Solid phase microextraction as a powerful alternative for screening of secondary metabolites in actinomycetes

Actinobacteria are one of the most promising producers of medically and industrially relevant secondary metabolites. However, screening of such compounds in actinobacteria growth demands simple, fast, and efficient extraction procedures that enable detection and precise quantification of biologically active compounds. In this regard, solid phase microextraction (SPME) emerges as an ideal extraction technique for screening of secondary metabolites in bacteria culture due to its non-exhaustive, minimally invasive, and non-destructive nature: its integrated sample preparation workflow; balanced coverage feature; metabolism quenching capabilities; and superior cleanup, as well as its versatility in configuration, which enables automation and high throughput applications. The current work provides a comparison of micro-scale and direct immersion SPME (DI-SPME) for screening of secondary metabolites, describes the optimization of the developed DI-SPME method, and introduces the developed technique for mapping of target secondary metabolites as well as its direct coupling to mass spectrometry for such applications. The optimized DI-SPME method provided higher amounts of extracted ions and intensity signals, yielding superior extraction and desorption efficiency as compared with micro-scale extraction. Studied compounds presented stability on the coating for 24 h at room temperature. The DI-SPME mapping approach revealed that lysolipin I and the lienomycin analog are distributed along the center and edges of the colony, respectively. Direct coupling of SPME to MS provided a similar ions profile as SPME-LC-MS while enabling a significant decrease in analysis time, demonstrating its suitability for such applications. DI-SPME is herein presented as an alternative to micro-scale extraction for screening of secondary metabolites in actinobacteria solid medium, as well as a feasible alternative to DESI-IMS for mapping of biologic radial distribution of secondary metabolites and cell life cycle studies. Lastly, the direct coupling of DI-SPME to MS is presented as a fast, powerful technique for high throughput analysis of secondary metabolites in this medium.

Flow Cytometry and Fluorescence Microscopy as Tools for Structural and Functional Analysis of Vacuoles Isolated from Yeast and Plant Cells

A series of optimized protocols to isolate vacuoles from both yeast and plant cells, and to characterize the purified organelles at a functional and structural level, are described. For this purpose, we took advantage of the combined use of cell fractionation techniques with different fluorescence-based approaches namely flow cytometry, fluorescence microscopy and spectrofluorimetry. These protocols altogether constitute valuable tools for the study of vacuole structure and function, as well as for the high-throughput screening of drug libraries to identify new molecules that target the vacuole.

A far-red fluorescent probe for flow cytometry and image-based functional studies of xenobiotic sequestering macrophages

Clofazimine (CFZ) is an optically active, red-colored chemotherapeutic agent that is FDA approved for the treatment of leprosy and is on the World Health Organization's list of essential medications. Interestingly, CFZ massively accumulates in macrophages where it forms crystal-like drug inclusions (CLDIs) after oral administration of the drug in animals and humans. The analysis of the fluorescence spectra of CLDIs formed by resident tissue macrophages revealed that CFZ, when accumulated as CLDIs, undergoes a red shift in fluorescence excitation (from Ex: 540-570 to 560-600 nm) and emission (Em: 560-580 to 640-700 nm) signal relative to the soluble and free-base crystal forms of CFZ. Using epifluorescence microscopy, CLDI(+) cells could be identified, relative to CLDI(-) cells, based on a >3-fold increment in mean fluorescence signal at excitation 640 nm and emission at 670 nm. Similarly, CLDI(+) cells could be identified by flow cytometry, based on a >100-fold increment in mean fluorescence signal using excitation lasers at 640 nm and emission detectors >600 nm. CLDI's fluorescence excitation and emission was orthogonal to that of cell viability dyes such as propidium iodide and 4,6-diamidino-2-phenylindole dihydrochloride (DAPI), cellular staining dyes such as Hoechst 33342 (nucleus) and FM 1-43 (plasma membrane), as well as many other fluorescently tagged antibodies used for immunophenotyping analyses. In vivo, >85% of CLDI(+) cells in the peritoneal exudate were F4/80(+) macrophages and >97% of CLDI(+) cells in the alveolar exudate were CD11c(+). Most importantly, the viability of cells was minimally affected by the presence of CLDIs. Accordingly, these results establish that CFZ fluorescence in CLDIs is suitable for quantitative flow cytometric phenotyping analysis and functional studies of xenobiotic sequestering macrophages.

Direct measurements of SR free Ca reveal the mechanism underlying the transient effects of RyR potentiation under physiological conditions

AIMS

Most of the calcium that activates contraction is released from the sarcoplasmic reticulum (SR) through the ryanodine receptor (RyR). It is controversial whether activators of the RyR produce a maintained increase in the amplitude of the systolic Ca transient. We therefore aimed to examine the effects of activation of the RyR in large animals under conditions designed to be as physiological as possible while simultaneously measuring SR and cytoplasmic Ca.

METHODS AND RESULTS

Experiments were performed on ventricular myocytes from canine and ovine hearts. Cytoplasmic Ca was measured with fluo-3 and SR Ca with mag-fura-2. Application of caffeine resulted in a brief increase in the amplitude of the systolic Ca transient accompanied by an increase of action potential duration. These effects disappeared with a rate constant of ∼3 s(-1). Similar effects were seen in cells taken from sheep in which heart failure had been induced by rapid pacing. The decrease of Ca transient amplitude was accompanied by a decrease of SR Ca content. During this phase, the maximum (end-diastolic) SR Ca content fell while the minimum systolic increased.

CONCLUSIONS

This study shows that, under conditions designed to be as physiological as possible, potentiation of RyR opening has no maintained effect on the systolic Ca transient. This result makes it unlikely that potentiation of the RyR has a maintained role in positive inotropy.

Rapid Susceptibility Test for Mycobacterium tuberculosis to Isoniazid and Rifampin with Resazurin Method in Screw-Cap Tubes

Multi-drug resistant (MDR) Mycobacterium tuberculosis is still a serious public health problem all over the world. MDR tuberculosis (MDR-TB) caused by these strains has emerged within the last decade and rapid detection is critical for the effective treatment of patients. Recently, a resazurin microtiter assay plate for detecting MDR strains was developed. In this study, it was adapted to screw-cap tubes and the activity of isoniazid (INH) and rifampin (RIF) to 50 M. tuberculosis clinical isolates was tested by this method for the first time. Results were compared with the radiometric reference method for the susceptibility testing of M. tuberculosis complex. The results of both methods were in 100% and 96% agreement for RIF and INH, respectively. Specificity, sensitivity, positive predictive value and negative predictive value were 91.7%, 100%, 92.8% and 100% for INH, respectively. All of these values were 100% for RIF. Susceptibility testing results were obtained on the 8th day of incubation for 42 isolates and on the 9th day for the other eight strains. Our results indicate that this method is suitable for the early determination of INH and RIF resistance in developing countries because it is inexpensive, rapid and easy to perform.

[Simultaneous determination of paeoniflorin, ferulic acid, prim-O-glucosylcimifugin and 4'-O-beta-glucopyranosyl-5-O-methylvisamminol in zhengtian pills by HPLC]

To simultaneously determine paeoniflorin, ferulic acid, prim-O-glucosylcimifugin and 4'-O-beta-glucopyranosyl-5-O-methylvisamminol in Zhengtian pills. In the test, Insertil ODS-C18 column (4.6 mm x 250 mm, 5 microm) was adopted, with acetonitrile-0.05% phosphoric acid solution as the mobile phase for gradient elution. The flow rate was 1.0 mL x min(-1), the column temperature was 30 degrees C and the detection wavelength was 230 nm. According to the results of the test, paeoniflorin, ferulic acid, prim-O-glucosylcimifugin and 4'-O-beta-glucopyranosyl-5-O-methylvisamminol showed good linear relations between peak areas and sample sizes in 11.37-170.5, 2.188-32.82, 2.896-43.44, and 3.000-45.00 mg x L(-1) (r = 0.999 9, 0.999 9, 1.000 0, 1.000 0), respectively. The average recoveries (n = 6) were 102.3% (RSD 1.2%), 99.71% (RSD 1.9%), 101.2% (RSD 1.2%), and 99.40% (RSD 2.4%), respectively. The above four components were determined in five batches of samples by using the established method, with satisfactory results. The method was so simple, accurate and highly reproducible that it could be used for quality control of the four components in Zhengtian pills.

tmie Is required for gentamicin uptake by the hair cells of mice

The circling (cir/cir) mouse is a spontaneous model of deafness due to deletion of a 40-kb genomic region that includes the transmembrane inner ear (tmie) gene. In addition to being deaf, cir/cir mice exhibit abnormal behaviors including circling and hyperactivity. Here we investigated differences between 3-d-old (that is, before hair-cell degeneration) cir/cir and phenotypically normal (+/cir) mice and the reason underlying the degeneration of the inner ear structure of cir/cir mice. To this end, we used gentamicin, gentamicin-Texas red conjugate, and FM1-43 to investigate mechanotransducer channel activity in the hair cells of cir/cir mice; these compounds are presumed to enter hair cells through the mechanotransducer channel. Although the structure of the inner ear of +/cir mice was equivalent to that of cir/cir mice, the hair cells of cir/cir mice (unlike +/cir) did not take up gentamicin, gentamicin-Texas red conjugate, or FM1-43. These findings suggest that hair cells in cir/cir mice demonstrate abnormal maturation and mechanotransduction. In addition, our current results indicate that tmie is required for maturation and maintenance of hair cells.

DNA concentration modulation on supported lipid bilayers switched by surface acoustic waves

Spatially addressable arrays of molecules embedded in or anchored to supported lipid bilayers are important for on-chip screening and binding assays; however, methods to sort or accumulate components in a fluid membrane on demand are still limited. Here we apply in-plane surface acoustic shear waves (SAWs) to laterally accumulate double-stranded DNA segments electrostatically bound to a cationic supported lipid bilayer. The fluorescently labeled DNA segments are found to segregate into stripe patterns with a spatial frequency corresponding to the periodicity of the standing SAW wave (~10 μm). The DNA molecules are accumulated 10-fold in the regions of SAW antinodes. The superposition of two orthogonal sets of SAW sources creates checkerboard like arrays of DNA demonstrating the potential to generate arrayed fields dynamically. The pattern relaxation time of 0.58 s, which is independent of the segment length, indicates a sorting and relaxation mechanism dominated by lipid diffusion rather than DNA self-diffusion.

RGDS-fuctionalized alginates improve the survival rate of encapsulated embryonic stem cells during cryopreservation

Cryopreservation of stem cells, especially embryonic stem cells, is problematic because of low post-thaw cell survival rates and spontaneous differentiation following recovery. In this investigation, mouse embryonic stem cells (mESCs) were encapsulated in arginine-glycine-aspartic acid-serine (RGDS)-coupled calcium alginates (1.2 percent, w/v), allowed to attach to the substratum and then cryopreserved in 10 percent (v/v) dimethyl sulfoxide (DMSO) solution at a slow cooling rate of 1 C per min. RGDS coupling to alginate was confirmed by Transmission Fourier Transform Infra-Red spectroscopy (T-FTIR) and quantified by using ninhydrin-Ultraviolet/Visible light (ninhydrin-UV/VIS) assay. Flow cytometry data showed that mESCs cryopreserved in RGDS-alginate beads had a higher expression of stem cell markers compared with cells cryopreserved in suspension or cells cryopreserved in unmodified alginates. Cell viability after thawing was assessed using trypan blue exclusion assay and monitored using Alamar blue assay for 6 hours. It was shown that post-thaw cell survival rate was significantly higher for cells encapsulated in RGDS-modified alginate (93 ± 2 percent, mean and standard error) than those in suspension (52 ± 2 percent) or in unmodified alginates (62 ± 3 percent). These results showed that cells encapsulated and attached to a substratum have better survival rate and stem cell marker expression 24 hours after cryopreservation than those in suspension. Encapsulation in RGDS-alginate was optimized for peptide concentration, cryoprotective agent loading time and cooling rate. The best result was obtained when using 12.5 mg peptide per g alginate, 30 minutes loading time and 1 C per min cooling rate.

N-n-butyl haloperidol iodide preserves cardiomyocyte calcium homeostasis during hypoxia/ischemia

AIMS

N-n-Butyl haloperidol iodide (F(2)) is a novel compound derived from haloperidol. In our previous work, F(2) was found to be an L-type calcium channel blocker which played a protective role in rat heart ischemic-reperfusion injury in a dose-dependent manner. In the current study, we aimed to investigate the effects and some possible mechanisms of F(2) on calcium transients in hypoxic/ischemic rat cardiac myocytes.

METHODS AND RESULTS

Calcium transients' images of rat cardiac myocytes were recorded during simulated hypoxia, using a confocal calcium imaging system. The amplitude, rising time from 25% to 75% (RT25-75), decay time from 75% to 25% (DT75-25) of calcium transients, and resting [Ca(2+)](i) were extracted from the images by self-coding programs. In this study, hypoxia produced a substantial increase in diastolic [Ca(2+)](i) and reduced the amplitude of calcium transients. Both RT25-75 and DT75-25 of Ca(2+) transients were significantly prolonged. And F(2) could reduce the increase in resting [Ca(2+)](i)and the prolongation of RT25-75 and DT75-25 of Ca(2+) transients during hypoxia. F(2) also inhibited the reduction in amplitude of calcium transients which was caused by 30-min hypoxia. The activity of SERCA2a (sarcoplasmic reticulum Ca(2+)-ATPase, determined by test kits) decreased after 30-min ischemia, and intravenous F(2) in rats could ameliorate the decreased activity of SERCA2a. The inward and outward currents of NCX (recorded by whole-cell patch-clamp analysis) were reduced during 10-min hypoxia, and F(2) further inhibited the outward currents of NCX during 10-min hypoxia. All these data of SERCA2a and NCX might be responsible for the changes in calcium transients during hypoxia.

CONCLUSION

Our data suggest that F(2) reduced changes in calcium transients that caused by hypoxia/ischemia, which was regarded to be a protective role in calcium homeostasis of ventricular myocytes, probably via changing the function of SERCA2a.

Spatiotemporal dynamics of rhythmic spinal interneurons measured with two-photon calcium imaging and coherence analysis

In rhythmic neural circuits, a neuron often fires action potentials with a constant phase to the rhythm, a timing relationship that can be functionally significant. To characterize these phase preferences in a large-scale, cell type-specific manner, we adapted multitaper coherence analysis for two-photon calcium imaging. Analysis of simulated data showed that coherence is a simple and robust measure of rhythmicity for calcium imaging data. When applied to the neonatal mouse hindlimb spinal locomotor network, the phase relationships between peak activity of >1,000 ventral spinal interneurons and motor output were characterized. Most interneurons showed rhythmic activity that was coherent and in phase with the ipsilateral motor output during fictive locomotion. The phase distributions of two genetically identified classes of interneurons were distinct from the ensemble population and from each other. There was no obvious spatial clustering of interneurons with similar phase preferences. Together, these results suggest that cell type, not neighboring neuron activity, is a better indicator of an interneuron's response during fictive locomotion. The ability to measure the phase preferences of many neurons with cell type and spatial information should be widely applicable for studying other rhythmic neural circuits.

[Determination of prim-O-glucosylcimifugin and 5-O-methylvisammisoide in Saposhnikovia divaricata and HPLC fingerprint analysis]

OBJECTIVE

To develop HPLC methods for the determination of prim-O-glucosylcimifugin and 5-O-methylvisammisoide in Saposhnicovia divaricata and of HPLC fingerprint to compare the wild and culture varieties.

METHOD

Conditions of determination: Shimadzu C18 column (4.6 mm x 150 mm, 5 microm), methanol-water (40:60) as mobile phase with the flow rate of 1 mL x min(-1). The detection wavelength was 254 nm. Conditions of HPLC fingerprint: MG II C18 column (4.6 mm x 250 mm, 5 microm), the mobile phase was acetonitrile-water with the flow rate of 1 mL x min(-1), using linear gradient elution, the column temperature was 30 degrees C.

RESULT

The average recovery of prim-O-glucosylcimifugin was 99.6% (RSD 0.72%, n=6). The average recovery of 5-O-methylvisammisoide was 102.6% (RSD 0.88%, n=6). The contents of prim-o-glucosylcimifugin in wild and culture varieties were (4.96 +/- 2.59) and (3.61 +/- 1.82) mg x g(-1) respectively. The contents of 5-O-methylvisammisoide were (3.91 +/- 2.09) and (4.37 +/- 2.02) mg x g(-1) respectively. The compositions of S. divaricata were effective separated under the conditions of HPLC fingerprint.

CONCLUSION

The HPLC determination method of prim-O-glucosylcimifugin and 5-O-methylvisammisoide is convenient and accurate. The HPLC fingerprint analysis method could be a basis for quality control and classification evaluate of S. divaricata.

Occurrence of anthropogenic and naturally-produced organohalogenated compounds in tissues of Black Sea harbour porpoises

Harbour porpoises are one of the three cetacean species inhabiting the Black Sea. This is the first study to report on polybrominated diphenyl ethers (PBDEs) and naturally-produced compounds, methoxylated PBDEs (MeO-PBDEs) and polybrominated hexahydroxanthene derivatives (PBHDs), in tissues (kidney, brain, blubber, liver, muscle) of male harbour porpoises (11 adults, 9 juveniles) from the Black Sea. Lipid-normalized concentrations decreased from muscle>blubber>liver>kidney>brain for the sum of polychlorinated biphenyls (PCBs) and for the sum of PBDEs. Among the naturally-produced compounds, levels of PBHDs were higher than of MeO-PBDEs, with tri-BHD and 6-MeO-BDE 47 being the dominant compounds for both groups, respectively. Concentrations of naturally-produced compounds decreased from blubber to brain, similarly to the sum of DDT and metabolites (DDXs). Concentrations of DDXs were highest, followed by PCBs, HCB, PBHDs, PBDEs and MeO-PBDEs. Levels of PCBs and PBDEs in blubber were lower than concentrations reported for harbour porpoises from the North Sea, while concentrations of DDXs were higher.

Synthesis and biological activity of a fluorescent schweinfurthin analogue

Most of the natural schweinfurthins are potent and selective inhibitors of cell growth as measured by the National Cancer Institute's 60-cell line screen. Due to the limited supply of these natural products, we have initiated a program aimed at their synthesis. To date, this effort has led to the preparation of three natural schweinfurthins and more than 40 analogues, and assays on these compounds have afforded some understanding of structure-activity relationships in this family. Further development of schweinfurthins as chemotherapeutic agents would benefit from characterization of their mechanism(s) of action. This perspective led to development of a fluorescent schweinfurthin analogue that retains the differential activity of the natural products, and yet has properties that facilitate its visualization within cells.

[The optimization of methods utilized for testing the antibacterial activity of essential oils]

The antibacterial activity of essential oils: Lavandulae aetherleum, Limonis aetherleum and Melaleucae aetherleum was determined against Staphylococcus aureus Gram (+) and Escherichia coli Gram (-) bacteria, using four methods: agar diffusion (paper disk and agar wells) and broth dilution (turbidimetric and rezazurin reduction assay). This study revealed that the sensitivity of the agar diffusion techniques was much lower than the broth dilution methods. This was mainly due to partitioning of the oil components in the agar according to their affinity with water. This limitation could be lessened by the selection of suitable oil emulsifier/solvent, which itself not influence the bacterial growth. By initial oil solubilization with 96% ethanol (1:1), the increase of agar dilution methods sensitivity could be achieved. The broth microdilution methods, using 0.5% Tween 20 or 0.15% agar to emulsify the oils, were optimized and shown to be most accurate for testing their antimicrobial activity. By introducing resazurin, as an MIC endpoint indicator, the sensitivity of these methods was further enhanced.

Propidium iodide-based methods for monitoring drug action in the kinetoplastidae: comparison with the Alamar Blue assay

The urgent need for new drug development for African trypanosomiasis is widely recognized. This requires reliable and informative high-throughput assays. Currently, drug action is determined with a fluorimetric/colorimetric assay based on the metabolism of the dye Alamar Blue (resazurin) by live cells. However, this assay does not easily distinguish between cell death and growth arrest, or supply information about the rate at which test compounds affect these parameters. We report here an alternative fluorimetric assay, based on the interaction of propidium iodide with DNA, that allows either real-time monitoring of cell viability or the generation of EC(50) values at a predetermined time-point. The assay is highly sensitive and fluorescence readings easily correlate to numbers of parasites or DNA content. The EC(50) values were highly similar to those obtained with the standard Alamar Blue assay. The procedure lends itself readily to applications in drug development or resistance monitoring.

[Investigation on one-pot extraction of active ingredient group from Yupingfeng powder by HPLC]

The extraction of active ingredient group, i.e., prim-o-glucosylcimifugin, astragaloside, and 5-o-methylvisammiosode from Yupingfeng powder with one-pot method was studied in this work. A HPLC method was used to determine the content of each active constituent mentioned above in the extract. The influences of extraction temperature, time, volume percent of ethanol in water and its amount added on the content and yield of active ingredient group were investigated by orthogonal test. The experimental results showed that the optimized extraction conditions were as follows: 1g of Yupingfeng powder was one-pot extracted for 4 hours at 80 degrees C with 90% ethanol as solvent, and the yield and content of active ingredient group were 0.16%, 0.53% respectively. The active ingredient group in Yupingfeng powder could be effectively one-pot extracted under the conditions above.

Negative inotropy of the gastric proton pump inhibitor pantoprazole in myocardium from humans and rabbits: evaluation of mechanisms

BACKGROUND

Proton pump inhibitors are used extensively for acid-related gastrointestinal diseases. Their effect on cardiac contractility has not been assessed directly.

METHODS AND RESULTS

Under physiological conditions (37 degrees C, pH 7.35, 1.25 mmol/L Ca2+), there was a dose-dependent decrease in contractile force in ventricular trabeculae isolated from end-stage failing human hearts superfused with pantoprazole. The concentration leading to 50% maximal response was 17.3+/-1.3 microg/mL. Similar observations were made in trabeculae from human atria, normal rabbit ventricles, and isolated rabbit ventricular myocytes. Real-time polymerase chain reaction demonstrated the expression of gastric H+/K+-adenosine triphosphatase in human and rabbit myocardium. However, measurements with BCECF-loaded rabbit trabeculae did not reveal any significant pantoprazole-dependent changes of pH(i). Ca2+ transients recorded from field-stimulated fluo 3-loaded myocytes (F/F0) were significantly depressed by 10.4+/-2.1% at 40 microg/mL. Intracellular Ca2+ fluxes were assessed in fura 2-loaded, voltage-clamped rabbit ventricular myocytes. Pantoprazole (40 microg/mL) caused an increase in diastolic [Ca2+]i by 33+/-12%, but peak systolic [Ca2+]i was unchanged, resulting in a decreased Ca2+ transient amplitude by 25+/-8%. The amplitude of the L-type Ca2+ current (I(Ca,L)) was reduced by 35+/-5%, and sarcoplasmic reticulum Ca2+ content was reduced by 18+/-6%. Measurements of oxalate-supported sarcoplasmic reticulum Ca2+ uptake in permeabilized cardiomyocytes indicated that pantoprazole decreased Ca2+ sensitivity (Kd) of sarcoplasmic reticulum Ca2+ adenosine triphosphatase: control, Kd=358+/-15 nmol/L; 40 microg/mL pantoprazole, Kd=395+/-12 nmol/L (P<0.05). Pantoprazole also acted on cardiac myofilaments to reduced Ca2+-activated force.

CONCLUSIONS

Pantoprazole depresses cardiac contractility in vitro by depression of Ca2+ signaling and myofilament activity. In view of the extensive use of this agent, the effects should be evaluated in vivo.

Polybrominated hexahydroxanthene derivatives (PBHDs) and other halogenated natural products from the Mediterranean sponge Scalarispongia scalaris in marine biota

Structures of polybrominated hexahydroxanthene derivatives (PBHDs) previously detected in commercial fish from the Mediterranean Sea and mussels from New Zealand were assigned to 2,7-dibromo-4a-bromomethyl-1,1-dimethyl-2,3,4,4a,9,9a-hexahydro-1H-xanthene (TriBHD) and 2,5,7-tribromo-4a-bromomethyl-1,1-dimethyl-2,3,4,4a,9,9a-hexahydro-1H-xanthene (TetraBHD) by comparing their gas chromatography/mass spectrometry (GC/MS) features with isolates from an Australian sponge of the Cacospongia genus. Because of the geographic distance between the Mediterranean Sea in Europe (origin of the fish) and Australia (origin of the sponge), a closely related sponge, Scalarispongia scalaris, was collected in the Mediterranean Sea and analyzed for PBHDs and other halogenated compounds. The Mediterranean sponge contained the PBHDs at 37 mg/kg dry weight. Using quantitative standards for the first time, the PBHD concentrations in fish and mussel samples published earlier were re-examined. Concentrations of up to 1 mg/kg TriBHD and 0.5 mg/kg TetraBHD were determined in the lipids. No correlation with 2,2', 4,4', 5,5'-hexachlorobiphenyl (PCB 153) or p,p'-DDE was found, which is in agreement with other marine halogenated natural products detected in the fish samples. Besides the PBHDs, further unknown halogenated compounds were detected in the Mediterranean sponge, some of which were also detected in commercial fish. GC/electron ionization-MS analysis showed that a major mixed-halogenated compound in the sponge had a molecular ion at m/z 480 and contained three bromines, three chlorines, and 9-10 carbons. No corresponding structure has been described for this feature in the scientific literature. This sponge secondary metabolite and potential novel halogenated natural product was also detected in commercial fish. Another prominent mixed halogenated compound detected both in sponge and fish was the dibromotrichloro monoterpene MHC-1 (C(10)H(13)Br(2)Cl(3)).

[Studies on flavonoids from stems and leaves of Calophyllum inophyllum]

OBJECTIVE

To study the chemical constituents from the stems and leaves of Calophyllum inophyllum.

METHOD

The compounds were isolated by column chromatography on silica gel, Sephadex LH-20 and preparative TLC. Their structures were elucidated by chemical methods and NMR, MS spectroscopic data.

RESULT

Nine compounds were identified as 2-hydroxyxanthone (1), 4-hydroxyxanthone (2), 1, 5-dihydroxyxanthone (3), 1, 7-dihydroxyxanthone (4), 1, 3, 5-trihydroxy-2-methoxyxanthone (5), 6-deoxyjacareubin (6), amentoflavone (7), kaempferol-3-O-alpha-L-rhamnoside (8) and quercetin-3-O-alpha-L-rhamnoside (9).

CONCLUSION

Compounds 8 and 9 were isolated from the genus Calophyllum and compounds 1, 2, 4-6 were isolated from this plant for the first time.

A microfluidic-based system for analysis of single cells based on Ca2+ flux

A microfluidic format-based system has been developed for in situ monitoring of the calcium flux response to agonists using Chinese hamster ovary (CHO) cells. The assay is based on measuring the fluorescent intensity of the calcium-sensitive indicator, Fluo-4 AM, and was performed in a modified glass chip channel, whose surface was functionalised using a silanisation method with 3-aminopropyltriethoxysilane (APTS) (enabling the cells to be immobilised on the channel surface). CHO cells calcium flux response was measured for different agonists over a range of concentrations. Cells and reagents were introduced into the chip in a continuous flow as a series of plugs in a given sequence.

[Simultaneous analysis of six effective components in the anti-Alzheimer's disease effective component group of Xiao-Xu-Ming Decoction]

A method based on high performance liquid chromatography (HPLC) was developed for the quantitative determination of six components in an anti-Alzheimer medicine, Xiao-Xu-Ming Decoction, which is an effective prescription in treating stroke and the sequela of stroke by herbalist doctors for thousands years. The effective component group (ECG) was made according to the results of high-throughput screening, and the curative effect of ECG was validated on aging rats. In this method an ODS column was used. The mobile phase consisted of water-formic acid-ethylenediamine (A; 100: 0.1: 0.1, v/v) and methanol-formic acid (B; 100 : 0.05, v/v), eluted with gradient (0 - 5 min, 20% B; 5 - 100 min, 20% B - 40% B; 100 - 140 min, 40% B - 70% B). The flow rate was 1 mL/min. The detection wavelength was set at 240 nm. Under the above separation conditions, six components belonged to two different categories, indicans and alkaloids, were determined simultaneously. The relationships between the concentrations and the peak areas of these six components were all linear. The recoveries of the six components were 99.1% for paeoniflorin, 99.6% for prim-O-glucosylcimifugin, 98.4% for baicalin, 99.9% for 4'-O-beta-D-glucosyl-5-O-methylvisamminol, 99.6% for fangchinoline, and 102.0% for tetrandrine. The relative standard deviations (RSD) were 1.3%, 1.4%, 0.4%, 0.8%, 0.2%, and 1.4%, respectively. This method is simple and reproducible and it can be used for the quality control of the effective component group of Xiao-Xu-Ming Decoction.

A resazurin-based biosensor for organic pollutants

A new rapid biosensor method employing the dye resazurin as an indicator of bacterial respiration has been developed to provide a rapid, facile and specific biosensor for environmental contaminants that does not rely on genetic modification techniques, is suitable for a high-throughput multiwell format, and is ideally suited to resource-constrained environmental monitoring situations. This whole-cell biosensor has been applied to the test analyte toluene using natural toluene-degrading bacteria as the biological component and is competitive with more complex recombinant approaches. The redox-driven biosensor is dependent on the catabolism of a specific compound, concomitantly reducing the redox indicator resazurin to provide the analytical signal in a whole-cell biosensor assay.

Identification and quantification of polybrominated hexahydroxanthene derivatives and other halogenated natural products in commercial fish and other marine samples

During routine analysis of commercial fish on halogenated pollutants, an unknown tribromo component (TriBHD) was initially detected as an abundant peak in sample extracts from the Mediterranean Sea. The molecular formula was established to be C16H19Br3O by gas chromatography with electron ionization high-resolution mass spectrometry (GC/EI-HRMS). GC/EI-MS data were virtually identical with a polybrominated hexahydroxanthene derivative (PBHD) previously isolated from an Australian sponge species known to occur in the Mediterranean Sea as well. A tetrabromo isomer (TetraBHD) was also found in the fish samples. The concentrations of TriBHD and other halogenated compounds in commercial fish (sea bass, gilt head bream, anchovy, sardine, and salmon) were estimated with GC/electron capture detection (ECD). Using the ECD response of trans-nonachlor, the concentration of TriBHD reached up to 90 ng/g lipid weight and accounted for up to >90% of the concentration of p,p'-DDE, which was the most abundant peak in the most samples investigated. On the basis of the GC/ECD response, TetraBHD amounted for approximately 1/7 of TriBHD in all fish samples investigated. The sample with the highest content was a green-lipped mussel from New Zealand (236 ng/g lipid weight). The halogenated natural products TBA, Q1, and MHC-1 were also present in most of the samples. We assume that the bulk of the residues in fish from aquaculture may originate from algae and sponges living in proximity of the fish farms. Detection of TriBHD and TetraBHD in blubber of a monk seal (Monachus monachus) suggests that both HNPs may reach the top predators of food webs and thus also humans.

[Determination of four components in root of Saposhnikovia divaricata by HPLC gradient elution]

OBJECTIVE

To develop an HPLC method for determination of components in root of Saposhnikovia divaricata.

METHOD

The separation of four components was achieved on a reversed-phase Alltima C18 column with MeOH-H2O gradient elution at a flow rate of 1.0 mL x min(-1).

RESULT

Six samples were determined and there is no distinct difference between the contents determined by the new and old methods.

CONCLUSION

The new method is more simple and convenient than the old method.

Functional Characterisation of Homomeric Ionotropic Glutamate Receptors GluR1-GluR6 in a Fluorescence-Based High Throughput Screening Assay

We have constructed stable HEK293 cell lines expressing the rat ionotropic glutamate receptor subtypes GluR1(i), GluR2Q(i), GluR3(i), GluR4(i), GluR5Q and GluR6Q and characterised the pharmacological profiles of the six homomeric receptors in a fluorescence-based high throughput screening assay using Fluo-4/AM as a fluorescent Ca2+ indicator. In this assay, the pharmacological properties of nine standard GluR ligands correlated nicely with those previously observed in electrophysiology studies of GluRs expressed in Xenopus oocytes or mammalian cells. The potencies and efficacies displayed by the agonists (S)-glutamate, (S)-quisqualate, kainate, (RS)-AMPA, (RS)-ATPA, (RS)-ACPA] and (S)-4-AHCP at the six GluRs were in concordance with electrophysiological studies. Furthermore, the Ki values exhibited by the competitive antagonists NBQX and (RS)-ATPO were also in agreement with findings of previous studies. Finally, the effects of various concentrations of Ca2+ in the assay buffer and of the allosteric modulators cyclothiazide and concanavalin A on GluR signalling were examined. This study represents the most elaborate functional characterisation of multiple AMPA and KA receptor subtypes in the same assay reported to date. We propose that high throughput screening of compound libraries at the six GluR-HEK293 cell lines could be helpful in the search for structurally and pharmacologically novel ligands acting at the receptors.

Screening Mercury Levels in Fish with a Selective Fluorescent Chemosensor

Societal concerns over toxic mercury accumulation in humans from fish and other dietary and environmental sources provide motivation to develop new tools and tactics for mercury detection in a wide range of laboratory and field settings. Here we report the synthesis, properties, and application of a selective and sensitive small-molecule chemosensor for fluorescence screening of mercury levels in fish. Mercuryfluor-1 (MF1) is a water-soluble, fluorescein-based reagent that features excellent selectivity for Hg2+ over competing analytes and the largest turn-on fluorescence response to date (>170-fold increase) for reporting this heavy metal ion in aqueous solution. Combining this chemoselective Hg2+ probe with a microwave digestion protocol provides a facile method for assaying mercury levels in fish samples with mercury concentrations spanning 0.1 to 8 ppm, a range well matched with the United States Environmental Protection Agency (U.S. EPA) standard for the maximum safe level of mercury in edible fish (0.55 ppm).

The reduction of Alamar Blue by peripheral blood lymphocytes and isolated mitochondria

Alamar Blue is a widely used nontoxic indicator of cell proliferative activity, which penetrates quickly through the biological membranes and can be easily reduced by intracellular enzymes. Accumulation of reduced fluorescent form of Alamar Blue during short-term culture of human peripheral blood lymphocytes may be used as a cell viability test since it was prevented by disruption of plasma membrane by digitonin. The inhibition of Alamar Blue reduction by NaN3 indicates that its metabolism is associated with mitochondrial activity. A compaative study of Alamar Blue reduction and oxygen consumption on isolated rat liver mitochondria shows, that the Alamar Blue reduction is not associated with the activity of specific complex of respiratory chain and it seems to be an integral indicator of oxidation-reduction activity of respiratory chain components.

Eye pigments of the blood-sucking insect, Triatoma infestans klug (Hemiptera, Reduviidae)

The pigmentation of black (wild) and red (mutant) eyes of Triatoma infestans was studied spectrophotometrically and compared with red-eyed (wild) and white-eyed (mutant) forms of Drosophila melanogaster. The spectral absorption profiles of the black and red eye pigments of T. infestans were similar to each other and to that of the wild-type eyes of D. melanogaster. The similarity to the wild form of D. melanogaster indicated that both eye forms of T. infestans contained ommochromes of the xanthommatin type, a finding confirmed by ascending paper chromatography. Pteridines, melanins, and ommins were not detected as eye pigments in T. infestans. The eye color difference in T. infestans was assumed to be a function of the xanthommatin concentration, with a smaller content of ommochrome in red eyes, although this probably did not affect the insect's visual acuity. These data support other findings regarding the similarities between black- and red-eyed specimens of T. infestans for other characteristics.

Novel fluo-4 analogs for fluorescent calcium measurements

We report new fluorescent calcium indicators based on fluo-4. Attachment of a carboxamide or methylenecarboxamide moiety to the BAPTA chelator portion of fluo-4 allowed for the attachment of dextrans, protein-reactive moieties, and biotin. In particular, a high affinity fluo-4 dextran conjugate was prepared and shown to be functional in brain slices. All new probes were characterized spectroscopically and exhibited large fluorescence increases upon calcium-binding. The biotinylated version of fluo-4 formed a persistent streptavidin complex which still responded to increasing calcium concentrations with a large fluorescence increase.

Viability assessment in sandwich-cultured rat hepatocytes after xenobiotic exposure

Troglitazone, bosentan and glibenclamide inhibit the bile salt export pump (Bsep) which transports taurocholate into bile. Sandwich-cultured rat hepatocytes maintain functional sodium taurocholate co-transporting polypeptide and Bsep transport proteins, and may be useful to study inhibition of transport by xenobiotics at concentrations below the lowest observable adverse effect level (LOAEL). The purpose of this study was to compare viability assessments determined with the neutral red, lactate dehydrogenase (LDH), alamar blue, 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) and propidium iodide assays in sandwich-cultured rat hepatocytes following exposure to xenobiotics known to inhibit Bsep, and to define the LOAEL for these xenobiotics in this system. The neutral red assay was not amenable to use in this model due to crystal formation on the collagen. Troglitazone decreased viability in every assay examined, with a LOAEL approximately 100 microM. Bosentan also decreased viability as measured by the LDH, MTT and propidium iodide assays, with a LOAEL approximately 200 microM; however, a significant decrease in viability was not observed with the alamar blue assay. Glibenclamide did not decrease viability with any assay at the xenobiotic concentrations examined in this study. Based on the results of this study, the LDH or propidium iodide assays would be the methods of choice to assess viability in sandwich-cultured rat hepatocytes after xenobiotic exposure.

Use of cellular glucose-6-phosphate dehydrogenase for cell quantitation: applications in cytotoxicity and apoptosis assays

A fluorescence-based microplate assay was developed to quantify cell death based upon the measurement of glucose-6-phosphate dehydrogenase (G6PD) activity. G6PD is a cytosolic enzyme and leaks from cells when plasma membrane integrity is compromised. In this assay, cell death is measured by correlating the activity of extracellular G6PD to the reduction of resazurin to the fluorescent product, resorufin, via a coupled-enzyme reaction. The coupled-enzyme reaction permits rapid signal amplification from small amounts of G6PD, an advantage over assays based on resazurin alone. This assay is rapid, nontoxic, and amenable to high-throughput screening. The assay has a Z' factor of 0.78.

Exposure and effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin in tree swallows (Tachycineta bicolor) nesting along the Woonasquatucket River, Rhode Island, USA

Concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in tree swallows (Tachycineta bicolor) nesting along the Woonasquatucket River northwest of Providence (RI, USA) in 2000 and 2001 were some of the highest ever reported in avian tissues. Mean concentrations in eggs ranged from 300 to >1,000 pg/g wet weight at the two most contaminated ponds, Allendale and Lyman. Mean egg concentrations at Greystone, the upstream reference pond, were 12 and 29 pg/g. Positive accumulation rates and concentrations in diet samples from 12-day-old nestlings indicated that the contamination was accumulated locally. Concentrations in diet of between 71 and 219 pg/g wet weight were more than 6 and 18 times higher than concentrations considered safe for birds (10-12 pg/g). Hatching success was negatively associated with concentration of TCDD in eggs. Only about half the eggs hatched at Allendale compared with >77% at Greystone. The national average for hatching success in successful nests is 85%. No other contaminants, such as polychlorinated biphenyls and mercury, were present in any sample at concentrations known to affect avian reproduction. Three bioindicators, half-peak coefficient of geometric variation, ethoxyresorufin-O-dealkylase activity, and brain asymmetry were assessed relative to TCDD contamination.

Cell cycle regulation of the murine 8-oxoguanine DNA glycosylase (mOGG1): mOGG1 associates with microtubules during interphase and mitosis

8-Oxoguanine DNA glycosylase (OGG1) is a major DNA repair enzyme in mammalian cells. OGG1 participates in the repair of 8-oxoG, the most abundant known DNA lesion induced by endogenous reactive oxygen species in aerobic organisms. In this study, antibodies directed against purified recombinant human OGG1 (hOGG1) or murine (mOGG1) protein were chemically conjugated to either the photosensitizer Rose Bengal or the fluorescent dye Texas red. These dye-protein conjugates, in combination with binding assays, were used to identify associations between mOGG1 and the cytoskeleton of NIH3T3 fibroblasts. Results from these binding studies showed that mOGG1 associates with the cytoskeleton by specifically binding to the centriole and microtubules radiating from the centrosome at interphase and the spindle assembly at mitosis. Similar results were obtained with hOGG1. Together results reported in this study suggest that OGG1 is a microtubule-associated protein itself or that OGG1 utilizes yet to be identified motor proteins to ride on microtubules as tracks facilitating the movement and redistribution of cytoplasmic OGG1 pools during interphase and mitosis and in response to oxidative DNA damage.

In vivo targeting of organic calcium sensors via genetically selected peptides

A library of constrained peptides that form stable folded structures was screened for aptamers that bind with high affinity to the fluorescent dye Texas red. Two selected clones had binding constants to Texas red of 25 and 80 pM as phage and binding had minimal effects on the fluorescence of Texas red. The peptides interact with distinct but overlapping regions of Texas red. One peptide bound to X-rhod calcium sensors, which share the same core fluorophore as Texas red. These dyes retained calcium sensitivity when bound to the peptide. This peptide was used to label a fusion protein with X-rhod-5F in vivo, and X-rhod sensed changes in calcium locally. Thus, minimal, constrained peptides can functionally bind to environmentally sensitive dyes or other organic agents in biological contexts, suggesting tools for in vivo imaging and analysis.

Effects of Electrical Shocks on Ca i 2+ and V m in Myocyte Cultures

Changes in intracellular calcium concentration (ΔCa i 2+ ) induced by electrical shocks may play an important role in defibrillation, but high-resolution ΔCa i 2+ measurements in a multicellular cardiac tissue and their relationship to corresponding V m changes (ΔV m ) are lacking. Here, we measured shock-induced ΔCa i 2+ and ΔV m in geometrically defined myocyte cultures. Cell strands (width=0.8 mm) were double-stained with V m -sensitive dye RH-237 and a low-affinity Ca i 2+ -sensitive dye Fluo-4FF. Shocks (E≈5 to 40 V/cm) were applied during the action potential plateau. Shocks caused transient Ca i 2+ decrease at sites of both negative and positive ΔV m . Similar Ca i 2+ changes were observed in an ionic model of adult rat myocytes. Simulations showed that the Ca i 2+ decrease at sites of ΔV + m was caused by the outward flow of I CaL and troponin binding; at sites of ΔV − m it was caused by inactivation of I CaL combined with extrusion by Na–Ca exchanger and troponin binding. The important role of I CaL was supported by experiments in which application of nifedipine eliminated Ca i 2+ decrease at ΔV + m sites. Largest ΔCa i 2+ were observed during shocks of ≈10 V/cm causing simple monophasic ΔV m . Shocks stronger than ≈20 V/cm caused smaller ΔCa i 2+ and postshock elevation of diastolic Ca i 2+ . This was paralleled with occurrence of biphasic negative ΔV m that indicated membrane electroporation. Thus, these data indicate that shocks transiently decrease Ca i 2+ at sites of both ΔV − m and ΔV + m . Outward flow of I CaL plays an important role in Ca i 2+ decrease in the ΔV + m areas. Very strong shocks caused smaller negative ΔCa i 2+ and postshock elevation of diastolic Ca i 2+ , likely caused by membrane electroporation.

Both calcium and ROS as common signals mediate Na(2)SeO(3)-induced apoptosis in SW480 human colonic carcinoma cells

Recent studies have shown that reactive oxygen species (ROS) play a crucial role in Se-induced cell apoptosis. A number of studies have demonstrated that perturbed cellular calcium homeostasis has been implicated in apoptosis. The main objective of this study was to evaluate the role of Ca(2+) in Na(2)SeO(3)-induced apoptosis and the relationship between Ca(2+) and ROS in human colonic carcinoma cells SW480. When SW480 cells were exposed to 25-100 microM Na(2)SeO(3), both cell apoptosis and growth inhibition were observed by flow cytometric analysis and 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay. Na(2)SeO(3) was able to induce increase of [Ca(2+)](i) and ROS production and disrupt mitochondrial membrane potential (Delta Psi m) in SW480 cells monitored by using a confocal laser scanning microscope. Ca(2+) channel inhibitor CoCl(2) and an intracellular Ca(2+) chelator o-phtalaldehyde, 1,2-bis(2-aminophenoxy)-ethane-N,N,N',N'-tetra-acetic acid acetoxymethyl ester (BAPTA) completely inhibited [Ca(2+)](i) increase, but catalase had no effect on Na(2)SeO(3)-induced increase of [Ca(2+)](i). BAPTA-AM, CoCl(2), and mitochondrial Ca(2+) uptake inhibitor ruthenium red blocked Delta Psi m dissipation. The increase of ROS was also suppressed by CoCl(2), BAPTA, ruthenium red, N-acetylcysteine and catalase, respectively. The mitochondrial uncoupler carbonyl cyanide p-(trifluoromethoxy) phenylhydrazone (FCCP) completely inhibited Na(2)SeO(3)-induced ROS increase. This showed that ROS increase is due to mitochondrial Ca(2+) overload. The Na(2)SeO(3)-induced apoptosis of SW480 cells was also inhibited by CoCl(2), BAPTA, ruthenium red, N-acetylcysteine, and catalase, respectively. The results mentioned above imply that both calcium and Ca(2+)-dependent ROS as a signal molecule mediate apoptosis induced by Na(2)SeO(3) in SW480 cells.

Folate deficiency and homocysteine induce toxicity in cultured dorsal root ganglion neurons via cytosolic calcium accumulation

Folate deficiency induces neurotoxicity by multiple routes, including increasing cytosolic calcium and oxidative stress via increasing levels of the neurotoxin homocysteine (HC), and inducing mitochondrial and DNA damage. Because some of these neurotoxic effects overlap with those observed in motor neuron disease, we examined the impact of folate deprivation on dorsal root ganglion (DRG) neurons in culture. Folate deprivation for 2 h increased cytosolic calcium and reactive oxygen species (ROS) and impaired mitochondrial function. Treatment with nimodipine [an L voltage-sensitive calcium channel (LVSCC) antagonist], MK-801 (an NMDA channel antagonist) and thapsigarin (an inhibitor of efflux of calcium from internal stores) indicated that folate deprivation initially induced calcium influx via the LVSCC, with subsequent additional calcium derived from NMDA channels and internal stores. These compounds also reduced ROS and mitochondrial degeneration, indicating that calcium influx contributed to these phenomena. Calcium influx was prevented by co-treatment with 3-deaza-adenosine, which inhibits HC formation, indicating that HC mediated increased cytosolic calcium following folate deprivation. Nimodipine, MK-801 and thapsigargin had similar effects following direct treatment with HC as they did following folate deprivation. These findings support the idea that folate deprivation and HC treatment can compromise the health of DRG neurons by perturbing calcium homeostasis.

Hg2+ signaling in trout hepatoma (RTH-149) cells: involvement of Ca2+-induced Ca2+ release

Mercury is a non-essential heavy metal affecting intracellular Ca2+ dynamics. We studied the effects of Hg2+ on [Ca2+]i in trout hepatoma cells (RTH-149). Confocal imaging of fluo-3-loaded cells showed that Hg2+ induced dose-dependent, sustained [Ca2+]i transient, triggered intracellular Ca2+ waves, stimulated Ca2+-ATPase activity, and promoted InsP3 production. The effect of Hg2+ was reduced by the Ca2+ channel blocker verapamil and totally abolished by extracellular GSH, but was almost unaffected by cell loading with the heavy metal chelator TPEN or esterified GSH. In a Ca2+-free medium, Hg2+ induced a smaller [Ca2+]i transient, that was unaffected by TPEN, but was abolished by U73122, a PLC inhibitor, and by cell loading with GDP-betaS, a G protein inhibitor, or heparin, a blocker of intracellular Ca2+ release. Data indicate that Hg2+ induces Ca2+ entry through verapamil-sensitive channels, and intracellular Ca2+ release via a G protein-PLC-InsP3 mechanism. However, in cells loaded with heparin and exposed to Hg2+ in the presence of external Ca2+, the [Ca2+]i rise was maximally reduced, indicating that the global effect of Hg2+ is not a mere sum of Ca2+ entry plus Ca2+ release, but involves an amplification of Ca2+ release operated by Ca2+ entry through a CICR mechanism.

Vesl/Homer proteins regulate ryanodine receptor type 2 function and intracellular calcium signaling

Cellular signaling proteins such as metabotropic glutamate receptors, Shank, and different types of ion channels are physically linked by Vesl (VASP/Ena-related gene up-regulated during seizure and LTP)/Homer proteins [Curr. Opin. Neurobiol. 10 (2000) 370; Trends Neurosci. 23 (2000) 80; J. Cell Sci. 113 (2000) 1851]. Vesl/Homer proteins have also been implicated in differentiation and physiological adaptation processes [Nat. Neurosci. 4 (2001) 499; Nature 411 (2001) 962; Biochem. Biophys. Res. Commun. 279 (2000) 348]. Here we provide evidence that a Vesl/Homer subtype, Vesl-1L/Homer-1c (V-1L), reduces the function of the intracellular calcium channel ryanodine receptor type 2 (RyR2). In contrast, Vesl-1S/Homer-1a (V-1S) had no effect on RyR2 function but reversed the effects of V-1L. In live cells, in calcium release studies and in single-channel electrophysiological recordings of RyR2, V-1L reduced RyR2 activity. Important physiological functions and pharmacological properties of RyR2 are preserved in the presence of V-1L. Our findings demonstrate that a protein-protein interaction between V-1L and RyR2 is not only necessary for organizing the structure of intracellular calcium signaling proteins [Curr. Opin. Neurobiol. 10 (2000) 370; Trends Neurosci. 23(2000)80; J. Cell Sci. 113 (2000) 1851; Nat Neurosci. 4 (2001) 499; Nature 411 (2001) 962; Biochem. Biophys. Res. Commun. 279 (2000) 348; Nature 386 (1997) 284], but that V-1L also directly regulates RyR2 channel activity by changing its biophysical properties. Thereby it may control cellular calcium homeostasis. These observations suggest a novel mechanism for the regulation of RyR2 and calcium-dependent cellular functions.

Identification of flavonol and xanthone glycosides from mango (Mangifera indica L. Cv. "Tommy Atkins") peels by high-performance liquid chromatography-electrospray ionization mass spectrometry

Flavonol O- and xanthone C-glycosides were extracted from mango (Mangifera indica L. cv. "Tommy Atkins") peels and characterized by high-performance liquid chromatography-electrospray ionization mass spectrometry. Among the fourteen compounds analyzed, seven quercetin O-glycosides, one kaempferol O-glycoside, and four xanthone C-glycosides were found. On the basis of their fragmentation pattern, the latter were identified as mangiferin and isomangiferin and their respective galloyl derivatives. A flavonol hexoside with m/z 477 was tentatively identified as a rhamnetin glycoside, which to the best of our knowledge, has not yet been reported in mango peels. The results obtained in the present study confirm that peels originating from mango fruit processing are a promising source of phenolic compounds that might be recovered and used as natural antioxidants or functional food ingredients.

A validated HPLC method for the assay of xanthone and 3-methoxyxanthone in PLGA nanocapsules

This work relates the development and validation of a simple reversed-phase high-performance liquid chromatographic (HPLC) method for the analysis of xanthone (XAN) and 3-methoxyxanthone (3-MeOXAN) in poly(D,L-lactide-co-glycolide) (PLGA) nanocapsule formulations. This method does not require any complex sample extraction procedure. Chromatographic separation is made with a reversed-phase C(18) column, using methanol-water (90:10, v/v) as a mobile phase at a flow rate of 1 mL/min. Identification is made by UV detection at 237 nm. The isocratic system operates at ambient temperature and requires 7 min of chromatographic time. The developed method is statistically validated according to United States Pharmacopoeia 25 and International Conference on Harmonization guidelines for its specificity, linearity, accuracy, and precision. The assay method proposed in this study is specific for XAN and 3-MeOXAN in the presence of nanocapsule excipients. Diode-array analyses confirm the homogeneity of XAN and 3-MeOXAN peaks in stressed conditions. Standard curves are linear (r > 0.999) over the concentration range of 0.4-2.5 and 1.0-5.8 micro g/mL for XAN and 3-MeOXAN, respectively. Recovery from nanocapsules ranges from 99.6% to 102.8% for XAN and 98.8% to 102.4% for 3-MeOXAN. Repeatability (intra-assay precision) is acceptable with relative standard deviation values of 1.2% for XAN and 0.3% for 3-MeOXAN.

Optical encoding with shaped DAM-1 molecular sieve particles

This work introduces a new high-throughput screening particle - a Dallas Amphorous Material No. 1 (DAM-1) molecular sieve particle. In contrast to porous silica microspheres, the 2-8-microm sized DAM-1 molecular sieve particles are available in a variety of shapes and morphologies including spheres, hexagons, rods, gyroids, and discoids. The advantage of using DAM-1 molecular sieve particles is the ability to encode an array by particle shape, which in turn permits the repeated use of luminescent reporter dyes. In this technical note, we demonstrate optical decoding of fluorescein- and Texas Red-modified shaped molecular sieve particles using reflectance and fluorescence microscopies.

Excitation-dependent intracellular Ca2+ waves at the border zone of the cryo-injured rat heart revealed by real-time confocal microscopy

Intracellular Ca2+ waves, which develop under Ca2+-overloaded conditions of the injured myocardium, are regarded as an important substrate for triggered arrhythmias. However, little is known about whether Ca2+ waves arise or become proarrhythmic in the injured heart in situ. On the hypothesis that injured myocardium manifests frequent Ca2+ waves and produce an oscillatory [Ca2+]i rise leading to triggered activity, we applied cryo-injury to the epicardial surface of fluo 3-AM-loaded perfused rat hearts and analyzed spatiotemporal [Ca2+]i changes at border zones of the injured myocardium using real-time confocal microscopy. In intact regions Ca2+ waves barely emerged, whereas the border zone myocardium exhibited frequent Ca2+ waves, propagating randomly within the individual cells. Two different types of Ca2+ waves were identified: highly frequent waves (159.6+/-86.5 waves/min/cell, n=266) adjacent to the cryo-ablated regions, and less frequent waves (79.0+/-50.1 waves/min/cell, n=160) slightly farther (>2 cells) away from the ablated regions (vicinities). The former Ca2+ waves emerged asynchronously to Ca2+ transients. Contrariwise, the latter depended on ventricular excitation: they vanished instantaneously on Ca2+ transients, but emerged more frequently and propagated more swiftly after cessation of higher-frequency pacing. Immediately after 3-Hz pacing, some cryo-injured hearts exhibited oscillatory [Ca2+]i rises; an instantaneous and synchronous elevation of [Ca2+]i followed by burst occurrence of Ca2+ waves with a gradual decrease in incidence and propagation velocity in a considerable number of cells. These observations indicate that myocardial injury induces Ca2+ waves in the heart, and that their synchronous occurrence could become a substrate for triggered arrhythmias.

Xanthones from the heartwood of Garcinia mangostana

Twelve xanthones were isolated from the hexane extract of the heartwood of Garcinia mangostana from Myanmar. Their structures were determined using 1D and 2D NMR techniques

Physiological study of interstitial cells of Cajal identified by vital staining

Interstitial cells of Cajal (ICC) form networks that intercalate between the enteric nervous system and smooth muscle cells and play a fundamental role in the control of gastrointestinal motility by initiating rhythmic electrical activity. In this report, we used a method to examine the physiological and morphological properties of ICC in living, intact tissues. ACK2, an anti-Kit antibody, was conjugated to a fluorescent probe and used to identify individual ICC for intracellular electrical recordings, to record changes in intracellular calcium concentration using fluorescent dyes and for confocal microscopy. Cyclic changes in intracellular calcium concentration were recorded in ICC with a frequency similar to the electrical slow wave. In addition, injection of a fluorescent dye into single ICC enabled the three-dimensional reconstruction of single myenteric plexus ICC within the intact network. The data show that ICC in intact networks from the myenteric plexus region in living tissues in the guinea-pig antrum exhibit an electrical slow wave, and that intracellular calcium oscillates at a frequency similar to the slow wave.

Isolation and quantitative analysis of phenolic antioxidants, free sugars, and polyols from mango (Mangifera indica L.) stem bark aqueous decoction used in Cuba as a nutritional supplement

An aqueous decoction of mango (Mangifera indica L.) stem bark has been developed in Cuba on an industrial scale to be used as a nutritional supplement, cosmetic, and phytomedicine. Previously we reported its antioxidant activity, and we concluded that the product could be useful to prevent the production of reactive oxygen species and oxidative tissue damage in vivo. A phytochemical investigation of mango stem bark extract has led to the isolation of seven phenolic constituents: gallic acid, 3,4-dihydroxy benzoic acid, gallic acid methyl ester, gallic acid propyl ester, mangiferin, (+)-catechin, (-)-epicatechin, and benzoic acid and benzoic acid propyl ester. All structures were elucidated by ES-MS and NMR spectroscopic methods. Quantitative analysis of the compounds has been performed by HPLC, and mangiferin was found to be the predominant component. Total polyphenols were assayed also by the Folin-Ciocalteu method. The free sugars and polyols content was also determined by GC-MS.

Methoxylated xanthones in the quality control of small centaury (Centaurium erythraea) flowering tops

In the course of a phytochemical study of the bitter tonic plant, small centaury (Centaurium erythraea), six methoxylated xanthones (1,5-hydroxy-3-methoxyxanthone, 1-hydroxy-3,5,6-trimethoxyxanthone, 1-hydroxy-3,5,6,7-tetramethoxyxanthone, 1-hydroxy-3,5,6,7,8-pentamethoxyxanthone, 1-hydroxy-3,7,8-trimethoxyxanthone and 1,8-dihydroxy-3,5,6,7-tetramethoxyxanthone) were isolated and identified by spectroscopic means (nuclear magnetic resonance, mass spectroscopy, and UV). Subsequently, a high-performance liquid chromatography/diode array detection method was developed for the determination of these and other methoxylated xanthones occurring in the chloroform extract of small centaury aerial parts. The methodology developed was applied to twelve samples, and in all of them, nine xanthones were identified and quantified. This methodology can be considered complimentary to the one proposed by the European Pharmacopoeia.