Biomedical subjects

T Sasaki

Publications and source records attributed to T Sasaki.

At least 109 records · Page 6Linked to original sources

PubMed2003

S 12911-2 inhibits osteoclastic bone resorption in vitro.

The potential anti-osteoporotic activity of the strontium compound, S12911, was tested on osteoclast-like cells and on cultured fetal mouse long bones. From 1 mM Sr2+, S12911 reduced both basal and stimulated bone resorption by decreasing osteoclast activity and ruffled border formation. The aim of this study was to evaluate the effects of S 12911-2 on osteoclastic bone resorption using in vitro systems. Osteoclast-like cells, produced in vitro by co-culture of mouse bone marrow cells with primary osteoblasts, were allowed to settle on dentine slices, and the area of resorption pits formed after 48 h was measured using an image analysis system. S 12911-2, at a minimal active concentration of 1 mM Sr2+, significantly reduced pit formation by these cells (p < 0.05). Pretreatment of slices for 48 h with S 12911-2 (5 mM Sr2+) did not produce appreciable inhibition of resorption. Bone resorption in cultured fetal mouse long bones was assessed by measuring the release of pre-incorporated 45calcium. S 12911-2 inhibited resorption in control cultures (18.9%, p < or = 0.05) and in bones cultured with the active form of vitamin D3 [1,25(OH)2D3] (44.5%, p < or = 0.05). S 12911-2 had no effect on the number of osteoclasts observed histochemically in longitudinal sections prepared from fetal mouse long bones. Electron microscopy of mouse long bones treated with S 12911-2 (3 mM Sr2+) showed osteoclasts with clear zones facing the bone surface, but without well-developed ruffled borders; untreated bones contained osteoclasts with normal ruffled borders. These results indicate that S 12911-2 inhibits osteoclast activity. This effect is directly linked to the presence of strontium, is effective on basal and stimulated resorption, and involves a decrease in ruffled border formation by osteoclasts.

Animals↗

PubMed2003

[Left ventricular papillary fibroelastoma associated with chief complaints of palpitation, general fatigue, and feverish].

Papillary fibroelastoma is one of the commonest benign tumor in the heart. In almost all of cases, symptoms never develop and the tumors are usually discovered coincidentally. Even though papillary fibroelastoma is a benign tumor, surgical extirpation is usually indicated for reason of productive serious complications. The tumors may cause left ventricular outflow obstruction, cerebral embolic infarction, myocardial infarction and even sudden death. The case we reported here is unusual case, because the patient developed symptoms and complaints such as palpitation, feverish and general fatigue. We measured tumor markers, interleukin 6, serotonin and histamine, but none of those was elevated in the blood samples. Surgical removal of the tumor attached to the base of posterior papillary muscle was carried out without causing mitral incompetence, and the pathological findings were compatible with papillary fibroelastoma. After the operation, the both symptoms and complaints disappeared unexpectedly.

Fatigue↗

PubMed2002

Inhibition of proliferation and induction of differentiation of glioma cells with Datura stramonium agglutinin.

We found that a lectin, Datura stramonium agglutinin, induced irreversible differentiation in C6 glioma cells. The differentiated cells had long processes, a low rate of proliferation and a high content of glial fibrillary acidic protein. When the medium was replaced with Datura stramonium agglutinin-free medium after 1 h, cell proliferation continued to be inhibited. Experiments with several other lectins indicated that both recognition of linear N-acetyllactosamine repeats and recognition of multiantennary units of cell-surface glycans were required for the inhibition of C6 proliferation. Proliferation of four human glial tumour cells was also inhibited by Datura stramonium agglutinin. Further, these differentiated human glial tumour cells had long processes and a high content of glial fibrillary acidic protein similar to differentiated C6 glioma cells. Taken together, these observations suggest that Datura stramonium agglutinin may be useful as a new therapy for treating glioma without side effects.

Agglutinins↗

PubMed2002

Coherence incoherence and dimensional crossover in layered strongly correlated metals.

The properties of an interacting electron system depend on the electron correlations and the effective dimensionality. For example, Coulomb repulsion between electrons may inhibit, or completely block, conduction by intersite electron hopping, thereby determining whether a material is a metal or an insulator. Furthermore, correlation effects increase as the number of effective dimensions decreases; in three-dimensional systems, the low-energy electronic states behave as quasiparticles, whereas in one-dimensional systems, even weak interactions break the quasiparticles into collective excitations. Dimensionality is particularly important for exotic low-dimensional materials where one- or two-dimensional building blocks are loosely connected into a three-dimensional whole. Here we examine two such layered metallic systems with angle-resolved photoemission spectroscopy and electronic transport measurements, and we find a crossover in the number of effective dimensions from two to three with decreasing temperature. This is apparent from the observation that, in the direction perpendicular to the layers, the materials have an insulating character at high temperatures but become metal-like at low temperatures, whereas transport within the layers remains metallic over the whole temperature range. We propose that this change in effective dimensionality correlates with the presence of coherent quasiparticles within the layers.

Journal Article↗

PubMed2002

Prenatal ultrasonographic appearance of type IIId (uncorrectable type with cystic dilatation) biliary atresia.

Although prenatal ultrasonographic (US) diagnosis has been reported in biliary atresia (BA), most cases are type I (correctable with cystic dilatation). We report three prenatal cases of type IIId BA (uncorrectable with cystic dilatation). Routine fetal US at 22 to 24 weeks of gestation showed two communicating cystic lesions 12 to 16 mm in diameter. On color Doppler US, the lesions were separate from the portal vein or hepatic artery. The size did not change during the prenatal period in any case. Choledochal cyst (CC) was considered the most likely diagnosis, although BA with cystic lesions was also considered. After birth, the patients developed acholic stools and prolonged neonatal jaundice. Hepatobiliary scintigraphy showed negative passage. Duodenal fluid showed a negative or slightly positive Gmelin test. The neonates underwent laparotomy at the age of 36, 46, and 32 days, respectively. Intraoperative cholangiography showed the gallbladder and slightly-dilated common-bile duct without entering the proximal or distal bile ducts in all cases. They were classified as type IIId BA and underwent excision of the cystic lesions and dissection of the portal bile-duct remnants, followed by hepatic portoenterostomy. Case 1 showed persistent jaundice and finally underwent liver transplantation (LTx), case 2 became anicteric. Case 3 remained jaundiced and is to undergo LTx. In conclusion, type IIId BA may be one of the differential diagnoses when a cystic lesion is detected under the hepatic hilum by fetal US. However, prenatal diagnosis of BA is still difficult with respect to differentiation from a CC or type I BA. Early postnatal diagnosis followed by immediate treatment is important, especially in type IIId BA.

Bile Ducts↗

PubMed2002

Novel pathway to the growth of diamond on cubic beta-SiC(001).

By carrying out first-principles calculations on diamond-forming processes, we predict a method for the heteroepitaxial growth of diamond on cubic beta-SiC(001). In the method, we used two processes: (i) the preformation of an sp(3)-like surface configuration of beta-SiC(001) by the adsorption of group-V surfactants; (ii) the successive growth of diamond by the segregation of the surfactants onto a surface and the desorption of surface hydrogen. Analyzing the segregation energies, we found that the atomic size effect plays a crucial role in the surfactant-mediated growth of diamond on beta-SiC(001).

Journal Article↗

PubMed2002

Pressure-induced transition from a charge-disproportionated antiferromagnetic state to a charge-uniform ferromagnetic state in Sr(2/3)La(1/3)FeO3.

The perovskite oxide Sr(2/3)La(1/3)FeO3 has been found to switch its electronic ground state drastically at 23 GPa through measurements of 57Fe Mössbauer spectroscopy and powder x-ray diffraction up to 56 GPa. In the low-pressure region a first-order transition from a charge-uniform paramagnetic metallic phase to a charge-disproportionated (3Fe(11/3+)-->2Fe(3+)+Fe5+) antiferromagnetic insulating phase occurs at 207 K at 0.1 MPa and 165 K at 21 GPa, typically. Above 25 GPa, however, a charge-uniform ferromagnetic (and most probably metallic) phase persists below 300 K. This switching occurs at a lattice volume of V(23 GPa)/V(0)(0.1 MPa) = 0.89.

Journal Article↗

PubMed2002

Measurement of serum total bile acid levels in long-term postoperative follow-up of patients with congenital bile-duct dilatation.

Serum total bile acid levels (STBA), a sensitive indicator of cholestasis, were measured during the long-term postoperative period in patients with congenital bile-duct dilatation (CBDD) (choledochal cyst) and the factors contributing to elevation of STBA were analyzed in 44 patients. Their ages at operation ranged from 1 month to 16 years. A STBA level over 12 nmol/ml on two or more measurements during outpatient follow-up was considered abnormal. Patients were classified into three groups: group 1, STBA, 12-50 nmol/ml; group 2, STBA > or = 50 nmol/ml; group N, STBA normal. In 19 patients (43.2%) STBA was normal. Of the 25 patients (56.8%) with elevated STBA, groups 1 and 2 comprised 12 (27.3%) and 13 patients (29.5%), respectively. The mean age in group N was 5.1 +/- 4.2 years, which was higher than in groups 1 (2.6 +/- 2.3) and 2 (2.3 +/- 2.5 years) ( P< 0.05). Preoperative STBA and total bilirubin were higher in group 2 (79.2 +/- 75.1 nmol/ml resp. 5.2 +/- 4.2 mg/dl) than in groups N (20.1 +/- 32.6, 1.3 +/- 1.4) and 1 (22.8 +/- 37.2, 1.4 +/- 1.0) ( P< 0.05). Preoperative alkaline phosphatase and gamma-glutamyl transpeptidase were higher in group 2 (1,006 +/- 872 IU/l, 452 +/- 326 IU/l) than in group N (573 +/- 371, 205 +/- 238) ( P< 0.05). Histologic findings on liver biopsy showed fibrosis in 38.5% of group 2 patients, which was significantly higher than in groups N (15.8%) and 1 (16.7%) ( P< 0.05). Cholestasis was detected in 41.7% of group 1 and 61.5% of group 2 patients, compared to 10.5% of group N patients ( P< 0.05). Postoperative elevation of STBA may thus persist in more than one-half of patients with CBDD, and is likely to occur in patients of young age who have severe cholestasis or liver fibrosis preoperatively. Further investigations may be required in regard to the development of postoperative complications.

Adolescent↗

PubMed2002

Contractile responses to reactive oxygen species in the canine basilar artery in vitro: selective inhibitory effect of MCI-186, a new hydroxyl radical scavenger.

BACKGROUND: Cerebral vasospasm is one of the important pathological phenomena which influence morbidity and mortality following subarachnoid haemorrhage. Reactive oxygen species (ROSs) generated by the autoxidation of oxyhemoglobin to methemoglobin may be one of the essential factors in the pathogenesis of cerebral vasospasm. The direct vasocontractile effects of hydrogen peroxide (H(2)O(2)), superoxide anion (O(2)(-)), and hydroxyl radical (*OH) on the canine basilar artery and the inhibitory effects of MCI-186 (3-methyl-1-phenyl-2-pyrazolin-5-one), a new *OH scavenger, were investigated. METHOD: Isometric tension was recorded in basilar artery rings from dogs in vitro. H(2)O(2), pyrogallol (O(2)(-) donor), and vitamin C (VitC)/Fe(2+) (*OH-generating system) were used to generate the ROSs. FINDINGS: H(2)O(2) (10 micromol/L), pyrogallol (10 micromol/L), and VitC/Fe(2+) (100 micromol/L each) induced fast onset and transient, slow onset and transient, and sustained contraction, respectively, in the canine basilar artery. Contractions induced by H(2)O(2) were almost completely inhibited by pre-incubation with catalase (800 U/mL) and those by pyrogallol with superoxide dismutase (150 U/mL), but neither with MCI-186 (10 micromol/L). The contraction induced by VitC/Fe(2+) was clearly inhibited by pre-incubation with MCI-186, but not with catalase or superoxide dismutase. INTERPRETATION: ROSs have direct vasocontractile effects on the canine basilar artery in vitro, but different ROSs have different contractile characteristics. Such contractions might be related to the pathophysiology of cerebral vasospasm. MCI-186 had a clear and selective inhibitory effect against *OH-induced contraction in vitro. Comparison of different radical scavengers may be important in pharmacological assessment, especially targeted on cerebral vasospasm.

Animals↗

PubMed2002

Calcified vestibular schwannoma with unusual histological characteristics - positive immunoreactivity for CD-34 antigen.

Calcification in vestibular schwannoma is extremely rare. A 36-year-old man presented with a history of decreased hearing on the left since childhood. Computed tomography showed a left cerebellopontine angle lesion protruding into the porus acousticus and enlarging the internal auditory meatus, with significant deposits of calcification. Histological and immunohistochemical examination, including staining for CD-34, a myeloid progenitor cell antigen, found highly degenerated schwannoma with collagen-rich tissue, calcification, formation of bone, abnormal vessels of various sizes, and old haemorrhage with marked haemosiderin-laden macrophages. Most of the surgical specimen was sclerotic collagenous tissue containing sparse spindle-shaped cells which formed approximately 90% of the total specimen. However, the spindle-shaped cells were partly concentrated into islands forming the cellular part (approximately 10% of the total). The spindle-shaped cells in both parts showed almost typical immunohistochemical characteristics of schwannoma. However, many spindle-shaped cells in only the sclerotic part were positive for CD-34, which is widely used for the diagnosis of solitary fibrous tumours. Cerebellopontine angle tumour showing fibromatous tissue, including calcification, may contain foci of typical schwannoma. Careful histological examination with detailed immunohistochemical staining is required for the correct diagnosis. In particular, spindle-shaped cells occasionally show positive immunoreactivity for CD-34 antigen in the areas of degenerated and calcified schwannoma characteristic of our case.

Adult↗

PubMed2002

Expression of metastasis suppressor gene (KAI1/CD82) in oral squamous cell carcinoma and its clinico-pathological significance.

In this study, we investigated the expression of the KAI1/CD82 gene in oral squamous cell carcinoma (oral SCC). We studied 43 oral SCC patients. Reverse transcription-polymerase chain reaction (RT-PCR) analysis was performed to evaluate expression of this gene, and results were compared to the clinico-pathological findings. Twenty-five specimens (58.1%) were KAI1/CD82-positive, and 18 (41.9%) were negative. There were statistically significant relationships between gene expression and both histological malignancy (P=0.0205) and mode of invasion (P=0.0315). But there were no correlations of expression with tumor status, regional lymph node metastasis, pathological lymph node metastasis or histological differentiation. No significant relationship was observed between patient survival and expression of KAI1/CD82 by tumors. The results of this study suggest that the KAI1/CD82 gene may not be a useful predictor of prognosis, although decreased gene expression may be associated with increased invasive ability of oral SCC.

Adult↗

PubMed2002

MR imaging of benign and malignant lesions in the buccal space.

OBJECTIVES: To evaluate MRI characteristics of buccal space lesions and to discuss the sensitivity of MRI in predicting malignancy of those lesions. METHODS: Thirty patients with malignant (n=7) or benign (n=23) lesions originating in the buccal space were reviewed retrospectively. MR images were assessed for the margins, internal architecture, signal intensity of lesions and their relation to the surrounding structures. RESULTS: Two cases of soft tissue sarcoma were shown as ill-defined masses with infiltration into adjacent muscles and bone. On the other hand, all tumors of minor salivary gland origin, whether malignant (n=4) or benign (n=2), were well-defined and confined within the buccal fat pad without infiltration into surrounding structures. All haemangiomas (n=9) had very high T2-weighted signal intensity. Three out of them contained signal voids on all sequences thought to represent phleboliths, a finding strongly suggestive of the diagnosis. Inflammatory lesions were characterized by the presence of edema in the surrounding fat. When ill-defined margins, infiltration into muscles and bone destruction were used as the criteria for the malignancy, only two out of seven malignant tumors were correctly diagnosed (sensitivity 29%). CONCLUSIONS: Although MR imaging was useful in demonstrating the extent of buccal space lesions, its diagnostic value in predicting malignancy was very limited. It was especially true for malignant tumors of minor salivary gland origin, which were typically seen as well-defined masses without infiltration into surrounding structures on MRI.

Adipose Tissue↗

PubMed2002

Osteoid osteoma in the mandible.

A case of osteoid osteoma (OO) in the mandible of 26-year-old female is presented. Her main complaint was intermittent pain during a 3 year period. The panoramic radiograph of the mandible showed diffuse sclerosis including an ill-defined circular radiopacity in the molar region. Computed tomography (CT) revealed an osseous lesion of 10 mm diameter that was located in the cortical bone of the mandible. Bone scintigraphy showed a localized region of high uptake of 99mTc HMDP. The lesion was diagnosed as an OO by histopathological examination of the surgical specimen and CT findings. Since radiological appearance has very significant meaning in the differentiation of an OO from other bone forming tumors, CT is the method of choice when the main symptom is pain and the conventional radiography was not informative.

Adult↗

PubMed2002

Mandibular bone invasion by gingival carcinoma on dental CT images as an indicator of cervical lymph node metastasis.

OBJECTIVES: To evaluate the significance of mandibular bone invasion by gingival carcinoma revealed by reformatted dental CT images as a prognostic indicator of cervical metastasis. METHODS: Thirty-two patients with squamous cell carcinoma of the lower gingiva were examined by dental CT. Cervical metastases and survival rates of these patients were analysed in relation to their clinical characteristics, histologic grading based on gingival biopsy, and mandibular bone invasion using reformatted dental CT imaging diagnoses prior to surgery. The dental CT images were classified into four types: Class I, no bone invasion; Class II, invasion confined to the alveolus; Class III, invasion extending between the alveolus and the mandibular canal; and Class IV, invasion beyond the mandibular canal. RESULTS: Logistic multivariate regression analysis showed that bony invasion identified on dental CT images was a significant prognostic factor in cervical metastases (P=0.028). The 5-year overall survival rates of Classes I, II, III, and IV were 100% (n=9), 76.2% (n=9), 71.4% (n=7), and 28.6% (n=7), respectively. CONCLUSIONS: The evaluation of mandibular bone invasion using dental CT images is useful as a prognostic indicator of cervical metastasis for patients with gingival carcinoma.

Adult↗

PubMed2002

Potential role of phosphodiesterase 7 in human T cell function: comparative effects of two phosphodiesterase inhibitors.

Even though the existence of phosphodiesterase (PDE) 7 in T cells has been proved, the lack of a selective PDE7 inhibitor has confounded an accurate assessment of PDE7 function in such cells. In order to elucidate the role of PDE7 in human T cell function, the effects of two PDE inhibitors on PDE7A activity, cytokine synthesis, proliferation and CD25 expression of human peripheral blood mononuclear cells (PBMC) were determined. Recombinant human PDE7A was obtained and subjected to cyclic AMP-hydrolysis assay. PBMC of Dermatophagoides farinae mite extract (Df)-sensitive donors were stimulated with the relevant antigen or an anti-CD3 monoclonal antibody (MoAb). PBMC produced IL-5 and proliferated in response to stimulation with Df, while stimulation with anti-CD3 MoAb induced CD25 expression and messenger RNA (mRNA) synthesis of IL-2, IL-4 and IL-5 in peripheral T cells. A PDE inhibitor, T-2585, which suppressed PDE4 isoenzyme with high potency (IC50 = 0.00013 microM) and PDE7A with low potency (IC50 = 1.7 microM) inhibited cytokine synthesis, proliferation and CD25 expression in the dose range at which the drug suppressed PDE7A activity. A potent selective inhibitor of PDE4 (IC50 = 0.00031 microM), RP 73401, which did not effectively suppress PDE7A (IC50 > 10 microM), inhibited the Df- and anti-CD3 MoAb-stimulated responses only weakly, even at 10 microM. PDE7 may play a critical role in the regulation of human T cell function, and thereby selective PDE7 inhibitors have the potential to be used to treat immunological and inflammatory disorders.

3',5'-Cyclic-AMP Phosphodiesterases↗

PubMed2002

Bone induction in subcutaneous tissue in rats by a newly developed DNA-coated atelocollagen and bone morphogenetic protein.

A unique biomaterial, a mixture of DNA and collagen (DNA/collagen), was developed and its efficacy as a carrier matrix for bone morphogenetic protein (BMP) was evaluated histologically. The material was prepared as a composite of DNA from salmon milt and pepsin-digested type I collagen (atelocollagen) from bovine dermis. Phase-contrast and fluorescence microscopy showed atelocollagen fibres with DNA coating. The dose-response and time-course of bone induction by BMP in DNA/collagen (5 x 10 x 1 mm) in the subcutaneous tissue was investigated in 20 male Wistar rats. The BMP/DNA/collagen induced new bone in a dose-dependent manner (0, 25, 50 or 100 micrograms of BMP). Histological examination in the time-course study showed that the BMP (100 micrograms)/DNA/collagen induced bone formation, while the DNA/collagen alone resulted in the accumulation of fibroblasts. These results indicate that the DNA/collagen is effective as a carrier matrix for BMP. It provides a cell anchorage for differentiation of osteoblasts and is absorbed as bone matures.

Absorbable Implants↗

PubMed2002

3D culture of murine hematopoietic cells with spatial development of stromal cells in nonwoven fabrics.

BACKGROUND: The in vivo hematopoietic microenvironment is composed of stromal cells and extracellular matrix in a 3D configuration. We have created a 3D microenvironment in vitro, employing spatial development of stromal cells in a nonwoven fabric porous carrier, Fibra-cel (FC). We compared its performance with that of a 2D microenvironment. METHODS: Primary murine BM cells were inoculated on the layers of stromal cells prepared in FC (3D) or on a dish (2D) and cultured for 7-21 days. The hematopoietic cells harvested from the cultures were evaluated by colony-forming unit (CFU) assay and transplantation to sub lethally irradiated mice. RESULTS: The maximum stromal cell concentration in the 2D culture was higher than that in the 3D culture. However, the hematopoietic cell concentration in the 3D culture was kept at a higher level than that in the 2D culture. The number of CFU-mix increased five times during 3D cultivation, but decreased in the 2D culture. The engraftment percentage of 3D cultured cells was comparable with that of fresh cells, and markedly higher than that of 2D cultured cells. DISCUSSION: The 3D culture constructed with FC and stromal cells was clearly superior to 2D culture because hematopoietic progenitor cells were expanded without the addition of cytokines and the content of hematopoietic stem cells was maintained.

Animals↗

PubMed2002

Enhanced resistance to seed-transmitted bacterial diseases in transgenic rice plants overproducing an oat cell-wall-bound thionin.

Bacterial attack is a serious agricultural problem for growth of rice seedlings in the nursery and field. The thionins purified from seed and etiolated seedlings of barley are known to have antimicrobial activity against necrotrophic pathogens; however, we found that no endogenous rice thionin genes alone are enough for resistance to two major seed-transmitted phytopathogenic bacteria, Burkholderia plantarii and B. glumae, although rice thionin genes constitutively expressed in coleoptile, the target organ of the bacteria. Thus, we isolated thionin genes from oat, one of which was overexpressed in rice. When wild-type rice seed were germinated with these bacteria, all seedlings were wilted with severe blight. In the seedling infected with B. plantarii, bacterial staining was intensively marked around stomata and intercellular spaces. However, transgenic rice seedlings accumulating a high level of oat thionin in cell walls grew almost normally with bacterial staining only on the surface of stomata. These results indicate that the oat thionin effectively works in rice plants against bacterial attack.

Amino Acid Sequence↗