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Biomedical subjects

A Bank

Publications and source records attributed to A Bank.

197 records · Page 11Linked to original sources
PubMed1968

Hemoglobin synthesis in beta-thalassemia: the properties of the free alpha-chains.

The decrease in hemoglobin A (HbA, alpha(2)beta(2)) synthesis in the erythroid cells of patients with beta-thalassemia is due to a selective defect in beta-chain synthesis. Since alpha-chains continue to be formed at a normal rate in these cells, this results in a marked relative excess of alpha-chain synthesis over beta- and gamma-chain synthesis. The alpha-chains uncombined with beta- or beta-like-chains (delta, gamma) will be referred to as free alpha-chains. The experiments presented in this paper show that these free alpha-chains are capable of combining with beta-chains to form HbA and are, therefore, structurally normal. Alternatively, in the absence of added beta-chains, alpha-chains aggregates of various sizes are formed. Peripheral blood from patients with beta-thalassemia was incubated with radioactive amino acids and hemolysates were prepared. Column chromatography demonstrates that a majority of the free alpha-chains are not present in HbA. They are strongly bound to carboxymethylcellulose resin at pHs from 7.0 to 10.0, and do not elute with HbA. However, when chemically prepared hemoglobin H (Hbbeta(4)) is added to the fresh hemolysates, the free alpha-chains are readily recovered in the HbA peak. This indicates that the free alpha-chains are able to combine normally with beta-chains to form HbA. Freshly labeled hemolysates were also subjected to Sephadex G-100 chromatography. The free alpha-chains eluted as a broad peak migrating between myoglobin and hemoglobin, consistent with their forming alpha-chain aggregates of various mol wt between 16,000 and 64,000. It is suggested that the chromatographic behavior of the free alpha-chains reported herein simply reflects the chemical properties of normal alpha-chains in the absence of adequate numbers of beta- or gamma-chains. The tendency of these free alpha-chains to aggregate may lead to their intracellular precipitation and the subsequent destruction of the cells containing them.

Amino Acids↗
PubMed1967

Globin composition and synthesis of hemoglobins in developing fetal mice erythroid cells.

Fetal mouse erythropoiesis proceeds initially in yolk-sac blood islands (8 to 12 days) and, subsequently, in liver (12 to at least 16 days). Yolksac cells synthesize three hemoglobins, Hb E(I), Hb E(II) and Hb E(III). Hb E(I) has x- and y-globin chains; Hb E(II) has alpha and y; HB E(III), alpha and z. No detectable beta-globin is formed in these cells. Liver erythroid cells form only adult hemoglobin, composed of alpha- and beta-chains.

Animals↗
PubMedDate not supplied

Decreased health care use among patients with silent myocardial ischemia: support for a generalized rather than cardiac-specific silence.

OBJECTIVE: The absence of angina among patients with silent myocardial ischemia (SMI) may be a cardiac phenomenon or may reflect a generalized lack of bodily awareness and symptom reporting. We tested the hypothesis that the silence is generalized, and, therefore, that patients with SMI would make fewer health care visits for noncardiac/chest-pain problems than patients with symptomatic ischemia. METHODS: We counted all out-patient visits to our medical system for the prior 18 months for 95 patients who demonstrated ischemia during treadmill exercise testing and subsequent nuclear scanning: 62 of the patients had SMI during exercise, and 33 of the patients had symptomatic ischemia. RESULTS: Patients with SMI made were significantly less likely to have sought emergency care or primary care and had significantly fewer primary care visits than patients with symptomatic ischemia. Group differences remained after controlling for demographics and health status variables. The two groups did not differ on utilization of specialty care. CONCLUSION: The reduced use of emergency and primary care among patients with SMI suggests that they have a generalized rather than cardiac-specific reduction in somatic awareness and/or symptom reporting.

Aged↗
PubMedDate not supplied

Erythroid differentiation and the cell cycle: some implications from murine foetal and erythroleukemic cells.

On the basis of observations with (1) erythropoietin induced erythroid differentiation of foetal mouse liver proerythroblasts and (2) chemically induced expression of the erythroid program in MELC, it appears that DNA replication plays a critical role in the transition to haemoglobin formation. Erythropoietin acts selectively on proerythroblasts to stimulate first housekeeping RNA species (rRNA, tRNA), then cell proliferation and differentiation. In erythro-leukemia cells expression of the erythroid program is induced by a variety of polar compounds. DNA synthesis appears requisite to this transition to haemoglobin formation, The molecular site of action of inducing compounds is not established but it is suggested that one critical effect is on the structure of chromatin which occurs during DNA replication and results in the transcription of the erythropoietic gene program.

Animals↗
PubMedDate not supplied

Primary cardiac lymphoma treated with orthotopic heart transplantation: a case report.

Primary lymphoma of the heart is an extremely rare tumor. It is associated with a high mortality rate because of the advanced stage of myocardial involvement at initial presentation. Conventional surgical and medical treatments have not met with much success. This article reports the first case of primary cardiac lymphoma treated with orthotopic heart transplantation. The patient had hemodynamically significant severe acute rejection, neutropenic sepsis, and tumor recurrence during the late postoperative period, illustrating the difficulties associated with concomitant immunosuppression and tumor chemotherapy. Unfortunately, the patient died after a period of remission. Our approach to the integration of immunosuppression with chemotherapy, posttransplantation follow-up, and complications is discussed.

Antineoplastic Combined Chemotherapy Protocols↗