In vitro analysis of allogeneic lymphocyte interaction. I. Characterization and cellular origin of an Ia-positive helper factor- allogeneic effect factor

A soluble allogeneic effect factor (AEF) was produced by using H-2 congenic mouse strains and a serum.free cell culture medium. An AEF derived from untreated activated responder cells and irradiated stimulator cells provided helper cell function in a primary and secondary antibody response for both T-cell-depleted responder B cells and stimulator B cells. This interaction may be determined by genes situated in the I-A and I-B regions: additional K-region control was not excluded. Ia antigens, but neither H-2 nor Ig determinants are molecular constituents of AEF. The active components of this AEF consist, in part, of Ia antigens derived from both the activated responder cell population and irradiated stimulator cell population. An AEF derived from Ia negative responder cells and irradiated T-cell- depleted stimulator cells helps a secondary antibody response of T-cell- depleted stimulator B cells but not responder B cells. This genetically restricted AEF contains Ia antigens determined by the stimulator haplotype but not the responder haplotype. The priming antigen, DNP- keyhole limpet hemocyanin, is not a component of restricted AEF. The data suggest that restricted AEF may be a product of a stimulator B cell and/or macrophage. They support the hypothesis that the recognition by allogeneic T cells of Ia antigens on B cells activates the B cell to IgG antibody production

Primary immunodeficiency in Hong Kong and the use of genetic analysis for diagnosis

Objectives. To review the management of primary immunodeficiency and discuss recent advances in genetic analysis. Design. Retrospective study. Setting. University teaching hospital, Hong Kong. Patients. Children diagnosed with primary immunodeficiency and followed up in the immunology clinic during the period 1988 to 2003. Main outcome measures. Demographic data, co-morbidities and treatment of patients, outcome and complications; identification of disease by genetic mutations. Results. Medical records of a total of 117 patients (72 male, 45 female) diagnosed with primary immunodeficiency in the Department of Paediatrics and Adolescent Medicine, Queen Mary Hospital, Hong Kong during the past 15 years (1988-2003) were reviewed. All patients were followed up in the immunology clinic. Some patients had been referred from the private sector or other hospitals for immunological workup. Six categories of primary immunodeficiency were identified: predominantly humoral defect (n=50), predominantly cellular defect (n=22), combined humoral and cellular defect (n=5), phagocytic defect (n=18), complement disorders (n=4), and others (n=18). Although infection was the underlying cause of most co-morbidities and mortality, autoimmune (n=7) and allergic (n=23) manifestations were common. In addition, three patients developed lymphoma. Recent advances in the genetic diagnosis of several types of primary immunodeficiency were also reviewed: X-linked Wiskott-Aldrich syndrome, X-linked chronic granulomatous disease, X-linked agammaglobulinaemia, X-linked lymphoproliferative syndrome, leukocyte adhesion disease type I, and X-linked hyperimmunoglobulin M syndrome. This provides an invaluable means of understanding the molecular basis of primary immunodeficiency and has important clinical applications. Conclusions. Co-morbidities like autoimmune disease and allergic disease are common in patients with primary immunodeficiency and should be carefully evaluated. Likewise, a diagnosis of primary immunodeficiency should be considered when evaluating patients with these conditions. Rapid progress in the field of molecular genetics will enable definite and early diagnosis, and more importantly, potential curative therapy to be administered.published_or_final_versio

Molecular Diagnosis for Paediatric Genetic Disorders Using Whole Exome Sequencing of the Next Generation Sequencing Technology

Oral PresentationMolecular diagnosis for paediatric genetic diseases is important for targeted or tailored treatment, more informative genetic counselling and guiding the families for prenatal or pre-implantation diagnosis. Traditionally, linkage analysis using large multiplex families or multiple families with the same molecular cause is essential and the process could take years before a diagnosis can be reached. Candidate gene screening is usually the only method available for clinical laboratories for genetic diseases in Hong Kong. Next generation sequencing technology has virtually revolutionised the way genetic studies are conducted and provides opportunities for molecular diagnosis for genetic disorders that were never available before. With the possibility of sequencing the whole genome or almost all the coding exons of the genome, the method does not require the availability of large, multiple affected families and prior knowledge of candidate causal genes. It can be applied to a single patient or, as a usual practice, whole genome or whole exome sequencing for the patient plus parents. For whole exome sequencing (WES), it usually produces up to 100 million short sequencing reads of usually 100bp long. These short reads were firstly compared with sequences of a reference human genome and mapped to genomic regions from which they were generated. Each position (base pair) of a coding exon is usually covered with dozens to hundreds of sequencing reads. Analysing the sequences of these reads allows for identification of mutations that are different from the reference sequences. For WES for a single individual, up to 100,000 variants can be identified, with some of which are common variants in a population and some of which rare or private. The population frequencies of these variants are looked up in public databases such as those from the 1000 Genome Project or ESP6500, a project that sequenced 6500 individuals in the US. An internal database is also established with WES data from 200 samples from the local population. For rare, severe genetic disorders that are likely to be caused by mutations from a single gene, we can safely rule out the common (>1% in a population) variants and only focus on the rare or private variants. The nature of the mutations, such as with or without amino acid changes, changes in the open reading frame of the protein, the nature of the amino acid changes (similarity of the amino acid changed to), the conservation of this amino acid in different species, and the function of the gene in relationship to the disease phenotype, are considered to help pinpoint the causal mutations. We will present examples on using WES for molecular diagnosis for paediatric genetic disorders in our Department. These include detection of de novo mutations (mutations that are not detected in parents), somatic mutations and compound heterozygous mutations, and mutations missed by traditional laboratory testing, which demonstrated the power of this new technology in providing accurate molecular diagnosis.published_or_final_versio

Human oropharynx as natural reservoir of Streptobacillus hongkongensis

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High prevalence of Escherichia coli sequence type 131 among antimicrobial-resistant E. coli isolates from geriatric patients

Previous work on the subclones within Escherichia coli ST131 predominantly involved isolates from Western countries. This study assessed the prevalence and antimicrobial resistance attributed to this clonal group. A total of 340 consecutive, non-duplicated urinary E. coli isolates originating from four clinical laboratories in Hong Kong in 2013 were tested. ST131 prevalence among the total isolates was 18.5 % (63/340) and was higher among inpatient isolates (23.0 %) than outpatient isolates (11.8 %, P<0.001), and higher among isolates from patients aged ≥65 years than from patients aged 18–50 years and 51–64 years (25.4 vs 3.4 and 4.0 %, respectively, P<0.001). Of the 63 ST131 isolates, 43 (68.3 %) isolates belonged to the H30 subclone, whereas the remaining isolates belonged to H41 (n = 17), H54 (n = 2) and H22 (n = 1). All H30 isolates were ciprofloxacin-resistant, of which 18.6 % (8/43) belonged to the H30-Rx subclone. Twenty-six (41.3 %) ST131 isolates were ESBL-producers, of which 19 had bla CTX-M-14 (12 non-H30-Rx, two H30-Rx and five H41), six had bla CTX-M-15 (five non-H30-Rx and one H30-Rx) and one was bla CTX-M-negative (H30). In conclusion, ST131 accounts for a large share of the antimicrobial-resistant E. coli isolates from geriatric patients. Unlike previous reports, ESBL-producing ST131 strains mainly belonged to non-H30-Rx rather than the H30-Rx subclone, with bla CTX-M-14 as the dominant enzyme type.postprin

A comparison of prognostic significance of strong ion gap (SIG) with other acid-base markers in the critically ill: a cohort study

BACKGROUND: This cohort study compared the prognostic significance of strong ion gap (SIG) with other acid-base markers in the critically ill. METHODS: The relationships between SIG, lactate, anion gap (AG), anion gap albumin-corrected (AG-corrected), base excess or strong ion difference-effective (SIDe), all obtained within the first hour of intensive care unit (ICU) admission, and the hospital mortality of 6878 patients were analysed. The prognostic significance of each acid-base marker, both alone and in combination with the Admission Mortality Prediction Model (MPM0 III) predicted mortality, were assessed by the area under the receiver operating characteristic curve (AUROC). RESULTS: Of the 6878 patients included in the study, 924 patients (13.4 %) died after ICU admission. Except for plasma chloride concentrations, all acid-base markers were significantly different between the survivors and non-survivors. SIG (with lactate: AUROC 0.631, confidence interval [CI] 0.611-0.652; without lactate: AUROC 0.521, 95 % CI 0.500-0.542) only had a modest ability to predict hospital mortality, and this was no better than using lactate concentration alone (AUROC 0.701, 95 % 0.682-0.721). Adding AG-corrected or SIG to a combination of lactate and MPM0 III predicted risks also did not substantially improve the latter's ability to differentiate between survivors and non-survivors. Arterial lactate concentrations explained about 11 % of the variability in the observed mortality, and it was more important than SIG (0.6 %) and SIDe (0.9 %) in predicting hospital mortality after adjusting for MPM0 III predicted risks. Lactate remained as the strongest predictor for mortality in a sensitivity multivariate analysis, allowing for non-linearity of all acid-base markers. CONCLUSIONS: The prognostic significance of SIG was modest and inferior to arterial lactate concentration for the critically ill. Lactate concentration should always be considered regardless whether physiological, base excess or physical-chemical approach is used to interpret acid-base disturbances in critically ill patients

Coherent multi-flavour spin dynamics in a fermionic quantum gas

Microscopic spin interaction processes are fundamental for global static and dynamical magnetic properties of many-body systems. Quantum gases as pure and well isolated systems offer intriguing possibilities to study basic magnetic processes including non-equilibrium dynamics. Here, we report on the realization of a well-controlled fermionic spinor gas in an optical lattice with tunable effective spin ranging from 1/2 to 9/2. We observe long-lived intrinsic spin oscillations and investigate the transition from two-body to many-body dynamics. The latter results in a spin-interaction driven melting of a band insulator. Via an external magnetic field we control the system's dimensionality and tune the spin oscillations in and out of resonance. Our results open new routes to study quantum magnetism of fermionic particles beyond conventional spin 1/2 systems.Comment: 9 pages, 5 figure

Targeting quiescent leukemic stem cells using second generation autophagy inhibitors

In chronic myeloid leukemia (CML), tyrosine kinase inhibitor (TKI) treatment induces autophagy that promotes survival and TKI-resistance in leukemic stem cells (LSCs). In clinical studies hydroxychloroquine (HCQ), the only clinically approved autophagy inhibitor, does not consistently inhibit autophagy in cancer patients, so more potent autophagy inhibitors are needed. We generated a murine model of CML in which autophagic flux can be measured in bone marrow-located LSCs. In parallel, we use cell division tracing, phenotyping of primary CML cells, and a robust xenotransplantation model of human CML, to investigate the effect of Lys05, a highly potent lysosomotropic agent, and PIK-III, a selective inhibitor of VPS34, on the survival and function of LSCs. We demonstrate that long-term haematopoietic stem cells (LT-HSCs: Lin−Sca-1+c-kit+CD48−CD150+) isolated from leukemic mice have higher basal autophagy levels compared with non-leukemic LT-HSCs and more mature leukemic cells. Additionally, we present that while HCQ is ineffective, Lys05-mediated autophagy inhibition reduces LSCs quiescence and drives myeloid cell expansion. Furthermore, Lys05 and PIK-III reduced the number of primary CML LSCs and target xenografted LSCs when used in combination with TKI treatment, providing a strong rationale for clinical use of second generation autophagy inhibitors as a novel treatment for CML patients with LSC persistence