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Y Tsunoda

Publications and source records attributed to Y Tsunoda.

At least 145 records · Page 8Linked to original sources
PubMed1989

[Investigation of Limulus test during and after cardiopulmonary bypass--analysis of Limulus positive substance and particles in the cardiopulmonary bypass circuit].

Patients undergoing heart surgery with cardiopulmonary bypass (CPB) frequently have positive Limulus test without any remarkable signs of endotoxemia. CPB circuit could be one of the possible causes of this phenomenon, but the exact mechanism has not been studied. Accordingly, a prospective study was made in 41 patients undergoing heart surgery with CPB. Limulus test were performed on the samples of priming fluids of CPB including the plasma and urine of those patients during and after surgery. Besides the Limulus test, the CPB fluids were analysed by the false positive test. Microscopic examinations were carried out on the priming fluids before and after using a 40 microns filter during recirculation without washing the CPB circuit and the fluid from a 4 microns filter been washed by 2000 ml of Martose-10 in order to find out the presence of any foreign particles in the CPB circuit. The size and the number of particles were measured by coulter counter. The studies revealed the following facts, 1) Limulus test; most of the samples from priming fluids (31/35), plasma circulating the CPB (36/36), urine during CPB (22/25) and plasma (34/35) and urine (21/30) just after the surgery revealed positive. However, only 4 samples from plasma at 3POD and 2 samples from urine at 2POD revealed positive, 2) false positive test of the samples from priming fluids was negative meaning the Limulus positive substances are not endotoxin, 3) under microscopic analysis and coulter counter, there were about 40 particles over 50 microns per ml of priming fluids before washing the CPB circuit.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1988

Spatial distribution and temporal change of cytoplasmic free calcium in human platelets.

Our digital imaging microscope equipped with a microspectrofluorometer revealed in single resting human platelets the existence of continuous Ca2+ gradient increasing towards the plasma membrane (frequency; 100%) and discontinuous ones (Ca2+ plateaus) in the endoplasmic regions (frequency: 70%). An average cytoplasmic free Ca2+ concentration ([ Ca2+]i) in a whole cytoplasm was 72 +/- 7 nM, ranging from 30 nM in the lowest to 150 nM in the highest region just beneath the plasma membrane. When stimulated with thrombin, [Ca2+]i uniformly increased to the average [Ca2+]i of 300 nM and these gradients disappeared. This [Ca2+]i transient was followed by the sustained increase in [Ca2+]i in both single cells and cell suspension.

Blood Platelets↗
PubMed1988

A role for Ca2+ in mediating hormone-induced biphasic pepsinogen secretion from the chief cell determined by luminescent and fluorescent probes and X-ray microprobe.

In isolated chief cells from the guinea pig, cholecystokinin (10 nM) and a high concentration of ionomycin each caused a biphasic pattern of pepsinogen secretion. The initial fast response to cholecystokinin was not dependent on medium Ca2+ ans was mimicked by low concentration of ionomycin (100 nM). Inositol 1,4,5-trisphosphate caused a similar fast release from permeabilized cells. The slow component of release was dependent on medium Ca2+, however, and was mimicked by the phorbol ester 12-O-tetradecanoylphorbol 13-acetate (TPA) (100 nM) or the diacylglycerol analogue 1-oleoyl-2-acetylglycerol (OAG) (100 microM). Ionomycin (100 nM) and TPA (and/or OAG), when applied together, reproduced the biphasic pattern of pepsinogen secretion, suggesting that the signalling pathways utilized by both types of agonist contribute to the response evoked by cholecystokinin-hormone stimulation. Both fura-2 and aequorin were used to monitor changes of intracellular Ca2+. Three pathways were found to contribute to the Ca2+ transient. A rapid release of Ca2+ from intracellular store(s), a rapid Ca2+ entry from the extracellular space, and a more sustained Ca2+ entry from the extracellular space. Cholecystokinin induced a rapid increase in cytoplasmic Ca2+ ([Ca2+]i) as estimated with fura-2 and aequorin. This rise was reduced but not abolished upon removal of extracellular Ca2+, suggesting that both Ca2+ entry from the extracellular space and Ca2+ mobilization from the intracellular store(s) contribute to the initial, fast component of the Ca2+ transient. A second, more sustained component of the Ca2+ transient induced by cholecystokinin was abolished by lanthanum. TPA and OAG induced a biphasic Ca2+ transient that could be detected only with aequorin. The late, sustained component of this response was again abolished by lanthanum as well as by removal of extracellular Ca2+. It appears that the late component of the Ca2+ transient is dependent on Ca2+ influx from the extracellular space and is too localized to be detected by fura-2. Prestimulation of cells with TPA or OAG prevented the aequorin transient caused by cholecystokinin and vice versa, suggesting that TPA, OAG and cholecystokinin activate the same pathways of Ca2+ entry into the cytosol from the intracellular store(s) or the extracellular space. The stimulation-sensitive Ca2+ pool was examined with electron probe X-ray microanalysis. It appears to be restricted to an area enriched in secretory granules or peripheral endoplasmic reticulum just beneath the apical plasma membrane and in close association with the microtubular-microfilamentous system.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1988

Initial and sustained calcium mobilizations in the parietal cell during stimulations with gastrin, inositol trisphosphate, phorbol ester and exogenous diacylglycerol.

Electron probe X-ray microanalysis revealed that cytoplasmic Ca2+ concentration increased in the restricted apical cytoplasm during stimulation of isolated guinea pig parietal cells with gastrin. Furthermore, this study, using 45Ca2+, aequorin and fura-2, revealed the mechanism involved in intracellular Ca2+ shifts caused by gastrin and the involvements of inositol 1,4,5-trisphosphate (IP3) and diacylglycerol in producing those shifts. The gastrin-mediated and IP3-sensitive Ca2+ pool was located in the smooth-surfaced membrane-enriched areas and released Ca2+ in the initial phase. Gastrin-mediated Ca2+ mobilization was also evoked by diacylglycerol, comprising an intracellular Ca2+ mobilization followed by a late, sustained and more localised Ca2+ entry from the extracellular space.

Adenosine Triphosphate↗
PubMed1988

Fluorescence digital image analysis of the inositol trisphosphate-mediated calcium transient in single permeabilized parietal cells.

The myo-inositol 1,4,5-trisphosphate (IP3)-induced Ca2+ mobilization in single saponin-permeabilized and fura-2-loaded parietal cells was analysed by a fluorescence digital image processor. When the cells were incubated with ATP, free cytoplasmic Ca2+ concentration [( Ca2+]i) increased in some restricted cytoplasmic regions showing discontinuous plateau and in the peripheral cytoplasm showing continuous [Ca2+]i gradient towards the plasma membranes. When treated with IP3, the high plateau enlarged to the entire cytoplasm and (a) new higher plateau(s) appeared and enlarged again in a transient manner. The IP3-induced Ca2+ transient was also observed by fluorescence microphotometry of the single cells or by fluorescence spectrophotometry and 45Ca2+ uptake experiment of the cell population.

Animals↗
PubMed1988

Effects of induction current and other factors on large-scale electrofusion for pronuclear transplantation of mouse eggs.

In this paper, we describe the procedure of large-scale and efficient electrofusion for pronuclear transplantation in mouse eggs and the tolerance of the eggs for electric stimulus, assessed in vitro and in vivo development. The fusion chamber was arranged in parallel by dielectrodes (30-mm length, 1-mm width, and 2-mm height), and 0.3 M mannitol in distilled water was used as a fusion solution. The agglutination cleavage of enucleated eggs with karyoplast was easily orientated in parallel with electrodes by alternating current between 100 and 500 kHz at 2 and 10 V/mm. Immediately after the orientation, a direct current of 150 V/mm was given for 200 microseconds twice and repeated three times to induce fusion of the enucleated eggs with karyoplast. More than five eggs, at least, can be submitted to electrofusion at the same time. The eggs that were not fused were treated again in the same manner. The proportion of eggs fused with karyoplast was increased by preincubation in M16 medium prior to submitting them to the electrofusion. When the eggs were incubated for 60 min, 80% of them were fused with karyoplast by the first electric treatment; in contrast, only 19% of the eggs were fused if they were submitted to electrofusion directly. It was found that between the CD-1 and F1 strains there was a difference in tolerance of the eggs to electric stimulus and that this was depend on the nuclei but not on cytoplasm.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Development of enucleated parthenogenones that received pronuclei or nuclei from fertilized mouse eggs.

This study compares the developmental potential of enucleated mouse parthenogenones that received pronuclei from fertilized eggs with those that received nuclei from late two-cell embryos. The proportion of reconstituted parthenogenones, which received pronuclei at the one-cell stage, that developed to blastocysts in vitro and to live fetuses after transfer to recipients was significantly lower than that of reconstituted control eggs. However, the in vitro and in vivo developmental potential of reconstituted parthenogenones that received nuclei at the two-cell stage from fertilized late two-cell embryos was not different from that of reconstituted control eggs. These results were contrary to those reported previously by Mann and Lovell-Badge (1984), who showed that parthenogenetic eggs receiving pronuclei from fertilized eggs developed well both in vitro and in vivo.

Animals↗
PubMed1988

Cryopreservation of rat blastocysts by vitrification.

Rat blastocysts equilibrated with vitrification solution (VS1), consisting of dimethyl sulfoxide, acetamide, propylene glycol, and polyethylene glycol were plunged directly into liquid nitrogen. The embryo suspension are solidified by an extreme elevation in viscosity of solution. The embryos are cryopreserved by vitrification without intra- and extracellular ice formation. The proportion of morphologically normal embryos after cooling and warming was 79% (117/149) and all (48/48) of the embryos cultured were developed to expanded or hatched blastocysts. Normal live young were obtained 41% of the time (28/69) after transfer of the cooled and warmed embryos to pseudopregnant recipients.

Animals↗
PubMed1988

Ovicidal effects of vitrification solution and the vitrification-warming cycle and establishment of the proportion of toxic effects on nuclei and cytoplasm of mouse zygotes.

The present study was conducted to compare the resistance of the nuclei with that of the cytoplasm of mouse zygotes to damage during the vitrification-warming cycle using the technique of pronuclear transplantation. Zygotes were collected from the oviduct of superovulated F1 female mice mated with males of the same strain. They were cryopreserved by the vitrification method. After being diluted with glycerol-sucrose PB1 solution, 86% of the recovered zygotes were morphologically normal and 80% of them developed to the two-cell stage in vitro, but the proportion of zygotes which developed to blastocysts was only 27%. When zygotes were exposed to VS1 solution in the same manner as above without cooling, 61% of them developed to blastocysts. In order to examine the source of injury during vitrification, the pronuclei of vitrified zygotes were transferred into enucleated fresh zygotes and vice versa. The developmental rate of blastocysts from vitrified zygotes that were enucleated and fused with pronuclei from fresh zygotes was significantly higher than that of zygotes reconstituted reversely. These findings suggest that nuclei are apparently damaged more than cytoplasm by the vitrification-warming cycle and the toxicity of VS1 solution.

Animals↗
PubMed1988

Intracellular Ca2+ shift and signal transduction from the tubulovesicular portion of gastric parietal cells during gastrin stimulation or Ca2+ ionophore treatment: comparison between luminescent and fluorescent probes, and electron probe X-ray microanalyzer.

In gastrin-stimulated, aequorin-loaded parietal cells from guinea pig gastric mucosa, a rapid but transient increase in the cytosolic free Ca2+ concentration ([Ca2+]i), owing to Ca2+ released from the store(s), and a more prolonged Ca2+ entry from outside the cells were observed. However, there was a little increase in [Ca2+]i when similar measurements were assessed by quin 2 or fura-2 in physiological saline. However, depletion or elimination of Na+ from the incubation medium caused a significant increase in the [Ca2+]; response to gastrin as measured by quin 2. These findings suggest that aequorin and quin 2 (or fura-2) provide information about different aspects of Ca2+ homeostasis and that there is an inhomogeneity of [Ca2+]i in the cytoplasm during gastrin stimulation. By the gastrin stimulation, the intracellular Ca2+ gradients were shifted from the unidentified portion(s) to the restricted apical cytoplasm, as determined by electron probe X-ray microanalysis. Therefore, localization and identification of the source of intracellular Ca2+ as a pool were determined by an X-ray microanalyzer. In the resting state, the tubulovesicle had high Ca2+ concentration compared with the level in the apical cytoplasm. Cells treated with the Ca2+ ionophore ionomycin had a decreased tubulovesicular Ca2+ level, followed by a reciprocal increase in area of the canalicular membrane. The secretory canaliculus in stimulated cells had lower Ca2+ or higher K+ and Cl- concentrations than that of tubulovesicles or cytoplasm in the resting state, respectively. These findings suggest that the Ca2+ pool of the parietal cell is in the tubulovesicles and (or) luminal cell membrane and that the Ca2+ released from the store(s) may mediate a flow of K+ or Cl- into the secretory canaliculus.

Aequorin↗
PubMed1988

Visualization of cytosolic free calcium distribution and mobilization in guinea pig gastric chief cells.

Distribution and temporal change of free calcium concentration [( Ca2+]i) in single guinea pig gastric chief cells were visualized by a digital imaging microscope equipped with a microspectrofluorometer. The distribution was not homogeneous; a higher [Ca2+]i area was often localized in some restricted regions of the endoplasm and also at the peripheral cytoplasm just beneath the plasma membrane. When stimulated with cholecystokinin, [Ca2+]i increased transiently in the apical peripheral cytoplasm and in the endoplasmic regions. This Ca2+ mobilization which precedes the biphasic pepsinogen secretion was composed of a rapid Ca2+ release from the intracellular store(s) as well as a rapid and a more sustained Ca2+ entry from the extracellular space.

Animals↗
PubMed1988

Differential sensitivity of mouse pronuclei and zygote cytoplasm to Hoechst staining and ultraviolet irradiation.

The exposure of mouse zygotes pre-stained with Hoechst 33342 to u.v. irradiation for 20-30 sec significantly or completely inhibited development to blastocysts in vitro. However, development to the blastocyst stage of enucleated eggs receiving pronuclei from untreated eggs was as good as that of control reconstituted eggs when the cytoplasm originated from eggs exposed to u.v. irradiation for 20-30 sec, but was significantly lower when the cytoplasm was from eggs exposed for 40 sec. The chromosomes at the second metaphase stage could be removed with 15 sec of exposure to u.v. irradiation under a fluorescence microscope. Most eggs enucleated at the second metaphase that received a single inner cell mass nucleus (75%) showed pronuclear formation 6 h after activation; 23% of them developed to morphologically normal 2-cell eggs and 5% developed to blastocysts. These results demonstrate that the cytoplasm of mouse zygotes is more resistant to u.v. irradiation after Hoechst staining. Eggs at the second metaphase, from which chromosomes have been removed under a fluorescence microscope, can therefore be used as cytoplasm recipients for nuclear transplantation of inner cell mass nuclei.

Animals↗
PubMed1987

Porcine ileal polypeptide causes an increase in cytoplasmic Ca2+ in both parietal and chief cells resulting in acid and pepsinogen secretion.

Porcine ileal polypeptide, an enterooxyntin isolated from distal small intestinal mucosal epithelium, has been observed to stimulate gastric acid secretion in vivo as well as in vitro (Wider, M.D. et al. (1984) Endocrinology 115, 1484-1491, Wider M.D. et al. (1986) Endocrinology 118, 1546-1550). We report here that porcine ileal polypeptide stimulates both acid (aminopyrine accumulation) and pepsinogen secretion in isolated, enriched populations of guinea pig parietal and chief cells in a dose-dependent manner. Further, 10(-9) M porcine ileal polypeptide caused an increase in cytoplasmic Ca2+ concentration in both parietal and chief cells similar in magnitude to that observed with gastrin-17 (10(-8) M) (as measured by both fura-2 and aequorin) and cholecystokinin octapeptide (CCK-OP) (10(-8) M), respectively. Porcine ileal polypeptide has been observed to cause no stimulation of cAMP production in gastric glands from guinea pigs (Gespach, C., personal communication) nor is there any effect of medium Ca2+ depletion on acid production observed with guinea pig gastric mucosal sections. It is concluded that porcine ileal polypeptide, at concentrations similar to circulating levels observed in plasma of normal pigs (5 x 10(-9) M), acts directly on the parietal and chief cells to cause the mobilization of intracellular Ca2+ from the stores resulting in acid and pepsinogen secretion. These experiments demonstrate that this peptide is a potent enterooxyntin and chief cell secretagogue which acts via the same signal transduction mechanisms as gastrin and cholecystokinin.

Aminopyrine↗
PubMed1987

Calcium-activated membrane depolarization via modulation of chloride efflux from parietal cells during gastrin stimulation.

In the isolated parietal cell the following observations were made: gastrin led to an increase in cytoplasmic free Ca2+ concentration ([Ca2+]i) even in the absence of medium Ca2+ and to transient membrane depolarization in both the absence of the medium Ca2+ and the fura-2-loaded cell. The incorporated Ca2+ chelator BAPTA inhibited the gastrin-induced membrane depolarization. The magnitude of depolarization caused by gastrin was unchanged on removal of medium Na+. Furosemide but not tetraethylammonium inhibited the gastrin-induced depolarization. The results suggest that the Ca2+ released from the store(s) induces membrane depolarization, possibly via modulation of a Cl- efflux across the luminal surface during gastrin stimulation.

Animals↗
PubMed1987

The cholecystokinin-induced Ca2+ shuttle from the inositol trisphosphate-sensitive and ATP-dependent pool, and initial pepsinogen release connected with cytoskeleton of the chief cell.

In guinea pig chief cells, inositol 1,4,5-trisphosphate (IP3) caused release of Ca2+, which was accumulated by ATP, from an endoplasmic reticulum-enriched fraction in both the permeable system and the cell-free system. This was mimicked with the Ca2+ ionophores A23187 and ionomycin on a large scale since an IP3-sensitive Ca2+ pool might be a subset of the Ca2+ ionophore-sensitive Ca2+ pool. The permeable chief cells, but not the cell-free system, retained the ability to react to synthetic cholecystokinin octapeptide (CCK-OP) with Ca2+ release from an IP3-sensitive pool due to of the non-additive but constant effect in exerting Ca2+ release from the store(s) induced by the combination with IP3 and CCK-OP. The increase in the cytosolic free Ca2+ concentration of intact chief cells responding to CCK-OP or the Ca2+ ionophore, ionomycin, comprised two components, namely, that by the Ca2+ entry from the extracellular space, and that by the Ca2+ release from the intracellular space(s) (as measured by fura-2). When CCK-OP or ionomycin was added, there was a biphasic response of pepsinogen secretion. An initial but transient response reaching a peak in 5 min was followed by a sustained response reaching a peak in 30 min. The initial pepsinogen release was independent of medium Ca2+, whereas the sustained one was dependent on medium Ca2+. The results suggest that the intracellular Ca2+ release from the store(s), presumably endoplasmic reticulum, may trigger the initial pepsinogen release, whereas the sustained pepsinogen secretion may be caused by acting in concert with the initial response and external Ca2+ entry. On the other hand, the disruption of the microtubular-microfilamentous system by colchicine or cytochalasin D failed to cause the Ca2+ release evoked by either IP3, CCK-OP or Ca2+ ionophores and to cause the CCK-OP- or ionomycin-induced initial pepsinogen release. These findings suggest that the IP3-sensitive pool is the same Ca2+ store which is completely or partially sensitive to CCK-OP and Ca2+ ionophores, respectively, and that the assembly of the cytoskeletal system is involved in initial intracellular Ca2+ metabolism and the following initial pepsinogen release. The assembly of the cytoskeletal system may be an early event in mediating the CCK-OP-induced initial pepsinogen release, perhaps by causing the Ca2+ release from an IP3-sensitive pool of the chief cell. The translocation or attachment of the IP3-sensitive pool brought about by cytoskeletal system might be necessary to cause Ca2+ release after the cell stimulation with CCK-OP.

Adenosine Triphosphate↗
PubMed1987

Full-term development of mouse blastomere nuclei transplanted into enucleated two-cell embryos.

The nuclei from four- and eight-cell mouse embryos were transplanted into enucleated two-cell embryos. It was found that such embryos not only developed to the blastocyst stage in vitro (72% and 35%), but also developed to full term (22% and 8%) after transfer to recipient mice. However, development of embryos which contained nuclei from the inner cell mass was not observed. Since the development of enucleated zygotes which contain advanced nuclei is limited (the present study; McGrath and Solter: Science, 226:1317-1319, '84; Robl, Gilligan, Critser, and First: Biol. Reprod., 34:733-739, '86), it appears that cytoplasmic factors are important for the development of nuclei from advanced cells.

Animals↗