Effect of Water Hardness on Acute Aquatic Toxicity of Fatty Acid Salts.

The acute aquatic toxicity of anionic surfactants, including fatty acid salts, changes depending on water hardness. Generally, the acute aquatic toxicity of Daphnia magna is caused by the adsorption of surfactants and other substances. Despite the low environmental risk, the effect of water hardness on the acute aquatic toxicity of soap should be discussed to improve the assessment accuracy. Previously, we evaluated the effects of water hardness and the presence of an adsorbent on the acute aquatic toxicity of soap by performing an immobility test using D. magna in accordance with Japanese Industrial Standards (JIS) K 0229. Immobility was low at 50 ppm and a higher water hardness was indicated owing to the loss of interfacial activities caused by the formation of insoluble fatty acid calcium or magnesium complexes (soap scum). In the current study, we evaluate the effects of water hardness on the acute aquatic toxicity of C10, C12, C14, C16, and C18 saturated and C18:1 unsaturated fatty acid sodium salts. The EC50 is measured via an immobility test in accordance with JIS K 0229 using D. magna, and the surface tension is measured as an indicator of surface activity. Results show that the EC50 and surface tension curves change with water hardness in single and mixed solutions. C18:1 indicates the least change and the highest surface activity. Moreover, immobility change is not observed when C18:1 is filtered, whereas the immobility of other solutions decreased significantly. This implies the effect of soap scum on immobility, such as the clogging of gills by soap scum. Based on quantitative analysis, the percentage of C18:1 that transformed soap scum to its initial concentration exceeds 80%. This implies that calcium deficiency under 5 and 25 ppm water hardness affects the immobility of larval D. magna. The effects of soap scum clogging and calcium deficiency on D. magna should be considered before assessing the soap.

Classification of the Biodegradation Factors of Linear Alkylbenzene Sulfonate.

The conditions that significantly affect the biodegradability of linear alkylbenzene sulfonate (LAS) based on previous studies were categorized. Among these previous studies, we focused on those that used activated sludge and river water as inocula in biodegradation studies. Analyzing the results of these studies revealed two types of methylene blue active substances (MBAS) removal curves in primary biodegradation, and the study conditions that differentiated the two types were analyzed, along with verification studies. The effects of the LAS concentration and interfacial activity during biodegradation were analyzed to set the concentration of LAS in this study. Surface tension was measured as an indicator of interfacial activity and biodegradation was measured by oxygen demand. Two widely used surfactants, alcohol ethoxylate and sodium dodecyl sulfate, were evaluated to clarify the significance of the effective concentration range of LAS. The concentration of LAS was set at 10 or 20 mg/L in the verification study. Acclimatization and the concentration balance of LAS and river water were the strongest factors in studies using activated sludge and river water, respectively. Our classification chart may be helpful in analyzing and comparing the conditions of previous and current studies. Such understanding of the study conditions and practical evaluation may aid in avoiding misleading environmental impact assessments of LAS.

Laminar flow in microfluidics investigated by spatially-resolved soft X-ray absorption and infrared spectroscopy.

The application of soft X-ray absorption spectroscopy (XAS) to liquid cells based on microfluidics for chemical state analysis of light elements is much more difficult than hard X-ray absorption since soft X-rays cannot deeply penetrate a microfluidic cell. In this study, we have newly developed a microfluidic cell for spatially resolved XAS, where a 100 nm thick Si3N4 membrane is used for the measurement window to transmit soft X-rays for keeping the microfluidic flow at a width and depth of 50 µm. The π* peak of pyridine near the N K-edge XAS shows characteristic energy shifts near the liquid-liquid interface in a laminar flow of pyridine and water. The distributions of the molar fractions of pyridine and water near the liquid-liquid interface have been determined from the energy shifts of the π* peak probed at different geometric positions, where pyridine is mixed in the water part of the laminar flow and vice versa. The spatial distribution of both species has also been studied by infrared microscopy, using the same microfluidic setup. The present work clearly shows that these spectroscopic techniques are easily applicable to chemical and biological reactions prepared by microfluidics.

Surface characteristics and electrical properties of PMMA chips for incubation-type planar-patch-clamp biosensors.

Polymethylmethacrylate (PMMA) plates were successfully applied as sensor chips in an incubation-type planar patch clamp (IPPC). Hot embossing both sides formed the PMMA plates, and a focused ion beam realized micropores. The low seal resistance of the IPPC was investigated by analyzing the surface roughness of the chips. Atomic force microscopy (AFM) showed that the chip surface had a roughness of several nanometers due to the molding process. Coating the molded surface with an anti-adhesive compound further increased the surface roughness of the PMMA chip because the anti-adhesive compound itself had a large roughness and in some case, the compound partially peeled off while detaching the mold. Similarly, coating a chip with extracellular matrix (ECM) poly-l-lysine (PLL) also increased the surface roughness. The measured seal resistance of the PMMA chip for an HEK293 cell was in the range of 4-15 MΩ. The low seal resistance was attributed to the sharp-edge structure of the micropore and the surface roughness of the chip. Nevertheless, the whole cell current was successfully recorded from HEK293 cells expressing channel rhodopsin wide receiver (ChRWR) using salt-bridge-type stable Ag/AgCl electrodes. Another advantage of the PMMA sensor chip was the small parasitic capacitance.

Positioning of the sensor cell on the sensing area using cell trapping pattern in incubation type planar patch clamp biosensor.

Positioning the sensor cell on the micropore of the sensor chip and keeping it there during incubation are problematic tasks for incubation type planar patch clamp biosensors. To solve these problems, we formed on the Si sensor chip's surface a cell trapping pattern consisting of a lattice pattern with a round area 5 µm deep and with the micropore at the center of the round area. The surface of the sensor chip was coated with extra cellular matrix collagen IV, and HEK293 cells on which a chimera molecule of channel-rhodopsin-wide-receiver (ChR-WR) was expressed, were then seeded. We examined the effects of this cell trapping pattern on the biosensor's operation. In the case of a flat sensor chip without a cell trapping pattern, it took several days before the sensor cell covered the micropore and formed an almost confluent state. As a result, multi-cell layers easily formed and made channel current measurements impossible. On the other hand, the sensor chip with cell trapping pattern easily trapped cells in the round area, and formed the colony consisted of the cell monolayer covering the micropore. A laser (473 nm wavelength) induced channel current was observed from the whole cell arrangement formed using the nystatin perforation technique. The observed channel current characteristics matched measurements made by using a pipette patch clamp.

Evaluating home blood pressure in treated hypertensives in comparison with the referential value of casual screening of blood pressure: the Ohasama study.

OBJECTIVE: The target home blood pressure (BP) levels for antihypertensive treatment have not been fully investigated. We estimated home BP values that corresponded to the referential values of casual screening of BP using reduced major axis (RMA) regression for data from untreated and treated individuals in a general population. METHODS: The study included 2651 participants (778 treated) aged 20 years or above. The relationships between casual BP and home BP were examined using RMA regression to consider measurement errors. We calculated estimated home BP values that corresponded to casual BP using the regression equations. RESULTS: Although casual BPs and home BPs were significantly correlated (all: P<0.0001), the coefficients of determination in multiple regression were higher in untreated individuals than those in treated ones. When RMA regression was applied between casual BP (x) and morning home BP (y), the equations were expressed as y=0.78x+26.55 (systolic BP) and y=0.84x+14.34 (diastolic BP) in treated individuals and y=0.79x+19.29 (systolic BP) and y=0.85x+9.94 (diastolic BP) in untreated ones. The estimated home BPs corresponded to 140/90 mmHg of casual BP: 135.8/89.8 mmHg (morning), 132.2/86.6 mmHg (evening), and 133.9/87.8 mmHg (average) in treated individuals and 129.2/86.7 mmHg (morning), 127.8/84.8 mmHg (evening), and 128.2/85.2 mmHg (average) in untreated individuals. CONCLUSION: We estimated the referential values of home BP in treated hypertensives using a regression model; however, further intervention studies on home BP are needed to clarify the target treatment goals of home BP.

Binding properties of Clostridium botulinum type C progenitor toxin to mucins.

It has been reported that Clostridium botulinum type C 16S progenitor toxin (C16S toxin) first binds to the sialic acid on the cell surface of mucin before invading cells [A. Nishikawa, N. Uotsu, H. Arimitsu, J.C. Lee, Y. Miura, Y. Fujinaga, H. Nakada, T. Watanabe, T. Ohyama, Y. Sakano, K. Oguma, The receptor and transporter for internalization of Clostridium botulinum type C progenitor toxin into HT-29 cells, Biochem. Biophys. Res. Commun. 319 (2004) 327-333]. In this study we investigated the binding properties of the C16S toxin to glycoproteins. Although the toxin bound to membrane blotted mucin derived from the bovine submaxillary gland (BSM), which contains a lot of sialyl oligosaccharides, it did not bind to neuraminidase-treated BSM. The binding of the toxin to BSM was inhibited by N-acetylneuraminic acid, N-glycolylneuraminic acid, and sialyl oligosaccharides strongly, but was not inhibited by neutral oligosaccharides. Both sialyl alpha2-3 lactose and sialyl alpha2-6 lactose prevented binding similarly. On the other hand, the toxin also bound well to porcine gastric mucin. In this case, neutral oligosaccharides might play an important role as ligand, since galactose and lactose inhibited binding. These results suggest that the toxin is capable of recognizing a wide variety of oligosaccharide structures.

The economic impact of the introduction of home blood pressure measurement for the diagnosis and treatment of hypertension.

OBJECTIVES: To investigate the economic consequences resulting from introduction of home blood pressure measurement in diagnosis of hypertension instead of casual clinic blood pressure measurement. METHODS: We constructed a decision tree model using data from the Ohasama study and a Japanese national database. The Ohasama study provided the prognostic value of home blood pressure as compared with clinic blood pressure measurement. RESULTS: It is predicted that the use of home blood pressure for hypertension diagnosis results in a saving of 9.30 billion US dollars (1013.6 billion yen) in hypertension-related medical costs in Japan. Most of this was attributable to medical costs saved by avoiding the start of treatment for untreated individuals who were diagnosed as hypertensive by clinic blood pressure but whose blood pressures were in the normal range when based on home blood pressure; that is, the so called white-coat hypertension. Furthermore, it could be expected that adequate blood pressure control mediated by the change in the diagnostic method from clinic to home blood pressure measurement would improve the prognosis for hypertension. We estimated that the prevention of hypertensive complications resulted in a reduction of annual medical costs by 28 million US dollars (3.0 billion yen). In addition, stroke prevention due to adequate blood pressure control based on home blood pressure measurement reduced annual long-term care costs by 39 million US dollars (4.2 billion yen). A per-person break-even cost for introducing home blood pressure monitoring was calculated as 409 US dollars (44,580 yen). CONCLUSIONS: The introduction of home blood pressure measurement for the diagnosis and treatment of hypertension would be very effective to save costs.