Biomedical subjects

Miho Ota

Publications and source records attributed to Miho Ota.

11 recordsLinked to original sources

PubMed2006

Relationship between diffusion tensor imaging and brain morphology in patients with myotonic dystrophy.

Myotonic dystrophy type 1 (MyD) is a common inherited neuromuscular disorder. In addition to neuromuscular symptoms, many MyD patients show central nervous system neuropathology. This study evaluated whether MyD patients display diffusion tensor (DT) abnormalities associated with regional cortical atrophy and clinical features. Three-dimensional T1-weighted and DT magnetic resonance images of the brain were obtained in 11 MyD patients and 13 age- and sex-matched healthy subjects. Fractional anisotropy (FA) and mean diffusivity (MD) values were calculated in corpus callosum subregions with DT imaging (DTI) along with volumetric changes, and correlations with clinical features were examined. Differences between MyD patients and healthy subjects were analyzed statistically. Significantly lower FA and higher MD values were found in the genu, rostral body, anterior midbody, posterior midbody and splenium in MyD patients than in control subjects (p<0.05, corrected; lower FA in the splenium was at a trend level). These corpus callosum subregions were the areas connected to cortical areas where significantly lower volumes were found in MyD patients. No significant decrease in volumes was noted in the parietal cortex, where connecting fibers pass through the isthmus in which DTI abnormalities were not detected in MyD patients. Significant negative correlations to volumes of frontal areas were noted, particularly bilateral motor areas, with cytosine thymine guanidine (CTG) triplet expansion. DTI results in corpus callosum may reflect morphological changes in the connecting cortical areas of MyD patients.

Brain↗

PubMed2006

Role of ventral striatal dopamine D1 receptor in cigarette craving.

BACKGROUND: Several theories of cigarette craving suggest that dopaminergic function in the ventral striatum plays an important role. The objective of this study was to determine correlations between craving-related brain activation and dopamine D1 receptor (D1R) binding in smokers. METHODS: Twelve smokers and 12 nonsmoking controls underwent [(15)O]H(2)O-positron emission tomography activation study and D1R-binding study using [(11)C]SCH 23390, and the correlations between receptor binding and cue-induced regional cerebral blood flow (rCBF) changes were assessed. Consecutive D1R-binding changes were examined during a period of 6 months of postsmoking abstinence in five smokers. RESULTS: Cue-induced activation was observed in the left ventral striatum including the nucleus accumbens in smokers. D1R binding in the ventral striatum showed a negative relationship with cue-induced craving and rCBF changes. D1R binding was significantly low in smokers, and there was a trend of increase after smoking abstinence. CONCLUSIONS: D1R binding and cue-induced rCBF changes in the ventral striatum suggest the important role of D1R in this region in cigarette craving.

Adult↗

PubMed2006

Quantitative analysis for estimating binding potential of the peripheral benzodiazepine receptor with [(11)C]DAA1106.

[(11)C]DAA1106 is a potent and selective ligand for the peripheral benzodiazepine receptor (PBR) with high affinity. It has been reported that the density of PBR is related to brain damage, so a reliable tracer method for the evaluation of PBR would be of use. We evaluated a quantification method of [(11)C]DAA1106 binding in simulated data and human brain data. In the simulation study, the reliability of parameters estimated from the nonlinear least-squares (NLS) method, graphical analysis (GA), and multilinear analysis (MA) was evaluated. In GA, variation of the estimated distribution volume (DV) was small. However, DV was underestimated as noise increased. In MA, bias was smaller, and variation of the estimated DV was larger than in GA. In NLS, although variation was larger than in GA, it was small enough in regions of interest analysis, and not only DV but also binding potential (BP), determined from the k(3)/k(4) without any constraint, could be estimated. The variation of BP estimated with NLS became larger as k(3) or k(4) became smaller. In human studies with normal volunteers, regions of interest were drawn on several brain regions, BP was calculated by NLS, and DV was also estimated by NLS, GA, and MA. As a result, DVs estimated with each method were well correlated. However, there was no correlation between BP with NLS and DV with NLS, GA, and MA, because of the variation of K(1)/k(2) between individuals. In conclusion, BP is estimated most reliably by NLS with the two-tissue compartment model.

Acetamides↗

PubMed2006

Age-related degeneration of corpus callosum measured with diffusion tensor imaging.

The corpus callosum is the major commissure connecting the cerebral hemispheres, and there is evidence of its change with aging. The sub-regions of the corpus callosum (genu, rostral body, anterior midbody, posterior midbody, isthmus, splenium) respectively comprise fibers connecting heteromodal- and unimodal-associated cortical regions, and it is known that abnormalities of the corpus callosum are correlated with abnormalities in cognition and behavior. Yet, little is known about changes in the tissue characteristics of its sub-regions. We assessed age-related changes in fractional anisotropy and mean diffusivity in the sub-regions of the corpus callosum using diffusion tensor imaging. We studied 42 healthy right-handed individuals aged 21-73 years. There were no significant interactions of sex x region. Age has significant negative correlation with fractional anisotropy in the genu (P < 0.001), rostral body (P < 0.001), and isthmus (P = 0.005). Fractional anisotropy of the anterior midbody was correlated negatively with age at a trend level (P = 0.022). Age was significantly positively correlated with mean diffusivity in the genu (P = 0.001), rostral body (P = 0.002), anterior midbody (P = 0.001), and isthmus (P = 0.001). Age-related changes were detected in the sub-regions where their projection areas are thought to be vulnerable to normal aging. This suggested that fractional anisotropy and mean diffusivity values of the corpus callosum sub-regions could serve as markers of disturbance across the respective projection areas.

Adult↗

PubMed2006

Age-related decline of dopamine synthesis in the living human brain measured by positron emission tomography with L-[beta-11C]DOPA.

Loss of dopamine synthesis in the striatum with normal human aging has been observed in the postmortem brain. To investigate whether there is age-associated change in dopamine synthesis in the extrastriatal brain regions similar to that in the striatum, positron emission tomography studies with (11)C-labelled l-DOPA were performed on 21 normal healthy male subjects (age range 20-67 years). Decline in the tissue fraction of gray matter per region of interest was also investigated. The overall uptake rate constant for each region of interest was quantified by the Patlak plot method using the occipital cortex as reference region. Regions of interest were set on the dorsolateral prefrontal cortex, lateral temporal cortex, medial temporal cortex, occipital cortex, parietal cortex, anterior cingulate, thalamus, midbrain, caudate nucleus, and putamen. Test-retest analysis indicated good reproducibility of the overall uptake rate constant. Significant age-related declines of dopamine synthesis were observed in the striatum and extrastriatal regions except midbrain. The decline in the overall uptake rate constant was more prominent than in the tissue fraction of gray matter. These results indicate that the previously demonstrated age-related decline in striatal dopamine synthesis extends to several extrastriatal regions in normal human brain.

Adult↗

PubMed2006

A dose-finding study of duloxetine based on serotonin transporter occupancy.

RATIONALE: Positron emission tomography (PET) has been utilized for determining the dosage of antipsychotic drugs. To evaluate the dosage of antidepressants such as selective serotonin reuptake inhibitors, serotonin transporter occupancy (5-HTT) is also a useful index. OBJECTIVES: We investigated the degree of 5-HTT occupancy with different doses of the antidepressant duloxetine and the time-course of 5-HTT occupancy using PET. METHODS: PET scans with [11C]DASB were performed before and after a single administration of duloxetine (5-60 mg), and three consecutive scans were performed after a single dose or repeated doses of 60 mg of duloxetine. RESULTS: 5-HTT occupancies by duloxetine were increased by 35.3 to 86.5% with dose and plasma concentration increments. The ED50 value of 5-HTT occupancy was 7.9 mg for dose and 3.7 ng/ml for plasma concentration. In the time-course of 5-HTT occupancy, mean occupancies were 81.8% at 6 h, 71.9% at 25 h, and 44.9% at 53 h after a single administration, and 84.3% at 6 h, 71.9% at 49 h, and 47.1% at 78 h after repeated administrations. CONCLUSIONS: Based on 5-HTT occupancy, 40 mg and more of duloxetine was needed to attain 80% occupancy, and 60 mg of duloxetine could maintain a high level of 5-HTT occupancy with a once-a-day administration schedule.

Adult↗

PubMed2006

Quantitative analysis of dopamine synthesis in human brain using positron emission tomography with L-[beta-11C]DOPA.

BACKGROUND AND OBJECTIVES: To estimate the presynaptic function of the central dopaminergic system, the rate of endogenous dopamine synthesis has been measured by using L-[beta-C]DOPA or 6-[F]fluoro-L-DOPA with positron emission tomography. However, the regional kinetics of L-[beta-C]DOPA in human brain have not been investigated in detail. In the present study, the regional kinetics of L-[beta-C]DOPA in normal human brain and the accuracy of the method for quantifying L-[beta-C]DOPA kinetics, employing reference regions, were investigated. METHODS: After intravenous injection of L-[beta-C]DOPA, dynamic scanning was performed on ten healthy subjects for 89 min. The overall uptake rate constant K was calculated by the kinetic and graphical approaches, in which the occipital cortex was used as a reference brain region. RESULTS: Regional distribution of K was similar to those of dopamine D2 receptor. A significant negative correlation was observed between the neutral amino acid concentration in plasma and the influx rate constant through the blood-brain barrier (K1). The K values calculated by graphical approach were in good agreement with the values calculated by kinetic approach for both experimental and simulated data. CONCLUSIONS: The regional distribution of K corresponds to that of the nigrostriatal and mesolimbic dopaminergic system. Negative correlation between neutral amino acid concentration and K1 supports the suggestion that L-DOPA is transported in a competitive fashion via the same carrier system as neutral amino acids at the blood-brain barrier. Because the graphical approach can obviate the need for an arterial input function, it is useful for investigating the rate of regional dopamine synthesis in neuropsychiatric and neurodegenerative diseases.

Adult↗

PubMed2006

Quantitative analyses of 18F-FEDAA1106 binding to peripheral benzodiazepine receptors in living human brain.

UNLABELLED: N-(5-Fluoro-2-phenoxyphenyl)-N-(2-(18)F-fluoroethyl-5-methoxybenzyl)acetamide ((18)F-FEDAA1106) is a potential PET ligand with highly selective and specific binding to peripheral benzodiazepine receptor (PBR). It has been reported that the regional density of PBR in the brain is increased in several neurodegenerative and psychiatric disorders. Thus, a reliable tracer method for evaluating PBR would be of use clinically and for research. To our knowledge, this is the first study to investigate the (18)F-FEDAA1106 binding to PBR in living human brain by PET. We also aimed to evaluate various analytic methods to quantify the density of PBR. METHODS: PET studies with (18)F-FEDAA1106 were performed on 7 healthy men. Volumes of interest (VOIs) were drawn on PET images. In each VOI, binding potential (BP) was calculated by nonlinear least-squares (NLS) fitting based on the 2-tissue compartment model, and the distribution volume (DV) was also estimated by NLS, Logan plot, and multilinear analysis (MA) methods. To estimate errors in calculation of BP and DV, simulation studies were also performed. RESULTS: The DVs estimated with each of the methods were significantly correlated. There was also significant correlation between BP with NLS and DV with NLS, Logan plot, or MA. But the interindividual differences in the distribution volume of the free and nonspecific binding compartment (K(1)/k(2)) were relatively large. In a simulation study, variation of the DV estimated by Logan plot was relatively small, but it was underestimated as the noise increased. By MA, the bias of DV was smaller, but the variation of DV was larger than by Logan plot. Within a 3% noise level, there was almost no difference between Logan plot and MA in both bias and variation. DVs estimated by both Logan plot and MA were underestimated by 10%-20%. Although the variation of DV was larger by NLS than by Logan plot, it was small enough in the noise level of VOI analysis, and the bias of DV was 0%-2%. CONCLUSION: The simulation studies indicated that NLS is a suitable method for the estimation of (18)F-FEDAA1106 binding to PBRs.

Acetamides↗

PubMed2006

Structural visualization of expert nursing: Diabetes self-management education program.

In the Japanese clinical setting, expert nursing, and at the same time quality and safety assurance, are demanded. To provide nursing service with reliable assurance of nursing quality and safety, structural visualization of the thought, judgment and behavior processes of nursing practice and widespread application through development of IT applied systems are required. We have discussed and developed the structural visualization of programmed care in the field of diabetes self-management education, which is an area of expert nursing care. In this article, we report the programmed care for dietary therapy.

Diabetes Mellitus↗

PubMed2005

Brain magnetic resonance imaging and single photon emission computerized tomography findings in a case of relapsing polychondritis showing cognitive impairment and personality changes.

A 57-year-old female with relapsing polychondritis (RP) showing CNS complications is described with reference to the MRI and SPECT findings. At the age of 56, the patient was diagnosed with RP based on her symptoms, which included bilateral auricular chondritis, nonerosive seronegative inflammatory polyarthritis, and ocular inflammation, as well as vestibular dysfunction. During the course of the disease, she suffered from aseptic meningitis accompanied by delirium, which was resolved by treatment with cyclophosphamide, in addition to prednisolone concurrent with the improvement of her physical condition. After the meningitis improved, she developed a number of cognitive impairments, including time disorientation, agraphia, acalculia, constitutional apraxia, and personality changes. Simultaneously, we observed, via SPECT, a decrease in cerebral blood flow (CBF) in several regions, including the bilateral frontal, lateral temporal, and parietal regions. This is the first study to report on the CNS manifestations of RP with reference to MRI and SPECT findings.

Brain Mapping↗

PubMed2003

A case of delusional disorder, somatic type with remarkable improvement of clinical symptoms and single photon emission computed tomograpy findings following modified electroconvulsive therapy.

A 72-year-old male with delusional disorder, somatic type (DDST), was treated by modified electroconvulsive therapy (mECT). His somatic delusions were completely resolved by mECT. In parallel with the improvement of his clinical symptoms, we observed an improvement of regional cerebral blood flow (rCBF) in the left temporal and parietal lobes shown by the single photon emission computed tomograpy (SPECT). This study appears to support the utility of mECT for somatic delusions in elderly patients and suggests possible association of the dysfunction in the left temporal and parietal lobes with manifestation of the somatic delusion of the patient.

Aged↗