A nearby long gamma-ray burst from a merger of compact objects.

Gamma-ray bursts (GRBs) are flashes of high-energy radiation arising from energetic cosmic explosions. Bursts of long (greater than two seconds) duration are produced by the core-collapse of massive stars1, and those of short (less than two seconds) duration by the merger of compact objects, such as two neutron stars2. A third class of events with hybrid high-energy properties was identified3, but never conclusively linked to a stellar progenitor. The lack of bright supernovae rules out typical core-collapse explosions4-6, but their distance scales prevent sensitive searches for direct signatures of a progenitor system. Only tentative evidence for a kilonova has been presented7,8. Here we report observations of the exceptionally bright GRB 211211A, which classify it as a hybrid event and constrain its distance scale to only 346 megaparsecs. Our measurements indicate that its lower-energy (from ultraviolet to near-infrared) counterpart is powered by a luminous (approximately 1042 erg per second) kilonova possibly formed in the ejecta of a compact object merger.

An electrically resistive sheet of glial cells for amplifying signals of neuronal extracellular recordings.

Electrical signals of neuronal cells can be recorded non-invasively and with a high degree of temporal resolution using multielectrode arrays (MEAs). However, signals that are recorded with these devices are small, usually 0.01%-0.1% of intracellular recordings. Here, we show that the amplitude of neuronal signals recorded with MEA devices can be amplified by covering neuronal networks with an electrically resistive sheet. The resistive sheet used in this study is a monolayer of glial cells, supportive cells in the brain. The glial cells were grown on a collagen-gel film that is permeable to oxygen and other nutrients. The impedance of the glial sheet was measured by electrochemical impedance spectroscopy, and equivalent circuit simulations were performed to theoretically investigate the effect of covering the neurons with such a resistive sheet. Finally, the effect of the resistive glial sheet was confirmed experimentally, showing a 6-fold increase in neuronal signals. This technique feasibly amplifies signals of MEA recordings.

Unidirectional signal propagation in primary neurons micropatterned at a single-cell resolution.

The structure and connectivity of cultured neuronal networks can be controlled by using micropatterned surfaces. Here, we demonstrate that the direction of signal propagation can be precisely controlled at a single-cell resolution by growing primary neurons on micropatterns. To achieve this, we first examined the process by which axons develop and how synapses form in micropatterned primary neurons using immunocytochemistry. By aligning asymmetric micropatterns with a marginal gap, it was possible to pattern primary neurons with a directed polarization axis at the single-cell level. We then examined how synapses develop on micropatterned hippocampal neurons. Three types of micropatterns with different numbers of short paths for dendrite growth were compared. A normal development in synapse density was observed when micropatterns with three or more short paths were used. Finally, we performed double patch clamp recordings on micropatterned neurons to confirm that these synapses are indeed functional, and that the neuronal signal is transmitted unidirectionally in the intended orientation. This work provides a practical guideline for patterning single neurons to design functional neuronal networks in vitro with the direction of signal propagation being controlled.

Morphologic alteration of hepatocytes and sinusoidal endothelial cells in rat fatty liver during cold preservation and the protective effect of hepatocyte growth factor.

BACKGROUND: Fatty liver grafts are considered to be one of the main factors of primary nonfunctioning graft in transplantation. We investigated here, the hepatic damage during cold preservation in a rat fatty liver model by ultrastructural observation, and examined the effect of human recombinant hepatocyte growth factor (hrHGF) on amelioration of the cold-preserved graft condition. METHODS: Wistar rats were fed a choline-deficient diet (CDD) for 7 days. Livers were stored in cold University of Wisconsin (UW) solution for 0, 4, and 24 hr. We evaluated the ultrastructural alteration of the hepatocytes, sinusoidal architecture, and endothelial cells (SECs) by scanning and transmission electron microscopy. Ex vivo, we measured alanine aminotransferase (ALT) in first effluent as an index of hepatocyte injury and the hyaluronic uptake rate (HUR) as that of SEC damage. We injected hrHGF into rats fed CDD for 7 days through the portal vein and also added it to the UW solution to determine whether or not the agent ameliorated the hepatic damage in cold-preserved fatty livers. RESULTS: In rats fed CDD for 7 days, the lesion occupied by fat deposits appeared to enlarge with the duration of cold preservation leading to the disarrangement of sinusoidal architecture. Furthermore, sinusoidal endothelial damage, in which gaps, blebs, microvilli, and sinusoid denudation were detected, appeared to be more severe in these livers than in the corresponding control livers. ALT significantly increased in the 4-hr cold-preserved livers of rats fed CDD for 7 days. HUR decreased with 4-hr cold preservation and/or with CDD feeding. Administration of hrHGF prevented the expansion of fatty droplets and reduced SEC injury as detected by morphological observations. Increase of ALT in first effluent was inhibited to about one fourth the level observed in the 4-hr cold-preserved livers of rats fed CDD. Moreover, HUR significantly increased with the pretreatment of hrHGF. CONCLUSION: The hepatic injury in both hepatocytes and SECs in cold-preserved fatty liver graft developed more rapidly and severely than in the corresponding controls and demonstrated a protective effect of hrHGF.

Involvement of thromboxane A2-thromboxane A2 receptor system of the hepatic sinusoid in pathogenesis of cold preservation/reperfusion injury in the rat liver graft.

This study was designed to investigate the possible involvement of the thromboxane A2 (TXA2)-TXA2 receptor (TXA2R) system of the hepatic sinusoid in cold preservation/reperfusion injury in liver grafts. Rat livers were preserved in cold University of Wisconsin solution for either 6 or 24 hr. The number of TXA2Rs in sinusoidal endothelial cells isolated from 0-, 6-, and 24-hr preserved liver specimens was 22.50 +/- 1.80 x 10(3)/cell, 12.66 +/- 1.00 x 10(3)/cell, and 4.17 +/- 0.65 x 10(3)/cell, respectively. Kd and Bmax at 0 hr, 6 hr, and 24 hr of preservation were 8.54 +/- 1.26 nM and 37.34 +/- 3.01 fmol/10(6) cells, 7.08 +/- 1.14 nM and 12.66 +/- 1.00 fmol/10(6) cells, and 1.91 +/- 0.10 nM and 3.88 +/- 0.59 fmol/10(6) cells, respectively. The administration of OKY-046 (inhibitor of TXA2 synthesis) to the University of Wisconsin solution suppressed this reduction in TXA2R number. Furthermore, the concentration of TXA2 in hepatic sinusoid was decreased by OKY-046. In a reperfusion experiment, liver tissue preserved for 24 hr exhibited a higher reperfusion pressure, and effluent levels of both aspartate aminotransferase and lactate dehydrogenase were markedly elevated. The addition of OKY-046 to the preservation solution, however, prevented the rise in reperfusion pressure almost completely and the increase in effluent enzyme levels. This study showed that the TXA2Rs in sinusoidal endothelial cells were internalized through binding with TXA2 during cold preservation, causing activation of the TXA2-TXA2R system. This activation apparently induces an increase in reperfusion pressure, possibly due to sinusoidal contraction, resulting in microcirculatory disturbances.(ABSTRACT TRUNCATED AT 250 WORDS)

Decreased expression and rare somatic mutation of the CIP1/WAF1 gene in human hepatocellular carcinoma.

CIP1/WAF1, a critical downstream effector of tumor suppressor p53, encodes a cyclin-dependent kinase inhibitor. By Northern blot analysis, the CIP1/WAF1 mRNA level in the tumor was significantly lower than that in the corresponding normal liver from 19 Japanese patients with hepatocellular carcinoma (P < 0.05). In the tumor from only one out of 19 patients (5%), somatic mutations of the CIP1/WAF1 as well as that of p53 gene were identified by RT-PCR/SSCP analysis. These results suggest that the decreased CIP1/WAF1 expression is involved in the carcinogenesis or the progression of hepatocellular carcinoma.

Cooperativity of stabilized mRNA and enhanced translation activity in the cell-free system.

Detailed analysis of cell-free translation, coupled transcription-translation in static conditions and a continuous flow system based on E. coli S30 extracts was performed. Degradation of template mRNA was the predominant trigger to terminate the protein synthesis. In a coupled system, mRNA was preserved by repeated transcription whereas the starvation of nucleotide triphosphates led to the termination of protein synthesis in less than 1 h. In the CFCF system, NTP was held at the level of initial concentration and therefore did not arrest the translation for 15 h. The accurate coupling of transcriptional rate and translational rate was also crucial to enhance the efficiency of protein synthesis.

A novel macromolecular antibiotic, SN-07. Taxonomy of producing organism, isolation, characterization and biological activities.

A novel macromolecular antibiotic SN-07 was obtained from the cultural supernatant of Actinomadura roseoviolacea var. miuraensis nov. var. The antibiotic was soluble in water, had a molecular weight of 18,000-22,000 daltons in 50 mM Tris-HCl buffer, pH 7.0, containing 2.0 M KCl as compared with authentic proteins. Its major constituents were nucleic acids. The substance had antibacterial activity against Gram-positive bacteria. It was also effective against lymphocytic leukemia P388 in vivo.

Improvement of Escherichia coli cell-free system by utilization of cell extract having additional property. Problems and countermeasures.

In the Escherichia coli cell-free system, the modification of cell extract can be achieved by preparation of the strains carrying additional property or those being induced with a certain gene expression prior to harvesting. In this study, we analyzed the cell-free system with S30 extract containing T7 RNA polymerases (S30 extract-T7pol) prepared from E. coli BL21(DE3) strain, which includes T7 RNA polymerase from extrinsic genes by IPTG induction, as a model for the improvement of the cell-free system. The fact that a significant degree of mRNA degradation was observed in the cell-free system with S30 extract-T7pol indicates the increase of ribonuclease activity was an unfavorable influence derived from the cell-extract modification process. We also showed that this influence was settled by the addition of an effective ribonuclease inhibitor, such as copper (II) ion, to the reaction mixture.

Secretion of human epidermal growth factor (EGF) in autotrophic culture by a recombinant hydrogen-utilizing bacterium, Pseudomonas pseudoflava, carrying broad-host-range EGF secretion vector pKSEGF2.

We constructed the broad-host-range human epidermal growth factor (EGF) secretion plasmid pKSEGF2 by inserting the Escherichia coli tac promoter, the signal sequence of Pseudomonas stutzeri amylase, and the synthesized EGF gene into the broad-host-range vector pKT230. E. coli JM109 carrying pKSEGF2 secreted EGF into the periplasm and the culture medium under the control of the tac promoter. Pseudomonas aeruginosa PAO1161 carrying pKSEGF2 and Pseudomonas putida AC10 carrying pKSEGF2 secreted EGF into the culture medium constitutively. Four hydrogen-utilizing bacteria, Pseudomonas pseudoflava, Alcaligenes eutrophus, Alcaligenes paradoxus, and Paracoccus denitrificans, were transconjugated with pKSEGF2 from eight hydrogen-utilizing bacteria tested. In these transconjugated hydrogen-utilizing bacteria, P. pseudoflava carrying pKSEGF2 grew autotrophically and secreted EGF, confirmed by Western blot (immunoblot) analysis, into the culture medium constitutively.

Novel sensory adaptation mechanism in bacterial chemotaxis to oxygen and phosphotransferase substrates.

The involvement of methylation in the chemosensory response of bacteria to many attractants has been clearly established by studies in several laboratories. It has been assumed that adaptation of Salmonella typhimurium and Escherichia coli to all attractants involves methylation of a transmembrane methyl-accepting chemotaxis protein. The methyl donor in this reaction is S-adenosyl-L-methionine, and the protein methyltransferase is the product of the cheR gene. In contrast, adaptation to oxygen and phosphotransferase substrates were found to be independent of this methylation system. In E. coli AW660 (tsr tar trg), which lacks the known methyl-accepting chemotaxis proteins, chemotaxis was normal to oxygen and to substrates of the phosphotransferase system such as D-mannose, D-glucose, and N-acetyl-D-glucosamine. When S-adenosyl-L-methionine was depleted by methionine starvation or by addition of 1-aminocyclopentane-1-carboxylic acid, methylation-dependent adaptation to serine, aspartate, and ribose was defective in wild-type E. coli and S. typhimurium. However, adaptation to oxygen and phosphotransferase substrates was independent of S-adenosyl-L-methionine and the cheR product. These results suggest that there are methylation-independent and methylation-dependent mechanisms for sensory adaptation in bacteria.

Soft x-ray reflection from silicon and quartz mirrors.

The optical constants of silicon and quartz in the soft x-ray region (400-3750 eV) determined from the incidence-angle dependence of the specular reflectance are reported. The measured reflectance-vs-angle of incidence curves for the lower energies are quantitatively explained using a simple diffractive scattering model including the interference effect between the reflected beams, while those for the higher energies can be interpreted in terms of the microfacet model without the interference effect.

Bacillus cereus electron transport and proton motive force during aerotaxis.

Aerotaxis (migration towards oxygen) of Bacillus cereus M63, a motile strain, was inhibited by potassium cyanide and 2-heptyl-4-hydroxyquinoline N-oxide, indicating a requirement for both the terminal oxidase (cytochrome aa3) and the cytochrome b segment of the electron transport system. The concentration of oxygen that gave a half-maximal aerotactic response (K0.5) was 0.31 microM, which was similar to the Km for respiration (0.80 microM). The proton motive force increased from -135 to -177 mV when anaerobic cells were aerated, and it is proposed that the signal for aerotaxis is the increase in proton motive force that results from increased respiration. A strain of B. cereus T initially used in this study was immotile, grew as long chains of cells, and was deficient in autolytic enzyme. B. cereus M63 is a spontaneous derivative of B. cereus T that has normal motility.

Results of surgical treatment for recurrent hepatocellular carcinoma; comparison of outcome among patients with multicentric carcinogenesis, intrahepatic metastasis, and extrahepatic recurrence.

No consensus has been reached on the indications for and effectiveness of surgery for secondary intrahepatic hepatocellular carcinoma (HCC) and extrahepatic metastasis after macroscopically complete removal of primary HCC. Secondary intrahepatic HCCs, usually regarded as recurrence are classified into those arising as a result of multicentric carcinogenesis or intrahepatic metastases derived from the primary HCC. The present study was designed to evaluate the utility of surgical treatment in relation to the pathogenesis of the secondary HCC: classified as multicentric carcinogenesis (MC), intrahepatic metastasis (IM), and extrahepatic metastasis. Thirty patients underwent extirpation of secondary HCC: 22 patients had secondary HCCs in the remnant liver (MC group; n = 8; IM group, n = 14), 6 patients had extrahepatic metastases, and 2 patients had both intrahepatic and extrahepatic metastases. Survival rates after the re-resection in the 22 patients with the secondary intrahepatic HCCs were 94.7% at 1 year, and 50.2% at 3 years postoperatively, and the 8 patients with extrahepatic metastasis had survival rates of 62.5% at 1 year, 37.5% at 3 years, and at 5 years. The survival rates after re-resection in the MC group were 100% at 1 year and 80.0% at 3 years, whereas those in the IM group were 91.7% at 1 year, and 38.1% at 3 years. Surgery can be indicated not only in patients with localized intrahepatic secondary HCCs but also in those with extrahepatic metastasis. In particular, patients with secondary HCCs arising as a result of multicentric carcinogenesis are expected to have a good prognosis.

Inversion of aerotactic response in Escherichia coli deficient in cheB protein methylesterase.

Mutants of Escherichia coli and Salmonella typhimurium that were deficient in protein methylesterase activity encoded by cheB had an inverted response to oxygen; they were repelled by concentrations of oxygen that attract wild-type bacteria. Normal responses to oxygen and phosphotransferase substrates were observed in mutants that were deficient in protein methyltransferase (CheR) and the methyl-accepting transducing proteins (Tsr, Tar, Trg). However, the methylation-independent response to oxygen was modified by the loss of esterase activity. The inversion was apparently effected by the amidated Tsr protein present in cheB tsr+ mutants because aerotaxis was normal in cheB tsr strains. Chemotaxis to phosphotransferase sugars was normal in cheB mutants provided the extreme clockwise bias of the flagellar motors was modified to increase the probability of counterclockwise rotation.