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Biomedical subjects

T Kawarabayashi

Publications and source records attributed to T Kawarabayashi.

At least 19 recordsLinked to original sources
PubMed1992

Ultrastructural characterization of cerebellar diffuse plaques in Alzheimer's disease.

We examined the ultrastructural localization of beta/A4 protein in cerebellar diffuse plaques (DP) in three Alzheimer's disease brains by the indirect immunoperoxidase technique. Intense immunoreaction products were scattered in the DP; they were strongly suggested to be located between small cell processes. Reaction products were dot-like and/or amorphous, and occasionally fibrillar. Adjacent semithin sections of regions immunoreactive for beta/A4 protein revealed only very small amounts of amyloid fibrils between cell processes and/or small numbers of degenerating neurites. The small degenerating neurites which appeared in most DP lacked paired helical filaments (PHF) and neurofilaments (NF). These findings suggest that the majority of the beta/A4-immunoreactive substance in cerebellar DP is non-fibrillar pre-amyloid found between cell processes and barely detectable by routine electron microscopy.

Aged↗
PubMed1991

Expression of APP in the early stage of brain damage.

We immunocytochemically studied the expression of various epitopes of amyloid beta/A4 protein precursor (APP) after brain damage by kainic acid injection. After 3 h, APP695 rapidly accumulated in dystrophic neurites near the damaged site. After 3 days, APP with Kunitz-type protease inhibitor domain was expressed in reactive astrocytes in the lesion and ipsilateral hippocampus. APP rapidly accumulated in dystrophic neurites, and different types of APP were expressed in different cell types in the damaged brain.

Amyloid beta-Peptides↗
PubMed1991

Amyloid beta/A4 protein precursor is widely distributed in both the central and peripheral nervous systems of the mouse.

We studied the immunocytochemical distribution of amyloid beta/A 4 protein precursor (APP) in both the central and peripheral nervous tissues of the mouse. We used two different antisera against the synthetic peptides corresponding to the carboxyl- and the amino-terminal regions of APP, which are common to all isoforms of APP (APP695, APP714, APP751 and APP770). Both antisera recognized the same 106-122 kDa proteins from the mouse brain on immunoblotting. Immunocytochemically, in cortical and subcortical areas, reactivities of both antisera were located in neurons of all sizes. Immunoreactive neurons were widely distributed showing no particular pattern. Various neuron types in the spinal cord were also immunoreactive. In the peripheral nervous system, ganglion cells and their processes showed immunostaining. Immunoreactivity was also seen in the astrocytes, oligodendroglia and ependymal cells widely distributed in the brain and spinal cord, mantle cells in the ganglia, and Schwann cells in peripheral nerves. These results indicated that the full length of APP is distributed in almost all neurons and some glial cells in the mouse central and peripheral nervous systems.

Amyloid beta-Protein Precursor↗
PubMed1991

Subpial beta/A4 amyloid deposition occurs between astroglial processes in Alzheimer-type dementia.

We examined the ultrastructure of subpial beta/A4 amyloid deposits in the brains of patients with Alzheimer-type dementia. A few amyloid fibrils were found between thick astroglial processes (glia limitans). We also examined the ultrastructural localization of beta/A4 protein by the indirect immunoperoxidase technique. Electron-dense immunoreactive products scattered sporadically in the subpial areas were observed between astroglial processes. The labeling was fibrillar and/or amorphous. Subpial beta/A4 deposition may occur between astroglial processes as amorphous pre-amyloid and amyloid fibrils.

Aged↗
PubMed1991

Extracellular neurofibrillary tangles associated with degenerating neurites and neuropil threads in Alzheimer-type dementia.

We examined the cellular components of extracellular neurofibrillary tangles (E-NFT) in the hippocampal areas in cases with Alzheimer-type dementia. Immunohistochemically, the E-NFT were labeled for the C terminus of tau and glial fibrillary acidic protein. Moreover, the majority of the E-NFT was associated with intensely argyrophilic rods and with tau- and ubiquitin-immunoreactive dots. Ultrastructurally, the E-NFT consisted mainly of extracellular paired helical filaments (PHF) and astroglial processes. The extracellular PHF tended to be straighter and thinner. One third of the E-NFT was associated with small degenerating neurites containing many dense bodies and with neuropil threads containing PHF. These findings suggested that extracellular PHF promote both intense astroglial reaction and neuritic alteration, and that the E-NFT are continuously changing their morphology.

Aged↗
PubMed1991

Light and electron microscopic and immunohistochemical observations of the Onuf's nucleus of amyotrophic lateral sclerosis.

We examined the Onufrowicz nucleus (Onuf's nucleus) of ten sporadic amyotrophic lateral sclerosis (ALS) patients with light and electron microscopic and immunohistochemical methods. Neurons in the Onuf's nucleus of ALS patients were better preserved than those in anterior horn cells. However, some showed morphological changes in the nucleus, namely, central chromatolytic changes, Bunina bodies, ubiquitin-positive filaments and spheroids. The Onuf's neurons of ALS patients showed more argentophilia than those of non-ALS patients. Electron microscopic observations revealed that neurofilaments were relatively more numerous in the Onuf's neurons of ALS patients. Bunina bodies and degenerated neurites were also seen in the Onuf's nucleus. In conclusion, the Onuf's nucleus in sporadic ALS patients showed some morphological changes similar to those noted in anterior horn cells.

Aged↗
PubMed1991

Qualitative evaluation of uterine contractions recorded by a double guard-ring tocodynamometer.

Qualitative characteristics of uterine contractions in various labors were evaluated by a double guard-ring tocodynamometer, according to the percentages of concurrent and synchronous contractions of two contraction curves when compared with overall contractile activity. For term and preterm labors, percentages of both concurrent and synchronous contractions were significantly higher than those of Braxton Hicks contractions; however, the concurrent and synchronous percentages of preterm labor were lower than those of term labor. Synchronous percentage in groups under maintenance therapy or active treatment in preterm labor were nearly the same; however, the percent concurrent under maintenance therapy was significantly lower than that during active treatment. Both concurrent and synchronous percentages were significantly higher during the active phase of labor than those during the latent phase. The percentages in the latent and active phases of spontaneous contractions were nearly the same; however, they increased significantly during the active phase of augmented contractions, as compared with the latent phase. When the percentages of concurrent and synchronous contractions at each cervical dilatation were retrospectively examined, both values increased significantly between 5 and 6 cm of cervical dilatation. The results suggest that this method can provide important information for understanding the quality of the contraction if attention is paid to the percentages of concurrent and synchronous contractions of two contraction curves and will aid in determining whether oxytocin or tocolysis should be given in term or preterm labor.

Cardiotocography↗
PubMed1991

Intracellular calcium of longitudinal muscles isolated from pregnant rat myometrium.

Longitudinal muscle cells were successfully isolated from pregnant rat myometrium (21 days of gestation) with more than a 95% survival rate. The approximate size of relaxed cells was 232.2 +/- 74 microns in length and 16.2 +/- 7.0 microns in width. Using the fluorescent indicator Fura-2, the concentration of intracellular free calcium ([Ca2+]i) in resting state cells was calculated to be 116 +/- 18.5 nM. The isolated cells responded well to K+, acetylcholine and oxytocin in terms of contraction as well as the increase in [Ca2+]i. The increase in [Ca2+]i induced by acetylcholine and K+ appeared to be mainly due to an influx of extracellular Ca2+. On the other hand, the oxytocin-induced increase in [Ca2+]i was mainly due to a release of Ca2+ from intracellular storage sites in the isolated cells. Isolated longitudinal muscle cells can serve as a useful tool in establishing the relationship between [Ca2+]i and regulation of the uterine contraction at the final stage of pregnancy.

Acetylcholine↗
PubMed1991

Relationship between changes in contraction and cyclic AMP contents under long-term application of ritodrine in pregnant rat myometrium.

The relationship between contraction changes and cAMP production under long-term application of ritodrine was investigated using longitudinal muscle strips of pregnant (Day 21) rat uterus. Cellular cAMP gradually increased up to 20 min, then decreased to the control level and fluctuated after 90 min in the presence of 1.5 x 10(-7) M ritodrine. When the dose was raised to 3.1 x 10(-4) M, cAMP contents markedly increased. However, it then decreased after 30 min and reached the control level after 180 min. To clarify the actual relationship between the changes in spontaneous contraction and cAMP contents of the same muscle strips, the strips were obtained during control contraction, suppression by 1.5 x 10(-7) M ritodrine and reactivation after suppression in the presence of the drug. Consequently, the cAMP content of reactivated muscle was significantly lower than that of suppressed muscle (p less than 0.01), however it was still higher than the control (p less than 0.05). It is speculated that the reactivation of spontaneous contractions might not depend solely on the cellular cAMP level, and that another activating mechanism, such as changes in ion permeability, might be involved in this type of desensitization phenomenon.

Animals↗
PubMed1991

Pheochromocytoma with electrocardiographic change mimicking angina pectoris, and cyclic change in direct arterial pressure--a case report.

A forty-two-year-old man was admitted because of chest pain. Electrocardiograms at admission showed horizontal ST depression in leads, II, III, aVF, V4, V5, and V6. Direct blood pressure monitoring revealed cyclic change between 160/100 mmHg and 70/50 mmHg and heart rate between 80/sec and 120/sec at fifteen minute intervals. The plasma norepinephrine and epinephrine concentrations were elevated during the episodes of hypertension. Pheochromocytoma was found in the right adrenal gland. These cyclic changes in blood pressure and heart rate are an aid for diagnosis.

Adrenal Gland Neoplasms↗
PubMed1990

The amyloid beta-protein precursor is localized in smooth muscle cells of leptomeningeal vessels.

We examined leptomeningeal vessels using 2 different antisera which recognized both terminal ends of amyloid beta-protein precursor (APP). Both antisera recognized a 120-kDa protein from leptomeningeal vessels. Immunocytochemistry showed that APP was localized in the smooth muscle cells of leptomeningeal vessels. These results indicated that the smooth muscle cells of leptomeningeal vessels contained full-length native APP, and that the cerebrovascular amyloid in the leptomeningeal vessels was derived from this APP.

Aged↗
PubMed1990

Amyloid beta-protein precursor accumulates in dystrophic neurites of senile plaques in Alzheimer-type dementia.

We raised two rabbit antisera against synthetic peptides corresponding to the carboxyl- and amino-terminal regions of the predicted amyloid beta-protein precursor (APP). Both antisera recognized the same 106-135 kDa proteins of human brain extract by immunoblot analysis. Immunocytochemical studies showed that these antisera both reacted with the same dystrophic neurites within the senile plaques of Alzheimer brains. These results indicated that APP accumulated in the dystrophic neurites of the senile plaques.

Aged↗
PubMed1990

Effect of methylergometrine maleate (methergin) on electrical and mechanical activities of pregnant human myometrium.

The effect of methylergometrine maleate (methergin) on electrical and mechanical activities of pregnant human isthmic myometrium was examined. Methergin (10(-8)-10(-6) g/ml) enhanced plateau potential and contraction, however, the effects were not prominent. Plateau potential and contraction were also potentiated after pretreatment with 10(-7) g/ml phentolamine (alpha-blocker), however 10(-7) g/ml methergin further increased these effects. It is suggested that methergin might potentiate contractions by changing the pattern of action potentials and not by alpha-adrenoceptor.

Action Potentials↗
PubMed1990

Alzheimer amyloid beta-protein precursor in sperm development.

We prepared antisera to both the N and C termini of amyloid beta-protein precursor (APP). Both antisera labeled 110 to 140 kd proteins from rat testis by immunoblotting. Northern blot analysis using oligonucleotide probes complementary to respective APPs showed that APPs expressed in rat testis contained Kunitz-type protease inhibitor domains. Immunocytochemically brain APP was localized in neurons and their processes. During sperm formation, APPs labeled by both antisera were localized only in acrosome and the growing tail of spermatids in the seminiferous tubules. This shows that APPs appear only in particular phases of spermatogenesis, that is, in the morphologic change phase from spermatid to mature sperm. Amyloid beta-protein precursors in testis may play a role in cellular differentiation or morphologic change.

Amyloid beta-Peptides↗
PubMed1990

Modification by magnesium of the excitatory effect of oxytocin in electrical and mechanical activities of pregnant human myometrium.

The modification by magnesium of the excitatory effect of oxytocin (10(-5)-10(-2) U/mL) on electrical and mechanical activities of pregnant human myometrium was examined. The excitatory effect of oxytocin was enhanced by external magnesium, and the dose-response curve between oxytocin and relative tension in the presence of 118 mM potassium in tiny muscle strips shifted to the left with increases in magnesium from 0 to 2.4 mM. Oxytocin potentiates spontaneous contractions by enhancing the plateau part of action potentials, and the plateau potential induced in 2.4-mM magnesium was larger than that in magnesium-free solution. In potassium contracture experiments, the muscle contraction was potentiated in accordance with the concentration of preloaded magnesium when 10(-3) U/mL oxytocin was added at the tonic phase. These results suggest that magnesium might primarily potentiate the excitatory effect of oxytocin in electrical and mechanical activities of pregnant human myometrium at superficial sites of the plasma membrane, allowing the possibility of its intracellular action.

Action Potentials↗