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Biomedical subjects

K Yamanouchi

Publications and source records attributed to K Yamanouchi.

At least 37 records · Page 2Linked to original sources
PubMed2000

Acceleration of mounting behaviors in female rats by ibotenic acid lesions in the ventromedial hypothalamic nucleus.

To clarify the role of the ventromedial (VMH) or dorsomedial (DMH) hypothalamic nucleus in regulating male sexual behavior in female rats, radiofrequency or ibotenic acid lesions were made in ovariectomized rats, and three behavioral tests in total were carried out after implantation of Silastic tubes containing testosterone. As a result, females with radiofrequency or ibotenic acid lesions in the VMH showed higher levels of mounting behavior than those in females with no brain surgery or with sham-operation. The incidence of intromissive pattern in females with ibotenic acid lesions but not in females with radiofrequency lesions was higher than those in other female control groups. In the group of radiofrequency lesions in the DMH, both frequencies of mounting and intromissive pattern were lower than those in control and sham groups. No ejaculatory pattern was seen in any of the female groups. These results indicate that neuronal cell bodies in the VMH, but not in the DMH, exert an inhibitory influence on mounting activity in female rats.

Analysis of Variance↗
PubMed2000

Comparative analysis of HOXC-9 gene expression in murine hemochorial and caprine synepitheliochorial placentae by in situ hybridization.

Mammalian placentae exhibit wide structural diversity among different species and are formed under intricate interplay between the embryonic trophoblast and the maternal endometrial cells. Increasing evidence in the literature indicates a possible role played by homeobox genes in the complex placental organogenesis. Although the expression of all HOX 9 paralogs has been demonstrated both in highly invasive murine hemochorial placentae and in non-invasive caprine synepitheliochorial placentae, no reports so far published in the literature described the patterns of gene expression of Hoxc-9 in the murine nor those of HOXC-9 in the caprine placenta at cellular levels. We carried out comparative analyses of the location and identity of the cells expressing Hoxc-9/HOXC-9 during various stages of placentation in the murine hemochorial and caprine synepitheliochorial placentae by means of in situ hybridization using murine Hoxc-9 or caprine HOXC-9 cRNA probe, respectively. The results demonstrated that Hoxc-9 mRNA was expressed at high levels in giant trophoblast cells of murine placentae on Days 12-19, but not on Day 8. Similar analysis of caprine Day 75 and Day 100 placentae revealed that the binucleate trophoblast cells that penetrate the uterine luminal epithelial cell layer, strongly expressed HOXC-9 mRNA. Although the functional significance of Hoxc-9/HOXC-9 gene expression in trophoblast cells remains to be elucidated, it was suggested that it might play a role in the regulation of invasiveness or endocrine activities in the murine giant trophoblast cells and/or the caprine binucleate trophoblast cells.

Age Factors↗
PubMed2000

Identification of T-helper cell epitopes in the hypervariable region of the nucleocapsid (N) protein of rinderpest virus (RPV) in cattle.

The proliferative responses to synthetic peptides by lymphocytes derived from rinderpest virus (RPV)-infected cattle, the natural host for RPV, were assayed by determining [3H]thymidine incorporation into the DNA. In eight out of twelve cattle tested, significant responses were detected to peptides representing amino acids 452-501 in the C-terminal hypervariable region of the virus nucleocapsid (N) protein. It appears that helper T-cell epitope(s) for cattle which can be broadly recognized within an MHC diverse population, exists in this region of the protein.

Amino Acid Sequence↗
PubMed2000

Expression of myostatin gene in regenerating skeletal muscle of the rat and its localization.

The expression of myostatin mRNA was examined in regenerating skeletal muscle of the rat. Skeletal muscle regeneration was induced by injecting bupivacaine or hypertonic saline solution into the femoral muscle, and the tissues were collected 48 h after the treatment. In situ hybridization analysis revealed that the cells positive for myostatin message were localized in the regenerating area of the bupivacaine-treated tissues, where a numerous number of mononucleated cells were present. The myostatin-positive mononucleated cells contained both myogenic and nonmyogenic cells, as revealed by immunohistochemical staining for desmin and vimentin. Bupivacaine treatment to the testes resulted in no myostatin message expression in the testicular vimentin-positive cells, suggesting that the expression of myostatin message in vimentin-positive cells is a skeletal muscle-specific phenomenon. Furthermore, crushed muscle extract prepared from regenerating skeletal muscle had induced myostatin mRNA expression in skeletal muscle-derived fibroblasts in a dose-dependent manner. These results indicated that myostatin is expressed during skeletal muscle regeneration both in myogenic and nonmyogenic cells, and suggested that some factor(s) capable of inducing myostatin expression in fibroblasts are present in regenerating skeletal muscle.

Animals↗
PubMed2000

Establishment of fetal gonad/mesonephros coculture system using EGFP transgenic mice.

In developing mouse embryos, the Sertoli cells, Leydig cells, and seminiferous cords are differentiated in the XY gonads. The migration of mesonephric cells into the gonads is required during the developmental stage for seminiferous cord formation in the male gonads. In previous experiments, an organ coculture system has been used to examine morphologically developing gonads. However, by the process used in this system for fixing and staining the gonad/mesonephros complexes for examination, the kinetics of cell migration and the character of migrating cells cannot be observed. In the present study, we established an improved organ coculture system, using transgenic mice ubiquitously expressing Enhanced Green Fluorescent Protein (EGFP). In this system, time-dependent morphological changes in male-specific migration were observable in the gonad/mesonephros complex. The cell migration occurred at around 20 hr of coculture and began to spread at 25 hr with increases in the number of migrating cells occurring at 45 hr of coculture. No degenerative changes were detected at the end of coculture. Our results indicate that the present coculture system is very useful for investigating the mechanism of cell migration, as well as the characteristics of the migrating cells, in developing gonads. J. Exp. Zool. 286:320-327, 2000.

Animals↗
PubMed2000

Gallbladder volvulus: experience of six consecutive cases at an institute.

Recently we treated three patients with gallbladder volvulus within a short period. All three patients were examined preoperatively using computed tomography (CT). The first two cases were not diagnosed accurately before laparotomy. A precise diagnosis was made for the third one prior to surgery, based on our former experiences. Typical images, with marked edema and thickened wall of the gallbladder volvulus were shown on CT. We discuss six consecutive cases of the disease experienced at Hamamatsu Medical Center (i.e., the three patients rofed above, and three who did not have preoperative CT).

Aged↗
PubMed2000

Lordosis-inhibiting effect of progesterone in male and female rats with septal lesions.

The inhibitory role of progesterone (P) in regulating lordosis was investigated in male and female rats with septal lesions (SL). Male rats with SL showed lordosis quotients (LQ) as high as female rats with SL and female control rats without brain surgery after injection of 50 microg/kg estradiol benzoate (EB) followed by 0.5 mg P 44 h later. Even when primed with 5 mg P 1 h prior to the 50 microg EB-injection, the mean LQs were still high in all groups. When the dose of EB was decreased to 5 microg/kg, all rats showed high-score LQs. In contrast, all animals in both male and female in which 5 mg P was injected 1 h before 5 microg EB, showed low LQs. These results suggest that P is effective in suppressing lordosis enhanced by estrogen in either male rats or females. Furthermore, the high dose of estrogen overcomes the inhibitory action of P on lordosis in both sexes.

Animals↗
PubMed2000

An approach to the control of disease transmission in pig-to-human xenotransplantation.

Although several major immunologic hurdles need to be overcome, the pig is currently considered the most likely source animal of cells, tissues and organs for transplantation into humans. Concerns have been raised with regard to the potential for the transfer of infectious agents with the transplanted organ to the human recipient. This risk is perceived to be increased as it is likely that the patient will be iatrogenically immunocompromised and the organ-source pig may be genetically engineered in such a way to render its organs particularly susceptible to infection with human viruses. Furthermore, the risk may not be restricted to the recipient, but may have consequences for the health of others in the community. The identification of porcine endogenous retroviruses and of hitherto unknown viruses have given rise to the most concern. We document here the agents we believe should be excluded from the organ-source pigs. We discuss the likelihood of achieving this aim and outline the potential means by which it may best be achieved.

Animals↗
PubMed2000

Long-term protective immunity to rinderpest in cattle following a single vaccination with a recombinant vaccinia virus expressing the virus haemagglutinin protein.

A recombinant vaccine, produced by using a highly attenuated smallpox vaccine (LC16mO) as a vector and which expresses the rinderpest virus (RPV) haemagglutinin protein, has been developed. The properties of this vaccine, including its heat stability, efficacy in short-term trials, safety and genetic stability, have been confirmed in an earlier report. In the present study, the duration of the protective immunity generated by the vaccine in cattle was examined for up to 3 years following the administration of a single vaccination dose of 10(8) p.f.u. The vaccinated cattle were kept for 2 (group I) or 3 years (group II) and then challenged with a highly virulent strain of RPV. Four of five vaccinated cattle in group I and all six cattle in group II survived the challenge, some showing solid immunity without any clinical signs of rinderpest. Neutralizing antibodies were maintained at a significant level for up to 3 years and they increased rapidly following challenge. Lymphocyte proliferative responses to RPV were examined in group II cattle and were observed in four of the six vaccinated cattle in this group. The long-lasting protective immunity, in addition to the other properties confirmed previously, indicate the practical usefulness of this vaccine for field use.

Animals↗
PubMed2000

A new nasal acoustic reflection technique to estimate pharyngeal cross-sectional area during sleep.

The conventional acoustic reflection technique in which acoustic waves are launched through the mouth cannot be applied during sleep, nor can it be applied to the nasopharynx, which is the major site of occlusion in patients with obstructive sleep apnea syndrome. We propose a new technique of nasal acoustic reflection to measure pharyngeal cross-sectional areas including the nasopharynx. The acoustic waves are introduced simultaneously to both nostrils during spontaneous nasal breathing. A new algorithm takes into account the nasal septum with asymmetric nasal cavities on both sides and assumes prior knowledge of the cross-sectional area of the nasal cavities and the position of the nasal septum. This method was tested on an airway model with a septum and on healthy human subjects. The conventional technique gave inaccurate measurements for pharyngeal cross-sectional areas for an airway model with asymmetric branching, whereas the new technique measured them almost perfectly. The oro- and hypopharyngeal cross-sectional area measurements acquired by the new method were not different from those obtained by the conventional method in normal subjects. This new method can be used as a monitor of upper airway dimensions in nocturnal polysomnography.

Acoustics↗
PubMed2000

Decrease of sexual receptivity by prolylendopeptidase inhibitor in female rats.

The effects of a prolylendopeptidase inhibitor, 1-[3-(2-indanylanylacetyl)-L-thioprolyl]pyrrolidine (Z-321), on lordosis behavior were investigated in estrogen and progesterone-treated ovariectomized rats. Females were orally administered 100, 200 or 300 mg/kg Z-321 or the vehicle (control). The mean lordosis quotient in the rats given 300 mg/kg Z-321 was lower than that in control group, but that in rats given 100 or 200 mg/kg Z-321 was not lower. Thus, Z-321 suppressed lordosis in estrogen and progesterone-treated ovariectomized rats. Peptide neurotransmitters, especially those containing proline, are thought to be involved in the inhibitory mechanisms for lordosis behavior.

Animals↗
PubMed2000

Identification of skeletal muscle satellite cells by transfecting EGFP driven by skeletal alpha-actin promoter.

In isolating skeletal muscle satellite cells, sometimes a problem is encountered in removing contaminating nonmyogenic cells. In the present study, we constructed a novel vector, pSKA-EGFP, which achieves the expression of enhanced green fluorescent protein (EGFP) exclusively in myogenic cells under the control of skeletal alpha-actin promoter when transfected to primary cultured cells from skeletal muscle. Cells from rat skeletal muscle positive for EGFP after transfecting with pSKA-EGFP were all positive for desmin and none of the nonmyogenic cells expressed EGFP, indicating that the expression of EGFP is specific to myogenic cells. Among the cells positive for EGFP were proliferating cells, presumably satellite cells. In addition, EGFP positive cells derived from horse skeletal muscle after transfecting pSKA-EGFP in vitro formed multinuclear myotubes, indicating that myogenic expression of EGFP driven by skeletal alpha-actin was achieved also in the equine cells. These results indicated that pSKA-EGFP vector will be useful in identifying and following up the satellite cells in real time, and also permit us to isolate satellite cells in combination with fluorescence-activated cell sorting (FACS).

Actins↗
PubMed2000

In vitro studies on PGC or PGC-like cells in cultured yolk sac cells and embryonic stem cells of the mouse.

The present study aims: 1) to determine those conditions which promote the proliferation of primordial germ cells (PGCs) of the migratory phase in the yolk sac; and 2) to examine the effects of yolk sac cells as a feeder layer under the conditions mentioned above upon the embryonic stem (ES) cells (R1) with high potential for entering the germ line in vivo in chimeras. In murine yolk sac cells obtained on Day 10.5-11.5 of pregnancy and cultured in a modified Dulbecco's modified Eagle's medium (DMEM-plus/20: the postfix represents the concentration of FBS added in percentage), many cells exhibited strong immunoreactivities to the monoclonal antibodies 4C9 and 2C9 which are known to react with PGC specifically. Both the 4C9- and the 2C9-positive cells were sensitive to the treatment with busulfan added in vitro, supporting the supposition that they were PGCs. The respective numbers of the 4C9- and the 2C9-positive cells increased approximately 4 and 12 times when they were cultured in DMEM-plus/20 fortified with SCF, LIF, bFGF and TNF-alpha (DMEM-NT/20). When the R1 cells were cultured in the yolk sac-conditioned DMEM-NT/20 medium on the laminin substratum, the entire colonies were faintly stained with 4C9 but not with 2C9. At times solitary ES cells migrated out from the colonies, and reacted strongly with 4C9. When yolk sac cells and R1 cells were cultured on the two sides of a collagen-coated membrane, the yolk sac cells being feeder cells, some R1 cell colonies were intensely stained as a whole with either the 4C9 or the 2C9 antibody, suggesting that these colonies might be composed of cells clonally derived from stem cells which either had been destined to become the germ line cells or had already acquired cellular characteristics close to PGCs. It was tentatively concluded that the R1 cell population contained, as judged from the immunoreactivities, germ-cell-like cells, and that the yolk sac cells and/or their secretory products might facilitate the proliferation of, or the conversion of R1 cells to, the germ-cell-like cells.

Alkylating Agents↗
PubMed1999

Prevention of inhibitory effect of dorsal raphe nucleus lesions on ovulation and LH surge by 5-HT 2A/2C receptor agonists in female rats.

In order to investigate the role of the dorsal raphe nucleus and the serotonergic system in the regulation of ovulation, the number of ova and plasma luteinizing hormone (LH) concentrations were measured in female rats after making lesions in this nucleus (DRL) and/or treatment with 5-hydroxytryptamine (5-HT) receptor agonists or antagonists. DRL or sham lesion was made on the afternoon of proestrous (12:00-14:00 h) under ether anesthesia and the number of ova in the oviduct was counted on the next estrous and diestrous morning. In some animals, blood samples were taken via the atrial cannula during the proestrous evening for the radioimmunoassay of LH. All intact control and sham-operated females ovulated and plasma LH increased between 19:00 and 21:00 h. In contrast, ovulation was seen in only 36% of DRL rats. LH surge did not occur in this group. However, 80% of DRL rats ovulated after treatment with (+/-)-1-(4-iodo-2,5-dimethoxyphenyl)-2-aminopropane hydrochloride [(+/-)-DOI; a 5-HT 2A/2C receptor agonist] at 15:00 h on proestrous day. LH surge was also observed in the DRL rats with (+/-)-DOI. On the other hand, only 8% of DRL rats ovulated after treatment with buspirone (5-HT 1A receptor agonist). Furthermore, when mianserin (5-HT 2A/2C receptor antagonist) was administered at 16:00 h on proestrous day, ovulation was not seen in all rats without DRL. These results suggest that the dorsal raphe nucleus plays an important role in induction of LH surge and ovulation and the 5-HT 2A/2C receptor system is involved in this mechanism.

Animals↗
PubMed1999

Endometrial expression of cellular protooncogene c-ski and its regulation by estradiol-17beta.

The expression of the cellular protooncogene c-ski was examined in the rat uterus. In situ hybridization revealed that c-ski mRNA was expressed in the uterus of the adult rat on the day of estrous and localized mainly in the luminal and glandular epithelia. To test the possibility that the expression of c-ski mRNA is induced by estrogen, rats were ovariectomized and estradiol-17beta (E2) was injected. The expression of c-ski mRNA was upregulated 3 h after E2 treatment, reaching the highest level at 6 h and this persisted until 24 h; the E2-induced expression of c-ski mRNA was restricted to the luminal and glandular epithelia. These results suggest that the c-ski gene plays a role in uterine epithelial cell proliferation and mediates the proliferative action of E2.

Animals↗
PubMed1999

Efficient selection of transgenic mouse embryos using EGFP as a marker gene.

We have established a reliable method that uses the EGFP (Enhanced Green Fluorescent Protein) gene as a marker for selecting transgenic embryos from preimplantation embryos. Embryos that were subjected to the pronuclear microinjection of the CMV/beta-actin/EGFP fusion gene were cultured in vitro until they developed into the morulae- or blastocyst-stage. The expression of EGFP was easily observed by a fluorescent microscopy. There appeared to be no damage to the in vivo developmental ability of the embryos in response to the EGFP excitation light, which utilized an IB filter for a period of 30 min. Modified PCR analysis using Dpn I and Bal 31 digestion of the embryonic DNA showed that all of the embryos expressing EGFP in all their cells were transgenic, while more than half with mosaic expression of EGFP were not transgenic. Approximately 77% of pups born from the embryos that uniformly expressed the EGFP gene were transgenic, while 21.4% of pups from the embryos with mosaic expression were transgenics. The results showed that the use of EGFP as a marker is very useful and reliable for selecting transgenic embryos, and that it is important to transfer the embryos expressing EGFP in all their cells to obtain truly transgenic animals.

Actins↗