Small lymphocyte production and lymphoid cell proliferation in mouse bone marrow

Summary In mice given³H-thymidine systemically during temporary circulatory occlusion of one hind limb, comparison of the labeling of rapidly-renewing small lymphocytes in the tibial marrows demonstrated that these cells were locally produced. Labeling by³H-thymidine infusion revealed that many marrow large lymphoid cells, presumptive small lymphocyte progenitors, had a marked proliferative activity and rapid turnover which varied according to cell size, was maximal in young mice and declined with increasing age.This work was supported by a grant from the Medical Research Council of Canada. The technical assistance of Mrs E. D. Watson is acknowledged.     

In vitro culture of chick down feather bulbi: a tool to obtain proliferating and differentiating keratinocytes in an organotypic structure

Chick down feather bulbi can be cultured in different culture systems. Morphological analysis and 3H-thymidine incorporation measurements prove that the majority of cells are viable epithelial cells.     

Cell cycle changes after denervation of the newt limb regenerate,studied in vitro

Summary The proliferation of the mesenchyme of medium bud stage blastemas ofPleurodeles, measured by³H-thymidine incorporation and mitotic index, decreases about 40–50% under denervated conditions when cultivated in vitro for 4 days; epidermis is not affected in this case. Autoradiography of blastemas after³H-thymidine long term labeling shows that 3/4 of the mesenchymal cells and 1/4 of the epidermal cells are cycling when the blastema is innervated; there is no significant change of these percentages when the blastema is denervated. The results show, contrary to in vivo experiments, that denervation does not provoke an exiting from the cell-cycle but only lengthening of the cycle of the mesenchymal cells (probably of the G₁ phase).     

In vitro culture of chick down feather bulbi: A tool to obtain proliferating and differentiating keratinocytes in an organotypic structure

Summary Chick down feather bulbi can be cultured in different culture systems. Morphological analysis and³H-thymidine incorporation measurements prove that the majority of cells are viable epithelial cells.     

Dose-effects of 8-methoxypsoralen and long wave UV-light in 3T3 cells: evaluation of phototoxic index.

3T3 cells were cultured until confluency and treated with various doses of 8-methoxypsoralen followed by long wave UV light irradiation. The inhibition of 3H-thymidine incorporation was dose-dependent for both, psoralen and light. A phototoxic index (PTI) was established demonstrating that a constant correlation between psoralen and UVA light exists for the photoinactivation in living cells.     

Dose-effects of 8-methoxypsoralen and long wave UV-light in 3T3 cells: evaluation of a phototoxic index

Summary 3T3 cells were cultured until confluency and treated with various doses of 8-methoxypsoralen followed by long wave UV light irradiation. The inhibition of³H-thymidine incorporation was dose-dependent for both, psoralen and light. A phototoxic index (PTI) was established demonstrating that a constant correlation between psoralen and UVA light exists for the photoinactivation in living cells.Supported by Deutsche Forschungsgemeinschaft.We thank Miss Anne Schröder for her skillful assistance.     

Die DNS-synthese im rattenherzen als funktion des lebensalters. Autoradiographische untersuchungen mit3H-thymidin

Summary The percentage of DNA-synthesising heart muscle nuclei of white rats (³H-thymidine, autoradiography) decreases rapidly during the first month of life reaching a minimum at the fourth month. From then up to 27 months the number of labelled muscle nuclei remains rather constant. Also in nuclei of connective tissue the³H-thymidine labelling index decreases as a function of the rats age. The number of mitotic figures is always about 10 times lower than labelled nuclei. Mostly in heart muscle cells they occur as collapsed mitoses never leading to cytoplasma division¹⁴.     

delta-9-Tetrahydrocannabinol (THC) inhibition of the membrane transport system for thymidine]

THC decreases 3H-thymidine uptake within 15 sec. after addition of the drug to the culture (L1210 murine lymphoma cells and human lymphocytes). Experiments performed at 0 degrees C indicate that THC has no action on thymidine binding to the carrier. THC in micromolar concentration inhibits DNA synthesis through a alteration of membrane configuration.     

3H-thymidine incorporation (DNA synthesis) and radiotoxicity in the ovary of the Japanese quail before and during follicle formation

No evidence was found for ribosomal DNA amplification in the oocytes of the Japanese quail, before or during folliculogenesis. DNA synthesis in the somatic cells, involved in follicle formation, starts at the medullar side of the basement membrane. The localized sterilization of the quail ovary after administration of 3H-thymidine (3H-TdR) seems to be due to radiation-induced lesions in the follicle forming somatic cells, rather than to direct radiation damage of the oocyte.     

Regulation of macronuclear DNA content during the cell cycle of the ciliate Tetrahymena paravorax (microstome form)]

Results of autoradiographic studies of 3H-thymidine incorporation support a model of macronuclear DNA content regulation involving an action upon the extremes of DNA content: elimination of S phase in cells with large DNA content, additional S phase in cells with DNA content. The frequency of each of these phenomena is about 20%: the inequality of frequencies obtained with the two types of sister cells (proters and opisthes) is relatable to the asymetry of cytodieresis observed in this ciliate.     

Continuous labelling method for autoradiographic analysis of cell cycle parameters in steady state cell systems

Summary Under certain conditions, continuous availability of³H-thymidine in steady-state cell systems results in a linear increase of the fraction of labelled cells, the equation of which can be used to determine cell cycle parameters of the system investigated.This research was supported by the Deutsche Forschungsgemeinschaft.     

Effect of epidermal growth factor on growth and maturation of fetal and neonatal rat small intestine in organ culture

Small intestinal explants from pre- and post-natal rats were incubated in an organ culture system in the absence and presence of epidermal growth factor (EGF). The rate of synthesis of small intestinal DNA and protein as well as the activity of lactase and alkaline phosphatase increased rapidly between 17 and 20-day gestational age, whereafter they declined. The maximal incorporation of 3H-thymidine and 14C-alanine into DNA and protein, respectively, was significantly stimulated by EGF (100 ng/ml). EGF had no effect on the activity of either lactase or alkaline phosphatase in the small intestinal explants.     

Untersuchungen über den Wirkungsmechanismus von Procarbazin (Natulan®)

Summary The cytotoxic methylhydrazine derivative procarbazine or Natulan® has a marked influence on the synthesis of deoxyribonucleic acid in Ehrlich ascites carcinoma cells. The incorporation of³H-thymidine into DNA — measured by autoradiographic methods — is inhibited.     

DNA synthesis in exocrine and endocrine pancreas after partial hepatectomy in Syrian golden hamsters

3H-thymidine autoradiography showed an enhanced DNA synthesis in acinar and islet cells of pancreas after partial hepatectomy in syrian golden hamsters. A significant nuclear labeling index of acinar cells was observed between 48 and 84 h and reached control levels by 120 h. An increased labeling index of islet cells was also observed, however, this increase was not statistically significant. These results indicate growth factor(s) produced after partial hepatectomy is capable of inducing DNA synthesis in pancreas.     

DNA synthesis in exocrine and endocrine pancreas after partial hepatectomy in Syrian golden hamsters

Summary ³H-thymidine autoradiography showed an enhanced DNA synthesis, in acinar and islet cells of pancreas after partial hepatectomy in syrian golden hamsters. A significant nuclear labeling index of acinar cells was observed between 48 and 84 h and reached control levels by 120 h. An increased labeling index of islet cells was also observed, however, this increase was not statistically significant. These results indicate growth factor(s) produced after partial hepatectomy is capable of inducing DNA synthesis in pancreas.This work is supported by NIH grant CA 36043.     

Effects of butyrate and insulin and their interaction on the DNA synthesis of rumen epithelial cells in culture

Rumen epithelial cells (REC) were incubated in the presence of various concentrations of butyrate or insulin or with both of them, to obtain information on their effect on the DNA synthesis of cultured cells. The 24-h values of 3H-thymidine incorporation into cellular DNA were measured in the presence of butyrate, insulin or butyrate plus insulin. While butyrate reduced DNA synthesis, insulin produced an increase over the control. Combined butyrate plus insulin treatment influenced the incorporation of label in accordance with the relative proportion of these two substances.     

Effects of butyrate and insulin and their interaction on the DNA synthesis of rumen epithelial cells in culture

Summary Rumen epithelial cells (REC) were incubated in the presence of various concentrations of butyrate or insulin or with both of them, to obtain information on their effect on the DNA synthesis of cultured cells. The 24-h values of³H-thymidine incorporation into cellular DNA were measured in the presence of butyrate, insulin or butyrate plus insulin. While butyrate reduced DNA synthesis, insulin produced an increase over the control. Combined butyrate plus insulin treatment influenced the incorporation of label in accordance with the relative proportion of these two substances.     

The growth responses of hamster chondrocytes,dermal fibroblasts and embryo cells to whole blood serum and plasma-derived serum

Summary Autoradiographic studies with³H-thymidine demonstrated that the growth responses of hamster chondrocytes, dermal fibroblasts and embryo cells, respectively, differed in media containing whole blood serum (WBS) and plasmaderived serum (PDS). Dermal fibroblasts seemed to require a growth factor from platelets for growth, but chondrocytes did not. Embryo cells showed an intermediate pattern of growth response to this factor.This work was supported by a Grant-in-Aid for Cancer Research from the Ministry of Education, Science and Culture and the Ministry of Health and Welfare of Japan.We thank Miss M. Tanaka and Miss K. Kawana for technical assistance.     

Effect of heat-labile enterotoxin (LT) produced byEscherichia coli on in vitro cell proliferation

Summary Filtrates fromE. coli H10407 cultures, giving a positive response for heat-labile enterotoxin (LT) in the Y-1 cell test, show an inhibitory activity both on³H-thymidine uptake by Ehrlich ascites cells and on granulocytic-macrophagic precursors (CFU-C) in murine bone marrow.Acknowledgments. We gratefully acknowledge the expert technical assistance of L. Basso and A. Gerosa of Department of Pathology, Hospital of Desio.     

Peritoneal macrophages from adjuvant arthritic rats enhance tumour cell growth in vitro

Summary Peritoneal macrophages from rats with adjuvant arthritis enhance the incorporation of³H-thymidine in 2 tumour cell lines in vitro. Maximal enhancement is found during the development of the secondary lesions, and it is suggested that the immunologic commitment of the macrophages could interfere with their regulation of tumour cell proliferation in vivo.Acknowledgments. The authors thank Drs P.F. Engel and M.P. Andreasen from the Finsen Institute, Copenhagen, for their gift of tumour cells and Ms E. Greve Petersen, Ms B. Hasselriis and Ms F. Norris for excellent technical assistance.