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Biomedical subjects

O J Martelo

Publications and source records attributed to O J Martelo.

At least 37 records · Page 2Linked to original sources
PubMed1980

Emergence of immunoblastic sarcoma in Waldenstrom's macroglobulinemia.

A case involving a 65-year-old man with Waldenstrom's macroglobulinemia (WMG) which transformed into immunoblastic sarcoma is presented. Surface IgM (kappa) was demonstrated on the plasmacytoid lymphocytes of the bone marrow at presentation as well as on the less differentiated cells of the immunoblastic sarcoma. Serum IgM levels fell at the time that immunoblastic transformation occurred. This case illustrates the fact that a fall in serum paraprotein may herald a malignant transformation of WMG.

Aged↗
PubMed1979

The effect of INH-inhibited heme synthesis on globin synthesis.

In the rabbit reticulocyte cell-free system, optimal globin synthesis is dependent upon an adequate level of heme. The effect of heme is mediated by an inhibitor of globin synthesis initiation termed HCR. In addition to marked inhibition of total globin synthesis, HCR results in a decreased alpha/beta globulin synthesis ratio. We describe here the use of INH as a relatively nontoxic inhibitor of heme synthesis in intact rabbit reticulocytes with a resultant inhibition of globin synthesis. In parallel with the inhibition of globin synthesis in reticulocytes, an inhibitor of globin synthesis in the hemin-supplemented cell-free system is generated. No INH-induced alterations in alpha/beta synthesis ratio could be found in "stress" reticulocytes from phenylhydrazine-treated rabbits, but "normal" reticulocytes from untreated rabbits showed a decreased alpha/beta ratio. Inhibition of heme synthesis and the resulting decrease in globin synthesis and intracellular hemoglobin concentration may have application as a potential treatment of homozygous sickle cell disease.

Animals↗
PubMed1978

Purification and properties of a nuclear protein kinase associated with ribonucleic acid polymerase I.

A cyclic AMP-dependent nuclear protein kinase was found to be closely associated with rat liver nucleolar RNA polymerase I throughout most of its purification. This protein kinase was purified to near homogeneity. It exhibits a number of unusual catalytic properties, including the inability to utilize Mn2+ when RNA polymerase is the substrate and the ability to phosphorylate both acidic and basic substrates. Phosphorylation of RNA polymerase I by this protein kinase results in the formation of phosphoester bonds characteristic of phosphoserine and phosphothreonine. Radioautography of polyacrylamide-gel electrophoretograms of the phosphorylated RNA polymerase I revealed that the 32P was located primarily on enzyme subunits SA1, SA3, SA5, and SA6 [nomenclature of Kedinger, Gissinger & Chambon (1974) Eur. J. Biochem, 44, 421-436].

Animals↗
PubMed1978

Asynchronous globin chain synthesis in rabbit reticulocyte lystates induced by hemin-controlled repressor.

To define further the role of hemin-controlled repressor (HCR) in globin synthesis, we studied its effect on the synthesis of individual globin chains in a rabbit reticulocyte lysate cell-free system. In the presence of HCR there was a marked globin chain imbalance, resulting in a lowered alpha/beta ratio. These findings in vitro may have relevance to certain clinical heme deficiency states in which a similar globin chain imbalance has been observed.

Animals↗
PubMed1978

Primary sideroblastic anemia masked by bleeding.

A patient with characteristic features of iron deficiency was unexpectedly found to have circulating siderocytes. Bone marrow iron stain at this time showed absence of both hemosiderin and ringed sideroblasts; electron microscopy revealed absence of mitochondrial iron loading but presence of cytoplasmic ferritin in normoblasts. Replenishment of iron stores led to development of typical sideroblastic anemia. These observations suggest that increased percentage of siderocytes in otherwise typical iron deficiency anemia may signify the presence of a sideroblastic process masked by iron deficiency due to bleeding.

Aged↗
PubMed1976

Phosphorylation of rat liver ribonucleic acid polymerase I by nuclear protein kinases.

Phosphorylation of rat liver RNA polymerase I occurred when intact rat liver nuclei were incubated with [gamma32P]ATP and N6,O2' dibutyryl cyclic 3':5'-AMP. In addition, partially purified RNA polymerase I could be phosphorylated in vitro by an endogenous protein kinase. Phosphorylation by either method was followed by extensive purification of the enzyme. This revealed that 32P remained bound to the enzyme throughout purification. Analysis of the homogeneous labeled protein by polyacrylamide gel electrophoresis under nondenaturing conditions followed by autoradiography revealed that only one of the two forms of RNA polymerase I in rat liver nuclei was phosphorylated. RNA polymerase II was not phosphorylated in intact nuclei. Polyacrylamide gel electrophoresis of the phosphorylated RNA polymerase I in the presence of 0.1% sodium dodecyl sulfate followed by autoradiography demonstrated that the 32P was located primarily on enzyme subunits SA1, SA3, and SA5-SA6. High voltage paper electrophoresis of a partial acid hydrolysate of phosphorylated RNA polymerase I revealed that both serine and threonine residues were phosphroylated. N6,O2'-Dibutyryl cyclic 3':5'-AMP stimulated endogenous RNA polymerase I activity and endogenous nuclear protein phosphorylation in intact nuclei. These results suggest that phosphorylation of RNA polymerase I by nuclear protein kinases may play a role in the control of transcription in mammalian cells.

Animals↗
PubMed1976

Activation of renal erythropoietic factor by phosphorylation.

Renal erythropoietic factor (REF) serves as a substrate for a cyclic nucleotide-dependent protein kinase. The phosphorylation of REF is associated with increased erythropoietic activity. Conversely, REF isolated from hypoxic rats is a poor phosphate acceptor. These findings and the presence of a positive correlation between erythropoietin levels and urinary excretion of adenosine 3',5' monophosphate (cyclic-AMP) in anemic individuals suggest that the cyclic-AMP-protein kinase system plays an important role in the activation of REF.

Anemia↗
PubMed1975

Immunologically-mediated renal disease in Waldenström's macroglobulinemia.

A patient with Walderström macroglobulinemia associated with nephrotic syndrome is described. Serum cryoglobulin and rheumatoid factor were absent. Intramembranous electron-dense deposits were demonstrated in kidney biopsy material by electron microscopy. Deposits of immunoglobulin G (IgG), M (IgM) and the third component of complement (C3) were identified in kidney biopsy tissue by immunofluorescent staining methods. The serum immunoglobulins were characterized by chromatographic and immunochemical methods and showed a monocional IgM-K, IgG-K and gamma-chain piece of undefined structure. Free K- and gamma-chains were found in the urine. The IgM was not complexed to the IgG or vice versa, but the IgG was in an affregated form. Although it is not known which immunoglobulin initiated the tissue injury, IgG, IgM and complement deposits probably contributed to the renal dysfunction. The nephrotic syndrome diminished after treatemnt with chlorambucin and corticosteroids.

Animals↗