Search PubMed⌕ Search

Biomedical subjects

H Oshima

Publications and source records attributed to H Oshima.

432 records · Page 24Linked to original sources

Seasonal changes in steroidogenesis in the testis of the rhesus monkey (Macaca mulatta).

To investigate the influence of seasonal changes from breeding to nonbreeding season on testicular steroidogenesis in the adult rhesus monkey, two animals were hemiorchidectomized in November and the second testis of each was removed the following April. Intratesticular steroid concentrations related to the formation of testosterone from pregnenolone were measured by radioimmunoassay. Related steroidogenic enzyme activities were also assayed and dynamic studies of the bioconversion of radiolabeled precursor steroids by testicular microsomes were performed. Testosterone was synthesized from pregnenolone through both dehydroepiandrosterone and 17 alpha-hydroxyprogesterone. No distinct differences were found in the testosterone biosynthetic pathway between testes in breeding and nonbreeding seasons. In the breeding season, intratesticular testosterone concentrations, the sum of intratesticular steroids measured, and the ratio of testosterone to the steroid sum were increased when compared to those in the nonbreeding season. No major seasonal changes in microsome enzyme activities were found, although enzyme activities, except for delta 5-3 beta-hydroxysteroid dehydrogenase for C21-steroids, were slightly higher in the breeding season. We conclude that increased testosterone production in the testis during the breeding season is due primarily to increased pregnenolone supply from Leydig cell mitochondria and, to a lesser extent, to an enhanced pregnenolone bioconversion to testosterone in the microsomes.

3-Hydroxysteroid Dehydrogenases↗

Requirement of Notch 1 and its ligand jagged 2 expressions for spermatogenesis in rat and human testes.

It has already been demonstrated that the Notch signaling system is essential for gametogenesis in the adult germ line of Caenorhabditis elegans. However, the role of the Notch signaling system in mammalian spermatogenesis has not been well investigated. Recently, it has been revealed that this signaling system is expressed in the mammalian testis by showing coexpression of Jagged 2 and its receptor, Notch 1, is consistent with Notch 1 being a cognate receptor for Jagged 2 in the mammalian testis. Therefore, we investigated expressions of messenger RNAs of Notch 1 and Jagged 2 in the testicular tissues of developing Sprague-Dawley rats by reverse transcription-polymerase chain reaction and Northern blot analysis, expressions of their proteins in the testicular tissues of developing rats, fertile human controls and infertile human patients with maturation arrest by immunohistochemistry, and effects of antibodies to this system by culturing rat testicular tissues with these antibodies. Transcripts of Notch 1 and Jagged 2 in the rat testis were positive throughout the examined period; these intensities became higher at day 13 after birth, coincidence with the formation of spermatocytes, and peaked at day 19 after birth. Expressions of Notch 1 and Jagged 2 were recognized at first in the perinuclear regions of spermatocytes in the rat testis as a round structure at day 19 after birth and thereafter in further differentiated germ cells as meiosis proceeded. In the adult rat testis, positive staining was present as a round structure in spermatocytes, as a typical horseshoe-shaped structure in round spermatids, and as a covering structure spreading around the nucleus of elongated spermatids, but not in spermatozoa. Notch 1 was recognized in the vacuole of the Golgi complex of primary spermatocytes and the acrosome of elongated spermatids with electron microscopy. When rat testicular tissues were cultured with anti-Notch 1 or anti-Jagged 2 antibody, round and elongated spermatids decreased after 5 and 7 days of culture, respectively, and disappeared at around 9 and 12 days of culture, respectively, with shrinkage of the diameter of seminiferous tubules. Spermatocytes, however, increased after 11 days of culture. Expressions of both proteins have been detected in the testicular tissues of human fertile controls as in the rat testicular tissues. However, Notch 1 expression has not been detected in testicular tissues of 11 patients with maturation arrest, whereas Jagged 2 expression has been recognized in all of them. In conclusion, the results presented in this study offer the possibility that Notch 1/Jagged 2 signaling system plays an important role for male germ cells to differentiate or at least to survive in the rat testis and fails to express in the testis of spermatogenic maturation arrest patients.

Actins↗

Adenofibroma of the endometrium after tamoxifen therapy for breast cancer: MR findings.

We report a case of adenofibroma of the endometrium in a 69-year-old woman. This patient was receiving tamoxifen therapy after surgery for breast cancer. Magnetic resonance imaging showed an intracavitary mass containing multiple cystic components. We suggest adenofibroma as a possible diagnosis in cases of uterine masses with multiple cystic components and no clinical evidence of malignancy.

Adenofibroma↗

Embolization of collateral vessels using mechanically detachable coils in young children with congenital heart disease.

Our objective was to evaluate the usefulness of embolizing collateral vessels using mechanically detachable coils (MDCs) in children aged 3 years or younger with congenital heart disease. The subjects were 8 children with congenital heart disease featuring collateral vessels (age 18 days-3 years): 3 with a single ventricle, 2 with the tetralogy of Fallot, 2 with pulmonary atresia, and 1 with a ventricular septal defect. The embolized vessels were the major aortopulmonary collateral artery (MAPCA) in 5 patients, the persistent left superior vena cava in 2, and the coronary arteriovenous fistula in 1. A 4 or a 5 F catheter was used as the guiding device, and embolization was performed using MDCs and other conventional coils introduced through the microcatheter. One patient had growth of new MAPCAs after embolization, and these MAPCAs were also embolized with MDCs. Thus, a total of 9 embolization procedures were performed in 8 patients. Complete occlusion of the collateral vessels was achieved in 8 of 9 procedures (89%). Seven of 8 patients (88%) had uneventful courses after embolization, and MDC procedures appeared to play important roles in avoiding coil migration and achievement of safe coil embolization. One patient who underwent MAPCA embolization showed no improvement in heart function and died 2 months and 19 days later. Embolization of collateral vessels using MDCs in young children with congenital heart disease can be an effective procedure and a valuable adjunct to surgical management.

Child, Preschool↗

Transplantation of polymer-encapsulated fetal hippocampal cells into ischemic lesions of adult rat hippocampus.

In a previous study we demonstrated that fetal hippocampal cells, when transplanted into ischemic lesions of the adult rat hippocampus, can survive in large numbers in the host brain and show the innervation of the transplants by cholinergic fibers originated from the host brain. The present study was undertaken in an attempt to elucidate the hypothesis that the fiber connections forming synapses between the transplanted fetal neurons and the host brain play an important role in the survival of the transplanted cells. We transplanted the polymer-encapsulated fetal hippocampal cells prepared from E17-18 rat fetuses into the ischemic lesions in the adult rat hippocampus at which the CA1 pyramidal cells selectively died, and examined both histochemically or immunohistochemically for their survival and the expression of the synaptic vesicle protein, synaptophysin, and dendritic cytoskeltal protein, microtubule-associated protein 2 (MAP 2) within them. In addition, the cholinergic fibers originated from the host brain were examined by acetylcholine esterase (AChE) histochemistry. The results demonstrated that the polymer-encapsulated hippocampal cells could survive in the brain; however, the number of surviving cells markedly decreased following the transplantation, whereas no host-derived cholinergic fibers penetrated the polymer membrane of the capsules following the transplantation. In the cluster of surviving cells, only slight synaptophysin expression and no extensive growth of the dendrites were detected. The present results indicate that the direct contact between the host brain tissue and the transplant play an important role in the survival of such allografted neurons.

Acetylcholinesterase↗

Measurement of estrogenic activity of chemicals for the development of new dental polymers.

The estrogenic activities of 13 Bisphenol-A (BPA)-related chemicals for development of new polymers by three in vitro bioassay have been examined in the presence and absence of a post-mitochondrial metabolizing system (S9 mix). BPA, Bisphenol-B (BPB), Bisphenol-F (BPF), Bisphenol-S (BPS), 4,4-ethylidenebisphenol (BP1), 4,4-dihydroxybenzophenone (BP2), 2,2-bis (4-hydroxyphenyl)-hexafluoropropane (BP3), 4,4-(1,4-phenylenediisopropylidene) bisphenol (BP4), 4,4-cyclohexylidenebisphenol (BP5), 4,4-dihydroxydiphenyl ether (BP6), 4-hydroxydiphenylmethane (BP7), 4-cumylphenol (BP8) and 4,4-dihydroxydiphenyl sulfide (BP9) were each diluted with dimethyl sulfoxide to final concentrations ranging from 10(-7) to 10(-3) M in both the yeast two-hybrid system and in a fluorescence polarization system. Dilutions of 10(-9) to 10(-4) M were assayed in the E-screen, respectively. Except for BPS and BP4, the chemicals tested showed estrogenic activity in the absence of cut S9 mix preparation and the activity was enhanced with S9 mix. BPS, which was initially negative, was active with S9 mix in the yeast two-hybrid system. BP2 was weakly estrogenic with or without S9 mix. Chemicals other than BP2 were positive in the competition binding assay. All chemicals tested showed estrogenic activity in the E-screen, the concentration level of which was 10(4) times lower than those of the other two assays.

Animal Testing Alternatives↗

Genotoxicity of mercury used in chromosome aberration tests.

The purpose of this study was to investigate the genotoxic effects of Hg released from dental amalgams. The chromosome aberration test was conducted using original extracts and their diluted solutions of conventional type amalgam and high copper amalgam. The concentrations of Hg, Cu and Ag in the original extract of high copper amalgam were 17.64, 7.97 and 43.90 microM, respectively. Those in the original extract of conventional type amalgam were 20.63, 7.87 and 14.79 microM, respectively. 10 and 30 microM Hg(2+) were also used for comparison. The frequency of chromosome aberrations was below 5% with 0 microM Hg(2+) and with a triple dilution of high copper amalgam extract, containing 5.88 microM Hg, 14.63 microM Cu and 2.65 microM Ag. However, 9.5% of the cells showed chromosome aberrations with a quadruple dilution of conventional type amalgam, containing 5.15 microM Hg, 3.69 microM Cu and 1.96 microM Ag. The amount of Hg in the quadruple dilution of conventional type amalgam was less than that in the triple dilution of high copper amalgam extract and 10 microM Hg(2+). A concentration of 30 microM Hg(2+) caused 34.5% of the cells to show chromosome aberrations while with a two-thirds dilution of high copper amalgam extract, containing 11.76 microM Hg, 29.26 microM Cu and 5.31 microM Ag, 58.5% of the cells showed chromosome aberrations. A two-thirds dilution of high copper amalgam extract induced more chromosome aberrations than 30 microM Hg(2+), although the amount of Hg was less than 30 microM Hg(2+). A triple dilution of conventional type amalgam extract, original extracts of conventional type amalgam and high copper amalgam and 100 microM Hg(2+) were induced few metaphases. It was revealed that the conventional type amalgam induced chromosome aberrations with quadruple dilution where cell viability was about 80% and that the high copper amalgam induced a high level of chromosome aberrations with the two-thirds dilution. The effects of low level Hg on humans are not clear.

Animals↗

Distribution of gamma-glutamyl transpeptidase in male reproductive system of rats and its age-related changes.

The present study is designed to investigate localization of gamma-glutamyl transpeptidase (gamma-GTP) in male reproductive organs and its age-related changes using Wistar rats aged 2 to 15 weeks. Histochemically, gamma-GTP activity was detected intensively in epithelial cells of epididymides and seminal vesicles and weakly in those of anterior prostates, but not in testes under the present conditions. Biochemically, the highest gamma-GTP activity was found in epididymal head portions. The order of the activity was epididymides (head greater than body greater than tail), seminal vesicles, prostates and testes. The activity increases with sexual maturation in epididymides and seminal vesicles, but not in prostates. Since gamma-GTP is an enzyme involved in the incorporation of amino acids, the present findings suggest that not only epididymides but also seminal vesicles possess uptake mechanisms for amino acids.

Aging↗

Production of endothelin by canine prostatic epithelial cells and its stimulatory effects on their growth.

The current study has been designed to explore expressions of endothelin (ET) receptors and ETs in the canine prostate and the effect of ETs on canine prostatic epithelial cells. ET receptors were characterized by biotinylated ET-1 binding in frozen sections of the prostate. Canine prostatic epithelial cells in primary culture were used for demonstration of ET-1 expression by reverse-phase HPLC coupled with radioimmunoassay and Northern blotting and were subjected to growth assay. Biotinylated ET-1 binding was localized in the epithelial component, and the binding was also blocked with an antagonist specific for ET(B) subtype receptors. ET-1 and ET-3 stimulated canine prostatic epithelial cell growth in vitro. The effect was also reversed in the presence of an antagonist specific for ET(B) subtype receptors. Elution profile of epithelial cell culture medium revealed two peaks, corresponding to ET-1 and big ET-1. Epithelial cells in culture expressed pre-pro-ET-1 mRNA. Canine prostatic epithelial cells expressed ET(B) receptors and ET-1. It appears most likely that the expressed ET-1 acts as an autocrine/paracrine proliferative factor on canine prostatic epithelial cells via ET(B) receptors.

Animals↗

Determination of sodium azide in beverages by ion chromatography.

A convenient method for determination of sodium azide in beverages using ion chromatography is described. This method combines the specificity for azide with a simple sample preparation using a bubble and trap apparatus that removes any interferences. Sodium azide in a sample was acidified, and the azide was converted to the volatile hydrazoic acid, which was trapped in 2.5 mM sodium hydroxide solution. Determination was performed by isocratic ion chromatography using suppressed conductivity detection. Calibration curves were linear for 0.5 to 20 microg/mL sodium azide and the detection limit was 0.05 microg/mL. Recoveries of sodium azide from spiked samples (10.0 microg/g) were more than 82.6%. The method was then used to analyze various beverages.

Beverages↗

Inhibitory effect of N-acetylcysteine on invasion and MMP-9 production of T24 human bladder cancer cells.

BACKGROUND: MMPs play a crucial role in the process of cancer invasion and metastasis. METHODS: The influence of NAC on invasion and MMP-9 production of human bladder cancer cell line T24 was investigated using an in vitro invasion assay, gelatin zymography, Western and Northern blot analyses and RT-PCR assays. RESULTS: TPA increased the number of invading T24 cells through reconstituted basement membrane more than 10-fold compared to basal condition. NAC inhibited TPA-enhanced invasion dose-dependently. TPA increased the MMP-9 production by T24 cells without altering expression of TIMP-1 gene, while NAC suppressed TPA-enhanced production of MMP-9. Neither TPA nor NAC altered TIMP-1 mRNA level in T24 cells. In vitro experiments demonstrated that MMP-9 was directly inhibited by NAC but was not influenced by TPA. CONCLUSION: NAC limits invasion of T24 human bladder cancer cells by inhibiting the MMP-9 production in addition to a direct inhibition of MMP-9 activity.

Acetylcysteine↗

Screening method for determination of high levels of cadmium, lead, and copper in foods by polarized Zeeman atomic absorption spectrometry using discrete nebulization technique.

A screening method for determination of cadmium, lead, and copper in foods was developed. The sample (1-3 g) is digested with HNO3-H2SO4-HClO4 in a centrifuge tube attached to a straight glass tube that prevents loss of HNO3 by volatilization. After digestion, potassium iodide, H2SO4, and MIBK (4-methyl 2-pentanone) are added, and the metals are extracted with MIBK as metal iodides. The MIBK solution is injected and the metals are determined by flame polarized Zeeman atomic absorption spectrometry using a discrete nebulization technique. Recoveries of metals from fortified milk powder, unpolished rice, fish, beef, peanut butter, apple, and cabbage were satisfactory. The analytical results for NBS Oyster Tissue and NIES Pepperbush, Chlorella, and Mussel agreed with certified or reference values except lead in Pepperbush. The limits of quantitation for cadmium, lead, and copper were 0.01, 0.09, and 0.02 ppm, respectively. This method is simple and safe for routine analysis of high levels of cadmium, lead, and copper in foods.

Animals↗

Early embryonic cells activate the alternative complement system.

Murine embryonic stem cells, embryonic carcinoma cells and pre-implantation embryos were found to be extremely sensitive to cytolysis by normal human serum as compared to matured cells. The cytolytic activity to embryonic cells was not removed by pre-absorption of serum with spleen lymphocytes. Conditions which block both complement activation pathways or, selectively, the alternative pathway completely abrogated the activity of human serum against embryonic cells whereas the activity was retained under conditions which block the classical complement pathway, indicating that embryonic cells activate the alternative complement system (ACS). The cytotoxic effect to murine embryonic cells was reproduced using syngeneic murine serum. Concerning the mechanism of ACS-activation, the expression of regulators of complement activation and of membrane bound sialic acid was analysed. Embryonic cells express mRNA for Crry similarly to other cells but additionally express Cr2-transcripts not found in most adult cells. Embryonic cells have strikingly low levels of membrane-bound sialic acid compared to adult cells.

Animals↗

A new method to generate canine seminal emission and its application to men: direct electrical stimulation of the vas deferens.

Seminal emission from the ejaculatory duct (SEED) by direct electrical stimulation of the vas deferens was investigated in the dog, and the technique was applied to men. The stimulus parameters used were 2 msec, 10 Hz, and 8 V for dogs or 15-20 V for humans. In vitro studies using tetrodotoxin demonstrated that the major portion of the muscle contraction under the above stimulation was neurogenic. The stimulation of the pars epididymica, the middle vas, or the ampulla of the vas caused SEED in all dogs having intact hypogastric nerves (HNs) and receiving transection of bilateral HNs 1, 6, and 12 months before electrical stimulation. The dye instilled into the canine cauda epididymis was transported to the ampulla and emitted into the posterior urethra by electrical stimulation of the vas regardless of the site stimulated. The electrical stimulation of eight vasa deferentia (pars epididymica) of five prostatic carcinoma patients generated emission from the severed proximal end of all vasa examined at orchidectomy. All of the stimulations of 13 middle vasa of seven patients with emission loss caused SEED. The above results indicate that direct electrical stimulation of the canine and human vas deferens causes SEED regardless of the site stimulated or the absence of HNs, which are the major pathway of the efferent signal for SEED.

Animals↗

Analysis of methyl isothiocyanate in wine by gas chromatography with dual detection.

Methyl isothiocyanate (MITC) was extracted from a 5 mL wine sample with 2 mL dichloromethane, and the extract was washed with 5% sodium chloride solution. MITC was determined by gas chromatography with a dual nitrogen-phosphorus detector (NPD) and a flame photometric detector (FPD, S mode) (DB-210 column, 30 m x 0.53 mm id, column temperature, 70 degrees C). The limit of detection and quantitation of MITC with NPD-GC were 0.003 and 0.01 ppm, respectively. Average recoveries of MITC added to wine at 1 and 0.1 ppm were over 95%. This method is simple and rapid for routine analysis of MITC in wine.

Chromatography, Gas↗

Selective lysis of early embryonic cells by the alternative pathway of complement--a possible mechanism for programmed cell death in embryogenesis.

Early embryonic cells and early mouse embryos were shown to activate the alternative pathway of complement, and to be highly sensitive to complement-mediated cytolysis (Kircheis et al, In Vivo 9: 85-98, 1995). Under further development embryonic cells become resistant. The induction of resistance to the alternative pathway of complement correlates with: a) altered splicing of Cr2-transcript and b) changes in the acidic glycolipids under differentiation. Early embryonic cells have low amounts of sialic acid-containing glycolipids or express mainly GM3. The induction of differentiation changes the glycolipid pattern leading to an increase in membrane-bound sialic acid. The importance of membrane-bound sialic acid in the restriction of complement activation is demonstrated by increased sensitivity to complement after pre-treatment of cells with neuraminidase. The results indicate that there is target-specific lysis of early embryonic cells by the alternative pathway of complement. Early embryonic cells activate the alternative pathway of complement by expressing activators and low levels of membrane-bound sialic acid. Induction of differentiation changes the glycolipid pattern, leading to an increase in membrane-bound sialic acid sufficient to restrict complement-activation on the cell surface.

Animals↗