bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ghrelin Amplifies Dopamine Signaling by Cross Talk Involving Formation of Growth Hormone Secretagogue Receptor/Dopamine Receptor Subtype 1 Heterodimers
Authors: Jiang Hong , Betancourt Lorena , Smith Roy G. 
Published: April 2006

Abstract
Our objective is to determine the neuromodulatory role of ghrelin in the brain. To identify neurons that express the ghrelin receptor [GH secretagogue receptor (GHS-R)], we generated GHS-R-IRES-tauGFP mice by gene targeting. Neurons expressing the GHS-R exhibit green fluorescence and are clearly evident in the hypothalamus, hippocampus, cortex, and midbrain. Using immunohistochemistry in combination with green fluorescent protein fluorescence, we identified neurons that coexpress the dopamine receptor subtype 1 (D1R) and GHS-R. The potential physiological relevance of coexpression of these two receptors and the direct effect of ghrelin on dopamine signaling was investigated in vitro. Activation of GHS-R by ghrelin amplifies dopamine/D1R-induced cAMP accumulation. Intriguingly, amplification involves a switch in G protein coupling of the GHS-R from Gα11/q to Gαi/o by a mechanism consistent with agonist-dependent formation of GHS-R/D1R heterodimers. Most importantly, these results indicate that ghrelin has the potential to amplify dopamine signaling selectively in neurons that coexpress D1R and GHS-R.
Thyroid-Specific Enhancer-Binding Protein/NKX2.1 Is Required for the Maintenance of Ordered Architecture and Function of the Differentiated Thyroid
Authors: Kusakabe Takashi , Kawaguchi Akio , Hoshi Nobuo , Kawaguchi Rumi , Hoshi Sayuri , Kimura Shioko 
Published: April 2006

AbstractThyroid-specific enhancer-binding protein (T/ebp)/Nkx2.1-null mouse thyroids degenerate by embryonic day (E) 12–13 through apoptosis whereas T/ebp/Nkx2.1-heterogyzgous mice exhibit hypothyroidism with elevated TSH levels. To understand the role of T/ebp/Nkx2.1 in the adult thyroid, a thyroid follicular cell-specific conditional knockout (KO) mouse line, T/ebp(fl/fl);TPO-Cre, was established that expresses Cre recombinase under the human thyroid peroxidase (TPO) gene promoter. These mice appeared to be healthy and exhibited loss of T/ebp/Nkx2.1 expression in many, but not all, thyroid follicular cells as determined by immunohistochemistry and real-time PCR, thus presenting a T/ebp-thyroid-conditional hypomorphic mice. Detailed analysis of the thyroids from T/ebp(fl/fl), T/ebp(fl/fl);TPO-Cre, and T/ebp(fl/ko) mice, where the latter mouse line is derived from crosses with the original T/ebp/Nkx2.1-heterozygous mice, revealed that T/ebp(fl/fl);TPO-Cre mice can be classified into two groups with different phenotypes: one having atrophic/degenerative thyroid follicles with frequent presence of adenomas and extremely high serum TSH levels, and the other having an altered thyroid structure with reduced numbers of extraordinary dilated follicles consisting of excessive numbers of follicular cells as compared with those usually found in the normal thyroid. The latter phenotype was also observed in aged T/ebp(fl/ko) mouse thyroids. In vitro three-dimensional thyroid primary cultures using thyroids from T/ebp(fl/fl);TPO-Cre, T/ebp(fl/ko), and T/ebp(fl/fl) mice, and the latter treated with recombinant adenovirus with and without Cre expression, demonstrated that only cells from T/ebp(fl/fl) mice without adeno-Cre treatment formed follicular structures. Taken together, these results suggest that T/ebp/Nkx2.1 is required for maintenance of the normal architecture and function of differentiated thyroids.
Single-Chain, Triple-Domain Gonadotropin Analogs with Disulfide Bond Mutations in the α-Subunit Elicit Dual Follitropin and Lutropin Activities in Vivo
Authors: Jablonka-Shariff Albina , Kumar T. Rajendra , Eklund Joshua , Comstock Anna , Boime Irving 
Published: April 2006

AbstractThe human glycoprotein hormones chorionic gonadotropin (CG), TSH, LH, and FSH are heterodimers composed of a common α-subunit and a hormone-specific β-subunit. The subunits assemble noncovalently early in the secretory pathway. LH and FSH are synthesized in the same cell (pituitary gonadotrophs), and several of the α-subunit sequences required for association with either β-subunit are different. Nevertheless, no ternary complexes are observed for LH and FSH in vivo, i.e. both β-subunits assembled with a single α-subunit. To address whether the α-subunit can interact with more than one β-subunit simultaneously, we genetically linked the FSHβ- and CGβ-subunit genes to the common α-subunit, resulting in a single-chain protein that exhibited both activities in vitro. These studies also indicated that the bifunctional triple-domain variant (FSHβ-CGβ-α), is secreted as two distinct bioactive populations each corresponding to a single activity, and each bearing the heterodimer-like contacts. Although the data are consistent with the known secretion events of gonadotropins from the pituitary, we could not exclude the possibility whether transient intermediates are generated in vivo in which the α-subunit shuttles between the two β-subunits during early stages of accumulation in the endoplasmic reticulum. Therefore, constructs were engineered that would direct the synthesis of single-chain proteins completely devoid of heterodimer-like interactions but elicit both LH and FSH actions. These triple-domain, single-chain chimeras contain the FSHβ- and CGβ-subunits and an α-subunit with cystine bond mutations (cys10–60 or cys32–84), which are known to prevent heterodimer formation. Here we show that, despite disrupting the intersubunit interactions between the α- and both CGβ- and FSHβ-subunits, these mutated analogs exhibit both activities in vivo comparable to nonmutated triple-domain single chain. Such responses occurred despite the absence of quaternary contacts due to the disrupted bonds in the α-subunit. Thus, gonadotropin heterodimer assembly is critical for intracellular events, e.g. hormone-specific posttranslational modifications, but when heterodimers are present in the circulation, the α/β-contacts are not a prerequisite for receptor recognition.
Exploring the Chemistry and Biology of Antitumor Enediyne Chromoprotein C-1027
Authors: Inoue Masayuki 
Published: April 2006

Abstract
C-1027 is an extremely potent antitumor agent, and belongs to a family of chromoprotein antitumor antibiotics, which contain a carrier apoprotein and highly unstable enediyne chromophore. The enediyne spontaneously aromatizes to generate p-benzyne biradical, and subsequently abstracts hydrogens from the DNA sugar backbone, resulting in the sequence-selective double-strand cleavage. On the other hand, the C-1027 apoprotein functions as a carrier, and is likely to escort the reactive chromophore through the cells until reaching the target DNA. The excitement surrounding this molecule lies in the complex molecular architecture of the chromophore, the important biological activity, and the fascinating mode of action. In this account, our studies in the chemistry and biology of C-1027 are presented in three parts: (1) synthetic study of the C-1027 chromophore, (2) spin-trapping study of the C-1027-induced DNA cleavage, and (3) rational design of a kinetically stabilized analog of C-1027.
BDT-TTP-Based π Conductors Containing Divalent Magnetic and Non-Magnetic Inorganic Anions, [MIICl4]2− (M = Co, Mn, Zn)
Authors: Kusamoto Tetsuro , Fujiwara Emiko , Kobayashi Akiko , Cui Hengbo , Otsuka Takeo , Okano Yoshinori , Fujiwara Hideki , Kobayashi Hayao 
Published: April 2006

Abstract
Three BDT-TTP [2,5-bis(1,3-dithiol-2-ylidene)-1,3,4,6-tetrathiapentalene] salts, (BDT-TTP)3[MIICl4](EtOH)x (M = Co, Mn, and Zn; x ≈ 1.0) were prepared. These salts are almost isostructural to one another. The crystals are composed of BDT-TTP columns, “BDT-TTP tapes” that occupy the interstitial positions between BDT-TTP columns, [MIICl4]2− anions and the crystal solvents, respectively. These salts showed weakly metallic conducting behavior down to about 150 K. At low temperature, the resistivities increased gradually with decreasing temperature, but the systems retained fairly high conductivities even at around 30 K. The [ZnIICl4]2− salt indicated temperature independent paramagnetism down to low temperature. While the susceptibilities of the [CoIICl4]2− and [MnIICl4]2− salts showed the coexistence of π conduction electrons and localized high-spins of the magnetic CoII and MnII atoms, no significant π–d interaction was observed. Band structure calculations were performed with taking account of the possibility of inhomogeneous distribution of π electrons over the crystallographically independent three BDT-TTP molecules. The system has wide and narrow one-dimensional bands that originate from BDT-TTP columns and tapes, respectively. However, due to the interaction between BDT-TTP columns and tapes, the system gave a unique two-dimensional electronic band. The calculated energy dispersion curves were consistent with the weakly metallic behavior of the systems.
Anodic Cyanation of 1-Arylpyrrolidines
Authors: Liu Wei , Ma Yuan , Yin Yingwu , Zhao Yufen 
Published: April 2006

Abstract
The electrochemical cyanation of 1-arylpyrrolidines was carried out in methanol containing sodium cyanide at a platinum anode in a divided cell. The reaction gave the corresponding α-aminonitriles 2, together with the unexpected 1-arylpyrrolidine-2-carboximidic acid methyl esters 3 as byproducts.
Calcium-Binding Membrane Influence on Polymorph and Morphology of Calcium Carbonate Formed by Biomimetic Mineralization
Authors: Ichikawa Kazuhiko , Shimomura Noriyuki 
Published: April 2006

Abstract
The typical conclusions can be drawn as follows: (1) Since vaterite was only formed on calcium-binding poly(l-aspartate)-coated surface between 15 and 35 °C, the carbonic anhydrase (CA)-arising activity of zinc array (i.e., zinc-coordinated imidazolin-terminated silane monolayer, as shown in Chem. Eur. J.2003, 9, 3235) prevailed the temperature influence on the polymorph of calcium carbonate. Time evolution of calcium carbonate formation was enhanced by the zinc array. (2) The calcium carbonate crystallized only on imidazolin- and sulfonate-terminated silane membranes has shown a number of microspheres of 1 μm more or less in diameter. (3) The higher temperature and higher pH induced aragonite formation at the sulfonate-terminated Nafion membrane in the presence of the above zinc array. (4) The observed morphology of aragonite or vaterite was similar to the spherulitic aragonite or vaterite formed by biological mineralization in marine organisms.
Partitionings of Major-to-Ultratrace Elements in Bittern as Determined by ICP-AES and ICP-MS with Aid of Chelating Resin Preconcentration
Authors: Ji Shan , Zhu Yanbei , Yabutani Tomoki , Itoh Akihide , Haraguchi Hiroki 
Published: April 2006

Abstract
The concentrations of major-to-ultratrace elements in bittern, which was obtained after seawater concentration in the salt preparation process, were investigated by ICP-AES (inductively coupled plasma atomic emission spectrometry) and ICP-MS (inductively coupled plasma mass spectrometry) with and without the aid of chelating resin preconcentration. As a result, 34 elements in bittern could be determined in the concentration range from 107 to 10−3 ng mL−1 with good RSDs (less than 5%) for most analyte elements. Based on the experimental results, the concentrations of the elements in bittern were compared with those in seawater. Furthermore, the distribution factors of major-to-ultratrace elements in bittern were estimated to elucidate the partitionings of those elements among the calcium precipitate, the salt and the bittern from coastal seawater. The results suggest that the concentrations of the elements in bittern significantly depended on their chemical forms in seawater. For example, K and Mg in ionic form, V, Mo, W, and U in oxoanion form, and Cu and Zn in complex form with organic molecules in seawater, were much more partitioned in bittern than in salt.
Synthesis and Steady-State Spectroscopic Study of 5-Aryl-2,2′-bipyridyls. New Fluorescent Compounds in Solid State
Authors: Mizuyama Naoko , Tominaga Yoshinori , Kohra Shinya , Ueda Kazuo , Hirayama Shun-ichi , Shigemitsu Yasuhiro 
Published: April 2006

Abstract
The absorption and fluorescent properties of newly synthesized 5-aryl-2,2′-bipyridyls were examined both in solution and in the solid state. The 6-methoxy derivatives 5a–5c have weak fluorescence, whereas 6-amino derivatives 7a–7f showed strong fluorescence. Their spectroscopic properties were computationally analyzed using semi-empirical molecular orbital calculations. The geometries of the ground (S0) and the first singlet excitation states (S1) were optimized and employed to estimate the vertical transition energies. The drastic differences in fluorescent intensities between 5a–5c and 7a–7f can be qualitatively explained by the relative energy levels S1 and the neighboring triplet level; the energy gaps supposedly regulate the non-radiative intersystem crossing (ISC) probabilities. On the relaxed S1 geometry, 5a–5c have quite small S1–triplet energy gaps, whereas 7a–7f have no such quasi-degeneracies, leading to their quantitatively different quantum yields.
Synthesis and Characterization of Potential Efficient Electroluminescent Materials: 2-Phenyl-5-[4-(4-phenylamino-2H-1,2,3-triazol-2-yl)]phenyl-1,3,4-oxadiazole Derivatives
Authors: Zhou Jia-Xing , Wong Fung Fuh , Chen Chun-Yen , Yeh Mou-Yung 
Published: April 2006

Abstract
Recently, 1,3,4-oxadiazole-based on heterocyclic compounds were investigated as electroluminescent materials. In this work, we first introduce 1,2,3-triazole to synthesize a series of 1,3,4-oxadiazole–1,2,3-triazole hybrids derivatives as potential electroluminescent materials and explore the effect of modification of the 1,2,3-triazole moiety. The λmax values of the UV–vis of 1,3,4-oxadiazole–1,2,3-triazole hybrids are promoted to longer wavelengths (340–350 nm) than the traditional 1,2,3-triazole derivatives (280–330 nm) in solutions and have a bathochromic shift to 350–360 nm in THF solution. The λmax values of the photoluminescence (PL) spectra are in the range 406–480 nm in solutions. Compound 7h evaporated to form films on quartz substrates, had a maximum at 455 nm and showed a red-shift (≈40 nm) with respect to the solution spectrum. The solution fluorescence quantum yields (Φf) were measured, all of which fell into the range 0.65–0.76, and were determined relative to that of 2-phenyl-5-(4-biphenyl)-1,3,4-oxadiazole in benzene (Φf = 0.80). 1,3,4-Oxadiazole–1,2,3-triazole hybrids derivatives show unclearly reversible reduction processes in cyclic voltammogram measurements. Following spectroscopic studies and observation of the electrochemical behaviors, 1,3,4-oxadiazole–1,2,3-triazole derivatives were determined to be highly potential efficient blue electroluminescent materials.
Structural and Catalytic Properties of Silica-Coated Alumina
Authors: Sato Satoshi , Takahashi Ryoji , Sodesawa Toshiaki , Shin Daiji , Ichikawa Naoki , Ogura Katsuyuki 
Published: April 2006

Abstract
SiO2-coated Al2O3 powders were prepared by depositing hydrolyzed tetraethoxysilane (TEOS) on Al(OH)3 and γ-Al2O3 at 40 °C. In the preparation using Al(OH)3 with a specific surface area (SA) of ca. 40 m2 g−1 as a support, loading of silica deposited on the Al(OH)3 was saturated at 80 mg galumina−1. Ammonium nitrate, a catalyst for the hydrolysis of TEOS, increased silica loading linearly with increasing the amount of TEOS charged, while the silica aggregated on the Al(OH)3. At temperatures of &gt;300 °C, the core Al(OH)3 coated with aggregated silica was fragmented into a mixture of small particles of pure alumina and silica–alumina diminishing small particles with a large SA of &gt;400 m2 g−1. The small surface area of the support Al(OH)3 is ineffective in generating active acid sites. In the deposition of silica on γ-Al2O3 with a SA of 450 m2 g−1, however, silica loading increased with increasing the amount of TEOS charged at 40 °C without using ammonium nitrate. Silicate species with thinner layer structures uniformly covered the γ-Al2O3 surface. The SiO2-covered γ-Al2O3 showed higher catalytic activity than the SiO2–Al2O3 prepared from Al(OH)3 did.
Complex Impedance and Solid-State NMR Studies on a Novel High Proton Conductor Na-RUB-18
Authors: Ishimaru Shin’ichi , Togawa Maki , Ikeda Ryuichi , Shimizu Tadashi , Shinohara Emi , Umemura Yasushi 
Published: April 2006

Abstract
Measurements of complex impedance and 2H NMR spectra were performed on a layer silicate compound, Na-RUB-18 (sodium octosilicate, NaSi4O8(OH)·nH2O), to investigate hydrogen dynamics in crystals. A high proton conductivity amounting to ca. 10−1 S m−1 was observed at room temperature under 100% relative humidity. Activation energies of the proton conduction were estimated to be 125 and 18 kJ mol−1 below and above 290 K, respectively. 2H NMR spectra observed on a deuterated analog revealed 1-D proton conduction through hydrogen-bond networks formed among silanol groups on the layer surface and water molecules in the interlayer space. This material was discovered to be a new type of solid proton-conductor contributed by very weak acids in contrast to the strong-acid type ones so far reported.
Real-Time Nucleic Acid Sequence–Based Amplification Assay to Quantify Changes in Mitochondrial DNA Concentrations in Cell Cultures and Blood Cells from HIV-Infected Patients Receiving Antiviral Therapy
Authors: Timmermans Eveline C , Tebas Pablo , Ruiter Jos PN , Wanders Ronald JA , de Ronde Anthony , de Baar Michel P 
Published: April 2006

AbstractBackground: To study the clinical relevance of changes in mitochondrial DNA (mtDNA) in peripheral blood mononuclear cells (PBMCs) attributable to HIV infection and/or combination antiretroviral therapy (cART), a high-throughput molecular assay to quantify mtDNA is required.Methods: We developed a quantitative real-time duplex nucleic acid sequence–based amplification assay in which both mtDNA and nuclear DNA are simultaneously amplified in 1 tube. The assay could accurately quantify mtDNA in a range of 15–1500 copies of mtDNA per 2 genomic copies with an intrarun variation of 11% and an interrun variation of 16%. We compared this real-time assay with the lactate/pyruvate ratios in fibroblasts incubated with glucose and exposed to zalcitabine. Additionally, we studied the effects of platelet contamination and the in vivo effects of cART on mtDNA in PBMCs from a small group of patients.Results: Decreases in mtDNA preceded the increase in lactate/pyruvate ratios and vice versa when zalcitabine was eliminated from the culture. Platelets affected the mtDNA in PBMCs if &gt;5 platelets per PBMC were present. Within 12 weeks, mtDNA increased and remained increased in PBMCs from patients on continuous treatment with zidovudine/lamivudine/indinavir therapy (P = 0.03), but increased if patients were switched to stavudine/didanosine therapy (P = 0.008).Conclusion: After drug exposure, the mtDNA assay can detect changes in mtDNA concentrations in cell lines and PBMCs, when properly controlled for platelet effects, earlier than traditional assays.
Hepatorenal syndrome
Authors: Demırtaş Selda , Can Murat , Yarpuzlu Ayşegül 
Published: April 2006

AbstractThis article summarizes the literature on current definition, suggested pathogenetic mechanisms and the role of laboratory assessment in the differential diagnosis of hepatorenal syndrome (HRS) from other causes of renal disease that may arise during hepatic cirrhosis and some diseases affecting both liver and kidney. It should be remembered that the main theory suggested for the pathogenesis of HRS is the arterial vasodilation hypothesis of portal hypertension, ending in type 1 and type 2 HRS, but there is no consensus supporting either mechanism as a solid theory for initiation of HRS pathogenesis to date. No laboratory test can firmly establish a diagnosis of HRS, which is mainly based on the absence of any specific cause of renal failure. Laboratory and ultrasonographic tests based on non-invasive techniques are being investigated as possible diagnostic approaches.
Clinical relevance of biological variation: the lesson of brain natriuretic peptide (BNP) and NT-proBNP assay
Authors: Clerico Aldo , Carlo Zucchelli Gian , Pilo Alessandro , Passino Claudio , Emdin Michele 
Published: April 2006

AbstractThe clinical relevance of brain natriuretic peptide (BNP) and N-terminal (NT)-proBNP assays as a diagnostic tool and prognostic marker in patients with cardiovascular diseases has recently been confirmed. However, several studies demonstrated variation of intra-individual BNP concentrations of >30% (ranging from 30% to 50%) with reference change values at the 95% confidence interval (i.e., the estimated critical difference) ranging from 99% to 130% in healthy subjects and heart failure patients. According to this estimated confidence interval, only a great variation in plasma BNP levels should be considered significant in an individual patient (for example, a decrease of >50% or an increase of more than two-fold). Many recent clinical studies have demonstrated that BNP variations below this estimated critical difference could also have clinical relevance. Like the concentration of other neuro-hormones, levels of plasma BNP fluctuate widely and rapidly along with heart rhythm and blood pressure variations in response to physiological stimuli. However, biological variation of BNP should not be interpreted strictly as random fluctuation around a homeostatic set point, as assumed by the common model used in all studies on biological variation of BNP reported in the literature. These results cannot be directly transferred to clinical practice. While awaiting more accurate studies, we suggest that variations of plasma BNP three-fold greater than the analytical imprecision should be considered as potentially relevant from a physiological and clinical point of view.
Multicenter evaluation of the interference of hemoglobin, bilirubin and lipids on Synchron LX-20 assays
Authors: Steen Gerard , Vermeer Henricus J. , Naus André J.M. , Goevaerts Berrie , Agricola Pauline T. , Schoenmakers Christian H.H. 
Published: April 2006

AbstractThe influence of interference by hemolysis, icterus and lipemia on the results of routine chemistries may lead to wrong interpretations. The H-, I- and L-indices that can be measured by the Beckman LX-20 instrument (Beckman Coulter) in serum or plasma samples are a reliable semi-quantitative measure of the size of these interferences. A survey carried out in 16 Dutch clinical laboratories on the use of these indices demonstrated that in several of these laboratories, the influence of interferences is largely underestimated. Therefore, a multicenter study was carried out in which we examined the interference of hemolysis, icterus and lipemia on 32 analytes. On the basis of biological variation, we decided on cutoff indices above which analytically significant interference exists. We found analytically significant interference by hemolysis, icterus or lipemia, in 12, 7 and 15 of the 32 analytes studied, respectively. Flagging of results on the basis of analytically significant interference, however, results in too many clinically insignificant comments. On the basis of clinical significance, we conclude that significant interference by hemolysis, icterus or lipemia is present in only 5, 6 and 12 of the analytes studied, respectively. Use of the cutoff indices presented here facilitates optimal use of the LX-20 indices to prevent reporting of wrong results due to interference.