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Biomedical subjects

M Shimura

Publications and source records attributed to M Shimura.

At least 37 records · Page 2Linked to original sources
PubMed1999

Cutaneous afferents producing a reflex pupil dilation in anesthetized rats.

Cutaneous afferents producing a reflex pupil dilation were examined using natural mechanical stimulation of the hindlimb skin and electrical stimulation of a sural nerve in anesthetized, artificially ventilated rats. Pupil diameter was continuously recorded after magnification using a microscope connected to a charge coupled device camera. Innocuous brushing, or weak pressing of the skin, did not have any effect on pupil diameter, while pressing the skin more than 720 g/cm2 produced a pressure-dependent pupil dilation. Pinching rather than pressing the skin induced the larger pupil dilation. Electrical stimulation of a sural afferent nerve with weak intensity, which was supra-threshold for Abeta-afferents and sub-threshold for Asigma-afferents, induced a reflex pupil dilation. This dilation continued to increase with further increases in stimulus intensity which involved excitation of Asigma afferents and C afferents. It is concluded that Abeta, Asigma and C afferents in the skin can work as afferents in eliciting reflex pupil dilation in anesthetized rats.

Afferent Pathways↗
PubMed1999

Increased truncated form of plasma tissue factor pathway inhibitor levels in patients with disseminated intravascular coagulation.

To evaluate that the relationship between the truncated form of tissue factor pathway inhibitor (TFPI) and the stage of disseminated intravascular coagulation (DIC), we measured the plasma levels of tissue factor (TF) antigen and the intact and truncated forms of TFPI antigens in 41 patients with DIC, 12 with pre-DIC, and 20 with non-DIC. The plasma TF and total TFPI antigen levels were significantly higher in patients with DIC than in non-DIC patients. Plasma levels of intact TFPI antigen in the pre-DIC groups were significantly lower than in the non-DIC and DIC groups. The truncated form of TFPI antigen levels in DIC patients were significantly increased compared with those in non-DIC and pre-DIC patients. The fact that the intact form of TFPI was decreased in pre-DIC patients compared with that in non-DIC patients, suggests that it is consumed in the pre-DIC state and that hypercoagulability occurs in pre-DIC patients. The increased level of the truncated form of TFPI in DIC patients may be attributed to proteolysis of the intact form of TFPI in these patients. The increased level of the truncated form of TFPI may be a useful index for the diagnosis of DIC.

Disseminated Intravascular Coagulation↗
PubMed1999

Hemostatic molecular markers before the onset of disseminated intravascular coagulation.

We retrospectively measured various hemostatic markers in 240 patients with disseminated intravascular coagulation (DIC) before the onset of DIC and in 110 non-DIC patients, and examined their usefulness for the diagnosis of pre-DIC. Changes in prothrombin time ratio and fibrinogen levels were not significant before the onset of DIC. The plasma levels of fibrinogen and fibrin degradation products before the onset of DIC were increased and the platelet count was gradually reduced in nonleukemic patients; these changes were already significant in the non-DIC state. The plasma levels of thrombin-antithrombin complex (TAT), plasmin-plasmin inhibitor complex (PPIC), D-dimer, and soluble fibrin monomer (sFM) were increased before the onset of DIC. In leukemic patients, the plasma levels of sFM on day 5, those of TAT on day 3, and D-dimer on day 1, were significantly increased before the onset of DIC. The levels of most hemostatic markers 7 days before the onset of DIC were not different from those observed in the non-DIC state. In nonleukemic patients, only D-dimer, sFM, and TAT levels were significantly increased 7 days before the onset of DIC compared with values in the non-DIC state. The positive rate of hemostatic markers for the diagnosis of DIC, TAT, and PPIC were high during the pre-DIC and non-DIC groups. The plasma levels of sFM and D-dimer were low in non-DIC and increased gradually during the pre-DIC state. These findings suggest that hemostatic molecular markers such as sFM, D-dimer, and TAT are useful for the diagnosis of pre-DIC, although their cutoff values were different among various diseases.

Antifibrinolytic Agents↗
PubMed1999

Plasma sFas and sFas ligand levels in patients with thrombotic thrombocytopenic purpura and in those with disseminated intravascular coagulation.

Fas, a member of the tumor necrosis receptor superfamily, is 36 kD surface protein containing a single transmembrane region and induces apoptosis by Fas-Fas ligand binding. Soluble Fas (sFas) is produced as the form lacking 21 amino acid residues containing the transmembrane domain by alternative splicing. We found that the plasma sFas levels of 33 patients with thrombotic thrombocytopenic purpura/hemolytic uremic syndrome (TTP/HUS), 19 patients with disseminated intravascular coagulation (DIC), and 10 non-DIC patients with multiple organ failure (MOF) were significantly higher than those of 21 non-DIC patients without organ failure and those of 25 healthy volunteers. The plasma sFas ligand levels of the TTP/HUS patients, the DIC patients, and the non-DIC patients with MOF were significantly higher than those of the non-DIC patients without organ failure and those of the healthy volunteers. The plasma sFas levels were significantly correlated with the plasma sFas ligand levels in all subjects. The plasma thrombomodulin (TM) levels were increased significantly in the TTP/HUS patients, the DIC patients, and the non-DIC patients with MOF compared with the levels of the non-DIC patients without organ failure and the healthy volunteers. The plasma sFas antigen levels were correlated significantly with the plasma TM levels in all subjects. These findings suggest that the increases of sFas and sFas ligand that cause apoptosis might be related to the vascular endothelial cell injuries in TTP and DIC with organ failure.

Adult↗
PubMed1999

Changes of plasma hemostatic markers during percutaneous transluminal coronary angioplasty in patients with chronic coronary artery disease.

Changes of hemostatic parameters during percutaneous transluminal coronary angioplasty (PTCA) in 75 patients with chronic coronary artery disease were evaluated. Plasma levels of D-dimer, soluble fibrin monomer, plasmin-alpha2 antiplasmin inhibitor complex, and tissue factor (TF) were significantly increased in all patients with chronic coronary artery disease. The activity of antithrombin and protein C and the levels of protein C antigen were significantly decreased 1 hr after PTCA, but they returned to normal range 1 day after PTCA. There was no significant difference in the level of plasma APC-PCI complex before and 1 hr after PTCA. The plasma levels of D-dimer, soluble fibrin monomer, thrombomodulin, TF and PPIC were significantly decreased 1 hr, and the plasma levels of plasmin-alpha2 antiplasmin inhibitor complex 1 day after PTCA. These findings suggest that the decrease of protein C and antithrombin resulted in activation of the coagulation system. One hour after PTCA, the plasma levels of (total-free) TF pathway inhibitor (TFPI) were significantly decreased, but the plasma levels of total and free-TFPI were significantly increased, suggesting that consumption of (total-free) TFPI occurs during PTCA. Overall, these findings suggest that the hypercoagulable state improves during PTCA and that transient decrease of antithrombin, protein C, (total-free) TFPI or plasmin-alpha2 antiplasmin inhibitor complex may cause restenosis of coronary artery.

Angioplasty, Balloon, Coronary↗
PubMed1999

Characterization of a Neurospora crassa photolyase-deficient mutant generated by repeat induced point mutation of the phr gene.

We produced a photolyase-deficient mutant by repeat induced point mutation using the Neurospora crassa photolyase gene cloned previously. This mutation identified a new gene, phr, which was mapped on the right arm of linkage group I by both RFLP mapping and conventional mapping. To investigate the relationship between photoreactivation and dark repair processes, especially excision repair, double mutants of phr with representative repair-defective mutants of different types were constructed and tested for UV sensitivity and photoreactivation. The results show that the phr mutation has no influence on dark repair. Tests with CPD and TC(6-4) photoproduct-specific antibodies demonstrated that the phr mutant is defective in CPD photolyase and confirmed that there is no TC(6-4) photolyase activity in N. crassa. Furthermore, N. crassa photolyase is not a blue light receptor in the signal transduction that induces carotenoid biosynthesis.

Blotting, Southern↗
PubMed1999

Indocyanine green iris angiography of lung carcinoma metastatic to the iris.

BACKGROUND: To investigate the usefulness of indocyanine green (ICG) iris angiography for monitoring vascular abnormalities and the clinical course of metastatic iris tumor during chemotherapy. METHODS: We performed ICG iris angiography at several points during systemic chemotherapy for a 67-year-old man who had been diagnosed as having small-cell carcinoma of the lung with metastatic iris tumors. RESULTS: ICG iris angiography clearly demonstrated hyperfluorescent tumor vessels, rubeosis iridis, and dilated iris stromal vessels. After chemotherapy, these hyperfluorescent vessels and rubeosis regressed. CONCLUSION: ICG iris angiography appears to be an effective and useful method for observing abnormal vessels associated with metastatic iris tumors.

Aged↗
PubMed1999

Quantifying leukocyte dynamics and plugging in retinal microcirculation of streptozotosin-induced diabetic rats.

PURPOSE: To determine leukocyte kinetics in the retinal microcirculation of streptozotosin-induced diabetic rats. METHODS: Rats were made diabetic with intraperitoneal injection of streptozotosin. For one month after injection, the alteration of the velocity and plugging of leukocytes were investigated using acridine orange, which stains leukocytes, and scanning laser ophthalmoscopy. Blood plasma protein levels, such as fibrinogen and alpha1- and alpha2- globulin, were also measured. RESULTS: Throughout the observational period, mean leukocyte velocity was similar between diabetic (1.53+/-0.45 mm/sec) and age-matched control (1.58+/-0.23 mm/sec) rats, but the coefficient of variation of the velocity in the diabetic rats was twice as large as that in the control rats. Plugging was increased in a sigmoidal fashion and saturated for 5 weeks or later. No differences were seen in plasma protein levels between groups. CONCLUSIONS: Within one month of the hyperglycemic condition, the velocities of leukocytes in capillaries were more varied and the leukocytes were plugged time-dependently. This action occurred not because the blood fibrinogen and globulin levels were altered, but because of the leukocyte-endothelium interaction. In streptozotosin-induced diabetic rats, retinopathy usually cannot be found during the fundus examination and fluorescein angiography. In the level of the microcirculation, however, some of the disorders have already occurred.

Acridine Orange↗
PubMed1999

Quantitative analysis of leukocyte dynamics in retinal microcirculation of rats with short-term ischemia-reperfusion injury.

PURPOSE: To characterize the time course of complete recovery of leukocyte velocities in the retinal microcirculation of rats from short-term (5-minute) retinal ischemia. METHODS: After 5 minutes of retinal ischemia produced by clamping the optic nerve, resulting in the occlusion of both central retinal artery and the central retinal vein, we used acridine orange (AO) and a scanning laser ophthalmoscope (SLO) to observe the velocities of leukocytes in precapillary arteriole ( v(a)), capillary (v(c)) and postcapillary venule (v(v)). Measurements were taken at reperfusion time points of 5, 10, 15, 20, 30, 40, 50, 60 and 80 minutes for the ischemic eyes and at 12, 22, 42 and 62 minutes for the control eyes, respectively. RESULTS: Each control velocity was arteriole 25.1 +/- 4.3 mm/ s; venule 16.9 +/- 3.2 mm/s; and capillary 1.54 +/- 0.31 mm/s, respectively. The leukocyte velocities after 5 minutes of ischemia in arteriole and venule recovered completely within 80 minutes of reperfusion; however, the recovery patterns were different. The recovery pattern showed a biphasic increase in arterioles and a monophasic increase in venules. The velocity in capillaries half recovered rapidly, within 5 minutes of reperfusion, but the subsequent recovery was slower and was not complete even at 80 minutes of reperfusion. CONCLUSIONS: In this study, leukocyte velocities in arterioles, venules and capillaries exhibited different recovery patterns following retinal ischemia and subsequent reperfusion. Capillaries, at least within 80 minutes of reperfusion, may have difficulty recovering completely from even short-term (5-minute) ischemia.

Acridine Orange↗
PubMed1999

Micronuclei formation and aneuploidy induced by Vpr, an accessory gene of human immunodeficiency virus type 1.

Vpr, an accessory gene of HIV-1, induces cell cycle abnormality with accumulation at G2/M phase and increased ploidy. Since abnormality of mitotic checkpoint control provides a molecular basis of genomic instability, we studied the effects of Vpr on genetic integrity using a stable clone, named MIT-23, in which Vpr expression is controlled by the tetracycline-responsive promoter. Treatment of MIT-23 cells with doxycycline (DOX) induced Vpr expression with a giant multinuclear cell formation. Increased micronuclei (MIN) formation was also detected in these cells. Abolishment of Vpr expression by DOX removal induced numerous asynchronous cytokinesis in the multinuclear cells with leaving MIN in cytoplasm, suggesting that the transient Vpr expression could cause genetic unbalance. Consistent with this expectation, MIT-23 cells, originally pseudodiploid cells, became aneuploid after repeated expression of Vpr. Experiments using deletion mutants of Vpr revealed that the domain inducing MIN formation as well as multinucleation was located in the carboxy-terminal region of Vpr protein. These results suggest that Vpr induces genomic instability, implicating the possible role in the development of AIDS-related malignancies.

Acquired Immunodeficiency Syndrome↗
PubMed1999

Hemostatic markers in Japanese patients undergoing anticoagulant therapy under thrombo-test monitoring.

The objective of this study was to evaluate several molecular markers of hemostasis in 84 patients with hypercoagulable state, treated with warfarin under thrombo-test (TT) monitoring; TT was expressed as percent of control (TT%). In all patients, the average values of international normalized ratio (INR) of prothrombin time (PT;PT-INR) was 1.68+/-0.49; this increase in PT-INR was not, however, significant in patients under TT% monitoring. There were no thrombotic or severe bleeding complications in these patients during a period of 2 years. Plasma levels of thrombin-antithrombin complex (TAT), plasmin-plasmin inhibitor complex (PPIC), D-dimer, and soluble fibrin monomer (sFM) were slightly increased, suggesting that anticoagulant therapy was not completely effective in our Japanese patients based on the values of TT%. Activated partial thromboplastin time, PT-INR, TT% and protein C activity were significantly correlated with the dose of warfarin; fibrinogen, activated thromboplastin, TAT, PPIC, D-dimer, sFM, protein S and thrombomodulin were not significantly correlated with the dose of warfarin. The PT-INR was negatively correlated with TT%, protein C and protein S, and the correlation between PT-INR and TT-INR was better than that between PT-INR and TT%. The range of TT% was not correlated with the plasma levels of TAT, PPIC, D-dimer or sFM, but the range of PT-INR was correlated with the plasma level of TAT, D-dimer and sFM. The percentage of TAT, D-dimer and sFM within normal range was significantly low in patients with high PT-INR. These finding showed that PT-INR is better than TT% for monitoring the anticoagulant therapy with warfarin, and that TT should be expressed as INR. The values of PT-INR should be more than 1.7 during the anticoagulant therapy with warfarin in Japanese patients with high risk of thrombosis.

Adult↗
PubMed1999

Aberrations of the tissue factor pathway in patients positive for lupus anticoagulant.

To evaluate the relationship between the tissue factor (TF) pathway and lupus anticoagulant (LA), in the present study, we measured the plasma levels of TF antigen and TF pathway inhibitor (TFPI) antigen in patients positive for LA. Plasma TF and TFPI levels in LA-positive patients were significantly higher than levels in healthy volunteers (p < 0.01). In LA-positive patients, there were no significant differences in plasma TF and TFPI levels between patients with and without thrombosis. In patients with thrombosis, there was no significant difference in the plasma TF level between LA-positive and LA-negative patients; however, the plasma TFPI level in LA-positive patients was significantly lower than that in LA-negative patients (p < 0.01). We also examined the TF pathway in human umbilical venous endothelial cells (HUVEC) incubated with plasma of LA-positive patients, LA-negative patients, and healthy volunteers. TF activity was significantly higher (p < .05) in HUVECs incubated with the plasma of LA-positive patients than in cells incubated with the plasma of the other two groups (p < .01). However, there was no significant difference in TFPI antigen levels among the media of HUVECs incubated with the plasma of all groups. The viability of HUVEC incubated with the plasma of LA-positive patients with thromboses, LA-positive patients without thromboses, and LA-negative patients with thromboses were significantly lower than that of HUVECs incubated with the plasma of healthy volunteers (p < .01). These findings suggest that abnormalities of the TF pathway plays an important role in the mechanism of hypercoagulability in LA-positive patients. LA may affect vascular endothelial cells causing thrombogenesis.

Adult↗
PubMed1999

Na+,K+-ATPase activity in cultured bovine retinal pigment epithelium.

PURPOSE: To characterize electrogenic Na+,K+-ATPase activity in cultured bovine retinal pigment epithelium (RPE). METHODS: Cultured bovine RPE cells from passages 3 through 5 were dissociated enzymatically. Na+,K+-adenosine triphosphatase (ATPase)-activated currents (Ip) were measured by using a nystatin perforated-patch recording technique under voltage- clamp conditions. In the presence of suitable blockers for known voltage-dependent Na+, K+, and Ca2+ conductances, the Ip was activated in a concentration-dependent manner by adding K to the external solution. RESULTS: The median effective concentration (EC50) and Hill coefficient for external K+ concentration ([K+]o) were 1.06 mM and 2.55, respectively. The Ip showed no significant voltage dependency. A large outward shift of holding current was observed when [Na+]o, was removed. In the presence of [Na+]o, the addition of K+ to the external solution induced Ip, even when the internal solution did not contain Na+, suggesting the existence of a continuous Na+ influx across the plasma membrane in the presence of [Na+]o,. When Na+ was removed from the external and internal solutions, a transient Ip was observed, indicating that the transient Ip was activated by the intracellular residual Na+. The Ip was concentration-dependently suppressed by ouabain. The 50% inhibitory concentration (IC50) value and Hill coefficient for ouabain were 5.98 microM and 1.12, respectively. CONCLUSIONS: The present study is the first to reported the functional properties of electrogenic Na+,K+-ATPase activity in cultured bovine RPE.

Animals↗
PubMed1998

Cerebrosides A and C, sphingolipid elicitors of hypersensitive cell death and phytoalexin accumulation in rice plants.

When plants interact with certain pathogens, they protect themselves by generating various chemical and physical barriers called the hypersensitive response. These barriers are induced by molecules called elicitors that are produced by pathogens. In the present study, the most active elicitors of the hypersensitive response in rice were isolated from the rice pathogenic fungus Magnaporthe grisea, and their structures were identified as cerebrosides A and C, sphingolipids that were previously isolated as inducers of cell differentiation in the fungus Schizophyllum commune. Treatment of rice leaves with cerebroside A induced the accumulation of antimicrobial compounds (phytoalexins), cell death, and increased resistance to subsequent infection by compatible pathogens. The degradation products of cerebroside A (fatty acid methyl ester, sphingoid base, and glucosyl sphingoid base) showed no elicitor activity. Hydrogenation of the 8E-double bond in the sphingoid base moiety or the 3E-double bond in the fatty acid moiety of cerebroside A did not alter the elicitor activity, whereas hydrogenation of the 4E-double bond in the sphingoid base moiety led to a 12-fold decrease in elicitor activity. Furthermore, glucocerebrosides from Gaucher's spleen consisting of (E)-4-sphingenine and cerebrosides from rice bran mainly consisting of (4E,8E)-4,8-sphingadienine and (4E,8Z)-4,8-sphingadienine showed no elicitor activity. These results indicate that the methyl group at C-9 and the 4E-double bond in the sphingoid base moiety of cerebrosides A and C are the key elements determining the elicitor activity of these compounds. This study is the first to show that sphingolipids have elicitor activity in plants.

Anti-Infective Agents↗
PubMed1998

Room temperature-induced apoptosis of Jurkat cells sensitive to both caspase-1 and caspase-3 inhibitors.

We recently reported that HL-60 cells underwent apoptosis when exposed to room temperature (RT) (21 degrees C). RT-induced apoptosis of HL-60 cells is inhibited by the caspase-1 inhibitor (YVAD-CMK), but not by the caspase-3 inhibitor (DEVD-CHO). In this study, we studied RT-induced apoptosis in 15 human cell lines of hematopoietic lineage and found that the Jurkat cell line also responded to RT by a different apoptotic process. RT-induced apoptosis of Jurkat cells was attenuated by YVAD-CMK as well as DEVD-CHO. Increased caspase activity on DEVD-AMC, which was inhibited by both YVAD-CMK and DEVD-CHO added to the cell culture, was also detected. The involvement of caspase-3 itself, however, was not recognized by Western blot analysis. In contrast, the processing of caspase-3 was observed in the apoptotic HL-60 cells. These data implicate the presence of the redundant processes of apoptosis induced by RT treatment.

Amino Acid Chloromethyl Ketones↗
PubMed1998

Poor outcome in disseminated intravascular coagulation or thrombotic thrombocytopenic purpura patients with severe vascular endothelial cell injuries.

Various hemostatic and vascular endothelial cell markers were measured in patients with disseminated intravascular coagulation (DIC), non-DIC, or thrombotic thrombocytopenic purpura (TTP) and in healthy volunteers to examine the relationships between the hemostatic abnormalities or vascular endothelial cell injuries and the patients' outcomes. Although the plasma levels of soluble fibrin monomer, thrombin-antithrombin complex, plasmin-plasmin inhibitor complex, and D-dimer were significantly increased in the DIC patients, there were no significant differences in these markers between the DIC patients who survived and those who died, suggesting that these markers might not be directly related to the patient outcome. The plasma thrombomodulin (TM) levels in the DIC and TTP patients were significantly higher than those in the healthy volunteers, and the plasma TM levels in the patients who died were significantly higher than those in the patients who survived. These findings showed that the TM level reflected the outcome, and that the outcome of the diseases underlying DIC and TTP might depend on vascular endothelial cell injuries. The plasma protein C and antithrombin activities were markedly reduced in the DIC, non-DIC, and TTP patients who died compared to those who survived. These findings suggest that reduced plasma antithrombin and protein C activities are useful markers of systemic vascular endothelial injuries. Although the plasma tissue factor (TF) levels were significantly increased in the DIC patients, there was no significant difference in the plasma TF levels between the DIC patients who died and those who survived. In conclusion, we found that the outcome of the diseases underlying DIC and TTP is related to vascular endothelial cells, and that plasma TM, antithrombin, and protein C are useful markers for systemic vascular endothelial cell injury.

Antifibrinolytic Agents↗
PubMed1998

Analysis of changes in congener selectivity during PCB degradation by Burkholderia sp. strain TSN101 with increasing concentrations of PCB and characterization of the bphBCD genes and gene products.

We isolated and characterized a gram-negative bacterium, Burkholderia sp. strain TSN101, that can degrade polychlorinated biphenyls (PCBs) at concentrations as high as 150 microg Kaneclor 300/ml, a PCB mixture equivalent to Aroclor 1242. Growing cells of strain TSN101 degraded most of the tri- and tetrachlorobiphenyls in medium containing 25 microg Kaneclor 300/ml. Using PCB concentrations of 50-150 microg of Kaneclor 300/ml, the congener selectivity pattern was different and the pattern of chlorine substitution strongly affected degradation of some congeners. At 25 microg Kaneclor 300/ml, strain TSN101 degraded di- and trichlorinated congeners with chlorine substitutions at both the ortho and the para positions. At higher concentrations of Kaneclor 300, di- and trichlorobiphenyls with ortho substituents in both phenyl rings were not degraded well. Trichlorobiphenyls with para and meta substitutents were degraded equally well at all concentrations studied. The ability of strain TSN101 to degrade ortho and para-substituted congeners was confirmed using a defined PCB mixture with chlorine substituents at 2'- and 4'-positions. A 5-kb DNA fragment containing the bphBCD genes was cloned and sequenced. Comparison of the deduced amino acid sequences of these genes with related proteins indicated 99 and 98% sequence similarity to the BphB and BphD of Comamonas testosteroni strain B-356, respectively. The bphC gene product showed 74% sequence similarity to the BphC of Burkholderia cepacia strain LB400 and exhibited a narrow substrate specificity with strong affinity for 2, 3-dihydroxybiphenyl. A bphC-disrupted mutant of Burkholderia sp. strain TSN101, constructed by gene replacement, lost the ability to utilize biphenyl, thus supporting the role of the cloned bph gene in biphenyl metabolism.

Aroclors↗