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Biomedical subjects

U Ringborg

Publications and source records attributed to U Ringborg.

At least 145 records · Page 8Linked to original sources
PubMed1977

Ultraviolet-induced DNA-repair synthesis in lymphocytes from patients with chronic lymphatic leukemia.

Ultraviolet-induced DNA-repair synthesis was studied in peripheral lymphocytes from 10 patients with chronic lymphatic leukemia (CLL). An ultraviolet-dose curve was established for each patient and compared with curves for healthy individuals. The same level of DNA-repair synthesis was recorded in CLL and normal lymphocytes. This contrasts with a report from another laboratory. Evidence is presented of the necessity of inhibiting replicative DNA-synthesis with hydroxyurea in order to adequately estimate the DNA-repair synthesis.

Aged↗
PubMed1976

Ultraviolet-induced dna repair synthesis in lymphocytes from patients with actinic keratosis.

Actinic keratosis is an epidermal cancer in situ. Extensive exposure to sunlight is considered as a contributing factor to the etiology of this tumor. Ultraviolet (UV) light of solar radiation induces structural damage in DNA, which may give rise to mutations and transformed cells if the damage is not repaired. Repair of UV-induced DNA lesions is an essential property of human cells. The conditions so far reported to have defective DNA repair are all associated with an increased incidence of malignancy. Do patients with actinic keratosis also exhibit a reduced capacity to repair UV-induced DNA lesions? DNA repair synthesis in peripheral leukocytes was studied in 10 patients with actinic keratosis and 10 healthy subjects of corresponding age. After irradiation with various doses of UV light the leukocytes were incubated for 2 hr with [3H]thymidine in the presence of hydroxyurea. A dose-response relationship for the UV-induced DNA repair synthesis was established for each individual. The average repair capacity in the patients with actinic keratosis was about 30% below that of the controls. The difference is statistically significant (p less than 0.02). Reduced DNA repair synthesis may therefore be an important factor in the etiology of actinic keratosis.

Aged↗
PubMed1976

Interferon therapy in Hodgkin's disease. A case report.

The treatment of a case of Hodgkin's disease (lymphocyte predominance, stage IV B) with exogenous i.m. interferon therapy is described. B symptoms disappeared, diseased nodes and pulmonary infiltrations decreased in size, and laboratory values normalized. Clinical improvement was associated with increased mitogenic responsiveness of the patient's lymphocytes towards various stimuli in vitro. After almost half a year's treatment tumour progression and a decreased mitogenic response were again observed. Interferon treatment was then abandoned and combined cytostatic courses were instituted. Partial remission was achieved after 6 months of cytostatic therapy, i.e. 1 year after the start of treatment.

Adult↗
PubMed1976

A case report including EM and DNA repair investigations in a dermatosis associated with multiple skin cancers: epidermodysplasia verruciformis.

This report describes the clinical, histological and electron microscopic observations in a 51-year-old male with epidermodysplasia veruciformis (EV). Cells with early signs of malignant transformation were found closely connected with virus infected epidermal regions. Skin cancers appeared initially on sun-exposed areas, such as the face and ear lobes. The UV-induced DNA repair synthesis was therefore studied, utilizing peripheral leukocytes. The patient had 40% lower UV-induced DNA repair synthesis than the mean of nine healthy subjects of the same age. These results suggest that a decrease in UV-induced DNA repair synthesis in combination with a possibly oncogenic viral infection may enhance the disposition for somatic mutations and malignant transformation in patients with EV.

DNA Repair↗
PubMed1972

In situ demonstration of DNA hybridizing with chromosomal and nuclear sap RNA in Chironomus tentans.

Cytological hybridization combined with microdissection of Chironomus tentans salivary gland cells was used to locate DNA complementary to newly synthesized RNA from chromosomes and nuclear sap and from a single chromosomal puff, the Balbiani ring 2 (BR 2). Salivary glands were incubated with tritiated nucleosides. The labeled RNA was extracted from microdissected nuclei and hybridized to denatured squash preparations of salivary gland cells under conditions which primarily allow repeated sequences to interact. The bound RNA, resistant to ribonuclease treatment, was detected radioautographically. It was found that BR 2 RNA hybridizes specifically with the BR 2 region of chromosome IV. Nuclear sap RNA was fractionated into high and low molecular-weight RNA; the former hybridizes with the BR 2 region of chromosome IV, the latter in a diffuse distribution over the whole chromosome set. RNA from chromosome I hybridizes diffusely with all chromosomes. Nucleolar RNA hybridizes specifically with the nucleolar organizers, contained in chromosomes II and III. It is concluded that the BR 2 region of chromosome IV contains repeated DNA sequences and that nuclear sap contains BR 2 RNA.

Animals↗
PubMed1971

Intracellular distribution of low molecular weight RNA in Chironomus tentans.

Low molecular weight RNA species are described in isolated nuclear components and cytoplasm of salivary gland cells of Chironomus tentans. In addition to 4S and 5S RNA and RNA in the 4-5S range previously described, at least three other components in the range below 16S are present. RNA, the molecular weight of which was estimated to 2.3 x 10(5) and designed 10S RNA, can be observed only in nucleoli; other RNA, the molecular weight of which was estimated to 1.3 x 10(5) and designed 8S RNA, was detected in the chromosomes, the nuclear sap, and the cytoplasm but not in the nucleoli; and a third type of RNA, the molecular weight of which was estimated to 8.5 x 10(4) and designed 7S RNA, was present in nucleoli, chromosomes, nuclear sap, and cytoplasm. The substituted benzimidazole, 5,6-dichloro-1 (beta-D-ribofuranosyl)benzimidazole (DRB), which gives a differential inhibition of the labeling of heterodisperse, mainly high molecular weight RNA in the chromosomes, does not inhibit the labeling of 8S RNA. The relative amounts of label in 8S RNA and 4-5S RNA (including 4S RNA and 5S RNA) in different isolated chromosomes, are distributed in proportion to the chromosomal DNA contents. The 8S RNA as well as the 7S RNA show a relative accumulation in chromosomes and nuclear sap with prolonged incubation time and are in this respect similar to intranuclear low molecular weight RNA species described by previous workers. Our data suggest, however, that these two types of RNA may differ in an important aspect from the previously described types since they are also present in the cytoplasm.

Adsorption↗
PubMed1971

Nucleolar-derived ribonucleic acid in chromosomes, nuclear sap, and cytoplasm of Chironomus tentans salivary gland cells.

The distribution of monodisperse high molecular weight RNA (38, 30, 28, 23, and 18S RNA) was studied in the salivary gland cells of Chironomus tentans. RNA labeled in vitro and in vivo with tritiated cytidine and uridine was isolated from microdissected nucleoli, chromosomes, nuclear sap, and cytoplasm and analyzed by electrophoresis on agarose-acrylamide composite gels. As shown earlier, the nucleoli contain labeled 38, 30, and 23S RNA. In the chromosomes, labeled 18S RNA was found in addition to the 30 and 23S RNA previously reported. The nuclear sap contains labeled 30 and 18S RNA, and the cytoplasm labeled 28 and 18S RNA. On the basis of the present and earlier analyses, it was concluded that the chromosomal monodisperse high molecular weight RNA fractions (a) show a genuine chromosomal localization and are not due to unspecific contamination, (b) are not artefacts caused by in vitro conditions, but are present also in vivo, and (c) are very likely related to nucleolar and cytoplasmic (pre)ribosomal RNA. The 30 and 23S RNA components are likely to be precursors to 28 and 18S ribosomal RNA. The order of appearance of the monodisperse high molecular weight RNA fractions in the nucleus is in turn and order: (a) nucleolus, (b) chromosomes, and (c) nuclear sap. Since both 23 and 18S RNA are present in the chromosomes, the conversion to 18S RNA may take place there. On the other hand, 30S RNA is only found in the nucleus while 28S RNA can only be detected in the cytoplasm, suggesting that this conversion takes place in connection with the exit of the molecule from the nucleus.

Animals↗