julilili42/papers huggingface dataset:
FACKEL is a sterol C-14 reductase required for organized cell division and expansion in Arabidopsis embryogenesis
2000-06-15

In flowering plants, the developing embryo consists of growing populations of cells whose fates are determined in a position-dependent manner to form the adult organism. Mutations in the FACKEL ( FK ) gene affect body organization of the Arabidopsis seedling. We report that FK is required for cell division and expansion and is involved in proper organization of the embryo. We isolated FK by positional cloning. Expression analysis in embryos revealed that FK mRNA becomes localized to meristematic zones. FK encodes a predicted integral membrane protein related to the vertebrate lamin B receptor and sterol reductases across species, including yeast sterol C-14 reductase ERG24. We provide functional evidence that FK encodes a sterol C-14 reductase by complementation of erg24 . GC/MS analysis confirmed that fk mutations lead to accumulation of intermediates in the biosynthetic pathway preceding the C-14 reductase step. Although fk represents a sterol biosynthetic mutant, the phenotype was not rescued by feeding with brassinosteroids (BRs), the only plant sterol signaling molecules known so far. We propose that synthesis of sterol signals in addition to BRs is important in mediating regulated cell growth and organization during embryonic development. Our results indicate a novel role for sterols in the embryogenesis of plants.
Synthesis of Medium-Sized Rings by the Ring-Closing Metathesis Reaction
2000-06-16

Conformational constraints are the keys for the efficient synthesis of medium-sized rings by ring-closing olefin metathesis (RCM). While the RCM reaction has already proved itself in the synthesis of the larger macrocycles, like that found in epothilone, only recently has this reaction been increasingly used in the construction of eight- to ten-membered carbo- and heterocycles. In the picture, a cyclopentane ring ensures the conformational constraints necessary for a successful cyclization.
Monte Carlo dose computation for IMRT optimization*
2000-06-26

A method which combines the accuracy of Monte Carlo dose calculation with a finite size pencil-beam based intensity modulation optimization is presented. The pencil-beam algorithm is employed to compute the fluence element updates for a converging sequence of Monte Carlo dose distributions. The combination is shown to improve results over the pencil-beam based optimization in a lung tumour case and a head and neck case. Inhomogeneity effects like a broader penumbra and dose build-up regions can be compensated for by intensity modulation.
Indentation Induced t‐ and m‐Phase Orientation in ZrO 2
2000-06-27

The structural changes in the vicinity of indentations in Y-PSZ were investigated by microraman spectroscopy and micro-focus synchroton radiation diffraction. It is shown that some Raman band intensities are strongly susceptible to the orientation relative to a polarised laser beam, both for monoclinic and tetragonal phase bands. This feature was used to demonstrate a preferred orientation of both t- and m-grains around indentations. The orientation direction rotates along the edges of an indent, which is related to the curvature of stress field lines. This feature is also important for the evaluation of relative proportions of t- and m-phase in partially transformed ZrO2 and is a potential source for large errors.
Label-Free Biochemical Detection Coupled On-Line to Liquid Chromatography
2000-06-29

The on-line coupling of a label-free optical biosensor to a HPLC system is described by combining the separation power of HPLC with the specificity of the biosensor system. A highly cross-reactive antibody against the pesticide isoproturon was used as model for affinity proteins. The binding strength of the antibody to the utilized pesticides was characterized with the biosensor, first. In the on-line coupling setup, the eluate of the HPLC was mixed continuously with the antibodies. The presence of antigens was detected by a reduction of the antibody binding to the transducer. This reduced binding was quantified by a differentiation of the sensor signal by applying a Savitzky-Golay algorithm. Limits of detection were found to be in the femtomole range without preconcentration, which is comparable to a study using fluorescence-based biochemical detection.
SUT2, a Putative Sucrose Sensor in Sieve Elements
2000-07-01

In leaves, sucrose uptake kinetics involve high- and low-affinity components. A family of low- and high-affinity sucrose transporters (SUT) was identified. SUT1 serves as a high-affinity transporter essential for phloem loading and long-distance transport in solanaceous species. SUT4 is a low-affinity transporter with an expression pattern overlapping that of SUT1. Both SUT1 and SUT4 localize to enucleate sieve elements of tomato. New sucrose transporter-like proteins, named SUT2, from tomato and Arabidopsis contain extended cytoplasmic domains, thus structurally resembling the yeast sugar sensors SNF3 and RGT2. Features common to these sensors are low codon bias, environment of the start codon, low expression, and lack of detectable transport activity. In contrast to LeSUT1, which is induced during the sink-to-source transition of leaves, SUT2 is more highly expressed in sink than in source leaves and is inducible by sucrose. LeSUT2 protein colocalizes with the low- and high-affinity sucrose transporters in sieve elements of tomato petioles, indicating that multiple SUT mRNAs or proteins travel from companion cells to enucleate sieve elements. The SUT2 gene maps on chromosome V of potato and is linked to a major quantitative trait locus for tuber starch content and yield. Thus, the putative sugar sensor identified colocalizes with two other sucrose transporters, differs from them in kinetic properties, and potentially regulates the relative activity of low- and high-affinity sucrose transport into sieve elements.
A microarray enzyme-linked immunosorbent assay for autoimmune diagnostics
2000-07-01

In order to quantify autoantibodies in the sera of patients with autoimmune disease, we have created a microarray-based immunoassay that allows the simultaneous analysis of 18 known autoantigens. The microarrays contain serial dilutions of the various antigens, thereby allowing accurate determination of autoantibody titer using minimal amounts of serum. The assay is very sensitive and highly specific: as little as 40 fg of a known protein standard can be detected with little or no cross-reactivity to nonspecific proteins. The signal intensities observed from serial dilutions of immobilized antigen correlate well with serial dilutions of autoimmune sera. Miniaturized and highly parallelized immunoassays like these will reduce costs by decreasing reagent consumption and improve efficiency by greatly increasing the number of assays that can be performed with a single serum sample. This system will significantly facilitate and accelerate the diagnostics of autoimmune diseases and can be adapted easily to any other kind of immunoassay.
Low Interleukin-12 Activity in SeverePlasmodium falciparumMalaria
2000-07-01

ABSTRACT We compared interleukin-12 (IL-12) and other cytokine activities during and after an acute clinical episode in a matched-pair case-control study of young African children who presented with either mild or severe Plasmodium falciparum malaria. The acute-phase, pretreatment plasma IL-12 and alpha interferon (IFN-α) levels, as well as the acute-phase mitogen-stimulated whole-blood production capacity of IL-12, were significantly lower in children with severe rather than mild malaria. IL-12 levels, in addition, showed strong inverse correlations both with parasitemia and with the numbers of circulating malaria pigment-containing neutrophils. Acute-phase plasma tumor necrosis factor (TNF) and IL-10 levels were significantly higher in those with severe malaria, and the concentrations of both of these cytokines were positively correlated both with parasitemia and with the numbers of pigment-containing phagocytes in the blood. Children with severe anemia had the highest levels of TNF in plasma. In all the children, the levels in plasma and production capacities of all cytokines normalized when they were healthy and parasite free. The results indicate that severe but not mild P. falciparum malaria in young, nonimmune African children is characterized by down-regulated IL-12 activity, contrasting markedly with the up-regulation of both TNF and IL-10 in the same children. A combination of disturbed phagocyte functions resulting from hemozoin consumption, along with reduced IFN-γ responses, may contribute to these differential effects.
The Human 26 S and 20 S Proteasomes Generate Overlapping but Different Sets of Peptide Fragments from a Model Protein Substrate
2000-07-01

Intracellular protein degradation is a major source of short antigenic peptides that can be presented on the cell surface in the context of major histocompatibility class I molecules for recognition by cytotoxic T lymphocytes. The capacity of the most important cytosolic protease, the 20 S proteasome, to generate peptide fragments with an average length of 7-8 amino acid residues has been thoroughly investigated. It has been shown that the cleavage products are not randomly generated, but originate from the commitment of the catalytically active subunits to complex recognition motifs in the primary amino acid sequence. The role of the even larger 26 S proteasome is less well defined, however. It has been demonstrated that the 26 S proteasome can bind and degrade ubiquitin-tagged proteins and minigene translation products in vivo and in vitro, but the nature of the degradation products remains elusive. In this study, we present the first analysis of cleavage products from in vitro digestion of the unmodified model substrate beta-casein with both the 26 S and 20 S proteasome. The data we obtained show that 26 S and 20 S proteasomes generate overlapping, but at the same time substantially different, sets of fragments by following very similar instructions.
The southern Menderes Massif (western Turkey): geochronology and exhumation history
2000-07-01

Abstract In the southern flank of the Menderes Massif, western Turkey, an E–W‐trending quartz–mica vein was recognized in the augen gneisses of the so‐called ‘core’ series. Rb‐Sr determinations of two undeformed or slightly deformed mica books from the vein yielded Palaeocene–Early Eocene ages ( c . 62–43 Ma) for the vein formation. The new data are interpreted to closely post‐date the time of major Barrovian‐type High Temperature/Medium Pressure (HT/MP) main Menderes metamorphism (MMM) and coeval crustal‐scale top‐to‐the‐N‐NNE Tertiary deformation that affected the whole Massif. Subsequent cooling occurred in the Middle Eocene (36 ± 2 Ma Ar‐Ar mica ages). Top‐to‐the‐N‐NNE structures were later overprinted by top‐to‐the‐S‐SSW fabrics within normal‐sense ductile shear zone, located between the core augen gneisses in the footwall and the structurally overlying cover schists in the hanging wall. The Massif was at the surface by the Early Miocene. Field relations clearly demonstrate that the age of top‐to‐the‐S‐SSW deformation is well constrained between the age of the MMM and the Early Miocene, and that exhumation was mainly tectonically controlled. Copyright © 2000 John Wiley &amp; Sons, Ltd.
Interventional MR Imaging for Injection of Sacroiliac Joints in Patients with Sacroiliitis
2000-07-01

Interventional MR Imaging for Injection of Sacroiliac Joints in Patients with SacroiliitisPhilippe L. Pereira1, Ilhan Günaydin2, Jochen Trübenbach1, Florian Dammann1, Christopher T. Remy1, Ina Kötter2, Fritz Schick1, Claudius W. Koenig1 and Claus D. Claussen1Audio Available | Share
Patterns of care for patients with primary differentiated carcinoma of the thyroid gland treated in Germany during 1996
2000-07-01

To the authors' knowledge no single effective diagnostic test for thyroid carcinoma currently is available and in the majority of cases a combination of ultrasound, thyroid scan, or fine-needle aspiration biopsy together with the clinical findings (e.g., thyroid mass) led to a diagnosis of carcinoma. The authors suspect that the high prevalence of concomitant pathologic findings such as goiter, even in the healthy population in Germany, reduces the accuracy of all diagnostic test methods and may account for the frequent use of imaging techniques. The majority of patients underwent a total or near-total thyroidectomy. Total thyroidectomy with radical lymph node dissection was used very frequently in those patients with papillary thyroid carcinoma (22%). German physicians tend to surgically treat early stage thyroid carcinoma somewhat more radically than recommended in the CPG. With respect to other treatment options employed as part of the first course of treatment, radioiodine appears to play the most important role. [See commentary o
Cloning, Overexpression, and Purification of Novobiocic Acid Synthetase from Streptomyces spheroides NCIMB 11891
2000-07-01

Novobiocic acid synthetase, a key enzyme in the biosynthesis of the antibiotic novobiocin, was cloned from the novobiocin producer Streptomyces spheroides NCIMB 11891. The enzyme is encoded by the gene novL, which codes for a protein of 527 amino acids with a calculated mass of 56,885 Da. The protein was overexpressed as a His(6) fusion protein in Escherichia coli and purified to apparent homogeneity by affinity chromatography and gel chromatography. The purified enzyme catalyzed the formation of an amide bond between 3-dimethylallyl-4-hydroxybenzoic acid (ring A of novobiocin) and 3-amino-4,7-dihydroxy-8-methyl coumarin (ring B of novobiocin) in an ATP-dependent reaction. NovL shows homology to the superfamily of adenylate-forming enzymes, and indeed the formation of an acyl adenylate from ring A and ATP was demonstrated by an ATP-PP(i) exchange assay. The purified enzyme exhibited both activation and transferase activity, i.e. it catalyzed both the activation of ring A as acyl adenylate and the subsequent transfer of the acyl group to the amino group of ring B. It is active as a monomer as determined by gel filtration chromatography. The reaction was specific for ATP as nucleotide triphosphate and dependent on the presence of Mg(2+) or Mn(2+). Apparent K(m) values for ring A and ring B were determined as 19 and 131 micrometer respectively. Of several analogues of ring A, only 3-geranyl-4-hydroxybenzoate and to a lesser extent 3-methyl-4-aminobenzoate were accepted as substrates.
Localization in Tissues and Secretion of Eotaxin by Cells from Normal Endometrium and Endometriosis1
2000-07-01

Our laboratories have focused recently on the production and localization of eotaxin, a C-C-chemokine of 8.4 kDa, whose major biological activity is the chemoattraction of eosinophils. Given evidence of autoimmune activity in the endometriosis syndrome, we hypothesized that eosinophil chemoattractants might be expressed in endometriosis. In histological sections, we observed eotaxin protein localized mainly in epithelial cells, with only very faint immunostaining in the surrounding stromal cells. Prominent eotaxin accumulation was noted in the luminal epithelium of secretory endometrium. Eotaxin distribution in endometriosis was similar to that seen in eutopic endometrium but with higher levels of eotaxin staining in the glandular epithelium. Peritoneal fluid concentrations of eotaxin were significantly higher in women with moderate or severe endometriosis than in women with minimal or mild endometriosis or no disease. The treatment of isolated human endometriosis epithelial cells with estradiol, medroxyprogesterone acetate, tumor necrosis factor-alpha, and interferon-gamma stimulated measurable eotaxin secretion into the conditioned media. The results indicate that eotaxin is produced in epithelial cells of normal endometrium and endometriosis tissues, varies across the menstrual cycle, and is elevated in women with endometriosis. We postulate that eotaxin, interacting with other known cytokines and immune cells, contributes to an inflammatory reproductive tract environment, leading to endometrial or blastocyst dysfunction.
The fate of global information in dorsal simultanagnosia
2000-07-01

Abstract We report a patient with simultanagnosia and Bálint-Holmes syndrome, following bilateral parieto-occlpital lesions, who exhibits a selective disturbance of global processing in everyday situations and in clinical tasks. For hierarchical Navon stimuli, where global letters are formed by the layout of smaller local letters, she could report only local shapes. She could identify the global form via proprioceptive input, when her finger was passively moved to trace the global shape, provided her eyes were closed. However, with her eyes open, the local visible form dominated once again even when the global shape was traced. This demonstrates dominance of pathological vision over intact proprioception, and shows that local capture persists even when the global information can still be processed by the patient, through another modality. This raises the possibility that some visual global processing might likewise still take place despite the local capture. In accordance wlth this notion, additional experiments showed that the patient was faster at naming local shapes if the global shape had the same identity rather than an incongruent identity. Moreover, a visual-search task found that parallel searching for unique features was preserved across the visual field. Taken together, our experiments suggest that the dominance of the local scale for KB is not due to a total inability to code any global information, but rather to an attentional bias towards salient local details following her brain damage.
Impact of subpatent multi-species and multi-clonal plasmodial infections on anaemia in children from Nigeria
2000-07-01

Childhood anaemia in sub-Saharan Africa is often caused by Plasmodium falciparum malaria. The influence of subpatent, multi-species and polyclonal infections with malaria parasites on haematological parameters was assessed in 1996/97 in clinically healthy children in Nigeria. Of the 228 children studied, 64% were anaemic by the WHO age-dependent criteria. A univariate analysis of risk factors indicated that the prevalence of anaemia was dependent on the number of Plasmodium species detected by species-specific PCR (P < 0.0001). Furthermore, the prevalence of anaemia increased gradually with the complexity (P < 0.003) as well as with the extent of P. falciparum parasitaemia (P < 0.0001). A logistic regression analysis revealed that individuals with an enlarged spleen tended to be anaemic. The number of Plasmodium species by which an individual was infected was independently associated with anaemia (P < 0.03). ANOVA revealed that the age-corrected values for haemoglobin (Hb) and red blood cells (RBCs) were mainly influenced by the occurrence of mixed infections. Haematological parameters were also influenced by the number of different P. falciparum clones by which an individual was infected. Hb levels and RBC counts were further diminished by additional infections with P. malariae and/or P. ovale. However, the effect of multi-species infections on haematological parameters exceeded that of multi-clonal infections.
Preparation of response force and movement direction: Onset effects on the lateralized readiness potential
2000-07-01

Two experiments assessed the preparatory effects of advance information about response force and movement direction on the lateralized readiness potential (LRP). In a choice reaction time (RT) task, an imperative stimulus required an isometric flexion or an extension of the left or right index finger. Prior information about response force or about movement direction reduced RT and shortened the interval from the onset of the imperative stimulus up to the onset of the LRP. Advance information, however, about direction but not about force decreased the interval from LRP onset to the onset of the overt response. The identical pattern of results was obtained in a second experiment, in which each participant performed both precue conditions. The findings of both experiments support the notion that response force is specified before movement direction. These results are consistent with the view accordingly different mechanisms are involved in the specification of muscle force and movement direction.
CD164 Monoclonal Antibodies That Block Hemopoietic Progenitor Cell Adhesion and Proliferation Interact with the First Mucin Domain of the CD164 Receptor
2000-07-01

Abstract The novel sialomucin, CD164, functions as both an adhesion receptor on human CD34+ cell subsets in bone marrow and as a potent negative regulator of CD34+ hemopoietic progenitor cell proliferation. These diverse effects are mediated by at least two functional epitopes defined by the mAbs, 103B2/9E10 and 105A5. We report here the precise epitope mapping of these mAbs together with that of two other CD164 mAbs, N6B6 and 67D2. Using newly defined CD164 splice variants and a set of soluble recombinant chimeric proteins encoded by exons 1–6 of the CD164 gene, we demonstrate that the 105A5 and 103B2/9E10 functional epitopes map to distinct glycosylated regions within the first mucin domain of CD164. The N6B6 and 67D2 mAbs, in contrast, recognize closely associated and complex epitopes that rely on the conformational integrity of the CD164 molecule and encompass the cysteine-rich regions encoded by exons 2 and 3. On the basis of their sensitivities to reducing agents and to sialidase, O-sialoglycoprotease, and N-glycanase treatments, we have characterized CD164 epitopes and grouped them into three classes by analogy with CD34 epitope classification. The class I 105A5 epitope is sialidase, O-glycosidase, and O-sialoglycoprotease sensitive; the class II 103B2/9E10 epitope is N-glycanase, O-glycosidase, and O-sialoglycoprotease sensitive; and the class III N6B6 and 67D2 epitopes are not removed by such enzyme treatments. Collectively, this study indicates that the previously observed differential expression of CD164 epitopes in adult tissues is linked with cell type specific post-translational modifications and suggests a role for epitope-associated carbohydrate structures in CD164 function.