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Hiroshi Yoshikawa

Publications and source records attributed to Hiroshi Yoshikawa.

At least 19 recordsLinked to original sources
PubMed2006

The formation of g=2.49-species of cytochrome P450 in the rat liver by PCB126 oral administration: identification of heme axial ligands by EPR spectroscopy.

Rat livers and microsomes were subjected to electron paramagnetic resonance (EPR) measurements at 77 K. The EPR spectra of the livers from the control group, carbon tetrachloride-, 3-methylcholanthrene-, and 3,3',4,4',5-pentachlorobiphenyl (PCB126)-treated rats exhibited an EPR spectrum at g=2.40, 2.24, and 1.93, which is characteristic of P450 in a resting state. The liver of the PCB126-treated rats showed an additional distinct EPR spectrum at g=2.49, 2.26, and 1.87 (g=2.49-species). The heme environmental structure of g=2.49-species was identified by crystal field analysis using three EPR g-values of the microsome treated with various chemicals. These results indicated that g=2.49-species is a hemeprotein with cysteine thiolate at the 5th coordination site, and a nitrogenous ligand at the 6th site.

Administration, Oral↗
PubMed2006

Apoptosis in perforated cornea of a patient with graft-versus-host disease.

CASE REPORT: Although ocular complications associated with graft-versus-host disease (GVHD) can include corneal dysfunction, corneal perforation is not common. We report the presence of apoptotic cells in a perforated cornea of a patient with GVHD. A 72-year-old man with the angioimmunoblastic type of malignant lymphoma developed chronic GVHD after allogeneic peripheral blood stem cell transplantation. Despite systemic and topical treatment, both corneas perforated, and penetrating keratoplasty with cataract extraction and intraocular lens implantation was performed on both eyes. COMMENTS: The corneal button excised from the right eye was examined histologically and stained for apoptotic cells by TdT-mediated dUTP nick end labeling (TUNEL). This revealed thinning of the epithelial cell layer and stroma, with cells, including lymphocytes, infiltrating to the site of the perforation. Some of the epithelial cells and keratocytes were TUNEL positive. The presence of apoptotic cells in our case suggests that apoptosis may be involved in the perforation of the cornea in patients with GVHD.

Aged↗
PubMed2005

Identification of cytochrome P450 and glutathione-S-transferase genes preferentially expressed in chemosensory organs of the swallowtail butterfly, Papilio xuthus L.

The swallowtail butterfly, Papilio xuthus L., feeds exclusively on members of the plant family, Rutaceae. Female butterflies lay eggs in response to specific chemicals contained in their host plants. They perceive a variety of polar compounds as oviposition stimulants through the tarsal chemosensilla of the foreleg by drumming upon the leaf surface. We undertook an expressed sequence tag (EST) analysis to identify the chemosensory-related genes that are expressed in chemosensilla on the tarsus of P. xuthus. Several genes that showed similarity with biotransformation enzymes were identified from the ESTs. Among them, a cytochrome P450 and a glutathione-S-transferase (GST) were preferentially expressed in the chemosensory organs. We have determined the structure of both cDNA and genomic sequences encoding these enzymes and designated the P450 as CYP341A2, a novel member of CYP341A subfamily, and the GST as GST-pxcs1, respectively. We observed a localized expression of CYP341A2 at the base of tarsal chemosensilla by in situ hybridization. These results suggest that these degrading enzymes play a role in the chemosensory reception for host plant recognition.

Amino Acid Sequence↗
PubMed2004

A new method for the measurement of trace amounts of HONO in the atmosphere using an air-dragged aqua-membrane-type denuder and fluorescence detection.

A new method for the measurement of trace amounts of HONO has been developed. Nitrous acid in the ambient air is absorbed in an aqueous solution by an air-dragged aqua-membrane-type denuder. The absorbed nitrite is reacted with 2,3-diaminonaphthalene, and the formed 1-naphthotriazol is measured using a fluorescence method. The calibration curve of HONO shows a straight line from 0 to 4000 ppt, and the detection limit is estimated to be 8.1 ppt calculated as being three times of the base line noise. The time resolution, which is defined as the time required to become a constant value by changing from 0 to ca. 1000 ppt was 2 min. The present method is not affected by NO(2), NO, SO(2), O(3) NH(3) or mixtures of these gases and organic nitrate, organic carboxylic acids, alcohols and aldehydes. The determination results of HONO concentrations in the ambient air by the present method are in good agreement with those by the annular denuder system and the differential optical absorption method.

Air Pollutants↗
PubMed2004

Fibrinogen stimulates in vitro angiogenesis by choroidal endothelial cells via autocrine VEGF.

BACKGROUND: The purpose of this study is to investigate the effect of fibrinogen on angiogenesis in vitro formed by cultured bovine choroidal endothelial cells (BCECs) and the involvement of vascular endothelial growth factor (VEGF) in this mechanism. METHODS: For in vitro tube formation assay, BCECs were seeded on collagen gel containing fibrinogen (0-1.5 mg/ml). After 3 days of cultivation, the total length of the tubular structure was measured using Macscope Analyzer. Total RNA and conditioned media were collected after fibrinogen treatment and subjected to Northern and Western blot analyses, respectively. Transcription factor HIF-1alpha was also analyzed by Western blot analysis using cytosolic and nuclear fraction of BCECs. Involvement of VEGF in fibrinogen-dependent in vitro tube formation was evaluated using anti-VEGF neutralizing antibody or VEGF receptor 2-selective inhibitor (SU5416). RESULTS: Formation of the tubular structure was enhanced 20 to approximately 50 times in fibrinogen-containing gel in a concentration-dependent manner. The treatment of BCECs with fibrinogen resulted in a significant increase in VEGF gene and protein expression. Accumulation of HIF-1alpha protein in the nuclear fraction was also detected after the treatment with fibrinogen. Finally, fibrinogen-induced tube formation was significantly inhibited in the presence of anti-VEGF-neutralizing antibody (52.0% inhibition at the concentration of 1 microg/ml, P<0.05) or SU5416 (54.8% inhibition at the concentration of 3 microM, P<0.05). CONCLUSIONS: Extravasated fibrinogen might play an important role in the development of choroidal neovascularization associated with age-related macular degeneration, at least in part, through the function of VEGF in an autocrine manner. Transcription factor HIF-1 appears to be involved in fibrinogen-induced VEGF expression.

Angiogenesis Inhibitors↗
PubMed2004

Identification of amine receptors from a swallowtail butterfly, Papilio xuthus L.: cloning and mRNA localization in foreleg chemosensory organ for recognition of host plants.

The swallowtail butterfly, Papilio xuthus L., feeds exclusively on members of the plant family, Rutaceae. Female butterflies lay eggs in response to specific chemicals contained in their host plants. They perceive a variety of polar compounds as oviposition stimulants through the tarsal chemosensilla of the foreleg by drumming upon the leaf surface. Some biogenic amine analogs have been characterized as oviposition stimulants. We have cloned three amine receptors, serotonin, tyramine, and dopamine, from cDNA derived from foreleg tarsus of P. xuthus, and determined structures of both cDNA and genomic genes. The phenylethylamine (tyramine and dopamine) receptors were expressed preferentially in brain and chemosensory organs. Moreover, we observed the localized expression of dopamine receptors at the base of tarsal chemosensilla by in situ hybridization. These results suggest that amine receptors in tarsal chemosensilla have a functional role in chemoreception for host plant recognition.

Amino Acid Sequence↗
PubMed2004

Abnormal retinal vascular development in IL-18 knockout mice.

Recent studies have indicated that interleukin 18 (IL-18) might act as either an angiogenic or an angiostatic factor, but the true function of this protein in vascular development is unclear. We therefore investigated the role of IL-18 in the formation of retinal vessels. Development of the retinal vasculature was compared in IL-18 knockout (KO) and wild-type (WT) mice at several different time points. The formation of vessels was evaluated using angiography of flat-mounted retinal samples after inoculation with fluorescein dextran. Retinal samples from both groups were also evaluated through histological examinations, and the expression of angiogenic factors was examined using the reverse-transcription-polymerase chain reaction. The capillary retinal vessels in both WT and IL-18 KO mice had reached the peripheral retina by postnatal day (P) 7. However, IL-18 KO mice showed angiectasis and vascular leakage at P7, especially in the mid-peripheral retina. These symptoms were not observed in WT mice at any stage. Histopathological analysis confirmed abnormal vascular formation in IL-18 KO mice at P14. Interestingly, these abnormalities regressed over time and had disappeared by P84. Several angiogenesis-associated factors, including vascular endothelial growth factor (VEGF), basic fibroblast-growth factor (bFGF), platelet-derived growth factor (PDGF) and pigment epithelium-derived factor (PEDF), were overexpressed in the retinas of IL-18 KO mice compared with those of WT mice at P14. Interferon-gamma was detected only in WT mouse retinas at P14. These results provide new evidence for the role of IL-18 in retinal vascular development.

Angiogenic Proteins↗
PubMed2004

Anti-microbial action against verotoxigenic Escherichia coli O157:H7 of nitric oxide derived from sodium nitrite.

The levels of verotoxin-1 and verotoxin-2 released by verotoxigenic Escherichia coli O157:H7 treated in vitro with sodium nitrite, sodium chloride and several antibiotics were evaluated. Of the three strains of E. coli O157:H7 used in this study, two strains produced both verotoxin-1 and verotoxin-2, and one strain produced only verotoxin-2. Treatment of E. coli O157:H7 with sodium nitrite (6000 mg/l, minimum inhibitory concentration) did not increase the levels of verotoxin-1 and verotoxin-2 compared with a treatment by sodium chloride or antibiotics. When the electron paramagnetic resonance spectrum of sodium nitrite-treated bacterial cells was examined at 77 K to clarify the mechanism for the anti-bacterial activity of nitric oxide derived from sodium nitrite, electron paramagnetic resonance signals with g-values of 2.035 and 2.010 were observed. These were identified as being derived from iron-nitric oxide complexes. It appears that the dinitrosyl iron complexes in the E. coli O157:H7 cells were generated from the reaction of iron-sulfur proteins (enzymes) with nitric oxide formed by the reduction of sodium nitrite. The amount of ATP was decreased by the presence of sodium nitrite in the cell suspension. These findings indicate that nitric oxide derived from sodium nitrite penetrated the cells and inactivated enzymes related to the respiratory chain.

Adenosine Triphosphate↗
PubMed2003

Phacoanaphylaxis in Behçet's disease: a clinicopathologic and immunohistochemical study.

PURPOSE: To describe the occurrence of phacoanaphylaxis in enucleated eyes of patients with Behçet's disease. DESIGN: Retrospective, observational, case series and human tissue study. PARTICIPANTS: Twenty-six patients with Behçet's disease who underwent enucleation. METHODS: Histopathologic analysis was performed on 28 enucleated eyes of 26 patients with Behçet's disease. The eyes were divided into two groups, based on the absence or presence of tractional retinal detachment associated with cyclitic membrane formation. Selected eyes with tractional retinal detachment were stained for immunohistochemical examination. MAIN OUTCOME MEASURES: Histopathologic examination of enucleated eyes, including routine histopathologic and immunohistochemical studies. RESULTS: None of the five eyes without retinal detachment showed phacoanaphylaxis. Nine of the 23 eyes with detachment exhibited phacoanaphylaxis, 10 showed no inflammation of the lens, and four were aphakic. There was marked inflammatory cell infiltration in the cyclitic membrane of all nine eyes with phacoanaphylaxis. Immunohistochemical examination demonstrated positive staining for the macrophage markers in the epithelioid and giant cells. The average interval between onset of the ocular manifestations of Behçet's disease and enucleation was 63 months for eyes with phacoanaphylaxis and 35 months for eyes without phacoanaphylaxis (P<0.005). CONCLUSIONS: In Behçet's disease, eyes with long-standing intraocular inflammation complicated by cyclitic membrane formation may develop phacoanaphylaxis. Such patients may benefit from surgical removal of the cyclitic membrane along with the lens in eyes with significant visual function.

Adult↗
PubMed2003

A facial nerve study using transcranial magnetic paired stimulation.

OBJECTIVE: The purpose of this study was to evaluate the refractory period of the facial nerve by transcranial magnetic paired stimulation (TMPS) with as short interstimulus interval (ISI) as possible. Also, by applying TMPS, the long latency response obtained at the same time was recorded and its neurophysiological characteristics were studied. METHODS: (Experiment 1) The subjects comprised of 30 normal volunteers and 19 patients with Bell's palsy. The experiments were carried out using two sets of Magstim model 200 and Bistim modules, a large coil measuring 90 mm in diameter with a maximal output of 2.0 tesla (T), and a Neuropack 8 (Nihon Kohden Co., Japan) to control the stimulation and record the electromyographic findings. The amplitude of compound muscle action potentials (CMAP) to the orbicularis oris muscle was studied by TMPS at the parieto-occipital region. The ISI was set at 0.9, 1.1, 1.3, 1.5, 1.7, 1.9 and 2.1 ms in order to measure the refractory periods of the nerve. (Experiment 2) The subjects comprised of ten normal volunteers. The same method as in experiment 1 was carried out. However, this time, the lead electrodes were placed on the orbicularis oculi muscle, similar to that of the blink reflex. The ISI was set at 40, 60, 80, 100, 200, 300, 500, 800 and 1000 ms, and the effects of the facilitation and inhibition were studied. RESULTS: (Experiment 1) In normal subjects, when the ISI was less than 1 ms, a significant decrease in the amplitude was noted. In severe palsy cases with House-Brackmann Grade IV-V TMS yielded no response. In two of the cases of House-Brackmann Grade III, the CMAP was obtained. (Experiment 2) The long latency response with TMPS was most strongly inhibited when ISI was 80 ms. CONCLUSION: We were able to investigate the refractory periods, the reflex pathway of the facial nerve and the trigeminal nerve including the pons and the medulla oblongata by TMPS.

Action Potentials↗
PubMed2002

Scheduled conversion of replication complex architecture at replication origins of Saccharomyces cerevisiae during the cell cycle.

Replication of DNA within Saccharomyces cerevisiae chromosomes is initiated from multiple origins, whose activation follow their own inherent time schedules during the S phase of the cell cycle. It has been demonstrated that a characteristic replicative complex (RC) that includes an origin recognition complex is formed at each origin and shifts between post- and pre-replicative states during the cell cycle. We wanted to determine whether there was an association between this shift in the state of the RC and firing events at replication origins. Time course analyses of RC architecture using UV-footprinting with synchronously growing cells revealed that pre-replicative states at both early and late firing origins appeared simultaneously during late M phase, remained in this state during G(1) phase, and converted to the post-replicative state at various times during S phase. Because the conversion of the origin footprinting profiles and origin firing, as assessed by two-dimensional gel electrophoresis, occurred concomitantly at each origin, then these two events must be closely related. However, conversion of the late firing origin occurred without actual firing. This was observed when the late origin was suppressed in clb5-deficient cells and a replication fork originating from an outside origin replicated the late origin passively. This mechanism ensures that replication at each chromosomal locus occurs only once per cell cycle by shifting existing pre-RCs to the post-RC state, when it is replicated without firing.

Base Sequence↗
PubMed2002

Neovascularization in the anterior segment of the rabbit eye by experimental anterior ischemia.

PURPOSE: To investigate the effects of anterior ischemia accompanied by neither retinal nor choroidal ischemia on the anterior segment of the eye. METHODS: Both long posterior ciliary arteries in the right eye of 14 rabbits were directly cauterized with an electric coagulator. The eyes were enucleated 1, 2, 4, 7, 9 or 14 days after cauterization, then fixed with 4% paraformaldehyde. Semi-thin sections were studied by light microscopy. Several sections were stained with Griffonia simplicifolia lectin, which bound specifically to mammalian vascular endothelium. Other specimens were examined immunohistochemically for vascular endothelial growth factor (VEGF) protein. The tissue specimens of the first postoperative day were studied for expression of VEGF mRNA by in situ hybridization. RESULTS: Atrophy of the iris and ciliary body was seen after the second postoperative day. Corneal neovascularization appeared after 7 days. Neovascularization on the anterior surface of the iris and in the trabecular meshwork was detected after the ninth postoperative day. The proliferative tissues with newly formed vessels obstructed the iridocorneal angle 14 days after the treatment. There was no histological change in either the retina or choroid. Immunohistochemically, VEGF protein was detected in the epithelial and vascular cells of the iris on the first and fourth postoperative day. Expression of VEGF mRNA was detected in the epithelial cells of the ciliary body on the day following the treatment. CONCLUSIONS: Anterior segment ischemia, when unaccompanied by retinal ischemia, causes neovascularization in the cornea, iris and trabecular tissue.

Animals↗
PubMed2002

Cervical reflex induced by click stimuli in cats.

We studied click-evoked potentials in the anterior horn of the spinal cord in 17 cats. A concentric needle electrode was inserted into the anterior horn of the spinal cord at levels C3-C6. Potentials evoked with 105 dB SPL clicks were recorded with a peak latency of 4.89-5.10 ms only at the C3 level. These responses were observed 45-60 dB SPL above the auditory brainstem response (ABR) threshold, and no potentials were evoked by stimulation of the contralateral ear. Average was performed 100 times with changes in stimulation frequency of 1-20 Hz. The amplitude of the potentials decreased with increasing stimulus frequency, but there were no changes in ABRs. The responses disappeared after destruction of the medial vestibulospinal tract at the obex level, but ABRs were still recorded. The spinal nucleus of the accessory nerves was located in the anterior horn of the spinal cord at levels C1-C6, and the sternocleidomastoid muscle motoneurons were found at levels C1-C3. The click-evoked potentials recorded in this study reflect responses of the spinal nucleus of accessory nerves through the vestibulospinal tract to click stimulation. The responses have the same characteristics as vestibular-evoked myogenic potentials that can be recorded using surface electrodes over the sternoclei-domastoid muscles of humans.

Acoustic Stimulation↗
PubMed2002

Expression of nitric oxide synthase isoforms and detection of nitric oxide in rat placenta.

Nitric oxide (NO) production in the rat placenta was monitored and quantified by electron paramagnetic resonance (EPR) spectroscopy with hemoglobin and an Fe-N-(dithiocarboxy)sarcosine (DTCS) complex as NO-trapping reagents. Expression of nitric oxide synthase (NOS) isoforms was also examined by quantitative RT-PCR analysis. The EPR spectrum of the placenta with hemoglobin trapping showed a three-line hyperfine structure (g = 2.008 and a = 1.66-mT). The EPR signal was diminished after the placenta was homogenized or the NOS inhibitor L-NAME was administered to pregnant rats. Therefore, the specific signal was definitely identified as being derived from endogenous NO spin-trapped by hemoglobin, and the EPR spectrum showed that the NO adduct existed as a pentacoordinate alpha-NO heme species. The EPR spectrum of the placenta with Fe-DTCS trapping showed a triplet signal (g = 2.038) derived from an NO-Fe-DTCS complex. The height of the triplet signal did not vary significantly with gestational stage during the last few days of gestation. At the gestational stages examined, the level of NOS II mRNA expression was significantly higher than that of NOS III mRNA. NOS II expression in term (day 21.5) placenta was significantly increased compared with that in preterm (day 19.5) placenta (P < 0.01, n = 4 or 5). These results suggest that NOS II is the predominant producer of NO in the placenta and that NOS II-generated NO plays significant roles in the maintenance of placental functions immediately before birth.

Animals↗
PubMed2002

Changes in electrophysiological properties of rat skin with age.

The age-related changes in the electrical and physiological properties of the skin were examined in rats at the ages of 5, 10, 21, 90, and 180 d. The resistance of the stratum corneum, the resistance of the viable skin (epidermis and dermis), and the capacitance of the stratum corneum were analyzed from skin impedance data using an equivalent circuit. With development and aging, the resistance of the stratum corneum and the viable skin increased, whereas the capacitance of the stratum corneum decreased. Physiological characteristics such as the thickness of skin strata and the content of lipid and water in the stratum corneum were also measured. The lipid content in the stratum corneum was constant at all ages. The water content in the stratum corneum decreased, and the thickness of skin strata increased with age. Comparison between electrical data and physiological properties suggested that the increase in the resistance of the stratum corneum with aging is primarily caused by the decrease in the water content and that the capacitance of the stratum corneum and the resistance of the viable skin depend on age-related increases in the thickness of skin strata. In conclusion, the age dependency of cutaneous electrical properties may affect the permeation profile of drugs through the skin, and impedance analysis can be used to estimate age-related changes in transdermal drug delivery.

Animals↗