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Biomedical subjects

Y Nakata

Publications and source records attributed to Y Nakata.

At least 109 records · Page 6Linked to original sources
PubMed1999

Xenon suppresses the hypnotic arousal in response to surgical stimulation.

STUDY OBJECTIVE: To evaluate the suppressive effects of xenon (Xe) on hypnotic arousal at skin incision. DESIGN: Prospective, randomized study. SETTING: Operating rooms at a university hospital. PATIENTS: 35 ASA physical status I and II patients presenting for elective lower abdominal surgery. INTERVENTIONS: Patients were randomly assigned to receive one of the following regimens: 1.3 minimum alveolar concentration (MAC) isoflurane, 1.3 MAC sevoflurane, 0.7 MAC Xe with 0.6 MAC sevoflurane, 1 MAC Xe with 0.3 MAC sevoflurane, or 0.7 MAC nitrous oxide (N2O) with 0.6 MAC sevoflurane (n = 7 each group). MEASUREMENTS AND MAIN RESULTS: The bispectral index (BIS) was measured at baseline, during anesthesia, and after skin incision. BIS increased significantly at skin incision from the values noted during anesthesia in the sevoflurane and N2O groups, whereas it remained stable at incision in the other three groups (mean change in BIS: 0 +/- 9 for isoflurane, 15 +/- 8 for sevoflurane, 5 +/- 6 for 0.7 MAC Xe, 4 +/- 11 for 1 MAC Xe, and 9 +/- 5 for N2O). CONCLUSIONS: Unlike N2O, Xe was able to suppress hypnotic arousal in response to surgical stimulation when administered with sevoflurane.

Abdomen↗
PubMed1999

Cost analysis of xenon anesthesia: a comparison with nitrous oxide-isoflurane and nitrous oxide-sevoflurane anesthesia.

STUDY OBJECTIVE: To determine the cost of xenon (Xe) anesthesia in relation to the anesthetic duration by conducting a cost analysis of this relatively expensive inhaled anesthetic. DESIGN: Cost analysis based on the literature on Xe anesthesia. SETTING: Anesthetic simulation based on data obtained in the operating rooms at a university hospital. PATIENTS: A 40-year-old, ASA physical status I adult patient model weighing 70 kg, undergoing elective minor surgery with endotracheal intubation and mechanical ventilation. INTERVENTIONS: Anesthesia was given in the following four techniques: 1) closed-circuit technique with Xe; 2) closed-circuit technique with nitrous oxide (N2O)-isoflurane; 3) semi-closed technique with N2O-isoflurane; and 4) semi-closed technique with N2O-sevoflurane. MEASUREMENTS AND MAIN RESULTS: Cost of each anesthetic technique was compared in U.S. dollars. The cost of Xe anesthesia was consistently higher than that of N2O-isoflurane or N2O-sevoflurane (for 240-min anesthesia; $356 with Xe, $52 with closed-circuit N2O-isoflurane, $94 with semi-closed N2O-isoflurane, and $84 with semi-closed N2O-sevoflurane). The major cost of Xe anesthesia was a result of the cost of priming and flushing; the cost of Xe used for its anesthetic effects was comparable with the other semi-closed techniques after 240 minutes. CONCLUSIONS: For Xe to be widely used in routine anesthesia, the methods of minimizing the amount of Xe necessary for priming and flushing must be developed.

Adult↗
PubMed1999

Production and some properties of salt-tolerant beta-xylosidases from a shoyu koji mold, Aspergillus oryzae in solid and liquid cultures.

Beta-xylosidase production from a shoyu (soy sauce) koji mold, Aspergillus oryzae HL15, cultured in solid and liquid media was examined and some properties of the enzymes were studied. Three beta-xylosidases (Xy11, Xy12 and Xy13) were easily extracted with 0.5% NaCl from a solid medium and purified homogeneously on SDS-PAGE by chromatography. On the other hand, in a liquid medium, A. oryzae HL15 produced mainly cell-wall-bound beta-xylosidases which could not be extracted with 0.5% NaCl or any detergent. Cell-wall-bound beta-xylosidases, Xy11-CB and Xy12-CB, were liberated by digestion of mycelia with Yatalase and purified to a homogeneous state on SDS-PAGE by HPLC column chromatography. Four beta-xylosidases (Xy11, Xy12, Xy11-CB and Xy12-CB) exhibited not only high activity at high NaCl concentrations, but also similar properties; on the other hand, Xy13 differed in terms of thermostability and halophilic properties. The salt tolerance of beta-xylosidases in A. oryzae suggests that these enzymes are highly active and involved in releasing xylose in shoyu moromi mash.

Journal Article↗
PubMed1999

Increased c-Fos/activator protein-1 confers resistance against anergy induction on antigen-specific T cell.

We have studied the contribution of c-Fos/activator protein-1 (AP-1) to antigen-specific T cell response with reference to T cell anergy by increasing c-Fos/AP-1 in vivo and in vitro. First, after injection of a high dose of staphylococcus enterotoxin B (SEB), clonal deletion of SEB-reactive V(beta)8(+) CD4 T cells occurred both in control B6 and H2-c-fos transgenic (fos) mice, whereas proliferation of T cells against SEB was profoundly depressed in B6 but not in fos mice. Second, the keyhole limpet hemocyanin-specific CD4 T(h)1 cell clone produced decreasing amounts of IL-2 in response to increasing amounts of concanavalin A (Con A) in vitro, whereas the decrease was less significant in the T(h)1 clones stably transfected with c-fos gene. Electrophoretic mobility shift assay with nuclear protein from the transformants showed that overexpression of the c-fos gene compensated the amounts of AP-1 in the nuclei of Con A-treated T(h)1 clones. Thus, increased c-Fos/AP-1 confers resistance against anergy induction on antigen-specific T cells.

Animals↗
PubMed1999

CAG repeat length in the androgen receptor gene of infertile Japanese males with oligozoospermia.

We analysed the CAG repeat length in exon 1 of the androgen receptor gene in 59 idiopathic Japanese infertile males with oligozoospermia; 36 fertile males were also analysed as controls. The number of CAG repeats in infertile males ranged from 14 to 32 (mean 21.2+/-4.2), whereas the number of CAG repeats in fertile males ranged from 16 to 31 (mean 21.4+/-3.5). Among infertile males, six possessed a short form of 14 CAG repeats and three possessed 15 CAG repeats. On the other hand, fertile males did not possess the short form of 14 or 15 CAG repeats. The incidence of infertile males with 14 and 15 CAG repeats was significantly higher (P<0.05) than that of fertile males. Although the sample size is small, the results suggest that the reduction of CAG repeats in exon 1 of the androgen receptor is closely related to impaired spermatogenesis in infertile Japanese males.

Adult↗
PubMed1999

Expression of recombinant human zona pellucida protein 2 and its binding capacity to spermatozoa.

The human zona pellucida (ZP) is composed of three major glycoproteins: ZP1, ZP2, and ZP3. The aim of this study was to clarify the role of ZP2 by focusing on the polypeptide structure. We produced in Escherichia coli a recombinant human ZP2 protein (rec-hZP2) corresponding to amino acid sequence 1-206 of the mature protein. The final yield of rec-hZP2 protein was 80 microg/ml Luria Broth medium. After 2-h incubation of human spermatozoa with rec-hZP2 in vitro, an immunofluorescent study indicated that rec-hZP2 bound only to acrosome-reacted spermatozoa. The binding site migrated from the acrosome to the midpiece of the spermatozoa. Rabbit and mouse antisera produced against rec-hZP2 stained native human ZP in the immunofluorescent study, and significantly blocked human sperm binding and penetration into human ZP as compared to control values. The N-terminal polypeptide portion of human ZP2 was shown to contain a binding site for acrosome-reacted spermatozoa and to play an important role in secondary sperm binding and penetration into the ZP.

Acrosome↗
PubMed1999

Platelet hyporeactivity in young infants during cardiopulmonary bypass.

UNLABELLED: Platelet dysfunction is one of the most important factors contributing to a postoperative hemorrhagic diathesis in children with congenital heart disease undergoing operations requiring cardiopulmonary bypass (CPB). However, very little is known about the influence of CPB on platelets in neonates and young infants. We studied 16 patients--8 young infants (<2 mo old) and 8 children (>12 mo old)--with congenital heart disease undergoing CPB. Surface density of an important platelet adhesive receptor, glycoprotein Ib, and degree of platelet activation, indicated by p-selectin positivity, were measured by whole blood flow cytometry in samples obtained at seven time points during the operations. We found that the percentage of p-selectin-positive platelets increased significantly in children, but not in young infants, during CPB. The young infant group exhibited a significantly smaller reduction of glycoprotein Ib than the child group during CPB (21.0% +/- 12.0% vs 32.7% +/- 18.1%; P < 0.05). Lack of CPB-induced increase of p-selectin and a smaller decrease of glycoprotein Ib in young infants in the current study suggest reduced platelet reactivity in young infants and neonates during CPB. The clinical significance of the reduced platelet reactivity in young infants and neonates remains to be determined. IMPLICATIONS: Platelets of young infants are less reactive than those of children during cardiopulmonary bypass, as determined by the cardiopulmonary bypass-induced alterations in platelet membrane adhesive receptors.

Age Factors↗
PubMed1999

Effects of xenon on hemodynamic responses to skin incision in humans.

BACKGROUND: The authors evaluated the hemodynamic suppressive effects of xenon in combination with sevoflurane at skin incision in patients undergoing surgery. METHODS: Forty patients were assigned randomly to receive one of the following four anesthetics: 1.3 minimum alveolar concentration (MAC) sevoflurane, 0.7 MAC xenon with 0.6 MAC sevoflurane, 1 MAC xenon with 0.3 MAC sevoflurane, or 0.7 MAC nitrous oxide with 0.6 MAC sevoflurane (n = 10 each group). Systolic blood pressure and heart rate were measured before anesthesia, before incision, and approximately 1 min after incision. RESULTS: The changes in hemodynamic variables in response to incision were less with sevoflurane in combination with xenon and nitrous oxide than with sevoflurane alone. Changes in heart rate (in beats/min) were 19+/-11 (+/- SD) for sevoflurane alone, 11+/-6 for 0.7 MAC xenon-sevoflurane, 4+/-4 for 1 MAC xenon-sevoflurane, and 8+/-7 for nitrous oxide-sevoflurane. Changes in systolic blood pressure were 35+/-18 mmHg for sevoflurane alone, 18+/-8 mmHg for 0.7 MAC xenon-sevoflurane, 16+/-7 mmHg for 1 MAC xenon-sevoflurane, and 14+/-10 mmHg for nitrous oxide-sevoflurane. CONCLUSIONS: Xenon and nitrous oxide in combination with sevoflurane can reduce hemodynamic responses to skin incision compared with sevoflurane alone. One probable explanation may be that xenon has analgesic properties similar to those of nitrous oxide, although the exact mechanism is yet to be determined.

Adult↗
PubMed1999

Effects of xenon on the performance of various respiratory flowmeters.

BACKGROUND: The anesthetic gas xenon has distinctly different physical properties compared with air, nitrous oxide, or oxygen. This led us to predict that xenon would affect the performance of commercially available flowmeters. METHODS: Flow was generated by an anesthesia ventilator connected to a lung simulator via a semiclosed breathing circuit. With the system filled with air or with various concentrations of xenon or nitrous oxide in a balance of oxygen, the tidal volume was measured with two rotating vanes, a Pitot tube, a variable-orifice flowmeter, and two constant-temperature hot-wire flowmeters. RESULTS: Although xenon minimally affected both rotating vane flowmeters, it caused the Pitot tube and the variable-orifice flowmeters to overread in proportion to the square root of the density of the gas mixture used (xenon is 4.6 times more dense than air). In contrast, the hot-wire anemometers underread with xenon; for example, their readings in the presence of 45% and 70% xenon were less than 10% of those displayed when air was used. Nitrous oxide minimally affected all the flowmeters except the variable-orifice device. The Pitot flowmeter was also affected, but only when its gas analyzer port was open to the ambient air so that it no longer corrected its readings for changes in gas composition. In these cases, nitrous oxide produced overreadings in the same manner as did xenon. CONCLUSION: Among the four types of flowmeters studied, only the rotating-vane type is sufficiently accurate for use during anesthesia with xenon.

Anesthetics, Inhalation↗
PubMed1999

Anesthetic doses of sevoflurane to block cardiovascular responses to incision when administered with xenon or nitrous oxide.

BACKGROUND: The authors' previous study demonstrated that xenon (Xe) and nitrous oxide (N2O) in combination with sevoflurane can attenuate cardiovascular responses to skin incision. To quantitatively evaluate their suppressive effects on cardiovascular responses, the authors compared the MAC-BAR (minimum alveolar concentration that blocks adrenergic or cardiovascular response to incision) values of sevoflurane when administered with Xe or N2O. METHODS: Forty-three patients received sevoflurane with one of three anesthetics; 1 MAC Xe, 0.7 MAC Xe and 0.7 MAC N2O. The MAC-BAR of sevoflurane was determined in each anesthetic using the "up and down" method. The response was considered positive if the heart rate or mean arterial pressure increased 15% or more. The end-tidal sevoflurane concentration given to the next patient was increased or decreased by 0.3 MAC if the response was positive or negative in the previous patient, respectively. The MAC-BAR was calculated as the mean of four independent cross-over responses. RESULTS: The MAC-BAR of sevoflurane, including the contribution of Xe or N2O, was 2.1+/-0.2 MAC and 2.7+/-0.2 MAC when administered with 1 MAC and 0.7 MAC Xe, respectively, and 2.6+/-0.4 MAC when administered with 0.7 MAC N2O (mean +/- SD). CONCLUSIONS: Although 1 MAC Xe has a more potent suppressive effect on cardiovascular responses to incision than 0.7 MAC Xe or N2O, Xe and N2O have a similar suppressive effect at 0.7 MAC.

Adult↗
PubMed1999

Triolein-induced pulmonary embolization and increased microvascular permeability in isolated perfused rat lungs.

BACKGROUND: The pathophysiologic mechanism of the fat embolism syndrome is poorly understood. This study was designed to determine the effects of fat emboli on pulmonary vasculature. METHOD: Triolein was infused into isolated rat lungs perfused with Krebs-Henseleit buffer. Pulmonary arterial pressure and microvascular permeability (Kf) were measured at baseline and 20 minutes after the triolein infusion. RESULT: The 99% triolein produced dose-dependent increases in both pulmonary arterial pressure and Kf. The 65% triolein, containing free fatty acid, resulted in a greater increase in Kf. Pretreatment with indomethacin attenuated the increase in Kf after 65% triolein but not after 99% triolein. CONCLUSION: Pure triolein induced mainly embolization in the pulmonary vasculature, and 65% triolein caused embolization and subsequently increased vascular permeability, which are, at least in part, mediated by the action of cyclooxygenase products. Free fatty acids might induce permeability edema by means of a cyclooxygenase-dependent mechanism. We conclude that triolein-induced increases in pulmonary arterial pressure and Kf in isolated rat lungs provides a useful model of acute lung injury by fat embolism.

1-Methyl-3-isobutylxanthine↗
PubMed1999

Runaway pacemaker caused by a stuck accelerometer.

We report a case of runaway pacemaker with a ventricular pacing rate of 190 beats/min. The runaway occurred when the accelerometer became stuck due to the magnet application during VVIR pacing. Runaways in modern pacemakers are particularly rare, but they do still occur. The best solution for this phenomenon is generator replacement.

Electrocardiography↗
PubMed1999

Expression of C-type natriuretic peptide during development of rat lung.

C-type natriuretic peptide (CNP), recently found to be secreted from vascular endothelial cells, is now viewed as a novel endothelium-derived relaxing peptide. However, the distribution and expression of CNP during cardiopulmonary development is unclear. To follow changes in the expression of CNP during lung development, we examined rat embryos and neonates using Northern blot analysis and in situ hybridization for CNP mRNA and radioimmunoassay and immunohistochemistry for CNP protein. A substantial expression of CNP mRNA was first detected on postnatal day 2, and it thereafter remained fairly steady. The level of CNP protein also increased rapidly after postnatal day 1, reaching a settled level on postnatal day 4. CNP protein and mRNA were detected in the endothelium and smooth muscle cells of blood vessels and in bronchial airway and alveolar epithelia. Immunoreactivity for CNP protein in the endothelium of blood vessels increased to an intense level after the saccular stage. These results suggest that the changes in CNP levels may be related to the occurrence of pulmonary vasodilation after birth.

Animals↗
PubMed1999

Analysis of heart rate variability during head-up tilt testing in a patient with idiopathic postural orthostatic tachycardia syndrome (POTS).

A 16-year-old boy was diagnosed with idiopathic postural orthostatic tachycardia syndrome (POTS) during head-up tilt testing. During a passive tilt, the patient's heart rate (HR) increased by 30 beats/min within 5 min. After 25 min of tilting, his HR further increased to 133 beats/min and he began to complain of lightheadedness and weakness without hypotension. Power spectral analysis of HR variability during the tilt test revealed that the ratio of low and high frequency powers increased with the onset of orthostatic intolerance. Propranolol (10mg every morning) dramatically alleviated his clinical symptoms, and he has been asymptomatic with gaining weight after discontinuing his crowded train commuting.

Adolescent↗
PubMed1999

Acute performance of steroid-eluting screw-in leads for atrial free wall pacing.

The aim of this study was to clarify the acute performance of steroid-eluting screw-in leads in comparison with that of nonsteroid screw-in leads for atrial free wall pacing. In 114 cases (68 males, 46 females, average age 70 years) with atrial free wall pacing by screw-in leads, pacing thresholds and P-wave amplitudes were compared at the time of implantation and 1 week later between 68 cases of nonsteroid and 46 cases of steroid-eluting screw-in leads. No significant differences were seen between the 2 groups at implantation in either voltage or current thresholds measured at pulse widths of 0.1, 0.3, 0.6, 1.0, 2.0 ms, or P-wave amplitudes. Pulse width thresholds at outputs of 2.5 V and 5.0 V were significantly lower for steroid leads 1 week after implantation (2.5 V: 0.34+/-0.27 ms nonsteroid vs. 0.12+/-0.08 ms steroid, p<0.001; 5.0 V: 0.12+/-0.08 ms nonsteroid vs. 0.06+/-0.02 ms steroid, p<0.01). P-wave amplitudes after 1 week were significantly higher for steroid leads (2.6+/-0.7 mV nonsteroid vs 3.0+/-1.2 mV steroid, p<0.001). Threshold rise, including pacing failure, was observed in 15 (22%) of the non-steroid leads, but in only 1 (2%) of the steroid leads. In conclusion, steroid-eluting screw-in leads suppress the acute rise of pacing thresholds in the right atrial free wall and their acute performance is better than that of non-steroid leads. These results suggest that appropriate low-output atrial pacing is feasible immediately after implantation.

Aged↗
PubMed1999

[Effect of aged garlic extract (AGE) on hyperglycemia induced by immobilization stress in mice].

The effect of aged garlic extract (AGE) on stress induced hyperglycemia was investigated using the immobilization stress model in mice. After the exposure to immobilization stress for 16 hr per day for 2 consecutive days, the adrenal glands of the mice hypertrophied, and their serum glucose level and corticosterone secretion became elevated, but insulin secretion did not change. These results suggest that the elevation of serum glucose was probably due to the stimulation of the pituitary-adrenocortical axis by the stress. Pretreatment of AGE (5 and 10 ml/kg, p.o.) significantly prevented adrenal hypertrophy, hyperglycemia and elevation of corticosterone, but did not alter serum insulin level. The efficacy of AGE was the same as that of diazepam (5 mg/kg, p.o.). From these results, it is suggested that AGE may prevent stress-induced hyperglycemia, which is the risk of suffering from diabetes mellitus and its progression.

Adrenal Glands↗
PubMed1999

[Functional characterization of a sigma receptor and its gene expression by haloperidol].

Sigma (sigma) receptors are expressed in the brain as well as endocrine and immune systems. Several antipsychotic drugs such as haloperidol and pentazocine can bind to the sigma receptor, which is believed to play important roles in the pathogenesis of schizophrenia by as yet unknown mechanisms. Two subtypes of sigma receptors (sigma 1 and sigma 2) have been identified, and the sigma 1 receptor was cloned. The chronic administration of haloperidol to guinea pigs produced a marked inhibition of the binding to sigma 1 receptor, but did not change sigma 2-receptor binding. Scatchard analysis demonstrated that the inhibition was due to a reduction in the number of binding sites without changes in the affinity. The treatment with haloperidol also did not affect sigma 1-receptor mRNA detected by the RNase protection assay. The treatment of rats with haloperidol inhibited sigma 1-receptor binding to a much lesser extent than that to guinea pigs. These finding suggest that haloperidol or its metabolite, reduced haloperidol, which is produced in greater quantity in humans and guinea pigs than in rats and mice, might influence protein translation or modification of sigma 1-receptor without changing the transcriptional activity. The mechanisms through which sigma receptors could be differently regulated in vivo by chronic treatment with haloperidol may contribute to the therapeutic efficacy of haloperidol.

Animals↗