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K Kitamura

Publications and source records attributed to K Kitamura.

At least 1,117 records · Page 62Linked to original sources
PubMed1985

Altered metabolic profiles of valproic acid in a patient with Reye's syndrome.

Urinary valproate metabolite and endogenous organic acid profiles in a 6-yr-old girl with Reye's syndrome were investigated by means of gas chromatography-mass spectrometry. 2-n-Propyl-3-oxovaleric acid, normally the major metabolite of valproate in man, was undetectable, while 2-n-propylglutaric acid, the end product via omega-oxidation was markedly increased. Polyunsaturated valproate was not found. Valproate-glucuronide was still found as the major metabolite. The clinical findings coupled with a greatly increased excretion of lactate and adipate was compatible with Reye's syndrome. Ketone bodies were not detectable. This case study shows that Reye's syndrome causes altered valproate metabolism, consistent with the defective mitochondrial beta-oxidation of medium chain fatty acids, and suggests that valproic acid should not be used in the treatment of seizures in patients with this syndrome.

Biotransformation↗
PubMed1985

Virus-like particles in human vestibular ganglion cells.

We found intracytoplasmic aggregates of virus-like particles in human vestibular ganglion cells. These particles were always observed in the peripheral area of the cytoplasm. Morphological characteristics of the cytoplasm are similar to those of other ganglion cells. The inclusion bodies are round and measure about 1.7 micron in maximum diameter. They consist of a porous convoluted dense material and virus-like particles. The overall diameter of 118 randomly selected particles varies from 36 nm to 73 nm, and the mean value is 53 nm. Most of the particles are spherical while a few possess a hexagonal or semicircular profile. The particles exhibit a double external membrane or vesiculated external layer. Most of the particles are empty. There are, however, some particles which show vesicular structures in their content. Although our present data are insufficient to determine these particles as viral, their hexagonal shape and size are similar to true virus. With these data in mind, we suggest that these particles might be a dormant form of virus and may possibly produce infectious disease in the inner ear.

Aged↗
PubMed1985

The different mechanisms of action of nicorandil and adenosine triphosphate on potassium channels of circular smooth muscle of the guinea-pig small intestine.

Nicorandil (10 mumol/l-0.3 mmol/l) and ATP (1 mumol/l - 0.1 mmol/l) hyperpolarized the membrane of circular smooth muscle of the guinea-pig small intestine and increased conductance of the membrane probably to K ions as estimated by the effect on the current-voltage relationship. In the presence of a maximally hyperpolarizing concentration of nicorandil (0.1 mmol/l), ATP produced a further hyperpolarization of 5 mV. The ATP-induced but not the nicorandil-induced hyperpolarization required the presence of Ca in the medium, and the ATP-induced hyperpolarization was blocked by apamin treatment (1 nmol/l) or by MnCl2 (1.3 mmol/l). On the other hand, both hyperpolarization responses were blocked by the local anaesthetics procaine (0.1 - 1 mmol/l), lidocaine (0.1 - 1 mmol/l) or cocaine (0.3 - 1 mmol/l), with different potencies. Field stimulation of smooth muscle of the small intestine produced inhibitory junction potentials (i.j.p.s) and these were inhibited by apamin (10 nmol/l - 100 nmol/l). In the presence of ATP, the amplitude of the i.j.p.s was markedly reduced, but in the presence of nicorandil the amplitude was only slightly reduced, consistent with the same increase in ionic conductance and hyperpolarization of the membrane. These results indicate that ATP and nicorandil hyperpolarize the membrane by activating different K-channels, i.e. Ca dependent and Ca insensitive K channels, respectively. As assessed from the effects of local anaesthetics and the membrane properties, the circular muscle may also possess other K channels different from the ATP and nicorandil sensitive K channels.

Adenosine Triphosphate↗
PubMed1985

Two Ca-dependent K-channels classified by the application of tetraethylammonium distribute to smooth muscle membranes of the rabbit portal vein.

Dispersed single smooth muscle cells of rabbit portal vein were prepared by treatment with collagenase and trypsin. The muscle cells were 100-300 micron in length, 5-10 micron in maximum width and cylindrical in shape. In inside-out membrane patches, two different amplitudes of ionic currents were recorded, and these single channel conductances were 273 pS (KL-channel) and 92 pS (KS-channel), when both sides of the membrane were exposed to 142 mM K+ solution. The channel conductances depended on concentrations of K+ on both sides of the membrane. When K+ were replaced with Na+ or Tris+, these single-channel currents were abolished. When the concentration of Ca2+ inside the membrane was greater than 10(-7) M, the channel activity was enhanced but there was enhancement when Ca2+ was applied to the extracellular membrane surface, in concentrations ranging between 10(-9) and 10(-3) M. During application of tetraethylammonium (TEA+; 1-10 mM) to the intracellular membrane surface, amplitudes of the single-channel current of both types of the K-channel were not modified. By contrast application of TEA+ (0.1-1 mM) to the extracellular membrane surface, reduced the amplitudes of the current and increased noise levels during the open-state of the KL-channels, but did not have such an effect on the KS-channel. We conclude that there are at least two different Ca-dependent K-channels distributed on the smooth muscle membrane of the rabbit portal vein. TEA+ applied to the extracellular membrane surface blocks activation of the KL-channel, but not that of the KS-channel.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Microsurgical anatomy around the origin of the ophthalmic artery with reference to contralateral pterional surgical approach to the carotid-ophthalmic aneurysm.

The supraclinoid segments of the internal carotid artery (ICA) and their surrounding structures were examined under magnification in 25 adult cadavers. Attention was paid to anatomical variations and relationships concerning ipsilateral and contralateral pterional microsurgical approaches to these regions, especially to the origin of the ophthalmic artery. Eighty-four percent of the ophthalmic arteries arose from the supraclinoid segment of the ICA. In the ipsilateral pterional approach, mobilization of the ipsilateral optic nerve was required to see the origin of the ipsilateral ophthalmic artery and the medial aspect of the proximal portion of the supraclinoid segment of the ICA. In the contralateral pterional approach, on the other hand, these areas on the contralateral side could be identified under the optic nerve with minimal or without retraction of the contralateral optic nerve. This was because 71% of the ophthalmic arteries arose from the supero-medial aspect of the ICA, and because there was nothing to intercept the view of the medial aspect of the ICA under the optic nerve. This study supports the usefulness of the contralateral pterional approach to the origin of the ophthalmic artery and the medial aspect of the supraclinoid segment of the ICA. This approach could be useful in certain cases of carotid-ophthalmic aneurysm. The authors' experience with the contralateral pterional approach to carotid-ophthalmic aneurysms is also described.

Carotid Artery, Internal↗
PubMed1985

Studies on neurotransmitter markers and neuronal cell density in the cerebellar system in olivopontocerebellar atrophy and cortical cerebellar atrophy.

Glutamate, aspartate and gamma-aminobutyrate (GABA) concentrations and choline acetyltransferase (ChAT) activity were measured in postmortem cerebellar cortical areas and brainstem nuclei of 10 normal controls, 5 patients of olivopontocerebellar atrophy (OPCA) with multiple system atrophy (MSA) and 2 patients of cortical cerebellar atrophy (CCA). In addition, the neuronal cell density in the cerebellar cortex and the brainstem nuclei was determined, and the correlation between neurotransmitter markers and the neuronal cell densities were investigated. Glutamate and aspartate concentrations in the cerebellar cortical tissues were markedly varied from case to case of MSA (OPCA) and CCA patients. However, glutamate concentration in the anterior vermis showed a positive correlation coefficient with the density of granule cells (r = 0.554, 0.05 less than P less than 0.10) and, those in the posterior vermis and in the cerebellar hemisphere were positively correlated with cells in the inferior olive (r = 0.707 and 0.607, P less than 0.05, respectively). Aspartate concentration in the anterior vermis also has a positive correlation coefficient (r = 0.571, 0.05 less than P less than 0.10) with the density of cells in the inferior olive. GABA concentrations in the dentate nucleus were decreased in all cases of MSA (OPCA) and CCA, and were positively correlated with the degree of loss of Purkinje cells (r = 0.765, P less than 0.01). ChAT activities were decreased in certain cases of MSA (OPCA), but conversely, increased in CCA patients. ChAT activity in the posterior vermis has a positive correlation coefficient (r = 0.613, 0.05 less than P0.10) with the cell density in the pontine nucleus. A possibility of a compensatory increase of ChAT activity in CCA patients was discussed.

Adult↗
PubMed1985

Processing of virus-specific glycoproteins of varicella zoster virus.

Monoclonal antibodies to varicella zoster virus (VZV) glycoproteins were used to study the processing of three glycoproteins with molecular weights of 83K-94K (gp 2), 64K (gp 3), and 55K (gp 5). Immunoprecipitation experiments performed with VZV-infected cells, pulse labeled with [3H]glucosamine in the presence of tunicamycin, suggest that O-linked oligosaccharide is present on the glycoprotein of gp 2. Use of the enzyme endo-beta-N-acetylglucosaminidase H revealed that the fully processed form of gp 3 had high-mannose type and that of gp 5 had only complex type of N-linked oligosaccharides. Experiments with monensin suggest that the precursor form (116K) of gp 3 is cleaved during the processing from Golgi apparatus to cell surface membrane. The extension of O-linked oligosaccharide chain and the complex type of N-linked oligosaccharide chains also occurs during this processing.

Antibodies, Monoclonal↗
PubMed1985

Mixed colloid cyst-xanthogranuloma of the third ventricle. A light and electron microscopic study.

A mixed colloid cyst-xanthogranuloma of the third ventricle is described. The xanthogranuloma associated with the cyst completely occupied the third ventricle. On light microscopy, a single epithelial layer with a basal lamina was seen lining the cyst wall. Electron microscopic study revealed three different kinds of cells in the epithelial layer: ciliated, nonciliated, and basal cells. Many lipid droplets were present in the superficial epithelial cells, macrophages, pericytes, and endothelia. The pathogeneses of the cyst and of the xanthogranuloma are discussed.

Brain Diseases↗
PubMed1985

Transient expression of glial fibrillary acidic protein in developing oligodendrocytes in vitro.

Expression of galactocerebroside (GC) and glial fibrillary acidic protein (GFAP) was studied in oligodendrocyte-enriched cultures of newborn mouse brains. In the cultures, GC was detectable as early as 1 day in vitro (1-DIV). Using double immunofluorescence labeling, some GC-positive cells were also stained homogeneously by the anti-GFAP serum. The intensity of GFAP staining increased until 9-DIV when the GC-positive cells revealed the typical morphology of oligodendrocytes, and the GFAP staining faded thereafter. The GFAP staining pattern of the GC-positive cells was not changed upon exposure to demecolcine, even though the GC-negative, GFAP-positive astrocytes showed perinuclear aggregation of GFAP. No intermediate filaments were observed in the oligodendrocytes by electron microscopy. The results suggest that the oligodendrocytes may have soluble GFAP in a certain period of early development.

Animals↗
PubMed1985

Cerebrovascular occlusive disease with and without the moyamoya vascular network in children.

Clinical features of cerebrovascular occlusive disease with the moyamoya network (group 1: twenty-nine children) and those without this network (group 2: nine children) are reported herein. Group 1 was characterized by female preponderance, recurrent and transient ischemic attacks, progression of mental deterioration, rebuild-up after hyperventilation on EEG and wide-spread lesions on CT scan. Group 2 had one or two attacks which led to a rather long-lasting hemiplegia but not to mental deterioration, rare rebuild-up findings on EEG and unilateral focal lesion on CT scan. Precipitating factors for ischemic attacks included deep breathing, changes in body temperature or sleep-waking transition were present in both groups. Etiology in some children was considered to be congenital.

Arterial Occlusive Diseases↗
PubMed1985

Comparative study on amino acid sequences of Kunitz-type soybean trypsin inhibitors, Tia, Tib, and Tic.

The amino acid sequences of three variants of the Kunitz-type trypsin inhibitors, Tia, Tib, and Tic, obtained from some cultivars of soybean were determined by conventional methods. All three inhibitors consisted of 181 amino acid residues. The differences in the amino acid sequences are as follows: Tia E12 G55 Y62 H71 S74 M114 L120 P137 L176; Tib S F N R V I T V; Tic E. The amino acid sequences of Pro(60)-Ser(61) and Asp(154)-Asp(155)-Gly(156)-His(157) of Tia reported previously (Koide & Ikenaka (1973) Eur. J. Biochem. 32, 417-431) were amended to Ser(60)-Pro(61) and His(154)-Asp-Asp-Gly(157), respectively.

Amino Acid Sequence↗
PubMed1985

Electrophysiological aspects of regulation of precapillary vessel tone in smooth muscles of vascular tissues.

The tone of precapillary vessels is regulated by free-Ca concentrations in the myoplasm. If the concentration of Ca decreases below 10(-7) M, the muscle relaxes. Maximal amplitudes of contraction are recorded when the concentration of Ca is higher than 5 X 10(-6) M. Certain aspects of Ca regulation require electrical activity of the cell membrane. To measure the electrical response under resting and active conditions, microelectrode, double-sucrose (current and voltage-clamp techniques), and single-current recording (patch-clamp) methods have been used. Measurements of membrane potential and conductance using the microelectrode method are essential to understand the property of the voltage-dependent Ca influx. It is also essential to make electrophysiological investigations for the analysis of the receptor-activated Ca influx. Excitatory junction potentials are one indicator of the activities of the pre- and postjunctional receptors as well as of the relative amount of transmitter released. Single currents have been recorded with the patch-clamp technique in isolated vascular smooth-muscle cells.

Action Potentials↗
PubMed1985

Moya moya disease: use of digital subtraction angiography in its diagnosis.

Fourteen patients suspected of having Moya Moya disease underwent intravenous digital subtraction angiography (DSA), and the findings from nine of these patients were reviewed and analyzed. Obstruction or stenosis of the supraclinoid portion of the internal carotid artery and the proximal portions of the anterior and middle cerebral arteries was observed in all cases. Arteriography, however, was better than intravenous DSA in demonstrating Moya Moya vessels, differentiating complete occlusion from severe stenosis, and demonstrating important transdural collaterals. The disadvantages of intravenous DSA included inferior spatial resolution, the need for large amounts of contrast media, and relatively high radiation doses. Since the summation of vessels cannot be avoided using DSA, arteriography is necessary for the precise evaluation of cerebral hemodynamics before bypass surgery. Intravenous DSA is a safe, reliable method for diagnosing Moya Moya disease and is suitable for the screening and follow-up examinations of patients with the disease.

Adolescent↗
PubMed1985

Cerebral-evoked responses elicited by direct stimulation of the lateral spinothalamic tract in the human.

The authors recorded cerebral-evoked responses elicited by direct stimulation of the human lateral spinothalamic tract (LST) during percutaneous cordotomy to investigate central conduction of noxious stimuli. These responses consisted of four negative potentials, peak latency being 3.8 (N1), 8.4 (N2), 12.2 (N3) and 21.9 (N4) ms respectively. N1 showed wide distribution over the scalp and was considered to be of subcortical origin. N2-N4 were distributed in both the temporal and central area. The different distribution pattern of N2-N4 from conventional somatosensory-evoked potential suggested a different projection of LST from the medial lemniscus system.

Adult↗
PubMed1985

Accessory nerve neurinoma mimicking a brain stem tumor on angiography: report of a case.

A case of accessory nerve neurinoma presenting with a so-called "intraaxial mass sign" on the angiograms is reported. The tumor originated from the intracranial portion of the accessory nerve and displaced the lateral medullary segment of the posterior inferior cerebellar artery posterolaterally. The displacement of the artery can be understood by the microanatomical relations.

Accessory Nerve↗
PubMed1985

Cardiac content and plasma concentration of atrial natriuretic polypeptide (ANP) in spontaneously hypertensive rats (SHR).

The cardiac content and plasma concentration of atrial natriuretic polypeptide (ANP) in hypertensive rats were measured by using radioimmunoassay for ANP. The animals used in this study were young (5-week-old) and adult (12- to 14-week-old) spontaneously hypertensive rats (SHR), stroke-prone SHR (SHR-SP) and normotensive control Wistar-Kyoto rats (WKY). Most immunoreactive ANP in the cardiac extract of the hypertensive rats (both SHR and SHR-SP) was found to be predominantly gamma-form as well as that of WKY. Cardiac ANP content in adult SHR and SHR-SP was significantly lower than in adult WKY (p less than 0.01), although there were no differences among three groups in young rats. Similar tendencies were also observed for plasma ANP concentration. The level of plasma in adult hypertensive rats was significantly lower or tended to be lower than in adult normotensive rats. Furthermore, a high negative correlation was present between blood pressure and cardiac ANP content (r = 0.748, p less than 0.01) and between blood pressure and plasma ANP concentration (r = 0.608, p less than 0.01) in all adult rats but there were no such relationships in young rats. The present study suggests that atrial natriuretic polypeptide may contribute to the pathogenesis or maintenance of high blood pressure in the genetic hypertensive rats.

Animals↗