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Biomedical subjects

T Imamura

Publications and source records attributed to T Imamura.

At least 217 records · Page 12Linked to original sources
PubMed1998

Amnestic people with Alzheimer's disease who remembered the Kobe earthquake.

BACKGROUND: Emotional memory is a special category of memory for events arousing strong emotions. To investigate the effects of emotional involvement on memory retention in individuals with Alzheimer's disease we studied peoples' memories of distressing experiences during a devastating earthquake. METHODS: Fifty-one subjects with probable Alzheimer's disease who experienced the Kobe earthquake at home in the greater Kobe area were studied. Memories of the earthquake were assessed 6 and 10 weeks after the disaster in semi-structured interviews, and were compared with memories of a magnetic resonance imaging (MRI) examination given after the earthquake. RESULTS: Forty-four (86.3%) of the subjects remembered the earthquake and 16 (31.4%) of subjects remembered the MRI experience. Factual content of the earthquake was lost in most of the subjects. CONCLUSIONS: Fear reinforces memory retention of an episode in subjects with Alzheimer's disease but does not enhance retention of its context, despite repeated exposure to the information.

Aged↗
PubMed1998

Frontal lobe hypometabolism and depression in Alzheimer's disease.

Depression is common in Alzheimer's disease (AD). Clinicoanatomic studies in focal brain injuries and functional imaging studies both in primary depression and in depression secondary to neurologic diseases have demonstrated involvement of the frontal lobe. Frontal involvement has not been established in the depression of AD. We studied the correlation between focal brain metabolic abnormalities and depression in AD. In 53 patients with probable AD of minimal to moderate disability, we assessed the severity of depression using the Neuropsychiatric Inventory and correlated the depression score with regional cerebral glucose metabolism determined by 18F-fluorodeoxyglucose and PET. Depression was present in 19 patients (36%). The depression score correlated significantly with normalized glucose metabolic rates in the bilateral superior frontal and left anterior cingulate cortices. These results indicated an association between depression and decreased activity in the frontal lobe in AD and support frontal involvement, especially in the left side, in depression, irrespective of disease etiology.

Aged↗
PubMed1998

Regional cerebral glucose metabolism in dementia with Lewy bodies and Alzheimer's disease.

OBJECTIVE: To delineate the features of regional cerebral metabolic rate of glucose (CMRglc) in dementia with Lewy bodies (DLB). METHODS: We compared absolute CMRglc in 12 patients with a clinical diagnosis of DLB, 12 patients with a clinical diagnosis of Alzheimer's disease (AD), and 12 normal volunteers (NC), using 18F-fluorodeoxyglucose (FDG) and PET. The three groups were matched for age and sex, and there were no differences in disease duration or severity of cognitive disturbances between the DLB and AD groups. RESULTS: CMRglc was significantly lower in patients with DLB than in that of NC in most parts of the brain, except the sensorimotor cortices, basal ganglia, thalamus, and pons. Between the DLB and AD groups, there were significant regional CMRglc differences in the medial and lateral occipital lobes. In DLB and AD, the CMRglc reduction patterns were similar, though the global metabolic reduction was larger in DLB, and the occipital CMRglc reduction in DLB could differentiate DLB from AD. The relative occipital CMRglc (normalized to the sensorimotor CMRglc) was a useful measure for the differential diagnosis of DLB from AD. The sensitivity and the specificity were 92% when using the minimal value of the normalized occipital CMRglc in the NC group as the cut-off point. CONCLUSION: These different regional CMRglc reductions substantiate the pathologic, neurochemical, and clinical differences between DLB and AD.

Aged↗
PubMed1998

Medial temporal and whole-brain atrophy in dementia with Lewy bodies: a volumetric MRI study.

OBJECTIVE: Dementia with Lewy bodies (DLB) is emerging as a common cause of degenerative dementia. A recent pathologic study has indicated that the medial temporal lobe in patients with DLB was less atrophic than that in patients with AD. The purpose of this study was to examine whether medial temporal MRI volumetry was useful to differentiate DLB from AD clinically. METHODS: We compared the volumes of the hippocampal formation, amygdaloid complex, and whole brain in 27 patients with probable DLB (based on the criteria of the Consortium on DLB International Workshop), 27 patients with probable AD (based on criteria of the National Institute of Neurological Disease and Stroke/Alzheimer's Disease and Related Disorders Association), and 27 normal elderly subjects using an MRI-based volumetric technique. The three groups were matched for age and sex. Severity of cognitive disturbances represented by their Mini-Mental State Examination score was comparable between the DLB and AD groups. RESULTS: Hippocampal volume (normalized to intracranial volume) in the DLB group was significantly larger than that in the AD group, but significantly smaller than that in the normal control group. There were no significant differences in the amygdala and whole-brain volume between the DLB group and the AD group, but the atrophies of the amygdala and whole brain were more severe in the DLB group than those in the control group. CONCLUSIONS: These findings indicate the usefulness of MRI hippocampal volumetry in clinically discriminating patients with DLB from patients with AD.

Aged↗
PubMed1998

Decrease in circulating and urine adrenomedullin concentrations in stroke-prone spontaneously hypertensive rats.

Adrenomedullin (AM) is a peptide with potent vasodilatory and hypotensive properties. Plasma AM levels in rats with experimentally induced hypertension, such as Dahl salt-sensitive rats and two-kidney, one-clip hypertensive rats, are higher than those in normotensive rats. We previously noted, however, that plasma AM levels in spontaneously hypertensive rats (SHR) are similar to those in Wistar-Kyoto rats. To define the role of AM in rats with severe hypertension, we investigated changes in circulating and tissue AM levels in stroke-prone spontaneously hypertensive rats (SHRSP/Izm). The immunoreactive rat AM levels in plasma, urine, and tissue measured with a sensitive radioimmunoassay, and the AM mRNA levels in various tissues in 15-wk-old SHRSP/Izm were compared with those in age-matched Wistar-Kyoto rats (WKY/Izm). The plasma and urinary AM levels in SHRSP/Izm were significantly lower than those in WKY/Izm [plasma AM, 2.14+/-0.06 (SE) vs. 3.24+/-0.16 fmol/ml, p< 0.001; urinary AM, 16.36+/-3.21 vs. 36.12+/-6.09 fmol/ml, p< 0.01]. A negative correlation was found between the plasma AM level and the systolic blood pressure in both SHRSP/Izm and WKY/Izm. Reverse-phase high-performance liquid chromatography showed that the molecular components of plasma immunoreactive AM in SHRSP/Izm were similar to those in WKY/Izm. Furthermore, tissue AM levels in various organs in SHRSP/Izm were not lower than those in WKY/Izm. In conclusion, low levels of circulating AM may contribute to the maintenance of high blood pressure in 15-wk-old SHRSP/Izm. These low plasma AM levels may be caused by accelerated metabolism of circulating AM in SHRSP/Izm.

Adrenomedullin↗
PubMed1998

MRI monitoring of tarsal navicular stress fracture healing--a case report.

Stress fractures of the tarsal navicular bone are rare injury and assessing its healing is difficult. Tenderness over the tarsal navicular on physical examination is the most reliable sign for assessing fracture healing. However, it is desirable to assess fracture healing with some imaging method. We used serial magnetic resonance imaging (MRI) to assess healing in a patient with a tarsal navicular stress fracture. MRI was useful for the assessment of fracture healing of tarsal navicular stress fracture in our case.

Adolescent↗
PubMed1998

A new reduction technique for a patellar fracture.

We report 4 cases of patellar fracture with skin injury over the patella which were treated operatively immediately after onset with a new reduction technique using Ilizarov pins. This technique made it possible to perform early operative treatment even in the cases with skin injury over the patella which prevents conventional surgical approach.

Adult↗
PubMed1998

[Neuropsychiatric features in Dementia with Lewy bodies and Alzheimer's disease].

BACKGROUND AND PURPOSE: Dementia with Lewy bodies (DLB) is commonly accompanied by neuropsychiatric symptoms. Among them, visual hallucinations are reportedly distinguishing DLB from Alzheimer's disease (AD). However, studies that compared frequency of delusions or depression between in DLB and in AD demonstrated conflicting results. Other neuropsychiatric symptoms including aggression, anxiety, and disinhibition have been rarely explored in DLB. In the present study, in order to elucidate the distinctive neuropsychiatric features in DLB, we analyzed neuropsychiatric symptoms in patients with DLB and with AD using data-based materials. SUBJECTS AND METHODS: Subjects were 15 DLB patients extracted from the Dementia Data Bank in the Hyogo Institute for Aging Brain and Cognitive Disorders, where clinical information of patients with dementia were prospectively assembled with planed, standardized assessments. Both patients groups did not differ in age, education, and duration of illness. The male proportion was significantly greater in the DLB group compared with the AD group (DLB: Male 8, Female 7; AD: Male 27, Female 124, p = 0.008). Patients' neuropsychiatric symptoms were assessed with the Neuropsychiatric Inventory during an interview with a caregiver familiar to the patient's everyday behavior. The Mini-Mental State Examination (MMSE) was used for assessing severity of cognitive impairment. RESULTS: The DLB group had significantly lower MMSE scores compared with AD group (DLB: 16.2 +/- 5.6, AD: 19.3 +/- 4.4, p = 0.013). None of neuropsychiatric symptoms, however, showed a significant relationship with MMSE scores in the DLB group. Hallucination were present in eight (53.3%) of the DLB group. Visual hallucinations were present in seven patients, and both visual and auditory hallucinations in one patient. The frequency of hallucinations (p < 0.0001) and that of visual hallucinations (p < 0.0001) were significantly greater in the DLB group than in the AD group. There was no significant difference in the frequency of auditory hallucinations. Delusions were present in 11 (73.3%) of the DLB group. Misidentification delusions were present in 11 patients, and persecutory delusions were coexisted in 8 patients. The frequency of delusions and that of persecutory delusions in the DLB group did not significantly differ from the AD group. However, the frequency of misidentification delusions was significantly greater in the DLB group than in the AD group (p < 0.0001). No significant difference was noted in the frequency of other neuropsychiatric symptoms. CONCLUSIONS: Hallucinations, especially visual hallucinations, and misidentification delusions are helpful diagnostic features of DLB in differentiating from AD.

Alzheimer Disease↗
PubMed1998

[Preventive measures against hepatitis B virus infection in nursing schools in Japan].

To clarify the use of preventive measures against Hepatitis B Virus infection among nursing students, questionnaires were mailed to 488 nursing schools throughout Japan (including colleges and junior colleges). Two hundred and sixty-eight nursing schools answered our questionnaire. The results are summarized as follows: 1. Eighty percent of the nursing schools that responded, regularly perform the HBs antigen test, and 70% conduct the HBs antibody test. However, only 29% carry out HB vaccinations. 2. Of the 172 schools (71%) that do not actually perform HB vaccinations, only 4% have a HB vaccination plan for the future. 3. The main reasons why the schools do not carry out HB vaccinations are: 1) high cost (48%), 2) low risk of HBV infection among students (34%), 3) the students are thought to be themselves capable of preventing HBV infection (31%). 4. Eighty percent of the nursing schools conduct an orientation program for their nursing students on how to prevent infection before their practical training at school as well as during their practical training at the hospital. 5. Thirty-five percent of the nursing schools have their own "Prevention of HBV Infection Manual", while some of the others use a manual provided by their training hospital. 6. In answer to the question "Do the instructors ask the students to report any potential risk of infection they encounter during their training in the hospital?", 88 approximately 89% of the schools said that they instruct their students to report all injuries involving a needle stick. Other questions relative to various circumstances were also asked. To the question of whether the school requires the students to report any wounds to their fingers or hands, the rate of "yes" answers was only 33%, although this information is essential to prevent avoidable risk. Conclusion In our investigation we found that the HBs antigen and the HBs antibody tests are both performed in a high proportion in nursing schools. Orientation concerning students' training at the hospital to prevent infection is also provided at a high rate. On the other hand, HB vaccinations are not widely performed. Manuals on the prevention of HBV infection are not used at a high proportion either. Also, the reporting system for students encountering any potential risks of infection is insufficient. We think that a more active prevention system for HBV infection should be organized in every nursing school.

Adult↗
PubMed1998

Small round-cell type of malignant peripheral nerve sheath tumor.

Five cases of primitive, small, round-cell tumor that are a type of hitherto unclassified neurogenic sarcoma are described. The tumors were located deep within the soft tissue of the trunks and limbs without association with major nerves. The histologic features consisted mainly of uniform, small, round, tumor cells with scanty cytoplasm. Foci of uniform, short, spindle-shaped tumor cells arranged in whorl-like patterns were observed in some areas. Although the immunoreactivity for the neural markers, Leu-7 and MIC-2, was not marked, cell processes and fragmentous basal laminae, which are ultrastructural neural features, were found in both spindle-shaped and round tumor cells. In four cases, EWS chimeric transcripts were analyzed by reverse-transcription polymerase chain reaction. EWS chimeric mRNA (EWS-FLI-1, EWS-ERG, EWS-E1AF, EWS-ETV1, EWS-FEV) was not detected in any cases. The tumors were not consistent with peripheral primitive neuroectodermal tumor. We propose them as a small round-cell type of MPNST that might differentiate toward the immature neural cells.

Adolescent↗
PubMed1998

CSF spaces in idiopathic normal pressure hydrocephalus: morphology and volumetry.

PURPOSE: Idiopathic normal pressure hydrocephalus (NPH) is an important cause of dementia in the elderly; however, idiopathic NPH is often difficult to differentiate from normal aging and vascular dementias in which brain atrophy with ventricular dilatation (hydrocephalus ex vacuo or central atrophy) is present. To elucidate the distinctive features of the distribution of CSF in idiopathic NPH, we used MR imaging to investigate the morphologic features and volume of the CSF space in patients with idiopathic NPH compared with those with other dementias. METHODS: We assessed the size of four CSF compartments (the ventricle, basal cistern, sylvian space, and suprasylvian subarachnoid space) in 11 shunt-responsive patients with idiopathic NPH by semiquantitative and volumetric analyses of coronal T1-weighted MR images. The results were compared with those in 11 age- and sex-matched patients with Alzheimer disease and in 11 patients with vascular dementia. RESULTS: In patients with idiopathic NPH, the CSF volume was significantly increased in the ventricles and decreased in the superior convexity and medial subarachnoid spaces as compared with patients with other dementias. The sylvian CSF volume in patients with idiopathic NPH was significantly greater than in patients with Alzheimer disease. The volume of the basal cistern was comparable among the three groups. In several patients with idiopathic NPH, focally dilated sulci were observed over the convexity or medial surface of the hemisphere. CONCLUSION: Our results indicate that findings of enlarged basal cisterns and sylvian fissures and of focally dilated sulci support, rather than exclude, the diagnosis of shunt-responsive idiopathic NPH and suggest that this condition is caused by a suprasylvian subarachnoid block.

Aged↗
PubMed1998

Cerebral glucose metabolism in patients with frontotemporal dementia.

UNLABELLED: Frontotemporal dementia (FTD) is a dementia syndrome characterized by peculiar behavioral changes arising from frontotemporal involvement and distinct from Alzheimer's disease (AD). The purpose of this study was to elucidate the specific patterns in cerebral glucose metabolism in patients with FTD and to compare them with the patterns in patients with AD and normal elderly subjects using fluorodeoxyglucose (FDG) and PET. METHODS: Twenty-one patients with a clinical diagnosis of FTD [mean age 67.0 +/- 7.0 yr, Mini Mental State Examination (MMSE) score 18.7 +/- 5.7], 21 age-, sex- and dementia-severity-matched patients with probable AD (mean age 66.9 +/- 7.1 yr, MMSE score 20.2 +/- 5.5) and 21 age- and sex-matched normal control subjects (mean age 66.8 +/- 5.7 yr) were studied. The cerebral metabolic rate for glucose (CMRglc) was measured with FDG and PET. Absolute measures of regional CMRglc were compared among the three groups. One-way ANOVA and the posthoc Tukey HSD test were used for statistical analyses. RESULTS: In the FTD group, CMRglc was preserved only in the left cerebellum, right sensorimotor area and occipital lobes. The CMRglc was significantly lower in the FTD group as opposed to the AD group in the hippocampi, orbital gyri, anterior temporal lobes, anterior cingulate gyri, basal ganglia, thalami, middle and superior frontal gyri and left inferior frontal gyrus. CONCLUSION: Although metabolic abnormality in FTD is predominant in the frontal and anterior temporal lobes and the subcortical structures, it is more widespread than has been previously stressed. These findings document an FTD-specific cerebral involvement and facilitate differential diagnosis of degenerative dementias.

Aged↗
PubMed1997

Distribution of drugs in various tissues in a brain dead man.

We examined the distribution of drugs in a 49-year-old brain-dead man. Our objective was to determine the possibility of diagnosing how and at what point the patient became brain dead. The presence of mepivacaine, pentazocine, lidocaine and thiamylal in various tissues, including seven regions of the brain were confirmed, using gas chromatography/mass spectrometry. Tissue-to-blood concentration ratios of mepivacaine, pentazocine and lidocaine in the brain were higher than these ratios in other tissues, while ratios of thiamylal were lower. Therefore, cerebral blood flow was likely to have ceased between the administration of the former drugs and that of the latter drug, in agreement with clinical records. Among seven regions of the brain, the ratios of the former three drugs were high in occipital and parietal lobes, and were low in the cerebellum and medulla oblongata. On the other hand, the ratios of the latter drug were high in the cerebellum and the medulla oblongata. Therefore, cerebral blood flow presumably ceased first in occipital and parietal lobes, and last in the cerebellum and the medulla oblongata. Based on these results, assessment of concentrations of drugs in human tissues, including various regions of brain is useful to determine the time and progression of brain death.

Analgesics, Opioid↗
PubMed1997

Regional cerebral glucose metabolism in dementia with Lewy bodies and Alzheimer's disease: a comparative study using positron emission tomography.

Regional cerebral metabolic rate of glucose (rCMRglc) was studied in 19 patients with a clinical diagnosis of dementia with Lewy bodies (DLB) and 19 patients with a clinical diagnosis of Alzheimer's disease (AD), using [18F]fluorodeoxyglucose ([18F]FDG) and positron emission tomography (PET). The two groups were matched with age, gender, disease duration and severity of cognitive disturbances. In 'dementia with Lewy bodies' (DLB) patients, when compared with AD patients, significant rCMRglc decreases were distributed in the temporo-parieto-occipital association cortices and the cerebellar hemispheres. In contrast, the medial temporal and cingulate rCMRglc were significantly lower in AD patients than those in DLB patients. These different regional emphases of glucose hypometabolism are consistent with the pathological and neurochemical differences between DLB and AD and explain the different clinical features of the two diseases.

Aged↗
PubMed1997

Smad6 inhibits signalling by the TGF-beta superfamily.

SMAD proteins have been identified as signalling mediators of the TGF-beta superfamily, which is involved in a range of biological activities including cell growth, morphogenesis, development and immune responses. Smad1, Smad2, Smad3 and Smad5 are ligand-specific: Smadl and Smad5 transduce signals from bone morphogenetic proteins, and Smad2 and Smad3 mediate signalling by TGF-beta and activin, whereas Smad4 acts as a common signalling component. For example, Smad2 is phosphorylated by the TGF-beta type I receptor upon ligand binding, forms a heteromer with Smad4, and then translocates into the nucleus where it activates transcription. Here we report the isolation of Smad6 in the mouse. Smad6 is quite different in structure from the other SMAD proteins, and forms stable associations with type I receptors. Smad6 interferes with the phosphorylation of Smad2 and the subsequent heteromerization with Smad4, but does not inhibit the activity of Smad3. Smad6 also inhibits the phosphorylation of Smad1 that is induced by the bone morphogenetic protein type IB receptor. These data indicate that signals of the TGF-beta superfamily are regulated both positively and negatively by members of the SMAD family.

Amino Acid Sequence↗
PubMed1997

Simple and rapid determination of enflurane in human tissues using gas chromatography and gas chromatography-mass spectrometry.

A simple, rapid and reliable method was devised to determine the levels of enflurane in human tissues, using gas chromatography and gas chromatography-mass spectrometry. 1,4-Dioxane was used as an internal standard (I.S.). Enflurane and the I.S. were extracted from 0.25 g of body tissues using an automatic headspace sampler and 1 ml of headspace gas was injected into the gas chromatograph. Enflurane was analyzed qualitatively by gas chromatography-mass spectrometry and quantitatively by gas chromatography with a flame-ionization detector. The calibration curves in all tissues examined were linear in the concentration range 1-100 microg/0.25 g. The lower limit of detection was 200-300 ng/0.25 g. The accuracy and precision of this method were evaluated at two different concentrations, 1 and 20 microg/0.25 g. The coefficient of variation ranged from 3.4-13.4%. We used this method to determine the presence of enflurane in tissues from an autopsied individual who died suddenly during extirpation of a malignant tumor.

Anesthetics, Inhalation↗
PubMed1997

Molecular cloning of rat leukemia inhibitory factor receptor alpha-chain gene and its expression during pregnancy.

Leukemia inhibitory factor (LIF) is a secreted glycoprotein and a pluripotent growth factor that acts on diverse cell systems. LIF transmits its effects via binding to transmembrane receptors, of which both high- and low-affinity forms have been identified. In this study, we analyzed the structure and expression of rat LIF receptor alpha-chain (rLIFR alpha) cDNA. A full-length clone of the cDNA encoding the membrane-bound form of rLIFR alpha protein was prepared by a combination of LA-PCR and 5' RACE using DNA reverse-transcribed from total RNA isolated from the livers of day-12 and day-14 pregnant rats as templates. The nucleotide sequence of a full-length clone was determined and further confirmed by analysis of shorter DNA fragment prepared by PCR using pfu polymerase. The gene for rLIFR alpha encodes a 1093 amino acid residue protein. The rLIFR alpha protein shows a high degree of similarity to mouse and human LIF receptor alpha-chain protein (89% and 76% amino acid sequence identities, respectively). Only one molecular species of mRNA for the rLIFR alpha gene was detected in the liver and placenta. rLIFR alpha was expressed in liver of both non-pregnant and pregnant rats. The level of mRNA for the rLIFR alpha gene in placenta was maximum on day 16 of pregnancy.

Amino Acid Sequence↗