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Biomedical subjects

S Takamori

Publications and source records attributed to S Takamori.

At least 19 recordsLinked to original sources
PubMed2004

An essential role for vesicular glutamate transporter 1 (VGLUT1) in postnatal development and control of quantal size.

Quantal neurotransmitter release at excitatory synapses depends on glutamate import into synaptic vesicles by vesicular glutamate transporters (VGLUTs). Of the three known transporters, VGLUT1 and VGLUT2 are expressed prominently in the adult brain, but during the first two weeks of postnatal development, VGLUT2 expression predominates. Targeted deletion of VGLUT1 in mice causes lethality in the third postnatal week. Glutamatergic neurotransmission is drastically reduced in neurons from VGLUT1-deficient mice, with a specific reduction in quantal size. The remaining activity correlates with the expression of VGLUT2. This reduction in glutamatergic neurotransmission can be rescued and enhanced with overexpression of VGLUT1. These results show that the expression level of VGLUTs determines the amount of glutamate that is loaded into vesicles and released and thereby regulates the efficacy of neurotransmission.

Amino Acid Transport Systems, Acidic↗
PubMed2003

Role of alpha-synuclein in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced parkinsonism in mice.

In humans, mutations in the alpha-synuclein gene or exposure to the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) produce Parkinson's disease with loss of dopaminergic neurons and depletion of nigrostriatal dopamine. alpha-Synuclein is a vertebrate-specific component of presynaptic nerve terminals that may function in modulating synaptic transmission. To test whether MPTP toxicity involves alpha-synuclein, we generated alpha-synuclein-deficient mice by homologous recombination, and analyzed the effect of deleting alpha-synuclein on MPTP toxicity using these knockout mice. In addition, we examined commercially available mice that contain a spontaneous loss of the alpha-synuclein gene. As described previously, deletion of alpha-synuclein had no significant effects on brain structure or composition. In particular, the levels of synaptic proteins were not altered, and the concentrations of dopamine, dopamine metabolites, and dopaminergic proteins were unchanged. Upon acute MPTP challenge, alpha-synuclein knockout mice were partly protected from chronic depletion of nigrostriatal dopamine when compared with littermates of the same genetic background, whereas mice carrying the spontaneous deletion of the alpha-synuclein gene exhibited no protection. Furthermore, alpha-synuclein knockout mice but not the mice with the alpha-synuclein gene deletion were slightly more sensitive to methamphetamine than littermate control mice. These results demonstrate that alpha-synuclein is not obligatorily coupled to MPTP sensitivity, but can influence MPTP toxicity on some genetic backgrounds, and illustrate the need for extensive controls in studies aimed at describing the effects of mouse knockouts on MPTP sensitivity.

3,4-Dihydroxyphenylacetic Acid↗
PubMed2001

Identification of differentiation-associated brain-specific phosphate transporter as a second vesicular glutamate transporter (VGLUT2).

Glutamate is the major excitatory neurotransmitter in mammalian CNS. In the presynaptic nerve terminal, glutamate is stored in synaptic vesicles and released by exocytosis. Previously, it has been shown that a transport protein originally identified as a brain-specific Na(+)-dependent inorganic phosphate transporter I (BNPI) functions as vesicular glutamate transporter and thus has been renamed VGLUT1. Recently, a protein highly homologous to VGLUT1, "differentiation-associated BNPI" (DNPI), has been discovered. Northern blot and in situ hybridization analyses indicate that DNPI mRNA is expressed in some brain regions in which VGLUT1 mRNA is not expressed. We now show that DNPI functions as vesicular glutamate transporter with properties very similar to VGLUT1 and propose to rename the protein VGLUT2. VGLUT2 is highly enriched in synaptic vesicles. Furthermore, VGLUT2 resides on a vesicle population that is distinct from vesicles containing the vesicular GABA transporter or VGLUT1, showing that the expression of VGLUT1 and VGLUT2 do not overlap. When VGLUT2 was expressed in BON cells, membrane fractions displayed ATP-dependent, carbonyl cyanide p-trifluoromethoxyphenylhydrazone-sensitive glutamate uptake. Overexpression of VGLUT2 in cultured autaptic GABAergic neurons yielded postsynaptic currents that were insensitive to the GABA(A) receptor antagonist bicuculline but blocked by the AMPA-receptor antagonist 2,3-dihydroxy-6-nitro-7-sulfonyl-benzo[F]quinoxaline. Thus, expression of VGLUT2 suffices to cause GABAergic neurons to release glutamate in addition to GABA in a manner very similar to that reported previously for VGLUT1.

Animals↗
PubMed2001

Successful treatment of sternal osteomyelitis after pneumonectomy using a pedicled omental flap.

We report here the case of a 64-year-old man with sternal osteomyelitis after pneumonectomy through a median sternotomy who was successfully treated using a pedicled omental flap. This is the first report in the literature to describe sternal osteomyelitis and mediastinitis after pneumonectomy. In this case, the visceral pleura of the remnant right lung was located just under the infected sternum. Careful management is recommended because empyema pleurae can be a fatal complication.

Carcinoma, Squamous Cell↗
PubMed2001

Double cancers in the common bile duct: molecular genetic findings with an analysis of LOH.

We report a 69-year-old man with double cancers in the common bile duct. One cancer was located between the superior and middle parts of the bile duct, while the other cancer was in the inferior part of the bile duct. Pylorus-preserving pancreatoduodenectomy was performed. There was no communication between the two cancers in either the mucosal layer or the subepithelial layer. On pathological examination, the upper cancer was diagnosed as poorly differentiated adenocarcinoma, while the lower one was found to be moderately differentiated adenocarcinoma. We analyzed loss of heterozygosity (LOH), using microsatellite markers on five chromosomal arms, in both the upper and the lower cancers. Both cancers showed common regions of LOH at 5q, 6q, 9p, 17p, and 18q, whereas the upper cancer showed one additional region of LOH at 8p, thus suggesting progression, due to the acquisition of the additional LOH, in the upper cancer. No LOH was observed in the region between the two cancers. The presence of one additional LOH in the upper cancer suggests that the upper cancer was a metastasis of the lower one.

Adenocarcinoma↗
PubMed2001

Disruption of ClC-3, a chloride channel expressed on synaptic vesicles, leads to a loss of the hippocampus.

Several plasma membrane chloride channels are well characterized, but much less is known about the molecular identity and function of intracellular Cl- channels. ClC-3 is thought to mediate swelling-activated plasma membrane currents, but we now show that this broadly expressed chloride channel is present in endosomal compartments and synaptic vesicles of neurons. While swelling-activated currents are unchanged in mice with disrupted ClC-3, acidification of synaptic vesicles is impaired and there is severe postnatal degeneration of the retina and the hippocampus. Electrophysiological analysis of juvenile hippocampal slices revealed no major functional abnormalities despite slightly increased amplitudes of miniature excitatory postsynaptic currents. Mice almost lacking the hippocampus survive and show several behavioral abnormalities but are still able to acquire motor skills.

Acids↗
PubMed2001

Clinical investigation of endothelin-1 and nitric oxide in patients with portal hypertension focusing on plasma levels and immunohistological staining of liver tissues.

Plasma concentrations of endothelin-1 (ET-1) and nitrite/nitrate of patients with portal hypertension were measured. Sixteen patients with liver cirrhosis (the LC group) and 14 patients with idiopathic portal hypertension (the IPH group) and 12 healthy subjects (normal controls) were included in this study. The peripheral venous plasma concentration of ET-1 was significantly higher in the LC group (6.69+/-2.44 pg/ml) than in the IPH group (3.07+/-0.84 pg/ml) and normal controls (1.79+/-0.36 pg/ml), while the value in the IPH group was also significantly higher than that in normal controls. The peripheral venous plasma concentration of nitrite/nitrate was significantly higher in the LC group (67.7+/-38.9 &mgr;Mol/l) than in the IPH group (32.3+/-24.4 &mgr;Mol/l) and normal controls (26.1+/-9.8 &mgr;Mol/l). Hepatic venous plasma concentrations of ET-1 and nitrite/nitrate were measured in 8 patients from the LC group and 10 patients from the IPH group. The plasma concentration of ET-1 in the hepatic vein was significantly higher than that in the peripheral vein in both the LC and the IPH groups. The plasma concentration of nitrite/nitrate in the hepatic vein was significantly higher than that in the peripheral vein in the LC group. We also investigated the localization of ET-1, endothelin receptor (ET receptor) and nitric oxide synthase (NOS) in the liver tissue of LC patients (n=10), IPH patients (n=10) and normal controls (n=10). The expressions of ET-1, ET A receptors, ET B receptors, and inducive NOS (iNOS) were detected in patients with LC, and the labeling index (LI) was significantly higher than that in patients with IPH and normal controls. The expressions of ET-1, ET A receptors, and ET B receptors were found in patients with IPH, and the LI was significantly higher than that in normal controls. The expression of endothelial NOS (eNOS) was scarce in both LC and IPH patients. From these results, overproduction of ET-1 in the liver was regarded as one of the causes of the high plasma concentration of ET-1 in patients with LC and IPH. One of the causes of the high plasma concentration of nitrite/nitrate in LC was considered to be overproduction of nitric oxide (NO) in the liver. And we suggested that ET-1 is at a relatively higher density than NO in the hepatic sinusoid in LC and IPH.

Journal Article↗
PubMed2000

Identification of a vesicular glutamate transporter that defines a glutamatergic phenotype in neurons.

Glutamate is the major excitatory neurotransmitter in the mammalian central nervous system. Synaptic vesicles are loaded with neurotransmitter by means of specific vesicular transporters. Here we show that expression of BNPI, a vesicle-bound transporter associated with sodium-dependent phosphate transport, results in glutamate uptake by intracellular vesicles. Substrate specificity and energy dependence are very similar to glutamate uptake by synaptic vesicles. Stimulation of exocytosis--fusion of the vesicles with the cell membrane and release of their contents--resulted in quantal release of glutamate from BNPI-expressing cells. Furthermore, we expressed BNPI in neurons containing GABA (gamma-aminobutyric acid) and maintained them as cultures of single, isolated neurons that form synapses to themselves. After stimulation of these neurons, a component of the postsynaptic current is mediated by glutamate as it is blocked by a combination of the glutamate receptor antagonists, but is insensitive to a GABA(A) receptor antagonist. We conclude that BNPI functions as vesicular glutamate transporter and that expression of BNPI suffices to define a glutamatergic phenotype in neurons.

ATP-Binding Cassette Transporters↗
PubMed2000

Immunoisolation of GABA-specific synaptic vesicles defines a functionally distinct subset of synaptic vesicles.

Synaptic vesicles from mammalian brain are among the best characterized trafficking organelles. However, so far it has not been possible to characterize vesicle subpopulations that are specific for a given neurotransmitter. Taking advantage of the recent molecular characterization of vesicular neurotransmitter transporters, we have used an antibody specific for the vesicular GABA transporter (VGAT) to isolate GABA-specific synaptic vesicles. The isolated vesicles are of exceptional purity as judged by electron microscopy. Immunoblotting revealed that isolated vesicles contain most of the major synaptic vesicle proteins in addition to VGAT and are devoid of vesicular monoamine and acetylcholine transporters. The vesicles are 10-fold enriched in GABA uptake activity when compared with the starting vesicle fraction. Furthermore, glutamate uptake activity and glutamate-induced but not chloride-induced acidification are selectively lost during immunoisolation. We conclude that the population of GABA-containing synaptic vesicles is separable and distinct from vesicle populations transporting other neurotransmitters.

Adenosine Triphosphate↗
PubMed2000

Identification of a gene coding for a new squamous cell carcinoma antigen recognized by the CTL.

Peptide-based specific immunotherapy has resulted in tumor regression in some melanoma patients. However, tumor Ags and peptides for specific immunotherapy, except for treatment of melanomas, have not yet been well identified. In this study, we report a gene encoding a new squamous cell carcinoma (SCC) Ag recognized by cells of the HLA-A24-restricted and tumor-specific CTL line. This gene with 3958-bp length was transcribed from the chromosome 6q22 with six exons, and its mRNA was ubiquitously expressed in both SCCs and normal tissues, and partly expressed in adenocarcinomas. The deduced 958-aa sequence encoded by this gene showed no similarity to any known amino acid sequences. This gene product had a characteristic of an endoplasmic reticulum-resident protein. A 100-kDa protein was detected in the vast majority of SCCs from various tissues, in majority of renal cell carcinomas and brain tumors, and in about one-third of melanomas and adenocarcinomas from various organs other than the breast. In contrast, it was not expressed at all in any of the normal cells or tissues tested, including the testis and fetal liver. Three different peptides at positions 93-101, 161-169, and 899-907 of this Ag were recognized by this CTL line, and all of them induced HLA-A24-restricted and tumor-specific CTLs from PBMCs of SCC patients. Therefore, these peptides may be useful for peptide-based specific immunotherapy of HLA-A24+ patients with SCC in various organs, as well as for treatment of other cancer.

Amino Acid Sequence↗
PubMed2000

An experimental study of atrial natriuretic peptide levels and the effect of inhaled nitric oxide after pneumonectomy.

The aim of this study was to investigate the changes in atrial natriuretic peptide (ANP) levels and lung cyclic guanosine 3',5'-monophosphate (cGMP) concentrations caused by pneumonectomy (Pn), and the effect of inhaled nitric oxide (NO) after Pn in a canine model. The mean pulmonary arterial pressure (PAP) and plasma ANP levels were measured over 180 min in two groups of dogs, one subjected to 60 min of 5 ppm NO inhalation (Pn + NO group, n = 5) and one subjected to 180 min without NO inhalation (Pn group, n = 5). The ANP and cGMP levels in the lung were also measured before and after Pn. Both the PAP and ANP levels increased significantly. Inhaled NO rapidly reduced the PAP and plasma ANP to levels similar to those before Pn. The lung ANP level was significantly increased after Pn, but inhaled NO reduced it to a level similar to that before Pn. The lung cGMP level, which was significantly decreased after Pn, was significantly increased by NO inhalation. These results indicate that NO administration may be effective for preventing post-Pn pulmonary hypertension, although an elevation in ANP does not reduce the PAP.

Animals↗
PubMed2000

Significant changes in the serum levels of IL-6, h-HGF, and type IV collagen 7S during the perioperative period of a hepatectomy: relevance to SIRS.

We analyzed the changes in the serum levels of both interleukin-6 (IL-6), human hepatocyte growth factor (h-HGF), and type IV collagen 7S (7S) during the perioperative period of a hepatectomy and evaluated their relationship with systemic inflammatory response syndrome (SIRS). The study subjects consisted of 40 patients who underwent a hepatectomy. In 14 out of 40 patients, postoperative SIRS(+) was observed. Between the SIRS(+) and SIRS(-) cases, there were significant differences in the preoperative values of prothrombin time, hepaplastin test, cholinesterase, and indocyanine green retention at 15 min (P < 0.01). Compared with the SIRS(-) cases, the IL-6, h-HGF, and 7S of the SIRS(+) cases fluctuated in a higher range and remained significantly higher after postoperative day 1 (P < 0.05). Eight out of 14 SIRS(+) patients had postoperative complications. In the 8 SIRS(+) patients with postoperative complications and in the 4 patients in which the SIRS(+) state lasted 3 days or longer, the 7S levels were significantly higher during the perioperative period (P < 0.05). In the SIRS(+) cases, the postoperative levels of IL-6 and h-HGF, as well as pre- and postoperative levels of 7S, were elevated. We therefore consider these levels to be risk factors for complications during the perioperative period of a hepatectomy.

Collagen↗
PubMed2000

A preoperative alternating chemotherapy and radiotherapy program for patients with stage IIIA (N2) non-small cell lung cancer.

The objective of the present study was to evaluate the feasibility and toxicity of a preoperative alternating chemotherapy and radiotherapy program followed by surgery in stage IIIA non-small cell lung cancer (NSCLC). The tumor response, resection rate, tumor/lymph node downstaging, and survival were also evaluated. The positive predictive value (PPV) in the diagnosis of mediastinal lymph node metastasis was 81% using conventional magnetic resonance imaging (MRI) with short inversion-time inversion recovery (STIR) technique (STIR-MRI) on our criteria. Eligible patients had clinical N2 lesions (stage IIIA) and a World Health Organization (WHO) performance status of 0-2. The treatment program consisted of two courses of preoperative cisplatin, vindesine, and ifosfamide; alternating with radiotherapy, including two courses of 20 Gy radiation. Surgery was performed within 4 weeks after the treatment. Twenty-two patients with stage IIIA (N2) NSCLC (20 men and two women, age 35-71 years) were enrolled into the study. Hematologic and other toxicities were within an acceptable range. Surgery was not indicated for two patients because of distant metastasis; one patient with renal dysfunction and one with pancytopenia during this treatment underwent surgery subsequently. The clinical response rate was 50% (partial response in 11/22). Definitive surgery was indicated for 18 patients resulting in 17 patients with complete resection and one exploratory thoracotomy. A pathologic complete response of the primary tumor occurred in 41% of the patients (seven of 17; without residual tumor), whereas 58% (ten of 17) were pathologic N0. The median survival was 33 months with an actuarial 4-year survival rate of 33% in 17 patients with complete resection and 30 months with 28% 4-year survival rate in all entered patients. A randomized phase-III study using this approach for stage IIIA (clinical N-2 disease) is warranted.

Adult↗
PubMed2000

Synthesis and secretion of A-type natriuretic peptide in the auricular cardiocytes during pregnancy and lactation in mouse.

A-type (atrial) natriuretic peptide (ANP) levels in the auricular cardiocytes and plasma were examined by immunohistochemistry, electron microscopy, and radioimmunoassay in pregnant and lactating mice. Additionally, the cardiocyte ANP mRNA expression was measured by the polymerase chain reaction method. ANP-immunoreactivity (IR) and the number of ANP-granules in the cardiocytes on the 18th day of gestation were greater than those in virgin controls, but the plasma ANP concentration decreased on the 18th day of gestation. On the day of delivery, ANP-IR and the number of ANP-granules in the cardiocytes were decreased compared to those during the pregnancy and to those in virgin controls, and then began to increase continually until the 15th day of lactation. Plasma ANP concentration after delivery was significantly higher than that during pregnancy, and than that in virgin controls, and continued to increase until the 15th day of lactation. Cardiocyte ANP mRNA expression was highest on the day of delivery compared to that in all the other times. In conclusion, these results suggested that the circulating systems of ANP during pregnancy and lactation were regulated differentially.

Animals↗
PubMed2000

Bilateral pleural effusion following cervical abscess drainage: a case report.

Postoperative bilateral chylothorax after cervical surgery has been rarely reported, whereas unilateral chylothorax has been occasionally reported after thoracic surgery. Here, we report a rare case of bilateral pleural effusion that developed after cervical abscess drainage. On the second day after the drainage, the patient felt dyspnea, and bilateral pleural effusion was found on a chest X-ray. The effusion was thought to be chyle and was successfully treated with conservative management. Additionally here, we have suggested that non-traumatic chylothorax was caused by increasing intraluminal pressure occurring inside the thoracic duct after its ligation. Careful follow up of any respiratory symptoms and of chest X-rays is recommended after cervical intervention.

Abscess↗
PubMed2000

Thoracoscopic lung biopsy for diffuse infiltrative lung disease.

Thoracoscopic lung biopsy is becoming the procedure of first choice for the diagnosis of many localized and diffuse lung diseases. We have performed thoracoscopic lung biopsy for 17 patients with diffuse infiltrative lung disease, in Kurume University Hospital. There were 13 females and 4 males with a mean age of 48 years (range: 19-71 years). Thoracoscopic surgical biopsy was performed in the right lung in 12 and in the left lung in 5. Adequate lung tissue from each case was obtained for pathological examination. The mean surgical biopsy time was 49 min (range: 25-72 min) and bleeding was negligible. The mean duration for chest tube drainage was 2.6 days. No postoperative complication such as prolonged air leakage occurred. A specific diagnosis from the biopsy was achieved in 13 (76.4%) of the 17 cases. In only 6 (35.2%) of the 17 cases, the pathological diagnosis was the same as that from the thoracoscopic biopsy. In these 6 cases, the same diagnosis was obtained only in those with idiopathic interstitial pneumonitis or diffuse panbronchitis. Thoracoscopic lung biopsy was safe and useful for diagnosis for diffuse infiltrative lung disease.

Adolescent↗
PubMed2000

Changes in atrial natriuretic peptide concentration and expression of its receptors after pneumonectomy in the rat.

Atrial natriuretic peptide (ANP) is a cardiac hormone which affects endothelial cell function through a receptor-mediated process. Pneumonectomy is a common thoracic surgical procedure that can cause pulmonary oedema in the remaining lung. Few reports have investigated the aetiology of this complication. The aim of this study was to determine the changes in ANP concentration and expression of its receptors following pneumonectomy as a possible aetiology for postpneumonectomy pulmonary oedema (PPE). We compared plasma ANP concentrations, cGMP concentrations, and natriuretic peptide receptor (NPR)-A mRNA and NPR-C mRNA expression in rat lung 3 h after pneumonectomy (n=5) or a sham operation (n=5). The ANP concentrations in plasma and lung tissue in the pneumonectomy group were significantly higher than in the control group (749.5 versus 202.7 pg x ml(-1), P<0.01; 33.1 versus 6.8 ng x g(-1) wet tissue, P<0.01 respectively). The level of ANP mRNA expression in the pneumonectomy group was significantly higher than in the control group (1.44 versus 0.41 relative ANP mRNA expression, P<0.05). The concentration of cGMP and the level of NPR-A mRNA expression were not significantly different between the pneumonectomy and control groups. The level of NPR-C mRNA expression in the pneumonectomy group was significantly higher than in the control group (4.17 versus 2.19 relative NPR-C mRNA expression, P<0.01). These findings suggest that changes in pulmonary ANP and NPR-C expression may contribute to the development of PPE in the remaining lung in the acute phase following pneumonectomy.

Animals↗