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Biomedical subjects

Hiroaki Takeuchi

Publications and source records attributed to Hiroaki Takeuchi.

At least 37 records · Page 2Linked to original sources
PubMed2006

Atlas hypoplasia associated with non-traumatic retro-odontoid mass.

A 38-year-old man presented with progressive cervical myelopathy due to atlas hypoplasia associated with non-traumatic retro-odontoid mass. The neuroimaging findings suggested hypertrophy of the transverse ligament of the atlas. No histological confirmation of the retro-odontoid mass was obtained. Clinical manifestations improved after posterior decompression. Decompressive laminectomy of the atlas with or without fusion can achieve a good outcome in such cases.

Adult↗
PubMed2006

Study of the clinical usefulness of a dental drug system for selective reduction of mutans streptococci using a case series.

The aim of this study was to evaluate the clinical efficacy and safety of a dental drug delivery system (3DS) for the selective reduction of mutans streptococci. Twenty patients with high levels of mutans streptococci in saliva participated. The efficacy of 0.2% chlorhexidine (CHX) delivered by 3DS in reducing the salivary levels of mutans streptococci compared with total streptococci and lactobacilli was investigated. Each subject was treated by professional mechanical tooth cleaning (PMTC) and subsequently individual trays with CHX for 5 min. Salivary bacterial samples were taken at the baseline and weeks 1-12. A significant reduction in the colony count of mutans streptococci was observed during the first 4 weeks compared with the baseline count, while no significant decrease in the count of total streptococci or lactobacilli was found during 12 weeks. In particular, the proportion of mutans streptococci in total streptococci remained low after 12 weeks. Our results indicate that the new 3DS used in combination with PMTC appears to be a promising intraoral drug delivery system which, when used with a low CHX concentration selectively, effectively reduces mutans streptococci in the oral cavity with no adverse effects.

Adult↗
PubMed2006

Mild hypothermia promotes pro-inflammatory cytokine production in monocytes.

Hypothermia is often associated with compromised host defenses and infection. Deteriorations of immune functions related to hypothermia have been investigated, but the involvement of cytokines in host defense mechanisms and in infection remains unclear. We have previously shown that mild hypothermia modifies cytokine production by peripheral blood mononuclear cells. In this study, the effects of hypothermia on the monocytic production of several cytokines and nitric oxide (NO) were determined. Monocytes obtained from 10 healthy humans were cultured with lipopolysaccharide (LPS) under hypothermic (33 degrees C) or normothermic (37 degrees C) conditions for 48 hours. We performed flow cytometric analysis for simultaneous measurement of interleukin (IL)-8, IL-1beta, IL-6, IL-10, IL-12p70, and tumor necrosis factor (TNF)-alpha in culture supernatants. NO production was quantified as accumulation of nitrite in the medium by a colorimetric assay. Compared with normothermia, mild hypothermia raised the levels of IL-1beta, IL-6, IL-12p70, and TNF-alpha produced by monocytes stimulated with LPS. On calculating the ratios of these elevated cytokines to IL-10, however, only IL-12p70/IL-10 and TNF-alpha/IL-10 ratios were significantly elevated under hypothermic conditions. In contrast, hypothermia did not affect NO production. This study demonstrates that mild hypothermia affects the balance of cytokines produced by monocytes, leading to a pro-inflammatory state. Specifically, monocytic IL-12 and TNF-alpha appear to be involved in the immune alterations observed in mild hypothermia. However, the clinical significance of these phenomena remains to be clarified.

Adult↗
PubMed2005

A new diagnostic assay for glycogen storage disease type II in mixed leukocytes.

We have established a new method for the enzymatic diagnosis of glycogen storage disease type II (Pompe disease or acid maltase deficiency) using mixed leukocytes. The method employs glycogen and 4-methylumbelliferyl-alpha-D-glucopyranoside (4MU-alphaGlc) as substrates for measuring the lysosomal acid alpha-glucosidase (acid alphaGlu) activity, and incorporates acarbose to eliminate the interference of unrelated alpha-glucosidases (predominantly maltase-glucoamylase). It is shown that 3.0 micromol/L acarbose completely inhibits the maltase-glucoamylase activity at pH 4.0, but the lysosomal acid alphaGlu activity by less than 5%. With this method, we determined the acid alphaGlu activity in mixed leukocytes from 25 patients with glycogen storage disease type II (2 infantile and 23 late-onset cases), one GAA2/GAA2 homozygote and 30 healthy subjects. In the assay with glycogen as substrate, the addition of acarbose created a clear separation between the patient and the control ranges. In the assay with 4MU-alphaGlc as substrate, the two ranges were fully separated but remained very close despite the use of acarbose. The separation of the patient and normal ranges was improved considerably by taking the ratio of acarbose-inhibited over uninhibited activity. A GAA2/GAA2 homozygote was correctly diagnosed with 4MU-alphaGlc but misdiagnosed as patient when glycogen was used as substrate. We conclude that the inclusion of 3.0 micromol/L acarbose in the assays with glycogen and 4MU-alphaGlc substrates at pH 4.0 allows for the specific measurement of lysosomal acid alphaGlu activity in mixed leukocytes, thus enabling a reliable diagnosis of glycogen storage disease type II in this specimen.

Acarbose↗
PubMed2005

Absence of orbito-ocular signs in dural carotid-cavernous sinus fistula with a prominent anterior venous drainage.

A 55-year-old woman developed an intractable right orbitofrontal headache. The symptoms subsided spontaneously 2 months after onset, but diplopia due to right abducens nerve palsy had occurred, and gradually worsened. Orbito-ocular signs were never observed throughout the clinical course. Brain MRI and MR angiography demonstrated abnormal signal changes corresponding to the right cavernous sinus. Angiography confirmed a dural carotid-cavernous sinus fistula (CCF) with three directional drainage routes in the arterial phase. Although the most prominent draining vein was the superior ophthalmic vein (SOV), an outflow with a high flow rate into the angular facial vein prevented prolonged enhancement of the SOV in the venous phase. These findings suggest that the absence of orbito-ocular signs in dural CCF with an anterior venous drainage could be attributed to the relief of venous hypertension of the SOV.

Angiography↗
PubMed2005

Low-dose tacrolimus for two cases of myasthenia gravis with invasive thymoma that relapsed shortly after thymectomy.

Two patients with myasthenia gravis (Ossermann IIb) involving invasive thymoma who underwent extensive thymectomy manifested myasthenic crisis shortly after the procedure; however, both patients were treated with intravenous immunoglobulin and recovered from myasthenic crisis that had been deteriorating for about 1 week. Subsequently, the patients were administered a low-dose of tacrolimus (3 mg/day) in addition to prednisolone. Several months later, tacrolimus continued to control fluctuations of myasthenic symptoms and maintained remission in these patients. The serum titer of anti-Ach-receptor antibodies decreased in parallel with clinical improvement due to tacrolimus, and we accordingly reduced the dosage of prednisolone. Tacrolimus is a new immunosuppressive agent acting through the selective inhibition of helper-T-cell activation that can be reduced dosage of steroids and can maintain remission of myasthenia gravis with invasive thymoma.

Adult↗
PubMed2005

Interferons upregulate thymidine phosphorylase expression via JAK-STAT-dependent transcriptional activation and mRNA stabilization in human glioblastoma cells.

Overexpression of the angiogenic enzyme thymidine phosphorylase (TP) in tumor cells and/or infiltrating macrophages correlates with increased microvessel density and poor prognosis in various tumor types including glioma. The present study examined how the TP gene expression is regulated by different types of interferons (IFNs) in human T98G and A172 glioblastoma cells. Both type I (alpha, beta) and type II (gamma) IFNs upregulated TP mRNA and protein expression while inhibiting cell proliferation. IFN-induced TP mRNA accumulation was not inhibited by the protein synthesis inhibitor cycloheximide, but was strongly blocked by the transcription inhibitor actinomycin D, as well as by transcription factor decoy oligodeoxynucleotides containing the putative IFN response element or the gamma-activated sequence in the TP promoter. The Janus kinase (JAK) inhibitor AG-490 blocked both IFN-induced STAT1 (signal transducers and activators of transcription 1) phosphorylation and TP expression. All IFNs increased the stability of TP mRNA as well. In addition, IFN-evoked TP enzyme activity enhanced the cytotoxicity of 5-fluorouracil (5-FU). These findings indicate that TP expression may be upregulated by IFNs via the JAK-STAT signaling pathway and both transcriptional and posttranscriptional mechanisms. Combined treatment with IFN and 5-fluorouracil may be a useful therapeutic strategy for malignant gliomas.

Antimetabolites, Antineoplastic↗
PubMed2005

Suppression of human immunodeficiency virus type 1 (HIV-1) replication by an HIV-1-dependent double locked vector with the Cre/loxP system.

We previously demonstrated the function of an HIV-1-dependent ribozyme expression vector, with which the site-specific excision of loxP sequences can be achieved by using the Cre-loxP system (ON/OFF) as a molecular switch in an acute HIV-1 infection. However, this expression system also revealed the lower, non-specific expression of the anti-H1V-1 ribozyme in the absence of tat. To circumvent this problem, we used the more efficient HIV-1-dependent Cre recombinase gene expression vector, encoding the LTR-gag-p17 (extending from the 5'-LTR to the middle of the gag gene (pLTR-gag-p17-Cre)). Comparatively, the pLTR-gag-p17-Cre induces a higher Cre-protein expression level in an HIV-1 infection-dependent manner than the minimal pLTR-Cre. Furthermore, we constructed the ploxP-Rz-U5 and pLTR-gag-p17-Cre plasmids and also combined them into a single vector, pLTR-gag-p17-Cre/loxP-Rz-U5, for a comparison of their anti-HIV-1 activities. The resultant simultaneous expression of the Cre protein and the homologous recombination of the two loxP sequences induced a high level of HIV-1 replication inhibition (95%). Significantly, a high steady-state of ribozyme expression was observed in the RT-PCR analysis. These data imply that targeting the HIV-1 genes with the pLTR-gag-p17-Cre/loxP-Rz-U5 vector, which mediates HIV-1-dependent ribozyme expression, would be a useful tool for HIV-1 gene therapy applications.

Gene Expression↗
PubMed2005

Prognostic significance of microvessel density determined by an anti-CD105/endoglin monoclonal antibody in astrocytic tumors: comparison with an anti-CD31 monoclonal antibody.

There are conflicting reports as to whether the degree of angiogenesis as measured by microvessel density (MVD) has a prognostic value in astrocytic tumors. This may be due to the use of different antibodies against endothelial cells to highlight microvessels. It has been reported that unlike pan-endothelial antibodies, such as CD31, anti-CD105 antibodies preferentially react with endothelial cells in angiogenic tissues. To clarify the validity of anti-CD105 antibody in the evaluation of angiogenesis, we assessed MVD using an anti-CD105 monoclonal antibody (mAb) (CD105-MVD) and an anti-CD31 mAb (CD31-MVD) in a series of 50 astrocytic tumors, and correlated MVD with expression of the key angiogenic factor vascular endothelial growth factor (VEGF) and prognosis. The mean CD31-MVD and CD105-MVD was 36.7 and 24.8 for low-grade astrocytoma (LGA), 48.0 and 42.7 for anaplastic astrocytoma, 55.3 and 51.9 for glioblastoma multiforme (GBM), respectively. CD105-MVD was more closely correlated with VEGF expression than CD31-MVD. Patients with LGA and GBM showing higher CD105-MVD had a significantly shorter mean survival time (MST) than those with lower CD105-MVD tumors (P = 0.0381 and 0.0131, respectively). Whereas the MST of patients with higher CD31-MVD tumors seemed to be shorter than that of lower CD31-MVD patients within each tumor grade, the differences were not statistically significant. These findings suggest that anti-CD105 mAb may be a better marker than anti-CD31 mAb in evaluation of angiogenesis and prediction of prognosis in astrocytic tumors.

Adolescent↗
PubMed2005

Viral RNA is required for the association of APOBEC3G with human immunodeficiency virus type 1 nucleoprotein complexes.

APOBEC3G (APO3G) is a host cytidine deaminase that is incorporated into human immunodeficiency virus type 1 (HIV-1) particles. We report here that viral RNA promotes stable association of APO3G with HIV-1 nucleoprotein complexes (NPC). A target sequence located within the 5'-untranslated region of the HIV-1 RNA was identified to be necessary and sufficient for efficient APO3G packaging. Fine mapping revealed a sequence normally involved in viral genomic RNA dimerization and Gag binding to be important for APO3G packaging and association with viral NPC. Our data suggest that packaging of APO3G into HIV-1 NPC is enhanced by viral RNA.

5' Untranslated Regions↗
PubMed2005

[Clinical usefulness of B-flow imaging in the diagnosis of superficial soft tissue tumors].

B-flow imaging is a recently developed ultrasound technique that extends the B-mode imaging quality of blood flow, including high-frame-rate and high-spatial-resolution imaging. The purpose of the present study was to clarify the usefulness of B-flow for evaluation of the hemodynamics of superficial soft tissue tumors. All 33 cases of superficial soft tissue tumors were examined by both B-flow and Color/Power Doppler methods on the same plane. The B-flow images that were obtained were evaluated by comparison with corresponding Color/Power Doppler images. The following four items were compared and evaluated: (1) sensitivity to the detection of tumor vessels; (2) quality of background B-mode imaging; (3) frame rate; and (4) spatial resolution of tumor vessels. B-flow was somewhat inferior to Color/Power Doppler imaging in sensitivity to the detection of tumor vessels. B-flow was clearly inferior in the quality of background B-mode imaging. B-flow provided high-frame-rate imaging. The diameter of tumor vessels on B-flow imaging was clearly thinner than that on Color/Power Doppler images and appeared to indicate the true diameter of tumor vessels. By providing high-frame-rate imaging and high spatial resolution, B-flow makes it possible to clarify the precise vascular structure.

Blood Flow Velocity↗
PubMed2004

Production of infectious SIVagm from human cells requires functional inactivation but not viral exclusion of human APOBEC3G.

The virus infectivity factor (Vif) is a protein encoded by most primate lentiviruses. Recent evidence suggests that HIV-1 Vif reduces the intracellular levels of the host cytidine deaminase APOBEC3G (Apo3G) and inhibits its packaging into virions. These functions of Vif are thought to be species-specific. Accordingly, HIV-1 Vif can target only human Apo3G (hApo3G), whereas, African green monkey simian immunodeficiency virus (SIVagm) Vif can inhibit African green monkey but not human Apo3G. Consistent with this, we found that SIVagm Vif does not affect the stability of exogenously and endogenously expressed hApo3G and does not prevent packaging of exogenous and endogenous hApo3G into SIVagm virions. Nevertheless, SIVagm Vif supported spreading infection of SIVagm virus in the hApo3G-positive human A3.01 T cell line and rescued infectivity of viruses produced from Apo3G-expressing HeLa cells. Sequence analysis verified that SIVagm Vif inhibited the accumulation of hApo3G-induced mutations, suggesting that SIVagm Vif is indeed active in human cells. Our data suggest that SIVagm Vif can inhibit hApo3G activity without inducing its intracellular degradation or preventing its packaging into virions.

APOBEC-3G Deaminase↗
PubMed2004

Production of infectious human immunodeficiency virus type 1 does not require depletion of APOBEC3G from virus-producing cells.

BACKGROUND: The human immunodeficiency virus Vif protein overcomes the inhibitory activity of the APOBEC3G cytidine deaminase by prohibiting its packaging into virions. Inhibition of APOBEC3G encapsidation is paralleled by a reduction of its intracellular level presumably caused by the Vif-induced proteasome-dependent degradation of APOBEC3G. RESULTS: In this report we employed confocal microscopy to study the effects of Vif on the expression of APOBEC3G on a single cell level. HeLa cells dually transfected with Vif and APOBEC3G expression vectors revealed efficient co-expression of the two proteins. Under optimal staining conditions approximately 80% of the transfected cells scored double-positive for Vif and APOBEC3G. However, the proportion of double-positive cells observed in identical cultures varied dependent on the fixation protocol and on the choice of antibodies used ranging from as low as 40% to as high as 80% of transfected cells. Importantly, single-positive cells expressing either Vif or APOBEC3G were observed both with wild type Vif and a biologically inactive Vif variant. Thus, the lack of APOBEC3G in some Vif-expressing cells cannot be attributed to Vif-induced degradation of APOBEC3G. These findings are consistent with our results from immunoblot analyses that revealed only moderate effects of Vif on the APOBEC3G steady state levels. Of note, viruses produced under such conditions were fully infectious demonstrating that the Vif protein used in our analyses was both functional and expressed at saturating levels. CONCLUSIONS: Our results suggest that Vif and APOBEC3G can be efficiently co-expressed. Thus, depletion of APOBEC3G from Vif expressing cells as suggested previously is not a universal property of Vif and thus is not imperative for the production of infectious virions.

APOBEC-3G Deaminase↗
PubMed2004

Painful legs and moving toes syndrome associated with herpes zoster myelitis.

A 75-year-old woman developed painful legs and moving toes syndrome (PLMT) 16 months after the onset of herpes zoster (HZ) myelitis. Although the scattered extensive lesions due to HZ myelitis were observed to be eccentric near the posterior horn on MRI, these changes had disappeared upon the development of PLMT. Combined median and tibial nerve somatosensory evoked potentials demonstrated abnormal findings only in the tibial nerve stimuli, suggesting that a severe alteration occurred in the somatosensory fibers coming selectively from the lower legs. These findings suggest plasticity in the ascending somatosensory pathway including the posterior horn cells, probably involving the interneuron networks, for the lower legs may underlie the development of PLMT associated with HZ myelitis.

Aged↗
PubMed2004

The study of cytopathological aspects induced by human cytomegalovirus infection.

In cytological examination, human cytomegalovirus (HCMV) infection can not be implied unless typical HCMV-infected cells like owl's-eye cells are present. However, such cells are not always observed in HCMV-infection cases. The aim of our study is to establish the cytopathological features induced by HCMV. In vitro transfection and fluorescence in situ hybridization (FISH) were performed on human embryo lung (HEL) cells. Marked cellular aggregation was observed at 6-hr postinfection (hpi). Multinucleated cells, giant cells, and, particularly, small vacuoles were present in the nuclei or cytoplasm before the appearance of inclusion bodies. However, molding and ground glass in nuclei were absent. Cell clusters displayed round cytoplasm, dispersed later, and showed anisocytosis. All features occurred before 48 hpi when the owl's-eye cell appeared. In FISH, the positive signal highlighted viral particles that became predominant and localized in nuclei. These cytological aspects are dependent on viral replication and contribute to the cytological detection of HCMV infection.

Cell Aggregation↗
PubMed2004

Ultrastructure of capillary endothelium in pilocytic astrocytomas.

The aim of this study was to assess the capillary ultrastructure of pilocytic astrocytomas with gadolinium contrast enhancement on magnetic resonance imaging (MRI). Cysts were identified in all cases with pilocytic astrocytoma. Histological investigation focusing on the vascular structure was performed by light microscopy and electron microscopy in four pilocytic astrocytomas. In the pilocytic astrocytomas, light microscopic examination demonstrated vascular abnormalities (fibrosis, hyalinization, and vascular proliferation), and electron microscopic examination revealed fenestration and vesicles in the capillary endothelium. Fenestration of the vessels and vascular abnormalities with degeneration are suggested to develop both contrast enhancement on neuroimaging and cystic formation in pilocytic astrocytomas.

Adolescent↗
PubMed2004

A case of graft infection 10 years after ascending aorta replacement.

A 52-year-old man was admitted with anemia and slight fever, which he had for the last 2 months. He had undergone replacement of the ascending aorta for acute aortic dissection 10 years previously. Echocardiography demonstrated a flailing thin structure in the anterior wall of the ascending aorta corresponding to the proximal portion of the prosthetic graft. This abnormal echocardiographic finding led us to repeat blood cultivation. We finally detected Enterococcus facium and Staphylococcus epidermidis in his blood sample. We diagnosed this as a graft infection and prepared for surgical re-replacement of the infected graft. While he was waiting for the operation, an infectious aneurysm of a tibialis posterior artery ruptured and an emergency operation was done. Replacement of the infected ascending aorta graft was done thereafter. In surgery, 2-cm-long vegetation was found. It stuck to the graft wall near the former hole used for air removal in the first surgery. The patient recovered fully and left our hospital after 3 months of postoperative antibiotics therapy. This rare case of aortic graft infection long after the original replacement surgery suggests the importance of thorough echocardiographic investigation of prosthetic graft infection as a possible cause of fever of unknown origin.

Aneurysm↗