The identification of the human cultured cell lines was performed by the method of the DNA-polymorphism typing assay based on a polymerase chain reaction (PCR). We have examined eight human cell lines given from Japanese Cancer Research Resources Bank (A-549, HeLa, IMR-32, HT-1080, RD, PA-1, PC-3 and RERF-LC-MS). Each locus of D1S80 and HLA DQa was amplified by PCR. Alleles of the D1S80 were observed as silver-stained bands after electrophoresis on a polyacrylamide gel, and the HLA DQa product was screened onto strips dotted the sequence-specific DNA probes by a reverse dot-blot hybridization. Each cell line was distinct independently in the types of D1S80-VNTR and HLA DQα sequences.
The cumulative power of discrimination (PD) for D1S80 and HLA DQα types was calculated to be 0.996-0.998 from the racial population study. The superiority of this method to the fingerprinting one would be its reproducible results and shortening of process time. The system used here for the detection of D1S80 and HLA DQα alleles would be one of the standards to establish cell libraries.

View full abstract

The periodontal ligament is a typical noncalcified connective tissue that functions in tooth support and lies between cementum and alveolar bone which are mineralized tissues. This tissue is involved in the remodeling processes associated with the development of periodontium, tissue regeneration and physical stresses such as occlusion and mastication. The cells derived from periodontal ligament were characterized with respect to the osteoblastic phenotypes which demonstrated the expression of bone type alkaline phosphatase (ALPase) and bone proteins, the cellular responses of calcium regulatory hormones such as 1,25(OH)₂D₃ and parathyroid hormone (PTH), and the ability to form mineralized-like nodules. The effects of mechanical stress on the cellular processes of human periodontal ligament fibroblast-like cells (HPLF) were investigated in relation to the regulation of cell proliferation and differentiation. The periodontal ligament may comprise a heterogeneous cell linage which is a renewal cell system in remodeling and regeneration.

View full abstract

Viral infection often causes the death of host cells, and this phenomenon, called the cytopathic effect, has been thought to occur when the replicated virus particles leave the cells. However, some viruses appear to bring about the prolonged survival of host cells. Now we know that these phenomena involve the regulation of apoptosis; the cytopathic effect reflects the induction of host cell apoptosis and the inhibition of apoptosis causes host cells to survive. These events apparently require the function of both viral and cellular genes, which encode either apoptosis-inducing or -inhibiting proteins. The prolonged survival of the host cell is presumably beneficial for the virus to produce more progenitors, whereas the earlier death of virus-infected cells could result in protecting the organism from viral diseases. It is thus postulated that the induction of apoptosis is a self-defense mechanism of the host, while the inhibition of apoptosis is a consequence of viral action countering the host response. In this review, the mechanism underlying the regulation of apoptosis in virus-infected cells is outlined and the implications of the findings are discussed.

View full abstract

Apoptosis is a mechanism for eliminating unwanted cells from the cell community of multicellular organisms. Abnormalities in the regulation of apoptosis may play a part in the aetiology of cancer, autoimmune diseases, AIDS, degenerative nerve diseases and malformation. One of the hallmarks of apoptosis is the enzymatic cleavage of genomic DNA into nucleosomal oligomers. The identification of an endonuclease responsible for apoptosis might help to explain how this cell suicide is regulated and why DNA is cleaved. Here, we found that ytype of DNase was retained in apoptotic rat thymocyte nuclei. The mode of DNA cleavage,3'-hydroxyl (OH)/5'-phosphoryl (P) ends, by homogeneously purified DNase γ(Mr=33 kDa) and its Zn²⁺ sensitivity mach those observed in apoptosis in thymocytes induced by irradiation or glucocorticoid treatment, indicating that this endonuclease is a central component of the thymic apoptosis machinery.

View full abstract

Ttransfection efficiency for permanent transfectants was improved in 3Y1 and its derivative cell lines. Transfection efficiency of various cell cycle ts mutant clones and an adenovirus transformed clone showed transfection efficiency at 10^-4-10^-5 and 10^-5-10^-6, respectively, by calcium phosphate precipitation method including various modifications. The efficiency was improved up to 10^-3 by electroporation in all these clones as well as parental 3Y1.

View full abstract