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T Okada

Publications and source records attributed to T Okada.

At least 73 records · Page 4Linked to original sources
PubMed2002

Selective growth advantage of wild-type lymphocytes in X-linked SCID recipients.

The cytokine receptor common gamma chain (gamma c) plays a pivotal role in multiple interleukin signaling, and gamma c gene mutations cause an X-linked form of SCID (X-SCID). Recently, gamma c gene transfer into the autologous X-SCID BM achieved appreciable lymphocyte reconstitution, contrasting with the limited success in previous gene therapy trials targeting hematopoietic stem cells. To understand the mechanisms underlying this success, we examined the repopulating potential of the wild-type (WT) BM cells using an X-SCID mouse model. Limited numbers of WT cells were infused into non-ablated WT and X-SCID hosts. Whereas no appreciable engraftment was observed in WT recipients, donor-derived lymphocytes repopulated well in X-SCID, reaching 37% (10(6)cells given) and 53% (10(7) cells given) of the normal control value 5 months post BMT. A lineage analysis showed a predominance of the donor-derived lymphocytes (CD4(+) T, CD8(+) T, B and NK cells) in X-SCID while the donor-derived granulocytes and monocytes engrafted poorly. These results showed a selective advantage of WT cells in X-SCID, and that the advantage was restricted to lymphocytes. In human gene therapy for X-SCID, an analogous growth advantage would greatly enhance the repopulation of lymphocytes derived from a very small number of gamma c gene-supplemented precursors.

Animals↗
PubMed2002

Delayed delivery of AAV-GDNF prevents nigral neurodegeneration and promotes functional recovery in a rat model of Parkinson's disease.

Glial cell line-derived neurotrophic factor (GDNF) is a strong candidate agent in the neuroprotective treatment of Parkinson's disease (PD). We investigated whether adeno-associated viral (AAV) vector-mediated delivery of a GDNF gene in a delayed manner could prevent progressive degeneration of dopaminergic (DA) neurons, while preserving a functional nigrostriatal pathway. Four weeks after a unilateral intrastriatal injection of 6-hydroxydopamine (6-OHDA), rats received injection of AAV vectors expressing GDNF tagged with FLAG peptide (AAV-GDNFflag) or beta-galactosidase (AAV-LacZ) into the lesioned striatum. Immunostaining for FLAG demonstrated retrograde transport of GDNFflag to the substantia nigra (SN). The density of tyrosine hydroxylase (TH)-positive DA fibers in the striatum and the number of TH-positive or cholera toxin subunit B (CTB, neuronal tracer)-labeled neurons in the SN were significantly greater in the AAV-GDNFflag group than in the AAV-LacZ group. Dopamine levels and those of its metabolites in the striatum were remarkably higher in the AAV-GDNFflag group compared with the control group. Consistent with anatomical and biochemical changes, significant behavioral recovery was observed from 4-20 weeks following AAV-GDNFflag injection. These data indicate that a delayed delivery of GDNF gene using AAV vector is efficacious even 4 weeks after the onset of progressive degeneration in a rat model of PD.

Animals↗
PubMed2002

Improvement of growth and nutritive value in chicks with non-genetically modified phytase product from Aspergillus niger.

1. Non-genetically modified (non-GM) phytase product derived from Aspergillus niger possesses various side active enzymes including alpha-amylase, protease, cellulase and hemicellulase. In contrast, the product of genetically modified (GM) phytase product has much less side active enzyme since the capacity of phytase production is reinforced by gene modification. In the present study we have tried to determine whether the difference of side enzyme activity of phytase product affects growth performances and nutritive value in chicks; in addition we tried to characterise the physiological change induced by the difference of side active enzymes. 2. Single Comb White Leghorn male chicks at 7 d of age were fed on experimental barley-based diets for 10 d. The feeding trial was of a factorial design (3 x 2 x 2), having three types of dietary phytase products (control, non-GM or GM phytase products derived from A. niger at 1000 U/kg diet), two levels of dietary available P supplement (0 or 6 g/kg diet) and two levels of dietary protein (CP 180 or 120 g/kg). 3. The non-GM phytase product caused a 6% increase in final body weight and feed efficiency compared with the control and the GM phytase product without interacting with dietary protein and available P level. However, in birds given available P-free diet, both non-GM and GM phytase products induced a 20% increase in plasma P concentration, suggesting no difference in phytase activity between the non-GM and GM phytase products. 4. The balance study showed that the metabolisable energy of the non-GM phytase product (15.6 +/- 0.05 kJ/g diet) was significantly higher among the treatments (control, 15.1 +/- 0.05; GM phytase product 15.3 +/- 0.07). The non-GM phytase product also increased the rate of food passage through the crop, and caused a drastic reduction in intestinal weight, perhaps as a consequence of digestion of non-starch polysaccharides. 5. We conclude that the side active enzymes in non-GM phytase product improve growth performance and nutritive value of the diet in chicks. However, the efficacy of phytase activity should not be different between non-GM and GM phytase products.

6-Phytase↗
PubMed2002

Abnormal cortical mechanisms of voluntary muscle relaxation in patients with writer's cramp: an fMRI study.

Although it is hypothesized that there is abnormal motor inhibition in patients with dystonia, the question remains as to whether the mechanism related to motor inhibition is specifically impaired. The objective of the present study was to clarify the possible abnormalities of the mechanisms underlying voluntary muscle relaxation during motor preparation and execution in patients with writer's cramp, using event-related functional MRI. Eight patients with writer's cramp and 12 age-matched control subjects participated in the study. Two motor tasks were employed as an experimental paradigm. In the relaxation task, subjects were asked to hold their right wrist in the horizontal plane by maintaining moderate contraction of wrist extensor muscles in the premotor phase; they relaxed those muscles voluntarily just once during each fMRI scanning session. In the contraction task, subjects extended the right wrist voluntarily from the same premotor state as for the relaxation task. Five axial images covering the primary sensorimotor cortex (SMC) and supplementary motor area (SMA) were obtained once every second. Activated volumes in the left SMC and the SMA were significantly reduced in patients for both muscle relaxation and contraction tasks. These data suggest that there is impaired activation in both SMC and SMA in voluntary muscle relaxation and contraction in patients with writer's cramp. This implies that abnormalities of both inhibitory and excitatory mechanisms in motor cortices might play a role in the pathophysiology of focal dystonia.

Adult↗
PubMed2002

Non-invasive measurement of coronary flow reserve in children with Kawasaki disease.

OBJECTIVE: To investigate whether transthoracic Doppler echocardiography (TTE) can reliably measure the coronary flow reserve in the left anterior descending coronary artery in children with Kawasaki disease. DESIGN: Coronary flow velocity in the distal left anterior descending coronary artery was measured by TTE and was compared with that obtained by intracoronary Doppler guide wire. The ratio of maximum hyperaemia (intravenous administration of adenosine triphosphate, 160 microg/kg/min) to baseline peak (mean) diastolic coronary flow velocity in the distal artery was used as an estimate of coronary flow reserve. SETTING: University hospital. PATIENTS: 10 patients with significant left anterior descending coronary stenosis (> 70% diameter stenosis) (group A) in the proximal or middle portion of the artery and 14 patients (group B) without significant stenosis, all with Kawasaki disease documented by previous coronary angiography. RESULTS: The reduced hyperaemic coronary flow velocity in group A compared with group B resulted in a markedly lower coronary flow reserve, derived from both peak diastolic velocity and mean diastolic velocity by either technique of investigation. Multivariate analysis identified the best predictor of left anterior descending coronary artery stenosis to be a coronary flow reserve of < or = 2.2, derived from mean diastolic flow velocity measured using TTE (sensitivity 90%, specificity 100%, accuracy 96%). A good correlation was found between diastolic velocity derived values for coronary flow reserve measured using both TTE and Doppler guide wire (r = 0.92, p = 0.0001). CONCLUSIONS: Coronary flow reserve in the distal left anterior descending coronary artery can be accurately measured using TTE without any intravascular instrumentation in children with Kawasaki disease.

Adolescent↗
PubMed2002

Long-term results of chronic hemodialysis patients with isolated coronary artery bypass grafting performed by the same surgeon. A comparative study.

BACKGROUND: The aim of this study was to examine the long-term results of isolated coronary artery bypass grafting (CABG) patients who required chronic hemodialysis. METHODS: From May 1990 to June 2000, 23 hemodialysis patients received isolated CABG performed by the same surgeon. Postoperative follow-up was completed with maximum duration of 122 months. RESULTS: Operative deaths (n=2) were due to acute circulatory failure related to hemodialysis. The most frequent cause of late deaths (n=10) was infection. Five (50%) patients died of sepsis, and 80% of sepsis was caused by leg infection associated with arteriosclerosis obliterans. There were 6 late cardiac events including 3 cardiac deaths. The actual survival rates 1, 3, 5 and 7 years after CABG were 68.6%, 42.5%, 35.4% and 35.4%, respectively. And the actual cardiac event free rates 1, 3, 5 and 7 years after CABG were 77.6%, 77.6%, 46.6% and 46.6%, respectively. Operative mortality (p=0.019), long-term survival (p<0.001) and cardiac event free rate (p=0.002) were significantly poorer in hemodialysis patients than in non-hemodialysis patients. However, the long-term survival rate of our hemodialysis patients receiving isolated CABG was almost similar to that in dialysis patients without CABG. The etiology of chronic renal failure did not significantly affect long-term RESULTS. Using internal thoracic artery graft significantly (p=0.02) decreased the late cardiac event in hemodialysis patients, although it did not improve late survival. CONCLUSIONS: Primary CABG followed by aggressive re-intervention have the benefit of preventing late cardiac death in hemodialysis patients. However, prevention of sepsis and treatment of arteriosclerosis obliterans are important for improving the late survival in hemodialysis patients receiving isolated CABG.

Aged↗
PubMed2001

XBP1 mRNA is induced by ATF6 and spliced by IRE1 in response to ER stress to produce a highly active transcription factor.

In yeast, the transmembrane protein kinase/endoribonuclease Ire1p activated by endoplasmic reticulum stress cleaves HAC1 mRNA, leading to production of the transcription factor Hac1p that activates the unfolded protein response (UPR). In mammals, no Hac1p counterpart has yet been discovered despite the presence of Ire1p homologs in the endoplasmic reticulum. Instead, the transcription factor ATF6 specific to the mammalian UPR is regulated by intramembrane proteolysis. Here, we identified the transcription factor XBP1, a target of ATF6, as a mammalian substrate of such an unconventional mRNA splicing system and showed that only the spliced form of XBP1 can activate the UPR efficiently. Our results reveal features of the UPR conserved during evolution and clarify the relationship between IRE1- and ATF6-dependent pathways.

Activating Transcription Factor 6↗
PubMed2001

Mononuclear platinum(II) complex with 2-phenylpyridine ligands showing high cytotoxicity against mouse sarcoma 180 cells acquiring high cisplatin resistance.

Mouse sarcoma 180 cell with a 25-fold higher cisplatin (CDDP) resistance, termed S-180cisR, is newly established. S-180cisR cells grow quite slowly in the presence of CDDP with high concentration. This may show that S-180cisR cells modulate the cell cycle to acquire CDDP resistance. P-Glycoprotein is selectively expressed on the surface of S-180cisR, which is not on CDDP-sensitive S-180 parent cells. In an experiment using an inhibitor (verapamil) of P-glycoprotein, cytotoxicity of CDDP against S-180cisR is significantly increased (viz., IC(50) value is decreased) and accumulation of CDDP in S-180cisR cells is also increased. These results indicate that enhanced pumping-out of CDDP by P-glycoprotein should be one of the reasons for the CDDP resistance of S-180cisR. A platinum(II) complex with a cyclometalated 2-phenylpyridine ligand and a nonchelated one (complex 5) is synthesized, and its structure is determined by X-ray structural analysis. Complex 5 has a cyctotoxicity against S-180cisR higher than that of CDDP and its derivatives with 2- or 3-substituted pyridine ligands (complexes 2-4, 6, 7). Complex 5 is incorporated in S-180cisR to an enormously greater extent than CDDP; that is, the ratio of accumulated platinum amount after 3 h is 61.9. In S-180 parent cells, on the other hand, the ratio remains 8.1. This high accumulation of complex 5 into S-180cisR must account for the higher activity of complex 5 against S-180cisR compared to CDDP.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2001

BDCA-2, a novel plasmacytoid dendritic cell-specific type II C-type lectin, mediates antigen capture and is a potent inhibitor of interferon alpha/beta induction.

Plasmacytoid dendritic cells are present in lymphoid and nonlymphoid tissue and contribute substantially to both innate and adaptive immunity. Recently, we have described several monoclonal antibodies that recognize a plasmacytoid dendritic cell-specific antigen, which we have termed BDCA-2. Molecular cloning of BDCA-2 revealed that BDCA-2 is a novel type II C-type lectin, which shows 50.7% sequence identity at the amino acid level to its putative murine ortholog, the murine dendritic cell-associated C-type lectin 2. Anti-BDCA-2 monoclonal antibodies are rapidly internalized and efficiently presented to T cells, indicating that BDCA-2 could play a role in ligand internalization and presentation. Furthermore, ligation of BDCA-2 potently suppresses induction of interferon alpha/beta production in plasmacytoid dendritic cells, presumably by a mechanism dependent on calcium mobilization and protein-tyrosine phosphorylation by src-family protein-tyrosine kinases. Inasmuch as production of interferon alpha/beta by plasmacytoid dendritic cells is considered to be a major pathophysiological factor in systemic lupus erythematosus, triggering of BDCA-2 should be evaluated as therapeutic strategy for blocking production of interferon alpha/beta in systemic lupus erythematosus patients.

Amino Acid Sequence↗
PubMed2001

Sgn1, a basic helix-loop-helix transcription factor delineates the salivary gland duct cell lineage in mice.

The salivary system in mammals is comprised of three independently developed pairs of organs, the parotid, submaxillar, and sublingual glands. Each gland is composed of various ductal and acinar cell types that fulfill multiple roles. However, the molecular mechanisms regulating their biogenesis and functions are still largely unknown. In this paper, we report that two class B basic helix-loop-helix (bHLH) transcriptional regulators delineate the ductal and the acinar cells in salivary glands. Sgn1, a novel class B bHLH factor, is specifically expressed in the salivary duct cells, while the acinar cells are characterized by the expression of another class B bHLH factor, Mist1. The molecular nature of Sgn1 was also investigated: it binds to specific sequences of DNA as a dimer with a class A bHLH factor and acts as a negative transcriptional regulator against other bHLH factors. This study provides an important cue towards better understanding of the generation and function of multiple cell types in salivary glands. In addition, Sgn1 expression exhibits a reverse relationship with the development of male phenotypes, suggesting its role in gender dimorphism in the salivary glands.

Amino Acid Sequence↗
PubMed2001

Squalene synthase inhibitors reduce plasma triglyceride through a low-density lipoprotein receptor-independent mechanism.

Inhibitors of squalene synthase are considered to be candidate drugs to reduce both plasma cholesterol and triglyceride. However, little is known about the mechanism of squalene synthase inhibitor-specific effect on plasma triglyceride. In this study, we confirmed the triglyceride-lowering effect of ER-27856, a potent squalene synthase inhibitor prodrug, in rhesus monkeys. To determine the role of low-density lipoprotein (LDL) receptor in the triglyceride-lowering effect of squalene synthase inhibitors, we intravenously administered ER-28448, the active form of ER-27856, to Watanabe heritable hyperlipidemic (WHHL) rabbits for 4 days. In heterozygotes, ER-28448 reduced plasma cholesterol and triglyceride by 52% and 37%, respectively. In homozygous rabbits, in contrast, ER-28448 lowered plasma triglyceride by 40% but did not lower plasma cholesterol. Orally administered ER-27856 reduced plasma triglyceride in homozygous animals but atorvastatin and bezafibrate did not. In hepatocytes isolated from homozygous WHHL rabbits, squalene synthase inhibitors but not atorvastatin reduced triglyceride biosynthesis. These data demonstrate that squalene synthase inhibitors reduced plasma triglyceride through an LDL receptor-independent mechanism, which was distinct from that of the triglyceride-lowering action of atorvastatin or bezafibrate. The reduction of hepatic triglyceride biosynthesis may play an important role in the hypotrigyceridemic action of squalene synthase inhibitors.

Animals↗
PubMed2001

Neural interaction of the amygdala with the prefrontal and temporal cortices in the processing of facial expressions as revealed by fMRI.

Some involvement of the human amygdala in the processing of facial expressions has been investigated in neuroimaging studies, although the neural mechanisms underlying motivated or emotional behavior in response to facial stimuli are not yet fully understood. We investigated, using functional magnetic resonance imaging (fMRI) and healthy volunteers, how the amygdala interacts with other cortical regions while subjects are judging the sex of faces with negative, positive, or neutral emotion. The data were analyzed by a subtractive method, then, to clarify possible interaction among regions within the brain, several kinds of analysis (i.e., a correlation analysis, a psychophysiological interaction analysis and a structural equation modeling) were performed. Overall, significant activation was observed in the bilateral fusiform gyrus, medial temporal lobe, prefrontal cortex, and the right parietal lobe during the task. The results of subtraction between the conditions showed that the left amygdala, right orbitofrontal cortex, and temporal cortices were predominantly involved in the processing of the negative expressions. The right angular gyrus was involved in the processing of the positive expressions when the negative condition was subtracted from the positive condition. The correlation analysis showed that activity in the left amygdala positively correlated with activity in the left prefrontal cortex under the negative minus neutral subtraction condition. The psychophysiological interaction revealed that the neural responses in the left amygdala and the right prefrontal cortex underwent the condition-specific changes between the negative and positive face conditions. The right amygdaloid activity also had an interactive effect with activity in the right hippocampus and middle temporal gyrus. These results may suggest that the left and right amygdalae play a differential role in effective processing of facial expressions in collaboration with other cortical or subcortical regions, with the left being related with the bilateral prefrontal cortex, and the right with the right temporal lobe.

Adult↗
PubMed2001

Regulation of mammalian phospholipase D2: interaction with and stimulation by G(M2) activator.

We have previously reported that a heat-stable activator for ganglioside metabolism, G(M2) activator, potently stimulates ADP-ribosylation factor (ARF)-dependent phospholipase D (PLD) activity (presumably PLD1) in an in vitro system [Nakamura, Akisue, Jinnai, Hitomi, Sarkar, Miwa, Okada, Yoshida, Kuroda, Kikkawa and Nishizuka (1998) Proc. Natl. Acad. Sci. U.S.A. 95, 12249-12253]. However, little is known about the regulation of PLD2. In the present studies we have investigated the regulation of PLD2 by G(M2) activator and various other regulators including ARF. PLD2 was potently stimulated in vitro by G(M2) activator in a time- and dose-dependent manner. Neither ARF nor protein kinase C caused any significant changes in PLD2 activity. Importantly, PLD2 responsiveness to ARF was greatly enhanced by G(M2) activator, suggesting a possible role for G(M2) activator as a coupling factor. G(M2) activator was also demonstrated to physically associate with PLD2 in a stoichiometric manner. Further, PMA stimulation of COS-7 cells overexpressing both G(M2) activator and PLD2 resulted in a marked increase in the association of the two molecules. Interestingly, ARF association with PLD2 was greatly increased by G(M2) activator. Moreover, G(M2) activator enhanced PMA-induced PLD activity in a synergistic manner with ARF in streptolysin-O-permeabilized, cytosol-depleted HL-60 cells, suggesting that G(M2) activator may regulate PLD in a concerted manner with other factors, including ARF, inside the cells.

Amino Acid Sequence↗
PubMed2001

Development and characterization of an antisense-mediated prepackaging cell line for adeno-associated virus vector production.

One of the limitations of recombinant adeno-associated virus (rAAV) vector systems for gene therapy applications has been the difficulty in producing the vector in sufficient quantity for adequate evaluation. Since the AAV Rep proteins are cytotoxic, it is not easy to establish stable cell lines that express them constitutively. We describe a novel 293-derived prepackaging cell line which constitutively expresses the antisense rep/cap driven by a loxP-flanked CMV promoter. This cell line was converted into a packaging cell line expressing Rep/Cap for rAAV vector production through adenovirus-mediated introduction of a Cre recombinase gene. Without the introduction of the Cre recombinase gene, the cell line was shown to produce neither Rep nor Cap. rAAV vector was produced (1 x 10(9) genome copies/3.5-cm dish) 4 days after the transduction with Cre-expression adenovirus vector together with transfection of AAV vector plasmid. We further showed that the addition of Cap-expression adenovirus vector caused a 10-fold increase in the yield of rAAV vector. This system is also capable of producing rAAV as a transfection-free system by using a small amount of rAAV instead of vector plasmid.

Adenoviridae↗
PubMed2001

Reversible integration of the dominant negative retinoid receptor gene for ex vivo expansion of hematopoietic stem/progenitor cells.

Since hematopoietic stem cells (HSCs) differentiate readily ex vivo resulting in the loss of self-renewal and engraftment abilities, the transient block of differentiation is essential to maintain those abilities during their ex vivo expansion culture. To this end, we developed a method of reversible integration of the dominant negative retinoic acid receptor (DN-RAR) gene, a differentiation-blocking gene, into cells utilizing the Cre/loxP-dependent gene recombination system. The murine immature hematopoietic 32D cells differentiate into mature neutrophils upon G-CSF treatment. However, 32D cells transduced with a retroviral vector expressing the DN-RAR gene put between two loxP sites continued to proliferate without showing differentiation even in the presence of G-CSF. After the cells were fully amplified, the cells were transduced with the Cre recombinase gene. The cells then restored the ability to differentiate into mature neutrophils upon G-CSF treatment. PCR analysis showed that the DN-RAR gene was efficiently removed from the genome by introduction of the Cre gene. This system may eventually be applicable to the ex vivo expansion of HSCs.

Animals↗