Parametric attosecond pulse amplification far from the ionization threshold from high order harmonic generation in He.

Parametric amplification of attosecond coherent pulses around 100 eV at the single-atom level is demonstrated for the first time by using the 3D time-dependent Schrödinger equation in high-harmonic generation processes from excited states of He+. We present the attosecond dynamics of the amplification process far from the ionization threshold and resolve the physics behind it. The amplification of a particular central photon energy requires the seed XUV pulses to be perfectly synchronized in time with the driving laser field for stimulated recombination to the He+ ground state and is only produced in a few specific laser cycles in agreement with the experimental measurements. Our simulations show that the amplified photon energy region can be controlled by varying the peak intensity of the laser field. Our results pave the way to the realization of compact attosecond pulse intense XUV lasers with broad applications.

Discharge characteristics of steady-state high-density plasma source based on cascade arc discharge with hollow cathode.

We developed a steady-state high-density plasma source by applying a hollow cathode to a cascade arc discharge device. The hollow cathode is made of a thermionic material (LaB6) to facilitate plasma production inside it. The cascade arc discharge device with the hollow cathode produced a stationary plasma with an electron density of about 1016 cm-3. It was found that the plasma source produces a strong pressure gradient between the gas feed and the vacuum chamber. The plasma source separated the atmospheric pressure (100 kPa) and a vacuum (100 Pa) when the discharge was performed with an argon gas flow rate of 5.0 l/min and a discharge current of 40 A. An analysis of the pressure gradient along the plasma source showed that the pressure difference between the gas feed and the vacuum chamber can be well described by the Hagen-Poiseuille flow equation, indicating that the viscosity of the neutral gas is the dominant factor for producing this pressure gradient. A potential profile analysis suggested that the plasma was mainly heated within cylindrical channels whose inner diameter was 3 mm. This feature and the results of the pressure ratio analysis indicated that the temperature, and, thus, viscosity, of the neutral gas increased with the increasing number of intermediate electrodes. The discharge characteristics and shape of the hollow cathode are suitable for plasma window applications.

Characteristics of plasma window with various channel diameters for accelerator applications.

Plasma window is a feasible device as an atmosphere-vacuum interface, which can withstand energetic particle beams. It is, however, essential to enlarge the diameter to several tens of millimeters for actual beam passing in the accelerator applications. The pressure separation performance and discharge voltage V current I characteristics should be investigated in detail to design the plasma window for each purpose. Therefore, a cascade arc discharge device with a diameter of up to 20 mm was developed, and its characteristics as a function of diameter were examined. As a result, with an increase in the channel diameter, the discharge pressure that was achieved decreased, whose values were smaller compared with the values by the prediction formula, assuming the viscous gas flow with a constant plasma temperature. It showed that the bulk plasma temperature for the larger discharge channel was low because of the low-current density over the channel. Furthermore, the transition of the V-I slope was observed with an increase in the diameter.

Intensity and polarization of laser-induced fluorescence due to forbidden excitation of He atoms immersed in an electric field in plasmas.

Laser-induced fluorescence (LIF) processes through the Stark and electric-quadrupole moment (QDP) transitions of HeI (2(1)S-->n1D-->2(1)P,n=3,4) have been investigated for reliable electric-field measurements in plasmas. A linear-polarization model is formulated for various configurations of electric fields, magnetic fields, and laser polarization. To extend the model to higher-particle-density plasmas we develop a rate-equation model involving a collisional disalignment term. Disalignment rates of n1D states, Rda, due to a collision with He gas were measured. Spatial distributions in intensity and polarization of LIF were observed in a discharge plasma. For n=3 with small Rda, the same electric-field distribution in the sheath was obtained from either of the intensity ratios of the Stark to QDP component and the polarization, and the sheath potential agreed well with that by an electric probe. For n=4 with large Rda, the distribution was also correctly obtained from partially depolarized LIF wave forms by using the extended model. These results show that our extended model provides an accurate measurement of the electric field. The minimum detectable field strength was 80 V/cm for n=4. Application and limitations of the methods are discussed.

Cloning and characterization of the antigenic membrane protein (Amp) gene and in situ detection of Amp from malformed flowers infected with Japanese hydrangea phyllody phytoplasma.

A Japanese hydrangea phyllody (JHP) disease found throughout Japan causes economic damage to the horticultural industry. JHP phytoplasma-infected Japanese hydrangea plants show several disease symptoms involved in floral malformations, such as virescence, phyllody and proliferation. Here, we cloned and characterized the antigenic membrane protein (Amp) gene homolog from the JHP phytoplasma (JHP-amp), expressed the JHP-Amp protein in Escherichia coli cells, and then obtained an antibody against JHP-Amp. The antibody against JHP-Amp had no cross-reactions with the antibody against the Amp protein from a closely related onion yellows phytoplasma. This serologic specificity is probably due to the high diversity of the hydrophilic domains in the Amp proteins. The in situ detection of the JHP-Amp protein revealed that the JHP phytoplasma was localized to the phloem tissues in the malformed flower. This study shows that the JHP-Amp protein is indeed a membrane protein, which is expressed at detectable level in the JHP phytoplasma-infected hydrangea.

Enhancement of double auger decay probability in xenon clusters irradiated with a soft-x-ray laser pulse.

The interaction of large Xe clusters with a soft x-ray laser pulse having a wavelength of 13.9 nm and an intensity of up to 2x10(10) W/cm2 was investigated using a time-of-flight ion mass spectrometer. The corresponding laser photon energy was sufficiently high to photoionize Xe 4d innershell electrons. It was found that Xe3+ ions (which result from double Auger decay of 4d vacancies) became the dominant final ionic product with increasing cluster size and x-ray intensity. This is in contrast to the results of synchrotron radiation experiments involving free Xe atoms, in which Xe2+ is the dominant resultant ion species. Possible mechanisms responsible for the enhancement of the double Auger transition probability in x-ray laser and cluster interaction are discussed.

Development of a cascade arc discharge source for an atmosphere-vacuum interface device.

To realize a novel vacuum-atmosphere interface that does not require a large differential pumping system, a robust cascade arc discharge source called a plasma window is constructed and tested for long-term operation. By modifying a test plasma with a direct current discharge, a vacuum interface with a high gas pressure ratio of 1/407 between the discharge and expansion sections is demonstrated for currents as high as 20 A. No significant damage to the electrodes is observed during the operation. Analysis of the visible emission spectra reveals that a stationary, stable argon plasma having a temperature of 1 eV and a density of 1.5 × 10(16) cm(-3) is generated in the plasma channel.

A plasmid isolated from phytopathogenic onion yellows phytoplasma and its heterogeneity in the pathogenic phytoplasma mutant.

A 3.6-kbp DNA fragment was cloned from the extrachromosomal DNA of a pathogenic plant mollicute, onion yellows phytoplasma (OY-W). Sequence analysis of the fragment revealed an open reading frame (ORF) encoding the replication (Rep) protein of rolling-circle replication (RCR)-type plasmids. This result suggests the existence of a plasmid (pOYW1) in OY-W that uses the RCR mechanism. This assumption was confirmed by detecting the single-stranded DNA (ssDNA) of a replication intermediate that is specifically produced by the RCR mechanism. This is the first report on the identification of the replication system of this plasmid and the genes encoded in it. With a DNA fragment including the Rep gene region of pOYW1 used as a probe, Southern and Northern (RNA) blot hybridizations were employed to examine the heterogeneity between the plasmids found in OY-W and a pathogenic mutant (OY-M) isolated from OY-W. Multiple bands were detected in the DNA and RNA extracted from both OY-W and OY-M infected plants, although the banding patterns were different. Moreover, the copy number of plasmids from OY-W was about 4.2 times greater than that from OY-M. These results indicate constructive heterogeneity between OY-W and OY-M plasmids, and the possibility of a relationship between the plasmid-encoded genes and the pathogenicity of the phytoplasma was suggested.

Cloning and expression analysis of Phytoplasma protein translocation genes.

Genes encoding SecA and SecY proteins, essential components of the Sec protein translocation system, were cloned from onion yellows phytoplasma, an unculturable plant pathogenic bacterium. The secA gene consists of 2,505 nucleotides encoding an 835 amino acid protein (95.7 kDa) and shows the highest similarity with SecA of Bacillus subtilis. Anti-SecA rabbit antibody was prepared from a purified partial SecA protein, with a histidine tag expressed in Escherichia coli. Western blot analysis confirmed that SecA protein (approximately 96 kDa) is produced in phytoplasma-infected plants. Immunohistochemical thin sections observed by optical microscopy showed that SecA is characteristically present in plant phloem tissues infected with phytoplasma. The secY gene consists of 1,239 nucleotides encoding a 413 amino acid protein (45.9 kDa) and shows the highest similarity with SecY of B. subtilis. These results suggest the presence of a functional Sec system in phytoplasmas. Because phytoplasmas are endocellular bacteria lacking cell walls, this system might secrete bacterial proteins directly into the host cytoplasm. This study is what we believe to be the first report of the sequence and expression analysis of phytoplasma genes encoding membrane proteins with a predicted function.

Postischemic enhancements of N-methyl-D-aspartic acid (NMDA) and non-NMDA receptor-mediated responses in hippocampal CA1 pyramidal neurons.

Glutamate receptor-mediated responses were investigated by using a whole-cell recording and an intracellular calcium ion ([Ca2+]i) imaging in gerbil postischemic hippocampal slices prepared at 1, 3, 6, 9, 12, and 24 hours after 5-minute ischemia. Bath application of N-methyl-D-aspartic acid (NMDA), alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA), and kainate showed that NMDA-, AMPA- and kainate-induced currents were enhanced in postischemic CA1 pyramidal neurons at 1 to 12 hours after 5-minute ischemia. NMDA and non-NMDA receptor-mediated excitatory postsynaptic currents (EPSC) were examined in postischemic CA1 pyramidal neurons at 3 hours after 5-minute ischemia to confirm whether synaptic responses are enhanced in the postischemic CA1 pyramidal neurons. The amplitudes of NMDA- and non-NMDA-receptor-mediated EPSC were enhanced in the postischemic CA1 pyramidal neurons. NMDA-, AMPA-, and kainate-induced [Ca2+]i elevations were also examined to determine whether the enhancement of currents is accompanied by the enhancement of [Ca2+]i elevation. The enhancements of NMDA-, AMPA-, and kainate-induced [Ca2+]i elevations were shown in the postischemic CA1. These results indicate that NMDA and non-NMDA receptor-mediated responses are persistently enhanced in the CA1 pyramidal neurons 1 to 12 hours after transient ischemia, and suggest that the enhancement of glutamate receptor-mediated responses may act as one of crucial factors in the pathologic mechanism responsible for leading postischemic CA1 pyramidal neurons to irreversible neuronal injury.

Expression of the gene encoding the coat protein of cucumber mosaic virus (CMV) strain WL appears to provide protection to tobacco plants against infection by several different CMV strains.

The gene (cp) encoding the coat protein (CP) of cucumber mosaic virus (CMV) strain WL (CMV-WL, which belongs to CMV subgroup II) was custom polymerase chain reaction (CPCR)-engineered for expression as described by Slightom [Gene 100 (1991) 251-255]. CPCR amplification was used to add 5'- and 3'-flanking NcoI sites to the CMV-WL cp gene, and cp was cloned into the expression vector, pUC18cpexp. This CMV-WL cp expression cassette was transferred into the genome of tobacco (Nicotiana tabacum cv. Havana 423) via the Agrobacterium T-DNA transfer mechanism. R0 plants that express the CMV-WL cp gene were subcloned, propagated, and challenge-inoculated with CMV-WL. Several R0 plant lines showed excellent protection against CMV-WL infection; however, plants found to accumulate the highest CP levels did not show the highest degree of protection. Thus in our case, CP levels appear not to be a useful predictor of the degree of protection. Plants from the best protected CMV-WL cp gene-expressing R0 tobacco lines were also inoculated with CMV strains belonging to the other major CMV subgroup (subgroup I), CMV-C and CMV-Chi, and compared in a parallel experiment with a transgenic tobacco plant line that expresses the CMV-C cp gene. Plants expressing the CMV-WL cp gene appeared to show a broader spectrum of protection against infection by the various CMV strains than plants expressing the CMV-C cp gene.

Random mutagenesis in a plant viral genome using a DNA repair-deficient mutator Escherichia coli strain.

Random mutagenesis in a plant viral genome is valuable for generating attenuated strains or for analyzing viral gene function at the molecular level. A DNA repair-deficient mutator Escherichia coli strain was used for random mutagenesis of a plant viral genome. A full-length infectious cDNA clone of Citrus tatter leaf virus (genus Capillovirus) L strain (CTLV-L) genomic RNA under the T7 promoter sequence (pITCL) was introduced into the mutator E. coli strain XL1-Red and mutagenized overnight. To fix mutations, the mixture of plasmid DNA isolated from colonies of the mutator bacteria was introduced into another E. coli strain, JM109, which has normal DNA repair function. Infectious viral genomic RNA was transcribed in vitro from each mutagenized pITCL clone and inoculated on host plants. Phenotypic mutants were selected for altered pathogenicity in the inoculated plants. Nucleotide sequence analysis of each mutant revealed that mutations were introduced randomly into the CTLV-L genome regardless of the function of the viral gene. The nucleotide substitutions were biased towards single point mutations, which consisted of more transitions than transversions or single-base frameshifts. These mutations were preserved stably in plants subject to sequential mechanical inoculation. The strategy presented below is a simple and very efficient way to generate virus mutants for analyzing the functions of viral genes.

Functional changes of N-methyl-D-aspartic acid and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate channels in gerbil hippocampal CA1, in relation to postischemic enhancement of glutamate receptor-mediated responses.

Glutamate receptor-mediated responses have been reported to be enhanced in the postischemic CA1 pyramidal neurons before the appearance of delayed neuronal death, and the enhancement has been thought to be one of crucial factors leading postischemic CA1 pyramidal neurons to irreversible neuronal injury. In the present study, we examined what changes in functional properties of N-methyl-D-aspartic acid (NMDA) and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) channels are responsible for the enhanced postischemic glutamate receptor-mediated responses. Gerbils were subjected to 5-min ischemia to induce the enhancement of glutamate receptor-mediated responses and the hippocampal slices were prepared 3 h after ischemia. Single channel activities evoked by NMDA and AMPA were recorded from outside-out patches excised from the postischemic CA1 pyramidal neurons. The main conductance levels of NMDA and AMPA channels in the postischemic CA1 pyramidal neurons were not significantly different from those in control CA1 pyramidal neurons. The mean open time and the open-state probability of NMDA and AMPA channels significantly increased in the postischemic CA1 pyramidal neurons (NMDA channels: mean open time, 1.4-fold increase; open-state probability, 1.5-fold increase) (AMPA channels: mean open time, 1.3-fold increase; open-state probability, 1.8-fold increase). These findings indicate that the increases in the mean open time and the open-state probability of NMDA and AMPA channels are responsible for the enhancement of postischemic NMDA and non-NMDA receptor-mediated responses.

The integrity of the disulfide bond in a cyclic somatostatin analog during 99mTc complexation reactions.

Recent development of a variety of thiol-free chelating agents has facilitated the design of 99mTc-labeled somatostatin analogs suitable for receptor imaging of somatostatin-positive tumors. However, it remains ambiguous whether the disulfide bonds in cyclic peptides are stable during 99mTc complexation reactions, and contradictory results have been reported regarding the integrity of disulfide bonds in cyclic somatostatin analogs. To estimate the stability of the disulfide bond in a synthetic somatostatin analog at low peptide concentrations, [125I]I-RC-160, in which radioiodine was incorporated into the 3-Tyr residue, was synthesized and the integrity of the disulfide bond of the peptide was investigated in the presence of reducing agents such as ascorbic acid, dithionite, and stannous ions. The disulfide bond in [125I]I-RC-160 remained stable in the presence of ascorbic acid in boiling water. The disulfide bond was also stable when treated with stannous ions at concentrations sufficient to reduce 99mTc for complexation with a thiol-free chelating agent, bis(hydroxamamide) analog when the 99mTc complexation reaction was performed at room temperature. However, the disulfide bond of [125I]I-RC-160 was slightly cleaved in the presence of a small amount of stannous ions when the reaction was performed in boiling water. Treatment of [125I]I-RC-160 with dithionite in boiling water markedly reduced the disulfide bond of the parental peptide. These findings indicated that synthetic somatostatin analogs may be labeled with 99mTc with stannous ions as the reducing agent without impairing their structure after conjugation of thiol-free chelating agents that provide 99mTc chelates under mild reaction conditions.

Plasma protein binding of (99m)Tc-labeled hydrazino nicotinamide derivatized polypeptides and peptides.

6-Hydrazinopyridine-3-carboxylic acid (HYNIC) constitutes one of the most attractive reagents to prepare (99m)Tc-labeled polypeptides and peptides of various molecular weights in combination with two tricine molecules as coligands. Indeed, (99m)Tc-HYNIC-conjugated IgG showed biodistribution of radioactivity similar to that of (111)In-DTPA-conjugated IgG. However, recent studies indicated significant plasma protein binding when the (99m)Tc labeling procedure was expanded to low molecular weight peptides. In this study, pharmacokinetics of (99m)Tc-HYNIC-conjugated IgG, Fab and RC160 using tricine were compared with their radioiodinated counterparts to evaluate this (99m)Tc-labeling method. In mice, [(99m)Tc](HYNIC-IgG)(tricine)(2) and [(99m)Tc](HYNIC-Fab)(tricine)(2) showed persistent localization of radioactivity in tissues when compared with their (125)I-labeled counterparts. [(99m)Tc](HYNIC-IgG)(tricine)(2) eliminated from the blood at a rate similar to that of (125)I-labeled IgG, while [(99m)Tc](HYNIC-Fab)(tricine)(2) showed significantly slower clearance of the radioactivity than (125)I-labeled Fab. On size-exclusion HPLC analyses, little changes were observed in radiochromatograms after incubation of [(99m)Tc](HYNIC-IgG)(tricine)(2) in murine plasma. However, [(99m)Tc](HYNIC-Fab)(tricine)(2) and [(99m)Tc](HYNIC-RC160)(tricine)(2) demonstrated significant increases in the radioactivity in higher molecular weight fractions in plasma. Formation of higher molecular weight species was reduced when [(99m)Tc](HYNIC-RC160)(tricine)(2) was stabilized with nicotinic acid (NIC) to generate [(99m)Tc](HYNIC-RC160)(tricine)(NIC). [(99m)Tc](HYNIC-RC160)(tricine)(NIC) also demonstrated significantly faster clearance of the radioactivity from the blood than [(99m)Tc](HYNIC-RC160)(tricine)(2). These findings suggested that one of the tricine coligands in (99m)Tc-HYNIC-labeled (poly)peptides would be replaced with plasma proteins to generate higher molecular weight species that exhibit slow blood clearance. In addition, the molecular sizes of parental peptides played an important role in the progression of the exchange reaction of one of the tricine coligands with plasma proteins.

Sensory and motor responses to deep brain stimulation. Correlation with anatomical structures.

Motor and sensory responses induced by trial stimulation were examined before stereotaxically implanting a permanent stimulating electrode for pain relief in 11 patients with intractable pain of central origin. The total number of points eliciting a response when stimulated was 70. The points of stimulation were determined as exactly as possible from Schaltenbrand and Bailey's Atlas. Motor responses were detected upon stimulating 21 points, the majority of which were in the posterior third of the posterior limb of the internal capsule (IC). Stimulation of these 21 points was accompanied by pain relief in only two points (10%). Warm (22) or cool sensations (three) were provoked in the most posteromedial portion of the posterior limb of the IC, nucleus reticularis pulvinaris, and area triangularis, and seven (28%) of these 25 sensations were accompanied by pain relief. A burning sensation was found upon stimulation of 12 points, with stimulation in the mesencephalic lateral tegmental field eliciting the most severe burning pain. A tingling sensation was elicited at 12 points, in a distribution similar to that of the warm sensation. Five (42%) of these 12 points provided pain relief. The best stimulating point for pain relief is not in the center of the posterior limb of the IC, directly lateral to the posterior commissure, but rather in its most posteromedial part; that is, at the nucleus reticularis pulvinaris or area triangularis.

Synthesis of 15 alpha-hydroxyestrogen 15-N-acetylglucosaminides.

The synthesis of 15-N-acetylglucosaminides of 15 alpha-hydroxyesterone, 15 alpha-hydroxyestradiol, and 15 alpha-hydroxyestriol (estetrol) is described. The latter two were prepared by condensation of 2-acetamido-1 alpha-chloro-1,2-dideoxy-3,4,6-trio-O-acetyl-D-glucopyranose with appropriately protected 15 alpha-hydroxyestrogens by the Koenigs-Knorr reaction employing cadmium carbonate as a catalyst. Subsequent removal of protecting groups with methanolic potassium hydroxide provided the desired conjugates. 15 alpha-Hydroxyestrone 15-N-acetylglucosaminide was synthesized from the corresponding 15 alpha-hydroxyestradiol derivative by Jones oxidation followed by brief alkaline hydrolysis. These conjugates underwent enzymatic hydrolysis with beta-N-acetylglucosaminidase from Jack beans to produce 15 alpha-hydroxyestrogens.

Isolation and Characterization of Derivative Lines of the Onion Yellows Phytoplasma that Do Not Cause Stunting or Phloem Hyperplasia.

ABSTRACT Two lines of onion yellows phytoplasma producing milder symptoms were isolated from the original line (OY-W). One has an additional characteristic, non-insect-transmissibility (OY-NIM), compared with the other (OY-M). OY-M was established after maintaining OY-W for 11 years on a plant host (Chrysanthemum coronarium) with an insect vector (Macrosteles striifrons), and OY-NIM was isolated after subsequent maintenance of OY-M in plants by periodic grafting. Polymerase chain analysis suggested that OY-NIM cannot traverse the gut or survive in the hemolymph of the leafhopper. OY-W results in witches'-broom formation and stunted growth in the host plant. In contrast, OY-M and OY-NIM do not cause stunting in the host plant, although they result in witches'-broom. Histopathological analysis of these lines revealed that the hyperplastic phloem tissue and severe phloem necrosis seen in OY-W did not exist in OY-M and OY-NIM. This was attributed to a reduction in the population of phytoplasma in tissues in both OY-M- and OY-NIM-infected plants. The results suggest that the cause of stunting and phloem hyperplasia may be genetically different from the cause of witches'-broom. Pulsed field gel electrophoresis analysis showed that OY-M had a smaller genome size ( approximately 870 kbp) than OY-W ( approximately 1,000 kbp). Thus, some of the OY-W genes responsible for pathogenicity may not be present in OY-M.

Diencephalic syndrome of emaciation (Russell's syndrome). Long-term survival.

Three cases of diencephalic syndrome are reported. Two of them, which have been observed postoperatively for more than 7 years, showed typical clinical and endocrinologic features at the time of their first admission, but showed mass signs uncharacteristic of diencephalic syndrome after recurrence of the tumor. Recent data showed a normal baseline for plasma growth hormone but abnormalities in provocation tests. The significance of age in the manifestation of the syndrome is briefly discussed, especially in relation to the tendency toward normalization in the growth hormone level at a later age.

Reappraisal of endorectal pull-through procedure. II. Animal experiment.

Anorectal manometry and pelvic histology following endorectal pull-through and simple abdominoperineal pull-through procedures were studied experimentally in dogs. dogs that had undergone endorectal pull-through preserved normal resting pressure of the anal canal, rectoanal reflex response, and intact perirectal anatomy. Dogs that had simple abdominoperineal pull-through, on the other hand, showed low anal canal pressure, loss of rectoanal reflex, and damage of the pelvic muscles. good continence following endorectal pull-through operation was supported by these physiologic and anatomic studies.