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Biomedical subjects

H Hatanaka

Publications and source records attributed to H Hatanaka.

At least 181 records · Page 10Linked to original sources
PubMed1994

Partial deuteration and blood-brain barrier (BBB) permeability.

Boron neutron capture therapy (BNCT) is one method of radio-surgery used for malignant brain tumor. The theory of this method is based on the nuclear reaction that occurs when boron-10 is radiated with and absorbs neutrons. When treating deep-seated brain tumor, partial deuteration of body water is used to improve the penetration of neurons into the tissue. In order to investigate the change in the BBB function under partial deuteration, we measured brain water content and the permeability of protein. Wistar rats were given 99% heavy water (approx. 10% of body weight/day) as drinking water. On the day of the experiment, all animals received 125-I labeled albumin as a tracer of protein. Light water in the control group or heavy water (D2O) in the experimental group was given by drip infusion for 60 min. Heavy water was measured by infrared spectroscopic analysis. Water content was measured by the freeze-dry method. The radioactivity of 125-I was determined with a gamma scintillation counter. Mean values of D2O concentration in the tissue were 17.9-36.5%. Water content increased in the cortex in all animals. The ratio of 125-I in the brain tissue to blood showed significant differences between the control group and animals deuterated to more than 30% of body water. Brain tissue deuterated over 10% showed a mild leakage of water, indicating the early stage of brain edema. Deuteration higher than 30% caused a leakage of protein, which might indicate the leakage of boron compound from the vessels into the normal brain tissue.

Animals↗
PubMed1994

Evidence for an origin of ethyl-nitrosourea-induced rat central nervous system tumors from pluripotent germinal neuroepithelium.

Brain tumors induced by transplacental application of ethyl-nitrosourea (ENU) in F344 rats were immunohistochemically demonstrated to consist of undifferentiated cells, astriocyte-like cells, oligodendroglia-like cells, and two distinct types of vimentin-expressing cell groupings termed as perivascular small cell nests (PSCNs) and large cell nests (LCNs). Co-distribution of vimentin and glial fibrillary acidic protein (GFAP) was sparsely observed in the astrocyte-like cells, which suggested an immature glial phenotype. PCSNs contained cells expressing GFAP, neuron-specific enolase (NSE), beta-tubulin isotype III, and low-affinity nerve growth factor receptors (LNGFRs). LCNs contained cells showing a neuronal phenotype with expression of low- and middle-molecular mass neurofilament proteins (NF-L and -M) as well as NSE, beta-tubulin isotype III and LNGFR. Double-labelling immunohistochemistry revealed the NF-L-expression in LNGFR-positive LCN-forming cells. Oligodendroglia-like cells and their intercellular neuropil-like structures expressed beta-tubulin isotype III, synaptophysin and NSE, in addition to the expressions of vimentin and GFAP. Electron microscopically, synapse-like structures were formed between these oligodendroglia-like cells and their dendritic processes. Topographically, bidirectional cell transitions from PSCNs to astrocytes and LCNs were indicated. The present study strongly suggests that so-called ENU-induced "gliomas" originate from pluripotent germinal neuroepithelium. Furthermore, LNGFR expression may be responsible for acquisition of neuronal phenotype in these tumors.

Animals↗
PubMed1994

Death of cultured postnatal rat CNS neurons by in vitro hypoxia with special reference to N-methyl-D-aspartate-related toxicity.

We have established an in vitro hypoxia model using cultured central nervous system neurons from postnatal 4-day-old (P4) rats, in which death may be correlated with N-methyl-D-aspartate (NMDA)-related toxicity. P4 rat hippocampal and neocortical neurons in culture were prevented from death by the addition of MK-801, an NMDA receptor antagonist, and also partially by the removal of calcium ions from the medium, suggesting that NMDA receptors were associated with neuronal death in this in vitro hypoxia model. The neuronal death induced by the model was attenuated by the addition of alpha-tocopherol, indicating that free radicals emerged after hypoxia. This event seems similar to the hypoxia-reoxygenation phenomenon in in vitro hypoxia. Continuous treatment with basic fibroblast growth factor (bFGF) during hypoxia, and bFGF pretreatment for 6 h and removal before hypoxia induced the resistance to hypoxia-mediated cell death.

Animals↗
PubMed1994

Structure of the N-terminal SH3 domain of GRB2 complexed with a peptide from the guanine nucleotide releasing factor Sos.

Src-homology 3 (SH3) domains mediate signal transduction by binding to proline-rich motifs in target proteins. We have determined the high-resolution NMR structure of the complex between the amino-terminal SH3 domain of GRB2 and a ten amino acid peptide derived from the guanine nucleotide releasing factor Sos. The NMR data show that the peptide adopts the conformation of a left-handed polyproline type II helix and interacts with three major sites on the SH3 domain. The orientation of the bound peptide is opposite to that of proline-rich peptides bound to the SH3 domains of Abl, Fyn and p85.

Adaptor Proteins, Signal Transducing↗
PubMed1994

FR901451, a novel inhibitor of human leukocyte elastase from Flexibacter sp. I. Producing organism, fermentation, isolation, physico-chemical and biological properties.

A novel human leukocyte elastase (HLE) inhibitor, FR901451 was discovered in the fermentation broth of a bacteria. The bacteria was identified as Flexibacter sp. No. 758. FR901451 has a molecular weight of 1269 and a molecular formula of C60H79N13O18. The mode of inhibition against HLE is competitive, with a Ki value of 9.8 x 10(-9) M.

Animals↗
PubMed1994

[Neuronal cell death and apoptosis].

Neuronal cell death is thought to be an important phenomenon not only for the developmental but also for the post-matured stages of the PNS and CNS neurons. In the developmental stages, massive neuronal death is observed at specific periods, e.g. the immediately after the arrival of axons to the postsynaptic target fields. This phenomenon is precisely programmed in the developing nervous system, so that they are called physiological or naturally occurring neuronal death. It has been shown that this programmed neuronal death is mediated by apoptotic death cascade, as follows: 1) neurotrophic agents, such as nerve growth factor, or afferent electrical input prevent neuronal death; 2) the macromolecular synthesis inhibitors, such as cycloheximide or actinomycin-D, prevent cell death; 3) DNA fragmentation is detected during the course of cell death; 4) variations of apoptotic morphology are observed in programmed neuronal death. Furthermore, recent studies also suggest that such apoptotic neuronal death occurs in the matured nervous system, e.g. neuro-degenerative diseases, such as Alzheimer's and Parkinson's diseases, or aging. Thus, it is expected that the study of apoptosis in the nervous system give us useful clues to know how the neuronal network are constructed in the development and why the neurodegenerative disease and brain aging occur.

Alzheimer Disease↗
PubMed1993

A basic transthyretin variant (Glu61-->Lys) causes familial amyloidotic polyneuropathy: protein and DNA sequencing and PCR-induced mutation restriction analysis.

A new mutation of transthyretin (TTR) has been identified in a patient with late-onset familial amyloidotic polyneuropathy (FAP) of Japanese origin. Peptide mapping by reverse-phase high performance liquid chromatography to compare the patient's TTR with normal TTR showed the presence of an abnormal peptide. Amino acid sequence analysis of the peptide (residues 49-61) showed a lysine-for-glutamic acid substitution at position 61. This substitution, verified by direct DNA sequencing, was the result of a guanine to adenine change on exon 3 of the TTR gene. A polymerase chain reaction-induced mutation restriction analysis (PCR-IMRA) system was established to rapidly detect the missense mutation. TTR-Lys61 is the first variant TTR with a replacement of the acidic with basic amino acid to be found in the amyloid precursor proteins of FAP.

Aged↗
PubMed1993

Solution structure of the SH3 domain of phospholipase C-gamma.

SH3 (Src homology 3) domains are found in many signaling proteins and appear to function as binding modules for cytoplasmic target proteins. The solution structure of the SH3 domain of human phospholipase C-gamma (PLC-gamma) was determined by two-dimensional 1H NMR analysis. This SH3 domain is composed of eight antiparallel beta strands consisting of two successive "Greek key" motifs, which form a barrel-like structure. The conserved aliphatic and aromatic residues form a hydrophobic pocket on the molecular surface, and the conserved carboxylic residues are localized to the periphery. The hydrophobic pocket may serve as a binding site for target proteins. Analysis of the slowly exchanging amide protons by NMR measurements indicates that despite containing a high content of beta structure, the SH3 domain of PLC-gamma is flexible.

Amino Acid Sequence↗
PubMed1993

Small subunits of Photosystem I reaction center complexes from Synechococcus elongatus. I. Is the psaF gene product required for oxidation of cytochrome c-553?

Photosystem I (PS I) reaction center complexes isolated from the thermophilic cyanobacterium Synechococcus elongatus with nonionic detergents, digitonin or sucrose monolaurate, contained eight small subunit polypeptides. Two of the small polypeptides were identified by analysis of their N-terminal amino-acid sequences as the psaF and psaE gene products. Treatment with a cationic detergent, cetyltrimethylammonium bromide, resulted in depletion of five small subunits including the psaF gene product. Five PS I complexes isolated with an anionic detergent, sodium dodecylsulfate, contained zero to four small subunits but were all depleted of the psaF polypeptide. The function of the psaF gene product was examined by measuring reduction kinetics of flash-oxidized P-700 in the presence of different concentrations of cytochrome c-553. Oxidized P-700 was rapidly reduced by the reduced cytochrome in all the PS I complexes that contained, at least, the psaC and psaD polypeptides and the second-order rate constants of electron transfer from cytochrome c-553 to P-700 were essentially the same between PS I complexes that contained the psaF polypeptide and those that lost this polypeptide. Thus, the psaF polypeptide is not required for the bimolecular reaction between P-700 and cytochrome c-553. Mg2+ had a moderate stimulating effect on the rate of P-700 reduction whether PS I complexes were associated with the psaF gene product or not. The function of this subunit polypeptide is discussed.

Amino Acid Sequence↗
PubMed1993

Small subunits of Photosystem I reaction center complexes from Synechococcus elongatus. II. The psaE gene product has a role to promote interaction between the terminal electron acceptor and ferredoxin.

Function of a subunit polypeptide (the psaE gene product) of Photosystem I (PS I) reaction center complexes was investigated by comparing the reactivity of the reduced iron-sulfur centers (FA/FB)- with ferredoxin among Synechococcus PS I complexes which had been variously depleted of this polypeptide. Ferredoxin at or below 1 microM can accept electrons from (FA/FB)- effectively competing with the back reaction between P-700+ and (FA/FB)- in the thylakoid membranes and PS I complexes that contained all the eight small subunits. The high reactivity of (FA/FB)- with low concentrations of ferredoxin was observed in PS I complexes which contain only the products of psaC, psaD and psaE genes but not in complexes which carry the psaC, psaD, psaL and psaK gene products but no psaE gene product. Varied amounts of the psaE gene product were extracted by treatment with different concentrations of a cationic detergent, dodecyltrimethylammonium bromide, and 2.5 M NaCl. The solubilized polypeptide was then reconstituted to the depleted complexes. The magnitudes of the back reaction that could be suppressed by addition of ferredoxin at or below 1 microM were well correlated to the amounts of the psaE polypeptide remained bound or rebound to the complexes. It is concluded that the product of the psaE gene has a role to promote the interaction between the terminal bound electron acceptor and ferredoxin. A high autooxidizability of (FA/FB)- and contrasting effects of lipophilic cations and anions on the rate of the back reaction from (FA/FB)- to P-700+ were also reported.

Cetrimonium↗
PubMed1993

Apoptotic cell death occurs in hippocampal neurons cultured in a high oxygen atmosphere.

When embryonic rat hippocampal neurons were cultured in a 50% oxygen atmosphere, neurons gradually died after 20 h in culture. This death pattern was found to be mediated by an intracellular active death program, so called apoptosis, as follows: (1) Cycloheximide and actinomycin-D, protein and RNA synthesis inhibitors, respectively, prevented cell death, indicating that cell death required new protein biosynthesis. (2) DNA fragmentation (called a "DNA ladder"), a specific biochemical marker of apoptosis, was detected during the course of cell death. (3) Depolarization with high K+ medium (26-50 mM) prevented cell death. This effect was suppressed by some dihydropyridine derivatives, L-type Ca channel blockers, such as nifedipine and nicardipine. These results indicate that increased levels of oxygen activate an apoptotic mechanism in the cultured hippocampal neurons, and suggest that neuronal activity may protect the neurons from oxygen-induced apoptosis.

Animals↗
PubMed1993

In vitro model of hypoxia: basic fibroblast growth factor can rescue cultured CNS neurons from oxygen-deprived cell death.

We established an in vitro hypoxia model and investigated the protective effect of basic fibroblast growth factor (bFGF) against neuronal cell death caused by hypoxia. Hippocampal neurons obtained from rats on embryonic day (E) 17 and 20 and on postnatal day (P) 4 were cultured for 6-24 h in an oxygen-deprived state. This in vitro hypoxia study showed that the cultured neurons were sensitive to the oxygen deprivation. The cultured P4 rat hippocampal neurons seemed to be weaker in the hypoxia condition than those of E17 and E20 rats, suggesting that the cultured postnatal cells might be sensitive to hypoxia. bFGF, but not nerve growth factor, prevented the neuronal cell death caused by hypoxia in a dose-dependent manner.

Animals↗
PubMed1993

FR901277, a novel inhibitor of human leukocyte elastase from Streptomyces resistomycificus. Producing organism, fermentation, isolation, physico-chemical and biological properties.

A novel human leukocyte elastase inhibitor, FR901277 was discovered in the fermentation broth of Streptomyces resistomycificus No. 7622. FR901277 has a molecular weight of 961 and a molecular formula of C47H63N9O13. The mode of inhibition is competitive, with a Ki of 1.2 x 10(-8) M. Oral administration of FR901277 at doses from 32 to 320 mg/kg significantly prevented human leukocyte elastase-induced foot edema in mice.

Animals↗
PubMed1993

Improved bioavailability of para-boronophenylalanine by cyclodextrin complexation.

This study was undertaken to develop an oral dosage form for para-boronophenylalanine (BPA) plus cyclodextrin (CD) for use in the thermal neutron capture therapy for malignant melanoma. Powders of the BPA and CD complexes were obtained in a molar ratio of 1:2. X-ray diffraction of the BPA-CD complexes showed halo patterns that indicated that each complex was in a new solid state as an amorphous compound. The enhancement of BPA solubility by glucosyl (G1)- and maltosyl (G2)-alpha-CD was greater than that with the other CDs. The isolation rate of BPA from its complex was different for each BPA-CD complex. The bioavailability of BPA in rats was improved with oral administration of the BPA-alpha-CD, G1-alpha-CD, and G2-alpha-CD complexes. In contrast, a complex of BPA and dimaltosyl (G2G2) or G2-beta-CD, which had low release rate and low solubility, did not improve the bioavailability of BPA. These results indicate that the solubility and release rate of BPA from a complex in solution are important for the bioavailability of BPA after oral administration of BPA-CD complexes.

Animals↗
PubMed1992

Basic fibroblast growth factor rescues CNS neurons from cell death caused by high oxygen atmosphere in culture.

In the present study, we cultured rat CNS neurons and tested the neurotrophic support provided by basic fibroblast growth factor (bFGF) to prevent the oxygen-induced neuronal cell death. When rat basal forebrain (septum and vertical limb of diagonal band of Broca) cells of embryonic day 20 were cultured in a serum-free medium containing 5 microM cytosine arabinoside in a 50% oxygen atmosphere, the neuronal cells, which were immunostained by an anti-microtubule-associated protein 2 (MAP2) antibody, gradually died after 1 day in culture. After 3.5 days in culture, only 2-5% of neuronal cells survived. This oxygen-induced cell death of cultured basal forebrain neurons was reversed by the addition of bFGF at a concentration of 100 ng/ml. This cell-saving effect was dose-dependent, and the ED50 value was 12 ng/ml. Nerve growth factor (NGF) and insulin-like growth factor II could not prevent cell death. The activity of choline acetyltransferase was also maintained when bFGF was present in the basal forebrain culture. Viable astroglial cells, which were immunostained by an anti-glial fibrillary acidic protein, accounted for a few percent of the total number of cells after 3 days in culture both with and without 100 ng/ml of bFGF. The survival-enhancing effect of bFGF was observed not only in basal forebrain neurons but also in neocortical and hippocampal neurons. However, the sensitivity to oxygen toxicity of cultured neurons from the 3 CNS regions varied greatly. The neocortical neurons were the most sensitive to oxidative stress, while the hippocampal neurons were the most resistant. These results suggest that bFGF plays an important role in saving neuronal cells from oxidative stress during their long life without division.

Animals↗
PubMed1992

Structure-activity relationships of mu-conotoxin GIIIA: structure determination of active and inactive sodium channel blocker peptides by NMR and simulated annealing calculations.

A synthetic replacement study of the amino acid residues of mu-conotoxin GIIIA, a peptide blocker for muscle sodium channels, has recently shown that the conformation formed by three disulfide bridges and the molecular basicity, especially the one around the Arg13 residue, are important for blocking activity. In the present study, we determined the three-dimensional structure of an inactive analog, [Ala13]mu-conotoxin GIIIA, and refined that of the native toxin by NMR spectroscopy combined with simulated annealing calculations. The atomic root-mean-square difference of the mutant from the native conotoxin was 0.62 A for the backbone atoms (N, C alpha, C') of all residues except for the two terminal residues. The observation that the replacement of Arg13 by Ala13 does not significantly change the molecular conformation suggests that the loss of activity is not due to the conformational change but to the direct interaction of the essential Arg13 residue with the sodium channel molecules. In the determined structure, important residues for the activity, Arg13, Lys16, Hyp(hydroxyproline)17, and Arg19, are clustered on one side of the molecule, an observation which suggests that this face of the molecule associates with the receptor site of sodium channels. The hydroxyl group of Hyp17 is suggested to interact with the channel site with which the essential hydroxyl groups of tetrodotoxin and saxitoxin interact.

Alanine↗
PubMed1992

Effects of nerve growth factor and basic fibroblast growth factor on survival of cultured septal cholinergic neurons from adult rats.

We have established a primary culture technique for neuronal cells from rat basal forebrain from postnatal day 58 (P58) to study the effects of neurotrophic factors on the neurons. The survival of acetylcholinesterase (AChE)-positive neurons of 2-week-old rat septum has already been reported to be strongly supported by nerve growth factor (NGF) in culture. In this culture study of neurons from adult rat brains, the survival of AChE-positive neurons from P58 rat septum was slightly improved by NGF, although low affinity NGF receptor expression was also observed on cultured P58 rat septum neurons as well as on those from 2-week-old rats. The addition of basic fibroblast growth factor (bFGF) improved the survival of AChE-positive neurons cultured from P58 rat septum, but did not promote the survival of neurons from P12 rat septum. These results suggest that NGF changes to a maintenance factor in adult rat brain from a survival factor in postnatal 2-week-old rats. The survival of cholinergic neurons in culture of adult rat septum might be supported by factor(s) other than NGF, such as bFGF.

Acetylcholine↗