Biomedical subjects

M Yoshimoto

Publications and source records attributed to M Yoshimoto.

At least 91 records · Page 5Linked to original sources

PubMed1999

Lewy body-type degeneration in cardiac plexus in Parkinson's and incidental Lewy body diseases.

Heart tissues of patients with PD or incidental Lewy body (LB) disease (ILBD) were examined by light and electron microscopy. LBs and alpha-synuclein-positive neurites were identified in the hearts from 9 of 11 patients with PD and from 7 of 7 patients with ILBD. LBs were present in both tyrosine hydroxylase-positive and -negative nerve processes, which are nerves of extrinsic sympathetic and intrinsic origin, respectively. These findings provide histologic evidence that the postganglionic sympathetic and intrinsic neurons in the heart are involved in the PD disease process.

Aged↗

PubMed1999

Covalent immobilization of unilamellar liposomes in gel beads for chromatography.

For immobilized (proteo)liposome chromatography, unilamellar liposomes were covalently bound within gel beads that had been activated by CNBr, N-hydroxysuccinimide, tresyl, or chloroformate. Liposomes composed of phosphatidylcholine (PC) and 2 mol% of amino-containing lipid (phosphatidylethanolamine-caproylamine) were immobilized in the activated gels at 5-35 micromol lipid/ml gel and yields of 11-70%. The highest immobilized amount was found in chloroformate-activated TSK G6000PW gel, which contains large pore size (>100 nm). Liposomes composed of PC alone could also be attached to the chloroformate-activated gels at 33-42 micromol/ml gel and yields of 58-65%, probably by crosslinking of the phosphate moiety of phospholipid with the active group of the adsorbent. Liposomes prepared by various phospholipids with or without amino-containing lipids can generally be immobilized in the chloroformate-activated gels. The covalently bound liposomes were characterized by their high stability, unilamellarity, permeability of the membranes, and drug-membrane partition properties. A stable membrane phase was constructed for chromatographic experiments to be performed under extreme elution conditions.

Chromatography, Gel↗

PubMed1999

Dynamic changes in glucose metabolism induced by thiamine deficiency and its replenishment as revealed by a positron autoradiography technique using rat living brain slices.

Dynamic changes in the cerebral glucose metabolic rate (CMRglc) before and after thiamine replenishment were investigated in living brain slices obtained from pyrithiamine-treated (PT) and pair-fed control rats by use of a positron autoradiography technique. Fresh rat brain slices (300 microm thick) were incubated with [18F]2-fluoro-2-deoxy-D-glucose ([18F]FDG) in oxygenated Krebs-Ringer solution at 36 degrees C, during which serial two-dimensional images of [18F]FDG uptake in the slices were constructed on the imaging plates. The net influx constant (=K) of [18F]FDG was determined by a Patlak graphical method of the image data. Prior to thiamine pyrophosphate (TPP)-loading, the K value in the neurologically symptomatic PT was higher in all brain regions except the thalamus and mammillary body than the control, suggesting compensatory enhanced glycolysis. The rapid decrease in this heightened net influx constant immediately after TPP-loading was surmised to be due to activation of pyruvate oxidation with lactate as the substrate, with this inhibiting the glycolysis. From > or = 150 min after TPP-loading, the K value continued to show low values in the thalamus and mammillary body, which are regarded as the responsible sites for Korsakoff syndrome, whereas in all other sites recovery to control values was observed. These findings suggest that using this technique the quantitative evaluation of serial local changes in CMRglc from thiamine deficiency to after its replenishment may be useful in elucidating the pathophysiology and prognosis of Wernicke's encephalopathy.

Animals↗

PubMed1999

Localization of a tumor suppressor gene associated with the progression of human breast carcinoma within a 1-cM interval of 8p22-p23.1.

BACKGROUND: Frequent allelic losses on the short arm of chromosome 8 in several types of human cancers, and deletion maps of this region in tumor DNAs, have suggested that 8p harbors one or more genes that are important for suppressing tumorigenesis in the tissues in question. METHODS: To define the locations of potential tumor suppressor genes involved in breast carcinoma, the authors examined 144 primary breast carcinomas for loss of heterozygosity at 18 highly polymorphic microsatellite loci on 8p. They also sought correlations between allelic loss on 8p and several clinicopathologic parameters. RESULTS: Allelic loss was observed in 74 of the 144 sporadic breast carcinomas examined. Whereas more than half of the informative tumors showed loss of an allele at every locus on the short arm, 32 showed partial or interstitial deletions. Deletion mapping in this panel of tumors identified two distinct commonly deleted regions, one in a 1-cM interval flanked by D8S511 and D8S1991 at 8p22-p23.1, and the other in a 16-cM interval flanked by D8S136 and D8S1477 at 8p22-p21. Allelic losses in both of these regions were observed more frequently in tumors of the solid-tubular or scirrhous type than in less aggressive histologic types. Furthermore, allelic loss in either region occurred more frequently in larger and infiltrative tumors (T1 < T2 < T3). CONCLUSIONS: The association of allelic losses on 8p with advanced tumor stage and aggressive histologic type implies that loss or inactivation of one of at least two putative tumor suppressor genes on 8p may contribute to the progression of breast carcinoma.

Breast Neoplasms↗

PubMed1999

Dynamic changes in glucose metabolism of living rat brain slices induced by hypoxia and neurotoxic chemical-loading revealed by positron autoradiography.

Fresh rat brain slices were incubated with 2-deoxy-2-[18F]-fluoro-D-glucose ([18F]FDG) in oxygenated Krebs-Ringer solution at 36 degrees C, and serial two-dimensional time-resolved images of [18F]FDG uptake were obtained from these specimens on imaging plates. The fractional rate constant (= k3*) of [18F]FDG proportional to the cerebral glucose metabolic rate (CMRglc) was evaluated by applying the Gjedde-Patlak graphical method to the image data. With hypoxia loading (oxygen deprivation) or glucose metabolism inhibitors acting on oxidative phosphorylation, the k3* value increased dramatically suggesting enhanced glycolysis. After relieving hypoxia < or = 10-min, the k3* value returned to the pre-loading level. In contrast, with > or = 20-min hypoxia only partial or no recovery was observed, indicating that irreversible neuronal damage had been induced. However, after loading with tetrodotoxin (TTX), the k3* value also decreased but returned to the pre-loading level even after 70-min TTX-loading, reflecting a transient inhibition of neuronal activity. This technique provides a new means of quantifying dynamic changes in the regional CMRglc in living brain slices in response to various interventions such as hypoxia and neurotoxic chemical-loading as well as determining the viability and prognosis of brain tissues.

Animals↗

PubMed1999

MYCN gene amplification. Identification of cell populations containing double minutes and homogeneously staining regions in neuroblastoma tumors.

Neuroblastoma is the second most common solid tumor occurring in children. Amplification of the MYCN oncogene is associated with poor prognosis. To identify neuroblastoma tumors with MYCN amplification, we studied the number of copies of MYCN in interphase cells by fluorescence in situ hybridization in 20 neuroblastoma patients. MYCN amplification appeared in 7 tumor specimens. Interphase and metaphase studies showed a tumor cell population with both forms of amplification, double minutes and homogeneously staining regions, in two patients. These patients showed a smaller tumor cell subpopulation with the presence of more than one homogeneously staining region, suggesting that gene amplification was undergoing karyotype evolution.

Adolescent↗

PubMed1999

The effects of benzodiazepine (triazolam), cyclopyrrolone (zopiclone) and imidazopyridine (zolpidem) hypnotics on the frequency of hippocampal theta activity and sleep structure in rats.

In order to investigate the relative efficacy and safety of zopiclone and zolpidem, we compared the effects of higher doses of zopiclone and zolpidem on the frequency of hippocampal theta activity and sleep structure with that of triazolam. Rats were divided into triazolam treatment group (1 mg/kg, 5 mg/kg), zopiclone treatment group (20 mg/kg, 100 mg/kg) and zolpidem treatment group (20 mg/kg, 100 mg/kg). Rats were injected intraperitoneally with these drugs or their vehicle. Polygraphic sleep recording and visual frequency analysis of the hippocampal EEG activity in REM sleep were carried out for 6 h after each injection. Zolpidem, unlike triazolam and zopiclone, had a much milder reducing-effect on the frequency of hippocampal theta activity and suppressing-effect on REM sleep. These results suggest that zolpidem may prove to be a safer hypnotic drug which has fewer or milder side effects than are benzodiazepine and cyclopyrrolone hypnotics.

Animals↗

PubMed1999

Different effects of L-type and T-type calcium channel blockers on the hypnotic potency of triazolam and zolpidem in rats.

We examined the effects of an L-type Ca2+ channel blocker, nilvadipine (0.5 and 2.0 mg/kg), and that of a T-type Ca2+ channel blocker, flunarizine (10.0 and 40.0 mg/kg), on the hypnotic potency of both a benzodiazepine (BZ)-hypnotic, triazolam (1.0 mg/kg), and a non-BZ hypnotic, zolpidem (20.0 mg/kg), in rats. The polysomnogram was recorded for 6 h after administration of the vehicle solution alone, or after one of the Ca2+ channel blockers, with or without one of the hypnotics. Both Ca2+ channel blockers prolonged the increased total time of non-rapid eye movement (non-REM) sleep induced by either hypnotic. In the case of triazolam, however, the non-REM sleep-enhancing effect induced by nilvadipine was greater than that induced by flunarizine. These findings indicate that the hypnotic action of triazolam is potentiated more strongly by an L-type Ca2+ channel blocker than by a T-type Ca2+ channel blocker.

Animals↗

PubMed1999

Oxidative refolding of Denatured/Reduced lysozyme utilizing the chaperone-like function of liposomes and immobilized liposome chromatography

Oxidative refolding of the denatured/reduced lysozyme was examined in the presence of small unilamellar vesicles (SUVs) essentially composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC). SUVs facilitated the recovery of the enzymatic activity of lysozyme like molecular chaperones through the interaction with the refolding intermediate of lysozyme. The highest reactivation yield (87%) was obtained by delaying oxidation time (15-30 s) after dilution of the denaturant concentration was initiated in the presence of SUVs. SUVs supplemented with 1 mol % phosphatidylethanolamine were covalently coupled to gel beads, and then the interactions of SUVs with lysozyme at the various conformations were quantitatively examined with immobilized liposome chromatography (ILC). The reduced lysozyme lacking disulfide bonds was found to have a property similar to that of the molten globule state in terms of its local hydrophobicity, which was determined with the aqueous two-phase partitioning method. The reduced lysozyme was more clearly retarded on the ILC column than the native and 1 M guanidinium hydrochloride (GuHCl)-treated lysozymes with intact disulfide bonds. Similar results were obtained for alpha-lactalbumin, which has three-dimensional structure closely similar to that of lysozyme, regarding the membrane-protein interaction. These results can be interpreted as follows. In the early stage of the oxidative refolding, liposomes bound to the refolding intermediate of lysozyme lacking disulfide bonds. Then, liposomes assisted the formation of the tertiary structure of lysozyme by reducing protein intermolecular interactions, which usually cause the formation of the inactive aggregates. Consequently, the correct formation of the disulfide bonds was promoted. On the basis of the above results, the chromatographic oxidative refolding was also examined with ILC. The denatured/reduced lysozyme (9 mg/mL, 10 &mgr;L) was passed through the ILC column with a flow rate of 1 mL/min, which corresponds to the retention of lysozyme about 1 min in the ILC column. Subsequent oxidation of the eluted lysozyme resulted in the almost complete recovery (100%) of the original enzymatic activity of lysozyme.

Journal Article↗

PubMed1999

Delay in administration of CDDP until completion of AGM-1470 treatment enhances antimetastatic and antitumor effects.

The efficacy of cis-diammine dichloroplatinum (CDDP) therapy in combination with continuous administration of angiogenesis inhibitor o-(chloroacetyl-carbamoyl) fumagillol (AGM-1470) was evaluated experimentally using a transplantable rat osteosarcoma line previously established in our laboratory. AGM-1470 (2.5 mg/kg body weight/week) was administered by Alzet osmotic pumps for 2 weeks starting from 7 days after tumor inplantation and CDDP (1.25 mg/kg) was given on days 21 and 24. The number of lung metastatic nodules was counted and the wet weights of the primary tumors were measured 5 weeks after tumor inplantation. Values with administration of CDDP 3 days after discontinuation of AGM-1470 were significantly lower than when the two agents were coadministered (P < 0.05). This animal model should facilitate optimization of the timing of combination therapy.

Animals↗

PubMed1999

Mutations in intron 3 of GH-1 gene associated with isolated GH deficiency type II in three Japanese families.

OBJECTIVE: Isolated GH deficiency (IGHD) type II is a disorder inherited in an autosomal dominant manner. Three mutations at the donor splice site of intron 3 of the GH-I gene have been identified in five families. In this report, we describe a novel mutation also at the donor splice site of intron 3 in patients with IGHD type II. PATIENTS: Five individuals diagnosed as IGHD: two sporadic cases and one family with three affected individuals (two siblings and their father). MEASUREMENT: Genomic DNA was extracted from peripheral mononuclear cells. All the exons and introns of the GH-I gene were amplified by polymerase chain reaction (PCR) and subjected to sequence analysis. RESULTS: A guanine to adenine transition at the fifth base of intron 3 (mutE), which has not been reported, was identified in the familial case but not in unaffected members of the family including the paternal grandparents. In the other two families with sporadic cases, a guanine to adenine transition at the first base of intron 3 (mutA) was identified in the affected subjects but not in other members of the families. CONCLUSION: MutE has not been previously reported and is the fourth mutation associated with IGHD type II. The guanine residue mutated in mutA was the second nucleotide of a CpG dinucleotide, which is regarded as a hot spot for mutations by a methylation-deamination mechanism. Since mutA has previously been identified in three type II IGHD kindreds belonging to different ethnic backgrounds, this appears to be the most frequent GH-I gene mutation in IGHD with a dominant inheritance. Because de novo mutations appeared to have occurred in all three families analyzed in the present study and the presence or absence of these mutations can easily be tested by PCR and restriction enzyme digestion, not only the familial cases but also sporadic cases with IGHD should be examined for a possible mutation at the donor splice site of intron 3 in the GH-1 gene.

Adolescent↗

PubMed1999

Widespread occurrence of alpha-synuclein/NACP-immunoreactive neuronal inclusions in juvenile and adult-onset Hallervorden-Spatz disease with Lewy bodies.

Alpha-Synuclein (originally called precursor of the non-Abeta component of Alzheimer's disease amyloid-NACP) is a presynaptic nerve terminal protein and is now known to be a major component of Lewy bodies (LBs) in Parkinson's disease. Previous studies have shown that LBs are occasionally found in patients with Hallervorden-Spatz disease (HSD), a hereditary or sporadic neuroaxonal dystrophy. Therefore, an immunocytochemical examination of the brain tissues from two patients with HSD for alpha-synuclein/NACP was performed. In both cases, LBs were observed in the substantia nigra, locus ceruleus and other subcortical nuclei. These LBs were strongly immunolabelled with anti-alpha-synuclein/NACP. Moreover, abnormal alpha-synuclein/NACP-immunoreactive structures in the neuronal somata and processes were found in the cerebral neocortex, hippocampus, basal ganglia, thalamus, pontine and inferior olivary nuclei, spinal grey matter, and peripheral sympathetic ganglia. Although numerous dystrophic axons (spheroids) were found throughout the brain, either none or only a few were positive for alpha-synuclein/NACP. These findings suggest that widespread accumulation of alpha-synuclein/NACP is a pathological feature in patients suffering from HSD with LBs, and that this phenomenon is unrelated to axonal spheroid formation.

Adult↗

PubMed1999

Panic attacks in patients with chronic schizophrenia: a complication of long-term neuroleptic treatment.

Panic attacks meeting the diagnostic criteria for panic disorder (DSM-III-R) were found in nine (20%) of 45 patients suffering chronic schizophrenia for more than 5 years. The scores of the Hamilton Depression Rating Scale and the Simpson Angus Scale were significantly higher in the group of patients with panic attacks. They also tended to be taking neuroleptics in larger doses than in the other group. The present report suggests that long-term treatment with neuroleptics is closely related to the manifestation of panic attacks in chronic schizophrenia. It also suggests that when panic attacks are seen frequently in patients taking high doses of neuroleptics, dose reduction of neuroleptics should be considered.

Adult↗

PubMed1999

Expression of matrix metalloproteinase 2 (MMP-2), membrane-type 1 MMP and tissue inhibitor of metalloproteinase 2 and activation of proMMP-2 in pancreatic duct adenocarcinomas in hamsters treated with N-nitrosobis(2-oxopropyl)amine.

In order to assess the significance of changes in metalloproteinase activity in pancreatic carcinogenesis, the expression of matrix metalloproteinases 2 and 9 (MMP-2 and MMP-9, respectively), tissue inhibitor of metalloproteinase-1 (TIMP-1) and TIMP-2, and membrane-type 1 MMP (MT1-MMP) and MT2-MMP in ductal lesions in a rapid-production model for pancreatic duct carcinomas (PCs) in hamsters initiated with N-nitrosobis(2-oxopropyl)amine (BOP) and in subcutaneous transplantable tumors of hamster pancreatic duct carcinoma (HPDs) was investigated. Northern analysis revealed MMP-2, MMP-9, TIMP-2 and MT1-MMP mRNAs to be overexpressed in PCs. Immunohistochemically, elevated levels of MMP-2 were apparent in early duct epithelial hyperplasias and staining increased from atypical hyperplasias to carcinomas. Gelatin zymography demonstrated clear activation of proMMP-2 but not proMMP-9 in both of primary and HPD tumors, the MT1-MMP mRNA level and proMMP-2 activation being significantly correlated (r = 0.893, P < 0.001). In our rapid production model, 0.1 and 0.2% OPB-3206, an inhibitor of MMPs, given in the diet after two cycles of augmentation pressures for 48 days decreased the incidence and number of carcinomas. Gelatin zymography demonstrated that OPB-3206 inhibited activation of proMMP-2 in pancreatic cancer tissues. These results indicate that overexpression of MMP-2, TIMP-2 and MT1-MMP, and cell surface activation of proMMP-2 by MT1-MMP, are involved in the development of PCs, and that MMP-2 expression at the protein level appears in the early phase of pancreatic duct carcinogenesis. OPB-3206 may be a candidate chemopreventive agent for pancreatic ductal adenocarcinomas.

Adenocarcinoma↗

PubMed1999

The location of positive nodes partly influences the prognostic value of the number of positive nodes in breast cancer patients.

BACKGROUND: The aim was to determine whether the number of positive lymph nodes or the location of lymph node metastasis (location number) would permit a more accurate prediction of prognoses. METHODS: We compared the survival rates of 3922 patients with primary breast cancer in relation to the location number and the number of positive lymph nodes. Survival rates were calculated by the Kaplan-Meier method and analyzed using the log rank test. RESULTS: Within the n1 alpha group, the presence of one or two positive nodes was associated with significantly better survival than the presence of three positive nodes. These groups should therefore be distinguished. Within the n1 beta group, there was no significant difference in survival between patients with four and those with seven or more positive nodes. Comparisons of n1 beta and n2 patients after subgrouping by the number of positive nodes (4-9 and 10 or more) revealed a significantly poorer prognosis in the n2 group. CONCLUSIONS: When the prognosis of breast cancer is considered from the viewpoint of lymph node metastasis, the location number as described in the General Rules is an excellent classification. However, we should be aware of possible differences in the prognosis depending on the number of positive nodes, as this is masked by the location number.

Adult↗

PubMed1999

Different brain morphologies from different genotypes in a single teleost species, the medaka (Oryzias latipes)

In a teleost fish, the medaka (Oryzias latipes), many inbred strains have been established from various origins including wild populations. Brains from five genetically different strains, which had been bred and raised under the same conditions, were examined to determine whether there is intraspecific genetic variation. A total of 25 brains from the wild-type strains (HNI-II, HB11A and HB32C) and from the body-colour mutant strains (Hi3 and HO5) were fixed, and the external features of the brains were examined under a stereomicroscope. The differences between the HNI-II brains and the Hi3 brains were the most remarkable in the external features. In order to carry out a volumetric analysis, the brains of all strains were cut into complete serial cryostat sections. Total brain volumes and relative volumes (in % of total brain volume) of the olfactory bulb, telencephalon, optic tectum, and cerebellum were calculated in each brain using a semi-automatic image analyzer. Statistical analysis showed that significant differences in the total brain volumes and the relative volumes of these subdivisions exist not only between wild-type and mutant strains but also among wild-type strains. Thus, our results demonstrate that the strains with different genotypes possess large variation in brain morphology. This is the first report to demonstrate that there exists intraspecific genetic variation in the gross brain morphology of a wild-type vertebrate.

Animals↗

PubMed1999

Tectal fiber connections in a non-teleost actinopterygian fish, the sturgeon Acipenser.

Tectal fiber connections were studied in members of an early branch of the actinopterygian lineage, the sturgeons Acipenser transmontanus and A. schrenkii, by means of biocytin, HRP, biotinylated dextran amine, and DiI tract tracing methods. The aim of this study is to elucidate the visual pathway via the optic tectum to the thalamus as a part of a series of studies on the visual pathways in sturgeons. After biocytin or biotinylated dextran amine injections to the optic tectum terminals are found bilaterally in the medial and lateral portions of both the dorsal thalamus and ventral thalamus. Ipsilateral projections are much more abundant. Tectal recipient areas in the thalamus overlap in part with the retinal recipient areas. After HRP or DiI injections to the dorsal or ventral thalamus, tectal neurons projecting to the thalamus were labeled in the ipsilateral or bilateral stratum periventriculare. Dendritic morphology of tectothalamic neurons suggests that they receive direct retinal input. These results suggest that visual information passes through the tectum to the thalamic areas which also receive direct retinal projections. In this regard, the visual system of Acipenser resembles that of chondrichthyans (sharks). Other fiber connections of the tectum are also described, which have not previously been studied by tracer methods in a sturgeon.

Animals↗

PubMed1999

Visual thalamotelencephalic pathways in the sturgeon Acipenser, a non-teleost actinopterygian fish.

Terrestrial vertebrates (amphibians, reptiles, birds, and mammals) possess two visual systems, the geniculate and extrageniculate pathways to the telencephalon. In cartilaginous fishes (e.g. sharks) both retinal and tectal neurons project to neurons in the thalamus, which themselves project to a single area in the telencephalon. The condition in ray-finned fishes (Actinopterygii) is ambiguous. In many teleosts there is a well developed extrageniculate pathway but no obvious geniculate system. This study reports on the thalamotelencephalic projections of a sturgeon, a non-teleost ray-finned fish. Several tract tracing methods (e.g., HRP, WGA-HRP, biocytin, BDA, DiI) were employed in conjunction with normal techniques for identifying neural structures (e.g., Nissl, Golgi). After injections of tracer into retinal and tectal recipient areas of the thalamus, labeled terminals were observed in the ventrolateral region of the caudal telencephalon, an area referred to as the thalamic projection area. After injections of tracer into the telencephalon, populations of retrogradely filled neurons were located in both the dorsal and ventral thalamus. These data demonstrate that thalamic neurons in both retinal and tectal pathways project directly to the telencephalon. These results support the view that two visual pathways are a primitive feature of vertebrate brain organization. These results are also consistent with the hypothesis that the ancestor of Acipenser and Teleostei (Actinopteri) acquired a novel visual pathway to the telencephalon through the ventral portion of the thalamus.

Animals↗