Saccharomyces cerevisiae- and Candida albicans-derived mannan induced production of tumor necrosis factor alpha by human monocytes in a CD14- and Toll-like receptor 4-dependent manner

The cytokine-inducing activities of fungal polysaccharides were examined in human monocytes in culture, with special reference to CD14 and Toll-like receptors (TLRs). Tumor necrosis factor alpha (TNF-alpha) production by monocytes was markedly induced in a dose-dependent manner upon stimulation with cell walls from Candida albicans and mannan from Saccharomyces cerevisiae and C. albicans, although relatively high concentrations (10 to 100 microg/ml) of stimulants were required for activation as compared with the reference lipopolysaccharide (LPS) (1 to 10 ng/ml). The yeast form C. albicans and its mannan and cell wall fractions exhibited higher TNF-alpha production than respective preparations from the hyphal form. Only slight TNF-alpha production was induced by the S. cerevisiae glucan. The TNF-alpha production triggered by reference LPS and purified fungal mannans required the presence of LPS-binding protein (LBP), and these responses were inhibited by anti-CD14 and anti-TLR4 antibodies, but not by anti-TLR2 antibody. In contrast to the activity of LPS, the activity of purified S. cerevisiae mannan was not inhibited by polymyxin B. These findings suggested that the mannan-LBP complex is recognized by CD14 on monocytes and that signaling through TLR4 leads to the production of proinflammatory cytokines in a manner similar to that induced by LPS.     

Midkine expression is associated with postnatal development of the lungs

A heparin-binding growth factor, midkine, is the product of a retinoic acid-responsive gene. Since retinol plays critical roles in lung development and treatment of bronchopulmonary dysplasia, and midkine has been implicated in the maturation of lung explants and in cytoprotection, we herein examined midkine expression during postnatal development of the lungs and hyperoxic lung injury. Midkine protein transiently increased to a maximum level at around 4 days postnatal. Immunohistochemistry revealed that the amounts of midkine increased in resident alveolar cells, but not in smooth muscle cells or the large airway epithelium. If neonatal mice were exposed to >95% oxygen, lung development was impaired and midkine expression was suppressed. In contrast, when adult mouse lungs as well as in vitro cultured lung adenocarcinoma cells were exposed to hyperoxia, midkine expression was not affected. Furthermore, a pronounced induction of midkine by retinoic acid was observed in neonatal lungs. The results indicate that midkine expression is associated with postnatal lung development, but not necessarily with hyperoxic cell damage.     

Effects of phosphatidylcholine/phosphatidylethanolamine composition in cholesteryl ester-micellar substrates on neutral cholesterol esterase activity

The effect of phospholipid composition in cholesteryl ester (CE)-micellar substrates on neutral cholesterol esterase (N-CEase) activity was examined. N-CEase preparation was incubated with micelles composed of cholesteryl-[1-14C]-oleate, sodium taurocholate, and phosphatidylcholine (PC)/phosphatidylethanolamine (PE) at varying ratios (%PE:0 = PC only, 17, 33, 50, 66, 83). The activity increased dependently with the increase in PE content; the activity with the micelles containing the highest ratio of PE was 2.5-fold compared with the micelles consisting of PC only. Vmax with the micelles of 83, 66, and 50% PE was 3.1-, 2.7-, and 1.9-fold, respectively, compared with the micelles of PC only. Each micellar preparation was chromatographed through a Superose 6 column by the FPLC system. In 66 and 83% PE-containing micelles, PC, PE, CE, and part of sodium taurocholate eluted completely together in a single peak, whereas in micelles with 33 and 50% PE they eluted loosely together. The micelles with PC only or 17% PE formed PC-micelles without including CE and PE. It is concluded that PE plays a critical role in the formation of CE micelles with PC, and in the interaction with N-CEase. The CE-micelles with 66-83% PE serve as substrates for sensitive and reproducible N-CEase assay.     

Voltage-dependent outward K+ current in intermediate cell of stria vascularis of gerbil cochlea

A voltage-dependent outwardK⁺(K_V) current in the intermediatecell (melanocyte) of the cochlear stria vascularis was studied usingthe whole cell patch-clamp technique. TheK_V current had an activationthreshold voltage of approximately 80 mV, and 50% activationwas observed at 42.6 mV. The time courses of activation andinactivation were well fitted by two exponential functions: the timeconstants at 0 mV were 7.9 and 58.8 ms for activation and 0.6 and 4.3 sfor inactivation. The half-maximal activation time was 13.8 ms at 0 mV.Inactivation of the current was incomplete even after a prolongeddepolarization of 10 s. This current was independent of intracellularCa²⁺. Quinine, verapamil,Ba²⁺, and tetraethylammoniuminhibited the current in a dose-dependent manner, but 4-aminopyridinewas ineffective at 50 mM. We conclude that theK_V conductance in the intermediatecell may stabilize the membrane potential, which is thought to beclosely related to the endocochlear potential, and may provide anadditional route for K⁺ secretioninto the intercellular space.

     

Protective effect of Fucoxanthin against UVB-induced skin photoaging in hairless mice

Fucoxanthin, a major carotenoid in brown algae, has various beneficial effects. In this study, we evaluated the effect of topical fucoxanthin on UVB-induced skin photoaging in hairless mice. The dorsal skins were treated topically with a 0.001% fucoxanthin solution 2 h each time before UVB irradiation (5 times a week) for 10 weeks. The formation of wrinkles in UVB-irradiated skin treated with vehicle alone significantly increased, as compared with the non-irradiated control. Treatment with fucoxanthin tended to suppress UVB-induced wrinkle formation, but there was no significant difference between wrinkle formation in the control group and the fucoxanthin treatment group. However, topical treatment with fucoxanthin significantly lessened UVB-induced epidermal hypertrophy, VEGF, and MMP-13 expression in the epidermis and thiobarbituric acid reactive substances (TBARS) in the skin. These results indicate that topical treatment with fucoxanthin prevents skin photoaging in UVB-irradiated hairless mice, possibly via antioxidant and antiangiogenic effects.     

Maternal ageing and nondisjunction: A comparative study of two chromosomal techniques on the formation of univalents in first meiotic metaphase oocytes of the mouse

The incidence of univalents was compared between slides prepared according to two clearly different chromosomal methods, i.e. Tarkowski's method and ours, in order to examine whether a univalent pair could be formed artifactually at the first meiotic metaphase (MI). The oocytes used were obtained from young (2–3 months) and old (12–15 months) age groups of both C57BL/6 and dd mice. In Tarkowski's method only a single fixative was used, while in our method three different fixatives were used successively in order to fix oocytes without their being ruptured. Despiralized, fuzzy and loosely associated chromatids were seen frequently in the slides prepared by Tarkowski's method, while such features were seen less frequently in the slides prepared by our method. The incidence of oocytes with univalents in the slides made by Tarkowski's method was much higher than in those made by ours in both age and strain groups (P<0.05–0.001). Thus, it was confirmed that the so-called univalents could be produced artifactually. The results did not support the production line hypothesis of Henderson and Edwards (1968) which was based on their observation of an increased incidence of univalents in MI oocytes from aged female mice.     

The lung as a possible target organ for atrial natriuretic polypeptide secreted from the heart

Using a specific radioimmunoassay (RIA) for alpha-rat atrial natriuretic polypeptide (alpha-rANP), we have demonstrated the presence of a considerable amount (6.10 +/- 0.38 ng/g) (mean +/- SE) of alpha-rANP-like immunoreactivity (alpha-rANP-LI) in the rat lung, the first organ through which atrial natriuretic polypeptide (ANP) released from the heart passes. High performance gel permeation chromatography coupled with the RIA revealed that most of alpha-rANP-LI eluted at the position of a low molecular weight form corresponding to synthetic alpha-rANP. In 2- or 5-day water-deprived rats, the concentration and content of alpha-rANP-LI in the lung decreased significantly compared with those of control rats. In addition, water-deprivation induced a significant decrease in the plasma concentration of alpha-rANP-LI simultaneously determined. There was a significant positive correlation between the concentrations of alpha-rANP-LI in the lung and plasma (r = 0.591, P less than 0.01). These results indicate the presence of ANP in the lung and suggest physiological roles of ANP in pulmonary function.     

Hemagglutinating activity of vibrio cholerae enterotoxin

Abstract The hemagglutinating activity and carbohydrate specificity of cholera toxin (cholera enterotoxin) was studied using hemagglutination and hemagglutination inhibition. Hemagglutination was obtained with cholera toxin at >108 μg/ml for human types A, B, and O erythrocytes, >216 μg/ml for chicken erythrocytes, and >865 μg/ml for sheep erythrocytes. When the erythrocytes were treated with either neuraminidase or pronase, the hemagglutinating activity of cholera toxin was enhanced about 8- to 32-fold. Hemagglutination of pronase-treated human type B erythrocytes induced by cholera toxin was inhibited by lactose, galactose, melibiose and l -arabinose. Lactose was the most effective of the mono-, di-, and polysaccharides used as inhibitors, being a slightly better inhibitor than galactose, and much more potent than melibiose. These results suggest that cholera toxin is a bacterial lectin specific for galactose and/or lactose.