Amlodipine inhibits the proliferation and migration of esophageal carcinoma cells through the induction of endoplasmic reticulum stress.

BACKGROUND: L-type calcium channels are the only protein channels sensitive to calcium channel blockers, and are expressed in various cancer types. The Cancer Genome Atlas database shows that the mRNA levels of multiple L-type calcium channel subunits in esophageal squamous cell carcinoma tumor tissue are significantly higher than those in normal esophageal epithelial tissue. Therefore, we hypothesized that amlodipine, a long-acting dihydropyridine L-type calcium channel blocker, may inhibit the occurrence and development of esophageal cancer (EC). AIM: To investigate the inhibitory effects of amlodipine on EC through endoplasmic reticulum (ER) stress. METHODS: Cav1.3 protein expression levels in 50 pairs of EC tissues and corresponding paracancerous tissues were examined. Subsequently, the inhibitory effects of amlodipine on proliferation and migration of EC cells in vitro were detected using 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide and Transwell assays. In vivo experiments were performed using murine xenograft model. To elucidate the underlying mechanisms, in vitro cell studies were performed to confirm that ER stress plays a role in inhibition proliferation and migration of EC cells treated with amlodipine. RESULTS: The expression level of Cav1.3 in esophageal carcinoma was 1.6 times higher than that in paracancerous tissues. Amlodipine treatment decreased the viability of esophageal carcinoma cells in a dose- and time-dependent manner. In vivo animal experiments also clearly indicated that amlodipine inhibited the growth of EC tumors in mice. Additionally, amlodipine reduces the migration of tumor cells by inhibiting epithelial-mesenchymal transition (EMT). Mechanistic studies have demonstrated that amlodipine induces ER stress-mediated apoptosis and suppresses EMT. Moreover, amlodipine-induced autophagy was characterized by an increase in autophagy lysosomes and the accumulation of light chain 3B protein. The combination of amlodipine with the ER stress inhibitor 4-phenylbutyric acid further confirmed the role of the ER stress response in amlodipine-induced apoptosis, EMT, and autophagy. Furthermore, blocking autophagy increases the ratio of apoptosis and migration. CONCLUSION: Collectively, we demonstrate for the first time that amlodipine promotes apoptosis, induces autophagy, and inhibits migration through ER stress, thereby exerting anti-tumor effects in EC.

Ramulus Mori (Sangzhi) Alkaloids Ameliorate Obesity-Linked Adipose Tissue Metabolism and Inflammation in Mice.

Obesity has become a global epidemic disease as it is closely associated with a chronic low-grade inflammatory state that results in metabolic dysfunction. Ramulus Mori (Sangzhi) alkaloids (SZ-A) derived from Morus alba L. were licensed to treat type 2 diabetes (T2DM) in 2020. In this study, we explored the effect of SZ-A on adipose tissue metabolism and inflammation using an obesity model induced by a high-fat diet (HFD). C57BL/6J mice were fed high fat for 14 weeks and followed by SZ-A 400 mg/kg treatment via gavage for another six weeks, during which they were still given the high-fat diet. The results showed that SZ-A notably reduced body weight and serum levels of lipid metabolism-related factors, such as triglycerides (TG) and total cholesterol (TC); and inflammation-related factors, namely tumor necrosis factor alpha (TNFα), interleukin 6 (IL6), fibrinogen activator inhibitor-1 (PAI-1), angiopoietin-2 (Ang-2), and leptin (LEP), in the HFD-induced mice. SZ-A increased the protein and mRNA expression of lipid metabolism-related factors, including phosphorylated acetyl coenzyme A carboxylase (p-ACC), phosphorylated hormone-sensitive triglyceride lipase (p-HSL), adipose triglyceride lipase (ATGL), and peroxisome proliferator-activated receptor-alpha (PPARα), in adipose tissue. Immunohistochemistry results demonstrated that SZ-A significantly reduced the infiltration of pro-inflammatory M1-type macrophages in epididymal fat. The data also suggested that SZ-A down-regulates the transcriptional levels of inflammatory factors Il6, Tnfα, monocyte chemoattractant protein-1 (Mcp1), and F4/80, and up-regulates interleukin 4 (Il4), interleukin 10 (Il10), and interleukin 13 (Il13) in adipose tissue. Overall, the results indicate that SZ-A exhibits potential in regulating lipid metabolism and ameliorating obesity-linked adipose inflammation.

Ramulus Mori (Sangzhi) Alkaloids Alleviate High-Fat Diet-Induced Obesity and Nonalcoholic Fatty Liver Disease in Mice.

Nonalcoholic fatty liver disease (NAFLD), obesity, and type 2 diabetes mellitus (T2DM) have highly related mechanisms. Ramulus Mori (Sangzhi) alkaloids (SZ-A) from Morus alba L. were approved in 2020 for the treatment of T2DM. In this study, we examined the therapeutic effects and mechanism of SZ-A on obesity and NAFLD in mice. Mice (C57BL/6J) fed a high-fat diet (HFD) for 14 weeks were treated with SZ-A for another 6 weeks. HFD-induced weight gain was reduced by SZ-A in a dose-dependent manner. SZ-A treatment significantly stimulated adiponectin expression and secretion in adipose tissue and 3T3-L1 adipocytes. Additionally, SZ-A markedly reduced hepatic steatosis (triglyceride, total cholesterol) and expression of pro-inflammatory and pro-fibrotic genes. SZ-A regulated lipid metabolism and oxidative stress (malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GPx), and glutathione (GSH)) in the liver. Palmitic acid-induced insulin resistance and lipid accumulation in HepG2 cells were also repressed by SZ-A. Collectively, SZ-A protected mice from HFD-induced NAFLD through an indirect effect of improved systemic metabolism reducing bodyweight, and a direct effect by enhancing the lipid metabolism of HepG2 cells. The weight-loss effect of SZ-A in mice was partly due to improved fatty oxidation instead of influencing food consumption.

Differences in maternal characteristics and pregnancy outcomes between syphilitic women with and without partner coinfection.

BACKGROUND: Partner infection is a significant factor in preventing mother-to-child syphilis transmission. We compared pregnancy outcomes between syphilis discordant and syphilis concordant couples. METHODS: We conducted a retrospective study among 3076 syphilis-positive women who received syphilis screening together with their partners during pregnancy. Multivariate analysis was used to explore risks for abnormal outcomes in objects correcting for the major covariate factors. Adjusted odds ratios (OR) and 95% confidence intervals (CI) were estimated to compare pregnancy outcomes between syphilis concordant and syphilis discordant couples. RESULTS: Overall, 657 of the 3076 women were diagnosed with gestational syphilis and had a syphilis-positive partner, giving a partner concordance prevalence of 21.36%. Women in concordant couples were more likely to have higher parity, more children, late antenatal care and syphilis screening, a lower proportion of latent syphilis, and elevated serologic titers than women in discordant couples (P < 0.01 for all). Totally, 10.08% of women had adverse pregnancy outcomes. Multivariate analysis showed partners' syphilis infection (ORadj = 1.44, 95% CI: 1.10-1.89), untreated pregnancy syphilis (ORadj = 1.67, 95% CI: 1.15-2.43), and higher maternal serum titers (> 1:8) (ORadj = 1.53, 95% CI: 1.17-2.00) increased the risks of adverse pregnancy outcomes. Concordance was associated with increased risk for stillbirth (ORadj = 2.86, 95%CI:1.36-6.00), preterm birth (PTB) (ORadj = 1.38,95%CI:1.02-1.87) and low birth weight (LBW) (ORadj = 1.55, 95%CI:1.13-2.11) compared with discordance. Even among treated women, concordance was associated with increased risk for stillbirth (ORadj = 3.26, 95%CI:1.45-7.31) and LBW (ORadj = 1.52, 95%CI:1.08-2.14). Among women with one treatment course, the risks for PTB(ORadj = 1.81, 95%CI:1.14-2.88) and LBW(ORadj = 2.08, 95%CI:1.28-3.38)were also higher among concordant couples than discordant couples. Nevertheless, there were no significant differences between concordant and discordant couples in risks of stillbirth (ORadj = 2.64, 95% CI: 0.98-7.05),PTB (ORadj = 1.15, 95% CI: 0.76-1.74), and LBW(ORadj = 1.21, 95% CI: 0.78-2.02) among women with two treatment courses. CONCLUSION: Male partner coinfection increased the risks for stillbirth, PTB and LBW, particularly when gestational syphilis treatment was suboptimal. However, this risk could be reduced by adequate treatment.

Calcium-Activated Chloride Channel A4 (CLCA4) Plays Inhibitory Roles in Invasion and Migration Through Suppressing Epithelial-Mesenchymal Transition via PI3K/AKT Signaling in Colorectal Cancer.

BACKGROUND Calcium-activated chloride channel A4 (CLCA4) is known as a tumor suppressor which contributes to the progression of a number of types of malignant tumors. However, little is known about the functional roles of CLCA4 in colorectal cancer (CRC). MATERIAL AND METHODS In this study, the expression patterns and dysregulation of mRNAs in CRC tissues were profiled by analyzing GSE21510 datasets from Gene Expression Omnibus database which contains 104 primary hepatocellular carcinoma tissues and 24 normal liver tissues, and by performing Kaplan-Meier analysis of TCGA data. Additionally, immunohistochemistry and quantitative real-time polymerase chain reaction (qRT-PCR) were performed using clinical tissues collected at our institute. In order to explore the functional role of CLCA4, gain-of-function cell models were constructed in SW620 and LoVo cells. Wound healing assay and Transwell assay were carried out to access the cell migration and invasion ability. RESULTS It was found that CLCA4 was an independent predictor for overall survival and lymph node metastasis. Additionally, immunohistochemistry and qRT-PCR results of the clinical tissues collected as part of our study further confirmed this correlation. In vitro experiments demonstrated that over-expression of CLCA4 could inhibit cell migration and invasion by suppressing epithelial-mesenchymal transition (EMT) via PI3K/ATK signaling and change the expression patterns of EMT markers in CLCA4-gain-of-function cell models. CONCLUSIONS CLCA4 inhibits migration and invasion by suppressing EMT via PI3K/ATK signaling and predicts favorable prognosis of CRC which may help to distinguish potential risk of lymph node metastasis in CRC.

Prevalence, types, and malformations in congenital anomalies of the kidney and urinary tract in newborns: a retrospective hospital-based study.

BACKGROUND: Congenital anomalies of the kidney and urinary tract (CAKUTs) are some of the most common birth defects affecting newborns. CAKUTs often have poor birth outcomes owing to the limited experience of physicians in developing countries regarding antenatal and postnatal diagnosis. We aimed to estimate the epidemiology of CAKUTs using data from a hospital-based registry in Zhejiang Province, China. METHODS: We included a total of 2790 newborns with CAKUTs, identified among 1,748,038 births during 2010-2016. The prevalence and type of CAKUTs, maternal and neonatal characteristics, and associated malformations were analyzed. RESULTS: The average prevalence of CAKUTs born to mothers overall and mothers aged ≥35 years were both around 1.60 per 1000 births (95% confidence interval (CI), 1.54-1.66; 95% CI, 1.44-1.83, respectively) during the study period. The prevalence of CAKUTs changed over time among all women and women of advanced maternal age, although no significant trends were observed. CAKUTs were more likely to occur in male than female newborns (odds ratio (OR) 1.28, 95% CI 1.18-1.38), in multiple births than singletons (OR 1.53, 95% CI 1.21-1.92) and in urban areas than rural areas (OR 1.27, 95% CI 1.18-1.37). The overall prenatal detection rate of CAKUTs was 73.87%. The average gestational age at antenatal diagnosis was 26.57 ± 8.70 weeks. A total 22.69% CAKUTs had associated malformations. Congenital heart defects were the most common anomalies, accounting for 8.89% of the whole population. The main proportion in subgroups was hydronephrosis, representing 31.79% of registered CAKUTs. CONCLUSIONS: There was a nearly twofold increase in the prevalence of CAKUTs from 2010 to 2016 in Zhejiang Province. CAKUTs are strongly associated with male sex, multiple births, urban areas, and other nonurinary congenital malformations.

Enhanced cleanup efficiency hydroxy functionalized-magnetic graphene oxide and its comparison with magnetic carboxyl-graphene for PRiME pass-through cleanup of strychnine and brucine in human plasma samples.

An enhanced cleanup efficiency hydroxy functionalized-magnetic graphene oxide (EH-Mag-GO) fully covered porous nano-titania as coating has been designed and synthesized. It has been evaluated in PRiME (process, robustness, improvements, matrix effects, ease of use) pass-through cleanup procedure for human plasma prior to analysis of strychnine and brucine by liquid chromatography-tandem quadrupole mass spectrometry (LC-MS/MS). Comparing with the magnetic carboxyl-graphene (Mag-CG), EH-Mag-GO is much more effective for the removal of matrix effect resulted from blood phospholipids. Under optimal conditions, the results show higher cleanup efficiency of EH-Mag-GO with recoveries in the range of 89.4%-118%. The limits of quantification (LOQs) for strychnine and brucine are 0.088 µg/L and 0.092 µg/L, respectively. Especially, the EH-Mag-GO is also evaluated for reuse (20 times) without much sacrifice of the cleanup efficiency. Validation results on linearity, specificity, accuracy and precision, as well as on the application to analysis of strychnine and brucine in six cases of suspected semen strychni poisoning demonstrate the applicability to clinical studies.

Effect of different treatments and alcohol addiction on gut microbiota in minimal hepatic encephalopathy patients.

Minimal hepatic encephalopathy (MHE) is caused by dysbiosis of gut microbiota, particularly the ammonia-producing bacteria. Given the efficacy of certain treatments on MHE and the connection between alcoholism and MHE, a thorough understanding of how these strategies affect the gut microbiota in patients (alcoholic or non-alcoholic) will facilitate the assessment of their efficacy in the reshaping of gut microbiota. In the present study, a metagenomics approach was adopted to reveal alterations in gut microbiota of 14 MHE patients following treatment with rifaximin alone or rifaximin plus probiotics. Patients were grouped into the alcoholic and non-alcoholic groups to examine differences in terms of their response to treatment. Treatment reduced the overall microbiota diversity and decreased the abundance of certain ammonia-producing bacteria, such as Clostridium, with the treatment of rifaximin plus probiotics presenting a more apparent effect. Non-alcoholic MHE patients responded better to the treatment, as they presented greater reduction in microbiota diversity and a more consistent decline in certain ammonia-producing bacteria genera (such as Clostridium and Streptococcus) belonging to the Firmicutes phylum. In conclusion, treatment with rifaximin alone and rifaximin plus probiotics exhibited a different effect in different MHE patients, decreasing the overall gut microbiota diversity to various extents and reshaping microbiota in different ways. Furthermore, non-alcoholic MHE patients responded better to treatment in microbiota alterations.

Application of carbon nanosorbent for PRiME pass-through cleanup of 10 selected local anesthetic drugs in human plasma samples.

A novel PRiME (process, robustness, improvements, matrix effects, ease of use) pass-through cleanup procedure has been developed to improve the existing commercially available designs. Carbon nanosorbents, i.e., magnetic modified carboxyl-graphene (Mag-CG) and magnetic modified carboxyl-carbon nanotubes (Mag-CCNTs), have been synthesised and evaluated in PRiME pass-through cleanup procedure for human plasma prior to analysis of 10 selected local anesthetic drugs by liquid chromatography-tandem quadrupole mass spectrometry (LC-MS/MS). The matrix effect, an interesting phenomenon of ion suppression for local anesthetic drugs containing ester group and ion enhancement for other drugs containing acylamino group, has been minimized using carbon nanosorbents PRiME pass-through cleanup procedure. Under the optimal conditions, the obtained results show higher cleanup efficiency of the carbon nanosorbents with recoveries between 70.2% and 126%. Furthermore, the carbon nanosorbents are also evaluated for reuse up to 80-100 times. The limits of quantification (LOQs) for local anesthetic drugs are in the range of 0.024-0.15 µg/L. Validation results on linearity, specificity, accuracy, and precision, as well as the application to the analysis of lidocaine in five patients recruited from the lung cancer demonstrate the applicability to clinical studies.

Fast determination of catecholamines in human plasma using carboxyl-functionalized magnetic-carbon nanotube molecularly imprinted polymer followed by liquid chromatography-tandem quadrupole mass spectrometry.

A novel, simple and sensitive method based on the use of dispersive micro-solid-phase extraction (d-µ-SPE) procedure combined with ultra-fast liquid chromatography-tandem quadrupole mass spectrometry (UFLC-MS/MS) for the determination of catecholamines, i.e., dopamine (DA), norepinephrine(NE) and epinephrine (E), was developed and validated. The novel catecholamines molecularly imprinted polymer (MIP) on the surface of carboxyl-functionalized magnetic-carbon nanotube (CF@m-CNTs-MIP) was synthesized and characterized by vibrating sample magnetometer (VSM), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The CF@m-CNTs-MIP was used as the d-µ-SPE sorbent to extract catecholamines from human plasma samples. The obtained results demonstrated the higher extraction capacity of CF@m-CNTs-MIP with recoveries between 87.5-110%. The limits of quantification (LOQs) for NE, E and DA were 76 ng/L, 18 ng/L and 10 ng/L, respectively. Validation results on linearity, specificity, accuracy, precision and stability, as well as on application to the analysis of catecholamines in 120 healthy volunteers demonstrated the applicability to clinical studies.

Primary hepatic angiosarcoma: A report of two cases and literature review.

Primary hepatic angiosarcoma (PHA) is a rare malignancy that carries a poor prognosis. Of 1500 patients who underwent hepatectomy for primary hepatic tumors between 1994 and 2013 at our center, two patients were pathologically diagnosed with PHA. Clinical characteristics, treatment modalities, and outcomes of the two patients were collected and analyzed. Both patients underwent hepatectomy and had a postoperative survival time of 8 and 16 mo, respectively. A search of PubMed yielded eight references reporting 35 cases of PHA published between 2004 and 2013. On the basis of the presented cases and review of the literature, we endorse complete surgical resection as the mainstay definitive treatment of PHA, with adjuvant postoperative chemotherapy potentially improving survival. Palliative chemotherapy is an option in advanced hepatic angiosarcoma.

A new alternative paraffinic-palmbiodiesel fuel for reducing polychlorinated dibenzo-p-dioxin/dibenzofuran emissions from heavy-duty diesel engines.

Polychlorinated dibenzo-p-dioxin/dibenzofuran (PCDD/F) emissions from heavy-duty diesel engines (HDDEs) fuelled with paraffinic-palmbiodiesel blends have been rarely addressed in the literature. A high-resolution gas chromatograph/high-resolution mass spectrometer (HRGC/HRMS) was used to analyze 17 PCDD/F species. Experimental results indicate that the main species of PCDD/Fs were OCDD (octachlorinated debenzo-p-dioxin) and OCDF (octachlorodibenzofuran), and they accounted for 40-50% of the total PCDD/Fs for all test fuels. Paraffinic-palmbiodiesel blends decreased PCDD/Fs by 86.1-88.9%, toxic PCDD/Fs by 91.9-93.0%, THC (total hydrocarbons) by 13.6-23.3%, CO (carbon monoxide) by 27.2-28.3%, and PM (particulate matter) by 21.3-34.2%. Using biodiesel blends, particularly BP9505 or BP8020, instead of premium diesel fuel (PDF) significantly reduced emissions of both PCDD/Fs and traditional pollutants. Using BP9505 (95vol% paraffinic fuel+5vol% palmbiodiesel) and BP8020 instead of PDF can decrease PCDD/F emissions by 5.93 and 5.99gI-TEQyear(-1) in Taiwan, respectively.

Kinetics of cell lysis for Microcystis aeruginosa and Nitzschia palea in the exposure to ß-cyclocitral.

The effect of an algal metabolite, ß-cyclocitral, on the cell integrity of two cyanobacteria and one diatom was investigated. The cyanobacteria, Microcystis aeruginosa PCC 7005 and PCC 7820, and the diatom, Nitzschia palea, were exposed to various concentrations of ß-cyclocitral. Scanning electron microscope (SEM) results indicate that the cells of tested species were greatly altered after being exposed to ß-cyclocitral. A flow cytometer coupled with the SYTOX stain and chlorophyll-a auto-fluorescence was used to quantify the effect of ß-cyclocitral on cell integrity for the tested cyanobacteria and diatom. Kinetic experiments show that about 5-10 mg L(-1) of ß-cyclocitral for the two M. aeruginosa strains and a much lower concentration, 0.1-0.5 mg L(-1), for N. palea were needed to cause 15-20% of cells to rupture. When the ß-cyclocitral concentration was increased to 200-1000 mg L(-1) for M. aeruginosa and 5-10 mg L(-1) for N. palea, almost all the cells ruptured between 8 and 24h. A first-order kinetic model is able to describe the data of cell integrity over time. The extracted rate constant values well correlate with the applied ß-cyclocitral dosages. The obtained kinetic parameters may be used to estimate ß-cyclocitral dosage and contact time required for the control of cyanobacteria and diatoms in water bodies.

Levels of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and trace metals in the blood of nonoccupationally exposed residents living in the vicinity of a municipal solid waste incinerator and electric arc furnace.

This study examines levels of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and trace metals in the blood of the nonoccupationally exposed residents living in the vicinity of municipal solid waste incinerators (MSWIs) and electric arc furnaces (EAFs). The analysis found that older females had higher concentrations of PCDD/Fs and older males had higher body mass index (BMI) values and higher concentrations of PCDD/Fs. Moreover, sex appeared to affect the levels of PCDD/Fs because, overall, females showed higher levels of PCDD/Fs. The results of a principal component analysis indicated that the characteristics of the blood were more similar to the characteristics of the stack flux gas in MSWIs than those in EAFs. When sex, age, and BMI values were taken into consideration, none of the factors appeared to significantly affect PCDD/F and trace metal blood levels. However, when participants were divided into eight categories and analyzed, it was found that sex was the most important factor affecting levels of trace metals in blood and that males had higher concentrations of Pb, Al, Cd, and Cu.

In situ measurement of odor compound production by benthic cyanobacteria.

A simple technique was developed to make in situ measurements of emission rates of two common odorants, 2-MIB and geosmin, and was validated with different natural communities of benthic cyanobacterial mats in Hope Valley Reservoir (HVR), South Australia, and Kin-Men Water Treatment Plant (TLR-WTP), Taiwan. A pair of parallel columns was used to differentiate between emission and loss rates caused by biodegradation, volatilization, and other mechanisms. Experimental results indicated that the loss rates followed a first-order relationship for all cases tested, with biodegradation and volatilization being the key mechanisms. The loss rates were comparable to those reported in the literature for biodegradation and those calculated from two-film theory for volatilization. After accounting for the loss rates, the net emission of geosmin and 2-MIB was estimated from experimental data. Odorant emission rates on the basis of column surface area, cyanobacterial cell number, and chlorophyll a (chl-a) were 4.2-4.4 ng h(-1) cm(-2), 1.0-5.5 x 10(-6) ng h(-1) cell(-1), and 3.2-3.5 ng h(-1)microg-chl(-1), respectively for 2-MIB released from benthic mats in TLR-WTP, and, 18-190 ng h(-1) cm(-2), 0.053-1.8 x 10(-3) ng h(-1) cell(-1), and 48-435 ng h(-1)microg-chl(-1) respectively for geosmin from benthic mats in HVR. The method developed provides a simple means to estimate the emission rates of odorants and possibly other algal metabolites from benthic cyanobacterial mats.

[Malonato(2-)-κO,O']bis-(1,10-phenanthroline-κN,N')zinc(II) penta-hydrate.

In the title complex, [Zn(C(3)H(2)O(4))(C(12)H(8)N(2))(2)]·5H(2)O, the Zn(II) cation displays a distorted octa-hedral geometry, being coordinated by four N atoms from two 1,10-phenanthroline ligands and two O atoms from different carboxyl-ate groups of the chelating malonate dianion. In the crystal, the complexes are linked into a three-dimensional supra-molecular network by both O-H⋯O hydrogen-bonding inter-actions between water mol-ecules and the uncoordinated carboxyl-ate O atoms of neighboring mol-ecules, and aromatic π-π stacking inter-actions between neighboring phenanthroline rings with centroid-centroid distances of 3.4654 (17) and 3.697 (2) Å.

pH- and DNA-induced dual molecular light switches based on a novel ruthenium(II) complex.

A novel Ru(II) complex, [Ru(bpy)(2)(btppz)]Cl(2), where bpy=2,2'-bipyridine and btppz=benzo[h]tripyrido[3,2-a:2',3'-c:2'',3''-j]phenazine, has been synthesized and characterized. The pH effects on UV-visible (UV-vis) absorption and emission spectra of the complex have been studied and ground- and excited-state ionization constants of the complex have been derived. The calf thymus DNA (ct-DNA) binding properties of the complex were investigated with UV-vis absorption and luminescence spectrophotometric titrations, steady-state emission quenching by [Fe(CN)(6)](4-), DNA competitive binding with ethidium bromide, DNA melting experiments, reverse salt titrations and viscosity measurements. The complex was demonstrated to act as dual molecular switches: pH-induced "on-off" emission switch with an on-off intensity ratio of approximately 54 which is favorably compared with those reported for structurally analogous Ru(II) complexes, and a DNA molecular light switch with a luminescence enhancement factor of 22 as it intercalatively bound to the DNA.

Dynein light chain LC8 regulates syntaphilin-mediated mitochondrial docking in axons.

Mitochondria in the cell bodies of neurons are transported down neuronal processes in response to changes in local energy and metabolic states. Because of their extreme polarity, neurons require specialized mechanisms to regulate mitochondrial transport and retention in axons. Our previous studies using syntaphilin (snph) knock-out mice provided evidence that SNPH targets to axonal mitochondria and controls their mobility through its static interaction with microtubules (MTs). However, the mechanisms regulating SNPH-mediated mitochondrial docking remain elusive. Here, we report an unexpected role for dynein light chain LC8. Using proteomic biochemical and cell biological assays combined with time-lapse imaging in live snph wild-type and mutant neurons, we reveal that LC8 regulates axonal mitochondrial mobility by binding to SNPH, thus enhancing the SNPH-MT docking interaction. Using mutagenesis assays, we mapped a seven-residue LC8-binding motif. Through this specific interaction, SNPH recruits LC8 to axonal mitochondria; such colocalization is abolished when neurons express SNPH mutants lacking the LC8-binding motif. Transient LC8 expression reduces mitochondrial mobility in snph (+/+) but not (-/-) neurons, suggesting that the observed effect of LC8 depends on the SNPH-mediated docking mechanism. In contrast, deleting the LC8-binding motif impairs the ability of SNPH to immobilize axonal mitochondria. Furthermore, circular dichroism spectrum analysis shows that LC8 stabilizes an alpha-helical coiled-coil within the MT-binding domain of SNPH against thermal unfolding. Thus, our study provides new mechanistic insights into controlling mitochondrial mobility through a dynamic interaction between the mitochondrial docking receptor and axonal cytoskeleton.

Combined fluorescence and electrochemical investigation on the binding interaction between organic acid and human serum albumin.

Human serum albumin (HSA) is a plasma protein responsible for the binding and transport of fatty acids and a variety of exogenous chemicals such as drugs and environmental pollutants. Such binding plays a crucial role in determining the ADME (absorption, distribution, metabolism, and excretion) and bioavailability of the pollutants. The binding interaction between HSA and acetic acid (C2), octanoic acid (C8) and dodecanoic acid (C12) has been investigated by the combination of site-specific fluorescent probe, tryptophan intrinsic fluorescence and tyrosine electrochemistry. For the study of the fatty acid interaction with the two drug-binding sites on HSA, two fluorescent probes, dansylamide and dansyl-L-proline were employed in the displacement measurements. Intrinsic fluorescence of tryptophan in HSA was monitored upon addition of the fatty acids into HSA. Electrocatalyzed response of the tyrosine residues in HSA by a redox mediator was used to investigate the binding interaction. Qualitatively, observations from these three approaches were very similar. HSA did not show any change in the fluorescence and electrochemical experiments after mixing with C2, suggesting there is no significant interaction with the short-chain fatty acid. For C8, the measured signal dropped in a single-exponential mode, indicating an independent and non-cooperative binding. The calculated association constant and binding ratio were 3.1 x 10(6) L/mol and 1 with drug binding Site I, 1.1 x 10(7) L/mol and 1 with Site II, and 7.0 x 10(4) L/mol and 4 with the tryptophan site, respectively. The measurements with C12 displayed multiple phases of fluorescence change, suggesting cooperativity and allosteric effect of the C12 binding. These results correlate well with those obtained by the established methods, and validate the new approach as a viable tool to study the interactions of environmental pollutants with biological molecules.

Fluorescence study on site-specific binding of perfluoroalkyl acids to human serum albumin.

Binding of five perfluoroalkyl acids with human serum albumin (HSA) was investigated by site-specific fluorescence. Intrinsic fluorescence of tryptophan-214 in HSA was monitored upon addition of the chemicals. Although perfluorobutyl acid (PFBA) and perfluorobutane sulfonate (PFBS) did not cause fluorescence change, perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), and perfluorododecanoic acid (PFDoA) induced fluorescence quenching, from which binding constant of 2.7 x 10(5) M(-1) for PFOA and 2.2 x 10(4) M(-1) for PFOS was calculated. Two fluorescent probes, dansylamide (DA) and dansyl-L: -proline (DP), were employed in fluorescence displacement measurements to study the interaction at two Sudlow's binding sites. At Site I, both PFBA and PFBS displaced DA with binding constants of 1.0 x 10(6) M(-1) and 2.2 x 10(6) M(-1). At Site II, PFBS and PFDoA displaced DP with binding constants of 6.5 x 10(6) M(-1) and 1.2 x 10(6) M(-1), whereas PFBA did not bind. The data were compared with fatty acids to evaluate the potential toxicological effect of these environmental chemicals.