Strain selection and scale-up fermentation for FR901379 acylase production by Streptomyces sp. no. 6907

Micafungin (FK463) is a widely used treatment for life-threatening, deep-seated fungal infections. It is an echinocandin-like lipopeptide derived from the chemical modification of deacylated FR901379, a type of lipopeptide antibiotic produced by Coleophoma empetri F-11899. The palmitoyl moiety of FR901379 is deacylated by FR901379 acylase produced by Streptomyces sp. no. 6907. In this study, our goal was to generate an improved strain of Streptomyces sp. no. 6907 capable of hyperproducing the FR901379-acylase enzyme. To accomplish this goal, modified strains of Streptomyces sp. no. 6907 were generated using UV-irradiation mutagenesis, and strain selection was performed using an agar-plate screening method to efficiently select an acylase-hyperproducing strain. Three marker indices were shown to correlate with elevated acylase production: decreased candidacidal activity of FR901379, decreased proteolytic activity on skim milk, and phenotypic characteristics. Cloning and subsequent sequencing of the acylase gene from the hyperproducing mutant revealed no mutations in either the acylase structural gene or the 5'-flanking region required for gene expression. The growth medium was also modified to maximize acylase production. We successfully increased acylase activity approximately 65-fold, compared with the original growth conditions (wild strain cultured in the original unmodified medium). To minimize formation of excess foam during the fermentation process, we optimized the parameters of agitation speed, as calculated from the discharge flow rate. Using our improved strain and the optimized medium and growth conditions, we have developed an improved and highly reproducible method for stable large-scale production of FR901379-acylase.     

Double-action bending for eliminating springback in hat-shaped bending of advanced high-strength steel sheet

The International Journal of Advanced Manufacturing Technology - This paper presents a novel technology called ‘double-action bending (DAB)’ to eliminate springback in hat-shape forming...     

Epidemiology of genotypes of hepatitis C virus in Japanese patients with type C chronic liver diseases: a multi-institution analysis

Sixteen medical institutions in Japan collaborated in this study of the epidemiology of hepatitis C virus (HCV) genotypes. A total of 4176 patients with type C chronic liver disease, from the four main islands of Japan, were evaluated. Of those evaluated, 2794 had chronic hepatitis, 727 had liver cirrhosis and 655 had hepatocellular carcinoma. The HCV genotype of the patients was determined by an enzyme-linked immunosorbent assay based on serological genotype 1- and 2-specific recombinant peptides (SG-1 and SG-2, respectively) of the NS4 region. The prevalence of SG-1 and SG-2 HCV was similar in the four main islands of Japan. SG-1 HCV predominated in each disease category (69-76%). The percentage of patients with SG-1 HCV increased by 7%, while that of patients with SG-2 HCV decreased by 7%, as liver disease progressed in severity from chronic hepatitis to carcinoma (P < 0.001). Patients with either SG-1 or SG-2 had a similar mean age and history of blood transfusion. In conclusion, SG-1 HCV was found to predominate in Japan, and the HCV genotype was found to be related to the stage of hepatitis C disease.     

Multigigabit multichannel optical interconnection module forbroadband switching system

This paper describes optical transmitter and receiver modules for package-to-package interconnection in broadband switching networks such as an asynchronous transfer mode switch fabric. These modules, which include the multiplexer and demultiplexer, can reduce the number of connections and the problem of skew between links. Five-channel optical transmitter and receiver modules were fabricated and demonstrated at 2.8 Gbit/s with a power dissipation of 4.5 W per channel. Moreover, temperature-insensitive optical interconnection was successfully demonstrated by driving a laser with a constant bias current over the threshold and by deducting the optical signal offset. The output power of the transmitter module was -4.2 dBm. Nonuniformity of the transmitter output powers across the range of optical channels was <2.1 dB. Receiver sensitivity for a bit error rate of 10^-11 was -9.3 dBm. Nonuniformity of the receiver sensitivities was <1.5 dB. The power penalty of the receiver sensitivity due to crosstalk was 1 dB. The connection distance was >250 m     

An experimental technique for obtaining controlled diagonal tension failure of shear critical reinforced concrete beams

An energy absorbing ‘stiff’ test facility has been developed for obtaining stable and controlled diagonal tension failure in shear-critical reinforced concrete beams. The test facility allows the monitoring of the complete curve of load versus mid-span deflection (including the post-peak region) of the shear-critical beams. For stiffening the existing test facility and to provide the energy absorption capability, two kinds of test set-up have been developed: the parallel steel beam test set-up and the cross steel beam test set-up. The test set-up with a cross steel beam as the stiffening element is much stiffer than the parallel steel beam test set-up and hence more stable for obtaining a controlled and stable failure even for the higher strengh concrete beams. The results indicate the post-peak branch of the load versus mid-span deflection of the shear-critical high strength concrete beams is relatively steeper than that of normal strength concrete beams.     

Enzymatic resolution of planar chiral ferrocene derivatives

Racemic 3-methyl, 2-ethyl, 2-bromo, and 2-trimethylsilyl derivatives of formylferrocene were kinetically resolved by enantioselective reduction with a fermenting baker's yeast. Moreover, 2-methyl, 3-methyl, 2-ethyl, 2-bromo, and 2-trimethylsilyl derivatives of hydroxymethylferrocene were optically resolved with lipases by transesterification using vinyl esters.     

7-(2-Aminomethyl-1-azetidinyl)-4-oxoquinoline-3-carboxylic acids as potent antibacterial agents: design, synthesis, and antibacterial activity

2-Aminomethyl-1-azetidinyl, -1-pyrrolidinyl, and -1-piperidinyl groups were designed as novel C-7 substituents for potential antibacterial quinolone agents. Of the three substituents, the 2-aminomethyl-1-azetidinyl group (compound 12a) was found to be the most favorable for enhancing the activity of the 6,8-difluoroquinoline molecule 12. Therefore the 2-aminomethyl-1-azetidinyl group was introduced into a variety of quinolines (giving 24-26a, and 28a) and naphthyridines (giving 31a and 32a). Through optical resolution of 1-benzylazetidine-2-carboxamide (19) and chiral synthesis of its R-isomer, both enantiomers of 2-aminomethyl-1-azetidinyl quinolines 12a and 24-26a were also prepared. The most active of all the compounds was 5-amino-6,8-difluoroquinoline (R)-26a. The activity of (R)-26a was more potent than those of the corresponding 1-piperazinyl derivative (3) and sparfloxacin (1), and was comparable to those of the corresponding 3-amino-1-pyrrolidinyl (4), 3-aminomethyl-1-pyrrolidinyl (5), and 3-amino-1-azetidinyl (6) derivatives.     

Structure and formation process of (K,Na)-clinoptilolite

In order to synthesize (K,Na)-clinoptilolite, a (K,Na)-aluminosilicate slurry with a seed crystal was stirred at 30 °C for 4 days and then hydrothermally treated under homogeneous mixing conditions at 120 °C for 14 days. The Si/Al:(Na+K)/Si:K/(Na+K):H₂O/Al molar ratio of the starting materials was 6.0:0.42:0.5:52.5. The formation process of (K,Na)-clinoptilolite was investigated by a variety of techniques. When the materials were hydrothermally treated up to 6 days, amorphous (K,Na)-aluminosilicate was formed. After the hydrothermal treatment for 8 days, irregular particles due to the amorphous (K,Na)-aluminosilicate disappeared and plate-like particles of (K,Na)-clinoptilolite were formed, indicating that the amorphous aluminosilicate crystallized as clinoptilolite. In addition, (Na+K)/Al molar ratio in the materials varied from 1.2 to 1.0, accompanying the decrease of cation exchange capacity. During the crystallization, the wavenumber of external linkages of TO bonds shifted to higher values, implying that the SiOSi and SiOAl bonds were formed.     

Hemodynamic disturbances in cerebral ischemia: correlation between positron emission tomographic and angiographic findings

Proper treatment of ischemic stroke requires better understanding of cerebral hemodynamic changes. The hemodynamic changes associated with ischemia were measured using positron emission tomography and related to angiographic findings in the subacute and chronic stages of 17 ischemia patients who showed symptoms of main trunk stenosis of the internal carotid artery system. The hemodynamic factors, cerebral blood flow, cerebral blood volume, cerebral metabolic rate for oxygen, oxygen extraction fraction, and flow/volume ratio, were measured in regions of interest determined from the angiographic stenosis (over 50%) and compared in each stage. The cerebral blood flow and flow/volume ratio in the territory downstream of the main trunk stenosis and cerebral metabolic rate for oxygen in the whole cortex were decreased in the subacute stage. In the chronic stage, cerebral blood flow and flow/volume ratio decreased mainly in borderzone areas.