Mice, men and sickle cells

Article Abstract:

Sickle cell anemia was first identified in human beings over 30 years ago but very little progress has been made in the treatment of this genetic disease. The condition is caused by defective hemoglobin, the iron-containing pigment in red blood cells, which results in deformed red blood cells that have short life spans and impair normal blood circulation. Patients often experience intense bone pain, organ damage and severe anemia. They are also prone to infection, which is the most frequent cause of death. Disease severity is not predictable; some patients survive with relatively few problems, while others become very ill or die at a young age. A major obstacle in the development of an effective treatment has been the lack of an animal model for testing purposes. An article by Greaves et al. in the January 11, 1990 issue of 'Nature' contains new evidence that the use of a mouse model for sickle cell anemia may be effective. The researchers have identified the dominant control region sequences which border the location of the hemoglobin defect in humans. Researchers were successful in developing two "transgenic" mice with high levels of the defective human hemoglobin in their red blood cells. These cells showed sickle cell characteristics when extracted and analyzed, but when hematological tests were performed, the results were not distinguishable from those obtained from normal mice. The results of these experiments are encouraging, but a workable animal model for sickle cell anemia has still not been developed. (Consumer Summary produced by Reliance Medical Information, Inc.)

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A transgenic mouse model of sickle cell disorder

Article Abstract:

Sickle cell anemia is a genetic disease that results from defective or mutant hemoglobin caused by the substitution of one amino acid for another (valine for glutamic acid) at position six in the beta-globin chain. This causes the formation of deformed and inefficient red blood cells that have short life spans and impair normal blood circulation. Patients often experience intense bone pain, organ damage, severe anemia and frequent infection. This condition was first identified in human beings over 30 years ago, but very little progress has been made in the treatment of this disorder. A major obstacle in the development of an effective treatment has been the lack of an animal model for testing purposes. In a recent experiment the normal expression of hemoglobin was genetically modified and a hybrid product was created which incorporated the sickle cell hemoglobin. The sickle cell hemoglobin mutation was achieved in three mice (now called "transgenic" mice). The newly synthesized sickle cell hemoglobin was present in 10 to 80 percent concentrations of total blood hemoglobin. These mice produced the same sickle-shaped erythrocytes (red blood cells) that characterize sickle cell anemia. Some characteristic symptoms were also observed. This provides the first model for live animal experimentation. One potential use of this model would be to develop antisickling agents that may serve as potential treatments for this disease. (Consumer Summary produced by Reliance Medical Information, Inc.)

Erythrocytes, Red blood cells

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Transcription complex stability and chromatin dynamics in vivo

Article Abstract:

The identification of the transcriptional activity of individual genes in the nucleus aides the analysis of developmental transcriptional regulation and chromatin dynamics. Transcriptional regulation is more successfully observed using in situ hybridization compared to conventional in situ analysis. This technique reveals a dynamic interaction process between long-range chromatin (LCR) hypersensitive sites and distant regulatory sequences. Gamma and beta-globin genes are transcribed alternately with the LCR activating each gene sequentially rather than concurrently.

Chromatin, Genetic regulation, Genetic transcription, Transcription (Genetics)

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