Biomedical subjects

Y Kon

Publications and source records attributed to Y Kon.

At least 55 records · Page 3Linked to original sources

PubMed1998

Visualization of the topographical structure of the anesthetized mouse brain by MR microimaging.

A nuclear magnetic resonance (NMR) spectrometer equipped with a magnet producing a high and extremely uniform magnetic field (7.05 T) was combined with a strong field gradient coil (3.5 mT/cm) and applied to MR microimaging of the mouse brain to visualize its topographical structure. Since the proton-density-weighted condition (long repetition time (TR) and short echo time (TE); TR/TE = 3,000 ms/10.4 ms) was found to be the most suitable for imaging the mouse brain, mid-sagittal and coronal sections in 1-mm- or 0.3-mm-thick slices were imaged according to the multislice spin echo sequence with 2 or 8 acquisitions, a 2 kHz pulse width and a 256 x 256 data matrix. As expected, the resolution of MR microimaging was comparable to that of the histological sections. The white matter especially, could be distinguished from the gray matter in some regions of the brain. Coronal sections of the brain also showed that the hippocampal CA1-CA3 regions were distinguishable from the other regions. The results suggested that the present MR microimaging technique might be a useful tool for the study of topological anatomy and submicroscopic research using brains of small laboratory animals.

Animals↗

PubMed1998

Retroviral sequence located in border region of short unique region and short terminal repeat of Md5 strain of Marek's disease virus type 1.

A 246-base pair (bp) retroviral sequence, which was homologous to a long terminal repeat of avian erythroblastosis virus (AEV), was detected and cloned from Md5 strain (Md5) of Marek's disease virus type 1 (MDV1) by representational difference analysis (RDA). The retroviral sequence was thought to be located in the border region of short unique region (U(s) and short terminal repeat (TRs), but did not exist in the border region of U(s) and the inverted short repeat (IRs) of the Md5 genome. A cloned fragment of the US/TRs border region of the Md5 genome showed a construction of U-E'-R-U'-E-TRs with the regions designated as follows: E, expanded TRs reported by Jones et al. [Proc. Natl. Acad. Sci. U.S.A. 90, 3855, 1993]; E', a partial copy of the expanded TRs; R, the retroviral sequence detected in Md5 genome; U, TRs-end sequence of U(s); U', a partial copy of TRs-end sequence of U(s). The sequence unit indicated as E'-R-U' was thought to be heterogeneously repeated in the Md5 genome. Since this retroviral sequence reportedly did not exist in the original stock of Md5, the retroviral sequence is thought to be inserted in the Md5 genome without experimental co-infection of avian cells with retrovirus and MDV1. These results suggest that RDA could be useful for the detection of retroviral sequences in the herpesvirus genome.

Alpharetrovirus↗

PubMed1998

Transcriptional analysis of Marek's disease virus (MDV) genes in MDV-transformed lymphoblastoid cell lines without MDV-activated cells.

Spontaneously activated MDV is rarely included in MDV-transformed cells, while it may influence the results of transcriptional analysis. A population consisting of 10(3) MDV-transformed cells probably did not include spontaneously activated MDV, since the estimated frequency of MDV-transformed cells including activated MDV was below 0.01% according to limiting-dilution polymerase chain reaction (PCR) and the presence of the major early antigen pp38 in 6 transformed cell lines. Reverse transcriptase-PCR (RT-PCR) products corresponding to ICP27, pol, TK, US3, A41, gA, gB and UL50 genes were undetectable in 10(3) cells by Southern hybridization of the RT-PCR products. Transcripts of the VP16 and SORF2 genes were detected in the 10(3) cells of MSB-1, and the pp14 gene transcript was found in 10(3) cells of RPL-1 but not in 10(3) cells of HPRS-1, MOGA-2, MSB-1 or MTB-1. A transcript corresponding to the ICP4 sequence was detected as a 0.7 kbp RT-PCR product in 10(3) cells of these MDV cell lines but not in the retrovirus-transformed 1104B1 cell line. The transcript corresponding to the 0.7 kbp RT-PCR product suggested a splice by its size and sequence. Thus, transcriptional analysis of 10(3) MDV-transformed cells revealed that the transcript corresponding to the ICP4 sequence was a common transcript in latently infected MDV-transformed cells, while most of the genes did not transcribe in these cells.

Animals↗

PubMed1997

Chromosomal mapping and developmental study of Tattered-Hokkaido (Tdho).

We found a new X-linked dominant mouse mutation. This mouse has the same phenotype as Td, which exhibits hyperkeratotic skin, reduced viability in affected females, a tendency to be smaller, lighter weight than the normal sibs during weaning age, and prenatal lethality in affected males. To map the locus, we tested 267 progeny from an intraspecific backcross between affected females and wild-origin strain males. Polymerase chain reaction (PCR) was performed with microsatellite markers of the proximal region of the mouse X Chromosome (Chr). This mutant showed no recombination with DXMit 123, DXMit 55, or DXMit 26. The gene position and phenotype of this mutant were very similar to those of Td. Therefore, it is speculated that the new mutant gene is a multiple allele of Td, and we designated it Tattered-Hokkaido (Tdho). Linkage analysis of these animals suggested a possible gene order of cen-(Tdho, DXMit123, DXMit55, DXMit26)-DXMit161-DXMit54-DXMit103-DXMit52 -DXMit190-DXMit138) in the X Chr. Prenatal lethality of male mutants was also investigated, with 12.5 to 16.5 embryonic day (E) backcrossed embryos from affected F1 females. It was found that the male mutants died between E12.5 and E14.5. The cause of death of male mutants is discussed in relation with the other proximal genes of the X Chr.

Animals↗

PubMed1997

Progressive effect of alpha-phenyl-N-tert-butyl nitrone (PBN) on rat embryo development in vitro.

In the present study we demonstrated the effects of the spin-trapping agent alpha-phenyl-N-tert-butylnitrone (PBN) on the in vitro development of rat embryos at the early stage. In rat embryos, PBN increased the speed of the first cleavage and had no toxicity during pregnancy after embryo culture. These results showed that reactive oxygen species (ROIs) that were formed by activating molecular oxygens through redox reactions regulated the speed of development for early-stage embryos. Thus, PBN caused a decrease in the level of ROIs and toxicity and an in increase in the level of the development of rat embryos. On the other hand, PBN could not decrease the 2-cell block in vitro nor increase the blastulation rate, in contrast to the fact that a scavenger of superoxide anions, SOD, is effective in doing so for mouse embryos. From these results it was concluded that free radicals play an important role in the in vitro development of rat embryos at the early stage, but play no role in the decrease of the 2-cell block or their blastulation rate. It should be noted that PBN had no toxicity for embryonic development at the 2-cell stage.

Animals↗

PubMed1997

Resistance to infection with mouse hepatitis virus (MHV) in the cell clones derived from persistently infected DBT cells with the JHM strain of MHV.

PiD-10 and piD-11 cells that have been established from persistently infected DBT cells with the JHM strain of MHV (JHMV) were resistant to infection with JHMV. There was no significant difference in the amount of adsorbed virus among piD-10, piD-11 and DBT cells. When an expression of mRNA of the MHV receptor in piD-10 and piD-11 cells was analyzed by the RT-PCR method, no significant difference was observed in the intensities of the amplified products among piD-10, piD-11 and DBT cells. Treatment of virus-adsorbed cells with PEG, which induces fusion of the cellular membrane with the viral envelop, causes entry of virus particles into cells. There was no significant difference in the yields of virus between PEG-treated and PEG-untreated cells. The titers of infectious virus internalized into piD-10 and piD-11 cells were the same as those in DBT cells. When piD-10 and piD-11 cells were fused with PEG and infected with JHMV, the yields of infectious virion particles from the fused cells between piD-10 and piD-11 cells were significantly lower than those from the fused cells between DBT and piD-10 or piD-11 cells. The present study showed that resistance of piD-10 and piD-11 cells to JHMV infection is not due to an inhibition of JHMV entry into the cells.

Animals↗

PubMed1997

Apoptosis in peripheral CD4+T cells and thymocytes by Marek's disease virus-infection.

Histological study revealed that Marek's disease virus (MDV) can cause apoptosis in peripheral blood lymphocytes (PBL) in latently infected chickens. Analysis of DNA fragmentation indicated that CD4+T cells but not CD8+T cells underwent apoptosis. These apoptotic changes were also observed in the thymus during the acute phase of the infection. Flow cytometry analysis showed the drastic decrease of CD4+CD8+ thymocytes, indicating that MDV can induce apoptosis in CD4+CD8+ immature thymocytes in acutely infected chickens. These changes might be involved in the immuno-suppression induced by MDV.

Animals↗

PubMed1997

Morphological study of pituitary tumorigenesis in transgenic mice induced by hybrid oncogene of the thyrotropin beta-subunit and the simian virus 40 large T-antigen.

We have created a transgenic mouse, TTP-1, generating anterior pituitary tumors by using the simian virus 40 (SV40) large T antigen gene and human thyrotropin beta-subunit gene. To examine characteristics of tumors, histological details were investigated using light and electron microscopies. The main tumor tissues, composed of small chromophobe cells, were located inferior to but clearly separated from the hypothalamus; however, neuron fibers probably derived from the hypothalamus were observed to invade some tumor tissues. Some differentiated endocrine cells occupied the caudal region of the tumor. Immunohistochemically, SV40 large T antigen was expressed in the cell nucleus of the undifferentiated cell area, whereas cells expressing several hormones were mainly distributed in the differentiated cell area. Electron microscopically, the undifferentiated cells were divided into 2 types; electron-dense and -lucent cells, the nuclei of which were composed of obscured nucleoli and many notable invaginations of the nuclear membrane. No intracellular microfilamentous structures were observed. Sometimes it was noted that cytoplasmic processes were connected with gap junctions. In the intercellular spaces, there were neuron fibrous and synapse-like structures. In the differentiated cell area, the cell membranes directly contacting other cells were relatively smooth, and many gap junctions were demonstrated. Secretory granules, which were round and less than 100 nm in diameter, were more electron dense in smaller cells than in larger cells. They were aligned just below the cell membrane. Immuno-electron microscopically, positive reactions for SV40 were observed in the nuclei of the undifferentiated cell area. In the differentiated cell area, most of the secretory granules were labeled by GH. TTP-1 transgenic mice should provide a valuable animal model for studying the pathogenesis of anterior pituitary tumors.

Animals↗

PubMed1997

Magnetic resonance imaging of hepatocellular carcinoma in Long-Evans cinnamon rats under a magnetic field of 7.05 T.

Magnetic resonance (MR) images of livers in 3-, 12- and 29-month-old Long-Evans Cinnamon(LEC) rats (male) were taken under a magnetic field of 7.05 T. MR images of sagittal and transversal sections were obtained in 1-mm-thick slices by T1-weighted and two-dimensional Fourier transformation techniques. The data matrix size was 256 phase-encoded steps. Each image was obtained through four acquisitions. Three-month-old rats gave MR images with low signal intensity over the liver probably due to the shorting of its T1 and T2 relaxation times. However, 12-month-old rats gave hyperintense regions around hepatic veins in right hepatic lobe, which was assigned to hepatocellular carcinoma. In 29-month-old rats, MR images with hyperintensity throughout the hepatic lobe were observed. These MR images, therefore, suggested that hepatocellular carcinoma in LEC rats developed from the restricted regions surrounding hepatic veins. In the present study, T1-weighted MR imaging under a magnetic field of 7.05 T was shown to be applicable to the diagnosis of hepatic cancer in LEC rats.

Animals↗

PubMed1996

Apoptosis and CD8-down-regulation in the thymus of chickens infected with Marek's disease virus.

Marek's disease virus (MDV)-infected chickens show thymic atrophy during the acute phase of infection. We examined whether the thymic atrophy by MDV-infection was mediated by apoptosis. Apoptosis-specific DNA ladderings were clearly observed in thymocytes one week after MDV-infection. Histological and flow cytometry studies revealed that immature CD4+ CD8+ thymocytes underwent apototic cell death. In addition, the expression level of CD8 molecules on both CD4(-)CD8+ and CD4+ CD8+ thymocyte populations was down-regulated in the infected chickens. These thymic changes might be involved in the pathogenesis of Marek's disease.

Animals↗

PubMed1996

Development of T-lymphocyte subpopulations in the postnatal chicken oviduct.

Postnatal development of t-cell subpopulations in the oviduct was investigated in the Dekalb strain of the White Leghorn chicken by using an immunohistochemical method. T-lymphocytes first infiltrated the oviduct at 5 weeks. The number of T cells peaked at 15 weeks in the magnum, isthmus and uterus, and at 19 weeks in the infundibulum and vagina. The epithelium of the oviduct contained both granular and agranular lymphocytes. TcR1+ cells were predominant in the epithelium, whereas TcR2+ cells were more numerous than TcR1+ cells in the lamina propria. TcR3+ cells were absent from the epithelium and were not numerous in the lamina propria. CT8+ cells, equivalent to CD8+ cells in mammals, were located both in the epithelium and in the lamina propria. The relative frequency of T-cell subpopulations was found to be higher in the vaginal part than in the other parts of the oviduct. These results suggest that the postnatal developmental changes of T-cell subpopulations depend on different anatomical regions of the oviduct and on the age of the chicken.

Animals↗

PubMed1996

Lymphocyte subpopulations in the mammary gland of the goat.

Mammary glands of pregnant, lactating and resting goats were studied by immunohistochemistry for lymphocyte subpopulations using a panel of monoclonal antibodies. All T lymphocyte subpopulations that may have a role in the immune response, CD2+, CD4+, CD8+ and gamma delta T cells and subsets, were present in the mammary gland and were noted to increase in number progressively during pregnancy, decrease significantly during lactation, and then moderately increase during the resting period. CD4+ cells, the predominant cell type in the mammary gland, were located mainly in the connective tissue, whereas CD2+, CD8+ and TcR1-N24+ cells were predominant in the intraepithelial areas. TcR1-N6+ cells were detected almost exclusively during pregnancy, being localized mainly in the connective tissue. Their proportion decreased markedly following parturition. Very few WC1-N3+ and -N4+ cells were detected in the mammary gland. It is suggested that the majority of gamma delta T lymphocytes in the mammary gland of the goat are CD2+ CD8+ WCl-, a distinctive subset from that of the WCl+ subset in peripheral blood.

Animals↗

PubMed1996

The effects of alpha-phenyl-tert-butyl nitrone (PBN) on copper-induced rat fulminant hepatitis with jaundice.

In the present study we demonstrated the protective effects of the spin-trapping agent alpha-phenyl-tert-butyl nitrone (PBN) against fulminant hepatitis with jaundice in LEC rats. In LEC rats an excess amount of copper is accumulated in the liver and causes hepatitis with severe jaundice. PBN was subcutaneously administered every 2 d at the concentration of 128 mg/kg, beginning with 13-week-old rats and continuing for 17 weeks. PBN prevented the loss of body weight, reduced death rate, and suppressed the increase in GTP and GOT values reflecting hepatic cell destruction. Ocular inspection also confirmed the suppressive effects of PBN on jaundice. In parallel with these phenomena, the amounts of thiobarbituric acid-reactive substances (TBARS) in livers of PBN-administered rats were found to be lower than those of non-PBN-administered rats. Little histological changes were observed in PBN-administered rats in comparison with non-PBN-administered rats. The protective effect of PBN on the formation of oxidative damage in liver DNA was observed but not so remarkable as that on lipid peroxidation. From these results, it was concluded that PBN had the liver-protective effects against fulminant hepatitis with jaundice. This suggested that free radicals play an important role in abnormally accumulated copper-induced liver injury and that PBN potentially has therapeutic value for the treatment of hepatitis.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed1996

Detection of coagulating gland renin by hybridohistochemistry.

To obtain evidence of renin-synthesizing cells in the murine coagulating gland (CG), CG renin mRNA was detected by hybridohistochemistry, as well as in vitro reverse transcriptase-polymerase chain reaction (RT-PCR) in intact, castrated and testosterone-treated C57BL/6 mice. Hybridohistochemistry using paraffin sections of the kidneys and the CGs for the detection of renin mRNA was performed with digoxigenin-labelled probes. Some paraffin sections were immunohistochemically stained for renin by the peroxidase-anti-peroxidase method. Total RNA was extracted, incubated by reverse transcriptase, and amplified by PCR. In the kidneys, the immunoreactivity and the positive signals of hybridohistochemistry using an antisense probe were restricted to the same juxtaglomerular cells. In the control and at 7 days after testosterone administration to castrated mice, both renin-immunoreactivity and -hybridoreactivity were expressed by the epithelial cells in the CGs, while, in the CGs of the castrated mice and 3 days after testosterone injection of castrated animals, neither renin-immunoreactivity nor -hybridoreactivity was detected in the epithelial cells. Using RT-PCR, renin mRNA from the mice in the control and 7 days after testosterone injection of castrated was amplified, whereas, in the castrated and the 3 days after testosterone injection of castrated groups, it was not detected. The data presented here provide additional evidence that CG renin is regulated by testosterone.

Animals↗

PubMed1996

Detection of transcripts of Marek's disease virus serotype 1 iCP4 homologue (MDV1 ICP4) by in situ hybridization.

Homologues of herpes simplex virus ICP4 are important genes for the activation of many herpesviruses. We detected transcripts of the Marek's disease virus serotype 1 homologue of ICP4 (MDV1 ICP4) by in situ hybridization (ISH). Using a digoxigenin-labeled-RNA (DIG-RNA) probe, MDV1 ICP4 transcripts were detected in c.a. 90% of MDV1-infected chicken embryo fibroblasts (CEF) cells when cytopathic effect was reached to 90% of the CEF cells and in 0.35% of MDCC-MSB-1 (MSB-1) cells, at a frequency similar to that for MD antigen-positive MSB-1 cells. Using the same in situ procedure, we detected abundant MDV1 ICP4 transcripts in the feather follicle epithelium (FFE) and some lymphoid cells in the liver, kidney and peripheral nerve of infected chickens. The subcellular localization of the transcripts appeared to vary: MSB-1 cells had them in the nucleus, infected CEF cells and FFE had them in the nucleus and cytoplasm, and lymphoid cells contained them in the cytoplasm. The MDV1 ICP4 transcripts were also detected in the FFE and lymphoid cells in the liver by reverse-transcriptase polymerase chain reaction (RT-PCR). Detection of MDV1 ICP4 transcripts by RT-PCR indicated the existance of MDV1 ICP4 transcripts-positive cells in these tissues. And these data suggested that DIG-RNA-ISH can detect MDV transcripts on paraffin sections and provide information about their subcellular localization.

Animals↗

PubMed1996

Cytolytic activity induced by intramuscular injection of plasmid DNA expressing the nucleocapsid protein of the JHM strain of mouse hepatitis virus into C57BL/6 mice.

We constructed plasmids expressing mRNA7 coding the nucleocapsid (N) protein of JHM strain of MHV (JHMV) under the control of Rous sarcoma virus (RSV) LTR or human elongation factor (EF) 1a promoter, referred to as pRSV-mRNA7 and pEF-mRNA7, respectively. Although only a slight level of cytolysis was observed by the spleen cells from C57BL/6 mice injected intramuscularly with pEF-mRNA7, the spleen cells from the mice administered with pRSV-mRNA7 showed a significant level of cytolytic activities against the cells expressing the viral N protein. The difference in the level of specific cytolysis might have been mainly due to a difference in the expression levels of the N protein in the muscles between the mice injected with pEF-mRNA7 and pRSV-mRNA7, since the specific activity of chloramphenicol acetyltransferase (CAT) in muscles from the mice injected with plasmid DNA expressing CAT gene directed by RSV LTR was significantly higher than that in those administered by the plasmid DNA directed by EF-1a promoter.

Animals↗

PubMed1996

Local renin-angiotensin system: especially in coagulating glands of mice.

It is well known that the renin-angiotensin system (RAS) is involved in the control of blood pressure. Recently, all or part of the components concerning the RAS have been reported to be synthesized and secreted outside of classical organs or tissues, at sites including the brain, pituitary and pineal glands, eye, heart, adrenal gland, testes, ovary, placenta, and coagulating glands. The functions and roles of these local RAS are not well known. In the present review, the author explains the history of the RAS, the circulating RAS and the existence of local RAS in multiple organs and tissues, discussing especially the function of coagulating gland renin. Renin protein, the triggering enzyme of the RAS, is distributed generally in certain fixed cells of several organs and tissues, exemplified by the gonadotrops in the pituitary glands and Leydig cells in the testis. Renin mRNA and its expressing cells can also be detected from the above cells as a whole. In some tissues, angiotensinogen-containing cells do not, however, correspond to its mRNA-expressing cells and potent activator angiotensin II-containing cells, as, for example, in the brain. These cases are explained by constitutive pathways of angiotensinogen processing. Coagulating gland renin, which the author is investigating vigorously, is the most recently discovered local renin, and represents significant subject for investigations. It is suggested that coagulating gland renin may play an unique function for sexual organs by exocrine mechanism.

Animals↗

PubMed1996

Expression of renin in coagulating glands.

The presence of an extrarenal or local reninangiotensin system has been noted in several tissues, although their functions have not yet been clarified. Renin from the coagulating gland (CG), is the most recently discovered local renin, and is a significant subject for investigation with histological and molecular biological techniques. Dot-like reactions for renin are detected immunohistochemically in the epithelial cells of CGs of the strains C57BL/6 mice. Excretory products of some terminal lumina are also found to be positive for renin. Colloidal gold particles, indicating the presence of renin, are detected in the lysosomal granules, in which they are especially located on the crystalline structure. They are also observed in the production of series of exocrine granules. At the apical region, both reninpositive exocrine and lysosomal granules are secreted by exocytosis. In the development, immunoreactivity for renin is first detected at 6 weeks after birth. After that time, the number of renin-containing cells gradually increase throughout the development. In adults, several patterns of renin immunoreactivity are demonstrated in almost all epithelial cells of CGs. At 4 weeks after castration, renin-containing cells in terminal ducts are decreased and remain at very low levels. After testosterone injection, the numerical value of renin-containing cells is high at 1 week. Finally, renin mRNA is detected in the CGs by Northern blot analysis and hybridohistochemistry. These findings suggest that renin is synthesized depending on testosterone, and released by exocrine secretion.

Animals↗