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H Nishida

Publications and source records attributed to H Nishida.

At least 145 records · Page 8Linked to original sources
PubMed1998

Centrosome-attracting body: a novel structure closely related to unequal cleavages in the ascidian embryo.

The mechanism of unequal cleavage is one of the most intriguing subjects in cell biology. Previous studies of unequal cleavage have focused on a limited number of organisms such as yeasts, nematodes, sea urchins and annelids. The cleavage pattern of the ascidian embryo is invariant. In the ascidian embryo, the posterior-most blastomeres divide unequally in three successive cleavages. In the present study, it was shown that the ascidian embryo provides another good experimental system with which to analyze the mechanism of unequal cleavage. A novel structure, designated as CAB (centrosome-attracting body), which was found specifically in the unequally cleaving blastomeres was described. In the course of unequal cleavages, first, a thick microtubule bundle appeared between CAB and one of the centrosomes. Then with the shortening of the microtubule bundle, the nucleus with the centrosome was drawn toward CAB, situated at the posterior cortex of the blastomere. Finally, a cleavage furrow formed in the middle of the asymmetrically located mitotic apparatus and produced two blastomeres of different size, generating a smaller cell that inherits CAB. The CAB seemed to play an essential role in the unequal cleavages in the ascidian embryo.

Animals↗
PubMed1998

Mechanical circulatory support for severe heart failure after operation.

To evaluate the clinical results of circulatory support for severe heart failure after operation, we examined 62 patients (39 males and 23 females) who underwent circulatory support for postoperative heart failure from 1984 to 1996. Their ages ranged from 22 to 78 (mean 52) years. In 62 patients, 35 had valvular, 25 had ischemic, and 2 had congenital heart disease. Postoperation, 29 patients underwent venoarterial bypass (VAB), 20 had biventricular bypass (BVB), and 8 had left ventricular bypass (LVB). The remaining 5 patients received a pulsatile left ventricular assist device (LVAD). The weaning and discharge rates of the patients by type of support were 51.7% and 31.0% with VAB, 75.0% and 55.0% with BVB, 87.5% and 37.5% with LVB, and 60.0% and 40.0% with LVAD, respectively. The complete results of this series (64.5% weaning rate and 40.3% discharge rate) were acceptable.

Adult↗
PubMed1998

Afterload-dependent flow fluctuation of centrifugal pump: should it be actively fixed?

To evaluate the clinical meaning and effects of afterload-dependent flow fluctuation in a centrifugal pump, concomitant measurement of flow rate and mixed venous oxygen saturation (SVO2) was performed in 5 cases of open heart surgery in which the patients underwent cardiopulmonary bypass (CPB) with the Terumo Capiox centrifugal pump. Continuous measurement of SVO2 using the 3M CDI System 100 was performed with a disposable cuvette incorporated into the drainage circuit. After the target flow rate of 2.4 L/min/m2 was obtained under a nonbeating condition, the pump rotational speed was fixed. During the cooling and low temperature period, SVO2 decreased as the flow rate spontaneously decreased but still stayed around 80% even with a 15-20% decrease in blood flow rate. This indicates that a luxury perfusion condition is ensured as long as the body temperature is kept low. In contrast, during the rewarming period, SVO2 decreased to around 70-75% despite a 15-25% spontaneous increase in flow rate. Although this level of SVO2 still indicates adequate systemic perfusion, there is a possibility of regional hypoperfusion in patients with such conditions as cerebrovascular disease. In conclusion, although diligent adjustment of the physiological fluctuating flow rate in the centrifugal pump seems unnecessary during conventional open heart surgery, manual control may be necessary especially during the rewarming period, normothermic surgery, or circulatory assist for shocked patients. From this study, we also conclude that the major benefit of the afterload-independent autoflow control system of the centrifugal pump is the improvement of safety in terms of the fixed reservoir level and the handling of cardiopulmonary bypass.

Blood Flow Velocity↗
PubMed1998

Inhibition of 15-hydroxyprostaglandin dehydrogenase activity in rabbit gastric antral mucosa by panaxynol isolated from oriental medicines.

Panaxynol is a polyacetylene compound with anti-inflammatory and anti-platelet-aggregatory effects isolated from commonly used oriental medicines. The effects of panaxynol on the activity of prostaglandin-synthesizing and catabolizing enzymes in the rabbit gastric antral mucosa have been examined. At concentrations ranging from 25 to 200 microM panaxynol had no effect on the synthesis of prostaglandins E2, F2alpha and D2 from exogenous arachidonic acid in the microsomal fraction of the gastric mucosa whereas at 25-200 microM it dose-dependently inhibited the activity of 15-hydroxyprostaglandin dehydrogenase (PGDH), which catalyses the initial step of prostaglandin catabolism, in the cytosolic fraction. The concentration required for 50% inhibition (IC50) was approximately 25 microM. Inhibition of PGDH by panaxynol was non-competitive with regard to NAD+ and prostaglandin E2. These results suggest that panaxynol has the potential to inhibit PGDH activity in gastric mucosa, possibly as a result of pharmacological activity.

Alkynes↗
PubMed1998

Localization of parathyroid glands in hemodialysis patients using Tc-99m sestamibi imaging.

UNLABELLED: Tc-99m sestamibi parathyroid imaging was performed in 28 patients with chronic renal failure to localize abnormal parathyroid glands in patients receiving hemodialysis, and compared the localization with ultrasonography and magnetic resonance (MR) imaging. METHODS: We imaged 28 patients with secondary hyperparathyroidism using Tc-99m sestamibi (about 600 MBq) at 10 min and 2-3 h following radiotracer injection. In addition, mediastinal images were recorded at approximately 1 h following injection to identify ectopic parathyroid glands. All patients also were evaluated with ultrasonography and MR imaging. RESULTS: Tc-99m sestamibi scans demonstrated focal uptake in 60 glands of the 28 patients, and was categorized as slight uptake in 71.7% (43/60), and intense uptake in 28.3% (17/60). Seventeen of the 28 patients underwent parathyroidectomy. A total of 64 glands were resected. Sestamibi imaging was more sensitive for localizing abnormal parathyroid glands than ultrasonography or MR imaging. Histologic evaluation of 27 resected parathyroid glands revealed that the number of oxyphil or chief cells was not proportional to sestamibi uptake. CONCLUSION: Our data indicate that Tc-99m sestamibi imaging should be used initially to localize abnormal parathyroid glands in hemodialysis patients with secondary hyperparathyroidism, prior to MR imaging or ultrasonography. Sestamibi uptake in parathyroid glands may not correlate with the degree of hypercellularity of oxyphil cells.

Adult↗
PubMed1998

Developmental roles of nuclear complex factors released during oocyte maturation in the ascidians Halocynthia roretzi and Boltenia villosa.

The developmental roles of factors associated with the nuclear complex of Halocynthia roretzi and Boltenia villosa oocytes were investigated by cutting mature oocytes into animal and vegetal merogons before and during GVBD. Animal and vegetal merogons were cultured in sea water until the GV cytoplasm had dispersed within the cytoplasm of control oocytes and then they were cross-fertilized and scored for their ability to undergo normal development. Halocynthia oocyte fragments produced from the animal region of oocytes containing intact GVs exhibited a low frequency of polyspermy, a high frequency of fertilization and cleavage, and a high frequency of expressing an epidermal antigen, Epi-2. In contrast, merogons produced from the vegetal region of Halocynthia oocytes in which GVs were intact exhibited a high frequency of polyspermy, did not undergo cell division, and expressed a high frequency of Epi-2 expression. When vegetal fragments were produced after the dispersal of approximately 50-70% of the GV nucleoplasm, these merogons exhibited a low frequency of polyspermy, high frequencies of cell division (including the formation of epidermal layer), and in most cases expressed Epi-2. Vegetal Boltenia fragments produced during GVBD in some cases developed into larvae. These results suggest that the ascidian GV nucleoplasm may contain factors required for fertilization and cell division and that epidermal determinants reside in the oocyte cytoplasm.

Animals↗
PubMed1998

Recanalization after coil embolotherapy of pulmonary arteriovenous malformations: study of long-term outcome and mechanism for recanalization.

OBJECTIVE: We investigated the efficacy of steel coils for embolotherapy of pulmonary arteriovenous malformations (PAVMs) by reimaging the embolized PAVMs. CONCLUSION: We found a high incidence (57%; 8/14) of recanalization in PAVMs embolized with steel coils. Contrast-enhanced CT is useful for detection of recanalized PAVMs. Half of the recanalized PAVMs were fed by bronchial artery branches. Thus, coil embolization should be performed as close as possible to the PAVM to avoid future development of bronchial artery-to-pulmonary artery anastomoses that may cause recanalization.

Adolescent↗
PubMed1998

Comparison of technetium-99m-MIBI, technetium-99m-tetrofosmin, ultrasound and MRI for localization of abnormal parathyroid glands.

UNLABELLED: Abnormal parathyroid tissue can be identified by radionuclide imaging with either 99mTc-MIBI or 99mTc-tetrofosmin. This study compared the relative sensitivity of these two agents to localize parathyroid hyperplasia and adenoma. METHODS: Twenty patients with primary (n = 9) or secondary (n = 11) hyperparathyroidism were studied with 99mTc-MIBI and 99mTc-tetrofosmin parathyroid imaging, ultrasonography and MRI. Radionuclide images of the neck were acquired 10 min and 2-3 hr after radiopharmaceutical injection. The images were visually evaluated for abnormal focal areas of increased tracer localization in the neck and mediastinum. A parathyroid gland/normal thyroid tissue activity ratio (referred to as the P/T uptake ratio) was calculated for each positive scan. RESULTS: Of the 46 parathyroid glands surgically explored, the overall sensitivity and specificity of MIBI imaging were 83% and 83% (38/46); tetrofosmin imaging 87% and 83% (40/46); ultrasonography 78% and 40% (36/46); and MRI 80% and 60% (37/46), respectively. Both radiopharmaceuticals performed well in the nine patients found to have adenoma. The sensitivity and specificity of MIBI imaging were 100% and 100% (9/9); tetrofosmin imaging 100% and 100% (9/9); ultrasonography 78% and 67% (7/9); and MRI 100% and 100% (9/9), respectively. In the 37 glands with hyperplasia, MIBI imaging had a sensitivity of 78% and specificity of 75%; tetrofosmin imaging 84% and 75%; ultrasonography 78% and 43%; and MRI 73% and 60%, respectively. CONCLUSION: All imaging techniques localized abnormal parathyroid glands. The radiotracers have equal sensitivity for the localization of abnormal parathyroid glands. The sensitivity of these tracers was high as compared to ultrasonography or MRI.

Adenoma↗
PubMed1998

[The effect of MS-551 on two VT/Vf patients in CABG: a case report].

Uncontrollable arrhythmia is one of the causes of operative death in CABG. We report two cases of successful treatment of recurrent VT/Vf in CABG operation by MS-551. One case was a 72-year-old male, who had unstable angina and OMI with left ventricular dysfunction (LVEF 24%). After weaning from CPB, the rhythm turned into VT/Vf suddenly. Lidocaine and verapamil were not effective. VT/Vf recurred over the over. The another case was a 52-year-old male, who had OMI and effort angina. He became myocardial infarction during operation. VT/Vf occurred after the weaning from CPB. Lidocaine and amiodarone were of no effect on his VT/Vf. In both cases, intravenous injection of MS-551 promptly stopped VT/Vf. Use of MS-551 was limited mainly on DCM patients. But other antiarrhythmic agents were ineffective on these cases. We have had to continue support circulation for a long time without MS-551. As MS-551 is being used as a trial on medically followed patients, it was unknown how effective clinically on the acute myocardial infarction. In this regard, our cases may suggest a positive answer to that.

Aged↗
PubMed1998

[Evaluation of blood flows inside hepatic tumors using color Doppler echography with galactose-based intravenous contrast medium "SH/TA 508" administration].

The purpose of this study is to evaluate hemodynamic characteristics of various hepatic tumors using color Doppler echography administered galactose-based intravenous contrast medium "SH/TA 508 (Levovist)". Subject were 9 cases of hepatocellular carcinomas, 5 cases of metastatic liver tumors and a case of hemangioma. We evaluated the characteristics of blood flows inside various hepatic tumors, and also evaluated the first pass through the hepatic tumors during administration of Levovist. The strongly pulsatile branched blood flows inside tumor and the slow-increased and plateau patterns were observed in the all cases of hepatocellular carcinomas, the weakly pulsatile blood flows surrounding tumor and the rapid-increased and slow-decreased patterns were observed in the cases of metastatic liver tumors, and the continuous blood streams in the margin of tumor and the slow-increased and slow-decreased pattern were observed in the case of hemangioma. These findings were characteristic in various hepatic tumors, and color Doppler echography enhanced by Levovist was very useful to distinguish hepatic tumors.

Carcinoma, Hepatocellular↗
PubMed1998

[A surgical case of angina pectoris with a severe stenosis of Lt. mid-cerebral artery: the usefulness of the monitoring of cerebral blood flow].

A 64-year-old male patient had two episodes of transient ischemic attack and a cerebral infarction. Cerebral angiography showed 50% stenosis at the junction of left internal carotid artery and 90% stenosis at left mid-cerebral artery (MCA). Coronary angiography showed two vessel disease with arteriosclerotic change and underwent coronary artery bypass grafting. To prevent intraoperative cerebral infarction, we used brain protect solution just before starting ECC, set perfusion flow around 3 l/min/m2, monitored the flow of left MCA using Transcranial Doppler (TCD) and the saturation of left internal jugular vein (SjO2) continuously. PaCO2 was controlled around 45 mmHg. TCD showed good pulsatile flow, and SjO2 was kept over 60%. The patient recovered consciousness 2 hours after operation in the intensive care unit without paresthesia. We thought the number of open-heart cases with cerebrovascular disease increased, and pulsatile low of ECC by intraaortic balloon pumping and the monitoring of SjO2 are useful for the cases.

Angina Pectoris↗
PubMed1997

Developmental fates of larval tissues after metamorphosis in ascidian Halocynthia roretzi. I. Origin of mesodermal tissues of the juvenile.

Cell lineages during ascidian embryogenesis are invariant. In a previous study, the developmental fate of each blastomere during embryogenesis of the ascidian Halocynthia roretzi was analyzed in detail by intracellular injection of a tracer molecule, horseradish peroxidase (Nishida, H., Dev. Biol. 121, 526-541, 1987). In the present study, the developmental fates of various larval mesodermal tissues after metamorphosis in H. roretzi were traced by labeling each precursor blastomere of larval tissues. Mesenchyme cells of larvae gave rise to tonic cells of juveniles. Trunk ventral cells gave rise to body-wall (atrial siphon and latitudinal mantle) muscle, heart, and pericardium of juvenile. Trunk lateral cells gave rise to blood (coelomic) cells as well as body-wall (oral siphon and longitudinal mantle) muscle. Larval muscle and notochord cells did not contribute to juvenile tissues. It was revealed that it is predictable to which juvenile tissue a blastomere of the 110-cell embryo will give rise. Therefore, in ascidian development, developmental fates after metamorphosis were almost invariant with regard to cell type of descendants.

Animals↗
PubMed1997

Peroxynitrite induces the conversion of xanthine dehydrogenase to oxidase in rabbit liver.

Effect of peroxynitrite (ONOO-) on the conversion of xanthine dehydrogenase to oxidase in rabbit liver was examined. ONOO- (25-200 microM) induced the conversion of xanthine dehydrogenase to oxidase in a dose-dependent manner. The addition of hydroxyl radical scavengers (mannitol and dimethyl sulfoxide) gave no alteration in the ONOO(-)-induced conversion of xanthine dehydrogenase to oxidase, implying that the action of ONOO- is not due to hydroxyl radicals which may be formed from ONOO-. The experiment utilizing dithiothreitol also revealed that the action of ONOO- might be due to oxidation of sulfhydryl group of xanthine dehydrogenase. These results suggest that ONOO- has the potential to convert xanthine dehydrogenase to oxidase, and that this effect may be correlated with cytotoxic actions of ONOO-.

Animals↗
PubMed1997

Induction of trunk lateral cells, the blood cell precursors, during ascidian embryogenesis.

The tadpole larvae of the ascidian Halocynthia roretzi have trunk lateral cells (TLCs) in their trunk. TLCs give rise to adult blood cells after metamorphosis. TLCs are exclusively derived from the A7.6 cell pair of 64-cell embryos. When prospective TLC blastomeres were isolated from embryos before the 16-cell stage, they failed to express TLC-specific antigen, a molecular indication of differentiation of TLCs. Isolates after the 32-cell stage, however, autonomously expressed the antigen. Results of experiments involving coisolation and recombination of blastomeres at the 16-cell stage showed that the inductive influence emanating from cells of animal hemisphere (presumptive epidermis blastomeres) is required for TLC formation. The inductive interaction takes place at the 16-cell stage, two cell cycles before the developmental fate becomes exclusively restricted to TLC formation. The inducing activity is distributed widely in animal hemisphere. By contrast, only presumptive TLC blastomeres have competence to be induced to form TLCs.

Animals↗
PubMed1997

Cell lineage and timing of fate restriction, determination and gene expression in ascidian embryos.

Tadpole larvae of ascidians show the basic body plan of chordates. An ascidian larva consists of only few types of cells and has a relatively small number of cells. Cell lineages are simple and invariant among individuals and have been described in detail. The clonal restriction of developmental fate takes place considerably early in development. I review here the temporal relationship between fate restriction, determination and initiation of lineage-specific gene expression during ascidian embryogenesis. In several cases, determination and initiation of gene expression precede fate restriction and occur during the last cell cycle before fate restriction. Such a phenomenon contradicts the traditional view of fate specification and has several important implications for the understanding of the way in which cells execute the developmental pathway.

Journal Article↗
PubMed1997

Localization of ectopic parathyroid glands using technetium-99m sestamibi imaging: comparison with magnetic resonance and computed tomographic imaging.

The aim of the study was to compare the accuracy of technetium-99m sestamibi imaging for localization of ectopic parathyroid glands in patients with hyperparathyroidism with that of magnetic resonance (MR) and computed tomographic (CT) imaging. Eleven patients with primary (n=3) or secondary (n=8) hyperparathyroidism were studied with 99mTc sestamibi parathyroid imaging CT and MR imaging. Images of the neck were acquired at 10 min and 2-3 after tracer injection. The three patients with primary hyperparathyroidism and five patients with secondary hyperparathyroidism underwent parathyroidectomy. The ectopic glands were confirmed by histopathological examination of the resected specimens. In respect of 20 parathyroid glands in the eight patients explored surgically, the sensitivity and specificity of sestamibi imaging were 70% (14/20) and 88%, respectively, those of CT, 40% (8/20) and 88%, and those of MR imaging, 60% (12/20) and 88%. Of these patients, three had parathyroid adenomas while five had hyperplasia (17 glands). Sestamibi imaging localized eight ectopic parathyroid glands, which were surgically confirmed (six were located in the thymus and two in the mediastinum). In one patient explored surgically, the ectopic gland was located outside the field of the MR coil. Although the remaining three cases of secondary hyperparathyroidism were not confirmed surgically, these patients demonstrated sestamibi uptake in five parathyroid glands, including three ectopic glands. MR images demonstrated abnormal parathyroid glands in the same regions as sestamibi imaging. Our data indicate that 99mTc-sestamibi imaging should be used initially to localize the ectopic parathyroid glands in patients with hyperparathyroidism for anatomical guidance prior to MR or CT imaging.

Choristoma↗