PubMed Health⌕ Search

Biomedical subjects

K Kitamura

Publications and source records attributed to K Kitamura.

At least 1,279 records · Page 71Linked to original sources
PubMed1981

Rathke's cleft cyst.

Two cases of Rathke's cleft cyst which produced symptoms of compression of the optic chiasm are described. The first case has been followed for five years since the operation. No evidence of recurrence has been noticed. The prognosis after a partial removal of the cyst wall seems to be good with this lesion. In the second case, there was clinical and laboratory evidence of hypopituitarism and the CT scan revealed suggestive findings to differentiate the cyst from a pituitary adenoma.

Craniopharyngioma↗
PubMed1981

Cyst of the conus medullaris manifesting amyotrophic lateral sclerosis syndrome.

An intramedullary cyst of the conus medullaris was found in a 49-year-old man, who presented progressive amyotrophy in the lower extremities, without root pain or sensory impairment. The clinical manifestation resembled that of ALS, although there were some atypical features, such as urinary difficulty and atrophy in the lower limbs. Myelography demonstrated an intradural oval mass and a laminectomy revealed a cystic malformation of the conus medullaris. Drainage of the cyst resulted in a marked clinical improvement.

Amyotrophic Lateral Sclerosis↗
PubMed1981

Effects of vasodilator agents on smooth muscle cells of the coronary artery of the pig.

1 Effects of the vasodilator agents, papaverine, diltiazem, and sodium nitroprusside (SNP) on the electrical and mechanical activities of the smooth muscles of the coronary artery of the pig were compared.2 At a concentration of 10(-5) M, papaverine hyperpolarized and increased the ionic conductance of the membrane, SNP slightly hyperpolarized but diltiazem had no effect on the membrane potential and membrane ionic conductance.3 At a concentration of 10(-5) M, diltiazem abolished the spike evoked by outward current pulses in the presence of tetraethylammonium (TEA) 10 mM, while papaverine and SNP slightly reduced spike amplitude.4 The K-induced contraction produced by any given concentration of [K](o) over 20.2 mM was suppressed by diltiazem and SNP dose-dependently in concentrations greater than 10(-6) M; higher concentrations of papaverine were required to suppress contraction.5 The acetylcholine (ACh)-induced contraction was suppressed by diltiazem and SNP at concentrations greater than 10(-6) M and by papaverine in concentrations over 10(-5) M.6 In saponin-treated skinned muscles, papaverine, diltiazem and SNP had no effect on the pCa-tension relationship, i.e. these agents had no effect on the Ca receptor of contractile proteins. Furthermore, the caffeine-induced contraction in skinned muscles (after Ca loading) was not affected by these agents, i.e. the mechanism of Ca release by caffeine in skinned muscles was not affected.7 Chlorpromazine, an agent interacting with calmodulin, antagonized the contractile effect of calcium on skinned muscle fibres.8 The results obtained are discussed in relation to spike and contraction generating mechanisms, i.e. the effects of these agents on Ca influx and Ca release from stored sites. The results indicated that at equimolar concentrations diltiazem suppressed the mechanical response in the coronary artery of the pig more than SNP or papaverine.

Acetylcholine↗
PubMed1981

Neuromuscular transmission and smooth muscle membrane properties in the guinea-pig ear artery.

Effects of noradrenaline and alpha-adrenoceptor blocking agents on neuromuscular transmission of the guinea-pig ear artery were assessed using the micro-electrode method.1. The mean membrane potential, and length and time constants of the longitudinally oriented muscle cells were -64.5 +/- 5 mV (n = 150), 1.03 +/- 0.16 mm (n = 15) and 410 +/- 40 msec (n = 7) respectively. From the current-voltage relationship, weak outward current pulses produced an anomalous rectification of the membrane while stronger intensities produced a normal rectification of the membrane with a depolarization over 10-15 mV.2. Brief stimulation (0.1-0.5 msec) of the tissue produced an excitatory junction potential (e.j.p.). Facilitation produced by repetitive stimulation was evident only on very rare occasions. Higher stimulus intensities caused a stepwise increase of the amplitude of e.j.p.s.3. Spontaneously generated miniature excitatory junction potentials (m.e.j.p.s) were recorded from the muscle membrane. In many cells, the interval and amplitude histograms of m.e.j.p.s showed skew curves. On rare occasions, a bell-shaped amplitude distribution (quantal release of packeted noradrenaline (NA)) was observed.4. NA (> 3 x 10(-7)m) depolarized the membrane and increased the membrane resistance, as measured from the amplitude of the electrotonic potential. Phentolamine suppressed the NA-induced depolarization. However, high concentrations of phentolamine (> 10(-5)m) depolarized the membrane and increased the membrane resistance.5. NA (10(-8)m) caused no change in membrane potential though it suppressed the amplitude of an e.j.p. produced by a single stimulus, but did not suppress the amplitude of the subsequent e.j.p.s evoked by repetitive stimulation (0.2-2.0 Hz). A higher concentration of NA (3 x 10(-7)m) depolarized the membrane and markedly suppressed the amplitude of e.j.p.s. On the other hand, NA (10(-8) or 2 x 10(-8)m) generated burst discharges of m.e.j.p.s between silent periods or random generation.6. Phentolamine (10(-6)m) markedly enhanced the amplitude of e.j.p.s and caused a smooth facilitation in response to a train of stimuli with no effect on the membrane potential. A stepwise change in the amplitude of e.j.p.s was no longer observed at any given stimulus frequency and intensity.7. Phenoxybenzamine (10(-7)m) suppressed the amplitude of e.j.p.s with no change in the membrane potential.8. The results led to the conclusion that, at a concentration which has no effect on the post-junctional muscle membrane, NA and phentolamine seemed to be more effective on prejunctional adrenoceptors, while phenoxybenzamine seemed to have a greater effect on post-junctional adrenoceptors. NA depresses adrenergic transmission by negative feed-back, while the enhancing action of phentolamine can be explained partly by blocking of prejunctional adrenoceptors and, in addition, by an increase of NA release.

Animals↗
PubMed1981

Evidence that histamine and carbachol may open the same ion channels in longitudinal smooth muscle of guinea-pig ileum.

1. Membrane potential was recorded intracellularly by micro-electrode in separated longitudinal muscle of guinea-pig ileum. Electrotonic potentials were evoked in longitudinal strips by passing current between large external electrodes in the partition chamber.2. Histamine increased the frequency of action potential discharge at low concentrations and depolarized the membrane. At higher concentrations it caused substantial depolarization and action potential discharge was abolished. Carbachol had similar actions but the maximal depolarization by carbachol (using 10(-4)m) was some 4-5 mV greater than maximal depolarization by histamine (using 10(-4)m).3. The change in size of evoked electrotonic potentials was used to estimate the effects of carbachol and histamine on the conductance of the smooth muscle membrane. The equilibrium potentials for histamine and carbachol depolarizations were estimated from their relative effects on potential and conductance and were found to be not significantly different; measurements of the effects on conductance showed that 10(-4)m-histamine increased conductance about 8-fold whilst 10(-4)m-carbachol had a much greater effect on conductance. This difference could explain the differing maximal depolarizing effects of these agents if both were assumed to open channels having the same ionic selectivity (i.e. equilibrium potential).4. The efflux of (42)K was studied in separated strips of longitudinal ileal muscle from guinea-pig. In the presence of a concentration of carbachol (2 x 10(-5)m or 10(-4)m) having a maximal effect on (42)K efflux rate, histamine (10(-4)m) did not increase efflux further although 120 mm-potassium did so. Experiments with the irreversible muscarinic receptor blocker, propylbenzilylcholine mustard, indicated that the number of muscarinic receptors did not limit the (42)K efflux response to carbachol and it was suggested that the response was limited by the availability of ion channels which could be opened by activated muscarinic receptors.5. Contractions to histamine and carbachol in 120 mm-potassium depolarizing solution were followed upon washing by a relaxation below basal tension. Carbachol, but not histamine, showed a pronounced and long lasting secondary contraction following this relaxation.6. These results are consistent with the idea that activated histamine and activated muscarinic receptors open the same ion channels in the smooth muscle membrane to produce depolarization, increased action potential discharge and contraction, although muscarinic receptors can open more of these. However, there was evidence that the opening of these channels is not the only pathway between receptor activation and contraction.

Animals↗
PubMed1981

Establishment and maintenance of a human glioma transplanted serially to hereditary asplenic-athymic (lasat) mice.

A tumor line in asplenic-athymic (lasat) mice designated KNS-GL-2 was established from a recurrent anaplastic astrocytoma of the cerebrum in a 15-year-old boy (NS761072). The tumor line increased in terms of the rate of tumor take and growth with serial passage, forming a nodular appearance and massive intratumoral hemorrhage at the third generation. Microscopically, tumors developed in lasat mice wee similar to the original tumor and consisted of cells with round and oval nuclei and a clear cytoplasm, which was positive for S-100 and GFA proteins by the immunoperoxidase method. Large clusters of tumor cells with dark scanty cytoplasm seen at the third generation lost their astrocytic appearance and were negative for both S-100 and GFA proteins. This was considered to be evidence for dedifferentiation or malignant transformation. There was a scattering of tumor cells with clear cytoplasm in these clusters, with a positive reaction to S-100 protein. It was possible that tumor cells dedifferentiated during serial passage but still retained the potential to differentiate into astrocytes.

Animals↗
PubMed1981

Therapeutic effect of pyritinol on sequelae of head injuries.

Two hundred and seventy patients suffering from the sequelae of different forms of brain injury have been treated orally with pyritinol 200 mg three times a day for a period of 6 weeks. It has been shown that, compared with placebo therapy, pyritinol produces statistically significant improvement in the clinical and psychoneurological manifestations. It is concluded that pyritinol is a drug of therapeutic benefit in the treatment of the sequelae of cerebral trauma.

Adolescent↗
PubMed1981

Effects of 2-nicotinamidoethyl nitrate on smooth muscle cells and on adrenergic transmission in the guinea-pig and porcine mesenteric arteries.

Muscle membranes of the porcine but not guinea-pig mesenteric artery wee hyperpolarized by applications of over 10(-6) M 2-nicotinamidoethyl nitrate (SG 75; 2-NN) dose-dependently from -53 to -72 mV, due to an increase in the ionic conductance of the membrane. In the porcine mesenteric artery but not guinea-pig, 2-NN suppressed the K-induced contraction in concentrations below 20 mM [K]0. The suppression of the K-induced contraction depended on the degree of hyperpolarization and the level of the resting membrane potential. The norepinephrine-induced contraction was suppressed by 2-NN with hyperpolarization of the membrane in the porcine mesenteric artery, but with no change in the membrane potential in the guinea-pig mesenteric artery, presumably due to suppression of the Ca-mobilization in the cell. The excitatory junction potential (ejp) could be recorded by perivascular nerve stimulation in both mesenteric arteries. Whether or not the membrane was hyperpolarized, 2-NN increased the amplitude of ejp in both tissues and increased the appearances of miniature ejp in the guinea-pig mesenteric artery. Nitroglycerin did not modify the membrane potential, the amplitude of ejp, electrical threshold and spike superimposed on the ejp, while sodium nitroprusside suppressed the amplitude of ejp, the facilitation process produced by repetitive stimulation and the spike superimposed on the ejp. Specific features of 2-NN actions on the muscle cell and adrenergic transmission of the mesenteric arteries in both species were discussed in relation to vasodilating actions, species differences and also in relation to other nitrite compounds.

Action Potentials↗
PubMed1981

Vasodilating actions of 2-nicotinamidoethyl nitrate on porcine and guinea-pig coronary arteries.

Effects of 2-nicotinamidoethyl nitrate (2-NN) on smooth muscle cells of porcine and guinea-pig coronary arteries were investigated by the microelectrode and double sucrose-gap methods and from isometric contractions. In the dose over 2 X 10(-6) M in the guinea-pig coronary artery and over 5 X 10(-6) M in the large and small porcine coronary arteries, the membrane was hyperpolarized and the ionic conductance of the membrane was increased. This hyperpolarization appeared more dominantly in low [K]0. The action was estimated to be due to increase in the K-conductance of the membrane in both species. The spike with an overshoot evoked by electrical stimulation in the presence of tetraethylammonium chloride (TEA) was suppressed by 2-NN, mainly due to hyperpolarization of the membrane and not to suppression of Ca-carriers at the membrane. The contraction evoked by electrical depolarization, acetylcholine (ACh), excess [K]0 or repetitive short pulse stimulation was suppressed in the presence of 2-NN with a concentration similar to that which hyperpolarized the membrane. The suppression of the mechanical response is postulated to be mainly due to hyperpolarization of the membrane and in part to suppression of the Ca-mobilization from the storage sites in the cell. The former seems to be the main action of 2-NN on the coronary arteries in both species. Definite differences on 2-NN actions between the large and small porcine coronary arteries were not observed, but the contraction evoked in the large coronary artery was suppressed slightly more by 2-NN. Vasodilation which occurs with application of 2-NN is discussed in relation to that induced by nitroprusside or nitroglycerin.

Animals↗
PubMed1981

Distribution of endogenous beta-galactoside-specific lectin, fibronectin and type I and III collagens during dermal condensation in chick embryos.

The distribution of endogenous beta-galactoside-specific lectin, fibronectin, type I and III collagens was studied by the indirect immunofluorescence method during the formation of dermal condensation in the feathered region (dorsal skin) of a chick embryo. Endogenous beta-galactoside specific lectin was concentrated in the condensed dermal region, coinciding with the formation of condensation of dermal cells. It was also detected in epidermal placodes. Fibronectin was weakly stained in dermis prior to the formation of dermal condensation but not in epidermis. Condensation of dermal cells resulted in the formation of thicker fibrils of fibronectin in the condensed region. Distribution of type I collagen was found to be very different from that of endogenous beta-galactoside-specific lectin and fibronectin. Type I collagen in dermis decreased along with the formation of dermal condensation. Epidermis had no type I collagen. Type III collagen was not found in dorsal skin. Relationship found between these distribution patterns and dermal condensation in the embryonic chick skin is discussed.

Animals↗