Search PubMed⌕ Search

Biomedical subjects

A Bank

Publications and source records attributed to A Bank.

At least 127 records · Page 7Linked to original sources
PubMed1981

Isolation and characterization of cloned DNA: the delta and beta globin genes in homozygous beta + thalassemia.

We have isolated and characterized a clone of human DNA from a patient with beta+ thalassemia containing the entire delta and beta structural genes and their flanking sequences. Partial Eco RI digestion of spleen DNA was used to obtain 15 to 20 kilobase (kb) pieces of human DNA that were then ligated to charon 4A lambda phage DNA. The 8 x 10(5) recombinants obtained were grown and screened for their content of beta gene sequences. Four positive clones were found, and one (beta T1-1) has been extensively analyzed. Subclones containing the entire beta gene and the large beta intervening sequence (IVS 2) have been isolated in the plasmid pBR 322. The fragments generated by restriction enzyme digestion in these subclones have been compared to those in similar subclones from normal beta genes. No differences have been found indication no significant rearrangements of deletions of the delta and beta genes. With the enzymes used, 11.2% of IVS 2 have been compared, and thus far no differences between the thalassemic and normal genes have been detected. The 24 enzymes used include Hph I, which recognizes the 5' end of IVS 2, and AIu I that cleaves at the 3' end. Thus, there appears to be conservation of nucleotide sequences at the ends of IVS 2 in this beta + thalassemia patient, although RNA metabolism studies suggest a possible defect in RNA processing.

Adult↗
PubMed1980

The molecular basis of disorders of human hemoglobin synthesis.

The structure and organization of the human globin genes at the nucleotide level has been established by restriction endonuclease digestion of cellular DNA, and by the isolation and purification of these genes in phage vectors. With this approach it has been possible to define alterations at the DNA level resulting in a group of inherited diseases of man known as the thalassemia syndromes, and related disorders. Combined with other known genetic and biochemical data, these studies provide a framework for understanding the pathogenesis of these disorders at the molecular level.

Base Sequence↗
PubMed1980

A new effective four-drug combination of CCNU (1-[2-chloroethyl]-3-cyclohexyl-1-nitrosourea) (NSC-79038), vinblastine, prednisone, and procarbazine for the treatment of advanced Hodgkin's disease.

Five hundred and sixty-six patients with either Stage III or IV Hodgkin's disease were prospectively randomized to test whether CCNU and/or vinblastine are more effective than mechlorethamine and/or vincristine with procarbazine and prednisone. The combination of CCNU, vinblastine, procarbazine, and prednisone (CVPP) was shown to be a highly effective program with a complete response frequency of 69%. The use of CCNU as part of the induction program was also shown to be the most significant determinant of prolonged remissions (P = .025). Reduced vomiting and neurotoxicity, as well as the oral administration, were the chief advantages of the CVPP as compared with MOPP. These factors resulted in improved patient and physician compliance. The MVPP regimen was also shown to be a highly effective regimen with a complete response frequency of 73% in patients without prior exposure to chemotherapy. However, the induction regimens containing vinblastine were associated with a significantly higher frequency of fatal hematopoietic toxicities than the induction regimens containing vincristine (P = .05). This higher frequency was almost exclusively seen in the elderly or in patients previously treated with both chemotherapy and radiotherapy. At this time, the remission durations maintained by vinblastine with periodic reinforcement are longer when compared with vinblastine maintenance alone (P = .06), but there is no corresponding increase in survival.

Adult↗
PubMed1980

Disorders of human hemoglobin.

Studies of the human hemoglobin system have provided new insights into the regulation of expression of a group of linked human genes, the gamma-delta-beta-globin gene complex in man. In particular, the thalassemia syndromes and related disorders of man are inherited anemias that provide mutations for the study of the regulation of globin gene expression. New methods, including restriction enzyme analysis and cloning of cellular DNA, have made it feasible to define more precisely the structure and organization of the globin genes in cellular DNA. Deletions of specific globin gene fragments have already been found in certain of these disorders and have been applied in prenatal diagnosis.

Chromosome Aberrations↗
PubMed1980

The organization of the gamma-delta-beta gene complex in normal and thalassemia cells.

Restriction enzyme digestion analysis and direct human globin gene cloning have permitted analysis of the physical arrangement of nucleotide sequences within and surrounding the human globin genes. With these methods it has been shown that the linear arrangement 5' to 3' of the globin genes is G gamma-A gamma-delta-beta. The G gamma and A gamma genes are separated by about 3.5 kilobases (kb), while the A gamma and delta genes are 15 kb apart, and the delta and beta 6.5 kb apart. Each of these genes contains a large intervening sequence (IVS) of approximately 1 kb in precisely the same position between condons 104 and 105. In addition, each of these genes has a small IVS between codons 30 and 31. In homozygous delta beta thalassemia DNA, there is deletion of all of the normal delta and beta gene fragments. However, a new fragment 4.2 kb in size containing the 5' end of the delta globin gene is retained. Retention of this fragment in delta beta thalassemia, but not in HPFH is consistent with a role for sequences in this region for limiting gamma globin gene expression. Studies to date suggest that the beta + and beta 0 thalassemias will be due to a heterogeneous group of DNA defects affecting either beta globin gene transcription or beta mRNA processing. In most cases of beta + and beta 0 thalassemia DNA analyzed, there is no detectable deletion of beta or delta genes. In three India beta 0 patients, deletion of the 3' end of the beta gene has been found. Analysis of cloned beta globin genes from a patient with beta + thalasseia shows differences from normal in the fragments generated by restriction enzymes which cut frequently. Whether these differences are responsible for the defect in thalassemia or are polymorphisms unrelated to thalassemia remains to be determined.

Base Sequence↗
PubMed1979

Isolation and characterization of cloned human fetal globin genes.

Three clones containing both the human G gamma and A gamma globlin genes have been isolated and characterized from a library of DNA fragments generated by partial Eco RI digestion of cellular DNA using charon 4A phage as vector. Two of the clones (NY 2 and 3) are identical and have an insert of 14.0 kb. The third clone (NY 1) has a 15.4 kb insert by virtue of an extra 1.4 kb Eco RI fragment at its 5' most end. This clone also has a Kpn I site not present in the other two suggesting it is the product of the gamma gene on the opposite chromosome. Restriction analysis of the three clones indicates that the G gamma and A gamma genes are linked on a single continuous piece of DNA and are separated by 3.5 kb and each contains at least one large intervening sequence of 0.85 kg between the Bam HI and Eco RI sites. These findings in cloned DNA provide direct evidence for linkage and organization of the gamma genes in man.

Base Sequence↗
PubMed1979

A comparative study of a BCNU containing 4-drug program versus MOPP versus 3-drug combinations in advanced Hodgkin's disease: a cooperative study by the Cancer and Leukemia Group B.

A prospective randomized trial by CALGB examined the relative value of four chemotherapy regimens in 537 patients with stage III B and IV Hodgkin's disease. A new combination BOPP, derived by substitution of BCNU for nitrogen mustard in the MOPP regimen, was compared to MOPP and to two 3-drug regimens, derived by removing the procarbazine in BOPP (BOP) or removing the alkylating agent (OPP). The 4-drug programs gave significantly higher frequency of complete remissions (BOPP 67%, MOPP 63%) than the 3-drug regimens (BOP 40%, OPP 42%), and significantly longer duration of remission and survival. BOPP had a therapeutic activity equal to MOPP, and was accompanied by less toxicity. After 6 cycles of induction chemotherapy, responding patients, both CR and PR, were continued on maintenance chemotherapy for 3 years. No significant difference in relapse rate was demonstrated following maintenance treatment with either vinblastine, chlorambucil, or chlorambucil plus monthly vincristine + prednisone doses. Nor could a reinforcement phase late in the maintenance program be shown to influence the relapse rate. The median survival for all patients entered on the 4-drug programs was 5 years, while the median has not yet been reached at 6 years for those patients, who obtained CR.

Adult↗
PubMed1979

Defects in DNA and globin messenger RNA in homozygotes for hemoglobin Lepore.

Globin messenger RNA (mRNA) isolated from three patients homozygous for hemoglobin Lepore is shown to have a marked reduction of the amount of beta-like globin mRNA (Lepore-globin mRNA sequences) compared with alpha-globin mRNA by molecular hybridization. The relative amounts of alpha- and Lepore mRNA are similar to the amounts of alpha- and Lepore globin synthesized in intact cells and by isolated mRNA in a cell-free system. It is also demonstrated that Lepore-globin mRNA can completely hybridize to full-length or nearly full-length beta-globin specific complementary DNA and protect it from nuclease digestion, indicating close homology between the delta-mRNA sequences present in Lepore mRNA and the beta-complementary-DNA probe. We have also quantitated the numbers of beta-like globin gene sequences in genomic Lepore DNA by molecular hybridization and demonstrated a reduction in their number consistent with the Lepore gene being a delta beta-gene fusion product.

Adolescent↗
PubMed1979

Heterogeneity of DNA fragments associated with the sickle-globin gene.

We have examined the genetic polymorphism previously reported to be associated with the sickle-cell (beta s) gene. The polymorphism involves an alteration of the DNA sequence 3' to the beta-globin gene as detected with the restriction endonuclease, Hpa I. In normal individuals, the beta-globin gene is contained within a DNA fragment of 7.6 kilobases (kb), whereas 87% of individuals with sickle-cell anemia have been reported to have the beta s-gene associated with a 13.0-kb Hpa I fragment. We have studied this polymorphism in 31 New York Black individuals homozygous for sickle-cell anemia to ascertain its genetic and biochemical significance and to evaluate its potential use in the prenatal diagnosis of sickle-cell disease. Our results show only a 58% association of the beta s-gene and the 13.0-kb Hpa I fragment, as well as the presence of additional variants involving the Hpa I site. In addition, the 13.0-kb fragment is also found associated with the beta c- and beta A-genes. Thus, the Hpa I polymorphism probably represents a change in DNA not specifically associated with the beta s-gene, and appears to antedate the beta s-and beta c-mutations.

Anemia, Sickle Cell↗
PubMed1978

Regulation of differentiation in normal and transformed erythroid cells.

Studies are described employing two erythropoietic systems to elucidate regulatory mechanisms that control both normal erythropoiesis and erythroid differentiation of transformed hemopoietic precursors. Evidence is provided suggesting that normal erythroid cell precursors require erythropoietin as a growth factor that regulates the number of precursors capable of differentiating. Murine erythroleukemia cells proliferate without need of erythropoietin; they show a variable, generally low, rate of spontaneous differentiation and a brisk rate of erythropoiesis in response to a variety of chemical agents. Present studies suggest that these chemical inducers initiate a series of events including cell surface related changes, alterations in cell cycle kinetics, and modifications of chromatin and DNA structure which result in the irreversible commitment of these leukemia cells to erythroid differentiation and the synthesis of red-cell-specific products.

Cell Cycle↗
PubMed1978

Quantitation of human globin chain synthesis by cellulose acetate electrophoresis.

We have developed a method for the separation and quantitation of human alpha-, beta-, and gamma-globins utilizing cellulose acetate electrophoresis. The relative rates of synthesis of globin chains in reticulocytes in peripheral blood is determined by: (i) incubating intact cells with [35S]methionine; (ii) preparing globin from the hemolysates; (iii) performing electrophoresis of the globin on cellulose acetate strips; and (iv) autoradiography or direct determination of the radioactivity incorporated into each globin chain. The method is simple and rapid, requires only small amounts of hemolysate (30 micrograms of globin), and provides excellent resolution and reproducible quantitation of alpha-, beta A-, beta S-, and gamma-globin chains for up to 24 peripheral blood samples at one time. Measurements by this method in patients with thalassemia variants and sickle-cell disorders correlate well with analysis of the same samples by carboxymethyl cellulose chromatography. This methodology may permit more widespread analysis of globin synthesis in the thalassemia syndromes and may also be useful in the analysis of globins synthesized from human globin mRNA in cell-free systems.

Anemia, Hemolytic, Autoimmune↗