Controlled release of levonorgestrel from biodegradable poly(D,L-lactide-co-glycolide) microspheres: in vitro and in vivo studies

Poly(D,L-lactide-co-glycolide) (PLG) biodegradable microspheres containing a contraceptive drug, levonorgestrel (LNG), were prepared using both the solvent evaporation method and a modified solvent extraction-evaporation method. The microspheres prepared with the solvent evaporation process had porous surfaces with low product yields and poor encapsulation efficiencies. On the other hand, the microspheres prepared using the modified solvent extraction-evaporation method were nonporous with encapsulation efficiencies close to 100%. In vitro drug release showed the nonporous microspheres had a lower initial burst and a slightly prolonged duration of release than those porous microspheres. In vivo release kinetics of the low burst microspheres were determined by measuring LNG plasma levels after a single intramuscular injection to female rats. At a LNG dose of 41.1 mg/kg, average plasma LNG levels were 6-10 ng/ml in the first 24 h and subsequently remained above 1 ng/ml until 126 days. The duration above the minimum effective LNG plasma level of 0.2 ng/ml was 168 days. By comparison, a similar dose of LNG microcrystals used as control produced a much higher plasma level of 15-21 ng/ml in the first day followed by a fast and continuous decline of LNG levels with a duration of only about 35 days.

Low molecular weight polyethylenimines linked by β-cyclodextrin for gene transfer into the nervous system

BACKGROUND

Polyethylenimines (PEIs) with high molecular weights are effective nonviral gene delivery vectors. However, the in vivo use of these PEIs can be hampered by their cellular toxicity. In the present study we developed and tested a new PEI polymer synthesized by linking less toxic, low molecular weight (MW) PEIs with a commonly used, biocompatible drug carrier, beta-cyclodextrin (CyD).

METHODS AND RESULTS

The terminal CyD hydroxyl groups were activated by 1,1'-carbonyldiimidazole. Each activated CyD then linked two branched PEI molecules with MW of 600 Da to form a CyD-containing polymer with MW of 61 kDa, in which CyD served as a part of the backbone. The PEI-CyD polymer developed was soluble in water and biodegradable. In cell viability assays with sensitive neurons, the polymer performed similarly to low-MW PEIs and displayed much lower cellular cytotoxicity compared to PEI 25 kDa. The gene delivery efficiency of the polymer was comparable to, and at higher polymer/DNA ratios even higher than, that offered by PEI 25 kDa in neural cells. Attractively, intrathecal injection of plasmid DNA complexed by the polymer into the rat spinal cord provided levels of gene expression close to that offered by PEI 25 kDa.

CONCLUSIONS

The polymer reported in the current study displayed improved biocompatibility over non-degradable PEI 25 kDa and mediated gene transfection in cultured neurons and in the central nervous system effectively. The new polymer would be worth exploring further as an in vivo delivery system of therapeutic genetic materials for gene therapy of neurological disorders.

Analysis of luteolin in Elsholtzia blanda Benth. by RP-HPLC

The total luteolin content in Elsholtzia blanda Benth. extracts (EBBE) was determined using reversed phase HPLC. C18 was used as the packing material and 0.01 M phosphate buffer (pH 2)-tetrahydrofuran-isopropanol (70:30:5) as the mobile phase with detection wavelength 360 nm. The recovery of the method was 96.4%-101.8%, and the assay was linear at concentrations from 5 to 200 microg/ml (r = 0.9999). The results indicated that the content of luteolin in EBBE extracted under different conditions varied significantly. This method can be used to optimize the extraction procedure and determine the content of luteolin in Elsholtzia blanda Benth. extracts.

Stereoselectivity and interaction between the glucuronidation of S-(-)- and R-(+)-propranolol in rat hepatic microsomes pretreated with different inducers

Phase II glucuronidation metabolism of side-chain propranolol was studied using microsomes from rats treated with the inducers beta-naphthoflavone (BNF) or dexamethasone (Dex). The glucuronide concentrations of propranolol enantiomers were assayed by RP-HPLC. The kinetic constants of glucuronidation, Km, Vmax and Clint were determined. There are significant differences between the R- and S-enantiomeric glucuronide in Km, Vmax and Clint P < 0.05, P < 0.01 and P < 0.05 in control microsome. There are significant differences in Km and Clint (P < 0.01 or P < 0.001) but no significant differences in Vmax (P > 0.05) between R and S-enantiomeric glucuronide in the microsomes induced with Dex and BNF. The formation of S-(-)-propranolol glucuronide was inhibited by R-(+)-propranolol from the rat microsomes pretreated with BNF and Dex. The glucuronidation metabolism of propranolol enantiomers exhibited the stereoselectivity in rat hepatic microsomes induced with BNF or Dex. Multiple UGT1A and 2B may be involved in stereoselective O-glucuronidation of propranolol enantiomers in rat liver microsomes. The glucuronides produced were in favor of the R-enantiomer. There is an interaction between the glucuronidation of R- and S-enantiomer.

Disposition of quercetin and kaempferol in human following an oral administration of Ginkgo biloba extract tablets

Ten adult volunteers with an average age 28 years were given a single oral dose of six tablets of Ginkgo biloba extract. Quercetin and kaempferol in different period of human urine were determined by using RP-HPLC. The results showed the elimination rate constant k and the absorption rate constant ka of quercetin were slightly more than that of kaempferol; and the absorption half-life (t(1/2a)), the elimination half-life (t(1/2)) and t(max) of quercetin were less than that of kaempferol, the differences were, however, not statistically significant. The mean values of ka were 0.61 h(-1) and 0.55 h(-1), t(1/2a) 1.51 h and 1.56 h, k 0.37 h(-1) and 0.30 h(-1), t(1/2) 2.17 h and 2.76 h, T(max) 2.30 h and 2.68 h for quercetin and kaempferol, respectively, which mean absorption and elimination of quercetin and kaempferol are 0.17% and 0.22%, respectively. Quercetin and kaempferol are excreted in the human urine mainly as glucuronides.

Determination of quercetin and kaempferol in human urine after orally administrated tablet of ginkgo biloba extract by HPLC

A sensitive, simple and accurate method was developed for determination of quercetin and kaempferol in human urine by reversed phase high performance liquid chromatography. The urine samples were analyzed on C18 column. Quercetin and kaempferol were analyzed simultaneously with good separation. UV detector was set at 380 nm. There was a linear relationship between chromatographic area of analytes and concentration of analytes over the concentration range 1.638-81.90 and 1.872-93.60 ng/ml for quercetin and kaempferol, respectively. The recovery of the assay was 99.7+/-6.2 and 97.4+/-7.2% for quercetin and kaempferol, respectively. The within-day and between-day coefficients of variation were less than 9.7 and 16.5% (RSD), respectively. The limit of detection was 1.0 ng/ml for quercetin and 1.1 ng/ml for kaempferol. The limit of quantitation was 1.61+/-0.11 ng/ml (n=5) for quercetin and 1.85+/-0.11 ng/ml (n=5) for kaempferol. The method developed has been applied to determine quercetin and kaempferol after orally administrated tablet of Ginkgo biloba extract in human urine.

Concentration dependent stereoselectivity of propafenone N-depropylation metabolism with human hepatic recombinant CYP1A2

Concentration dependency of stereoselective N-depropylation metabolism of propafenone was studied by using transgenic cell line expressing human CYP1A2. Enantiomers of propafenone and N-depropylpropafenone were separated and assayed simultaneously by RP-HPLC with precolumn GITC chiral derivatization. The experimental results showed that CYP1A2 was involved in enantioselective N-depropylation of propafenone and that the metabolic stereoselectivity depends on substrate concentration. For racemic propafenone, stereoselectivity was observed at low substrate concentration and was not seen at high substrate concentration. For individual isomers, S-(+)-propafenone was metabolized faster than its antipode at higher enantiomer concentrations and R-(-)-propafenone was eliminated faster than its antipode at lower enantiomer concentrations. There is interaction between S- and R-propafenone. R-(-)-propafenone inhibited the metabolism of S-(+)-propafenone with IC50 0.225 mmol/L for human CYP1A2.

Milk and milk components reduce the motility ofOstertagia circumcinctalarvaein vitro

AIM

To examine the effects in vitro of bovine milk and milk products and soymilk on the motility of sheathed and exsheathed L3 Ostertagia circumcincta (also known as Teladorsagia circumcincta) as a measure of larval viability and infectivity.

METHODS

L3 were exsheathed in 0.2% sodium hypochlorite, resuspended in Hank's Balanced Salt Solution (HBSS) pH 7.4 and incubated with test solutions at 37 degrees C for up to 48 h. The motility of 50 larvae from each incubate was assessed at selected times using a McMaster slide. Larvae were considered immotile only if straight and not moving. Fresh bovine milk, homogenised milk (3.3% fat), low-fat milk (0.2% fat) and lamb milk replacer were diluted with HBSS pH 7.4 to concentrations from 1.6-100%, and incubated with exsheathed L3 for 1, 24 or 48 h. Bovine whey protein was tested in concentrations of 5-15% at pH 2.5-6.5, casein at 5 or 7.5%, and skim milk powder from 5-15% at pH 5.5 or 6.5, all for 2, 4 or 24 h. Soymilk was tested in concentrations of 1.6-100% for 1, 2, 24 or 48 h. HBSS was used as the control solution. Sheathed L3 were incubated in HBSS pH 7.4, 50% homogenised milk in HBSS, or 50% soymilk in HBSS. Each solution was incubated for 1,2, 24 or 48 h.

RESULTS

The motility of exsheathed L3 was reduced by fresh bovine milk, homogenised milk, low-fat milk, lamb milk replacer, whey, casein and skim milk solutions, but not by soymilk. The mean percentage (and SE) immotile at 48 h were: fresh milk 38% (SE 20); homogenised milk 65% (SE 7); low-fat milk 57% (SE 5); lamb milk replacer 43% (SE 7); and soymilk 7% (SE 0.5). Larval immotility increased in whey protein solutions from 5-15%, from pH 2.5-6.5 and from 2 to 24 h (all p<0.001); in skim milk from 5-15% (p<0.001), and was greater at pH 6.5 than at pH 5.5 (p<0.001); in casein from 5-7.5% (p<0.001), but was no different at pH 5.5 and 6.5. The motility of sheathed L3 was reduced at 24 h (p=0.009) and 48 h (p<0.001) by 50% homogenised milk, but not by 50% soymilk or HBSS.

CONCLUSIONS

Bovine milk proteins, or components associated with the proteins, reduced the motility of both sheathed and exsheathed L3 O. circumcincta. Soymilk had no effect on nematode motility. Lower larval motility may reduce worm establishment and be a contributing factor to the smaller burdens of gastrointestinal nematodes in milk-fed animals compared with animals after weaning.

Determination of dextromethorphan and its metabolite dextrorphan in human urine by capillary gas chromatography without derivatization

A sensitive, simple and accurate method was developed for determination of dextromethorphan (DM) and dextrorphan (DT) in human urine by capillary gas chromatography without derivatization. After an oral dose of 30 mg DM, urine samples were collected and extracted, then analyzed on 0.22 mmx17 m HP-1 capillary column. DM and its metabolite DT were analyzed simultaneously with good separation. Docosane was used as the internal standard (I.S.). The detector used was flame ionization detector (FID). There was a linear relationship between peak area ratios of analytes to I.S. and concentration of analytes over the concentration range 0.37-7.38 micromol/l for DM and 0.39-77.8 micromol/l for DT. The recovery was 88.1 approximately 103.9% for DM and 86.7 approximately 96.8% for DT. The within-day and between-day coefficients of variation were less than 7.4 and 7.3% (RSD) for the assay of DM and DT in urine, respectively. The limits of detection (LOD) were 0.30 micromol/l for DM and 0.16 micromol/l for DT. The limits of quantitation (LOQ) were 0.37 micromol/l (RSD<6%) for DM and 0.39 micromol/l (RSD<7%) for DT. The method has been applied to determine the oxidative phenotypes of cytochrome P450 2D6 (CYP2D6) in a Chinese population with metabolic ratio of DM in human urine.

Chiral reversed phase high-performance liquid chromatography for determining propranolol enantiomers in transgenic Chinese hamster CHL cell lines expressing human cytochrome P450

An enantioselective assay for S-(-)- and R-(+)-propranolol in transgenic Chinese hamster CHL cell lines, expressing human cytochrome P450 (CYP), was developed. The method involves extraction of propranolol from the S(9) incubates, using S-(+)-propafenone as internal standard, chiral derivatization with 2,3,4,6-tetra-O-beta-D-glucopranosyl isothiocyanate and quantitation by reversed phase high-performance liquid chromatography system with UV detection (lambda=220 nm). A baseline separation of propranolol enantiomers was achieved on a 5-microm reverse-phase ODS column, with a mixture of methanol/water/glacial acetic acid (67:33:0.05, v/v) as mobile phase. The assay is linear from 5 to 500 microM for each enantiomer. The analytical method affords average recoveries of 99.2% and 98.8% for S-(-)- and R-(+)-propranolol, respectively. The limit of quantitation for the method is 5 microM for both S-(-)- and R-(+)-propranolol. The reproducibility of the assay is satisfactory (RSD < 10%). The method allowed study of the depletion of S-(-)- and R-(+)-propranolol in transgenic Chinese hamster CHL cell lines expressing CYP3A4, CYP2C18 and CYP2C9.

Chiral metabolism of propafenone in rat hepatic microsomes treated with two inducers

AIM: To study the influence of inducers of drug metabolism enzyme, β-naphthoflavone (BNF) and dexamethasone (DEX), on the stereoselective metabolism of propafenone in the rat hepatic microsomes.

METHODS: Phase I metabolism of propafenone was studied using the microsomes induced by BNF and DEX and the non-induced microsome was used as the control. The enzymatic kinetics parameters of propafenone enantiomers were calculated by regress analysis of Eadie-Hofstee Plots. Propafenone enantiomer concentrations were assayed by a chiral HPLC.

RESULTS: The metabolite of propafenone, N-desalkylpropafenone, was found after incubation of propafenone with the rat hepatic microsomes induced by BNF and DEX. In these two groups, the stereoselectivity favoring R (-) isomer was observed in metabolism at low substrate concentrations of racemic propafenone, but lost the stereoselectivity at high substrate concentrations. However, in control group, no stereoselectivity was observed. The enzyme kinetic parameters were: ① K_m. Control group: R (-) 83 ± 6, S (+) 94 ± 7; BNF group: R (-) 105 ± 6, S (+) 128 ± 14; DEX group: R (-) 86 ± 11, S (+) 118 ± 16; ② υ_max. Control group: R (-) 0.75 ± 0.16, S (+) 0.72 ± 0.07; BNF group: R (-)1.04 ± 0.15, S (+)1.0 7 ± 14; DEX group: R (-) 0.93 ± 0.06, S (+) 1.04 ± 0.09; ③ Cl_int. Control group: R (-) 8.9 ± 1.1, S (+) 7.6 ± 0.7; BNF group: R (-)9.9 ± 0.9, S (+)8.3 ± 0.7; DEX group: R (-) 10.9 ± 0.8, S (+) 8.9 ± 0.9. The enantiomeric differences in K_m and Cl_int were both significant, but not in υ_max, in BNF and DEX group. Whereas enantiomeric differences in three parameters were all insignificant in control group. Furthermore, K_m and υ max were both significantly less than those in BNF or DEX group. In the rat liver microsome in duced by DEX, nimodipine (NDP) decreased the stereoselectivity in propafenone metabolism at low substrate concentration. The inhibition of NDP on the metabolism of propafenone was stereo selective with R (-)-isomer being impaired more than S (+)-isomer. The inhibition constant (Ki) of S (+)- and R (-)-propafenone, calculated from Dixon plots, was 15.4 and 8.6 mg•L¯¹, respectively.

CONCLUSION: CYP1A subfamily (induced by BNF) and CYP3A4 (induced by DEX) have pronounced contribution to propafenone N-desalkylation which exhibited stereose lectivity depending on substrate concentration. The molecular base for this phenomenon is the stereo selectivity in affinity of substrate to the enzyme activity centers instead of at the catalyzing sites.

Immobilisation on polystyrene of diazirine derivatives of mono- and disaccharides: biological activities of modified surfaces

The potential of surface glycoengineering for biomaterials and biosensors originates from the importance of carbohydrate-protein interactions in biological systems. The strategy employed here utilises carbene generated by illumination of diazirine to achieve covalent bonding of carbohydrates. Here, we describe the synthesis of an aryl diazirine containing a disaccharide (lactose). Surface analysis techniques [X-ray photoelectron spectroscopy (XPS) and time of flight secondary ion mass spectroscopy (ToF-SIMS)] demonstrate its successful surface immobilisation on polystyrene (PS). Results are compared to those previously obtained with an aryl diazirine containing a monosaccharide (galactose). The biological activity of galactose- or lactose-modified PS samples is studied using rat hepatocytes, Allo A lectin and solid-phase semi-synthesis with alpha-2,6-sialyltransferase. Allo A shows some binding to galactose-modified PS but none to lactose-modified surfaces. Similar results are obtained with rat hepatocytes. In contrast, sialylation of lactose-modified PS is achieved but not with galactose-modified surfaces. The different responses indicate that the biological activity depends not only on the carbohydrate per se but also on the structure and length of the spacer.

[Muscarinic receptor subtype-3 expression in trabecular meshwork of normal human eye and primary open-angle glaucoma]

OBJECTIVE

To identify the muscarinic receptor subtype-3 (M3-receptor) expression in trabecular meshworks (TM) of normal human eyes and eyes with primary open-angle glaucoma (POAG) and discuss the pathological changes of TM in POAG.

METHOD

TM specimens were taken from 5 normal persons and 10 patients with POAG at late stage. Then LSAB immunohistochemical technique was used to identify M3-receptors. The results were observed under microscope and compared with computer-image-analysis system.

RESULTS

(1) The trabecular meshwork cells in all the 5 normal persons expressed M3-receptors. The positive cells mainly existed in the uveal part of TM, from Schwalbe's line to scleral spur. (2) In TM from eyes with POAG, the amount of both TM cells and M3-receptor positive cells were reduced obviously, even some specimens had no such positive expression. The positive cells were correspondingly decreased in number and scattered in distribution.

CONCLUSION

The TM cells in normal human eyes express M3-receptors. The TM cells and M3-positive cells in eyes with late POAG are reduced in number and their distribution is irregular.

Stereoselective metabolism of propafenone by human liver CYP3A4 expressed in transgenic Chinese hamster CHL cells lines

AIM

To investigate the stereoselective metabolism of propafenone (PPF) by human liver CYP3A4.

METHODS

A chiral and an achiral HPLC were combined to determine the enantiomer of PPF in S9 incubates prepared from transgenic Chinese hamster CHL cells lines expressing CYP3A4. The time-dependent study was performed using individual enantiomer or racemate at low or high substrate concentration. Kinetic parameters were determined employing individual enantiomers as substrates. Enantiomeric inhibition experiments were performed by using R(-)-PPF as an inhibitor and S(+)-PPF as a substrate.

RESULTS

Stereoselectivity was found in metabolism of racemic PPF at low substrate concentration (10 mg/L) (S < R), and lost at high substrate concentration (400 mg/L) When an individual enantiomer of high concentration (200 mg/L) was used as a substrate, S(+)-PPF was eliminated faster than its isomer (S < R). However, the opposite situation was observed at low concentration (5 mg/L) (S < R). The Vmax of S(+)-PPF was significantly greater than that of R(-)-PPF [(2.66 +/- 0.32) vs (1.71 +/- 0.19) micromol . mg-1 . min-1]. The Km of R(-)-PPF was significantly lower than that of S(+)-PPF [(73 +/- 11) vs (185 +/- 17) micromol/L]. R(-)-PPF inhibited S(+)-isomer with an IC50 value of 125 micromol . L-1.

CONCLUSION

It is concluded that stereoselectivity in metabolism of propafenone via CYP3A4 depend on substrate concentration. Enantiomer/enantiomer interaction of PPF occurred at high concentration of substrate, and resulted in the loss of stereoselectivity. There maybe no enantiomer/enantiomer interaction at low concentration thus keeping the superiority of R(-)-PPF in metabolism.

Highly toxic and broad-spectrum insecticidal Bacillus thuringiensis engineered by using the transposon Tn917 and protoplast fusion

The chromosome of the Bacillus thuringiensis strain S184 that was toxic against the third instar larvae of Spodoptera litura with the LC(50) of 9.74 microg/ml was successfully integrated into two genes of cyt1Aa and cry11Aa using the transposon Tn917, yielding the primary engineered strain TnX. The strain TnX was highly toxic to the third instar larvae of Culex pipiens fatigans with the LC(50) of 5.12 ng/ml which was 1.82-fold higher than that of B. thuringiensis subsp. israelensis, but lowly toxic to lepidopterous larvae. By the protoplast fusion of the strain TnX and the strain S184-Tet(r) (resistance to tetracycline), the target engineered strain TnY was obtained. Against the third instar larvae of S. litura, the strain TnY LC(50) was of 4.68 micro g/ml and increased by 2.08-fold in comparison with the parent strain S184. Against the third instar larvae of C. pipiens fatigans, the strain TnY LC(50) was of 103.20 ng/ml. The two target genes of cyt1Aa and cry11Aa integrated into the chromosome were extremely stable and had little possibility of a second transposition. It was unclear whether some factors existing in the parent strain, S184, contributed to the high toxicity of the strains TnX and TnY.

Stereoselective determination of p-hydroxyphenyl-phenylhydantoin enantiomers in rat liver microsomal incubates by reversed-phase high-performance liquid chromatography using beta-cyclodextrin as chiral mobile phase additives

An analytical method was developed for determination of p-hydroxyphenylphenylhydantoin enantiomers in rat liver microsome by using reversed-phase high-performance liquid chromatography. A 50 mm C(8) column was used as the analytical column. The mobile phase was made up of 8.8 mmol/L beta-cyclodextrin, 0.25 mol/L urea and 0.05 mol/L ammonium acetate in water. The assay was linear from 2.05 to 410.0 micromol/L for each enantiomer. The limits of detection and of quantitation for the method were 0.90 and 2.05 micromol/L for each enantiomer, respectively. The analytical method afforded average recoveries of 93.59 +/- 2.75% and 94.72 +/- 1.78% for S- and R-p-hydroxyphenylphenylhydantoin, respectively. The method allowed study of the in vitro glucuronidation of p-hydroxyphenylphenylhydantoin in rat liver microsomal incubates. The stereoselectivity of p-hydroxyphenylphenylhydantoin phase II metabolism was observed.

[Study on anticancer activity of Syngnathus in vitro]

OBJECTIVE

To study the anticancer activity of Syngnathus in vitro.

METHOD

Observing the influence of different extracts from Syngnathus on growth of different cancer cell strains by MTT method.

RESULT

It has been found out that the fat-soluble nonsaponified extract from Temminck et Schlegel and the alcoholic extract from Syngnathus acus have cytotoxic activities. The nonsaponified extract from Temminck et Schlegel can inhibit the growth of cancer cell strains KB, Hela, PAA, K562, and Bcap37, and the alcoholic extract from Syngnathus acus can inhibit the growth of cancer cell strin KB, But Bloch shows no apparent anticancer activity.

CONCLUSION

Syngnathus has promising prospects as an anticancer Chinese medicine.

Phenotype analysis of cytochrome P450 2C19 in Chinese subjects with mephenytoin S/R enantiomeric ratio in urine measured by chiral GC

A chiral gas chromatographic method with FID was developed for the determination of S- and R-mephenytoin in human urine. The assay is linear from 25 to 800 ng/mL for each enantiomer and the limit of detection and limit of quantitation were 12 and 25ng/mL for each enantiomer, respectively. The method affords average recoveries of 74.41 +/- 3.93% and 73.78 +/- 3.02% for S- and R-mephenytoin, respectively. The method allows the phenotype study of CYP2C19 in Chinese subjects. The phenotype pattern of 90 Chinese volunteers was determined, in which 26 volunteers received phenotyping and genotyping tests. The results of phenotype analysis showed that the interindividual variation was marked. The mephenytoin S/R enantiomeric ratios in urine of 11 volunteers were > or = 0.95 and identified as poor metabolizers. The frequency of poor metabolizers was 12.2% in the Chinese subjects tested. A good relationship between phenotype and genotype analysis of CYP2C19 was observed.

Stereoselective determination of propafenone enantiomers in transgenic Chinese hamster CHL cells expressing human cytochrome P450

An enantioselective assay for S(+)- and R(-)-propafenone in transgenic Chinese hamster CHL cells expressing human cytochrome P450 was developed. The method involved extraction of propafenone from the S9s incubates, and formation of propafenone diastereomeric derivatives with the chiral reagent 2,3,4, 6-tetra-O-beta-D-glucopranosyl isothiocyanate. Separation and quantitation of diastereomeric propafenone derivatives were carried out in a reverse-phase-HPLC system with UV detection. The assay was linear from 2 to 200 microg/mL for each enantiomer. The analytical method gave average recoveries of 97.5% and 97.0% for S(+)- and R(-)-propafenone, respectively. The limits of detection and quantitation for the method are 0.1 and 2.0 microg/mL for both S(+)- and R(-)-propafenone, respectively. The reproducibility of the assay was good (RSD <10%). The method allowed study of the depletion of S(+)- and R(-)-propafenone in transgenic Chinese hamster CHL cells expressing human cytochrome P450. The stereoselectivity of propafenone phase I metabolism via cDNA-expressed CYP3A4 was observed.

The anti-proliferative effect of inhibitor of telomerase on cultured retinal pigment epithelial cells

In order to provide a new method for treating proliferative vitreoretinopathy (PVR), the effects of anti-proliferation and apoptosis induction of inhibitors of telomerase and heat shock protein 90 (Hsp90) on the cultured retinal pigment epithelial (RPE) cells were investigated. The rate of apoptosis cells was measured by using TUNEL on the cultured RPE cells, the co-cultured RPE cells with inhibitor of telomerase (camptothecin) or the co-cultured RPE cells with inhibitor of Hsp90 (geldanamycin). The cell proliferation status was measured in the above three groups by using MTT method. The rate of apoptosis in the RPE cells co-cultured with camptothecin or geldanamycin was increased remarkably (P < 0.05). MTT showed the rate of growth inhibition was 8.4%, 32.3% and 72.3% at the concentrations of camptothecin 1 mumol/L, 5 mumol/L, 10 mumol/L, respectively, and 6.5%, 30.9%, 71.9% at the concentrations of geldanamycin 1 mumol/L, 5 mumol/L, 10 mumol/L, respectively. It was concluded that telomerase and Hsp90 can promote the proliferation of the cultured RPE cells, while the inhibitor of them can induce apoptosis and inhibit the growth of the RPE cells.

[The muscarinic receptor subtype study of the action on lowering IOP of cholinomimetic drugs]

PURPOSE

Clarify the relationship between lowering intraocular pressure (IOP) action of cholinomimetic drugs and muscarinic receptor subtypes.

METHODS

Measuring rabbit IOP with gas driving ophthalmotonometer, measuring size of pupil with pupil rule and measuring contraction of rabbit iris by iris experiment in vitro. Figuring out pD2 of cholinomimetic drugs and pA2 of the antagonists of muscarinic receptor subtypes.

RESULTS

The order of effect on lowering IOP and miosis of cholinomimetic drugs is Erycibele Alkaloid > Aceclidine > Pilocarpine and the order of effect on constracting iris is Erycibele Alkaloid > Pilocarpine > Aceclidine. The sequence of antagonistic effect of subtype antagonists is 4-DAMP(M3) > Pirenzepine(M1) > Gallamine(M2).

CONCLUSION

Effect cholinomimetics on lowing IOP and miosis is primary mediated by M3 receptor, next by M1 receptor and has little relation with M2 receptor.

Stereoselective determination of propafenone enantiomers in transgenic Chinese hamster CHL cells expressing human cytochrome P450

An enantioselective assay for S(+)- and R(-)-propafenone in transgenic Chinese hamster CHL cells expressing human cytochrome P450 was developed. The method involved extraction of propafenone from the S9s incubates, and formation of propafenone diastereomeric derivatives with the chiral reagent 2,3,4, 6-tetra-O-beta-D-glucopranosyl isothiocyanate. Separation and quantitation of diastereomeric propafenone derivatives were carried out in a reverse-phase-HPLC system with UV detection. The assay was linear from 2 to 200 microg/mL for each enantiomer. The analytical method gave average recoveries of 97.5% and 97.0% for S(+)- and R(-)-propafenone, respectively. The limits of detection and quantitation for the method are 0.1 and 2.0 microg/mL for both S(+)- and R(-)-propafenone, respectively. The reproducibility of the assay was good (RSD <10%). The method allowed study of the depletion of S(+)- and R(-)-propafenone in transgenic Chinese hamster CHL cells expressing human cytochrome P450. The stereoselectivity of propafenone phase I metabolism via cDNA-expressed CYP3A4 was observed.

Stable and unstable transgene integration sites in the human genome: extinction of the Green Fluorescent Protein transgene in K562 cells

In gene transfer experiments including gene therapy studies, expression of the integrated transgenes in host cells often declines with time. The molecular basis of this phenomenon is not clearly understood. We have used the Green Fluorescent Protein (GFP) gene as both a selectable marker and a reporter to study long-term transgene integration and expression in K562 cells. Cells transfected with plasmids containing the GFP gene coupled to the HS2 or HS3 enhancer of the human beta-globin Locus Control Region (LCR) or the cytomegalovirus (CMV) enhancer were sorted by either fluorescence-activated-cell-sorting (FACS) alone or FACS combined with drug selection based on a co-integrated drug resistance gene. The two groups of selected cells were subsequently cultured for long periods up to 250 cell generations. Comparison of long-term GFP transgene integration and expression in these two groups of cells revealed that the K562 genome contains two types of transgene integration sites: i) abundant unstable sites that permit transcription but not long-term integration of the transgenes and thus eliminate the transgenes in 60-250 cell generations and ii) rare stable sites that permit both efficient transcription and long-term stable integration of the transgenes for at least 200 cell generations. Our results indicate that extinction of GFP expression with time is due at least in part to elimination of the gene from the host genome and not entirely to transcriptional silencing of the gene. However, long-term, stable expression of the transgene can be achieved in cells containing the transgene integrated into the rare, stable host sites.

Inhibition of the amygdala and hippocampal calcium/calmodulin-dependent protein kinase II attenuates the dependence and relapse to morphine differently in rats

Learning and memory have been suggested to play an important role in the development of opiate addiction. Based on the recent finding that calcium/calmodulin protein kinase II (CaMKII) is essential in learning and memory processes, the present study was performed to examine whether inhibition of hippocampal and amygdala CaMKII prevents the dependence and relapse to morphine. The results showed that inhibition of CaMKII by microinjection of specific inhibitors KN-62 into hippocampus decreased the morphine withdrawal syndromes induced by opiate antagonist naloxone. In contrast, inhibition of CaMKII in amygdala failed to do so. Microinjection of KN-62 into both hippocampus and amygdala suppressed the development of formation and reactivation of morphine conditioned place preference (CPP). However, inhibition of CaMKII in amygdala, but not in hippocampus, could attenuate the maintenance of morphine CPP. These results suggest that hippocampal CaMKII is critically involved in the development of morphine physical and psychological dependence, and amygdala CaMKII is some different from hippocampal CaMKII in regulating the dependence and relapse to opiates. Inhibition of this kinase may have some therapeutic benefit in the treatment of opiate dependence and relapse.

In vitro evaluation of schedule-dependent interactions between docetaxel and doxorubicin against human breast and ovarian cancer cells

Docetaxel, a novel member of the taxoid family, has shown greater potency than paclitaxel in the treatment of advanced breast cancer and certain other solid tumors. The promising clinical activity of docetaxel has also promoted considerable interest in combining this drug with other antitumor agents. In this study, we assessed the cytotoxic interaction between docetaxel and doxorubicin administered at various schedules to human breast and ovarian cancer cells. Through a series of in vitro assays including DNA fragmentation analyses, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays, and flow cytometric analyses, we found that the antagonistic interaction occurred when tumor cells were exposed to the two drugs simultaneously or exposed to doxorubicin before docetaxel. However, no antagonism was observed when docetaxel was added before doxorubicin. Further analyses demonstrated that doxorubicin could interfere with the cytotoxic effect of docetaxel on both mitotic arrest and apoptotic cell death. In addition, biochemical examinations revealed that docetaxel could induce phosphorylation of both bcl-2 and c-raf-1, but these changes were inhibited when tumor cells were pretreated or simultaneously treated with doxorubicin. These results indicate that the interaction between docetaxel and doxorubicin is highly schedule dependent. Exposure of tumor cells to doxorubicin before docetaxel could result in pronounced antagonism. The optimal schedule for this combination might be sequential exposure to docetaxel followed by doxorubicin.

Reversed-phase high-performance liquid chromatographic analysis of atenolol enantiomers in rat hepatic microsome after chiral derivatizaton with 2,3,4,6,-tetra-O-acetyl-beta-D-glycopyranosyl isothiocyanate

A reversed-phase high-performance liquid chromatographic method for the determination of the enantiomers of atenolol in rat hepatic microsome has been developed. Racemic atenolol was extracted from alkalinized rat hepatic microsome by ethyl acetate. The organic layer was dried with anhydrous sodium sulfate and evaporated using a gentle stream of air. Atenolol racemic compound was derivatized with 2,3,4,6-tetra-O-acetyl-beta-D-glycopyranosyl isothiocyanate at 35 degrees C for 30 min to form diastereomers. After removal of excess solvent, the diastereomers were dissolved in phosphate buffer (pH 4.6)-acetonitrile (50:30). The diastereomers were separated on a Shimadzu CLC-C18 column (10 microm particle size, 10 cm x 0.46 cm I.D.) with a mobile phase of phosphate buffer-methanol-acetonitrile (50:20:30, v/v) at a flow-rate of 0.5 ml/min. A UV-VIS detector was operated at 254 nm. For each enantiomer, the limit of detection was 0.055 microg/ml (signal-to-noise ratio 3) and the limit of quantification (signal-to-noise ratio 10) was 0.145 microg/ml (RSD <10%). In the range 0.145-20 microg/ml, intra-day coefficients of variation were 1.0-7.0% and inter-day coefficients of variation were 0.4-16.5% for each enantiomer. The assay was applied to determine the concentrations of atenolol enantiomers in rat hepatic microsome as a function of time after incubation of racemic atenolol.

[Inhibitory effects of ligustrazine on the expression of intercellular cell adhesion molecule-1, vascular cell adhesion molecule-1 in human umbilical vein endothelial cells induced by preeclamptic plasma]

OBJECTIVE

To determine whether plasma from preeclamptic women induces expression of intercellular cell adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) on cultured endothelial cells, and the effects of ligustrazine (LTZ) on the expression of ICAM-1, VCAM-1.

METHODS

Human umbilical vein endothelial cells (HUVEC) were isolated by collagenase mixed with trypsin. LTZ was added to HUVEC monolayers grown to confluency on 96-well microplates for 30 minutes. Then HUVEC were incubated with medium containing 20% plasma (volume/volume) either from women with preeclampsia or normotensive pregnancy or nonpregnant women. ICAM-1, VCAM-1 expression was determined after 16 hours of exposure by an enzyme-linked immunosorbent assay (ELISA) technique performed on the cell monolayer.

RESULTS

There was a statistically significant increase in ICAM-1, VCAM-1 expression in the endothelial cells exposed to preeclamptic and nonpregnant plasma compared with those exposed to normotensive plasma. Pretreatment with LTZ could reduce the expression of ICAM-1 exposed to preeclamptic plasma, and reduce the expression of VCAM-1 exposed to any of the three sources of plasma.

CONCLUSIONS

Preeclamptic plasma induces ICAM-1 and VCAM-1 expression in HUVEC in vitro. Ligustrazine may inhibit the upregulation effects of ICAM-1 and VCAM-1 expression induced by preeclamptic plasma.

[Study on smoking pattern and related factors among residents aged over 15 years in Guangdong province]

OBJECTIVE

To investigate the prevalence of smoking and related factors among residents aged over 15 years in Guangdong province.

METHODS

Sampling survey, descriptive analysis and nonconditional logistic regression.

RESULTS

Rates on general smoking, current smoking, regular smoking and heavy smoking among male residents aged over 15 years were 70.03%, 66.57%, 65.16% and 35.47% respectively and those among females were 3.04%, 2.67%, 2.54% and 1.12% respectively. There was significant difference between sex distribution. 86.71% of the male smokers started smoking at 15 to 29 years old, while the age distribution of noset of smoking among females was more scattered. Main reasons of starting smoking were to experience with social pressure and getting rid of feelings of fatigue. Tobacco products they often smoked included filter tip cigarette, handmade cigarette or dry cigarette. 52.42% of the smokers claimed that they often smoked in public places. 66.7% of the residents believed that smoking was either no harm or just minor while, 35.5% of them believed that smoking could get rid of fatigue and enhance the efficiency of work. Sex, age, occupation, marriage status and knowledge about the harm of smoking to health were factors related to smoking.

CONCLUSION

Smoking has laid great harm to the health of residents in Guangdong province. Health education, stopping smoking in public places and no advertisement of cigarette under the management of laws are the best way to control the harm of smoking.

A new video-synchronized multichannel biomedical data acquisition system

This data acquisition system records video frames onto a video tape, and simultaneously acquires biomedical data along with video time codes onto a computer hard disk to achieve a 30-min video-synchronized data recording with a summed data rate of 2.16 Mbit/s. A time-code-bridge-file created during acquisition matches each video frame-start with the corresponding index number of the acquired data. The mean synchronization accuracy of the system is 0.22 ms.

[Tissue culture and rapid propagation of Aloe arborescens]

Tissue culture and rapid propagation of Aloe arborescens have been studied. The main results are as follows: the optimum medium for cluster shoots induction is MS + 6-BA 3.0 mg/L + NAA 0.2 mg/L; for cluster shoots propagation is MS + 6-BA 2.0 mg/L + NAA 0.2 mg/L; for roots induction is 1/2 MS + NAA 0.5 mg/L. The survival rate of the tube plantlets is 100% in the transplanting. Cutting down the cost of medium in large scale of production have been studied also.

Expression of functional soluble forms of human beta-1, 4-galactosyltransferase I, alpha-2,6-sialyltransferase, and alpha-1, 3-fucosyltransferase VI in the methylotrophic yeast Pichia pastoris

The cDNAs encoding soluble forms of human beta-1, 4-galactosyltransferase I (EC 2.4.1.22), alpha-2,6-sialyltransferase (EC 2.4.99.1), and alpha-1,3-fucosyltransferase VI (EC 2.4.1.65), respectively, have been expressed in the methylotrophic yeast Pichia pastoris. The vector pPIC9 was used, which contains the N-terminal signal sequence of Saccharomyces cerevisiae alpha-factor to allow entry into the secretory pathway. The recombinant enzymes had similar kinetic properties as their native counterparts. Their identity was confirmed by Western blotting. Recombinant enzymes may be used for in vitro synthesis of oligosaccharides.

[The effect of erycibele alkaloid on intracellular Ca2+ mobilation of cultured human ciliary muscle cells]

PURPOSE

To study the effect of erycibele alkaloid on cultured human ciliary muscle intracellular Ca2+ movement.

METHODS

Intracellular Ca2+ was studied by Fura-2 probe and muscarinic antangonist was applied.

RESULTS

Erycibele alkaloid had no any possible disturbulance on the examination system. The average resting[Ca2+]i was 79.3 +/- 28.7 nmol/Lol/L (n = 24). Erycibele alkaloid caused biphase [Ca2+]i elevation. Non-selective muscarinic antagonist Atropine (1 nmol/L) could completely block the 1 mumol/L erycibele alkaloid induced [Ca2+]i elevation; M1 antagonist Pirenzipine could not block the 1 mumol/L erycibele alkaloid induced [Ca2+]i elevation in low concentration (0.03 nmol/L) but in higher concentration (1 nmol/L). M3 antagonist 4-diphenyl acetoxy N-methy piperidine methiodide could completely block the 1 mumol/L erycibele alkaloid induced [Ca2+]i elevation in low and high concentration.

CONCLUSION

The effect of erycibele alkaloid on increasing cultured human ciliary muscle cell intracellular Ca2+ is mediated by M3 receptor subtype.

Migration of Polystyrene Latex Particle Bands in Density-Gradient Electrophoresis

Electrophoretic migration of sulfated polystyrene latex particle bands was investigated in a density-gradient electrophoresis apparatus. The bands spread with time, and their velocity was found to depend on particle concentration and to decrease during the initial stages of electrophoresis. A change in pH during electrophoresis occurred, and this change may have caused variations in band velocity. Copyright 1999 Academic Press.

Platelet activating factor-induced P-selectin expression in platelets and its related signal transduction

AIM

To study the intracellular signal transduction mechanisms of platelet activating factor (PAF)-induced platelet P-selectin expression.

METHODS

Human blood platelets were used to test the effect of PAF-induced P-selectin expression using flow cytometry.

RESULTS

PAF 20 nmol.L-1 elicited a moderate upregulation of P-selectin expression [(47.5 +/- 1.3)% vs control (3.8 +/- 0.9)%, P < 0.01]. Pretreatment with egtazic acid (EGTA) 2 mmol.L-1 and 5,5'- dimethyl-bis-(o-aminophenoxy)-ethane-N,N,N',N'-tetracetic acid (BAPTA) 200 mumol.L-1 to block Ca2+ influx or chelate the intracellular calcium, respectively, reduced P-selectin expression in response to PAF [(13.3 +/- 0.9)% and (16.8 +/- 1.9)% vs (47.5 +/- 1.3)% of PAF group, P < 0.01]. Inhibition of Na+/H+ exchange with amiloride (Ami) 400 mumol.L-1 resulted in an inhibition of P-selectin expression [(37.5 +/- 2.1)% vs (47.5 +/- 1.3)% of PAF group, P < 0.01]. Genistein (Gen) 300 mumol.L-1 to inhibit protein tyrosine phosphorylation showed similar effect [(29 +/- 4)% vs (47.5 +/- 1.3)% of PAF group, P < 0.01].

CONCLUSION

Multiple signal transduction pathways, including protein tyrosine phosphorylation, Na+/H+ exchange, and Ca2+ mobilization, mediated PAF-induced P-selectin expression.

Complete enzymic synthesis of the mucin-type sialyl Lewis x epitope, involved in the interaction between PSGL-1 and P-selectin

Sialyl Lewis x (sLe(x)) is an established selectin ligand occurring on N- and O-linked glycans. Using a completely enzymic approach starting from p-nitrophenyl N-acetyl-alpha-D-galactosaminide (GalNAc(alpha1-pNp as core substrate, the sLe(x)-oligosaccharide Neu5Ac(alpha2-3)Gal(beta1-4)[Fuc(alpha1-3)]GlcNAc(beta1-6)[Gal(bet a1-3)]GalNAc(alpha1-pNp, representing the O-linked form, was synthesized in an overall yield of 32%. In a first step, Gal(beta1-3)GalNAc(alpha1-pNp was prepared in a yield of 52% using UDP-Gal and an enriched preparation of beta3-galactosyltransferase (EC 2.4.1.122) from rat liver. UDP-GlcNAc and a recombinant affinity-purified preparation of core 2 beta6-N-acetylglucosaminyltransferase (EC 2.4.1.102) fused to Protein A were used to branch the core 1 structure, affording GlcNAc(beta1-6)[Gal(beta1-3)]GalNAc(alpha1-pNp in a yield of >85%. The core 2 structure was galactosylated using UDP-Gal and purified human milk beta4-galactosyltransferase 1 (EC 2.4.1.38) (yield of >85%), then sialylated using CMP-Neu5Ac and purified recombinant alpha3-sialyltransferase 3 (EC 2.4.99.X) (yield of 87%), and finally fucosylated using GDP-Fuc and recombinant human alpha3-fucosyltransferase 6 (EC 2.4.1.152) produced in Pichia pastoris (yield of 100%). Overall 1.5 micromol of product was prepared. MALDI TOF mass spectra, and 1D and 2D TOCSY and ROESY 1H NMR analysis confirmed the obtained structure.

[Influence of intravenous-immunoglobulin on T lymphocyte subsets, NK cell and some cytokines in mice with experimental viral myocarditis]

This study sought to gain an insight into the immunological pathogenesis of viral myocarditis and the mechanism of therapeutic action of intravenous-immunoglobulin (IVIG) on the disease, BALB/c mice were randomized into four groups: normal control group; "myocarditis model group", inoculated intraperitoneally with CVB3; "IVIG protection group", injected intraperitoneally with CVB3 and IVIG; and "IVIG treatment groups", injected intraperitoneally with CVB3 and IVIG. The amount of T cell in different T cell subsets and the activities of NK cell, IL-1 and IL-2 were assayed using spleen specimen while peripheral blood was used to measure TNF activity. The results showed: that in comparison with normal control, all spleen T cell subsets decreased in amount in myocarditis model group, so did its NK cell activity while its IL-1, IL-2 and TNF activities increased significantly. When compared with myocarditis model group, however, both IVIG protection group and IVIG treatment group showed significant elevation of NK cell activity and T cell subsets but reduced IL-1, IL-2 and TNF activities with no remarkable change in T cell subsets. The results of suggest that the immunological injury mediated by T cells plays a critical role in the pathogenesis of viral myocarditis. The protective and therapeutic effects of IVIG on the murine CVB3 myocarditis and the related immunological evidence of its actions may indicate the prospect that IVIG will become a potent and safe treatment for viral myocarditis in human.

Hydrolysis of extracellular adenine nucleotides by cultured bovine endocardial endothelial cells

AIM

To characterize the ATP diphosphohydrolase (apyrase) of bovine endocardial endothelial cells, and to compare ecto-adeninenucleotidase activity between bovine endocardial and aortic endothelial cells (BEEC and BAEC).

METHODS

The nucleotide was analyzed by reversed phase HPLC and apyrase activity was assayed by inorganic phosphate release.

RESULTS

Apyrase inhibitors, both NaN3 10 mmol.L-1 and NaF 20 mmol.L-1, inhibited BEEC apyrase activity by 51% and 38%, respectively. The inhibitor for Na+/K(+)-ATPase, ouabain, did not affect the enzyme activity. Edetic acid 5 mmol.L-1 completely inhibited the enzyme activity. H2O2 0.5 mmol.L-1 downregulated BEEC apyrase activity in a time-dependent manner. The apyrases activities in BAEC were higher than those in BEEC, while the ecto-AMPase activity in BAEC was much weaker than that in BEEC.

CONCLUSION

BEEC have NaN3- and NaF-sensitive, ouabain-insensitive apyrase activity. BEEC had high ecto-AMPase activities, and low apyrases activities as compared with BAEC.

Heterogeneity of HLA-DR2 haplotypes in Caucasoid Americans, African Americans, Chinese Americans, Native Americans and Xiamen Chinese

HLA-DR, -DQ specificities were determined by PCR amplification with SSOP in 4560 individuals: Caucasoid Americans (CA), African Americans (AA), Chinese Americans (ChA), Native Americans (NA) and Xiamen Chinese (XC). DR2 subtypes were compared amongst the five ethnic populations. The DRB1*1501-DRB5*0101 haplotype was found to be the most frequent in all populations except African Americans, in which DRB1*1503-DRB5*0101 was the predominant haplotype, accounting for 65% of DR2 subtypes. In contrast to Caucasoid Americans, the DRB1*1602 is strongly associated with the DRB5*0101 allele in Chinese populations. The presence of DRB5*0203 and DRB1*1602-DRB5*0101 haplotypes in Chinese populations, especially in Xiamen Chinese, suggests that various DR2 haplotypes may be generated via multiple gene conversion events together with point mutations and reciprocal recombination. The strong DR and DQ associations are found in DRB1*1501/DQB1*0602 (66.22%) for CA, DRB1*1503/DQB1*0602 (56.58%) for AA, DRB1*1501/DQB1*0602 (30.20%) and DRB1*1602/DQB1*0502 (15.76%) for ChA, DRB1* 1501/DQB1*0602 (41.55%) and DRB1*1602/DQB1*0301 (40.25%) for NA, and DRB1*1501/DQB1*0602 (30.26%) and DRB1*1602/DQB1*0502 (25.81%) for XC.

Chiral gas chromatographic assay with flame ionization detection for amphetamine enantiomers in microsomal incubates

A chiral assay for amphetamine enantiomers in rat liver microsomal incubates is based on derivatization with (S)-(-)-N-(trifluoroacetyl)-prolyl chloride (S-TFPC), capillary chromatographic separation of the diastereomeric amide derivatives, and detection by a flame ionization detector. The method is capable of detecting low levels of S- or R-amphetamine. The assay is linear from 5 to 250 micrograms/mL for each enantiomer, and the limit of detection is 0.5 microgram/mL. The analytical method affords the average recoveries of 77.53 +/- 5.22% for R-amphetamine and 74.47 +/- 3.08% for S-amphetamine. The method allows the study of the metabolic depletion of S- and R-amphetamine in rat liver microsomal incubates. The time-dependent concentration of amphetamine enantiomers in rat liver microsomes was determined, and the stereoselectivity of amphetamine phase I metabolism was observed.

High-performance liquid chromatography separation and quantitation of ofloxacin enantiomers in rat microsomes

A sensitive, simple and accurate method for determination of enantiomers of ofloxacin in microsomal incubates was developed by chiral ligand-exchange RP-HPLC with fluorescence detection to examine stereoselective metabolism of ofloxacin in the glucuronidation process. The C18 stationary phase was used as analytical column. The solution of chiral mobile phase additive was made up of 6 mM L-phenylalamine mixed with 3 mM CuSO4 in water. Mobile phase consisted of the solution of chiral mobile phase additive-methanol (86:14). The fluorescence detector was operated at lambda(ex) 330 nm and lambda(em) 505 nm. The flow-rate of mobile phase was set at 1.0 ml/min. The achiral ODS column offers good separation of the two enantiomers in less than 25 min. The recovery of the assay was 97.9+/-6.1% (n=10) for S-ofloxacin and 99.6+/-6.0% (n = 10) for R-ofloxacin. The method provides a high sensitivity and good precision (RSD<10%). The LOD was 0.6 microM for both enantiomers and the LOQ was 5.70+/-0.45 microM (n=8) for S-ofloxacin and 5.66+/-0.47 microM (n=8) for R-ofloxacin. The standard curves showed excellent linearity over the concentration range 5.5-2078 microM for S-(-)-ofloxacin and R-(+)-ofloxacin. The enantioselective method developed has been applied to determine the stereoselectivity of glucuronidation metabolism of ofloxacin optical isomers in rat liver microsomes.

[Studies of the mechanism of lowering intraocular pressure on Erycibele alkaloid]

OBJECTIVE

To investigate the molecular pharmacological mechanism of lowering intraocular pressure of Erycibele alkaloid.

METHODS

Rabbit pupil diameter was measured by a pupillary ruler in constant illumination and the intraocular pressure (IOP) was measured by pneumatonometer. Iris contracting force was measured in an experiment of isolated rabbit iris. Radioimmune method was used to determine the content of cyclonucleotide.

RESULTS

The pD(2) value (the affinity to M-receptors of agonist) of Erycibele alkaloid's miosis is 3.60 +/- 0.15 and its IOP lowering action is 3.49 +/- 0.07. In the isolated iris contracting experiment, its pD(2) value is 6.38 +/- 0.12. M(3) receptor antagonist is the strongest antagonist in inhibiting the miosis, IOP lowering action and isolated iris pupillary contracting action of Erycibele alkaloid. 0.01% Erycibele alkaloid can cause the decrease of cAMP and the increase of cGMP in the aqueous humor.

CONCLUSIONS

The effects of miosis and IOP lowering of Erycibele alkaloid are all mediated by M(3) receptor subtype and its signal transductive mechanism is connected with cyclic nucleotide system.

Stereoselective determination of fenfluramine enantiomers in rat liver microsomal incubates

An enantioselective assay for l- and d-fenfluramine in rat liver microsomal incubates was developed. The method involves extraction of fenfluramine from the microsomal incubates, and formation of fenfluramine diastereomeric derivatives with the chiral reagent S-(-)-N-trifluoroacetyl prolyl chloride. Separation and quantitation of the diastereomeric fenfluramine derivatives are carried out by a capillary gas chromatographic system with flame ionization detection. The assay is linear from 1 to 50 microg/ml for each enantiomer. The analytical method affords average recoveries of 92.28 and 96.44% for l- and d-fenfluramine, respectively. The limits of detection and quantitation for the method are 0.1 and 1.0 microg/ml for the l- and d-fenfluramine isomers, respectively. The reproducibility of the assay was <10% (RSD). The method allowed study of the depletion of l- and d-fenfluramine in rat liver microsomal incubates. The stereoselectivity of fenfluramine phase I metabolism was observed.

An experimental study on homoharringtonine liposome and glaucoma filtration surgery

PURPOSE

To observe the inhibitory action of homoharringtonine liposome during the healing process of wounds in the filtering sites.

METHODS

Posterior sclerectomies were performed in 14 rabbits. Postoperatively one eye of each rabbit received subconjunctival injections of HH liposome and fellow eye received saline injection in a randomized masked fashion.

RESULTS

Fourteen days after operation the IOP of experimental eyes reduced significantly (P < 0.01) as compared with the controlled eyes, and the number of remaining filtering blebs increased noticeably (P < 0.05). Pathohistological examination revealed that the number of fibroblasts per square micron in the filtering sites and the thickness of the scars in the center of the filtering sites of the experimental eyes were less than those of the controlled eyes. No serious ocular toxic and side effects were found.

CONCLUSION

This experiment suggest that homoharringtonine liposome can markedly inhibit the scar formation of filtering sites after glaucoma filtering surgery, promote the formation of filtering blebs, and provide an experimental evidence for its clinical use in future.

[Protective and therapeutic effects of intravenous-immunoglobulin on viral myocarditis]

This study was conducted to determine whether the administration of domestically manufactured intravenous-immunoglobulin (IVIG) could prevent or alleviate myocarditis in mice. Male BALB/c mice were randomized into two groups for protection group (P) and therapy group (T), and each of the two groups was subdivided into 4 groups (1, 2, 3 and c). A 7-day protocol with daily IVIG dosage of 200 mg/kg, 500 mg/kg and 1 g/kg for groups, P1, T1, P2, T2 and P3, T3 respectively was designed. In the experiment, the mice were inoculated with Coxsackie virus B3. The prevention groups (P1, P2, P3) received IVIG in the week immediately after the inoculation; the therapy groups (T1, T2, T3) received IVIG in the second week after the inoculation. All the animals were observed for 14 days. The results showed that all mice in groups P2 and P3 survived and the pathological studies revealed no myocarditis change. By the end of observation, however, 7 mice in the control group (Pc) died with severe myocarditis changes while one mouse in group P1 died with only slight inflammatory lesions in the heart. The survival rates of groups P1, P2 and P3(95%, 100% and 100%) differed significantly from the control (65%) statistically (P < 0.05). Similarly, the results of computed image analysis demonstrated that a significant difference existed between the cardiac lesions of groups P1 and Pc in severity (P < 0.05). The survival rates were 80.0%, 93.3%, 93.3% and 53.3% for groups T1, T2, T3 and Tc respectively (P < 0.05 for T2, T3 v. s. control), yet the hearts and heart/body weight ratios of T2 and T3 were significantly smaller than those of control, pathological study was supportive which showed slight (T2 and T3) or mild (T1) lesions of the heart in comparison with the control. These results demonstrate that Chinese made IVIG has definite protective and therapeutic effects on the mice infected with CVB3.

[The restoration of the "double peak" in OCT images based on inverse Wiener]

It has been found that the high reflectivity film of the reference mirror in OCT may cause a socalled "double peak effect" in the result images. To eliminate this a restoration algorithm is proposed here. The method is based on the mathematical modals of the point-spread function of OCT with consideration of double peak effect. The power spectrum of the noise and signal are estimated by the average smooth periodogram method. An inverse wiener filter algorithm, which avoids the illness condition in common inverse filter, gives the final restored images. The algorithm is also capable of the image degrading recovery due to the aberration and the band-limited spectrum.

Regulatory role of protein tyrosine phosphorylation in platelet activating factor-induced signal transduction in platelets

AIM

To study the role of protein tyrosine phosphorylation (PTP) in platelet activating factor (PAF)-induced platelet signal transduction cascade.

METHODS

Washed rabbit platelets were used to test the inhibitory effect of genistein (Gen) on platelet aggregation and serotonin secretion. Intracellular Ca2+ ([Ca2+]i) and pH (pHi) were measured by a dual wavelength fluorophotometer with Fura 2-AM and BCECF-AM. PTP was determined with a specific anti-phosphotyrosine monoclonal antibody by Western blotting.

RESULTS

Pretreatment with Gen (100 and 200 mumol.L-1) inhibited PAF (20 nmol.L-1)-stimulated platelet serotonin release by 23.7% +/- 2.0% and 41% +/- 8%, respectively. Similar inhibitory effects of Gen were observed on PAF-evoked increase of [Ca2+]i and intracellular alkalization. PAF also elicited a pronounced increase in PTP of several bands with M(r) 70,000, 60,000, 50,000, 42,000/40,000, and 34,000, which were suppressed markedly by Gen 200 and 400 mumol.L-1. Pretreatment with staurosporine (Sta) 20 nmol.L-1, BAPTA 200 mumol.L-1, and egtazic acid 2 mmol.L-1 to inhibit PKC activation, [Ca2+]i elevation, and Ca2+ influx respectively, also showed an inhibitory effects on the formation of PTP.

CONCLUSION

PTP is involved in multiple signal transduction pathways induced by PAF, on which PKC activation and calcium mobilization play a regulatory role.

Chiral gas chromatographic assay with flame ionization detection for amphetamine enantiomers in microsomal incubates

A chiral assay for amphetamine enantiomers in rat liver microsomal incubates is based on derivatization with (S)-(-)-N-(trifluoroacetyl)-prolyl chloride (S-TFPC), capillary chromatographic separation of the diastereomeric amide derivatives, and detection by a flame ionization detector. The method is capable of detecting low levels of S- or R-amphetamine. The assay is linear from 5 to 250 micrograms/mL for each enantiomer, and the limit of detection is 0.5 microgram/mL. The analytical method affords the average recoveries of 77.53 +/- 5.22% for R-amphetamine and 74.47 +/- 3.08% for S-amphetamine. The method allows the study of the metabolic depletion of S- and R-amphetamine in rat liver microsomal incubates. The time-dependent concentration of amphetamine enantiomers in rat liver microsomes was determined, and the stereoselectivity of amphetamine phase I metabolism was observed.