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Biomedical subjects

T Hatano

Publications and source records attributed to T Hatano.

At least 19 recordsLinked to original sources
PubMed2005

Single-electron delocalization in hybrid vertical-lateral double quantum dots.

We used a hybrid vertical-lateral double-dot device, consisting of laterally coupled vertical quantum dots, to measure the interdot tunnel coupling. By using nonlinear transport measurements of "Coulomb diamonds," we showed that an inherent asymmetry in the capacitances of the component dots influences the diamond slopes, thereby allowing for the determination of the dot through which the electron has passed. We used this technique to prepare a delocalized one-electron state and Heitler-London (HL) two-electron state, and we showed that the interdot tunnel coupling, which determines whether HL is the ground state, is tunable. This implies that our device may be useful for implementing two-electron spin entanglement.

Journal Article↗
PubMed2005

Surgical treatment for bilateral carotid arterial stenosis.

Carotid endarterectomy (CEA) is a beneficial procedure for patients with high-grade carotid stenosis. However, patients with bilateral carotid stenosis have a higher surgical risk during CEA. Since the introduction of carotid stenting (CAS) may decrease some of the surgical complications of CEA, a combined treatment using CEA and CAS may be favorable for patients with bilateral carotid stenosis. We analyzed the safety and efficacy of this treatment strategy. Eighteen patients with bilateral carotid stenosis were treated from January 2000. Bilateral CEA was performed on the first two patients, CAS then CEA of contra-lateral symptomatic side in 13 patients, and bilateral CAS in three patients. There were no perioperative neurological complications or strokes during the follow-up period (mean 17 months). The combined treatment of CAS and CEA was a safe and effective strategy for bilateral carotid stenosis.

Aged↗
PubMed2005

Stenting for vertebrobasilar artery stenosis.

We report our experience with stenting for symptomatic vertebrobasilar artery stenosis. One hundred and sixteen patients with vertebrobasilar artery stenosis (101 vertebral ostial stenosis, 15 intracranial vertebrobasilar artery stenosis) were treated with stenting. Indication criteria of treatment were 1) symptomatic lesion, 2) angiographical stenosis more than 60%. Under local anesthesia, pre-dilatation was first performed, then stents were placed to the lesion. Successful dilatation was obtained in 115 cases. The stenosis rate reduced to 2% post-stenting in ostial lesions and 16% in intracranial lesions. Transient neurological complications developed in 2 patients. Follow-up angiographies more than 6 months after stenting were performed in 94 patients with ostial lesions and all patients with intracranial lesions. Of these, 8 patients (9.5%) with ostial lesions and 4 patients (27%) with intracranial lesions developed restenosis. All patients with restenosis were treated successfully with PTA (percutaneous transluminal angioplasty). During the follow-up period, 3 patients developed recurrence of VBI (vertebro-basilar insufficiency) symptoms due to restenosis. One patient developed brain stem infarction due to in-stent occlusion 8 months after stenting. Conclusion. Stenting for vertebrobasilar artery stenoses is feasible and safe. Prevention of restenosis, especially in intracranial arteries, is the next problem to be solved.

Aged↗
PubMed2004

Electron-spin and electron-orbital dependence of the tunnel coupling in laterally coupled double vertical dots.

We employ a new laterally coupled, vertical double dot with a tunable tunnel-coupling gate in a parallel configuration to study the electron spin and orbital dependence of quantum mechanical tunnel coupling on the size of the honeycomb vertices in the small electron numbers regime. We find a transition from the weak coupling regime, where fluctuations in tunnel coupling due to varying electron configuration dominate the anticrossings, to a regime where the two dots coalesce. We apply a magnetic field to ascertain the orbital angular momenta of the Fermi surface eigenstates, which correlate with anticrossing size, and we identify spin pairs with congruent behavior.

Journal Article↗
PubMed2004

Single-dot spectroscopy via elastic single-electron tunneling through a pair of coupled quantum dots.

We study the electronic structure of a single self-assembled InAs quantum dot by probing elastic single-electron tunneling through a single pair of weakly coupled dots. In the region below pinch-off voltage, the nonlinear threshold voltage behavior provides electronic addition energies exactly as the linear, Coulomb blockade oscillation does. By analyzing it, we identify the s and the p shell addition spectrum for up to six electrons in the single InAs dot, i.e., one of the coupled dots. The evolution of the shell addition spectrum with magnetic field provides Fock-Darwin spectra of the s and p shells.

Journal Article↗
PubMed2003

Cervical dystonia in dentatorubral-pallidoluysian atrophy.

Hereditary dentatorubral-pallidoluysian atrophy (DRPLA) is a rare autosomal-dominant neurodegenerative disease characterized by variable clinical phenotypes. Its characteristic clinical manifestations include ataxia, choreoathetotic movements, seizures, myoclonus and dementia, but cervical dystonia has been rarely reported. Here we report a family with DRPLA who presented with cervical dystonia. The proband was a 66-year-old woman. Cervical dystonia was the initial and the most prominent symptom, and mild cerebellar signs and choreic movements were also observed. DNA analysis revealed expanded trinucleotide repeats within the DRPLA gene. The daughter of the proband, a 29-year-old woman, also had cervical dystonia for 3 years. Cranial magnetic resonance imaging showed a mild atrophy of the brainstem and the cerebellum in both of these patients. DRPLA should be considered in the differential diagnosis of patients presenting with cervical dystonia.

Adult↗
PubMed2002

Radiation-induced cerebral aneurysm successfully treated with endovascular coil embolization.

In a 30-year-old male, multiple cerebral aneurysms developed 19 years after receiving 60 Gy of irradiation for craniophariginoma. Angiogram revealed right IC-PC and upper basilar trunk aneurysms in addition to atherosclerotic change. The right IC-PC aneurysm was wrapped and the basilar trunk aneurysm located between the origins of SCA and AICA was treated by endovascular coil embolization. The packing of the aneurysm was complete, but stenosis of the basilar artery appeared. The patient was discharged uneventfully and follow-up angiogram 6 months later demonstrated that the aneurysm had disappeared and the patency of the basilary artery had been preserved. Radiation-induced intracranial vasculopathy is a well-recognized phenomenon, but aneurysm formation is less common than arterial occlusive lesion. However, the mortality rate after bleeding is so high that immediate diagnosis and treatment by direct surgery or coil embolization are necessary.

Adult↗
PubMed2002

Pseudouridine, an antimutagenic substance in beer towards N-methyl-N'-nitro-N-nitrosoguanidine (MNNG).

Previously we reported that beer is antimutagenic against several food-derived mutagens including heterocyclic amines. We describe here the isolation and identification of pseudouridine from beer as an antimutagenic substance against N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). All of the 17 samples of beer tested showed inhibition of the MNNG mutagenicity in Salmonella. Extensive fractionation through chromatography of the active components from a freeze-dried beer sample gave six antimutagenic fractions. One contained pseudouridine, as characterized by the UV spectra, nuclear magnetic resonance, and co-chromatography in HPLC. Pure pseudouridine inhibited the mutagenicity of MNNG in a dose-dependent manner. The amount of pseudouridine in the beer sample, estimated at about 0.4 mg/100 ml beer, can account for 3% of the total antimutagenicity of beer. Thus, the major active components in beer remain to be identified. The role of pseudouridine in inhibiting the mutagenicity of MNNG is to be studied further. Among analogs of pseudouridine, spongouridine, but not uridine, was antimutagenic against MNNG. The bacterial mutagenicity of another methylating agent N-methyl-N-nitrosourea was also inhibited by pseudouridine. Pseudouridine is the first example among nucleosides to be shown to possess an antimutagenic property.

Antimutagenic Agents↗
PubMed2001

Prostate-specific antigen induces osteoplastic changes by an autonomous mechanism.

The high prevalence of osteoplastic bone metastasis in prostate cancer (PC) is believed to be attributable to the production of osteoblast-stimulating factors by PC cells. Prostate-specific antigen (PSA) is a serine protease and an important serological marker for PC. Exposure of osteoblasts to PSA in vitro was found to result in cell proliferation and marked upregulation of transforming growth factor-beta (TGF-beta) mRNA expression. This PSA-induced increase in osteoblast proliferation was inhibited by anti-TGF-beta antibodies and serine protease inhibitors. In vivo, PSA markedly enhanced osteoplastic changes in human adult bone implanted into NOD/SCID mice without PC cells, and alpha(1)-antichymotrypsin prevented the PSA-induced increase in bone volume. PSA promotes osteoplastic change by activating an osteoblast autonomous mechanism that is independent of the production of bone growth factors by PC cells.

Aged↗
PubMed2001

Steady-state thermodynamics of Langevin systems.

We study Langevin dynamics describing nonequilibirum steady states. Employing the phenomenological framework of steady-state thermodynamics constructed by Oono and Paniconi [Prog. Theor. Phys. Suppl. 130, 29 (1998)], we find that the extended form of the second law which they proposed holds for transitions between steady states and that the Shannon entropy difference is related to the excess heat produced in an infinitely slow operation. A generalized version of the Jarzynski work relation plays an important role in our theory.

Journal Article↗
PubMed2001

Establishment of a novel species- and tissue-specific metastasis model of human prostate cancer in humanized non-obese diabetic/severe combined immunodeficient mice engrafted with human adult lung and bone.

Bone is the most common site of metastasis in prostate cancer (PC), and to generate an animal model to investigate the basis of the unique organ tropism of PC cells for bone, we engrafted humanized non-obese diabetic/severe combined immunodeficient (NOD/SCID-hu) mice with human adult bone (HAB) and lung (HAL). Human PC cell lines LNCaP (1 x 10(7)) and PC-3 (5 x 10(6)) were injected into male NOD/SCID-hu mice via the lateral tail vein at 3-4 weeks after implantation. At 8 weeks after the injection, LNCaP and PC-3 cells had metastasized specifically to HAB in 35 and 65%, respectively, of the mice. The tumors formed by LNCaP appeared to be the osteoblastic type, whereas the PC-3 tumors consisted of osteolytic lesions without any surrounding osteogenic response. A feature of experimental metastasis of PC in NOD/SCID-hu mice was its specificity for HAB tissue. Human PC cells had no or very low metastatic potential in regard to implanted HAL, mouse bone, or native mouse bone. These findings indicate that metastasis of PC cells to HAB is both species and tissue specific. The availability of this small animal model could provide a useful tool for identifying and analyzing important features of the human PC metastatic process that cannot be addressed in conventional metastasis models.

Aged↗
PubMed2001

Megastigmane glycosides and an acylated triterpenoid from Eriobotrya japonica.

Two new megastigmane glycosides, eriojaposides A (1) and B (2), and a new acylated triterpenoid (3) were isolated along with nine known compounds from a leaf extract of Eriobotrya japonica. The structures of 1--3 were characterized as (6R,9R)-3-oxo-alpha-ionyl-9-O-beta-xylopyranosyl-(1' '-->6')-beta-glucopyranoside, (6R,9R)-3-oxo-alpha-ionyl-9-O-alpha-rhamnopyranosyl-(1' '-->6')-beta-glucopyranoside, and 3 alpha-trans-feruloyloxy-2 alpha-hydroxyurs-12-en-28-oic acid, respectively, on the basis of spectral and chemical evidence.

Asia↗
PubMed2001

Glyoxylate determination in rat urine by capillary electrophoresis.

Oxalate is important in the study of renal stone formation and is derived from the endogenous metabolism of glyoxylate. The aim of this study was to determine urinary glyoxylate levels by capillary electrophoresis (CE). Urine specimens were obtained from 25 male Wistar rats (16 rats intravenously injected with 10 mg or 20 mg glyoxylate and nine controls) by bladder puncture 1 h after administration of glyoxylate or saline. Urinary glyoxylate was measured by CE using an electrolyte composed of 5 mmol/L pyridinedicarboxylic acid and 0.5 mmol/L cetyltrimethylammonium bromide (pH 5.6 and 11.0). The mean +/- SD urinary glyoxylate concentration was 43.1 +/- 14.7 micromol/L in control rats, 722.8 +/- 165.5 micromol/L in rats given 10 mg of glyoxylate and 1290.0 +/- 470.8 micromol/L in rats given 20 mg of glyoxylate. The mean +/- SD recovery after spiking 675.7 micromol/L of glyoxylate into 16 urine specimens was 98.82 +/- 12.81%. When the reproducibility of urinary glyoxylate determination was assessed, the intra-assay coefficient of variation (CV) ranged from 1.38 to 2.59% and the inter-assay CV ranged from 2.94 to 6.69%. Capillary electrophoresis enables sensitive and reproducible determination of urinary glyoxylate levels in rats. This method appears to be suitable for laboratory use and has the advantage of determining glyoxylate and several other urinary anions simultaneously.

Animals↗
PubMed2001

Transitional cell carcinoma of the renal pelvis forming tumor thrombus in the vena cava.

A 47-year-old man presented with a left renal incidentaloma without hematuria. The tumor was complicated by inferior vena cava (IVC) thrombus extending from Th11 to L4. A temporary IVC filter was introduced prior to surgery. A midline incision was used to perform a left radical nephrectomy and en bloc lymphadenectomy with excision of the inferior vena cava from above the level of the left renal vein to 2.5 cm above the confluence of the common iliac veins. The pathological diagnosis was invasive transitional cell carcinoma. The tumor thrombus consisted of transitional cell carcinoma that histologically invaded the walls of the IVC. He died of cancer 17 months after the operation for the liver metastases. This is the 18th case report of such a presentation in the literature.

Carcinoma, Transitional Cell↗
PubMed2001

Antileishmanial activity of hydrolyzable tannins and their modulatory effects on nitric oxide and tumour necrosis factor-alpha release in macrophages in vitro.

A series of 27 hydrolyzable tannins and related compounds was tested for antiparasitic effects against both extracellular promastigote and intracellular amastigote Leishmania donovani organisms. In parallel, the compounds were evaluated for their immunomodulatory effects on macrophage functions, including release of nitric oxide (NO), tumour necrosis factor-alpha (TNF-alpha) and interferon (IFN)-like properties using several functional assays. Of the series of polyphenols tested, only gallic acid (54 microM NO) and its methyl ester (32 microM NO) induced murine macrophage-like RAW 264.7 cells to release NO in appreciable amounts (IFN-gamma/LPS 119 microM NO). The in vitro TNF-inducing potential of the polyphenols examined increased in the order of oligomeric ellagitannins (EC(50) > 25 microg/ml) < monomeric ellagitannins, gallotannins (EC(50) 8.5 to > 25 microg/ml) < C-glucosidic ellagitannins, dehydroellagitannins (EC(50) 0.6 - 2.8 microg/ml) at the host cell subtoxic concentration of 50 microg/ml. Furthermore, promastigotes of Leishmania donovani were assayed in the presence of these polyphenols and the results showed that none of the compounds was significantly toxic (EC(50) > 25 microg/ml) to the extracellular forms. In contrast, all polyphenols showed pronounced antileishmanial activities (EC(50) < 0.4 - 12.5 versus 7.9 microg/ml for Pentostam) against intracellular amastigotes of L. donovani residing within RAW cells. Noteworthy, most compounds exhibited low cytotoxicity against the murine host cells (EC(50) >25 microg/ml). Furthermore, some ellagitannins and the majority of dehydroellagitannins induced potent interferon-like activities as reflected by inhibition of the cytopathic effect of encephalomyocarditis virus on fibroblast L929 cells. This is the first report on hydrolyzable tannins as a new class of natural products with leishmanicidal activity including their potential for inducing the release of NO, TNF and IFN-like activity in macrophage-like RAW cells.

Animals↗
PubMed2001

Marked potentiation of activity of beta-lactams against methicillin-resistant Staphylococcus aureus by corilagin.

We found that an extract of Arctostaphylos uva-ursi markedly reduced the MICs of beta-lactam antibiotics, such as oxacillin and cefmetazole, against methicillin-resistant Staphylococcus aureus. We isolated the effective compound and identified it as corilagin. Corilagin reduced the MICs of various beta-lactams by 100- to 2,000-fold but not the MICs of other antimicrobial agents tested. The effect of corilagin and oxacillin was synergistic. Corilagin showed a bactericidal action when added to the growth medium in combination with oxacillin.

Anti-Bacterial Agents↗
PubMed2001

Proanthocyanidins and related compounds: antileishmanial activity and modulatory effects on nitric oxide and tumor necrosis factor-alpha-release in the murine macrophage-like cell line RAW 264.7.

A series of 17 proanthocyanidins and structurally related compounds was tested for activity against Leishmania donovani amastigotes and promastigotes in vitro. Most of the polyphenols significantly inhibited the intracellular survival of L. donovani amastigotes (EC50 0.8-10.6 nM) when compared with the antileishmanial drug Pentostam (EC50 10.6 nM), but all were inactive against the extracellular form (EC50 7.8 to >86 nM). Noteworthy is that all compounds exhibited only moderate or no cytotoxicity against the murine host cells (EC50 7.8 to >56 nM; >25 microg/ml). These polyphenols were further evaluated for immunomodulatory effects on macrophage functions, including release of nitric oxide (NO), tumor necrosis factor-alpha (TNF) and interferon (IFN)-like properties using several functional assays. The results showed that all compounds induced murine RAW 264.7 cells only moderately to release NO (7-26 microM) relative to the reference stimulus IFN-gamma/LPS (119 microM). The TNF-inducing potential of the polyphenols producing 50% lysis in murine L929 cells ranged from absent to 138 U/ml at the host cell subtoxic concentration of 50 microg/ml. The highest TNF-inducing activity was associated with those flavan-3-ols with galloyl groups (98-127 U/ml). For proanthocyanidins, it appeared that an increase in the flavanyl chain length did not enhance the induction of TNF-release (32-86 U/ml and below detection limits for oligomers and polymers, respectively). With interferon-like activities, phylloflavan and a prodelphinidin polymer showed appreciable cytoprotective effects, as reflected by the inhibition of the cytopathic effect of encephalomyocarditis virus on L929 fibroblast cells (38 and 36 U/ml, respectively). All remaining compounds displayed only negligible or moderate protective effects at subtoxic concentrations up to 25 microg/ml (<5 to 12 U/ml). These results indicate that proanthocyanidins and related compounds have favorable antileishmanial activity in vitro and might be considered as beneficial immunological response modifiers provided there are no bioavailability problems.

Adjuvants, Immunologic↗