Biomedical subjects

Y Fang

Publications and source records attributed to Y Fang.

At least 127 records · Page 7Linked to original sources

PubMed1999

[Adhesive otitis media with cholesteatoma].

OBJECTIVE: To explore the mechanism of cholesteatoma formation in adhesive otitis media with cholesteartoma. METHOD: Three cases of this kind of disease were reported and literatures were also reviewed. RESULT AND CONCLUSION: 1. It is a acquired primary cholesteatoma. 2. The eustachian tube and tympanic isthmus block are the direct cause of these cholesteatoma. 3. CT examination of the temporal bone is more valuable in diagnosis than that of normal X-ray. 4. If the cholesteatoma lesions can be removed completly, tympanoplasty may be performed in first stage or separate stage.

Adult↗

PubMed1999

[Research into simultaneous determination of five components by ridge regression spectrophotometry].

Ridge regression spectrophotometry (LHG) is one of the computational spectrophotometry developed recently. It is used in this paper to the analysis of five component s--acetaminophen, p -aminophenol. p -nitrophenol. p -acetaminophenol acetic acid ester and p -nitrophenol acetic acid ester. The choose of medium and the determination of the amount of mixed standard solution were described in detail. The experimental results show that in the medium of 0.1 mol x L(-1) HCI, the recovery ratio of each component ranges from 95.5% to 106.1% and the RSD ranges from 0.8% to 9.8%. This approach is simple and suitable for the computer-aid analysis. The approach has been used to the analysis of the sample in the course of synthetic acetaminophen.

English Abstract↗

PubMed1999

[Research into determination of tricomponent sample by ridge regression spectrophotometry].

In this paper ridge regression spectrophotometry was used to analyze three components--Acetaminophen, P-Ni-trophenol and P-Aminophenol with absolute ethanol as the solvent. The basic principle and analytical steps of the method were described in detail. The experimental results show that the recovery of each component ranges from 99.24% to 101.31% with the medium of absolute ethanol. As compared with conventional methods, this method is simple, rapid and suitable for computer-aid analysis.

Acetaminophen↗

PubMed1998

Generation of destabilized green fluorescent protein as a transcription reporter.

The green fluorescent protein (GFP) is a widely used reporter in gene expression and protein localization studies. GFP is a stable protein; this property allows its accumulation and easy detection in cells. However, this stability also limits its application in studies that require rapid reporter turnover. We created a destabilized GFP for use in such studies by fusing amino acids 422-461 of the degradation domain of mouse ornithine decarboxylase (MODC) to the C-terminal end of an enhanced variant of GFP (EGFP). The fusion protein, unlike EGFP, was unstable in the presence of cycloheximide and had a fluorescence half-life of 2 h. Western blot analysis indicated that the fluorescence decay of EGFP-MODC-(422-461) was correlated with degradation of the fusion protein. We mutated key amino acids in the PEST sequence of EGFP-MODC-(422-461) and identified several mutants with variable half-lives. The suitability of destabilized EGFP as a transcription reporter was tested by linking it to NFkappaB binding sequences and monitoring tumor necrosis factor alpha-mediated NFkappaB activation. We obtained time course induction and dose response kinetics similar to secreted alkaline phosphatase obtained in transfected cells. This result did not occur when unmodified EGFP was used as the reporter. Because of its autofluorescence, destabilized EGFP can be used to directly correlate gene induction with biochemical change, such as NFkappaB translocation to the nucleus.

Amino Acid Sequence↗

PubMed1998

[Effects of smoking on interleukin-2 and its receptor system in human peripheral blood].

42 healthy male smokers and 42 healthy male nonsmokers matched in age and life style were strictly chosen into the study from Beijing urban and rural areas. Peripheral blood mononuclear cells(PBMCs) were separated and then stimulated by PHA under 37 degrees C, 5% CO2 condition. Immunochemical methods were applied in testing the synthesis of interleukin 2(IL-2) and the expression of its membrane receptor (mIL-2R) and the level of soluble receptor (sIL-2R) in serum. The results showed that when compared with nonsmokers, stimulated PBMC from smokers had significant higher percentage of mIL-2R positive cells (P < 0.05) in vitro. Levels of sIL-2R in serum of smokers were also significantly higher than those of nonsmokers (P < 0.05). The percentage of IL-2 secrete cells of smokers had higher tendency (P = 0.08). These data indicated that the immune function of smokers and nonsmokers are different concerning the IL-2 and its receptor system.

Adult↗

PubMed1998

Cloning, chromosomal localization and promoter analysis of the human transcription factor YY1.

Yin Yang 1 (YY1) is a protein that activates and represses transcription of a large number of cellular and viral genes. In addition, studies suggest that YY1 may play an important role in development and differentiation. Here, we report the isolation and analysis of a YY1 genomic clone from a lambda human liver library. Fluorescence in situ hybridization with the YY1 clone has localized the YY1 gene to chromosome 14 band q32. A major YY1 gene transcription initiation site has been mapped to 478 bp upstream of the ATG translation start site. The proximal promoter contains multiple Sp1 transcription factor binding sites but lacks a consensus TATA or CCAAT box. Transient transfections and detailed deletion analyses localized the promoter to no more than 277 bp upstream from the major transcription start site. Finally, we have found that overexpression of the adenovirus E1A protein represses expression of a reporter gene directed by the YY1 promoter.

Adenovirus E1A Proteins↗

PubMed1998

Real-time isoform analysis by two-dimensional chromatography of a monoclonal antibody during bioreactor fermentations.

A humanized monoclonal antibody specific for L-selectin exhibits two distinct isoforms that are distinguishable by a charged group modification on one of the antibody light chains. The added charge allows baseline separation of the isoforms by anion-exchange chromatography. Since this modification most likely results from specific enzymatic activity within the Golgi complex, it is possible that fermentation conditions may affect the relative amounts of the isoforms produced. Herein is described a two-dimensional chromatographic method for quantifying the relative amounts of the isoforms from fermentation broths, in real time.

Antibodies, Monoclonal↗

PubMed1998

Changes in the midbrain-rostral forebrain dopamine circuitry in the cocaine-exposed primate fetal brain.

To ascertain cocaine's effects in the fetus, we developed a nonhuman primate model in which pregnant monkeys were administered cocaine (3 mg/kg i.m.) or saline four times a day from day 20 through days 40-70 of a 165-day gestation. At the time of cesarean section, plasma levels of cocaine in fetal blood were 231 +/- 70 ng/ml. Fetal brains were examined using immunocytochemistry, in situ hybridization, receptor autoradiography, and nuclease protection assay analysis. No differences were found in the expression of tyrosine hydroxylase and dopamine receptor mRNAs by days 40-45 of gestation. However, by day 60 the midbrain of monkeys exposed to cocaine had significantly reduced expression of tyrosine hydroxylase, the rate-limiting enzyme in dopamine synthesis. Moreover, dopamine D1 and D2 receptor mRNAs were significantly elevated in the rostral forebrain as were D1 and D2 receptor binding sites in days 60-70 cocaine-exposed fetuses. Cocaine treatment from day 20 to days 60 and 70 of gestation also significantly increased the mRNA concentrations of dynorphin and enkephalin in the rostral forebrain. These findings suggest that in utero cocaine exposure has profound effects on the developing dopamine neurocircuitry.

Amniotic Fluid↗

PubMed1998

The role of GM1 and other gangliosides in neuronal differentiation. Overview and new finding.

The pronounced increases in gangliosides belonging to the gangliotetraose family during the neurite outgrowth phase of neuronal differentiation have suggested a functional requirement for these substances related to process extension, arborization, and possibly synaptogenesis. Support for this hypothesis has come from a variety of experimental paradigms utilizing neuroblastoma cell lines, primary neuronal cultures, and observations on the developing nervous system. We have recently observed that differentiation of both primary neurons and neuroblastoma cells by Ca(2+)-elevating stimulants is characterized by upregulation of GM1 in the nuclear membrane. Immunostaining revealed these Ca(2+)-induced neurites to have axonal characteristics. Recent work has indicated that nuclear GM1 facilitates efflux of nuclear Ca2+, thereby contributing to the reduced level of nuclear Ca2+ that characterizes the differentiated neuron. Thus, while GM1 is generally recognized as a pluripotent molecule with several modulatory roles in the plasma membrane of developing and mature neurons, regulation of Ca2+ flux across the nuclear membrane is proposed as another critical function of this ganglioside in neuronal development, with special relevance to axonogenesis.

Animals↗

PubMed1998

Modulation of an early step in the secretory machinery in hippocampal nerve terminals.

In hippocampal neurons, neurotransmitter release can be regulated by protein kinase A (PKA) through a direct action on the secretory machinery. To identify the site of PKA modulation, we have taken advantage of the ability of the neurotoxin Botulinum A to cleave the synaptic protein SNAP-25. Cleavage of this protein decreases the Ca2+ responsiveness of the secretory machinery by partially uncoupling Ca2+-sensing from fusion per se. This is expressed as a shift toward higher Ca2+ levels of the Ca2+ to neurotransmitter release relationship and as a perturbation of synaptic delay under conditions where secretion induced by the Ca2+-independent secretagogue ruthenium red is unimpaired. We find that SNAP-25 cleavage also perturbs PKA-dependent modulation of secretion; facilitation of ruthenium red-evoked neurotransmitter release by the adenylyl cyclase activator forskolin is blocked completely after Botulinum toxin A action. Together with our observation that forskolin modifies the Ca2+ to neurotransmitter release relationship, our results suggest that SNAP-25 acts as a functional linker between Ca2+ detection and fusion and that PKA modulates an early step in the secretory machinery related to calcium sensing to facilitate synaptic transmission.

Animals↗

PubMed1998

Expression of complement receptors 1 and 2 on follicular dendritic cells is necessary for the generation of a strong antigen-specific IgG response.

Two mechanisms could account for the impaired humoral immune response found in Cr2-/- mice. The absence of complement receptors 1 and 2 (CR1, CR2) on B cells could affect their activation. Alternatively, impaired Ag trapping by follicular dendritic cells (FDC) could affect B cell maturation into Ig-secreting or memory B cells. To compare the roles of CR1 and CR2 on B cells vs FDC in this abnormal response, bone marrow (BM) chimeric mice were generated and immunized with specific T-dependent Ags. The primary and secondary Ab response was measured. Cr2+/+ animals reconstituted with a Cr2-/- BM generated a diminished but detectable humoral immune response compared with controls. When injected with preformed immune complexes (IC), these mice maintained follicular IC localization. Cr2-/- animals reconstituted with a Cr2+/+ BM had an initial rise in the Ab titer, but were unable to maintain it as shown by a pronounced decrease in the IgG titer. This defect persisted during the secondary immune response. Follicular IC trapping was also impaired. Despite the abnormal Ab response, germinal center formation was retained in all of the chimeric animals. These experiments are the first to demonstrate an absolute requirement for CR1 and CR2 expression on FDC in the generation of a normal humoral immune response.

Animals↗

PubMed1998

Solid-state DNA sizing by atomic force microscopy.

Atomic force microscopy (AFM) allows rapid, accurate, and reproducible visualization of DNA adsorbed onto solid supports. The images reflect the lengths of the DNA molecules in the sample. Here we propose a solid-state DNA sizing (SSDS) method based on AFM as an analytical method for high-throughput applications such as finger-printing, restriction mapping, +/- screening, and genotyping. For this process, the sample is first deposited onto a solid support by adsorption from solution. It is then dried and imaged under ambient conditions by AFM. The resulting images are subjected to automated determination of the lengths of the DNA molecules on the surface. The result is a histogram of sizes that is similar to densitometric scans of DNA samples separated on gels. A direct comparison of SSDS with agarose gel electrophoresis for +/- screening shows that it produces equivalent results. Advantages of SSDS include reduced sample size (i.e., lower reagent costs), rapid analysis of single samples, and potential for full automation using available technology. The high sensitivity of the method also allows the number of polymerase chain reaction cycles to be reduced to 15 or less. Because the high signal-to-noise ratio of the AFM allows for direct visualization of DNA-binding proteins, different DNA conformations, restriction enzymes, and other DNA modifications, there is potential for dramatically improving the information content in this type of analysis.

Adsorption↗

PubMed1998

Synthetic diamond-based position-sensitive photoconductive detector development for the Advanced Photon Source.

A novel X-ray beam-position detection device that we call a position-sensitive photoconductive detector (PSPCD) is designed to have synthetic diamond as its substrate material. We proved that it is feasible to use synthetic diamond to make a hard X-ray position-sensitive detector based on the photoconductivity principle and that it acts as a solid-state ion chamber. Experiments on different PSPCD samples using synthetic diamond with a high-heat-flux white undulator beam, as well as with monochromatic hard X-ray beams, have been performed at the Advanced Photon Source. Recent test results with the PSPCD in the quadrant configuration as an X-ray beam-position monitor and in a multipixel array as an X-ray beam profiler are presented in this paper.

Journal Article↗

PubMed1998

Locomotor activity in D2 dopamine receptor-deficient mice is determined by gene dosage, genetic background, and developmental adaptations.

Locomotor activity is a polygenic trait that varies widely among inbred strains of mice (). To characterize the role of D2 dopamine receptors in locomotion, we generated F2 hybrid (129/Sv x C57BL/6) D2 dopamine receptor (D2R)-deficient mice by gene targeting and investigated the contribution of genetic background to open-field activity and rotarod performance. Horizontal activity of D2R-/- mice was approximately half that of drug-naive, strain-matched controls but was significantly greater than haloperidol-treated controls, which were markedly hypokinetic. Wild-type 129/SvEv and C57BL/6 mice with functional D2 receptors had greater interstrain differences in spontaneous activity than those among the F2 hybrid mutants. Incipient congenic strains of D2R-deficient mice demonstrated an orderly gene dosage reduction in locomotion superimposed on both extremes of parental background locomotor activity. In contrast, F2 hybrid D2R-/- mice had impaired motor coordination on the rotarod that was corrected in the congenic C57BL/6 background. Wild-type 129/SvEv mice had the poorest rotarod ability of all groups tested, suggesting that linked substrain 129 alleles, not the absence of D2 receptors per se, were largely responsible for the reduced function of the F2 hybrid D2R-/- and D2R+/- mice. Neurochemical and pharmacological studies revealed unexpectedly normal tissue striatal monoamine levels and no evidence for supersensitive D1, D3, or D4 dopamine receptors in the D2R-/- mice. However, after acute monoamine depletion, akinetic D2R+/- mice had a significantly greater synergistic restoration of locomotion in response to SKF38393 and quinpirole compared with any group of D2R+/+ controls. We conclude that D2R-deficient mice are not a model of Parkinson's disease. Our studies highlight the interaction of multiple genetic factors in the analysis of complex behaviors in gene knock-out mice.

Adaptation, Physiological↗

PubMed1998

mu-Opioid agonist-stimulated [35S]GTPgammaS binding in guinea pig hypothalamus: effects of estrogen.

mu-Opioid receptors play a critical role in the regulation of the female reproductive cycle, and estrogen modulates the coupling of mu-opioid receptors to a potassium channel in the basal hypothalamus (BH) of the female guinea pig. Therefore, we ascertained the distribution of mu-opioid receptors in the BH with autoradiography using the mu-opioid selective agonist [3H]DAMGO. In addition, we investigated the effects of estrogen on DAMGO- or the GABAB receptor agonist baclofen-stimulated [35S]GTPgammaS binding in the BH. Based on the high density of mu-opioid receptors, but the lack of effects of estrogen on [35S]GTPgammaS binding, we conclude that mu-opioid receptor interaction with its G-protein is not the target of estrogen's actions.

Animals↗

PubMed1998

Proopiomelanocortin (POMC) mRNA expression: distribution and region-specific down-regulation by chronic morphine in female guinea pig hypothalamus.

There is compelling evidence that endogenous opioid peptides are regulated by exogenous opiates. Our previous studies have shown that the mu-opioid receptor protein and mRNA are down-regulated in the mediobasal hypothalamus of the female guinea pig following chronic morphine treatment. In addition, electrophysiological studies have shown that hypothalamic beta-endorphin (beta-EP) neurons express mu-opioid receptors that are uncoupled and down-regulated following chronic morphine treatment. Currently, we tested the hypothesis that chronic morphine, which produces down-regulation of mu-opioid receptors, causes a down-regulation of pro-opiomelanocortin (POMC, the precursor of beta-EP) mRNA expression in female guinea pig hypothalamus. Female guinea pigs were ovariectomized and implanted subcutaneously (s.c.) with 4 x 75 mg pellets for 2 days plus six more pellets of either morphine (n = 6) or placebo (n = 6) for another 5 days. Animals were sacrificed between 1000 and 1100 h on day 7. The expression of POMC mRNA were investigated using in situ hybridization histochemistry with a guinea pig specific 35S-labeled cRNA probe in hypothalamic tissue sections. POMC mRNA was localized to the arcuate nucleus (Arc) and median eminence (ME) of the medial basal hypothalamus. The distribution pattern was the same in both morphine and placebo control animals. However, the density of silver grains was less in morphine treated animals versus placebo control animals. Overall, the level of POMC mRNA was decreased by 22% in the Arc of morphine-treated guinea pigs as compared with the placebo controls (p < 0.05). This decrease in POMC mRNA expression was even greater in the caudal Arc (28%, p < 0.01) in morphine-treated animals. These results suggested that the biosynthetic activity of POMC neurons is down-regulated with chronic exposure to morphine.

Animals↗

PubMed1998

Corticosteroids enhance the capacity of macrophages to induce Th2 cytokine synthesis in CD4+ lymphocytes by inhibiting IL-12 production.

We investigated the effects of corticosteroids on IL-12 production by mouse splenic adherent cells and the subsequent capacity of these cells to induce cytokine production by CD4+ T cells. To distinguish the effects of corticosteroids on APCs from those on T cells, only the APCs and not the T cells were exposed to corticosteroids. Treatment of splenic adherent cells with dexamethasone greatly inhibited production of IL-12, a cytokine known to enhance IFN-gamma synthesis and decrease IL-4 synthesis by CD4+ T cells. The reduction in IL-12 production by corticosteroid-treated macrophages decreased their ability to induce IFN-gamma and increased their ability to induce IL-4 synthesis in Ag-primed CD4+ T cells. Splenic adherent cells from mice treated in vivo with dexamethasone also displayed a reduced capacity to produce IL-12. These results help to resolve previous conflicting observations regarding the effects of corticosteroids on cytokine production by T cells, and indicate that while corticosteroids may directly inhibit Th1 and Th2 cytokine production in T cells, corticosteroids, by reducing IL-12 production in APCs, have the potential to indirectly enhance Th2 cytokine synthesis. Therefore, treatment of diseases such as allergy with chronic corticosteroids may indirectly exacerbate the course of the disease, which is caused primarily by the overproduction of Th2 cytokines in allergen-specific CD4+ T cells.

Adjuvants, Immunologic↗

PubMed1998

Surface-directed DNA condensation in the absence of soluble multivalent cations.

Multivalent cations are known to condense DNA into higher ordered structures, including toroids and rods. Here we report that solid supports treated with monovalent or multivalent cationic silanes, followed by removal of soluble molecules, can condense DNA. The mechanism of this surface-directed condensation depends on surface-mobile silanes, which are apparently recruited to the condensation site. The yield and species of DNA aggregates can be controlled by selecting the type of functional groups on surfaces, DNA and salt concentrations. For plasmid DNA, the toroidal form can represent >70% of adsorbed structures.

Adsorption↗