bluuebunny/crossref_metadata_2025 huggingface dataset:
COUP-TFs regulate eye development by controlling factors essential for optic vesicle morphogenesis
Authors: Tang Ke , Xie Xin , Park Joo-In , Jamrich Milan , Tsai Sophia , Tsai Ming-Jer
Published: February 2010

Transcriptional networks, which are initiated by secreted proteins, cooperate with each other to orchestrate eye development. The establishment of dorsal/ventral polarity, especially dorsal specification in the optic vesicle, is poorly understood at a molecular and cellular level. Here, we show that COUP-TFI (Nr2f1) and COUP-TFII (Nr2f2) are highly expressed in the progenitor cells in the developing murine eye. Phenotype analysis of COUP-TFI and COUP-TFII single-gene conditional knockout mouse models suggests that COUP-TFs compensate for each other to maintain morphogenesis of the eye. However, in eye-specific COUP-TFI/TFII double-knockout mice, progenitor cells at the dorso-distal optic vesicle fail to differentiate appropriately, causing the retinal pigmented epithelium cells to adopt a neural retina fate and abnormal differentiation of the dorsal optic stalk; the development of proximo-ventral identities, neural retina and ventral optic stalk is also compromised. These cellular defects in turn lead to congenital ocular colobomata and microphthalmia. Immunohistochemical and in situ hybridization assays reveal that the expression of several regulatory genes essential for early optic vesicle development, including Pax6, Otx2, Mitf, Pax2 and Vax1/2, is altered in the corresponding compartments of the mutant eye. Using ChIP assay, siRNA treatment and transient transfection in ARPE-19 cells in vitro, we demonstrate that Pax6 and Otx2 are directly regulated by COUP-TFs. Taken together, our findings reveal novel and distinct cell-intrinsic mechanisms mediated by COUP-TF genes to direct the specification and differentiation of progenitor cells, and that COUP-TFs are crucial for dorsalization of the eye.
Sequential requirement of Sox4 and Sox11 during development of the sympathetic nervous system
Authors: Potzner Michaela R. , Tsarovina Konstantina , Binder Ellen , Penzo-Méndez Alfredo , Lefebvre Veronique , Rohrer Hermann , Wegner Michael , Sock Elisabeth
Published: February 2010

The highly related transcription factors Sox4 and Sox11 are expressed in the developing sympathetic nervous system. In the mouse, Sox11 appears first, whereas Sox4 is prevalent later. Using mouse mutagenesis and overexpression strategies in chicken, we studied the role of both SoxC proteins in this tissue. Neither Sox4 nor Sox11 predominantly functioned by promoting pan-neuronal or noradrenergic differentiation of sympathetic neurons as might have been expected from studies in neuronal precursors of the central nervous system. The transcriptional network that regulates the differentiation of sympathetic neurons remained intact and expression of noradrenergic markers showed only minor alterations. Instead, Sox11 was required in early sympathetic ganglia for proliferation of tyrosine hydroxylase-expressing cells, whereas Sox4 ensured the survival of these cells at later stages. In the absence of both Sox4 and Sox11, sympathetic ganglia remained hypoplastic throughout embryogenesis because of consecutive proliferation and survival defects. As a consequence, sympathetic ganglia were rudimentary in the adult and sympathetic innervation of target tissues was impaired leading to severe dysautonomia.
Cadherin-7 and cadherin-6B differentially regulate the growth, branching and guidance of cranial motor axons
Authors: Barnes Sarah H. , Price Stephen R. , Wentzel Corinna , Guthrie Sarah C.
Published: February 2010

Cadherin-7 (Cad7) and cadherin-6B (Cad6B) are expressed in early and late phases of cranial motoneuron development, respectively. Cad7 is expressed by cranial motoneurons soon after they are generated, as well as in the environment through which their axons extend. By contrast, Cad6B is expressed by mature cranial motoneurons. We demonstrate in chick that these cadherins play distinct roles in cranial motor axon morphology, branching and projection. Using in vitro approaches, we show that Cad7 enhances motor axon outgrowth, suppresses the formation of multiple axons and restricts interstitial branching, thus promoting the development of a single unbranched axon characteristic of differentiating motoneurons. Conversely, Cad6B in vitro promotes motor axon branching, a characteristic of mature motoneurons. In vivo gain- and loss-of-function experiments for these cadherins yielded phenotypes consistent with this interpretation. In particular, a loss of cadherin-mediated interactions in vivo led to dysregulation of the cranial motoneuron normal branching programme and caused axon navigation defects. We also demonstrate that Cad6B functions via the phosphatidylinositol 3-kinase pathway. Together, these data show that Cad7 and Cad6B differentially regulate cranial motoneuron growth, branching and axon guidance.
Epithelial relaxation mediated by the myosin phosphatase regulator Mypt1 is required for brain ventricle lumen expansion and hindbrain morphogenesis
Authors: Gutzman Jennifer H. , Sive Hazel
Published: February 2010

We demonstrate that in the zebrafish hindbrain, cell shape, rhombomere morphogenesis and, unexpectedly, brain ventricle lumen expansion depend on the contractile state of the neuroepithelium. The hindbrain neural tube opens in a specific sequence, with initial separation along the midline at rhombomere boundaries, subsequent openings within rhombomeres and eventual coalescence of openings into the hindbrain ventricle lumen. A mutation in the myosin phosphatase regulator mypt1 results in a small ventricle due to impaired stretching of the surrounding neuroepithelium. Although initial hindbrain opening remains normal, mypt1 mutant rhombomeres do not undergo normal morphological progression. Three-dimensional reconstruction demonstrates cell shapes within rhombomeres and at rhombomere boundaries are abnormal in mypt1 mutants. Wild-type cell shape requires that surrounding cells are also wild type, whereas mutant cell shape is autonomously regulated. Supporting the requirement for regulation of myosin function during hindbrain morphogenesis, wild-type embryos show dynamic levels of phosphorylated myosin regulatory light chain (pMRLC). By contrast, mutants show continuously high pMRLC levels, with concentration of pMRLC and myosin II at the apical side of the epithelium, and myosin II and actin concentration at rhombomere boundaries. Brain ventricle lumen expansion, rhombomere morphology and cell shape are rescued by inhibition of myosin II function, indicating that each defect is a consequence of overactive myosin. We suggest that the epithelium must `relax', via activity of myosin phosphatase, to allow for normal hindbrain morphogenesis and expansion of the brain ventricular lumen. Epithelial relaxation might be a widespread strategy to facilitate tube inflation in many organs.
FGF signal-dependent segregation of primitive endoderm and epiblast in the mouse blastocyst
Authors: Yamanaka Yojiro , Lanner Fredrik , Rossant Janet
Published: February 2010

Primitive endoderm (PE) and epiblast (EPI) are two lineages derived from the inner cell mass (ICM) of the E3.5 blastocyst. Recent studies showed that EPI and PE progenitors expressing the lineage-specific transcriptional factors Nanog and Gata6, respectively, arise progressively as the ICM develops. Subsequent sorting of the two progenitors during blastocyst maturation results in the ormation of morphologically distinct EPI and PE layers at E4.5. It is, however, unknown how the initial differences between the two populations become established in the E3.5 blastocyst. Because the ICM cells are derived from two distinct rounds of polarized cell divisions during cleavage, a possible role for cell lineage history in promoting EPI versus PE fate has been proposed. We followed cell lineage from the eight-cell stage by live cell tracing and could find no clear linkage between developmental history of individual ICM cells and later cell fate. However, modulating FGF signaling levels by inhibition of the receptor/MAP kinase pathway or by addition of exogenous FGF shifted the fate of ICM cells to become either EPI or PE, respectively. Nanog- or Gata6-expressing progenitors could still be shifted towards the alternative fate by modulating FGF signaling during blastocyst maturation, suggesting that the ICM progenitors are not fully committed to their final fate at the time that initial segregation of gene expression occurs. In conclusion, we propose a model in which stochastic and progressive specification of EPI and PE lineages occurs during maturation of the blastocyst in an FGF/MAP kinase signal-dependent manner.
The PXY-CLE41 receptor ligand pair defines a multifunctional pathway that controls the rate and orientation of vascular cell division
Authors: Etchells J. Peter , Turner Simon R.
Published: February 2010

Controlling the orientation of cell division is fundamental to the development of complex body plans. This is particularly apparent in plants, where development is determined by differential growth that results solely from changes in cell expansion and orientation of the cell division plane. Despite the fundamental importance of cell division orientation to plant development, the mechanisms regulating this process remain almost completely unknown. During vascular development, the meristematic cambial cells divide down their long axis in a highly orientated manner to generate clear files of cells. The receptor kinase PXY has previously be shown to be essential for this orientation. Here, we demonstrate that the division plane is determined by the interactions of PXY and its peptide ligand, CLE41. PXY is expressed within dividing meristematic cells of the procambium, whereas CLE41 localises to the adjacent phloem cells. Altering the pattern of CLE41 expression leads to a loss of cell division orientation and a dramatic loss of ordered vascular tissue development. By contrast, increasing phloem-specific expression of CLE41 results in more cell divisions, but the orientation of cell division is retained, leading to both increased and well-ordered vascular development. We demonstrate that PXY signalling is down-regulated by CLE41. This feedback mechanism is crucial in integrating the different roles of PXY signalling in controlling xylem differentiation, regulating the rate of vascular cell division and determining the orientation of cell division. Parallels with animal systems indicate that localised signalling from adjacent cells is a general mechanism for defining the plane of cell division.
lethal giant larvaeis required with thepargenes for the early polarization of theDrosophilaoocyte
Authors: Fichelson Pierre , Jagut Marlène , Lepanse Sophie , Lepesant Jean-Antoine , Huynh Jean-René
Published: February 2010

Most cell types in an organism show some degree of polarization, which relies on a surprisingly limited number of proteins. The underlying molecular mechanisms depend, however, on the cellular context. Mutual inhibitions between members of the Par genes are proposed to be sufficient to polarize the C. elegans one-cell zygote and the Drosophila oocyte during mid-oogenesis. By contrast, the Par genes interact with cellular junctions and associated complexes to polarize epithelial cells. The Par genes are also required at an early step of Drosophila oogenesis for the maintenance of the oocyte fate and its early polarization. Here we show that the Par genes are not sufficient to polarize the oocyte early and that the activity of the tumor-suppressor gene lethal giant larvae (lgl) is required for the posterior translocation of oocyte-specific proteins, including germline determinants. We also found that Lgl localizes asymmetrically within the oocyte and is excluded from the posterior pole. We further demonstrate that phosphorylation of Par-1, Par-3 (Bazooka) and Lgl is crucial to regulate their activity and localization in vivo and describe, for the first time, adherens junctions located around the ring canals, which link the oocyte to the other cells of the germline cyst. However, null mutations in the DE-cadherin gene, which encodes the main component of the zonula adherens, do not affect the early polarization of the oocyte. We conclude that, despite sharing many similarities with other model systems at the genetic and cellular levels, the polarization of the early oocyte relies on a specific subset of polarity proteins.
giant is a bona fide gap gene in the intermediate germband insect, Oncopeltus fasciatus
Authors: Liu Paul Z. , Patel Nipam H.
Published: February 2010

Drosophila undergoes a form of development termed long germ segmentation, where all segments are specified nearly simultaneously so that by the blastoderm stage, the entire body plan has been determined. This mode of segmentation is evolutionarily derived. Most insects undergo short or intermediate germ segmentation, where only anterior segments are specified early, and posterior segments are sequentially specified during germband elongation. These embryological differences imply that anterior and posterior segments might rely upon different molecular mechanisms. In Drosophila, embryos mutant for giant show a gap in the anterior as well fusions of several abdominal segments. In Tribolium, a short germ beetle, giant is required for segmental identity, but not formation, in gnathal segments and also for segmentation of the entire abdomen. This raises the possibility that giant might not act as a gap gene in short and intermediate germ insects. Oncopeltus fasciatus is an intermediate germ insect that is an outgroup to the clade containing Drosophila and Tribolium. We cloned the Oncopeltus homolog of giant and determined its expression and function during segmentation. We find that Oncopeltus giant is a canonical gap gene in the maxillary and labial segments and also plays a gap-like role in the first four abdominal segments. Our results suggest that giant was a bona fide gap gene in the ancestor of these insects with this role being lost in the lineage leading towards Tribolium. This highlights the conservation of anterior patterning and evolutionary plasticity of the genetic regulation controlling posterior segmentation, even in short and intermediate germ insects.
Isolation and propagation of enteric neural crest progenitor cells from mouse embryonic stem cells and embryos
Authors: Kawaguchi Jitsutaro , Nichols Jennifer , Gierl Mathias S. , Faial Tiago , Smith Austin
Published: February 2010

Neural crest is a source of diverse cell types, including the peripheral nervous system. The transcription factor Sox10 is expressed throughout early neural crest. We exploited Sox10 reporter and selection markers created by homologous recombination to investigate the generation, maintenance and expansion of neural crest progenitors. Sox10-GFP-positive cells are produced transiently from mouse embryonic stem (ES) cells by treatment with retinoic acid in combination with Fgf8b and the cytokine leukaemia inhibitory factor (Lif). We found that expression of Sox10 can be maintained using noggin, Wnt3a, Lif and endothelin (NWLE). ES cell-derived Sox10-GFP-positive cells cultured in NWLE exhibit molecular markers of neural crest progenitors. They differentiate into peripheral neurons in vitro and are able to colonise the enteric network in organotypic gut cultures. Neural crest cells purified from embryos using the Sox10 reporter also survive in NWLE, but progressively succumb to differentiation. We therefore applied selection to eliminate differentiating cells. Sox10-selected cells could be clonally expanded, cryopreserved, and multiplied for over 50 days in adherent culture. They remained neurogenic in vitro and in foetal gut grafts. Generation of neural crest from mouse ES cells opens a new route to the identification and validation of determination factors. Furthermore, the ability to propagate undifferentiated progenitors creates an opportunity for experimental dissection of the stimuli and molecular circu that govern neural crest lineage progression. Finally, the demonstration of robust enteric neurogenesis provides a system for investigating and modelling cell therapeutic approaches to neurocristopathies such as Hirschsprung's disease.
Regulated increase in folding capacity prevents unfolded protein stress in the ER
Authors: Christis Chantal , Fullaondo Asier , Schildknegt Danny , Mkrtchian Souren , Heck Albert J. R. , Braakman Ineke
Published: February 2010

Stimulation of thyrocytes with thyroid stimulating hormone (TSH) leads to a morphological change and a massive increase in thyroglobulin (Tg) production. Although Tg is a demanding client of the endoplasmic reticulum (ER), its increase did not result in significant accumulation of unfolded protein in the ER. Instead, ER chaperones and folding enzymes reached maximum synthesis rates immediately after TSH stimulation, before significant upregulation of Tg synthesis. The resulting increase in folding capacity before client protein production prevented cellular unfolded-protein stress, confirmed by the silence of the most conserved branch of the unfolded protein response. Thyrocytes set an example of physiological adaptation of cells to a future potentially stress-causing situation, which suggests a general strategy for both non-secretory and specialized secretory cells.
Integrins stimulate E-cadherin-mediated intercellular adhesion by regulating Src-kinase activation and actomyosin contractility
Authors: Martinez-Rico Clara , Pincet Frederic , Thiery Jean-Paul , Dufour Sylvie
Published: February 2010

Cadherins and integrins are major adhesion molecules regulating cell-cell and cell-matrix interactions. In vitro and in vivo studies have demonstrated the existence of crosstalk between integrins and cadherins in cell adhesion and motility. We used a dual pipette assay to measure the force required to separate E-cadherin-producing cell doublets and to investigate the role of integrin in regulating the strength of intercellular adhesion. A greater force was required to separate cell doublets bound to fibronectin or vitronectin-coated beads than for doublets bound to polylysine-coated beads. This effect depended on cell spreading and the duration of stimulation. Cells expressing type II cadherin-7 also responded to fibronectin stimulation to produce a higher intercellular adhesion. Establishment of cadherin-mediated adhesion needed ROCK, MLCK and myosin ATPase II activity. The regulation of intercellular adhesion strength by integrin stimulation required activation of Src family kinases, ROCK and actomyosin contractility. These findings highlight the importance and mechanisms of molecular crosstalk between cadherins and integrins in the control of cell plasticity during histogenesis and morphogenesis.
Control of mitotic and meiotic centriole duplication by the Plk4-related kinase ZYG-1
Authors: Peters Nathaniel , Perez Dahlia E. , Song Mi Hye , Liu Yan , Müller-Reichert Thomas , Caron Cathy , Kemphues Kenneth J. , O'Connell Kevin F.
Published: February 2010

Centriole duplication is of crucial importance during both mitotic and male meiotic divisions, but it is currently not known whether this process is regulated differently during the two modes of division. In Caenorhabditis elegans, the kinase ZYG-1 plays an essential role in both mitotic and meiotic centriole duplication. We have found that the C-terminus of ZYG-1 is necessary and sufficient for targeting to centrosomes and is important for differentiating mitotic and meiotic centriole duplication. Small truncations of the C-terminus dramatically lower the level of ZYG-1 at mitotic centrosomes but have little effect on the level of ZYG-1 at meiotic centrosomes. Interestingly, truncation of ZYG-1 blocks centrosome duplication in the mitotic cycle but leads to centrosome amplification in the meiotic cycle. Meiotic centriole amplification appears to result from the overduplication of centrioles during meiosis I and leads to the formation of multipolar meiosis II spindles. The extra centrioles also disrupt spermatogenesis by inducing the formation of supernumerary fertilization-competent spermatids that contain abnormal numbers of chromosomes and centrioles. Our data reveal differences in the regulation of mitotic and meiotic centrosome duplication, particularly with regard to ZYG-1 activity, and reveal an important role for centrosomes in spermatid formation.
Drosophila Klp67A binds prophase kinetochores to subsequently regulate congression and spindle length
Authors: Savoian Matthew S. , Glover David M.
Published: February 2010

The kinesin-8 proteins are a family of microtubule-depolymerising motor molecules, which, despite their highly conserved roles in chromosome alignment and spindle dynamics, remain poorly characterised. Here, we report that the Drosophila kinesin-8 protein, Klp67A, exists in two spatially and functionally separable metaphase pools: at kinetochores and along the spindle. Fixed and live-cell analyses of different Klp67A recombinant variants indicate that this kinesin-8 first collects at kinetochores during prophase and, by metaphase, localises to the kinetochore outerplate. Although the catalytic motor activity of Klp67A is required for efficient kinetochore recruitment at all times, microtubules are entirely dispensable for this process. The tail of Klp67A does not play a role in kinetochore accumulation, but is both necessary and sufficient for spindle association. Using functional assays, we reveal that chromosome position and spindle length are determined by the microtubule-depolymerising motor activity of Klp67A exclusively when located at kinetochores, but not along the spindle. These data reveal that, unlike other metazoan kinesin-8 proteins, Klp67A binds the nascent prophase and mature metaphase kinetochore. From this location, Klp67A uses its motor activity to ensure chromosome alignment and proper spindle length.
Centromere DNA decatenation depends on cohesin removal and is required for mammalian cell division
Authors: Wang Lily Hui-Ching , Mayer Bernd , Stemmann Olaf , Nigg Erich A.
Published: February 2010

Sister chromatid cohesion is mediated by DNA catenation and proteinaceous cohesin complexes. The recent visualization of PICH (Plk1-interacting checkpoint helicase)-coated DNA threads in anaphase cells raises new questions as to the role of DNA catenation and its regulation in time and space. In the present study we show that persistent DNA catenation induced by inhibition of Topoisomerase-IIα can contribute to sister chromatid cohesion in the absence of cohesin complexes and that resolution of catenation is essential for abscission. Furthermore, we use an in vitro chromatid separation assay to investigate the temporal and functional relationship between cohesin removal and Topoisomerase-IIα-mediated decatenation. Our data suggest that centromere decatenation can occur only after separase activation and cohesin removal, providing a plausible explanation for the persistence of centromere threads after anaphase onset.
Fission yeast TORC1 regulates phosphorylation of ribosomal S6 proteins in response to nutrients and its activity is inhibited by rapamycin
Authors: Nakashima Akio , Sato Tatsuhiro , Tamanoi Fuyuhiko
Published: February 2010

Cellular activities are regulated by environmental stimuli through protein phosphorylation. Target of rapamycin (TOR), a serine/threonine kinase, plays pivotal roles in cell proliferation and cell growth in response to nutrient status. In Schizosaccharomyces pombe, TORC1, which contains Tor2, plays crucial roles in nutrient response. Here we find a nitrogen-regulated phosphoprotein, p27, in S. pombe using the phospho-Akt substrate antibody. Response of p27 phosphorylation to nitrogen availability is mediated by TORC1 and the TSC-Rhb1 signaling, but not by TORC2 or other nutrient stress-related pathways. Database and biochemical analyses indicate that p27 is identical to ribosomal protein S6 (Rps6). Ser235 and Ser236 in Rps6 are necessary for Rps6 phosphorylation by TORC1. These Rps6 phosphorylations are dispensable for cell viability. Rps6 phosphorylation by TORC1 also responds to availability of glucose and is inhibited by osmotic and oxidative stresses. Rapamycin inhibits the ability of TORC1 to phosphorylate Rps6, owing to interaction of the rapamycin-FKBP12 complex with the FRB domain in Tor2. Rapamycin also leads to a decrease in cell size in a TORC1-dependent manner. Our findings demonstrate that the nutrient-responsive and rapamycin-sensitive TORC1-S6 signaling exists in S. pombe, and that this pathway plays a role in cell size control.
Microtubule assembly by the Apc protein is regulated by importin-β—RanGTP
Authors: Dikovskaya Dina , Li Zhuoyu , Newton Ian P. , Davidson Iain , Hutchins James R. A. , Kalab Petr , Clarke Paul R. , Näthke Inke S.
Published: February 2010

Mutations in the tumour suppressor Adenomatous polyposis coli (Apc) initiate most sporadic colorectal cancers. Apc is implicated in regulating microtubule (MT) dynamics in interphase and mitosis. However, little is known about the underlying mechanism or regulation of this Apc function. We identified importin-β as a binding partner of Apc that regulates its effect on MTs. Apc binds importin-β in vitro and in Xenopus egg extracts, and RanGTP inhibits this interaction. The armadillo-like repeat domain of importin-β binds to the middle of Apc, where it can compete with β-catenin. In addition, two independent sites in the C terminus of Apc bind the N-terminal region of importin-β. Binding to importin-β reduces the ability of Apc to assemble and bundle MTs in vitro and to promote assembly of microtubule asters in Xenopus egg extracts, but does not affect the binding of Apc to MTs or to EB1. Depletion of Apc decreases the formation of cold-stable spindles in Xenopus egg extracts. Importantly, the ability of purified Apc to rescue this phenotype was reduced when it was constitutively bound to importin-β. Thus, importin-β binds to Apc and negatively regulates the MT-assembly and spindle-promoting activity of Apc in a Ran-regulatable manner.
Investigation of the potential association of vitamin D binding protein with lipoproteins
Authors: Speeckaert Marijn M , Taes Youri E , De Buyzere Marc L , Christophe Armand B , Kaufman Jean-Marc , Delanghe Joris R
Published: February 2010

Background

Vitamin D binding protein (DBP) acts as a vitamin D carrier and an actin scavenger. We have previously reported a correlation between serum DBP and lipid parameters in a cystic fibrosis population. In the present study, the relationship between serum DBP, lipoprotein fractions and vitamin D is investigated.

Methods

The presence of DBP in lipoprotein fractions was examined using precipitation, gel permeation chromatography and ultracentrifugation. The association between DBP and lipids was investigated in a cohort study of 211 men. Total and actin-free DBP concentrations were assessed by immunonephelometry and enzyme-linked immunosorbent assay. Serum 25(OH)- and 1.25(OH)2-vitamin D3 were assayed by radioimmunoassay. Total cholesterol, high-density lipoprotein cholesterol (HDL), triglycerides and insulin were measured using routine methods. Low-density lipoprotein-cholesterol (LDL) was calculated according to Friedewald's formula.

Results

DBP was found to be present in very-low-density lipoprotein (VLDL). Gel permeation chromatography revealed a bimodal DBP distribution with a lipid-bound fraction besides the known free fraction. Ultracentrifugation confirmed the presence of DBP and 25(OH)-vitamin D3 in the VLDL particle. Total serum DBP concentration and the actin-bound DBP/DBP ratio correlated significantly with total cholesterol, LDL-cholesterol, triglycerides and albumin. The 25(OH)-vitamin D3/DBP ratio correlated negatively with serum triglyceride concentration and body mass index (BMI). The actin-bound DBP complex was identified with Western blot.

Conclusions

The lipid-bound DBP fraction may be of greater importance than initially thought. The present findings may have clinical consequences in view of the important physiological role of DBP.
Biochemical risk factors for stone formation in a Scottish paediatric hospital population
Authors: MacDougall Lyndsey , Taheri Sepideh , Crofton Patricia
Published: February 2010

Background

Renal stones in children, although rare, may be associated with morbidity and renal damage. Scottish children have a different ethnic composition and diet compared with paediatric populations previously studied. Urinary stone promoters include calcium, oxalate and urate. Postulated inhibitors include citrate and glycosaminoglycans (GAGs). We tested the hypothesis that Scottish paediatric stone-formers have higher excretion of urinary stone promoters (calcium/oxalate/urate) and/or lower excretion of stone inhibitors (citrate/GAGs) than children with isolated haematuria and controls.

Methods

In this case-controlled study, we measured creatinine, calcium, oxalate, urate, citrate and GAGs in random urine samples from 24 stone-formers (excluding inherited metabolic disorders), median age 10.2 (range 1.0–17.2) y; 25 patients with isolated haematuria, 6.3 (0.6–13.7) y; and 32 controls, 7.5 (0.8–14.7) y.

Results

Excretion of urinary promoters and inhibitors differed among stone-formers, haematuria and control groups for (median (range)): calcium (0.82 (0.02–2.19), 0.43 (0.08–2.65), 0.31 (0.04–2.12) mmol/mmol creatinine, respectively, P = 0.005), citrate (0.42 (0.13–0.72), 0.33 (0.05–0.84), 0.61 (0.11–1.75) mmol/mmol creatinine, P = 0.001), calcium:citrate ratio (1.68 (0.19–4.81), 1.30 (0.19–9.57), 0.54 (0.10–2.27) mmol/mmol, P < 0.0001) and the promoter:inhibitor ratio (calcium × oxalate)/(citrate × GAGs) (8.3 (1.0–82.5), 4.3 (1.2–69.5), 2.8 (0.3–13.2) mmol/g, P < 0.0001).

Conclusions

Scottish paediatric stone-formers had lower urinary citrate excretion and higher urinary calcium excretion, calcium:citrate ratio and promoter:inhibitor ratio compared with controls. Urinary calcium excretion and promoter:inhibitor ratio was also higher than children with isolated haematuria. Nevertheless, marked overlap between the stone-former and haematuria groups for promoter:inhibitor and calcium:citrate ratios suggests that some patients with isolated haematuria may be at future risk of urolithiasis.
Shortness of breath: flushing out the diagnosis
Authors: Sulaiman Raashda , Panting Mark , Bhogal Gurpal , Perry Ian , Ford Clare , Gama Rousseau
Published: February 2010

We report a 63-year-old man who presented with breathlessness and weight loss and was diagnosed on echocardiography to have carcinoid heart disease. It was later transpired that he underwent surgical removal of an ileal carcinoid tumour 19 years previously.
Imprecision of tumour biomarker measurements on Roche Modular E170 platform fulfills desirable goals derived from biological variation
Authors: Dolci Alberto , Scapellato Luisa , Mozzi Roberta , Panteghini Mauro
Published: February 2010

Background

Monitoring of test imprecision is one of the most important quality indicators in clinical laboratories. Imprecision goals should be derived from biological variation. The aim of this study was to evaluate the imprecision of eight tumour biomarker assays routinely measured on the Modular E170 system.

Methods

Method coefficient of variations (CVs) were obtained by an appropriate Internal Quality Control programme based on the measurement every working day of a fresh–frozen human serum pool with biomarkers concentrations around the clinical cut-offs. We evaluated data collected along the whole year 2008 ( n range: 21–461); monthly CVs and their cumulative means were calculated and compared with corresponding goals.

Results

Biomarkers concentration means and average yearly CVs (desirable goals in parentheses) were as follows: α-fetoprotein, 9.6 μg/L, 3.9% (6.0%); CA125, 41.2 U/L, 2.8% (12.4%); CA15.3, 32.7 U/L, 3.1% (3.1%); CA19.9, 35.1 U/L, 2.8% (8.0%); CEA, 7.7 μg/L, 4.3% (6.4%); prostate-specific antigen (PSA), 4.1 μg/L, 4.3% (9.1%); CYFRA 21.1, 2.4 μg/L, 5.7% (11.3%); and ferritin, 64.5 μg/L, 4.0% (7.1%).

Conclusions

Our study shows that in routine laboratory practice and over a clinically and analytically relevant time-span, the imprecision of the tumour biomarker measurements on the Roche Modular E170 fulfills desirable goals. For four assays (CA125, CA19.9, PSA and CYFRA 21.1) the optimum CV can even be achieved.
Effect of transport temperature on the Scantibodies total intact parathyroid hormone immunoradiometric assay using the RIAMAT-280
Authors: Plancha-Mansanet Ma Carmen , Félix-Fontestad Jesús , Caballero-Calabuig Elisa , Reyes-Ojeda Ma Dolores , Abreu-Sánchez Pedro , Sopena-Novales Pablo , Martínez-Sanchís Begoña
Published: February 2010

Background

Inadequate temperature affects the stability of intact parathyroid hormone (i-PTH) kits. Room temperature during transport modifies i-PTH results.

Method

Percent bound (%B/Bmax) and concentrations (pmol/L) of standards, controls (C1, C2) and pool from eight standard curves were divided into: group I (three curves from kits kept at room temperature for more than 48 h) and group II (five curves from kits kept at 2–8°C) during transport. i-PTH was measured using Scantibodies total i-PTH assay with RIAMAT-280.

Results

%B/Bmax for standards, C1 and C2 were significantly higher in group I versus II ( P = 0.04). %B/Bmax for the pool were significantly lower in group I ( P = 0.001). i-PTH pool concentration in group I was 51% lower (95% confidence interval, 47–53%, P = 0.001); differences were not significant for C1 ( P = 0.25) and C2 ( P = 0.57) in both groups.

Conclusion

Room temperature on i-PTH kit during transport alters the standard curve, resulting in a decrease in i-PTH. Using a pool as internal quality control allows the detection of these changes not detected by kit controls.
Automated assay for determining cellular cholesterol using a random access chemistry analyser
Authors: Tada Satoshi , Kitanaka Akira , Kubota Yoshitsugu , Ito Mitsuru , Taminato Tomohiko
Published: February 2010

Background

We have previously reported an ultrasensitive fluorometric assay for measuring cellular cholesterol. Although this technique is reliable, the use of the assay has limitations due to the requirement for special equipment. It is therefore difficult to apply this assay for the routine determination of cellular cholesterol.

Methods

A colorimetric assay to measure cellular cholesterol was established that utilizes reagents widely used for the measurement of cholesterol in blood samples in conjunction with a random access chemistry analyser ARCHITECT c8000 that is also common in clinical laboratories.

Results

This colorimetric assay showed excellent linearity and recovery. The within-run coefficients of variation were less than 2.5%. The sensitivity of this method, with its detection limit of 1.29 μmol/L, was found to be superior to that of the fluorometric assay we have developed previously. In platelets obtained from patients with diabetes, both the free cholesterol and cholesterol ester content were significantly increased.

Conclusions

Using this technique, measurement of cellular cholesterol could be performed routinely without the requirement for special reagents and equipment.
Plasticity of the RNA kink turn structural motif
Authors: Antonioli Alexandra H. , Cochrane Jesse C. , Lipchock Sarah V. , Strobel Scott A.
Published: February 2010

The kink turn (K-turn) is an RNA structural motif found in many biologically significant RNAs. While most examples of the K-turn have a similar fold, the crystal structure of the Azoarcus group I intron revealed a novel RNA conformation, a reverse kink turn bent in the direction opposite that of a consensus K-turn. The reverse K-turn is bent toward the major grooves rather than the minor grooves of the flanking helices, yet the sequence differs from the K-turn consensus by only a single nucleotide. Here we demonstrate that the reverse bend direction is not solely defined by internal sequence elements, but is instead affected by structural elements external to the K-turn. It bends toward the major groove under the direction of a tetraloop–tetraloop receptor. The ability of one sequence to form two distinct structures demonstrates the inherent plasticity of the K-turn sequence. Such plasticity suggests that the K-turn is not a primary element in RNA folding, but instead is shaped by other structural elements within the RNA or ribonucleoprotein assembly.
Pathologic Findings in Novel Influenza A (H1N1) Virus (“Swine Flu”) Infection
Authors: Mukhopadhyay Sanjay , Philip Abraham T. , Stoppacher Robert
Published: February 2010

Although novel influenza A (H1N1) virus infection has assumed pandemic proportions, there are few reports of the pathologic findings. Herein we describe the pathologic findings of novel influenza A (H1N1) infection based on findings in 2 autopsy cases. The first patient, a 36-year-old man, had flu-like symptoms; oseltamivir (Tamiflu) therapy was started 8 days after onset of symptoms, and he died on day 15 of his illness. At autopsy, the main finding was diffuse alveolar damage with extensive fresh intra-alveolar hemorrhage. The second patient, a 46-year-old woman with alcoholism, was found unresponsive in a basement and brought to the hospital intoxicated and confused. Her condition deteriorated rapidly, and she died 4 days after admission. The main autopsy finding was acute bronchopneumonia with gram-positive cocci, intermixed with diffuse alveolar damage. The pathologic findings in these contrasting cases of novel influenza A (H1N1) infection are similar to those previously described for seasonal influenza. The main pathologic abnormality in fatal cases is diffuse alveolar damage, but it may be overshadowed by an acute bacterial bronchopneumonia.
Decay resistance of wood treated with fluorinated waterproofing agents
Authors: Iaych Kamal , Pabon Martial , Gérardin Christine , Gérardin Philippe
Published: February 2010

No abstract available
Interaction of dissolved and colloidal material during the mixing of different pulps
Authors: Monte M. Concepcion , MacNeil Donald , Negro Carlos , Blanco Angeles
Published: February 2010

Mixtures of stickies-containing and stickies-free pulps were investigated for their deposition potential in an attempt to better understand the interactions of dissolved and colloidal material (DCM) when mixing two different pulps. The filtered pulp mixtures were tested in a deposition apparatus which measures both the dynamic fluid as well as impact deposition by an established optical scanning method. A pulp filtrate of model stickies led to deposition according to the proportion of stickies-containing pulp in the mixture. Other mixtures of pulps, however, led to deposition that differed from the predicted value. It is theorised that pulp fibres present in the mixture could adsorb the polysaccharides that would otherwise keep the colloidal system electrostatically stable. This destabilisation was most prominent at lower proportions of the stickies-free pulp suspensions used for mixing. These results show that care must be taken when mixing different pulps for paper and board production, as even a small amount of replacement pulp can lead to destabilisation of DCM and formation of deposits. Furthermore, special care must be taken when mixtures of pulps are used to validate stickies measurements.
Growth of ZnO nanofilms on wood with improved photostability
Authors: Yu Yan , Jiang Zehui , Wang Ge , Song Ye
Published: February 2010

A major drawback of wood in outdoor exposure is photodegradation of the surface. Nano zinc oxide (ZnO) has been reported to provide enhanced stability of wood against UV degradation. In this study, the formation of ZnO nanostructures on the surface of solid wood was achieved via a simple two-step process consisting of generation of ZnO seeds on the wood surface followed by a solution treatment to promote crystal growth. The morphology and chemical composition of the ZnO films was studied by field-emission scanning electron microscopy combined with energy dispersive X-ray and X-ray diffraction. Accelerated weathering was used to evaluate the photostability of treated wood. The morphology of ZnO nanofilm was dependent on the exposure time in the ZnO seeding solution. Greatly enhanced photostability was achieved with treated wood. UV stability was partially dependent on crystal morphology. This two-step method could probably also be employed to treat other biomaterials with rough surfaces such as bamboo.
Termite-resistant heartwood. Effect of antioxidants on termite feeding deterrence and mortality
Authors: Little Nathan S. , Schultz Tor P. , Nicholas Darrel D.
Published: February 2010

Biocides currently employed to prevent termite damage face environmental and toxicity concerns. We recently proposed that heartwood which is naturally resistant to termites might be due to the extractives having both toxicity and antioxidant properties and we reported that the artificial and benign antioxidant butylated hydroxytoluene (BHT) had termite feeding deterrence and toxicity properties. Here, we investigate other antioxidants, both natural and synthetic, and analogs which lack antioxidant properties, on Reticulitermes flavipes Kollar. Laboratory no-choice tests according to AWPA Standard E1 were performed. Antioxidants that are benign to humans had feeding deterrence and mortality properties to R. flavipes. Conversely, the non-antioxidant analogs, with the exception of the heterocyclic flavanone which was previously shown to be active against decay fungi, had little effect on R. flavipes. We conclude that R. flavipes avoids wood which contain high levels of antioxidants, such as heartwood with phenolic extractives.
Kraft pulping of wood treated with carbon-based preservatives
Authors: Stirling Rod , Bicho Paul , Daniels Bob , Morris Paul I.
Published: February 2010

No abstract available
Automated measurement of vessel properties in birch and poplar wood
Authors: Chen Fang Fiona , Evans Robert
Published: February 2010

A method is proposed for the automated quantitative analysis of vessel characteristics in birch and poplar species. The method combines image-processing techniques with robust statistical approaches for automatically identifying vessels from digital microscopy images obtained by transmitted red light. The proposed method has been tested over a wide range of birch and poplar samples from different growth environments. Performance of the automatic vessel identification routine was assessed using results obtained by manual counting. The automated method produced fast and reliable vessel measurements and was robust to variations within and between samples. The approach has been merged into the wood property measurement system SilviScan as a core component of the hardwood analysis set for research and commercial use.
The Guanine Exchange FactorvavControls Axon Growth and Guidance duringDrosophilaDevelopment
Authors: Malartre Marianne , Ayaz Derya , Amador Fatima Fernandez , Martín-Bermudo Maria Dolores
Published: February 2010

The Vav proteins are guanine exchange factors (GEFs) that trigger the activation of the Rho GTPases in general and the Rac family in particular. While the role of the mammalianvavgenes has been extensively studied in the hematopoietic system and the immune response, there is little information regarding the role ofvavoutside of these systems. Here, we report that the singleDrosophila vavhomolog is ubiquitously expressed during development, although it is enriched along the embryonic ventral midline and in the larval eye discs and brain. We have analyzed the role thatvavplays during development by generatingDrosophilanull mutant alleles. Our results indicate thatvavis required during embryogenesis to prevent longitudinal axons from crossing the midline. Later on, during larval development,vavis required within the axons to regulate photoreceptor axon targeting to the optic lobe. Finally, we demonstrate that adultvavmutant escapers, which exhibit coordination problems, display axon growth defects in the ellipsoid body, a brain area associated with locomotion control. In addition, we show thatvavinteracts with other GEFs known to act downstream of guidance receptors. Thus, we propose thatvavacts in coordination with other GEFs to regulate axon growth and guidance during development by linking guidance signals to the cytoskeleton via the modulation of Rac activity.
Perisomatic Voltage-Gated Sodium Channels Actively Maintain Linear Synaptic Integration in Principal Neurons of the Medial Superior Olive
Authors: Scott Luisa L. , Mathews Paul J. , Golding Nace L.
Published: February 2010

Principal neurons of the medial superior olive (MSO) compute azimuthal sound location by integrating phase-locked inputs from each ear. While previous experimental and modeling studies have proposed that voltage-gated sodium channels (VGSCs) play an important role in synaptic integration in the MSO, these studies appear at odds with the unusually weak active backpropagation of action potentials into the soma and dendrites. To understand the spatial localization and biophysical properties of VGSCs, we isolated sodium currents in MSO principal neurons in gerbil brainstem slices. Nucleated and cell-attached patches revealed that VGSC density at the soma is comparable to that of many other neuron types, but channel expression is largely absent from the dendrites. Further, while somatic VGSCs activated with conventional voltage dependence (V1/2= −30 mV), they exhibited an unusually negative range of steady-state inactivation (V1/2= −77 mV), leaving ∼92% of VGSCs inactivated at the resting potential (approximately −58 mV). In current-clamp experiments, non-inactivated VGSCs were sufficient to amplify subthreshold EPSPs near action potential threshold, counterbalancing the suppression of EPSP peaks by low voltage-activated potassium channels. EPSP amplification was restricted to the perisomatic region of the neuron, and relatively insensitive to preceding inhibition. Finally, computational modeling showed that the exclusion of VGSCs from the dendrites equalizes somatic EPSP amplification across synaptic locations and lowered the threshold for bilateral versus unilateral excitatory synaptic inputs. Together, these findings suggest that the pattern of sodium channel expression in MSO neurons contributes to these neurons' selectivity for coincident binaural inputs.
Subcortical Representation of Non-Fourier Image Features
Authors: Rosenberg Ari , Husson T. Robert , Issa Naoum P.
Published: February 2010

A fundamental goal of visual neuroscience is to identify the neural pathways representing different image features. It is widely argued that the early stages of these pathways represent linear features of the visual scene and that the nonlinearities necessary to represent complex visual patterns are introduced later in cortex. We tested this by comparing the responses of subcortical and cortical neurons to interference patterns constructed by summing sinusoidal gratings. Although a linear mechanism can detect the component gratings, a nonlinear mechanism is required to detect an interference pattern resulting from their sum. Consistent within vitroretinal ganglion cell recordings, we found that interference patterns are represented subcortically by cat LGN Y-cells, but not X-cells. Linear and nonlinear tuning properties of LGN Y-cells were then characterized and compared quantitatively with those of cortical area 18 neurons responsive to interference patterns. This comparison revealed a high degree of similarity between the two neural populations, including the following: (1) the representation of similar spatial frequencies in both their linear and nonlinear responses, (2) comparable orientation selectivity for the high spatial frequency carrier of interference patterns, and (3) the same difference in their temporal frequency selectivity for drifting gratings versus the envelope of interference patterns. The present findings demonstrate that the nonlinear subcortical Y-cell pathway represents complex visual patterns and likely underlies cortical responses to interference patterns. We suggest that linear and nonlinear mechanisms important for encoding visual scenes emerge in parallel through distinct pathways originating at the retina.