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Biomedical subjects

K Kosaka

Publications and source records attributed to K Kosaka.

At least 289 records · Page 16Linked to original sources
PubMed1986

Appearance of a unique cell type in the fusion sites of facial processes.

The contact sites between the medial and lateral nasal processes during the period of facial formation of the mouse embryo were examined by light and electron microscopy. Characteristic superficial cells were observed at the transitional regions between the surface ectoderms and the nasal epithelia at the end of the isthmus, where the initial contact of the opposing nasal processes took place. At the later stage the contact sites extended to the bottom of the ravine formed by the two nasal processes, where the superficial cells always seemed to bridge the area between the nasal processes. These superficial cells had a large, clear nucleus and abundant cytoplasm as well as the common structural features characteristic of the embryonic cells. These cells were also observed on the surface near the contact site in the presumptive fusion area. These observations suggest that these superficial cells play a critical role in the epithelial adhesion of the medial and lateral nasal processes throughout the fusion.

Animals↗
PubMed1985

GABAergic neurons containing CCK-8-like and/or VIP-like immunoreactivities in the rat hippocampus and dentate gyrus.

The coexistence of cholecystokinin-octapeptide-like (CCK-L) and/or vasoactive-intestinal-polypeptide-like immunoreactive (VIP-LI) materials and glutamate decarboxylase (GAD) was studied in the rat hippocampus and dentate gyrus by means of immunohistochemistry. Consecutive 40-micron-thick sections were incubated in different antisera and those cells which were bisected by the plane of sectioning so as to be included at the paired surfaces of two adjacent sections were identified. The coexistence of the immunoreactivities for these peptides and GAD in the same cell could thus be determined by observing the immunoreactivity of the two halves of the cell, incubated in two different antisera. Almost all of the CCK-LI neurons were also GAD immunoreactive, whereas only about 10% of the GAD-immunoreactive neurons were CCK-LI. The percentages of GAD-immunoreactive neurons which were also immunoreactive for CCK were dependent on the laminar area in which they were found: i.e., 15-20% in the stratum radiatum of the hippocampus, about 10% in the stratum pyramidale, and about 6% in the stratum oriens. In contrast to the CCK-LI neurons, only about 40% of the VIP-LI neurons were identified to be also GAD immunoreactive, which might correspond to only part of the GAD-immunoreactive neurons. Furthermore the coexistence of VIP-LI and CCK-LI materials was recognized in about 10% of the CCK-LI neurons or about 35% of the VIP-LI neurons, indicating that some GABAergic neurons (presumably about 1%) in the rat hippocampus and dentate gyrus may contain both CCK-LI and VIP-LI materials.

Animals↗
PubMed1985

Light and electron microscopy study of fusion of facial prominences. A distinctive type of superficial cells at the contact sites.

The contact site between the medial nasal prominence (MNP) and the lateral nasal prominence (LNP) during the period of primary palate formation in the mouse embryo was examined by light and electron microscopy. Throughout this period, a distinctive type of superficial cell was observed at the contact site. These superficial cells had a large nucleus and abundant cytoplasm as well as structural features characteristic of embryonic cells. At earlier stages, these cells were seen at the transitional region between the surface ectoderm and the epithelia of the nasal pit at the end of the isthmus, where initial contact of opposing MNP and LNP took place. At later stages, these superficial cells appeared to bridge the gap between MNP and LNP at the contact sites, which extended to the bottom of the valley formed by MNP and LNP. These cells were also observed on the surface near the contact sites, that is, the presumptive fusion area. These superficial cells displayed well-developed junctional complexes (intermediate and gap junctions, and desmosomes). Many filaments were observed subjacent to the plasma membranes of these superficial cells, some of which were associated with junctional complexes. These observations suggest that this kind of distinctive superficial cell may play critical roles in the contact of MNP and LNP throughout the fusion process.

Animals↗
PubMed1985

Free amino acids in post-mortem cerebral cortices from patients with Alzheimer-type dementia.

Concentrations of free amino acids were measured in the cerebral cortices of post-mortem brains from 5 histologically verified cases of Alzheimer-type dementia (ATD) and 8 histologically normal controls. The concentration of glutamate in the ATD brains was significantly lower in the superior frontal, orbital, cingulate and inferior temporal cortices when compared with the control brains. The concentrations of taurine and gamma-aminobutyric acid in the ATD brains were significantly lower in the inferior temporal cortex. These findings suggest that amino acid neurons could be involved in ATD.

Aged↗
PubMed1985

EEG activation induced by facilitating position.

The effect of facilitating position of the lower extremity on EEG states was examined through topographical analysis of spectral power for each major frequency band in 8 healthy male subjects. Compared to neutral position, facilitating position of the left or right lower extremity produced significant changes in spectral power, especially in terms of non-specific increase at alpha band (8-12.8 Hz). These results provide further evidence of arousal shift induced by facilitating position, and suggest that EEG topography is a suitable indicator of monitoring the effect of facilitating position.

Adult↗
PubMed1984

Somatostatin and vasoactive intestinal polypeptide in postmortem brains from patients with Alzheimer-type dementia.

Somatostatin- and vasoactive intestinal polypeptide (VIP)-like immunoreactivities (SLI and VLI, respectively) were measured, by radioimmunoassay, in 21 regions of postmortem brains from 7 histologically verified cases of patients with Alzheimer-type dementia (ATD) and 10 histologically normal controls. SLI was significantly reduced in the orbital cortex, hippocampus and putamen of ATD brains. Significant reduction of VLI in the ATD brains was also found in the insular and angulate cortex, which have not previously been examined biochemically for peptides. These results suggest that involvement of not only somotostatin- but also VIP-containing neurons may not be ruled out in ATD brains.

Acetylcholine↗
PubMed1984

Risk factors for worsening to diabetes in subjects with impaired glucose tolerance.

In a 5-12 year follow-up study of 288 subjects with impaired glucose tolerance after a 100-g glucose load, 48 worsened to overt Type 2 (non-insulin-dependent) diabetes with the elevation of fasting blood glucose. The initial level of blood glucose was a major predictor of subsequent worsening to diabetes. In addition, subjects with a lower insulin response to glucose showed a higher incidence of worsening to the disease, irrespective of blood glucose levels. Multivariate analysis indicated that a diminished insulin response and a high maximal body weight index, as well as a high level of fasting and 2-h glucose values at the initial 100-g oral glucose tolerance test were significant independent risk factors for the development of diabetes in Japanese subjects.

Adult↗
PubMed1984

A preliminary study of free amino acids in the postmortem temporal cortex from Alzheimer-type dementia patients.

Concentrations of free amino acids were measured in the temporal cortex of postmortem brains from four histologically verified cases with Alzheimer-type dementia (ATD) and eight histologically normal controls. The concentrations of taurine, glutamate, and gamma-aminobutyric acid, which are all neurotransmitter candidates, were significantly lower in the ATD brains than in the controls. These findings suggest that the involvement of amino acid neurons in ATD cannot be ruled out.

Aged↗
PubMed1984

Changes of biogenic amines and their metabolites in postmortem brains from patients with Alzheimer-type dementia.

Noradrenaline (NA), 3,4-dihydroxyphenylethylamine (dopamine, DA), 5-hydroxytryptamine (serotonin, 5-HT), homovanillic acid (HVA), and 5-hydroxyindoleacetic acid (5-HIAA) were measured in 22 regions of postmortem brains from four histologically verified cases with Alzheimer-type dementia (ATD) and nine histologically normal controls. Compared with the controls, concentrations of 5-HT and 5-HIAA in the ATD brains were significantly reduced in nine regions (superior frontal gyrus, insula, cingulate gyrus, amygdala, putamen, medial and lateral segments of globus pallidus, substantia nigra, lateral nucleus of thalamus) and in eight regions (amygdala, substantia innominata, caudate, putamen, medial and lateral segments of globus pallidus, medial and lateral nuclei of thalamus), respectively. NA concentrations of the ATD brains were significantly reduced in six regions (cingulate gyrus, substantia innominata, putamen, hypothalamus, medial nucleus of thalamus, raphe area). In contrast, significant reductions of DA and HVA concentrations in the ATD brains were found only in putamen and amygdala, respectively. The 5-HIAA/5-HT ratio in the ATD brains decreased significantly in locus coeruleus, while the HVA/DA ratio increased significantly in putamen and medial segment of globus pallidus. These findings suggest that the serotonergic and noradrenergic systems are affected, while the dopaminergic system is relatively unaffected in ATD brains.

Alzheimer Disease↗
PubMed1984

Arousal response induced by postural changes in patients with subacute myelo-optico-neuropathy, "SMON".

In reaction time (RT) experiments, shifts of arousal level induced by postural changes were examined in 10 normal subjects and 10 patients with SMON. Vocal RTs were recorded at neutral position (N) and facilitating position of the left arm (FA) or the left leg (FL). RT-ratios between two positions, FA/N and FL/N, were used as variables to estimate the arousing effect of facilitating positions. Also the correlations between these variables and several clinical signs such as patellar tendon reflex (PTR), sensory disturbance and dysesthesia were calculated. The grade of dysesthesia was strongly related to FL/N. It is assumed that proprioceptive input from the lower extremities causes abnormally high arousal response in patients with dysesthesia.

Adult↗