Biomedical subjects

I Ishihara

Publications and source records attributed to I Ishihara.

At least 19 recordsLinked to original sources

PubMed2003

Synaptic loss following depletion of noradrenaline and/or serotonin in the rat visual cortex: a quantitative electron microscopic study.

Biogenic amines have a trophic-like role for the formation and the maintenance of synapses in the CNS. We examined the changes in the number of synaptic profiles in the developing and adult rat visual cortex following selective depletion of noradrenaline and/or serotonin. By the drug-induced decreases in levels of noradrenaline or serotonin between 1 and 2 weeks after birth, the number of synaptic profiles was decreased by 29-55% compared with that of control animals. The magnitude of reduction in the number of synaptic profiles was virtually the same following simultaneous depletion of both noradrenaline and serotonin compared with the depletion of noradrenaline or serotonin alone. Later in the developmental period, the function of noradrenaline and serotonin in facilitating synapse formation and maintenance became less prominent than that in younger animals. In the control animals, the number of axosomatic synapses was the highest at around 2 weeks after birth, and decreased with development. The number of axodendritic synapses was the highest between 2 and 7 weeks after birth, and decreased to 50% at 11 weeks after birth. These data demonstrate that synapses in the rat visual cortex are overproduced during the early developmental period. We suggest that both serotonin and noradrenaline are necessary for synapse formation during the early stages of development of the rat visual cortex.

Aging↗

PubMed2001

[Study of environmental factors for care of demented elderly men].

Men interact with the environment, which sometimes leads them into distressful conditions. This stressful stimulation can induce neurodegeneration and hippocampal atrophy by increasing the glucocorticoid level. Especially, the elderly population is very vulnerable to exposure to the increased glucocorticoid due to environmental stress that results in accelerating the aging process. On the other hand, enriched physical and human environments may help to maintain their cognitive function in spite of aging. For example, aged healthy volunteers with a lower glucocorticoid level caused by avoiding distressful conditions were able to maintain large volumes of hippocampus and a better short-term memory. The purpose of this study was to investigate whether better residency for the elderly men who have a mild type of senile dementia can maintain their mental abilities. We observed and videotaped behaviors of demented elderly men who lived in either a group home or a traditional type of nursing home while they were participating in their daily activities. We made our own inventories which measured the total mental abilities, such as degrees of social interaction, degrees of motivation for participation in daily activities, degrees of independence, and degrees of facial expression, then analyzed the data with these inventories in order to compare the behaviors of the two groups. The result did not show any significant differences in the levels of mental abilities, the degrees of motivation for participation in daily activities and independence between the two groups. However, regarding social interaction, the elderly men who live in the group home exhibited a more approaching behavior toward an unfamiliar person than those who lived in the traditional nursing home.

Activities of Daily Living↗

PubMed2001

Syk protein-tyrosine kinase is involved in neuron-like differentiation of embryonal carcinoma P19 cells.

Syk has been implicated in activated immunoreceptors to downstream signaling events in hematopoietic cells. Here we report that Syk is expressed in neuron-like cells and involved in neuron-like differentiation of embryonal carcinoma P19 cells. Immunoblot, RT-PCR, and Northern analysis indicated that Syk is expressed in mouse brain, PC12 and P19 cells. In addition, Syk was found to be tyrosine phosphorylated during neuron-like differentiation of P19 cells. Furthermore, adenovirus-mediated overexpression of Syk induced supernumerary neurite formation and extracellular signal-regulated kinase (ERK) activation in P19 cells. These results suggest that Syk plays an important role in signaling steps leading to ERK activation in P19 cells.

Adenoviridae↗

PubMed2000

Activation of calpain precedes morphological alterations during hydrogen peroxide-induced apoptosis in neuronally differentiated mouse embryonal carcinoma P19 cell line.

In order to reveal neurodegeneration elicited by reactive oxygen intermediates (ROI), neuronally differentiated cells from mouse embryonal carcinoma P19 cell line were exposed to hydrogen peroxide (H2O2). Enhanced protein-phosphorylation on tyrosine residues was detectable within 5 min of exposure to H2O2, and gradual rises in intracellular free Ca2+ level and in calpain activity were observed. Furthermore, H2O2 stimulation of differentiated P19 cells for 24 h resulted in morphological alterations in somas as well as neurites. Also, within 6 h of H2O2 treatment DNA fragmentation has been detected. Taken together, these results suggest that oxidative stress induces degradation of cytoskeletal proteins presumably resulting from increased intracellular Ca2+ concentration and subsequent activation of calpain.

Animals↗

PubMed1999

Symptom classification of schizophrenia changes with the duration of illness.

Our starting hypothesis was that schizophrenic symptomatology changes over time. This hypothesis explains conflicting reports on schizophrenic symptom structures as a consequence of different durations of illness in the samples studied to date. Therefore a sample of 258 schizophrenic in-patients (with ICD-10 diagnoses F20) was categorized according to illness duration. A factor analysis was performed on the 8 items of the Manchester Scale for three subgroups (duration < 10 years, 10> or =20 years and > or = 20 years). For those patients whose illness duration was less than 10 years, 'formal thought disorder' was not related to any other mental state, whereas for those whose duration was 10 years or longer, it was correlated with 'negative symptoms'. In the < 10 years group, 'anxiety and depression syndrome' and 'positive symptoms' formed one complex, but these symptoms were separated into two distinct syndromes in the > or = 20 years group. Thus we were able to demonstrate that the classification of symptoms changes with increasing duration of illness.

Adolescent↗

PubMed1999

Criteria defining refractory schizophrenia.

To date there has been no agreement with regard to the criteria that define refractory schizophrenia. In this study, we intended to clarify the criteria which psychiatrists use to judge schizophrenic patients as being refractory in Japan. Based on 258 schizophrenic in-patients (ICD-10) and their likelihood of discharge, level of psychosocial functioning, mental state and use of medication, the common features of patients who are viewed as non-dischargeable because of their severe mental state, compared to those of dischargeable patients, were extracted and used as the criteria. The criteria proposed necessitate (i) diagnosis of schizophrenia by standard operational criteria, (ii) continuous hospitalization for at least the past 2 years, (iii) a level of psychosocial functioning of < or = 40 as measured by the Global Assessment Scale, and (iv) an intensity score of 'marked' or 'severe' on at least three of the six Manchester Scale items (flattened affect, psychomotor retardation, delusions, hallucinations, incoherence of speech and poverty of speech).

Adult↗

PubMed1999

[Differential diagnosis of schizophrenic symptoms complicated with brain anomalies including bilateral temporal arachnoid cysts by eye mark recorder and PET: a case study].

Bilateral temporal arachnoid cysts and other intracranial congenital lesions including a moderately large left temporal arachnoid cyst accompanied by remarkable dysplasia of the temporal lobe in particular were discovered by chance during computerized axial tomography of a 26-year-old Japanese male who had been diagnosed as schizophrenia approximately 10 years earlier. A detailed re-assessment revealed no other organic symptoms or signs. His symptoms and clinical course met the DSM-IV criteria for schizophrenia, disorganized type. Based on his symptoms, positron emission tomography (PET) and the eye-movement recording test developed by Kojima et al. were performed. In addition, psychological tests including WAIS, Rorschach Test, and Wechsler's Memory Test were administered for further differential diagnosis. PET using continuous inhalation of oxygen 15-gas revealed a regional decrease in CBF and CMRO2 in the superior medial frontal lobe including the anterior cingulate gylus, findings sometimes associated with schizophrenia. However, no abnormal findings were noted around the arachnoid cysts. In the eye-movement recording test, several parameters including the responsive search score (RSS) were about the same level as that commonly observed in schizophrenics and are classified as schizophrenia by discrimination analysis. The psychological tests offered no reason to doubt the diagnosis of schizophrenia. Thus, the patient was diagnosed as schizophrenia with arachnoid cysts and other intracranial lesions. The way of diagnosis we used here might bring forth a breakthrough in schizophrenia research by differentiating schizophrenia from the other organic brain diseases.

Adult↗

PubMed1984