Biomedical subjects

N Hirai

Publications and source records attributed to N Hirai.

At least 37 records · Page 2Linked to original sources

PubMed2000

Successful treatment of two patients with recurrent endometrial cancer by weekly paclitaxel.

OBJECTIVE: The aim of this study was to evaluate the toxicity and efficacy of weekly paclitaxel in patients with recurrent endometrial cancer. METHODS: Paclitaxel (70 mg/m(2) by 1-h infusion weekly) was administered to two patients with recurrent endometrial cancer of the lung. RESULTS: After 5 cycles, both patients with platinum-resistant disease achieved clinical partial responses confirmed by computed tomography (CT) scan. The serum CA125 levels of case 1 decreased to cut-off level. The response duration of both patients was 4 months. The toxicity was acceptable and probably less pronounced than that characterize of the standard tri-weekly schedules. CONCLUSION: Although conclusions regarding survival are premature, weekly paclitaxel might offer better quality of life during treatment.

Adenocarcinoma↗

PubMed2000

Suppression of gamma activity in the human medial temporal lobe by sevoflurane anesthesia.

We have reported the presence of continuous gamma (30-150 Hz) activity in the human medial temporal lobe (MTL). Since the MTL is involved in learning and memory, we speculated that MTL gamma activity is related to such higher brain functions. It is thus of interest to learn how this activity changes during different states of consciousness. In this study, we recorded electrocorticographic (ECoG) activity directly from the surface of the MTL after various doses of sevoflurane anesthesia. Five epileptic patients underwent electrode placement operations in which electrodes were attached to the surfaces of the MTL and the basal temporal lobe (BTL). Immediately following the operation ECoG was recorded from each patient under four concentrations of sevoflurane anesthesia (1.5, 2.0, 2.5 and 3.0%). Fast Fourier Transform (FFT) analysis was performed on the MTL ECoGs. Under the lowest sevoflurane concentration, MTL gamma activity was observed in all patients. However, gamma activity was progressively suppressed by increased concentrations of sevoflurane, in a dose-dependent manner. Sevoflurane has been known to reduce neuronal excitability in the rat hippocampus in vitro, probably by changing GABAergic inhibition. The reduction of MTL gamma in the present study may be the result of such a mechanism. Although memory function was not tested in this study, the amount of MTL gamma activity may be related to residual memory function during anesthesia.

Adolescent↗

PubMed2000

Allelochemicals of the tropical weed Sphenoclea zeylanica.

Nine plant growth inhibitors were isolated from the tropical weed Sphenoclea zeylanica, which shows allelopathic properties. Those compounds hitherto not reported from any plant source were the isomers of cyclic thiosulfinate, (1S,3R,4R)-(+)- and (1R,3R,4R)-(+)-4-hydroxy-3-hydroxymethyl-1,2-dithiolane-1-oxides, and (2R,3R,4R)-(-)- and (2S,3R,4R)-(+)-4-hydroxy-3-hydroxymethyl-1,2-dithiolane-2-oxides. These were named zeylanoxide A, epi-zeylanoxide A, zeylanoxide B and epi-zeylanoxide B, respectively. The absolute configurations at C-3 and C-4 were elucidated by chemical synthesis of both enantiomers from L- and D-glucose. Two of the inhibitors were secologanic acid and secologanoside. and three other inhibitors were by known secoiridoid glucosides formed as artifacts during extraction with methanol. The cyclic thiosulfinates and secoiridoid glucosides completely inhibit the root growth of rice seedlings at 3.0 mM. While the specific activity of the inhibitors was not high, since they accumulated to circa 0.61% S. zelanica by dry weight, this suggests that the inhibitors are nervertheless potent allelochemicals in this weed.

Lactuca↗

PubMed2000

The role of fixation point and subjects' readiness in the occurrence of express saccades as revealed by the self-initiation paradigm.

The role of fixation and the subjects' response preparedness in producing express saccades were explored in seven human subjects. The occurrence frequencies of the express saccades were compared in the overlap (continuous presentation of fixation point), gap (fixation point offset 0-400 ms prior to target onset) and no-fixation tasks under the conventional and self-initiation paradigms. In the latter paradigm, the subjects, when ready, touched a sensor in order to ignite the target lamp with a delay time of 0-400 ms (target onset delay time). Therefore, the subjects' response preparedness might be expected to be higher than that in the normal paradigm and equated in each subject at the time when the subjects touched a sensor regardless of the paradigms. Although express saccades were produced neither in the normal overlap nor in the normal no-fixation tasks, they could be produced at the rate of 24 and 48% in the overlap and no-fixation tasks under the self-initiation paradigm, respectively. The highest occurrence frequency of express saccades was obtained when the gap paradigm was combined with the self-initiation paradigm with a delay time of 100 ms (62%). The value was higher by 20% than in the normal gap task. At a target onset delay time of 0 ms under the self-initiation paradigm, the occurrence frequency of express saccades was higher in the overlap task than in the gap task. These results suggest that the subjects' response preparedness has a potentiality to produce express saccades without fixation point offset and that fixation point offset at the same time of the target stimulus onset has an interference, rather than facilitatory, influence on the generation of express saccades.

Adult↗

PubMed2000

Improvement of endothelial function and insulin sensitivity with vitamin C in patients with coronary spastic angina: possible role of reactive oxygen species.

OBJECTIVES: This study was designed to examine the effect of antioxidant supplementation on the endothelial function and insulin sensitivity in patients with coronary spastic angina (CSA). BACKGROUND: Insulin resistance may play a key role in coronary heart disease, and there is a possible link between acetylcholine-induced coronary vasoconstriction and hyperinsulinemia in patients with CSA. Endothelial dysfunction is present in the systemic arteries in CSA patients, and reactive oxygen species may cause inactivation of nitric oxide in these patients. METHODS: We measured flow-mediated dilation of the brachial artery using ultrasound technique in 22 patients with CSA and 20 control subjects. We also evaluated glucose tolerance using a 75-g oral glucose tolerance test and insulin sensitivity using steady-state plasma glucose (SSPG) methods in the same patients. RESULTS: The incidence of impaired glucose tolerance was higher in the CSA group than in the control group. Vitamin C infusion augmented flow-mediated dilation and decreased SSPG levels in the CSA group (from 3.27 +/- 0.77% to 7.00 +/- 0.59% [p < 0.001 by analysis of variance (ANOVA)] and from 177.3 +/- 13.3 to 143.1 +/- 14.9 mg/dl [p = 0.047 by ANOVA], respectively) but not in the control group (from 6.47 +/- 0.66% to 6.80 +/- 0.60% and from 119.8 +/- 11.7 mg/dl to 118.1 +/- 11.3 mg/dl, respectively). The steady-state plasma insulin levels were not affected by vitamin C infusion in either group. CONCLUSIONS: Vitamin C improves both endothelial function and insulin sensitivity in patients with CSA. Thus, reactive oxygen species and/or decreased nitric oxide bioactivity may play an important role in the genesis of both endothelial dysfunction and insulin resistance in patients with CSA.

Angina, Unstable↗

PubMed2000

Insulin resistance and endothelial dysfunction in smokers: effects of vitamin C.

Cigarette smoking impairs endothelial function and is one of the major risk factors for atherosclerosis and coronary heart disease. Insulin resistance is associated with major risk factors for atherosclerosis. We examined the effects of vitamin C on insulin sensitivity and endothelial function by measuring steady-state plasma glucose (SSPG) and flow-mediated dilation (FMD) of the brachial artery. We studied 16 current smokers with normal glucose tolerance, 15 nonsmokers with impaired glucose tolerance (IGT), and 17 nonsmokers with normal glucose tolerance as controls. Both SSPG and FMD were blunted in smokers and nonsmokers with IGT compared with controls. In smokers, vitamin C decreased SSPG (P < 0.01 by ANOVA) with decreasing plasma thiobarbituric acid-reactive substances (TBARS) (P < 0.05 by ANOVA) and improved FMD (P < 0.05 by ANOVA). Furthermore, vitamin C improved both SSPG (P < 0.005 by ANOVA) and FMD (P < 0.05 by ANOVA) in nonsmokers with IGT. SSPG, FMD, or TBARS in controls did not change after vitamin C infusion. There was a significant correlation between SSPG and FMD both in smokers and nonsmokers with IGT, whereas no correlation was observed in controls. In conclusion, both insulin sensitivity and endothelial function were impaired in smokers and nonsmokers with IGT and were improved by vitamin C. Thus increased reactive oxygen species play an important role in the pathogenesis of insulin resistance as well as endothelial dysfunction in smokers and nonsmokers with IGT.

Analysis of Variance↗

PubMed2000

Biosynthesis of abscisic acid by the non-mevalonate pathway in plants, and by the mevalonate pathway in fungi.

The biosynthetic pathways to abscisic acid (ABA) were investigated by feeding [1-(13)C]-D-glucose to cuttings from young tulip tree shoots and to two ABA-producing phytopathogenic fungi. 13C-NMR spectra of the ABA samples isolated showed that the carbons at 1, 5, 6, 4', 7' and 9' of ABA from the tulip tree were labeled with 13C, while the carbons at 2, 4, 6, 1', 3', 5', 7', 8' and 9' of ABA from the fungi were labeled with 13C. The former corresponds to C-1 and -5 of isopentenyl pyrophosphate, and the latter to C-2, -4 and -5 of isopentenyl pyrophosphate. This finding reveals that ABA was biosynthesized by the non-mevalonate pathway in the plant, and by the mevalonate pathway in the fungi. 13C-Labeled beta-carotene from the tulip tree showed that the positions of the labeled carbons were the same as those of ABA, being consistent with the biosynthesis of ABA via carotenoids. Lipiferolide of the tulip tree was also biosynthesized by the non-mevalonate pathway.

Abscisic Acid↗

PubMed2000

Triterpene phytoalexins from strawberry fruit.

Strawberry cv. Houkouwase is resistant to infection by Colletotrichum fragariae. The formation of antifungal compounds was observed in unripe fruit which had been wounded and inoculated with conidia of C. musae. Three antifungal compounds were isolated and identified as euscaphic acid, tormentic acid and myrianthic acid. Myrianthic acid inhibited the growth of C. musae at 3 microg, and euscaphic and tormentic acids showed inhibitory effects at 100 microg. A quantitative analysis of their contents showed that the triterpenes increased in wounded fruit, and in wounded and inoculated fruit, but not in non-treated fruit. These findings indicate that unripe fruit of Houkouwase produced the triterpenes as phytoalexins. The triterpene phytoalexins seem to be involved in the resistance of strawberry to the fungus.

Anti-Infective Agents↗

PubMed2000

Changes in the content and biosynthesis of phytoalexins in banana fruit.

Changes in the phytoalexin content in unripe fruit of banana, Musa acuminata, were analyzed after various treatments. The results show that level of hydroxyanigorufone started to increase 1-2 day after either wounding or inoculation with conidia of Colletotrichum musae. Inoculation followed by wounding induced the formation of many other phenylphenalenones. The accumulation of hydroxyanigorufone decreased, after its transient maximum, on ripening by exposure of the wounded fruit to ethylene. The level of production of hydroxyanigorufone in ripe fruit treated by wounding and/or by inoculation was much lower than that in unripe fruit. 2-Aminooxyacetic acid, an inhibitor of phenylalanine ammonia-lyase (PAL), inhibited the accumulation of hydroxyanigorufone in wounded fruit, and the PAL activity increased after wounding and ethylene treatment, respectively. Feeding experiments with [1-(13)C] and [2-(13)C]cinnamic acids, and [2-(13)C]malonate show that two molecules of cinnamic acid and one of malonate were incorporated into each molecule of hydroxyanigorufone. The phytoalexins isolated from fruit to which deuterated hydroxyanigorufone and irenolone had been administered revealed that 2-(4'-hydroxyphenyl)-1,8-naphthalic anhydride was biosynthesized from hydroxyanigorufone rather than from irenolone.

Chromatography, High Pressure Liquid↗

PubMed2000

[Usefulness of selective cerebral angiography by transradial approach].

Transradial angiography has recently emerged as an alternative to the transfemoral or transbrachial approach, especially for coronary procedures. However, there have been few studies on cerebral angiography using the transradial approach. The purpose of this study was to assess the outcomes, complications, and limitations of selective cerebral angiography via the transradial approach. Selective cerebral angiography by the right transradial approach using 100-cm-long 4-F catheters was performed in 83 patients. Using five types of catheters, the success rates of selective catheterization to the right vertebral artery, right common carotid artery, left common carotid artery, and left vertebral artery were 40/44 (91%), 68/68 (100%), 62/62 (100%), and 14/25 (56%), respectively. Puncture failed in one patient, and a guidewire could not be introduced beyond the radial artery loop in one patient. Radial artery spasm occurred in one patient, but was relieved immediately after nitroglycerin injection through the sheath with side holes. Subcutaneous bleeding occurred in six patients, but no obvious hematomas were noted. Occlusion or stenosis of the radial artery occurred in five patients, but no ischemic symptoms were observed in any of the cases. This study suggested that selective cerebral angiography can be performed safely using the transradial approach.

Adolescent↗

PubMed2000

[Neoadjuvant chemotherapy with cisplatin and CPT-11 for advanced cervical cancer].

Neoadjuvant chemotherapy (NAC) is currently used for the treatment of advanced cervical cancer by many institutions. We investigated the value of NAC followed by radical surgery and/or radiotherapy for patients with locally advanced cervical cancer. Sixteen patients with stage Ib2-IIIb cervical cancer were enrolled in this study. CPT-11 (60 mg/m2) in 500 m/5% glucose was given intravenously on Days 1, 8, and 15, before cisplatin (60 mg/m2) in 500 ml normal saline. The treatment was repeated every 4 weeks for 2 or 3 cycles. All patients were evaluable for response and toxicity. Two achieved a clinical complete response (CR), 11 had a partial response (PR), 2 had no change (NC) and 1 had progressive disease (PD), for an overall response of 81.3%. Neutropenia was observed in 100% (> grade 3: 70.6%) and diarrhea was recorded in 55.9% (> grade 3: 5.9%). The combination of CPT-11 and cisplatin in locally advanced cervical cancer is thus an active regimen with a manageable toxicity as a neoadjuvant chemotherapy.

Adult↗

PubMed2000

Rapid change of platelet aggregability in acute hyperglycemia. Detection by a novel laser-light scattering method.

We examined the alteration of platelet aggregability in acute hyperglycemia during 75-gram oral glucose tolerance tests (OGTT). Twenty subjects underwent 75-gram OGTT and venous blood samples were obtained before (0 min), 60, 120 and 180 min postload. Platelet aggregability shown as the number of small platelet aggregates was measured with a novel laser-light scattering (LS) method. Platelet aggregability increased in parallel with both glucose and immunoreactive insulin (IRI) levels. The number of mean small aggregates at 60 min (12.30 +/- 1.10 X 10(4)) was significantly higher than the one at 0 min (8.32 +/- 0.88 x 10(4), p <0.001), 120 min (10.63 +/- 0.98 x 10(4), p <0.05) and 180 min (8.28 +/- 0.84 x 104, p <0.001) (mean +/- SEM). Small aggregates correlated positively with plasma glucose levels at 60 min postload (r = 0.67, p = 0.001) while not with IRI. It might be important to suppress transient hyperglycemia for preventing the onset of acute coronary syndromes that could be closely related to platelet hyperaggregability.

Acute Disease↗

PubMed1999

Beta-1 (10-20 Hz) cortical oscillations observed in the human medial temporal lobe.

During wakefulness, signals from subdural electrodes attached to the basal and medial temporal lobes of adult human epilepsy patients revealed a rhythmic oscillation in the beta-1 frequency range (10-20 Hz). This activity was more prominent in the medial than in the basal temporal cortex. We also observed simultaneous oscillations in alpha frequency activity in the medial and the basal temporal cortices. In an eyes-open condition, the alpha oscillation was attenuated, while the beta-1 oscillation in the medial temporal lobe was not. This is the first report that the beta-1 oscillation is present in the human medial temporal lobe. Since we recorded this activity from within the limbic system, beta-1 activity may be an analog of the hippocampal rhythmic slow activity observed in some animals.

Adult↗

PubMed1999

Association of plasma levels of activated protein C with recanalization of the infarct-related coronary artery after thrombolytic therapy in acute myocardial infarction.

Protein C is one of the most important antithrombotic components. After activation by the thrombin-thrombomodulin complex on endothelial cells, activated protein C (APC) inactivates factors Va and VIIIa, which leads to the inhibition of thrombin formation. We examined the association of plasma levels of APC with the responsiveness to coronary thrombolytic therapy of the infarct-related coronary artery in patients with acute myocardial infarction (AMI). Plasma levels of APC, thrombin-antithrombin III complex (TAT), and plasminogen activator inhibitor (PAI) activity were measured in 32 consecutive AMI patients who underwent coronary angiography followed by thrombolytic therapy, and compared to the measurements in 23 control subjects. On admission, APC levels (ng/mL) were significantly elevated in patients with AMI, as compared with controls (2.5+/-0.4 vs. 1.2+/-0.2, 1.3+/-0.2, respectively, p<0.01). At discharge, plasma levels in AMI patients decline to values not significantly different from those in controls. (1.2+/-0.2, 1.3+/-0.2, respectively). TAT levels (ng/mL) were different among the groups in a fashion similar to that of APC (14.1+/-3.1 on admission vs. 3.3+/-0.4 at discharge, 1.8+/-0.1 in the control subjects, respectively, p<0.01). PAI activity levels (IU/mL) were higher on admission than at discharge and higher than the control subjects (19.7+/-1.8 vs. 10.5+/-1.0, 5.4 +/- 0.7, respectively, p<0.01). Thirty-two patients with AMI were classified into two groups according to the results of thrombolysis: the success group (24 patients) and the failure group (eight patients). APC levels were higher in the failure group than in the success group (5.1+/-0.7 vs. 1.6+/-0.2, p<0.01). TAT levels were also higher in the failure group than in the success group (30.8+/-9.6 vs. 8.6+/-1.7, p<0.01). PAI activity levels (IU/mL) were lower in the failure group than in the success group (13.5+/-3.1 vs. 21.7+/-2.1, p<0.05). There were correlations between APC and TAT levels both on admission (r=0.75, p<0.0001) and at discharge (r=0.71, p<0.0001). Elevated APC was thought to correlate with increased thrombin generation in patients with AMI. This study demonstrated that there was a significant relation between plasma APC level and the responsiveness to thrombolytic therapy of the infarct artery. This study may also indicate that increased thrombin generation is a cause of the resistance to thrombolytic therapy.

Acute Disease↗

PubMed1999

Enhanced gamma (30-150 Hz) frequency in the human medial temporal lobe.

We performed fast Fourier transformation power spectral analysis of the electrocorticogram in human medial temporal lobe during wakeful rest in six epileptic subjects. Compared with the electrocorticogram wave in the basal temporal lobe, which showed monotonic decline of spectral power across the frequency axis, the electrocorticogram wave in the parahippocampal gyrus was enhanced (or did not decline) in the gamma frequency range (30-150 Hz) in all subjects. Although it has been suggested that electrical oscillations of the hippocampus have functional roles in higher brain functions, namely learning and memory, the knowledge of hippocampal oscillations is largely limited to animal studies. The present results demonstrate that fast frequency oscillation is also present in the human medial temporal lobe, which has been reported in animal hippocampi. They also demonstrate the importance of recording very fast field potentials in human electrocorticograms. This fast oscillation is likely to play important functional roles related to learning and memory, possibly to induce long-term potentiation in the human medial temporal lobe.

Action Potentials↗

PubMed1999

Improvement of endothelial vasomotor dysfunction by treatment with alpha-tocopherol in patients with high remnant lipoproteins levels.

OBJECTIVES: This study sought to examine whether oral intake of alpha-tocopherol, an antioxidant, could improve endothelium-dependent vasorelaxation in patients with high remnant lipoproteins levels. BACKGROUND: Remnant lipoproteins are known to be atherogenic and impair endothelium-dependent arterial relaxation, but the underlying mechanisms remain unclear. Oxidative stress is a common feature of various risk factors for atherosclerosis. METHODS: Flow-mediated vasodilation of the brachial artery during reactive hyperemia was examined by high resolution ultrasound technique before and at the end of 4 weeks treatment with oral administration of alpha-tocopherol acetate (300 IU/day) or placebo, which was randomly assigned, in 40 patients with high serum levels of remnants and in 30 patients with low remnants levels in the fasting state (>75th percentile and <25th percentile, respectively, of the distribution of remnants levels in 150 consecutive hospitalized patients). RESULTS: Before treatment, flow-mediated vasodilation was lower in patients with high remnants levels than in those with low levels (4.1 +/- 0.3% vs. 6.0 +/- 0.5%, p < 0.01). Treatment with alpha-tocopherol but not with placebo significantly increased flow-mediated dilation in patients with high remnants levels (7.5 +/- 0.4% after alpha-tocopherol vs. 4.2 +/- 0.4% after placebo, p < 0.01). In patients with low remnants levels, alpha-tocopherol was not effective. The beneficial effect with alpha-tocopherol in high remnants patients was associated with decrease in plasma levels of thiobarbituric acid reactive substances, an indicator of lipid peroxidation (6.6 +/- 0.3 nmol/ml before alpha-tocopherol vs. 4.6 +/- 0.3 after alpha-tocopherol, p < 0.05). CONCLUSIONS: Alpha-tocopherol improved impairment of endothelium-dependent vasodilation in patients with high remnants levels. The increase in oxidative stress may at least partly contribute to endothelial vasomotor dysfunction, in patients with high remnants levels.

Adult↗

PubMed1999

Hyperglycemia rapidly suppresses flow-mediated endothelium-dependent vasodilation of brachial artery.

OBJECTIVES: We examined whether endothelial dysfunction occurs when acute hyperglycemia is induced by oral glucose loading. BACKGROUND: Endothelial dysfunction has been shown to occur in patients with diabetes mellitus (DM), and chronic hyperglycemia is implicated as a cause of endothelial dysfunction. However, in many patients with Type 2 DM and in those with impaired glucose tolerance (IGT), fasting blood glucose may be within normal limits, and hyperglycemia occurred only post-prandially. METHODS: With ultrasound technique, we measured flow-mediated endothelium-dependent vasodilation during oral glucose tolerance test in 58 subjects: (17 patients with normal glucose tolerance [NGT], 24 with IGT, and 17 with type 2 DM). In addition, we measured the levels of thiobarbituric acid reactive substances (TBARS) and nitrite/nitrate. RESULTS: Flow-mediated vasodilation decreased after glucose loading (NGT: 7.53+/-0.40, 4.24+/-0.28 and 6.35+/-0.40, in fasting, at 1- and 2-h, respectively, IGT: 6.50+/-0.48, 1.40+/-0.41** and 4.00+/-0.47*, respectively; DM: 4.77+/-0.37, 1.35+/-0.38** and 1.29+/-0.29%**, respectively; *p < 0.01 vs. fasting, **p < 0.005 vs. fasting). The TBARS concentration increased in parallel with plasma glucose level in each group (NGT: 1.43+/-0.07, 2.03+/-0.12 and 1.80+/-0.12, respectively; IGT: 1.65+/-0.11, 2.46+/-0.12** and 1.94+/-0.08*, respectively; DM: 1.73+/-0.07, 2.34+/-0.08** and 2.47+/-0.09** nmol/ml, respectively; *p < 0.05 vs. fasting, **p < 0.01 vs. fasting). Glucose loading did not change nitrite/nitrate concentration in any of the groups. CONCLUSIONS: Hyperglycemia in response to oral glucose loading rapidly suppresses endothelium-dependent vasodilation, probably through increased production of oxygen-derived free radicals. These findings strongly suggest that prolonged and repeated post-prandial hyperglycemia may play an important role in the development and progression of atherosclerosis.

Acute Disease↗

PubMed1998

In situ synthesis of beta-glucan microfibrils on tobacco plasma membrane sheets.

A major concern in plant morphogenesis is whether cortical microtubules are responsible for the arrangement and action of beta-glucan synthases in the plasma membrane. We prepared isolated plasma membrane sheets with cortical microtubules attached and tested whether beta-glucan synthases penetrated through the membrane to form microfibrils and whether these synthases moved in the fluid membrane along the cortical microtubules. This technique enabled us to examine synthesis of beta-glucan as a fiber with a two-dimensional structure. The synthesis of beta-glucan microfibrils was directed in arrays by cortical microtubules at many loci on the membrane sheets. The microfibrils were mainly arranged along the microtubules, but the distribution of microfibrils was not always parallel to that of the microtubules. The rate of beta-glucan elongation as determined directly on the exoplasmic surface was 620 nm per min. When the assembly of microtubules was disrupted by treatment with propyzamide, the beta-glucans were not deposited in arrays but in masses. This finding shows that the arrayed cortical microtubules are not required for beta-glucan synthesis but are required for the formation of arranged microfibrils on the membrane sheet.

Journal Article↗