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Hasenmayer D, Lamontagne A, Lewitt L, Oner S, Buchholz K, Tran K, Rojas Levine J, Brennan A, Fox E, Ngo S, McKenna S, Plesa G, Siegel D. Implementation of new cell washing technology in an academic cell therapy manufacturing laboratory. Cytotherapy 2021. [DOI: 10.1016/s1465324921005570] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Schuh AK, Rahbari M, Heimsch KC, Mohring F, Gabryszewski SJ, Weder S, Buchholz K, Rahlfs S, Fidock DA, Becker K. Stable Integration and Comparison of hGrx1-roGFP2 and sfroGFP2 Redox Probes in the Malaria Parasite Plasmodium falciparum. ACS Infect Dis 2018; 4:1601-1612. [PMID: 30129748 DOI: 10.1021/acsinfecdis.8b00140] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Studying redox metabolism in malaria parasites is of great interest for understanding parasite biology, parasite-host interactions, and mechanisms of drug action. Genetically encoded fluorescent redox sensors have recently been described as powerful tools for determining the glutathione-dependent redox potential in living parasites. In the present study, we genomically integrated and expressed the ratiometric redox sensors hGrx1-roGFP2 (human glutaredoxin 1 fused to reduction-oxidation sensitive green fluorescent protein) and sfroGFP2 (superfolder roGFP2) in the cytosol of NF54- attB blood-stage Plasmodium falciparum parasites. Both sensors were evaluated in vitro and in cell culture with regard to their fluorescence properties and reactivity. As genomic integration allows for the stable expression of redox sensors in parasites, we systematically compared single live-cell imaging with plate reader detection. For these comparisons, short-term effects of redox-active compounds were analyzed along with mid- and long-term effects of selected antimalarial agents. Of note, the single components of the redox probes themselves did not influence the redox balance of the parasites. Our analyses revealed comparable results for both the hGrx1-roGFP2 and sfroGFP2 probes, with sfroGFP2 exhibiting a more pronounced fluorescence intensity in cellulo. Accordingly, the sfroGFP2 probe was employed to monitor the fluorescence signals throughout the parasites' asexual life cycle. Through the use of stable genomic integration, we demonstrate a means of overcoming the limitations of transient transfection, allowing more detailed in-cell studies as well as high-throughput analyses using plate reader-based approaches.
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Affiliation(s)
- Anna Katharina Schuh
- Biochemistry and Molecular Biology, Interdisciplinary Research Center, Justus Liebig University Giessen, 35392 Giessen, Germany
| | - Mahsa Rahbari
- Biochemistry and Molecular Biology, Interdisciplinary Research Center, Justus Liebig University Giessen, 35392 Giessen, Germany
| | - Kim C. Heimsch
- Biochemistry and Molecular Biology, Interdisciplinary Research Center, Justus Liebig University Giessen, 35392 Giessen, Germany
| | - Franziska Mohring
- Biochemistry and Molecular Biology, Interdisciplinary Research Center, Justus Liebig University Giessen, 35392 Giessen, Germany
| | | | - Stine Weder
- Biochemistry and Molecular Biology, Interdisciplinary Research Center, Justus Liebig University Giessen, 35392 Giessen, Germany
| | - Kathrin Buchholz
- Biochemistry and Molecular Biology, Interdisciplinary Research Center, Justus Liebig University Giessen, 35392 Giessen, Germany
| | - Stefan Rahlfs
- Biochemistry and Molecular Biology, Interdisciplinary Research Center, Justus Liebig University Giessen, 35392 Giessen, Germany
| | | | - Katja Becker
- Biochemistry and Molecular Biology, Interdisciplinary Research Center, Justus Liebig University Giessen, 35392 Giessen, Germany
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Pelle KG, Oh K, Buchholz K, Narasimhan V, Joice R, Milner DA, Brancucci NM, Ma S, Voss TS, Ketman K, Seydel KB, Taylor TE, Barteneva NS, Huttenhower C, Marti M. Transcriptional profiling defines dynamics of parasite tissue sequestration during malaria infection. Genome Med 2015; 7:19. [PMID: 25722744 PMCID: PMC4342211 DOI: 10.1186/s13073-015-0133-7] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Accepted: 01/15/2015] [Indexed: 01/23/2023] Open
Abstract
BACKGROUND During intra-erythrocytic development, late asexually replicating Plasmodium falciparum parasites sequester from peripheral circulation. This facilitates chronic infection and is linked to severe disease and organ-specific pathology including cerebral and placental malaria. Immature gametocytes - sexual stage precursor cells - likewise disappear from circulation. Recent work has demonstrated that these sexual stage parasites are located in the hematopoietic system of the bone marrow before mature gametocytes are released into the bloodstream to facilitate mosquito transmission. However, as sequestration occurs only in vivo and not during in vitro culture, the mechanisms by which it is regulated and enacted (particularly by the gametocyte stage) remain poorly understood. RESULTS We generated the most comprehensive P. falciparum functional gene network to date by integrating global transcriptional data from a large set of asexual and sexual in vitro samples, patient-derived in vivo samples, and a new set of in vitro samples profiling sexual commitment. We defined more than 250 functional modules (clusters) of genes that are co-expressed primarily during the intra-erythrocytic parasite cycle, including 35 during sexual commitment and gametocyte development. Comparing the in vivo and in vitro datasets allowed us, for the first time, to map the time point of asexual parasite sequestration in patients to 22 hours post-invasion, confirming previous in vitro observations on the dynamics of host cell modification and cytoadherence. Moreover, we were able to define the properties of gametocyte sequestration, demonstrating the presence of two circulating gametocyte populations: gametocyte rings between 0 and approximately 30 hours post-invasion and mature gametocytes after around 7 days post-invasion. CONCLUSIONS This study provides a bioinformatics resource for the functional elucidation of parasite life cycle dynamics and specifically demonstrates the presence of the gametocyte ring stages in circulation, adding significantly to our understanding of the dynamics of gametocyte sequestration in vivo.
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Affiliation(s)
- Karell G Pelle
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA 02115 USA
| | - Keunyoung Oh
- Department of Biostatistics, Harvard School of Public Health, Boston, MA 02115 USA
| | - Kathrin Buchholz
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA 02115 USA
| | - Vagheesh Narasimhan
- Department of Biostatistics, Harvard School of Public Health, Boston, MA 02115 USA
| | - Regina Joice
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA 02115 USA
| | - Danny A Milner
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA 02115 USA ; Department of Pathology, Brigham and Women's Hospital, Boston, MA 02115 USA
| | - Nicolas Mb Brancucci
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA 02115 USA ; Swiss Tropical and Public Health Institute, 4051 Basel, Switzerland
| | - Siyuan Ma
- Department of Biostatistics, Harvard School of Public Health, Boston, MA 02115 USA
| | - Till S Voss
- Swiss Tropical and Public Health Institute, 4051 Basel, Switzerland
| | - Ken Ketman
- Program in Cellular and Molecular Medicine, Children's Hospital, Boston, MA 02115 USA
| | - Karl B Seydel
- College of Osteopathic Medicine, Michigan State University, East Lansing, MI 48825 USA ; Blantyre Malaria Project, University of Malawi College of Medicine, Blantyre, 3 Malawi
| | - Terrie E Taylor
- College of Osteopathic Medicine, Michigan State University, East Lansing, MI 48825 USA ; Blantyre Malaria Project, University of Malawi College of Medicine, Blantyre, 3 Malawi
| | - Natasha S Barteneva
- Program in Cellular and Molecular Medicine, Children's Hospital, Boston, MA 02115 USA ; Department of Pediatrics, Harvard Medical School, Boston, MA 02115 USA
| | - Curtis Huttenhower
- Department of Biostatistics, Harvard School of Public Health, Boston, MA 02115 USA ; The Broad Institute of Harvard and MIT, Cambridge, MA 02142 USA
| | - Matthias Marti
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA 02115 USA
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Abstract
Leucrose formation from sucrose and fructose by dextransucrase is of practical interest. It has been investigated at different experimental conditions, including the influence of temperature on reaction rate and selectivity. Under appropriate conditions high product yield can be obtained. Furthermore, a model is presented that allows interpretation of the experimental data.
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Affiliation(s)
- M Böker
- Sugar Institute, Institut für Technologie der Kohlenhydrate at the Technical University of Braunschweig, Langer Kamp 5, D-38106 Braunschweig, Germany
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Vorobjev IA, Buchholz K, Prabhat P, Ketman K, Egan ES, Marti M, Duraisingh MT, Barteneva NS. Optimization of flow cytometric detection and cell sorting of transgenic Plasmodium parasites using interchangeable optical filters. Malar J 2012; 11:312. [PMID: 22950515 PMCID: PMC3544587 DOI: 10.1186/1475-2875-11-312] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2012] [Accepted: 08/29/2012] [Indexed: 12/05/2022] Open
Abstract
Background Malaria remains a major cause of morbidity and mortality worldwide. Flow cytometry-based assays that take advantage of fluorescent protein (FP)-expressing malaria parasites have proven to be valuable tools for quantification and sorting of specific subpopulations of parasite-infected red blood cells. However, identification of rare subpopulations of parasites using green fluorescent protein (GFP) labelling is complicated by autofluorescence (AF) of red blood cells and low signal from transgenic parasites. It has been suggested that cell sorting yield could be improved by using filters that precisely match the emission spectrum of GFP. Methods Detection of transgenic Plasmodium falciparum parasites expressing either tdTomato or GFP was performed using a flow cytometer with interchangeable optical filters. Parasitaemia was evaluated using different optical filters and, after optimization of optics, the GFP-expressing parasites were sorted and analysed by microscopy after cytospin preparation and by imaging cytometry. Results A new approach to evaluate filter performance in flow cytometry using two-dimensional dot blot was developed. By selecting optical filters with narrow bandpass (BP) and maximum position of filter emission close to GFP maximum emission in the FL1 channel (510/20, 512/20 and 517/20; dichroics 502LP and 466LP), AF was markedly decreased and signal-background improve dramatically. Sorting of GFP-expressing parasite populations in infected red blood cells at 90 or 95% purity with these filters resulted in 50-150% increased yield when compared to the standard filter set-up. The purity of the sorted population was confirmed using imaging cytometry and microscopy of cytospin preparations of sorted red blood cells infected with transgenic malaria parasites. Discussion Filter optimization is particularly important for applications where the FP signal and percentage of positive events are relatively low, such as analysis of parasite-infected samples with in the intention of gene-expression profiling and analysis. The approach outlined here results in substantially improved yield of GFP-expressing parasites, and requires decreased sorting time in comparison to standard methods. It is anticipated that this protocol will be useful for a wide range of applications involving rare events.
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Affiliation(s)
- Ivan A Vorobjev
- Immune Disease Institute and Program in Cellular and Molecular Medicine, Children's Hospital, D-239, 200 Longwood Avenue, 02115, Boston, MA, USA
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da Cruz FP, Martin C, Buchholz K, Lafuente-Monasterio MJ, Rodrigues T, Sönnichsen B, Moreira R, Gamo FJ, Marti M, Mota MM, Hannus M, Prudêncio M. Drug screen targeted at Plasmodium liver stages identifies a potent multistage antimalarial drug. J Infect Dis 2012; 205:1278-86. [PMID: 22396598 PMCID: PMC3308910 DOI: 10.1093/infdis/jis184] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Plasmodium parasites undergo a clinically silent and obligatory developmental phase in the host's liver cells before they are able to infect erythrocytes and cause malaria symptoms. To overcome the scarcity of compounds targeting the liver stage of malaria, we screened a library of 1037 existing drugs for their ability to inhibit Plasmodium hepatic development. Decoquinate emerged as the strongest inhibitor of Plasmodium liver stages, both in vitro and in vivo. Furthermore, decoquinate kills the parasite's replicative blood stages and is active against developing gametocytes, the forms responsible for transmission. The drug acts by selectively and specifically inhibiting the parasite's mitochondrial bc(1) complex, with little cross-resistance with the antimalarial drug atovaquone. Oral administration of a single dose of decoquinate effectively prevents the appearance of disease, warranting its exploitation as a potent antimalarial compound.
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Affiliation(s)
- Filipa P da Cruz
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Portugal
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Buchholz K, Burke TA, Williamson KC, Wiegand RC, Wirth DF, Marti M. A high-throughput screen targeting malaria transmission stages opens new avenues for drug development. J Infect Dis 2011; 203:1445-53. [PMID: 21502082 PMCID: PMC3080890 DOI: 10.1093/infdis/jir037] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A major goal of the worldwide malaria eradication program is the reduction and eventual elimination of malaria transmission. All currently available antimalarial compounds were discovered on the basis of their activity against the asexually reproducing red blood cell stages of the parasite, which are responsible for the morbidity and mortality of human malaria. Resistance against these compounds is widespread, and there is an urgent need for novel approaches to reduce the emergence of resistance to new antimalarials as they are introduced. We have established and validated the first high-throughput assay targeting the red blood cell parasite stage required for transmission, the sexually reproducing gametocyte. This assay will permit identification of compounds specifically targeting the transmission stages in addition to the asexual stage parasites. Such stage-specific compounds may be used in a combination therapy, reducing the emergence of resistance by blocking transmission of resistant parasites that may be selected in a patient.
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Affiliation(s)
- Kathrin Buchholz
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA 02115, USA
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Buchholz K, Gebert A, Mummert K, Eckert J, Schultz L. Investigations on the Electrochemical Behavior of Zr-Al-Cu-Ni Bulk Metallic Glass. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-554-161] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
AbstractThe passivation behavior of bulk glassy Zr55Al10Cu30Ni5 alloy samples in weakly alkaline sulphate solution (pH = 8) is investigated in comparison to the arc-melted crystalline alloy, to the main alloying component zirconium and to aluminium. Results of potentiodynamic and potentiostatic polarization measurements reveal the formation of a stable passivating surface film on the glassy alloy grown by a high-field mechanism. Auger electron spectroscopic investigations of anodized sample surfaces show that the films formed on the glassy Zr-Al-Cu-Ni alloys exhibit a composition gradient in cross-sectional direction. In 0.001M NaCl electrolytes bulk glassy Zr-Al- Cu-Ni samples are susceptible to pitting corrosion, which is due to the existence of crystalline inclusions.
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Buchholz K, Putrianti ED, Rahlfs S, Schirmer RH, Becker K, Matuschewski K. Molecular genetics evidence for the in vivo roles of the two major NADPH-dependent disulfide reductases in the malaria parasite. J Biol Chem 2010; 285:37388-95. [PMID: 20852334 PMCID: PMC2988344 DOI: 10.1074/jbc.m110.123323] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2010] [Revised: 08/27/2010] [Indexed: 11/06/2022] Open
Abstract
Malaria-associated pathology is caused by the continuous expansion of Plasmodium parasites inside host erythrocytes. To maintain a reducing intracellular milieu in an oxygen-rich environment, malaria parasites have evolved a complex antioxidative network based on two central electron donors, glutathione and thioredoxin. Here, we dissected the in vivo roles of both redox pathways by gene targeting of the respective NADPH-dependent disulfide reductases. We show that Plasmodium berghei glutathione reductase and thioredoxin reductase are dispensable for proliferation of the pathogenic blood stages. Intriguingly, glutathione reductase is vital for extracellular parasite development inside the insect vector, whereas thioredoxin reductase is dispensable during the entire parasite life cycle. Our findings suggest that glutathione reductase is the central player of the parasite redox network, whereas thioredoxin reductase fulfils a specialized and dispensable role for P. berghei. These results also indicate redundant roles of the Plasmodium redox pathways during the pathogenic blood phase and query their suitability as promising drug targets for antimalarial intervention strategies.
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Affiliation(s)
- Kathrin Buchholz
- From the Interdisciplinary Research Centre, Justus-Liebig University, Giessen 35390, Germany
- the Biochemistry Centre, Ruprecht-Karls University, Heidelberg 69120, Germany
- the Department of Parasitology, Heidelberg University School of Medicine, Heidelberg 69120, Germany, and
| | - Elyzana D. Putrianti
- the Parasitology Unit, Max Planck Institute for Infection Biology, Berlin 10117, Germany
| | - Stefan Rahlfs
- From the Interdisciplinary Research Centre, Justus-Liebig University, Giessen 35390, Germany
| | - R. Heiner Schirmer
- the Biochemistry Centre, Ruprecht-Karls University, Heidelberg 69120, Germany
| | - Katja Becker
- From the Interdisciplinary Research Centre, Justus-Liebig University, Giessen 35390, Germany
| | - Kai Matuschewski
- the Parasitology Unit, Max Planck Institute for Infection Biology, Berlin 10117, Germany
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Daum B, Buchholz K. High Yield and High Selectivity of Reactions in the Frozen State--the Acceptor Reaction of Dextransucrase. BIOCATAL BIOTRANSFOR 2009. [DOI: 10.1080/10242420210156] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Neubauer A, Walter M, Buchholz K. Formation of Inulobiose from Difructoseanhydride III Catalysed by a Lysate fromArthrobacter UreafaciensATCC 21124. BIOCATAL BIOTRANSFOR 2009. [DOI: 10.3109/10242420009015262] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Kralj S, Buchholz K, Dijkhuizen L, Seibel J. Fructansucrase enzymes and sucrose analogues: A new approach for the synthesis of unique fructo-oligosaccharides. BIOCATAL BIOTRANSFOR 2009. [DOI: 10.1080/10242420701789478] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Tzanetos D, Buchholz K, Fahrenholz J. Is Levocetirizine Less Sedating than Cetirizine? J Allergy Clin Immunol 2009. [DOI: 10.1016/j.jaci.2008.12.500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Buchholz K, Tinazli A, Kleefen A, Dorfner D, Pedone D, Rant U, Tampé R, Abstreiter G, Tornow M. Silicon-on-insulator based nanopore cavity arrays for lipid membrane investigation. Nanotechnology 2008; 19:445305. [PMID: 21832728 DOI: 10.1088/0957-4484/19/44/445305] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We present the fabrication and characterization of nanopore microcavities for the investigation of transport processes in suspended lipid membranes. The cavities are situated below the surface of silicon-on-insulator (SOI) substrates. Single cavities and large area arrays were prepared using high resolution electron-beam lithography in combination with reactive ion etching (RIE) and wet chemical sacrificial underetching. The locally separated compartments have a circular shape and allow the enclosure of picoliter volume aqueous solutions. They are sealed at their top by a 250 nm thin Si membrane featuring pores with diameters from 2 µm down to 220 nm. The Si surface exhibits excellent smoothness and homogeneity as verified by AFM analysis. As biophysical test system we deposited lipid membranes by vesicle fusion, and demonstrated their fluid-like properties by fluorescence recovery after photobleaching. As clearly indicated by AFM measurements in aqueous buffer solution, intact lipid membranes successfully spanned the pores. The nanopore cavity arrays have potential applications in diagnostics and pharmaceutical research on transmembrane proteins.
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Affiliation(s)
- K Buchholz
- Walter-Schottky-Institute, TU Munich, Am Coulombwall, 85748 Garching, Germany
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Buchholz K, Seibel J. Industrial carbohydrate biotransformations. Carbohydr Res 2008; 343:1966-79. [DOI: 10.1016/j.carres.2008.02.007] [Citation(s) in RCA: 115] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2007] [Revised: 02/04/2008] [Accepted: 02/06/2008] [Indexed: 11/16/2022]
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Buchholz K, Rahlfs S, Schirmer RH, Becker K, Matuschewski K. Depletion of Plasmodium berghei plasmoredoxin reveals a non-essential role for life cycle progression of the malaria parasite. PLoS One 2008; 3:e2474. [PMID: 18575607 PMCID: PMC2429964 DOI: 10.1371/journal.pone.0002474] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2008] [Accepted: 04/30/2008] [Indexed: 11/18/2022] Open
Abstract
Proliferation of the pathogenic Plasmodium asexual blood stages in host erythrocytes requires an exquisite capacity to protect the malaria parasite against oxidative stress. This function is achieved by a complex antioxidant defence system composed of redox-active proteins and low MW antioxidants. Here, we disrupted the P. berghei plasmoredoxin gene that encodes a parasite-specific 22 kDa member of the thioredoxin superfamily. The successful generation of plasmoredoxin knockout mutants in the rodent model malaria parasite and phenotypic analysis during life cycle progression revealed a non-vital role in vivo. Our findings suggest that plasmoredoxin fulfils a specialized and dispensable role for Plasmodium and highlights the need for target validation to inform drug development strategies.
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Affiliation(s)
- Kathrin Buchholz
- Interdisciplinary Research Centre, Justus-Liebig University, Giessen, Germany
- Biochemistry Centre, Ruprecht-Karls University, Heidelberg, Germany
- Department of Parasitology, School of Medicine, Heidelberg University, Heidelberg, Germany
| | - Stefan Rahlfs
- Interdisciplinary Research Centre, Justus-Liebig University, Giessen, Germany
| | | | - Katja Becker
- Interdisciplinary Research Centre, Justus-Liebig University, Giessen, Germany
- * E-mail: (KB); (KM)
| | - Kai Matuschewski
- Department of Parasitology, School of Medicine, Heidelberg University, Heidelberg, Germany
- * E-mail: (KB); (KM)
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Jördening HJ, Erhardt F, Holtkamp M, Buchholz K, Scholl S. Verfahrens- und Katalysatordesign als Aufarbeitungsstrategie für die enzymatische Darstellung von Isomaltose. CHEM-ING-TECH 2008. [DOI: 10.1002/cite.200800033] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Schütze M, Kundt G, Buchholz K, Piek J. [Which factors are predictive for long-term complaints after mild traumatic brain injuries?]. Versicherungsmedizin 2008; 60:78-83. [PMID: 18595643] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Each year 330 of every 100,000 inhabitants in Germany suffer a mild traumatic brain injury. About 25% suffer persisting post-concussion syndrome (headache, dizziness). Although many studies have been carried out to make a prognosis of the long-term outcome of these patients, there are still no relevant tests for a valuable statement. The aim of our study was to identify parameters to predict post-traumatic complaints. Therefore we conducted a prospective study of 74 patients who were admitted with a mild traumatic brain injury in our hospital from March 2004 till October 2006. We were able to show a significant correlation between complaints and a pathological CT-scan and biochemical markers during the first two weeks. For long-term complaints only the SKT (Syndromkurztest) we used for a neuropsychological assesment was able to show a significant correlation.
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Affiliation(s)
- M Schütze
- Abteilung für Neurochirurgie, Chirurgische Universitätsklinik Rostock
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Abstract
Image transfer by mobile phones with built-in cameras (1 Megapixel CCD digital camera, 7 stage digital zoom, max. picture size 858 x 1 144 pixels, display resolution 240 x 320 dots, 262 K colour system CGS LCD) was introduced into clinical practice in the author's department in July 2004 to improve communication between neurosurgeons. During the first 12 months of use 13-72 images per month with an average of 1.4 images/case were transmitted via the regular German mobile phone net (GRPS standard, 40 KBit/s) among all neurosurgeons. Most images were transferred from the resident on call to the senior neurosurgeon backing him up. Overall, the system was extremely reliable, quick, and enabled immediate decisions in all emergency situations. In conclusion, image transfer by mobile phones has significantly improved communication within our department.
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Affiliation(s)
- J Piek
- Abteilung für Neurochirurgie, Chirurgische Universitätsklinik Rostock, Rostock, Germany.
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Erhardt FA, Herrmann M, Jördening HJ, Scholl S, Buchholz K. Integrierte Synthese und Trennung von Isomaltose in einem bi-enzymatischen Mehrphasenreaktor. CHEM-ING-TECH 2006. [DOI: 10.1002/cite.200650233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Akoachere M, Buchholz K, Fischer E, Burhenne J, Haefeli WE, Schirmer RH, Becker K. In vitro assessment of methylene blue on chloroquine-sensitive and -resistant Plasmodium falciparum strains reveals synergistic action with artemisinins. Antimicrob Agents Chemother 2006; 49:4592-7. [PMID: 16251300 PMCID: PMC1280165 DOI: 10.1128/aac.49.11.4592-4597.2005] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Methylene blue (MB) represents a promising antimalarial drug candidate for combination therapies against drug-resistant parasite strains. To support and facilitate the application of MB in future field trials, we studied its antiparasitic effects in vitro. MB is active against all blood stages of both chloroquine (CQ)-sensitive and CQ-resistant P. falciparum strains with 50% inhibitory concentration (IC50) values in the lower nanomolar range. Ring stages showed the highest susceptibility. As demonstrated by high-performance liquid chromatography-tandem mass spectrometry on different cell culture compartments, MB is accumulated in malarial parasites. In drug combination assays, MB was found to be antagonistic with CQ and other quinoline antimalarials like piperaquine and amodiaquine; with mefloquine and quinine, MB showed additive effects. In contrast, we observed synergistic effects of MB with artemisinin, artesunate, and artemether for all tested parasite strains. Artemisinin/MB combination concentration ratios of 3:1 were found to be advantageous, demonstrating that the combination of artemisinin with a smaller amount of MB can be recommended for reaching maximal therapeutic effects. Our in vitro data indicate that combinations of MB with artemisinin and related endoperoxides might be a promising option for treating drug-resistant malaria and should be studied in future field trials. Resistance development under this drug combination is unlikely to occur.
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Affiliation(s)
- Monique Akoachere
- Interdisciplinary Research Centre, Justus-Liebig-University, Heinrich-Buff-Ring 26-32, 35392 Giessen, Germany
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Abstract
The anaerobic degradation of the polyesters poly-3-hydroxybutyrate (PHB) and poly-3-hydroxybutyrate-co-3-hydroxyvalerate (PHBV) was investigated with special regard to intermediate products, kinetics, and yields. During the degradation of PHBV acetate, propionate, n-butyrate, and n-valerate were detected. Additionally, 3-hydroxybutyrate and 3-hydroxyvalerate and four dimeric esters of these two molecules were identified by GC-MS measurements. Three different test systems for the anaerobic degradation of polyesters were studied. It was not possible to get reproducible results by means of the Anaerobic Sturm-test, a simple system based on carbon dioxide measurement. Secondly, a system based on the GC measurement of accumulated organic acids was investigated. A degradation of 90% in two days was calculated by a carbon balance. Best results were reached with the third test system based on the measurement of methane with a gas meter. A degradation of 99% was observed within 30 days.
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Affiliation(s)
- A Reischwitz
- Sugar Institute, Institut für Technologie der Kohlenhydrate, Technical University of Braunschweig, Braunschweig, Germany
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Baciu IE, Jördening HJ, Seibel J, Buchholz K. Investigations of the transfructosylation reaction by fructosyltransferase from B. subtilis NCIMB 11871 for the synthesis of the sucrose analogue galactosyl-fructoside. J Biotechnol 2005; 116:347-57. [PMID: 15748761 DOI: 10.1016/j.jbiotec.2004.10.019] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2004] [Revised: 10/04/2004] [Accepted: 10/14/2004] [Indexed: 10/25/2022]
Abstract
The exo-fructosyltransferase produced from B. subtilis NCIMB 11871 strain transfers the fructose moiety from donor alpha12 linked saccharides such as sucrose, raffinose and stachyose to the acceptor d-galactose, leading to the sucrose analogue, galactosyl-fructoside. Here, we report detailed kinetic studies. The enzyme showed a remarkably high optimal temperature at 50 degrees C and was effectively immobilised on Eupergit C 250 L and Trisopor-Amino. This is also the first report about the equilibrium of the transfructosylation reaction, its activation energy determination, the structure of the product and its preparative scale isolation.
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Affiliation(s)
- I-E Baciu
- Technical Chemistry, Department for Carbohydrate Technology, Technical University Braunschweig, Langer Kamp 5, D-38106 Braunschweig, Germany
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Berensmeier S, Ergezinger M, Bohnet M, Buchholz K. Design of immobilised dextransucrase for fluidised bed application. J Biotechnol 2004; 114:255-67. [PMID: 15522435 DOI: 10.1016/j.jbiotec.2004.04.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2003] [Revised: 04/19/2004] [Accepted: 04/22/2004] [Indexed: 10/26/2022]
Abstract
Immobilisation of dextransucrase from Leuconostoc mesenteroides NRRL B-512F in alginate is optimised for applications in a fluidised bed reactor with high concentrated sugar solutions, in order to allow a continuous formation of defined oligosaccharides as prebiotic isomalto-oligosaccharides. Efficient design of fluidised bed immobilised biocatalyst in high density solutions requires particles with elevated density, high effectiveness and both thermal and mechanical stability. Inert silica flour/sand (Mikrosil 300) as supplement turned out to be best suited for increasing the density up to 1400 kg m(-3) of the alginate beads and generating a stable expanded bed without diffusional restrictions. Kinetic investigations demonstrate that low effectiveness of immobilised enzyme due to close association to dextranpolymers (dextran content of enzyme preparation >90%) is compensated by reducing the particle size and/or by decreasing the dextran content. A low dextran content (5%) is sufficient to immobilise and stabilise the enzyme, thus diffusional limitation is reduced essentially while operational stability is maintained. Fluidisation behaviour and bed expansion proved to be appropriate for the intended application. Both calculated and measured expansion coefficients showed good agreement for different conditions.
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Affiliation(s)
- S Berensmeier
- Department for Carbohydrates, Technical University Braunschweig, Langer Kamp 5, D-38106 Braunschweig, Germany
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Berensmeier S, Buchholz K. Separation of isomaltose from high sugar concentrated enzyme reaction mixture by dealuminated β-zeolite. Sep Purif Technol 2004. [DOI: 10.1016/j.seppur.2003.10.012] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Berensmeier S, Singh SA, Meens J, Buchholz K. Cloning of the pelA gene from Bacillus licheniformis 14A and biochemical characterization of recombinant, thermostable, high-alkaline pectate lyase. Appl Microbiol Biotechnol 2003; 64:560-7. [PMID: 14673544 DOI: 10.1007/s00253-003-1446-9] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2003] [Revised: 08/11/2003] [Accepted: 09/07/2003] [Indexed: 10/26/2022]
Abstract
The pectate lyase gene pelA from alkaliphilic Bacillus licheniformis strain 14A was cloned and sequenced. The nucleotide sequence corresponded to an open reading frame of 1,026 bp that codes for a 39 amino acid signal peptide and a mature protein with a molecular mass of 33,451 Da. The mature PelA showed significant homology to other pectate lyases belonging to polysaccharide lyase family 1, such as enzymes from different Bacillus spp. and Erwinia chrysanthemi. The pelA gene was expressed in Escherichia coli as a recombinant fusion protein containing a C-terminal His-tag, allowing purification to near homogeneity in a one-step procedure. The values for the kinetic parameters K(m) and Vmax of the fusion protein were 0.56 g/l and 51 micromol/min, respectively. The activity of purified PelAHis was inhibited in the presence of excess substrate. Characterization of product formation revealed unsaturated trigalacturonate as the main product. The yields of unsaturated trigalacturonic acids were further examined for the substrates polygalacturonic acid, citrus pectin and sugar-beet pectin.
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Affiliation(s)
- S Berensmeier
- Department for Carbohydrates, Technical University Braunschweig, Langer Kamp 5, 38106 Braunschweig, Germany
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Abstract
Fluidized bed adsorption can substantially simplify the recovery of products from fermentation. There are, however, several critical parameters, which have a significant influence on the performance of such systems. This paper presents experimental results on the adsorption of an antibiotic, Cephalosporin C, on macroporous adsorbents of the polystyrene type and on an ion exchanger. Internals (static mixers) were used to control bed expansion and mixing, the range of flow rates could thus be extended significantly. An integrated mathematical model was developed comprising bed expansion, residence time distribution and mixing, adsorption kinetics and equilibria.
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Abstract
Salt-sensitive normotensive men exhibit an enhanced pressor response to mental stress. Although an enhanced pressor response is associated with higher affective startle modulation in men, an association between salt sensitivity of blood pressure and affective startle modulation has not been studied so far. We studied reactivity to mental stress and startle modulation in 14 salt-sensitive healthy white male students and 14 salt-resistant control subjects, who were well matched for age, body mass index, physical fitness, and family history of hypertension. Subjects performed a computerized information-processing task under time pressure (manometer test), while heart rate and blood pressure were continuously registered. In a separate session, subjects viewed a series of 42 pictures of the International Affective Picture System (IAPS), varying in pleasure and arousal, while acoustic startle probes were administered randomly, and electromyogram activity of the orbicular eye muscle was continuously recorded. Startle modulation was calculated as the difference between startle responses under negative and positive affective stimuli. In contrast to salt-resistant subjects, salt-sensitive subjects showed significantly enhanced startle amplitudes under negative stimuli and diminished amplitudes under positive stimuli. Thus, salt-sensitive subjects displayed a significantly higher startle modulation than did salt-resistant subjects (P<0.05). Subjective ratings of the presented IAPS pictures did not differ between the groups. The increased startle modulation of salt-sensitive subjects suggests an enhanced activity of the central nucleus of the amygdala. This enhanced central nervous responsiveness may contribute to higher sympathetic pressor reactivity and, thus, to the later development of hypertension in salt-sensitive individuals.
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Affiliation(s)
- K Buchholz
- Division of Psychosomatic Medicine, Benjamin Franklin Medical Center, Freie Universität Berlin, Berlin, Germany
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Deter HC, Buchholz K, Schorr U, Mathiak K, Sharma AM. Salt-sensitivity and other predictors of stress-related cardiovascular reactivity in healthy young males. Clin Exp Hypertens 2001; 23:213-25. [PMID: 11339688 DOI: 10.1081/ceh-100102661] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Individuals whose mean arterial blood pressure is depending on oral salt intake are considered salt-sensitive and are at risk of developing essential hypertension. This study investigates the role of salt-sensitivity with respect to systolic blood pressure reactions under standardized mental stress. Forty-three healthy young males, previously characterized as salt-sensitive (n=16) or salt-resistant (n=27) by a dietary regimen, were subjected to multimodal physiological measurement during a computerized stress test and underwent comprehensive psychometrical testing. The most important predictors for systolic blood pressure reactions to stress were the degree of salt-sensitivity, body mass index and psychological characteristics like anxiety. The highest correlations with the degree of salt-sensitivity were found for the parameters age, systolic blood pressure reaction under stress, high frequency band of heart rate variability and two psychological variables. The concept of salt-sensitivity is a novel biological component that might contribute to reactivity research in subjects at high risk for essential hypertension.
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Affiliation(s)
- H C Deter
- Department of Psychosomatic Medicine and Psychotherapy, Benjamin Franklin Hospital, Free University of Berlin, Germany
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Schaumann R, Fingerle V, Buchholz K, Spencker FB, Rodloff AC. Facial palsy caused by Borrelia infection in a twin pregnancy in an area of nonendemicity. Clin Infect Dis 1999; 29:955-6. [PMID: 10589933 DOI: 10.1086/520481] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Affiliation(s)
- R Schaumann
- Institute for Medical Microbiology, University Leipzig, Germany.
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Buchholz K, Schorr U, Turan S, Sharma AM, Deter HC. [Emotional irritability and anxiety in salt-sensitive persons at risk for essential hypertension]. Psychother Psychosom Med Psychol 1999; 49:284-9. [PMID: 10488649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Abstract
Personality traits such as anxiety and anger have long been associated with essential hypertension. However, the results of past studies have been criticised for selection bias, and it has not been clarified whether psychological traits are causes or consequences of high blood pressure. We studied emotional state and trait patterns and reactivity to mental stress in 16 healthy salt-sensitive volunteers at genetic risk of developing hypertension, and a well-matched control group. We have previously reported increased blood pressure reactivity to mental stress in those individuals. In this paper, we present the results of several standardized psychological questionnaires in which salt-sensitive individuals displayed increased anxiety (p < 0.01), emotional irritation (p < 0.01) and a lower level of anger control (p < 0.01). Thus, an elevated level of anxiety and irritation, as well as an increased blood-pressure response to mental stress may play a role in the development of salt-sensitive hypertension.
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Affiliation(s)
- K Buchholz
- Klinik für Psychotherapie, Psychosomatik und Allgemeinmedizin, Universitätsklinikum Benjamin Franklin, FU Berlin
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Dols M, Remaud-Simeon M, Willemot RM, Demuth B, Jordening HJ, Buchholz K, Monsan P. Kinetic modeling of oligosaccharide synthesis catalyzed by leuconostoc mesenteroides NRRL B-1299 dextransucrase. Biotechnol Bioeng 1999; 63:308-15. [PMID: 10099610 DOI: 10.1002/(sici)1097-0290(19990505)63:3<308::aid-bit7>3.0.co;2-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The kinetic behavior of soluble and insoluble forms of dextransucrase from Leuconostoc mesenteroides NRRL B-1299 was investigated with sucrose as substrate and maltose as acceptor. To study the parameters involved, a kinetic model was applied that was previously developed for L. mesenteroides NRRL B-512F dextransucrase. There are significant correlations between the parameters of the soluble form of B-1299 dextransucrase and those calculated for the B-512F enzyme; that is, their properties are comparable and differ from those of the insoluble form of B-1299 dextransucrase. Whereas the calculated parameters for high maltose concentrations describe the kinetic behavior very well, the time curves for low maltose concentrations were not described correctly. Therefore, the parameters were calculated separately for the two ranges. Copyright 1999 John Wiley & Sons, Inc.
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Affiliation(s)
- M Dols
- Laboratoire de Biotechnologie-Bioprocedes, UMR 5504 INSA/CNRS and Laboratoire Associe INRA, INSA, Complexe scientifique de Rangueil, 31 077 Toulouse cedex 4, France
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Abstract
Dextransucrase catalyses the formation of dextran, but also of numerous oligosaccharides from sucrose and different acceptors, if appropriate conditions are chosen. Much experimental work has been carried out and a scheme of reactions and a mathematical model have been developed to describe the complex kinetic behaviour of the enzyme. A computer program was used to calculate the parameters of the model from a broad range of experimental data, investigating a large number of kinetic tests with the acceptors maltose and fructose. The results lead to design considerations for a continuous reactor system with immobilized dextransucrase to produce leucrose, a disaccharide of industrial interest.
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Affiliation(s)
- B Demuth
- Lehrstuhl für Technologie der Kohlenhydrate, Technical University of Braunschweig, Langer Kamp 5, D-38106 Braunschweig, Germany
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Affiliation(s)
- K Heincke
- Technical University, Braunschweig, Germany
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Affiliation(s)
- B Daum
- Carbohydrate Technology, Technical University, D-38106 Braunschweig, Germany
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Müller M, Bohnet M, Marschall A, Näveke R, Taddigs T, Buchholz K. Einsatz von Hydrozyklonen zur Fraktionierung und Konzentrierung von Biomasse. CHEM-ING-TECH 1997. [DOI: 10.1002/cite.3306909127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Abstract
OBJECTIVE To evaluate the psychophysiological response to mental stress of young healthy salt-sensitive normotensive subjects. METHODS Thirty-two healthy volunteers who had previously been phenotyped for salt sensitivity were selected for the study. The 16 salt-sensitive and 16 salt-resistant subjects, who were matched for age, body mass index and family history of hypertension, underwent a mental stress test consisting of an information-processing task performed under time pressure (the Manometer test). During the experimental session the blood pressure, heart rate and pulse-wave velocity were registered continuously. Before and after the mental task subjects were instructed to complete several standardized psychological state and trait questionnaires. RESULTS Mental stress resulted in a greater rise in blood pressure (P < 0.05) and in pulse-wave velocity (P < 0.01) in salt-sensitive than in salt-resistant individuals. Salt-sensitive subjects also displayed significantly higher levels of anxiety (P < 0.01) and a lower level of control of anger (P < 0.01) than did salt-resistant subjects. Furthermore, the level of irritation of the salt-sensitive subjects was higher both before (P < 0.01) and after (P < 0.05) the stress test CONCLUSIONS An increased responsiveness of the blood pressure to mental stress and an increased level of irritation are associated with salt sensitivity in normotensive subjects. These findings are in line with the hypothesis that psychophysiological traits play a role in the development of salt-sensitive hypertension.
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Affiliation(s)
- H C Deter
- Department of Internal Medicine, Universitätsklinikum Benjamin Franklin, Free University of Berlin, Germany
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Stoppok E, Walter J, Buchholz K. The effect of pH and oxygen concentration on the formation of 3-ketodisaccharides by Agrobacterium tumefaciens. Appl Microbiol Biotechnol 1995; 43:706-12. [PMID: 7546608 DOI: 10.1007/bf00164777] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The further optimization of 3-ketodisaccharide formation with sucrose, leucrose and iso maltulose was studied with special regard to pH and oxygen concentration in the reaction mixture with resting cells of Agrobacterium tumefaciens. It was found that the optimal pH values for the highest reaction rate and highest yield were different as the pH affected the stability of the 3-keto derivatives formed. A pH shift to 5.0 clearly reduced the enzymatic degradation of the 3-keto derivatives thus stabilizing them. The influence of constant oxygen concentrations on 3-ketosucrose formation was tested showing results not explicable with normal Michaelis-Menten kinetics. For each substrate a maximum of reaction rate and yield were obtained at very low oxygen concentrations.
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Affiliation(s)
- E Stoppok
- Institut für Technologie der Kohlenhydrate an der TU Braunschweig-Zuckerinstitut, Germany
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45
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Stoppok E, Walter J, Buchholz K. The effect of pH and oxygen concentration on the formationof 3-ketodisaccharides by Agrobacterium tumefaciens. Appl Microbiol Biotechnol 1995. [DOI: 10.1007/s002530050474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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46
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Fischer H, Helmrich P, Nitzgen B, Buchholz K, Hadding U. Astrocyted infected by Toxoplasma gondii express and release IL1 and IL6. J Neuroimmunol 1994. [DOI: 10.1016/0165-5728(94)90300-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Girlich D, Lüdemann HD, Buttersack C, Buchholz K. c , T-Dependence of the Self Diffusion in Concentrated Aqueous Sucrose Solutions. ACTA ACUST UNITED AC 1994. [DOI: 10.1515/znc-1994-3-415] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The self diffusion coefficients D of the water molecules and of sucrose have been determined by the pulsed field gradient NMR technique over a wide range of temperatures and concentrations (cmax: 70% w/w suc.). All temperature dependencies can be fitted to a Vogel- Tammann-Fulcher equation. The isothermic concentration dependence of D for the sucrose is given by a simple exponential concentration dependence
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Abstract
3-Ketosucrose (alpha-D-ribo-hexopyranosyl-3-ulose-beta-D-fructofuranoside), obtained from sucrose via microbial oxidation with Agrobacterium tumefaciens, was shown to be an appropriate and versatile synthon for regioselective syntheses. Condensation with hydroxylamine and its derivatives with allyl and benzyl groups leads to the oxime and the corresponding substituted products. By reductive amination 3-amino-3-deoxy-alpha-D-allopyranosyl-beta-D-fructofuranoside is obtained which can readily be submitted to further functionalization to methacryloyl and fatty acid derivatives. After silylation of 3-ketosucrose the 3-allyl and butylene-substituted as well as decyl- and dodecyl-substituted sucrose can be obtained via Grignard reaction, the side chains being C-C linked to the saccharide.
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Affiliation(s)
- M Pietsch
- Institut für Technologie der Kohlenhydrate an der Technischen Universität Braunschweig-Sugar Institute, Germany
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49
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Abstract
Investigations on the microbial modification of sucrose to the corresponding 3-keto-derivative were carried out with resting cells of Agrobacterium tumefaciens NCPPB 396. This highly specific oxidation to yield the 3-keto-derivative has been analysed kinetically with varying substrate and cell mass concentrations. The formation of the corresponding 3-keto-derivative depended strongly on the reaction time and the aeration rate and was maximal at aeration rates up to 11.5 volume air/cultivation volume per minute with resting cells. The product formation increased with increasing substrate concentrations. However, the product yield was maximal at substrate concentrations below 20 g/l. Data pertaining to the production of active cell mass as well as for maximal 3-keto-derivative formation are presented in this paper. Also included are some applications for these derivatives.
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Affiliation(s)
- E Stoppok
- Institut fur landwirtschaftliche Technologie und Zuckerindustrie an der TU Braunschweig, Langer Kamp 5, Germany
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