PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Genetic Engineering”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 451 records · Page 25Linked to original sources
PubMed2004

Nanopore formation by self-assembly of the model genetically engineered elastin-like polymer [(VPGVG)2(VPGEG)(VPGVG)2]15.

The self-assembly characteristics of the model genetically engineered elastin-like polymer [(VPGVG)2(VPGEG)(VPGVG)2]15 have been studied in this work. An AFM study of the topology of polymer films deposited from acid and basic solutions on a hydrophobic silicon substrate has been carried out. Under acidic conditions, polymer deposition results in a flat surface with no particular topological features. However, from basic solutions, polymer deposition clearly shows an aperiodic pattern of nanopores ( approximately 70 nm width and separated about 150 nm). This dramatic dependence of film topology on pH is explained in terms of the different polarity of the free gamma-carboxyl group of the glutamic acid. In the carboxylate form, this moiety shows a markedly higher polarity than the rest of the polymer domains and the substrate itself. Under these conditions, the charged carboxylates impede hydrophobic contact with their surroundings, which is the predominant assembly pathway for this type of polymer. The charged domains, along with their hydration sphere, are then segregated from the hydrophobic surroundings giving rise to nanopores.

Biomimetic Materials↗
PubMed1998

Rapid method for the detection of genetically engineered microorganisms by polymerase chain reaction from soil and sediments.

A rapid and sensitive method for the detection of genetically engineered microorganisms in soil and sediments has been devised by in vitro amplification of the target DNAs by a polymerase chain reaction. A cloned catechol 2,3-dioxygenase gene located on the recombinant plasmid pOH101 was transferred to Pseudomonas putida MMB2442 by triparental crossing and used as a target organism. For the polymerase chain reaction from soil and sediment samples, the template DNA was released from a 100-mg soil sample. Bacterial seeded soil samples were washed with Tris-EDTA buffer (pH 8.0) and treated with a detergent lysis solution at 100 degrees C. After addition of 1% polyvinylpolypyrrolidine solution, the samples were boiled for 5 min. Supernatant containing nucleic acid was purified with a PCR purification kit. The purified DNA was subjected to polymerase chain reaction, using two specific primers designed for the amplification of catechol 2,3-dioxygenase gene sequences. The detection limit was 10(2) cells per gram of soil. This method is rapid and obviates the need for lengthy DNA purification from soil samples.

Catechol 2,3-Dioxygenase↗
PubMed2004

Compound 800, a natural product isolated from genetically engineered Pseudomonas: proposed structure, reactivity, and putative relation to heme d1.

Genetically engineered strains of Escherichia coli and Pseudomonas aeruginosa were prepared harboring the gene cluster nirFDLGH from Pseudomonas stutzeri substrain ZoBell on a high copy plasmid. These genes have been previously implicated as being essential for the biosynthesis of heme d(1), the prosthetic group of dissimilatory nitrite reductases in anaerobic, denitryfying bacteria. Tetrapyrroles detectable at steady-state levels were identified from both organisms, and cell-free extracts from each were also used to transform uroporphyrinogen in vitro. E. coli does not naturally produce d(1), and the engineered strain failed to produce d(1) or any tetrapyrrole foreign to E. coli. Therefore, while nirFDLGHmay be necessary for d(1) biosynthesis, it is not sufficient. In the denitrifier P. aeruginosa, the results were more positive. The presence of the plasmid led to increased levels of d(1). In addition, a previously unidentified tetrapyrrole was detected. This compound was characterized by visible absorption spectroscopy, infrared spectroscopy, X-ray photoelectron spectroscopy, mass spectrometry, and NMR, and a tentative structure was proposed for this compound. The tetrapyrrole has structural features similar to sirohydrochlorin (as precorrin-2 or sirotetrahydrochlorin, a known intermediate of d(1)) and d(1) itself. The most unusual substituents are epoxide and sulfoxide moieties. When this tetrapyrrole was treated with strong mineral acid and heat, it was converted into natural d(1).

Enzymes↗
PubMed1991

Functional and immunological characterization of SIV envelope glycoprotein produced in genetically engineered mammalian cells.

Retroviral envelope glycoproteins interact with cell receptors and are targets for antiviral immune responses in infected hosts. Macaque simian immunodeficiency virus (SIVmac) is a T-lymphocytopathic lentivirus which causes an AIDS-like disease in rhesus macaques. The envelope gene of SIVmac encodes a precursor glycoprotein (gp160) which is cleaved into an external domain (gp130) and a transmembrane domain (gp32). To investigate the functional and immunological properties of the SIV external envelope glycoprotein, we have used genetically engineered mammalian cells to produce recombinant gp130 (rgp130). The rgp130 has the appropriate molecular weight, is glycosylated, and has native conformation as determined by binding to the cell receptor for SIV, the CD4 antigen. Rhesus macaques immunized with purified rgp130 formulated in muramyl dipeptide adjuvant generated high titers of antienvelope antibodies. Antibodies from these macaques were tested for in vitro virus neutralization; very low or undetectable levels of neutralization were observed. In contrast, neutralizing antibodies were readily detected in sera from goats immunized with rgp130. With respect to cell-mediated immunity, proliferative responses to rgp130 were demonstrated in peripheral blood monocyte cells (PBMC) from macaques immunized with the recombinant glycoprotein as well as in PBMC from SIV-infected animals. These results show that rgp130 is functional and immunogenic; the potential of rgp130 for protective immunization remains to be determined.

Animals↗
PubMed2003

Genetic engineering and autonomous agency.

In this paper I argue that the genetic manipulation of sexual orientation at the embryo stage could have a detrimental effect on the subsequent person's later capacity for autonomous agency. By focussing on an example of sexist oppression I show that the norms and expectations expressed with this type of genetic manipulation can threaten the development of autonomous agency and the kind of social environment that makes its exercise likely.

Embryo, Mammalian↗
PubMed2004

What have genetically engineered mice taught us about ischemic injury?

Stroke, is the third leading cause of death and disability in the Western world. Stroke refers to set of ischemic conditions resulting from the occlusion or hemorrhage of blood vessels supplying the brain. Loss of blood flow to the brain results in neuronal injury due to both oxygen and nutrient deprivation and the activation of injurious signal cascades. Ultimately cerebral ischemia results in death and dysfunction of brain cells, and neurological deficits that reflect the location and size of the compromised brain area. Injury due to ischemic stroke occurs by a highly choreographed series of complex spatial and temporal events that evolve over hours to days. These events involve complex interactions between fundamental cell injury mechanisms including excitotoxicity and ionic imbalance, oxidative and nitrosative stress, apoptotic-like cell death and inflammatory responses. Genetically engineered mice have been valuable tools to probe putative mechanisms of neuronal death and uncover potential strategies that might render neurons resistant to ischemic injury. Findings from experimental stroke studies in genetically engineered animals are discussed.

Animals↗
PubMed1985

Application of monoclonal antibodies and genetically-engineered hybrid B-subunit proteins to the analysis of the cholera/coli enterotoxin family.

Single amino acid substitutions, introduced by genetic engineering, significantly modify the behavior of the B-subunits of the cholera/coli enterotoxin family in SDS-PAGE and also markedly affect the reactivity of the proteins with mouse hybridoma-derived monoclonal antibodies raised against H-LT. The results indicate that single amino acids play an important role in defining epitopes in these proteins.

Amino Acid Sequence↗
PubMed1989

Human cell models for genetic engineering.

Technological advances made in molecular biology and culture of human and other mammalian cells in vitro have increased the ability to introduce functional genes into a variety of cell types. Subgenomic components of both DNA and RNA viruses are used as the eukaryotic components of many recombinant DNA vector constructs which are used for transfection either by a variety of methods to facilitate DNA uptake or as virions. This paper reviews some of the factors involved in expression, persistence, and recombination of the introduced genes. Also considered are the use of DNA transfection models to study human cancer or other diseases, the current status of gene therapy, and the use of human cells to produce biologicals. The need to better develop well-characterized human cell culture models from multiple organ sites and various cell types is a recurrent theme for all of these applications, including the role that such cells will play in understanding the functions for genes which will be identified in the human genome cloning project. With continued study and a better understanding of pathophysiology at the cellular and molecular levels should come the logical next step of adding genetically engineered human cells to the repertoire of acceptable biomedical technologies.

Cells, Cultured↗
PubMed1994

Survival and respiratory activity of genetically engineered Pseudomonas spp. exposed to antimicrobial agents in broth and soil.

The effectiveness of seven chemical disinfectants were tested against genetically engineered Pseudomonas spp. under optimal growth conditions. Each chemical was tested to determine how quickly 10(8) cells/ml Pseudomonas fluorescens C5t (containing Bacillus thuringiensis endotoxin gene) were killed in King's B broth at 30 degrees C. The minimal bactericidal concentrations (MBC) for calcium hypochlorite, benzalkonium chloride, Germiphene and Spectrum Clear Bath were 0.06% (w/v), 0.01% (w/v), 0.08% (v/v) and 0.044 (v/v), respectively. Virocidin X and CanLab Neutral did not kill P. fluorescens C5t at concentrations up to 20% (v/v). Baxter Bacdown was ineffective as a killing agent at concentrations up to 10% (v/v). These agents were also tested on P. aureofaciens RNL11 (lacZY), P. putida strains PaW8 and PaW340 (containing the plasmid pLV1013 encoding the xylE gene) and P. aeruginosa UG2L (lacZY and luxAB). All strains were killed by similar disinfectant concentrations with the exception of P. aeruginosa UG2L. The MBCs for this strain were double the MBCs for P. fluorescens C5t with all disinfectants used except for Spectrum Clear Bath, which was similar. Oxygen consumption and carbon dioxide evolution were used to assess the activity of P. fluorescens C5t inoculated in non-sterile soil in the presence of antimicrobial agents. Concentrations chosen were 0.1 and 1.0% (w/v) calcium hypochlorite, 0.01 and 0.1% (w/v) benzalkonium chloride, 0.1 and 1.0% (v/v) Germiphene and 0.1 and 1.0% (v/v) Spectrum Clear Bath. Over a 15-day period, the antimicrobial agents did not reduce respiratory activity of P. fluorescens C5t and indigenous soil micro-organisms.(ABSTRACT TRUNCATED AT 250 WORDS)

Containment of Biohazards↗
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↗
PubMed2006

Genetic engineering and therapy for inherited and acquired cardiomyopathies.

The cardiac myofilaments consist of a highly ordered assembly of proteins that collectively generate force in a calcium-dependent manner. Defects in myofilament function and its regulation have been implicated in various forms of acquired and inherited human heart disease. For example, during cardiac ischemia, cardiac myocyte contractile performance is dramatically downregulated due in part to a reduced sensitivity of the myofilaments to calcium under acidic pH conditions. Over the last several years, the thin filament regulatory protein, troponin I, has been identified as an important mediator of this response. Mutations in troponin I and other sarcomere genes are also linked to several distinct inherited cardiomyopathic phenotypes, including hypertrophic, dilated, and restrictive cardiomyopathies. With the cardiac sarcomere emerging as a central player for such a diverse array of human heart diseases, genetic-based strategies that target the myofilament will likely have broad therapeutic potential. The development of safe vector systems for efficient gene delivery will be a critical hurdle to overcome before these types of therapies can be successfully applied. Nonetheless, studies focusing on the principles of acute genetic engineering of the sarcomere hold value as they lay the essential foundation on which to build potential gene-based therapies for heart disease.

Acidosis↗
PubMed1996

[Generation of genetic engineering anti-idiotypic antibody against OC125 monoclonal antibody of ovarian carcinoma].

OBJECTIVES: To amplify and express the variable region genes of murine derived anti-idiotypic monoclonal antibody and to develop a new kind of ovarian carcinoma vaccine. METHODS: mRNA was prepared from murine hybridoma which produces anti-idiotypic antibody against OC125. The heavy and light chain variable region genes (VH and VL) were amplified by polymerase chain reaction (PCR), joined by DNA linker fragments to form single chain FV gene (ScFv), and were ligated into phage mid vector, pCANTAB 5E. The recombinant vector was induced into competent E. coli TG1 cells. The phage displayed recombinant antibodies were detected and identified by enzyme-linked immunosorbent assay (ELISA). RESULTS: The VH, VL and ScFv genes were 340 bp, 325 bp and 750 bp respectively. Some of the transformed clones expressed engineered anti-idiotypic antibodies, which could specifically bind to the original antibody (OC125). CONCLUSIONS: Genetic engineering anti-idiotypic antibody against OC125 monoclonal antibody was successfully generated. Clinical application of anti-idiotypic antibody to immunotherapy and to prevention of ovarian carcinoma may be studied.

Animals↗
PubMedDate not supplied

Improved erythromycin production in a genetically engineered industrial strain of Saccharopolyspora erythraea.

An industrial erythromycin production strain of Saccharopolyspora erythraea spp. was used to demonstrate that careful genetic engineering can significantly improve productivity. The chromosomally integrated Vitreoscilla hemoglobin gene (vhb) was shown to enhance the final titer of erythromycin by some 70% compared to the original S. erythraea spp. Overall, specific erythromycin yields were about 2.5 g of erythromycin/g of total protein for S. erythraea::vhb but <1 for the S. erythraea spp. The maximum rates of biosynthesis were 57.5 mg of erythromycin/(L/h) and 24.3 mg/(L/h) for the recombinant strain S. erythraea::vhb and S. erythraea spp., respectively. Overall space-time yield was 100% higher for the S. erythraea::vhb fermentation (1.1 g of erythromycin/(L/day)) than for the S. erythraea spp. fermentation (0. 56 g of erythromycin/(L/day)). The genetic stability of the recombinant strain was high, and no selective pressure was needed throughout the cultivations. Expression of functional Vitreoscilla hemoglobin throughout the cultivations was verified by CO difference spectrum assays.

Bacterial Proteins↗
PubMed1998

Generation of CD8+ and CD4+ T-cell response to dendritic cells genetically engineered to express the MART-1/Melan-A gene.

Both CD8+ and CD4+ T cells have demonstrated roles in antitumor immune response in many animal tumor systems. In many human tumor systems, although abundant literature exists on the evidence of tumor antigen-specific CD8+ CTL response, only limited information is available on tumor antigen-specific CD4+ T-cell response. Using the MART-1/Melan-A (MART-1) antigen system as a prototype human tumor-associated antigen (TAA)- and dendritic cell (DC)-based MART-1 antigen presentation system (i.e., DCs transduced with an adenoviral vector-based construct carrying the MART-1 gene), we explored, in vitro, the feasibility of generating both CD8+ and CD4+ T-cell responses in the same individual. Here, we show that autologous DCs from both HLA-A2-positive melanoma patients and normal healthy individuals that are transduced with an adenoviral vector containing the MART-1 antigen are capable of inducing both MART-1-specific CD8+ and CD4+ T cells in in vitro coculture. After several rounds of stimulation, both the CD4+ and CD8+ T cells synthesized IFN-gamma when they were specifically stimulated. The CD8+ T cells generated in such cocultures also recognized the MART-1(27-35) peptide, AAGIGILTV, in 4-h cytotoxicity assays. These observations, therefore, suggest that Th1-type responses can be generated, in vitro, by stimulation with DCs that are genetically modified to express a TAA. Although the outcome of this type of genetically engineered DC-based stimulation may vary from system to system, this type of in vitro antigen presentation may be very useful in more comprehensive analyses of CD4+ T-cell response to defined TAAs, and such genetically engineered autologous DCs might be better candidates to serve as surrogate cancer vaccines.

Antigens, Neoplasm↗
PubMed1993

Contamination of genetically engineered CHO-cells by epizootic haemorrhagic disease virus (EHDV).

The characterization of a contaminating virus which was detected in genetically-engineered Chinese hamster ovary (CHO) cells during the production of biologicals is described in the present paper. Under electron microscopy, the contaminating virus had a morphology resembling that of an orbivirus. The relationship was confirmed by nucleic acid analysis which showed a RNA segment pattern characteristic of orbiviruses. With an immunoperoxidase staining of monolayer cells and through sero-neutralization tests the virus was identified as being identical to Epizootic Haemorrhagic Disease Virus (EHDV), isolate 318 (untyped) from Bahrain. Potential sources of the contaminating virus and feasible procedures to avoid adventitous virus infections in cell cultures are discussed.

Animals↗