Search PubMed⌕ Search

Biomedical subjects

S Tajima

Publications and source records attributed to S Tajima.

At least 145 records · Page 8Linked to original sources
PubMed1998

Function and conformation of wild-type p53 protein are influenced by mutations in bovine leukemia virus-induced B-cell lymphosarcoma.

The mutations of the p53 gene previously represented one of several genetic changes involved in the development of bovine leukemia virus (BLV)-induced lymphosarcoma, while the effects of these mutations on the function of p53 are unknown. We identified four mutations of p53 gene in BLV-infected cattle with lymphosarcoma and demonstrated clearly the existence of two functionally distinct groups of mutants: (i) the mutant forms with substitutions at codons 241 and 242, which were mapped within an evolutionally conserved region and corresponded to the human "hot-spot" mutations, had completely lost the capacities for transactivation and growth suppression and gained transdominant repression activity in p53-null SAOS-2 cells; and (ii) the mutations at codons 206 and 207 were located outside the evolutionally conserved regions. These mutants partially retained the capacity for transactivation and growth suppression and failed to inhibit the transactivation activity of coexpressed wild-type p53, instead showing an enhancement of this activity. In addition, protein analysis using an antibody specific for the mutant form revealed that the mutations at codons 206 and 242 induced a "mutant" conformation of the bovine p53 proteins. Collectively, these results show that mutations of p53 gene in BLV-infected cattle with lymphosarcoma can potentially alter its physiological function and may play an important role in BLV-induced leukemogenesis.

Animals↗
PubMed1998

Acquisition of secretion of transforming growth factor-beta 1 leads to autonomous suppression of scavenger receptor activity in a monocyte-macrophage cell line, THP-1.

Macrophage cells derived from the human monocytic leukemia cell line, THP-1, accumulate esterified cholesterol when cultivated in the presence of acetylated low density lipoprotein (Ac-LDL) through scavenger receptors (ScR). In the present study, we isolated a subtype of THP-1 cells that failed to accumulate esterified cholesterol when cultivated in the presence of Ac-LDL. The cells had negligible amounts of cell association and degradation of Ac-LDL compared with the parent THP-1 cells. The subtype THP-1 cells did not express ScR mRNA as well as that of lipoprotein lipase. In contrast, the expression of apolipoprotein E mRNA was greater than that found in parent THP-1 cells. The culture medium of subtype THP-1 cells treated with 12-O-tetradecanoylphorbol-13-acetate inhibited the uptake of Ac-LDL and the expression of ScR in parent THP-1 cells. After a 48-h incubation in the culture medium containing 12-O-tetradecanoylphorbol-13-acetate, the culture medium of differentiated subtype THP-1 cells contained 6.9 ng/ml transforming growth factor (TGF)-beta 1, while that of parent THP-1 cells secreted below detection level, which was less than 3 ng/ml. This inhibitory effect of the conditioned medium on the expression of ScR in parent THP-1 cells was abolished by pretreatment of the culture medium with anti-TGF-beta 1 antibodies. Parent THP-1 cells expressed as much TGF-beta 1 mRNA as sTHP-1 cells after stimulation of differentiation. Although the precursor forms of TGF-beta 1 that were synthesized in both parent and subtype THP-1 cells were of similar size and were expressed at similar levels, latent TGF-beta 1-binding protein, which is necessary for the secretion of TGF-beta 1, could only be co-immunoprecipitated with anti-TGF-beta 1 antibody from subtype THP-1 cells. This suggests that subtype THP-1 cells secrete TGF-beta 1 into the medium by forming a functional complex with the latent TGF-beta 1-binding protein. We conclude that subtype THP-1 cells could not take up Ac-LDL because ScR was inhibited (leading to a loss of function) caused by the secreted TGF-beta 1.

Carrier Proteins↗
PubMed1998

A novel point mutation in a splice acceptor site of intron 1 of the human low density lipoprotein receptor gene which causes severe hypercholesterolemia: an unexpected absence of exon skipping. Mutations in brief no. 139. Online.

Familial hypercholesterolemia (FH) is a genetic disorder caused by mutations in the low density lipoprotein (LDL)-receptor gene. We found a new mutation in the splice acceptor site of intron 1 of the LDL receptor gene, which is designated as 68-1 G->C according to the nomenclature suggested by Beaudet and Tsui (1993), in a Japanese FH homozygote. She was born from consanguineous marriage and has this mutation as a true homozygous form. Her cultured fibroblasts showed no LDL receptor protein synthesis. This mutation caused activation of a cryptic splice acceptor side in the downstream exon 2, leading to frameshift and appearance of premature in-frame stop codon. The mutation was detected by Dde I restriction enzyme. The identical mutation was not found among 24 patients with homozygous and 120 patients with heterozygous FH. The mutation was very rare among the Japanese population.

Alternative Splicing↗
PubMed1998

Decrease in p53 protein in cultured cardinal ligament fibroblasts from patients with prolapsus uteri.

The authors examined the growth response of cardinal ligamental fibroblasts derived from patients with prolapsus uteri (HPLiF) and compared it with the response of those from control subjects (HCLiF). The growth rate during the logarithmic growth phase was not different between HPLiF and HCLiF, while the cell density at confluence (saturation density) was significantly higher in HPLiF than in HCLiF. When added alone, platelet-derived growth factor (PDGF), insulin-like growth factor-I (IGF-I), and epidermal growth factor (EGF) produced minimal effects on DNA synthesis in HCLiF. The simultaneous addition of PDGF, IGF-I and EGF synergistically stimulated the DNA synthesis. In contrast, PDGF alone was able to initiate DNA synthesis in HPLiF. The combination of PDGF, IGF-I, and EGF significantly stimulated the DNA synthesis of HPLiF compared with HCLiF. p53 protein and p53 gene transcripts decreased by 50% in HPLiF. The anti-WAF1 antibody reacted intensely with a 21-kDa protein in the homogenates of control fibroblasts, while the immunoreactive band in prolapsus fibroblasts was clearly reduced. These results indicate that the higher proliferative activity at near confluency in prolapsus fibroblasts may result from the decreased expression of p53 protein and p53 mRNA followed by the decrease in p21 protein. Furthermore, the failure of cells to enter quiescence may lead to a decrease in the synthesis and deposition of elastin and thus may contribute to the loss of supportive function in uterine connective tissues.

Aged↗
PubMed1998

Sulfatide protects rat skin flaps against ischemia-reperfusion injury.

Monoclonal antibodies to adhesion molecules have been used in many trials to prevent ischemia-reperfusion injury. Sulfatide reacts strongly with P- and L-selectin, which play an important role in the initiation of neutrophil-endothelial interactions occurring in injured or inflamed tissues. The purpose of this study was to evaluate the effect of sulfatide on ischemia-reperfusion injury of the rat skin flap. Sulfatide was administered intravenously just before elevation of the right abdominal epigastric flap. The femoral artery and vein were clamped above and below the epigastric vessels for 10 or 11 h and then the clamp was released. Administration of sulfatide augmented significantly the flap area surviving in the 10-h ischemic model (7.18 +/- 0.47 cm2 versus control 5.15 +/- 0.39 cm2. P = 0.01). In the 11-h ischemic model the area was 4.59 +/- 0. 36 cm2 versus control 1.73 +/- 0.31 cm2 (P = 0.001). The ATP levels in the flap gradually increased after release of the clamp in the rat administered sulfatide, and the increase was significant at 48 h (P = 0.006). Histological examination 48 h after surgery showed greater leukocyte invasion into the control flap than into the flap of the rat administered sulfatide. Myeloperoxidase activity was significantly reduced 48 h after reperfusion in the 11-h ischemic model. This study indicates that sulfatide has a significant protective effect against ischemia and reperfusion in rat epigastric flaps.

Adenosine Triphosphate↗
PubMed1998

In vitro degradation of tropoelastin by reactive oxygen species.

The effects of reactive oxygen species (ROS) on elastin molecules (tropoelastin) were studied in vitro. ROS generated by ultraviolet A and hematoporphyrin rapidly degraded tropoelastin within 5 min. Their degradative activity was inhibited by the addition of NaN3. Treatment of tropoelastin with copper sulfate/ascorbic acid resulted in degradation of tropoelastin producing fragments of molecular weight 45, 30 and 10 kDa within 30 min. The degradation of tropoelastin was partially blocked by the addition of mannitol. ROS induced by the xanthine/xanthine oxidase system also degraded tropoelastin within 6 h. The degradation was blocked by catalase but not by superoxide dismutase (SOD). ROS generated by copper-ascorbate seems to be unique in that it cleaves relatively specific sites of the tropoelastin molecule. Thus ROS may play a degradative role in elastin metabolism which may cause the elastolytic changes or the deposition of fragmented elastic fibers in photoaged skin or age-related elastolytic disorders.

Ascorbic Acid↗
PubMed1998

Glycosaminoglycan and collagen distribution in the developing human vitreous.

BACKGROUND: We determined the distribution of glycosaminoglycans and collagens in the developing human vitreous. METHODS: Eighty human eyes from 5 gestational weeks to 2 postnatal years of age were used. Glycosaminoglycan components were determined by enzyme digestion with hyaluronidase or chondroitinase AC and ABC and immunohistochemistry for chondroitin, chondroitin-4-sulfate, chondroitin-6-sulfate, and dermatan sulfate. Collagen distribution was determined by immunohistochemistry for types I, II, and III collagens. RESULTS: Enzyme digestion showed that throughout development hyaluronic acid is the main glycosaminoglycan in the vitreous and in the extraocular space at 5-7 gestational weeks. Both areas were filled with mesenchymal cells. Immunohistochemistry showed chondroitin-6-sulfate in the vitreous between 6 and 40 gestational weeks, and chondroitin-4-sulfate between 12 and 40 gestational weeks. Hyaluronic acid and chondroitin sulfate appeared in the retina and around the hyaloid vessels at 12-40 weeks. Immunohistochemistry showed type III collagen in the vitreous and around the mesenchymal cells at 5-7 weeks that was replaced by type II collagen after 8 weeks. CONCLUSIONS: Hyaluronic acid is the major glycosaminoglycan in the vitreous throughout development, except for the transient appearance of chondroitin sulfate at 6-40 gestational weeks. Type III is the main collagen in the early developing vitreous that converts to type II collagen at 8 weeks. The primary and secondary vitreous has the same components as these macromolecules. These vitreous glycosamino-glycans and collagens seem to be produced by mesenchymal cells at an early stage and by the retina and hyaloid vessels during middle and late development.

Adolescent↗
PubMed1998

Pseudoxanthoma elasticum-like papillary dermal elastolysis: report of four Japanese cases and an immunohistochemical study of elastin and fibrillin-1.

We report four patients with pseudoxanthoma elasticum-like papillary dermal elastolysis (PDE). Multiple small papules on the neck, clinically resembling pseudoxanthoma elasticum, and loss of the elastic fibre network in the papillary dermis were found in each case. Immunohistochemical staining for elastin and fibrillin-1 in one patient demonstrated the disappearance of elastin and fibrillin-1 in the papillary dermis. Site-matched normal skins of the elderly showed intact elastin but a lack of fibrillin-1 in the papillary dermis. The younger normal skins revealed intact elastin and fibrillin-1. The results suggest that fibrillin-1 is absent from the papillary dermis of the normal-appearing neck skin of the elderly and that the primary defect in PDE may be in elastin rather than in fibrillin-1.

Adult↗
PubMed1998

Expression of the alpha1-alpha6 collagen IV chains in the dermoepidermal junction during human foetal skin development: temporal and spatial expression of the alpha4 collagen IV chain in an early stage of development.

To study the expression of the alpha1-alpha6 chains of type IV collagen in the dermoepidermal junction (DEJ) during human foetal skin development, human foetal (10 and 20 weeks of gestation) and adult skin was immunostained with specific monoclonal antibodies to the alpha1-alpha6 chains of type IV collagen. Intense expression of the alpha4 chain and weak expression of the alpha2 and alpha6 chains were observed in the DEJ of 10 weeks gestational skin. In contrast, the alpha1, alpha2, alpha5 and alpha6 chains were detected in the DEJ of 20 weeks gestational and adult skin. Preferential expression of alpha4 during the early phase of development (10 weeks of gestation) may suggest a chain-specific regulatory mechanism for type IV collagen expression and its potential role in DEJ formation during development.

Adult↗
PubMed1998

Surgical treatment of distal cervical internal carotid artery aneurysm.

We report on a 55-year-old male with an internal carotid artery aneurysm at the level of the second cervical vertebra. Since ant-coagulation therapy failed to prevent the ischemic attack, aneurysmectomy with arterial reconstruction was performed. Vertical mandibular osteotomy allowed a wide working space in deep operative field. This technique is considered to be useful in surgery for aneurysms of the extracranial distal internal carotid artery.

Aneurysm↗
PubMed1998

Regulation and function of DNA methylation in vertebrates.

In vertebrates, genomic DNA is often methylated at the 5th position of cytosine in the sequence of CpG, and this is the only chemical modification that genomic DNA of vertebrates allows under physiological conditions. During evolution, vertebrates acquired CpG methylation as a new tool for controlling gene expression in addition to the varieties of transcription factors. In mammals, the methylation pattern of genomic DNA is erased and reset in germ line and at the early stage of embryogenesis. Maintenance-type methylation activity ensures clonal transmission of the lineage-specific methylation pattern in somatic cells. The methylation pattern is dynamic and changes during cell differentiation. Prior to the expression of tissue-specific genes, specific sites of the promoters are demethylated. In general, the methylation of a gene suppresses its expression. However, not much is known about the mechanisms that regulate the methylation state and the gene expression by DNA methylation.

Amino Acid Sequence↗
PubMed1998

Antihypertensive activity and pharmacokinetics of KD3-671, a nonpeptide AT1-receptor antagonist, in renal hypertensive dogs.

The antihypertensive activity and pharmacokinetics of KD3-671 (previously named KT3-671), a nonpeptide AT1-receptor antagonist, were investigated in renal hypertensive dogs with normal or high plasma renin activity (PRA). A single administration of KD3-671 at 3 and 10 mg/kg, p.o., to the hypertensive dogs with high PRA dose-dependently reduced mean blood pressure (MBP), which was not correlated with plasma KD3-671 concentration. Significant increases in PRA and plasma angiotensin (Ang) II occurred 2 h after KD3-671 dosing. Enalapril at 3 mg/kg, p.o., also reduced MBP. Neither KD3-671 nor enalapril affected heart rate. When given orally once a day for 29 days to the hypertensive dogs with normal PRA, KD3-671 at 3 and 10 mg/kg/day dose-dependently reduced MBP, which was smaller than that in the dogs with high PRA. This was the case for enalapril. The hypotension induced by the first dose of KD3-671 or enalapril was consistently observed after doses 8, 15, 22, and 29. After cessation of repeated dosing, no rebound phenomenon in MBP was observed. Pharmacokinetic parameters of KD3-671 were not influenced by repeated dosing. KD3-671 markedly increased both PRA and plasma Ang II concentration at 2 h after dosing. These results suggest that KD3-671 may be useful for the treatment of hypertension.

Aldosterone↗
PubMed1998

Cathepsin D expression in skin metastasis of breast cancer.

Cathepsin D, an aspartic proteinase, correlates with invasion and metastasis in breast cancer and with poor prognosis. In the present study, we examined the immunohistological expression of cathepsin D in both primary (5 cases) and skin-metastatic breast cancers (13 cases) and compared it to those in gastric (2 cases) and lung (4 cases), and primary eccrine cancers (3 cases). All breast and gastric cancers were adenocarcinomas. The 2 gastric cancers were poorly differentiated, while the 4 lung cancers consisted of 2 poorly differentiated adenocarcinomas, 1 poorly differentiated large cell carcinoma, and 1 moderately to poorly differentiated squamous cell carcinoma. We also surveyed the immunohistological distribution of cathepsin B, carcinoembryonic antigen, gross cystic disease fluid protein-15, c-erbB-2, and estrogen receptor. In almost all breast cancer samples, the cancer cells demonstrated strong expression of cathepsin D in the cytoplasm, but weak staining patterns with other antibodies. Gastric and lung cancer cells did not respond with cathepsin D (except one metastatic lung cancer) or the other immunohistological markers. Since cathepsin D is strongly expressed in primary and metastatic lesions of breast cancer, cathepsin D could be useful as an adjunct to a panel of immunohistochemical stains in determining the primary site of origin of metastatic cancer in the skin.

Adenocarcinoma↗
PubMed1998

Purification and characterization of an NAD-malic enzyme from Bradyrhizobium japonicum A1017.

An NAD-malic enzyme was purified to homogeneity from Bradyrhizobium japonicum A1017, and its molecular characteristics were surveyed. The enzyme exhibited native and subunit molecular masses of 388 and 85 kDa, respectively, suggesting that it exists as a homotetramer, and was activated by metabolic intermediates in glycolysis. The role of the enzyme in bacteroids' carbon metabolism is discussed.

Amino Acid Sequence↗
PubMed1998

Complete bovine leukemia virus (BLV) provirus is conserved in BLV-infected cattle throughout the course of B-cell lymphosarcoma development.

Bovine leukemia virus (BLV) and human T-cell leukemia virus types 1 and 2 (HTLV-1 and HTLV-2) belong to the same subfamily of oncoviruses. Defective HTLV-1 proviral genomes have been found in more than half of all patients with adult T-cell leukemia examined. We have characterized the genomic structure of integrated BLV proviruses in peripheral blood lymphocytes and tumor tissue taken from animals with lymphomas at various stages. Genomic Southern hybridization with SacI, which generates two major fragments of BLV proviral DNA, yielded only bands that corresponded to a full-size provirus in all of 23 cattle at the lymphoma stage and in 7 BLV-infected but healthy cattle. Long PCR with primers located in long terminal repeats clearly demonstrated that almost the complete provirus was retained in all of 27 cattle with lymphomas and in 19 infected but healthy cattle. However, in addition to a PCR product that corresponded to a full-size provirus, a fragment shorter than that of the complete virus was produced in only one of the 27 animals with lymphomas. Moreover, when we performed conventional PCR with a variety of primers that spanned the entire BLV genome to detect even small defects, PCR products were produced that specifically covered the entire BLV genome in all of the 40 BLV-infected cattle tested. Therefore, it appears that at least one copy of the full-length BLV proviral genome was maintained in each animal throughout the course of the disease and, in addition, that either large or small deletions of proviral genomes may be very rare events in BLV-infected cattle.

Animals↗
PubMed1998

Differential regulation of MMP-2 and MMP-9 gelatinases in cultured human keratinocytes.

BACKGROUND: Among matrix metalloproteinases (MMPs), MMP-2 and MMP-9 are considered to play important roles in the tissue metabolism. OBJECTIVE: To study the production of MMP-2 and MMP-9 in cultured keratinocytes. METHODS: We examined the effect of cell passage number and cell differentiation on these enzymes by zymography and immunocytochemistry. RESULTS: Both MMP-2 and MMP-9 gelatinases were detected in keratinocyte-conditioned media using zymography. The level of MMP-2 in the medium decreased after sequential passage, whereas MMP-9 was detected at a constant level. Treatment of keratinocytes with Ca2+, a potent stimulator for cell differentiation. induced secretion of MMP-9, which was confirmed immunocytochemically. Inversely, treatment with retinoic acid, which inhibits cell differentiation, increased the level of MMP-2. CONCLUSION: These results suggest that keratinocytes regulate their secretion of MMP-2 and MMP-9 gelatinase in distinct and independent patterns during differentiation.

Calcium↗