JrGA20ox1-transformed rootstocks deliver drought response signals to wild-type scions in grafted walnut.

Targeted regulation using transgrafting technology has become a trend. However, the mechanisms of transgene-derived signal communication between rootstocks and scions remain unclear in woody plants. Here, we grafted wild-type (WT) walnut (Juglans regia L.) on WT (WT/WT), JrGA20ox1 (encodes a gibberellin 20-oxidase)-overexpressing (WT/OE), and JrGA20ox1-RNAi transformation (WT/RNAi) walnut in vitro. We aimed to elucidate the mechanisms of JrGA20ox1-derived signal communication under PEG-simulated drought stress between rootstocks and scions in walnut. We demonstrated that JrGA20ox1-OE and JrGA20ox1-RNAi rootstocks could transport active gibberellins (GAs) and JrGA20ox1-RNAi vector-produced sRNAs to WT scions under PEG-simulated drought stress, respectively. The movement of sRNAs further led to a successive decline in JrGA20ox1 expression and active GA content. Meanwhile, unknown mobile signals may move between rootstocks and scions. These mobile signals reduced the expression of a series of GA-responsive and GA-non-responsive genes, and induced ROS production in guard cells and an increase in ABA content, which may contribute to the drought tolerance of WT/RNAi, while the opposite occurred in WT/OE. The findings suggest that JrGA20ox1-derived rootstock-to-scion movement of signals is involved in drought tolerance of scions. Our research will provide a feasible approach for studying signal communication in woody plants.

Direct comparison of LC-MS/MS and RIA methods for the pharmacokinetics assessment of human insulin in preclinical development.

Insulin is an effective therapeutic for diabetes, and the level of insulin in vivo is directly related to the health of diabetic patients. Traditionally, the concentrations of insulin in vivo are determined by the radioimmunoassay (RIA) method. In this study, we developed an LC-MS/MS method for the quantification of human insulin in dog plasma and directly compared the RIA and LC-MS/MS methods. Our LC-MS/MS method exhibited superior accuracy, efficiency and cost-effective for the pharmacokinetic (PK) assessment of human insulin. The LC-MS/MS method can quantitate human insulin and canine insulin simultaneously without cross-reactivity, making the analysis more efficient. The LLOQ of our LC-MS/MS method was 38.5 pg/mL, which was necessary to fully describe the PK profiles of endogenous and exogenous insulin in vivo. The direct comparison of PK data obtained from the two methods demonstrated that LC-MS/MS could be an alternative to the RIA method and should be widely used for the quantification of insulin drugs, especially in preclinical studies.

Determination of liraglutide in rat plasma by a selective liquid chromatography-tandem mass spectrometry method: Application to a pharmacokinetics study.

A simple, sensitive and selective LC-MS/MS method was developed for the quantitative analysis of liraglutide and validated in rat plasma. Human insulin was used as the internal standard. After a simple protein precipitation step, liraglutide was chromatographically separated using an InertSustain Bio C18 column with mobile phases comprising acetonitrile with 0.1% formic acid (A) and water with 0.1% formic acid (B). Detection was achieved using positive ion electrospray ionization in multiple-reaction monitoring (MRM) mode. Good linearity was observed in the concentration range 0.5-250 ng/mL (r2 > 0.99). The intra- and inter-day precision values (expressed as relative standard deviation, RSD) of liraglutide ranged from 1.97-7.63% and 5.25-11.9, respectively. The accuracy (expressed as relative error, RE) ranged from -8.79-11.4%. Both the recovery and matrix effect were within acceptable limits. This method was successfully applied for the pharmacokinetics study of liraglutide in rats after subcutaneous administration.

Determination of human insulin in dog plasma by a selective liquid chromatography-tandem mass spectrometry method: Application to a pharmacokinetic study.

A simple, sensitive and selective LC-MS/MS method for quantitative analysis of human insulin was developed and validated in dog plasma. Insulin glargine was used as the internal standard. After a simple step of solid-phase extraction, the chromatographic separation of human insulin was achieved by using InertSustain Bio C18 column with a mobile phase of acetonitrile containing 1% formic acid (A)-water containing 1% formic acid (B). The detection was performed by positive ion electrospray ionization in multiple-reaction monitoring (MRM) mode. Good linearity was observed in the concentration range of 1-1000 µIU/mL (r2 > 0.99), and the lower limit of quantification was 1 µIU/mL (equal to 38.46 pg/mL). The intra- and inter-day precision (expressed as relative standard deviation, RSD) of human insulin were ≤12.1% and ≤13.0%, respectively, and the accuracy (expressed as relative error, RE) was in the range of -7.23-11.9%. The recovery and matrix effect were both within acceptable limits. This method was successfully applied for the pharmacokinetic study of human insulin in dogs after subcutaneous administration.

[Simultaneous determination of salidroside and tyrosol in Beagle dog plasma using UHPLC-MS/MS after pre-column dansyl chloride derivatization].

A pre-column derivatization method combined with UHPLC-MS/MS was developed for the simultaneous determination of salidroside and tyrosol in Beagle dog plasma. After protein precipitation by acetonitrile, the liquid supernatant was treated with dansyl chloride under dark conditions at 60 ℃ for 30 min, and then, the sample solution was extracted using methyl tertiary butyl ether. The multiple reaction monitoring in positive ion mode was used for MS detection of the tested analytes with the specific ion transitions of m/z 534.2→372.0 for salidroside derivative, m/z 372.0→171.0 for tyrosol derivative and m/z 506.0→171.0 for arbutin derivative. The chromatograph separation was achieved on an ACQUITY UPLC® BEH C18 column (100 mm × 2.1 mm, 1.7 µm) with a gradient mobile phase consisting of acetonitrile (0.1% formic acid)-water (10% acetonitrile, 0.1% formic acid) for 9 min. The assay showed a good linearity over the range of 0.02/0.1 − 20/10 µmol·L−1 with a lower limit of quantitation of 0.02 and 0.1 µmol·L−1 for salidroside and tyrosol in dog plasma, respectively. The intra- and inter-day precisions were all less than 8.68%, and the accuracy was within ±11.4%. The established method with a high sensitivity, good specificity and reliability was appropriate for simultaneous determination of salidroside and tyrosol in dog plasma and successfully applied to a pharmacokinetic study after intragastric administration of salidroside to Beagle dogs.

[Simultaneous determination of clevidipine butyrate and its metabolite clevidipine acid in dog blood by liquid chromatography-tandem mass spectrometry].

A rapid, sensitive and simple liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the simultaneous determination of clevidipine butyrate and its primary metabolite clevidipine acid in dog blood. After one-step protein precipitation with methanol, the chromatographic separation was carried out on an Ecosil C18 column (150 mm x 4.6 mm, 5 µm) with a gradient mobile phase consisting of methanol and 5 mmol · L(-1) ammonium formate. A chromatographic total run time of 13.0 min was achieved. The quantitation analysis was performed using multiple reaction monitoring (MRM) at the specific ion transitions of m/z 454.1 [M-H]- --> m/z 234.1 for clevidipine butyrate, m/z 354.0 [M-H]- --> m/z 208.0 for clevidipine acid and m/z 256.1 [M-H]- --> m/z 227.1 for elofesalamide (internal standard, IS) in the negative ion mode with electrospray ionization (ESI) source. The linear calibration curves for clevidipine butyrate and clevidipine acid were obtained in the concentration ranges of 0.5-100 ng · mL and 1-200 ng · mL(-1), separately. The lower limit of quantification of clevidipine butyrate and clevidipine acid were 0.5 ng · mL(-1) and 1 ng · mL(-1). The intra and inter-assay precisions were all below 12.9%, the accuracies were all in standard ranges. Stability testing indicated that clevidipine butyrate and clevidipine acid in dog blood with the addition of denaturant methanol was stable under various processing and/or handling conditions. The validated method has been successfully applied to a pharmacokinetic study of clevidipine butyrate injection to 8 healthy Beagle dogs following intravenous infusion at a flow rate of 5 mg · h(-1) for 0.5 h.

Quantitation of ursolic acid in human plasma by ultra performance liquid chromatography tandem mass spectrometry and its pharmacokinetic study.

Ursolic acid is a hydroxy pentacyclic triterpene, which proved to have sedation, anti-inflammatory, antibacterial, antiulcer and anti-cancer activities. An ultra-performance liquid chromatography/tandem mass spectrometry (UPLC/MS/MS) method with high selectivity, sensitivity and throughput has been established and validated for quantitation of total ursolic acid in human plasma. Plasma samples were pretreated by liquid-liquid extraction with ethyl acetate and were chromatographed by an ACQUITY UPLC BEH C(8) column (100 mm×2.1 mm, I.D., 1.7 µm) using mobile phase consisting of acetonitrile and 10 mM ammonium formate (90:10, v/v) at 0.2 mL/min. The duration of chromatography analysis was 3 min. The multiple reaction monitoring (MRM) was performed at m/z 455.1→455.0 for ursolic acid and m/z 469.3→425.2 for glycyrrhetinic acid (internal standard, IS) in the negative ion mode with electrospray ionization (ESI) source. The assay showed good linearity over the range of 10-5000 ng/mL for ursolic acid in human plasma with a lower limit of quantitation of 10 ng/mL. The mean extraction recovery was 73.2±4.5% and the matrix ion suppression ranged from -11.4% to -5.6%. The intra- and inter-day precisions were less than 7.0% and 7.2%, respectively, and the accuracy was within ±2.0%. Ursolic acid was stable during the analysis and the storage period. The validated method has been successfully applied to a pharmacokinetic study after intravenous infusion of Ursolic Acid Nano-liposomes to healthy volunteers.

[Effects of Shenmai Injection on serum concentration and pharmacokinetics of digoxin in dogs with heart failure].

OBJECTIVE: To explore the effects of Shenmai Injection (SMI), a compound traditional Chinese herbal medicine, on pharmacokinetics and serum concentration of digoxin when applied together with digoxin. METHODS: Twenty dogs with heart failure were randomly divided into 4 groups: control group and low-, medium- and high-dose SMI groups, with 5 dogs in each group. After intravenous injection of digoxin injection at a dose of 7.41 µg/kg, dogs in the control group were administered intravenously with normal saline 20 mL daily for 5 d, and the other groups were intravenously administered with SMI at the doses of 0.517, 1.034 and 1.551 mL/kg respectively. After the administration, the blood was collected at designed time points. Serum concentration of digoxin was determined by high-performance liquid chromatography with electrospray tandem mass spectrometry (HPLC/MS/MS). RESULTS: The low-, medium- and high-dose SMI showed different effects on the pharmacokinetics of digoxin: the low-, medium- and high-dose SMI revealed a tendency to decrease the elimination half-life (T(1/2ß)) of digoxin. The low-dose SMI showed a tendency to decrease the digoxin concentration. Serum clearance (CL) in the low-dose SMI group was higher than that in the control, and also significantly higher than those in the medium- and high-dose SMI groups (P<0.05). The area under concentration-time curve (AUC(0→∞)) in the low-dose SMI group was lower than that in the control group (P=0.05); the AUC(0→72 h) and AUC(0→∞) in the low-dose SMI group were significantly lower than those in the medium- and high-dose SMI groups. Low-dose SMI accelerated the clearance of digoxin in blood. CONCLUSION: Low-, medium- and high-dose SMI shows different effects on pharmacokinetics of digoxin and reveals a tendency to shorten T(1/2ß) of digoxin. Low-dose SMI can accelerate the clearance of digoxin in blood.

Improved HPLC method for doxorubicin quantification in rat plasma to study the pharmacokinetics of micelle-encapsulated and liposome-encapsulated doxorubicin formulations.

An improved simple, rapid and accurate HPLC method for quantification of doxorubicin derived from micelle-encapsulated or liposome-encapsulated doxorubicin formulation in rat plasma was described. The mobile phase consisting of a mixture of methanol-water [containing 0.1% formic acid anhydrous and 0.1% ammonia solution (25%), pH 3.0], 60:40, was delivered at a flow rate of 1.0 mL/min. Sample preparation for micelle- or liposome-encapsulated doxorubicin in rat plasma were achieved directly by protein precipitation with acetonitrile. Doxorubicin and daunorubicin (internal standard, IS) were separated on a C(18) reversed-phase HPLC column and quantified by a fluoresence detection with an excitation wavelength of 475 nm and an emission wavelength of 580 nm. The linearity was obtained over the range of 5.0-1000.0 ng/mL and 1.0-200.0 microg/mL for doxorubicin and the lower limit of quantitation was 5.0 ng/mL. For each level of quality control samples, inter- and intra-assay precision was less than 9.6 and 5.1% (relative standard deviation), respectively, and percentage error was within +/-2.6%. The extraction recoveries of doxorubicin in the range of 10 ng/mL to 100 microg/mL in rat plasma were between 94.1 and 105.6%. This method was successfully applied to the pharmacokinetic study of doxorubicin formulations after i.v. administration to rats.

Determination of metolazone in human blood by liquid chromatography with electrospray ionization tandem mass spectrometry.

A rapid, sensitive and accurate liquid chromatographic-tandem mass spectrometric method is described for the determination of metolazone in human blood. Metolazone was extracted from blood using ethyl acetate and separated on a C18 column interfaced with a triple quadrupole tandem mass spectrometer. The mobile phase consisting of a mixture of acetonitrile, 10 mmol/l ammonium acetate and formic acid (60:40:0.1, v/v/v) was delivered at a flow rate of 0.5 ml/min. Electrospray ionization (ESI) source was operated in positive ion mode. Selected reaction monitoring (SRM) mode using the transitions of m/z 366-->m/z 259 and m/z 321-->m/z 275 were used to quantify metolazone and the lorazepam (internal standard), respectively. The linearity was obtained over the concentration range of 0.5-500 ng/ml for metolazone and the lower limit of quantitation (LLOQ) was 0.5 ng/ml. For each level of QC samples, inter- and intra-run precision was less than 8.07 and 3.56% (relative standard deviation (RSD)), respectively, and the bias was within +/-4.0%. This method was successfully applied to the pharmacokinetic study of metolazone formulation after oral administration to humans.

Simultaneous determination of ZT-1 and its metabolite Huperzine A in plasma by high-performance liquid chromatography with ultraviolet detection.

ZT-1 is a novel acetylcholinesterase (AChE) inhibitor. It is rapidly transformed to Huperzine A (Hup A) in vitro. A simple and rapid HPLC-UV method for the simultaneous determination of ZT-1 and its metabolite Hup A in plasma is described. The chromatographic separations were achieved on a C(18) ODS column (250 mm x 4.6 mm ID) using methanol-1 mmol/L ammonium acetate (70:30,v/v) as mobile phase. The flow rate was 0.7 mL/min, the detection wavelength was 313 nm and the column temperature was kept at 35 degrees C. Plasma samples were prepared as rapidly as possible and extracted immediately with 5 mL of chloroform:iso-propyl alcohol mixture (v/v, 9:1). The retention times of ZT-1 and Huperzine A (Hup A) were 18.7 and 14.4 min, respectively. The mean absolute recoveries of two analytes were >90%. Quantification limits were all 0.02 nmol/mL for ZT-1 and Hup A. This analytical method was reliable and convenient procedure that meets the criteria for the pharmacokinetic evaluation of ZT-1 on experimental animals.

[Tissue distribution and excretion of bromotetrandrine in rats].

AIM: To study the tissue distribution and excretion of bromotetrandrine (W198) in rats. METHODS: The concentrations of W198 in biological samples were determined by an HPLC method with UV detection. RESULTS: After a single i.v. dose of 20 mg x kg(-1) W198 in rats, the parent drug concentrations in tissues were higher than those in blood at the same time. Parent drug was mainly distributed in lung, kidney, heart and liver, the peak levels were attained at 0.25 h and decreasing at 2 h after dosing in most tissues. After a single iv dose of 20 mg x kg(-1) W198 in rats, the excretion of the parent drug in urine, feces and bile amounted to 0. 150%, 2.1% and 0.063% of the dose, respectively. CONCLUSION: W198 was mostly distributed in lung. The parent drug excretion was less than 3% via urine, feces and bile.

[Pharmacokinetics of bromotetrandrin (W198) in rats and beagle dogs].

AIM: To study the pharmacokinetics of bromotetrandrine (W198) in rats and beagle dogs. METHODS: The concentrations of W198 in serum were determined using HPLC method with UV detection. RESULTS: The pharmacokinetic parameters of W198 after single iv doses of W198 10, 20 and 40 mg x kg(-1) in rats were as follows: T1/2beta were 6.60, 7.36 and 6.77 h, AUC0-24 h were 3.797, 7.371 and 15.192 mg x h x L(-1), Vd were 7.14, 4.33 and 4.13 L x kg(-1), CL were 2.83, 2.60 and 2.71 L x (kg x h)(-1), respectively. The T1/2beta and AUCo-24 h of W198 after single im dose of W198 20 mg x kg(-1) in rats were 11.61 h and 12.646 mg x h x L(-1). The im bioavailability of W198 in rats was 56.9%. The T1/2beta, AUC0-24 h, Vd and CL of W198 after single iv dose of W198 5 mg x kg(-1) in beagle dogs were 11.72 h, 12.646 mg x h x L(-1), 0.70 L x kg(-1) and 0.46 L x (kg x h)(-1), respectively. The plasma protein binding ratio of W198 with human serum protein was 78.0%. CONCLUSION: The absorption of W198 in rats was of first order kinetics.

Determination of vertilmicin in rat serum by high-performance liquid chromatography using 1-fluoro-2,4-dinitrobenzene derivatization.

A procedure for the high-performance liquid chromatographic determination of vertilmicin in rat serum was described using pre-column derivatization. The serum proteins were precipitated with acetonitrile and vertilmicin in the supernatant was derivatized with 1-fluoro-2,4-dinitrobenzene. Etimicin was selected as the internal standard. The mobile phase consisted of methanol--20mM ammonium acetate (80:20, v/v), and flow-rate was 0.9 ml/min. Ultraviolet detection was set at 365 nm. The reaction products were chromatographed on a C(18) column kept at 40 degrees C. A good linearity was found in the range of 0.5-250 microg/ml. Both intra- and inter-day precisions of vertilmicin, expressed as the relative standard deviation, were less than 7.4%. Accuracy, expressed as the relative error, ranged from -0.1 to 3.6%. The mean absolute recovery of vertilmicin at three different concentrations was 92.5%. Serum volumes of 50 microl were sufficient for the determination of vertilmicin. The method was proved suitable for the pharmacokinetic study of vertilmicin in rats.