TEL/AML1 overcomes drug resistance through transcriptional repression of multidrug resistance-1 gene expression

The t(12;21)(p12;q22) chromosomal aberration, which is frequently observed in pediatric precursor B-cell acute lymphoblastic leukemia (ALL), generates the TEL/AML1 chimeric gene and protein. TEL/AML1-positive ALL has a favorable prognosis, and one possible reason is that this subtype of ALL rarely shows drug resistance. AML1/ETO, another AML1-containing chimeric protein, has been shown to transcriptionally repress the activity of the multidrug resistance-1 (MDR-1) gene promoter; thus, we examined whether TEL/AML1 also represses MDR-1 gene expression, possibly preventing the emergence of multidrug resistance. In this study, we show that the TEL/AML1 protein binds to the consensus AML1 binding site in the MDR-1 promoter and transcriptionally represses its activity. Following transient transfection of TEL/AML1 protein into Adriamycin-resistant K562/Adr cells, we also demonstrate that TEL/AML1 can down-regulate the expression of P-glycoprotein, a product of the MDR-1 gene, and restore the chemosensitivity to the cells. Furthermore, we report that MDR-1 mRNA levels in leukemic cells obtained from TEL/AML1-positive ALL patients are lower than those from TEL/AML1-negative ALL patients. Thus, TEL/AML1 protein acts as a transcriptional repressor of MDR-1 gene expression, and although TEL/AML1 has been implicated in leukemogenesis, its effects on the MDR-1 gene may contribute to the excellent prognosis of TEL/AML1-positive ALL with current therapy.

TEL/AML1 Overcomes Drug Resistance Through Transcriptional Repression of Multidrug Resistance-1 Gene Expression

The t(12;21)(p12;q22) chromosomal aberration, which is frequently observed in pediatric precursor B-cell acute lymphoblastic leukemia (ALL), generates the TEL/AML1 chimeric gene and protein. TEL/AML1-positive ALL has a favorable prognosis, and one possible reason is that this subtype of ALL rarely shows drug resistance. AML1/ETO, another AML1-containing chimeric protein, has been shown to transcriptionally repress the activity of the multidrug resistance-1 (MDR-1) gene promoter; thus, we examined whether TEL/AML1 also represses MDR-1 gene expression, possibly preventing the emergence of multidrug resistance. In this study, we show that the TEL/AML1 protein binds to the consensus AML1 binding site in the MDR-1 promoter and transcriptionally represses its activity. Following transient transfection of TEL/AML1 protein into Adriamycin-resistant K562/Adr cells, we also demonstrate that TEL/AML1 can down-regulate the expression of P-glycoprotein, a product of the MDR-1 gene, and restore the chemosensitivity to the cells. Furthermore, we report that MDR-1 mRNA levels in leukemic cells obtained from TEL/AML1-positive ALL patients are lower than those from TEL/AML1-negative ALL patients. Thus, TEL/AML1 protein acts as a transcriptional repressor of MDR-1 gene expression, and although TEL/AML1 has been implicated in leukemogenesis, its effects on the MDR-1 gene may contribute to the excellent prognosis of TEL/AML1-positive ALL with current therapy.

Theoretical Debye-Waller factors of alpha-MoO(3) estimated by an equation-of-motion method

EXAFS oscillations of MoO(3), which has a highly asymmetric local structure, have been calculated using backscattering amplitudes and phase shifts derived from the FEFF8 code and using Debye-Waller factors from an equation-of-motion method. They were compared with polarization-dependent empirical EXAFS data of the alpha-MoO(3) single crystal at various temperatures. The theoretical EXAFS oscillations of Mo-O bonds for the [001] direction of the single crystal, where two symmetric Mo-O bonds exist, reproduced well the experimental data. On the other hand, the calculated data for the [100] direction, which contain two asymmetric Mo-O bonds with different bond lengths, agree well with the experimental data only after adjustment of the amplitude reduction factors for different Mo-O bonds. EXAFS oscillations of MoO(3) powder were also calculated by the same method, and theoretical parameters that could reproduce the experimental data were found. These results suggest that the equation-of-motion method can evaluate the Debye-Waller factors efficiently in molecules with asymmetric local structures and can reduce curve-fitting parameters.

Usefulness of residual percent plaque area after percutaneous coronary intervention in predicting peristent positive remodeling

The aim of this study was to determine whether a stented coronary artery might be positively remodeled, which factors predict this phenomenon, and whether positive remodeling has an association with late outcome. The study population consisted of 230 lesions in 230 patients who received bare-metal stents. We performed intravascular ultrasound analyses before and after the procedure and at follow-up. An artery was defined as positively remodeled if the ratio of follow-up to postvessel area was > or =1.1. The following indexes were calculated and defined: (1) late loss = postluminal area - follow-up luminal area; (2) percent plaque area = ([vessel area - luminal area]/vessel area x 100), (3) Delta% plaque area = follow-up percent plaque area - postprocedure percent plaque area. Although late loss in the positively remodeled group was significantly smaller than that in the nonremodeled group (p<0.05), d% plaque area in the former group was significantly larger than that in the latter group (p<0.05). The rate of restenosis in the positive remodeling group (16.4%) was significantly lower than that in the nonremodeling group (28.2%) (p<0.05). In multivariate analysis, postprocedure percent plaque area was the only powerful independent predictor for peristent positive remodeling and was inversely associated with this phenomenon in both groups (odds ratio 0.944, 95% confidence interval 0.914 to 0.975, p=0.0004). This study indicates that postprocedure percent plaque area could predict the occurrence of peristent positive remodeling at follow-up and that this phenomenon might influence late outcome.

Evaluation of restenosis in major vessels and side branches

OBJECTIVES

The indications for concurrent intervention for stenosis of a side branch during the treatment for stenosis of the main vessel were investigated using quantitative coronary angiography.

METHODS

The retrospective study included 451 patients treated for a stenotic main vessel incorporating a side branch, who underwent follow-up angiography within 6 months. Patients were divided into Group I with the side branch treated by coronary angioplasty, and Group II with the side branch left untreated. Quantitative coronary angiography was used to measure the minimum luminal diameter (MLD) and percentage diameter stenosis (%DS) of the main vessel and the side branch.

RESULTS

The MLD of the side branch after treatment was larger in Group I (1.4 +/- 0.1 mm) than in Group II (0.7 +/- 0.1 mm), and the %DS of the side branch after treatment was smaller in Group I (34 +/- 3%) than in Group II (63 +/- 2%). These differences decreased at follow-up to 1.1 +/- 0.1 mm, 48 +/- 2% in Group I; 0.9 +/- 0.04 mm, 46 +/- 2% in Group II, respectively. The MLD and %DS of the side branch at follow-up in Groups I and II were affected by the presence of main vessel restenosis[Restenosis(+): 0.9 +/- 0.1 mm, 57 +/- 4%; restenosis(-): 1.2 +/- 0.1 mm (p < 0.05), 43 +/- 3% (p < 0.05) in Group I; Restenosis(+): 0.9 +/- 0.1 mm, 51 +/- 8%; restenosis(-): 1.0 +/- 0.1 mm, 44 +/- 3% in Group II]. Multivariate analysis showed that %DS of the main vessel at follow-up was the only powerful predictor of restenosis of the side branch (p = 0.0249, odds ratio = 1.031, confidence interval = 1.004-1.059) in Groups I and II.

CONCLUSIONS

Restenosis of the main vessel rather than the initial outcome of the side branch is the major influence on restenosis of the side branch.

Gas6 rescues cortical neurons from amyloid beta protein-induced apoptosis

Gas6, a product of the growth-arrest-specific gene 6, protects neurons from serum deprivation-induced apoptosis. Neuronal apoptosis is also caused by amyloid beta protein (Abeta), whose accumulation in the brain is a characteristic feature of Alzheimer's disease. Abeta induces Ca(2+) influx via L-type voltage-dependent calcium channels (L-VSCCs), leading to its neurotoxicity. In the present study, we investigated effects of Gas6 on Abeta-induced cell death in primary cultures of rat cortical neurons. Abeta caused neuronal cell death in a concentration- and time-dependent manner. Gas6 significantly prevented neurons from Abeta-induced cell death. Gas6 ameliorated Abeta-induced apoptotic features such as the condensation of chromatin and the fragmentation of DNA. Prior to cell death, Abeta increased influx of Ca(2+) into neurons through L-VSCCs. Gas6 significantly inhibited the Abeta-induced Ca(2+) influx. The inhibitor of L-VSCCs also suppressed Abeta-induced neuronal cell death. The present cortical cultures contained few non-neuronal cells, indicating that Gas6 affected the survival of neurons directly, but not indirectly via non-neuronal cells. In conclusion, we demonstrate that Gas6 rescues cortical neurons from Abeta-induced apoptosis. Furthermore, the present study indicates that inhibition of L-VSCC contributes to the neuroprotective effect of Gas6.

Extraction of previously deployed stent by an entrapped cutting balloon due to the blade fracture

During treatment for in-stent restenosis, entrapment of cutting balloon occurred because of the blade fracture. Removal of the balloon caused stent extraction, inducing acute occlusion of the coronary artery. Application of cutting balloon for in-stent restenosis requires every caution against such type of complications.

Chiral autocatalysis, spontaneous symmetry breaking, and stochastic behavior

During the past decade, chirally autocatalytic systems that exhibit unusual and interesting phenomena, such as spontaneous chiral symmetry breaking and stochastic behavior, have been identified. In this Account we outline the context in which chiral autocatalysis is of interest, summarize recent advances, and discuss our current understanding of the underlying kinetics and mechanisms. In addition, we note some fundamental aspects of amplification of enantiomeric excess and sensitivity of symmetry breaking transitions to asymmetric factors.

Deterioration of axotomy-induced neurodegeneration by group IIA secretory phospholipase A2

Phospholipase A2 (PLA2) is proposed to play a role in the repair of the ruptured membrane after axotomy. In neonatal rats, we examined the effect of Group IIA secretory PLA2 (sPLA2-IIA) on axotomy-induced cell death of motoneurons. sPLA2-IIA significantly induced death of axotomized motoneurons. Indoxam, a specific inhibitor for sPLA2-IIA, protected motoneurons from the sPLA2-IIA-induced deterioration. The present study indicated that sPLA2-IIA possessed neurotoxic effect rather than neuroprotective effect against facial nerve.

Association of L* protein of Theiler's murine encephalomyelitis virus with microtubules in infected cells

We used an antibody raised against a synthetic peptide corresponding to amino acid residues 70-88 for characterizing the L* protein of Theiler's murine encephalomyelitis virus (TMEV), which is only synthesized in DA subgroup strains from an alternative AUG and is out of frame with the viral polyprotein; evidence suggests that L* protein is critical to viral persistence, demyelination, and growth in murine macrophage cell lines. It was synthesized with kinetics similar to that of other viral proteins, although less in amount. After synthesis, it remained stable in the cytoplasm and was not incorporated into virions. Immunofluorescent staining and immunoblotting of microtubule preparations demonstrated that it is associated with microtubules. Expression of L* protein also demonstrated that the 5' one third of the coding region may be responsible for the association. The association of L* protein with microtubules may be important in the disease-inducing and in vitro characters of L* protein.

Effects of S-2474, a novel nonsteroidal anti-inflammatory drug, on amyloid beta protein-induced neuronal cell death

1. The accumulation of amyloid beta protein (Abeta) in the brain is a characteristic feature of Alzheimer's disease (AD). Clinical trials of AD patients with nonsteroidal anti-inflammatory drugs (NSAIDs) indicate a clinical benefit. NSAIDs are presumed to act by suppressing inhibiting chronic inflammation in the brain of AD patients. 2. In the present study, we investigated effects of S-2474 on Abeta-induced cell death in primary cultures of rat cortical neurons. 3. S-2474 is a novel NSAID, which inhibits cyclo-oxygenase-2 (COX-2) and contains the di-tert-butylphenol antioxidant moiety. S-2474 significantly prevented neurons from Abeta(25 - 35)- and Abeta(1 - 40)-induced cell death. S-2474 ameliorated Abeta-induced apoptotic features such as the condensation of chromatin and the fragmentation of DNA completely. 4. Prior to cell death, Abeta(25 - 35) generated prostaglandin D(2) (PGD(2)) and free radicals from neurons. PGD(2) is a product of cyclo-oxygenase (COX), and caused neuronal cell death. 5. S-2474 significantly inhibited the Abeta(25 - 35)-induced generation of PGD(2) and free radicals. 6. The present cortical cultures contained little non-neuronal cells, indicating that S-2474 affected neuronal survival directly, but not indirectly via non-neuronal cells. Both an inhibitory effect of COX-2 and an antioxidant effect might contribute to the neuroprotective effects of S-2474. 7. In conclusion, S-2474 exhibits protective effects against neurotoxicity of Abeta. Furthermore, the present study suggests that S-2474 may possess therapeutic potential for AD via ameliorating degeneration in neurons as well as suppressing chronic inflammation in non-neuronal cells.

Conditions for chiral asymmetry generation in the preparation of the chiral octahedral cobalt complex

We have reported that the random chiral asymmetry generation, which is a spontaneous preferential generation of one enantiomer, was observed in the synthesis of a chiral octahedral cobalt complex, cis-[CoBr(NH(3))(en)(2)]Br(2). In this article, we review our studies to explain in this system the autocatalytic growth of small enantiomeric excess that arises due to statistical fluctuations. One important experimental finding was that the rate of chiral autocatalysis increased with increasing the degree of supersaturation. Furthermore, our numerical simulation indicates that even small inhomogeneities in the reaction system may play a significant role because their effect is amplified by the autocatalytic reaction under appropriate conditions. In a small volume, fluctuations in concentration can grow if the autocatalytic growth overcomes the diffusional loss of the excess concentration from this volume. This may makes the enantiomeric excess of the chiral complex randomly fluctuate from run to run.

Synthesis and structure–activity relationships of potent and orally active sulfonamide ETB selective antagonists

The synthesis and structure activity relationships of a series of N-pyrimidinyl benzenesulfonamides as ETB selective antagonists are described. N-Isoxazolyl benzenesulfonamide 1a, previously reported, (1) was selected as a lead compound, and isosteric replacement of the isoxazole ring of 1a with a pyrimidine ring led to the discovery of the highly potent ETB selective antagonist 6e with oral bioavailability. Modification of the terminal aldehyde group at the 6-position of the pyrimidine ring was investigated, and malonate 15b and acylhydrazone 16f were found to be equipotent to aldehyde 6e. Compound 6e showed ETB antagonistic activity on in vivo evaluation.

DXAFS study on the decarbonylation process of Mo(CO)6 in NaY supercages

The decarbonylation process of Mo(CO)6 in the NaY supercages was studied by means of a time resolved dispersive XAFS method during temperature programmed decarbonylation. XANES analysis demonstrated that the decarbonylation proceeded through two steps and that a stable intermediate existed between 440-490 K. The curve fitting analysis revealed that the intermediate was a molybdenum monomer subcarbonyl species coordinated by three CO ligands and three oxygen atoms of zeolite framework. Molybdenum dimer subcarbonyl species were not observed. This study demonstrated that DXAFS technique is a powerful method to study the dynamic behaviour of the Mo carbonyl species during decarbonylation process.