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Biomedical subjects

K Kadota

Publications and source records attributed to K Kadota.

At least 91 records · Page 5Linked to original sources
PubMed1994

Dopamine D1 and D2 receptors and their signal system present in coated vesicles prepared from bovine striatal tissue.

Coated vesicles (CVs) isolated from bovine striatal tissue were examined to determine whether they are associated with dopamine signal systems consisting of dopamine D1 and D2 receptors, G proteins, and adenylate cyclase. Dopamine receptors in CVs were characterized by a dopamine D1 receptor antagonist, [3H]SCH 23390, and a dopamine D2 receptor antagonist, [3H]-spiroperidol. The bindings of both ligands were specifically saturable and reversible with a dissociation constant (KD) of 0.65 and 0.5 nM, respectively. Dopaminergic antagonists and agonists inhibited the specific bindings of [3H]SCH 23390 and [3H]spiroperidol in a stereoselective and concentration-dependent manner with an appropriate rank order potency for dopamine D1 or D2 receptors. The regulations of the agonist binding by guanyl-5-ylimidodiphosphate were observed. ADP ribosylation of the CVs with [32P]NAD demonstrated predominant labeling of bands of M(r) 47,000-52,000, 42,000-45,000, and 40,000-39,000, which corresponded to the known molecular weights of the alpha subunits of Gs and Gi proteins. The presence of alpha and beta subunits of G proteins in the CVs was also confirmed by immunoblotting assay. Adenylate cyclase activity, which was stimulated by SKF 38393 and inhibited by dopamine D2 receptor agonists, was present in the CVs. These findings suggest that the dopamine D1 and D2 receptors in the CVs couple with adenylate cyclase via Gs/Gi protein.

Adenylyl Cyclases↗
PubMed1994

Surface marker analysis of the vascular and epithelia lesions in cattle with sheep-associated malignant catarrhal fever.

Surface marker analysis of the vascular and epithelial lesions in cattle with sheep associated malignant catarrhal fever (MCF) were done by immunohistochemistry using 7 monoclonal antibodies. MHC class I and II antigens were expressed in the degenerated portion of the vascular walls in addition to infiltrated leukocytes. The major population of mononuclear cells in these lesions were phenotypically macrophages. The other cells had BoCD4 or BoCD8, but rarely gamma delta T cell markers. These results suggest involvement of MHC restriction and macrophages, in addition to autoaggressive cytotoxic T lymphocytes, in the development of MCF vascular lesion.

Animals↗
PubMed1994

Splenic hamartoblastoma in a sow.

Multiple lesions of splenic hamartoblastoma were found incidentally in a 2- to 3-year-old crossbred sow. The predominant cells, characterized by extreme nuclear irregularity and hemidesmosome-like structures, were considered to be derived from reticular cells of the spleen, and demonstrated infiltrative growth. Their cytological atypism and growth pattern suggest that the present lesions are true neoplasms.

Animals↗
PubMed1994

Extra-axial ependymoma--case report.

A 13-year-old boy presented with a very unusual ependymoma extending extra-axially. Computed tomography demonstrated a tumor with a cyst and calcification adjacent to the dura and extending over the right occipital and parietal lobes. The cyst wall and solid tumor were enhanced postcontrast. Magnetic resonance imaging revealed that the solid tumor was isointense on T1-weighted images and a mixed iso- and high-intensity on T2-weighted images. The solid tumor and tissue surrounding the cyst were enhanced markedly by gadolinium-diethylenetriaminepentaacetic acid. Sagittal and coronal images demonstrated a multilocular tumor shadow. Cerebral angiography demonstrated a tumor fed by a posterior branch of the right middle meningeal artery but no feeders from the internal carotid and vertebral arteries. The tumor was removed en bloc. The histological diagnosis was clear cell-type ependymoma.

Adolescent↗
PubMed1994

Hydrocephalus due to villous hypertrophy of the choroid plexus in the lateral ventricles. Case report.

A case is reported of hydrocephalus due to overproduction of cerebrospinal fluid (CSF) caused by villous hypertrophy of the choroid plexus in the lateral ventricles. A 7-year-old girl with mental retardation developed gait disturbance; hydrocephalus and a Dandy-Walker cyst were detected on computerized tomography. She was initially treated with a ventriculoperitoneal shunt; however, shunting failed to control the hydrocephalus. The excessive outflow of CSF suggested choroid plexus abnormality, and magnetic resonance (MR) imaging revealed enlargement of the choroid plexus in both lateral ventricles. The patient was therefore diagnosed as having hydrocephalus induced by overproduction of CSF, which was controlled by resection of the choroid plexus. Histological examination showed the structure typical of normal choroid plexus. This is a rare case of villous hypertrophy of the choroid plexus in which MR imaging assisted in the diagnosis.

Brain Diseases↗
PubMed1994

[Changes in cerebral extracellular pH, cerebral blood flow and intracranial pressure induced by hypercarbic ventilation--assessment as a potential in vivo model of cerebral acidosis].

The effects of acidosis on ischemic brain damage are unclear and probably diverse. To establish an in vivo model of acidosis, the authors assess changes in extracellular brain pH (pHe), CBF and ICP induced by hypercarbic ventilation, and discuss the reliability and short comings of this experimental model. Acidosis was induced by increasing the inspired CO2 concentration in mechanically ventilated rats. pHe was measured with a pH-sensitive electrode implanted into the cortical mantle. The rats were divided into five groups according to the CO2 concentrations inspired: G-1, 0% control; G-2, -5-% CO2; G-3, -10-% CO2; G-4, -20-% CO2; G-5, -25-% CO2. Cortical blood flow was measured using a laser Doppler flowmeter, and ICP was also determined in each of the experimental groups. pHe decreased rapidly after the CO2 supply was turned on and remained almost constant at fixed concentrations of inspired CO2. pHe values diminished as the concentration of inspired CO2 decreased, as follows: G-2, -0.10 +/- 0.03; G-3, -0.31 +/- 0.08; G-4, -0.49 +/- 0.09; G-5, -0.64 +/- 0.10. The changes in pHe almost perfectly paralleled the changes in blood pH. The percentage increase in CBF was more than 200% in the G-2 groups and minimal increases in CBF, probably due to changes in blood pressure, were observed in from G-2 to G-5. Changes in CBF paralleled changes in systemic blood pressure, especially after the CO2 supply was turned off. ICP also rose after increasing the CO2 supply, and the pattern of changes was similar to that of CBF.(ABSTRACT TRUNCATED AT 250 WORDS)

Acidosis, Respiratory↗
PubMed1994

Dynamics of presynaptic endosomes produced during transmitter release.

The movements of the presynaptic endocytotic structures produced during tetanic stimulation at 10 Hz were examined morphometrically and cytochemically in the cat superior cervical ganglion in vivo. The longitudinal profiles of the axon terminal and preterminal area were subdivided into five zones, I-V. Zone I, the area adjacent to the active zone, was assigned a hemicircle with a diameter equivalent to the active zone width (2R). Zones II-IV were defined by subdividing successively the presynaptic and preterminal areas within hemicircles with diameters equivalent to three-, five-, and sevenfold of 2R, respectively. Zone V was composed of the rest of the preterminal profile. The endocytotic structures, macropinocytotic endosomes and coated vesicles, observed in each zone were morphometrically analyzed with the time course of stimulation. The lateral surface of zone II was shown to be the main site for internalization of the terminal surface membrane during transmitter release. A large amount of the plasmalemma of zone II was rapidly retrieved by macropinocytosis to produce early endosomes at an increased rate of about three times that at rest. The population of coated vesicles, few in number at rest, increased to two- to threefold in zones II-V following the stimulation. Cytochemical examinations showed the incorporation of HRP into synaptic vesicles, endosomes and multivesicular bodies. An antibody against synaptophysin labeled the presynaptic endosomes, multivesicular bodies, coated vesicles as well as synaptic vesicles. The results have suggested that a considerable part of these endosomes was transported retrogradely at an increasing rate from zone II to zone V via zones III and IV. On the other hand, synaptophysin was observed to be distributed on the tubular protrusions of the presynaptic endosomes, suggesting the segregation and recycling of a part of synaptic vesicle proteins from the early endosomes in the nerve endings of the cat superior cervical ganglion.

Animals↗
PubMed1994

[Pre-operative autologous blood collection in neurosurgical patients].

Homologous transfusion has been known to cause viral infections and other complications. Recently, autologous transfusion has been adopted widely as a safer and more effective procedure to prevent these complications. The authors report the experiences of 29 patients who had been operated on after preparation of autologous blood. Furthermore, the authors report a study concerning maximum surgical blood order schedule (MSBOS) of these operations. 212 patients operated on between January, 1991 and June, 1993 were used for this study of MSBOS. Although intraoperative transfusion was performed on 14 of 29 patients, the need for homologous transfusion was avoided in 12 of these 14 patients by the use of autologous blood. The frequency of homologous transfusion was reduced significantly after the introduction of pre-operative autologous blood collection in our clinic. The patients' value of hemoglobin fell after the collection of blood but these levels were not so seriously low as to impede the performance of operations. 212 cases of operated patients were divided according to the operative methods and diagnosis for calculation of MSBOS. The results were as follows; Craniotomy and removal of glioma 5u, meningioma 11u, neurinoma 7u, AVM 5u, transsphenoidal surgery 3u, Moyamoya disease 2u and V-P or S-P shunt 0u. Pre-operative autologous blood collection is easy to achieve for scheduled neurosurgical operations, and autologous transfusion is a beneficial procedure which should be used more widely.

Blood Loss, Surgical↗
PubMed1994

[A case of ruptured aneurysm associated with persistent primitive trigeminal artery and metopism].

The authors reported an extremely rare case of ruptured aneurysm associated with persistent primitive trigeminal artery (PTA) and persistent metopic suture (metopism). A 46-year-old female suffered sudden onset of a severe headache with nausea and vomiting on February 24, 1991. She was transferred to Kagoshima Prefectural Oshima hospital from the other clinic on the next day. She complained only of severe headache on admission, and neurological examination revealed no abnormal findings. Plain craniograms disclosed a persistent metopic suture extending from the bregma to the midportion of the frontal bone. Computed tomography demonstrated a mild subarachnoid hemorrhage. The right internal carotid angiograms showed a ruptured aneurysm in the middle cerebral artery. These angiograms also demonstrated PTA originating from the cavernous portion of the internal carotid artery and ending at the mid-portion of the basilar artery. The frequency of angiographic demonstration of persistent primitive trigeminal artery is 0.1 to 0.3%. It is well recognized that approximately 14% of patients with PTA also have intracranial aneurysm. The incidence of persistent metopic suture in adults is 1-10%. After an extensive review of the literature we have concluded that there has been no case report of a ruptured aneurysm associated with PTA and metopism. The authors think that, in this case, the coexistence may be only incidental.

Aneurysm, Ruptured↗
PubMed1994

[Trigeminal neurinoma in the cavernous sinus revealed by intratumoral hemorrhage: a case report].

A case of trigeminal neurinoma located in the left cavernous sinus and revealed by intratumoral hemorrhage is reported. Preoperatively, magnetic resonance imaging provided the accurate localization of the lesion, allowing precise planning of the surgical approach. The neurinoma inside the cavernous sinus wall was removed successfully, and the patient developed no new neurological deficits except for anesthesia in the 1st division of the trigeminal nerve. The characteristic findings of magnetic resonance imaging of the trigeminal neurinoma in the cavernous sinus are reported.

Adult↗
PubMed1993

Rapid recovery of structure and function of the cholinergic synapses in the cat superior cervical ganglion in vivo following stimulation-induced exhaustion.

Cat superior cervical ganglia (SCG) were tetanically stimulated in vivo at 30-100 Hz until neural transmission was exhausted, and then were allowed to rest and recover. Changes in their cholinergic synapses were examined electrophysiologically and morphologically during the time of tetanic stimulation and during recovery. For morphometric analysis the presynaptic terminal was subdivided into two areas: an area directly over the active zone, termed zone-I, (bounded by a hemicircle with a diameter equivalent to the active zone length), and the remaining preterminal area, termed zone-II. In control ganglia before stimulation synaptic vesicle density in zone-I (SVD-I) averaged 90 microns-2 and the number of vesicles actually attached to the active zone (SVA) averaged about 2.5 per single profile of nerve terminal. Upon stimulation, the postganglionic potential immediately began to decline in amplitude and disappeared after 1 min of stimulation. Simultaneously, SVD-I declined to less than 35 microns-2 and SVA declined to less than 1 per section. Thereafter, stimulation was terminated and the ganglion was allowed to rest. Recovery of the postganglionic potential was monitored by stimulation at 1 Hz. The postganglionic potential reached control levels after only 1 min of rest. Likewise, the structural parameters, SVD-I and SVA, also rapidly recovered, reaching control levels after only 30 sec of rest, slightly faster than the postganglionic potential. This illustrates that stimulation-induced fatigue of transmitter output and depletion of synaptic vesicles recover to the control level at a high rate in synapses of the cat SCG with a normal supply of blood. In fact, morphological recovery may be slightly faster than electrophysiological recovery. Mechanisms of vesicle formation and migration to the presynaptic area are discussed in light of these observations.

Acetylcholine↗
PubMed1993

A stable L-arginine-dependent relaxing factor released from cytotoxic-activated macrophages.

It has been known that cytotoxic-activated macrophages release an unstable vasorelaxing substance, nitric oxide. We have found that a more stable relaxing factor is released from those cells. This factor seems to be synthesized from L-arginine. It acts through the activation of soluble guanylate cyclase without affecting membrane potential. It has little charge at nearly neutral pH, and its molecular weight is < 500.

Animals↗
PubMed1993

Eosinophilic meningitis in two cows.

A neurological disorder was noted in 5 cows on a farm. Histopathological examination in 2 of these 5 animals revealed an infiltration of eosinophils with some macrophages in the meninges and around arterioles of the cerebral cortex. The endothelial cells of the reactive blood vessels were swollen. From these observations, the brain lesions were diagnosed as "eosinophilic meningitis". In one case, pulmonary arterioles were also infiltrated with eosinophils and macrophages in a granulomatous tissue. No bacteria, fungi, protozoa, or parasitic worms were detected in the present cases.

Animals↗
PubMed1993

Lymphoplasmacytic lymphoma in a stallion.

Lymphoplasmacytic lymphoma found in a 6-year-old Anglo-Arabian stallion was investigated histologically, immunohistochemically and ultrastructurally. The animal showed a large mediastinal mass and generalized lymph node involvement. The neoplastic cells were in various differentiation stages of small lymphocyte, centrocyte, centroblast, immunoblast and plasma cell. Some neoplastic cells showed positive cytoplasmic reactivity for mu and lambda chains. There were well developed rough endoplasmic reticulum (RER) and Golgi complexes in plasmacytoid cells, and slightly developed RER or a few long strands of RER in medium-sized to large lymphoid cells. These findings suggest that this neoplasm is of B-cell origin.

Animals↗
PubMed1993

[Immunohistochemical analysis of overexpression of c-erbB-2 protein in node-positive breast carcinoma].

We studied the overexpression of c-erbB-2 protein in formalin-fixed, paraffin-embedded tissues from matched primary tumors and metastatic lymph nodes derived from each of 95 breast carcinoma patients. Twenty of 95 primary tumors (21%) exhibited positive membrane staining. Positive staining was also detected in the metastatic lymph nodes from 20 patients. In 19 patients overexpression of c-erbB-2 protein was observed in both primary and metastatic lymph nodes, indicating that there is a significant correlation between c-erbB-2 protein overexpression of primary and secondary metastatic lesion. Overexpression of the c-erbB-2 protein was observed at almost the same frequency regardless of clinical stage. The c-erbB-2 protein overexpression was associated with an absence of estrogen and progesterone receptors. Furthermore the overall survival and disease-free survival were reduced, although not significantly, in the patients with c-erbB-2 protein overexpression. Multivariate analysis indicated that overexpression of c-erbB-2 protein was a significant predictor of early relapse for node-positive patients. These results suggest that overexpression of the c-erbB-2 protein plays a role not only in an early stage but also in a metastatic stage in a certain patient subpopulation with breast carcinoma, and that c-erbB-2 protein overexpression analyzed by immunohistochemical techniques is of clinical significance in these patients.

Analysis of Variance↗
PubMed1992

Reduction of glutamate release and protection against ischemic brain damage by BW 1003C87.

BW 1003C87, 5-(2,3,5-trichlorophenyl)-2,4-diaminopyrimidine ethane sulphonic acid, has been tested for its in vitro and in vivo effects on glutamate release in rat brain tissue, and for its cerebro-protective action in two rodent models of cerebral ischemia. In rat brain slices the release of glutamate evoked by veratrine is inhibited by BW 1003C87 (IC50 = 1.6 microM). In anaesthetised rats with microdialysis probes implanted in the dorsal hippocampus the increase in extracellular glutamate evoked by veratrine is markedly reduced by co-infusion of BW 1003C87, 100 microM. In anaesthetised rats with microdialysis probes implanted in the cortex and the caudate nucleus ipsilateral to a middle cerebral artery (MCA) occlusion the increase in dialysate glutamate concentration seen in the first 2 h following MCA occlusion is markedly attenuated by the prior administration of BW 1003C87, 20 mg/kg i.v. In rats subjected to 10 min of bilateral common carotid artery occlusion the loss of CA1 pyramidal neurons (assessed 7 days later) is reduced by administration of BW 1003C87 (20 mg/kg i.v., at the time of ischemia and 4 h later). The volume of cortex showing infarction 72 h after unilateral MCA occlusion is reduced by treatment with BW 1003C87 (20 mg/kg, i.v., beginning 5 min after occlusion). Inhibition of glutamate release may provide a therapeutic approach in cerebral ischemia as well as in epilepsy.

Animals↗
PubMed1992

A case of bovine sex cord tumour with annular tubules.

A case of sex cord tumour with annular tubules was found in the right ovary of a 17-month-old Holstein cow. The tumour was characterized by tubules encircling hyaline bodies, which were composed of concentric lamellae of basal lamina. Several irregular tubular structures and a small component of granulosa cell differentiation were seen. Immunohistochemically, the neoplastic cells stained positively for oestradiol or testosterone.

Animals↗