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Biomedical subjects

T Koizumi

Publications and source records attributed to T Koizumi.

At least 163 records · Page 9Linked to original sources
PubMed1997

[Transarterial embolization of a vein of Galen aneurysm: a case report].

This report describes a case of a vein of Galen aneurysm. A 6-month-old baby with a slight head injury was referred to our hospital. CT scans and MR images demonstrated a vein of Galen aneurysm. Left carotid angiogram showed a vein of Galen aneurysm with a large feeding artery from the posterior cerebral artery. Transarterial embolization was performed using Galen coils and Interlocking Detachable Coils. Angiograms after the second embolization revealed complete occlusion of the aneurysm and postoperative course was uneventful.

Cerebral Angiography↗
PubMed1997

[Two patients with summer-type hypersensitivity pneumonitis in Nagano Prefecture].

We encountered two patients with summer-type hypersensitivity pneumonitis that developed in Nagano Prefecture. Patient 1 was a 61-year-old man who had worked in warm and humid environments as painter. He was referred to our hospital because of fever, coughing and exertional dyspnea. Respiratory symptoms developed during work but were gone within in few weeks. Patient 2 was a 50-year-old housewife who was admitted to our hospital because of persistent coughing and a low-grade fever. In both patients, chest roentgenograms and computed tomograms showed bilateral, small, nodular and reticular shadows. Examination of a specimen obtained from patient 2 by transbronchial lung biopsy revealed alveolitis. In both patients, bronchoalveolar lavage fluid had low CD4/8 ratios, but in patient 1 the lymphocyte fraction was high and in patient 2 the neutrophil fraction was high. A steroid drug was given to patient 1 because of the patients symptoms and prolonged abnormal roentgenographic findings. Patient 2 reacted positively on a provocation test when returned to her house. Serum from both patients contained antibodies to Trichosporon mucoides and T. asahii. We know of no previous reports of summer-type hypersensitivity pneumonitis that developed in Nagano prefecture.

Alveolitis, Extrinsic Allergic↗
PubMed1997

[Histological findings in aneurysm treated with IDC: scanning electron microscopical study].

We reported the scanning electron microscopic findings of an aneurysm embolized with interlocking detachable coils (IDC). A 78-year-old man was referred to our hospital because of left hemiparesis and dysphagia. CT scan showed multiple lacunar infarction in the bilateral corona radiata. Angiography demonstrated a small incidental aneurysm of the right internal carotid artery (IC-PC junction). The left hemiparesis gradually improved and 2 weeks after admission the aneurysm was treated with IDC. Three coils were placed in the aneurysm and post-operative angiography demonstrated complete embolization. Dysphagia caused by the pseudobulbar pulse did not improve and, 4 weeks after endovascular surgery, the patient died of aspiration pneumonia. An autopsy was performed and the scanning electron microscopical findings of the aneurysm showed development of endothelial cells on the coil surface. Many clinical reports supported the usefulness of Guglielmi detachable coils (GDC) and several experimental reports demonstrated the intimal proliferation in aneurysms embolized with coils. However, pathological changes of the aneurysms treated with coils have been reported in only four clinical cases. There was no evidence of endothelialization in any of these cases. To our knowledge, our case is the first report describing the endothelial proliferation over the coils. It is necessary to accumulate histopathological data and long-term follow-up in humans treated with coils.

Aged↗
PubMed1997

[Dissecting aneurysm of the middle cerebral artery with subarachnoid hemorrhage and brain infarction: a case report].

This report describes a surgical case of a dissecting aneurysm of the left middle cerebral artery with subarachnoid hemorrhage and ischemic insult. A 48-year-old man with pure motor aphasia was referred to our hospital. CT scans demonstrated subarachnoid hemorrhage in the left frontal region. CT scans on the next day showed a small brain infarction in the left precentral artery and central artery territories. The first left carotid angiograms showed stenosis at the M2 portion of the middle cerebral artery. On the 16th day, the second left carotid angiograms revealed a pearl and string sign. We diagnosed a dissecting aneurysm of the middle cerebral artery. The dissecting aneurysm was wrapped using the pterional approach and STA-MCA anastomosis was also performed. The postoperative course was uneventful and the motor aphasia improved.

Aortic Dissection↗
PubMed1997

[Estimation of 123I-metaiodobenzylguanidine lung uptake in heart and lung diseases--with reference to lung uptake ratio and decrease of lung uptake].

123I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy was performed in 64 patients with heart and lung diseases. Distribution of MIBG in the chest was evaluated by planar images, using counts ratios of the heart to the mediastinum (H/M) and the unilateral lung to the mediastinum (Lu/M). Most of patients with heart diseases showed obvious lung uptake of MIBG. The ratios of H/M were 1.75 +/- 0.20 in the group without heart failure and 1.55 +/- 0.19 in the group with heart failure. The ratios of Lu/M in the right and left lung were 1.56 +/- 0.16 and 1.28 +/- 0.16 in the group without heart failure. And those were 1.45 +/- 0.16 and 1.19 +/- 0.15 in the group with heart failure. But 3 patients complicated with chronic pulmonary emphysema and one patient with interstitial pneumonia due to dermatomyositis showed markedly decreased lung uptake. The ratios of Lu/M in the right and left lung of these patients were 1.20, 1.17; 1.17, 1.13; 1.01, 0.97 and 1.27, 0.94, respectively. These results suggest that the lung uptake of MIBG may reflect the state of pulmonary endothelial cell function in clinical situations, considering that it has been demonstrated that MIBG may be useful as a marker of pulmonary endothelial cell function in the isolated rat lung.

3-Iodobenzylguanidine↗
PubMed1997

[Myocardial scintigraphic studies with 123I-MIBG, 201Tl and 99mTc-PYP in patients with cardiac amyloidosis].

Myocardial scintigraphic studies, using 123I-metaiodobenzylguanidine (MIBG), 99mTc-pyrophosphate (PYP) and 201Tl were performed in 4 patients with cardiac amyloidosis. In MIBG myocardial images, 2 patients with familial amyloid polyneuropathy (FAP) showed complete or partial defect and the other 2 with primary amyloidosis had normal myocardial uptake of MIBG. In PYP myocardial images, diffuse myocardial uptake of PYP was mild in 2 patients with FAP and moderate in the other 2. 201Tl myocardial images revealed normal myocardial uptake of 201Tl in 2 patients with FAP and 1 with primary amyloidosis, and intense myocardial uptake in the other one with primary amyloidosis. These results suggest that myocardial scintigraphies with PYP and 201Tl may be useful for the detection of cardiac amyloidosis and estimation of its pathophysiology. And MIBG myocardial scintigraphy may provide useful information about sympathetic nerve abnormalities which vary with type of the fibril protein, clinical syndromes and disease process of cardiac amyloidosis.

3-Iodobenzylguanidine↗
PubMed1996

Mechanism of cadmium-induced cytotoxicity in rat hepatocytes: cadmium-induced active oxygen-related permeability changes of the plasma membrane.

The present study was performed to further elucidate the mechanism of cadmium (Cd)-induced cytotoxicity in rat hepatocytes focusing on the effects of Cd-induced acidification on cellular production of H2O2 and the integrity of the plasma membrane. Exposure of cells of Cd levels < 50 microM stimulated cellular production of H2O2 in a dose-dependent manner. In cells exposed to 50 microM Cd, generation of the toxic oxygen increased from 5 min after exposure, and reached a plateau at 15 min. The acidic medium at pH 6.5, a value which is corresponding to the cellular pH at maximal acidification induced by Cd, also enhanced production of the active oxygen at almost the same level as 25 microM Cd. These treatments affected permeability barrier of plasma membranes as assessed by nuclear staining with propidium iodide (PI, MW 668) and release of intracellular lactic dehydrogenase (LDH) into surrounding medium. Cd at 50 microM caused nuclear staining by the fluorescent probe, beginning from 15 min at exposure, reaching a peak at 60 min. LDH leakage likewise started from 60 min of Cd exposure onward. The acidic partially prevented by L-ascorbic acid pretreatment. H2O2-induced nuclear staining increased with the increasing pH values from 6.7 to 7.1 Cd at 50 microM lowered the cellular pH within 5 min, but the decreased cellular pH returned to a value near physiological levels 25 min later. Pretreatment with Amiloride, an inhibitor of the Na+/H+ exchange, partially blocked this pH recovery after acidification. The results indicate that Cd caused H2O2 accumulation and H+, Cd and H2O2-related permeability changes of the plasma membrane. This may link to subsequent extensive membrane damage occurring at near physiological cellular pH.

Amiloride↗
PubMed1996

Altered antigen receptor signaling and impaired Fas-mediated apoptosis of B cells in Lyn-deficient mice.

Mice deficient in the src related protein tyrosine kinase, Lyn, exhibit splenomegaly and accumulate lymphoblast-like and plasma cells in spleen as they age, resulting in elevated levels of serum IgM (10-20-fold of control) and glomerulonephritis due to the presence of immune complexes containing auto-reactive antibodies. It remains unclear, however, how antibody-producing cells are accumulated in the lymphoid tissues of Lyn-/- mice. To elucidate the role of Lyn in B cell function, we have studied the proliferative responses to various stimuli and Fas-mediated apoptosis in B cells from young Lyn-/- mice which do not yet show apparent abnormality such as splenomegaly. Compared with control B cells, Lyn-/- B cells were hyper responsive to anti-IgM-induced proliferation and defective in Fc gamma RIIB-mediated suppression of B cell antigen receptor (BCR) signaling, indicating that Lyn is involved in the negative regulation of BCR signaling. In addition, the BCR-mediated signal in Lyn-/- B cells, unlike that in control B cells, failed to act in synergy with either CD40- or IL-4 receptor-triggered signal in inducing a strong proliferative response, suggesting that the BCR signaling pathway in Lyn-/- B cells is altered from that in control B cells. Furthermore, Lyn-/- B cells were found to be impaired in the induction of Fas expression after CD40 ligation and exhibited a reduced susceptibility to Fas-mediated apoptosis. Moreover, BCR cross-linking in Lyn-/- B cells suppressed Fas expression induced by costimulation with CD40 ligand and IL-4. Collectively, these results suggest that the accumulation of lymphoblast-like and plasma cells in Lyn-/- mice may be caused in part, by the accelerated activation of B cells in the absence of Lyn, as well as the impaired Fas-mediated apoptosis after the activation.

Animals↗
PubMed1996

Regulation of bcl-xL expression and Fas susceptibility in mouse B cells by CD40 ligation, surface IgM crosslinking and IL-4.

CD40 is one of the key molecules involved in the survival, growth and differentiation of B lymphocytes. In contrast, Fas (Apo-1, CD95) mediates apoptosis of a variety of cell types, including lymphocytes. Recent studies have found that Fas expression on mouse B cells could be strongly induced by CD40 ligation, a helper T cell-derived signal. Here, evidence is provided that CD40 ligation induced two distinct signals: one leading to the upregulation of Fas and the other leading to the enhanced Fas susceptibility. B lymphoma cell lines, CH31 and WEHI279, expressed Fas on cell surfaces, but were resistant to anti-Fas antibody (Ab) induced apoptosis. Treatment with CD40 ligand (CD40L), however, greatly enhanced Fas susceptibility of these cells. Similarly, normal splenic B cells became highly susceptible to Fas-mediated apoptosis following prolonged signaling through CD40. While CD40 ligation enhanced Fas-mediated apoptosis, stimulation with anti-IgM and IL-4 partially protected CD40L-activated B cells from Fas-mediated apoptosis. It was found that bcl-xL gene expression in normal splenic B cells was induced drastically by treatment with anti-IgM and IL-4, but not CD40L. By contrast, the expression of bcl-2 or bax was not significantly affected by these treatments. Moreover, in three of the four B lymphoma cell lines tested, Fas susceptibility correlated with the status of bcl-xL expression. The data suggest that an increase in bcl-xL expression may protect B cells from Fas-mediated apoptosis.

Animals↗
PubMed1996

Kinetics of swelling of compressed cellulose matrices: a mathematical model.

PURPOSE: A model for swelling time course of compressed cellulose matrix is presented. METHODS: The model incorporates the two most important features: water penetration by diffusion and volume change due to swelling. Approximations of the model for small t values and for large t values are also derived, which are utilized in a handy routine for estimation of swelling parameters. RESULTS: The observed time courses of thickness change with compressed matrices of methyl cellulose and hydroxypropyl cellulose agree well with the calculated values of the proposed model. CONCLUSIONS: The proposed model is compatible with the observed swelling kinetics.

Cellulose↗
PubMed1996

Systemic air embolism in an extremely low birthweight infant treated with high-frequency oscillatory ventilation.

An extremely low birthweight infant in whom systemic air embolism occurred during high-frequency oscillatory ventilation is reported. He was delivered at 25 weeks and 6 days gestation weighing 600 g. He was diagnosed as having respiratory distress syndrome and had intermittent mandatory ventilation. At 2 days of age, there was pulmonary hemorrhage and high-frequency oscillatory ventilation was 22 cmH2O. At 9 days of age, X-ray film revealed air in the intracardiac cavity and major systemic vessels. Systemic air embolism can occur in an extremely low birthweight infant having high-frequency oscillatory ventilation with a mean airway pressure of 22 cmH2O or higher.

Embolism, Air↗
PubMed1996

Influence of pH on skin permeation of amino acids.

Skin permeation of amino acids through excised rat skin was measured at various pH values. The permeabilities varied with the donor pH and amino acid, indicating that each ionic species of amino acid may have a different permeability. The permeability coefficient of each ion was estimated from the permeability-pH profiles using the dissociation constants. The estimated values for mono-cation and uncharged zwitterion were not dependent on the lipophilicity but on the size of the amino acid, suggesting a porous mechanism of transport. The permeability coefficient was highest for di-cation, followed by mono-cation, positively charged, uncharged and negatively charged zwitterions. The electrical potential difference across the skin was too small to affect the permeation of ions. The permselective property of skin thus seems to be determined by the difference of diffusivity in aqueous pores of skin due to the hydration of ions and other factors.

Amino Acids↗
PubMed1996

Cytokines in bronchoalveolar lavage fluid in patients with high altitude pulmonary oedema at moderate altitude in Japan.

BACKGROUND: The precise mechanism of high altitude pulmonary oedema (HAPE) remains unclear. The purpose of this study was to evaluate the role of cytokines and P-selectin in the development of HAPE which occurred at moderate altitude in Japan. METHODS: The following cellular and biochemical markers and chemotactic cytokines were measured in the bronchoalveolar (BAL) fluid from four patients with HAPE at 2857-3180 m in the Japanese Alps: total proteins, albumin, lactate dehydrogenase (LDH), and interleukin (IL)-1 alpha, IL-1 beta, IL-1 receptor antagonist (ra), IL-6, IL-8, IL-10, tumour necrosis factor (TNF)-alpha, and the soluble form of P-selectin. RESULTS: At admission there were significant increases in the levels of total cells, especially macrophages and neutrophils, total protein, albumin and LDH when compared with 13 healthy individuals. Furthermore, the levels of IL-1 beta, IL-6, IL-8, and TNF-alpha were also considerably increased but returned quickly to the normal ranges or were not detected after recovery. The levels of IL-1 alpha, IL-10, and P-selectin did not change. CONCLUSIONS: These results suggest that an inflammatory process almost identical with acute respiratory distress syndrome (ARDS) may occur in HAPE, but that these changes are transient and are not associated with any increase in P-selectin levels in the BAL fluid.

Adult↗
PubMed1996

Nitric oxide and nitroglycerin reversal of pulmonary vasoconstriction induced by alpha-activation during exercise.

We have previously shown in sheep that pulmonary vascular resistance decreases rapidly after the onset of constant exercise, followed by a slower and smaller second vasodilation. The second phase is partly regulated by alpha- and beta-adrenoceptor activation. We examined the effect of inhaled nitric oxide (NO; 40 ppm) and intravenous nitroglycerin on beta-adrenergic blockade-induced pulmonary vasoconstriction during exercise. In paired studies, we exercised eight sheep at a constant rate of 4 miles per hour for 4 min on a treadmill and measured the hemodynamic response during beta-blockade (propranolol, 1 mg i.v.) with and without 40 ppm inhaled NO or continuous infusion of nitroglycerin (3.2-4.0 micrograms.kg-1.min-1). beta-Blockade resulted in a higher pulmonary vascular resistance during steady-state exercise (40-240 s) than in the unblocked state; reduction in pulmonary vascular resistance during the second phase of exercise was smaller with beta-blockade (13-16%) than with control exercise (26-30%). Inhaled NO and nitroglycerin reversed the beta-blockade-related pulmonary vasoconstriction to the levels of control exercise. Inhaled NO and intravenous nitroglycerin also reversed the pulmonary vasoconstriction produced by intravenous phenylephrine at rest. We conclude that exogenous NO, delivered by gas inhalation or via nitroso compounds, opposes and fully reverses alpha-receptor-activated pulmonary vasoconstriction during exercise in sheep.

Administration, Inhalation↗
PubMed1996

Endothelin-1 and interleukin-8 in high altitude pulmonary oedema.

We present a case of high altitude pulmonary oedema (HAPE) with pulmonary hypertension and polymorphonuclear leucocyte (PMN) accumulation in bronchoalveolar lavage fluid (BALF), which occurred in a 21 year old man. Plasma endothelin-1 (ET-1) and interleukin-8 (IL-8) concentration in BALF were elevated on admission, and returned to normal level at recovery, when the pulmonary artery pressure and the PMN counts in BALF were normal. In addition, E-selectin and intercellular adhesion molecule-1 (ICAM-1) in BALF were also slightly increased on admission. These findings suggest that endothelin-1 is a vasoconstrictor which contributes to the pulmonary hypertension in high altitude pulmonary oedema, and that some of the inflammatory mediators play an important role in chemotaxis and accumulation of polymorphonuclear leucocytes in the development of high altitude pulmonary oedema.

Adult↗
PubMed1996

Antagonistic effect of YM022, an antiulcer agent in rats, on human cholecystokinin (CCK)B/gastrin receptor.

We recently isolated a cDNA clone for the human cholecystokinin (CCK)B/gastrin receptor and permanently expressed this receptor cDNA in NIH-3T3 cells. [125I]CCK-8 specifically bound to the membrane of the transfectant, and this binding was displaced by unlabeled CCK-8 with an IC50 of 0.32 nM. Treatment of these cells with CCK-8 increased the intracellular Ca2+ concentration with an EC50 of 0.30 nM. Using these cells expressing functional human CCKB/gastrin receptors, we investigated the pharmacological properties of (R)-1-[2,3-dihydro-1-(2'-methylphenacyl)-2-oxo-5-phenyl-1H-1, 4-benzodiazepin-3-yl]-3-(3-methylphenyl) urea (YM022), a potent and selective CCKB/gastrin receptor antagonist in rats. YM022 potently inhibited [125I]CCK-8 binding to the membrane with an IC50 of 55 pM and CCK-8-induced Ca2+ mobilization with that of 7.4 nM. On the other hand, its racemate and enantiomer more weakly inhibited this binding (IC50 of 110 pM and 11 nM, respectively) and Ca2+ mobilization (IC50 of 18 nM and 94 nM, respectively). These results indicate that YM022 stereoselectively recognizes the human CCKB/gastrin receptor as a potent antagonist and that the established transfectant is useful for characterization of human CCKB/gastrin-receptor ligands.

Animals↗
PubMed1996

Genetic control of urinary deoxyribonuclease I (DNase I) activity levels in mice.

Genetic factors controlling the deoxyribonuclease I (DNase I) activity level were examined in mice. A survey of inbred strains of mice revealed genetic variation in urinary and kidney DNase I activity levels, though a sex difference, males having significantly higher DNase I activity levels than females, was observed in all mouse strains tested. The sex difference in the urinary DNase I activity level was eliminated by testosterone administration to females or gonadectomy to males. The urinary DNase I level was closely correlated to that of the kidneys but no relationship between serum and urinary DNase I activity suggests that the production ratio of DNase I in the kidneys is responsible for strain variation in urinary DNase I levels. Inheritance of quantitative variation of urinary DNase I activity levels was studied by a test cross. The segregation ratio of backcross progenies fitted the model showing that urinary DNase I activity level was controlled by an autosomal single locus, Dna 1 (chi 2 = 0.1053, P > 0.90). The allele Dna 1 ra determines high DNase I inducibility in the kidneys and occurs in BALB/c, C3H/He and A/J strains. The allele Dna 1 rb determines low DNase I inducibility in the kidneys and occurs in DBA/2 and C57BL/6 strains.

Animals↗