Decreased serum concentrations of nitric oxide metabolites among Chinese in an endemic area of chronic arsenic poisoning in inner Mongolia

Prolonged exposure to arsenic results in peripheral and cardiovascular manifestations, as does impaired production of endothelial nitric oxide (NO). In vitro studies have indicated that endothelial cells undergo damage by arsenic. However, no information has been available on the relationship between NO synthesis and chronic arsenic poisoning in humans. The present study was designed to reveal this question. The subjects were 33 habitants who continued to drink well water containing high concentrations of inorganic arsenic (mean value = 0.41 microg/ml) for about 18 years in Inner Mongolia, China, and 10 other people who lived in this area but exposed to minimal concentrations of arsenic (mean value = 0.02 microg/ml) were employed as controls. Mean blood concentration of total arsenic was six times higher in exposed subjects than controls; 42.1 vs. 7.3 ng/ml, p <.001. Mean serum concentration of nitrite/nitrate, stable metabolites of endogenous NO, was lower in arsenic-exposed subjects than in controls: 24.7 vs. 51.6 microM, p<.001. In total samples, an inverse correlation with serum nitrite/nitrate levels was strong for blood inorganic arsenic (r = -0.52, p <.001) and less strong for its metabolites, monomethyl arsenic (r = -0.45, p<.005) and dimethyl arsenic (r = -0.37, p<.05). Furthermore, serum nitrite/nitrate concentration was significantly correlated with nonprotein sulfhydryl level in whole blood (r = 0.58, p<.001). In an in vitro study, we demonstrated that inorganic arsenite or arsenate suppresses the activity of endothelial NO synthase in human umbilical vein endothelial cells. These results suggest that long-term exposure to arsenic by drinking well water possibly reduces NO production in endothelial cells, resulting in a decrease in reduced nitrite/nitrate concentrations. Peripheral vascular disorders caused by arsenic may be attributable in part to impairment of NO production in vivo.     

Fatty acid amide hydrolase substrate specificity

Fatty acid amide hydrolase (FAAH), also referred to as oleamide hydrolase and anandamide amidohydrolase, is a serine hydrolase responsible for the degradation of endogenous oleamide and anandamide, fatty acid amides that function as chemical messengers. FAAH hydrolyzes a range of fatty acid amides, and the present study examines the relative rates of hydrolysis of a variety of natural and unnatural fatty acid primary amide substrates using pure recombinant rat FAAH.     

Qualitative variation in roadside weed vegetation along an urban–rural road gradient

Information on mechanisms of differentiation or homogenization of urban floras is deficient, despite their importance for urban nature conservation and urban land management. Roads, as a major human promoter of urbanization, can be an initial habitat for plants dispersed by transportations. We assumed that variation in weed vegetation along urban–rural roadside gradients is small, particularly in curbside cracks. We classified vegetation occurring in curbside cracks along the National Route 3 in southern Japan and compared the characteristics of the vegetation types recognized. Species in curbside cracks were recorded on 40 plots. Three vegetation types were classified, in part related to surrounding land-use types. Although the Shannon–Wiener diversity index and the number of native species clearly differed among the vegetation types in the curbside cracks, no significant differences between the three floristic vegetation types were found in the number of non-natives and invasive alien species. This may result from the small specificity and complexity of landscape structures, due to the continuity and connectivity of paved-road networks. Of the 122 species, 44 were non-natives or invasive alien species. The vegetation types generally involved the same plant families, with large numbers of species from the Asteraceae and Poaceae, regardless of vegetation types, but frequency of occurrence of the two families clearly differed between natives and non-natives and invasive alien species. Ephemeral non-natives and invasive alien species, particularly Asteraceae and Poaceae, seem to have advantageous dispersal strategies or low habitat dependency facilitating their occurrence in curbside cracks, regardless of adjacent land uses and the urban–rural landscape gradient. Expansion of these species may cause a homogenization of regional floras along roads.     

Porphyromonas gingivalis lipopolysaccharide induces miR-146a without altering the production of inflammatory cytokines

Lipopolysaccharide (LPS) from Porphyromonas gingivalis, an oral Gram-negative bacterium, acts as a virulence factor for periodontal disease. Although P. gingivalis LPS does not induce proinflammatory cytokines as strongly as Escherichia coli LPS, it is still able to exploit negative Toll-like receptor (TLR) regulatory pathways and facilitate pathogen persistence. Recent reports suggest that microRNAs (miRNAs) are also involved in the regulation of TLR signaling. Here, we demonstrate that P. gingivalis LPS strongly induces miRNA-146a expression in THP-1 cells and THP-1-derived macrophages. However, the inhibition or overexpression of miR-146a, through the transfection of a specific inhibitor or precursor, respectively, had little effect on cytokine production in macrophages stimulated with P. gingivalis LPS. Moreover, the expression of interleukin-1 associated-kinase-1 (IRAK-1) and tumor-necrosis factor (TNF) receptor-associated factor-6 (TRAF6), potential target molecules of miR-146a, were not affected by the stimulation with P. gingivalis LPS. Because TLR signaling induces various negative regulators, these results call into question the role of miR-146a in cells stimulated with TLR ligands.     

Dysregulation of suppressor of cytokine signaling 3 in keratinocytes causes skin inflammation mediated by interleukin-20 receptor-related cytokines

Homeostatic regulation of epidermal keratinocytes is controlled by the local cytokine milieu. However, a role for suppressor of cytokine signaling (SOCS), a negative feedback regulator of cytokine networks, in skin homeostasis remains unclear. Keratinocyte specific deletion of Socs3 (Socs3 cKO) caused severe skin inflammation with hyper-production of IgE, epidermal hyperplasia, and S100A8/9 expression, although Socs1 deletion caused no inflammation. The inflamed skin showed constitutive STAT3 activation and up-regulation of IL-6 and IL-20 receptor (IL-20R) related cytokines, IL-19, IL-20 and IL-24. Disease development was rescued by deletion of the Il6 gene, but not by the deletion of Il23, Il4r, or Rag1 genes. The expression of IL-6 in Socs3 cKO keratinocytes increased expression of IL-20R-related cytokines that further facilitated STAT3 hyperactivation, epidermal hyperplasia and neutrophilia. These results demonstrate that skin homeostasis is strictly regulated by the IL-6-STAT3-SOCS3 axis. Moreover, the SOCS3-mediated negative feedback loop in keratinocytes has a critical mechanistic role in the prevention of skin inflammation caused by hyperactivation of STAT3.     

The COP9/signalosome increases the efficiency of von Hippel-Lindau protein ubiquitin ligase-mediated hypoxia-inducible factor-alpha ubiquitination

Oxygen-dependent ubiquitination of the alpha-subunit of hypoxia-inducible factor (HIF-alpha) by the (von Hippel-Lindau protein)-Elongin B/C-Cullin2-Rbx1 (VBC-Cul2) ubiquitin ligase, a member of the cullin-RING ubiquitin ligases (CRLs), plays a central role in controlling oxygen metabolism. Nedd8 conjugation of cullins enhances the ligase activity of CRLs, and the COP9/signalosome (CSN) enhances the degradation of several CRL substrates, although it removes Nedd8 from cullins. Here we demonstrate that CSN increased the efficiency of the VBC-Cul2 complex for recognizing and ubiquitinating substrates by facilitating the dissociation of ubiquitinated substrates from the pVHL subunit of the complex. Moreover CSN enhanced HIF-1alpha degradation by promoting the dissociation of HIF-1alpha from pVHL in cells. The length of the polyubiquitin chain conjugated to the substrate appeared to be involved in CSN-mediated dissociation of the substrate from pVHL. In contrast to other mechanisms underlying CSN-mediated activation of CRLs, the dissociation of ubiquitinated substrates from pVHL did not require the deneddylation activity of CSN, implying that CSN enhances degradation of CRL substrates by multiple mechanisms.     

Oversulfated chondroitin sulfate-E binds to BMP-4 and enhances osteoblast differentiation

Small leucine-rich proteoglycans, such as biglycan, and their side chain sulfated glycosaminoglycans (GAGs), have been suggested to be involved in bone formation and mineralization processes. The present study was designed to investigate whether chondroitin sulfate (CS), one of the GAG, and its oversulfated structures coupled with bone morphogenetic protein-4 (BMP-4) alter the differentiation and subsequent mineralization of MC3T3-E1 osteoblastic cells. CS-E, one of the oversulfated CS structure, enhanced cell growth, alkaline phosphatase (ALP) activity, collagen deposition, and mineralization whereas heparin enhanced only ALP activity and mineralization. As well as CS-E, CS-H, and CPS also enhanced the mineralization of the cells. CS-E enhanced the mineralization of the cells by interacting with protein in the conditioned medium. CS-E induced mineralization was significantly inhibited by an antibody against BMP-4. The addition of exogenous BMP-4 further increased the capacity of CS-E to enhance mineralization. Fluorescence correlation spectroscopy method using fluoresceinamine-labeled GAG revealed that the oversulfated GAGs have a high affinity for BMP-4. The disaccharide analysis of the cells indicated that MC3T3-E1 cells are capable of producing oversulfated structures of CS by themselves. The lack of CS from the cells after chondroitinase treatment resulted in the inhibition of mineralization. These results in the present study indicate that oversulfated CS, which possesses 4,6-disulfates in N-acetyl-galactosamine, binds to BMP-4 and promotes osteoblast differentiation and subsequent mineralization.     

Cytoplasmic and serum galectin-3 in diagnosis of thyroid malignancies

In order to address whether galectin-3 in the sera and fine needle aspirates serve as a diagnostic marker distinguishing between benign and malignant thyroid nodules, we developed an enzyme-linked immunosorbent assay. We quantified galectin-3 in fine needle aspirates from a series of 118 patients with thyroid nodules and serum galectin-3 from another series of 46 patients, which were compared with final histology after thyroidectomy. Relative galectin-3 value (ng/mg), defined as galectin-3 concentration (ng/ml) divided by total protein concentration (mg/ml) in fine needle aspirates, was significantly higher in papillary carcinoma than in the other thyroid entities. There was no significant difference in serum galectin-3 level among patients with thyroid nodules and healthy individuals. Accordingly, relative galectin-3 value allows a definitive diagnosis of papillary carcinoma independent of cellular morphology, whereas serum galectin-3 does not serve as a marker for papillary carcinoma.     

Spectroscopic study of the interaction between poly-(9-vinyladenine) and single or multistrand RNA.

The interaction between poly(9-vinyladenine) (PVAd) and poly[r(U)] was investigated by means of uv, CD, 1H-, and 31P-nmr spectroscopies. The interaction was dependent on the molecular weight of PVAd determined by uv and CD spectroscopies. Based on imino proton nmr, it was clearly found that PVAd formed the complex with poly[r(U)] by complementary hydrogen bonding. The interaction of PVAd with double- and triple-stranded helices of RNA was also investigated by uv melting behavior and 31P-nmr spectroscopy. The results suggested that PVAd could not interact with the double-stranded poly[r(A)].poly[r(U)] but did with the triple-stranded RNA.