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Biomedical subjects

T Kondo

Publications and source records attributed to T Kondo.

At least 649 records · Page 36Linked to original sources
PubMed1996

Response of tracheal smooth muscle tone to lower brain stem hypoxia in dogs.

We examined effects of central hypoxia on tracheal smooth muscle (TSM) tone, phrenic nerve activity (PNA) and blood pressure (BP) in decerebrated, paralysed, and artificially ventilated dogs. Central hypoxia was induced by injection of N2-saturated saline (5 ml; PO, 25-32 torr) through a catheter in the vertebral artery. The effects of central hypoxia were compared with the responses to central chemoreceptors stimulation, namely central hypercapnia induced by intravertebral injection of high CO2 saline (5 ml; PCO2 90-100 torr, PO2 80-120 torr, pH 7.38-7.42) buffered by HCO3-. Central hypoxia caused relaxation of TSM accompanied by depression of PNA and elevation of BP. In contrast, central hypercapnia evoked tracheal constriction along with respiratory excitation and pressor response. The tracheal relaxation in response to central hypoxia occurred with onset and peak latencies similar to those observed in PNA depression and BP elevation. This suggests a common source for the synaptic inputs to three distinct control systems involved in cardiovascular, respiratory and airway functions. Such neuronal substrate is considered to be activated by central hypoxia.

Animals↗
PubMed1996

Differential response in the release of hydrogen peroxide between astroglial cells and endothelial cells following hypoxia/reoxygenation.

Hydrogen peroxide (H2O2) and lactate dehydrogenase (LDH) released from cultured astroglial cells (AGs) and brain endothelial cells (BECs) were measured following hypoxia/reoxygenation. AGs released H2O2 to the extracellular space from 8 h of hypoxia with the cellular injury indicated by LDH increase. In contrast, BECs released H2O2 at 4 h of hypoxia, prior to the LDH increase. These results suggest that AGs and BECs play different roles in production and metabolism of oxygen free radicals in the blood-brain barrier (BBB), and AGs may protect the BBB disruption from oxidative stress after hypoxia/reoxygenation.

Animals↗
PubMed1996

bcl-2 protein is increased in the brain from parkinsonian patients.

The proto-oncogene bcl-2 is involved in the regulation of cell death and may be able to block apoptosis in neurons through reduced generation of reactive oxygen species (ROS). The bcl-2 product was measured for the first time in brain (caudate nucleus, putamen and cerebral cortex), ventricular cerebrospinal fluid (VCSF), and lumber CSF (LCSF) from control and parkinsonian patients by highly sensitive two-site sandwich enzyme-linked immunosorbent assay (ELISA). The concentrations of bcl-2 in the nigrostriatal dopaminergic regions were significantly higher in parkinsonian patients than those in controls, whereas this product in cerebral cortex showed no significant difference between parkinsonian and control subjects. Neither VCSF nor LCSF from control or parkinsonian subjects contained the bcl-2 product in the detectable amount (< 5 U/ml). Since oxidative stress may be involved in neurogenerative disorders, accumulation of bcl-2 may reflect a mechanism for counterbalancing ROS-mediated damage, or it might represent the impairment of bcl-2-dependent protection from ROS in parkinsonian brain.

Aged↗
PubMed1996

Involvement of transcription factor encoded by the mi locus in the expression of c-kit receptor tyrosine kinase in cultured mast cells of mice.

The mi locus of mice encodes a member of the basic-helix-loop-helix-leucine zipper (bHLH-Zip) protein family of transcription factors (hereafter called MITF). Cultured mast cells of mi/mi genotype (mi/mi CMCs) did not normally respond to stem cell factor (SCF), a ligand for the c-kit receptor tyrosine kinase. The poor response of mi/mi CMCs to SCF was attributed to the deficient expression of c-kit both the mRNA and protein levels. The purpose of the present study is to investigate the effect of MITF on the transcription of the c-kit gene. First, we introduced cDNA encoding normal (+) MITF or mutant (mi) MITF into mi/mi CMCs using the retroviral vector. Overexpression of (+)-MITF but not mi-MITF normalized the expression of the c-kit and the poor response of mi/mi CMCs to SCF, indicating the involvement of (+)-MITF in the c-kit gene transactivation. Second, we analyzed the promoter of the c-kit gene. Three CANNTG motifs recognized by bHLH-Zip-type transcription factors were conserved between the mouse and human c-kit promoters. Among these three CANNTG motifs, only the CACCTG motif (nt -356 to -351) was specifically bound by (+)-MITF. When the luciferase gene under the control of the c-kit promoter was contransfected into NIH/3T3 fibroblasts with cDNA encoding (+)-MITF or mi-MITF, the luciferase activity significantly increased only when (+)-MITF cDNA was cotransfected. The deletion of the promoter region containing the CACCTG motif or the mutation of the CACCTG to CTCCAG abolished the transactivation effect of (+)-MITF, indicating that (+)-MITF transactivated the c-kit gene through the CACCTG motif. When the luciferase gene under the control of the c-kit promoter was introduced into the FMA3 mastocytoma and FEC-P1 myeloid cell lines, remarkable luciferase activity was observed only in FMA3 cells. Thus, the involvement of (+)-MITF in the c-kit transactivation appeared to be specific to the mast cell lineage.

Animals↗
PubMed1996

Induction of chemokine gene expression during allogeneic skin graft rejection.

The factors mediating trafficking of alloantigen-primed T cells and mononuclear phagocytes to the site of an allograft during the graft rejection process remain largely undefined. Based upon their demonstrated chemoattractant properties, chemokines may play a role in directing inflammatory cells to graft sites and initiate rejection. To begin to investigate the role of chemokines in graft rejection, we used Northern blot analysis to examine the temporal expression of 6 chemokine genes in murine allogeneic skin grafts disparate at the entire MHC and minor antigens and grafts with a disparity at either single class I or class II MHC determinants. Two general patterns of chemokine gene expression in each of the allografts were observed. Intragraft expression of 1 group of chemokine genes, including macrophage inflammatory protein-1alpha (MIP-1alpha), MIP-1beta, JE, and KC was observed at peak levels 3 days posttransplant in each of the 3 different allograft models. Expression of these genes in control isografts was at low levels, with the exception of JE, which was expressed at equivalent levels in all iso- and allografts for the first 4-5 days posttransplant, and KC, which was expressed at equivalent levels in C57BL/6 isografts and bm1 and bm12 allografts. A second group of chemokine genes, including RANTES (regulated upon activation normal T cell expressed and secreted) and IP-10 (interferon-gamma inducible protein), was expressed at low levels at early times after transplantation but at high levels 3-4 days before rejection of the allografts was complete. Isograft expression of RANTES and IP-10 was undetectable at the late time points. The results suggest that these 2 patterns of chemoattractant cytokine gene expression may be representative of the early inflammatory and the late T cell-mediated phases of the allograft rejection process, respectively.

Animals↗
PubMed1996

Long exposure to high glucose concentration impairs the responsive expression of gamma-glutamylcysteine synthetase by interleukin-1beta and tumor necrosis factor-alpha in mouse endothelial cells.

To elucidate the pathological metabolism of glutathione synthesis in diabetic endothelial cells, we studied the expression of gamma-glutamylcysteine synthetase (gamma-GCS) using a mouse vascular endothelial cell line. Exposing normoglycemic endothelial cells to tumor necrosis factor-alpha (TNF-alpha) or interleukin-1beta (IL-1beta) increased the activity and the mRNA expression of gamma-GCS. The addition of inhibitors for nuclear factor kappaB (NF-kappaB) to the cells caused a loss of the gamma-GCS mRNA expression in response to TNF-alpha. A shift of the concentration of glucose in the medium from 5.5 to 28 mM glucose and a following incubation for 7 days decreased the expression of gamma-GCS mRNA. These cells showed no apparent responses of gamma-GCS mRNA or the activity of NF-kappaB to TNF-alpha or IL-beta. Increase in the GSH concentration of the cells treated with 28 mM glucose restored the expression of gamma-GCS mRNA and its response to TNF-alpha or IL-beta, suggesting that redox regulation is involved in the expression of gamma-GCS. In summary, the expression of gamma-GCS is regulated by TNF-alpha or IL-1beta in endothelial cells mediated by NF-kappaB stimulation, and impairment of the regulation of gamma-GCS in hyperglycemic cells may be a cause of medical complications that develop in diabetes mellitus.

Adenosine Triphosphate↗
PubMed1996

Relation of oxidative stress and glutathione synthesis to CD95(Fas/APO-1)-mediated apoptosis of adult T cell leukemia cells.

An IL-2 dependent adult T cell leukemia cell line (SO4) has been established that is sensitive to CD95-mediated apoptosis as well as a subline (R-SO4) that is resistant. Incubating SO4 cells with anti-CD95 IgM mAb caused concentration-dependent cell death. On the contrary, R-SO4 cells did not die even at 1000 ng/ml of anti-CD95 IgM mAb. The levels of CD95 expression on R-SO4 cells were one-third of those on SO4 cells. However a blocking Ab, anti-CD95 IgG mAb, did not induce complete resistance of SO4 cells to anti-CD95 IgM mAb as R-SO4 cells. As CD95 and TNF receptor are similar, and TNF/TNF receptor binding induces oxygen radicals, the involvement of oxidant and antioxidant systems in CD95-mediated apoptosis has been examined. The addition of anti-CD95 IgM mAb resulted in formation of intracellular oxygen radical species in the SO4 cells as measured using 2',5',-dichlorofluorescein as substrate. The oxygen radical production induced DNA damage as determined by formation of 8-hydroxydeoxyguanosine. No increase in the formation of oxygen radicals was observed in R-SO4 cells. Concentrations of the intracellular antioxidant, glutathione, and the key enzyme for its synthesis, gamma-glutamylcysteine synthetase, were 150% increased in R-SO4 cells in comparison with that of SO4 cells. Moreover, glutathione ester decreased the formation of 8-hydroxydeoxyguanosine. These results suggested that apoptosis mediated by CD95 in ATL cells is related to the production of oxygen radical species and cellular antioxidant systems, especially, glutathione synthesis.

Apoptosis↗
PubMed1996

Mutation in p53 and de-regulation of p53-related gene expression in three human cell lines immortalized with 4-nitroquinoline 1-oxide or 60Co gamma rays.

In vitro models of malignant transformation of human cells may provide considerable insight into the mechanisms of multi-step carcinogenesis. It is well established that normal human cells must be immortalized before they can be malignantly transformed; however, they are stringently destined for aging and are rarely immortalized. The mechanism of cellular aging and immortalization is still unknown. We detected expression of only mutated p53 mRNA by direct sequencing of the reverse-transcribed mRNA in 3 human cell lines immortalized either with 4-nitroquinoline 1-oxide or with 60Co gamma rays. Consequently, only the mutated pS3 protein was expressed in each immortalized cell line. The expression of sdiI/p21 and mdm2, both of which are positively regulated by wild-type p53, was significantly down-regulated in the immortalized cell lines, resulting in over-expression of cdk2 and cdk4. Introduction of the sdiI/p21 gene into these cells was followed by a remarkable decrease in their ability to synthesize DNA. These results indicate that the p53 cascade may play an important role in the immortalization of human cells.

4-Nitroquinoline-1-oxide↗
PubMed1996

Embryonic genes expressed in Alzheimer's disease brains.

Alzheimer's disease (AD)-specific or characteristic gene expression was explored by the identification of cDNA clones by means of differential screening for embryonic brain cDNA library with 32P-labeled cDNA probes prepared from mRNA of AD and normal human brains. To isolate neuronal genes in degenerating neurons, we used rat embryonic cDNA library at stage day 15 when glial cells developed poorly in the brain. Seventeen embryonic genes were identified as embryonic alpha-tubulin, embryonic beta-tubulin, hnRNP, protein L-isoaspartyl methyltransferase (PIMT), ferritin heavy chain, type IV collagen, actin-binding protein cofilin, profilin and nine novel sequences designated as A1-9. We characterized these genes by Northern blot analysis, RNase protection assay and immunohistochemical studies, showing that PIMT and a novel gene designated as A5 showed the transcriptional up-regulation in AD brains. In addition, the immunohistochemical studies showed PIMT, type IV collagen, and cofilin were associated with neurofibrillary tangles in degenerating neurons, brain vessels in affected regions, and synaptosomal structures in AD brains, respectively. The catalogue presented here also showed the involvement of cytoskeletal proteins, cytoskeleton-associated proteins, and an iron-storage protein, suggesting the presence of regenerating activity and the abnormal metabolisms in affected neurons of AD brains.

Alzheimer Disease↗
PubMed1996

A sigma factor that modifies the circadian expression of a subset of genes in cyanobacteria.

We isolated mutants affected in the circadian expression of the psbAI gene in Synechococcus sp. strain PCC 7942 using a strategy that tags the genomic locus responsible for the mutant phenotype. The search identified one short period (22 h) mutant (M2) and two low amplitude mutants, one of which showed apparent arhythmia (M11) and one that was still clearly rhythmic (M16). We characterized the disrupted locus of the low amplitude but still rhythmic mutant (M16) as the rpoD2 gene, a member of a gene family that encodes sigma70-like transcription factors in Synechococcus. We also inactivated rpoD2 in a number of reporter strains and showed that the circadian expression of some genes is not modified by the loss of this sigma factor. Therefore, we conclude that rpoD2 is a component of an output pathway of the biological clock that affects the circadian expression of a subset of genes in Synechococcus. This work demonstrates a direct link between a transcription factor and the manifestation of circadian gene expression.

Amino Acid Sequence↗
PubMed1996

An efficient short-step total synthesis of ganglioside GM3: effective usage of the neighbouring group participation strategy.

We have developed an efficient methodology for highly stereoselective sialylation using 3-position substituted sialic acids and have prepared 2a having a 3 beta-phenylthio group as a sialic donor. Glycosylation of suitably protected lactoside 3 with 2a gave only the alpha-sialyl trisaccharide 16 in good yield. Condensation of the azidosphingosine 4 with the acetate 17 using promotors, DMTST or NIS-TfOH, afforded the glycolipid 18, which was directly transformed to 20 by reduction with Bu3P and subsequent acylation with octadecanoic acid in the presence of WSC. Removal of the protecting groups generated ganglioside GM3 (1).

Carbohydrate Sequence↗
PubMed1996

Astroglial cells inhibit the increasing permeability of brain endothelial cell monolayer following hypoxia/reoxygenation.

Blood-brain barrier (BBB) is known to be structured with astroglial cells (AGs) and brain endothelial cells (BECs), and it has been proposed that these cells play different roles in the BBB. We cultivated AGs and BECs from infant rats (2-week-old), and these cells were cultured on the opposing side of collagen membrane to produce a co-culture model of the BBB in vitro. Permeability of the cell layer was evaluated by the electrical resistance through the membrane. To clarify the role of AGs in the BBB disruption following ischemia/reperfusion, electrical resistance of the co-culture model was compared to that of BEC monolayer following hypoxia/reoxygenation. The electrical resistance through BEC monolayer showed 55.5 +/- 15.1 percent reduction at 4 h of hypoxia, and 93.3 +/- 5.4 percent reduction at 8 h of hypoxia (n = 8). However, the co-culture model showed attenuation of the reduction (24.8 +/- 14.2 percent) at 4 h of hypoxia (n = 8, P < 0.01), but not at 8 h of hypoxia (95.3 +/- 5.0 percent). These results indicate that AGs reduce the increasing permeability of the BEC monolayer following short duration of hypoxia/reoxygenation. It is suggested that AGs may have a protective effect to the BBB disruption following ischemia/reperfusion.

Animals↗
PubMed1996

Identification and characterization of presenilin I-467, I-463 and I-374.

We cloned a novel isoform of presenilin I (presenilin I-374) besides previously published presenilin I-467 and I-463 in human lymphocytes. Presenilin I-463 was identical to presenilin I-467 except a 12 bp nucleotides deletion in its amino terminal region. Another isoform, presenilin I-374 was produced by an alternative splicing with an additional exon consisting of 92 bp nucleotides (exon 11), which resulted in the frame shift with a stop codon to generate a truncated presenilin consisting of 374 amino acids. The transcripts for presenilin I-467/463 was ubiquitously detected while that for presenilin I-374 was selectively detected in liver, spleen, kidney. Abnormal behavior of presenilin I on gel electrophoresis was found with affinity-purified antibodies against presenilin I.

Alzheimer Disease↗
PubMed1996

Body surface distribution of significant changes in QRST time-integral values after radiofrequency catheter ablation in patients with Wolff-Parkinson-White syndrome.

We analyzed 87-lead body surface QRST time-integral values (QRST values) in 29 patients with Wolff-Parkinson-White syndrome (group A, 17 patients with manifest left-sided accessory pathway; group B, 6 patients with manifest right-sided accessory pathway; and group C, 6 patients with concealed left-sided accessory pathway), before, 1 day after, and 1 week after radiofrequency catheter ablation (RCA). The number of leads with abnormal QRST values was significantly lower 1 week after RCA compared with those before RCA and 1 day after RCA in groups A and B (p < 0.05); there was no significant difference in QRST values before and 1 day after RCA in groups A and B. The QRST values over areas with preexisting repolarization abnormalities were significantly altered 1 week after RCA compared with before and 1 day after RCA in groups A and B (p < 0.01). However, there was no significant difference in the QRST values over areas without preexisting abnormalities before RCA. In group C, there were no significant differences in the QRST values or the number of leads with abnormal QRST values before, 1 day and 1 week after RCA. In conclusion, RCA did not significantly influence repolarization properties over areas without preexisting abnormalities, but gradually reduced preexisting repolarization abnormalities, which were closely related to the location of the accessory pathway in patients with manifest Wolff-Parkinson-White syndrome. Our results suggest that body surface QRST values are useful for assessment of repolarization abnormalities during the periablation period.

Adolescent↗
PubMed1996

Seroepidemiological study of human herpesvirus-6 and -7 in children of different ages and detection of these two viruses in throat swabs by polymerase chain reaction.

The presence of human herpesvirus 6 (HHV-6) and human herpesvirus 7 (HHV-7) in throat swabs of 62 children of different age groups (group I, ages 0-5 month; group II, ages 6-11 months, group III, ages 12-23 months, group IV, age 2-8 years) and 28 adults was detected by polymerase chain reaction. The detection rate of HHV-6 DNA was the highest (87%) in children aged 1-year-old and decreased with age, whereas the detection rate of HHV-7 increased with age and reached a maximum in adults. HHV-6B was detected in almost all samples except for two children who secreted only HHV-6A. When the antibody prevalence was determined in the four groups of children, HHV-6 antibody was detected in 8/12 (66.7%), 10/12 (83.3%), 15/16 (93.8%), and 13/14 (92.9%), respectively. Antibody to HHV-7 in these groups was detected in 6/12 (50.0%), 4/12 (33.3%), 12/16 (75.0%), and 13/14 (92.9%), respectively. Detection of HHV-6 DNA in throat swabs of triplets who had the sequential onset of exanthem subitum was attempted by using samples sequentially collected from these children after the onset of the disease in the first patient. HHV-6 DNA with high copy numbers was detectable during the acute and convalescent phases of the disease in all patients, but no DNA was detected in samples collected before the onset of disease.

Adult↗
PubMed1996

Characterization of conjugated metabolites of a new angiotensin II receptor antagonist, candesartan cilexetil, in rats by liquid chromatography/electrospray tandem mass spectrometry following chemical derivatization.

Combined liquid chromatography and electrospray mass spectrometry (LC/ESI-MS) and tandem mass spectrometry (MS/MS) were used for the characterization of the conjugated metabolites (glucuronides) of a new angiotensin II receptor antagonist, candesartan cilexetil (TCV-116; (+/-)-1-(cyclohexyloxycarbonyloxy)ethyl 2-ethoxy-1-¿[2'-(1H-tetrazol-5-yl)biphenyl- 4-yl]methyl¿-1H-benzimidazole-7-carboxylate) in the plasma and bile of rats given the drug. The glucuronides of the active component, M-I (candesartan), in rat plasma and bile were positional isomers with respect to the binding site of glucuronic acid. The site of glucuronidation in M-I was not directly identified by mass spectrometry. However, the structure of the isomers could be elucidated by the MS/MS analysis of dimethylated glucuronides prepared by the reaction of glucuronide isomers with diazomethane: N-glucuronide of M-I (M-I-NG) in the plasma and acyl glucuronide (M-I-AG) in the bile. The results obtained in this study indicated that LC/ESI-MS/MS analysis provides the detailed structure of conjugated metabolite by simple chemical derivatization.

Angiotensin II↗