Kinetic mechanism of GTP binding and RNA synthesis during transcription initiation by bacteriophage T7 RNA polymerase

We have used stopped-flow and rapid chemical quench-flow methods to investigate the kinetics of the early steps during transcription initiation by bacteriophage T7 RNA polymerase. Most promoters of T7 RNA polymerase initiate with two GTPs. The kinetics of GTP binding was investigated by monitoring the fluorescence changes resulting from GTP binding to polymerase and fluorescent 2-aminopurine-containing promoter DNA complex. Scheme 1 was determined from studies of T7 Phi10 promoter at 25 degrees C, where (E.D)n represents the polymerase.DNA complex in different conformations. GTPE and GTPI represent the elongating and initiating GTP molecules incorporated at the +2 and +1 positions, respectively. Our studies show that GTP at the elongation site binds with at least 10-fold tighter affinity than the GTP at the initiation site. Two conformational changes were revealed upon GTP binding to the polymerase.2-aminopurine DNA complex. The first conformational change occurred upon GTP binding to the elongation site. This conformational change was reversible, and studies with partially melted DNA and incorrect NTPs suggested that it may represent a DNA melting and/or base pairing step. A second rate-limiting conformational change whose rate was same as the maximum rate of pppGpG synthesis occurred after two GTPs were bound. As with DNA polymerases, this rate-limiting conformational change probably occurs at each NMP incorporation event and may be involved in proper positioning of the initiation and the elongating GTPs within the polymerase active site to achieve efficient and accurate RNA synthesis.

Fluorescence and photobleaching dynamics of single light-harvesting complexes

Single light-harvesting complexes LH-2 from Rhodopseudomonas acidophila were immobilized on various charged surfaces under physiological conditions. Polarized light experiments showed that the complexes were situated on the surface as nearly upright cylinders. Their fluorescence lifetimes and photobleaching properties were obtained by using a confocal fluorescence microscope with picosecond time resolution. Initially all molecules fluoresced with a lifetime of 1 +/- 0.2 ns, similar to the bulk value. The photobleaching of one bacteriochlorophyll molecule from the 18-member assembly caused the fluorescence to switch off completely, because of trapping of the mobile excitations by energy transfer. This process was linear in light intensity. On continued irradiation the fluorescence often reappeared, but all molecules did not show the same behavior. Some LH-2 complexes displayed a variation of their quantum yields that was attributed to photoinduced confinement of the excited states and thereby a diminution of the superradiance. Others showed much shorter lifetimes caused by excitation energy traps that are only approximately 3% efficient. On repeated excitation some molecules entered a noisy state where the fluorescence switched on and off with a correlation time of approximately 0.1 s. About 490 molecules were examined.

Disease-associated mutations in cytoplasmic loops 1 and 2 of cystic fibrosis transmembrane conductance regulator impede processing or opening of the channel

Since little is known about the contribution to function of the N-terminal cytoplasmic loops (CL1, residues 139-194; CL2, residues 242-307) of cystic fibrosis transmembrane conductance regulator (CFTR), all nine point mutations identified in CLs 1 and 2 from patients with cystic fibrosis were reconstructed in the expression vector pcDNA3-CFTR and expressed transiently in COS-1 and HEK-293 cells and stably in Chinese hamster ovary (CHO) cells. Four amino acid substitutions retarded production of mature, fully glycosylated CFTR, suggesting that misprocessing of the channel causes the disease symptoms in the affected patients. Protein maturation could not be promoted by cell culture conditions of reduced temperature (26 degrees C). When properly processed mutants were evaluated for functional defects by the iodide efflux method, the G178R- and E193K-CFTR-expressing cell lines showed impaired anion translocation activities. Patch-clamp studies of single channels revealed that E193K variants had a significantly decreased open probability, which resulted from an increase in the mean closed time of the channels. This contrasted with a previous study of disease-associated point mutations in CL3 that mainly affected the mean open time. None of the maturation-competent CL 1 and 2 mutants had altered conductance. Thus, the N-terminal CLs appear not to contribute to the anion translocation pathway of CFTR; rather, mutations in CL1 can impede transition to the open state. Interestingly, the ability of the non-hydrolyzable ATP analogue adenylyl imidodiphosphate (AMP-PNP) to lock the channel into open bursts was abolished by the I148T and G178R amino acid substitutions.

Nonexponential kinetics of a single tRNAPhe molecule under physiological conditions

The fluorescence decay functions of individual, specifically labeled tRNAPhe molecules exhibit nonexponential character as a result of conformational dynamics occurring during the measurement on a single molecule. tRNAPhe conformational states that interchange much more slowly are evidenced by the distribution of lifetimes observed for many individual molecules. A structural model for the nonexponential decay indicates that the tRNAPhe-probe adduct fluctuates between two states, one of which provides conditions that quench the probe fluorescence.

The C. elegans gene pag-3 is homologous to the zinc finger proto-oncogene gfi-1

Mutations in the Caenorhabditis elegans gene pag-3 result in misexpression of touch receptor-specific genes in the BDU interneurons and in motility defects. We cloned pag-3 and found that the gene encodes a C2H2-type zinc finger protein related to the mammalian GFI-1 protein. Sequencing of the three pag-3 alleles showed that two apparent null alleles encode a nonsense mutation before the zinc fingers and a missense mutation in the fourth zinc finger that changes a coordinating histidine to a tyrosine. The third allele contains a nonsense mutation in the N-terminal region but is not a null allele. Northern analysis showed that a single pag-3 transcript of about 1.6 kb is present in embryos and L1, L2 and L3 larvae. pag-3 message levels were about twofold higher in pag-3 mutants than in wild-type animals, which suggested that pag-3 may negatively regulate its own expression. pag-3lacZ fusion genes were expressed in the BDU interneurons, the touch neurons, 11 VA and 11 VB ventral cord motor neurons, two AVF interneurons and in unidentified neurons of the retrovesicular ganglion. The BDU neurons and the ALM touch neurons are lineal sister cells in the AB.a lineage and the VA and VB motor neurons are lineal sister cells in the AB.p lineage. The VA motor neurons are required for backward movement and the VB motor neurons are required for forward movement. Mosaic analysis showed that the wild-type pag-3 gene is required in the AB.p lineage for coordinated movement and in the AB.a lineage to suppress touch neuron gene expression in the BDU neurons. Because pag-3 is expressed in both the BDU neurons and in the touch neurons, another protein(s) not expressed in the touch neurons may interact with pag-3 to repress touch neuron gene expression in the BDU neurons. Alternatively, another protein in the touch receptor cells may inactivate PAG-3 and allow expression of the touch receptor program. These results show that pag-3 is a temporally regulated gene that is expressed early in development and functions in multiple types of neurons. They also strongly suggest that the PAG3 protein is a DNA-binding protein with properties similar to the mammalian proto-oncogene product GFI-1.

Kinetic mechanism of transcription initiation by bacteriophage T7 RNA polymerase

The kinetic mechanism of transcription initiation by bacteriophage T7 RNA polymerase was investigated using transient state kinetic methods. Transcription by bacteriophage T7 RNA polymerase occurs in three stages consisting of initiation, promoter clearance, and elongation. Abortive products, up to 6-8-mer, were synthesized during the initiation phase; the transition from initiation to elongation occurred between the synthesis of 6-8-mer and 11-12-mer, and the processive elongation phase began after the synthesis of 12-mer RNA. Our results show that the synthesis of elongation product from the phi 10 promoter is limited both by the efficiency of initiation and by the frequency at which the polymerase escapes the promoter. Studies with heparin trap suggest that the polymerase maintains contact with the promoter region during multiple turnovers of abortive RNA synthesis; thus, the polymerase does not completely dissociate from the promoter after each event of abortive RNA synthesis. The pre-steady-state kinetics of RNA synthesis indicate that initiation occurs at a rate constant (3.5 s(-1)) that is about 30 times faster than the steady-state rate constant of RNA synthesis (0.1 s(-1)). The steady-state rate constant of RNA synthesis is limited largely by the cycling of the RNA polymerase, whereas initiation is limited by the formation of pppGpG, the first RNA product. We show that the synthesis of pppGpG is not limited by steps associated with GTP binding, DNA binding, or the melting of the promoter DNA. Instead, the kinetic results indicate that initiation at the phi10 promoter is limited either by the first phosphodiester bond formation step or more likely by a conformational change prior to pppGpG formation. Such a conformational change could play a role in proper alignment of the initiating and elongating NTPs for efficient phosphodiester bond formation and in maintaining the fidelity of RNA synthesis.

[Immunohistochemical study on the distribution and coexistence of SP, VIP and NPY in the rat submandibular gland]

The distribution and coexistence of SP, VIP and NPY in the submandibur gland of rat have been studied with immunohistochemical ABC methods. The results indicated that SP, VIP and NPY-IR nerve fibers were presented as varicose and linear profiles, which mainly travelled around acini, duct and blood vessels. The ganglion cells in submandibular gland showed SP, VIP and NPY-IR all positive immunocytochemically. The findings indicated that the neuropeptides were coexisted in the same neuron body and might play the role of regulation of the secretary activity and effective blood supply.

A basic helix-loop-helix-leucine zipper transcription complex in yeast functions in a signaling pathway from mitochondria to the nucleus

The expression of some nuclear genes in Saccharomyces cerevisiae, such as the CIT2 gene, which encodes a glyoxylate cycle isoform of citrate synthase, is responsive to the functional state of mitochondria. Previous studies identified a basic helix-loop-helix-leucine zipper (bHLH/Zip) transcription factor encoded by the RTG1 gene that is required for both basal expression of the CIT2 gene and its increased expression in respiratory-deficient cells. Here, we describe the cloning and characterization of RTG3, a gene encoding a 54-kDa bHLH/Zip protein that is also required for CIT2 expression. Rtg3p binds together with Rtg1p to two identical sites oriented as inverted repeats 28 bp apart in a regulatory upstream activation sequence element (UASr) in the CIT2 promoter. The core binding site for the Rtg1p-Rtg3p heterodimer is 5'-GGTCAC-3', which differs from the canonical E-box site, CANNTG, to which most other bHLH proteins bind. We demonstrate that both of the Rtg1p-Rtg3p binding sites in the UAS(r) element are required in vivo and act synergistically for CIT2 expression. The basic region of Rtg3p conforms well to the basic region of most bHLH proteins, whereas the basic region of Rtg1p does not. These findings suggest that the Rtg1p-Rtg3p complex interacts in a novel way with its DNA target sites.

Phosphorylation by protein kinase C is required for acute activation of cystic fibrosis transmembrane conductance regulator by protein kinase A

Protein kinase A (PKA) stimulates Cl secretion by activating the cystic fibrosis transmembrane conductance regulator (CFTR), a tightly regulated Cl- channel in the apical membrane of many secretory epithelia. The CFTR channel is also modulated by protein kinase C (PKC), but the regulatory mechanisms are poorly understood. Here we present evidence that PKA-mediated phosphorylation alone is not a sufficient stimulus to open the CFTR chloride channel in the presence of MgATP; constitutive PKC phosphorylation is essential for acute activation of CFTR by PKA. When patches were excised from transfected Chinese hamster ovary cells, CFTR responses to PKA became progressively smaller with time and eventually disappeared. This decline in PKA responsiveness did not occur in the presence of exogenous PKC and was reversed by the addition of PKC to channels that had become refractory to PKA. PKC enhanced PKA stimulation of open probability without increasing the number of functional channels. Short-term pretreatment of cells with the PKC inhibitor chelerythrine (1 microM) reduced the channel activity that could be elicited by forskolin in cell-attached patches. Moreover, in whole cell patches, acute stimulation of CFTR currents by chlorophenylthio-cAMP was abolished by two chemically unrelated PKC inhibitors, although an abrupt, partial activation was observed after a delay of >15 min. Modulation by PKC was most pronounced when basal PKC phosphorylation was reduced by briefly preincubating cells with chelerythrine. Constitutive PKC phosphorylation in unstimulated cells permits the maximum elevation of open probability by PKA to reach a level that is approximately 60% of that attained during in vitro exposure to both kinases. Differences in basal PKC activity may contribute to the variable cAMP responsiveness of CFTR channels in different cell types.

Alleles of Pto and Fen occur in bacterial speck-susceptible and fenthion-insensitive tomato cultivars and encode active protein kinases

The Pto gene was derived originally from the wild tomato species Lycopersicon pimpinellifolium and confers resistance to Pseudomonas syringae pv tomato strains expressing the avirulence gene avrPto. The Fen gene is also derived from L. pimpinellifolium and confers sensitivity to the insecticide fenthion. We have now isolated and characterized the alleles of Pto and Fen from cultivated tomato, L. esculentum, and designated them pto and fen. High conservation of genome organization between the two tomato species allowed us to identify the pto and fen alleles from among the cluster of closely related Pto gene family members. The pto and fen alleles are transcribed and have uninterrupted open reading frames that code for predicted proteins that are 87 and 98% identical to the Pto and Fen protein kinases, respectively. In vitro autophosphorylation assays revealed that both the pto and fen alleles encode active kinases. In addition, the pto kinase phosphorylates a previously characterized substrate of Pto, the Pto-interacting Pti1 serine/threonine kinase. However, the pto kinase shows impaired interaction with Pti1 and with several previously isolated Pto-interacting proteins in the yeast two-hybrid system. The observation that pto and fen are active kinases and yet do not confer bacterial speck resistance or fenthion sensitivity suggests that the amino acid substitutions distinguishing them from Pto and Fen may interfere with recognition of the corresponding signal molecule or with protein-protein interactions involved in the Pto- and Fen-mediated signal transduction pathways.

Initiation of Plant Disease Resistance by Physical Interaction of AvrPto and Pto Kinase

Resistance to bacterial speck disease in tomato occurs when the Pto kinase in the plant responds to expression of the avirulence gene avrPto in the Pseudomonas pathogen. Transient expression of an avrPto transgene in plant cells containing Pto elicited a defense response. In the yeast two-hybrid system, the Pto kinase physically interacted with AvrPto. Alterations of AvrPto or Pto that disrupted the interaction in yeast also abolished disease resistance in plants. The physical interaction of AvrPto and Pto provides an explanation of gene-for-gene specificity in bacterial speck disease resistance.

Equilibrium and stopped-flow kinetic studies of interaction between T7 RNA polymerase and its promoters measured by protein and 2-aminopurine fluorescence changes

The mechanism of bacteriophage T7 RNA polymerase binding to its promoter DNA was investigated using stopped-flow and equilibrium methods. To measure the kinetics of protein-DNA interactions in real time, changes in tryptophan fluorescence in the polymerase and 2-aminopurine (2-AP) fluorescence in the promoter DNA upon binary complex formation were used as probes. The protein fluorescence changes measured conformational changes in the polymerase whereas the fluorescence changes of 2-AP base, substituted in place of dA in the initiation region (-4 to +4), measured structural changes in the promoter DNA, such as DNA melting. The kinetic studies, carried out in the absence of the initiating nucleotide, are consistent with a two-step DNA binding mechanism, [formula: see text] where the RNA polymerase forms an initial weak EDa complex rapidly with an equilibrium association constant K1. The EDa complex then undergoes a conformational change to EDb, wherein RNA polymerase is specifically and tightly bound to the promoter DNA. Both the polymerase and the promoter DNA may undergo structural changes during this isomerization step. The isomerization of EDa to EDb is a fast step relative to the rate of transcription initiation and its rate does not limit transcription initiation. To understand how T7 RNA polymerase modulates its transcriptional efficiency at various promoters at the level of DNA binding, comparative studies with two natural T7 promoters, Phi10 and Phi3.8, were conducted. The results indicate that kinetics, the bimolecular rate constant of DNA binding, kon (K1k2), and the dissociation rate constant, koff (k-2), and thermodynamics, the equilibrium constants of the two steps (K1 and k2/k-2) both play a role in modulating the transcriptional efficiency at the level of DNA binding. Thus, the 2-fold lower kon, the 4-fold higher koff, and the 2-5-fold weaker equilibrium interactions together make Phi3.8 a weaker promoter relative to Phi10.

[Factors affecting survival of hepatic carcinoma patients and their clinical significance]

621 patients with unresectable hepatocellular carcinoma were given more than 2 times of intervention treatment. The correlations between the survival rates, tumor histology, portal tumor thrombus and the method and frequency of intervention treatment were analyzed.

RESULTS

(1) The survival rates were higher in cases with single nodular tumor than in those with diffuse-tumors. (2) The survival rates of cases without tumor thrombus in portal system were significantly higher than those with tumor thrombus. However, no correlation was found between the survival rates and the location of thrombus in portal vein. (3) Intraarterial drug infusion combined with lipoidol plus gelatin sponge embolization gave the best therapeutic resalts. (4) How frequent was the intervention would be determined by the patients' general condition and was dependent on the quality of treatment. The cumulative survival rates were greatly affected by the above-mentioned factors. The treatment needs to be individualized.

Holographic digital data storage in a photorefractive polymer

We report high-contrast storage of 64-kbit digital data pages in a photorefractive polymer material. Singlepage writing, reading, and erasing operations were demonstrated with a dual-function-dopant polymeric material having a dark lifetime of several days. Data were reconstructed without error by use of several simple readout algorithms.

[The technique for extracting liposoluble components of Salvia miltiorrniza]

To investigate a reasonable producting technique for extracting the liposoluble components of Salvia miltiorrhiza, we made an orthogonal test on percolate technique of tanshinones. The results show that the concentration of alcohol has a highly remarkable influence on the extracting ratio of extract and tanshinones, where 65% alcohol is much better than higher concentration alcohol in percolate technique of tanshinones. This new technique can be employed to reduce sharply the cost and increase the extracting ratio.

Endogenous nitric oxide contributes to strain-related differences in airway responsiveness in rats

The effects of N(omega-nitro-L-arginine (L-NNA), a nitric oxide synthase inhibitor, on airway responsiveness were studied in the spontaneously hyperresponsive Fischer and the control normoresponsive Lewis rat strains to investigate the role of the endogenous nitric oxide (NO) pathway in strain-related differences in airway responsiveness. Responsiveness to inhaled methacholine was significantly increased in L-NNA-treated Lewis rats but not in Fischer rats. L-NNA increased carbachol-induced tracheal contractions in vitro to a larger extent in Lewis rats compared with Fischer rats. The effect of L-NNA was abolished by removal of the epithelium. Carbachol induced a NO-dependent increase in guanosine 3',5'-cyclic monophosphate levels in tracheal tissues but to a lesser extent in Fischer (2.1-fold increase) than in Lewis (3.7-fold increase) rats. In conclusion, endogenous NO is involved in the regulation of airway responsiveness to cholinergic agonists in rats. A relatively ineffective NO-guanosine 3',5'-cyclic monophosphate regulatory mechanism in Fischer rats contributes, in part, to strain-related differences in airway responsiveness between Fischer and Lewis rats.

pag-3, a Caenorhabditis elegans gene involved in touch neuron gene expression and coordinated movement

Mutations in a newly identified gene, pag-3, cause ectopic expression of touch neuron genes meo-7, mec-7lacZ and mec-4lacZ in the lineal sisters of the ALM touch neurons, the BDU neurons. Pag-3 mutants also show a reverse kinker uncoordinated phenotype. The first pag-3 allele was isolated in a screen for mutants with altered immunofluorescence staining patterns. Two additional pag-3 alleles were identified in a noncomplementation screen of 38,000 haploid genomes. All of the pag-3 alleles were recessive to wild type and cause the same phenotypes. Two-factor crosses, deficiency mapping and three-factor crosses located pag-3 to the right arm of the X chromosome between unc-3 and unc-7. Because recessive mutations in pag-3 result in expression of several touch cell specific genes in the BDU neurons, pag-3(+) must directly or indirectly suppress expression of these genes in the BDU neurons. Although pag-3 mutants did not show mec-3lacZ expression in their BDU neurons, expression of mec-7lacZ and mec-4lacZ in the BDU neurons of pag-3 mutants required mec-3(+).

[Determination of panaxadiol and panaxatriol in shihu yeguang pills]

The contents of panaxadiol and panaxatriol in Shihu Yeguang Pills manufactured by pharmaceutical works in Beijing, Jinan, Guangzhou and other places were determined by TLC-densitometry. A quantitative method has been developed to serve as a reference to quality control of these pills.

A C. elegans mutant screen based on antibody or histochemical staining

A method has been developed for isolating mutations in Caenorhabditis elegans that alter antibody or histochemical staining patterns. The basis for this method is a new procedure for making C. elegans permeable that does not kill the eggs contained within the uterus of gravid adult hermaphrodites. A mutagenized population of gravid hermaphrodites is made permeable and then stained with either an antibody or a histochemical stain. Animals that stain aberrantly are picked to individual petri plates and the eggs within the uterus of the stained mother hatch and establish a new genetic line. Antibody and histochemical stains are especially useful phenotypes because the staining pattern will usually directly reflect the gene expression pattern of the gene that codes for the antigen or enzyme. This method was used to isolate mutants that alter the expression of a mec-7lacZ fusion gene. Transgenic animals that contained the mec-7lacZ gene integrated into chromosome I were treated with the mutagen ethylmethanesulfonate, allowed to self-fertilize for two generations and then stained with X-gal or antibodies against beta-galactosidase. Gravid animals that stained abnormally were picked to fresh petri plates and their offspring were used to establish new mutant lines.

[The early treatment of unilateral crossbite]

Fifteen unilateral crossbite patients of primary and mixed dentition with mandibular asymmetry were treated by transverse expansion using removable appliance. Posteroanterior cephalometric analysis was utilized before and after treatment. The results suggested that after the correction of unilateral crossbite, the deviation of midsagittal mandibular total lenth decreased significantly. According to this study, early treatment of unilateral crossbite is indicated.

Airways of a hyperresponsive rat strain show decreased relaxant responses to sodium nitroprusside

The aim of the current studies was to investigate the possibility that a decreased relaxant response to nitric oxide (NO) might contribute to strain-related differences in airway responsiveness in the rat. Isolated tracheal rings from hyperresponsive. Fisher rats were confirmed to be more responsive to carbachol [mean effective concentration (EC50) = 2.45 x 10(-7) M] than those from Lewis (EC50 = 3.60 x 10(-7) M, P < 0.03) and ACI (EC50 = 3.85 x 10(-7) M, P < 0.01) rats. Sodium nitroprusside (SNP), a NO donor, caused relaxation of the carbachol (10(-6) M) contracted tracheal rings, but the half-maximal inhibition concentration (IC50) SNP in Fisher rats (5.60 x 10(-6) M) was significantly higher than in Lewis (1.34 x 10(-6) M, P < 0.001) and ACI rats (1.13 x 10(-6) M, P < 0.0005). The inhibitory effect of SNP on airway responsiveness to inhaled methacholine (MCh) in vivo was also less pronounced for Fisher than Lewis rats. SNP induced an accumulation of guanosine 3',5'-cyclic monophosphate (cGMP) in cultured tracheal smooth muscle cells (TSM). Fisher TSM produced less cGMP on exposure to SNP compared with TSM from ACI (P < 0.01) and Lewis (P < 0.0001) rats. A decreased guanylyl cyclase activity may account for the impaired relaxant effect of SNP in Fisher rats.

[Adoptive immunotherapy of malignant pleural effusion with TIL/rIL2 (tumor-infiltrating lymphocytes/recombinant interleukin 2)]

TIL of 24 patients with malignant pleural effusions were induced and expanded in vitro. The phenotype of lymphocytes IL2R, NK cytotoxicity activity were analysed in fresh and activated TIL. CEA and cytology of malignant pleural effusion were detected before and after treatment with TIL/rIL2. The results indicated: CD4.CD8.IL2R, NK activity increased markedly, CEA level decreased in all of the patients, tumor cells disappeared in some patients. The pleural effusion disappeared in 63%. The total effective rate of the treatment is 79%. No serious toxicity and side effects were found in 1 to 6 months period of following-up after treatment.

Energy transfer and trapping in photosystem I reaction centers from cyanobacteria

A mutant strain of the cyanobacterium Synechocystis 6803, TolE4B, was constructed by genetic deletion of the protein that links phycobilisomes to thylakoid membranes and of the CP43 and CP47 proteins of photosystem II (PSII), leaving the photosystem I (PSI) center as the sole chromophore in the photosynthetic membranes. Both intact membrane and detergent-isolated samples of PSI were characterized by time-resolved and steady-state fluorescence methods. A decay component of approximately 25 ps dominates (99% of the amplitude) the fluorescence of the membrane sample. This result indicates that an intermediate lifetime is not associated with the intact membrane preparation and the charge separation in PSI is irreversible. The decay time of the detergent-isolated sample is similar. The 600-nm excited steady-state fluorescence spectrum displays a red fluorescence peak at approximately 703 nm at room temperature. The 450-nm excited steady-state fluorescence spectrum is dominated by a single peak around 700 nm without 680-nm "bulk" fluorescence. The experimental results were compared with several computer simulations. Assuming an antenna size of 130 chlorophyll molecules, an apparent charge separation time of approximately 1 ps is estimated. Alternatively, the kinetics could be modeled on the basis of a two-domain antenna for PSI, consistent with the available structural data, each containing approximately 65 chlorophyll a molecules. If excitation can migrate freely within each domain and communication between domains occurs only close to the reaction center, a charge separation time of 3-4 ps is obtained instead.

[Determination of primaquine and hepatic targeting neoglycoalbumin-primaquine in whole blood and liver of mouse by normalphase high-performance liquid chromatography]

We have developed a method to estimate primaquine (PQ) and hepatic targeting antimalarial agent neoglycoalbumin-primaquine (NGA PQ) in whole blood and liver of mice by sensitive and selective high-performance liquid chromatography. The primaquine was extracted out with ether from the basified biological samples in the PQ diphosphate group or from the samples which were acidic hydrolyzed then basified in NGA-PQ group. The extracts were evaporated under N2 then dissolved in the mobile phase. A linear chain analogue of primaquine was used as the internal standard. The samples were injected into the normal phase silica column with chloroform: methanol:ammonia solution (86.8:12.5:0.7,V/V/V) as mobile phase and detected at 254 nm. The average recovery of the method was 100.09 +/- 3.46 (mean +/- s)%; the CV of within-day and between-day were 2.7%-6.13% (n = 5) and 8.32%-13.56% (n = 9) respectively; in PQ group and NGA-PQ group, the PQ concentrations ranged from 10-20,000 ng/ml blood or 1g. liver respectively, and they all yielded a good linear relationship with the peak height ratios. No endogeneous interference was found in chromatograms of biological samples.

Clinical observation on needling extrachannel points in treating mental depression

Totally 20 cases of mental depression were treated by needling extrachannel points with an effective rate of 90%; comparison of these cases with 21 controls treated with amitriptyline, showed no significant difference in effect (P > 0.05). Measured with Hamilton's scale, factors of anxiety somatization, cognitive disturbance, retardation, sleep disturbance and feeling of despair in both the needling and control groups showed obvious decrease in the mean value, and the change in anxiety somatization was markedly significant in the needling group as compared with that in the controls (P < 0.01). Our studies revealed that after 6 weeks of needling the power of slow wave delta decreased while that of the fast wave alpha increased, all significantly different as compared with that before and during the treatment (P < 0.05).

MHC-independent presentation of mycobacteria to human gamma delta T cells

The majority of human peripheral gamma delta T cells express antigen receptors using the V gamma 9 and V delta 2 gene products. Cells of this subset have been previously shown to uniformly recognize mycobacteria regardless of their V-(D)-J junctional sequences in an MHC-unrestricted manner. This reactivity superficially resembles activation of alpha beta cells by bacterial superantigens, which are thought to be presented by monomorphic regions of MHC class II molecules. It is not known whether presentation of the mycobacterial antigen to V gamma 9/V delta 2 T cells is also mediated by class II MHC molecules. In order to examine the similarity between presentation of bacterial superantigens to alpha beta T cells and the presentation of mycobacteria to gamma delta T cells we have studied the role of class II MHC molecules in presentation of the mycobacterial antigen AP-MT to V gamma 9/V delta 2 clones. Activation of gamma delta T cells by AP-MT required direct contact with antigen presenting cells, indicating that an interaction with cell surface molecules on antigen presenting cells is required. Class II MHC molecules were neither sufficient nor necessary for effective presentation of AP-MT to the gamma delta T cells, as transfectants expressing class II MHC molecules were unable to present, whereas cell lines lacking expression of MHC class II molecules could present this mycobacterial antigen.(ABSTRACT TRUNCATED AT 250 WORDS)

Antimicrobial compounds from Petalostemum purpureum

EtOH extracts of Petalostemum purpureum demonstrated antimicrobial activity against bacteria and fungi. Bioassay-directed fractionation led to the isolation of petalostemumol [1] as the active constituent. Its structure was determined by a single crystal X-ray diffraction analysis. A minor component designated petalostemumol G [3] is believed to be an artifact of the isolation procedure. Its structure was confirmed by a single crystal X-ray analysis of its pentamethylether 2. A number of derivatives of 1 and 3, including the Me- and benzylethers and acetates, were prepared.

[Thin layer chromatography for identification of 9 species of traditional Chinese medicine in baihe gujin tang granules]

Baihe Gujin Tang granules are mainly composed of nine species of traditional Chinese medicine and other admixtures, so the composition is very complex. In order to confirm the presence of each traditional Chinese medicine in the preparation, a thin layer chromatographic method was developed successfully for analysis of Scrophulariae, Platycodon, Paeoniae and Glycyrrhizae.

Simulations of the temperature dependence of energy transfer in the PSI core antenna

In order to understand the organization of the PSI core antenna and to interpret results obtained from studies of the temperature and wavelength dependence of energy transfer and trapping in the PSI particles, we have constructed a model for PSI in which spectral heterogeneity is considered via a self-consistent approach based on Forster transport. The temperature dependence of the absorption and emission spectra of the individual Chl molecules in the protein matrix is calculated based on a model Hamiltonian which includes a phonon contribution. Time and wavelength resolved kinetics of PSI at different temperatures are investigated by means of two-dimensional lattice models. We conclude that wavelength-dependent fluorescence decay kinetics result only when two or more bottlenecks exist in the energy transfer and trapping process. A single trap or several pseudo-traps with spectrally identical environments do not lead to wavelength dependent decays. Simple funnel arrangements of the spectral types can be ruled out. At least one pigment with energy lower than the photochemical trap located close to the reaction center is required to produce the trends of the fluorescence lifetimes observed experimentally. The remainder of the core antenna is consistent with a random arrangement of spectral types.

Energy transfer and trapping in the photosystem I core antenna. A temperature study

The fluorescence decay kinetics of the photosystem I-only mutant strain of Chlamydomonas reinhardtii, A4d, are used to study energy transfer and structural organization in photosystem I (PSI). Time-resolved measurements over a wide temperature range (36-295 K) have been made both on cells containing approximately 65 core chl a/P700 and an additional 60-70 chl a + b from LHC proteins and on PSI particles containing 40-50 chl a/P700. In each case, the fluorescence decay kinetics is dominated by a short component, tau 1 which is largely attributed to the lifetime of the excitations in the core complex. The results are discussed in terms of simulations of the temperature dependence of tau 1 in model systems. Spectral inhomogeneity and the temperature dependence of the spectral lineshapes are included explicitly in the simulations. Various kinds of antenna arrangements are modeled with and without the inclusion of pigments with lower absorption energies than the trap (red pigments). We conclude that funnel arrangements are not consistent with our measurements. A random model that includes one or two red pigments placed close to the trap shows temperature and wavelength dependence similar to that observed experimentally. A comparison of the temperature dependence of tau 1 for cells and PSI particles is included.

[Inhibitory effects of the extract of pilose antler on monoamine oxidase in aged mice]

It was demonstrated that the water extract of Pilose Antler (WEPA) showed a higher inhibitory effect on MAO-B activities in the liver and brain tissues of aged mice, but nearly no effect on NAO-A. WEPA could significantly increase the contents of 5-HT, NE and DA in the brain tissues of aged mice. In vitro experiments revealed that the inhibition of WEPA on MAO-B was competitive, but on MAO-A was of mixed-type.

Secondary prevention of myocardial reinfarction with low dose aspirin

A clinical trial of secondary prevention of reinfarction with low dose aspirin is reported. 50 mg aspirin per day was administered in 216 case. 211 cases did not take aspirin or any other antiplatelet agents as a control group. The follow-up periods in the two groups were 19.4 +/- 12.6 mon and 20.7 +/- 13.0 mon, respectively. There were 175 males in the aspirin group and 137 males in the control group. The incidence of reinfarction was reduced by 65% and platelet aggregation was inhibited obviously in the aspirin group as compared to the control group in men, whereas no significant trends were observed in women.

The complete sequence of the unit YCR59, situated between CRY1 and MAT, reveals two long open reading frames, which cover 91% of the 10.1 kb segment

We have entirely sequenced YCR59, which is a 10.1 kb segment of the right arm of chromosome III, and is part of the clone E5F from the Newlon collection. The segment contains two long open reading frames (ORFs): YCR591 which starts in the adjacent fragment H9G (situated towards CRY1 and the centromere), and continues with 1833 codons in YCR59. The second ORFYCR592 is 1226 codons long and encoded entirely within YCR59. The two ORFs represent 91% of the total length of the segment. Excellent agreement in both location and length is found between the ORFs YCR591 and YCR592 and the transcripts 86 and 87 respectively in the Yoshikawa and Isono (1990) map of chromosome III. The two ORFs correspond to new genes and show no significant similarity with any known genes.

Further eudesmane derivatives from verbesina species

The aerial parts of VERBESINA PERSICIFOLIA DC afforded a new eudesmane derivative in addition to known compounds. The roots of V. SUBCORDATA gave also new eudesmane cinnamates in addition to several known ones as well as a 5alpha-hydroxybicyclogermacra-1 (10) E, 4 (15)-diene. A reinvestigation of V. VIRGINICA L. gave two new ( Z)-configurated coumarates. Furthermore the structures of some sesquiterpenes are revised. The structures were elucidated by highfield NMR spectroscopy and a few chemical reactions.

Bisabolone derivatives and sesquiterpene lactones from centaurea species

The investigation of three CENTAUREA species collected in Argentina afforded, in addition to several known sesquiterpene lactones, a new guaianolide, a germacranolide, and two bisabolone derivatives. The structures were elucidated by highfield (1)H-NMR spectroscopy.