Publications by authors named "Kwok W"

The charge and spin of the electrons in solids have been extensively exploited in electronic devices and in the development of spintronics. Another attribute of electrons-their orbital nature-is attracting growing interest for understanding exotic phenomena and in creating the next-generation of quantum devices such as orbital qubits. Here, we report on orbital-flop induced magnetoresistance anisotropy in CeSb.

View Article and Find Full Text PDF

Given the immense antigenic load present in the microbiome, we hypothesized that microbiota mimotopes can be a persistent trigger in human autoimmunity via cross-reactivity. Using antiphospholipid syndrome (APS) as a model, we demonstrate cross-reactivity between non-orthologous mimotopes expressed by a common human gut commensal, Roseburia intestinalis (R. int), and T and B cell autoepitopes in the APS autoantigen β-glycoprotein I (βGPI).

View Article and Find Full Text PDF

The development of peptide-MHC class II multimers has provided a novel approach in studying antigen-specific CD4 T-cells and extended the knowledge of these T cells in various disease settings, including infectious diseases, autoimmune diseases, cancer, and allergies. This chapter discusses the various applications of the peptide-MHC class II multimer technologies, specifically their uses in the evaluation of antigen-specific CD4 T-cells ex vivo, and their uses in epitope identification.

View Article and Find Full Text PDF

Next-generation targeted sequencing of HLA-DRB1 and HLA-DRB3, -DRB4, and -DRB5 (abbreviated as DRB345) provides high resolution of functional variant positions to investigate their associations with type 1 diabetes risk and with autoantibodies against insulin (IAA), GAD65 (GADA), IA-2 (IA-2A), and ZnT8 (ZnT8A). To overcome exceptional DR sequence complexity as a result of high polymorphisms and extended linkage disequilibrium among the DR loci, we applied a novel recursive organizer (ROR) to discover disease-associated amino acid residues. ROR distills disease-associated DR sequences and identifies 11 residues of DRB1, sequences of which retain all significant associations observed by DR genes.

View Article and Find Full Text PDF

A cyclen backbone was utilized to study the effect of backbone rigidity on Eu(iii) luminescence sensitization using a 1,2-HOPO derivative and 2-thenoyltrifluoroacetonate (TTA) as chromophores. The restriction of molecular movement of brought about by the increased rigidity provided a tightly packed coordination environment for the octadentate Eu(iii) center which resulted in the highest overall quantum yield (30.2%) and sensitization efficiency (64.

View Article and Find Full Text PDF

With the discovery of charge-density waves (CDWs) in most members of the cuprate high-temperature superconductors, the interplay between superconductivity and CDWs has become a key point in the debate on the origin of high-temperature superconductivity. Some experiments in cuprates point toward a CDW state competing with superconductivity, but others raise the possibility of a CDW-superconductivity intertwined order or more elusive pair-density waves (PDWs). Here, we have used proton irradiation to induce disorder in crystals of [Formula: see text] and observed a striking 50% increase of [Formula: see text], accompanied by a suppression of the CDWs.

View Article and Find Full Text PDF

Background: Allergen immunotherapy using synthetic peptide T-cell epitopes (Cat-PAD) from the major cat allergen Fel d 1 has been shown, in allergen exposure studies, to significantly reduce symptoms of allergic rhinoconjunctivitis in cat-allergic subjects. However, the immunological mechanisms underlying clinical benefit remain only partially understood. Since previous studies of whole allergen immunotherapy demonstrated a reduction in the frequency of allergen-specific (MHC II tetramer ) CD4 T cells expressing the chemokine receptor CRTh2, we assessed the impact of Cat-PAD on the frequency and functional phenotype of Fel d 1-specific CD4 T cells.

View Article and Find Full Text PDF

We report the two-dimensional (2D) natural heterostructure [PbSbS][Au Te] ( x = 0.52-0.36) which shows anomalous, transverse nonsaturating negative magnetoresistance (MR).

View Article and Find Full Text PDF

The ability of type II superconductors to carry large amounts of current at high magnetic fields is a key requirement for future design innovations in high-field magnets for accelerators and compact fusion reactors, and largely depends on the vortex pinning landscape comprised of material defects. The complex interaction of vortices with defects that can be grown chemically, e.g.

View Article and Find Full Text PDF

In type 1 diabetes (T1D), proinsulin is a major autoantigen and the insulin B:9-23 peptide contains epitopes for CD4 T cells in both mice and humans. This peptide requires carboxyl-terminal mutations for uniform binding in the proper position within the mouse IA or human DQ8 major histocompatibility complex (MHC) class II (MHCII) peptide grooves and for strong CD4 T cell stimulation. Here, we present crystal structures showing how these mutations control CD4 T cell receptor (TCR) binding to these MHCII-peptide complexes.

View Article and Find Full Text PDF

We have reported that the major histocompatibility molecule HLA-DQ2 (DQA1*05:01/DQB1*02:01) (DQ2) is relatively resistant to HLA-DM (DM), a peptide exchange catalyst for MHC class II. In this study, we analyzed the role of DQ2/DM interaction in the generation of DQ2-restricted gliadin epitopes, relevant to celiac disease, or DQ2-restricted viral epitopes, relevant to host defense. We used paired human APC, differing in DM expression (DM versus DM) or differing by expression of wild-type DQ2, versus a DM-susceptible, DQ2 point mutant DQ2α+53G.

View Article and Find Full Text PDF

Mitochondrial (m) Ca influx is largely dependent on membrane potential (ΔΨ), whereas mCa efflux occurs primarily via Ca ion exchangers. We probed the kinetics of Ca/H exchange (CHE) in guinea pig cardiac muscle mitochondria. We tested if net mCa flux is altered during a matrix inward H leak that is dependent on matrix H pumping by ATP hydrolysis at complex V (FF-ATPase).

View Article and Find Full Text PDF

A new class of sky-blue-emitting arylgold(iii) complexes containing tridentate bis-cyclometalating ligands derived from 2,6-diphenylpyridine (C^N^C) has been successfully designed and synthesized. By systematically varying the electron-withdrawing groups from cyano, fluoro, and trifluoromethyl to trifluoromethoxy groups on the phenyl ring of the tridentate C^N^C ligands, the emission maxima of these complexes have been significantly blue-shifted from 492 nm to 466 nm in dichloromethane solution. In addition, the higher excited state distortion with respect to the ground state associated with the multiple fluoro substitutions at the tridentate ligand has been successfully reduced by the employment of trifluoromethyl and trifluoromethoxy groups, as revealed by the Huang-Rhys factor.

View Article and Find Full Text PDF

A adenosine receptor (AAR) agonists are effective at limiting injury caused by ischemia/reperfusion injury of the heart in experimental animal models. However, understanding of their mechanism of action, which is likely multifactorial, remains incomplete. In prior studies, it has been demonstrated that AAR-mediated ischemic protection is blocked by glibenclamide and is absent in Kir6.

View Article and Find Full Text PDF

Background And Objective: Bronchiolitis obliterans syndrome (BOS) after haematopoietic stem cell transplantation (HSCT) presents with lung function decline. The pattern of lung function decline after BOS diagnosis could impact prognostication of BOS as a complication after HSCT. The aim of this study was to assess the impact of lung function decline on overall survival (OS) in BOS subjects.

View Article and Find Full Text PDF

Negative longitudinal magnetoresistances (NLMRs) have been recently observed in a variety of topological materials and often considered to be associated with Weyl fermions that have a defined chirality. Here we report NLMRs in non-Weyl GaAs quantum wells. In the absence of a magnetic field the quantum wells show a transition from semiconducting-like to metallic behaviour with decreasing temperature.

View Article and Find Full Text PDF

Infection and vaccination can lead to activation of autoreactive T cells, including the activation of cross-reactive T cells. However, detecting these cross-reactive T cells and identifying the non-self and self-antigen epitopes is difficult. The current study demonstrates the utility of a novel approach that effectively accomplishes both.

View Article and Find Full Text PDF

The new compound NaCuSe forms by the reaction of CuO and Cu in a molten sodium polyselenide flux, with the existence of CuO being unexpectedly critical to its synthesis. It adopts a layered hexagonal structure (space group P6/ mmc with cell parameters a = 3.9931(6) Å and c = 25.

View Article and Find Full Text PDF

Background: Allergen-specific immunotherapy (AIT) is the only available treatment for allergic diseases that can induce specific immune tolerance to allergens. The key mechanisms involved in this process include changes in allergen-specific regulatory T (Treg) cells.

Methods: We studied 25 allergic rhinitis patients undergoing subcutaneous house dust mite-specific immunotherapy.

View Article and Find Full Text PDF

DRB4*01:01 (DRB4) is a secondary HLA-DR product that is part of the high-risk DR4/DQ8 haplotype that is associated with type 1 diabetes (T1D). DRB4 shares considerable homology with HLA-DR4 alleles that predispose to autoimmunity, including DRB1*04:01 and DRB1*04:04. However, the DRB4 protein sequence includes distinct residues that would be expected to alter the characteristics of its binding pockets.

View Article and Find Full Text PDF

CD4+ T cell responses are thought to play a role in type 1 diabetes (T1D). However, detection and characterization of T cells that respond to beta cell epitopes in subjects with T1D has been limited by technical obstacles, including the inherently low frequencies in peripheral blood and variable responsiveness of individual subjects to single epitopes. We implemented a multicolor staining approach that allows direct ex vivo characterization of multiple CD4+ T cell specificities in a single sample.

View Article and Find Full Text PDF

Correction for 'Unsupervised capture and profiling of rare immune cells using multi-directional magnetic ratcheting' by Coleman Murray et al., Lab Chip, 2018, 18, 2396-2409.

View Article and Find Full Text PDF

Objectives: The aim of this study was to evaluate a feline coronavirus (FCoV) reverse transcriptase quantitative PCR (RT-qPCR) on fine-needle aspirates (FNAs) from mesenteric lymph nodes (MLNs) collected in sterile saline for the purpose of diagnosing non-effusive feline infectious peritonitis (FIP) in cats.

Methods: First, the ability of the assay to detect viral RNA in MLN FNA preparations compared with MLN biopsy preparations was assessed in matched samples from eight cats. Second, a panel of MLN FNA samples was collected from a series of cats representing non-effusive FIP cases (n = 20), FCoV-seropositive individuals (n = 8) and FCoV-seronegative individuals (n = 18).

View Article and Find Full Text PDF