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Biomedical subjects

S Tanaka

Publications and source records attributed to S Tanaka.

At least 19 recordsLinked to original sources
PubMed2006

Structural transitions of the mono-olein bicontinuous cubic phase induced by inclusion of protein lysozyme solutions.

Inclusion of protein lysozyme molecules in the lipidic mono-olein cubic phase induces a transition from a Pn3m structure to an Im3m one. The small-angle x-ray scattering method with high-intensity synchrotron radiation enabled us to follow closely the transition depending on the conditions of lysozyme solutions. We show that concentrated lysozyme solutions induced the appearance of the Im3m structure coexisting with the Pn3m structure. From the relation between the lattice parameters of these two structures it is shown that they are related by the Bonnet transformation of the underlying triply periodic minimal surfaces. We found that the transition also occurred at lower lysozyme concentration when NaCl induced an attraction between lysozyme molecules. The origin of the transition was considered as a frustration in the cubic phase where lysozyme molecules were highly confined. A simple estimation of the frustration was given, which took into account the translational entropy of lysozyme molecules. At the highest concentration of lysozyme and NaCl the Im3m structure was found to disappear and left only the Pn3m structure. This was probably either due to the crystallization or phase separation of lysozyme solutions ongoing microscopically, which absorbed lysozyme molecules from channels of the cubic phase and thus removed the frustration.

Journal Article↗
PubMed2006

Laser-induced microexplosion confined in the bulk of a sapphire crystal: evidence of multimegabar pressures.

Extremely high pressures (approximately 10 TPa) and temperatures (5 x 10(5) K) have been produced using a single laser pulse (100 nJ, 800 nm, 200 fs) focused inside a sapphire crystal. The laser pulse creates an intensity over 10(14) W/cm2 converting material within the absorbing volume of approximately 0.2 microm3 into plasma in a few fs. A pressure of approximately 10 TPa, far exceeding the strength of any material, is created generating strong shock and rarefaction waves. This results in the formation of a nanovoid surrounded by a shell of shock-affected material inside undamaged crystal. Analysis of the size of the void and the shock-affected zone versus the deposited energy shows that the experimental results can be understood on the basis of conservation laws and be modeled by plasma hydrodynamics. Matter subjected to record heating and cooling rates of 10(18) K/s can, thus, be studied in a well-controlled laboratory environment.

Journal Article↗
PubMed2006

The usefulness of transabdominal ultrasound for the diagnosis of lower gastrointestinal bleeding.

BACKGROUND: Lower gastrointestinal bleeding is a frequent cause of hospitalization, but diagnostic methods for this condition are not fully established. Transabdominal ultrasound is a widely accepted diagnostic tool in bowel diseases. AIM: To evaluate the usefulness of transabdominal ultrasound for lower gastrointestinal bleeding. METHODS: We reviewed the medical records of consecutive patients who underwent transabdominal ultrasound as the first diagnostic procedure for acute haematochezia during the period June 1999 to June 2004. The study group comprised 111 patients and all underwent colonoscopy thereafter. Detection and diagnosis of lower gastrointestinal bleeding by ultrasonographic examination were evaluated by comparing the ultrasound diagnosis with the colonoscopic findings and final diagnosis. RESULTS: The bleeding site was localized by colonoscopy in 90 of the 111 patients (81%). The bleeding site was localized by ultrasound in 59 of the 90 patients (66%). When the bleeding site was in the rectum, ultrasonographic detectability was 30% (10/33); ultrasonographic detectability was 82-100% when the bleeding site was elsewhere. Rectal bleeding and diverticular bleeding were difficult to diagnose by ultrasound, but for the other diseases, diagnosis by ultrasonographic examination was possible in 91-100% of cases. CONCLUSIONS: Ultrasonographic examination may be an effective screening method for lower gastrointestinal bleeding.

Colon↗
PubMed2006

Sound alters activity in human V1 in association with illusory visual perception.

When a single brief visual flash is accompanied by two auditory bleeps, it is frequently perceived incorrectly as two flashes. Here, we used high field functional MRI in humans to examine the neural basis of this multisensory perceptual illusion. We show that activity in retinotopic visual cortex is increased by the presence of concurrent auditory stimulation, irrespective of any illusory perception. However, when concurrent auditory stimulation gave rise to illusory visual perception, activity in V1 was enhanced, despite auditory and visual stimulation being unchanged. These findings confirm that responses in human V1 can be altered by sound and show that they reflect subjective perception rather than the physically present visual stimulus. Moreover, as the right superior temporal sulcus and superior colliculus were also activated by illusory visual perception, together with V1, they provide a potential neural substrate for the generation of this multisensory illusion.

Acoustic Stimulation↗
PubMed2006

Gene expressions of canine angiopoietin-1 and -2 in normal tissues and spontaneous tumours.

The angiopoietin (Ang) family of proteins are central to the regulation of angiogenesis. The purposes of this study were to determine cDNA sequences of canine Ang-1 and Ang-2 and investigate their expressions in normal tissues and spontaneous tumours. The cDNA sequences of canine Ang-1 and Ang-2 were 1,494 and 1,488 bp, and the deduced amino acid sequences were 497 and 495 residues, respectively. The cDNA sequences of canine Ang-1 and Ang-2 showed high homology with those of the other mammalian species. Canine Ang-1 and Ang-2 mRNA were detectable in all 22 normal tissues and spontaneous tumours. Higher mRNA expression level of canine Ang-2 was demonstrated in mammary simple carcinomas, haemangiosarcoma and hepatocellular carcinoma in comparison with normal tissues.

Amino Acid Sequence↗
PubMed2006

Evaluation of tibial bone-tunnel changes with X-ray and computed tomography after ACL reconstruction using a bone-patella tendon-bone autograft.

Thirteen patients who underwent anterior cruciate ligament (ACL) reconstruction with bone-patella tendon-bone autografts (BTB) using interference screws were the subjects of this study. We analysed the relationship between bone-tunnel changes and clinical results 2 years after ACL reconstruction. To investigate changes, X-ray images were used to evaluate bone-tunnel enlargement, and computed tomography (CT) was used to evaluate the sclerotic area around the bone tunnel. The KT-2000 was used to measure the discrepancy of tibial anterior displacement between the affected and nonaffected sides (DTAD). There was no correlation between bone-tunnel enlargement and DTAD. On the other hand, in the CT evaluation, there was a significant correlation between the sclerotic area and DTAD. Our results suggest that it is more significant to analyse the area of sclerotic change than bone-tunnel enlargement for clinical evaluation. We cannot evaluate bone-tunnel changes correctly with two-dimensional X-rays and cannot analyse the sclerotic area using X-rays. Therefore, we recommend that CT, with which it is possible to analyse the sclerotic area, be used to evaluate bone-tunnel changes and clinical results.

Adult↗
PubMed2006

Involvement of adaptor protein Crk in malignant feature of human ovarian cancer cell line MCAS.

Signaling adaptor protein Crk regulates cell motility and growth through its targets Dock180 and C3G, those are the guanine-nucleotide exchange factors (GEFs) for small GTPases Rac and Rap, respectively. Recently, overexpression of Crk has been reported in various human cancers. To define the role for Crk in human cancer cells, Crk expression was targeted in the human ovarian cancer cell line MCAS through RNA interference, resulting in the establishment of three Crk knockdown cell lines. These cell lines exhibited disorganized actin fibers, reduced number of focal adhesions, and abolishment of lamellipodia formation. Decreased Rac activity was demonstrated by pull-down assay and FRET-based time-lapse microscopy, in association with suppression of both motility and invasion by phagokinetic track assay and transwell assay in these cells. Furthermore, Crk knockdown cells exhibited slow growth rates in culture and suppressed anchorage-dependent growth in soft agar. Tumor forming potential in nude mice was attenuated, and intraperitoneal dissemination was not observed when Crk knockdown cells were injected into the peritoneal cavity. These results suggest that the Crk is a key component of focal adhesion and involved in cell growth, invasion, and dissemination of human ovarian cancer cell line MCAS.

Actin Cytoskeleton↗
PubMed2006

IGF2 is critical for tumorigenesis by synovial sarcoma oncoprotein SYT-SSX1.

Synovial sarcoma is an aggressive soft tissue tumor characterized by a specific chromosomal translocation between chromosome 18 and X. This translocation can generate a fusion transcript encoding SYT-SSX1, a transforming oncoprotein. We present evidence that SYT-SSX1 induces insulin-like growth factor II expression in fibroblast cells. SYT-SSX2, a fusion also frequently found in synovial sarcoma, is necessary for maintaining Igf2 expression in the synovial sarcoma cell line, and the increased IGF2 synthesis protects cells from anoikis and is required for tumor formation in vivo. We also found a loss of imprinting (LOI) for Igf2 in a limited number of primary synovial sarcomas despite demethylation of CpG dinucleotides critical for maintaining imprinting. These findings suggest that inhibition of the IGF2/IGF1-R signaling pathway may represent a significant therapeutic modality for treating synovial sarcoma.

Animals↗
PubMed2006

Coherent control of charge and lattice dynamics in a photoinduced neutral-to-ionic transition of a charge-transfer compound.

Coherent control of a charge-lattice coupled oscillation associated with the neutral (N)-ionic (I) transition was successfully demonstrated for a charge-transfer (CT) compound, tetrathiafulvalene-p-chloranil, with use of double femtosecond laser pulses. By changing the interval of the two laser pulses, amplitude of the oscillation in the reflectivity for the intramolecular transition band sensitive to the degree of CT was periodically changed. With increase of the pump intensity, the oscillation amplitude was dramatically enhanced. Such an enhancement is discussed in terms of the cooperative nature of the N-I transition.

Journal Article↗
PubMed2006

Age-related emotionality is associated with cortical delta-opioid receptor dysfunction-dependent astrogliosis.

Multiple changes occur in the aging brain, leading to age-related emotional disorders. A growing body of recent evidence suggests that the cortical delta-opioid receptor system plays a critical role in anxiety- and depressive-like behaviors in the rodent. In this study, we show that aging mice promoted anxiety-like behaviors as characterized by both the light-dark and elevated plus-maze tests, and they exhibit an increase in astrocytes in the cingulate cortex due to the dysfunction of cortical delta-opioid receptor systems. As well as aging mice, mice with a dysfunction of the delta-opioid receptor system induced by chronic treatment with the selective delta-opioid receptor antagonist naltrindole, revealed astrogliosis in the cingulate cortex, which was associated with anxiety. We also found that the microinjection of cultured astrocytes into the cingulate cortex of young mice enhanced the expression of anxiety-like behavior. Our results indicate that the aging process promotes astrogliosis in the cingulate cortex through the dysfunction of cortical delta-opioid receptors. This phenomenon may lead to emotional disorders including aggravated anxiety during normal aging.

Aging↗
PubMed2006

Membrane orientation of the precursor 74-kDa form of L-histidine decarboxylase.

OBJECTIVE: We previously demonstrated that, when expressed in COS-7 cells, L-histidine decarboxylase (HDC), which has neither an amino terminal signal sequence nor a hydrophobic membrane anchor, was localized in the endoplasmic reticulum (ER), although its orientation in the membrane remains to be clarified. METHODS & RESULTS: Protease digestion and immunofluorescence analyses of the cells, of which plasma membrane was selectively permeabilized, revealed that the amino terminal 50-kDa portion of HDC is hardly accessible to proteases and antibodies added exogenously from the cytosolic side. Green fluorescent protein fused with the carboxyl terminal 20-kDa region of HDC at its carboxyl terminus exhibited the same characteristics as native HDC. CONCLUSION: These results indicate that HDC is tightly associated with the ER membrane with its carboxyl terminal region exposed on the cytosolic side.

Animals↗
PubMed2006

Endoscopic submucosal dissection for residual/local recurrence of early gastric cancer after endoscopic mucosal resection.

BACKGROUND AND STUDY AIMS: Endoscopic mucosal resection (EMR) is a widely accepted treatment for early gastric cancer; however, incomplete resection with residual local disease and recurrences continues to be a difficult problem. The aim of this study was to evaluate the efficacy and safety of endoscopic submucosal dissection (ESD) for residual/local recurrent early gastric cancer lesions after EMR. PATIENTS AND METHODS: The en bloc resection rate, histologically complete resection rate, complications, and local recurrence were assessed in 15 patients who underwent ESD for residual/local recurrent early gastric cancer lesions after EMR. RESULTS: The nonlifting sign after injection of a glycerin solution was positive due to scar formation in all cases. En bloc resection was attempted in all cases, with a complete resection rate of 93.3 % (14 of 15). The lesion was completely resected with histologically adequate margins in the 14 patients who received complete en bloc resection. The average operation time was 85.4 +/- 52.9 min, and the mean follow-up period for all patients was 18.1 +/- 7.4 months. Major bleeding during the procedure in one case was the only complication (one of 15, 6.7 %). None of the patients experienced recurrence of early gastric cancer after ESD. CONCLUSIONS: ESD appears to be a safe and effective treatment for residual/local recurrent early gastric cancer lesions after EMR, and it is useful for histological confirmation of successful treatment.

Aged↗
PubMed2006

Short communication: expression of human endogenous retrovirus-R gene links to differentiation of squamous cells.

To investigate the biological roles of human endogenous retrovirus-R (HERV-R) in vivo, we established transgenic rats carrying the full sequence of the viral genome with control of its own long terminal repeat promoter. The Env protein was expressed on the surface of the epidermis of fetal HERV-R transgenic rats on day 10 of gestation. The epidermal Env expression disappeared by day 18 of gestation. After day 18 of gestation, the Env protein was detected in the prickle layer of the esophageal epithelium of transgenic rats. Interestingly, it was not detected in the basal layer of the epithelium, and the expression in the granular layer was weaker than in the prickle layer. These findings suggest that expression of HERV-R is linked not only to the development but also to the differentiation of squamous cells. Next, we examined alterations in the expression of the HERV-R env gene in cultured human squamous cells after exposure to all-trans retinoic acids (ATRA). The env expression was increased by ATRA in a dose-dependent manner, while the expression of transglutaminase 1 (TGM1), a terminal marker for squamous differentiation, was decreased. TGM1 is expressed in the granular layer of the squamous epithelium, and ATRA suppresses the differentiation of cultured squamous cells. Thus, these in vitro data also suggest that HERV-R expression is regulated by a mechanism closely related to the differentiation of squamous cells. This study is the first to demonstrate the association of HERV-R expression and differentiation of squamous cells.

Animals↗
PubMed2006

Influence of proinflammatory cytokines on Actinobacillus actinomycetemcomitans specific IgG responses.

OBJECTIVE: High levels of serum anti-Actinobacillus actinomycetemcomitans immunoglobulin G (IgG) correlate with reduced extent and severity of periodontal disease and the present study was undertaken to begin testing the hypothesis that proinflammatory cytokines are important in the induction of optimal anti-A. actinomycetemcomitans IgG responses. BACKGROUND: Studies with pokeweed mitogen indicate that interleukin-1alpha (IL-1alpha) and IL-1beta are necessary for optimal IgG1 and IgG2 production and that prostaglandin E(2) (PGE(2)) and interferon-gamma (IFN-gamma) selectively promote IgG2, which is a major component of the anti-A. actinomycetemcomitans response in vivo. The pokeweed mitogen results suggest that these proinflammatory cytokines would also be necessary for optimal production of IgG specific for A. actinomycetemcomitans. METHODS: Peripheral blood mononuclear cells from A. actinomycetemcomitans-seropositive subjects with localized aggressive periodontitis were stimulated with A. actinomycetemcomitans in immune complexes capable of binding follicular dendritic cells that participate in the induction of recall responses in vivo. Cultures were manipulated with anti-IL-1alpha, anti-IL-1beta, anti-IFN-gamma, anti-IL-12, anti-CD21, indomethacin, and PGE(2). Actinobacillus actinomycetemcomitans specific IgG production was monitored by enzyme-linked immunosorbent assay (ELISA). RESULTS: Addition of follicular dendritic cells to peripheral blood mononuclear cells cultures resulted in follicular dendritic cell-lymphocyte clusters and increased anti-A. actinomycetemcomitans IgG responses (3-40-fold increases) compared with controls lacking follicular dendritic cells. Anti-IL-1alpha, anti-IL-1beta, anti-IFN-gamma, anti-IL-12, anti-CD21 and indomethacin suppressed anti-A. actinomycetemcomitans IgG production by half or more. PGE(2) restored IgG responses suppressed by indomethacin. CONCLUSIONS: The cytokines IL-1alpha, IL-1beta, IFN-gamma, IL-12, and PGE(2) were all necessary for optimal production of human anti-A. actinomycetemcomitans and the need for proinflammatory cytokines including the T helper 1 (Th1) cytokines is consistent with a response with a significant IgG2 component.

Actinobacillus Infections↗