Patterns of retinal ganglion cell survival after brain-derived neurotrophic factor administration in hypertensive eyes of rats

We investigated the effect of brain-derived neurotrophic factor (BDNF) on retinal ganglion cell (RGC) survival after intraocular pressure (IOP) elevation at various time intervals. In adult Wistar rats, RGCs were labeled with 5% Fluorogold. Animals with 1.8-2.5-fold increase in IOP after cauterization of three episcleral vessels, were divided into three BDNF groups and three vehicle control groups, each receiving one, two or three injections. The RGC survival percentage on RGCs of the first, second and third injections were 93.9% (n = 7), 91.3% (n = 7), 82.7% (n = 5), respectively in BDNF groups; 91.6% (n = 6), 84.1% (n = 6) and 73.5% (n = 5), respectively in vehicle controls. The second and third injections of BDNF showed statistically significant survival effects. These findings demonstrated that BDNF has partial neuroprotection on RGCs in whole retina and enhances RGC survival in moderately chronic hypertensive eyes.

Inhibitory effect of evodiamine on aldosterone release by Zona glomerulosa cells in male rats

Evodiamine is a bioactive alkaloid extracted from a Chinese herb named Wu-Chu-Yu, which possesses thermoregulatory, analgesic, and cardiovascular effects. Some studies have demonstrated that evodiamine reduces blood pressure through acting on endothelium and smooth muscle cells to produce a vasodilatory effect, but whether it affects aldosterone secretion is unclear. The purpose of this study was to examine the effect of evodiamine on aldosterone release in adrenal zona glomerulosa (ZG) cells. ZG cells were isolated from the adrenal glands of adult male rats and incubated with angiotensin II (Ang II, 1x10(-7) M) and 3H-pregnenolone in the presence or absence of evodiamine (1x10(-6)-1x10(-3) M) at 37 degrees C for one hour. The concentration of aldosterone in the media was measured by a radioimmunoassay. The level of radioactivity incorporated into aldosterone and its precursors after incubation of ZG cells with 3H-pregnenolone was analyzed by thin-layer chromatography. The results demonstrated that evodiamine decreased the basal level of and Ang II-induced release level of aldosterone in rat ZG cells. Administration of evodiamine also decreased the level of radioactivity incorporated into 3H-corticosterone and 3H-aldosterone following incubation of ZG cells with 3H-pregnenolone. This suggest that evodiamine affects aldosterone release in rat adrenal glomerulosa cells by acting on Ang II-associated pathway and reducing the activity of 11 beta-hydroxylase (an enzyme which coverts deoxycorticosterone to corticosterone) during the steroidogenesis of aldosterone.

Camptothecin suppresses nitric oxide biosynthesis in RAW 264.7 macrophages

Nitric oxide is an important cellular mediator that plays a role in tumor growth and angiogenesis. The present study was conducted to evaluate whether camptothecin (CPT), a topoisomerase I inhibitor, exhibits antitumor activity through regulation the inducible nitric oxide synthase (iNOS) biosynthesis pathway. Experiment was performed on RAW 264.7 cells, a transformed macrophage-like cell line, stimulated with lipopolysaccharide (LPS) plus interferon-gamma (IFN-gamma). Incubation of RAW264.7 cells with CPT (0.1 to 10 microM) inhibited the LPS/IFN-gamma-induced nitrite accumulation in a concentration-dependent manner with an IC50 value of 0.59+/-0.07 microM. Treatment of cells with concentrations of CPT (< or =3 microM) that are not growth inhibitory or cytotoxic strongly inhibited their ability to express iNOS mRNA and iNOS protein, however, without a direct regulatory effect on iNOS activity. Time course analysis also revealed that CPT acted in a fashion similar to the transcription inhibitor actinomycin-D. Thus, the suppressant effects of CPT on LPS/IFN-gamma-stimulated NO production seemed to be mediated probably through inhibition of iNOS gene transcription. From this observation we propose that inhibition of NO biosynthesis by CPT may underlie, at least in part, the efficacy of this antitumor agent.

Effect of cyclosporine, a P-glycoprotein inhibitor, on the pharmacokinetics of cefepime in rat blood and brain: a microdialysis study

In clinical application, cefepime and cyclosporine are regularly combined in the treatment of organ transplant patients, so the interaction of these two drugs can be hypothesized. Therefore, the pharmacokinetics of cefepime alone and in combination with cyclosporine in rat using microdialysis coupled with HPLC-UV on-line system was evaluated in the study. Cefepime at three doses (20, 50, and 100 mg/kg) showed linear kinetics. After addition of cyclosporine, the mean residence time was increased from 34.9 min to 48.6 min (p<0.05, n=6), and the area under the concentration versus time curve (AUC) increased from 4775 min microg/ml to 6960 min microg/ml (p<0.01, n=6). While in the brain, AUC increased from 64.3 min microg/ml to 110.2 min microg/ml. In summary, cyclosporine (20 mg/kg) could significantly alter the simultaneously administered cefepime (50 mg/kg) unbound drug pharmacokinetic parameters in both blood and brain.

Lack of protective effect by intermittent hypoxia on MPTP-induced neurotoxicity in mice

In the study we report here, several lines of evidence support the preventive action of intermittent hypoxia against oxidative injuries in CNS. Our in vitro data showed that autooxidation and iron-induced lipid peroxidation were attenuated in cortical homogenates of intermittent hypoxia-treated animals. Furthermore, our preliminary study found that iron induced oxidative injuries were abolished in rat brain after intermittent hypoxic treatment (paper submitted). Several antioxidative defensive systems improve in response to intermittent hypoxia. Since attenuation of autooxidation and iron-induced lipid peroxidation were observed in cortical homogenates of intermittent hypoxia-treated mice, the lack of prevention by intermittent hypoxia of MPTP-induced neurotoxicity may be due to the MPTP action that is not oxidative related. Together with our previous studies, in which several antioxidants were shown to successfully prevent oxidative injuries, our data here suggest that intermittent hypoxia may offer a potential treatment for preventing CNS degenerative diseases.

Cardiac effects of the extract and active components of Radix stephaniae tetrandrae. I. Electrically-induced intracellular calcium transient and protein release during the calcium paradox

The present study was designed to compare the cardiac actions of the extract and individual components, tetrandrine (Tet) and fangchinoline (Fan), of Radix stephaniae tetrandrae (RST). We measured the electrically induced [Ca2+]i transient in single rat ventricular myocytes and protein release following perfusion with a Ca2+ free solution (the Ca2+ paradox) from the isolated perfused rat heart, both of which are known to relate to Ca2+ influx. We found that Tet inhibited both electrically induced [Ca2+]i transient and protein release during the Ca2+ paradox, while Fan had no significant effects. The RST extract containing 9% Tet and 6% Fan by weight also affected the [Ca2+]i transient, and was only slightly, though significantly, less effective/potent than Tet alone. On the other hand, RST extract had a significantly greater inhibitory effect on protein release during the Ca2+ paradox than Tet alone. The observations suggest that the RST extract, which contains a mixture of components, may have more potent effects in the heart than its main active component.

Cardiac effects of the extract and active components of radix stephaniae tetrandrae. II. Myocardial infarct, arrhythmias, coronary arterial flow and heart rate in the isolated perfused rat heart

The primary purpose of the present study was to compare the cardioprotective effects of the extract from radix stephaniae tetrandrae (RST) and its individual compounds, tetrandrine (Tet) and fanchinoline (Fan). Secondly, we also compared the cardiac effects of the individual compounds and the RST extract with those of verapamil, a classical Ca2+ channel blocker. The Langendorff isolated perfused rat heart preparation was used. Regional ischaemia and reperfusion was employed to induce myocardial infarct and arrhythmia. Infarct, arrhythmia, heart rate and coronary artery flow were determined in hearts treated with vehicle, RST extract, Tet, Fan, or verapamil. It was found that RST extract, of which only 9% was Tet, and Tet alone produced equally potent ameliorating effects on arrhythmia and infarct induced by ischaemia and reperfusion without further inhibiting ischaemia-reduced heart rate and coronary artery flow. Fan had no effects on arrhythmia and infarct induced by ischaemia and reperfusion; but it induced S-T segment elevation and further reduced heart rate and coronary artery flow during ischaemia. Verapamil also ameliorated the effects of ischaemia and reperfusion on arrhythmia and infarct. It should be noted that 1 microM verapamil, that produced comparable effects on infarct and arrhythmia to the RST extract and Tet, further inhibited heart rate during ischaemia. The results indicate that the RST extract produces equally potent cardioprotective and anti-arrhythmic effects as Tet alone. Both RST extract and Tet may be better choices for the treatment of arrhythmia and infarct induced by myocardial ischaemia and reperfusion than the classical Ca2+ channel blocker, verapamil as they do not further reduce heart rate during ischaemia.

On-line microdialysis coupled with microbore liquid chromatography with ultraviolet detection for continuous monitoring of free cefsulodin in rat blood

A microdialysis method followed by a microbore liquid chromatographic ultraviolet detection procedure has been performed for the assay of unbound cefsulodin in rat blood. A microdialysis probe was inserted into the jugular vein for blood sampling. This method involves an on-line design for submitting dialysate into the liquid chromatographic system. The chromatographic conditions consisted of a mobile phase of methanol-100 mM monosodium phosphoric acid (10:90, v/v, pH 5.0) pumped through a microbore reversed-phase column at a flow-rate of 0.05 ml/min. Detection wavelength was set at 265 nm. Microdialysis probes, being laboratory-made, were screened for acceptable in vivo recovery while chromatographic resolution and detection were validated for response linearity as well as intra- and inter-day variabilities. The method was then applied to pharmacokinetics profiling of cefsulodin in the blood following intravenous administration of cefsulodin (20 mg/kg) in rats. Pharmacokinetics were calculated from the corrected data for dialysate concentrations of cefsulodin versus time. Based on pharmacokinetic calculation, cefsulodin best fitted to a two-exponential disposition. This study provided specific pharmacokinetic information for protein-unbound cefsulodin and demonstrated the applicability of this continuous sampling method for pharmacokinetic study.

Measurement and pharmacokinetic analysis of unbound cephaloridine in rat blood by on-line microdialysis and microbore liquid chromatography

A technique involving rapid sampling of cephaloridine in rat blood was achieved using a combination of microdialysis and sensitive microbore liquid chromatography. A microdialysis probe was inserted into the jugular vein/right atrium of a Sprague-Dawley rat. Then after a real-time collection of the analyte by microdialysis, the dialysate was automatically injected into a liquid chromatographic system via an on-line injector. Following a 2 h stabilization period after the surgical procedure, cephaloridine (20 mg/kg, i.v.) was then administered via the femoral vein. Isocratic elution of cephaloridine was carried out with a mobile phase containing methanol-20 mM monosodium phosphate (25:75, v/v, pH 5.5), and the flow rate of the mobile phase was 0.05 mL/min within 10 min. Intra- and inter-assay accuracy and precision of the assay were each less than 10%. The in vivo recovery of the cephaloridine from the microdialysate was 49.7 +/- 8.0% and 42.4 +/- 8.4% for 0.5 and 1 microg/mL standards (n = 6), respectively. Based on the pharmacokinetic analysis, the elimination half-life was 32.2 +/- 8.6 min by cephaloridine administration (20 mg/kg, i.v., n = 6).

Vasorelaxing effect of coumarins from Cnidium monnieri on rabbit corpus cavernosum

Bioassay-directed fractionation led to the identification of four known coumarins, osthole (1), imperatorin (2), xanthotoxin (3), and isopimpinellin (4), from the ethanolic extract of the fruit of Cnidium monnieri (L.) Cusson. In phenylephrine (PE)-precontracted endothelium-intact rabbit corpus cavernosum, all four coumarins exhibited relaxing effect with the IC50 values for compounds 1, 2, 3, and 4 determined to be 2.14 +/- 0.73, 0.85 +/- 0.16, 1.24 +/- 0.45, and 18.4 +/- 8.10 microM, respectively. The four compounds were identified by comparison of their physical data (EIMS, 1H- and 13C-NMR) with those from published reports.

Mechanisms of relaxant action of S-petasin and S-isopetasin, sesquiterpenes of Petasites formosanus, in isolated guinea pig trachea

We investigated the mechanisms of action of S-petasin and S-isopetasin, from Petasites formosanus Kitamura which is used as a folk medicine for treating hypertension, tumors, and asthma in Taiwan. The tension changes of tracheal segments were isometrically recorded on a polygraph. S-Petasin and S-isopetasin non-competitively inhibited cumulative histamine-, and carbachol-induced contractions with an exception that S-isopetasin produced a parallel, rightward shift of the concentration-response curve of carbachol in a competitive manner. S-Petasin also non-competitively inhibited cumulative Ca(2+)-induced contractions in depolarized (K+, 60 mM; histamine, 100 microM; or carbachol, 10 microM) guinea-pig tracheas. S-Isopetasin did in depolarized (K+, 60 mM) trachea too. The nifedipine (10 microM)-remaining tension of carbachol (0.2 microM)-induced precontraction was further relaxed by S-petasin or S-isopetasin, suggesting that no matter whether either blocked VDCCs or not, S-petasin or S-isopetasin may have other mechanisms of relaxant action. The relaxant effect of S-petasin or S-isopetasin was unaffected by the presence of propranolol (1 microM), 2',5'-dideoxyadenosine (10 microM), methylene blue (25 microM), glibenclamide (10 microM), N omega-nitro-L-arginine (20 microM), or alpha-chymotrypsin (1 U/ml). However, S-petasin (100-300 microM), but not S-isopetasin, significantly inhibited cAMP-, but not cGMP-dependent PDE activity of the trachealis. The above results reveal that the mechanisms of relaxant action of S-petasin and S-isopetasin may be primarily due to its non-specific antispasmodic and antimuscarinic effects, respectively.

Calcium channel blockade in vascular smooth muscle cells: major hypotensive mechanism of S-petasin, a hypotensive sesquiterpene from Petasites formosanus

In vivo and in vitro studies were carried out to examine the putative hypotensive actions of S-petasin, a sesquiterpene extracted from the medicinal plant Petasites formosanus. Intravenous S-petasin (0.1-1.5 mg/kg) in anesthetized rats produced a dose-dependent hypotensive effect. In isolated aortic ring, isometric contraction elicited by KCl or the L-type Ca2+ channel agonist Bay K 8644 was reduced by S-petasin (0.1-100 microM), an action not affected by the cyclooxygenase inhibitor indomethacin, nitric-oxide synthase inhibitor N(omega)-nitro-L-arginine, guanylyl cyclase inhibitor methylene blue, or removal of vascular endothelium. Pretreatment with S-petasin for 10 min shifted the concentration-response curve for KCl (15-90 mM)-induced contraction to the right and reduced the maximal response. In Ca2+-depleted and high K+-depolarized aortic rings preincubation with S-petasin attenuated the Ca2+-induced contraction in a concentration-dependent manner, suggesting that S-petasin reduced Ca2+ influx into vascular smooth muscle cells (VSMCs). Moreover, in cultured VSMCs, whole-cell patch-clamp recording indicated that S-petasin (1-50 microM) inhibited the L-type voltage-dependent Ca2+ channel (VDCC) activities. Intracellular Ca2+ concentration ([Ca2+[(i)) estimation using the fluorescent probe 1-[2-(5-carboxyoxazol-2-yl)-6-aminobenzofuran-5-oxy]-2-(2'-amino-5'-methylphenoxy)-ethane-N,N,N,N-tetraacetic acid pentaacetoxymethyl ester indicated that S-petasin (10, 100 microM) suppressed the KCl-stimulated increase in ([Ca2+[(i)). Taken together, the results suggested that a direct Ca2+ antagonism of L-type VDCC in vascular smooth muscle may account, at least in part, for the hypotensive action of S-petasin.

Determination and pharmacokinetic study of unbound cefepime in rat bile by liquid chromatography with on-line microdialysis

Biliary excretion and intestinal reabsorption in enterohepatic circulation play major dispositional roles for some drugs. To investigate biliary excretion of drug, we inserted a microdialysis probe into the bile common duct of rat between the liver and the duodenum. In order to avoid the obstruction of bile fluid or bile salt waste, a shunt linear microdialysis probe was used for simultaneous and continuous sampling following intravenous administration of cefepime (50 mg/kg, i.v.). Separation and quantitation of cefepime in the dialysates were achieved using a LiChrosorb RP-18 column (Merck; 250x4.6 mm I.D., particle size 5 microm) maintained at ambient temperature. Samples were eluted with a mobile phase containing 100 mM monosodium phosphoric acid (pH 3.0)-methanol (87:13, v/v). The UV detector wavelength was set at 270 nm. The result indicates that the elimination half-life of cefepime in bile was 64.01+/-9.32 min. This study also served as an example for the microdialysis application in the biliary excretion study of drug.

Renal response during acute unilateral ureteral obstruction in rats

The early renal response to unilateral ureteral occlusion (UUO) and its mechanism have been extensively studied in dogs but seldom discussed in the most frequently used laboratory animals, rats. The acute phase of the renal response to UUO was studied in female rats weighing 190-236 g. We recorded the ureteral pressure and changes in renal parameters throughout 120 minutes of UUO in control (US, UUO + saline, n = 10), L-arginine-treated (UA, n = 10), and right-nephrectomized rats (UO, UUO in one kidney, n = 9). Ureteral pressure increased in all three groups of rats after complete ureteral obstruction. The extent of the increase was not significantly different between US and UA rats but was significantly higher in the UO rats. In US rats, the cortical microvascular blood flow (CMVBF), measured by a laser Doppler flowmeter, declined significantly, from 321 +/- 10 perfusion units (PU) to 260 +/- 11 PU. The percentage of drop in CMVBF at 120 minutes of UUO was significantly greater in UO (25.7 +/- 3.8 %) than in US (19 +/- 2.1%) and in UA (14 +/- 2%) rats. Acute UUO reduced the glomerular filtration rate (GFR) in US and UO rats, whereas L-arginine attenuated this decrease. The excretion of nitrate/nitrite was increased after UUO. Giving N(G)-nitro-L-arginine methyl ester hydrochloride (L-NAME, 12 mg/kg/h) during UUO did not reduce CMVBF more severely. Western blot analysis of endothelial nitric oxide synthase expression in the renal cortex and medulla protein extracts revealed no differences between US and sham-operated rats. Acute UUO did not lead to renal hyperemia in rats. Reduction of nitric oxide during UUO might contribute to the decrease of renal circulation during UUO.

Prevalence and relationship between allergic diseases and infectious diseases

In order to determine the prevalence of childhood allergic diseases, infectious diseases, and the relationship between them, 8723 children from three junior high schools in Tou-Cheng City, Taipei County, were studied using questionnaires developed according to the International Study of Asthma and Allergies in Childhood (ISAAC) criteria combined with supplementary questions about infectious diseases. Students and their parents completed the questionnaires at home. The age of the children ranged from 10 to 18 years old (14.12 +/- 0.89 years), the majority (96.03%) was aged from 13 to 15 years old. The 12-month prevalences of self-reported allergic disease symptoms were: asthma symptom 8.2%, allergic rhinitis symptom 39.6%, and atopic dermatitis symptom 5.9%. The prevalences of diagnosis of the allergic diseases were: asthma 8.7%, allergic rhinitis 24.1%, and atopic dermatitis 3.9%. The 12-month prevalences of diagnosis of infectious diseases were: pneumonia 0.6%, bronchitis 7.2%, sinusitis 7.2%, purulent conjunctivitis 2.5%, otitis media 4.3%, encephalitis or meningitis 0.4%, gastroenteritis 14.5%, acne 23.9%, purulent dermatitis 1.3%, and other infectious diseases 1.2%. Lifetime admission rates of children due to infectious diseases were: pneumonia 1%, bronchitis 1.8%, sinusitis 0.3%, purulent conjunctivitis 0.2%, otitis media 0.3%, encephalitis or meningitis 0.3%, gastroenteritis 2.1%, and other infectious diseases 0.6%. The prevalence of infectious diseases was significantly higher in children with allergic disease symptoms (defined as asthma, allergic rhinitis, or atopic dermatitis). These results demonstrated the presence of a link between allergic diseases and infectious diseases, which may have some important clinical implications.

Comparative study on the vasorelaxant effects of three harmala alkaloids in vitro

Three psychological active principles from the seeds of Peganum harmala L., harmine, harmaline and harmalol, showed vasorelaxant activities in isolated rat thoracic aorta preparations precontracted by phenylephrine or KCl with rank order of relaxation potency of harmine > harmaline > harmalol. The vasorelaxant effects of harmine and harmaline (but not harmalol) were attenuated by endothelium removal or pretreatment with a nitric oxide (NO) synthase Nomega-nitro-L-arginine methyl ester. In cultured rat aortic endothelial cells, harmine and harmaline (but not harmalol) increased NO release, which was dependent on the presence of external Ca2+. In endothelium-denuded preparations, pretreatment of harmine, harmaline or harmalol (3-30 microM) inhibited phenylephrine-induced contractions in a non-competitive manner. Receptor binding assays indicated that all 3 compounds interacted with cardiac alpha1-adrenoceptors with comparable affinities (Ki value around 31 - 36 microM), but only harmine weakly interacted with the cardiac 1,4-dihydropyridine binding site of L-type Ca2+ channels (Ki value of 408 microM). Therefore, the present results suggested that the vasorelaxant effects of harmine and harmaline are attributed to their actions on the endothelial cells to release NO and on the vascular smooth muscles to inhibit the contractions induced by the activation of receptor-linked and voltage-dependent Ca2+ channels. The vasorelaxant effect of harmalol was not endothelium-dependent.

The neuroprotective effects of phytoestrogens on amyloid beta protein-induced toxicity are mediated by abrogating the activation of caspase cascade in rat cortical neurons

Amyloid beta protein (Abeta) elicits a toxic effect on neurons in vitro and in vivo. In present study we attempt to elucidate the mechanism by which Abeta confers its neurotoxicity. The neuroprotective effects of phytoestrogens on Abeta-mediated toxicity were also investigated. Cortical neurons treated with 5 microm Abeta-(25-35) for 40 h decreased the cell viability by 45.5 +/- 4.6% concomitant with the appearance of apoptotic morphology. 50 microm kaempferol and apigenin decreased the Abeta-induced cell death by 81.5 +/- 9.4% and 49.2 +/- 9.9%, respectively. Abeta increased the activity of caspase 3 by 10.6-fold and to a lesser extent for caspase 2, 8, and 9. The Abeta-induced activation of caspase 3 and release of cytochrome c showed a biphasic pattern. Apigenin abrogated Abeta-induced cytochrome c release, and the activation of caspase cascade. Kaempferol showed a similar effect but to a less extent. Kaempferol was also capable of eliminating Abeta-induced accumulation of reactive oxygen species. These two events accounted for the remarkable effect of kaempferol on neuroprotection. Quercetin and probucol did not affect the Abeta-mediated neurotoxicity. However, they potentiated the protective effect of apigenin. Therefore, these results demonstrate that Abeta elicited activation of caspase cascades and reactive oxygen species accumulation, thereby causing neuronal death. The blockade of caspase activation conferred the major neuroprotective effect of phytoestrogens. The antioxidative activity of phytoestrogens also modulated their neuroprotective effects on Abeta-mediated toxicity.

Dehydroevodiamine attenuates beta-amyloid peptide-induced amnesia in mice

Dehydroevodiamine has been reported to have anticholinesterase activity and an anti-amnesic effect. This study examined the effects of dehydroevodiamine on scopolamine- and beta-amyloid peptide-(25--35)-induced amnesia in mice, using a step-through passive avoidance test. Similarly to the cholinesterase inhibitor, physostigmine (0.03--0.3 mg/kg, i.p.), dehydroevodiamine (0.75--12.0 mg/kg, i.p.) administered 30 min before the training trial, immediately after the training trial, and 30 min before the retention test significantly improved scopolamine- and beta-amyloid peptide-(25--35)-induced amnesia. In beta-amyloid peptide-(25--35)-induced amnesia, the rank order of anti-amnesic potency in these three administration schedules for dehydroevodiamine was different from that for physostigmine. Furthermore, dehydroevodiamine was more potent to improve beta-amyloid peptide-(25--35)-induced amnesia than scopolamine-induced amnesia when administered before the training trial. These results suggested that dehydroevodiamine may have an action other than that of an anticholinesterase and may be a novel and effective ligand for improvement of beta-amyloid type amnesia.

Measurement and pharmacokinetic analysis of unbound ceftazidime in rat blood using microdialysis and microbore liquid chromatography

To evaluate the biodisposition of ceftazidime in rat blood, a rapid and simple microbore liquid chromatographic technique together with a microdialysis sampling technique were developed. This method involves an on-line design for blood dialysate directly injected into a microbore liquid chromatographic system. The chromatographic conditions consisted of a mobile phase of methanol-acetonitrile-100 mM monosodium phosphoric acid (pH 3.0) (10:10:80, v/v/v) pumped through a microbore reversed-phase column at a flow-rate of 0.05 ml/min. With the detection wavelength set at 254 nm, a good linear correlation was observed between the peak area and the ceftazidime concentration at 0.1 to 50 microg/ml (r=0.999). Microdialysis probes, being custom-made, were screened for acceptable in vivo recovery while chromatographic resolution and detection were validated for response linearity, as well as intra-day and inter-day variabilities. This method was then applied to the pharmacokinetic profiling of ceftazidime in blood following intravenous 50 mg/kg administration to rats. The pharmacokinetics was calculated from the corrected data for dialysate concentrations of ceftazidime versus time. This method has been used to study ceftazidime pharmacokinetics in rats and has proven to be rapid and reproducible.

Anti-hepatitis B virus effects of wogonin isolated from Scutellaria baicalensis

By using an HBV-producing cell line (MS-G2) in vitro culture system, we found that wogonin isolated from Scutellaria baicalensis can suppress HBV surface antigen production (P < 0.001) without evidence of cytotoxicity. By assaying the endogenous HBV DNA polymerase activity, we found that both the relaxed circular and the linear forms of HBV DNA are significantly reduced in the wogonin-treated group. Wogonin deserves to be further evaluated for the treatment of human HBV infection.

Effects of extracted Cordyceps sinensis on steroidogenesis in MA-10 mouse Leydig tumor cells

Extracts from the mycelium of Cordyceps sinensis (CS) were tested to determine the in vitro effect on Leydig cell function. MA-10 mouse Leydig tumor cells were used to conduct the experiments. Results showed that progesterone production gradually increased as the dosage of combined water and ethanol extracted CS increased, and there was a statistically significant difference in progesterone production stimulated by 20 mg/ml of CS extracts compared to the control. The combined water and ethanol extracted CS significantly stimulated MA-10 cell steroid production at 12 and 24 h of incubation. In addition, a protein synthesis inhibitor, cycloheximide, did not block the stimulatory effects of CS extracts on MA-10 cell steroid production or total protein expression. Moreover, the expression of steroidogenic acute regulatory (StAR) protein, which is a critical protein for steroidogenesis, stimulated by CS extracts, could not be detected by Western blot analysis. These data indicate that CS extracts might not induce StAR protein and/or other protein expressions to stimulate steroidogenesis in MA-10 mouse Leydig tumor cells.

Anticonvulsant effect of water extract of Scutellariae radix in mice

Since a previous study indicated that the water extract of Scutellariae radix (SR) had high affinity for the benzodiazepine (BDZ) binding site of GABA(A) receptors, the present study examined whether SR water extract has an anticonvulsant effect in vivo and an enhancing effect on gamma-amino-n-butyric acid (GABA)-stimulated uptake of 36Cl(-) in cortex preparation in vitro in mice. The results showed that SR water extract had little effect on pentylenetetrazol (PTZ, 85 mg/kg, s.c.)-induced clonic seizures but significantly inhibited maximal electroshock-induced tonic seizures with an ED(50) of 3.6 g/kg. The BDZ agonist chlordiazepoxide (10 mg/kg, i.p.) had anticonvulsant activity on both types of seizures. In 36Cl(-) uptake assay, SR water extract (1-500 microg/ml) had no significant effect on 25 microM GABA-stimulated 36Cl(-) uptake, whereas chlordiazepoxide (10 microM) increased the 36Cl(-) uptake to 125% of control. Therefore, the present results showed for the first time that SR water extract had anticonvulsant activity against maximal electroshock-induced tonic seizures, and suggested that this anticonvulsant effect might be not via the activation of the BDZ binding site of GABA(A) receptors, but probably via the prevention of seizure spread.

Anti-diarrheal effect of water extract of Evodiae fructus in mice

Our previous study showed that Evodiae fructus (the dried, unripe fruit of Evodia rutaecarpa) has an inhibitory effect on the intestinal transit (anti-transit effect) in mice. In the present study, a water extract of Evodiae fructus was used to examine its effect on castor oil-induced diarrhea and to compare with its anti-transit effect in mice. The results indicated that Evodiae fructus had both anti-transit and anti-diarrheal effects with comparable ID(50) (the dose for 50% inhibition) values of 54+/-7 and 76+/-17 mg/kg. The time-courses of Evodiae fructus pretreatment for both anti-transit and anti-diarrheal effects were very similar. Because no significant influences of both nitric oxide (NO) precursor L-arginine (600 mg/kg, i.p.) and NO synthase inhibitor N(G)-nitro-L-arginine methyl ester (25 mg/kg, i.p.) pretreatment, the NO system was not involved in both the anti-transit and anti-diarrheal effects of Evodiae fructus. Like Evodiae fructus, a muscarinic acetylcholine receptor antagonist atropine inhibited castor oil-induced increase in fecal weight and loss of body weight. However, the potencies or time-courses of atropine pretreatment for both anti-transit and anti-diarrheal effects were different. Furthermore, the anti-diarrheal effect of atropine was independent of its anti-transit effect at the lower dose (0.5 mg/kg, i.p.). Therefore, the action of Evodiae fructus appeared to be something different from atropine, suggesting that an action other than the anti-muscarinic action, as previously proposed for Evodiae fructus, may be involved.