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  • Female  (3)
  • Male  (3)
  • flow cytometry  (3)
  • linear optimization  (3)
  • 1
    Publication Date: 2007-05-05
    Description: The global endemic of cardiovascular diseases calls for improved risk assessment and treatment. Here, we describe an association between myocardial infarction (MI) and a common sequence variant on chromosome 9p21. This study included a total of 4587 cases and 12,767 controls. The identified variant, adjacent to the tumor suppressor genes CDKN2A and CDKN2B, was associated with the disease with high significance. Approximately 21% of individuals in the population are homozygous for this variant, and their estimated risk of suffering myocardial infarction is 1.64 times as great as that of noncarriers. The corresponding risk is 2.02 times as great for early-onset cases. The population attributable risk is 21% for MI in general and 31% for early-onset cases.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Helgadottir, Anna -- Thorleifsson, Gudmar -- Manolescu, Andrei -- Gretarsdottir, Solveig -- Blondal, Thorarinn -- Jonasdottir, Aslaug -- Jonasdottir, Adalbjorg -- Sigurdsson, Asgeir -- Baker, Adam -- Palsson, Arnar -- Masson, Gisli -- Gudbjartsson, Daniel F -- Magnusson, Kristinn P -- Andersen, Karl -- Levey, Allan I -- Backman, Valgerdur M -- Matthiasdottir, Sigurborg -- Jonsdottir, Thorbjorg -- Palsson, Stefan -- Einarsdottir, Helga -- Gunnarsdottir, Steinunn -- Gylfason, Arnaldur -- Vaccarino, Viola -- Hooper, W Craig -- Reilly, Muredach P -- Granger, Christopher B -- Austin, Harland -- Rader, Daniel J -- Shah, Svati H -- Quyyumi, Arshed A -- Gulcher, Jeffrey R -- Thorgeirsson, Gudmundur -- Thorsteinsdottir, Unnur -- Kong, Augustine -- Stefansson, Kari -- New York, N.Y. -- Science. 2007 Jun 8;316(5830):1491-3. Epub 2007 May 3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉deCODE genetics, Sturlugata 8, IS-101 Reykjavik, Iceland.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17478679" target="_blank"〉PubMed〈/a〉
    Keywords: Age of Onset ; Aged ; Case-Control Studies ; Chromosome Mapping ; Chromosomes, Human, Pair 9/*genetics ; Coronary Artery Disease/genetics ; Female ; Genes, p16 ; *Genetic Predisposition to Disease ; *Genetic Variation ; Genotype ; Haplotypes ; Heterozygote ; Homozygote ; Humans ; Linkage Disequilibrium ; Male ; Middle Aged ; Myocardial Infarction/*genetics ; *Polymorphism, Single Nucleotide ; Risk Factors
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 39 (1992), S. 487-497 
    ISSN: 0006-3592
    Keywords: Photoautotrophic growth ; Chlorelia vulgaris ; oscillations ; autoinhibitor ; flow cytometry ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Sustained oscillations in cell concentration, average per cell DNA content, and average cell size were found in continuous photoautotrophic cultures of Chlorella vulgaris at low dilution rates (0.1/day). The period of oscillation was approximately 10 days. DNA histograms determined by flow cytometry exhibited reproducible pattern through consecutive oscillations. At the maximum cell concentration during an oscillation, the DNA histograms showed that the majority of the cells were not replicating their chromosomes, and most of the culture was comprised of single cells in G0/G1 phase. The cells then initiated DNA replication; however, because of the long generation time, the cell concentration decreased to a minimum, and at the same time the average per cell DNA content reached its maximum value. At this point the cells began to divide, and the cell concentration increased until it reached its maximum value at the beginning of the next oscillation. Calculations based on the supplied nutrients and comparison to biomass generation showed that the oscillatory behavior in continuous photoautotrophic cultures of C. vulgaris was not due to nutrient limitation, but most likely was due to the secretion of compounds that alter cell cycle kinetics. The oscillatory behavior disappeared when the dilution rate was increased to 0.3/day and the culture reached a stable steady state.
    Additional Material: 9 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 38 (1991), S. 821-830 
    ISSN: 0006-3592
    Keywords: hybridoma ; immobilization ; serum ; flow cytometry ; antibody productivity ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effect of serum on cell growth and monoclonal antibody (MAb) productivity was studied in a repeated fedbatch mode using both free-suspended and immobilized S3H5/γ2bA2 hybridoma cells. In the suspension culture, serum influenced the cell growth rate but not the specific MAb productivity. The average specific growth rate of the suspension culture in medium containing 10% serum was approximately 0.99 ± 0.12 day-1 (±standard deviation), while that in medium containing 1% serum was approximately 0.73 ± 0.12 day-1. The specific MAb productivity was almost constant at 3.69 ± 0.57 μg/106 cells/day irrespective of serum concentration reached a maximum at ca. 1.8 × 106 cells/mL of medium in 10% serum medium, and the cell concentration was gradually reduced to 1%. The specific MAb productivity of the immobilized cells was more than three times higher than that of the free-suspended cells. The amount of serum in the medium did not influence the specific MAb production rate of the immobilized cells. The maintenance of high cell concentration and the enhanced specific MAb productivity of the immobilized cell culture resulted in a higher volumetric MAb productivity. In addition, MAb yield in the immobilized cell culture with medium containing 1% serum was 2.2 mg/mL of serum, which was approximately three times higher than that in the suspension culture.
    Additional Material: 11 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 38 (1991), S. 1182-1189 
    ISSN: 0006-3592
    Keywords: photobioreactor ; ultrfiltration ; photoautotrophic ; DNA histograms ; cell cycle ; flow cytometry ; chlorella vulgaris ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A photobioreactor system has been designed, constructed and implemented to achieve high photosynthetic rates in high-density photoautotrophic algal cell suspensions. This unit is designed for efficient oxygen and biomass production rates, and it also can be used for the production of secreted products. A fiber-optic based optical transmission system that is coupled to an internal light distribution system illuminates the culture volume uniformly, at light intensities of 1.7 mW/cm2 over a specific surface area of 3.2 cm2/cm3. Uniform light distribution is achieved throughout the reactor without interfering with the flow pattern required to keep the cells in suspension. An on-line ultrafiltration unit exchanges spent with fresh medium, and its use results in very high cell densities, up to 109 cells/mL [3% (w/v)] for eukaryotic green alga chlorella vulgaris. DNA histograms obtained form flow cytometric analysis reveal that on-line ultrafiltration influences the growth pattern. Prior to ultrafiltration the cells seem to have at a particular point in the cell cycle where they contain multiple chromosomal equivalents. Following ultrafiltration, these cells divide, and the new cells are committed to division so that cell growth resumes. The Prototype photobioreactor system was operated both in batch and in continuous mode for over 2 months. The measured oxygen production rate of 4-6 mmol/L culture h under continuous operation is consistent with the predicted performance of the unit for the provided light intensity.
    Additional Material: 6 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 59-73 
    ISSN: 0006-3592
    Keywords: Escherichia coli ; amino acids ; nucleotides ; biosynthesis ; linear optimization ; metabolic fluxes ; metabolic engineering ; stoichiometry ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Microbial metabolism provides at mechanism for the conversion of substrates into useful biochemicals. Utilization of microbes in industrial processes requires a modification of their natural metabolism in order to increase the efficiency of the desired conversion. Redirection of metabolic fluxes forms the basis of the newly defined field of metabolic engineering. In this study we use a flux balance based approach to study the biosynthesis of the 20 amino acids and 4 nucleotides as biochemical products. These amino acids and nucleotides are primary products of biosynthesis as well as important industrial products and precursors for the production of other biochemicals. The biosynthetic reactions of the bacterium Escherichia coli have been formulated into a metabolic network, and growth has been defined as a balanced drain on the metabolite pools corresponding to the cellular composition. Theoretical limits on the conversion of glucose, glycerol, and acetate substrates to biomass as well as the biochemical products have been computed. The substrate that results in the maximal carbon conversion to a particular product is identified. Criteria have been developed to identify metabolic constraints in the optimal solutions. The constraints of stoichiometry, energy, and redox have been determined in the conversions of glucose, glycerol, and acetate substrates into the biochemicals. Flux distributions corresponding to the maximal production of the biochemicals are presented. The goals of metabolic engineering are the optimal redirection of fluxes from generating biomass toward producing the desired biochemical. Optimal biomass generation is shown to decrease in a piecewise linear manner with increasing product formation. In some cases, synergy is observed between biochemical production and growth, leading to an increased overall carbon conversion. Balanced growth and product formation are important in a bioprocess, particularly for nonsecreted products. © 1993 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 275-285 
    ISSN: 0006-3592
    Keywords: Escherichia coli ; amino acids ; linear optimization ; metabolic fluxes ; metabolic engineering ; culture stability ; oxygen ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The simultaneous growth and product formation in a microbial culture is an important feature of several laboratory, industrial, and environmental bioprocesses. Metabolic burden associated with product formation in these bioprocesses may lead to growth advantage of a nonproducing mutant leading to a loss of the producing population over time. A simple population dynamics model demonstrates the extreme sensitivity of population stability to the engineered productivity of a strain. Here we use flux balance analysis to estimate the effects of the metabolic burden associated with product secretion on optimal growth rates. Comparing the optimal growth rates of the producing and nonproducing strains under a given processing condition allows us to predict the population stability. In order to increase stability of an engineered strain, we determine processing conditions that simultaneously maximize the growth rate of the producing population while minimizing the growth rate of a nonproducing population. Using valine, tryptophan, and lysine production as specific examples, we demonstrate that although an appropriate choice of oxygenation may increase culture longevity more than twofold, total production as governed by economic criterion can be increased by several orders of magnitude. Choice of optimal nutrient and oxygen supply rates to enhance stability is important both for strain screening as well as for culture of engineered strains. Appropriate design of the culture environment can thus be used to enhance the productivity of bioprocesses that use engineered production strains. © 1994 John Wiley & Sons, Inc.
    Additional Material: 11 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 45 (1995), S. 69-79 
    ISSN: 0006-3592
    Keywords: E. coli ; linear optimization ; metabolic fluxes ; stoichiometry ; sensitivity analysis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Stoichiometrically based flux balance models provide a method to quantify the metabolic pathway fluxes within a living cell. Predictions of flux balance models are expected to have applications in pathway engineering as well as in bioprocess design and control. These models utilize optimality principles applied to metabolic pathway stoichiometry along with the metabolic requirements for growth to determine the flux distribution in a metabolic network. A flux balance model has been developed for Escherichia coli W3110 using five experimentally determined strain-specific parameters. In this report, we determine the sensitivity of the predictions of the flux balance model to these five strain-specific parameters. Model predictions are shown to be sensitive to the two parameters describing metabolic capacity, while they are relatively insensitive to the three parameters that describe the metabolic requirements for growth. Thus, when stoichiometrically based models are formulated for additional strains one needs to measure the metabolic capacity (maximum rates of nutrient and oxygen utilization) accurately. Determination of metabolic capacity from batch experiments is relatively easy to perform. On the other hand, the harder to determine maintenance parameters need not be as accurately determined. © 1995 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
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  • 8
    Publication Date: 2008-02-09
    Description: Previous studies have reported that related human couples tend to produce more children than unrelated couples but have been unable to determine whether this difference is biological or stems from socioeconomic variables. Our results, drawn from all known couples of the Icelandic population born between 1800 and 1965, show a significant positive association between kinship and fertility, with the greatest reproductive success observed for couples related at the level of third and fourth cousins. Owing to the relative socioeconomic homogeneity of Icelanders, and the observation of highly significant differences in the fertility of couples separated by very fine intervals of kinship, we conclude that this association is likely to have a biological basis.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Helgason, Agnar -- Palsson, Saebjorn -- Gudbjartsson, Daniel F -- Kristjansson, Thornordur -- Stefansson, Kari -- New York, N.Y. -- Science. 2008 Feb 8;319(5864):813-6. doi: 10.1126/science.1150232.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉deCODE Genetics, Sturlugata 8, 101 Reykjavik, Iceland. agnar@decode.is〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18258915" target="_blank"〉PubMed〈/a〉
    Keywords: Consanguinity ; *Family ; *Family Characteristics ; Female ; *Fertility ; Humans ; Iceland ; Male ; Socioeconomic Factors
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 9
    Publication Date: 2008-02-02
    Description: The genome-wide recombination rate varies between individuals, but the mechanism controlling this variation in humans has remained elusive. A genome-wide search identified sequence variants in the 4p16.3 region correlated with recombination rate in both males and females. These variants are located in the RNF212 gene, a putative ortholog of the ZHP-3 gene that is essential for recombinations and chiasma formation in Caenorhabditis elegans. It is noteworthy that the haplotype formed by two single-nucleotide polymorphisms (SNPs) associated with the highest recombination rate in males is associated with a low recombination rate in females. Consequently, if the frequency of the haplotype changes, the average recombination rate will increase for one sex and decrease for the other, but the sex-averaged recombination rate of the population can stay relatively constant.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kong, Augustine -- Thorleifsson, Gudmar -- Stefansson, Hreinn -- Masson, Gisli -- Helgason, Agnar -- Gudbjartsson, Daniel F -- Jonsdottir, Gudrun M -- Gudjonsson, Sigurjon A -- Sverrisson, Sverrir -- Thorlacius, Theodora -- Jonasdottir, Aslaug -- Hardarson, Gudmundur A -- Palsson, Stefan T -- Frigge, Michael L -- Gulcher, Jeffrey R -- Thorsteinsdottir, Unnur -- Stefansson, Kari -- New York, N.Y. -- Science. 2008 Mar 7;319(5868):1398-401. doi: 10.1126/science.1152422. Epub 2008 Jan 31.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉deCODE Genetics Inc, 101 Reykjavik, Iceland. kong@decode.is〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18239089" target="_blank"〉PubMed〈/a〉
    Keywords: Alleles ; Chromosomes, Human, Pair 4/*genetics ; Fathers ; Female ; *Genome, Human ; Haplotypes ; Humans ; Linkage Disequilibrium ; Male ; Meiosis ; Molecular Sequence Data ; Mothers ; Polymorphism, Single Nucleotide ; *Recombination, Genetic ; Sex Characteristics ; Synaptonemal Complex/metabolism ; Ubiquitin-Protein Ligases/*genetics
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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