4D Visualization of a Nonthermal Coherent Magnon in a Laser Heated Lattice by an X-ray Free Electron Laser

Ultrafast optical manipulation of magnetic phenomena is an exciting achievement of mankind, expanding one's horizon of knowledge toward the functional nonequilibrium states. The dynamics acting on an extremely short timescale push the detection limits that reveal fascinating light-matter interactions for nonthermal creation of effective magnetic fields. While some cases are benchmarked by emergent transient behaviors, otherwise identifying the nonthermal effects remains challenging. Here, a femtosecond time-resolved resonant magnetic X-ray diffraction experiment is introduced, which uses an X-ray free-electron laser (XFEL) to distinguish between the effective field and the photoinduced thermal effect. It is observed that a multiferroic Y-type hexaferrite exhibits magnetic Bragg peak intensity oscillations manifesting entangled antiferromagnetic (AFM) and ferromagnetic (FM) Fourier components of a coherent AFM magnon. The magnon trajectory constructed in 3D space and time domains is decisive to evince ultrafast field formation preceding the lattice thermalization. A remarkable impact of photoexcitation across the electronic bandgap is directly unraveled, amplifying the photomagnetic coupling that is one of the highest among AFM dielectrics. Leveraging the above-bandgap photoexcitation, this energy-efficient optical process further suggests a novel photomagnetic control of ferroelectricity in multiferroics.

Kondo interaction in FeTe and its potential role in the magnetic order

Finding d-electron heavy fermion states has been an important topic as the diversity in d-electron materials can lead to many exotic Kondo effect-related phenomena or new states of matter such as correlation-driven topological Kondo insulator. Yet, obtaining direct spectroscopic evidence for a d-electron heavy fermion system has been elusive to date. Here, we report the observation of Kondo lattice behavior in an antiferromagnetic metal, FeTe, via angle-resolved photoemission spectroscopy, scanning tunneling spectroscopy and transport property measurements. The Kondo lattice behavior is represented by the emergence of a sharp quasiparticle and Fano-type tunneling spectra at low temperatures. The transport property measurements confirm the low-temperature Fermi liquid behavior and reveal successive coherent-incoherent crossover upon increasing temperature. We interpret the Kondo lattice behavior as a result of hybridization between localized Fe 3dxy and itinerant Te 5pz orbitals. Our observations strongly suggest unusual cooperation between Kondo lattice behavior and long-range magnetic order.

Characterization of photoinduced normal state through charge density wave in superconducting YBa2Cu3O6.67

The normal state of high-T_c cuprates has been considered one of the essential topics in high-temperature superconductivity research. However, compared to the high magnetic field study of it, understanding a photoinduced normal state remains elusive. Here, we explore a photoinduced normal state of YBa₂Cu₃O_6.67 through a charge density wave (CDW) with time-resolved resonant soft x-ray scattering, as well as a high magnetic field x-ray scattering. In the nonequilibrium state where people predict a quenched superconducting state based on the previous optical spectroscopies, we experimentally observed a similar analogy to the competition between superconductivity and CDW shown in the equilibrium state. We further observe that the broken pairing states in the superconducting CuO₂ plane via the optical pump lead to nucleation of three-dimensional CDW precursor correlation. Ultimately, these findings provide a critical clue that the characteristics of the photoinduced normal state show a solid resemblance to those under magnetic fields in equilibrium conditions.

Ribosomal protein S3 associates with the TFIIH complex and positively regulates nucleotide excision repair

In mammalian cells, the bulky DNA adducts caused by ultraviolet radiation are mainly repaired via the nucleotide excision repair (NER) pathway; some defects in this pathway lead to a genetic disorder known as xeroderma pigmentosum (XP). Ribosomal protein S3 (rpS3), a constituent of the 40S ribosomal subunit, is a multi-functional protein with various extra-ribosomal functions, including a role in the cellular stress response and DNA repair-related activities. We report that rpS3 associates with transcription factor IIH (TFIIH) via an interaction with the xeroderma pigmentosum complementation group D (XPD) protein and complements its function in the NER pathway. For optimal repair of UV-induced duplex DNA lesions, the strong helicase activity of the TFIIH complex is required for unwinding damaged DNA around the lesion. Here, we show that XP-D cells overexpressing rpS3 showed markedly increased resistance to UV radiation through XPD and rpS3 interaction. Additionally, the knockdown of rpS3 caused reduced NER efficiency in HeLa cells and the overexpression of rpS3 partially restored helicase activity of the TFIIH complex of XP-D cells in vitro. We also present data suggesting that rpS3 is involved in post-excision processing in NER, assisting TFIIH in expediting the repair process by increasing its turnover rate when DNA is damaged. We propose that rpS3 is an accessory protein of the NER pathway and its recruitment to the repair machinery augments repair efficiency upon UV damage by enhancing XPD helicase function and increasing its turnover rate.

Severe Periodontal Disease Increases Acute Myocardial Infarction and Stroke: A 10-Year Retrospective Follow-up Study

This study aimed to evaluate the causal association of periodontal disease with acute myocardial infarction (AMI) and stroke, after controlling for various confounders among the Korean population. A retrospective cohort study using the National Health Insurance Service-National Health Screening Cohort (NHIS-HEALS) was performed during 2002 to 2015 (baseline: 2002 to 2005; follow-up: 2006 to 2015) in the Republic of Korea. A total of 298,128 participants with no history of AMI or stroke were followed up for 10 y. AMI and stroke were defined by a diagnosis using the International Classification of Diseases, 10th Revision (ICD-10) guideline. Periodontal condition was classified into 3 groups (healthy, moderate periodontal disease, severe periodontal disease [SPD]) using the combination of ICD codes, treatment codes in the NHIS, and recommendation of periodontal treatment by the dentists in HEALS. Various confounders, such as sociodemographic, behavioral, systemic, and oral health factors, including hypercholesterolemia, were considered. Multivariable Cox regression analysis was applied to estimate adjusted incidence rate ratio (adjusted hazard ratio [aHR]) based on person-year of periodontal condition for AMI, stroke, and nonfatal major adverse cardiovascular events (MACEs) encompassing AMI or stroke controlling for various confounders. Stratified analyses according to age group, sex, and toothbrushing frequency were also performed. After controlling for various confounders, participants with SPD compared with non-SPD participants had a higher incidence by 11% for AMI (aHR, 1.11; 95% confidence interval [CI], 1.02-1.20), by 3.5% for stroke (aHR, 1.035; 95% CI, 1.01-1.07), and by 4.1% for MACEs (aHR, 1.04; 95% CI, 1.01-1.07). The association of SPD with AMI and MACE was highly modified in females and adults aged 40 to 59 y. In the total Korean population, SPD increased total AMI events by 4.3%, total stroke events by 1.4%, and the total MACEs by 1.6%. Our data confirmed that SPD was causally associated with the new events of AMI and stroke.

Time-resolved resonant elastic soft x-ray scattering at Pohang Accelerator Laboratory X-ray Free Electron Laser

Resonant elastic x-ray scattering has been widely employed for exploring complex electronic ordering phenomena, such as charge, spin, and orbital order, in particular, in strongly correlated electronic systems. In addition, recent developments in pump-probe x-ray scattering allow us to expand the investigation of the temporal dynamics of such orders. Here, we introduce a new time-resolved Resonant Soft X-ray Scattering (tr-RSXS) endstation developed at the Pohang Accelerator Laboratory X-ray Free Electron Laser (PAL-XFEL). This endstation has an optical laser (wavelength of 800 nm plus harmonics) as the pump source. Based on the commissioning results, the tr-RSXS at PAL-XFEL can deliver a soft x-ray probe (400 eV-1300 eV) with a time resolution of ∼100 fs without jitter correction. As an example, the temporal dynamics of a charge density wave on a high-temperature cuprate superconductor is demonstrated.

PAL-XFEL soft X-ray scientific instruments and X-ray optics: First commissioning results

We report an overview of soft X-ray scientific instruments and X-ray optics at the free electron laser (FEL) of the Pohang Accelerator Laboratory, with selected first-commissioning results. The FEL exhibited a pulse energy of 200 μJ/pulse, a pulse width of <50 fs full width at half maximum, and an energy bandwidth of 0.44% at a photon energy of 850 eV. Monochromator resolving power of 10 500 was achieved. The estimated total time resolution between optical laser and X-ray pulses was <270 fs. A resonant inelastic X-ray scattering spectrometer was set up; its commissioning results are also reported.

Charge-Spin Correlation in van der Waals Antiferromagnet NiPS_{3}

Strong charge-spin coupling is found in a layered transition-metal trichalcogenide NiPS_{3}, a van der Waals antiferromagnet, from studies of the electronic structure using several experimental and theoretical tools: spectroscopic ellipsometry, x-ray absorption, photoemission spectroscopy, and density functional calculations. NiPS_{3} displays an anomalous shift in the optical spectral weight at the magnetic ordering temperature, reflecting strong coupling between the electronic and magnetic structures. X-ray absorption, photoemission, and optical spectra support a self-doped ground state in NiPS_{3}. Our work demonstrates that layered transition-metal trichalcogenide magnets are useful candidates for the study of correlated-electron physics in two-dimensional magnetic materials.

Thread lifting: a minimally invasive surgical technique for long-standing facial paralysis

BACKGROUND

Chronic facial paralysis induces degenerative facial muscle changes on the involved side, thus, making the individual seem as older than their actual age. Furthermore, contralateral facial hypertrophy aggravates facial asymmetry. A thread-lifting procedure has been used widely for correction of a drooping or wrinkled face due to the aging process. In addition, botulinum toxin injection can be used to reduce facial hypertrophy. The aim of study was to evaluate the effectiveness of thread lifting with botulinum toxin injection for chronic facial paralysis.

METHODS

A total 34 of patients with chronic facial paralysis were enrolled from March to October 2014. Thread lifting for elevating loose facial muscles on the ipsilateral side and botulinum toxin A for controlling the facial muscle hypertrophy on the contralateral side were conducted. Facial function was evaluated using the Sunnybrook grading system and dynamic facial asymmetry ratios 1 year after treatment.

RESULTS

All 34 patients displayed improved facial symmetry and showed improvement in Sunnybrook scores (37.4 vs. 83.3) and dynamic facial asymmetry ratios (0.58 vs 0.92). Of the 34 patients, 28 (82.4%) reported being satisfied with treatment.

CONCLUSION

The application of subdermal suspension with a reabsorbable thread in conjunction with botulinum toxin A to optimize facial rejuvenation of the contralateral side constitutes an effective and safe procedure for face lifting and rejuvenation of a drooping face as a result of long-lasting facial paralysis.

Direct observation of localized spin antiferromagnetic transition in PdCrO2 by angle-resolved photoemission spectroscopy

We report the first case of the successful measurements of a localized spin antiferromagnetic transition in delafossite-type PdCrO2 by angle-resolved photoemission spectroscopy (ARPES). This demonstrates how to circumvent the shortcomings of ARPES for investigation of magnetism involved with localized spins in limited size of two-dimensional crystals or multi-layer thin films that neutron scattering can hardly study due to lack of bulk compared to surface. Also, our observations give direct evidence for the spin ordering pattern of Cr(3+) ions in PdCrO2 suggested by neutron diffraction and quantum oscillation measurements, and provide a strong constraint that has to be satisfied by a microscopic mechanism for the unconventional anomalous Hall effect recently reported in this system.

Thermoelectric imaging of structural disorder in epitaxial graphene

Heat is a familiar form of energy transported from a hot side to a colder side of an object, but not a notion associated with microscopic measurements of electronic properties. A temperature difference within a material causes charge carriers, electrons or holes to diffuse along the temperature gradient inducing a thermoelectric voltage. Here we show that local thermoelectric measurements can yield high-sensitivity imaging of structural disorder on the atomic and nanometre scales. The thermopower measurement acts to amplify the variations in the local density of states at the Fermi level, giving high differential contrast in thermoelectric signals. Using this imaging technique, we uncovered point defects in the first layer of epitaxial graphene, which generate soliton-like domain-wall line patterns separating regions of the different interlayer stacking of the second graphene layer.

Immunological impact of Taekwondo competitions

Immunological changes in elite adolescent female athletes during Taekwondo competitions were investigated on-field. 6 female athletes (16.7 ± 0.8 year-old) volunteered and performed 5 bouts of demonstration Taekwondo competitions simulating real tournaments in intensity, duration, and break-time intervals on the same day. Blood samples were taken before, after the competitions and during the recovery, respectively. Immunological changes and oxidative stress in peripheral blood mononuclear cells were evaluated by flow-cytometry. During the competitions, exercise intensity was 92.2 ± 3.8% (86.1~95.7) of the maximal heart rate. Blood lactate increased immediately after the competitions (p=0.0165) and decreased to baseline during recovery. Intracellular reactive oxygen species (ROS) in the peripheral blood increased continuously during recovery (p<0.05, respectively). Natural killer cells increased immediately after the competitions (p=0.0006), and decreased during recovery. B and T cells increased immediately after the competitions and remained elevated throughout recovery (p<0.05, respectively). CD4/CD8 ratio after the competitions was decreased (p=0.0091) and returned to baseline during recovery. These results suggest that the immunological function of the elite female adolescent athletes could be attenuated after Taekwondo competitions. Further large-scaled Taekwondo studies on immunologic and apoptotic changes related to oxidative stress should be performed for improving and protecting the health of adolescent athletes.

Anisotropic electric conductivity of delafossite PdCoO2 studied by angle-resolved photoemission spectroscopy

An explicit connection between the electronic structure and the anisotropic high conductivity of delafossite-type PdCoO2 has been established by angle-resolved photoemission spectroscopy (ARPES) and core-level x-ray photoemission spectroscopy. The ARPES spectra show that a large hexagonal electronlike Fermi surface (FS) consists of very dispersive Pd 4d states. The carrier velocity and lifetime are determined from the ARPES data, and the conductivity is calculated by a solution of the Boltzmann equation, which demonstrates that the high anisotropic conductivity originates from the high carrier velocity, the large two-dimensional FS, and the long lifetime of the carriers.

Efficacy and prognosis of a short course of prednisolone therapy for pediatric epilepsy

PURPOSE

To evaluate the efficacy and safety of adjunctive prednisolone therapy in children with cryptogenic epileptic encephalopathy, other than infantile spasms, and to determine its prognosis.

METHODS

Prednisolone, 2mg/kg per day for 6 weeks, tapered for a further 2 weeks, was given in combination with previously prescribed antiepileptic drugs. A retrospective assessment of 41 children thus treated included measurements of seizure frequency, electroencephalographic findings, global assessments of cognitive function, and adverse drug events. Long-term patient prognoses over a mean follow-up period of 3 years and 5 months (range, 14-90 months) were also examined.

RESULTS

Of 41 patients, 32 had Lennox-Gastaut syndrome, 4 had Doose syndrome, 1 had Otahara syndrome, 2 had Landau-Kleffner syndrome, and 2 had other unspecified generalized epilepsies. After prednisolone therapy, 73% (30/41) of patients showed a reduction in seizure frequency of >50%, and 59% (24/41) became seizure free. However, only seven patients (four with Lennox-Gastaut syndrome, two with Doose syndrome, and one with unspecified generalized epilepsy) who became seizure free remained free of seizures at the time of the final follow-up. Electroencephalographic findings and global assessments of cognitive function correlated well with seizure outcomes. No significant demographic factors influenced the efficacy of prednisolone or patient prognoses after prednisolone tapering. Most adverse events were transient, or were tolerated well with conservative management, with maintenance of the medication.

CONCLUSION

Prednisolone therapy may be a safe and effective adjunct in patients with cryptogenic epileptic encephalopathies, but the high relapse rate is of concern.

Vagus nerve stimulation in pediatric intractable epilepsy: a Korean bicentric study

OBJECTIVE

To present our experience with vagus nerve stimulation (VNS) and to evaluate the long-term efficacy and safety of the procedure in pediatric intractable epilepsy.

METHODS

This study included sixteen patients, who were implanted with a vagus nerve stimulator and could be followed up for at least more than 12 months in two epilepsy centers. Data including seizure frequency, EEG, quality of life measures and adverse events were prospectively filed over a 5-year period.

RESULTS

VNS resulted in a > 50% reduction in seizure frequency in 50.0% (8/16) of children with 31.3% (5/16) of patients achieving a > 90% reduction. Additionally, enhancements in quality of life were as follows: memory in 50.0% (8/16), mood in 62.5% (10/16), behavior in 68.8% (11/16), alertness in 68.8% (11/16), achievement in 37.5% (6/16), and verbal skills in 43.8% (7/16) of the patients. Adverse events included hoarseness in two patients, dyspnea during sleep in two patients, and sialorrhea in one patient. However, these events were tolerable or could be controlled by the adjustment of output currents. In one patient, wound revision was required.

CONCLUSION

Our data supports the role of VNS as an alternative therapy for pediatric intractable epilepsy.

Bond Character of Thiophene on Ge(100): Effects of Coverage and Temperature

We have studied the adsorption and decomposition of thiophene (C4H4S) on Ge(100) using scanning tunneling microscopy (STM), high-resolution core-level photoemission spectroscopy (HRPES), and density functional theory (DFT) calculation. Analysis of S 2p core-level spectra reveals three adsorption geometries, which we assign to a Ge-S dative bonding state, a [4 + 2] cycloaddition bonding state, and a decomposed bonding state (desulfurization reaction product). Furthermore, we found that the number ratio of the three adsorption geometries depended on the molecular coverage and the annealing temperature. At low coverages, the kinetically favorable dative bonding state is initially formed at room temperature. As the molecular coverage increases, thermodynamically stable [4 + 2] cycloaddition reaction products are additionally produced. In addition, we found that as the surface temperature increased, the [4 + 2] cycloaddition reaction product either possibly desorbed as molecular thiophene or decomposed to form a metallocycle-like species (C4H4Ge2) and a sulfide (Ge2S). We systematically elucidate the changes in the bonding states of adsorbed thiophene on Ge(100) according to the thiophene coverage and annealing temperature.

An orally active cathepsin K inhibitor, furan-2-carboxylic acid, 1-{1-[4-fluoro-2-(2-oxo-pyrrolidin-1-yl)-phenyl]-3-oxo-piperidin-4-ylcarbamoyl}-cyclohexyl)-amide (OST-4077), inhibits osteoclast activity in vitro and bone loss in ovariectomized rats

Human cathepsin K, a cysteine proteinase of the papain family, has been recognized as a potential drug target for the treatment of osteoporosis. The predominant expression of cathepsin K in osteoclasts has rendered the enzyme into a major target for the development of novel antiresorptive drugs. Now, we report the pharmacological properties of OST-4077 [furan-2-carboxylic acid (1-{1-[4-fluoro-2-(2-oxo-pyrrolidin-1-yl)-phenyl]-3-oxo-piperidin-4-ylcarbamoyl}-cyclohexyl)-amide] as a novel selective cathepsin K inhibitor. Human and rat cathepsin K were inhibited in vitro by OST-4077 with the IC50 values of 11 and 427 nM, respectively. OST-4077 suppressed bone resorption induced by rabbit osteoclasts (IC50, 37 nM) but did not affect bone mineralization or cellular alkaline phosphatase activity in MC3T3-E1 cells. Parathyroid hormone-induced bone resorption was inhibited in a dose-dependent manner in thyroparathyroidectomized rats gavaged with a single dose of OST-4077 (ED50, 69 mg/kg). When given orally twice daily for 4 weeks to 3-month-old ovariectomized (OVX) rats, OST-4077 dose-dependently prevented bone loss, as monitored by bone densitometry, ash content, and urinary excretion of deoxypyridinoline. No change in serum osteocalcin in the OVX rats by OST-4077 suggested that bone formation might not be affected by the agent. In summary, OST-4077 selectively inhibited bone resorbing activities of osteoclasts and prevented bone loss induced by estrogen deficiency but did not affect bone formation. OST-4077, an orally active selective human cathepsin K inhibitor, may have the therapeutic potential for the treatment of diseases characterized by excessive bone loss including osteoporosis.

Self-Induced 1-D Molecular Chain Growth of Thiophene on Ge(100)

The adsorption of thiophene on Ge(100) has been studied using scanning tunneling microscopy (STM), high-resolution core-level photoemission spectroscopy (HRPES), and density functional theory (DFT) calculations. Until now, thiophene is known to react with the Ge(100) dimer through a [4 + 2] cycloaddition reaction at room temperature, similar to the case of thiophene on Si(100). However, we found that thiophene has two adsorption geometries on Ge(100) at room temperature, such as a kinetically favorable Ge-S dative bonding configuration and a thermodynamically stable [4 + 2] cycloaddition adduct. Moreover, our STM results show that under 0.25 ML thiophene molecules preferentially produce one-dimensional molecular chain structures on Ge(100) via the Ge-S dative bonding configuration.

Exploratory activity and spatial learning in 12-month-old APP695SWE/co+PS1/ΔE9 mice with amyloid plaques

APP(695)SWE/co+PS1/DeltaE9 mice with Abeta plaques in neocortex and hippocampus were evaluated in tests of exploratory activity and spatial learning. On the initial testing day, 12-month-old APP(695)SWE/co+PS1/DeltaE9 mice spent more time than non-transgenic controls in the open arms of the elevated plus-maze. The bigenic group also travelled farther in the central region of the open-field without spending more time there. Only the bigenic group alternated above chance in the T-maze. In the Morris water maze, APP(695)SWE/co+PS1/DeltaE9 mice were impaired during acquisition of the hidden platform sub-task and the probe trial but not in the visible platform test. These results indicate a selective spatial deficit and disinhibitory tendencies in a mouse model with amyloid pathology.

Production of the neutron-rich hypernucleus 10LambdaLi in the (pi-,K+) double charge-exchange reaction

In order to produce a neutron-rich Lambda hypernucleus for the first time, we carried out an experiment by utilizing the (pi-,K+) double charge-exchange reaction on a 10B target. We observed the production of a 10LambdaLi hypernucleus. The cross section for the Lambda bound region was found to be 11.3+/-1.9 nb/sr with the 1.2 GeV/c incident momentum, which is compared with the 10LambdaB hypernucleus production cross section, 7.8+/-0.3 microb/sr, in the (pi+,K+) reaction with a 1.05 GeV/c incident momentum beam.

Exploratory activity, anxiety, and motor coordination in bigenic APPswe + PS1/ΔE9 mice

Bigenic APPswe + PS1/DeltaE9 mice with Abeta plaque formation in neocortex and hippocampus were evaluated in three tests measuring exploratory activity. By comparison to a non-transgenic group controlled for age and gender, 7-month-old APPswe + PS1/DeltaE9 mice spent more time in the open arms and had higher open/total entries and duration in the elevated plus-maze, indicative of disinhibitory tendencies. On the contrary, the groups did not differ in T-maze and open-field tests. Moreover, the motor coordination of the bigenic group was equivalent to that of controls in stationary beam, coat-hanger, rotorod, and grip strength tests. No mouse displayed neurological signs, such as pathological reflexes, myoclonus, or convulsions. The results in the elevated plus-maze test are akin to the loss of inhibitory control observed in some patients with Alzheimer's disease.

Core-level x-ray photoemission satellites in ruthenates: a new mechanism revealing the Mott transition

Core-level x-ray photoemission spectra for the Mott-Hubbard systems are calculated by the dynamical mean-field theory based on the exact diagonalization method. The spectra show a two-peak structure, screened and unscreened peaks. The screened peak is absent in a Mott insulator, but develops into the main peak when the correlation strength becomes weak and the system turns metallic. The calculated spectral behavior is consistent with the experimental Ru 3d core-level spectra of various ruthenates. This new mechanism of the core-level photoemission satellite can be utilized to reveal the Mott transition phenomenon in various strongly correlated electron systems, especially in nanoscale devices and phase-separated materials.

Localized character of 4f electrons in CeRhx (x=2,3) and CeNix (x=2,5)

We have measured Ce 4f spectral weights of extremely alpha-like Ce transition metal intermetallic compounds CeRhx (x=2,3) and CeNix (x=2,5) by using the bulk-sensitive resonant photoemission technique at the Ce M5(3d(5/2)-->4f) edge. High energy resolution and longer escape depth of photoemitted electron at this photon energy enabled us to distinguish the sharp Kondo resonance tails at the Fermi level, which can be well described by the Gunnarsson-Schönhammer calculation based on the Anderson impurity Hamiltonian. On the other hand, the itinerant 4f band description shows big discrepancies, which implies that Ce 4f electrons retain localized characters even in extremely alpha-like compounds.

Acute encephalitis associated with measles: MRI features

We document the MRI features in six patients aged 5-14 years with acute encephalitis following measles. The diagnosis was made on a characteristic morbiliform rash and detection of specific IgM and IgG antibodies. The symptoms of encephalitis occurred 1-11 days after the appearance of the rash. All patients underwent MRI within 1-4 days of the onset of neurological symptoms. Diffusion weighted images (DWI) were obtained in three patients. In all patients, T2-weighted images showed widely distributed, multifocal high signal in both cerebral hemispheres with swelling of the cortex, with bilateral, symmetrical involvement of the putamen and caudate nucleus. The lesions had showed low apparent diffusion coefficients. Three patients showed subacute gyriform haemorrhage, and asymmetrical gyriform contrast enhancement on follow-up MRI.

Bone ingrowth on a smooth-surfaced hydroxyapatite-coated acetabular cup

We studied 29 retrieved smooth-surfaced hydroxyapatite (HA)-coated acetabular cups that had been in situ for an average of 54.9 months. The outer surface of all cups carried two circular grooves dividing the smooth surface. The extent of bony in-growth and hydroxyapatite absorption was calculated using a computer imaging system (analySIS-pro 3.0, Soft Imaging System GmbH, Germany). Absorption of HA was seen in all 29 cups. The extent of absorption was, on average, 60.5%. Twenty-five cups showed bony in-growth covering an average of 13.8% of the cup surface. Thirteen cups showed bony in-growth on the smooth surface as well as the circular grooves. On 11 cups, the bony in-growth was confined to the grooves. We found that bony in-growth on the smooth-surfaced HA-coated acetabular cup was minimal. It occurred along the two circular grooves rather than on the smooth surfaces. We conclude that a macro-structure surface enhancing bony in-growth is necessary for the long-term survival of the studied cup.

Homodimers of mutant tryptophan synthase alpha-subunits in Escherichia coli

Tryptophan synthase alpha-subunit from Escherichia coli functionally exists as a heterotetramer of alpha(2)beta(2) with beta-subunit. While wild-type and mutant (F139W, T24M/F139W, and T24L/F139W) alpha-subunits were expressed as a monomer from recombinant plasmids in Escherichia coli, T24A/F139W, T24S/F139W, and T24K/F139W mutant alpha-subunits were abnormally expressed as soluble homodimers in addition to monomers. Monomers of dimer-forming mutant alpha-subunits retain high affinity to beta-subunit, high activity in stimulating catalytic activities of beta-subunit, and nearly intact content of secondary structure, indicating that the global structures of these monomers are identical to that of F139W alpha-subunit. However, fluorescence spectra of Trp139 and ANS binding indicate that significant perturbations occur in the mutant proteins. Interestingly, these defective properties of monomers caused by residue replacement were partially repaired by the dimer formation. As a result, it is suggested that dimers may be formed by domain or loop swapping, and that residue 24 may play important role in maintaining on-pathway of alpha-subunit folding.

Modulations of soleus H-reflex excitability during gait initiation: central versus peripheral influences

Soleus and tibialis anterior electromyogram (EMG) and soleus H-reflexes were recorded from the stance limb of an individual who suffered a traumatic peroneal nerve injury and of four nonimpaired individuals during gait initiation. The control subjects also initiated walking after swaying forward (sway-gait initiation), which eliminated the initial tibialis anterior activation. During the initial period of gait initiation, H-reflexes were depressed to 43% of standing values during normal-gait initiation and 86% during sway-gait initiation in the nonimpaired subjects. H-reflexes of the nerve-injured subject were depressed to 37%, even though no tibialis anterior EMG was observed. The findings support the view that reciprocal inhibition of the soleus during a task, which normally involves tibialis anterior activation, is due to a centrally mediated process.

Investigation of juxtasellar and cerebellopontine angle meningiomas and neurogenic tumours: two-phase helical CT

We performed two-phase helical CT in 31 patients with juxtasellar region and cerebellopontine angle tumours to evaluate its usefulness in differentiating meningiomas from neurogenic tumours. After the intravenous injection of 90 ml contrast medium at 3 ml/s, axial helical images were obtained with delays of 30 and 120 s. After the delayed axial images, we acquired coronal images. Changes in attenuation were assessed visually and quantitatively (by comparing the attenuation in Hounsfield units). There were 17 meningiomas and 14 neurogenic tumours, all pathologically proven. Two-phase helical CT showed a decrease in attenuation in 15 (88%) meningiomas and an increase in 14 (100%) neurogenic tumours from early to delayed axial images. Coronal images showed a decrease in attenuation in all 17 meningiomas and an increase in 13 (93%) of the neurogenic tumours. The mean HU and their ratios were significantly different between meningiomas and neurogenic tumours.

Tripartite structure of Saccharomyces cerevisiae Dna2 helicase/endonuclease

In order to gain insights into the structural basis of the multifunctional Dna2 enzyme involved in Okazaki fragment processing, we performed biochemical, biophysical and genetic studies to dissect the domain structure of Dna2. Proteolytic digestion of Dna2 using subtilisin produced a 127 kDa polypeptide that lacked the 45 kDa N-terminal region of Dna2. Further digestion generated two subtilisin-resistant core fragments of approximately equal size, 58 and 60 kDa. Surprisingly, digestion resulted in a significant (3- to 8-fold) increase in both ATPase and endonuclease activities compared to the intact enzyme. However, cells with a mutant DNA2 allele lacking the corresponding N-terminal region were severely impaired in growth, being unable to grow at 37 degrees C, indicating that the N-terminal region contains a domain critical for a cellular function(s) of Dna2. Analyses of the hydrodynamic properties of and in vivo complex formation by wild-type and/or mutant Dna2 lacking the N-terminal 45 kDa domain revealed that Dna2 is active as the monomer and thus the defect in the mutant Dna2 protein is not due to its inability to multimerize. In addition, we found that the N-terminal 45 kDa domain interacts physically with a central region located between the two catalytic domains. Our results suggest that the N-terminal 45 kDa domain of Dna2 plays a critical role in regulation of the enzymatic activities of Dna2 by serving as a site for intra- and intermolecular interactions essential for optimal function of Dna2 in Okazaki fragment processing. The possible mode of regulation of Dna2 is discussed based upon our recent finding that replication protein A interacts functionally and physically with Dna2 during Okazaki fragment processing.

Characterization of antidepressant-like effects of p-synephrine stereoisomers

We previously reported that p-synephrine has antidepressant-like activity in the murine models of forced swimming and tail suspension. In the present study, we characterized antidepressant-like effects of p-synephrine stereoisomers in both in vivo and in vitro systems. In the tail suspension test, S-(+)-p-synephrine (3 mg/kg, p.o.) reduced the duration of immobility, while R-(-)-p-synephrine (0.3-3 mg/kg, p.o.) had no effect. S-(+)-p-synephrine (0.3, 1 and 3 mg/kg, p.o.) and R-(-)-p-synephrine (1 mg/ kg and 3 mg/kg, p.o.) significantly reversed the reserpine (2.5 mg/kg, i.p.)-induced hypothermia. S-(+)-p-synephrine was more effective than R-(-)-p-synephrine in inhibition of both [3H]noradrenaline uptake in rat cerebral cortical slices (maximal inhibition 85.7 +/- 7.8% vs. 59.8 +/- 4.3%; EC50 5.8 +/- 0.7 microM vs. 13.5 +/- 1.2 microM) and [3H]nisoxetine binding (Ki 4.5 +/- 0.5 microM vs. 8.2 +/- 0.7 microM). In contrast, R-(-)-p-synephrine was more effective than S-(+)-p-synephrine in stimulation of [3H]noradrenaline release from rat cerebral cortical slices (maximal stimulation 23.9 +/- 1.8% vs. 20.1 +/- 1.7%; EC50 8.2 +/- 0.6 microM vs. EC50 12.3 +/- 0.9 microM). The stimulatory effect of R-(-)-p-synephrine on [3H]noradrenaline release was inhibited by nisoxetine (100 nM), but tetrodotoxin (1 microM) and elimination of extracellular calcium had no effect. It is suggested that S-(+)-p-synephrine has more effective antidepressant-like activity than R-(-)-p-synephrine.

Extracellular signal-regulated kinase/90-KDA ribosomal S6 kinase/nuclear factor-kappa B pathway mediates phorbol 12-myristate 13-acetate-induced megakaryocytic differentiation of K562 cells

Two signaling pathways, the extracellular signal-regulated kinase (ERK)/mitogen-activated protein kinase (MAPK)-dependent pathway and the nuclear factor-kappaB (NF-kappaB)-dependent pathway, have been known to mediate megakaryocytic differentiation of K562 cells induced by phorbol 12-myristate 13-acetate (PMA). In this study, we examined whether 90-kDa ribosomal S6 kinase (RSK), known as a substrate of ERK/MAPK and a signal-inducible IkappaBalpha kinase, would link two pathways during the differentiation. RSK1 was activated in a time- and dose-dependent manner during the PMA-induced differentiation. Overexpression of wild-type or dominant inhibitory mutant (D205N) of RSK1 enhanced or suppressed PMA-stimulated NF-kappaB activation and megakaryocytic differentiation as shown by morphology, nonspecific esterase activity, and expression of the CD41 megakaryocytic marker, respectively. In addition, overexpression of the dominant inhibitory mutant (S32A/S36A) of IkappaBalpha inhibited PMA-stimulated and RSK1-enhanced megakaryocytic differentiation, indicating that NF-kappaB mediates a signal for megakaryocytic differentiation downstream of RSK1. PMA-stimulated activation of ERK/MAPK, RSK1, and NF-kappaB and the PMA-induced megakaryocytic differentiation were prevented by pretreatment with PD98059, a specific inhibitor of the mitogen-activated ERK kinase (MEK). Therefore, these results demonstrate that the sequential ERK/RSK1/NF-kappaB pathway mediates PMA-stimulated megakaryocytic differentiation of K562 cells.

A co-operative study: clinical characteristics of 334 Korean patients with moyamoya disease treated at neurosurgical institutes (1976-1994). The Korean Society for Cerebrovascular Disease

A co-operative study was conducted to determine the clinical characteristics of patients with moyamoya disease who were diagnosed and treated at neurosurgical institutes in Korea before 1995. Twenty-six hospitals contributed 505 cases and among them, the clinical characteristics of 334 patients with definite moyamoya disease were evaluated. The number of patients began to increase from the late 1980s, and after that approximately 20 patients were treated each year. There were two age peaks: from six to 15 and from 31 to 40 years of age. Haemorrhagic manifestations occurred in approximately 43% of the patients. The major clinical manifestations were haemorrhage in adults (62.4%) and ischaemia in children (61.2%). Overall 54.5% of the patients experienced decreased consciousness levels, mainly due to intracranial haemorrhage or cerebral infarction. In the patients with ischemic manifestations, the adult patients were more likely to have cerebral infarction than the pediatric patients (80% vs. 39%) and the pediatric patients were more likely to have TIA (61% vs. 25%). Thirty eight percent of the patients underwent bypass surgery and 53% of these procedures were performed bilaterally. Treatment policies, including indications for bypass surgery and commonly used drugs, were somewhat different according to the institution. Overall favorable outcome was 73%, and the most significant factor affecting poor outcome was haemorrhagic manifestation. This article describes the characteristics of 334 patients with moyamoya disease, who were diagnosed and treated at neurosurgical institutes in Korea before 1995.

Novel nucleosides with vinyl fluoride or vinyl bromide moiety as open-chain analogs of neplanocin A

Novel nucleosides with vinyl fluoride and vinyl bromide were designed, synthesized and evaluated their antiviral activities against poliovirus, HSV, HIV, and HBV.

Lateralizing ability of single-voxel proton mr spectroscopy in hippocampal sclerosis: comparison with mr imaging and positron emission tomography

BACKGROUND AND PURPOSE

Proton MR spectroscopy (MRS) is still in the early stages in the evaluation of epilepsy, and comparisons with MR imaging and positron emission tomography (PET) in the same patients have rarely been documented. The purpose of this study was to evaluate the lateralizing ability of single-voxel MRS in comparison with MR imaging and PET in patients with hippocampal sclerosis.

METHODS

Thirty-three patients with intractable temporal lobe epilepsy whose MR imaging diagnosis was unilateral hippocampal sclerosis and who underwent anterior temporal lobectomy and had good postsurgical outcome over 1-year follow-up were included in the study. MR spectra were obtained from the hippocampus bilaterally, using the point-resolved spectroscopy sequence. Metabolite ratios of NAA/Cho and NAA/Cr were calculated from the relative peak height measurements. An NAA/Cho ratio of 0.8 or less and an NAA/Cr ratio of 1.0 or less were regarded as abnormal. The MRS results were compared retrospectively with those of MR imaging and PET as to the ability to lateralize the epileptogenic focus.

RESULTS

The sensitivity of MRS and PET (concordance with MR imaging) was 85% each in the lateralization of the ipsilateral lesion side. Bilateral abnormalities were seen in 30% of the patients. False-lateralization rates for MRS and PET were 3% and 6%, respectively. The concordance rate of MRS and PET was 73%, when comparing the results of the ipsilateral lesion side.

CONCLUSION

MRS may be used as an adjunct tool in the evaluation of hippocampal sclerosis, like PET, although its sensitivity has to be improved and the clinical significance of bilateral abnormality is still to be determined.

Structure-activity relationships of apio nucleosides as potential antiviral agents

Several types of novel apio nucleosides were synthesized starting from 1,3-dihydroxyacetone and evaluated for antiviral activity. Among compounds tested, amino substituted apio dideoxynucleosides exhibited anti-HBV activity, while thioapio dideoxynucleosides were found to be active against HIV-1. Apio dideoxydidehydro nucleosides showed moderate to potent anti-HCMV activity, but their bioisosteric thioapio dideoxydidehydro nucleosides did not exhibit any significant antiviral activity.

Synthesis of novel D- and L-3'-deoxy-3'-C-hydroxymethyl nucleoside with exocyclic methylene as potential ribonucleotide reductase inhibitor

D- and L-3'-Deoxy-3'-C-hydroxymethyl thymidine substituted with exocyclic methylene at 2'-position were synthesized, starting from D- and L-xylose as potential ribonucleotide reductase inhibitor, respectively, but they were found to be inactive against several tumor cell lines.

Synthesis of novel 3'-deoxy-3'-C-hydroxymethyl nucleosides with conformationally rigid sugar moiety as potential antiviral agents

Based on the fact that the ring expanded 3'-C-hydroxymethyl analogue of oxetanocin A exhibited potent antiviral activity, two types of conformationally rigid 3'-C-hydroxymethyl derivatives in which 2'-hydroxyl group is linked to the 4'-position or to the 6'-position were synthesized starting from 1,2;5,6-di-O-isopropylidene-D-glucose, respectively.

Design and synthesis of novel fluorocyclopropanoid nucleosides

Novel fluorocyclopropanoid nucleosides were designed, synthesized and evaluated their antiviral activities against poliovirus, HSV, HIV, and HBV.

Synthesis and antiviral activity of D- and L-2'-azido-2',3'-dideoxy-4'-thiopyrimidine and purine nucleosides

Novel D- and L-2'-azido-2',3'-dideoxy-4'-thionucleosides were synthesized starting from L- and D-xylose via D- and L-4-thioarabitol derivative as key intermediates and evaluated for antiviral activity, respectively. When the final nucleosides were tested against HIV-1, HSV-1, HSV-2, and HCMV, they were found to be only active against HCMV without cytotoxicity up to 100 micrograms/ml.

Activation of heat shock factor 1 by pyrrolidine dithiocarbamate is mediated by its activities as pro-oxidant and thiol modulator

Pyrrolidine dithiocarbamate (PDTC) is known to inhibit NF-kappa B, which plays a critical role(s) as an immediate early mediator of immune and inflammatory responses. Here we show that PDTC induces heat shock factor 1 (HSF1) activation and heat shock protein expression, while other antioxidants such as butylated hydroxytoluene (BHT), n-propylgallate (PG), ascorbic acid (AA), and N-acetyl-L-cysteine (NAC) do not. Since PDTC exerts other functions than antioxidant, e.g., a pro-oxidant, metal chelator, and thiol group modulator, we examined which of these activities is responsible for the PDTC-induced HSF1 activation. PDTC-induced HSF1 activation was not prevented by metal chelators, EDTAs, indicating that the metal chelating effect of PDTC is not linked to the HSF1 activation. PDTC increased intracellular GSSG level. In addition, PDTC-induced activation of HSF1 was significantly inhibited by NAC and a thiol-reducing agent dithiothreitol (DTT), while it was partially prevented by other antioxidants, AA, BHT, and PG. These results suggest that the activation of HSF1 by PDTC may be due to its activities as pro-oxidant and thiol group modulator rather than anti-oxidant.

Implication of a small GTPase Rac1 in the activation of c-Jun N-terminal kinase and heat shock factor in response to heat shock

Heat shock induces c-Jun N-terminal kinase (JNK) activation as well as heat shock protein (HSP) expression through activation of the heat shock factor (HSF), but its signal pathway is not clearly understood. Since a small GTPase Rac1 has been suggested to participate in the cellular response to stresses, we examined whether Rac1 is involved in the heat shock response. Here we show that moderate heat shock (39-41 degrees C) induces membrane translocation of Rac1 and membrane ruffling in a Rac1-dependent manner. In addition, Rac1N17, a dominant negative mutant of Rac1, significantly inhibited JNK activation by heat shock. Since Rac1V12 was able to activate JNK, it is suggested that heat shock may activate JNK via Rac1. Similar inhibition by Rac1N17 of HSF activation in response to heat shock was observed. However, inhibitory effects of Rac1N17 on heat shock-induced JNK and HSF activation were reduced as the heat shock temperature increased. Rac1N17 also inhibited HSF activation by l-azetidine-2-carboxylic acid, a proline analog, and heavy metals (CdCl)), suggesting that Rac1 may be linked to HSF activation by denaturation of polypeptides in response to various proteotoxic stresses. However, Rac1N17 did not prevent phosphorylation of HSF1 in response to these proteotoxic stresses. Interestingly, a constitutively active mutant Rac1V12 did not activate the HSF. Therefore, Rac1 activation may be necessary, but not sufficient, for heat shock-inducible HSF activation and HSP expression, or otherwise a signal pathway(s) involving Rac1 may be indirectly involved in the HSF activation. In sum, we suggest that Rac1 may play a critical role(s) in several aspects of the heat shock response.

Anti-inflammatory effect of the aqueous extract from Lonicera japonica flower is related to inhibition of NF-kappaB activation through reducing I-kappaBalpha degradation in rat liver

We investigated the anti-inflammatory effects of aqueous extract from Lonicera japonica flower (AELJ), a traditional skin rash drug, in lipopolysaccharide (LPS)-induced rat liver sepsis. Immunoblot analysis showed that the level of nuclear factor (NF)-kappaBp65 was rapidly up-regulated and inhibitory (I)-kappaBalpha was down-regulated by LPS challenge. However, AELJ inhibited the increase of NF-kappaBp65 and degradation of I-kappaBalpha in the liver of LPS-challenged rats. Immunohistochemical analysis of rat hepatocytes showed that LPS-induced inflammatory responses, involving degradation of I-kappaBalpha and induction of NF-kappaBp65, tumor necrosis factor (TNF)-alpha and inducible nitric oxide synthase (iNOS), are partially inhibited by pretreatment with AELJ. These results suggest that AELJ may act as a therapeutic agent for inflammatory disease through a selective regulation of NF-kappaB activation.