Dynamics of magnetization at infinite temperature in a Heisenberg spin chain

Understanding universal aspects of quantum dynamics is an unresolved problem in statistical mechanics. In particular, the spin dynamics of the one-dimensional Heisenberg model were conjectured as to belong to the Kardar-Parisi-Zhang (KPZ) universality class based on the scaling of the infinite-temperature spin-spin correlation function. In a chain of 46 superconducting qubits, we studied the probability distribution of the magnetization transferred across the chain's center, [Formula: see text]. The first two moments of [Formula: see text] show superdiffusive behavior, a hallmark of KPZ universality. However, the third and fourth moments ruled out the KPZ conjecture and allow for evaluating other theories. Our results highlight the importance of studying higher moments in determining dynamic universality classes and provide insights into universal behavior in quantum systems.

Stable quantum-correlated many-body states through engineered dissipation

Engineered dissipative reservoirs have the potential to steer many-body quantum systems toward correlated steady states useful for quantum simulation of high-temperature superconductivity or quantum magnetism. Using up to 49 superconducting qubits, we prepared low-energy states of the transverse-field Ising model through coupling to dissipative auxiliary qubits. In one dimension, we observed long-range quantum correlations and a ground-state fidelity of 0.86 for 18 qubits at the critical point. In two dimensions, we found mutual information that extends beyond nearest neighbors. Lastly, by coupling the system to auxiliaries emulating reservoirs with different chemical potentials, we explored transport in the quantum Heisenberg model. Our results establish engineered dissipation as a scalable alternative to unitary evolution for preparing entangled many-body states on noisy quantum processors.

Measurement-induced entanglement and teleportation on a noisy quantum processor

Measurement has a special role in quantum theory1: by collapsing the wavefunction, it can enable phenomena such as teleportation2 and thereby alter the 'arrow of time' that constrains unitary evolution. When integrated in many-body dynamics, measurements can lead to emergent patterns of quantum information in space-time3-10 that go beyond the established paradigms for characterizing phases, either in or out of equilibrium11-13. For present-day noisy intermediate-scale quantum (NISQ) processors14, the experimental realization of such physics can be problematic because of hardware limitations and the stochastic nature of quantum measurement. Here we address these experimental challenges and study measurement-induced quantum information phases on up to 70 superconducting qubits. By leveraging the interchangeability of space and time, we use a duality mapping9,15-17 to avoid mid-circuit measurement and access different manifestations of the underlying phases, from entanglement scaling3,4 to measurement-induced teleportation18. We obtain finite-sized signatures of a phase transition with a decoding protocol that correlates the experimental measurement with classical simulation data. The phases display remarkably different sensitivity to noise, and we use this disparity to turn an inherent hardware limitation into a useful diagnostic. Our work demonstrates an approach to realizing measurement-induced physics at scales that are at the limits of current NISQ processors.

Non-Abelian braiding of graph vertices in a superconducting processor

Indistinguishability of particles is a fundamental principle of quantum mechanics¹. For all elementary and quasiparticles observed to date-including fermions, bosons and Abelian anyons-this principle guarantees that the braiding of identical particles leaves the system unchanged^2,3. However, in two spatial dimensions, an intriguing possibility exists: braiding of non-Abelian anyons causes rotations in a space of topologically degenerate wavefunctions^4-8. Hence, it can change the observables of the system without violating the principle of indistinguishability. Despite the well-developed mathematical description of non-Abelian anyons and numerous theoretical proposals^9-22, the experimental observation of their exchange statistics has remained elusive for decades. Controllable many-body quantum states generated on quantum processors offer another path for exploring these fundamental phenomena. Whereas efforts on conventional solid-state platforms typically involve Hamiltonian dynamics of quasiparticles, superconducting quantum processors allow for directly manipulating the many-body wavefunction by means of unitary gates. Building on predictions that stabilizer codes can host projective non-Abelian Ising anyons^9,10, we implement a generalized stabilizer code and unitary protocol²³ to create and braid them. This allows us to experimentally verify the fusion rules of the anyons and braid them to realize their statistics. We then study the prospect of using the anyons for quantum computation and use braiding to create an entangled state of anyons encoding three logical qubits. Our work provides new insights about non-Abelian braiding and, through the future inclusion of error correction to achieve topological protection, could open a path towards fault-tolerant quantum computing.

Formation of robust bound states of interacting microwave photons

Systems of correlated particles appear in many fields of modern science and represent some of the most intractable computational problems in nature. The computational challenge in these systems arises when interactions become comparable to other energy scales, which makes the state of each particle depend on all other particles1. The lack of general solutions for the three-body problem and acceptable theory for strongly correlated electrons shows that our understanding of correlated systems fades when the particle number or the interaction strength increases. One of the hallmarks of interacting systems is the formation of multiparticle bound states2-9. Here we develop a high-fidelity parameterizable fSim gate and implement the periodic quantum circuit of the spin-½ XXZ model in a ring of 24 superconducting qubits. We study the propagation of these excitations and observe their bound nature for up to five photons. We devise a phase-sensitive method for constructing the few-body spectrum of the bound states and extract their pseudo-charge by introducing a synthetic flux. By introducing interactions between the ring and additional qubits, we observe an unexpected resilience of the bound states to integrability breaking. This finding goes against the idea that bound states in non-integrable systems are unstable when their energies overlap with the continuum spectrum. Our work provides experimental evidence for bound states of interacting photons and discovers their stability beyond the integrability limit.

Noise-resilient edge modes on a chain of superconducting qubits

Inherent symmetry of a quantum system may protect its otherwise fragile states. Leveraging such protection requires testing its robustness against uncontrolled environmental interactions. Using 47 superconducting qubits, we implement the one-dimensional kicked Ising model, which exhibits nonlocal Majorana edge modes (MEMs) with ℤ 2 parity symmetry. We find that any multiqubit Pauli operator overlapping with the MEMs exhibits a uniform late-time decay rate comparable to single-qubit relaxation rates, irrespective of its size or composition. This characteristic allows us to accurately reconstruct the exponentially localized spatial profiles of the MEMs. Furthermore, the MEMs are found to be resilient against certain symmetry-breaking noise owing to a prethermalization mechanism. Our work elucidates the complex interplay between noise and symmetry-protected edge modes in a solid-state environment.

Impacts of slurry application methods and inhibitors on gaseous emissions and N2O pathways in meadow-cinnamon soil

This study aimed to evaluate the impact of mitigation practices (slurry application methods and inhibitors applications) on gas emissions and identify the soil N₂O production pathways in cattle slurry applied soil using isotopocule mapping approach. First, we compared the NH₃ and N₂O emissions of cattle slurry applied soil in a summer maize field experiment in north China plain (NCP) with four treatments: control (CK, no fertilization), slurry application using surface (SA-S), slurry application using band application (BA-S), and chemical fertilizer application using band application (BA-C). Then, an incubation experiment was conducted to investigate the mitigation effect of nitrification inhibitors (dicyandiamide, DCD) and denitrification inhibitors (procyanidins, PC) and their combination (DCD + PC) on gaseous N emissions with slurry applied using incorporation (IA) or surface application (SA) methods. The results showed that the total gaseous N emissions (N₂O-N and NH₃-N) in field were in the order of SA-S (1534 mg m^-2) > BA-S (338 mg m^-2) > BA-C (128 mg m^-2) > CK (55 mg m^-2), and the dominant N loss contributor varied from NH₃ in SA-S (∼89%) to N₂O in BA-S (∼94%) and BA-C (∼88%). Moreover, the isotopocule mapping approach indicated that emitted N₂O of the slurry applied soil in field appeared to have lower r_N2O values and led to more N₂O + N₂ emissions at the initial fertilization period. The incubation experiment indicated that the N₂O emissions of slurry-applied soil were significantly reduced by DCD (∼45%) and DCD + PC (∼67%) application in comparison with CK (p < 0.05), and the stronger contributions of bacterial denitrification/nitrifier denitrification to N₂O production were revealed by the lower δ¹⁵N^SP in N₂O using the isotopocule mapping approach. In conclusion, in NCP the gaseous losses of the slurry applied field can be largely reduced by using incorporation method, and greater reduction could be achieved given the simultaneous application of nitrification/denitrification inhibitors.

Realizing topologically ordered states on a quantum processor

[Figure: see text].

Comparative study of the distribution and expression of Neuroglobin and Hypoxia-inducible factor-1α in the adult and young Yak Brain

BACKGROUND

The brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals.

AIM

The study examined the expression of Neuroglobin (Ngb) and Hypoxia-inducible factor-1α (Hif-1α) in adult and young yak brain tissues, and provided researchers with meaningful insight into the anatomy, physiology, and biochemistry of this mammal.

METHOD

The study employed immunohistochemistry (IHC), quantitative real-time PCR (qRT-PCR), and Western blot (WB) to obtain the results.

RESULTS

Ngb and Hif-1α were significantly (P<0.05) expressed in the cerebellar cortex, piriform lobe, medulla, and corpus callosum of the adult yak while in the young yak brain tissues, the protein expressions were significantly found in the white matter of the cerebellum, pineal gland, corpus callosum, and cerebellar cortex. The Ngb and Hif-1α expression showed similarities and differences. This may have resulted from similar animal species, source of nutrition, age factors, brain size, emotional activities, and communication. The findings documented that Ngb and Hif-1α are commonly expressed in various adult and young yak brain tissues. Multiple roles in the brain tissues of the adult and young yaks are involved in the expression and distribution and are proposed to play a significant role in the adaptation of the yak to the high altitude environment.

CONCLUSION

This study provides meaningful data to understand the adaptive mechanism to hypoxia and recommended researchers to expand on the adaptive mechanism and brain tissues that are not recorded.

Comparative study on the distribution and expression of Neuroglobin and Hypoxia-inducible factor-1α in the telencephalon of yak and cattle

The telencephalon refers to the most highly developed and anterior part of the forebrain, consisting mainly of the cerebral hemispheres. The study determined Neuroglobin (Ngb) and Hypoxia-inducible factor (HIF-1α) expression in the telencephalon of yak and cattle, and compare the expression and distribution pattern of Ngb and HIF-1α in the two animals. Immunohistochemistry (IHC), quantitative real-time Polymerase Chain Reaction (qRT-PCR), and Western blot (WB) were employed to investigate Ngb and Hif-1α expression in the telencephalon of yak and cattle. mRNA and protein expressions of Ngb and HIF-1α showed positive in different tissues of the yak and cattle telencephalon. Ngb expression in tissues of the yak recorded higher as compare to cattle while HIF-1α expression was found higher in cattle than yak. The HIF-1α expression in some tissues of yak telencephalon was consistent with the cattle. The results documented that HIF-1α may have a direct or indirect synergistic effect on Ngb expression in the yak telencephalon to improve hypoxia adaptation. It is suggested that yak may need more Ngb expression for adaptation, but the expression of HIF-1α seems to be down-regulated during long-term adaptation, and the specific causes of this phenomenon needs to be further verified.

Removing leakage-induced correlated errors in superconducting quantum error correction

Quantum computing can become scalable through error correction, but logical error rates only decrease with system size when physical errors are sufficiently uncorrelated. During computation, unused high energy levels of the qubits can become excited, creating leakage states that are long-lived and mobile. Particularly for superconducting transmon qubits, this leakage opens a path to errors that are correlated in space and time. Here, we report a reset protocol that returns a qubit to the ground state from all relevant higher level states. We test its performance with the bit-flip stabilizer code, a simplified version of the surface code for quantum error correction. We investigate the accumulation and dynamics of leakage during error correction. Using this protocol, we find lower rates of logical errors and an improved scaling and stability of error suppression with increasing qubit number. This demonstration provides a key step on the path towards scalable quantum computing.

Demonstrating a Continuous Set of Two-Qubit Gates for Near-Term Quantum Algorithms

Quantum algorithms offer a dramatic speedup for computational problems in material science and chemistry. However, any near-term realizations of these algorithms will need to be optimized to fit within the finite resources offered by existing noisy hardware. Here, taking advantage of the adjustable coupling of gmon qubits, we demonstrate a continuous two-qubit gate set that can provide a threefold reduction in circuit depth as compared to a standard decomposition. We implement two gate families: an imaginary swap-like (iSWAP-like) gate to attain an arbitrary swap angle, θ, and a controlled-phase gate that generates an arbitrary conditional phase, ϕ. Using one of each of these gates, we can perform an arbitrary two-qubit gate within the excitation-preserving subspace allowing for a complete implementation of the so-called Fermionic simulation (fSim) gate set. We benchmark the fidelity of the iSWAP-like and controlled-phase gate families as well as 525 other fSim gates spread evenly across the entire fSim(θ,ϕ) parameter space, achieving a purity-limited average two-qubit Pauli error of 3.8×10^{-3} per fSim gate.

miR-18a expression in basal cell carcinoma and regulatory mechanism on autophagy through mTOR pathway

BACKGROUND

Basal cell carcinoma (BCC) is the most common form of skin carcinoma.

AIM

To investigate the function of key micro(mi)RNAs and to explore the potential molecular mechanisms involved in BCC.

METHODS

The microarray dataset GSE34535, which comprises seven BCC samples and seven control samples, was downloaded from the Gene Expression Omnibus database. Differentially expressed miRNAs (DE-miRNAs) were identified. We collected tissue samples from 20 patients with BCC and 20 healthy controls (HCs), to compare the miR-18a expression in their tissue samples. Expression of miR-18a in A431 and HaCaT cells was also assayed. Following this, we upregulated and downregulated miR-18a expression in A431 cells to examine the effects on cell proliferation, migration and apoptosis. To further investigate the relative mechanism, the proteins LC3, Beclin 1, Akt and mammalian target of rapamycin (mTOR) were examined by quantitative real-time PCR and Western blotting. For further verification, we examined the expression of LC3 in the 20 BCC and 20 HC tissue samples.

RESULTS

In total, 19 DE-miRNAs (13 upregulated and 6 downregulated) that were common to the BCC and HC groups were identified. Levels of miR-18a were about three-fold higher in BCC tissues and A431 cells compared with their respective control groups. In vitro, downregulation of miR-18a was shown to inhibit cell proliferation and activate autophagy via the Akt/mTOR signalling pathway, while upregulation of miR-18a promoted proliferation of these cells. LC3 was decreased in BCC compared with HC tissue samples.

CONCLUSIONS

Our data support an oncogenic role of miR-18a through a novel Akt/mTOR/Beclin 1/LC3 axis, and suggest that the antitumour effects of miR-18a inhibitor may make it suitable for BCC therapy.

Diabatic Gates for Frequency-Tunable Superconducting Qubits

We demonstrate diabatic two-qubit gates with Pauli error rates down to 4.3(2)×10^{-3} in as fast as 18 ns using frequency-tunable superconducting qubits. This is achieved by synchronizing the entangling parameters with minima in the leakage channel. The synchronization shows a landscape in gate parameter space that agrees with model predictions and facilitates robust tune-up. We test both iswap-like and cphase gates with cross-entropy benchmarking. The presented approach can be extended to multibody operations as well.

High-Resolution Valley Spectroscopy of Si Quantum Dots

We study an accumulation mode Si/SiGe double quantum dot (DQD) containing a single electron that is dipole coupled to microwave photons in a superconducting cavity. Measurements of the cavity transmission reveal dispersive features due to the DQD valley states in Si. The occupation of the valley states can be increased by raising the temperature or applying a finite source-drain bias across the DQD, resulting in an increased signal. Using the cavity input-output theory and a four-level model of the DQD, it is possible to efficiently extract valley splittings and the inter- and intravalley tunnel couplings.

Threshold Dynamics of a Semiconductor Single Atom Maser

We demonstrate a single atom maser consisting of a semiconductor double quantum dot (DQD) that is embedded in a high-quality-factor microwave cavity. A finite bias drives the DQD out of equilibrium, resulting in sequential single electron tunneling and masing. We develop a dynamic tuning protocol that allows us to controllably increase the time-averaged repumping rate of the DQD at a fixed level detuning, and quantitatively study the transition through the masing threshold. We further examine the crossover from incoherent to coherent emission by measuring the photon statistics across the masing transition. The observed threshold behavior is in agreement with an existing single atom maser theory when small corrections from lead emission are taken into account.

High-dose dexamethasone or all-trans-retinoic acid restores the balance of macrophages towards M2 in immune thrombocytopenia

Essentials M1/M2 imbalance is involved in many autoimmune diseases, and could be restored. The expressions and functions of M1 and M2 were investigated in an in vitro culture system. A preferred M1 polarization is involved in the pathogenesis of immune thrombocytopenia (ITP). High-dose dexamethasone or all-trans-retinoic acid restores M1/M2 balance in ITP patients.

SUMMARY

Background Immune thrombocytopenia (ITP) is an autoimmune disorder. Deficiency of immune tolerance in antigen-presenting cells and cross-communication between antigen-presenting cells and T cells are involved in the pathogenesis of ITP. Macrophages can polarize into proinflammatory M1 or anti-inflammatory M2 phenotypes in response to different environmental stimuli, and have diverse immunologic functions. Objectives To investigate the M1/M2 imbalance in ITP and whether high-dose dexamethasone (HD-DXM) or all-trans-retinoic acid (ATRA) could restore this imbalance. Methods The numbers of M1 and M2 macrophages in the spleens of ITP patients and patients with traumatic spleen rupture were analyzed by immunofluorescence. Monocyte-derived macrophages were cultured and induced with cytokines and drugs. The expression of M1 and M2 markers and functions of M1 and M2 macrophages before and after modulation by HD-DXM or ATRA were evaluated with flow cytometry and ELISA. Results There was preferred M1 polarization in ITP spleens as compared with healthy controls. Monocyte-derived macrophages from ITP patients had increased expression of M1 markers and impaired immunosuppressive functions. Either HD-DXM or ATRA corrected this imbalance by decreasing the expression of M1 markers and increasing the expression of M2 markers. Moreover, HD-DXM-modulated or ATRA-modulated macrophages suppressed both CD4+ and CD8+ T-cell proliferation and expanded CD4+ CD49+ LAG3+ type 1 T-regulatory cells. HD-DXM or ATRA modulated macrophages to shift the T-cell cytokine profile towards Th2. Treating patients with HD-DXM or ATRA revealed that macrophages induced from responders showed a predominant M2-like phenotype and immunosuppressive function. Conclusions Aberrant macrophage polarization is involved in the pathogenesis of ITP. Either HD-DXM or ATRA is able to correct this imbalance.

Effects of JIP3 on epileptic seizures: Evidence from temporal lobe epilepsy patients, kainic-induced acute seizures and pentylenetetrazole-induced kindled seizures

JNK-interacting protein 3 (JIP3), also known as JNK stress-activated protein kinase-associated protein 1 (JSAP1), is a scaffold protein mainly involved in the regulation of the pro-apoptotic signaling cascade mediated by c-Jun N-terminal kinase (JNK). Overexpression of JIP3 in neurons in vitro has been reported to lead to accelerated activation of JNK and enhanced apoptosis response to cellular stress. However, the occurrence and the functional significance of stress-induced modulations of JIP3 levels in vivo remain elusive. In this study, we investigated the expression of JIP3 in temporal lobe epilepsy (TLE) and in a kainic acid (KA)-induced mouse model of epileptic seizures, and determined whether down-regulation of JIP3 can decrease susceptibility to seizures and neuron damage induced by KA. We found that JIP3 was markedly increased in TLE patients and a mouse model of epileptic seizures; mice underexpressing JIP3 through lentivirus bearing LV-Letm1-RNAi showed decreased susceptibility, delayed first seizure and decreased seizure duration response to the epileptogenic properties of KA. Subsequently, a decreased activation of JNK following seizure induction was observed in mice underexpressing JIP3, which also exhibited less neuronal apoptosis in the CA3 region of the hippocampus, as assessed three days after KA administration. We also found that mice underexpressing JIP3 exhibited a delayed pentylenetetrazole (PTZ)-induced kindling seizure process.

Minocycline inhibits brain inflammation and attenuates spontaneous recurrent seizures following pilocarpine-induced status epilepticus

Mounting evidence suggests that brain inflammation mediated by glial cells may contribute to epileptogenesis. Minocycline is a second-generation tetracycline and has potent antiinflammatory effects independent of its antimicrobial action. The present study aimed to investigate whether minocycline could exert antiepileptogenic effects in a rat lithium-pilocarpine model of temporal lobe epilepsy. The temporal patterns of microglial and astrocytic activation were examined in the hippocampal CA1 and the adjacent cortex following pilocarpine-induced status epilepticus (SE). These findings displayed that SE caused acute and persistent activation of microglia and astrocytes. Based on these findings, Minocycline was administered once daily at 45 mg/kg for 14 days following SE. Six weeks after termination of minocycline treatment, spontaneous recurrent seizures (SRS) were recorded by continuous video monitoring. Minocycline inhibited the SE-induced microglial activation and the increased production of interleukin-1β and tumor necrosis factor-α in the hippocampal CA1 and the adjacent cortex, without affecting astrocytic activation. In addition, Minocycline prevented the SE-induced neuronal loss in the brain regions examined. Moreover, minocycline significantly reduced the frequency, duration, and severity of SRS during the two weeks monitoring period. These results demonstrated that minocycline could mitigate SE-induced brain inflammation and might exert disease-modifying effects in an animal model of temporal lobe epilepsy. These findings offer new insights into deciphering the molecular mechanisms of epileptogenesis and exploring a novel therapeutic strategy for prevention of epilepsy.

Genome-wide transcriptional analysis of differentially expressed genes in flagellin-pretreated mouse corneal epithelial cells in response to Pseudomonas aeruginosa: involvement of S100A8/A9

We previously showed that pre-exposure of the cornea to Toll-like receptor 5 ligand flagellin induces profound mucosal innate protection against infections by modifying gene expression. Taking advantage of easily procurable epithelial cell population, this study is the first report to use genome-wide cDNA microarray approach to document genes associated with flagellin-induced protection against Pseudomonas aeruginosa in corneal epithelial cells (CECs). Infection altered the expression of 675 genes (497 up and 178 down), while flagellin pretreatment followed by infection resulted in a great increase in 890 gene upregulated and 37 genes downregulated. Comparing these two groups showed 209 differentially expressed genes (157 up, 52 down). Notably, among 114 genes categorized as defense related, S100A8/A9 are the two most highly induced genes by flagellin, and their expression in the corneal was confirmed by realtime PCR and immunohistochemistry. Neutralization of S100A8 and, to a less extent, A9, resulted in significantly increased bacterial burden and severe keratitis. Collectively, our study identifies many differentially expressed genes by flagellin in CECs in response to Pseudomonas. These novel gene expression signatures provide new insights and clues into the nature of protective mechanisms established by flagellin and new therapeutic targets for reducing inflammation and for controlling microbial infection.

Fine mapping of qhir1 influencing in vivo haploid induction in maize

Production of haploids by the in vivo haploid induction method has now become routine for generating new inbred lines in maize. In previous studies, a major quantitative trait locus (QTL) (qhir1) located in bin 1.04 was detected, explaining up to 66 % of the genotypic variance for haploid induction rate (HIR). Our objectives were to (1) fine-map qhir1 and (2) identify closely linked markers useful for marker-assisted breeding of new inducers. For this purpose, we screened a mapping population of 14,375 F2 plants produced from a cross between haploid inducer UH400 and non-inducer line 1680 to identify recombinants. Based on sequence information from the B73 reference genome, markers polymorphic between the two parents were developed to conduct fine mapping with these recombinants. A progeny test mapping strategy was applied to accurately determine the HIR of the 14 recombinants identified. Furthermore, F3 progeny of recombinant F2 plants were genotyped and in parallel evaluated for HIR. We corroborated earlier studies in that qhir1 has both a significantly positive effect on HIR but also a strong selective disadvantage, as indicated by significant segregation distortion. Altogether, we were able to narrow down the qhir1 locus to a 243 kb region flanked by markers X291 and X263.

Multispecies coexistence of trees in tropical forests: spatial signals of topographic niche differentiation increase with environmental heterogeneity

Neutral and niche theories give contrasting explanations for the maintenance of tropical tree species diversity. Both have some empirical support, but methods to disentangle their effects have not yet been developed. We applied a statistical measure of spatial structure to data from 14 large tropical forest plots to test a prediction of niche theory that is incompatible with neutral theory: that species in heterogeneous environments should separate out in space according to their niche preferences. We chose plots across a range of topographic heterogeneity, and tested whether pairwise spatial associations among species were more variable in more heterogeneous sites. We found strong support for this prediction, based on a strong positive relationship between variance in the spatial structure of species pairs and topographic heterogeneity across sites. We interpret this pattern as evidence of pervasive niche differentiation, which increases in importance with increasing environmental heterogeneity.

PI3K/Akt mediates expression of TNF-alpha mRNA and activation of NF-kappaB in calyculin A-treated primary osteoblasts

OBJECTIVE

The effect of calyculin A (CA), a serine/threonine protein phosphatase inhibitor, on tumor necrosis factor-alpha (TNF-alpha) in primary osteoblasts was investigated to determine whether protein phosphatases could affect primary osteoblasts and if so which signaling pathways would be involved.

MATERIALS AND METHODS

Primary osteoblasts were prepared from newborn rat calvaria. Cells were treated with 1 nM CA for different time periods. The expressions of TNF-alpha and GAPDH mRNA were determined by RT-PCR. Cell extracts were subjected to SDS-PAGE and the activation of Akt and NF-kappaB were analyzed by western blotting.

RESULTS

Calyculin A-treatment markedly increased the expression of TNF-alpha mRNA and enhanced the phosphorylation level of Akt (Ser473) in these cells. Pretreatment with the PI3K inhibitor LY294002 suppressed the increase in TNF-alpha mRNA expression and the phosphorylation of Akt in response to CA. Western blot analysis showed that CA stimulated the phosphorylation and nuclear translocation of NF-kappaB in primary osteoblasts, and these responses were blocked by pretreatment with LY294002.

CONCLUSION

Calyculin A elicits activation of PI3K/Akt pathway which leads to expression of TNF-alpha mRNA and activation of NF-kappaB. This NF-kappaB activation involves both phosphorylation and nuclear translocation of NF-kappaB.

Polymorphisms in IgG Fc receptor IIB regulatory regions associated with autoimmune susceptibility

Autoimmune diseases involve multiple genes. While functions of these genes are largely unknown, some may be related to an intrinsic hyperresponsiveness of B cells. B-cell responses are controlled by signaling thresholds through the B-cell antigen receptor (BCR) complex. The B1 isoform of type II IgG Fc receptors (FcgammaRIIB1) is exclusively expressed on B cells and serves as a negative regulator for inhibiting BCR-elicited activation. Thus, its allelic variants associated with functional deficits could be examined for possible associations with susceptibility to autoimmune diseases. We found that there are three types of polymorphisms in the reported FcgammaRIIB transcription regulatory regions in mouse strains. Compared to normal healthy mouse strains (group III), autoimmune disease-prone strains (group I) share three deletion sites: two in the promoter region and one in the third intron. Strains (group II) that per se are not autoimmune-prone, but have potentials to accelerate autoimmune diseases share two deletion sites in the third intron: one identical to that in group I and the other unique to group II. These polymorphisms correlated well with extents of down-regulation of FcgammaRIIB1 expression in germinal-center B cells upon stimulation with antigens and up-regulation of IgG antibody responses. Our data imply that these FcgammaRIIB polymorphisms are selected evolutionarily for natural defense against pathogens, and that such polymorphisms may, in turn, form the basis of one aspect of autoimmune susceptibility.

Genetically determined aberrant down-regulation of FcgammaRIIB1 in germinal center B cells associated with hyper-IgG and IgG autoantibodies in murine systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a multigenic disease associated with IgG hypergammaglobulinemia, IgG anti-nuclear antibodies and immune complex (IC)-type glomerulonephritis. In both human and murine SLE, one susceptibility allele has been mapped to the interval linked to the IgG Fc receptor II (FcgammaRII) gene on chromosome 1. In spontaneous SLE models of NZB and (NZB x NZW) F(1) mice, expression of FcgammaRIIB1, which acts as a negative regulator for B cells, was abnormally down-regulated in follicular germinal center B cells from aged mice, compared to findings in non-SLE NZW, while levels in non-germinal center B cells were practically identical. Such strain differences were also evident in young mice upon in vivo stimulation with foreign antigens. In the FcgammaRIIB promoter region, the NZB allele has two deletion sites, including transcription factor-binding sites. Analyses using (NZB x NZW) F(1) x NZW backcross mice showed that this NZB allele was significantly linked to hyper-IgG, irrespective of the MHC haplotype, while high levels of IgG antibodies specific for DNA were regulated by a combinatorial effect of the F(1)-unique MHC haplotype and the NZB FcgammaRIIB allele. Therefore, the FcgammaRIIB promoter polymorphism may possibly predispose to SLE through germinal center B cells abnormally down-regulating FcgammaRIIB1 expression upon autoantigen stimulations and thus escaping negative signals for IgG production.

Mutations in the ligand-binding domain of the kit receptor: an uncommon site in human piebaldism

Heterozygous mutations in the gene for the Kit transmembrane receptor have been identified recently in human piebaldism and mouse "dominant spotting." Interestingly, all of the 14 known missense mutations that cause depigmentation in these species map to the tyrosine kinase domain of the receptor, whereas none have involved the extracellular ligand-binding domain. In an attempt to detect these uncommon mutations, we screened the nine exons encoding the extracellular portion of Kit for single-strand conformation polymorphisms (SSCP) in eight piebald subjects previously reported to be negative for kinase mutations. Four of these eight kindreds proved to carry novel mutations. The first mutation, found in two apparently unrelated probands with mild piebaldism and English ancestry, substitutes an arginine for a highly conserved cysteine at codon 136. This substitution disrupts a putative disulfide bond required for formation of the second Ig-like (D2) loop of the Kit ligand-binding domain. The second mutation, detected in a piebald kindred characterized by unusually limited depigmentation, substitutes a threonine for an alanine at codon 178, a site just proximal to conserved cysteines at codons 183 and 186. The third mutation, occurring in a kindred with more extensive depigmentation, is a novel four-base insertion in exon 2 that results in a proximal frameshift and premature termination. The data strongly suggest that piebaldism can result from missense mutations in the Kit ligand-binding domain, although the resulting phenotype may be milder than that observed for null or kinase mutations. The apparent clustering of these uncommon mutations at or near the conserved cysteines for the D2 Ig-like loop further suggests a critical role for this region in Kit receptor function.

[Effects of injury to endothelial cells on the binding of t-PA to cultured human umbilical vein endothelial cells]

Tissue plasminogen activator (t-PA) plays an important role in fibrinolysis. When t-PA is bound to endothelial cells (EC), its catalytic efficiency is increased and is prevented from being inhibited by its inhibitor PAI. In this paper, diamine was used to cause injury to cultured human umbilical vein endothelial cells by lipoperoxidation, and selenium was used as an anti-oxidant. Radioassay and autoradiography were used to detect the effects of injury on the binding ability of t-PA to EC. The results showed that the binding ability of t-PA to EC was reduced significantly after injury to EC by lipid peroxidation. Selenium could inhibit this reduction to a certain extent. It suggests that the decrease of fibrinolysis was related with the decrease of the binding ability of t-PA to EC after EC was injured.

Ultrastructural observations on cercaria of Schistosoma japonicum

The present paper describes the ultrastructure of the surface topography, head organ, tegument, musculature, glandular system, primary alimentary tract and flame cells of the Chinese mainland strain of Schistosoma japonicum cercaria, as visualized with both scanning and transmission electron microscopes. The results not only illustrate the morphological features of the cercarial surface and its internal structure reflecting an adaptation to the aqueous habitat but also reveal the correlation between the morphological structure and physiological function.

Automatic extraction and registration of shock wave fronts from series interferograms of a flow field

Algorithms for extracting shock wave fronts from interferograms of a flow field and for registering time-series shock waves are proposed. Based on these, application software is developed on a PC-Vision 100 image-processing system. As application examples, interferograms of a primary high-explosive flow field and a real, solid rocket muzzle flow field are processed. The results indicate that the propagation velocity of the shock wave can be easily calculated with this method.

Decline in US stroke mortality in the era before antihypertensive therapy

BACKGROUND AND PURPOSE

This study was done to determine if reported declines in stroke mortality in the era before antihypertensive therapy are artifactual.

METHODS

This study involved analyses of national and state vital statistics data using adjusted and specific rates.

RESULTS

Adoption of the third revision of the International List of Causes of Death in 1921 produced an abrupt 6.6% decrease in stroke mortality rates, but otherwise, changes in disease classification systems had little effect on stroke mortality rates. Adoption of the second revision of the joint-cause manual produced a 9.2% drop in stroke death rates, but other revisions of the joint-cause selection rules had little effect. While rates for the expanding group of states in the death registration area progressively declined, rates for fixed component areas remained constant until around 1925 and then declined. Reselection of the underlying cause from aggregate multiple cause data for 1917, 1925, and 1940 using uniform selection rules confirmed a decline after 1925. Correlation analyses of rates of change for stroke and heart disease rates did not support a shift in diagnosis to explain the divergent trends.

CONCLUSIONS

The apparent decline in stroke mortality rates before 1925 is an artifact of changes in disease classification systems, joint-cause selection rules, and nonrandom incorporation of states with different mortality rates into the expanding registration area. The decline after 1925 could not be explained by changes in coding systems or joint-cause selection rules or by a shift in diagnosis from stroke to heart disease.

Observation of the beat between two independent light sources by a method of time-delayed laser-induced double gratings

A novel method of time-delayed laser-induced double gratings has been proposed to study the beat between two independent light sources. Our experimental results indicate that we can obtain good interference patterns even when the coherence time of the laser source is only a few picoseconds. This new technique can be used to measure the frequency difference between two laser fields.