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At least 1,261 records · Page 70Linked to original sources
PubMed2002

Genetic engineering in allotransplantation of vascularized organs.

Transplantation offers a unique opportunity for gene transfer into allografts before grafting. After organ retrieval, the cold ischemic period renders organs available for manipulation and gene transfer. Local expression of protective or immunomodulatory molecules within the graft environment offers a better local bioavailability of bioreagents and potentially less systemic side effects. Protection against ischemia-reperfusion injury, acute and/or chronic rejection without significant side effects would be a major breakthrough in transplant research. However, protocols of transfection adapted to the transplant setting and control of gene expression must be clearly evaluated before going to clinical trials. The first part of this review deals with gene transfer techniques into the allograft, emphasizing particular transplant conditions that are encountered and that must be respected when designing protocols for gene transfer experiments. The second part deals with specific therapeutic strategies to protect and prolong allograft survival.

Adenoviridae↗
PubMed1992

Strategies for the genetic manipulation of Saccharomyces cerevisiae.

The budding yeast Saccharomyces cerevisiae is now widely used as a model organism in the study of gene structure, function, and regulation in addition to its more traditional use as a workhorse of the brewing and baking industries. In this article the plethora of methods available for manipulating the genome of S. cerevisiae are reviewed. This will include a discussion of methods for manipulating individual genes and whole chromosomes, and will address both classic genetic and recombinant DNA-based methods. Furthermore, a critical evaluation of the various genetic strategies for genetically manipulating this simple eukaryote will be included, highlighting the requirements of both the new and the more traditional biotechnology industries.

Biotechnology↗
PubMed1995

Production and secretion of proteins by streptomycetes.

Streptomycetes produce a large number of extracellular enzymes as part of their saprophytic mode of life. Their ability to synthesize enzymes as products of their primary metabolism could lead to the production of many proteins of industrial importance. The development of high-yielding expression systems for both homologous and heterologous gene products is of considerable interest. In this article, we review the current knowledge on the various factors that affect the production and secretion of proteins by streptomycetes and try to evaluate the suitability of these bacteria for the large-scale production of proteins of industrial importance.

Amino Acid Sequence↗
PubMed1988

Replacement of Streptomyces hygroscopicus genomic segments with in vitro altered DNA sequences.

We have developed a method for gene replacement in Streptomyces hygroscopicus which permits introduction of an in vitro derived mutation carried on a plasmid into the chromosome. We constructed the plasmid pMSB212 which can replicate in S. hygroscopicus and contains the step5 gene of the bialaphos biosynthetic pathway which was inactivated by a frame-shift mutation caused by filling in the cohesive ends of the EcoR I site in the structural gene. pMSB212 was introduced into a bialaphos producer strain and by protoplast regeneration of the primary thiostrepton-resistant transformants, non-producing mutants, were obtained. Biochemical and genetical analyses indicated that these mutants were specifically blocked by introduction of the frame-shift mutation in the step5 gene on the chromosome. This method will enable us to obtain isogenic mutants of known genes and to identify new genes encoded on a cloned fragment.

Chromosomes, Bacterial↗
PubMed1999

Manipulating mammalian genome by gene targeting.

The development of strategies which allow the inactivation of specific murine genes by homologous recombination in embryonic cells has revolutionized biological science in the last 10 years. A large number of mice carrying genetic lesions, generated by gene targeting technology, has tremendously increased our knowledge in many areas of biology, culminating in the identification of mouse models for human genetic disorders. These findings have been recently complemented by "conditional" gene targeting technology, allowing gene inactivation in a defined tissue and at a specific time point during development or adulthood, thereby extending the sophistication and potential of this technology.

Animals↗
PubMed1997

[Erythropoietin gene cloning and expression in S. cerevisiae].

Mature human erythropoietin gene was amplified from EPO cDNA by PCR methods. The PCR product was cloned into pUC18 plasmid at Sma I site, then precisely engineered into a intermidiate vector pSK43SB which were digested with Hind III, Mung bean nuclease, and Sal I. Then degest pSK43SB-EPO plasmid with EcoR I and Cla I, the EC fragment with an alpha-factor leading sequence, EPO gene and CYC1 terminater were produced. It was then cloned into a typical high efficiency episomal expression vector YEpHC8. Human EPO protein with highly mannose glycosylated was identified by Western blot methods in both secreted and in cells proteins. N-Glycosidase F digested secreted EPO can produce 20,000 EPO without N-glycosylation similar with that produced in cells.

Amino Acid Sequence↗
PubMed1998

Construction of engineering host by non-random method in Saccharomyces cerevisiae.

A yeast engineering host, GJ30, was constructed by a non-random method. GJ30 derivated from wild type yeast have leu2- and ura3- deficients which can be used as selection markers. The PCR analysis showed that the homologous recombinations occurred in the leu2 and ura3 locus of GJ30, respectively. The biological properties (cellular growth density, stability and efficiency for gene expression) of GJ30 were compared with other several yeast stains. The results showed that GJ30 is a suitable host strain for expression of foreign genes.

3-Isopropylmalate Dehydrogenase↗
PubMed1999

Immune considerations in tissue engineering.

This article discusses the interplay between manmade living tissues and nature's given ones. Through a multidisciplinary approach, new strategies are outlined to control early inflammatory biochemical events, cell migration and development, and matrix deposition, all of them directed toward the acellular component of tissue-engineered constructs. The construct's resident nonautologous cells are targeted by cell- and humoral-mediated reactions, and modulatory strategies are applied to arrest rejection. The fate of ex vivo virally transfected, genetically engineered cells also is reviewed.

Biocompatible Materials↗
PubMed2000

Genetically engineered tetravalent single-chain Fv of the pancarcinoma monoclonal antibody CC49: improved biodistribution and potential for therapeutic application.

Failure of radiolabeled monoclonal antibodies (MAbs) in the treatment of solid tumors, for the most part, is a result of undesirable pharmacokinetics that lead to significant radiation exposure of normal tissues and an inadequate delivery of radiation doses to tumors. Using genetic engineering, antitumor MAbs can be optimized for desirable clinical applications. In the present study, we report the generation of a tetravalent single-chain Fv [[sc(Fv)2]2] of the murine MAb CC49 that recognizes the tumor-associated glycoprotein, TAG-72. [Sc(Fv)2]2 was expressed as a secreted soluble protein in Pichia pastoris under the regulation of alcohol oxidase 1 promoter. The in vitro binding properties of the tetravalent construct were analyzed by solid-phase RIA and surface plasmon resonance studies using BIAcore. The binding affinity constant (K(A)) for the [sc(Fv)2]2 and CC49 IgG were similar, i.e., 1.02 x 10(8) M(-1) and 1.14 x 10(8) M(-1), respectively, and were 4-fold higher than its divalent scFv [sc(Fv)2; 2.75 x 10(7) M(-1)]. At 6 h postadministration, the percentage of injected dose accumulated/g of LS-174T colon carcinoma xenografts was 21.3+/-1.3, 9.8+/-1.3, and 17.3+/-1.1 for radioiodinated [sc(Fv)2]2, sc(Fv)2, and IgG, respectively. Pharmacokinetic analysis of blood clearance studies showed the elimination half-life for [sc(Fv)2]2, sc(Fv)2, and IgG as 170, 80, and 330 min, respectively. The gain in avidity resulting from multivalency along with an improved biological half-life makes the tetravalent construct an important reagent for cancer therapy and diagnosis in MAb-based radiopharmaceuticals.

Alcohol Oxidoreductases↗
PubMed2001

Genetically engineered dendritic cell-based cancer vaccines (review).

Dendritic cells (DCs) are the most potent professional antigen-presenting cells with exquisite capacity to interact with T cells and initiate their responses; the antigen-presenting capabilities of DCs make them attractive vehicles for the delivery of therapeutic cancer vaccines. The working hypothesis for utilization of DC-based cancer vaccines is that lack of efficient tumour antigen presentation on mature DCs, which is frequently observed in tumour-bearing individuals, can be bypassed by direct loading of DCs with oncoproteins in vitro, thus ensuring the transfer of immunostimulatory peptides on the respective antigen-presenting molecules. To enhance loading of DCs with oncoproteins in vitro and to increase the efficacy of the vaccines, a variety of genetic manipulations have been proposed and shown to be efficient in experimental tumour models. DCs were transfected either with polynucleotides, DNA or RNA, coding for tumour-associated antigens (TAAs), or with DNA encoding immunostimulatory cytokines and co-stimulatory molecules. The delivery of genes coding for antigenic epitopes or other molecules with a recombinant retrovirus, adenovirus, or poxvirus into dendritic cells has also been used for transduction and therapy. As an alternative method for TAA delivery into DCs, fusion of DCs with tumour cells has been utilized and the hybrid cell-based vaccines have been found to be highly therapeutically active, even in cancer patients. The purpose of this review is to summarize the approaches used for making and utilization of the genetically engineered DC-based cancer vaccines, to evaluate the therapeutic results obtained with the vaccines, and to discuss prospects and limitations of the vaccination.

Animals↗
PubMed2001

Secretion of mouse-metallothionein by engineered E. coli cells in metal-enriched culture media.

Heterologous Escherichia coli expression systems were designed and assayed for the synthesis of functional mouse metallothionein (MT) as a secreted fusion protein. MT secretion was compared among different systems, and the optimum vector/host/medium combination was tested for metal removal. In this case, the Cu content of the medium decreased by up to 34% after growth of recombinant bacteria. The potential use of these genetically-engineered bacteria for water bioremediation is discussed as an alternative to cytoplasmic MT or membrane-bound MT heterologous expression systems.

Animals↗