Biomedical subjects

K Toda

Publications and source records attributed to K Toda.

At least 109 records · Page 6Linked to original sources

PubMed1996

The cytocidal activity of OK-432-activated mononuclear cells against human glioma cells is partly mediated through the Fas ligand/Fas system.

We have been applying an adoptive immunotherapy protocol to patients with malignant brain tumors using OK-432-activated peripheral blood mononuclear cells (OK-MCs). In order to elucidate the mechanism of OK-MCs' cytotoxicity, we examined the expression of Fas ligand mRNA in OK-MCs and the cytocidal activity of these cells against a human glioma cell line, T98G which expresses a high level of Fas. The expression of Fas ligand mRNA was low in non-treated peripheral blood mononuclear cells and was elevated by treatment with OK-432, irrespective of the dose employed. Apoptosis of T98G cells induced by OK-MCs was unequivocally inhibited by the pretreatment of T98 G cells with ZB4 monoclonal antibody, which binds to Fas and blocks the binding of Fas ligand to Fas. These data indicate that the cytotoxic activity of OK-MCs via apoptosis seems to be at least partly mediated by the Fas ligand/Fas system. Adoptive immunotherapy using the Fas ligand/Fas system could be a new treatment modality for human malignant brain tumors.

Adjuvants, Immunologic↗

PubMed1996

Reversal of altered intestinal mucosal immunity in rats fed elemental diet by supplementation of oleic acid.

We have previously demonstrated that elemental diet (ED) induces decreased lymphocyte transport in intestinal lymph and significant changes in T cell subsets and the number of IgA-containing cells in gut-associated lymphoid tissues of rats. In order to examine whether the low fat content contributes to the induction of immunological changes in gut-associated lymphoid tissues, the effects of additional fatty acid in the ED were investigated. Rats were divided into four groups: elemental diet alone, elemental diet supplemented with 5% oleic acid (OA), elemental diet with 10% OA and conventional diet as a control. These diets were given at the same daily calorie intake for 4 weeks. The flow rate of intestinal lymph showed no significant difference between the four groups. However, lymphocyte flux as well as the percentage of CD3+ and CD4+ cells were significantly greater in the control and the 10% OA groups than in the ED and 5% OA groups. Intestinal lymph showed decreased concentrations of IgG and IgA in the ED group, whereas the addition of 10% OA significantly attenuated the decrease in these levels. In mesenteric lymph nodes, the CD4+/CD8+ ratio was significantly decreased in the ED group, but 10% OA reversed this change. Immunohistochemical analysis of the ileal mucosa showed that in the ED group the population of CD4+ cells was decreased, while the number of CD8+ cells was increased. Supplementation of OA to ED produced similar stepwise attenuation of the changes in lymphocyte subpopulations in the lamina propria, while the 10% OA group reached levels that were not statistically different from controls. In the elemental diet group, there was a significant decrease in immunoglobulin-containing cells of the IgA class in the lamina propria of the intestine. Similarly, the addition of OA induced dose-dependent recovery in the number of IgA-containing cells. These results suggest that a low dietary concentration of fat may be closely related to changes in lymphocyte transport in intestinal lymph and mucosal immunity of intestinal mucosa induced by the feeding of a long-term ED.

Animals↗

PubMed1996

Influence of ventricular fibrillation on sympathetic nerve activity under biventricular bypass circulation.

Autonomic nerves play an important role in circulatory control. The characteristics of sympathetic nerve activity (SNA) during artificial circulation, however, are not well understood. In this study, we examined the influence of natural heart beating on the renal SNA (RSNA) using pulsatile 100% biventricular assistance and electrically induced ventricular fibrillation in anesthetized goats, whose heart rate and size are similar to the human heart's. Following induction of the ventricular fibrillation, the pulse-synchronous discharges in the RSNA did not change their periodicity and quantity significantly. It was concluded that the beating of the heart had little influence on the RSNA and was presumably not essential for maintaining nervous control of circulation as long as the circulation was maintained by an artificial heart.

Animals↗

PubMed1996

A volume-controlled liquid ventilator with pressure-limit mode: imperative expiratory control.

Liquid ventilation with perfluorocarbon (PFC) has been considered to offer advantages over gas ventilation to respiratory distress syndrome patients. We developed a volume-controlled liquid ventilator with pressure-limit mode; inspiration is performed mechanically with an actuator under the preset limit of the intratracheal pressure (Paw); expiration is performed by gravity assistance. Oxygenation and CO2 removal of PFC are done with a membrane oxygenator. An endotracheal tube with a Paw monitor line was placed in 5 rabbits weighing 2.7 +/- 0.6 kg, and liquid ventilation was conducted with the condition that the upper and lower limits of Paw were 20 and -20 mm Hg, respectively. The best arterial pH and gas tension were examined. The averaged arterial pH and gas tension were examined. The averaged arterial pH. Pao2, Paco2, and Sao2 were 7.45 mm Hg, 369 mm Hg, 46.2 mm Hg, and 100% at the best values, respectively. Ventilatory conditions at the best values were as follows: ventilation rates, tidal volume peak Paw, average Paw, and trough Paw were 5-15 (11 +/- 4) times/min, 13.3-17.3 (15.6 +/- 1.4) ml/kg, 5-18 (12 +/- 5) mm Hg, -7-4 (-1 +/- 4) mm Hg, and -20(-)-6 (-13 +/- 5) mm Hg, respectively. Pressure-limit control of the system worked well, but in the initial 3 animals, fluorothrax, that is the leakage of PFC into thoracic cavity, was recognized at the Paw from 20 to 25 mm Hg after the upper pressure limit was raised to 25 mm Hg to improve Paco2. The fluorothrax seemed to be caused by excess end-expiratory residual volume. An expiratory control mechanism appears to be imperative for further improvement of our liquid ventilator.

Animals↗

PubMed1996

Sympathetic nerve activities in pulsatile and nonpulsatile systemic circulation in anesthetized goats.

To investigate the effects of pulsatile and nonpulsatile systemic circulation on the sympathetic nerve activity, using a left heart bypass technique, we converted systemic circulation between the pulsatile and the nonpulsatile mode in anesthetized goats and analyzed differences in periodicity and quantity of renal nerve activity (RNA). After pulsatile systemic circulation was converted to the nonpulsatile mode, the mean RNA was significantly increased from 10.7 +/- 3.6 to 13.1 +/- 3.4 microV and periodic discharges of RNA, which corresponded to pulse-related rhythm during pulsatile circulation, became obscure, whereas an 8-12 cycle/s rhythm, which was distinguished and accounted for 30 +/- 9% of total intervals during pulsatile circulation, became dominant (48 +/- 11%). These results clarified a significant increase in mean RNA after depulsation of the systemic circulation and indicated that the cardiac-related rhythm in RNA could be produced by periodic inputs from arterial baroceptors alone, whereas the 8-12 cycle/s rhythm that was present regardless of the type of circulation was the fundamental rhythm originating from the vasomotor center.

Animals↗

PubMed1996

Ipsilateral hemiplegia caused by right internal capsule and thalamic hemorrhage: demonstration of predominant ipsilateral innervation of motor and sensory systems by MRI, MEP, and SEP.

A patient with a right internal capsule and thalamic hemorrhage showed ipsilateral hemiplegia. MRI at 10 months after the cerebral hemorrhage demonstrated Wallerian degeneration, which could be traced to the ipsilateral anterior funiculus at the cervical level. The findings of motor evoked potentials and somatosensory evoked potentials indicate a predominantly ipsilateral innervation of motor and sensory systems in this particular patient.

Cerebral Hemorrhage↗

PubMed1996

[Expression of apoptosis-related gene products in human brain tumors and apoptosis-inducing therapy].

To elucidate the mechanism of apoptosis in brain tumors, we analyzed the expression of apoptosis-related gene products in cultured glioma cells and biopsied brain tumor specimens. Fas, Bcl-2 family (Bcl-2, Bcl-x and Bax) and ICE family (ICE, Ich-1) were found to be involved in tumorigenesis of certain brain tumors. It was also clarified that OK-432 activated mononuclear cells could kill T98G glioblastoma cells by apoptotic mechanism through the Fas ligand/Fas system.

Apoptosis↗

PubMed1996

Development of a centrifugal pump with improved antithrombogenicity and hemolytic property for chronic circulatory support.

A centrifugal pump with a unique structure has been developed for chronic support. The pump is driven by a magnetic coupling and has no rotating shaft, no seal around the rotating part, and a balancing hole at the center of the impeller and the thrust bearing. The pump was improved in stepwise fashion to realize good antithrombogenicity and low hemolysis. The first pump, the National Cardiovascular Center (NCVC)-0, had an impeller with 4 rectangular and curved vanes; 6 triangularly shaped curved vanes were employed in the second model, the NCVC-1, to reduce trauma to the blood. In the third design, the NCVC-2, the central hole was enlarged, and the thrust bearing shoulder was rounded so that blood washing was enhanced around the impeller; stream lines also were smoothed for improved antithrombogenicity. The hemolytic property of the device was evaluated in vitro with heparinized fresh goat blood; hemolysis indexes of the NCVC-0, -1, and -2 were 0.05, 0.01, and 0.006 g per 100 L, respectively. Antithrombogenicity of the pumps was examined in animal experiments as a left heart bypass device in goals weighing 52-75 kg. Six NCVC-0 pumps were driven for 14 to 33 (22.0 +/- 7.6) days in goats receiving the antiplatelet drug cilostazol orally. Four NCVC-1 pumps ran for 1 to 80 (28.5 +/- 30.6) days with the same drug regimen in 2 cases and with no anticoagulation therapy in 2 cases. After 3 preliminary 1-week tests of NCVC-2 pumps in animals, the pump was installed in 3 goats; 2 pumps were still running on the 182nd and 58th pumping day. Intracorporeal implantation also was attempted successfully. The results indicate that this pump has promising features for chronic support although longer term and additional evaluations are necessary.

Animals↗

PubMed1996

Tandem operation of a turbo blood pump (BP-80--type centrifugal pump) to reduce hemolysis.

When operating turbo blood pumps in tandem, the strength of shear stress is reduced, but the exposure duration of the stress is increased. The purpose of this experiment was to compare the degree of contribution of these two factors on hemolysis as well as to evaluate the effectiveness of the tandem operation of turbo blood pumps. Tandem operation of two Bio-pumps (BP-80; Medtronics Bio-medicus, Inc., Eden Prairie, Minnesota, U.S.A.) were compared with single operation of a BP-80 in in vitro hemolysis tests in three different driving conditions, that is, pumping heads of 200, 350, and 500 mm Hg under a pump flow rate of 5 L/min. The Allen's hemolytic indexes of the tandem operation at pumping heads of 200, 350, and 500 mm Hg were 0.014, 0.020, and 0.080 mg/dl, respectively. The hemolytic indexes of the single operation at pumping heads of 200, 35, and 500 mm Hg were 0.014, 0.056, and 0.12 mg/dl, respectively. These results indicate that tandem operation is a useful method of reducing hemolysis with the BP-80 under high pumping heads and that the effect on hemolysis of exposure to higher shear stresses may be more serious than that of longer durations of exposure to shear stress in turbo blood pumps.

Animals↗

PubMed1996

Injury to a duplicated cystic duct during laparoscopic cholecystectomy.

Duplication of the cystic duct is a rare variation of the biliary system. It is important to pay attention to this variation to avoid intraoperative biliary system injury, especially during laparoscopic cholecystectomy. In a 66-year-old woman with gallstones, endoscopic retrograde cholangiopancreatography (ERCP) revealed no anomaly of the biliary system. At laparoscopic cholecystectomy, although intraoperative cholangiography demonstrated the second cystic duct, we misdiagnosed the duplication of cystic duct because preoperative ERCP had demonstrated normal anatomy. It was thought that the second cystic duct was dissected during the operation and the patient suffered from postoperative bile leakage. After reoperation, the patient recovered well. The diagnostic and therapeutic problems of such an anomaly are discussed below with the review of the literature.

Aged↗

PubMed1996

Aphidicolin uncouples the chloroplast division cycle from the mitotic cycle in the unicellular red alga Cyanidioschyzon merolae.

The unicellular red alga Cyanidioschyzon merolae possesses one chloroplast, one mitochondrion, and one cell nucleus. Since the division of these organelles and cytokinesis occur in a coordinated manner, mitosis and the organelle division cycles must be tightly coupled. We report here that aphidicolin, a specific inhibitor of DNA polymerase alpha, uncouples the chloroplast division cycle from the mitotic cycle. The effects of aphidicolin on C. merolae cells were examined by both epifluorescence and electron microscopy. When cells at the S phase in synchronous culture were treated with aphidicolin, mitosis and cytokinesis did not occur, while chloroplast division did. Moreover, both of the chloroplasts in these cells continued to divide and then generated four or more chloroplasts per cell. The inhibition of cell-nuclear DNA synthesis by aphidicolin was confirmed using microfluorometry. In addition, microfluorometry revealed that the total size and the amount of DNA in chloroplasts in aphidicolin-treated cells remained constant during uncoupled chloroplast division. As a result, the size and amount of DNA per chloroplast decreased stepwise during chloroplast division. Electron microscopic examination of aphidicolin-treated cells showed that the second division of chloroplasts uses a chloroplast-dividing ring similar to that in cells undergoing normal chloroplast division. These results suggest that chloroplast division by the dividing ring is free from a checkpoint control that inhibits the progression of mitosis and cytokinesis in the absence of the completion of cell-nuclear DNA synthesis, and also that chloroplasts lack a checkpoint control mechanism that inhibits its division without growth or DNA synthesis of itself.

Aphidicolin↗

PubMed1995

Classic steroid 11 beta-hydroxylase deficiency caused by a C-->G transversion in exon 7 of CYP11B1.

Steroid 11 beta-hydroxylase deficiency (11 beta OHD) is derived from mutations in the P45011 beta gene (CYP11B1) and inherited in an autosomal recessive manner. In the present study, we have performed a molecular genetic analysis of CYP11B1 in a Japanese patient clinically diagnosed as classic 11 beta OHD. Nucleotide sequencing of the PCR-amplified exons from the patient's genomic DNA reveals a unique C-->G transversion that converts codon 384 CGA (arginine) to GGA (glycine) in exon 7. Restriction fragment length polymorphism (RFLP) data demonstrate that the patient is homozygous for this mutation. When the full-length cDNA corresponding to CYP11B1 of the patient is transfected into COS-7 cells, no steroid 11 beta-hydroxylase activity is detectable in mitochondria of the cells. These results indicate that this point mutation completely abolishes P45011 beta activity and causes the classic 11 beta OHD.

Adolescent↗

PubMed1995

A SP1 binding site in the GC-rich region is essential for a core promoter activity of the human endothelial nitric oxide synthase gene.

Endothelial nitric oxide synthase (eNOS) is an important oxygenase which catalyzes the conversion of L-arginine to L-citrulline to form nitric oxide (NO), a potent important factor for vasodilation and inhibition of platelet aggregation. We have analyzed characteristics of the promoter region of the human eNOS gene using the transient expression in human endothelial cells of CAT constructs with a series of 5'-deletion mutants. The 5'-flanking region between -116 and -98, which contains a putative consensus sequence for binding of transcription factor Sp1, is essential to direct a basal promoter activity. Gel mobility shift analysis involving anti-Sp1 antibody and competitor DNAs disrupted at the binding site for Sp1 reveals that Sp1 or its closely related protein(s) binds to the consensus sequence located between -104 and -96. These results indicate that the Sp1 site is essential for a core promoter activity of the human eNOS gene.

Base Composition↗

PubMed1995

Identification of a transcriptional regulatory factor for human aromatase cytochrome P450 gene expression as nuclear factor interleukin-6 (NF-IL6), a member of the CCAAT/enhancer-binding protein family.

Human aromatase cytochrome P450 catalyzes the ultimate reaction in the estrogen biosynthetic pathway by coupling with another enzyme, NADPH-cytochrome P450 reductase, in the endoplasmic reticulum. The expression of the gene encoding the enzyme (CYP19) is regulated, in part, by tissue-specific promoters through the use of alternative-splicing mechanisms. Recently, we have localized a transcriptional activating element at positions -2141 to -2115 relative to the major cap site of the gene, by transient expression analyses in human BeWo choriocarcinoma cells using the bacterial chloramphenicol acetytransferase reporter gene ligated with CYP19 promoter sequences which regulate expression in this tissue. Here, we report the isolation of a cDNA encoding a DNA-binding protein which binds specifically to the regulatory element. The deduced amino-acid sequence of the insert is identical to that corresponding to the DNA-binding domain and the dimerization domain of a transcription factor, nuclear factor interleukin-6 (NF-IL6), a member of the CCAAT/enhancer-binding protein (C/EBP) family. Studies using specific antibodies against members of the C/EBP family demonstrate that NF-IL6 is the major nuclear factor binding to the regulatory element in BeWo cells; nevertheless. C/EBP alpha also seems to be involved. Disruption of the NF-IL6-binding site within the regulatory element resulted in the disappearance of the transcriptional enhancing activity of the element, indicating that NF-IL6 is at least one of the nuclear factor(s) which enhances transcription through binding to the cis-acting element. These results indicate the intrinsic importance of NF-IL6 in the transcriptional regulation of CYP19 expression.

Amino Acid Sequence↗

PubMed1995

Comparison of the phosphorylation of myelin-associated glycoprotein in cultured oligodendrocytes and Schwann cells.

Phosphorylation of the large and small isoforms of myelin-associated glycoprotein (L- and S-MAG) was investigated in primary oligodendrocyte cultures and in immortalized Schwann cells by incubating the cells with inorganic [32P]phosphate and immunoprecipitating MAG. In oligodendrocytes, both L- and S-MAG were phosphorylated, but L-MAG was much more heavily labeled. In Schwann cells, most of the phosphorylation was in S-MAG, which is the predominant isoform expressed by these cells. In both types of cells, the principal phosphorylated amino acid in MAG was serine. Radioactive phosphothreonine and phosphotyrosine were also detected in the MAG from oligodendrocytes. In Schwann cells, there was less phosphorylation of threonine and labeled phosphotyrosine was not detected. In both oligodendrocytes and Schwann cells, the phosphorylation of MAG was stimulated by phorbol ester and a calcium ionophore, but not by forskolin. The results indicate that the phosphorylation of MAG is catalyzed by protein kinase C and possibly other calcium-activated kinases in both types of myelinating cells, but not by cAMP-activated kinase. An inhibitor of tyrosine phosphatase, ammonium vanadate, increased the amount of radioactive phosphate in MAG several fold in both oligodendrocytes and Schwann cells. However, even in the presence of vanadate, the great majority of radioactivity in MAG was in phosphoserine and only a small amount was in phosphotyrosine, suggesting that tyrosine phosphorylation of other proteins may indirectly increase the phosphorylation of MAG. The current status of our understanding of MAG phosphorylation is reviewed in the context of similarities and differences between our results and other reports in the literature.

Animals↗

PubMed1995

Induction of ADF/TRX by oxidative stress in keratinocytes and lymphoid cells.

Adult T-cell leukemia-derived factor (ADF)/human thioredoxin (TRX) has thiol-dependent reducing activities and is known to have regulatory roles on the DNA-protein interaction and cell activation. Inducive effect of ultraviolet (UV) has been indicated because of the enhanced expression of ADF/TRX in epidermal cells of sun-exposed skin, as determined by immunohistochemical staining with antibody against recombinant ADF (rADF). We studied the effect of UVB irradiation and other oxidative stress on the expression of ADF/TRX in epithelial cells as well as lymphoid cells, as HTLV-1 and Epstein-Barr virus-transformed lymphoid cells constitutively produce ADF/TRX. Using immunohistochemical staining anti-ADF antibody, the enhancement of ADF/TRX expression on primary culture of human keratinocytes was demonstrated, 12 h after 20 mJ/cm2 UVB irradiation. Western blot analysis of the ADF/TRX protein in the cell lysates also showed the significant induction. In in situ hybridization, induction of ADF/TRX mRNA was detected after 4 h of UV exposure. ADF/TRX was also induced in a HTLV-1 (+) T-cell line, MT-1, by UVB or H2O2 dose dependently. The augmentation of ADF/TRX was observed 6 h after treatment of H2O2.

Blotting, Western↗

PubMed1995

Transcriptional regulation of the human aromatase cytochrome P450 gene expression in human placental cells.

The human aromatase cytochrome P450 gene, CYP 19, spans more than 75 kb in the human genome. Recently, it is proposed that the expression of the CYP 19 gene is regulated in part by tissue-specific promoters through the use of mechanisms involving alternative splicing of a number of untranslated exons. In this study, we have characterized cis-acting elements involved in the transcriptional regulation of the gene in human placental cells, where the majority of the transcripts contain the 5'-untranslated sequence encoded by exon I.1. By transient expression analyses in human BeWo choriocarcinoma cells using the bacterial chloramphenicol acetyltransferase gene as a reporter gene, we localized an enhancer element in the region between -242 and -166 relative to the major cap site of the gene. Furthermore, we demonstrate that the element between -2141 and -2115 participates in the 12-O-tetradecanoylphorbol 13-acetate (TPA)-mediated enhancement of gene expression. By screening a human placental cDNA expression library, we have isolated a cDNA clone (lambda 1-2) encoding a peptide which binds specifically to the element between -2141 and -2115. Sequence analysis of the clone revealed that the insert of lambda 1-2 encodes a part of the amino acid sequence of NF-IL6 (also termed as LAP and C/EBP beta). Northern blot analysis reveals expression of the NF-IL6 gene in BeWo cells and human placenta. These results indicate that NF-IL6 is one of the nuclear factors which participate in TPA-mediated transcriptional enhancement of CYP 19 gene expression.

Amino Acid Sequence↗

PubMed1995

Long loops in proteins.

In proteins, loop regions which connect secondary structures are generally short (80% are <10 amino acids long). However, long loops, defined here as > or = 10 residues, do occur. Two types of long loop may be distinguished: those which connect adjacent regions of secondary structure ('long-closed') and those which connect distant secondary structures ('long-open'). Only 5% of all loops in proteins fall into the long-open class. Inspection of these unusual long-open loops reveals a higher percentage of proline residues and more helix-helix linkages than expected. Exposure to solvent is similar for long-open and long-closed loops. The role of these loops in protein folding is discussed.

Amino Acid Sequence↗