26 results on '"Klüver E"'
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2. Ein neues Mangan(II)-Oxowolframat: Mn3WO6.
- Author
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Klüver, E. and Müller-Buschbaum, Hk.
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- 1994
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3. Ein neues Oxometallat mit Mangan(II): Ba5Mn4Nd8O21.
- Author
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Müller-Buschbaum, Hk. and Klüver, E.
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- 1992
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4. Über eine neu entdeckte Dimorphie an BaCoEr2O5.
- Author
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Klüver, E. and Müller-Buschbaum, Hk.
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- 1993
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5. Die erste Verbindung mit Mn2+ der Stoffklasse BaMLn2O5: BaMnDy2O5.
- Author
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Müller-Buschbaum, Hk. and Klüver, E.
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- 1992
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6. Zwei weitere Oxometallate zum Ba 5Mn 4Ln 8O 21-Typ: Ba 5Mn 4Sm 8O 21 und Ba 5Mn 4Ho 8O 21
- Author
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Klüver, E., Peters, E., and Müller-Buschbaum, Hk.
- Published
- 1992
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7. Zur kristallchemie von BaNiPr 2O 5 und BaMn 0,36Mg 0,64Nd 2O 5
- Author
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Klüver, E. and Müller-Buschbaum, Hk.
- Published
- 1994
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8. About 3D Printability of Thermoplastic Collagen for Biomedical Applications.
- Author
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Passos M, Zankovic S, Minas G, Klüver E, Baltzer M, Schmal H, and Seidenstuecker M
- Abstract
With more than 1.5 million total knee and hip implants placed each year, there is an urgent need for a drug delivery system that can effectively support the repair of bone infections. Scaffolds made of natural biopolymers are widely used for this purpose due to their biocompatibility, biodegradability, and suitable mechanical properties. However, the poor processability is a bottleneck, as highly customizable scaffolds are desired. The aim of the present research is to develop a scaffold made of thermoplastic collagen (TC) using 3D printing technology. The viscosity of the material was measured using a rheometer. A 3D bioplotter was used to fabricate the scaffolds out of TC. The mechanical properties of the TC scaffolds were performed using tension/compression testing on a Zwick/Roell universal testing machine. TC shows better compressibility with increasing temperature and a decrease in dynamic viscosity (η), storage modulus (G'), and loss modulus (G″). The compressive strength of the TC scaffolds was between 3-10 MPa, depending on the geometry (cylinder or cuboid, with different infills). We have demonstrated for the first time that TC can be used to fabricate porous scaffolds by 3D printing in various geometries.
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- 2022
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9. Additive Manufacturing with Thermoplastic Collagen.
- Author
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Klüver E, Baltzer M, Langer A, and Meyer M
- Abstract
Thermoplastic collagen is a partially denatured collagen powder which can be processed by thermoplastic methods such as extrusion and injection molding, but was hitherto not adapted for the use in additive manufacturing (AM) techniques. This paper describes the first successful application of collagen/water/glycerol mixtures in an AM process using a BioScaffolder 3.2 from GeSiM mbH. Strands of molten collagen were deposited onto a building platform forming differently shaped objects. The collagen melt was characterized rheologically and optimal processing conditions were established. The technique includes the use of supporting structures of PLA/wood composite for samples with complex geometry as well as post-processing steps such as the removal of the supporting structure and manual surface smoothing. The manufactured objects are characterized concerning water solubility, swelling behavior and compressibility. Possible applications are in the non-medical sector and include collagen-based pet food or customized organ models for medical training.
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- 2022
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10. Synthesis and structure-activity relationship of beta-defensins, multi-functional peptides of the immune system.
- Author
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Klüver E, Adermann K, and Schulz A
- Subjects
- Amino Acid Sequence, Animals, Anti-Infective Agents chemistry, Anti-Infective Agents pharmacology, Humans, Microbial Sensitivity Tests, Models, Molecular, Molecular Sequence Data, Sequence Homology, Amino Acid, Structure-Activity Relationship, beta-Defensins chemistry, beta-Defensins pharmacology, Anti-Infective Agents chemical synthesis, beta-Defensins chemical synthesis
- Abstract
beta-defensins are a large family of multiple disulfide-bonded peptides occurring in mammals and birds. They play an important role in the innate immune system, directly killing microbial organisms. Recent research has demonstrated that beta-defensins are important for other biological functions beyond antimicrobial effects, including inhibition of viral infection, interaction with Toll-like receptors, chemotactic effects, and sperm function. The corresponding broad spectrum of activities makes this peptide class an important subject and tool in immunologic research. In this review, we summarize the current status of the routes to obtain synthetic beta-defensins, their major structural properties and structure-activity relationship., (Copyright 2006 European Peptide Society and John Wiley & Sons, Ltd.)
- Published
- 2006
- Full Text
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11. Structure-activity relation of human beta-defensin 3: influence of disulfide bonds and cysteine substitution on antimicrobial activity and cytotoxicity.
- Author
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Klüver E, Schulz-Maronde S, Scheid S, Meyer B, Forssmann WG, and Adermann K
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- Amino Acid Sequence, Cell Line, Tumor, Cell Survival drug effects, Circular Dichroism, Cytotoxins chemical synthesis, Cytotoxins toxicity, Gram-Negative Bacteria drug effects, Gram-Negative Bacteria growth & development, Gram-Positive Bacteria drug effects, Gram-Positive Bacteria growth & development, Hemoglobins metabolism, Hemolysis drug effects, Humans, Hydrophobic and Hydrophilic Interactions, Microbial Sensitivity Tests, Molecular Sequence Data, Protein Structure, Secondary, Structure-Activity Relationship, beta-Defensins chemical synthesis, Amino Acid Substitution, Cysteine chemistry, Cytotoxins chemistry, Disulfides chemistry, beta-Defensins chemistry, beta-Defensins toxicity
- Abstract
Human beta-defensins form a group of cysteine-rich antimicrobial peptides which have been found in epithelial tissue and, more recently, in the male genital tract. They play a role in the defense against microbial pathogens in innate immunity and display additional chemotactic functions in the adaptive immune system. An important characteristic of antimicrobial peptides is that they also exhibit toxic potential on eukaryotic cells. Very little is known about the structure dependence of antimicrobial and cytotoxic effects. We investigated human beta-defensin 3 (hBD-3), a potent broad-spectrum antimicrobial effector peptide, regarding the influence of structural parameters on the antimicrobial and cytotoxic activity. We have established a structure-activity relation of the hBD-3 using synthetic derivatives differing in length, charge, disulfide connectivity, and overall hydrophobicity. The antimicrobial activity of the peptides was compared to the cyctotoxic effects on monocytic THP-1 cells and the hemolytic activity on human erythrocytes. We found that it is not important for antimicrobial and cytotoxic activity whether and how cysteine residues are arranged to form disulfide bonds. Substitution of half-cystinyl residues by tryptophan resulted in increased activities, while other substitutions did not change activity. Correlation of activities with the structural changes demonstrates that the activity on eukaryotic cells appears to depend strongly on the overall hydrophobicity. In contrast, the antimicrobial potency of hBD-3 peptides is determined by the distribution of positively charged amino acid residues and hydrophobic side chains. The results facilitate the understanding of beta-defensin interaction with different cell types and guide the design of antimicrobially active peptides.
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- 2005
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12. Engineering disulfide bonds of the novel human beta-defensins hBD-27 and hBD-28: differences in disulfide formation and biological activity among human beta-defensins.
- Author
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Schulz A, Klüver E, Schulz-Maronde S, and Adermann K
- Subjects
- Amino Acid Sequence, Cysteine, Humans, Molecular Sequence Data, Peptide Fragments chemistry, Sequence Alignment, Sequence Homology, Amino Acid, beta-Defensins chemical synthesis, Disulfides chemistry, beta-Defensins chemistry
- Abstract
Human beta-defensins comprise a large number of peptides that play a functional role in the innate and adaptive immune system. Recently, clusters of new beta-defensin genes with predominant expression in testicular tissue have been discovered on different chromosomes by bioinformatics. beta-Defensins share a common pattern of three disulfides that are essential for their biological effects. Here we report for the first time the chemical synthesis of the new fully disulfide-bonded beta-defensins hBD-27 and hBD-28, and compare the results with synthetic procedures to obtain the known hBD-2 and hBD-3. While hBD-27 was readily converted into a product with the desired disulfide pattern by oxidative folding, hBD-28 required a selective protective group strategy to introduce the three disulfide bonds. The established synthetic processes were applied to the synthesis of hBD-2, which, like hBD-27, was accessible by oxidative folding, whereas hBD-3 required a selective strategy comparable to hBD-28. Experimental work demonstrated that trityl, acetamidomethyl, and t-butyl are superior to other protection strategies. However, the suitable pairwise arrangement of the protective groups can be different, as shown here for hBD-3 and hBD-28. Determination of the minimum inhibitory concentration against different bacteria revealed that hBD-27, in contrast to other beta-defensins tested, has virtually no antimicrobial activity. Compared to the other peptides tested, hBD-27 showed almost no cytotoxic activity, measured by hemoglobin release of erythrocytes. This might be due to the low positive net charge, which is significantly higher for hBD-2, hBD-3, and hBD-28., (2004 Wiley Periodicals, Inc)
- Published
- 2005
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13. Stability and cleavage conditions of (2-furyl)-L-alanine-containing peptides.
- Author
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Schulz A, Busmann A, Klüver E, Schnebel M, and Adermann K
- Subjects
- Chromatography, High Pressure Liquid, Ethyl Ethers metabolism, Silanes metabolism, Sulfhydryl Compounds metabolism, Trifluoroacetic Acid, Alanine analogs & derivatives, Peptide Fragments metabolism
- Abstract
The furyl group of (2-furyl)-L-alanine-containing peptides obtained from Fmoc solid-phase synthesis is partially degraded to several by-products during the final TFA-mediated deprotection in the presence of cation scavengers such as ethanedithiol and propanedithiol. The major by-product corresponds to a bis-dithioacetale formed after acidic hydrolysis of the furyl group. We examined several cleavage conditions and found that cleavage cocktails containing water and triisopropylsilane or 3,6-dioxa-1,8-octanedithiol (DODT) in trifluoroacetic acid are sufficient to minimize the side reaction.
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- 2004
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14. Isolation and biochemical characterization of LEAP-2, a novel blood peptide expressed in the liver.
- Author
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Krause A, Sillard R, Kleemeier B, Klüver E, Maronde E, Conejo-García JR, Forssmann WG, Schulz-Knappe P, Nehls MC, Wattler F, Wattler S, and Adermann K
- Subjects
- Alternative Splicing, Amino Acid Sequence, Animals, Anti-Infective Agents isolation & purification, Anti-Infective Agents pharmacology, Antimicrobial Cationic Peptides genetics, Antimicrobial Cationic Peptides isolation & purification, Antimicrobial Cationic Peptides pharmacology, Base Sequence, Blood Proteins genetics, Blood Proteins isolation & purification, Blood Proteins pharmacology, Cloning, Molecular, DNA, Complementary genetics, Disulfides chemistry, Dose-Response Relationship, Drug, Hemofiltration, Humans, Microbial Sensitivity Tests, Molecular Sequence Data, Organ Specificity, Saccharomyces cerevisiae drug effects, Sequence Alignment, Spectrometry, Mass, Electrospray Ionization, Anti-Infective Agents chemistry, Antimicrobial Cationic Peptides chemistry, Blood Proteins chemistry, Liver metabolism
- Abstract
The human genome contains numerous genes whose protein products are unknown in terms of structure, interaction partner, expression, and function. To unravel the function of these orphan genes, it is of particular value to isolate native forms of protein and peptide products derived from these genes. From human blood ultrafiltrate, we characterized a novel gene-encoded, cysteine-rich, and cationic peptide that we termed liver-expressed antimicrobial peptide 2 (LEAP-2). We identified several circulating forms of LEAP-2 differing in their amino-terminal length, all containing a core structure with two disulfide bonds formed by cysteine residues in relative 1-3 and 2-4 positions. Molecular cloning of the cDNA showed that LEAP-2 is synthesized as a 77-residue precursor, which is predominantly expressed in the liver and highly conserved among mammals. This makes it a unique peptide that does not exhibit similarity with any known human peptide regarding its primary structure, disulfide motif, and expression. Analysis of the LEAP-2 gene resulted in the identification of an alternative promoter and at least four different splicing variants, with the two dominating transcripts being tissue-specifically expressed. The largest native LEAP-2 form of 40 amino acid residues is generated from the precursor at a putative cleavage site for a furin-like endoprotease. In contrast to smaller LEAP-2 variants, this peptide exhibited dose-dependent antimicrobial activity against selected microbial model organisms. LEAP-2 shares some characteristic properties with classic peptide hormones and it is expected that the isolation of this novel peptide will help to unravel its physiological role.
- Published
- 2003
- Full Text
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15. Chemical synthesis of beta-defensins and LEAP-1/hepcidin.
- Author
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Klüver E, Schulz A, Forssmann WG, and Adermann K
- Subjects
- Amino Acid Sequence, Animals, Antimicrobial Cationic Peptides chemistry, Chromatography, High Pressure Liquid, Disulfides chemistry, Hepcidins, Humans, Mice, Molecular Sequence Data, Oligopeptides chemical synthesis, Oligopeptides chemistry, Protein Folding, Proteins chemistry, beta-Defensins chemistry, Antimicrobial Cationic Peptides chemical synthesis, Proteins chemical synthesis, beta-Defensins chemical synthesis
- Abstract
A large and steadily growing subfamily of antimicrobially active peptides of animals and plants is formed by the defensins, which are highly disulfide-bonded, cationic peptides with a molecular mass of about 4 kDa. The synthesis of the human beta-defensins 1 and 2 (hBD-1, hBD-2) as well as of the novel murine beta-defensins 7 and 8 (mBD-7 and mBD-8) is reported. The peptides were synthesized by solid-phase peptide synthesis using fluorenylmethoxycarbonyl chemistry. The linear products were oxidized in the presence of the cysteine/cystine redox system to the biologically active molecules. The correct disulfide connectivity of the resulting cyclic products was partly verified by mass spectrometry and sequence analysis of the fragments obtained after tryptic cleavage. In addition, the recently discovered antimicrobially active human peptide LEAP-1/hepcidin, which contains four disulfide bonds, was successfully synthesized and subsequently oxidized. For Liver-expressed anti microbial peptide (LEAP)-1/hepcidin and hBD-1, the identity of native and synthetic peptides was demonstrated by high-pressure liquid chromatography and capillary electrophoretic analysis. The general synthetic procedure is suitable to rapidly perform the total chemical synthesis of novel fully bioactive defensins, which are expected to be identified soon, as well as of structurally modified analogs.
- Published
- 2002
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16. Hemofiltrate CC chemokine 1[9-74] causes effective internalization of CCR5 and is a potent inhibitor of R5-tropic human immunodeficiency virus type 1 strains in primary T cells and macrophages.
- Author
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Münch J, Ständker L, Pöhlmann S, Baribaud F, Papkalla A, Rosorius O, Stauber R, Sass G, Heveker N, Adermann K, Escher S, Klüver E, Doms RW, Forssmann WG, and Kirchhoff F
- Subjects
- Antigens, Surface biosynthesis, Cells, Cultured, Chemokine CCL1, Chemokine CCL5 pharmacology, Dose-Response Relationship, Drug, Down-Regulation drug effects, Flow Cytometry, HIV-1 genetics, Humans, Microscopy, Fluorescence, Protein Binding, Structure-Activity Relationship, Subcellular Fractions metabolism, Subcellular Fractions virology, Virus Replication drug effects, Anti-HIV Agents pharmacology, CCR5 Receptor Antagonists, Chemokines, CC pharmacology, HIV-1 drug effects, Macrophages virology, Peptide Fragments pharmacology, T-Lymphocytes virology
- Abstract
Proteolytic processing of the abundant plasmatic human CC chemokine 1 (HCC-1) generates a truncated form, HCC-1[9-74], which is a potent agonist of CCR1, CCR3, and CCR5; promotes calcium influx and chemotaxis of T lymphoblasts, monocytes, and eosinophils; and inhibits infection by CCR5-tropic human immunodeficiency virus type 1 (HIV-1) isolates. In the present study we demonstrate that HCC-1[9-74] interacts with the second external loop of CCR5 and inhibits replication of CCR5-tropic HIV-1 strains in both primary T cells and monocyte-derived macrophages. Low concentrations of the chemokine, however, frequently enhanced the replication of CCR5-tropic HIV-1 isolates but not the replication of X4-tropic HIV-1 isolates. Only HCC-1[9-74] and HCC-1[10-74], but not other HCC-1 length variants, displayed potent anti-HIV-1 activities. Fluorescence-activated cell sorter analysis revealed that HCC-1[9-74] caused up to 75% down-regulation of CCR5 cell surface expression, whereas RANTES (regulated on activation, normal T-cell expressed and secreted) achieved a reduction of only about 40%. Studies performed with green fluorescent protein-tagged CCR5 confirmed that both HCC-1[9-74] and RANTES, but not full-length HCC-1, mediated specific internalization of the CCR5 HIV-1 entry cofactor. Our results demonstrate that the interaction with HCC-1[9-74] causes effective intracellular sequestration of CCR5, but they also indicate that the effect of HCC-1[9-74] on viral replication is subject to marked cell donor- and HIV-1 isolate-dependent variations.
- Published
- 2002
- Full Text
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17. Structure determination of human and murine beta-defensins reveals structural conservation in the absence of significant sequence similarity.
- Author
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Bauer F, Schweimer K, Klüver E, Conejo-Garcia JR, Forssmann WG, Rösch P, Adermann K, and Sticht H
- Subjects
- Amino Acid Sequence, Animals, Chromatography, Conserved Sequence, Crystallography, X-Ray, Disulfides, Humans, Magnetic Resonance Spectroscopy, Mice, Models, Molecular, Molecular Sequence Data, Peptides chemistry, Protein Conformation, Protein Folding, Protein Structure, Secondary, Protein Structure, Tertiary, Sequence Homology, Amino Acid, beta-Defensins chemistry
- Abstract
Defensins are cationic and cysteine-rich peptides that play a crucial role in the host defense against microorganisms of many organisms by their capability to permeabilize bacterial membranes. The low sequence similarity among the members of the large mammalian beta-defensin family suggests that their antimicrobial activity is largely independent of their primary structure. To investigate to what extent these defensins share a similar fold, the structures of the two human beta-defensins, hBD-1 and hBD-2, as well as those of two novel murine defensins, termed mBD-7 and mBD-8, were determined by nuclear magnetic resonance spectroscopy. All four defensins investigated share a striking similarity on the level of secondary and tertiary structure including the lack of a distinct hydrophobic core, suggesting that the fold is mainly stabilized by the presence of three disulfide bonds. In addition to the overall shape of the molecules, the ratio of solvent-exposed polar and hydrophobic side chains is also very similar among the four defensins investigated. It is significant that beta-defensins do not exhibit a common pattern of charged and hydrophobic residues on the protein surface and that the beta-defensin-specific fold appears to accommodate a wide range of different amino acids at most sequence positions. In addition to the implications for the mode of biological defensin actions, these findings are of particular interest because beta-defensins have been suggested as lead compounds for the development of novel peptide antibiotics for the therapy of infectious diseases.
- Published
- 2001
- Full Text
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18. Identification of a novel, multifunctional beta-defensin (human beta-defensin 3) with specific antimicrobial activity. Its interaction with plasma membranes of Xenopus oocytes and the induction of macrophage chemoattraction.
- Author
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García JR, Jaumann F, Schulz S, Krause A, Rodríguez-Jiménez J, Forssmann U, Adermann K, Klüver E, Vogelmeier C, Becker D, Hedrich R, Forssmann WG, and Bals R
- Subjects
- Amino Acid Sequence, Animals, Anti-Bacterial Agents chemistry, Anti-Bacterial Agents metabolism, Burkholderia cepacia drug effects, Cell Line, Epithelial Cells physiology, Gene Expression Regulation, Humans, Ion Channels metabolism, Molecular Sequence Data, Monocytes drug effects, Monocytes metabolism, Oocytes, Patch-Clamp Techniques, Sequence Alignment, Xenopus laevis, beta-Defensins chemistry, beta-Defensins genetics, Anti-Bacterial Agents pharmacology, Cell Membrane metabolism, Chemotaxis physiology, Macrophages physiology, beta-Defensins metabolism, beta-Defensins pharmacology
- Abstract
Previous studies have shown the implication of beta-defensins in host defense of the human body. The human beta-defensins 1 and 2 (hBD-1, hBD-2) have been isolated by biochemical methods. Here we report the identification of a third human beta-defensin, called human beta-defensin 3 (hBD-3; cDNA sequence, Genbank accession no. AF295370), based on bioinformatics and functional genomic analysis. Expression of hBD-3 is detected throughout epithelia of many organs and in non-epithelial tissues. In contrast to hBD-2, which is upregulated by microorganisms or tumor necrosis factor-alpha (TNF-alpha), hBD-3 expression is increased particularly after stimulation by interferon-gamma. Synthetic hBD-3 exhibits a strong antimicrobial activity against gram-negative and gram-positive bacteria and fungi, including Burkholderia cepacia. In addition, hBD-3 activates monocytes and elicits ion channel activity in biomembranes, specifically in oocytes of Xenopus laevis. This paper also shows that screening of genomic sequences is a valuable tool with which to identify novel regulatory peptides. Human beta-defensins represent a family of antimicrobial peptides differentially expressed in most tissues, regulated by specific mechanisms, and exerting physiological functions not only related to direct host defense.
- Published
- 2001
- Full Text
- View/download PDF
19. Human beta-defensin 4: a novel inducible peptide with a specific salt-sensitive spectrum of antimicrobial activity.
- Author
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García JR, Krause A, Schulz S, Rodríguez-Jiménez FJ, Klüver E, Adermann K, Forssmann U, Frimpong-Boateng A, Bals R, and Forssmann WG
- Subjects
- Amino Acid Sequence, Anti-Bacterial Agents, Anti-Infective Agents chemistry, Chemotactic Factors, DNA, Complementary chemistry, Drug Synergism, Epithelial Cells metabolism, Escherichia coli drug effects, Gene Expression, Humans, Lung metabolism, Molecular Sequence Data, Monocytes, Pseudomonas Infections metabolism, RNA, Messenger analysis, Reverse Transcriptase Polymerase Chain Reaction, Saccharomyces cerevisiae drug effects, Staphylococcus drug effects, Streptococcal Infections metabolism, Tetradecanoylphorbol Acetate pharmacology, beta-Defensins chemistry, beta-Defensins genetics, Anti-Infective Agents pharmacology, beta-Defensins pharmacology
- Published
- 2001
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