Biomedical subjects

K Sakai

Publications and source records attributed to K Sakai.

At least 109 records · Page 6Linked to original sources

PubMed2001

Supratentorial astrocytomas and oligodendrogliomas treated in the MRI era.

BACKGROUND: There is at present no consensus on the policy for the treatment of patients with low-grade gliomas (LGGs). METHODS: This report is a retrospective multi-institutional study of 100 patients (ages 16-65 years) with astrocytoma (grade II), oligodendroglioma, anaplastic oligodendroglioma and anaplastic oligoastrocytoma of the supratentorial areas which were treated with surgery and postoperative radiotherapy at five university hospitals in northern Japan between 1990 and 1997 when MRI was routinely used to determine the target volume. Most patients were irradiated with 50-60 Gy. The target volume usually covered the areas with T2 prolongation of MRI with a margin of 2 cm. RESULTS: The disease-specific 5-year survival rate was 87.4% for patients with oligodendroglioma and 75.3% for patients with astrocytoma. Survival for patients with astrocytoma in the MRI era appears to be improved compared with historical controls in the literature. Patients with astrocytoma aged 40 years and under had a significantly better disease-specific survival rate than those over 40 years (P < 0.05) and patients with oligodendroglioma and oligoastrocytoma showed a similar tendency. Patients with astrocytoma who had over 50% of their tumor removed had a significantly better survival rate than those who had less than 50% removed (P < 0.05). Chemotherapy appeared to improve the disease-specific survival rate of patients with oligodendroglioma but not that of patients with astrocytoma. CONCLUSION: Oligodendroglioma has a more protracted course of disease progression than astrocytoma. This particular feature and the sensitivity of LGGs to chemotherapy as well as their relevant prognostic factors, such as age, histopathology and amount of tumor removal, should be taken into account before any decision on treatment methods for LGGs is made.

Adult↗

PubMed2001

Dietary fructooligosaccharides modify intestinal bioavailability of a single dose of genistein and daidzein and affect their urinary excretion and kinetics in blood of rats.

The influence of dietary fructooligosaccharides (FOS) on bioavailability of genistein and daidzein in rats was estimated by measuring their concentrations in plasma collected from three different veins and in urine after a single intragastric administration of isoflavone conjugates. Sprague-Dawley male rats (6 wk old, n = 22) were fed a purified control (AIN-93G) diet or a FOS diet (AIN-93G + 5% FOS) for 7 d. A single dose of soy isoflavone conjugates, i.e., 8.5 mg as genistein and 33 mg as daidzein/kg body, was administered via a stomach tube at d 5. Blood samples were collected after administration via catheters in the portal and central veins and by puncture of the tail vein. The isoflavones in plasma and urine were analyzed by time-resolved fluoroimmunoassay. The genistein concentration in the portal blood increased rapidly, reaching a peak of 3.5 micromol/L in both groups at 1 h after administration. The concentrations in the central and tail venous blood were approximately half of those in the portal blood. In the FOS-fed group, both genistein and daidzein remained detectable at 24 and 48 h in the tail venous plasma. The urinary excretion of both isoflavones in the 24- to 48-h period after administration was significantly higher in the FOS-fed group than in the control group. The difference between the portal and central veins indicated hepatic uptake, probably leading to conjugation of aglycones and excretion into bile. FOS modified the absorption and enterohepatic recirculation of isoflavones.

Animals↗

PubMed2001

Electroacupuncture stimulation suppresses the increase in alcohol-drinking behavior in restricted rats.

BACKGROUND: Although a number of studies on traditional eastern or Chinese medicine, such as acupuncture, moxibustion, and herbal drugs, have been reported, few reports describe electroacupuncture (EAC) effects on drug- and alcohol-seeking behaviors in animal models. The purpose of the present study was to investigate the effect of EAC on changes in alcohol-drinking behavior in rats challenged with restriction and immobilization stress. MATERIAL AND METHODS: Male Sprague Dawley rats (260-280 g) were tightly hung and immobilized in restriction models for 10 min. These immobilization stresses were performed twice a week for 1 week and for 3 consecutive weeks for the short- and long-restricted stress groups, respectively. EAC was applied for 10 min to the hindlimb point, Tsu-San-Li (ST 36), and the lumbar point, Shen-Shu (BL 23). These points are used to treat mental and psychosomatic disorders and are known clinically to produce a sedation effect. Time-access alcohol-drinking behavior was determined at 24 hr after the termination of EAC. Finally, brain dopamine (DA) levels were assayed in the two groups. A sham-control group underwent only restricted stress without EAC. RESULTS: Time-access alcohol-drinking behavior increased significantly in the long-restricted group compared with the short-restricted group and controls. EAC applied to the ST 36 (Tsu-San-Li) point suppressed the increased alcohol-drinking behavior in restricted rats. However, EAC applied to the Shen-Shu (BL 23) point was not effective, because alcohol-drinking behavior was significantly increased in long-restricted rats compared with short-restricted rats. Striatal DA levels of restricted rats with EAC stimulated at Tsu-San-Li were increased significantly compared with the rats with EAC applied to the Shen-Shu point. CONCLUSION: These findings suggest that EAC applied at ST 36 (Tsu-San-Li) was more effective for reducing the increased alcohol-drinking behavior in restricted rats, and they showed that a point specific in EAC procedure was associated with an increase of striatal DA levels. These findings provide new information for understanding alcohol-drinking behavior and for treating human alcoholics.

Alcohol Drinking↗

PubMed2001

Apical leakage of obturated canals prepared by Er:YAG laser.

The present study evaluates the degree of apical leakage in vitro after root canal preparation using Er:YAG laser irradiation followed by obturation. Twenty-four single-rooted teeth were divided into 2 groups of 12. One group served as a control and these root canals were conventionally prepared up to a #50K file. The other group was prepared by Er:YAG laser irradiation at parameters of 2 Hz and 170 to 230 mJ/pulse. After obturation the teeth were immersed in a vacuum flask containing 0.6% rhodamine for 48 h, longitudinally bisected, and observed by stereoscopy and scanning electron microscopy. The degree of apical leakage from an apical stop was measured and statistical analysis was performed. The degree of apical leakage from the teeth prepared by laser was not significantly less than that from control teeth (p > 0.01). Morphological findings showed that contact between the root canal walls and obturated materials was hermetic in both groups, but canal walls prepared by laser were rough and irregular. These results show that root canal preparation by laser does not affect apical leakage after obturation compared with leakage in canals prepared using the conventional method.

Dental Leakage↗

PubMed2001

Clinical significance of urinary interleukin-6 in children with reflux nephropathy.

PURPOSE: We determined urinary interleukin-6 (IL-6) in children with reflux nephropathy to evaluate the clinical significance of this cytokine in the progression of renal injury. MATERIALS AND METHODS: Enrolled in this study were 34 boys and 32 girls in whom 99mtechnetium dimercapto-succinic acid renal scan showed renal scarring. Vesicoureteral reflux had been corrected surgically at least 3 years before study entry. Urinary IL-6 was determined by enzyme-linked immunosorbent assay using spot urine samples. Simultaneously we measured serum creatinine, beta2-microglobulin, alpha1-microglobulin, urinary alpha1-microglobulin and albumin. In addition, IL-6 expression was assessed by immunohistochemical study in the scarred kidneys of 3 boys and 1 girl who underwent nephrectomy due to severe reflux nephropathy with little function on renal scan. RESULTS: Urinary IL-6 was significantly higher in children with severe bilateral renal scarring than in those with mild scarring and normal controls. Urinary IL-6 correlated significantly with serum alpha1-microglobulin (Spearman test p <0. 03), beta2-microglobulin (p <0.003), creatinine (p <0.02) and urinary albumin (p <0.0001). Histological evaluation revealed that IL-6 was predominantly expressed in the tubules in and adjacent to fibrotic areas. CONCLUSIONS: Our observations indicate that tubular IL-6 may be involved in the pathogenesis of tubulointerstitial injury in reflux nephropathy and urinary IL-6 may be a useful tool for monitoring the progression of reflux nephropathy.

Adolescent↗

PubMed2001

Adenovirus-mediated gene transfer into the NTS in conscious rats. A new approach to examining the central control of cardiovascular regulation.

The nucleus tractus solitarii (NTS) is an important site for the regulation of sympathetic nerve activity. It receives the signals through afferent fibers from arterial baroreceptors, chemoreceptors, cardiopulmonary receptors, and other visceral receptors. Many studies have examined the role of nitric oxide (NO) in the NTS in cardiovascular regulation. However, most of these studies were conducted in an acute state with anesthesia. We have developed a novel technique of endothelial nitric oxide synthase (eNOS) gene transfer into the NTS in vivo. Adenovirus vectors encoding either the beta-galactosidase gene (Ad beta gal) or the endothelial nitric oxide synthase gene (AdeNOS) gene were transfected into the NTS. In the Ad beta gal-treated rats, the local expression of beta-galactosidase was confirmed by X-Gal staining, and beta-galactosidase activity was quantified using a colorimetric assay. In the AdeNOS-treated rats, the local expression of eNOS protein was confirmed by immunohistochemistry, and eNOS production was measured by in vivo microdialysis. Blood pressure and heart rate were monitored by a radiotelemetry system in a conscious state. The expression of each gene was observed from day 5 to day 10 after the gene transfer. In the AdeNOS-treated rats, blood pressure and heart rate significantly decreased from day 5 to day 10, and then thereafter gradually recovered over time. Our method may be useful in examining the local effect of a particular substance produced by a specific gene in the brain on cardiovascular function.

Adenoviridae↗

PubMed2001

Glutamate release via NO production evoked by NMDA in the NTS enhances hypotension and bradycardia in vivo.

Nitric oxide (NO) in the nucleus tractus solitarii (NTS) plays an important role in regulating sympathetic nerve activity. The aims of this study were to determine whether the activation of N-methyl-D-aspartate (NMDA) receptors in the NTS facilitates the release of L-glutamate (Glu) via NO production, and, if so, to determine whether this mechanism is involved in the depressor and bradycardic responses evoked by NMDA. We measured the production of NO in the NTS as NO2- and NO3- (NO(x)) or Glu levels by in vivo microdialysis before, during, and after infusion of NMDA in anesthetized rats. We also examined effects of N(omega)-nitro-L-arginine methyl ester (L-NAME) on the changes in these levels. NMDA elicited depressor and bradycardic responses and increased the levels of NO(x) and Glu. L-NAME abolished the increases in the levels of NO(x) and Glu and attenuated cardiovascular responses evoked by NMDA. These results suggest that NMDA receptor activation in the NTS induces Glu release through NO synthesis and that Glu released via NO enhances depressor and bradycardic responses.

Animals↗

PubMed2001

Noise-enhanced heart rate and sympathetic nerve responses to oscillatory lower body negative pressure in humans.

By injecting noise into the carotid sinus baroreceptors, we previously showed that heart rate (HR) responses to weak oscillatory tilt were enhanced via a mechanism known as "stochastic resonance." It remains unclear, however, whether the same responses would be observed when using oscillatory lower body negative pressure (LBNP), which would unload the cardiopulmonary baroreceptors with physically negligible effects on the arterial system. Also, the vasomotor sympathetic activity directly controlling peripheral resistance against hypotensive stimuli was not observed. We therefore investigated the effects of weak (0 to approximately -10 mmHg) oscillatory (0.03 Hz) LBNP on HR and muscle sympathetic nerve activity (MSNA) while adding incremental noise to the carotid sinus baroreceptors via a pneumatic neck chamber. The signal-to-noise ratio of HR, cardiac interbeat interval, and total MSNA were all significantly improved by increasing noise intensity, while there was no significant change in the arterial blood pressure in synchronized with the oscillatory LBNP. We conclude that the stochastic resonance, affecting both HR and MSNA, results from the interaction of noise with the signal in the brain stem, where the neuronal inputs from the arterial and cardiopulmonary baroreceptors first come together in the nucleus tractus solitarius. Also, these results indicate that the noise could induce functional improvement in human blood pressure regulatory system in overcoming given hypotensive stimuli.

Adult↗

PubMed2001

Prolonged antigen exposure ameliorates airway inflammation but not remodeling in a mouse model of bronchial asthma.

BACKGROUND: In naive rodents, repeated exposure to aerosolized antigen induces suppression of the Th2 response to the antigen. We hypothesized that more prolonged exposure of established asthma model to antigen aerosols may downregulate asthmatic phenotype. METHODS: After establishing an ovalbumin (OVA)-induced asthma model, mice were further exposed to OVA (prolonged exposure group) or phosphate-buffered saline (positive controls) 3 days per week for 6 weeks. During week 7, the mice of both groups were finally challenged with OVA. RESULTS: Prolonged OVA exposure resulted in marked suppression of serum OVA-specific immunoglobulin E (IgE) antibody levels, eosinophilia of the airway, and airway hyperresponsiveness (AHR). However, airway remodeling characterized by goblet cell hyperplasia and airway fibrosis was observed to the same degree in both groups. These effects were accompanied by diminished production of Th2 cytokines such as interleukin-4 (IL-4), IL-5 and IL-13 in bronchoalveolar lavage fluid (BALF) and cultured supernatant of splenocytes. Furthermore, prolonged exposure markedly increased IL-12 levels in BALF. CONCLUSIONS: Prolonged antigen exposure has inhibitory effects on eosinophilic inflammation, AHR and IgE response to antigen, but not on airway remodeling, presumably via inhibition of Th2 cytokines and increased IL-12 production in the lungs.

Animals↗

PubMed2001

Fractal dimension analysis of static stabilometry in Parkinson's disease and spinocerebellar ataxia.

The static stabilometry patterns associated with Parkinson's disease (PD, n = 15) and spinocerebellar ataxia (SCA, n = 15) were compared with those of normal control (n = 15) by measuring the fractal dimensions. Fractal dimensions were estimated using the modified pixel dilation (mPD) method. The fractal dimensions with closed eyes showed a significant correlation with Environmental area for SCA group (p < 0.05). The fractal dimension for SCA group was significantly higher with closed eyes than that with open eyes (p < 0.05). The fractal dimension with closed eyes was significantly higher in PD and SCA groups than that in normal group (p < 0.05). The fractal dimension with closed eyes was higher when the clinical stage was more severe with PD and SCA group while Environmental and Longitude/Environmental areas were not. These findings suggest that the fractal dimension is more sensitive than traditional stabilometric analysis in an evaluation of postural instability in PD and SCA.

Aged↗

PubMed2001

Different expression of glycogen synthase kinase-3beta between young and old rat brains after transient middle cerebral artery occlusion.

Ischemia is a common stress to human brain and is difficult to cure in older individuals. To examine the differences of the response to cerebral ischemia between young and old rat brains, distributions of glycogen synthase kinase-3beta (GSK3beta) and tau proteins were analyzed after 90 min of transient middle cerebral artery occlusion (MCAO) in young (10-11 weeks) and old (15 months) rats by immunohistochemical analyses. At 4 h of reperfusion, strong cytoplasmic and nuclear immunoreactivity for GSK3beta was induced in neurons of lamina I, II, V and VI of the cerebral cortex and dorsal caudate in young brains, while the induction was not observed in lamina I and II of old cerebral cortex. The staining in lamina V and VI and dorsal caudate then gradually decreased until seven days of reperfusion in both animal groups. The staining of tau protein and terminal deoxynucleotidyl transferase-mediated dUTP-biotin in situ nick end labeling (TUNEL) did not show any positive signals in the control brain, but showed positive signals after ischemia with a peak at 24 h and 3 days, respectively. No significant difference was observed in the temporal and spatial patterns of tau and TUNEL stainings between these two groups. These data suggest that GSK3beta may have a role in ischemic neuronal cell death, and that the different spatial expression of GSK3beta between young and old rat brains may partly explain the vulnerability of older neurons after ischemia.

Aging↗

PubMed2001

Serial MRI findings in patient with chronic cryptococcus meningo-encephalitis.

We describe the serial changes of magnetic resonance imaging (MRI) in a patient with chronic cryptococcus meningo-encephalitis. In the subacute phase, MRI revealed a focal lesion with hyperintensity on T2-weighted image (WI) in the left thalamus. At 11 months after the onset, MRI showed a focal lesion with hyperintensity on T2-WI in the right pons that was enhanced with gadolinium (Gd). At 13 months after the onset, the lesion in the left thalamus became rim enhanced with Gd. After antifungal therapy (amphotericin B and 5-flucytosine), the rim enhancement in the left thalamus and the high signal intensity area in the right pons decreased. Cryptococcoma should be in the differential from other ring enhancing lesions.

Chronic Disease↗

PubMed2001

Th1/Th2 balance alteration in the clinical course of a patient with acute viral myocarditis.

Cytokines have an important role in the pathogenesis and pathophysiology of myocarditis. In this study, subsets of peripheral helper T lymphocytes (Th) in a patient with acute viral myocarditis were analyzed by 3-color flow cytometry. During the clinical course of myocarditis, the Th1/Th2 ratio of peripheral lymphocytes changed. Th1 was dominant in the acute inflammatory phase during which levels of creatine kinase (CK) increased (day 6), then Th2 levels overtook those of Th1 in the recovery phase during which levels of CK decreased (day 13 and 20). At the time of discharge (day 35), Th1 and Th2 had normalized. Thus, it was speculated that the induction of lymphocytic myocarditis was associated with Th1 dominant status, and recovery was related to Th2 polarity. Th subset imbalances may play an important role in the pathogenesis of acute viral myocarditis and these analyses may be useful for understanding the disease activity of myocarditis.

Adult↗

PubMed2001

Use of nonionic surfactants for effective supply of phosphatidic acid in serum-free culture of Chinese hamster ovary cells.

We have previously shown [Sakai et al., J. Biosci. Bioeng., 88, 306-309 (1999)] that exogenously supplied phosphatidic acid (PA) and lysophosphatidic acid (LPA) promoted the growth of Chinese hamster ovary (CHO) cells in serum-free culture. However, the direct addition of high concentrations of these phospholipids alone to the culture medium resulted in the formation of precipitates. We therefore examined the use of two nonionic surfactants, Tween 80 and Pluronic F-68, as a means of supplying PA more effectively to CHO cells in a serum-free culture. A clear dispersion of PA from egg yolk lecithin that could be successfully sterile-filtered was obtained by using Tween 80 or Pluronic F-68. When PA prepared with either of the surfactants was added to serum-free media, precipitation was noticeably reduced. Furthermore, the growth-promoting activity of PA was considerably enhanced by the presence of the surfactants. Since Tween 80 and Pluronic F-68 themselves possessed no growth-stimulating property, it was suggested that the enhanced growth-promoting activity results from the improved availability of PA to the cells. The use of Tween 80 with PA analogues having saturated acyl chains also accelerated cell growth, whereas these PAs showed little growth-promoting activity, due to their poor water-solubility, when added alone.

Journal Article↗

PubMed2001

Isolation of a thermophilic poly-L-lactide degrading bacterium from compost and its enzymatic characterization.

Thermophilic poly-L-lactide-degrading bacteria were isolated from a garbage fermentor. One of the isolates, strain PL21, was identified as Bacillus smithii based on its physiological properties, sugar assimilation pattern, and partial 16S rDNA sequence. The degradation activity of poly-L-lactide exibited by the culture fluid was parallel to the esterase activity, and the purified enzyme was active against various fatty acid esters and poly-L-lactide, at 60 degrees C and pH 5.

Journal Article↗

PubMed2001

Production of beta-thujaplicin in Cupressus lusitanica suspension cultures fed with organic acids and monoterpenes.

Effects of some organic acids and monoterpenes on production of beta-thujaplicin were studied in Cupressus lusitanica suspension cultures. The fungal elicitor-induced biosynthesis of beta-thujaplicin was promoted by the feedings of malate, pyruvate, fumarate, succinate, and acetate. These results suggest some relationships between acetate/pyruvate metabolism and beta-thujaplicin biosynthesis, or between tricarboxylic acid cycle and beta-thujaplicin biosynthesis. Feedings of C. lusitanica suspension cultures with some monoterpenes inhibited elicitor-triggered beta-thujaplicin biosynthesis, but 2-carene and terpinyl acetate feedings significantly improved the beta-thujaplicin production of C. lusitanica suspension cultures. These results indicate a possible involvement of terpinyl acetate and 2-carene in beta-thujaplicin biosynthesis, as well as potential uses of these monoterpenes in large-scale beta-thujaplicin production.

Acids↗

PubMed2001

Effect of dietary short-chain fructooligosaccharides on the cecal microflora in gastrectomized rats.

Total gastric resection is known to lead to changes in the microflora in the whole gastrointestinal tract. Dietary short-chain fructooligosaccharides (Sc-FOS) have been shown to also induce a change in the microflora in the large bowel by promoting an increase in the numbers of Bifidobacterium and Lactobacillus which have beneficial effects on the host. In the present study, 4-week-old male Sprague-Dawley rats received total gastrectomy or laparotomy, and each of these surgically treated groups was randomly divided into two experimental diet groups and given a 7.5% Sc-FOS diet or control diet. Enumeration and identification of the cecal bacteria was performed by using selective and non-selective media. In the gastrectomized rats, the total bacterial count, and the counts of Bacteroidaceae and Enterobacteriaceae were higher than those in the sham-operated rats. Sc-FOS promoted an increase in the numbers of Bifidobacterium and Lactobacillus, In the rats fed on the Sc-FOS diet, the predominant type of bacteria was Lactobacillus and in the rats fed on the control diet, it was Bacteroidaceae irrespective of gastrectomy. We confirmed that both gastrectomy and dietary Sc-FOS changed the composition of cecal microflora in the rats. Dietary Sc-FOS in the gastrectomized rats increased the proportions of Lactobacillus relative to other types of bacteria to levels similar to those seen in healthy normal rats, and decreased the proportion of Bacteroidaceae.

Animals↗

PubMed2001

Rheumatoid factor positive hypertrophic cranial pachymeningitis in association with hypopituitarism and multiple cranial nerve palsies.

This is the first report of a patient presenting with rheumatoid factor (RF) positive hypertrophic cranial pachymeningitis (HCP) in association with hypopituitarism and multiple cranial nerve palsies. Our patient developed palsies of the left II and III, bilateral VI and VII, and right IX, X, and XII cranial nerves. A stimulation test showed hypopituitarism due to hypothalamic failure. The patient was seropositive for RF but had no multiple joint pain or deformities. Magnetic resonance imaging (MRI) showed thickened dura of the sellar and parasellar region, hypothalamus, bilateral cavernous sinuses and the tentorium all of which were enhanced by gadolinium (Gd). Treatment with prednisone improved clinical symptoms and MRI findings concomitant with reduction of RF titer. Although the exact mechanism of HCP has not been clearly elucidated, the present case suggests an autoimmune mechanism associated with RF.

Aged↗