Building the Hospital Without Walls--a CSIRO home telecare initiative

Aging populations and rising health costs have created the need to care for more patients in their own homes. Australia's Commonwealth Scientific and Industrial Research Organization (CSIRO) is developing a project, Hospital Without Walls, which aims to provide continuous monitoring of patients in certain diagnostic categories. The key technology is a miniature, wearable, low-power radio that can transmit vital sign and activity information to a home computer, from which data may be sent by telephone line and the Internet to appropriate medical professionals. The initial clinical scenario for this work is monitoring of elderly patients who have presented to hospitals following repeated falls. Accelerometers built into the radio sets will monitor activity and detect and characterise falls. Simultaneous measurement of heart rate will provide information about abnormalities of cardiovascular physiology at the time of a fall. The system has been tested in laboratory conditions and is being adapted for initial clinical trials.

Relaxant effects of petasins in isolated guinea pig trachea and their structure-activity relationships

In the present study, we attempted to compare four petasins, isolated from Petasites formosanus Kitamura, and to look for structure-activity relationships, which may be helpful for synthesizing more active compounds for the treatment of asthma. Four petasins, including petasin, isopetasin, S-petasin and S-isopetasin, concentration-dependently relaxed histamine (10 microM)-, carbachol (0.2 microM)-, KCl (30 mM)-, and leukotriene D4 (10 nM)-induced precontractions of isolated guinea pig trachealis. The IC50 values strongly showed that the relaxant effects of the sulfur-containing petasins, S-petasin and S-isopetasin, were more potent than those of non-sulfur-containing petasins, petasin and isopetasin. S-isopetasin, with IC50 values around 10 microM, selectively relaxed carbachol- and KCl-induced precontractions, and had almost no effects (IC50s > 300 microM) on histamine- and leukotriene D4-induced precontractions. However, S-petasin, with IC50 values about 6-9 microM, non-selectively relaxed the precontractions induced by all these contractile agents. The influence of isomerization of either petasin to isopetasin or S-petasin to S-isopetasin on the relaxant effects is not clear.

Regulation of gli activity by all-trans retinoic acid in mouse keratinocytes

Sonic hedgehog (Shh) signaling is essential for many normal developmental processes. The Shh signal is interpreted by the Gli transcription factors. Elevated Gli-1 expression has been associated with several neoplasms, including basal cell carcinoma. All-trans retinoic acid (RA) has strong effects on epidermal growth and differentiation and has been used for the treatment of various epithelial disorders. In this report, we show that RA can inhibit Gli activity in immortalized murine keratinocytes in a RA receptor-specific manner. This inhibition may occur, at least in part, through sequestration of the transcriptional coactivator cyclic AMP-responsive element-binding protein-binding protein and suggests a novel effect of retinoid excess on Shh signaling.

Inhibition of testosterone secretion by S-petasin in rat testicular interstitial cells

S-petasin, a kind of sesquiterpene ester, is the anti-inflammatory ann analgesic component of the butterbur (Petasites hybridus). The clinical benefit of S-petasin is the spasmolytic activity, but its side effects on the reproductive endocrinology are not clear yet. The present study was to explore the effects of S-petasin on the secretion of testosterone in vivo and in vitro. We found that single intravenous injection of S-petasin (1 microg/kg) decreased basal plasma testosterone concentration in adult male rats. The enzymatically dispersed rat testicular interstitial cells were incubated with S-petasin (0-4.3 x 10(-5)M) in the presence or absence of human chorionic gonadotropin (hCG, 0.05 IU/ml), forskolin (adenylyl cyclase activator, 10(-5) M), and androstenedione (testosterone biosynthesis precursor, 10(-9) M) at 34 degrees C for 1 h. The concentrations of testosterone in the incubation medium were measured by radioimmunoassay. S-petasin at 4.3 x 10(-7) M was effective to reduce the basal and hCG-stimulated release of testosterone in rat testicular interstitial cells. The stimulatory effects of testosterone secretion induced by forskolin and androstenedione were significantly reduced by S-petasin at 4.3 x 10(-5) M and 4.3 x 10(-6) M, respectively. These results suggest that S-petasin inhibits the production of testosterone in rat testicular interstitial cells in part through diminishing the activities of adenylyl cyclase and 17-ketosteroid reductase.

Effects of baicalein and wogonin on drug-metabolizing enzymes in C57BL/6J mice

Effects of baicalein and wogonin, the major flavonoids of Scutellariae radix, on cytochrome P450 (CYP), UDP-glucuronosyl transferase (UGT), and glutathione S-transferase (GST) were studied in C57BL/6J mice. One-week treatment of mice with a liquid diet containing 5 mM baicalein resulted in 29%, 14%, 36%, 28%, and 46% decreases of hepatic benzo(a)pyrene hydroxylation (AHH), benzphetamine N-demethylation (BDM), N-nitrosodimethylamine N-demethylation (NDM), nifedipine oxidation (NFO), and erythromycin N-demethylation (EMDM) activities, respectively. Treatment with a liquid diet containing 5 mM wogonin resulted in 43%, 22%, 21%, 24%, and 35% decreases of hepatic AHH, BDM, NDM, NFO, and EMDM activities, respectively. However, hepatic 7-methoxyresorufin O-demethylation (MROD) activity was increased and decreased by baicalein- and wogonin-treatments, respectively. Similar modulation was observed with caffeine 3-demethylation (CDM) activity. Immunoblot analysis showed that the levels of hepatic CYP2E1 and CYP3A proteins were decreased by both baicalein- and wogonin-treatments. Hepatic CYP1A2 protein level was increased by baicalein but decreased by wogonin. In extrahepatic tissues, renal AHH activity was decreased by wogonin whereas pulmonary AHH, 7-ethoxyresorufin O-deethylation (EROD), and MROD activities were increased by both flavonoids. Both baicalein and wogonin strongly increased CYP1A protein level in mouse lung. Hepatic and renal UGT activities toward p-nitrophenol were suppressed by baicalein- and wogonin-treatments. However, cytosolic GST activity was not affected by flavonoids. These results suggest that ingestion of baicalein or wogonin can modulate drug-metabolizing enzymes and the modulation shows tissue specificity.

Simultaneous determination of unbound cefoperazone in rat blood and brain using microdialysis

A sensitive microbore HPLC method was developed for the simultaneous determination of unbound cefoperazone in rat blood and brain using microdialysis. Two microdialysis probes were inserted into the jugular vein/right atrium and brain striatum of Sprague-Dawley rats. Cefoperazone (50 mgkg(-1), i.v.) was then administered via the femoral vein. Blood and brain dialysates were collected and eluted with a mobile phase containing methanol-100 mM monosodium phosphoric acid (30:70, v/v, pH 5.5). The wavelength of the UV detector was set at 254 nm. The detection limit of cefoperazone was 20 ng mL(-1). Isocratic separation of cefoperazone was achieved within 10 min. The intra- and inter-assay accuracy and precision of the analyses were < or =10% in the range of 0.05-10 microg mL(-1). The ratio of the area under the concentration curve of cefoperazone in rat brain and blood was estimated to be about 7-8%. It is concluded that cefoperazone is capable of penetrating the blood-brain barrier.

Mediation of cell-substratum adhesion by RasG in Dictyostelium

Previous studies on the functions of the RasG gene in the cellular slime mold, Dictyostelium discoideum, have revealed that it is required for normal motility and cytokinesis. To further understand how the RasG gene regulates various cellular processes, we transformed an activated form of RasG, that is, RasG (G12T), a mutation from glycine to threonine at amino acid position 12 into wild type KAX-3 cells. This produced moderate but constitutive RasG(G12T) protein expression, which causes cells to become significantly more adherent to the substratum than are wild type cells. The RasG(G12T) transformants also grow slowly on bacterial plates, and engulf fewer bacteria on filter surfaces, indicating a defect in phagocytosis when cells are adhered. The expression of the activated RasG also dramatically reduces the number of filopodia on the cell surface. Tyrosine phosphorylation on a 43 kDa protein (most likely actin) of the RasG (G12T) transformants is highly elevated. Taken together, our observations suggest that RasG is crucial for Dictyostelium cell-substratum adhesion during growth and that RasG may play a role in adhesion-mediated phagocytosis. Our results also suggest that RasG is important in filopodial formation and that RasG is involved in the signal pathway that is regulated by tyrosine phosphorylation.

Reduction in renal haemodynamics by exaggerated vesicovascular reflex in rats with acute urinary retention

1. We examined the possibility that a vesicovascular reflex is exaggerated by acute urinary retention, and that the increase in renal vascular resistance caused by this reflex may lead to renal dysfunction. We evaluated the vesicovascular responses to normal micturition (NM, transcystometric condition) and acute urinary retention (isovolumetric condition mimicking complete bladder-outlet obstruction (CBOO) and partial urethral ligation mimicking partial bladder-outlet obstruction (PBOO)) in anaesthetized female Wistar rats. 2. Acute urinary retention due to CBOO or PBOO provoked a prolonged or increased intravesical pressure, an enhancement in both bladder pelvic afferent and bladder pelvic efferent nervous activity, and an elevation in mean arterial blood pressure. 3. Single-unit analysis showed that these vesicovascular reflexes were triggered by activation of low-threshold and high-threshold bladder mechanoreceptors, but not by renal uretropelvic mechanoreceptors. 4. Bladder contraction in CBOO and PBOO conditions and graded increases in bladder volume significantly reduced renal blood flow and cortical microvascular blood flow. The acute urinary retention-induced renal vasoconstriction was mediated by the renal nerve. Renal denervation, but not bilateral ureteral resection, abolished the renal vasoconstriction associated with the vesicovascular reflexes. 5. These findings indicate that exaggerated activation of bladder afferents exerts a positive feedback effect to increase sympathetic outflow to the kidney further, thereby contributing to significant renal vasoconstriction via a renal nerve-dependent mechanism.

A novel agarofuran sesquiterpene, celahin D from Celastrus hindsii Benth

A novel agarofuran sesquiterpene polyol ester, 1beta,2beta,6alpha,15beta-tetracetoxy-8 beta,9alpha-dibenzoyloxy-beta- dihydroagarofuran (celahin D) (1), two known analogues of 1,1beta-acetoxy-8beta,9alpha-dibenzoyloxy-4al pha6alpha-dihydroxy-2beta(alphamethylbutanoyloxy)-beta-++ +dihydroagarofuran (2) and beta-acetoxy-8beta,9alpha-dibenzoyloxy-6alpha-hy droxy-2beta(alpha -methylbutanoyloxy)-beta-dihydroagarofuran (3), and a known cytotoxic sesquiterpene pyridine alkaloid, emarginatine E (4) were isolated from the stems of Celastrus hindsii Benth. Three known triterpenes, loranthol (5), lupenone (6) and friedelinol (7) were also obtained from the titled plant. Structural elucidation of compound 1 was established by 2D NMR spectra.

Possible biphasic changes of free radicals in ethylene glycol-induced nephrolithiasis in rats

OBJECTIVE

To evaluate the possible role of free radicals in nephrolithiasis in rats induced by ethylene glycol, and to examine the correlation between the urinary enzymes N-acetyl-beta-glucosaminidase (NAG), beta-galactosidase (GAL) and neutral endopeptidase (NEP), and free radical production.

MATERIALS AND METHODS

Hyperoxaluria was produced in male Wistar rats by adding ethylene glycol to their drinking water. After 7, 21 and 42 days of treatment, urinary oxalate, creatinine clearance and urinary enzymes (NAG, GAL and NEP) were measured. The nitroblue tetrazolium perfusion method was used to locate the sites of free-radical production. Ultrasensitive chemiluminescence was used to directly measure the production of reactive oxygen species (ROS) in vivo. Vitamin E and potassium citrate were fed to rats, in addition to ethylene glycol, to assess their effects on free radical production.

RESULTS

Urinary oxalate increased significantly and was associated with an increase in NAG and GAL at all sample times. However, urinary NEP activity was unchanged on day 7, although there was four times as much NEP on days 21 and 42 than in the control groups. Formazan particles in the renal cortex were scored as 3+ to 4+ in rats treated for 7 days with ethylene glycol. Blood ROS levels were also higher in this group than in the controls (P < 0.01). After vitamin E and potassium citrate treatment, blood ROS levels were lower than in rats treated with ethylene glycol alone.

CONCLUSION

Free radicals may be produced in the early stages of nephrolithiasis in rats fed with ethylene glycol. Free radicals occurred mainly in blood and might be associated with NEP inactivation.

Effect of the plant-extract osthole on the relaxation of rabbit corpus cavernosum tissue in vitro

PURPOSE

We investigated the cavernosal relaxant effect of osthole, a coumarin isolated from Cnidium monnier (L.) Cusson which has been long used in China as a herbal medicine to improve male sexual dysfunction.

MATERIALS AND METHODS

Strips of rabbit corpus cavernosum were precontracted with phenylephrine. Corporal relaxation evoked by osthole was then determined in the absence and presence of nitric oxide synthase inhibitor (L-NAME), soluble guanylate cyclase inhibitor (ODQ), cyclooxygenase inhibitor (indomethacin), tetradotoxin, and after endothelium deprivation.

RESULTS

Corpus cavernosal strips showed relaxation in response to osthole (0.1 approximately 30 microM) in a dose-dependent manner. These effects were reduced partially but significantly by pretreatment with L-NAME, ODQ and by endothelial disruption. However, they were not affected by indomethacin and tetradotoxin treatment. Osthole pretreatment (from 1 to 30 microM) enhanced the sodium nitroprusside (0.3 microM)-induced relaxation of corpus cavernosum in a dose-dependent manner to a maximum of 3 times the pretreatment level at 30 microM osthole. However, this effect was abolished in the presence of zaprinast. Additionally, a higher concentration of osthole (30 microM) also enhanced forskolin-induced relaxation.

CONCLUSION

The data suggested that osthole possesses a relaxant effect on rabbit corpus cavernosal tissues which is attributable to the release of NO from sinusoidal endothelium and to the potentiation of the cGMP and/or cAMP signal mediating relaxation of cavernosal smooth muscle by inhibiting phosphodiesterase.

Determination of unbound cephalothin in rat blood by on-line microdialysis and microbore liquid chromatography

A method of analysis for the determination of unbound cephalothin in rat blood has been developed. The method was fully automated using an on-line microdialysis procedure. A microdialysis probe was inserted into the jugular vein/right atrium of male Sprague-Dawley rats to examine the unbound cephalothin level in the rat blood after cephalothin administration (50 mg/kg, i.v.). Dialysates were directly input to a liquid chromatographic system using an on-line injector. Samples were eluted with a mobile phase containing methanol-acetonitrile-100 mM monosodium phosphate (pH 5.0) (20:20:60, v/v). The UV wavelength was set at 254 nm for monitoring the analyte. Using the retrograde method, at infusion concentrations of 1 and 5 microg/ml of cephalothin, the in vivo microdialysis recoveries were 48.4+/-4.5% and 52.9+/-4.7% for the rat blood (n=6). Intra- and inter-assay accuracy and precision of the analyses were < or = 10% in the range of 0.01 through 10 microg/ml. Pharmacokinetic parameters were calculated from the recovery corrected dialysate concentrations of cephalothin versus time data. The results suggest that the pharmacokinetics of unbound cephalothin in blood fitted best to the two-compartmental model following cephalothin administration (50 mg/kg, i.v.).

Suppression of rat neutrophil reactive oxygen species production and adhesion by the diterpenoid lactone andrographolide

The present study was to examine whether andrographolide, a diterpenoid lactone isolated from the anti-inflammatory herbal medicine Andrographis paniculata (Burm. f.) Nees. (Acanthaceae), has the ability to prevent phorbol-12-myristate-13-acetate (PMA)-induced reactive oxygen species (ROS) production, as well as N-formyl-methionyl-leucyl-phenylalanine (fMLP)-induced adhesion by rat neutrophils. Results demonstrated that PMA (100 ng/ml) induced rapid accumulation of H2O2 and O2. in neutrophils within 30 minutes. Andrographolide (0.1 to 10 microM) pretreatment (10 min, 37 degrees C) significantly attenuated the accumulation of these two oxygen radical metabolites. Administration of andrographolide also significantly prevented fMLP-induced neutrophil adhesion. These data suggest that preventing ROS production and neutrophils adhesion may confer andrographolide the ability to be an anti-inflammatory drug.

Neural mechanisms of impaired micturition reflex in rats with acute partial bladder outlet obstruction

To determine the contribution of neural elements to micturition, we evaluated, in intact rats, the cystometrogram, pelvic afferent nervous activity, pelvic efferent nervous activity and external urethral sphincter-electromyogram activity in the normal and acute partial bladder outlet obstruction states. In the normal state, in response to saline filling, mechanoreceptor-dependent pelvic afferent nervous activity gradually activated and finally triggered a voiding reflex, including four phases of detrusor contractions. Phase 1 was characterized by an initial rising intravesical pressure, Phase 2 was characterized by a series of high-frequency oscillations in intravesical pressure, Phase 3 contraction was characterized by a rebound intravesical pressure and Phase 4 contraction was characterized by a rapid fall in intravesical pressure. In the acute partial bladder outlet obstruction state, Phase 1 contraction rose and high-frequency oscillations fell in Phase 2. This voiding dysfunction is ascribed to the bursting extraurethral sphincter activity being converted to tonic extraurethral sphincter activity. In summary, the suppressed high-frequency oscillations in Phase 2 of the detrusor muscle contraction could be detrimental to efficient voidings in the acute partial bladder outlet obstructed rat.

Simultaneous blood and brain sampling of cephalexin in the rat by microdialysis and microbore liquid chromatography: application to pharmacokinetics studies

To circumvent the need for laborious sample clean-up and multiple blood sampling, a system was developed consisting of on-line microdialysis coupled to microbore liquid chromatography and ultraviolet detection. The system was designed for the simultaneous and continuous monitoring of unbound blood and brain cephalexin in the rat following single bolus intravenous administrations (10 mg/kg, n = 6). Microdialysis probes were inserted into the jugular vein and brain striatum, respectively, for blood and brain sampling. Chromatographic conditions consisted of a mobile phase of methanol-100 mM monosodium phosphoric acid (20:80, 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 260 nm. The method was validated for response linearity as well as intra- and inter-day variabilities. Rapid appearance of cephalexin in the striatal dialysate suggested good blood-brain barrier penetration. This study provided pharmacokinetics information for cephalexin as well as demonstrated the applicability of this continuous sampling method for pharmacokinetics studies.

Mechanisms of suppression of inducible nitric oxide synthase (iNOS) expression in RAW 264.7 cells by andrographolide

Andrographolide, an active component found in leaves of Andrographis paniculata, has been reported to exhibit nitric oxide (NO) inhibitory property in endotoxin-stimulated macrophages, however, the detailed mechanisms remain unclear. In the present study we investigated the effect of andrographolide on the expression of inducible NO synthase (iNOS) mRNA, protein, and enzyme activity in RAW 264.7 macrophages stimulated with lipopolysaccharide (LPS) plus interferon-gamma (IFN-gamma). RAW 264.7 cells stimulated with LPS/IFN-gamma activated NO production; in this condition andrographolide (1-100 microM) inhibited NO production in a dose-dependent manner with an IC(50) value of 17.4+/-1.1 microM. Andrographolide also reduces the expression of iNOS protein level but without a significant effect on iNOS mRNA. The reduction of iNOS activity is thought to be caused by decreased expression of iNOS protein. In a protein stability assay, andrographolide moderately but significantly reduced the amount of iNOS protein as suggested by accelerating degradation. Furthermore, andrographolide also inhibited total protein de novo synthesis as demonstrated by [(35)S]-methionine incorporation. As a whole, these data suggest that andrographolide inhibits NO synthesis in RAW 264.7 cells by reducing the expression of iNOS protein and the reduction could occur through two additional mechanisms: prevention of the de novo protein synthesis and decreasing the protein stability via a post-transcriptional mechanism. It is also possible that inhibition of iNOS protein expression and NO production under immune stimulation and/or bacteria infection may explain, in part, the beneficial effects of andrographolide as an anti-inflammatory agent.

Aerosolized Syk antisense suppresses Syk expression, mediator release from macrophages, and pulmonary inflammation

Syk protein tyrosine kinase (PTK) is involved in signaling in leukocytes. In macrophages, Fcgamma-receptor cross-linking induces Syk PTK phosphorylation and activation, resulting in Syk-dependent events required for phagocytosis and mediator release. We hypothesized that Syk antisense oligodeoxynucleotides (ASO) delivered by aerosol to rat lungs in vivo would depress Syk PTK expression, mediator release from alveolar macrophages, and Syk-dependent pulmonary inflammation. RT-PCR and RT-in situ PCR demonstrated that aerosolized Syk ASO administration reduced Syk mRNA expression from alveolar macrophages compared with cells isolated from sham-treated rats. Western blot analysis confirmed that Syk PTK expression was reduced after Syk ASO treatment. Compared with sham-treated rats (scrambled oligodeoxynucleotide), Syk ASO treatment suppressed Fcgamma-receptor-mediated nitric oxide (86.0 +/- 8.3%) and TNF (73.1 +/- 3.1%) production by alveolar macrophages stimulated with IgG-anti-IgG complexes. In contrast, Fcgamma-receptor-induced IL-1beta release was unaffected by Syk ASO treatment. Additionally, Syk ASO suppressed Ag-induced pulmonary inflammation, suggesting that Syk ASO may prove useful as an anti-inflammatory therapy in disorders such as asthma.

Enterohepatic circulation of chloramphenicol and its glucuronide in the rat by microdialysis using a hepato-duodenal shunt

A system consisting of a hepato-duodenal shunt in which the bile of a drug-treated donor rat was diverted to the duodenum of an untreated recipient rat via a bile cannula was used to assess the role of hepatic metabolism and enterohepatic circulation in the pharmacokinetics of chloramphenicol. Blood concentrations of unbound chloramphenicol and its glucuronide were measured by on-line microdialysis coupled to a microbore liquid chromatographic system. Results indicated that chloramphenicol and its glucuronide were detected in the blood of both donor and recipient rats following an intravenous 100 mg/kg dose of chloramphenicol succinate to the donor rat. Our finding suggests that although enterohepatic circulation contributed only to a minor extent (approximately 1.8%) was involved in the disposition of unbound chloramphenicol in the rat on-line microdialysis techniques were applicable for such studies.

Vasorelaxant effect of harman

The in vivo cardiovascular effect and in vitro vasorelaxant effect of harman, one of harmala alkaloids isolated from Peganum harmala, were examined in this study. Harman (1-10 mg/kg, i.v.) dose-dependently produced transient hypotension and long-lasting bradycardia in pentobarbital-anesthetized rats, which were attenuated by N(G)-nitro-L-arginine pretreatment. In isolated rat endothelium-intact thoracic aortic rings, harman concentration dependently relaxed phenylepherine-induced contractions with an IC(50) value around 9 microM. This vasorelaxant effect was attenuated by endothelium removal or N(omega)-nitro-L-arginine methyl ester pretreatment, but not by tetraethylammonium or indomethacin pretreatment. In cultured rat aortic endothelial cells, harman (1-100 microM) concentration dependently increased nitric oxide (NO) release, which was dependent on the presence of external Ca(2+). Harman pretreatment (3-30 microM) also concentration dependently inhibited the contractions induced by phenylephrine, 5-hydroxytryptamine (5-HT), and KCl in endothelium-denuded aortic rings in a non-competitive manner. In addition, harman pretreatment reduced both phasic and tonic phases of phenylephrine-induced contractions. Receptor binding assays further indicated that harman (K(i) values around 5-141 microM) interacted with the cardiac alpha(1)-adrenoceptors, brain 5-HT(2) receptors, and cardiac 1, 4-dihydropyridine binding site of L-type Ca(2+) channels. Therefore, the present results suggested that the vasorelaxant effect of harman was attributed to its 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 Ca(2+) channels. The vasorelaxant effect may be involved in the hypotensive effect of harman.

Protein constituent contributes to the hypotensive and vasorelaxant activities of Cordyceps sinensis

Cordyceps sinensis is a herb medicine in China for the treatment of general debility after sickness and for persons of advanced age. In the present study, cordyceps sinensis was extract by phosphate buffer saline (PBS) and dialyzed overnight against PBS using a membrane cut off at 3,500 dalton molecular weight. The resulting macromolecule fraction (defined as CS) was assayed in anesthetized rats for hypotensive effects and in isolated aorta for vasorelaxant effects. Intravenous injection of CS (8,16, 24 and 32 mg/kg, respectively) suppressed significantly the mean arterial pressure (MAP) in a dose-dependent manner. 32 mg/kg of CS induces the maximal hypotensive response with a 58 +/- 4 mm Hg (from 107 +/- 6 to 49 +/- 3 mm Hg) change in MAP and a over 45 min action duration. In aortic rings precontracted with phenylephrine treatment with CS between 0.5 and 500 microg/ml induced dose dependent relaxation. Maximal vasorelaxant response evoked by 150 microg/ml CS was 68.9 +/- 7.3%. Furthermore, CS-induced vasorelaxation is mediated by the endothelium possibly by stimulating the release of the nitric oxide and endothelium-derived hyperpolarizing factor. In conclusion, the present study revealed that presence of a constituent in CS which reduces MAP by relaxing the vascular beds directly. However, the effect may be caused by a single active ingredient or by the combined action of many active agents found in the extract.

Determination of chlorogenic acid in rat blood by microdialysis coupled with microbore liquid chromatography and its application to pharmacokinetic studies

To investigate the pharmacokinetics of unbound chlorogenic acid, a sensitive microbore liquid chromatographic method for the determination of chlorogenic acid in rat blood by microdialysis has been developed. A microdialysis probe was inserted into the jugular vein of male Sprague-Dawley rats, to which chlorogenic acid (20, 40, 60 or 80 mg/kg, i.v.) had been administered. On-line microdialysate was directly injected into a microbore column using a methanol-100 mM sodium dihydrogenphosphate (30:70, v/v, pH 2.5 adjusted with orthophosphoric acid) as the mobile phase and ultraviolet detection at 325 nm. The method is rapid, easily reproduced, selective and sensitive. The limit of detection for chlorogenic acid was 0.01 microg/ml and the limit of quantification was 0.05 microg/ml. The in vivo recovery of the chlorogenic acid of the microdialysis probe, based on a 5 microg/ml standard, was approximately 49-65% (n=6). The disposition of chlorogenic acid at each dose was best fitted to a two-compartment pharmacokinetic model. The area under the concentration curve increased greater than in direct proportion with the dose and terminal disposition become much slower as the dose was increased. The results indicated that the pharmacokinetics of unbound chlorogenic acid in rat blood is non-linear.

Measurement and pharmacokinetics of unbound 20(S)-camptothecin in rat blood and brain by microdialysis coupled to microbore liquid chromatography with fluorescence detection

To characterize the pharmacokinetics of protein-free camptothecin in blood and brain we implanted microdialysis probes into the jugular vein and striatum of rats for unbound drug sampling and determination. Camptothecin (2 or 5 mg/kg, i.v., n=6) was then administered from the femoral vein, and microdialysates were collected from blood and brain of both sites and assayed by a validated microbore scale high-performance liquid chromatographic method. The mobile phase consisted of methanol-100 mM monosodium phosphoric acid (35:65, v/v, pH 2.5) with a flow-rate 0.05 ml/min. The fluorescence response for camptothecin was observed at excitation and emission wavelengths of 360 and 440 nm, respectively. Pharmacokinetic parameters were calculated from the corrected data for dialysate concentrations of camptothecin versus time. The results suggest that the pharmacokinetics of unbound camptothecin in blood and brain can be fitted best to a two- and one-compartment model, respectively. Camptothecin rapidly entered the extracellular fluid of brain striatum at 10 min following camptothecin administration.

Furoquinolines with antiplatelet aggregation activity from leaves of Melicope confusa

Using antiplatelet aggregation as a guide for fractionation, four furoquinoline-type alkaloids, confusameline (1), skimmianine (2), kokusaginine (3), and O-methylconfusameline (4), were isolated from the leaves of Melicope confusa. All compounds showed significant antiplatelet aggregation activity.

Concurrent quantification and pharmacokinetic analysis of cefotaxime in rat blood and brain by microdialysis and microbore liquid chromatography

A simple but effective coupling of microdialysis and microbore liquid chromatograph with UV detection technique was applied to the simultaneous studying of the pharmacokinetics of cefotaxime in both the peripheral compartment and central nervous system. The mobile phase consisted of methanol-100 mM monosodium phosphoric acid (25:75, v/v, pH 5.5) pumped through a C18 microbore column at a flow-rate of 0.05 ml/min. Detection of cefotaxime was set at a UV wavelength of 254 nm. Microdialysis probes were inserted into the jugular vein and striatum of the rat. Following stabilization of microdialysate levels, rats received cefotaxime (20 mg/kg, i.v., n=6) via the femoral vein, and complete concentration versus time profiles for blood and striatum were constructed. The results indicated that cefotaxime rapidly (within 10 min) entered the extracellular fluid of brain striatum following intravenous administration. Noncompartmental pharmacokinetics analysis indicated that the area under the concentration versus time ratio of cefotaxime in rat brain and blood was 6.9%, suggesting appreciable blood-brain barrier penetration. The method was relatively simple, imposed minimal physiological perturbance as it involved no body fluid consumption and sampled in particular protein-unbound drugs, generally believed to be the active fraction.

In vitro and in vivo effects of naringin on cytochrome P450-dependent monooxygenase in mouse liver

In vitro and in vivo effects of naringin on microsomal monooxygenase were studied to evaluate the drug interaction of this flavonoid. In vitro addition of naringin up to 500 microM had no effects on benzo(a)pyrene hydroxylase (AHH) activity of mouse liver microsomes. In contrast, the aglycone naringenin at 300 to 500 microM decreased AHH activity by 50% to 60%. Analysis of Lineweaver-Burk and Dixon plots indicated that naringenin competitively inhibited AHH activity with an estimated Ki of 39 microM. Naringenin at 100 microM also reduced metabolic activation of benzo(a)pyrene to genotoxic products as monitored by umuC gene expression response in Salmonella typhimurium TA1535/pSK1002. In the presence of equimolar naringenin and benzo(a)pyrene, umuC gene expression presented as beta-galactosidase activity was reduced to a level similar to the control value. Administration of a liquid diet containing 10 mg/ml naringin for 7 days caused 38% and 49% decreases of AHH and 7-methoxyresorufin O-demethylase activities, respectively. In contrast, the administration had no effects on cytochrome P450 (P450)-catalyzed oxidations of 7-ethoxyresorufin, 7-ethoxycoumarin, N-nitrosodimethylamine, nifedipine, erythromycin and testosterone. Microsomal P450 and cytochrome b5 contents and NADPH-P450 reductase activity were not affected. Immunoblot analysis using MAb 1-7-1, which immunoreacted with both P450 1A1 and 1A2, revealed that the level of P450 1A2 protein was decreased by 38%. These results demonstrate that naringenin is a potent inhibitor of AHH activity in vitro and naringin reduces the P450 1A2 protein level in vivo. These effects may indicate a chemopreventive role of naringin against protoxicants activated by P450 1A2.