bluuebunny/crossref_metadata_2025_split huggingface dataset:
Malignant‐lesion segmentation using 4D co‐occurrence texture analysis applied to dynamic contrast‐enhanced magnetic resonance breast image data
Authors: Woods Brent J. , Clymer Bradley D. , Kurc Tahsin , Heverhagen Johannes T. , Stevens Robert , Orsdemir Adem , Bulan Orhan , Knopp Michael V. 
Published: February 2007

AbstractPurposeTo investigate the use of four‐dimensional (4D) co‐occurrence‐based texture analysis to distinguish between nonmalignant and malignant tissues in dynamic contrast‐enhanced (DCE) MR images.Materials and Methods4D texture analysis was performed on DCE‐MRI data sets of breast lesions. A model‐free neural network‐based classification system assigned each voxel a “nonmalignant” or “malignant” label based on the textural features. The classification results were compared via receiver operating characteristic (ROC) curve analysis with the manual lesion segmentation produced by two radiologists (observers 1 and 2).ResultsThe mean sensitivity and specificity of the classifier agreed with the mean observer 2 performance when compared with segmentations by observer 1 for a 95% confidence interval, using a two‐sided t‐test with α = 0.05. The results show that an area under the ROC curve (Az) of 0.99948, 0.99867, and 0.99957 can be achieved by comparing the classifier vs. observer 1, classifier vs. union of both observers, and classifier vs. intersection of both observers, respectively.ConclusionThis study shows that a neural network classifier based on 4D texture analysis inputs can achieve a performance comparable to that achieved by human observers, and that further research in this area is warranted. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
Connexin 43 gap junction proteins are up‐regulated in remyelinating spinal cord
Authors: Roscoe W.A. , Messersmith E. , Meyer‐Franke A. , Wipke B. , Karlik S.J. 
Published: February 2007

AbstractAlterations in the expression of gap junction proteins have previously been observed in several diseases affecting the central nervous system; however, the status of connexin 43 (Cx43) has not yet been reported in spinal cord remyelination. We studied Cx43 expression in demyelination and remyelination by using a chronic guinea pig model of experimental allergic encephalomyelitis (EAE). Hartley guinea pigs were immunized with homogenized whole CNS and complete Freund's adjuvant. Animals became chronically ill by day 40 postimmunization, and animals with paralysis were entered into the study. Animals were treated on days 40–60 postimmunization with either saline or drugs that promote remyelination: an adenosine amine congener (100 μg/kg), an anti‐α4‐integrin blocker (CT301; ELN 69299; 30 mg/kg), or a combination of both drugs. Remyelination was induced in all drug‐treated groups. Cx43 expression was virtually absent in demyelinated lesions of saline‐treated controls compared with healthy tissue and normal appearing white matter (P < 0.001), whereas Cx43 was considerably increased (300–500%) in remyelinating lesions of all treatment groups (P < 0.001), most notably in CT301‐treated animals. These changes in Cx43 expression indicate that Cx43 may beimportant for recovery from neuroinflammation. © 2007 Wiley‐Liss, Inc.
Yield coefficients in dependence on milieu conditions and cell states IV. Ethanol production by yeasts. Yield coefficients. IV
Authors: Heinritz B. , Ghildyal N. P. , Ringpfeil M. 
Published: February 2007

AbstractThe effect of yeast‐cell state on the rate and yield of ethanol synthesis in semicontinuous and continuous fermentation of carbohydrates was investigated in order to increase the ethanol production rates and to obtain ethanol yields close to theoretically calculated values.Differences between the initiation of ethanol synthesis in cells of the single‐cell state and of the budding‐cell state were obtained. It could be shown that it is advantageous to switch to anaerobic conditions for ethanol production when yeast cells enter the budding‐cell state during aerobic cultivation.Thus, by considering cell‐state distribution of yeast population the specific ethanol production rate and the total ethanol yield could be improved in continuous sucrose fermentation by Saccharomyces cerevisiae H 155. The cell‐state distribution was changed by replacement of aged cells in the single‐cell state by aerobically precultivated budding cells which caused an increased process stability.These results show that investigations of the dependence of yield and rate of ethanol production on cell states are a powerful means to intensify the ethanol production.
Metabolism of sulfur‐containing amino acids in the dermatophyte Microsporum gypseum I. Neutral amino acids
Authors: Kunert J. 
Published: February 2007

AbstractThe dermatophyte Microsporum gypseum was cultivated on a glucose‐arginine medium to which on out of six sulfur‐containing amino acids was added (l‐cystine, l‐djenkolic acid, dl‐lanthionine dl‐homocystine, l‐methionine, or l‐methionine‐sulfone at a concentration of 5 mm with respect to sulfur content). The addition of these substances did not stimulate the growth and some amino acids (djenkolic acid and particularly methionine and methionine‐sulfone) were inhibitory. All tested compounds were utilized during the growth not only as sulfur source but as a source of carbon and nitrogen as well. In four substrates excess sulfur was excreted after oxidation into the medium in the form of sulfate. Small amounts of sulfite were also observed. It usually reacted with remaining disulfides in the medium forming S‐sulfo compounds (R‐S.SO3H). Cystine and djenkolic acid were oxidized rapidly and completely. In contrast, lanthionine and particularly homocystine were oxidized slowly and only after a longer adaptation. To some extent lanthionine was already oxidized extracellularly in the medium. With methionine and its sulfone, excess sulfur was not removed by oxidation but by demethiolation to methane thiol and further volatile products.
Geförderte Plaquebildung in RNA‐Phagen/Bakterien‐Systemen unter dem Einfluß oberflächenaktiver Präparate
Authors: Menzel G. 
Published: February 2007

AbstractThe effect of 21 surfactants on the plaque formation was tested in three RNA‐phages/Escherichia coli systems and in one RNA‐phage/Psedomonas aeruginosa system. Especially anionic detergents proved to be able to influence the plaque formation substantially. In high concentrations of Metaupon, Fekunil 602, Fekunil S‐BA, Emulgator W 270, and Emulgator O‐BA the plaque formation by the phages M 12 and f 2 was inhibited and in low concentrations it was promoted. In the system Qβ/E. coli AB 301 the effect of the detergents mentioned was restricted to the prevention of the appearance of plaques. The detergent E 30 brought about only plaque inhibitions, too, in all used RNA‐phages/E. coli systems. The treatment with effective detergents in the system PP7/P. aeruginosa, however, increased only the number of plaques.This phenomenon was evident in the formation of radiate plaque patterns in the lawn of bacteria. In the case of RNA‐phages of E. coli the formation of such trains of lysis depends on the choice of the nutritive medium. The addition of the detergent Fekunil 602 at different times after the contact between phages and host bacteria affects the length of the beams of lysis. The ionogenity of surfactants seems to be of importance for the formation of radiate plaque patterns, since the tested cationic compound and the nonionic surfactants, contrary to anionic surfactants, did not cause any beams of lysis.
An electrochemical method for determination of cell respiration
Authors: Riedel K. , Liebs P. , Renneberg R. 
Published: February 2007

AbstractThe respiration of microorganisms was determined with a sensor composed of microorganisms and an oxygen electrode. The microorganisms (suspensions of about 100 μl) are sedimented by centrifugation in a special tube on a very thin paper layer (diameter 4 mm). This paper layer is sandwiched between a polyethylene membrane and a dialysis membrane. A linear relationship is obtained between the current and the cell mass of Bacillus subtilis (between 0.05–0.35 mg dry weight per electrode preparation). When an assimilable substrate is added to the measuring solution the respiration rate is increased. It is possible to determine very fast changes in the respiration rates (1–5 sec). The application of this electrode system for investigations of the physiological state of cells during the growth cyclus is demonstrated.
Proteine der Zellwand von Escherichia coli: Eine dem thermolabilen Enterotoxin (LT) ähnliche Substanz
Authors: Seltmann G. , Beer W. , Voigt W. , Wolter E.‐J. , Grahlow W.‐D. 
Published: February 2007

AbstractIn ultrasonic extracts of all 19 investigated non‐enterotoxigenic E. coli strains a substance (LTLS) could be detected reacting positively in all tests which are commonly used to detect specifically E. coli thermolabile enterotoxin (LT). Culture supernatants of these strains in general did not contain LTLS in detectable amounts. LTLS can be found in the whole cell, however, the membrane fraction contains the highest quantities. Released LTLS appears mainly aggregated with components of the cell wall, especially with lipopolysaccharides. This fact in combination with the very low quantities produced by the bacteria renders very difficult purification of LTLS.
Denitrifikation mit Cellulose als einzigem Wasserstoffdonator
Authors: Sommer K. , Ottow J. C. G. 
Published: February 2007

AbstractWith cellulose as a single energy source (hydrogen donator) and nitrate as an electron acceptor, 18 strains of denitrifying bacteria were isolated by enrichment technique and identified as members of Cellulomonas sp. (6 strains), Pseudomonas fluorescens (6) and Acinetobacter‐Moraxella sp. (3). Three gram‐negative rods could not be classified so far. In model experiments (Fig. 1) with a synthetic cellulose‐KNO3‐broth (pH 7.3) denitrification (N2, N2O) was followed (Fig. 2 and 3) using Cellulomonas sp. strain 20 and Pseudomonas fluorescens nr. 15, respectively, as test organisms. Under complete anaerobic conditions, no denitrification occurred. However, in the presence of oxygen (12.5 vol.‐% O2) both respiration and denitrification (N2 and N2O) could be ascertained by gaschromatography. Rapid increase in CO2 confirmed active cellulolytic activity (Fig. 2 and 3).
Untersuchungen zur Regulation der Ammoniumassimilation von Candida maltosa
Authors: Casper P. , Bode R. , Birnbaum D. 
Published: February 2007

AbstractActivities of ammonia‐metabolizing enzymes from Candida maltosa were measured. The synthesis of glutamate and glutamine involves three primary enzymes: glutamate dehydrogenase (GDH), glutamine synthetase (GS), and glutamate synthase (GOGAT). This yeast has two distinct GDH, the first responsible for glutamate catabolism, and the second solely biosynthetic. The GS is derepressed during growth on low ammonia or on a variety of alternative nitrogen sources, whereas the catabolic GDH (NAD) is repressed under this conditions. Ammonia limitation did not significantly affect GOGAT as well as biosynthetic GDH (NADP) levels. The relatively low Km‐value for ammonia suggest that the GS is catalytically active during cell growth on low concentrations of ammonia. It seems that under N‐limitation ammonia assimilation is achieved via GS/GOGAT and under N‐excess via GDH/GS.
Metabolism of sulfur‐containing amino acids in the dermatophyte Microsporum gypseum II. Acidic amino acid derivatives
Authors: Kunert J. 
Published: February 2007

AbstractThe dermatophyte Microsporum gypseum was cultivated on a glucose‐arginine medium supplemented with five strongly acidic derivatives of cysteine (l‐cysteine sulfinic acid, l‐cysteic acid, l‐serine‐0‐sulfate and taurine at a concentration of 5 mmol/l, and l‐S‐sulfocysteine at a concentration of 2.5 mmol/l). The addition of these substances did not stimulate the growth as compared with the control containing 0.5 mmol/l cystine. Cysteine sulfinic acid and cysteic acid showed rather inhibitory effects. A strong inhibition of the growth was caused by the presence of serine sulfate. During the growth, all substances investigated were gradually consumed and utilized not only as a source of sulfur but of nitrogen and carbon as well. Cysteine sulfinic acid and S‐sulfo‐cysteine were utilized most rapidly. Cysteic acid was also rapidly utilized but after a certain adaptation. Taurine was utilized slowly and serine sulfate very slowly. Excess sulfur contained in the substances used was excreted into the medium in the form of sulfate. Sulfate excretion was most rapid with cysteine sulfinic acid and slowest with taurine. With cysteine sulfinic acid, S‐sulfocysteine and cysteic acid, small amounts of sulfite were found in the medium. The results obtained are in accordance with the presumption that cysteine sulfinic acid (but not cysteic acid and taurine) is an intermediate of cysteine catabolism in dermatophytes.
Transformation of the industrially important yeasts Candida maltosa and Pichia guilliermondii
Authors: Kunze G. , Petzoldt C. , Bode R. , Samsonova I. A. , Böttcher F. , Birnbaum D. 
Published: February 2007

AbstractSaccharomyces cerevisiae, Candida maltosa and Pichia guilliermondii have been transformed at different frequencies by the plasmid p Ye(ARG4)411 which carried the Sacch. cerevisiae ARG4 gene inserted into pBR322. Our results strongly suggest that the transformants possessed extrachromosomally maintained and autonomously replicating plasmid DNA from which ARG4 gene and β‐lactamase gene were expressed.
Electron microscopic study of purified polysaccharide components glucans and mannan of the cell walls in the yeast Saccharomyces cerevisiae
Authors: Kopecká Marie 
Published: February 2007

AbstractIn this study electron‐microscopic characteristics of platinum shadowed or negatively stained preparations of purified β‐(1 → 3)‐d‐glucan, β‐(1 → 6)‐d‐glucan, and mannan were examined. These polysaccharides were isolated from cell walls of the yeast Saccharomyces cerevisiae. While purified samples of β‐(1 → 6)‐d‐glucan and mannan proved to be amorphous in structure and homogenous in appearance, the purified β‐(1 → 3)‐d‐glucan, isolated and presented to us as alkali‐insoluble yeast glucan A2, was not homogenous. It consisted of (i) fibrillar component, (ii) amorphous matrix, and (iii) chitin bud scars. The ultrastructure of β‐(1 → 3)‐d‐glucan present in the glucan A2 sample did not change after treatment with 0.5 m acetic acid at 75°C for 2 hours. After treatment with 1 m NaOH for 3 days at 4 °C scar material was removed by centrifugation and after a subsequent acidification of supernatant with acetic acid both the microfibrillar and the amorphous components were still present. It was concluded that β‐(1 → 3)‐d‐glucan component consists of molecules probably differing in their physico‐chemical properties such as D. P., the degree of branching, conformation, and that cannot be separated by the methods currently used for their isolation.
Charakterisierung und Differenzierung fluoreszierender Pseudomonaden mit Hilfe von Substratverwertungsstudien
Authors: Schöpp W. , Toaspern Cornelia , Tauchert H. 
Published: February 2007

AbstractA rapid procedure is described for detecting and differentiating pseudomonads by their ability to degrade substrates with diverse physico‐chemical properties, including volatile and non‐volatile water‐insoluble compounds, strong organic acids and bases, surfactants, disinfectants, and other toxic substances. The bacteria are embedded in an agar medium containing mineral salts and exposed to about 5 mg amounts of six to eight different substrates placed on the surface of an agar plate. After incubation at 25°C for 24 hrs, growth zones around utilizable substrates may be used to differentiate various Pseudomonas strains and species.
Säureausscheidung und Kaliumaufnahme der Hefe Hansenula henricii Hg 48‐2 in Chemostat‐Kulturen bei verschiedenen pH‐Werten
Authors: Uebel B. , Huth J. 
Published: February 2007

AbstractProton release and K+‐content of biomass in chemostat cultures of the yeast Hansenula henricii Hg 48‐2 were measured in 12 steady states at different K+‐concentrations in the medium reservoire (sR) and at different pH‐values in the culture. Competitive inhibition of K+‐uptake by H+‐ions, described for non‐growing yeast cultures, could not be found. The growing cultures show H+/K+ exchange quotients between 8:1 and 40:1. The actual value of the H+/K+ exchange quotient is determined by the relation between the NH+4‐and the K+‐content in the medium reservoire. The exchange quotient is not influenced by the concentration of biomass and slightly modulated by the pH‐value in the culture. The difference between the H+ excretion and the K+ uptake is caused mainly by the growth‐dependent NH+4 demand. The K+ content of the biomass increases non‐linear with increasing K+ concentrations sR constant pH values. There exists a linear relationship between the yield coefficient YH+ and the biomass concentration in the steady state χ. These findings are discussed as a result of interactions between potassium‐, nitrogen‐and oxygen‐limitation.
Synergistic effect of cobalt on the induction by A‐factor of the formation of aerial mycelium and anthracyclines by a blocked mutant of Streptomyces griseus
Authors: Gräfe U. , Eritt I. , Riesenberg D. 
Published: February 2007

AbstractCobalt ions synergistically supported the inducing effect of A‐factor 1a on the formation of aerial mycelium and anthracyclines by the blocked S. griseus mutant 86. This suggested an involvement of effector 1a in the transport or metabolism of this trace element. In accordance with the proposed role of 1a as an autoregulatory secondary metabolite, the parent strain S. griseus JA 3933 secreted 1a into the medium after a decrease of the specific growth rate and before the onset of antibiotic production.
An esterase as marker enzyme on the outer membrane of Acinetobacter calcoaceticus
Authors: Claus R. , Fischer B. , Kleber H.‐P. 
Published: February 2007

AbstractAn esterase activity which hydrolyses palmitoyl‐CoA was found in the membrane fraction of Acinetobacter calcoaceticus 69/V. Other tested strains of Acinetobacter also possessed this enzyme activity. The esterase is constitutive, fully active on the surface of intact cells and located on the outer membrane of the bacteria. Besides palmitoyl‐CoA some oxy‐esters and p‐nitrophenyl palmitate were also hydrolyzed. In contrast triglycerides, short‐chain acyl‐CoA esters (C2—C10) and p‐nitrophenyl acetate were not hydrolyzed. The enzyme activity was not influenced by inhibitors of mammalian esterases.
Influence of inorganic phosphate on the lipid synthesis of a phosphate‐deregulated mutant of Streptomyces noursei
Authors: Hänel F. , Gräfe U. , Roth M. , Bormann E. J. , Krebs D. 
Published: February 2007

AbstractPhosphate‐dependent changes of the mycelial lipid composition were studied in the streptothricin‐producing parental strain Streptomyces noursei JA 3890 b/2 and its mutant RG 2. In contrast to its ancestor, the mutant was capable of producing the antibiotic nourseothricin even when large quantities of inorganic phosphate were present in the medium. The apparent insensitivity of the secondary metabolism to phosphate inhibition corresponds to a decreased level of phospholipids in the presence of excessive inorganic phosphate and, during phosphate limitation, to a much higher production of the alkaline phosphatases. A model is discussed which proposed the control by a common genetic element of both the phospholipid and antibiotic production.
Interactions between three blue‐green algae and herbicide 2,4‐D in culture media
Authors: Kobbia I. A. , El‐Sharouny H. M. 
Published: February 2007

AbstractNostoc muscorum, Tolypothrix lanata and Aulosira laxa showed different responses to 2,4‐D herbicide at all concentrations. Low concentrations of the herbicide stimulated chlorophyll a synthesis and promoted growth in all species. The maximum values of chlorophyll a contents were recorded at 50 ppm for Nostoc muscorum and Tolypothrix lanata, and at 10 ppm for Aulosira laxa. Above these levels, chlorophyll accumulation was steadily inhibited in all organisms.The nitrogenase activities in the three species were markedly inhibited and the degree of inhibition increased with increasing concentrations. Nitrogenase activities were always higher at anaerobic than at aerobic conditions, a phenomenon that was reversed at higher concentrations of 2,4‐D in Nostoc muscorum.
Expression in Escherichia coli of streptococcal plasmid‐determined erythromycin resistance directed by the cat gene promoter of pACYC 184
Authors: Malke H. , Ferretti J. J. 
Published: February 2007

AbstractThe streptococcal erythromycin resistance (Emr) plasmid pSM7 (6.4 kb) and the E. coli vector pACYC184 (4.0 kb) were fused at their single EcoRI sites to form the bifunctional chimeric plasmid pSM7184 (10.4 kb) in which the Emr determinant was placed under control of the chloramphenicol acetyl transferase (cat) promoter of pACYC184. In the sense orientation (orientation I) of pSM7, the cat promoter directed expression of Emr in the E. coli host strains 294 and DB11 more efficiently than did the indigenous transcription signals of pSM7, which were functional in the opposite orientation II. In Streptococcus sanguis (Challis), the level of Emr was independent of the orientation of pSM7 in pACYC184, showing that the cat promoter was not recognized in the grampositive host. The growth of E. coli (pSM7184I) in a defined medium containing glycerol as carbon source, or containing glucose plus extraneous cyclic 3′–5′ adenosine monophosphate (cAMP) led to an Emr level which was 15–30 times higher than that of cultures grown on glucose. These results showed that under control of the cat promoter, Emr is subject to cAMP‐mediated catabolite repression and provided conclusive evidence that the enhancement of Emr expression in E. coli carrying pSM7184I is controlled at the transcriptional level.Besides enabling us to determine the orientation of transcription of the Emr gene in pSM7 and related vectors, this work also made available new bifunctional cloning vehicles able to replicate in both E. coli and S. sanguis.
Enzym‐Inhibitoren aus Actinomyceten II. Inhibitoren saurer Proteinasen
Authors: Passarge Margrit , Fleck W. F. 
Published: February 2007

AbstractIn the course of a screening program directed toward the isolation and evaluation of inhibitors of carboxyl (acid) proteinases, we have found 0.39% of the investigated strains of microorganisms as producers of pepsin inhibitors. In more than 1543 strains which were isolated from various geographical areas and deposited with the IMET Culture Collection, Jena‐GDR, and which belong to different genera of actinomycetes such as Streptomyces, Actinomadura, Actinoplanes, Micromonospora and non‐identified strains, we have found 6 Streptomyces strains only. Surprisingly, the screening efficiency of the used casein agar spot test and the fibrin‐blue‐technique was very low. As compared with the inhibitor activity of pepstatin the yield of the fermentation broth of 3 wild type strains ranged from 6 to 27 μg/ml. A significant influence of the composition of culture fluids on the inhibitor yield was observed. Supplements by crude glutamine or mixtures of amino acids in culture fluids increased the yield from 3 to 15 times as compared with that of fermentation broth without supplements. After NMG‐mutagenic treatment and use of familiar selection procedures 3.1% inhibitor‐blocked mutants were detected among 480 strains selected.