[The predictive value of parathyroid hormone levels and decreases for postoperative hypocalcemia after total thyroidectomy]

Objective:To investigate the predictive value of parathyroid hormone levels and decreases for postoperative hypocalcemia after total thyroidectomy. Method:We reviewed 71 consecutive patients who underwent total thyroidectomy, measured postoperative hypocalcemia, parathyroid hormone (PTH) values within 24 hours after surgery, divided them into subgroups accroding to hypocalcemia symptom. Combining with postoperative serum calcium，postoperative PTH values and decreases (△PTH), we used the receiver operating characteristic curve (ROC) analysis to assessment of predictive value. Result:The mean value of postoperative serum calcium, postoperative PTH and △PTH between subgroups have a significant difference (P<0.01). ROC area under the curve (AUC) of △PTH is 0.9706, with cutoff value 0.7366. AUC of postoperative PTH is 0.9580, with cutoff value 14.82 ng/L. Conclusion:The postoperative PTH and △PTH is a reliable indicator to judging postoperative hypocalcemia after total thyroidectomy.

[Analysis of clinicopathological characteristics of papillary thyroid carcinoma and BRAF V600E gene mutation]

Objective: To study the correlation between the BRAF V600E mutation and the clinicopathological features of papillary thyroid carcinoma(PTC), and to explore the application value of BRAF V600E mutation in PTC. Method: The BRAF V600E gene mutation was detected in 108 PTC cases and 30 control cases by qPCR. The results were statistically analyzed by using SPSS 21.0 software. Result: The BRAF V600E mutation was absent in the control group. The BRAF V600E mutation rate was 72.20% in 108 PTC cases. Compared with patients with wild type,the mean age of patients with the mutant BRAF V600E was significantly older(P<0.05). BRAF V600E mutations were associated with PTC tissue subtypes and central area lymph node metastasis(P<0.05). BRAF V600E mutations were not correlated with tumor diameter, patient gender, multifocality, tumor site, concomitant disease, lymph node metastasis in side region of neck, capsule invasion, and TNM staging(P>0.05). Conclusion: The value of BRAF V600E mutation in the prognosis of PTC remains to be studied. BRAF V600E mutation is of value for pathological diagnosis of PTC.

Halobenzoquinone-Induced Developmental Toxicity, Oxidative Stress, and Apoptosis in Zebrafish Embryos

The developmental toxicity of water disinfection byproducts remains unclear. Here we report the study of halobenzoquinone (HBQ)-induced in vivo developmental toxicity and oxidative stress using zebrafish embryos as a model. Embryos were exposed to 0.5-10 μM of individual HBQs and 0.5-5 mM haloacetic acids for up to 120 h postfertilization (hpf). LC₅₀ values of the HBQs at 24 hpf were 4.6-9.8 μM, while those of three haloacetic acids were up to 200 times higher at 1900-2600 μM. HBQ exposure resulted in significant developmental malformations in larvae, including failed inflation of the gas bladder, heart malformations, and curved spines. An increase in reactive oxygen species was observed, together with a decrease in superoxide dismutase activity and glutathione content. Additionally, the antioxidant N-acetyl-l-cysteine significantly mitigated all HBQ-induced effects, supporting that oxidative stress contributes to HBQ toxicity. Further experiments examined HBQ-induced effects on DNA and genes. HBQ exposure increased 8-hydroxydeoxyguanosine levels, DNA fragmentation, and apoptosis in larvae, with apoptosis induction related to changes in the gene expression of p53 and mdm2. These results suggest that HBQs are acutely toxic, causing oxidative damage and developmental toxicity to zebrafish larvae.

Quantitative synthesis of protein-DNA conjugates with 1 : 1 stoichiometry

We describe here a binding-facilitated reaction strategy, enabling quantitative conjugation of DNA to native proteins with a desirable 1 : 1 stoichiometry. The technique takes advantage of the iterative affinity interaction and covalent binding processes to achieve complete conjugation. The complete conjugation obviates the need for separation of the protein-DNA conjugates as required by other DNA-protein conjugation methods.

[Analysis on the factors related to the immediate success rate of radiofrequency catheter ablation on patients with idiopathic right ventricular outflow tract ventricular arrhythmia]

Objective: To analyze the clinical characteristics of patients with idiopathic right ventricular outflow tract (RVOT) ventricular arrhythmias (VA) and factors related to the immediate success rate of radiofrequency ablation. Methods: Patients diagnosed as idiopathic RVOT arrhythmia in Fuwai Hospital from February 2009 to January 2013 were retrospectively screened. Patients with structural heart disease or inherited arrhythmia were excluded. All patients underwent endocardial electrophysiological study and radiofrequency catheter ablation. Baseline clinical and operation records were collected and analyzed. Immediate success rate was defined as no inducible ventricular arrhythmia by isoprinosine and electrophysiological induction at the end of ablation. The origins of idiopathic RVOT were classified as septal, anterior, posterior, free wall site, epicardial and RVOT-aorta root site. Results: A total of 468 patients were finally included, and the age was (40.4±13.3) years old and 60.5%(283/468) patients were female. Immediate radiofrequency success rate was 89.3%(418/468). Patients were divided into ablation success group (n=418) and ablation failure group (n=50). Percent of female patients and patients with interventricular septal origin was significantly higher in the ablation success group than in ablation failure group (261(62.4%) vs. 22 (44.0%) , P=0.01, and 233(55.7%) vs. 18(36.0%), P=0.005), while percent of patients with epicardial origin was significantly lower in the ablation success group than in ablation failure group (17(4.1%) vs. 11(22.0%), P<0.001). Immediate success rate was the highest for patients with the septal origin and the lowest for patients with epicardial origin (92.8%(233/251) vs. 60.7%(17/28), P<0.05). Multivariate analysis showed that the origin site of VAs was the most important independent factor related to the success rate of ablation. Compared with the septal origin patients, patients with RVOT-aorta root and epicardial origin VAs faced with 1.82-fold and 8.26-fold increased risk of failed ablation, respectively (OR=2.82, 95%CI 1.05-7.57, and OR=9.26, 95%CI 3.60-23.86). Sex category was not the independent risk factor for failed ablation(OR=1.76, 95%CI 0.93-3.33, P=0.08) . Conclusions: The immediate success rate of radiofrequency catheter ablation for idiopathic RVOT ventricular arrhythmia is relative high, however, immediate success rate of radiofrequency catheter ablation is relatively low for patients with epicardial and RVOT-aorta root origin arrhythmia and VAs origin is an independent risk factor of immediate ablation success rate.

Halobenzoquinone-Induced Alteration of Gene Expression Associated with Oxidative Stress Signaling Pathways

Halobenzoquinones (HBQs) are emerging disinfection byproducts (DBPs) that effectively induce reactive oxygen species and oxidative damage in vitro. However, the impacts of HBQs on oxidative-stress-related gene expression have not been investigated. In this study, we examined alterations in the expression of 44 genes related to oxidative-stress-induced signaling pathways in human uroepithelial cells (SV-HUC-1) upon exposure to six HBQs. The results show the structure-dependent effects of HBQs on the studied gene expression. After 2 h of exposure, the expression levels of 9 to 28 genes were altered, while after 8 h of exposure, the expression levels of 29 to 31 genes were altered. Four genes ( HMOX1, NQO1, PTGS2, and TXNRD1) were significantly upregulated by all six HBQs at both exposure time points. Ingenuity pathway analysis revealed that the Nrf2 pathway was significantly responsive to HBQ exposure. Other canonical pathways responsive to HBQ exposure included GSH redox reductions, superoxide radical degradation, and xenobiotic metabolism signaling. This study has demonstrated that HBQs significantly alter the gene expression of oxidative-stress-related signaling pathways and contributes to the understanding of HBQ-DBP-associated toxicity.

Formation and Occurrence of Iodinated Tyrosyl Dipeptides in Disinfected Drinking Water

Iodinated disinfection byproducts (I-DBPs) are highly toxic, but few precursors of I-DBPs have been investigated. Tyrosine-containing biomolecules are ubiquitous in surface water. Here we investigated the formation of I-DBPs from the chloramination of seven tyrosyl dipeptides (tyrosylglycine, tyrosylalanine, tyrosylvaline, tyrosylhistidine, tyrosylglutamine, tyrosylglutamic acid, and tyrosylphenylalanine) in the presence of potassium iodide. High resolution mass spectrometry and tandem mass spectrometry (MS/MS) analyses of the benchtop reaction solutions found that all seven precursors formed both I- and Cl-substituted tyrosyl dipeptide products. Iodine substitutions occurred on the 3- and 3,5-positions of the tyrosyl-phenol ring while chlorine substituted on the free amino group. To reach the needed sensitivity to detect iodinated tyrosyl dipeptides in authentic waters, we developed a high performance liquid chromatography (HPLC)-MS/MS method with multiple reaction monitoring mode and solid phase extraction. HPLC-MS/MS analysis of tap and corresponding raw water samples, collected from three cities, identified four iodinated peptides, 3-I-/3,5-di-I-Tyr-Ala and 3-I-/3,5-di-I-Tyr-Gly, in the tap waters but not in the raw waters. The corresponding precursors, Tyr-Ala and Tyr-Gly, were also detected in the same tap and raw water samples. This study demonstrates that iodinated dipeptides exist as DBPs in drinking water.

Characterization of Mechanisms of Glutathione Conjugation with Halobenzoquinones in Solution and HepG2 Cells

Halobenzoquinones (HBQs) are a class of emerging disinfection byproducts. Chronic exposure to chlorinated drinking water is potentially associated with an increased risk of human bladder cancer. HBQ-induced cytotoxicity involves depletion of cellular glutathione (GSH), but the underlying mechanism remains unclear. Here we used ultrahigh performance liquid chromatography-high resolution mass spectrometry and electron paramagnetic resonance spectroscopy to study interactions between HBQs and GSH and found that HBQs can directly react with GSH, forming various glutathionyl conjugates (HBQ-SG) in both aqueous solution and HepG2 cells. We found that the formation of HBQ-SG varies with the initial molar ratio of GSH to HBQ in reaction mixtures. Higher molar ratios of GSH to HBQ facilitate the conjugation of more GSH molecules to an HBQ molecule. We deduced the reaction mechanism between GSH and HBQs, which involves redox cycling-induced formation of halosemiquinone (HSQ) free radicals and glutathione disulfide, Michael addition, as well as nucleophilic substitution. The proposed reaction rates are in the following order: formation of HSQ radicals > substitution of bromine by GSH > Michael addition of GSH on the benzoquinone ring > substitution of chlorine by GSH > substitution of the methyl group by GSH. The conjugates identified in HBQ-treated HepG2 cells were the same as those found in aqueous solution containing a 5:1 ratio of GSH:HBQs.

Drinking Water Disinfection Byproducts (DBPs) and Human Health Effects: Multidisciplinary Challenges and Opportunities

While drinking water disinfection has effectively prevented waterborne diseases, an unintended consequence is the generation of disinfection byproducts (DBPs). Epidemiological studies have consistently observed an association between consumption of chlorinated drinking water with an increased risk of bladder cancer. Out of the >600 DBPs identified, regulations focus on a few classes, such as trihalomethanes (THMs), whose concentrations were hypothesized to correlate with the DBPs driving the toxicity of disinfected waters. However, the DBPs responsible for the bladder cancer association remain unclear. Utilities are switching away from a reliance on chlorination of pristine drinking water supplies to the application of new disinfectant combinations to waters impaired by wastewater effluents and algal blooms. In light of these changes in disinfection practice, this article discusses new approaches being taken by analytical chemists, engineers, toxicologists and epidemiologists to characterize the DBP classes driving disinfected water toxicity, and suggests that DBP exposure should be measured using other DBP classes in addition to THMs.

Formation of water disinfection byproduct 2,6-dichloro-1,4-benzoquinone from chlorination of green algae

We report that green algae in lakes and rivers can serve as precursors of halobenzoquinone (HBQ) disinfection byproducts (DBPs) produced during chlorination. Chlorination of a common green alga, Chlorella vulgaris, produced 2,6-dichloro-1,4-benzoquinone (2,6-DCBQ), the most prevalent HBQ DBP in disinfected water. Under varying pH conditions (pH6.0-9.0), 2,6-DCBQ formation ranged from 0.3 to 2.1μg/mg C with maximum formation at pH8.0. To evaluate the contribution of organic components of C. vulgaris to 2,6-DCBQ formation, we separated the organics into two fractions, the protein-rich fraction of intracellular organic matter (IOM) and the polysaccharide-laden fraction of extracellular organic matter (EOM). Chlorination of IOM and EOM produced 1.4μg/mg C and 0.7μg/mg C of 2,6-DCBQ, respectively. The IOM generated a two-fold higher 2,6-DCBQ formation potential than the EOM fraction, suggesting that proteins are potent 2,6-DCBQ precursors. This was confirmed by the chlorination of proteins extracted from C. vulgaris: the amount of 2,6-DCBQ produced is linearly correlated with the concentration of total algal protein (R²=0.98). These results support that proteins are the primary precursors of 2,6-DCBQ in algae, and control of green algal bloom outbreaks in source waters is important for management of HBQ DBPs.

[Association between small dense low-density lipoprotein cholesterol and carotid atherosclerosis]

Objective: To explore the association between small dense low-density lipoprotein cholesterol (sdLDL-C) and carotid atherosclerosis. Methods: 1 578 subjects were enrolled in an annual health check-up program in aerospace center hospital from 2016 to 2017, and these patients were divided into 471 cases (men 343 and women 128) with carotid atherosclerosis (subjects with increased carotid artery intima-media thickness or carotid atherosclerosis plaque) and 1 107 cases (men 567 and women 540) with non- carotid atherosclerosis according to ultrasonography. Serum sdLDL-C levels were measured by peroxidase assay. Results: Serum sdLDL-C was significantly higher in carotid atherosclerosis group (1.11±0.44) mmol/L than that in non-carotid group (0.88±0.40) mmol/L, with significant difference (t=9.856, P<0.001). Stratified by quartiles of sdLDL-C (Q1-Q4), the prevalence of carotid atherosclerosis was significantly increased trend along with increased sdLDL-C levels (P<0.001). In multivariate Logistic regression analysis, after adjustment for age, sex and other traditional atherosclerosis risk factors, comparing Q4 with Q1, the odd ratio of prevalence of carotid atherosclerosis was 5.164, and 95% confidence interval(CI) was 2.833-9.413. While the sdLDL-C threshold was 0.727 mmol/L as the optimal cut-off point, the clinical sensitivity and specificity of sdLDL-C for screening carotid atherosclerosis were 80.5% and 41.4%, respectively. Conclusion: Serum sdLDL-C was an independent risk factor of carotid atherosclerosis. sdLDL-C may be a potentially useful risk marker in early screening for carotid atherosclerosis.

[Association between serum adipocyte fatty acid binding protein level and insulin resistance in patients with OSAS]

Objective: To investigate the association between serum adipocyte fatty acid binding protein (A-FABP) level and insulin resistance in patients with obstructive sleep apnea syndromes (OSAS). Methods: Eighty patients with snoring were monitored by overnight polysomnography (PSG) from September 2015 to July 2017, and there were 59 males and 21 females, aged from 22 to 77 years old (mean age 47±14 years old). Based on the apnea-hypopnea index (AHI), these patients were divided into three groups: primary snoring group (AHI<5/h, n=19), mild-moderate OSAS groups (5/h≤AHI≤30/h, n=23) and severe OSAS groups (AHI>30/h, n=38). The levels of A-FABP, the fasting plasma glucose (FPG), fasting insulin (FINS) and insulin resistance index (IRI) were compared between the primary snoring group and OSAS patients with different severities, and the correlations between serum A-FABP and IRI as well as PSG parameters were further evaluated using partial correlation analysis. Results: Compared with the primary snoring group [(15.6±3.5) μg/L] and mild-moderate group [(17.4±4.3) μg/L], there was a significant increase of the serum A-FABP level in the severe OSAS group [(21.4±4.6) μg/L](P=0.001, P=0.025). Additionally, after adjustment for BMI and age, serum A-FABP level showed significant positive correlations with FINS and IRI (r=0.478, P<0.001; r=0.356, P=0.035); serum A-FABP level was positively correlated with AHI and the arterial oxygen saturation (SaO(2)) < 90% time ratio in night (TS90%) (r=0.251, P=0.041 and r=0.271, P=0.035). Nevertheless, serum A-FABP level showed significant negative correlation with the lowest SaO(2) and the mean SaO(2) (r=-0.244, P=0.038 and r=-0.280, P=0.018). Conclusion: Insulin resistance and the increased level of serum A-FABP are common in OSAS patients, the level of serum A-FABP is significantly correlated with insulin resistance and nocturnal intermittent hypoxia, both of which suggest that A-FABP plays a potential role in insulin resistance in patients with OSAS.

Effect of iron source on iron absorption and gene expression of iron transporters in the ligated duodenal loops of broilers

This experiment was conducted to investigate the effect of iron source on Fe absorption and the gene expression of divalent metal transporter 1 (DMT1) and ferroportin 1 (FPN1) in the ligated duodenal loops of broilers. The in situ ligated duodenal loops from Fe-deficient broiler chicks (28-d-old) were perfused with Fe solutions containing 0 to 14.33 mmol Fe/L from 1 of the following: Fe sulfate (FeSO∙7HO), Fe methionine with weak chelation strength (Fe-Met W; chelation strength is expressed as quotient of formation [Q] value, Q = 1.37), Fe proteinate with moderate chelation strength (Fe-Prot M; Q = 43.6), and Fe proteinate with extremely strong chelation strength (Fe-Prot ES; Q = 8,590) for up to 30 min. The gene expression of DMT1 and FPN1 in the duodenal loops from the control group and the groups treated with 3.58 mmol Fe/L from 1 of 4 Fe sources was analyzed. The absorption kinetics of Fe from different Fe sources in the duodenum followed a saturated carrier-dependent transport process. The maximum transport rate (J) values in the duodenum were greater ( < 0.03) for Fe-Prot ES and Fe-Prot M than for Fe-Met W and FeSO∙7HO. The Fe perfusion inhibited ( < 0.05) the mRNA expression of but enhanced ( < 0.0008) the mRNA expression of in the duodenum and had no effect ( > 0.14) on the protein expression levels of the 2 transporters. These results indicated that organic Fe sources with greater Q values showed higher Fe absorption; however, all Fe sources followed the same saturated carrier-dependent transport process in the duodenum, and DMT1 and FPN1 might participate in Fe absorption in the duodenum of broilers regardless of Fe source.

Effects of halobenzoquinone and haloacetic acid water disinfection byproducts on human neural stem cells

Human neural stem cells (hNSCs) are a useful tool to assess the developmental effects of various environmental contaminants; however, the application of hNSCs to evaluate water disinfection byproducts (DBPs) is scarce. Comprehensive toxicological results are essential to the prioritization of DBPs for further testing and regulation. Therefore, this study examines the effects of DBPs on the proliferation and differentiation of hNSCs. Prior to DBP treatment, characteristic protein markers of hNSCs from passages 3 to 6 were carefully examined and it was determined that hNSCs passaged 3 or 4 times maintained stem cell characteristics and can be used for DBP analysis. Two regulated DBPs, monobromoacetic acid (BAA) and monochloroacetic acid (CAA), and two emerging DBPs, 2,6-dibromo-1,4-benzoquinone (2,6-DBBQ) and 2,6-dichloro-1,4-benzoquinone (2,6-DCBQ), were chosen for hNSC treatment. Both 2,6-DBBQ and 2,6-DCBQ induced cell cycle arrest at S-phase at concentrations up to 1μmol/L. Comparatively, BAA and CAA at 0.5μmol/L affected neural differentiation. These results suggest DBP-dependent effects on hNSC proliferation and differentiation. The DBP-induced cell cycle arrest and inhibition of normal hNSC differentiation demonstrate the need to assess the developmental neurotoxicity of DBPs.

Methylated Phenylarsenical Metabolites Discovered in Chicken Liver

We report the discovery of three toxicologically relevant methylated phenylarsenical metabolites in the liver of chickens fed 3-nitro-4-hydroxyphenylarsonic acid (ROX), a feed additive in poultry production that is still in use in several countries. Methyl-3-nitro-4-hydroxyphenylarsonic acid (methyl-ROX), methyl-3-amino-4-hydroxyphenylarsonic acid (methyl-3-AHPAA), and methyl-3-acetamido-4-hydroxyphenylarsonic acid (or methyl-N-acetyl-ROX, methyl-N-AHPAA) were identified in such chicken livers, and the concentration of methyl-ROX was as high as 90 μg kg^-1 , even after a five-day clearance period. The formation of these newly discovered methylated metabolites from reactions involving trivalent phenylarsonous acid substrates, S-adenosylmethionine, and the arsenic (+3 oxidation state) methyltransferase enzyme As3MT suggests that these compounds are formed by addition of a methyl group to a trivalent phenylarsenical substrate in an enzymatic process. The IC₅₀ values of the trivalent phenylarsenical compounds were 300-30 000 times lower than those of the pentavalent phenylarsenicals.