Search

Studies on the conditions and pollution routes of antibiotic-resistant bacteria (ARB) in rivers can help provide countermeasures against the spread of ARB. This study focused on the pristine uppermost stream of a river, where Escherichia coli (E. coli) and enterococci were detected, although the stream flows through a pristine forest catchment. Antibiotic resistance of E. coli and enterococci isolated from the river water, riverbed sediment, and feces of waterside animals, such as birds and Mustelidae, were investigated throughout the year in the pristine uppermost sites. Antibiotic resistance was present in 1.4% (7/494) of the E. coli strains and 3.0% (24/812) of the enterococcal strains, and was low throughout the year. Although antibiotic resistance of bacteria isolated from feces was not detected in this watershed, the prevalence of multidrug-resistant E. coli was 0.4% (1/246) and 0.6% (1/172) in river water and riverbed sediment samples, respectively were observed. The presence of extended-spectrum β-lactamase (ESBL)-producing E. coli was confirmed in river water samples, and genomic analysis revealed that the samples possessed the CTX-M-15 group. Multidrug-resistant strains and ESBL-producing strains were classified as phylogroups B1 and A, respectively, which are E. coli phenotypes isolated from wild animals. Pulsed-field gel electrophoresis revealed analysis targeting enterococci that strains isolated from river water and bird feces were in the same cluster with 100% similarity. Therefore, bird feces are a source of enterococci in the uppermost stream of the river. Because multidrug-resistant bacteria and ESBL-producing bacteria were present in the pristine uppermost stream of the pristine river, urgent elucidation of the spreading routes of ARB is important.

Besides the fission–fusion dynamics, the cellular distribution of mitochondria has recently emerged as a critical biological parameter in regulating mitochondrial function and cell survival. We previously found that mitochondrial clustering on the nuclear periphery, or monopolar perinuclear mitochondrial clustering (MPMC), accompanies the anticancer activity of air plasma-activated medium (APAM) against glioblastoma and human squamous cell carcinoma, which is closely associated with oxidant-dependent tubulin remodeling and mitochondrial fragmentation. Accordingly, this study investigated the regulatory roles of nitric oxide (NO) in the anticancer activity of APAM. Time-lapse analysis revealed a time-dependent increase in NO accompanied by MPMC. In contrast, APAM caused minimal increases in MPMC and NO levels in nontransformed cells. NO, hydroxyl radicals, and lipid peroxide levels increased near the damaged nuclear periphery, possibly within mitochondria. NO scavenging prevented tubulin remodeling, MPMC, perinuclear oxidant production, nuclear damage, and cell death. Conversely, synthetic NO donors augmented all the prodeath events and acted synergistically with APAM. Salinomycin, an emerging drug against multidrug-resistant cancers, had similar NO-dependent effects. These results suggest that APAM and salinomycin induce NO-dependent cell death, where MPMC and oxidative mitochondria play critical roles. Our findings encourage further investigations on MPMC as a potential target for NO-driven anticancer agents against drug-resistant cancers.

From the biota beneath the sea ice in Lake Saroma, which is adjacent to Sea of Okhotsk, a diatom culture of Saroma 16 was isolated. Strutted processes and a labiate process in Saroma 16 were characteristic of those in Thalassiosira nordenskioeldii. Similarity search analysis showed that the 826-bp rbcL-3P region sequence of this strain was 100% identical to multiple sequences registered as T. nordenskioeldii in a public database. The 4305-bp PCR-amplified mitochondrial cytochrome c oxidase subunit I (COI) gene (COI)-5P region of Saroma 16 included a 1060-bp open reading frame (ORF), which was interrupted by 934-bp and 2311-bp introns that included frame-shifted ORFs encoding reverse-transcriptase (RTase)-like proteins. Previous reports showed that a strain of the same species, CNS00052, originating from the East China Sea included no introns in the COI, whereas North Atlantic Ocean strains of the same species, such as CCMP992, CCMP993, and CCMP997, included a 2.3-kb intron in the same position as Saroma 16.

Hydrological alterations by dams and climate change can reduce aquatic biodiversity by disrupting the life cycles of organisms. Here, we aimed to evaluate and compare the hydrological alterations caused by dams and climate change throughout the Omaru River catchment, Japan, using a distributed hydrological model (DHM). First, to assess the impacts of dam and climate change independently, we performed runoff analyses using either dam discharge or future climatic data (two future periods, 2031–2050 and 2081–2100 × three representative concentration pathways). Subsequently, we derived indicators of hydrologic alterations (IHA) to quantify changes in flow alterations by comparing them to IHA under natural conditions (i.e., without dam or climate change data). We found that dams altered IHAs more than climate change. However, on a catchment-scale standpoint, climate change induced wider ranges of flow alterations, such as a further decrease in low flow metrics along the tributaries and uppermost main stem, suggesting a catchment-level shrinkage in important corridors of aquatic organisms. We also observed that the altered flow by water withdrawals was ameliorated by the confluence of tributaries and downstream hydropower outflows. Our approach using a DHM captured the various patterns of flow alterations by dams and climate change. HIGHLIGHTS The hydrologic model is used to assess flow alterations by dams and climate change.; Compared with climate change, dams altered most environmental flow metrics.; Climate change decreased low flow metrics in upland streams and tributaries.; Ameliorations of the natural flow regime by hydropower outflows remained insufficient.; Prediction of spatial patterns of flow regime alterations is useful to river managers.;

In the ballasted flocculation, high-speed sedimentation of suspensions is achieved using a microsand as a ballast material and a polymer flocculant combined with microflocs made of polyaluminum chloride (PAC) as an inorganic coagulant. In this study, three turbid water samples containing kaolin clay (kaolin concentration: 20, 200, and 500 mg/L) were treated by coagulation–sedimentation and ballasted flocculation. The effects of pH and PAC dosage, which are the controlling parameters for coagulation, and the microsand (silica sand) and polymer dosages, which are the controlling parameters for ballasted treatment, on the treatment efficiency and floc settling velocity were examined. The floc settling velocity under the optimum conditions was 17 times higher than that of the conventional coagulation–sedimentation process using PAC. The turbidity was 0.54 turbidity unit (TU) (TU as the kaolin standard), and its removal efficiency was 99.7%. Furthermore, turbid water samples with different kaolin concentrations (20 and 500 mg/L) were treated via the ballasted flocculation. In this study, fundamental information on the optimization of each dosage condition of coagulant, ballast, and polymer and pH condition in ballasted flocculation was obtained, and the removal mechanisms under optimal, underoptimistic and overoptimistic conditions were proposed. HIGHLIGHTS Conditions for ultrahigh-speed ballast flocculation were investigated.; Floc settling velocity increased and showed a peak at 10 g/L of microsand.; Excess addition of microsand significantly reduced the floc settling velocity.; Hugh floc settling velocity was achieved in the treatment of high-turbidity water.;

Cigarette smoke has been recognized as a major risk factor for cardiovascular disease. However, its direct effects on rodent and human cardiomyocytes and its cellular mechanisms are not fully understood. In this study, we examined the direct effects of cigarette smoke extract (CSE) on contractile functions, intracellular Ca2+ dynamics, and mitochondrial function using cultured or freshly isolated rat ventricular myocytes and human induced pluripotent stem cell (iPS)-derived cardiomyocytes. In rat cardiomyocytes, CSE (≥0.1%) resulted in a time- and concentration-dependent cessation of spontaneous beating of cultured cardiomyocytes, eventually leading to cell death, which indicates direct toxicity. In addition, 1% CSE reduced contractile function of freshly isolated ventricular myocytes. Similar contractile dysfunction (declined spontaneous beating rate and contractility) was also observed in human iPS-derived cardiomyocytes. Regarding intracellular Ca2+ dynamics, 1% CSE increased the Ca2+ transient amplitude by greatly increasing systolic Ca2+ levels and slightly increasing diastolic Ca2+ levels. CSE also accelerated the decay of Ca2+ transients, and triggered spike-shaped Ca2+ transients in some cells. These results indicate that CSE causes abnormal Ca2+ dynamics in cardiomyocytes. Furthermore, CSE induced a cascade of mitochondrial dysfunctions, including increased mitochondrial reactive oxygen species, opening of mitochondrial permeability transition pore, reduction of mitochondrial membrane potential, and release of cytochrome c from mitochondria. These results suggest that CSE-induced contractile dysfunction and myocardial cell death is caused by abnormal Ca2+ dynamics and subsequent mitochondrial dysregulation, which would result in reduced bioenergetics and activation of cell death pathways.

Cold atmospheric plasmas and plasma-treated solutions (PTSs) have emerged as promising approaches in cancer treatment because of their tumor-selective actions. While oxidative stress is critical for their effects, the precise mechanisms, including chemical mediators, remain obscure. Previously, we reported that air plasma-activated medium (APAM) exhibited tumor-selective anticancer activity. The fragmentation of mitochondria and their asymmetrical assembly around the peripheral regions of the damaged nucleus, namely, monopolar perinuclear mitochondrial clustering (MPMC), proceed to the effect. Subsequently, we found that APAM had a substantial amount of O3 in addition to hydrogen peroxide (H2O2), nitrile (NO2-), and nitrate (NO3-). In the present study, we investigated the possible role of O3 in the anticancer effect. For this purpose, we created a nitrogen oxide-free ozonated medium ODM. ODM exhibited potent cytotoxicity against various cancer but not nonmalignant cells. ODM also increased MPMC, hydroxyl radicals, lipid peroxides, and their shifts to perinuclear sites in cancer cells. Catalase and iron chelation prevented these events and cytotoxicity. ODM also decreases the intracellular labile irons while increasing those within mitochondria. ODM had substantial H2O2, but this oxidant failed to cause MPMC and cytotoxicity. These results show that ODM can mimic the effects of APAM, including MPMC and tumor-selective anticancer effects. The findings suggest that O3 is critical in mediating the anticancer effects of APAM by triggering oxidative cell death caused by H2O2 and iron.

Abstract Efficient desalination through a reverse osmosis (RO) membrane requires the prior removal of blockade-causing substances from raw seawater. To achieve ultrahigh-speed processing of a pretreatment process for seawater RO desalination, we combine traditional softening with ballasted flocculation (SBF) for Ca2+ and Mg2+ removal. An alkaline mixture of Ca(OH)2 and Na2CO3 was the most suitable softening agent for Ca2+ and Mg2+ removal with a reduced amount of generated sludge. This softening treatment simultaneously removed the suspended solids and bacteria from actual seawater. The settling velocity of the suspended solids generated via seawater softening was extremely low. Under the optimum conditions for desalinating actual seawater using an anionic polymer flocculant and microsand, the settling velocity exceeded 3.5 cm/s, 833 times higher than that of softening without ballasted flocculation. The amount of sludge after standing for 3 min was 76.5% lower in SBF than in conventional softening. The silt density index of the treated seawater met the water-supply standard of RO membranes (i.e.,

Enterococcus spp. are common bacteria present in the intestinal tracts of animals and are used as fecal indicators in aquatic environments. On the other hand, enterococci are also known as opportunistic pathogens. Elucidating their composition in the intestinal tracts of domestic animals can assist in estimating the sources of fecal contamination in aquatic environments. However, information on the species and composition of enterococci in animal hosts (except humans) is still lacking. In this study, enterococci were isolated from the feces of cattle, pigs, birds, and humans using selective media. Enterococcal species were identified using mass spectrometry technology, and each host was characterized by diversity and cluster analysis. The most dominant species were E. hirae in cattle, E. faecium in birds, and E. faecalis in pigs and humans. Cattle had the highest alpha diversity, with high interindividual and livestock farm diversity. The dominant enterococcal species in pigs and humans were identical, and cluster analysis showed that the majority of the two hosts’ species clustered together.

There is a need for developing a simple and easy-to-maintain disinfection technique for sewage treatment for use in developing countries and disaster-affected areas. We propose a novel disinfection technology that inactivates bacteria in wastewater via sunlight irradiation under high salt concentration by mixing with seawater. The disinfection efficiency of the proposed method was quantitatively evaluated and examined using fecal indicator bacteria. When the salinity in wastewater was adjusted to 30 practical salinity units by mixing with seawater, the constant of inactivation irradiation energy Ks (m2/MJ) was 1.6–2.2-fold greater than that without seawater for total coliforms and Escherichia coli. By contrast, although enterococci were inactivated by sunlight irradiation, an increase in salinity did not enhance disinfection. On setting the irradiation energy of sunlight to 5.5 MJ/m2, >99% of the fecal indicator bacteria were inactivated. Finally, we examined the relationship between the attenuation of irradiance and water depth and accordingly proposed a design of a treatment system wherein wastewater and seawater were adequately mixed and passed via a disinfection tank under the natural flow with sunlight irradiation. HIGHLIGHTS Quantitative evaluation of the appropriate salinity in wastewater mixed with seawater.; Inactivation of fecal indicator bacteria by sunlight with seawater mixing.; Disinfection process based on irradiance and the water depth.; Proposed disinfection is extremely simple and environmentally friendly.;

Abstract On recreational sandy beaches, there are guidelines for the management of bacterial pollution in coastal waters regarding untreated sewage, urban wastewater, and industrial wastewater. However, terrestrial plant debris on coastal beaches can be abundant especially after floods and whilst it has rarely been considered a concern, the bacterial population associated with this type of pollution from the viewpoint of public health has not been adequately assessed. In this study, microbes associated with plant debris drifting onto Kizaki Beach in Japan were monitored for 8 months throughout the rainy season, summer, typhoon season, and winter. Here we show that faecal-indicator bacteria in the plant debris and sand under the debris were significantly higher than the number of faecal bacteria in the sand after a 2015 typhoon. When we focused on specific pathogenic bacteria, Brevundimonas vesicularis and Pseudomonas alcaligenes were commonly detected only in the plant debris and sand under the debris during the survey period. The prompt removal of plant debris would therefore help create safer beaches.

High counts of bacteria are present in beach sand, and human health threats attributable to contact with sand have been reported. In this study, we investigated fecal indicator bacteria in the top surface sand of coastal beaches. Monitoring investigations were performed during a monsoon when rainfall occurs randomly, and the composition of the coliforms was analyzed. The coliform count in the top surface sand (depth < 1 cm) increased by approximately 100 fold (26–2.23 × 103 CFU/100 g) with increasing water content because of precipitation. The composition of the coliforms in the top surface sand changed within 24 h of rainfall, with Enterobacter comprising more than 40% of the coliforms. Estimation of factors that changed the bacterial counts and composition revealed that coliform counts tended to increase with increasing water content in the top surface sand. However, the abundance of Enterobacter was independent of the sand surface temperature and water content. Coliform counts in the top surface sand rapidly increased and the composition showed remarkable variations because of the supply of water to the beach following rainfall. Among them, some bacteria with suspected pathogenicity were present. Controlling bacteria in coastal beaches is important for improving public health for beachgoers.

Abstract The dissemination of antimicrobial-resistant bacteria in environmental water is an emerging concern in medical and industrial settings. Here, we analysed the antimicrobial resistance of Escherichia coli isolates from river water and sewage by the use of a combined experimental phenotypic and whole-genome-based genetic approach. Among the 283 tested strains, 52 were phenotypically resistant to one or more antimicrobial agents. The E. coli isolates from the river and sewage samples were phylogenetically indistinguishable, and the antimicrobial-resistant strains were dispersedly distributed in a whole-genome-based phylogenetic tree. The prevalence of antimicrobial-resistant strains as well as the number of antimicrobials to which they were resistant were higher in sewage samples than in river samples. Antimicrobial resistance genes were more frequently detected in strains from sewage samples than in those from river samples. We also found that 16 river isolates that were classified as Escherichia cryptic clade V were susceptible to all the antimicrobials tested and were negative for antimicrobial resistance genes. Our results suggest that E. coli strains may acquire antimicrobial resistance genes more frequently and/or antimicrobial-resistant E. coli strains may have higher rates of accumulation and positive selection in sewage than in rivers, irrespective of their phylogenetic distribution.

In lactating animals, the food consumption increases several-fold for milk supply to the pups. The present study was conducted to clarify the relationship between the hyperphagia during lactation and hypothalamic leptin receptor (Ob-Rb) mRNA expression, cerebrospinal fluid (CSF) and circulating leptin and glucose levels. Food intakes significantly higher in lactation than in non-lactation at all time points (3 points: light phase, 4 points: dark phase) of the day. However, the expression of the hypothalamic Ob-Rb mRNA showed similar circadian rhythms in both the non-lactation and lactation, with only slight differences between the two groups. CSF leptin and glucose levels were constant throughout the day in both non-lactation and lactation, and there was almost no difference between the two groups at each time point. Circulating leptin and glucose levels showed circadian rhythms only in the non-lactating period, and were lower in lactation than in non-lactation, especially in the dark phase. In conclusion, the present study provides evidence that Ob-Rb mRNA expression fluctuates in the lactation period as well as in the non-lactation period, suggesting that the expression profile of whole hypothalamic Ob-Rb may not contribute to the difference in food consumption between lactation and non-lactation, and that chronic decrease in blood glucose levels may be associated with the increase in food consumption during lactation.

Non-thermal atmospheric pressure plasma (NTAPP)-activated liquids have emerged as new promising anticancer agents because they preferentially injure malignant cells. Here, we report plasma-activated infusion (PAI) as a novel NTAPP-based anti-neoplastic agent. PAI was prepared by irradiating helium NTAP to form a clinically approved infusion fluid. PAI dose-dependently killed malignant melanoma and osteosarcoma cell lines while showing much lower cytotoxic effects on dermal and lung fibroblasts. We found that PAI and salinomycin (Sal), an emerging anticancer stem cell agent, mutually operated as adjuvants. The combined administration of PAI and Sal was much more effective than single-agent application in reducing the growth and lung metastasis of osteosarcoma allografts with minimal adverse effects. Mechanistically, PAI explicitly induced necroptosis and increased the phosphorylation of receptor-interacting protein 1/3 rapidly and transiently. PAI also suppressed the ambient autophagic flux by activating the mammalian target of the rapamycin pathway. PAI increased the phosphorylation of Raptor, Rictor, and p70-S6 kinase, along with decreased LC3-I/II expression. In contrast, Sal promoted autophagy. Moreover, Sal exacerbated the mitochondrial network collapse caused by PAI, resulting in aberrant clustering of fragmented mitochondrial in a tumor-specific manner. Our findings suggest that combined administration of PAI and Sal is a promising approach for treating these apoptosis-resistant cancers.

Background: Asthma often coexists with chronic rhinosinusitis (CRS). Recent studies revealed that sinus inflammation in asthmatic patients was related to eosinophilic inflammation. However, the relationship between the severity of CRS and four different sputum inflammatory phenotypes as defined by the proportion of eosinophils and neutrophils is unknown. The aim of this study was to examine the impact of the severity of CRS on lower airway and systemic inflammation in asthmatic patients. Methods: We enrolled 57 adult asthmatic patients who underwent sinus computed tomography (CT). The severity of CRS was evaluated by the Lund-Mackay score (LMS). The induced sputum inflammatory phenotype was defined by eosinophils (≥/

Abstract This work aims to clarify mismatches between the health condition of residents of the Elderly Housing with Supportive Services (EHSS) and quality of dwelling unit to understand how to improve the quality of the living environment. This work reviews development trends in EHSS and population growth to understand the difficulties faced in improving EHSS in the community. Data were collected from the information disclosure system on the WEB site and through a questionnaire survey of EHSS management bodies. Although residents in regions with large populations have more variety, the plan‐service types available in smaller regions had disproportionately high amounts of room types with moderate to high care, despite that distribution of residents’ necessary care levels were constant across region size. Development of EHSS for self‐supporting residents or those needing mild care is a necessity. Mismatches also emerged between health condition, household size, and degree of care. Many couples were living in R‐housing, displaying a difficulty in EHSS to meet the needs of couples who wish to continue living together. Many residents able to live independently are living in R‐housing, restricting their daily living activities, and presenting a risk of losing the motivation to live.

The environmental DNA (eDNA) method is being increasingly applied in various environments. Although eDNA undergoes rapid degradation in aqueous environments, it has been detected in streams up to 10 km downstream from its source. As environmental bacteria can uptake free DNA, transfer their genetic traits, and amplify, there is a potential risk that they, rather than a target aquatic species, could become a source of measured eDNA. This study examined whether bacteria with incorporated fish DNA could be such a source by investigating the detectability of fish DNA generated by bacteria inhabiting river water and riverbed sediment. We attempted to detect common carp (Cyprinus carpio) eDNA in stream water and sediment samples and the DNA of common carp produced by bacterial colonies (Escherichia coli, total coliform, and heterotrophic bacteria) cultured from the samples. The eDNA was detected in the environmental samples but the carp DNA from the targeted bacteria was rarely detected in both water and riverbed sediment samples. Our results suggest that the risk of bacterium-induced false positive detection for fish eDNA is negligible.

Escherichia coli is classified into four major phylogenetic groups (A, B1, B2, and D) that are associated with antibiotic resistance genes. Although antibiotic-resistant E. coli is commonly detected in municipal wastewater, little is known about the relationship between the phylogenetic groups and antibiotic-resistant E. coli in wastewater. In this study, the survival of E. coli in wastewater and the changes to the relationships between each phylogroup and the antibiotic-resistant profiles of E. coli isolates from wastewater were investigated under aerobic conditions for 14 days. The isolates were classified into the phylogroups A, B1, B2, and D or others by multiplex PCR. In addition, the susceptibility of the isolates to 11 antibiotics was assessed with the minimum inhibitory concentration (MIC) assay. While E. coli counts decreased in the wastewater with time under aerobic conditions, the prevalence of phylogroup B2 had increased to 73% on day 14. Furthermore, the MIC assay revealed that the abundance of antibiotic-resistant E. coli also increased on day 14. After batch-mixing the experiments under aerobic conditions, the surviving antibiotic-resistant E. coli included mainly multidrug-resistant and beta-lactamase-producing isolates belonging to phylogroup B2. These results suggest that the phylogroup B2 isolates that have acquired antibiotic resistance had a high survivability in the treated wastewater.

Information on the actual existence of antibiotic-resistant bacteria in rivers where sewage, urban wastewater, and livestock wastewater do not load is essential to prevent the spread of antibiotic-resistant bacteria in water environments. This study compared the antibiotic resistance profile of Escherichia coli upstream and downstream of human habitation. The survey was conducted in the summer, winter, and spring seasons. Resistance to one or more antibiotics at upstream and downstream sites was on average 18% and 20%, respectively, and no significant difference was observed between the survey sites. The resistance rates at the upstream site (total of 98 isolated strains) to each antibiotic were cefazolin 17%, tetracycline 12%, and ampicillin 8%, in descending order. Conversely, for the downstream site (total of 89 isolated strains), the rates were ampicillin 16%, cefazolin 16%, and tetracycline 1% in descending order. The resistance rate of tetracycline in the downstream site was significantly lower than that of the upstream site. Furthermore, phylogenetic analysis revealed that many strains showed different resistance profiles even in the same cluster of the Pulsed-Field Gel Electrophoresis (PFGE) pattern. Moreover, the resistance profiles differed in the same cluster of the upstream and the downstream sites. In flowing from the upstream to the downstream site, it is plausible that E. coli transmitted or lacked the antibiotic resistance gene.

Aspirin (acetylsalicylic acid) is a well-known nonsteroidal anti-inflammatory drug (NSAID) that has long been used as an anti-pyretic and analgesic drug. Recently, much attention has been paid to the chemopreventive and apoptosis-inducing effects of NSAIDs in cancer cells. These effects have been thought to be primarily attributed to the inhibition of cyclooxygenase activity and prostaglandin synthesis. However, recent studies have demonstrated unequivocally that certain NSAIDs, including aspirin and its metabolite salicylic acid, exert their anti-inflammatory and chemopreventive effects independently of cyclooxygenase activity and prostaglandin synthesis inhibition. It is becoming increasingly evident that two potential common targets of NSAIDs are mitochondria and the Ca2+ signaling pathway. In this review, we provide an overview of the current knowledge regarding the roles of mitochondria and Ca2+ in the apoptosis-inducing effects as well as some side effects of aspirin, salicylates and other NSAIDs, and introducing the emerging role of L-type Ca2+ channels, a new Ca2+ entry pathway in non-excitable cells that is up-regulated in human cancer cells.

Abstract.: Aspirin (acetylsalicylic acid) is a well-known nonsteroidal anti-inflammatory drug that can potentiate some acute allergies and causes adverse immunological reactions collectively referred to as aspirin intolerance, a disorder that induces urticaria, asthma, and anaphylaxis in response to oral administration of the drug. Aspirin also potentiates some acute allergies such as food-dependent exercise-induced anaphylaxis (FDEIA), a food allergy induced by physical exercise. The anti-inflammatory actions as well as the adverse immunological effects have been thought to be primarily due to inhibition of cyclooxygenase activity. However, a growing body of evidence suggests that mechanisms unrelated to inhibition of prostaglandin synthesis are involved. One key feature of aspirin intolerance is the overproductions of cysteinyl leukotrienes (LTs), in which mast cells have been implicated to play a role. In this review, we provide an overview of our current knowledge about the regulatory mechanisms of LTC4 secretion in mast cells and its modulation by aspirin, with a special emphasis on the role of Ca2+ signals. We also introduced our recent findings that mast cells express dihydropyridine-sensitive L-type Ca2+ channels (LTCCs) and that Ca2+ channels of this kind mediate aspirin modulation of LTC4 secretion in mast cells. Keywords:: mast cell, aspirin, L-type Ca2+ channel, leukotriene, allergic inflammation

We previously discovered that squalene monohydroperoxide (SQ-OOH) was produced on human forehead skin and suggested that skin squalene (SQ) may be the principal target lipid for oxidative stress (e.g., sunlight exposure). Because of its six double bonds, SQ peroxidation can yield various positional hydroperoxide isomers. However, the structural characterization of skin SQ-OOH isomers has never been reported. Here, we prepared pure SQ-OOH isomers and developed an analytical method for SQ-OOH isomers using a quadrupole/linear ion-trap mass spectrometer (QTRAP) MS/MS system. Collision-induced dissociation produced specific fragment ions for each SQ-OOH isomer, which permitted discrimination between SQ-OOH isomers by multiple reaction monitoring (MRM). When lipid extract from human forehead skin was subjected to LC-MS/MS with MRM, individual SQ-OOH isomers could be separated and detected with a sensitivity of 0.05 ng/injection. The total concentration of SQ-OOH isomers in forehead skin was ∼956 μg/g skin lipids, but it increased up to 2,760 μg/g skin lipids after 3 h of sunlight exposure. The LC-MS/MS method was useful for investigating the peroxidation mechanisms of SQ as well as SQ-OOH-mediated skin disorders.

It is well known that saintpaulia leaf is damaged by the rapid temperature decrease when cold water is irrigated onto the leaf surface. We investigated this temperature sensitivity and the mechanisms of leaf damage in saintpaulia (Saintpaulia sp. cv. 'Iceberg') and other Gesneriaceae plants. Saintpaulia leaves were damaged and discolored when subjected to a rapid decrease in temperature, but not when the temperature was decreased gradually. Sensitivity to rapid temperature decrease increased within 10 to 20 min during pre-incubation at higher temperature. Injury was restricted to the palisade mesophyll cells, where there was an obvious change in the color of the chloroplasts. During a rapid temperature decrease, chlorophyll fluorescence monitored by a pulse amplitude modulated fluorometer diminished and did not recover even after rewarming to the initial temperature. Isolated chloroplasts were not directly affected by the rapid temperature decrease. Intracellular pH was monitored with a pH-dependent fluorescent dye. In palisade mesophyll cells damaged by rapid temperature decrease, the cytosolic pH decreased and the vacuolar membrane collapsed soon after a temperature decrease. In isolated chloroplasts, chlorophyll fluorescence declined when the pH of the medium was lowered. These results suggest that a rapid temperature decrease directly or indirectly affects the vacuolar membrane, resulting in a pH change in the cytosol that subsequently affects the chloroplasts in palisade mesophyll cells. We further confirmed that the same physiological damage occurs in other Gesneriaceae plants. These results strongly suggested that the vacuoles of palisade mesophyll cells collapsed during the initial phase of leaf injury.