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T Nishizaki

Publications and source records attributed to T Nishizaki.

At least 19 recordsLinked to original sources
PubMed2006

Laparoscopy-assisted right hepatic lobectomy using a wall-lifting procedure.

This article describes a new technique for performing a laparoscopy-assisted right hepatic lobectomy using a hanger wall-lifting procedure. The patient is placed in the left semi-lateral position. A cholecystectomy and hemi-hepatic vascular inflow control are then performed through a midline incision, through which the resected liver can be removed. Next, the right lower chest and right upper abdominal wall are lifted by two wires vertical to the abdominal wall. Two ports, a 5-mm port in right lateral abdomen for forceps and a 12-mm port just right of the umbilicus for the laparoscope, are inserted. The obtained view of the operative field in the right upper abdominal cavity is thus excellent. The laparoscopy-assisted mobilization of the right hepatic lobe is done with the assistance of a hand inserted through the midline incision, including a dissection of the hepato-renal ligament, the right triangular ligament, and the right coronary ligament. A parenchymal dissection is then performed using the Cavitron Ultrasonic Surgical Aspirator (CUSA) and the resected specimen is passed through the midline incision without any morcellation of the liver. This procedure can minimize the length of the wound, while avoiding the lethal complications associated with pneumoperitoneum.

Hepatectomy↗
PubMed2006

A loss of c-kit expression is associated with an advanced stage and poor prognosis in breast cancer.

To evaluate the c-kit expression in breast cancer, 217 invasive ductal carcinomas of the breast were immunohistochemically stained for c-kit protein. The c-kit expression was positive in 59 (27%) of 217 tumours, while the c-kit expression was negative in 158 (73%) of 217 tumours. There was a significant correlation between a negative expression of the c-kit protein and lymph node metastasis (P < 0.0001), and the incidence of a negative expression of the c-kit protein increased as the number of the metastatic lymph nodes increased (P = 0.0003). The c-kit expression did not significantly correlate with the tumour size, nuclear grade, oestrogen receptor status, MIB-1 counts and p53 protein expression. A univariate analysis indicated the patients with the negative c-kit expression to have a worse disease-free survival (DFS) than those with the positive c-kit expression (P = 0.0041), while a multivariate analysis determined lymph node metastases and the MIB-1 counts to be independently significant factors for DFS. In conclusion, a loss of the c-kit expression was found in about three-fourth of invasive ductal carcinoma of the breast and was associated with lymph node metastases. The prognostic implications of the c-kit expression seem to be due to fact that a loss of the c-kit expression is associated with an advanced stage of breast cancer.

Biomarkers, Tumor↗
PubMed2006

Weak magnetic order in the normal state of the high-Tc superconductor La2-xSrxCuO4.

We report magnetization measurements in the normal state of the high transition temperature (high-Tc) superconductor La2-xSrxCuO4. A magnetic order in the form of hysteresis in the low-field magnetization is observed at temperatures well above Tc. The doping (x) dependence of the onset and strength of this order follows Tc(x) and falls within the pseudogap regime.

Journal Article↗
PubMed2006

The role of cyberknife radiosurgery/radiotherapy for brain metastases of multiple or large-size tumors.

OBJECTIVE: Focused, highly targeted radiosurgery and fractionated radiotherapy using the Cyberknife are useful treatments for multiple or large metastases. Here we present our results of Cyberknife radiosurgery for 71 patients with 148 metastatic brain lesions. METHODS: There were 32 women and 39 men with a median age of 63 (range: 30-88) years. Radiographic follow-up was available for 60 patients with 104 lesions. The mean and median initial volumes of the tumor per lesion were 6.6 and 2.9 cm(3) (range: 0.1-53.2 cm(3)), respectively, at the time of the initial Cyberknife treatment. Forty patients (56%) had a single lesion, and 31 (44%) had multiple lesions (range: 2-7) at initial treatment. The number of fractions ranged from 1 to 3, and forty (27%) of 148 lesions were treated by a fractionated course of Cyberknife therapy. The mean marginal dose was 20.2 Gy (range 7.8-30.1 Gy, median: 20.7 Gy). RESULTS: At 44 weeks of median follow-up, there were no permanent symptoms resulting from radiation necrosis. Overall 6-month and 1-year survival rates were 74% and 47%, respectively, and the median survival time was 56 weeks. The Karnofsky performance score and extracranial metastasis were significant prognostic factors at 6 months and 1 year, respectively, in both univariate and multivariate analyses. Age or multiple metastases did not influence prognosis at 6 months and 1 year. Local control was achieved in 83% (86 lesions). After additional radiosurgical or surgical salvage, no patient died as a result of intracranial disease. Twenty-five patients developed 92 new metastases (range 1-13) outside of the treated lesions with 22.4 weeks of median follow-up. Among them, 21 patients (84 lesions) were treated by salvage Cyberknife. CONCLUSION: Despite the inclusion of an unfavorable group of patients with large tumors, our results for survival and tumor control rates are comparable to those of published series. The Cyberknife provides the advantage of allowing for fractionated treatment to multiple or large-size tumors.

Adult↗
PubMed2005

The linoleic acid derivative FR236924 facilitates hippocampal synaptic transmission by enhancing activity of presynaptic alpha7 acetylcholine receptors on the glutamatergic terminals.

The present study aimed at understanding the effect of FR236924, a newly synthesized linoleic acid derivative with cyclopropane rings instead of cis-double bonds, on hippocampal synaptic transmission in both the in vitro and in vivo systems. FR236924 increased the rate of alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor-mediated miniature excitatory postsynaptic currents, without affecting the amplitude, triggered by nicotine in CA1 pyramidal neurons of rat hippocampal slices, that is inhibited by GF109203X, a selective protein kinase C (PKC) inhibitor or alpha-bungarotoxin, an inhibitor of alpha7 acetylcholine (ACh) receptors. FR236924 stimulated glutamate release from rat hippocampal slices and in the hippocampus of freely behaving rats, and the effect was also inhibited by GF109203X or alpha-bungarotoxin. FR236924 induced a transient huge potentiation followed by a long-lasting potentiation in the slope of field excitatory postsynaptic potentials recorded from the CA1 region of rat hippocampal slices, and the latter effect was blocked by GF109203X or alpha-bungarotoxin. Likewise, the compound persistently facilitated hippocampal synaptic transmission in the CA1 region of the intact rat hippocampus. It is concluded from these results that FR236924 stimulates glutamate release by functionally targeting presynaptic alpha7 ACh receptors on the glutamatergic terminals under the influence of PKC, responsible for the facilitatory action on hippocampal synaptic transmission. This may provide evidence for a link between cis-unsaturated free fatty acids and presynaptic alpha7 ACh receptors in hippocampal synaptic plasticity.

Alkanes↗
PubMed2004

Preferential expression of the vasoactive intestinal peptide (VIP) receptor VPAC1 in human cord blood-derived CD34+CD38- cells: possible role of VIP as a growth-promoting factor for hematopoietic stem/progenitor cells.

Primitive hematopoietic progenitor cells such as severe combined immunodeficiency- repopulating cells and long-term culture-initiating cells are enriched in CD34+CD38- cells derived from various stem cell sources. In this study, to elucidate the features of such primitive cells at the molecular level, we tried to isolate genes that were preferentially expressed in umbilical cord blood (CB)-derived CD34+CD38- cells by subtractive hybridization. The gene for VPAC1 receptor, a receptor for the neuropeptide vasoactive intestinal peptide (VIP), was thereby isolated and it was shown that this gene was expressed in both CD34+CD38- and CD34+CD38+ CB cells and that the expression levels were higher in CD34+CD38- CB cells. Next, we assessed the effects of VIP on the proliferation of CD34+ CB cells using in vitro culture systems. In serum-free single-cell suspension culture, VIP enhanced clonal growth of CD34+ CB cells in synergy with FLT3 ligand (FL), stem cell factor (SCF), and thrombopoietin (TPO). In serum-free clonogenic assays, VIP promoted myeloid (colony-forming unit-granulocyte/macrophage (CFU-GM)) and mixed (CFU-Mix) colony formations. Furthermore, in Dexter-type long-term cultures, VIP increased colony-forming cells at week 5 of culture. These results suggest that VIP functions as a growth-promoting factor of CB-derived hematopoetic progenitor cells.

ADP-ribosyl Cyclase↗
PubMed2004

CyberKnife radiosurgery for vestibular schwannoma.

OBJECTIVE: The CyberKnife is newly developed equipment for radiosurgery and fractionated radiosurgery. The authors report on their experience using the CyberKnife in 38 patients with vestibular schwannoma who were treated between 1998 to 2002. METHODS: During this period, 38 patients with vestibular schwannoma were treated using CyberKnife fractionated radiosurgery. Before undergoing fractionated radiosurgery, 14 patients had Gardner Robertson classes I or II hearing (the serviceable hearing group), and 24 patients had classes III to V hearing (the non-serviceable hearing group). The treatment volumes of these two groups were 0.5 to 24.0 cm (3) (mean 4.7 cm (3)), and 0.5 to 41.6 cm (3) (mean 8.2 cm (3)). Target irradiation was administered in 1 - 3 fractions (mean 2.5 fractions). The total marginal radiation doses were 15.0 to 20.5 Gy (mean 17.0 Gy), and 11.9 to 20.1 Gy (mean 16.9 Gy), respectively. RESULTS: After a mean follow-up period of 31.9 months (range 12 to 59 months, median 27 months), 94 % of the tumors were controlled. Only one patient in the group with non-serviceable hearing underwent additional surgical resection for a presumed increase in tumor size. The hearing preservation rate was 93 %. Facial weakness did not develop in any of the patients in the serviceable hearing group. New trigeminal symptoms did not develop in any patients in either group. CONCLUSION: Although a longer and more extensive follow-up is needed, CyberKnife fractionated radiosurgery is considered to be safe and effective, even in patients with large tumors.

Adolescent↗
PubMed2003

Image-guided transsphenoidal surgery for pituitary lesions using Mehrkoordinaten Manipulator (MKM) navigation system.

Twenty-five patients with pituitary lesions were operated on by image-guided transsphenoidal surgery (TSS) using the Mehrkoordinaten Manipulator (MKM) navigation system. The cases included 21 cases of pituitary adenomas, 2 cases of craniopharyngioma and 2 cases of Rathke's cleft cyst. All operations were performed through the sublabial approach under an operative microscope. In some cases, an endoscope was used for the observation of the residual tumor and surrounding structures. The tumors and surrounding important structures such as the internal carotid arteries, the basilar artery, and the optic nerves were precisely localized, and mechanical error was less than 2 mm in almost all cases. In 3 early cases of pituitary adenoma, the patient's head was moved slightly during the insertion of the nasal speculum; in these cases, the resulting error was more than 2 mm. In evaluating the procedures, we determined that the most useful benefit of the MKM system compared with other systems is that the navigation information is not only displayed on the monitor, but also presented in the operative field under the microscope. Therefore, the surgeon can obtain the navigation information without removing his eyes from the operative field under the microscope. The most important drawback to the system is its bulky size.

Adenoma↗
PubMed2002

A new neuromodulatory pathway with a glial contribution mediated via A(2a) adenosine receptors.

A low concentration (10 nM) of adenosine potentiated hippocampal neuronal activity via A(2a) adenosine receptors without affecting presynaptic glutamate release or postsynaptic glutamatergic conductance. Adenosine inhibited glutamate uptake through the glial glutamate transporter, GLT-1, via A(2a) adenosine receptors. In addition, adenosine stimulated GLT-1-independent glutamate release from astrocytes, possibly in response to a rise in intracellular Ca(2+), via A(2a) adenosine receptors involving PKA activation. Those adenosine actions could lead to an increase in synaptic glutamate concentrations responsible for the potentiation of hippocampal neuronal activity. The results of the present study thus represent a novel neuromodulatory pathway with a glial contribution, bearing both inhibition of GLT-1 function and stimulation of glial glutamate release, as mediated via A(2a) adenosine receptors.

Adenosine↗
PubMed2001

Beneficial effects of 3-dimensional visualization on hepatic vein reconstruction in living donor liver transplantation using right lobe graft.

BACKGROUND: Recently, virtual operation planning and navigation systems have been introduced in the field of neurosurgery and orthopedic surgery. We report here the beneficial effects of 3-dimensional (3D) visualization on hepatic venous reconstruction in living donor liver transplantation (LDLT) using right lobe graft. METHODS: 3D-image reconstruction of the liver was rendered with 3-mm slices of helical computed tomography (CT) data using zioM900 (Zio Software Inc., Tokyo, Japan). To understand the anatomy of the donor's vessels and design an operation plan, a picture of the vessels in and around the liver was reconstructed. RESULTS: The 3D image demonstrated two short hepatic veins next to the inferior right hepatic vein (IRHV) as well as a large IRHV. The 3D image showed a more precise diameter of the right hepatic vein (RHV) and the IRHV and a more accurate distance between the two hepatic veins than did images measured by 2-dimensional CT. This preoperative information allowed the donor surgeon to dissect the inferior vena cava (IVC) and hepatic veins with reduced blood loss because of reduced risk of injury to the blood vessels. The 3D image revealed that both the RHV and the IRHV branched off at the same angle from the cylindrical IVC. Preoperative planning based on this information secured smooth anastomosis. CONCLUSIONS: 3D visualization is useful for hepatic venous reconstruction of the recipient as well as for donor surgery in LDLT using right lobe graft.

Female↗
PubMed2001

Role of glial glutamate transporters in the facilitatory action of FK960 on hippocampal neurotransmission.

We found previously that N-(4-acetyl-1-piperazinyl)-p-fluorobenzamide monohydrate (FK960) facilitated hippocampal neurotransmission in the dentate gyrus of rat hippocampal slices. The present study was conducted to understand the mechanism underlying the facilitatory action of FK960. The facilitation was inhibited by H-89, an inhibitor of cAMP-dependent protein kinase (PKA), but it was not affected by cycloheximide, a protein synthesis blocker. In cultured rat hippocampal neurons, the drug had no effect on either spontaneous miniature excitatory postsynaptic currents or whole-cell membrane currents evoked by glutamate, kainate, or NMDA, suggesting that the facilitatory action of FK960 is not caused by increasing presynaptic transmitter release or excitatory postsynaptic conductances. FK960 inhibited responses of the glial glutamate transporter, GLT-1, expressed in Xenopus oocytes, and a similar effect was found with cultured rat astrocytes. The FK960 action was inhibited in the presence of H-89. The results of the present study thus suggest that FK960 facilitates hippocampal neurotransmission by inhibiting GLT-1 glial glutamate reuptake via a PKA pathway, thereby increasing synaptic glutamate concentrations.

Amino Acid Transport System X-AG↗
PubMed2001

The protective action of nefiracetam against electrophysiological and metabolic damage in the hippocampus after deprivation of glucose and oxygen.

The present study examined the effect of nefiracetam on ischemic brain damage by monitoring population spikes (PSs) in the dentate gyrus of guinea pig hippocampal slices; assaying high-energy phosphates (ATP and CrP) in guinea pig hippocampal slices; and monitoring whole-cell membrane-currents and intracellular Ca(2+) levels in cultured hippocampal neurons. Twenty-minute ischemic insult to slices, i.e., deprivation of glucose and oxygen from artificial cerebrospinal fluid, abolished PSs. As compared with only 35% recovery of the PS amplitude for control, PS amplitude reversed to 65% of basal levels 40 min after returning normal conditions by treatment with nefiracetam (0.01 microM). Ischemic insult reduced the levels of adenosine triphosphate (ATP) and creatine phosphate (CrP) in slices, and when returned to normal conditions, recovering to 70 and 85% of basal values, respectively, 30 min after returning normal conditions. Nefiracetam (0.01 microM) facilitated the recovery of ATP and CrP, reaching 110 and 140% of basal values, respectively. Nefiracetam inhibited N-methyl-D-aspartate (NMDA)-evoked currents to 35% of basal amplitudes. Likewise, nefiracetam (0.01 microM) inhibited intracellular Ca(2+) rise through NMDA receptor channels to 30% of basal levels. The results of the present study, thus, suggest that nefiracetam has the potential to protect against ischemic brain damage, possibly in part by preventing from accumulation of intracellular calcium through NMDA receptor channels.

Adenosine Diphosphate↗
PubMed2001

Selective cholinergic denervation inhibits expression of long-term potentiation in the adult but not infant rat hippocampus.

The present study assessed the role of the cholinergic systems on the expression of perforant path long-term potentiation (LTP) in rat hippocampal slices from the infant and adult brain. To denervate the cholinergic systems, 192 IgG--saporin was injected into the lateral ventricle of the infant (2-weeks-old) and adult (6-weeks-old) rat brain. There, choline acetyltransferase-immunoreactive fibers were barely detectable 2 weeks and 2 months after injection for both the groups. For the infant rats, perforant path LTP was not affected by selective cholinergic denervation; the probability of LTP development was 0.83 (five out of six slices) and 0.78 (seven out of nine slices) at 2 weeks and 2 months later in 192 IgG--saporin-treated slices, as compared with 0.83 at each period in control saline-treated slices. In contrast, the expression of the LTP was blocked by selective cholinergic denervation for the adult rats; the probability of LTP development was 0 (zero out of 10 slices) and 0.38 (three out of eight slices) at 2 weeks and 2 months later in 192 IgG--saporin-treated slices, as compared with 0.8 (eight out of 10 slices) and 0.83 (five out of six slices) at each period in control saline-treated slices. The results of the present study thus suggest that the cholinergic systems play a crucial role in the expression of LTP in the adult brain and that the denervated systems in the infant brain could be compensated by the sprouting of non-cholinergic fibers.

Age Factors↗
PubMed2001

A long-lasting facilitation of hippocampal neurotransmission via a phospholipase A2 signaling pathway.

Phospholipase A2, which is linked to a protein kinase C pathway, hydrolyzes phosphatidylcholine into cis-unsaturated free fatty acids and lysophosphatidylcholine (lysoPC). The present study investigated the effect of the free fatty acids, such as arachidonic, oleic, linoleic, and linolenic acid, and lysoPC on neurotransmission by monitoring population spikes (PSs) from the granular cell layer of rat hippocampal slices. All the free fatty acids and lysoPC examined here gradually increased PS amplitude to a different extent, the effect being evident 60 min after treatment. No significant synergistic enhancement in the PS amplitude was not induced by arachidonic acid following oleic acid, linoleic acid or lysoPC. The results of the present study, thus, demonstrate that phospholipase A2-linked free fatty acids and lysoPC are employed in the sustained facilitation of hippocampal neurotransmission, suggesting a significant role of a phospholipase A2 signaling pathway in the neuroplasticity.

Animals↗
PubMed2001

NMDA-responsible, APV-insensitive receptor in cultured human astrocytes.

The present study was conducted to assess N-methyl-D-aspartate (NMDA)-responsible receptors in cultured human astrocytes by monitoring whole-cell membrane currents. NMDA generated currents, that are potentiated by glycine and blocked by Mg2+, with the current/voltage relation showing a reversal potential of +/- 0 mV. The currents were not inhibited by either the selective NMDA receptor antagonist, D-2-amino-5-phosphonovaleric acid (APV), or the non-selective ionotropic glutamate receptor antagonist, kynurenic acid. The currents were inhibited only by 19% in Ca2+-free extracellular solution. Furthermore, GDPbetaS, a broad G-protein inhibitor, inhibited NMDA-induced currents to 82% of original levels. The results of the present study thus suggest that an NMDA-responsible, APV-insensitive receptor with low Ca2+ permeability, distinct from the neuronal NMDA receptors, is expressed in human astrocytes and that the receptor is regulated in part by an unknown G-protein-linked receptor.

Astrocytes↗
PubMed2001

Adenosine enhances glial glutamate efflux via A2a adenosine receptors.

The present study investigated the effect of adenosine on glial glutamate efflux. Adenosine (from 1 nM to 100 microM) enhanced the release from cultured rat glial cells in a bell-shaped dose-responsive manner for the hippocampus and in a dose-dependent manner for the superior colliculus, and a similar increase was obtained with the A2a adenosine receptor agonist, 2-p-(2-carboxyethyl) phenethylamino-5'-N-ethylcarboxamidoadenosine hydrochloride (CGS21680), but not with the A1 adenosine receptor agonist, N6-cyclohexyladenosine (CHA). Adenosine and CGS21680 also enhanced glutamate efflux from Xenopus oocytes injected with the poly (A)+ mRNAs derived from cultured glial cells for the hippocampus and the superior colliculus together with and without the A2a adenosine receptor mRNA, but instead such increase was not found in oocytes expressing A2a adenosine receptors alone. The results of the present study thus suggest that adenosine enhances glutamate efflux from glial cells via A2a adenosine receptors, and this may represent a mechanism underlying the facilitatory action of adenosine on hippocampal and superior colliculus neurotransmissions.

Adenosine↗
PubMed2001

Identification of recurrent chromosomal rearrangements and the unique relationship between low-level amplification and translocation in glioblastoma.

To elucidate the structural abnormalities and the relationship between chromosome structural disorders and DNA copy number aberrations in tumor cells, we applied the techniques of spectral karyotyping (SKY), comparative genomic hybridization (CGH), and fluorescence in situ hybridization (FISH), using yeast artificial chromosome (YAC) probes for nine human glioblastoma cell lines. One striking finding was that independently derived cell lines had the same recurrent marker chromosomes. Seven recurrent chromosomes were detected by these cytogenetic methods. In particular, cell lines U251, SNB-19, and U373-MG showed very similar karyotypes. It is also interesting that regions of DNA amplification were found translocated and/or inserted at a high rate (91.7%). In all, there were 12 amplified loci in five of the nine cell lines. These amplified chromosomal bands were scattered on the chromosomes, including the normal chromosome, with one exception (7q32-qter in U373-MG). FISH with YAC clones mapping to these chromosomal regions as DNA probes often showed DNA probe signals not only at original chromosomal sites but also in translocated or inserted segments. This form of DNA amplification was characterized by low-level increases (four- to 10-fold) and by translocation or insertion of the relevant chromosomal locus. These studies shed light on typical derivative chromosomes and the relationship between DNA amplification and chromosomal translocation in glioblastoma.

Chromosome Aberrations↗