[Transport and Model Calculation of Microplastics Under the Influence of Ionic Type, Strength, and Iron Oxide].

Microplastics (MPs) in soil have attracted extensive attention as an emerging pollutant, and the transport of MPs is affected by their own physical and chemical properties, the chemical composition of soil solutions, and soil minerals. However, in the presence of oxides, the underlying mechanism for the transport of MPs in different ionic types and ionic strengths is still not fully understood. In this study, the effects of ionic type, ionic strength, and iron oxide on the transport of polystyrene microplastics (PSMPs) with different functional groups were investigated through stability experiments and transport experiments. The colloid transport model, CD-MUSIC model, and DLVO theory were used to explore the transport mechanism. The results showed that normalized concentrations (c/c0) of PSMPs were 0.99 in the NaH2PO4 background and 0.94 in the CaCl2 background, respectively, which indicated that the strongest stability of PSMPs was observed in the former and the weakest in the latter. Different ionic types had different effects on the transport of PSMPs. For the cations Na+ and Ca2+, Ca2+ strongly inhibited PSMPs transport in pure quartz sand because of the bridging effect and strong charge neutralization effect; the recovery rate of the PSMPs in the effluent was (43.83±1.71)%, and a first-order retention coefficient on the second kinetic Site-2 (k2a) was 1.54 min-1. The presence of iron oxide enhanced the inhibition, the recovery rate of the PSMPs in the effluent decreased to (6.04±0.40)%, and k2a increased to 5.33 min-1. For the anions Cl- and PO43-, the transport of PSMPs in pure quartz sand was dominated by surface electronegativity of PSMPs, and PSMPs exhibited lower electronegativity under Cl- background and thus showed higher recovery[(92.95±0.63)%] and lower k2a (0.19 min-1). However, in the presence of iron oxides, the Zeta potential of the quartz sand surface was the controlling factor for PSMPs transport. According to results of the CD-MUSIC model, PO43- could be easily adsorbed on the iron oxide surface to form innersphere complexes, which reduced the surface electronegativity of the iron-loaded quartz sand and enhanced the transport of PSMPs, higher recovery[(76.22±1.39)%], and lower k2a (0.66 min-1). Moreover, the species of the formed innersphere complex was controlled by the PO43- concentration, and different species of innersphere complexes had distinct negative surface charges. Higher surface electronegativity of the iron-loaded quartz sand was observed under higher PO43- concentration, which was not conducive to the transport of PSMPs. Further, the transport ability of PSMPs decreased with the increase in ionic strength. Finally, the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory was used to calculate the variation in the primary barrier between PSMPs and the collector under the conducted experimental conditions, which helped better elucidate the transport behavior of PSMPs. The variation in the primary barrier was consistent with the transport ability of PSMPs, and a higher primary barrier indicated a larger repulsion between PSMPs and the collector, which was in favor of PSMPs transport.

[Effects of pH, Calcium, and Phosphate on the Solubility of Arsenic in Paddy Soil Based on Surface Complexation Modeling].

This study aimed to obtain a better understanding on the environmental behavior of As in paddy soil and to reveal the influence mechanisms of different environmental factors on the availability of As in the soil solution. The effects of pH, calcium, and phosphate on the solubility and speciation distribution of As in the paddy soil collected from Zhuzhou of Hunan province were studied by combining the adsorption experiments with the NOM-CD model. The results showed that the minimum concentration of soluble As in the soil was at approximately a pH of 6.0, which was mainly affected by both electrical interactions and site competition between Ca2+, PO43-, As(Ⅲ), and As(Ⅴ). The adsorption of As onto soil particles could be increased by an increase in Ca2+ in the soil system, leading to the decrease in soluble As concentration. This effect became significant at a higher pH, because adsorbed Ca2+ increased the positive charge on (hydr)oxide surfaces. With phosphate addition, the reduction in As(Ⅴ) in the soil was inhibited at pH<5.5, whereas it was promoted at pH>5.5. Moreover, the concentration of soluble As(Ⅲ) and As(Ⅴ) in the soil solution was dramatically increased with the addition of phosphate owing to the competitive adsorption between As and phosphate. At a lower background of Ca2+, there was a higher fraction of As(Ⅲ) in the soil either with or without phosphate addition. This phenomenon might be caused by the higher bioavailability of phosphorus in soil at a lower concentration of Ca2+, which favors the dissimilatory reduction of As or iron (hydr)oxides. The results indicated that the NOM-CD model could predict the influence of pH, calcium, and phosphate on the solubility and speciation distribution of As in paddy soil and reveal its main mechanisms. Therefore, the NOM-CD model would provide the quantitative and scientific method for evaluating the risk of As in soils or other solid-water systems.

[Stability of Ferrihydrite and Goethite Nanoparticles Under Different Environmental Conditions].

Agglomeration and dispersion of nanoparticles control many important environmental processes. In this study, the particle size and zeta potential of ferrihydrite nanoparticles (FHNPs) and goethite nanoparticles (GTNPs) under different pH, ion, and organic matter conditions were measured. These data were used to calculate the Derjaguin-Landau-Verwey-Overbeek (DLVO) interaction energy between nanoparticles to further investigate the stability of two nanoparticles. The results showed that Na+ and Ca2+ promoted FHNPs and GTNPs agglomeration due to their ionic strength. The PO43- with low-concentration (2 mmol·L-1), humic acid and fulvic acid (2 mg·L-1 and 10 mg·L-1) loaded on iron mineral nanoparticles changed their surface charge and further improved the stability of FHNPs and GTNPs at medium and high pH. Although the PO43- with high concentration (10 mmol·L-1) also changed the electrical properties of iron mineral nanoparticles, it had little contribution to the GTNP stability due to its ionic strength. When the zeta potentials of FHNPs or GTNPs were close to 0, the primary barrier and secondary minima were nonexistent simultaneously. The two kinds of nanoparticles irreversibly agglomerated in primary minima. When the primary barrier and secondary minima coexisted, the proportion of reversible aggregation of FHNPs and GTNPs in secondary minima increased. The results provided support for further investigation of the environmental behavior of FHNPs and GTNPs, and iron mineral nanoparticle-facilitated transport of pollutants.

Silencing interleukin 1α underlies a novel inhibitory role of miR-181c-5p in alleviating low-grade inflammation of rats with irritable bowel syndrome.

Irritable bowel syndrome (IBS) is a common disorder of unknown etiology. Studies have found a close relation between IBS and microRNAs (miRNAs), but the study concerning the relationship between IBS and miR-181c-5p in IBS is still blank. Thus, this study aims to explore the role of miR-181c-5p in IBS via interleukin 1α (IL1A). Initially, microarray analysis was used to retrieve the genes related to IBS and to predict miRNAs regulating IL1A gene. IBS model was then established with abdominal withdraw reflection (AWR) and Bristol stool grading in mice measured. Afterwards, the functional role of miR-181c-5p in IBS was determined using the ectopic expression, depletion and reporter assay experiments, as well as miR-181c-5p and IL1A expression detected. Subsequently, expression of tumor necrosis factor-α (TNF-α), interleukin-2 (IL-2), and IL-6 were detected to further determine the effects of miR-181c-5p and IL1A on inflammation in IBS. miR-181c-5p and IL1A might be involved in IBS. miR-181c-5p was found to be decreased while IL1A was increased in IBS rats. In addition, miR-181c-5p could target and inhibit expression of IL1A, and IBS mice exhibited elevated AWR and Bristol stool grading, namely 6 to 7 points (70.4 [38 of 54]). Moreover, with the overexpression of miR-181c-5p or silencing of IL1A, the expression of TNF-α, IL-2, and IL-6 was decreased. Collectively, this study suggested that overexpressed miR-181c-5p could silence IL1A, thus inhibiting low-grade inflammation in IBS rats. miR-181c-5p/IL1A is expected to serve as a novel target for the treatment of IBS.

[Arsenic Adsorption and Its Species on Ferrihydrite and Ferrihydrite Colloid].

Batch experiments were conducted to investigate the adsorption kinetics and adsorption isotherms of As(Ⅲ) and As(Ⅴ) on ferrihydrite and its colloid. A sequential extraction technique and As speciation extraction were used to assess the chemically bound fractions of As and As species in solids, respectively. The kinetic and isotherm data showed that the adsorption was multilevel and readily occurred. The adsorption of As(Ⅲ) and As(Ⅴ) on the ferrihydrite colloid was 194.8 g·kg-1 and 107.3 g·kg-1, respectively, which was higher than that on ferrihydrite (155.2 g·kg-1 and 104.4 g·kg-1). The specifically adsorbed As, amorphous oxide bound As, and crystalline oxide bound As were the major fractions of adsorbed As on ferrihydrite and its colloid. The residual As was absorbed on the ferrihydrite surface instead of on the ferrihydrite colloid. Therefore, As adsorption on ferrihydrite was much stronger than that on ferrihydrite colloid. The ferrihydrite and ferrihydrite colloid could not reduce As(Ⅴ) to As(Ⅲ).

Bioequivalence and pharmacokinetic evaluation of two formulations of risperidone 2 mg : an open-label, single-dose, fasting, randomized-sequence, two-way crossover study in healthy male Chinese volunteers.

BACKGROUND: Risperidone is a benzisoxazole derivate and is effective in the treatment of schizophrenia and other psychiatric illnesses in adults and children. Although there are a few reports in the literature regarding the pharmacokinetic characteristics of risperidone, insufficient data on its pharmacokinetic properties in a Chinese population are available. OBJECTIVE: To meet the requirements for marketing a new generic product, this study was designed to compare the pharmacokinetic properties and bioequivalence of two 2 mg tablet formulations of risperidone: a newly developed generic formulation (test) and a branded formulation (reference) in healthy adult male Chinese volunteers. METHODS: A single-dose, open-label, randomized-sequence, 2 × 2 crossover study was conducted in fasted healthy male Chinese volunteers. Eligible participants were randomly assigned in a 1:1 ratio to receive 1 tablet (2 mg each) of the test formulation (Risperidone tablet; Dr. Reddy's Laboratories Ltd., Hyderabad, India) or the reference formulation (Risperdal(®) tablet; Xian-Janssen Pharmaceutical Ltd., Xi-an, China), followed by a 2-week washout period and subsequent administration of the alternate formulation. The study drugs were administered after a 10-hour overnight fast. Plasma samples were collected over 96 hours. Plasma concentrations of the parent drug, risperidone, and its active metabolite, 9-hydroxy-risperidone, were analyzed by a liquid chromatography-tandem mass spectrometry method. The formulations would be considered bioequivalent if the 90% confidence intervals (CIs) of the natural log-transformed values were within the predetermined 80-125% equivalence range for the maximum plasma drug concentration (Cmax) and the area under the plasma concentration-time curve (AUC), in accordance with guidelines issued by the US Food and Drug Administration. Assessment of tolerability was based on recording of adverse events (AEs), monitoring of vital signs, electrocardiograms, and laboratory tests at baseline and at completion of the study. RESULTS: A total of 24 healthy male Chinese volunteers (mean age 22.9 years [standard deviation (SD) 2.7, range 19.2-27.1]; weight 63.2 kg [SD 7.0, range 52.0-78.0]; and height 171.3 cm [SD 6.1, range 162.0-187.0]) were enrolled, and all completed the study. For the parent drug, risperidone, the 90% CIs of the relative values (test vs. reference) of the Cmax, AUC from time zero to time t (AUCt), and AUC from time zero to infinity (AUC∞) were 97.0-124.0%, 92.7-115.1%, and 92.8-114.2%, respectively. For the active metabolite, 9-hydroxy-risperidone, the values were 104.4-117.7%, 101.0-113.7%, and 100.4-113.4%, respectively. The two formulations met the predetermined criteria for bioequivalence. A total of 73 AEs were observed in 24 subjects during the study. The most common AE was sedation (48 events), followed by nasal reactions (14 events), postural hypotension (3 events), hypertriglyceridemia (2 events), dizziness (4 events), nausea (1 event), and anorexia (1 event). Their severity was as follows: 16 were mild, 57 were moderate, and none were severe. The majority of the AEs were considered to be related (48 events) or probably related (23 events) to the study medication. No clinically significant abnormalities on physical examination, vital sign measurements, or electrocardiographic recordings were reported. No serious AEs were reported. CONCLUSIONS: The data from this study in healthy adult male Chinese subjects suggest that the test formulation met the regulatory criteria for bioequivalence to the reference formulation, on the basis of the rate and extent of absorption. Both formulations were well tolerated.

Relative bioavailability of generic and branded acetylcysteine effervescent tablets: A single-dose, open-label, randomized-sequence, two-period crossover study in fasting healthy Chinese male volunteers.

BACKGROUND: Acetylcysteine may be used as a muco- lytic agent for the treatment of chronic bronchitis, chronic obstructive pulmonary disease, and other pulmonary diseases complicated by the production of viscous mucus. However, little is known of its pharmacokinetic properties when given orally in healthy volunteers, particularly in a Chinese Han population. This study was conducted to provide support for the marketing of a generic product in China. OBJECTIVE: The purpose of this study was to compare the pharmacokinetics and relative bioavailability of a generic test formulation and a branded reference formulation of acetylcysteine in fasting healthy Chinese male volunteers. METHODS: A single-dose, open-label, randomized-sequence, 2-period crossover design with a 7-day washout period between doses was used in this study. Healthy Chinese male nonsmokers aged 18 to 40 years with a body mass index (BMI) of 19 to 25 kg/m(2) were selected. Eligible volunteers were randomly assigned to receive acetylcysteine 600 mg PO as either the test formulation (3 tablets of 200 mg each) or reference formulation (1 tablet of 600 mg) under fasting conditions. A total of 15 serial blood samples were collected over a 24-hour interval, and total plasma acetylcysteine concentrations were analyzed by a validated liquid chromatography-isotopic dilution mass spectrometry method. Pharmacokinetic parameters (C(max), T(max), t(½) AUC(0-t), and AUC(0-∞) were calculated and analyzed statistically. The 2 formulations were considered bioequivalent if the 90% CIs of the log-transformed ratios (test/reference) of C(max) and AUC were within the predetermined bioequivalence ranges (70%-143% for C(max); 80%-125% for AUC), as established by the State Food and Drug Administration of China. Tolerability was determined by vital signs, clinical laboratory tests, 12-lead ECGs, physical examinations, and interviews with the subjects about adverse events (AEs). RESULTS: A total of 24 healthy Chinese Han male volunteers were enrolled in and completed the study (mean [SD] age, 25.0 [2.4] years; height, 173.0 [5.6] cm; weight, 65.9 [6.4] kg; BMI, 22.0 [1.7] kg/m(2)). No formulation, period, or sequence effects were observed. The 90% CIs for the log-transformed C(max), AUC(0-t), and AUC(0-∞) were 89.7% to 103.8%, 86.7% to 101.7%, and 87.7% to 102.4%, respectively, which met the predetermined criteria for assuming bioequivalence. Two subjects (8.3%) experienced 2 mild AEs (increase in total bile acid and prolongation of the QT interval), which were not considered to be related to study drug administration. CONCLUSIONS: This single-dose study of acetylcysteine 600 mg PO found that the 3 tablets of the generic test formulation and 1 tablet of the branded reference formulation met the regulatory criteria for assuming bioequivalence in these fasting healthy Chinese male volunteers. Both formulations were generally well tolerated.

Bioequivalence and pharmacokinetic evaluation of two formulations of glimepiride 2 mg: a single-dose, randomized-sequence, open-label, two-way crossover study in healthy Chinese male volunteers.

BACKGROUND: Glimepiride is an oral sulfonylurea antihyperglycemic agent indicated for the treatment of type 2 diabetes mellitus. Although there are reports in the literature regarding the pharmacokinetic (PK) characteristics of glimepiride, few data of PK parameters are available in a Chinese population; none are available regarding a recently developed generic formulation. OBJECTIVE: To meet the requirements for marketing a new generic product in China, the study was designed to compare the PK properties and bioequivalence of 2-mg tablets of glimepiride: the newly developed generic formulation (test) and a branded formulation (reference) in healthy Chinese male volunteers. METHODS: A single-dose, randomized-sequence, open-label, 2-way crossover study was conducted in fasted healthy Chinese male volunteers. Eligible participants were randomly assigned in a 1:1 ratio to receive 1 tablet (2 mg each) of the test or reference formulation, followed by a 1-week washout period and administration of the alternate formulation. The study drugs were administered after a 10-hour overnight fast. Plasma samples were collected before study drug administration (baseline) and at 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 10, 12, 24, and 48 hours after study drug administration. Concentrations in plasma of the parent glimepiride and its M1 metabolite were analyzed with a LC-MS/MS method. The formulations were considered bioequivalent if the 90% CIs for the log-transformed values were within the predetermined equivalence range (70%-143% for C(max) and 80%-125% for AUC), according to the guidelines of the State Food and Drug Administration (SFDA) of China. Tolerability was based on the recording of adverse events (AEs), monitoring vital signs, ECGs, and laboratory tests at baseline and completion of the study. RESULTS: A total of 24 healthy Chinese male volunteers were enrolled and completed the study; however, only the data from 23 subjects were included (mean [SD] age, 23.6 [2.2] years [range, 18.6-26.9 years]; weight, 64.0 [8.4] kg [range, 52.0-82.0 kg]; and height, 172.3 [5.6] cm [range, 164.0-185.0 cm) in the PK and tolerability assessments due to a violation of the protocol. For parent glimepiride, the 90% CIs for the ratios of Cmax, AUC(0-t), and AUC(0-infinity) were 93.83% to 115.19%, 90.82% to 102.29%, and 92.22% to 103.78%, respectively. For the M1 metabolite, the 90% CIs were 91.71% to 110.79%, 91.33% to 101.76%, and 89.99% to 99.85%. Both met the predetermined criteria for bioequivalence. Four AEs (17.4%) were reported: hypertriglyceridemia (2 subjects [8.7%]; 1 each receiving the test and reference formulations); increase of red blood cells in urine (1 subject [4.3%] receiving the reference formulation); and hypoglycemia (1 subject [4.3%] receiving the test formulation). The incidence of hypoglycemia was the only AE considered probably related to study drug administration; all others were considered probably not related. All AEs were transient and considered by the investigators to be mild. CONCLUSIONS: In this small study in fasted healthy Chinese male volunteers, a single 2-mg dose of the test formulation met the regulatory criteria to assume bioequivalence to the reference formulation based on the rate and extent of absorption. Both formulations were well tolerated. SFDA Registration No.: 2009L01033.

Pharmacokinetics and bioequivalence evaluation of two losartan potassium 50-mg tablets: A single-dose, randomized-sequence, open-label, two-way crossover study in healthy Chinese male volunteers.

BACKGROUND: Losartan is a nonpeptide angiotensin II receptor antagonist used as an antihypertensive agent. The relative bioavailability of a newly developed tablet compared with an established branded formulation has not been reported in a Chinese population. OBJECTIVE: To meet the requirements for marketing a new generic product, the study was designed to compare the pharmacokinetic parameters and relative bioavailability of a new generic losartan potassium 50-mg tablet (test formulation) with a branded 50-mg tablet (reference formulation) in healthy Chinese male volunteers. METHODS: A single-dose, randomized-sequence, openlabel, 2-way crossover study was conducted in healthy Chinese male volunteers. Eligible participants were randomly assigned in a 1:1 ratio to receive a single 50-mg tablet of the test or reference formulation, followed by a 1-week washout period and then administration of the alternate formulation. The study drugs were administered after a 10-hour overnight fast. Plasma samples were collected over 36 hours. Tolerability was evaluated by recording adverse events (AEs) and monitoring vital signs, ECGs, and laboratory tests at baseline and at completion of the study. Plasma concentrations of losartan and its active metabolite (EXP3174) were analyzed by LC-MS/MS. Pharmacokinetic parameters, including C(max), AUC(0-36), and AUC(0-infinity), were calculated. If the 90% CIs for the log-transformed values of AUC were within 80% to 125%, and that of C(max) was within 70% to 143%, the 2 products would be considered bioequivalent according to the guidelines of the US Food and Drug Administration and the State Food and Drug Administration of China. RESULTS: Twenty-seven healthy Chinese male volunteers participated in this study (mean [SD] age, 24.5 [2.3] years [range, 20-29 years]; weight, 64.6 [4.0] kg [range, 60.0-75.0 kg]; height, 172.2 [4.8] cm [range, 165.0183.0 cm]; and body mass index, 21.8 [1.2] kg/m(2) [range, 20.0-25.0 kg/m(2)]). One volunteer (3.7%) experienced an AE (microscopic hematuria) after administration of the test formulation. This resolved spontaneously after 10 days and was considered by the investigator as mild; the relationship with the study drug was uncertain. No serious AEs were reported. Both formulations were associated with significant reductions in systolic and diastolic blood pressure and significant increases in heart rate compared with baseline values (all, P < 0.05). No period, formulation, or sequence effects were observed for any pharmacokinetic parameter, except for a significant subject effect. For parent losartan, the 90% CIs for the ratios (test/reference) of C(max), AUC(0-36), and AUCAUC(0-infinity) were 83.65% to 113.36%, 89.79% to 98.25%, and 90.95% to 99.55%, respectively. For the metabolite EXP3174, the 90% CIs for the ratios of C(max), AUC(0-36), and AUCAUC(0-infinity) were 93.49% to 103.61%, 96.79% to 104.09%, and 97.06% to 105.83%. Both C(max) and AUC met the predetermined criteria for assuming bioequivalence. The relative bioavailability of the test formulation to the reference formulation was 93.92% for losartan and 100.40% for EXP3174. CONCLUSIONS: In this small study in healthy Chinese male volunteers, a single 50-mg oral dose of a losartan potassium tablet (test formulation) met the regulatory criteria for assuming bioequivalence to the established reference formulation. Both formulations were well tolerated.

Pharmacokinetics and bioequivalence evaluation of two different atorvastatin calcium 10-mg tablets: A single-dose, randomized-sequence, open-label, two-period crossover study in healthy fasted Chinese adult males.

BACKGROUND: Atorvastatin calcium is a 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor indicated for the prevention of cardiovascular disease and for the treatment of dyslipidemia. Information on the pharmacokinetics of atorvastatin in a Chinese population is lacking, and regulatory requirements necessitate a bioequivalence study for the marketing of a generic product in China. OBJECTIVE: The aim of the present study was to assess the pharmacokinetics and bioequivalence of a test and branded reference formulation of atorvastatin calcium 10-mg tablets in healthy fasted Chinese male volunteers. METHODS: This was a single-dose, randomized-sequence, open-label, 2-period crossover study with a 2-week washout period between doses. Healthy Chinese males were randomly assigned to receive 20 mg of either the test or reference formulation, and 13 blood samples were obtained over a 48-hour interval. Plasma concentrations of parent atorvastatin and ortho-hydroxy-atorvastatin (primary active metabolite) were simultaneously determined using a validated liquid chromatography-isotopic dilution mass spectrometry method. Pharmacokinetic parameters, including C(max), T(max), t((1/2)), AUC(0-t), and AUC(0-infinity)), were calculated. The 2 formulations were to be considered bioequivalent if 90% CIs for the log transformed ratios of AUC and C(max) of atorvastatin were within the predetermined bioequivalence range (0.80-1.25 for AUC and 0.70-1.43 for C(max)) as established by the State Food and Drug Administration of China. Tolerability was evaluated throughout the study by vital signs monitoring, physical examinations, 12-lead ECGs, and subject interviews on adverse events (AEs). RESULTS: A total of 66 subjects were assessed for inclusion; 20 were excluded prior to study initiation. Of the 46 healthy subjects (mean [SD] age, 24.1 [2.5] years; height, 170.8 [5.1] cm; weight, 64.6 [6.4] kg; body mass index (BMI), 22.1 [1.7] kg/m(2)) who completed the study, 45 subjects (mean [SD] age, 24.1 [2.5] years; height, 171.1 [4.9] cm; weight, 64.8 [6.3] kg; BMI, 22.1 [1.7] kg/m(2)) were included in the pharmacokinetic and bioequivalence analyses; 1 subject was excluded from these analyses because he mistakenly received the same formulation in both periods. No period or sequence effect was observed. The mean values of C(max), AUC(0-t), and AUC(0-infinity)) for the test and reference formulations of atorvastatin (8.78 and 10.76 ng/mL, 38.22 and 40.02 ng/mL/h, 42.73 and 44.51 ng/mL/h, respectively) and ortho-hydroxy-atorvastatin (5.78 and 5.77 ng/mL, 47.32 and 48.47 ng/mL/h, 52.36 and 53.14 ng/mL/h) were not significantly different. The 90% CIs for natural log-transformed ratios of C(max), AUC(0-t), and AUC(0-infinity)) of both atorvastatin (0.73-0.91, 0.92-1.02, and 0.91-1.01, respectively) and ortho-hydroxy-atorvastatin (0.83-1.05, 0.92-1.02, and 0.93-1.02) were within the bioequivalence acceptance limits. Three subjects (6.5%) reported a total of 4 mild AEs (1 abdominal discomfort and 3 venipuncture syncope), which were not considered to be associated with administration of the study drug. CONCLUSIONS: This single-dose (20 mg) study found that the test and reference formulations of atorvastatin calcium 10-mg tablet met the regulatory definition for assuming bioequivalence in these healthy fasted Chinese male volunteers. Both formulations were generally well tolerated in the population studied. Chinese National Registry Code: 2007L02512.

Simultaneous determination of itraconazole and hydroxyitraconazole in human plasma by liquid chromatography-isotope dilution tandem mass spectrometry method.

A rapid and sensitive liquid chromatography-isotope dilution tandem mass spectrometry method was developed and validated for quantification of itraconazole (ITZ) and its active metabolite hydroxyitraconazole (OH-ITZ ) in human plasma. The plasma samples were extracted with tert-butyl methyl ether and two isotope-labeled internal standards (D5-itraconazole and D5-hydroxyitraconazole) were used. The chromatographic separation was performed on a Capcell Pak C(18) MG III (100 x 2 mm, 5 microm, Shiseido). The protonated ions of analytes were detected in positive ionization in multiple reaction monitoring mode. The plasma method has a lower limit of quantification of 1 ng/mL with a linearity range of 1-500 ng/mL for ITZ and OH-ITZ using 100 microL of plasma. The recoveries of the method were found to be 69.47-71.98% for ITZ and 75.68-82.52% for OH-ITZ. The intra- and inter-batch precision was less than 11% for all quality control samples at concentrations of 2.5, 200 and 400 ng/mL. These results indicate that the method was efficient with a short run time (4.5 min) and acceptable accuracy, precision and sensitivity.The validated method was successfully applied to analysis of human plasma samples in pharmacokinetics study.

Secretome-based identification of Mac-2 binding protein as a potential oral cancer marker involved in cell growth and motility.

Oral squamous cell carcinoma (OSCC) is the 11th most common cancer worldwide, and is associated with a high death rate. At present, there are no suitable markers for detecting and/or monitoring OSCC in body fluids/tissues. Here, we used 1D SDS-PAGE and MALDI-TOF MS to systematically analyze the secretomes of two OSCC cell lines (OEC-M1 and SCC4). The putative OSCC-related proteins identified in this analysis included the Mac-2 binding protein (Mac-2 BP), which was further found to be overexpressed in OSCC specimens and significantly elevated in the sera of OSCC patients compared to healthy controls. Finally, RNA interference-based knock-down of Mac-2 BP expression in OSCC cells revealed for the first time that Mac-2 BP is involved in regulating growth and motility of OSCC cells.

Increased thermal and organic solvent tolerance of modified horseradish peroxidase.

Horseradish peroxidase (HRP) was modified by maleic anhydride and citraconic anhydride. The thermal and organic solvent tolerances of native and modified enzyme were compared. These chemical modifications of HRP increased their thermostability both in aqueous buffer and some organic solvents, and also enhanced their tolerances of some organic solvents. We have studied the unfolding of native and modified HRP by heat to determine the conformational stability. The temperature at the midpoint of thermal denaturation (T(m)) was increased upon modification. Both enthalpy change (DeltaH(m)) and entropy change (DeltaS(m)) for unfolding of modified enzyme at T(m) were decreased compared with native enzyme. Circular dichroism studies proved that these modifications changed the conformation of HRP. The improvements of stability are related to side chain reorientations of aromatics upon both modifications.

Understanding the effects of soil characteristics on phytotoxicity and bioavailability of nickel using speciation models.

Acidity (pH) has been realized to be the most important soil characteristic that modulates bioavailability of heavy metals by affecting both the chemical speciation of metals in soil and the metal binding to the active sites on biota. In this work, we show that besides soil pH, metal bioavailability also depends to a certain extent on the type of soil. A better understanding of the role of soil type in regulating metal availability can be achieved with the analysis of soil composition and with calculations using chemical speciation models. Results of pot experiments, in which three different soils were spiked with nickel, show that the EC50 of total nickel in decreasing the biomass production of oats varies widely (0.7-22.5 mmol kg(-1) soil, more than 30 times). pH (4.7-7.0) is the most important factor, explaining up to a factor of 14 difference of nickel bioavailability in the soils. The remaining variation is caused by other differences in soil composition (soil type). The bioavailability and toxicity of nickel in the organic matter-rich soil studied is less than half of that in the sandy and clay soil studied at a similar pH. The chemical calculations using a multi-surface speciation model show that soil organic matter binds Ni much stronger than clay silicates and iron (hydr)oxides within the acidic pH range, which supports the experimental findings. In all three soils, the EC50 of Ni expressed in terms of Ni in 0.01 M CaCl2 soil extraction is rather stable (24-58 microM), suggesting the possibility to use this extraction as an estimation of metal availability in soil.

Screening and mutagenesis of Aspergillus niger for the improvement of glucose 6-phosphate dehydrogenase production.

The strain of Aspergillus niger ZBY-7 was selected as the original strain of glucose 6-phosphate dehydrogenase production. After mutagenesis of the strain using UV irradiation and nitrosoguanidine, mutants of Aspergillus niger resistant to certain metabolic inhibitor were obtained. Five of the mutants showed increased glucose 6-phosphate dehydrogenase production. The mutant resistant to antimycin A (Aspergillus niger AM-23) produced the highest level of glucose 6-phosphate dehydrogenase (695.9% of that from the original strain).

Induction of inducible nitric oxide synthase by Epstein-Barr virus B95-8-derived LMP1 in Balb/3T3 cells promotes stress-induced cell death and impairs LMP1-mediated transformation.

The latent membrane protein 1 (LMP1) of Epstein-Barr virus (EBV) causes cellular transformation and activation of several intracellular signaling events. In this report, we show that BLMP1 (encoded by the LMP1 gene derived from the B95-8 strain of EBV) triggers the expression of inducible nitric oxide synthase (iNOS) in Balb/3T3 fibroblasts. Intriguingly, NLMP1, a natural sequence variant of LMP1 identified in EBV-positive nasopharyngeal carcinoma biopsy, does not similarly induce iNOS expression. BLMP1-induced iNOS in Balb/3T3 cells is active to produce nitric oxide (NO), and NO production can be blocked by several iNOS inhibitors. When subjected to environmental stress, Balb/3T3 cells that produce NO lose viability more rapidly than non NO-producing cells. Blockage of NO generation by iNOS inhibitors enhances the viability of NO-producing cells under stress conditions. The activities of caspase-3 and c-Jun N-terminal kinase, two important regulators mediating stress-induced apoptosis, are significantly potentiated following heat shock treatment of BLMP1-expressing/NO-producing cells, compared to parental and NLMP1-expressing cells. Furthermore, treatment with iNOS inhibitor augmented the cloning efficiency (in culture) and tumor growth (in nude mice) of BLMP1-expressing/NO-producing cells. Collectively, the results demonstrate that BLMP1 induces iNOS expression and NO production in Balb/3T3 cells, which leads to the alteration of cell functions, including sensitivity to environmental stress, capability to colonize independent of anchorage and tumorigenicity in nude mice. Our data additionally implicate that the differential iNOS induction potential of the two LMP1 forms may represent the basis of a functional difference between the two LMP1 proteins.