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Biomedical subjects

K Kitamura

Publications and source records attributed to K Kitamura.

At least 1,315 records · Page 73Linked to original sources
PubMed1980

Angiographic diagnosis of acoustic neurinomas and meningiomas in the cerebellopontine angle--a reappraisal.

Forty-two acoustic neurinomas and seven meningiomas in the cerebellopontine angle were reviewed, and the radiological differential diagnosis of these tumors is discussed. Though enlarged internal auditory meati and characteristic CT findings were reasonably reliable indicators for the diagnosis of acoustic neurinomas, it was angiography which substantiated their correct diagnosis. An arcuate vein was frequently demonstrated with acoustic neurinomas, but never with meningiomas. Visualization of tangled veins seems to favor a diagnosis of acoustic neurinomas. Contrary to earlier reports, tumor stains were most frequently visualized using selective external carotid arteriography. The degree of tumor stains did not aid in differentiating acoustic neurinomas from meningiomas. The importance of using angiotomography, especially in the anteroposterior projection, and external carotid angiography during prolonged injections of large amounts of contrast media, is emphasized.

Basilar Artery↗
PubMed1980

Irradiated meningiomas: a clinical evaluation.

Eighteen cases of intracranial meningioma that received preoperative or postoperative irradiation with 60Cobalt or Linac have been reviewed. Eight patients received preoperative irradiation because their tumours were very large, hypervascular, and surgically not readily accessible. Two angioblastic meningiomas of the haemangiopericytoma type responded well to irradiation and were easily extirpated. One of these developed a local recurrence and metastases to the lungs and liver nine years after surgery. The recurrent intracranial tumour and nodules in the lungs responded well to irradiation. The other six cases of meningiomas of meningothelial, transitional, or haemangioblastoma types, did not improve clinically or radiologically after irradiation. Ten cases received postoperative irradiation because their tumours were only partially removed or were histologically malignant. In all cases irradiation was most effective for recurrent tumours of the haemangiopericytoma type. This study indicates that irradiation is useful in tumours of the haemangiopericytoma type as an adjunct to surgery or for palliation in advanced stages. Irradiation may been effective in supressing recurrences in two cases of other types of meningioma, although the number of cases is too small to allow any definite conclusion.

Adult↗
PubMed1980

A footpad weight assay method to evaluate delayed-type hypersensitivity in the mouse.

Delayed-type hypersensitivity lesions have been difficult to evaluate objectively in the mouse. They are usually evaluated by measurement of footpad swelling or increased ear thickness after challenge with antigen. I have developed a footpad weight assay method which reduces the observer's error and the instrumental error. This method is reliable for the assessment of delayed-type hypersensitivity reactions when results are expressed as weight increase or weight ratio calculated on challenged and unchallenged footpad.

Animals↗
PubMed1980

The existing forms of collagenase in the human uterine cervix.

The existing forms of collagenase [EC 3.4.24.7] in the human uterine cervix were examined. The latent collagenase extracted by homogenization in 0.25% Triton X-100 containing 0.01 M CaCl2 was indicated to be a complex of collagenase with alpha 2-macroglobulin by the behavior of the fraction of this enzyme before and after treatment with NaSCN on Sephadex G-150 column chromatography and an immunodiffusion method. The active collagenase was extracted by rehomogenization in 50 mM Tris-HCl buffer, pH 7.4, containing 0.1 M M CaCl2 from the insoluble residue at 0 degrees C. Another latent collagenase was extracted from the insoluble fraction in the same buffer by heating at 60 degrees C for 4 min and this enzyme was activated by 4-aminophenylmercuric acetate or trypsin. The molecular weights of the active and the latent forms were approximately 7.3 x 10(4) and 9.4 x 10(4), respectively. This indicates that the latency is due to the formation of a low molecular weight inhibitor enzyme complex. These results clarified that the human uterine cervix contains three existing forms (alpha 2-macroglobulin complex, active form and low molecular weight inhibitor complex) of collagenase under these experimental conditions.

Amino Acids↗
PubMed1980

Actions of nitroglycerine on the membrane and mechanical properties of smooth muscles of the coronary artery of the pig.

1 Effects of nitroglycerine (NG) on the membrane and contractile properties of the smooth muscle cell of the isolated coronary artery of the pig were observed.2 NG, up to a concentration of 10(-5) M, modified neither the membrane potential nor the membrane resistance. Increased concentrations of NG (> 2.8 x 10(-5) M) hyperpolarized the membrane, reduced the membrane resistance and enhanced the rectifying property of the membrane measured by depolarization pulses. These phenomena observed with a high concentration of NG are the result of an increase in the K-conductance of the membrane.3 NG (2.8 x 10(-5) M) did not modify the membrane potential displaced by various concentrations of excess [K](o). In low [K](o), NG (2.8 x 10(-5) M) hyperpolarized the membrane to a greater extent than that observed in Krebs solution. The effects of NG (10(-6) to 2.8 x 10(-5) M) on the membrane potential were not modified by simultaneous application of 2 x 10(-6) M acetylcholine (ACh).4 NG (2.8 x 10(-6) M) consistently raised the mechanical threshold required for tension development and suppressed the amplitude of the contraction evoked by excess [K](o), ACh or electrical depolarization of the membrane. The dose-response curve shifted to the right in the presence of NG noncompetitively in all the conditions employed to develop the tension.5 When the tissue was immersed in Ca-free (EGTA) solution, ACh (5 x 10(-6) M) evoked a contraction even after the tissue had lost the ability to contract to repetitive applications of 118 mM [K](o) in Ca-free (EGTA) solution. However, the tissue finally failed to contract to repetitively applied ACh. At this stage, 2.5 mM [Ca](o) evoked a small contraction, after which the response was briefly restored to 5 x 10(-6) M ACh. This transient response to ACh was reduced by NG (5.6 x 10(-6) M) when NG was added either simultaneously with ACh or with the previous Ca application. However, the inhibition was greater in the former than the latter case.6 Cysteine (1 to 2 mM), without modifying the membrane potential or membrane resistance, partly restored the contraction evoked by excess [K](o) or ACh which had been reduced by NG.7 The mechanism of action of NG on the smooth muscle cell of the coronary artery of the pig is postulated to be due to a nonselective suppression of the Ca-mobilization from the store site with no noticeable change in the membrane properties.

Acetylcholine↗
PubMed1980

Actions of 4-aminopyridine on vascular smooth muscle tissues of the guinea-pig.

1 Effects of 4-aminopyridine (4-AP) and procaine on the membrane and contractile properties of smooth muscle cells of the guinea-pig pulmonary artery and portal vein were observed.2 The membrane potential and length constant of smooth muscle cells of the guinea-pig pulmonary artery were -53.2 mV and 1.2 mm, respectively, and those of the portal vein were -52.6 mV and 0.71 mm, respectively. The membrane was electrically quiescent in the pulmonary artery and it was electrically active in the portal vein.3 Both 4-AP and procaine depolarized the membrane, increased the membrane resistance and suppressed the rectifying properties in both tissues. Both agents evoked a graded response from the muscle membranes of the pulmonary artery by outward current pulse. Procaine had a greater effect than 4-AP on the above membrane properties.4 4-AP (10(-5) M) produced contraction without depolarization of the membrane. The contraction evoked by 10(-5) M 4-AP was completely suppressed but that evoked by 5 x 10(-4) M 4-AP was only partly suppressed by phentolamine (10(-7) M). However, the contraction evoked by procaine was not suppressed by phentolamine.5 4-AP enhanced but procaine suppressed the amplitude of 118 mM [K](0)-induced contraction.6 The results suggest that 4-AP and procaine suppress K-conductance of the muscle membrane, and 4-AP but not procaine increases noradrenaline release from the nerve terminal. Presumably intracellular free Ca concentrations are also modified by these agents. The effects of 4-AP and procaine on the vascular muscle were compared with those on other excitable tissues.

4-Aminopyridine↗
PubMed1980

Nitroglycerine and catecholamine actions on smooth muscle cells of the canine coronary artery.

1. The membrane potential of smooth muscle cells of the canine coronary artery was - 52 mV, and cells were electrically quiescent. The length and time constant of the membrane were 0.83 mm and 410 msec, respectively. 2. TEA (> 10(-3) M) depolarized the membrane, increased the membrane resistance and suppressed the rectifying property of the membrane. In 10(-2) M-TEA, an outward current pulse evoked a small active response in the canine coronary artery and a large response in the porcine coronary artery. 3. In the canine coronary artery, the minimum [K]o required for contraction was 11.8 mM (-48 mV), and the maximum amplitude of the contraction was evoked in 89 mM-[K]o (-13 mV). The maximum depolarization produced by a tenfold increase in [K]o was 49 mV. 4. In the canine coronary artery, isoprenaline and a low concentration of phenylephrine reduced the resting tension, and a high concentration of phenylephrine (> 5 x 10(-5) M) produced a contraction without affecting the membrane properties. 5. Nitroglycerine reduced resting tension, suppressed the amplitude and raised the threshold of contraction evoked by excess [K]o, electrical depolarization or phenylephrine. In the canine coronary artery, the minimum concentration of nitroglycerine required to suppress K-induced contraction (17.7 mM) was 2.8 x 10(-12) M nitroglycerine. However, resting membrane properties were not affected by 2.8 x 10(-5) M nitroglycerine. TEA induced electrical response was only a little depressed by 2.8 x 10(-5) M nitroglycerine in the porcine coronary artery, while the mechanical response was markedly suppressed. 6. In the canine coronary artery, adenosine (> 10(-5) M) relaxed the tissue in the presence of 17.7 M-[K]o without affecting the membrane property. ACh (> 5 x 10(-5) M) had much the same effects as those observed by treatment with adenosine.

Acetylcholine↗
PubMed1980

Prolonged injection angiography for diagnosing intracranial neoplasms.

Prolonged injection angiography (PIA), in which large amounts of contrast material are administered for three or four seconds, was used to visualize the vasculature of 70 intracranial neoplasms. Tumor stains were demonstrated better with or solely by PIA in all pituitary adenomas with suprasellar extension and in most meningiomas. PIA was less effective in tumors with marked arteriovenous shunts or in low-grade gliomas. PIA is especially indicated when avascular or hypovascular masses are encountered on conventional angiography or when contrast enhancement is encountered on computed tomography (CT). PIA is also indicated to demonstrate neoplasms which are not enhanced with contrast media on CT since PIA demonstrates the venous anatomy surrounding the tumors especially well.

Adenoma↗
PubMed1980

Alterations of immunoreactive beta-endorphin in the third ventricular fluid in response to electrical stimulation of the human periaqueductal gray matter.

Immunoreactive beta-endorphin in the third ventricular fluid was measured in response to electrical stimulation of the periaqueductal gray matter in 8 patients with intractable pain during rostral mesencephalic reticulotomy for pain relief. In all patients, marked increase of immunoreactive beta-endorphin was observed. On the other hand, in cases of electrical stimulation of the zona incerta performed during stereoencephalotomy, in 5 patients with involuntary movement, immunoreactive beta-endorphin in the third ventricular fluid did not show any significant change. The authors conclude that the increase of immunoreactive beta-endorphin on electrical stimulation of the periaqueductal gray matter is not a nonspecific response to brain stimulation but a specific response in regard to cerebral localization of endorphins. Direct correlation between pain relief and periaqueductal gray stimulation is also questioned.

Adult↗
PubMed1980

Blood flow of the ipsilateral and contralateral lower limbs after isometric contraction.

Calf and thigh blood flows in both of right and left legs were measured simultaneously after isometric contraction of the right thigh muscle. Isometric contraction was performed at a force of about 50% of maximal voluntary contraction for 15 sec. The thigh blood flow of the right leg increased immediately after voluntary contraction in all subjects, while the calf blood flow of right leg decreased conversely in spite of exercised ipsilateral leg.

Adult↗