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Biomedical subjects

Takashi Ohshima

Publications and source records attributed to Takashi Ohshima.

At least 19 recordsLinked to original sources
PubMed2006

Stable top-up operation at SPring-8.

Top-up operation allows SPring-8 to provide highly stable X-ray beams with arbitrary filling patterns. The implementation of top-up operation is described, with a focus on the simultaneous achievement of stability of stored current, beam orbit, purity of an isolated single bunch, and beam injection efficiency. Stored-current fluctuations have been routinely reduced to a level of 10(-3). Stored-beam oscillation on frequent beam injection, which was originally regarded as the most serious problem, has been successfully suppressed to a sufficiently low level that it never perturbs imaging experiments. Current impurities in nominally empty buckets have been reduced to a level of 10(-9) over more than one week of operation, making possible the measurement of time-resolved spectra using high-current bunches. Finally, excellent injection efficiency, higher than 80%, is routinely obtained, even for small undulator gaps, which is critical for preventing radiation damage to insertion-device magnets and to reduce leakage radiation. The process of achieving highly stabilized top-up operation at SPring-8 and its utility for user experiments are described.

Electrons↗
PubMed2006

[Low-dose weekly paclitaxel therapy proved useful for a case of recurrent gastric cancer with clinically latent hepatic cirrhosis].

The patient was a 68-year-old-man who suffered from recurrent peritoneal gastric cancer. He was initially treated with TS-1 as an outpatient. However, his serum CEA level elevated in March 2004, and he complained of epigastric pain in June. A chest and abdominal CT revealed lung and local recurrence. He began weekly paclitaxel as second-line chemotherapy in September. Paclitaxel was infused once a week for two weeks as one cycle, at a dose of 60 mg because of the clinically latent hepatic cirrhosis. One month after the first infusion therapy, epigastric pain was greatly reduced. A CT scan showed the lung metastasis had disappeared and the size of the tumor around the anastomosis was reduced to 50% after 2 months. The toxic events were appetite loss (grade 2) and alopecia (grade 2).

Aged↗
PubMed2006

[Clinical results of single therapy with TS-1 for advanced/recurrent gastric cancer].

In cases with advanced/recurrent gastric cancer undergoing single therapy with TS-1, we retrospectively discussed the antitumor effects and adverse events and considered the clinical utility of TS-1. The subjects consisted of 131 cases with advanced/recurrent gastric cancer who received one or more courses of therapy with TS-1 alone between July 1999 and August 2003. We carried out 4-week administration of 80-120 mg/day of TS-1 according to body surface area, followed by a 2-week discontinuation, then repeated administration which adjusting the dosage according to the incidence of side effects, and discussed the antitumor effects and adverse events. The response rate in all cases was 21% and the median survival time (MST) was 343 days, or 25.3% and 265 days if limited to unresectable and recurrent cases. The response rates were 38.2% for unresectable cases, 16.3% for recurrent cases and 14.6% for curability C cases, and the MSTs were 250 days, 276 days and 419 days, respectively. The response rates in terms of whether or not patients had received chemotherapy were 11.6% for those who had received chemotherapy and 40.0% for those who had not, and the MSTs were 239 days and 325 days, respectively. Thus, both were significantly better in patients who had not received chemotherapy. The response rates for patients who had not received chemical therapy by target organs were favorable on the order of 50% for stomach and 33% for liver metastasis, and the MSTs were on the order of 474 days for peritoneum, 39 1 days for liver metastasis and 326 days for lymph nodes. There were 10 cases of long-term survival of 600 days or longer, but not in unresectable cases, and the target organs in many of the cases were the peritoneum and lymph nodes. Adverse reactions were observed in 34.4% of all cases and those of grade 3 or more in 9.4%, all of which were improved only by discontinuation of the drug. It was again confirmed that single therapy with TS-1 for advanced/recurrent gastric cancer is an excellent therapy providing both high antitumor effects and safety.

Adenocarcinoma↗
PubMed2006

[Clinical efficacy and safety of weekly paclitaxel therapy as second-line chemotherapy for patients with advanced and recurrent gastric cancer who were previously treated with TS-1 therapy].

The clinical efficacy and safety of weekly paclitaxel therapy were studied retrospectively in 17 patients with advanced and recurrent gastric cancer who had previously been treated with TS-1 therapy. The overall response rate was 0%, but MST was 495 days. The adverse effects observed were grade 3 leukopenia in 2 patients (11.8%) and grade 1 and 2 alopecia in 13 patients (76.5%). However, weekly paclitaxel therapy was performed for all outpatients. Weekly paclitaxel therapy could be useful and safe as second-line chemotherapy.

Aged↗
PubMed2005

Asymmetric alkynylation of aldehydes catalyzed by an In(III)/BINOL complex.

Asymmetric alkynylation of both aromatic and aliphatic aldehydes using catalytic amounts of In(III)/BINOL is described. Dual activation of both substrates due to the "bifunctional character" of the indium(III) catalyst enables a broad range of substrate generality with high enantioselectivity (83 to >99% ee).

Aldehydes↗
PubMed2005

Dynamic structural change of the self-assembled lanthanum complex induced by lithium triflate for direct catalytic asymmetric aldol-Tishchenko reaction.

The development of a direct catalytic asymmetric aldol-Tishchenko reaction and the nature of its catalyst are described. An aldol-Tishchenko reaction of various propiophenone derivatives with aromatic aldehydes was promoted by [LaLi3(binol)3] (LLB), and reactivity and enantioselectivity were dramatically enhanced by the addition of lithium trifluoromethanesulfonate (LiOTf). First, we observed a dynamic structural change of LLB by the addition of LiOTf using 13C NMR spectroscopy, electronspray ionization mass spectrometry (ESI-MS), and cold-spray ionization mass spectrometry (CSI-MS). X-ray crystallography revealed that the structure of the newly generated self-assembled complex was a binuclear [La2Li4(binaphthoxide)5] complex 6. A reverse structural change of complex 6 to LLB by the addition of one equivalent of Li2(binol) was also confirmed by ESI-MS and experimental results. The drastic concentration effects on the direct catalytic asymmetric aldol-Tishchenko reaction suggested that the addition of LiOTf to LLB generated an active oligomeric catalyst species.

Catalysis↗
PubMed2005

A new entry in catalytic alkynylation of aldehydes and ketones: dual activation of soft nucleophiles and hard electrophiles by an indium(III) catalyst.

[reaction: see text] A new entry in catalytic alkynylation of carbonyl compounds was developed in which dual activation of both soft nucleophiles (terminal alkynes) and hard electrophiles (aldehydes and ketones) is achieved using an indium(III) catalyst. Preliminary mechanistic studies using in situ IR and NMR spectroscopic analysis are also discussed.

Journal Article↗
PubMed2005

Dynamic ligand exchange of the lanthanide complex leading to structural and functional transformation: one-pot sequential catalytic asymmetric epoxidation-regioselective epoxide-opening process.

The characteristic property of the lanthanide complex, which easily undergoes a dynamic ligand exchange and alters its structure and function in situ, is described. After the completion of the catalytic asymmetric epoxidation of various alpha,beta-unsaturated amides 2 in the presence of the Sm-(S)-BINOL-Ph3As=O (1:1:1) complex 1 (2-10 mol %), the addition of Me3SiN3 directly to the reaction mixture led to smooth epoxide-opening at room temperature, affording the corresponding anti-beta-azido-alpha-hydroxyamide 4 in excellent overall yield (up to 99%) with complete regioselectivity and excellent enantiomeric excess (up to >99%). The key to the success of the sequential process was the in situ generation of the highly reactive samarium azide complex through dynamic ligand exchange. In situ IR spectroscopy and other experiments provided strong evidence that the samarium azide complex was generated. In addition, the relatively high Lewis basicity of the amide moiety had a key role in the high reactivity of both the epoxidation and the epoxide-opening reactions. Examinations of other nucleophiles such as sulfur or carbon nucleophiles as well as transformations of epoxide-opened products are also described.

Journal Article↗
PubMed2005

[A case of liver metastases from cecal cancer successfully treated with fluorouracil and folinic acid (UFT/LV)].

A 76-year-old man had undergone a right hemicolectomy for cecal cancer. Oral UFT (450 mg/day) administration alone was started 2 months following the operation. From a CT scan of the abdomen performed 3 months postoperatively, he was diagnosed with liver metastasis. Because the liver metastasis had progressed, combination oral administration of UFT+LV was started (UFT 450 mg/day, LV 75 mg/day, 4 weeks of therapy followed by a 1-week treatment break). After 1 cycle, a good partial response of that lesion was achieved. The pulmonary metastasis had almost disappeared to within normal limits. In conclusion, this treatment was very safe and effective.

Adenocarcinoma↗
PubMed2004

Direct catalytic asymmetric aldol-Tishchenko reaction.

A direct catalytic asymmetric aldol reaction of propionate equivalent was achieved via the aldol-Tishchenko reaction. Coupling an irreversible Tishchenko reaction to a reversible aldol reaction overcame the retro-aldol reaction problem and thereby afforded the products in high enantio and diastereoselectivity using 10 mol % of the asymmetric catalyst. A variety of ketones and aldehydes, including propyl and butyl ketones, were coupled efficiently, yielding the corresponding aldol-Tishchenko products in up to 96% yield and 95% ee. Diastereoselectivity was generally below the detection limit of 1H NMR (>98:2). Preliminary studies performed to clarify the mechanism revealed that the aldol products were racemic with no diastereoselectivity. On the other hand, the Tishchenko products were obtained in a highly enantiocontrolled manner.

Journal Article↗
PubMed2004

Strategy for enantio- and diastereoselective syntheses of all possible stereoisomers of 1,3-polyol arrays based on a highly catalyst-controlled epoxidation of alpha,beta-unsaturated morpholinyl amides: application to natural product synthesis.

We describe a new strategy for enantio- and diastereoselective syntheses of all possible stereoisomers of 1,3-polyol arrays. This strategy relies on a highly catalyst-controlled epoxidation of alpha,beta-unsaturated morpholinyl amides promoted by the Sm-BINOL-Ph(3)As[double bond]O (1:1:1) complex, followed by a conversion of morpholinyl amides into ketones and diastereoselective ketone reduction. Highly enantio- (up to >99 % ee) or diastereoselective (up to >99.5:0.5) epoxidation was achieved using 5-10 mol % of the Sm complex to afford synthetically very useful, nearly optically pure alpha,beta-epoxy morpholinyl amides. Stereoselectivity of the epoxidation was controlled by the chirality of BINOL with overwhelming inherent diastereofacial preference for the substrate. Combination with the syn- and anti-selective ketone reduction with the highly catalyst-controlled epoxidation allowed for an iterative strategy for the syntheses of all possible stereoisomers of 1,3-polyol arrays. Eight possible stereoisomers of 1,3,5,7-tetraol arrays were synthesized with high to excellent stereoselectivity. Moreover, the efficiency of the present strategy was successfully demonstrated by enantioselective syntheses of several 1,3-polyol/alpha-pyrone natural products, for example, cryptocaryolone diacetate.

Alcohols↗
PubMed2004

Enantioselective syntheses and biological studies of aeruginosin 298-A and its analogs: application of catalytic asymmetric phase-transfer reaction.

Aeruginosin 298-A was isolated from the freshwater cyanobacterium Microcystis aeruginosa (NIES-298) and is an equipotent thrombin and trypsin inhibitor. A variety of analogs were synthesized to gain insight into the structure-activity relations. We developed a versatile synthetic process for aeruginosin 298-A as well as several attractive analogs, in which all stereocenters were controlled by catalytic asymmetric phase-transfer reaction promoted by two-center asymmetric catalysts and catalytic asymmetric epoxidation promoted by a lanthanide-BINOL complex. Furthermore, serine protease inhibitory activities of aeruginosin 298-A and its analogs were examined.

Alkylation↗