PubMed Health⌕ Search

Biomedical subjects

M Kabuto

Publications and source records attributed to M Kabuto.

At least 19 recordsLinked to original sources
PubMed1999

Direct interaction of lignin and lignin peroxidase from Phanerochaete chrysosporium.

Binding properties of lignin peroxidase (LiP) from the basidiomycete Phanerochaete chrysosporium against a synthetic lignin (dehydrogenated polymerizate, DHP) were studied with a resonant mirror biosensor. Among several ligninolytic enzymes, only LiP specifically binds to DHP. Kinetic analysis revealed that the binding was reversible, and that the dissociation equilibrium constant was 330 microM. The LiP-DHP interaction was controlled by the ionization group with a pKa of 5.3, strongly suggesting that a specific amino acid residue plays a role in lignin binding. A one-electron transfer from DHP to oxidized intermediates LiP compounds I and II (LiPI and LiPII) was characterized by using a stopped-flow technique, showing that binding interactions of DHP with LiPI and LiPII led to saturation kinetics. The dissociation equilibrium constants for LiPI-DHP and LiPII-DHP interactions were calculated to be 350 and 250 microM, and the first-order rate constants for electron transfer from DHP to LiPI and to LiPII were calculated to be 46 and 16 s-1, respectively. These kinetic and spectral studies strongly suggest that LiP is capable of oxidizing lignin directly at the protein surface by a long-range electron transfer process. A close look at the crystal structure suggested that LiP possesses His-239 as a possible lignin-binding site on the surface, which is linked to Asp-238. This Asp residue is hydrogen-bonded to the proximal His-176. This His-Asp...proximal-His motif would be a possible electron transfer route to oxidize polymeric lignin.

Amino Acid Sequence↗
PubMed1999

Alterations of calcium/calmodulin-dependent protein kinase II activity in ischaemia-induced neuronal death and neuronal protection against ischaemia in the gerbil hippocampus.

To clarify the relation between neuronal protection against ischaemia and calcium/calmodulin-dependent protein kinase II (CaM kinase II) activity, we investigated temporal alterations of the kinase activity in the hippocampus after transient forebrain ischaemia under neuroprotective conditions, employing the gerbil bilateral carotid artery occlusion model. The hippocampal CA1 neuronal density at 2 hours after 5 minutes of forebrain ischaemia was 214.7 +/- 25.8/mm (mean +/- S.D.), and did not differ from the control significantly; however, it decreased to 11.7 +/- 4.2/mm at 7 days after the ischaemia. The neuronal density at 7 days after the ischaemia was 185.1 +/- 18.5 under the hypothermic conditions, 128.7 +/- 19.6 with the brief ischaemic pretreatment, 65.0 +/- 13.4 with administration of MK-801, and 20.5 +/- 4.2 with the repetitive hyperthermic pretreatment, respectively. The Ca2+/calmodulin-dependent activity of CaM kinase II in the hippocampal cytosolic fraction was decreased to 47.5% of the control value at 2 hours after the ischaemia, when CA1 neuronal death was not observed. In contrast, the activity was 98.8% of the control under the hypothermic conditions, 91.4% with the brief ischaemic pretreatment, 71.2% with administration of MK-801, and 47.9% with the repetitive hyperthermic pretreatment, respectively. These results indicated that the preservation of the Ca2+/calmodulin-dependent activity of cytosolic CaM kinase II after ischaemia parallelled the neuroprotective effect in the gerbil hippocampus. Thus, it is suggested that the preservation of the activity may be involved in the mechanism of neuronal protection against ischaemia.

Animals↗
PubMed1999

Hemodynamic and metabolic changes following cerebral revascularization in patients with cerebral occlusive diseases.

Changes in cerebral hemodynamics and metabolism following cerebral revascularization were evaluated using positron emission tomography (PET). Ten patients who had received nonsurgical treatment for 3-6 months for minor completed stroke underwent superficial temporal artery to middle cerebral artery (STA-MCA) bypass surgery. All patients showed no extensive infarction on MR, and responsible vascular lesions were detected in the anterior circulation. A PET study of cerebral blood flow (CBF), oxygen extraction fraction (OEF), cerebral metabolic rate for oxygen (CMRO2), and cerebral metabolic rate for glucose (CMRGlu) measurements was performed before and 1.5 months after surgery using a steady state technique. Angiographically, anastomotic sites were patent in all patients. Seven patients showed neurological improvement after surgery and the others showed no improvement. The decreases in CBF, CMRO2 and CMRGlu recovered to some extent not only on the lesion side but also on the contralateral side after surgery. The increase in OEF values on the lesion side subsequently decreased after surgery. CMRO2 and CMRGlu showed parallel changes. It is concluded that the metabolic improvement afforded by the cerebral revascularization resulted in the neurological improvement, and that PET study is a powerful method for evaluating patients with cerebral occlusive diseases.

Aged↗
PubMed1999

Helicobacter pylori infection and atrophic gastritis in middle-aged Japanese residents of São Paulo and Lima.

BACKGROUND: Helicobacter pylori infection and atrophic gastritis (AG) are markedly more prevalent in Japan than in other industrialized countries, however, the reasons for such a high prevalence are not fully understood. To add to information on H. pylori infection and its association with AG, the authors studied Japanese living in less developed countries. METHODS: Cross-sectional surveys were conducted of randomly selected Japanese residents aged 40-59 years in São Paulo, Brazil and Lima, Peru. Serum IgG antibody to H. pylori and pepsinogen I (PGI) and II (PGII) were measured as markers of AG. RESULTS: The prevalence of H. pylori infection was similar in both populations, 77% (95% CI: 70-83) in São Paulo and 75% (95% CI: 65-82) in Lima, and was within the range of five populations in Japan from our previous study. However, the prevalence of AG, defined by PGI < 70 ng/ml and PGI/PGII < 3.0 was more prevalent among Japanese in São Paulo (39% [95% CI: 32-47]), than Japanese in Lima (18% [95% CI: 12-27]). This difference was not explained by sex, age, generation or H. pylori infection. CONCLUSIONS: Helicobacter pylori infection among Japanese in less developed countries was similar to Japanese in Japan, although prevalence of AG varied. Factors other than H. pylori infection are important in the development of AG among Japanese.

Adult↗
PubMed1998

Association of dehydroepiandrosterone sulfate with serum HDL-cholesterol concentrations in post-menopausal Japanese women.

OBJECTIVES: Positive association between serum dehydroepiandrosterone sulfate (DHEAS) and high-density lipoprotein (HDL) cholesterol has been observed in men but not women. We aimed to examine the cross-sectional relationships of DHEAS, estradiol (E2), and sex hormone-binding globulin (SHBG) to serum lipid concentrations in post-menopausal Japanese women. METHODS: A total of 56 post-menopausal Japanese women were derived from female residents in Takayama City in Japan. The information on body size, disease history, reproductive history, diet, and physical activity were obtained by a self-administered questionnaire. RESULTS: DHEAS was significantly and positively correlated with HDL-cholesterol after controlling for age and body mass index (BMI) (r = 0.28). There was no correlation between DHEAS and total-cholesterol (r = -0.02). E2 was not significantly correlated with total- and HDL-cholesterol and triglyceride. However, SHBG-unbound E2 was significantly positively correlated with HDL-cholesterol (r = 0.34) and negatively correlated with triglyceride (r = -0.27) after controlling for age and BMI. SHBG was negatively correlated with triglyceride, although the correlation was not statistically significant (r = -0.22). CONCLUSION: These data suggest favorable effect of DHEAS as well as E2 and SHBG on lipid profile in Japanese post-menopausal women.

Cholesterol, HDL↗
PubMed1998

Production of urokinase-type plasminogen activator (u-PA) and plasminogen activator inhibitor-1 (PAI-1) in human brain tumours.

We investigated the role of plasminogen activators (PAs) and their inhibitor (plasminogen activator inhibitor-1, PAI-1) in human brain tumours. The amounts of urokinase-type plasminogen activator (u-PA), tissue-type plasminogen activator (t-PA), and plasminogen activator inhibitor-1 (PAI-1), and the activity of u-PA and t-PA were determined by enzyme-linked immunosorbent assay (ELISA), and u-PA and PAI-1 were immunolocalized using monoclonal antibodies in human brain tumours and normal brain tissues. The tissues were surgically removed from 64 patients; normal brain tissue (5 cases), low-grade glioma (4 cases), high-grade glioma (17 cases), metastatic tumour (9 cases), meningioma (benign 12 cases, malignant 6 cases), acoustic schwannoma (11 cases). u-PA activity and u-PA and PAI-1 antigen levels were significantly elevated in malignant brain tumours (malignant meningiomas, high-grade gliomas, and metastatic tumours) and acoustic schwannomas but very low in benign meningiomas, low-grade gliomas and normal brain. There was no difference in t-PA antigen levels among normal and malignant tissues, however levels of t-PA activity were markedly decreased in metastastic tumours. All malignant brain tumour tissues showed positive immunostaining for u-PA and PAI-1, however, some tumour cells showed negative intensity while others showed strong intensity for these antibodies. This contrasts to the homogeneous staining pattern found in acoustic schwannoma. These findings indicate that malignancy in human brain tumours is associated with elevated levels of u-PA and PAI-1 and that an imbalance between these proteins in a micro-environment contributes (ascribes) to tumour cell invasion.

Adolescent↗
PubMed1998

Sensitization to hyperthermia by intracellular acidification of C6 glioma cells.

Hyperthermia has been introduced as a new modality of treatment for glioma. In these experiments, the cytotoxicity of hyperthermia in C6 glioma cells was enhanced by increasing the intracellular acidity with amiloride and/or 4,4'-diisothiocyanatostilbene-2,2' disulfonic acid (DIDS). Intracellular pH (pHi) is regulated mainly by Na+/H+ and HCO3-/Cl- antiports through the cell membrane, and amiloride acts on the former, DIDS on the latter to lower pHi. The cellular thermosensitivity to clinically achievable brain hyperthermia at 42 degrees C was enhanced by 0.5 mM amiloride (Na+/H+ antiport inhibitor). T0 values (T0 = the heating period required to reduce experimental survival rate by 1/e) at 42 degrees C without and with amiloride was 192 and 81 min, respectively. The addition of DIDS (HCO3-/Cl- antiport inhibitor) further enhanced. T0 value was 25 min. Fluorophotometric measurement of pHi was employed using the pH sensitive dye, bis(carboxyethyl)carboxyfluorescein, which is trapped in viable cells. The average pHi in control C6 glioma cells in pH 7.2 media was 7.21. In the untreated cells heated at 42 degrees C for 1 hour, the pHi was 7.12. The pHi of the cells heated in the presence of amiloride was decreased to 6.83. The pHi was further lowered to 6.67 by the treatment with amiloride in combination with DIDS for 2 hours. Hyperthermia with amiloride and DIDS may be a more effective treatment for malignant gliomas.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1998

Association of coffee, green tea, and caffeine intakes with serum concentrations of estradiol and sex hormone-binding globulin in premenopausal Japanese women.

Caffeine intake has been proposed to influence breast cancer risk. Its effect may be mediated by hormonal changes. The relationships between caffeine-containing beverages (coffee, green tea, black tea, oolong tea, and cola) and serum concentrations of estradiol and sex hormone-binding globulin were evaluated in 50 premenopausal Japanese women. Intakes of caffeine and caffeine-containing beverages were assessed by a semiquantitative food-frequency questionnaire. Blood samples were obtained from each woman on Days 11 and 22 of her menstrual cycle. High intakes of caffeinated coffee, green tea, and total caffeine were commonly correlated with increasing sex hormone-binding globulin on Days 11 and 22 of the cycle after controlling for potential confounders [Spearman correlation coefficients (r) ranged from 0.23 to 0.31]. Green tea but not caffeinated coffee intake was inversely correlated with estradiol on Day 11 of the cycle (r = -0.32, p = 0.04). Although the effect of caffeine cannot be distinguished from effects of coffee and green tea, consumption of caffeine-containing beverages appeared to favorably alter hormone levels associated with the risk of developing breast cancer.

Adult↗
PubMed1998

Prevalence of use of medically prescribed hypnotics among adult Japanese women in urban residential areas.

Based on a population survey on insomnia among 3600 adult Japanese women living in urban areas, the prevalence of use of medically prescribed hypnotics is determined. The prevalence of use of medically prescribed hypnotics increases with an increase in age (<1.0% for those aged 49 or younger, while 14.3% for those aged 70 or older), in agreement with the results reported in many Western nations. The current sleep disturbance is mild in nearly half of these hypnotics users. More than one-third of the hypnotic users are receiving health care not for sleep problems but for depression, anxiety, or other reasons. More than one-third of the hypnotic users are found to be receiving hypnotics from non-psychiatrists. The percentage of this group is particularly high among those aged 60 or over, probably reflecting the fact that they are often consulting physicians for physical reasons. On the other hand, more than 80% of insomniacs are suggested to be untreated. Future public health research should focus on the quality of life and health care behaviors of untreated insomniacs and hypnotic users, especially among the elderly people, in order to assess the need for primary health care to prevent accidents, mortality, and psychiatric disorders related to sleep problems.

Adult↗
PubMed1998

Changes in messenger ribonucleic acid species in gerbil brain perturbation.

The differential display technique was applied to observe the molecular dynamism of messenger ribonucleic acid (mRNA) in this study. Using this technique, the changes in mRNAs in brain perturbation such as ischemia was observed to understand the molecular base of the reaction. The transient cerebral ischemia was induced by clipping both common carotid arteries for 5 minutes in Mongolian gerbils. The total RNA was extracted from the hippocampal tissue samples before ischemia, 6 hours and 2 days after ischemia. The mRNAs were reverse transcribed and subsequently amplified by polymerase chain reaction (PCR). PCR products were displayed by autoradiography as ladders on a denaturing polyacrylamide gel. According to the autoradiography, mRNAs were divided into three patterns: 1) mRNAs obtained from the control decreased at 6 hours after 5-minute ischemia and disappeared at 2 days completely; 2) decreased mRNAs at 6 hours after ischemia recovered at 2 days; and 3) new mRNAs appeared after cerebral ischemia. Located bands of interest on a gel were cut out and reamplification of complementary deoxyribonucleic acid was performed. The pGEM-T Vector System was used for subcloning of the amplified PCR products. The differential display technique is the powerful method for detecting genes that are unique to ischemic processes and reactions.

Animals↗
PubMed1998

Effects of passive smoking on serum levels of carotenoids and alpha-tocopherol.

To evaluate the effects of passive smoking identified by urine cotinine on serum carotenoids and alpha-tocopherol, we categorized 124 residents in a rural city of Japan into 4 groups by their urine cotinine/creatinine (Cot/Cr) ratio (u.d. (undetectable); low (0-50 ng/mg); moderate (50-120 ng/mg); high (> 120 ng/mg)) and compared the serum carotenoids and alpha-tocopherol levels among these groups. We identified passive smoking by low Cot/Cr ratio level. After controlling on related factors, men with low Cot/Cr ratio showed significantly lower serum zeaxanthin/lutein levels than men with u.d. Cot/Cr ratio. The difference was still marginally significant after excluding self-reported current smokers from the low Cot/Cr group. It is suggested that low level exposure to tobacco smoke, which has been reported to be equivalent to that for passive smokers, could be associated with decreased serum zeaxanthin/lutein levels in men.

Aged↗
PubMed1998

Long commuting time, extensive overtime, and sympathodominant state assessed in terms of short-term heart rate variability among male white-collar workers in the Tokyo megalopolis.

To investigate the possible effects of long commuting time and extensive overtime on daytime cardiac autonomic activity, the short-term heart rate variability (HRV) both at supine rest and at standing rest of 223 male white-collar workers in the Tokyo Megalopolis was examined. Workers with a one-way commute of 90 min or more exhibited decreased vagal activity at supine rest and increased sympathetic activity regardless of posture, and those doing overtime of 60 h/month or more exhibited decreased vagal activity and increased sympathetic activity at standing rest. These findings suggest that chronic stress or fatigue resulting from long commuting time or extensive overtime caused these individuals to be in a sympathodominant state. Although these shifts in autonomic activities are not direct indicators of disease, it can be hypothesized that they can induce cardiovascular abnormalities or dysfunctions related to the onset of heart disease. Assessment of the daily and weekly variations in HRV as a function of daily life activities (such as working, commuting, sleeping, and exercising) among workers in Asia-Pacific urban areas might be one way of studying the possible effects of long commuting time, and extensive overtime, on health.

Adult↗
PubMed1998

Self-reported sleep quality, job stress, and daytime autonomic activities assessed in terms of short-term heart rate variability among male white-collar workers.

To investigate the relationships among the amount of job stressors, self-reported sleep quality, and daytime autonomic activities, a questionnaire survey was conducted for 223 healthy male white-collar workers, and their short-term heart rate variability (HRV) was also examined. Half of the subjects complained of nightly poor sleep quality. Self-reported poor sleep quality was associated with a qualitative aspect of job stressors characterized by high amounts of "job difficulty", less amounts of "achievement in job", and less amounts of "support by colleagues", and also with high amounts of personal distress and difficulty in changing their mood. Those who complained of poor sleep quality exhibited sympathetic predominance and reduced heartbeat intervals at standing rest, although job stressors was not correlated to HRV. These results suggest that their job stress disrupts nightly sleep, and also that their insufficient sleep at night causes daytime sympathetic predominance. However, the amount of job stressors was not directly associated with HRV. Further studies should focus on the relationships among chronic job stress, the satisfaction of sleep demands, and the daily and long-term variation in cardiac autonomic activities.

Adult↗
PubMed1998

Long-term evaluation of reconstruction of the sellar floor with a silicone plate in transsphenoidal surgery.

OBJECT: The authors have used a silicone plate for reconstruction of the sellar floor during rhinoseptoplastic transsphenoidal surgery because it has greater elasticity and is easier to carve than nasal septal cartilage and sphenoid sinus bone. This study was designed to evaluate the usefulness of this technique based on the authors' experience during the past 7.6 years. METHODS: A silicone plate was used to reconstruct the sellar floor in 69 consecutive patients with sellar tumors that included 60 pituitary adenomas and nine Rathke's cleft cysts. The patients ranged in age from 16 to 82 years (mean 52 years). The postoperative position of the silicone plate could be clearly identified on sagittal or coronal magnetic resonance (MR) imaging as a very low intensity plate (void signal). No displacement or migration of the implanted silicone plate was observed on follow-up MR imaging in any patient. Infections of the lesion such as a pituitary abscess were not observed clinically or radiologically in any patient. Of the 16 patients with intraoperative cerebrospinal fluid (CSF) leakage, only one patient who had a ghost sella developed postoperative CSF rhinorrhea. In all seven patients who underwent repeated surgery for residual or recurrent tumor, the silicone plate that had been placed at the initial procedure was covered with a relatively thin fibrous capsule and the plate was well preserved. The silicone plate was easily removed at reoperation and was useful for detection of the sellar floor window made previously. CONCLUSIONS: These results indicate that a silicone plate can be useful for reconstruction of the sellar floor in rhinoseptoplastic transsphenoidal surgery.

Adenoma↗
PubMed1998

Interleukin-1 receptor antagonist inhibits transient increase of plasma corticosterone in the initial phase of trimethyltin-induced hippocampal necrosis.

The temporal increase of plasma corticosterone (CORT) levels at 3 or 4 days after a single oral administration of trimethyltin (TMT) was suppressed by intracerebroventricular administration of the interleukin-1 receptor antagonist (IL-1ra). On the other hand, glutamate receptor antagonist (MK801) did not affect the TMT-induced CORT level increase. These results indicate that this transient activation of the hypothalamo-pituitary-adrenocortical axis in TMT-treated rats may be in part attributable to the neuroendocrine effects of IL-1 produced by microglia.

Administration, Oral↗
PubMed1998

[Intraoperative CT imaging system using a mobile CT scanner gantry mounted on floor-embedded rails for neurosurgery].

Many neurosurgeons prefer to use intraoperative computed tomographic (CT) scanning, when possible, to check whether there is residual lesion or unexpected bleeding. We report a practical intraoperative CT imaging system using a high-speed CT scanner installed in the operating room along with a digitally controlled neurosurgical operating table. We designed a rail-track system to mobilize the CT gantry. The gantry is fixed onto a motorized carrier that can be moved smoothly on a rail-track embedded in the floor and with a maximum reach of 2.85 m from the room's wall to the operating table. The longitudinal motion of the operating table is easily adjusted by a foot switch from manual control to automatic control directly from the CT scanner's computer like an ordinary CT scanner bed in increments of 2, 5 or 10 mm during CT scanning. Either a carbon-made radiolucent head frame or carbon-made head plate is used as a headrest. Using this CT scanner system, pre- and intraoperative CT scannings were performed on 46 patients with brain tumors, cervical lesions or other intracranial lesions. We could operate on the patient with enough working space between the mobile CT gantry and the operating table for microneurosurgery. We could obtain intraoperative CT imaging of a patient on the operating table while the surgical wound remained open, the surgical drapes kept in place, and the surgical position unchanged, saving time in intraoperative CT scanning and preparation for further surgery when needed. This intraoperative CT imaging system installed in the operating room should be useful for neurosurgery.

Brain↗
PubMed1997

Transient cerebral ischaemia in Mongolian gerbils pre-exposed to hypoxia.

The objective of this study was to clarify whether pre-exposure to hypoxia influences neuronal death following transient cerebral ischaemia. Twenty gerbils were exposed to 10% oxygen in a chamber for 3 weeks. The other control gerbils (n = 20) were fed in normoxia for 3 weeks. Both carotid arteries in the neck were occluded with aneurysm clips for 5 minutes under halothane anaesthesia in 30 gerbils, recirculated and then fed in normoxia. Five animals in both groups were sacrificed before, and 2, 4, and 7 days after surgery. The animals were fixed with 4% paraformaldehyde and histological study was performed. Immunohistochemical study was also done with antibodies against basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF). The neuronal death in the hippocampus was more severe in the hypoxic group. Expression of both bFGF and VEGF was obvious in the cingulate cortex, corpus callosum and internal capsule before clipping in the hypoxic group, but not observed in the normoxic group before clipping. We observed the expression of both bFGF and VEGF widely in the brain at 2 and 4 days after recirculation in both groups. The expression in the hypoxic group was much more prominent than that in the normoxic group. These expressions were not observed at 7 days in both groups. Pre-exposure to hypoxia followed by transient cerebral ischaemia accelerated neuronal death in the hippocampus, and induced the more obvious expression of both VEGF and bFGF compared with those in the normoxic group.

Animals↗