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Biomedical subjects

E Lund

Publications and source records attributed to E Lund.

At least 307 records · Page 17Linked to original sources
PubMed1984

Computed tomography of the brain following prophylactic treatment with irradiation therapy and intraspinal methotrexate in children with acute lymphoblastic leukemia.

In 28 children with acute lymphoblastic leukemia (ALL) computed tomography (CT) was performed in order to demonstrate possible cerebral changes following treatment with prophylactic irradiation and intraspinal methotrexate (MTX). The time of CT-scan examination varied from 1 year and 1 month to 10 years and 1 month after diagnosis of ALL. The age of the children ranged from 3 years and 11 months to 14 years and 5 months. Six children had normal CT scans, 12 children had slight atrophy-like changes, and nine had severe cerebral atrophy. Two patients in the latter group presented an enlarged ventricular system as well. In one patient intracerebral calcification was the only pathologic finding. The severe changes were seen in children of all age groups, but predominantly in children with a short duration of their disease, severe symptoms, and frequent marrow relapse. Changes induced by steroid therapy may be reversible. No satisfactory explanation of the demonstrated cerebral pathologic findings can be given, except that they are the consequences of the combination of total therapy and severity of disease in the individual patient. Measurement of attenuation coefficients in grey and white matter shows increasing values with age during childhood. A combination of decreasing attenuation coefficients, especially in the white matter, and the finding of severe atrophy seems to be a bad prognostic sign.

Adolescent↗
PubMed1984

Differential expression of multiple U1 small nuclear RNAs in oocytes and embryos of Xenopus laevis.

The small nuclear RNA, U1, is a highly conserved, 165 nucleotide long RNA which has been implicated in the processing of mRNA precursors. We present evidence that in the amphibian X. laevis there exist at least seven species of U1 RNA, which differ in sequence but not in length. Strikingly, these RNAs are not coordinately expressed. Two of the U1 RNAs are the predominant U1 species transcribed in the late blastula-early gastrula stages of Xenopus embryogenesis. These two RNAs, designated xU1a and xU1b, are not synthesized in significant amounts in stage 6 oocytes; a different set of U1 RNAs are expressed during late oogenesis. In a Xenopus cultured cell line, all of the U1 RNA species are expressed. Possible functions and developmental significance of these multiple U1 RNA species are discussed.

Animals↗
PubMed1984

Nucleotide sequences of two regions of the human genome containing tRNAAsn genes.

The primary structures of two human tRNAAsn genes and 600-700 nucleotides of their flanking regions have been determined from two separate isolates of a fetal DNA library in phage lambda vector. The tRNA gene from one clone differs from the major mammalian tRNAAsn by a single base substitution at position 47, with an A replacing a G, while the tRNAAsn gene from the second clone has base substitutions at positions 17 and 65, with a G replacing a C and a T replacing a C, respectively. The sequences of the noncoding 5'- and 3'-flanking regions of both clones are over 90% homologous. As with other mammalian tRNA genes, these two human tRNAAsn genes contain CTTTTPu, which might act as a transcription termination signal, 11 bp 3' to the structural gene. In vitro transcription experiments in a HeLa cell extract demonstrate that both cloned tRNAAsn genes can be transcribed and processed to mature-sized tRNAs.

Aspartate-tRNA Ligase↗
PubMed1984

Human U1 RNA genes contain an unusually sensitive nuclease S1 cleavage site within the conserved 3' flanking region.

We find that the cloned DNAs of human U1 small nuclear RNA genes contain two nuclease S1-sensitive sites, one about 1.8 kilobases downstream of the U1 RNA coding region and the other around 0.3 kilobase upstream. The downstream site is unusually sensitive to the nuclease, being cleaved in both linear and negatively supercoiled DNAs. The extent of cleavage at this site is enhanced at lower pH and reduced concentrations of NaCl; the effects of salt are more apparent on linear than supercoiled DNAs. The nuclease S1 sensitivity of this downstream site is dependent on the presence of the sequence (dC-dT)n X (dA-dG)n, where n = 15-25. (One gene with n = 5 is resistant to nuclease S1 cleavage in this region.) In contrast, the nuclease S1 site upstream of the coding region is cleaved only when the DNA is supercoiled. This site also has a homopyrimidine X homopurine bias in the DNA strands, but the sequence is less regular. In the course of these studies, we detected several discrepancies between our restriction maps of some U1 RNA genes and those published by others. Our maps demonstrate that all seven cloned human U1 RNA genes are very similar in sequence for as much as 2.3 kilobases downstream of the U1 RNA coding region.

Base Sequence↗
PubMed1984

Acute interstitial pneumonitis caused by Aleutian disease virus in mink kits.

In four Danish mink ranches acute interstitial pneumonitis caused excessive mortality among kits within the first 2 1/2 months after parturition. The disease was found to be due to an Aleutian disease virus (ADV) and could be reproduced experimentally in neonatal kits by inoculation with material from spontaneous cases, as well as with other strains of ADV. Experimental reproduction was only possible in kits from dams free of Aleutian disease (AD) whereas kits from dams experimentally or naturally infected with ADV developed no lung changes. Presently available evidence indicates that the initial lung lesions result from primary viral injury to type II alveolar cells, and that immune mechanisms, essential for the development of traditional AD, are not involved in the pathogenesis.

Aleutian Mink Disease↗
PubMed1984

The two embryonic U1 small nuclear RNAs of Xenopus laevis are encoded by a major family of tandemly repeated genes.

We have identified a large family of U1 RNA genes in Xenopus laevis that encodes two distinct species of U1 RNA. These genes are expressed primarily at the onset of transcription in the 4,000-cell embryo (D. J. Forbes, M. W. Kirschner, D. Caput, J. E. Dahlberg, and E. Lund, Cell 38:681-689, 1984). The two types of embryonic U1 RNA genes are interspersed and are organized in large tandem arrays. The basic 1.9-kilobase repeating unit contains a single copy of each of the embryonic genes and is reiterated ca. 500-fold per haploid genome. This repetitive U1 DNA accounts for more than 90% of all U1 DNA in X. laevis. In addition to this major family, there exist several minor families of dispersed U1 RNA genes, which presumably encode the oocyte and somatic species of X. laevis U1 RNA. Although the embryonic genes are normally inactive in stage VI oocytes, they are expressed when cloned copies are injected into oocyte nuclei.

Animals↗
PubMed1983

Ribosomal RNA precursors of Bacillus subtilis.

The DNA sequence of the region corresponding to the 5'-end of a 16S rRNA gene of B. subtilis 168 was determined. Comparison of this sequence with the sequences flanking other 16S and 23S rRNA coding regions (1-4) indicated that large RNA stem structures, surrounding the mature 16S and 23S rRNAs, could form in a precursor rRNA. The 5'-ends of the precursors of 16S and 23S rRNAs (p16S and p23S) were mapped to the middles of these potential RNA stem structures. We propose that the initial cleavages of the primary rRNA transcript occur near the "opposed G's" which interrupt the basepairing of each of these stem structures. This model is supported by the finding that the 5'-end of the 5S rRNA precursor, p5A (5), maps to the region of the "opposed G's" in the 23S rRNA stem structure.

Bacillus subtilis↗
PubMed1983

Isolation and characterization of genomic mouse DNA clones containing sequences homologous to tRNAs and 5S rRNA.

We have cloned and characterized three fragments of Balb/c mouse DNA which hybridize to mouse cell tRNAs. Fractionation of the tRNAs which hybridize to these clones reveals that two of the clones, lambda Mt-4A and lambda Mt-6A hybridize to only one or two tRNAs, while one clone, lambda Mt-4B, hybridizes to at least seven tRNAs. Two of the tRNAs were identified as tRNAProCCG and tRNAGlyGGA, and others have been identified as tRNAs which are selectively encapsidated into virions of murine leukemia virus and avian reticuloendotheliosis virus. The DNA sequences of putative genes for tRNAProCCG and tRNAGlyGGA, plus flanking regions, were determined. A clone of Balb/c mouse DNA which selectively hybridized to 5S rRNA was also isolated and partially characterized.

Animals↗