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Various cationic polymers are used to deliver polyplex-mediated antisense oligonucleotides (ASOs). However, few studies have investigated the structural determinants of polyplex functionalities in polymers. This study focused on the polymer hydrophobicity. A series of amphiphilic polyaspartamide derivatives possessing various hydrophobic (R) moieties together with cationic diethylenetriamine (DET) moieties in the side chain (PAsp(DET/R)s) were synthesized to optimize the R moieties (or hydrophobicity) for locked nucleic acid (LNA) gapmer ASO delivery. The gene knockdown efficiencies of PAsp(DET/R) polyplexes were plotted against a hydrophobicity parameter, logD7.3, of PAsp(DET/R), revealing that the gene knockdown efficiency was substantially improved by PAsp(DET/R) with logD7.3higher than -2.4. This was explained by the increased polyplex stability and improved cellular uptake of ASO payloads. After intratracheal administration, the polyplex samples with a higher logD7.3than -2.4 induced a significantly higher gene knockdown in the lung tissue compared with counterparts with lower hydrophobicity and naked ASO. These results demonstrate that the hydrophobicity of PAsp(DET/R) is crucial for efficient ASO delivery in vitroand in vivo.

Antisense oligonucleotide (ASO) is a major tool used for silencing pathogenic genes. For stroke in the hyperacute stage, however, the ability of ASO to regulate genes is limited by its poor delivery to the ischemic brain owing to sudden occlusion of the supplying artery. Here we show that, in a mouse model of permanent ischemic stroke, lipid-ligand conjugated DNA/RNA heteroduplex oligonucleotide (lipid-HDO) was unexpectedly delivered 9.6 times more efficiently to the ischemic area of the brain than to the contralateral non-ischemic brain and achieved robust gene knockdown and change of stroke phenotype, despite a 90% decrease in cerebral blood flow in the 3 h after occlusion. This delivery to neurons was mediated via receptor-mediated transcytosis by lipoprotein receptors in brain endothelial cells, the expression of which was significantly upregulated after ischemia. This study provides proof-of-concept that lipid-HDO is a promising gene-silencing technology for stroke treatment in the hyperacute stage.

We recently reported the antisense properties of a DNA/RNA heteroduplex oligonucleotide consisting of a phosphorothioate DNA-gapmer antisense oligonucleotide (ASO) strand and its complementary phosphodiester RNA/phosphorothioate 2′-O-methyl RNA strand. When α-tocopherol was conjugated with the complementary strand, the heteroduplex oligonucleotide silenced the target RNA more efficiently in vivothan did the parent single-stranded ASO. In this study, we designed a new type of the heteroduplex oligonucleotide, in which the RNA portion of the complementary strand was replaced with phosphodiester DNA, yielding an ASO/DNA double-stranded structure. The ASO/DNA heteroduplex oligonucleotide showed similar activity and liver accumulation as did the original ASO/RNA design. Structure-activity relationship studies of the complementary DNA showed that optimal increases in the potency and the accumulation were seen when the flanks of the phosphodiester DNA complement were protected using 2′-O-methyl RNA and phosphorothioate modifications. Furthermore, evaluation of the degradation kinetics of the complementary strands revealed that the DNA-complementary strand as well as the RNA strand were completely cleaved in vivo. Our results expand the repertoire of chemical modifications that can be used with the heteroduplex oligonucleotide technology, providing greater design flexibility for future therapeutic applications.

For the simultaneous delivery of antisense oligonucleotides and their effector enzymes into cells, nanosized vesicular polyion complexes (PICs) were fabricated from oppositely charged polyion pairs of oligonucleotides and poly(ethylene glycol) (PEG)-b-polypeptides. First, the polyion component structures were carefully designed to facilitate a multimolecular (or secondary) association of unit PICs for noncovalent (or chemical cross-linking-free) stabilization of vesicular PICs. Chemically modified, single-stranded oligonucleotides (SSOs) dramatically stabilized the multimolecular associates under physiological conditions, compared to control SSOs without chemical modifications and duplex oligonucleotides. In addition, a high degree of guanidino groups in the polypeptide segment was also crucial for the high stability of multimolecular associates. Dynamic light scattering and transmission electron microscopy revealed the stabilized multimolecular associates to have a 100 nm sized vesicular architecture with a narrow size distribution. The loading number of SSOs per nanovesicle was determined to be ∼2500 using fluorescence correlation spectroscopic analyses with fluorescently labeled SSOs. Furthermore, the nanovesicle stably encapsulated ribonuclease H (RNase H) as an effector enzyme at ∼10 per nanovesicle through simple vortex-mixing with preformed nanovesicles. Ultimately, the RNase H-encapsulated nanovesicle efficiently delivered SSOs with RNase H into cultured cancer cells, thereby eliciting the significantly higher gene knockdown compared with empty nanovesicles (without RNase H) or a mixture of nanovesicles with RNase H without encapsulation. These results demonstrate the great potential of noncovalently stabilized nanovesicles for the codelivery of two varying bio-macromolecule payloads for ensuring their cooperative biological activity.

Duchenne muscular dystrophy (DMD) is caused by mutations in DMD, which codes for dystrophin. Because the progressive and irreversible degeneration of muscle occurs from childhood, earlier therapy is required to prevent dystrophic progression. Exon skipping by antisense oligonucleotides called phosphorodiamidate morpholino oligomers (PMOs), which restores the DMDreading frame and dystrophin expression, is a promising candidate for use in neonatal patients, yet the potential remains unclear. Here, we investigate the systemic efficacy and safety of earlyexon skipping in dystrophic dog neonates. Intravenous treatment of canine X-linked muscular dystrophy in Japan dogs with a 4-PMO cocktail resulted in ∼3%–27% in-frame exon 6–9 skipping and dystrophin restoration across skeletal muscles up to 14% of healthy levels. Histopathology was ameliorated with the reduction of fibrosis and/or necrosis area and centrally nucleated fibers, significantly in the diaphragm. Treatment induced cardiac multi-exon skipping, though dystrophin rescue was not detected. Functionally, treatment led to significant improvement in the standing test. Toxicity was not observed from blood tests. This is the first study to demonstrate successful multi-exon skipping treatment and significant functional improvement in dystrophic dogs. Early treatment was most beneficial for respiratory muscles, with implications for addressing pulmonary malfunction in patients.

Duchenne muscular dystrophy is a lethal X-linked muscle disorder. We have already reported that osteopontin (OPN), an inflammatory cytokine and myogenic factor, is expressed in the early dystrophic phase in canine X-linked muscular dystrophy in Japan, a dystrophic dog model. To further explore the possibility of OPN as a new biomarker for disease activity in Duchenne muscular dystrophy, we monitored serum OPN levels in dystrophic and wild-type dogs at different ages and compared the levels to other serum markers, such as serum creatine kinase, matrix metalloproteinase-9, and tissue inhibitor of metalloproteinase-1. Serum OPN levels in the dystrophic dogs were significantly elevated compared with those in wild-type dogs before and 1 hour after a cesarean section birth and at the age of 3 months. The serum OPN level was significantly correlated with the phenotypic severity of dystrophic dogs at the period corresponding to the onset of muscle weakness, whereas other serum markers including creatine kinase were not. Immunohistologically, OPN was up-regulated in infiltrating macrophages and developmental myosin heavy chain–positive regenerating muscle fibers in the dystrophic dogs, whereas serum OPN was highly elevated. OPN expression was also observed during the synergic muscle regeneration process induced by cardiotoxin injection. In conclusion, OPN is a promising biomarker for muscle regeneration in dystrophic dogs and can be applicable to boys with Duchenne muscular dystrophy.

X-ray and near-infrared ( $J$– $H$– $K_{\rm s}$) observations of the galactic black-hole binary GX 339 $-$4 in the low/hard state were performed with Suzaku and IRSF in 2009 March. The spectrum in the 0.5–300 keV band is dominated by thermal Comptonization of multicolor disk photons, with a small contribution from a direct disk component, indicating that the inner disk is almost fully covered by hot corona with an electron temperature of $\approx$175 keV. The Comptonizing corona has at least two optical depths, $\tau$$\approx$1, 0.4. Analysis of the iron-K line profile yields an inner-disk radius of (13.3 $^{+6.4}_{-6.0}$) $\ R_{\rm g}$( $\ R_{\rm g}$represents the gravitational radius $GM/c^2$), with the best-fit inclination angle of $\approx$50 $^\circ$. This radius is consistent with that estimated from the continuum fit by assuming the conservation of photon numbers in Comptonization. Our results suggest that the standard disk of GX 339 $-$4 is likely truncated before reaching the innermost stable circular orbit (for a non-rotating black hole) in the low/hard states at $\sim\ $1% of the Eddington luminosity. The one-day averaged near-infrared light curves are found to be correlated with hard X-ray flux with $F_{\rm Ks}$$\propto$$F_{\rm X}^{0.45}$. The flatter near-infrared $\nu F_{\nu}$spectrum than the radio one suggests that the optically thin synchrotron radiation from the compact jets dominates the near-infrared flux. Based on a simple analysis, we estimate the magnetic field and size of the jet base to be 5 $\times$10 $^{4}\ $G and 6 $\times$10 $^{8}\ $cm, respectively. The synchrotron self Compton component is estimated to be approximately 0.4% of the total X-ray flux.

We made deep near-infrared (JHKs) imaging polarimetry toward the Serpens cloud core, which is a nearby, active cluster forming region. The polarization vector maps show that the near-infrared reflection light in this region mainly originates from SVS 2 and SVS 20, and enable us to detect 24 small infrared reflection nebulae associated with young stellar objects. Polarization measurements of near-infrared point sources indicate an hourglass-shaped magnetic field, of which the symmetry axis is nearly perpendicular to the elongation of the C18O (J = 1-0) or submillimeter continuum emission. The bright part of C18O (J = 1-0), submillimeter continuum cores as well as many Class 0/I objects are located just toward the constriction region of the hourglass-shaped magnetic field. Applying the Chandrasekhar and Fermi method and taking into account the recent study on the signal integration effect for the dispersion component of the magnetic field, the magnetic field strength was estimated to be [?]100 mG, suggesting that the ambient region of the Serpens cloud core is moderately magnetically supercritical. This suggests that the Serpens cloud core first contracted along the magnetic field as an elongated cloud, which is perpendicular to the magnetic field, and that the central part then contracted across the magnetic field due to the high density in the central region of the cloud core, where star formation is actively continuing. Comparison of this magnetic field with previous observations of molecular gas and large-scale outflows suggests a possibility that the cloud dynamics are controlled by the magnetic field, protostellar outflows, and gravitational inflows. Furthermore, the outflow energy injection rate appears to be larger than the dissipation rate of the turbulent energy in this cloud, indicating that the outflows are the main source of turbulence and that the magnetic field plays an important role both in allowing the outflow energy to escape from the central region of the cloud core and enabling the gravitational inflows from the ambient region to the central region. These characteristics appear to be in good agreement with the outflow-driven turbulence model and imply the importance of the magnetic field to continuous star formation in the center region of the cluster forming region.

The HH 1-2 region in the L1641 molecular cloud was observed in the near-infrared (IR) J, H, and Ks bands, and imaging polarimetry was performed. Seventy-six point-like sources were detected in all three bands. The near-IR polarizations of these sources seem to be caused mostly by the dichroic extinction. Using a color-color diagram, reddened sources with little IR excess were selected to trace the magnetic field structure of the molecular cloud. The mean polarization position angle of these sources is about 111deg, which is interpreted as the projected direction of the magnetic field in the observed region of the cloud. The distribution of the polarization angle has a dispersion of about 11deg, which is smaller than what was measured in previous studies. This small dispersion gives a rough estimate of the strength of the magnetic field to be about 130 mG and suggests that the global magnetic field in this region is quite regular and straight. In contrast, the outflows driven by young stellar objects in this region seem to have no preferred orientation. This discrepancy suggests that the magnetic field in the L1641 molecular cloud does not dictate the orientation of the protostars forming inside.

We have determined interstellar extinction law toward the Galactic center (GC) at the wavelength from 1.2 to 8.0 mm, using point sources detected in the IRSF/SIRIUS near-infrared (NIR) survey and those in the Two Micron All Sky Survey (2MASS) and Spitzer/IRAC/GLIMPSE II catalogs. The central region [?]l [?] [?]3.deg0 and [?]b [?] [?]1.deg0 has been surveyed in the J, H, and KS bands with the IRSF telescope and the SIRIUS camera whose filters are similar to the Mauna Kea Observatories (MKO) NIR photometric system. Combined with the GLIMPSE II point source catalog, we made KS versus KS - l color-magnitude diagrams (CMDs) where l=3.6, 4.5, 5.8, and 8.0 mm. The KS magnitudes of bulge red clump stars and the KS - l colors of red giant branches are used as a tracer of the reddening vector in the CMDs. From these magnitudes and colors, we have obtained the ratios of total-to-selective extinction $A_{K_S}/E_{K_S-\lambda }$ for the four IRAC bands. Combined with $A_{\lambda }/A_{K_S}$ for the J and H bands derived by Nishiyama et al., we obtain AJ :AH :$A_{K_S}$:A [3.6]:A [4.5]:A [5.8]:A [8.0] = 3.02:1.73:1:0.50:0.39:0.36:0.43 for the line of sight toward the GC. This confirms the flattening of the extinction curve at l [?] 3 mm from a simple extrapolation of the power-law extinction at shorter wavelengths, in accordance with recent studies. The extinction law in the 2MASS J, H, and KS bands has also been calculated, and good agreement with that in the MKO system is found. Thus, it is established that the extinction in the wavelength range of J, H, and KS is well fitted by a power law of steep decrease A l [?] l-2.0 toward the GC. In nearby molecular clouds and diffuse interstellar medium, the lack of reliable measurements of the total-to-selective extinction ratios hampers unambiguous determination of the extinction law; however, observational results toward these lines of sight cannot be reconciled with a single extinction law.

In a $J$, $H$, and $K_{\rm S}$band survey of the Galactic center region over an area of 2${}^\circ$$\times$5${}^\circ$, we have found many dark clouds, among which a distinguished chain of dark clouds can be identified with a quiescent CO cloud. The distances of the clouds are estimated to be 3.2–4.2 kpc, corresponding to the Norma arm, by our new method for determining the distances to dark clouds using the cumulative number of stars against the $J-K_{\rm S}$color. By adopting these estimated distances, the size and total mass of the cloud are estimated to be $\sim$70 pc in length and 6 $\times$10$^4$$M_\odot$, respectively. Three compact HII regions exist in the cloud, indicating that star-forming activities are going on at the cores of the quiescent CO cloud on the spiral arm.

Microglial activation followed by recruitment of blood-borne macrophages into the central nervous system (CNS) aggravates neuroinflammation. Specifically, in multiple sclerosis (MS) as well as in experimental autoimmune encephalomyelitis (EAE), a rodent model of MS, activated microglia and macrophages (Mg/Mφ) promote proinflammatory responses and expand demyelination in the CNS. However, a potent therapeutic approach through the systemic route for regulating their functions has not yet been developed. Here, we demonstrated that a systemically injected DNA/RNA heteroduplex oligonucleotide (HDO), composed of an antisense oligonucleotide (ASO) and its complementary RNA, conjugated to cholesterol (Chol-HDO) distributed more efficiently to demyelinating lesions of the spinal cord in EAE mice with significant gene silencing than the parent ASO. Importantly, systemic administration of Cd40-targeting Chol-HDO improved clinical signs of EAE with significant downregulation of Cd40in Mg/Mφ. Furthermore, we successfully identified that macrophage scavenger receptor 1 (MSR1) is responsible for the uptake of Chol-HDO by Mg/Mφ of EAE mice. Overall, our findings demonstrate the therapeutic potency of systemically administered Chol-HDO to regulate activated Mg/Mφ in neuroinflammation.

We present a polarimetric map of a 20' x 20' area toward the Galactic center. The polarization of point sources has been measured in the J, H, and KS bands using the near-infrared polarimetric camera SIRPOL on the 1.4 m telescope IRSF. One percent or better accuracy of polarization degree is achieved for sources with J < 14.5, H < 13.5, and KS < 12.0. Comparing the Stokes parameters between high extinction stars and relatively low extinction ones, we have obtained a polarization originating from magnetically aligned dust grains at the central region of our Galaxy of at most 1-2 kpc. The distribution of the position angles shows a peak at [?]20deg, nearly parallel to the Galactic plane, suggesting a toroidal magnetic configuration. The derived direction of the magnetic field is in good agreement with that obtained from far-infrared/submillimeter observations, which detect polarized thermal emission from dust in the molecular clouds at the Galactic center. Our results show that, by subtracting foreground components, near-infrared polarimetry allows investigation of the magnetic field structure at the Galactic center.

Infrared absorption lines of H+3, including the metastable R(3,3)l line, have been observed toward eight bright infrared sources associated with hot and massive stars located in and between the Galactic center cluster and the Quintuplet cluster 30 pc to the east. The absorption lines with high-velocity dispersion arise in the Galaxy's central molecular zone (CMZ) as well as in foreground spiral arms. The temperature and density of the gas in the CMZ, as determined from the relative strengths of the H3+ lines, are T = 200-300 K and n [?] 50-200 cm[?]3. The detection of high column densities of H3+ toward all eight stars implies that this warm and diffuse gaseous environment is widespread in the CMZ. The products of the ionization rate and path length for these sight lines are 1000 and 10 times higher than in dense and diffuse clouds in the Galactic disk, respectively, indicating that the ionization rate, z, is not less than 10[?]15 s[?]1 and that L is at least on the order of 50 pc. The warm and diffuse gas is an important component of the CMZ, in addition to the three previously known gaseous environments: (1) cold molecular clouds observed by radio emission of CO and other molecules; (2) hot ( T = 104-106 K) and highly ionized diffuse gas ( ne = 10-100 cm[?]3) seen in radio recombination lines, far infrared atomic lines, and radio-wave scattering; and (3) ultrahot ( T = 107-108 K) X-ray emitting plasma. Its prevalence significantly changes the understanding of the environment of the CMZ. The sight line toward GC IRS 3 is unique in showing an additional H3+ absorption component, which is interpreted as being due to either a cloud associated with circumnuclear disk or the "50 km s[?]1 cloud" known from radio observations. An infrared pumping scheme is examined as a mechanism to populate the (3,3) metastable level in this cloud.

We have determined the ratios of total to selective extinction directly from observations in the optical V band and near-infrared J band toward the Galactic center. The OGLE (Optical Gravitational Lensing Experiment) Galactic bulge fields have been observed with the SIRIUS camera on the Infrared Survey Facility telescope, and we obtain AV/EV-J = 1.251 +- 0.014 and AJ/EV-J = 0.225 +- 0.007. From these ratios, we derive AJ/AV = 0.188 +- 0.005; combining this with the near-infrared extinction ratios obtained in Paper I for more reddened fields near the Galactic center, we obtain AV:AJ:AH:A Ks = 1:0.188:0.108:0.062, which implies steeply declining extinction toward longer wavelengths. In particular, it is striking that the Ks-band extinction is [?]1/16 the visual extinction AV, much smaller than the 1/10 usually employed.

We present the results of a Suzaku study of a bright point-like source in the 6.7keV intensity map of the Galactic center region. We detected an intense FeXXV 6.7keV line with an equivalent width of $\sim$1keV as well as emission lines of highly ionized Ar and Ca from a spectrum obtained by the X-ray Imaging Spectrometer. The overall spectrum is described very well by a heavily absorbed ($\sim$2$\times$10$^{23}$cm$^{-2}$) thin thermal plasma model with a temperature of 3.8$\pm$0.6keV and a luminosity of $\sim$3$\times$10$^{34}$ergs$^{-1}$(2.0-8.0keV) at 8kpc. The absorption, temperature, luminosity, and the 6.7keV line intensity were confirmed with the archived XMM-Newton data. The source has a very red ($J-K_{\rm s}=$8.2mag) infrared spectral energy distribution (SED), which was fitted by a blackbody emission of $\sim$1000K attenuated by a visual extinction of $\sim$31mag. The high plasma temperature and the large X-ray luminosity are consistent with a wind-wind colliding Wolf-Rayet binary. The similarity of the SED to those of the eponymous Quintuplet cluster members suggests that the source is a WC-type source.

We present a near-infrared ($JHK_{\rm s}$) photometric catalog, including 14811185 point sources for a 40 deg$^2$area of the Large Magellanic Cloud, 2769682 sources for an 11 deg$^2$area of the Small Magellanic Cloud, and 434145 sources for a 4 deg$^2$area of the Magellanic Bridge. The 10$\sigma$limiting magnitudes are 18.8, 17.8, and 16.6 mag at $J, H$, and $K_{\rm s}$, respectively. The photometric and astrometric accuracies for bright sources are 0.03–0.04 mag and 0$\rlap {.}{^{\prime\prime}}$1, respectively. Based on the catalog, we also present (1) spatial distributions, (2) luminosity functions, (3) color–color diagrams, and (4) color–magnitude diagrams for point sources toward the Magellanic Clouds.

We conducted deep JHK$_{\rm s}$imaging polarimetry of a $\sim$8$' \times$8$'$area of the NGC 2071 star-forming region. Our polarization data revealed various infrared reflection nebulae (IRNe) associated with the central IR young star cluster NGC 2071IR and identified their illuminating sources. There are at least 4 IRNe in NGC 2071IR, and several additional IRNe were identified around nearby young stars in the same field-of-view. Each illuminating source coincides with a known near-IR source, except for IRS 3, which is only a part of IRN 2 and is illuminated by the radio source 1c. Aperture polarimetry of each cluster source was used to detect unresolved circumstellar disk/outflow systems. Aperture polarimetry of the other point-like sources within the field was conducted in this region for the first time. The magnetic field structures (from $\sim$1 pc down to $\sim$0.1 pc) were derived using both aperture polarimetry of the point-like sources and imaging polarimetry of the shocked H$_2$emission that is seen as the dominant knotty nebulae in the $K_{\rm s}$band image; both are of dichroic origin and the derived field directions are consistent with each other. The magnetic field direction projected on the sky is also consistent with that inferred from the 850$\mu$m thermal continuum emission polarimetry of the central 0.2 pc region, but is running roughly perpendicular ($\sim$75$^{\circ}$) to the direction of the large-scale outflow. We argue that the field strength is too weak to align the outflow in the large-scale field direction via magnetic braking.

We conducted wide-field $JHK_{\rm s}$imaging polarimetry toward NGC 2024, which is a massive star-forming region in the Orion B cloud. We found a prominent and extended polarized nebula over NGC 2024, and constrained the location of the illuminating source of the nebula through an analysis of polarization vectors. A massive star, IRS 2b with a spectral type of O8-B2, is located in the center of the symmetric vector pattern. Five small polarized nebulae associated with YSOs were discovered on our polarization images. These nebulae are responsible for the structures of circumstellar matter (i.e., disk/envelope systems) that produce strongly polarized light through dust scattering. For the point-like sources, we performed software aperture polarimetry in order to measure integrated polarizations, with which we detected candidate sources associated with circumstellar material. We found five young brown dwarfs with highly polarized integrated emission. These sources serve as direct evidence for the existence of a disk/envelope system around brown dwarfs. We investigated the fraction of highly polarized sources against the intrinsic luminosity of stars ($\propto$mass), and found that the source detection rate remains constant from low luminosity (brown dwarfs) to higher luminosity (solar-type) stars. This result indicates that the relative disk scale-hight is rather independent of the stellar mass. We investigated the magnetic field structure of NGC 2024 through measurements of dichroic polarization. The average position angle of projected magnetic fields across the region is found to be 110${}^{\circ}$. We found a good consistency in magnetic field structures obtained using near-infrared dichroic polarization and sub-mm/far-infrared dust emission polarization, indicating that the dichroic polarizations at near-infrared wavelengths trace magnetic field structures inside dense ($A_{V} \lesssim 50$mag) molecular clouds.

We present the polarization images in the $J, H$, and $K_{\rm s}$bands of the Orion Molecular Cloud 1 South region. The polarization images clearly show at least six infrared reflection nebulae (IRNe) which are barely seen or invisible in the intensity images. Our polarization vector images also identify the illuminating sources of the nebulae; IRN 1 and 2, IRN 3, 4, and 5, and IRN 6 are illuminated by three IR sources, Source 144–351, Source 145–356, and Source 136–355, respectively. Moreover, our polarization images suggest the candidate driving sources of the optical Herbig-Haro objects for the first time; HH 529, a pair of HH 202 and HH 528 or HH 203/204, and HH 530 and HH 269 are originated from Source 144–351, Source 145–356, and Source 136–355, respectively.

We have carried out the first near-infrared (NIR) polarimetric imaging observations of the central part (7$\rlap{.}^{\prime}$7 $\times$7$\rlap{.}^{\prime}$7 $\sim 110 {\rm\; pc} \times 110 {\rm\; pc}$) of 30 Doradus. The totals of 106, 131, and 34 sources have significant polarization degrees at $J, H$, and $K_{\rm s}$, respectively. The $E$-vectors toward 30 Dor were mapped with unprecedentedly high resolutions. As previously noticed by optical observations, there is an overall tendency for the $E$-vectors to be roughly aligned in the east-west direction. In addition, our observations reveal a more complex structure of their alignment. The position angles of the $E$-vectors are not uniform, but show a gradual spatial variation. It is plausible to assume that they trace the magnetic field toward 30 Dor. One of the expanding shells toward 30 Dor, Shell 5, is clearly enveloped by $E$-vectors. The expanding shell has probably swept the magnetic field together into the rim, while creating the curved structure. We obtained the ratios of polarization degree among the NIR wavelengths: $P_H / P_J = 0.76\pm0.02$and $P_{K_{\rm s}} / P_H = 0.87\pm0.06$. These fit a power-law dependence of $P \propto \lambda^{-0.9}$.

Recent studies have indicated the significance of zinc in neurodegeneration after transient global ischemia. After ischemia, excess glutamate and zinc, which are released in the synaptic clefts, cause the apoptotic death of the target neurons, and finally lead the pathogenesis of vascular type of dementia. Considering the removal of zinc using zinc-sensitive chelators was effective in the prevention of neuronal death after transient global ischemia, it is highly possible that substances which protect against zinc-induced neuronal death will become a candidate for drugs of vascular type of dementia. Based on this ‘zinc hypothesis’, we have searched for such substances among various agricultural products including fruits, vegetables, and fishes using our developed in vitro screening system. Among tested, we found that carnosine (-alanyl histidine) protected against zinc-induced death of cultured neurons, and have applied for the patent as a drug of ischemia-induced neuronal death and the treatment/prevention for vascular type of dementia (application No. 2006-145857) in Japan. Here, we review the perspective of protective substances of zinc-induced neuronal death as a drug of vascular type of dementia based on our studies and other numerous studies.

We have conducted J, H, and Ks imaging observations of the Coalsack Globule 2 with the SIRIUS infrared camera on the IRSF 1.4 m telescope at SAAO and determined the color excess ratio, EJ-H/EH [?] Ks. The ratio is determined in the same photometric system as our previous study of the r Oph and Cha clouds without any color transformation; this enables us to directly compare the near-infrared extinction laws among these regions. The current ratio, EJ-H/EH [?] Ks = 1.91 +- 0.01 for the extinction range 0.5 < EJ-H < 1.8, is significantly larger than the ratios for the r Oph and Cha clouds (EJ-H/EH [?] Ks = 1.60-1.69). This ratio corresponds to a large negative index a = 2.34 +- 0.01 when the wavelength dependence of extinction is approximated by a power law Al [?] l-a, which in this cloud might indicate little growth of dust grains, larger abundance of dielectric nonabsorbing components, such as silicates, or both. We also confirm that the color excess ratio for the Coalsack Globule 2 has a trend of increasing with decreasing optical depth, which is the same trend as for the r Oph and Cha clouds.

We have found Herbig Ae/Be star candidates in the western region of the Magellanic Bridge. Using the near-infrared camera SIRIUS and the 1.4 m telescope IRSF, we surveyed ~3.0deg x 1.3deg (24deg [?] a [?] 36deg, -75.0deg [?] d [?] -73.7deg) in the J, H, and Ks bands. On the basis of colors and magnitudes, about 200 Herbig Ae/Be star candidates are selected. Considering the contaminations by miscellaneous sources, such as foreground stars and early-type dwarfs in the Magellanic Bridge, we estimate that about 80 ([?]40%) of the candidates are likely to be Herbig Ae/Be stars. We also found one concentration of the candidates at the young star cluster NGC 796, strongly suggesting the existence of pre-main-sequence (PMS) stars in the Magellanic Bridge. This is the first detection of PMS star candidates in the Magellanic Bridge, and if they are genuine PMS stars, this could be direct evidence of recent star formation. However, the estimate of the number of Herbig Ae/Be stars depends on the fraction of classical Be stars, and thus a more precise determination of the Be star fraction or observations to differentiate between the Herbig Ae/Be stars and classical Be stars are required.

On the basis of the near-infrared observations of bulge red clump stars near the Galactic center, we have determined the galactocentric distance to be R0 = 7.52 +- 0.10 (stat) +-0.35 (sys) kpc. We observed the red clump stars at [?] l [?] [?] 1.deg0 and 0.deg7 [?] [?] b [?] [?] 1.deg0 with the IRSF 1.4 m telescope and the SIRIUS camera in the H and KS bands. After extinction and population corrections, we obtained (m - M)0 = 14.38 +- 0.03 (stat) +- 0.10 (sys). The statistical error is dominated by the uncertainty of the intrinsic local red clump stars' luminosity. The systematic error is estimated to be +-0.10, including uncertainties in extinction and population correction, zero point of photometry, and the fitting of the luminosity function of the red clump stars. Our result, R0 = 7.52 kpc, is in excellent agreement with the distance determined geometrically with the star orbiting the massive black hole in the Galactic center. The recent result based on the spatial distribution of globular clusters is also consistent with our result. In addition, our study exhibits that the distance determination to the Galactic center with the red clump stars, even if the error of the population correction is taken into account, can achieve an uncertainty of about 5%, which is almost the same level as that in recent geometrical determinations.

We determine and compare the color excess ratios EJ-H/Eimg1.gif for the r Ophiuchi and Chamaeleon dark clouds with the J-, H-, and Ks-band simultaneous camera, SIRIUS, on the IRSF 1.4 m telescope at SAAO. Determining accurate ratios is indispensable for discussions of the extinction law. However, previous surveys suffered from uncertainties in transforming one photometric system to another when comparing data on different systems. To overcome the problem, we observe both clouds in exactly the same photometric system on the same telescope, greatly simplifying the comparison of the extinction laws between two clouds. From our surveys covering about 1.56 deg2 (r Oph) and 2.77 deg2 (Chamaeleon), which are complete for J ~ 19.0, H ~ 18.3, and KS ~ 17.0 mag at a 10 s limiting magnitude, we did not find a significant difference in the extinction law EJ-H/Eimg1.gif for the two clouds, in contrast to previous work. From calculations of a model star with the effects of filter and atmosphere transmissions, the differences of the color excess ratios EJ-H/EH-K for two clouds described in the past literature can be attributed to the different photometric systems so far employed. We also note a change of the color excess ratio that occurs with increasing optical depth.

We have determined the ratios of total to selective extinction in the near-infrared bands (J,H,Ks) toward the Galactic center from the observations of the region [?] l [?] [?] 2.deg0 and 0.deg5 [?] [?] b [?] [?] 1.deg0 with the IRSF telescope and the SIRIUS camera. Using the positions of red clump stars in color-magnitude diagrams as a tracer of the extinction and reddening, we determine the average of the ratios of total to selective extinction to be Aimg1.gif/Eimg2.gif = 1.44 +- 0.01, Aimg1.gif/Eimg3.gif = 0.494 +- 0.006, and AH/EJ-H = 1.42 +- 0.02, which are significantly smaller than those obtained in previous studies. From these ratios, we estimate that AJ : AH : Aimg1.gif = 1 : 0.573 +- 0.009 : 0.331 +- 0.004 and EJ-H/Eimg2.gif = 1.72 +- 0.04, and we find that the power law Al [?] l-1.99+-0.02 is a good approximation over these wavelengths. Moreover, we find a small variation in Aimg1.gif/Eimg2.gif across our survey. This suggests that the infrared extinction law changes from one line of sight to another, and the so-called universality does not necessarily hold in the infrared wavelengths.

We present the design, construction, and performance of TRISPEC (Triple Range Imager and Spectrograph), a simultaneous optical and near-infrared imager, spectrograph, and polarimeter. This instrument splits the incoming light from a telescope into the three beams-one optical channel (0.45-0.90 ?m) and two infrared channels (0.90-1.85 and 1.85-2.5 ?m)-by means of two dichroic mirrors. It is capable of simultaneous three-band imaging or spectroscopy, with or without polarimetry. Low-resolution grisms (R?70-360) cover a wide wavelength range of 0.46-2.5 ?m, simultaneously. The instrument employs three arrays-one 512 × 512 SITe CCD and two 256 × 256 SBRC InSb arrays-to cover the three channels. It has been commissioned in the imaging, spectroscopic, and polarimetric modes on the United Kingdom Infrared Telescope, the University of Hawaii 2.2 m telescope, and the Okayama Astrophysical Observatory 1.88 m telescope since 1999 June.

We present a study of the newly discovered McNeil’s nebula in Orion using simultaneous observations of the $JHK_{\mathrm{s}}$-bands with the near-infrared (NIR) camera SIRIUS on the IRSF 1.4m telescope. The cometary infrared nebula is clearly seen extending toward both north and south from the NIR source (V1647 Orionis), which illuminates McNeil’s nebula. The compact nebula has an apparent diameter of about $70 {}^{\prime \prime }$. The nebula is blue (bright in $J$) and has a cavity structure with two rims extending toward the north-east and the north-west. The north-east rim is brighter and sharp, while the north-west rim is diffuse. The north-east rim can be traced out to $\sim 40 {{}^{\prime \prime }}$from the location of the NIR source. In contrast, no cavity structure can be seen toward the south, although the diffuse nebula is extended out to $\sim 20 {{}^{\prime \prime }}$. New NIR photometric data show a significant variation in the magnitudes ($\gt 0.15 \,\mathrm{mag} > 0.15 \,\mathrm{mag}$) of the source of McNeil’s nebula within a period of one week, which is possibly under the phase of eruptive variables, like FUors or EXors.

We studied the evolution of elliptical galaxies at $z \gtrsim 1$using a sample of 247 Extremely Red Objects (EROs) with $R-K_\mathrm{s} \ge 3.35$(AB) and $K_\mathrm{s} \le 22.1$(AB) constructed from $BVR \, i'z'JHK_\mathrm{s}$multicolor data of a $114 \,\mathrm{arcmin}^2$area in the Subaru/XMM-Newton Deep Field taken with the Subaru Telescope and the UH 2.2 m telescope. By fitting template spectra of old galaxies (OGs) and young, dusty starbursts (DSs) to the multicolor data, we classified EROs into these two classes and estimated their redshifts. We found that 58% of the EROs in our sample belong to the OG class and that these OGs have a wide range of colors at any redshift. We derived rest-frame $B$-band luminosity functions of OGs in our sample at $z=1 \hbox{-} 1.5$and $1.5 \hbox{-} 2.5$, and found that the number density of galaxies obeying passive evolution drops at $z \gtrsim 1.5$by a factor of three or more. The spatial correlation length of OGs is estimated to be $r_0 \gtrsim 8 \,h^{-1} \,\mathrm{Mpc}$, which is comparable to, or larger than, those of present-day early-type galaxies of similar luminosities. We also discussed properties of DSs in our data.

The star-forming region S269 is studied with deep JHKs and H2 v = 1-0 S(1) images and K-band spectroscopy. The JHKs images reveal a rich embedded cluster at the center of the field; most stars in the cluster are located in two major congregations. The colors of the two congregations and of the associated nebulosities are quite different. The color-color diagrams and color-magnitude diagrams of the two subgroups show that their intrinsic colors are not significantly different, suggesting that they could be formed at a similar age. Between the subgroups there are two near-infrared sources, IRS 2e and 2w. Their K-band spectra rise toward longer wavelengths, indicative of a dense dusty envelope surrounding them. Strong H2 and Brg lines are detected on these two objects. A poorly collimated bipolar H2 jet has been detected around IRS 2e and 2w. The morphology of the infrared jet and K-band spectra of the two infrared sources suggest that the jet is likely driven by IRS 2e or 2w, or both. Several lines of evidence suggest that IRS 2e and 2w are massive young stellar objects probably younger than most of the stars in the region. Given the facts above, we speculate that lower mass star-forming activities in a stellar cluster could play an important role in the formation of a massive star.

We present optical and near-infrared spectropolarimetry of the nuclei of four type 2 Seyfert galaxies, Mrk 463E, Mrk 1210, NGC 1068, and NGC 4388. The data were obtained simultaneously, covering the wavelength range of 0.46-2.5 mm. We model the polarizations from two dust-scattering components: (1) scattering in dusty regions in ionization cones and (2) scattering in a torus surrounding a type 1 nucleus. The polarizations from electron scattering in the cones and dichroic absorption by aligned dust grains in the torus are also compared with the observations. We confirmed that a combination of electron and dust scattering in the ionization cones is the preferred mechanism for the optical continuum polarization. For the near-infrared, dichroic absorption by aligned grains can explain the continuum polarization of Mrk 463E and Mrk 1210 as well as NGC 1068. Visual optical depths of the order of 10-20 are estimated for dichroic absorption in these nuclei. Dust scattering in the torus, whose grain size distribution is assumed to be the same as in the Galactic diffuse interstellar medium, cannot reproduce the observed spectral slope of the near-infrared polarization and total nuclear flux simultaneously. However, this might only indicate that the grain size distribution in the torus of active galactic nuclei (AGNs) is different, and dust scattering with moderate optical depth and dominated by large grains might provide a reasonable explanation for the near-infrared radiation from AGNs.

We conducted a deep JHKs-band imaging survey of the M17 region, using a near-infrared camera, the Simultaneous 3-color InfraRed Imager for Unbiased Survey (SIRIUS), mounted on the InfraRed Survey Facility (IRSF) 1.4 m telescope at the South African Astronomical Observatory. This survey covers an area of ~200 arcmin2 with 10 s limiting magnitudes of J ~ 18.7, H ~ 18.2, and Ks ~ 17.5. The near-infrared (NIR) images reveal an unprecedented view of the region. The NIR nebulae are highly structured, with two nebular bars corresponding to, but a little larger than, the H II region defined by Felli, Massi, & Churchwell, constructing a conical shape. Fine structures are found all over the nebular area. The central region contains a congregation of intermediate- to high-mass stars. From the slope of the Ks-band luminosity function and the frequency of young stellar objects (YSOs) we infer that the central cluster has an age less than 3 Myr. The central OB cluster provides tremendous energy that heats and ionizes its surrounding materials, triggering the star formation of second-generation in the nebular bars. The second generation stars are so numerous that could they affect the star formation efficiency in the whole region. To the southwest of the central cluster and the nebular bars, where a giant molecular cloud core is located, a large number of red stars are detected. We argue that these red stars are most probably associated YSOs with intrinsic color excesses, not normal field stars reddened by the molecular cloud in front of them. Being located beyond the photodissociation region, the star-forming process in the molecular region could be independent of the impact of the central cluster.

We have carried out near-infrared mapping observations of photodissociation regions in M17 with the Wide Field Cryogenic Telescope and CO (J = 1-0) observations in three isotope lines with the "NANTEN" telescope. The observations covered an area of 20' x 20' with a spatial resolution of 5.''6 for near-infrared wavelengths and with a half-power beamwidth of 2.'7 for millimeter wavelengths. We detected 38 sources brighter than 7 mag at 3.67 mm (Ln band), five of which show signs of young stellar objects. We have detected two emission bars (the N bar and the S bar) in all four near-infrared bands (J, K, Ln, and 3.3 mm). Their spatial distributions differ considerably from band to band, and we have compared them with the radio continuum, the mid-infrared data, and the CO molecular line emission. The different brightness and spectral energy distributions at near-infrared wavelengths can be well explained by emission from hot dust and ionized gas together with obscuration by local cold dust with a steep gradient from north to south. In the N bar, the free-free emission from ionized gas dominates at shorter wavelengths (J and K) and there is little extinction, whereas in the S bar, the free-free emission is attenuated at shorter wavelengths by the heavy local extinction. In both the N and S bars, the thermal emission from hot dust at around 1000 K dominates in the Ln band. The 3.3 mm unidentified infrared (UIR) emission delineates photodissociation regions between the H II regions and the surrounding molecular clouds. The UIR intensity decreases exponentially from the UIR peak toward the molecular clouds, with scale lengths of 88'' and 100'', or 0.9 and 1.0 pc, at the N and the S bars, respectively. Far-ultraviolet photons, which excite UIR emission, penetrate into the molecular clouds for ~1 pc, in the nearly edge-on geometry. The 12CO contours are elongated in the direction northwest-southeast, while the C18O contours are round. Far-ultraviolet photons erode the tenuous portions (as seen in 12CO) of the surface of the cloud and penetrate deeply toward the denser inside, forming complex structures in the photodissociation regions bordering the molecular cloud.

We constructed a wide field cryogenic telescope (WFCT) containing a whole Ritchey-Chrétien system and a focal plane array in a cryostat for near infrared observations to cover the field of view of 0.4°. The telescope has a primary mirror of 220 mm and an engineering grade 256 × 256 InSb array. The optical components such as two mirrors, filters, spiders, and radiation shield tube are cooled down to 180 K as well as the InSb array to 35 K by a mechanical refrigerator. We show the results of the background surface brightnesses and the limiting magnitudes at 3.3 and 3.67 μm measured at Sutherland, South Africa. We describe the on-going upgrade of this instrument, equipped with a 1024 × 1024 ALADDIN InSb science grade array.

Near-infrared polarimetric images are presented for six molecular outflow sources: IRAS 20050+2720, IRAS 20126+4104, IRAS 20188+3928, S233, AFGL 5180, and AFGL 6366S. All the regions are found to exhibit reflection nebulae and to be associated with massive and clustered star formation. By inspecting polarimetric patterns in the nebulae, we have identified six deeply embedded sources (DESs) which illuminate circumstellar nebulosity but are not detectable in wavelengths shorter than 2 mm. While the DES in IRAS 20050 coincides with an infrared source in a previous, longer wavelength observation and the one in IRAS 20126 with a hot molecular core, the nature of the other newly discovered DESs is not known. From the compilation of the observations of DESs over a large wavelength range, we suspect that the DESs possess characteristics similar to hot molecular cores and are likely to be in the pre-ultracompact H II region phase of massive star formation.

We present near-infrared spectropolarimetric data between 0.9 and 4.2 mm for three prototypes of low-mass young stellar objects (YSOs), L1551 IRS 5, HL Tau, and T Tau in the Taurus dark cloud. These sources are in different classes in the standard spectral classification scheme of low-mass YSOs by Lada. The polarization curves of the observed sources show distinct differences. The class I protostar L1551 IRS 5 shows a flat polarization curve with high polarization through the observed wavelengths. It also shows a polarization excess at the 3.1 mm ice band absorption feature. The "flat-spectrum source" HL Tau, which is thought to be in a transient phase from class I to class II, shows a steep decrease of polarization with increasing wavelengths from 1.0 to 2.5 mm, while it shows a flat polarization curve with high polarization in optical wavelengths and a slowly decreasing slope with small polarization in 3-4 mm. The class II source T Tau displays small polarization no more than 2% through the observed wavelengths; the polarization in the shorter wavelengths from optical to 1.3 mm decreases with increasing wavelengths. T Tau also shows an increasing polarization curve in the longer wavelengths over 1.6 mm, which is most likely to come from the infrared companion T Tau S (Kobayashi et al.). The prominent differences of the observed near-infrared polarization curves can be clearly understood in terms of the standard spectral classification scheme of low-mass YSOs. Thus near-infrared spectropolarimetry could serve as a potentially powerful diagnostic of circumstellar material, complementary to the standard spectral classification.

We present the 1.2–4.2 μm spectroscopy of stars found in an objective prism survey of the galactic plane by Stephenson (1992, AAA 55.002.010). These stars were thought by Stephenson to be heavily reddened by interstellar absorption. However, almost all of them have turned out to be late-type stars with clear 2.3 μm CO absorption, which means that they are intrinsically red as well. A few stars have AV∼ 9, but most of them are only moderately reddened (AV= 1–5).

We present near-infrared spectropolarimetric data between 0.9 and 4.2 mm for T Tauri. The data clearly show two polarization components: one has a position angle of ~90deg at wavelengths shortward of ~1.6 mm, while the other has a position angle of ~20deg at wavelengths longward of ~1.6 mm. The degree of polarization of the former component decreases as the wavelength increases, while the reverse occurs for the latter component. Because the polarization position angle rotates gradually from 1.4 to 1.8 mm, the rotation can probably be explained by a combination of several scattering components and/or dichroic extinction. In addition, an enhancement of the polarization of the longer wavelength component was clearly observed in 1990 January, when T Tau's infrared companion, T Tau S, was in the outburst phase. The polarization increased to about 3 times that of the quiescent phase at 1.4-2.4 mm. The enhancement of the polarization in the brighter phase of T Tau S means that T Tau S is a highly polarized source. We estimate the polarization of T Tau S in the K band (2.2 mm) at 5.7% +- 1.3%, assuming that the polarization is constant in both the quiescent and the outburst phase. This high polarization suggests that the polarization originates from scattering by a compact nebulosity in the vicinity of T Tau S. In view of the high polarization resulting from the scattering, we suggest that the infrared companion T Tau S is an embedded protostellar object.

LEWIS (L, M-band Echelle Wide coverage Intermediate-resolution Spectrometer) is an infrared spectrograph designed primarily for spectroscopy in the 2.0 - 5.0 micron region. It is capable of covering the whole L-band (2.8 micron - 4.2 micron) or M-band (4.5 micron - 5.0 micron) in one exposure with a resolving power over 1250 by using both a prism and a grating to produce a cross-dispersed echelle-type spectrogram onto a Santa Barbara Research Center (SBRC) 256X256 InSb array. The grating is characterized by a large groove of spacing of 125 microns and is utilized at very high orders (25th - 37th in the L-band). The achieved throughput of the spectrograph including the quantum efficiency of the detector is about 20%.

We present an analysis of 1- to 5-μm, near-infrared broadband images of Comet P/Halley 1986 III covering a 104-km square region of the inner coma obtained on three consecutive nights in 1986 March during post-perihelion passage. In all images, the coma is extended in the sunward direction and appears distinctly non-spherical, similar to morphology in the 10-μm made by Haywardet al.(1987) 3.0 days later during theGiottoencounter. Marked variation in the coma's overall structure and brightness also was apparent, including the presence of a jet feature which we associate with a short-term outburst of material from the comet nucleus. The observed coma surface brightness dependence upon nucleocentric distance (r) at all wavelengths in both the comet dust tail and in the jet deviates from the dependence predicted by the “steady state” model for comet nucleus ablation, with the radial decrease in surface brightness being slower thanr−1on the jet side of the nucleus and faster thatr−1on the tail side. The near-infrared colors of the coma are not constant as a function of nucleocentric distance, suggesting that the grain properties are not uniform across the coma. Based on an elementary dynamical analysis of the trajectories of dust particles ablated from the nucleus we argue that these observations may be consistent with the hypothesis that particles emitted in jets fragments in the outflow on time scales of a few hours.