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T A Rado

Publications and source records attributed to T A Rado.

30 records · Page 2Linked to original sources
PubMed1987

Isolation of lactoferrin cDNA from a human myeloid library and expression of mRNA during normal and leukemic myelopoiesis.

Lactoferrin is a major constituent of polymorphonuclear leukocyte granules and is present in mature neutrophils but not in blasts or promyelocytes. We have isolated a cDNA probe for lactoferrin and used it to study the synthesis of lactoferrin mRNA by normal and leukemic granulocyte precursors. The probe pHL-41 has been subcloned in phage m13 and characterized by restriction endonuclease analysis and nucleic acid sequencing. pHL-41 contains approximately 40% of the coding sequence of the lactoferrin gene. The 3' untranslated region includes a stop codon and a possible polyadenylation signal. There is a greater than 98% agreement between the cDNA-deduced amino acid sequence and that determined by analysis of the protein. Myeloid cells from normal bone marrow and circulating leukocytes from patients with chronic granulocytic leukemia contain lactoferrin mRNA transcripts that are indistinguishable in size and relative quantity. The human promyelocytic leukemia cell line HL-60 contains no lactoferrin mRNA. Induction of monocytic or granulocytic differentiation fails to induce the synthesis of detectable lactoferrin message. Similarly, studies with the human myeloblastic leukemia cell line PLB-985 reveal the inability of these cells to produce lactoferrin mRNA even under conditions that bring about morphologically demonstrable granulocytic differentiation. These data suggest that granulocytic differentiation in the leukemic cell lines is incomplete or defective. The presence of lactoferrin may play a role in the orderly expression of the genetic program leading to the development of the normal mature granulocyte.

Base Sequence↗
PubMed1987

Production of granulocyte colony-stimulating factor by a human melanoma cell line.

We have isolated a human melanoma line (LD-1) from a patient with melanoma and unexplained leukocytosis. The LD-1 cells produced a colony-stimulating factor (CSF) which stimulated primarily granulocytic colonies in human and murine bone marrow cultures. Erythroid burst and mixed colony-stimulating activity was not detected. A single CSF species with a molecular weight of 21,000 was detected in LD-1-conditioned media by G-200 chromatography. Nude mice transplanted with LD-1 tumors developed granulocytosis and had increased blood CSF levels. Messenger RNA from LD-1 cells directed the synthesis of CSF by Xenopus oocytes. Northern blots of LD-1 RNA hybridized strongly with oligonucleotide probes based on the published sequences for human G-CSF, but not with a probe based on the human GM-CSF sequence. Northern blots hybridized with an oligonucleotide probe based on the CSF-1 sequence showed a high-molecular weight band; however, low-molecular weight CSF-1 mRNAs, which are present in the CSF-1-producing cell line MIA-PaCa-2, were not detected in the LD-1 mRNA. The CSF activity of LD-1 cells is best described as human granulocyte CSF.

Adult↗
PubMed1984

Lactoferrin biosynthesis during granulocytopoiesis.

We examined the synthesis of lactoferrin, an iron binding protein that, among hematopoietic cells, is restricted to secondary granules of polymorphonuclear leukocytes. Lactoferrin biosynthesis was absent from leukemic myeloblasts and promyelocytes but abundant in normal bone marrow and both the bone marrow and peripheral blood of patients with chronic myelogenous leukemia (CGL) if the samples contained substantial numbers of myelocytes and metamyelocytes. Lactoferrin was present in the steady state in normal or CGL bands and polymorphonuclear leukocytes, but no lactoferrin biosynthesis was detectable in these samples. Taken together, these results suggest that lactoferrin accumulation begins with the onset of biosynthesis at the myelocyte stage and is largely complete by the beginning of the band stage of maturation. HL-60 cells, a permanent promyelocytic leukemia cell line, synthesized no lactoferrin. Translation of messenger RNA in Xenopus laevis oocytes revealed that mRNA from patients with chronic myelogenous leukemia and abundant myelocytes and metamyelocytes directed the synthesis of readily detectable amounts of lactoferrin, whereas HL-60 cells contained no translatable lactoferrin mRNA. We thus hypothesize that lactoferrin is a useful marker of gene expression restricted to the terminal stages of granulocyte maturation. Biosynthesis of this protein appears to be mediated by appearance of translatable mRNA at the myelocyte stage, coincident with development of secondary granules. Absence of lactoferrin production by HL-60 cells is due to absence of translatable lactoferrin mRNA, either because of lineage infidelity of these transformed cells or because of arrest before the developmental stage at which secondary granules appear.

Animals↗
PubMed1982

Constitutive expression of platelet glycoproteins by the human leukemia cell line K562.

The human leukemia cell line K562 was derived from a patient with chronic granulocytic leukemia. This cell line has subsequently been shown to possess phenotypic markers typical of erythroid and myeloid cells. Using a rabbit antiserum directed against purified platelet glycoproteins (PGPs), we have obtained evidence for the constitutive expression of PGPs on the surface of K562 cells. PGPs expressed have been tentatively identified as IIa and III based on their apparent migration in a 7% sodium dodecylsulfate polyacrylamide gel. K562 may become an important tool for the study of early events involved in megakaryocytic differentiation.

Animals↗
PubMed1978

Biochemical and morphological characterization of mycobacteriophage R1.

Large-scale propagation of mycobacteriophage R1 in broth culture has allowed the isolation of quantities of virus sufficient for characterization of its nucleic acid and lipid components as well as investigation of its ultrastructural attributes. Analysis of R1 DNA indicates that it is double stranded and possesses a molecular weight of 2.5 X 10(7) and a guanine-plus-cytosine content of 65.7 +/- 0.5%. The lipid fraction of R1 accounts for 14% of the total dry weight of the virus, 20% of which was identified as free or esterified sterols. A rapid loss of viral titer occurred after seconds of exposure to organic solvents. This result suggests that the lipid fractions of R1 is essential for its infectivity. Electron microscopic investigation of solvent-extracted R1 showed extensive deterioration of its normal morphology, including nucleocapsid disintegration and base plate separation. Routine phosphotungstate preparations demonstrated a particle with an oval head and a noncontractile tail. Altering the pH of the phosphotungstate negative stain from neutrality damage the viral particles. Uranyl formate-contrasted specimens displayed an elongated hexagonal nucleocapsid with a neck region; the cross-striated tail possessed a starlike base plate.

Cytosine↗
PubMed1976

Evidence for host-dependent modification and restriction of bacteriophage DNA in Mycobacterium tuberculosis.

Wild isolates of Mycobacterium tuberculosis may be divided into the three internationally recognized phage types on the basis of susceptibility to mycobacteriophages DS6A, BK1 and D34. Strains of type A are lysed at high efficiency by DS6A only; type B is lysed by BK1 grown on Mycobacterium smegmatis ATCC607 and DS6A, while type C is lysed additionally by D34 grown on atypical Mycobacterium F130. Propagation of D34 on a C-strain (D34-C) or BK1 on a B-strain (BK1-B) has no effect on viral host-range. D34-C has an efficiency of plating (e.o.p.) of 10(-5) on type B strains and 10(-7) on A strains. BK1-B plates on A strains at an e.o.p. of 10(-5). BK1 recovered from and repropagated on an A strain (BK1-A) has an e.o.p. of 1-0 on strains of all classes. D34-B has an e.o.p. of 1-0 on strains of type B and C, while D34-A plates with high efficiency on types B and C and displayed an e.o.p. of 10(-4) on type A. Repropagation of these viruses on the M. tuberculosis strains originally lysed by them results in the restoration of their previous host range. Variations in plating efficiency cannot be explained by differences in viral absorption alone. These findings suggest that the three phage types of human tubercle bacilli are related by a hierarchical pattern of DNA restriction and modification in which the C pattern is included in the B, and both patterns are included in A-modified DNA. Viruses such as DS6A which are equally virulent for strains of all classes are not susceptible to host dependent restriction.

Bacteriophage Typing↗
PubMed1976

Phage type of tubercle bacilli isolated from patients with two or more sites of organ involvement.

To evaluate the possibility of separate pulmonary infections in human beings by different strains of Mycobacterium tuberculosis, a search for multiple phage types within a single host was under-taken. Culture isolates from 2 or more distinct anatomic sites of infection in the same patient were obtained from 87 persons. In 3 subjects, 2 distinct phage types were found. The possible explanations for 2 types in the same patient and the epidemiologic implications are discussed.

Adult↗
PubMed1975

World Health Organization studies on bacteriophage typing of mycobacteria. Subdivision of the species Mycobacterium tuberculosis.

The ability of lytic mycobacteriophages to subdivide the species Mycobacterium tuberculosis reliably has been studied using a series of 100 strains isolated from cases of tuberculosis in the Netherlands. Techniques for the propagation and application of the viruses have been standardized, as have the conditions for growth and preparation of bacterial strains. On the basis of lytic results with 11 mycobacteriophages, it is proposed that the species Mycobacterium tuverculosis may be subdivided into at least 3 major phage types, A, B, and C, and into 2 subjects, Ax and A2. The reliability of the individual bacteriophage lytic result has been assessed, and the relationship between phage reliability and the degree of certainty with which a strain may be assigned to a phage type is described. The effect of rigorous standardization of techniques on the reliability of bacteriphage typing is demonstrated, and a standard protocol is proposed.

Bacteriophage Typing↗
PubMed1975

Evidence for infection by two distinct strains of Mycobacterium tuberculosis in pulmonary tuberculosis: report of 9 cases.

The sputum cultures of 26 patients in whom bacteriologic relapse occurred during or after an initial course of treatment with antimicrobial drugs were compared by phage typing with cultures isolated previously from the same patients. Nine (34 per cent) were different in phage type. Whether this indicates exogenous reinfection as the mechanism for the relapse, the presence of two distinct phage types present from the outset, or change in phage type of the original single strain has not been determined. These observations may have implications relating to epidemiology and control of tuberculosis.

Bacteriophage Typing↗
PubMed1971

Ribosomal competence and spore germination in Fusarium solani.

Extracts prepared from macroconidia of Fusarium solani f. sp. phaseoli are capable, under defined conditions, of incorporating phenylalanine into polypeptide with exogenous polyuridylic acid as messenger. Extracts from ungerminated and germinated spores have approximately the same activity. With endogenous template, leucine incorporation occurs, but in this reaction extracts from germinated spores have about 10 times more activity than do those from ungerminated spores. It is suggested that the low rate in ungerminated spores is attributable to a relative deficiency in the number of ribosomes which are organized into polysomes.

Carbon Isotopes↗