Biomedical subjects

Akira Hara

Publications and source records attributed to Akira Hara.

At least 19 recordsLinked to original sources

PubMed2006

Basaloid squamous cell carcinoma of the maxillary sinus: a report of two cases.

Basaloid squamous cell carcinoma (BSCC) is a highly aggressive neoplasm and a histologically distinctive variant of squamous cell carcinoma. Since the first description by Wain et al. in 1986, only 18 cases with BSCC in the nasal cavity or in the paranasal cavity have been reported in the English literature. We report herein two cases of BSCC of the maxillary sinus. Case 1 was 78-year-old man, who received preoperative radiotherapy and operation. He was alive without disease for 25 months after the operation. Case 2 was a 60-year-old man who received radiotherapy without operation. He died of lung metastasis 6 months after the initial diagnosis. We reviewed the clinical features of BSCC from the literature.

Aged↗

PubMed2006

The effects of the glucocorticoid receptor antagonist RU486 and phospholipase A2 inhibitor quinacrine on acoustic injury of the mouse cochlea.

Glucocorticoids are used clinically for the treatment of acoustic injury. However, the protective mechanism of glucocorticoid in acoustic injury has not been completely clarified. Also, the effects of phospholipase A2 (PLA2) on acoustic injury have not been examined to the best of our knowledge. The purpose of the present study was to examine the effects of methylprednisolone, a glucocorticoid receptor inhibitor (RU486) and a phospholipase A2 inhibitor (quinacrine) on cochlear injury induced by acoustic overexposure. Seventy-eight mice were exposed to a 4kHz pure tone at 128dB SPL for 4h. The auditory brainstem response (ABR) was used to examine the hearing thresholds. Cochlear morphology was examined to estimate the outer hair cell loss induced by acoustic overexposure. Methylprednisolone and quinacrine significantly alleviated the hearing threshold shift and hair cell loss induced by acoustic overexposure. RU486 antagonized the protective effect of methylprednisolone. The present findings suggest firstly that glucocorticoids exert protective effects against acoustic injury; secondly, that the protective effect of methylprednisolone was exerted by binding glucocorticoid receptors, and finally that activation of PLA2 may be involved in acoustic injury.

Acoustic Stimulation↗

PubMed2006

Stereoselective reduction of 4-benzoylpyridine in the heart of vertebrates.

The stereoselectivity in the reduction of 4-benzoylpyridine (4-BP) was examined in the cytosolic fractions from the heart of 9 vertebrates (pig, rabbit, guinea pig, rat, mouse, chicken, soft-shelled turtle, frog and flounder). 4-BP was stereoselectively reduced to S(-)-alpha-phenyl-4-pyridylmethanol [S(-)-PPOL] in the cytosolic fractions from the heart of pig, rabbit and guinea pig. However, of mammalian heart cytsol tested, only rat heart cytosol had little ability to reduce stereoselectively 4-BP. In an attempt to elucidate this reason, amino acid sequence of rat heart carbonyl reductase (RatHCR) was deduced from the cloned cDNA and compared with that of pig heart carbonyl reductase (PigHCR), which shows a high stereoselectivity in the reduction of 4-BP to S(-)-PPOL. RatHCR showed a high identity with PigHCR in amino acid sequence. Furthermore, recombinant RatHCR was confirmed to reduce stereoselectively 4-BP to S(-)-PPOL with a high optical purity comparable to recombinant PigHCR. It is possible that in the cytosolic fraction from the heart of rat, constitutive reductase other than RatHCR counteracts the stereoselective reduction of 4-BP to S(-)-PPOL, by catalyzing the reduction of 4-BP to the R(+)-enantiomer.

Alcohol Oxidoreductases↗

PubMed2006

Crystallization and preliminary X-ray crystallographic studies of pig heart carbonyl reductase.

Pig heart carbonyl reductase (PHCR), which belongs to the short-chain dehydrogenase/reductase (SDR) family, has been crystallized by the hanging-drop vapour-diffusion method. Two crystal forms (I and II) have been obtained in the presence of NADPH. Form I crystals belong to the tetragonal space group P4(2), with unit-cell parameters a = b = 109.61, c = 94.31 A, and diffract to 1.5 A resolution. Form II crystals belong to the tetragonal space group P4(1)2(1)2, with unit-cell parameters a = b = 120.10, c = 147.00 A, and diffract to 2.2 A resolution. Both crystal forms are suitable for X-ray structure analysis at high resolution.

Alcohol Oxidoreductases↗

PubMed2006

TNF-alpha decreases hsp 27 in human blood mononuclear cells: involvement of protein kinase c.

Treatment of PBMCs with TNF-alpha decreased the levels of heat shock protein (HSP) 27, but had little effect on the level of HSP70. Parallel to the decrease of HSP27, TNF-alpha increased the level of HSP27 in the incubation medium of the cells. The decrease of HSP27 induced by TNF-alpha was suppressed by the pretreatment of PBMCs with the specific protein kinase C (PKC) inhibitor, GF109203X. Furthermore, phorbol myristate acetate (PMA), a PKC stimulant, but not dibutyryl cyclic AMP, a protein kinase A stimulant, decreased the levels of HSP27. To investigate the effect of TNF-alpha on the oligomerization state of HSP27 in PBMCs, we performed sucrose density gradient centrifugation with subsequent fractionation and immunoassay. Extract of vehicle-treated PBMCs contained mainly dissociated forms of HSP27. The amounts of dissociated forms of HSP27 in PBMCs was decreased by TNF-alpha, while the amounts of aggregated form of HSP27 was little changed. In intact PBMCs, HSP27 is constitutively phosphorylated at Ser78, but not at Ser15 or at Ser82. The amount of phosphorylated HSP27 at Ser78 was decreased by TNF-alpha. These results indicate that TNF-alpha reduces HSP27 in PBMCs through PKC activation. This decrease may be due to efflux of dissociated form of HSP27, phosphorylated HSP27 at Ser78, from the cells.

Carcinogens↗

PubMed2006

Synchronous unilateral parotid gland neoplasms of three different histological types.

A 67-year-old male with three synchronous tumors in the unilateral parotid gland is reported. Postoperative histological examinations confirmed the presence of three synchronous primary tumors, specifically pleomorphic adenoma, Warthin's tumor and salivary duct carcinoma, in the right parotid gland. To our knowledge, this is the first case report describing three different histological types in the unilateral parotid gland.

Adenolymphoma↗

PubMed2006

Successful treatment of eosinophilic otitis media using ramatroban: report of two cases.

OBJECTIVE: The pathogenesis of eosinophilic otitis media is not yet fully understood. The purpose of this paper is to describe the clinical course of our two patients with eosinophilic otitis media and to discuss the pathogenesis and treatment of this intractable condition. METHODS: Two cases of eosinophilic otitis media were treated with ramatroban. RESULTS: The middle ear effusion has been well controlled in both patients for more than 1 year with minimal corticosteroid therapy. CONCLUSIONS: Our experience suggests that the pathogenesis of eosinophilic otitis media is related to the pharmaceutical effects of ramatroban, i.e., inhibition of the thromboxane A2 receptor (TP) and the chemoattractant receptor-homologous molecule expressed on Th2 cells (CRTH2).

Administration, Topical↗

PubMed2006

A new model of retinal photoreceptor cell degeneration induced by a chemical hypoxia-mimicking agent, cobalt chloride.

Retinal photoreceptor cell degeneration was induced by cobalt chloride, a chemical hypoxia-mimicking agent in rodents. Time course and dose-response of photoreceptor cell degeneration in mouse retina after intravitreal injection of cobalt chloride were examined by conventional histological analysis by hematoxylin and eosin staining and in situ terminal dUTP-biotin nick end labeling of DNA fragments (TUNEL) method with the use of paraffin-embedded sections. The dose-response of photoreceptor cell degeneration in rat retina was also examined. Photoreceptor cells progressively degenerated with time and under dose-response relationship. The suitable dose of cobalt chloride for the selective photoreceptor cell degeneration in mice is 10-12 nmol intravitreal injection at the volume of 2 microl. The retinal morphology of the mice 2 weeks after the 10-12 nmol intravitreal injection was similar to that of retinal degeneration in the mutant rd mouse. Retinal damage of total retinal layers was induced by an excessive dose of cobalt chloride. The progression of retinal damage after cobalt chloride injection, measured morphologically, was completed at 1 week. However, nuclear DNA fragmentation, mainly detected at outer nuclear layer by TUNEL, peaked at 48 h after 12 nmol cobalt chloride injection. Thus, the selective photoreceptor cell degeneration induced by cobalt chloride follows DNA fragmentation at outer nuclear layer. The photoreceptor cell degeneration is established optionally by cobalt chloride without use of the retinal degeneration mutant animals. Thus, we have described the development of a new model of retinal photoreceptor cell degeneration induced by a chemical hypoxia-mimicking agent.

Animals↗

PubMed2006

Aberrant promoter hypermethylation of p16 and MGMT genes in oral squamous cell carcinomas and the surrounding normal mucosa.

PURPOSE: Several genetic alterations have been reported to contribute to the development of oral squamous cell carcinoma (OSCC). Recent studies have shown roles of promoter hypermethylation of tumor suppressor genes, including p16 and MGMT, in several types of cancers. The purpose of this study is to examine the hypermethylation status of p16 and MGMT genes in both oral cancers and normal mucosa, surrounding the cancers. METHODS: Promoter hypermethylation status of p16 and MGMT genes were examined by the methylation-specific PCR (MSP) in OSCC (n = 51), verrucous carcinoma (n = 2), and carcinoma in situ (n = 2) tissues. Moreover, normal mucosa surrounding the cancers were also examined in 22 cases out of the 51 OSCCs. As a normal control, oral mucosa from healthy volunteers (n = 18) was used. RESULTS: Aberrant promoter hypermethylation of p16 and MGMT genes was detected in 50.9% (28 of 55) and 56.4% (31 of 55) of the total malignant cases, respectively. As for the 22 OSCC cases, in which paired cancerous tissues and the surrounding normal mucosa were examined simultaneously, promoter hypermethylation of p16 and MGMT genes was confirmed in 72.73% (16 of 22) and 68.18% (15 of 22), respectively. In contrast, as for the surrounding normal mucosa, promoter hypermethylation of p16 and MGMT genes was recognized in 27.27% (6 of 22) cases and 40.91% (9 of 22), respectively. CONCLUSIONS: Hypermethylation of both p16 and MGMT genes was frequently detected in not only OSCC tissues, but also the surrounding normal mucosa around the cancerous tissues. Thus promoter hypermethylation of p16 and MGMT genes are an important, probably early event in oral carcinogenesis.

Adult↗

PubMed2006

Intraocular injection of folate antagonist methotrexate induces neuronal differentiation of embryonic stem cells transplanted in the adult mouse retina.

Transplanted embryonic stem (ES) cells can be integrated into the retinas of adult mice as well-differentiated neuronal cells. However, the integrated ES cells also have a tumorigenic effect just because they have the ability for multipotential differentiation to various types of tissues. Thus, control of neoplastic potentials of ES cells is very important for the treatment of degenerative or injured diseases. Mouse ES cells carrying the sequence for the green fluorescent protein (GFP) gene were transplanted into adult mouse retinas by intravitreal injections 20 h after intravitreal N-methyl-d-aspartate (NMDA) administration. One week after the ES cell injection, folate antagonist methotrexate (MTX) was injected intravitreally. Eyes were retrieved 4 weeks after ES cell transplantation for histologic analyses. Conventional histological analysis was performed by hematoxylin and eosin staining with the use of paraffin-embedded sections. Neuronal differentiation and teratogenic potential of ES cells were demonstrated by immunohistochemistry. The proliferative activity of transplanted cells was detected by mitotic index, proliferating cell nuclear antigen index and AgNOR count. The incorporation of transplanted ES cells in MTX-treated and non-treated retinas at 4 weeks after transplantation was observed in 8/16 eyes (50%) and 8/16 eyes (50%), respectively. Transplanted ES cells in MTX-treated retina showed increased neuronal differentiation and decreased expression of teratogenic markers, compared with ES cells in non-treated retina. The proliferative activity of transplanted ES cells in MTX-treated retina was lower than that in non-treated retina. These results suggest that intravitreal MTX treatment following transplantation can induce neuronal differentiation in the transplanted ES cells and decrease their proliferative activity.

Alkaline Phosphatase↗

PubMed2006

Modifying effect of dietary sesaminol glucosides on the formation of azoxymethane-induced premalignant lesions of rat colon.

Sesame, which has been reported to have preventive effects against various disordered conditions, contains small quantities of lignans and several precursors to them such as sesaminol glucosides (SG). The lignans have the potent antioxidative activity and are suggested to have chemopreventive property. In the present study, we evaluated the modulating effect of SG on the development of colon precancerous lesions, aberrant crypt foci (ACF) and beta-catenin-accumulated crypts (BCAC), in the azoxymethane (AOM)-induced short-term model using male F344 rats. Dietary SG (500 ppm) significantly decreased the incidence of AOM-induced ACF when compared to the control (P<0.01). The incidences of AOM-induced BCAC in the SG-treated groups (250 or 500 ppm) were also significantly lower than that of the control group (P<0.01). Interestingly, administration of 500 ppm SG clearly decreased serum triglyceride level and mRNA expression of intestinal fatty acid-binding protein in the colonic mucosa, as compared to the control. These findings indicate that dietary SG inhibits AOM-induced carcinogenesis and suggest SG as a possible chemopreventive agent.

Animals↗

PubMed2006

The effects of tempol, 3-aminobenzamide and nitric oxide synthase inhibitors on acoustic injury of the mouse cochlea.

Oxygen free radicals have been implicated in the pathogenesis of acoustic injury of the cochlea. The purpose of this study was to evaluate the effects of tempol (a superoxide anion scavenger), 3-aminobenzamide (a poly (ADP-ribose) synthetase (PARS) inhibitor), N-nitro-l-arginine (a non-selective nitric oxide synthase (NOS) inhibitor), 7-nitroindazole (a selective neuronal NOS inhibitor) and aminoguanidine (a selective inducible NOS inhibitor) on acoustic injury. Mice were exposed to a 4 kHz pure tone of 110-128 dB SPL for 4h. Tempol, 3-aminobenzamide or N-nitro-l-arginine was intraperitoneally administered immediately before the onset of acoustic overexposure, while 7-nitroindazole or aminoguanidine was intraperitoneally administered every 12h starting immediately before the onset of acoustic overexposure. The threshold shift of the auditory brainstem response (ABR) and hair cell loss were then evaluated one and two weeks after acoustic overexposure. Tempol and 3-aminobenzamide significantly protected the cochlea against acoustic injury, whereas the NOS inhibitors did not exert any protective effect. These findings suggest that reactive oxygen species and PARS are involved in acoustic injury of the cochlea. However, further study is necessary to elucidate the roles of nitric oxide and nitric oxide synthase in acoustic injury.

Analysis of Variance↗

PubMed2006

Molecular cloning of a novel type of rat cytoplasmic 17beta-hydroxysteroid dehydrogenase distinct from the type 5 isozyme.

Rat liver contains two cytosolic enzymes (TBER1 and TBER2) that reduce 6-tert-butyl-2,3-epoxy-5-cyclohexene-1,4-dione into its 4R- and 4S-hydroxy metabolites. In this study, we cloned the cDNA for TBER1 and examined endogenous substrates using the homogenous recombinant enzyme. The cDNA encoded a protein composed of 323 amino acids belonging to the aldo-keto reductase family. The recombinant TBER1 efficiently oxidized 17beta-hydroxysteroids and xenobiotic alicyclic alcohols using NAD+ as the preferred coenzyme at pH 7.4, and showed low activity towards 20alpha- and 3alpha-hydroxysteroids, and 9-hydroxyprostaglandins. The enzyme was potently inhibited by diethylstilbestrol, hexestrol and zearalenone. The coenzyme specificity, broad substrate specificity and inhibitor sensitivity of the enzyme differed from those of rat NADPH-dependent 17beta-hydroxysteroid dehydrogenase type 5, which was cloned from the liver and characterized using the recombinant enzyme. The mRNA for TBER1 was highly expressed in rat liver, gastrointestinal tract and ovary, in contrast to specific expression of 17beta-hydroxysteroid dehydrogenase type 5 mRNA in the liver and kidney. Thus, TBER1 represents a novel type of 17beta-hydroxysteroid dehydrogenase with unique catalytic properties and tissue distribution. In addition, TBER2 was identified as 3alpha-hydroxysteroid dehydrogenase on chromatographic analysis of the enzyme activities in rat liver cytosol and characterization of the recombinant 3alpha-hydroxysteroid dehydrogenase.

17-Hydroxysteroid Dehydrogenases↗

PubMed2006

Therapeutic time window of methylprednisolone in acoustic injury.

HYPOTHESIS: This study aims to investigate the therapeutic time window of methylprednisolone in acoustic injury. BACKGROUND: Although glucocorticoids have been widely used in the treatment of acoustic injury, the therapeutic time window of glucocorticoids in acoustic injury has never been examined. METHODS: Mice were exposed to 4-kHz pure tone of 128-dB sound pressure level for 4 hours. Auditory brainstem response was examined before, immediately after, and 2 weeks after acoustic overexposure. RESULTS: Methylprednisolone significantly improved the auditory brainstem response threshold shifts 2 weeks after acoustic overexposure when it was administered before or immediately after acoustic overexposure, but not when administered 3 hours after acoustic overexposure. CONCLUSION: The present findings suggest that methylprednisolone possesses protective effects against acoustic injury of the cochlea with a short therapeutic time window.

Analysis of Variance↗

PubMed2006

Protective effects of glucocorticoids on ischemia-reperfusion injury of outer hair cells.

OBJECTIVE: This animal study aimed to investigate effects of glucocorticoids on the functional recovery of outer hair cells (OHCs) after transient ischemia. METHODS: Distortion-product otoacoustic emission (DPOAE) was examined before, during, and after transient cochlear ischemia of 30 minutes using albino guinea pigs. RESULTS: DPOAE decreased to noise level during ischemia. On recirculation, DPOAE initially recovered with time until 20 minutes after the onset of reperfusion, but thereafter, the DPOAE level gradually decreased toward the noise level in the control animals. Prednisolone and methylprednisolone significantly improved the DPOAE level 60 minutes after the onset of reperfusion. CONCLUSIONS: The present findings suggest that glucocorticoids possess protective effects against ischemia-reperfusion injury of OHCs.

Animals↗

PubMed2006

Temporal bone histopathologic abnormalities associated with mitochondrial mutation T7511C.

OBJECTIVES: We previously reported a mitochondrial T7511C mutation in the tRNA gene in a Japanese family with nonsyndromic hearing loss (HL). However, the temporal bone histopathology associated with T7511C has not been reported. The aim of the present study is to report histopathologic findings of a temporal bone from a patient in the Japanese family with this mutation. STUDY DESIGN: Single case study. METHODS: A temporal bone was obtained from the right ear of a male subject with progressive HL from 5 years of age and who died at 60 years of age from cerebral infarction. The bone was embedded, sectioned, and stained with hematoxylin-eosin for light microscopic study. Graphic reconstruction of the cochlea was performed using the method described by Schuknecht to determine loss of the stria vascularis and neurosensory elements including hair cells and spiral ganglion neurons. RESULTS: The most significant histopathologic finding was severe loss of spiral ganglion cells in all turns of the cochlea. Severe loss of neuronal filaments in Rosenthal's canal was also observed. The organ of Corti showed scattered loss of inner and outer hair cells in the basal turn. Partial atrophy of the stria vascularis was observed in all turns of the cochlea. CONCLUSION: Our results suggest that severe loss of spiral ganglion cells was the main cause of sensorineural HL associated with the T7511C mutation.

Atrophy↗

PubMed2006

Phylogenetic and structural analyses of the mating-type loci in Clavicipitaceae.

Entomopathogens and other econutritional fungi belonging to Clavicipitaceae were phylogenetically analyzed on the basis of the 18S rRNA gene and mating-type genes (MAT1-1-1 and MAT1-2-1). The phylogenies of the mating-type genes yielded better resolutions than that of 18S rRNA gene. Entomopathogens (Cordyceps bassiana, Cordyceps brongniartii, Cordyceps militaris, Cordyceps sinclairii, Cordyceps takaomontana, Isaria cateniannulata, Isaria farinosa, Isaria fumosorosea, Isaria javanica, Lecanicillium muscarium and Torrubiella flava) were considered as a phylogenetically defined group, and were closely related to mycopathogens (Lecanicillium psalliotae and Verticillium fungicola). They located at more descendant positions in the mating-type trees than other fungi, and lacked the mating-type gene MAT1-1-3. The deletion of MAT1-1-3 was supposed to have occurred once in Clavicipitaceae, and a good indication for the evolution of Clavicipitaceae. Other entomopathogens (Cordyceps cylindrica, Cordyceps subsessilis, Metarhizium anisopliae and Nomuraea rileyi) and pathogens of plants, nematodes and slime molds, were relatively related to each other, and possessed MAT1-1-3, but were supposed to be heterogeneous. Root-associated fungi did not form any clade with other species.

DNA, Fungal↗

PubMed2006

Substrate specificity of a mouse aldo-keto reductase (AKR1C12).

AKR1C12, a mouse member of the aldo-keto reductase (AKR) superfamily, is highly expressed in the stomach and is identical to a protein encoded in an interleukin-3-regulated gene in mouse myeloid cells, but its function remains unknown. In this study, the recombinant AKR1C12 was purified to homogeneity and the specificity for coenzymes and substrates was examined at a physiological pH of 7.4. The enzyme reduced various alpha-dicarbonyl compounds, several ketosteroids, aldehydes and some ketones using NADH as the preferred coenzyme. In the reverse reaction, the enzyme showed coenzyme preference for NAD+, and oxidized 3alpha-, 17beta- and 20alpha-hydroxysteroids, and non-steroidal aliphatic and alicyclic alcohols, of which many hydroxysteroids and geranylgeraniol were good substrates, exhibiting low Km and high kcat/Km values. The results, together with the intracellular high ratio of NAD+/NADH, suggest that AKR1C12 functions as a dehydrogenase for the endogenous hydroxysteroids and geranylgeraniol in mouse stomach and myeloid cells.

Alcohol Oxidoreductases↗