Biomedical subjects

K Tsuzuki

Publications and source records attributed to K Tsuzuki.

At least 19 recordsLinked to original sources

PubMed2002

Nephropathy of cyanotic congenital heart disease: clinical characteristics and effectiveness of an angiotensin-converting enzyme inhibitor.

AIMS: Nephropathy has long been recognized as a potential complication of cyanotic congenital heart disease (CCHD). There have been few large-scale studies or clinical reports on renal impairment in patients with CCHD; similarly, very few studies have examined the drug treatment of nephropathy in CCHD. We examined the clinical characteristics and effectiveness of enalapril, an angiotensin-converting enzyme inhibitor (ACE-I), in patients with CCHD complicated with significant proteinuria. MATERIALS AND METHODS: The clinical records of 37 patients with CCHD were evaluated; all were older than 10 years of age (median 19, range from 10 to 27) and had regular check-ups, including urinalysis. The treatment criteria for enalapril administration included significant proteinuria (urinary excretion > 1.0 g/24 h), stable cardiac condition and blood pressure within the normal range. RESULTS: Eleven patients (29.7%) had persistent proteinuria, 6 patients met the enalapril treatment criteria and 5 patients were treated for more than 12 months. Enalapril apparently reduced the urinary protein excretion in 4 of the 5 patients (80%). No consistent improvement of renal function, as evidenced in the glomerular filtration rate (GFR), renal plasma flow (RPF) or filtration fraction (FF) was found in these patients, but neither were any significant adverse effects noted. CONCLUSION: The incidence of nephropathy among patients with CCHD was about 30%, which was consistent with previous studies. It is worth considering the use of ACE-I when nephropathy accompanies CCHD.

Adolescent↗

PubMed2001

Glia-synapse interaction through Ca2+-permeable AMPA receptors in Bergmann glia.

Glial cells express a variety of neurotransmitter receptors. Notably, Bergmann glial cells in the cerebellum have Ca2+-permeable alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-type glutamate receptors (AMPARs) assembled without the GluR2 subunit. To elucidate the role of these Ca2+-permeable AMPARs, we converted them into Ca2+-impermeable receptors by adenoviral-mediated delivery of the GluR2 gene. This conversion retracted the glial processes ensheathing synapses on Purkinje cell dendritic spines and retarded the removal of synaptically released glutamate. Furthermore, it caused multiple innervation of Purkinje cells by the climbing fibers. Thus, the glial Ca2+-permeable AMPARs are indispensable for proper structural and functional relations between Bergmann glia and glutamatergic synapses.

Adenoviridae↗

PubMed2001

Extension of glial processes by activation of Ca2+-permeable AMPA receptor channels.

AMPA type-glutamate receptor channels (AMPARs) assembled without the GluR2 (GluR-B) subunit are characterized by high Ca2+ permeability, and are expressed abundantly in cerebellar Bergmann glial cells. Here we show that the morphology of cultured Bergmann glia-like fusiform cells derived from the rat cerebellum was changed by manipulating expression of Ca2+-permeable AMPARs using adenoviral vector-mediated gene transfer. Converting endogenous Ca2+-permeable AMPARs into Ca2+-impermeable channels by viral-mediated transfer of GluR2 gene induced retraction of glial processes. In contrast, overexpression of Ca2+-permeable AMPARs markedly elongated glial processes. The process extension was blocked by 2,3-Dihydroxy-6-nitro-7-sulfamoylbenzo(F)quinoxaline (NBQX), a specific antagonist of AMPAR. These results indicate that glutamate regulates the morphology of glial processes by activating Ca2+-permeable AMPARs.

Adenoviridae↗

PubMed2001

Triterpenoids from Adiantum caudatum.

Three triterpenoids, 8alpha-hydroxyfernan-25,7beta-olide, 3alpha-hydroxy-4alpha-methoxyfilicane and 19alpha-hydroxyferna-7,9(11)-diene were isolated from the fresh fronds of Adiantum caudatum. Their structures were elucidated by spectroscopic techniques. Thirteen known triterpenoids were also identified from this fern.

Ferns↗

PubMed2001

Sindbis viral-mediated expression of Ca2+-permeable AMPA receptors at hippocampal CA1 synapses and induction of NMDA receptor-independent long-term potentiation.

Gene manipulation in order to artificially express a particular gene in neurons in the central nervous system is a powerful tool for the analysis of brain function. Sindbis viral vectors have been developed to express high levels of foreign genes in postmitotic brain neurons with little transfection of glial cells. In this study, we expressed the gene encoding the unedited GluR2 (GluR-B) subunit of the AMPA-type glutamate receptor that forms inwardly rectifying and Ca2+-permeable channels, in rat CA1 hippocampal neurons in slice cultures using Sindbis viral vectors. The pyramidal cell layer of the CA1 region was injected with recombinant Sindbis viruses encoding both enhanced green fluorescent protein (GFP) and unedited GluR2. The GFP fluorescence from CA1 neurons could be detected as early as 6 h and reached a maximal level about 48 h postinfection. The inwardly rectifying and Ca2+-permeable AMPA receptors were expressed in most CA1 pyramidal cells expressing GFP. These AMPA receptors expressed by gene transfer were involved in fast excitatory neurotransmission elicited by electrical stimulation of the Schaffer collaterals in the stratum radiatum. Tetanic stimulation of Schaffer collaterals induced NMDA receptor-independent, long-term potentiation due to Ca2+ influx through the newly expressed AMPA receptors in the area densely stained with GFP. Thus, the combined use of Sindbis viral vectors with the GFP reporter allowed physiological examination of the roles of a specific gene product in synaptic function in well-characterized brain neurons.

Animals↗

PubMed2001

Absolute quantification of AMPA receptor subunit mRNAs in single hippocampal neurons.

alpha-Amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) receptor subunit (GluR1-4) mRNAs expressed by single neurons in rat hippocampal cultures were quantified by single-cell RT-PCR using an internal standard RNA after whole-cell patch-clamp recording. The internal standard RNA, derived from GluR2 with a single nucleotide substitution, was reverse-transcribed and PCR-amplified with the same efficiency as GluR1-4 mRNAs. The mean mRNA numbers harvested in vitro from pyramidal-like neurons on day 9 were 1150 +/- 324 molecules of GluR1, 1080 +/- 273 molecules of GluR2, 100 +/- 20 molecules of GluR3, and 50 +/- 10 molecules of GluR4 (mean +/- SEM, n = 12). In a non-pyramidal neuronal population that expresses AMPA receptors characterized by high Ca(2+) permeability, the numbers of GluR1, GluR3 and GluR4 mRNA molecules harvested per cell were 354 +/- 64, 25 +/- 17 and 168 +/- 36, respectively (n = 8). The GluR2 mRNA was not detected in this cell type. The calculated ratio of AMPAR mRNA molecules per total mRNA molecules was 1/240 in pyramidal-like neurons (1/500 for GluR2), being in the range obtained with total RNA from rat forebrain and cerebellum (1/170 and 1/380, respectively). Finally, our results indicated that the proportion of GluR1-4 mRNA located in neurites reached approximately 60% in pyramidal-like neurons. However, we found no evidence of preferential subcellular distribution of a given subunit.

Animals↗

PubMed2001

Significance of ACE genotypes and medical treatments in childhood focal glomerulosclerosis.

BACKGROUND: There is little information on the significance of angiotensin-converting enzyme (ACE) genotypes and medical treatments in children with primary focal segmental glomerulosclerosis (FSGS). METHODS: A multicenter retrospective study was performed on the role of ACE genotypes and medical treatments in 43 Japanese children with FSGS (20 males and 23 females), including 17 children who progressed to end-stage renal failure during the mean observation period of 6.9 +/- (SD) 5.0 years. RESULTS: The incidence of the D allele of the ACE gene was higher in the whole group of 43 children with FSGS and in a subgroup of 28 steroid-resistant FSGS children (p < 0.05) than in the 130 children of the healthy control group (0.48, 0.48, and 0.33, respectively). ACE genotypes did not affect renal survival in the whole FSGS group nor in the steroid-resistant subgroup. Among the 28 steroid-resistant children, treatment with ciclosporin was effective in delaying the development of end-stage renal failure (p = 0.044), independently of other treatment regimens. CONCLUSION: The present study of Japanese children with FSGS showed that the D allele of the ACE gene is associated with the development of FSGS, but not associated with the progression of FSGS which was greatly ameliorated with ciclosporin, irrespective of ACE genotypes.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed2001

Design and synthesis of N-terminal cyclic motilin partial peptides: a novel pure motilin antagonist.

Motilin antagonist was designed and synthesized on the basis of the structure-activity relationship analysis of porcine motilin that we reported recently. The drug design was performed on a specific concept to reduce a flexibility of peptide conformation of porcine motilin partial peptide by its cyclization. The cyclic peptide was synthesized using Boc (tert-butyloxycarbonyl) solid phase methodology, followed by cyclization using the azide procedure, and tested for the binding activity to motilin receptor and smooth muscle contractile activity. The cyclic peptides 3, 4, and 5 showed antagonistic property on contraction assay (pA2 [the negative logarithm of molar concentration of antagonist causing a 2-hold shift to the right of the concentration-response curve for motilin]: 4.5, 4.34, and 4.04, respectively, in rabbit duodenum) and no contractile activity even at high concentration.

Amino Acid Sequence↗

PubMed2001

Algae-removal performance of a fluidized-bed biofilm reactor system for lake water treatment.

The algae removal efficiency of a pilot plant--based on a fluidized-bed biofilm reactor system for treating--was investigated. This system does not require back-washing because the fluidized-bed suffers no clogging. Moreover, the system uses dissolved oxygen in the influent water for aerobic biological treatment without the need for additional aeration equipment. This, it is an easy-maintenance, low-energy system for purifying eutrophic lake water. The system was operated continuously at a flow rate of 1500 m3/d for nine months at Tsuchiura Port in Lake Kasumigaura. And concentrations of chlorophyll-a and dissolved oxygen in both the influent and effluent water were continuously monitored. In summer (August to September) when water bloom occurred, the average efficiency of chlorophyll-a removal was 64% at an average influent chlorophyll-a concentration of 137.8 micrograms/L. Over the entire experimental period of nine months, the average daily amount of removed chlorophyll-a was 40.3 g/d at an average influent chlorophyll-a concentration of 89.5 micrograms/L. By analyzing the relationship between the amount of removed chlorophyll-a and the consumption of dissolved oxygen, it was estimated that almost all of the algae trapped in the reactor was biologically degraded.

Biofilms↗

PubMed2001

Chemical oxidation of organic matter in secondary-treated municipal wastewater by using methods involving ozone, ultraviolet radiation and TiO2 catalyst.

The efficiencies of chemical oxidation of organic matter in genuine secondary-treated municipal wastewater by using O3, O3/UV, O3/TiO2, UV/TiO2 and O3/UV/TiO2 methods were compared experimentally. Effects of carbonates on these efficiencies were also investigated. Elimination of carbonates from the water increased TOC reduction efficiency of all the methods. The effect of the carbonates on the O3 method was less significant than that on the other methods. The O3/UV method was the most effective for reducing TOC under both carbonate-present and decarbonated conditions. The catalytic ozone process (O3/TiO2) showed a tendency to increase the ozonation efficiency at the beginning of the reaction under the decarbonated condition, but the addition of the TiO2 catalyst inhibited the ozonation under the carbonate-present condition. The photocatalytic oxidation process (UV/TiO2) did not reduce TOC as much as the other methods, but it could reduce TOC over a long time. And the O3/UV/TiO2 method did not show a synergistic effect of ozonation and photocatalytic oxidation. Furthermore, zonation prior to coagulation increased TOC reduction efficiency of coagulation, but this effect was also affected by the carbonates in water.

Carbonates↗

PubMed2000

Subunit composition of AMPA receptors expressed by single hippocampal neurons.

Using a patch-clamp, reverse transcription-polymerase chain reaction (RT-PCR) method, we determined AMPA receptor subunits expressed in neurons in rat hippocampal slices at the single-cell level. In a population of non-pyramidal neurons (type II neurons) expressing AMPA receptors with strong inward rectification and Ca2+ permeability, no GluR2 was detected, and GluR1 and GluR4 were the most frequently detected subunits. Analysis of the splicing variants revealed that only the flop form of GluR4 was expressed, but both flip and flop forms of GluR1 were expressed in these neurons. In contrast, GluR2 was the most frequently detected subunit both in CA1 pyramidal cells and type I non-pyramidal cells possessing AMPA receptors with outwardly rectifying current-voltage relationships and little Ca2+ permeability.

Alternative Splicing↗

PubMed2000

Classification of fusiform neocortical interneurons based on unsupervised clustering.

A classification of fusiform neocortical interneurons (n = 60) was performed with an unsupervised cluster analysis based on the comparison of multiple electrophysiological and molecular parameters studied by patch-clamp and single-cell multiplex reverse transcription-PCR in rat neocortical acute slices. The multiplex reverse transcription-PCR protocol was designed to detect simultaneously the expression of GAD65, GAD67, calbindin, parvalbumin, calretinin, neuropeptide Y, vasoactive intestinal peptide (VIP), somatostatin (SS), cholecystokinin, alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid, kainate, N-methyl-d-aspartate, and metabotropic glutamate receptor subtypes. Three groups of fusiform interneurons with distinctive features were disclosed by the cluster analysis. The first type of fusiform neuron (n = 12), termed regular spiking nonpyramidal (RSNP)-SS cluster, was characterized by a firing pattern of RSNP cells and by a high occurrence of SS. The second type of fusiform neuron (n = 32), termed RSNP-VIP cluster, predominantly expressed VIP and also showed firing properties of RSNP neurons with accommodation profiles different from those of RSNP-SS cells. Finally, the last type of fusiform neuron (n = 16) contained a majority of irregular spiking-VIPergic neurons. In addition, the analysis of glutamate receptors revealed cell-type-specific expression profiles. This study shows that combinations of multiple independent criteria define distinct neocortical populations of interneurons potentially involved in specific functions.

Action Potentials↗

PubMed2000

Regulation of kinetic properties of GluR2 AMPA receptor channels by alternative splicing.

The four subunits of the AMPA-type glutamate receptor (GluR1-GluR4 or GluR-A-GluR-D) exist in two distinct forms, flip and flop, generated by alternative splicing of a 115 bp region. The GluR2 subunit plays a key role in determining the functional properties of the AMPA receptor channel. In this study, we examined the differences in kinetic properties between the flip and flop splice variants of the GluR2 subunit expressed in Xenopus oocytes using fast agonist application techniques. Glutamate was applied to outside-out patches from oocytes with piezo-driven double-barreled application pipettes. Because homomeric receptor channels composed of the edited form of GluR2 (GluR2R) produce no appreciable current responses, we expressed the unedited form of GluR2 (GluR2Q) in oocytes, which produced large current responses sufficient for analysis of the kinetic properties. The time constant for desensitization during application of 1 mM glutamate was 5.89 +/- 0. 17 msec (n = 50) in flip and 1.18 +/- 0.05 msec (n = 37) in flop. The deactivation time constant was 0.62 +/- 0.06 msec (n = 10) in flip and 0.54 +/- 0.05 msec (n = 10) in flop. The steady-state nondesensitizing current was 6.8 +/- 0.4% (n = 53) of the peak current in flip, whereas it was almost negligible in flop, being only 1.1 +/- 0.1% (n = 36). The slower desensitization kinetics and larger steady-state current responses in the flip variant were also observed in heteromeric receptors assembled from GluR2Q/GluR2R. Thus, desensitization occurred much more prominently in the flop variant in the recombinant GluR2 receptor channels.

Alternative Splicing↗

PubMed2000

Transthyretin binds amyloid beta peptides, Abeta1-42 and Abeta1-40 to form complex in the autopsied human kidney - possible role of transthyretin for abeta sequestration.

The deposition of amyloid beta protein (Abeta), a proteolytic cleavage product of amyloid precursor protein (APP), is an invariable pathological feature of the Alzheimer's disease brain, while APP gene is widely expressed in all neuronal and non-neuronal tissues with the highest levels of expression in the brain, and kidney. To understand the role transthyretin (TTR) plays in the sequestration mechanism of Abeta in the kidney, we have investigated interactions of TTR with Abeta1-40 and Abeta1-42 molecules by an immunoprecipitation method, in vitro binding studies, and overlay assay. These in vivo and in vitro biochemical experiments showed that TTR bound Abeta1-42 preferentially, and Abeta1-40 only to a limited extent, to form TTR-monomer and -dimer-Abeta complexes in the normal human kidney. We provide new evidence supporting the hypothesis that TTR, an Abeta binding protein, plays an important role in the sequestration of Abeta and prevents amyloid formation in the kidney.

Amyloid beta-Peptides↗

PubMed2000

Influenza A virus encephalopathy with symmetrical thalamic lesions.

UNLABELLED: During an epidemic of influenza A infection in Japan, a 7-year-old boy was admitted to our hospital because of high fever, convulsions, coma, and liver dysfunction on the 2nd day of a cold-like illness. His serum CPK was markedly elevated, but there was no hyperammonaemia or hypoglycaemia. His CSF showed an increased protein level, but the cell count and glucose level were normal. CT and MRI of the brain showed symmetrical thalamic lesions, and he was diagnosed with acute necrotizing encephalopathy in childhood. He had a significant increased in antibodies to influenza A H1N1 in serum and CSF, but the CSF was negative for influenza virus using virus isolation and a polymerase chain reaction assay. CONCLUSION: Antibody production without detectable levels of influenza virus in cerebrospinal fluid suggests that virus infection occurred, but the virus did not replicate in sufficient numbers in his central nervous system. The thalamic lesion, the hallmark of acute necrotizing encephalopathy in childhood, may be initiated by a local virus infection and develop with subsequent local changes such as breakdown of the blood-brain barrier and the extravasation of blood.

Acute Disease↗

PubMed2000

Bilateral same day surgery for bilateral perforated chronic otitis media.

OBJECTIVE: Bilateral same day surgery has been performed rarely because of the risk of postoperative sensorineural hearing loss following conventional myringoplasty or tympanoplasty (CMT). Simple underlay myringoplasty (SUM) through the ear canal has been developed by Yuasa R, Saijo S, Tomioka Y, et al. Office closure of eardrum perforation with fibrin glue (in Japanese), Otolaryngol Head Neck Surg (Tokyo) 1989;61:1117-1122, which has little risk of sensorineural hearing loss. We tried bilateral same day surgery using this technique and evaluated its outcome. METHODS: Of 86 cases with bilateral perforated chronic otitis media that we treated between 1995-1997, 25 cases underwent bilateral same day surgery. Bilateral SUMs was performed on seven patients, SUM and CMT on 16 patients, and bilateral CMTs on two patients. RESULTS: Closure of perforation was successful in 18 patients (72%) on both sides and in seven patients (28%) on one side. Postoperative air-bone gap of less than 20 dB was achieved in 15 cases (60%) on both sides and in 23 cases (92%) on one side. CONCLUSION: Bilateral same day surgery for bilateral perforated chronic otitis media is possible if the operative indications are considered.

Adolescent↗

PubMed2000

A pleomorphic adenoma of the lacrimal gland in a dog.

A 13-year-old female mongrel dog had a pleomorphic adenoma of the lacrimal gland in the right upper orbit. The tumor measured 3.8 x 3.0 x 3.3 cm, appeared white, round, and firm, and pressed the right globe and surrounding tissues. Histopathologically, the tumor had a thin connective tissue capsule and was composed of tubules with two cell types, some resembling luminal epithelial cells making up the tubular structures and the other of myoepithelial cells. Epithelial tubules were disposed in an adenomatous fashion and separated from each other by proliferating pleomorphic myoepithelial cells. Immunohistochemically, large numbers of the luminal epithelial cells revealed an immunopositive reaction against keratin/cytokeratin (AE1/AE3), and some epithelial cells reacted against cytokeratin 14. Spindle-shaped myoepithelial cells revealed an immunopositive reaction against cytokeratin 14, alpha-smooth muscle actin, and vimentin. A small number of myoepithelial cells reacted against desmin. S-100 protein immunopositivity was frequently found in luminal epithelial cells and rarely in the pleomorphic myoepithelial cells. Glial fibrillary acidic protein positivity was commonly found in myoepithelial cells, myxoid matrices, and intracystic materials, but not in luminal epithelial cells.

Actins↗

PubMed1999

Selective excitation of subtypes of neocortical interneurons by nicotinic receptors.

The cellular mechanisms by which neuronal nicotinic cholinergic receptors influence many aspects of physiology and pathology in the neocortex remain primarily unknown. Whole-cell recordings and single-cell reverse transcription (RT)-PCR were combined to analyze the effect of nicotinic receptor agonists on different types of neurons in acute slices of rat neocortex. Nicotinic receptor agonists had no effect on pyramidal neurons and on most types of interneurons, including parvalbumin-expressing fast spiking interneurons and somatostatin-expressing interneurons, but selectively excited a subpopulation of interneurons coexpressing the neuropeptides vasoactive intestinal peptide (VIP) and cholecystokinin. This excitation persisted in the presence of glutamate, GABA, and muscarinic receptor antagonists and in the presence of tetrodotoxin and low extracellular calcium, suggesting that the depolarization was mediated through the direct activation of postsynaptic nicotinic receptors. The responses were blocked by the nicotinic receptor antagonists dihydro-beta-erythroidine and mecamylamine and persisted in the presence of the alpha7 selective nicotinic receptor antagonist methyllycaconitine, suggesting that the involved nicotinic receptors lacked the alpha7 subunit. Single-cell RT-PCR analysis indicated that the majority of the interneurons that responded to nicotinic stimulation coexpressed the alpha4, alpha5, and beta2 nicotinic receptor subunits. Therefore, these results provide a role for non-alpha7 nicotinic receptors in the selective excitation of a subpopulation of neocortical interneurons. Because the neocortical interneurons expressing VIP have been proposed previously to regulate regional cortical blood flow and metabolism, these results also provide a cellular basis for the neuronal regulation of cortical blood flow mediated by acetylcholine.

Acetylcholine↗