Biomedical subjects

Y Fang

Publications and source records attributed to Y Fang.

At least 163 records · Page 9Linked to original sources

PubMed1998

[An investigation on chromosome aberration of SO-Rb50 cloned cell strains].

PURPOSE: To compare the differences of chromosome aberration among 3 cloning cells (MC2, MC3 and MC4) of SO-Rb50 cell line. METHOD: G-banding and karyotype analysis were performed on the 11th passage cells of MC2, MC3 and MC4 cell strains. RESULTS: Both numerical abnormal and structural aberrations of chromosomes could be observed in these 3 cloned cell strains. Diploid cells had the preponderance over the aneuploid cells. However, some cells showed pseudiploid karyotypes. Several kinds of structural chromosome aberrations were observed. The chromosome aberrations in the same passage of different cell strains were different. Aberration of chromosome 13 was rare and the aberration feature were different in 3 cloned cell strains. Five marker chromosomes were identified. M1, t(1;1) qterp35::q24-ter could be found in all cell strains. Other markers were seen in different cell strains respectively. In our experiment, two marker chromosome in chromosome 2, M4 and M5, were found in SO-Rb50 cell line for the first time. CONCLUSION: Chromosome aberrations were different with different cloned cell strains. Combined with formerly study in SO-Rb50 cell line, we found the chromosome aberration had dynamic changes during the long-term culture in vitro. We suggest that aberration of chromosome 13 is not the only cause of Rb; aberration of chromosome 1, a common event in some neoplasias as well as in SO-Rb50, plays a meaningful role in the immortalization of this cell line; other aberrations observed in our experiment could be considered as evidences of genomic instability of the cell strains and presumably enhance the growth potential of the cells in which they develop.

Cell Line↗

PubMed1998

[Study on the NIR-Raman spectra and NIR-SERS spectra of amsacrine].

The near infrared surface-enhanced Raman spectra (NIR-SERS) of amsacrine,an anticancer agent, on silver collids were recored with high quality. The NIR-SERS enhancement factor is up to 10(4) magnitude. In comparison with the near infrared Raman (NIR-Raman) spectra of solid amsacrine, more information of vibrational structures of amsacrine molecules at low concentration and almost in its practical application envi ronment, can be given by the NIR-SERS. The enhancement mechanism is associated with the adsorption of acridyl ring and sulfonyl on silver surface.

Amsacrine↗

PubMed1998

Comparison of the antimuscarinic and antispasmodic actions of racemic oxybutynin and desethyloxybutynin and their enantiomers with those of racemic terodiline.

Racemic oxybutynin (CAS 1508-65-2) is used clinically to treat urinary incontinence and reportedly undergoes N-deethylation to metabolites R- and/or S-desethyloxybutynin. To assess the role of these metabolites in the therapeutic effects of oxybutynin, the antimuscarinic and antispasmodic effects of RS-, R- and S-oxybutynin, RS-, R- and S-desethyloxybutynin and, for comparative purposes, RS-terodiline (CAS 7082-21-5) on isolated strips of guinea pig bladder, were examined. All of these compounds exhibited antimuscarinic activity: they competitively antagonized carbachol-induced contractions, with mean pA2 values (+/- S.E.) of 8.91 +/- 0.20, 8.80 +/- 0.27, 7.09 +/- 0.13, 8.55 +/- 0.32, 9.04 +/- 0.32, 7.31 +/- 0.35 and 6.77 +/- 0.22, respectively. Consistent with an antispasmodic action, all of the compounds produced similar inhibition of potassium-induced contraction; the mean IC50 values for reducing responses to 137.7 mmol/l potassium were between 2.22 and 5.68 mumol/l. Thus, RS- and R-oxybutynin and RS- and R-desethyloxybutynin exhibited high antimuscarinic activity relative to their antispasmodic activity, while S-oxybutynin, S-desethyloxybutynin and RS-terodiline exhibited relatively weak antimuscarinic activity. It is concluded that deethylation of oxybutynin to desethyloxybutynin does not appreciably alter its antimuscarinic or antispasmodic activity and that R- and/or S-desethyloxybutynin probably contribute significantly to the pharmacological properties of oxybutynin in humans. In addition, since the relative potency of the antimuscarinic-to-antispasmodic actions of S-oxybutynin was equivalent to that of RS-terodiline, S-oxybutynin deserves consideration for development as a single-enantiomer drug for the treatment of urinary incontinence. It may produce the same beneficial therapeutic effects as both RS-terodiline and RS-oxybutynin but, like RS-terodiline, produce a lower incidence of antimuscarinic side-effects than seen with RS-oxybutynin.

Animals↗

PubMed1997

Cocaine exposure in fetal rhesus monkey: consequences for dopamine D1- and D2-like receptor binding densities.

Previously we found that dopamine D1-, D2- and D5-receptor mRNA subtypes are significantly increased in the rostral forebrain of fetal monkeys exposed to cocaine. The purpose of the present study was to determine whether cocaine exposure during gestation also increases dopamine receptor binding densities in the fetal brain. Pregnant monkeys were treated with cocaine (3 mg/kg, i.m., n = 3) or physiological saline (n = 3), 4 times per day from day 22 of pregnancy until day 70. Quantitative receptor autoradiography of dopamine D1-like receptors was performed on day-70 fetal brain sections using [3H]SCH23390. [3H]Spiperone was used to characterize dopamine D2-like receptors. Image analysis of receptor autoradiograms revealed a high-density dopamine D1-like receptor binding in the striatum, nucleus accumbens (ACB) and the substantia nigra (SN), whereas lower binding densities were observed in the frontal cortex and the habenula (Hb). Dopamine D2-like receptor binding was also found in the frontal cortex, striatum and ACB, but was not detected in the Hb or SN. The pattern of dopamine receptor distribution was the same in both control and cocaine-treated animals. However, there was a significant increase in the density of sites for D1-like receptors in the striatum (P < 0.05) and SN (P < 0.01) and for D2-like receptors in the striatum (P < 0.01) of cocaine-treated animals versus saline-treated controls. These findings suggest that D1- and D2-like receptors are present in dopamine target neurons, whereas D2-like autoreceptors can not be detected in day-70 fetal monkey midbrain. The present results provide further support for the hypothesis that gestational cocaine exposure causes reduced synthesis and release of dopamine which leads to dopamine D1- and D2-receptor up-regulation in dopamine target neurons.

Animals↗

PubMed1997

Conformation of beta-Lactoglobulin Studied by FTIR: Effect of pH, Temperature, and Adsorption to the Oil-Water Interface.

The structure of mixed A and B genetic variants of beta-lactoglobulin (beta-lg) in its native and denatured states has been studied by FTIR. The denaturation was achieved through either heating at various temperatures at pH 6 and 7 or by adsorption to the surfaces of oil droplets in oil-in-water emulsions. The time dependence of the structural changes of the adsorbed protein was also studied. It was found that beta-lg was more resistant to heat denaturation at pH 6 than at pH 7. Conversely, the adsorbed protein appeared to be more deformable at pH 6 than at pH 7. Although heating at lower temperatures (70 and 80 degreesC) for a longer time causes extensive denaturation, as does heating at higher temperature (90 degreesC) for a short time, the structure of the denatured protein was different in the two cases. When denatured at lower temperatures, more beta-structure remained as indicated by the presence of bands around 1632 cm-1 in the IR spectrum, whereas evidence for extensive intermolecular beta-structure was found on the sample heated at higher temperature, indicated by the strong adsorption band at 1684 cm-1. This explains that although gelation of the protein can be achieved in both cases, the gel structure may be different. Denaturation of beta-lg during heat treatment and upon adsorption appears to occur via similar intermediate structures, which begin with the loss of beta-sheet structure, but whereas heat denaturation generates more intermolecular beta-sheet and a small amount of unordered structure, adsorption of the protein to the oil-water interface induces a larger amount of unordered structure and a small amount of intermolecular beta-sheet. The denaturation of beta-lg on the interface is a much slower process compared to heat denaturation; even though some changes are detectable shortly after the adsorption of the protein, more extensive denaturation occurs during storage of the emulsions for 72 h. Copyright 1997 Academic Press.

Journal Article↗

PubMed1997

Mice lacking dopamine D4 receptors are supersensitive to ethanol, cocaine, and methamphetamine.

The human dopamine D4 receptor (D4R) has received considerable attention because of its high affinity for the atypical antipsychotic clozapine and the unusually polymorphic nature of its gene. To clarify the in vivo role of the D4R, we produced and analyzed mutant mice (D4R-/-) lacking this protein. Although less active in open field tests, D4R-/- mice outperformed wild-type mice on the rotarod and displayed locomotor supersensitivity to ethanol, cocaine, and methamphetamine. Biochemical analyses revealed that dopamine synthesis and its conversion to DOPAC were elevated in the dorsal striatum from D4R-/- mice. Based on these findings, we propose that the D4R modulates normal, coordinated and drug-stimulated motor behaviors as well as the activity of nigrostriatal dopamine neurons.

3,4-Dihydroxyphenylacetic Acid↗

PubMed1997

The heptameric prepore of a staphylococcal alpha-hemolysin mutant in lipid bilayers imaged by atomic force microscopy.

We have used atomic force microscopy to study the oligomeric state of a genetically engineered mutant of staphylococcal alpha-hemolysin (alphaHL-H5) that can be arrested as a "prepore" assembly intermediate. AFM images of alphaHL-H5 on supported bilayers of a fluid-phase lipid, egg-yolk phosphatidylcholine (egg-PC), under conditions that lock alphaHL-H5 into the prepore state, clearly show a heptameric structure for many individual oligomers. The central dent of the prepore has a diameter of 3.2 +/- 0.2 nm. The distance between the centers of mass of neighboring subunits is 2.8 +/- 0.3 nm. The heptamer has an average diameter of 8.9 +/- 0.6 nm. These results support a recently proposed pathway for the assembly of alpha-hemolysin.

Bacterial Toxins↗

PubMed1997

Expression of early nodulin genes in alfalfa mycorrhizae indicates that signal transduction pathways used in forming arbuscular mycorrhizae and Rhizobium-induced nodules may be conserved.

Transcripts for two genes expressed early in alfalfa nodule development (MsENOD40 and MsENOD2) are found in mycorrhizal roots, but not in noncolonized roots or in roots infected with the fungal pathogen Rhizoctonia solani. These same two early nodulin genes are expressed in uninoculated roots upon application of the cytokinin 6-benzylaminopurine. Correlated with the expression of the two early nodulin genes, we found that mycorrhizal roots contain higher levels of trans-zeatin riboside than nonmycorrhizal roots. These data suggest that there may be conservation of signal transduction pathways between the two symbioses-nitrogen-fixing nodules and phosphate-acquiring mycorrhizae.

Journal Article↗

PubMed1997

The growth of bilayer defects and the induction of interdigitated domains in the lipid-loss process of supported phospholipid bilayers.

The lipid-loss process has been studied with in situ atomic force microscopy (AFM) at six different temperatures for supported dipalmitoylphosphatidylcholine (DPPC) bilayers. A typical structural characteristic is the creation and the growth of bilayer defects as lipid molecules are lost from the bilayer. The rate of the lipid loss has an Arrhenius behavior, with an activation energy of 37 kT, where kT is the thermal energy at room temperature. For the lipid-loss processes at temperatures above 45 degrees C, interdigitated membrane domains are induced and are mostly in contact with some bilayer defects. These domains disappear at the increase of the area of bilayer defects. Possible mechanisms of these phenomena are discussed.

1,2-Dipalmitoylphosphatidylcholine↗

PubMed1997

Involvement of endogenous orphanin FQ in electroacupuncture-induced analgesia.

Recent studies suggest that the novel opioid peptide orphanin FQ (OFQ) is involved in pain modulation. We found that intracerebroventricular (i.c.v.) administration of OFQ in the rat produced a dose-dependent antagonism of the analgesia induced by 100 Hz electroacupuncture (EA) stimulation as measured in the radiant heat tail-flick assay. Antisense oligonucleotides injected i.c.v. potentiated EA analgesia, presumably by interfering with the expression of the OFQ receptor in brain. These results suggest that endogenous OFQ exerts a tonic antagonistic effect on EA-induced analgesia. No such antagonism was observed when OFQ was injected intrathecally (i.t.). Rather, it appears that spinal OFQ produced a marked analgesic effect and enhanced EA-induced analgesia. These findings are consistent with the experimental results obtained in rats where morphine-induced analgesia is antagonized by i.c.v. OFQ and potentiated by i.t. OFQ.

Analgesia↗

PubMed1997

Bidirectional modulatory effect of orphanin FQ on morphine-induced analgesia: antagonism in brain and potentiation in spinal cord of the rat.

1. The present study was designed to investigate further the effects of the newly discovered orphanin FQ (OFQ)-the endogenous ligand for the orphan opioid receptor (called, e.g., ORL, and LC132)-on pain modulation in the rat. We used the tail-flick assay as a nociceptive index. 2. When injected into a cerebral ventricle, OFQ (4 fmol-10 nmol) has no effect on basal tail-flick latency by itself at any dose, but dose-dependently antagonizes systemic morphine analgesia (400 fmol 50 nmol). 3. Injected intrathecally, OFQ (3 and 10 nmol) displayed an analgesic effect without producing motor dysfunction, and potentiated morphine analgesia (1 and 10 nmol). 4. The anti-opioid effect of OFQ in rat brain and the high level of expression of LC132/ORL, receptor in the locus coeruleus indicated a possible role of OFQ in the precipitation of opiate withdrawal symptoms. However, no such precipitation was observed by OFQ in morphine-dependent rats.

Analgesia↗

PubMed1997

Hydrated water molecules of pyrimidine/purine/pyrimidine DNA triple helices as revealed by FT-IR spectroscopy: a role of cytosine methylation.

Hydrated water molecules of pyrimidine/purine/pyrimidine DNA hairpin triplex was studied by a comparison of triplex (CC.AG6) formed by a host oligodeoxypyrimidine of 5'-d(TC)3T4(CT)3(CC) with a target hexadeoxypurine 5'-d(AG)3(AG6) strand and by triplexes (MM.AG6, MC.AG6, and CM.AG6) formed by oligonucleotides with the exact sequences as above except 5-methylcytosine replaced all (MM), 5' end half (MC), and 3' end half (CM) cytosine bases in CC via FT-IR spectroscopy in hydrated film. Results revealed that: (i) all these triplexes have a similar hydration pattern, in which water molecules probably bound in the N7 sites of adenines and guanines in the Crick-Hoogsteen groove, and to the methyl group of thymidines in the Watson-Hoogsteen groove. There are also some bound water molecules found at the O2 sites of thymines in both Watson-Crick and Crick-Hoogsteen grooves. (ii) In the CC.AG6 triplex the S-type sugars are always dominant in all hydrated states, whereas in MM.AG6 triplex the relative population of the N-type sugars is very close to that of the S-type between 86% and 66% of humidity. Furthermore, the sugar conformation in two partially modified triplexes (CM.AG6, and MC.AG6) are dominant by the N-type at lower humidity. This phenomenon might reflect that the degree of bound water varies among the binding sites of bases. (iii) The effect of introducing a methyl group on cytosine is to generate a spine of hydrophobic region in MM (MC and MC). The enlarging hydrophobic area not only increase the stability in solution, and also the stability in sodium hydrated films of the pyrimidine/purine/pyrimidine hairpin triplexes.

Cytosine↗

PubMed1997

Formation and characteristics of an unusual lambda-DNA species.

An unusual DNA species, termed as DNA species A, has been isolated and purified from thermal-denatured lambda-DNA Hind III by Sephadex G-200 gel filtration. Our studies indicate that DNA species A is resistant to DNase I digestion and has a higher melting point. The new DNA species showed a lower absorbency at 260 nm, and a lower fluorescence quantum yield after interaction with ethidium bromide (EB) than native double-stranded lambda-DNA. CD spectrum of DNA species A consists of a broad positive band centered at 245 nm and a weak negative band at 220 nm. transmission electron microscope (TEM) visualizations showed that their lengths of DNA species A fell mainly in three regions (300-500 nm, 750-1000 nm and 1500 nm) that corresponded to three fluorescence bands in the EB-stained gels. Their apparent width and height were 65-75 nm and 2.2 nm respectively as observed by images of atomic force microscope (AFM).

Circular Dichroism↗

PubMed1997

Acceleration of sodium-calcium exchange activity during ATP-induced calcium release in transfected Chinese hamster ovary cells.

The P2U purinergic agonist ATP (0.3 mM) elicited an increase in [Ca2+]i due to Ca2+ release from intracellular stores in transfected Chinese hamster ovary cells that express the bovine cardiac Na+/Ca2+ exchanger (CK1.4 cells). The following observations indicate that ATP-evoked Ca2+ release was accompanied by a Ca(2+)-dependent regulatory activation of Na+/Ca2+ exchange activity: Addition of extracellular Ca2+ (0.7 mM) 0-1 min after ATP evoked a dramatic rise in [Ca2+]i in Na(+)-free media (Li+ substitution) compared to Na(+)-containing media; no differences between Na(+)- and Li(+)-based media were observed with vector-transfected cells. In the presence of physiological concentrations of extracellular Na+ and Ca2+, the ATP-evoked rise in [Ca2+]i declined more rapidly in CK1.4 cells compared to control cells, but then attained a long-lived plateau of elevated [Ca2+]i which eventually came to exceed the declining [Ca2+]i values in control cells. ATP elicited a transient acceleration of exchange-mediated Ba2+ influx, consistent with regulatory activation of the Na+/Ca2+ exchanger. The acceleration of Ba2+ influx was not observed in vector-transfected control cells, or in CK1.4 cells in the absence of intracellular Na+ or when the Ca2+ content of the intracellular stores had been reduced by prior treatment with ionomycin. The protein kinase C activator phorbol 12-myristate 13-acetate attenuated the exchange-mediated rise in [Ca2+]i under Na(+)-free conditions, but did not inhibit the ATP-evoked stimulation of Ba2+ influx. The effects of PMA are therefore not due to inhibition of exchange activity, but probably reflect the influence of protein kinase C on other Ca2+ homeostatic mechanisms. We conclude that exchange activity is accelerated during ATP-evoked Ca2+ release from intracellular stores through regulatory activation by increased [Ca2+]i. In the absence of extracellular Ca2+, the stimulation of exchange activity is short-lived and follows the time course of the [Ca2+]i transient; in the presence of extracellular Ca2+, we suggest that the exchanger remains activated for a longer period of time, thereby stabilizing and prolonging the plateau phase of store-dependent Ca2+ entry.

Adenosine Triphosphate↗

PubMed1997

Differential in vivo regulation of steroid hormone receptor activation by Cdc37p.

The CDC37 gene is essential for the activity of p60(v-src) when expressed in yeast cells. Since the activation pathway for p60(v-src) and steroid hormone receptors is similar, the present study analyzed the hormone-dependent transactivation by androgen receptors and glucocorticoid receptors in yeast cells expressing a mutant version of the CDC37 gene. In this mutant, hormone-dependent transactivation by androgen receptors was defective at both permissive and restrictive temperatures, although transactivation by glucocorticoid receptors was mildly defective only at the restrictive temperature. Cdc37p appears to function via the androgen receptor ligand-binding domain, although it does not influence receptor hormone-binding affinity. Models for Cdc37p regulation of steroid hormone receptors are discussed.

Amino Acid Sequence↗

PubMed1997

Interactions of Na+, H2O2 and the Na+-Ca2+ exchanger stimulate Ca2+ release in CK1.4 cells.

1. The present study aimed to demonstrate that interaction of cations, hydrogen peroxide (H2O2) and the Na(+)-Ca2+ exchanger stimulate Ca2+ release and oscillations of cytosolic Ca2+[Ca2+]i in non-transfected Chinese Hamster Ovary (CHO) C1 cells and in transfected CHO (CK1.4) cells that contained an expression vector coding the Na(+)-Ca2+ exchanger sequence. 2. The [45Ca2+] uptake assay, fura-2 fluorescence imaging and 2(2) and 2(3) factorial orthogonal statistics provide comparative, direct, efficient, quantitative and transient methods to delineate the effects of such interactions on Ca2+ influx, Ca2+ release and [Ca2+]i in C1 and CK1.4 cells. 3. In contrast to the control of either Na(+)-, Ca2(+)- or H2O2-free or C1 cells, an elevated [45Ca2+] uptake was induced by Ca2+, Na+ and H2O2 individually and in combination, intra-cellular Ca2+ release was activated by H2O2, and by combinations of either H2O2 and Na+, H2O2 and the Na(+)-Ca2+ exchanger, Na+ and the Na(+)-Ca2+ exchanger or by H2O2, Na+ and the Na(+)-Ca2+ exchanger and a rise in [Ca2+]i was triggered by H2O2, Na+ and a combination of Na+ and the Na(+)-Ca2+ exchanger. 4. These results indicate that interactions between H2O2, Na+ and the Na(+)-Ca2+ exchanger stimulate intracellular Ca2+ mobilization via Ca2(+)-induced Ca2+ release mechanisms, ATP-activated G-protein coupled P2y-purinoceptor-sensitive pathways, Na(+)-Ca2+ exchanger-mediated Ca2+ influx and cation-pi interaction (a strong non-covalent force between the cation and the pi face of an aromatic structure in the transmembrane protein). 5. The present findings provide important clues for understanding Ca2+ signal transduction mechanisms from the plasma membrane to the endoplasmic reticulum.

Animals↗

PubMed1997

[Regulation of cardiovascular myogenic tone via G-protein-sensitive transmembrane signal pathways].

Effects of cellular hypoxia on [Ca2+]i in CK1.4 cells expressed Na(+)-Ca2+ exchange protein were determined by fura-2 fluorescence imaging. In vitro perfused of canine cardiovascular samples (37 degrees C), changes of aortic, cervical, pulmonary arterial smooth myogenic tone and cardiac papillary myogenic tone were measured by mechanic-electrical transducers via a computer-aid autosampling system. In the whole dogs, pharmacolkinetic parameters of a VISA agent at three dosages were calculated by 125Isod-1 scintillation counting according to a 6 x 6 statistical model. The results indicated that 1. hypoxia inhibited the Na(+)-Ca2+ exchange protein induced by and elevated Ca(2+)-influx and [Ca2+]i in the CK1.4 cells; 2. hypoxic perfusions depressed the AlF4-(-)activated myogenic vasoconstriction in aortic, cervical and pulmonary arteries, but facilitated the cardiac papillary myogenic contraction Ca(2+)-influx-induced, the finding was consistent with the first result; and 3. the VISA agent distributed in the cell together with AlF4- simulated and activated G-protein-sensitive transmembrane sygnal, and signhificantly improved the oxidative injuries of the transmembrane macrowolecules and cardiovascular contraction proteins such as Na(+)-Ca2+ exchange protein induced by hypoxia.

Animals↗

PubMed1997

[Effect of dietary arginine on peripheral blood Th/Ts ratio and survival rate in severe burned rats].

The effect of supplemental dietary arginine on dynamic changes in peripheral blood Th/ Ts ratio and survival rate were studied in burned rats (30% TBSA III degree). The results are as follows: 1. Th/Ts ratio dropped on the 3rd day and showed a trough value 10 days postburn. 2. Arginine could prevent the falling of Th/Ts ratio, which was distinct since 5 days after burn. 3. Survival rate 14 days postburn was raised in arginine rats. This study suggests that dietary arginine may be beneficial after severe burn.

Adjuvants, Immunologic↗