bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Solution Stirring on Protein Crystal Growth
Authors: Yaoi Mari , Aadachi Hiroaki , Takano Kazufumi , Matsumura Hiroyoshi , Inoue Tsuyoshi , Mori Yusuke , Sasaki Takatomo
Published: February 2005

We report the influence of solution stirring on the growth of hen egg white lysozyme crystals. Solution stirring rate was controlled by varying the rotation speed of a rotary shaker. A range of precipitation agent (sodium chloride) concentrations was also investigated. The time required for crystal nucleation to occur was observed to be much greater in stirred samples than in unstirred samples. Solution stirring resulted in a reduced number of crystals (at sodium chloride concentrations from 6 to 9%). These crystals were larger and of a higher quality. However, the time required for nucleation to occur was reduced by gentle stirring (25 and 50 rpm) in a 12.5% sodium chloride concentration solution, suggesting that stirring can stimulate nucleation. These results indicate that the optimization of solution stirring rates is a useful technique for controlling protein crystal growth.
Doping Study on Maskless Selective Direct Growth of GaAs Using Low-Energy Focused Ion Beam
Authors: Nishiyama Tomokazu , Kim Eum-Mi , Numata Kazutoshi , Pak Kangsa
Published: February 2005

We introduced a new growth/doping method for selective areas and demonstrated the in situ maskless selective doping of GaAs films using a low-energy focused ion beam. This in situ growth and doping method is thought to be essential in maskless selective device fabrication. In our experiment the in situ doping of n-GaAs and p-GaAs was conducted successfully. The crystalline quality and resistivity of the films showed good results at an incident ion beam energy of 30–60 eV. The Hall mobility of Sn-doped GaAs films was 2170 cm2·V-1·s-1 at a carrier concentration of 2.7 ×1017 cm-3, and that of Be-doped GaAs films was 49.1 cm2·V-1·s-1 at a carrier concentration of 1.19 ×1018 cm-3. In this experiment, the possibility of maskless selective microdevice fabrication was presented.
Effect of Low Temperature Thin GaN Layer on ZnO Film Grown on Nitridated c-Sapphire by Molecular Beam Epitaxy
Authors: Wang Xinqiang , Tomita Yosuke , Roh Ok-hwan , Ishitani Yoshihiro , Yoshikawa Akihiko
Published: February 2005

A low-temperature thin GaN layer was used to wet the grown ZnO buffer layer effectively in the epitaxy of a ZnO film on a nitridated c-sapphire substrate by plasma-assisted molecular beam epitaxy. An atomically smooth Zn-polar ZnO epilayer was achieved with an rms roughness of 0.13 nm in a 3 µm ×3 µm scanned area. Triangular terraces with monolayer steps (0.26 nm) were observed by atomic force microscope. The crystalline quality of the ZnO epilayer was also improved with the full width at half maximum (FWHM) values for (002) and (102) ω-scans of 41 arcsec and 378 arcsec, respectively.
Observation of Blowing out in Low Loss Passive Optical Fuse Formed in Silica Glass Optical Fiber Circuit
Authors: Todoroki Shin-ichi , Inoue Satoru
Published: February 2005

Low loss (less than 1dB) passive optical fuses were realized by inserting 50-µm-thick TeO2 glass layer into a single-mode silica glass fiber circuit with carbon coating. On the basis of real-time observation of their fusing action, the mechanism of losing its transparency is discussed. The observed loss drop is found to be an overlap of decoupling of the circuit and transient light flux from the burned coating. The critical input power to blow out is expected to be raised by eliminating its insertion loss.
Nanoimprint Lithography Using Novolak-Type Photoresist and Soft Mold at Room Temperature
Authors: Numai Takahiro , Koide Takeshi , Minemoto Takashi , Takakura Hideyuki , Hamakawa Yoshihiro
Published: February 2005

Nanoimprint lithography using novolak-type photoresist and a soft mold was successfully demonstrated. Two-dimensional square gratings with the pitch of 1000 nm and height of 300 nm formed on a polyester sheet were transferred onto novolak-type photoresist by combining pressing and successive developing of the novolak-type photoresist. By using the patterned novolak-type photoresist as an etching mask, a thermally oxidized 320-nm-thick SiO2 layer on a Si substrate was etched by reactive ion etching with CHF3 gas. Through this fabrication process, holes with the radius of 450 nm and depth of 320 nm were obtained on the thermally oxidized 320-nm-thick SiO2 layer.
Current-Induced Magnetization Reversal in a (Ga,Mn)As-Based Magnetic Tunnel Junction
Authors: Moriya Rai , Hamaya Kohei , Oiwa Akira , Munekata Hiro
Published: February 2005

We report current-induced magnetization reversal in a ferromagnetic semiconductor-based magnetic tunnel junction (Ga,Mn)As/AlAs/(Ga,Mn)As prepared by molecular beam epitaxy on a p-GaAs(001) substrate. A change in magneto-resistance that is asymmetric with respect to the current direction is found with the excitation current of 106 A/cm2. Contributions of both unpolarized and spin-polarized components are examined, and we conclude that the partial magnetization reversal occurs in the (Ga,Mn)As layer of smaller magnetization with the spin-polarized tunneling current of 105 A/cm2.
New Semiconductor GaNAsBi Alloy Grown by Molecular Beam Epitaxy
Authors: Yoshimoto Masahiro , Huang Wei , Takehara Yuji , Saraie Junji , Chayahara Akiyoshi , Horino Yuji , Oe Kunishige
Published: February 2005

GaN
y
As1-x-y
Bi
x
epilayers were grown on GaAs by molecular beam epitaxy for the first time. Multilayered samples consisting of GaAs1-x
Bi
x
, GaN
y
As1-y
and GaN
y
As1-x-y
Bi
x
showed distinct X-ray diffraction (XRD) peaks ascribed to each layer. The GaBi molar fraction, x, estimated by the combination of Rutherford backscattering spectroscopy and XRD was controlled in a range up to 4.0%. The GaN molar fraction estimated from the angular spacing of the XRD peak between GaAs1-x
Bi
x
and GaN
y
As1-x-y
Bi
x
increased up to 8.0% with increasing supply of activated nitrogen generated in rf plasma.
Pyroelectricity in Polyurea Thin Film with Oligothiophene Segments in the Main Chain Prepared by Vapor Deposition Polymerization
Authors: Muguruma Hitoshi , Ishikawa Masatoshi , Nakada Jumpei , Hotta Shu , Takahashi Yoshikazu
Published: February 2005

A new polyurea thin film with oligothiophene segments in the main chain was fabricated in the form of a thin film by vapor deposition polymerization (VDP). The film was prepared by the reaction between 5,5'''-bis(aminomethyl)-2,2':5',2'':5'',2'''-quaterthiophene (BAQ) and 4,4'-diphenylmethane diisocyanate (MDI). Spectroscopic data indicate that the reaction occurs successfully and that the resulting thin film is orientated by corona poling. Because of the high crystallinity of the oligothiophene backbone, the film shows a high and stable pyroelectricity (26–220 µC/m2·K) at 40–150°C compared with other aromatic polyurea films prepared by VDP and conventional bulk polymer such as polyvinylidene fluoride.
Enhanced Photodynamic Effect by the Assistance of Nanosecond-Pulsed-Laser-Induced Stress Wave
Authors: Terakawa Mitsuhiro , Sato Shunichi , Kawauchi Satoko , Ashida Hiroshi , Obara Minoru
Published: February 2005

We demonstrated that phototoxicity was enhanced by applying a single nanosecond-pulsed-laser-induced stress wave (LISW) to cultured cells before photodynamic treatment. Observation with a confocal laser scanning microscope showed that the enhanced phototoxicity is attributable to the larger cellular uptake of a photosensitizer due to the effect of LISW. It was also confirmed that the application of LISW alone did not reduce the cell viability.
Application of Fission Track Technique for the Analysis of Individual Particles Containing Uranium in Safeguard Swipe Samples
Authors: Esaka Konomi T. , Esaka Fumitaka , Inagawa Jun , Iguchi Kazunari , Lee Chi-Gyu , Sakurai Satoshi , Watanabe Kazuo , Usuda Shigekazu
Published: February 2005

An effective method for isotope ratio analysis of individual particles containing uranium in safeguard swipe samples was developed by using a fission track (FT) technique combined with thermal ionization mass spectrometry (TIMS). The particles in the sample were directly recovered onto a polycarbonate membrane filter, which was set in a filtration system. After the particle recovery, the filter was dissolved to form a non coated FT detector film containing the particles. Individual particles containing uranium were then identified by the observation of fission tracks created by thermal neutron irradiation. By combining the FT technique with TIMS, isotope ratios of uranium for individual particles in the swipe sample prepared from a uranium standard reference material could be effectively determined.
Gain-Clamped Double-Pass L-Band Erbium-Doped Fiber Amplifier Using A Ring Laser and Fiber Bragg Grating
Authors: Harun Sulaiman Wadi , Ahmad Harith
Published: February 2005

A highly efficient gain-clamped long-wavelength-band erbium-doped fiber amplifier (L-band EDFA) using a ring laser in a double-pass system is demonstrated. A broadband fiber Bragg grating (FBG) operating in the L-band region is used to retro-pass the test signal into the system to enhance the gain. The forward conventional-band (C-band) amplified spontaneous emission passes through the FBG and is routed to the input end of the amplifier via a C/L-band wavelength-selective coupler (WSC) so as to create a laser for gain clamping. The gain is clamped at 16.3 dB in the input power range from -40 to -8 dBm with a gain variation of less than ±0.2 dB at a variable optical attenuator setting of 12 dB. However, the noise figure is relatively high in the proposed amplifier due to the incorporation of a C/L-band WSC and a FBG.
Time-Resolved Photoluminescence Study of Si/β-FeSi2/Si Structures Grown by Molecular Beam Epitaxy
Authors: Suemasu Takashi , Takauji Motoki , Li Cheng , Ozawa Yoshinori , Ichida Masao , Hasegawa Fumio
Published: February 2005

Si/β-FeSi2 particles/Si(001) and Si/β-FeSi2 film/Si(111) structures were grown by reactive deposition epitaxy (RDE) and by molecular beam epitaxy (MBE), and time-resolved photoluminescence (PL) was measured from 8 K to 150 K. Both samples exhibited the same PL peak wavelength of 1.54 µm at low temperatures, but the PL decay time of 1.54 µm emission was different, showing that the luminescence originated from different sources. A short decay time (τ∼10 ns) was found to be dominant for the Si/β-FeSi2 particles/Si(001) at low temperatures. In contrast, the decay curve of the Si/β-FeSi2 film/Si(111) was well fitted by assuming a two-component model, with a short decay time (τ∼10 ns) and a long decay time (τ∼100 ns).
Unusual Phosphorescence Characteristics of Ir(ppy)3 in a Solid Matrix at Low Temperatures
Authors: Goushi Kenichi , Kawamura Yuichiro , Sasabe Hiroyuki , Adachi Chihaya
Published: February 2005

We observed unusual radiative decay characteristics of a (fac-tris(2-phenylpyridine)iridium [Ir(ppy)3]) triplet-excited state doped into 4, 4'-N, N'-dicarbazole-biphenyl (CBP) and polymethylmethacrylate (PMMA) host matrices. From a measurement of the temperature dependence on the phosphorescence intensity and the lifetime of Ir(ppy)3 in these hosts, we observed that phosphorescence intensities are independent of temperature, while the lifetimes significantly increase at temperatures below T ∼50 K. These results lead us to conclude that the non-radiative transition rate (k
nr) from the triplet excited state is very small compared with the radiative transition rate (k
r) and that the phosphorescence quantum yield (φPH) is nearly 100% even at room temperature. Based on our experimental results, we propose a possible decay mechanism to rationalize the characteristic temperature dependence on the transient phosphorescence.
Protein Crystallization Using a High-Repetitive Low-Power Laser Beam Under Tightly Focused Condition
Authors: Watanabe Shu , Nagasaka Shinobu , Noda Kohki , Tashiro Hideo
Published: February 2005

The feasibility of a simple laser irradiation scheme that utilizes a low-power laser beam emitted directly from a femtosecond laser oscillator was studied using lysozyme as an example for promoting protein crystallization. The various irradiation intensities required for crystallization promotion were surveyed by the hanging drop crystallization method under a tightly focused condition. The optimal irradiation condition was found to be 10 GW/cm2, and the rate of lysozyme crystallization increased five times compared with that for the nonirradiated sample. On the other hand, when an intensity of 45 GW/cm2 was applied, polycrystals were generated; the rate of crystallization was low with irradiation less than 5 GW/cm2.
Position-Selected Molecular Ruler
Authors: Tanaka Hirofumi , Anderson Mary E. , Horn Mark W. , Weiss Paul S.
Published: February 2005

The molecular ruler method allows the precise control of the gap between a parent gold structure and a deposited daughter structure using a conveniently grown self-assembled molecular multilayer as a lithographic mask. However, we cannot choose a position where the gap should be placed, since the ruler attaches to all exposed gold surfaces. In this work, a convenient method of selecting the position of nanogaps by further patterning the molecular multilayer using low-energy electron beam irradiation and piranha etchant is described.
Characteristic of the Si(100) Surface Low-Temperature Phase with Two Competing Structures Investigated by Rare Gas Adsorption
Authors: Kimura Tomohiko , Yoshida Shoji , Takeuchi Osamu , Matsuyama Eiji , Oigawa Haruhiro , Shigekawa Hidemi
Published: February 2005

The change of the Si(100) surface, exposed to Kr gas at 10 K with the scanning tunneling microscopy (STM) tip being extracted, was observed by STM. For a n-type sample, a p(2 ×2)/c(4 ×2) coexisting structure was stably observed even at low Kr coverage, and the amount of the c(4 ×2) area increased with increasing the coverage. These results clearly show the appearance of the p(2 ×2) phase at 10 K. The Kr growth process was observed by low-energy electron diffraction measurement for both n- and p-type samples, suggesting the influence of the STM measurement on the c(4 ×2) structure observed for the p-type sample at 10 K.
Ion Production Enhancement by Rear-Focusing and Prepulse in Ultrashort-Pulse Laser Interaction with Foil Targets
Authors: Wada Yoshio , Shigemoto Yasuo , Ogata Atsushi
Published: February 2005

It was found that the maximum ion energy produced in ultrashort-pulse laser interaction with foil targets is enhanced by a factor of five when the target is positioned before the focal point of the laser and the laser is accompanied by prepulses. A model is proposed in which the prepulse ablates the surface of the target. The resultant neutral gas guides the head of the main pulse by the Kerr effect. This finding opens up the possibility of MeV proton production by a TW-class laser.
SEA-0400, a potent inhibitor of the Na+/Ca2+ exchanger, as a tool to study exchanger ionic and metabolic regulation
Authors: Beaugé Luis , DiPolo Reinaldo
Published: February 2005

The effects of a new, potent, and selective inhibitor of the Na+/Ca2+ exchange, SEA-0400 (SEA), on steady-state outward (forward exchange), inward (reverse exchange), and Ca2+/Ca2+ transport exchange modes were studied in internally dialyzed squid giant axons from both the extra- and intracellular sides. Inhibition by SEA takes place preferentially from the intracellular side of the membrane. Its inhibition has the following characteristics: it increases synergic intracellular Na+ (Nai+) + intracellular H+ (Hi+) inactivation, is antagonized by ATP and intracellular alkalinization, and is enhanced by intracellular acidification even in the absence of Na+. Inhibition by SEA is still present even after 1 h of its removal from the experimental solutions, whereas removal of the cointeracting agents of inhibition, Nai+ and Hi+, even in the continuous presence of SEA, releases inhibition, indicating that SEA facilitates the reversible attachment of the natural Hi+ and Nai+ synergic inhibitors. On the basis of a recent model of squid Na+/Ca2+ exchange regulation (DiPolo R and Beaugé L. J Physiol 539: 791–803, 2002), we suggest that SEA acts on the Hi+ + Nai+ inactivation process and can interact with the Na+-free and Na+-bound protonized carrier. Protection by ATP concurs with the antagonism of the nucleotide by Hi+ + Nai+ synergic inhibition.
Satellite cells and utrophin are not directly correlated with the degree of skeletal muscle damage in mdx mice
Authors: Yamane Akira , Akutsu Satonari , Diekwisch Thomas G. H. , Matsuda Ryoichi
Published: February 2005

To determine whether muscle satellite cells and utrophin are correlated with the degree of damage in mdx skeletal muscles, we measured the area of the degenerative region as an indicator of myofiber degeneration in the masseter, gastrocnemius, soleus, and diaphragm muscles of mdx mice. Furthermore, we analyzed the expression levels of the paired box homeotic gene 7 ( pax7), m-cadherin (the makers of muscle satellite cells), and utrophin mRNA. We also investigated the immunolocalization of m-cadherin and utrophin proteins in the muscles of normal C57BL/10J (B10) and mdx mice. The expression level of pax7 mRNA and the percentage of m-cadherin-positive cells among the total number of cell nuclei in the muscle tissues in all four muscles studied were greater in the mdx mice than in the B10 mice. However, there was no significant correlation between muscle damage and expression level for pax7 mRNA ( R = −0.140), nor was there a correlation between muscle damage and the percentage of satellite cells among the total number of cell nuclei ( R = −0.411) in the mdx mice. The expression level of utrophin mRNA and the intensity of immunostaining for utrophin in all four muscles studied were greater in the mdx mice than in the B10 mice. However, there also was not a significant correlation between muscle damage and expression level of utrophin mRNA ( R = 0.231) in the mdx mice, although upregulated utrophin was incorporated into the sarcolemma. These results suggest that satellite cells and utrophin are not directly correlated with the degree of skeletal muscle damage in mdx mice.
In vivo functional NMR imaging of resistance artery control
Authors: Carlier P. G. , Bertoldi D.
Published: February 2005

Arterial spin labeling (ASL) in combination with NMR imaging is an in vivo technique that quantifies tissue perfusion in absolute values (ml blood·min−1·g tissue−1) with high temporal (1–10 s) and spatial (0.1–3 mm) resolution. It uses the arterial water spins as endogenous freely diffusible markers of perfusion and, hence, is a totally noninvasive method. The technique has been successfully applied to quantify baseline perfusion in many organs, including the heart, in humans and animals, and results were validated by comparison with gold standards, PET and microspheres, respectively. Because of the high sampling rate of perfusion with ASL and the possibility that measurements could be obtained without harm over indefinite periods of time, the technique has the potential for use in functional investigations of microcirculation regulation and resistance artery control in vivo. We describe examples of the use of ASL to this end. With use of specific technological developments, ASL determination of perfusion can be coupled with simultaneous acquisitions of 1H and 31P NMR spectroscopy data. These protocols offer new possibilities whereby the microcirculatory control of cell oxygenation and high-energy phosphate metabolism can be explored.
Neurons in the Rostral Cingulate Motor Area Monitor Multiple Phases of Visuomotor Behavior With Modest Parametric Selectivity
Authors: Hoshi Eiji , Sawamura Hiromasa , Tanji Jun
Published: February 2005

We examined the cellular activity in the rostral cingulate motor area (CMAr) with respect to multiple behavioral factors that ranged from the retrieval and processing of associative visual signals to the planning and execution of instructed actions. We analyzed the neuronal activity in monkeys while they performed a behavioral task in which 2 visual instruction cues were given successively with an intervening delay. One cue instructed the location of the target to be reached; the other cue instructed which arm was to be used. After a second delay, the monkey received a motor-set cue to be prepared to initiate the motor task in accordance with instructions. Finally, after a go signal, the monkey reached for the instructed target with the instructed arm. We found that the activity of neurons in the CMAr changed profoundly throughout the behavioral task, which suggested that the CMAr participated in each of the behavioral processing steps. However, the neuronal activity was only modestly selective for the spatial location of the visual signal. We also found that selectivity for the instructional information delivered with the signals (target location and arm use) was modest. Furthermore, during the motor-set and movement periods, few CMAr neurons exhibited selectivity for such motor parameters as the location of the target or the arm to be used. The abundance and robustness of the neuronal activity within the CMAr that reflected each step of the behavioral task and the modest selectivity of the same cells for sensorimotor parameters are strikingly different from the preponderance of selectivity that we have observed in other frontal areas. Based on these results, we propose that the CMAr participates in monitoring individual behavioral events to keep track of the progress of required behavioral tasks. On the other hand, CMAr activity during motor planning may reflect the emergence of a general intention for action.
Use of a recombinant Salmonella enterica serovar Typhimurium strain expressing C-Raf for protection against C-Raf induced lung adenoma in mice
Authors: Gentschev Ivaylo , Fensterle Joachim , Schmidt Andreas , Potapenko Tamara , Troppmair Jakob , Goebel Werner , Rapp Ulf R
Published: February 2005

Background

Serine-threonine kinases of the Raf family (A-Raf, B-Raf, C-Raf) are central players in cellular signal transduction, and thus often causally involved in the development of cancer when mutated or over-expressed. Therefore these proteins are potential targets for immunotherapy and a possible basis for vaccine development against tumors. In this study we analyzed the functionality of a new live C-Raf vaccine based on an attenuated Salmonella enterica serovar Typhimurium aroA strain in two Raf dependent lung tumor mouse models.

Methods

The antigen C-Raf has been fused to the C-terminal secretion signal of Escherichia coli α-hemolysin and expressed in secreted form by an attenuated aroA Salmonella enterica serovar Typhimurium strain via the α-hemolysin secretion pathway. The effect of the immunization with this recombinant C-Raf strain on wild-type C57BL/6 or lung tumor bearing transgenic BxB mice was analyzed using western blot and FACS analysis as well as specific tumor growth assays.

Results

C-Raf antigen was successfully expressed in secreted form by an attenuated Salmonella enterica serovar Typhimurium aroA strain using the E. coli hemolysin secretion system. Immunization of wild-type C57BL/6 or tumor bearing mice provoked specific C-Raf antibody and T-cell responses. Most importantly, the vaccine strain significantly reduced tumor growth in two transgenic mouse models of Raf oncogene-induced lung adenomas.

Conclusions

The combination of the C-Raf antigen, hemolysin secretion system and Salmonella enterica serovar Typhimurium could form the basis for a new generation of live bacterial vaccines for the treatment of Raf dependent human malignancies.
Glutamate Transporter: An Unexpected Target for Some Antibiotics
Authors: Mao Jianren
Published: February 2005

Glutamate transporter (GT) plays a major role in the mechanisms of glutamate homeostasis. Can this transporter system be a therapeutic target for glutamate-mediated neurological disorders? In January's edition of Nature, Rothstein et al (2005) reports that the most commonly used class of antibiotics (β-lactam antibiotics) such as ceftriaxone promoted the expression of GLT1 and demonstrated a functional role in both in vitro and in vivo models of glutamate neurotocixity. These findings indicate that positive promoters of GT expression may have a unique role in neuroprotection through regulating GT expression. This is also encouraging in search for new pharmacological tools for pain management.
Increased Glutamate Synaptic Transmission in the Nucleus Raphe Magnus Neurons from Morphine-Tolerant Rats
Authors: Bie Bihua , Pan Zhizhong Z
Published: February 2005

Currently, opioid-based drugs are the most effective pain relievers that are widely used in the treatment of pain. However, the analgesic efficacy of opioids is significantly limited by the development of tolerance after repeated opioid administration. Glutamate receptors have been reported to critically participate in the development and maintenance of opioid tolerance, but the underlying mechanisms remain unclear. Using whole-cell voltage-clamp recordings in brainstem slices, the present study investigated chronic morphine-induced adaptations in glutamatergic synaptic transmission in neurons of the nucleus raphe magnus (NRM), a key supraspinal relay for pain modulation and opioid analgesia. Chronic morphine significantly increased glutamate synaptic transmission exclusively in one class of NRM cells that contains μ-opioid receptors in a morphine-tolerant state. The adenylyl cyclase activator forskolin and the cAMP analog 8-bromo-cAMP mimicked the chronic morphine effect in control neurons and their potency in enhancing the glutamate synaptic current was significantly increased in neurons from morphine-tolerant rats. MDL12330a, an adenylyl cyclase inhibitor, and H89, a protein kinase A (PKA) inhibitor, reversed the increase in glutamate synaptic transmission induced by chronic morphine. In addition, PMA, a phorbol ester activator of protein kinase C (PKC), also showed an increased potency in enhancing the glutamate synaptic current in these morphine-tolerant cells. The PKC inhibitor GF109203X attenuated the chronic morphine effect. Taken together, these results suggest that chronic morphine increases presynaptic glutamate release in μ receptor-containing NRM neurons in a morphine-tolerant state, and that the increased glutamate synaptic transmission appears to involve an upregulation of both the cAMP/PKA pathway and the PKC pathway. This glutamate-mediated activation of these NRM neurons that are thought to facilitate spinal pain transmission may contribute to the reduced opioid analgesia during opioid tolerance.
DrosophilaN-cadherin functions in the first stage of the two-stage layer-selection process of R7 photoreceptor afferents
Authors: Ting Chun-Yuan , Yonekura Shinichi , Chung Phoung , Hsu Shu-ning , Robertson Hugh M. , Chiba Akira , Lee Chi-Hon
Published: February 2005

Visual information received from the three types of photoreceptor neurons(R1-R6, R7 and R8) in the fly compound eyes converges to the external part of the medulla neuropil (M1-M6 layers) in a layer-specific fashion: R7 and R8 axons terminate at the M6 and M3 layers, respectively, whereas lamina neurons(L1-L5) relay R1-R6 to multiple medulla layers (M1-M5). Here, we show that during development, R7 and R8 neurons establish layer-specific projections in two separate stages: during the first stage, R7 and R8 axons sequentially target to the R7- and R8-temporary layers, respectively; and at the second stage, R7 and R8 growth cones progress synchronously to their destined layers. Using a set of mutations that delete different afferent subsets or alter R7 connectivity, we defined the mechanism of layer selection. We observed that R8, R7 and L1-L5 afferents target to their temporary layers independently,suggesting that afferent-target, but not afferent-afferent, interactions dictate the targeting specificity. N-cadherin is required in the first stage for R7 growth cones to reach and remain in the R7-temporary layer. The Ncad gene contains three pairs of alternatively spliced exons and encodes 12 isoforms. However, expressing a single Ncad isoform in Ncad mutant R7s is sufficient to rescue mistargeting phenotypes. Furthermore, Ncad isoforms mediate promiscuous heterophilic interactions in an in vitro cell-aggregation assay. We propose that Ncad isoforms do not form an adhesion code; rather, they provide permissive adhesion between R7 growth cones and their temporary targets.
Shield formation at the onset of zebrafish gastrulation
Authors: Montero Juan-Antonio , Carvalho Lara , Wilsch-Bräuninger Michaela , Kilian Beate , Mustafa Chigdem , Heisenberg Carl-Philipp
Published: February 2005

During vertebrate gastrulation, the three germ layers, ectoderm, mesoderm and endoderm are formed, and the resulting progenitor cells are brought into the positions from which they will later contribute more complex tissues and organs. A core element in this process is the internalization of mesodermal and endodermal progenitors at the onset of gastrulation. Although many of the molecules that induce mesendoderm have been identified, much less is known about the cellular mechanisms underlying mesendodermal cell internalization and germ layer formation.

Here we show that at the onset of zebrafish gastrulation, mesendodermal progenitors in dorsal/axial regions of the germ ring internalize by single cell delamination. Once internalized, mesendodermal progenitors upregulate E-Cadherin (Cadherin 1) expression, become increasingly motile and eventually migrate along the overlying epiblast (ectodermal) cell layer towards the animal pole of the gastrula. When E-Cadherin function is compromised,mesendodermal progenitors still internalize, but, with gastrulation proceeding, fail to elongate and efficiently migrate along the epiblast,whereas epiblast cells themselves exhibit reduced radial cell intercalation movements. This indicates that cadherin-mediated cell-cell adhesion is needed within the forming shield for both epiblast cell intercalation, and mesendodermal progenitor cell elongation and migration during zebrafish gastrulation.

Our data provide insight into the cellular mechanisms underlying mesendodermal progenitor cell internalization and subsequent migration during zebrafish gastrulation, and the role of cadherin-mediated cell-cell adhesion in these processes.
Capturing Knowledge within and across Firm Boundaries: Evidence from Clinical Development
Authors: Azoulay Pierre
Published: February 2005

How do firm boundaries influence employees' acquisition of information? Using detailed project-level data and qualitative evidence, I document that pharmaceutical firms are more likely to outsource the coordination of data-intensive clinical trials, while they are more likely to assign knowledge-intensive trials to internal teams. Managers do not choose between market and hierarchy, but between the hierarchy of the firm—in which subjective performance evaluations are combined with flat explicit incentives—and the hierarchy of its subcontractor—whose virtue stems precisely from the ability to provide high-powered incentives on a narrow set of monitorable tasks.
The relationship between service intensity and the quality of health care: an exploratory data analysis
Authors: Friesner Daniel , Rosenman Robert
Published: February 2005

This paper provides an empirical check of some assumptions used to define the quality of care in the health services literature. Specifically, we test (i) whether service intensity is the only important determinant of a provider's quality and (ii) whether higher service intensity always causes higher quality. Using a panel of hospitals from Washington State, we find evidence that rejects both of these assumptions. As a result, further work is needed to postulate a more general definition that does not rely on these assumptions.
RNA polymerase II synthesizes antisense RNA in Plasmodium falciparum
Authors: MILITELLO KEVIN T. , PATEL VISHAL , CHESSLER ANNE-DANIELLE , FISHER JULIA K. , KASPER JACOB M. , GUNASEKERA ANUSHA , WIRTH DYANN F.
Published: February 2005

The recent identification of antisense RNA in the transcriptomes of many eukaryotes has generated enormous interest. The presence of antisense RNA in Plasmodium falciparum, the causative agent of severe malaria, remains controversial. Elucidation of the mechanism of antisense RNA in P. falciparum synthesis is critical in order to demonstrate the origin and function of these transcripts. Therefore, a systematic analysis of antisense and sense RNA synthesis was performed using direct labeling experiments. Nuclear run on experiments with single-stranded DNA probes demonstrated that antisense RNA is synthesized in the nucleus at several genomic loci. Antisense RNA synthesis is sensitive to the potent RNA polymerase II inhibitor α-amanitin. Antisense and sense transcription was also detected in nuclei isolated from synchronized parasites, suggesting concurrent synthesis. In summary, our experiments directly demonstrate that antisense RNA synthesis is a common transcriptional phenomenon in P. falciparum, and is catalyzed by RNA polymerase II.
Combining a Fatigue Model With a Shock Response Spectrum Algorithm
Authors: Daum MP
Published: February 2005

Product fragility assessment in packaging is described using a Damage Boundary Curve (DBC), which evaluates the velocity change and deceleration of an input shock for its damage potential to a product. The DBC assumes a brittle characteristic of components. A more realistic model is to assume ductility of components, resulting in something called Fatigue Damage Boundary (FDB) curves, which incorporate not only velocity change and deceleration, but also number of cycles to failure. The purpose of this study was to incorporate a mathematical model that accounts for the ductile nature of many products into a Shock Response Spectrum (SRS) algorithm. The advantage of incorporating SRS with a fatigue model is the ability to use any shock pulse shape to generate FDB curves and to use any shock pulse shape for finding material properties of a component in question. Using any shape shock pulse eliminates the dependency on traditional shock tables (half-sine and trapezoidal shock pulse shapes). Software was developed to demonstrate the new SRS-fatigue algorithm and to verify its applicability.
Knowledge, Attitude and Practices Related to Occupational Health Problems among Salt Workers Working in the Desert of Rajasthan, India
Authors: Haldiya Kripa Ram , Sachdev Raman , Mathur Murli L. , Saiyed Habibulla N.
Published: February 2005

Knowledge, Attitude and Practices Related to Occupational Health Problems among Salt Workers Working in the Desert of Rajasthan, India: Kripa Ram Haldiya, et al. Desert Medicine Research Centre (ICMR), India—Workers in the salt industry are exposed to direct sunlight, salt dust and contact with brine. To assess their awareness, attitude and practices related to occupational health problems, 205 salt workers were interviewed about health hazards and problems related to their working conditions, usage of protective measures and suggestions for their improvisation. The brine workers had a fair knowledge of their occupational health problems (98.7%), protective measures (100.0%) and their benefits (100.0%) as compared to non brine workers for whom these figures were 89.0%, 85.8% and 78.7% respectively. The brine workers (29.5%) and non brine workers (31.5%) used unconventional measures to prevent contact with salty water, salt dust, raw salt and glare. There was a huge gap between their knowledge and practice with protective devices, though they suggested improvements in protective devices to increase their acceptability.
Generating neuronal diversity in the Drosophila central nervous system: A view from the ganglion mother cells
Authors: Karcavich Rachel E.
Published: February 2005

The generation of cellular diversity in the developing embryonic central nervous system of Drosophila melanogaster requires the precise orchestration of several convergent molecular and cellular mechanisms. Most reviews have focused on the formation and specification of neuroblasts (NBs), the putative neural stem cell in the Drosophila central nervous system. NBs divide asymmetrically to regenerate themselves and produce a secondary precursor cell called a ganglion mother cell (GMC), which divides to produce neurons and glia. Historically, our understanding of GMC specification has arisen from work involving asymmetric localization of intrinsic factors in the NB and GMC. However, recent information on NB lineages has revealed additional intrinsic factors that specify general and specific GMC fates. This review addresses what has been revealed about these intrinsic cues with regard to GMC specification. For example, Prospero, an asymmetrically localized determinant, plays a general role to enable GMC development and to distinguish GMCs from NBs. In contrast, the temporal gene cascade functions within NB lineages to ensure that each GMC in a lineage acquires a different fate. Two different mechanisms used to make the progeny of GMCs different will also be discussed. One is a generic mechanism, regulated by Notch and Numb, that allows sibling cells to adopt different fates. The other mechanism involves genes, such as even‐skipped and klumpfuss that specify the fate of individual GMCs. All of these mechanisms converge within a GMC to bestow upon it a unique fate. Developmental Dynamics 232:609–616, 2005. © 2005 Wiley‐Liss, Inc.
Subcellular imaging mass spectrometry of brain tissue
Authors: McDonnell Liam A. , Piersma Sander R. , Altelaar A. F. Maarten , Mize Todd H. , Luxembourg Stefan L. , Verhaert Peter D. E. M. , van Minnen Jan , Heeren Ron M. A.
Published: February 2005

Imaging mass spectrometry provides both chemical information and the spatial distribution of each analyte detected. Here it is demonstrated how imaging mass spectrometry of tissue at subcellular resolution can be achieved by combining the high spatial resolution of secondary ion mass spectrometry (SIMS) with the sample preparation protocols of matrix‐assisted laser desorption/ionization (MALDI). Despite mechanistic differences and sampling 105 times less material, matrix‐enhanced (ME)‐SIMS of tissue samples yields similar results to MALDI (up to m/z 2500), in agreement with previous studies on standard compounds. In this regard ME‐SIMS represents an attractive alternative to polyatomic primary ions for increasing the molecular ion yield. ME‐SIMS of whole organs and thin sections of the cerebral ganglia of Lymnaea stagnalis demonstrate the advantages of ME‐SIMS for chemical imaging mass spectrometry. Subcellular distributions of cellular analytes are clearly obtained, and the matrix provides an in situ height map of the tissue, allowing the user to identify rapidly regions prone to topographical artifacts and to deconvolute topographical losses in mass resolution and signal‐to‐noise ratio. Copyright © 2005 John Wiley & Sons, Ltd.
Phase Behavior and Mechanical Properties of Mixed Poly(ethylene glycol) Mono‐Dodecyl Ether Aqueous Solutions
Authors: Yamazaki Ritsuko , Iizuka Kenichi , Hiraoka Kazuyuki , Nose Takuhei
Published: February 2005

Summary: The phase behavior and mechanical properties of mixed aqueous solutions of poly(ethylene glycol) mono‐dodecyl ether (C12E25) (the number of ethylene glycol units is about 25) and octa‐(ethylene glycol) mono‐dodecyl ether (C12E8) at 50 wt.‐% of the total concentration (C12E25 + C12E8) have been investigated by means of viscoelastic and thermal measurements and small‐angle X‐ray scattering. The phase behavior as a function of C12E25 composition (ϕC12E25) was divided into three regions. The C12E8‐rich gel region (0 < ϕC12E25 < 0.4) showed a hexagonal liquid crystalline phase of cylindrical micelles. The C12E25‐rich gel region (0.8 < ϕC12E25 < 1) included a body‐centered cubic phase of spherical micelles and the intermediate region (0.4 < ϕC12E25 < 0.8) with fluidity included disordered one‐phase and two‐phase regions. The cylindrical hexagonal ordered structure was maintained against the incorporation of C12E25 over a wide range of ϕC12E25, while the cubic lattice structure easily became unstable on addition of C12E25.

The C12E8‐rich gel solution had a lower elastic modulus with a relatively high loss modulus, while the gel in the C12E25‐rich region had a higher modulus and was more elastic with low values of the loss tangent. The stress‐strain curves observed showed that the C12E8 gel had no yield point but demonstrated a very broad peak with no steady flow in the experimental time range, while the C12E25 gel showed a yield point, followed by a steady plastic flow. The C12E25‐rich solution recovered its rheological properties which were distorted by pre‐shear deformation faster than the C12E8‐rich gel did.

These findings are discussed in terms of differences in the ordered structure between the cylindrical and spherical micellar gels with mixed shorter and longer corona chains.

SAXS profiles of C12E25‐C12E8 aqueous solutions.

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SAXS profiles of C12E25‐C12E8 aqueous solutions.
Recent developments in the ion/ion chemistry of high‐mass multiply charged ions
Authors: Pitteri Sharon J. , McLuckey Scott A.
Published: February 2005

The ability to form multiply charged high‐mass ions in the gas‐phase, most notably via electrospray ionization (ESI), has allowed the study of many different combinations of positively and negatively charged ions. The charged products are directly amenable to study with mass spectrometry. Ion/ion reactions have proved to be “universal” in the sense that the high exothermicities and large rate constants associated with essentially any combination of oppositely charged ions lead to reaction regardless of the chemical functionalities associated with the ions. These characteristics make ion/ion reactions potentially analytically useful provided reagent ion densities and spatial overlap of the oppositely charged ions are high. These conditions can be readily met by several instrumental configurations. The focus of this review is to highlight developments in this field since 1998. Novel instrumentation has been developed to study ion/ion reactions, such as atmospheric pressure ion/ion reactors followed by mass analysis, or electrodynamic ion trap mass spectrometers, which are used as reaction vessels at sub‐atmospheric pressures. A wide variety of reaction phenomenologies have been observed in various ion/ion reactions, with proton transfer being the most common. New phenomenologies have been observed in the reactions of multiply charged positive ions with singly charged negative ions, including cation transfer and cation exchange. A new series of reactions between multiply charged positive ions and multiply charged negative ions have been made possible by recent instrumentation developments. These reactions have led to the observation of proton transfer and complex formation. These observations have provided new insights into ion/ion reaction dynamics and a bound orbit model appears to best account for experimental results. New applications are also discussed for a several ion/ion reaction. © 2005 Wiley Periodicals, Inc., Mass Spec Rev 24:931–958, 2005
Study of high‐efficiency corrugated hard‐horn antennas using classical approaches: Hard circular waveguide mode, phase factor, and aperture integration
Authors: Sotoudeh Omid , Kildal Per‐Simon , Sipus Zvonimir
Published: February 2005

In this paper, a classical‐type approach is used to analyze the hard horn antenna. The quasi‐TEM mode in the longitudinally corrugated cylindrical waveguide is found by using the homogenized asymptotic boundary conditions. The finite horn length is accounted for by including a phase factor in the waveguide‐aperture fields, and the radiation patterns are finally obtained by aperture integration. The bandwidth is found to be much wider than previously anticipated with respect to low cross‐polarization. Also, an advanced mode‐matching code has been used for verification of the aperture field and the radiation patterns obtained with the much faster classical model. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 44: 516–523, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20684
β‐endorphin decreases fatigue and increases glucose uptake independently in normal and dystrophic mice
Authors: Khan Salim , Evans Anthony A. L. , Hughes Sharon , Smith Margaret E.
Published: February 2005

β‐Endorphin and a C‐terminal analogue have been shown to decrease muscle fatigue and increase glucose uptake in muscles of normal mice. In order to provide evidence whether these peptides might be useful in muscle‐wasting conditions and whether the two actions of the peptides are interdependent, the effect of β‐endorphin on muscle fatigue and glucose uptake was studied using isolated hemidiaphragm preparations of dystrophic mice as well as normal mice. Muscle contractions were elicited by high‐frequency stimulation of the phrenic nerve. Glucose uptake was measured using (nonmetabolizable) 2‐deoxy‐D‐[1‐3H]glucose. β‐Endorphin and the C‐terminal analogue reduced fatigue in normal muscles of males but not females. Insulin had no effect in either sex. The peptides increased 2‐deoxyglucose uptake in contracting and noncontracting muscles of normal males and females. β‐Endorphin reduced fatigue and increased deoxyglucose uptake in dystrophic muscles. The effect on fatigue was not due to increased glucose uptake, as the energy substrate present was pyruvate. Nerve stimulation released β‐endorphin immunoreactivity from intramuscular nerves of dystrophic mice. It is hypothesized that β‐endorphin released from motor nerves as well as from the pituitary could be responsible for improving muscle function during exercise. β‐Endorphin or analogues could have therapeutic use in muscle‐wasting disease. Muscle Nerve, 2005
Comparative interactomics
Authors: Cesareni Gianni , Ceol Arnaud , Gavrila Caius , Palazzi Luisa Montecchi , Persico Maria , Schneider Maria Victoria
Published: February 2005

The behavior, morphology and response to stimuli in biological systems are dictated by the interactions between their components. These interactions, as we observe them now, are therefore shaped by genetic variations and selective pressure. Similar to what has been achieved by comparing genome structures and protein sequences, we hope to obtain valuable information about systems’ evolution by comparing the organization of interaction networks and by analyzing their variation and conservation. Equally, significantly we can learn whether and how to extend the network information obtained experimentally in well‐characterized model systems to different organisms. We conclude from our analysis that, despite the recent completion of several high throughput experiments aimed at the description of complete interactomes, the available interaction information is not yet of sufficient coverage and quality to draw any biologically meaningful conclusion from the comparison of different interactomes. Thus, the transfer of network information obtained from simple organism to evolutionary distant species should be carried out and considered with caution. By using smaller higher‐confidence datasets, a larger fraction of interactions is shown to be conserved; this suggests that with the development of more accurate experimental and informatic approaches, we will soon be in the position to study the network evolution.