Alpha zero-thalassemia due to recombination between the alpha 1-globin gene and an AluI repeat

A form of alpha zero-thalassemia found in subjects of Mediterranean origin has been analyzed by gene mapping and DNA sequencing. Homozygotes have the hemoglobin Bart's hydrops fetalis syndrome, while compound heterozygotes for this defect and alpha+-thalassemia have hemoglobin H disease. It results from a deletion that removes 20.5 kilobases of DNA from within the alpha-globin gene cluster. Sequence data from the regions adjacent to the breakpoint indicate that the recombination event that caused this deletion occurred between the alpha 1-gene and an unusual AluI sequence located between the embryonic zeta genes.     

The p53 gene in pediatric therapy-related leukemia and myelodysplasia

We investigated the frequency of p53 mutations in 19 pediatric cases of therapy-related leukemia or myelodysplastic syndrome. Eleven children presented with acute myeloid leukemia, one with mixed-lineage leukemia, two with acute lymphoblastic leukemia, and five with myelodysplasia at times ranging from 11 months to 9 years after a primary cancer diagnosis. The primary cancers, which included 11 solid tumors and eight leukemias, were treated with various combinations of DNA topoisomerase II inhibitors, alkylating agents, or irradiation. Leukemic or myelodysplastic marrows were screened for possible mutations by single-strand conformation polymorphism (SSCP) analysis of p53 exons 4 to 8. The only observed mutation was an inherited 2- basepair deletion at codon 209 in exon 6 that would shift the open reading frame, create a premature termination codon, and foreshorten the resultant protein. Prior therapy in this patient included DNA topoisomerase II inhibitors, alkylating agents, and irradiation. The secondary leukemia presented as myelodysplasia with monosomies of chromosomes 5 and 7 and abnormalities of chromosome 17. Although the primary cancer was an embryonal rhabdomyosarcoma and there was a family history of cancer, the case did not fulfill the clinical criteria for Li-Fraumeni syndrome. This study suggests that germline p53 mutations may predispose some children to therapy-related leukemia and myelodysplasia, but that p53 mutations otherwise are infrequent in this setting.     

Recombinant immunotoxins containing anti-Tac(Fv) and derivatives of Pseudomonas exotoxin produce complete regression in mice of an interleukin-2 receptor-expressing human carcinoma

Anti-Tac(Fv)-PE40 is a recombinant single-chain immunotoxin composed of the variable domains of the monoclonal antibody anti-Tac, which binds to the p55 subunit of the interleukin-2 receptor (IL-2R), and a truncated form of Pseudomonas exotoxin (PE), which does not bind to the PE receptor (Chaudhary et al, Nature 339:394, 1989). Whereas its cytotoxic activity toward autoimmune and malignant target cells has been established, its efficacy in vivo remains unknown. To establish an animal model, we produced ATAC-4 cells by transfecting the gene encoding the low-affinity IL-2R (p55) into A431 epidermoid carcinoma cells. ATAC-4 cells contained low-affinity IL-2Rs (2 x 10(5)/cell) and formed tumors in nude mice. In tissue culture, protein synthesis in ATAC-4 cells was inhibited 50% (IC50) at 0.06 ng/mL (0.9 pmol/L) of anti-Tac(Fv)-PE40. IC50s for the derivatives anti-Tac(Fv)-PE38, which is missing PE amino acids 365-380, and anti-Tac(Fv)-PE38KDEL, which contains the same deletion plus the KDEL carboxyl terminus, were 0.04 and 0.025 ng/mL, respectively. All the agents produced complete tumor regressions in ATAC-4 tumor-bearing mice and anti-Tac(Fv)-PE38KDEL had significant antitumor activity at 1% of the LD50. The dose limiting toxicity of anti-Tac(Fv)-PE38KDEL was from hemorrhagic liver necrosis, which was observed at approximately 55% of the LD50.     

Expression of a homologously recombined erythopoietin-SV40 T antigen fusion gene in mouse liver: evidence for erythropoietin production by Ito cells

We have obtained transgenic mice in which an erythropoietin-SV40 virus T antigen fusion gene is homologously recombined into the native Epo locus. This gene is expressed in a tissue-specific manner closely resembling that of the native Epo gene. Immunohistochemical detection of SV40 T antigen has been used to characterize the hepatic cell populations expressing the transgene. In mice stimulated by anaemia or hypobaric hypoxia, SV40 T antigen was demonstrated in two liver cell populations: a subset of hepatocytes and a nonparenchymal cell type. Immunohistochemical and ultrastructural characterization of these cells by light and electron microscopy showed the nonparenchymal cell type to be the Ito cells, which lie in a persinusoidal position within the space of Disse. We therefore conclude that Ito cells are the nonhepatocytic source of liver Epo production. These cells show many similarities to the Epo-producing fibroblastoid interstitial cells of the kidney.     

Interaction of hemoglobin E and pyrimidine 5' nucleotidase deficiency

A Bangladeshi family is described in which the genes for both hemoglobin E (Hb E) and pyrimidine 5' nucleotidase deficiency are segregating. An individual homozygous for both these conditions has a severe hemolytic anemia, whereas family members who are homozygous for Hb E are asymptomatic and those homozygous for pyrimidine 5' nucleotidase deficiency have the mild hemolytic anemia that is characteristic of this disorder. Globin-chain synthesis experiments have shown that the mechanism underlying the interaction between these two genotypes is a marked decrease in the stability of Hb E in pyrimidine 5' nucleotidase-deficient red blood cells (RBCs). It has also been found that in the enzyme-deficient RBCs in which Hb E is highly unstable, free alpha-chains, though not beta E-chains, acoumulate on the membrane. In view of the increasing evidence that the hemolysis associated with pyrimidine 5' nucleotidase deficiency results not only from an increase in the level of erythrocyte pyrimidines, but also from inhibition of the hexose monophosphate shunt activity in young erythrocytes, it is likely that the marked instability of Hb E in the enzyme-deficient cells results from oxidant damage acting on a mildly unstable Hb variant. These observations may have important implications for the better understanding of the pathophysiology of Hb E/beta-thalassemia, globally the commonest important form of thalassemia.     

Treatment of acute nonlymphocytic leukemia: use of anthracycline- cytosine arabinoside induction therapy and comparison of two maintenance regimens

Patients with acute nonlymphocytic leukemia were given remission induction therapy consisting of cytosine arabinoside and an anthracycline. Those patients who experienced complete remission received two courses of consolidation therapy and were randomized to receive maintenance therapy consisting of either daily chemotherapy with reinforcements every 3 mo or reinforcement therapy only every 6 wk. The overall complete remission rate was 66%, with 80% complete remission for previously untreated patients less than 60 yr of age who did not have a prior history of malignancy. Remission durations were the same for patients treated with both maintenance regimens. The major determinant for successful remission induction therapy was patient age, with older patients frequently succumbing to intercurrent infection. Documented leukemic cell resistance to the therapy employed was only rarely encountered. Once remission was achieved, age was no longer a determinant of patient survival, since duration of remission was independent of age. Remission durations were directly related to leukemic cell retention of cytosine arabinoside triphosphate. Hence therapy for acute nonlymphocytic leukemia can be divided into two separate areas: remission induction and remission maintenance.     

A K-ras oncogene increases resistance to sulindac-induced apoptosis in rat enterocytes

BACKGROUND & AIMS: Mutations of c-K-ras occur commonly in colonic neoplasms. The aim of this study was to determine how c-K-ras mutations alter the responses to the chemopreventive agent sulindac. METHODS: The parental rat intestinal cell line IEC-18 and c-K-ras-transformed derivatives were treated with sulindac sulfide. Cell cycle distribution was determined by flow-cytometric analysis (fluorescence-activated cell sorter), apoptosis by DNA fragmentation (laddering), flow cytometry, and microscopy, and changes in gene expression by immunoblotting. RESULTS: Sulindac sulfide inhibited cell growth and induced apoptosis in a time- and dose-dependent manner more rapidly in and at lower concentrations in parental cells than ras-transformed cells. Expression of the sulindac sulfide arrested cells in G0/G1, but cells entered apoptosis throughout the cell cycle. Proapoptotic protein Bak was relatively high in untreated parental cells and increased markedly after sulindac sulfide but was low in untreated ras-transformed cells and did not increase after sulindac sulfide. Expression of other Bcl-2 family members was unchanged after sulindac sulfide. However, sulindac sulfide reduced levels of cyclin D1 protein and cyclin E- and cyclin D1- associated kinase activity. CONCLUSIONS: c-K-ras-transformed enterocytes are relatively resistant to sulindac sulfide-induced growth inhibition and apoptosis, which may result from specific reduction of bak expression. (Gastroenterology 1997 Dec;113(6):1892-900)     

Overexpression of the major vault transporter protein lung-resistance protein predicts treatment outcome in acute myeloid leukemia

The monoclonal antibody LRP56 recognizes a 110-kD major vault protein (lung-resistance protein [LRP]) overexpressed in several P-glycoprotein- negative (Pgp-), multidrug resistant tumor cell lines. To determine the frequency of LRP overexpression, its prognostic significance, and its relation to Pgp, we analyzed bone marrow specimens from 87 consecutive patients with acute leukemia. Diagnoses included de novo acute myeloid leukemia (AML; 21 patients), leukemia arising from an antecedent hematologic disorder or prior cytotoxic therapy (secondary AML; 27 patients), AML in relapse (29 patients), and blast phase of chronic myeloid leukemia (CML-BP; 10 patients). A granular cytoplasmic staining pattern was detected by immunocytochemistry in 32 (37%) cases, including 7 (33%) de novo AML, 13 (48%) secondary AML, 11 (38%) relapsed AML, and 1 of 10 CML-BP. Among 66 evaluable patients with AML, LRP overexpression was associated with an inferior response to induction chemotherapy (P = .0017). Remissions were achieved in 35% of LRP+ patients as compared with 68% of LRP- patients. Although Pgp adversely affected response in univariate analysis (P = .0414), only LRP had independent prognostic significance when compared in a logistic regression model (P = .0046). Differences in remission duration (P = .075) and overall survival (P = .058) approached significance only for LRP. Sequential specimens from remitting patients receiving treatment with the Pgp modulator cyclosporin-A showed emergence of the LRP phenotype despite a decrease or loss of Pgp at the time of treatment failure (P =.0304). Significant associations were observed between LRP and age greater than 55 years (P = .017), Pgp (P = .040), and prior treatment with mitoxantrone (P = .020) but not with CD34. These findings indicate that overexpression of the novel transporter protein LRP is an important predictor of treatment outcome in AML.     

Measurement of the quality of life in rheumatic disorders using the EuroQol

The EuroQol is a validated quality of life (QOL) scale that has been used in population and clinical studies, and has been reported in patients with rheumatoid arthritis (RA). It is short, simple to complete, and might be suitable for surveys of rheumatic disease patients. The properties of this instrument were investigated in a postal survey of 1372 rheumatic disease patients, including 537 with RA, 319 with osteoarthritis (OA) and 516 with fibromyalgia. In addition, simultaneous measurements of functional disability, pain, psychological status, global severity and demographic characteristics were made. EuroQol scores (0.57) were significantly lower than VAS health state scores (0.67) and arthritis-related global severity scores (0.62). QOL was similar in RA and OA, but lower in fibromyalgia, across all instruments. The distribution of EuroQol scores had many gaps and was not continuous. EuroQol did not reflect VAS QOL scores at EuroQol levels below 0.5, and the mean score difference between the instruments below that level was 0.43. Many patients with low EuroQol scores (including some with health states that were 'worse than death') had high VAS scores. These differences appear to have arisen because disability, pain and depression questions ask about mild or moderate problems, but not both, thereby forcing scale compression in the mid ranges. In addition, the 'severe' value is so extremely abnormal that few patients endorse it. Finally, penalty scores are applied to those with at least one maximally abnormal score. The scoring properties and distributional aspects of the EuroQol indicate substantial problems in its use in rheumatic disease patients.