Production study of Fr, Ra and Ac radioactive ion beams at ISOLDE, CERN

The presented paper discusses the production of radioactive ion beams of francium, radium, and actinium from thick uranium carbide (UCx ) targets at ISOLDE, CERN. This study focuses on the release curves and extractable yields of francium, radium and actinium isotopes. The ion source temperature was varied in order to study the relative contributions of surface and laser ionization to the production of the actinium ion beams. The experimental results are presented in the form of release parameters. Representative extractable yields per μ C are presented for222 - 231 Ac, several Ra and Fr isotopes in the mass ranges 214 ≤ A ≤ 233 and 205 ≤ A ≤ 231 respectively. The release efficiency for several isotopes of each of the studied elements was calculated by comparing their yields to the estimated in-target production rates modeled by CERN-FLUKA. The maximal extraction efficiency of actinium was calculated to be 2.1(6)% for a combination of surface ionization using a Ta ion source and resonant laser ionization using the two-step 438.58 nm, and 424.69 nm scheme.

Isomeric Excitation Energy for ^{99}In^{m} from Mass Spectrometry Reveals Constant Trend Next to Doubly Magic ^{100}Sn

The excitation energy of the 1/2^{-} isomer in ^{99}In at N=50 is measured to be 671(37) keV and the mass uncertainty of the 9/2^{+} ground state is significantly reduced using the ISOLTRAP mass spectrometer at ISOLDE/CERN. The measurements exploit a major improvement in the resolution of the multireflection time-of-flight mass spectrometer. The results reveal an intriguing constancy of the 1/2^{-} isomer excitation energies in neutron-deficient indium that persists down to the N=50 shell closure, even when all neutrons are removed from the valence shell. This trend is used to test large-scale shell model, ab initio, and density functional theory calculations. The models have difficulties describing both the isomer excitation energies and ground-state electromagnetic moments along the indium chain.

Serum interleukin-4 is elevated in clinical drug-induced liver injury

BACKGROUND

Drug-induced liver injury (DILI) remains a challenging diagnosis due to an absence of specific biomarkers. DILI due to volatile anaesthetics (VA-DILI) is characterised by trifluoroacetyl and CYP2E1 antibodies, but may not be seen for weeks after injury. Interleukin-4 (IL-4) may be involved in the production of these antibodies and may serve as a clinically useful early biomarker of VA-DILI.

AIM

To prospectively compare serum IL-4 levels between patients who develop VA-DILI and controls following exposure to the volatile anaesthetic.

METHODS

A nested case-control study of patients exposed to VA during surgery was conducted. Thirteen DILI cases were identified from the original cohort, and 26 controls were matched according to age, sex and VA agent. Serum samples were collected before and 48-96 h after VA exposure, and analysed for IL-4 using quantitative enzyme-linked immunosorbent assay techniques.

RESULTS

There was a statistically significant difference in serum IL-4 in post-VA samples between DILI cases and controls (control: 0.030 pg/mL, IQR: 0.030 - 0.030 pg/mL vs DILI: 0.044 pg/mL, IQR: 0.030 - 0.061 pg/mL; p = 0.039). A greater proportion of DILI cases had post-VA IL-4 levels above the assay lower limit of detection compared to controls (control: 23% vs DILI: 69%; p = 0.013).

CONCLUSION

IL-4 is a potential biomarker of DILI. Clinical diagnosis and understanding of DILI disease mechanisms may be improved by further investigation of novel biomarkers, and this IL-4 signal in serum is important as proof of concept for prospective study designs.

Endothelin-1 induces chondrocyte senescence and cartilage damage via endothelin receptor type B in a post-traumatic osteoarthritis mouse model

OBJECTIVES

This study aimed to investigate the role of endothelin-1 (ET-1), originally known as the potent vasoconstrictor, and its receptors in chondrocyte senescence and osteoarthritis (OA) development.

METHOD

Temporal changes of ET-1 and its receptors with OA development were characterized in a posttraumatic OA (PTOA) mouse model at time zero, 1-month and 4-month after surgical induction via destabilization of medial meniscus (DMM). A transgenic ET-1 overexpression (TET-1) mouse model was deployed to assess the impact of upregulated ET-1 on chondrocyte senescence and cartilage degradation. Effects of endothelin receptor blockade on chondrocyte senescence and OA development were further examined both in vitro and in vivo.

RESULTS

Local expression of ET-1 in subchondral bone and synovium upregulated after DMM with an increase of plasma ET-1 level from 3.18 ± 0.21 pg/ml at time zero to 6.47 ± 0.34 pg/ml at 4-month post-surgery. Meanwhile, endothelin type B receptor (ET_BR) (53.31 ± 2.42% to 83.8 ± 2.65%) and p16^INK4a (10.91 ± 1.07% to 28.2 ± 1.0%) positve chondrocytes accumulated in articular cartilage since 1-month prior to cartilage loss at 4-month post-surgery. Overexpressed ET-1 promoted p16^INK4a-positive senescent chondrocytes accumulation and cartilage degradation in TET-1 mice. Selective blockade of ET_BR, but not ET_AR, lowered the expression of p16^INK4a in ET-1 or H₂O₂-induced chondrocyte senescence model, and mitigated the severity of murine PTOA. Intriguingly, reactive oxygen species (ROS) scavenger, Vitamin C, could rescue ET-1-induced chondrocyte senescence in vitro associated with restoration of mitochondrial dynamics.

CONCLUSION

ET-1 could induce chondrocytes senescence and cartilage damages via ET_BR in PTOA.

Identification of key residues involved in adrenomedullin binding to the AM1 receptor

BACKGROUND AND PURPOSE

Adrenomedullin (AM) is a peptide hormone whose receptors are members of the class B GPCR family. They comprise a heteromer between the GPCR, the calcitonin receptor-like receptor and one of the receptor activity-modifying proteins 1-3. AM plays a significant role in angiogenesis and its antagonist fragment AM22-52 can inhibit blood vessel and tumour growth. The mechanism by which AM interacts with its receptors is unknown.

EXPERIMENTAL APPROACH

We determined the AM22-52 binding epitope for the AM1 receptor extracellular domain using biophysical techniques, heteronuclear magnetic resonance spectroscopy and alanine scanning.

KEY RESULTS

Chemical shift perturbation experiments located the main binding epitope for AM22-52 at the AM1 receptor to the C-terminal 8 amino acids. Isothermal titration calorimetry of AM22-52 alanine-substituted peptides indicated that Y52, G51 and I47 are essential for AM1 receptor binding and that K46 and P49 and R44 have a smaller role to play. Characterization of these peptides at the full-length AM receptors was assessed in Cos7 cells by cAMP assay. This confirmed the essential role of Y52, G51 and I47 in binding to the AM1 receptor, with their substitution resulting in ≥100-fold reduction in antagonist potency compared with AM22-52 . R44A, K46A, S48A and P49A AM22-52 decreased antagonist potency by approximately 10-fold.

CONCLUSIONS AND IMPLICATIONS

This study localizes the main binding epitope of AM22-52 to its C-terminal amino acids and distinguishes essential residues involved in this binding. This will inform the development of improved AM receptor antagonists.

In vivo characterization of transplanted human embryonic stem cell-derived pancreatic endocrine islet cells

OBJECTIVES

Islet-like clusters (ILCs), differentiated from human embryonic stem cells (hESCs), were characterized both before and after transplantation under the kidney capsule of streptozotocin-induced diabetic immuno-incompetent mice.

MATERIALS AND METHODS

Multiple independent ILC preparations (n = 8) were characterized by immunohistochemistry, flow cytometry and cell insulin content, with six preparations transplanted into diabetic mice (n = 42), compared to controls, which were transplanted with either a human fibroblast cell line or undifferentiated hESCs (n = 28).

RESULTS

Prior to transplantation, ILCs were immunoreactive for the islet hormones insulin, C-peptide and glucagon, and for the ductal epithelial marker cytokeratin-19. ILCs also had cellular insulin contents similar to or higher than human foetal islets. Expression of islet and pancreas-specific cell markers was maintained for 70 days post-transplantation. The mean survival of recipients was increased by transplanted ILCs as compared to transplanted human fibroblast cells (P < 0.0001), or undifferentiated hESCs (P < 0.042). Graft function was confirmed by secretion of human C-peptide in response to an oral bolus of glucose.

CONCLUSIONS

hESC-derived ILC grafts continued to contain cells that were positive for islet endocrine hormones and were shown to be functional by their ability to secrete human C-peptide. Further enrichment and maturation of ILCs could lead to generation of a sufficient source of insulin-producing cells for transplantation into patients with type 1 diabetes.

Decoupling of normal CD40/interleukin-4 immunoglobulin heavy chain switch signal leads to genomic instability in SGH-MM5 and RPMI 8226 multiple myeloma cell lines

The processes mediating genomic instability and clonal evolution are obscure in multiple myeloma (MM). Acquisition of new chromosomal translocations into the switch region of the immunoglobulin heavy chain (IgH) gene (chromosome 14q32) in MM, often heralds transformation to more aggressive disease. Since the combined effects of CD40 plus interleukin-4 (IL-4) mediate IgH isotype class switch recombination (CSR), and this process involves DNA double strand break repair (DSBR), we hypothesized that CD40 and/or IL-4 activation of MM cells could induce abnormal DNA DSBR and lead to genomic instability and clonal evolution. In this study, we show that MM cell lines that are optimally triggered via CD40 and/or IL-4 demonstrate abnormal decoupling of IL-4 signal transduction from CD40. Specifically, CD40 alone was sufficient to trigger maximal growth of tumor cells. We further demonstrate that CD40 triggering induced both DNA DSBs as well as newly acquired karyotypic abnormalities in MM cell lines. Importantly, these observations were accompanied by induction of activation induced cytidine deaminase expression, but not gross apoptosis. These data support the role of abnormal CD40 signal transduction in mediating genomic instability, suggesting a role for the CD40 pathway and intermediates in myelomagenesis and clonal evolution in vivo.

Genome-wide mapping with biallelic markers in Arabidopsis thaliana

Single-nucleotide polymorphisms, as well as small insertions and deletions (here referred to collectively as simple nucleotide polymorphisms, or SNPs), comprise the largest set of sequence variants in most organisms. Positional cloning based on SNPs may accelerate the identification of human disease traits and a range of biologically informative mutations. The recent application of high-density oligonucleotide arrays to allele identification has made it feasible to genotype thousands of biallelic SNPs in a single experiment. It has yet to be established, however, whether SNP detection using oligonucleotide arrays can be used to accelerate the mapping of traits in diploid genomes. The cruciferous weed Arabidopsis thaliana is an attractive model system for the construction and use of biallelic SNP maps. Although important biological processes ranging from fertilization and cell fate determination to disease resistance have been modelled in A. thaliana, identifying mutations in this organism has been impeded by the lack of a high-density genetic map consisting of easily genotyped DNA markers. We report here the construction of a biallelic genetic map in A. thaliana with a resolution of 3.5 cM and its use in mapping Eds16, a gene involved in the defence response to the fungal pathogen Erysiphe orontii. Mapping of this trait involved the high-throughput generation of meiotic maps of F2 individuals using high-density oligonucleotide probe array-based genotyping. We developed a software package called InterMap and used it to automatically delimit Eds16 to a 7-cM interval on chromosome 1. These results are the first demonstration of biallelic mapping in diploid genomes and establish means for generalizing SNP-based maps to virtually any genetic organism.

Chinese migrants' mental health and adjustment to life in New Zealand

OBJECTIVE

The purpose of this study was to identify and assess the relative importance of predictors of the self-rated adjustment and psychiatric morbidity of recent Chinese migrants.

METHOD

Chinese migrants (n = 271) living in Auckland and aged 15 years or older completed a postal questionnaire that included the Chinese Health Questionnaire (CHQ). The majority of respondents came from Hong Kong and Taiwan.

RESULTS

Most respondents did not report major adjustment problems. The psychiatric morbidity rate was 19%. Major predictors of experiencing problems included rejection by locals, being aged 26-35 years or over 45 years and low English proficiency. Major predictors of poor adjustment included unemployment, low English proficiency, lack of university education, younger age, shorter residency, expectations not met and regrets about coming to New Zealand. Predictors of minor mental disorder included regretting coming, female gender and younger age. For migrants resident 2 years or less, unemployment and underemployment were additional risk factors. Mothers with absent husbands and young people with absent parents also had elevated rates of mental disorder.

CONCLUSIONS

Although the overall prevalence of mental disorder for this sample of recent migrants appears to be similar to that of the general population, significant risk factors were identified. The findings extend knowledge of the adjustment and the mental health of migrants and provide potential focal points for primary and secondary prevention interventions.

A domain containing leucine-zipper-like motifs mediate novel in vivo interactions between the thyroid hormone and retinoic acid receptors

The thyroid hormones and retinoic acid are potent modulators of differentiation, development, and gene expression. The transcriptional activities of these ligands are mediated by closely related nuclear receptors which bind and activate identical hormone responsive DNA elements. We noticed that a region within the ligand binding or E domain is well conserved between receptors for these hormones. This region contains hydrophobic heptad repeats that are structurally similar to the leucine-zipper dimerization domain. To study the function of this conserved domain, we examined the transcriptional responses of thyroid hormone receptor/c-erbA deletion mutants which lacked the heptad repeats. We previously reported that the chick c-erbA-alpha possesses hormone-independent (constitutive) activity in cells which express endogenous rat thyroid hormone receptor. We now demonstrate that this activity is abolished upon deletion of the conserved heptad repeats. This suggests that the heptad repeats mediate in vivo interactions between chick c-erbA and rat thyroid hormone receptors. To further test this hypothesis deletion mutants of chick c-erbA were constructed which contained all eight heptad repeats but which lacked the zinc-finger DNA binding domain. Although these mutants are transcriptionally inactive, they act in a dominant-negative fashion to block trans-activation by both the chick c-erbA-alpha and the endogenous thyroid hormone and retinoic acid receptors. We suggest that the heptad repeats mediate the formation of inactive mutant/wild-type hetero-dimers. Dimer formation suggests a mechanism to account for the dominant-negative phenotypes displayed by nonhormone binding variants of c-erbA, the proto-oncoprotein v-erbA and patients with the generalized thyroid hormone resistance syndrome.

Genetic control of differentiation of the Caenorhabditis elegans touch receptor neurons

The genetic control of neuronal differentiation has been studied by examining mutations that affect the development and function of the six touch receptor neurons of the nematode Caenorhabditis elegans. By screening for touch-insensitive mutants, it has been possible to identify 18 genes (represented by 417 mutations) that are required at various stages in the developmental program for touch cell differentiation. Two of the genes are needed for the generation of precursors in the touch cell lineages; without the precursors, touch cells are not made. A third gene, mec-3, specifies the differentiation of the touch cells, probably by acting as a transcription factor. The remaining 15 genes are likely targets of mec-3 action; mutants defective in these genes have nonfunctioning, yet differentiated, touch cells. Some of these latter genes are needed for the formation of cell-specific components of the touch cells, such as a set of microtubules that are only found in these cells. The study of the touch genes should help us understand how touch cell fate is determined, how microtubule form is specified, and, perhaps, how mechanical stimuli are transduced.

Models of molecular evolution. 2. Stereospecificity of dipeptide syntheses by means of cyanamides and carbodiimides

Acetyl, benzyloxycarbonyl and tosyl protected DL-alanine, DL-leucine, DL-methionine, DL-phenylalanine, and DL-valine were condensed with DL-amino acid methyl esters. Cyanamide, diethylcyanamide, diisopropyl carbodiimide, dicyclohexyl carbodiimide, and N-cyclohexyl-N'-(2-morpholino ethyl) carbodiimide-N''-methotosylate served as condensing reagents. Water, methanol, and dimethylformamide were used as reaction media. The stereochemical course of these dipeptide syntheses was elucidated by means of 13C-n.m.r. spectroscopy. The formation of L-L and D-D bonds (isotactic sequences) was favoured in ca. 80% of all condensations. L-L/L-D (D-D/D-L) ratios of up to 6:1 were found.