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Biomedical subjects

H Takechi

Publications and source records attributed to H Takechi.

46 records · Page 3Linked to original sources
PubMed1978

Malignant fibrous histiocytoma with skeletal involvement.

Malignant fibrous histiocytoma of soft part is rather common but malignant fibrous histiocytoma of the bone is rarely encountered clinically. Authors present five cases of malignant fibrous histiocytoma with skeletal involvement and discuss their clinical course, x-ray findings and histological features. This tumor has marked tendency for local recurrence and metastasis. Other bone tumors such as giant cell tumor, aneurysmal bone cyst, non ossifying fibroma, osteosarcoma, fibrosarcoma of bone and metastatic cancer can be excluded by several characteristic findings observed in x-rays as well as histopathological features. All information on the patient should be carefully analysed, because it is difficult to decide whether bone involvement is primary or secondary. Four out of five cases definitely originated within the bone.

Bone Neoplasms↗
PubMed1977

Trabecular architecture of the knee joint.

The trabecular architecture of the human knee joint was studied three dimensionally by microradiography. The trabecular arrangement of the two condylar wheels of the femur was divided into five types. The trabeculae are so arranged that both condyles are able to adjust to mechanical compression and rotary movement. In the tibia, each trabecular arrangement has a different mechanical function. The epiphyseal line can be considered a laminated structure interposed between the compressive forces acting from the articular surface and the forces supporting the architecture of the metaphysis. The mechanics and kinematics of the traecular architecture are discussed.

Adult↗
PubMedDate not supplied

A new class of synaptic response involving calcium release in dendritic spines.

In the classical view, transmission of signals across synapses in the mammalian brain involves changes in the membrane potential of the postsynaptic cell. The use of high-resolution cellular imaging has revealed excitatory synapses at which postsynaptic, transient alterations in calcium ion concentration are tightly associated with electrical responses. Here, by investigating the synapse between parallel glutamatergic fibres and Purkinje cells in the mouse cerebellum, we identify a class of postsynaptic responses that consist of transient increases in dendritic Ca2+ concentration but not changes in somatic membrane potential. Our results indicate that these synaptic Ca2+ transients are mediated by activation of metabotropic glutamate-responsive mGluR1-type receptors and require inositol-1,4,5-trisphosphate-mediated Ca2+ release from intradendritic stores. The new type of synaptic response is restricted to postsynaptic microdomains, which range, depending on the frequency of stimulation, from individual spines to small spinodendritic compartments. Thus, the synaptic Ca2+-release signal may be one of the critical cues that determine the input specificity of long-term depression, a well-established form of activity-dependent plasticity at these synapses.

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMedDate not supplied

Local dendritic Ca2+ signaling induces cerebellar long-term depression.

The coordinated activity of large numbers of adjacent parallel fiber synapses elevate calcium concentration locally in small regions of Purkinje cell dendrites. Such activity has also been reported to produce long-term depression of parallel fiber synaptic transmission. We have examined the relationship between these two events by combining patch clamp measurements of parallel fiber synaptic transmission with confocal microscopic imaging of the local calcium signals. We find that patterns of parallel fiber activity capable of evoking long-term depression invariably cause increases in Purkinje cell calcium concentration that are very spatially restricted. These results suggest that one function of the local dendritic calcium signals is to induce long-term depression of parallel fiber synapses.

Animals↗
PubMedDate not supplied

[Artificial legs].

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Artificial Limbs↗