Abnormal phosphorylation / dephosphorylation and Ca2+ dysfunction in heart failure.

Heart failure (HF) can be caused by a variety of causes characterized by abnormal myocardial systole and diastole. Ca2+ current through the L-type calcium channel (LTCC) on the membrane is the initial trigger signal for a cardiac cycle. Declined systole and diastole in HF are associated with dysfunction of myocardial Ca2+ function. This disorder can be correlated with unbalanced levels of phosphorylation / dephosphorylation of LTCC, endoplasmic reticulum (ER), and myofilament. Kinase and phosphatase activity changes along with HF progress, resulting in phased changes in the degree of phosphorylation / dephosphorylation. It is important to realize the phosphorylation / dephosphorylation differences between a normal and a failing heart. This review focuses on phosphorylation / dephosphorylation changes in the progression of HF and summarizes the effects of phosphorylation / dephosphorylation of LTCC, ER function, and myofilament function in normal conditions and HF based on previous experiments and clinical research. Also, we summarize current therapeutic methods based on abnormal phosphorylation / dephosphorylation and clarify potential therapeutic directions.

Generation of Elliptically Polarized Terahertz Waves from Antiferromagnetic Sandwiched Structure.

The generation of elliptically polarized electromagnetic wave of an antiferromagnetic (AF)/dielectric sandwiched structure in the terahertz range is studied. The frequency and external magnetic field can change the AF optical response, resulting in the generation of elliptical polarization. An especially useful geometry with high levels of the generation of elliptical polarization is found in the case where an incident electromagnetic wave perpendicularly illuminates the sandwiched structure, the AF anisotropy axis is vertical to the wave-vector and the external magnetic field is pointed along the wave-vector. In numerical calculations, the AF layer is FeF2 and the dielectric layers are ZnF2. Although the effect originates from the AF layer, it can be also influenced by the sandwiched structure. We found that the ZnF2/FeF2/ZnF2 structure possesses optimal rotation of the principal axis and ellipticity, which can reach up to about thrice that of a single FeF2 layer.

Saturated fatty acid induces insulin resistance partially through nucleotide-binding oligomerization domain 1 signaling pathway in adipocytes.

OBJECTIVE: To investigate the potential role of nucleotide-binding oligomerization domain 1 (NOD1), a component of the innate immune system, in mediating lipid-induced insulin resistance in adipocytes. METHODS: Adipocytes from Toll-like receptor 4 deficiency mice were used for stimulation experiments. The effect of oleate/palmitate mixture on nuclear factor-κB (NF-κB) activation was analyzed by reporter plasmid assay. The release of proinflammatory chemokine/cytokines production was determined by using real-time PCR. Insulin-stimulated glucose uptake was measured by 2-deoxy-D-[3H] glucose uptake assay. Chemokine/cytokine expression and glucose uptake in adipocytes transfected with small interfering RNA (siRNA) targeting NOD1 upon fatty acids treatment were analyzed. RESULTS: Oleate/palmitate mixture activated the NF-κB pathway and induced interleukin-6, tumor necrosis factor-α, and monocyte chemoattractant protein-1 mRNA expressions in adipocytes from mice deficient in Toll-like receptor 4, and these effects were blocked by siRNA targeting NOD1. Furthermore, saturated fatty acids decreased the ability of insulin-stimulated glucose uptake. Importantly, siRNA targeting NOD1 partially reversed saturated fatty acid-induced suppression of insulin-induced glucose uptake. CONCLUSION: NOD1 might play an important role in saturated fatty acid-induced insulin resistance in adipocytes, suggesting a mechanism by which reduced NOD1 activity confers beneficial effects on insulin action.

Role of sclerostin in the bone loss of postmenopausal chinese women with type 2 diabetes.

OBJECTIVE: To evaluate the role of sclerostin in bone loss of postmenopausal Chinese women with type 2 diabetes mellitus. METHODS: The postmenopausal patients suffering from type 2 diabetes mellitus and age, body mass index, and duration of menopause matched healthy controls were enrolled into this cross-sectional study according to criteria of inclusion and exclusion. The serum sclerostin level and bone mineral density of the anterior-posterior lumbar spine (L1-L4), femoral neck, and total hip were determined by using a quantitative sandwich ELISA kit and dual X-ray absorptiometry, respectively. Meanwhile, the clinical and laboratory indexes of bone mineral metabolism were analyzed. Associations between serum sclerostin level and bone mineral density as well as bone turnover markers were evaluated by linear regression analysis. RESULTS: Finally, 265 postmenopausal women with type 2 diabetes and 225 non-diabetic women were recruited in the diabetic group and control group, respectively. Serum sclerostin level of the diabetic group was significantly higher than that of the control group (48.2±19.4 vs. 37.2±18.6 pmol/L, P<0.001) and was increased with age in both groups (diabetic group, r=0.374, P<0.001; control group, r=0.312, P<0.001). In type 2 diabetes patients, serum sclerostin concentration was positively correlated with hemoglobin A1c level (r=0.237; P=0.021). Biochemical bone turnover markers, intact parathyroid hormone and bone-specific alkaline phosphatase, were negatively associated with serum sclerostin level (r=-0.138, P=0.078 and r=-0.265, P<0.001). Conversely, the positive correlation between sclerostin and C-terminal cross-linking telopeptide of type I collagen was found in diabetic patients (r=0.354, P<0.001). Serum sclerostin levels of the diabetic group were positively correlated with bone mineral density of the lumbar spine, femoral neck, and total hip (r=0.324, 0.367, and 0.416, respectively; all P<0.001). CONCLUSIONS: Sclerostin might participate in the pathogenesis of bone loss of type 2 diabetes. The high sclerostin level might serve as a marker of increased osteocyte activity in postmenopausal patients with type 2 diabetes mellitus.

Linoleic acid activates GPR40/FFA1 and phospholipase C to increase [Ca2+]i release and insulin secretion in islet beta-cells.

OBJECTIVE: To elucidate GPR40/FFA1 and its downstream signaling pathways in regulating insulin secretion. METHODS: GPR40/FFA1 expression was detected by immunofluorescence imaging. We employed linoleic acid (LA), a free fatty acid that has a high affinity to the rat GPR40, and examined its effect on cytosolic free calcium concentration ([Ca2+]i) in primary rat beta-cells by Fluo-3 intensity under confocal microscopy recording. Downregulation of GPR40/FFA1 expression by antisense oligonucleotides was performed in pancreatic beta-cells, and insulin secretion was assessed by enzyme-linked immunosorbent assay. RESULTS: LA acutely stimulated insulin secretion from primary cultured rat pancreatic islets. LA induced significant increase of [Ca2+]i in the presence of 5.6 mmol/L and 11.1 mmol/L glucose, which was reflected by increased Fluo-3 intensity under confocal microscopy recording. LA-stimulated increase in [Ca2+]i and insulin secretion were blocked by inhibition of GPR40/FFA1 expression in beta-cells after GPR40/FFA1-specific antisense treatment. In addition, the inhibition of phospholipase C (PLC) activity by U73122, PLC inhibitor, also markedly inhibited the LA-induced [Ca2+]i increase. CONCLUSION: LA activates GPR40/FFA1 and PLC to stimulate Ca2+ release, resulting in an increase in [Ca2+]i and insulin secretion in rat islet beta-cells.

Metabolomics of Fuzi-Gancao in CCl4 induced acute liver injury and its regulatory effect on bile acid profile in rats.

BACKGROUND: Fuzi (Radix aconiti lateralis)-Gancao (Radix glycyrrhizae) is one of the most classical drug pairs of traditional Chinese medicine. In clinical practice, decoctions containing Fuzi-Gancao (F-G) are often used in the treatment of liver diseases such as hepatitis and liver failure. AIM: To investigate the metabolomics of F-G in CCl4 induced acute liver injury in rats and its regulatory effect on the bile acid profile. METHODS: The pharmacodynamic effect of F-G on CCl4 induced acute liver injury in rats was evaluated, and an ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for the simultaneous determination of 92 metabolites from multiple pathways was established to explore the protective metabolic mechanism of F-G in serum on the liver. RESULTS: Twenty-four differential metabolites were identified in serum samples. The primary bile acid biosynthetic metabolic pathway was the major common pathway in the model group and F-G group. Subsequently, a UPLC-MS/MS method for simultaneous determination of 11 bile acids, including cholic acid, ursodeoxycholic acid, glycochenodeoxycholic acid, glycochenodeoxycholic acid, taurocholic acid, glycocholic acid, chenodeoxycholic acid, deoxycholic acid, taurochenodeoxycholic acid, taurocholic acid, and glycinic acid, was established to analyze the regulatory mechanism of F-G in serum. F-G decreased the contents of these 11 bile acids in serum in a dose-dependent manner compared with those in the model control group. CONCLUSION: F-G could protect hepatocytes by promoting the binding of free bile acids to glycine and taurine, and reducing the accumulation of free bile acids in the liver. F-G could also regulate the compensatory degree of taurine, decreasing the content of taurine-conjugated bile acids to protect hepatocytes.

Increased NOD1, but not NOD2, activity in subcutaneous adipose tissue from patients with metabolic syndrome.

OBJECTIVE: Nucleotide-binding oligomerization domain (NOD) protein, as cytoplasmic receptor of the innate immune response, plays an important role in adipose inflammation and insulin resistance in obesity. Our objective was to examine adipose tissue (AT) NOD in nascent metabolic syndrome (MetS) patients and to investigate its association with MetS features. METHODS: Thirty-four MetS subjects and 31 controls were recruited. Fasting blood was collected, and abdominal subcutaneous AT was obtained by biopsy for NOD1/NOD2 expression and activity. RESULTS: MetS subjects showed significantly increased expression for NOD1 on adipose depots as compared to controls. In addition to increased expression of downstream signaling mediators RIPK2 and NF-κB p65 nuclear translocation, there was remarkably higher release of monocyte chemotactic protein1 (MCP-1), interleukin (IL)-6, and IL-8 in MetS versus controls following priming of the isolated adipocytes with NOD1 ligand iE-DAP. With regard to NOD2, the differences between the two groups were not significant in either basal state or after activation. Increased NOD1 positively correlated with waist circumference. NOD1 was also correlated with HbA1c and HOMA-IR. NOD1 positively correlated with serum levels of IL-6, MCP-1, and NF-κB activity. CONCLUSIONS: Activation of the innate immune pathway via NOD1 may be partially responsible for the increased systemic inflammation and insulin resistance in MetS.

[Rapid biochemical method for the detection of paralytical shellfish poisoning toxins in shellfish from seafood market].

A rapid biochemical method was discussed in order to detect low concentration of paralytic shellfish poisoning (PSP) in sea food. The mice were injected with PSP extract of bivalves (1 and 0.2 microg/kg respectively, as STX equivalents) purchased from seafood market. ACh, AChE, NO and NOS in blood were studied at 15, 60, 120 min respectively. The results showed that at low dose (0.2 microg/kg) and 15 min, only the contents of ACh changed significantly compared with control group (p < 0.05), which was (141.2 +/- 14.8) microg/mg, while the contents of NO and the activities of NOS changed until 120 min, compared to control group (p < 0.05) ,which were (68.7 +/- 3.8) micromol/g and (40.1 +/- 4.9) U/mg respectively. At high dose the contents of ACh changed at all three time point. It can be suggested that the contents of ACh is the only one of four indexes which can response to PSP at low dose in an early stage (15 min) and may be selected as a biochemical index for rapid detection of PSP.

XpsG, the major pseudopilin in Xanthomonas campestris pv. campestris, forms a pilus-like structure between cytoplasmic and outer membranes.

GspG, -H, -I, -J and -K proteins are members of the pseudopilin family. They are the components required for the type II secretion pathway, which translocates proteins across the outer membrane of Gram-negative bacteria to the extracellular milieu. They were predicted to form a pilus-like structure, and this has been shown for PulG of Klebsiella oxytoca by using electron microscopy. In the present study, we performed biochemical analyses of the XpsG protein of Xanthomonas campestris pv. campestris and observed that it is a pillar-like structure spanning the cytoplasmic and outer membranes. Subcellular fractionation revealed a soluble form (SF) of XpsG, in addition to the membrane form. Chromatographic analysis of SF XpsG in the absence of a detergent indicated that it is part of a large complex (>440 kDa). In vitro studies indicated that XpsG is prone to aggregate in the absence of a detergent. We isolated and characterized a non-functional mutant defective in forming the large complex. It did not interfere with the function of wild-type XpsG and was not detectable in the SF. Moreover, unlike wild-type XpsG, which was distributed in both the cytoplasmic and outer membranes, it appeared only in the cytoplasmic membrane. When wild-type XpsG was co-expressed with His6-tagged XpsH but not with untagged XpsH, SF XpsG bound to nickel and co-eluted with XpsH. This result suggests the presence of other pseudopilin components in the XpsG-containing large-sized molecules.