Application of intraoperative photodynamic therapy in patients suspected of recurrence post radical surgery: A single center experience.

BACKGROUND: Difficult to resect tumors may be treated with a combination of radical surgery and photodynamic therapy to try to reduce recurrence. The aim of this single center study is to present results from a combined application of radical surgery with intraoperative PDT for patients with various cancers suspected of high risk for post-operative local recurrence. METHODS: Radical surgery combined with intraoperative PDT was performed in each and every patient under study at different time points from June 2020 to July 2021, and the PDT irradiation time ranged from 10, 20, 25 and 30 min. Hematoporphyrin, as a photo synthesizer, was administered intravenously 48 h before surgery and during the operative period respectively, at a 3 mg/kg dose. In addition, the mean and median survival times for each of these patients were also evaluated. Patient's overall disease-Free Survival (DFS) and survival (OS) were immensely evaluated. RESULTS: 12 patients (33.3% female and 66.7 % male) underwent radical surgery and PDT simultaneously. No photosensitivity events were reported in the included patients, except for one case with a moderate to severe erythema. Intraoperative PDT was tolerated in all included patients without serious liver and kidney damages. As from the time these patients underwent radical surgery and PDT, three mortalities were recorded and the remaining 9 patients had some remarkable outcomes with less or no recurrences. CONCLUSIONS: Intraoperative PDT is a potentially safe therapeutic strategy for various tumor patients who undergo operation. Intraoperative PDT combined with surgery may improve local tumor control but this needs to be tested in a larger patient population.

Photodynamic Therapy in Combination with Chemotherapy, Targeted, and Immunotherapy As a Successful Therapeutic Approach for Advanced Gastric Adenocarcinoma: A Case Report and Literature Review.

Objective: To explore the efficacy of photodynamic therapy combined with chemotherapy, targeted therapy, and immunotherapy in poorly differentiated gastric adenocarcinoma (GAC). Background: Advanced GAC has high malignancy and mortality rate. To date, no study has applied photodynamic treatment (PDT) combined with chemo-, targeted, and immunotherapy to treat this cancer. Patient and methods: Clinical data of a patient diagnosed with poorly differentiated GAC admitted to the department of oncology of the Lanzhou University Second Hospital were retrospectively analyzed. The patient underwent four PDT procedures combined with chemo-, targeted, and immunotherapy. Results: A 72-year-old male patient received combination therapy of PDT. This treatment resolved the cancerous tissues and levels of tumor markers. There was no recurrence and metastasis during a 7-month follow-up. Conclusions: Combination therapy of PDT can effectively treat tumors and may be a method suitable for elderly patients with advanced GAC.

Importation of chloroplast proteins under heat stress is facilitated by their SUMO conjugations.

Chloroplasts are hypersensitive to heat stress (HS). SUMOylation, a critical post-translational modification, is conservatively involved in HS responses. However, the functional connection between SUMOylation and chloroplasts under HS remains to be studied. The bioinformatics, biochemistry, and cell biology analyses were used to detect the SUMOylation statuses of Arabidopsis nuclear-encoded chloroplast proteins and the effect of SUMOylation on subcellular localization of these proteins under HS. PSBR, a subunit of photosystem II, was used as an example for a detailed investigation of functional mechanisms. After a global SUMOylation site prediction of nuclear-encoded chloroplast proteins, biochemical data showed that most of the selected candidates are modified by SUMO3 in the cytoplasm. The chloroplast localization of these SUMOylation targets under long-term HS is partially maintained by the SUMO ligase AtSIZ1. The HS-induced SUMOylation on PSBR contributes to the maintenance of its chloroplast localization, which is dependent on its chloroplast importation efficiency correlated to phosphorylation. The complementation analysis provided evidence that SUMOylation is essential for the physiological function of PSBR under HS. Our study illustrated a general regulatory mechanism of SUMOylation in maintaining the chloroplast protein importation during HS and provided hints for further investigation on protein modifications associated with plant organelles under stress conditions.

PTOX-dependent safety valve does not oxidize P700 during photosynthetic induction in the Arabidopsis pgr5 mutant.

Plastid terminal oxidase (PTOX) accepts electrons from plastoquinol to reduce molecular oxygen to water. We introduced the gene encoding Chlamydomonas reinhardtii (Cr)PTOX2 into the Arabidopsis (Arabidopsis thaliana) wild-type (WT) and proton gradient regulation5 (pgr5) mutant defective in cyclic electron transport around photosystem I (PSI). The accumulation of CrPTOX2 only mildly affected photosynthetic electron transport in the WT background during steady-state photosynthesis but partly complemented the induction of nonphotochemical quenching (NPQ) in the pgr5 background. During the induction of photosynthesis by actinic light (AL) of 130 µmol photons m-2 s-1, the high level of PSII yield (Y(II)) was induced immediately after the onset of AL in WT plants accumulating CrPTOX2. NPQ was more rapidly induced in the transgenic plants than in WT plants. P700 was also oxidized immediately after the onset of AL. Although CrPTOX2 does not directly induce a proton concentration gradient (ΔpH) across the thylakoid membrane, the coupled reaction of PSII generated ΔpH to induce NPQ and the downregulation of the cytochrome b6f complex. Rapid induction of Y(II) and NPQ was also observed in the pgr5 plants accumulating CrPTOX2. In contrast to the WT background, P700 was not oxidized in the pgr5 background. Although the thylakoid lumen was acidified by CrPTOX2, PGR5 was essential for oxidizing P700. In addition to acidification of the thylakoid lumen to downregulate the cytochrome b6f complex (donor-side regulation), PGR5 may be required for draining electrons from PSI by transferring them to the plastoquinone pool. We propose a reevaluation of the contribution of this acceptor-side regulation by PGR5 in the photoprotection of PSI.

Auditory and Visual Stimulation for Abdominal Postoperative Patients Experiencing Enhanced Recovery After Surgery (ERAS).

The Enhanced Recovery After Surgery program can reduce postoperative complications, hospital stay, and overall costs in patients, although the evidence for physical intervention with patients is still lacking. This study provides visual and auditory physical interventions to patients in order to explore the effects of Enhanced Recovery After Surgery following abdominal surgery. The study group consisted of patients who had undergone laparoscopic cholecystectomy, radical resection of gastric cancer, or radical resection of colon cancer; we randomly divided them into a control group and a visual and auditory intervention group. We then monitored the bowel sound frequency and time of the first anal self-exsufflation for both groups after surgery. We found that compared with the control group, patients who had undergone laparoscopic cholecystectomy and radical gastrectomy who received auditory intervention had increased bowel sound frequency and a shorter time until first anal self-exsufflation. In addition, patients with colon cancer who received both auditory and visual stimulation had increased bowel sounds and shorter time until the first anal self-exsufflation. These results suggest that visual and auditory interventions significantly improve patients' gastrointestinal function, shorten the hospitalization period, and reduce complications after operation.

Polydimethylsiloxane/ZIF-8@GO sponge headspace solid-phase extraction followed by GC-MS for the analysis of lavender essential oil.

A novel microwave-assisted (MA) headspace solid-phase extraction (HS-SPE) based on polydimethylsiloxane (PDMS)/ZIF-8@GO sponge was developed for the simultaneous extraction and determination of essential oil constituents in lavender. The PDMS/ZIF-8@GO sponge with a high surface area and excellent adsorption capacity was successfully applied in the HS-SPE process. Microwave-assisted coupled with PDMS/ZIF-8@GO sponge headspace solid-phase extraction followed by GC-MS was proposed. Different experimental parameters were investigated. The optimal conditions were found to be as follows: 2:1 as the quality ratio of ZIF-8 to GO, ZIF-8@GO dosage of 30 mg, microwave power of 600 W, extraction time of 10 min and desorption solvent of n-hexane. This method was successfully applied to the analysis of 11 samples of lavender in different varieties. A total of 52 compounds were identified by the proposed method. A good linearity was observed from 14 to 800 ng with a correlation coefficient (R2) value of >0.99. Multivariate statistical analysis was used to establish the relationship between the varieties and the volatile components for further discriminant analysis. These results demonstrated that the MA-PDMS/ZIF-8@GO is an efficient, sensitive and small sample consumption method for the determination of the essential oil in dried plant materials.

Weighing paper-assisted magnetic ionic liquid headspace single-drop microextraction using microwave distillation followed by gas chromatography-mass spectrometry for the determination of essential oil components in lavender.

Weighing paper-assisted magnetic ionic liquid headspace single-drop microextraction using microwave distillation followed by gas chromatography-mass spectrometry was successfully developed to determine the essential oil components in lavender. The magnetic ionic liquid 1-octyl-3-methylimidazolium tetrachloroferrate was successfully synthesized and used as the optimal extraction solvent. An aliquot of 9 µL of magnetic ionic liquid could be stably suspended on the weighing paper for long time extraction. The increase of the extractant volume resulted in a significantly enhanced in extracting efficiency of the weighing paper-assisted magnetic ionic liquid headspace single-drop microextraction than traditional headspace single-drop microextraction method. In this experiment, the optimal conditions were 1-octyl-3-methylimidazolium tetrachloroferrate as the extraction solvent, extraction time of 12 min, microwave power of 600 W, cyclohexane as back-extractant and sample amount of 30 mg. The developed method was successfully applied to analyze 16 lavender samples from three different harvest years. A total of 39 compounds in lavender were identified and the principal component analysis provided a clear separation between those lavender samples harvested in different years. The results indicated that the proposed weighing paper-assisted magnetic ionic liquid headspace single-drop microextraction is a novel, fast, simple and sensitive microextration technique for the determination of the essential oil components in lavender.

Polydimethylsiloxane/ionic liquid sponge used in headspace solid-phase extraction coupled with GC-MS for rapid analysis of essential oil in lavender.

A headspace (HS) solid-phase extraction (SPE) based on polydimethylsiloxane (PDMS)/ionic liquid (IL) sponge was developed for the extraction of lavender essential oil. The PDMS after loading of 1-butyl-3-methylimidazolium tetrachloroferrate ([BMIM]FeCl4 ) with a high surface area and excellent adsorption capacity was successfully applied in the SPE process. Microwave distillation (MD) coupled with HS-PDMS/[BMIM]FeCl4 extraction after GC-MS was proposed. Various experimental parameters were studied. The optimal conditions were as follows: optimal IL, [BMIM]FeCl4 ; volume ratio of IL to ethanol, 1:5; extraction solvent, n-hexane; microwave power, 600 W; and irradiation time, 12 min. The limits of detection and quantification of the analytic compounds were in the ranges 4.00-16.32 and 10.00-40.00 ng, respectively. The intra-day and inter-day precisions were in the ranges 0.37-1.94% and 1.20-2.45%, respectively. Under the optimized conditions, 13 samples of 3 lavender varieties were analyzed, and 40 compounds were identified. Lavender varieties were distinguished using principal component analysis. The results showed that MD-HS-PDMS/IL-GC-MS is a novel, simple, and sensitive method for the determination of essential oil in complex plant samples.

How to Find Vacant Green Space in the Process of Urban Park Planning: Case Study in Ningbo (China).

Nature-based recreation in urban areas is essential for the well-being of citizens. Park green space (PGS) is a necessary urban infrastructure and a critical step of urban planning and policy-making. The existing research on PGS only focuses on service allocation problems existing in the current urban development, ignoring changes in residential communities accessibility. This research provides new ideas to evaluate PGS. Based on parks and residential communities' data, we adopt an improved Gaussian-based two-step floating catchment area (2SFCA) method to evaluate PGS accessibility in Ningbo (China) and its matching with different levels of residential areas. We present a case study in Ningbo, and discuss its implications for PGS management. This study contains two elements: (a) Compare the current and initial PGS accessibility of each community to accurately identify the communities with PGS vacancies. (b) Analyze and discuss the association between community accessibility and residential house prices. Compare the PGS coverage ratios of communities at different levels to determine the equity of PGS planning in Ningbo. We found that the level of PGS allocation in the central area of Ningbo is high. Obviously, high-value clusters are formed in Sanjiangkou, Zhenhai New Town, Southern and Eastern Yinzhou. The accessibility level in the middle area of Yinzhou is low, and there are super high accessibility residential communities in the outer city area. There is an exact period of green space vacancy in the middle and the outer area. The residential areas with ultra-high accessibility did not configure PGS services at the beginning of their construction. There is no noticeable difference in PGS accessibility of residential communities of different levels at present, but 149 low- and middle-income residential communities lack green space service when the construction was completed. High-end residential communities have priority on enjoying park green space services. Our study suggests that PGS accessibility should be studied temporally and spatially for each residential community. The Ningbo government should strengthen the balanced construction of green space in parks and guarantee green space services for low-end residential communities to improve green space equity.

Functional characterization of a chloroplast-localized Mn2+(Ca2+)/H+ antiporter, ZmmCCHA1 from Zea mays ssp. mexicana L.

The annual Zea mays ssp. mexicana L. is a member of the teosinte group and a close wild relative of maize. Thus, Zea mays ssp. mexicana L. can be effectively used in maize breeding. AtCCHA1 is a Mn2+ and/or Ca2+/H+ antiporter localized in chloroplasts in Arabidopsis. In this study, its homolog from Zea mays ssp. mexicana L., ZmmCCHA1, was isolated and characterized. The transcriptional level of ZmmCCHA1 in Zea mays ssp. mexicana L. was repressed in response to excessive Ca2+ or Mn2+. Heterologous functional complementation assays using yeast mutants showed that ZmmCCHA1 mediates Ca2+ and Mn2+ transport. The ZmmCCHA1 protein was localized in the chloroplasts when expressed in tobacco leaves. Furthermore, ectopic overexpression of ZmmCCHA1 in the Arabidopsis ccha1 mutant rescued the mutant defects on growth and the photosynthetic proteins in the thylakoid membranes. Moreover, the photosynthetic phenotypes of Arabidopsis ccha1 mutant at steady-state were greatly but not completely complemented by the overexpression of ZmmCCHA1. In addition, overexpressing the ZmmCCHA1 rescued the sensitives of PSII in the Arabidopsis ccha1 mutant to Mn2+ deficiency or high Ca2+ condition. These results indicate that the isolated ZmmCCHA1 is the homolog of AtCCHA1 and plays a conserved role in maintaining the Mn2+ and/or Ca2+ homeostasis in chloroplasts which is critical for the function of PSII in photosynthesis.

Modification of Activity of the Thylakoid H+/K+ Antiporter KEA3 Disturbs ∆pH-Dependent Regulation of Photosynthesis.

The thylakoid K+ efflux antiporter 3 (KEA3) is required for regulating components of the proton motive force (pmf), proton concentration gradient (ΔpH), and membrane potential (Δψ). The Arabidopsis (Arabidopsis thaliana) disturbed proton gradient regulation mutant (dpgr) is a dominant allele of KEA3, conferring disturbed transport activity. Here, we show that overexpressing the DPGR-type KEA3 (DPGRox) retarded plant growth, whereas overexpressing the wild-type KEA3 (KEA3ox) did not. In KEA3ox lines, the contribution of Δψ to pmf was enhanced, but in DPGRox lines, the size of pmf was reduced. In DPGRox plants, proton conductivity of the thylakoid membrane (g H +) was elevated under high light, implying disturbed stoichiometry of H+/K+ antiport through DPGR-type KEA3 rather than simply enhanced activity. The ΔpH-dependent regulation consisting of thermal dissipation of excessively absorbed light energy and downregulation of cytochrome b 6 f complex activity was severely and mildly affected in DPGRox and KEA3ox plants, respectively. Consequently, photosystem I was sensitive to fluctuating light in both transgenic plants. Both photosystems were sensitive to constant high light and were slightly photodamaged even at standard growth light intensity in DPGRox plants. KEA3 regulates the components of pmf and optimizes the operation of ∆pH-dependent regulation of electron transport.

Silico analysis of a novel mutation c.550delT in a Chinese patient with maple syrup urine disease.

Twelve days after birth, the child was admitted to hospital because of "poor response, lethargy, and poor appetite for 6 days" and developed into coma immediately. The ventilator is required. The urine had significant maple syrup odor. After different diagnosis, she was diagnosed with classical maple syrup urine disease.

PROTON GRADIENT REGULATION 5 contributes to ferredoxin-dependent cyclic phosphorylation in ruptured chloroplasts.

Antimycin A-sensitive cyclic electron flow (CEF) was discovered as cyclic phosphorylation by Arnon et al. (1954). Because of its sensitivity to antimycin A, PROTON GRADIENT REGULATION 5 (PGR5)/PGR5-like Photosynthetic Phenotype 1 (PGRL1)-dependent CEF has been considered identical to the CEF of Arnon et al. However, this conclusion still needs additional supportive evidence, mainly because of the absence of definitive methods of evaluating CEF activity. In this study, we revisited the classical method of monitoring cyclic phosphorylation in ruptured chloroplasts to characterize two Arabidopsis mutants: pgr5, which is defective in antimycin A-sensitive CEF, and chlororespiratory reduction 2-1 (crr2-1), which is defective in chloroplast NDH-dependent CEF. We observed a significant reduction in CEF-dependent pmf formation and consequently ATP synthesis in the pgr5 mutant, although LEF-dependent pmf formation and ATP synthesis were not impaired at photosynthetic photon flux densities below 130 µmol m-2 s-1. In contrast, the contribution of chloroplast NDH complex to pmf formation and ATP synthesis was not significant. Antimycin A partially inhibited CEF-dependent pmf formation, although there may be further inhibition sites. Unlike in the observation in leaves, the proton conductivity of ATP synthase, monitored as gH+, was not enhanced in ruptured chloroplasts of the pgr5 mutant.

[Determination of trace pentachlorophenol and its sodium salt in animal-origin foods by QuEChERS-ultra performance liquid chromatography-tandem mass spectrometry].

A method was developed for the determination of trace pentachlorophenol and its sodium salt in animal-origin foods by modified QuEChERS-ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Sodium pentachlorophenolate in samples was converted to pentachlorophenol under acidic condition. The pentachlorophenol was extracted twice with acetonitrile containing 1% (v/v) acetic acid by ultrasonic extraction. The extracts were purified by dispersive solid-phase extraction. The usages of dispersive sorbents were optimized based on the recoveries and matrix effects. Chromatographic analysis was conducted on a Waters Acquity UPLC HSS T3 column with gradient elution. The pentachlorophenol was further analyzed by negative electrospray ionization under the multiple reaction monitoring mode. The recoveries at fortification levels of 1.0, 2.0 and 10.0 µg/kg in six matrices (pork, pork liver, chicken, fish, milk and egg) ranged from 73.2% to 108.4% with the relative standard deviations of 4.0%-14.8%. The limits of quantification (S/N>10) were 1.0 µg/kg. The method is simple, sensitive, accurate, economical and environmentally safe, and is suitable for the determination of the trace pentachlorophenol and its sodium salt in animal-origin foods.

Nonabsorbable polysaccharide-functionalized polyethylenimine for inhibiting lipid absorption.

Overweight and obesity, which contribute to various chronic diseases, are increasingly common conditions around the world. For the purpose of weight loss in patients with overweight and obesity, we developed a series of ß-cyclodextrin functionalized cationic branched polyethylenimine as oral pharmaceutical agents to inhibit digestion and absorption of dietary lipids in vivo. Tuning the structural configuration, molecular weight, and side-chain length of the cationic polymers provided the polymer with effective inhibition of lipid absorption. Importantly, the cationic polymer significantly increased fecal elimination of bile acids, triglycerides and cholesterol by 6.3-, 4.8- and 5.0-fold higher than those of the control with high fat diet, respectively. Moreover, the polymer could reduce the plasma lipids and liver lipid level in mice. The cationic polymer exhibited low cytotoxicity and did not cause observable histological changes for normal tissue. Therefore, the cationic polymer showed effective and safe characteristics as an oral pharmaceutical agent for inhibiting lipid absorption. This work offers a new promising venue to control weight for patients with overweight and obesity.

Glutamine Enhances the Hypoglycemic Effect of Insulin in L6 Cells via Phosphatidylinositol-3-Kinase (PI3K)/Protein Kinase B (AKT)/Glucose Transporter 4 (GLUT4) Signaling Pathway.

BACKGROUND Diabetes mellitus (DM) is characterized by a decreased blood level of glutamine (Gln), which may contribute to the disturbance in the effect of insulin on skeletal muscle. Therefore, it is crucial to study how to improve the effect of insulin on skeletal muscle by increasing Gln. In the present study, we investigated the effect of Gln on the hypoglycemic action of insulin in skeletal muscle L6 cells at high glucose levels through the insulin signaling pathway and glycogen synthesis pathway. MATERIAL AND METHODS The L6 cells were cultured in and stimulated by Gln and insulin. The glutamine analogue, L-Gamma-Glutamyl-p-nitroanilide (GPNA), was used for verifying the effect of Gln. The expression of insulin signaling molecules, including phosphatidylinositol-3-kinase (PI3K), 3-phosphoinositide-dependent protein kinase-1 (PDK1), protein kinase B (AKT), protein kinase C zeta (PKCz), and glucose transporter 4 (GLUT4), were detected by real-time PCR and Western blot analysis, GLUT4 translocation was observed by immunofluorescence staining, glycogen synthase kinase (GSK) was analyzed by Western blotting, and glucose uptake was measured by glucose oxidase method (GOD). RESULTS The results demonstrated that Gln combined with insulin remarkably up-regulated PI3K and PDK1 and also increased AKT and PKCz phosphorylation. The present study shows that Gln enhanced the impact of insulin on GLUT4 and its translocation. The results of glucose uptake and GSK phosphorylation further confirmed the hypoglycemic effect of Gln accompanied with insulin. The hypoglycemic effect of Gln was reversed by GPNA. CONCLUSIONS These findings suggest that Gln enhances the hypoglycemic role of insulin through the PI3K/AKT/GLUT4 signaling pathway and glycogen synthesis pathway.

Fine-tuned regulation of the K+ /H+ antiporter KEA3 is required to optimize photosynthesis during induction.

KEA3 is a thylakoid membrane localized K+ /H+ antiporter that regulates photosynthesis by modulating two components of proton motive force (pmf), the proton gradient (∆pH) and the electric potential (∆ψ). We identified a mutant allele of KEA3, disturbed proton gradient regulation (dpgr) based on its reduced non-photochemical quenching (NPQ) in artificial (CO2 -free with low O2 ) air. This phenotype was enhanced in the mutant backgrounds of PSI cyclic electron transport (pgr5 and crr2-1). In ambient air, reduced NPQ was observed during induction of photosynthesis in dpgr, the phenotype that was enhanced after overnight dark adaptation. In contrast, the knockout allele of kea3-1 exhibited a high-NPQ phenotype during steady state in ambient air. Consistent with this kea3-1 phenotype in ambient air, the membrane topology of KEA3 indicated a proton efflux from the thylakoid lumen to the stroma. The dpgr heterozygotes showed a semidominant and dominant phenotype in artificial and ambient air, respectively. In dpgr, the protein level of KEA3 was unaffected but the downregulation of its activity was probably disturbed. Our findings suggest that fine regulation of KEA3 activity is necessary for optimizing photosynthesis.

Rapid determination of 88 veterinary drug residues in milk using automated TurborFlow online clean-up mode coupled to liquid chromatography-tandem mass spectrometry.

A novel method based on TurborFlow online solid phase extraction (SPE) combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been established for simultaneous screening and confirmation of 88 wide-range veterinary drugs belonging to eight families (20 sulfonamides, 7 macrolides, 15 quinolones, 8 penicillins, 13 benzimidazoles, 4 tetracyclines, 2 sedatives, and 19 hormones) in milk. The preparation method consists of sample dilution and ultrasonic extraction, followed by an automated turbulent flow cyclone chromatography sample clean-up system. The detection was achieved in selected reaction monitoring mode (SRM). The total run time was within 39 min, including automated extraction, analytical chromatography and re-equilibration of the turboflow system. The optimization of different experimental parameters including extraction, purification, separation, and detection were evaluated separately in this study. The developed method was validated and good performing characteristics were obtained. The linear regression coefficients (R(2)) of matrix-match calibration standard curves established for quantification were higher than 0.9930. The limits of detection (LOD) were in the range of 0.2-2.0 µg/kg given by signal-noise ratio ≥3 (S/N) and the limits of quantification (LOQ, S/N≥10) ranged between 0.5 µg/kg and 10 µg/kg. Average recoveries of spiked target compounds with different levels were between 63.1% and 117.4%, with percentage relative standard deviations (RSD) in the range of 3.3-17.6%. The results indicated that the developed method has great potential for the routine laboratory analysis of large numbers of samples on measuring different classes of compounds. In comparison to traditional procedures, the automated sample clean-up ensures rapid, effective, sensitive analyses of veterinary drugs in milk.

Role of cyclic electron transport around photosystem I in regulating proton motive force.

In addition to ∆pH formed across the thylakoid membrane, membrane potential contributes to proton motive force (pmf) in chloroplasts. However, the regulation of photosynthetic electron transport is mediated solely by ∆pH. To assess the contribution of two cyclic electron transport pathways around photosystem I (one depending on PGR5/PGRL1 and one on NDH) to pmf formation, electrochromic shift (ECS) was analyzed in the Arabidopsis pgr5 mutant, NDH-defective mutants (ndhs and crr4-2), and their double mutants (ndhs pgr5 and crr4-2 pgr5). In pgr5, the size of the pmf, as represented by ECSt, was reduced by 30% to 47% compared with that in the wild type (WT). A gH+ parameter, which is considered to represent the activity of ATP synthase, was enhanced at high light intensities. However, gH+ recovered to its low-light levels after 20 min in the dark, implying that the elevation in gH+ is due to the disturbed regulation of ATP synthase rather than to photodamage. After long dark adaptation more than 2 h, gH+ was higher in pgr5 than in the WT. During induction of photosynthesis, gH+ was more rapidly elevated in pgr5 than that in the WT. Both results suggest that ATP synthase is not fully inactivated in the dark in pgr5. In the NDH-deficient mutants, ECSt was slightly but significantly lower than in the WT, whereas gH+ was not affected. In the double mutants, ECSt was even lower than in pgr5. These results suggest that both PGR5/PGRL1- and NDH-dependent pathways contribute to pmf formation, although to different extents. This article is part of a Special Issue entitled: Chloroplast Biogenesis.

[Rapid determination of total residues of ribavirin and its metabolites in chicken and chicken products by ultra-performance hydrophilic interaction chromatography-tandem mass spectrometry].

An analytical method was developed for the determination of total residues of ribavirin and its phosphorylated metabolites in chicken and its products by hydrophilic interaction chromatography-tandem mass spectrometry. The samples were extracted with acetonitrile containing 1% (v/v) acetic acid under ultrasonic condition and then enzymatically hydrolysed with acid phosphatase at 37 degrees C. After liposoluble substances being removed with hexane, C18 and PSA dispersion solid phase extraction (DSPE) was introduced to cleanup procedures. The separation was performed on an ultra-performance hydrophilic interaction chromatographic (HILIC) amide column under a gradient elution using acetonitrile and 0.1% formic acid. The analytes were detected in the positive electrospray ionization and multi-reaction monitoring (MRM) mode. In the range of 1-200 microg/kg, the correlation coefficient was greater than 0.999. The limit of detection (LOD, S/N > or = 3) was 1 microg/kg and the limit of quantification (LOQ, S/N > or = 10) was 5 microg/kg. The recoveries of ribavirin spiked at three levels ranged from 67.8% to 112.7% with the relative standard deviations (RSDs) of 6.1%-13.6%. The results of the determination of ribavirin in various real samples showed that the method is simple, rapid, accurate and suitable for the determination of total residues of ribavirin and its metabolites in chicken and its products.