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1

The influence of factors on baculovirus / insect cell system productivity

100%
Olejnik A., Grajek W.
Biotechnologia
|
2003
|
issue 1
158-175
EN
The baculovirus expression vector system (BEVS) is a powerful tool for the heterologous protein production. The productivity of BEVS depends on: insect cell lines and their growth parameters, medium composition, multiplicity of infection (MOI), time of infection (TOI), quality of viral inoculum and scale of cultivation. The factors influencing foreign gene expression level in BEVS ? were the subject of the presented review.
2

Baculovirus in biotechnology

100%
Gozdzicka-Jozefiak A., Olejnik A.
Biotechnologia
|
2002
|
issue 1
71-86
EN
Baculoviruses are a diverse group of large viruses with covalently close double-stranded DNA genomes of 80-200 kilobasepairs (kbp). Baculoviruses are pathogenic for invertebrates, primarily for insects. Baculovirus particles exist in two biochemically and morphologically distinct forms, an extracellular, nonoccluded (NOV), budded virus (BV) and an occluded form (OV), which are known as polyhedral derived viruses (PDV). Baculovirus genes expression is divided into three basic phases: early (E), late (L) and very late (VL). Briefly, these phases correspond biologically to: (E) reprogramming the cell for virus replication, (L) producing BV and (VL) producing OV. The several baculovirus genes are nonessential for virus replication, and their lack in viral genome does not have any effect on forming of infectious virus particles in the tissue culture. Some of the gene expression is driven by very strong late promoters (polyhedrin and p10) and their loci are ideal cloning sites for genes of heterologous proteins. The baculovirus expression vector system is the powerful tool for production of foreign proteins. One of the major advantages of the insect cell/baculovirus system over bacterial and mammalian systems is a very high expression of recombinant proteins, which is in many cases, antigenically, immunogenically and functionally similar to their native counterparts.
3
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Effectiveness of Selected Procedures of Hearing Aid Adaptation - Clinical Cases

100%
Hojan-Jezierska D., Olejnik A.
|
EN
For five patients representing different clinical cases the effectiveness of hearing aids adjusted to the individual hearing impairment and with the electroacoustic parameters established on the basis of different algorithms has been evaluated. The results permitted formulation of the rules optimising the effectiveness of the hearing aid use, especially in speech intelligibility.
4

Biotechnology of insect cell tissue culture

100%
Olejnik A., Grajek W.
Biotechnologia
|
2003
|
issue 1
176-192
EN
The commercial exploitation of the baculovirus expression system for heterologous protein or biopesticides production requires an efficient large-scale cultivation method. This review summarized recent developments concerning the scale-up of insect cell culture and baculovirus gene expression. We described novel bioreactor systems (stirred tank bioreactor, bioreactor airlift and cell-lift, membrane bioreactor), culture modes (batch, fed-batch, continuous) and different strategies used for cell cultivation and baculovirus replication.
5

Neoplastic cell transformation by viruses

81%
Schmidt M., Olejnik A., Gozdzicka-Jozefiak A.
Biotechnologia
|
2002
|
issue 1
87-104
EN
Tumor-inducing viruses occur in several taxonomic groups. All RNA tumor viruses belong to retrovirus family, but the DNA tumor viruses come from several different groups. Their oncogenic potential is associated with their replication strategy, and in a vast majority of cases oncogenic transformation occurs only if the viral life cycle is aborted. The oncogenic phenotype results from discrete changes in the expression of key cellular control genes: oncogenes and tumor suppressor genes. Most often, the retroviruses cause the activation of oncogenes, and DNA tumor viruses usually target tumor suppressor genes.
6

Epithelial cell cultures as a model system to study the transepithelial transport

81%
Grajek W., Olejnik A., Staniaszek K.
Biotechnologia
|
2006
|
issue 2
148-165
EN
Epithelial cell lines are commonly accepted model system to determine intestinal permeability and transepithelial transport. The application of Caco-2 human epithelial cell culture can be used to study bioavailability of drug and food compounds. This culture grows on porous membranes and forms a monolayer of well differentiated cells joined by intracellular tight junctions. This system provides selective barrier to study passive and active transport of different molecules. The Caco-2 cells posses some enzymes and transport systems similar to intestinal epithelium in vivo, however, these proteins are expressed to a lesser extent compared to normal enterocytes. In this paper, the advantages and limitations of Caco-2 model are discussed.
7

Comparative in vitro study on the adhesion of probiotic and pathogenic bacteria to different human intestinal cell lines

61%
Lewandowska M., Olejnik A., Neumann M., Krepulec A., Piotrowska J., Tresiak A., Grajek W.
|
EN
The ability of four strains of Lactobacillus sp. two strains of Bifidobacterium sp. and one strain of Listeria mnocytogenes to adhere to human intestinal cell lines Caco-2, HT-29 and Int 407 was examined. Well-developed monolayers of intestinal cells were obtained when initial concentration of Caco-2 cells was 1 x 104/cm2, HT-29 cells 4.2 x 104/cm2, and Int 407 cells 2 x 104/cm2. The appropriate fetal bovine serum additions for Caco-2, HT-29 and Int 407 were 20%, 10% and 10%, respectively. The reduction of serum addition decreased intestinal cell density and prolonged monolayer development. The highest cell densities in epithelial monolayer were obtained in the Int 407 cell cultures. The yield of bacterial adhesion was strain ? dependent. Significant differences were also observed in bacteria adhesion to individual intestinal cell lines. The best adhesion ability to Caco-2 exhibited Lactobacillus rhamnosus GG and Bifidobacterium bifidum. The highest adhesion to HT-29 line demonstrated B. bifidum and Lactobacillus acidophilus LC1. The adhesion of bacteria to Int 407 was much lower. Significant effect on bacteria adhesion has their cell density being in contact with intestinal monolayer. The adherence of Listeria monocytogenes to Caco-2 and HT-29 was very low in the range of 0.2% and 6.0%, respectively.
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