenerating liver, while others were different. Based on the gene expression profiles of the 8 types of liver cells, 5-hydroxytryptamine promoted hepatocyte proliferation through the RAS and STAT3 signaling pathways, proliferation and differentiation of sinusoidal endothelial cells through the STAT3 signaling pathway, and proliferation and apoptosis of pit cells through the AKT3 signaling pathway. There were large differences in genes involved in 5-hydroxytryptamine signaling at the tissue and cellular levels; thus, liver regeneration should be studied in-depth at the cellular level to reveal the molecular mechanism of liver regeneration.

Speed limit of the insulator-metal transition in magnetite

As the oldest known magnetic material, magnetite (Fe3O4) has fascinated mankind for millennia. As the first oxide in which a relationship between electrical conductivity and fluctuating/localized electronic order was shown, magnetite represents a model system for understanding correlated oxides in general. Nevertheless, the exact mechanism of the insulator-metal, or Verwey, transition has long remained inaccessible. Recently, three-Fe-site lattice distortions called trimerons were identified as the characteristic building blocks of the low-temperature insulating electronically ordered phase. Here we investigate the Verwey transition with pump-probe X-ray diffraction and optical reflectivity techniques, and show how trimerons become mobile across the insulator-metal transition. We find this to be a two-step process. After an initial 300 fs destruction of individual trimerons, phase separation occurs on a 1.5±0.2 ps timescale to yield residual insulating and metallic regions. This work establishes the speed limit for switching in future oxide electronics.

Symmetry of orbital order in Fe3O4 studied by Fe L(2,3) resonant x-ray diffraction

We studied the symmetry of the Fe 3d wave function in magnetite below the Verwey temperature T(V) with resonant soft-x-ray diffraction. Although the lattice structure of the low-temperature phase of Fe(3)O(4) is well described by the pseudo-orthorhombic Pmca with a slight monoclinic P2/c distortion, we find that the 3d wave function does not reflect the Pmca symmetry, and its distortion toward monoclinic symmetry is by far larger than that of the lattice. The result supports a scenario in which the Verwey transition involves the ordering of t(2g) orbitals with complex-number coefficients.

Resonant soft x-ray scattering from stepped surfaces of SrTiO3

We studied the resonant diffraction signal from stepped surfaces of SrTiO(3) at the Ti 2p → 3d (L(2,3)) resonance in comparison with x-ray absorption (XAS) and specular reflectivity data. The steps on the surface form an artificial superstructure suitable as a model system for resonant soft x-ray diffraction. A small step density on the surface is sufficient to produce a well defined diffraction peak. We determined the optical parameters of the sample across the resonance and found that the differences between the energy dependence of the x-ray absorption signal, the specular reflectivity and the step-related peak reflect the different quantities probed in these signals. When recorded at low incidence or detection angles, XAS and specular reflectivity spectra are strongly distorted by the changes of the angle of total reflection with energy. The resonant diffraction spectrum is less affected and can be used as a spectroscopic probe even in less favorable geometries.

Eight paths of ERK1/2 signalling pathway regulating hepatocyte proliferation in rat liver regeneration

Although it is known that hormones, growth factors and integrin promote hepatocyte proliferation in liver regeneration (LR) through ERK1/2 signalling pathway, reports about regulating processes of its intracellular paths in hepatocytes of LR are limited. This study aims at exploring which paths of ERK1/2 signalling pathway participate in the regulation of rat LR, especially in hepatocyte proliferation, and how they do so. In all, 14 paths and 165 genes are known to be involved in ERK1/2 signalling pathway. Of them, 161 genes are included in Rat Genome 230 2.0 Array. This array was used to detect expression changes of genes related to ERK1/2 signalling pathway in isolated hepatocytes of rat LR, showing that 60 genes were related to hepatocytes of LR. In addition, bioinformatics and systems biology methods were used to analyse the roles of 14 above paths in regenerating hepatocytes. We found that three paths, RTK→SHC→GRB2/SOS→RAS→RAF, IntegrinΒ→FAK→RAC→PAK→RAF and GΒγ→PI3KΒγ→RAC→PAK→RAF, promoted the G1 phase progression of hepatocytes by activating ERK1/2. A further four paths, Gq→PLCΒ→PKC→SRC/PYK2→GRB2/SOS→RAS→RAF, RTK→PLCγ→PKC→SRC/PYK2→GRB2/SOS→RAS→RAF, IntegrinΒ→FAK/SRC→GRB2/SOS→RAS→RAF and IntegrinΒ→FAK→RAC→PAK→RAF, advanced the cell progression of S phase and G(2)/M checkpoint by activating ERK1/2, and so did PP1/2→Mek1/2 by decreasing the negative influence on ERK1/2. At the late phase of LR, Gαs→AC→EPAC→Rap1→Raf blocked hepatocyte proliferation by decreasing the activity of ERK1/2 and so did PP1/2→Mek1/2. In summary, 60 genes and 8 paths of ERK1/2 signalling pathway regulated hepatocyte proliferation in rat LR.

Differential gene expression and functional analysis of pit cells from regenerating rat liver

Hepatic pit cells are a population of large granular lymphocytes that substantially contribute to hepatic immunity. Studies have proven that pit cells have a role in liver regeneration, but the details of the relationship between pit cells and liver regeneration is not clear at present. We subjected rats to a two-third hepatectomy; pit cells with high purity were obtained with Percoll density centrifugation and immunomagnetic bead methods, and the changes in mRNA levels in pit cells from the regenerating liver were monitored up to 168 h using a Rat Genome 230 2.0 Array composed of 25,020 distinct rat liver cDNA clones. Of the 25,020 genes analyzed, 612 known and 358 unknown genes were identified to be associated with liver regeneration. The 612 known genes are classified into up-regulation and down-regulation patterns based on the expression levels; they primarily participate in at least 23 biological activities based on gene ontology analysis. Together with gene function enrichment analysis, cytokines and a growth factor-mediated pathway in pit cells were activated at an early phase of liver regeneration; pit cell proliferation occurred from 24-72 h after liver hepatectomy; the machinery of pit cell differentiation commenced early and came into play late; an immune/inflammatory response was enhanced late. Expression pattern analysis of functionally classified genes in pit cells can give insights into the relationship between pit cells and liver regeneration.

Spin blockade, orbital occupation, and charge ordering in La1.5Sr0.5CoO4

Using Co-L2,3 and O-K x-ray absorption spectroscopy, we reveal that the charge ordering in La1.5Sr0.5CoO4 involves high spin (S=3/2) Co2+ and low spin (S=0) Co3+ ions. This provides evidence for the spin-blockade phenomenon as a source for the extremely insulating nature of the La2-xSrxCoO4 series. The associated e{g}{2} and e{g}{0} orbital occupation accounts for the large contrast in the Co-O bond lengths and, in turn, the high charge ordering temperature. Yet, the low magnetic ordering temperature is naturally explained by the presence of the nonmagnetic (S=0) Co3+ ions. From the identification of the bands we infer that La1.5Sr0.5CoO4 is a narrow band material.

Crystal-field level inversion in lightly Mn-doped Sr3Ru2O7

Sr3(Ru(1-x)Mnx)2O7, in which 4d-Ru is substituted by the more localized 3d-Mn, is studied by x-ray dichroism and spin-resolved density functional theory. We find that Mn impurities do not exhibit the same 4+ valence of Ru, but act as 3+ acceptors; the extra eg electron occupies the in-plane 3d(x2-y2) orbital instead of the expected out-of-plane 3d(3z2-r2). We propose that the 3d-4d interplay, via the ligand oxygen orbitals, is responsible for this crystal-field level inversion and the material's transition to an antiferromagnetic, possibly orbitally ordered, low-temperature state.

Determining the crystal-field ground state in rare earth heavy fermion materials using soft-x-ray absorption spectroscopy

We infer that soft-x-ray absorption spectroscopy is a versatile method for the determination of the crystal-field ground state symmetry of rare earth heavy fermion systems, complementing neutron scattering. Using realistic and universal parameters, we provide a theoretical mapping between the polarization dependence of Ce M(4,5) spectra and the charge distribution of the Ce 4f states. The experimental resolution can be orders of magnitude larger than the 4f crystal-field splitting itself. To demonstrate the experimental feasibility of the method, we investigated CePd2Si2, thereby settling an existing disagreement about its crystal-field ground state.

Direct observation of t2g orbital ordering in magnetite

Using soft-x-ray diffraction at the site-specific resonances in the Fe L2,3 edge, we find clear evidence for orbital and charge ordering in magnetite below the Verwey transition. The spectra show directly that the (001/2) diffraction peak (in cubic notation) is caused by t2g orbital ordering at octahedral Fe2+ sites and the (001) by a spatial modulation of the t2g occupation.

Expression profiles of the genes associated with metabolism and transport of amino acids and their derivatives in rat liver regeneration

Amino acids (AA) are components of protein and precursors of many important biological molecules. To address effects of the genes associated with metabolism and transport of AA and their derivatives during rat liver regeneration (LR), we firstly obtained the above genes by collecting databases data and retrieving related thesis, and then analyzed their expression profiles during LR using Rat Genome 230 2.0 array. The LR-associated genes were identified by comparing the gene expression difference between partial hepatectomy (PH) and sham-operation (SO) rat livers. It was approved that 134 genes associated with metabolism of AA and their derivatives and 26 genes involved in transport of them were LR-associated. The initially and totally expressing number of these genes occurring in initial phase of LR (0.5-4 h after PH), G0/G1 (4-6 h after PH), cell proliferation (6-66 h after PH), cell differentiation and structure-function reconstruction of liver tissue (72-168 h after PH) were respectively 76, 17, 79, 5 and 162, 89, 564, 195, illustrating that these LR-associated genes were initially expressed mainly in initial stage, and functioned in different phases. Frequencies of up-regulation and down-regulation of them being separately 564 and 357 demonstrated that genes up-regulated outnumbered those down-regulated. Categorization of their expression patterns into 22 types implied the diversity of cell physiological and biochemical activities. According to expression changes and patterns of the above-mentioned genes in LR, it was presumed that histidine biosynthesis in the metaphase and anaphase, valine metabolism in the anaphase, and metabolism of glutamate, glutamine, asparate, asparagine, methionine, alanine, leucine and aromatic amino acid almost were enhanced in the whole LR; as for amino acid derivatives, transport of neutral amino acids, urea, gamma-aminobutyric acid, betaine and taurine, metabolism of dopamine, heme, S-adenosylmethionine, thyroxine, and biosynthesis of hydroxyproline, nitric oxide, orinithine, polyamine, carnitine, selenocysteine were augmented during the entire liver restoration. Above results showed that metabolism and transport of AA and their derivates were necessary in liver regeneration.

Modelling respiratory infection control measure effects

One of the most pressing issues in facing emerging and re-emerging respiratory infections is how to bring them under control with current public health measures. Approaches such as the Wells-Riley equation, competing-risks model, and Von Foerster equation are used to prioritize control-measure efforts. Here we formulate how to integrate those three different types of functional relationship to construct easy-to-use and easy-to-interpret critical-control lines that help determine optimally the intervention strategies for containing airborne infections. We show that a combination of assigned effective public health interventions and enhanced engineering control measures would have a high probability for containing airborne infection. We suggest that integrated analysis to enhance modelling the impact of potential control measures against airborne infections presents an opportunity to assess risks and benefits. We demonstrate the approach with examples of optimal control measures to prioritize respiratory infections of severe acute respiratory syndrome (SARS), influenza, measles, and chickenpox.

Spectroscopy of stripe order in La1.8Sr0.2NiO4 using resonant soft x-ray diffraction

Strong resonant enhancements of the charge-order and spin-order superstructure-diffraction intensities in La1.8Sr0.2NiO4 are observed when x-ray energies in the vicinity of the Ni L2,3 absorption edges are used. The pronounced photon-energy and polarization dependences of these diffraction intensities allow for a critical determination of the local symmetry of the ordered spin and charge carriers. We found that not only the antiferromagnetic order but also the charge-order superstructure resides within the NiO2 layers; the holes are mainly located on in-plane oxygens surrounding a Ni2+ site with the spins coupled antiparallel in close analogy to Zhang-Rice singlets in the cuprates.

Mineralization of polyethylene glycol in aqueous solution by hydrogen peroxide with basic oxygen furnace slag

This study evaluated the dissolution behavior of basic oxygen furnace slag (BOF slag) and the performance of H2O2 with BOF slag denoted as H2O2/BOF slag process to degrade polyethylene glycol (PEG) in the aqueous solution. The concentration of total organic carbon (TOC) was chosen as a mineralization index of the degradation of PEG by the H2O2/BOF slag process. A first-order kinetic model with respect to TOC was adopted to represent the mineralization of PEG by H2O2/BOF slag process. The experimental results in this study suggested that dosages with 3.98 x 10(-4) mole min(-1) l(-1) H2O2 and 15 g l(-1) BOF slag loading in the solution at pH 2 provided the optimal operation conditions for the mineralization of PEG yielding a 75.5% treatment efficiency at 100 min reaction time. The H2O2/Fe2+ ratio was then determined to be 13.5:1.

Spin and orbital magnetic moments of Fe3O4

We present measurements of the spin and orbital magnetic moments of Fe3O4 by using SQUID and magnetic circular dichroism in soft x-ray absorption. The measurements show that Fe3O4 has a noninteger spin moment, in contrast to its predicted half-metallic feature. Fe3O4 also exhibits a large unquenched orbital moment. Calculations using the local density approximation including the Hubbard U method and the configuration interaction cluster-model suggest that strong correlations and spin-orbit interaction of the 3d electrons result in the noninteger spin and large orbital moments of Fe3O4.

Adsorption of acid dyes from aqueous solution on activated bleaching earth

In the present study, activated bleaching earth was used as clay adsorbent for an investigation of the adsorbability and adsorption kinetics of acid dyes (i.e., acid orange 51, acid blue 9, and acid orange 10) with three different molecular sizes from aqueous solution at 25 degrees C in a batch adsorber. The rate of adsorption has been investigated under the most important process parameters (i.e., initial dye concentration). A simple pseudo-second-order model has been tested to predict the adsorption rate constant, equilibrium adsorbate concentration, and equilibrium adsorption capacity by the fittings of the experimental data. The results showed that the adsorbability of the acid acids by activated bleaching earth follows the order: acid orange 51 > acid blue 9 > acid orange 10, parallel to the molecular weights and molecular sizes of the acid dyes. The adsorption removals (below 3%) of acid blue 9 and acid orange 10 onto the clay adsorbent are far lower than that (approximately 24%) of acid orange 51. Further, the adsorption kinetic of acid orange 51 can be well described by the pseudo-second-order reaction model. Based on the isotherm data obtained from the fittings of the adsorption kinetics, the Langmuir model appears to fit the adsorption better than the Freundlich model. The external coefficients of mass transfer of the acid orange 51 molecule across the boundary layer of adsorbent particle have also been estimated at the order of 10(-4)-10(-5) cm s(-1) based on the film-pore model and pseudo-second-order reaction model.

Decomposition of 2-mercaptothiazoline in aqueous solution by ozonation

This study investigates the ozonation of 2-mercaptothiazoline (2-MT). The 2-MT is one of the important organic additives for the electroplating solution of the printed wiring board industry and has been widely used as a corrosion inhibitor in many industrial processes. It is of concern for the aquatic pollution control especially in the wastewaters. Semibatch ozonation experiments in the completely stirred tank reactor are performed under various concentrations of input ozone. The concentrations of 2-MT, sulfate, and ammonium are analyzed at specified time intervals to elucidate the decomposition of 2-MT during the ozonation. In addition, the time variation of the dissolved ozone concentration (C(ALb)) is continuously monitored in the course of experiments. Total organic carbon (TOC) is chosen and measured as a mineralization index of the ozonation of 2-MT. The results indicate that the decomposition of 2-MT is efficient, while the mineralization of TOC is limited via the ozonation only. Simultaneously, the yield of sulfate with the maximum value of about 47% is characterized by the increases of TOC removal and ozone consumption. These results can provide some useful information for assessing the feasibility of the treatment of 2-MT in the aqueous solution by the ozonation.

Orbital ordering in La0.5Sr1.5MnO4 studied by soft X-ray linear dichroism

We found that the conventional model of orbital-ordering of 3x(2)-r(2)/3y(2)-r(2) type in the e(g) states of La0.5Sr1.5MnO4 is incompatible with measurements of linear dichroism in the Mn 2p-edge x-ray absorption, whereas these e(g) states exhibit predominantly cross-type orbital ordering of x(2)-z(2)/y(2)-z(2). LDA+U band-structure calculations reveal that such a cross-type orbital-ordering results from a combined effect of antiferromagnetic structure, Jahn-Teller distortion, and on-site Coulomb interactions.

HSV amplicon delivery of glial cell line-derived neurotrophic factor is neuroprotective against ischemic injury

Direct intracerebral administration of glial cell line-derived neurotrophic factor (GDNF) is neuroprotective against ischemia-induced cerebral injury. Utilizing viral vectors to deliver and express therapeutic genes presents an opportunity to produce GDNF within localized regions of an evolving infarct. We investigated whether a herpes simplex virus (HSV) amplicon-based vector encoding GDNF (HSVgdnf) would protect neurons against ischemic injury. In primary cortical cultures HSVgdnf reduced oxidant-induced injury compared to the control vector HSVlac. To test protective effects in vivo, HSVgdnf or HSVlac was injected into the cerebral cortex 4 days prior to, or 3 days, after a 60-min unilateral occlusion of the middle cerebral artery. Control stroke animals developed bradykinesia and motor asymmetry; pretreatment with HSVgdnf significantly reduced such motor deficits. Animals receiving HSVlac or HSVgdnf after the ischemic insult did not exhibit any behavioral improvement. Histological analyses performed 1 month after stroke revealed a reduction in ischemic tissue loss in rats pretreated with HSVgdnf. Similarly, these animals exhibited less immunostaining for glial fibrillary acidic protein and the apoptotic marker caspase-3. Taken together, our data indicate that HSVgdnf pretreatment provides protection against cerebral ischemia and supports the utilization of the HSV amplicon for therapeutic delivery of trophic factors to the CNS.

Differential expression of the cell line-derived neurotrophic factor (GDNF) receptor GFRalpha1 in heterozygous Gfralpha1 null-mutant mice after stroke

Exogenous administration of glial cell line-derived neurotrophic factor (GDNF) reduces ischemia-induced cerebral infarction. Cerebral ischemia induces gene expression of GDNF, GDNF-receptor alpha-1 (GFRalpha-1) and c-Ret, suggesting that a GDNF signaling cascade mechanism may be involved in endogenous neuroprotection during ischemia. In the present study, we examined if this endogenous neuroprotective pathway was altered in Gfralpha-1 deficient mice. Since mice homozygous for the Gfralpha-1 deletion (-/-) die within 24 h of birth, stroke-induced changes in the levels of Gfralpha-1 mRNA were studied in Gfralpha-1 heterozygous (+/-) mice and their wild-type (+/+) littermates. The right middle cerebral artery was transiently ligated for 45 min in anesthetized mice. Animals were killed at 0, 6, 12 and 24 h after the onset of reperfusion and levels of Gfralpha-1 mRNA were measured by in situ hybridization histochemistry. Previously, we showed that Gfralpha-1 (+/-) mice are more vulnerable to focal cerebral ischemia. In the present study, we found that basal levels of GFRalpha-1 mRNA were at similar low levels in cortex and striatum in adult Gfralpha-1 (+/+) and Gfralpha-1 (+/-) mice and that ischemia/reperfusion induced up-regulation of Gfralpha-1 mRNA in the lesioned and contralateral sides of cortex and striatum in both Gfralpha-1 (+/+) and GFRalpha-1 (+/-) mice. However, the ischemia/reperfusion induction of Gfralpha-1 mRNA was significantly higher in the cortex of wild type mice, as compared to Gfralpha-1 (+/-) mice. Moreover, the increased expression of Gfralpha-1 in striatum after reperfusion occurred earlier in the GFRalpha-1 (+/+) than in the Gfralpha-1 (+/-) mice. These results indicate that after ischemia, there is a differential up-regulation of Gfralpha-1 expression in Gfralpha-1 (+/+) and Gfralpha-1 (+/-) mice. Since GDNF has neuroprotective effects, the reduced up-regulation of Gfralpha-1 in Gfralpha-1 (+/-) mice at early time points after ischemia suggests that the responsiveness to GDNF and GDNF receptor mediated neuroprotection is attenuated in these genetically modified animals and may underlie their greater vulnerability.

Adsorption of polyethylene glycol (PEG) from aqueous solution onto hydrophobic zeolite

In the present study, a hydrophobic zeolite was used as an adsorbent for the adsorption of polyethylene glycol (PEG) in water solution and electroplating solution at 25 degrees C. The adsorption capacities were determined through the adsorption isotherms in a thermostated shaker. The rate of adsorption, on the other hand, was investigated in a batch adsorber under controlled process parameters such as initial PEG concentration (30, 70, 110, 150, 200, and 300 mg x dm(-3)), agitation speed (200, 800, and 1000 rpm), and adsorbent particle size (0.72, 1.44, and 2.03 mm). A batch kinetic model, according to a pseudo-second-order mechanism, has been tested to predict the rate constant of adsorption, equilibrium adsorption capacity, time of half-adsorption, and equilibrium concentration by the fitting of the experimental data. The results of the adsorption isotherm and kinetic studies show that the adsorption process can well be described with the Langmuir and Freundlich models and the pseudo-second-order equation, respectively. Comparing the values of adsorption parameters of PEG in water solution and electroplating solution, there are no significant differences. In addition, the effective diffusion coefficient of the PEG molecule in the microporous adsorbent has been estimated at about 3.20 x 10(-8) cm(2)s(-1) based on the restrictive diffusion model.

Bone morphogenetic proteins are involved in fetal kidney tissue transplantation-induced neuroprotection in stroke rats

Both bone morphogenetic proteins (BMPs) and glial cell line-derived neurotrophic factor (GDNF) reduce ischemia-induced cerebral injury in rats. Intracerebral transplantation of fetal kidney tissue, which normally expresses BMPs and GDNF during development, reduces ischemic injury in cerebral cortex. In this study, we tested the hypothesis that BMP is involved in this neuroprotective response. Fetal kidney tissue was cut into small pieces and transplanted into cortical areas adjacent to the right middle cerebral artery (MCA) in adult rats. In situ hybridization of brain indicated that these fetal kidney transplants contained high levels of BMP-7 mRNA three days after grafting. Immunohistochemical analysis of grafted brain showed co-localization of BMP-7 and PAX-2 immunoreactivity in the graft, suggesting that these transplants contained BMP protein. Some animals were grafted with fetal kidney tissue after intraventricular administration (ICV) of the BMP antagonist noggin (1 micro g) or after vehicle, followed by MCA ligation for 60 min. Animals receiving fetal kidney tissue transplantation developed significantly less body asymmetry, as compared to stroke animals that either did not receive transplantation or received fetal kidney grafts and noggin pretreatment. Analysis of these brains after triphenyltetrazolium chloride staining showed that fetal kidney tissue transplantation reduced the volume of infarction in the cerebral cortex. Noggin pretreatment reduced the protection induced by fetal kidney grafting, although noggin itself did not cause increase in cerebral infarction. Eight hours after ischemia, brain homogenates were obtained from grafted and control animals to assay caspase-3 enzymatic activity. This analysis demonstrated that fetal kidney grafts significantly reduced ischemia-induced caspase-3 activity. Reduction of caspase-3 activity could also be antagonized by noggin pretreatment. In conclusion, our data suggest that fetal kidney transplantation reduces ischemia/reperfusion-induced cortical infarction and behavioral deficits in adult rats, which are, at least partially, mediated through the effect of BMPs from the transplants.

Protective effects of glial cell line-derived neurotrophic factor in ischemic brain injury

Glial cell line-derived neurotrophic factor (GDNF), a member of the transforming growth factor-beta (TGF-beta) superfamily, has been shown to have trophic activity on dopaminergic neurons. Recent studies indicate that GDNF can protect the cerebral hemispheres from damage induced by middle cerebral arterial ligation. We found that such neuroprotective effects are mediated through specific GDNF receptor alpha-1 (GFRalpha1). Animals with a deficiency in GFRalpha-1 have less GDNF-induced neuroprotection. Ischemia also enhances nitric oxide synthase (NOS) activity, which can be attenuated by GDNF. These.data suggest that GDNF can protect against ischemic injury through a GFRalpha-1/NOS mechanism. We also found that the receptor for GDNF, GFRalpha1, and its signaling moiety c-Ret were upregulated, starting immediately after ischemia. This upregulation suggests that activation of an endogenous neuroprotective mechanism occurs so that responsiveness of GDNF can be enhanced at very early stages during ischemia.

Sex change in the protandrous black porgy, Acanthopagrus schlegeli: a review in gonadal development, estradiol, estrogen receptor, aromatase activity and gonadotropin

Black porgy, Acanthopagrus schlegeli Bleeker, a marine protandrous hermaphrodite, is functional male for the first two years of life but begins to sexually change to female after the third year. Testicular tissue and ovarian tissue was separated by connective tissue in the bisexual gonad. This sex pattern provides a very good model to study the endocrine mechanism of sex change in fish. The annual profiles of plasma estradiol, vitellogenin and 11-ketotestosterone concentrations in males were significantly different from those in the three-year-old females. Significantly high levels of plasma estradiol during the prespawning/spawning season and low levels of plasma 11-ketotestosterone during the spawning season were observed in the inversing females. No difference of plasma testosterone levels was observed in males and females. Oral administration of estradiol stimulated high levels of gonadal aromatase activity, plasma gonadotropin II levels and sex change in the two-year-old fish. Exogenous estradiol administered for 5-6 months induced a reversible sex change in one- and two-year-old fish. The sensitive period for estradiol treatment of sex change is from early prespawning to spawning season. Implantation with testosterone for more than a year could not block the natural sex change in three-year-old fish. Exogenous aromatase inhibitors (1,4,6-androstatriene-3,17-dione or fadrozole) suppressed aromatase activity in the brain. Oral administration with aromatase inhibitors for a year further inhibited the natural sex change in three-year-old black porgy and all fish became functional male with spermiation. Estrogen receptor alpha gene in the ovarian tissue of bisexual gonad is significantly less expressed than that in the vitellogenic ovary of female on the basis of reverse-transcription polymerase-chain reaction. There was no difference in the annual profiles of the plasma gonadotropin II levels in the males and natural inversing females. Plasma gonadotropin II levels were significantly higher in estradiol-treated group than those in the control. It is concluded that estradiol, aromatase activity and estrogen receptor in the ovarian tissue play an important role in the natural and controlled sex change in black porgy. The association of gonadotropin and sex change in black porgy is not clear.