Biomedical subjects

Li Ding

Publications and source records attributed to Li Ding.

72 records · Page 4Linked to original sources

PubMed2004

[Prokaryotic expression of an antigen gene of Trichinella spiralis and identification of the recombinant protein].

OBJECTIVE: To obtain the recombinant protein of an antigen gene Ts88 of Trichinella spiralis and identify the characteristics of the recombinant protein. METHODS: Ts88 cDNA obtained by immunoscreening the cDNA library of adult T. spiralis was subcloned into the pET-28c(+) expression vector and expressed in E. coli. Mice were immunized with the fusion protein incorporated into Freund' s adjuvant and the immune sera were collected. The titers of the Ts88 immune sera and the antigenicity of the recombinant protein were detected by ELISA and Western blotting. Immuno-fluorescence test was performed in order to confirm the distribution of Ts88 protein in the worm. RESULTS: The fragment of Ts88 gene was expressed successfully in E. coli and a highly purified fusion protein was obtained. Immunization with the recombinant protein in mice produced high titers of antibodies, which recognized some components of native antigens of soluble proteins from adult worm of T. spiralis. Western blotting analysis showed that Ts88 recombinant antigen was recognized by all the positive sera, such as the sera from infected or immunized rabbits, from infected swine and from patients of trichinosis. Immuno-fluorescence test confirmed that Ts88 protein mainly distributed in the cuticle surface of the worm. CONCLUSION: The Ts88 antigen gene from T. spiralis was successfully expressed. The recombinant protein presented antigenicity.

Animals↗

PubMed2003

Expression of Clara cell secretory protein in the lungs of rats exposed to silicon carbide whisker in vivo.

Intratracheal instillation studies have shown that exposure to silicon carbide whiskers (SiCW), an asbestos substitute, produces pulmonary fibrotic changes, suggesting that SiCW might have fibrogenic potential. It has been theorized that Clara cell secretory protein (CCSP) plays a critical role in regulating the acute inflammatory response in the lung. The present study was conducted to investigate the time course of the expression of CCSP in lungs exposed to SiCW in vivo. Male Wistar rats were administered 2 mg or 10 mg of SiCW suspended in saline by a single intratracheal instillation and were sacrificed at 3 days, 1 week, 1 month, 3 months and 6 months of recovery time. The expression of CCSP was observed by reverse transcriptase-polymerase chain reaction (RT-PCR), Western blot and immunostaining. Exposure to 10 mg of SiCW decreased in levels of CCSP mRNA at 3 days, 1 week, 1 month and 6 months following intratracheal instillation. The protein level of CCSP in SiCW-exposed rats was decreased at 1 day, 3 days and 1 month after a single instillation of 2 and 10 mg. These findings suggest that CCSP are involved not only in the acute injury but also in the chronic injury of the lung exposed to SiCW.

Animals↗

PubMed2003

The expression of Smads and transforming growth factor beta receptors in leiomyoma and myometrium and the effect of gonadotropin releasing hormone analogue therapy.

Gene microarray analysis indicated that several components of the transforming growth factor beta receptor (TGF-betaR) signaling pathway are differentially expressed in leiomyoma and myometrium. To validate the microarray results we evaluated the expression of Smads, intracellular proteins that transmit TGF-betaR signals, in leiomyoma and matched myometrium from untreated women, and women who received gonadotropin releasing hormone analogue (GnRHa) therapy. Semi-quantitative RT-PCR, Western blotting and immunohistochemistry indicate that leiomyoma and myometrium expresses receptor-activated Smad3, common Smad4 and inhibitory Smad7, with elevated expression of Smad3, Smad4 and phosphorylated Smad3 (pSmad3) as well as TGF-betaR type I and type II in leiomyoma compared to myometrium (P<0.05). GnRHa therapy resulted in lowering of TGF-betaRs as well as Smad4 and pSmad3, with concurrent increased in Smad7 expression in both leiomyoma and myometrium compared to untreated group (P<0.05). Immunohistochemically Smads and pSmad3 were localized in cytoplasmic/nuclear compartments of leiomyoma and myometrial smooth muscle cells and connective tissue fibroblasts, with alteration in their intensity (HScores) in GnRHa-treated group. In conclusion, the results indicates that leiomyoma and myometrium express all the components of TGF-betaR and Smads, and GnRHa therapy results in alteration of their expression further supporting the importance of TGF-beta system as key regulator of leiomyoma growth.

DNA-Binding Proteins↗

PubMed2003

Gold catalysis: efficient synthesis and structural assignment of jungianol and epi-jungianol.

Starting from 2-methylfuran and crotonaldehyde, both jungianol and epi-jungianol were prepared by a six-step sequence including a gold-catalyzed arene synthesis and a photochemical S(N)2-like reduction with lithium aluminum hydride. Not a single protective group was needed in the entire synthesis. With both diastereomers in hand, the stereochemical assignment in the literature could be corrected by means of a thorough (1)H NMR spectroscopic analysis and an X-ray diffraction study on an epi-jungianol derivative.

Catalysis↗

PubMed2003

Analysis of plasmid samples on a microchip.

We have developed a LabChip-based plasmid assay that runs on the Agilent 2100 Bioanalyzer. The assay determines the sizes and relative concentrations of the multiple forms of plasmid samples. Twelve samples can be analyzed on each chip in an automated run lasting approximately 30min. By using a supercoiled DNA sizing standard of 2-16kb, the size of the analyzed plasmid can be determined. The resulting MW has a relative standard deviation (CV) <5% and error <5%. Plasmids from 2-8kb can be separated with resolution better than 1kb. Topological isoforms in a plasmid sample can also be separated. However, due to differential staining, the heterogeneity of plasmid samples can only be measured if the signal of each isomer peak can be calibrated with pure standards for every isomer form. For a typical plasmid preparation which predominately is in the supercoiled form, the normalized corrected peak area for the supercoiled form correlates with the plasmid concentration in a broad range of 1-100ng/microl. The measurement is semiquantitative with a CV lower than 20%. A number of applications of this assay on a Labchip will be shown.

Chemistry Techniques, Analytical↗

PubMed2003

Severe phenotype of chronic granulomatous disease presenting in a female with a de novo mutation in gp91-phox and a non familial, extremely skewed X chromosome inactivation.

Chronic granulomatous disease (CGD) is an inherited immunodeficiency resulting from defects in the multienzyme complex NADPH-oxidase (phagozyte oxidase, phox), which normally produces microbicidal reactive oxygen metabolites (ROM). The reason for our patient's CGD was unusual, as revealed by the following in vitro findings in neutrophils and EBV-transformed B-cells: lack of flavocytochrome b(558) expression, restoration of significant ROM production after transduction with gp91-phox cDNA by a retrovirus vector, an 879G-->A, Trp289-->Stop mutation in one X chromosomal gp91-phox allele, a one-sided paternal X chromosome inactivation, as shown by a lyonization assay at the HUMARA locus, and the result of a dihydrorhodamine 123 flow cytometry assay revealing consistently that 1 in 2500 neutrophils produced ROM at normal levels. Our conclusion: A presumed autosomal form of CGD has been excluded. Instead, a spontaneous mutation in gp91-phox coinciding with an extreme X chromosome inactivation ratio resulted in X-linked CGD in this young woman.

Adult↗

PubMed2003

Effect of complement fragment 1 esterase inhibition on survival of human decay-accelerating factor pig lungs perfused with human blood.

BACKGROUND: The role of complement in hyperacute lung xenograft rejection has not been fully elucidated. The present study evaluates the effect of complement (C) 1 esterase inhibition on hyperacute rejection of human decay-accelerating factor (hDAF)-positive pig lung by human blood. METHODS: Using a modification of an established ex vivo model, right and left lungs from individual animals were surgically isolated and separately perfused. Pigs homozygous for hDAF were perfused with fresh human blood that was either untreated or treated with complement 1 esterase inhibitor (C1-Inh) at doses of 1 U/ml (n = 5), 5 U/ml (n = 3) or 10 U/ml plasma (n = 5). RESULTS: Only C1-Inh at 10 U/ml prolonged survival time (230 +/- 48.3 minutes) as compared with controls (65.6 +/- 26.5 minutes, p < 0.05) and diminished complement activation (C3a and C5a, p < 0.05). Interestingly, a low concentration of C1-Inh increased the pulmonary vascular resistance (PVR; 1 U/ml: 0.54 +/- 0.3; 10 U/ml: 0.19 +/- 0.08). Sequestration of neutrophils (92 +/- 3%) and platelets (64 +/- 13%) was not prevented by any concentration of C1-Inh. Tissue deposition of C3b and C5b-9 were diminished by hDAF expression, and further blunted by treatment, with 10 U/ml C1-Inh. CONCLUSIONS: Complement plays a critical role in early events of lung hyperacute rejection (HAR). However, even potent inhibition of C1 esterase and C3/C5 convertase, using serum C1-Inh in pig lungs homozygous for hDAF expression, does not prevent rapid lung injury. Our findings implicate innate immune pathways resistant to efficient complement regulation, and suggest a role for neutrophils and platelets in the lung's particular vulnerability.

Animals↗

PubMed2003

Self-assembly is important for TIP47 function in mannose 6-phosphate receptor transport.

TIP47 (tail-interacting protein of 47 kDa) binds to the cytoplasmic domains of mannose 6-phosphate receptors and is required for their transport from endosomes to the trans-Golgi network in vitro and in living cells. TIP47 occurs in cytosol as an oligomer; it chromatographs with an apparent mass of approximately 300 kDa and displays an S-value of approximately 13. Recombinant TIP47 forms homo-oligomers that are likely to represent hexamers, as determined by chemical cross-linking. Removal of TIP47 residues 1-151 yields a protein that behaves as a monomer upon gel filtration, yet is fully capable of binding mannose 6-phosphate receptor cytoplasmic domains. The presence of an oligomerization domain in the N-terminus of TIP47 was confirmed by expression of N-terminal residues 1-133 or 1-257 in mammalian cells. Co-expression of full-length TIP47 with either of these fragments led to the formation of higher-order aggregates of wild-type TIP47. Furthermore, the N-terminal domains expressed alone also occurred as oligomers. These studies reveal an N-terminal oligomerization domain in TIP47, and show that oligomerization is not required for TIP47 recognition of mannose 6-phosphate receptors. However, oligomerization is required for TIP47 stimulation of mannose 6-phosphate receptor transport from endosomes to the trans-Golgi in vivo.

Animals↗

PubMed2003

Validation of dynamic MLC-controller log files using a two-dimensional diode array.

Intensity-modulated radiation therapy (IMRT) delivered with multi-leaf collimator (MLC) in the step-and-shoot mode uses multiple static MLC segments to achieve intensity modulation. For typical IMRT treatment plans, significant numbers of segments are delivered with monitor units (MUs) of much less than 10. Verification of the ability of the linear accelerator (linac) to deliver small MU segments accurately is an important step in the IMRT commissioning and quality assurance (QA) process. Recent studies have reported large discrepancies between the intended and delivered segment MUs. These discrepancies could potentially cause large errors in the delivered patient dose. We have undertaken a systematic study to evaluate the accuracy of the dynamic MLC log files, which are created automatically by our commercial MLC workstation after each delivery, in recording the fractional MU delivered in the step-and-shoot mode. Two linac models were evaluated with simple-geometry leaf sequences and delivered with different total MUs and different nominal dose rates. A commercial two-dimensional diode array was used for the measurement. Large discrepancies between the intended and delivered segment MUs were found. The discrepancies were larger for small MU segments at higher dose rate, with some small MU segments completely undelivered. The recorded fractional MUs in the log files were found to agree with what was delivered within the limits of our experimental uncertainty. Our results indicate that it is important to verify the delivery accuracy of small MU segments that could potentially occur in a patient treatment and that the log files are useful in checking the integrity of the linac delivery once validated. Thus validated log files can be used as a QA tool for general IMRT delivery and patient-specific plan verification.

Documentation↗

PubMed2003

Phagocyte NADPH oxidase, but not inducible nitric oxide synthase, is essential for early control of Burkholderia cepacia and chromobacterium violaceum infection in mice.

Reactive oxygen and nitrogen intermediates have critical, partially overlapping roles in host defense against a variety of pathogens. Using mice deficient in generating phagocyte superoxide (p47(phox)(-/-)) and mice deficient in generating inducible nitric oxide synthase (iNOS(-/-)), we examined the roles of these reactive species in host defense against Burkholderia cepacia and Chromobacterium violaceum, organisms known to have unusual virulence in chronic granulomatous disease. Intraperitoneal B. cepacia challenge (4.0 x 10(3) to 4.0 x 10(5) organisms/mouse) resulted in mortality in all p47(phox)(-/-) mice, with the survival interval being inversely proportionate to the amount of inoculum. Pretreatment with gamma interferon did not affect survival. C. violaceum was strikingly virulent in p47(phox)(-/-) mice (the 50% lethal dose [LD(50)] was <13 organisms). iNOS(-/-) and wild-type mice were resistant to B. cepacia challenges of at least 10(6) organisms per mouse, and the LD(50) of C. violaceum was between 10(6) and 10(7) organisms per mouse. Consistent with the survival data, numbers of organisms in cultures of B. cepacia from multiple sites were higher for p47(phox)(-/-) mice than for iNOS(-/-) and wild-type mice at day 4 after challenge, but numbers of organisms for different B. cepacia strains varied. The recovery of C. violaceum was strikingly greater at 18 h after challenge for p47(phox)(-/-) mice than for iNOS(-/-) and wild-type mice, in which the organism burdens were virtually nil. In vitro, both B. cepacia and C. violaceum were sensitive to H(2)O(2) and to reactive nitrogen intermediates but the sensitivities of different strains varied significantly. Host defense against B. cepacia and C. violaceum is critically dependent in vivo on reactive oxygen intermediates, and these species are model organisms to further dissect host and pathogen interactions related to the generation and scavenging of microbicidal reactive intermediates.

Animals↗

PubMed2003

Gene expression of surfactant protein-A and thyroid transcription factor-1 in lungs of rats exposed to silicon-carbide whisker in vivo.

Intratracheal instillation studies have shown that exposure to silicon carbide whisker (SiCW), an asbestos substitute, produces pulmonary fibrotic changes, suggesting that SICW might have a fibrogenic potential. It is thought that surfactant protein is a good biomarker of lung injury and pulmonary fibrotic activity. In order to explore whether or not surfactant protein is associated with lung disorder through exposure to SiCW, we examined the expression of SP-A, SP-C and thyroid transcription factor-1 (TTF-1), a common transcription factor of SP-A and SP-C mRNA in lungs exposed to SiCW. Male Wistar rats were administered 2 mg or 10 mg of SiCW suspended in saline by a single intratracheal instillation, and were sacrificed at 3 d, 1 wk, 1 month, 3 months and 6 months after the intratracheal instillation. RNA was subsequently extracted from the lungs, and expression of SP-A, SP-C and TTF-1 mRNA from the lungs was observed by reverse transcription-polymerase chain reaction (RT-PCR). Exposure to 2 mg of SiCW showed a decrease in mRNA of SP-A and TTF-1 at 6 months, but exposure to 10 mg of SiCW showed decreased levels of SP-A and TTF-1 mRNA at 3 d and 6 months. On the other hand, 2 mg of SiCW increased the level of SP-C mRNA from 3 d to 3 months, and 10 mg of SiCW decreased the levels of SP-C mRNA in the rat lungs at 3 d, 1 month and 6 months. No clear tendency to the expression of SP-C was observed, but the patterns of expression of TTF-1 and SP-A were similar. These data suggest that SP-A and TTF-1 are associated with not only the acute phase but also the chronic phase in lungs exposed to SiCW.

Animals↗

PubMed2003

[Relationship between p53, bax and bcl-2 expression and cell apoptosis in intrahepatic cholestasis of pregnancy].

OBJECTIVE: To investigate the changes of gene p53, bax and bcl-2 expression and to study the role on cell apoptosis in placenta through apoptosis in placenta with intrahepatic cholestasis of pregnancy (ICP). METHODS: TdT-mediated dUTP nick end labeling (TUNEL) and immuno-histochemistry methods were used for 31 placental samples with ICP and 31 normal placental samples to detect apoptosis index and the expression of p53, bax and bcl-2 in placenta tissues. RESULTS: The apoptosis index in placental cytotrophoblast, syncytiotrophoblast, decidual cells and mediate cell on ICP group was significantly higher than that in control group (P < 0.01). The expression of p53 was higher than those of control. Bax expression in syncytoitrophoblast, decidual cell and mediate cell in ICP group was higher (P < 0.01), but the expression of bax in placental cytotrophoblast cell was not significantly higher (P > 0.05). The expression of bcl-2 of these positions in ICP group was lower than that in control group (P < 0.01) p53, bax and bcl-2 expressions in (chi +/- s)% in the syncytoitrophoblast cells of placenta with ICP is 75.9 +/- 8.2, 65.8 +/- 13.8, 45.3 +/- 11.3. CONCLUSION: The placental dysfunction may closely relate to the apoptosis. Abnormal overexpression of p53, bax and the low expression of bcl-2 on placental tissue of ICP was the main reason of placental apoptosis.

Adult↗

PubMed2003

Disseminated trichosporonosis in a murine model of chronic granulomatous disease.

Over a period of ten months, five mice submitted to our service (the Pathology Section of the Veterinary Resources Program, Office of Research Services at the National Institutes of Health, Bethesda, Md.) were diagnosed with disseminated trichosporonosis. These mice had pyogranulomatous inflammation in multiple organs, including lung, liver, lymph nodes, salivary gland, and skin. Fungal elements in many of the lesions were identified, using special histochemical stains, and Trichosporon beigelii was obtained by use of culture of specimens at affected sites. This saprophytic fungus has caused disseminated disease in immunosuppressed humans. However, despite widespread use of immunosuppressed rodents in research, to the authors' knowledge, this organism had not previously been reported to cause spontaneous disseminated disease in laboratory mice. All affected mice had a genetically engineered defect in p47(phox), a critical component of the nicotinamide dinucleotide phosphate (NADPH) oxidase, the enzyme responsible for generating the phagocyte oxidative burst. These animals are used as a murine model of human chronic granulomatous disease. We discuss the lesions, differential diagnosis, identification of the organism, and the role of NADPH oxidase in protecting against disseminated trichosporonosis.

Animals↗

PubMed2003

[Bioequivalence of donepezil capsule and tablet in human].

AIM: To develop an HPLC-MS assay for determination of donepezil in human plasma and to investigate the pharmacokinetics and bioequivalence of donepezil capsule in healthy volunteers. METHODS: A randomized crossover design was performed in 20 healthy volunteers. In the two study periods, a single 5 mg dose of either capsule or tablet was administered to each volunteer. After spiked with the internal standard (phenoprolamine) and treated with saturated sodium bicarbonate, plasma was extracted with ethyl acetate and separated with a C18 reversed phase column. LC-ESIMS was used in the selected ion monitoring (SIM) mode with target ions at m/z 380 for donepezil and m/z 344 for phenoprolamine. The fragmentor voltage was 120 V. The main pharmacokinetic parameters of donepezil and the bioequivalence of its two preparations were calculated. RESULTS: The main pharmacokinetic parameters T1/2, Tmax and Cmax were (63 +/- 10) h, (3.3 +/- 0.4) h and (8.5 +/- 0.4) microgram.L-1 for the capsule; (57 +/- 9) h, (3.4 +/- 1.0) h and (8.1 +/- 1.0) microgram.L-1 for the tablet, respectively. The relative bioavailability of the donepezil capsule was 102% +/- 11%. CONCLUSION: The assay was shown to be sensitive, accurate and convenient. The two preparations of donepezil were bioequivalent.

Adult↗

PubMed2003

[Determination of finasteride in human plasma by HPLC-MS].

AIM: To develop an HPLC-MS assay for determination of finasteride in human plasma and to investigate the bioequivalence in healthy volunteers. METHODS: After alkalization with sodium hydroxide, plasma was extracted with ethyl acetate and separated using a C18 column with a mobile phase of methanol-water (85:15). LC-ESI-MS was performed in the selected ion monitoring (SIM) mode using target ions at m/z 395 for finasteride and m/z 407 for the IS. The fragmentor voltage was 120 V. A randomized crossover design was performed in 20 healthy volunteers. In the two study periods, a single 10 mg dose of each tablet was administered to each volunteer. RESULTS: Calibration curves were linear over the range 1-200 micrograms.L-1 (r = 0.9986). The limit of determination for finasteride in plasma was 0.05 microgram.L-1. The recovery of finasteride from plasma was in the range of 85.9%-98.7%. The results of variance analysis and two one-side t-test showed that there was no significant difference between the two formulations in the AUC and Cmax. CONCLUSION: The assay was proved to be sensitive, accurate and convenient. The two formulations were bioequivalent.

Adult↗

PubMed2002

Protein kinase C-epsilon promotes survival of lung cancer cells by suppressing apoptosis through dysregulation of the mitochondrial caspase pathway.

The serine/threonine protein kinase C (PKC) has been implicated in the regulation of drug resistance and cell survival in many types of cancer cells. However, the one or more precise mechanisms remain elusive. In this study, we have identified and determined the mechanism by which PKC-epsilon, a novel PKC isoform, modulates drug resistance in lung cancer cells. Western blot analysis demonstrates that expression of PKC-epsilon, but not other PKC isoforms, is associated with the chemo-resistant phenotype of non-small cell lung cancer (NSCLC) cell lines. Northern blotting and nuclear run-on transcription analysis further reveals that the failure of expression of PKC-epsilon in the chemo-sensitive phenotype of small cell lung cancer (SCLC) cells results from transcriptional inactivation of the gene. Importantly, forced expression of PKC-epsilon in NCI-H82 human SCLC cells confers a significant resistance to the chemotherapeutic drugs, etoposide and doxorubicin. Resistance is characterized by a significant reduction in apoptosis in PKC-epsilon-expressing cells. Treatment of NCI-H82 cells with etoposide induces a series of time-dependent events, including the release of cytochrome c from the mitochondria to the cytosol, activation of caspase-9 and caspase-3, and cleavage of poly(ADP-ribose) polymerase (PARP). All of these events are blocked by PKC-epsilon expression. Furthermore, caspase-specific inhibitors, z-VAD-fmk and z-DEVD-fmk, significantly attenuate the accumulation of sub-G(1) population and block the PARP cleavage in response to etoposide. These results suggest that PKC-epsilon prevents cells from undergoing apoptosis through inhibition of the mitochondrial-dependent caspase activation, thereby leading to cell survival. Finally, down-regulation of PKC-epsilon expression by the antisense cDNA in NSCLC cells results in increased sensitivity to etoposide. Taken together, our findings suggest an important role for PKC-epsilon in regulating survival of lung cancer cells.

Antineoplastic Agents↗

PubMed2002

Thioglycollate peritonitis in mice lacking C5, 5-lipoxygenase, or p47(phox): complement, leukotrienes, and reactive oxidants in acute inflammation.

Leukotriene B(4) (LTB(4)) is an easily diffusible proinflammatory chemotactic factor that has been posited to prime the initial inflammatory response for the action of other mediators, including C5a. 5-Lipoxygenase-deficient (5LX(-/-)) and C5-deficient mice only generated about 50% as much peritoneal leukocytosis as wild-type mice following intraperitoneal (IP) challenge with the sterile irritant, thioglycollate (P<0.005). Pretreatment of C5- mice with the specific 5-lipoxygenase inhibitor, zileuton, reduced peritoneal leukocytosis to almost unstimulated levels, suggesting that LTB(4) can act independently of C5a. Previously, LTB(4) and C5a have been shown in vitro to be inactivated by metabolites of superoxide. In the current study, we examined the fate of LTB(4) in the p47(phox-/-) mouse model of chronic granulomatous disease (CGD) in which the phagocyte NADPH oxidase is unable to produce superoxide. p47(phox-/-) mice generated more thioglycollate-elicited peritoneal leukocytosis than wild-type mice. Pretreatment with zileuton caused a 76% reduction in peritoneal leukocytosis in p47(phox-/-) mice (P<0.005) and a 54% reduction in wild-type mice (P<0.05), whereas pretreatment with dexamethasone or toradol (a cyclooxygenase inhibitor) had no effect. Following IP LTB(4) (1 microg/mouse), total recovered peritoneal LTB(4) was similar between p47(phox-/-) and wild-type mice at 10 and 30 min, but was approximately fivefold greater in p47(phox-/-) mice at 180 min. These data suggest that LTB(4) and C5a have separate but overlapping roles in thioglycollate-elicited peritonitis, and at least the leukotriene component is, in turn, regulated by reactive oxidants.

Animals↗

PubMedDate not supplied

Rapid and sensitive liquid chromatography-electrospray ionization-mass spectrometry method for the determination of eperisone in human plasma: method and clinical applications.

A sensitive liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) method for determination of eperisone in human plasma using buflomedil as the internal standard (IS) is established. After being made alkaline with saturated sodium bicarbonate solution, plasma samples are extracted with a mixture of diethyl ether-cyclohexane (1:1, v/v) and separated by high-performance liquid chromatography on a reversed-phase C(18) column with a mobile phase of 10mM ammonium acetate buffer (adjusted the pH to 3.9 with acetic acid)-methanol (20:80, v/v). Eperisone is determined using ESI in a single-quadrupole MS. LC-ESI-MS is performed in the selected ion monitoring mode using target ions at m/z 260 for eperisone and m/z 308 for the IS. Calibration curves are linear over the ranges 0.02-20 ng/mL for eperisone. The intra- and interassay variability values are less than 9.0% and 11.5%, respectively. The mean plasma extraction recovery of eperisone is 91.7 +/- 6.6%. The method has been successfully applied to study the pharmacokinetics of eperisone in healthy, male, Chinese volunteers. Pharmacokinetic parameters of the reference and test tablets have been compared.

Chromatography, High Pressure Liquid↗