Publications by authors named "Broda E"

Sophisticated drug delivery systems are coated with targeting ligands to improve the specific adhesion to surface receptors on diseased cells. In our study, we developed a method with which we assessed the potential of peptide ligands to specifically bind to receptor overexpressing target cells. Therefore, a microfluidic setup was used where the cellular adhesion of nanoparticles with ligand and of control nanoparticles was observed in parallel under the same experimental conditions.

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A general synthesis of stable ortho-boropinacolato aryl and heteroaryl sulfonamides by directed ortho-metalation (DoM) and either MeOBPin or i-PrOBpin electrophile quench, 3 → 4, is described. A one-pot metalation-Suzuki cross-coupling procedure for the synthesis of biaryls and heterobiaryls, 3 → 5, and a complementary DoM-Ir-catalyzed boronation sequence (Scheme 6 ) are delineated.

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A miniaturized quantitative biotinidase assay has been developed using biotin 6-amidoquinoline as substrate and the 100-fold enhanced fluorescence of 6-amidoquinoline measured using apolar solvents. Amidoquinoline is measured after deproteinization by ethanol/acetone using individual standardisation and solvent resistant microtiter plates. The assay was optimized for end point determinations of biotinidase activities in serum and for newborn screening using dried blood spots.

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Bone marrow transplantation is one type of hematopoietic reconstitution for oncology patients receiving ablative chemotherapy and/or radiation therapy. As an adjunct in the treatment of malignancies, bone marrow transplantation offers a new hope in cancer treatment as new and more aggressive therapies are used. The underlying principles and stages of bone marrow transplantation are common to the three different types of transplants.

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The attempts to explain the origin of natural optical activity through external, extrabiological, agents, typically ionizing rays, i.e. as a purely incidental effect without deeper significance, have failed and should be abandoned.

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Probably the first nitrogen fixers were anaerobic, non-photosynthetic, bacteria, i.e. fermenters.

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An evolutionary explanation is sought for the fact that ATP is needed for N2 fixation in spite of the exergonicity of the process. After a survey of the state of knowledge about the thermodynamics of N2 fixation in fermenters, photosynthesizers and respirers it is suggested that nitrogenase, which still shows ATP-dependent hydrogenase activity, evolved from an ATP-requiring hydrogenase that lacked nitrogenase activity. The hydrogenase action in the Archaean, reducing, biosphere may have needed ATP to ensure expulsion of H2.

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The influence of 10(-4) divalent cations on the uptake of labelled Zn in the concentration range 10(-5) to 5 x 10(-5) M into the interior of Chlorella fusca at 30 degrees C was measured during 75 min. The Zn absorbed on the surface or contained in the free space was removed by washing with EDTA. Corrections were applied for the loss in concentration due to surface adsorption, etc.

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In experiments on the prebiotic formation of nitric oxides, anoxic mixtures of N2 and water vapour were sparked in contact with phosphate buffer solutions at various pH values. Nitrite was found in the aqueous phase, and nitrate grew from it, presumably by reaction with H2O2. In acid solutions, these anions were reduced and destroyed by Fe2+, and the same was true of nitrite in solutions kept at a pH value similar to that of the contemporary ocean (8.

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Chlorella fusca was grown asynchronously for 2 weeks in media with different Zn concentrations up to 10(-3) M. Growth was optimal at 10(-5) M Zn. The Zn contents of the algae were followed by activation analysis.

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The development of the complicated mechanisms for N2 fixation, which in nature is an endergonic process and requires a great deal of ATP, must have taken a long time. During that time primeval NH3 must still, albeit to a decreasing extent, have been available as a source of nitrogen. This is true, whether N2 fixation originally arose in the primitive anaerobes, or, according to Postgate, in more advanced bacteria.

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Egami's hypothesis that oxygen respiration evolved from nitrate respiration, and this from nitrate fermentation, is not accepted. The reasons are: (1) Presumably there was no nitrate before O2 in the biosphere. (2) On mechanistic grounds, respiration (oxidative phosphorylation) is to be derived directly from photosynthesis (photosynthetic phosphorylation) rather than from any form of fermentation.

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Sulphate uptake by Anacystis nidulans under aerobic conditions in the light was found to be sensitive to metabolic poisons, such as N,N'-dicyclohexylcarbodiimide and carbonyl cyanide m-chlorophenyl hydrazone. It was also depressed by darkness. The sulphate absorption is an energy-dependent process.

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Two groups of lithotrophic bacteria, the existence of which may be expected on evolutionary and thermodynamical grounds, have not yet been detected: (A) photosynthetic, anaerobic, ammonia bacteria, analogous to coloured sulphur bacteria, and (B) chemosynthetic bacteria that oxidize ammonia to nitrogen with O2 or nitrate as oxidant.

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The uptake of labelled zinc into the interior of synchronous Chlorella fusca was measured at 30 degrees C in minimal and optimal conditions (dark/nitrogen or light/air, respectively). No saturation with Zn was reached during 10 hours. Uptake strongly depended on the stage of the cells during the development cycle.

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When in the primeval atmosphere ammonia approached exhaustion, bacteria resembling clostridia developed mechanisms for nitrogen fixation. The fixation was continued by the photosynthetic bacteria. In the later, oxidizing, atmosphere the combined activities of the nitrificants and the denitrificants could lead to a large-scale cyclic regeneration of free nitrogen.

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There is no evolutionary continuity between photochemical abiosynthesis and bacterial photosynthesis. Rather, the photosynthetic bacteria are descendants of fermenters that did not use light. Photosynthesis and respiration, both using electron flow coupled with phosphorylation, have a common origin ('conversion hypothesis'), but photosynthesis came first.

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