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Y P Cai

Publications and source records attributed to Y P Cai.

17 recordsLinked to original sources
PubMed2001

[Selective isolation of anethole from volatile oil of Foeniculum vulgare Mill by inclusion crystalline with chela-shape host].

AIM: To isolate the components from the volatile oil of Foeniculum vulgare Mill. METHODS: According to the function of molecular recognition of supramolecular chemistry, chela shape molecule, trans-1, 2-biphenyl-1, 2-acenaphthendiol was used as host molecule and the volatile oil of Foeniculum vulgare Mill as guest molecule. Trans-1, 2-biphenyl-1, 2-acenaphthendiol can recognize the components that endowed with interactional complementarity and form inclusion compound as crystals. RESULTS: The anethole in the volatile oil was selectively included as trans-1,2-biphenyl-1,2-acenaphthendiol which was obtained in pure state from the inclusion compound by Kugelrohr vacuum technology. The formation of inclusion compound was confirmed by means of IR and powder XRD. The structure of the selectively isolated component was elucidated as trans-anethole by means of IR, 1HMMR and MS. CONCLUSION: The experimental results showed that the method is simple, rapid and selective for isolation anethole from volatile oil of Foeniculum vulgare Mill.

Allylbenzene Derivatives↗
PubMed2000

Characterization of epitopes for virus-neutralizing monoclonal antibodies to Ross River virus E2 using phage-displayed random peptide libraries.

Ross River virus (RRV) is the predominant cause of epidemic polyarthritis in Australia, yet the antigenic determinants are not well defined. We aimed to characterize epitope(s) on RRV-E2 for a panel of monoclonal antibodies (MAbs) that recognize overlapping conformational epitopes on the E2 envelope protein of RRV and that neutralize virus infection of cells in vitro. Phage-displayed random peptide libraries were probed with the MAbs T1E7, NB3C4, and T10C9 using solution-phase and solid-phase biopanning methods. The peptides VSIFPPA and KTAISPT were selected 15 and 6 times, respectively, by all three of the MAbs using solution-phase biopanning. The peptide LRLPPAP was selected 8 times by NB3C4 using solid-phase biopanning; this peptide shares a trio of amino acids with the peptide VSIFPPA. Phage that expressed the peptides VSIFPPA and LRLPPAP were reactive with T1E7 and/or NB3C4, and phage that expressed the peptides VSIFPPA, LRLPPAP, and KTAISPT partially inhibited the reactivity of T1E7 with RRV. The selected peptides resemble regions of RRV-E2 adjacent to sites mutated in neutralization escape variants of RRV derived by culture in the presence of these MAbs (E2 210-219 and 238-245) and an additional region of E2 172-182. Together these sites represent a conformational epitope of E2 that is informative of cellular contact sites on RRV.

Amino Acid Sequence↗
PubMed2000

Tris(2-cyanoethyl)amine.

In the title compound, N(CH(2)CH(2)CN)(3), (I), the three cyanoethyl groups adopt a conformation with the CN groups oriented in the same direction, suggesting the compound may behave as a potential tripodal ligand.

Journal Article↗
PubMed1999

Multiple alignment and sorting of peptides derived from phage-displayed random peptide libraries with polyclonal sera allows discrimination of relevant phagotopes.

Biopanning of phage-displayed random peptide libraries is a powerful technique for identifying peptides that mimic epitopes (mimotopes) for monoclonal antibodies (mAbs). However, peptides derived using polyclonal antisera may represent epitopes for a diverse range of antibodies. Hence following screening of phage libraries with polyclonal antisera, including autoimmune disease sera, a procedure is required to distinguish relevant from irrelevant phagotopes. We therefore applied the multiple sequence alignment algorithm PILEUP together with a matrix for scoring amino acid substitutions based on physicochemical properties to generate guide trees depicting relatedness of selected peptides. A random heptapeptide library was biopanned nine times using no selecting antibodies, immunoglobulin G (IgG) from sera of subjects with autoimmune diseases (primary biliary cirrhosis (PBC) and type 1 diabetes) and three murine ascites fluids that contained mAbs to overlapping epitope(s) on the Ross River Virus envelope protein 2. Peptides randomly sampled from the library were distributed throughout the guide tree of the total set of peptides whilst many of the peptides derived in the absence of selecting antibody aligned to a single cluster. Moreover peptides selected by different sources of IgG aligned to separate clusters, each with a different amino acid motif. These alignments were validated by testing all of the 53 phagotopes derived using IgG from PBC sera for reactivity by capture ELISA with antibodies affinity purified on the E2 subunit of the pyruvate dehydrogenase complex (PDC-E2), the major autoantigen in PBC: only those phagotopes that aligned to PBC-associated clusters were reactive. Hence the multiple sequence alignment procedure discriminates relevant from irrelevant phagotopes and thus a major difficulty with biopanning phage-displayed random peptide libraries with polyclonal antibodies is surmounted.

Algorithms↗
PubMed1997

[Effect of norepinephrine on the thermosensitive neurons in preoptic area of hypothalamus tissue slices in cold acclimatized rats].

In this work, single unit firing activities were recorded in the preoptic anterior hypothalamus (POAH) brain slices of cold acclimatized and room-temperature housed rats (CR and RR) and the effects of NE on the neuronal discharges were observed. The neurons of POAH in CR became much more sensitive to NE than that in RR (the threshold concentration of NE of CR became significantly lowered). In comparison with RR, the percentage of warm sensitive neurons that could be excited by NE was decreased and some of them even showed inhibitory responses. On the other hand, the percentage of cold sensitive neurons that could be inhibited by NE was decreased and some of them even showed excitatory responses. The percentage of thermo-insensitive neurons that could be either excited or inhibited by NE were increased.

Acclimatization↗
PubMed1996

[Adaptive changes of preoptic thermosensitive neurons in hypothalamic tissue slices of rats after long-term exposure to cold environmental temperature].

In the present work, thermosensitivity and spontaneous firing rate of 86 preoptic neurons in hypothalamic tissue slices from 20 cold acclimated rats (CR, at 5 +/- 1 degrees C for more than 3 weeks) and 127 neurons from 35 warm acclimated rats (WR, at 20 +/- 3 degrees C for the same period) were recorded and compared. The results showed that: (1) The percentage of cold-sensitive neurons in CR were higher than that in WR, the critical temperature and the lowest temperature of the spontaneous firing activity of cold-sensitive neurons in CR were also lower than that in WR. (2) Thermosensitivity and critical temperature of the warm-sensitive neurons in CR were remarkably decreased, and spontaneous firing rate under 37 degrees C was increased. (3) Spontaneous firing rate (37 degrees C) of temperature insensitive neurons in CR were conspicuously increased and the lowest temperature extended downward. These profound changes in response to long-term cold exposure suggested that plasticity of preoptic neurons was involved in the thermoregulation in cold adaptation.

Adaptation, Physiological↗
PubMed1995

[Modulation of norepinephrinergic control of hypothalamus preoptic areas on hibernation bouts in ground squirrels (Citellus dauricus)].

In our previous work, it was shown that hibernation could be enhanced by injection of 6-hydroxydopamine (6-OHDA, 200 micrograms) into the lateral cerebral ventricle of ground squirrels by destructing norepinephrine (NE) nerve terminals in brain areas including hypothalamus, cerebral cortex, hippocampus and periaqueductal gray matter of middle brain. In order to identify the specific area contributing for the modulation of NE system on hibernation, small doses of 6-OHDA (4 micrograms) were microinjected bilaterally into medial preoptic hypothalamus (MPA), lateral preoptic hypothalamus (LPA) and ventromedial hypothalamic nucleus (VMH). The results showed: (1) Depletion of NE on MPA may facilitate hibernation. (2) Little effect was seen by microinjection of 6-OHDA into LPA. (3) The effect of 6-OHDA on VMH was similar to that on MPA, through the mechanism remains to be investigated.

Animals↗
PubMed1995

[Changes of opioid contents in brain and plasma through the hibernation bout cycle of ground squirrels-].

Measurements of beta-endorphin (beta-EP) and Met-enkephalin (MEK) contents in various brain areas and plasma of ground squirrels were carried out by radioimmunoassay (RIA) through euthermia, entrance, deep hibernation and arousal phases of natural hibernation bout. The main results showed that, the beta-EP content in hypothalamus and pituitary during the entrance phase were increased and further deepened during deep hibernation, whereas in hippocampus and plasma the tendency of the changes of beta-EP content took place in an opposite direction, i.e. being lowered down from the euthermia level upon entering the entrance and deep hibernation phase. The content in pons and medulla showed little change through the bout. The contents of MEK were increased during entrance and lowered when entering into deep hibernation to different extent in different brain areas, being most significant change has taken place in hippocampus. These results indicated that the role of beta-EP and MEK in hibernation was different both in regard to brain regional changes of their content and in the degree of the changes.

Animals↗
PubMed1993

Arousal following intra-preoptic area administration of naltrexone, ICI 174864 or nor-BNI in hibernating ground squirrels.

Experiments were performed from January 1 to 30 January, 1989. Drugs were administered to the preoptic area of hibernating ground squirrels through a chronically implanted cannula on the 2nd day of a torpor bout. When naltrexone (an antagonist of opioid receptor) was injected, part (naltrexone, 0.5 or 1 microgram/microliter/32 min) or all (naltrexone, 2 micrograms/microliters/32 min) of the animals' body temperature was increased and they aroused from hibernation within 20 h after the injection. Further experiments showed that intra-preoptic area perfusion of 1 nmol of ICI 174864 (an antagonist of delta receptor) or nor-BNI (an antagonist of kappa receptor), but not beta-FNA (an antagonist of mu receptor), were able to increase the body temperature of hibernating ground squirrels and arouse them from hibernation in 20 h after the injection. These results indicate that (1) opioid peptides in the preoptic area may be involved in the mechanisms of hibernation; (2) activation of delta and kappa receptors in the preoptic area is indispensable for the maintenance of hibernation in ground squirrels.

Animals↗
PubMed1993

Effects of opioid receptors antagonists administration to suprachiasmatic nucleus on hibernation of ground squirrels Citellus dauricus.

1. Drugs were administered to a suprachiasmatic nucleus through a chronically implanted cannula at the second day of a torpor bout of hibernating ground squirrels. After naltrexone injection, the body temperature of the hibernating animals increased and they aroused from hibernation within 20 hr after the injection. 2. Further experiments show that intra-suprachiasmatic nucleus perfusion of 1 nmol of ICI 174864 or nor-BNI, not beta-FNA, were able to increase the body temperature of hibernating ground squirrels and aroused them from hibernation within 20 hr after the injection.

Animals↗
PubMed1992

[Effect of intraventricular injection of 6-hydroxydopamine on the initiation of hibernation in ground squirrels].

The effect of forced depletion of brain norepinephrine (NE) on the onset of hibernation was observed in the ground squirrel (Citellus dauricus) by intraventricular injection of 6-hydroxydopamine (6-OHDA). The results showed: (1) Intraventricular injection of 100-200 micrograms 6-OHDA, which depleted 50-60% NE, markedly facilitated the onset of hibernation, i.e. the average induction period for hibernation in the treated animals was significantly shorter than that of the natural hibernating animals. (2) The average total torpor time in the treated animals was longer than that of natural hibernating animals. (3) All hibernating animals treated with 6-OHDA were able to wake up from deep hibernation spontaneously and undergo normal hibernation bouts. The results indicate the decrease of NE system activity in brain is one important factor in triggering the onset of hibernation.

Animals↗
PubMed1991

Calcium-dependent protease of the cyanobacterium Anabaena: molecular cloning and expression of the gene in Escherichia coli, sequencing and site-directed mutagenesis.

It has been suggested that a calcium-dependent intracellular protease of the cyanobacterium, Anabaena sp., participates in the differentiation of heterocysts, cells that are specialized for fixation of N2. Clones of the structural gene (designated prcA) for this protease from Anabaena variabilis strain ATCC 29413 and Anabaena sp. strain PCC 7120 were identified via their expression in Escherichia coli. The prcA gene from A. variabilis was sequenced. The genes of both strains, mutated by insertion of a drug resistance cassette, were returned to these same strains of Anabaena on suicide plasmids. The method of sacB-mediated positive selection for double recombinants was used to achieve replacement of the wild-type prcA genes by the mutated forms. The resulting mutants, which lacked Ca2(+)-dependent protease activity, were not impaired in heterocyst formation and grew on N2 as sole nitrogen source.

Amino Acid Sequence↗
PubMed1990

Use of a conditionally lethal gene in Anabaena sp. strain PCC 7120 to select for double recombinants and to entrap insertion sequences.

Use of the sacB gene (J. L. Ried and A. Collmer, Gene 57:239-246, 1987) provides a simple, effective, positive selection for double recombinants in Anabaena sp. strain PCC 7120, a filamentous cyanobacterium. This gene, which encodes the secretory levansucrase of Bacillus subtilis, was inserted into the vector portion of a suicide plasmid bearing a mutant version of a chromosomal gene. Cells of colonies in which such a plasmid had integrated into the Anabaena chromosome through single recombination were plated on solid medium containing 5% sucrose. Under this condition, the presence of the sacB gene is lethal. A small fraction of the cells from initially sucrose-sensitive colonies became sucrose resistant; the majority of these sucrose-resistant derivatives had undergone a second recombinational event in which the sacB-containing vector had been lost and the wild-type form of the chromosomal gene had been replaced by the mutant form. By the use of this technique, we mutated two selected genes in the chromosome of Anabaena sp. strain PCC 7120. The conditionally lethal nature of the sacB gene was also used to detect insertion sequences from this Anabaena strain. Sucrose-resistant colonies derived from cells bearing a sacB-containing autonomously replicating plasmid were analyzed. Five different, presumed insertion sequences were found to have inserted into the sacB gene of the plasmids in these colonies. One of them, denoted IS892, was characterized by physical mapping. It is 1.7 kilobases in size and is present in at least five copies in the genome of Anabaena sp. strain PCC 7120.

Cyanobacteria↗