Reactions of oxalyl chloride with 1,2-cycloalkanediols in the presence of triethylamine

The relationship between the product patterns and the configurations of 1,2-cycloheptane- and 1,2-cyclooctanediols 9 in the cyclocondensations with oxalyl chloride in the presence of tricthylamine at 0°C has been shown analogous to that obtained for 1,2-disubstituted acyclic ethylene glycols 1: cis-1,2-cyclooctanediol (9f) produced the cyclic oxalate 14f as the major product, while trans-1,2-cycloheptanediol (9e) and trans-1,2-cyclooctanediol (9g) formed the cyclic carbonates 12e, g as the major products. On the other hand, the cyclic oxalates 14a-d were formed as the major products from 1,2-cyclopentane- and 1,2-cyclohexanediols regardless of the configuration. These results can be accounted for by assuming the boat-like transition states for cyclizations of the half esters of comparatively rigid five- and six-membered diols 9a-d. The cyclic oxalates 14a, c may be directly formed through the resulting tetrahedral intermediates from cis-diols (9a, c), and the cyclic carbonates 12a, c as the minor products after ring inversion of the tetrahedral intermediates. The tetrahedral intermediates from the trans-isomers 9b,d cannot undergo ring inversion, producing no traces of the cyclic carbonates 12b,d. © 2002 Pharmaceutical Society of Japan

Efficient synthesis and hydrolysis of cyclic oxalate esters of glycols

Based on the mechanism postulated for the formation of the cyclic carbonates 3 in the reactions of glycols 1 with oxalyl chloride in the presence of triethylamine, we present here three efficient syntheses of the cyclic oxalates 2 of various glycols 1 by controlling the formation of 3: replacement of the base by pyridine markedly diminishes yields of 3 in all reactions, realizing dramatic reversals of the product ratios in the reactions with the (R*,R*)-compounds 1g-i, q, r and pinacol (1k); although considerable amounts of the oxalate polymers are formed in the reactions with some (R*,S*)-glycols, this drawback can be removed by the use of 2,4,6-collidine instead of pyridine; 1,1′-oxalyldiimidazole is useful for the synthesis of two selected cyclic oxalates 2e, f. The cyclic oxalates 2 other than trisubstituted and tetrasubstituted ones were found to be very reactive: kinetic studies on the hydrolysis of 1,4-dioxane-2,3-dione (2a) as well as its mono- and some selected 5,6-disubstituted derivatives 2 have revealed that they undergo hydrolysis 260-1500 times more rapidly than diethyl oxalate (12) in acetate buffer-acetonitrile (pH 5.69) at 25°C. Although the cyclic oxalate 2l from cis-1,2-cyclopentanediol (1l) was 1.5 times more reactive than 2a, it has been shown with other substrates that increasing number of the alkyl substituents decreases the rate of hydrolysis. On the contrary, the phenyl group was found to have somewhat accelerative effect. © 2002 Pharmaceutical Society of Japan

Efficient depolymerization of polyethylene terephthalate (PET) and polyethylene furanoate by engineered PET hydrolase Cut190

The enzymatic recycling of polyethylene terephthalate (PET) can be a promising approach to tackle the problem of plastic waste. The thermostability and activity of PET-hydrolyzing enzymes are still insufficient for practical application. Pretreatment of PET waste is needed for bio-recycling. Here, we analyzed the degradation of PET films, packages, and bottles using the newly engineered cutinase Cut190. Using gel permeation chromatography and high-performance liquid chromatography, the degradation of PET films by the Cut190 variant was shown to proceed via a repeating two-step hydrolysis process; initial endo-type scission of a surface polymer chain, followed by exo-type hydrolysis to produce mono/bis(2-hydroxyethyl) terephthalate and terephthalate from the ends of fragmented polymer molecules. Amorphous PET powders were degraded more than twofold higher than amorphous PET film with the same weight. Moreover, homogenization of post-consumer PET products, such as packages and bottles, increased their degradability, indicating the importance of surface area for the enzymatic hydrolysis of PET. In addition, it was required to maintain an alkaline pH to enable continuous enzymatic hydrolysis, by increasing the buffer concentration (HEPES, pH 9.0) depending on the level of the acidic products formed. The cationic surfactant dodecyltrimethylammonium chloride promoted PET degradation via adsorption on the PET surface and binding to the anionic surface of the Cut190 variant. The Cut190 variant also hydrolyzed polyethylene furanoate. Using the best performing Cut190 variant (L136F/Q138A/S226P/R228S/D250C-E296C/Q123H/N202H/K305del/L306del/N307del) and amorphous PET powders, more than 90 mM degradation products were obtained in 3 days and approximately 80 mM in 1 day

Population genomics of the fission yeast Schizosaccharomyces pombe.

The fission yeast Schizosaccharomyces pombe has been widely used as a model eukaryote to study a diverse range of biological processes. However, population genetic studies of this species have been limited to date, and we know very little about the evolutionary processes and selective pressures that are shaping its genome. Here, we sequenced the genomes of 32 worldwide S. pombe strains and examined the pattern of polymorphisms across their genomes. In addition to introns and untranslated regions (UTRs), intergenic regions also exhibited lower levels of nucleotide diversity than synonymous sites, suggesting that a considerable amount of noncoding DNA is under selective constraint and thus likely to be functional. A number of genomic regions showed a reduction of nucleotide diversity probably caused by selective sweeps. We also identified a region close to the end of chromosome 3 where an extremely high level of divergence was observed between 5 of the 32 strains and the remain 27, possibly due to introgression, strong positive selection, or that region being responsible for reproductive isolation. Our study should serve as an important starting point in using a population genomics approach to further elucidate the biology of this important model organism

Hepatocyte apoptosis is enhanced after ischemia/reperfusion in the steatotic liver

Liver steatosis is associated with organ dysfunction after hepatic resection and transplantation which may be caused by hepatic ischemia/reperfusion injury. The aim of the current study was to determine the precise mechanism leading to hepatocyte apoptosis after steatotic liver ischemia/reperfusion. Using a murine model of partial hepatic ischemia for 90 min, we examined the levels and pathway of apoptosis, and the peroxynitrite expression, serum alanine aminotransferase levels, and liver histology 1 and 4 h after reperfusion. In the steatotic liver, the peroxynitrite expression increased after ischemia/reperfusion. Significant hepatocyte apoptosis in the steatotic liver was seen after reperfusion, caused by upregulation of cleaved caspases 9 and 3, but not caspase 8. Serum alanine aminotransferase levels were elevated and histological examination revealed severe liver injury in the steatotic liver 4 h after reperfusion. In mice treated with aminoguanidine, ischemia/reperfusion-induced increases in serum alanine aminotransferase levels and apoptosis were significantly reduced in steatotic liver compared with mice treated with phosphate buffered saline. Survival of mice with steatotic livers significantly improved by treatment with aminoguanidine. Our data suggested that the steatotic liver is vulnerable to hepatic ischemia/reperfusion, leading to significant hepatocyte apoptosis by the mitochondrial permeability transition, and thereby resulting in organ dysfunction

Spontaneous regression of bone metastasis from renal cell carcinoma; A case report

BACKGROUND: Spontaneous regression of metastatic renal cell carcinoma is rarely observed. CASE PRESENTATION: Metastatic renal cell carcinoma was identified in a 70-year-old male using computed tomography-guided percutaneous needle biopsy. Two months after the diagnosis, a partial resection of the sternal bone was performed. Pathological examination revealed granulated tissue with bleeding and necrosis but no carcinogenic cells. CONCLUSION: We report a pathologically identified case in which a sternal bone metastasis that was noticed two years after radical nephrectomy regressed completely and spontaneously

新しい介護負担評価尺度(ABC-16)の妥当性

目的：本研究の目的は、新たに作成された自己記入式介護負担評価尺度(ABC-16) の妥当性を検討することである方法：対象者は、第1群では51名（平均年齢63±11歳）、第2群では31名（平均年齢58±14歳）の家族介護者である。結果：第1群におけるABC-16総計の平均点は14.98±7.52であった。第1群では高い妥当性（内的整合性、α=0.821) を示し、かつ4つの領域間に有意の相関が得られた(P<0.05)。重回帰分析によりABC-16と介護者のQOL (P=0.034) および夜間介護(P=0.001) とにおいて強い関連が見られた。第2群は第1群の結果とほぽ同様の結果が得られ、ABC-16の交差妥当性のあることが示唆された。結論： ABC-16は高い妥当性を有する大変優れた介護負担評価尺度であることが示された。Aims: The aim of this study is to evaluate the validation of a newly developed self-administered assessment of the burden on caregivers (ABC-16). Methods: The subjects were 51 family caregivers (mean age 63 ± 11 years) for the first trial and 31 family caregivers (mean age 58 ± 14 years) for the second trial. The ABC-16 consists of 16 items and is designed to cover 4 dimensions (the care receiver\u27s burden, burden on social life, financial burden, and burden on health). Results: In the first trial, the mean and standard deviation of the total score of the ABC-16 was 14.98 ± 7.52. The first trial showed high reliability; the internal consistency was α=0.821 and significant correlations among the four dimensions were found (P<0.05). A multiple regression analysis showed strong correlations between the ABC-16 and the QOL of the caregivers (P=0.034), and the caregiving during the night (P=0.001). The second trial showed findings similar to those in the first trial, which suggested the good cross validation of the ABC-16. Conclusions: It is suggested that the ABC-16 is an excellent tool for assessing the care burden with high validity

Treatment of multiple liver metastasis from gastric carcinoma

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