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 253 records · Page 14Linked to original sources
PubMed1992

Chilling sensitivity of Arabidopsis thaliana with genetically engineered membrane lipids.

Upon transfer of a genetically engineered Escherichia coli gene for glycerol-3-phosphate acyltransferase (plsB) to Arabidopsis thaliana (L.) Heynh., the gene is transcribed and translated into an enzymatically active polypeptide. This leads to an alteration in fatty acid composition of membrane lipids. From these alterations it is evident that the enzyme is located mainly inside the plastids. The amount of saturated fatty acids in plastidial membrane lipids increased. In particular, the fraction of high-temperature melting species of phosphatidylglycerol is elevated. These molecules are thought to play a crucial role in determining chilling sensitivity of plants. An increase in sensitivity could be observed in the transgenic plants during recultivation after chilling treatment. Implications for the hypothesis of phosphatidylglycerol-determined chilling sensitivity are discussed.

Arabidopsis↗
PubMed1993

A prototype stable RNA identification cassette for monitoring plasmids of genetically engineered microorganisms.

A prototype stable RNA identification cassette for monitoring genetically engineered plasmids carried by strains of Escherichia coli has been developed. The cassette consists of a Vibrio proteolyticus 5S ribosomal RNA (rRNA) gene surrounded by promoters and terminators from the rrnB operon of Escherischia coli. The identifier RNA is expressed and successfully processed so that approximately 30% of the 5S rRNA isolated from either whole cells or 70S ribosomes is of the V. proteolyticus type. Cells carrying the identifier are readily detectable by hybridization. Accurate measurements show that the identification cassette has little effect on fitness compared to a strain containing an analogous plasmid carrying wild type E. coli 5S rRNA, and the V. proteolyticus 5S rRNA gene is not inactivated after prolonged growth. These results demonstrate the feasibility of developing small standardized identification cassettes that can utilize already existing highly sensitive rRNA detection methods. Cassettes of this type could in principle be incorporated into either the engineered regions of recombinant plasmids or their hosts.

Base Sequence↗
PubMed2000

Comparison of skin prick test with serially diluted wild-type and genetically engineered recombinant Der f2.

BACKGROUND: C8/119S, a genetically engineered less allergenic mutant of group II allergen (Der f2) of house dust mite, Dermatophagoidesfarinae, was constructed in order to reduce the risk of anaphylactic reactions of allergen specific immunotherapy. OBJECTIVE: To further evaluate, with a larger number of mite-allergic patients, the safety of C8/119S for the treatments of humans. METHOD: We tested the dose-dependent responses of 20 mite-allergic volunteers to a skin prick test with C8/119S and wild-type recombinant Der f2 and compared the biologic potentials of these allergens to induce type I allergic reactions. In a separate experiment, we compared IgE binding capacities to C8/119S and to wild-type recombinant Der f2 in individual sera from 34 mite-allergic donors. RESULTS: The concentration of C8/119S needed to induce positive skin prick test (SPT) reaction was at least 100 times more than that of recombinant Der f2 in 95% of the volunteers tested. Consistent with this result, IgE binding data showed that 85% of the mite-allergic donors had little or no detectable IgE bound to C8/119S. Our data also shows that a minority of mite-allergic patients responded in a similar manner to both C8/119S and wild-type recombinant Der f2. CONCLUSION: Our data confirms that C8/119S is much less allergenic and thus can be used safely for immunotherapy of most of mite-allergic patients. Care should still be taken because, in a minority of patients, C8/119S may cause similar type I allergic reactions as does wild-type recombinant Der f2.

Adult↗
PubMed1992

[Biological safety investigations of the production of human insulin by genetically engineered E. coli K-12 cells. 1. Survival capacity of the production strain in the digestive tract of Göttinger miniature swine].

The residence time of genetically engineered Escherichia coli K-12 cells in the digestive tract was tested by feeding Göttinger minipigs 10(10)-10(11) cells of strain W3110iqM15 (pSW3). This strain is a production strain for human insulin and carries the plasmid pSW3 which contains the genes for human insulin. The test strain could be selected as white colonies grown on McConkey ampicillin plates and could be identified by complementation analysis due to its lacZ M15 deletion. The strain could be isolated from the faeces of the animals up to 72 h after feeding, thereafter no cells of the phenotype of the test strain grew on McConkey ampicillin plates. So the production strain for human insulin W3110iqM15 (pSW3) was not able to colonize the digestive tract of the Göttinger minipig. Feeding the genetically engineered E. coli K-12 cells had no influence on the welfare of the animals.

Animal Welfare↗
PubMed1995

Tracking genetically engineered microorganisms in nature.

The past year has seen the continued development of methods for tracking genetically engineered microorganisms in nature, with an emphasis on increased sensitivity, specificity and quantitative ability. In addition, novel methods have been developed for tagging bacteria targeted for environmental release. Nevertheless, the limited number of field trials published to date have primarily relied on conventional monitoring methods, despite the availability of better and theoretically safer methods.

Bacteria↗
PubMed2003

Smart and genetically engineered biomaterials and drug delivery systems.

The design, synthesis, and properties of novel stimuli-sensitive and genetically engineered biomaterials and drug delivery systems are reviewed. Two approaches to their engineering are presented. One approach is to improve the traditional methods of synthesis, as demonstrated by the example of controlled copolymerization of alpha-amino acid N-carboxyanhydrides. The other approach, discussed in more detail, uses genetic engineering methods. The design of hybrid hydrogel systems whose components derive from at least two distinct classes of molecules, e.g., synthetic macromolecules and protein domains, is assessed. The design of self-assembling block copolymers is discussed in detail. Finally, the pharmaceutics related applications of these materials are presented.

Biocompatible Materials↗
PubMed1990

[Directions of an ethic in genetic engineering: evaluation of an ethic for biotechnology].

A fundamentalistic point of view is for the evaluation of genetic engineering inadequate. Using ethics to evaluate the consequences is not valid for gene transfers across species as a morally relevant criterion but is rather the assessment of toxic, pathogenic, and ecological effects of transgenic organisms. A criterion for human genetics is not the inviolability of the human embryo, but social and human tolerance and the consent of the affected.

Animals↗
PubMed1995

[Study on the efficacy of genetically engineered vaccines against hepatitis B for interruption of perinatal transmission].

The infectivity rate of newborn babies who had been borne from HBsAG(+), HBeAg(+) and anti-HBc(+) mothers was very high (85%). 142 babies born in the hospital were divided into three groups, in this study. In the group 1, 57 babies were inoculated with 20 micrograms recombinant DNA vaccinia vaccines against hepatitis B. The injections were given at newborn, 1 month, and 6 months, respectively. In group 2, 41 babies were inoculated with 20 micrograms genetic engineering vaccines against hepatitis B at same time were intervals as group 1. In group 3, 44 newborn babies were inoculated with 10 micrograms as same vaccines as group 2 HBIG plus 1ml (200 U/ml), at same time intervals as group 1. The immune pretection rates of newborn babies in three groups were 88.2%, 85.9% and 100%, respectively. The anti-HBs pasitive conversion rates were 82%, 86% and 98%, respectively. The group 3 was compared with group 1 and 2. Statistical analysis showed the significant differences (P < 0.05). The result showed the immune program of group 3 was superior to that of group 1 and 2, and none of the 44 babies in group 3 were infected. The efficacy of immunization by genetic engineering vaccines were superior to that of blood-derived vaccine. The genetic engineering vaccines against hepatitis B would be more useful for interruption of perinatal transmission of HBV.

Female↗
PubMed2005

Deciphering cancer complexities in genetically engineered mice.

Because the pRb pathway is disrupted in most solid human cancers, we have generated genetically engineered mouse cancer models by inactivating pRb function in several cell types, including astrocytes and mammary, prostate, ovarian, and brain choroid plexus epithelia. In every case, proliferation and apoptosis are acutely induced, predisposing to malignancy. Cell type dictates the pathways involved in tumor progression. In the astrocytoma model, we developed strategies to induce events in the adult brain, either throughout the tissue or focally. Both K-Ras activation and Pten inactivation play significant roles in progression. In the prostate model, adenocarcinoma progression depends on Pten inactivation. However, nonautonomous induction of p53 in the mesenchyme leads to evolution of both compartments, with p53 loss occurring in the mesenchyme. Thus, studies in these models continue to identify key tumorigenesis mechanisms. Furthermore, we are hopeful that the models will provide useful preclinical systems for diagnostic and therapeutic development.

Animals↗
PubMed2001

Genetic engineering within the adult brain: implications for molecular approaches to behavioral neuroscience.

Currently, the most popular technology used to modify the molecular makeup of the nervous system is through germline modifications of early embryos. This allows to construct gene 'knock-ins' (gene overexpression) or 'knock-outs' (gene deletions). This technology leads to gene additions or deletions from the earliest developmental stages. This can potentially lead to compensatory genetic changes. The technology to achieve inducible and cell-type-specific changes in gene expression in transgenic animals has been established. However, it is not yet possible, to reliably turn a particular gene 'on' or 'off' exclusively in adult animals. Alternatively, the use of gene transfer technology in fully mature animals could overcome many of these shortcomings. Gene therapy is the use of nucleic acids as drugs, and uses gene transfer technology to genetically engineer adult animals. Viral and nonviral vectors have been modified to serve as vectors for nucleic acid sequences of interest. Thus, over the last two decades, methods have been developed to deliver particular nucleic acids directly to target tissues. Further technological advances allow delivery of transgenes or antisense mRNAs directly to predetermined cell types, as well as their delivery under the control of inducible promoter elements. Combined transgenic (i.e., germline modifications) and viral vector technology will also be very powerful in allowing the genetic modification of selected neuronal populations in adult animals. In this review, we discuss the potential of gene delivery to the brain to analyze the effect of genetic engineering of particular neuronal groups on behavior, as well as recent developments and applications of newly engineered vector systems to allow transgenesis within nervous structures of adult animals.

Animals↗
PubMed1996

Use of green fluorescent protein to monitor survival of genetically engineered bacteria in aquatic environments.

Many methods for detecting model genetically engineered microorganisms (GEMs) in experimental ecosystems rely on cultivation of introduced cells. In this study, survival of Escherichia coli was monitored with the green fluorescent protein (GFP) gene. This approach allowed enumeration of GEMs by both plating and microscopy. Use of the GFP-marked GEMs revealed that E. coli persisted in stream water at higher densities as determined microscopically than as determined by CFU enumeration. The GFP gene did not negatively impact the fitness of the host strain.

Escherichia coli↗
PubMed2006

Rational strain improvement for enhanced clavulanic acid production by genetic engineering of the glycolytic pathway in Streptomyces clavuligerus.

Clavulanic acid is a potent beta-lactamase inhibitor used to combat resistance to penicillin and cephalosporin antibiotics. There is a demand for high-yielding fermentation strains for industrial production of this valuable product. Clavulanic acid biosynthesis is initiated by the condensation of L-arginine and D-glyceraldehyde-3-phosphate (G3P). To overcome the limited G3P pool and improve clavulanic acid production, we genetically engineered the glycolytic pathway in Streptomyces clavuligerus. Two genes (gap1 and gap2) whose protein products are distinct glyceraldehyde-3-phosphate dehydrogenases (GAPDHs) were inactivated in S. clavuligerus by targeted gene disruption. A doubled production of clavulanic acid was consistently obtained when gap1 was disrupted, and reversed by complementation. Addition of arginine to the cultured mutant further improved clavulanic acid production giving a greater than 2-fold increase over wild type, suggesting that arginine became limiting for biosynthesis. This is the first reported application of genetic engineering to channel precursor flux to improve clavulanic acid production.

Clavulanic Acid↗
PubMed1991

Genetic engineering of Trichoderma to produce strains with novel cellulase profiles.

Genetic engineering has been used to modify the proportion of different cellulases produced by a hypercellulolytic Trichoderma reesei mutant strain. A general expression vector, pAMH110, containing the promoter and terminator sequences of the strongly expressed main cellobiohydrolase 1 (cbh1) gene was used to overexpress a cDNA coding for EGI, the major endoglucanase (1,4,beta-D-glucan glucanohydrolase, EC 3.2.1.4). An in vitro modified cbh1 cDNA, incapable of coding for active enzyme, was used to inactivate the major cellobiohydrolase (1,4-beta-D-glucan cellobiohydrolase, EC 3.2.1.91) gene. In this way, new strains producing elevated amounts of the specific endoglucanase 1 (EGI) and/or lacking the major cellobiohydrolase (CBHI) were produced, and these have been further characterized.

Base Sequence↗
PubMed2005

Survey of genetically engineered mouse models for prostate cancer: analyzing the molecular basis of prostate cancer development, progression, and metastasis.

Genetically engineered mouse models have been generated to study the molecular basis of prostate cancer (PCa) development, progression, and metastasis. Selection of a prostate-specific promoter, such as the probasin (PB) and prostate specific antigen (PSA) promoters, is critical for generating sufficient levels of transgene expression to elicit a phenotypic response. To date, target genes have included growth factors, cell cycle regulators, pro- and anti-apoptotic proteins, steroid hormone and growth factor receptors, oncogenes, tumor suppressors, and homeobox genes. The experimental approaches used to generate these mouse models include overexpression of the transgene, knock-out/knock-in of transgene expression and conditional regulation of expression using Cre/lox technology. This review summarizes the promoters, which have been utilized to create genetically engineered mouse models for PCa. Furthermore, the effects of gene disruption on promoting low- and high-grade intraepithelial neoplasia (LGPIN and HGPIN, respectively), locally invasive carcinoma and metastatic lesions will be discussed. To date, the PB-Cre4 x PTENloxp/loxp model appears to be the only model that represents the entire continuum of prostate adenocarcinoma development, tumor progression, and metastasis, although models that develop prostatic neuroendocrine (NE) cancer can be generated by disrupting one genetic event. Indeed, analysis of bigenic mouse models indicates that two genetic events are generally required for progression from HGPIN to locally invasive adenocarcinoma and that two to five genetic events can promote metastasis to distant sites. Studying the effects of genetic perturbation on PCa biology will increase our understanding of the disease process and potentially provide targets for developing novel therapeutic approaches.

Adenocarcinoma↗
PubMed2006

Phase I, open-label, dose-escalating study of a genetically engineered herpes simplex virus, NV1020, in subjects with metastatic colorectal carcinoma to the liver.

Current regimens of systemic chemotherapy result in only modest lengthening of survival in patients with advanced stage, liver-dominant, metastatic colorectal cancer who have failed first-line chemotherapy. The objective of this study was to investigate the safety and tolerability of NV1020, a replication-competent, attenuated, genetically engineered herpes simplex virus type 1 (HSV-1), in patients with hepatic colorectal metastases refractory to first-line chemotherapy. A phase I, open-label, dose-escalating study of a single 10-min hepatic arterial infusion of NV1020 in four cohorts. Three patients in each cohort received doses of 3 x 10(6), 1 x 10(7), 3 x 10(7), and 1 x 10(8) plaque-forming units. Adverse events were either mild or moderate in severity, and self-limiting. Only three serious adverse events (one transient rise in serum y-glutamyltransferase, one diarrhea, and one leukocytosis) experienced by three patients were considered to be possibly or probably related to NV1020. There were no deaths during the study, and there was no evidence of disseminated herpes infection. Viral presence was detected in only one saliva sample and two serum samples from one asymptomatic patient in the highest dose cohort. In the first week after viral administration only rare and minor increases were noted for tumor necrosis factor-alpha (six samples; three patients; peak, 40 pg/ml), interleukin (IL)-1 (two samples; two patients; peak, 28 pg/ml), and interferon-y (four samples; two subjects; peak, 54 pg/ml). No IL-2 was detected. Mild liver enzyme elevations were self-limiting and not associated with clinical symptoms. We conclude that NV1020, a genetically engineered but replication-competent HSV-1 oncolytic virus, can be safely administered into the hepatic artery without significant effects on normal liver function.

Adult↗
PubMedDate not supplied

The use of genetically engineered cells for assessing CYP2D6-related polymorphic effects.

As an example of advanced testing in the field of metabolism in an industrial environment, the introduction of some novel approaches, including the use of genetically engineered cell lines for assessing CYP 2D6-related polymorphic effects is illustrated. In this paper, it is demonstrated that novel in vitro test systems can be developed by using these genetically engineered cell lines for evaluating the potential risks associated with proprietary drugs (especially if their metabolism depends to a high extent on CYP 2D6). Moreover, it is demonstrated that, by the use of these in vitro methods, issues such as polymorphism, for which no animal models are available, can be assessed in such a way that predictions can be made on adverse effects which, up to now, could only be detected during clinical trials. Through the use of these new biotechnological in vitro metabolism models, clinically relevant data can be obtained for a scientifically-based human risk assessment, and animal use can be reduced.

Animal Testing Alternatives↗
PubMed1998

Genetically engineered vaccines: an overview.

Despite the early success demonstrated with the hepatitis B vaccine, no other recombinant engineered vaccine has been approved for use in humans. It is unlikely that a recombinant vaccine will be developed to replace an existing licensed human vaccine with a proven record of safety and efficacy. This is due to the economic reality of making vaccines for human use. Genetically engineered subunit vaccines are more costly to manufacture than conventional vaccines, since the antigen must be purified to a higher standard than was demanded of older, conventional vaccines. Each vaccine must also be subjected to extensive testing and review by the FDA, as it would be considered a new product. This is costly to a company in terms of both time and money and is unnecessary if a licensed product is already on the market. Although recombinant subunit vaccines hold great promise, they do present some potential limitations. In addition to being less reactogenic, recombinant subunit vaccines have a tendency to be less immunogenic than their conventional counterparts. This can be attributed to these vaccines being held to a higher degree of purity than was traditionally done for an earlier generation of licensed subunit vaccines. Ironically, the contaminants often found in conventional subunit vaccines may have aided in the inflammatory process, which is essential for initiating a vigorous immune response. This potential problem may be overcome by employing one of the many new types of adjuvants that are becoming available for use in humans. Recombinant subunit vaccines may also suffer from being too well-defined, because they are composed of a single antigen. In contrast, conventional vaccines contain trace amounts of other antigens that may aid in conferring an immunity to infectious agents that is more solid than could be provided by a monovalent vaccine. This problem can be minimized, where necessary, by creating recombinant vaccines that are composed of multiple antigens from the same pathogen. These issues are less of a concern with a live attenuated vaccine, since these vaccines are less costly, require fewer steps to manufacture, and elicit long-lived immunity after only a single dose. Unfortunately, live vaccines carry a higher risk of vaccine-induced complications in recipients that make their use in highly developed, litiginous countries unlikely. In lesser developed countries, where the prevalence of disease and the need for effective vaccines outweighs the risk associated with their administration, live vaccines may play an important role in human health. This review has attempted to make the reader aware of some of the current approaches and issues that are associated with the development of these vaccines. Genetically engineered vaccines hold great promise for the future, but the potential of these vaccines to improve human and animal health has yet to be fully realized.

Animals↗