Effect of recombination on genetic diversity of Caenorhabditis elegans

Greater molecular divergence and genetic diversity are present in regions of high recombination in many species. Studies describing the correlation between variant abundance and recombination rate have long focused on recombination in the context of linked selection models, whereby interference between linked sites under positive or negative selection reduces genetic diversity in regions of low recombination. Here, we show that indels, especially those of intermediate sizes, are enriched relative to single nucleotide polymorphisms in regions of high recombination in C. elegans. To explain this phenomenon, we reintroduce an alternative model that emphasizes the mutagenic effect of recombination. To extend the analysis, we examine the variants with a phylogenetic context and discuss how different models could be examined together. The number of variants generated by recombination in natural populations could be substantial including possibly the majority of some indel subtypes. Our work highlights the potential importance of a mutagenic effect of recombination, which could have a significant role in the shaping of natural genetic diversity.

Standardization of 129I using the movable 4πβ(LS)-X(NaI(Tl)) system

The ¹²⁹I standardization, using the movable 4πβ(LS)-X(NaI(Tl)) coincidence system, was performed for two ¹²⁹I radioactive sources - one was dissolved in 0.1M NaOH solution and the other in 0.1M HNO₃ solution. The system incorporates three movable PM tubes for a β-counter placed on a plane and a X-ray detector that can be moved up to the bottom of the vial. The β-efficiency depending on the amount of radioactive solution was investigated with 14 liquid scintillation samples prepared by gravimetrically dispensing 4.4-145 mg of ¹²⁹I radioactive solution. The β-efficiencies above 90% were observed at less than 56 mg, but it was at most 70% at 145 mg. This occurred regardless of the activity of the sample or the type of chemical solution used to dissolve ¹²⁹I source. The activity concentration of each ¹²⁹I source was determined by efficiency-extrapolation method for samples with an activity range of 0.28-4.5 kBq. The β-efficiency points were derived over 10 intervals by moving 3-PM tubes in fine steps of about 1 mm from the sample. The highest value for β-efficiency was 95%. The combined uncertainty were 0.25% and 0.26%, respectively. The stated precision obtained using the system is better than that previously reported in the literature obtained by the triple to double coincidence ratio (TDCR) or the CIEMAT/NIST efficiency tracing method.

Fast genetic mapping using insertion-deletion polymorphisms in Caenorhabditis elegans

Genetic mapping is used in forward genetics to narrow the list of candidate mutations and genes corresponding to the mutant phenotype of interest. Even with modern advances in biology such as efficient identification of candidate mutations by whole-genome sequencing, mapping remains critical in pinpointing the responsible mutation. Here we describe a simple, fast, and affordable mapping toolkit that is particularly suitable for mapping in Caenorhabditis elegans. This mapping method uses insertion-deletion polymorphisms or indels that could be easily detected instead of single nucleotide polymorphisms in commonly used Hawaiian CB4856 mapping strain. The materials and methods were optimized so that mapping could be performed using tiny amount of genetic material without growing many large populations of mutants for DNA purification. We performed mapping of previously known and unknown mutations to show strengths and weaknesses of this method and to present examples of completed mapping. For situations where Hawaiian CB4856 is unsuitable, we provide an annotated list of indels as a basis for fast and easy mapping using other wild isolates. Finally, we provide rationale for using this mapping method over other alternatives as a part of a comprehensive strategy also involving whole-genome sequencing and other methods.

Development of a movable 4πβ(LS)-γ coincidence counting system for activity standardization of β-γ emitters

A new movable 3PM-γ coincidence system, based on 4πβ(LS)-γ coincidence counting, for activity measurement of β-γ emitters has been designed at the Korea Research Institute of Standards and Science (KRISS). The system incorporates 3 PM tubes on the plane and two detectors placed above and below the center of the plane. The 3 PM tubes for β-counters in the plane are movable up to 100 mm from a liquid scintillation vial, thus enabling the variation of β-detection efficiencies by a geometrical technique. A NaI(Tl) γ-counter was set above for the present work. The β-event is determined by counting the logical sum of three double coincidences. All the necessary electronics, i.e., logical sum, adjusting the duration of dead-time of each counting channel and coincidence resolving times, and analyzing coincidence relation, were specially designed to be fabricated in an integrated circuit. Details of the detectors, the electronics, the overall movable 3PM-γ coincidence system are presented, as well as the results of investigations to assess its operating characteristics. Validation measurements have been performed with ⁶⁰Co and ⁵⁷Co sources. The highest β-detection efficiency achieved with ⁶⁰Co and ⁵⁷Co was 97% and 95%, respectively. The activity concentration determined with a new system agreed with calibrated values within the uncertainty range. Further results from validation measurements and the corresponding uncertainty budgets are presented.

Thermotolerance of tax-2 Is Uncoupled From Life Span Extension and Influenced by Temperature During Development in C. elegans

Thermotolerance of an organism is a complex trait that is influenced by a multitude of genetic and environmental factors. Many factors controlling thermotolerance in Caenorhabditis elegans are known to extend life. To understand the regulation of thermotolerance, we performed a genetic screen for mutants with better survival at warm temperature. Here we identified by dauer survival a tax-2 mutation and several mutations disrupting an insulin signaling pathway including the daf-2 gene. While the tax-2 mutant has improved thermotolerance and long life span, the newly identified daf-2 and other insulin signaling mutants, unlike the canonical daf-2(e1370), do not show improved thermotolerance despite being long-lived. Examination of tax-2 mutations and their mutant phenotypes suggest that the control of thermotolerance is not coupled with the control of life span or dauer survival. With genetic interaction studies, we concluded that tax-2 has complex roles in life span and dauer survival and that tax-2 is a negative regulator of thermotolerance independent of other known thermotolerance genes including those in the insulin signaling pathway. Moreover, cold growth temperature during development weakens the improved thermotolerance associated with tax-2 and other thermotolerance-inducing mutations. Together, this study reveals previously unknown genetic and environmental factors controlling thermotolerance and their complex relationship with life span regulation.

Publisher Correction: Electronic structure of the parent compound of superconducting infinite-layer nickelates

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Electronic structure of the parent compound of superconducting infinite-layer nickelates

The search continues for nickel oxide-based materials with electronic properties similar to cuprate high-temperature superconductors^1-10. The recent discovery of superconductivity in the doped infinite-layer nickelate NdNiO₂ (refs. ^11,12) has strengthened these efforts. Here, we use X-ray spectroscopy and density functional theory to show that the electronic structure of LaNiO₂ and NdNiO₂, while similar to the cuprates, includes significant distinctions. Unlike cuprates, the rare-earth spacer layer in the infinite-layer nickelate supports a weakly interacting three-dimensional 5d metallic state, which hybridizes with a quasi-two-dimensional, strongly correlated state with [Formula: see text] symmetry in the NiO₂ layers. Thus, the infinite-layer nickelate can be regarded as a sibling of the rare-earth intermetallics^13-15, which are well known for heavy fermion behaviour, where the NiO₂ correlated layers play an analogous role to the 4f states in rare-earth heavy fermion compounds. This Kondo- or Anderson-lattice-like 'oxide-intermetallic' replaces the Mott insulator as the reference state from which superconductivity emerges upon doping.

FUS Regulates Activity of MicroRNA-Mediated Gene Silencing

MicroRNA-mediated gene silencing is a fundamental mechanism in the regulation of gene expression. It remains unclear how the efficiency of RNA silencing could be influenced by RNA-binding proteins associated with the microRNA-induced silencing complex (miRISC). Here we report that fused in sarcoma (FUS), an RNA-binding protein linked to neurodegenerative diseases including amyotrophic lateral sclerosis (ALS), interacts with the core miRISC component AGO2 and is required for optimal microRNA-mediated gene silencing. FUS promotes gene silencing by binding to microRNA and mRNA targets, as illustrated by its action on miR-200c and its target ZEB1. A truncated mutant form of FUS that leads its carriers to an aggressive form of ALS, R495X, impairs microRNA-mediated gene silencing. The C. elegans homolog fust-1 also shares a conserved role in regulating the microRNA pathway. Collectively, our results suggest a role for FUS in regulating the activity of microRNA-mediated silencing.

Cell-type specific differences in promoter activity of the ALS-linked C9orf72 mouse ortholog

A hexanucleotide repeat expansion in the C9orf72 gene is the most common cause of inherited forms of the neurodegenerative disease amyotrophic lateral sclerosis (ALS). Both loss-of-function and gain-of-function mechanisms have been proposed to underlie this disease, but the pathogenic pathways are not fully understood. To better understand the involvement of different cell types in the pathogenesis of ALS, we systematically analyzed the distribution of promoter activity of the mouse ortholog of C9orf72 in the central nervous system. We demonstrate that C9orf72 promoter activity is widespread in both excitatory and inhibitory neurons as well as in oligodendrocytes and oligodendrocyte precursor cells. In contrast, few microglia and astrocytes exhibit detectable C9orf72 promoter activity. Although at a gross level, the distribution of C9orf72 promoter activity largely follows overall cellular density, we found that it is selectively enriched in subsets of neurons and glial cells that degenerate in ALS. Specifically, we show that C9orf72 promoter activity is enriched in corticospinal and spinal motor neurons as well as in oligodendrocytes in brain regions that are affected in ALS. These results suggest that cell autonomous changes in both neurons and glia may contribute to C9orf72-mediated disease, as has been shown for mutations in superoxide dismutase-1 (SOD1).

Effect of mutation mechanisms on variant composition and distribution in Caenorhabditis elegans

Genetic diversity is maintained by continuing generation and removal of variants. While examining over 800,000 DNA variants in wild isolates of Caenorhabditis elegans, we made a discovery that the proportions of variant types are not constant across the C. elegans genome. The variant proportion is defined as the fraction of a specific variant type (e.g. single nucleotide polymorphism (SNP) or indel) within a broader set of variants (e.g. all variants or all non-SNPs). The proportions of most variant types show a correlation with the recombination rate. These correlations can be explained as a result of a concerted action of two mutation mechanisms, which we named Morgan and Sanger mechanisms. The two proposed mechanisms act according to the distinct components of the recombination rate, specifically the genetic and physical distance. Regression analysis was used to explore the characteristics and contributions of the two mutation mechanisms. According to our model, ~20-40% of all mutations in C. elegans wild populations are derived from programmed meiotic double strand breaks, which precede chromosomal crossovers and thus may be the point of origin for the Morgan mechanism. A substantial part of the known correlation between the recombination rate and variant distribution appears to be caused by the mutations generated by the Morgan mechanism. Mathematically integrating the mutation model with background selection model gives a more complete depiction of how the variant landscape is shaped in C. elegans. Similar analysis should be possible in other species by examining the correlation between the recombination rate and variant landscape within the context of our mutation model.

Photoinduced Demagnetization and Insulator-to-Metal Transition in Ferromagnetic Insulating BaFeO_{3} Thin Films

We studied the electronic and magnetic dynamics of ferromagnetic insulating BaFeO_{3} thin films by using pump-probe time-resolved resonant x-ray reflectivity at the Fe 2p edge. By changing the excitation density, we found two distinctly different types of demagnetization with a clear threshold behavior. We assigned the demagnetization change from slow (∼150  ps) to fast (<70  ps) to a transition into a metallic state induced by laser excitation. These results provide a novel approach for locally tuning magnetic dynamics. In analogy to heat-assisted magnetic recording, metallization can locally tune the susceptibility for magnetic manipulation, allowing one to spatially encode magnetic information.

Relationship between early postoperative C-reactive protein elevation and long-term postoperative major adverse cardiovascular and cerebral events in patients undergoing off-pump coronary artery bypass graft surgery: a retrospective study

BACKGROUND

Inflammation plays a key role in the pathogenesis of vascular occlusive diseases, such as myocardial infarction and stroke. Additionally, these conditions are predicted by C-reactive protein (CRP), a general inflammation marker. We hypothesized that the inflammation induced by surgery itself augments vascular occlusive disease. We retrospectively evaluated the relationship between postoperative CRP elevation and postoperative major adverse cardiovascular and cerebral events (MACCE) in patients undergoing off-pump coronary artery bypass surgery (OPCAB).

METHODS

The electronic medical records of 1046 patients who underwent OPCAB were reviewed retrospectively. The relationship between postoperative serum CRP and long-term postoperative MACCE (median follow-up 28 months) was investigated.

RESULTS

Patients were divided into quartiles according to maximum postoperative CRP levels (<18, 18-22, 22-27, ≥27 mg dl(-1)). The adjusted hazard ratios (HRs) were 2.15, 2.45, and 2.81, respectively (P=0.004), compared with the lowest quartile (<18 mg dl(-1)). In the multivariate analysis, the postoperative CRP quartile (HR 2.81; P=0.004), postoperative non-use of statins (HR 1.86; P=0.003), and postoperative maximum troponin I (HR 1.02; P<0.001) independently predicted postoperative MACCE, while preoperative CRP did not (P=0.203). Several parameters were correlated with postoperative maximum CRP level: body temperature (P=0.001) and heart rate (P<0.001) at the end of surgery; intraoperative last lactate (P<0.001) and base excess (P<0.001); and red blood cell transfusion (P=0.019).

CONCLUSIONS

Postoperative CRP elevation was associated with long-term postoperative MACCE in OPCAB patients. This was mitigated by postoperative statin medication. Furthermore, postoperative CRP elevation was associated with intraoperative parameters reflecting hypoperfusion and inflammation.

Titanium dxy ferromagnetism at the LaAlO3/SrTiO3 interface

A number of recent transport and magnetization studies have shown signs of ferromagnetism in the LaAlO3/SrTiO3 heterostructure, an unexpected property with no bulk analogue in the constituent materials. However, no experiment thus far has provided direct information on the host of the magnetism. Here we report spectroscopic investigations of the magnetism using element-specific techniques, including X-ray magnetic circular dichroism and X-ray absorption spectroscopy, along with corresponding model calculations. We find direct evidence for in-plane ferromagnetic order at the interface, with Ti(3+) character in the dxy orbital of the anisotropic t2g band. These findings establish a striking example of emergent phenomena at oxide interfaces.

Strongly spin-orbit coupled two-dimensional electron gas emerging near the surface of polar semiconductors

We investigate the two-dimensional highly spin-polarized electron accumulation layers commonly appearing near the surface of n-type polar semiconductors BiTeX (X=I, Br, and Cl) by angular-resolved photoemission spectroscopy. Because of the polarity and the strong spin-orbit interaction built in the bulk atomic configurations, the quantized conduction-band subbands show giant Rashba-type spin splitting. The characteristic 2D confinement effect is clearly observed also in the valence bands down to the binding energy of 4 eV. The X-dependent Rashba spin-orbit coupling is directly estimated from the observed spin-split subbands, which roughly scales with the inverse of the band-gap size in BiTeX.

Intramyocardial transfer of hepatocyte growth factor as an adjunct to CABG: phase I clinical study

The purpose of this phase I clinical trial was to evaluate the safety, tolerability and potential efficacy of VM202, naked DNA expressing two isoforms of hepatocyte growth factor, as an adjunct therapy to coronary artery bypass grafting (CABG) in patients with ischemic heart disease (IHD). Nine patients were assigned to receive increasing doses (0.5 to 2.0 mg) of VM202 injected into the right coronary artery (RCA) territory following completion of CABG for the left coronary artery territory. Patients were evaluated for safety and tolerability, and changes in myocardial functions were monitored via echocardiography, cardiac magnetic resonance imaging and myocardial single photon emission computed tomography throughout 6-month follow-up period. No serious complication related to VM202 was observed throughout the 6-month follow-up period. Global myocardial functions (wall motion score index, P=0.0084; stress perfusion, P=0.0002) improved during the follow-up period. In the RCA region, there was an increase in the stress perfusion (baseline vs 3-month, P=0.024; baseline vs 6-month, P=0.024) and also in the wall thickness of the diastolic and systolic phases. Intramyocardial injection of VM202 can be safely used in IHD patients with the tolerable dose of 2.0 mg. In addition, VM202 might appear to have improved regional myocardial perfusion and wall thickness in the injected region.

Subband structure of a two-dimensional electron gas formed at the polar surface of the strong spin-orbit perovskite KTaO3

We demonstrate the formation of a two-dimensional electron gas (2DEG) at the (100) surface of the 5d transition-metal oxide KTaO3. From angle-resolved photoemission, we find that quantum confinement lifts the orbital degeneracy of the bulk band structure and leads to a 2DEG composed of ladders of subband states of both light and heavy carriers. Despite the strong spin-orbit coupling, our measurements provide a direct upper bound for the potential Rashba spin splitting of only Δk(parallel)}~0.02 Å(-1) at the Fermi level. The polar nature of the KTaO3(100) surface appears to help mediate the formation of the 2DEG as compared to nonpolar SrTiO3(100).

Emergent phenomena at oxide interfaces

Recent technical advances in the atomic-scale synthesis of oxide heterostructures have provided a fertile new ground for creating novel states at their interfaces. Different symmetry constraints can be used to design structures exhibiting phenomena not found in the bulk constituents. A characteristic feature is the reconstruction of the charge, spin and orbital states at interfaces on the nanometre scale. Examples such as interface superconductivity, magneto-electric coupling, and the quantum Hall effect in oxide heterostructures are representative of the scientific and technological opportunities in this rapidly emerging field.

Caenorhabditis elegans RNA-processing protein TDP-1 regulates protein homeostasis and life span

Transactive response DNA-binding protein (TARDBP/TDP-43), a heterogeneous nuclear ribonucleoprotein (hnRNP) with diverse activities, is a common denominator in several neurodegenerative disorders, including amyotrophic lateral sclerosis and frontotemporal lobar degeneration. Orthologs of TDP-43 exist in animals ranging from mammals to invertebrates. Here, we systematically studied mutant Caenorhabditis elegans lacking the nematode TDP-43 ortholog, TDP-1. Heterologous expression of human TDP-43 rescued the defects in C. elegans lacking TDP-1, suggesting their functions are conserved. Although the tdp-1 mutants exhibited deficits in fertility, growth, and locomotion, loss of tdp-1 attenuated defects in several C. elegans models of proteotoxicity. Loss of tdp-1 suppressed defects in transgenic C. elegans expressing TDP-43 or CuZn superoxide dismutase, both of which are associated with proteotoxicity in neurodegenerative diseases. Loss of tdp-1 also reduced defects in mutant animals lacking the heat shock factor HSF-1. Transcriptional profiling demonstrated that the loss of TDP-1 altered expression of genes functioning in RNA processing and protein folding. Furthermore, the absence of tdp-1 extended the life span in C. elegans. The life span extension required a FOXO transcriptional factor DAF-16 but not HSF-1. These results suggest that the C. elegans TDP-1 has a role in the regulation of protein homeostasis and aging.

Characterization of a novel Xenopus tropicalis cell line as a model for in vitro studies

Cell lines are useful tools to facilitate in vitro studies of many biological and molecular processes. We describe a new permanent fibroblast-type cell line obtained from disaggregated Xenopus tropicalis limb bud. The cell line population doubling time was ∼ 24 h. Its karyotype was genetically stable with a chromosome number of 2n = 21 and a chromosome 10 trisomy. These cells could be readily transfected and expressed transgenes faithfully. We obtained stable transformants using transposon-based gene transfer technology. These cells responded to thyroid hormone and thus can provide a complementary research tool to study thyroid hormone signaling events. In conclusion, this cell line baptized “Speedy” should prove useful to couple in vitro and in vivo biological studies in the X. tropicalisfrog model. genesis 50:316–324, 2012. © 2011 Wiley Periodicals, Inc.

Fermi surface and superconductivity in low-density high-mobility δ-doped SrTiO3

The electronic structure of low-density n-type SrTiO3 δ-doped heterostructures is investigated by angular dependent Shubnikov-de Haas oscillations. In addition to a controllable crossover from a three- to two-dimensional Fermi surface, clear beating patterns for decreasing dopant layer thicknesses are found. These indicate the lifting of the degeneracy of the conduction band due to subband quantization in the two-dimensional limit. Analysis of the temperature-dependent oscillations shows that similar effective masses are found for all components, associated with the splitting of the light electron pocket. The dimensionality crossover in the superconducting state is found to be distinct from the normal state, resulting in a rich phase diagram as a function of dopant layer thickness.

Common origin of the circular-dichroism pattern in angle-resolved photoemission spectroscopy of SrTiO3 and Cu(x)Bi2Se3

Circular dichroism in the angular distribution of photoelectrons from SrTiO(3):Nb and Cu(x)Bi(2)Se(3) is investigated by 7-eV laser angle-resolved photoemission spectroscopy. In addition to the well-known node that occurs in the circular dichroism pattern when the incidence plane matches the mirror plane of the crystal, we show that another type of node occurs when the mirror plane of the crystal is vertical to the incidence plane and the electronic state is two-dimensional. The flower-shaped circular dichroism patterns in the angular distribution occurring around the Fermi level of SrTiO(3):Nb and around the Dirac point of Cu(x)Bi(2)Se(3) are explained on equal footings. We point out that the penetration depth of the topological states of Cu(x)Bi(2)Se(3) depends on momentum.

Microscopic origins for stabilizing room-temperature ferromagnetism in ultrathin manganite layers

La(0.7)Sr(0.3)MnO(3) is a conducting ferromagnet at room temperature. Combined with thin SrTiO(3) layers, the resulting heterostructures could be used as highly spin-polarized magnetic-tunnel-junction memories. However, when shrunk to dimensions below an apparent critical thickness, the structures become insulating and ferromagnetic ordering is suppressed. Interface spin and charge modulations are thought to create an interfacial dead layer, thus fundamentally limiting the use of this material in atomic-scale devices. The thickness of this dead layer, and whether it is intrinsic, is still controversial. Here we use atomic-resolution electron spectroscopy to demonstrate that the degradation of the magnetic and transport properties of La(0.7)Sr(0.3)MnO(3)/SrTiO(3) multilayers correlates with atomic intermixing at the interfaces, and the presence of extended two-dimensional cation defects in the La(0.7)Sr(0.3)MnO(3) layers (in contrast to three-dimensional precipitates in thick films). When these extrinsic defects are eliminated, metallic ferromagnetism at room temperature can be stabilized in five-unit-cell-thick manganite layers in superlattices, placing the upper limit for any intrinsic dead layer at two unit cells per interface.

Two-dimensional confinement of 3d{1} electrons in LaTiO_{3}/LaAlO{3} multilayers

We report spectroscopic ellipsometry measurements of the anisotropy of the interband transitions parallel and perpendicular to the planes of (LaTiO3)n(LaAlO3)5 multilayers with n=1-3. These provide direct information about the electronic structure of the two-dimensional (2D) 3d{1} state of the Ti ions. In combination with local density approximation, including a Hubbard U calculation, we suggest that 2D confinement in the TiO2 slabs lifts the degeneracy of the t{2g} states leaving only the planar d{xy} orbitals occupied. We outline that these multilayers can serve as a model system for the study of the t{2g} 2D Hubbard model.

Dominant mobility modulation by the electric field effect at the LaAlO3/SrTiO3 interface

Caviglia et al. [Nature (London) 456, 624 (2008)] have found that the superconducting LaAlO3/SrTiO3 interface can be gate modulated. A central issue is to determine the principal effect of the applied electric field. Using magnetotransport studies of a gated structure, we find that the mobility variation is almost 5 times that of the sheet carrier density. Furthermore, superconductivity can be suppressed at both positive and negative gate bias. These results indicate that the relative disorder strength strongly increases across the superconductor-insulator transition.

Spectroscopic evidence for competing reconstructions in polar multilayers LaAlO3/LaVO3/LaAlO3

We have studied the valence redistribution of V in LaAlO(3)/LaVO(3)/LaAlO(3) trilayers, which are composed of only polar layers grown on SrTiO3 (001) substrates, by core-level photoemission spectroscopy. We have found that the V valence is intermediate between V3+ and V4+ for thin LaAlO3 cap layers, decreases with increasing cap-layer thickness, and finally recovers the bulk value of V3+ at approximately 10 unit-cell thickness. In order to interpret these results, we propose that the atomic reconstruction of the polar LaAlO3 surface competes with the purely electronic V valence change so that the polar catastrophe is avoided at the cost of minimum energy.

Vanishing hall coefficient in the extreme quantum limit in photocarrier-doped SrTiO3

We explore the extreme quantum limit of photogenerated electrons in quantum paraelectric SrTiO3. This regime is distinct from conventional semiconductors, due to the large electron effective mass and large dielectric constant. At low temperature, the magnetoresistance and Hall resistivity saturate at a high magnetic field, deviating from conventional behavior. As a result, the Hall coefficient vanishes on the scale of the ratio of the Landau level splitting to the thermal energy, indicating the essential role of lowest Landau level occupancy, as limited by thermal broadening.

Polar discontinuity doping of the LaVO_{3}/SrTiO_{3} interface

We have investigated the transport properties of LaVO_{3}/SrTiO_{3} Mott-insulator-band-insulator heterointerfaces for various configurations. The (001)-oriented n-type VO_{2}/LaO/TiO_{2} polar discontinuity is conducting, exhibiting a LaVO3 thickness-dependent metal-insulator transition and low temperature anomalous Hall effect. The (001) p-type VO_{2}/SrO/TiO_{2} interface, formed by inserting a single layer of bulk metallic SrVO3 or SrO, drives the interface insulating. The (110) heterointerface is also insulating, indicating interface conduction arising from electronic reconstructions.

Nanometer scale electronic reconstruction at the interface between LaVO3 and LaVO4

Electrons at interfaces, driven to minimize their free energy, are distributed differently than in bulk. This can be dramatic at interfaces involving heterovalent compounds. Here we profile an abrupt interface between V 3d2 LaVO3 and V 3d0 LaVO4 using electron energy loss spectroscopy. Although no bulk phase of LaVOx with a V 3d1 configuration exists, we find a nanometer-wide region of V 3d1 at the LaVO3/LaVO4 interface, rather than a mixture of V 3d0 and V 3d2. The two-dimensional sheet of 3d1 electrons is a prototypical electronic reconstruction at an interface between competing ground states.

Standardization of 125I and 238Pu

A simple distance-variable detection table on which two detectors can be mounted and moved back and forth facing each other centred on a sample source has been constructed for photon-photon and alpha-photon coincidence counting for 125I and 238Pu, respectively. Two NaI(Tl) detectors were used for the standardization of 125I. A Si detector and an NaI(Tl) detector were employed for the standardization of 238Pu. The NaI(Tl) detectors have a very thin aluminium window for measuring low-energy photons from 125I and 238Pu while the Si-detector is a usable-in-air ion-implanted detector for alpha particles from 238Pu. A thin collodion film was used for 238Pu samples, whereas a thick polyester film was used for 125I samples to prevent 125I from leaking from the sample. The key comparison result of 125I showed good agreement, and the result of 238Pu was also compared with that of liquid scintillation counting.

A high-mobility electron gas at the LaAlO3/SrTiO3 heterointerface

Polarity discontinuities at the interfaces between different crystalline materials (heterointerfaces) can lead to nontrivial local atomic and electronic structure, owing to the presence of dangling bonds and incomplete atomic coordinations. These discontinuities often arise in naturally layered oxide structures, such as the superconducting copper oxides and ferroelectric titanates, as well as in artificial thin film oxide heterostructures such as manganite tunnel junctions. If polarity discontinuities can be atomically controlled, unusual charge states that are inaccessible in bulk materials could be realized. Here we have examined a model interface between two insulating perovskite oxides--LaAlO3 and SrTiO3--in which we control the termination layer at the interface on an atomic scale. In the simple ionic limit, this interface presents an extra half electron or hole per two-dimensional unit cell, depending on the structure of the interface. The hole-doped interface is found to be insulating, whereas the electron-doped interface is conducting, with extremely high carrier mobility exceeding 10,000 cm2 V(-1) s(-1). At low temperature, dramatic magnetoresistance oscillations periodic with the inverse magnetic field are observed, indicating quantum transport. These results present a broad opportunity to tailor low-dimensional charge states by atomically engineered oxide heteroepitaxy.

Caenorhabditis elegans early embryogenesis and vulval morphogenesis require chondroitin biosynthesis

Defects in glycosaminoglycan biosynthesis disrupt animal development and can cause human disease. So far much of the focus on glycosaminoglycans has been on heparan sulphate. Mutations in eight squashed vulva (sqv) genes in Caenorhabditis elegans cause defects in cytokinesis during embryogenesis and in vulval morphogenesis during postembryonic development. Seven of the eight sqv genes have been shown to control the biosynthesis of the glycosaminoglycans chondroitin and heparan sulphate. Here we present the molecular identification and characterization of the eighth gene, sqv-5. This gene encodes a bifunctional glycosyltransferase that is probably localized to the Golgi apparatus and is responsible for the biosynthesis of chondroitin but not heparan sulphate. Our findings show that chondroitin is crucial for both cytokinesis and morphogenesis during C. elegans development.

The Caenorhabditis elegans genes sqv-2 and sqv-6, which are required for vulval morphogenesis, encode glycosaminoglycan galactosyltransferase II and xylosyltransferase

In mutants defective in any of eight Caenorhabditis elegans sqv (squashed vulva) genes, the vulval extracellular space fails to expand during vulval morphogenesis. Strong sqv mutations result in maternal-effect lethality, caused in part by the failure of the progeny of homozygous mutants to initiate cytokinesis and associated with the failure to form an extracellular space between the egg and the eggshell. Recent studies have implicated glycosaminoglycans in these processes. Here we report the cloning and characterization of sqv-2 and sqv-6. sqv-6 encodes a protein similar to human xylosyltransferases. Transfection of sqv-6 restored xylosyltransferase activity to and rescued the glycosaminoglycan biosynthesis defect of a xylosyltransferase mutant hamster cell line. sqv-2 encodes a protein similar to human galactosyltransferase II. A recombinant SQV-2 fusion protein had galactosyltransferase II activity with substrate specificity similar to that of human galactosyltransferase II. We conclude that C. elegans SQV-6 and SQV-2 likely act in concert with other SQV proteins to catalyze the stepwise formation of the proteoglycan core protein linkage tetrasaccharide GlcAbeta1,3Galbeta1, 3Galbeta1,4Xylbeta-O-(Ser), which is common to the two major types of glycosaminoglycans in vertebrates, chondroitin and heparan sulfate. Our results strongly support a model in which C. elegans vulval morphogenesis and zygotic cytokinesis depend on the expression of glycosaminoglycans.

Portal vein aneurysm of the umbilical portion: imaging features and the relationship with portal vein anomalies

BACKGROUND

We evaluated the imaging features of portal vein aneurysm occurring at the umbilical portion and the relation between portal vein aneurysm of the umbilical portion and portal vein anomaly.

METHODS

Retrograde analysis was performed in 18 patients with portal vein aneurysm of the umbilical portion of the portal vein. We analyzed the size, shape, and imaging findings of portal vein aneurysm. In addition, we evaluated associated portal vein anomalies, specifically, the branching pattern of the intrahepatic portal vein and the position of the umbilical portion of the left portal vein.

RESULTS

The diameter of the portal vein aneurysm ranged from 1.5 to 2.2 cm and the shape of the portal vein aneurysm was saccular (n = 14) or fusiform (n = 4). Imaging findings of the portal vein aneurysm of the umbilical portion were typical for its vascular nature. Portal vein anomalies were seen in eight of 18 patients (44%): the right anterior segmental portal vein (n = 7) or the right anterior and posterior segmental portal veins (n = 1) originating from the umbilical portion of the left portal vein and a rightward deviation of the umbilical portion of the left portal vein (n = 4).

CONCLUSION

Due to its vascular nature, noninvasive diagnostic modalities can enable the detection of portal vein aneurysm of the umbilical portion, and there is a close relation between portal vein aneurysm of the umbilical portion and portal vein anomaly.

The SQV-1 UDP-glucuronic acid decarboxylase and the SQV-7 nucleotide-sugar transporter may act in the Golgi apparatus to affect Caenorhabditis elegans vulval morphogenesis and embryonic development

Recent findings indicate that glycosaminoglycans can play important roles in animal development. The genes sqv-3, -7, and -8, which are necessary for vulval morphogenesis in Caenorhabditis elegans, affect the biosynthesis of chondroitin and heparan sulfate glycosaminoglycans. We cloned sqv-1 and showed that the SQV-1 protein is a type II transmembrane protein that functions as a UDP-glucuronic acid decarboxylase. SQV-1 localizes to punctate cytoplasmic compartments and colocalizes with the SQV-7 nucleotide-sugar transporter, which probably acts in the Golgi apparatus. SQV-1 and SQV-7 are both expressed in the vulva and in oocytes, where they likely act in vulval morphogenesis and embryonic development, respectively. Progeny of sqv-7 and sqv-1 null mutants fail to initiate cytokinesis, possibly because they are unable to separate the plasma membrane from the eggshell, a defect analogous to that of incomplete vulval invagination.

The Caenorhabditis elegans vulval morphogenesis gene sqv-4 encodes a UDP-glucose dehydrogenase that is temporally and spatially regulated

The development of the Caenorhabditis elegans vulva requires the involution of epithelial cells and provides a model for organ morphogenesis. Mutations in C. elegans sqv (squashed vulva) genes affect both vulval morphogenesis and embryonic development. We found that sqv-4 encodes a protein similar to UDP-glucose dehydrogenases and showed that the SQV-4 protein specifically catalyzes the conversion of UDP-glucose to UDP-glucuronic acid, which is essential for the biosynthesis of chondroitin and heparan sulfate proteoglycans. SQV-4 is expressed in the vulva and in oocytes, among many other cells, and SQV-4 levels are dramatically increased in a specific subset of vulval cells during vulval morphogenesis. We propose that the regulation of UDP-glucuronic acid production in a specific subset of vulval cells helps determine the shape of the vulva.

Artificial charge-modulationin atomic-scale perovskite titanate superlattices

The nature and length scales of charge screening in complex oxides are fundamental to a wide range of systems, spanning ceramic voltage-dependent resistors (varistors), oxide tunnel junctions and charge ordering in mixed-valence compounds. There are wide variations in the degree of charge disproportionation, length scale, and orientation in the mixed-valence compounds: these have been the subject of intense theoretical study, but little is known about the microscopic electronic structure. Here we have fabricated an idealized structure to examine these issues by growing atomically abrupt layers of LaTi(3+)O(3) embedded in SrTi(4+)O(3). Using an atomic-scale electron beam, we have observed the spatial distribution of the extra electron on the titanium sites. This distribution results in metallic conductivity, even though the superlattice structure is based on two insulators. Despite the chemical abruptness of the interfaces, we find that a minimum thickness of five LaTiO(3) layers is required for the centre titanium site to recover bulk-like electronic properties. This represents a framework within which the short-length-scale electronic response can be probed and incorporated in thin-film oxide heterostructures.

Strong self-phase modulation in planar chalcogenide glass waveguides

Single-mode planar waveguides were fabricated from chalcogenide glass compounds with large Kerr nonlinearities. Strong self-phase modulation of subpicosecond pulses along with low linear and nonlinear absorption losses demonstrates the potential for ultrafast, low-power, all-optical processing applications.

Development of MCTS technique for 3-PM liquid scintillation counting

We have developed a multi-channel time scaling method that is suitable for activity measurement of beta emitting nuclides by means of 3-PM Liquid Scintillation Counting, using non-extending dead times and linear amplifiers. Since it enables to obtain the accidental coincidences directly, the true values for both double and triple coincidences are determined by simply taking into account the correction due to dead times. The advantages of the method are demonstrated by studying the activity of 204Tl and 14C. The measured results were compared with those derived by using the mathematical formulae.

Comparison of tuberculous and pyogenic epididymal abscesses: clinical, gray-scale sonographic, and color Doppler sonographic features

OBJECTIVE

The purpose of this study was to evaluate the capability of clinical, gray-scale sonographic, and color Doppler sonographic features for differentiating tuberculous and pyogenic epididymal abscesses.

MATERIALS AND METHODS

Retrospective analysis was performed in 10 cases of tuberculous epididymal abscess and in 13 cases of pyogenic epididymal abscess. The following clinical, gray-scale sonographic, and color Doppler sonographic features were analyzed: patient's age; duration of symptoms; scrotal tenderness; presence of sinus tract; concurrent tuberculosis in other organs; location, size, and echogenicity of the abscess; hyperechoic rim; testicular involvement; hydrocele; and blood flow in the epididymal lesion.

RESULTS

Tuberculous epididymal abscess had a longer duration of symptoms (p = 0.0001) and a lower frequency of scrotal tenderness (p = 0.0048) than pyogenic epididymal abscess. The size of the abscess was larger in tuberculous epididymal abscess than in pyogenic epididymal abscess (p = 0.0002). The degree of blood flow in the peripheral portion of the abscess was lower in tuberculous epididymal abscess (p = 0.001). The patient's age, location and echogeninicity of the abscess, presence of sinus tract, hyperechoic rim, testicular involvement, and hydrocele did not differ between the tuberculous and pyogenic epididymal abscesses.

CONCLUSION

Some clinical findings, gray-scale sonography, and color Doppler sonography were useful in differentiating tuberculous epididymal abscess from pyogenic epididymal abscess. The presence of long-term scrotal swelling without tenderness and a lower degree of blood flow in the peripheral portion of a large abscess are suggestive of tuberculous epididymal abscess.

Effect of hormone replacement therapy on nitric oxide bioactivity and monocyte chemoattractant protein-1 levels

BACKGROUND

Vascular inflammation plays an important role in the pathogenesis of atherosclerosis. We investigated the effect of hormone replacement therapy (HRT) on vasomotor function and monocyte chemoattractant protein (MCP)-1 levels, an important serological marker of inflammation.

METHODS

We administered micronized progesterone (MP) 200 mg for 10 days with conjugated equine estrogen (CEE) 0.625 mg for 25 days and remaining 5 days off cyclically during 2 months to 20 healthy postmenopausal women (PMW). We measured NO bioactivity and plasma levels of MCP-1 before and after HRT in 20 PMW. And we measured plasma levels of MCP-1 in each 20 subjects of premenopausal women, men <50, and men >50 years, respectively.

RESULTS

MP combined with CEE significantly improved the percent flow-mediated dilator response to hyperemia relative to baseline measurements (P<0.001). PMW receiving HRT had lower levels of MCP-1 than those not receiving HRT (121+/-38 versus 146+/-44 pg/ml, P<0.001). In all comparisons, subjects with high estrogen status had significantly lower MCP-1 levels than subjects with low estrogen status (P<0.001 by ANOVA). Premenopausal women had lower levels of MCP-1 than men of a similar age (106+/-14 versus 164+/-40 pg/ml, P<0.001). PMW not receiving HRT had similar levels of MCP-1 compared with men of a similar age (146+/-44 versus 143+/-29 pg/ml, P=0.816). Premenopausal women had markedly lower levels of MCP-1 than PMW not receiving HRT (106+/-14 versus 146+/-44 pg/ml, P=0.001). PMW receiving HRT had similar levels of MCP-1 compared with premenopausal women (121+/-38 versus 106+/-14 pg/ml, P=0.323).

CONCLUSION

These findings might provide at least a partial explanation for the protection against cardiovascular disease experienced by premenopausal women, and the loss of that protection following menopause.

Vascular effects of estrogen in type II diabetic postmenopausal women

OBJECTIVES

We assessed the effects of estrogen on vascular dilatory and other homeostatic functions potentially affected by nitric oxide (NO)-potentiating properties in type II diabetic postmenopausal women.

BACKGROUND

There is a higher cardiovascular risk in diabetic women than in nondiabetic women. This would suggest that women with diabetes do not have the cardioprotection associated with estrogen.

METHODS

We administered placebo or conjugated equine estrogen, 0.625 mg/day for 8 weeks, to 20 type II diabetic postmenopausal women in a randomized, double-blinded, placebo-controlled, cross-over design.

RESULTS

Compared with placebo, estrogen tended to lower low-density lipoprotein (LDL) cholesterol levels by 15 +/- 23% (p = 0.007) and increase high-density lipoprotein (HDL) cholesterol levels by 8 +/- 16% (p = 0.034). Thus, the ratio of LDL to HDL cholesterol levels significantly decreased with estrogen, by 20 +/- 24%, as compared with placebo (p = 0.001). Compared with placebo, estrogen tended to increase triglyceride levels by 16 +/- 48% and lower glycosylated hemoglobin levels by 3 +/- 13% (p = 0.295 and p = 0.199, respectively). However, estrogen did not significantly improve the percent flow-mediated dilatory response to hyperemia (17 +/- 75% vs. placebo; p = 0.501). The statistical power to accept our observation was 81.5%. Compared with placebo, estrogen did not significantly change E-selectin, intercellular adhesion molecule-1, vascular cell adhesion molecule-1, monocyte chemoattractant protein-1 or matrix metalloproteinase-9 levels. Compared with placebo, estrogen tended to decrease tissue factor antigen and increase tissue factor activity levels by 7 +/- 46% and 5 +/- 34%, respectively (p = 0.321 and p = 0.117, respectively) and lower plasminogen activator inhibitor-1 levels by 16 +/- 31% (p = 0.043).

CONCLUSIONS

The effects of estrogen on endothelial, vascular dilatory and other homeostatic functions were less apparent in type II diabetic postmenopausal women, despite the beneficial effects of estrogen on lipoprotein levels.

Neonatal intensive care unit outbreak caused by a strain of Klebsiella oxytoca resistant to aztreonam due to overproduction of chromosomal beta-lactamase

Klebsiella oxytoca strains resistant to both aztreonam and ceftriaxone were isolated from six neonates in a neonatal intensive care unit and water reservoirs of two humidifiers attached to the neonatal incubators. These isolates were assumed to be of the same clone because they were characterized by the same antimicrobial susceptibility and pulsed field gel electrophoresis patterns. It was established that the drug resistance was attributed to overproduction of chromosomally encoded Kl beta-lactamase. It was determined that an isolate (K. oxytoca H1) contained a high enzyme concentration (27microg/100microg of protein in enzyme extracts), at least 27 times higher than the control K. oxytoca N1. It was also demonstrated that isolates had a point mutation in the - 35 concensus region of the promotor gene of bla(OXY-2)leading to enzyme overproduction. Outbreaks caused by K1 hyperproducers have not previously been described.

CT findings of portal vein aneurysm caused by gastric adenocarcinoma invading the portal vein

The known causes of acquired origin portal vein aneurysm are portal hypertension, pancreatitis and trauma. We describe the CT findings of an additional cause of acquired origin portal vein aneurysm, namely gastric adenocarcinoma invading the portal venous system.

Expression of recombinant human granulocyte macrophage-colony stimulating factor (hGM-CSF) in mouse urine

We have generated transgenic mice expressing human granulocyte macrophage-colony stimulating factor (hGM-CSF) in urine. In particular, the expression plasmid DNA containing mouse uroplakin II promoter was used to direct uroepithelium-specific transcription of transgene. In this study, hGM-CSF transcript was detected only in bladder uroepithelium as determined by northern blot analysis. Furthermore, hGM-CSF protein was detected in the suprabasal layer of the uroepithelium and ureter by immunohistochemistry. The hGM-CSF was secreted into urine at high level (up to 180 ng/ml), and enhanced proliferation of hGM-CSF-dependent human acute monocyte leukemic cells, suggesting that transgenic urine-derived hGM-CSF was bioactive. This is the first case of demonstrating biological activity of a cytokine produced in the urine of a transgenic animal. Our results demonstrate that bladder can be used as a bioreactor to produce biologically important substances. In addition, it suggests a potential application of bladder expression system to livestock for high-yield production of pharmaceuticals.

Vascular effects of synthetic or natural progestagen combined with conjugated equine estrogen in healthy postmenopausal women

BACKGROUND

Synthetic, not natural, progestagen may negate the favorable effects of estrogen. Nonetheless, observational studies report no differences in risk for clinical cardiovascular events between users of unopposed estrogen and users of estrogen combined with synthetic progestin.

METHODS AND RESULTS

In a double-blind study, we randomly assigned 20 healthy postmenopausal women to micronized progesterone (MP) 200 mg or medroxyprogesterone acetate (MPA) 10 mg for 10 days with conjugated equine estrogen (CEE) 0.625 mg for 25 days and the remaining 5 days off cyclically during 2 months, followed by crossover to the alternate therapy. CEE+MP and CEE+MPA significantly improved the percent flow-mediated dilator response to hyperemia relative to baseline measurements (P=0.004 by ANOVA) by a similar degree (P=0.863). Both therapies significantly decreased E-selectin, intercellular adhesion molecule (ICAM)-1, and vascular cell adhesion molecule (VCAM)-1 levels from baseline values (P<0.001, P=0.048, and P=0.016 by ANOVA, respectively) by a similar degree (P=0.977 for ICAM-1 and P=0.541 for VCAM-1, respectively). CEE+MPA decreased E-selectin levels more than CEE+MP did (P=0.040). Both therapies significantly decreased monocyte chemoattractant protein-1 levels from baseline values (P<0.005 by ANOVA) by a similar degree (P=0.194). Both therapies significantly decreased tissue factor antigen and increased tissue factor activity levels from baseline values (P=0.003 and P<0.001 by ANOVA, respectively) by a similar degree (P=0.652 for antigen and P=0.173 for activity). Both therapies significantly lowered plasma plasminogen activator inhibitor-1 levels from baseline values (P<0.001 by ANOVA) by a similar degree (P=0.533).

CONCLUSIONS

CEE+MP and CEE+MPA provide similar improvement in endothelium-dependent vasodilator responsiveness and effects on markers of inflammation, hemostasis, and fibrinolysis inhibition in healthy postmenopausal women.

Josephson junctions with tunable weak links

The electrical properties of organic molecular crystals, such as polyacenes or C60, can be tuned from insulating to superconducting by application of an electric field. By structuring the gate electrode of such a field-effect switch, the charge carrier density, and therefore also the superfluid density, can be modulated. Hence, weak links that behave like Josephson junctions can be fabricated between two superconducting regions. The coupling between the superconducting regions can be tuned and controlled over a wide range by the applied gate bias. Such devices might be used in superconducting circuits, and they are a useful scientific tool to study superconducting material parameters, such as the superconducting gap, as a function of carrier concentration or transition temperature.