Biomedical subjects

M Oka

Publications and source records attributed to M Oka.

At least 109 records · Page 6Linked to original sources

PubMed2000

Lymph node metastases identified with mediastinoscopy in a patient with superficial carcinoma of the esophagus.

Superficial esophageal cancers limited to the lamina propria are not associated with lymph node metastases. Mediastinoscopic transhiatal esophagectomy was planned in a patient with widespread superficial cancer of the midthoracic esophagus. Sampling of the upper mediastinal lymph nodes revealed metastases. The operation was converted to a transthoracic esophagectomy with radical lymphadenectomy. Histopathologic examination of the resection specimen showed three metastatic lymph nodes, despite local invasion limited to the lamina propria. This is the first report of a patient with superficial esophageal cancer and lymph node metastases.

Carcinoma, Squamous Cell↗

PubMed2000

Gains of 8q23-qter and 20q and loss of 11q22-qter in esophageal squamous cell carcinoma associated with lymph node metastasis.

BACKGROUND: Esophageal squamous cell carcinoma (ESCC) is associated with poor prognosis and lymph node metastasis is one of the critical prognostic factors. Although it is important to elucidate the genetic aberrations underlying its lymph node metastasis, to the authors' knowledge little is known regarding alterations in the primary ESCC that are linked with ESCC metastasis to the lymph nodes. METHODS: To elucidate genetic aberrations involved in the lymph node metastasis of ESCC, comparative genomic hybridization analysis was applied to 36 ESCC specimens, from 12 cases with no lymph node metastasis and 24 cases with lymph node metastasis. RESULTS: Copy number gains frequently were detected at 3q (75%), 8q23-qter (50%), 11q13 (44%), 5p14-pter (25%), 20q (25%), 7q (22%), 2p (19%), 12p (17%), and 20p (17%) and losses were detected at 18q (58%), 3p (50%), 9p (44%), 5q14-23 (39%), 4q (33%), 13q (22%), and 11q22-qter (19%). DNA amplifications were detected at four loci: 11q13, 2q12, 7q21, and 20q11.2 It is interesting to note that the gains of 8q23-qter (P < 0.0005) and 20q (P < 0.02) and loss of 11q22-qter (P < 0.05) were observed in tumors metastatic to the lymph nodes. The gains of 3q and 11q13 and losses of 18q, 3p, 9p, 5q14-23, and 4q were detected in both early and advanced stage ESCCs. CONCLUSIONS: These observations suggest that gains of 8q23-qter and 20q and loss of 11q22-qter allow the prediction of lymph node metastasis, and that gains of 3q and 11q13 and losses of 18q, 3p, 9p, 5q14-23, and 4q are associated with the development of ESCC.

Carcinoma, Squamous Cell↗

PubMed2000

Role of metabotropic glutamate receptor subclasses in modulation of adenylyl cyclase activity by a nootropic NS-105.

The involvement of metabotropic glutamate (mGlu) receptors in the modulatory actions of a novel cognition enhancer, (+)-5-oxo-D-prolinepiperidinamide monohydrate (NS-105), on adenylyl cyclase activity in rat cerebrocortical membranes and primary neuronal cultures was investigated using selective antagonists and antisense oligodeoxynucleotides for mGlu receptor subclasses. In rat cerebrocortical membranes, the inhibitory action of NS-105 (0.1 microM) on forskolin-stimulated cAMP formation was blocked by a group II mGlu receptor antagonist, (+/-)-alpha-ethylglutamic acid, and by a group III antagonist, (+)-2-amino-2-methyl-4-phosphonobutanoic acid (MAP-4), but not by a group I antagonist, (+/-)-1-aminoindan-1,5-dicarboxylic acid (AIDA), whereas the facilitation of cAMP formation by NS-105 (1 microM) in pertussis toxin-pretreated membranes was abolished by AIDA but not by (+/-)-alpha-ethylglutamic acid or MAP-4. In primary cultured neurons of mouse cerebral cortex, the inhibitory action of NS-105 on adenylyl cyclase activity disappeared after treatment with antisense oligodeoxynucleotides for group II (mGlu(2) and mGlu(3) receptors) and group III (mGlu(4) and mGlu(7) receptors) but not group I (mGlu(5) receptor) mGlu receptor subclasses. These findings suggest that the inhibitory action of NS-105 on adenylyl cyclase activity is mediated through group II and group III mGlu receptor subclasses while the facilitatory action is dependent on the group I mGlu receptor subclass.

Adenylyl Cyclases↗

PubMed2000

Inhibitory effect of Coptidis Rhizoma and berberine on the proliferation of human esophageal cancer cell lines.

Our previous study demonstrated that the herbal medicine, Oren-to, had antitumor effects on esophageal cancer cells (ECCs) in vitro. The purpose of this study was to examine which of the seven constituents of Oren-to had antitumor effects on esophageal cancer cells. MTT assay showed that, of the seven constituents, only the aqueous extract of Coptidis Rhizoma had potent inhibitory effect on the proliferation of two types of ECC lines, YES-3 and YES-4. In addition, the proliferation of all six types of ECC lines (YES-1 to YES-6) was inhibited in a dose-dependent manner (P<0.001 for all), when co-cultured at each concentration of Coptidis Rhizoma for 72 h. The ID50 of Coptidis Rhizoma for YES-1 to YES-6 was 2.2 microg/ml, 3.0 microg/ml, 0.25 microg/ml, 2.8 microg/ml, 2.5 microg/ml, and 0.5 microg/ml, respectively, berberine, one of protoberberine components of Coptidis Rhizoma, showed potent antitumor effects on all six types of ECC lines as well as Coptidis Rhizoma. In addition, the ID50 of berberine showed a positive correlation with that of Coptidis Rhizoma in six types of ECC lines examined (r2 = 0.763, P = 0.023). Cell cycle analysis of Coptidis Rhizoma-treated cancer cells showed the accumulation of cells in the G0/G1 phase and relative decrease of the S phase. These results support the possibility that the use of Coptidis Rhizoma containing abundant berberine may be useful as one of alternative therapies for esophageal cancers.

Antineoplastic Agents↗

PubMed2000

Evaluation of bioactive bone cement in canine total hip arthroplasty.

Total hip arthroplasties (THAs) were performed in beagle dogs using a bioactive bone cement (BABC) consisting of a silane-treated apatite- and wollastonite-containing glass-ceramic (AW glass-ceramic) powder and a silica glass powder as the filling particles and a bisphenol-A-glycidyl dimethacrylate-based resin (Bis-GMA-based resin) as the organic matrix. The outcomes were compared with the results of polymethylmethacrylate (PMMA) bone cement. The mechanical properties of the BABC were stronger than those of PMMA bone cement. The bonding strength of the BABC to bone in the dogs' femora increased with time and reached 3.7 MPa at 24 months after implantation whereas that of PMMA bone cement was 2.0 MPa (p < 0.05). Histological examination showed direct bonding between the BABC and the femoral bone for up to 24 months after implantation. However, with PMMA bone cement an intervening soft-tissue layer consistently was observed at the bone-cement interface. Direct bonding at the interface between the BABC and the bone through a calcium phosphorous layer 30 microm-thick was revealed by scanning electron microscopy. Femoral bone resorption was observed at 24 months after implantation in the BABC group, but it was not observed in the PMMA bone cement group. Direct bonding between BABC and the bone may have accelerated femoral bone resorption. Cement fractures of the BABC were observed on the acetabular side 24 months after implantation. Weak bonding between the BABC and an acetabular component made of ultrahigh molecular weight polyethylene (UHMWPE), relatively high elastic characteristics of BABC, and weakness of the calcium phosphorous layer formed on the surface of this cement seemed to lead to failure at 24 months on the acetabular side.

Animals↗

PubMed2000

Serial diffusion-weighted imaging in MELAS.

Clinical features of mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) resemble those of cerebral infarcts, but the pathogenesis of infarct-like lesions is not fully understood. To characterise these infarct-like lesions, we studied two patients with MELAS using diffusion-weighted (DWI) MRI before and after stroke-like episodes and measured the apparent diffusion coefficient (ADC) in the new infarct-like lesions. These gave high signal on DWI and had much higher ADC than normal-appearing regions. The ADC remained high even 30 days after a stroke-like episode then decreased in lesions, with or without abnormality as shown by conventional MRI. We speculate that early elevation of ADC in the acute or subacute phase reflects vasogenic rather than cytotoxic edema. The ADC of the lesions, which disappeared almost completely with clinical improvement, returned to normal levels, which may reflect tissue recovery without severe damage. To our knowledge, this is the first study of DWI in MELAS.

Adult↗

PubMed2000

Apparent diffusion coefficient measurements in progressive supranuclear palsy.

We measured the apparent diffusion coefficient (ADC), using diffusion-weighted imaging (DWI) and signal intensity on T2-weighted MRI in the cerebral white matter of patients with progressive supranuclear palsy (PSP) and age-matched normal subjects. In PSP, ADC in the prefrontal and precentral white matter was significantly higher than in controls. There was no significant difference in signal intensity on T2-weighted images. The ADC did correlate with signal intensity. The distribution of the elevation of ADC may be the consequence of underlying pathological changes, such as neurofibrillary tangles or glial fibrillary tangles in the cortex. Our findings suggest that ADC measurement might be useful for demonstrating subtle neuropathological changes.

Aged↗

PubMed2000

Autoimmune reactivity of sera to hepatocyte plasma membrane in type 1 autoimmune hepatitis.

Type 1 autoimmune hepatitis (AIH-1) is an organ-specific autoimmune liver disease for which no tissue-specific autoantigen has yet been identified. We examined the reactivity by sensitive immunoblotting with enhanced chemiluminescence (IB-ECL) of 43 sera from patients with AIH-1 and 182 sera from patients with other diseases on hepatocyte plasma membrane derived from rat or human liver (RHPM, HHPM) and separated by aqueous two-phase partition. The sera studied were from patients with AIH-1, primary biliary cirrhosis, chronic viral hepatitis, and systemic lupus erythematosus (SLE); and from normal subjects. Specificity of reactivity by IB-ECL was sought: (i) by testing sera on human or rat liver membrane; (ii) by testing sera on liver or kidney membrane; (iii) by serial titration of reactive sera; and (iv) by testing reactive sera from AIH-1 before and after successful treatment with prednisolone. The results were that in AIH-1 there were multiple reactive components which were not species-specific, since they were detected with both RHPM and HHPM, but were mostly tissue-specific for liver. There was no significant correlation between antinuclear antibodies (ANA) titer and the frequencies of sera reactivities against RHPM. Most of these reactive components were demonstrable at a lesser frequency in other liver diseases and in SLE. There was a striking decrease in reactivity by IB-ECL of AIH-1 sera with liver membrane after clinical remission, further suggesting that differences between AIH-1 and other inflammatory liver diseases and SLE are predominantly quantitative rather than qualitative. However, our study did point to candidate liver membrane antigens with molecular sizes of 136, 116, 81, and 49 kDa, additional to components previously described by others. The molecular identification of these prominent reactants with AIH-1 sera could prove informative for ascertaining pathogenesis.

Adult↗

PubMed2000

Production of nitric oxide from endothelial cells by 31-amino-acid-length endothelin-1, a novel vasoconstrictive product by human chymase.

Human chymase selectively converts big endothelin (ET)-1 to 31-amino-acid-length ET-1 [ET-1(1-31)]. In this study we examined effect of ET-1(1-31) on endothelial function. ET-1(1-31) evoked contraction in a concentration-dependent manner at > 10(-8) M, which was about 10 times weaker than that of conventional ET-1 [ET-1(1-21)]. BQ485, an ETA receptor antagonist, completely abolished ET-1(1-31)-induced contraction, but BQ788, an ETB receptor antagonist, slightly enhanced it, suggesting that ET-1(1-31) relaxes artery via endothelium. On endothelial cells, ET-1(1-21) and ET-1(1-31) increased [Ca2+]i and produced NO, both of which were significantly inhibited by BQ788 and not by BQ485. These results indicate that ET-1(1-31) increased [Ca2+]i and produced NO in endothelial cells through ETB receptor similarly with ET-1(1-21), although slight difference in effect on smooth muscle cells.

Animals↗

PubMed2000

Cytogenetic analysis of esophageal squamous cell carcinoma cell lines by comparative genomic hybridization: relationship of cytogenetic aberrations to in vitro cell growth.

Cancer is characterized by autonomous growth of cells, and it is widely accepted that cell proliferation is primarily influenced by individual cell genetics. To elucidate the mechanisms of cancer cell proliferation, we studied differences in genetic aberrations for different type of tumors with different proliferation characteristics. We employed comparative genomic hybridization (CGH) to detect genetic aberrations in six cell lines of esophageal squamous cell carcinoma (ESCC). Three cell lines (YES-1, -2, and -3) grow in culture without fetal calf serum (group A), while others require serum to be maintained in vitro (group B). Both groups showed very similar cytogenetic aberrations: over-representations of 11q13 (6/6), 8q23-qter (5/6), Xq25-qter (5/6), 3q26-qter (4/6), 5p (4/6), 7p15-pter (4/6), 8q21.3-q22 (4/6), 17p (4/6), and 20q13 (4/6), and under-representations of 18q21-qter (6/6), 4q28-q33 (4/6), and 9p21 (4/6). Six amplification loci were mapped to chromosomal regions of 6q23 (1 case), 7p12 (2 cases), 9p21 (1 case), 11p11.2-12 (3 cases), 11q13 (2 cases), and 17p12 (2 cases). However, some differences were detected. DNA copy number increases at 7p12-p13, 11q14-q22, and 11q22-qter and under-representations of 4p, 8p, and 11p14-pter. In contrast, gains at 12p and 20p, and losses at 3p and 5q were detected only in group-B cell lines. These observations suggest that cytogenetic differences between the two groups may be linked to differences in cell growth characteristics in vitro, and that the genes in these chromosomal regions may play important roles in cell proliferation.

Carcinoma, Squamous Cell↗

PubMed2000

Altered biochemical markers of bone turnover in humans during 120 days of bed rest.

Microgravity induces significant and progressive bone loss in both humans and animals. This is the consequence of disturbed bone remodeling. We performed a bed rest experiment to simulate microgravity and tried to clarify bone metabolism by measuring biochemical markers of bone turnover. Six healthy volunteers participated in 120 days of bed rest. The parameters of calcium homeostasis, calcitropic hormones, and biochemical markers of bone turnover were examined. After ambulatory control evaluation, all subjects underwent 120 days of bed rest. Metabolic evaluation was performed in a baseline period, and on days 7, 16, 50, 72, 92, and 108 during bed rest, and on days 10 and 25 during a recovery period. Bed rest induced an increase in urinary calcium (Ca) excretion and serum Ca and bone resorption markers. Urine pyridinoline, deoxypyridinoline, and type I collagen cross-linked N-telopeptide increased more rapidly than urinary Ca excretion and serum Ca. Tartrate-resistant acid phosphatase (TRAP) increased even in the recovery period. Carboxy-terminal propeptide of type I collagen, a bone formation marker, significantly decreased on days 50, 92, and 108 of bed rest. These changes of biochemical markers of bone metabolism, except for TRAP, rapidly returned toward control levels in the recovery period. Immunoreactive parathyroid hormone showed a modest decrease during bed rest and a significant increase in the recovery period. Insulin-like growth factor I (IGF-I) and its binding protein, insulin-like growth factor binding protein-3, increased during bed rest, indicating the possibility of resistance to IGF-I in bones under reduced mechanical stress and strain. Bone loss from unloading results from the combination of acceleration of bone resorption and subsequent retardation of bone formation.

Adult↗

PubMed2000

An antisense strategy for inhibition of human melanoma growth targets the growth factor pleiotrophin.

A major biological characteristic of metastatic melanomas is their ability to survive in a growth-factor-depleted environment, whereas normal melanocytes die rapidly under such conditions. The increased survival of melanoma cells is due to their production of growth factors for autocrine growth stimulation. Here, we describe a strategy to inhibit pleiotrophin (PTN), a heparin-binding autocrine growth factor for melanoma cells. To target PTN production in melanoma cells, a replication-deficient, recombinant adenovirus was generated to express antisense (AS) PTN at high efficiency. The AS vector induced transcripts that completely inhibited PTN protein production. Melanoma growth was strongly inhibited if the tumor cells were maintained in a three-dimensional environment in soft agar, whereas cell growth was not affected if the tumor cells were grown as a monolayer, suggesting the importance of cell-matrix interactions for the biological activity of this growth factor. The down-regulation of PTN in transduced melanoma cells coincided with the down-regulation of the cell-cycle regulator cyclin E and the up-regulation of the cell-cycle inhibitor p21WAF1/Cip1. Tumor growth in vivo was also delayed by the AS-PTN vector, confirming that PTN is essential for the three-dimensional growth of tumor cells. Our studies demonstrate the importance of assessing potential melanoma antagonists not only on cells grown as monolayers but also in three-dimensional matrices.

Adenoviridae↗

PubMed2000

Small Gtpase rab3A is associated with melanosomes in melanoma cells.

Rab3A is a small guanosine triphosphate (GTP)-binding protein that has been recently implicated in intracellular vesicle transport and the secretion of neurotransmitters in neuronal cells. We demonstrate here that Rab3A is associated with melanosomes in pigment cells. Rab3A as well as Rabphilin3A, a putative target protein of Rab3A, were detected in the melanosome fraction, purified from B16 murine melanoma cells by sucrose density gradient ultracentrifugation. In contrast, Rab GDP dissociation inhibitor (GDI), a GDP/GTP exchange protein for Rab3A, was found in the cytosol fraction. Further studies using confocal laser scanning microscopy and immunoelectron microscopy revealed that immunoreactive Rab3A is localized in conjunction with the melanosomal membrane. These results suggest the possibility of involvement of Rab3A-Rabphilin3A complex, regulated by Rab GDI, in the intracellular transport of melanosomes in pigment cells.

Adaptor Proteins, Signal Transducing↗

PubMed2000

Interleukin-8 overexpression is present in pyoderma gangrenosum ulcers and leads to ulcer formation in human skin xenografts.

Interleukin-8 (IL-8) is a potent chemotactic polypeptide for neutrophils. However, the role of this cytokine during inflammation remains unclear. Skin specimens from patients with pyoderma gangrenosum demonstrated IL-8 overexpression in skin ulcers, which suggests a role for IL-8 in the development of the disease. We therefore constructed a recombinant adenovirus expressing the complementary deoxyribonucleic acid encoding human IL-8 (IL-8/Ad5) that induces a 2000-fold increase in IL-8 expression of infected human fibroblasts in vitro. Human skin engrafted to severe combined immunodeficiency mice and then injected with the recombinant virus demonstrated erythema, an intense perivascular infiltration of neutrophils, and extravasation of erythrocytes after 8 hours. By 12 hours after injection, neutrophils had accumulated beneath the epidermis, which then necrotized, and one or more ulcers that remained for approximately 2 weeks were observed. Clinically and histologically, the ulcers resembled pyoderma gangrenosum. These clinical and experimental findings suggest an etiologic role of IL-8 in the pathogenesis of pyoderma gangrenosum.

Animals↗

PubMed2000

Effects of (+)-pentazocine and 1,3-di-o-tolylguanidine (DTG), sigma (sigma) ligands, on micturition in anaesthetized rats.

The effects of two sigma (sigma) binding site ligands, (+)-pentazocine and 1,3-di-o-tolylguanidine (DTG), on bladder functions were examined in rats. Cystometry using urethane-anaesthetized rats showed that (+)-pentazocine (1 - 5 mg kg(-1), i.v.) and DTG (1 - 5 mg kg(-1), i.v.) prolonged micturition intervals, indicating increased bladder capacity and raised the threshold pressure. The effects of (+)-pentazocine (2 mg kg(-1), i.v. ) on micturition were not influenced by naloxone (0.5 mg kg(-1), i.v. ), which antagonized similar effects of morphine (2 mg kg(-1), i.v.). When administered intracerebroventricularly (i.c.v.), DTG (1 microg) and (+)-pentazocine (30 microg) prolonged micturition intervals with increased threshold pressure on the cystometrogram. In isolated bladder detrusor strips of rats, (+)-pentazocine (3 microM) and DTG (1 microM) did not affect contractile responses to electrical field stimulation. A higher concentration of DTG (3 microM) slightly suppressed the response induced by 30 Hz stimulation. The effects of (+)-pentazocine and DTG on micturition were abolished by pre-treatment with pertussis toxin (PTX, 1 microg, i.c.v.). These results indicate that typical sigma ligands, such as (+)-pentazocine and DTG, increase bladder capacity in anaesthetized rats. Moreover, the mechanism by which sigma ligands change the urinary storage properties in rats may involve pathways in which the function of Gi/o proteins is necessary.

Anesthesia↗

PubMed2000

Regulation of melanogenesis through phosphatidylinositol 3-kinase-Akt pathway in human G361 melanoma cells.

The involvement of the phosphatidylinositol 3-kinase pathway in the regulation of melanogenesis was examined using human G361 melanoma cells. In the cells treated with wortmannin, a potent inhibitor of phosphatidylinositol 3-kinase, the melanin content increased concomitant with the elevated protein level of tyrosinase, a key enzyme in melanogenesis. Northern blot analysis revealed that the mRNA level of tyrosinase increased transiently on treatment of the cells with the phosphatidylinositol 3-kinase inhibitor. When the cells were infected with the adenovirus vector encoding the mutant adapter subunit of phosphatidylinositol 3-kinase, which acts as a dominant negative of phosphatidylinositol 3-kinase, both the melanin content and the expression of tyrosinase increased. In cells infected with the adenovirus vector encoding the constitutively active mutant of the lipid kinase, a decrease in melanin content as well as reduced expression of tyrosinase was observed. In cells expressing the constitutively active mutant of the serine-threonine protein kinase Akt, one of the downstream targets of phosphatidylinositol 3-kinase, the melanin content decreased as in the cells overproducing the constitutively active mutant of phosphatidylinositol 3-kinase. These results indicate that phosphatidylinositol 3-kinase regulates melanogenesis by modulating the expression of tyrosinase, and that activation of Akt is sufficient for suppression of melanin production in G361 melanoma cells.

Androstadienes↗

PubMed2000

Elimination of CD4(+) T cells enhances anti-tumor effect of locally secreted interleukin-12 on B16 mouse melanoma and induces vitiligo-like coat color alteration.

CD4(+) T cells have been reported to suppress immunity against cancer in certain animal models. In this study, we investigated the role of CD4(+) T cells in the anti-tumor immune response when interleukin-12-producing melanoma cells are inoculated in mice. We found that interleukin-12-transfected B16 melanoma showed retarded tumor growth in syngeneic mice; however, all the mice developed tumors eventually. In vivo depletion of CD4(+) T cells led to complete regression of B16/interleukin-12 tumors in 12 of 20 mice (60%). Immunohistochemical analyses revealed that a number of CD8(+) T cells accumulated in close proximity to the B16/interleukin-12 tumors in the CD4(+) T cell-depleted mice, whereas CD8(+) T cells were only scarcely observed at the periphery of the tumors in control immunocompetent mice. Furthermore, 10 of 20 mice treated with both B16/interleukin-12 inoculation and CD4(+) T cell depletion exhibited vitiligo-like coat color alteration. B16/interleukin-12 tumors completely regressed in all the mice with vitiligo. Histologic examination showed that CD8(+) lymphocytes accumulated around the hair bulbs of mice with vitiligo, but not in those without vitiligo. These results suggest that CD4(+) T cells have an inhibitory effect on tumor rejection by suppressing cytotoxic CD8(+) T cells in this melanoma loading model with local interleukin-12 secretion. To investigate the mechanism of enhanced anti-tumor effects by CD4(+) T cell depletion, we examined the T helper type 1/2 cytokine profile in the tumor draining lymph nodes of B16/interleukin-12-bearing mice with or without CD4(+) T cell depletion using the reverse transcription-polymerase chain reaction method. We found that CD4(+) T cell depletion eliminated T helper type 2 cells and resulted in a T helper type 1-dominant cytokine profile in tumor draining lymph nodes. We emphasize that this T helper type 1-dominant cytokine profile may generate further activated CD8(+) T cells against B16 melanoma cells, lead B16/interleukin-12 to regress, and result in the destruction of the melanocytes in hair bulbs due to cross-antigenicity between both cell types. This mouse model not only demonstrates the depletion of CD4(+) T cells as a useful strategy for cancer gene therapy with interleukin-12 but also provides a model for human melanoma-associated vitiligo.J Invest Dermatol 115:1059-1064 2000

Animals↗

PubMed2000

High incidence of SV40-like sequences detection in tumour and peripheral blood cells of Japanese osteosarcoma patients.

Recent studies have revealed the evidence for the significance of SV40 genome in human malignancies. In this paper, the presence of SV40-like sequences was investigated in 54 Japanese osteosarcomas in which mutations of the retinoblastoma (Rb), p53, MDM2, and CDK4 genes had been already analysed. Using polymerase chain reaction and Southern hybridization, SV40-like sequences were detected in 25 cases (46.3%). In most cases, only a part of SV40 genome was detected, and the regulatory region containing enhancer sequences was most frequently found (21/54, 38.9%). There was no apparent relationship between the presence of SV40-like sequences and tumour suppressor genes mutations in each tumour. The SV40-like sequences were also detected in peripheral blood cells of substantial proportion of the patients (43.3%), whereas the incidence was much lower (4.7%) in normal healthy controls. This difference is statistically highly significant (P < 0.0001), suggesting that the presence of SV40-like sequences, even if only a part, may play some roles to predispose individuals to osteosarcoma.

Adolescent↗