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Biomedical subjects

T Miki

Publications and source records attributed to T Miki.

At least 127 records · Page 7Linked to original sources
PubMed2000

Frequency of choroidal abnormalities in neurofibromatosis type 1.

BACKGROUND: Choroidal neurofibromatosis is thought to be a rare form of neurofibromatosis that involves the eyes. The development of infrared light examination with a scanning laser ophthalmoscope (SLO) and indocyanine-green fundus angiography has allowed examination of the choroid. We studied choroidal abnormalities in patients with neurofibromatosis 1 and compared their frequency with that of other ocular abnormalities. METHODS: We examined 33 eyes of 17 consecutive patients diagnosed with neurofibromatosis 1 by conventional ophthalmoscopy and by non-invasive infrared monochromatic light with confocal SLO. 76 eyes of 39 age-matched controls were examined similarly by confocal SLO. 21 digital fluorescein and indocyanine-green angiographies were obtained from 11 adult patients, and 77 angiograms were obtained from age-matched controls. FINDINGS: Infrared monochromatic light examination by confocal SLO showed bright multiple patchy regions at and around the entire posterior pole of all 33 eyes examined. All bright patchy regions seen in adult patients corresponded to hypofluorescent areas on their indocyanine-green angiograms. However, no abnormalities were noted in any patient at corresponding areas under conventional ophthalmoscopic examination or fluorescein angiography. In SLO and indocyanine-green studies, controls and control angiograms showed no choroidal abnormalities. Iris nodules were noted in 25 eyes (76%) of 14 patients (82%) and eyelid neurofibroma in five patients (29%). INTERPRETATION: The bright patchy regions noted under infrared fundus examination and the corresponding hypofluorescent areas seen on indocyanine-green angiograms are probably of choroidal origin. The high frequency (100%) of these abnormalities suggests that the choroid is one of the structures most commonly affected by neurofibromatosis 1.

Adult↗
PubMed2000

Cardioprotective mechanism of ischemic preconditioning is impaired by postinfarct ventricular remodeling through angiotensin II type 1 receptor activation.

BACKGROUND: Activation of protein kinase C-linked receptors and subsequent opening of the mitochondrial ATP-sensitive K(+) (mitoK(ATP)) channel are crucial in preconditioning (PC). This study examined whether postinfarct ventricular remodeling interferes with the PC mechanism. METHODS AND RESULTS: Two weeks before isolation of hearts, rabbits underwent a sham operation or coronary ligation (COL) to induce remodeling. Isolated buffer-perfused hearts were subjected to 30-minute global ischemia/2-hour reperfusion, and infarct size was expressed as a percentage of the left ventricle (%I/LV), from which the scarred infarct by COL was excluded. Although %I/LV was similar in sham-operated and remodeled hearts (52.9+/-6.5% versus 45.8+/-5.2%), PC with 2 episodes of 5-minute ischemia protected sham-operated but not remodeled hearts (%I/LV=18.1+/-2.5% versus 54.8+/-2.9%, P<0.05). Infusion of valsartan (10 mg x kg(-1). d(-1), an angiotensin II type 1 (AT(1)) receptor blocker, for 2 weeks after COL prevented the ventricular remodeling and preserved the response to PC (%I/LV=27.4+/-3.8%), although valsartan alone did not change %I/LV. Diazoxide, a mitoK(ATP) channel opener, protected both sham-operated and remodeled hearts (%I/LV=14.1+/-3.1% and 8.3+/-3.6%). CONCLUSIONS: The myocardium remodeled after infarction is refractory to PC, which is probably due to interruption of cellular signaling by PC upstream of mitoK(ATP) channels. An AT(1) receptor blocker is beneficial not only for suppression of ventricular remodeling but also for preservation of the PC mechanism.

Angiotensin II↗
PubMed2000

Deficiency in mitochondrial aldehyde dehydrogenase increases the risk for late-onset Alzheimer's disease in the Japanese population.

Mitochondrial aldehyde dehydrogenase 2 (ALDH2) deficiency is caused by a mutant allele in the Mongoloids. To examine whether genetic constitutions affecting aldehyde metabolism influence the risk for late-onset Alzheimer's disease (LOAD), we performed a case-control study in the Japanese population on the deficiency in ALDH2 caused by the dominant-negative mutant allele of the ALDH2 gene (ALDH2*2). In a comparison of 447 patients with sex, age, and region matched nondemented controls, the genotype frequency carrying the ALDH2*2 allele was significantly higher in the patients than in the controls (48.1% vs 37.4%, P = 0.001). Logistic regression analysis indicates that carriage of the ALDH2*2 allele is an independent risk for LOAD of the epsilon4 allele of the apolipoprotein E gene (APOE-epsilon4) (P = 0.002). Moreover, the odds ratio for LOAD in carriers of the ALDH2*2 allele was almost twice that in noncarriers, irrespective of status with regard to the APOE-epsilon4 allele. Among patients homozygous for the APOE-epsilon4 allele, age at onset of LOAD was significantly lower in those with than without the ALDH2*2 allele. In addition, dosage of the ALDH2*2 allele significantly affected age at onset of patients homozygous for the APOE-epsilon4 allele. These results indicate that the ALDH2 deficiency is a risk for LOAD, synergistically acting with the APOE-epsilon4 allele.

Age of Onset↗
PubMed2000

MTABC3, a novel mitochondrial ATP-binding cassette protein involved in iron homeostasis.

Atm1p, a mitochondrial half-type ATP-binding cassette (ABC) protein in Saccharomyces cerevisiae, transports a precursor of the iron-sulfur (Fe/S) cluster from mitochondria to the cytosol. We have identified a novel half-type human ABC protein, designating it MTABC3 (mammalian mitochondrial ABC protein 3). MTABC3 mRNA is ubiquitously expressed in all of the rat and human tissues examined. MTABC3 protein is shown to be present in the mitochondria, as assessed by immunoblot analysis and confocal microscopic analysis of subcellular fractions of Chinese hamster ovary cells stably expressing MTABC3. Accumulation of iron in the mitochondria, mitochondrial DNA damage, and respiratory dysfunction in the yeast ATM1 mutant strain (atm1-1 mutant cells) were almost fully reversed by expressing MTABC3 in these mutant cells. These results indicate that MTABC3 is a novel ortholog of the yeast and suggest an important role in mitochondrial function. Interestingly, the human MTABC3 gene has been mapped to chromosome 2q36, a region within the candidate locus for lethal neonatal metabolic syndrome, a disorder of the mitochondrial function associated with iron metabolism, indicating that MTABC3 is a candidate gene for this disorder.

ATP-Binding Cassette Transporters↗
PubMed2000

Accumulation of GTP-bound RhoA during cytokinesis and a critical role of ECT2 in this accumulation.

We developed a new pull-down assay for GTP-Rho and examined its level during cell cycle. HeLa cells were arrested in the S phase by thymidine and were enriched in the prometaphase, metaphase, telophase, and G(1) phase by collecting at 0, 45, 90, and 180 min after the release from the nocodazole arrest, respectively. The level of GTP-Rho did not change significantly from the S phase to the prometaphase, but increased thereafter, peaking in the telophase, and returned to the original level in the G(1) phase. The GDP-GTP exchange activity for Rho measured in cell lysates in parallel increased also during the mitosis with a peak in the metaphase. Using this system, we examined a role of ECT2, an exchanger for Rho GTPases, suggested to be involved in cytokinesis (Tatsumoto, T., Xie, X., Blumenthal, R., Okamoto, I., and Miki., T. (1999) J. Cell. Biol. , 147, 921-928). Expression of the dominant negative form of ECT2 completely suppressed both the rise of GTP-Rho in the telophase and the increased GDP-GTP exchange activity in the mitotic cell extracts. These results suggest a critical role of ECT2 in Rho activation during cytokinesis.

Animals↗
PubMed2000

Prenatal X-irradiation increases GFAP- and calbindin D28k-immunoreactivity in the medial subdivision of the nucleus of solitary tract in the rat.

Glial fibrillary acidic protein- (GFAP) and calbindin D28k-immunoreactivity (IR) were investigated in the medial subdivision of the nucleus of the solitary tract (mNST) of prenatally X-irradiated rats. Pregnant rats were exposed to a single whole-body X-irradiation on day 11 or 16 of gestation at a dose of 1. 3 Gy. The offspring were killed at 7-14 days of age for the immunohistochemical observations. Rat pups showed strong GFAP-IR at the level rostral to the obex when receiving X-rays on day 11 of gestation, with hypertrophy of astrocyte cell bodies and cytoplasmic processes, but weak GFAP-IR when receiving X-rays on day 16 of gestation. Calbindin D28k-IR was stronger in the animals receiving X-rays on day 11 or 16 of gestation compared to that in the control animals. In the present study, the increase of GFAP- and calbindin D28k-IR cells in the mNST might indicate that adaptative mechanisms are taking place to preserve integrated nervous system function and possibly, to provide neuroprotection.

Adaptation, Physiological↗
PubMed2000

Linkage of human narcolepsy with HLA association to chromosome 4p13-q21.

Although narcolepsy is highly associated with human leukocyte antigen (HLA) DQ6/DQB1*0602 and/or DR2/DRB1*1501, most individuals with the HLA haplotype are free of narcolepsy. This indicates that HLA alone makes a relatively small contribution to the development of narcolepsy and that a non-HLA gene(s) can contribute to the genetic predisposition even in narcoleptic cases with HLA association. We conducted a genome-wide linkage search for narcolepsy in eight Japanese families with 21 DR2-positive patients (14 narcoleptic cases with cataplexy and 7 cases with an incomplete form of narcolepsy). A lod score of 3.09 suggested linkage to chromosome 4p13-q21. A lod score of 1.53 was obtained at the HLA-DRB1 locus, though this lod score may be biased since all the affected patients and many of the family members were DR2-positive. No other loci including hypocretin, hypocretin receptor 1, and hypocretin receptor 2 had lod scores greater than 1.0. The present study suggests that chromosome 4p13-q21 contains a second locus for HLA-associated human narcolepsy.

Chromosome Mapping↗
PubMed2000

Prostate-specific transcription factor hPSE is translated only in normal prostate epithelial cells.

We recently cloned a novel transcription factor gene, hPSE, which belongs to the Ets gene family. hPSE mRNA was expressed specifically in prostate glandular epithelial cells and also in the human prostate carcinoma cell lines PC-3 and LNCaP. On the other hand, on immunoblot analysis with anti-hPSE antiserum, hPSE protein was detected only in human prostate tissue samples and not in PC-3 or LNCaP culture cells. Immunohistochemistry and in situ hybridization analysis revealed that hPSE protein was translated in normal prostate glandular epithelial cells, but not in carcinoma cells with hPSE transcripts. These findings suggest that expression of hPSE is regulated translationally in prostate epithelial cells and that hPSE protein is a candidate for a marker distinguishing normal cells from cancer cells in the prostate. It appeared that the 5'- and 3'-untranslated regions of hPSE transcripts might be necessary for translational control of hPSE, on the basis of results of transfection analysis in non-prostate lineage cells (HEK-293) using some deletion mutants of hPSE cDNA.

Cell Transformation, Neoplastic↗
PubMed2000

Selective photodynamic effects of the new photosensitizer ATX-S10(Na) on choroidal neovascularization in monkeys.

OBJECTIVE: To determine the optimal treatment variables for photodynamic therapy (PDT) with new photosensitizer ATX-S10(Na) (13,17-bis[1-carboxypropionyl] carbamoylethyl-8-etheny-2-hydroxy-3-hydroxyiminoethyliden e-2,7,12,18-tetranethyl 6 porphyrin sodium) to induce selective occlusion of choroidal neovascularization (CNV) in nonhuman primate eyes. METHODS: Experimental CNV was induced in monkey eyes by laser photocoagulation, and PDT was performed in neovascularized and healthy eyes with different treatment variables. At 0 to 150 minutes after 4-, 8-, and 12-mg/kg of body weight intravenous injections of ATX-S10(Na), a diode laser was irradiated at the dose of 1 to 127 J/cm2 (wavelength, 670 nm). Vascular occlusion induced by PDT was evaluated using fluorescein angiography, indocyanine green angiography, and histological examination at 1 day to 4 weeks after irradiation. RESULTS: Selective occlusion of CNV without damage to healthy retinal and choroidal capillaries was achieved in the following conditions: 30 to 74 J/cm2 irradiation at 30 to 74 minutes after the 8-mg/kg injection, and 1 to 29 J/cm2 irradiation at 30 to 74 minutes or 30 to 74 J/cm2 irradiation at 75 to 150 minutes after the 12-mg/kg dye injection. Regrowth of CNV often occurred when the retina was heavily injured by excessive PDT. CONCLUSION: By using optimal treatment variables, PDT using ATX-S10(Na) induces selective occlusion of CNV in nonhuman primate eyes, providing the possibility of therapeutic application to the clinical practice. CLINICAL RELEVANCE: Occlusion of CNV without direct damage to the sensory retina is useful to preserve visual acuity in patients with exudative age-related macular degeneration. A clinical trial of PDT using ATX-S10(Na) is desirable.

Animals↗
PubMed2000

Long-term effectiveness of photodynamic therapy by using a hydrophilic photosensitizer ATX-S10(Na) against experimental choroidal neovascularization in rats.

BACKGROUND AND OBJECTIVE: We previously demonstrated that a hydrophilic photosensitizer ATX-S10 had a potent photodynamic effect. This study was designed to reveal the long-term effectiveness of photodynamic therapy (PDT) with this agent in occluding choroidal neovascularization (CNV) and its selectivity in the neovascular tissue. STUDY DESIGN/MATERIALS AND METHODS: Experimental CNV was induced by intense photocoagulation in rat eyes. Immediately or 2 hours after intravenous injection of 8 mg/kg body weight of ATX-S10(Na), a cis isomer of ATX-S10, eyes were irradiated by a diode laser at the radiance of 3.25-65.3 J/cm(2) Vascular occlusion was identified by fundus photography, fluorescein angiography, and histology at 1, 3, 7, 14, and 28 days after PDT. As controls, non-neovascular eyes were subjected to PDT and similarly analyzed. RESULTS: By using the following treatment parameters, PDT with ATX-S10(Na) successfully occluded CNV without causing occlusion of retinal capillaries for 28 days; 7.4 and 19.6 J/cm(2) immediately after dye injection and 36.7 and 65.3 J/cm(2) 2 hours after injection. Although these conditions also caused occlusion of normal choriocapillaries and mild injuries of retinal vessels, retinal pigment epithelium, and photoreceptors at 1 day, retinal vessels and pigment epithelial cells recovered from damages by 28 days. No injuries were found in the inner retina. CONCLUSION: In optimal treatment conditions, PDT with ATX-S10(Na) can induce long-term, selective occlusion of CNV without causing irreversible damages in the inner retina.

Animals↗
PubMed2000

Characterization of complex chromosomal abnormalities in B-cell lymphoma by a combined spectral karyotyping (SKY) analysis and fluorescence in situ hybridization (FISH) using a 14q telomere probe.

We report a case of non-Hodgkin's lymphoma of unknown origin with invasion into bone marrow and brain. This case showed complex chromosomal abnormalities, including five clonal marker chromosomes (mar) and four additional materials of unknown origin (add) that could not be identified by means of conventional G-banding. Spectral karyotyping (SKY) analysis could not only determine the origin and organization of all thus far unidentified structural chromosomal abnormalities but also detect two cryptic unbalanced translocations, which had been erroneously considered to be normal on the basis of G-banding analysis, and correct one abnormality misidentified by G banding. Among these abnormalities, we identified the new partner site of the 14q32 translocation, 22q13, and the jumping translocations involving 2p23 as a new donor chromosome. Furthermore, by using fluorescence in situ hybridization (FISH) with the probes specific for the 14q telomere, we could identify the unbalanced translocation of t(3;14)(q27;q32), which had been erroneously considered to be normal chromosome 3 on the basis of not only G-banding but also of SKY analysis. This translocation is one of the most frequent chromosomal abnormalities in B-cell lymphoma, especially diffuse large cell lymphoma. After SKY and FISH analysis, the original descriptions in the G-band karyotype were modified for a total of 13 chromosomes. The combination of SKY and FISH using the 14q telomere probe was therefore considered very useful for the characterization of complex cytogenetic cases in B-cell lymphoma.

Chromosome Aberrations↗
PubMed2000

Inadvertent corneal burn by using indirect wide-field contact lenses and different laser beam delivery systems during experimental fundus photocoagulation.

BACKGROUND AND OBJECTIVE: At fundus photocoagulation by using a wide-field indirect contact lens, the laser radiant exposure may be increased at the anterior segment of the eye. We examined the likelihood of producing inadvertent corneal burn by using parfocal and sharped edge defocus laser delivery systems with various indirect contact lenses. STUDY DESIGN/MATERIALS AND METHODS: The two laser delivery systems were used with four lenses of different viewing angles during fundus photocoagulation in a total 44 eyes of rabbits. RESULTS: By using the lenses, the parfocal system increased corneal radiant exposure more than did the sharped edge defocus system. By using the Widefield PRP 165 lens of the widest viewing angle, there was no difference between the two systems in the corneal burns produced. CONCLUSION: Some indirect contact lenses used in combination with the parfocal system caused inadvertent corneal burns more readily than did the same lenses in combination with the sharped edge defocus system.

Animals↗
PubMed2000

Neurons in the hilus region of the rat hippocampus are depleted in number by exposure to alcohol during early postnatal life.

We have previously shown that exposing rats to a relatively high dose of ethanol during early postnatal life resulted in a deficit in spatial learning ability. This ability is controlled, at least in part, by the hippocampal formation. The purpose of the present study was to determine whether exposure of rats to ethanol during early postnatal life affected the number of specific neurons in the hippocampus. Wistar rats were exposed to a relatively high daily dose of ethanol between postnatal days 10 and 15 by placing them for 3 h each day in a chamber containing ethanol vapor. The blood ethanol concentration was about 430 mg/dl at the end of the exposure period. Groups of ethanol-treated (ET) rats, separation controls (SC), and mother-reared controls (MRC) were anesthetized and killed at 16 days of age by perfusion with phosphate-buffered glutaraldehyde (2.5%). The Cavalieri principle was used to determine the volume of various subdivisions of the hippocampal formation (CA1, CA2+CA3, hilus, and granule cell layer), and the physical disector method was used to estimate the numerical densities of neurons within each subdivision. The total number of neurons was calculated by multiplying estimates of the numerical density with the volume. There were, on average, about 441,000 granule cells in the granule cell layer and 153,000 to 177,000 pyramidal cells in both the CA1 and CA2+CA3 regions in all three treatment groups. In the hilus region, ET rats had about 27,000 neuronal cells. This was significantly fewer than the average of 38,000 such neurons estimated to be present in both MRC and SC animals. Thus, neurons in the hilus region may be particularly vulnerable to the effects of a high dose of ethanol exposure during early postnatal life.

Animals↗
PubMed2000

Helicases and aging.

Studying monogenic hereditary disorders that manifest age-related phenotypes in cells, tissues, and the total organism would be helpful for clarifying the mechanisms of aging. In this context, seven human disorders that manifest age-related phenotypes have been found to be caused by aberrations of five proteins with seven helicase motifs conserved in most of the helicases. These disorders are xeroderma pigmentosum, Cockayne syndrome, trichothiodystrophy, Bloom syndrome, Werner syndrome, X-linked alpha-thalassemia/mental retardation syndrome, and Juberg-Marsidi syndrome. A decline of probably pleiotropic and fundamental function of helicases in these disorders is, therefore, implied to underlie not only the various age-related phenotypes of the disorders but also the pleiotropic and universal nature of ordinary aging. Consistent with this implication, studies of these seven disorders suggest that their various age-related phenotypes are caused by aberrations in multiple processes, especially transcription. Furthermore, a few studies imply some association between aberration of the helicases and phenotypes in ordinary aging.

Aging↗
PubMed2000

Autogenous bone marrow graft to non-ossifying fibroma with a pathologic fracture.

Non-ossifying fibroma with a pathological fracture of the radius in a 10-year-old girl was successfully treated by curettage and autogenous bone marrow graft. The lesion was completely replaced by normal bone at 1 year after the operation. Autogenous bone-marrow graft was considered to be a useful method for the treatment of non-ossifying fibroma with minimal morbidity of the graft-harvesting site.

Bone Diseases, Developmental↗
PubMed2000

Association of ACE I/D polymorphism with cardiovascular risk factors.

Since the identification of an insertion/deletion (I/D) polymorphism in the angiotensin-converting enzyme (ACE) gene, the D allele has been recognized to be associated with cardiovascular disease. Moreover, significant associations of this polymorphism with multiple cardiovascular risk factors have been reported, although some studies failed to detect such associations. In the present study, we investigated the association of the ACE gene polymorphism with the parameters of multiple risk factors in 300 Japanese men who participated in a medical check-up. This investigation detected a significant association of the polymorphism with systolic blood pressure (P=0.007) and diastolic blood pressure (P=0.026), with their highest values in DD subjects and lowest values in II subjects. This significant association is consistent with the proposition that the polymorphism influences blood-pressure variability in men. Furthermore, we investigated the association of the polymorphism with four major disorders (obesity, hyperlipidemia, hypertension, diabetes mellitus) correlated with the risk for cardiovascular disease in the same 300 subjects. This investigation failed to detect any significant association of the polymorphism with each disorder. However, there was a trend that all four disorders were more frequent in ID and DD subjects than in II subjects. We therefore analyzed the association between the ACE gene polymorphism and having at least one of the four disorders in the same population. This analysis detected a significant difference: that ID and DD subjects had at least one of the four disorders more frequently than II subjects (P=0.008; odds ratio=1.89, 95% confidence interval= 1.19-2.99). Taken together, the results of this study are compatible with the proposition that the ACE polymorphism is associated with cardiovascular disease partially mediated through the four disorders in our population.

Adult↗
PubMed2000

Indocyanine green angiographic features of choroidal rupture and choroidal vascular injury after contusion ocular injury.

PURPOSE: To report features of choroidal rupture and choroidal vascular injury after contusion ocular injury on indocyanine green angiography. METHODS: In a prospective study, nine patients (nine eyes) with choroidal rupture after ocular contusion underwent initial fluorescein angiography and indocyanine green angiography within 19 days after trauma. Eyes that had a distinct abnormality of the retinal pigment epithelium were excluded from this study. Subtraction indocyanine green angiography was also performed. Follow-up fluorescein angiographic and indocyanine green angiographic findings were also studied. RESULTS: Initial ophthalmoscopic examination revealed subretinal hemorrhage in all nine eyes. In five of the nine eyes, choroidal rupture was not seen on initial ophthalmoscopic or fluorescein angiographic examination because it was hidden beneath the subretinal hemorrhage, but it was detected on subsequent examinations. In the remaining four eyes, choroidal rupture was observed by ophthalmoscopy at the time of initial examination, and these eyes exhibited hyperfluorescent streaks on fluorescein angiography in the region of the subretinal hemorrhage. On initial indocyanine green angiography of all nine eyes, observed hypofluorescent streaks became more obvious with time. For each eye, there were more hypofluorescent streaks on indocyanine green angiography than hyperfluorescent streaks on fluorescein angiography. In one eye, the location of indocyanine green leakage nearly coincided with the location of a hyperfluorescent streak on fluorescein angiography. In this case, crescentic streaks of hypofluorescence were seen on the temporal side of the subretinal hemorrhage on indocyanine green angiography, although choroidal rupture was not observed in that region by ophthalmoscopy or fluorescein angiography. In two of the nine eyes, indocyanine green angiography and the subtraction technique demonstrated disturbance of flow into choroidal vessels, especially at the choroidal rupture site. CONCLUSION: After ocular contusion injury, various features of choroidal rupture and choroidal vascular injury were observed on indocyanine green angiography. This technique may contribute to the diagnosis of choroidal rupture and to the understanding of the clinical course after injury.

Accidents, Traffic↗