[Structural elucidation of a new tetrahydroxystilbene of Radix Polygoni Multiflori Preparata and study on its cardiovascular activity]

AIM

To investigate the cardiovascular active constituents of Radix Polygoni multiflori Preparata.

METHODS

Compounds were isolated from the water soluble extract with column chromatography of Sephadex, ODS and HPLC. The compounds were identified on the basis of spectral analysis (IR, EI-MS, FAB-MS, 1HNMR, 13CNMR, 2D-NMR) and phytochemical properties. Its inhibitory effect on the proliferation of bovine vascular smooth muscle cells were bioassayed in vitro.

RESULTS

One compound was isolated and identified as: 2,3,5,4'-tetrahydroxystilbene-2-O-(6"-O-alpha-D- glucopyranosyl)-beta-D-glucopyranoside.

CONCLUSION

Compound I is a new compound with cardiovascular activity.

Use of prawn blood agar hemolysis to screen for bacteria pathogenic to cultured tiger prawns Penaeus monodon

A newly developed prawn blood agar consisting of 1 ml of tiger prawn hemolymph in medium containing 200 ppm Rose Bengal was used to determine the hemolytic activity of 35 isolates of bacteria obtained from cultured tiger prawns Penaeus monodon and their rearing water. For comparison, the hemolytic activity of these isolates was also determined in sheep blood agar. Nine isolates (25.7% of total) showed different hemolytic reactions on prawn blood agar and sheep blood agar. From the 35 isolates, 8 with various hemolytic characteristics were selected and the relationship between the type of hemolytic activity and pathogenicity was determined and compared. Four isolates that showed hemolytic activity in prawn blood agar caused high mortality to cultured tiger prawns. By contrast, a significantly lower mortality rate was observed for tiger prawns injected with 4 isolates that did not exhibit hemolytic activity on prawn blood agar. Results further showed that mortality did not correlate with hemolytic activity determined using sheep blood agar. Prawn blood agar containing P. monodon hemocytes was faster and more accurate for determining prawn hemolytic activity of bacterial isolates.

Structural studies of the glycopeptides of B-chain of cinnamomin--a type II ribosome-inactivating protein by nuclear magnetic resonance

Cinnamomin is a plant type II ribosome-inactivating protein (RIP) isolated from the seeds of Cinnamomum camphora. It consists of two nonidentical polypeptide chains (A- and B-chain) held together through one disulfide linkage. Its A- and B-chain contain 0.3% and 3.9% sugars respectively. The B-chain of cinnamomin was digested by pronase E and then the liberated glycopeptides were separated from non-glycopeptides by gel filtration chromatography on a Bio-Gel P-4 column. Three crude glycopeptides were obtained by continuing chromatography over anion-exchange resin (AG1-X2) in the buffer of 2% pyridine-acetic acid (pH 8.3) with a polygradient elution system. Through further purification by the gel filtration chromatography and HPLC, three major glycopeptides, GP1, GP2 and GP3 were obtained. Mainly by two-dimensional Nuclear Magnetic Resonance (NMR) including TOCSY, DQF-COSY, NOESY, HMQC and HMBC, their primary structures were analyzed as: Man\balpha1,3Man\balpha1,6(Man\balpha1,3)(Xyl\bbeta1,2)Man\bbeta1,4GlcNAc\bbeta1,4GlcNAc\bbeta1-(Gly-)Asn-Asn-Thr(GP1), Man\balpha1,6(Man\balpha1,3)(Xyl\bbeta1,2)Man\bbeta1,4GlcNAc\bbeta1,4(Fuc\balpha1,3)GlcNAc\bbeta1-Asn-Ala-Thr(GP2),Man\balpha1,6(Man\balpha1,3)Man\balpha1,6(Man\balpha 1,2 Man\balpha1,3)Man\bbeta1,4GlcNAc\bbeta1,4GlcNAc\bbeta1-(Ala-)Asn-Gly-Thr(GP3).

[Studies on flavone constituents of Erigeron breviscapus (Vant.) Hand.-Mazz]

OBJECTIVE

To study the chemical constituents of Erigeron breviscapus.

METHOD

The constituents were separated and purified by column chromatography with silica gel, and identified by IR, MS, NMR and physical data.

RESULT

Five compounds were isolated and identified as 3, 5, 6, 4'-tetrahydroxy-7-methoxy flavonoid(I); 5, 7, 4'-trihydroxy flavonoid(II); 3, 5, 6, 7, 4'-pentahydroxy flavonoid(III); scutellarein (IV) and 5, 7, 4'-trihydroxy flavanone(V).

CONCLUSION

Compounds I, III and V were isolated from this plant for the first time.

Three new saponins from Tribulus terrestris

Three new steroidal saponins 1-3, together with five known steroidal saponins, L-mannitol and an inorganic salt were isolated from Tribulus terrestris L. (Zygophyllaceae). The structures of the new steroidal saponins were elucidated as hecogenin 3-O-beta-xylopyranosyl(1-->3)-beta-glucopyranosyl(1-->4)-beta-galactopyr anoside (1), hecogenin 3-O-beta-glucopyranosyl(1-->2)-beta-glucopyranosyl(1-->4)- beta-galactopyranoside (2) and 3-O-[beta-xylopyranosyl(1-->2)-[beta-xylopyranosyl(1-->3)]-beta- glucopyranosyl(1-->4)-[alpha-rhamnopyranosyl(1-->2)]-beta-galactopyranos yl]- 26-O-beta-glucopyranosyl-22-methoxy-(3 beta,5 alpha,25R)-furostan-3,26-diol (3). Structure elucidation was accomplished by 1D and 2D NMR spectra (13C-1H COSY, HMQC, HMBC, 1H-1H COSY, TOCSY, and NOESY), mass spectrometry (FABMS, ESIMS) and chemical methods.

Non-specific depurination activity of saporin-S6, a ribosome-inactivating protein, under acidic conditions

Among five ribosome-inactivating proteins tested only saporin-S6 could efficiently release the adenine from adenosine 20 of the synthetic oligoribonucleotide (SRD RNA) mimic of the sarcin/ricin domain of rat 28S rRNA with a Km of 9 microM and a kcat of approximately 0.4 min(-1) at pH 7.6. The optimal pH for the depurination activity of saporin-S6 is 5.0. However, saporin-S6 lost its site-specificity of depurination on SRD RNA around the optimal pH. The non-specific depurination activity of saporin-S6 was dependent on the enzyme concentration and pH conditions. These results are valuable to understand the diversity and the depurination mechanism of ribosome-inactivating proteins.

A silent antifungal protein (AFP)-like gene lacking two introns in the mould Trichoderma viride

In cells of the mould Trichoderma viride, the existence of an antifungal protein (AFP)-like gene consisting of 285 bp was confirmed by Southern analysis that genomic DNA of T. viride could hybridize with the cDNA of mature AFP of Aspergillus giganteus MDH 18894. Except for the absence of two introns, the nucleotide sequence of the AFP-like gene was identical to that of the AFP gene of A. giganteus in positions 336-479, 568-649, and 706-765. The AFP-like gene could not be transcribed into its mRNA in T. viride cells as examined by RT-PCR using total RNAs of T. viride as template. Furthermore, AFP could not be detected either directly from the culture medium of T. viride or by Western analysis. However, the AFP-like gene could be actively expressed like the cDNA of AFP in Escherichia coli cell. Recombinant AFP exhibited similar antifungal activity as native AFP.

The pH-dependent interaction of cinnamomin with lipid membranes investigated by fluorescence methods

Cinnamomin, a new type II ribosome-inactivating protein (RIP), was found to be able to induce the release of calcein loaded in lecithin small unilamellar vesicles and the fusion or aggregation of the lecithin liposomes. Such induction could be promoted severalfold by a pH 5.0 environment, a condition similar to that in endocytic vesicles. Lowering the pH from 7.5 to 5.0 evoked conformational changes of cinnamomin and unmasked its hydrophobic areas, including the exposure of 1-anilino-8-naphthalenesulfonate (1,8-ANS) binding sites of the molecule. Some tryptophan residues with affinity to acrylamide were demonstrated to participate in the lipid-protein interaction. The pH dependent fusogenicity of type II RIP might suggest its in vivo function as a fusogen to exert its cytotoxicity.

Human gastric cancer kinase profile and prognostic significance of MKK4 kinase

Alterations of protein tyrosine kinase are often associated with uncontrolled cell growth and tumor progression. Knowledge of the overall expression pattern of tyrosine kinases should prove beneficial in understanding the signaling pathways involved in gastric cancer oncogenesis and in providing possible biomarkers for gastric cancer progression. To establish a general tyrosine-kinase expression profile, degenerated polymerase chain reaction primers designed from the consensus catalytic kinase motifs were used to amplify protein tyrosine kinase molecules from gastric cancer tissues. We observed more than 50 tyrosine and serine/threonine kinases from matching pairs of gastric cancer tissue and normal mucosa. Based on this new kinase profile information, we selected the MKK4 gene for further immunohistochemical studies. Statistical analysis of MKK4 protein expression and clinicopathological features indicated that MKK4 kinase expression could serve as a significant prognostic factor for relapse-free survival and for overall survival. We demonstrated a simple and sensitive method for establishing protein tyrosine-kinase expression profiles of human gastric cancer tissues as well as for discovering novel and useful clinical biomarkers from such kinase expression profiles.

Adenine nucleotide N-glycosidase activity of the A-chain of cinnamomin characterized by 1H-nuclear magnetic resonance

Plant ribosome-inactivating proteins specifically cleave an N-glycosidic bond of a unique adenosine in the largest ribosomal RNA, releasing an adenine from ribosomes of different sources. Here, 1H-nuclear magnetic resonance is used to analyze the enzymatic products of the A-chain of cinnamomin, a type-II ribosome-inactivating protein (RIP) acting on the nucleotides in situ. The enzymatic activities of the RIP on nine nucleotides are compared. Cinnamomin A-chain can cleave the N-glycosidic bond and release an adenine base from adenine nucleotides except 5'-ATP; however, it cannot act on 5'-GMP, 5'-CMP, and 5'-UMP. The A-chain in the mixture of cinnamomin A- and B-chain exhibits higher activity toward adenine nucleotides than the A-chain alone does, suggesting that the B-chain can conformationally stabilize the A-chain. Intact cinnamomin also exhibits lower activity toward adenine nucleotides. However, cinnamomin B-chain and heat-denatured intact cinnamomin cannot hydrolyze all the tested nucleotides. We conclude that hydrolysis of the N-C glycosidic bond of nucleotide compounds by cinnamomin A-chain has a base preference, and the negatively charged phosphate group(s) reduces the recognition ability of the A-chain to adenine nucleotide.

Toxicity of cinnamomin--a new type II ribosome-inactivating protein to bollworm and mosquito

The toxicity of cinnamomin, a new type II ribosome-inactivating protein purified from the seeds of camphor tree (Cinnamomum camphora), to bollworm (Helicoverpa armigera) and mosquito (Culex pipines pallens) during larval stage was tested. The LC50 of cinnamomin to bollworm larvae fed on diet containing cinnamomin was 1839 ppm and the LC50 to larvae of mosquito was 168 ppm. The gut extract of bollworm larvae could apparently hydrolyze cinnamomin. The inhibition of protein synthesis by cinnamomin was tested in in vitro translation system of bollworm larvae, and its LC50 was determined to be approx. 14 nM. Bollworm larvae ribosome treated with cinnamomin produced a specific RNA fragment (R-fragment) characterized on urea-denatured polyacrylamide gel. Evidence was provided that hidden breaks exist in the largest ribosomal RNA of bollworm larvae.

Effects of the active aldehyde group generated by RNA N-glycosidase in the sarcin/ricin domain of rat 28S ribosomal RNA on peptide elongation

Effects of the active aldehyde group of ribose C1' at position 4324 of rat 28S rRNA, in the inactivated ribosome generated by RNA N-glycosidases (trichosanthin, A-chain of cinnamomin and ricin), on peptide elongation have been studied. The aldehyde group inhibits the activities of eEF1A-dependent aminoacyl-tRNA binding to the inactivated ribosome and eEF1A-dependent GTPase, but increases eEF2-dependent activity. At a high concentration of RNA N-glycosidase, the generated aldehyde group also inhibits aminoacyl-tRNA binding to the inactivated ribosome in the absence of elongation factor and translocation activity. When the aldehyde group is reduced into a hydroxyl group by sodium borohydride or blocked with an amino acid through nucleophilic addition, the activities of eEF1A-dependent aminoacyl-tRNA binding and eEF1A-dependent GTPase of the inactivated ribosome are partially restored, but the altered activities of eEF2-dependent GTPase, translocation and aminoacyl-tRNA binding in the absence of elongation factor are not normalized. Thus, reduction or blockage of the aldehyde group with sodium borohydride or amino acids might change the conformation of the S/R domain in rat 28S ribosomal RNA to meet the requirement for eEF1A-dependent reactions, but not eEF2-involved reactions.

Impact of a worker notification program: assessment of attitudinal and behavioral outcomes

BACKGROUND

Hundreds of worker notification programs are conducted each year to communicate occupational risks to workers. However, few attempts have been made to evaluate their effectiveness and few have described how communication theories are applied in developing notification messages. We developed and assessed the effectiveness of a worker notification program at a beryllium machining plant.

METHODS

We compared self-protective attitudinal and behavioral responses among workers in two plants: (1) an intervention plant that received beryllium risk notification and (2) a matched control plant that did not receive notification.

RESULTS

Workers receiving notification reported significantly stronger perceptions of threat and efficacy, more positive attitudes toward safety practices, and engaged in more protective behaviors than the workers at the control plant.

CONCLUSIONS

This study demonstrates the utility of applying communication theories in the development of notification messages and the results suggest that mass presentations may be just as effective, if not more so, than one-on-one notifications. Am. J. Ind. Med. 37:205-213, 2000. Published 2000 Wiley-Liss, Inc.

Isolation and characterization of viridin, a new 65 kDa antifungal protein from the mould Trichoderma viride

A new extracellular antifungal protein with a yield of 10 mg per liter was isolated from the culture medium of the mould Trichoderma viride. The protein, which we named viridin, was purified by carboxymethyl-cellulose cation-exchange chromatography and Superose 12 HR 10/30 high-performance liquid chromatography. Viridin, a basic protein of approximately 65 kDa as determined by SDS-PAGE, inhibits the growth of the cotton pathogen Verticillum dahliae, the IC50 being 6 microM.

Ribotoxins and their applications in probing the topographical structure of ribosomes

Ribotoxins are a group of ribosome-inactivating proteins (RIPs) isolated mostly from plants. They inactivate ribosomes by a mechanism as RNA N-glycosidase that removes a specific adenine base from the highly conserved "S/R domain" in the largest ribosomal RNA. In this review, we introduce the major results from our laboratory in recent years on the study of the structure and function of RIPs and ribosomes: [1] Purification and characterization of the enzymatic mechanism of RIPs. Several new RIPs were purified and their RNA N-glycosidase and supercoil-dependent DNA endonuclease activities were studied. [2] The topographical structure of ribosomes. The relationship between the structure and function of ribosomes, especially of the "S/R domain" in rat 28S rRNA, were investigated by means of RIPs and other chemical probes. [3] The cytotoxicity of two RIPs to carcinoma cells. [4] Several new methods for studying RIPs and probing the structure of ribosomes were developed, i.e., radioassays for RNA N-glycosidase, glycoprotein detection by fluorescent labeling on SDS-polyacrylamide gels, and methods for small RNA sequencing.

Cation channel formed at lipid bilayer by Cinnamomin, a new type II ribosome-inactivating protein

Cinnamomin, a new type II ribosome-inactivating protein, purified from the seeds of Cinnamonum camphora is reconstituted into the membranes of planar lipid bilayer and giant liposome. The channel-forming activity of the cinnamomin is found and cation permeability of the channel is characterized by patch clamp. In an asymmetric solution system, bath 150/pipette 100 mM KCl, the unit conductance is 140+/-7 pS and the reversal potential is 10.4+/-0.6 mV, very close to the theoretical value of the K+ electrode. The results offer an interpretation for internalization of the RIP and the cytotoxicity difference between single and two chain RIP.

[Effect of anti-opioid peptide sera on the enhancement of electroacupuncture analgesia induced by neurotensin in PAG of rats]

With the use of potassium iontophoresis induced tail-flick for measuring the pain threshold, the effects of injecting neurotensin (NT), naloxone (NX), anti-metenkephalin serum (AMEKS), anti-beta-endorphin serum (AEPS) and anti-dynorphin A1-13 serum (ADYNS) into periaqueductal gray (PAG) on electroacupuncture (EA) analgesia in rats were investigated. NT administration enhanced EA analgesia remarkably. Pre-injection of NX, AMEKS and AEPS into PAG could significantly attenuate the enhancement of EA analgesia induced by NT, but not by administration of ADYNS. The results indicate that NT in PAG is responsible for the enhancement of EA analgesia. The effect of NT may be partly mediated by met-enkephalin and beta-endorphin.

[The result of splenopneumopexy on patients with portal hypertension in children]

OBJECTIVE

The purpose of this study was to study the effect of splenopneumopexy for patients with portal hypertension in children.

METHODS

From March 1993 to April 1998, splenopneumopexy was performed on six children with portal hypertension. Doppler ultrasound and radionuclide were used to demonstrate the portopulmonary shunt after operation.

RESULTS

The bleeding from the esophageal varices was controlled and the esophageal varices were eliminated gradually. The symptoms pertaining to hypertension were disappeared. The patency of the shunt was maintained without the formation of thrombosis. No pulmonary complication was observed.

CONCLUSION

The results indicated that splenopneumopexy was a safe and effective procedure for patients with portal hypertension in children.

Purification and characterization of trichomaglin--a novel ribosome-inactivating protein with abortifacient activity

Trichomaglin, a novel ribosome-inactivating protein, has been isolated from root tuber of a plant Maganlin (Trichosanthes Lepiniate, Cucurbitaceae). The isolation and purification procedure included ammonium sulfate precipitation, Sephadex G-75 chromatography and CM-Sephadex C-50 chromatography. The protein was identified to be homogeneous by SDS-PAGE and FPLC analysis. Its molecular weight is 24,673 dalton and isoelectric point is 5.8, determined by electrospray ionization mass spectroscopy and isoelectric focusing gel electrophoresis respectively. Trichomaglin can inhibit protein synthesis in rabbit reticulocyte lysate with ID50 of 10.1 nM. When rat ribosome was incubated with trichomaglin, a diagnostic RNA fragment appeared on polyacrylamide gel after ribosomal RNAs were treated with acidic aniline. It was concluded that trichomaglin is an RNA N-glycosidase. In addition, it has been verified to be an abortifacient protein.

Purification and activity study of the A- and B-chains of cinnamomin, a type II ribosome-inactivating protein

The strong hydrophobic interaction between the A- and B-chains of cinnamomin, a type II ribosome-inactivating protein, makes it difficult to separate A- and B-chains after the disulfide bond is broken. We failed to separate the A-chain from B-chain of cinnamomin using methods under usual conditions. A convenient method for purification of the A- and B-chains of cinnamomin on a large scale has been developed. We chose urea to weaken the non-covalent interaction between the A- and B-chains. In the presence of 4M urea, the A- and B-chains of the reduced cinnamomin are separated effectively by DEAE-cellulose chromatography. The purified A-chain still displays the RNA N-glycosidase activity and the B-chain loses the lectin activity. After refolding in vitro in the presence of lactose, the B-chain is renatured and the active B-chain with lectin activity can be further purified by Sepharose 4B affinity chromatography. From 80 mg of cinnamomin, 10 mg of A-chain (25%) and 38 mg of the B-chain (95%) were obtained. In addition, the intrinsic fluorescence spectra of the A- and B-chains were employed to study the structural changes in the active and the non-active forms of cinnamomin A- and B-chains.

Defining an antigenic epitope on platelet factor 4 associated with heparin-induced thrombocytopenia

Heparin-induced thrombocytopenia (HIT) is a potentially serious complication of heparin therapy. Antibodies to platelet factor 4 (PF4)/heparin complexes have been implicated in the pathogenesis of this disorder, but the antigenic epitope(s) on the protein have not been defined. To address this issue, we studied the binding of HIT antibodies to a series of recombinant proteins containing either point mutations in PF4 or chimeras containing various domains of PF4 and the related protein, neutrophil activating peptide-2 (NAP-2). Serum samples from 50 patients with a positive 14C-serotonin release assay (14C-SRA) and a clinical diagnosis of HIT and 20 normal controls were studied. HIT antibodies reacted strongly with wild-type (WT) PF4/heparin complexes, but reacted little, if at all, with NAP-2/heparin complexes (optical density [OD]405 = 2.5 and 0.2, respectively). Alanine substitutions at three of the four lysine residues implicated in heparin binding, K62, K65, and K66, had little effect on recognition by HIT antibodies (OD405 = 2.2, 2.8, and 2.0, respectively), whereas an alanine substitution at position K61 led to reduced, but still significant binding (OD405 = 1.0). Similar studies involving chimeras between PF4 and NAP-2 localized a major antigenic site to the region between the third and fourth cysteine residues for more than half of the sera tested. This site appears to involve a series of amino acids immediately after the third cysteine residue beginning with P37. Thus our studies suggest that whereas the C-terminal lysine residues of PF4 are important for heparin binding, they do not comprise a critical antigenic site for most HIT antibodies. Rather, we propose that maintaining a region near the third cysteine residue of PF4, distal from the proposed heparin-binding domain, is required to form the epitope recognized by many HIT antibodies.

Purification of alpha-sarcin and an antifungal protein from Aspergillus giganteus by blue sepharose CL-6B affinity chromatography

A simple method for preparation of alpha-sarcin and an antifungal protein (AFP) from the mold Aspergillus giganteus MDH 18894 has been developed. alpha-Sarcin and AFP were purified simultaneously by carboxymethylcellulose 52 cation-exchange chromatography and Blue Sepharose CL-6B affinity chromatography. By this method, 4.2 mg of alpha-sarcin and 6.8 mg of AFP were obtained from 2 liters of medium. Compared with other purification methods such as gel-filtration chromatography, this procedure was simple and specific. The purified alpha-sarcin and AFP were homogeneous characterized on SDS-polyacrylamide gel. The enzymatic activity of several ribosome-inactivating proteins such as alpha-sarcin, trichosanthin, and cinnamomin was significantly inhibited by the dye Cibacron blue F3GA. In 50 microliter of reaction mixture, 10 microM of the dye could inhibit 50% activity of cinnamomin (7 x 10(-9) M), whereas 50% inhibition of the enzymatic activity of trichosanthin (7 x 10(-9) M) and alpha-sarcin (1 x 10(-7) M) required 100 and 50 microM of the dye, respectively.

DNA-cleaving activity of superoxide dismutase specific for circular supercoiled double-stranded DNA in vitro

Several superoxide dismutases (SODs), N. tabacum Mn-SOD, porcine erythrocyte Cu/Zn-SOD and bovine erythrocyte Cu/Zn-SOD, have been found to exhibit the activity to cleave the circular supercoiled double-stranded DNA into nicked and further linear form in vitro. The fact that porcine erythrocyte Cu/Zn-SOD did not cleave the linear double-stranded DNA excluded the possibility that nuclease contaminated the SOD preparations and showing the cleaving activity was dependent on the supercoiled form of DNA. Porcine erythrocyte Cu/Zn-SOD inactivated by H2O2 or guanidine still remained its supercoiled DNA-cleaving activity. However, when the SOD was digested with proteases, its activity to cleave supercoiled DNA was completely abolished. These results suggested that the supercoiled DNA-cleaving activity was relative to the apoenzyme moiety, less relevant to the O2- dismutation site of SOD. The enzymatic mechanism of cleaving activity of SOD to supercoiled DNA was discussed.

A study of retentive filler and its use in dentistry

OBJECTIVE

The purpose of this study was to develop a fine compound inorganic filler with special surface microstructure (called retentive filler or RF) and to investigate its use in composite resin and synthetic resin teeth.

METHODS

Barium silicate glass and fine silicon dioxide or barium silicate glass were mixed and sintered, then dispersed and classified by sedimentation. The surface microstructure and the particle size distribution of retentive filler were surveyed, and the mechanical properties of the composite resin and the resin tooth material reinforced with RF were tested.

RESULTS

Scanning electron microscopy showed that the surface of RF particles is distinguished for its retentive contour microstructure. The particle size of RF is smaller than 3 microns. The mechanical properties of composite resin reinforced with RF are better than that of composites containing normal fillers, and the wear resistance of the resin tooth material containing RF is better than that of normal synthetic resin.

CONCLUSIONS

The RF can be successfully prepared by the technological process in this study. Because of the special surface microstructure, RF has a good bonding to the resin matrix. The testing results suggest that it is feasible to improve the mechanical properties, especially the wear resistance of the composite resin and resin teeth, by using retentive filler.