Properties of the electrogenic activity of bacteriorhodopsin

In this study, we analyzed the photoelectric current generated by bacteriorhodopsin adsorbed on a polymer film, “Lumirror” (Muneyuki et al. in FEBS Lett 427:109–114, 1998). We could examine the photoelectric current over a wide range of light intensity and pH values using the same membrane owing to the mechanical and chemical stability of the thin polymer film. We analyzed the photoelectric current by comparison with a simple equivalent electric circuit. Analysis of experimental results obtained at different light intensities suggested that the electromotive force of the bacteriorhodopsin was independent of light intensity. The pH dependence of the photoelectric current suggested that the bacteriorhodopsin could generate a maximum electromotive force at approximately pH 6.     

High-performance thin-layer chromatography/mass spectrometry for the analysis of neutral glycosphingolipids

This mini-review summarizes the protocol we have developed for the analysis of neutral glycosphingolipids (GSLs) by high-performance thin layer chromatography (HPTLC)-mass spectrometry (MS). We also present results obtained using this glycolipidomic approach to study neutral GSLs from mouse kidney, spleen, and small intestine. Finally, we discuss what is required for further development of this method, as well as what is expected for the future of glycolipid biology.     

Oxidized low-density lipoprotein-induced periodontal inflammation is associated with the up-regulation of cyclooxygenase-2 and microsomal prostaglandin synthase 1 in human gingival epithelial cells

Periodontitis is characterized by chronic gingival tissue inflammation, and inflammatory mediators such as IL-8 and prostaglandin E₂ (PGE₂) are associated with disease progression. Previously we showed that oxidatively modified low-density lipoprotein (oxLDL) was present in gingival crevicular fluid. In this study, the role of oxLDL in the gingival epithelial cell inflammatory response was further investigated using Ca9-22 cells and primary human oral keratinocytes (HOK). Treatment of Ca9-22 cells and HOK with oxLDL induced an up-regulation of IL-8 and the PGE₂-producing enzymes, cyclooxygenase-2 and microsomal PGE₂ synthase-1. These responses induced by oxLDL were significantly suppressed by a nuclear factor-kappa B (NF-κB) inhibitor. However, unlike the result in macrophages, oxLDL did not lead to an increase in CD36 expression in these two cells. These results suggest that oxLDL elicits gingival epithelial cell inflammatory responses through an activation of the NF-κB pathway. These data suggest a mechanistic link between periodontal disease and lipid metabolism-related disorders, including atherosclerosis.     

A spectroscopic variant of the light-harvesting 1 core complex from the thermophilic purple sulfur bacterium Thermochromatium tepidum

Thermochromatium tepidum is a purple sulfur photosynthetic bacterium, and its light-harvesting 1 reaction center (LH1RC) complexes exhibit an unusual LH1 Q(y) absorption at 915 nm (B915) and possess enhanced thermal stability. These unique properties are closely related to an inorganic cofactor, Ca(2+). Here, we report a spectroscopic variant of LH1RC complexes from Tch. tepidum cells in which Ca(2+) was biosynthetically replaced with Sr(2+). The photosynthetic growth of wild-type cells cannot be maintained without Ca(2+) and is heavily inhibited when the Ca(2+) is replaced with other metal cations. Interestingly, only Sr(2+) supported photosynthetic growth instead of Ca(2+) with slightly reduced rates. The resulting Sr-tepidum cells exhibited characteristic absorption spectra in the LH1 Q(y) region with different LH1RC:LH2 ratios depending on the growth conditions. LH1RC complexes purified from the Sr-tepidum cells exhibited a Q(y) maximum at 888 nm (B888) that was blue-shifted after removal of Sr(2+) to ～870 nm (B870). Reconstitution of Sr(2+) and Ca(2+) into B870 resulted in red shifts of the Q(y) peak to 888 and 908 nm, respectively. The thermal stability of B888 was slightly lower than that of B915 as revealed by differential scanning calorimetry analysis. Effects of other divalent metal cations on the Q(y) peak position and thermal stability of B888 were similar but not identical to those of B915. This study provides the first evidence of a purple bacterium in which LH1RC complexes alter spectroscopic and thermodynamic properties in vivo by utilizing exogenous metal cations and improve the ability to adapt to the environmental changes.     

Induction of dual-specificity phosphatase 1 (DUSP1) by pulsatile gonadotropin-releasing hormone stimulation: role for gonadotropin subunit expression in mouse pituitary LbetaT2 cells

The adherens junction (AJ) is important for maintaining uterine structural integrity, composition of the luminal environment, and initiation of implantation by virtue of its properties of cell-cell recognition, adhesion, and establishment of cell polarity and permeability barriers. In this study, we investigated the uterine changes of AJ components E-cadherin, beta-catenin, and alpha-catenin at their mRNA and protein levels, together with the cellular distribution of meprinbeta, phospho-beta-catenin, and active beta-catenin proteins, in hamsters that show only ovarian progesterone-dependent uterine receptivity and implantation. By in situ hybridization and immunofluorescence, we have demonstrated that uterine epithelial cells expressed three of these AJ proteins and their mRNAs prior to and during the initial phase of implantation. Immunofluorescence study showed no change in epithelial expression patterns of uterine AJ proteins from Days 1 to 5 of pregnancy. With advancement of the implantation process, AJ components were primarily expressed in cells of the secondary decidual zone (SDZ), but not in the primary decidual zone (PDZ). In contrast, we noted strong expression of beta-catenin and alpha-catenin proteins in the PDZ, but not in the SDZ, of mice. Taken together, these results suggest that AJ proteins contribute to uterine barrier functions by cell-cell adhesion to ensure protection of the embryo. In addition, cleavage of E-cadherin by meprinbeta might contribute to weakening uterine epithelial cell-cell contact for blastocyst implantation. We also report that the nuclear localization of active beta-catenin from Day 4 onward in hamsters implies that beta-catenin/Wnt-signal transduction is activated in the uterus during implantation and decidualization.     

A membrane filtering method for the purification of giant unilamellar vesicles

The use of giant unilamellar vesicles (GUVs) for investigating the properties of biomembranes is advantageous compared to the use of small-sized vesicles such as large unilamellar vesicles (LUVs). Experimental methods using GUVs, such as the single GUV method, would benefit if there was a methodology for obtaining a large population of similar-sized GUVs composed of oil-free membranes. We here describe a new membrane filtering method for purifying GUVs prepared by the natural swelling method and demonstrate that, following purification of GUVs composed of dioleoylphosphatidylglycerol (DOPG)/dioleoylphosphatidylcholine (DOPC) membranes suspended in a buffer, similar-sized GUVs with diameters of 10–30 μm are obtained. Moreover, this method enabled GUVs to be separated from water-soluble fluorescent probes and LUVs. These results suggest that the membrane filtering method can be applied to GUVs prepared by other methods to purify larger-sized GUVs from smaller GUVs, LUVs, and various water-soluble substances such as proteins and fluorescent probes. This method can also be used for concentration of dilute GUV suspensions.     

Physiological and psychological effects of walking on young males in urban parks in winter

Background

Interaction with nature has a relaxing effect on humans. Increasing attention has been focused on the therapeutic effects of urban green space; however, there is a lack of evidence-based field research. This study provided scientific evidence supporting the physiological and psychological effects of walking on young males in urban parks in winter.

Findings

Subjects (13 males aged 22.5 ± 3.1 years) were instructed to walk predetermined 15-minute courses in an urban park (test) and in the city area (control). Heart rate and heart rate variability (HRV) were measured to assess physiological responses. The semantic differential (SD) method, Profile of Mood States (POMS), and State-Trait Anxiety Inventory (STAI) were used to determine psychological responses.Heart rate was significantly lower and the natural logarithm of the high frequency component of HRV was significantly higher when walking through the urban park than through the city area. The results of three questionnaires indicated that walking in the urban park improved mood and decreased negative feelings and anxiety.

Conclusions

Physiological and psychological data from this field experiment provide important scientific evidence regarding the health benefits of walking in an urban park. The results support the premise that walking in an urban park has relaxing effects even in winter.     

Association between Myocardial Triglyceride Content and Cardiac Function in Healthy Subjects and Endurance Athletes

Ectopic fat accumulation plays important roles in various metabolic disorders and cardiovascular diseases. Recent studies reported that myocardial triglyceride (TG) content measured by proton magnetic resonance spectroscopy (¹H-MRS) is associated with aging, diabetes mellitus, and cardiac dysfunction. However, myocardial TG content in athletes has not yet been investigated. We performed ¹H-MRS and cardiac magnetic resonance imaging in 10 male endurance athletes and 15 healthy male controls. Serum markers and other clinical parameters including arterial stiffness were measured. Cardiopulmonary exercise testing was also performed. There were no significant differences in clinical characteristics including age, anthropometric parameters, blood test results, or arterial stiffness between the two groups. Peak oxygen uptakes, end–diastolic volume (EDV), end–systolic volume (ESV), left ventricular (LV) mass, peak ejection rates and peak filling rates were significantly higher in the athlete group than in the control group (all P<0.02). Myocardial TG content was significantly lower in the athlete group than in the control group (0.60±0.20 vs. 0.89±0.41%, P<0.05). Myocardial TG content was negatively correlated with EDV (r = −0.47), ESV (r = −0.64), LV mass (r = −0.44), and epicardial fat volume (r = 0.47) (all P<0.05). In conclusion, lower levels of myocardial TG content were observed in endurance athletes and were associated with morphological changes related to physiological LV alteration in athletes, suggesting that metabolic imaging for measurement of myocardial TG content by ¹H-MRS may be a useful technique for noninvasively assessing the “athlete’s heart”.