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 793 records · Page 44Linked to original sources
PubMed2005

Probing p53 biological functions through the use of genetically engineered mouse models.

The p53 tumor suppressor gene is rendered dysfunctional in the majority of human cancers. To model the effects of p53 dysfunction in an experimentally manipulable organismal context, genetically engineered inbred mice have been the models of choice. Transgenic and knock-out technologies have been utilized to generate an array of different p53 germ line alterations. As expected, many (though not all) of the mutant p53 mouse models are susceptible to enhanced spontaneous and carcinogen-induced tumors of a variety of types. A number of different variables affect the incidence and spectrum of tumors in p53 mutant mice. These include strain background, the nature of the p53 mutation, the presence of wild-type p53 (in addition to mutant p53), exposure to physical and chemical mutagens, or introduction of other cancer-associated genes into the mutant p53 background. In addition to their role in furthering our understanding of the mechanisms of cancer initiation and progression, these models have led to unexpected insights into p53 function in embryogenesis and aging. With the development of ever more sophisticated methods for manipulating the mouse genome, new p53 models are on the horizon, which should deliver advances that will provide not only important mechanistic insights but also discoveries of great clinical relevance.

Animals↗
PubMed2006

Cause and effect considerations in diagnostic pathology and pathology phenotyping of genetically engineered mice (GEM).

Over the next several decades, biology is embarking on its most ambitious project yet: to annotate the human genome functionally, prioritizing and focusing on those genes relevant to development and disease. Model systems are fundamental prerequisites for this task, and genetically engineered mice (GEM) are by far the most accessible mammalian system because of their anatomical, physiological, and genetic similarity to humans. The scientific utility of GEM has become commonplace since the technology to produce them was established in the early 1980s. Conceptually, however, an efficiently coordinated high-throughput approach that permits correlation between newly discovered genes, functional properties of their protein products, and biological relevance of these products as drug targets has yet to be established. The discipline of veterinary anatomical pathology (hereafter referred to as pathology) is not immune to this requirement for evolution and adaptation, and to address relationships and tissue consequences between tens of thousands of genes and their cognate proteins, novel interdisciplinary technologies and approaches must emerge. Although many of the techniques of pathology are well established, in the context of pathology's contribution to functional annotation of the genome, several conceptually important and unresolved issues remain to be addressed. While an ever-increasing arsenal of genetic and molecular tool-sets are available to evaluate and understand the function of genes and their pathophysiological mechanisms, pathology will continue to play an essential role in confirming cause and effect relationships of gene function in development and disease. This role will continue to be dependent on keen observation, a systematic but disciplined approach, expert knowledge of strain-dependent anatomical differences and incidental lesions, and relevant tissue-based evidence. Miniaturization and high-throughput adaptation of these methods must also continue so that they can complement parallel phenotyping efforts, provide pathology-based data in pace with concurrent phenotyping efforts, and continue to find new utility in the collective effort of functional annotation.

Animals↗
PubMed1993

A bleeding model in rabbits demonstrate fresh clot selectivity for a genetically engineered variant of tissue-type plasminogen activator and for streptokinase.

The way in which three thrombolytic agents, tissue-type plasminogen activator (t-PA), streptokinase (SK) and a genetically engineered variant of t-PA composed of the second kringle and the protease domain (K2P), cause the dissolution of haemostatic plugs of differing ages was investigated in a novel rabbit model. Standardized incisions were made on the rabbit ear and the wounds were left to heal for 0.5 h or 24 h, before the thrombolytic agents were infused. In the absence of heparin, t-PA showed little discrimination between clots of different ages (36% and 28% lysis of the 0.5 h and 24 h wounds, respectively). In contrast, K2P and SK showed a pronounced fresh clot selectivity since they were significantly more effective in lysing fresh clots than old ones (68% and 4% lysis for K2P and 72% and 36% for SK, respectively). In the presence of heparin the potency of t-PA on fresh clots was considerably increased whilst the effect on old clots was not affected, a fresh clot selectivity for t-PA (64% lysis of fresh clots, 24% lysis of old clots) was thus effected. Heparin did not significantly affect the fresh clot selectivity of K2P or SK, although lysis of old clots was increased (from 4% to 36%) when it was given together with K2P. Furthermore, heparin did not affect the time to onset of bleeding nor was the bleeding time prolonged by its addition. The bleeding time observed for t-PA (20-25 min) was markedly shorter than that found for K2P or SK (40-50 min).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2003

Large-scale production of genetically engineered CYP3A4 in E. coli: application of a jarfermenter.

To produce a large amount of CYP3A4, we applied a jarfermenter (ABLE, BMJ-PI or BMS-PI) to culture the genetically engineered E. coli cells harboring CYP3A4 along with NADPH-cytochrome P450 reductase (OR). The jarfermenter is a stirred bacterial culture vessel in which the pH, the dissolved oxygen (DO) and the temperature of a culture medium can be controlled. The expression of CYP3A4 in E. coli cells in the 500 mL of culture medium contained in the BMJ-PI (1 L vessel) (JFM-1) was examined by altering the parameters mentioned above. The highest expression of CYP3A4 in E. coli cells was attained when cultured at pH 6.0, at 30 degrees C under the DO of 0.1 ppm. The incubation was performed 18 hr after the addition of 1.5 mM isopropyl beta-D(-)-thiogalactopyranoside. The expression levels of CYP3A4 and the OR in the membrane fraction of E. coli cells were 267 nmol/L culture and 552 units/L culture, respectively. The CYP3A4 level was about three times higher than that obtained by incubation in a 500 mL flask (100 mL of medium) (84 nmol/L culture). The testosterone 6beta-hydroxylase activity of CYP3A4 expressed in the membrane fraction of E. coli obtained with the JFM-1 was examined. The apparent K(m) and V(max) values were 66.4 microM and 57.8 nmol/min/nmol CYP, respectively. Expecting the mass production of the CYP3A4 by a culture of E. coli, the possibility of a scale up of the culture with the BMS-PI (10 L vessel) (JFM-10) was examined. The optimal culture condition to achieve the highest expression of CYP3A4 with JFM-1 was employed. The expression levels of CYP3A4 and the OR obtained with JFM-1 and JFM-10 were almost equal. The total level of CYP3A4 obtained by using JFM-10 (5 L of medium) was calculated to be about 1.4 mumol. Based on these results, we confirm that the jarfermenter is a useful tool to produce large amounts of CYP3A4.

Journal Article↗
PubMed1987

[Special conditions for the cultivation of genetically engineered microorganisms].

Using recombinant strains recently the cultivation of microorganisms for biotechnological purposes has reached a qualitative new level. With respect to the optimization of such cultivation processes appropriate variations of genetical, physiological and biochemical parameters will be necessary. This review summarizes trends of construction of vectors and problems of correlations between hosts and vectors with regard to their application in discontinuous and continuous bioreactor-procedures.

Bacteria↗
PubMed1991

Monitoring a genetically engineered bacterium in a freshwater environment by rapid enzymatic amplification of a synthetic DNA "number-plate".

In order to set up a sensitive and reliable detection method to monitor environmentally released genetically engineered microorganisms (GEMs) a 72-bp, double-stranded DNA fragment has been built by annealing and ligating four synthetic oligonucleotides. Binding sites for two 20-mer oligonucleotides are situated inside the DNA fragment, flanking the centre. Into the central part of the construction a 30-nucleotide identification sequence has been fitted. Thanks to the presence of the two oligonucleotide binding sites, the synthetic construction ("number-plate") can be submitted to enzymatic amplification using the polymerase chain reaction (PCR), thus enabling the identification system to take advantage of the outstanding sensitivity of this technique. When released into a freshwater microcosm, cells of Pseudomonas putida carrying a "number-plated" chromosome could be easily and rapidly detected merely by submitting boiled cell sediments to PCR amplification.

Base Sequence↗