Influence of SiRNA Targeting Survivin on Chemosensitivity of H460/cDDP Lung Cancer Cells

We investigated the difference in survivin expression between a multidrug-resistant lung cancer cell line (H460/cDDP) and its parental counterpart (H460) and the influence of siRNA targeting survivin on the chemosensitivity of H460/cDDP. SiRNA targeting survivin was transfected into H460/cDDP cells using a liposome approach. Survivin mRNA and protein expression were significantly higher in H460/cDDP than H460 cells. The median inhibitory concentrations (IC50s) for cisplatin and paclitaxol in vitro against H460/cDDP cells were significantly lower in cells treated with survivin-specific siRNA than in control cells. Apoptosis and cleaved caspase-3 expression were analysed using annexin V and Western blotting, respectively, and showed a significant increase in apoptosis after treatment with the chemotherapeutic agents plus specific siRNA. Specific siRNA sensitized H460/cDDP cells to both cisplatin and paclitaxol. Thus, survivin appears to participate in the multidrug resistance mechanism of H460/cDDP cells and siRNA targeting survivin has the potential to increase the sensitivity of drug-resistant cancer cells to anticancer drugs.

Size-exclusion chromatography with on-line light scattering

This unit describes the use of size-exclusion chromatography with on-line light scattering, UV absorbance, and refractive index detectors (SEC-LS/UV/RI) to determine: (a) the molecular weight of simple proteins containing no carbohydrates, (b) the molecular weight of glycoproteins, and (c), most importantly, the molecular weight and stoichiometry of protein-protein complexes or protein-carbohydrate complexes. Multiangle light scattering is also discussed.

Overexpression of cyclooxygenase-2 is associated with chemoradiotherapy resistance and prognosis in esophageal squamous cell carcinoma patients

Our objective was to investigate whether cyclooxygenase-2 (COX-2) expression can predict the patient's response to chemoradiotherapy (CRT) and ensuing prognosis in esophageal squamous cell carcinoma (ESCC). The clinicopathological and follow-up data of 112 patients with ESCC who underwent CRT from January 2001 to June 2006 were analyzed retrospectively. The immunohistochemical expression level of COX-2 was examined for all biopsy specimens of primary tumors, and the correlation of COX-2 expression with the patient's response to CRT and prognosis was examined. COX-2 positive immunostaining was detected in 111 (99.1%) of the patients, including overexpression in 54 (48.2%) patients and low expression in 58 (51.8%) of the patients. The response of tumors with a low level expression of COX-2 (70.7%, 41/58) was significantly higher than that of tumors with COX-2 overexpression (42.6%, 23/54; P = 0.003). Patients with a low level of COX-2 expression had a higher downstaged rate than those with a high level of COX-2 expression (9/13 vs 2/8), but the difference was not statistically significant (P = 0.08). In the definitive CRT group (91 cases), COX-2 overexpression was significantly associated with poor 3-year overall survival (P = 0.028). Multivariate analysis showed that only metastatic stage (nonregional node metastasis) was an independent prognosis factor. The assessment of COX-2 status may provide additional information to identify ESCC patients with poor chances of response to CRT and potential candidates for more individualized treatment.

Topology preserving non-negative matrix factorization for face recognition

In this paper, a novel topology preserving non-negative matrix factorization (TPNMF) method is proposed for face recognition. We derive the TPNMF model from original NMF algorithm by preserving local topology structure. The TPNMF is based on minimizing the constraint gradient distance in the high-dimensional space. Compared with L(2) distance, the gradient distance is able to reveal latent manifold structure of face patterns. By using TPNMF decomposition, the high-dimensional face space is transformed into a local topology preserving subspace for face recognition. In comparison with PCA, LDA, and original NMF, which search only the Euclidean structure of face space, the proposed TPNMF finds an embedding that preserves local topology information, such as edges and texture. Theoretical analysis and derivation given also validate the property of TPNMF. Experimental results on three different databases, containing more than 12,000 face images under varying in lighting, facial expression, and pose, show that the proposed TPNMF approach provides a better representation of face patterns and achieves higher recognition rates than NMF.

Cryoablation induces necrosis and apoptosis in lung adenocarcinoma in mice

This study evaluated cryoablation on subcutaneously transplanted tumors of lung adenocarcinoma LA795 in T739 mice in vivo, in an effort to assess the feasibility of cryoablation in treatment of NSCLC. Subcutaneously transplanted lung adenocarcinoma LA795 was implanted into T739 mice yielding tumors of approximately 2.5 cm in diameter. Following cryoablation, the various modes of cell death were studied: necrosis in the central frozen zone by light microscopy and apoptosis in periphery of the frozen zone by in situ end labeling (TUNEL). Bc1-2 and bax expression were detected by immunohistochemical SABC procedures, and the cleavage and activation of Caspase 3 and PARP in peripheral zone by Western blot. We find that in central cryoablated zone, necrosis was the dominant mode of cell death occurring at three hours and four days post-thaw. The first three-hour necrosis peak involved approximately 47% of the tumor while the four-day peak increased in volume to 68% of the tumor. In peripheral cryoablation zone, definite cell apoptosis could be observed by morphological examination under light microscope and TUNEL staining, peaking at 8-16 h after cryoablation. Immunohistochemical results yielded little change in bcl-2 protein expression before and after cryoablation. However, bax protein expression was up-regulated significantly after cryoablation. In addition, cleavage and activation of Caspase-3 and PARP occurred in the peripheral freeze zone after the treatment. It indicated that Cryoablation efficiently induces cell death both by necrosis and apoptosis. Cryoablation appears to induce apoptosis in the peripheral freeze zone through the intrinsic mitochondrial caspase pathway based on bax upregulation. This observation allows us to suggest that cryoablation may be combined with chemotherapy to increase cancer destruction.

Manual versus electric vacuum aspiration for first-trimester abortion: a systematic review

BACKGROUND

As an alternative to electric vacuum aspirations (EVA), there is an increasing interest in using manual vacuum aspiration (MVA).

OBJECTIVE

To compare the safety, efficacy and acceptability of MVA with those of EVA for first-trimester abortion.

SEARCH STRATEGY

We searched MEDLINE, EMBASE, Cochrane Library and Chinese Biomedical Database in all language, together with reference lists of retrieved papers.

SELECTION CRITERIA

Randomised controlled trials comparing MVA with EVA for first-trimester abortion were included. The outcomes are complete abortion rate, uterine perforation rate, blood loss, pain perception and acceptability.

DATA COLLECTION AND ANALYSIS

Two reviewers independently extracted the data. Results from the trials were combined to calculate relative risks (RRs) or risk differences for dichotomous outcomes and weighted mean differences (WMDs) for continuous outcomes, together with 95% CIs.

MAIN RESULTS

Ten trials were included, involving 1660 women. Generally, the methodological quality was poor. There were no statistically significant differences, comparing MVA with EVA, in complete abortion rate (RR 1.00; 95% CI 0.99-1.02) and participants' satisfaction (RR 1.02; 95% CI 0.87-1.20). In participants with less than 50 days of gestational age, less blood loss (WMD -1.84; 95% CI -2.45 to -1.23) and less severe pain perception (RR 0.04; 95% CI 0.01-0.12) were reported during the MVA procedure, whereas the operation time was shorter (WMD 0.32; 95% CI 0.02-0.63) in the EVA procedure.

AUTHOR'S CONCLUSIONS

There is some evidence that MVA is as effective and acceptable as EVA and might be safer than EVA.

Effect of chronic heat exposure on fat deposition and meat quality in two genetic types of chicken

The effects of chronic heat stress on growth, proportion of carcass and fat deposition, and meat quality were investigated in 2 genetic types of chickens. One hundred and eight 5-wk-old male chickens from a commercially fast-growing strain (Arbor Acres, AA) and a locally slow-growing species (Beijing You chicken, BJY) were kept in the following conditions: constant optimal ambient temperature at 21 degrees C and ad libitum feeding (21AL), constant high ambient temperature at 34 degrees C and ad libitum feeding (34AL), and constant optimal ambient temperature 21 degrees C and pair-fed to the 34AL chickens (21PF). The results showed that feed intakes were decreased by heat exposure in both type of chickens at 8 wk of age (P<0.001). At 34 degrees C, AA broilers exhibited greatly decreased weight gain (22.38 vs. 61.45 g/d for 21AL) and lower breast proportion compared with 21AL, while the relevant indices of BJY chickens were not affected in hot condition. Abdominal fat deposition of BJY chickens was enhanced by heat exposure (P<0.05). Fat deposition of AA broilers was decreased in heat-exposed and pair-fed chickens. Abdominal and intermuscular fat deposition in 34AL birds, however, were enhanced compared with 21PF birds (P<0.01). The L* values, drip loss, initial pH, and shear force of breast meat in BJY chickens were not affected by treatments. In AA birds, chronic heat stress increased L* values and drip loss compared with 21AL, but pH and shear force were not affected by treatments. The results from this study indicated that the impact of heat stress was breed dependent and that BJY chickens showed higher resistance to high ambient temperature, which could be related to their increased feed efficiency and deposition of abdominal fat under heat exposure.

Mutation of superoxide dismutase elevates reactive species: comparison of nitration and oxidation of proteins in different brain regions of transgenic mice with amyotrophic lateral sclerosis

As part of our effort to study the role of reactive species in amyotrophic lateral sclerosis (ALS), the goal of this work is to explore the correlation between nitration and oxidation of proteins and mutation of Cu, Zn-superoxide dismutase (SOD1) in ALS. Transgenic mice overexpressing the mutant Cu, Zn-superoxide dismutase (mSOD1) gene from humans with familial ALS, wild-type mice overexpressing the normal human SOD1 gene and normal mice without gene overexpression were used. Brain sections from different regions of three groups of mice were double immunohistochemically stained with anti-neurofilament plus anti-nitrotyrosine or treated with 2,4-dinitrophenylhydrazine to label protein carbonyls, then double stained with anti-neurofilament plus anti-2,4-dinitrophenyl (anti-DNP). Neurons containing nitrated and oxidized proteins were visualized only in mSOD1 mice in the motor cortex, the cerebellar cortex and nucleus of hypoglossal nerves (regions related with movement). This correlates mutation of SOD1 to nitration and oxidation of neurons in the movement regions. By counting double-stained neurons, we demonstrated that the number of nitrotyrosine- and DNP-positive neurons was significantly higher in the brain sections of both motor and sensory cortex in mSOD1 mice than in the corresponding regions of control mice (P=0.005 to <0.001), further correlating nitration and oxidation of proteins to SOD1 mutation. Neurons underwent significantly more nitration and oxidation in the motor cortex than in the sensory cortex in mSOD1 mice (P=0.002 and 0.02 respectively), indicating enhanced susceptibility of the motor cortex to nitration and oxidation of proteins and thereby targeting oxidation and nitration of proteins in neurons of the motor cortex in ALS. Significantly elevated protein nitration and nitric oxide synthesis were also demonstrated biochemically in the brain tissues and in cerebrospinal fluid of mutant SOD1 mice. Our in vivo evidence correlates mutation of the SOD1 gene to increased nitric oxide, nitration and oxidation of proteins in ALS.

Polyamorphism in a metallic glass

A metal, or an alloy, can often exist in more than one crystal structure. The face-centred-cubic and body-centred-cubic forms of iron (or steel) are a familiar example of such polymorphism. When metallic materials are made in the amorphous form, is a parallel 'polyamorphism' possible? So far, polyamorphic phase transitions in the glassy state have been observed only in glasses involving directional and open (such as tetrahedral) coordination environments. Here, we report an in situ X-ray diffraction observation of a pressure-induced transition between two distinct amorphous polymorphs in a Ce(55)Al(45) metallic glass. The large density difference observed between the two polyamorphs is attributed to their different electronic and atomic structures, in particular the bond shortening revealed by ab initio modelling of the effects of f-electron delocalization. This discovery offers a new perspective of the amorphous state of metals, and has implications for understanding the structure, evolution and properties of metallic glasses and related liquids. Our work also opens a new avenue towards technologically useful amorphous alloys that are compositionally identical but with different thermodynamic, functional and rheological properties due to different bonding and structural characteristics.

High prevalence of albuminuria in population-based patients diagnosed with type 2 diabetes in the Shanghai downtown

OBJECTIVE

The prevalence of albuminuria and the risk factors associated with albuminuria were evaluated among the Chinese patients diagnosed with type 2 diabetes aged over 30 in the Shanghai downtown. We also evaluated the variability of urinary albumin-to-creatinine ratio (ACR) among the three measurements and the relationship between diabetic retinopathy (DR) and albuminuria.

METHODS

The 1039 Chinese patients diagnosed with type 2 diabetes aged over 30 were investigated by randomized cluster sampling in the Shanghai downtown and 1018 patients were analyzed in this study. Body mass measurements including height, weight, waist circumference and hip circumference, resting blood pressure, fasting blood measures, urinary ACR and the digitally stored fundus images were investigated. The prevalence of albuminuria was calculated and the risk factors associated with albuminuria were evaluated by stepwise logistic regression. The concordance of urinary ACR was evaluated by observed agreement. The relationship between albuminuria and DR was also evaluated.

RESULTS

(1) The mean age of all patients was 66.10+/-11.54 years and the duration of diabetes was 7.89+/-7.16 years. (2) The prevalence of albuminuria was 49.6% among the Chinese patients diagnosed with type 2 diabetes aged over 30 in the Shanghai downtown, 41.4% with microalbuminuria and 8.2% with macroalbuminuria. (3) Microalbuminuria was significantly associated with systolic blood pressure, gender and waist circumference. Macroalbuminuria was significantly associated with systolic blood pressure and duration of diabetes. (4) Observed agreement among the three urinary ACR measurement for albuminuria staging was 73.3% (first versus second), 64.5% (first versus third) and 77.5% (second versus third). Observed agreement in the albuminuria staging between the single urinary ACR measurement and all three urinary ACR measurements was 85.8% (first versus all three), 87.6% (second versus all three) and 81.9% (third versus all three). (5) The percentage of DR in the macroalbuminuric group (59.2%) was significantly higher than that in the normalbuminuria group (16.1%) and microalbuminuria group (24.6%). (6) The macroalbuminuric patients with DR had significantly increased fasting blood glucose and HbA1c compared with the macroalbuminuric patients without DR.

CONCLUSION

The prevalence of microalbuminuria observed in the Chinese patients diagnosed with type 2 diabetes aged over 30 in the Shanghai downtown reached up to 41.4% though the observations in our study might be representative of the diabetic patients of the Shanghai downtown. We agreed that at least two of the three urinary collections were done in a 3- to 6-month period because of the day-to-day variability in albumin excretion. The percentage of DR among the patients with macroalbuminuria was 59.2%, and the macroalbuminuric patients with the significantly high plasma glucose and DR were prone to diagnose DN.

Expression of zinc-fingers and homeoboxes 2 in hepatocellular carcinogenesis: a tissue microarray and clinicopathological analysis

Zinc-fingers and homeoboxes 2 (ZHX2) is a novel transcriptional repressor. ZHX2 protein expression and its clinicopathological significance in hepatocellular carcinoma (HCC) remain largely unknown. The aim of this study was to analyze ZHX2 protein expression in a range of liver tissues obtained from cholangitis, cirrhosis, adjacent non-tumorous tissues, primary HCC tissues, and matched metastatic lesions by using Tissue microarray (TMA) technology and compare our findings with clinicopathological parameters. ZHX2 protein expression was detected only in HCC tissues. ZHX2 expression was associated with clinical stage of the disease. The rate of ZHX2 expression was approximately twice as high in stage III-IV (31.25%) compared with stage I-II (16.5%). These results demonstrated that ZHX2 protein may take part in hepatocellular carcinogenesis and HCC progression. In addition, ZHX2 expression in primary lesions with metastasis was significantly higher than without metastasis. ZHX2 expression in metastatic lesions (45.5%) was as approximately twice as higher than that in primary lesions (24.2%) from the same patient. According to these results, ZHX2 was associated with metastasis in HCC.

High performance liquid chromatographic determination of a new antifungal compound, ADKZ in rat plasma

A high performance liquid chromatography (HPLC) method was developed and validated for the determination of ADKZ (1-(1H-1,2,4-triazole)-2-(2,4-diflurophenyl) -3-[N-methyl-N-(4-iodo-benzyl)amino]-2-propanol) in rat plasma. The compound was extracted from plasma samples by liquid-liquid extraction, and an isomeric compound of ADKZ (1-(1H-1,2,4-triazole)-2-(2,4-diflurophenyl)-3-[N-methyl-N -(3-iodo-benzyl)amino]-2-propanol) was used as the internal standard (IS), which were analyzed on a reversed-phase C18 column (5 microm, 200 mm x 4.6 mm i.d.). The extracted plasma samples were eluted with acetonitrile-0.018 M triethylamine solution adjusted to pH 3.2 with phosphoric acid (35:65, v/v). The effluent was monitored by a UV detector at 230 nm. The retention time of ADKZ was 7.1 min and IS 8.2 min. The calibration curves were linear in the concentration range of 0.02-2.00 microg/ml with the correlation coefficients greater than 0.999. The quantification limit of ADKZ in rat plasma was 0.02 microg/ml. Intra- and inter-day precision ranged from 2.6 to 7.9% and 3.1 to 9.6%, respectively. The extraction recovery from plasma was no less than 80%. No endogenous interferences were observed with either ADKZ or IS. The method has been successfully used to support the pre-clinical pharmacokinetic studies of ADKZ in rats.

Rifampicin plus pyrazinamide versus isoniazid for treating latent tuberculosis infection: a meta-analysis

SETTING

Six trials from Haiti, Mexico, the U.S.A., Brazil, Spain, Zambia and Hong Kong.

OBJECTIVE

To evaluate the efficacy and safety of rifampicin plus pyrazinamide (RZ) vs. isoniazid (INH) for the prevention of tuberculosis (TB) among persons with or without human immunodeficiency virus (HIV) infection.

DESIGN

Meta-analysis of randomised controlled trials (RCTs) and quasi-RCTs that compared RZ for 2-3 months with INH for 6-12 months. Endpoints were development of active TB, severe adverse effects and death. Treatment effects were summarised as risk difference (RD) with 95% confidence intervals (CI).

RESULTS

Three trials conducted in HIV-infected patients and three trials conducted in non-HIV-infected persons were identified. The rates of TB in the RZ group were similar to those in the INH group, whether the subjects were HIV-infected or not (HIV-infected patients: pooled RD = 0%, 95% CI -1-2, P = 0.89; non-HIV-infected persons: pooled RD = 0%, 95% CI -2-1, P = 0.55). There was no difference in mortality between the two treatment groups (HIV-infected patients: pooled RD = -1%, 95% CI -4-2, P = 0.53; non-HIV-infected persons: pooled RD = 0%, 95% CI -1-1, P = 1.00). However, both subgroup analyses showed that a higher incidence of all severe adverse events was associated with 2RZ than INH among non-HIV-infected persons (RD = 29%, 95% CI 13-46, P = 0.0005 vs. RD = 7%, 95% CI 4-10, P < 0.0001).

CONCLUSION

RZ is equivalent to INH in terms of efficacy and mortality in the treatment of latent tuberculosis infection. However, this regimen increases the risk of severe adverse effects compared with INH in non-HIV-infected persons.

Evidence of angiogenesis and microvascular regression in autosomal-dominant polycystic kidney disease kidneys: A corrosion cast study

Autosomal-dominant polycystic kidney disease (ADPKD) accounts for about 10% of all cases of chronic renal failure requiring dialysis. The disease is characterized by proliferation of renal epithelial cells and formation of cysts that expand over years and replace the normal parenchyma of the kidney. As the cysts grow, the volume of the kidney can increase by more than 10-fold, implying that remodeling and expansion of the vasculature must occur to provide oxygenation and nutrition to the cyst cells. Our previous studies support the notion that there is angiogenesis in ADPKD. We report here results from resin casting of ADPKD kidneys vasculature. In this study, the corrosion-casting method was used in conjunction with scanning electron microscopy to study the vascular architecture and the evidence for angiogenesis in ADPKD kidneys. We found a well-defined vascular network around the cysts forming a 'vascular capsule' somewhat similar to that described in avascular leiomyomata. We also found that the normal vascular architecture is lost and replaced by an assortment of capillaries of larger size than those in the normal kidney, mixed with flattened and spiral arterioles, damaged glomeruli, and atresic venules, indicative of regression of the microvasculature. In the same areas, there was capillary sprouting, considered the hallmark of angiogenesis. The present study documents regression changes of the vasculature and confirms the existence of angiogenesis in ADPKD kidneys, and suggests the use of inhibitors of angiogenesis as a possible avenue for the treatment of the disease.

Refractoriness to short day lengths augments tonic and gonadotrophin-releasing hormone-stimulated lutenising hormone secretion

Siberian hamsters (Phodopus sungorus) undergo reproductive involution following exposure to short winter day lengths. Following approximately 20 weeks of exposure to short day (SD) lengths, hamsters become refractory to the inhibitory effects of SD, and reproductive competence is restored in anticipation of spring. The extent to which changes in gonadal steroid-dependent and -independent regulation of gonadotrophin secretion participate in this vernal reactivation of the gonads is not known. This experiment tested whether tonic and gonadotrophin-releasing hormone (GnRH)-stimulated regulation of lutenising hormone (LH) secretion differs between photoresponsive and photorefractory Siberian hamsters. Male hamsters born into long day (LD) lengths were castrated or subjected to a sham-castration surgery at 17 days of age, implanted s.c. with blank or testosterone-filled capsules, and housed in LD or SD thereafter. Baseline LH and LH responses to GnRH (200 ng/kg, s.c) were measured at 14 (photoresponsive) and 40 (photorefractory) weeks of age. Despite lower circulating testosterone concentrations in gonadally regressed SD hamsters on week 14, tonic LH concentrations were comparable among all groups of gonad-intact hamsters on weeks 14 and 40; however, week 14 SD hamsters exhibited significantly higher GnRH-stimulated LH responses. Tonic LH concentrations were indistinguishable among all groups of castrated hamsters bearing empty implants on week 14, but prolonged exposure to LD led to a decrease in resting LH, whereas prolonged exposure to SD resulted in an increase in LH. In castrated hamsters bearing testosterone implants, baseline LH concentrations were comparable in all groups, but GnRH treatment resulted in significantly higher LH concentrations in photorefractory (week 40, SD) hamsters relative to all other groups. The data suggest that the development of photorefractoriness in Siberian hamsters is characterised by enhanced gonadal hormone-independent stimulation of LH secretion, and diminished sensitivity to inhibitory negative-feedback effects of testosterone on LH secretion. Decreases in responsiveness of gonadotrophin secretion to gonadal hormone negative feedback may contribute to the process of photorefractoriness and assist in maintaining the growth of reproductive organs during the process of gonadal recrudescence.

A T-786C polymorphism in 5'-flanking region of the endothelial nitric oxide synthase gene and endothelium-dependent arterial dilation in Type 2 diabetes

OBJECTIVE

Several studies have shown that the T-786C polymorphism in 5'-flanking region of the endothelial nitric oxide synthase (eNOS) gene is associated with coronary artery disease in non-diabetic population. In the present study, we attempted to assess whether the T-786C polymorphism of eNOS gene is associated with endothelial dysfunction Type 2 diabetes.

RESEARCH DESIGN AND METHODS

A total of 162 Type 2 diabetic men were studied. PCR/allele-specific probes were used to analyse the T-786C polymorphism of eNOS gene, and high resolution ultrasound was used to measure brachial artery diameter at rest, after reactive hyperaemia and after sublingual glyceryltrinitrate.

RESULTS

The flow-mediated arterial dilation among subjects with T/C or C/C was 3.73+/-0.50%, which was significantly lower than that in subjects with T/T (4.15+/-0.49%) (P=0.000). On multiple linear regression analysis, the presence of C allele, mean blood pressure, low-density lipoprotein (LDL) and serum lipoprotein (a) [Lp(a)] were independent determinants for reduced endothelium-dependent arterial dilation (R2=0.175, P=0.0021). The flow-mediated arterial dilation in smokers with T/C or C/C was significantly lower than that in smokers with T/T (P<0.001), but not in non-smokers. In addition, the presence of C allele, LDL and Lp(a) were independent determinants for reduced endothelium-dependent arterial dilation (R2=0.258, P=0.0017) in smokers, but not in non-smokers.

CONCLUSION

The C allele of T-786C polymorphism of eNOS gene is a genetic risk factor for endothelial dysfunction in Type 2 diabetic patients, especially among smokers.

Chiral liquid chromatography resolution and stereoselective pharmacokinetic study of tetrahydropalmatine enantiomers in dogs

A selective chiral high performance liquid chromatographic (HPLC) method coupled with achiral column was developed and validated to separate and quantify tetrahydropalmatine (THP) enantiomers in dog plasma. Chromatography was accomplished by two steps: (1) racemic THP was separated from biological matrix and collected on a Kromasil C18 column (150 mmx4.6 mm, 5 microm) with the mobile phase acetonitrile-0.1% phosphoric acid solution, adjusted with triethylamine to pH 6.15 (47:53); (2) enantiomeric separation was performed on a Chiralcel OJ-H column (250 mmx4.6 mm, 5 microm) with the mobile phase anhydrous ethanol. The detection wavelength was set at 230 nm. (+)-THP and (-)-THP were separated with a resolution factor (Rs) of at least 1.6 and a separation factor (alpha) greater than 1.29. Linear calibration curves were obtained over the range of 0.025-4 microg/ml in plasma for each of (+)-THP and (-)-THP (R2>0.999) with a limit of detection (LOD) of 0.005 microg/ml and the recovery was greater than 88% for each enantiomer. The relative standard deviation (R.S.D.) and relative error values were less than 10% at upper and lower concentrations. The method was used to determine the pharmacokinetics of THP enantiomers after oral administration of racemic THP. The results presented herein showed the stereoselective disposition kinetics of THP in dogs and were a further contribution to the understanding of the kinetic behavior of THP analogues.