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  • Cell & Developmental Biology  (8)
  • Chemistry  (3)
  • Adenocarcinoma  (2)
  • Aphanocapsa 6308  (2)
  • Carbon dioxide fixation  (2)
  • Column liquid chromatography  (2)
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Keywords
  • 1
    Electronic Resource
    Electronic Resource
    Therapeutic efficacy of the cyclopropylpyrroloindole, carzelesin, against xenografts derived from adult and childhood solid tumors (1995)
    Springer
    Cancer chemotherapy and pharmacology 36 (1995), S. 45-52 
    Details
    ISSN: 1432-0843
    Keywords: Carzelesin ; Human tumor xenrografts ; Drug resistance ; Adenocarcinoma ; Rhabdomyosarcoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The therapeutic efficacy of the sequence-selective, DNA minor-groove-binding alkylating agent carzelesin was evaluated against a series of human tumor xenografts growing at the s.c. site. The model consisted of seven colon adenocarcinomas, and six pediatric rhabdomyosarcomas. In addition, carzelesin was evaluated against xenografts selected in situ for resistance to vincristine, melphalan, and topotecan. Carzelesin was given as a single i.v. injection, and tumor volumes were determined at 7-day intervals. At the highest dose [0.5 mg/kg, the dose producing 10% lethality (LD10)]), carzelesin significantly inhibited growth in four of six colon tumor lines, causing a high proportion of partial regressions in one of seven lines and complete regressions of VRC5 colon tumors. At 0.25 mg/kg, significant growth inhibition was determined in only two of seven colon tumor lines with infrequent volume regressions. Carzelesin given at the highest nonlethal dose level significantly inhibited the growth of each of six rhabdomyosarcomas, causing a high frequency of partial or complete regressions in four of six tumor lines. There was no apparent cross-resistance to carzelesin in two rhabdomyosarcomas selected for vincristine resistance (Rh12/VCR, Rh18/VCR) or in Rh28/LPAM xenografts selected for primary resistance to the bifunctional alkylating agent melphalan. Interestingly, carzelesin maintained full activity against Rh18/TOPO tumors selected in situ for resistance to topotecan, whereas the colon tumorVRC 5/TOPO, selected in a similar manner, was completely resistant to this agent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00685731
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  • 2
    Electronic Resource
    Electronic Resource
    Therapeutic efficacy of the cyclopropylpyrroloindole, carzelesin, against xenografts derived from adult and childhood solid tumors (1995)
    Springer
    Cancer chemotherapy and pharmacology 36 (1995), S. 45-52 
    Details
    ISSN: 1432-0843
    Keywords: Key words Carzelesin ; Human tumor xenrografts ; Drug resistance ; Adenocarcinoma ; Rhabdomyosarcoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The therapeutic efficacy of the sequence-selective, DNA minor-groove-binding alkylating agent carzelesin was evaluated against a series of human tumor xenografts growing at the s.c. site. The model consisted of seven colon adenocarcinomas, and six pediatric rhabdomyosarcomas. In addition, carzelesin was evaluated against xenografts selected in situ for resistance to vincristine, melphalan, and topotecan. Carzelesin was given as a single i.v injection, and tumor volumes were determined at 7-day intervals. At the highest dose [0.5 mg/kg, the dose producing 10% lethality (LD10)]), carzelesin significantly inhibited growth in four of six colon tumor lines, causing a high proportion of partial regressions in one of seven lines and complete regressions of VRC5 colon tumors. At 0.25 mg/kg, significant growth inhibition was determined in only two of seven colon tumor lines with infrequent volume regressions. Carzelesin given at the highest nonlethal dose level significantly inhibited the growth of each of six rhabdomyosarcomas, causing a high frequency of partial or complete regressions in four of six tumor lines. There was no apparent cross-resistance to carzelesin in two rhabdomyosarcomas selected for vincristine resistance (Rh12/VCR, Rh18/VCR) or in Rh28/LPAM xenografts selected for primary resistance to the bifunctional alkylating agent melphalan. Interestingly, carzelesin maintained full activity against Rh18/TOPO tumors selected in situ for resistance to topotecan, whereas the colon tumor VRC5/TOPO, selected in a similar manner, was completely resistant to this agent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00685731
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  • 3
    Electronic Resource
    Electronic Resource
    Effects of temperature on the activity of phosphoenolpyruvate carboxylase and on the control of CO2 fixation in Bryophyllum fedtschenkoi (1995)
    Springer
    Planta 196 (1995), S. 375-380 
    Details
    ISSN: 1432-2048
    Keywords: Bryophyllum ; Carbon dioxide fixation ; Malate (apparent K i) ; Phosphoenolpyruvate carboxylase ; Protein phosphorylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The phosphorylation state and the malate sensitivity of phosphoenolpyruvate carboxylase (PEPCase, EC 4.1.1.31) in Bryophyllum fedtschenkoi Hamet et Perrier are altered by changes in the ambient temperature. These effects, in turn alter the in-vivo activity of the enzyme. Low temperature (3 °C or less), stabilizes the phosphorylated form of the enzyme, while high temperature (30 °C) promotes its dephosphorylation. The catalytic activity of the phosphorylated and dephosphorylated forms of PEPCase increases with temperature, but the apparent K i values for malate of both forms of the enzyme decrease. Results of experiments with detached leaves maintained in darkness in normal air indicate that the changes in malate sensitivity and phosphorylation state of PEPCase with temperature are of physiological significance. When the phosphorylated form of PEPCase is stabilized by reducing the temperature of leaves 9 h after transfer to constant darkness at 15 °C, a prolonged period of CO2 fixation follows. When leaves are maintained in constant darkness at 15 °C until CO2 output reaches a low steady-state level and the PEPCase is dephosphorylated, reducing the temperature to 3 °C results in a further period of CO2 fixation even though the phosphorylation state of PEPCase does not change.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00201398
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  • 4
    Electronic Resource
    Electronic Resource
    The role of temperature in the regulation of the circadian rhythm of CO2 fixation in Bryophyllum fedtschenkoi (1995)
    Springer
    Planta 196 (1995), S. 381-386 
    Details
    ISSN: 1432-2048
    Keywords: Bryophyllum ; Circadian rhythm ; Carbon dioxide fixation ; Malate (apparent K i) ; Phosphoenolpyruvate carboxylase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Detached leaves of Bryophyllum fedtschenkoi Hamet et Perrier kept in normal air show a single period of net CO2 fixation on transfer to constant darkness at temperatures in the range 0–25 °C. The duration of this initial fixation period is largely independent of temperature in the range 5–20 °C, but lengthens very markedly at temperatures below 4 °C, and is reduced at temperatures above 25 °C. The onset of net fixation of CO2 on transfer of leaves to constant darkness is immediate at low temperatures, but is delayed as the temperature is increased. The ambient temperature also determines whether or not a circadian rhythm of CO2 exchange occurs. The rhythm begins to appear at about 20 °C, is most evident at 30 °C and becomes less distinct at 35 °C. The occurrence of a distinct circadian rhythm in CO2 output at 30° C in the absence of a detectable rhythm in PEPCase kinase activity shows that the kinase rhythm is not a mandatory requirement for the rhythm of PEPCase activity. However, when it occurs, the kinase rhythm undoubtedly amplifies the PEPCase rhythm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00201399
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  • 5
    Electronic Resource
    Electronic Resource
    Arginine catabolism in Aphanocapsa 6308 (1978)
    Springer
    Archives of microbiology 118 (1978), S. 1-6 
    Details
    ISSN: 1432-072X
    Keywords: Arginine catabolism ; Arginine dihydrolase pathway ; Cyanobacteria ; Aphanocapsa 6308 ; Arginase ; Urease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The catabolic products of arginine metabolism were observed in Aphanocapsa 6308, a unicellular cyanobacterium, by thin layer chromatography of growth media, by limiting growth conditions, and by enzymatic analysis. Of the organic, nitrogenous compounds examined, only arginine supported growth in CO2-free media. The excretion of ornithine at a concentration level greater than citrulline suggested the existence in Aphanocapsa 6308 of the arginine dihydrolase pathway which produced ornithine, CO2, NH4, + adenosine 5′-triphosphate. Its existence was confirmed by enzymatic analysis. Although cells could not grow on urea as a sole carbon source a very active urease and subsequently an arginase were also demonstrated, indicating that Aphanocapsa can metabolize arginine via the arginase pathway. The level of enzymes for both pathways indicates a lack of genetic control. It is suggested that the arginase pathway provides only nitrogen for the cells whereas the arginine dihydrolase pathway provides not only nitrogen, but also CO2 and adenosine 5′-triphosphate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00406066
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  • 6
    Electronic Resource
    Electronic Resource
    Variations in short term products of inorganic carbon fixation in exponential and stationary phase cultures of Aphanocapsa 6308 (1978)
    Springer
    Archives of microbiology 116 (1978), S. 231-234 
    Details
    ISSN: 1432-072X
    Keywords: Cyanobacteria ; Aphanocapsa 6308 ; Inorganic carbon fixation ; C4 photosynthesis ; C3 photosynthesis ; Carbonate fixation ; Bicarbonate fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Aphanocapsa 6308 metabolizes both NaHCO3 and Na2CO3. The short term incorporation (5-s) metabolic pattern and the patterns of incorporation of bicarbonate for exponential versus stationary phase cultures differ, however. Cells were equilibrated for 10 min in air and distilled water prior to injection of either NaH14CO3 at pH 8.0, or Na2 14CO3 at pH 11.0. Hot ethanol extracts were analyzed via paper chromatography and autoradiography for products of CO2 fixation. At 5 s, malate (51.5%) predominates slightly as a primary bicarbonate fixation product over 3-phosphoglycerate (40.3%); 3-phosphoglycerate is the primary product of carbonate fixation. At 60 s, the carbonate and bicarbonate labelling patterns are similar. Cells in stationary phase fix in 5 s a greater proportion of bicarbonate into malate (36% vs. 14% for 3-phosphoglycerate) than do cells in exponential growth. Likewise, 60 s incorporations show a large amount of bicarbonate fixed into aspartate (30.9%) in stationary phase cells over that of exponential phase (11.6%). These data suggest an operative C4 pathway for purposes not related to carbohydrate synthesis but rather as compensation for the incomplete tricarboxylic acid cycle in cyanobacteria. The enhancement of both aspartate fixation and CO2 fixation into citrulline in stationary phase correlates with an increase in cyanophycin granule production which requires both aspartate and arginine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00417844
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  • 7
    Electronic Resource
    Electronic Resource
    The new generation of L. C. columns; A critical evaluation of their systems compatibility and performance (1985)
    Springer
    Chromatographia 20 (1985), S. 335-342 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; External variance determinations ; Column and system compatibility ; Microbore and fast LC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The demand for faster, more economic and convenient high-efficiency LC analyses has led to the development of microbore and fast columns. However, to utilize their benefits, the low column dispersions produced by these new technologies necessitate low external variances in the total system. This paper describes the determination of the external variance of microbore, fast and conventional LC systems by a column method. Compatibility with the relevant column technologies is evaluated by a method involving the comparison of the external and column dispersions. Direct comparison of chromatograms of an 8-component mixture, on a set of columns of various diameters and lengths, shows the relative speed, economy and sensitivity obtainable in practice. The problem of reduced sample loadability is considered and the practical solution of peak compression illustrated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02269058
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  • 8
    Electronic Resource
    Electronic Resource
    Folding in vitro of bovine pancreatic trypsin inhibitor in the presence of proteins of the endoplasmic reticulum (1992)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 14 (1992), S. 10-15 
    Details
    ISSN: 0887-3585
    Keywords: protein disulfide isomerase ; disulfide bonds ; protein folding ; chaperones ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The rate of folding and disulfide bond formation in reduced BPTI were measured in vitro in the presence and absence of total protein from the endoplasmic reticulum. The rates were increased substantially by the endoplasmic reticulum proteins, but only to the extent expected from the known content and activity of protein-disulfide-isomerase. No effects of added ATP or Ca2+ were observed, even though protein-disulfide-isomerase blinds Ca2+ tightly. © 1992 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340140104
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  • 9
    Electronic Resource
    Electronic Resource
    Evaluation of a complete HPLC solvent optimization system involving piece-wise quadratic modelling (1990)
    Springer
    Chromatographia 29 (1990), S. 79-89 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Solven optimization ; Piecewise quadratic modelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Interpretive methods are accepted to give the best possible results for selectivity optimization in HPLC. However the methods are very complex, and most work so far has been detailed academic studies. This paper describes an evaluation of a complete integrated system incorporating peak labelling, modelling of retention behaviour and calculation of response surfaces, with particular emphasis on the retention modelling. The peak labelling section has been discussed previously. A piece-wise quadratic function is investigated for the modelling of retention times across an isoeluotropic plane to effect selectivity optimization in HPLC. This requires 10 data-points on the isoeluotropic plane. The predicted global optimum and local optima are evaluated by comparison of calculated and experimental retention data, for a nine component sample. Seven interstitial points, distributed across the whole plane between the data-points, are similarly evaluated for a related sample. The typical error (in retention time) is less than 2%, often 1%, and the maximum error is 4.2%. At the global optimum the error was found be less than 1.3% for all 9 peaks.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02261144
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  • 10
    Electronic Resource
    Electronic Resource
    Determination of cellular rate distributions in microbial cell populations: Feeding rates of ciliated protozoa (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 284-294 
    Details
    ISSN: 0006-3592
    Keywords: ingestion rate distribution ; population balance ; state properties ; rate properties ; flow cytometry ; particle uptake model ; Poisson process model ; Tetrahymena pyriformis ; suspension feeding ; filter feeding ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A novel procedure is proposed for determining distributions of rate properties and correlations of rate with state properties of microbial cell populations. The procedure is novel in that it uses transient data, and thus, it does not require that the population be in balanced growth, although it requires that the population structure does not change during the short transient experiment. The procedure is applied to populations of the ciliated protozoan Tetrahymena to determine ingestion rate variability. The number of ingested microspheres per cell and the single-cell protein content - an indicator of cell size - were directly determined with dual-color flow cytometry. The proposed technique revealed the correlation pattern of the particle ingestion rate with cell size. In particular, ingestion rate was found to be positively correlated with cell size for the smaller feeding cells and to be uncorrelated with size for the larger cells. Using the fact that particle uptake from dilute particle suspensions is a Poisson random process, we determined that the coefficient of variation of the distribution of ingestion rates within the feeding population is about 50%. It was concluded that the dynamics of particle ingestion can be accurately described only if it is realized that particle ingestion rates are distributed. © 1993 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260420304
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