Myosin VI is the only known reverse-direction myosin motor. It has an unprecedented means of amplifying movements within the motor involving rearrangements of the converter subdomain at the C-terminus of the motor and an unusual lever arm projecting from the converter. While the average step size of a myosin VI dimer is 30–36nm, the step size is highly variable, presenting a challenge to the lever arm mechanism by which all myosins are thought to move. Herein we present new structures of myosin VI that reveal regions of compliance that allow an uncoupling of the lead head when movement is modeled on actin. The location of the compliance restricts the possible actin binding sites and predicts the observed stepping behavior. The model reveals that myosin VI, unlike plus-end directed myosins, does not use a pure lever arm mechanism, but instead steps with a mechanism analogous to the kinesin neck-linker uncoupling model.
HIV and AIDS incidence in China is high among men who have sex with men (MSM) and ours was one of few studies in China to evaluate the role of HIV risk reduction counseling and testing. Respondent-driven sampling (RDS) was used to recruit 430 MSM. Participants were followed up at 6, 12 and 18 months to evaluate behavioral changes after counseling to reduce risk behaviors. At baseline, HIV prevalence was 4.7%, whereas HIV incidence was 5.2 per 100 person-years. The incidence was 3.8 during six to 12 months, and 1.1 during 12 to 18 months. During the study period, the reported unprotected anal intercourse (UAI) significantly decreased from 60.9% to 42.9%. The proportion of participants who had one or no partner significantly increased from 40.9% to 48.0%. The study also found that some risk behaviors decreased between baseline and 12 months, followed by a slight increase between 12 and 18 months. Reductions in UAI can be achieved through counseling and testing, but may wane over time. Future programs should consider HIV risk-reduction counseling and testing for interventions in MSM in China.
Objective. To assess the effects of bariatric surgery versus medical therapy for type 2 diabetes mellitus. Methods. The Cochrane library, PubMed, Embase, Chinese biomedical literature database, and Wanfang database up to February 2012 were searched. The literature searches strategies contained terms (“diabetes∗”, “surg∗”, and “medic∗” were used), combined with the medical subject headings. Randomized controlled trails (RCTs) of frequently used bariatric surgery for obese patients with type 2 diabetes were included. Study selection, data extraction, quality assessment, and data analyses were performed according to the Cochrane standards. Results. Three randomized controlled trials (RCTs) involving 170 patients in the bariatric surgery groups and 100 patients in the medical therapy group were selected. Compared with medical therapy, bariatric surgery for type 2 diabetes can significantly decrease the levels of HbA1c, FBG, weight, triglycerides, and the dose of hypoglycemic, antihypertensive, and lipid-lowering medicine, while increasing the rate of diabetes remission (RR = 9.74, 95%CI, (1.36, 69.66)) and the levels of high-density lipoprotein. However, there are no statistical differences in serious adverse events between the surgical and medical groups (RR = 1.23, 95%CI, (0.80, 1.87)). Conclusions. Surgical procedures were more likely to help patients achieve benefits than medical therapy alone. Further intensive RCTs of high-quality, multiple centers and long-term followup should be carried out to provide more reliable evidence.
Amitriptyline (AMI) is tricyclic antidepressant that has been widely used to manage various chronic pains such as migraines. Its efficacy is attributed to its blockade of voltage-gated sodium channels (VGSCs). However, the effects of AMI on the tetrodotoxin-resistant (TTX-r) sodium channel Nav1.9 currents have been unclear to present.
Using a whole-cell patch clamp technique, this study showed that AMI efficiently inhibited Nav1.9 currents in a concentration-dependent manner and had an IC50 of 15.16 μM in acute isolated trigeminal ganglion (TG) neurons of the rats. 10 μM AMI significantly shifted the steady-state inactivation of Nav1.9 channels in the hyperpolarizing direction without affecting voltage-dependent activation. Surprisingly, neither 10 nor 50 μM AMI caused a use-dependent blockade of Nav1.9 currents elicited by 60 pulses at 1 Hz.
These data suggest that AMI is a state-selective blocker of Nav1.9 channels in rat nociceptive trigeminal neurons, which likely contributes to the efficacy of AMI in treating various pains, including migraines.
Amitriptyline; Nav1.9; Patch clamp; Trigeminal ganglion; Pain
O-Linked β-N-acetylglucosaminyl transferase (OGT) plays an important role in the glycosylation of proteins, which is involved in various cellular events. In human, three isoforms of OGT (short OGT [sOGT]; mitochondrial OGT [mOGT]; and nucleocytoplasmic OGT [ncOGT]) share the same catalytic domain, implying that they might adopt a similar catalytic mechanism, including sugar donor recognition. In this work, the sugar-nucleotide tolerance of sOGT was investigated. Among a series of uridine 5′-diphosphate-N-acetylglucosamine (UDP-GlcNAc) analogs tested using the casein kinase II (CKII) peptide as the sugar acceptor, four compounds could be used by sOGT, including UDP-6-deoxy-GlcNAc, UDP-GlcNPr, UDP-6-deoxy-GalNAc and UDP-4-deoxy-GlcNAc. Determined values of Km showed that the substitution of the N-acyl group, deoxy modification of C6/C4-OH or epimerization of C4-OH of the GlcNAc in UDP-GlcNAc decreased its affinity to sOGT. A molecular docking study combined with site-directed mutagenesis indicated that the backbone carbonyl oxygen of Leu653 and the hydroxyl group of Thr560 in sOGT contributed to the recognition of the sugar moiety via hydrogen bonds. The close vicinity between Met501 and the N-acyl group of GlcNPr, as well as the hydrophobic environment near Met501, were responsible for the selective binding of UDP-GlcNPr. These findings illustrate the interaction of OGT and sugar nucleotide donor, providing insights into the OGT catalytic mechanism.
The present study aimed to investigate the correlation between the expression of vascular endothelial growth factor (VEGF) and its receptors, the Flt-1 and KDR proteins, with clinical pathology and microvessel density (MVD) in ovarian cancer tissue. The protein expression levels of VEGF and its receptors, Flt-1 and KDR/Flk-1, were detected in 48 cases of ovarian cancer using the streptavidin-biotin complex (SABC) immunohistochemical method, and tumor MVD was evaluated using F8 factor (FVIII-RA). The expression of the VEGF, Flt-1 and KDR proteins was not significantly associated with the pathological type, extent of differentiation or clinical stage of ovarian cancer. However, the co-expression of VEGF and Flt-1 was markedly correlated with differentiation and clinical stage (P<0.01). The co-expression levels of VEGF and receptor Flt-1 in malignant neoplasms with lymph node metastasis was significantly higher compared with malignant neoplasms without lymph node metastasis (P<0.05). The expression level of KDR in patients with hepatic metastasis was significantly higher compared with patients without hepatic metastasis (P<0.05). The co-expression level of VEGF and KDR in patients with hepatic metastasis was significantly higher compared with patients without hepatic metastasis (P<0.05) and the Flt-1 expression level in patients with ascites <1,000 ml was significantly lower than that in patients with ascites ≥1000 ml (P<0.05). The mean MVD of VEGF- and KDR-positive patients was significantly higher compared with VEGF- and KDR-negative patients (P<0.05). The expression of VEGF and its receptors is involved in the malignant transformation of ovarian tumors, tumor progression and metastasis, as well as ascites formation and angiogenesis.
vascular endothelial growth factor; Flt-1 receptor; KDR receptor; oophoroma; ascites
Lung cancers express the cholinergic autocrine loop, which facilitates the progression of cancer cells. The antagonists of mAChRs have been demonstrated to depress the growth of small cell lung cancers (SCLCs). In this study we intended to investigate the growth inhibitory effect of R2HBJJ, a novel muscarinic antagonist, on non-small cell lung cancer (NSCLC) cells and the possible mechanisms. The competitive binding assay revealed that R2HBJJ had a high affinity to M3 and M1 AChRs. R2HBJJ presented a strong anticholinergic activity on carbachol-induced contraction of guinea-pig trachea. R2HBJJ markedly suppressed the growth of NSCLC cells, such as H1299, H460 and H157. In H1299 cells, both R2HBJJ and its leading compound R2-PHC displayed significant anti-proliferative activity as M3 receptor antagonist darifenacin. Exogenous replenish of ACh could attenuate R2HBJJ-induced growth inhibition. Silencing M3 receptor or ChAT by specific-siRNAs resulted in a growth inhibition of 55.5% and 37.9% on H1299 cells 96 h post transfection, respectively. Further studies revealed that treatment with R2HBJJ arrested the cell cycle in G0/G1 by down-regulation of cyclin D1-CDK4/6-Rb. Therefore, the current study reveals that NSCLC cells express an autocrine and paracrine cholinergic system which stimulates the growth of NSCLC cells. R2HBJJ, as a novel mAChRs antagonist, can block the local cholinergic loop by antagonizing predominantly M3 receptors and inhibit NSCLC cell growth, which suggest that M3 receptor antagonist might be a potential chemotherapeutic regimen for NSCLC.
MTDH(metadherin), an important oncogene that is widely overexpressed in various cancers, is a potential biomarker of tumor malignancy. Variants in MTDH have been associated with susceptibility to breast cancer. However, no studies assessing MTDH gene polymorphisms and their potential relationship to ovarian cancer susceptibility have been reported. Thus, we investigated the association of MTDH (−470G>A) polymorphism with ovarian cancer development in 145 ovarian cancer patients and 254 matched control subjects, using sequence analysis. We found that the MTDH (−470G>A) polymorphism was statistically correlated with ovarian cancer risk (under the additive genetic model, GG vs. GA vs AA, P = 0.042). Compared with genotypes containing the G allele (GG and GA), the AA genotype may decrease the risk of ovarian cancer (P = 0.0198, OR = 0.33, 95% CI [0.12∼0.78]). Compared with the G allele, the A allele is protective against ovarian cancer risk (P = 0.01756, OR = 0.66, 95% CI [0.46∼0.93]). Furthermore, a statistically significant association between the GG and GA+AA genotypes and the clinical stage was observed (P = 0.038). These data suggest that MTDH (−470G>A) could be a useful molecular marker for assessing ovarian cancer risk and for predicting ovarian cancer patient prognosis.
The inflammatory response has been associated with the pathogenesis of Alzheimer’s disease (AD). The purpose of this study is to determine whether the rs1143627 polymorphism of the interleukin-1 beta (IL-1β) gene moderates functional magnetic resonance imaging (fMRI)-measured brain regional activity in amnestic mild cognitive impairment (aMCI).
Eighty older participants (47 with aMCI and 33 healthy controls) were recruited for this study. All of the participants were genotyped for variant rs1143627 in the IL1B gene and were scanned using resting-state fMRI. Brain activity was assessed by amplitude of low-frequency fluctuation (ALFF).
aMCI patients had abnormal ALFF in many brain regions, including decreases in the inferior frontal gyrus, the superior temporal lobe and the middle temporal lobe, and increases in the occipital cortex (calcarine), parietal cortex (Pcu) and cerebellar cortex. The regions associated with an interaction of group X genotypes of rs1143627 C/T were the parietal cortex (left Pcu), frontal cortex (left superior, middle, and medial gyrus, right anterior cingulum), occipital cortex (left middle lobe, left cuneus) and the bilateral posterior lobes of the cerebellum. Regarding the behavioral significance, there were significant correlations between ALFF in different regions of the brain and with the cognitive scores of each genotype group.
The present study provided evidence that aMCI patients had abnormal ALFF in many brain regions. Specifically, the rs1143627 C/T polymorphism of the IL1B gene may modulate regional spontaneous brain activity in aMCI patients.
Amnestic mild cognitive impairment; Functional magnetic resonance imaging; Amplitude of low-frequency fluctuation; Interleukin-1 beta; Cognition
Secreted protein acidic and rich in cysteine (SPARC), a calcium-binding matricellular glycoprotein, is implicated in the progressions of some cancers. However, no information has been available to date regarding the function of SPARC in cervical cancer cell growth and metastasis.
In this study, we isolated and established high invasive subclones and low invasive subclones from human cervical cancer cell lines HeLa and SiHa by the limited dilution method. Real-time q-RT-PCR, Western Blot and ICC were performed to investigate SPARC mRNA and protein expressions in high invasive subclones and low invasive subclones. Then lentivirus vector with SPARC shRNA was constructed and infected the highly invasive subclones. Real-time q-RT-PCR, Western Blot and ICC were also performed to investigate the changes of SPARC expression after viral infection. In functional assays, effects of SPARC knockdown on the biological behaviors of cervical cancer cells were investigated. The mechanisms of SPARC in cervical cancer proliferation, apoptosis and invasion were also researched.
SPARC was over-expressed in the highly invasive subclones compared with the low invasive subclones. Knockdown of SPARC significantly suppressed cervical cancer cell proliferation, and induced cell cycle arrest at the G1/G0 phase through the p53/p21 pathway, also caused cell apoptosis accompanied by the decreased ratio of Bcl-2/Bax, and inhibited cell invasion and metastasis accompanied by down-regulated MMP2 and MMP9 expressions and up-regulated E-cadherin expression.
SPARC is related to the invasive phenotype of cervical cancer cells. Knockdown of SPARC significantly suppresses cervical cancer cell proliferation, induces cell apoptosis and inhibits cell invasion and metastasis. SPARC as a promoter improves cervical cancer cell growth and metastasis.
SPARC; Cervical cancer; Proliferation; Apoptosis; Metastasis
To investigate the relationship between amnestic mild cognitive impairment (aMCI) and candidate gene polymorphisms in a Chinese population, 116 aMCI patients and 93 normal controls were recruited. Multi-dimensional neuropsychological tests were used to extensively assess the cognitive functions of the subjects. MassARRAY and iPLEX systems were used to measure candidate single nucleotide polymorohisms (SNPs) and analyse allelic, genotypic or haplotypic distributions. The scores of the neuropsychological tests were significantly lower for the aMCI patients than for the normal controls. The distributions of SNPs relating to the amyloid cascade hypothesis (TOMM40 rs157581 G and TOMM40 rs2075650 G), to the cholesterol metabolism hypothesis (ApoE rs429358 C, LDLR rs11668477 G and CH25H rs7091822 T and PLAU rs2227564 CT) and to the tau hypothesis (MAPT/STH rs242562 GG) in aMCI were significantly different than those in normal controls. Interactions were also found in aMCI amongst SNPs in LDLR rs11668477, PLAU rs2227564, and TOMM40 rs157581, between SNPs in TOMM40 rs157580 and BACE2 rs9975138. The study suggests that aMCI is characterised by memory impairment and associated with SNPs in three systems relating to the pathogenesis of AD-those of the amyloid cascade, tau and cholesterol metabolism pathways. Interactions were also observed between genes in the amyloid pathway and between the amyloid and cholesterol pathways.
Ribonucleic acid interference (RNAi) based on microRNA (miRNA) context may provide an efficient and safe therapeutic knockdown effect and can be driven by ribonucleic acid polymerase II (RNAP II). In this study, we designed and synthesized miR155-based artificial miRNAs against heparanase (HPSE) constructed with BLOCK-iT™ Pol II miR RNAi Expression Vector Kit. The expression levels of HPSE declined significantly in both the mRNA and protein levels in HPSE-miRNA transfected melanoma cells that exhibited reduction of adhesion, migration, and invasion ability in vitro and in vivo. We also observed that HPSE miRNA could inhibit the expressions of chemokines of interleukin-8 (IL8) and chemokine (C-X-C motif) ligand 1 (CXCL1), at both the transcriptional and translational levels. Further study on its probable mechanism declared that down-regulation of IL8 and CXCL1 by HPSE-miRNA may be correlated with reduced growth-factor simulated mitogen-activated kinase (MAPK) phosphorylation including p38 MAPK, c-Jun N-terminal kinase (JNK) and extracellular-signal-regulated kinase (ERK) 1 and 2, which could be rescued by miRNA incompatible mutated HPSE cDNA. In conclusion, we demonstrated that artificial miRNAs against HPSE might serve as an alterative mean of therapy to low HPSE expression and to block the adhesion, invasion, and metastasis of melanoma cells. Furthermore, miRNA-based RNAi was also a powerful tool for gene function study.
Loss of estrogen receptor α (ERα) expression and gain of TWIST (TWIST1) expression in breast tumors correlate with increased disease recurrence and metastasis and poor disease-free survival. However, the molecular and functional regulatory relationship between TWIST and ERα are unclear. In this study, we found TWIST was associated with a chromatin region in intron 7 of the human ESR1 gene coding for ERα. This association of TWIST efficiently recruited the nucleosome remodeling and deacetylase (NuRD) repressor complex to this region, which subsequently decreased histone H3K9 acetylation, increased histone H3K9 methylation and repressed ESR1 expression in breast cancer cells. In agreement with these molecular events, TWIST expression was inversely correlated with ERα expression in both breast cancer cell lines and human breast ductal carcinomas. Forced expression of TWIST in TWIST-negative and ERα-positive breast cancer cells such as T47D and MCF-7 cells reduced ERα expression, while knockdown of TWIST in TWIST-positive and ERα-negative breast cancer cells such as MDA-MB-435 and 4T1 cells increased ERα expression. Furthermore, inhibition of histone deacetylase (HDAC) activity including the one in NuRD complex significantly increased ERα expression in MDA-MB-435 and 4T1 cells. HDAC inhibition together with TWIST knockdown did not further increase ERα expression in 4T1 and MDA-MB-435 cells. These results demonstrate that TWIST/NuRD represses ERα expression in breast cancer cells. Therefore, TWIST may serve as a potential molecular target for converting ERα-negative breast cancers to ERα-positive breast cancers, allowing these cancers to restore their sensitivity to endocrine therapy with selective ERα antagonists such as tamoxifen and raloxifene.
TWIST; ERα; NuRD complex; gene repression; breast cancer
The distal-less homeobox gene 4 (DLX4) is a member of the DLX family of homeobox genes. Although absent from most normal adult tissues, DLX4 is widely expressed in leukemia, lung, breast, ovarian and prostate cancers. However the molecular targets, mechanisms and pathways that mediate the role of DLX4 in tumor metastasis are poorly understood. In this study, we found that DLX4 induces cancer cells to undergo epithelial to mesenchymal transition (EMT) through TWIST. Overexpression of DLX4 increased expression of TWIST expression in cancer cell lines, resulting in increased migratory and invasive capacity. Likewise, knocking down expression of DLX4 decreased TWIST expression and the migration ability of cancer cell lines. DLX4 bound to regulatory regions of the TWIST gene. Both western blotting and immunohistochemistry staining showed that the expression of DLX4 and TWIST are correlated in most of breast tumors. Taken together, these data from both cell models and tumor tissues demonstrate that DLX4 not only upregulates TWIST expression but also induces EMT and tumor metastasis. Altogether, we propose a new pathway in which DLX4 drives expression of TWIST to promote EMT, cancer migration, invasion and metastasis.
DLX4; TWIST; E-Cadherin; breast cancer; metastasis
Cardiac fibroblasts (CFs) are the primary cell type responsible for cardiac fibrosis during pathological myocardial remodeling. Several studies have illustrated that pirfenidone (5-methyl-1-phenyl-2-[1H]-pyridone) attenuates cardiac fibrosis in different animal models. However, the effects of pirfenidone on cardiac fibroblast behavior have not been examined. In this study, we investigated whether pirfenidone directly modulates cardiac fibroblast behavior that is important in myocardial remodeling such as proliferation, myofibroblast differentiation, migration and cytokine secretion. Fibroblasts were isolated from neonatal rat hearts and bioassays were performed to determine the effects of pirfenidone on fibroblast function. We demonstrated that treatment of CFs with pirfenidone resulted in decreased proliferation, and attenuated fibroblast α-smooth muscle actin expression and collagen contractility. Boyden chamber assay illustrated that pirfenidone inhibited fibroblast migration ability, probably by decreasing the ratio of matrix metalloproteinase-9 to tissue inhibitor of metalloproteinase-1. Furthermore, pirfenidone attenuated the synthesis and secretion of transforming growth factor-β1 but elevated that of interleukin-10. These direct and pleiotropic effects of pirfenidone on cardiac fibroblasts point to its potential use in the treatment of adverse myocardial remodeling.
The etiology of motor neuron degeneration in amyotrophic lateral sclerosis (ALS) remains to be better understood. Based on the studies from ALS patients and transgenic animal models, it is believed that ALS is likely to be a multifactorial and multisystem disease. Many mechanisms have been postulated to be involved in the pathology of ALS, such as oxidative stress, glutamate excitotoxicity, mitochondrial damage, defective axonal transport, glia cell pathology and aberrant RNA metabolism. Mitochondria, which play crucial roles in excitotoxicity, apoptosis and cell survival, have shown to be an early target in ALS pathogenesis and contribute to the disease progression. Morphological and functional defects in mitochondria were found in both human patients and ALS mice overexpressing mutant SOD1. Mutant SOD1 was found to be preferentially associated with mitochondria and subsequently impair mitochondrial function. Recent studies suggest that axonal transport of mitochondria along microtubules and mitochondrial dynamics may also be disrupted in ALS. These results also illustrate the critical importance of maintaining proper mitochondrial function in axons and neuromuscular junctions, supporting the emerging “dying-back” axonopathy model of ALS. In this review, we will discuss how mitochondrial dysfunction has been linked to the ALS variants of SOD1 and the mechanisms by which mitochondrial damage contributes to the disease etiology.
amyotrophic lateral sclerosis; mutant SOD1; mitochondrial function; axonal transport; mitochondrial dynamics
A cross-sectional study using the snowball sampling method was conducted in May 2008 to investigate human immunodeficiency virus (HIV) infection status and related high risk factors among men who have sex with men (MSM) in Suzhou city of Jiangsu province. The researchers carried out a face-to-face questionnaire interview among MSM, and collected their blood samples to test for HIV and other sexually transmitted diseases (STDs). Among the 280 respondents, 91.1% had homosexual acts in the past 6 months and 87.5% had multiple homosexual partners; 46.4% had heterosexual sex in the past 6 months and 33.1% had multiple heterosexual partners. The rate of continued condom use was 44.3% in homosexual sex in the past 6 months, while the rate in heterosexual sex was 33.9%. Laboratory test results showed that the prevalences of HIV and syphilis were 7.1% (20/280) and 15.0% (42/280), respectively, but no HCV-positive person was found. In the multivariate logistic regression model, subjects with a monthly income of more than RMB ¥ 1,000 (OR=4.83,95% CI=1.44-16.22), subjects who often went to bars for sexual partners (OR=2.25, 95%CI=1.21-4.20), and subjects who had more than one sexual partner in the past 6 months (OR=0.49, 95%CI=0.25-0.97) and had sex with fixed sexual partners in the past 6 months (OR=0.42, 95%CI=0.25-0.75) were significantly associated with the rate of continued condom use in homosexual sex in the past 6 months. Unprotected sex and multiple sexual partners were more common among MSM in Suzhou city; furthermore, the prevalences of HIV infection and syphilis were relatively high. HIV preventive measures should be designed to address these risk factors and control the spread of HIV among MSM.
men who have sex with men; knowledge, behavior; HIV infection; risk factor
Quantitative proteomics is challenging and various stable isotope based approaches have been developed to meet the challenge.. Hereby we describe a simple, efficient, reliable and inexpensive method named RABA (reductive alkylation by acetone) to introduce stable isotopes to peptides for quantitative analysis. The RABA method leads to alkylation of N-terminal and lysine amino groups with isopropyl moiety. Using unlabeled (d0) and deuterium labeled (d6) acetone, a 6 Da mass split is introduced to each isopropyl modification between the light and heavy isotope labeled peptides, which is ideally suited for quantitative analysis. The reaction specificity, stoichoimetry, labeling efficiency and linear range of the RABA method has been thoroughly evaluated in this study using standard peptides, tryptic digest of proteins as well as human cell lysate. Reliable quantitative results have been consistently obtained in all experiments. We also applied the RABA method to quantitative analysis of proteins in spinal cords of transgenic mouse models of amyotrophic lateral sclerosis. Highly homologous proteins (transgenic human SOD1 and endogenous mouse SOD1) were distinguished and quantified using the method developed in this study. In addition, the quantitative results using the RABA approach were independently validated by Western blot.
A novel approach to prepare homogeneous PbS nanoparticles by phase-transfer method was developed. The preparatory conditions were studied in detail, and the nanoparticles were characterized by transmission electron microscopy (TEM) and UV-vis spectroscopy. Then a novel lead ion-selective electrode of polyvinyl chloride (PVC) membrane based on these lead sulfide nanoparticles was prepared, and the optimum ratio of components in the membrane was determined. The results indicated that the sensor exhibited a wide concentration range of 1.0×10−5 to 1.0×10−2 mol.L−1. The response time of the electrode was about 10 s, and the optimal pH in which the electrode could be used was from 3.0 to 7.0. Selectivity coefficients indicated that the electrode was selective to the primary ion over the interfering ion. The electrode can be used for at least 3 months without any divergence in potential. It was successfully applied to directly determine lead ions in solution and used as an indicator electrode in potentiometric titration of lead ions with EDTA.
Ion-selective electrode; lead sensors; PbS nanoparticles; phase-transfer method; PVC membrane