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N Ringertz

Publications and source records attributed to N Ringertz.

At least 37 records · Page 2Linked to original sources
PubMed1990

Appearance and origin of snRNP antigens in chick erythrocyte nuclei reactivated in heterokaryons.

Fusion of terminally differentiated chick erythrocytes (CE) with transcriptionally active rat myoblasts results in heterokaryons in which the CE nuclei undergo reactivation of RNA synthesis and splicing. In order to analyze the transport and assembly of small nuclear ribonucleoprotein (snRNP) particles and larger molecular complexes engaged in RNA processing, we have examined CE nuclei in heterokaryons for the presence of four U snRNP-related nuclear antigens (Sm, 70,000 Mr, F78 and M3G-cap) and for one antigen (La), associated with RNA polymerase III transcripts. Inactive erythrocyte nuclei showed low levels of Sm and F78 antigens, but the other antigens were undetectable. Immediately after fusion, the fluorescence of the pre-existing chicken Sm antigen was detected in the CEn, and then the intensity of the signal increased rapidly during reactivation. The other antigens appeared more slowly, reaching full intensity at different time points after fusion. Blocking of chick transcription did not block the appearance of Sm, 70,000 Mr, cap and La antigens but did effectively inhibit the appearance of the F78 antigen. It has previously been demonstrated that the structure recognized by this monoclonal antibody is physically associated with functional splicing complexes. Blocking of translation in heterokaryons abolished uptake of snRNPs into the chicken nuclei. Taken together, the results indicate that rat snRNP complexes were imported into the chick nuclei after assembly in the cytoplasm. For all the studied antigens, except F78, this translocation was independent of chick RNA synthesis. The appearance of the F78 antigen was totally dependent on expression of chicken genes.

Animals↗
PubMed1990

Gene expression pattern of chicken erythrocyte nuclei in heterokaryons.

Expression of erythro-specific chick genes was studied in heterokaryons prepared by fusing chick erythrocytes (CE) with rat myoblasts. In this type of heterokaryon the inactive erythrocyte nucleus takes up nuclear proteins of myoblast origin and undergoes transcriptional reactivation. In order to study the stability of the genetic programming of the reactivated CE nucleus, chick gene expression was examined by analysis of RNA from the heterokaryons. Probes for several erythro- and chick-specific genes were used. The heterokaryons showed strong expression of the chick histone H5 and adult alpha-globin genes, while other genes, e.g. the transcription factor Eryf1 gene, normally expressed during erythroid differentiation, were not transcribed. Although the CE used were of the definitive lineage, the heterokaryons showed activation of the chick embryonic beta-globin gene, i.e. a gene normally expressed only in CE of the primitive lineage. We conclude that the reactivation of the mature CE nucleus in a rat cytoplasm resulted in a more immature erythroid gene expression pattern. The activation of the embryonic beta-globin gene indicated a switch of the lineage-specific gene expression pattern. This switch occurred in the absence of DNA replication. The strong expression of the globin and H5 genes in heterokaryons, in the absence of expression of the regulatory factor Eryf1, suggested the existence of Eryf1-independent regulatory mechanisms for erythroid gene expression in these cells.

Animals↗
PubMed1981

Incidence of different morphological types of thyroid cancer in the Nordic countries.

In order to determine the incidence of different morphological types of thyroid cancer in the Nordic countries, all cases of thyroid cancer reported to the national cancer registries of Finland, Iceland, Norway and Sweden over periods ranging from 1 to 14 years were re-examined (a total of 706 cases) by one or two pathologists from each country. The age-adjusted incidence rate for Iceland was clearly higher than those for the other Nordic countries. The rate for Finland was the lowest, and a five-fold difference was seen between Iceland and Finland. The differences in the incidence rates applied to all age groups and to both sexes. The differences also concerned all histological types and were more pronounced for papillary and medullary carcinomas. In papillary carcinoma, an almost 10-fold difference was found between Finland and Iceland. The causes of the differences are not known. There has been and probably still is some endemic goitre in Finland, Norway and Sweden, but no endemic goitre occurs in Iceland. Thus, no positive association was found between the presence of endemic goitre and the risk of follicular carcinoma. There was a marked negative association between endemic goitre and the risk of papillary carcinoma.

Adenocarcinoma↗
PubMed1978

Observer variation in histologic classification of thyroid cancer.

Histologic slides of 696 cases of thyroid cancer reported to the national cancer registries of Finland, Iceland, Norway and Sweden were reviewed by 5 Nordic pathologists in order to determine the observer variation between the pathologists, as well as the reproducibility of the WHO classification of thyroid tumours. In 58% of the cases all observers agreed upon the diagnosis and in 82% at least three of them agreed. The observer disagreement was lowest for papillary carcinoma (7%) and highest for follicular carcinoma (27%). The corresponding figures for anaplastic and medullary carcinomas were 18% and 23%, respectively. The most common diverging diagnosis for cases finally interpreted as papillary carcinoma was follicular carcinoma, and for cases finally interpreted as follicular carcinoma, a benign thyroid lesion. The results of the present study clearly indicate the necessity of having all cases reviewed by the same pathologist or group of pathologists in order to obtain reliable results for comparative studies.

Adenocarcinoma↗