Performance Improvement of a ZnGa2O4 Extended-Gate Field-Effect Transistor pH Sensor.

ZnGa2O4 sensing films were prepared using an RF magnetron sputtering system and connected to a commercial metal oxide semiconductor field-effect transistor (MOSFET) as the extended-gate field-effect transistor (EGFET) to detect pH values. Experimental parameters were adjusted by varying the oxygen flow rate in the process chamber to produce ZnGa2O4 sensing films with different oxygen ratios. These films were then treated in a furnace tube at an annealing temperature of 700 °C. The sensitivity and linearity of the constant current mode and the constant voltage mode were measured and analyzed in the pH range of 2-12. Under the deposition conditions with an oxygen ratio of 6%, the sensitivity reached 23.14 mV/pH and 33.49 µA/pH, with corresponding linearity values of 92.1 and 96.15%, respectively. Finally, the sensing performance of the ZnGa2O4 EGFET pH sensor with and without annealing processes was analyzed and compared.

Synthesis and biological evaluation of paeoveitol D derivatives as new melatonin receptor agonists with antidepressant activities.

Our previous study demonstrated that paeoveitol D, a benzofuran compound isolated from Paeonia veitchii, displayed activity on MT1 and MT2 receptors with agonistic ratios of 57.5% and 51.6% at a concentration of 1 mM. To explore the structure-activity relationships, 34 paeoveitol D derivatives were synthesized and evaluated for their MT1 and MT2 agonistic activities using the Fluo-8 calcium assay. Among them, 16 and 18 derivatives increased agonistic activities on the MT1 and MT2 receptors, respectively. Compound 18 indicated EC50 values of 21.0 and 298.9 µM on MT1 and MT2 receptors in agonistic dose response curves with Tango assays and shortened immobility time in the forced swim test. The preliminary mechanism-of-action investigation manifested that the antidepressant activity of compound 18 may be mediated by promoting serotonin (5-HT) and dopamine (DA) levels in the mice brain. Compound 18 also showed favorable pharmacokinetic profiles and low toxicity in vivo. These results suggest that compound 18 could be a potential antidepressant agent.

Atom-Dependent Edge-Enhanced Second-Harmonic Generation on MoS2 Monolayers.

Edge morphology and lattice orientation of single-crystal molybdenum disulfide (MoS2) monolayers, a transition metal dichalcogenide (TMD), possessing a triangular shape with different edges grown by chemical vapor deposition are characterized by atomic force microscopy and transmission electron microscopy. Multiphoton laser scanning microscopy is utilized to study one-dimensional atomic edges of MoS2 monolayers with localized midgap electronic states, which result in greatly enhanced optical second-harmonic generation (SHG). Microscopic S-zigzag edge and S-Mo Klein edge (bare Mo atoms protruding from a S-zigzag edge) terminations and the edge-atom dependent resonance energies can therefore be deduced based on SHG images. Theoretical calculations based on density functional theory clearly explain the lower energy of the S-zigzag edge states compared to the corresponding S-Mo Klein edge states. Characterization of the atomic-scale variation of edge-enhanced SHG is a step forward in this full-optical and high-yield technique of atomic-layer TMDs.

Galphas-biased beta2-adrenergic receptor signaling from restoring synchronous contraction in the failing heart.

Cardiac resynchronization therapy (CRT), in which both ventricles are paced to recoordinate contraction in hearts that are dyssynchronous from conduction delay, is the only heart failure (HF) therapy to date to clinically improve acute and chronic function while also lowering mortality. CRT acutely enhances chamber mechanical efficiency but chronically alters myocyte signaling, including improving ß-adrenergic receptor reserve. We speculated that the latter would identify unique CRT effects that might themselves be effective for HF more generally. HF was induced in dogs by 6 weeks of atrial rapid pacing with (HFdys, left bundle ablated) or without (HFsyn) dyssynchrony. We used dyssynchronous followed by resynchronized tachypacing (each 3 weeks) for CRT. Both HFdys and HFsyn myocytes had similarly depressed rest and ß-adrenergic receptor sarcomere and calcium responses, particularly the ß2-adrenergic response, whereas cells subjected to CRT behaved similarly to those from healthy controls. CRT myocytes exhibited suppressed Gαi signaling linked to increased regulator of G protein (heterotrimeric guanine nucleotide-binding protein) signaling (RGS2, RGS3), yielding Gαs-biased ß2-adrenergic responses. This included increased adenosine cyclic AMP responsiveness and activation of sarcoplasmic reticulum-localized protein kinase A. Human CRT responders also showed up-regulated myocardial RGS2 and RGS3. Inhibition of Gαi (with pertussis toxin, RGS3, or RGS2 transfection), stimulation with a Gαs-biased ß2 agonist (fenoterol), or transient (2-week) exposure to dyssynchrony restored ß-adrenergic receptor responses in HFsyn to the values obtained after CRT. These results identify a key pathway that is triggered by restoring contractile synchrony and that may represent a new therapeutic approach for a broad population of HF patients.

Betagamma-CAT, a non-lens betagamma-crystallin and trefoil factor complex from amphibian skin secretions, caused endothelium-dependent myocardial depression in isolated rabbit hearts.

Previous in vivo study demonstrated that betagamma-CAT, a newly identified non-lens betagamma-crystallin and trefoil factor complex from frog Bombina maxima skin secretions, possessed potent lethal toxicity on mammals resulted from hypotension and cardiorespiratory arrest. However, the mechanism of cardiac dysfunction induced by the protein is unknown. Here, we report that betagamma-CAT, with dosages of 0.8-3.0 nM, elicited an acute negative inotropic effect in isolated rabbit heart Langendorff preparations, which mimicked acute heart failure. In addition, the effect of betagamma-CAT on the hearts was mediated by endothelium-dependent coronary vasoconstriction (P<0.01, compared between endothelium-intact and removal hearts). After betagamma-CAT (3.0 nM) treatment, the positive signal of tumor necrosis factor-alpha (TNF-alpha) was detected mainly around the endothelial cell layer as detected by in situ indirect immunofluorescence, indicating that the release of TNF-alpha occurred. At the same time, a rapid TNF-alpha release was detected in primary cultured rabbit endocardial endothelial cells (REECs) treated with betagamma-CAT. After addition of betagamma-CAT (3.0 nM) for 10 min and 30 min, the TNF-alpha levels were increased to 57.33+/-3.22 pg/ml and 60.00+/-5.35 pg/ml (P<0.05, compared with the control values of 21.67+/-3.45 pg/ml and 33.70+/-6.24 pg/ml, respectively). At high concentrations, betagamma-CAT interfered with the cell viability of REECs (CC(50) about 25 nM). Taken together, betagamma-CAT was able to induce acute myocardial depression and the toxic effect might be partially explained by the release of TNF-alpha. The finding provides new information to understand the patho-physiological roles of non-lens betagamma-crystallins and trefoil factors.

Acute toxicity of betagamma-CAT, a naturally existing non-lens betagamma-crystallin and trefoil factor complex from frog Bombina maxima skin secretions.

In vertebrates, non-lens betagamma-crystallins are widely expressed in various tissues, but their functions are unknown. The molecular mechanisms of trefoil factors, initiators of mucosal healing and being greatly involved in tumorigenesis, have remained elusive. betagamma-CAT is the first example of a naturally existing multifunctional protein complex of a non-lens betagamma-crystallin and a trefoil factor from frog Bombina maxima skin secretions. Here we report the investigation of its in vivo toxic effects on mice and rabbits. The LD(50) values of betagamma-CAT on mice were determined to be 0.4 mg/kg and 20 microg/kg under intraperitoneal (i.p.) and intravenous (i.v.) injection, respectively. The mice subcutaneously injected with betagamma-CAT (6 microg/g body weight) showed strong hyperaemia of subcutaneous capillary vessel, but no hemorrhagic spots were observed. Intravenous injection of betagamma-CAT in rabbits (8-22 microg/kg body weight) caused a rapidly hypotensive effect and followed with cardiovascular collapse. Injection with betagamma-CAT (22 microg/kg, i.v.) significantly decreased hematocrit (P<0.05) and mean corpuscular volume (P<0.05) of the rabbits in 5 min. At the same time, the counts of platelets and white blood cells were significantly decreased (P<0.05), while the blood levels of glucose, lactate dehydrogenase and serum glutamic-oxaloacetic transaminase were significantly increased (P<0.05). Furthermore, serials of tissues edema and damages were also observed. These results indicate that betagamma-CAT rapidly caused several in vivo toxic effects on mammals and its lethal toxic potency was mainly contributed by hypotension and cardiovascular collapse, providing new clues for the understanding of the patho-physiological roles of non-lens betagamma-crystallins and trefoil factors.

Melanoma cell growth inhibition by betagamma-CAT, which is a novel non-lens betagamma-crystallin and trefoil factor complex from frog Bombina maxima skin.

In vertebrates, non-lens betagamma-crystallins are widely expressed in various tissues but their functions are unknown. The molecular mechanisms of trefoil factors, initiators of mucosal healing and being greatly involved in tumorigenesis, have remained elusive. betagamma-CAT, which is responsible for the potent hemolytic activity and lethal toxicity on mice of frog Bombina maxima skin secretions, is the first example of a non-lens betagamma-crystallin and trefoil factor complex. Its alpha- and beta-subunits show significant sequence homology to human Absent In Melanoma 1 and trefoil factors, respectively. Here, we showed that betagamma-CAT triggered two types of cellular responses in human melanoma cells. On one hand, the protein (25-200 pM) was able to stimulate cell migration in melanoma A375 cells. On the other hand, it inhibited cell proliferation by delaying S-G2/M cell phase transition. Blockade of the cell cycle was associated with increased p21/WAF1 expression, and reduced amounts of Cdc2 and Cdc25C. betagamma-CAT also reduced Cdc2 function by increasing the level of inactivated phospho-Cdc2. In addition, the expression of JunB, a well-known cell proliferation inhibitor, was significantly up-regulated. These results provide the first evidence of an anti-proliferative role for a non-lens betagamma-crystallin member and action mechanism via association with a trefoil factor.

Isolation, expression and characterization of a novel dual serine protease inhibitor, OH-TCI, from king cobra venom.

Snake venom Kunitz/BPTI members are good tools for understanding of structure-functional relationship between serine proteases and their inhibitors. A novel dual Kunitz/BPTI serine proteinase inhibitor named OH-TCI (trypsin- and chymotrypsin-dual inhibitor from Ophiophagus hannah) was isolated from king cobra venom by three chromatographic steps of gel filtration, trypsin affinity and reverse phase HPLC. OH-TCI is composed of 58 amino acid residues with a molecular mass of 6339Da. Successful expression of OH-TCI was performed as the maltose-binding fusion protein in E. coli DH5alpha. Much different from Oh11-1, the purified native and recombinant OH-TCI both had strong inhibitory activities against trypsin and chymotrypsin although the sequence identity (74.1%) between them is very high. The inhibitor constants (K(i)) of recombinant OH-TCI were 3.91 x 10(-7) and 8.46 x10(-8)M for trypsin and chymotrypsin, respectively. To our knowledge, it was the first report of Kunitz/BPTI serine proteinase inhibitor from snake venom that had equivalent trypsin and chymotrypsin inhibitory activities.

A novel non-lens betagamma-crystallin and trefoil factor complex from amphibian skin and its functional implications.

BACKGROUND: In vertebrates, non-lens betagamma-crystallins are widely expressed in various tissues, but their functions are unknown. The molecular mechanisms of trefoil factors, initiators of mucosal healing and being greatly involved in tumorigenesis, have remained elusive. PRINCIPAL FINDINGS: A naturally existing 72-kDa complex of non-lens betagamma-crystallin (alpha-subunit) and trefoil factor (beta-subunit), named betagamma-CAT, was identified from frog Bombina maxima skin secretions. Its alpha-subunit and beta-subunit (containing three trefoil factor domains), with a non-covalently linked form of alphabeta(2), show significant sequence homology to ep37 proteins, a group of non-lens betagamma-crystallins identified in newt Cynops pyrrhogaster and mammalian trefoil factors, respectively. betagamma-CAT showed potent hemolytic activity on mammalian erythrocytes. The specific antiserum against each subunit was able to neutralize its hemolytic activity, indicating that the two subunits are functionally associated. betagamma-CAT formed membrane pores with a functional diameter about 2.0 nm, leading to K(+) efflux and colloid-osmotic hemolysis. High molecular weight SDS-stable oligomers (>240-kDa) were detected by antibodies against the alpha-subunit with Western blotting. Furthermore, betagamma-CAT showed multiple cellular effects on human umbilical vein endothelial cells. Low dosages of betagamma-CAT (25-50 pM) were able to stimulate cell migration and wound healing. At high concentrations, it induced cell detachment (EC(50) 10 nM) and apoptosis. betagamma-CAT was rapidly endocytosed via intracellular vacuole formation. Under confocal microscope, some of the vacuoles were translocated to nucleus and partially fused with nuclear membrane. Bafilomycin A1 (a specific inhibitor of the vacuolar-type ATPase) and nocodazole (an agent of microtuble depolymerizing), while inhibited betagamma-CAT induced vacuole formation, significantly inhibited betagamma-CAT induced cell detachment, suggesting that betagamma-CAT endocytosis is important for its activities. CONCLUSIONS/SIGNIFICANCE: These findings illustrate novel cellular functions of non-lens betagamma-cyrstallins and action mechanism via association with trefoil factors, serving as clues for investigating the possible occurrence of similar molecules and action mechanisms in mammals.

Cloning of novel bombesin precursor cDNAs from skin of Bombina maxima.

Amphibian skin is a rich resource of bioactive peptides like proline-rich bombesin from frog Bombina maxima. A novel cDNA clone encoding a precursor protein that comprises proline-rich bombesin and a novel peptide, designated as bombestatin, was isolated from a skin cDNA library of B. maxima. The predicted primary structure of the novel peptide is WEVLLNVALIRLELLSCRSSKDQDQKESCGMHSW, in which two cysteines form a disulfide bond. A BLAST search of databases did not detect sequences with significant similarity. Bombestatin possesses dose-dependent contractile activity on rat stomach strips. The differences between cDNAs encoding PR-bombesin plus bombestatin and PR-bombesin alone are due to fragment insertions located in 3'-coding region and 3'-untranslational region, respectively.

Identification and molecular cloning of a novel neuromedin U analog from the skin secretions of toad Bombina maxima.

Amphibian skin contains rich neuropeptides. In the present study, a novel neuromedin U (NmU) analog was isolated from skin secretions of Chinese red belly toad Bombina maxima. Being 17-amino acids long, its primary structure was established as DSSGIVGRPFFLFRPRN-NH2, in which the C-terminal 8-residue segment (FFLFRPRN) is the same as that of rat NmU, while the N-terminal part DSSGIVGRP shows a great sequence variation compared with those of NmU peptides from different resources. The peptide, named Bm-NmU-17, was found to elicit concentration-dependent contractile effects on smooth muscle of rat uterus horns. The cDNA structure of the peptide, as obtained by a 3'-RACE strategy and subsequently cloning from a skin cDNA library, was found to contain a coding region of 438 nucleotides. The encoded precursor is composed of 145 amino acids with a single copy of Bm-NmU-17 located towards the C-terminus. The sequence of the peptide is preceded by a dibasic site (Lys-Arg) and followed by the sequence of Gly-Arg-Lys, providing the sites of cleavage and releasing of the mature peptide.

Cloning of bradykinin precursor cDNAs from skin of Bombina maxima reveals novel bombinakinin M antagonists and a bradykinin potential peptide.

Bombinakinin M (DLPKINRKGP-bradykinin) is a bradykinin-related peptide purified from skin secretions of the frog Bombina maxima. As previously reported, its biosynthesis is characterized by a tandem repeats with various copy numbers of the peptide and sometimes co-expressed with other structure-function distinguishable peptides. At present study, two novel cDNAs encoding bombinakinin M and its variants were cloned from a cDNA library from the skin of the frog. The encoded two precursor proteins are common in that each contains three repeats of a novel 16-amino acid peptide unit and one copy of kinestatin at their N- and C-terminal parts, respectively. They differ in that the first precursor contains two copies of bombinakinin M and the second one contains one copy of a novel bombinakinin M variant. Bombinakinin M was found to elicit concentration-dependent contractile effects on guinea pig ileum, with an EC50 value of 4 nM that is four times higher than that of bradykinin (1 nM). Interestingly, the synthetic peptide (DYTIRTRLH-amide), as deduced from the 16-amino acid peptide repeats in the newly cloned cDNAs, possessed weak inhibitory activity on the contractile effects of bombinakinin M, but not on that of bradykinin. Furthermore, the newly identified bombinakinin M variant (DLSKMSFLHG-Ile1-bradykinin), did not show contractile activity on guinea pig ileum, but showed potentiation effect on the myotropic activity of bradykinin. In a molar ratio of 1:58, it augmented the activity of bradykinin up to two-fold.