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Elemental composition of platelets. Part I. Sampling and sample preparation of platelets for trace-element analysis.

Sampling of platelets for trace-element analysis poses special problems: obtaining adequate sample material, achieving a sufficient cell purity, preserving viability (integrity), correcting for trapped plasma, and controlling contamination. We used a blood-cell separator for the primary isolation of platelets from blood, and differential centrifugation in natural plasma to further isolate them. The pyrimidopyrimidine RA233 was used as a stabilizer to maintain viability. 131I-labeled human serum albumin was used to estimate trapped plasma. Contamination was controlled by using five-times-distilled water to simulate donor's blood in the system and by comparing three fractions: the serum, the first portion of the platelet-rich plasma, and the supernatant plasma after the final centrifugation. Neutron activation analysis was used for the elemental analysis. A single differential centrifugation of the platelet-rich plasma from the blood-cell separator at 400 x g for 8 min was optimum (mean mass fractions:erythrocytes/platelets less than 5 mg/g and leukocytes/platelets less than 20 mg/g). The trapped plasma in the wet platelet samples amounted to about 0.40 g/g. No appreciable contamination from the sampling system was found for the elements Ag, Cd, Co, Cr, Cs, Cu, Fe, Mo, Rb, Sb, Se, and Zn.

Blood Platelets↗

[Disorders in trace element status in cattle from the view of herd supervision. 1: Classical trace elements].

In a bipartite review the current knowledge about trace elements in cattle is described. The first part contains the classical trace elements iron, zinc, copper, manganese, molybdenum, iodine, selenium, cobalt, chromium and fluorine. For each trace element the following aspects are illustrated: physiological function, factors leading to deficiency or over-supply, symptoms of deficiency and poisoning and the diagnostic.

Animal Husbandry↗

Upstream elements involved in the embryonic regulation of the sea urchin CyIIIb actin gene: temporal and spatial specific interactions at a single cis-acting element.

The sea urchin Strongylocentrotus purpuratus CyIIIb actin gene codes for a cytoskeletal type actin and is activated in the early embryo specifically in the cells destined to become the aboral ectoderm. Deletion constructs of its upstream region fused to the bacterial chloramphenicol acetyltransferase (CAT) gene were expressed in developing embryos following microinjection into eggs. These studies revealed the segments of the upstream region which are necessary for embryonic expression. We mapped the protein:DNA interaction sites in this upstream region by DNase I footprinting. At least five binding sites were identified in the 2173 nucleotide flanking sequence, which seem to include all the necessary elements for quantitative expression. One of these elements (E1) showed different patterns of association in vitro with nuclear proteins isolated from different stages in development. These different interactions are separated when nuclear extracts from ectodermal or endodermal-mesodermal tissues were used. When S. purpuratus eggs were injected with a CAT fusion construct mutated at this site, a decrease in CAT activity was observed only in late stage embryos (plutei), whereas early stage embryos (blastulae) exhibited wild-type CAT activity. These results suggest that the E1 element is involved in the temporal regulation of the CyIIIb gene.

Actins↗

Dietary intakes of selected elements from longitudinal 6-day duplicate diets for pregnant and nonpregnant subjects and elemental concentrations of breast milk and infant formula.

As part of a longitudinal investigation into mobilization of lead from the maternal skeleton during pregnancy and lactation, we have determined the daily intake of selected elements (hereafter called micronutrients) for various subjects and compared these intakes with recommended and/or published intakes, especially those of the United States, through the U.S. National Health and Nutrition Examination Survey (NHANES). We also sought to ascertain whether there was any seasonal effect in the diets. Six-day duplicate diets were collected from 15 pregnant and 16 nonpregnant migrants to Australia, 6 pregnant Australian control subjects, and 8 children of nonpregnant migrants (6 to 11 years). Samples of breast milk and infant formula were also analyzed. Blended samples were analyzed by inductively coupled plasma mass spectrometry for the elements Ca, Cu, Fe, Mg, P, K, Na, Zn, Ba, Sr, and Pb. Daily intakes of micronutrients were only about half of the daily intake estimated for non-Hispanic white females and infants in the U.S. NHANES III. Estimates of daily intakes from breast milk were also considerably lower for the migrant and Australian infants compared with the values extracted from tables of food composition and dietary recall for non-Hispanic white infants in the U.S. NHANES III. For example, Ca was a factor of approximately 3 times lower, Fe approximately 50, and Zn approximately 4. We consider our estimates a reliable indication of the daily intakes for several reasons, including the collection of up to nine quarterly collections of 6-day duplicate diets and retention of subjects in a longitudinal prospective study. The low intakes of the essential elements such as Ca, Fe, and Zn in all these population groups are of potential concern from a public health viewpoint.

Adult↗

Requirement for cooperative interaction of interleukin-6 responsive element type 2 and glucocorticoid responsive element in the synergistic activation of mouse metallothionein-I gene by interleukin-6 and glucocorticoid.

Metallothionein (MT)-inducing activity of interleukin (IL)-6 depends on the presence of glucocorticoid in hepatic cells. The synergistic action of IL-6 and glucocorticoid was observed in the transcriptional activation of the mouse MT (mMT)-I gene. We found that a 281-bp promoter was sufficient for IL-6 and glucocorticoid stimulation. Our inspection of this region revealed the putative type 1 and 2 IL-6 responsive elements (REs). Functional analyses of these regions were performed using luciferase reporter constructs, and it was observed that the type 2 IL-6RE exerted the major response to the IL-6 signal. The transcriptional factor binding to type 1 IL-6RE, nuclear factor-IL-6, hardly contributed to the activation of the mMT-I promoter by IL-6 and glucocorticoid. A glucocorticoid responsive element (GRE) was also required for the synergistic activation by IL-6 and glucocorticoid. Interestingly, this synergism was not observed when the type 2 IL-6RE and the GRE were kept apart. Therefore, the synergistic activation of the mMT-I gene by IL-6 and glucocorticoid may require not only that signal transducers and activators 3 (Stat3) and the glucocorticoid receptor (GR) bind to their respective responsive elements, but also that Stat3 and the GR physically interact with one another.

Acute-Phase Proteins↗

Putative cholinergic elements in the photosensory pineal organ and retina of a teleost, Phoxinus phoxinus L. (Cyprinidae). Distribution of choline acetyltransferase immunoreactivity, acetylcholinesterase-positive elements and pinealofugally projecting neurons.

Putative cholinergic neurons in the photosensory pineal organ of a cyprinid teleost, the European minnow, were studied by use of choline acetyltransferase (ChAT) immunocytochemistry and acetylcholinesterase (AChE) histochemistry. Pinealofugally projecting neurons were visualized using retrograde HRP-filling through their cut axons. For comparison, the distribution of choline acetyltransferase immunoreactivity (ChAT-IR) and AChE-positive elements in the retina was investigated. While the distributional patterns of ChAT-IR and strongly AChE-positive perikarya in the retina are similar and may represent the same neuronal population, ChAT-IR and AChE-positive elements in the pineal organ appear to belong to separate populations. In the retina, small- to medium-sized perikarya in the inner nuclear layer, and small perikarya in the ganglion cell layer are ChAT-IR and AChE positive. The entire inner plexiform layer is AChE positive, while only sublaminae 1, 2 and 4 are ChAT-IR. No indication of cholinergic activity was observed in the optic axon layer. In the pineal organ, ChAT-IR is restricted to small perikarya situated rostrally and dorsally in the pineal end-vesicle. AChE-positive neurons are present throughout the pineal end-vesicle and the pineal stalk. The pineal tract (the pinealofugally projecting axons of intrapineal neurons) is strongly AChE positive, but displays no ChAT-IR. The distribution of pinealofugally projecting neurons, labeled with retrogradely transported HRP, is markedly dissimilar to that of the ChAT-IR elements. It is proposed that the photosensory pineal organ transmits photic information to the brain via a non-cholinergic pathway.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholinesterase↗

Simultaneous multi-element analysis of trace elements in soil samples by means of high-resolution inductively coupled plasma sector field mass spectrometry (SF-ICP-MS).

The potential of SF-ICP-MS for trace element analysis in complex environmental matrices such as soil solutions was investigated. Spectral interferences found in mass spectra of soil matrices are presented in detail. Furthermore, the influences of single components of the soil matrix on the signal intensity of selected elements were studied. Detection limits of different elements are presented with respect to the composition of the matrix. A fast and accurate method for quasi-simultaneous determination of Al, Si, P, V, Cr, Mn, Fe, Ni, Co, Cu, Zn, As, Se, Sr, Mo, Cd, Sn, Hg and Pb in aqueous soil extracts was established.

Journal Article↗

Identification of the human insulin negative regulatory element as a negative glucocorticoid response element.

Insulin gene transcription in adults is restricted to pancreatic beta cells. Studies with both transgenic mice and islet cell lines have demonstrated that beta cell specific expression is conferred by the 5' flanking region of the insulin gene. Transfection analysis has shown that cell specific expression involved an interaction between both positive and negative promoter cis elements. An upstream region (between -258 and -279) of the human insulin promoter served as a site of negative regulation. Transfection analysis in the pancreatic cell line HIT T-15 M 2.2.2 revealed that a DNA fragment containing this region causes a 45% reduction in promoter activity when linked to the native insulin promoter and a 72% reduction when linked to a heterologous tk promoter. Electrophoretic mobility shift analysis of this negative regulatory region (NRE) reveals a complex pattern of binding, wherein two major and several minor complexes are observed. Competition experiments demonstrated that formation of the fastest mobility complex is completely inhibited with excess cold glucocorticoid responsive element (GRE) consensus oligonucleotide. Purified glucocorticoid receptor binding domain (T7X556) demonstrated binding to the NRE oligonucleotide. Functional studies showed that dexamethasone treatment of HIT T-15 M 2.2.2 cells containing an NRE-tk CAT plasmid decreased CAT gene expression by 48%. Analysis of the NRE revealed 73% homology with the negative GRE consensus sequence. These data show that the human insulin NRE is a negative glucocorticoid response element.

Animals↗

Integrating iron and oxygen/antioxidant signals via a combinatorial array of DNA - (antioxidant response elements) and mRNA (iron responsive elements) sequences.

Fe (cellular iron), O (dioxygen, antioxidant inducers, hydrogen peroxide), and P (protein phosphorylation) signals combine to regulate DNA activity (transcription/mRNA synthesis) for antioxidant/Phase II response proteins (e.g., ferritin H, ferritin L, thioredoxin reductase I, NAD(P)H quinone oxido-reductase, heme oxygenase1 and beta-globin) and mRNA activity for proteins of iron transport, storage or oxygen metabolism (e.g., ferritin H, ferritin L, transferrin receptor1, ferroportin, mt-aconitase-TCA cycle and aminolevulinate synthase - heme biosynthesis). Ferritin regulation links the two groups of genetic controls via DNA (ARE-antioxidant response element) and mRNA (IRE-iron responsive element) structures. More is known about the IRE-mRNA and protein repressors, IRPs (iron regulatory proteins/aconitase homologues), than the DNA-ARE and protein repressors, e.g., Bach1. Iron responsive elements are very similar (65-80% sequence identity), but each mRNA has sufficient IRE specificity (>90% phylogenetic sequence conservation), that IRP binding and signal responses vary quantitatively. The structural specificity of each IRE-RNA provides an opportunity for finding small molecule regulators in vitro, and possibly in vivo. The potential of manipulating mRNA function with small molecules targeted to specific RNA regulatory structures, e.g., ferritin mRNA in iron overload, or viral mRNA control structures for replication, is high.

Antioxidants↗

Structural basis of the interaction between P-element somatic inhibitor and U1-70k essential for the alternative splicing of P-element transposase.

P-element transposition in Drosophila is regulated by tissue-specific alternative splicing of the P-element transposase pre-mRNA. In somatic cells, the P-element somatic inhibitor (PSI) protein binds to exon 3 of the pre-mRNA and recruits U1 small nuclear ribonucleoprotein (snRNP) to the F1 pseudo-splice site. This abrogates binding of U1 snRNP to the genuine 5' splice site, thereby preventing excision of the third intron. Two homologous short sequences, referred to as the A and B boxes, near the C terminus of PSI bind to U1-70k protein within U1 snRNP. We have now mapped the AB box-binding site of U1-70k to a short proline-rich sequence at the C terminus. Our NMR study shows that the B box forms an anti-parallel helical hairpin in which four highly conserved aromatic residues form a cluster on one face of the first helix. This hydrophobic cluster interacts extensively with the proline-rich region of the U1-70k protein.

Alternative Splicing↗

Distribution of platinum group elements and other traffic related elements among different plants along some highways in Germany.

Using ICP-MS and ICP-AES platinum group elements (Pt, Pd, Rh, Ru and Ir) and Ce, La, Nd, Pb and Zr have been determined in street dust, Taraxacum officinale (dandelion), Plantago lanceolata (plantain), Lolium multiflorum (annual ryegrass), Rhytidiadelphus squarrosus (moss) and Vascellum pratense (mushrooms) collected along highways and streets in Germany during 1999. Among the plants Taraxacum officinale (dandelion) reflects most adequately the pollution with the investigated elements matching the results from street dust. A strong positive correlation between all elements determined in the plants is established. Transfer factor for Pt between soil and plants has been determined in an agricultural experiment ranging between 0.004 and 0.008 for two types of soils.

Agaricales↗

A CD30 responsive element in the germline epsilon promoter that is distinct from and inhibitory to the CD40 response element.

Germline epsilon (I epsilon) transcription is requisite for IgE switch recombination. I epsilon transcription is markedly increased by ligation of CD40 and/or by IL-4 stimulation. By contrast, we found previously that stimulation through CD30 inhibits I epsilon transcription in EBV-transformed B cell lines. To characterize the molecular mechanisms involved in these contradictory events, the promoter elements that are responsible for I epsilon transcriptional regulation were determined using stable CAT reporter gene constructs. The results define a 95 bp CD30 responsive element (CD30RE) located 5' of the previously defined CD40 responsive element (CD40RE) that resides within the same 95 bp fragment as the IL-4RE and ablates CD40L induced I epsilon promoter activity. However, IL-4 overrides the inhibitory effect of CD30L. These results define a CD30RE and provide further evidence for the complex regulation of I epsilon transcription by various members of the CD40L/TNF alpha family of molecules.

Base Sequence↗

Cell-type specific factors bind to regulatory elements located downstream of the TATA-box element in the mouse myelin basic protein (MBP) gene promoter.

Cell-type specific transcription of the myelin basic protein (MBP) gene in primary oligodendrocytes (OL) is regulated by cis-acting regulatory elements located at both upstream and downstream of the TATA-box region of the MBP promoter. To identify cell-type specific factors that bind to the downstream regulatory elements, we utilised DNase I footprinting analysis and gel retardation assays with nuclear extracts from myelin-forming OL as well as a non-myelin forming cell line, C6 glioma (C6) cells. Several regions of DNA were protected from DNAse I digestion by nuclear extracts of both cell types. However, two regions, from -17 to +17 and from +47 to +58 were protected specifically in OL, while three regions, from + 17 to + 22, from +43 to +49 and from +58 to +64 were protected only with C6 nuclear extracts. Inspection of the protected regions for homology with known transcription factor binding sites revealed that sequences at from +47 to +58 and from +56 to +68 showed extensive homology to the negative regulatory element (NRE1), of the mouse renin gene and to the interferon (IFN) consensus sequence of major histocompatibility complex class I genes (MHC I-ICS), respectively. Gel retardation assays using a MHC I-ICS oligonucleotide and transient transfection assays using MBP-CAT constructs were used to study the effect of IFNs on MBP promoter activity in OL and C6 cells. In OL, IFN-alpha/beta caused little induction of CAT activity, but IFN-gamma resulted in a 2-3.5-fold decrease in CAT activity. In contrast, in C6 cells both IFN-alpha/beta and IFN-gamma induced a 1.5-2.5-fold increase in CAT activity. The cooperative effects of factors binding to NREs and ICS may be responsible for the cell-type specific regulation of MBP gene transcription.

Animals↗

The Biological System of the Elements (BSE)--a brief introduction into historical and applied aspects with special reference on "ecotoxicological identity cards" for different element species (e.g. As and Sn).

There are different methods to estimate and predict effects of chemical elements and corresponding speciation forms in biochemistry and toxicology, including statements on essentiality and antagonisms. Two approaches are given here: (1) "identity cards" describing biologically fundamental aspects of element chemistry and (2) qualitative discussions which assume the existence of (indirect ways into) chemical autocatalysis to be essential for maintaining life and permitting reproduction. The latter method, developed by the present authors, draws upon Stoichiometric Network Analysis, a safe procedure for complexity reduction in feedback networks) and provides estimates of concentration regimes for different elements suitable for survival and reproduction. The biochemical hierarchy level considered here is that of (metallo-)proteins. Thermodynamic toxicity aspects are given in correlations with DMSO solvent affinities and thiocyanate bonding modes. Effects of antagonists and of ion substitution within metalloenzymes or of metabolic simplification can be dealt with, likewise increased sensitivities within symbiotic relationships and within carcinomas are explained which are relevant for environmental monitoring and tumour therapy, respectively.

Animals↗

Elemental speciation by parallel elemental and molecular mass spectrometry and peak profile matching.

Trace elemental speciation in complex, real-world matrixes is a daunting task because of the low concentration of metals/metalloids and the correspondingly high molecular chemical noise. We constructed a liquid chromatography parallel elemental and molecular mass spectrometry (PEMMS) system and evaluated the use of peak elution profiles to identify trace molecular species containing specific heteroatoms, using the case of Se in yeast. We demonstrate that it is possible to use the HPLC-inductively coupled plasma (ICP)MS peak profile (retention time, width) to identify candidate ions with matching peak profiles in the molecular MS data. Proof of principle was demonstrated by C18 separation of three Se-amino acid standards (0.005-15 ppm as Se). The molecular MS (atmospheric pressure chemical ionization time-of-flight, APCI-TOF-MS) data set was converted into selected ion chromatograms of 0.05 Th width. ICPMS and APCI-TOF-MS ion chromatograms were fit by the Haarhoff-VanderLinde function using the following parameters: area, retention time, width, and skew. The ICPMS fit parameters were more reproducible than the APCI-TOF-MS fit parameters from run to run, and the APCI-TOF-MS signal was expected to limit correlation in most circumstances. Retention time and width were found to correlate well between the two MS systems for APCI-TOF-MS peaks with signal-to-fit-error (S/FE) of >25. Correction factors for differences in flow path length and peak broadening were required. The normalized correction factors were species and concentration independent and were stable from run to run. The skew parameter was found to be highly susceptible to noise and was not generally useful in matching ICPMS and APCI-TOF-MS peaks. An artificially noisy sample was generated by spiking 30 ppb Se-methionine (SeMet) and 5 ppb Se-methylselenocysteine (SeMSC) with unselenized yeast extract and run by PEMMS. The PEMMS software was able to detect four molecular MS peaks associated with SeMet and two for SeMSC, while filtering out >40 coeluting spectral peaks associated with chemical noise in each sample. In summary, we have demonstrated that correlated information in peak shape between parallel detectors can facilitate detection of trace elemental species in complex matrixes.

Journal Article↗

Characterization of the mouse metal-regulatory-element-binding proteins, metal element protein-1 and metal regulatory transcription factor-1.

Metal activation of metallothionein gene transcription depends mainly on the presence of regulatory DNA sequences termed metal-regulatory elements (MREs) and involves MRE-binding transcription factor-1 (MTF-1) interacting with the MREs in a Zn(2+)-dependent manner. We previously identified and characterized a nuclear protein, termed metal element protein-1 (MEP-1), specifically binding with high affinity to MRE elements. The precise relationship between MTF-1 and MEP-1 was unclear, and to determine whether MEP-1 and MTF-1 were distinct protein species, we performed DNA binding analyses to characterize the binding properties of both proteins. Electrophoretic mobility-shift assays showed that MTF-1, produced in COS cells, produces a slower-migrating band compared with that obtained with purified MEP-1. Using an anti-MTF-1 antibody, we showed that both the MTF-1-MRE and the MEP-1-MRE complexes are supershifted by an anti-MTF-1 antibody, thus demonstrating that MEP-1 is antigenically related to MTF-1. RNase protection analyses carried out with RNA prepared from different tissues and cell lines failed to reveal the presence of MTF-1 splicing variants. This indicates that MEP-1 may be a proteolytic fragment of MTF-1. MTF-1 DNA-binding activity was rapidly activated in vivo by Zn(2+) ions but not by Cd(2+), UV irradiation or PMA, and occurred on ice as well as at 21 degrees C. In control and Zn(2+)-treated cell extracts, DNA-binding activity was not enhanced in vitro following the addition of exogenous Zn(2+) or a preincubation at 37 degrees C. However, recombinant MTF-1 produced in vitro required Zn(2+) activation for DNA binding. Interestingly, treatment of nuclear extracts with calf intestine phosphatase completely abrogated MTF-1 DNA-binding activity, thus suggesting that phosphorylation is involved in the regulation of MTF-1 activity.

Animals↗

Structural and functional dissection of a conserved destabilizing element of cyclo-oxygenase-2 mRNA: evidence against the involvement of AUF-1 [AU-rich element/poly(U)-binding/degradation factor-1], AUF-2, tristetraprolin, HuR (Hu antigen R) or FBP1 (far-upstream-sequence-element-binding protein 1).

COX-2 (cyclo-oxygenase-2) mRNA is degraded rapidly in resting cells, but is stabilized by the mitogen-activated protein kinase p38 signalling pathway in response to pro-inflammatory stimuli. A conserved ARE (AU-rich element) of the COX-2 3' untranslated region, CR1 (conserved region 1), acts as a potent instability determinant, and mediates stabilization in response to p38 activation. A detailed structural and functional analysis of this element was performed in an attempt to identify RNA-binding proteins involved in the regulation of COX-2 mRNA stability. Destabilization of a beta-globin reporter mRNA was dependent upon two distinct AREs within CR1, each containing three copies of the sequence AUUUA. CR1 was shown to bind AUF-1 [ARE/poly(U)-binding/degradation factor-1] and/or AUF-2, HuR (Hu antigen R), TTP (tristetraprolin) and FBP1 (far-upstream-sequence-element-binding protein 1), yet these factors did not appear to account for the effects of CR1 upon mRNA stability. Mutant sequences were identified that were incapable of destabilizing a reporter mRNA, yet showed unimpaired binding of FBP1 and AUF-1 and/or -2. TTP was absent from the HeLa cell line used in this analysis. Finally, RNA interference experiments argued against a prominent role for HuR in the CR1-mediated regulation of mRNA stability. We conclude that at least one critical regulator of COX-2 mRNA stability is likely to remain unidentified at present.

3' Untranslated Regions↗

Role of interferon-stimulated responsive element-like element in interleukin-8 promoter in Helicobacter pylori infection.

BACKGROUND & AIMS: Gastric mucosal interleukin (IL)-8 levels are related to the presence of both the cag pathogenicity island (PAI) and OipA. We investigated the regions of the IL-8 promoter and the upstream signaling involved in IL-8 gene transcription. METHODS: We cocultured parental Helicobacter pylori and isogenic oipA, hopZ, or cagE gene knockout mutants with gastric cancer cells. The regulatory sites in the IL-8 promoter were examined by luciferase reporter gene assay, electrophoretic mobility shift assays, and immunoblot analyses. Phosphorylated signal transducers and activators of transcription 1 (STAT1) levels in the antral gastric mucosa were measured by enzyme-linked immunosorbent assay. RESULTS: Maximal H. pylori -induced IL-8 gene transcription required the presence of the interferon-stimulated responsive element (ISRE)-like element, nuclear factor (NF)-kappa B and activator protein (AP)-1 binding sites. In vitro studies showed that OipA and the cag PAI were involved in inducing interferon regulatory factor (IRF)-1 to bind and activate the ISRE-like element and that the cag PAI, but not OipA, was involved in activating AP-1 and NF-kappa B. Both in vitro and in vivo studies showed that OipA, but not the cag PAI, was involved in STAT1 phosphorylation, as upstream signaling of IRF-1. CONCLUSIONS: OipA and the cag PAI are both necessary for full activation of the IL-8 promoter but act via different pathways that diverge upstream of IRF-1 where only OipA is involved in the STAT1-IRF1-ISRE pathway. The mucosal inflammatory response to H. pylori infection is complex and involves different pathways converging on the IL-8 promoter.

Antigens, Bacterial↗