Quantitative studies on in vitro transformation of hamster chondrocytes

Summary Hamster chondrocytes could be transformed in a quantitative assay system which used X-irradiated feeder layer cells. Morphological transformation occurred on addition of, 4NQO, but not in control cultures. Differentiation was classified into 3 types (good, poor and none); normal and transformed colonies contained similar proportions of the 3 types.This work was supported by a grant from the Ministry of Education, Science and Culture, Japan.We thank Miss M. Tanaka for her technical assistance.     

Immunochemical identity of dipeptidyl aminopeptidase IV from pig serum,liver, submaxillary gland and kidney

Summary The enzymes which were extracted by autodigestion from the microsomal fractions of the pig kidney, liver and submaxillary gland and from the serum showed an immunochemical identity by a double immunodiffusion test. But the kidney enzyme had a different pI-value from the pI-values of the enzymes of other organs.This investigation was supported by a grant from the Ministry of Education, Japan to K. M. F. We would like to thank Dr Toshiharu Nagatsu (Department of Life Chemistry, Graduate School at Nagatsuta, Tokyo Institute of Technology, Yokohama, Japan) for helpful suggestions, Mr Moritoshi Sato (Matsumoto Meat Inspection Station, Matsumoto, Japan) for their generous supply of pig organs and Ajinomoto Co. Inc., Tokyo, Japan, for the gift of Gly-Pro-p-nitroanilide tosylate. Technical assistance of Miss K. Yanagisawa is gratefully acknowledged.     

Reassociation of eukaryotic ribosomal subunits by a factor from rat ascites hepatoma cytosol

Summary Post-ribosomal supernatant extracts from Yoshida AH 130 ascites hepatoma cells promote the in vitro association of ribosomal subunits at low Mg²⁺ concentration. Comparable extracts from rat liver show, on the contrary, dissociation factor activity on ribosome monomers.The technical assistance of Miss M. Ravazzani and Miss L. Zingaretti is gratefully acknowledged.     

Serum cholinesterase: Function in lipoprotein metabolism

Summary Human serum beta-lipoproteins, isolated by percipitation with heparin-calcium mixture, showed cholinesterase activity. The enzyme activity was almost proportional to the lipoprotein concentration. Rats, treated with neostigmine, a cholinesterase inhibitor, showed a significant decrease in serum beta-lipoprotein and in the incorporation of H³-lysine into the lipoprotein compared to untreated controls. The decreased incorporation of H³-lysine into beta-lipoprotein was associated with increased labelling of alpha-lipoprotein. There was no significant difference in the labelling of pre-beta-lipoprotein. We propose that LDL is formed from VLDL in the presence of cholinesterase.We thank Dr C. J. Hutton for helpful discussions, Miss Patricia Fontaine for technical assistance, and Miss Patricia Candow and Mrs Barbara English for secretarial work. Supported by the Canadian Heart Foundation.     

Ocular involvement in hamsters transplanted with a human leukemic T-cell line

Summary A leukemic T-cell line (TALL-1) was serially transplanted for 5 passages into newborn hamsters treated with antilymphocyte serum. This cell line was derived from a leukemic patient with clinical evidence of ocular involvement. I.p. implantation of 1–3×10⁷ cells resulted in disseminated growth of tumors in all 15 recipients after 23–41 days and 8 of them showed leukemic infiltration of the uveal tract of one or both eyes.Supported by a Cancer Research Grant from the Ministry of Health and Welfare of Japan.     

Radioimmunoassay of some hormones simultaneously measured in serum and breast cyst fluid

Summary Blood and breast cyst fluid were drawn simultaneously for hormonal determination. There was no difference between serum and cyst fluid values of PRL and TSH. A significant difference was noted for LH (p<0.01) and FSH (p<0.05), serum concentrations being higher than cyst fluid concentrations.The authors are indebted to Miss J. Meister, E. Dullaert and J. Beck for their skillful technical help. We are also indebted to the National Institutes of Health, NIAMDD and the World Health Organization, International Laboratory for Biological Standards.     

The chemokinetic effect of serum albumin

Summary Experiments performed by means of time lapse cinematography or the filter technique show that human serum albumin has marked chemokinetic effects on neutrophil cultured in Gey's solution. The average speed of the cells, as well as the proportion of neutrophils showing locomotion, is increased. Enhanced locomotion correlates with decreased attachment to the substratum as determined by morphological and functional criteria.We thank Mrs R. Graf and Miss M. Schuster for technical assistance. This work was supported by the Swiss National Science Fondation.     

Development of the maximum isometric force at short sarcomere lengths in calcium-activated muscle myofibrils

Summary Studies on the sarcomere length-force relation in Ca⁺⁺-activated vertebrate muscle myofibrils indicate that the maximum isometric force can be generated even at sarcomere lengths around 1 m, indicating that the ascending limb of the sarcomere length-force relation is virtually absent.We thank Miss S. Gomi for her technical assistance. This work was supported by the grant (No. 587028) form the Ministry of Education, Science and Culture of Japan.     

The effect of Valium® anaesthesia on the radiosensitivity of the skin of the mouse foot

Summary Valium^® anaesthesia significantly reduces the effect of large single doses of X-rays on the mouse foot skin as compared with Nembutal^® anaesthesia. The radioprotective action of Valium may be attributed to a direct effect on the cells of the skin.Supported by the Swiss National Science Foundation (Grant no. 3.682-0.75).Acknowledgments. The authors wish to thank Miss F.T. Josuran, Miss U. Schärer and Mr P.P. Binz for their excellent technical assistance with the experiments.     

Effect of temperature on in vitro proliferative activity of human umbilical vein endothelial cells

Human umbilical vein endothelial cells, skin fibroblasts, and retinal pigment epithelial cells are cultivated in medium supplemented with 15 to 20% serum in our laboratory. The effects of various incubation temperatures on the proliferation of these cells was examined. Our study shows that the mitogenic response of the endothelial cells to a change of temperature differed markedly from that of the fibroblasts and epithelial cells. Cultivation of human umbilical vein endothelial at 37°C required seeding densities as high as 1–2×10⁴ cells/cm², and yet resulted in a low growth rate and premature senescence. However, under the same culture conditions, but at 33°C, the proliferative capacity of these endothelial cells was potentiated. The results were striking; at 33°C the cells grew actively and the life span was extended. The number of cumulative population doublings increased fourfold compared with that for the same cells cultivated at 37°C. The inoculum size could be reduced, since at 33°C the endothelial cells were able to replicate at seeding densities as low as 20 cells/cm². The cells serially subcultured at 33°C retained morphological features and specific immunological markers of endothelial cells.     

Vitamin A and tumor immunity

Summary Intraperitoneal administration of vitamin A into the BALB/c mice inoculated with a syngeneic fibrosarcoma, Meth A, caused a remarkable augmentation of tumor rejection. A cell-depletion technique revealed that the primary effector cells responsible for the augmented rejection were Thy-1 positive, Lyt-1 negative, Lyt-2 positive lymphocytes, suggesting the involvement of cytotoxic lymphocytes.This work was supported in part by a Grant-in-Aid for scientific research from the Ministry of Education, Science and Culture, Japan, and in part by a Grant-in-Aid for cancer research from the Fukuoka Cancer Society, Japan.We thank Mr M. Fujiki and Miss A. Maeda for excellent technical assistance.     

Sodium and calcium action potentials in human anterior pituitary cells

Summary Human anterior pituitary cells derived from a somatotropin-secreting adenoma were capable of generating action potentials with Ca²⁺ and tetrodotoxin-sensitive Na⁺ components. A major fraction of the action current was carried by Na ions.We wish to thank Dr O. Sand for correcting the English and Miss Michiko Takano for technical assistance. We also acknowledge the collaboration of Dr S. Miyazaki in the electron microscope.     

A simplified method for reading hemagglutinations on a flat-bottom microtitration plate in the mouse H-2 assay

Summary Kaliss' method for determining hemagglutination titer of mouse alloantiserum was modified to a simpler form. It became possible to read the hemagglutination directly on a flat-bottom microtitration plate using an inverted type microscope. Sensitivity of the modified method was almost the same as that of the original one. This method seems to be useful especially for the larger scale assay of H-2 specificities.Contribution from the National Institute of Genetics. Supported in part by grants-in-aid (No. 111510, 111504, 112105) from the Ministry of Education, Culture and Science, Japan.Acknowledgments. The excellent technical assistance provided by Miss M. Kuranou, Mr K. Sakakibara and Miss M. Tsuyuki is gratefully acknowledged.     

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.     

Possible involvement of protein kinase C in the stimulation of amino acid transport by phorbol ester,platelet-derived growth factor and A23187 in Swiss 3T3 cells

Summary Stimulation of amino acid transport induced by phorbol-12, 13-dibutyrate, platelet-derived growth factor or A23187 was not observed in cells lacking protein kinase C. On the other hand, stimulation of transport by epidermal growth factor or insulin was not affected. These results suggested that the stimulation of amino acid transport is mediated by at least two separate pathways.This work was supported in part by Grants-in-Aid for Scientific Research from the Ministry of Education, Science and Culture, and the Ministry of Health and Welfare of Japan.     

Mg2+-ATPase defective mutant ofEscherichia coli and thiamine transport

Summary Mg²⁺-ATPase deficient mutant ofEscherichia coli showed an evident dependency of thiamine uptake on the oxidative metabolism of glucose, whereas the parent strain did not. In both cells, this uptake was completely inhibited by H⁺ conductors.Acknowledgment. We are indebted to Miss M. Abe for her excellent technical assistance.     

Effect of cell proliferation on the condensation of X chromosomes in the form of Barr-bodies, in human 46 XX fibroblast cultures with different serum concentrations]

The frequency of Barr-bodies in cultivated 46 XX human fibroblasts considerably increases when in confluent monolayer cultures the cells no longer divide. Or, independently of cell contact, when the cells are grown in medium with low serum content, which will slow down or entirely arrest further growth. The frequency of Barr-bodies again diminishes when after the administration of culture medium with sufficient serum concentration, the cells start growing again, indicating that the condensation of the X chromosome is reversible under control of the cell proliferation.     

Preferential neurotoxicity of pentobarbital on nerve and glial cells in culture

Summary The effect of pentobarbital was studied in a mixed population of nerve and glial cells dissociated from brains of 7-day chick embryos and maintained in culture. Pentobarbital-Na was added in various concentrations ranging from 5×10^–5 M to 1×10^–3 M. The neuronal density was monitored by counting of neurons, neuronal identity was established by staining for Nissl Bodies and acetylcholinesterase. Over a culture period of 3 weeks, it was found that the barbiturate exerts a preferential dose-dependent cytotoxic effect on neurons.The expert technical assistance of Miss A. Wolf is appreciated. This work was supported by grant 6-74-27, INSERM (Physiologie et Pathologie du Développement Nerveux).     

The effect of pinealectomy on serum progesterone and oestradiol levels during the last stage of pregnancy in rats

Summary Pinealectomy leads to significantly higher levels of progesterone (on days 19 and 20 of gestation) and oestradiol (on days 21 and 22) in the serum of pregnant rats. These results indicate that during the last phase of pregnancy the pineal gland may be modifying the levels of gonadal hormones, although not affecting the sequence of the physiological events.Acknowledgment. The authors wish to thank Miss Ute Schmidt for her invaluable technical assistance.     

Specific phosphorylation of a calf serum protein by a kinase from the cell surface]

A protein of molecular weight approximately 200,000, which exists in trace amounts in calf serum, is specifically phosphorylated by an enzyme located at the surface of cultured cells. The emzymatic reaction utilizes ATP, is enhanced by Mg++ and Zn++ ions, and is not dependent on cyclic AMP. This kinase activity is associated with normal growing fibroblasts but disappears when they are contact-inhibited. It remains high, however, in transformed and malignant cells, whatever their growth state.