Relativistic jet activity from the tidal disruption of a star by a massive black hole.

Supermassive black holes have powerful gravitational fields with strong gradients that can destroy stars that get too close, producing a bright flare in ultraviolet and X-ray spectral regions from stellar debris that forms an accretion disk around the black hole. The aftermath of this process may have been seen several times over the past two decades in the form of sparsely sampled, slowly fading emission from distant galaxies, but the onset of the stellar disruption event has not hitherto been observed. Here we report observations of a bright X-ray flare from the extragalactic transient Swift J164449.3+573451. This source increased in brightness in the X-ray band by a factor of at least 10,000 since 1990 and by a factor of at least 100 since early 2010. We conclude that we have captured the onset of relativistic jet activity from a supermassive black hole. A companion paper comes to similar conclusions on the basis of radio observations. This event is probably due to the tidal disruption of a star falling into a supermassive black hole, but the detailed behaviour differs from current theoretical models of such events.

An experimental setup for creating and imaging 4He2 * excimer cluster tracers in superfluid helium-4 via neutron-3He absorption reaction.

For the purpose of future visualization of the flow field in superfluid helium-4, clusters of the triplet state excimer 4He2 * are generated along the micro-scale recoil tracks of the neutron-absorption reaction n + 3He → 3T + p. This reaction is induced by neutron irradiation of the 3He fraction contained in natural isotopic abundance liquid helium with neutron beams either from the Japan Proton Accelerator Research Complex, Materials and Life Science Experimental Facility (JPARC)/Materials and Life Science Experimental Facility or from the Kyoto University Institute for Integrated Radiation and Nuclear Science. These 4He2 * clusters are expected to be ideal tracers of the normal-fluid component in superfluid helium with several advantageous properties. Evidence of the excimer generation is inferred by detection of laser induced fluorescence emitted from the 4He2 * clusters excited by a purpose-built short pulse gain-switched titanium:sapphire (Ti:sa) laser operating at a wavelength of 905 nm. The setup and performance characteristics of the laser system including the Ti:sa and two continuous wave re-pumping lasers are described. Detection at the fluorescence wavelength of 640 nm is performed by using optical bandpass filtered photomultiplier tubes (PMT). Electrical noise in the PMT acquisition traces could successfully be suppressed by post-processing with a simple algorithm. Despite other laser-related backgrounds, the excimer was clearly identified by its fluorescence decay characteristics. Production of the excimer was found to be proportional to the neutron flux, adjusted via insertion of different collimators into the neutron beam. These observations suggest that the apparatus we constructed does function in the expected manner and, therefore, has the potential for groundbreaking turbulence research with superfluid helium.

Analysis of electroretinogram during systemic hypercapnia with intraretinal K(+)-microelectrodes in cats.

PURPOSE: Systemic hypercapnia alters the intraretinal pH and metabolism and profoundly affects the vitreal electroretinogram (ERG). Using intraretinal K(+)-selective microelectrodes (ISMs), the authors examined the effects of systemic hypercapnia on ERG in the intact cat eye in vivo. METHODS: Double-barreled K(+)-ISMs were used to record intraretinal, light-evoked [K+]o decrease, intraretinal ERG, vitreal ERG, and standing potential (SP) in the dark-adapted retina. Hypercapnia was induced by adding CO2 to the inhaled mixture of gas (without significant hypoxia). RESULTS: The standing potential was elevated, and the vitreal ERG c-wave increased in amplitude whereas the b-wave decreased during hypercapnia. Intraretinal recordings showed that the amplitudes of slow PIII and the transepithelial (TEP) c-wave decreased. The slow PIII decreased more than the TEP c-wave. The light-evoked [K+]o decrease also was reduced, but no change was noted in the subretinal [K+]o. CONCLUSION: The neural retina was more sensitive than the retinal pigment epithelium to the intraretinal acidification caused by systemic hypercapnia. However, the change in the SP and b-wave suggested complicated effects other than acidosis.

Intraretinal study of cat electroretinogram during retinal ischemia-reperfusion with extracellular K+ concentration microelectrodes.

PURPOSE: Intraretinal electroretinograms (ERG) during retinal ischemia-reperfusion were analyzed to clarify which cells are affected in the cat dark-adapted eye. METHODS: Ischemia was induced by raising the intraocular pressure above arterial systolic pressure in vivo. Double-barreled microelectrodes were used to record the intraretinal ERGs and the light-evoked [K+]o decrease in the subretinal space. Vitreal ERGs, the standing potential and the transepithelial resistance were also recorded. RESULTS: After 10 minutes of ischemia, vitreal ERG b- and c-waves had recovered fully in 2 hours, and after 30 minutes of ischemia, recovered approximately 85% and 77% of their control amplitudes in 4 hours, respectively. At the early period of reperfusion after 10 minutes of ischemia we observed the supernormal c-wave (124% of its control amplitude, n = 10) with an elevated standing potential. The transepithelial potential (TEP) c-wave increased without changes of slow PIII and transepithelial resistance when the supernormal amplitudes occurred. The light-evoked [K+]o decrease in the subretinal space (90% retinal depth) in the area centralis recovered to about 90% of the control amplitude in 2 hours, and after 30 minutes of ischemia recovered to about 70% of the control amplitudes in 4 hours. The recovery courses of the slow PIII and TEP c-wave were almost the same as that of the light-evoked [K+]o decrease. CONCLUSIONS: The temporary supernormal amplitude of the ERG c-wave was originated from the retinal pigment epithelium (RPE) during the early period of reperfusion after 10 minutes of ischemia. The photoreceptors, Muller cell and RPE are responsible for the changes in the light-evoked [K+]o decrease, a slow PIII and TEP c-wave, respectively. Intraretinal recordings suggested that after ischemia of 10 to 30 minutes duration, the responses of photoreceptors, Muller cells and the RPE recovered with a similar time course. These findings suggest that in all cases, primarily photoreceptors were damaged.

Effects of ornithine on the electroretinogram in cat retina.

PURPOSE: To study the acute effects of L-ornithine hydrochloride on the function of cat retina in vivo. METHODS: A small amount of ornithine was administered intravitreously or intravenously. Changes in retinal function were monitored by vitreal electroretinogram (ERG) and intraretinal ERG with K(+)-selective microelectrodes. RESULTS: Intravitreal injections (0.2 to 0.5 M; 15 microliters) of ornithine caused a decrease in the standing potential and the vitreal ERG c-wave amplitude. The ERG c-wave decreased continuously during a 5-hour period. Intravenous injection (0.2 M; 10 ml) of ornithine also diminished the c-wave. Intraretinal recording showed that the amplitudes of the retinal pigment epithelium (RPE) component and the Müller cell component of the ERG c-wave were reduced after intravitreal injection. The light-evoked [K+]o decrease in the subretinal space did not change. The change in transepithelial resistance contributed little to the decrease in the c-wave. CONCLUSION: These results demonstrated that ornithine selectively affects the c-wave and suggested that it affects RPE and Müller cells directly without affecting photoreceptors.

Roles of constitutive nitric oxide synthase in postischemic rat retina.

PURPOSE: Nitric oxide is a reactive species that could be protective or destructive to the retina depending on the stage of the evolving ischemic process. This study was conducted to obtain a better understanding of the roles of constitutive nitric oxide synthase (cNOS) during reperfusion after ischemia in rat retina. METHODS: Retinal ischemia was induced for 60 minutes in Sprague-Dawley rats by ligating the optic nerve. Gene expression for endothelial and neuronal nitric oxide synthases (eNOS and nNOS) was studied by reverse transcription-polymerase chain reaction (RT-PCR). To inhibit cNOS, NG-nitro-L-arginine (L-NNA) was injected intraperitoneally four times (every 6 hours) beginning 2 hours after reperfusion, for a total dose of 80 mg/kg. Retinal damage was assessed by the rate of a- and b-wave recovery on electroretinograms and by the thickness of the retinal layers. Retinal circulation and vessel diameter were evaluated by the dye-dilution technique. RESULTS: After ischemia ended, eNOS mRNA initially decreased until 6 hours, then increased to a peak at 12 hours, and decreased progressively beyond 24 hours until the final measurement at 96 hours of reperfusion. nNOS mRNA decreased to nearly undetectable levels during the same measurement periods. L-NNA treatment enhanced reduction of a- and b-wave amplitudes and increased thinning of the inner retina in postischemic eyes. Retinal mean circulation time was markedly prolonged in L-NNA-treated postischemic eyes. Arterial mean transit times were 2.1-fold and 4.5-fold longer in L-NNA-treated postischemic eyes than in L-NNA-treated nonischemic eyes and in D-NNA-treated postischemic eyes, respectively. CONCLUSIONS: This study shows that postischemic inhibition of NOS worsens retinal damage after ischemia-reperfusion and alters postischemic retinal circulation. Nitric oxide may play an important role in protecting the retina from ischemic injury, possibly by preventing postischemic hypoperfusion.

Prognostic factors for hypotensive effects of isopropyl unoprostone in eyes with primary open-angle glaucoma.

It has been reported that isopropyl unoprostone, a prostaglandin-related compound, has potent effects in lowering intraocular pressure and that its hypotensive effect is an increase of uveoscleral outflow. In the present study, we investigated the clinical characteristics of the hypotensive effects of this novel antiglaucoma drug in 115 primary open-angle glaucoma (POAG) eyes. The mean intraocular pressure (+/- standard deviation) before the addition of isopropyl unoprostone to the current regimens was 21.3 +/- 4.4 mmHg. The values at 1 month, 3 months, and 6 months after treatment were, respectively, 20.2 +/- 3.9 mmHg, 19.4 +/- 3.4 mmHg, and 18.4 +/- 2.5 mmHg. In POAG, the outflow pressure difference (delta OP), which is determined as (pretreatment pressure - posttreatment pressure)/(pretreatment pressure - 10) x 100 (%), was reduced by more than 20% in 36 (31%) of 115 eyes, 35 (36%) of 97 eyes, and 33 (53%) of 62 eyes, respectively at 1, 3, and 6 months. We defined the "early success" group as eyes with a significant reduction in delta OP (> or = 20%) at 1-month posttreatment. To identify the prognostic factors related to the significant reduction in intraocular pressure occurring after the administration of this drug, we carried out a statistical analysis by logistic regression analysis. Statistical analysis revealed significant prognostic factors: history of cataract surgery (P = 0.0084) and pretreatment pressure levels (P = 0.0105) at 1-month posttreatment. Also, further statistical analysis showed a significant influence of pretreatment pressure levels (P = 0.0010) at 3 months posttreatment. Our study shows an interindividual difference in the responsiveness of hypotensive effects on POAG eyes and some prognostic factors (history of cataract surgery and pretreatment pressure levels) prior to the use of this drug.

[Organometal-catalyzed asymmetric synthesis stereocontrolled by organosulfur functionality].

Our recent studies on asymmetric synthesis with the assistance of organometal catalysts stereocontrolled by organosulfur functionality involved in reaction substrates or ligands are reviewed. The studies focused on asymmetric synthesis via chiral pi-allylmetal complexes derived from (S)-proline allyl ester, olefinic cyclopropanes, chiral 2-alkynyl sulfinates, and chiral new ligands, and also focused on asymmetric cycloaddition reactions with chiral sulfoxides and sulfinates, such as intramolecular ene, metallo-type ene, and hetero Diels-Alder reactions. Participation of organosulfur functionality in organometal-catalyzed asymmetric reactions was unveiled on the basis of the stereochemical outcomes obtained.

[Stereochemistry of highly selective transition metal or Lewis acid-catalyzed asymmetric reactions].

Recent progress of our studies on catalytic asymmetric synthesis is reviewed focused on transition metal-catalyzed intramolecular asymmetric reactions using chiral organo-sulfur groups as main chiral auxiliaries such as asymmetric vinyl-cyclopropane-cyclopentene rearrangements and intramolecular asymmetric metallo-ene reactions, Lewis acid-catalyzed intramolecular asymmetric ene reactions with chiral sulfinyl groups, and palladium-catalyzed intramolecular asymmetric allylations via chiral enamines.

[Effect of L-ascorbic acid 2-phosphate on cultured rabbit keratocytes (the third report). The effect on production and secretion of type I collagen].

We examined the effect of L-ascorbic acid 2-phosphate (P-Asc), a long-acting phosphate derivative of L-ascorbic acid, on intracellular distribution and production of type I collagen in cultured rabbit keratocytes by an immunohistochemistry and enzyme immunoassay. Exposure of 0.1 mM P-Asc for 10 hours decreased a type I collagen immunoreactivity of the cytoplasm as stained in fine granular materials. 0.1 mM P-Asc induced increase of type I collagen level in the medium. The results suggested that 0.1 mM P-Asc might increase the biosynthesis and secretion of type I collagen in keratocytes and have a therapeutic effect on corneal stromal damage.

[Effect of L-ascorbic acid 2-phosphate on cultured rabbit keratocytes (the second report)].

We examined the effect of L-ascorbic acid 2-phosphate (P-Asc) on the proliferation of cultured rabbit keratocytes. P-Asc is a derivative of L-ascorbic acid and it yields more prolonged effects of vitamin C in solution than L-ascorbic acid. The proliferation of cultured rabbit keratocytes was promoted by the presence of P-Asc in culture medium for 10, 20, and 30 days. Transmission electron microscopic observations revealed that the cells were more multilayered in the presence of P-Asc (0.1mM) for thirty days than those in the absence of P-Asc. Moreover, this effect of P-Asc was attenuated by azetidine 2-carboxylic acid which is an inhibitor of collagen synthesis. Hence, it is suggested that the promotive effect of P-Asc on the growth of cultured keratocytes is related to the synthesis of collagen. Based on our observations, P-Asc may have a therapeutic effect on corneal stromal damages such as a corneal chemical burn and surgical trauma.

[Detection of HTLV-1 provirus DNA in T-cell neoplasms].

Using polymerase chain reaction (PCR) amplification and Southern hybridization, gag, pol, env and pX region genes of HTLV-1 provirus were detected in T-cell malignancy such as adult T-cell leukemia/lymphoma (ATLL), mycosis fungoides in leukemic phase (MF) and, CD8-leukemia. The gag, pol, and/or env regions, were not amplified in some cases of ATLL, which was considered to be induced by mutation, but not deletion. However, the pX-1 and pX-2 regions could be amplified in all cases examined. As it is suggested that the pX gene plays an important role in leukemogenesis, the mutation may not occur in this region gene. Interestingly, the pX-2 was amplified in the cases with MF and CD8-leukemia as well. The amplified products were hybridized to the HTLV-1 pX sequence, even though the products contained DNA fragments with a size larger than expected as well as those of an expected size. These results indicated the possibility that the virus having sequence identical with HTLV-1 pX is integrated in the tumor cells of MF and CD8 leukemia.

Effects of iodate on intraretinal b and c waves of the cat electroretinogram.

In 12 cats, the intravenous and intravitreal administrations of sodium iodate (SI) were performed to examine the effects on b and c waves of electroretinogram in the dark-adapted retina. The intravitreal SI (0.5-3.5 mM) produced the complete suppression of intraretinal b waves without remarkable changes of slow PIII and light-evoked [K+]o decrease in the subretinal space. Intravenous SI (30 mg/kg) also showed the suppression of intraretinal b waves. SI not only acted as a poison to the retinal pigment epithelium but also might block the post-synaptic response.

Effects of ischemia-reperfusion on light-evoked alkalinization outside rod photoreceptors in the cat retina.

The effects of ischemia-reperfusion on the light-evoked alkalinization, which reflects the metabolism of rod photoreceptors, were studied in the dark-adapted cat retina in vivo. We recorded the pH value in the extracellular space surrounding rod photoreceptors with double-barreled H(+)-selective microelectrodes. The light-evoked alkalinizations at the outer nuclear layer were diminished during reperfusion after 10-30 min of ischemia which was induced by an increase of the intraocular pressure above the arterial systolic pressure. This result suggests that the rod metabolism might be suppressed during reperfusion after ischemia.