PubMed Health⌕ Search

Biomedical subjects

M Doi

Publications and source records attributed to M Doi.

At least 163 records · Page 9Linked to original sources
PubMed1996

[A case of acute occlusion of left middle cerebral artery due to an embolus treated successfully with percutaneous transluminal angioplasty].

The acute occlusion of cerebral artery by embolism causes severe cerebral infarction. In cases with poor colateral circulation, cerebral infarction develops more severely. In these cases, quick recanalization of the occluded cerebral artery is necessary to prevent severe hemorrhagic infarction and brain edema. We report a case where interventional techniques were used to bring about quick recanalization of occluded cerebral artery. We encountered a case of a sixty-year-old male who experienced complete occlusion of the left middle cerebral artery due to an embolus. It was very hard to pass a guide wire through the embolic lesion. At first, we tried mild local fibrinolysis therapy using tissue plasminogen activator, but we could not get any recanalization. However, after mild local fibrinolysis therapy, the guide wire could be passed through the occlusion point. Secondly, we tried percutaneous transluminal angioplasty (PTA) with 2.0mm diameter angioplastic balloon using up to five atomic pressures, after which we obtained partial recanalization. Finally we achieved total recanalization of the middle cerebral artery by PTA with a 2.5mm diameter angioplastic balloon. We crushed this embolus using the angioplastic balloon with up to six atomic pressures. The point of the techniques is to press the embolus against the arterial wall. After this angioplasty, there was an occlusion of the common trunk of the posterior parietal artery and the angular artery. However there was neither massive hemorrhagic infarction nor massive brain edema on follow up CT. In the treatment of acute occlusion of the cerebral artery due to embolism, we found PTA is very effective against the embolus. In the future, we need to develop a retrieving device and a balloon that will prevent the production of small emboli during the crush process involved when bringing about recanalization using PTA.

Acute Disease↗
PubMed1995

Effects of local anaesthesia on formalin-induced Fos expression in the rat dorsal horn.

A subcutaneous injection of formalin into foot pad of the rat produces a bimodal nociceptive response including an early intense response in the first 5 min and a later moderate response that is exhibited from 20 to 60 min after injection. In this study, we investigated the effects of blocking the early phase and late phase input, respectively, on Fos-like immunoreactivity (Fos-LI) expression in dorsal horn neurones. Rats of the early phase block (EB) group were injected with 5% formalin (0.05 ml) into the footpad 5 min after a s.c. injection of 4% lidocaine (0.15 ml) into the angle. The rats of the late phase block (LB) group were injected with 5% formalin into the footpad 10 min before the s.c. injection of 3% prilocaine (0.20 ml) containing felypressin into the ankle. The rats of the control group were given the formalin injection alone. Fos-LI was detected in the dorsal horn 2 h after the formalin injection. The numbers of Fos-LI neurones in the dorsal horn of both EB and LB group were markedly decreased compared with the control group, being 31.3% (laminae I-III of EB), 37.1% (laminae I-III of LB), 13.9% (laminae IV-VI of EB) and 16.2% (laminae IV-VI of LB) of the control values. No significant difference was observed between EB and LB group. These findings suggested that the early and late phase contribute in concert to the induction of genetic changes in dorsal horn neurones after formalin injection.

Anesthesia, Local↗
PubMed1995

Enhancement of aromatic amino acid-nucleic acid base stacking interaction by metal coordination to base: fluorescence study on a tryptophan-Pt(II)-guanine ternary complex.

In order to investigate the effect of the Pt(II) ion on the stacking interaction between tryptophan and a guanine base, the quenching of Trp fluorescence was monitored for some systems in the absence and presence of the metal ion, and the association constants were obtained by the analysis of Eadie-Hofstee plots. All spectral data suggested that the stacking interaction is enhanced by the Pt(II) coordination to the guanine N7 atom. The result indicates the importance of the metal ion as a bookmark in the specific recognition of a nucleic acid base by an aromatic amino acid residue.

Base Composition↗
PubMed1995

Morphological classification of retinal ganglion cells in mice.

Mice have been used for extensive studies on optic nerves and retinal ganglion cells, but mouse retinal ganglion cells have not been classified morphologically. In the present study, normally placed retinal ganglion cells and displaced retinal ganglion cells in pigmented and albino mice were classified morphologically using horseradish peroxidase. These cells were classified into three types according to the sizes of the soma and the dendritic field: type I cells, large soma and large dendritic field; type II cells, small-to-medium soma and small dendritic field; and type III cells, small-to-medium soma and large dendritic field. Some ganglion cells had both symmetric and asymmetric cells. Each type was further subdivided according to the termination level of dendrites in the inner plexiform layer and the dendritic branching pattern. Except for type III displaced ganglion cells, dendrites of the normally placed ganglion cells and the displaced ganglion cells ramify in the outer two-fifths of the inner plexiform layer (sublamina a) or the inner three-fifths of the inner plexiform layer (sublamina b). Type III displaced ganglion cells ramify only in sublamina a. Dendrites of some normally placed type I ganglion cells ramify in both sublaminae. Displaced biplexiform cells were observed, the dendrites of which ramify in both the inner and the outer plexiform layers. All cell types were found in both mouse strains.

Animals↗
PubMed1995

Calbindin-D 28k immunoreactivity in the cerebellum of spinocerebellar degeneration.

We studied immunoreactivity for calbindin-D 28k (CaBP), an intracellular calcium-binding protein, in the cerebellum of control subjects and of patients with spinocerebellar degeneration (SCD) including sporadic olivopontocerebellar atrophy and familial cortical cerebellar atrophy. In the cerebellum, CaBP immunoreactivity was seen exclusively in the Purkinje cell in both SCD and control groups. However, the number of CaBP-immunoreactive Purkinje cells was significantly reduced in SCD. CaBP immunohistochemistry also disclosed abnormal morphological changes of Purkinje cells, which was not visualized on conventional strains or not clearly demonstrated on immunohistochemistry for neurofilaments. Moreover, reduced CaBP immunoreactivity was observed even in some remaining Purkinje cells of SCD suggesting that loss of CaBP precedes neuronal loss of Purkinje cell. We conclude that CaBP is a useful marker for Purkinje cell degeneration, and that reduced CaBP expression might have some association with the mechanism of the Purkinje cell degeneration in SCD.

Aged↗
PubMed1995

Conserved delta-activity in reverse enantiomeric opioid peptide.

A reverse enantiomeric peptide has a reversed amino acid sequence with enantiomeric amino acid residues compared with its parent peptide. In most cases the random change of amino acid sequence or chirality might be expected to bring about significant changes in peptide activity. However, the reverse enantiomeric peptides of Leu-enkephalin and Tyr-D-Ala-Gly-Phe-D-Leu (DADLE) have shown affinity for the opioid delta-receptor, but not for mu- or kappa-receptors. This suggests that delta-opioid receptor recognition occurs primarily through interaction with the peptide side chains, since the native opioid peptide and its reverse enantiomer are able to have similar side-chain conformation.

Amino Acid Sequence↗
PubMed1995

Histopathology of rabbit eyes with silicone-fluorosilicone copolymer oil as six months internal retinal tamponade.

Silicone-fluorosilicone copolymer oil has low viscosity (175-185 cSt) and is heavier than water (density, 1.16 g cm-3). Short term retinal tolerance (within 2 months) of the silicone-fluorosilicone copolymer oil has been reported to be the same as that of currently used intraocular silicone oil. Ocular response of the purified silicone-fluorosilicone copolymer oil were examined clinically and histopathologically from 2.5 months to 6 months after vitreous cavity injection in rabbit phakic eyes, and compared the oil tolerance with that of purified silicone oil (0.97 g cm-3, 5000 cSt). The effects in anterior chamber also were examined within 4 weeks of the silicone-fluorosilicone copolymer oil injection in different rabbits. Silicone-fluorosilicone copolymer oil recovered from the vitreous cavity at 6 months was analysed for cholesterol and retinol content by high performance liquid chromatography. Because of its low viscosity, silicone-fluorosilicone copolymer oil was easy to inject and remove from the vitreous cavity with a 20-G needle. After the vitreous injection, discrete droplet formation by the silicone-fluorosilicone copolymer oil occurred more easily than by silicone oil. Medullary ray detachment was seen in a silicone oil-, and some silicone-fluorosilicone copolymer oil-injected eyes at 4-6 months. Histopathologically, after 3-6 months disappearance of outer plexiform layer and disorganization of the photoreceptor layer of silicone oil-, and silicone-fluorosilicone copolymer oil-injected eyes were seen in the superior and the inferior retina, respectively. Migration of the photoreceptor cell nuclei to the photoreceptor layer was found in the inferior retina of silicone-fluorosilicone copolymer oil-injected eyes at 5-6 months. Small droplets ingested by mononuclear cells were found in the vitreous cavity or preretina at 4-6 months in silicone-fluorosilicone copolymer oil-injected eyes. After the anterior chamber injection, silicone-fluorosilicone copolymer oil induced endothelial cell damage in the area where the oil contacted continuously. Retinol and cholesterol were identified in silicone-fluorosilicone copolymer oil removed from the vitreous cavity. Silicone-fluorosilicone copolymer oil may be useful as an intraoperative device in retinal detachment surgery and as a short term (up to about 2 months) retinal tamponade but we do not recommend it for long term retinal tamponade.

Animals↗
PubMed1995

Analysis of the chromosomal localization of the repetitive sequences (RPSs) in Candida albicans.

The location and organization of repetitive sequences, members of the RPS family, which are sequences specific to Candida albicans, were determined on each chromosome of C. albicans strain FC18. Using pulsed-field gel electrophoresis, we separated seven fractions from eight chromosomes. Each chromosome was cleaved by BamHI and XhoI to excise the RPSs, which were then detected by hybridization with an RPS probe. All chromosomes except chromosome 4 carried RPSs, and these RPSs were located within a limited region on each chromosome. From the digestion of each chromosome with SfiI and probing with the RPSs, we found that these recognition sites within the RPS region were conserved among all RPS-containing chromosomes. For further characterization of the RPSs, the locations and the boundary regions of the RPSs were examined on chromosome 6 of strain FC18 as a model chromosome. Using the restriction enzymes SfiI, SmaI, XhoI, BamHI, MluI and NruI, we constructed a semi-macro physical map of the RPSs and their boundary regions on this chromosome. We also determined which part of the RPS was adjacent to each boundary by using sub-fragments of RPS as probes. The physical configuration around the RPSs and their boundary regions are presented. The results obtained should be useful for future analysis of the function of these regions.

Blotting, Southern↗
PubMed1995

Solution structure of a human calcitonin analog elucidated by NMR and distance geometry calculations.

Three-dimensional structure of a human calcitonin analog (abbreviated as hCTa) in which the amino acids of the wild type are replaced at position 12, 16 and 19 by leucine residues and further at position 22 by a tyrosine residue was studied in TFE solution by 1H-NMR and distance geometry calculations. This analog has a 15-20 times activity as compared with the wild type. The amino acid replacements resulted in formation of an amphiphilic alpha-helix in the region between the residues 4-20. The overall three-dimensional structure is similar to that of the wild type. The conformational feature of hCTa with a hydrophobic face composed with a Met and four Leu residues may be related to its higher hypocalcemic potency.

Amino Acid Sequence↗
PubMed1995

Soluble expression of a synthetic gene for human translation initiation factor 4E in Escherichia coli.

In order to obtain the active form of recombinant human initiation factor (eIF) 4E effectively, an artificial synthetic gene was cloned into an expression vector (pMAL-p2) and the soluble expression was attempted in Escherichia coli under the control of a tac promoter. Two expression systems were finally constructed as a fusion protein with maltose-binding protein, which contain a recognition sequence for the site specific protease alpha-thrombin and factor Xa, respectively. Most of the fusion protein was induced as a soluble form. The soluble human eIF-4E digested from the fusion protein showed binding specificity for the m7GTP affinity column.

Amino Acid Sequence↗
PubMed1995

Binding specificity of mutagenic tryptophan pyrolysates for DNA conformation: spectroscopic and viscometric studies.

The compounds, 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1) and 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2), are major potent mutacarcinogens isolated from tryptophan pyrolysate. In order to investigate their interaction with DNA and effects on DNA conformation, studies involving circular dichroism, fluorescence and absorption spectroscopy and viscometric titration were performed. The results show that (a) Trp-P-1 and Trp-P-2 are potent intercalators of DNA with nearly the same specificity for the A-T and G-C (alternative purine-pyrimidine) base sequences, (b) the interaction of Trp-P-1 with the B-form of DNA is biphasic so that stiffening of the B-DNA conformation occurs over the range r ([Trp-P-1]/[DNA]) = 0-2.5, followed by transformation of B to the non-B conformation at r > 2.5, (c) the transformation to the non-B structure is not observed for Trp-P-2, although stiffening of the B-DNA conformation similarly occurs, and (d) both Trp-P-1 and Trp-P-2 promote unwinding of the salt-induced Z-DNA to give the B-form. These data indicate that the noncovalent interaction of Trp-P with DNA is mainly dependent on the B-form conformation.

Base Sequence↗
PubMed1995

[Gene expression of human eukaryotic initiation factor-4E for protein synthesis and study of its recognition mechanism of mRNA cap structure].

Being stimulated by the insights from model studies that (i) the intimate combination of hydrogen-bonding pairing and aromatic stacking interactions is important for the specific binding of guanine base by peptide and (ii) the pi-pi stacking force of Trp is significantly strengthened by the guanine N7-methylation (m7G), this research project was started, because (a) the mRNA cap structure is characterized by the existence of m7G and (b) an eukaryotic initiation factor-4E (eIF-4E), a protein which specifically recognizes the mRNA cap structure and opens the protein biosynthesis, contains 8 Trp residues irrespective of its relatively low molecular weight of about 25 kDa. In order to prepare the sufficient amount of sample for carrying out the analysis of the recognition mechanism of mRNA cap structure by eIF-4E at the atomic level, firstly, the expression of human eIF-4E gene in Escherichia coli was attempted. An artificial gene encoding for human eIF-4E was chemically synthesized and succeeded in the expression with two different forms, i.e., as a fusion protein with human growth hormone and a direct expression of soluble protein. The isolation of eIF-4E and its purification procedure using the m7GTP affinity chromatography were accomplished. It was shown by spectroscopic methods that the recombinant eIF-4E exhibits essentially the same tertiary structure as the native one and the binding ability with mRNA cap analog was identical with each other. In order to analyze the functional amino acid residues which are essential for specific recognition of mRNA cap structure, next a series of eIF-4E mutants were prepared by the site-directed mutagenesis, and His37, His200, Trp102 and Glu103 were suggested to be important for binding of mRNA cap structure, as judged from comparison of the binding abilities of respective mutants with a m7GTP affinity column. Since the crystals of recombinant eIF-4E-m7GTP complex suitable for X-ray crystallography are now in preparation, the detailed interaction mode between them will be opened in near future.

Amino Acid Sequence↗
PubMed1995

A 3-deazauracil-resistant mutant of Bacillus subtilis with increased production of cytidine.

Bacillus subtilis No. 344 is a cytidine-producing mutant strain derived from wild type strain No. 122. When 3-deazauracil-resistant mutants were derived from strain No. 344, some of the mutants had higher productivities of cytidine. Among them, strain No. 428 accumulated 14.2 mg/ml cytidine in the culture. Cytidine 5'-triphosphate (CTP) synthetase from strain No. 428 changed to be free from feedback inhibition by CTP, compared with the enzyme from strain No. 344.

Bacillus subtilis↗
PubMed1995

Solution conformation of mu-selective dermorphin and delta-selective deltorphin-I in phospholipid micelles, studied by NMR spectroscopy and molecular dynamics simulations.

Complete proton resonance assignments of the naturally occurring mu-selective dermorphin (H-Tyr-D-Ala-Phe-Gly-Tyr-Pro-Ser-NH2) and delta-selective deltorphin-I (H-Tyr-D-Ala-Phe-Asp-Val-Val-Gly-NH2) were carried out by two-dimensional 1H-NMR techniques to investigate the conformational features in the membrane-mimetic micelles of perdeuterated dodecylphosphocholine. Fifty possible three-dimensional structures for respective peptides were generated by means of distance geometry calculations, all of which satisfy the proton-proton distances derived from NOE measurements within the allowable range, and 25 of them were subjected to the molecular dynamics simulations for 10 ps, in which the NOE distances were included as the energetic constraints. Although conformers simulated for dermorphin showed relatively large conformational variations because of the limited NOE data, most of them were characterized as an entirely folded structure bent at the Gly4 residue, where each of the N- and C-terminal tetrapeptides took an extended conformation. On the other hand, most conformations of deltorphin-I showed the common feature that the N-terminal Tyr-D-Ala-Phe-Asp and C-terminal Val-Val-Gly-NH2 sequences took respective folded conformations, and these were almost at right angles on the border of the Asp-Val sequence. These conformational characteristics are discussed in terms of the possible relationship with the mu/delta-opioid receptor selectivity.

Amino Acid Sequence↗
PubMed1995

Retinoic acid in silicone and silicone-fluorosilicone copolymer oils in a rabbit model of proliferative vitreoretinopathy.

PURPOSE: The authors evaluated the effect of retinoic acid (RA) in silicone oil (SiO) and in silicone-fluorosilicone (SiFO) copolymer oil in a new rabbit model of proliferative vitreoretinopathy (PVR). METHODS: To create the PVR model, three groups of rabbits were administered vitreous injections of approximately 100,000 homologous fibroblasts, 75,000 platelet-rich plasma (PRP), and fibroblasts + PRP, respectively. These rabbits were followed up ophthalmoscopically and histopathologically for as long as 2 months. Five additional groups of rabbits underwent gas-compression vitrectomy in one eye. Four days later, group 1 was administered intravitreous RA in SiFO (9 micrograms/ml) with approximately 150,000 fibroblasts and 70,000 PRP. Group 3 was administered the same amount of fibroblasts and PRP as group 1 with RA in SiO (9 micrograms/ml). Groups 2, 4, and 5 were administered the same amount of fibroblasts and PRP as groups 1 and 3 with 1 ml of SiFO, SiO, or balanced salt solution only, respectively. To evaluate RA toxicity, RA was injected in SiO (15 and 20 micrograms/ml) and RA in SiFO (10 micrograms/ml). RESULTS: All eyes that were administered fibroblasts or PRP developed vitreous membranes, but those with PRP alone did not develop proliferative changes or retinal detachment; fibroblasts alone produced proliferative changes and retinal detachment after 2 to 3 weeks; fibroblasts + PRP produced similar changes within 3 days of injection. Retinoic acid (15 micrograms/ml) in SiO and RA (10 micrograms/ml) in SiFO was well tolerated. Retinal atrophic changes were found in eyes with 20 micrograms/ml RA in SiO. The retinal detachment rate was lower (P < 0.05) in the eyes that were administered fibroblasts + PRP and RA than in the controls. Significant differences were found in the degrees of PVR among the groups. CONCLUSIONS: RA could be useful in PVR treated with SiO or for eyes treated intraoperatively with heavier-than-water SiFO when it is used as a short-term retinal tamponade.

Animals↗