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M Ekblom

Publications and source records attributed to M Ekblom.

35 records · Page 2Linked to original sources
PubMed1990

Transient and locally restricted expression of laminin A chain mRNA by developing epithelial cells during kidney organogenesis.

Three polypeptide chains, A, B1, and B2, have been described for mouse laminin, a basement membrane protein. We studied expression of laminin A, B1, and B2 mRNA in the developing mouse kidney. Induction of kidney mesenchyme differentiation in vitro led to an increased expression of B1 and B2 chain mRNA on day 1 of development. In contrast, expression of A chain mRNA increased on day 2, when epithelial cell polarization begins. Laminin A mRNA and polypeptide were expressed only by epithelia during in vivo development as well. Some polarized cell types producing basement membrane (endothelium, some adult epithelia) lacked the A chain mRNA and polypeptide, although they did express B chains. Laminin with the 400 kd A chain is therefore a transient form appearing at specific sites of kidney morphogenesis, whereas isoforms with a different A chain or without it have a more widespread distribution.

Animals↗
PubMed1990

A genomic clone encoding a novel proliferation-dependent histone H2A.1 mRNA enriched in the poly(A)+ fraction.

Replication-dependent histone mRNAs are prime examples of nonpolyadenylated mRNAs. We isolated and characterized cDNAs and a genomic clone for a replication-dependent histone H2A.1 mRNA which segregated into the poly(A)+ fraction during mRNA isolation through an oligo(dT)-cellulose column. However, the results of sequencing of the genomic clone suggested that the mRNA did not contain a poly(A) tail. Instead, the genomic sequence revealed a nonterminal oligo(A) tract directly upstream from the typical 3'-terminal hairpin loop of replication-dependent histone mRNAs. The nonterminal oligo(A) tract consisted of 14 adenylate residues interrupted by one guanylate residue (A4GA10). We concluded that this short oligo(A) stretch mediated binding of the mRNA to oligo(dT) even after stringent washes with 0.1 M NaCl, indicating that rather short oligo(A) sequences can ensure binding to oligo(dT)-cellulose. The cDNA and genomic clones contained an AAATAAG sequence at the end of the coding region. It has been suggested that this sequence contains a polyadenylation signal in some yeast and mouse transcripts, but it does not function as a polyadenylation signal in the histone transcript described in this paper.

Amino Acid Sequence↗
PubMed1990

Differential expression of laminin A and B chains during development of embryonic mouse organs.

Laminin is a large glycoprotein of basement membranes. The best described laminin from a mouse tumor contains three polypeptide chains (A, B1 and B2), but there is recent evidence that some cell types produce laminin isoforms lacking the A chain. We have here studied the occurrence of the isoforms during mouse organogenesis. In all tissues studied, the A chain mRNA and polypeptide were more weakly expressed than those of the B chains. Laminin A chain polypeptides showed a much more restricted tissue distribution than the B chains. Laminin A chain polypeptide was mainly detected in basement membranes of epithelial cells, suggesting that this chain is important for morphogenesis of epithelial sheets. Most endothelial basement membranes and all embryonic mesenchyme matrices studied seemed to lack the A chain even though they contained B chains. Several of the cells producing laminin devoid of A chain seem to produce other polypeptides that become complexed to the B chains. With an anti-laminin antiserum, which in immunoblots reacts only with A and B polypeptide chains, additional polypeptides of 160 and 190 x 10(3) Mr were co-precipitated from all tissues studied. In developing heart, a polypeptide of 300 x 10(3) Mr was co-precipitated in addition. Our data suggest that these laminin-associated polypeptides are not formed by a differential splicing of the known A chain mRNA. Northern blotting of poly (A)+ RNA showed only 10kb A chain transcripts but no truncated forms. We conclude that several cell types in the mouse embryo produce laminin variants that lack the 400 x 10(3) Mr A chain. Since a major cell binding site of laminin contains parts of the A chain, the variants should differ in biological function from laminin containing this A chain.

Animals↗
PubMed1989

Effect of bumetanide on tubuloglomerular feedback in Necturus maculosus.

A non-invasive technique was developed to measure single-nephron glomerular blood flow (SNGBF) in Necturus maculosus. Erythrocytes labelled with rhodamine, a fluorescent dye, were injected systemically and the frequency at which labelled cells entered an arteriole was measured. Frequency was converted to flow by measuring the concentration of labelled erythrocytes in whole blood. Dependence of SNGBF on flow rate in early distal tubules was used to assess tubuloglomerular feedback (TGF). SNGBF decreased with increasing flow in the early distal tubule in a pattern typical of TGF; SNGBF decreased 25% at the highest flow rates. SNGBF increased when bumetanide was added to the perfusate, but the TGF response to flow rate persisted. IC50 (concentration that produces half-maximal inhibition) was 2.4 x 10(-10), 9.8 x 10(-10) and 1.2 x 10(-9) M bumetanide at distal perfusion rates of 5, 10 and 20 nl min-1 respectively. These results are consistent with modulation of SNGBF according to the rate of luminal entry of NaCl into early distal tubule cells. This transport rate depends on the luminal concentration of NaCl, which is tubular flow rate-dependent; NaCl and bumetanide compete.

Animals↗
PubMed1987

Familial and sporadic medullary thyroid carcinoma: clinical and immunohistological findings.

We have studied the clinical and thyroid immunohistological features of 19 patients with sporadic medullary thyroid carcinoma and 16 patients with the hereditary syndrome multiple endocrine neoplasia 2a (MEN 2a). Both groups were identified by family screening using serum calcitonin determinations before and after pentagastrin stimulation. Pheochromocytoma and hyperparathyroidism were associated both with multiple endocrine neoplasia 2a and some cases of sporadic medullary thyroid carcinoma. Hereditary medullary thyroid carcinoma was invariably associated with C-cell hyperplasia, but C-cell hyperplasia was also associated with some sporadic tumours. All tumours were positive for calcitonin and carcinoembryonic antigen (by immunohistological staining) (CEA) and most tumours stained for somatostatin. C-cell hyperplasia also stained for calcitonin, CEA and somatostatin. We conclude that sporadic and familial medullary thyroid carcinoma cannot always be discriminated by clinical or immunohistological methods. Family screening is essential in the diagnosis of hereditary medullary thyroid carcinoma.

Adult↗
PubMed1985

Late expression of M and N antigens on glycophorin A during erythroid differentiation.

The M/N blood groups are carried by the major human red cell sialoglycoprotein, glycophorin A. O-glyosidic carbohydrate is needed for the activity, but the M/N specificity is due to amino acid replacements in the NH2-terminal portion of the molecule. We have used monoclonal antibodies specific for M and N blood groups to study their expression during normal erythropoiesis. Here we report that the M/N blood group activities are very weakly or not at all expressed before the polychromatic normoblast stage. Using polyclonal anti-glycophorin A antiserum, it was shown that glycophorin A molecules are already abundantly present on the earliest morphologically recognizable erythroid precursor, the proerythroblast. These findings can be explained by our previous observation that the O-glycosylation of glycophorin A gradually increases during erythroid maturation.

Antibodies, Monoclonal↗
PubMed1984

Critical chromosome rearrangement in acute promyelocytic leukemia.

We report here a patient with acute promyelocytic leukemia (APL) who has two normal chromosomes #15 but a structurally abnormal chromosome #17. This case indicates that the critical point of rearrangement in APL is not necessarily in chromosome #15 but may, alternatively, be in chromosome #17.

Bone Marrow↗
PubMed1984

Chromosome abnormalities in 16 Finnish patients with Burkitt's lymphoma or L3 acute lymphocytic leukemia.

Eleven patients with Burkitt's lymphoma (BL), i.e., small noncleaved non-Hodgkin's lymphoma, and 5 patients with Burkitt-type acute lymphocytic leukemia (ALL-L3) were selected for chromosome study. Two of the 16 patients had no B-cell markers, but the erythrocyte marker--glycophorin A--was present on the surface of the leukemic blasts. The critical breakpoint at 8q24 was detected in 14 of the 16 patients, whereas this aberration was not detected in any of the 134 patients belonging to other subgroups of non-Hodgkin's lymphoma or ALL that we studied during the same period. In addition to the t(8;14)(q24;q32), the following translocations with the breakpoint at 8q24 were seen: t(2;8)(p11;q24), t(8;11)(q24;q13) in BL, and t(2;8;14)(p11 or p12;q24;q32) in ALL. Additional aberrations seen more than once were trisomy #7 and abnormalities in chromosomes #1, #11, and #13.

Adolescent↗
PubMed1984

Differentiation of human erythroid cells is associated with increased O-glycosylation of the major sialoglycoprotein, glycophorin A.

Glycophorin A, the major human erythrocyte sialoglycoprotein, is found exclusively on cells of the erythroid lineage. The amino acid sequence is known, and glycophorin A isolated from mature erythrocytes contains a single N-glycosidic and 15 O-glycosidic oligosaccharides. Monoclonal antibodies against erythrocyte glycophorin A reacted weakly with erythroid precursors while a monospecific rabbit antiserum reacted strongly with immature and mature red cells. Glycophorin A was isolated from cells representing various stages of erythropoiesis in normal bone marrow, from blood cells of neonates with erythroblastosis fetalis, and from the erythroleukemic cell lines K562 and HEL before and after induced differentiation. Analysis of the oligosaccharides showed less O-glycosylation of glycophorin A in erythroid precursors. The degree of glycosylation increased concomitantly with differentiation.

Bone Marrow Cells↗
PubMed1984

Expression of spectrin in normal and malignant erythropoiesis.

Spectrin is a major constituent of the erythrocyte membranoskeleton. The occurrence of spectrin during normal and malignant erythropoiesis was investigated by immunofluorescence using a monospecific rabbit anti-human spectrin antiserum. The expression of spectrin was correlated to the presence of glycophorin A, which is an early and specific marker for erythroid cells. The expression of spectrin during normal erythroid differentiation coincided with that of glycophorin A. Both markers were already present in the proerythroblasts. Spectrin was also found in leukaemic cells from patients with acute erythroleukaemia and erythroid blast crisis of chronic myelogenous leukaemia. In a large panel of human haematopoietic cell lines only those with erythroid phenotype (K 562 and HEL) stained positively for spectrin. It is concluded that spectrin appears early in the erythroid maturation. It is expressed both in normal and malignant erythroid precursors. Spectrin can be used as a marker for erythroid blasts in the diagnosis of erythroleukaemias.

Animals↗
PubMed1984

Immunological monitoring of bone marrow transplant recipients. I. Major leucocyte subclasses in the blood.

In the recipients of an allogeneic HLA-identical sibling transplant the blood leucocytes were reconstituted within 3 to 4 weeks but the level of lymphocytes remained low throughout the observation period of 20 weeks. Of the different lymphoid cell subsets, the large granular lymphocytes (LGL) reconstituted fastest, followed by DR-expressing lymphocytes. The reconstitution was accompanied by a significant lymphoid blastogenesis in the blood. The frequency of OKT4 and OKT8 lymphocytes was initially low; the number of OKT8-positive lymphocytes reached normal levels by the 6-8th week whereas the number of OKT4-positive lymphocytes and, consequently, the OKT4/8 ratio remained low. The responses to the T mitogens, phytohaemmagglutinin and concanavalin A, were strongly suppressed. Only a few significant changes were observed before and during acute graft-versus-host disease (aGVHD): the frequency of LGL, lymphoid blasts and OKT8-expressing lymphocytes was depressed before aGVHD and the frequency of lymphoid blasts remained depressed throughout the episode. We conclude that reproducible changes occur in the leucocyte subset frequencies during reconstitution, but the characteristic changes prior to and during aGVHD are not particularly prominent and hardly of diagnostic use.

Adult↗
PubMed1984

A method for simultaneous study of the karyotype, morphology, and immunologic phenotype of mitotic cells in hematologic malignancies.

A major problem in the cytogenetic analysis of hematologic neoplasms has been an inability to identify the cell from which the chromosomes were obtained. We describe a procedure that allows simultaneous analysis of karyotype and cell cytology in mitotic cells. The method differs from conventional cytogenetic analysis in that after mild hypotonic treatment, the cells are cytocentrifuged onto glass slides. In mitotic cells, this procedure often results in adequate spread of the chromosomes within the intact cell membrane. The cytoplasmic structure also remains intact, so that cytologic preparations are of good quality. Morphologic and immunologic identification of mitotic cells can be done using routine hematologic stains, such as Giemsa or Sudan black B, and various antisera using immunofluorescence techniques. The chromosomes can be simultaneously analyzed either without banding on slides stained with Giemsa or with Q-banding on slides stained with immunofluorescence techniques. Identification of numerical and structural karyotype aberrations thus is possible in morphologically identified cells.

Aged↗
PubMed1983

Erythroid blast crisis in chronic myelogenous leukemia.

Blood or bone marrow specimens from 22 patients with chronic myelogenous leukemia in blast crisis were studied for the surface expression of glycophorin-A, a marker for early erythroid differentiation. The leukemic blasts were stained with rabbit anti-glycophorin-A antiserum. The glycophorin-A molecules detected by the rabbit antiserum were identified by polyacrylamide slab gel electrophoresis of the immunoprecipitates from the membrane lysates of surface-labeled blasts. Blasts expressing surface glycophorin-A were found in 9 of the 22 patients. In 4 patients, almost all blasts were glycophorin-A positive, and in 5 patients, less than half of the blast population expressed glycophorin-A. The present study shows that when glycophorin-A is used as a marker for erythroid blasts, involvement of the erythroid lineage during blast crisis of chronic myelogenous leukemia seems to occur more frequently than previously recognized.

Adolescent↗
PubMed1982

Acute erythroleukaemia with L3 morphology and the 14q+ chromosome.

L3 morphology according to the FAB classification and the 14q+ chromosome are usually ascribed to the Burkitt type of leukaemia or lymphoma with a B or pre-B cell phenotype. We report here a case of adult acute leukaemia with Burkitt morphology and the 14q+, which did not express lymphoid markers. Instead, the leukaemia was shown to be an acute erythroleukaemia. The erythrocyte marker glycophorin A was present on the surface of the leukemic blasts as shown by immunofluorescence and immunoprecipitation from membrane lysates of surface labeled cells with antiglycophorin A antiserum. Spectrin and fetal hemoglobin appeared after cultivation of the blasts in the presence of sodium butyrate. The present case shows that a short term cultivation is sometimes useful for further characterization of the commitment of acute leukaemias.

Acute Disease↗
PubMed1981

Pituitary function in patients with enlarged sella turcica and primary empty sella syndrome.

The pituitary function in 20 patients with primary empty sella syndrome has been evaluated. The only endocrine symptom was secondary amenorrhoea in four patients. In half of the patients, pituitary function tests showed minor abnormalities, the most common being impaired growth hormone response to glucagon. In addition to the empty sella, other intracranial abnormalities such as pituitary tumour and hydrocephalus were found in four patients. Although commonly a benign condition, the empty sella may occasionally be associated with clinically important endocrine dysfunction, pituitary tumours and other intracranial abnormalities.

Adult↗
PubMed1978

Costs and benefits of measles vaccination in Finland.

Measles vaccination is fairly beneficial. During the third year after launching of the vaccination programme, cumulative benefits accuring from vaccination outweigh the cumulative costs of vaccination. This conclusion is based on a study of the vaccination programme in Finland. According to the vaccination programme, all 1-year-old infants in Finland are vaccinated. The duration of the period under survey has been set at 25 years, the measuring unit is the Finnish mark and the price level is that of the year 1975. When comparing costs and benefits, these are converted to present day monetary values. Vaccination costs per vaccinated infant amount to 32 marks, and in total during the period 1975--1999 they will amount to about 34 million marks according to an interest rate of 9% and to about 41 million marks according to an interest rate of 6% in current monetary value. Benefits gained by vaccination, compared with costs, are manifold. The benefits of one vaccination have been estimated at 230 marks. In total, benefits during the period 1975--99 constitute ca 117 million marks at an interest rate of 9%, and ca 159 million marks at an interest rate of 6% in current monetary value, without any deduction for vaccination costs. The net gain of vaccination--with a deduction of vaccination costs--is ca 84 million marks at an interest rate of 9%, and ca 118 million marks at an interest rate of 6% in current monetary value.

Child, Preschool↗