Visual detection of specific, native interactions between soluble and microbead-tethered alpha-helices from membrane proteins

Using peptides tethered to polymer microbeads, we have developed a technique for measuring the interactions between the transmembrane alpha-helices of membrane proteins and for screening combinatorial libraries of peptides for members that interact with specific helices from membrane proteins. The method was developed using the well-characterized homodimerization sequence of the membrane-spanning alpha-helix from the erythrocyte membrane protein glycophorin A (GPA). As a control, we also tested a variant with a dimer-disrupting alteration of a critical glycine residue to leucine. To test for detectable, native interactions between detergent-solubilized and microbead-tethered alpha-helices, we incubated fluorescent dye-labeled GPA analogues in sodium dodecyl sulfate solution with microbeads that contained covalently attached GPA analogues. When the dye-labeled peptide in solution and the bead-tethered peptide both contained the native glycophorin A sequence, the microbeads readily accumulated the dye through lateral peptide-peptide interactions and were visibly fluorescent under UV light. When either the peptide in solution or the peptide attached to the beads contained the glycine to leucine change, the beads did not accumulate any dye. The usefulness of this method for screening tethered peptide libraries was tested by incubating dye-labeled, native sequence peptides in detergent solution with a few native sequence beads plus an excess of beads containing the variant glycine to leucine sequence. When the dye-labeled peptide in solution was present at a concentration of > or =2 microM, the few native sequence beads were visually distinguishable from the others because of their bright fluorescence. Using this model system, we have shown that it is possible to visually detect specific, native interactions between alpha-helices from membrane proteins using peptides tethered to polymer microbeads. It will thus be possible to use this method to measure the specific lateral interactions that drive the folding and organization of membrane proteins and to screen combinatorial libraries of peptides for members that interact with them.

Cytosolic-free calcium in smooth-muscle and endothelial cells in an intact arterial wall from rat mesenteric artery in vitro

The regulation of cytosolic-free calcium concentration of smooth-muscle and endothelial cells was mainly studied on cultured cells where the cross talk between these two coupled cell types is lost. In the present study, the cytosolic-free calcium concentration in the endothelial and the smooth-muscle cells was examined in an intact arterial wall in vitro. Strips of the main branch of rat mesenteric artery were used. Cytosolic-free calcium concentration [Ca2+]i was estimated by determining the fluorescence ratio of the two calcium probes, Fluo-4 and Fura red. The emitted fluorescence of both probes was measured with a confocal microscope. We showed that potassium and phenylephrine, which increase the cytosolic -free calcium concentration of the smooth-muscle cells, also indirectly influence the calcium concentration in the endothelial cells. By simultaneously determining [Ca2+]i in the endothelial and the smooth-muscle cells of an arterial strip, we observed that when calcium increases in the endothelial cells in response to acetylcholine, it slightly decreases in the smooth-muscle cells. We conclude that the regulation of [Ca2+]i in the arterial endothelial cell, depends according to the stimuli either upon the endothelial cells themselves, or upon the coupled smooth-muscle cells.

Serotonin projection patterns to the cochlear nucleus

The cochlear nucleus is well known as an obligatory relay center for primary auditory nerve fibers. Perhaps not so well known is the neural input to the cochlear nucleus from cells containing serotonin that reside near the midline in the midbrain raphe region. Although the specific locations of the main, if not sole, sources of serotonin within the dorsal cochlear nucleus subdivision are known to be the dorsal and median raphe nuclei, sources of serotonin located within other cochlear nucleus subdivisions are not currently known. Anterograde tract tracing was used to label fibers originating from the dorsal and median raphe nuclei while fluorescence immunohistochemistry was used to simultaneously label specific serotonin fibers in cat. Biotinylated dextran amine was injected into the dorsal and median raphe nuclei and was visualized with Texas Red, while serotonin was visualized with fluorescein. Thus, double-labeled fibers were unequivocally identified as serotoninergic and originating from one of the labeled neurons within the dorsal and median raphe nuclei. Double-labeled fiber segments, typically of fine caliber with oval varicosities, were observed in many areas of the cochlear nucleus. They were found in the molecular layer of the dorsal cochlear nucleus, in the small cell cap region, and in the granule cell and external regions of the cochlear nuclei, bilaterally, of all cats. However, the density of these double-labeled fiber segments varied considerably depending upon the exact region in which they were found. Fiber segments were most dense in the dorsal cochlear nucleus (especially in the molecular layer) and the large spherical cell area of the anteroventral cochlear nucleus; they were moderately dense in the small cell cap region; and fiber segments were least dense in the octopus and multipolar cell regions of the posteroventral cochlear nucleus. Because of the presence of labeled fiber segments in subdivisions of the cochlear nucleus other than the dorsal cochlear nucleus, we concluded that the serotoninergic projection pattern to the cochlear nucleus is divergent and non-specific. Double-labeled fiber segments were also present, but sparse, in the superior olive, localized mainly in periolivary regions; this indicated that the divergence of dorsal and median raphe neurons that extends throughout regions of the cochlear nucleus also extended well beyond the cochlear nucleus to include at least the superior olivary complex as well.

Determination of the covalent adducts of the novel anti-cancer agent 5,6-dimethylxanthenone-4-acetic acid in biological samples by high-performance liquid chromatography

The reversed-phase HPLC methods were developed to determinate the covalently bound protein adducts of the novel anti-cancer drug 5,6-dimethylxanthenone-4-acetic acid (DMXAA) via its glucuronides after releasing aglycone by alkaline hydrolysis in human plasma and human serum albumin (HSA). An aliquot of 75 microl of the mixture was injected onto a Spherex C18 column (150x4.6 mm; 5 microm) at a flow-rate of 2.5 ml/min. The mobile phase comprising of acetonitrile:10 mM ammonium acetate buffer (24:76, v/v, pH 5.8) was used in an isocratic condition, and DMXAA was detected by fluorescence. The method was validated with respect to recovery, selectivity, linearity, precision, and accuracy. Calibration curves for DMXAA were constructed in the concentration range of 0.5-40 microM in washed blank human plasma or HSA prior to alkaline hydrolysis. The difference between the theoretical and calculated concentration and the relative standard deviation were less than 10% at all quality control (QC) concentrations. The limit of detection for the covalent adduct in human plasma or HSA is 0.20 microM. The methods presented good accuracy, precision and sensitivity for use in the preclinical and clinical studies.

Signal transduction in red bloodcells of the lizards Ameiva ameiva and Tupinambis merianae (Squamata, Teiidae)

The fluorescent calcium probe, Fluo-3, AM was used to measure the intracellular calcium concentration in red blood cells (RBCs) of the teiid lizards Ameiva ameiva and Tupinambis merianae. The cytosolic [Ca2+] is maintained around 20 nM and the cells contain membrane-bound Ca2+ pools. One pool appears to be identifiable with the endoplasmic reticulum (ER) inasmuch as addition of the sarco-endoplasmic reticulum Ca2+ ATPase, SERCA, inhibitor thapsigargin induces an increase in cytosolic [Ca2+ both in the presence and in the absence of extracellular Ca2+. In addition to the ER, an acidic compartment appears to be involved in Ca2+ storage, as collapse of intracellular pHgradients by monensin, a Na+ -H+ exchanger, and nigericin, a K+ -H+ exchanger, induce the release of Ca2+ from internal pools. A vacuolar H+ pump, sensitive to NBD-Cl and bafilomycin appears to be necessary to load the acidic Ca2+ pools. Finally, the purinergic agonist ATP triggers a rapid and transient increase of [Ca2+]c in the cells from both lizard species, mostly by mobilization of the cation from internal stores.

Polyphenol Constituents from Salacia Species: Quantitative Analysis of Mangiferin with α-Glucosidase and Aldose Reductase Inhibitory Activities

Mangiferin, three catechins, and two catechin dimers were isolated from the roots of Salacia reticulata (SRE), and examined their inhibitory activities against several carbohydrate metabolize enzymes (sucrase, maltase, isomaltase, alpha-amylase, and aldose reductase). Among them, mangiferin was found to inhibit sucrase, isomaltase, and aldose reductase from rat with IC50 values of 87, 216 and 1.4 micrograms/ml, respectively. The inhibitory activities of mangiferin are competitive for sucrase and isomaltase with inhibitor constant (Ki) 55 micrograms/ml and 70 micrograms/ml, respectively. In order to determine the mangiferin contents in the water extracts from the roots of S. reticulata, a quantitative analytical method by means of HPLC was developed and the mangiferin contents in SRE were determined to be in the range of 0.9-2.3% by the application of this method. A high linear correlation (r = 0.934) was observed between the mangiferin contents and the sucrase inhibitory activity. In addition, this analytical procedure of mangiferin was found to be applicable for other Salacia species (S. oblonga, S. chinensis, and S. prinoides). Thus, the quantitative HPLC analysis of mangiferin was supposed to be suitable for the quality control of Salacia species and its products.

Adenosine A1 receptor activation reduces reactive oxygen species and attenuates stunning in ventricular myocytes

Reactive oxygen species (ROS) formation following brief periods of ischemia or hypoxia is thought to be the underlying cause of myocardial stunning. Adenosine A1 receptor activation prior to ischemia/hypoxia attenuates stunning, although the mechanism for this effect remains unknown. Isolated rat ventricular myocytes loaded with the ROS-sensitive indicator dichlorofluorescin were subjected to 30 min glucose-free hypoxia followed by reoxygenation. Intracellular ROS increased approximately 175% (from pre-hypoxic levels) during reoxygenation while cell shortening decreased approximately 50%. In myocytes pretreated with the adenosine A1 agonist 2-chloro-N(6)-cyclopentyladenosine (CCPA), reoxygenation-induced ROS formation was attenuated by 40% and stunning was attenuated by 50% (compared to untreated myocytes). The mitochondrial K(ATP) channel opener diazoxide mimicked the effects of CCPA. Pretreatment with the mitochondrial K(ATP) channel blocker 5-hydroxydecanoate, or the non-selective K(ATP) channel blocker glibenclamide, blocked the effects of CCPA. These results suggest that adenosine A1 receptor activation attenuates stunning by reducing ROS formation. These effects of A1 receptor activation appear to be dependent on the opening of K(ATP) channels.

Method for determination of xanthene dyes in guava fruits and its application in a field dissipation study

Xanthene dyes, i.e., phloxine B and uranine or phloxine B alone, are phototoxic to tephritid fruit flies infesting guava fruits. An analytical method was developed for determination of residues of these dyes used in bait solutions for suppression of the tephritid fruit fly population in guava fruits. The procedure involved solvent extraction, anion-exchange cleanup, and determination by liquid chromatography or capillary zone electrophoresis. The dyes were extracted from 50 g guava fruit at 45 degrees degrees with 400 mL methanol-acetonitrile (1 + 1) and 5 g magnesium oxide added as an alkaline and clarifying agent. The guava extract was adjusted to pH 8.5 and subjected to an amino column cleanup. Average recoveries of xanthene dyes added to guava purees ranged from 77 to 99% for phloxine B and from 79 to 102% for uranine at spiking levels of 0.05-1.00 microg/g. The method was applied to the determination of phloxine B residues in guava fruits collected from a dye-sprayed orchard. After phloxine B was applied at a rate of 62.5 g/ha for 14 weekly sprayings, it was found on guava fruits at an average concentration of 111 +/- 18 ng/g 4 h after the llth spraying. The concentration of phloxine B was 426 +/- 94 ng/g in selected fruits with high deposits of the dye 4 h after spraying. Average concentrations of phloxine B 5 days after the 7th and 14th sprayings were 29 +/- 7 and 19 +/- 8 ng/g, respectively.

A laser scanning confocal microscopy method. Simultaneous detection of intracellular Ca2+ and apoptosis using Fluo-3 and Hoechst 33342

OBJECTIVE

To develop a simple and direct method to simultaneously determine apoptotic cells from a treated population of cells and detect the changes of intracellular Ca2+ in these apoptotic cells, in particular single ones, by confocal microscopy.

STUDY DESIGN

MGC-803 cells treated with As2O3 were used as the double-staining cell model with Hoechst 33342 as a DNA probe and Fluo-3AM as a Ca2+ indicator. MGC-803 cell apoptosis induced by As2O3 was first demonstrated by DNA ladder in gel electrophoresis. Based on the difference in DNA stainability with Hoechst 33342 and corresponding fluorescence intensity between live and apoptotic cells, apoptotic cells and the changes in intracellular Ca2+ were detected at the same time by confocal microscopy. No necrotic cells in the group treated with As2O3 were found by the trypan blue exclusion test.

RESULTS

The results from confocal microscope detection showed that intact and apoptotic cells were successfully recognized and the changes of intracellular Ca2+ in apoptotic and intact cells were simultaneously detected in the same sample.

CONCLUSION

We provided a useful method to exactly detect changes in intracellular Ca2+ in apoptotic cells, especially in single ones, by confocal microscopy and to exclude the artifact effect of necrotic and intact cells.

Xanthones and triterpenoids from the bark of Garcinia vilersiana

The hexane extract of the bark of Garcinia vilersiana from Vietnam contained four triterpenoids (olean-12-ene-3beta,11alpha-diol, lupeol, beta-amyrin and oleanolic acid), and six xanthones (globuxanthone, subelliptenone H, subelliptenone B, 12b-hydroxy-des-D-garcigerrin A, 1-O-methylglobuxanthone and symphoxanthone). The structure of 1-O-methylglobuxanthone, the only novel compound, was determined using 1D and 2D NMR techniques and by correlation with globuxanthone.

GABA- and glutamate-mediated network activity in the hippocampus of neonatal and juvenile rats revealed by fast calcium imaging

In the rat hippocampus, during the first postnatal week, network activity is characterized by GABA-driven giant depolarizing potentials (GDPs) associated with calcium signals that are readily blocked when the GABAA antagonist bicuculline is applied to the bath. Towards the end of the first postnatal week, in concomitance with the shift of GABA responses from the depolarizing to the hyperpolarizing direction, functional glutamatergic connections start appearing. At this developmental stage, application of bicuculline blocks GABAA-mediated inhibition and induces the appearance of interictal epileptiform discharges. In the present experiments, we have used a high spatio-temporal resolution imaging system to compare, on a time scale of tens of ms, the onset and propagation of fast calcium transients generated within a GABAergic or glutamatergic network. We found that, during the first postnatal week, calcium signals associated to evoked GDPs arise from the activation of a local circuitry of neurons spanning the stratum radiatum and the pyramidal layer. Similar activation patterns were elicited by focal application of GABA in the presence of kynurenic acid, a broad spectrum ionotropic glutamatergic antagonist, and were blocked by bicuculline. During the second postnatal week, in the presence of bicuculline, calcium signals associated with interictal discharges evoked by stimulation of glutamatergic fibres propagated along the well-defined three-synaptic pathway from the dentate gyrus to the CA1 hippocampal area.

Errors caused by combination of Di-4 ANEPPS and Fluo3/4 for simultaneous measurements of transmembrane potentials and intracellular calcium

Intracellular calcium concentration and transmembrane potentials are two important measurements used to study the mechanisms of cardiac activity. Fluorescent dyes have been used to measure these separately but not simultaneously in cardiac tissue. Fluo-3 and Fluo-4 (a recently improved version of Fluo-3) have been used to measure changes in intracellular calcium concentration and Di-4 ANEPPS has been used to measure transmembrane potentials. This paper addresses the feasibility of using these fluorescent dyes together in order to measure transmembrane potentials and intracellular calcium concentration simultaneously. For the dyes to be used simultaneously, their respective fluorescence spectra must be sufficiently separated in wavelength in order to allow them to be separated by optical filters or spectrographs. An apparatus was constructed to measure the dyes' spectra in a fluorescence imaging chamber as well as in an isolated perfused rabbit heart. The measured spectra were mathematically modeled in order to assess the spectral overlap error under different conditions. Error graphs were constructed which may help researchers select optical filters and dye concentrations that will result in an acceptable error.

Pregnenolone sulfate exacerbates NMDA-induced death of hippocampal neurons

Excessive stimulation of the N-methyl-d-aspartate (NMDA)-type glutamate receptor has been implicated in the neuronal death resulting from focal hypoxia-ischemia. Certain neurosteroids, steroids synthesized de novo in the central nervous system (CNS), have been shown to modulate the action of neurotransmitters at their cellular receptors. Pregnenolone sulfate (PS) is an abundant neurosteroid that enhances the current evoked by NMDA. Using the Ca2+-sensitive fluorescent dye, Fluo-3, AM, and a trypan blue exclusion assay, we evaluated the ability of PS to modulate NMDA-induced changes in intracellular free calcium concentration ([Ca2+]i) and neuronal death in primary cultures of rat hippocampal neurons. The results demonstrate that PS potentiates NMDA-induced increases in [Ca2+]i by 150%. Further, PS exacerbates the MK-801-sensitive neuronal death produced by acute (PS EC50=37 microM) or chronic NMDA exposure, reducing the EC50 of NMDA from 13 to 4 microM under chronic exposure conditions, whereas pregnenolone is ineffective. Our results show that PS, or related sulfated neurosteroids, may play a role in the onset of excitotoxic neuronal death in vivo.

Aminoglycoside antibiotics traffic to the Golgi complex in LLC-PK1 cells

Aminoglycoside antibiotics are known to be internalized via endocytosis and have been associated with subcellular organelle dysfunction; however, the route of intracellular trafficking and their distribution remain largely unknown. To address these questions, a Texas Red conjugate of gentamicin (TRG) was synthesized for dual-labeling experiments with the endoplasmic reticulum, Golgi, and lysosomal markers DiOC6-3, C6-NBD-ceramide, and fluorescent dextrans, respectively. Confocal images were overlaid to determine areas of colocalization. Initial characterization studies of the fluorescent gentamicin analogue revealed that both internalization and accumulation were inhibited by excess unlabeled gentamicin. Furthermore, the fluorescent gentamicin label was colocalized with unlabeled gentamicin, using immunologic techniques. LLC-PK1 cells were exposed to the fluorescent gentamicin in media containing 1 mg/ml labeled gentamicin for 8 h and then either fixed or chased with gentamicin-free media for an additional 16 or 40 h (24 to 48 h total). Studies with fluorescent dextrans revealed rapid intracellular colocalization within the endosomal and lysosomal systems. Neither endoplasmic reticulum nor mitochondrial colocalization could be detected. However, Golgi colocalization was revealed using both confocal and electron microscopic techniques at 8 h of TRG incubation, and continued to be present for an additional 40 h. Protein synthetic rates were quantified and revealed decreased synthesis at the 24-h chase mark. These results suggest that TRG can serve as a fluorescent tracer for aminoglycoside trafficking within cells. The fluorescent marker remained associated with vesicular structures at all times and colocalized with the Golgi apparatus. It is postulated that this early association of gentamicin with the Golgi complex may be an avenue for delivery of aminoglycosides to other intracellular compartments.

Detection of phosphatidylinositol glycan class A gene transcripts by RT in situ PCR hybridization. A comparative study using fluorescein, Texas Red, and digoxigenin-11 dUTP for color detection

Gene-specific probes labeled with fluorescein, Texas Red, and digoxigenin-11 dUTP (DIG) were used for RT in situ PCR hybridization to detect PIG-A gene (phosphatidylinositol glycan class A) transcripts. The PIG-A gene is responsible for biosynthesis of the glycosylphosphatidyl-inositol (GPI) anchor. Lack of GPI anchor expression due to mutations can cause an acquired clonal hematologic disorder called paroxysmal nocturnal hemoglobinuria (PNH). In this RT in situ PCR study, two types of labeling methods, a direct method (using fluorescein and Texas Red) and an indirect method (using DIG-11 dUTP) were compared. Both were successfully applied to detect and localize the PIG-A gene transcripts within single cells of the cell lines AA2, H9, and JY. Furthermore, similar results for sensitivity and reproducibility were obtained. Advantages and disadvantages of the different labeling techniques are discussed. In addition, peripheral blood mononuclear cells from PNH patients were also included in this study.

[Determination of mangiferin in qingqiliangying injection by reversed-phase HPLC]

A reversed-phase HPLC method has been established for the determination of mangiferin in Qingqiliangying Injection. The mangiferin was separated on a Nova-pak C18 column (150 mm x 3.9 mm) and detected at 258 nm, using methanol-tetrahydrofuran-0.85% H3PO4 aqueous solution (500:80:15) as the mobile phase. The average recovery of mangiferin was 100.9%. The method is simple, rapid, and well reproducible, and thus very reliable for the quality control of Qingqiliangying Injection.

[D-Pen2,5]enkephalin and glutamate regulate the expression of delta-opioid receptors in rat cortical astrocytes

Recent work from our and other laboratories have shown that glial cells in culture express opioid receptors. In the present study we have analyzed the regulation of delta-opioid receptor mRNA and the regulation of delta-opioid receptor activated astroglial Ca2+ responses in primary cultures from the rat cerebral cortex. Astroglial cultures were incubated with glutamate (Glu) or [D-Pen2,5]enkephalin (DPDPE) for 48 h, and delta-opioid receptor mRNA levels were analyzed using a solution hybridization RNase protection assay. Our results suggest that incubation in Glu or DPDPE upregulates the abundance of delta-opioid receptor mRNA in a dose dependent way. Glu incubated cells showed a maximum upregulation at the highest agonist concentration used (10[-5] M), whereas DPDPE was most effective at low concentrations (l0[-9] M). Furthermore, corresponding Ca2+ imaging experiments showed that incubation in Glu or DPDPE upregulated the responding frequency of delta-opioid receptor activated glial calcium fluxes from a control value of 5% to 14% and 17% responding cells, respectively.

[Effect of processing on chemical composition and medical activity of rhizoma Anemarrhenae]

A comparative study was conducted on the chemical composition and medical activity of different kinds of processed drug of Rhizoma Anemarrhenae. It was found that the content of effective components of zhimu was affected obviously by processing: the rhizome should not be barked when used as drug. It was also observed that different kind of processed drug should be used in line with different particular circumstance.

Rapid coupling of calcium release to depolarization in Limulus polyphemus ventral photoreceptors as revealed by microphotolysis and confocal microscopy

Microphotolysis and confocal microscopy were used to investigate the timing of calcium release and of the electrical response in Limulus polyphemus ventral photoreceptors. The fluorescent dyes Fluo-3 and Calcium Green-5N were used to monitor local Ca2+ elevations. Photolysis of caged inositol trisphosphate (InsP3) close to the plasma membrane of the light-sensitive rhabdomeral (R-) lobe resulted in Ca2+ elevation within 10-20 msec, 20-45 msec before the physiological response to light normally would be detected. Inward ionic current flow and depolarization followed InsP3-induced calcium release within 2.5 +/- 3.3 msec. Voltage-clamping the cells and removal of extracellular Ca2+ did not affect the timing of the Ca2+ elevation that followed the photolysis of caged InsP3 or its relationship to the electrical response. In contrast to the physiological response to light, which only released calcium within the R-lobe, photolysis of InsP3 elevated Cai in both lobes, although with much greater effect in the R-lobe, as compared with the bulk of the A-lobe, suggesting the presence of InsP3-sensitive calcium stores in both lobes. Photolysis of caged calcium [o-nitrophenyl EGTA (NPE)] at the edge of the R-lobe activated an inward ionic current within 1.8 +/- 0.7 msec. This NPE-induced current reversed at a membrane potential of 10 +/- 6 mV in the range typical of that of the light-activated current under physiological conditions. Calcium release, therefore, activates an inward current rapidly enough to contribute to the electrical response to light.

Loading and localization of Fluo-3 and Fluo-3/AM calcium indicators in sinapis alba root tissue

Stimulus-induced changes in free cytosolic Ca2+ in different types of plant cells have been monitored with the aid of fluorescent calcium indicator dyes. However, there is no simple and convenient method for introducing these dyes into the plant cell cytoplasm. This paper reports tests of different procedures for loading either free fluorescent dyes or their acetoxymethyl esters (Fluo-3 and Fluo-3/AM, respectively) into Sinapis alba root tissue. Loading of Fluo-3 was pH and temperature dependent. Moreover, in the presence of beta-escin (saponin) in the loading medium very high fluorescent signals in root tissues were observed. The highest signals were recorded when tissue was loaded in a medium containing 0.1% beta-escin, at pH 5.0 and 30 degrees C. Only very weak fluorescence signals were found in mustard roots loaded with Fluo-3/AM. Acidity and temperature of the medium had no significant effect on the process. However, addition of eserine, a cholinesterase inhibitor led to a dramatic increase in fluorescence in the root cells. On the basis of these observations rapid and efficient methods of loading both Fluo-3 and Fluo-3/AM into mustard root tissues are proposed.

Determination of gentiopicroside, mangiferin, palmatine, berberine, baicalin, wogonin and glycyrrhizin in the traditional Chinese medicinal preparation sann-joong-kuey-jian-tang by high-performance liquid chromatography

High-performance liquid chromatography was employed to determine the contents of several marker substances such as gentiopicroside, mangiferin, palmatine, berberine, baicalin, wogonin and glycyrrhizin in Sann-Joong-Kuey-Jian-Tang. The separation was performed on a Cosmosil 5C18-AR column by gradient elution with 0.03% (v/v) phosphoric acid-acetonitrile (0 min, 90:10; 10 min, 87:13; 17-27 min, 77:23; 40 min, 62:38; 50 min, 55:45) as the mobile phase at a flow-rate of 1.0 ml/min, with detection at 254 nm. n-Propylparaben was used as the internal standard and seven regression equations revealed linear relationships between the peak-area ratios (marker substances/internal standard) and concentrations. The repeatability and reproducibility (relative standard deviation) of the method were in the ranges 0.02-1.78% and 1.44-4.95%, respectively.

[Botanical survey and quality evaluation of Chinese drug shiwei (folium Pyrrosiae)]

This paper deals with a botanical survey and identification of the Chinese drug Shiwei (Folium Pyrrosiae) on the basis of three most widely used species included in the 1985 edition of Chinese Pharmacopoeia, six species used in some districts of China, and two adulterant species. Three active constituents in seven species of Folium Pyrrosiae (mangiferin, isomangiferin and chlorogenic acid) have been determined.

Effects of a putative prostaglandin E2 antagonist, AH6809, on chondrogenesis in serum-free cultures of chick limb mesenchyme

In the present study, we have examined the effects of a putative antagonist of prostaglandin E2 (PGE2), AH6809, on chondrogenesis in serum-free cultures of mesenchyme from distal tips of stage 25 chick limb buds in order to test the hypothesis that endogenous PGE2, through receptor-linked adenylate cyclase (AC), initiates differentiation of cartilage in limb mesenchyme. Daily addition of 10(-4) M concentrations of AH6809 produced marked inhibition of chondrogenesis over a 5-day period of cell culture as evaluated by Alcian green binding to cartilage matrix components. Inhibition of chondrogenesis by this compound was further shown to be reversible and treatment of cells with the antagonist limited to periods when chondrocytes had differentiated and were actively secreting cartilage-specific matrix components had little effect. Preincubation of control cells in 10(-4) M concentrations of AH6809 inhibited PGE2-induced activation of AC by greater than 80% without significant (P greater than .05) inhibition of basal activity by the antagonist. Responses to parathyroid hormone, which increased AC activity by 7-fold, and forskolin which increased AC activity by 23-fold in control cells, were also uninhibited by preincubation in AH6809. The results demonstrate that blockade of PGE2-AC linked receptors in prechondrogenic limb mesenchyme inhibits chondrogenesis supporting the hypothesis that endogenous PGE2 concentrations in undifferentiated limb mesenchyme play an initiating role in the differentiation of cartilage.

Analysis of xanthene dyes by reversed-phase high-performance liquid chromatography on a polymeric column followed by characterization with a diode array detector

A high-performance liquid chromatographic method on a polymeric column was developed for the analysis of xanthene dyes. The rigid polystyrene-divinylbenzene column was connected to a photodiode array detector to verify the identity and the purity of the dyes. For eosin Y a within-day precision of 1-2% was obtained, and on a day-to-day basis the coefficient of variation was 4.2%. The purity of commercial xanthene dyes was investigated, and the results show the divergence between the actual dye contents and the dye contents indicated on the label.