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K Shima

Publications and source records attributed to K Shima.

At least 55 records · Page 3Linked to original sources
PubMed2001

[Prediction of the need for mechanical ventilation after transsternal thymectomy in patients with myasthenia gravis].

Between June 1992 and May 2000, transsternal extended thymectomy was performed for 70 patients with myasthenia gravis in our hospital. We were able to evaluate 64 of them in terms of prediction of the need for postoperative mechanical ventilation using the score systems reported by Leventhal et al., Kimura et al. and the criteria of Adachi et al.. For these systems, the rates of agreement between predictions and results were 85.9%, 82.8%, and 64.1%, respectively. The two former systems had some false negative cases (i.e., they predicted that ventilation would not be needed when in fact it was), but the last one gave no false negatives. We recommend Adachi's criteria for clinical safety. In our cases the patients whose value of %VC multiplied by FEV1.0% was less than 7,000 (Adachi's criterion is less in 8,300), especially, needed careful management with regard to respiratory crisis.

Adolescent↗
PubMed2000

Genetic evidence for obesity loci involved in the regulation of body fat distribution in obese type 2 diabetes rat, OLETF.

The Otsuka Long-Evans Tokushima Fatty (OLETF) rat is an animal model for obese type 2 diabetes in human. Obesity is essential for the onset of type 2 diabetes in this rat. Our present investigation was designed to identify quantitative trait loci (QTLs) contributing to obesity by performing a whole-genome search using 214 F(2) intercross progeny between OLETF and F344 rats. We have identified six QTLs responsible for adiposity indices of fat pads on rat chromosomes 2 (Obs1 for mesenteric fat), 4 (Obs2 for retroperitoneal fat), 8 (Obs3 for mesenteric fat), 9 (Obs4 for retroperitoneal fat), and 14 (Obs5 and Obs6 for retroperitoneal fat), demonstrating that the adiposity indices of individual fat pads were under the control of different genes. As expected, the OLETF allele corresponds to increased adiposity indices for all QTLs, except for Obs3, in which the F344 allele leads to an increase in the index.

Adipose Tissue↗
PubMed2000

Response of leptin mRNA to 24-h food deprivation and refeeding is influenced by age in rats.

To obtain an insight into the influence of aging on leptin gene expression, the responses of leptin mRNA in retroperitoneal and epididymal adipose tissues and plasma leptin concentrations to 24-h food deprivation and refeeding were examined in 2-, 10- and 24-month-old normal rats. The basal level of leptin gene expression in retroperitoneal adipose tissue was significantly higher in 10- and 24-month-old rats than that in 2-month-old rats, while the level in epididymal adipose tissue was highest in 10-month-old rats for all three age groups. The basal concentrations of plasma leptin was significantly higher in 10- and 24-month-old rats than those in 2-month-old rats. The 24-h food deprivation was followed by a significant reduction in leptin mRNA expression in both retorperitoneal and epididymal adipose tissues for all three age groups. The leptin gene expression was restored to control levels 24 h following refeeding in the 2- and 10-month-old rats, but failed to be restored in the 24-month-old rats. In addition, the time course of recovery for leptin mRNA expression by refeeding to the control levels differed between the retroperitoneal and the epididymal adipose tissue in 2- and 10-month-old rats. The concentrations of plasma leptin 24 h following refeeding were compatible with the leptin mRNA levels in adipose tissues in three age groups. These results suggest that the expression of the leptin gene in response to food-deprivation and refeeding is influenced by an animal's age and that this expression is different for different regions of white adipose tissue.

Adipose Tissue↗
PubMed2000

Analysis of experimental autoimmune encephalomyelitis induced in F344 rats by pertussis toxin administration.

To elucidate the factor(s) accelerating the autoimmune disease processes, we induced two types of experimental autoimmune encephalomyelitis (EAE), severe and very mild, in F344 rats by immunization with myelin basic protein (MBP) plus pertussis toxin (PT) (PT+) or with MBP alone (PT-) and compared the differences between the two. Immunohistochemical examinations showed that although the nature of inflammation was essentially the same between the two groups, the proportion of Vbeta8.2(+) T cells in the CNS lesion of PT (+) rats was larger than that of PT (-) rats. Cytokine analysis by competitive PCR revealed that IL-10 mRNA in the lymphoid organ was significantly suppressed in the PT(+) group, whereas levels of IFN-gamma,TNF-alpha and TGF-beta mRNA were insignificantly different after PT administration. In addition, T cells taken from PT (+) rats proliferated well in response to MBP, while those from PT (-) rats showed a marginal response to the same antigen. However, this finding does not indicate the switching of non-encephalitogenic to encephalitogenic T cells upon PT administration because PT (-) rats contained encephalitogenic T cells and/or their precursor cells as revealed by adoptive transfer experiments. Taken together, these findings suggest that suppression of IL-10 by PT administration is the major factor contributing to the exacerbation of EAE in PT(+) rats.

Animals↗
PubMed2000

Real time monitoring of glutamate following fluid percussion brain injury with hypoxia in the rat.

In this study, extracellular glutamate (Glu) was monitored in real time using a biosensor following traumatic brain injury (TBI) either with or without inducing hypoxia in the rat Fluid-percussion model. We also measured the cortical contusion volume at 3 days after the insult. The animals were divided into 3 groups. Group 1 was subjected to TBI only, Group 2 to TBI followed by 20 min of moderate hypoxia (FiO2: 10%) and Group 3 to 20 min of moderate hypoxia without TBI. The surge increase in the extracellular Glu concentration occurred immediately after TBI in Groups 1 and 2. Group 2 showed a prolonged efflux of Glu during hypoxia. Group 3 Glu showed low continuous steady levels. The contusion volume in Group 2 was significantly larger than in Group 1. To test the possible involvement of apoptosis in Groups 1 and 2, rats were sacrificed at 1, 6, 24 and 72 h after TBI. Immunohistochemical studies showed an increased number of both CPP32 positive cells at 24 h and TUNEL cells at 72 h in Group 2. These results suggest that TBI with moderate hypoxia induced a prolonged efflux of Glu that resulted more cortical damage due to necrosis and apoptosis.

Animals↗
PubMed2000

The synergistic effect of high K+ and hypoxia on extracellular concentrations of neuroactive amino acid in hippocampus.

In the present study, we examined extracellular concentrations of glutamate (Glu) in hypoxia using ringer solution with a high potassium (K+) level using microdialysis. Based on our findings, we hypothesized that the concentration of extracellular K+ caused a greater efflux of Glu. We used male SD rats and separated them into 3 groups based on the K+ concentration of Ringer solution (RS), consisting of normal (4 mM), 40 mM and 150 mM groups. We stereotactically inserted the microdialysis probe into the hippocampus, and perfused the RS for 60 min before imposing hypoxia. Subsequently, while perfusing RS, hypoxia (7% O2 + 93% N2 gas) was induced in all 3 groups for 20 min. In the normal and 40 mM of K+ concentration groups, the Glu level did not increase, but in the 150 mM of K+ concentration group, the Glu level increased while being perfused with RS and a larger increase in Glu was observed after inducing hypoxia. This result suggests that the extracellular concentration of K+ plays a role in the mechanism of increased neuronal vulnerability caused by hypoxia after TBI.

Animals↗
PubMed2000

Mn-SOD and Bcl-2 expression after repeated hyperbaric oxygenation.

To clarify the mechanism of ischemic tolerance induced by HBO, we investigated the effect of HBO on immunoreactivity to Bcl-2 and Bax, apoptosis-regulating protein, or Mn-SOD, a radical scavenging system, in the CA1 sector of the gerbil hippocampus. Pretreatment comprising, five sessions at 2 ATA (atmosphere absolute) every other day, but not that comprising, ten sessions at 3 ATA every day, caused significant increases in Bcl-2 and Mn-SOD immunoreactivity in the CA1 sector compared with in the sham pretreatment group. No significant differences in Bax immunoreactivity and neuronal density in the CA1 hippocampal neurons was observed between the groups. These results suggest that protection against mitochondrial alterations after ischemia through Mn-SOD and/or Bcl-2 expression is related to the ischemic tolerance induced by repeated HBO pre-treatment.

Animals↗
PubMed2000

Hepatocyte growth factor reduces infarct volume after transient focal cerebral ischemia in rats.

Hepatocyte growth factor (HGF) was originally discovered as a powerful mitogen for hepatocytes. HGF functions both as a neurotrophic factor as well as an angiogenetic factor. Furthermore, HGF has an anti-apoptotic effect on vascular endothelial cells. The present study examined the neuroprotective effect of HGF after transient focal cerebral ischemia in rats, in which an anti-apoptotic and an angiogenetic effect of HGF was assumed to contribute to the reduction of the infarct volume. The intraventricular administration of human recombinant HGF (90 micrograms) significantly reduced the infarct volume after 120 minutes occlusion of both the right middle cerebral artery (MCA) and the bilateral common carotid arteries (CCAs). In a separate series of experiments, we investigated both the anti-apoptotic effect on neurons and the angiogenetic effect of HGF histopathologically. The number of survival neurons and vascular lumina in the HGF group were significantly higher than those in the vehicle group. A large number of TUNEL positive neurons were observed in the inner boundary of the infarct area in the vehicle group, whereas only a few TUNEL positive neurons were observed in a corresponding area in the HGF group. In the HGF group, Bcl-2 protein was obviously represented in survival neurons as well as in vascular endothelial cells and in glial cells subjected to ischemia. These data suggest that HGF prevents apoptotic neuronal cell death by upregulating the production of Bcl-2 protein and by an angiogenetic effect in the central nervous system which affected transient focal cerebral ischemia.

Animals↗
PubMed2000

Early experiences of haemostasis on brain tumour surgery with Argon Plasma Coagulation (APC).

OBJECTIVE: We first applied a novel haemostatic strategy involving Argon Plasma Coagulation (APC), an innovative no-touch electrocoagulation technique in which a high-frequency alternating current is delivered to the tissue through ionized argon gas, to brain tumour surgery, and report its usefulness and limitations. METHODS: The APC system we used comprised an APC 300 developed by ERBE Elektromedizin GmbH, Germany. We applied APC to 13 brain tumours in 12 patients (5 meningiomas, 4 sarcomas, 2 glioblastomas, and 2 pituitary adenomas). To avoid unnecessary thermal injury to the tissue as much as possible, power/gas flow settings of 20 and 40 W were used. The impact time was varied individually but was around several seconds per one impact. The argon jet (1.5-4.5 L/min) clears a field of pooled blood and evenly conducts electrical energy to the target tissue. A thin and flexible probe particularly increased the usefulness of APC for haemostasis on deep-seated skull base tumour operations under a microscope. CONCLUSION: All patients were successfully treated and satisfied with the surgical results without any complications due to APC. APC appears to be an excellent alternative strategy for achieving haemostasis on vascular-rich brain tumour surgery, and may be valuable for the management of patients with coagulation defects.

Adenoma↗
PubMed2000

Cystic schwannoma of the orbit: case report.

BACKGROUND: Cystic lesions of the orbit have diverse clinical findings and histopathological features. We report an orbital schwannoma composed of a single cyst. CASE DESCRIPTION: A 62-year-old woman with an intraconal cystic tumor in the left orbital cavity is described. The cystic tumor was totally removed and the pathological diagnosis of the cyst wall was schwannoma composed of both Antoni type A and B. CONCLUSIONS: A rare case of cystic schwannoma of the orbit is reported. This case may contribute to an improved preoperative differential diagnosis for cystic lesions of the orbit.

Cysts↗
PubMed2000

Incidence of human papillomavirus 16 and 18 infection and p53 mutation in patients with oral squamous cell carcinoma in Japan.

The purpose of this study was to investigate the prevalence of human papillomaviruses (HPVs) 16 and 18 infection, and p53 mutation in oral squamous cell carcinomas (SCCs) in Japanese patients. Our results showed a higher incidence of HPV16 and 18 infections than previous studies because we combined the findings of a consensus polymerase chain reaction (PCR), restriction fragment length polymorphism by using the restriction enzyme digestion of the PCR products and Southern blot hybridization. Each HPV16 and 18 E6/E7 DNA was detected in 9 (20%) and 25 (54%) of 46 samples. The p53 mutation in the exons from 5 to 8 were detected in 20 out of 46 samples (43%) by a PCR-single strand conformation polymorphism analysis. There was a significant relationship between HPV16 and the p53 mutation (P =0.02) suggesting that HPV16 infection has a mutagenic effect in oral SCC. However, neither HPV infection nor p53 mutation influenced survival.

Adult↗
PubMed2000

Real-time monitoring of glutamate following fluid percussion brain injury with hypoxia in the rat.

In the present study, extracellular glutamate (Glu) was monitored in real time using an enzyme electrode biosensor following traumatic brain injury (TBI) either with or without inducing hypoxia in the rat. We also measured the cortical contusion volume at 3 days after insult by staining with 2,3,5-triphenyltetrazolium chloride (TTC). Male Sprague-Dawley rats (300-400 g) were anesthetized and then subjected to lateral fluid percussion (FP) brain injury of moderate severity (3.5-4.0 atm), using the Dragonfly device model (no. HPD-1700). The experimental animals were divided into four groups. Group 1 (n = 10) was subjected to TBI only, group 2 (n = 10) to TBI followed by 20 min of moderate hypoxia (FiO2: 10%), group 3 (n = 4) to 20 min of moderate hypoxia without TBI, and group 4 (n = 4) to sham. Seventy-two hours after the insults, the animals were sacrificed, their brains were stained with TTC, and the lesion volumes were calculated. A surge in the extracellular Glu concentration occurred immediately after TBI in groups 1 and 2. There was no significant difference between the two groups. Group 2 showed a prolonged efflux of Glu during hypoxia ( < 0.05). In group 3, Glu continued to show a mild increase. The cortical contusion volume in group 2 was significantly larger than that in group 1. To evaluate the possible involvement of apoptosis in groups 1 and 2, separate rats were sacrificed under the same procedures after 1, 6, 24, and 72 h after insult (n = 2/group). Immunohistochemical analysis demonstrated an increased number of both the cysteine protease caspase-3-positive cells at 24 h and TUNEL-positive cells at 72 h in group 2. These results suggest that TBI with moderate hypoxia induced the prolonged efflux of Glu, which thus resulted in more cortical damage due to necrosis and apoptosis.

Animals↗
PubMed2000

High susceptibility to cerebral ischemia in GFAP-null mice.

Astrocytes perform a variety of functions in the adult central nervous system (CNS) that contribute to the survival of neurons. Thus, it is likely that the activities of astrocytes affect the extent of brain damage after ischemic stroke. The authors tested this hypothesis by using a mouse ischemia model to compare the infarct volume produced in wild-type mice with that produced in mice lacking glial fibrillary acidic protein (GFAP), an astrocyte specific intermediate filament component. Astrocytes lacking GFAP have been shown to have defects in process formation, induction of the blood-brain barrier. and volume regulation; therefore, they might be compromised in their ability to protect the CNS after injury. The authors reported here that 48 hours after combined permanent middle cerebral artery occlusion (MCAO) and 15 minutes transient carotid artery occlusion (CAO) GFAP-null mice had a significantly (P < 0.001) larger cortical infarct volume (16.7 +/- 2.2 mm3) than their wild-type littermates (10.1 +/- 3.9 mm3). Laser-Doppler flowmetry revealed that the GFAP-null mice had a more extensive and profound decrease in cortical cerebral blood flow within 2 minutes after MCAO with CAO. These results indicated a high susceptibility to cerebral ischemia in GFAP-null mice and suggested an important role for astrocytes and GFAP in the progress of ischemic brain damage after focal cerebral ischemia with partial reperfusion.

Animals↗
PubMed2000

A quantitative analysis of head injury using T2*-weighted gradient-echo imaging.

BACKGROUND: T2*-weighted gradient-echo imaging (T2*-GE) is useful for detecting small hemorrhages. METHODS: Thirty-four patients were prospectively examined, first by magnetic resonance imaging (1.5 T) and then by T2-weighted fast spin echo (T2-FSE) and T2*-GE. Thereafter, the correlations between the T2-FSE or T2*-GE findings and the clinical or computed tomography findings were analyzed. RESULTS: The number of lesions detected by T2*-GE was 14.5 +/- 16.3 (mean +/- SD, n = 34), which was significantly (p < 0.001) greater than that detected by T2-FSE (5.6 +/- 5.6, n = 34). The findings of T2*-GE correlated positively with both the duration of unconsciousness (R2 = 0.74,p < 0.0001) and with Glasgow Outcome Scale (R2 = 0.81, p < 0.0001), whereas those of T2-FSE did not show any significant correlation. T2*-GE imaging could also detect all areas responsible for focal neurologic signs 1 month after in. jury, whereas T2-FSE imaging detected only 22 of 33 such signs. CONCLUSION: T2*-GE was found to be useful for evaluating the clinical symptoms of head injury.

Adolescent↗
PubMed2000

Neuronal activity in the primate prefrontal cortex in the process of motor selection based on two behavioral rules.

This study examined neuronal activity in the prefrontal cortex (PF) involved in the process of motor selection in accordance with two behavioral rules. We trained two monkeys to select a target based on the integration of memorized and current sensory information. Initially, a sample cue (triangle or circle) appeared at one of three locations (top, left, or right) for 1 s. After a 3-s delay, one of two types of choice cue appeared. The first type asked the monkeys to reach for a target by matching the location (location-matching task). The second type asked the monkeys to reach for a target by matching the shape (shape-matching task). The choice cue for location matching consisted of either three circles or three triangles, and the choice cue for shape matching consisted of a circle and a triangle. When the color of the choice cue changed from red to green 1.5 s later (GO signal), the monkeys touched the correct object to obtain a reward. We found cue-, delay-, choice-, and movement-related neuronal activity in the lateral prefrontal cortex. During the sample cue presentation and delay periods, we found selective neuronal activity for the location or shape of the sample cue. Shape-selective neurons were located more anteriorly in the ventral bank of the principal sulcus and inferior convexity area, whereas location-selective neurons were more posteriorly. After the choice cue appeared, we found three main types of neuronal activity in the critical period when the subject selected the future target: 1) activity reflecting past sensory information (the location or shape of the sample cue presented 3 s earlier), 2) activity selective for the configuration of the current choice cue, and 3) activity reflecting the properties (location or shape) of the future target. During the motor-response period, we found neuronal activity selective for the location or shape of the reaching target. When muscimol was microinjected into the ventral bank of principal sulcus and inferior convexity area, the performance of both tasks was impaired. Furthermore, we found that the wealth of neuronal activity in the PF that seemed to play a role in motor selection was rarely seen in the primary motor cortex.

Animals↗
PubMed2000

Neuronal activity in the supplementary and presupplementary motor areas for temporal organization of multiple movements.

To study how neurons in the medial motor areas participate in performing sequential multiple movements that are individually separated in time, we analyzed neuronal activity in the supplementary (SMA) and presupplementary (pre-SMA) motor areas. Monkeys were trained to perform three different movements separated by waiting times, in four or six different orders. Initially each series of movements was learned during five trials guided by visual signals that indicated the correct movements. The monkeys subsequently executed the three movements in the memorized order without the visual signals. Three types of neuronal activity were of particular interest; these appeared to be crucially involved in sequencing the multiple motor tasks in different orders. First, we found activity changes that were selective for a particular sequence of the three movements that the monkeys were prepared to perform. The sequence-selective activity ceased when the monkeys initiated the first movement. Second, we found interval-selective activity that appeared in the interval between one particular movement and the next. Third, we found neuronal activity representing the rank order of three movements arranged chronologically; that is, the activity differed selectively in the process of preparing the first, second, or third movements in individual trials. The interval-selective activity was more prevalent in the SMA, whereas the rank-order selective activity was more frequently recorded in the pre-SMA. These results suggest how neurons in the SMA and pre-SMA are involved in sequencing multiple movements over time.

Animals↗
PubMed2000

Serum leptin profiles in the normal menstrual cycles and gonadotropin treatment cycles.

Circulating levels of leptin, estradiol (E(2)) and progesterone (P(4)) throughout normal menstrual cycles (n = 13), and controlled, stimulated cycles (n = 33) were examined using sensitive specific radioimmunoassays in order to investigate the relationships between sex hormones (E(2), P(4)). Serum leptin levels during the normal menstrual cycle remained constant. However, in the ovulation induction cycle, E(2) levels and circulating leptin levels increased in parallel with the process of stimulation. In addition, leptin/body mass index ratios for all samples were significantly correlated with log(10)E(2). We conclude that particularly high levels of E(2) may have an effect on the secretion of leptin from adipose tissue.

Adult↗