bluuebunny/crossref_metadata_2025_split huggingface dataset:
Regulation of hydrolase formation and phosphate release in turimycin fermentations
Authors: Müller P. J. , Ozegowski J. H. , Bocker H. 
Published: July 2010

AbstractDuring the turimycin fermentation hydrolytic enzymes are excreted responsible for orthophosphate release from phosphate‐containing dissolved and undissolved complex medium constituents. Following a phosphate‐limited growth period the phosphate release leads to a second growth period (diauxic growth). Depending on the rate of phosphate release the length of the lag phase of diauxic growth changes in different fermentations.The resulting second growth period is correlated with a transient delay in the formation of turimycin, of phosphatases and of nucleases.The amylolytic activities are formed already within the first hours after the beginning of fermentations. Phosphatases, nucleases and protease are excreted parallel to turimycin formation after extracellular phosphate limitation in presence of ammonia and glucose. A special role of phosphate limitation initiating enzyme synthesis is proposed.
Cellulolytic enzymes associated with the fruit rots of Citrus sinensis caused by Aspergillus aculeatus and Botryodiplodia theobromae
Authors: Adisa V. A. , Fajola A. O. 
Published: July 2010

AbstractBotryodiplodia theobromae and Aspergillus aculeatus were inoculated in carboxymethylcellulose (CMC) medium and on filter papers. Hydrolysis of the CMC medium and degradation of the filter papers were observed, indicating the production of C1 and Cx cellulases by the two rot pathogens. The C1 and Cx enzymes were also detected in filtrates of rotted orange fruits obtained by infection with the two pathogens.The cellulases could not induce rot development on their own. However, when they were added to pectinases in an enzyme inoculum, the incubation period for inducing rot development was shorter, thus establishing a secondary role for the cellulases in the rot development. Optimum conditions for the action of the cellulases included a neutral pH and temperature ranging from 25 to 30 °C.
Biologische Wirkungen von Koordinationsverbindungen der Übergangsmetalle β‐Lactamasen‐inhibitorische Wirksamkeit von Cis‐Platin, 2‐Aminopyridin‐palladium‐chlorid, Clavulansäure und Penicillansäure‐Sulfon CP 45 899 im Nitrocefin‐Test und TITERTEK/Microtiter‐Automatensystem
Authors: Fleck W. F. , Heyn B. , Schröer H.‐P. 
Published: July 2010

AbstractThe β‐lactamase‐inhibiting activity of 6m‐ethyl‐pyrid‐2‐yl‐ammine palladium‐dichloride (Pd 25 681) and cis‐dichloro‐diammine‐platinum (II) was studied and compared with the enzyme inhibitory action of potassium clavulanate and the penicillanic acid sulfone CP 45899. Using the nitrocefin test method and the TITERTEK/Microtiter equipment CP 45 899 and potassium clavulanate were the strongest inhibitors of the Bacillus cereus β‐lactamase. Cis‐dichloro‐diammine‐platinum(II) was fourfold less active than the palladium complex Pd 25 681 in äquimolar concentration. The following ID50 values were found: CP 45 899: 0.0281 μg; K‐clavulanate: 0.1274 μg; Pd 25 681: 3.8603 μg; cis‐dichlorodiammine‐platinum(II): 12.5120 μg/100 μl.
Sekundärmetabolite als endogene Effektoren der mikrobiellen Cytodifferenzierung
Authors: Gräfe U. 
Published: July 2010

AbstractThe present survey covers the regulatory role of microbial secondary metabolites and related compounds as endogenous signals of cell differentiation of the producing organisms. Several antibiotics have been shown to exert autoregulatory effects on differentiation‐associated functions. The mechanisms of self‐protection of the producing cells against the autotoxicity of secondary metabolites are discussed in terms of an integral part of the modulation of signal strength. As a further topic, the review deals with the hormone‐like interference of particular metabolites with differentiating cells. Conclusive discussion concerns the potential use of microbial signal molecules either as tools for directed manipulations of product syntheses or as pharmaceutics.
Replikation und Expression des Plasmids pBR 322 während diskontinuierlicher Kultivierung eines stringent und relaxed kontrollierten Stammes von Escherichia coli
Authors: Hecker M. , Wiehle W. , Schroeeter A. , Mach F. 
Published: July 2010

AbstractThe E. coli strains CP78 and CP79 carrying the plasmid pBR 322 display similar growth kinetics in discontinuous culture. During limitation of amino acids the stringent strain CP78 is able to synthesize guanosine‐5′ diphosphate‐3′‐diphosphate (ppGpp) and guanosine‐5′‐triphosphate‐3′diphosphate, but the relaxed strain can not produce highly phosphorylated guanosine nucleotides. During the logarithmic phase of growth both strains contain similar amounts of plasmid DNA. During amino acid starvation plasmid DNA is amplified in the relaxed strain only, whereas in the stringent strain the plasmid content per cell remains constant.In stationary phase cells of CP78 a higher activity of plasmid‐coded β‐lactamase than in CP79 cells was detected. Furthermore, remarkable differences between both strains were observed in the composition of proteins derived from the periplasmic fraction and separated by polyacrylamide gel electrophoresis.Our results might indicate a negative control of pBR 322 DNA replication by ppGpp during amino acid starvation.
Wirkung supraoptimaler Temperaturen auf Wachstum und Entwicklung einer Brennereihefe II. Wachstum und Entwicklung der Hefe Saccharomyces cerevisiae, Stamm 193, bei kontinuierlicher Kultivierung im pH‐stat
Authors: Mavrina L. , Pozmogova I. , Rabotnova I. , Schade W. 
Published: July 2010

Long term influence of a submaximal temperature (39.5 °C) on a continuous culture of Saccharomyces cerevisiae in a pH‐stat resulted in a reduction of its growth rate from 0.3 h−1 to 0.04 h−1. In consequence of an altered anabolism of the yeast cells a strong and irreversible decrease of the contents of intracellular polymers (DNA, RNA and protein) was stated. Additional changes in the energy metabolism, e.g., the activation of anaerobic pathways of substrate utilization were reversible. A yeast with new physiological features was the results.At short term action of submaximal temperatures during the time of one cell generation only minor changes in the anabolism were found and a fast return of the culture to normal parameters of growth and development was possible.
Microbiological implications of electric field effects VII. Stimulation of plasmid transformation of Bacillus cereus protoplasts by electric field pulses
Authors: Shivarova N. , Förster W. , Jacob H.‐E. , Grigorova R. 
Published: July 2010

AbstractThe aim of this study was to check the action of electric field pulses (1) on the survival of intact cells and protoplasts of Bacillus cereus and (2) on the transformation frequency of these protoplasts with plasmid DNA from Bacillus thuringiensis transformants. – B. cereus cells and protoplasts are very resistant to high electric field pulses in the microsecond range. The transformation frequency of B. cereus protoplasts with plasmids from B. thuringiensis (pUB 110) can be increased by about one order of magnitude with the electric field pulse technique. The transformants are stable and pUB 110 is preserved as an extrachromosomal element.
Influence of tryptophan and related compounds on ergot alkaloid formation in Claviceps purpurea (Fr.) Tul.
Authors: Erge D. , Schumann B. , Gröger D. 
Published: July 2010

AbstractL‐Tryptophan did not exert any influence on peptide alkaloid formation in an ergotamine and in an ergosine‐accumulating C. purpurea strain. A different picture was observed in a series of related C. purpurea strains. Tryptophan showed a slight stimulatory effect on the ergotoxine producer Pepty 695/S. A blocked mutant of it, designated as Pepty 695/ch which was able to accumulate secoclavines gave similar results. In a high‐yielding elymoclavine strain Pepty 695/e, the progeny of the former one, tryptophan up to a concentration of 25 mm stimulated remarkably clavine biosynthesis. Furthermore, tryptophan could overcome the block of synthesis by inorganic phosphate. Increased specific activities of chanoclavine cyclase but not DMAT synthetase were observed in cultures of strain Pepty 695/e supplemented with tryptophan. 5‐Methyltryptophan and bioisosteres of tryptophan were ineffective in alkaloid stimulation. These results are compared with those obtained with the grass ergot strain SD 58 and discussed with the relation to other induction phenomena.
Formation, growth and regeneration of incomplete cell wall in spheroplasts of the blue‐green alga Anacystis nidulans in liquid media
Authors: Gabriel M. 
Published: July 2010

AbstractGrowing cells of blue‐green alga, Anacystis nidulans, were treated with lysozyme in osmotically stabilized nutrient medium. Their development and regeneration ability was studied in liquid media. During 5–8 hrs about 95% of cells were converted to osmotically sensitive spheroplasts having a residual wall layer on their surface. The highest viability of spheroplast population was achieved using egg‐white lysozyme for spheroplast preparation and gradual dilution by nutrient medium instead of centrifugation for lysozyme removal. Most of such prepared spheroplasts survived for 3 days of cultivation in nutrient medium, and started to die gradually from 3 to 10 days. Spheroplasts were growing spherically, about 30% of them were growing for 8 days up to 40‐fold increase in volume. Multiplication of thylakoid cisternae in growing spheroplasts was proved by freezeetching. Electron microscopy further revealed newly synthesized amorphous walls of isodiametrical appearance by growing spheroplasts resembling the original cell walls of cells. In liquid media blue‐green alga spheroplasts of Anacystis nidulans can grow for a number of days, however, only regeneration of incomplete wall occur unable to promote reversion of spheroplasts to cells.
Verbreitung methanotropher Bakterien
Authors: Heyer J. , Malashenko Yu. , Berger U. , Budkova E. 
Published: July 2010

AbstractThis paper reports on the investigations of the distribution of the methanotrophic bacteria in various environments and geographic zones. In the most of about 1000 samples investigated by us obligately methanotrophic bacteria were found. More than 300 pure cultures were isolated, among them strains of all five groups of methanotrophs described by Whittenbury et al. (1970). There were great differences in their distribution patterns in several habitats. The occurrence of methanotrophic bacteria even in acidophilic peat bog lakes and in salt‐lakes shows the great ecological amplitude of this group of organisms.Experiences with the use and the interpretation of the MPN‐method for the enumeration of methanotrophic bacteria are presented. The results of the quantitative investigations enlarge the knowledge about the distribution of these organisms in various natural and artifical habitats and confirm their high frequency in the nature.The greatest densities of cells are found in sewage, but only small numbers of cells in the open water and sandy sediments of Baltic Sea and in salt‐lakes. Generally the frequency of the methanotrophic bacteria was closely related to the concentration of methane, respectively, to the rate of methane release in the habitat. The high numbers of cells in the aerobic layers of sediments are an indication of the great activity of the aerobic methane oxidation in these zones.
Characterization of carbon nanotube filters and other carbonaceous materials by Raman spectroscopy—II: study on dispersion and disorder parameters
Authors: Heise H. M. , Kuckuk R. , Srivastava A. , Asthana B. P. 
Published: July 2010

AbstractRecently, we have reported on the characterization of various carbonaceous materials including multiwalled carbon nanotube (MWCNT) filters, which have specific molecular filtering capabilities and good mechanical strength and can be produced in bulk as highly aligned arrays of bundles of CNTs. We have extended our studies using Fourier transform‐Raman spectroscopy with 1064 nm excitation wavelength and a rotating sample holder in the region 1000–2800 cm−1, in addition to 532 and 785 nm, which were used for Raman excitation in our previous study. Raman spectra were analyzed for band positions and line shape with special emphasis on the D‐, G‐ and G′‐ bands. For the single‐walled species, Carbotrap and graphite spectra were also recorded with 488 nm excitation. A dispersion study has been made from the Raman data available with the different excitation wavelengths. Slight band shifts and band broadening could be observed under the two sample conditions, one with the stationary sample and the other with sample rotation. The spectral changes are related to the excessive heating caused in a stationary sample by laser irradiation. Based on our findings in this study combined with our earlier study, we can state that only a careful line shape analysis and study of intensity pattern of the D‐ and G‐Raman bands under well‐defined measurement conditions lends itself as a good measure of degree of alignment in the MWCNT bundles. Copyright © 2010 John Wiley & Sons, Ltd.
Electrospun, Biofunctionalized Fibers as Tailored in vitro Substrates for Keratinocyte Cell Culture
Authors: Grafahrend Dirk , Heffels Karl‐Heinz , Möller Martin , Klee Doris , Groll Jürgen 
Published: July 2010

AbstractCell adhesion preventing fiber surfaces were tailored differently with bioactive peptides (a fibronectin fragment (GRGDS), a collagen IV fragment (GEFYFDLRLKGDK) and a combination of both) to provide an artificial extracellular matrix as a substrate for HaCaT keratinocyte cell culture. Therefore, a polymer blend containing a six‐arm star‐shaped statistical copolymer of ethylene oxide and propylene oxide in the ratio 80:20 (NCO‐sP[EO‐co‐PO]) and poly‐[D,L‐(lactide‐co‐glycolide)] (PLGA) was electrospun. The resulting fibers were biofunctionalized and investigated as in vitro substrates using the HaCaT kerationcyte cell line. Appropriate surface chemistry on these electrospun fibers proved to prevent adhesion of keratinocytes, while additional immobilization of certain peptide sequences induced cell adhesion. These specific fibers enable investigation of immobilized active molecules and the subsequent cellular response to the scaffold. HaCaT keratinocytes were found to selectively adhere to those fibers modified with either collagen IV segment GEFYFDLRLKGDK or a mixture of the two peptide sequences GEFYFDLRLKGDK and GRGDS (1:1). However, the synergistic effects of both (the fibronectin fragment and the collagen IV fragment) seem to significantly increase the numbers of adherent keratinocytes.magnified image
Imidazole and Dimethyl Aminopropyl‐Functionalized Hyperbranched Polymers for Nucleic Acid Transfection
Authors: Germershaus Oliver , Pickaert Guillaume , Konrad Juliane , Krüger Ute , Kissel Thomas , Haag Rainer 
Published: July 2010

AbstractIn order to mimic the histidine binding motives of naturally occurring histones as DNA complexing proteins, hyperbranched poly(ethylene imine) and polyglycerol were functionalized with imidazole or 3‐dimethylamino propyl groups. These new polycationic polymers were tested for interaction with dye‐labelled oligonucleotide and DNA using UV and fluorescence spectroscopy and gel electrophoresis. Formation of stable complexes was observed above N/P ratios of 4 for unfunctionalized and 8 for functionalized PEIs. No stable complexes were formed with polyglycerol‐based polyamines up to N/P 16. Cytotoxicity determined by MTT assay of all functionalized PEI polymers was found to be significantly lower than for unfunctionalized PEI. PG‐based polymers showed no toxicity in the tested concentration range. Dynamic light scattering showed that only for PEI21‐Imidaz polyplexes hydrodynamic diameters below 250 nm could be reached.The influence of functionalization and polymer type on transfection efficiency was evaluated in L929, NIH/3T3 and HeLa cells. Only imidazole‐functionalized PEIs reached similar transfection efficiencies as unfunctionalized PEIs, while 3‐dimethylamino propyl modification resulted in lower transfection efficiencies. We also demonstrated that the polymer plays an important role for transfection properties since, regardless of the modifications of polyglycerol, only low transfection efficiencies were observed at functionalization levels below 50%.magnified image
Multiscale Modeling of Branch Length in Butyl Acrylate Solution Polymerization
Authors: Rawlston Jonathan A. , Schork Francis Joseph , Grover Martha A. 
Published: July 2010

AbstractBranch lengths resulting from both backbiting and intermolecular chain transfer to polymer are examined for the solution polymerization of butyl acrylate, using a rate‐equation model and ordinary differential equations. Backbiting is allowed to generate branches of varying length, according to a cumulative distribution function obtained from a lattice kinetic Monte Carlo simulation. About 8% of the branches produced by backbiting are 10 mers or longer. In contrast to common assumptions about the origins of short‐chain and long‐chain branches, the model indicates that nearly all of the long‐chain branches may be produced by backbiting, rather than intermolecular chain transfer to polymer.magnified image
Another look at the contingency tables: scores based on Manhattan distances in the phase space
Authors: Stein Joël 
Published: July 2010

AbstractThis alternative presentation of scores is based on the Manhattan distance in the phase space of forecasts. The key factor is represented by the ratio of the weights assigned to misses and false alarms. This ratio is 1 for the Heidke skill score and is equal to the ratio of the number of non‐events to the number of events for the Pierce skill score. A score based on the deterministic limit leads to assign this ratio to either 2 or 0.5 as a function of the base rate. It can also be determined as a function of parameters of a cost‐loss economical model.Applied to the Finley tornadoes and to two quantitative precipitation forecasts, the geographical representation of the phase space is quite invaluable as it points out the good points and the drawbacks of the forecast. The skill scores deduced from these distances help to summarize the quality of a forecast. Copyright © 2010 Royal Meteorological Society
Comparison of the quantitative first pass myocardial perfusion MRI with and without prospective slice tracking: Comparison between breath‐hold and free‐breathing condition
Authors: Cleppien Dirk Ernst Johannes , Horstick Georg , Abegunewardene Nico , Weber Stefan , Müller Christian Ernst , Heimann Axel , Kreitner Karl‐Friedrich , Kempski Oliver , Schreiber Laura Maria 
Published: July 2010

AbstractPhysiologic motion of the heart is one of the major problems of myocardial blood flow quantification using first pass perfusion–MRI method. To overcome these problems, a perfusion pulse sequence with prospective slice tracking was developed. Cardiac motion was monitored by a navigator directly positioned at heart's basis to overcome no additional underlying model calculations connecting diaphragm and cardiac motion. Additional prescans were used before the perfusion measurement to detect slice displacements caused by remaining cardiac motion between navigator and the perfusion slice readout. The pulse sequence and subsequent quantification of myocardial blood flow was tested in healthy pigs with and without prospective slice tracking under both free‐breathing and breath‐hold conditions. To avoid influences by residual contrast agent concentration time courses were analyzed. Median myocardial blood flow values and interquartile ranges with prospective slice tracking under free‐breathing and in a breath‐hold were (1.04, interquartile range = 0.58 mL/min/g) and (1.20, interquartile range = 0.59 mL/min/g), respectively. This is in agreement with published positron emission tomography values. In measurements without prospective slice tracking (1.15, interquartile range = 1.58 mL/min/g), the interquartile range is significantly (P < 0.012) larger because of residual cardiac motion. In conclusion, prospective slice tracking reduces motion‐induced variations of myocardial blood flow under both during breath‐hold and under conditions of free‐breathing. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
Optimal design of periodic test input signals for multivariable impulse response models
Authors: Kaisare Niket S. , Lee Jay H. 
Published: July 2010

AbstractThis paper considers an optimal test input design problem occurring in a control‐relevant, iterative system identification scheme. The optimization is based on minimizing the expecteda posterioriclosed‐loop error based on thea prioriinformation given by the data already collected. Instead of directly solving the resulting non‐linear optimization to obtain the test input sequences, two different computationally efficient approaches are proposed. The first approach is cast in the frequency domain and we solve for optimal discrete spectra of the periodic signals under some reasonable approximation. The solution can be realized as an input sequence by performing a spectral factorization and implementing the spectral factor as a digital Finite Impulse Response (FIR) filter. A second approach is suggested by reformulating the optimal design problem as a linear matrix inequalities (LMI) problem. The efficacy of these approaches is demonstrated through a numerical example. Copyright © 2010 John Wiley & Sons, Ltd.
Determinants of fentanyl and other potent µ opioid agonist misuse in opioid‐dependent individuals
Authors: Cicero Theodore J. , Ellis Matthew S. , Paradis Alethea , Ortbal Zachary 
Published: July 2010

AbstractPurposeBased on preclinical and clinical abuse liability assessments, fentanyl and other potent µ opioid agonists (e.g., hydromorphone and morphine) should be the most misused opioids if accessibility in the real world were not an issue. Since the latter is seldom true, we postulated that there would be a significant mismatch between actual and predicted rates of misuse.MethodsWe recruited 1818 prescription‐opioid dependent patients entering drug treatment programs to complete an anonymous survey, covering drug use and health related issues.ResultsHydrocodone and oxycodone products were the drugs of choice in 75% of patients, whereas potent µ opioid agonists (fentanyl, hydromorphone, and morphine), with the greatest predicted abuse potential, were very rarely chosen (<5% each). Most unexpectedly, the rank order of the actual drug of choice and the preferred drug in an ideal world were highly correlated. The reason most commonly given for the failure to endorse fentanyl, for example, as an actual or preferred drug, was fear of toxicity and overdose. We found few differences in drug use patterns between a subset of high‐risk, impaired health care professionals (N = 196), and all other patients other than source of drug (forged prescriptions and doctors more common and dealers much less common in the HC sample).ConclusionsThese results indicate that it should not be assumed – particularly for new drug formulations – that a high potential for abuse will result in actual abuse; and, most importantly, that the hesitancy to use potent opioids because of fears of abuse may be misguided. Copyright © 2010 John Wiley & Sons, Ltd.