Ändra sökning
Avgränsa sökresultatet
1 - 8 av 8
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1. Calles, Karin
    et al.
    Svensson, Ingrid
    Lindskog, Eva
    KTH, Skolan för bioteknologi (BIO), Bioprocessteknik.
    Häggström, Lena
    Effects of conditioned medium factors and passage number on Sf9 cell physiology and productivity2006Ingår i: Biotechnology progress (Print), ISSN 8756-7938, E-ISSN 1520-6033, Vol. 22, nr 2, s. 394-400Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effects of conditioned medium (CM) and passage number on Spodoptera frugiperda Sf9 cell physiology and productivity have been studied. Low passage (LP) cells at passages 20-45 were compared to high passage (HP) cells at passages > 100. Addition of 20% CM or 10 kDa filtrated CM to LP cells promoted growth. LP cells passed a switch in growth kinetics, characterized by a shorter lag phase and a higher growth rate, after 30-40 passages. After this point, CM lost its stimulating effect on proliferation. HP cells displayed a still shorter lag phase and reached the maximum cell density 24-48 earlier than LP cells. HP cells also exhibited higher specific productivity of recombinant protein compared to LP cells, when infected with baculovirus during the initial 48 h of culture. The specific productivity of LP cells was decreased by 30-50% by addition of 20% CM or 10 kDa filtrated CM, whereas addition of CM to cells having passed the switch in growth kinetics had no negative effect on productivity. Cell cycle analysis showed that a large proportion of HP cells, >60%, was transiently arrested in G2/M after inoculation. In LP cultures this proportion was lower, 40-45%, and addition of CM decreased the arrested population further. This correlated to the cell size, the HP cells being the largest: HP cells > LP > LP + 20% CM > LP + 20% 10 kDa filtrated CM. Since the degree of synchronization in G2/M correlated to the productivity, yeastolate limitation was used to achieve 85% G2/M synchronized cells. In this culture the specific productivity was maintained during a prolonged production phase and a 69% higher volumetric yield was obtained. The results suggest that a decreasing degree of synchronization during the course of culture partly explains the cell-density-dependent drop in productivity in Sf9 cells.

  • 2.
    Clincke, Marie-Francoise
    et al.
    KTH, Skolan för bioteknologi (BIO), Bioprocessteknik.
    Mölleryd, Carin
    KTH, Skolan för bioteknologi (BIO), Bioprocessteknik.
    Samani, Puneeth K
    KTH, Skolan för bioteknologi (BIO), Bioprocessteknik.
    Zhang, Ye
    KTH, Skolan för bioteknologi (BIO), Bioprocessteknik.
    Lindskog, Eva
    GE Healthcare, Uppsala, Sweden.
    Walsh, Kieron
    GE Healthcare, Westborough, MA, USA.
    Chotteau, Veronique
    KTH, Skolan för bioteknologi (BIO), Bioprocessteknik.
    Perfusion of an IgG producing CHO cell line at very high cell density by ATF or by TFF in WAVE Bioreactor™2011Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Perfusion of an IgG producing CHO cell line was performed in a WAVE Bioreactor™ using either Alternating Tangential Flow or Tangential Flow Filtration. The properties and performances obtained with both filtration systems were compared. Very high cell densities were achieved and could be stably maintained. Then the cell density could be significantly further increased showing the capacity of the system set-up.

  • 3.
    Clincke, Marie-Francoise
    et al.
    KTH, Skolan för bioteknologi (BIO), Bioprocessteknik.
    Mölleryd, Carin
    KTH, Skolan för bioteknologi (BIO), Bioprocessteknik.
    Samani, Puneeth K.
    KTH, Skolan för bioteknologi (BIO), Bioprocessteknik.
    Zhang, Ye
    KTH, Skolan för bioteknologi (BIO), Bioprocessteknik.
    Lindskog, Eva
    GE Healthcare, Uppsala, Sweden.
    Walsh, Kieron
    GE Healthcare, Westborough, MA, USA.
    Chotteau, Veronique
    KTH, Skolan för bioteknologi (BIO), Bioprocessteknik.
    Perfusion of an IgG producing CHO cell line at very high cell density by ATF or by TFF in WAVE Bioreactor™2011Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Perfusion of an IgG producing CHO cell line was performed in a WAVE Bioreactor™ using either Alternating Tangential Flow or Tangential Flow Filtration. The properties and performances obtained in this bioreactor with both filtration systems were studied.

    • Very high cell densities were achieved and could be stably maintained at high viability indicating of a healthy process suitable for instance for efficient cell banking.

    Cell density could be significantly further increased showing the capacity of the system set-up.

  • 4.
    Doverskog, Magnus
    et al.
    KTH, Tidigare Institutioner                               , Bioteknologi.
    Bertram, Eva.
    KTH, Tidigare Institutioner                               , Bioteknologi.
    Ljunggren, Jan
    Öhman, Lars
    Sennerstam, Roland
    Häggström, Lena
    KTH, Tidigare Institutioner                               , Bioteknologi.
    Cell cycle progression in serum-free cultures of Sf9 insect cells: Modulation by conditioned medium factors and implications for proliferation and productivity2000Ingår i: Biotechnology progress (Print), ISSN 8756-7938, E-ISSN 1520-6033, Vol. 16, nr 5, s. 837-846Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cell cycle progression was studied in serum-free batch cultures of Spodoptera frugiperda (Sf9) insect cells, and the implications for proliferation and productivity were investigated. Cell cycle dynamics in KBM10 serum-free medium was characterized by an accumulation of 50-70% of the cells in the G(2)/M phase of the cell cycle during the first 24 h after inoculation. Following the cell cycle arrest, the cell population was redistributed into G(1) and in particular into the S phase. Maximum rate of proliferation (mu(N,max)) was reached 24-48 h after the release from cell cycle arrest, coinciding with a minimum distribution of cells in the G(2)/M phase. The following declining mu(N) could be explained by a slow increase in the G(2)/M cell population. However, at approximately 100 h, an abrupt increase in the amount of G(2)/M cells occurred. This switch occurred at about the same time point and cell density, irrespective of medium composition and maximum cell density. An octaploid population evolved from G(2)/M arrested cells, showing the occurrence of endoreplication in this cell line. In addition, conditioned medium factor(s) were found to increase mu(N,max), decrease the time to reach mu(N,max), and decrease the synchronization of cells in G(2)/M during the lag and growth phase. A conditioned medium factor appears to be a small peptide. On basis of these results we suggest that the observed cell cycle dynamics is the result of autoregulatory events occurring at key points during the course of a culture, and that entry into mitosis is the target for regulation. Infecting the Sf9 cells with recombinant baculovirus resulted in a linear increase in volumetric productivity of beta-galactosidase up to 68-75 h of culture. Beyond this point almost no product was formed. Medium renewal at the time of infection could only partly restore the lost hypertrophy and product yield of cultures infected after the transition point. The critical time of infection correlated to the time when the mean;population cell volume had attained a minimum, and this occurred 24 h before the switch into the G(2)/M phase. We suggest that the cell density dependent decrease in productivity ultimately depends on the autoregulatory events leading to G(2)/M cell cycle arrest.

  • 5.
    Lindskog, Eva
    KTH, Skolan för bioteknologi (BIO).
    Physiology and productivity of serum-free Spodoptera frugiperda Sf9 insect cell cultures2006Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The objective of this study was to investigate the mechanisms and factors controlling growth and proliferation in serum-free Spodoptera frugiperda Sf9 cultures as well as the implications of these factors for protein production in the baculovirus expression system.

    The physiology of recently thawed, low passage (Lp) Sf9 cultures, were compared to high passage (Hp) cultures at p>100. Lp cells passed a switch in proliferation kinetics after 30-40 passages, characterized by a shorter lag-phase and an increased maximum specific proliferation rate, µN,max, from 0.03/h to 0.04/h. Conditioned medium (CM), 10 kDa CM filtrate and 10 kDa CM concentrate promoted proliferation of Lp Sf9 cells, but had no effect after the switch. Sf9 cell cycle dynamics were characterized by an initial G2/M arrest, which synchronized the cells and this feature was more pronounced for Hp than for Lp cells. CM addition decreased the initial arrest for Lp cultures, but did not affect Hp cells. Late in the culture, a final G2/M accumulation occurred. An octaploid population emerged during G2/M arrests. Further, a 49 kDa proform and a 39 kDa active form of Sf9 cathepsin L was identified from gelatine zymography of Sf9 CM, on basis of inhibitor profile and substrate range. Removal of procathepsin L during the course of an Sf9 culture had a negative effect on Sf9 proliferation. Procathepsin L was also identified in Trichoplusia ni High five CM. High five CM promoted growth of Sf9 cells, but when procathepsin L was removed no effect was observed. It is suggested that these observations are due to an autocrine system controlling proliferation. One Sf9 mitogen might be a <10 kDa peptide, while the effect of 10 kDa CM concentrate may originate from procathepsin L. A hypothesis is therefore that procathepsin L acts as a mitogen in Sf9 cultures, perhaps in concert with the <10 kDa peptide.

    The volumetric product yield (P) in baculovirus infected Sf9 cells increased linearly up to 68-75 h of culture. Beyond this point almost no product was detected. Medium renewal at infection prolonged the productivity phase until 117 h, but generated only a 10% increase in P. The specific product formation rate (YP/N) was highest at µN,max. YP/N of Lp cells decreased by 30-50% when 20% CM or 10 kDa CM filtrate was added, whereas addition of CM to cells having passed the switch on growth kinetics did not affect productivity. Further, Hp cells exhibited a two-fold higher YP/N than Lp cells, when infected during the initial 48 h of culture. This coincided with a high degree of synchronization. Yeastolate limitation was used to achieve artificial synchronization of an Lp culture, and YP/N could thereby be maintained high during a prolonged time, resulting in a 69% increased P. This suggests that a decreasing degree of synchronization during the course of a culture partly explains the cell-density dependent drop in productivity in Sf9 cells.

    Finally, ~10 kDa gel filtration fractions from Sf9 and High five CM were found to be bactericidal. Exposure of a Bacillus megaterium culture for eight min to an Sf9 CM fraction killed 99% of the population, and 60 min exposure killed 35% of an Escherichia coli population. In both cases cell lysis was observed. B. megaterium incubated in an High five CM fraction lost 97% viability in 40 min. The effect of the High five CM fraction most probably originated from a lysozyme precursor protein, whereas the Sf9 executor remains unknown.

  • 6.
    Lindskog, Eva
    et al.
    KTH, Skolan för bioteknologi (BIO), Bioprocessteknik.
    Eriksson, Ulrika
    Häggström, Lena
    KTH, Skolan för bioteknologi (BIO), Bioprocessteknik.
    Extracellular proteolytic activity innon-infected Sf9 and Trichoplusia ni Hi5 insect cell cultures: Implications for proliferation.Manuskript (preprint) (Övrigt vetenskapligt)
  • 7.
    Lindskog, Eva
    et al.
    KTH, Skolan för bioteknologi (BIO), Bioprocessteknik.
    Svensson, Ingrid
    KTH, Skolan för bioteknologi (BIO), Bioprocessteknik.
    Häggström, Lena
    KTH, Skolan för bioteknologi (BIO), Bioprocessteknik.
    A homologue of cathepsin L identified in conditioned medium from Sf9 insect cells2006Ingår i: Applied Microbiology and Biotechnology, ISSN 0175-7598, E-ISSN 1432-0614, Vol. 71, nr 4, s. 444-449Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Gelatin zymography revealed the presence of proteolytic activity in conditioned medium (CM) from a serum-free, non-infected Spodoptera frugiperda, Sf9 insect cell culture. Two peptidase bands at about 49 and 39 kDa were detected and found to be proform and active form of the same enzyme. The 49-kDa form was visible on zymogram gels in samples of CM taken on days 4 and 5 of an Sf9 culture, while the 39-kDa form was seen on days 6 and 7. On basis of the inhibitor profile and substrate range, the enzyme was identified as an Sf9 homologue of cathepsin L, a papain-like cysteine peptidase. After lowering the pH of Sf9 CM to 3.5, an additional peptidase band at 22 kDa appeared. This peptidase showed the same inhibitor profile, substrate range and optimum pH (5.0) as the 39-kDa form, indicating that Sf9 cathepsin L has two active forms, at 39 and 22 kDa. Addition of the cysteine peptidase inhibitor E-64c to an Sf9 culture inhibited all proteolytic activities of Sf9 cathepsin L but did not influence the proliferation of Sf9 cells.

  • 8.
    Svensson, Ingrid
    et al.
    KTH, Skolan för bioteknologi (BIO).
    Calles, Karin
    KTH, Skolan för bioteknologi (BIO), Bioprocessteknik.
    Lindskog, Eva
    KTH, Skolan för bioteknologi (BIO).
    Henriksson, Hongbin
    KTH, Skolan för bioteknologi (BIO).
    Eriksson, Ulrika
    KTH, Skolan för bioteknologi (BIO).
    Häggström, Lena
    KTH, Skolan för bioteknologi (BIO), Bioprocessteknik.
    Antimicrobial activity of conditioned medium fractions from Spodoptera frugiperda Sf9 and Trichoplusia ni Hi5 insect cells2005Ingår i: Applied Microbiology and Biotechnology, ISSN 0175-7598, E-ISSN 1432-0614, Vol. 69, nr 1, s. 92-98Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Concentrated conditioned medium (CM) fractions from Spodoptera frugiperda Sf9 and Trichoplusia ni cells, eluting from a gel filtration column at around 10 kDa, were found to exhibit strong antibacterial activity against Bacillus megaterium and Escherichia coli. The B. megaterium cells incubated in the CM fraction from Sf9 cells rapidly lost viability: after 8 min the viability had decreased to 0.7%, as compared with the control. Addition of the CM fraction to E. coli cells resulted in a less drastic drop in viability: 65% viability was lost after 60 min of incubation. Further, exposure to the CM fraction caused a substantial leakage of intracellular proteins, as demonstrated by SDS-PAGE analysis. Cell lysis was confirmed by optical density measurements, microscopic investigations and flow cytometry. B. megaterium exposed to a CM fraction from T. ni cells lost 97% of their viability in about 40 min. Ubiquitin, thioredoxin and cyclophilin were identified in the antibacterial fraction from Sf9 cells by mass spectrometry and N-terminal amino acid sequencing. Other proteins in the fraction gave no matches in a database search. Since ubiquitin was shown not to cause the antimicrobial effect and thioredoxin and cyclophilin were likely not involved, the responsible agent may be an unknown protein, not yet registered in databases. The antimicrobial effect of the CM fraction from T. ni cells most probably comes from a lysozyme precursor protein.

1 - 8 av 8
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf