Masanori Kumagai

Refolding and Activation of Human Prorenin Expressed in Escherichia coli: Application of Recombinant Human Renin for Inhibitor Screening

Human prorenin was expressed in Escherichia coli as a fusion protein of thioredoxin. The chimeric protein, which accumulated insoluble inclusion bodies, was solubilized in 4 M guanidine–HCl and refolded by an arginine-detergent buffer system and by systematic dialysis. The refolded fusion prorenin was activated by trypsin. The antiserum against human kidney renin specifically inhibited the recombinant human renin activity. Using the recombinant human renin, we screened its inhibitory activity in fermented soybean paste (miso) and demonstrated that miso contained renin inhibitory activity derived from soybean. The IC50 values for soybean and steamed soybean extracts were determined to be 1.9 and 1.6 mg/ml, respectively. This is the first demonstration of renin inhibitory activity in miso and soybean.

A chemometrics approach for distinguishing between beers using near infrared spectroscopy

Thirty-eight beers from different producing areas and/or makers were distinguished by principal component analysis (PCA) of the near infrared (NIR) spectra acquired by a portable NIR spectrometer. Classsification of Akita beers: beers locally produced in Akita prefecture, Japan, from other famous brand beers could be successfully performed, especially when the PCA was calculated on the standard normal variate (SNV) spectra. The classification equations use information related to water and CH2 absorption that reflected the differences in chemical com position of beers due to different production processes. In addition, the compositions of total polyphenol and total nitrogen were estimated from NIR spectra by multiple linear regression (MLR). This study showed that NIR spectroscopy is promising for beer quality evaluation, both for identifying multifarious beers including Akita beers using PCA and for rapid in-line quality control and inspection for beer production using the quantitative MLR analysis.

JUNSAIKOMACHI, a dietary supplement with water shield and sake cake

Akita prefecture, located in the northwest of Japan, is famous for the production of sake. Since large amounts of sake cake are generated as a by-product in the manufacturing process, its utilization is an important theme for sake brewing companies, but is still very limited. Water shield (Brasenia schreberi), which is an aquatic plant, and its young buds are used as a food ingredient. Mitane town in north Akita harvests the largest amounts of water shield in Japan; however, the amounts harvested each year have decreased. Based on this background, we have investigated the biological functions of these foodstuffs in an attempt to expand and advance their utilization. Briefly, we prepared dietary supplements with water shield extract (ORYZA OIL & FAT CHEMICAL CO., LTD.) and sake cake dry powder (AKITA MEIJYO CO., LTD.), and examined their effects on defecation by and the skin condition of healthy adult females in double-blind placebo-controlled clinical trials . The administration of dietary supplements for 2 weeks to healthy adult females markedly increased the number of days with defecation as well as defecation frequency over those of the placebo group. The administration of these supplements also appeared to improve fecal strength, shape, and odor as well as the sense of an incomplete evacuat ion by subjects .

Relationships between the expression of hepatocyte nuclear factors and factors essential for lipoprotein production in a human mesenchymal stem cell line, UE7T-13

To clarify the mechanisms regulating lipoprotein production by hepatocyte nuclear factors (HNFs), we generated four kinds of transfectants in human bone marrow mesenchymal stem cells: UE7T-13, stably expressing FOXA2 (also known as HNF3β), HNF4α, HNF1α or co-expressing HNF4α, and HNF1α (HNF4α/HNF1α). In HNF4α/HNF1α transfectants, cellular contents of triglycerides (TG) and cholesterol were markedly higher than in UE7T-13 cells and comparable to those in human hepatoma HepG2 cells. However, TG and cholesterol, which are secreted from cells as components of lipoproteins, were hardly detected in the medium for any of the transfectants. ApoB100 and MTP, which are essential for the formation and secretion of lipoproteins, were undetectable and detected at low levels, respectively, in HNF4α/HNF1α transfectants. We suggest that enforced co-expression of HNF4α and HNF1α is effective for cellular lipid accumulation, while additional factors are probably required for lipoprotein formation and secretion. Graphical Abstract HNF4α and HNF1α are essential for cellular lipid accumulation, while additional factors are probably required for lipoprotein production.