bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cadmium and human health: A perspective based on recent studies in China
Authors: Nordberg Gunnar 
Published: October 2003

AbstractCadmium (Cd) occurs in low concentrations in all human diets and in cigarettes. In contaminated areas and in certain occupations, high human exposures occur. In assessing risk to human health, it is important to identify the adverse effect that occurs at the lowest exposure level, i.e., the critical effect, which is crucial for preventive action. Excessive Cd exposure may give rise to renal, pulmonary, hepatic, skeletal, reproductive effects, and cancer. Previous evaluations (e.g., by WHO) have identified renal dysfunction, occurring in long‐term Cd exposure, as the critical effect. However, skeletal and reproductive effects are also discussed as possible critical effects. For preventive action, information is important about exposure levels that give rise to the earliest (critical) effects. To gain new information on this issue, population groups in China exposed to high concentrations of Cd via rice and Cd‐exposed workers were studied for possible renal, skeletal, and male reproductive toxicity. Skeletal effects in terms of decreased bone mineral density and an increased occurrence of fractures were found in groups of the general population living in the most Cd‐exposed area. Our studies further show that renal effects measured by sensitive biomarkers, such as urinary content of beta‐2‐microglobulin, calcium, and N‐acetyl‐beta‐D‐glucosaminidase, occurs at lower cumulative exposures to Cd than those giving rise to skeletal effects and also at lower exposures than previously estimated, e.g., by WHO. The findings confirm the renal dysfunction as the critical effect of long‐term Cd exposure. Metallothionein (MT) gene expression in peripheral blood lymphocytes was measured in Cd exposed workers. A higher prevalence of renal dysfunction was found among Cd exposed workers with low MT gene expression than among those with high MT gene expression, at similar blood and urinary Cd levels. MT gene expression in PBLC thus may be a biomarker for identifying sensitive population groups. J. Trace Elem. Exp. Med. 16:307–319, 2003. © 2003 Wiley‐Liss, Inc.
Regulation of tyrosine phosphorylation cascades by phosphatases: What the actions of vanadium teach us
Authors: Hulley Philippa , Davison Allan 
Published: October 2003

AbstractProtein phosphorylation and dephosphorylation regulate much of the machinery of the cell. Emphasis in recent years has swung toward regulation by dephosphorylation. Much current research focuses on protein tyrosine phosphatases. Researchers of cellular regulation use vanadium as a probe because of its unparalleled ability to selectively inhibit protein tyrosine phosphatases at submicromolar concentrations. This review focuses on the biological actions of vanadium relevant to cellular regulatory cascades. Recent research has led to identification of control points and possible drug targets in 1) the glucose control mechanisms downstream from insulin receptors; 2) pathways regulating mitogenesis, tumor promotion, and other events downstream from growth factor receptors; 3) regulation of osteogenesis and possibilities for counteracting the bone damaging actions of glucocorticoids. An up‐to‐date understanding of the mechanisms by which vanadium acts and of its currently identified targets is prerequisite to the intelligent design of experiments of this kind. In this review, we will consider mechanisms at the enzymological level, in cellular regulatory cascades, and events affecting the cell or organism as a whole. J. Trace Elem. Exp. Med. 16:281–290, 2003. © 2003 Wiley‐Liss, Inc.
Dietary boron: An overview of the evidence for its role in immune function
Authors: Hunt Curtiss D. 
Published: October 2003

AbstractThis review summarizes the evidence for boron essentiality across the biological spectrum with special focus on biochemical pathways and biomolecules relevant to immune function. Boron is an essential trace element for at least some organisms in each of the phylogenetic kingdoms Eubacteria, Stramenopila (brown algae and diatoms), Viridiplantae (green algae and familiar green plants), Fungi, and Animalia. Discovery of several of the currently recognized boron‐containing biomolecules was achieved because the bound boron formed four coordinate covalent bonds with the ligand, creating a thermodynamically stable complex that is almost undissociable in water. Boron is a constitutive element in three antibiotics and a quorum‐sensing signal in bacteria. It enhances Fc receptor expression and interleukin‐6 production in cultured mammalian macrophages. Boron binds tightly to the diadenosine polyphosphates and inhibits the in vitro activities of various serine protease and oxidoreductase enzymes. Physiological amounts of dietary boron decrease skinfold thickness after antigen injection in gilts and elevated circulating natural killer cells after adjuvant injection in rats. It is predicted that several boron biomolecules waiting discovery are signaling molecules that interact with the cell surface and are probably composed of two mirror or near‐mirror halves stabilized by a single boron atom to form a large circular biomolecule. J. Trace Elem. Exp. Med. 16:291–306, 2003. Published 2003 Wiley‐Liss, Inc.
Zinc is essential for brain development and function
Authors: Sandstead Harold H. 
Published: October 2003

AbstractZinc's roles in brain function are poorly understood. Zinc is essential pre‐ and postnatally for growth, maturation, and function. In early pregnancy, zinc is essential for cell multiplication and implantation of the embryo and for cell differentiation and organ formation. Deficiency causes teratology in all tissues. Zn deficiency in later pregnancy impairs neuronal replication and migration (as observed in cerebellar external granular cells). Synaptogenesis is impaired (as observed in Purkinje cells). It has been proposed that zinc deficiency impairs calcium channels causing a decrease in intracellular calcium that suppresses gene expression of growth factors and synthesis of nucleic acids and proteins. Whatever the mechanism, effects in experimental animals include poorly reversible impairments in learning and memory later in life, which appears associated with decreased neuronal survival. It is unknown if similar phenomena occur in humans. It is known however that low fetal growth, a process caused by maternal zinc deficiency, is risk factor for coronary heart disease, type 2 diabetes mellitus, chronic lung disease, and obesity. One wonders if fetal growth is related to later neuronal health and function. J. Trace Elem. Exp. Med. 16:165–173, 2003. © 2003 Wiley‐Liss, Inc.
Gastrointestinal nematodes, trace elements, and immunity
Authors: Koski Kristine G. , Scott Marilyn E. 
Published: October 2003

AbstractThe exploration of the scientific literature on the interrelationship among trace elements, gastrointestinal nematodes, and their requisite Th2 immunity demonstrates extensive literature but regrettably, research remains inadequate and sparse, with far fewer studies having investigated the interrelationship among trace elements and host immunity in infected hosts. Gastrointestinal nematodes, such as hookworms, Ascaris lumbricoides, and Trichuris trichiura, require activation of the Th2 arm of the immune cascade and the expression of the Th2 cytokines (interleukin‐4, interleukin‐5, and interleukin‐10) and their effectors for worm expulsion. However, parasites have evolved a series of strategies to invade the host and to evade host defense mechanisms. Many of these mechanisms involve metalloproteinases for tissue invasion and enzymes, such as catalase and superoxide dismutase, to minimize free radical damage to the parasitic tissues from the host's immune system. Deficiencies of iron, molybdenum, copper, and zinc, have been associated with higher worm burdens, as have excessive intakes of molybdenum, iron, and copper. The possibility is emerging that there may be an optimum trace element level in the diet above which and below which the parasite is advantaged. Moreover, there is some data to suggest that specific trace elements may be directly toxic to the parasite. J. Trace Elem. Exp. Med. 16: 237–251, 2003. © 2003 Wiley‐Liss, Inc.
Arsenic essentiality: A role affecting methionine metabolism
Authors: Uthus Eric O. 
Published: October 2003

AbstractAlthough there is no known biological function of arsenic, considerable evidence suggests that arsenic has a physiological role related to methionine metabolism. In early studies using amino acid‐based diets, it was found that arsenic deprivation had little effect on growth in rats fed adequate methionine. However, in rats fed suboptimal methionine, arsenic deprivation resulted in a significant reduction in body weight. Other studies showed that feeding methyl depletors caused severe signs of arsenic deprivation. Because it was found that alteration in methionine status or methyl metabolism affected signs of arsenic deprivation, and that many of these signs were related to methionine or methyl metabolism, it was hypothesized that arsenic has a physiological role affecting methionine metabolism. In animal studies testing this hypothesis, it was shown that arsenic deprivation reduces the hepatic concentration of S‐adenosylmethionine. Additionally, arsenic status affects DNA methylation in animal and cell culture models; very low or high doses of arsenic, compared with control amounts, result in an apparent hypomethylation of DNA. Because global DNA hypomethylation is associated with an increased incidence of cancer, we tested whether dietary arsenic (deficient, adequate, or excess; 0, 0.5 or 50 μg arsenic/g diet, respectively) would affect the formation of aberrant crypts in rats treated with the carcinogen dimethylhydrazine. Aberrant crypts are preneoplastic lesions that have been associated with colon carcinomas. More aberrant crypts were observed in rats fed the high amount of dietary arsenic compared to those fed adequate arsenic. The number of aberrant crypts in the arsenic‐deprived group also tended to be higher than those found in rats fed adequate arsenic. Thus, many findings indicate that arsenic plays a role in methionine/methyl metabolism; however, the site of action of arsenic remains unknown. Possibly, arsenic is instrumental in maintaining the metabolic pool of S‐adenosylmethionine. These results show that compared to controlled amounts, having too little or too much arsenic in the diet is harmful. That is, there is an amount of dietary arsenic that is not only not harmful, but beneficial. J. Trace Elem. Exp. Med. 16:345–355, 2003. Published 2003 Wiley‐Liss, Inc.
Copper‐lowering therapy with tetrathiomolybdate for cancer and diseases of fibrosis and inflammation
Authors: Brewer George J. 
Published: October 2003

AbstractAngiogenesis is required for tumor growth and is a likely Achilles heel for cancer. However, antiangiogenic agents have been somewhat disappointing in cancer therapy, perhaps because they target a single angiogenic factor, and there is much redundancy in angiogenic systems. Copper is required for high levels of angiogenesis, and many angiogenic factors have a requirement for copper. Thus, anticopper drugs offer the possibility of more global inhibition. Our group has developed tetrathiomolybdate (TM) for the initial treatment of neurologic Wilson's disease. Penicillamine makes about 50% of these patients neurologically worse, and many never recover. Only 2 of 55 (3.6%) patients worsened when treated with TM. Because TM exhibited desirable properties of potency, speed, and safety, we studied it as an antiangiogenic agent. We hypothesize that if copper is lowered to midrange, the cellular requirements for copper are met, but angiogenic cytokine signaling is inhibited. TM has shown strong inhibition of cancer growth in five rodent models, encouraging results in a canine study of advanced and metastatic cancer, and encouraging results in a phase 1/2 study of advanced and metastatic cancer in 42 patients. Finally, we have hypothesized that the pathway of fibrosis involving transforming growth factor beta (TGF‐β) and connective tissue growth factor is inhibitable by copper‐lowering therapy with TM. This pathway is overactive and dysregulated in many diseases of fibrosis. In animal studies, TM has completely inhibited the pulmonary fibrosis induced by bleomycin, the hepatitis induced by concanavalin A, and the cirrhosis induced by carbon tetrachloride. We find that TM inhibits transforming growth factor beta and inflammatory cytokines tumor necrosis factor alpha and interleukin‐1‐beta. J. Trace Elem. Exp. Med. 16:191–199, 2003. © 2003 Wiley‐Liss, Inc.
Zinc status (plasma and hair zinc concentrations) during pregnancy: A longitudinal study
Authors: Çavdar A.O. , Söylemez F. , Cengiz B. , Aydemir F. 
Published: October 2003

AbstractA longitudinal study of plasma and hair zinc concentration analysis was performed in 51 and 38 pregnant women, respectively. Plasma zinc levels were followed from first trimester to the end of second trimester, whereas hair zinc concentrations were measured in all trimesters. They were all measured by atomic absorption spectrophotometer. Both plasma and hair zinc levels declined significantly during the second trimesters There was also a significant difference in plasma zinc levels between the “well‐nourished” and “poorly nourished” groups (P < 0.001 and P < 0.05)Similar changes could not be observed for hair zinc concentrations, probably because of the fact that all pregnant women were from Ankara rather than from villages, where the dietary habit is frequently associated with zinc deficiency. J. Trace Elem. Exp. Med. 16:175–179, 2003. © 2003 Wiley‐Liss, Inc.
An overview of the role of iron in T cell activation
Authors: Kuvibidila Solo , Warrier Raj P. , Surendra Baliga B. 
Published: October 2003

AbstractIron, an essential growth trace element, is required for proliferation of all living cells, including T lymphocytes. Many, though not all, immune responses require lymphocyte proliferation. Iron deficiency, a worldwide public health problem for children and for women of childbearing age, is associated with impaired lymphocyte proliferative responses to mitogens and cell‐mediated immunity. However, the mechanisms have not been fully elucidated. Our data on certain early key events in the T cell activation pathways, obtained from iron‐deficient murine splenic T lymphocytes, show reductions in hydrolysis of cell membrane phosphatidyl inositol 4,5 bisphosphate, protein kinase C activation, and interleukin‐2 secretion. Although the expression of CD3 molecule (a component of the T cell‐receptor/CD3 complex, required for T cell activation) is not decreased by iron deficiency in splenocytes and thymocytes, the expression of the co‐stimulatory molecule, CD28, is. Iron‐deficiency increases the percentage of CD3+/CD28− thymocytes but decreases that of CD3−/CD28+ cells. Iron deficiency and iron chelation by deferoxamine decrease CD28 fluorescence intensity but tends to increase that of CD3. Progression of activated spleen cells through the cell cycle (Go/G1, S, G2/M phases) is also altered by iron deficiency independently of differences in the percentages of CD3+ T cells between groups, probably through impaired transition of G1 to S phase. Data suggest that the role of iron in T cell proliferation is not limited to the regulation of ribonucleotide reductase activity, but also involves other steps in the T cell activation pathways. J. Trace Elem. Exp. Med. 16:219–225, 2003. © 2003 Wiley‐Liss, Inc.
Zinc and immunity: Molecular mechanisms of zinc action on T helper cells
Authors: Prasad Ananda S. 
Published: October 2003

AbstractThe essentiality of zinc for humans was recognized in 1963. It is now evident that nutritional deficiency of zinc in human populations throughout the developing world is common. The major factor responsible for this deficiency is the consumption of mainly cereal proteins rich in phytate. The clinical manifestations of zinc deficiency include growth retardation and male hypogonadism in the adolescents, rough skin, poor appetite, mental lethargy, delayed wound healing, cell‐mediated immune dysfunctions, and abnormal neurosensory disorders. A conditioned deficiency of zinc has been observed in many diseased states. In this work I have summarized our current knowledge concerning the molecular mechanisms of zinc action on T helper cells. Our studies showed that in zinc‐deficient HUT‐78 cells, phosphorylated IκB and Iκk, ubiquitinated IκB, and binding of nuclear factor (NF)‐κB to DNA were significantly decreased. Zinc increased the translocation of NF‐κB from cytosol to nucleus. These data show that zinc plays an important role in the activation of NF‐κB in HUT‐78 cells. We showed a significant effect of zinc on gene expression of interleukin (IL)‐2 and IL‐2 receptors α and β. We also showed that a decrease in gene expression of IL‐2 and its receptors in zinc‐deficient HUT‐78 cells may be the result of decreased activation of NF‐κB in zinc‐deficient cells. J. Trace Elem. Exp. Med. 16:139–163, 2003. © 2003 Wiley‐Liss, Inc.
On non‐normal del Pezzo surfaces
Authors: Abe Makoto , Furushima Mikio 
Published: October 2003

AbstractLetYbe a non‐normal del Pezzo surface over ℂ and letd≔ (ω−1Y)2> 0 be the degree ofY. Then we prove thatω⊗d−4Yis very ample ford= 1, 2.
Intrinsic characterizations of Besov spaces on Lipschitz domains
Authors: Dispa Sophie 
Published: October 2003

AbstractThe aim of this paper is to study the equivalence between quasi‐norms of Besov spaces on domains. We suppose that the domain Ω ⊂ ℝn is a bounded Lipschitz open subset in ℝn. First, we define Besov spaces on Ω as the restrictions of the corresponding Besov spaces on ℝn. Then, with the help of equivalent and intrinsic characterizations (the Peetre‐type characterization 3.10 and the characterization via local means 3.13) of these spaces, we get another equivalent and intrinsic quasi‐norm using, this time, generalized differences and moduli of smoothness. We extend the well‐known characterization of Besov spaces on ℝn described in Theorem 2.4 to the case of Lipschitz domains.
Analytical properties of measure geometric Krein‐Feller‐operators on the real line
Authors: Freiberg Uta 
Published: October 2003

AbstractWe investigate analytical properties of a measure geometric Laplacian which is given as the second derivative $ {d \over {d \mu}} {d \over {d \nu}} $ w.r.t. two atomless finite Borel measures μ and ν with compact supports supp μ ⊂ supp ν on the real line. This class of operators includes a generalization of the well‐known Sturm‐Liouville operator $ {d \over {d \mu}} {d \over {dx}} $ as well as of the measure geometric Laplacian given by $ {d \over {d \mu}} {d \over {d \mu}} $. We obtain for this differential operator under both Dirichlet and Neumann boundary conditions similar properties as known in the classical Lebesgue case for the euclidean Laplacian like Gauß‐Green‐formula, inversion formula, compactness of the resolvent and its kernel representation w.r.t. the corresponding Green function. Finally we prove nuclearity of the resolvent and give two representations of its trace.
On the index of a vector field tangent to a hypersurface with non‐isolated zero in the embedding space
Authors: Klehn Oliver 
Published: October 2003

AbstractWe give a generalization of an algebraic formula of Gomez‐Mont for the index of a vector field with isolated zero in (ℂn, 0) and tangent to an isolated hypersurface singularity. We only assume that the vector field has an isolated zero on the singularity here.
Blow up and global existence in a nonlinear viscoelastic wave equation
Authors: Messaoudi Salim A. 
Published: October 2003

AbstractIn this paper the nonlinear viscoelastic wave equation

associated with initial and Dirichlet boundary conditions is considered. Under suitable conditions on g, it is proved that any weak solution with negative initial energy blows up in finite time if p > m. Also the case of a stronger damping is considered and it is showed that solutions exist globally for any initial data, in the appropriate space, provided that m ≥ p.
Intersection theory for loaded cycles IV — resonant cases
Authors: Mimachi Katsuhisa , Ochiai Hiroyuki , Yoshida Masaaki 
Published: October 2003

AbstractWe study the structure of the twisted homology groups attached to weighted lines in the plane with resonant singular points, and find possible intersection pairings. As a typical example, we treat homology groups attached to 2‐dimensional Selberg‐type integrals.
On the spectral norm of algebraic numbers
Authors: Popescu Angel , Popescu Nicolae , Zaharescu Alexandru 
Published: October 2003

AbstractIn this paper we continue to study the spectral norms and their completions ([4]) in the case of the algebraic closure \documentclass{article} \usepackage{amssymb} \pagestyle{empty} \begin{document} $ \overline {\mathbb Q} $ \end{document} of ℚ in ℂ. Let \documentclass{article} \usepackage{amssymb} \pagestyle{empty} \begin{document} $ \widetilde{\overline{\mathbb{Q}}} $ \end{document} be the completion of \documentclass{article} \usepackage{amssymb} \pagestyle{empty} \begin{document} $ \overline {\mathbb Q} $ \end{document} relative to the spectral norm. We prove that \documentclass{article} \usepackage{amssymb} \pagestyle{empty} \begin{document} $ \widetilde{\overline{\mathbb{Q}}} $ \end{document} can be identified with the R‐subalgebra of all symmetric functions of C(G), where C(G) denotes the ℂ‐Banach algebra of all continuous functions defined on the absolute Galois group G = Gal\documentclass{article} \usepackage{amssymb} \pagestyle{empty} \begin{document} $ {\overline {\mathbb Q}} / {\mathbb Q} $ \end{document}. We prove that any compact, closed to conjugation subset of ℂ is the pseudo‐orbit of a suitable element of \documentclass{article} \usepackage{amssymb} \pagestyle{empty} \begin{document} $ \widetilde{\overline{\mathbb{Q}}} $ \end{document}. We also prove that the topological closure of any algebraic number field in \documentclass{article} \usepackage{amssymb} \pagestyle{empty} \begin{document} $ \widetilde{\overline{\mathbb{Q}}} $ \end{document} is of the form \documentclass{article} \usepackage{amssymb} \pagestyle{empty} \begin{document} $\widetilde{\mathbb{Q}[x]}$ \end{document} with x in \documentclass{article} \usepackage{amssymb} \pagestyle{empty} \begin{document} $ \widetilde{\overline{\mathbb{Q}}} $ \end{document}.
On the braid index of θm‐curve in 3‐space
Authors: Shinnoki Tomoko , Takamuki Takashi 
Published: October 2003

AbstractIn this paper we consider the braid index and the number of Seifert circles of a θm‐curve in ℝ3 as a generalization of the concepts on an oriented link and establish a relation between them and the degree of Yokota's polynomial invariant.
An algorithm for the divisors of monic polynomials over a commutative ring
Authors: Yengui Ihsen 
Published: October 2003

AbstractGilmer and Heinzer proved that given a reduced ring R, a polynomial f divides a monic polynomial in R[X] if and only if there exists a direct sum decomposition of R = R0 ⊕ … ⊕ Rm (m ≤ deg f), associated to a fundamental system of idempotents e0, … , em, such that the component of f in each Ri[X] has degree coefficient which is a unit of Ri. We propose to give an algorithm to explicitly find such a decomposition. Moreover, we extend this result to divisors of doubly monic Laurent polynomials.