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Biomedical subjects

T Shioiri

Publications and source records attributed to T Shioiri.

At least 19 recordsLinked to original sources
PubMed1999

Binding of [3H]U-101958 to sigma1 receptor-like sites in human cerebellum and neuroblastoma cells.

1-Benzyl-4-[N-(3-isopropoxy-2-pyridinyl)-N-methyl]-amino-piperidine ([3H]U-101958), a dopamine D4 receptor ligand, was found to bind to a large sigma1 receptor-like component in human cerebellum and SK-N-MC neuroblastoma cells with high affinity (2-4 nM Kd). By contrast, binding to dopamine D4 receptors represented 10% or less of the sigma1 receptor-like site. Considering that U-101958 has been characterized as either a dopamine D4 receptor agonist or antagonist, depending on the system under study, the observation that U-101958 also binds to sigma1 receptor-like sites is important for accurate interpretation of the pharmacological actions of this compound. [3H]U-101958 may be a useful radioligand for sigma1 rather than dopamine D4 receptor sites.

Aminopyridines↗
PubMed1999

Age-dependent alteration of metabolic response to photic stimulation in the human brain measured by 31P MR-spectroscopy.

Effects of photic stimulation (PS) on energy metabolism were examined in the occipital cortex of 25 healthy volunteers aged 23-69 years old using phosphorus-31 magnetic resonance spectroscopy (31P-MRS). A significant effect of photic stimulation was found only for intracellular pH (p<0.05 by repeated measures analysis of variance) but not for any peak area ratios. An interaction between intracellular pH and age were statistically significant (p<0.005), and the interaction between phosphocreatine and age was close to significance (p=0.06). In subjects aged more than 40 years old, phosphocreatine was significantly decreased during the photic stimulation (p<0.05, multiple comparison by Dunnett's method), and intracellular pH tended to be elevated just after the stimulation (p=0.07). There were no significant changes in these values in younger subjects. These results suggest that no significant effect of photic stimulation on brain energy metabolism was found in younger subjects, and that significant effects of photic stimulation on intracellular pH and phosphocreatine were found in middle-aged subjects. Metabolic response of the human brain to photic stimulation may be dependent on age.

Adult↗
PubMed1999

Conformational change of ascidiacyclamide caused by asymmetric modification for an isoleucine residue: structural analyses of [Gly], [Leu], and [Phe]ascidiacyclamides by x-ray diffraction and NMR spectroscopy.

Ascidiacyclamide, a cytotoxic cyclic peptide from tunicate, is composed of unusual amino acids and has a repeated sequence, c[-thiazole-D-Val-oxazoline-L-Ile-]2 ([Ile]ASC). The symmetric chemical structure has been assumed to be correlated with the cytotoxicity, and it is reasonable to consider that the disturbance of its structure from the C2 symmetry results in the changes of conformation and activity. In order to quantitatively estimate the molecular conformation-activity relationship, an isoleucine residue was substituted by Gly, Leu, or Phe to disturb the C2 symmetry. The conformations of three derivatives were examined by nmr spectroscopy and the crystal structure of [Leu]ASC was also analyzed by x-ray diffraction method. The 1H-nmr experiments and the constrained molecular dynamics simulations showed the twisted "figure 8" conformers for [Gly] and [Phe]ASCs and the "square" conformer for [Leu]ASC in the DMSO solution. The x-ray crystal analysis of [Leu]ASC also revealed the square form similar to the solution structure. On the other hand, their cytotoxic activities were measured using L1210 leukemia cells and were related with the bulkiness and/or hydrophobicity of the side chain of the substituted amino acid; [Phe] > or = [Ile] > [Leu] >> [Gly]ASCs. As an attempt to consider the correlation between the activity and conformer, the accessible surface area (ASA) was calculated for each derivative to estimate the size or bulkiness of its conformation. Although the ASAs of nmr structures were not directly related to the type of conformer (figure 8 or square form), it was an important probe to consider the cytotoxicity of each derivative.

Amino Acid Substitution↗
PubMed1999

Quantitative proton magnetic resonance spectroscopy of the bilateral frontal lobes in patients with bipolar disorder.

BACKGROUND: Using 31P and 1H magnetic resonance spectroscopy (MRS) we previously reported that phosphocreatine was decreased in the left frontal lobe and choline-containing compounds were increased in the basal ganglia in the depressive state in patients with bipolar disorder. We applied quantitative 1H-MRS for further characterization of biochemical alteration in the frontal lobes of bipolar patients. METHODS: Twenty-three bipolar patients and 20 normal controls were examined by 1H-MRS with a 1.5T MR system. All patients were examined in the euthymic state, and eight patients were also examined in the depressive state. Volumes of interest of 2.5 x 2.5 x 2.5 cm were selected in the left and right frontal lobes. Absolute concentrations of N-acetyl-1-aspartate, creatine plus phosphocreatine, and choline-containing compounds were calculated from each metabolite peak. RESULTS: Creatine concentration in the left frontal lobe in bipolar patients in the depressive state was significantly lower than that in the euthymic state. Creatine concentration in the right frontal lobe in the male patients was significantly higher than that in the female patients and a similar trend was also found in the control subjects. CONCLUSIONS: We found a state-dependent change of creatine metabolism in the left frontal lobe of bipolar patients. The present results are compatible with our previous report of decreased phosphocreatine measured by 31P-MRS in the left frontal lobe in bipolar disorder. We also found an effect of gender on the creatine concentration. There may be a gender difference in creatine transport function into the brain.

Adult↗
PubMed1999

Misinterpretation of facial expression: a cross-cultural study.

Accurately recognizing facial emotional expressions is important in psychiatrist-versus-patient interactions. This might be difficult when the physician and patients are from different cultures. More than two decades of research on facial expressions have documented the universality of the emotions of anger, contempt, disgust, fear, happiness, sadness, and surprise. In contrast, some research data supported the concept that there are significant cultural differences in the judgment of emotion. In this pilot study, the recognition of emotional facial expressions in 123 Japanese subjects was evaluated using the Japanese and Caucasian Facial Expression of Emotion (JACFEE) photos. The results indicated that Japanese subjects experienced difficulties in recognizing some emotional facial expressions and misunderstood others as depicted by the posers, when compared to previous studies using American subjects. Interestingly, the sex and cultural background of the poser did not appear to influence the accuracy of recognition. The data suggest that in this young Japanese sample, judgment of certain emotional facial expressions was significantly different from the Americans. Further exploration in this area is warranted due to its importance in cross-cultural clinician-patient interactions.

Adolescent↗
PubMed1999

Cultural difference in recognition of facial emotional expression: contrast between Japanese and American raters.

Using the Japanese and Caucasian Facial Expressions of Emotion (JACFEE) photo set, the relationship between recognition and intensity ratings of universal facial expressions of emotions in 123 Japanese undergraduate students was examined and compared with data reported by American raters. In Japanese raters, although the intensity was rated as high for some of the poses, their correctness scores were poor, suggesting a serious misjudgment of the intended emotions as defined in the JACFEE photo set. Only in Japanese raters were significant relationships between the intensity scores and the percentage correctness scores for sadness detected (r = 0.97, P < 0.0001), but no significant relationship was observed for other emotions. The robust correlation suggests the possibility that Japanese raters might be more responsive to certain emotional expressions when they are fully or intensely expressed. It is proposed that the facial emotional expression paradigm cannot be applied to the psychiatric setting without first refining for cultural differences.

Adult↗
PubMed1999

Nicotianamine chelates both FeIII and FeII. Implications for metal transport in plants

Nicotianamine (NA) occurs in all plants and chelates metal cations, including FeII, but reportedly not FeIII. However, a comparison of the FeII and ZnII affinity constants of NA and various FeIII-chelating aminocarboxylates suggested that NA should chelate FeIII. High-voltage electrophoresis of the FeNA complex formed in the presence of FeIII showed that the complex had a net charge of 0, consistent with the hexadentate chelation of FeIII. Measurement of the affinity constant for FeIII yielded a value of 10(20.6), which is greater than that for the association of NA with FeII (10(12.8)). However, capillary electrophoresis showed that in the presence of FeII and FeIII, NA preferentially chelates FeII, indicating that the FeIINA complex is kinetically stable under aerobic conditions. Furthermore, Fe complexes of NA are relatively poor Fenton reagents, as measured by their ability to mediate H2O2-dependent oxidation of deoxyribose. This suggests that NA will have an important role in scavenging Fe and protecting the cell from oxidative damage. The pH dependence of metal ion chelation by NA and a typical phytosiderophore, 2'-deoxymugineic acid, indicated that although both have the ability to chelate Fe, when both are present, 2'-deoxymugineic acid dominates the chelation process at acidic pH values, whereas NA dominates at alkaline pH values. The consequences for the role of NA in the long-distance transport of metals in the xylem and phloem are discussed.

Journal Article↗
PubMed1999

Cloning two genes for nicotianamine aminotransferase, a critical enzyme in iron acquisition (Strategy II) in graminaceous plants.

Nicotianamine aminotransferase (NAAT), the key enzyme involved in the biosynthesis of mugineic acid family phytosiderophores (MAs), catalyzes the amino transfer of nicotianamine (NA). MAs are found only in graminaceous plants, although NA has been detected in every plant so far investigated. Therefore, this amino transfer reaction is the first step in the unique biosynthesis of MAs that has evolved in graminaceous plants. NAAT activity is dramatically induced by Fe deficiency and suppressed by Fe resupply. Based on the protein sequence of NAAT purified from Fe-deficient barley (Hordeum vulgare) roots, two distinct cDNA clones encoding NAAT, naat-A and naat-B, were identified. Their deduced amino acid sequences were homologous to several aminotransferases, and shared consensus sequences for the pyridoxal phosphate-binding site lysine residue and its surrounding residues. The expression of both naat-A and naat-B is increased in Fe-deficient barley roots, while naat-B has a low level of constitutive expression in Fe-sufficient barley roots. No detectable mRNA from either naat-A or naat-B was present in the leaves of either Fe-deficient or Fe-sufficient barley. One genomic clone with a tandem array of naat-B and naat-A in this order was identified. naat-B and naat-A each have six introns at the same locations. The isolation of NAAT genes will pave the way to understanding the mechanism of the response to Fe in graminaceous plants, and may lead to the development of cultivars tolerant to Fe deficiency that can grow in calcareous soils.

Amino Acid Sequence↗
PubMed1999

Relationship of energy metabolism detected by 31P-MRS in the human brain with mental fatigue.

To search for a possible relationship between brain energy metabolism and mental fatiguability, 10 normal volunteers were examined by 31P-MRS (phosphorus-31 magnetic resonance spectroscopy) in the occipital cortex during photic stimulation (PS), and Uchida-Kraepelin test (UKT), a standardized serial calculation task, was used for measurement of intraindividual characteristics of mental fatigue in these subjects. More decrease of phosphocreatine measured by 31P-MRS during the PS was significantly associated with more effects of rest assessed by UKT (r = -0.86, p <0.005). More decrease in pH after PS was associated with steeper decline of performance (r = 0.78, p <0.01). These findings suggest that characteristics of brain energy metabolism in an individual may relate to intrinsic patterns of mental fatigability.

Adult↗
PubMed1998

Photic stimulation-induced alteration of brain energy metabolism measured by 31P-MR spectroscopy in patients with MELAS.

We examined brain energy metabolism by phosphorus-31 magnetic resonance spectroscopy (31P-MRS) in the occipital cortex in a mother and a daughter with MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes) during photic stimulation. The peak area ratio of phosphocreatine markedly decreased during photic stimulation, and subsequently increased after the stimulation. This method, photic stimulation-31P-MRS, may be useful in assessing brain energy metabolism in neurological diseases.

Adult↗
PubMed1998

Decreased brain intracellular pH measured by 31P-MRS in bipolar disorder: a confirmation in drug-free patients and correlation with white matter hyperintensity.

The authors have previously reported decreased intracellular pH (pHi) in the frontal lobes in euthymic bipolar patients treated with lithium using 31P-MRS. White matter hyperintensity (WMHI) is frequently seen in bipolar disorder. To examine a possible effect of lithium on pHi and the relationship between pHi and WMHI, seven drug-free euthymic bipolar patients were examined, and T2-weighted MRI were examined in 14 previously reported bipolar patients. Drug-free patients showed significantly lower pHi than controls. WMHI was associated with low pHi and increased phosphodiester peak. These results suggest that decrease of pHi is not an effect of lithium but is instead related to the pathophysiology of illness. Decrease of pHi and increase of the PDE peak may be the biochemical basis of WMHI in bipolar disorder.

Adult↗
PubMed1998

Frequency distribution of serum cholesterol levels in patients with panic disorder: comparison with normal controls.

We compared the frequency distribution of total cholesterol (TC) levels in 103 patients with panic disorder (PD) with that in 173 gender- and age-matched normal controls (NC). There was no significant difference in the mean TC level between the PD and the NC groups. The distribution of TC levels in the PD group was similar to that in the NC group. As a whole distribution pattern, there is no association between high serum cholesterol levels and panic disorder. However, four male PD patients had very high TC levels of more than 260 mg/dL, and two of them had obviously deviated values from the frequency distribution of TC levels in the NC group. Our findings are supportive of the view that male PD patients with high TC levels have excess mortality due to cardiovascular diseases.

Adult↗
PubMed1997

Multiple regression analysis of relationship between frontal lobe phosphorus metabolism and clinical symptoms in patients with schizophrenia.

We investigated the differences among diagnostic types of 36 schizophrenic patients in the brain phosphorus metabolism in the frontal lobe. We performed phosphorus-31 magnetic resonance spectroscopy (31P-MRS) in the frontal region in patients with schizophrenia of the catatonic (n = 4), disorganized (n = 8), paranoid (n = 10) and undifferentiated (n = 14) types. In the disorganized type, the PME level was significantly decreased compared to those in the other three types, while the phosphodiester (PDE) level tended to be higher, although not significantly, than those in the other types. Using multiple regression analysis, we investigated whether or not the clinical symptoms were correlated with the brain phosphorus metabolism. An increased motor retardation factor score was significantly correlated with decreased PME level, whereas more severe emotional withdrawal and blunted affect were associated with increased PDE level. These results suggest that altered membrane phospholipid metabolism in the frontal region may be associated with negative symptoms and that schizophrenia of the disorganized type is associated with more severe negative symptoms and may present more severe brain abnormalities compared to the other types.

Adolescent↗
PubMed1997

Phosphorus-31 magnetic resonance spectroscopic observations in 4 cases with anorexia nervosa.

1. Brain phosphorus metabolism was examined using phosphorus-31 magnetic resonance spectroscopy in 4 patients with anorexia nervosa. 2. In 4 patients examined before treatment, phosphodiester (PDE) peak area was significantly higher than that in 13 normal females. 3. In 6 data points in 4 patients, lower levels of PME were associated with malnutrition reflected by endocrinological abnormalities. 4. These data suggest that severe malnutrition in patients with anorexia nervosa may result in abnormality in membrane phospholipid metabolism, which might be responsible for brain atrophy in anorexia nervosa.

Adult↗
PubMed1997

Differences in symptom structure between panic attack and limited symptom panic attack: a study using cluster analysis.

We had investigated the clinical characteristics of panic disorder (PD) in a Japanese outpatient population comprised of more than 250 patients diagnosed as having PD during a 13-year study period and observed that some PD patients had both panic attacks (PA) and limited symptom panic attacks (LPA). In the criteria for PD based on the Diagnostic and Statistics Manual of Mental Disorders, third edition-revised (DSM-III-R), episodes involving four or more symptoms are classified as PA, while those involving fewer than four symptoms are described as LPA. Therefore, LPA is identified as part of an episode of PA, since the difference between the two episodes is only in the number of symptoms. However, some recent research suggests that there is a distinct subgroup of individuals who suffer LPA. Using cluster analysis, we investigated the differences between PA and LPA groups in terms of the structures of several panic symptoms, which included anticipatory anxiety, agoraphobia and 13 clinical symptoms based on the DSM-III-R at the time of panic attacks, in 247 patients with PD. Cluster analysis revealed clusters of three and four panic symptoms in the PA group and LPA group, respectively, and there were also differences in symptom structure between the two groups. These results suggest that there may be a subgroup of individuals who show LPA among PD patients.

Adult↗