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Biomedical subjects

Y Cui

Publications and source records attributed to Y Cui.

At least 307 records · Page 17Linked to original sources
PubMed1993

Effects of 3,6-dimethamidodibenzopyriodonium citrate on slow inward calcium current in isolated guinea pig ventricular cells.

The effects of 3,6-dimethamidodibenzopyriodonium citrate (I-65) on action potentials and slow inward calcium current (I(si)) were examined on isolated guinea pig ventricular myocardial cells. I-65 (30-100 mumol.L-1) depressed the action potential duration at 20% repolarization (APD20) and, under voltage-clamp conditions, reduced the amplitude of I(si) without changing the I-V relations. I-65 also showed use-dependent effects on I(si). These suggest that I-65 may block I(si) by acting on the inactivated state of Ca channels.

Action Potentials↗
PubMed1993

[Effects of 3,6-dimethylamino-dibenzopyriodonium formiate on action potential and slow inward calcium current in isolated guinea pig ventricular myocytes].

The effects of 3,6-dimethylamino-dibenzopyriodonium formiate (IHC-64) on action potential and slow inward calcium current (I(si)) were investigated in isolated guinea pig ventricular myocytes using whole cell voltage clamp recording. IHC-64 (20 and 200 mumol/L) was shown to markedly decrease APD20 and APD90. However, in the presence of nisoldipine, no obvious effects of IHC-64 on APD20 could be detected. Under voltage clamp conditions, IHC-64 (20 and 200 mumol/L) caused a significant decrease in I(si). The results indicate that IHC-64 can block the calcium channels in isolated guinea pig ventricular myocytes.

Action Potentials↗
PubMed1993

[Studies on insecticidal ingredients from culture supernatant of Bacillus thuringiensis].

Studies on the insecticidal activity of culture supernatant of Bacillus thuringiensis var. kurstaki HD-1, by centrifugation, column chromatography, protein sequence determination, bioassay and other methods. Found that insecticidal activity of culture supernatant appeared on synchronism with cells lysis. Main insecticidal ingredients of culture supernatant is toxin protein of 60 kilodaltons (kDa). Analyse hat purified the toxin protein, we find that its amino acid composition was similar with 135-kDa P1 protein, and its sequence of N-terminal 18 amino acid was same with that of part of the P1 protein. The results presented here provided that the toxin protein was the same source with the P1 protein. Further found that supernatant have synergizing action on the sediment of culture.

Amino Acid Sequence↗
PubMed1992

Retention of C60 and C70 fullerenes on reversed-phase high-performance liquid chromatographic stationary phases.

The separation of C60 and C70 fullerenes on four different polysiloxane stationary phases was examined. It was determined that polar solvents can be used as mobile phases effectively for the separation of fullerene molecules. Unlike previously published work, a polymeric octadecyl siloxane (ODS) stationary phase provided higher separation factors for C70/C60 than did monomeric ODS stationary phases or phenyl substituted stationary phases. For example, for a methanol-diethyl ether (50:50, v/v) mobile phase and C60, k' approximately 5.0 separation factors, alpha = 3.3, were achieved with polymeric ODS compared to alpha = 2.2, with a monomeric ODS stationary phase. A linear solvation energy relationship (LSER) was used to model the importance of solvent interactions and stationary phase interaction to solute retention.

Carbon↗
PubMed1992

Germline variable region gene segment derivation of human monoclonal anti-Rh(D) antibodies. Evidence for affinity maturation by somatic hypermutation and repertoire shift.

To date, there has been no systematic study of the process of affinity maturation of human antibodies. We therefore sequenced the variable region genes (V genes) of 14 human monoclonal antibodies specific for the erythrocyte Rh(D) alloantigen and determined the germline gene segments of origin and extent of somatic hypermutation. These data were correlated with determinations of antibody affinity. The four IgM antibodies (low affinity) appear to be derived from two germline heavy chain variable region gene segments and one or two germline light chain variable region gene segments and were not extensively mutated. The 10 IgG antibodies (higher affinity) appear to be derived from somatic hypermutation of these V gene segments and by use of new V gene segments or V gene segment combinations (repertoire shift). Affinity generally increased with increasing somatic hypermutation; on average, there were 8.9 point mutations in the V gene segments of the four IgM antibodies (Ka = 1-4 x 10(7)/M-1) compared with 19 point mutations in the V gene segments of the 10 IgG antibodies. The four highest affinity antibodies (Ka = 0.9-3 x 10(9)/M-1) averaged 25.5 point mutations. The use of repertoire shift and somatic hypermutation in affinity maturation of human alloantibodies is similar to data obtained in inbred mice immunized with haptens.

Antibodies, Monoclonal↗
PubMed1992

The effect of IH764-3 on fibroblast proliferation and function.

The effect of IH764-3, a potent component isolated from Salvia miltiorrhiza, on the proliferation and function of cultured fibroblasts was studied. It was found that the fibroblast growth curve had a dose-dependent relationship with IH764-3 concentration. The incorporation of 3H-TdR and 3H-proline into fibroblasts was significantly inhibited by IH764-3, and calmodulin, fibronectin and thrombospondin contents in the test group were obviously lower than those in the control group. Flow cytometry showed that in the IH764-3-treated group, the percentage of cells in G0/G1 phase was higher than that in the control. Electron microscopic observation (TEM and SEM) showed that in the treated group, collagen secretion was decreased. All of these results indicate that IH764-3 exerts a direct inhibitory effect on fibroblast proliferation and affects their ability to synthesize collagen.

Animals↗
PubMed1991

State-dependent variation in the inhibitory effect of [D-Ala2, D-Leu5]-enkephalin on hippocampal serotonin release in ground squirrels.

Accumulated evidence has suggested that increased endogenous opioid activities may facilitate the onset of hibernation either directly or possibly through modulation of other neurotransmitter systems. The seasonal change of [D-Ala2, D-Leu5]-enkephalin (DADLE), a delta receptor agonist, in modulating K+ (35 mM)-induced [3H]-5-hydroxytryptamine (5-HT) release from the hippocampal and hypothalamic slices of euthermic and hibernating Richardsons' ground squirrels was therefore investigated. DADLE (0.1-10 microM) had no effect on 5-HT release in the hypothalamic slices but elicited a dose-related inhibition on [3H]-5-HT release from the hippocampal slices of the euthermic ground squirrel. The inhibitory effect of DADLE was completely reversed by naloxone (10 microM), but not by tetrodotoxin (1 microM). In contrast, DADLE failed to alter the K(+)-induced 5-HT release from the hippocampal slices of the hibernating ground squirrel. This state-dependent reduction in responsiveness to an opioid is consistent with the hypothesis that enhanced endogenous opioid activity in the hibernating phase could lead to down regulation of the opioid receptors and minimize its inhibition on hippocampal serotonergic activity. A high 5-HT activity would inhibit midbrain reticular activating system indirectly through non-serotonergic fibers, which in turn facilitate the onset or maintenance of hibernation.

Animals↗
PubMed1990

New Taxanes from Taxus chinensis.

Two new taxane diterpenes, decinnamoyltaxagifine ( 3) and decinnanioyltaxagifine acetate ( 2), have been isolated from the leaves and stems of TAXUS CHINENSIS. Their structures were elucidated by spectroscopic methods. Their (13)C-NMR chemical shifts were assigned.

Journal Article↗
PubMed1990

[Effects of promethazine on acupuncture analgesia].

Promethazine, one of histaminergic H1-receptor antagonist, was often used as an adjuvant drug prior to and during acupuncture anesthesia in clinics, However, its effects was not known clearly. By using potassium iontophoretic dolorimetry and stimulating unilateral "Hegu" and "Waiguan" points with electroacupuncture (EA) in 42 rabbits, we found that Promethazine could drop the pain threshold in small dosages (0.5 mg/kg, 1 mg/kg) and raise the pain threshold in relatively large dosages (2 mg/kg, 4 mg/kg). In different dosages (1 mg/kg, 2 mg/kg), promethazine could attenuate the analgesic effect of EA. It was suggested that promethazine should be used carefully in acupuncture anaesthesia.

Acupuncture Analgesia↗
PubMed1989

[Negative inotropic effect of 3,6-dimethamidodibenzopyriodonium citrate (I-65) on guinea pig papillary muscles].

The effects of 3,6-dimethamidodibenzopyriodonium citrate (I-65) on the contractile response of electrically paced guinea pig papillary muscles in vitro were studied. I-65 (0.1-300 mumol/L) decreased the contractile force and inhibited isoprenaline-induced restoration of the contractile response in papillary muscles rendered inexcitable by KCl 22 mmol/L. Both effects were concentration-dependent, and the IC50 were 36.0 and 7.3 mumol/L, respectively. I-65 antagonized the positive inotropic effects of Iso and CaCl2 in a non-competitive manner. Like verapamil, I-65 had a frequency-dependent negative inotropic effect, and delayed the recovery of post-rest potentiation. It is concluded that the negative inotropic effect of I-65 results not only from the reduction of Ca2+-influx through the sarcolemmal membrane, but also from the inhibition of Ca2+ translocation in the sarcoplasmic reticulum.

Animals↗
PubMed1989

[Effects of 3,6-dimethamidodibenzopyriodonium citrate (I-65) on action potentials and contractions in guinea pig papillary muscles].

Synchronous recordings of action potentials and contractile force in isolated guinea pig papillary muscles administered 3,6-dimethamidodibenzopyriodonium citrate (I-65) 30 mumol/L showed excitation-contraction uncoupling, ie, the contractile force was markedly depressed although the Vmax and amplitudes of the action potentials were unaffected. At the same concentration, I-65 shortened the duration of the action potentials at 50% and 90% repolarization. However, I-65 at lower concentrations (1-10 mumol/L) decreased Vmax and the amplitude of the slow action potentials which were elicited by isoprenaline in papillary muscles were rendered partially depolarized by KCl 25 mmol/L Tyrode solution. These effects were partially reversed by elevation of the concentration of Ca2+ from 2.7 to 5.4 mmol/L. I-65 also suppressed the abnormal automaticity elicited by BaCl2 and DAD and triggered activity induced by ouabain. The results suggest that I-65 may be a calcium channel blocker.

Action Potentials↗