Search PubMed⌕ Search

Biomedical subjects

H Nishida

Publications and source records attributed to H Nishida.

At least 163 records · Page 9Linked to original sources
PubMed1997

Cochlear microphonics recordable at the non-shielded bedside using a new tubal transducer.

A new tubal transducer (NC-3) for measuring cochlear microphonics (CM) in extratympanic electrocochleography (ECochG) was developed by improving the common hearing aid earphone. Using a human forearm as a dummy ear, the artifact contamination generated from the NC-3 tubal transducer was tested and the possibility of measuring the CM at a non-shielded bedside was studied. An HN-5 electrode was fixed to a subject's forearm, and a sound stimulus of 90 dBnHL was delivered through the tube of the NC-3. When the earphone of the transducer was placed at a right-angle to the electrode on either a vertical or horizontal plane and the electrode was placed in direct contact with the tip of the tube, contamination from electromagnetic induction and CM-like mechanical vibration were prevented. Using the HN-5 electrode and NC-3, extratympanic ECochG-CM was recorded from normal-hearing subjects in both a shielded soundproof room and a non-shielded ordinary, quiet room. No differences were found between CMs measured in the two rooms. These results suggest that the NC-3 overcomes the shortcomings of a loudspeaker system and allows CM to be recorded accurately at non-shielded bedsides.

Acoustic Stimulation↗
PubMed1997

Cell fate specification by localized cytoplasmic determinants and cell interactions in ascidian embryos.

Tadpole larvae of ascidians show the basic body plan of chordates. An ascidian larva consists of only a few types of cells and has a relatively small number of cells. Cell lineages are invariant among individuals and have been described in detail. These advantages facilitate the analysis of how the fate of each blastomere becomes specified during development. Over a century of research on ascidian embryogenesis has uncovered many interesting features concerning cellular mechanisms responsible for the fate specification. During embryogenesis, the developmental fate of a blastomere is specified by one of three different mechanisms: localized maternal cytoplasmic determinants, inductive interactions, or lateral inhibition in an equivalence cell group.

Animals↗
PubMed1997

Ras is an essential component for notochord formation during ascidian embryogenesis.

In ascidian embryos, inductive interactions are necessary for the fate specification of notochord cells. Previous studies have shown that notochord induction occurs at the 32-cell stage and that basic fibroblast growth factor (bFGF) has notochord-inducing activity in ascidian embryos. In vertebrate, it is known that bFGF receptors have tyrosine kinase domain and the signaling pathway is mediated by the small-GTP binding protein, Ras. To study the role of Ras in ascidian embryos, we injected dominant negative Ras (RasN17) into fertilized eggs. RasN17 inhibited the formation of notochord, suggesting that the Ras signaling pathway is involved in signal transduction in the induction of notochord cells. When the presumptive-notochord (A6.2) blastomere was co-isolated with the inducer (A6.1) blastomere and then RasN17 was injected into the A6.2 blastomere, notochord differentiation was suppressed. The presumptive-notochord blastomeres injected with RasN17 were treated with bFGF. Many of them failed to develop notochord-specific features. Next, we examined the effect of injecting constitutively active Ras (RasV12) into the A6.2 blastomeres. However, microinjection of RasV12 into these cells did not bypass notochord induction. These results suggest that the Ras signaling pathway is essential for the formation of notochord and that another signaling pathway also must be activated simultaneously in notochord formation during ascidian embryogenesis.

Animals↗
PubMed1997

Analysis of the temporal expression of endoderm-specific alkaline phosphatase during development of the ascidian Halocynthia roretzi.

During embryogenesis of ascidians, endoderm cells initiate certain processes associated with differentiation and produce a tissue-specific enzyme, alkaline phosphatase (ALP). ALP has been used as a histochemical marker of endoderm differentiation. In the present study, the temporal profile of ALP expression during embryogenesis was investigated. In Halocynthia roretzi, endoderm-specific ALP is a membrane bound protein and is distinguishable from maternal cytoplasmic ALP by molecular mass. The activity of endodermal ALP first appeared at the early tail-bud stage. Treatment of developing embryos with inhibitors of translation and transcription was started at various stages. The results suggested that the synthesis of endodermal ALP protein started at the early tail-bud stage, and that the transcription of mRNA was initiated in the gastrula. In other ascidians, Ciona and Styela, it has been suggested that a significant amount of maternal ALP mRNA exists in eggs. The present study revealed that there are significant species differences in ALP expression during ascidian embryogenesis.

Alkaline Phosphatase↗
PubMed1997

Clinical evaluation of pulsatile flow mode of Terumo Capiox centrifugal pump.

The Terumo Capiox centrifugal pump system possesses an automatic priming function in which the motor repeatedly stops and runs intermittently to eliminate air bubbles in the circuit through the micropores of the hollow-fiber membrane oxygenator. By modifying this mechanism, we have developed a pulsatile flow mode. In this mode, maximum and minimum pump rotational speeds can be independently set every 20 rpm in the range of 0 to 3,000 rpm. The duration of the pump run at maximum and minimum speeds can also be independently set every 0.1 s in the range of 0.2 to 15 s. In a clinical trial, after obtaining the desired flow rate, 2.4 L/min/m2 in nonpulsatile flow mode, a pulsatile flow mode of 60 cycles/min (with 1 cycle being maximum speed for 0.4 s and minimum speed for 0.6 s) was obtained by adding and subtracting 500 rpm to and from the rotational speed in nonpulsatile flow mode. Pulse pressures in the femoral artery and in the circuit just proximal to the perfusion cannula (6.5 mm Sarns high flow cannula with metal tip) were measured in 5 patients who underwent pulsatile cardiopulmonary bypass (CPB) for a coronary artery bypass graft (CABG), and compared to pulse pressures obtained by intraaortic balloon pumping (IABP) in 3 patients and by the pulsatile mode of the 3M Delphin pump in 3 patients. The platelet count, free hemoglobin, and beta-thromboglobulin (beta-TG) were measured and compared with measurements from another 5 patients who underwent nonpulsatile CPB. Although the pulse pressure measured in the circuit was 180 mm Hg on average, the pressure in the femoral artery was only 15 to 40 mm Hg with a mean of 20 mm Hg. In the same patients, 60 to 80 mm Hg pulse pressure was obtained with IABP. The pulse pressure obtained with the Delphin pump was not more than that obtained with the Terumo pump. There were no significant differences in percents of preoperative levels of platelet counts (pulsatile, 87.6 +/- 15.8% and nonpulsatile, 72.4 +/- 40.6%), free hemoglobin (pulsatile, 18 +/- 8 mg/dl and nonpulsatile, 25 = 7 mg/dl), and beta-TG (pulsatile 298 +/- 28 ng/ml and nonpulsatile, 312 +/- 143 ng/ml). In conclusion, although the pulsatile mode of the Terumo centrifugal pump did not exhibit any adverse effects hematologically, the pulse pressure obtained was unsatisfactorily small, mainly because of dumping caused by the perfusion cannula.

Angina Pectoris↗
PubMed1997

Effects of nonanal, trans-2-nonenal and 4-hydroxy-2,3-trans-nonenal on cyclooxygenase and 12-lipoxygenase metabolism of arachidonic acid in rabbit platelets.

The effects of nonanal, trans-2-nonenal and 4-hydroxy-2,3-trans-nonenal on the formation of thromboxane B2 (TXB2), 12-hydroxy-5,8,10-heptadecatrienoic acid (HHT) and 12-hydroxy-5,8,10,14-eicosatetraenoic acid (12-HETE) from exogenous arachidonic acid in washed rabbit platelets were examined. Nonanal and trans-2-nonenal at concentrations ranging from 0.25 to 2 microM inhibited TXB2, HHT and 12-HETE formation, reducing the amounts of these three arachidonic acid metabolites by 50% at nonanal and trans-2-nonenal concentrations of approximately 0.25 microM. The inhibition of TXB2, HHT and 12-HETE formation induced by 4-hydroxy-2,3-trans-nonenal (50% inhibition by 4-hydroxy-2,3-trans-nonenal at a concentration of approximately 100 microM) was 400 times weaker than that induced by nonanal and trans-2-nonenal. These results suggest that nonanal and trans-2-nonenal can be modulators of platelet arachidonic acid metabolism by affecting the activity of cyclooxygenase and 12-lipoxygenase.

Aldehydes↗
PubMed1997

[Effects of voluntary exercise on nonspecific immunological mechanisms in mice].

We studied the effects of voluntary exercise on nonspecific immunological mechanisms in mice. In this study, 7 week old male ICR mice were divided into two groups: a non-exercise group (control) and a group given voluntary exercise (Vex group). Each mouse of the Vex group was kept in an individual cage equipped with a voluntarily revolving wheel that the mouse had free access to. The duration of voluntary exercise was 3 days per week for 8 weeks. The following results were obtained: 1) After 8 weeks of voluntary exercise, food consumption, the weight of the anterior tibialis muscle and succinate dehydrogenase activity in the anterior tibialis muscle increased significantly in the Vex group compared to the control group. 2) By means of the carbon clearance method, phagocytosis of the reticuloendothelial system was increased in the Vex group. 3) Glucose consumption capacity and O-2 production capacity of peritoneal macrophages (M phi) were significantly increased in the Vex group compared to the control group. 4) The acid phosphatase (APH), beta-glucuronidase (GLU) and lactate dehydrogenase (LDH) activities of peritoneal M phi increased significantly in the Vex group. 5) Concanavalin A (Con A)-induced cell proliferation in the spleen was high in the Vex group. Based on the above findings, it may be surmised that voluntary exercise enhances nonspecific immunological mechanisms and thereby improves the host defense mechanisms in mice.

Animals↗
PubMed1997

Japanese experience with micropremies weighing less than 600 grams born between 1984 to 1993.

The viability limit defined by the Japanese Eugenic Protection Act was amended from 24 to 22 completed weeks of gestation in 1991. To testify if the amendment is appropriate, we conducted a survey on the mortality and morbidity rates of infants less than 600 g born in Japan between 1984 to 1993. Questionnaires were mailed to 205 hospitals with neonatal intensive care units (NICUs) and 165 (80%) responded. Of 1655 infants <600 g birth weight and admitted to the NICUs included in this survey, 457 (28%) survived to hospital discharge. The survival rates of infants born <24 weeks and >==24 weeks of gestation were 17% (128/748) and 36% (329/903), respectively; and of infants <500 g and 500 to 599 g at birth were 16% (82/510) and 32% (375/1145), respectively. None of the infants <==20 weeks of gestational age and <==350 g at birth survived, but 4% (2/49), 12% (27/218), 21% (99/474), and 34% (131/381) born at 21, 22, 23, and 24 weeks of gestation survived, respectively. The majority (68%) died within 1 week after birth and only 10% died after the neonatal period. The main causes of death were: acute respiratory failure (33%), intraventricular hemorrhage (20%), infection (16%), and heart failure (10%). Of 457 survivors, 65% were free from handicaps. The incidence of mental retardation (DQ < 70), visual disturbance, and CP were 15%, 14%, and 11%, respectively. Admission of micropremies to NICU increased markedly after the amendment of the Eugenic Protection Act, despite a marked decline in birth rate. The survival rate increased from 22% to 33% after generalized use of surfactant in 1988, but the handicap rate (35%) among survivors remained unchanged. The new viability limit of 22 complete weeks of gestation was feasible, since survival of less than 22 weeks was exceptional while survival of 22 to 23 weeks was 18%.

Cause of Death↗
PubMed1997

Transcatheter arterial ablation of aldosteronomas with high-concentration ethanol: preliminary and long-term results.

OBJECTIVE: The purpose of this study was to evaluate the efficacy of transcatheter arterial ablation (TAA) of aldosteronomas with high-concentration ethanol (HCE). MATERIALS AND METHODS: From August 1992 to August 1995, 18 patients with unilateral aldosteronoma, three men and 15 women, 28-65 years old, were treated by TAA with HCE. A single dose (0.2-7.0 ml) of HCE was selectively infused into the feeding arterial branches of the aldosteronoma using a microcatheter and the coaxial technique. The 18 patients underwent 31 TAA procedures. RESULTS: Ablation of the aldosteronoma was monitored by measuring plasma levels of aldosterone and was successful in 15 (83%) of 18 patients. The remaining three patients underwent surgery because results of TAA were insufficient. The destructive effect of ablation by HCE has persisted for 7-38 months (mean, 20 months) in 14 patients. Although one patient had recurrence of symptoms 15 months after the initial TAA, normalization of plasma levels of aldosterone continued for 3 months after TAA was repeated. No severe complications occurred in any of the 18 patients. However, back pain (18 of 18), slight fever (nine of 18), pleural effusion (two of 18), and labile changes in blood pressure (one of 18) were noted in patients 1-7 days after the procedure. CONCLUSION: TAA of aldosteronoma with HCE is an alternative to open adrenalectomy.

Adenoma↗
PubMed1997

Laboratory evaluation of a new membrane oxygenator with a built-in hemoconcentrator.

In order to facilitate the handling of cardiopulmonary bypass (CPB) and simplify the circuit, we have developed a new membrane oxygenator with a hemofiltration function. The hollow fiber units for gas exchange and hemofiltration were combined in concentric circles in a cylindrical housing. The total priming volume was 190 ml. Because we used a silicon-coated hollow fiber membrane for gas exchange, this oxygenator was completely resistant to serum leakage. The gas exchange and hemofiltration sections both have a blood-outside flow configuration. All blood flows in a radial direction from around the central core to the surrounding hollow fiber units, first to the hemofiltration portion and then to the gas exchange section. Filtered fluid was easily collected through a stopcock mechanism. The oxygen transfer rate was 312 ml/min at a blood flow rate of 6 L/min, and the ultrafiltration rate was 3.5 L/hour at a blood flow rate of 4 L/min with 25% hematocrit and 200 mmHg transmembrane pressure in an in vitro study. The pressure drop was 62 mmHg at a blood flow rate of 4 L/min. We found no adverse effects in an in vivo study using a mongrel dog. In conclusion, this durable combined device could achieve excellent and simplified hemoconcentration by having all the blood in the unit flow through the hemofiltration portion, and may be useful not only in CPB during open heart surgery, but also in extracorporeal membrane oxygenation.

Animals↗
PubMed1997

Scintigraphic assessment of therapeutic success in aldosteronomas treated by transcatheter arterial embolization using absolute ethanol.

UNLABELLED: Adrenocortical scintigraphy was examined as an indicator of therapeutic success in aldosteronomas treated by transcatheter arterial embolization (TAE) with absolute ethanol (AE). METHODS: Adrenocortical scintigraphy was performed 7 days after intravenous injection of 37 MBq 131I-6-beta-iodomethyl-19-norcholesterol before and after TAE. Complete or incomplete therapeutic success was determined by periodic measurements of the levels of plasma aldosterone and correlated with the scintigraphic results. RESULTS: The aldosteronoma was visualized as a hot nodule in nine patients and a warm nodule in one patient before TAE. Scintigraphy showed a hot, residual hot or warm nodule on seven occasions (six occasions after the first TAE and one occasion after the second TAE) when the techniques were incompletely successful and disappearance on seven occasions when success was achieved (three occasions after the first TAE and one occasion after the second TAE). Of the seven occasions when TAE was unsuccessful, four patients received the second or third TAE to result in complete destruction of the aldosteronoma; three patients underwent unilateral adrenalectomy. CONCLUSION: Adrenocortical scintigraphy can correctly predict the effect of TAE on aldosteronomas and is a valuable indicator for decisions on the necessity of repeated TAE or adrenalectomy.

Adosterol↗
PubMed1997

Localization of parathyroid glands using technetium-99m-tetrofosmin imaging.

UNLABELLED: Preoperative localization of hyperactive parathyroid glands is useful to minimize operative time and reduce patient morbidity. This investigation compared the sensitivity of radionuclide imaging with 99mTc tetrofosmin with that of ultrasonography and magnetic resonance (MR) imaging in patients with hyperparathyroidism. METHODS: Twenty-six patients with primary (n = 7) or secondary (n = 19) hyperparathyroidism were imaged with 99mTc tetrofosmin, ultrasound and MR imaging of the neck and thorax to localize the lesions. The presence of hyperparathyroidism was identified by an intact parathyroid hormone in vitro assay. The parathyroid/normal thyroid tissue activity ratio was calculated for all patients with evidence of an abnormality on tetrofosmin images. Pathological findings were compared with the results of imaging in 18 of the 26 patients who underwent parathyroidectomy. RESULTS: Technetium-99m tetrofosmin scans demonstrated focal uptake in 46 glands of 26 patients. The uptake was categorized as slight in 78.3% (36/46) and intense (parathyroid/normal thyroid tissue activity ratio, > 1.4) in 21.7% (10/46). Ultrasonography and MR imaging identified 44 and 47 glands, respectively, in these patients. Eleven of the 18 patients who underwent parathyroidectomy within 1 mo after tetrofosmin imaging had hyperplastic glands, while 7 had parathyroid adenomas. Tetrofosmin imaging successfully localized 7 of 7 (100%) adenomas and 27 of 37 (73.0%) hyperplastic glands. The sensitivities of each technique for localizing abnormal parathyroid glands were 77.3% (34/44) for tetrofosmin imaging: 68.2% (20/44) for ultrasonography: and 68.2% (30/44) for MR imaging. Technetium-99m tetrofosmin uptake ratio in the 18 patients with surgical exploration was not proportional to several oxyphil cells. CONCLUSION: Technetium-99m tetrofosmin parathyroid imaging may be useful for localizing abnormal glands in patients with primary and secondary hyperparathyroidism. The sensitivity of 99mTc tetrofosmin parathyroid imaging was high as compared to ultrasonography or MR imaging. The prolonged retention of tetrofosmin may not depend on the number of mitochondria-rich oxyphil cells.

Adenoma↗
PubMed1997

Neonatal hypoglycemia in infants with intrauterine growth retardation due to pregnancy-induced hypertension.

The early-onset type (onset earlier than 28 gestational weeks) of pregnancy induced hypertension (PIH) has the clinical characteristics of a high incidence of intrauterine growth retardations (IUGR), fetal distress, neonatal hypoglycemia and hypertensive disposition. Moreover, the infants from early-onset type of PIH mothers showed a statistically significant higher incidence of neurological handicap (cerebral palsy, mental retardation and epilepsy) than late onset type. The infants with a neurological handicap had severe IUGR and intractable hypoglycemia in the early neonatal period, probably due to low storage of glucose in the liver and fetal hypoxia. Appropriate perinatal management, including proper evaluation of fetal well-being and good timing of delivery, could improve the outcome of infants from early-onset type of PIH mothers.

Anthropometry↗
PubMed1997

Follow-up study of neonatal hypoglycemia.

A follow-up study was done on the neurological handicap and intellectual development of high-risk infants with neonatal hypoglycemia. The frequency of neonatal hypoglycemia in high-risk infants is 8.6%, and the incidence of a major neurological handicap in high-risk infants with neonatal hypoglycemia is 11%. Risk factors for the handicap group are very low birthweight, intrauterine growth retardation, perinatal asphyxia and mothers with pregnancy-induced hypertension. Average DQ at 1.5 and 2.5 years and IQ at 4 and 6 years of very low birthweight infants with neonatal hypoglycemia showed no significant difference, in contrast to the control group.

Central Nervous System Diseases↗
PubMed1997

Inhibition of rabbit gastric glucosamine synthetase activity by Cu2+, Zn2+ and Se4+.

The effects of Fe2+, Cu2+, Zn2+ and Se4+ on the activity of glucosamine synthetase, the rate-limiting enzyme of mucus synthesis, in rabbit gastric corporal mucosa were examined. Cu2+, Zn2+ and Se4+ inhibited the glucosamine synthetase activity at concentrations ranging from 1 to 10 microM (Cu2+, 8-98% inhibition; Zn2+, 10-99% inhibition; Se4+, 32-89% inhibition). The inhibitory effects of these three ions were much stronger than that of UDP-N-acetylglúcosamine known as a representative inhibitor of the glucosamine synthetase activity (10 microM, 52% inhibition). Fe2+ had no significant effect on the glucosamine synthetase activity up to 100 microM. These results suggest that Cu2+, Zn2+ and Se4+ can be potent inhibitors of gastric glucosamine synthetase activity.

Animals↗