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Biomedical subjects

Y Tsunoda

Publications and source records attributed to Y Tsunoda.

At least 37 records · Page 2Linked to original sources

Developmental potential of cumulus cell-derived culture frozen in a quiescent state after nucleus transfer.

An efficient method for freezing donor cells is necessary when using nucleus transfer of somatic cells for large-scale cloning. In the present study, we developed a method for freezing and thawing bovine cumulus cell-derived cultured cells to be used as nucleus donors. Cumulus cells were obtained from ovaries of living and slaughtered bovine and cultured in vitro. Cumulus cell-derived cultured cells were serum-starved for several days to induce a quiescent state and then frozen at -70 degrees C for at least 2 d. Immediately thereafter or 2 h after thawing, the cells were used as donor cells for nuclear transfer without additional in vitro culture. The fusion rate with recipient cytoplasts was not affected by the cumulus cell source (slaughtered or living) or time after thawing (0 and 2 h). The cleavage rate of frozen-thawed cumulus cell-derived cultured cells from slaughtered cows immediately after thawing (0 h) was highest (97%) and was significantly higher than that of controls (85%) or cells transferred 2 h after thawing (85%). There were no significant differences among any of the groups in the potential of the nuclear transfer embryos to develop into blastocysts (34 vs 44 and 44%, 39 vs 45 and 46%). Thus, storage of bovine cumulus cell-derived cultured cells in the quiescent state at -70 degrees C is effective and might be useful and convenient for large-scale cloning. The maximum storage periods and developmental potential of embryos after such nucleus transfers requires further examination.

Animals↗

Involvement of phosphoinositide 3-kinase and its association with pp60src in cholecystokinin-stimulated pancreatic acinar cells.

Phosphoinositide 3-kinase (PI3K) is a lipid kinase which phosphorylates the D3 position of the phosphoinositide derivatives and is known to be activated by a host of protein tyrosine kinases. PI3K has been demonstrated to play an important role in mitogenesis and cell transformation in several cell systems. However, the functional roles of PI3K in pancreatic acinar cells remain to be determined. The objective of this study was to identify and characterize the PI3K pathway and its relation to other non-receptor protein tyrosine kinases in mediating signal transduction of pancreatic acinar cells. Intact acini isolated from the rat pancreas were incubated with or without cholecystokinin octapeptide (CCK-8). A Triton X-100-soluble and 10000 rpm supernatant of the cell sonicates was used for immunoprecipitation and Western immunoblotting. When a monoclonal anti-phosphotyrosine antibody (clone 4G10) was used, two major tyrosine-phosphorylated bands were observed at the location of p85 and p60. CCK (10 pM and 10 nM) significantly enhanced the tyrosine phosphorylation of these two bands. Furthermore, when a monoclonal anti-PI3K antibody (clone UB93-3) which recognizes the N-terminal SH2 domain of the p85 regulatory subunit of PI3K was used, CCK (10 pM-10 nM) dose-dependently increased the amount of the immunodetectable PI3K band with a peak occurring at 5 min. The increase in the immunodetectable PI3K band elicited by CCK did not require the presence of extracellular Ca2+. The pp60src inhibitor, herbimycin A (6 microM), and the PI3K inhibitor, wortmannin (6 microM), both decreased intensities of the PI3K band elicited by CCK. Herbimycin A abolished phosphotransferase activities of the Src kinase following stimulation with CCK, whereas wortmannin had no effect, suggesting that Src is an upstream regulator of PI3K. Wortmannin (3-6 microM) abolished CCK-stimulated pancreatic amylase secretion. Immunoprecipitation studies using an anti-Src antibody (clone CD11) or PI3K antibody in conjunction with the anti-phosphotyrosine antibody showed that, in response to CCK, tyrosine phosphorylations of Src and PI3K were enhanced at the location of p60 and p85, respectively. Src was co-immunoprecipitated with PI3K following stimulation with CCK, suggesting that pp60src forms an immunocomplex with PI3K via the N-SH2 domain of the p85 regulatory subunit. Thus PI3K and its association with Src appear to be involved in mediating CCK-stimulated pancreatic exocytosis.

Amylases↗

Effects of long-term treatment with nonselective endothelin receptor antagonist, TAK-044, on remodeling of cardiovascular system with sustained volume overload.

To assess the role of endothelin-1 (ET-1) on cardiovascular remodeling, nonselective endothelin-receptor antagonist TAK-044 was administered for the long term to rabbits with or without arteriovenous (A-V) shunt formation. Six weeks after sham operation (n = 12) or carotid-jugular shunt formation (n = 21), TAK-044 (30 mg/day) or saline was infused subcutaneously using osmotic mini pumps for another 6 weeks. Twelve weeks after operation, left ventricular (LV) diameter was enlarged with the presence of an A-V shunt; however, the levels of LV diameter and arterial pressure or the postmortem weight of LVs of shunt rabbits were similar between saline and TAK-044 groups. A linear relation of the luminal diameter and the medial cross-sectional area of the left and right carotid arteries was similar between shunt + saline and shunt + TAK-044 groups. In saline groups, myocardial ET-1 levels were higher in shunt than in sham rabbits (217+/-22 vs. 136+/-19 pg/g tissue; p < 0.01 between rabbit groups) without changes in plasma ET-1 concentrations during saline infusion for 6 weeks. Differences in plasma ET-1 levels before and 6 weeks after the administration of TAK-044 were 0.32+/-0.78 and 0.16+/-0.28 pg/ml (NS between periods) in shunt and sham groups, respectively. In TAK-044 groups, myocardial ET-I levels 12 weeks after operation were similarly lower in both sham (105+/-7.4 pg/g tissue) and shunt rabbits (126+/-9.2 pg/g tissue) than in those with saline administration; however, the plasma ET-1 concentrations were increased significantly 6 weeks after TAK-044 administration by 5.0+/-0.6-fold and 3.5 +/-0.3-fold (p < 0.01) of the levels 6 weeks after operation in shunt and sham groups (NS between groups), respectively. Accordingly, myocardial but not plasma ET-1 levels were increased by a long-term burden of volume overload and were attenuated by a long-term administration of TAK-044 without altering drastically the hemodynamics or vascular remodeling. These results suggest that endogenous ET-1 does not play a major role in the compensatory stage of cardiovascular remodeling in the present volume-overload model.

Animals↗

Cloning of calves from various somatic cell types of male and female adult, newborn and fetal cows.

Twenty-four calves were cloned from six somatic cell types of female and male adult, newborn and fetal cows. The clones were derived from female cumulus (n = 3), oviduct (n = 2) and uterine (n = 2) cells, female and male skin cells (n = 10), and male ear (n = 5) and liver (n = 2) cells. On the basis of the number of cloned embryos transferred (n = 172) to surrogate cows, the overall rate of success was 14%, but based on the number of surrogate mothers that became pregnant (n = 50), the success rate was 48%. Cell nuclei from uterus, ear and liver cells, which have not been tested previously, developed into newborn calves after nuclear transfer into enucleated oocytes. To date, seven female and six male calves have survived: six of the females were from adult cells (cumulus (n = 3), oviduct (n = 2) and skin (n = 1) cells) and one was from newborn skin cells, whereas the male calves were derived from adult ear cells (n = 3), newborn liver and skin cells (n = 2), and fetal cells (n = 1). Clones derived from adult cells frequently aborted in the later stages of pregnancy and calves developing to term showed a higher number of abnormalities than did those derived from newborn or fetal cells. The telomeric DNA lengths in the ear cells of three male calves cloned from the ear cells of a bull aged 10 years were similar to those of the original bull. However, the telomeric DNA lengths from the white blood cells of the clones, although similar to those in an age-matched control, were shorter than those of the original bull, which indicates that telomeric shortening varies among tissues.

Abortion, Spontaneous↗

Induction of pluripotency by injection of mouse trophectoderm cell nuclei into blastocysts following transplantation into enucleated oocytes.

Pluripotency of mouse trophectoderm (TE) cells was examined using a nuclear transfer technique. We transferred a TE cell to an enucleated oocyte and cultured the reconstituted oocyte to be blastocyst stage. Then a portion of the inner cell mass (ICM) isolated from the TE-origin blastocyst was injected into the cavity of a fertilized blastocyst to produce a chimeric embryo, which was transferred to a recipient female. Of 319 oocytes reconstituted with TE cells, 263 (82.4%) had a single nucleus (1PN), 3 (0.9%) had 2 nuclei (2PN) and 53 (16.6%) had a nucleus with a polar body (1PN1PB). Although the oocytes with 1PN and 2PN developed to blastocysts (81 of 263, 30.8% and 1 of 3, respectively), only those with 1PN were used to produce chimeric blastocysts. After the transfer of chimeric embryos to recipient females, 7 (28%) of 25 conceptuses analyzed at midgestation showed chimerism. Of those 5 (71%), 6 (86%) and 4 (57%) chimeric conceptuses showed distribution of donor nuclei in the fetus, membrane and placenta, and the distributions were 10 to 65, 10 to 50 and 10 to 15%, respectively. Of the 23 young obtained, 7 (30%; 2 males and 5 females) were coat color chimeras. The contributions of donor nuclei were detected in the brain, lung, heart, liver, kidney, testis, ovary and blood. Each coat-color chimeric mouse was mated with CD-1 male or female mice, but no germ line chimera was obtained. When ICM cells were used as the control nuclear donor, the contribution was equivalent to those of TE cells. In conclusion, pluripotency of mouse TE cells on a somatic line was induced, and chimeric young were obtained using a nuclear transplantation technique.

Animals↗

Distinct characteristics of receptor-operated Ca2+ influx and refilling in pancreatic acinar cells.

Ca2+ influx from the extracellular space in nonexcitable cells occurs via receptor-operated and refilling processes. However, they showed different characteristics with respect to the Mn2+ permeability, depletion of intracellular Ca2+ stores, and sensitivity to the K+ ionophore valinomycin in rat pancreatic acinar cells. While Mn2+ did not enter into the cells during the refilling phase, the opposite was true in receptor-operated Ca2+ influx (ROCI) evoked by carbachol (CCh). ROCI occurred in the absence of intracellular Ca2+ release from the stores. Valinomycin abolished the second response of Ca2+ elicited by CCh, whereas it had no effect on ROCI. These observations suggest that receptor-operated Ca2+ channels (ROCCs) and refilling channels may be different in rat pancreatic acinar cells.

Animals↗

High-affinity cholecystokinin type A receptor/cytosolic phospholipase A2 pathways mediate Ca2+ oscillations via a positive feedback regulation by calmodulin kinase in pancreatic acini.

In rat pancreatic acini, we previously demonstrated that depending on the agonist used, activation of cholecystokinin type A (CCKA) receptor (CCK-AR) results in the differential involvement of the cytosolic phospholipase A2 (cPLA2), phospholipase Cbeta1 (PLCbeta1) and Src/protein tyrosine kinase (PTK) pathways. The high-affinity CCK-AR appears to be coupled to the Gbeta/cPLA2/arachidonic acid (AA) cascade in mediating Ca2+ oscillations. The low-affinity CCK-AR is coupled to both the Galphaq/11/PLCbeta1/inositol 1,4,5-trisphosphate (IP3) to evoke intracellular Ca2+ release and the Src/PTK pathway to mediate extracellular Ca2+ influx. The objectives of this study were to provide evidence that cPLA2 is present in pancreatic acini and to evaluate the possibility that its activation results in Ca2+ oscillations and amylase secretion. Furthermore, we investigated the mechanism of Ca2+ oscillations mediated by the high-affinity CCK-AR. In rat pancreatic acini, immunoprecipitation studies using an anti-cPLA2 monoclonal antibody, demonstrated a cPLA2 band at the location of 110 kDa. A selective inhibitor of cPLA2, AACOCF3 (100 microM), inhibited production of AA metabolites, Ca2+ oscillations and amylase secretion elicited by the high-affinity CCK-AR agonist, CCK-OPE (10-1000 nM). In addition, through the repetitive release of intracellular Ca2+, CCK-OPE enhanced phosphotransferase activities of Ca2+/calmodulin-dependent protein kinase type IV (CaMK IV), which were inhibited by AACOCF3. The CaMK inhibitor, K252-a (1-3 microM), also abolished basal and CCK-OPE-stimulated CaMK IV activities. The CaM inhibitor, W-7 (100 microM), and K252-a inhibited Ca2+ oscillations and amylase secretion evoked by CCK-OPE without affecting the AA formation. Therefore, it appears that Ca2+ oscillations elicited by the high-affinity CCK-AR/Gbeta/cPLA2/AA pathway activate CaMK IV. Activated CaMK, in turn, regulates Ca2+ oscillations through a positive feedback mechanism to mediate pancreatic exocytosis.

Affinity Labels↗

Developmental potential of mouse follicular epithelial cells and cumulus cells after nuclear transfer.

The developmental potential after nuclear transfer of mouse follicular epithelial cells cultured in vitro was examined. Follicular epithelial cells surrounding growing oocytes (type 5, diameter of oocytes, 62.6 +/- 5.9 microm; n = 14) were obtained from ovaries of adult mice. Before nuclear transfer, cells were cultured for several passages and subjected to serum starvation for several days. When the nuclear-transfer oocytes were at the 2-cell stage, serial nuclear transfer was performed. Additionally, cumulus cells surrounding ovulated oocytes were used as nuclear donors, with or without thermal stimulation (from -25 degrees C to 60 degrees C for 10 min) before nuclear transfer. Nuclear-transfer oocytes with follicular epithelial cells developed into blastocysts (34%) after serial nuclear transfer, and 4 living fetuses on Day 10.5 (25%, 16 transferred) and 1 dead fetus on Day 19.5 of pregnancy (3%, 30 transferred) were obtained after transfer to recipients. Although blastocysts (20%) were obtained after serial nuclear transfer of cumulus cells, only one implantation site without a fetus was observed on Day 10.5 of pregnancy. Thermal stimulation of cumulus cells before nuclear transfer did not enhance the ability to develop into fetuses or blastocysts.

Animals↗

Improvement of renal dysfunction in dogs with endotoxemia by a nonselective endothelin receptor antagonist.

OBJECTIVES: During endotoxemia, there is a marked and intractable decrease in systemic blood pressure, as well as profound vasoconstriction of the renal artery, thereby leading to septic shock and acute renal failure. The purpose of this study was to elucidate the effect of endothelin-1, a potent endothelium-derived vasoconstrictor peptide, on the hemodynamic and renal vascular changes seen in endotoxemia. DESIGN: Prospective, comparative, experimental study. SETTING: Laboratory at a university hospital. SUBJECTS: Thirty-two male mongrel dogs (12.1+/-0.4 kg) under pentobarbital anesthesia. INTERVENTIONS: Four groups of animals were studied: a) the lipopolysaccharide (LPS) group (n = 10), which received LPS (250 ng/kg/min for 2 hrs); b) the TAK-044 (a nonselective endothelinA/ endothelinB receptor antagonist) plus LPS group (n = 12), which received a bolus of TAK-044 (5 mg/kg) 0.5 hr before the start of LPS infusion; c) the TAK-044 plus vehicle group (n = 5), which received the same dose of TAK-044 0.5 hr before the start of vehicle infusion; and d) the control group (n = 5), which received only vehicle infusion. MEASUREMENTS AND MAIN RESULTS: Changes in systemic and renal hemodynamics, blood gas, and renal function were measured at baseline, and at 0.5, 1, 2, 3, and 4 hrs. Infusion of LPS resulted in significant decreases in mean arterial pressure, arterial pH, Pao2, base excess, urine volume, renal blood flow, creatinine clearance, and urine osmolality. The administration of TAK-044 before LPS infusion did not affect the LPS-induced hypotension. In contrast, the receptor antagonist prevented LPS-induced metabolic acidosis and hypoxemia, and improved LPS-induced decreases in urine volume, renal blood flow, creatinine clearance, and urine osmolality, whereas TAK-044 or vehicle administered alone resulted in no significant hemodynamic or blood gas changes. Plasma endothelin-1 concentrations significantly increased after LPS infusion, with or without TAK-044. CONCLUSIONS: The present study suggests that endothelin-1 plays an important role in the impaired renal hemodynamics and renal function associated with endotoxemia, and that endothelin receptor antagonists may be useful as therapeutic agents for acute renal failure during endotoxemia.

Acute Kidney Injury↗

Diazepam-binding inhibitor33-50 elicits Ca2+ oscillation and CCK secretion in STC-1 cells via L-type Ca2+ channels.

We recently isolated and characterized 86-amino acid CCK-releasing peptide from porcine intestinal mucosa. The sequence of this peptide is identical to that of porcine diazepam-binding inhibitor (DBI). Intraduodenal administration of DBI stimulates the CCK release and elicits pancreatic secretion in rats. In this study we utilized a murine tumor cell line (STC-1 cells) that contains CCK to examine if DBI directly acts on these cells to stimulate CCK release. We investigated the cellular mechanisms responsible for this action. We showed that DBI33-50, a biologically active fragment of DBI1-86, significantly stimulated CCK secretion in STC-1 cells. This action was abolished by Ca2+-free medium. The mean basal intracellular Ca2+ concentration ([Ca2+]i) was 52 nM in fura 2-loaded STC-1 cells. DBI33-50 (1-1,000 nM) elicited Ca2+ oscillations; DBI33-50 (10 nM) increased the oscillation frequency to 5 cycles/10 min and elicited a net [Ca2+]i increase (peak - basal) to 157 nM. In contrast, bombesin and forskolin caused an initial transient [Ca2+]i followed by a small sustained [Ca2+]i plateau. Withdrawal of extracellular Ca2+ abolished Ca2+ oscillations stimulated by DBI33-50. L-type Ca2+ channel blockers nifedipine and diltiazem (3-10 microM) markedly attenuated DBI-stimulated Ca2+ oscillations. In other cell types L-type Ca2+ channels are activated by cAMP-protein kinase A. DBI33-50 failed to stimulate cAMP formation in STC-1 cells. Similarly, DBI33-50 had no effect on myo-inositol 1,4, 5-trisphosphate concentration ([IP3]), whereas bombesin caused an eightfold increase in [IP3] over basal. In addition, inhibitors of phospholipase C (U-73122), phospholipase A2 (ONO-RS-082), and protein tyrosine kinase (genistein) did not alter the Ca2+ oscillations elicited by DBI33-50. It appears that DBI33-50 acts directly on STC-1 cells to elicit Ca2+ oscillations via the voltage-dependent L-type Ca2+ channels, resulting in the secretion of CCK. Mediation of this action is by intracellular mechanisms independent of the traditional signal transduction pathways, including phospholipase C, phospholipase A2, protein tyrosine kinase, and cAMP systems.

8-Bromo Cyclic Adenosine Monophosphate↗

Involvement of RhoA and its interaction with protein kinase C and Src in CCK-stimulated pancreatic acini.

We evaluated intracellular pathways responsible for the activation of the small GTP-binding protein Rho p21 in rat pancreatic acini. Intact acini were incubated with or without CCK and carbachol, and Triton X-100-soluble and crude microsomes were used for Western immunoblotting. When a RhoA-specific antibody was used, a single band at the location of 21 kDa was detected. CCK (10 pM-10 nM) and carbachol (0.1-100 microM) dose dependently increased the amount of immunodetectable RhoA with a peak increase occurring at 3 min. High-affinity CCK-A-receptor agonists JMV-180 and CCK-OPE (1-1,000 nM) did not increase the intensities of the RhoA band, suggesting that stimulation of RhoA is mediated by the low-affinity CCK-A receptor. Although an increase in RhoA did not require the presence of extracellular Ca2+, the intracellular Ca2+ chelator 1, 2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid-AM abolished the appearance of the RhoA band in response to CCK and carbachol. The Gq protein inhibitor G protein antagonist-2A (10 microM) and the phospholipase C (PLC) inhibitor U-73122 (10 microM) markedly reduced RhoA bands in response to CCK. The protein kinase C (PKC) activator phorbol ester (10-1,000 nM) dose dependently increased the intensities of the RhoA band, which were inhibited by the PKC inhibitor K-252a (1 microM). The pp60(c-src) inhibitor herbimycin A (6 microM) inhibited the RhoA band in response to CCK, whereas the calmodulin inhibitor W-7 (100 microM) and the phosphoinositide 3-kinase inhibitor wortmannin (6 microM) had no effect. RhoA was immunoprecipitated with Src, suggesting association of RhoA with Src. Increases in mass of this complex were observed with CCK stimulation. In permeabilized acini, the Rho inhibitor Clostridium botulinum C3 exoenzyme dose dependently inhibited amylase secretion evoked by a Ca2+ concentration with an IC50 of C3 exoenzyme at 1 ng/ml. We concluded that the small GTP-binding protein RhoA p21 exists in pancreatic acini and appears to be involved in the mediation of pancreatic enzyme secretion evoked by CCK and carbachol. RhoA pathways are involved in the activation of PKC and Src cascades via Gq protein and PLC.

ADP Ribose Transferases↗

Developmental potential of mouse primordial germ cells.

There are distinctive and characteristic genomic modifications in primordial germ cells that distinguish the germ cell lineage from somatic cells. These modifications include, genome-wide demethylation, erasure of allele-specific methylation associated with imprinted genes, and the re-activation of the X chromosome. The allele-specific differential methylation is involved in regulating the monoallelic expression, and thus the gene dosage, of imprinted genes, which underlies functional differences between parental genomes. However, when the imprints are erased in the germ line, the parental genomes acquire an equivalent epigenetic and functional state. Therefore, one of the reasons why primordial germ cells are unique is because this is the only time in mammals when the distinction between parental genomes ceases to exist. To test how the potentially imprint-free primordial germ cell nuclei affect embryonic development, we transplanted them into enucleated oocytes. Here we show that the reconstituted oocyte developed to day 9.5 of gestation, consistently as a small embryo and a characteristic abnormal placenta. The embryo proper also did not progress much further even when the inner cell mass was 'rescued' from the abnormal placenta by transfer into a tetraploid host blastocyst. We found that development of the experimental conceptus was affected, at least in part, by a lack of gametic imprints, as judged by DNA methylation and expression analysis of several imprinted genes. The evidence suggests that gametic imprints are essential for normal development, and that they can neither be initiated nor erased in mature oocytes; these properties are unique to the developing germ line.

Animals↗

[Congestive heart failure due to a combination of atrial fibrillation and tricuspid regurgitation: clinical course and echocardiographical analysis].

The combination of atrial fibrillation (Af) and tricuspid regurgitation (TR) may induce the congestive heart failure (HF) due to insufficient output. However, these associations have not been elucidated. We examined the clinical course with echocardiographic data in 119 patients with Af and/or TR and/or HF. Their mean age was 65 +/- 14 years. The patients were classified into 6 groups as follows: Group I contained patients with Af, TR and HF(n = 13); Group II contained patients with Af and TR, without HF(n = 59); Group III contained patients with TR and HF, without Af(n = 15); Group IV contained patients with TR and without AF and HF(n = 15); Group V contained patients with Af and HF, without TR(n = 24); Group VI contained patients with Af and without TR and HF(n = 13). The fractional shortening and ejection fraction in Group I and II were significantly (p < 0.05) decreased compared to Group IV. Moreover, the fractional shortening in Group V was significantly (p < 0.05) lower than in Group IV. Among 72 cases in Group I and II, 24 cases were followed by echocardiography for 2 to 5 years. Eight cases of HF exhibited a no HF state and 1 demonstrated had the HF state. All 9 cases (38%) showed a decreased heart rate and no alternation of TR. Four of the 24 patients (17%) had developed worsened TR and a lowered ejection fraction but none developed them became HF. Therefore, tachycardia may be an accelerative factor for HF due to the combination of Af and TR, not due to the grade of TR.

Aged↗

Comparative accuracy of automated computer analysis versus physicans in training in the interpretation of electrocardiograms.

We compared the interpretation of an electrocardiogram (ECG) made by computer with that made by physicians in training, as well as with the diagnosis made by cardiologists. ECGs were collected from 1058 Japanese adults (812 men and 246 women, mean age 49 +/- 19 years). With the computer program, the incidence of false-negative reports was 10.5% while that of false-positive reports was 16.5%, when compared with the physician's diagnosis. The incidence of a false-positive diagnosis with the computer was 18 times higher than that found by the physicians in training. The results show the advantages and the limitations in the use of computers for analysis of ECGs.

Adult↗

Eight calves cloned from somatic cells of a single adult.

Eight calves were derived from differentiated cells of a single adult cow, five from cumulus cells and three from oviductal cells out of 10 embryos transferred to surrogate cows (80 percent success). All calves were visibly normal, but four died at or soon after birth from environmental causes, and postmortem analysis revealed no abnormality. These results show that bovine cumulus and oviductal epithelial cells of the adult have the genetic content to direct the development of newborn calves.

Animal Husbandry↗