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‣ Clorfeniramina microinjetada no hipocampo dorsal reverte e efeito ansiolítico da L-histidina e prejudica a memória emocional de camundongos; Dorsal hippocampal microinjections of chlorpheniramine reverses anxiolitic-like effect of L-histidine and impairs mice emotional memory.

Souza, Lucas Canto de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 30/09/2011 Português
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O nosso grupo tem investigado os efeitos da Clorfeniramina (CPA), antagonista H1, e da L-histidina (LH), uma droga precursora da síntese de histamina, sobre a ansiedade e a memória emocional. Diante disso, os objetivos desse estudo foram investigar os efeitos LH administrada i.p. e da CPA microinjetada no hipocampo dorsal sobre a ansiedade e a memória emocional de camundongos submetidos ao labirinto em cruz elevado (LCE). O experimento foi realizado em dois dias consecutivos. No primeiro dia (T1) 71 camundongos machos da cepa Suíço-Albino pesando 25-35g foram pré-tratados i.p. com salina (SAL) ou LH (500mg/Kg). Após duas horas, os sujeitos receberam microinjeção de SAL ou CPA (0,016nmol; 0,052nmol; 0,16nmol/0,1l) no hipocampo dorsal. Após cinco minutos, os animais foram expostos ao LCE por cinco minutos. Vinte quatro horas depois, o mesmo protocolo experimental foi adotado na reexposição (T2). Os animais foram distribuídos aleatoriamente em 8 grupos de acordo com o tratamento farmacológico: SAL/SAL (n=9), SAL/CPA1 (n=9), SAL/CPA2 (n=10), SAL/CPA3 (n=8), LH/SAL (n=10), LH/CPA1 (n=8), LH/CPA2 (n=8) e LH/CPA3 (n=9). As três doses de CPA microinjetadas no hipocampo dorsal não alteraram a porcentagem de tempo gasto nos braços abertos (%TBA) na exposição ao LCE: T1 SAL/CPA1 (46...

‣ Determination of isoniazid in human urine using screen-printed carbon electrode modified with poly-L-histidine

Bergamini, Marcio F.; Santos, Daniela P.; Zanoni, Maria Valnice Boldrin
Fonte: Elsevier B.V. Sa Publicador: Elsevier B.V. Sa
Tipo: Artigo de Revista Científica Formato: 133-138
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Processo FAPESP: 03/06598-3; Processo FAPESP: 04/00111-8; A sensitive voltammetric method for trace measurements of isoniazid (INZ) in synthetic human urine sample is described. The method is based on its electroreduction at -0.98 V vs. Ag/AgCl on screen-printed carbon electrode (SPCE) modified with poly-L-histidine (PH). A film of good adherence on SPCE and electrocatalytic properties was obtained coating the electrode by histidine monomer electropolymerization process (SPCE/EPH). The electrochemical behavior of the modified SPCE was investigated by cyclic, linear sweep (LSV), differential pulse (DPV). square-wave voltammetry (SWV), and electrochemical impedance spectroscopy (EIS). Limits of detection of 5.0 x 10(-7) mol L(-1), 1.7 x 10(-7) mol L(-1) and 2.5 x 10(-7) mol L(-1) were estimated from LSV, DPV and SWV determinations, respectively. The method was successfully applied to the determination of INZ in human urine samples. (c) 2009 Elsevier B.V. All rights reserved.

‣ Screen-Printed Carbon Electrode Modified with Poly-L-histidine Applied to Gold(III) Determination

Bergamini, Marcio F.; Santos, Daniela P.; Zanoni, Maria Valnice Boldrin
Fonte: Soc Brasileira Quimica Publicador: Soc Brasileira Quimica
Tipo: Artigo de Revista Científica Formato: 100-106
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Processo FAPESP: 04/00111-8; Processo FAPESP: 03/06598-3; O presente trabalho reporta o desenvolvimento de um novo método voltamétrico para análise de íons ouro(III) usando eletrodo de carbono impresso modificado com poli-L-histidina. O procedimento é baseado no acúmulo do complexo [AuCl4]-, na superfície do eletrodo sob potencial de circuito aberto e tempo de acúmulo controlado. Parâmetros que influenciam na resposta, tais como: preparação do filme, pH, potencial de acúmulo e tempo de acúmulo, foram otimizados e curvas analíticas para os íons ouro foram construídas usando voltametria de varredura linear (LSV), pulso diferencial (DPV), e onda quadrada (SWV). Limites de detecção de 6,0 × 10-6 mol L-1, 1,7 × 10-6 mol L-1 e 4,0 × 10-6 mol L-1 foram obtidos para LSV, DPV e SWV, respectivamente. O método foi aplicado para a determinação de íons ouro em amostras de urina humana.; A sensitive voltammetric method for trace measurements of gold(III) ions using a screen-printed carbon electrode modified with poly-L-histidine is described. The new procedure is based on the accumulation of the tetrachloroaurates complex at the electrode surface under an open circuit potential condition...

‣ L-Histidine-europium(III) complex: A spectroscopical study

De Andrade Leite, Sergio R.; Couto Dos Santos, Marco A.; Carubelli, Célia R.; Galindo Massabni, Ana M.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 1185-1191
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Chemical characterization as well as spectroscopical study of the L-histidine-europium(III) complex were developed both experimental and theoretically. Molecular mechanics (MM) simulation was performed in order to have indication of the compound structure and the Eu 3+ chemical environment. The Simple Overlap Model (SOM) was applied to predict spectroscopic quantities as 5D 0→ 7F 0/ 5D 0→ 7F 2 intensity ratio, 5D 0→ 7F 1 transition splitting and the intensity Ω λ parameters (λ = 2 and 4). Satisfactory results are obtained with 0.1 and 2/3 as the effective charges of the nitrogen (gN) and oxygen (gO) respectively, and their polarizabilities (α) depend on the distance. © 1999 Elsevier Science B.V. All rights reserved.

‣ Electrochemical behavior and voltammetric determination of pyrazinamide using a poly-histidine modified electrode

Bergamini, Márcio F.; Santos, Daniela P.; Zanoni, Maria Valnice Boldrin
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 47-52
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Pyrazinamide (Pyrazinecarboxamide-PZA) is a drug that is used to treatment tuberculosis. In the present work, the voltammetric behavior of PZA was studied using a screen-printed modified electrode (SPCE). The modified electrode was constructed using poly-histidine films, and it showed an electrocatalytic effect, thus promoting a decrease in PZA reduction potential and improving the voltammetric response. Cyclic voltammetry and electrochemical impedance spectroscopy techniques have been employed in order to elucidate of the electrodic reaction. The results allowed the proposal that in the PZA reduction, a further chemical reaction occurs that corresponds to a second-order process which is subsequent to the electrode reaction. In addition, a sensitive voltammetric method was developed, and it was successfully applied for PZA determination in human urine samples. The best response was found using SPCE modified with poly-histidine prepared by histidine monomer electropolymerization (SPCE/EPH). The electroanalytical performance of the SPCE/EPH was investigated by linear sweep (LSV), differential pulse (DPV), and square wave voltammetry (SWV). A linear relationship between peak current and PZA concentrations was obtained from 9.0 × 10-7 to 1.0 × 10-4 mol L-1 by using DPV. The limit of detection at 5.7 × 10 -7 mol L-1 was estimated...

‣ Kinetic role of a histidine residue in the T1 copper site of the laccase from Rigidoporus lignosus

Vianello, Fabio; Miotto, Giovanni; Cambria, Maria Teresa; Lima, Giuseppina P. P.; Vanzani, Paola; Di Paolo, Maria Luisa
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 34-42
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Laccases (benzendiol:oxygen oxidoreductases; EC 1.10.3.2) catalyze the oxidation of a broad range of substrates, such as polyphenols, dyes and pollutants, and thus these enzymes are widely applied in industrial, biotechnological and environmental fields. In order to improve their biotechnological applications, a deep knowledge of structural factors involved in controlling their activity, in various experimental conditions and on different substrates, is required. In the present study, a laccase from the mushroom Rigidoporus lignosus was kinetically characterized. In particular, the stability, the effects of pH, ionic strength and fluoride ion concentration on the kinetic parameters were investigated, using three di-hydroxy-benzene isomers (1,2-dihydroxy-benzene, 1,3-dihydroxy-benzene and 1,4-dihydroxy-benzene) as substrates. The catalytic constant values of the laccase showed a bell-shaped pH profile, with the same optimum pH and pK(a) values for all tested substrates. This behavior appears to be due to the presence of an ionizable residue in the enzyme active site. To identify this residue, the enzyme was derivatized with diethylpyrocarbonate to modify accessible histidine residues, which, according to structural data, are present in the active site of this enzyme. The kinetic behavior of the derivatized laccase was compared with that of the native enzyme and the derivatized residues were identified by mass spectrometry. Mass spectrometry and kinetic results suggest the main role of His-457 in the control of the catalytic activity of laccase from R. lignosus. (C) 2013 Elsevier B.V. All rights reserved.

‣ Difração múltipla de raios-X no estudo das propriedades estruturais da L-histidina hidroclorídrica monohidratada; X-ray multiple diffraction in the study of the structural properties of L-histidine hydrochloride monohydrate

Alan Silva de Menezes
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 23/08/2006 Português
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Neste trabalho, o método baseado na variação nas posições angulares dos picos secundários em uma varredura Renninger da difração múltipla de raios-X usando radiação síncrotron foi utilizado para a determinação dos coeficientes piezelétricos da -histidina. HCl. H2O. A grande sensibilidade da técnica a pequenas deformações na célula unitária dos cristais analisados permite esta determinação, desde que o campo elétrico seja aplicado nas direções específicas escolhidas nas amostras. Foram determinados os parâmetros de rede da -histidina.HCl. H2O pura e dopada com Ni 2+, com boa precisão, a partir da escolha adequada dos picos secundários nas varreduras Renninger, e, também determinou-se o coeficiente d14 para a amostra dopada. Destes resultados foi observada uma contração do volume da célula unitária (0,04%) do cristal dopado em relação ao puro, resultado também obtido através do refinamento das amostras em forma de pó com o método de Rietveld. O efeito do Ni 2+ na rede da -histidina.HCl. H2O foi evidenciado na comparação entre as varreduras Renninger para os dois cristais, puro e dopado, através de mudanças na intensidade, posição angular e assimetria dos picos secundários, principalmente no pico correspondente ao caso de quatro-feixes (604)(404) simultâneos para a reflexão primária (10 0 0)...

‣ L-histidine reduces inhibitory avoidance in Carassius auratus submitted to cerebellar ablation

Garção,D.C.; Mattioli,R.
Fonte: Associação Brasileira de Divulgação Científica Publicador: Associação Brasileira de Divulgação Científica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2009 Português
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The effect of post-training treatment with L-histidine (LH) on the memory consolidation of inhibitory avoidance was investigated in Carassius auratus submitted to cerebellar ablation. The inhibitory avoidance procedure included 3 days: one habituation day, one training day (5 trials, T1-T5) and one test day. On the training day, each fish was placed individually in a white compartment separated from a black compartment by a sliding door. When the fish crossed into the black compartment, a weight was dropped in front of it (aversive stimulus) and the time to cross was recorded. Saline or LH (100 mg/kg) was injected intraperitoneally 10 min after the trials. Data were log10 transformed and analyzed by ANOVA and the Student-Newman-Keuls test (P < 0.05). In T5, all groups [ablation/LH (N = 15; 189.60 ± 32.52), ablation/saline (N = 14; 204.29 ± 28.95), sham/LH (N = 14; 232.36 ± 28.15), and sham/saline (N = 15; 249.07 ± 25.82)] had similar latencies that were significantly higher than T1 latencies [ablation/LH (89.33 ± 20.41), ablation/saline (97.00 ± 25.16), sham/LH (73.86 ± 18.42), and sham/saline (56.71 ± 17.59)], suggesting acquisition of inhibitory avoidance. For the test, there was a significant reduction in latencies of ablation/LH (61.53 ± 17.70) and sham/saline (52.79 ± 25.37) groups compared to the ablation/saline (213.64 ± 29.57) and sham/LH (199.43 ± 24.48) groups...

‣ L-histidine provokes a state-dependent memory retrieval deficit in mice re-exposed to the elevated plus-maze

Serafim,K.R.; Kishi,M.; Canto-de-Souza,A.; Mattioli,R.
Fonte: Associação Brasileira de Divulgação Científica Publicador: Associação Brasileira de Divulgação Científica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2010 Português
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The effects of L-histidine (LH) on anxiety and memory retrieval were investigated in adult male Swiss Albino mice (weight 30-35 g) using the elevated plus-maze. The test was performed on two consecutive days: trial 1 (T1) and trial 2 (T2). In T1, mice received an intraperitoneal injection of saline (SAL) or LH before the test and were then injected again and retested 24 h later. LH had no effect on anxiety at the dose of 200 mg/kg since there was no difference between the SAL-SAL and LH-LH groups at T1 regarding open-arm entries (OAE) and open-arm time (OAT) (mean ± SEM; OAE: 4.0 ± 0.71, 4.80 ± 1.05; OAT: 40.55 ± 9.90, 51.55 ± 12.10, respectively; P > 0.05, Kruskal-Wallis test), or at the dose of 500 mg/kg (OAE: 5.27 ± 0.73, 4.87 ± 0.66; OAT: 63.93 ± 11.72, 63.58 ± 10.22; P > 0.05, Fisher LSD test). At T2, LH-LH animals did not reduce open-arm activity (OAE and OAT) at the dose of 200 mg/kg (T1: 4.87 ± 0.66, T2: 5.47 ± 1.05; T1: 63.58 ± 10.22; T2: 49.01 ± 8.43 for OAE and OAT, respectively; P > 0.05, Wilcoxon test) or at the dose of 500 mg/kg (T1: 4.80 ± 1.60, T2: 4.70 ± 1.04; T1: 51.55 ± 12.10, T2: 43.88 ± 10.64 for OAE and OAT, respectively; P > 0.05, Fisher LSD test), showing an inability to evoke memory 24 h later. These data suggest that LH does not act on anxiety but does induce a state-dependent memory retrieval deficit in mice.

‣ Copper(II) mixed ligands complexes of hydroxamic acids with glycine, histamine and histidine

Fernandes,Maria Celina M.M.; Paniago,Eucler B.; Carvalho,Sandra
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/1997 Português
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A potentiometric and spectrophotometric study of physiologically interesting CuII mixed ligand complexes has been performed involving hydroxamic acids as primary ligands (A) and secondary ligands (B) represented either by histamine or the aminoacids glycine and histidine. All are potentially able to form chelate complexes with either five or six membered rings. The formation constant and the visible absorption spectrum were calculated for each one of the identified species, both binary and mixed ones. The most probable structures of the mixed species are discussed based upon their formation constants, their stabilization with regard to the two binary species as well as their visible absorption. It was evidenced that Cu-hydroxamate complexes do not favour significantly mixed ligand complex formation with aminoacids having only the carboxylate and amino groups; however, these complexes are strongly formed with histidine, due to the presence of the imidazol group.

‣ Screen-printed carbon electrode modified with poly-L-histidine applied to gold(III) determination

Bergamini,Márcio F.; Santos,Daniela P.; Zanoni,Maria Valnice B.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2009 Português
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A sensitive voltammetric method for trace measurements of gold(III) ions using a screen-printed carbon electrode modified with poly-L-histidine is described. The new procedure is based on the accumulation of the tetrachloroaurates complex at the electrode surface under an open circuit potential condition, followed by a cathodic stripping scan of potential. Parameters such as film preparation, pH, accumulation potential and deposition time have been optimized to obtain the best voltammetric response. Using optimal experimental conditions, analytical curves for gold ions were obtained using a linear sweep (LSV), differential pulse (DPV), and square wave voltammetry (SWV). Limits of detection of 6.0 × 10-6 mol L-1, 1.7 × 10-6 mol L-1 and 4.0 × 10-6 mol L-1 were estimated for the LSV, DPV and SWV, respectively. The method was successfully applied to the determination of gold ions in human urine samples.

‣ The role of histidine-rich glycoprotein in necrotic cell clearance and regulation of degradative enzymes

Poon, Ivan Ka Ho
Fonte: Universidade Nacional da Austrália Publicador: Universidade Nacional da Austrália
Tipo: Thesis (PhD); Doctor of Philosophy (PhD)
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Histidine-rich glycoprotein (HRG) is an abundant multi-functional protein that is present in the plasma of many vertebrates. HRG has a multi-domain structure that allows the molecule to interact with many ligands including heparin, heparan sulfate (HS), Fcy receptors (FcyR), plasminogen, fibrinogen, IgG, Clq, haem and Zn2+. The ability of HRG to interact with various ligands simultaneously has suggested that HRG can act as an adaptor molecule and regulate numerous biological processes such as immune complex/necrotic cell/pathogen clearance, cell adhesion, angiogenesis, coagulation and fibrinolysis. Although HRG is thought to play an important role in both immunity and vascular biology, the molecular mechanisms underpinning its action remain largely undefined. Thus, the aim of this thesis was to characterize the molecular components that are involved in HRG-mediated uptake of necrotic cells and to further examine the role of HRG in regulating degradative enzymes, such as plasminogen/plasmin and heparanase...In summary, the studies presented in this thesis have delineated the molecular mechanisms underlying necrotic cell removal mediated by plasma-derived HRG and may have important implications for the development of autoimmune disease caused by defective clearance of dying/dead cells. In addition...

‣ Plasminogen is tethered with high affinity to the cell surface by the plasma protein, histidine-rich glycoprotein

Jones, Allison; Hulett, Mark; Altin, Joseph; Hogg, Phillip; Parish, Christopher
Fonte: American Society for Biochemistry and Molecular Biology Inc Publicador: American Society for Biochemistry and Molecular Biology Inc
Tipo: Artigo de Revista Científica
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Plasminogen has been implicated in extracellular matrix degradation by invading cells, but few high affinity cell surface receptors for the molecule have been identified. Previous studies have reported that the plasma protein, histidine-rich glycoprotein

‣ Conversion of the Escherichia coli Cytochrome b562 to an Archetype Cytochrome b: A Mutant with Bis-Histidine Ligation of Heme Iron

Hay, Sam; Wydrzynski, Thomas
Fonte: American Chemical Society Publicador: American Chemical Society
Tipo: Artigo de Revista Científica
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A mutant of the Escherichia coli cytochrome b562 has been created in which the heme-ligating methionine (Met) at position 7 has been replaced with a histidine (His) (M7H). This protein is a double mutant that also has the His 63 to asparagine (H63N) mutation, which removes a solvent-exposed His. While the H63N mutation has no measurable effect on the cytochrome, the M7H mutation converts the atypical His/Met heme ligation in cytochrome b 562 to the classic cytochrome b-type bis-His ligation. This mutation has little effect on the Kd of heme binding but significantly reduces the chemical and thermal stability of the mutant cytochrome relative to the wild type (wt). Both proteins have similar absorbance (Abs) and electron paramagnetic resonance (EPR) properties characteristic of 6-coordinate low-spin heme. The Abs spectra of the oxidized and reduced bis-His cytochrome are slightly blue-shifted relative to the wt, and the α Abs band of ferrous M7H mutant is unusually split. The M7H mutation decreases the midpoint potential of the bound heme by 260 mV at pH 7 and considerably alters the pH dependence of the Em, which becomes dominated by a single pKred = 6.8.

‣ Binding of Zn-Chlorin to a synthetic four-helix bundle peptide through histidine ligation

Razeghifard, Mohammad; Wydrzynski, Thomas
Fonte: American Chemical Society Publicador: American Chemical Society
Tipo: Artigo de Revista Científica
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We have used a two histidine-containing synthetic peptide (Sharp et al. (1998) Proc. Natl. Acad. Sci. U.S.A. 95, 10465-10470) as a scaffold to bind Zn(II) chorin e6 (ZnCe6) through histidine ligation. Protocols for the preparation and purification of the

‣ Histidine-rich glycoprotein regulates the binding of monomeric IgG and immune complexes by moncytes

Gorgani, Nick; Altin, Joseph; Parish, Christopher
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
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Histidine-rich glycoprotein (HRG) is a relatively abundant plasma protein which we have shown previously inhibits the formation of insoluble immune complexes (IC). In this study we examined the ability of HRG to regulate the binding of monomeric IgG and IC to monocytes. Initial studies demonstrated that HRG interacts with FcγRI on the monocytic cell line THP1 and blocks the binding of monomeric IgG to these cells. However, despite totally blocking the binding of monomeric IgG to FcγRI, pre-incubation of THP1 cells with HRG had no effect on the binding of IC to these cells. In contrast, depending on the HRG:IgG molar ratio, pre-incubation of monomeric IgG with HRG resulted in either enhanced or reduced IgG binding to FcγRI. Similarly, under certain highly defined conditions, incorporation of HRG in IgG-containing IC potentiated the binding of IC to THP1 cells. The key conditions involved incorporating approximately equimolar concentrations of HRG and IgG in the IC, the IC being formed at a near equivalence antigen:antibody ratio and usually physiological concentration (20 μM) of Zn2+ being present. Collectively these observations indicate that HRG is an important regulator of IC uptake by monocytes. Thus HRG can interact with FcγRI on monocytes and block monomeric IgG binding...

‣ Histidine-rich glycoprotein: A novel adaptor protein in plasma that modulates the immune, vascular and coagulation systems

Jones, Allison; Hulett, Mark; Parish, Christopher
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
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Histidine-rich glycoprotein (HRG) is an abundant plasma glycoprotein that has a multidomain structure, interacts with many ligands, and has been shown to regulate a number of important biological processes. HRG ligands include Zn2+ and haem, tropomyosin,

‣ Histidine-rich glycoprotein specifically binds to necrotic cells via its amino-terminal domain and facilitates necrotic cell phagocytosis

Jones, Allison; Poon, Ivan; Hulett, Mark; Parish, Christopher
Fonte: Japanese Biochemical Society Publicador: Japanese Biochemical Society
Tipo: Artigo de Revista Científica
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Cells that become necrotic or apoptotic through tissue damage or during normal cellular turnover are usually rapidly cleared from the circulation and tissues by phagocytic cells. A number of soluble proteins have been identified that facilitate the phagocytosis of apoptotic cells, but few proteins have been defined that selectively opsonize necrotic cells. Previous studies have shown that histidine-rich glycoprotein (HRG), an abundant (∼100 μg/ml) 75-kDa plasma glycoprotein, binds to cell surface heparan sulfate on viable cells and cross-links other ligands, such as plasminogen, to the cell surface. In this study we have demonstrated that HRG also binds very strongly, in a heparan sulfate-independent manner, to cytoplasmic ligand(s) exposed in necrotic cells. This interaction is mediated by the amino-terminal domain of HRG and results in enhanced phagocytosis of the necrotic cells by a monocytic cell line. In contrast, it was found that HRG binds poorly to and does not opsonize early stage apoptotic cells. Thus, HRG has the unique property of selectively recognizing necrotic cells and may play an important physiological role in vivo by facilitating the uptake and clearance of necrotic, but not apoptotic, cells by phagocytes.

‣ Murine histidine-rich glycoprotein: Cloning, characterisation and cellular origin

Hulett, Mark; Parish, Christopher
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
Português
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Histidine-rich glycoprotein (HRG) is a plasma protein of vertebrates that has been implicated in the regulation of several important biological functions, including the immune response and blood clotting. In the present study, we have isolated and determined the sequence of the cDNAs for both mouse and rat HRG. The deduced amino acid sequences of mouse and rat HRG are 525 and 510 amino acids, respectively, and they show the same three-domain structure that has been predicted for human HRG, with which they share high amino acid identity. Northern blot analysis indicates that the mouse HRG mRNA is 1.7 kb and is localized specifically to the liver. It has been suggested, somewhat controversially, that some immune cells, such as monocytes and megakaryocytes, also synthesize HRG. Reverse transcriptase-polymerase chain reaction analysis has failed to show any HRG mRNA in immune tissues of the mouse, including the spleen, thymus, lymph node, bone marrow and peripheral blood leucocytes. These data suggest that HRG expression by immune cells is due to the acquisition of plasma HRG derived from the liver. Finally, genomic Southern blot analysis of the mouse HRG gene suggests that it is a single copy gene.

‣ The evaluation of peptide/histidine transporter 1 (PHT1) function: uptake kinetics utilizing a cos-7 stably transfected cell line

Lindley,David J.; Carl,Stephen M.; Mowery,Stephanie A.; Knipp,Gregory T.
Fonte: Asociación Farmacéutica Mexicana A.C. Publicador: Asociación Farmacéutica Mexicana A.C.
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2011 Português
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There have been relatively few studies focused on the proton-dependent oligopeptide transporter (POT) superfamily member, Peptide/Histidine Transporter 1 (PHT1), with respect to its contribution to the ADME of peptides and peptide-based drugs. These studies were conducted to determine hPHT1-mediated, H+-dependent uptake kinetics of histidine, carnosine, Gly-Sar and valacyclovir in stably transfected hPHT1-COS-7 cells comparative to kinetics determined in an empty vector (Mock) stably transfected cell line. The results suggest that Gly-Sar appears to be a substrate for PHT1 based on efflux from the stably transfected hPHT1 COS-7 cells. Histidine and Gly-Sar concentration- and time-dependent studies suggest mixed-uptake kinetics. These studies suggest that stably transfected hPHT1-COS-7 cells exhibit different uptake kinetics than those observed in our previous studies and illustrate the requirement for experiments to delineate the physiological role of hPHT1.