bluuebunny/crossref_metadata_2025 huggingface dataset:
The action of selection on codon bias in the human genome is related to frequency, complexity, and chronology of amino acids
Authors: Kotlar Daniel , Lavner Yizhar
Published: April 2006

Background

The question of whether synonymous codon choice is affected by cellular tRNA abundance has been positively answered in many organisms. In some recent works, concerning the human genome, this relation has been studied, but no conclusive answers have been found. In the human genome, the variation in base composition and the absence of cellular tRNA count data makes the study of the question more complicated. In this work we study the relation between codon choice and tRNA abundance in the human genome by correcting relative codon usage for background base composition and using a measure based on tRNA-gene copy numbers as a rough estimate of tRNA abundance.

Results

We term major codons to be those codons with a relatively large tRNA-gene copy number for their corresponding amino acid. We use two measures of expression: breadth of expression (the number of tissues in which a gene was expressed) and maximum expression level among tissues (the highest value of expression of a gene among tissues). We show that for half the amino acids in the study (8 of 16) the relative major codon usage rises with breadth of expression. We show that these amino acids are significantly more frequent, are smaller and simpler, and are more ancient than the rest of the amino acids. Similar, although weaker, results were obtained for maximum expression level.

Conclusion

There is evidence that codon bias in the human genome is related to selection, although the selection forces acting on codon bias may not be straightforward and may be different for different amino acids. We suggest that, in the first group of amino acids, selection acts to enhance translation efficiency in highly expressed genes by preferring major codons, and acts to reduce translation rate in lowly expressed genes by preferring non-major ones. In the second group of amino acids other selection forces, such as reducing misincorporation rate of expensive amino acids, in terms of their size/complexity, may be in action.

The fact that codon usage is more strongly related to breadth of expression than to maximum expression level supports the notion, presented in a recent study, that codon choice may be related to the tRNA abundance in the tissue in which a gene is expressed.
Prototypical antipsychotic drugs protect hippocampal neuronal cultures against cell death induced by growth medium deprivation
Authors: Bastianetto Stéphane , Danik Marc , Mennicken Françoise , Williams Sylvain , Quirion Rémi
Published: April 2006

Background

Several clinical studies suggested that antipsychotic-based medications could ameliorate cognitive functions impaired in certain schizophrenic patients. Accordingly, we investigated the effects of various dopaminergic receptor antagonists – including atypical antipsychotics that are prescribed for the treatment of schizophrenia – in a model of toxicity using cultured hippocampal neurons, the hippocampus being a region of particular relevance to cognition.

Results

Hippocampal cell death induced by deprivation of growth medium constituents was strongly blocked by drugs including antipsychotics (10-10-10-6 M) that display nM affinities for D2 and/or D4 receptors (clozapine, haloperidol, (±)-sulpiride, domperidone, clozapine, risperidone, chlorpromazine, (+)-butaclamol and L-741,742). These effects were shared by some caspases inhibitors and were not accompanied by inhibition of reactive oxygen species. In contrast, (-)-raclopride and remoxipride, two drugs that preferentially bind D2 over D4 receptors were ineffective, as well as the selective D3 receptor antagonist U 99194. Interestingly, (-)-raclopride (10-6 M) was able to block the neuroprotective effect of the atypical antipsychotic clozapine (10-6 M).

Conclusion

Taken together, these data suggest that D2-like receptors, particularly the D4 subtype, mediate the neuroprotective effects of antipsychotic drugs possibly through a ROS-independent, caspase-dependent mechanism.
Progressive neurological disease induced by tacrolimus in a renal transplant recipient: Case presentation
Authors: Chegounchi Marjan , Hanna Michael G , Neild Guy H
Published: April 2006

Background

Tacrolimus and cyclosporine, both calcineurin inhibitors, can cause neurological side effects. While mild symptoms such as tremor are well recognised, severe complications including seizures and encephalopathy are poorly documented following renal transplantation.

Case presentation

We report a 42 year old man who received a cadaver renal transplant. He received tacrolimus and prednisolone. The course was uneventful for 6 weeks when he became intermittently confused, with unsteady gait and slurred speech. Following a grand mal convulsion he was admitted. He had no focal neurological signs, cerebrospinal fluid was normal; electroencephalogram was consistent with temporal lobe partial epilepsy. The magnetic resonance imaging of brain showed widespread changes with multiple areas of low signal intensity in brain stem and cerebral hemispheres. He was readmitted 3 weeks later after further fits, despite anti-convulsant therapy. He was psychotic with visual hallucinations, and rapidly became obtunded. Although his tacrolimus blood concentration had been kept in the normal range, his symptoms improved dramatically when the tacrolimus was stopped.

Conclusion

Severe central nervous system toxicity from calcineurin inhibitors has been rarely reported in renal transplantation and we found only one report of tacrolimus-induced toxicity in an adult. We believe the condition is frequently undiagnosed. It is a very important diagnosis not to miss as the remedy is simple and failure may result in unnecessary brain biopsy, as well as irreversible injury.
Acute health effects of the Tasman Spirit oil spill on residents of Karachi, Pakistan
Authors: Janjua Naveed Zafar , Kasi Pashtoon Murtaza , Nawaz Haq , Farooqui Sadia Zohra , Khuwaja Urooj Bakht , Najam-ul-Hassan  , Jafri Syed Nadim , Lutfi Shahid Ali , Kadir Muhammad Masood , Sathiakumar Nalini
Published: April 2006

Background

On July 27 2003, a ship carrying crude oil run aground near Karachi and after two weeks released 37,000 tons of its cargo into the sea. Oil on the coastal areas and fumes in air raised health concerns among people. We assessed the immediate health impact of oil spill from the tanker Tasman Spirit on residents of the affected coastline in Karachi, Pakistan.

Methods

We conducted a study consisting of an exposed group including adults living in houses on the affected shoreline and two control groups (A and B) who lived at the distance of 2 km and 20 km away from the sea, respectively. We selected households through systematic sampling and interviewed an adult male and female in each household about symptoms relating to eyes, respiratory tract, skin and nervous system, smoking, allergies, beliefs about the effect on their health and anxiety about the health effects. We used logistic regression procedures to model each symptom as an outcome and the exposure status as an independent variable while adjusting for confounders. We also used linear regression procedure to assess the relationship exposure status with symptoms score; calculated by summation of all symptoms.

Results

Overall 400 subjects were interviewed (exposed, n = 216; group A, n = 83; and group B, n = 101). The exposed group reported a higher occurrence of one or more symptoms compared to either of the control groups (exposed, 96% vs. group A, 70%, group B 85%; P < 0.001). Mean summary symptom scores were higher among the exposed group (14.5) than control group A (4.5) and control group B (3.8, P < 0.001). Logistic regression models indicated that there were statistically significant, moderate-to-strong associations (Prevalence ORs (POR) ranging from 2.3 to 37.0) between the exposed group and the symptoms. There was a trend of decreasing symptom-specific PORs with increase in distance from the spill site. Multiple linear regression model revealed strong relationship of exposure status with the symptoms score (β = 8.24, 95% CI: 6.37 – 10.12).

Conclusion

Results suggest that the occurrence of increased symptoms among the exposed group is more likely to be due to exposure to the crude oil spill.
Decreased intracellular zinc in human tumorigenic prostate epithelial cells: a possible role in prostate cancer progression
Authors: Huang Liping , Kirschke Catherine P , Zhang Yunfan
Published: April 2006

Background

Zinc plays important roles in maintaining normal function of the prostate and in development of prostate malignancy. It has been demonstrated that prostate malignant epithelial cells contain much less cellular zinc than the surrounding normal epithelial cells. However, the pathway(s) which leads to lower zinc accumulation in malignant prostate epithelial cells is poorly understood. In this study, the zinc homeostatic features of two human prostate epithelial cell lines (non-tumorigenic, RWPE1, and tumorigenic, RWPE2) were investigated. Effects of over-expression of ZIP1 in RWPE2 on cell proliferation and apoptosis were also studied.

Results

RWPE2 accumulated less intracellular zinc than RWPE1 due to the decreased zinc uptake activity. The mRNA expression of ZIP1 and ZIP3 in RWPE1 and RWPE2 was comparable. However, the protein expression of ZIP1 in RWPE2 was lower than that in RWPE1. ZIP3 was detected in a lysosomal compartment of RWPE2 while no ZIP3 was detected in the same compartment of RWPE1. Over-expression of ZIP1 in RWPE2 resulted in an elevation of intracellular zinc concentration and suppression of cell growth of RWPE2 due to the increased apoptosis.

Conclusion

These findings suggest that tumorigenic prostate epithelial cells accumulated less intracellular zinc than non-tumorigenic prostate epithelial cells. The reduction in capacity for accumulation of intracellular zinc in tumorigenic prostate epithelial cells may be caused by the decrease in the ZIP1 protein expression and the intracellular redistribution of ZIP3 in RWPE2. RWPE1 and RWPE2 are excellent cellular models to study the association of intracellular zinc levels with prostate cancer progression.
Internship workplace preferences of final-year medical students at Zagreb University Medical School, Croatia: all roads lead to Zagreb
Authors: Polasek Ozren , Kolcic Ivana , Dzakula Aleksandar , Bagat Mario
Published: April 2006

Background

Human resources management in health often encounters problems related to workforce geographical distribution. The aim of this study was to investigate the internship workplace preferences of final-year medical students and the reasons associated with their choices.

Method

A total of 204 out of 240 final-year medical students at Zagreb University Medical School, Croatia, were surveyed a few months before graduation. We collected data on each student's background, workplace preference, academic performance and emigration preferences. Logistic regression was used to analyse the factors underlying internship workplace preference, classified into two categories: Zagreb versus other areas.

Results

Only 39 respondents (19.1%) wanted to obtain internships outside Zagreb, the Croatian capital. Gender and age were not significantly associated with internship workplace preference. A single predictor variable significantly contributed to the logistic regression model: students who believed they would not get the desired specialty more often chose Zagreb as a preferred internship workplace (odds ratio 0.32, 95% CI 0.12–0.86).

Conclusion

A strong preference for Zagreb as an internship workplace was recorded. Uncertainty about getting the desired specialty was associated with choosing Zagreb as a workplace, possibly due to more extensive and diverse job opportunities.
Innate immune functions of microglia isolated from human glioma patients
Authors: Hussain S Farzana , Yang David , Suki Dima , Grimm Elizabeth , Heimberger Amy B
Published: April 2006

Background

Innate immunity is considered the first line of host defense and microglia presumably play a critical role in mediating potent innate immune responses to traumatic and infectious challenges in the human brain. Fundamental impairments of the adaptive immune system in glioma patients have been investigated; however, it is unknown whether microglia are capable of innate immunity and subsequent adaptive anti-tumor immune responses within the immunosuppressive tumor micro-environment of human glioma patients. We therefore undertook a novel characterization of the innate immune phenotype and function of freshly isolated human glioma-infiltrating microglia (GIM).

Methods

GIM were isolated by sequential Percoll purification from patient tumors immediately after surgical resection. Flow cytometry, phagocytosis and tumor cytotoxicity assays were used to analyze the phenotype and function of these cells.

Results

GIM expressed significant levels of Toll-like receptors (TLRs), however they do not secrete any of the cytokines (IL-1β, IL-6, TNF-α) critical in developing effective innate immune responses. Similar to innate macrophage functions, GIM can mediate phagocytosis and non-MHC restricted cytotoxicity. However, they were statistically less able to mediate tumor cytotoxicity compared to microglia isolated from normal brain. In addition, the expression of Fas ligand (FasL) was low to absent, indicating that apoptosis of the incoming lymphocyte population may not be a predominant mode of immunosuppression by microglia.

Conclusion

We show for the first time that despite the immunosuppressive environment of human gliomas, GIM are capable of innate immune responses such as phagocytosis, cytotoxicity and TLR expression but yet are not competent in secreting key cytokines. Further understanding of these innate immune functions could play a critical role in understanding and developing effective immunotherapies to malignant human gliomas.
Amphotropic murine leukemia virus is preferentially attached to cholesterol-rich microdomains after binding to mouse fibroblasts
Authors: Beer Christiane , Pedersen Lene
Published: April 2006

Background

We have recently shown that amphotropic murine leukemia virus (A-MLV) can enter the mouse fibroblast cell line NIH3T3 via caveola-dependent endocytosis. But due to the size and omega-like shape of caveolae it is possible that A-MLV initially binds cells outside of caveolae. Rafts have been suggested to be pre-caveolae and we here investigate whether A-MLV initially binds to its receptor Pit2, a sodium-dependent phosphate transporter, in rafts or caveolae or outside these cholesterol-rich microdomains.

Results

Here, we show that a high amount of cell-bound A-MLV was attached to large rafts of NIH3T3 at the time of investigation. These large rafts were not enriched in caveolin-1, a major structural component of caveolae. In addition, they are rather of natural occurrence in NIH3T3 cells than a result of patching of smaller rafts by A-MLV. Thus cells incubated in parallel with vesicular stomatitis virus glycoprotein (VSV-G) pseudotyped MLV particles showed the same pattern of large rafts as cells incubated with A-MLV, but VSV-G pseudotyped MLV particles did not show any preference to attach to these large microdomains.

Conclusion

The high concentration of A-MLV particles bound to large rafts of NIH3T3 cells suggests a role of these microdomains in early A-MLV binding events.
Suppression of adaptive immunity to heterologous antigens during Plasmodium infection through hemozoin-induced failure of dendritic cell function
Authors: Millington Owain R , Di Lorenzo Caterina , Phillips R Stephen , Garside Paul , Brewer James M
Published: April 2006

Background

Dendritic cells (DCs) are central to the initiation and regulation of the adaptive immune response during infection. Modulation of DC function may therefore allow evasion of the immune system by pathogens. Significant depression of the host's systemic immune response to both concurrent infections and heterologous vaccines has been observed during malaria infection, but the mechanisms underlying this immune hyporesponsiveness are controversial.

Results

Here, we demonstrate that the blood stages of malaria infection induce a failure of DC function in vitro and in vivo, causing suboptimal activation of T cells involved in heterologous immune responses. This effect on T-cell activation can be transferred to uninfected recipients by DCs isolated from infected mice. Significantly, T cells activated by these DCs subsequently lack effector function, as demonstrated by a failure to migrate to lymphoid-organ follicles, resulting in an absence of B-cell responses to heterologous antigens. Fractionation studies show that hemozoin, rather than infected erythrocyte (red blood cell) membranes, reproduces the effect of intact infected red blood cells on DCs. Furthermore, hemozoin-containing DCs could be identified in T-cell areas of the spleen in vivo.

Conclusion

Plasmodium infection inhibits the induction of adaptive immunity to heterologous antigens by modulating DC function, providing a potential explanation for epidemiological studies linking endemic malaria with secondary infections and reduced vaccine efficacy.
Antipituitary Antibodies Recognizing Growth Hormone (GH)-Producing Cells in Children with Idiopathic GH Deficiency and in Children with Idiopathic Short Stature
Authors: De Bellis Annamaria , Salerno Mariacarolina , Conte Marisa , Coronella Concetta , Tirelli Gilda , Battaglia Marina , Esposito Valentina , Ruocco Giuseppe , Bellastella Giuseppe , Bizzarro Antonio , Bellastella Antonio
Published: April 2006

Context: Antipituitary antibodies (APA) recognizing GH-secreting cells may indicate an autoimmune pituitary involvement in adults with idiopathic GH deficiency (IGHD).

Objective: We aimed 1) to investigate the presence of APA in prepubertal children with IGHD or idiopathic short stature (ISS), identifying the pituitary hormone-producing cells targeted by APA; and 2) to verify whether in patients with ISS the presence of APA could predict the development of GHD.

Design: We performed a cross-sectional and partially longitudinal cohort study.

Setting: The study was performed at the Endocrinology Unit and Pediatric Unit of the Second University and University Federico II of Naples, respectively.

Patients: Twenty-six children with IGHD (group 1), 60 children with ISS (group 2), 33 children with GHD caused by lesions/abnormalities of the hypothalamus or pituitary (group 3), and 40 controls participated in the study. Nineteen children of group 2 were reevaluated after 2 yr.

Main Outcome Measures: IGF-I levels, GH secretion, and APA (by indirect immunofluorescence) were evaluated in all participants.

Results: At study entry, APA recognizing GH-producing cells were detected in seven of 26 children in group 1 and in 14 of 60 in group 2. Two years later, all eight initially APA-positive and all 11 APA-negative of the 19 reevaluated patients persisted positive and negative, respectively. The reevaluation of GH secretion in these patients revealed the development of GHD in all but one of the APA-positive children but in none of the APA-negative ones.

Conclusions: IGHD in children can be frequently associated with APA targeting GH-secreting cells; thus, the detection of APA in children with ISS could identify those prone to develop GHD.
Facile Synthesis of α- Keto Carbonyl Compounds by Indirect Anodic Oxidation
Authors: Maekawa Hirofumi , Ishino Yoshio , Nishiguchi Ikuzo
Published: April 2006

Secondary alcohols having a carbonyl group at the neighboring carbon atom were electrochemically oxidized to the corresponding α-keto carbonyl compounds in good yields. Thus, aromatic α-hydroxyl esters were easily transformed to arylglyoxylates in excellent yields using an undivided cell while efficient anodic oxidation of α-hydroxyl ketones and aliphatic α-hydroxyl esters successfully proceeded in a divided cell to give the corresponding α-keto carbonyl compounds.
The Characteristics of the Fluorescence Spectra of Rhodamine B Molecules Doped in Si-Ti Binary Oxide System by the Sol-Gel Method
Authors: Negishi Nobuaki , Yamashita Hiromi , Anpo Masakazu
Published: April 2006

The characteristics of the fluorescence spectra of Rhodamine B (RhB) doped in Si-Ti binary oxide by the sol-gel method were measured as a function of Ti-content in the binary oxides. The RhB fluorescence in the Si-Ti binary oxide was only from the excited state of the monomer when the Ti-content in the Si-Ti binary oxide was low. On the other hand, the RhB dimer fluorescence was observed when the Ti-content in the Si-Ti binary oxide was high.
Oxidation of Ethers by NO3• Generated from NO3− with Anodic Oxidation
Authors: Shono Tatsuya , Yamamoto Yoshinari , Takigawa Katsuya , Maekawa Hirofumi , Ishifune Manabu , Kashimura Shigenori
Published: April 2006

A radical NO3• generated by anodic oxidation of NO3− was found to be an effective species to the oxidation of ethers to the corresponding carboxylic acids and ketones, and this reaction was successfully applied to the synthesis of dihydrojasmone.
Transition Metal Phosphine Complexes Possessing Phase Transfer Function. Preparation and Reactivities of Palladium Complexes Containing Quaternary Ammonium Groups
Authors: Okano Tamon , Harada Nobuyuki , Kiji Jitsuo
Published: April 2006

A new type of phosphine ligands (L) bearing quaternary ammonium as a functional group was synthesized. Their palladium complexes, PdBr2L2, readily underwent halogen exchange with powdered NaI under two-phase conditions, and efficiently catalyzed the fluorocarbonylation of phenyl bromide with powdered KF at atmospheric pressure of CO.
Total Synthesis of (−)-Pyrenophorin via Cobalt(II) Porphyrin-Catalyzed Oxygenation of Ethyl (2E,4E,7R)-7-Acetoxy-2,4-octadienoate
Authors: Matsushita Yoh-ichi , Furusawa Hiroshi , Matsui Takanao , Nakayama Mitsuru
Published: April 2006

(−)-Pyrenophorin was synthesized by the Mitsunobu reaction of (2E,7S)-4,4-ethylenedioxy-7-hydroxy-2-octenoic acid which has been prepared via cobalt(II) porphyrin-catalyzed oxygenation of ethyl (2E,4E,7S)-7-acetoxy-2,4-octadienoate.
Coupled Cyclodextrin Appending Imidazole as an Enzyme Model
Authors: Akiike Toshiyuki , Nagano Yuichi , Yamamoto Yukinori , Nakamura Asao , Ikeda Hiroshi , Ueno Akihiko , Toda Fujio
Published: April 2006

Novel imidazole-appended coupled β-cyclodextrin (6) was prepared by the condensation of 6-deoxy-6-(l-histidylamino)-β-cyclodextrin and 6-(carboxymethylthio)-6-deoxy-β-cyclodextrin with dicyclohexylcarbodiimide. The enzyme-like activities of 6 were studied by measuring the rates for the hydrolysis reaction of some kinds of p-nitrophenyl alkanoates (C2, C3, C6, and C12). 6 showed large acceleration ability and substrate specificity for only p-nitrophenyl C6 ester.
A New Approach to the Synthesis of γ-Hydroxy-α,β-unsaturated Macrolides and (−)-Pyrenophorin by Intramolecular C=C Bond Formation with Oxidative Functionalization from ω-[α-(p-Chlorophenylsulfinyl)acetoxy]alkanal
Authors: Nokami Junzo , Taniguchi Takuya , Gomyô Shintaro , Kakihara Toshio
Published: April 2006

The title compounds were prepared via the intramolecular condensation reaction of 12-[α-(p-chlorophenylsulfinyl)acetoxy]tridecanal(or dodecanal) or via the combination of inter- and intramolecular condensation of 5-[α-(p-chlorophenylsulfinyl)acetoxy]hexanal in the presence of piperidine.
Molecular Design of Calix[4]arene-Based Sodium-Selective Electrodes Which Show Remarkably High 105.0–105.3 Sodium/Potassium Selectivity
Authors: Yamamoto Hiromasa , Shinkai Seiji
Published: April 2006

Several ionophores for the Na+-selective electrode were developed from calix[4]arene crown ethers with a short –(CH2CH2O)2CH2CH2– crown loop on the lower rim. The ionophoric cavities generated in these ionophores are much smaller and more rigid than those derived from calix[4]arene crown ethers with a long –(CH2CH2O)3CH2CH2– crown loop. It was shown that two electrodes possess Na+ selectivity (with respect to K+) exceeding a factor of 105 which is higher by more than two orders of magnitude than that of the former calix[4]arene-based Na+-selective electrodes!
Time-Resolved Luminol Chemiluminescence for Simultaneous Determination of Cobalt(II) and Copper(II)
Authors: Kamidate Tamio , Ishikawa Atsushi , Segawa Tadashi , Watanabe Hiroto
Published: April 2006

The peroxidation of luminol was performed using both Co(II) and Cu(II) as a catalyst in the presence of cysteine. A luminol chemiluminescence (CL) catalyzed by Co(II) occurred instantly from the initiation of the reaction, whereas a Cu(II)-catalyzed luminol CL suddenly appeared after a dark period. The time-resolved luminol CL were applied for the simultaneous determination of Co(II) and Cu(II).
Molecular Oriented Thin Film of Biphenyl-4,4′-dithiol Fabricated by Molecular Beam Deposition Method
Authors: Tsumura Akira , Hamano Kouji , Fuchigami Hiroyuki , Kurata Tetsuyuki , Kohri Sachiko , Uehara Yasushi , Koezuka Hiroshi , Niino Hiroyuki , Yabe Akira
Published: April 2006

Biphenyl-4,4′-dithiol was deposited as a stacked molecular layer onto several kinds of substrates by a molecular beam deposition method. It was found that both the gold thin film and the potassium bromide (KBr) single crystal were effective substrates for the control of the molecular orientation and also that the lattice constants of the substrate were responsible for the control of crystallinity of biphenyl-4,4′-dithiol thin films.
A Heterotrimetallic Sulfide Cluster Having a Linear RhIII···WVI···CuI Framework of an Octahedral - Tetrahedral - Trigonal Planar Sequence
Authors: Ogo Seiji , Suzuki Takayoshi , Ozawa Yoshiki , Isobe Kiyoshi
Published: April 2006

A heterotrimetallic sulfide cluster with an organometallic group, [Cp*Rh{P(OEt)3}(μ-S)2W(μ-S)2CuCl] (Cp* = η5-C5Me5), was prepared stepwise by using mononuclear units of organorhodium(III), thiotungstate(VI), and chlorocopper(I). X-ray crystal structure analysis revealed that the cluster possesses a linear sequence of middle (Rh), early (W), and late (Cu) transition metal atoms with octahedral, tetrahedral, and trigonal planar coordination geometries, respectively.
Immobilization of the Ring Inversion Motion in Calix[6]arene by a Cap with C3-Symmetry
Authors: Araki Koji , Akao Kiyotaka , Otsuka Hideyuki , Nakashima Kazuaki , Inokuchi Fumiaki , Shinkai Seiji
Published: April 2006

A conformationally-immobilized calix[6]arene (2) was synthesized for the first time. The immobilization was attained by capping calix[6]aryl 1,3,5-tricarboxylic acid chloride with C3-symmetrical triol. The 1H NMR spectral examination with 2D EXSY established that 2 is immobilized in a cone conformation. Compound 2 showed the high affinity for guanidinium ion because of rigidification of the conformation.
Random and Block Copolymerization of Substituted Acetylenes Catalyzed by Tungsten μ-Hydride Complexes
Authors: Yamamoto Hidetoshi , Saito Yasuko , Nagase Yu , Fuchikami Takamasa
Published: April 2006

High molecular weight copolymers were obtained from 1-phenyl-1-propyne and monosubstituted acetylenes by coordination polymerization with tungsten μ-hydride complexes as catalysts in toluene as a solvent. The permeability coefficients of N2 and O2 through the membranes obtained from phenylacetylene/1-phenyl-1-propyne copolymers were evaluated.
Synthesis of 2,3,4,5-Tetra(2-thienyl)cyclopentadienone Exhibiting Considerable Substituent Effects and Synthetic Utility
Authors: Kawase Takeshi , Ohsawa Takeshi , Enomoto Tetsuya , Oda Masaji
Published: April 2006

2,3,4,5-Tetra(2-thienyl)cyclopentadienone and the related compounds, here first synthesized, show large bathochromic shift of visible absorptions and appreciably higher amphoteric redox properties than tetraphenylcyclopentadienone; 2-thienyl groups at 2,5-positions exert stronger substituent effects than those at 3,4-positions.
A Selective Fluorometric Sensing System for Guanidinium Ion in the Presence of Primary Ammonium Ions
Authors: Takeshita Michinori , Shinkai Seiji
Published: April 2006

Pyrene functionalized calix[6]arene selectively recognizes guanidinium ion in the presence of primary ammonium ions, the recognition process being detected by its intramolecular excimer fluorescence change: this is the first selective ‘reading-out’ system for guanidinium ion.
Synthesis and Reactions of a 2,5-Dithia-3,4-disilatitanacyclopentane
Authors: Choi Nami , Sugi Shin-ichiro , Ando Wataru
Published: April 2006

Lithium 1,2-di-tert-butyl-1,2-diphenyldisilane-1,2-dithiolate reacted with titanocene dichloride to afford cis-3,4-di-tert-butyl-3,4-diphenyl-2,5-dithia-3,4-disila-1-bis(cyclopentadienyl)titanacyclopentane (2), whose structure was determined by X-ray analysis. The titanacycle 2 is reacted with electrophilic reagents (SCl2, S2Cl2, PhPCl2, Ph2GeCl2) to afford the corresponding heterocycles in good yields.
Uniform-size Macroporous Polymer-based Stationary Phase for HPLC Prepared through Molecular Imprinting Technique
Authors: Hosoya Ken , Yoshizako Kimihiro , Tanaka Nobuo , Kimata Kazuhiro , Araki Takeo , Haginaka Jun
Published: April 2006

Uniform-size macroporous polymer-based stationary phase was prepared through molecular imprinting technique. Although the stationary phase was prepared by polymerization in an aqueous medium, template molecule was effectively imprinted onto the uniform-size macroporous polymer particles. The ability of chromatographic recognition toward the template molecule on the stationary phase was almost identical to that of the previously reported rod-type separation media1) with larger capacity factor.
Alkylation of Isobutane with Butenes Catalyzed by a Cesium Hydrogen Salt of 12-Tungstophosphoric Acid
Authors: Okuhara Toshio , Yamashita Masayuki , Na Kyutae , Misono Makoto
Published: April 2006

A solid superacid, Cs2.5H0.5PW12O40, catalyzed the alkylation of isobutane with butenes at room temperature. Cs2.5H0.5PW12O40 was much more active than SO42−/ZrO2, a well-known solid superacid, and was highly selective.
A New Chiral Stationary Phase Bearing Both π-Acidic and π-Basic Sites Derived from (S)-Tyrosine for the Liquid Chromatographic Resolution of Racemates
Authors: Hyun Myung Ho , Min Chung-Sik
Published: April 2006

A new chiral stationary phase (CSP) bearing both π-acidic and π-basic sites for the chiral liquid chromatography has been prepared from (S)-tyrosine. This CSP has been found to be useful in resolving a variety of either π-basic or π-acidic racemates.
Influence of Added Saccharides on the Conformation of Boronic-Acid-Appended Poly(l-lysine). Attempts to Control a Helix-Coil Transition by Sugars
Authors: Nagasaki Takeshi , Kimura Taro , Arimori Susumu , Shinkai Seiji
Published: April 2006

Poly(l- and d-lysine)s (l- and d-1, respectively) were modified with a phenylboronic acid derivative which acts as a sugar-binding site. When monosaccharides were added to the l-1 solution, the helix content was increased and the pH which gives the maximum helix content shifted to lower pH region. The pH dependence in the presence of d-fructose was different, although slightly, between l- and d-1. This is a novel attempt toward the control of a polypeptide conformation by sugars.
Enantioselective Catalysis by Supramolecular Bilayer Membrane as Artificial Aminotransferase
Authors: Kikuchi Jun-ichi , Zhang Zhi-Yi , Murakami Yukito
Published: April 2006

A supramolecular bilayer assembly, composed of a cationic peptide lipid having an l-histidyl residue, a hydrophobic pyridoxamine derivative, and copper(II) ions, performed substrate-selective catalysis as a vitamin B6-dependent artificial aminotransferase to transform α-keto acids into the corresponding α-amino acids in an enantiomeric excess of the d-isomer.
Highly-Sensitive Measurement of Dihydroxyphenols Using Carbon Felt Electrode Impregnated with Fructose Dehydrogenase-Containing Solution
Authors: Mizutani Fumio , Yabuki Soichi
Published: April 2006

A carbon felt electrode impregnated with a fructose dehydrogenase/fructose-containing solution was used for measuring dihydroxyphenols (e.g., catechol and dopamine). Dihydroxyphenol molecules are oxidized on the electrode but regenerated by the enzyme reaction. The consumption/regeneration cycle for dihydroxyphenols resulted in an amplified electrode response. Further, the measuring method could be free from the electrochemical interference by oxidizable species such as l-ascorbic acid.
An Investigation of the Ionic Polarization of Carrageenans with Different Charge Densities
Authors: Ueda Kazuyoshi , Sato Shigenobu , Ochiai Hiroshi , Imamura Akira , Yamaoka Kiwamu
Published: April 2006

Counterion polarization of κ-, ι- and λ-carrageenans, which have different charge densities, in aqueous solution was investigated through the electric birefringence method. The data analysis by the Manning’s counterion condensation theory suggests that the loosely bound counterions mainly contribute to the ionic polarization.
The Emission Cross Section of the Paschen-α Line Produced in Electron-Hydrogen Collisions
Authors: Ogawa Teiichiro , Yonekura Nobuaki , Kido Masami , Furuya Kenji , Nakashima Keiji
Published: April 2006

The Paschen-α line (1875.1 nm) of the excited hydrogen atom produced in e-H2 collisions was observed with a grating spectrometer equipped with a PbS detector. The emission cross section was determined to be 0.95 × 10−19 cm2 at 100 eV.
Effect of Cu(II) Ion on the Polycondensation of Octadecyl Esters of Aromatic Amino Acids in Monolayers at the Air/Water Interface
Authors: Liu Ming-hua , Nakahara Hiroo , Shibasaki Yoshio , Fukuda Kiyoshige
Published: April 2006

Polycondensation of octadecyl esters of l-phenylalanine (l-PheC18), l-tyrosine (l-TyrC18) and l-tryptophan (l-TrpC18) in the monolayers on the subphase containing Cu(II) ion was significantly accelerated in comparison with those in the monolayers on phosphate buffer or in bulk phases. A reaction mechanism including formation of an intermediate complex and reorientation of the aromatic rings was proposed.
Fluorometric and Coulometric Analyses of Electron Transfer across Microdroplet/Water Interface
Authors: Nakatani Kiyoharu , Chikama Katsumi , Kim Haeng-Boo , Kitamura Noboru
Published: April 2006

Electron transfer between ferrocene (FeCp) and Fe(III) across the droplet/water interface was studied by an optically transparent thin-layer electrode method. A time dependence of the FeCp concentration in the droplets caused by the interfacial electron transfer was discussed on the basis of coulometric analysis of Fe(II) or Fe(III) in the water phase and fluorometric analysis of FeCp in the droplets.
Energy-Transfer Luminescence of Lanthanide Ions Encapsulated in Calix[4]arenes. Correlation between the Energy Level of Sensitizers and the Quantum Yield
Authors: Matsumoto Hitoshi , Shinkai Seiji
Published: April 2006

It was shown that the Tb3+ and Eu3+ complexes of 5,11,17,23-tetraacetyl-25,26,27,28-tetrakis(N,N-diethylaminocarbonylmethoxy)calix[4]arene give the high luminescence quantum yields (Φ = 0.164 for Tb3+ and 0.017 for Eu3+). The mechanistic investigations established that the high quantum yields are due to the energy level suitable to the energy-transfer and the presence of the carbonyl groups which mediate the intersystem crossing.
Selective Alkylation of p-Xylene with 2-Methylpropene by 12-Tungstophosphoric Acid
Authors: Soeda Hironobu , Okuhara Toshio , Misono Makoto
Published: April 2006

Solid H3PW12O40 catalyzed the alkylation of p-xylene with 2-methylpropene to t-butyl-p-xylene with 75%-selectivity, while the selectivity with H2SO4 was only 7%. The selectivity of heteropolyacids tended to increase with the acid strength.
Co2 Abatement and Fuel Mix in German Electric Power Generation — Is the “Ecological Electricity Tax” Ecologically Effective?
Authors: Tauchmann Harald
Published: April 2006

This paper analyzes the effect of a potential carbon tax on inter-fuel substitution in the electric power sector in Germany. By analyzing firm level panel data (1980–1998), we show that the fuel mix as used by power plants is price inelastic. That means that differential fuel taxes, e.g. a carbon tax, will not induce inter-fuel substitution towards less carbon intensive fuels. This in turn means that the recent introduction in Germany of an electricity tax cannot be judged less effective than the hypothetical introduction of a carbon tax with respect to power related CO2 emissions. It is likely, however, that in the course of the deregulation of the German power sector a carbon tax will become significantly more effective than an electricity tax.
Use of Sildenafil for Female Sexual Dysfunction
Authors: Shields Kelly M , Hrometz Sandra L
Published: April 2006

Objective:

To review the pathophysiology of female sexual dysfunction (FSD) and the literature regarding the use of sildenafil in its treatment.

Data Sources:

Literature was accessed through MEDLINE (1966—April 2006), Iowa Drug Information Service (1966—April 2006), EMBASE (1966—April 2006), and bibliographies of pertinent articles. Search terms included female sexual dysfunction; sexual dysfunction, psychological; phosphodiesterase inhibitors; and sildenafil.

Data Synthesis:

The lack of a clear understanding of FSD contributes to the limited treatment options available. Studies regarding the safety and efficacy of the phosphodiesterase 5 inhibitor sildenafil in the management of FSD were evaluated. Many trials have been of poor quality, making clinical application of their results difficult. The current literature does not show sildenafil to be an effective treatment option for FSD.

Conclusions:

Treatment of FSD should include both physical and psychological components. Based on the limited data available, it appears that sildenafil, while well tolerated, offers little or no benefit to most patients with FSD.
Pathway-Specific Bidirectional Regulation of Ca2+/Calmodulin-Dependent Protein Kinase II at Spinal Nociceptive Synapses after Acute Noxious Stimulation
Authors: Larsson Max , Broman Jonas
Published: April 2006

An intensely painful stimulus may lead to hyperalgesia, the enhanced sensation of subsequent painful stimuli. This is commonly believed to involve facilitated transmission of sensory signals in the spinal cord, possibly by a long-term potentiation-like mechanism. However, plasticity of identified synapses in intact hyperalgesic animals has not been reported. Here, we show, using neuronal tracing and postembedding immunogold labeling, that after acute noxious stimulation (hindpaw capsaicin injections), immunolabeling of Ca2+/calmodulin-dependent protein kinase II (CaMKII) and of CaMKII phosphorylated at Thr286/287(pCaMKII) are upregulated postsynaptically at synapses established by peptidergic primary afferent fibers in the superficial dorsal horn of intact rats. In contrast, postsynaptic pCaMKII immunoreactivity was instead downregulated at synapses of nonpeptidergic primary afferent C-fibers; this loss of pCaMKII immunolabel occurred selectively at distances greater than ∼20 nm from the postsynaptic membrane and was accompanied by a smaller reduction in total CaMKII contents of these synapses. Both pCaMKII and CaMKII immunogold labeling were unaffected at synapses formed by presumed low-threshold mechanosensitive afferent fibers. Thus, distinct molecular modifications, likely indicative of plasticity of synaptic strength, are induced at different populations of presumed nociceptive primary afferent synapse by intense noxious stimulation, suggesting a complex modulation of parallel nociceptive pathways in inflammatory hyperalgesia. Furthermore, the activity-induced loss of certain postsynaptic pools of autophosphorylated CaMKII at previously unmanipulated synapses supports a role for the kinase in basal postsynaptic function.
Ambient GABA Constrains the Strength of GABAergic Synapses at Cajal-Retzius Cells in the Developing Visual Cortex
Authors: Kirmse Knut , Kirischuk Sergei
Published: April 2006

At early stages of brain development, GABA plays a dual role. It fulfills important trophic functions and provides a major excitatory drive for the immature neuronal network. Here, we investigated whether GABA itself can limit the strength of excitatory GABAergic synapses on Cajal-Retzius (CR) cells in sagittal slices from the mouse visual cortex. (2S)-3-[[(1S)-1-(3,4-dichlorophenyl)ethyl]amino-2-hydroxypropyl](phenylmethyl)phosphinic acid (CGP55845), a specific GABABreceptor (GABABR) blocker, increased the frequency of spontaneous Ca2+transients and spontaneous and miniature IPSCs (mIPSCs) but did not affect mIPSC amplitudes or kinetics.CGP55845significantly increased evoked IPSC (eIPSC) amplitudes and decreased the paired-pulse ratio (PPR). Baclofen, a specific GABABR agonist, produced opposite effects. The size of the readily releasable pool was not affected by these GABABR modulators. The sameCGP55845actions were observed at physiological temperatures, but they were abolished after glutamate decarboxylase block with 3-mercaptopropionic acid (3-MP). These results indicate that presynaptic GABABRs dynamically regulate GABA release probability. SNAP-5114, a specific GABA transporter-2/3 (GAT-2/3) blocker, enhanced mIPSC frequencies, decreased PPR, and increased eIPSC amplitudes without changing eIPSC kinetics. These effects were blocked byCGP55845and 3-MP. NO-711, a specific GAT-1 blocker, prolonged eIPSC decay and decreased eIPSC/mIPSC amplitudes. These NO-711-mediated effects were not sensitive toCGP55845and 3-MP. We conclude that the strength of GABAergic inputs to CR cells is constrained by GABABRs that are persistently activated by ambient GABA. The latter is also provided by GAT-2/3 operating in the reversed mode. Presynaptic GAT-1 functions in the uptake mode and possibly provides GABA for presynaptic vesicle filling.
Contribution of the Monkey Frontal Eye Field to Covert Visual Attention
Authors: Wardak Claire , Ibos Guilhem , Duhamel Jean-René , Olivier Etienne
Published: April 2006

The frontal eye field (FEF) has long been regarded as a cortical area critically involved in the execution of voluntary saccadic eye movements. However, recent studies have suggested that the FEF may also play a role in orienting attention. To address this issue, we reversibly inactivated the FEF using multiple microinjections of muscimol, a GABAAagonist, in two macaque monkeys performing visually guided saccades to a single target. The effects of FEF inactivation were also studied in a covert visual search task that required monkeys to search for a target presented among several distractors without making any eye movements.

As expected, inactivating the FEF caused spatially selective deficits in executing visually guided saccades, but it also altered the ability to detect a visual target presented among distractors when no eye movements were permitted. These results allow us to conclude definitively to an involvement of the FEF in both oculomotor and attentional functions. Comparison of the present results with a similar experiment conducted in the lateral intraparietal cortex area revealed qualitatively different deficits, suggesting that the two areas may make distinct contributions to selective attention processes.
Isolating the Modulatory Effect of Expectation on Pain Transmission: A Functional Magnetic Resonance Imaging Study
Authors: Keltner John R. , Furst Ansgar , Fan Catherine , Redfern Rick , Inglis Ben , Fields Howard L.
Published: April 2006

We use a novel balanced experimental design to specifically investigate brain mechanisms underlying the modulating effect of expected pain intensity on afferent nociceptive processing and pain perception. We used two visual cues, each conditioned to one of two noxious thermal stimuli [∼48°C (high) or 47°C (low)]. The visual cues were presented just before and during application of the noxious thermal stimulus. Subjects reported significantly higher pain when the noxious stimulus was preceded by the high-intensity visual cue. To control for expectancy effects, for one-half of the runs, the noxious thermal stimuli were accompanied by the cue conditioned to the other stimulus. Comparing functional magnetic resonance imaging blood oxygenation level-dependent activations produced by the high and low thermal stimulus intensities presented with the high-intensity visual cue showed significant activations in nociceptive regions of the thalamus, second somatosensory cortex, and insular cortex. To isolate the effect of expectancy, we compared activations produced by the two visual cues presented with the high-intensity noxious thermal stimulus; this showed significant differences in the ipsilateral caudal anterior cingulate cortex, the head of the caudate, cerebellum, and the contralateral nucleus cuneiformis (nCF). We propose that pain intensity expectancy modulates activations produced by noxious stimuli through a distinct modulatory network that converges with afferent nociceptive input in the nCF.
Why Does the Brain Predict Sensory Consequences of Oculomotor Commands? Optimal Integration of the Predicted and the Actual Sensory Feedback
Authors: Vaziri Siavash , Diedrichsen Jörn , Shadmehr Reza
Published: April 2006

When the brain initiates a saccade, it uses a copy of the oculomotor commands to predict the visual consequences: for example, if one fixates a reach target, a peripheral saccade will produce an internal estimate of the new retinal location of the target, a process called remapping. In natural settings, the target likely remains visible after the saccade. So why should the brain predict the sensory consequence of the saccade when after its completion, the image of the target remains visible? We hypothesized that in the post-saccadic period, the brain integrates target position information from two sources: one based on remapping and another based on the peripheral view of the target. The integration of information from these two sources could produce a less variable target estimate than is possible from either source alone. Here, we show that reaching toward targets that were initially foveated and remapped had significantly less variance than reaches relying on peripheral target information. Furthermore, in a more natural setting where both sources of information were available simultaneously, variance of the reaches was further reduced as predicted by integration. This integration occurred in a statistically optimal manner, as demonstrated by the change in integration weights when we manipulated the uncertainty of the post-saccadic target estimate by varying exposure time. Therefore, the brain predicts the sensory consequences of motor commands because it integrates its prediction with the actual sensory information to produce an estimate of sensory space that is better than possible from either source alone.
β-Amyloid Accumulation Impairs Multivesicular Body Sorting by Inhibiting the Ubiquitin-Proteasome System
Authors: Almeida Claudia G. , Takahashi Reisuke H. , Gouras Gunnar K.
Published: April 2006

Increasing evidence links intraneuronal β-amyloid (Aβ42) accumulation with the pathogenesis of Alzheimer’s disease (AD). In Aβ precursor protein (APP) mutant transgenic mice and in human AD brain, progressive intraneuronal accumulation of Aβ42occurs especially in multivesicular bodies (MVBs). We hypothesized that this impairs the MVB sorting pathway. We used the trafficking of the epidermal growth factor receptor (EGFR) and TrkB receptor to investigate the MVB sorting pathway in cultured neurons. We report that, during EGF stimulation, APP mutant neurons demonstrated impaired inactivation, degradation, and ubiquitination of EGFR. EGFR degradation is dependent on translocation from MVB outer to inner membranes, which is regulated by the ubiquitin-proteasome system (UPS). We provide evidence that Aβ accumulation in APP mutant neurons inhibits the activities of the proteasome and deubiquitinating enzymes. These data suggest a mechanism whereby Aβ accumulation in neurons impairs the MVB sorting pathway via the UPS in AD.