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Biomedical subjects

K Toyoshima

Publications and source records attributed to K Toyoshima.

At least 307 records · Page 17Linked to original sources
PubMed1979

The occurrence of ciliated and mucous cells in the peripapillary trench of the rat tongue.

Ciliated cells surrounded by mucous cells were found near the base of the peripapillary trench of the rat circumvallate papilla. The ciliated cells occurred singly or in small groups. Each cilium showed the nin plus two filament pattern characteristic of motile cilia. We consider that these cells function in wetting the taste pores, circulating saliva containing tastants and removal of debris from the papillary trench.

Animals↗
PubMed1979

Purification of viral proteins from avian sarcoma virus QV2.

A procedure was established whereby most of the major viral proteins were isolated to apparent homogeneity in biologically and immunologically active forms from a single batch of avian sarcoma virus QV2. For the initial step of purification, gently disrupted virions were fractionated by CsCl centrifugation into envelope proteins, RNA-dependent DNA polymerase, and viral core proteins. Further purification of envelope glycoproteins and DNA polymerase was performed by affinity chromatography on agarose columns cross-linked with plant lectins and poly(C), respectively. On the other hand, core proteins were fractionated by a combination of gel filtration and ion-exchange column chromatography into components p27, p19, and p15. The core protein p15 thus isolated retained proteolytic activity even after storage for 6 months. The present study also demonstrated that QV2 p19 is structurally altered from the corresponding protein of avian myeloblastosis virus (AMV), a reference avian leukosis-sarcoma virus having a well-characterized polypeptide composition.

DNA-Directed DNA Polymerase↗
PubMed1979

Selective replication of transformation-defective avian sarcoma virus mutants in duck embryo fibroblasts.

When an avian sarcoma virus (ASV), subgroup C Bratislava 77 (B77-C) was inoculated into duck embryo fibroblast cultures (DEF) at a m.o.i. of 0.02, its replication was retarded by about 3 days compared with that in chick embryo fibroblast cultures (CEF). A transformation-defective (td) mutant was isolated during this period of retardation. Unlike the sarcoma virus, this td mutant replicated in both DEF and CEF with no retardation, even at a low m.o.i. The subgroup C Prague strain of Rous sarcoma virus (PR-C), which can infect DEF, also replicated in DEF slower than its td mutant, tdPR-C, at a m.o.i. of 0.02.

Animals↗
PubMed1979

Heterogeneous RNA of the Prague strain of Rous sarcoma virus caused by undiluted passages.

The size of genomic RNA in PR-RSV A passaged in chick embryo fibroblasts (CEF) or quail embryo fibroblasts (QEF) was determined by gel electrophoresis. The results showed that 3 undiluted passages resulted in heterogeneity of RNA. The heterogeneity of the smaller incomplete RNAs in the virus stock was decreased by diluted passage or cloning, but RNA of the b subunit size and a subunit RNA of complete genome size were relatively stable. These heterogeneous RNAs were characterized by hybridization analysis. The RNAs from 4 peaks hybridized with both cDNAtotal and cDNAsrc to appreciable extents, indicating that they were derived from viral RNA and that at least some of them contained the src sequence. This finding and the failure to isolate a td mutant from the undiluted-passaged virus stock or from some subclones that had a and b subunits of RNA indicate that the td virus was only a minor constituent of the incomplete virus population caused by undiluted passages. Some viruses with incomplete RNA in the virus stock could produce foci with the aid of td B77 or RAV-60. The emergence of rd viruses by undiluted passages was indicated.

Animals↗
PubMed1979

Establishment of cell lines from the wild rodent Millardia meltada and tests for endogenous virus.

Four cell lines were established from the wild rodent, Millardia meltada; an untransformed cell line (MM-D), a non-producer (NP) cell line transformed with murine sarcoma virus (MM-CL4), and SV40-transformed cell lines (MM-8 MM-663). MM-D is epithelioid and contact-inhibited, whereas MM-CL4, MM-8, and MM-663 are fibroblastic and grow piling up. No endogenous virus was induced in Millardia cell lines by a long-term culture with various inducers. Millardia cell DNA has no nucleotide sequence homology with cDNA of either murine leukemia virus or rat endogenous virus.

Animals↗
PubMed1977

Adenylate cyclase activity and the cAMP level are not directly correlated with transformation by avian sarcoma viruses.

The adenylate cyclase activity was measured in chick embryo fibroblasts (CEF) infected with temperature-sensitive mutants (ts) of avian sarcoma virus (ASV). When CEF transformed with a (ts) mutant at 36 degrees C were incubated at the non-permissive temperature (41 degrees C), recovery from the low adenylate cyclase activity detectable in the transformed state was slower than the disappearance of signs of morphological transformation. After a downward shift of the temperature the activity decreased and this change was also slower than the alteration of cell morphology. The affinity of the enzyme system for ATP also changed after, and not during, morphological alteration. No significant difference was observed between the cAMP levels in ASV-transformed and non-infected CEF. These findings are consistent with the idea that adenylate cyclase is not involved in cell transformation and that the change in its activity is secondary to cell transformation.

Adenylyl Cyclases↗
PubMed1977

Five cases of absence of iodide concentrating mechanism.

Five cases, 2 males and 3 females, with absence of iodide concentrating mechanism are reported. Three of the five subjects are siblings and the eldest sister has no symptom to account for the cretinism. All 5 cases have improved clinically following the administration of potassium iodide and 4 cases are still in a euthyroid state without any adverse effects during a half to more than 4 years. This study suggests that the absence of iodide concentrating mechanism might be erroneously diagnosed as athyroidal cretinism or adolescent non-toxic diffuse goitre, and may at times not show any clinical symptoms.

Adolescent↗
PubMed1976

Animal experiments on thiamine avitaminosis and cerebral function.

Before industrial production of thiamine becam possible, among many beriberi patients some showed symptoms of encephalopathy, the cerebral form of the disease. In this animal experiment, thiamine-deficient rats showed failure or blocking of the operant behavior in the maze box, pole climbing box and shuttle box, indicating orientation disturbance and defective memory. This Wernicke's syndrome-like sign dramatically disappeared by treatment with thiamine. Potentiated narcosis with thiopental or alcohol induced in thiamine-deficient rats and mice was readily reversible by thiamine administration. These phenomena are associated with thiamine content of the brain and are found long before histopathological changes in the brain of deficient animals. It is easily surmised that thiamine deficiency in the brain may block the brain metabolism and subsequently cause changes in any chemical substances in the brain, refracting on biophysical phenomenon, such as EEG. However, in the present study, generally speaking, no meaningful results concerning these points were obtained.

Animals↗
PubMed1976

Histological comparison of the growth of rat bladder carcinoma R-4909 observed for two years in vitro and in vivo.

A transplantable bladder tumor (Chapman R-4909) of the rat, when first received in our laboratory, grew with a complex histopathology. The predominant component was transitional cell carcinoma, but there were foci of keratinization, including pearl formation, and foci of a less well-defined cystic appearance. We report here observations made during the first 2 years of an ongoing study on the divergent histopathology of R-4909 under several conditions of propagation. During the entire period, the tumor has been maintained by serial passage in rats (Fischer 344) and by serial passage in vitro. At intervals, cells of the tissue culture series were inoculated into rats to compare the histopathology of animal- and culture-passed strains. We obtained several clones from the stock cultures and these also were maintained continuously in vitro. At intervals, cells from two of these lineages, clone A and clone B, were inoculated into rats. After 2 years, cells maintained in stock culture, on injection into new rats, produced growths similar to the original in that all three epithelial patterns, transitional, squamous, and adenomatous, were perpetuated. In contrast, the tumor passed exclusively in vivo lost its squamous component completely. It became anaplastic, with tissue architecture almost entirely adenomatous and cystic. Unlike the stock tissue culture line, the clonal isolates following prolonged culture produced adenomatous tumors only. In a related preliminary study, we inoculated into rats R-4909 cells that had been cultivated for up to 2 months under aerobic and anaerobic conditions. Tumors grew in most of the animals, and those of the aerobic group were more cystic than the others.

Animals↗
PubMed1976

Conditions of cultivation required for the formation of hemicysts in vitro by rat bladder carcinoma R-4909.

Rat urinary bladder carcinoma R-4909 grew readily in vitro. In areas where saturation density occurred in the cultures, occasional hemicysts were observed. A modification of technique producing "packed cultures" resulted in the appearance of greater numbers of hemicysts. Four clonal isolates of R-4909 were also studied in packed culture. Clone B formed hemicysts in abundance. Clone D produced occasional hemicysts similar to the parent stock line. No hemicysts were seen in cultures of clone A or clone C. The number of hemicysts formed by clone B in packed culture was responsive to the ratio between cell number and volume of medium, to serum concentration in the medium, and to pH of the medium. The last was of particular interest since a pH of 7.8 enhanced and a pH of 6.6 inhibited hemicyst formation. The effects were all reversible. On scanning electron microscopy, we found well-developed cell membrane structures between contiguous cells. In media with sufficient serum for hemicyst formation, the articulations between cells were prominent. With low serum concentrations, hemicysts did not form and the intercellular articulations were less distinct. We interpret the formation of hemicysts as an expression of fluid transport by epithelia, a function that requires a constellation of differentiated characteristics within cells and in their level of integrated association.

Animals↗
PubMed1975

Vitamin A inhibition of keratinization in rat urinary bladder cancer cell line Nara Bladder Tumor No. 2 in meniscus gradient culture.

The Nara Bladder Tumor No. 2 cell line, established from a urinary bladder carcinoma in the Wistar rat, formed keratinizing cells and multicellular pearls in meniscus gradient culture when fed with a medium of 15 or 30% fetal calf serum in Eagle's minimal essential medium. Confluent monolayer cultures were first prepared with the tubes in conventional horizontal position. When cultures were then changed to a vertical position, stratification, piling up, and aggregation of cells were observed in a few days at the aerobic end of the gradient. Keratinization appeared 1 week after the tubes were placed in vertical position. Squamous differentiation proceeded to the formation of keratin pearls, a phenomenon never observed so distinctly and in such abundance in horizontal culture. Supplements of vitamin A, as low as 1 IU/ml, added to the medium did not inhibit piling up or aggregation but did prevent keratinization. Inhibition of keratinization by vitamin A was reversible. After vitamin A was removed from the medium, the cells in the aggregates progressed to keratinization.

Animals↗