Biomedical subjects

Masaru Nakamura

Publications and source records attributed to Masaru Nakamura.

At least 19 recordsLinked to original sources

PubMed2006

Angiosarcoma with sacral origin metastasizing to the lung.

A 73-year-old man with fever, lumbago and hemosputum showed ground-glass opacity around multiple lung nodules on chest computed tomography. Examination of the man revealed anemia. Specimens obtained by video-assisted thoracic surgery revealed angiosarcoma, but the primary site of angiosarcoma could not be detected before autopsy. Angiosarcoma is a rare malignant neoplasm with rapid proliferation and they can arise at any region of the body. It can originate in the skin, soft tissue, liver or heart. Their multicentric and local recurrence easily leads us to misdiagnosis, and we have struggled to reach diagnosis and its origin. Angiosarcoma should be included in the different diagnosis of diffuse pulmonary hemorrhage with multiple lung nodules.

Aged↗

PubMed2006

Masculinization of female golden rabbitfish Siganus guttatus using an aromatase inhibitor treatment during sex differentiation.

To elucidate the involvement of endogenous estrogen (estradiol-17beta; E2) and the decisive factor (somatic or germinal element) in the ovarian differentiation of tropical marine teleosts, the effect of the aromatase inhibitor (AI) fadrozole on gonadal sex differentiation in the golden rabbitfish Siganus guttatus (Bloch) was examined for different dosages and periods of treatment. Fadrozole interrupted ovarian cavity formation at a dose of 500 microg g(-1) diet, while there was little effect at 10 or 100 microg g(-1). The gonads from both the 30-day and 90-day administration (500 microg g(-1) diet) groups were significantly biased toward testes (P=0.002 and <0.0001, respectively), which suggests strongly that E2 is involved in early ovarian differentiation and that its suppression is an indispensable condition for testicular differentiation in S. guttatus. The results from the two different AI treatment periods imply that the initial feminization of somatic gonadal elements determines subsequent ovarian differentiation, including oogenesis: a conclusion supported by the considerable time lag between ovarian cavity formation and subsequent oogenesis during normal ovarian differentiation in S. guttatus.

Animals↗

PubMed2006

Changes in androgen-producing cell size and circulating 11-ketotestosterone level during female-male sex change of honeycomb grouper Epinephelus merra.

11-ketotestosterone (11-KT), a potent male-specific androgen in fish, has important roles on spermatogenesis, male behavior, and nuptial coloration. The site of 11-KT synthesis and its role on male germ cell development during protogynous sex change is not clearly understood. We examined the dynamics of steroidogenic enzymes immunolocalization, viz cholesterol side-chain cleavage (P450scc), biomarker of steroids and cytochrome P45011beta-hydroxylase (P45011beta), downstream to 11-KT production, throughout the process of sex change in honeycomb grouper (Epinephelus merra). In female, P450scc immunoreactivity (-ir) was observed in the theca layer and tunica near blood vessels (BV). During the onset of sex change, P450scc reactive cells were observed in the remaining follicle layer of degenerated oocyte of the ovo-testis in early transitional (ET) and late transitional (LT). In male, P450scc-ir was localized in the interstitial Legdig cells of testis. P45011beta reactive cells were observed in the tunica near BV in female but not in theca layer. In ET and LT phases gonads, P45011beta localized in remaining follicle layer of degenerated oocyte and tunica near BV. On the other hand, in male, both interstices and tunica near BV showed strong signals against P45011beta. Moreover, in vivo and in vitro levels of 11-KT related with the changes in the nuclei diameter of P45011beta-positive cells in both tunica near BV and remaining follicle layer of degenerated oocyte to interstices during the progress of sex change. The present results suggest that 11-KT produced in the tunica near BV may provide the stimulus for female to degenerate oocytes and initiate sex change. However, 11-KT produced both in tunica near BV and remaining follicle layer of degenerated oocyte possibly plays critical role during testicular differentiation as well as gonadal restructuring at mid to late phases (ET to LT) of sex change in honeycomb grouper.

Androgens↗

PubMed2006

Endobronchial argon plasma coagulation for the management of post-intubation tracheal stenosis.

Post-intubation tracheal stenosis is usually caused by pressure necrosis at the cuff. Despite the fact that this phenomenon is well known and both large volume and low pressure cuffs have been developed, this lesion nevertheless continues to occur. Although the best results for tracheal reconstruction are obtained by an experienced surgeon, not all patients are able to undergo this operation for either medical or personal reasons. Argon plasma coagulation (APC) using flexible bronchoscopy has been successfully employed in the treatment of post-intubation tracheal stenosis in two of the surgery-refused and inoperable patients. The patients immediately experienced a relief of symptoms after APC. APC was thus performed 3-4 times every 1-2 weeks for each patient. In addition, there were no complications related to this procedure. The number of published clinical reports describing APC in benign airway stenosis are increasing. APC has also been reported to have several advantages over other interventional endobronchial techniques in the management of tracheo-bronchial stenosis. We report two patients, and to our knowledge this is the first description of APC being used in the treatment of endobronchial dilatation for post-intubation tracheal stenosis.

Aged↗

PubMed2006

Induction of female-to-male sex change in the honeycomb grouper (Epinephelus merra) by 11-ketotestosterone treatments.

The honeycomb grouper, Epinephelus merra, is a protogynous hermaphrodite fish. Sex steroid hormones play key roles in sex change of this species. A significant drop in endogenous estradiol-17beta (E2) levels alone triggers female-to-male sex change, and the subsequent elevation of 11-ketotestosterone (11KT) levels correlates with the progression of spermatogenesis. To elucidate the role of an androgen in sex change, we attempted to induce female-to-male sex change by exogenous 11KT treatments. The 75-day 11KT treatment caused 100% masculinization of pre-spawning females. Ovaries of the control (vehicle-treated) fish had oocytes at various stages of oogenesis, while the gonads of the 11KT-treated fish had transformed into testes; these contained spermatogenic germ cells at various stages, including an accumulation of spermatozoa in the sperm duct. In the sex-changed fish, plasma levels of E2 were significantly low, while both testosterone (T) and 11KT were significantly increased. Our results suggest that 11KT plays an important role in sex change in the honeycomb grouper. Whether the mechanism of 11KT-induced female-to-male sex change acts through direct stimulation of spermatogenesis in the ovary or via the inhibition of estrogen synthesis remains to be clarified.

Androgens↗

PubMed2006

Intratumor injection of small interfering RNA-targeting human papillomavirus 18 E6 and E7 successfully inhibits the growth of cervical cancer.

Human papillomavirus (HPV) 18 is related not only to squamous cell carcinoma of the cervix, but also to adenocarcinoma and small cell carcinoma of the cervix, in which prognosis is known to be poor. Small interfering RNA (siRNA) that targets HPV18 E6 and E7 was tested in HPV18-positive cell lines to investigate its effect and investigate its mechanism of action. Nude mice were also tested in a combination of siRNA and atelocollagen to determine whether it might be useful as a new molecule-targeting therapy for cervical cancer. siRNAs targeting HPV18 E6 and E7 were transfected into cervical cancer cells in vitro and they were investigated for cell growth inhibition, expression of E6 and E7 mRNA, expression of retinoblastoma protein, and senescence-associated beta-galactosidase staining. Sequence-specific siRNA inhibited cell growth. Decreased expression of E6 and E7 mRNA followed with E7 protein was observed in the transfected cells, but the expression of retinoblastoma protein and the beta-galactosidase staining increased, suggesting cell growth inhibitory effect through senescence. Treatment of xenografts established from SKG-II cells with siRNA specific for E6 and E7 obviously suppressed tumor growth in vivo. These results indicate that atelocollagen-mediated delivery of siRNA HPV18 E6 and E7 can be used as a novel therapeutic approach for cervical cancer.

Animals↗

PubMed2005

Suppression of steroidogenic enzyme expression during androgen-induced sex reversal in Nile tilapia (Oreochromis niloticus).

Exogenous sex steroids markedly alter sex differentiation in fish. The endocrine and molecular mechanisms involved in these changes remain unclear. To further clarify the mechanism of androgen-induced testicular differentiation, we treated female tilapia Oreochromis niloticus with methyltestosterone (MT at a dose of 50 microg/g diet) and examined the expression of P450 cholesterol-side-chain-cleavage, 3beta-hydroxysteroid dehydrogenase, and cytochrome P450 aromatase (P450arom) in the gonads. MT treatment resulted in 100% masculinization. Untreated fish showed normal ovarian differentiation with strong expression of all three steroidogenic enzymes. In gonads of MT-treated fish, expression of all three steroidogenic enzymes was attenuated within 15 days and completely disappeared within 30 days of treatment. Our results indicate that exogenous androgen treatment suppresses the expression of key steroidogenic enzymes, including P450arom throughout sex differentiation in tilapia, thus masculinizing the animal. Whether the absence of aromatase or the presence of androgens is responsible for testicular differentiation remains to be determined.

3-Hydroxysteroid Dehydrogenases↗

PubMed2005

Molecular cloning and expression of Ad4BP/SF-1 in the serial sex changing gobiid fish, Trimma okinawae.

Involvement of Ad4BP/SF-1 was investigated using the serial sex changing goby Trimma okinawae. First, a cDNA encoding Ad4BP/SF-1 was cloned from ovarian follicles. The open reading frame of goby Ad4BP/SF-1 encodes a protein of 489 amino acids. Ad4BP/SF-1 was expressed in gonadal tissues, brain, and kidney. Second, transcript levels of Ad4BP/SF-1 were measured in the ovary and testis of the same individuals. Expressions were related to sexual phases. Moreover, ovarian expression of Ad4BP/SF-1 increased during vitellogenesis and declined sharply during the post-vitellogenic period. Finally, the expression profile of Ad4BP/SF-1 was measured during serial sex change in the ovary. Ad4BP/SF-1 increased in parallel with the onset of the female-phase and decreased as female became male. Therefore, Ad4BP/SF-1 probably acts as an important indirect regulator of oocyte growth and maturation at female-phase of serial sex changing gobiid fish T. okinawae.

Amino Acid Sequence↗

PubMed2005

Evidence that estrogen regulates the sex change of honeycomb grouper (Epinephelus merra), a protogynous hermaphrodite fish.

Circulating estradiol-17beta (E2) levels decrease precipitously during female to male (protogynous) sex change in fish. Whether this drop in E2 levels is a cause or consequence of sex change is still largely unknown. The present study treated adult female honeycomb groupers (Epinephelus merra) with aromatase inhibitor (AI, Fadrozole), either alone or in combination with E2, to investigate the role of estrogen in protogynous sex change. Control fish had ovaries undergoing active vitellogenesis; the gonads of AI-treated fish had already developed into testes, which produced sperm capable of fertilization. In contrast, co-treatment of fish with E2 completely blocked AI-induced sex reversal. AI treatment significantly reduced circulating levels of E2, whereas the addition of E2 to AI prevented the loss. The plasma androgen (testosterone and 11-ketotestosterone) levels were increased in the AI-treated fish, while the levels in the E2-supplemented fish were low compared to controls. Present results show that E2 plays an important role in maintaining female sex of hermaphrodite fishes, and that the inhibition of E2 synthesis causes oocyte degeneration leading to testicular differentiation in the ovary.

Analysis of Variance↗

PubMed2005

Immunohistochemical evidence identifying the site of androgen production in the ovary of the protogynous grouper Epinephelus merra.

Androgen plays an important role in the developing ovaries of female fish. However, little is known regarding either the sites of production of androgen or its functional roles. In the present study, we investigated immunohistochemically the localization of cholesterol-side-chain-cleavage (P450scc) and cytochrome P45011beta-hydroxylase (P45011beta) with antibodies P450scc and P45011beta in the ovary of the female honeycomb grouper Epinephelus merra during its reproductive cycle. Clusters of strongly immunopositive cells, with 100-1000 cells in each cluster, against both P450scc and P45011beta, were observed throughout the annual reproductive cycle in tissue near blood vessels in the tunica ovary surrounding the outer periphery of the ovary. The ultrastructural characteristics of these cells showed that they were steroid-producing cells. In contrast, immunopositive cells against P450scc but not against P45011beta were localized in the theca layer surrounding the outer periphery of oocytes. These results suggest that two distinct steroid biosynthesis sites exist in the ovary and that cells at the two sites differ functionally. The only cells that biosynthesize 11-ketotestosterone are found in clusters in the vicinity of blood vessels; they possibly play a physiological role in oocyte growth and gonadal restructuring during the sex change of individuals of this species.

Androgens↗

PubMed2005

Aromatase immunoreactivity and the role of enzymes in steroid pathways for inducing sex change in the hermaphrodite gobiid fish Trimma okinawae.

The role of aromatase (Arom) in the process of bi-directional sex change in the gobiid fish Trimma okinawae was investigated by immunohistochemical methods. Irrespective of sexual phase, gonads comprised both ovarian and testicular tissues. In each sexual phase of females, the 2nd (2DF-M) and 4th (4DF-M) days after initiation of sex change to male, males, and the 2nd (2DM-F), 4th (4DM-F) and 6th (6DM-F) days after the initiation of reversion from male to female, ovarian and testicular histological observations were made. During the female, 2DF-M, 4DF-M and 6DM-F phases, the ovary contained vitellogenic and previtellogenic oocytes, compared with previtellogenic oocytes in the other phases. Although sperm was found in the testis in every phase, sperm ducts were apparent in the male phase, but not the female phase. Arom immunoreactivity was detected in the interstitial cells between the oocytes in all phases. On the other hand, it was localized in the thecal and granulosa cells of the follicular layer enclosing the oocytes in the female, 2DF-M, 4DF-M and 6DM-F phases. Activity of Arom in the thecal and granulosa cells is thought to be important for the development of oocytes and subsequent sex change.

Animals↗

PubMed2005

Gonadal structure of the serial-sex changing gobiid fish Trimma okinawae.

In order to obtain basic information about the role played by endogenous sex hormones in bringing about sex changes in the serial-sex changing gobiid fish Trimma okinawae, the gonadal structure of male and female phases were observed histologically. Steroid-producing cells (SPC; Leydig cells in a testis) were observed ultrastructurally in the ovaries and testes of both female-phase and male-phase fish. In addition, gonadal expression of P450 cholesterol side-chain-cleavage (scc) was examined immunohistochemically. Gonads of fish in female and male phases were observed to have both ovaries and testes simultaneously. Female-phase fish had matured with many developed vitellogenic oocytes, while male-phase individuals had immature ovaries with many numbers of previtellogenic oocytes at the perinucleolus stage. Testes of fish in different sexual phases had active spermatogenic germ cells. Organellae of SPC in the ovaries of female-phase fish had active structures of steroid production. In contrast, SPC in the ovaries of male-phase fish did not show active structures of steroid production. Immunopositive reactions against the scc antibody in the ovaries of female-phase fish were very strong, but immunoreactions in the ovaries of male-phase fish were very weak. In the testis, moderate immunopositive signals were obtained from dual-phase male/females.

Animals↗

PubMed2004

Comparison of two-color hologram lifetimes of near-stoichiometric lithium niobate and of tantalate crystals.

Lifetimes of two-color nonvolatile holograms recorded in undoped or in slightly doped near-stoichiometric lithium niobate and tantalate crystals were measured and compared by extrapolation of the high-temperature data. A proton-compensation mechanism dominated the dark decay and yielded similar activation energies, of 1.05 and 1.10 eV, for near-stoichiometric lithium niobate and tantalate crystals, respectively. The lifetime of holograms in lithium tantalate was 1 order of magnitude longer than that in lithium niobate with the same proton concentration, which was consistent with our theoretical estimation. The projected lifetime of two-color holograms in lithium tantalate without observable OH-absorption is longer than 50 years.

Journal Article↗

PubMed2004

Aromatase inhibitor induces complete sex change in the protogynous honeycomb grouper (Epinephelus merra).

The protogynous hermaphrodite fish change sex from female to male at the certain stages of life cycle. The endocrine mechanisms involved in gonadal restructuring throughout protogynous sex change are not clearly understood. In the present study, we implanted maturing female honeycomb groupers with nonsteroidal aromatase inhibitor (AI), Fadrozole (0, 1, and 10 mg/fish) and examined changes in gonadal structures and serum levels of sex steroid hormones 2(1/2) months after implantation. The ovaries of control females had oocytes undergoing active vitellogenesis, whereas AI caused females to develop into functional males. These males had testes, which were indistinguishable in structure from those of normal males, but bigger in size, and completed all stages of spermatogenesis including accumulation of large amount of sperm in the seminiferous tubules. AI significantly reduced the serum levels of estradiol-17beta (E2) and increased levels of testosterone (T), 11-ketotestosterone (11-KT), and 17alpha, 20beta-dihydroxy-4-pregnen-3-one (DHP). Further, AI suppressed in vitro production of E2, and stimulated the production of T and 11-KT in the ovarian fragments of mature female. In the honeycomb grouper, suppression of both in vitro and in vivo production of E2 and degeneration of oocytes by AI suggests that AI induces complete sex change through inhibition of estrogen biosynthesis, and perhaps, subsequent induction of androgen function.

Animals↗

PubMed2004

Exogenous expression of interferon-beta in cultured brain microvessel endothelial cells.

Brain microvessel endothelial cells (BMECs) make up the blood-brain barrier (BBB) and regulate the passage of therapeutic proteins as well as drugs from the cerebrovasucular circulation to the brain. In the present study, we transferred mouse or human interferon-beta (IFN-beta) gene via cationic liposomes into primary cultures of bovine BMECs developed as an in vitro model of the BBB. The gene-transferred BMECs secreted transiently a substantial amount of IFN activity more efficiently during the growth phase than at confluence. This was suggested to be due to a difference in the potential for plasmid incorporation between growing and confluent BMECs in a series of cell association experiments with (32)P-labelled plasmid DNA. Furthermore, when BMEC monolayers in Transwell plates were transfected with the IFN-beta-expression vectors from the upper side, IFN-beta was predominantly detected in the upper compartments, suggesting polarized secretion of the transgene products in BMEC monolayers. These findings provide important basic information about therapeutic secretory protein gene delivery to BMECs.

Animals↗

PubMed2004

Expression and visualization of a human interferon-beta-enhanced green fluorescent protein chimeric molecule in cultured cells.

We have constructed a recombinant cDNA encoding the chimeric protein between human IFN-beta (HuIFN-beta) and enhanced green fluorescent protein (EGFP) to elucidate the intracellular localization of IFN-beta. Transient expression of the chimeric molecule, HuIFN-beta-EGFP, in L cells demonstrated that the chimeric molecule secreted from the cells had an intact biological activity as far as antiviral effect was concerned. Immunostaining of the transfected cells using anti-HuIFN-beta antibody demonstrated that green-fluorescence was co-localized with the IFN signal and its profile was similar to IFN signals in the cells transfected with HuIFN-beta expressing plasmid DNA. These results indicate that the HuIFN-beta-EGFP chimeric gene was expressed as a chimeric protein and the chimera was transported via the regular secretory pathway in the cells. In other cell types, the fluorescence derived from the chimeric protein was also seen on cytoplasmic vesicular structures. These results suggest that HuIFN-beta-EGFP will be a useful tool to investigate the intracellular trafficking processes of HuIFN-beta in a variety of cell types.

Animals↗

PubMed2004

Identification of estrogenic compounds in wastewater effluent.

In order to identify the dominant contributors to estrogenic activity in environmental waters, a comprehensive fractionation method using silica gel column chromatography, combined with recombinant yeast assay for detecting estrogenic activity and with gas chromatography-mass spectrometry for quantifying endocrine disruptors and natural estrogens, was developed. The method was applied to the municipal sewage treatment plant (STP) secondary effluent discharged to the Tamagawa River in Tokyo, Japan, where endocrine disruption was observed in wild carp. The instrumental analysis demonstrated that averaged concentrations of nonylphenol, bisphenol A, estrone (E1), and 17beta-estradiol (E2) were 564 +/- 127, 27 +/- 19, 33 +/- 11, and 4.6 +/- 3.0 ng/L, respectively. Based on the concentration and relative potency of these compounds, the natural estrogens E1 and E2 represented more than 98% of the total estrogen equivalent concentration (EEQ) in the STP effluent, while the contribution of phenolic compounds to total EEQ was less than 2%. Estrogenic activities associated with the dissolved phase of the effluent samples were detected by a recombinant yeast assay. By using silica gel column chromatography, the dissolved phase was separated into several fractions that were subjected to the bioassay. The polar fractions exhibited estrogenic activity. The greatest estrogenic activity was found in a polar fraction containing E1 and E2 and represented 66 to 88% of the total estrogenic activities estimated from the bioassay data. These results lead to the conclusion that E1 and E2 were the dominant environmental estrogens in the STP effluent, but a significant contribution to estrogenic activities stems from unidentified components in the effluents.

Biological Assay↗

PubMed2004

Sex inversion of sexually immature honeycomb grouper (Epinephelus merra) by aromatase inhibitor.

Previous studies have shown that estrogen plays an important role in sex change of protogynous honeycomb grouper, and that the treatments with aromatase inhibitor (AI) cause estrogen depletion and complete sex inversion of pre-spawning females into functional males. In the present study, we examined whether AI causes sex inversion of sexually immature females. Female honeycomb groupers were implanted with various doses of Fadrozole (0, 100, 500 and 1000 microg/fish) in the non-breeding season, and resultant changes in the gonadal structures and the plasma levels of sex steroid hormones (estradiol-17 beta, E2; testosterone, T; 11-ketotestosterone, 11-KT) were examined three months after implantation. Vehicle-implanted groups did not change sex, while 100 and 500 microg AI-implanted groups had turned into transitionals with intersex gonad. In contrast, the highest dose receiving group exhibited both transitional and male phases. Transitional phase gonad had atretic oocytes and spermatogenic germ cells at the late stages of spermatogenesis, while male phase testis contained spermatozoa accumulated in the seminiferous tubules. All males released sperm upon slight pressure on the abdomen. In the AI-implanted fish, plasma levels of E2 decreased in a dose-dependent manner, while the levels of 11-KT were high in the highest dose receiving group. Present results suggest that estrogen plays an important role in sex change of protogynous honeycomb grouper, and that treatments with AI potentially inhibits endogenous E2 production in vivo, causing oocyte degeneration and subsequently the sex inversion from female to male. The Fadrozole could be an important tool for manipulating the sex of hermaphrodite fishes.

Animals↗