Biomedical subjects

Yoshie Yamamoto

Publications and source records attributed to Yoshie Yamamoto.

At least 19 recordsLinked to original sources

PubMed2006

Thymus-derived leukemia-lymphoma in mice transgenic for the Tax gene of human T-lymphotropic virus type I.

Adult T-cell leukemia-lymphoma (ATLL) is a group of T-cell malignancies caused by infection with human T-lymphotropic virus type I (HTLV-I). Although the pathogenesis of ATLL remains incompletely understood, the viral regulatory protein Tax is centrally involved in cellular transformation. Here we describe the generation of HTLV-I Tax transgenic mice using the Lck proximal promoter to restrict transgene expression to developing thymocytes. After prolonged latency periods, transgenic mice developed diffuse large-cell lymphomas and leukemia with clinical, pathological and immunological features characteristic of acute ATLL. Transgenic mice were functionally immunocompromised and they developed opportunistic infections. Fulminant disease also developed rapidly in SCID mice after engraftment of lymphomatous cells from transgenic mice. Flow cytometry showed that the cells were CD4(-) and CD8(-), but CD44(+), CD25(+) and cytoplasmic CD3(+). This phenotype is indicative of a thymus-derived pre-T-cell phenotype, and disease development was associated with the constitutive activation of NF-kappaB. Our model accurately reproduces human disease and will provide a tool for analysis of the molecular events in transformation and for the development of new therapeutics.

Animals↗

PubMed2006

Erythropoietin-producing cells in the liver of ICR-derived glomerulonephritis (ICGN) mice.

The ICR-derived glomerulonephritis (ICGN) mouse is an appropriate model for anemia associated with chronic renal disorder (CRD). Insufficient renal production of erythropoietin (EPO) induces the anemia associated with CRD. EPO mRNA is expressed in both kidneys and liver of progressing-stage ICGN mice. Hypoxic stimulation induced the EPO mRNA expression in the liver as well as in the kidneys of ICGN mice. The localization of EPO-producing cells in the liver remains controversial. Present study using an amplified in situ hybridization technique identified that nonparenchymal cells were the source of hepatic EPO production in ICGN mice under both normoxia and hypoxia.

Animals↗

PubMed2006

Transgene insertion pattern analysis using genomic walking in a transgenic mouse line.

A transgene mapping technique (Noguchi et al., Exp. Anim. 53:103-111, 2004) is described that can be used to analyze transgene integration patterns in transgenic mice. The technique was used to reveal that a transgenic mouse line (GM1-sy#116) harbored inverted and direct tandem repeats of both intact and partial pCAGGS-based transgenes in the G2 region of chromosome 1. This complicated concatenation of transgenes may have been caused by simple end-joining of DNA constructs fragmented by exposure to UV transillumination during gel-purification, and by nuclease digestion inside zygote pronuclei. The results suggest that care should be taken to avoid unwanted fragmentation during the preparation of vector constructs.

Animals↗

PubMed2005

Transforming growth factor-beta1 mediated up-regulation of lysyl oxidase in the kidneys of hereditary nephrotic mouse with chronic renal fibrosis.

Lysyl oxidase (LOX), an extracellular enzyme, plays a key role in the post-translational modification of collagens and elastin, catalyzing inter- and intra-crosslinking reactions. Because the crosslinked extracellular matrices (ECMs) are highly resistant to degradative enzymes, it is considered that the over-expression of LOX may cause severe fibrotic degeneration. In the present study, we addressed the role of LOX-mediated crosslinking in chronic renal tubulointerstitial fibrosis using an animal model of hereditary nephrotic syndrome, the Institute of Cancer Research (ICR)-derived glomerulonephritis (ICGN) mouse. Ribonuclease protection assay (RPA) revealed that LOX mRNA expression was up-regulated in the kidneys of ICGN mice as compared with control ICR mice. High-level expression of LOX and transforming growth factor (TGF)-beta1 (an up-regulator of LOX) mRNA was detected in tubular epithelial cells of ICGN mouse kidneys by in situ hybridization. Type-I and -III collagens, major substrates for LOX, were accumulated in tubulointerstitium of ICGN mouse kidneys. The present findings imply that TGF-beta1 up-regulates the production of LOX in tubular epithelial cells of ICGN mouse kidneys, and the excessive LOX acts on interstitial collagens and catalyzes crosslinking reactions. As a result, the highly crosslinked collagens induce an irreversible progression of chronic renal tubulointerstitial fibrosis in the kidneys of ICGN mice.

Animals↗

PubMed2005

Birth of offspring after transfer of Mongolian gerbil (Meriones unguiculatus) embryos cryopreserved by vitrification.

The Mongolian gerbil (Meriones unguiculatus) has been used as a laboratory species in many fields of research, including neurology, oncology, and parasitology. Although the cryopreservation of embryos has become a useful means to protect valuable genetic resources, its application to the Mongolian gerbil has not yet been reported. In this study, we investigated the in vitro and in vivo developmental competence of Mongolian gerbil embryos cryopreserved by vitrification. In vivo-fertilized embryos were vitrified on the day of collection using the ethylene glycol (EG)-based solutions EFS20 and EFS40, which contained 20% and 40% EG, respectively, in PB1 containing 30% (w/v) Ficoll 70 and 0.5 M sucrose. First, we compared one-step and two-step vitrification protocols. In the one-step method, the embryos were directly transferred into the vitrification solution (EFS40), whereas in the two-step method, the embryos were exposed serially to EFS20 and EFS40 and then vitrified. After liquefying (thawing), late two-cell embryos (collected on day 3) vitrified by the two-step method showed significantly better rates of in vitro development to the morula stage compared to those vitrified by the one-step method (65% vs. 5%, P < 0.0001). We then examined whether the same two-step method could be applied to early two-cell embryos (collected on day 2), four-cell embryos (day 4), morulae (day 5), and blastocysts (day 6). After liquefying, 87%-100% of the embryos were morphologically normal in all groups, and 23% and 96% developed to the compacted morula stage from early two- and four-cell embryos, respectively. After transfer into recipient females, 3% (4/123), 1% (1/102), 5% (4/73), and 10% (15/155) developed to full-term offspring from vitrified and liquefied early two-cell embryos, late two-cell embryos, morulae, and blastocysts, respectively. This demonstrates that Mongolian gerbil embryos can be safely cryopreserved using EG-based vitrification solutions.

Animals↗

PubMed2005

Effect of oral glucose administration on serum potassium concentration in hemodialysis patients.

BACKGROUND: Extrarenal potassium disposal is particularly critical in patients with end-stage renal disease. Exogenous insulin stimulates this disposal by enhancing potassium uptake into cells in hemodialysis (HD) patients and healthy subjects. However, the effect of physiological levels of endogenous insulin on this disposal in these patients or healthy subjects is unknown. METHODS: Effects of an oral glucose tolerance test (37.5, 75, and 150 g) on serum potassium levels were determined in 13 HD patients and 7 healthy controls. Serum potassium and insulin levels and plasma aldosterone and epinephrine levels were measured before and after glucose loads. RESULTS: In HD patients and controls, serum insulin levels increased to a similar magnitude in parallel with increased serum glucose levels, but serum potassium levels decreased significantly only in HD patients. In HD patients, plasma aldosterone or epinephrine levels were not changed significantly after a glucose load. In HD patients, the decrease in serum potassium levels was dependent on the increase in serum insulin levels and was more prominent when 150 g of glucose was administered. In HD patients, the decrease in serum potassium levels correlated negatively (r = -0.45; P < 0.001) with the increase in serum insulin levels, and maximal decrease in serum potassium levels correlated negatively (r = -0.54; P < 0.001) with maximal increase in serum insulin levels. CONCLUSION: Endogenous production of physiological concentrations of insulin in response to exogenous glucose administration decreases serum potassium levels only in HD patients, independently of plasma aldosterone and epinephrine levels.

Administration, Oral↗

PubMed2005

Decreased expression of matrix metalloproteinases and tissue inhibitors of metalloproteinase in the kidneys of hereditary nephrotic (ICGN) mice.

Matrix metalloporoteinases (MMPs), which are dominantly regulated by tissue inhibitors of metalloproteinase (TIMPs), play important roles in extracellular matrix (ECM) degradation and are involved in the progression of kidney diseases. In glomeruli and tubulointerstitum of hereditary nephrotic (ICR-derived glomerulonephritis: ICGN) mouse kidneys, hyper-accumulation of ECM components occurred, and MMP activity decreased. In the present study, because lower levels of MMP activity may contribute to the progression of renal fibrosis in ICGN mice, Western blotting analysis and immunohistochemical staining for MMPs and TIMPs were performed to verify the expression levels of these proteins. Levels of MMP-2, MMP-9, MT1-MMP, TIMP-1 and TIMP-2 in the kidneys were decreased in ICGN mice in comparison with normal ICR mice. These results indicate that small amounts and low levels of activity of MMPs cause the progression of renal fibrosis in ICGN mice.

Animals↗

PubMed2005

Dysfunction of erythropoietin-producing interstitial cells in the kidneys of ICR-derived glomerulonephritis (ICGN) mice.

Anemia is a major secondary symptom in chronic renal disorder (CRD), but the precise cause of insufficient production of erythropoietin (EPO) remains unclear owing to the controversial localization of EPO-producing cells in the kidneys. The ICR-derived glomerulonephritis (ICGN) mouse, a new hereditary nephrotic mouse, is an appropriate model of anemia associated with CRD. By using an amplified in situ hybridization technique, we detected and counted the renal EPO-producing cells under both normoxic and hypoxic conditions. The expression levels of renal EPO mRNA were quantified and oxygen gradients were also assessed immunohistochemically. Amplified in situ hybridization clarified that EPO-producing cells were peritubular interstitial cells in the middle region of renal cortex in both ICR and ICGN mice. Hypoxia (7% O2) induced low oxygen tension in proximal tubular epithelial cells of renal cortex, and increased the expression of EPO mRNA and the number of EPO-producing cells in both ICR and ICGN mice. However, hypoxia did not increase the serum EPO levels in ICGN mice. The ICGN mouse is a good model for anemia associated with CRD, and the suppression of EPO protein production in the renal EPO-producing cells is considered to be a potential cause of anemia associated with CRD.

Analysis of Variance↗

PubMed2004

Sequence analysis of cDNA encoding follicle-stimulating hormone and luteinizing hormone beta-subunits in the Mastomys (Praomys coucha).

To examine the molecular basis of efficient superovulation in the Mastomys (Praomys coucha), the cDNA sequences of the follicle-stimulating hormone (FSH) and luteinizing hormone (LH) beta-subunits were determined and compared with those of other mammals. FSHbeta and LHbeta cDNAs were 1606 and 513 bp long, respectively, from the 5'-ends to the putative polyA sites. The deduced sequences of the FSHbeta and LHbeta precursor proteins were 130 and 141 amino acids in length, respectively. The amino acid sequences of both mastomys hormone subunits showed overall similarity to those of other rodents. In particular, the N-terminus of the FSHbeta precursor protein is of the MM-type, like those of mice and rats, which suggests that the MM-type is characteristic of the subfamily Murinae. As we reported earlier for the Mongolian gerbil, the use of hCG for superovulation of mastomys might need to be re-evaluated, due to the low homology between hCG and rodent LH sequences.

Amino Acid Sequence↗

PubMed2004

Sequence analysis of cDNA encoding follicle-stimulating hormone and luteinizing hormone beta-subunits in the Mongolian gerbil (Meriones unguiculatus).

To examine the molecular basis for efficient superovulation in the Mongolian gerbil, the cDNA sequences of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) beta-subunits were determined and compared with those of other mammals. FSHbeta and LHbeta cDNAs were 1637 and 507bp long, respectively, from the 5'-end to putative polyA sites. The deduced sequences of the FSHbeta and LHbeta precursor proteins were 129 and 141 amino acids in length, respectively. The amino acid sequences of both Mongolian gerbil hormone subunits showed overall similarity to those of other rodents, confirming that the combination of equine chorionic gonadotropin (eCG) and human chorionic gonadotropin (hCG) should be effective for induction of superovulation in Mongolian gerbils, as in mice and rats. However, the use of hCG might need to be re-evaluated owing to its low homology to rodent LH.

Amino Acid Sequence↗

PubMed2004

Tissue-specific distribution of donor mitochondrial DNA in cloned mice produced by somatic cell nuclear transfer.

Highly diverse results have been reported for mitochondrial DNA (mtDNA) hetero-plasmy in nuclear-transferred farm animals. In this study, we cloned genetically defined mice and investigated donor mtDNA inheritance following somatic cell cloning. Polymerase chain reaction (PCR) analysis with primers that were specific for either the recipient oocytes or donor cells revealed that the donor mtDNA coexisted with the recipient mtDNA in the brain, liver, kidney, and tail tissues of 96% (24/25) of the adult clones. When the proportion of donor mtDNA in each tissue was measured by allele-specific quantitative PCR and subjected to ANOVA analysis, a tissue-specific mtDNA segregation pattern (P < 0.05) was observed, with the liver containing the highest proportion of donor mtDNA. Therefore, the donor mtDNA was inherited consistently by the cloned offspring, whereas donor mtDNA segregation was not neutral, which is in accordance with previous notions about tissue-specific nuclear control of mtDNA segregation.

Animals↗

PubMed2004

Changes in the localization of type I, III and IV collagen mRNAs in the kidneys of hereditary nephritic (ICGN) mice with renal fibrosis.

Renal fibrotic change, extreme accumulation of extracellular matrix (ECM) components in glomeruli and tubulointerstitum, is one of the characteristic features of ICR-derived glomerulonephritis (ICGN) mice. Decreased degradation of ECMs by matrixmetalloproteinases was demonstrated in kidneys of ICGN mice. To determine the balance between production and degradation of ECMs in kidneys of ICGN mice, we examined expression of mRNAs of ECMs in those. To demonstrate the localization of type I, III and IV collagen mRNAs in kidney sections of ICGN and control ICR mice, in situ hybridization using digoxigenin-labeled oligonucleotide antisense probes for procollagen-alpha(1) (I), -alpha(1) (III) and -alpha(1) (IV) mRNAs, respectively, was performed. Negative or trace expressions of type I and III collagen mRNAs were observed in the kidneys of control mice, but stronger expressions of those were seen in glomeruli and injured renal tubules of the kidneys of ICGN mice. Moderate expression of type IV collagen mRNA was demonstrated in a part of glomeruli and renal tubules of both control and ICGN mice, and no remarkable difference was seen between them. Severe renal fibrosis, extreme accumulation of interstitial type I and III collagens is caused by increased production and decreased degradation in the kidneys of ICGN mice. Thus, the profiles of metabolism between interstitial and membranous collagens may be different in the kidneys of ICGN mice, and excessive production of interstitial collagens may be the dominant cause of renal disease in them.

Animals↗

PubMed2004

Anemia with chronic renal disorder and disrupted metabolism of erythropoietin in ICR-derived glomerulonephritis (ICGN) mice.

The ICR-derived glomerulonephritis (ICGN) mouse, a new inbred mouse strain with a hereditary nephrotic syndrome, is considered to be a good model of human idiopathic nephrotic syndrome and notably exhibits proteinuria and hypoproteinemia from the neonatal stage. In chronic renal disorder (CRD), anemia is a major subsequent symptom (renal anemia). The precise cause of renal anemia remains unclear, primarily owing to the lack of appropriate spontaneous animal models for CRD. To establish adequate animal models for anemia with CRD, we examined the hematological-biochemical properties and histopathological characteristics. With the deterioration of renal function, ICGN mice developed a normochromic and normocytic anemia, and exhibited normochromic and microcytic at the terminal stage. The expression of erythropoietin (EPO) mRNA both in the kidneys and liver and the EPO leak into the urine were observed in ICGN mice, indicating a disrupted metabolism of EPO in ICGN mice. In addition, a lack of iron induced by the hemolysis in the spleen and the leak of transferrin into urine as proteinuria aggravated the anemic condition. In conclusion, the ICGN mouse is a good model for anemia with CRD.

Analysis of Variance↗

PubMed2004

Improvement of anemia associated with chronic renal failure by recombinant human erythropoietin treatment in ICR-derived glomerulonephritis (ICGN) mice.

The ICR-derived glomerulonephritis (ICGN) mouse, a novel inbred mouse strain with a hereditary nephrotic syndrome, develops severe anemia associated with chronic renal failure. To reveal the pathogenic mechanism of anemia in ICGN mice, we subcutaneously administered recombinant human erythropoietin (rhEPO; 5 IU/mouse/day) or saline for 5 days to ICGN mice. In terminal-stage ICGN mice with severe anemia, rhEPO significantly increased hematocrit (Ht), red blood cells (RBC) and hemoglobin levels. Endogenous EPO levels in peripheral blood were reduced by rhEPO injection. No histopathological changes in bone marrow and kidneys were induced by rhEPO injection. Insufficiency of EPO may cause anemia in ICGN mice.

Anemia↗

PubMed2004

Chromosomal mapping and zygosity check of transgenes based on flanking genome sequences determined by genomic walking.

Transgenes can affect transgenic mice via transgene expression or via the so-called positional effect. DNA sequences can be localized in chromosomes using recently established mouse genomic databases. In this study, we describe a chromosomal mapping method that uses the genomic walking technique to analyze genomic sequences that flank transgenes, in combination with mouse genome database searches. Genomic DNA was collected from two transgenic mouse lines harboring pCAGGS-based transgenes, and adaptor-ligated, enzyme restricted genomic libraries for each mouse line were constructed. Flanking sequences were determined by sequencing amplicons obtained by PCR amplification of genomic libraries with transgene-specific and adaptor primers. The insertion positions of the transgenes were located by BLAST searches of the Ensembl genome database using the flanking sequences of the transgenes, and the transgenes of the two transgenic mouse lines were mapped onto chromosomes 11 and 3. In addition, flanking sequence information was used to construct flanking primers for a zygosity check. The zygosity (homozygous transgenic, hemizygous transgenic and non-transgenic) of animals could be identified by differential band formation in PCR analyses with the flanking primers. These methods should prove useful for genetic quality control of transgenic animals, even though the mode of transgene integration and the specificity of flanking sequences needs to be taken into account.

5' Flanking Region↗

PubMed2003

Chemical chaperone therapy for brain pathology in G(M1)-gangliosidosis.

We synthesized a galactose derivative, N-octyl-4-epi-beta-valienamine (NOEV), for a molecular therapy (chemical chaperone therapy) of a human neurogenetic disease, beta-galactosidosis (GM1-gangliosidosis and Morquio B disease). It is a potent inhibitor of lysosomal beta-galactosidase in vitro. Addition of NOEV in the culture medium restored mutant enzyme activity in cultured human or murine fibroblasts at low intracellular concentrations, resulting in a marked decrease of intracellular substrate storage. Short-term oral administration of NOEV to a model mouse of juvenile GM1-gangliosidosis, expressing a mutant enzyme protein R201C, resulted in significant enhancement of the enzyme activity in the brain and other tissues. Immunohistochemical stain revealed a decrease in the amount of GM1 and GA1 in neuronal cells in the fronto-temporal cerebral cortex and brainstem. However, mass biochemical analysis did not show the substrate reduction observed histochemically in these limited areas in the brain probably because of the brief duration of this investigation. Chemical chaperone therapy may be useful for certain patients with beta-galactosidosis and potentially other lysosomal storage diseases with central nervous system involvement.

Animals↗

PubMed2003

Effects of donor cell type and genotype on the efficiency of mouse somatic cell cloning.

Although it is widely assumed that the cell type and genotype of the donor cell affect the efficiency of somatic cell cloning, little systematic analysis has been done to verify this assumption. The present study was undertaken to examine whether donor cell type, donor genotype, or a combination thereof increased the efficiency of mouse cloning. Initially we assessed the developmental ability of embryos that were cloned from cumulus or immature Sertoli cells with six different genotypes (i.e., 2 x 6 factorial). Significantly better cleavage rates were obtained with cumulus cells than with Sertoli cells (P < 0.005, two-way ANOVA), which probably was due to the superior cell-cycle synchrony of cumulus cells at G0/G1. After embryo transfer, there was a significant effect of cell type on the birth rate, with Sertoli cells giving the better result (P < 0.005). Furthermore, there was a significant interaction (P < 0.05) between the cell type and genotype, which indicates that cloning efficiency is determined by a combination of these two factors. The highest mean birth rate (10.8 +/- 2.1%) was obtained with (B6 x 129)F1 Sertoli cells. In the second series of experiments, we examined whether the developmental ability of clones with the wild-type genotype (JF1) was improved when combined with the 129 genotype. Normal pups were cloned from cumulus and immature Sertoli cells of the (129 x JF1)F1 and (JF1 x 129)F1 genotypes, whereas no pups were born from cells with the (B6 x JF1)F1 genotype. The present study clearly demonstrates that the efficiency of somatic cell cloning, and in particular fetal survival after embryo transfer, may be improved significantly by choosing the appropriate combinations of cell type and genotype.

Animals↗

PubMed2003

Optimization of superovulation induction by human menopausal gonadotropin in guinea pigs based on follicular waves and FSH-receptor homologies.

The guinea pig represents an excellent animal model for the study of reproduction in humans and most domestic animals because unlike the mouse and rat, it undergoes a complete estrous cycle. In this study, we investigated the availability of ovarian oocytes during the estrous cycle, and the follicle stimulating hormone (FSH) receptor (FSH-R) homologies between guinea pigs and other species, in order to identify an effective gonadotropin and optimal time-of-application for the induction of superovulation in the guinea pig. The number of collectable ovarian oocytes showed biphasic changes with peaks at the midluteal and pre-ovulatory stages. On the other hand, the number of oocytes that matured in vitro remained constant ( approximately 10 oocytes) until day 14 post-ovulation and increased thereafter. The deduced amino acid sequence of the guinea pig FSH-R showed greater similarity to the primate FSH-R than to the rodent FSH-R, which suggests that commercially available human menopausal gonadotropin (hMG) may be a better inducer of superovulation in guinea pigs. Indeed, significantly more oocytes (5.4 +/- 1.6, range 0-17, n = 10) were obtained from hMG-treated guinea pigs at the pre-ovulatory stage than during spontaneous ovulation (3.6 +/- 0.1, n = 96; P < 0.05), whereas guinea pigs that received hMG at the midluteal stage (n = 3) did not ovulate. These results indicate that hMG is an effective, albeit stage-dependent, inducer of superovulation in the guinea pig, and that FSH-R homologies should be taken into account when choosing hormones for superovulation.

Amino Acid Sequence↗