Polymorphisms rs763110 in FASL is linked to hepatitis C virus infection among high-risk populations.

BACKGROUND: The Fas cell surface death receptor (FAS) and Fas ligand (FASL) can participate in the apoptosis of immune cells and target cells infected with a virus through the FAS-FASL signalling pathway. The decoy receptor 3 (DCR3) can competitively inhibit the binding of FAS to FASL. Our aim is to investigate the effect of single nucleotide polymorphisms (SNPs) in FAS, FASL and DCR3 on hepatitis C virus (HCV) infection. METHODS: Four SNPs (rs763110 in FASL, rs1324551 and rs2234767 in FAS and rs2257440 in DCR3) were genotyped in 1495 controls free of HCV, 522 individuals with spontaneous HCV clearance and 732 patients with hepatitis C virus infection. The RegulomeDB database and RNAfold web servers were used to explore potential biological functions of SNPs. RESULTS: FASL rs763110 was associated with susceptibility to HCV infection, and not to CHC. The odds ratio (95% confidence interval) of HCV infection in high-risk populations carrying FASL rs763110-TT was 1.82 (1.36-2.51, P < 0.001) compared to that of CC genotypes and 1.93 (1.43-2.60, P < 0.001) higher than that of CC + CT genotypes. Based on computer simulation, FASL rs763110-T may affect the transcription of mRNA by affecting the binding of a transcription factor, leading to structural changes in mRNA. CONCLUSION: The genetic variant in FASL is linked with HCV infection, but not to spontaneous HCV clearance.

[Study on thyroid hormone levels and influence factors in drug users in a drug rehabilitation center in Jiangsu province].

Objective: To understand the serum levels of thyroid stimulating hormone (TSH), free triiodothyronine (FT3), free thyroxine (FT4), triiodothyronine (T3), and thyroxine (T4) and identify the related influencing factors of thyroid dysfunction in drug users. Methods: From June to August 2018, a face-to-face questionnaire survey was conducted in 788 male drug users in a drug rehabilitation center in Jiangsu province to collect their socio-demographic information. Then, venous blood sample was collected from each participant for the detection of various hematological indicators, such as thyroid hormones. Results: The abnormal rates of T3, T4, FT3, FT4 and TSH were 4.57%, 1.27%, 0.51%, 0.38% and 0.89%, respectively, in the male drug users. HCV infection was an influencing factor for abnormal T3 level in the male drug users (OR=8.52, 95%CI: 2.36-30.74, P=0.001). And serum T3 (P<0.001) and T4 (P=0.048) levels increased with increasing HCV viral load. Conclusions: HCV infection was an influencing factor for the abnormality of serum T3 level in drug users. Therefore, thyroid-related knowledge should be added in the health education for drug users, and the monitoring of thyroid function should be strengthened for drug users infected with HCV.

[Evaluating the efficacy of fractional exhaled nitric oxide and impulse oscillometry in screening out cough variant asthma from patients with subacute cough].

Objective: To evaluate the clinical value of fractional exhaled nitric oxide (FeNO) and impulse oscillometry (IOS) in screening out cough variant asthma (CVA) from patients with subacute cough. Methods: Patients with subacute cough were included from the outpatient department of Respiratory Medicine of Zhujiang Hospital of Southern Medical University from May to October in 2016. Based on "the guidelines for the diagnosis and treatment of cough (2015 edition)" , patients were classified into CVA group, and non CVP group with other causes of subacute cough. Lung function, bronchial provocation test, FeNO and IOS were measured. The diagnostic efficiency and optimal cut-off points of FeNO and IOS indicators to diagnose CVA from subacute cough were respectively assessed by the receiver operating characteristic (ROC) curves. Results: A total of 85 patients with subacute cough were included. Among them, 35 patients were diagnosed with CVA (CVA group), the others are classified as non CVP group (n=50). In CVA group, the levels of FeNO and total respiratory impedance (Zrs) were significantly higher, while maximal mid expiratory flow (MMEF)%pred, and mid expiratory flow (MEF)75/50/25%pred, reactance at 5 Hz (X5) levels were significantly lower than those in non CVP group (all P<0.05). Furthermore, the FeNO had a positive correlation with Zrs and Fres (ρ=0.312, P=0.003 and ρ=0.318, P=0.003, respectively), had a negative correlation with X5 (ρ=-0.288, P=0.007). A ROC analysis indicated that the area under ROC curve (AUC) of FeNO in diagnosis of CVA was 0.786 (95% CI: 0.684-0.889), the best cut-off point of FeNO volume ratio was 24.5×10(-9). When FeNO volume ratio=24.5×10(-9,) the sensitivity of in diagnosing CVA was 77.8%, specificity was 70.0%. The AUC for Zrs and X5 were 0.679 and 0.687, respectively. The combination of FeNO and X5 had a greater AUC than other indicators (AUC: 0.817, 95% CI: 0.726-0.908), the sensitivity and specificity were 80.6% and 66.0%, respectively. Conclusion: Both FeNO level and IOS index can be used to screen CVA in patients with subacute cough, and the combination of both have better value in diagnosing CVA.

Fluoroscopy-guided gastric peroral endoscopic pyloromyotomy (G-POEM): a more reliable and efficient method for treatment of refractory gastroparesis.

INTRODUCTION: Prior studies show promising results of the gastric peroral endoscopic pyloromyotomy (G-POEM) procedure for treatment of refractory gastroparesis. One major technical challenge involved in this procedure is identifying the pyloric muscular ring (PMR). The aim of this study is to establish a reliable method for identification of the PMR during G-POEM. METHODS: Fluoroscopy-guided G-POEM was performed by placing an endoclip at the 9 to 11'o clock position at the pylorus for identification of PMR. Conventional G-POEM was performed by observation of blue colored mucosa at the pylorus area as an indirect marker for PMR. The degree of the PMR identification was graded into well identified, identified, and not identified based on the appearance of the PMR. Procedure times were accurately documented. Gastroparesis cardinal symptoms index and gastric emptying scintigraphy were evaluated before and after the procedure. RESULTS: Fourteen patients were studied, seven underwent fluoroscopy-guided G-POEM, and seven patients underwent conventional G-POEM. All procedures achieved technical success and no adverse events occurred. In the seven patients who underwent fluoroscopy-guided G-POEM, the PMR was well identified in four patients and identified in three patients. In the seven patients who underwent conventional G-POEM, the PMR was identified in four patients and not identified in three patients. The average time to complete the fluoroscopy-guided G-POEM was significantly shorter than that of the conventional G-POEM. CONCLUSIONS: Fluoroscopy-guided G-POEM by placement of an endoclip at the pylorus was a reliable and safe method to direct the orientation of the submucosal tunnel, to facilitate the location of the PMR, and to shorten the procedure time.

Passive transfer of lipopolysaccharide-derived myeloid-derived suppressor cells inhibits asthma-related airway inflammation.

OBJECTIVE: Myeloid-derived suppressor cells (MDSCs) have recently been implicated in the pathogenesis of asthma through inhibiting T cell response. However, the issue of whether Lipopolysaccharide (LPS)-derived MDSCs regulate the immune response in an asthma environment is currently unclear. We sought to characterize the pathogenic function of various subtypes of MDSCs in asthma mediated by ovalbumin in mice model, in order to show that LPS-induced MDSCs can shift the balance back to normal in a Th2-dominant asthmatic environment. MATERIALS AND METHODS: Subgroups of MDSCs with Ly6C+Ly6G+, Ly6C-Ly6G+, Ly6C+Ly6G- or Ly6C-Ly6G- expression were isolated by flow cytometry and were co-cultured with spleen lymphocytes. The proportion of Th1, Th2, or Treg cells in the treated spleen lymphocytes were analyzed by flow cytometry. In an ovalbumin (OVA)-induced mouse asthma model, mice were intravenously injected (tail vein) by MDSCs with specific marker, then the lung function and tissue pathology, IL-4 content in bronchoalveolar lavage fluid (BALF) and peripheral blood, and proportion of Th1, Th2, or Treg cells in peripheral blood were analyzed. RESULTS: Ly6C+Ly6G+ MDSCs transferred into asthmatic mice via intravenous injection suppressed the infiltration of inflammatory cells into the lung and Th2 cytokine in BALF and blood. We observed a significant increase of Treg cells in the spleen lymphocytes co-cultured with Ly6C+Ly6G+, Ly6C-Ly6G+, Ly6C+Ly6G-, Ly6C-Ly6G- or CD11b+ MDSCs. The adoptive transfer of Ly6C+Ly6G+, Ly6C-Ly6G+, CD11b+ MDSCs resulted in decrease of Penh, total cell number, eosinophil and neutrophil percentage in BALF, and concentration of IL-4 in BALF and serum, thus improving the inflammatory injury, histopathology and lung function in the mice with asthma. The up-regulation of the Th1/Th2 ratio and Treg frequency were observed after adoptive transfer of Ly6C+Ly6G+, Ly6C-Ly6G+, Ly6C+Ly6G-, Ly6C-Ly6G- and CD11b+ MDSCs. CONCLUSIONS: The LPS-derived MDSCs with specific markers were able to suppress natural inflammatory response and improve inflammatory injury through reversing Th1/Th2 ratio, increasing Treg proportion and decreasing IL-4 concentration. These findings imply that LPS-derived MDSCs inhibit Th2 cell-medicated response against allergen. We propose that asthma may be effectively targeted using a novel MDSC-based cell therapy approach.

Role of cysteine residues in human plasma phospholipid transfer protein.

Phospholipid transfer protein (PLTP) belongs to a family of human plasma lipid transfer proteins that bind to small amphophilic molecules. PLTP contains cysteines at residues 5, 129, 168, and 318. Bactericidal/permeability-increasing protein, which is a member of the same gene family, contains an essential disulfide bond between Cys135 and Cys175; these residues, which correspond to Cys129 and Cys168 in PLTP, are conserved among all known members of the gene family. To identify the importance of these and the remaining cysteine residues to PLTP secretion and activity, each was replaced by a glycine by site-directed mutagenesis. The mutant as well as wild-type PLTP cDNAs were cloned into the mammalian expression vector pSV.SPORT1, and the PLTP cDNAs were transfected to COS-6 cells for expression. PLTP Cys129 --> Gly and PLTP Cys168 --> Gly were secretion incompetent. Neither PLTP mass nor activity was detectable in cell lysates and culture medium. Relative to wild-type PLTP, PLTP Cys5 --> Gly and PLTP Cys318 --> Gly exhibited similar specific activities but partially impaired PLTP synthesis and secretion. Intracellular PLTP appeared as two bands of 75 and 51 kDa corresponding to reported molecular masses for the glycosylated and nonglycosylated forms. The specific activities of PLTP Cys5 --> Gly and PLTP Cys318 --> Gly were similar in the cell lysates and medium, suggesting that glycosylation does not affect transfer activity.

Molecular basis of fish-eye disease in a patient from Spain. Characterization of a novel mutation in the LCAT gene and lipid analysis of the cornea.

The genetic and biochemical basis of fish-eye disease (FED) was investigated in a 63-year-old female proband with low plasma HDL cholesterol. Analyses of corneal and plasma lipids of the proband were consistent with impaired lecithin:cholesterol acyltransferase (LCAT) activity. Free cholesterol and phospholipid levels were elevated relative to control values, whereas cholesteryl ester levels were greatly reduced. Fatty acid compositions of corneal lipids from the proband and control subjects differ from the respective fatty acid compositions of their plasma lipids. This suggests that the metabolic pathways and acyl chain specificities for phospholipid, cholesteryl ester, and triglyceride metabolism within the cornea are distinct from those of plasma. Sequencing of the LCAT gene from the proband revealed a novel mutation at nucleotide 399, corresponding to an Arg99-->Cys substitution. Secretion of LCAT (Arg99-->Cys) by transfected COS-6 cells was approximately 50% of that of the wild type, but its specific activity against reassembled HDL was 93% lower than that of wild-type LCAT. The specific activities of wild-type and LCAT (Arg99-->Cys) against LDL were reduced similarly, suggesting that the appearance of the FED phenotype does not require enhanced activity against LDL. Our data support the hypothesis that FED is a partial LCAT deficiency in which poor esterification in specific types of HDL particles may contribute to the appearance of the corneal opacities.

[Interactions between ciprofloxacin, Mg2+, Mn2+ and DNA by electrochemical method].

Interactions between ciprofloxacin (CPFX), Mg2+, Mn2+ and DNA, and their polarographic and voltammetric behaviour were studied. In 0.1 mol.L-1 NH3-NH4Cl buffer solution (pH 9.2), a new reduction peak was obtained by linear-sweep voltammetry with Ep = -1.72 V(vs Ag/AgCl) when adding DNA to CPFX solution, which implies binding of CPFX with DNA. In the presence of Mg2+ or Mn2+, another new sensitive reduction peak, whose peak potential is more negative (Ep = -1.78 V), was obtained which suggested that Mg2+ or Mn2+ took part in the interaction between CPFX and DNA resulting in a ternary complex of CPFX-Mg-DNA. The peak current (ip) is proportional to the concentration of DNA over the range of 1.18 x 10(-4)-3.33 x 10(-4) mol.L-1. In this paper, the properties of the peak current were studied in detail, the result showed that the electrode reaction was irreversible and the ip was influenced by adsorption. The electrode reaction mechanism was also probed into. The CPFX molecule in the complex was reduced on the electrode. Furthermore, CPFX-Mg was shown ot be intercalated between the stacked base pairs of native DNA.

In vitro expression of natural mutants of human lecithin:cholesterol acyltransferase.

Fish-eye disease (FED) and familial lecithin:cholesterol acyltransferase (LCAT) deficiency (FLD) are rare disorders of lipid metabolism linked to mutations in the LCAT gene. Eleven LCAT cDNA constructs associated with FED and FLD were prepared by site-directed mutagenesis and expressed in COS-6 cells. Analysis of total RNA from wild-type, FED, and FLD transfectants revealed that all contained LCAT-specific mRNA. Western blot analysis demonstrated that all LCAT transfectants synthesized LCAT. Mean LCAT secretion by FED transfectants was slightly lower than secretion by wild-type transfectants, whereas secretion by FLD transfectants was much lower. The specific activities of FED and FLD LCAT against model high density lipoproteins were 6% and 11%, respectively, of wild-type activity. The ratios of the LCAT activities against low density lipoproteins to those against model high density lipoproteins decreased in the order FED mutants > FLD mutants approximately wild type. FED and FLD LCAT mutants are different: the former are more active against low density lipoproteins, and the latter are less secretion-competent. The greater reactivity of FED LCAT against low density lipoproteins may explain the relative mildness of the clinical manifestations of FED compared to those of FLD.

Effects of site-directed mutagenesis on the serine residues of human lecithin:cholesterol acyltransferase.

Lecithin:cholesterol acyltransferase (LCAT) is a serine protease-type enzyme that esterifies cholesterol in human plasma and is activated by apolipoprotein A-I in high-density lipoproteins. LCAT contains 22 serine residues, including Ser181, which is thought to be part of the catalytic site. In order to determine the importance of these serine residues in LCAT, we prepared six LCAT mutants: LCAT (Ser19-->Ala), LCAT (Ser181-->Gly), LCAT (Ser208-->Ala), LCAT (SEr216-->Ala), LCAT (Ser225-->Ala) and LCAT (Ser383-->Ala). We also replaced the adjacent asparagine residues in two additional mutants, LCAT (Ser19-->Ala, Asn20-->Thr) and LCAT (Ser383-->Ala, Asn384-->Thr), in order to ascertain the effect of the serines on N-glycosylation. The mutant complementary DNA (cDNA) were subcloned into a eukaryotic expression vector (pSG5) and expressed in COS-6 cells. By polymerase chain reaction analysis, LCAT-specific messenger RNA (mRNA) was found in all mutant and wild-type transfectants. Western blot analysis revealed LCAT-specific bands in media and lysates of the transfected cells. With two exceptions, the amounts of LCAT mass secreted by the transfectants were similar to that of the wild type (mean, 90% mass of wild type; range, 34-138%). Except for LCAT (Ser181-->Gly), which was inactive, the specific activities of the remainder of the mutant enzymes were also similar (mean 95% activity of wild type; range, 65-169%). These results indicate that Ser181 is part of the catalytic site and that stereoconservative substitutions for serines have minor effects on the synthesis, secretion and specific activities of human LCAT.

[Degradation of the constituents in solubilization process of donkey skin].

Dry donkey skin, defatted in advance with hair scraped off, was separately solubilized by heating in sealed tubes at 130 degrees C for 2, 4, 6, 8h. The resultants were clarified and dried as Ejiao, whose yield appeared to reach maximum after 4h heating. Absorptivities of all four Ejiao preparations were in good approximation to standard gelatin. However, their intrinsic viscosity declined in order of prolonged solubilization process, indicating that depolymerization of donkey skin gelatin had taken place. In addition, significant degradation of dermatan sulfate, another constituent of Ejiao, was detected electrophoretically and photometrically.

[Characterization and quantification of dermatan sulfate from donkey skin].

Dermatan sulfate (DS), a recently known antithrombotic glycosaminoglycan, was isolated and purified from donkey skin. Physiochemical characteristics of the glycan, including constituent analysis, electrophoretic behaviour, molecular mass, specific lyase degradations, IR and PMR spectra were described, using porcine skin-origin dermatan sulfate as a standard reference. Contents of DS in donkey skin and its gelatinized preparations (Ejiao) were also measured. Results indicate that the presence of DS may explain the long reputed clinical efficacy of donkey skin and Ejiao in treating serious symptoms associated with what has been called endogenous wind in traditional Chinese medicine.

[Comparison of protein assays for ejiao].

Ejiao exhibits identical spectral characteristics with those of reference gelatin in Murphy's UV spectrophotometry and color-yielding reactions performed according to Gornall's biuret and Lowry's Folin phenol procedures respectively. Results of protein assays of Ejiao measured by above-mentioned photometric methods were in good approximation to each other using gelatin as standard and comparable with that of Kjeldahl nitrogen determination.

Effects of site-directed mutagenesis on the N-glycosylation sites of human lecithin:cholesterol acyltransferase.

There are four potential N-glycosylation site (Asn-X-Ser/Thr) in human lecithin:cholesterol acyltransferase (LCAT, residues 20, 84, 272, and 384). To study the role of the N-linked sugars, the codon for Asn at these positions was replaced with one for Thr (AAC to ACC). The wild-type and mutant LCAT cDNAs were used to transfect COS-6 cells from which RNA was isolated; cDNAs were synthesized by reverse transcription and subjected to the polymerase chain reaction, which showed that all transfectants synthesized LCAT-specific mRNA. No intracellular or secreted LCAT was detected with the Asn272-->Thr transfectants, indicating that this residue is essential for intracellular processing. All other single-point transfectants were secretion-competent. Although there was detectable LCAT protein inside the cells and in the media of the transfectant, Asn84-->Thr, its specific activity and secreted amount were only 26% and 58% of the wild type, respectively. This implies that Asn84 is critical for full activity but not for intracellular processing. The amount secreted, specific activity, and Vmax of LCAT (Asn20-->Thr) were similar to those of the wild-type LCAT. LCAT (Asn384-->Thr) differed from the wild-type LCAT only by a lower Km. These results suggest that glycosylation at residues 20 and 384 is not essential for intracellular processing, secretion, or activity.

Roles of cysteines in human lecithin:cholesterol acyltransferase.

Human lecithin:cholesterol acyltransferase (LCAT, E.C.2.3.1.43) is a serine-type esterase that contains six cysteines, two of which, Cys31 and Cys184, are free. The remaining cysteines form disulfide links. One of these is between Cys50 and Cys74 and the other is between Cys313 and Cys356. The cDNA of LCAT and mutants in which one or two of the six cysteines were replaced by glycine was expressed in COS-6 cells. Polymerase chain reactions and Northern blot analysis indicated that LCAT mRNA was produced by all transfectants. Western blots of all transfected cells probed with a polyclonal antibody revealed intracellular LCAT. Substitution of glycine for either Cys50, Cys74, Cys313, or Cys356 was associated with a nearly total absence of activity in the medium. No protein was secreted when glycine replaced either of the amino acid residues that link Cys313 and Cys356. The small amounts of the Cys50-->Gly and Cys74-->Gly mutants found in the medium had specific activities that were much lower than that of the wild-type LCAT. All other transfectants secreted immunologically measurable amounts of active enzyme. Mutants in which one or both free cysteines, Cys31 and Cys184, were replaced with glycine were less active than the wild type and only partially inhibited by a sulfhydryl blocking reagent. The substrate specificities of the Cys31-->Gly and Cys184-->Gly mutants differed from that of the wild type.(ABSTRACT TRUNCATED AT 250 WORDS)

Biochemical evidence for the existence of thymidylate synthase in the obligate intracellular parasite Chlamydia trachomatis.

Since eucaryotic cell-derived thymidine or thymidine nucleotides are not incorporated into Chlamydia trachomatis DNA, we hypothesized that C. trachomatis must obtain dTTP for DNA synthesis by converting dUMP to dTMP. In most cells, this reaction is catalyzed by thymidylate synthase (TS) and requires 5,10-methylenetetrahydrofolate as a cofactor. We used C. trachomatis serovar L2 and a mutant CHO K1 cell line with a genetic deficiency in folate metabolism as a host for chlamydial growth. This cell line lacks a functional dihydrofolate reductase (DHFR) gene and, as a result, is unable to carry out de novo synthesis of dTTP. C. trachomatis inclusions form normally when DHFR- cells are starved for thymidine 24 h prior to and during the course of infection. When [6-3H]uridine is used as a precursor to label C. trachomatis-infected CHO DHFR- cells, radiolabel is readily incorporated into chlamydia-specific DNA. When DNA from [6-3H]uridine-labelled infected cultures is acid hydrolyzed and subjected to high-performance liquid chromatography analysis, radiolabel is detected in thymine and cytosine nucleobases. By using the DHFR- cell line as a host and [5-3H]uridine as a precursor, we could monitor intracellular C. trachomatis TS activity simply by following the formation of tritiated water. There is a good correlation between in situ TS activity and DNA synthesis activity during the chlamydial growth cycle. In addition, both C. trachomatis-specific DNA synthesis and 3H2O release are inhibited by exogenously added 5-fluorouridine but not by 5-fluorodeoxyuridine. Finally, we demonstrated in vitro TS activity in crude extracts prepared from highly purified C. trachomatis reticulate bodies. The activity is dependent on the presence of methylenetetrahydrofolic acid and can be inhibited with 5-fluoro-dUMP. Taken together, these results indicate that C. trachomatis contains a TS for the synthesis of dTMP.